Ultrafast Studies of Energy Redistribution in Condensed Phase Chemical Reactions

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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.