Theory of surface-enhanced Raman scattering from molecules adsorbed at metal surfaces

Abstract

A general many-body formulation of surface-enhanced Raman scattering from admolecules is presented. Both local-field as well as chemisorption effects are taken into account. The theory can be applied to an arbitrary nonstatistical surface. It is shown that the calculation of the cross section can essentially be reduced to (a) the calculation of the classical Green's function for the electromagnetic field in the presence of the bounded metal but without the admolecule and (b) the inversion of "small" matrices. In order to illustrate the general theory, the cross section is worked out for a Newns-Anderson model of chemisorption using a plane metal surface with and without a weak grating and with the plasmon-pole approximation for the dielectric function of the metal. The enhancements of the cross section due to local-field effects, chemisorption, and grating are calculated using available or estimated values for the electronic matrix elements.