Electronic Excitations on Silver Single Crystal Surfaces

Recent results are presented of surface electronic excitations on Ag single crystals. For small q(parallel-to) the data show a linear and Positive dispersion of the surface plasmon for all faces, whose slope depends on crystallographic face, and a strong azimuthal anisotropy in case of Ag(110). This demonstrates that the centroid of the induced charge for frequencies equal to the surface plasmon frequency is placed inside the surface. Different mechanisms determine surface plasmon damping. Face dependence is caused by the presence of face specific surface states. The dependence on crystal temperature is discussed.