An In-depth Theoretical Study of Ligand Field and Charge Transfer Effects on Co2p2+ L2,3 edges X-ray Absorption Spectra

The 2p L-2,L-3 -edges X-ray absorption spectrum of Co2+ in octahedral (O-h) symmetric ligand field is studied theoretically via the multiplet calculation method. The octahedral symmetric crystal field and corresponding charge transfer effect between ligands and Co2+ cation have been investigated. All the parameters used in the multiplet calculation are discussed systematically in regards to their specific effect on X-ray absorption features and related mechanisms. The calculated results are compared with the L-edge X-ray absorption spectra of CoO and CoCl2 both with the same O-h symmetrical local structure of the Co2+ cation. The experimentally observed multiplet spectra features are assigned to different spin states and their intensity change is related to the crystal field strength. The underlying charge transfer effect has also been revealed. This study provides a fundamental basis for multiplet calculations of complex systems with lower symmetry associated with cobalt and other transition metals.

Automated summary

This study theoretically investigates the X-ray absorption spectrum of Co2+ in an octahedral symmetric ligand field using multiplet calculation method. It discusses the impact of crystal field and charge transfer effect on X-ray absorption features, and compares the results with CoO and CoCl2 with the same O-h symmetrical local structure. The experimentally observed multiplet spectra features are assigned to different spin states and related to crystal field strength, revealing the charge transfer effect.