Influence of Local Atomic and Electronic Structures of Magnetite on Subtle Effects in HERFD-XANES Spectra

Resumo

Large iron oxide nanoparticles are studied by high-energy resolution fluorescence-detected X-ray absorption spectroscopy (HERFD XANES). A theoretical procedure within the finite-difference method framework is tested to calculate Fe K-edge X-ray absorption spectra for the magnetite structure. The influence of structural and non-structural calculation parameters on the subtle effects in the X-ray absorption spectra are considered. Tetrahedral positions of Fe³⁺ ions are shown to provide the main contribution to the spectral feature at 20–21 eV whose intensity grows together with the content of these ions.