On the theory of photoemission

Abstract

This paper is concerned with the a priori theory of the photoemission process in solids. Scattering-theoretical and response-theoretical approaches are discussed and a new demonstration of their equivalence is given. The elastic photoemission spectrum is analyzed in detail and an expression exact to all orders in interparticle interaction is obtained. This expression is similar to the renormalized three-current correlation formula used by Pendry and by others but includes also a screening and exchange-correlation correction to the optical field. The loss part of the spectrum is also discussed and a new quantum-mechanical approximation for the energy losses is obtained. For long mean free paths this correctly reduces to a three-step model in which the energy dissipation is given by a semi-classical transport equation. © 1985 IOP Publishing Ltd.