Multiple-scattering approach to angle-resolved photoemission

Abstract

A Green's-function formulation of angle-resolved ultraviolet photoemission spectroscopy is presented for surfaces with overlayer adsorbed systems. Multiple scatterings of the initial state are included through the use of cluster wave functions solved from a self-consistent $X\ensuremath{\alpha}$ scattered-wave method. The final-state process is expressed in terms of a scattering $T$ matrix which propagates the final-state electron through surface layers of the crystal lattice, in the presence of inelastic damping. It is found that major angular asymmetries in the photoemission intensity profiles arise from multiple scatterings off neighboring ion cores. Our formulation, in the limit of taking a single wave function from a single ion-core, reduces to the photoemission theory of a core level.