Zhang Yu, Ren Baihui, Yang Chuan-Lu, Wei Long, Wang Bo, Han Jie, Yu Wandong, Qi Yueying, Zou Yaming, Chen Li, Wang Enliang, Wei Baoren
Key Laboratory of Nuclear Physics and Ion-beam Application (MOE), Institute of Modern Physics, Fudan University, 200433, Shanghai, China.
School of Mathematics, Physics and Information Engineering, Jiaxing University, 314001, Jiaxing, China.
Commun Chem. 2020 Nov 9;3(1):160. doi: 10.1038/s42004-020-00415-9.
Hydrogen migration plays an important role in the chemistry of hydrocarbons which considerably influences their chemical functions. The migration of one or more hydrogen atoms occurring in hydrocarbon cations has an opportunity to produce the simplest polyatomic molecule, i.e. H. Here we present a combined experimental and theoretical study of H formation dynamics from ethane dication. The experiment is performed by 300 eV electron impact ionization of ethane and a pronounced yield of H + CH coincidence channel is observed. The quantum chemistry calculations show that the H formation channel can be opened on the ground-state potential energy surface of ethane dication via transition state and roaming mechanisms. The ab initio molecular dynamics simulation shows that the H can be generated in a wide time range from 70 to 500 fs. Qualitatively, the trajectories of the fast dissociation follow the intrinsic reaction coordinate predicted by the conventional transition state theory. The roaming mechanism, compared to the transition state, occurs within a much longer timescale accompanied by nuclear motion of larger amplitude.
氢迁移在碳氢化合物化学中起着重要作用，这对其化学功能有很大影响。烃阳离子中一个或多个氢原子的迁移有机会产生最简单的多原子分子，即H。在此，我们展示了一项关于乙烷二价阳离子形成H动力学的实验与理论相结合的研究。实验通过对乙烷进行300 eV电子碰撞电离来进行，并观察到H + CH符合通道有显著产率。量子化学计算表明，H形成通道可通过过渡态和漫游机制在乙烷二价阳离子的基态势能面上打开。从头算分子动力学模拟表明，H可在70至500 fs的宽时间范围内产生。定性地说，快速解离的轨迹遵循传统过渡态理论预测的内禀反应坐标。与过渡态相比，漫游机制发生在长得多的时间尺度内，伴随着更大幅度的核运动。
