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 °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.

中文翻译：

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来自 Fe K 边缘的 XAS 光谱的准确 Fe3+/Fe 比

摘要 在 194–520 °C 下退火的三种不同的富铁角闪石上测试了一种提取铁氧化态准确信息的新方法。该方法基于对 Fe-K 边缘 X 射线吸收光谱的前边缘结构的分析。前边缘带被解卷积为四个高斯分量，其中低能带和高能带对的积分强度与亚铁与铁离子的比率有关。这些 Fe3+/Fetot 比率已与使用独立技术（X 射线衍射和穆斯堡尔光谱）在相同样品上获得的比率进行了比较。实验数据允许建立校准曲线，该曲线与最近基于相同类型矿物的光谱数据的统计分析非常一致。