Single-Rayleigh-Phonon Interaction in the Scattering of He from LiF(001)

Abstract

Energy analysis has been performed on 63-meV He atoms scattered from 135\ifmmode^\circ\else\textdegree\fi{}K LiF(001) along the $〈010〉$ direction. The results suggest that single Rayleigh phonons dominate the interaction near specular scattering. Points on the dispersion curve are determined uniquely and suggest a limiting speed of sound of (4.2 \ifmmode\pm\else\textpm\fi{} 0.5) \ifmmode\times\else\texttimes\fi{} ${10}^{5}$ cm/sec.