Photoionization Cross-Sections of the Ground and Excited Valence Electrons of Lanthanoids for the Study of Electronic Structure of Materials by X-ray Photoelectron Spectroscopy and Spectrum Calculation of Cluster Ce₆₃O₂₁₆

Photoionization cross-sections of atomic shells are essential for studying the electronic structure of materials using X-ray photoelectron spectroscopy. In the chemical bonding of lanthanoids with other atoms, electrons from both the ground-state configurations and excited states participate. However, existing tables only include photoionization cross-sections for the ground-state configurations of lanthanoids. In this work, photoionization cross-sections were calculated for both the ground and, for the first time, the excited states of lanthanoid atoms for photon energies of 1253.6 and 1486.6 eV. The calculations were based on relativistic wavefunctions of the self-consistent field obtained using the Dirac–Fock method. The application of these results to experimental X-ray photoelectron spectra of lanthanoid compounds is discussed, exemplified by the experimental spectrum of CeO₂ and the first calculated spectrum of cluster Ce₆₃O₂₁₉.