Ru L2,3-edges XANES specta of a di-Ruthenium catalyst
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.
An excellent agreement between experiment and theory was demonstrated for the complex di-Ru catalyst cis,cis-[(bpy)2(H2O)RuIIIORuIII(OH2)(bpy)2]4+ (bpy = 2,2-bipyridine).
