Theory of 45 degrees reflectometry from metal surfaces

Abstract

The use of optical spectroscopies to study surfaces is hindered by the difficulty of disentangling bulk and surface contributions to the signal. According to Fresnel formulae, the a and p reflectances R of a semi-infinite system obey the simple relation Delta = R-s(2) - R-p = 0 when the incidence angle is 45 degrees. Deviations from this result can be related to microscopic surface contributions to R. In this paper we study theoretically Delta for metal surfaces. For a semi-infinite nat jellium we obtain the contributions to Delta from electronic excitations at the surface. To explore Delta for non-jellium conductors, we apply a 'Swiss cheese' model to different surfaces of Ag.