A5076775259- Seismic Waves and Analysis
- Methane Hydrates and Related Phenomena
- Ionosphere and magnetosphere dynamics
- Earthquake Detection and Analysis
- Geophysics and Gravity Measurements
- Advanced Chemical Physics Studies
- X-ray Diffraction in Crystallography
- Radioactive element chemistry and processing
- Photochemistry and Electron Transfer Studies
- Crystallization and Solubility Studies
- Clay minerals and soil interactions
- Electrochemical Analysis and Applications
- Electrocatalysts for Energy Conversion
- Advanced ceramic materials synthesis
- Catalytic Processes in Materials Science
- Spectroscopy and Quantum Chemical Studies
- Catalysis and Oxidation Reactions
- Free Radicals and Antioxidants
- Atmospheric chemistry and aerosols
- Mass Spectrometry Techniques and Applications
- Zeolite Catalysis and Synthesis
- Advanced NMR Techniques and Applications
- X-ray Spectroscopy and Fluorescence Analysis
- Chemical Synthesis and Characterization
- NMR spectroscopy and applications
Pacific Northwest National Laboratory
2015-2024
Environmental Molecular Sciences Laboratory
2015-2024
Battelle
2015-2019
Richland College
2016-2019
The Ohio State University
2017
Physical Sciences (United States)
2016
John Wiley & Sons (United States)
2011
University of California, Los Angeles
2002-2003
University of Utah
2000
The promoting role of lanthanum oxide (La2O3) in the catalytic synthesis mixed higher (C2–C6) alcohols from syngas on Co-based catalysts was investigated using a combination situ and ex X-ray diffraction (XRD), photoelectron spectroscopy (XPS), catalyst reactivity performance studies, ab initio molecular dynamics (AIMD) simulations. XRD measurements show that doping with La (0.5 wt %) onto activated carbon (AC) supported Co enhances Co2C phase formation, whereas formation is largely...
In the liquid-phase catalytic processing of molecules using heterogeneous catalysts—an important strategy for obtaining renewable chemicals from biomass—many key reactions occur at solid–liquid interfaces. particular, glucose isomerization occurs when is adsorbed in micropores a zeolite catalyst. Since solvent are coadsorbed, activity depends strongly and often nonmonotonically on composition. For catalyzed by NaX NaY zeolites, there an initial steep decline water mixed with small amount...
Molecular clustering and associated dynamic processes of lithium polysulfide species were unraveled using classical molecular dynamics ab initio metadynamics calculations. The spectroscopic signatures clusters analyzed a multimodal analysis including experimental computational nuclear magnetic resonance (NMR) X-ray absorption spectroscopies. Lithium solutes (Li2S4, Li2S6, Li2S8) their mixtures in 1,3-dioxolane 1,2-dimethoxyethane (DOL/DME) solvent undergo aggregation driven by intramolecular...
The crystallography of transition Al2O3 has been extensively studied in the past, because advantageous properties oxide catalytic and a range other technological applications. However, existing crystallographic models are insufficient to describe structure many important polymorphs, their highly disordered nature. In this work, we investigate disorder high-temperature-treated provide structural description for θ-Al2O3 by using suite complementary imaging, spectroscopy, quantum calculation...
We present a joint experimental and computational study of the hexacyanoferrate aqueous complexes at equilibrium in 250 meV to 7.15 keV regime. The experiments computations include vibrational spectroscopy cyanide ligands, valence electronic absorption spectra, Fe 1s core hole spectra using element-specific-resonant X-ray emission techniques. Density functional theory-based quantum mechanics/molecular mechanics molecular dynamics simulations are performed generate explicit solute-solvent...
High-temperature treatment of γ-Al2 O3 can lead to a series polymorphic transformations, including the formation δ-Al2 and θ-Al2 . Quantification microstructure in range where δ- are formed represents formidable challenge, as both phases accommodate high degree structural disorder. In this work, we explore use an XRD recursive-stacking formalism for quantification high-temperature transition aluminas. We formulate methodology modelling disorder twinning show that explicitly accounting is...
The sequential bond energies for complexes of Mg+ with CO, CO2, NH3, CH4, CH3OH, and C6H6 are determined by collision-induced dissociation (CID) xenon or argon in a guided ion beam tandem mass spectrometer. kinetic energy dependence the CID ligand exchange cross sections analyzed to yield 0 298 K Mg+−L after accounting effects multiple ion−molecule collisions, internal reactant ions, lifetimes. Bond (in eV) at L = Ar (0.10 ± 0.07), Xe (0.32 0.12), 1−2 CO (0.43 0.06 0.40 0.03), 1−3 CO2 (0.60...
Potassium- (K-) promoted MoS2 catalyst is a very promising used for synthesis of mixed higher alcohols from syngas. Herein, periodic density functional theory calculations were performed to investigate the interaction potassium with Mo and S edges MoS2(100) surface. Both neutral K- charged "K+"-promoted systems at different sulfur coverages studied. Our indicate that adsorbed K atom readily donates its single 4s valence electron structure, K+ show similar adsorption behavior. Isolated...
Periodic density functional theory calculations were performed to study the structural and electronic properties of potassium intercalated into hexagonal MoS2 (2H-MoS2). Metallic (K) atoms are incrementally loaded in sites interstitial spaces between layers 2H-MoS2 bulk structure generating KxMoS2 (0.125 ≤ x 1.0) structures. To accommodate atoms, spacing c parameter expands 15.871 Å K0.125MoS2. The second lowest loading concentration (K0.25MoS2) results largest expansion (to = 16.617 Å). Our...
