A5062707882- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Laser-Matter Interactions and Applications
- Spectroscopy and Laser Applications
- Photochemistry and Electron Transfer Studies
- Spectroscopy Techniques in Biomedical and Chemical Research
- Molecular spectroscopy and chirality
- Photoreceptor and optogenetics research
- Atmospheric Ozone and Climate
- X-ray Spectroscopy and Fluorescence Analysis
- Mass Spectrometry Techniques and Applications
- X-ray Diffraction in Crystallography
- Electron Spin Resonance Studies
- Quantum Dots Synthesis And Properties
- Electron and X-Ray Spectroscopy Techniques
- Metal-Catalyzed Oxygenation Mechanisms
- Electrochemical Analysis and Applications
- Photosynthetic Processes and Mechanisms
- Microbial Fuel Cells and Bioremediation
- Advanced biosensing and bioanalysis techniques
- Electrochemical sensors and biosensors
- Gold and Silver Nanoparticles Synthesis and Applications
- solar cell performance optimization
- Water Quality Monitoring and Analysis
- Advanced Fiber Laser Technologies
Northwestern University
2024
University of California, Berkeley
2020-2024
Lawrence Berkeley National Laboratory
2021-2023
University of Washington
2014-2022
University of Portland
2013-2015
Pacific Northwest National Laboratory
2013
Abstract The complex choreography of electronic, vibrational, and vibronic couplings used by photoexcited molecules to transfer energy efficiently is remarkable, but an unambiguous description the temporally evolving states governing these processes has proven experimentally elusive. We use multidimensional electronic-vibrational spectroscopy identify specific time-dependent excited state involving multiple electronic states, high-frequency vibrations, low-frequency vibrations which...
Two-Dimensional Electronic-Vibrational (2D EV) spectroscopy and Vibrational-Electronic VE) are new coherent four-wave mixing spectroscopies that utilize both electronically resonant vibrationally field-matter interactions to elucidate couplings between electronic vibrational degrees of freedom. A system Hamiltonian is developed here lay a foundation for interpreting the 2D EV VE signals arise from vibronically coupled molecular in condensed phase. consisting one anharmonic vibration two...
The development of coherent Fourier transform two-dimensional electronic-vibrational (2D EV) spectroscopy with acousto-optic pulse-shaper-generated near-UV pump pulses and an octave-spanning broadband mid-IR probe pulse is detailed. A 2D EV spectrum a silicon wafer demonstrates the full experimental capability this experiment, dissolved hexacyanoferrate establishes viability our experiment for studying condensed phase molecular ensembles.
This study uses polarization-selective two-dimensional electronic–vibrational (2D EV) spectroscopy to map intramolecular charge transfer in the well-known solar cell dye, [Ru(dcbpy)2(NCS)2]4– (N34–), dissolved water. A static snapshot of vibronic couplings present aqueous N34– is reported. At least three different initially excited singlet metal-to-ligand charge-transfer (MLCT) states are observed be coupled vibrational modes probed lowest energy triplet MLCT state, emphasizing role coupling...
Nonlinear wave mixing in solids with ultrafast x-rays can provide insight into complex electronic dynamics of materials. Here, tabletop-based attosecond noncollinear four-wave (FWM) spectroscopy using one extreme ultraviolet (XUV) pulse from high harmonic generation and two separately timed few-cycle near-infrared (NIR) pulses characterizes the ${\mathrm{Na}}^{+}$ ${L}_{2,3}$ edge core-excitons NaCl around 33.5 eV. An inhomogeneous distribution underlying well-known doublet absorption...
Developing interfacial probes of ligand-nanocluster interactions is crucial for understanding and tailoring the optoelectronic properties these emerging nanomaterials. Using transient IR spectroscopy, we demonstrate that ligand vibrational modes oleate-capped 1.3 nm InP nanoclusters report on photogenerated exciton. The exciton induces an intensity change in asymmetric carboxylate stretching mode by 57% while generating no appreciable shift frequency. Thus, observed difference signal...
Two-dimensional Electronic–Vibrational (2D EV) spectroscopy and two-dimensional Vibrational–Electronic VE) are among the newest additions to coherent multidimensional toolbox, they directly sensitive vibronic couplings. In this first of two papers, complete orientational response functions developed for a model system consisting coupled anharmonic oscillators electronic states in order simulate polarization-selective 2D EV VE spectra with arbitrary combinations linearly polarized electric...
Quantifying charge delocalization associated with short-lived photoexcited states of molecular complexes in solution remains experimentally challenging, requiring local element specific femtosecond experimental probes time-evolving electron transfer. In this study, we quantify the evolving valence hole distribution transfer state a prototypical mixed bimetallic iron-ruthenium complex, [(CN)5FeIICNRuIII(NH3)5]-, water by combining X-ray spectroscopy measurements time-dependent density...
