Publications
settings…
Direct Photolithographic Deposition of Color-Coded Anti-Counterfeit Patterns with Titania Encapsulated Upconverting Nanoparticles,
Zhang X, Ali RF, Boyer J-C, Branda NR and Gates BD,
Advanced Optical Materials
n/a
(n/a)
, 2000664
(2020),
|
| Abstract: Creating security labels as anti-counterfeit measures can require multi-step methods, clean room processing, and high-cost equipment. Some labels also have a limited applicability due to the ease of creating a counterfeit. Herein, a photochemical metal-organic deposition (PMOD) based approach that enables creation of high-resolution luminescent patterns that retain nanoparticles in transparent metal oxide films is reported. This low-cost, photoresist-free process creates high-resolution patterns of metal oxides without requiring processes such as etching or lift-off. Upconverting nanoparticles (UCNPs) with tunable red/green or blue emission are prepared by doping Yb3+/Er3+ and Yb3+/Tm3+ into ß-NaYF4 hosts, respectively. Luminescent inks are prepared by suspending UCNPs in solutions with titanium di-n-butoxide bis(2-ethylhexanoate). Customizable luminescent patterns are prepared by casting inks onto substrates, followed by exposure to ultraviolet light through photomasks. Photodecomposition of the titanium precursor yields amorphous oxide films encapsulating the UCNPs. Security labels are prepared by selectively patterning luminescent inks using PMOD. Distinct patterns of red-green-blue (RGB) luminescence are discernible only upon excitation with a near-infrared (NIR) laser. These customizable, anti-counterfeit labels exhibit the merits of low-cost, high-throughput, and simple manufacturing techniques. Yet, the versatility of customizing their emissive properties suggests a practical application as an anti-counterfeiting measure. |
BibTeX:
@article
{Zhang,
title = {Direct Photolithographic Deposition of Color-Coded Anti-Counterfeit Patterns with Titania Encapsulated Upconverting Nanoparticles}
,author = {Zhang, Xin and Ali, Rana Faryad and Boyer, John-Christopher and Branda, Neil R. and Gates, Byron D.}
,journal = {Advanced Optical Materials}
,year = {2020}
,volume = {n/a}
,number = {n/a}
,pages = {2000664}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adom.202000664}
,doi = {10.1002/adom.202000664}
}
|
Tunable Diffraction Gratings from Biosourced Lyotropic Liquid Crystals,
Cao Y, Wang P-X, D’Acierno F, Hamad WY, Michal CA and MacLachlan MJ,
Advanced Materials
32
(19)
, 1907376
(2020),
|
| Abstract: Diffraction gratings are important for modern optical components, such as optical multiplexers and signal processors. Although liquid crystal (LC) gratings based on thermotropic LCs have been extensively explored, they often require expensive molecules and complicated manufacturing processes. Lyotropic LCs, which can be broadly obtained from both synthetic and natural sources, have not yet been applied in optical gratings. Herein, a facile grating fabrication method using a biosourced lyotropic LC formed by cellulose nanocrystals (CNCs), a material extracted from plants, is reported. Hydrogel sheets with vertically aligned uniform periodic structures are obtained by fixing the highly oriented chiral nematic LC of CNCs in polymer networks under the cooperative effects of gravity on phase separation and a magnetic field on LC orientation. The hydrogel generates up to sixth-order diffraction spots and shows linear polarization selectivity, with tunable grating periodicity controlled through LC concentration regulation. This synthesis strategy can be broadly applied to various grating materials and opens up a new area of optical materials from lyotropic LCs. |
BibTeX:
@article
{Cao2020,
title = {Tunable Diffraction Gratings from Biosourced Lyotropic Liquid Crystals}
,author = {Cao, Yuanyuan and Wang, Pei-Xi and D'Acierno, Francesco and Hamad, Wadood Y. and Michal, Carl A. and MacLachlan, Mark J.}
,journal = {Advanced Materials}
,year = {2020}
,volume = {32}
,number = {19}
,pages = {1907376}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.201907376}
,doi = {10.1002/adma.201907376}
}
|
Investigation of the Energy Transfer Mechanism Between Semiconducting Polymer Dots and Organic Dyes,
Lix K, Krause KD, Kim H and Algar WR,
The Journal of Physical Chemistry C
124
(31)
, 17387-17400
(2020),
American Chemical Society.
|
| Abstract: Semiconducting polymer nanoparticles (Pdots) are a promising fluorescent probe for a wide variety of bioanalytical applications, including as donors in energy transfer (ET)-based sensing and photodynamic therapy. Although numerous Pdot-ET systems have been developed, detailed characterization of the ET mechanisms in these systems has been comparatively limited. Here, we studied the mechanism of ET between Pdot donors based on poly(9,9-dioctylfluorene-alt-benzothiadiazole) (F8BT) and a variety of cyanine and rhodamine dye acceptors using both steady-state and time-resolved spectroscopies. The dyes were either hydrophobic and nonspecifically associated with the Pdot core, or hydrophilic and specifically conjugated to the Pdot surface. Our data suggest that Förster resonance energy transfer (FRET) was the most probable and dominant mechanism of ET. There were no clear indications of photoinduced electron transfer (PET) and no need to distinguish Dexter ET from FRET, but there was an apparent decrease in the quantum yield of the acceptor dyes upon association with the Pdots. We also address how the physical characteristics of the Pdot system complicated and limited detailed photophysical study and models, and, in general, render simple FRET models both quantitatively and qualitatively inadequate. The results of our study contribute to a more complete understanding of the ET processes occurring in Pdot-acceptor systems, support the development of both new and improved applications based on Pdots and ET, and inform directions for further fundamental study. |
BibTeX:
@article
{Lix2020a,
title = {Investigation of the Energy Transfer Mechanism Between Semiconducting Polymer Dots and Organic Dyes}
,author = {Lix, Kelsi and Krause, Katherine D. and Kim, Hyungki and Algar, W. Russ}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2020}
,volume = {124}
,number = {31}
,pages = {17387--17400}
,url = {https://doi.org/10.1021/acs.jpcc.0c04983}
,doi = {10.1021/acs.jpcc.0c04983}
}
|
Controlling photocatalytic reduction of CO2 in Ru(II)/Re(I) dyads via linker oxidation state,
Brown CM, Auvray T, DeLuca EE, Ezhova MB, Hanan GS and Wolf MO,
Chemical Communications
(2020),
The Royal Society of Chemistry.
|
| Abstract: Electronic communication between the linked metal centers in Ru(II)–Re(I) dyads is tuned using the oxidation state (S and SO2) of sulfur-bridged ligands. Higher catalytic activity is seen for the SO2-bridged dyad in the photocatalytic reduction of CO2. |
BibTeX:
@article
{Brown2020,
title = {Controlling photocatalytic reduction of CO2 in Ru(II)/Re(I) dyads via linker oxidation state}
,author = {Brown, Christopher M. and Auvray, Thomas and DeLuca, Emile E. and Ezhova, Maria B. and Hanan, Garry S. and Wolf, Michael O.}
,journal = {Chemical Communications}
,publisher = {The Royal Society of Chemistry}
,year = {2020}
,url = {https://pubs.rsc.org/en/content/articlelanding/2020/cc/d0cc04597g}
,doi = {10.1039/D0CC04597G}
}
|
Fully Self-Assembled Silica Nanoparticle–Semiconductor Quantum Dot Supra-Nanoparticles and Immunoconjugates for Enhanced Cellular Imaging by Microscopy and Smartphone Camera,
Darwish GH, Asselin J, Tran MV, Gupta R, Kim H, Boudreau D and Algar WR,
ACS Applied Materials & Interfaces
12
(30)
, 33530-33540
(2020),
American Chemical Society.
|
| Abstract: There is a growing need for brighter luminescent materials to improve the detection and imaging of biomarkers. Relevant contexts include low-abundance biomarkers and technology-limited applications, where an example of the latter is the emerging use of smartphones and other nonoptimal but low-cost and portable devices for point-of-care diagnostics. One approach to achieving brighter luminescent materials is incorporating multiple copies of a luminescent material into a larger supra-nanoparticle (supra-NP) assembly. Here, we present a facile method for the preparation and immunoconjugation of supra-NP assemblies (SiO2@QDs) that comprised many quantum dots (QDs) around a central silica nanoparticle (SiO2 NP). The assembly was entirely driven by spontaneous affinity interactions between the constituent materials, which included imidazoline-functionalized silica nanoparticles, ligand-coated QDs, imidazole-functionalized dextran, and tetrameric antibody complexes (TACs). The physical and optical properties of the SiO2@QDs were characterized at both the ensemble and single-particle levels. Notably, the optical properties of the QDs were preserved upon assembly into supra-NPs, and single SiO2@QDs were approximately an order of magnitude brighter than single QDs and nonblinking. In proof-of-concept applications, including selective immunolabeling of breast cancer cells, the SiO2@QDs provided higher sensitivity and superior signal-to-background ratios whether using research-grade fluorescence microscopy or smartphone-based imaging. Overall, the SiO2@QDs are promising materials for enhanced bioanalysis and imaging. |
BibTeX:
@article
{Darwish2020,
title = {Fully Self-Assembled Silica Nanoparticle–Semiconductor Quantum Dot Supra-Nanoparticles and Immunoconjugates for Enhanced Cellular Imaging by Microscopy and Smartphone Camera}
,author = {Darwish, Ghinwa H. and Asselin, Jérémie and Tran, Michael V. and Gupta, Rupsa and Kim, Hyungki and Boudreau, Denis and Algar, W. Russ}
,journal = {ACS Applied Materials & Interfaces}
,publisher = {American Chemical Society}
,year = {2020}
,volume = {12}
,number = {30}
,pages = {33530--33540}
,url = {https://doi.org/10.1021/acsami.0c09553}
,doi = {10.1021/acsami.0c09553}
}
|
A Smart Phosphine–Diyne Polymer Displays “Turn-On” Emission with a High Selectivity for Gold(I/III) Ions,
Mackenzie HK, Rawe BW, Samedov K, Walsgrove HTG, Uva A, Han Z and Gates DP,
Journal of the American Chemical Society
142
(23)
, 10319-10324
(2020),
American Chemical Society.
|
| Abstract: A polymeric phosphine sensor is reported that exhibits bright blue fluorescence in the presence of gold(I/III) ions but is nonemissive with other metal ions. Specifically, solutions of a poly(p-arylenediethynylene phosphine) copolymer are 35 or 94 times more emissive when treated with solutions of (tht)AuCl or HAuCl4·3H2O, respectively. Model compound studies confirm phosphine coordination to metals, including gold(I/III) and rhodium(I), and the selective “turn-on” fluorescence was investigated using time-dependent density functional theory calculations. |
BibTeX:
@article
{Mackenzie2020,
title = {A Smart Phosphine–Diyne Polymer Displays “Turn-On” Emission with a High Selectivity for Gold(I/III) Ions}
,author = {Mackenzie, Harvey K. and Rawe, Benjamin W. and Samedov, Kerim and Walsgrove, Henry T. G. and Uva, Azalea and Han, Zeyu and Gates, Derek P.}
,journal = {Journal of the American Chemical Society}
,publisher = {American Chemical Society}
,year = {2020}
,volume = {142}
,number = {23}
,pages = {10319--10324}
,url = {https://doi.org/10.1021/jacs.0c04330}
,doi = {10.1021/jacs.0c04330}
}
|
Study of muonium emission from laser-ablated silica aerogel,
Beare J, Beer G, Brewer JH, Iijima T, Ishida K, Iwasaki M, Kamal S, Kanamori K, Kawamura N, Kitamura R, Li S, Luke GM, Marshall GM, Mibe T, Miyake Y, Oishi Y, Olchanski K, Olin A, Otani M, Rehman A, Saito N, Sato Y, Shimomura K, Suzuki K, Tabata M and Yasuda H,
arXiv:2006.01947 [hep-ex, physics:physics]
(2020),
|
| Abstract: The emission of muonium ($\mutextasciicircum+etextasciicircum-$) atoms into vacuum from silica aerogel with laser ablation on its surface was studied with various ablation structures at room temperature using the surface muon beams at TRIUMF and Japan Proton Accelerator Research Complex (J-PARC). Laser ablation was applied to produce holes or grooves with typical dimensions of a few hundred $\mu$m to a few mm, except for some extreme conditions. The measured emission rate tends to be higher for larger fractions of ablation opening and for shallower depths. More than a few ablation structures reach the emission rates similar to the highest achieved in the past measurements. The emission rate is found to be stable at least for a couple of days. Measurements of spin precession amplitudes for the produced muonium atoms and remaining muons in a magnetic field determine a muonium formation fraction of $(65.5 \pm 1.8)$% and indicate that the polarization of muonium atoms is preserved in vacuum. A projection of the emission rates measured at TRIUMF to the corresponding rates at J-PARC is demonstrated taking the different beam condition into account. The projected rates agree with the ones measured at J-PARC within the uncertainty of about $\pm$14%. |
BibTeX:
@article
{Beare2020,
title = {Study of muonium emission from laser-ablated silica aerogel}
,author = {Beare, J. and Beer, G. and Brewer, J. H. and Iijima, T. and Ishida, K. and Iwasaki, M. and Kamal, S. and Kanamori, K. and Kawamura, N. and Kitamura, R. and Li, S. and Luke, G. M. and Marshall, G. M. and Mibe, T. and Miyake, Y. and Oishi, Y. and Olchanski, K. and Olin, A. and Otani, M. and Rehman, A. and Saito, N. and Sato, Y. and Shimomura, K. and Suzuki, K. and Tabata, M. and Yasuda, H.}
,journal = {arXiv:2006.01947 [hep-ex, physics:physics]}
,year = {2020}
,note = {arXiv: 2006.01947}
,url = {http://arxiv.org/abs/2006.01947}
}
|
Stimuli-responsive flexible Lewis pair-modified nanoparticles for fluorescence imaging,
Arsenault NE, Downey KT and Wolf MO,
Chemical Communications
56
(44)
, 5981-5984
(2020),
The Royal Society of Chemistry.
|
| Abstract: A stimuli-responsive fluorophore, encompassing a Lewis acid–base pair, binds to primary amines on mesoporous silica nanoparticles, which may serve as environment-sensitive drug carriers. The fluorophore switches conformation, exhibiting different emission color and lifetimes, allowing for the detection of the water content of the nanoparticles’ surroundings through fluorescence spectroscopy and microscopy. |
BibTeX:
@article
{Arsenault2020,
title = {Stimuli-responsive flexible Lewis pair-modified nanoparticles for fluorescence imaging}
,author = {Arsenault, Nicole E. and Downey, Kathleen T. and Wolf, Michael O.}
,journal = {Chemical Communications}
,publisher = {The Royal Society of Chemistry}
,year = {2020}
,volume = {56}
,number = {44}
,pages = {5981--5984}
,url = {https://pubs.rsc.org/en/content/articlelanding/2020/cc/d0cc01203c}
,doi = {10.1039/D0CC01203C}
}
|
Scalable, Green Fabrication of Single-Crystal Noble Metal Films and Nanostructures for Low-Loss Nanotechnology Applications,
V. Grayli S, Zhang X, MacNab FC, Kamal S, Star D and Leach GW,
ACS Nano
(2020),
American Chemical Society.
|
| Abstract: The confinement of spatially extended electromagnetic waves to nanometer-scale metal structures can be harnessed for application in information processing, energy harvesting, sensing, and catalysis. Metal nanostructures enable negative refractive index, subwavelength resolution imaging, and patterning through engineered metamaterials and promise technologies that will operate in the quantum plasmonics regime. However, the controlled fabrication of high-definition single-crystal subwavelength metal nanostructures has remained a significant hurdle due to the tendency for polycrystalline metal growth using conventional physical vapor deposition methods and the challenges associated with placing solution-grown nanocrystals in desired orientations and locations on a surface to manufacture functional devices. Here, we introduce a scalable and green wet chemical approach to monocrystalline noble metal thin films and nanostructures. The method enables the fabrication of ultrasmooth, epitaxial, single-crystal films of controllable thickness that are ideal for the subtractive manufacture of nanostructures through ion beam milling and additive crystalline nanostructure via lithographic patterning for large-area, single-crystal metasurfaces and high aspect ratio nanowires. Our single-crystal nanostructures demonstrate improved feature quality, pattern transfer yield, reduced optical and resistive losses, and tailored local fields to yield greater optical response and improved stability compared to those of polycrystalline structures—supporting greater local field enhancements and enabling practical advances at the nanoscale. |
BibTeX:
@article
{V.Grayli2020,
title = {Scalable, Green Fabrication of Single-Crystal Noble Metal Films and Nanostructures for Low-Loss Nanotechnology Applications}
,author = {V. Grayli, Sasan and Zhang, Xin and MacNab, Finlay C. and Kamal, Saeid and Star, Dmitry and Leach, Gary W.}
,journal = {ACS Nano}
,publisher = {American Chemical Society}
,year = {2020}
,url = {https://doi.org/10.1021/acsnano.0c03466}
,doi = {10.1021/acsnano.0c03466}
}
|
Quinoline-containing diarylethenes: bridging between turn-on fluorescence, RGB switching and room temperature phosphorescence,
Xu Z, Liu QT, Wang X, Liu Q, Hean D, Chou KC and Wolf MO,
Chemical Science
11
(10)
, 2729-2734
(2020),
The Royal Society of Chemistry.
|
| Abstract: Simple structural modifications using oxidation and methylation of a quinoline-containing diarylethene result in dramatic variation of photophysical properties. Turn-on fluorescence, room temperature phosphorescence (RTP) and red-green-blue (RGB) switching were achieved in three different related compounds. Photoswitchable diarylethenes (DAEs) that exhibit turn-on fluorescence are in high demand for super-resolution microscopy, and the development of purely organic phosphorescent materials in the amorphous state is attractive but challenging. The findings reported here provide a novel toolkit for designing turn-on fluorescence DAEs for super-resolution microscopy and extending the scope of amorphous RTP materials. More importantly, we bridge between these two fundamentally significant photochemical and photophysical phenomena, and reveal structure–property relationships between DAE photochromism and RTP. |
BibTeX:
@article
{Xu2020,
title = {Quinoline-containing diarylethenes: bridging between turn-on fluorescence, RGB switching and room temperature phosphorescence}
,author = {Xu, Zhen and Liu, Qian T. and Wang, Xiaozhu and Liu, Qian and Hean, Duane and Chou, Keng C. and Wolf, Michael O.}
,journal = {Chemical Science}
,publisher = {The Royal Society of Chemistry}
,year = {2020}
,volume = {11}
,number = {10}
,pages = {2729--2734}
,url = {https://pubs.rsc.org/en/content/articlelanding/2020/sc/c9sc05697a}
,doi = {10.1039/C9SC05697A}
}
|
Unified Description of Diffusion Coefficients from Small to Large Molecules in Organic–Water Mixtures,
Evoy E, Kamal S, Patey GN, Martin ST and Bertram AK,
The Journal of Physical Chemistry A
124
(11)
, 2301-2308
(2020),
American Chemical Society.
|
| Abstract: Diffusion coefficients in mixtures of organic molecules and water are needed for many applications, ranging from the environmental modeling of pollutant transport, air quality, and climate, to improving the stability of foods, biomolecules, and pharmaceutical agents for longer use and storage. The Stokes–Einstein relation has been successful for predicting diffusion coefficients of large molecules in organic–water mixtures from viscosity, yet it routinely underpredicts, by orders of magnitude, the diffusion coefficients of small molecules in organic–water mixtures. Herein, a unified description of diffusion coefficients of large and small molecules in organic–water mixtures, based on the fractional Stokes–Einstein relation, is presented. A fractional Stokes–Einstein relation is able to describe 98% of the observed diffusion coefficients from small to large molecules, roughly within the uncertainties of the measurements. The data set used in the analysis includes a wide range of radii of diffusing molecules, viscosities, and intermolecular interactions. As a case study, we show that the degradation of polycyclic aromatic hydrocarbons (PAHs) by O3 within organic–water particles in the planetary boundary layer is relatively short (?1 day) when the viscosity of the particle is ?102 Pa s. We also show that the degradation times predicted using the Stokes–Einstein relation and the fractional Stokes–Einstein relation can differ by up to a factor of 10 in this region of the atmosphere. |
BibTeX:
@article
{Evoy2020,
title = {Unified Description of Diffusion Coefficients from Small to Large Molecules in Organic–Water Mixtures}
,author = {Evoy, Erin and Kamal, Saeid and Patey, Grenfell N. and Martin, Scot T. and Bertram, Allan K.}
,journal = {The Journal of Physical Chemistry A}
,publisher = {American Chemical Society}
,year = {2020}
,volume = {124}
,number = {11}
,pages = {2301--2308}
,url = {https://doi.org/10.1021/acs.jpca.9b11271}
,doi = {10.1021/acs.jpca.9b11271}
}
|
Color-Tunable Thermally Activated Delayed Fluorescence in Oxadiazole-Based Acrylic Copolymers: Photophysical Properties and Applications in Ratiometric Oxygen Sensing,
Tonge CM, Paisley NR, Polgar AM, Lix K, Algar WR and Hudson ZM,
ACS Applied Materials & Interfaces
12
(5)
, 6525-6535
(2020),
American Chemical Society.
|
| Abstract: Polymer-based emitters are a promising route to the production of low-cost, scalable solution-processable luminescent materials. Here we describe a series of acrylic oxadiazole-based donor–acceptor monomers with tunable emission from blue to orange, with quantum yields as high as 96%. By introducing structural constraints that limit donor–acceptor orbital overlap, thermally activated delayed fluorescence (TADF) was observed in these materials. Polymerization by Cu(0) reversible deactivation radical polymerization (RDRP) gave high-molecular-weight copolymers (Mn textgreater 20 kDa) with dispersities ranging from 1.10 to 1.45, using a room-temperature procedure with Cu wire as a catalyst. One of these materials, which had phenothiazine as donor moiety, exhibited conformationally dependent dual emission, giving a mixture of prompt fluorescence and delayed fluorescence peaks, whose relative ratios varied based on the amount of O2 present during measurement. We demonstrate that this material can combine prompt and delayed fluorescence to act as a single-component, all-organic, ratiometric oxygen sensor without external calibrant. Application to ratiometric oxygen sensing is demonstrated both using a polymer thin film and via incorporation of this material into water-soluble polymer dots (Pdots), with a ratiometric response to O2 throughout the range of partial pressures relevant to biological environments. |
BibTeX:
@article
{Tonge2020,
title = {Color-Tunable Thermally Activated Delayed Fluorescence in Oxadiazole-Based Acrylic Copolymers: Photophysical Properties and Applications in Ratiometric Oxygen Sensing}
,author = {Tonge, Christopher M. and Paisley, Nathan R. and Polgar, Alexander M. and Lix, Kelsi and Algar, W. Russ and Hudson, Zachary M.}
,journal = {ACS Applied Materials & Interfaces}
,publisher = {American Chemical Society}
,year = {2020}
,volume = {12}
,number = {5}
,pages = {6525--6535}
,url = {https://doi.org/10.1021/acsami.9b22464}
,doi = {10.1021/acsami.9b22464}
}
|
Dextran Functionalization of Semiconducting Polymer Dots and Conjugation with Tetrameric Antibody Complexes for Bioanalysis and Imaging,
Lix K, Tran MV, Massey M, Rees K, Sauvé ER, Hudson ZM and Algar WR,
ACS Applied Bio Materials
3
(1)
, 432-440
(2020),
American Chemical Society.
|
| Abstract: Brightly fluorescent semiconducting polymer dots (Pdots) are emerging as very useful probes for bioanalysis and imaging. Unfortunately, Pdot materials often suffer from limitations such as poor colloidal and physical stability, nonspecific adsorption, and relatively few reported surface chemistries and bioconjugate chemistries. To help address these limitations, we have developed dextran-functionalized Pdots (Dex-Pdots). This functionalization improves particle stability over a range of pH and at high ionic strength, hinders surface-induced unfolding, and enables the preparation of immunoconjugates via tetrameric antibody complexes (TAC). The utility of TAC-conjugated Dex-Pdots is demonstrated through a proof-of-concept fluorescence-linked immunosorbent assay (FLISA) for human erythropoietin (EPO), and through immunolabeling of human epidermal growth factor receptor 2 (HER2)-positive SK-BR3 breast cancer cells. The conjugates exhibited less nonspecific binding and greater specific binding than Pdots without dextran functionalization. Overall, dextran functionalization is a highly promising surface chemistry for biological applications of Pdots. |
BibTeX:
@article
{Lix2020,
title = {Dextran Functionalization of Semiconducting Polymer Dots and Conjugation with Tetrameric Antibody Complexes for Bioanalysis and Imaging}
,author = {Lix, Kelsi and Tran, Michael V. and Massey, Melissa and Rees, Kelly and Sauvé, Ethan R. and Hudson, Zachary M. and Algar, W. Russ}
,journal = {ACS Applied Bio Materials}
,publisher = {American Chemical Society}
,year = {2020}
,volume = {3}
,number = {1}
,pages = {432--440}
,url = {https://doi.org/10.1021/acsabm.9b00899}
,doi = {10.1021/acsabm.9b00899}
}
|
Cucurbituril-mediated quantum dot aggregates formed by aqueous self-assembly for sensing applications,
J. Peveler W, Jia H, Jeen T, Rees K, J. Macdonald T, Xia Z, Katherine Chio W-I, Moorthy S, P. Parkin I, J. Carmalt C, Algar WR and Lee T-C,
Chemical Communications
55
(38)
, 5495-5498
(2019),
Royal Society of Chemistry.
|
BibTeX:
@article
{J. Peveler2019,
title = {Cucurbituril-mediated quantum dot aggregates formed by aqueous self-assembly for sensing applications}
,author = {J. Peveler, William and Jia, Hui and Jeen, Tiffany and Rees, Kelly and J. Macdonald, Thomas and Xia, Zhicheng and Katherine Chio, Weng-I. and Moorthy, Suresh and P. Parkin, Ivan and J. Carmalt, Claire and Algar, W. Russ and Lee, Tung-Chun}
,journal = {Chemical Communications}
,publisher = {Royal Society of Chemistry}
,year = {2019}
,volume = {55}
,number = {38}
,pages = {5495--5498}
,url = {https://pubs.rsc.org/en/content/articlelanding/2019/cc/c9cc00410f}
,doi = {10.1039/C9CC00410F}
}
|
Many-body recombination in photoexcited insulating cuprates,
Sahota DG, Liang R, Dion M, Fournier P, Dabkowska HA, Luke GM and Dodge JS,
Physical Review Research
1
(3)
, 033214
(2019),
American Physical Society.
|
| Abstract: We study the pump-probe response of three insulating cuprates and develop a model for its recombination kinetics. The dependence on time, fluence, and both pump and probe photon energies implies many-body recombination on femtosecond timescales, characterized by anomalously large trapping and Auger coefficients. The fluence dependence follows a universal form that includes a characteristic volume scale, which we associate with the holon-doublon excitation efficiency. This volume varies strongly with pump photon energy and peaks at nearly twice the charge-transfer energy, suggesting that the variation is caused by carrier multiplication through impact ionization. |
BibTeX:
@article
{Sahota2019,
title = {Many-body recombination in photoexcited insulating cuprates}
,author = {Sahota, Derek G. and Liang, Ruixing and Dion, M. and Fournier, Patrick and Dabkowska, Hanna A. and Luke, Graeme M. and Dodge, J. Steven}
,journal = {Physical Review Research}
,publisher = {American Physical Society}
,year = {2019}
,volume = {1}
,number = {3}
,pages = {033214}
,url = {https://link.aps.org/doi/10.1103/PhysRevResearch.1.033214}
,doi = {10.1103/PhysRevResearch.1.033214}
}
|
Dopant-free molecular hole transport material that mediates a 20% power conversion efficiency in a perovskite solar cell,
Cao Y, Li Y, Morrissey T, Lam B, Patrick BO, Dvorak DJ, Xia Z, Kelly TL and Berlinguette CP,
Energy & Environmental Science
12
(12)
, 3502-3507
(2019),
The Royal Society of Chemistry.
|
| Abstract: Organic molecular hole-transport materials (HTMs) are appealing for the scalable manufacture of perovskite solar cells (PSCs) because they are easier to reproducibly prepare in high purity than polymeric and inorganic HTMs. There is also a need to construct PSCs without dopants and additives to avoid formidable engineering and stability issues. We report here a power conversion efficiency (PCE) of 20.6% with a molecular HTM in an inverted (p–i–n) PSC without any dopants or interlayers. This new benchmark was made possible by the discovery that, upon annealing, a spiro-based dopant-free HTM (denoted DFH) containing redox-active triphenyl amine (TPA) units undergoes preferential molecular organization normal to the substrate. This structural order, governed by the strong intermolecular interactions of the DFH dioxane groups, affords high intrinsic hole mobility (1 × 10-3 cm2 V-1 s-1). Annealing films of DFH also enables the growth of large perovskite grains (up to 2 µm) that minimize charge recombination in the PSC. DFH can also be isolated at a fraction of the cost of any other organic HTM. |
BibTeX:
@article
{Cao2019,
title = {Dopant-free molecular hole transport material that mediates a 20% power conversion efficiency in a perovskite solar cell}
,author = {Cao, Yang and Li, Yunlong and Morrissey, Thomas and Lam, Brian and Patrick, Brian O. and Dvorak, David J. and Xia, Zhicheng and Kelly, Timothy L. and Berlinguette, Curtis P.}
,journal = {Energy & Environmental Science}
,publisher = {The Royal Society of Chemistry}
,year = {2019}
,volume = {12}
,number = {12}
,pages = {3502--3507}
,url = {https://pubs.rsc.org/en/content/articlelanding/2019/ee/c9ee02983d}
,doi = {10.1039/C9EE02983D}
}
|
Green solvent assisted synthesis of cesium bismuth halide perovskite nanocrystals and the influences of slow and fast anion exchange rates,
Ali RF, Andreu I and Gates BD,
Nanoscale Advances
1
(11)
, 4442-4449
(2019),
RSC.
|
| Abstract: Replacing lead in halide perovskites to address the concerns of their toxicity and stability has driven a recent surge in research toward alternative lead-free perovskite materials. Lead-free all inorganic cesium bismuth halide (Cs3Bi2X9) perovskite nanocrystals have attracted attention in recent years due to the air-stability and non-toxic nature of bismuth. Herein, we demonstrate a facile sonication-assisted approach for the preparation of all-inorganic cesium bismuth iodide (Cs3Bi2I9) perovskite nanocrystals (NCs) using propylene carbonate as a green, alternative solvent. The photoluminescence (PL) spectra of the Cs3Bi2X9 NCs have a peak emission that can be tuned from 410 to 550 nm by controlling the composition of the NCs through an anion exchange reaction using tetraalkylammonium halides as a source of halide ions. The rate of this anion exchange reaction is demonstrated to have a significant influence on the dimensions of the NCs obtained from the parent Cs3Bi2I9 NCs. The PL emission of these nanocrystals is predominately due to exciton recombination processes. The NCs also exhibit air-stability for at least 150 days. |
BibTeX:
@article
{Ali2019a,
title = {Green solvent assisted synthesis of cesium bismuth halide perovskite nanocrystals and the influences of slow and fast anion exchange rates}
,author = {Ali, Rana Faryad and Andreu, Irene and Gates, Byron D.}
,journal = {Nanoscale Advances}
,publisher = {RSC}
,year = {2019}
,volume = {1}
,number = {11}
,pages = {4442--4449}
,url = {https://pubs.rsc.org/en/content/articlelanding/2019/na/c9na00586b}
,doi = {10.1039/C9NA00586B}
}
|
Diffusion of Organic Molecules as a Function of Temperature in a Sucrose Matrix (a Proxy for Secondary Organic Aerosol),
Kiland KJ, Maclean AM, Kamal S and Bertram AK,
The Journal of Physical Chemistry Letters
10
(19)
, 5902-5908
(2019),
American Chemical Society.
