Characterization of EXAFS for quantitative analysis of mixed species

Extended x-ray absorption fine structure (EXAFS) spectroscopy is an established technique for determining the nature of the coordination sphere about a given atom in relatively pure materials. Hence, EXAFS shows great potential for providing chemical speciation of environmental samples. However, it is not clear whether EXAFS can be used to quantify more than one species of the same analyte atom in a sample. The authors have characterized the silicon EXAFS data for various mixtures of Ca-Mg and Li-Al pyroxenes (two very similar silicate structures) as well as the Cr EXAFS of various mixtures of oxides and nitrates. This investigation has revealed some of the limitations and potential applications of quantitative EXAFS.