A new approach to extract accurate information on the Fe oxidation state has been tested on three different Fe-rich amphiboles annealed at 194-520 degrees 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+/Fe-tot 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.

Accurate Fe3+/Fe-tot ratio from XAS spectra at the Fe K-edge / Galdenzi, F; Della Ventura, G; Cibin, G; Macis, S; Marcelli, A. - In: RADIATION PHYSICS AND CHEMISTRY. - ISSN 0969-806X. - 175:(2020), p. 108088. [10.1016/j.radphyschem.2018.12.008]

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

Macis, S;
2020

Abstract

A new approach to extract accurate information on the Fe oxidation state has been tested on three different Fe-rich amphiboles annealed at 194-520 degrees 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+/Fe-tot 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.
2020
Iron; Mossbauer spectroscopy; Spectroscopic analysis; X ray absorption; amphiboles
01 Pubblicazione su rivista::01a Articolo in rivista
Accurate Fe3+/Fe-tot ratio from XAS spectra at the Fe K-edge / Galdenzi, F; Della Ventura, G; Cibin, G; Macis, S; Marcelli, A. - In: RADIATION PHYSICS AND CHEMISTRY. - ISSN 0969-806X. - 175:(2020), p. 108088. [10.1016/j.radphyschem.2018.12.008]
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11573/1681216
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