Dynamical LEED study of graphite (0001){symbol}-(a{symbol}s3xa{symbol}s3)R30A deg -Xe

Graphite has long been a prototypical substrate for physical adsorption. In light of recent experiments that indicate that Xe and other rare gases generally occupy low-coordination sites on metals, dynamical low-energy electron diffraction (LEED) was used to determine the adsorption geometry for Xe on graphite. Natural single crystals of graphite were used in these studies, and the clean graphite (0001) surface structure was found to be the same as the bulk structure. The adsorption geometry of Xe was studied for the commensurate (surd 3xsurd 3)R30r structure. Unlike Xe adsorbed on metal surfaces, Xe on graphite was found to occupy the high-coordination hollow sites of the honeycomb substrate at a distance of 3.59 pm 0.04 Aabove the graphite plane. The vibration amplitude of the Xe atom was deduced from the fitted Debye temperature to be 0.12 Awhich corresponds well with the measured perpendicular vibration frequency for Xe on graphite.