Molecular recognition of an aqueous pertechnetate (TcO4(-)) anion is fundamentally challenging partly due to the charge-diffuse nature this anion, which hampers design new technologies for its separation and detection. To address gap, simple salts transition metal complexes that undergo a distinct spectroscopic change upon exposure anions were explored. The Pt(II) complex [Pt(tpy)Br]SbF6 (tpy = 2,2';6',2″-terpyridine) undergoes dramatic color intense luminescence response TcO4(-) uptake...
We investigate the controlled deposition of Keggin polyoxometalate (POM) anions, PMo12O403– and PMo12O402–, onto different self-assembled monolayer (SAM) surfaces via soft landing mass-selected ions. Utilizing in situ infrared reflection absorption spectroscopy (IRRAS), ex cyclic voltammetry (CV), electronic structure calculations, we examine charge retention supported multiply charged POM anions characterize redox properties modified surfaces. SAMs alkylthiol (HSAM), perfluorinated (FSAM),...
Molecular dynamics simulations, conventional and metadynamics, were performed to determine the interaction of model protein Gb1 over kaolinite (001), Na(+)-montmorillonite Ca(2+)-montmorillonite goethite (100), Na(+)-birnessite (001) mineral surfaces. Gb1, a small (56 residue) with well-characterized solution-state nuclear magnetic resonance (NMR) structure having α-helix, 4-fold β-sheet, hydrophobic core features, is used as study soil interactions gain insights on structural changes...
Aqueous organic redox flow batteries offer an environmentally benign, tunable, and safe route to large-scale energy storage. The density is one of the key performance parameters batteries, which critically depends on solubility redox-active molecule in water. Prediction aqueous remains a challenge chemistry. Recently, machine learning models have been developed for molecular properties prediction chemistry material science. fidelity model diversity, accuracy, abundancy training datasets. We...
In part I, we discussed the chain-propagating and possible competing mechanisms of low-temperature (300−1000 K) dimethyl ether (DME) combustion. Here consider chain-branching mechanism that results in explosive combustion, initiated by O2 addition to ·CH2OCH2OOH intermediate formed earlier chain-propagation step. Ideally, leads formation two highly reactive ·OH radicals from ·OOCH2OCH2OOH precursor. Each these can initiate a chain-reaction "branch" with another DME molecule, which, ideally,...
Non-monotonic catalytic behavior in an isoreticular MOF series results from subtle structural differences that alter the substrate binding energy.
Ligand substitution reactions are common in solvated transition metal complexes, and harnessing them through initiation with light promises interesting practical applications, driving interest new means of probing their mechanisms. Using a combination time-resolved x-ray absorption spectroscopy hybrid quantum mechanics/molecular mechanics (QM/MM) molecular dynamics simulations near-edge calculations, we elucidate the mechanism photoaquation model system iron(ii) hexacyanide, where UV...
We have performed detailed ground- and excited-state calculations of pure N-doped TiO2 rutile to model analyze the experimentally observed UV/vis spectrum. Using our embedding model, we both linear response (LR) real-time (RT) TDDFT excited states systems. also studied lowest excitations using high-level active space equation-of-motion coupled cluster (EOMCC) approaches involving all single interband double excitations. compare contrast nature in detail for doped systems provide an analysis...
Metal fluorides with high redox potential and capacity from strong metal–fluoride bond conversion reaction make them promising cathodic materials. However, detailed lithium insertion extraction mechanisms have not yet been clearly understood explained. Here we report low-temperature synthesis of electrochemically active FeF3/FeF2 nanoparticles by catalytic decomposition a fluoropolymer [perfluoropolyether (PFPE)] using hydrated iron oxalate precursor both in air inert atmosphere. Freshly...
Matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) can provide spatially resolved molecular information about a sample. Recently, postionization approach (MALDI-2) has been commercially integrated with MALDI-MSI, allowing for bettered sensitivity and consequent improved spatial resolution. While advantages of MALDI-2 have previously established, we demonstrate here statistically increased in-source fragmentation (ISF) results from commercial instrument. Via...
Mineral-associated soil organic matter (SOM) is critical for stabilizing carbon and mitigating climate change. However, mineral-SOM interactions at the molecular scale, particularly synergetic adsorption through organic–organic interaction on mineral surface known as multilayering, remain poorly understood. This study investigates impact of multilayering interactions, by integrating macroscale experiments molecular-scale simulations that assess individual sequential major SOM...
Characterization and modeling of the molecular-level behavior simple hydrocarbon gases, such as methane, in presence both nonporous nanoporous mineral matrices allows for predictive understanding important processes engineered natural systems. In this study, changes local electromagnetic environments carbon atoms methane under conditions high pressure (up to 130 bar) moderate temperature 346 K) were observed with 13C magic-angle spinning (MAS) NMR spectroscopy while gas was mixed two model...
We present an implementation of a time-dependent semiempirical method (INDO/S) in NWChem using real-time (RT) propagation to address, principle, the entire spectrum valence electronic excitations. Adopting this model, we study UV/vis spectra medium-sized systems such as P3B2 and f-coronene, addition much larger ubiquitin gas phase betanin chromophore presence two explicit solvents (water methanol). RT-INDO/S provides qualitatively often quantitatively accurate results when compared with RT-...
The solvation free energy of organic molecules is a critical parameter in determining emergent properties such as solubility, liquid-phase equilibrium constants, and pKa redox potentials an flow battery. In this work, we present machine learning (ML) model that can learn predict the aqueous molecule using Gaussian process regression method based on new molecular graph kernel. To investigate performance ML electrostatic interaction, nonpolar interaction contribution solvent conformational...
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...