Structural perfection in physisorbed films: A synchrotron x-ray diffraction study of xenon adsorbed on the Ag(111) surface

Synchrotron X-ray scattering has been used to investigate the structure and growth of xenon films physisorbed on the Ag(111) surface. For growth under quasiequilibrium conditions, the bulk Xe--Xe spacing is reached at monolayer completion and fcc films of thickness = > 220 A are observed. Under kinetic growth conditions, intensity oscillations in the specular reflectivity as a function of time demonstrate nearly layer-by-layer growth. Modeling of the intensity at a fixed coverage allows profiling of the xenon/vacuum interface as well as a direct determination of the film's thickness and layer spacings.