PRODUCT STATE DISTRIBUTION IN THE PHOTODISSOCIATION OF VINYL-CHLORIDE AT 193 NM

The rotational state populations of HCl(upsilon" = 0, 1, and 2) and the fine structure population of Cl(2P(j)) produced in the UV photodissociation of vinyl chloride were measured in a molecular beam pump-and-probe experiment. Boltzmann-like distributions were observed for the rotational populations in vibrational states upsilon" = 1 and 2, with temperatures of 2100 +/- 250 and 1800 +/- 140 K, respectively. In contrast, for upsilon" = 0 a non-Boltzmann distribution was observed, with low- and high-J "temperatures" of 340 and 22600 K, respectively. The very different rotational distributions observed for upsilon" = 0 and upsilon" > 0 suggest the existence of a dual mechanism for elimination. 89% of the Cl atoms were observed in the 2P3/2 state, which is indicative of an adiabatic recoil mechanism.