Thin epitaxial AgBr(001) films grown on NaCl: Growth, surface structure, and phonon dynamics

Thin AgBr(001) films of up to 100 monolayers thickness epitaxially grown on the NaCl(001) single-crystal surface have been investigated with high-resolution elastic and inelastic helium-atom scattering. Diffraction experiments were used to optimize the film growth conditions to assure a microscopically well-ordered AgBr(001) surface under UHV conditions and provided information on the symmetry of the surface unit cell, surface corrugation amplitude, thermal expansion coefficient, and the surface Debye temperature. From time-of-flight spectra the dispersion curves of the surface Rayleigh mode, the longitudinal acoustic, an optical and a crossing mode were measured out to the Brillouin-zone boundary in the two crystallographic directions [100] and [110]. [S0163-1829(99)00323-9].