Department of Chemistry, Michigan State University, East Lansing, Michigan 48824, USA.
J Chem Phys. 2018 Dec 28;149(24):244310. doi: 10.1063/1.5065387.
Roaming chemical reactions are often associated with neutral molecules. The recent findings of roaming processes in ionic species, in particular, ones that lead to the formation of H under strong-field laser excitation, are of considerable interest. Given that such gas-phase reactions are initiated by double ionization and subsequently facilitated through deprotonation, we investigate the strong-field photodissociation of ethanethiol, also known as ethyl mercaptan, and compare it to results from ethanol. Contrary to expectations, the H yield was found to be an order of magnitude lower for ethanethiol at certain laser field intensities, despite its lower ionization energy and higher acidity compared to ethanol. In-depth analysis of the femtosecond time-resolved experimental findings, supported by quantum mechanical calculations, provides key information regarding the roaming mechanisms related to H formation. Results of this study on the dynamics of dissociative half-collisions involving H , a vital cation which acts as a Brønsted-Lowry acid protonating interstellar organic compounds, may also provide valuable information regarding the formation mechanisms and observed natural abundances of complex organic molecules in interstellar media and planetary atmospheres.
roaming 反应通常与中性分子有关。最近在离子物种中发现 roaming 过程，特别是在强场激光激发下导致 H 的形成，这引起了相当大的兴趣。鉴于此类气相反应是通过双电离引发的，随后通过去质子化得到促进，我们研究了乙硫醇（也称为乙基硫醇）的强场光解，并将其与乙醇的结果进行了比较。出乎意料的是，尽管乙硫醇的电离能较低且酸度较高，但在某些激光场强度下，其 H 的产率比乙醇低一个数量级。飞秒时间分辨实验结果的深入分析，得到了量子力学计算的支持，为与 H 形成相关的 roaming 机制提供了关键信息。这项关于涉及 H 的离解半碰撞动力学的研究结果，H 是一种重要的阳离子，它作为布朗斯特-劳里酸，质子化星际有机化合物，也可能为星际介质和行星大气中复杂有机分子的形成机制和观测到的自然丰度提供有价值的信息。
