PHOTODISSOCIATION AND VIBRATIONAL-RELAXATION OF I(2-) IN WATER, ETHANOL, AND ETHANOL-D(1)

We have investigated the photodissociation and vibrational relaxation of I2- in water, ethanol, and ethanol-d1. Internal conversion, geminat e recombination, and vibrational relaxation in the top 70% of the grou nd state potential in water are complete within the time resolution of our apparatus ( < 0. 3 ps). Vibrational relaxation down the remainder of the potential (v less-than-or-equal-to 10) occurs with a time cons tant of almost-equal-to 3 ps, very similar to the value of almost-equa l-to 4 ps previously observed in ethanol. Deuteration of the alcoholic proton in ethanol causes no measurable change in the vibrational rela xation rate at the bottom of the well (3.4 +/- 0.4 ps in ethanol, 4.0 +/- 0.4 ps, ethanol-d1), indicating that the solvent degrees of freedo m involved in accepting the I2- vibrational energy at the bottom of th e well do not involve inertial hydrogenic motions of the hydroxyl grou p. Simple spectral and kinetic modeling is employed to help interpret the data.