Derivation of new energy-loss functions as applied to analysis of Si 2p XPS spectra

Abstract

New energy-loss functions for Si 2p photoelectrons have been derived from reflection electron energy-loss spectroscopy (REELS) spectra using a Landau formulation modified to account for elastic scattering. These energy-loss functions revealed significant contributions from occupied surface states, as well as from interband transitions in addition to surface and bulk plasmon excitations. They contribute to a broadening of the signal characteristic of the bulk and surface plasmon excitations. Monte Carlo simulation based on the use of the new energy-loss functions appears to describe very well the energy-loss structure in REELS spectra measured under different experimental conditions. These new energy-loss functions have also been effectively applied to background subtraction from X-ray photoelectron spectroscopy (XPS) spectra to derive more precise source functions of Si 2p photoelectrons. These source functions, when applied to two XPS spectra measured under quite different experimental conditions, showed good agreement.