A5058767195- Spectroscopy and Quantum Chemical Studies
- Photosynthetic Processes and Mechanisms
- Photoreceptor and optogenetics research
- Lipid Membrane Structure and Behavior
- Luminescence and Fluorescent Materials
- Porphyrin and Phthalocyanine Chemistry
- Conducting polymers and applications
- Molecular Junctions and Nanostructures
- Organic Electronics and Photovoltaics
- Photochemistry and Electron Transfer Studies
- Force Microscopy Techniques and Applications
- Nanocluster Synthesis and Applications
- Metal complexes synthesis and properties
- Carbon Nanotubes in Composites
- Magnetism in coordination complexes
- Mechanical and Optical Resonators
- Gold and Silver Nanoparticles Synthesis and Applications
- 3D Printing in Biomedical Research
- Advanced biosensing and bioanalysis techniques
- Algal biology and biofuel production
- Microfluidic and Bio-sensing Technologies
- Analytical Chemistry and Sensors
- Lanthanide and Transition Metal Complexes
- Electrochemical Analysis and Applications
- Innovative Microfluidic and Catalytic Techniques Innovation
University of New Mexico
2014-2024
Center for Integrated Nanotechnologies
2007-2012
Los Alamos National Laboratory
2003-2012
University of Alabama
2008-2010
Santa Fe Institute
2009-2010
University of Groningen
2009
Carnegie Mellon University
2009
Brookhaven National Laboratory
2009
National Taiwan University
2009
University of California, Davis
2003-2008
We report the experimental observation of intrinsic dynamically localized vibrational states in crystals highly nonlinear halide-bridged mixed-valence transition metal complex ${[\mathrm{Pt}(\mathrm{en}{)}_{2}][\mathrm{Pt}(\mathrm{en}{)}_{2}{\mathrm{Cl}}_{2}]({\mathrm{ClO}}_{4}{)}_{4}}$, where $\mathrm{en}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}\mathrm{ethylenediamine}$. These are identified by distinctive structure and strong redshifts they impose upon overtone resonance Raman...
Resonance Raman spectroscopy is a powerful technique for probing the vibrations of particular chromophores in multicomponent systems. By tuning wavelength excitation laser into resonance with an electronic absorption band only one molecular species, vibrational scattering from this species can be selectively enhanced. Thus, provide structural information solution or biological within their functionally active protein environment. However, since very nature experiment requires that light...
The B800-to-B850 energy transfer time in the purified B800-850 light-harvesting complex of Rhodobacter sphaeroides 2.4.1 is determined to be 0.7 ps at room temperature. electronic state dynamics principal carotenoid this species, spheroidene, are examined, both vivo and vitro, by direct femtosecond time-resolved experiments fluorescence emission yield studies. Evidence presented which suggests that carotenoid-to-bacteriochlorophyll may occur directly from initially excited S2 state, as well...
We report the discovery of a DNA sequence that templates highly stable fluorescent silver nanocluster. In contrast to other templated nanoclusters have relatively short shelf-life, species in this new retains significant fluorescence for at least year. Moreover, nanocluster possesses low cellular toxicity and enhanced thermal, oxidative, chemical stability.
Excited-state energy migration among a collection of pigments forms the basis for natural light-harvesting processes and synthetic molecular photonic devices. The rational design efficient energy-transfer devices requires ability to analyze expected performance characteristics target architectures comprised various pigments. Toward that goal, we present general tool modeling kinetics in weakly coupled multipigment arrays. A matrix-formulated eigenvalue/eigenvector approach has been...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSterically hindered aryloxide-substituted alkylaluminum compoundsAndrew P. Shreve, Rolf. Mulhaupt, William. Fultz, Joseph. Calabrese, Wayne. Robbins, and Steven D. IttelCite this: Organometallics 1988, 7, 2, 409–416Publication Date (Print):February 1, 1988Publication History Published online1 May 2002Published inissue 1 February 1988https://pubs.acs.org/doi/10.1021/om00092a026https://doi.org/10.1021/om00092a026research-articleACS...
Biological molecular imaging and sensing requires fluorophores that are not only stable bright, but also small enough to allow the unencumbered observation of movement proteins. Toward this goal, we have studied formation fluorescent metallic gold nanoclusters stabilized by molecule ligands. The morpholine piperazine backbones Good's buffers were used template clusters, through a process etching nanoparticles first formed in reaction. clusters found be subnanometer sized, with nanosecond...
DNA-templated silver nanoclusters are promising biological fluorescence probes due to their useful properties, including tunability of emission wavelength through DNA template sequence variations. Ag K-edge EXAFS analysis has been used obtain insight into nanocluster bonding, size, and structural correlations fluorescence. The results indicate the presence small (<30 atoms) containing Ag–Ag bonds Ag–N/O ligations DNA. leads differences in silver–DNA ligation as well size. support a model...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNear-Infrared Resonance Raman Spectroscopy of the Special Pair and Accessory Bacteriochlorophylls in Photosynthetic Reaction CentersNerine J. Cherepy, Andrew P. Shreve, Laura Moore, Stefan Franzen, Steven G. Boxer, Richard A. MathiesCite this: Phys. Chem. 1994, 98, 23, 6023–6029Publication Date (Print):June 1, 1994Publication History Published online1 May 2002Published inissue 1 June...
