Theoretical study of Auger-photoelectron coincidence, Auger-electron, and x-ray emission spectra of Ni metal and related systems

The Auger-photoelectron coincidence spectroscopy (APECS) spectrum is formulated in a one-step model, using the real-time nonequilibrium Green's-function method. The APECS L-23-VV spectra of Ni metal and alloys are analyzed, using a semiempirical configuration interaction (CI) model approach. For Ni metal and alloys, the L-2-L3V Coster-Kronig (CK) decay rate ratios are obtained from the coincidence spectra. The ratio increases upon alloying due to more localized valence holes. The initial shakeoff-preceded L-3 V-VVV transition contributes significantly to the L-2-L3V-VVV APECS spectra of Ni metal and NixFey (x=80%, y =20%) but not for Ni,Fe, (x=y=50%). The shakeoff intensity is most likely shifted towards smaller shakeoff energy in the latter system. The satellite intensity variation in the L-23-VV Auger-electron spectroscopy (AES) and L-23-V x-ray emission spectroscopy (XES) spectra of Cu metal, Cu halides, and Cu oxides (including high T-c superconductors) is explained in terms of the L-2-L-3 V-VVV and L23V-VVV decays and the final-state interaction The initial shakeup state does not relax to the lowest-energy state before the core decay starts. [S0163-1829(98)00643-2].