X-ray absorption spectroscopic study of Fe reference compounds for the analysis of natural sediments
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Peggy A. Oʼday
,
Nelson Rivera
Abstract
Synchrotron X-ray absorption spectroscopy (XAS) is becoming an increasingly popular tool for the analysis of element speciation in complex natural mixtures such as soils and sediments. Identification of a particular mineral or amorphous solid in a heterogeneous mixture by XAS depends on the spectral uniqueness of the element in the bonding environment associated with a component, and on absorption effects from the components and the matrix. A suite of 27 common, Fe-bearing reference compounds, including sulfides, carbonates, phosphates, oxides, oxyhydroxides, and phyllosilicates, was analyzed to empirically assess the utility of X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) for identifying a particular Fe mineral (or class of minerals) in a soil or sediment mixture. We show that XANES spectral features are useful for distinguishing qualitatively among major mineral classes, but not necessarily for identifying minerals within classes. A practical detection limit (based on empirical mixtures) for most mineral classes is on the order of 5% of the total atomic Fe absorption, but detection limits vary depending on the spectral uniqueness of the components, the number of components, and the matrix. Calibration curves for Fe sulfide and non-sulfide (phyllosilicate ± oxide) component mixtures were made independently from the analyses of XANES and EXAFS fluorescence spectra of binary and ternary mineral mixtures (at 5% total Fe) in a quartz matrix to mimic natural sediments. Because of differences in sample and matrix absorption and fluorescence among sulfide and phyllosilicate minerals, apparent component fractions of pyrite derived from fits deviated significantly from linear binary mixtures. We show that corrections for non-linear fluorescence (as much as 20%) are particularly important for binary mineral mixtures with different densities and absorption characteristics (such as sulfides and phyllosilicates), and for mixtures with similar component abundances (i.e., far from one end-member). An application of the fluorescence calibration for XANES and EXAFS is shown for natural samples. This study points out the importance of a high-quality, experimentally consistent reference compound library, and the need for calibration of fluorescence spectra, in order to quantify accurately the component fractions of complex mixtures using XAS.
© 2015 by Walter de Gruyter Berlin/Boston
Articles in the same Issue
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- Unoccupied states of pyrite probed by electron energy-loss spectroscopy (EELS)
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- SIMS microanalyses for Au in silicates
- Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the Varuträsk granitic pegmatite, Sweden: The case of an “anomalous” columbite-tantalite trend
- An X-ray and electron microprobe study of Fe, Ni, Ga, and Ge distribution and local structure in a section of the Canyon Diablo iron meteorite
- Mineralogical approaches to fundamental crystal dissolution kinetics
- Cu L3X-ray absorption spectroscopy and the electronic structure of minerals: Spectral variations in non-stoichiometric bornites, Cu5FeS4
- A new nondestructive X-ray method for the determination of the 3D mineralogy at the micrometer scale
- Dissolution rates and pit morphologies of rhombohedral carbonate minerals
- The effect of TiO2on Pd, Ni, and Fe solubilities in silicate melts
- X-ray absorption spectroscopic study of Fe reference compounds for the analysis of natural sediments
- A survey of hydrous species and concentrations in igneous feldspars
- Structure and crystallization behavior of the (Ba,Sr)HAsO4·H2O solid-solution in aqueous environments
- The crystal structure of painite CaZrB[Al9O18] revisited
- Model pyroxenes II: Structural variation as a function of tetrahedral rotation
- Mn-rich fluorapatite from Austria: Crystal structure, chemical analysis, and spectroscopic investigations
- Isothermal equation of state and compressional behavior of tetragonal edingtonite
- Synthesis and crystal-chemistry of Na(NaMg)Mg5Si8O22(OH)2, a P21/m amphibole
- A single-crystal study on the pressure behavior of phlogopite and petrological implications
- Quantitative electron microprobe analysis of Fe3+/ΣFe: Basic concepts and experimental protocol for glasses
Articles in the same Issue
- A zero-damage model for fission-track annealing in zircon
- Unoccupied states of pyrite probed by electron energy-loss spectroscopy (EELS)
- Tugtupite: High-temperature structures obtained from in situ synchrotron diffraction and Rietveld refinements
- SIMS microanalyses for Au in silicates
- Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the Varuträsk granitic pegmatite, Sweden: The case of an “anomalous” columbite-tantalite trend
- An X-ray and electron microprobe study of Fe, Ni, Ga, and Ge distribution and local structure in a section of the Canyon Diablo iron meteorite
- Mineralogical approaches to fundamental crystal dissolution kinetics
- Cu L3X-ray absorption spectroscopy and the electronic structure of minerals: Spectral variations in non-stoichiometric bornites, Cu5FeS4
- A new nondestructive X-ray method for the determination of the 3D mineralogy at the micrometer scale
- Dissolution rates and pit morphologies of rhombohedral carbonate minerals
- The effect of TiO2on Pd, Ni, and Fe solubilities in silicate melts
- X-ray absorption spectroscopic study of Fe reference compounds for the analysis of natural sediments
- A survey of hydrous species and concentrations in igneous feldspars
- Structure and crystallization behavior of the (Ba,Sr)HAsO4·H2O solid-solution in aqueous environments
- The crystal structure of painite CaZrB[Al9O18] revisited
- Model pyroxenes II: Structural variation as a function of tetrahedral rotation
- Mn-rich fluorapatite from Austria: Crystal structure, chemical analysis, and spectroscopic investigations
- Isothermal equation of state and compressional behavior of tetragonal edingtonite
- Synthesis and crystal-chemistry of Na(NaMg)Mg5Si8O22(OH)2, a P21/m amphibole
- A single-crystal study on the pressure behavior of phlogopite and petrological implications
- Quantitative electron microprobe analysis of Fe3+/ΣFe: Basic concepts and experimental protocol for glasses
