Helium scattering measurements of the Ag(111) surface phonon dispersion

Abstract

Energy and intensity measurements have been performed on 23 meV He atoms scattered from 135 K Ag(111) to yield information on the surface dispersion relation. The preliminary results are in qualitative agreement with the linear Rayleigh phonon dispersion curve expected from continuum theory and experiment. The scattering probability falls exponentially with increasing phonon frequency but shows a distinct maximum at an angle dependent on incident beam angle and energy.