|
| Abstract: Knowledge of diffusion coefficients as a function of temperature in secondary organic aerosol (SOA) or proxies of SOA is needed to predict atmospheric chemistry, climate, and air quality. We determined diffusion coefficients as a function of temperature of a fluorescent organic molecule in a sucrose matrix (a proxy for SOA). Diffusion coefficients were a strong function of temperature (e.g., at water activity = 0.43, diffusion coefficients decreased by a factor of 40 as the temperature decreased by 20 K). Interestingly, the apparent activation energy for diffusion of the fluorescent organic molecule was similar to the apparent activation for diffusion of water in the sucrose matrix. On the basis of these measurements, the mixing time of organic molecules by diffusion in some types of SOA particles will often be textgreater1 h in the free troposphere, if a sucrose matrix is an accurate proxy for these types of SOA. |
BibTeX:
@article
{Kiland2019,
title = {Diffusion of Organic Molecules as a Function of Temperature in a Sucrose Matrix (a Proxy for Secondary Organic Aerosol)}
,author = {Kiland, Kristian J. and Maclean, Adrian M. and Kamal, Saeid and Bertram, Allan K.}
,journal = {The Journal of Physical Chemistry Letters}
,publisher = {American Chemical Society}
,year = {2019}
,volume = {10}
,number = {19}
,pages = {5902--5908}
,url = {https://doi.org/10.1021/acs.jpclett.9b02182}
,doi = {10.1021/acs.jpclett.9b02182}
}
|
Predictions of diffusion rates of large organic molecules in secondary organic aerosols using the Stokes–Einstein and fractional Stokes–Einstein relations,
Evoy E, Maclean AM, Rovelli G, Li Y, Tsimpidi AP, Karydis VA, Kamal S, Lelieveld J, Shiraiwa M, Reid JP and Bertram AK,
Atmospheric Chemistry and Physics (Online)
19
(15)
(2019),
European Geosciences Union.
|
| Abstract: The U.S. Department of Energy’s Office of Scientific and Technical Information |
BibTeX:
@article
{Evoy2019,
title = {Predictions of diffusion rates of large organic molecules in secondary organic aerosols using the Stokes–Einstein and fractional Stokes–Einstein relations}
,author = {Evoy, Erin and Maclean, Adrian M. and Rovelli, Grazia and Li, Ying and Tsimpidi, Alexandra P. and Karydis, Vlassis A. and Kamal, Saeid and Lelieveld, Jos and Shiraiwa, Manabu and Reid, Jonathan P. and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics (Online)}
,publisher = {European Geosciences Union}
,year = {2019}
,volume = {19}
,number = {15}
,url = {https://www.osti.gov/pages/biblio/1581748}
,doi = {10.5194/acp-19-10073-2019}
}
|
Models for the bead mobility technique: A droplet-based viscometer,
Sellier M, Taylor J, Bertram AK and Mandin P,
Aerosol Science and Technology
53
(7)
, 749-759
(2019),
Taylor & Francis.
|
| Abstract: Better understanding the properties of organic aerosols (OA) is attracting increasing attention because of the important role they play in climate change. The viscosity of OA has been shown to range from liquid to solid/semi-solid across the range of atmospheric relative humidity. A method known as the “bead-mobility technique” has been developed to quantify the viscosity of an atmospheric particle over a range of atmospherically relevant humidities. The method is based on the assumption that the strength of the flow recirculation inside a droplet placed in a shear flow is related to the droplet viscosity. This article presents a simple analytical model which predicts the internal flow in the droplet and provides a correlation relating the strength of the flow in the droplet to its viscosity. The validity of this analytical model is assessed by comparing the analytical results with a corresponding two-phase flow simulation with a moving mesh which captures the motion of the interface. The ability of the analytical model to reproduce experimental data reported in the literature is also quantified. The reasonable agreement between the analytical model and the experimental data confirms that the droplet velocity provides a useful proxy to estimate the droplet viscosity for small liquid samples for which standard viscometry techniques do not apply.Copyright © 2019 American Association for Aerosol Research |
BibTeX:
@article
{Sellier2019,
title = {Models for the bead mobility technique: A droplet-based viscometer}
,author = {Sellier, M. and Taylor, J. and Bertram, Allan K. and Mandin, P.}
,journal = {Aerosol Science and Technology}
,publisher = {Taylor & Francis}
,year = {2019}
,volume = {53}
,number = {7}
,pages = {749--759}
,url = {https://doi.org/10.1080/02786826.2019.1599320}
,doi = {10.1080/02786826.2019.1599320}
}
|
Influence of Sulfur Oxidation State and Substituents on Sulfur-Bridged Luminescent Copper(I) Complexes Showing Thermally Activated Delayed Fluorescence,
Brown CM, Li C, Carta V, Li W, Xu Z, Stroppa PHF, Samuel IDW, Zysman-Colman E and Wolf MO,
Inorganic Chemistry
58
(11)
, 7156-7168
(2019),
American Chemical Society.
|
| Abstract: Copper(I) complexes are seen as more sustainable alternatives to those containing metal ions such as iridium and platinum for emitting devices. Copper(I) complexes have the ability to radiatively decay via a thermally activated delayed fluorescence (TADF) pathway, leading to higher photoluminescent quantum yields. In this work we discuss six new heteroleptic Cu(I) complexes of the diphosphine–diimine motif. The diphosphine ligands employed are (oxidi-2,1-phenylene)bis(diphenylphosphine) (DPEPhos), and the diimine fragments are sulfur-bridged dipyridyl ligands (DPS) which are functionalized at the 6,6′-positions of the pyridyl rings (R = H, Me, Ph) and have varying oxidation states at the bridging sulfur atom (S, SO2). The proton (Cu-DPS, Cu-DPSO2) and phenyl (Cu-Ph-DPS, Cu-Ph-DPSO2) substituted species are found to form monometallic complexes, while those with methyl substitution (Cu-Me-DPS, Cu-Me-DPSO2) are found to have a “Goldilocks” degree of steric bulk leading to bimetallic species. All six Cu(I) complexes show emission in the solid state, with the photophysical properties characterized by low temperature steady-state and time-resolved spectroscopies and variable temperature time-correlated single photon counting. Cu-DPS, Cu-DPSO2, Cu-Me-DPS, Cu-Me-DPSO2, and Cu-Ph-DPSO2 were shown to emit via a TADF mechanism, while Cu-Ph-DPS showed photoluminescence properties consistent with triplet ligand-centered (3LC) emission. |
BibTeX:
@article
{Brown2019,
title = {Influence of Sulfur Oxidation State and Substituents on Sulfur-Bridged Luminescent Copper(I) Complexes Showing Thermally Activated Delayed Fluorescence}
,author = {Brown, Christopher M. and Li, Chenfei and Carta, Veronica and Li, Wenbo and Xu, Zhen and Stroppa, Pedro Henrique Fazza and Samuel, Ifor D. W. and Zysman-Colman, Eli and Wolf, Michael O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2019}
,volume = {58}
,number = {11}
,pages = {7156--7168}
,url = {https://doi.org/10.1021/acs.inorgchem.8b03500}
,doi = {10.1021/acs.inorgchem.8b03500}
}
|
One-pot synthesis of sub-10 nm LiNbO3 nanocrystals exhibiting a tunable optical second harmonic response,
Ali RF, Bilton M and Gates BD,
Nanoscale Advances
1
(6)
, 2268-2275
(2019),
RSC.
|
| Abstract: Nanophotonics, dealing with the properties of light interacting with nanometer scale materials and structures, has emerged as a sought after platform for sensing and imaging applications, and is impacting fields that include advanced information technology, signal processing circuits, and cryptography. Lithium niobate (LiNbO3) is a unique photonic material, often referred to as the “silicon of photonics” due to its excellent optical properties. In this article, we introduce a solution-phase method to prepare single-crystalline LiNbO3 nanoparticles with average diameters of 7 nm. This one-pot approach forms well-dispersed LiNbO3 nanocrystals without additional organic additives (e.g., surfactants) to control growth and aggregation of the nanoparticles. Formation of these LiNbO3 nanocrystals proceeds through a non-aqueous sol–gel reaction, in which lithium hydroxide and niobium hydroxide species were generated in situ. The reaction proceeded through both a condensation and crystallization of these reactants to form the solid nanoparticles. These nanocrystals of LiNbO3 were active for optical second harmonic generation (SHG) with a tunable response from 400 to 500 nm. These nanoparticles could enable further development of non-linear optical techniques such as SHG microscopy for bioimaging, which requires the dimensions of nanoparticles to be well below 100 nm. |
BibTeX:
@article
{Ali2019,
title = {One-pot synthesis of sub-10 nm LiNbO3 nanocrystals exhibiting a tunable optical second harmonic response}
,author = {Ali, Rana Faryad and Bilton, Matthew and Gates, Byron D.}
,journal = {Nanoscale Advances}
,publisher = {RSC}
,year = {2019}
,volume = {1}
,number = {6}
,pages = {2268--2275}
,url = {https://pubs.rsc.org/en/content/articlelanding/2019/na/c8na00171e}
,doi = {10.1039/C8NA00171E}
}
|
A new approach for measuring the muon anomalous magnetic moment and electric dipole moment,
Abe M, Bae S, Beer G, Bunce G, Choi H, Choi S, Chung M, da Silva W, Eidelman S, Finger M, Fukao Y, Fukuyama T, Haciomeroglu S, Hasegawa K, Hayasaka K, Hayashizaki N, Hisamatsu H, Iijima T, Iinuma H, Ikeda H, Ikeno M, Inami K, Ishida K, Itahashi T, Iwasaki M, Iwashita Y, Iwata Y, Kadono R, Kamal S, Kamitani T, Kanda S, Kapusta F, Kawagoe K, Kawamura N, Kim B, Kim Y, Kishishita T, Kitamura R, Ko H, Kohriki T, Kondo Y, Kume T, Lee MJ, Lee S, Lee W, Marshall GM, Matsuda Y, Mibe T, Miyake Y, Murakami T, Nagamine K, Nakayama H, Nishimura S, Nomura D, Ogitsu T, Ohsawa S, Oide K, Oishi Y, Okada S, Olin A, Omarov Z, Otani M, Razuvaev G, Rehman A, Saito N, Saito NF, Sasaki K, Sasaki O, Sato N, Sato Y, Semertzidis YK, Sendai H, Shatunov Y, Shimomura K, Shoji M, Shwartz B, Strasser P, Sue Y, Suehara T, Sung C, Suzuki K, Takatomi T, Tanaka M, Tojo J, Tsutsumi Y, Uchida T, Ueno K, Wada S, Won E, Yamaguchi H, Yamanaka T, Yamamoto A, Yamazaki T, Yasuda H, Yoshida M and Yoshioka T,
Progress of Theoretical and Experimental Physics
2019
(5)
(2019),
Oxford Academic.
|
| Abstract: Abstract. This paper introduces a new approach to measure the muon magnetic moment anomaly $a{\textbackslash}mu\ = (g-2)/2$ and the muon electric dipole moment (EDM) $d\vphantom{\}\m |
BibTeX:
@article
{Abe2019,
title = {A new approach for measuring the muon anomalous magnetic moment and electric dipole moment}
,author = {Abe, M. and Bae, S. and Beer, G. and Bunce, G. and Choi, H. and Choi, S. and Chung, M. and da Silva, W. and Eidelman, S. and Finger, M. and Fukao, Y. and Fukuyama, T. and Haciomeroglu, S. and Hasegawa, K. and Hayasaka, K. and Hayashizaki, N. and Hisamatsu, H. and Iijima, T. and Iinuma, H. and Ikeda, H. and Ikeno, M. and Inami, K. and Ishida, K. and Itahashi, T. and Iwasaki, M. and Iwashita, Y. and Iwata, Y. and Kadono, R. and Kamal, S. and Kamitani, T. and Kanda, S. and Kapusta, F. and Kawagoe, K. and Kawamura, N. and Kim, B. and Kim, Y. and Kishishita, T. and Kitamura, R. and Ko, H. and Kohriki, T. and Kondo, Y. and Kume, T. and Lee, M. J. and Lee, S. and Lee, W. and Marshall, G. M. and Matsuda, Y. and Mibe, T. and Miyake, Y. and Murakami, T. and Nagamine, K. and Nakayama, H. and Nishimura, S. and Nomura, D. and Ogitsu, T. and Ohsawa, S. and Oide, K. and Oishi, Y. and Okada, S. and Olin, A. and Omarov, Z. and Otani, M. and Razuvaev, G. and Rehman, A. and Saito, N. and Saito, N. F. and Sasaki, K. and Sasaki, O. and Sato, N. and Sato, Y. and Semertzidis, Y. K. and Sendai, H. and Shatunov, Y. and Shimomura, K. and Shoji, M. and Shwartz, B. and Strasser, P. and Sue, Y. and Suehara, T. and Sung, C. and Suzuki, K. and Takatomi, T. and Tanaka, M. and Tojo, J. and Tsutsumi, Y. and Uchida, T. and Ueno, K. and Wada, S. and Won, E. and Yamaguchi, H. and Yamanaka, T. and Yamamoto, A. and Yamazaki, T. and Yasuda, H. and Yoshida, M. and Yoshioka, T.}
,journal = {Progress of Theoretical and Experimental Physics}
,publisher = {Oxford Academic}
,year = {2019}
,volume = {2019}
,number = {5}
,url = {https://academic.oup.com/ptep/article/2019/5/053C02/5506729}
,doi = {10.1093/ptep/ptz030}
}
|
Comparison of Approaches for Measuring and Predicting the Viscosity of Ternary Component Aerosol Particles,
Rovelli G, Song Y-C, Maclean AM, Topping DO, Bertram AK and Reid JP,
Analytical Chemistry
91
(8)
, 5074-5082
(2019),
American Chemical Society.
|
| Abstract: Measurements of the water activity-dependent viscosity of aerosol particles from two techniques are compared, specifically from the coalescence of two droplets in holographic optical tweezers (HOT) and poke-and-flow experiments on particles deposited onto a glass substrate. These new data are also compared with the fitting of dimer coagulation, isolation, and coalescence (DCIC) measurements. The aerosol system considered in this work are ternary mixtures of sucrose-citric acid-water and sucrose-NaNO3-water, at varying solute mass ratios. Results from HOT and poke-and-flow are in excellent agreement over their overlapping range of applicability ( 103–107 Pa s); fitted curves from DCIC data show variable agreement with the other two techniques because of the sensitivity of the applied modeling framework to the representation of water content in the particles. Further, two modeling approaches for the predictions of the water activity-dependent viscosity of these ternary systems are evaluated. We show that it is possible to represent their viscosity with relatively simple mixing rules applied to the subcooled viscosity values of each component or to the viscosity of the corresponding binary mixtures. |
BibTeX:
@article
{Rovelli2019,
title = {Comparison of Approaches for Measuring and Predicting the Viscosity of Ternary Component Aerosol Particles}
,author = {Rovelli, Grazia and Song, Young-Chul and Maclean, Adrian M. and Topping, David O. and Bertram, Allan K. and Reid, Jonathan P.}
,journal = {Analytical Chemistry}
,publisher = {American Chemical Society}
,year = {2019}
,volume = {91}
,number = {8}
,pages = {5074--5082}
,url = {https://doi.org/10.1021/acs.analchem.8b05353}
,doi = {10.1021/acs.analchem.8b05353}
}
|
Viscosities, diffusion coefficients, and mixing times of intrinsic fluorescent organic molecules in brown limonene secondary organic aerosol and tests of the Stokes–Einstein equation,
Ullmann DA, Hinks ML, Maclean AM, Butenhoff CL, Grayson JW, Barsanti K, Jimenez JL, Nizkorodov SA, Kamal S and Bertram AK,
Atmospheric Chemistry and Physics
19
(3)
, 1491-1503
(2019),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater Viscosities and diffusion rates of organics within secondary organic aerosol (SOA) remain uncertain. Using the bead-mobility technique, we measured viscosities as a function of water activity (textlessspan class=inline-formulatextgreatera_wtextless/spantextgreater) of SOA generated by the ozonolysis of limonene followed by browning by exposure to textlessspan class=inline-formulatextgreaterNH_3textless/spantextgreater (referred to as brown limonene SOA or brown LSOA). These measurements together with viscosity measurements reported in the literature show that the viscosity of brown LSOA increases by 3–5 orders of magnitude as the textlessspan class=inline-formulatextgreatera_wtextless/spantextgreater decreases from 0.9 to approximately 0.05. In addition, we measured diffusion coefficients of intrinsic fluorescent organic molecules within brown LSOA matrices using rectangular area fluorescence recovery after photobleaching. Based on the diffusion measurements, as the textlessspan class=inline-formulatextgreatera_wtextless/spantextgreater decreases from 0.9 to 0.33, the average diffusion coefficient of the intrinsic fluorescent organic molecules decreases from textlessspan class=inline-formulatextgreatertextlessmath xmlns=http://www.w3.org/1998/Math/MathML id=M5 display=inline overflow=scroll dspmath=mathmltextgreatertextlessmrowtextgreatertextlessmn mathvariant=normaltextgreater5.5textless/mntextgreatertextlessmotextgreater×textless/motextgreatertextlessmsuptextgreatertextlessmn mathvariant=normaltextgreater10textless/mntextgreatertextlessmrowtextgreatertextlessmotextgreater-textless/motextgreatertextlessmn mathvariant=normaltextgreater9textless/mntextgreatertextless/mrowtextgreatertextless/msuptextgreatertextless/mrowtextgreatertextless/mathtextgreatertextlessspantextgreatertextlesssvg:svg xmlns:svg=http://www.w3.org/2000/svg width=51pt height=14pt class=svg-formula dspmath=mathimg md5hash=6c4c63375ff885c7d6d1a8e725667a4ctextgreatertextlesssvg:image xmlns:xlink=http://www.w3.org/1999/xlink xlink:href=acp-19-1491-2019-ie00001.svg width=51pt height=14pt src=acp-19-1491-2019-ie00001.png/textgreatertextless/svg:svgtextgreatertextless/spantextgreatertextless/spantextgreater to textlessspan class=inline-formulatextgreatertextlessmath xmlns=http://www.w3.org/1998/Math/MathML id=M6 display=inline overflow=scroll dspmath=mathmltextgreatertextlessmrowtextgreatertextlessmn mathvariant=normaltextgreater7.1textless/mntextgreatertextlessmotextgreater×textless/motextgreatertextlessmsuptextgreatertextlessmn mathvariant=normaltextgreater10textless/mntextgreatertextlessmrowtextgreatertextlessmotextgreater-textless/motextgreatertextlessmn mathvariant=normaltextgreater13textless/mntextgreatertextless/mrowtextgreatertextless/msuptextgreatertextless/mrowtextgreatertextless/mathtextgreatertextlessspantextgreatertextlesssvg:svg xmlns:svg=http://www.w3.org/2000/svg width=55pt height=14pt class=svg-formula dspmath=mathimg md5hash=01f92ec1f17e6e4f6cd525b9f501bfa9textgreatertextlesssvg:image xmlns:xlink=http://www.w3.org/1999/xlink xlink:href=acp-19-1491-2019-ie00002.svg width=55pt height=14pt src=acp-19-1491-2019-ie00002.png/textgreatertextless/svg:svgtextgreatertextless/spantextgreatertextless/spantextgreater cmtextlessspan class=inline-formulatextgreater^2textless/spantextgreater stextlessspan class=inline-formulatextgreater^-1textless/spantextgreater and the mixing times of intrinsic fluorescent organic molecules within 200 nm brown LSOA particles increases from 0.002 to 14 s. These results suggest that the mixing times of large organics in the brown LSOA studied here are short (textlessspan class=inline-formulatextgreater<1textless/spantextgreater h) for textlessspan class=inline-formulatextgreatera_wtextless/spantextgreater and temperatures often found in the planetary boundary layer (PBL). Since the diffusion coefficients and mixing times reported here correspond to SOA generated using a high mass loading (textlessspan class=inline-formulatextgreater 1000textless/spantextgreater textlessspan class=inline-formulatextgreaterµtextless/spantextgreaterg mtextlessspan class=inline-formulatextgreater^-3textless/spantextgreater), biogenic SOA particles found in the atmosphere with mass loadings textlessspan class=inline-formulatextgreater=10textless/spantextgreater textlessspan class=inline-formulatextgreaterµtextless/spantextgreaterg mtextlessspan class=inline-formulatextgreater^-3textless/spantextgreater are likely to have higher viscosities and longer mixing times (possibly 3 orders of magnitude longer). These new measurements of viscosity and diffusion were used to test the accuracy of the Stokes–Einstein relation for predicting diffusion rates of organics within brown LSOA matrices. The results show that the Stokes–Einstein equation gives accurate predictions of diffusion coefficients of large organics within brown LSOA matrices when the viscosity of the matrix is as high as textlessspan class=inline-formulatextgreater10^2textless/spantextgreater to textlessspan class=inline-formulatextgreater10^4textless/spantextgreater Pa s. These results have important implications for predicting diffusion and mixing within SOA particles in the atmosphere.textless/ptextgreater |
BibTeX:
@article
{Ullmann2019,
title = {Viscosities, diffusion coefficients, and mixing times of intrinsic fluorescent organic molecules in brown limonene secondary organic aerosol and tests of the Stokes–Einstein equation}
,author = {Ullmann, Dagny A. and Hinks, Mallory L. and Maclean, Adrian M. and Butenhoff, Christopher L. and Grayson, James W. and Barsanti, Kelley and Jimenez, Jose L. and Nizkorodov, Sergey A. and Kamal, Saeid and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2019}
,volume = {19}
,number = {3}
,pages = {1491--1503}
,url = {https://acp.copernicus.org/articles/19/1491/2019/}
,doi = {10.5194/acp-19-1491-2019}
}
|
Fluorescent Heterotelechelic Single-Chain Polymer Nanoparticles: Synthesis, Spectroscopy, and Cellular Imaging,
Bajj DNF, Tran MV, Tsai H-Y, Kim H, Paisley NR, Algar WR and Hudson ZM,
ACS Applied Nano Materials
2
(2)
, 898-909
(2019),
American Chemical Society.
|
| Abstract: The folding and collapse of individual polymer chains into single-chain polymer nanoparticles (SCPNs) is a versatile and emerging platform for biological applications such as diagnostics, imaging, and therapy, where components for two or more of these functions can be combined onto a single polymer carrier. Here, we prepare heterotelechelic polymers with three sets of separately addressable chemical handles at their a-terminus and ?-terminus, and along their backbone. As a model system, the a- and ?-termini are conjugated with a targeting ligand (folic acid or biotin) and therapeutic drug cargo (camptothecin), respectively, and the backbone is grafted with pendant fluorescent dye molecules, poly(ethylene glycol) oligomers, and benzene-1,3,5-tricarboxamide. These polymers fold in water to give fluorescent SCPNs, which are characterized with respect to their physical and photophysical properties. The latter reveals a relationship between polymer folding, quantum yield, and resistance to photobleaching. The SCPNs are then shown to be useful for immunolabeling of SK-BR-3 breast cancer cells and exhibit little or no acute cytotoxicity. This work demonstrates that SCPNs can be used as a viable platform for bioconjugation and cell labeling, helps establish a set of design criteria for optimizing future biological applications, and opens the door to the development of SCPNs for a broader range of theranostic applications. |
BibTeX:
@article
{Bajj2019,
title = {Fluorescent Heterotelechelic Single-Chain Polymer Nanoparticles: Synthesis, Spectroscopy, and Cellular Imaging}
,author = {Bajj, Daniel N. F. and Tran, Michael V. and Tsai, Hsin-Yun and Kim, Hyungki and Paisley, Nathan R. and Algar, W. Russ and Hudson, Zachary M.}
,journal = {ACS Applied Nano Materials}
,publisher = {American Chemical Society}
,year = {2019}
,volume = {2}
,number = {2}
,pages = {898--909}
,url = {https://doi.org/10.1021/acsanm.8b02149}
,doi = {10.1021/acsanm.8b02149}
}
|
Template assisted preparation of high surface area macroporous supports with uniform and tunable nanocrystal loadings,
Paul MTY, Yee BB, Zhang X, Alford EH, Pilapil BK and Gates BD,
Nanoscale
11
(4)
, 1937-1948
(2019),
The Royal Society of Chemistry.
|
| Abstract: The incorporation of catalytic nanocrystals into macroporous support materials has been very attractive due to their increased catalyst mass activity. This increase in catalytic efficiency is attributed in part to the increased surface area to volume ratio of the catalysts and the use of complementary support materials that can enhance their catalytic activity and stability. A uniform and tunable coating of nanocrystals on porous matrices can be difficult to achieve with some techniques such as electrodeposition. More sophisticated techniques for preparing uniform nanocrystal coatings include atomic layer deposition, but it can be difficult to reproduce these processes at commercial scales required for preparing catalyst materials. In this study, catalytic nanocrystals supported on three dimensional (3D) porous structures were prepared. The demonstrated technique utilized scalable approaches for achieving a uniform surface coverage of catalysts through the use of polymeric sacrificial templates. This template assisted technique was demonstrated with a good control over the surface coverage of catalysts, support material composition, and porosities of the support material. A series of regular porous supports were each prepared with a uniform coating of nanocrystals, such as NaYF4 nanocrystals supported by a porous 3D lattice of Ti1-xSixO2, Pt nanocrystals on a 3D porous support of TiO2, Pd nanocrystals on Ni nanobowls, and Pt nanocrystals on 3D assemblies of Au/TiO2 nanobowls. The template assisted preparation of high surface area macroporous supports could be further utilized for optimizing the use of catalytic materials in chemical, electrochemical, and photochemical reactions through increasing their catalytic efficiency and stability. |
BibTeX:
@article
{Paul2019,
title = {Template assisted preparation of high surface area macroporous supports with uniform and tunable nanocrystal loadings}
,author = {Paul, Michael T. Y. and Yee, Brenden B. and Zhang, Xin and Alford, Eiji H. and Pilapil, Brandy K. and Gates, Byron D.}
,journal = {Nanoscale}
,publisher = {The Royal Society of Chemistry}
,year = {2019}
,volume = {11}
,number = {4}
,pages = {1937--1948}
,url = {https://pubs.rsc.org/en/content/articlelanding/2019/nr/c8nr07762b}
,doi = {10.1039/C8NR07762B}
}
|
Size-Selective Exclusion Effects of Liquid Crystalline Tactoids on Nanoparticles: A Separation Method,
Wang P-X, Hamad WY and MacLachlan MJ,
Angewandte Chemie International Edition
57
(13)
, 3360-3365
(2018),
|
| Abstract: Liquid crystalline tactoids are anisotropic microdroplets existing in isotropic phases. We studied the structure and evolution of tactoids in the presence of doping nanoparticles by electron microscopy at the resolution of individual mesogens and observed size-selective exclusion effects of liquid crystalline tactoids on foreign nanoparticles. We applied this principle to the separation of polymer nanospheres, gold nanoparticles, and magnetic nanoparticles by size. These results indicate a new way to size-selectively separate nanoparticles using lyotropic liquid crystals, in which nanoparticles smaller than a threshold size will be selectively transferred from the disordered phase into the ordered phase by tactoids during the phase separation process. |
BibTeX:
@article
{Wang2018,
title = {Size-Selective Exclusion Effects of Liquid Crystalline Tactoids on Nanoparticles: A Separation Method}
,author = {Wang, Pei-Xi and Hamad, Wadood Y. and MacLachlan, Mark J.}
,journal = {Angewandte Chemie International Edition}
,year = {2018}
,volume = {57}
,number = {13}
,pages = {3360--3365}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.201712158}
,doi = {10.1002/anie.201712158}
}
|
Viscosity of erythritol and erythritol-water particles as a function of water activity: new results and an intercomparison of techniques for measuring the viscosity of particles,
Chu Y, Evoy E, Kamal S, Song YC, Reid JP, Chan CK and Bertram AK,
Atmospheric Measurement Techniques
11
(8)
, 4809-4822
(2018),
Copernicus Gesellschaft mbH.
|
| Abstract: A previous study reported an uncertainty of up to 3 orders of magnitude for the viscosity of erythritol (1,2,3,4-butanetetrol)-water particles. To help reduce the uncertainty in the viscosity of these particles, we measured the diffusion coefficient of a large organic dye (rhodamine B isothiocyanate-dextran, average molecular weight ∼ 70 000 g mol-1) in an erythritol-water matrix as a function of water activity using rectangular-area fluorescence recovery after photobleaching (rFRAP). The diffusion coefficients were then converted to viscosities of erythritol-water particles using the Stokes-Einstein equation. In addition, we carried out new viscosity measurements of erythritol-water particles using aerosol optical tweezers. Based on the new experimental results and viscosities reported in the literature, we conclude the following: (1) the viscosity of pure erythritol is 184-73+122 Pa s (2 standard deviations); (2) the addition of a hydroxyl (OH) functional group to a linear C4 carbon backbone increases the viscosity on average by a factor of 27-5+6 (2 standard deviations); and (3) the increase in viscosity from the addition of one OH functional group to a linear C4 carbon backbone is not a strong function of the number of OH functional groups already present in the molecule up to the addition of three OH functional groups, but the increase in viscosity may be larger when the linear C4 carbon backbone already contains three OH functional groups. These results should help improve the understanding of the viscosity of secondary organic aerosol particles in the atmosphere. In addition, these results show that at water activity > 0.4 the rFRAP technique, aerosol optical tweezers technique, and bead-mobility technique give results in reasonable agreement if the uncertainties in the measurements are considered. At water activity < 0.4, the mean viscosity values determined by the optical tweezers technique were higher than those determined by the bead-mobility and rFRAP techniques by 1-2 orders of magnitude. Nevertheless, the disagreement in viscosity measured using multiple techniques reported in this paper is smaller than reported previously. |
BibTeX:
@article
{Chu2018,
title = {Viscosity of erythritol and erythritol-water particles as a function of water activity: new results and an intercomparison of techniques for measuring the viscosity of particles}
,author = {Chu, Yangxi and Evoy, Erin and Kamal, Saeid and Song, Young Chul and Reid, Jonathan P. and Chan, Chak K. and Bertram, Allan K.}
,journal = {Atmospheric Measurement Techniques}
,publisher = {Copernicus Gesellschaft mbH}
,year = {2018}
,volume = {11}
,number = {8}
,pages = {4809--4822}
,doi = {10.5194/amt-11-4809-2018}
}
|
High-resolution broadband sum frequency generation vibrational spectroscopy using intrapulse interference,
Wang Y, Ma X, Wang H, Chen D, Chou KC and Li Q,
Physical Chemistry Chemical Physics
20
(32)
, 20752-20755
(2018),
The Royal Society of Chemistry.
|
| Abstract: We theoretically propose a new approach to obtain high-spectral-resolution sum frequency generation (SFG) vibrational spectra using intrapulse interference. By introducing a p-step phase modulation to the broadband 800 nm pulse, the broadband 800 nm laser pulse splits into two distinguishable pulses in the time domain with a fixed time delay. The resolution of the intrapulse interference SFG can be better than 1 cm-1 and is limited only by the spectral resolution of the spectrometer. This approach can accurately retrieve the amplitude and the relative phase of vibrational peaks. Additionally, the sensitivity of SFG is enhanced by adopting femtosecond IR and femtosecond visible pulses. |
BibTeX:
@article
{Wang2018a,
title = {High-resolution broadband sum frequency generation vibrational spectroscopy using intrapulse interference}
,author = {Wang, Yang and Ma, Xiangyun and Wang, Huijie and Chen, Da and Chou, Keng C. and Li, Qifeng}
,journal = {Physical Chemistry Chemical Physics}
,publisher = {The Royal Society of Chemistry}
,year = {2018}
,volume = {20}
,number = {32}
,pages = {20752--20755}
,url = {https://pubs.rsc.org/en/content/articlelanding/2018/cp/c8cp02519c}
,doi = {10.1039/C8CP02519C}
}
|
Thermochromic Solid-State Emission of Dipyridyl Sulfoxide Cu(I) Complexes,
Brown CM, Carta V and Wolf MO,
Chemistry of Materials
30
(16)
, 5786-5795
(2018),
American Chemical Society.
|
| Abstract: Copper(I) complexes (Cu-DPSO and Cu-Me-DPSO) utilizing sulfoxide-bridged dipyridyl ligands are reported. Cu-DPSO demonstrates photophysical properties typical with [Cu(disphosphine)(diimine)]+ complexes, however with additional steric bulk in the 6- and 6′-positions of the diimine ligand to give complex Cu-Me-DPSO; the photophysics are greatly altered. This species is isolated as an amorphous powder (a-Cu-Me-DPSO) which emits yellow light; upon heating to 180 °C, a crystalline powder is formed (c-Cu-Me-DPSO) which shows a large bathochromic shift (textgreater100 nm) in emission, and shows orange luminescence attributed to a flattening distortion of the complex away from a tetrahedral geometry. On cooling to -196 °C, c-Cu-Me-DPSO displays a reversible thermochromic solid-state emission, from orange at room temperature to yellow at low temperatures. Using solid-state variable temperature excitation and absorption data, this phenomenon is attributed to a change in coordination geometry about the copper atom in the excited state. At low temperatures, a pseudo-tetrahedral geometry is preferred, giving higher energy emission, whereas, at higher temperatures, a flattened geometry dominates, giving a lower energy emission under UV irradiation. This is a unique example of a monometallic copper(I) complex capable of reversible thermochromic emission in the solid state, and highlights the impact that subtle ligand tuning plays on the photophysical properties. Previous copper(I) thermochromic materials were limited to copper halide clusters, and this study opens new avenues toward highly functionalized, thermal stimuli-responsive materials. |
BibTeX:
@article
{Brown2018,
title = {Thermochromic Solid-State Emission of Dipyridyl Sulfoxide Cu(I) Complexes}
,author = {Brown, Christopher M. and Carta, Veronica and Wolf, Michael O.}
,journal = {Chemistry of Materials}
,publisher = {American Chemical Society}
,year = {2018}
,volume = {30}
,number = {16}
,pages = {5786--5795}
,url = {https://doi.org/10.1021/acs.chemmater.8b02821}
,doi = {10.1021/acs.chemmater.8b02821}
}
|
Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition,
DeRieux W-SW, Li Y, Lin P, Laskin J, Laskin A, Bertram AK, Nizkorodov SA and Shiraiwa M,
Atmospheric Chemistry and Physics (Online)
18
(9)
(2018),
European Geosciences Union.
