Cluster-surface impact dissociation of halogen molecules in large inert gas clusters

Molecular dynamics simulations of the dissociation of I₂ embedded in large Ar_n (n = 319, 553) clusters, which impact at high velocities (v = 7-15 km s ^-1) on Pt surfaces, result in information on heterogeneous and homogeneous dissociation mechanisms. A broad distribution of dissociation lifetimes is exhibited, which can be attributed to prompt and retarded heterogeneous dissociation and to prompt, retarded and outbound homogeneous dissociation events. The propagation of a microshock wave within a large cluster can be interrogated by the homogeneous dissociation of a chemical probe, with the velocity of the propagation of the dissociation front being close to the cluster impact velocity.