Prof. Fleming Crim, University of Wisconsin-Madison

Controlling Reactions and Watching Energy Flow in Gases and Liquids

Vibrational energy plays a crucial role in chemical reactions since the relative motion of the constituent atoms transforms molecules from reactants into products. Thus, one means of controlling the course of a reaction is selective excitation of vibrations containing a significant component of motion along the reaction coordinate. Experiments on both bimolecular reaction and photodissociation of vibrationally excited molecules demonstrate this possibility by selectively breaking chemical bonds.

These measurements raise the possibility of similar manipulations in liquids. Experiments using ultrashort laser pulses to prepare a bond vibration and to monitor the vibrationally excited molecule directly observe the flow of vibrational energy in isolated molecules and in molecules in solution. They reveal the influence that level of initial vibrational excitation, the vibrational state structure of the excited molecule, and the identity of the solvent on the flow of energy within the excited molecule and into the solvent. The rates of these processes determine the characteristic times for control of bimolecular reaction or photodissociation in liquids.

For more information contact Dr. Christine Payne (404-385-3125).