Nonlocal electromagnetic fields near a metal/vacuum interface

A nonlocal formalism is developed to describe the fields at the surface of an electron gas subjected to an incident electromagnetic wave. The electron gas is confined to a semi-infinite half space by an infinite potential barrier; the positive lattice of ions is taken to be a jellium. The response tensor of the electron gas is separated into contributions from the bulk metal and the surface of the metal. A relationship is found between the tensor elements of the bulk contribution to the response and the Lindhard dielectric functions;Specific attention is given to the physical differences in the fieldsresulting from the semi-classical specular scattering model, aRandom Phase Approximation with self-consistent wave functions,and the fully quantum mechanical infinite barrier model. Thesurface-region fields can be understood in terms of elementaryexcitations of the electron gas. The inverse longitudinal dielectric;function and the energy loss function are discussed. Thepossibility of a collective, longitudinal surface mode is presented;(\u271)DOE Report IS-T-1041. This work was performed under ContractNo. W-7405-eng-82 with the Department of Energy