The theory of the anomalous skin effect in metals for obliquely incident radiation

Abstract

The problem of the anomalous skin effect in metals is studied theoretically for the case of obliquely incident radiation. It is shown that at upper visible and ultra-violet frequencies, the effective surface impedance of a metal varies with the direction of polarization of the incident radiation. Differences are of the same order of magnitude as terms arising from the displacement current. As a result, formulae for refractive indices, reflectivities and the principal angles at oblique incidence must be rederived in terms oftwo surface impedances. By a generalization of Dingle’s method, expressions are obtained for the optical constants which are valid for all angles of incidence and for frequencies not lying within internal photoelectric absorption bands. Experimental results for the principal azimuth for silver are shown to be in closer agreement with the present theory than with either the Drude-Kronig theory or the theory of the anomalous skin effect assuming a single impedance. Suggestions are made to guide future experimental work in metal optics.