High-resolution helium-atom scattering experiments were performed on epitaxially grown layers of KBr on a RbCl(001) 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 single-phonon inelastic scattering were carried out on each succeeding layer to determine the surface-phonon dispersion in both the ΓM and ΓX 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. © 1996 The American Physical Society.

• Received 8 December 1995

DOI:https://doi.org/10.1103/PhysRevB.53.13891