Vacuum Ultraviolet Studies of Molecular Dynamics

This research grant used tunable vacuum ultraviolet radiation generated by four-wave mixing to probe collisional energy transfer, reactive encounters, and photodissociations. Translation-to-vibrationrotation energy transfer was examined in the H CO system to learn how the extent of transfer depends on the collision energy and to determine the vibrational and rotational distribution of the product. The quenching of S1D by N2 was studied to learn the branching ratio for quenching to each of the 3P0, 3p1 and 3P2 components as well as to determine the rates of equilibration among these components. Photodissociations of OCS, C02, and C3O2 at 157 nm were studied to learn the distribution of energy in the S, 0, and CO products and to investigate vector correlations and velocity distributions of these products. This integrated program of molecular dynamics studies using vacuum ultraviolet radiation has enhanced our knowledge both of the chemical physics of these basic processes and of the interaction of high energy photons with small molecules likely to be found in the upper atmosphere. Molecular dynamics, Lasers, Vacuum ultraviolet.