A5018648223- Atmospheric chemistry and aerosols
- Catalysis and Oxidation Reactions
- Advanced Chemical Physics Studies
- Catalytic Processes in Materials Science
- Advanced Combustion Engine Technologies
- Machine Learning in Materials Science
- Various Chemistry Research Topics
- Analytical Chemistry and Chromatography
- Combustion and flame dynamics
- Free Radicals and Antioxidants
- Computational Drug Discovery Methods
- Chemical Thermodynamics and Molecular Structure
- Spectroscopy and Laser Applications
- Atmospheric Ozone and Climate
- Inorganic and Organometallic Chemistry
- Chemical Synthesis and Analysis
- Mass Spectrometry Techniques and Applications
- Thermal and Kinetic Analysis
- Gene Regulatory Network Analysis
- Air Quality and Health Impacts
- Scientific Computing and Data Management
- Photochemistry and Electron Transfer Studies
- Radioactive element chemistry and processing
- Protein Structure and Dynamics
- Parallel Computing and Optimization Techniques
Sandia National Laboratories California
2016-2025
Sandia National Laboratories
2009-2025
Shanghai Jiao Tong University
2023
Lawrence Livermore National Security
2014-2018
Massachusetts Institute of Technology
2017
Cyprus Institute
2017
Hungarian Academy of Sciences
2008-2010
National Technical Information Service
2009
Office of Scientific and Technical Information
2009
Eötvös Loránd University
2003-2008
Oxidation of organic compounds in combustion and Earth's troposphere is mediated by reactive species formed the addition molecular oxygen (O2) to radicals. Among most crucial elusive these intermediates are hydroperoxyalkyl radicals, often denoted "QOOH." These their reactions with O2 responsible for radical chain branching that sustains autoignition implicated tropospheric autoxidation can form low-volatility, highly oxygenated aerosol precursors. We report direct observation kinetics...
Stationary points on the C(3)H(7)O potential energy surface relevant to title reaction are calculated employing RQCISD(T)/cc-pVinfinityZ//B3LYP/6-311++G(d,p) quantum chemical calculations. Rate coefficients at 50-3000 K temperature and from zero infinite pressure using an RRKM-based multiwell master equation. Due topography of entrance channel effective two-transition-state model is used calculate accurate association rate coefficients. Our calculations in excellent agreement with available...
Ketohydroperoxides are important in liquid-phase autoxidation and gas-phase partial oxidation pre-ignition chemistry, but because of their low concentration, instability, various analytical chemistry limitations, it has been challenging to experimentally determine reactivity, only a few pathways known. In the present work, 75 elementary-step unimolecular reactions simplest γ-ketohydroperoxide, 3-hydroperoxypropanal, were discovered by combination density functional theory with several...
The branched C5 alcohol isopentanol (3-methylbutan-1-ol) has shown promise as a potential biofuel both because of new advanced biochemical routes for its production and combustion characteristics, in particular fuel homogeneous-charge compression ignition (HCCI) or related strategies. In the present work, fundamental autoignition chemistry is investigated by using technique pulsed-photolytic Cl-initiated oxidation analyzing reacting mixture time-resolved tunable synchrotron photoionization...
We present a theoretical study of degradation mechanisms for photoinduced oxidation in organic polymers the condensed phase, using poly(3-hexylthiophene)(P3HT) as an example. Applying density functional theory with hybrid and periodic boundary conditions that account steric effects permit modeling interchain chemical reactions, we investigate reaction pathways may lead to thiophene backbone critical step toward disrupting polymer conjugation. calculate energy barriers reactions P3HT...
Local and global uncertainty analyses of a flat, premixed, stationary, laminar methane flame model were carried out using the Leeds oxidation mechanism at lean (phi = 0.70), stoichiometric 1.00), rich 1.20) equivalence ratios. Uncertainties velocity, maximal temperature, concentrations radicals H, O, OH, CH, CH(2) investigated. Global analysis methods included Morris method, Monte Carlo with Latin hypercube sampling, an improved version Sobol' method. Assumed probability density functions...
Abstract. Model-measurement comparisons of HOx in extremely clean air ([NO]<3 ppt) are reported. Measurements were made during the second Southern Ocean Photochemistry Experiment (SOAPEX-2), held austral summer 1999 at Cape Grim Baseline Air Pollution Station north-western Tasmania, Australia. The free-radical chemistry was studied using a zero-dimensional box-model based upon Master Chemical Mechanism (MCM). Two versions model used, with different levels chemical complexity, to explore...
The OH concentration in the Cl-initiated oxidation of cyclohexane has been measured between 6.5–20.3 bar and 586–828 K temperature range by a pulsed-laser photolytic initiation–laser-induced fluorescence method. experimental profiles are modeled using master-equation-based kinetic model as well comprehensive literature mechanism. Below ∼700 formation takes place on two distinct time-scales, one order microseconds other over milliseconds. Detailed modeling demonstrates that "formally direct"...
Hydrocarbon autoignition has long been an area of intense fundamental chemical interest, and is a key technological process for emerging clean efficient combustion strategies. Carbon-centered radicals containing -OOH group, commonly denoted ˙QOOH radicals, are produced by isomerization the alkylperoxy that formed in first stages oxidation. These among most critical species modeling autoignition, as their reactions with O2 responsible chain branching below 1000 K. Despite importance, no have...
The automated kinetics workflow code, KinBot, was used to explore and characterize the regions of C7H7 potential energy surface that are relevant combustion environments especially soot inception. We first explored lowest-energy region, which includes benzyl, fulvenallene + H, cyclopentadienyl acetylene entry points. then expanded model include two higher-energy points, vinylpropargyl vinylacetylene propargyl. search able uncover pathways from literature. In addition, three important new...
We assess the capability of machine-learned potentials to compute rate coefficients by training a neural network (NN) model and applying it describe chemical landscape on C5H5 potential energy surface, which is relevant molecular weight growth in combustion interstellar media. coupled resulting NN with an automated kinetics workflow code, KinBot, perform all necessary calculations coefficients. The benchmarked exhaustively evaluating its performance at various stages calculations: from...
Microkinetic models for catalytic systems require estimation of many thermodynamic and kinetic parameters that can be calculated isolated species transition states using ab initio methods. However, the presence nearby co-adsorbates on surface dramatically alter these causing them to dependent coverage fractions. As there are combinatorially co-adsorbed configurations surface, computing dependence is far less straightforward. We present a framework generating applying machine learning predict...
The resonance-stabilized cyclopentadienyl (C5H5) and propargyl (C3H3) radicals are important precursors for polycyclic aromatic hydrocarbons (PAHs) thus play a significant role in molecular-weight growth soot formation processes under combustion conditions. In this work, we describe an experimental theoretical investigation of the C5H5 + C3H3 reaction. Experimentally, studied reaction resistively heated microtubular SiC reactor at controlled temperature ∼1150 K pressure 10-20 mbar. reactants...
Abstract Local and Monte Carlo uncertainty analyses of NO production during methane combustion were carried out, investigating the effect uncertainties kinetic parameters enthalpies formation. In Case I, original Leeds oxidation mechanism with x reaction block was used, but formation all species updated. II, NCN‐containing reactions prompt route added rate several also The examined at conditions Bartok et al. experiments (PSR, T = 1565–1989 K, φ 0.8–1.2, residence time 3 ms). analysis...