Knowledge Bank

Recently, experimental studies of the vibrationally mediated photodissociation of $H2O$ in $Ar-H2O$ 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 $H2O$ at the same photolysis $wavelengths.a$ Much warmer OH rotational distributions were obtained from photolysis of the $Ar-H2O$ clusters. In order to understand the physical origins of these results we have simulated the photodissociation of $H2O$ and $Ar-H2O$ 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.