No abstract

High-resolution helium-atom scattering experiments were performed on epitaxially grown layers of KBr on a RbCl͑001͒ substrate for films 1, 2, and 3 ML thick. The layer-by-layer growth was monitored in situ by measuring the intensity of the specularly scattered He beam versus coverage. Measurements of the singlephonon inelastic scattering were carried out on each succeeding layer to determine the surface-phonon dispersion in both the ⌫M and ⌫X high-symmetry directions of the surface Brillouin zone. Shell-model potential parameters were determined in a consistent fashion for the four anion-cation constituents at the interface, which gave a good fit to the dispersion curve data from 1-, 2-, and 3-ML KBr/RbCl epitaxially grown systems as reported in this study and, in addition, the bulk and clean surface dispersions of KBr, RbCl, KCl, and RbBr were fit by the same parameters.