Incident beam effects in angle-resolved Auger electron spectroscopy.

Abstract

We have investigated the role of the angle of electron beam incidence in producing anisotropies in angle-resolved Auger electron emission from single crystals. By performing angle-dependent measurements of Pd MNN Auger emission from Pd(001) with two different angles of incidence, we show that the Auger electron angular distributions are independent of incident beam direction. Rather, the observed intensity modulation is the result of Auger electron scattering and interference, as demonstrated by the comparison of experimental angular distributions with those calculated using kinematical scattering theory. In the calculation, it is assumed that atoms in each layer below the surface receive equal incident beam flux for all angular orientations (i.e., no incident beam channeling). Agreement between theory and experiment is good, indicating that although incident beam channeling surely occurs, the enhanced depth of penetration is ineffective at producing Auger electrons which can reach the surface without suffering inelastic scattering.