Pinning of size-selected Pd nanoclusters on graphite

The production of stable cluster arrays on smooth surfaces has several potential technological applications. We report a study of the pinning of size-selected palladium nanoclusters on the graphite surface. The clusters formed during gas aggregation in vacuum are projected with sufficient kinetic energy to create a defect in the graphite surface. The energy necessary to create such an immobilizing defect is investigated as a function of the palladium cluster size. The palladium pinning energy is found to deviate from the simple binary collision model as appropriate to previously reported silver and gold results. This finding is in agreement with the deviation of nickel clusters and points to the influence of the interatomic cluster bonding on the mechanics of the collision.