Photoelectron diffraction at low energies: the applicability of single scattering calculations

Abstract

The energy dependence of the 4f core level photoemission intensity from Ta(100) has been modeled at low electron kinetic energies using the single scattering cluster (SSC) approximation. The results show a strikingly similar shape to that of a full multiple scattering calculation, particular at electron kinetic energies less than 75 eV. A comparison with the experimentally measured surface/bulk core level intensity oscillations indicates that the first interlayer spacing of the Ta(100) surface is contracted by 11 ± 3%, consistent with previous determinations. These results suggest that SSC calculations can model low energy photoelectron diffraction data from surface shifted core levels with sufficient accuracy to enable a quantitative structural determination of clean, unreconstructed surfaces.