Ultrafast Studies of Energy Redistribution in Condensed Phase Chemical Reactions

密歇根大学的Roseanne Sension教授由实验物理化学项目资助，进行关于凝聚相化学反应中能量重新分配的实验。这些研究之所以令人感兴趣的原因有两个：首先，了解能量松弛和液体中化学反应之间的相互作用在生物过程中很重要。其次，对反应进行连贯控制的前景将是另一个重要结果。这一建议旨在研究溶液中己三烯、环己二烯和脱氢胆固醇等多原子分子的分子内振动弛豫的速度和程度。然后，PI建议研究热分子和溶剂之间相互作用的性质。这一提议的一个成功成果将是一个用于预测、解释和/或控制溶液中化学反应结果的模型。这项拟议的工作是独一无二的，因为PI在深紫外光中能够产生30fS的脉冲。研究能量在分子中流动的路径和流速提供了直接适用于光合作用和视觉等生物过程的信息。在深紫外光中使用超短激光脉冲使这些研究能够接触到小分子。人们认为，溶液中反应的相干控制的第一个演示将是在小分子中，因为可用于分散能量的路径较少，因此，能量更有可能被驱动到感兴趣的反应(例如，键断裂)。这些基础研究利用了激光脉冲产生的最新进展，使飞秒化学的新领域成为可能。

Professor Roseanne Sension of the University of Michigan is funded by the Experimental Physical Chemistry program to perform experiments on energy redistribution in condensed phase chemical reactions. The reason why these studies are of interest is two-fold: first, understanding the interplay between energy relaxation and chemical reactions in the liquid phase is important in biological processes. Secondly, prospects of coherent control of reactions would be another important outcome. This proposal seeks to study the rate and extent of intramolecular vibrational relaxation in polyatomic molecules such as hexatriene, cyclohexadiene and dehydrocholesterol in solution. The PI then proposes to examine the nature of the interactions between a hot molecule and the solvent. A successful outcome of this proposal would be a model used to predict, interpret and/or control the outcome of chemical reactions in solution. The proposed work is unique because of the PI's ability to produce 30 fs pulses in the deep ultraviolet. Studying the pathways that energy flows through molecules and the flow rates provides information that is directly applicable to biological processes such as photosynthesis and vision. The use of ultrashort laser pulses in the deep ultraviolet makes small molecules accessible to these studies. It is thought that the first demonstrations of coherent control of reactions in solution will be in small molecules, since there are fewer pathways available to disperse the energy and, thus, it is more likely that the energy can be driven to the reaction of interest (bond breaking, for example.) These fundamental studies take advantage of recent advances in laser pulse generation that make possible the new field of femtochemistry.