Angular distribution of Rh atoms desorbed from ion-bombarded Rh{100}: Effect of local environment

Energy-resolved angular distributions of Rh atoms desorbed by 5 keV Ar-ion bombardment of the Rh{100} surface are measured with use of a multiphoton resonance ionization technique. The results are shown to be in good agreement with molecular-dynamics simulations of the ion-impact event using the same interaction potential optimized previously to describe desorption from Rh{111}. In addition, by analyzing contour plots of the surface potential energy, the trend in the experimental results for Rh{100} and those previously published for Rh{111} are well explained. Based on this analysis, it is concluded that the peak in the polar-angle distribution of neutral particles desorbed from ion-bombarded single crystals is mainly determined by the relative positions of surface atoms which influence the trajectory of an exiting particle via channeling and blocking. Moreover, the anisotropy of the momentum imparted to the surface atoms in the last collision leads to an enhancement of ejection along certain crystallographic directions.