|
| Abstract: The U.S. Department of Energy’s Office of Scientific and Technical Information |
BibTeX:
@article
{DeRieux2018,
title = {Predicting the glass transition temperature and viscosity of secondary organic material using molecular composition}
,author = {DeRieux, Wing-Sy Wong and Li, Ying and Lin, Peng and Laskin, Julia and Laskin, Alexander and Bertram, Allan K. and Nizkorodov, Sergey A. and Shiraiwa, Manabu}
,journal = {Atmospheric Chemistry and Physics (Online)}
,publisher = {European Geosciences Union}
,year = {2018}
,volume = {18}
,number = {9}
,url = {https://www.osti.gov/pages/biblio/1501916-predicting-glass-transition-temperature-viscosity-secondary-organic-material-using-molecular-composition}
,doi = {10.5194/acp-18-6331-2018}
}
|
The viscosity of atmospherically relevant organic particles,
Reid JP, Bertram AK, Topping DO, Laskin A, Martin ST, Petters MD, Pope FD and Rovelli G,
Nature Communications
9
(1)
, 956
(2018),
Nature Publishing Group.
|
| Abstract: The importance of organic aerosol particles in the environment has been long established, influencing cloud formation and lifetime, absorbing and scattering sunlight, affecting atmospheric composition and impacting on human health. Conventionally, ambient organic particles were considered to exist as liquids. Recent observations in field measurements and studies in the laboratory suggest that they may instead exist as highly viscous semi-solids or amorphous glassy solids under certain conditions, with important implications for atmospheric chemistry, climate and air quality. This review explores our understanding of aerosol particle phase, particularly as identified by measurements of the viscosity of organic particles, and the atmospheric implications of phase state. |
BibTeX:
@article
{Reid2018,
title = {The viscosity of atmospherically relevant organic particles}
,author = {Reid, Jonathan P. and Bertram, Allan K. and Topping, David O. and Laskin, Alexander and Martin, Scot T. and Petters, Markus D. and Pope, Francis D. and Rovelli, Grazia}
,journal = {Nature Communications}
,publisher = {Nature Publishing Group}
,year = {2018}
,volume = {9}
,number = {1}
,pages = {956}
,url = {https://www.nature.com/articles/s41467-018-03027-z}
,doi = {10.1038/s41467-018-03027-z}
}
|
Synthesis of Lithium Niobate Nanocrystals with Size Focusing through an Ostwald Ripening Process,
Ali RF and Gates BD,
Chemistry of Materials
30
(6)
, 2028-2035
(2018),
American Chemical Society.
|
| Abstract: A simple surfactant assisted solution-phase approach is demonstrated here for the preparation of lithium niobate (LiNbO3) nanoparticles with an average size of 30 nm. This solution-phase process results in the formation of crystalline, uniform nanoparticles of LiNbO3 at 220 °C with an optimal reaction time of 36 h. Advantages of this method also include the preparation of crystalline nanoparticles of LiNbO3 without the need for further heat treatment or the use of an inert atmosphere. The growth of these nanoparticles began with a controlled agglomeration of nuclei. The reaction subsequently underwent a process of oriented attachment and Ostwald ripening, which dominated and controlled the further growth of the nanoparticles. These processes produced single-crystalline nanoparticles of LiNbO3. The average dimensions of the nanoparticles were tuned from 30 to 95 nm by increasing the reaction time of the solvothermal process. The LiNbO3 nanoparticles were characterized using transmission electron microscopy (TEM), selected area electron diffraction (SAED), high resolution TEM, X-ray diffraction, and Raman spectroscopy techniques. The nanoparticles were also confirmed to be optically active for second harmonic generation (SHG). These particles could enable further development of SHG based microscopy techniques. |
BibTeX:
@article
{Ali2018,
title = {Synthesis of Lithium Niobate Nanocrystals with Size Focusing through an Ostwald Ripening Process}
,author = {Ali, Rana Faryad and Gates, Byron D.}
,journal = {Chemistry of Materials}
,publisher = {American Chemical Society}
,year = {2018}
,volume = {30}
,number = {6}
,pages = {2028--2035}
,url = {https://doi.org/10.1021/acs.chemmater.7b05282}
,doi = {10.1021/acs.chemmater.7b05282}
}
|
Thiol-Ligand-Catalyzed Quenching and Etching in Mixtures of Colloidal Quantum Dots and Silver Nanoparticles,
Lee J-S, Kim H and Algar WR,
The Journal of Physical Chemistry C
121
(51)
, 28566-28575
(2017),
American Chemical Society.
|
| Abstract: Plasmonic nanostructures have the potential to enhance the emissive properties of semiconductor quantum dots (QDs). Although gold nanoparticles have been widely used for this purpose, other metals, such as silver, are also of interest and have more desirable plasmonic properties; however, silver nanoparticles suffer from chemical instability that gold nanoparticles do not. We find that this instability has the potential to limit the integration of silver nanoparticles (AgNPs) with QDs. Specifically, the common selection of thiol ligands for colloidal stabilization of QDs is incompatible with AgNPs, whether silver nanospheres or silver nanoplates. Equilibrium desorption of thiol ligands from QDs drives a pseudocatalytic process wherein the AgNPs are etched to produce silver(I)–ligand complexes, which then undergo cation exchange reactions at the QD leading to quenching of its photoluminescence (PL) through the introduction of long-lived trap states. We characterize this process through a combination of morphological, chemical, and steady-state and time-resolved spectroscopic measurements. The latter include extinction and absorption, PL emission intensity and lifetime, and transient absorption. Importantly, the etching and quenching process is avoided with QDs that are coated with an amphiphilic polymer instead of thiol ligands. |
BibTeX:
@article
{Lee2017,
title = {Thiol-Ligand-Catalyzed Quenching and Etching in Mixtures of Colloidal Quantum Dots and Silver Nanoparticles}
,author = {Lee, Jae-Seung and Kim, Hyungki and Algar, W. Russ}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2017}
,volume = {121}
,number = {51}
,pages = {28566--28575}
,url = {https://doi.org/10.1021/acs.jpcc.7b10381}
,doi = {10.1021/acs.jpcc.7b10381}
}
|
Tunable Emission of Iridium(III) Complexes Bearing Sulfur-Bridged Dipyridyl Ligands,
Brown CM, Kitt MJ, Xu Z, Hean D, Ezhova MB and Wolf MO,
Inorganic Chemistry
56
(24)
, 15110-15118
(2017),
American Chemical Society.
|
| Abstract: A series of six new cyclometalated iridium(III) complexes [Ir(ppy)2(N?N)][PF6] (ppy = 2-phenylpyridine) is reported herein. Proligands bis(pyridin-2-yl)sulfane (1a), 2,2′-sulfinyldipyridine (1b), 2,2′-sulfonyldipyridine (1c), bis(4-methylpyridin-2-yl)sulfane (2a), 2,2′-sulfinylbis(4-methylpyridine) (2b), and 2,2′-sulfonylbis(4-methylpyridine) (2c) were synthesized, characterized, and employed as the N?N ancillary ligand. Changing the oxidation state of the sulfur atom serves as a switch to alter the emissive state from that of mainly 3LC character (blue-green emission) to one of 3MLCT/3LLCT character (yellow emission). Sulfide and sulfoxide complexes Ir(1a), Ir(1b), Ir(2a), and Ir(2b) show identical, vibrationally structured emission profiles with maxima at 478, 510, 548 nm in CH2Cl2 solutions resulting from a 3LC state. In contrast, sulfone complexes Ir(1c) and Ir(2c) show broad, red-shifted 3CT emission (552 and 537 nm, respectively). |
BibTeX:
@article
{Brown2017,
title = {Tunable Emission of Iridium(III) Complexes Bearing Sulfur-Bridged Dipyridyl Ligands}
,author = {Brown, Christopher M. and Kitt, Mitchell J. and Xu, Zhen and Hean, Duane and Ezhova, Maria B. and Wolf, Michael O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2017}
,volume = {56}
,number = {24}
,pages = {15110--15118}
,url = {https://doi.org/10.1021/acs.inorgchem.7b02439}
,doi = {10.1021/acs.inorgchem.7b02439}
}
|
Poly(p-phenylenediethynylene phosphine)s and Related p-Conjugated Phosphine–Diyne Polymers: Synthesis, Characterization and Photophysical Properties,
Rawe BW, Scott MR, Brown CM, MacKenzie HK and Gates DP,
Macromolecules
50
(22)
, 8916-8927
(2017),
American Chemical Society.
|
| Abstract: Despite the considerable synthetic challenge, polymers that incorporate phosphorus atoms within or adjacent to a p-conjugated backbone framework are of interest due to the ability to modulate the photophysical properties of the polymer based on the chemical environment at phosphorus. We report the synthesis and characterization of poly(p-phenylenediethlynylene phosphine)s, 1a–1e, a new class of s–p conjugated polymer. Polymers 1a–1e were prepared by a Ni-catalyzed coupling of dialkynes with phenyldichlorophosphine in the presence of excess triethylamine and have molecular weights (Mw) up to 12,000 g mol–1 (vs. polystyrene). While the polymers 1b–1e are nonfluorescent, blue fluorescence is observed upon oxidation of the phosphorus centers (Fsoln = 0.12–0.28). Polymers 1b·O–1e·O also exhibit yellow/green fluorescence in the solid state (Fsolid = 0.04–0.08). These results introduce a fascinating new class of main group-containing macromolecule and lay the groundwork for their utilization in sensory applications and/or their incorporation into optoelectrical devices. |
BibTeX:
@article
{Rawe2017,
title = {Poly(p-phenylenediethynylene phosphine)s and Related p-Conjugated Phosphine–Diyne Polymers: Synthesis, Characterization and Photophysical Properties}
,author = {Rawe, Benjamin W. and Scott, Michael R. and Brown, Christopher M. and MacKenzie, Harvey K. and Gates, Derek P.}
,journal = {Macromolecules}
,publisher = {American Chemical Society}
,year = {2017}
,volume = {50}
,number = {22}
,pages = {8916--8927}
,url = {https://doi.org/10.1021/acs.macromol.7b01933}
,doi = {10.1021/acs.macromol.7b01933}
}
|
Mixing times of organic molecules within secondary organic aerosol particles: a global planetary boundary layer perspective,
Maclean AM, Butenhoff CL, Grayson JW, Barsanti K, Jimenez JL and Bertram AK,
Atmospheric Chemistry and Physics
17
(21)
, 13037-13048
(2017),
Copernicus GmbH.
|
| Abstract: When simulating the formation and life cycle of secondary organic aerosol (SOA) with chemical transport models, it is often assumed that organic molecules are well mixed within SOA particles on the timescale of 1 h. While this assumption has been debated vigorously in the literature, the issue remains unresolved in part due to a lack of information on the mixing times within SOA particles as a function of both temperature and relative humidity. Using laboratory data, meteorological fields, and a chemical transport model, we estimated how often mixing times are < 1 h within SOA in the planetary boundary layer (PBL), the region of the atmosphere where SOA concentrations are on average the highest. First, a parameterization for viscosity as a function of temperature and RH was developed for a-pinene SOA using room-temperature and low-temperature viscosity data for a-pinene SOA generated in the laboratory using mass concentrations of 1000 µg m^-3. Based on this parameterization, the mixing times within a-pinene SOA are < 1 h for 98.5 % and 99.9 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant (total organic aerosol concentrations are > 0.5 µg m^-3 at the surface). Next, as a starting point to quantify how often mixing times of organic molecules are < 1 h within a-pinene SOA generated using low, atmospherically relevant mass concentrations, we developed a temperature-independent parameterization for viscosity using the room-temperature viscosity data for a-pinene SOA generated in the laboratory using a mass concentration of 70 µg m^-3. Based on this temperature-independent parameterization, mixing times within a-pinene SOA are < 1 h for 27 and 19.5 % of the occurrences in the PBL during January and July, respectively, when concentrations are significant. However, associated with these conclusions are several caveats, and due to these caveats we are unable to make strong conclusions about how often mixing times of organic molecules are < 1 h within a-pinene SOA generated using low, atmospherically relevant mass concentrations. Finally, a parameterization for viscosity of anthropogenic SOA as a function of temperature and RH was developed using sucrose–water data. Based on this parameterization, and assuming sucrose is a good proxy for anthropogenic SOA, 70 and 83 % of the mixing times within anthropogenic SOA in the PBL are < 1 h for January and July, respectively, when concentrations are significant. These percentages are likely lower limits due to the assumptions used to calculate mixing times. |
BibTeX:
@article
{Maclean2017,
title = {Mixing times of organic molecules within secondary organic aerosol particles: a global planetary boundary layer perspective}
,author = {Maclean, Adrian M. and Butenhoff, Christopher L. and Grayson, James W. and Barsanti, Kelley and Jimenez, Jose L. and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2017}
,volume = {17}
,number = {21}
,pages = {13037--13048}
,url = {https://www.atmos-chem-phys.net/17/13037/2017/}
,doi = {10.5194/acp-17-13037-2017}
}
|
Complex Formations between Surfactants and Polyelectrolytes of the Same Charge on a Water Surface,
Mafi A, Hu D and Chou KC,
Langmuir
33
(32)
, 7940-7946
(2017),
American Chemical Society.
|
| Abstract: The mechanism of complex formation between surfactants and polyelectrolytes with the same charge on the water surface was investigated using molecular dynamics simulations and phase-sensitive sum-frequency generation vibrational spectroscopy. Although complex formation between highly charged surfactants and polyelectrolytes of the same charge is generally expected to be prohibited by the electrostatic repulsive force, our study shows that it is possible to form thermodynamically stable complexes when excess ions are present in the solution. We found that anionic partially hydrolyzed polyacrylamide (HPAM) could interact with anionic sodium dodecyl sulfate (SDS) on a water surface in the presence of salts. With excess Na+ ions in the solution, the charge screening effect allows HPAM to weakly interact with SDS via hydrogen bonds. In the presence of divalent Ca2+ ions, the surfactant and the polymer are strongly coupled by forming Ca2+ ion bridges and hydrogen bonds. Our calculation shows that the presence of Ca2+ ions creates a steep binding energy of 30 kJ/mol near the water surface. These results were qualitatively verified using phase-sensitive sum-frequency generation vibrational spectroscopy. |
BibTeX:
@article
{Mafi2017,
title = {Complex Formations between Surfactants and Polyelectrolytes of the Same Charge on a Water Surface}
,author = {Mafi, Amirhossein and Hu, Dan and Chou, Keng C.}
,journal = {Langmuir}
,publisher = {American Chemical Society}
,year = {2017}
,volume = {33}
,number = {32}
,pages = {7940--7946}
,url = {https://doi.org/10.1021/acs.langmuir.7b01246}
,doi = {10.1021/acs.langmuir.7b01246}
}
|
A C-Pyrenyl Poly(methylenephosphine): Oxidation “Turns On” Blue Photoluminescence in Solution and the Solid State,
Rawe BW, Brown CM, MacKinnon MR, Patrick BO, Bodwell GJ and Gates DP,
Organometallics
36
(14)
, 2520-2526
(2017),
American Chemical Society.
|
| Abstract: A C-pyrenyl poly(methylenephosphine) (Mn = 4800, Ð = 1.56) was synthesized from the anionic polymerization of a P-mesityl phosphaalkene. The phosphine oxide polymer exhibits blue fluorescence in solution (?max 379, 400 nm, ?onset 560 nm; F = 0.05) and blue-green fluorescence in the solid state at room temperature (?max 460 nm, F = 0.07). In contrast, unoxidized polymer displays only a weak emission in solution and no emission in the solid state. Fluorescence studies of partially oxidized polymers (50, 75, 83% oxidation) indicate that “turn on” emission occurs only at very high degrees of oxidation (near 100. We conclude that even a small number of unoxidized phosphine moieties within the partially oxidized polymer intramolecularly quench the fluorescence. |
BibTeX:
@article
{Rawe2017a,
title = {A C-Pyrenyl Poly(methylenephosphine): Oxidation “Turns On” Blue Photoluminescence in Solution and the Solid State}
,author = {Rawe, Benjamin W. and Brown, Christopher M. and MacKinnon, Marc R. and Patrick, Brian O. and Bodwell, Graham J. and Gates, Derek P.}
,journal = {Organometallics}
,publisher = {American Chemical Society}
,year = {2017}
,volume = {36}
,number = {14}
,pages = {2520--2526}
,url = {https://doi.org/10.1021/acs.organomet.6b00880}
,doi = {10.1021/acs.organomet.6b00880}
}
|
The effect of hydroxyl functional groups and molar mass on the viscosity of non-crystalline organic and organic–water particles,
Grayson JW, Evoy E, Song M, Chu Y, Maclean AM, Nguyen A, Upshur MA, Ebrahimi M, Chan CK, Geiger FM, Thomson RJ and Bertram AK,
Atmospheric Chemistry and Physics
17
(13)
, 8509-8524
(2017),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater The viscosities of three polyols and three saccharides, all in the non-crystalline state, have been studied. Two of the polyols (2-methyl-1,4-butanediol and 1,2,3-butanetriol) were studied under dry conditions, the third (1,2,3,4-butanetetrol) was studied as a function of relative humidity (RH), including under dry conditions, and the saccharides (glucose, raffinose, and maltohexaose) were studied as a function of RH. The mean viscosities of the polyols under dry conditions range from 1.5 × 10^-1 to 3.7 × 10^1 Pa s, with the highest viscosity being that of the tetrol. Using a combination of data determined experimentally here and literature data for alkanes, alcohols, and polyols with a C_3 to C_6 carbon backbone, we show (1) there is a near-linear relationship between log_10 (viscosity) and the number of hydroxyl groups in the molecule, (2) that on average the addition of one OH group increases the viscosity by a factor of approximately 22 to 45, (3) the sensitivity of viscosity to the addition of one OH group is not a strong function of the number of OH functional groups already present in the molecule up to three OH groups, and (4) higher sensitivities are observed when the molecule has more than three OH groups. Viscosities reported here for 1,2,3,4-butanetetrol particles are lower than previously reported measurements using aerosol optical tweezers, and additional studies are required to resolve these discrepancies. For saccharide particles at 30 % RH, viscosity increases by approximately 2–5 orders of magnitude as molar mass increases from 180 to 342 g mol^-1, and at 80 % RH, viscosity increases by approximately 4–5 orders of magnitude as molar mass increases from 180 to 991 g mol^-1. These results suggest oligomerization of highly oxidized compounds in atmospheric secondary organic aerosol (SOA) could lead to large increases in viscosity, and may be at least partially responsible for the high viscosities observed in some SOA. Finally, two quantitative structure–property relationship models (Sastri and Rao, 1992; Marrero-Morejón and Pardillo-Fontdevila, 2000) were used to predict the viscosity of alkanes, alcohols, and polyols with a C_3–C_6 carbon backbone. Both models show reasonably good agreement with measured viscosities for the alkanes, alcohols, and polyols studied here except for the case of a hexol, the viscosity of which is underpredicted by 1–3 orders of magnitude by each of the models.textless/ptextgreater |
BibTeX:
@article
{Grayson2017,
title = {The effect of hydroxyl functional groups and molar mass on the viscosity of non-crystalline organic and organic–water particles}
,author = {Grayson, James W. and Evoy, Erin and Song, Mijung and Chu, Yangxi and Maclean, Adrian M. and Nguyen, Allena and Upshur, Mary Alice and Ebrahimi, Marzieh and Chan, Chak K. and Geiger, Franz M. and Thomson, Regan J. and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2017}
,volume = {17}
,number = {13}
,pages = {8509--8524}
,url = {https://www.atmos-chem-phys.net/17/8509/2017/}
,doi = {10.5194/acp-17-8509-2017}
}
|
Fabrication of Micro/Nano Patterns on Polymeric Substrates Using Laser Ablation Methods to Control Wettability Behaviour: A Critical Review,
Toosi SF, Moradi S and Hatzikiriakos SG,
Reviews of Adhesion and Adhesives
5
(1)
, 55-78
(2017),
|
| Abstract: The fabrication of micro/nano patterned surfaces using femtosecond laser micromachining technique has emerged in recent years as a new method. This is due to its applicability to virtually all kinds of materials in an easy one-step process, which is scalable. Here we present a review of the effects of femtosecond laser ablation process parameters such as laser fluence, scan speed, and beam overlap on the fabricated patterns on various polymeric materials: PTFE, PLA, PMMA, PDMS, and medical grade-PVC. In addition, it presents the physical and chemical properties of fabricated microchannels. SEM, XPS, profilometry, and water contact angle measurments are used to characterize the surface chemical, morphological, and wetting properties. The surface morphology and thus the wetting properties can be altered by tuning the laser parameters. By introducing micro/nano roughness to the surface of hydrophobic polymers, extreme water repellency and superhydrophobicity is developed. Various applications of these fabricated superhydrophobic substrates in biomedical, packaging, fuel cells, low friction, self-cleaning are also discussed to a certain extent. Surfaces with superhydrophobic properties are mainly obtained by a combination of appropriate morphology at micro- and/or nanoscale and low surface energy material. |
BibTeX:
@article
{Toosi2017,
title = {Fabrication of Micro/Nano Patterns on Polymeric Substrates Using Laser Ablation Methods to Control Wettability Behaviour: A Critical Review}
,author = {Toosi, Salma Falah and Moradi, Sona and Hatzikiriakos, Savvas G.}
,journal = {Reviews of Adhesion and Adhesives}
,year = {2017}
,volume = {5}
,number = {1}
,pages = {55--78}
,doi = {10.7569/RAA.2017.097302}
}
|
Development of highly sensitive ZnO/In2O3 composite gas sensor activated by UV-LED,
Espid E and Taghipour F,
Sensors and Actuators B: Chemical
241
, 828-839
(2017),
|
| Abstract: The photo-responsive behavior of ZnO/In2O3 composite sensors was investigated for detecting low concentrations of NO2 gas under 365nm UV-LED irradiation at room temperature. The composite samples were prepared by the co-precipitation method with the appropriate components ratio to obtain superior sensing performance. The composition, structure, and optical properties of the synthesized sensing materials were characterized by EDS, XRD, SEM, XPS and UV–vis analyses. In terms of gas sensing performance, the synergistic effects of combined materials led to an enhanced response of the composite sensors, compared to those of pristine ZnO and In2O3 sensors under UV illumination. The considerable improvement in sensor response was attributed to the ZnO role in charge carrier mobility enhancement and low recombination rate of active charge carriers, as well as In2O3 contributions as radiation absorption centers and chemisorption promoters in the composite structure. It was found that the response of the composite gas sensor is largely dependent on the UV irradiance in which increasing the UV flux reduced the response, but shortened the response time. |
BibTeX:
@article
{Espid2017,
title = {Development of highly sensitive ZnO/In2O3 composite gas sensor activated by UV-LED}
,author = {Espid, Ehsan and Taghipour, Fariborz}
,journal = {Sensors and Actuators B: Chemical}
,year = {2017}
,volume = {241}
,pages = {828--839}
,url = {http://www.sciencedirect.com/science/article/pii/S0925400516317592}
,doi = {10.1016/j.snb.2016.10.129}
}
|
Diffusion coefficients of organic molecules in sucrose–water solutions and comparison with Stokes–Einstein predictions,
Chenyakin Y, Ullmann DA, Evoy E, Renbaum-Wolff L, Kamal S and Bertram AK,
Atmospheric Chemistry and Physics
17
(3)
, 2423-2435
(2017),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater The diffusion coefficients of organic species in secondary organic aerosol (SOA) particles are needed to predict the growth and reactivity of these particles in the atmosphere. Previously, viscosity measurements, along with the Stokes–Einstein relation, have been used to estimate the diffusion rates of organics within SOA particles or proxies of SOA particles. To test the Stokes–Einstein relation, we have measured the diffusion coefficients of three fluorescent organic dyes (fluorescein, rhodamine 6G and calcein) within sucrose–water solutions with varying water activity. Sucrose–water solutions were used as a proxy for SOA material found in the atmosphere. Diffusion coefficients were measured using fluorescence recovery after photobleaching. For the three dyes studied, the diffusion coefficients vary by 4–5 orders of magnitude as the water activity varied from 0.38 to 0.80, illustrating the sensitivity of the diffusion coefficients to the water content in the matrix. At the lowest water activity studied (0.38), the average diffusion coefficients were 1.9 × 10^-13, 1.5 × 10^-14 and 7.7 × 10^-14 cm^2 s^-1 for fluorescein, rhodamine 6G and calcein, respectively. The measured diffusion coefficients were compared with predictions made using literature viscosities and the Stokes–Einstein relation. We found that at water activity = 0.6 (which corresponds to a viscosity of = 360 Pa s and T_g/T = 0.81), predicted diffusion rates agreed with measured diffusion rates within the experimental uncertainty (T_g represents the glass transition temperature and T is the temperature of the measurements). When the water activity was 0.38 (which corresponds to a viscosity of 3.3 × 10^6 Pa s and a T_g/T of 0.94), the Stokes–Einstein relation underpredicted the diffusion coefficients of fluorescein, rhodamine 6G and calcein by a factor of 118 (minimum of 10 and maximum of 977), a factor of 17 (minimum of 3 and maximum of 104) and a factor of 70 (minimum of 8 and maximum of 494), respectively. This disagreement is significantly smaller than the disagreement observed when comparing measured and predicted diffusion coefficients of water in sucrose–water mixtures.textless/ptextgreater |
BibTeX:
@article
{Chenyakin2017,
title = {Diffusion coefficients of organic molecules in sucrose–water solutions and comparison with Stokes–Einstein predictions}
,author = {Chenyakin, Yuri and Ullmann, Dagny A. and Evoy, Erin and Renbaum-Wolff, Lindsay and Kamal, Saeid and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2017}
,volume = {17}
,number = {3}
,pages = {2423--2435}
,url = {https://www.atmos-chem-phys.net/17/2423/2017/}
,doi = {10.5194/acp-17-2423-2017}
}
|
Experimental Demonstration of Coherent Control in Quantum Chaotic Systems,
Bitter M and Milner V,
Physical Review Letters
118
(3)
, 034101
(2017),
American Physical Society.
|
| Abstract: We experimentally demonstrate coherent control of a quantum system, whose dynamics is chaotic in the classical limit. Interaction of diatomic molecules with a periodic sequence of ultrashort laser pulses leads to the dynamical localization of the molecular angular momentum, a characteristic feature of the chaotic quantum kicked rotor. By changing the phases of the rotational states in the initially prepared coherent wave packet, we control the rotational distribution of the final localized state and its total energy. We demonstrate the anticipated sensitivity of control to the exact parameters of the kicking field, as well as its disappearance in the classical regime of excitation. |
BibTeX:
@article
{Bitter2017,
title = {Experimental Demonstration of Coherent Control in Quantum Chaotic Systems}
,author = {Bitter, Martin and Milner, Valery}
,journal = {Physical Review Letters}
,publisher = {American Physical Society}
,year = {2017}
,volume = {118}
,number = {3}
,pages = {034101}
,url = {https://link.aps.org/doi/10.1103/PhysRevLett.118.034101}
,doi = {10.1103/PhysRevLett.118.034101}
}
|
Control of quantum localization and classical diffusion in laser-kicked molecular rotors,
Bitter M and Milner V,
Physical Review A
95
(1)
, 013401
(2017),
American Physical Society.
|
| Abstract: We experimentally study a system of quantum kicked rotors—an ensemble of diatomic molecules exposed to a periodic sequence of ultrashort laser pulses. In the regime where the underlying classical dynamics is chaotic, we investigate the quantum phenomenon of dynamical localization by means of state-resolved coherent Raman spectroscopy. We examine the dependence of the exponentially localized angular momentum distribution and of the total rotational energy on the time period between the pulses and their amplitude. The former parameter is shown to provide control over the localization center, whereas the latter one controls the localization length. Similar control of the center and width of a nonlocalized rotational distribution is demonstrated in the limit of classical diffusion, established by adding noise to the periodic pulse sequence. |
BibTeX:
@article
{Bitter2017a,
title = {Control of quantum localization and classical diffusion in laser-kicked molecular rotors}
,author = {Bitter, Martin and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2017}
,volume = {95}
,number = {1}
,pages = {013401}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.95.013401}
,doi = {10.1103/PhysRevA.95.013401}
}
|
Single molecule localization deep within thick cells; a novel super-resolution microscope,
Tafteh R, Scriven DRL, Moore EDW and Chou KC,
Journal of Biophotonics
9
(1-2)
, 155-160
(2016),
|
| Abstract: A novel 3D imaging system based on single-molecule localization microscopy is presented to allow high-accuracy drift-free (textless0.7 nm lateral; 2.5 nm axial) imaging many microns deep into a cell. When imaging deep within the cell, distortions of the point-spread function result in an inaccurate and very compressed Z distribution. For the system to accurately represent the position of each blink, a series of depth-dependent calibrations are required. The system and its allied methodology are applied to image the ryanodine receptor in the cardiac myocyte. Using the depth-dependent calibration, the receptors deep within the cell are spread over a Z range that is many hundreds of nanometers greater than implied by conventional analysis. We implemented a time domain filter to detect overlapping blinks that were not filtered by a stringent goodness of fit criterion. This filter enabled us to resolve the structure of the individual (30 nm square) receptors giving a result similar to that obtained with electron tomography. High-accuracy deep imaging of the ryanodine receptor in the cardiac myocyte, using single-molecule localization microscopy. Depth-dependent calibrations are performed for accurate depth localization. The optical design featuring two independent and variable focal planes allows real-time feedback for drift-free deep imaging. |
BibTeX:
@article
{Tafteh2016,
title = {Single molecule localization deep within thick cells; a novel super-resolution microscope}
,author = {Tafteh, Reza and Scriven, David R. L. and Moore, Edwin D. W. and Chou, Keng C.}
,journal = {Journal of Biophotonics}
,year = {2016}
,volume = {9}
,number = {1-2}
,pages = {155--160}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/jbio.201500140}
,doi = {10.1002/jbio.201500140}
}
|
Long-Lived, Emissive Excited States in Direct and Amide-Linked Thienyl-Substituted RuII Complexes,
Majewski MB, Smith JG, Wolf MO and Patrick BO,
European Journal of Inorganic Chemistry
2016
(10)
, 1443-1443
(2016),
|
| Abstract: Abstract Invited for the cover of this issue is the group of Michael Wolf at the University of British Columbia, Vancouver, Canada. The cover image shows the structures of four heteroleptic RuII complexes with thienyl groups coordinated to the metal center through 2,2′-bipyridine ligands via amide or C–C linkages. |
BibTeX:
@article
{Majewski2016,
title = {Long-Lived, Emissive Excited States in Direct and Amide-Linked Thienyl-Substituted RuII Complexes}
,author = {Majewski, Marek B. and Smith, Jeremy G. and Wolf, Michael O. and Patrick, Brian O.}
,journal = {European Journal of Inorganic Chemistry}
,year = {2016}
,volume = {2016}
,number = {10}
,pages = {1443-1443}
,url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/ejic.201600285}
,doi = {10.1002/ejic.201600285}
}
|
A long-wavelength quantum dot-concentric FRET configuration: characterization and application in a multiplexed hybridization assay,
Jun Li J and Algar WR,
Analyst
141
(12)
, 3636-3647
(2016),
Royal Society of Chemistry.
