In this project in the Experimental Physical Chemistry Program of the Chemistry Division, Crim will continue studies of the influence of vibrational excitation on the course and rate of bimolecular chemical reactions. The current work will extend the investigations from the gas into the liquid phase in the expectation of demonstrating selective control of the course of a bimolecular reaction by preferentially breaking a chosen bond. In the proposed gas-phase studies visible or infrared photons will excite vibrations of bonds which then react with photolytically created atoms to form products. Measuring the quantum states of the products helps identify the pathways of the reactions accelerated by the vibrational excitation. In favorable cases, one can cleave a bond preferentially. Vibrationally driven bimolecular reactions in liquids and supercritical fluids require ultrafast excitation of reagents and detection of products. Nonlinear light generation will provide the excitation and absorption or coherent Raman scattering will be used for detection. Collaborations with a theoretician will allow tests of dynamical theories and potential energy surface calculations. In this research the outcome of a chemical reaction between a polyatomic molecule and an atom is directly controlled by exciting the molecular vibration of the bond which is expected to break in the course of the reaction. This expectation is based on the fact that the geometry change that occurs in going from reactants to products first requires the stretching of bonds similar to that which occurs during molecular vibrations. The results of this research are expected to have an impact in atmospheric chemistry, combustion, and the understanding of plasmas
