Electron-Molecule Temporary States: Vibronic Coupling in Excited Anions

在这个由化学部化学结构、动力学和机制A （CSDM-A）项目资助的项目中，圣路易斯华盛顿大学的Richard Mabbs教授正在研究分子与电子碰撞并暂时捕获电子时会发生什么。Mabbs研究小组对分子在电子捕获过程中如何振动和旋转特别感兴趣。这些结果对于充分理解电子转移/碰撞诱导化学特别重要，这些化学发生在化学反应、催化、DNA辐射损伤、去除挥发性有机空气污染物的修复策略和电离层化学等不同领域。该项目是对直接参与研究的研究生和本科生进行教育和培训的工具。马布斯教授将一些研究结果整合到他的正式化学课程中。阴离子的亚稳态、激发态表示自由电子与中性分子强烈相互作用。该项目利用高分辨率速度映射光电子成像和可调谐光激发来探测这些状态中的振动耦合。记录了小分子阴离子的振动分辨光剥离光谱。激发到亚稳激发态的单个（ro）振动能级之后，通过中性分子的一个（ro）振动能级失去电子。振动通道横截面的光子能量依赖性代表了受激阴离子自脱离（非）振动状态的作用谱，揭示了阴离子中哪些振动水平是强耦合的。作用谱也产生了激发阴离子内部状态的能量，因此为高度相关和开壳、多余电子种的计算提供了有价值的基准。

Under this project, funded by the Chemical Structure, Dynamics and Mechanisms - A (CSDM-A) Program of the Chemistry Division, Professor Richard Mabbs of Washington University in St. Louis is studying what happens when molecules collide with electrons and temporarily capture them. The Mabbs research group is particularly interested in how molecules vibrate and rotate during the electron capture process. The results are particularly important for a full understanding of the electron transfer/collision induced chemistry which occurs in areas as diverse as chemical reactions, catalysis, radiation damage in DNA, remediation strategies for removing volatile organic air pollutants, and ionospheric chemistry. This project serves as a vehicle for the education and training of graduate students and undergraduate students who are directly involved in the research. Professor Mabbs integrates some of the results of the research into his formal chemistry courses.Metastable, excited electronic states of anions represent free electrons interacting strongly with a neutral molecule. This project probes vibronic coupling within such states using high resolution velocity mapped photoelectron imaging and tunable photoexcitation. Vibrationally resolved photodetachment spectra of small molecular anions are recorded. Excitation to individual (ro)vibrational levels of a metastable excited anion state is followed by electron loss via one of the (ro)vibrational levels of the neutral molecule. The photon energy dependence of a vibrational channel cross section represents an action spectrum for autodetachment from a (ro)vibronic state of the excited anion, revealing which vibrational levels are strongly coupled in the anion. The action spectra also yield the energies of internal states of the excited anion and therefore provide valuable benchmarks for state-of-the art calculations of highly correlated and open shell, excess electron species.