High energy resolution core-level X-ray spectroscopy for electronic and structural characterization of osmium compounds

Abstract

A comprehensive study of the bulk solid OsCl3 and the molecular ion [Os(bpy)2(CO)Cl](+) is presented illustrating the application of RIXS and HERFD XANES spectroscopies to the investigation of both bulk materials and molecular complexes. In order to analyze the experimental results, DFT simulations were performed taking into account spin-orbit interaction. Calculations for both compounds resulted in good agreement with the experimental RIXS and HERFD XANES data, shedding light on the details of their local atomic and electronic structure. In particular, the spatial distribution of molecular orbitals was obtained, which allowed the determination of the origin of the absorption peaks. It was shown that for materials containing heavy atoms, only the application of advanced RIXS and HERFD XANES spectroscopies makes it possible to extract the information on local atomic and electronic structure details from XANES data.

Cerium(III) Nitrate Derived CeO2 Support Stabilising PtOx Active Species for Room Temperature CO Oxidation

“…It is well known that XANES is one of the best techniques for the determination of an oxidation state usually based on a linear dependence of an energy of absorption edge versus oxidation state of the studied element. However, in the case of 5d‐metals the shift of the absorption edge is less sensitive to the oxidation state than to the different ligands and symmetry of the metal site . The intensity of the first peak after absorption edge, so‐named as White Line (WL), represents the vacancy in the 5d orbitals of the 5d‐metal atoms and can be used for the estimation of its oxidation state.…”

“…However, in the case of 5d-metals the shift of the absorption edge is less sensitive to the oxidation state than to the different ligands and symmetry of the metal site. [59][60][61] The intensity of the first peak after absorption edge, so-named as White Line (WL), represents the vacancy in the 5d orbitals of the 5d-metal atoms and can be used for the estimation of its oxidation state. Using the XANES spectra of reference Pt 4 + compounds (individual nitrato complexes) and data from the literature for Pt(acac) 2 (Pt 2 + ), [9,62,63] it can be concluded that the oxidation state of Pt is close to Pt 2 + for the "PtO x /CeO 2 -220" catalyst after activation and at the different temperatures during the catalytic reaction.…”

Time-resolved X-ray absorption spectroscopy for the study of molecular systems relevant for artificial photosynthesis

“…The continuum spectrum is properly described using full multiple scattering [67,68] or the finite difference method [69]. The alternative approach is based on the calculation of electronic transitions between discrete molecular orbitals [70,71]. Virtual states approximate the unoccupied continuum in this case.…”

High‐Energy‐Resolution X‐ray Absorption Spectroscopy for Identification of Reactive Surface Species on Supported Single‐Site Iridium Catalysts

“…The direct observation of features by use of HERFD is superior to the so-called delta-mu technique that relies on enhancing spectrals ignatures by use of spectral difference techniques. [22] The few examples of the use of HERFD to investigate surfaces peciesi nclude investigationso ft he interactions of CO with small supported noble metal clusters [23,24] and with organoiron complexes. [20] Modernsynchrotron end-stations with multicrystal spectrometers allow efficient datac ollection that makes the technique comparable in accessibility to that of conventional static or dynamic fluorescence XAS.…”