STRONGLY Z-DEPENDENT AUGER AND PHOTOELECTRON DIFFRACTION IN MGO(001)

We have measured angular distributions of Mg KL2,3L2,3 Auger and O 1s core-level photoemission intensities at high angular resolution for MgO(001). We find substantial differences in the two types of scans over many regions of k space, despite the very similar local structure of Mg and O in the rocksalt lattice. These diffraction scans are quantitatively predicted by spherical-wave, single-scattering theory, assuming an s wave for the Mg KL2,3L2,3 Auger transition' The differences that are observed between Mg KL2,3L2,3 Auger and O 1s diffraction scans are shown to be due purely to differences in the elastic scattering phase shifts for Mg and O atoms in the solid.