Theoretical Analysis of Multiple Scattering Effects in Angle-Resolved UPS

Abstract

Angle-resolved ultra-violet photoelectron spectroscopy (ARUPS) has been studied using a multiple scattering theory. ARUPS spectra of adsorbed large molecules on surface have information of geometric and electronic structures for near neighbors of an excited molecule. In order to obtain useful information, analyses of scattering order are discussed in terms of real-space multiple scattering theory. The theory allows us to discuss geometric and electronic structures of the excited molecule and local structure of near-neighbor molecules. In this paper, we have studied ARUPS of copper phthalocyanine. The single-scattering calculations are enough to estimate main structures of the spectra. However, the single scattering results are not converged to infinite order multiple scattering results. Our scattering order analysis shows double-scattering processes are important to approximate the infinite-order multiple scattering results. Moreover, we also find that the results of double scattering processes including intermolecular scattering path improve the data of single scattering. If we want to discuss fine structures of ARUPS, we should consider higher order multiple scattering processes.