15min:

FENG CHEN AND ANNE B. MCCOY, Department of Chemistry, The Ohio State University, Columbus, OH 43210.

Recently, experimental studies of the vibrationally mediated photodissociation of \chemH₂O in \chemAr-H₂O van der Waal complexes have been reported. In these studies, the OH rotational distributions were measured and compared with the ones that resulted from the photodissociation of \chemH₂O at the same photolysis wavelengths.\footnoteVotava, O.; Plusquellic, D. F.; Myers, T. L.; Nesbitt, D. J. J. Chem. Phys. \underline112, 7449 (2002). Much warmer OH rotational distributions were obtained from photolysis of the \chemAr-H₂O clusters. In order to understand the physical origins of these results we have simulated the photodissociation of \chemH₂O and \chemAr-H₂O using a multiple configuration mixed quantum/classical approach. By comparing the rotational distribution of the OH products that are obtained from photodissociation of the complexed and uncomplexed water molecules, we find that the Ar atom has a strong effect on the rotational distribution of the OH fragment in intracluster collisions. The simulations provide insights to the dynamics of photodissociation in clusters.