Reaction Dynamics of Vibrationally Excited Molecules in Gases and Liquids

该项目是对液体和气体中反应的统一研究，目的是比较振动激发对两种环境中双分子反应的影响，并了解环境所起的作用。在气体中，可以使用激光脉冲来促进和控制双分子反应，以产生反应自由基，以振动方式激发反应物，并检测反应产物。同样的概念方法，使用不同的技术，将应用于液体。气相研究依靠相对较高的光谱分辨率激光来制备和探测反应物和产物的单个量子态。由于在液体中频繁相遇，溶液中的研究需要较短的时间分辨率，导致激光脉冲的光谱分辨率较差。然而，通过在激发和询问步骤中明智地选择时间和光谱分辨率来激发和探测液体中的个体振动是可能的。该项目将在振动模式选择性单碰撞反应中使用溴，并将气相反应与溶液中的反应进行比较。溶液相实验中的高时间分辨率将允许直接观察光解生成的溴原子在形成络合物并与振动激发的溶剂分子反应时的演化。对分子束中相同反应的单碰撞研究将提供一个比较点，通过观察振动激发的影响，而不是周围溶剂的复杂程度。该项目的基础科学将为研究生提供宝贵的经验和技能，以及旨在将威斯康星大学/麦迪逊大学的研究、教学和学习结合在一起的机会。首席研究员将参与与教育和政策相关的活动，并与初学者接触有关研究企业的信息。

This project is a unified study of reactions in liquids and gases with the goal of comparing the influence of vibrational excitation on bimolecular reactions in the two settings and of understanding the role played by the surroundings. In gases, bimolecular reactions can be promoted and controlled using laser pulses to generate a reactive radical, to excite a reactant vibrationally, and to detect the reaction products. The same conceptual approach, using different technology, will be applied in liquids. Gas-phase studies rely on relatively high spectral resolution lasers to prepare and probe individual quantum states of the reactants and products. Because of the frequent encounters in liquids, studies in solution need short time resolution, with the consequence that the spectral resolution of the laser pulses is poorer. Nonetheless, it is possible to excite and probe individual vibrations in liquids by a judicious choice of time and spectral resolution in the excitation and interrogation steps. This project will use bromine in vibrational-mode selective single collision reactions and compare gas-phase reactions with those in solution. The high time resolution in the solution-phase experiments will allow the direct observation of the evolution of a photolytically generated bromine atom as it forms complexes and reacts with vibrationally excited solvent molecules. Single collision studies of the same reactions in a molecular beam will provide a point of comparison by observing the influence of vibrational excitation without the complication of the surrounding solvent. The fundamental science in this project will provide valuable experience and skills to graduate students, as well as opportunities designed to integrate research, teaching, and learning at the University of Wisconsin/Madison. The principal investigator will participate in education and policy related activities, and reach out to beginning scientists about the research enterprise.