|
| Abstract: Quantum dot-based concentric Förster resonance energy transfer (cFRET) is a promising modality for the development of multifunctional fluorescent probes for bioanalysis and bioimaging. To date, the scope of cFRET has been largely limited to a prototypical configuration with a particular combination of quantum dot (QD) and fluorescent dyes linked through peptides. Expansion of the scope of cFRET is critical for its further development. Here, we expand the scope of cFRET in two capacities. First, we design and characterize a new long-wavelength cFRET configuration that combines red- and deep-red fluorescent dyes, Alexa Fluor 633 and Alexa Fluor 680, with an orange-emitting QD. Sequential and competitive energy transfer pathways are characterized through a rate analysis, where the balance of these rates more strongly favours competitive energy transfer in the new long-wavelength configuration versus sequential energy transfer in the previous prototypical configuration. Although the new cFRET configuration is more susceptible to photobleaching, its superior brightness and longer-wavelength excitation and emission provide an order of magnitude higher signal-to-background ratios in biological matrices (e.g., serum, blood) than the previous prototypical configuration. Second, we demonstrate that an oligonucleotide-linked, long-wavelength cFRET configuration has energy transfer similar to an analogous peptide-linked configuration, where the oligonucleotide-linked cFRET configuration can be combined with toehold-mediated strand displacement for the multiplexed detection of unlabeled nucleic acid targets as a single vector. Overall, this work establishes the general applicability of cFRET and introduces new strategies for its bioanalytical application. |
BibTeX:
@article
{Jun Li2016,
title = {A long-wavelength quantum dot-concentric FRET configuration: characterization and application in a multiplexed hybridization assay}
,author = {Jun Li, Jia and Algar, W. Russ}
,journal = {Analyst}
,publisher = {Royal Society of Chemistry}
,year = {2016}
,volume = {141}
,number = {12}
,pages = {3636--3647}
,url = {https://pubs.rsc.org/en/content/articlelanding/2016/an/c6an00492j}
,doi = {10.1039/C6AN00492J}
}
|
Real-time 3D stabilization of a super-resolution microscope using an electrically tunable lens,
Tafteh R, Abraham L, Seo D, Lu HY, Gold MR and Chou KC,
Optics Express
24
(20)
, 22959-22970
(2016),
Optical Society of America.
|
| Abstract: Single-molecule localization microscopy (SMLM) has become an essential tool for examining a wide variety of biological structures and processes. However, the relatively long acquisition time makes SMLM prone to drift-induced artifacts. Here we report an optical design with an electrically tunable lens (ETL) that actively stabilizes a SMLM in three dimensions and nearly eliminates the mechanical drift (RMS textasciitilde0.7 nm lateral and textasciitilde2.7 nm axial). The bifocal design that employed fiducial markers on the coverslip was able to stabilize the sample regardless of the imaging depth. The effectiveness of the ETL was demonstrated by imaging endosomal transferrin receptors near the apical surface of B-lymphocytes at a depth of 8 &x00B5;m. The drift-free images obtained with the stabilization system showed that the transferrin receptors were present in distinct but heterogeneous clusters with a bimodal size distribution. In contrast, the images obtained without the stabilization system showed a broader unimodal size distribution. Thus, this stabilization system enables a more accurate analysis of cluster topology. Additionally, this ETL-based stabilization system is cost-effective and can be integrated into existing microscopy systems. |
BibTeX:
@article
{Tafteh2016a,
title = {Real-time 3D stabilization of a super-resolution microscope using an electrically tunable lens}
,author = {Tafteh, Reza and Abraham, Libin and Seo, Denny and Lu, Henry Y. and Gold, Michael R. and Chou, Keng C.}
,journal = {Optics Express}
,publisher = {Optical Society of America}
,year = {2016}
,volume = {24}
,number = {20}
,pages = {22959--22970}
,url = {https://www.osapublishing.org/oe/abstract.cfm?uri=oe-24-20-22959}
,doi = {10.1364/OE.24.022959}
}
|
The effect of photocatalyst excited state lifetime on the rate of photoredox catalysis,
Ochola JR and Wolf MO,
Organic & Biomolecular Chemistry
14
(38)
, 9088-9092
(2016),
The Royal Society of Chemistry.
|
| Abstract: Four different iridium(III) polypyridyl complexes with varying excited state lifetimes are used as photocatalysts to study the effect of excited state lifetime on the rate of a prototypical photoredox-catalyzed reaction, the trifluoromethylation of quinoline. An improved mechanistic understanding of the photocatalysis is achieved, enabling guided optimization of reaction conditions and elucidating the role of the photocatalyst excited state lifetime on the rate of photocatalysis. |
BibTeX:
@article
{Ochola2016,
title = {The effect of photocatalyst excited state lifetime on the rate of photoredox catalysis}
,author = {Ochola, J. R. and Wolf, M. O.}
,journal = {Organic & Biomolecular Chemistry}
,publisher = {The Royal Society of Chemistry}
,year = {2016}
,volume = {14}
,number = {38}
,pages = {9088--9092}
,url = {https://pubs.rsc.org/en/content/articlelanding/2016/ob/c6ob01717g}
,doi = {10.1039/C6OB01717G}
}
|
Dual-Emissive Platinum(II) Metallacycles with Thiophene-Containing Bisacetylide Ligands,
Cao Y, Wolf MO and Patrick BO,
Inorganic Chemistry
55
(17)
, 8985-8993
(2016),
American Chemical Society.
|
| Abstract: Three cis-diphosphino Pt(II) metallacycles with thiophene-containing bisacetylide ligands were synthesized and their absorption and emission properties examined. These properties are explained by DFT and TD-DFT analysis of ground-state as well as singlet- and triplet-state energies and geometries. Two of the metallacycles show room-temperature dual emission (fluorescence and phosphorescence) with different intensity ratios. Replacing the phenylene or ethynylene groups with thiophene rings in the bisacetylide ligand of the metallacycles results in modulation of the S1 and T1 states to show stronger fluorescence and weaker phosphorescence. More rigid and planar metallacycles suffer less from energy loss due to smaller degrees of structural reorganization and thermal deactivation. These are important factors to consider when designing single-component dual-emissive materials for applications such as white-emitting OLEDs, self-referencing oxygen sensors, and hypoxia contrast agents. |
BibTeX:
@article
{Cao2016,
title = {Dual-Emissive Platinum(II) Metallacycles with Thiophene-Containing Bisacetylide Ligands}
,author = {Cao, Yang and Wolf, Michael O. and Patrick, Brian O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2016}
,volume = {55}
,number = {17}
,pages = {8985--8993}
,url = {https://doi.org/10.1021/acs.inorgchem.6b01464}
,doi = {10.1021/acs.inorgchem.6b01464}
}
|
Experimental Observation of Dynamical Localization in Laser-Kicked Molecular Rotors,
Bitter M and Milner V,
Physical Review Letters
117
(14)
, 144104
(2016),
American Physical Society.
|
| Abstract: The periodically kicked rotor is a paradigm system for studying quantum effects on classically chaotic dynamics. The wave function of the quantum rotor localizes in angular momentum space, similarly to Anderson localization of the electronic wave function in disordered solids. Here, we observe dynamical localization in a system of true quantum rotors by subjecting nitrogen molecules to periodic sequences of femtosecond pulses. Exponential distribution of the molecular angular momentum—the hallmark of dynamical localization—is measured directly by means of coherent Raman scattering. We demonstrate the suppressed rotational energy growth with the number of laser kicks and study the dependence of the localization length on the kick strength. Because of its quantum coherent nature, both timing and amplitude noise are shown to destroy the localization and revive the diffusive growth of energy. |
BibTeX:
@article
{Bitter2016b,
title = {Experimental Observation of Dynamical Localization in Laser-Kicked Molecular Rotors}
,author = {Bitter, Martin and Milner, Valery}
,journal = {Physical Review Letters}
,publisher = {American Physical Society}
,year = {2016}
,volume = {117}
,number = {14}
,pages = {144104}
,url = {https://link.aps.org/doi/10.1103/PhysRevLett.117.144104}
,doi = {10.1103/PhysRevLett.117.144104}
}
|
Self-Quenching, Dimerization, and Homo-FRET in Hetero-FRET Assemblies with Quantum Dot Donors and Multiple Dye Acceptors,
Conroy EM, Li JJ, Kim H and Algar WR,
The Journal of Physical Chemistry C
120
(31)
, 17817-17828
(2016),
American Chemical Society.
|
| Abstract: The combination of semiconductor quantum dots (QDs) and Förster resonance energy transfer (FRET) is a powerful tool for bioanalysis and imaging. Through FRET, the dye is able to borrow brightness from the QD, and the FRET efficiency can be tuned through the assembly of multiple acceptor dyes per QD. In principle, the fluorescence intensity from acceptor dyes assembled to a QD donor should always exceed that from the dyes alone, but we observed anomalously low acceptor dye fluorescence intensities in FRET systems with a QD donor and multiple Alexa Fluor 610 (A610) or Alexa Fluor 633 (A633) acceptors. In contrast, fluorescence from Alexa Fluor 555 (A555) or Alexa Fluor 647 (A647) acceptors was well-behaved and agreed with theoretical expectations. The difference between these systems was studied using a combination of UV–visible absorption and fluorescence intensity, lifetime, and anisotropy measurements. Anomalous fluorescence from A610 and A633 arose from the formation of nonfluorescent, H-type dimers of these dyes. The monomer–dimer equilibrium was shifted strongly in favor of the dimer as a result of the locally high concentration of dyes assembled to the QD. Both the lower number of monomeric dyes per QD and the introduction of a competitive energy transfer pathway from the QD to dimeric dyes contributed to the low dye fluorescence. Another consequence of the close proximity between the dyes was homo-FRET, which was particularly evident with A555 and A647 acceptors. Homo-FRET did not appear to lead to significant quenching of dye fluorescence, although there was some evidence of low-efficiency energy transfer to dyes that may act as modest energy sinks. The results of this study help inform the rational design of optimized QD–FRET probes for biological applications. |
BibTeX:
@article
{Conroy2016,
title = {Self-Quenching, Dimerization, and Homo-FRET in Hetero-FRET Assemblies with Quantum Dot Donors and Multiple Dye Acceptors}
,author = {Conroy, Erin M. and Li, Jia Jun and Kim, Hyungki and Algar, W. Russ}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2016}
,volume = {120}
,number = {31}
,pages = {17817--17828}
,url = {https://doi.org/10.1021/acs.jpcc.6b05886}
,doi = {10.1021/acs.jpcc.6b05886}
}
|
Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities,
Song M, Liu PF, Hanna SJ, Zaveri RA, Potter K, You Y, Martin ST and Bertram AK,
Atmospheric Chemistry and Physics
16
(14)
, 8817-8830
(2016),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater To improve predictions of air quality, visibility, and climate change, knowledge of the viscosities and diffusion rates within organic particulate matter consisting of secondary organic material (SOM) is required. Most qualitative and quantitative measurements of viscosity and diffusion rates within organic particulate matter have focused on SOM particles generated from biogenic volatile organic compounds (VOCs) such as a-pinene and isoprene. In this study, we quantify the relative humidity (RH)-dependent viscosities at 295 ± 1 K of SOM produced by photo-oxidation of toluene, an anthropogenic VOC. The viscosities of toluene-derived SOM were 2 × 10^-1 to 6 × 10^6 Pa s from 30 to 90 % RH, and greater than 2 × 10^8 Pa s (similar to or greater than the viscosity of tar pitch) for RH = 17 %. These viscosities correspond to Stokes–Einstein-equivalent diffusion coefficients for large organic molecules of 2 × 10^-15 cm^2 s^-1 for 30 % RH, and lower than 3 × 10^-17 cm^2 s^-1 for RH = 17 %. Based on these estimated diffusion coefficients, the mixing time of large organic molecules within 200 nm toluene-derived SOM particles is 0.1–5 h for 30 % RH, and higher than 100 h for RH = 17 %. As a starting point for understanding the mixing times of large organic molecules in organic particulate matter over cities, we applied the mixing times determined for toluene-derived SOM particles to the world’s top 15 most populous megacities. If the organic particulate matter in these megacities is similar to the toluene-derived SOM in this study, in Istanbul, Tokyo, Shanghai, and São Paulo, mixing times in organic particulate matter during certain periods of the year may be very short, and the particles may be well-mixed. On the other hand, the mixing times of large organic molecules in organic particulate matter in Beijing, Mexico City, Cairo, and Karachi may be long and the particles may not be well-mixed in the afternoon (15:00–17:00 LT) during certain times of the year.textless/ptextgreater |
BibTeX:
@article
{Song2016,
title = {Relative humidity-dependent viscosity of secondary organic material from toluene photo-oxidation and possible implications for organic particulate matter over megacities}
,author = {Song, Mijung and Liu, Pengfei F. and Hanna, Sarah J. and Zaveri, Rahul A. and Potter, Katie and You, Yuan and Martin, Scot T. and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2016}
,volume = {16}
,number = {14}
,pages = {8817--8830}
,url = {https://www.atmos-chem-phys.net/16/8817/2016/}
,doi = {10.5194/acp-16-8817-2016}
}
|
Effect of varying experimental conditions on the viscosity of a-pinene derived secondary organic material,
Grayson JW, Zhang Y, Mutzel A, Renbaum-Wolff L, Böge O, Kamal S, Herrmann H, Martin ST and Bertram AK,
Atmospheric Chemistry and Physics (Online)
16
(10)
(2016),
European Geosciences Union.
|
| Abstract: The U.S. Department of Energy’s Office of Scientific and Technical Information |
BibTeX:
@article
{Grayson2016,
title = {Effect of varying experimental conditions on the viscosity of a-pinene derived secondary organic material}
,author = {Grayson, James W. and Zhang, Yue and Mutzel, Anke and Renbaum-Wolff, Lindsay and Böge, Olaf and Kamal, Saeid and Herrmann, Hartmut and Martin, Scot T. and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics (Online)}
,publisher = {European Geosciences Union}
,year = {2016}
,volume = {16}
,number = {10}
,url = {https://www.osti.gov/pages/biblio/1375407-effect-varying-experimental-conditions-viscosity-pinene-derived-secondary-organic-material}
,doi = {10.5194/acp-16-6027-2016}
}
|
Revisiting the Thermodynamics of Water Surfaces and the Effects of Surfactant Head Group,
Hu D, Mafi A and Chou KC,
The Journal of Physical Chemistry B
120
(9)
, 2257-2261
(2016),
American Chemical Society.
|
| Abstract: It is common knowledge that surfactants lower the surface tension of water. The typical textbook explanation of this phenomenon is that the force of attraction between surfactant and water molecules is less than that between two water molecules; hence the surface contraction force decreases in the presence of surfactants; however, this common description, based on the strength of intermolecular interactions, is overly simplified because it ignores an important thermodynamic function: the surface entropy of water. Here we report separate measurements of water’s surface enthalpy and surface entropy in the presence of nonionic, zwitterionic, anionic, and cationic surfactants. While all of these surfactants decreased the surface enthalpy of water by 50–70 the surface entropy of water could drop to near-zero or even negative values for ionic surfactants. Studies of this zero-entropy state of water surface using phase-sensitive sum-frequency generation (SFG) vibrational spectroscopy and molecular dynamics (MD) simulations suggested that the zero-entropy state of the water surface was associated with surfactant-induced ordering of water molecules and enhanced hydrogen bond formation at the water surface. Both effects reduce water molecules’ degrees of freedom for motion and thus lower the surface entropy of water. The ability of a surfactant to decrease the surface entropy of water is in the order ionic textgreater zwitterionic textgreater nonionic. For all surfactant head groups surface entropy plays a critical role in determining the surface tension of water. The description of water’s surface tension is not complete without considering its surface entropy. |
BibTeX:
@article
{Hu2016,
title = {Revisiting the Thermodynamics of Water Surfaces and the Effects of Surfactant Head Group}
,author = {Hu, Dan and Mafi, Amirhossein and Chou, Keng C.}
,journal = {The Journal of Physical Chemistry B}
,publisher = {American Chemical Society}
,year = {2016}
,volume = {120}
,number = {9}
,pages = {2257--2261}
,url = {https://doi.org/10.1021/acs.jpcb.5b11717}
,doi = {10.1021/acs.jpcb.5b11717}
}
|
Effect of viscosity on photodegradation rates in complex secondary organic aerosol materials,
Hinks ML, Brady MV, Lignell H, Song M, Grayson JW, Bertram AK, Lin P, Laskin A, Laskin J and Nizkorodov SA,
Physical Chemistry Chemical Physics
18
(13)
, 8785-8793
(2016),
The Royal Society of Chemistry.
|
| Abstract: This work explores the effect of environmental conditions on the photodegradation rates of atmospherically relevant, photolabile, organic molecules embedded in a film of secondary organic material (SOM). Three types of SOM were studied: a-pinene/O3 SOM (PSOM), limonene/O3 SOM (LSOM), and aged limonene/O3 obtained by exposure of LSOM to ammonia (brown LSOM). PSOM and LSOM were impregnated with 2,4-dinitrophenol (2,4-DNP), an atmospherically relevant molecule that photodegrades faster than either PSOM or LSOM alone, to serve as a probe of SOM matrix effects on photochemistry. Brown LSOM contains an unidentified chromophore that absorbs strongly at 510 nm and photobleaches upon irradiation. This chromophore served as a probe molecule for the brown LSOM experiments. In all experiments, either the temperature or relative humidity (RH) surrounding the SOM films was varied. The extent of photochemical reaction in the samples was monitored using UV-vis absorption spectroscopy. For all three model systems examined, the observed photodegradation rates were slower at lower temperatures and lower RH, conditions that make SOM more viscous. Additionally, the activation energies for photodegradation of each system were positively correlated with the viscosity of the SOM matrix as measured in poke-flow experiments. These activation energies were calculated to be 50, 24, and 17 kJ mol-1 for 2,4-DNP in PSOM, 2,4-DNP in LSOM, and the chromophore in brown LSOM, respectively, and PSOM was found to be the most viscous of the three. These results suggest that the increased viscosity is hindering the motion of the molecules in SOM and is slowing down their respective photochemical reactions. |
BibTeX:
@article
{Hinks2016,
title = {Effect of viscosity on photodegradation rates in complex secondary organic aerosol materials}
,author = {Hinks, Mallory L. and Brady, Monica V. and Lignell, Hanna and Song, Mijung and Grayson, James W. and Bertram, Allan K. and Lin, Peng and Laskin, Alexander and Laskin, Julia and Nizkorodov, Sergey A.}
,journal = {Physical Chemistry Chemical Physics}
,publisher = {The Royal Society of Chemistry}
,year = {2016}
,volume = {18}
,number = {13}
,pages = {8785--8793}
,url = {https://pubs.rsc.org/en/content/articlelanding/2016/cp/c5cp05226b}
,doi = {10.1039/C5CP05226B}
}
|
Generating long sequences of high-intensity femtosecond pulses,
Bitter M and Milner V,
Applied Optics
55
(4)
, 830-833
(2016),
Optical Society of America.
|
| Abstract: We present an approach to creating pulse sequences extending beyond 150&x00A0;ps in duration, comprised of 100&x00A0;&x03BC;J femtosecond pulses. A quarter of the pulse train is produced by a high-resolution pulse shaper, which allows full controllability over the timing of each pulse. Two nested Michelson interferometers follow to quadruple the pulse number and the sequence duration. To boost the pulse energy, the long train is sent through a multipass Ti:sapphire amplifier, followed by an external compressor. A periodic sequence of 84 pulses of 120&x00A0;fs width and an average pulse energy of 107&x00A0;&x03BC;J, separated by 2&x00A0;ps, is demonstrated as a proof of principle. |
BibTeX:
@article
{Bitter2016a,
title = {Generating long sequences of high-intensity femtosecond pulses}
,author = {Bitter, Martin and Milner, Valery}
,journal = {Applied Optics}
,publisher = {Optical Society of America}
,year = {2016}
,volume = {55}
,number = {4}
,pages = {830--833}
,url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-55-4-830}
,doi = {10.1364/AO.55.000830}
}
|
Controlled Intramolecular Charge Transfer Using a Sulfur-Containing Acceptor Group,
Pahlavanlu P, Christensen PR, Therrien JA and Wolf MO,
The Journal of Physical Chemistry C
120
(1)
, 70-77
(2016),
American Chemical Society.
|
| Abstract: A series of donor–acceptor (D–A) and donor–acceptor–donor (D–A–D) molecules containing anthracene chromophores paired with a sulfur-containing acceptor group have been prepared. The oxidation state of the acceptor sulfur atom controls the degree of charge transfer character in the excited state wave function. Steady-state photoluminescence spectroscopy shows more pronounced solvatochromism with increasing sulfur oxidation state. Computational methods (DFT/TD-DFT) are used to show that orbital mixing between donor and acceptor is facilitated as the oxidation state of the acceptor sulfur is increased. |
BibTeX:
@article
{Pahlavanlu2016,
title = {Controlled Intramolecular Charge Transfer Using a Sulfur-Containing Acceptor Group}
,author = {Pahlavanlu, Paniz and Christensen, Peter R. and Therrien, Jeffrey A. and Wolf, Michael O.}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2016}
,volume = {120}
,number = {1}
,pages = {70--77}
,url = {https://doi.org/10.1021/acs.jpcc.5b09826}
,doi = {10.1021/acs.jpcc.5b09826}
}
|
Rotational excitation of molecules with long sequences of intense femtosecond pulses,
Bitter M and Milner V,
Physical Review A
93
(1)
, 013420
(2016),
American Physical Society.
|
| Abstract: We investigate the prospects of creating broad rotational wave packets by means of molecular interaction with long sequences of intense femtosecond pulses. Using state-resolved rotational Raman spectroscopy of oxygen, subject to a sequence of more than 20 laser pulses with peak intensities exceeding 1013W/cm2 per pulse, we show that the centrifugal distortion is the main obstacle on the way to reaching high rotational states. We demonstrate that the timing of the pulses can be optimized to partially mitigate the centrifugal limit. The cumulative effect of a long pulse sequence results in a high degree of rotational coherence, which is shown to cause an efficient spectral broadening of probe light via cascaded Raman transitions. |
BibTeX:
@article
{Bitter2016,
title = {Rotational excitation of molecules with long sequences of intense femtosecond pulses}
,author = {Bitter, Martin and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2016}
,volume = {93}
,number = {1}
,pages = {013420}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.93.013420}
,doi = {10.1103/PhysRevA.93.013420}
}
|
Poly(p-phenylenediethynylene phosphane): A Phosphorus-Containing Macromolecule that Displays Blue Fluorescence Upon Oxidation,
Rawe BW and Gates DP,
Angewandte Chemie
127
(39)
, 11600-11604
(2015),
|
| Abstract: Despite the challenges associated with their synthesis, hybrid inorganic–organic polymers featuring heavier main-group elements spaced by p-conjugated organic functionalities have garnered considerable recent attention due to their chemical functionality and novel photophysical properties. We have succeeded in the preparation of an unprecedented organophosphorus polymer possessing functional phosphane-di-yne moieties in the main chain. Namely, poly(p-phenylenediethynylene phosphane) (PPYP) is prepared using a nickel(II)-catalyzed P?C bond-forming reaction. The hexyl-substituted PPYPs are solution processible and have been thoroughly characterized (molecular weight, Mw, ca. 104 Da vs. polystyrene; degree of polymerization, DP, ca. 10). Remarkably, although PPYP shows very weak emission upon irradiation with UV light, its oxide shows blue “turn-on” fluorescence. The present discovery bridges the areas of main-group and polymer science and opens the door to a new class of s-p-conjugated macromolecules with unique chemical functionality. |
BibTeX:
@article
{Rawe2015,
title = {Poly(p-phenylenediethynylene phosphane): A Phosphorus-Containing Macromolecule that Displays Blue Fluorescence Upon Oxidation}
,author = {Rawe, Benjamin W. and Gates, Derek P.}
,journal = {Angewandte Chemie}
,year = {2015}
,volume = {127}
,number = {39}
,pages = {11600--11604}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/ange.201504464}
,doi = {10.1002/ange.201504464}
}
|
Water diffusion in atmospherically relevant a-pinene secondary organic material,
Price HC, Mattsson J, Zhang Y, Bertram AK, Davies JF, Grayson JW, Martin ST, O’Sullivan D, Reid JP, Rickards AMJ and Murray BJ,
Chemical Science
6
(8)
, 4876-4883
(2015),
Royal Society of Chemistry.
|
| Abstract: Secondary organic material (SOM) constitutes a large mass fraction of atmospheric aerosol particles. Understanding its impact on climate and air quality relies on accurate models of interactions with water vapour. Recent research shows that SOM can be highly viscous and can even behave mechanically like a solid, leading to suggestions that particles exist out of equilibrium with water vapour in the atmosphere. In order to quantify any kinetic limitation we need to know water diffusion coefficients for SOM, but this quantity has, until now, only been estimated and has not yet been measured. We have directly measured water diffusion coefficients in the water soluble fraction of α-pinene SOM between 240 and 280 K. Here we show that, although this material can behave mechanically like a solid, at 280 K water diffusion is not kinetically limited on timescales of 1 s for atmospheric-sized particles. However, diffusion slows as temperature decreases. We use our measured data to constrain a Vignes-type parameterisation, which we extend to lower temperatures to show that SOM can take hours to equilibrate with water vapour under very cold conditions. Our modelling for 100 nm particles predicts that under mid- to upper-tropospheric conditions radial inhomogeneities in water content produce a low viscosity surface region and more solid interior, with implications for heterogeneous chemistry and ice nucleation. |
BibTeX:
@article
{C. Price2015,
title = {Water diffusion in atmospherically relevant a-pinene secondary organic material}
,author = {Price, Hannah C. and Mattsson, Johan and Zhang, Yue and Bertram, Allan K. and Davies, James F. and Grayson, James W. and Martin, Scot T. and O'Sullivan, Daniel and Reid, Jonathan P. and Rickards, Andrew M. J. and Murray, Benjamin J.}
,journal = {Chemical Science}
,publisher = {Royal Society of Chemistry}
,year = {2015}
,volume = {6}
,number = {8}
,pages = {4876--4883}
,url = {https://pubs.rsc.org/en/content/articlelanding/2015/sc/c5sc00685f}
,doi = {10.1039/C5SC00685F}
}
|
Superhydrophobic laser-ablated stainless steel substrates exhibiting Cassie–Baxter stable state,
Moradi S, Kamal S and Hatzikiriakos SG,
Surface Innovations
3
(3)
, 151-163
(2015),
|
| Abstract: In order to produce long-lasting, non-wettable surfaces, femtosecond laser ablation process was used to produce micro/nano structures on metallic surfaces. The effects of femtosecond laser irradiation process parameters (fluence, scanning speed and laser beam overlap) on the hydrophobicity of the resulting micro/nano-patterned morphologies on stainless steel were studied in detail. Seven distinctly different micro/nano patterns, namely nano-rippled, paraboloidal, sinusoidal, triple roughness, cauliflowered, tulip and scaly patterns, were fabricated. The latter pattern (scaly) was found to be identical to that of the butterfly wing structure. All patterns were classified according to laser intensity and scanning speed. Consequently, the fabricated substrates were chemically treated by silanization (Young contact angle (CA) of about 105°) in order to examine the additional effects of nanopatterning on wettability. The analysis of wettability revealed enhanced superhydrophobicity for most of these structures, particularly for the cauliflowered and scaly patterns with CAs in excess of 160° and contact angle hysteresis of less than 10°. Finally, the cauliflowered pattern was found to possess a stable composite state, which is important for certain applications such as friction (Cassie–Baxter). |
BibTeX:
@article
{Moradi2015,
title = {Superhydrophobic laser-ablated stainless steel substrates exhibiting Cassie–Baxter stable state}
,author = {Moradi, Sona and Kamal, Saeid and Hatzikiriakos, Savvas G.}
,journal = {Surface Innovations}
,year = {2015}
,volume = {3}
,number = {3}
,pages = {151-163}
,url = {https://doi.org/10.1680/jsuin.15.00001}
,doi = {10.1680/jsuin.15.00001}
}
|
Energy Transfer Pathways in a Quantum Dot-Based Concentric FRET Configuration,
Wu M, Massey M, Petryayeva E and Algar WR,
The Journal of Physical Chemistry C
119
(46)
, 26183-26195
(2015),
American Chemical Society.
|
| Abstract: The unique optical properties of semiconductor quantum dots (QDs) are highly advantageous for biological imaging and analysis, particularly when combined with Förster resonance energy transfer (FRET). A recent innovation in this area has been concentric FRET (cFRET), wherein QDs are assembled with multiple copies of two different types of fluorescent label. Although multifunctional biological probes have been developed utilizing cFRET, a detailed photophysical analysis of cFRET has not been undertaken, and energy transfer in these probes has been understood only qualitatively. Here, we characterize a prototypical QD-(A555)M-(A647)N cFRET configuration through photoluminescence (PL) intensity, decay, and photobleaching measurements. This cFRET configuration combines a central, green-emitting QD with Alexa Fluor 555 (A555) and Alexa Fluor 647 (A647) dyes that are assembled to QDs through peptide linkers, where M and N are the numbers of A555 and A647 per QD. Following initial photoexcitation of the QD, the energy transfer pathways are QD-to-A555 and QD-to-A647, which compete with one another, and A555-to-A647, which occurs subsequent to QD-to-A555 energy transfer. A rate analysis, calibrated to the conventional QD-(A555)M and QD-(A647)N FRET systems, accurately predicts quenching efficiencies and permits a first approximation of dye/QD PL intensity ratios in the cFRET configurations. CdSe/CdS/ZnS QDs and CdSeS/ZnS QDs of different sizes but similar emission characteristics are used for these experiments, and they demonstrate the general applicability of the analysis. The interplay between the three FRET pathways and nonideal behavior within this system is discussed with directions for future research. Overall, this study provides a framework and predictive power for the rational design and optimization of novel cFRET probes and biosensors for biological applications. |
BibTeX:
@article
{Wu2015,
title = {Energy Transfer Pathways in a Quantum Dot-Based Concentric FRET Configuration}
,author = {Wu, Miao and Massey, Melissa and Petryayeva, Eleonora and Algar, W. Russ}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2015}
,volume = {119}
,number = {46}
,pages = {26183--26195}
,url = {https://doi.org/10.1021/acs.jpcc.5b08612}
,doi = {10.1021/acs.jpcc.5b08612}
}
|
Emissive Ir(III) complexes bearing thienylamido groups on a 1,10-phenanthroline scaffold,
Howarth AJ, Majewski MB, Brown CM, Lelj F, Wolf MO and Patrick BO,
Dalton Transactions
44
(37)
, 16272-16279
(2015),
The Royal Society of Chemistry.
