Differences between L₃ and L₂ X-ray absorption spectra

The L₃ and L₂ edges of transition metals show differences in their spectral shape. Also the ratio between the L₃ and L₂ edges is found to deviate from 2:1. The interactions responsible for these effects are: the multiplet effects and the 3d (4d) spin-orbit coupling. The electronic interactions and spin- and orbital polarizations of the valence electrons determine the ground state (symmetry) and determine the shape itself. For 4d systems the L₃ and L₂ are separated by a large core spin-orbit splitting of about 100 eV. Differences between their L₃ and L₂ edge originate from the weight transfer between the t_2g and e_g peaks due to the multiplet effects. Because this weight transfer is larger for L₃ edge, it is better to use the L₂ edge for a comparison to single particle calculations. The only interaction which can affect their branching ratio is the 4d spin-orbit coupling. For 3d systems the multiplet effects dominate all other interactions and the L₃ and L₂ are completely different and show their characteristic multiplet structure. The multiplet effects are large enough to affect also the branching ratio.