Charles Harris is supported by a grant from the Theoretical and Computational Chemistry Program to continue his research in femtosecond studies of chemical reaction dynamics in simple liquids. Two main lines of research will be pursued. The first line of research involves the investigation of solute/solvent interactions of polyatomic molecules in solution using femtosecond and picosecond infrared and visible laser experiments as well as molecular dynamics simulations. This work will extend the work already completed on iodine in liquid krypton and xenon to diatomic molecules such as diatomic iodine anion, iodine chloride and iodine bromide in liquid krypton and xenon. Infrared pump and probe techniques will also be used to examine carbon-hydrogen stretching mode relaxation times of simple polyatomic as a function of pressure in krypton and xenon solvents. The second area of study involves the use of femtosecond and picosecond infrared and visible spectroscopic techniques to study reaction mechanisms of several organometallic compounds whose branching ratios and quantum yields are controlled by the ultrafast energy transfer between solute and solvent. These studies will encompass a broad range of mechanistic studies, including carbon-hydrogen and silicon-hydrogen bond activation in transition metal compounds and photochemical ring slippage of an aromatic ligand. Since many commercially important chemical reactions take place in solvents, it is important to understand the influence that such solvents have on the reaction dynamics. A number of effects, such as solvent cage effects, vibrational relaxation and quantum mechanical tunneling, that are not present in the gas phase, completely dominate condensed phase chemical reactions. It is important to develop reliable theories for model chemical systems that can then be applied to improving the efficiency of commercially important chemical reactions. The work that is being performed by Harris provides an important experimental basis for the development of such theories.
