Simulation of desorption of gold nanoclusters deposited on the (111) surface of Al and Au under bombardment with Au1 ions and Au400 clusters using the classical molecular dynamics method

Abstract

The mechanisms of desorption of gold nanoclusters deposited on a substrate under low-energy bombardment with ions and clusters (in the mode of elastic stopping predominance) are analyzed. The classical molecular dynamics method is employed for computer simulation of both “direct” and “indirect” impact of bombarding particles (that is, when a projectile particle either directly interacts with the deposited cluster or penetrates into the substrate without hitting the cluster). Au1 ions and Au400 clusters with an energy of 38 keV and 0.18 keV/atom, respectively, are used as projectile particles. The spherical Au6051 gold nanocluster deposited on a substrate of Al(111) or Au(111) is applied as a target. It is shown that indirect impact does not lead to desorption of the nanocluster from the Al substrate in all considered cases; however, it can initiate desorption from the Au substrate. This phenomenon is quite efficient when the heat spike appearing upon penetration of a projectile particle involves the region of contact between the substrate and the nanocluster deposited on it. As this takes place, an intense flow of the sputtered substrate material transfers a sufficient-for-ejection momentum to the deposited nanocluster.