Surface and bulk phonon‐assisted resonances with surface bound states in the inelastic scattering of He atoms on NaCl (001)

Abstract

High‐resolution He atom scattering experiments have been carried out on the NaCl (001) surface in both the 〈100〉 and 〈110〉 surface high symmetry directions. Time‐of‐flight (TOF) arrival spectra of the inelastically scattered He atoms were analyzed to obtain the surface phonon dispersion curves. Several of the TOF peaks corresponding to Rayleigh mode phonons were found to have relatively large intensities and there appeared to be a number of well‐resolved peaks in the time‐of‐flight which did not correspond to surface‐localized modes when the data were compared with previous calculations for NaCl. These data appear to be associated with surface and bulk phonon‐assisted resonances with surface bound states. Analysis of these resonances yields results consistent with the four bound states of He on NaCl (001) which had been previously reported.