L2,3-edges X-ray absorption near edge structure (XANES) spectra – transitions from 2p to εs and εd levels – contain important information about the electronic structure of transition metals in materials and molecules.
To correctly interpret the XANES spectra, sophisticated modeling is required. While multiplet effects strongly affect X-ray spectra of 3d ions, 4d and 5d elements are much less affected. However, inclusion of spin-orbit coupling effects is critical, as some of the transitions from the 2p1/2 and 2p3/2 manifolds to εd levels are symmetrically forbidden. Analytical analysis is only possible for symmetrically coordinated ions, reducing computation time. To overcome this limitation a collaboration of Purdue University (USA) and Southern Federal University (Russia) developed an approach to simulate L2,3-edges spectra on the basis of relativistic DFT as implemented within ZORA approximation in the ADF suite. The spatial distribution of spin-dependent molecular orbitals was obtained with the ADF2010 package, and XANES spectra were calculated as excitations from the Ru 2p level to unoccupied molecular orbitals.
X-ray Absorption Near-Edge Spectroscopy, core excitations, spin-orbit coupling, TDDFT
I. Alperovich, G. Smolentsev, D. Moonshiram, J.W. Jurss, J.J. Concepcion, T.J. Meyer, A. Soldatov, Y. Pushkar Understanding the Electronic Structure of 4d Metal Complexes: From Molecular Spinors to L-Edge Spectra of a di-Ru Catalyst J. Am. Chem. Soc., 133 15786-15794 (2011).Key conceptsADF catalysis SOC-TDDFT spectroscopy XAS