|
| Abstract: The synthesis, structures and photophysical properties of a series of bis-cyclometallated Ir(III) complexes bearing phenylpyrazole (ppz) cyclometallating ligands and phenanthroline-based ancillary ligands containing thienyl- and bithienylamido groups are reported. All complexes are emissive in solution, while in PMMA films strong emission is observed from the thienylamido substituted complex with no emission from the bithienylamido complex. The bithienylamido substituted complex has an excited state lifetime which is significantly longer than the emission lifetime, attributed to the population of non-equilibrated 3MLCT and 3LC states in this complex. This represents a rare example of this unusual excited state behaviour. DFT calculations show that the emitting 3MLCT state and the dark 3LC state on bithiophene are close in energy and that a large change in the triplet state geometry occurs upon excitation that effectively lowers the energy of the 3MLCT state below that of the dark 3LC state. The low quantum yield of the bithienylamido complex is attributed to a structural rearrangement upon relaxation back to the ground state, opening a non-radiative decay pathway. |
BibTeX:
@article
{Howarth2015,
title = {Emissive Ir(III) complexes bearing thienylamido groups on a 1,10-phenanthroline scaffold}
,author = {Howarth, Ashlee J. and Majewski, Marek B. and Brown, Christopher M. and Lelj, Francesco and Wolf, Michael O. and Patrick, Brian O.}
,journal = {Dalton Transactions}
,publisher = {The Royal Society of Chemistry}
,year = {2015}
,volume = {44}
,number = {37}
,pages = {16272--16279}
,url = {https://pubs.rsc.org/en/content/articlelanding/2015/dt/c5dt02691a}
,doi = {10.1039/C5DT02691A}
}
|
Superhydrophobic laser ablated PTFE substrates,
Falah Toosi S, Moradi S, Kamal S and Hatzikiriakos SG,
Applied Surface Science
349
, 715-723
(2015),
|
| Abstract: The effect of femtosecond laser irradiation process parameters (fluence, scanning speed and beam overlap) on the wettability of the resulted micro/nano-patterned morphologies on polytetrafluoroethylene is studied in detail. Several distinctly different micro/nano-patterns were fabricated including uniaxial and biaxial patterns. In particular, using biaxial scanning well defined pillared morphology was fabricated. The wettability analysis of the biaxially scanned samples revealed enhanced superhydrophobicity exhibiting high contact angles and low contact angle hysteresis. |
BibTeX:
@article
{FalahToosi2015,
title = {Superhydrophobic laser ablated PTFE substrates}
,author = {Falah Toosi, Salma and Moradi, Sona and Kamal, Saeid and Hatzikiriakos, Savvas G.}
,journal = {Applied Surface Science}
,year = {2015}
,volume = {349}
,pages = {715--723}
,url = {http://www.sciencedirect.com/science/article/pii/S0169433215011241}
,doi = {10.1016/j.apsusc.2015.05.026}
}
|
Validation of the poke-flow technique combined with simulations of fluid flow for determining viscosities in samples with small volumes and high viscosities,
Grayson JW, Song M, Sellier M and Bertram AK,
Atmospheric Measurement Techniques
8
(6)
, 2463-2472
(2015),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater Viscosity in particles consisting of secondary organic material (SOM) has recently become an area of research focus, since information on viscosity is needed to predict the environmental impacts of SOM particles. Recently Renbaum-Wolff et al. (2013a) developed a poke-flow technique that was combined with simulations of fluid flow to constrain the viscosities of SOM samples of 1–5 mg mass, roughly the maximum that may be collected from environmental chambers or flow tubes on a reasonable timescale. The current manuscript expands on the initial validation experiments carried out by Renbaum-Wolff et al. First, the poke-flow technique combined with simulations of fluid flow was used to determine the viscosity of sucrose–water particles over a relatively wide range of relative humidities (RHs). The lower and upper limits of viscosity at 59% RH were 1.0 × 10^1 and 1.6 × 10^4 Pa s, whilst at 37% RH the corresponding values were 7.2 × 10^4 and 4.7 × 10^6 Pa s, respectively. The results are in good agreement with recent measurements by Quintas et al. (2006) and Power et al. (2013). Second, the approach was used to determine the viscosity of two polybutene standards. The simulated lower and upper limits of viscosity for standard 1 was 2.0 × 10^2 and 1.2 × 10^4 Pa s, whilst for standard 2 the corresponding values were 3.1 × 10^2 and 2.4 × 10^4 Pa s. These values are in good agreement with values reported by the manufacturer. The results for both the sucrose–water particles and the polybutene standards show that the poke-flow technique combined with simulations of fluid flow is capable of providing both lower and upper limits of viscosity that are consistent with literature or measured values when the viscosity of the particles are in the range of ˜ 5 × 10^2 to ˜ 3 × 10^6 Pa s.textless/ptextgreater |
BibTeX:
@article
{Grayson2015,
title = {Validation of the poke-flow technique combined with simulations of fluid flow for determining viscosities in samples with small volumes and high viscosities}
,author = {Grayson, James W. and Song, Mijung and Sellier, M. and Bertram, Allan K.}
,journal = {Atmospheric Measurement Techniques}
,publisher = {Copernicus GmbH}
,year = {2015}
,volume = {8}
,number = {6}
,pages = {2463--2472}
,url = {https://www.atmos-meas-tech.net/8/2463/2015/}
,doi = {10.5194/amt-8-2463-2015}
}
|
Relative humidity-dependent viscosities of isoprene-derived secondary organic material and atmospheric implications for isoprene-dominant forests,
Song M, Liu PF, Hanna SJ, Li YJ, Martin ST and Bertram AK,
Atmospheric Chemistry and Physics
15
(9)
, 5145-5159
(2015),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater Oxidation of isoprene is an important source of secondary organic material (SOM) in atmospheric particles, especially in areas such as the Amazon Basin. Information on the viscosities, diffusion rates, and mixing times within isoprene-derived SOM is needed for accurate predictions of air quality, visibility, and climate. Currently, however, this information is not available. Using a bead-mobility technique and a poke-flow technique combined with fluid simulations, the relative humidity (RH)-dependent viscosities of SOM produced from isoprene photo-oxidation were quantified for 20–60 µm particles at 295 ± 1 K. From 84.5 to 0% RH, the viscosities for isoprene-derived SOM varied from textasciitilde 2 × 10^-1 to textasciitilde 3 × 10^5 Pa s, implying that isoprene-derived SOM ranges from a liquid to a semisolid over this RH range. These viscosities correspond to diffusion coefficients of textasciitilde 2 × 10^-8 to textasciitilde 2 × 10^-14 cm^2 s^-1 for large organic molecules that follow the Stokes–Einstein relation. Based on the diffusion coefficients, the mixing time of large organic molecules within 200 nm isoprene-derived SOM particles ranges from approximately 0.1 h to less than 1 s. To illustrate the atmospheric implications of this study’s results, the Amazon Basin is used as a case study for an isoprene-dominant forest. Considering the RH and temperature range observed in the Amazon Basin and with some assumptions about the dominant chemical compositions of SOM particles in the region, it is likely that SOM particles in this area are liquid and reach equilibrium with large gas-phase organic molecules on short time scales, less than or equal to approximately 0.1 h.textless/ptextgreater |
BibTeX:
@article
{Song2015,
title = {Relative humidity-dependent viscosities of isoprene-derived secondary organic material and atmospheric implications for isoprene-dominant forests}
,author = {Song, Mijung and Liu, P. F. and Hanna, Sarah J. and Li, Y. J. and Martin, Scot T. and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2015}
,volume = {15}
,number = {9}
,pages = {5145--5159}
,url = {https://www.atmos-chem-phys.net/15/5145/2015/}
,doi = {10.5194/acp-15-5145-2015}
}
|
Time-Gated DNA Photonic Wires with Förster Resonance Energy Transfer Cascades Initiated by a Luminescent Terbium Donor,
Massey M, Ancona MG, Medintz IL and Algar WR,
ACS Photonics
2
(5)
, 639-652
(2015),
American Chemical Society.
|
| Abstract: Functional DNA nanotechnology is a rapidly growing area of research with many prospective photonic applications, including roles as wires and switches, logic operators, and smart biological probes and delivery vectors. Photonic wire constructs are one such example and comprise a Förster resonance energy transfer (FRET) cascade between fluorescent dyes arranged periodically along a DNA scaffold. To date, the majority of research on photonic wires has focused on setting new benchmarks for efficient energy transfer over more steps and across longer distances, using almost exclusively organic fluorescent dyes and strictly DNA structures. Here, we expand the range of materials utilized with DNA photonic wires by demonstrating the use of a luminescent terbium complex (Tb) as an initial donor for a four-step FRET cascade along a 15 nm long DNA/locked nucleic acid (LNA) photonic wire. The inclusion of LNA nucleotides increases the thermal stability of the photonic wires while the Tb affords time-gated emission measurements and other optical benefits. Time-gating minimizes unwanted background emission, whether from direct excitation of fluorescent dyes along the length of the photonic wire, from excess dye-labeled DNA strands in the sample, or from a biological sample matrix. Observed efficiencies for Tb-to-dye energy transfer are also closer to the predicted values than those for dye-to-dye energy transfer, and the Tb can be used as an initial FRET donor for a variety of next-in-line acceptors at different spectral positions. We show that the key to using the Tb as an effective initial donor is to optimally position the next-in-line acceptor dye in a so-called “sweet spot” where the FRET efficiency is sufficiently high for practicality, but not so high as to suppress time-gated emission by shortening the Tb emission lifetime to within the instrument lag or delay time necessary for measurements. Overall, the initiation of a time-gated FRET cascade with a Tb donor is a very promising strategy for the design, characterization, and application of DNA-based photonic wires and other functional DNA nanostructures. |
BibTeX:
@article
{Massey2015,
title = {Time-Gated DNA Photonic Wires with Förster Resonance Energy Transfer Cascades Initiated by a Luminescent Terbium Donor}
,author = {Massey, Melissa and Ancona, Mario G. and Medintz, Igor L. and Algar, W. Russ}
,journal = {ACS Photonics}
,publisher = {American Chemical Society}
,year = {2015}
,volume = {2}
,number = {5}
,pages = {639--652}
,url = {https://doi.org/10.1021/acsphotonics.5b00052}
,doi = {10.1021/acsphotonics.5b00052}
}
|
Two Colors of Light Are Needed to Break Bonds and Release Small Molecules from the Surface of SiO2–Au Core–Shell Nanoparticles,
Asadirad AM and Branda NR,
Journal of the American Chemical Society
137
(8)
, 2824-2827
(2015),
American Chemical Society.
|
| Abstract: The photothermal effect is not able to break bonds and release small molecules from the surface of SiO2–Au core–shell nanoparticles unless the nanosystem is first exposed to visible light. Only after this light triggers the ring-opening reaction of dithienylethene chromophores attached to the surface of the nanoparticles can the heat generated by the NIR light induce reverse Diels–Alder reactions. |
BibTeX:
@article
{Asadirad2015,
title = {Two Colors of Light Are Needed to Break Bonds and Release Small Molecules from the Surface of SiO2–Au Core–Shell Nanoparticles}
,author = {Asadirad, Amir M. and Branda, Neil R.}
,journal = {Journal of the American Chemical Society}
,publisher = {American Chemical Society}
,year = {2015}
,volume = {137}
,number = {8}
,pages = {2824--2827}
,url = {https://doi.org/10.1021/ja513210s}
,doi = {10.1021/ja513210s}
}
|
Self-assembly of nanoparticles onto the surfaces of polystyrene spheres with a tunable composition and loading,
Pilapil BK, Wang MCP, Paul MTY, Nazemi A and Gates BD,
Nanotechnology
26
(5)
, 055601
(2015),
IOP Publishing.
|
| Abstract: Functional colloidal materials were prepared by design through the self-assembly of nanoparticles (NPs) on the surfaces of polystyrene (PS) spheres with control over NP surface coverage, NP-to-NP spacing, and NP composition. The ability to control and fine tune the coating was extended to the first demonstration of the co-assembly of NPs of dissimilar composition onto the same PS sphere, forming a multi-component coating. A broad range of NP decorated PS (PS@NPs) spheres were prepared with uniform coatings attributed to electrostatic and hydrogen bonding interactions between stabilizing groups on the NPs and the functionalized surfaces of the PS spheres. This versatile two-step method provides more fine control than methods previously demonstrated in the literature. These decorated PS spheres are of interest for a number of applications, such as catalytic reactions where the PS spheres provide a support for the dispersion, stabilization, and recovery of NP catalysts. The catalytic properties of these PS@NPs spheres were assessed by studying the catalytic degradation of azo dyes, an environmental contaminant detrimental to eye health. The PS@NPs spheres were used in multiple, sequential catalytic reactions while largely retaining the NP coating. |
BibTeX:
@article
{Pilapil2015,
title = {Self-assembly of nanoparticles onto the surfaces of polystyrene spheres with a tunable composition and loading}
,author = {Pilapil, Brandy K. and Wang, Michael C. P. and Paul, Michael T. Y. and Nazemi, Amir and Gates, Byron D.}
,journal = {Nanotechnology}
,publisher = {IOP Publishing}
,year = {2015}
,volume = {26}
,number = {5}
,pages = {055601}
,url = {https://doi.org/10.1088%2F0957-4484%2F26%2F5%2F055601}
,doi = {10.1088/0957-4484/26/5/055601}
}
|
Elucidating the Origin of Enhanced Phosphorescence Emission in the Solid State (EPESS) in Cyclometallated Iridium Complexes,
Howarth AJ, Patia R, Davies DL, Lelj F, Wolf MO and Singh K,
European Journal of Inorganic Chemistry
2014
(23)
, 3657-3664
(2014),
|
| Abstract: Abstract A new mechanism for enhanced phosphorescence emission in the solid state (EPESS) in cyclometallated Ir complexes with the general formula [Ir(CN)2(NO)] involving distortion of the six-membered chelate ring of the ancillary ligand is proposed. Photophysical and computational studies show that neither π-stacking nor restricted rotation cause the observed EPESS in these complexes and that ligand distortions in the triplet excited state are responsible for EPESS |
BibTeX:
@article
{Howarth2014,
title = {Elucidating the Origin of Enhanced Phosphorescence Emission in the Solid State (EPESS) in Cyclometallated Iridium Complexes}
,author = {Howarth, Ashlee J. and Patia, Raissa and Davies, David L. and Lelj, Francesco and Wolf, Michael O. and Singh, Kuldip}
,journal = {European Journal of Inorganic Chemistry}
,year = {2014}
,volume = {2014}
,number = {23}
,pages = {3657-3664}
,url = {https://chemistry-europe.onlinelibrary.wiley.com/doi/abs/10.1002/ejic.201402495}
,doi = {10.1002/ejic.201402495}
}
|
Tuning the Emission Lifetime in Bis-cyclometalated Iridium(III) Complexes Bearing Iminopyrene Ligands,
Howarth AJ, Davies DL, Lelj F, Wolf MO and Patrick BO,
Inorganic Chemistry
53
(22)
, 11882-11889
(2014),
American Chemical Society.
|
| Abstract: Bis-cyclometalated Ir(III) complexes with the general formula Ir(ppz)2(XtextasciicircumNPyrene), where ppz = 1-phenylpyrazole and XtextasciicircumNPyrene is a bidentate chelate with X = N or O, are reported. Modifications on the ancillary ligand containing pyrene drastically affect the emission lifetimes observed (0.329 to 104 µs). Extended emission lifetimes in these complexes compared to model complexes result from reversible electronic energy transfer or the observation of dual emission containing along-lived pyrene ligand-centered triplet (3LC) component. A combination of steady-state and time-resolved spectroscopic techniques are used to observe reversible electronic energy transfer in solution between the iridium core and pyrene moiety in the complex [Ir(ppz)2(NMetextasciicircumNCH2Pyr)][PF6] (2), where NMetextasciicircumNCH2Pyr = N-(pyren-1-ylmethyl)-1-(pyridin-2-yl)ethaneimine. Studies on [Ir(ppz)2(NMetextasciicircumNCH2Pyr)][PF6] in a poly(methyl methacrylate) (PMMA) film reveal that reversible energy transfer is no longer effective, and instead, dual emission with a long-lived 3LC component from pyrene is observed. Dual emission is observed in additional cyclometalated iridium complexes bearing pyrene-containing ancillary ligands NtextasciicircumNPyrene and OtextasciicircumNPyrene when the complexes are dispersed in a PMMA film. |
BibTeX:
@article
{Howarth2014a,
title = {Tuning the Emission Lifetime in Bis-cyclometalated Iridium(III) Complexes Bearing Iminopyrene Ligands}
,author = {Howarth, Ashlee J. and Davies, David L. and Lelj, Francesco and Wolf, Michael O. and Patrick, Brian O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2014}
,volume = {53}
,number = {22}
,pages = {11882--11889}
,url = {https://doi.org/10.1021/ic501032t}
,doi = {10.1021/ic501032t}
}
|
Paper Parameter Estimation Using Terahertz Time-Domain Spectroscopy,
Dodge JS, Mousavi P, Bushfield I, Savard S, Jez D and Haran F,
, In 2014 International Symposium on Optomechatronic Technologies.
, 119-120
(2014),
|
| Abstract: We demonstrate a terahertz time-domain technique for measuring thickness, moisture and basis weight of paper. We validate our technique for a sample compressed to different thicknesses and establish uncertainty limits using Monte Carlo simulations. |
BibTeX:
@inproceedings
{Dodge2014,
title = {Paper Parameter Estimation Using Terahertz Time-Domain Spectroscopy}
,author = {Dodge, J. Steven and Mousavi, Payam and Bushfield, Ian and Savard, Stéphane and Jez, David and Haran, Frank}
,booktitle = {2014 International Symposium on Optomechatronic Technologies}
,year = {2014}
,pages = {119--120}
,doi = {10.1109/ISOT.2014.36}
}
|
Enhancement of Quantum Dot Förster Resonance Energy Transfer within Paper Matrices and Application to Proteolytic Assays,
Kim H, Petryayeva E and Algar WR,
IEEE Journal of Selected Topics in Quantum Electronics
20
(3)
, 141-151
(2014),
|
| Abstract: Brightly luminescent semiconductor quantum dots (QDs) continue to play an increasing role in biophotonic research and applications such as bioassays. Here, we present methods for the immobilization of QDs on the cellulose fibers of paper substrates for Förster resonance energy transfer (FRET)-based assays of proteolytic activity. Steady-state and time-resolved fluorescence characterization of FRET between immobilized QDs and self-assembled dye-labeled peptides within the paper matrix revealed a substantial enhancement in energy transfer efficiency. Compared to bulk solution, the rate of energy transfer increased approximately fourfold resulting in a concomitant sevenfold increase in the ratio of FRET-sensitized acceptor dye emission and quenched QD emission. Spots of immobilized QDs with different amounts of dye-labeled peptide had bright luminescence under UV/violet illumination and the net QD and Alexa Fluor 555 (A555) dye emission was visible by eye as different colors. Tryptic digestion of the peptides linking the QD donor and the acceptor dyes resulted in loss of FRET. Changes in the dye/QD photoluminescence (PL) ratio permitted the tracking of proteolytic activity, including the effect of increasing amounts of aprotinin, a potent inhibitor of trypsin. The combination of QDs, a paper substrate, and enhanced FRET has strong potential for developing bioassays. |
BibTeX:
@article
{Kim2014,
title = {Enhancement of Quantum Dot Förster Resonance Energy Transfer within Paper Matrices and Application to Proteolytic Assays}
,author = {Kim, Hyungki and Petryayeva, Eleonora and Algar, W. Russ}
,journal = {IEEE Journal of Selected Topics in Quantum Electronics}
,year = {2014}
,volume = {20}
,number = {3}
,pages = {141--151}
,doi = {10.1109/JSTQE.2013.2280498}
}
|
| Moradi S, Englezos P and Hatzikiriakos SG (2014), “Contact Angle Hysteresis of Non-Flattened-Top Micro/Nanostructures”. March, 2014. |
| Abstract: A two-dimensional (2D) thermodynamic model is proposed to predict the contact angle (CA) and contact angle hysteresis (CAH) of different types of surface geometries, particularly those with asperities having nonflattened tops. The model is evaluated by micro/nano sinusoidal and parabolic patterns fabricated by laser ablation. These microstructures are analyzed thermodynamically through the use of the Gibbs free energy to obtain the equilibrium contact angle (CA) and contact angle hysteresis (CAH). The effects of the geometrical details of two types of microstructures on maximizing the superhydrophobicity of the nanopatterned surface are also discussed in an attempt to design surfaces with desired and/or optimum wetting characteristics. The analysis of the various surfaces reveals the important geometrical parameters that may lead to the lotus effect (high CA textgreater 150° and low CAH textless 10°) or petal effect (high CA textgreater 150° and high CAH » 10°). |
BibTeX:
@misc{Moradi2014,
author = {Moradi, Sona and Englezos, Peter and Hatzikiriakos, Savvas G.},
title = {Contact Angle Hysteresis of Non-Flattened-Top Micro/Nanostructures},
publisher = {American Chemical Society},
year = {2014},
url = {https://pubs.acs.org/doi/pdf/10.1021/la500277n},
doi = {10.1021/la500277n}
}
|
Direct C–F Bond Formation Using Photoredox Catalysis,
Rueda-Becerril M, Mahé O, Drouin M, Majewski MB, West JG, Wolf MO, Sammis GM and Paquin J-F,
Journal of the American Chemical Society
136
(6)
, 2637-2641
(2014),
American Chemical Society.
|
| Abstract: We have developed the first example of a photoredox catalytic method for the formation of carbon–fluorine (C–F) bonds. The mechanism has been studied using transient absorption spectroscopy and involves a key single-electron transfer from the 3MLCT (triplet metal-to-ligand charge transfer) state of Ru(bpy)32+ to Selectfluor. Not only does this represent a new reaction for photoredox catalysis, but the mild reaction conditions and use of visible light also make it a practical improvement over previously developed UV-mediated decarboxylative fluorinations. |
BibTeX:
@article
{RuedaBecerril2014,
title = {Direct C–F Bond Formation Using Photoredox Catalysis}
,author = {Rueda-Becerril, Montserrat and Mahé, Olivier and Drouin, Myriam and Majewski, Marek B. and West, Julian G. and Wolf, Michael O. and Sammis, Glenn M. and Paquin, Jean-François}
,journal = {Journal of the American Chemical Society}
,publisher = {American Chemical Society}
,year = {2014}
,volume = {136}
,number = {6}
,pages = {2637--2641}
,url = {https://doi.org/10.1021/ja412083f}
,doi = {10.1021/ja412083f}
}
|
Long-lived, directional photoinduced charge separation in RuII complexes bearing laminate polypyridyl ligands.,
Majewski MB, Tacconi NRd, MacDonnell FM and Wolf MO,
Chemistry
(2013),
|
| Abstract: RuII complexes incorporating both amide-linked bithiophene donor ancillary ligands and laminate acceptor ligands; dipyrido[3,2-a:2′,3′-c]phenazine (dppz), tetrapyrido[3,2-a:2′,3′-c:3”,2”-h:2”’,3”’-j]phenazine (tpphz), and 9,11,20,22-tetraazatetrapyrido[3,2-a:2′,3′-c:3”,2”-l:2”’,3”’]-pentacene (tatpp) exhibit long-lived charge separated (CS) states, which have been analyzed using time-resolved transient absorption (TA), fluorescence, and electronic absorption spectroscopy in addition to ground state electrochemical and spectroelectrochemical measurements. These complexes possess two electronically relevant ³MLCT states related to electron occupation of MOs localized predominantly on the proximal bpy-like portion and central (or distal) phenazine-like portion of the acceptor ligand as well as energetically similar ³LC and ³ILCT states. The unusually long excited state lifetimes (t up to 7 µs) observed in these complexes reflect an equilibration of the ³MLCTprox or ³MLCTdist states with additional triplet states, including a ³LC state and a ³ILCT state that formally localizes a hole on the bithiophene moiety and an electron on the laminate acceptor ligand. Coordination of a ZnII ion to the open coordination site of the laminate acceptor ligand is observed to significantly lower the energy of the ³MLCTdist state by decreasing the magnitude of the excited state dipole and resulting in much shorter excited state lifetimes. The presence of the bithiophene donor group is reported to substantially extend the lifetime of these Zn adducts via formation of a ³ILCT state that can equilibrate with the ³MLCTdist state. In tpphz complexes, ZnII coordination can reorder the energy of the ³MLCTprox and ³MLCTdist states such that there is a distinct switch from one state to the other. The net result is a series of complexes that are capable of forming CS states with electron-hole spatial separation of up to 14 Å and possess exceptionally long lifetimes by equilibration with other triplet states. |
BibTeX:
@article
{Majewski2013,
title = {Long-lived, directional photoinduced charge separation in RuII complexes bearing laminate polypyridyl ligands.}
,author = {Majewski, Marek B. and Tacconi, Norma R. de and MacDonnell, Frederick M. and Wolf, Michael O.}
,journal = {Chemistry}
,year = {2013}
,doi = {10.1002/chem.201203786}
}
|
Optically Active Nanoparticle Coated Polystyrene Spheres,
Kinkead B, Ali AA, Boyer J-C and Gates BD,
MRS Online Proceedings Library Archive
1546
(2013),
Cambridge University Press.
|
| Abstract: Nanoparticles (NPs) with either plasmonic or upconverting properties have been selectively coated onto the surfaces of polystyrene (PS) spheres, imparting their optical properties to the PS colloids. These NP coated PS spheres have many potential applications, such as in medicine as drug-delivery systems or diagnostic tools. To prepare the NP coated PS spheres, gold or core-shell NaYF4Tm0.5Yb30/NaYF4 NPs were synthesized and separately combined with amino-functionalized PS spheres. The mechanism by which the NPs adhered to the PS spheres is attributed to interactions of the NP and a polyvinylpyrrolidone additive with the surfaces of the PS spheres. Two-photon fluorescence microscopy and SERS analysis demonstrate the potential applications of these NP coated PS spheres. |
BibTeX:
@article
{Kinkead2013,
title = {Optically Active Nanoparticle Coated Polystyrene Spheres}
,author = {Kinkead, Brandy and Ali, Abdiwali A. and Boyer, John-C. and Gates, Byron D.}
,journal = {MRS Online Proceedings Library Archive}
,publisher = {Cambridge University Press}
,year = {2013}
,volume = {1546}
,url = {https://www.cambridge.org/core/journals/mrs-online-proceedings-library-archive/article/optically-active-nanoparticle-coated-polystyrene-spheres/D078C41540A749E75EEDCA6C797A21E1}
,doi = {10.1557/opl.2013.606}
}
|
Synthesis, characterization, and biological studies of emissive rhenium–glutamine conjugates,
Huang R, Langille G, Gill RK, Li CMJ, Mikata Y, Wong MQ, Yapp DT and Storr T,
JBIC Journal of Biological Inorganic Chemistry
18
(7)
, 831-844
(2013),
|
| Abstract: Two new rhenium complexes containing pyridine–triazole (pyta) and quinoline–triazole (quinta) ligands with attached glutamine-targeting agents have been characterized and tested for uptake in the HT-29 human colon adenocarcinoma cell line. The glutamine moiety in Re(CO)3Br(pyta) (1) and Re(CO)3Br(quinta) (2) remains pendant in solution. Both complexes exhibit absorptions in the 300–400-nm range with metal-to-ligand charge transfer (MLCT) character, as predicted by time-dependent density functional theory calculations. Geometrical analysis by theoretical calculations provides information on the cationic complexes 1+ and 2+ resulting from aquo for halide ligand exchange under aqueous conditions. The emissive properties of both complexes were studied under aqueous conditions, and the measured quantum yields were 0.46 % for 1+ and 0.18 % for 2+. The large Stokes shifts and oxygen sensitivity of the emission suggest a 3MLCT process for both complexes. Cell studies in the HT-29 cell line demonstrate that both complexes are nontoxic over a large concentration range (0–1.4 mM). Preliminary uptake studies show that 2+, but not 1+, displays significant concentration-dependent uptake at 3 and 24 h. |
BibTeX:
@article
{Huang2013,
title = {Synthesis, characterization, and biological studies of emissive rhenium–glutamine conjugates}
,author = {Huang, Rachel and Langille, Graeme and Gill, Ravanjir K. and Li, Cindy Mei Jin and Mikata, Yuji and Wong, May Q. and Yapp, Donald T. and Storr, Tim}
,journal = {JBIC Journal of Biological Inorganic Chemistry}
,year = {2013}
,volume = {18}
,number = {7}
,pages = {831--844}
,url = {https://doi.org/10.1007/s00775-013-1023-3}
,doi = {10.1007/s00775-013-1023-3}
}
|
Proteolytic Assays on Quantum-Dot-Modified Paper Substrates Using Simple Optical Readout Platforms,
Petryayeva E and Algar WR,
Analytical Chemistry
85
(18)
, 8817-8825
(2013),
American Chemical Society.
|
| Abstract: Paper-based assays are a promising diagnostic format for point-of-care applications, field deployment, and other low-resource settings. To date, the majority of efforts to integrate nanomaterials with paper-based assays have utilized gold nanoparticles. Here, we show that semiconductor quantum dots (QDs), in combination with Förster resonance energy transfer (FRET), are also suitable nanomaterials for developing paper-based assays. Paper fibers were chemically modified with thiol ligands to immobilize CdSeS/ZnS QDs, the QDs were self-assembled with dye-labeled peptides to generate efficient FRET, and steady-state and fluorescence lifetime imaging microscopy (FLIM) were used for characterization. Peptides were selected as substrates for three different proteases and a series of kinetic assays for proteolytic activity was carried out, including multiplexed assays and pro-enzyme activation assays. Quantitative results were obtained within 5–60 min at levels as low as 1–2 nM of protease. These assays were possible using simple optical readout platforms that did not negate the low cost, ease of use, and overall accessibility advantages of paper-based assays. A violet light-emitting diode (LED) excitation source and color imaging with either a digital camera, consumer webcam, or smartphone camera were sufficient for analysis on the basis of a red/green color intensity ratio. At most, a universal serial bus (USB) connection to a computer was required and the instrumentation cost orders of magnitude less than that typically utilized for in vitro bioanalyses with QDs. This work demonstrates that QDs are valuable probes for developing a new generation of paper-based diagnostics. |
BibTeX:
@article
{Petryayeva2013,
title = {Proteolytic Assays on Quantum-Dot-Modified Paper Substrates Using Simple Optical Readout Platforms}
,author = {Petryayeva, Eleonora and Algar, W. Russ}
,journal = {Analytical Chemistry}
,publisher = {American Chemical Society}
,year = {2013}
,volume = {85}
,number = {18}
,pages = {8817--8825}
,url = {https://doi.org/10.1021/ac4020066}
,doi = {10.1021/ac4020066}
}
|
Femtosecond laser irradiation of metallic surfaces: effects of laser parameters on superhydrophobicity,
Moradi S, Kamal S, Englezos P and Hatzikiriakos SG,
Nanotechnology
24
(41)
, 415302
(2013),
IOP Publishing.
|
| Abstract: This work studies in detail the effect of femtosecond laser irradiation process parameters (fluence and scanning speed) on the hydrophobicity of the resulting micro/nano-patterned morphologies on stainless steel. Depending on the laser parameters, four distinctly different nano-patterns were produced, namely nano-rippled, parabolic-pillared, elongated sinusoidal-pillared and triple roughness nano-structures. All of the produced structures were classified according to a newly defined parameter, the laser intensity factor (LIF); by increasing the LIF, the ablation rate and periodicity of the asperities increase. In order to decrease the surface energy, all of the surfaces were coated with a fluoroalkylsilane agent. Analysis of the wettability revealed enhanced superhydrophobicity for most of these structures, particularly those possessing the triple roughness pattern that also exhibited low contact angle hysteresis. The high permanent superhydrophobicity of this pattern is due to the special micro/nano-structure of the surface that facilitates the Cassie–Baxter state. |
BibTeX:
@article
{Moradi2013,
title = {Femtosecond laser irradiation of metallic surfaces: effects of laser parameters on superhydrophobicity}
,author = {Moradi, Sona and Kamal, Saeid and Englezos, Peter and Hatzikiriakos, Savvas G.}
,journal = {Nanotechnology}
,publisher = {IOP Publishing}
,year = {2013}
,volume = {24}
,number = {41}
,pages = {415302}
,url = {https://doi.org/10.1088%2F0957-4484%2F24%2F41%2F415302}
,doi = {10.1088/0957-4484/24/41/415302}
}
|
Synthesis, Structure, and Magnetic Properties of Bithiophene- and Terthiophene-Linked Manganese Metal–Organic Frameworks,
Earl LD, Patrick BO and Wolf MO,
Inorganic Chemistry
52
(17)
, 10021-10030
(2013),
American Chemical Society.
|
| Abstract: A series of metal–organic frameworks (MOFs) containing manganese centers and oligothiophene dicarboxylate linkers have been synthesized: [Mn(3PhT2DC)(DMF)0.45(H2O)2.55·1.55DMF]n (1), [Mn6(3HT2DC)6(DMF)3(H2O)5·xDMF·yH2O]n (2), [Mn(T3DC)(H2O)2]n (3), [Mn(T3DC)(H2O)1.5]n (4), and [Mn(Ph2T3DC)(DMF)2]n (5) (H23PhT2DC = 3,3′-diphenyl-2,2-bithiophene-5,5′-dicarboxylic acid; H23HT2DC= 3,3′-dihexyl-2,2′-bithiophene-5,5′-dicarboxylic acid; H2T3DC = 2,2′:5′,2?-terthiophene-5,5?-dicarboxylic acid; H2Ph2T3DC = 3′,4′-diphenyl-2,2′:5′,2?-terthiophene-5,5?-dicarboxylic acid, DMF = N,N-dimethylformamide). Compound 1 exists as a 2D sheet, 2–4 are 3D frameworks, and 5 is a 1D chain. Compounds 3 and 4 are isomers, and 3–5 are the first examples of crystallographically characterized terthiophene coordination polymers. In the case of 1, 2, and 5, the extended structure is sensitive to ß substitution of the oligothiophene linkers. Compounds 1–3 and 5 show antiferromagnetic behavior with typical values of g and J, and 3 exhibits a spin canting transition at 40 K. |
BibTeX:
@article
{Earl2013,
title = {Synthesis, Structure, and Magnetic Properties of Bithiophene- and Terthiophene-Linked Manganese Metal–Organic Frameworks}
,author = {Earl, Lyndsey D. and Patrick, Brian O. and Wolf, Michael O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2013}
,volume = {52}
,number = {17}
,pages = {10021--10030}
,url = {https://doi.org/10.1021/ic401305c}
,doi = {10.1021/ic401305c}
}
|
Photophysical behaviour of cyclometalated iridium(III) complexes with phosphino(terthiophene) ligands,
Moore SA, Davies DL, Karim MM, Nagle JK, Wolf MO and Patrick BO,
Dalton Transactions
42
(34)
, 12354-12363
(2013),
The Royal Society of Chemistry.
