The 2p absorption spectra of 3d transition metal compounds in tetrahedral and octahedral symmetry

The authors present the 2p (L_2,3) absorption spectra of first-row transition metal ions in tetrahedral and octahedral crystal field symmetry. These have been calculated using a localized description for the 3dⁿ to 2p⁵3dⁿ⁺¹ excitation including electrostatic and spin-orbit interactions. The spectra are significantly different from those already presented where the 3d spin-orbit interaction was neglected. The spectral shape provides a valence- and symmetry-selective probe. Whereas it changes gradually with the crystal field, abrupt changes in the spectra are indicative of high-spin to low-spin transitions. These spin transitions are accompanied by a strong decrease in the 2p branching ratio. The calculated spectra provide a basis for the use of L_2,3 absorption spectroscopy in materials science and biological science. The limitations of these calculations and the use of configuration interaction are discussed.