Femtosecond studies of the influence of solvent on chemical reaction dynamics

该奖项由化学系实验物理化学项目资助，南加州大学的Stephen Bradforth教授和研究生将继续研究液体介质对光解离的影响，探索光引发双分子反应的新途径，并开发可以探测液体表面反应的非线性光学光谱技术。光解离研究将集中在溶剂对ICN，BrCN和H2 O2等分子解离的影响，特别是解离过程中产生的双原子碎片（CN和OH）的飞秒时间尺度旋转弛豫。比较实验数据与分子动力学模拟将有助于评估溶剂对弛豫动力学的影响。光引发双分子反应的研究将涉及光生成OH自由基（从OH-或H2 O2）和观察它们与Cl-和Br-在飞秒制度的反应。这些自由基-离子反应在大气化学中作为对流层Cl 2和Br 2形成的可能途径而引起了人们的兴趣。 二阶非线性光学技术，它可以提供表面特定的信息，将被开发，以探索在液体或气溶胶颗粒表面的反应动力学。虽然最初的重点将放在光分离电子的溶剂化和迁移率上，但这些技术最终可能适用于海洋喷雾气溶胶的卤素形成反应的研究。除了通过出版物、会议和研讨会介绍广泛传播研究结果外，Bradforth教授还将通过他的小组网站提供仪器的重要创新，这些创新可能对其他小组的工作有用。超快动力学

In this award, funded by the Experimental Physical Chemistry program of the Chemistry Division, Professor Stephen Bradforth of the University of Southern California and graduate students will continue their investigation of liquid medium effects on photo-dissociation, explore new avenues in photo-initiated bimolecular reactions, and develop nonlinear optical spectroscopic techniques that can probe reactions at liquid surfaces. The photo-dissociation studies will focus on solvent effects on the dissociation of molecules such as ICN, BrCN and H2O2, and especially subsequent femtosecond time scale rotational relaxation of the diatomic fragments (CN and OH) produced in the dissociation. Comparison of experimental data with molecular dynamics simulations will aid in the evaluation of solvent effects on relaxation dynamics. The study of photo-initiated bimolecular reactions will involve photo-generation of OH radicals (from OH- or H2O2) and observation of their reaction with Cl- and Br- in the femtosecond regime. These radical-ion reactions are of emerging interest in atmospheric chemistry as possible routes to the formation of tropospheric Cl2 and Br2. Second order nonlinear optical techniques, which can provide surface-specific information, will be developed in order to explore reaction dynamics at liquid or aerosol particle surfaces. While the initial focus will be on solvation and mobility of photo-detached electrons, these techniques may eventually be applicable to the study of halogen formation reactions on sea-spray aerosols.In addition to the broad dissemination of research results through publications, conference and seminar presentations, Prof. Bradforth will also make available via his group website important innovations in instrumentation that may be useful to other groups working in ultrafast dynamics.