|
| Abstract: Six new IrIII complexes containing the 3′-phosphino-2,2′:5′,2”-terthiophene (PT3) ligand in three different coordination modes are reported. The electronic properties of the complexes are characterized by cyclic voltammetry, absorption, emission and time-resolved transient absorption spectroscopies and DFT/TDDFT calculations. The electrochemical and photophysical behaviour of the complexes was found to be dominated by the PT3 ligand. For the complexes in which the PT3 ligand is coordinated in a bidentate P,S or P,C mode, the lowest energy absorption band is attributed to p–p* PT3 localized transitions consistent with observations from DFT calculations. Emission quantum yields are low in all cases (textless0.07) and emission lifetimes are short (textless50 ns). Intersystem crossing leads to a long-lived triplet state (3L) also localized on the PT3 group. In the complex where the PT3 ligand is coordinated only via the phosphine, TDDFT calculations suggest that there is some MLCT (and Cl-PT3 CT) character in the lowest energy transition. |
BibTeX:
@article
{Moore2013,
title = {Photophysical behaviour of cyclometalated iridium(III) complexes with phosphino(terthiophene) ligands}
,author = {Moore, Stephanie A. and Davies, David L. and Karim, Marcus M. and Nagle, Jeffrey K. and Wolf, Michael O. and Patrick, Brian O.}
,journal = {Dalton Transactions}
,publisher = {The Royal Society of Chemistry}
,year = {2013}
,volume = {42}
,number = {34}
,pages = {12354--12363}
,url = {https://pubs.rsc.org/en/content/articlelanding/2013/dt/c3dt51320c}
,doi = {10.1039/C3DT51320C}
}
|
Interactions of Polyelectrolytes with Water and Ions at Air/Water Interfaces Studied by Phase-Sensitive Sum Frequency Generation Vibrational Spectroscopy,
Hu D, Yang Z and Chou KC,
The Journal of Physical Chemistry C
117
(30)
, 15698-15703
(2013),
American Chemical Society.
|
| Abstract: Interactions of the polyelectrolyte partially hydrolyzed polyacrylamide (HPAM) with water and cations at air/liquid interfaces were studied using phase-sensitive sum frequency generation (SFG) vibrational spectroscopy. In contrast to the conventional SFG vibrational spectroscopy which measures only the amplitude of the second-order susceptibility textbar?(2)textbar, the heterodyne-detected SFG measures the complex ?(2) which contains information about the absolute orientation of surface molecules. While the OH groups of water near a neat air/water interface mostly pointed down to the bulk (downward), the presence of the polyelectrolyte caused flipping of water molecules with the hydrogen being oriented upward. With 10–7 M HPAM, water showed a highly ordered structure with a single peak near 3100 cm–1, but higher concentrations resulted in a less ordered water structure with multiple peaks. The addition of the monovalent cation Na+ to the polyelectrolyte solution did not affect the conformation of the polyelectrolyte, though the water molecules flipped back to a structure similar to that of a neat air/water interface with the hydrogen pointing down. On the other hand, the addition of divalent cation Ca2+ not only changed the conformation of the polyelectrolyte but also completely destroyed the ordered structure of interfacial water molecules. The observed phenomena support the polymer–ion complex model in which a divalent cation can interact with two intrachain or interchain charges and form a jointing point. The amorphous nature of the polymer–ion complex explained the disappearance of the ordered water structure in the presence of divalent cations. |
BibTeX:
@article
{Hu2013,
title = {Interactions of Polyelectrolytes with Water and Ions at Air/Water Interfaces Studied by Phase-Sensitive Sum Frequency Generation Vibrational Spectroscopy}
,author = {Hu, Dan and Yang, Zheng and Chou, Keng C.}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2013}
,volume = {117}
,number = {30}
,pages = {15698--15703}
,url = {https://doi.org/10.1021/jp404308g}
,doi = {10.1021/jp404308g}
}
|
A “Plug-and-Play” Method to Prepare Water-Soluble Photoresponsive Encapsulated Upconverting Nanoparticles Containing Hydrophobic Molecular Switches,
Wu T, Boyer J-C, Barker M, Wilson D and Branda NR,
Chemistry of Materials
25
(12)
, 2495-2502
(2013),
American Chemical Society.
|
| Abstract: A convenient and versatile protocol to encapsulate lanthanide doped upconverting nanoparticles by an amphiphilic polymer shell containing photoresponsive diarylethene chromophores was developed. The assemblies are all water-soluble and fluoresce in the visible region of the spectrum when excited with 980 nm near-infrared light. The fluorescent emission can be selectively and reversibly modulated by alternatively irradiating the photoresponsive nanoparticles with UV light and visible light, which triggers ring-closing and ring-opening reactions of the chromophores, respectively. Fluorescence lifetime experiments suggest that the quenching mechanism is a combination of energy transfer and emission-reabsorption processes. These photoresponsive upconverting nanoparticles have the potential to advance bioimaging and other applications in nanophotonics. |
BibTeX:
@article
{Wu2013,
title = {A “Plug-and-Play” Method to Prepare Water-Soluble Photoresponsive Encapsulated Upconverting Nanoparticles Containing Hydrophobic Molecular Switches}
,author = {Wu, Tuoqi and Boyer, John-Christopher and Barker, Madeleine and Wilson, Danielle and Branda, Neil R.}
,journal = {Chemistry of Materials}
,publisher = {American Chemical Society}
,year = {2013}
,volume = {25}
,number = {12}
,pages = {2495--2502}
,url = {https://doi.org/10.1021/cm400802d}
,doi = {10.1021/cm400802d}
}
|
Gas–particle partitioning of atmospheric aerosols: interplay of physical state, non-ideal mixing and morphology,
Shiraiwa M, Zuend A, Bertram AK and Seinfeld JH,
Physical Chemistry Chemical Physics
15
(27)
, 11441-11453
(2013),
The Royal Society of Chemistry.
|
| Abstract: Atmospheric aerosols, comprising organic compounds and inorganic salts, play a key role in air quality and climate. Mounting evidence exists that these particles frequently exhibit phase separation into predominantly organic and aqueous electrolyte-rich phases. As well, the presence of amorphous semi-solid or glassy particle phases has been established. Using the canonical system of ammonium sulfate mixed with organics from the ozone oxidation of a-pinene, we illustrate theoretically the interplay of physical state, non-ideality, and particle morphology affecting aerosol mass concentration and the characteristic timescale of gas–particle mass transfer. Phase separation can significantly affect overall particle mass and chemical composition. Semi-solid or glassy phases can kinetically inhibit the partitioning of semivolatile components and hygroscopic growth, in contrast to the traditional assumption that organic compounds exist in quasi-instantaneous gas–particle equilibrium. These effects have significant implications for the interpretation of laboratory data and the development of improved atmospheric air quality and climate models. |
BibTeX:
@article
{Shiraiwa2013,
title = {Gas–particle partitioning of atmospheric aerosols: interplay of physical state, non-ideal mixing and morphology}
,author = {Shiraiwa, Manabu and Zuend, Andreas and Bertram, Allan K. and Seinfeld, John H.}
,journal = {Physical Chemistry Chemical Physics}
,publisher = {The Royal Society of Chemistry}
,year = {2013}
,volume = {15}
,number = {27}
,pages = {11441--11453}
,url = {https://pubs.rsc.org/en/content/articlelanding/2013/cp/c3cp51595h}
,doi = {10.1039/C3CP51595H}
}
|
Viscosity of a-pinene secondary organic material and implications for particle growth and reactivity,
Renbaum-Wolff L, Grayson JW, Bateman AP, Kuwata M, Sellier M, Murray BJ, Shilling JE, Martin ST and Bertram AK,
Proceedings of the National Academy of Sciences
110
(20)
, 8014-8019
(2013),
National Academy of Sciences.
|
| Abstract: Particles composed of secondary organic material (SOM) are abundant in the lower troposphere. The viscosity of these particles is a fundamental property that is presently poorly quantified yet required for accurate modeling of their formation, growth, evaporation, and environmental impacts. Using two unique techniques, namely a “bead-mobility” technique and a “poke-flow” technique, in conjunction with simulations of fluid flow, the viscosity of the water-soluble component of SOM produced by a-pinene ozonolysis is quantified for 20- to 50-µm particles at 293–295 K. The viscosity is comparable to that of honey at 90% relative humidity (RH), similar to that of peanut butter at 70% RH, and at least as viscous as bitumen at =30% RH, implying that the studied SOM ranges from liquid to semisolid or solid across the range of atmospheric RH. These data combined with simple calculations or previous modeling studies are used to show the following: (i) the growth of SOM by the exchange of organic molecules between gas and particle may be confined to the surface region of the particles for RH = 30 (ii) at =30% RH, the particle-mass concentrations of semivolatile and low-volatility organic compounds may be overpredicted by an order of magnitude if instantaneous equilibrium partitioning is assumed in the bulk of SOM particles; and (iii) the diffusivity of semireactive atmospheric oxidants such as ozone may decrease by two to five orders of magnitude for a drop in RH from 90% to 30%. These findings have possible consequences for predictions of air quality, visibility, and climate. |
BibTeX:
@article
{RenbaumWolff2013a,
title = {Viscosity of a-pinene secondary organic material and implications for particle growth and reactivity}
,author = {Renbaum-Wolff, Lindsay and Grayson, James W. and Bateman, Adam P. and Kuwata, Mikinori and Sellier, Mathieu and Murray, Benjamin J. and Shilling, John E. and Martin, Scot T. and Bertram, Allan K.}
,journal = {Proceedings of the National Academy of Sciences}
,publisher = {National Academy of Sciences}
,year = {2013}
,volume = {110}
,number = {20}
,pages = {8014--8019}
,url = {https://www.pnas.org/content/110/20/8014}
,doi = {10.1073/pnas.1219548110}
}
|
Photothermal release of singlet oxygen from gold nanoparticles,
Asadirad AM, Erno Z and Branda NR,
Chemical Communications
49
(50)
, 5639-5641
(2013),
The Royal Society of Chemistry.
|
| Abstract: Anthracene endoperoxide ligands anchored to the surfaces of gold nanoparticles undergo bond breaking and release singlet oxygen when the nanoparticles convert 532 nm laser light to heat localized near their surfaces. |
BibTeX:
@article
{Asadirad2013,
title = {Photothermal release of singlet oxygen from gold nanoparticles}
,author = {Asadirad, Amir Mahmoud and Erno, Zach and Branda, Neil R.}
,journal = {Chemical Communications}
,publisher = {The Royal Society of Chemistry}
,year = {2013}
,volume = {49}
,number = {50}
,pages = {5639--5641}
,url = {https://pubs.rsc.org/en/content/articlelanding/2013/cc/c3cc42217h}
,doi = {10.1039/C3CC42217H}
}
|
Investigation of Sub-100 nm Gold Nanoparticles for Laser-Induced Thermotherapy of Cancer,
Leung JP, Wu S, Chou KC and Signorell R,
Nanomaterials
3
(1)
, 86-106
(2013),
Multidisciplinary Digital Publishing Institute.
|
| Abstract: Specialized gold nanostructures are of interest for the development of alternative treatment methods in medicine. Photothermal therapy combined with gene therapy that supports hyperthermia is proposed as a novel multimodal treatment method for prostate cancer. In this work, photothermal therapy using small (<100 nm) gold nanoparticles and near-infrared (NIR) laser irradiation combined with gene therapy targeting heat shock protein (HSP) 27 was investigated. A series of nanoparticles: nanoshells, nanorods, core-corona nanoparticles and hollow nanoshells, were synthesized and examined to compare their properties and suitability as photothermal agents. In vitro cellular uptake studies of the nanoparticles into prostate cancer cell lines were performed using light scattering microscopy to provide three-dimensional (3D) imaging. Small gold nanoshells (40 nm) displayed the greatest cellular uptake of the nanoparticles studied and were used in photothermal studies. Photothermal treatment of the cancer cell lines with laser irradiation at 800 nm at 4 W on a spot size of 4 mm (FWHM) for 6 or 10 min resulted in an increase in temperature of textasciitilde12 °C and decrease in cell viability of up to 70%. However, in vitro studies combining photothermal therapy with gene therapy targeting HSP27 did not result in additional sensitization of the prostate cancer cells to hyperthermia. |
BibTeX:
@article
{Leung2013,
title = {Investigation of Sub-100 nm Gold Nanoparticles for Laser-Induced Thermotherapy of Cancer}
,author = {Leung, Jennifer P. and Wu, Sherry and Chou, Keng C. and Signorell, Ruth}
,journal = {Nanomaterials}
,publisher = {Multidisciplinary Digital Publishing Institute}
,year = {2013}
,volume = {3}
,number = {1}
,pages = {86--106}
,url = {https://www.mdpi.com/2079-4991/3/1/86}
,doi = {10.3390/nano3010086}
}
|
Cleavage of DNA by Proton-Coupled Electron Transfer to a Photoexcited, Hydrated Ru(II) 1,10-Phenanthroline-5,6-dione Complex,
Poteet SA, Majewski MB, Breitbach ZS, Griffith CA, Singh S, Armstrong DW, Wolf MO and MacDonnell FM,
Journal of the American Chemical Society
135
(7)
, 2419-2422
(2013),
American Chemical Society.
|
| Abstract: Visible light irradiation of a ruthenium(II) quinone-containing complex, [(phen)2Ru(phendione)]2+ (12+), where phendione = 1,10-phenanthroline-5,6-dione, leads to DNA cleavage in an oxygen independent manner. A combination of NMR analyses, transient absorption spectroscopy, and fluorescence measurements in water and acetonitrile reveal that complex 12+ must be hydrated at the quinone functionality, giving [(phen)2Ru(phenH2O)]2+ (1H2O2+, where phenH2O = 1,10-phenanthroline-6-one-5-diol), in order to access a long-lived 3MLCThydrate state (t 360 ns in H2O) which is responsible for DNA cleavage. In effect, hydration at one of the carbonyl functions effectively eliminates the low-energy 3MLCTSQ state (RuIII phen-semiquinone radical anion) as the predominant nonradiative decay pathway. This 3MLCTSQ state is very short-lived (textless1 ns) as expected from the energy gap law for nonradiative decay,(1) and too short-lived to be the photoactive species. The resulting excited state in 1H2O2+* has photophysical properties similar to the 3MLCT state in [Ru(phen)3]2+* with the added functionality of basic sites at the ligand periphery. Whereas [Ru(phen)3]2+* does not show direct DNA cleavage, the deprotonated form of 1H2O2+* does via a proton-coupled electron transfer (PCET) mechanism where the peripheral basic oxygen sites act as the proton acceptor. Analysis of the small molecule byproducts of DNA scission supports the conclusion that cleavage occurs via H-atom abstraction from the sugar moieties, consistent with a PCET mechanism. Complex 12+ is a rare example of a ruthenium complex which ‘turns on’ both reactivity and luminescence upon switching to a hydrated state. |
BibTeX:
@article
{Poteet2013,
title = {Cleavage of DNA by Proton-Coupled Electron Transfer to a Photoexcited, Hydrated Ru(II) 1,10-Phenanthroline-5,6-dione Complex}
,author = {Poteet, Steven A. and Majewski, Marek B. and Breitbach, Zachary S. and Griffith, Cynthia A. and Singh, Shreeyukta and Armstrong, Daniel W. and Wolf, Michael O. and MacDonnell, Frederick M.}
,journal = {Journal of the American Chemical Society}
,publisher = {American Chemical Society}
,year = {2013}
,volume = {135}
,number = {7}
,pages = {2419--2422}
,url = {https://doi.org/10.1021/ja3106863}
,doi = {10.1021/ja3106863}
}
|
Catalytic DNAs That Harness Violet Light To Repair Thymine Dimers in a DNA Substrate,
Barlev A and Sen D,
Journal of the American Chemical Society
135
(7)
, 2596-2603
(2013),
American Chemical Society.
|
| Abstract: UV1C is an in vitro selected catalytic DNA that shows efficient photolyase activity, using light of textless310 nm wavelength to photo-reactivate CPD thymine dimers within a substrate DNA. We show here that a minimal mutational strategy of substituting a guanine analogue, 6MI, for single guanine residues within UV1C extends the DNAzyme’s activity into the violet region of the spectrum. These 6MI point mutant DNAzymes fall into three distinct functional classes, which photo-reactivate the thymine dimer along different pathways. Cumulatively, they reveal the modus operandi of the original UV1C DNAzyme to be a surprisingly versatile one. The interchangeable properties of no less than six of the G?6MI point mutants highlight UV1C’s built-in functional flexibility, which may serve as a starting point for the creation of efficient, visible light-harnessing, photolyase DNAzymes for either the prophylaxis or therapy of UV damage to human skin. |
BibTeX:
@article
{Barlev2013,
title = {Catalytic DNAs That Harness Violet Light To Repair Thymine Dimers in a DNA Substrate}
,author = {Barlev, Adam and Sen, Dipankar}
,journal = {Journal of the American Chemical Society}
,publisher = {American Chemical Society}
,year = {2013}
,volume = {135}
,number = {7}
,pages = {2596--2603}
,url = {https://doi.org/10.1021/ja309638j}
,doi = {10.1021/ja309638j}
}
|
Technical Note: New methodology for measuring viscosities in small volumes characteristic of environmental chamber particle samples,
Renbaum-Wolff L, Grayson JW and Bertram AK,
Atmospheric Chemistry and Physics
13
(2)
, 791-802
(2013),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater Herein, a method for the determination of viscosities of small sample volumes is introduced, with important implications for the viscosity determination of particle samples from environmental chambers (used to simulate atmospheric conditions). The amount of sample needed is textless 1 µl, and the technique is capable of determining viscosities (?) ranging between 10^-3 and 10^3 Pascal seconds (Pa s) in samples that cover a range of chemical properties and with real-time relative humidity and temperature control; hence, the technique should be well-suited for determining the viscosities, under atmospherically relevant conditions, of particles collected from environmental chambers. In this technique, supermicron particles are first deposited on an inert hydrophobic substrate. Then, insoluble beads (textasciitilde1 µm in diameter) are embedded in the particles. Next, a flow of gas is introduced over the particles, which generates a shear stress on the particle surfaces. The sample responds to this shear stress by generating internal circulations, which are quantified with an optical microscope by monitoring the movement of the beads. The rate of internal circulation is shown to be a function of particle viscosity but independent of the particle material for a wide range of organic and organic-water samples. A calibration curve is constructed from the experimental data that relates the rate of internal circulation to particle viscosity, and this calibration curve is successfully used to predict viscosities in multicomponent organic mixtures.textless/ptextgreater |
BibTeX:
@article
{RenbaumWolff2013,
title = {Technical Note: New methodology for measuring viscosities in small volumes characteristic of environmental chamber particle samples}
,author = {Renbaum-Wolff, Lindsay and Grayson, James W. and Bertram, Allan K.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2013}
,volume = {13}
,number = {2}
,pages = {791--802}
,url = {https://www.atmos-chem-phys.net/13/791/2013/}
,doi = {10.5194/acp-13-791-2013}
}
|
Images reveal that atmospheric particles can undergo liquid–liquid phase separations,
You Y, Renbaum-Wolff L, Carreras-Sospedra M, Hanna SJ, Hiranuma N, Kamal S, Smith ML, Zhang X, Weber RJ, Shilling JE, Dabdub D, Martin ST and Bertram AK,
Proceedings of the National Academy of Sciences
109
(33)
, 13188-13193
(2012),
National Academy of Sciences.
|
| Abstract: A large fraction of submicron atmospheric aerosol particles contains both organic material and inorganic salts. As the relative humidity cycles in the atmosphere and the water content of the particles correspondingly changes, these mixed particles can undergo a range of phase transitions, possibly including liquid–liquid phase separation. If liquid–liquid phase separation occurs, the gas-particle partitioning of atmospheric semivolatile organic compounds, the scattering and absorption of solar radiation, and the reactive uptake of gas species on atmospheric particles may be affected, with important implications for climate predictions. The actual occurrence of liquid–liquid phase separation within individual atmospheric particles has been considered uncertain, in large part because of the absence of observations for real-world samples. Here, using optical and fluorescence microscopy, we present images that show the coexistence of two noncrystalline phases for real-world samples collected on multiple days in Atlanta, GA as well as for laboratory-generated samples under simulated atmospheric conditions. These results reveal that atmospheric particles can undergo liquid–liquid phase separations. To explore the implications of these findings, we carried out simulations of the Atlanta urban environment and found that liquid–liquid phase separation can result in increased concentrations of gas-phase NO3 and N2O5 due to decreased particle uptake of N2O5. |
BibTeX:
@article
{You13188,
title = {Images reveal that atmospheric particles can undergo liquid–liquid phase separations}
,author = {You, Yuan and Renbaum-Wolff, Lindsay and Carreras-Sospedra, Marc and Hanna, Sarah J. and Hiranuma, Naruki and Kamal, Saeid and Smith, Mackenzie L. and Zhang, Xiaolu and Weber, Rodney J. and Shilling, John E. and Dabdub, Donald and Martin, Scot T. and Bertram, Allan K.}
,journal = {Proceedings of the National Academy of Sciences}
,publisher = {National Academy of Sciences}
,year = {2012}
,volume = {109}
,number = {33}
,pages = {13188--13193}
,url = {https://www.pnas.org/content/109/33/13188}
,doi = {10.1073/pnas.1206414109}
}
|
Interference spectroscopy with coherent anti-Stokes Raman scattering of noisy broadband pulses,
Shapiro EA, Konorov SO and Milner V,
Journal of Raman Spectroscopy
43
(2)
, 241-247
(2012),
|
| Abstract: We propose a new technique for comparing two Raman active samples. The method employs optical interference of the signals generated via coherent anti-Stokes Raman scattering (CARS) of broadband laser pulses with noisy spectra. It does not require spectrally resolved detection, and no prior knowledge about either the Raman spectrum of the samples or the spectrum of the incident light is needed. We study the proposed method theoretically and demonstrate it in a proof-of-principle experiment on toluene and o-xylene samples. Copyright © 2011 John Wiley & Sons, Ltd. |
BibTeX:
@article
{Shapiro2012,
title = {Interference spectroscopy with coherent anti-Stokes Raman scattering of noisy broadband pulses}
,author = {Shapiro, Evgeny A. and Konorov, Stanislav O. and Milner, Valery}
,journal = {Journal of Raman Spectroscopy}
,year = {2012}
,volume = {43}
,number = {2}
,pages = {241--247}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/jrs.3023}
,doi = {10.1002/jrs.3023}
}
|
Large-area microstructured photomixer as scannable detector of continuous-wave terahertz radiation,
Eshaghi A, Shahabadi M, Chrostowski L and Kamal S,
JOSA B
29
(12)
, 3254-3258
(2012),
Optical Society of America.
|
| Abstract: Detection of continuous-wave (CW) terahertz (THz) radiation is demonstrated using a large-area microstructured photomixer. The photomixer, which has interdigitated electrodes, is utilized in an incoherent detection scheme without any focusing optics for the incoming THz radiation. The large-area microstructured photomixer is driven at a high laser power of 900&xA0;mW, which results in an increased responsivity of 120&xA0;mA/W, in comparison with conventional small-area photomixer detectors. By mapping out the receiving pattern of the photomixer detector, we show that the large-area photomixer is capable of scanning the incident THz beam by changing the incidence angles of the CW laser beams used in the photomixing detection process. We demonstrate a scan range of &xB1;50&xB0;. Moreover, the optimum spot size of the laser beams illuminating the photomixer detector for maximizing the responsivity of the detector is specified. |
BibTeX:
@article
{Eshaghi2012,
title = {Large-area microstructured photomixer as scannable detector of continuous-wave terahertz radiation}
,author = {Eshaghi, Armaghan and Shahabadi, Mahmoud and Chrostowski, Lukas and Kamal, Saeid}
,journal = {JOSA B}
,publisher = {Optical Society of America}
,year = {2012}
,volume = {29}
,number = {12}
,pages = {3254--3258}
,url = {https://www.osapublishing.org/josab/abstract.cfm?uri=josab-29-12-3254}
,doi = {10.1364/JOSAB.29.003254}
}
|
Enhancing strong-field-induced molecular vibration with femtosecond pulse shaping,
Bitter M, Shapiro EA and Milner V,
Physical Review A
86
(4)
, 043421
(2012),
American Physical Society.
|
| Abstract: This work investigates the utility of femtosecond pulse shaping in increasing the efficiency of Raman excitation of molecules in the strong-field interaction regime. We study experimentally and theoretically the effect of pulse shaping on the strength of nonresonant coherent anti-Stokes Raman scattering in iodine vapor at laser intensities exceeding 1013 W/cm2. We show that unlike the perturbative case, shaping strong nonresonant laser pulses can increase the signal strength beyond that observed with the transform-limited excitation. Both adiabatic and nonadiabatic schemes of excitation are explored, and the differences of their potential in increasing the excitation efficiency are discussed. |
BibTeX:
@article
{Bitter2012,
title = {Enhancing strong-field-induced molecular vibration with femtosecond pulse shaping}
,author = {Bitter, Martin and Shapiro, Evengy A. and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2012}
,volume = {86}
,number = {4}
,pages = {043421}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.86.043421}
,doi = {10.1103/PhysRevA.86.043421}
}
|
Photothermal release of small molecules from gold nanoparticles in live cells,
Zandberg WF, Bakhtiari ABS, Erno Z, Hsiao D, Gates BD, Claydon T and Branda NR,
Nanomedicine: Nanotechnology, Biology and Medicine
8
(6)
, 908-915
(2012),
|
| Abstract: The ability of gold (Au) nanoparticles (NPs) to generate heat efficiently by absorbing visible and near-infrared (NIR) light holds great promise as a means to trigger chemical and biochemical events near the NPs. Previous demonstrations show that pulsed laser irradiation can selectively elicit the release of a fluorescent dye covalently anchored to the NP surface through a heat-labile linker without measurably changing the temperature of the surroundings. This article reports that the authors demonstrate the biological efficacy of this approach to photodelivery by showing that the decorated Au NPs are rapidly internalized by cells, are stable under physiological conditions, are nontoxic, and exhibit nonlethal photorelease following exposure to pulsed laser radiation. These observations, further supported by the versatility of our delivery motif, reaffirm the potential for further development of nonlethal photothermal therapeutics and their future relevance to such fields as gene therapy and stem-cell differentiation. From the Clinical Editor The authors further refine previous observations suggesting that Au NP-s may be useful in targeted drug or gene delivery systems. Due to a strong photothermal release effect and their generally low toxicity, Au NP-s may become an important subject of choice in targeted delivery systems. |
BibTeX:
@article
{Zandberg2012,
title = {Photothermal release of small molecules from gold nanoparticles in live cells}
,author = {Zandberg, Wesley F. and Bakhtiari, Amir Bahman Samsam and Erno, Zach and Hsiao, Dennis and Gates, Byron D. and Claydon, Thomas and Branda, Neil R.}
,journal = {Nanomedicine: Nanotechnology, Biology and Medicine}
,year = {2012}
,volume = {8}
,number = {6}
,pages = {908--915}
,url = {http://www.sciencedirect.com/science/article/pii/S154996341100520X}
,doi = {10.1016/j.nano.2011.10.012}
}
|
Synthesis, structure, and luminescent properties of oligothiophene-containing metal–organic frameworks,
Earl LD, Patrick BO and Wolf MO,
CrystEngComm
14
(18)
, 5801-5808
(2012),
The Royal Society of Chemistry.
|
| Abstract: Metal–organic frameworks (MOFs) based on Zn and functionalized bithiophene dicarboxylic acids are reported, [Zn2(L1)2(DMA)2·3 DMF]n (1), [Zn(L2)(DMA)2]n (2), [Zn(L3)(bpe)0.5]n (3), [Zn(L1)(bpe)·2 DMF]n (4), and [Zn3(L2)3(bpe)2·4 DMF · H2O]n(5) (H2L1 = 3,3′-diphenyl-2,2′-bithiophene-5,5′-dicarboxylic acid, H2L2 = 3,3′-dihexyl-2,2′-bithiophene-5,5′-dicarboxylic acid, H2L3 = 2,2′-bithiophene-5,5′-dicarboxylic acid, DMA = dimethylamine, DMF = N,N-dimethylformamide, bpe = trans-1,2-bis(4-pyridyl)ethylene). MOFs 1, 2, and 4 consist of 2-D 4-connected sheets while 3 and 5 are 3-D interpenetrated networks with pcu and (4,6)-connected seh topology, respectively. The emission spectra and lifetimes of 1–5 have been determined: 4 and 5 exhibit reduced emission relative to 1 and 2, respectively, attributed to energy transfer quenching by the bpe, whereas 3 does not exhibit a reduction in emission intensity. Solid state lifetime measurements of 1–5 show that the emission decays are similar to those of the constituent ligands. |
BibTeX:
@article
{Earl2012,
title = {Synthesis, structure, and luminescent properties of oligothiophene-containing metal–organic frameworks}
,author = {Earl, Lyndsey D. and Patrick, Brian O. and Wolf, Michael O.}
,journal = {CrystEngComm}
,publisher = {The Royal Society of Chemistry}
,year = {2012}
,volume = {14}
,number = {18}
,pages = {5801--5808}
,url = {https://pubs.rsc.org/en/content/articlelanding/2012/ce/c2ce25529d}
,doi = {10.1039/C2CE25529D}
}
|
Quantum Resonances in Selective Rotational Excitation of Molecules with a Sequence of Ultrashort Laser Pulses,
Zhdanovich S, Bloomquist C, Floß J, Averbukh IS, Hepburn JW and Milner V,
Physical Review Letters
109
(4)
, 043003
(2012),
American Physical Society.
|
| Abstract: We experimentally investigate the effect of quantum resonance in the rotational excitation of the simplest quantum rotor—a diatomic molecule. Using the techniques of high-resolution femtosecond pulse shaping and rotational state-resolved detection, we measure directly the amount of energy absorbed by molecules interacting with a periodic train of laser pulses, and study their dependence on the train period. We show that the energy transfer is significantly enhanced at quantum resonance, and use this effect to demonstrate selective rotational excitation of two nitrogen isotopologs, 14N2 and 15N2. Moreover, by tuning the period of the pulse train in the vicinity of a fractional quantum resonance, we achieve selective rotational excitation of para- and ortho-isomers of 15N2. |
BibTeX:
@article
{Zhdanovich2012,
title = {Quantum Resonances in Selective Rotational Excitation of Molecules with a Sequence of Ultrashort Laser Pulses}
,author = {Zhdanovich, Sergey and Bloomquist, C. and Floß, Johannes and Averbukh, Ilya Sh. and Hepburn, John W. and Milner, Valery}
,journal = {Physical Review Letters}
,publisher = {American Physical Society}
,year = {2012}
,volume = {109}
,number = {4}
,pages = {043003}
,url = {https://link.aps.org/doi/10.1103/PhysRevLett.109.043003}
,doi = {10.1103/PhysRevLett.109.043003}
}
|
Coherent rovibrational revivals in a thermal molecular ensemble,
Bitter M, Shapiro EA and Milner V,
Physical Review A
85
(4)
, 043410
(2012),
American Physical Society.
|
| Abstract: We report an experimental and theoretical study of the evolution of vibrational coherence in a thermal ensemble of nitrogen molecules. Rotational dephasing and rephasing of the vibrational coherence is detected by coherent anti-Stokes Raman scattering. The existence of rovibrational coupling and the discrete energy spectrum of the rotational bath lead to a whole new class of full and fractional rovibrational revivals. Following the rich rovibrational dynamics on a nanosecond time scale with subpicosecond time resolution enables us to determine the second-order rovibrational constant ?e and assess new possibilities of controlling decoherence. |
BibTeX:
@article
{Bitter2012a,
title = {Coherent rovibrational revivals in a thermal molecular ensemble}
,author = {Bitter, Martin and Shapiro, Evengy A. and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2012}
,volume = {85}
,number = {4}
,pages = {043410}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.85.043410}
,doi = {10.1103/PhysRevA.85.043410}
}
|
STEADY AND TRANSIENT DROPLET DISPERSION IN AN AIR-ASSIST INTERNALLY MIXING CONE ATOMIZER,
Aliabadi AA, Lim KWJ, Rogak SN and Green SI,
Atomization and Sprays
21
(12)
, 1009-1031
(2011),
|
BibTeX:
@article
{Aliabadi2011,
title = {STEADY AND TRANSIENT DROPLET DISPERSION IN AN AIR-ASSIST INTERNALLY MIXING CONE ATOMIZER}
,author = {Amir Abbas Aliabadi and Kelly W. J. Lim and Steven N. Rogak and Sheldon I. Green}
,journal = {Atomization and Sprays}
,year = {2011}
,volume = {21}
,number = {12}
,pages = {1009--1031}
}
|
Control of Molecular Rotation with a Chiral Train of Ultrashort Pulses,
Zhdanovich S, Milner AA, Bloomquist C, Floß J, Averbukh IS, Hepburn JW and Milner V,
Physical Review Letters
107
(24)
, 243004
(2011),
American Physical Society.
