Zhang Shuwen, Hu Xixi, Xie Daiqian
Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China.
Kuang Yaming Honors School, Jiangsu Key Laboratory of Vehicle Emissions Control, Center of Modern Analysis, Nanjing University, Nanjing 210023, China.
J Phys Chem A. 2024 Aug 15;128(32):6695-6702. doi: 10.1021/acs.jpca.4c03970. Epub 2024 Aug 7.
The CH + OH reaction is a key elementary reaction in acetylene oxidation, and the products forming in different reaction channels, such as CH and CH radicals, are also important for subsequent reaction processes in the combustion process. In this work, we investigated the dynamics of the CH + OH reaction with specific vibrational mode excitations and analyzed the mode specificity based on quasi-classical trajectory calculations on a recently developed full-dimensional potential energy surface. It is found that exciting OH stretching mode can promote the production of H + OCCH and CO + CH, while the excitation of C-H symmetric/antisymmetric stretching mode of CH can facilitate the HO + CH channel. Based on the prediction of vibrationally adiabatic and sudden vector projection models, the mode specificity in the CH + OH reaction can be attributed to the difference in the degree of coupling between the initial motion mode and the reaction coordinate of each reaction path, which ultimately leads to the changes in rate constants and the product branching ratios. These findings can offer theoretical insights to regulate the branching ratio of the multichannel CH + OH reaction.
CH + OH反应是乙炔氧化中的一个关键基元反应，在不同反应通道中形成的产物，如CH和CH自由基，对于燃烧过程中的后续反应过程也很重要。在这项工作中，我们研究了具有特定振动模式激发的CH + OH反应的动力学，并基于在最近开发的全维势能面上的准经典轨迹计算分析了模式特异性。研究发现，激发OH伸缩模式可促进H + OCCH和CO + CH的生成，而激发CH的C - H对称/反对称伸缩模式则有利于HO + CH通道。基于振动绝热和突然矢量投影模型的预测，CH + OH反应中的模式特异性可归因于每个反应路径的初始运动模式与反应坐标之间的耦合程度差异，这最终导致速率常数和产物分支比的变化。这些发现可为调控多通道CH + OH反应的分支比提供理论见解。
