Surface lattice dynamics of KBr epitaxially grown on RbCl(0 0 1)

Abstract High resolution He atom scattering experiments were performed on epitaxially grown layers of KBr on a RbCl(0 0 1) substrate for coverages of one, two, and three monolayers. The in situ growth of the KBr was monitored by following the intensity of the specularly scattered He beam versus coverage. The inelastic scattering was measured for each deposited layer to determine the surface phonon dispersion curves as a function of coverage in both the Γ M ¯ and Γ X ¯ high symmetry directions of the surface Brillouin zone. Fits to the data from the KBr/RbCl system, which is nearly perfectly lattice matched, were obtained from a shell model calculation whose parameters are found to provide not only a good match to the measured dynamics of these deposited films, but in addition, to the dispersion of bulk and clean surfaces of KBr, RbCl, KCl, and RbBr.