Surface plasmons in solids

Some of the properties of surface plasmons in nearly-free-electron solids are reviewed. Experiment and theory bearing on the dispersion and damping of such excitations in some simple geometries will be discussed. Coupling with the radiation field may modify both of these properties. The surface plasmon may be regarded as the source of the image force at an external charge and of dispersion forces between solids. Some consequences of coupling between plasmon modes through spatial nonuniformities or spatial deviations in the linear response function of a solid are considered briefly.