Regeta K, Kumar S, Cunha T, Mendes M, Lozano A I, Pereira P J S, García G, Moutinho A M C, Bacchus-Montabonel M-C, Limão-Vieira P
Atomic and Molecular Collisions Laboratory, CEFITEC, Department of Physics, Universidade NOVA de Lisboa, 2829-516 Caparica, Portugal.
Department of Mathematics, Instituto Superior de Engenharia de Lisboa, R. Conselheiro Emídio Navarro 1, 1959-007 Lisboa, Portugal.
J Phys Chem A. 2020 Apr 23;124(16):3220-3227. doi: 10.1021/acs.jpca.0c02076. Epub 2020 Apr 8.
Negative ion formation in electron transfer experiments from fast neutral potassium (K) atom collisions with neutral tetrachloromethane (CCl) molecules has been investigated in the laboratory frame range of 8-1000 eV. Comprehensive calculations on the electronic structure were performed for CCl in the presence of a potassium atom and used to help analyze the lowest unoccupied molecular orbitals participating in the collision process. Additionally, K energy loss produced in the forward direction has served to further our knowledge on the electronic state spectroscopy of CCl. A vertical electron affinity of -0.79 ± 0.20 eV has been obtained and assigned to a purely repulsive transition from CCl ground state to the T state of the temporary negative ion yielding Cl formation. Other features in the energy loss spectrum were observed for the first time and related to Cl, CCl, and CCl formation. Special attention is also given to the unresolved feature corresponding to a positive electron affinity of 0.24 ± 0.2 eV, assigned to a vibrationally hot transition from CCl ground state into the triply degenerate T excited state of the negative ion. The combined time-of-flight mass spectrometry together with K energy loss data represents the most comprehensive assignment of the tetrachloromethane anion yields and the role of CCl electronic states in collision induced dissociation to date.
在实验室8 - 1000电子伏特的能量范围内，研究了快速中性钾（K）原子与中性四氯化碳（CCl₄）分子碰撞的电子转移实验中的负离子形成过程。对存在钾原子情况下的CCl₄进行了电子结构的综合计算，并用于帮助分析参与碰撞过程的最低未占据分子轨道。此外，正向产生的K能量损失有助于增进我们对CCl₄电子态光谱的了解。已获得垂直电子亲和能为 -0.79 ± 0.20电子伏特，并将其归因于从CCl₄基态到产生Cl⁻形成的临时负离子的T态的纯排斥跃迁。首次观察到能量损失谱中的其他特征，并与Cl⁻、CCl₃⁻和CCl₂⁻的形成有关。还特别关注了对应于0.24 ± 0.2电子伏特正电子亲和能的未解析特征，该特征归因于从CCl₄基态到负离子的三重简并T激发态的振动热跃迁。飞行时间质谱与K能量损失数据相结合，代表了迄今为止对四氯化碳阴离子产率以及CCl₄电子态在碰撞诱导解离中的作用最全面的分析。
