近日，西安交通大学任雪光团队研究了氢迁移在乙腈指示剂裂解动力学中的促进作用。相关论文于2025年4月14日发表在《物理评论A》杂志上。

研究组使用多粒子重合动量谱研究了乙腈的电子碰撞双电离和随后的裂解动力学。通过测量两体库仑爆炸过程的动能释放和反应坐标系中的势能计算，研究组确定了几个通常无法通过直接库仑爆炸进入的碎裂通道，这需要预先异构化，这在直接库仑爆炸通道中占主导地位。

势能计算表明，氢迁移降低了C-C键断裂的能量势垒，从而促进了乙腈离子的断裂。此外，研究组发现，漫游的H₂不是转移到氮原子产生双氢迁移通道，而是捕获质子或将电子转移到剩余部分，导致H₃⁺和H₂⁺阳离子的形成。这项工作提供了对分子破碎中氢迁移和库仑爆炸机制之间竞争相互作用的见解。

附：英文原文

Title: Facilitating role of hydrogen migration in the fragmentation dynamics of acetonitrile dications

Author: Qibo Ma, Jiaqi Zhou, Xiaorui Xue, Xintai Hao, Enliang Wang, Xueguang Ren

Issue&Volume: 2025/04/14

Abstract: We investigate the electron-impact double ionization and subsequent fragmentation dynamics of acetonitrile using multiparticle coincident momentum spectroscopy. Through the measurements of the kinetic energy release for the two-body Coulomb explosion processes and the potential energy calculations in the reaction coordinate, we identify several fragmentation channels that are typically not accessible via direct Coulomb explosion, necessitating prior isomerization, which dominates over the direct Coulomb explosion channel. The potential energy calculations reveal that hydrogen migration reduces the energy barrier of C-C bond cleavage, thereby promoting the fragmentation of acetonitrile dications. Moreover, we find that, instead of transferring to the nitrogen atom yielding the double hydrogen migration channel, the roaming H2 captures a proton or transfers an electron to the remaining moiety, leading to the formation of H3+ and H2+ cations. This work provides insight into the competitive interplay between hydrogen migration and Coulomb explosion mechanisms in molecular fragmentation.

DOI: 10.1103/PhysRevA.111.042817

Source: https://journals.aps.org/pra/abstract/10.1103/PhysRevA.111.042817