|
| Abstract: Trains of ultrashort laser pulses separated by the time of rotational revival (typically, tens of picoseconds) have been exploited for creating ensembles of aligned molecules. In this work we introduce a chiral pulse train—a sequence of linearly polarized pulses with the polarization direction rotating from pulse to pulse by a controllable angle. The chirality of such a train, expressed through the period and direction of its polarization rotation, is used as a new control parameter for achieving selectivity and directionality of laser-induced rotational excitation. The method employs chiral trains with a large number of pulses separated on the time scale much shorter than the rotational revival (a few hundred femtosecond), enabling the use of conventional pulse shapers. |
BibTeX:
@article
{Zhdanovich2011a,
title = {Control of Molecular Rotation with a Chiral Train of Ultrashort Pulses}
,author = {Zhdanovich, Sergey and Milner, Alexander A. and Bloomquist, C. and Floß, Johannes and Averbukh, Ilya Sh. and Hepburn, John W. and Milner, Valery}
,journal = {Physical Review Letters}
,publisher = {American Physical Society}
,year = {2011}
,volume = {107}
,number = {24}
,pages = {243004}
,url = {https://link.aps.org/doi/10.1103/PhysRevLett.107.243004}
,doi = {10.1103/PhysRevLett.107.243004}
}
|
Strong-field effects in Rabi oscillations between a single state and a superposition of states,
Zhdanovich S, Hepburn JW and Milner V,
Physical Review A
84
(5)
, 053428
(2011),
American Physical Society.
|
| Abstract: Rabi oscillations of quantum population are known to occur in two-level systems driven by spectrally narrow laser fields. In this work we study Rabi oscillations induced by shaped broadband femtosecond laser pulses. Due to the broad spectral width of the driving field, the oscillations are initiated between a ground state and a coherent superposition of excited states, or a “wave packet,” rather than a single excited state. Our experiments reveal an intricate dependence of the wave-packet phase on the intensity of the laser field. We confirm numerically that the effect is associated with the strong-field nature of the interaction and provide a qualitative picture by invoking a simple theoretical model. |
BibTeX:
@article
{Zhdanovich2011,
title = {Strong-field effects in Rabi oscillations between a single state and a superposition of states}
,author = {Zhdanovich, Sergey and Hepburn, John W. and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2011}
,volume = {84}
,number = {5}
,pages = {053428}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.84.053428}
,doi = {10.1103/PhysRevA.84.053428}
}
|
Prospects of coherent control in turbid media: Bounds on focusing broadband laser pulses,
Shapiro EA, Drane TM and Milner V,
Physical Review A
84
(5)
, 053807
(2011),
American Physical Society.
|
| Abstract: We study the prospects of controlling transmission of broadband and bichromatic laser pulses through turbid samples. The ability to focus transmitted broadband light is limited via both the scattering properties of the medium and the technical characteristics of the experimental setup. There are two time scales given by pulse stretching in the near- and far-field regions which define the maximum bandwidth of a pulse amenable to focusing. In the geometric-optics regime of wave propagation in the medium, a single setup can be optimal for focusing light at frequencies ? and n? simultaneously, providing the basis for the 1+n coherent quantum control. Beyond the regime of geometric optics, we discuss a simple solution for the shaping, which provides the figure of merit for one’s ability to simultaneously focus several transmission modes. |
BibTeX:
@article
{Shapiro2011,
title = {Prospects of coherent control in turbid media: Bounds on focusing broadband laser pulses}
,author = {Shapiro, Evgeny A. and Drane, Thomas M. and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2011}
,volume = {84}
,number = {5}
,pages = {053807}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.84.053807}
,doi = {10.1103/PhysRevA.84.053807}
}
|
Ligand-Triplet-Fueled Long-Lived Charge Separation in Ruthenium(II) Complexes with Bithienyl-Functionalized Ligands,
Majewski MB, Tacconi NRd, MacDonnell FM and Wolf MO,
Inorganic Chemistry
50
(20)
, 9939-9941
(2011),
American Chemical Society.
|
| Abstract: Ruthenium(II) polypyridyl complexes with pendant bithienyl ligands exhibiting unusually long-lived (t 3–7 µs) charge-separated excited states and a large amount of stored energy (?G° 2.0 eV) are reported. A long-lived ligand-localized triplet acts as an energy reservoir to fuel population of an interligand charge-transfer state via an intermediate metal-to-ligand charge-transfer state in these complexes. |
BibTeX:
@article
{Majewski2011,
title = {Ligand-Triplet-Fueled Long-Lived Charge Separation in Ruthenium(II) Complexes with Bithienyl-Functionalized Ligands}
,author = {Majewski, Marek B. and Tacconi, Norma R. de and MacDonnell, Frederick M. and Wolf, Michael O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2011}
,volume = {50}
,number = {20}
,pages = {9939--9941}
,url = {https://doi.org/10.1021/ic201895y}
,doi = {10.1021/ic201895y}
}
|
Review of Super-Resolution Fluorescence Microscopy for Biology,
Leung BO and Chou KC,
Applied Spectroscopy
65
(9)
, 967-980
(2011),
SAGE Publications Ltd STM.
|
| Abstract: Several methodologies have been developed over the past several years for super-resolution fluorescence microscopy including saturated structured-illumination microscopy (SSIM), stimulated emission depletion microscopy (STED), photoactivated localization microscopy (PALM), fluorescence photoactivation localization microscopy (FPALM), and stochastic optical reconstruction microscopy (STORM). While they have shown great promise for biological research, these techniques all have individual strengths and weaknesses. This review will describe the basic principles for achieving super resolution, demonstrate some applications in biology, and provide an overview of technical considerations for implementing these methods. |
BibTeX:
@article
{Leung2011,
title = {Review of Super-Resolution Fluorescence Microscopy for Biology}
,author = {Leung, Bonnie O. and Chou, Keng C.}
,journal = {Applied Spectroscopy}
,publisher = {SAGE Publications Ltd STM}
,year = {2011}
,volume = {65}
,number = {9}
,pages = {967--980}
,url = {https://journals.sagepub.com/doi/abs/10.1366/11-06398}
,doi = {10.1366/11-06398}
}
|
Charge Transfer and Intraligand Excited State Interactions in Platinum-Sensitized Dithienylethenes,
Roberts MN, Nagle JK, Majewski MB, Finden JG, Branda NR and Wolf MO,
Inorganic Chemistry
50
(11)
, 4956-4966
(2011),
American Chemical Society.
|
| Abstract: The photophysical behavior for two photochromic Pt-terpyridine acetylide complexes containing pendant dithienylethenes (DTEs) bound to the metal through the alkynyl linkage is presented. Selective excitation of the Pt complex with visible light resulted in the metal-sensitized ring closing of the DTE unit. The central purpose of this study was to understand how excited state interactions govern the photophysics by correlating differences in the linkage of the two components with differences in the intramolecular energy transfer processes that occur between the Pt complex and the DTE. A series of model complexes without photochromic ligands were prepared and studied to elucidate the contributions of the triplet metal-to-ligand charge transfer and triplet intraligand states. It is demonstrated that reducing the orbital overlap of the metal-based and intraligand states by lengthening the linkage and eliminating a conjugated pathway is effective at dramatically decreasing the efficiency of intramolecular energy transfer. This is evidenced by the appearance of Pt-terpyridine based phosphorescence and a significant decrease in the observed rate of metal-sensitized ring closing of the DTE. |
BibTeX:
@article
{Roberts2011,
title = {Charge Transfer and Intraligand Excited State Interactions in Platinum-Sensitized Dithienylethenes}
,author = {Roberts, Matthew N. and Nagle, Jeffrey K. and Majewski, Marek B. and Finden, Jeremy G. and Branda, Neil R. and Wolf, Michael O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2011}
,volume = {50}
,number = {11}
,pages = {4956--4966}
,url = {https://doi.org/10.1021/ic200200j}
,doi = {10.1021/ic200200j}
}
|
Time- and frequency-resolved detection of atomic coherence in the regime of strong-field interaction with intense femtosecond laser pulses,
Konorov SO, Hepburn JW and Milner V,
Physical Review A
83
(3)
, 033417
(2011),
American Physical Society.
|
| Abstract: Understanding the effect of strong laser pulses on the evolution of an atomic or molecular wave function is important in the context of coherent control in the strong-field regime, when power broadening and dynamic Stark shifts become comparable with or bigger than the bandwidth of the control field. We experimentally demonstrate the method of complete characterization of a complex-valued amplitude of a quantum state driven by a strong two-photon field. The method is based on coherent scattering of a weak probe pulse from the strong-field-induced atomic coherence, followed by the detection of the time- and frequency-resolved parametric four-wave-mixing signal. We show that the proposed technique corresponds to a cross-correlation frequency-resolved optical gating (XFROG) of the highly perturbed evolution of an atomic quantum state. Utilizing the XFROG retrieval algorithm, we determine both the amplitude and phase of an atomic wave function at any time moment throughout the interaction with the driving field. The direct retrieval of the time-dependent phase of the wave function, rather than the population dynamics only, enables us to observe the strong-field effects with arbitrary time and frequency resolution. |
BibTeX:
@article
{Konorov2011,
title = {Time- and frequency-resolved detection of atomic coherence in the regime of strong-field interaction with intense femtosecond laser pulses}
,author = {Konorov, Stanislav. O. and Hepburn, John W. and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2011}
,volume = {83}
,number = {3}
,pages = {033417}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.83.033417}
,doi = {10.1103/PhysRevA.83.033417}
}
|
Laser-Patterned Super-Hydrophobic Pure Metallic Substrates: Cassie to Wenzel Wetting Transitions,
Kietzig A-M, Mirvakili MN, Kamal S, Englezos P and Hatzikiriakos SG,
Journal of Adhesion Science and Technology
25
(20)
, 2789-2809
(2011),
Taylor & Francis.
|
| Abstract: A femtosecond laser was used to create microstructures on very pure metal surfaces. The irradiated samples initially showed super-hydrophilic behavior. With time and exposure to ambient air the contact angle increased to about 160° with very low hysteresis. The surfaces supported the Cassie and Wenzel wetting states, depending on the technique used to deposit the water droplets. The created surface morphologies were idealized with a geometric model that is an assembly of densely packed cylindrical pillars with semispherical caps. Using this geometric model for calculation of the surface roughness, a theoretical Young contact angle of about 99° was calculated for all samples from the Wenzel and Cassie–Baxter equations. While the value of 99° significantly differs from the measured hydrophilic contact angles on the polished pure metallic samples, it indicates that a laser-induced surface reaction must be responsible for the evolution of contact angles to super-hydrophobic ones and that this phenomenon is independent of the type of metal. |
BibTeX:
@article
{Kietzig2011,
title = {Laser-Patterned Super-Hydrophobic Pure Metallic Substrates: Cassie to Wenzel Wetting Transitions}
,author = {Kietzig, Anne-Marie and Mirvakili, Mehr Negar and Kamal, Saeid and Englezos, Peter and Hatzikiriakos, Savvas G.}
,journal = {Journal of Adhesion Science and Technology}
,publisher = {Taylor & Francis}
,year = {2011}
,volume = {25}
,number = {20}
,pages = {2789--2809}
,url = {https://www.tandfonline.com/doi/abs/10.1163/016942410X549988}
,doi = {10.1163/016942410X549988}
}
|
Nanopatterned Metallic Surfaces: Their Wettability and Impact on Ice Friction,
Kietzig A-M, Mirvakili MN, Kamal S, Englezos P and Hatzikiriakos SG,
Journal of Adhesion Science and Technology
25
(12)
, 1293-1303
(2011),
Taylor & Francis.
|
| Abstract: A distinct surface microstructure was created on the surface of metal alloys and highly pure metals by using a one-step femtosecond laser process. After irradiation the surfaces show initially superhydrophilic behavior with complete wetting. With time and exposure to ambient air, however, the measured contact angles on these surfaces increase significantly. Eventually, all surfaces become hydrophobic and support Cassie-like hydrophobicity with contact angles beyond 150° and very low hysteresis. The increase in contact angle with time correlates with the amount of carbon detected on the irradiated surface, which suggests that the time dependency of the surface wettability depends on the combined effect of surface morphology and surface chemistry. The nanopatterned superhydrophobic substrates were tested in ice friction tests. At temperatures close to the melting point and relatively high speeds of the metal slider, the laser created nanoroughness and hydrophobicity significantly decrease ice friction. This decrease in friction is attributed to the suppression of capillary bridges between the slider and ice surface, which contributes considerably to the overall frictional resistance. |
BibTeX:
@article
{Kietziga2011,
title = {Nanopatterned Metallic Surfaces: Their Wettability and Impact on Ice Friction}
,author = {Kietzig, Anne-Marie and Mirvakili, Mehr Negar and Kamal, Saeid and Englezos, Peter and Hatzikiriakos, Savvas G.}
,journal = {Journal of Adhesion Science and Technology}
,publisher = {Taylor & Francis}
,year = {2011}
,volume = {25}
,number = {12}
,pages = {1293--1303}
,url = {https://doi.org/10.1163/016942411X555872}
,doi = {10.1163/016942411X555872}
}
|
Ground-based remote sensing of an elevated forest fire aerosol layer at Whistler, BC: implications for interpretation of mountaintop chemistry,
McKendry IG, Gallagher J, Campuzano Jost P, Bertram AK, Strawbridge K, Leaitch R and Macdonald AM,
Atmospheric Chemistry and Physics
10
(23)
, 11921-11930
(2010),
Copernicus GmbH.
|
| Abstract: textlessptextgreatertextlessstrongtextgreaterAbstract.textless/strongtextgreater On 30 August 2009, intense forest fires in interior British Columbia (BC) coupled with winds from the east and northeast resulted in transport of a broad forest fire plume across southwestern BC. The physico-chemical and optical characteristics of the plume as observed from Saturna Island (AERONET), CORALNet-UBC and the Whistler Mountain air chemistry facility were consistent with forest fire plumes that have been observed elsewhere in continental North America. However, the importance of three-dimensional transport in relation to the interpretation of mountaintop chemistry observations is highlighted on the basis of deployment of both a CL31 ceilometer and a single particle mass spectrometer (SPMS) in a mountainous setting. The SPMS is used to identify the biomass plume based on levoglucosan and potassium markers. Data from the SPMS are also used to show that the biomass plume was correlated with nitrate, but not correlated with sulphate or sodium. This study not only provides baseline measurements of biomass burning plume physico-chemical characteristics in western Canada, but also highlights the importance of lidar remote sensing methods in the interpretation of mountaintop chemistry measurements.textless/ptextgreater |
BibTeX:
@article
{McKendry2010,
title = {Ground-based remote sensing of an elevated forest fire aerosol layer at Whistler, BC: implications for interpretation of mountaintop chemistry}
,author = {McKendry, I. G. and Gallagher, J. and Campuzano Jost, Pedro and Bertram, Allan K. and Strawbridge, K. and Leaitch, R. and Macdonald, A. M.}
,journal = {Atmospheric Chemistry and Physics}
,publisher = {Copernicus GmbH}
,year = {2010}
,volume = {10}
,number = {23}
,pages = {11921--11930}
,url = {https://www.atmos-chem-phys.net/10/11921/2010/}
,doi = {10.5194/acp-10-11921-2010}
}
|
Effects of Hydrogen Addition on High-Pressure Nonpremixed Natural Gas Combustion,
Wu N, McTaggart-Cowan GP, Bushe WK and Davy MH,
Combustion Science and Technology
183
(1)
, 20-42
(2010),
Taylor & Francis.
|
| Abstract: The effects of hydrogen addition on the ignition and combustion of a high-pressure methane jet in a quiescent charge of high-temperature, medium-pressure air were investigated numerically and experimentally. Subsequently, the results of these two fundamental studies were applied to the interpretation of combustion and emissions measurements from a pilot-ignited natural gas engine fueled with similar fuels. Whereas, under quiescent conditions, the influence of hydrogen addition on the autoignition delay time of the gaseous jet was small, a markedly greater effect was observed in the more complex environment of the research engine. Similarly, in the two fundamental studies, the addition of hydrogen to the methane fuel resulted in a reduction of NOx emissions, whereas increased levels of NOx emissions were observed from the engine, highlighting the difference between the autoignition and pilot-ignition process. |
BibTeX:
@article
{Wu2010,
title = {Effects of Hydrogen Addition on High-Pressure Nonpremixed Natural Gas Combustion}
,author = {Wu, N. and McTaggart-Cowan, G. P. and Bushe, W. K. and Davy, M. H.}
,journal = {Combustion Science and Technology}
,publisher = {Taylor & Francis}
,year = {2010}
,volume = {183}
,number = {1}
,pages = {20--42}
,url = {https://doi.org/10.1080/00102202.2010.496381}
,doi = {10.1080/00102202.2010.496381}
}
|
Photothermal Release of Single-Stranded DNA from the Surface of Gold Nanoparticles Through Controlled Denaturating and Au-S Bond Breaking,
Poon L, Zandberg WF, Hsiao D, Erno Z, Sen D, Gates BD and Branda NR,
ACS Nano
4
(11)
, 6395-6403
(2010),
American Chemical Society.
|
| Abstract: Photothermal release of DNA from gold nanoparticles either by thermolysis of the Au-S bonds used to anchor the oligonucleotides to the nanoparticle or by thermal denaturation has great therapeutic potential, however, both processes have limitations (a decreased particle stability for the former process and a prohibitively slow rate of release for the latter). Here we show that these two mechanisms are not mutually exclusive and can be controlled by adjusting laser power and ionic strength. We show this using two different double-stranded (ds)DNA-nanoparticle conjugates, in which either the anchored sense strand or the complementary antisense strand was labeled with a fluorescent marker. The amounts of release due to the two mechanisms were evaluated using fluorescence spectroscopy and capillary electrophoresis, which showed that irradiation of the decorated particles in 200 mM NaOAc containing 10 mM Mg(OAc)2 with a pulsed 532 nm laser operating at 100 mW favors denaturation over Au-S cleavage to an extent of more than six-to-one. Due to the use of a pulsed laser, the process occurs on the order of minutes rather than hours, which is typical for continuous wave lasers. These findings encourage continued research toward developing photothermal gene therapeutics. |
BibTeX:
@article
{Poon2010,
title = {Photothermal Release of Single-Stranded DNA from the Surface of Gold Nanoparticles Through Controlled Denaturating and Au-S Bond Breaking}
,author = {Poon, Lester and Zandberg, Wesley F. and Hsiao, Dennis and Erno, Zach and Sen, Dipankar and Gates, Byron D. and Branda, Neil R.}
,journal = {ACS Nano}
,publisher = {American Chemical Society}
,year = {2010}
,volume = {4}
,number = {11}
,pages = {6395--6403}
,url = {https://doi.org/10.1021/nn1016346}
,doi = {10.1021/nn1016346}
}
|
Coherent Raman spectroscopy through one-dimensional random scattering medium,
Drane TM, Hepburn JW and Milner V,
Journal of Modern Optics
57
(19)
, 1928-1935
(2010),
Taylor & Francis.
|
| Abstract: We investigate the possibility of implementing coherent anti-Stokes Raman spectroscopy (CARS) with a single laser beam passed through a one-dimensional scattering object. The effect of the random scattering is emulated by shaping the laser pulses with a spectral mask corresponding to the transmission spectrum of a random layered medium. Raman resonances are retrieved through correlation analysis of the CARS spectrum. We study the effect of the scattering parameters on the resolution of the method, and show that improvement of the spectroscopic sensitivity can be achieved by compensating the phase distortions introduced by the scatterer. |
BibTeX:
@article
{Drane2010,
title = {Coherent Raman spectroscopy through one-dimensional random scattering medium}
,author = {Drane, Thomas M. and Hepburn, John W. and Milner, Valery}
,journal = {Journal of Modern Optics}
,publisher = {Taylor & Francis}
,year = {2010}
,volume = {57}
,number = {19}
,pages = {1928--1935}
,url = {https://doi.org/10.1080/09500340.2010.506010}
,doi = {10.1080/09500340.2010.506010}
}
|
Studies of one and two component aerosols using IR/VUV single particle mass spectrometry: Insights into the vaporization process and quantitative limitations,
Simpson EA, Campuzano-Jost P, Hanna SJ, Kanan KMM, Hepburn JW, Blades MW and Bertram AK,
Physical Chemistry Chemical Physics
12
(37)
, 11565-11575
(2010),
The Royal Society of Chemistry.
|
| Abstract: This paper presents the studies of one and two component particles using a CO2 laser for vaporization and VUV ionization in an ion trap mass spectrometer. The degree of fragmentation for a one component system was demonstrated to be a function of CO2 laser energy. In a two component system, the degree of fragmentation was shown to be a function of the particle composition. This observation indicates that the analysis of mixed particles may be far more complicated than anticipated for a two step process with soft vaporization. In addition to showing that fragmentation is a function of CO2 laser energy and particle composition, we also show that a key parameter that determines the extent of fragmentation is the energy absorbed by the particle during desorption. The ionization delay profile in a one component system is also shown to be strongly dependent on the vaporization energy. In a two component system, the delay profile is shown to strongly depend on the composition of the particle. The combined data suggest that the key parameter that governs the delay profile is the energy absorbed by the particle during desorption. This finding has implications for potential field measurements. Finally, for a two component system where the absorption crosssections are different, the change in the degree of fragmentation with particle composition resulted in a non-linear dependence of ion signal on composition. This makes any attempt at quantification difficult. |
BibTeX:
@article
{Simpson2010,
title = {Studies of one and two component aerosols using IR/VUV single particle mass spectrometry: Insights into the vaporization process and quantitative limitations}
,author = {Simpson, Emily A. and Campuzano-Jost, Pedro and Hanna, Sarah J. and Kanan, Khalid M. M. and Hepburn, John W. and Blades, Michael W. and Bertram, Allan K.}
,journal = {Physical Chemistry Chemical Physics}
,publisher = {The Royal Society of Chemistry}
,year = {2010}
,volume = {12}
,number = {37}
,pages = {11565--11575}
,url = {https://pubs.rsc.org/en/content/articlelanding/2010/cp/c0cp00462f}
,doi = {10.1039/C0CP00462F}
}
|
Application of stimulated Raman pumping toward the first study of chemical reaction dynamics of the muonium atom with H2*,
Sukhorukov O, Bakule P, Matsuda Y, Kamal S, Momose T and Fleming D,
physica status solidi c
6
(S1)
, S263-S266
(2009),
|
| Abstract: The chemical reaction of interest, from the field of µSR spectroscopy, is that of the muonium atom (Mu) with molecular hydrogen in its first vibrational excited state. The stimulated Raman pumping (SRP) technique has been used to prepare H2 in its ? = 1 state in a series of off-line experiments at the LASIR Lab at UBC. Three different SRP excitation schemes employing the second harmonic of a Nd:YAG laser have been analysed in connection with this application, for 5.5, 13, and 26 cm-long reaction cells. The laser energy varied from 80 to 550 mJ/pulse (or from 0.07 GW/cm2 to 0.46 GW/cm2) at a 10 Hz repetition rate. The importance of injection seeding of the Nd:YAG laser for efficient molecular excitation is shown. The major challenge of this experiment was to ensure a homogeneous excitation over a large volume (few cm3) while achieving a high amount of vibrationally excited H2 (3-15 Torr). This is demanded by the requirements of superposition of a pulsed muon beam with the laser beam and the expected rate constant of the Mu + H2*(?=1) ?MuH + H reaction. In this endeavour it was also of interest to explore the effect of added moderator gas to the hydrogen and so the effect of Ar/Xe moderator on the efficiency of hydrogen pumping for different SRP excitation schemes is also shown. (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) |
BibTeX:
@article
{Sukhorukov2009,
title = {Application of stimulated Raman pumping toward the first study of chemical reaction dynamics of the muonium atom with H2*}
,author = {Sukhorukov, Oleksandr and Bakule, Pavel and Matsuda, Yasuyuki and Kamal, Saeid and Momose, Takamasa and Fleming, Donald}
,journal = {physica status solidi c}
,year = {2009}
,volume = {6}
,number = {S1}
,pages = {S263--S266}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/pssc.200881345}
,doi = {10.1002/pssc.200881345}
}
|
SHAPING AND MONITORING MOLECULAR WAVEPACKETS WITH SHAPED FEMTOSECOND PULSES,
Milner V,
Physics in Canada / Vol. 65, No. 2
(2009),
|
| Abstract: We briefly review the latest developments in
using high-power ultra-short laser pulses as an efficient tool for controlling and monitoring molecular quantum states. |
BibTeX:
@article
{MILNER,
title = {SHAPING AND MONITORING MOLECULAR WAVEPACKETS WITH SHAPED FEMTOSECOND PULSES}
,author = {Milner, Valery}
,journal = {Physics in Canada / Vol. 65, No. 2}
,year = {2009}
}
|
Characterization of transient molecular vibration excited with shaped femtosecond pulses,
Konorov SO, Xu XG, Hepburn JW and Milner V,
The Journal of chemical physics
130
(23)
, 234505
(2009),
American Institute of Physics.
|
| Abstract: We study vibrational dynamics of molecules interacting with spectrally shaped broadband laser pulses. After performing a single measurement based on cross-correlation frequency resolved optical gating of molecular vibration, complete evolution of the complex-valued quantum coherence between the vibrational states is reconstructed with variable time and frequency resolution. The ability to change the resolution in the analysis of the transient molecular dynamics without repeating the experiment or changing experimental parameters is useful in designing and understanding various schemes of controlling quantum states of molecules. |
BibTeX:
@article
{Konorov2009,
title = {Characterization of transient molecular vibration excited with shaped femtosecond pulses}
,author = {Konorov, Stanislav O. and Xu, Xiaoji G. and Hepburn, John W. and Milner, Valery}
,journal = {The Journal of chemical physics}
,publisher = {American Institute of Physics}
,year = {2009}
,volume = {130}
,number = {23}
,pages = {234505}
}
|
An Efficient Method Based on the Photothermal Effect for the Release of Molecules from Metal Nanoparticle Surfaces,
Bakhtiari ABS, Hsiao D, Jin G, Gates BD and Branda NR,
Angewandte Chemie International Edition
48
(23)
, 4166-4169
(2009),
|
| Abstract: Please release me: The heat generated when metal nanoparticles absorb light results in a significant increase in the temperature of the environment around the particles and is used to selectively break bonds within a molecular system anchored to the nanoparticle surface (see picture). This process represents an advantageous and more universal method to deliver chemicals locally, while avoiding excessive tissue damage. |
BibTeX:
@article
{Bakhtiari2009,
title = {An Efficient Method Based on the Photothermal Effect for the Release of Molecules from Metal Nanoparticle Surfaces}
,author = {Bakhtiari, Amir Bahman Samsam and Hsiao, Dennis and Jin, Guoxia and Gates, Byron D. and Branda, Neil R.}
,journal = {Angewandte Chemie International Edition}
,year = {2009}
,volume = {48}
,number = {23}
,pages = {4166--4169}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/anie.200805303}
,doi = {10.1002/anie.200805303}
}
|
Complete transfer of populations from a single state to a preselected superposition of states using piecewise adiabatic passage: Experiment,
Zhdanovich S, Shapiro EA, Hepburn JW, Shapiro M and Milner V,
Physical Review A
80
(6)
, 063405
(2009),
American Physical Society.
|
| Abstract: We demonstrate a method of adiabatic population transfer from a single quantum state into a coherent superposition of states. The transfer is executed with femtosecond pulses, spectrally shaped in a simple and intuitive manner, which does not require iterative feedback-controlled loops. In contrast to nonadiabatic methods of excitation, our approach is not sensitive to the exact value of laser intensity. We show that the population transfer is complete, and analyze the possibility of controlling the relative phases and amplitudes of the excited eigenstates. We discuss the limitations of the proposed control methods due to the dynamic level shifts and suggest ways of reducing their influence. |
BibTeX:
@article
{Zhdanovich2009,
title = {Complete transfer of populations from a single state to a preselected superposition of states using piecewise adiabatic passage: Experiment}
,author = {Zhdanovich, Sergey and Shapiro, Evengy A. and Hepburn, John W. and Shapiro, M. and Milner, Valery}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2009}
,volume = {80}
,number = {6}
,pages = {063405}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.80.063405}
,doi = {10.1103/PhysRevA.80.063405}
}
|
Subdiffraction-Limit Two-Photon Fluorescence Microscopy for GFP-Tagged Cell Imaging,
Li Q, Wu S and Chou KC,
Biophysical Journal
97
(12)
, 3224-3228
(2009),
|
| Abstract: We report applications of two-photon excitation fluorescence (2PEF) microscopy with subdiffraction-limit resolution for green-fluorescent-protein-tagged cell imaging. The microscope integrates 2PEF microscopy and stimulated emission depletion microscopy in one microscope that has the benefits of both techniques: intrinsic three-dimensional resolution, confined photobleaching, and subdiffraction-limit resolution. The subdiffraction-limit resolution was demonstrated by resolving green-fluorescent-protein-tagged caveolar vesicles located within a distance shorter than the diffraction limit of a regular 2PEF microscope, which is 250 nm even with the best optics. The full width at half-maximum of the effective point-spread function for the 2PEF microscope was estimated to be 54 nm. |
BibTeX:
@article
{Li2009,
title = {Subdiffraction-Limit Two-Photon Fluorescence Microscopy for GFP-Tagged Cell Imaging}
,author = {Li, Qifeng and Wu, Sherry and Chou, Keng C.}
,journal = {Biophysical Journal}
,year = {2009}
,volume = {97}
,number = {12}
,pages = {3224--3228}
,url = {http://www.sciencedirect.com/science/article/pii/S0006349509015227}
,doi = {10.1016/j.bpj.2009.09.038}
}
|
Selective Recognition of Rituximab-Functionalized Gold Nanoparticles by Lymphoma Cells Studied with 3D Imaging,
Weiss A, Preston TC, Popov J, Li Q, Wu S, Chou KC, Burt HM, Bally MB and Signorell R,
The Journal of Physical Chemistry C
113
(47)
, 20252-20258
(2009),
American Chemical Society.
|
| Abstract: Several types of multivalent therapeutic antibody constructs have recently been described which exhibit an increased efficacy compared to free, bivalent antibody. For example, it has been shown that rituximab-coupled liposomes (devoid of encapsulated drug) show a stronger response than equal amounts of monomeric rituximab, supposedly due to the ability of the multivalent complex to hyper-cross-link its target in the plasma membrane. We sought to create a new type of multivalent antibody construct using gold nanoparticles, where rituximab is bound to the particle surface through a strong covalent bond. In the present study, rituximab-conjugated gold particles have been prepared with the aim of identifying suitable formulations for use in studies assessing the therapeutic potential of these novel formulations. Different types of rituximab-conjugated particles are prepared and characterized. The size of the particles, as well as the type of functionalization, is varied. In vitro studies with CD-20 positive human mantle cell lymphoma cells and CD-20 negative breast cancer cells combined with three-dimensional (3D) imaging allowed us to select an optimized rituximab-gold system for further studies. Selective recognition of these rituximab nanocarriers by lymphoma cells is demonstrated. |
BibTeX:
@article
{Weiss2009,
title = {Selective Recognition of Rituximab-Functionalized Gold Nanoparticles by Lymphoma Cells Studied with 3D Imaging}
,author = {Weiss, Angelina and Preston, Thomas C. and Popov, Jesse and Li, Qifeng and Wu, Sherry and Chou, Keng C. and Burt, Helen M. and Bally, Marcel B. and Signorell, Ruth}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2009}
,volume = {113}
,number = {47}
,pages = {20252--20258}
,url = {https://doi.org/10.1021/jp907423z}
,doi = {10.1021/jp907423z}
}
|
Successful Bifunctional Photoswitching and Electronic Communication of Two Platinum(II) Acetylide Bridged Dithienylethenes,
Roberts MN, Carling C-J, Nagle JK, Branda NR and Wolf MO,
Journal of the American Chemical Society
131
(46)
, 16644-16645
(2009),
American Chemical Society.
|
| Abstract: Coordinating two dithienylethenes to a platinum center results in the reversible ring closure of both photochromic units in a model for a photoresponsive p-conjugated polymer. This system demonstrates how metal-sensitized photochemistry, from a triplet excited state, circumvents the problems associated with other multicomponent photochromic systems, where significant electronic interactions in the ground state and singlet excited state prevent full photoswitching. Changes in charge-transfer behavior based upon conversion of both dithienylethenes to their ring-closed forms illustrate how photomodulation of conductivity through a conjugated polymer might be achieved using Pt-bis(acetylide)s. |
BibTeX:
@article
{Roberts2009,
title = {Successful Bifunctional Photoswitching and Electronic Communication of Two Platinum(II) Acetylide Bridged Dithienylethenes}
,author = {Roberts, Matthew N. and Carling, Carl-Johan and Nagle, Jeffrey K. and Branda, Neil R. and Wolf, Michael O.}
,journal = {Journal of the American Chemical Society}
,publisher = {American Chemical Society}
,year = {2009}
,volume = {131}
,number = {46}
,pages = {16644--16645}
,url = {https://doi.org/10.1021/ja907434x}
,doi = {10.1021/ja907434x}
}
|
Simultaneous composition and thickness measurement of paper using terahertz time-domain spectroscopy,
Mousavi P, Haran F, Jez D, Santosa F and Dodge JS,
Applied Optics
48
(33)
, 6541-6546
(2009),
Optical Society of America.
