First-principles calculations of X-ray absorption spectra at the K-edge of 3d transition metals: an electronic structure analysis of the pre-edge

Abstract

. First-principles calculations of X-ray absorption spectra at the K-edge of 3d transition metals: an electronic structure analysis of the pre-edge. Physical Chemistry Chemical Physics, Royal Society of Chemistry, 2010Chemistry, , 12, pp.5619-5633. 10.1039 This paper is published as part of a PCCP themed issue on recent developments in X-ray absorption spectroscopy Complementarity between high-energy photoelectron and L-edge spectroscopy for probing the electronic structure of 5d transition metal catalysts Toyli Anniyev, Hirohito Ogasawara, Mathias P. First-principles calculations of X-ray absorption spectra at the K-edge of 3d transition metals: an electronic structure analysis of the pre-edge We first present an extended introduction of the various methods used to extract electronic and structural information from the K pre-edge X-ray absorption spectra of 3d transition metal ions. The K pre-edge structure is then modelled for a selection of 3d transition metal compounds and analyzed using first-principles calculations based on the density functional theory (DFT) in the local density approximation (LDA). The selected compounds under study are presented in an ascending order of electronic structure complexity, starting with the Ti K-edge of rutile and anatase, and finishing with the Fe K-edge of the cyanomet-myoglobin. In most cases, the calculations are compared to polarized experimental spectra. It is shown that DFT-LDA methods enable us to reproduce satisfactorily the experimental features and to understand the nature of the electronic transitions involved in the pre-edge region. The limiting aspects of such methods in modelling the core-hole electron interaction and the 3d electron-electron repulsion are also pointed out.

Spin-state studies with XES and RIXS: From static to ultrafast

“…These techniques probe the bulk properties of the sample, and are even compatible with extreme conditions due to the large penetration depths [12]. X-ray Absorption Spectroscopy (XAS) with its variants X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) have proven their utility in determining the unoccupied electron states and the local structure, respectively [13,14,15,16]. X-ray Emission Spectroscopy (XES) and Resonant Inelastic X-ray Scattering (RIXS) are very powerful in elucidating the electronic structure, providing information on the electron energies, local geometry, spin and valence state, etc.…”

1s2p RIXS Calculations for 3d Transition Metal Ions in Octahedral Symmetry

“…The ground state 4 T 1g splits due to 3d SOC into the three odd symmetries E 1/2g , E 5/2g , and F 3/2g from which the term E 1/2g is lowest in energy; hence, the combined ground state is 4 T 1g E 1/2g (O h ). Figure 53 confirm these findings.…”

“…Hence, we give the splitting of the two reachable intermediate state terms 4 T 1g and 4 E g due to SOC (S = 3/2 → ⊗ F 3/2 ):…”

“…Consequently, it appears that in the case of low spin Mn 3+ , depending on the RIXS intermediate states that are probed, one can enhance either the transitions into the t 2g orbitals of the final states or the transitions into the e g orbitals. 4 Systems. Experimental 1s2p RIXS spectra of a number of Mn 3+ 3d 4 systems have been published by Glatzel et al [43] for Mn 2 O 3 and also for a series of molecular complexes that serve as reference systems for photosystem II.…”

“…In the case of inversion symmetry, local 4p3d mixing is forbidden by symmetry, but a nonlocal mixing of the local 4p orbitals with the 3d orbitals of the neighbouring ligands (→nonlocal) can alter the pre-edge structure and produce additionally the so-called nonlocal peaks [3][4][5][6][7][8] (e.g., TiO 2 [3] and CrO 2 [9]). …”