Theoretical studies of the angular distributions of oxygen atoms ejected from an ion bombarded c(2×2) overlayer of oxygen on Ni(001). I. Effect of geometry

A detailed molecular dynamics study has been performed in order to determine the factors controlling the ejection directions of adsorbate atoms due to 600 eV Ar+ ion bombardment. The specific system studied is oxygen which dissociatively adsorbs to form a c(2×2) overlayer on Ni(001). A fourfold bridge, an atop or linear and twofold bridge bond, as well as several heights of the oxygen atoms above the surface were investigated. The angular distributions are shown to be influenced by both the bonding site and the height of the oxygen adsorbate. There are distinguishing characteristics that can be ascribed to each of these three bonding sites.