A5066038125- Geological and Geochemical Analysis
- Spectroscopy and Quantum Chemical Studies
- Advanced Chemical Physics Studies
- Geochemistry and Geologic Mapping
- Photochemistry and Electron Transfer Studies
- Urban Heat Island Mitigation
- Spectroscopy and Laser Applications
- Calibration and Measurement Techniques
- Cryospheric studies and observations
- Planetary Science and Exploration
- Fullerene Chemistry and Applications
- Earthquake Detection and Analysis
- Atmospheric and Environmental Gas Dynamics
- Mass Spectrometry Techniques and Applications
- Graphene research and applications
- Laser-Matter Interactions and Applications
- Nuclear Physics and Applications
- earthquake and tectonic studies
- Remote-Sensing Image Classification
- Electron and X-Ray Spectroscopy Techniques
- Free Radicals and Antioxidants
- Landslides and related hazards
- Infrared Target Detection Methodologies
- Hydrocarbon exploration and reservoir analysis
- Molecular spectroscopy and chirality
Baylor University
1998-2024
Rutherford Appleton Laboratory
2024
Bureau of Economic Analysis
2024
The University of Texas at Austin
2024
University of Pittsburgh
2019-2023
Central Laser Facility
2023
University of Nottingham
2020-2021
Heriot-Watt University
2012-2019
University of Missouri
2017-2019
University of Edinburgh
2015-2018
Time-resolved photoelectron imaging was used to investigate the dynamical evolution of initially prepared S(1) (ππ*) excited state phenol (hydroxybenzene), catechol (1,2-dihydroxybenzene), resorcinol (1,3-dihydroxybenzene), and hydroquinone (1,4-dihydroxybenzene) following excitation at 267 nm. Our analysis supported by ab initio calculations coupled-cluster CASSCF levels theory. In all cases, we observe rapid (<1 ps) intramolecular vibrational redistribution on potential surface. catechol,...
Time-resolved photoelectron imaging was used to investigate the electronic relaxation dynamics of gas-phase aniline, N, N-dimethylaniline, and 3,5-dimethylaniline following ultraviolet excitation at 250 nm. Our analysis supported by ab initio coupled-cluster calculations evaluating excited state energies (in aniline) evolution a range physical properties as function N–H bond extension. Due lack consistency between several earlier studies undertaken in specific aim this present work gain new...
Since the advent of ion imaging, one key issues in field has been creating methods to reconstruct initial 3D distribution particles from its 2D projection. This led development a number different numerical and fitting techniques solve this fundamental issue imaging. In recent years, slice-imaging have developed that permit direct recording distribution, i.e., thin slice recoiling fragment distribution. However, practice, most imaging experiments achieve velocity width around 10%–25% center...
High temporal resolution, geostationary, thermal infrared data from the Advanced Baseline Imager combined with seismic of La Soufrière Volcano, St. Vincent provide empirical insights into volcanic processes and mechanisms that occurred November 2020 until explosive phase in April 2021. An overall increase intensity output seismicity are observed during effusive phase; however, increased ∼20 days earlier than seismicity. During phase, daily radiant heat flux 0.01 to >100 MW 1 647 events. The...
Using a combination of ultrafast solution- and gas-phase spectroscopies, together with high-level theory calculations, we demonstrate that are able to track conformer-specific photodissociation dynamics in solution through solvent choice. We reveal this phenomenon guaiacol (2-methoxyphenol), key subunit the natural biopolymer lignin. In cyclohexane, first electronically excited (1)ππ* (S1) state relaxes time-constant τ = 4.5 ± 0.2 ns, mediated intersystem crossing lower lying triplet (Tn)...
Time-resolved photoelectron imaging was used to study non-adiabatic relaxation dynamics in <italic>N</italic>,<italic>N</italic>-dimethylisopropylamine, <italic>N</italic>,<italic>N</italic>-dimethylpropylamine and <italic>N</italic>-methylpyrrolidine following excitation at 200 nm.
To describe the arterial vascular anatomy in area of sacrospinous ligament.Cadaver pelvises were dissected to reveal ligament with emphasis on and neuroanatomy. Flexible rulers used measure coccygeal branch five hemipelvises.The pudendal vessels nerve pass immediately medial inferior ischial spine (within 0.5 cm spine) behind ligament. The artery lies anterior sacrotuberous ligament, which passes its attachment at posterior tuberosity. gluteal originates from or internal iliac sciatic There...
Time-resolved photoelectron spectroscopy reveals distinct ionization signatures of Rydberg-to-valence state evolution in the secondary aliphatic amine piperidine.
Time-resolved photoelectron imaging was used to investigate the relaxation dynamics of electronically excited aniline in gas-phase following ultraviolet irradiation 273-266 nm region. We find that at all wavelengths studied, excitation is predominantly long-lived (>1 ns) S1(ππ(*)) state, which exhibits ultrafast intramolecular vibrational redistribution on a <1 ps timescale. At centred resonant transitions absorption spectrum have previously been assigned higher lying S2(3s∕πσ(*)) we also...
