Directional elastic peak electron spectroscopy in the investigation of order–disorder transition in the Cu 3Au(0 0 1) surface layer: Measurements and SSC calculations

Abstract

We present the results of directional elastic peak electron spectroscopy (DEPES) application to investigating the order–disorder transition in the surface layer of the Cu 3Au(0 0 1) crystal. We measured the DEPES polar profiles for a few sample temperatures ranging from 300 to 1000 K and for a few electron energies ranging from 1000 to 2000 eV. The obtained results were compared with those calculated in the single scattering cluster (SSC) approximation for Cu 3Au(0 0 1) clusters characterized by different inelastic mean free paths of electrons, effective Debye temperatures and surface layer atomic structure (including ordering and rippling of gold atoms). Measured and calculated DEPES profiles were found to be sensitive to the order–disorder transition. Reasonable agreement between measurements and calculations was obtained for the effective Debye temperature equal to ( 220 ± 6 ) and ( 172 ± 4 ) K for T < T C and T > T C , respectively, and for the rippling of Au atoms in the first atomic layer decreasing during the order–disorder transition from 0.12 to 0.09 Å.