On the L 2 photoelectron spectroscopy main line of Cu metal measured in coincidence with the Coster–Kronig preceded Auger decay

Abstract

The present many-body theory shows that the L 2 photoelectron spectroscopy (PES) main line of Cu metal measured in the sudden limit in coincidence with the L 2-L 3M 4,5 Coster–Kronig (CK) preceded Auger decay satellite peak does not show any peak KE shift and asymmetric line shape change compared to the singles (noncoincidence) one. The peak KE shift and asymmetric line shape change between the two PES main lines observed by Creagh et al. [C.A. Creagh, S.M. Thurgate, R.P. Craig, C.P. Lund, Surf. Sci. 412 (1999) 297] are not due to the post-collision interaction (PCI) between a slow CK electron and a fast photoelectron (or a fast Auger electron) they attributed to. The inherent PCI between a slow CK electron and a fast Auger electron in the CK preceded Auger decay final state does not manifest in the coincidence L 2 PES main line of Cu metal, even if there is one. The discrepancies between the two PES main lines are due to the inelastic L 3 photoelectrons collected either in coincidence with the elastic Auger electrons emitted by the L 3-VV Auger decay or in coincidence with the inelastic ones. The inelastic L 3-photoelectron background appropriate, respectively for the singles L 2 PES main line and the coincidence one, should thus be subtracted. It is shown that the inherent PCI between a slow CK electron and a fast Auger electron in the CK preceded Auger decay final state is absent in Fe metal irrespective of photon excitation energy because the M 4,5 hole created by the CK decay delocalizes prior to the L 3-hole decay so that the L 2 photoelectron and the CK electrons are decoupled from the L 3-hole decay.