CAREER: Femtosecond Time Resolution in Electron Collision Initiated Reactions

该奖项由化学系实验物理化学项目资助，将支持华盛顿大学的Richard Mabbs教授及其研究生和本科生研究解离电子附着(DEA)的分子动力学。这项拟议的工作将把目前分子水平的超快时间分辨实验能力扩展到电子碰撞诱导的反应。基于团簇阴离子产生和超快激光询问的新组合技术将被开发出来，以跟踪光致电子附着瞬间的原子运动。时间分辨光电子成像光谱学将跟踪产生的瞬时阴离子物种向稳定产物阴离子的演化，直接沿着反应坐标探测势能面。最初的实验重点将是简单的甲基卤化物系统，但以后的工作将扩展到更大的分子。实验结果的解释将得到从头算电子结构计算和定性/半定量模型的支持。这一职业奖项的教育部分将把高度可视化的光电子成像结果纳入课程。这些图像使用定性模型进行了直观的解释，从而提供了量子概念的具体例证。DEA是一种广泛存在的现象，在各种领域都很重要，如DNA的电离辐射损伤机制、空气污染物的等离子体修复、星际化学和地球化学-S电离层。直接研究DEA的基本细节将允许测试和改进当前的理论处理方法，并导致涉及这些过程的机制的更准确的预测/解释模型。这项研究计划强烈鼓励各级本科生的积极参与。参与这些活动的本科生将发展解决问题的能力、分析能力和批判性思维能力，并将培养对物理科学的长期兴趣。

This award, funded by the Experimental Physical Chemistry Program of the Division of Chemistry will support Professor Richard Mabbs of Washington University and his graduate and undergraduate students in their studies of the molecular dynamics of dissociative electron attachment (DEA). The proposed work will extend current molecular level, ultra-fast time-resolved experimental capability to electron collision induced reactions. Techniques based on a novel combination of cluster anion production and ultra-fast laser interrogation will be developed to follow the atomic motions at the instant of the photo-induced electron attachment. Time-resolved photoelectron imaging spectroscopy will follow the evolution of the produced transient anionic species into stable product anions, directly probing the potential energy surface along the reaction coordinate. The initial experimental focus will be on simple methyl halide systems, but later work will extend to larger molecules. The interpretation of experimental results will be supported by ab initio electronic structure calculations and qualitative/semi-quantitative models. The educational component of this CAREER award will incorporate highly visual photoelectron imaging results into the curriculum. The images are intuitively explained using qualitative models, thus providing concrete illustrations of quantum concepts.DEA is a widespread phenomenon important in such diverse areas as the mechanism of ionizing radiation damage of DNA, plasma remediation of pollutants from air streams, interstellar chemistry and the chemistry of the earth?s ionosphere. Direct study of the fundamental details of DEA will allow testing and refinement of current theoretical treatments and lead to more accurate predictive/interpretive models of mechanisms involving these processes. The active involvement of undergraduate students at all levels is strongly encouraged in this research program. Undergraduates involved in these activities will develop problem solving abilities, analytical skills, critical thinking skills and will develop a long term interest in the physical sciences.