XPES studies of oxides of second- and third-row transition metals including rare earths

Abstract

X-ray photoelectron spectroscopy has been employed to investigate oxides of second- and third-row transition metals, including those of rare earths. Systematics in the spin-orbit splittings and binding energies of core levels of the metals are described. In most of the cases studied, the dependence of the spin-orbit splittings on the atomic number Z is given by the relation ΔE=a(Z−Z₀)⁴, where a is the quantum defect parameter and Z₀ is the effective screening. Core-level binding energies are found to increase with the oxidation state of the metal. Most of the core-level binding energies are related to the atomic number Z by the expression E=x(Z−Z₀)², giving rise to linear plots of ln E versus ln Z. Specific features of individual oxides, with respect to satellites, multiplet structure, configuration mixing, and other properties are also discussed. The spectra of PrO₂, Pr₆O₁₁, TbO₂ and Tb₄O₇ are reported for the first time.