ELECTRONIC EXCITATIONS ON SILVER SINGLE-CRYSTAL SURFACES

Recent results are presented of surface electronic excitations on Ag s ingle crystals. For small q(parallel-to) the data show a linear and Po sitive dispersion of the surface plasmon for all faces, whose slope de pends on crystallographic face, and a strong azimuthal anisotropy in c ase of Ag(110). This demonstrates that the centroid of the induced cha rge for frequencies equal to the surface plasmon frequency is placed i nside the surface. Different mechanisms determine surface plasmon damp ing. Face dependence is caused by the presence of face specific surfac e states. The dependence on crystal temperature is discussed.