Hassan Saba Zia, Tauch Jonas, Kas Milaim, Nötzold Markus, Carrera Henry López, Endres Eric S, Wester Roland, Weidemüller Matthias
Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120, Heidelberg, Germany.
Département de Chimie, Faculté des Sciences, Université Libre de Bruxelles (ULB), 1050, Brussels, Belgium.
Nat Commun. 2022 Feb 10;13(1):818. doi: 10.1038/s41467-022-28382-w.
Associative electronic detachment (AED) between anions and neutral atoms leads to the detachment of the anion's electron resulting in the formation of a neutral molecule. It plays a key role in chemical reaction networks, like the interstellar medium, the Earth's ionosphere and biochemical processes. Here, a class of AED involving a closed-shell anion (OH) and alkali atoms (rubidium) is investigated by precisely controlling the fraction of electronically excited rubidium. Reaction with the ground state atom gives rise to a stable intermediate complex with an electron solely bound via dipolar forces. The stability of the complex is governed by the subtle interplay of diabatic and adiabatic couplings into the autodetachment manifold. The measured rate coefficients are in good agreement with ab initio calculations, revealing pronounced steric effects. For excited state rubidium, however, a lower reaction rate is observed, indicating dynamical stabilization processes suppressing the coupling into the autodetachment region. Our work provides a stringent test of ab initio calculations on anion-neutral collisions and constitutes a generic, conceptual framework for understanding electronic state dependent dynamics in AEDs.
阴离子与中性原子之间的缔合电子脱离（AED）会导致阴离子的电子脱离，从而形成中性分子。它在化学反应网络中起着关键作用，如星际介质、地球电离层和生化过程。在此，通过精确控制电子激发铷的比例，研究了一类涉及闭壳层阴离子（OH）和碱金属原子（铷）的AED。与基态原子的反应会产生一个稳定的中间体复合物，其中电子仅通过偶极力结合。复合物的稳定性由进入自脱离流形的非绝热和绝热耦合的微妙相互作用决定。测量得到的速率系数与从头算计算结果吻合良好，揭示了明显的空间效应。然而，对于激发态铷，观察到较低的反应速率，这表明动力学稳定过程抑制了进入自脱离区域的耦合。我们的工作为阴离子-中性碰撞的从头算计算提供了严格检验，并构成了一个理解AED中电子态依赖动力学的通用概念框架。
