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Accurate Fe3+/Fe ratio from XAS spectra at the Fe K-edge

DOI: 10.1016/j.radphyschem.2018.12.008 DOI Help

Authors: Federico Galdenzi (University of Roma Tre; INFN-LNF) , Giancarlo Della Ventura (University of Roma Tre; INFN-LNF) , Giannantonio Cibin (Diamond Light Source) , Salvatore Macis (Università di Tor Vergata; RICMASS, Rome International Center for Materials Science Superstripes) , Augusto Marcelli (INFN-LNF; RICMASS, Rome International Center for Materials Science Superstripes)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Radiation Physics And Chemistry

State: Published (Approved)
Published: December 2018

Abstract: A new approach to extract accurate information on the Fe oxidation state has been tested on three different Fe-rich amphiboles annealed at 194 °C and 520 °C. The method is based on the analysis of the pre-edge structure of the X-ray absorption spectra at the Fe-K edge. The pre-edge band is deconvolved into four Gaussian components where the integrated intensities of the pairs of lower- and higher-energy bands are related to the ferrous to ferric ion ratio. These Fe3+/Fetot ratios have been compared with those obtained with independent techniques (X-ray diffraction and Mossbauer spectroscopy) on the same samples. The experimental data allowed establishing a calibration curve that is in good agreement with a recent statistical analysis based on spectroscopic data for the same type of minerals. The method could be extended to the analysis of other complex systems containing both Fe3+ and Fe2+ in octahedral coordination or to study the dynamics of iron under non-ambient conditions.

Subject Areas: Chemistry

Instruments: B18-Core EXAFS