Electron-Molecule Temporary States: Vibronic Coupling in Excited Anions

电子-分子临时态：激发阴离子中的电子振动耦合

• 批准号: 1566157
• 负责人: Richard Mabbs
• 金额: $ 44万
• 依托单位: Washington University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-09-01 至 2020-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1566157&HistoricalAwards=false
• 关键词: Electron; Molecule; Temporary; States; Vibronic

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.

在这个由化学系化学结构、动力学和机制(CSDM-A)计划资助的项目下，圣路易斯华盛顿大学的理查德·马布斯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研究小组对电子捕获过程中分子如何振动和旋转特别感兴趣。这些结果对于全面理解电子转移/碰撞诱导的化学特别重要，这种化学发生在各种领域，如化学反应、催化、DNA辐射损伤、消除挥发性有机空气污染物的补救策略和电离层化学。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。Mabbs教授将一些研究结果整合到他的正式化学课程中。阴离子的亚稳定、激发电子态代表自由电子与中性分子强烈相互作用。这个项目使用高分辨率的速度映射光电子成像和可调谐的光激发来探测这种状态下的振动耦合。记录了小分子阴离子的振动分辨光剥离光谱。激发到亚稳态激发阴离子态的单个(Ro)振动能级之后，电子通过中性分子的一个(Ro)振动能级损失。振动通道截面的光子能量依赖关系代表了从激发阴离子的(Ro)振动态自脱离的作用谱，揭示了阴离子中哪些振动能级是强烈耦合的。作用光谱还产生了激发负离子的内态能量，因此为高度关联和开放壳层的过剩电子物种的最新计算提供了有价值的基准。