Recent developments in the theory of angular distribution and spin polarization of Auger electrons

Abstract

The general theory of angular distribution and spin polarization of Auger electrons is reviewed. The angular distribution of open-shell atoms is investigated in more detail. Whereas the KLL Auger lines have to be isotropic for closed-shell atoms, this is no longer valid for open-shell systems. The angular distribution of the KLL spectra of sodium and laser-excited sodium is discussed. Large anisotropy parameters are predicted for the unresolved initial- and final-state multiplets of the laser-excited sodium KLL spectrum. An outlook is given for the angular distribution of Auger electrons emitted from diatomic molecules. The case of electron-impact ionization is discussed. The physical importance of a coherent excitation process is emphasized within a simple example. For the case of the rare gases a simpler experiment is discussed to measure the in-reaction plane components of the spin-polarization vector. Within the LS-coupling approximation theoretical predictions for the spin-polarization vector for Auger transitions on argon are given. A degree of spin polarization of up to 50% is predicted.