Elastic photoelectron-scattering effects in quantitative X-ray photoelectron spectroscopy

We present improved formulae for the correction parameters Qx and βeff that are used to account for elastic scattering of photoelectrons in quantitative X-ray photoelectron spectroscopy (XPS). The new formulae are based on new Monte Carlo simulations for 584 photoelectrons in 39 elemental solids that could be excited by Mg Kα and Al Kα X-rays in 315 different XPS configurations. The new simulations differed from similar earlier calculations in that differential elastic-scattering cross sections calculated from the Dirac–Hartree–Fock potential were utilized rather than those from the Thomas–Fermi–Dirac potential, a smaller analyzer acceptance angle was chosen, and the number of trajectories in each simulation was an order of magnitude larger. New values of Qx and βeff were obtained for each photoelectron line, each X-ray source, and each XPS configuration. These Qx and βeff values could be fitted to simple two-parameter expressions, each a function of the single-scattering albedo and the photoelectron emission angle. Values of Qx from the new predictive formula differed from the previous expression by less than 1%. Larger deviations in the values of βeff, up to 2.5%, were found from the new fit to the βeff parameter. The new expressions for Qx and βeff provide a convenient means for correction of elastic-scattering effects in XPS.