The shift of L 2 level photoelectron line of Cu metal measured in coincidence with the L 2–L 3V–VVV Auger-electron line

Abstract

The L 2 photoelectron line of Cu metal measured in coincidence with the L 2–L 3V–VVV Auger line, moves to lower kinetic energies when the Auger analyzer moves to lower kinetic energy tail of the L 3–VV ( 1G) Auger line. Creagh et al. [Surf. Sci. 432 (1999) 297] proposed the possibility that the shift is due to the post-collision interaction (PCI). However, the present many-body theory shows that even without the presence of the PCI, the L 2 coincidence-photoelectron line shifts from the XPS spectral peak position towards the lower kinetic energy side, irrespective of the Auger-electron analyzer’s positions. The energy shift depends on the Auger-electron analyzer’s position. The coincidence-photoelectron line is asymmetrical. The present theory predicts the shift which agrees with the observed energy shift. The shift is due to the change in the partial L 2–L 3V CK transition rate which depends critically on the CK-electron energy. We comment on the PCI effect in the light of the recent experimental study of the L 2–L 3V CK transition rate near the L 2 ionization threshold.