Resonant Photoemission vs. Coster-Kronig Auger Decay At the L III Thresholds of Ni Metal and CuO

We report on a resonant photoemission study of Ni metal and CuO at the L III soft-X-ray absorption thresholds. The valence band spectra exhibit a strong enhancement of electron emission at resonance, which is shown to be mostly due to an incoherent superposition of a photoemission signal with a more intense signal from L 3 M 4,5 M 4,5 Coster-Kronig decay of the core-ionized state. The resonant enhancement of the valence band photoemission satellite amounts to a factor of ≃12, far short of the recent claim of a giant resonance. Implications of these results with respect to the nature of the 3 d states in these materials are briefly discussed.