We report femtosecond transient absorption studies of energy transfer dynamics in the B800-850 light-harvesting complex (LHC) Rhodobacter sphaeroides 2.4.1. For complexes solubilized lauryldimethylamine-N-oxide (LDAO), carotenoid to bacteriochlorophyll (Bchl) B800 and Bchl B850 times are 0.34 0.20 ps, respectively. The time is 2.5 ps. treated with lithium dodecyl sulfate (LDS), a less than or equal 0.2 ps seen, portion total population decoupled from Bchl. In both LDAO-solubilized...
The effects of aggregate formation on the photophysical properties oligomers MEH-PPV were studied in bulk solution to better understand aggregation emission polymer. Nanoaggregates from 3 17 repeat units length formed using a solvent reprecipitation method. spectra are not readily modeled classical dipole−dipole coupling picture interchain interactions. A strong dependence photophysics oligomer chain is also observed. Short-chain produce nanoaggregates with absorption and essentially...
Metal nanoclusters have interesting steady state fluorescence emission, two-photon excited emission and ultrafast dynamics. A new subclass of fluorescent silver (Ag NCs) are NanoCluster Beacons. Beacons consist a weakly emissive Ag NC templated on single stranded DNA ("Ag ssDNA") that becomes highly when enhancer sequence is brought in proximity to the by base pairing dsDNA"). Steady was observed at 540 nm for both ssDNA dsDNA; 650 dsDNA. The 550 eight times weaker than nm. Fluorescence...
Employing concepts from physics, chemistry and bioengineering, 'learning-by-building' approaches are becoming increasingly popular in the life sciences, especially with researchers who attempting to engineer cellular scratch. The SynCell2020/21 conference brought together different disciplines highlight progress this field, including areas where synthetic cells having socioeconomic technological impact. Conference participants also identified challenges involved designing, manipulating...
We have studied the spreading of phospholipid vesicles on photochemically patterned n-octadecylsiloxane monolayers using epifluorescence and imaging ellipsometry measurements. Self-assembled n-octadecylsiloxanes were short-wavelength ultraviolet radiation a photomask to produce periodic arrays hydrophilic domains separated from hydrophobic surroundings. Exposing these surfaces solution small unilamellar phospholipids their mixtures resulted in complex lipid layer morphology epitaxially...
Rapid-flow resonance Raman vibrational spectra of bacterial photosynthetic reaction centers from the R-26 mutant Rhodobacter sphaeroides have been obtained by using excitation wavelengths (810-910 nm) resonant with lowest energy, photochemically active electronic absorption. The technique shifted difference spectroscopy is used to identify genuine scattering bands in presence a large fluorescence background. comparison untreated and treated oxidant K3Fe(CN)6 demonstrates that enhancement...
Raman excitation profiles are obtained and compared for carbon nanotube radial breathing mode (RBM) fundamental overtone vibrations 5 specific chiralities. Fitting of the data is performed using transform theory. The Huang-Rhys factors from modeling directly related to magnitude RBM exciton-phonon coupling element, which shown be in a weak limit. values strengths possible role revealed non-Condon effects agreement with quantum-chemical modeling.
The Condon approximation is widely applied in molecular and condensed matter spectroscopy states that electronic transition dipoles are independent of nuclear positions. This related to the Franck–Condon principle, which its simplest form holds transitions instantaneous on time scale motion. leads a long-held assumption Raman carbon nanotubes: intensities arising from resonance with incident scattered photons equal. Direct testing this has not been possible due lack homogeneous populations...
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal Effects in Resonance Raman Scattering: Analysis of the Intensities Rhodopsin and Time-Resolved Scattering BacteriorhodopsinAndrew P. Shreve Richard A. MathiesCite this: J. Phys. Chem. 1995, 99, 19, 7285–7299Publication Date (Print):May 1, 1995Publication History Published online1 May 2002Published inissue 1 1995https://pubs.acs.org/doi/10.1021/j100019a012https://doi.org/10.1021/j100019a012research-articleACS PublicationsRequest reuse...
Lipid vesicles are used as the organizational structure of self-assembled light-harvesting systems. Following analysis 17 chromophores, six were selected for inclusion in vesicle-based antennas. The complementary absorption features chromophores span near-ultraviolet, visible, and near-infrared region. Although overall concentration pigments is low (∼1 μM quantitative spectroscopic studies) a cuvette, lipid-vesicle system affords high (≥10 mM) bilayer efficient energy flow from donor to...
A water-soluble porphyrin, meso-tetra(4-sulfonatophenyl)porphyrin (TSPP), has been associated with two different polycations, poly(diallyldimethylammonium chloride) (PDDA) and poly(ethyleneimine) (PEI), to investigate the effects of polymer binding upon TSPP structure excited-state dynamics both in solution ultrathin (∼10−30 Å) films deposited on glass slides by electrostatic assembly. Association porphyrin PEI intrinsically quenches singlet state TSPP, films, while quenching is observed...
Resonance Raman spectra and absolute scattering intensities of the Franck−Condon coupled vibrational modes accessory bacteriochlorophylls (B) in photosynthetic reaction center from Rb. sphaeroides have been obtained with excitation their 800 nm Qy absorption band. Although relative are unchanged when temperature is reduced 278 to 95 K, intensity found increase by a factor ∼4 at K. A self-consistent multimode vibronic model for excited-state properties B has developed that provides unique fit...
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