|
| Abstract: We present a noncontact method for quantitative composition and thickness monitoring of flat sheet products using terahertz time-domain spectroscopy. We apply the method to obtain simultaneous measurement of thickness and moisture content of paper sheets. The paper is modeled as an effective medium of water mixed with fibers, and model parameters are estimated from fits to the measured transmission amplitude. We demonstrate the method on two different paper samples and obtain uncertainties that are comparable with existing sensor technology. Monte Carlo simulations indicate that these uncertainties can be reduced further by at least an order of magnitude. |
BibTeX:
@article
{Mousavi2009,
title = {Simultaneous composition and thickness measurement of paper using terahertz time-domain spectroscopy}
,author = {Mousavi, Payam and Haran, Frank and Jez, David and Santosa, Fadil and Dodge, John Steven}
,journal = {Applied Optics}
,publisher = {Optical Society of America}
,year = {2009}
,volume = {48}
,number = {33}
,pages = {6541--6546}
,url = {https://www.osapublishing.org/ao/abstract.cfm?uri=ao-48-33-6541}
,doi = {10.1364/AO.48.006541}
}
|
A study of oleic acid and 2,4-DHB acid aerosols using an IR-VUV-ITMS: insights into the strengths and weaknesses of the technique,
Hanna SJ, Campuzano-Jost P, Simpson EA, Burak I, Blades MW, Hepburn JW and Bertram AK,
Physical Chemistry Chemical Physics
11
(36)
, 7963-7975
(2009),
The Royal Society of Chemistry.
|
| Abstract: An investigation of oleic acid and 2,4-dihydroxybenzoic (DHB) acid aerosols was carried out using an aerosol mass spectrometer with pulsed lasers for vaporization and ionization and an ion trap for mass analysis. The extent of ion fragmentation was studied as a function of both vaporization energy and ionization wavelength. Low CO2 laser energies in the vaporization stage and near-threshold single photon ionization resulted in the least fragmented mass spectra. For DHB, only the molecular ion was observed, but for oleic acid fragmentation could not be eliminated. Tandem MS of the main fragment peak from oleic acid was carried out and provided a tool for compound identification. Photoionization efficiency curves were also collected for both DHB and oleic acid and the appearance energies of both parent and fragment ions were measured. Evidence for fragmentation occurring post-ionization is given by the similar appearance energies for both the parent and fragment ions. The results from this study were compared with those from similar experiments undertaken with time-of-flight (TOF) mass analyzers. The degree of fragmentation in the ion trap was considerably higher than that seen with TOF systems, particularly for oleic acid. This was attributed to the long storage interval in the ion trap which allows time for metastable ions to decay. Differences in the degree of fragmentation between the ion trap and TOF studies also provided further evidence for fragmentation occurring post-ionization. For 2,4-dihydroxybenzoic acid, the long delay prior to mass analysis also allowed time for reactions with background gases, in this case water, to occur. |
BibTeX:
@article
{Hanna2009a,
title = {A study of oleic acid and 2,4-DHB acid aerosols using an IR-VUV-ITMS: insights into the strengths and weaknesses of the technique}
,author = {Hanna, Sarah J. and Campuzano-Jost, Pedro and Simpson, Emily A. and Burak, Itamar and Blades, Michael W. and Hepburn, John W. and Bertram, Allan K.}
,journal = {Physical Chemistry Chemical Physics}
,publisher = {The Royal Society of Chemistry}
,year = {2009}
,volume = {11}
,number = {36}
,pages = {7963--7975}
,url = {https://pubs.rsc.org/en/content/articlelanding/2009/cp/b904748d}
,doi = {10.1039/B904748D}
}
|
A laser desorption–electron impact ionization ion trap mass spectrometer for real-time analysis of single atmospheric particles,
Simpson EA, Campuzano-Jost P, Hanna SJ, Robb DB, Hepburn JH, Blades MW and Bertram AK,
International Journal of Mass Spectrometry
281
(3)
, 140-149
(2009),
|
| Abstract: A novel aerosol ion trap mass spectrometer combining pulsed IR laser desorption with electron impact (EI) ionization for single particle studies is described. The strengths of this instrument include a two-step desorption and ionization process to minimize matrix effects; electron impact ionization, a universal and well-characterized ionization technique; vaporization and ionization inside the ion trap to improve sensitivity; and an ion trap mass spectrometer for MSn experiments. The instrument has been used for mass spectral identification of laboratory generated pure aerosols in the 600nm–1.1µm geometric diameter range of a variety of aromatic and aliphatic compounds, as well as for tandem mass spectrometry studies (up to MS3) of single caffeine particles. We investigate the effect of various operational parameters on the mass spectrum and fragmentation patterns. The single particle detection limit of the instrument was found to be a 325nm geometric diameter particle (8.7×107 molecules or 22fg) for 2,4-dihydroxybenzoic acid. Lower single particle detection limits are predicted to be attainable by modifying the EI pulse. The use of laser desorption-electron impact (LD-EI) in an ion trap is a promising technique for determining the size and chemical composition of single aerosol particles in real time. |
BibTeX:
@article
{Simpson2009,
title = {A laser desorption–electron impact ionization ion trap mass spectrometer for real-time analysis of single atmospheric particles}
,author = {Simpson, Emily A. and Campuzano-Jost, Pedro and Hanna, Sarah J. and Robb, D. B. and Hepburn, John H. and Blades, Michael W. and Bertram, Allan K.}
,journal = {International Journal of Mass Spectrometry}
,year = {2009}
,volume = {281}
,number = {3}
,pages = {140--149}
,url = {http://www.sciencedirect.com/science/article/pii/S1387380609000335}
,doi = {10.1016/j.ijms.2009.01.013}
}
|
Patterned Superhydrophobic Metallic Surfaces,
Kietzig A-M, Hatzikiriakos SG and Englezos P,
Langmuir
25
(8)
, 4821-4827
(2009),
American Chemical Society.
|
| Abstract: This work shows that after creating certain dual scale roughness structures by femtosecond laser irradiation different metal alloys initially show superhydrophilic behavior with complete wetting of the structured surface. However, over time, these surfaces become nearly superhydrophobic with contact angles in the vicinity of 150° and superhydrophobic with contact angles above 150°. The contact angle hysteresis was found to lie between 2 and 6°. The change in wetting behavior correlates with the amount of carbon on the structured surface. The explanation for the time dependency of the surface wettability lies in the combined effect of surface morphology and surface chemistry. |
BibTeX:
@article
{Kietzig2009,
title = {Patterned Superhydrophobic Metallic Surfaces}
,author = {Kietzig, Anne-Marie and Hatzikiriakos, Savvas G. and Englezos, Peter}
,journal = {Langmuir}
,publisher = {American Chemical Society}
,year = {2009}
,volume = {25}
,number = {8}
,pages = {4821--4827}
,url = {https://doi.org/10.1021/la8037582}
,doi = {10.1021/la8037582}
}
|
Complete transfer of populations from a single state to a preselected superposition of states using piecewise adiabatic passage: Theory,
Shapiro EA, Milner V and Shapiro M,
Physical Review A
79
(2)
, 023422
(2009),
American Physical Society.
|
| Abstract: We develop a method for executing robust and selective transfer of populations between a single level and preselected superpositions of energy eigenstates. Viewed in the frequency domain, our method amounts to executing a series of simultaneous adiabatic passages into each component of the target superposition state. Viewed in the time domain, the method works by accumulating the wave function of the target wave packet as it revisits the transition region, in what amounts to an extension of the piecewise adiabatic passage technique [E. A. Shapiro et al., Phys. Rev. Lett. 99, 033002 (2007)] to the multistate regime. The viability of the method is verified by performing numerical tests for the Na2 molecule. |
BibTeX:
@article
{Shapiro2009,
title = {Complete transfer of populations from a single state to a preselected superposition of states using piecewise adiabatic passage: Theory}
,author = {Shapiro, Evgeny A. and Milner, Valery and Shapiro, Moshe}
,journal = {Physical Review A}
,publisher = {American Physical Society}
,year = {2009}
,volume = {79}
,number = {2}
,pages = {023422}
,url = {https://link.aps.org/doi/10.1103/PhysRevA.79.023422}
,doi = {10.1103/PhysRevA.79.023422}
}
|
Effects of Fuel Composition on High-Pressure Non-Premixed Natural Gas Combustion,
McTaggart-Cowan GP, Wu N, Jin B, Rogak SN, Davy MH and Bushe WK,
Combustion Science and Technology
181
(3)
, 397-416
(2009),
Taylor & Francis.
|
| Abstract: The effects of adding ethane or nitrogen on the ignition and combustion of a non-premixed high-pressure methane-air jet have been investigated using fundamental studies in a shock tube and advanced computational modeling. The results are then used to interpret the performance of a pilot-ignited natural gas engine fueled with similar fuels. The results show that the influence of the additives on the gaseous jet ignition process is relatively small, but that they have a greater effect on the research engine, where both fuels have similar influences on the spatial relationship between the gaseous jet and the pilot flame. |
BibTeX:
@article
{McTaggartCowan2009,
title = {Effects of Fuel Composition on High-Pressure Non-Premixed Natural Gas Combustion}
,author = {McTaggart-Cowan, G. P. and Wu, N. and Jin, B. and Rogak, Steven N. and Davy, M. H. and Bushe, W. K.}
,journal = {Combustion Science and Technology}
,publisher = {Taylor & Francis}
,year = {2009}
,volume = {181}
,number = {3}
,pages = {397--416}
,url = {https://doi.org/10.1080/00102200802612260}
,doi = {10.1080/00102200802612260}
}
|
Linker-Dependent Metal-Sensitized Photoswitching of Dithienylethenes,
Roberts MN, Nagle JK, Finden JG, Branda NR and Wolf MO,
Inorganic Chemistry
48
(1)
, 19-21
(2009),
American Chemical Society.
|
| Abstract: Intramolecular energy-transfer results in sensitized ring closing of a pendant dithienylethene from a platinum terpyridyl complex only when the two components are connected with a short p-conjugated linker. |
BibTeX:
@article
{Roberts2009a,
title = {Linker-Dependent Metal-Sensitized Photoswitching of Dithienylethenes}
,author = {Roberts, Matthew N. and Nagle, Jeffrey K. and Finden, Jeremy G. and Branda, Neil R. and Wolf, Michael O.}
,journal = {Inorganic Chemistry}
,publisher = {American Chemical Society}
,year = {2009}
,volume = {48}
,number = {1}
,pages = {19--21}
,url = {https://doi.org/10.1021/ic801619v}
,doi = {10.1021/ic801619v}
}
|
A new broadly tunable (7.4–10.2eV) laser based VUV light source and its first application to aerosol mass spectrometry,
Hanna SJ, Campuzano-Jost P, Simpson EA, Robb DB, Burak I, Blades MW, Hepburn JW and Bertram AK,
International Journal of Mass Spectrometry
279
(2)
, 134-146
(2009),
|
| Abstract: A laser based vacuum ultraviolet (VUV) light source using resonance enhanced four wave difference mixing in xenon gas was developed for near threshold ionization of organics in atmospheric aerosol particles. The source delivers high intensity pulses of VUV light (in the range of 1010 to 1013 photons/pulse depending on wavelength, 5ns FWHM) with a continuously tunable wavelength from 122nm (10.2eV) to 168nm (7.4eV). The setup allows for tight (textless1mm2) and precise focusing (µrad pointing angle adjustability), attributes required for single particle detection. The generated VUV is separated from the pump wavelengths by a custom monochromator which ensures high spectral purity and minimizes absorptive losses. The performance of the source was characterized using organic molecules in the gas phase and optimal working conditions are reported. In the gas phase measurements, photoionization efficiency (PIE) curves were collected for seven different organic species with ionization energies spanning the full wavelength range of the VUV source. The measured appearance energies are very close to the literature values of the ionization energies for all seven species. The effectiveness of the source for single particle studies was demonstrated by analysis of individual caffeine aerosols vaporized by a pulsed CO2 laser in an ion trap mass spectrometer. Mass spectra from single particles down to 300nm in diameter were collected. Excellent signal to noise characteristics for these small particles give a caffeine detection limit of 8×105 molecules which is equivalent to a single 75nm aerosol, or approximately 1.5% of a 300nm particle. The appearance energy of caffeine originating from the aerosol was also measured and found to be 7.91±0.05eV, in good agreement with literature values. |
BibTeX:
@article
{Hanna2009,
title = {A new broadly tunable (7.4–10.2eV) laser based VUV light source and its first application to aerosol mass spectrometry}
,author = {Hanna, Sarah J. and Campuzano-Jost, Pedro and Simpson, Emily A. and Robb, D. B. and Burak, Itamar and Blades, Michael W. and Hepburn, John W. and Bertram, Aallan K.}
,journal = {International Journal of Mass Spectrometry}
,year = {2009}
,volume = {279}
,number = {2}
,pages = {134--146}
,url = {http://www.sciencedirect.com/science/article/pii/S1387380608004296}
,doi = {10.1016/j.ijms.2008.10.024}
}
|
Nonlinear Optical Properties of Schiff-Base-Containing Conductive Polymer Films Electro-deposited in Microgravity,
Pietrangelo A, Sih BC, Boden BN, Wang Z, Li Q, Chou KC, MacLachlan MJ and Wolf MO,
Advanced Materials
20
(12)
, 2280-2284
(2008),
|
| Abstract: Organic–inorganic hybrid films prepared from copper(II)-containing Schiff base complexes bearing long alkoxy chains grown under microgravity conditions show enhanced third-order NLO susceptibilities relative to films grown at 1 g. |
BibTeX:
@article
{Pietrangelo2008,
title = {Nonlinear Optical Properties of Schiff-Base-Containing Conductive Polymer Films Electro-deposited in Microgravity}
,author = {Pietrangelo, Agostino and Sih, Bryan C. and Boden, Britta N. and Wang, Zhenwei and Li, Qifeng and Chou, Keng C. and MacLachlan, Mark J. and Wolf, Michael O.}
,journal = {Advanced Materials}
,year = {2008}
,volume = {20}
,number = {12}
,pages = {2280--2284}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.200702582}
,doi = {10.1002/adma.200702582}
}
|
Reversible and Amplified Fluorescence Quenching of a Photochromic Polythiophene,
Finden J, Kunz TK, Branda NR and Wolf MO,
Advanced Materials
20
(10)
, 1998-2002
(2008),
|
| Abstract: Amplification of fluorescence quenching of a polythiophene is optically triggered by converting pendant dithienylethene (DTE) photoswitches to their ring- closed isomers using UV light. The effect can be reversed with visible light, which regenerates the original DTE isomer. Amplification attributed to the high mobility of electronic excited states in conjugated polymers, which facilitates energy transfer to a ring-closed DTE. |
BibTeX:
@article
{Finden2008,
title = {Reversible and Amplified Fluorescence Quenching of a Photochromic Polythiophene}
,author = {Finden, Jeremy and Kunz, Tamara K. and Branda, Neil R. and Wolf, Michael O.}
,journal = {Advanced Materials}
,year = {2008}
,volume = {20}
,number = {10}
,pages = {1998--2002}
,url = {https://onlinelibrary.wiley.com/doi/abs/10.1002/adma.200702455}
,doi = {10.1002/adma.200702455}
}
|
Background-free coherent Raman spectroscopy by detecting the spectral phase of molecular vibrations,
Xu XG, Konorov SO, Hepburn JW and Milner V,
Optics Letters
33
(11)
, 1177-1179
(2008),
Optical Society of America.
|
| Abstract: We propose and demonstrate a new approach to subtracting high nonresonant background in coherent anti-Stokes Raman scattering spectroscopy. The method is based on the retrieval of the spectral phase of molecular vibrations using the technique of frequency-resolved optical gating of Raman scattering. In the presence of high nonresonant background the retrieved phase corresponds directly to the background-free spectrum of the coherent Raman response. |
BibTeX:
@article
{Xu2008,
title = {Background-free coherent Raman spectroscopy by detecting the spectral phase of molecular vibrations}
,author = {Xu, Xiaoji G. and Konorov, Stanislav O. and Hepburn, John W. and Milner, Valery}
,journal = {Optics Letters}
,publisher = {Optical Society of America}
,year = {2008}
,volume = {33}
,number = {11}
,pages = {1177--1179}
,url = {https://www.osapublishing.org/ol/abstract.cfm?uri=ol-33-11-1177}
,doi = {10.1364/OL.33.001177}
}
|
Population Transfer between Two Quantum States by Piecewise Chirping of Femtosecond Pulses: Theory and Experiment,
Zhdanovich S, Shapiro EA, Shapiro M, Hepburn JW and Milner V,
Physical Review Letters
100
(10)
, 103004
(2008),
American Physical Society.
|
| Abstract: We propose and experimentally demonstrate the method of population transfer by piecewise adiabatic passage between two quantum states. Coherent excitation of a two-level system with a train of ultrashort laser pulses is shown to reproduce the effect of an adiabatic passage, conventionally achieved with a single frequency-chirped pulse. By properly adjusting the amplitudes and phases of the pulses in the excitation pulse train, we achieve complete and robust population transfer to the target state. The piecewise nature of the process suggests a possibility for the selective population transfer in complex quantum systems. |
BibTeX:
@article
{Zhdanovich2008,
title = {Population Transfer between Two Quantum States by Piecewise Chirping of Femtosecond Pulses: Theory and Experiment}
,author = {Zhdanovich, Sergey and Shapiro, Evengy A. and Shapiro, M. and Hepburn, John W. and Milner, Valery}
,journal = {Physical Review Letters}
,publisher = {American Physical Society}
,year = {2008}
,volume = {100}
,number = {10}
,pages = {103004}
,url = {https://link.aps.org/doi/10.1103/PhysRevLett.100.103004}
,doi = {10.1103/PhysRevLett.100.103004}
}
|
Noise autocorrelation spectroscopy with coherent Raman scattering,
Xu XG, Konorov SO, Hepburn JW and Milner V,
Nature Physics
4
(2)
, 125-129
(2008),
Nature Publishing Group.
|
| Abstract: Coherent anti-Stokes Raman scattering (CARS) with femtosecond laser pulses has become a widespread method in nonlinear optical spectroscopy and microscopy1,2. As a third-order nonlinear process, femtosecond CARS exhibits high efficiency at low average laser power. High sensitivity to molecular structure enables detection of small quantities of complex molecules3,4 and non-invasive biological imaging5. Temporal and spectral resolution of CARS is typically limited by the duration of the excitation pulses and their frequency bandwidth, respectively. Broadband femtosecond pulses are advantageous for time-resolved CARS spectroscopy6,7, but offer poor spectral resolution. The latter can be improved by invoking optical8,9 or quantum10,11 interference at the expense of increasing complexity of instrumentation and susceptibility to noise. Here, we present a new approach to coherent Raman spectroscopy in which high resolution is achieved by means of deliberately introduced noise. The proposed method combines the efficiency of a coherent process with the robustness of incoherent light. It does require averaging over different noise realizations, but no temporal scanning or spectral pulse shaping as commonly used by frequency-resolved spectroscopic methods with ultrashort pulses. |
BibTeX:
@article
{Xu2008a,
title = {Noise autocorrelation spectroscopy with coherent Raman scattering}
,author = {Xu, Xiaoji G. and Konorov, Stanislav O. and Hepburn, John W. and Milner, Valery}
,journal = {Nature Physics}
,publisher = {Nature Publishing Group}
,year = {2008}
,volume = {4}
,number = {2}
,pages = {125--129}
,url = {https://www.nature.com/articles/nphys809}
,doi = {10.1038/nphys809}
}
|
Complete characterization of molecular vibration using frequency resolved gating,
Xu XG, Konorov SO, Zhdanovich S, Hepburn JW and Milner V,
J. Chem. Phys.
126
, 091102
(2007),
American Institute of Physics.
|
| Abstract: The authors propose a new approach to vibration spectroscopy based on the coherent anti-Stokes Raman scattering of broadband ultrashort laser pulses. The proposed method reveals both the amplitude and the phase of molecular vibrations by utilizing the cross-correlation frequency resolved optical gating (XFROG) technique. The spectrum of the anti-Stokes pulse is measured as a function of the time delay between the laser-induced molecular vibrations and a well characterized broadband femtosecond probe pulse. The iterative XFROG algorithm provides a simultaneous complete characterization of molecular vibrations both in frequency and time domains with high resolution. They demonstrate experimentally the feasibility of the proposed method and show one of its potential applications in disentangling the time behavior of a mixture of vibrationally excited molecules. The technique of femtosecond pulse shaping is used for further improvement of accuracy and stability against noise. |
BibTeX:
@article
{Xu2007,
title = {Complete characterization of molecular vibration using frequency resolved gating}
,author = {Xu, Xiaoji G. and Konorov, Stanislav O. and Zhdanovich, Sergey and Hepburn, John W. and Milner, Valery}
,journal = {J. Chem. Phys.}
,publisher = {American Institute of Physics}
,year = {2007}
,volume = {126}
,pages = {091102}
}
|
Background-Free Coherent Anti-Stokes Raman Scattering of Gas- and Liquid-Phase Samples in a Mesoporous Silica Aerogel Host,
Konorov SO, Turner RFB and Blades MW,
Applied Spectroscopy
61
(5)
, 486-489
(2007),
|
| Abstract: Efficient time-resolved coherent anti-Stokes Raman scattering (CARS) of atmospheric nitrogen and ethanol trapped in a nanoporous silica aerogel matrix is demonstrated. Silica aerogel hosts are attractive for analytical CARS spectroscopy due to their high porosity/low density, low refractive index, and low scattering cross-section. Differences between the resonant and nonresonant parts of the nonlinear optical susceptibilities lead to much longer relaxation times for analytes compared to the matrix. Time-resolved CARS can then be used to obtain a nearly background-free measurement at characteristic vibrations of the analyte. These results demonstrate the potential of this approach for rapid, sensitive, background-free analyses of analytes entrapped in the aerogel pores, which may be advantageous for some environmental, chemical, and biological sensing applications. |
BibTeX:
@article
{Konorov2007b,
title = {Background-Free Coherent Anti-Stokes Raman Scattering of Gas- and Liquid-Phase Samples in a Mesoporous Silica Aerogel Host}
,author = {Stanislav O. Konorov and Robin F. B. Turner and Michael W. Blades}
,journal = {Applied Spectroscopy}
,year = {2007}
,volume = {61}
,number = {5}
,pages = {486-489}
,note = {PMID: 17555617}
,url = {https://doi.org/10.1366/000370207780807803}
,doi = {10.1366/000370207780807803}
}
|
In Situ Analysis of Living Embryonic Stem Cells by Coherent Anti-Stokes Raman Microscopy,
Konorov SO, Glover CH, Piret JM, Bryan J, Schulze HG, Blades MW and Turner RFB,
Analytical Chemistry
79
(18)
, 7221-7225
(2007),
American Chemical Society.
|
| Abstract: Embryonic stem cells (ESC), derived from preimplantation embryos, are defined by their ability to both self-renew and differentiate into all of the cells and tissues of a mature animal. Efforts to develop methods for in vitro culture of ESC for research or eventual therapeutic applications are hampered by the lack of rapid, nondestructive assays for distinguishing ESC from other (differentiated) cells within a growing culture. Coherent anti-Stokes Raman scattering (CARS) microscopy is shown here to be a sensitive and nondestructive method for identifying mouse ESC based on selective observation of specific molecular vibrations believed to be spectroscopic markers indicating the differentiated vs undifferentiated states of such cells. The nonlinear nature of CARS also permits imaging with subcellular resolution, potentially offering a means by which chemical changes accompanying the early stages of differentiation may be associated with certain intracellular compartments (e.g., nucleus, cytoplasm, membranes). A novel exposure/collection configuration is described, which yields high collection efficiency and low interference from nonresonant background components. |
BibTeX:
@article
{Konorov2007,
title = {In Situ Analysis of Living Embryonic Stem Cells by Coherent Anti-Stokes Raman Microscopy}
,author = {Konorov, Stanislav O. and Glover, Clive H. and Piret, James M. and Bryan, Jennifer and Schulze, H. Georg and Blades, Michael W. and Turner, Robin F. B.}
,journal = {Analytical Chemistry}
,publisher = {American Chemical Society}
,year = {2007}
,volume = {79}
,number = {18}
,pages = {7221--7225}
,url = {https://doi.org/10.1021/ac070544k}
,doi = {10.1021/ac070544k}
}
|
Piecewise Adiabatic Passage with a Series of Femtosecond Pulses,
Shapiro EA, Milner V, Menzel-Jones C and Shapiro M,
Physical Review Letters
99
(3)
, 033002
(2007),
American Physical Society.
|
| Abstract: We develop a method of executing complete population transfers between quantum states in a piecewise manner using a series of femtosecond laser pulses. The method can be applied to a large class of problems as it benefits from the high peak powers and large spectral bandwidths afforded by femtosecond pulses. The degree of population transfer is robust to a wide variation in the absolute and relative intensities, durations, and time ordering of the pulses. The method is studied in detail for atomic sodium where piecewise adiabatic population transfer, as well as the induction of Ramsey-type interferences, is demonstrated. |
BibTeX:
@article
{Shapiro2007,
title = {Piecewise Adiabatic Passage with a Series of Femtosecond Pulses}
,author = {Shapiro, Evengy A. and Milner, Valery and Menzel-Jones, C. and Shapiro, M.}
,journal = {Physical Review Letters}
,publisher = {American Physical Society}
,year = {2007}
,volume = {99}
,number = {3}
,pages = {033002}
,url = {https://link.aps.org/doi/10.1103/PhysRevLett.99.033002}
,doi = {10.1103/PhysRevLett.99.033002}
}
|
Pulse optimization for Raman spectroscopy with cross-correlation frequency resolved optical gating,
Konorov SO, Xu XG, Turner RFB, Blades MW, Hepburn JW and Milner V,
Optics Express
15
(12)
, 7564-7571
(2007),
Optical Society of America.
|
| Abstract: We propose to employ the technique of femtosecond pulse shaping for improving the performance of the recently suggested method of complete characterization of molecular vibrations, in which both the amplitude and phase of the laser induced vibrational coherence are detected with high resolution. The amplitude-phase information is retrieved from the cross-correlation frequency resolved optical gating of Raman modes. By creating rich interference pattern in the measured two-dimensional spectrogram of coherent anti-Stokes Raman scattering we enhance the accuracy of the retrieved spectral and temporal response and increase the robustness of the method against noise. |
BibTeX:
@article
{Konorov2007a,
title = {Pulse optimization for Raman spectroscopy with cross-correlation frequency resolved optical gating}
,author = {Konorov, Stanislav O. and Xu, Xiaoji G. and Turner, Robin F. B. and Blades, Michael W. and Hepburn, John W. and Milner, Valery}
,journal = {Optics Express}
,publisher = {Optical Society of America}
,year = {2007}
,volume = {15}
,number = {12}
,pages = {7564--7571}
,url = {https://www.osapublishing.org/oe/abstract.cfm?uri=oe-15-12-7564}
,doi = {10.1364/OE.15.007564}
}
|
Third-Order Nonlinear Optical Response from Polythiophene-Based Thin Films,
Mattu J, Johansson T and Leach GW,
The Journal of Physical Chemistry C
111
(18)
, 6868-6874
(2007),
American Chemical Society.
|
| Abstract: Optical quality films of the amphiphillic, regioregular polymer PTHPUDT were fabricated via the Langmuir-Blodgett technique, and their third-order nonlinear optical response was investigated using z-scan methods. Analysis of the resulting z-scan data yielded values of = -1.2 × 10-9 esu and = -3.5 × 10-11 esu, consistent with previous studies on polythiophene-based polymers systems. However, even with relatively low intensities incident on pristine PTHPUDT polymer films, the required power to achieve a nonlinear response in the film is sufficient to produce photoinduced changes in the original polymer. These photoinduced changes are consistent with the onset of photooxidation, photobleaching, and chain scission processes. At higher incident intensities, prolonged exposure of the film results in the removal or partial removal of the polymer from the irradiated region. This leads to linear optical effects that manifest themselves as z-scan traces that show pronounced asymmetry and intensity-independent peak-to-valley transmittance. Although our observations pertain specifically to PTHPUDT, our results may extend to the broader class of polythiophene-based materials more generally. These observations put into question whether the nonlinear optical susceptibility values of polythiophene-based materials currently being reported in the literature result from pristine polymers or from their photoconverted products. |
BibTeX:
@article
{Mattu2007,
title = {Third-Order Nonlinear Optical Response from Polythiophene-Based Thin Films}
,author = {Mattu, J. and Johansson, T. and Leach, Gary. W.}
,journal = {The Journal of Physical Chemistry C}
,publisher = {American Chemical Society}
,year = {2007}
,volume = {111}
,number = {18}
,pages = {6868--6874}
,url = {https://doi.org/10.1021/jp0685434}
,doi = {10.1021/jp0685434}
}
|
Optical Second-Harmonic Generation Study of Exfoliated MoS2-Malachite Green Inclusion Materials,
Cetnarowski G and Leach GW,
Langmuir
22
(21)
, 8995-9001
(2006),
American Chemical Society.
|
| Abstract: We have examined the properties of exfoliated and restacked MoS2-malachite green (MG) inclusion compounds to provide insight into the MG-MoS2 interactions that characterize these materials. The results of X-ray diffraction experiments indicate that MG included into the restacked structure adopts a flat orientation approximately parallel to the MoS2 sheets. Second-harmonic generation experiments conducted on the exfoliated and restacked materials provide information regarding the averaged orientation of the MG. At low MG coverage, our results support the X-ray diffraction findings, and yield large averaged orientation angles, consistent with a flat orientation of MG between the MoS2 layers. However, as the MG coverage is increased, the SHG results indicate averaged MG orientations that are much more upright, consistent with the expulsion of excess MG from the layers to the outside of the restacked crystallites. Together with X-ray diffraction and adsorption isotherm data, our SHG results provide a model for the exfoliation, adsorption, and subsequent restacking of these MG-based inclusion materials and demonstrate the utility of nonlinear optical techniques as probes of these interesting layered structures. |
BibTeX:
@article
{Cetnarowski2006,
title = {Optical Second-Harmonic Generation Study of Exfoliated MoS2-Malachite Green Inclusion Materials}
,author = {Cetnarowski, Greg and Leach, Gary W.}
,journal = {Langmuir}
,publisher = {American Chemical Society}
,year = {2006}
,volume = {22}
,number = {21}
,pages = {8995--9001}
,url = {https://doi.org/10.1021/la060461j}
,doi = {10.1021/la060461j}
}
|
Sum Frequency Generation Study of Langmuir Blodgett Film Architecture,
Johansson T and Leach GW,
The Journal of Physical Chemistry B
110
(33)
, 16567-16574
(2006),
American Chemical Society.
|
| Abstract: We present sum frequency generation vibrational spectroscopy data on monolayer films of pure stearonitrile and mixed films of stearonitrile and ferric stearate deposited by the Langmuir Blodgett technique. Films ranging in composition from pure stearonitrile to 65% stearonitrile/35% ferric stearate deposit in a head-to-tail, Z-type architecture while films of composition textless65% stearonitrile deposit in a head-to-head, tail-to-tail, Y-type structure. The vibrational spectra of the monolayer films corresponding to these two different architectures show distinct and characteristic features in their CH stretching regions. Spectral analysis indicates little difference in the modes associated with the terminal methyl groups but large differences in the methylene CH2 vibrational modes. These spectral differences are consistent with alkyl chains that possess uncompensated methylene oscillator strength arising from portions of the chain that are bent. This behavior is consistent with the energetics expected from a close-packed monolayer of stearonitrile molecules whose CN headgroups possess sizable dipole moments and are expected to adopt a large center-to-center angle to minimize electrostatic, dipole-dipole repulsive interactions. |
BibTeX:
@article
{Johansson2006,
title = {Sum Frequency Generation Study of Langmuir Blodgett Film Architecture}
,author = {Johansson, T. and Leach, Gary. W.}
,journal = {The Journal of Physical Chemistry B}
,publisher = {American Chemical Society}
,year = {2006}
,volume = {110}
,number = {33}
,pages = {16567--16574}
,url = {https://doi.org/10.1021/jp060804m}
,doi = {10.1021/jp060804m}
}
|