Comparison of x-ray absorption with x-ray photoemission of nickel dihalides and NiO

High-resolution L₂,3 x-ray absorption data are presented for nickel dihalides and nickel oxide. The near-edge multiplet splitting is observed to decrease rapidly with decreasing anion electronegativity. This decrease is accompanied by an increase in a satellite feature. A detailed analysis of the data in terms of recently proposed many-body theories is presented and is shown to yield excellent agreement with experiment allowing a determination of the charge-transfer energy, the d-d Coulomb interaction, and the Ni d-anion p hybridization interaction. We show that the values obtained are in good agreement with those obtained from x-ray photoelectron spectroscopy even though the spectral shapes are strongly different. The difference in spectral shapes is shown to be due to the very different final states.