Focused inelastic resonances in the scattering of He atoms from NaCl(001)

Abstract

High-resolution inelastic He-atom surface scattering experiments have been carried out on an in situ cleaved NaCl(001) crystal surface for the incident wave-vector range of 4.29--6.07 A${\mathrm{\r{}}}^{\mathrm{\ensuremath{-}}1}$ in the 〈110〉 high-symmetry direction to detect the recently predicted effect, the focused inelastic resonance (FIR). The scattering angle for the resonance in the 〈110〉 direction is uniquely predicted based on the reciprocal lattice vector exchanged in the process for the bound state \ensuremath{\Vert}${\mathrm{\ensuremath{\epsilon}}}_{1}$\ensuremath{\Vert}=3.4\ifmmode\pm\else\textpm\fi{}0.1 meV. This value is slightly lower than the 3.7\ifmmode\pm\else\textpm\fi{}0.4 meV value found in the literature. The convincing evidence for the FIR effect comes from a systematic analysis of the angular distributions in combination with an energy analysis based on time-of-flight spectra. \textcopyright{} 1996 The American Physical Society.