Creation of binary van der Waals clusters by pickup

Molecular-dynamics simulations have been performed to investigate the dynamical processes occurring during and after the “pickup” of Kr and Xe atoms by Ar₂₁₆ and Ar₁₀₀₄ clusters under “quasiexperimental” conditions. We show that matrix states are the most probable final locations for both Kr and Xe atoms. Under our experimental conditions, we find both dopants restricted to a shell relatively close to the cluster surface so that we have to exclude the creation of pure core matrix states. Due to their very different interatomic distances and potential well depths, Kr pickup normally leads to nearly perfectly structured fcc mixed clusters with the dopants in substitution positions while Xe pickup results in clusters with large amorphous, glasslike domains. We show that those results are very well suited to interpret recent experimental observations concerning the surface scattering of binary van der Waals clusters prepared by the pickup technique.