Dispersion relations and sum rules for the normal reflectance of conductors and insulators

Abstract

A systematic derivation of sum rules satisfied by the normal reflectivity and phase of conductors and insulators is presented. The derivation of the dispersion relations for the generalized reflectivity is investigated, and some special features of these relationships are noted. The reflectivity at complex frequencies is examined, and this leads to a simple sum rule for testing theoretical models of reflectance data.