M 4–M 5N 45 Coster–Kronig transition in metallic Pd

Abstract

From an analysis of the M 45 X-ray photoelectron spectroscopy (XPS) spectrum and the singles M 45–N 45N 45 Auger-electron spectroscopy (AES) spectrum of Pd metal, it has been known that the M 4–M 5N 45 Coster–Kronig (CK) transition is energetically disallowed in Pd metal. However, the M 45–N 45N 45 Auger-photoelectron coincidence spectroscopy (APECS) spectrum measured in coincidence with the M 4 photoelectron line shows that the M 4–M 5N 45 CK transition is not significantly quenched in metallic Pd. The present analysis of the APECS spectrum using a many-body theory shows that the N 45 hole created by the CK transition is delocalized before the M 5 hole decays. Thus, the M 4–M 5N 45–N 45N 45N 45 CK transition preceded Auger transitions should be interpreted as the M 4–M 5–N 45N 45 transition. The CK transition rate of metallic Pd is as large as 0.32 eV, comparable to that in Rh.