SCATTERING OF ENERGETIC BEAMS AT GLANCING INCIDENCE FROM CRYSTAL-SURFACES - A MOLECULAR-DYNAMICS SIMULATION

The elastic scattering of keV atomic beams of He and Xe incident at grazing angles to a Cu(111) surface is investigated within a classical molecular dynamics formalism. We find that only the corrugation of the interaction potential in the surface direction perpendicular to the incident beam direction significantly influences the scattering, and then only for incidence of the beam along low index crystallographic directions. This corrugation component leads to rainbow scattering in the out of plane angular distribution. The influence of the thermal motion of the surface atoms is two-fold. The thermal displacement component perpendicular to the surface (and only this component) has a significant influence on the energy and angular straggling of both beams. The thermal velocity significantly influences the energy straggling of light projectiles. We find a positive correlation between energy loss and deflection angle of the beam. We show that surface scattering under grazing incidence conditions of keV atomic beams along high index crystallographic directions on close packed surfaces may indeed be accurately simulated (for a restricted range of incident beam energies and incidence angles) using one-dimensional (planar) potentials.