A simple enzyme-free spectrophotometric detection of hydrogen peroxide is demonstrated based on its colorimetric reaction with oxygen deficient cerium oxide nanoparticles (CNPs). This sensitivity CNPs towards H2O2 increases significantly decreasing crystallite size due to an increase in the surface area as well concentration Ce3+ surface. The origin this was studied using DFT that suggests adsorption and molecules ceria creates new states electronic structure leading transitions absorbing...
Experimental demonstrations of polarization-selection two-dimensional Vibrational-Electronic (2D VE) and 2D Electronic-Vibrational EV) spectroscopies aim to map the magnitudes spatial orientations coupled electronic vibrational coordinates in complex systems. The realization that goal depends on our ability connect spectroscopic observables with molecular structural parameters. In this paper, we use a model Hamiltonian consisting two anharmonically modes ground excited states linear bilinear...
Attosecond four-wave mixing spectroscopy using an XUV pulse and two noncollinear near-infrared pulses is employed to measure Rydberg wavepacket dynamics resulting from extreme ultraviolet excitation of a 3s electron in atomic argon into series autoionizing 3s-1np states around 29 eV. The emitted signals individual exhibit oscillatory structure persist well beyond the expected lifetimes emitting states. These results reflect substantial contributions longer-lived four wave emission each...
Attosecond noncollinear four-wave-mixing spectroscopy with one attosecond extreme ultraviolet (XUV) pulse and two few-cycle near-infrared (NIR) pulses was used to measure the autoionization decay lifetimes of inner valence electronic excitations in neon atoms. After a 43--48-eV XUV photon excites $2s$ electron into $2s2{p}^{6}\phantom{\rule{0.16em}{0ex}}(np)$ Rydberg series, broadband NIR couple $2s2{p}^{6}3p$ XUV-bright state neighboring $2s2{p}^{6}3s$ $2s2{p}^{6}3d$ XUV-dark states....
<title>Abstract</title> Photoinduced biological and chemical reactions are often based on key structural transformations of a molecule driven across multiple electronic states. Acetylacetone (AcAc) is prototypical system for complex pathways involving several conical intersections (CI) singlet-triplet intersystem crossings (ISC) characterized by distinct geometries. In the gas phase, AcAc predominantly in planar ring-like enolic form stabilized strong intramolecular O-H∙∙∙O hydrogen bond....
To improve the utility of ultrafast infrared spectroscopy experiments, we have developed and actively compressed a tunable broadband mid-IR (BBIR) source. The octave-spanning BBIR source is generated by filamentation process 800 400 nm pulses in pressurized gas cell. correct higher-order dispersion effects pulses, introduced deformable mirror grating compressor, which uses an iterative genetic algorithm with optical feedback. Compression yields nearly transform-limited 21 fs, or ∼1.4 cycles...
Nonlinear spectroscopies can disentangle spectra that are congested due to inhomogeneous broadening. In conjunction with theoretical calculations, attosecond extreme ultraviolet (XUV) four-wave-mixing (FWM) spectroscopy is utilized here probe the dynamics of autoionizing inner valence excited Rydberg states polyatomic molecule, ${\mathrm{CO}}_{2}$. This tabletop nonlinear technique employs a short XUV pulse train and two noncollinear, few-cycle near-infrared pulses generate background-free...
The Raman spectrum of the symmetric stretching vibration (ν 1 ) liquid carbon tetrachloride observed at 295 K and reported repeatedly over last 80 years clearly shows four five more abundant isotopomers 440–470 cm −1 . At lower energy end this spectrum, additional intensity due to isotopomeric contributions from stretch for v = → 2 (hotbands) partially overlaps prominent 0 features, accounts about 18% integrated in agreement with theory. When these two patterns are modeled subtracted...
Raman spectroscopy is a powerful experimental technique, yet it often missing from the undergraduate physical chemistry laboratory curriculum. Tetrachloromethane (CCl4) ideal molecule for an introductory vibrational experiment and symmetric stretch vibration contains fine structure due to isotopic variations of according C35Clx37Cl4–x. We report simple theoretical predictions structure, calculation differential scattering cross sections, discussion inherent asymmetry in v1 mode resulting...
In our previous article on CCl4 in this Journal, we presented an investigation of the fine structure symmetric stretch carbon tetrachloride (CCl4) due to isotopic variations chlorine C35Clx37Cl4–x. paper, present contributions from both v = 0 1 excitation and 2 excitation. We report calculation spectral excited state vibrational transitions (hot bands). All calculations discussion are appropriate for undergraduate physical chemistry laboratory as either independent dry lab or a supplement...
Femtosecond X-ray absorption and emission spectroscopies are used at the Fe K-edge to directly monitor transient oxidation states orbital occupancy during charge transfer in a series of solvated mixed-valence complexes.
We present a deformable mirror pulse shaper designed to compress broadband mid-IR pulses between 3 and 7 μm. The electric fields of the nearly transform limited octave-spanning IR are retrieved using XFROG.
Two-dimensional electronic-vibrational spectroscopy is presented using a sequence of two ~40 fs 400 nm pulses and an octave-spanning broadband mid-IR pulse (~20 fs) to measure correlated electronic vibrational dynamics.