Study of gold nanocluster sputtering under 38-keV Au ion bombardment by a classical molecular dynamics method

Abstract

The computer simulation of the interaction of 38-keV Au1 ions with isolated spherical Au N nanoclusters of diameters 2.6 and 18 nm is performed in the framework of the classical molecular dynamics (MD) method. The distribution of the absorbed energy e per one atom of the irradiated cluster and the sputtering yields are analyzed for different ratios of the nanocluster diameter D to the average projective range R p of the bombarding ion. It is established that the small values of the absorbed energy (e ≪ emax = E/N) are most probable for D < R p, and either small (e ≪ emax) or the maximum possible (e ∼ emax) values are mainly realized for D ≤ R p. It is shown that the total sputtering yield depends weakly on the impact parameter. It is demonstrated for the first time that the irradiated cluster, as a whole, can be ejected by direct impact with a probability of approximately 6–13%. Such events are realized in the cases where the bombarding ion causes secondary cluster-atom emission in the dominant direction to a substrate, with the result that an unsputtered cluster fraction acquires momentum in the opposite direction. This recoil effect can be one of the mechanisms for desorption of nanoclusters deposited on the surface under ion (or cluster) bombardment.