Although time-sliced imaging yields improved signal-to-noise and resolution compared with unsliced velocity mapped ion images, for finite slice widths as encountered in real experiments there is a loss of recovered intensities the slow fragments. Recently, we reported new approach that permits correction these effects an arbitrarily sliced distribution 3D charged particle cloud. This analysis (FinA) method utilizes basis functions model out-of-plane contribution given component to image...
Several high spatial resolution thermal infrared (TIR) missions are planned for the coming decade and their data will be crucial to constrain volcanic activity patterns throughout pre- post-eruption phases. Foundational these is subtle (1−2 K) behavior, which easily overlooked using lower data. In preparation new data, we conducted first study entire twenty-two-year archive of higher spatial, temporal TIR from Advanced Spaceborne Thermal Emission Reflection Radiometer (ASTER) sensor. This...
Abstract Modeling lava flow propagation is important to determine potential hazards local populations. Thermo-rheological models such as PyFLOWGO track downflow cooling and rheological responses for open-channel, cooling-limited flows. The dominant radiative component governed partly by the emissivity, which a material property that governs efficiency. Emissivity commonly treated constant in models, but shown here vary with temperature. To establish effect of temperature on high...
Abstract First measurements of the emission lava worlds with James Webb Space Telescope (JWST) probe conditions on so hot that their surfaces are likely molten or partially molten. These observations provide a unique opportunity to explore rocky planets’ evolution. Surfaces world exoplanets can give insights into composition and interior workings. However, data spectral emissivity wide range potential exoplanet surface compositions temperatures is required understand JWST data. Here, we...
We present state-to-state differential cross sections for collisions of NO molecules (X2Π1/2,j=1/2,f) with He atoms and ortho-D2 (j = 0) as a function collision energy. A high angular resolution obtained using the combination Stark deceleration velocity map imaging allows observation diffraction oscillations in scattering distributions. Differences and, particular, differences spacing between individual peaks are observed. Since masses D2 almost equal since D2(j may be considered...
PES and STM studies show that the encapsulated Li strongly influences properties of diffuse Li@C<sub>60</sub>SAMO excited states.
Time-resolved photoelectron imaging reveals subtle new mechanistic insight into the ultraviolet relaxation dynamics of gas-phase indole.
The electronic structure and photoinduced dynamics of fullerenes, especially C60, is great interest because these molecules are model systems for more complex nanomaterials. In this work we have used Rydberg Fingerprint Spectroscopy to determine the relative ionization intensities from excited SAMO (Rydberg-like) states in C60 as a function laser wavelength. then compared ratio photoionization widths Rydberg-like states, computed time-dependent density functional theory (TD-DFT). agreement...
We have developed a new portable, ground-based imaging system primarily to investigate the thermal properties of volcanic processes during lava propagation and cooling, although it is potentially applicable any dynamic geologic process. The miniature multispectral camera (MMT-Cam) an that acquires six wavelength bands infrared (TIR) data between 8 12 μm nearly simultaneously. spatial temporal resolutions are high, 640 × 512 pixels, 1 s, respectively. calibrated using full-aperture blackbody...
We report time-resolved photoelectron imaging studies of gas-phase pyrrole over the 267-240 nm excitation region, recorded in conjunction with a 300 probe. Of specific interest is lowest-lying (3s/πσ*) state, which exhibits very weak oscillator strength but thought to be excited directly at wavelengths ≤254 nm. conclude, however, that only significant contribution our data all investigated from non-resonant ionization. Our findings do not rule out state (as appears confirmed by supporting...
The faces of volcanic phenocrysts may be marked by imperfections occurring as holes that penetrate the crystal interior. When filled with glass these features, called embayments or reentrants, have been used to petrologically constrain magmatic ascent rate. Embayment speedometry relies on record disequilibrium preserved diffusion-limited volatile concentration gradients in embayment glass. Clear, glassy are carefully selected for studies. use and subsequent descriptions pristine...
Spaceborne detection and measurements of high-temperature thermal anomalies enable monitoring forecasts lava flow propagation. The accuracy such estimates relies on the knowledge input parameters, as emissivity, which notably affects computation temperature, radiant heat flux, subsequent analyses (e.g., effusion rate distance to run) that rely observations. To address deficit field laboratory-based emissivity data for inverse forward modelling, we measured ‘a’a samples from 2001 Mt. Etna...
Abstract One of the top priorities Surface Biology and Geology (SBG) Earth Observing System is detection retrieval elevated temperature features (ETF) usually found in vicinity active fires volcanic activity. We test ability currently proposed midwave (MIR: 3–5 μm) thermal infrared (TIR: 8–12 bands to detect ETF within 400–1200 K range. Specifically, our investigation aims compare contrast use 4 4.8 μm MIR bands. land surface data obtained by airborne Hyperspectral Thermal Emission...
Active lava surfaces emplaced during effusive eruptions are typically observed in the form of flows, lakes, or domes. There numerous volcanoes on Earth that regularly produce active including Kīlauea volcano Hawai'i, which had a continually-active flow field from 1980s until end last eruptive phase 2018. During decade period, it also persistent lake at summit. This study used new ground-based Miniature Multispectral Thermal Camera (MMT-Cam) imaging system to acquire high-spatiotemporal data...