A note on calculations of photoelectron partial intensities for energies reaching 4000 eV

A very simple method for determining the photoelectron partial intensities and reduced partial intensities for HAXPES photoelectrons is proposed. For these calculations, it is sufficient to know a formalism expressing the photoelectron signal intensity as a function of the inelastic mean free path. The only computational problem is due to required procedure of multiple numerical differentiation, although one can use published programs for that purpose. The proposed method was designed to photoemission emitted by unpolarized X-rays and for planar samples. A wide range of photoelectron energies was considered: from 500 eV to 4000 eV. Evaluation of accuracy was performed by comparison with partial intensities obtained from accompanying Monte Carlo simulations of photoelectron trajectories in the same analytical conditions. The proposed method was found to provide up to eight partial intensities with reasonable accuracy. Depending on element, photoelectron line, and kinetic energy, the mean percentage deviation varied in the range from 0.95% to 3.11%. Similar agreement was observed in comparisons with published partial intensities obtained from Monte Carlo simulations, and with partial intensities obtained from the database SESSA (NIST Database for the Simulation of Electron Spectra for Surface Analysis, Version 2.1.1).