Origin of Bath Gas Dependence in Unimolecular Reaction Rates
Origin of Bath Gas Dependence in Unimolecular Reaction Rates
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单分子反应速率中浴液气体依赖性的起源
DOI：
10.1021/acs.jpca.8b11081
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发表时间：
2019
期刊：
影响因子：
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通讯作者：
Akira Matsugi
中科院分区：
文献类型：
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作者：
Kazuki Morita;Yuta Kizaki;Nobutsuna Endo;Norihiro Kamamichi;森田和希，遠藤信綱，釜道紀浩;木﨑裕太，遠藤信綱，釜道紀浩;木﨑裕太，遠藤信綱，釜道紀浩;森田和希，遠藤信綱，釜道紀浩;遠藤信綱;Akira Matsugi;Akira Matsugi;Akira Matsugi;Akira Matsugi
热单分子反应速率对浴气的依赖是由反应物与第三体分子碰撞的不同速率和效率引起的。本研究旨在通过甲基异氰化物（methyl isoocyanide, CH3NC）与15种不同的浴气分子（CH3NC、He、Ar、H2、N2、CO、CO2、HCN、NH3、CH4、CH3F、CF4、C2H2、C2H4和C2H6）碰撞的经典轨迹来揭示这种依赖的机制起源。根据轨迹计算，对碰撞频率、能量传递参数和相对第三体效率进行了评估。所研究的浴气的相对第三体效率与现有的实验数据很好地吻合。结果表明，碰撞频率的差异是低压速率常数依赖于浴气的主要来源。远距离分子间相互作用的性质，特别是其各向异性，被认为是决定碰撞频率的关键因素。
The bath gas dependence of thermal unimolecular reaction rates arises from different rates and efficiencies of collisions between reactant and third-body molecules. This study aims to unravel the mechanistic origin of this dependence based on the classical trajectories of methyl isocyanide (CH3NC) colliding with 15 different bath gas molecules (CH3NC, He, Ar, H2, N2, CO, CO2, HCN, NH3, CH4, CH3F, CF4, C2H2, C2H4, and C2H6). The collision frequencies, energy transfer parameters, and relative third-body efficiencies are evaluated from the trajectory calculations. The relative third-body efficiencies of the studied bath gases are found to be in good agreement with available experimental data. The results indicate that differences in collision frequencies are the primary source of the bath gas dependence of the low-pressure rate constants. The nature of the long-range intermolecular interaction, particularly, its anisotropy, is suggested to play a key role in determining the collision frequency.