Theoretical Investigation of the Radical鈥揜adical Reaction of O(3P) + C2H3 and Comparison with Gas-Phase Crossed-Beam Experiments

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• 作者：Se-Hee Jung ; Su-Chan Jang ; Jin-Wook Kim ; Jang-Woon Kim ; Jong-Ho Choi
• 刊名：Journal of Physical Chemistry A
• 出版年：2015
• 出版时间：December 10, 2015
• 年：2015
• 卷：119
• 期：49
• 页码：11761-11771
• 全文大小：588K
• ISSN：1520-5215

文摘

Herein, we present an ab initio study of the prototypal radical鈥搑adical reactions of ground-state atomic oxygen [O(³P)] with the vinyl (C₂H₃) radical using density functional theory and a complete basis set model. Two distinctive pathways on the lowest doublet potential energy surfaces (PESs) were predicted to be in competition: addition and abstraction. The barrierless addition of O(³P) to the hydrocarbon radicals leads to energy-rich intermediate formation followed by subsequent isomerization and decomposition to yield various products: CH₂CO (ketene) + H, CO + CH₃, C₂HOH (acetylenol) + H, ^3,1CCHOH + H, H₂O + C₂H, ^3,1CH₂ + HCO, H₂CO (formaldehyde) + CH, C₂H₂ (acetylene) + OH, and ^3,1CCH₂ + OH. The competing but minor H-atom abstraction mechanisms produce C₂H₂ + OH and ^1,3CCH₂ + OH. The optimized structures of the reactants, products, intermediates, and transition states and the reaction mechanisms were obtained on the lowest doublet PESs. The major pathway was predicted to be the formation of CH₂CO + H through the low-barrier, single-step cleavages of the addition intermediates. The Levine鈥揃ernstein prior method, statistical surprisal approach, and microcanonical Rice鈥揜amsperger鈥揔assel鈥揗arcus theory were applied to deduce the energy distributions of H atoms and OH products and quantitative rate constants. On the basis of the statistical theory and the population analysis, the predicted energy distributions were compared to the kinetic energy release of H and the preferential population of the 螤(A鈥? component of OH products reported in recent gas-phase crossed-beam investigations (Park, M. J.; Jang, S. C.; Choi, J. H. J. Chem. Phys. 2012, 137, 204311), and their kinetic and dynamic characteristics were discussed.