a Department of Physics, Indiana University, Bloomington, Indiana 47405, USA
b Department of Physics, Sook-Myung Womens University, Seoul 140–172, South Korea
Abstract:
High-resolution electron energy loss spectroscopy is used to study surface phonons in the direction of qG on Ag(111). The gap mode (S2) at in the surface Brillouin zone is measured for the first time. We have also measured the Rayleigh mode and the resonance mode up to the zone boundary. The results are complementary to the earlier He atom scattering measurements and are in good agreement with the first-principles calculations performed recently.