Artykuły w czasopismach: „XANES”

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Natori, Sachika, Minako Kurisu, Naomi Kawamura i Yoshio Takahashi. "High-Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy for the Speciation of Fe in Aerosol Samples". Minerals 12, nr 5 (26.04.2022): 536. http://dx.doi.org/10.3390/min12050536.

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In this study, we compared the high-energy resolution X-ray fluorescence X-ray absorption near-edge structure (HERFD-XANES) and normal XANES spectra of various iron (Fe) species and Fe in atmospheric aerosol samples to explore the advantages of Fe K-edge HERFD-XANES for Fe speciation in aerosols using the linear combination fitting (LCF) of XANES spectra. We also conducted Fe extraction experiments to validate the LCF-XANES. In the HERFD-XANES spectra, the pre-edge region showed specific structures absent in normal XANES. HERFD-XANES also produced more distinctive shoulders within each spectrum than normal XANES. HERFD-XANES was applied to an aerosol sample (MT21-S2) collected in Tokyo, Japan. Normal XANES identified ferrihydrite, biotite, and montmorillonite, whereas HERFD-XANES clearly detected goethite as a fourth component. Normal XANES did not distinguish between ferrihydrite and goethite in LCF because of their similar structures. A similar trend was observed in the pre-edge region, and the Fe extraction experiment result was consistent with the LCF result in the pre-edge region. Thus, LCF of HERFD-XANES, in particular for the pre-edge region, can be a powerful tool for Fe speciation in aerosols.

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Natori, Sachika, Minako Kurisu, Naomi Kawamura i Yoshio Takahashi. "High-Energy Resolution Fluorescence Detected X-ray Absorption Spectroscopy for the Speciation of Fe in Aerosol Samples". Minerals 12, nr 5 (26.04.2022): 536. http://dx.doi.org/10.3390/min12050536.

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In this study, we compared the high-energy resolution X-ray fluorescence X-ray absorption near-edge structure (HERFD-XANES) and normal XANES spectra of various iron (Fe) species and Fe in atmospheric aerosol samples to explore the advantages of Fe K-edge HERFD-XANES for Fe speciation in aerosols using the linear combination fitting (LCF) of XANES spectra. We also conducted Fe extraction experiments to validate the LCF-XANES. In the HERFD-XANES spectra, the pre-edge region showed specific structures absent in normal XANES. HERFD-XANES also produced more distinctive shoulders within each spectrum than normal XANES. HERFD-XANES was applied to an aerosol sample (MT21-S2) collected in Tokyo, Japan. Normal XANES identified ferrihydrite, biotite, and montmorillonite, whereas HERFD-XANES clearly detected goethite as a fourth component. Normal XANES did not distinguish between ferrihydrite and goethite in LCF because of their similar structures. A similar trend was observed in the pre-edge region, and the Fe extraction experiment result was consistent with the LCF result in the pre-edge region. Thus, LCF of HERFD-XANES, in particular for the pre-edge region, can be a powerful tool for Fe speciation in aerosols.

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Nicholls, M., M. N. Najman, Z. Zhang, M. Kasrai, P. R. Norton i P. U. P. A. Gilbert. "The contribution of XANES spectroscopy to tribology". Canadian Journal of Chemistry 85, nr 10 (1.10.2007): 816–30. http://dx.doi.org/10.1139/v07-093.

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X-ray absorption near edge structure spectroscopy (XANES) analysis has been routinely used to study the complex chemical interactions between additives in engine oil and metallic surfaces during high-temperature and pressure reciprocating wear conditions. XANES analysis provides detailed chemical and structural information on the resultant antiwear and tribo films formed on metallic surfaces. The following review will illustrate how XANES analysis on the macro scale can provide the information required to elucidate complex film formation mechanisms, then describes the use of emerging XANES spectromicroscopy to such systems, and concludes by showing the complementary nature of the macro and micro scale spatially resolved XANES analysis; Professor Bancroft has utilized the combination of these to stay at the forefront of XANES research in the field of tribology and in spectroscopy science in general.Key words: tribology, XANES, X-ray absorption near edge structure spectroscopy, metals, thiophosphates, spectromicroscopy, tribochemistry.

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Ge, Mingyuan, i Wah-Keat Lee. "PyXAS – an open-source package for 2D X-ray near-edge spectroscopy analysis". Journal of Synchrotron Radiation 27, nr 2 (20.02.2020): 567–75. http://dx.doi.org/10.1107/s1600577520001071.

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In the synchrotron X-ray community, X-ray absorption near-edge spectroscopy (XANES) is a widely used technique to probe the local coordination environment and the oxidation states of specific elements within a sample. Although this technique is usually applied to bulk samples, the advent of new synchrotron sources has enabled spatially resolved versions of this technique (2D XANES). This development has been extremely powerful for the study of heterogeneous systems, which is the case for nearly all real applications. However, associated with the development of 2D XANES comes the challenge of analyzing very large volumes of data. As an example, a single 2D XANES measurement at a synchrotron can easily produce ∼106 spatially resolved XANES spectra. Conventional manual analysis of an individual XANES spectrum is no longer feasible. Here, a software package is described that has been developed for high-throughput 2D XANES analysis. A detailed description of the software as well as example applications are provided.

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Kizler, P., P. Lamparter i S. Steeb. "X -Ray Absorption Near Edge Structure (XANES) Calculations for the Amorphous Fe80B20- and Ni80B20-Alloys". Zeitschrift für Naturforschung A 44, nr 3 (1.03.1989): 189–94. http://dx.doi.org/10.1515/zna-1989-0304.

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Xanes spectra of the amorphous Fe80B20- and Ni80B20-alloys have been investigated using the electron multiple scattering theory of Durham et al. The calculations were based on several models for the structure of amorphous Fe80B20 and Ni80B20. Very good agreement between theoretical and experimental XANES curves was met. Opposite to former expectations for obtaining information on bond angles by XANES, this study shows that XANES points to more complex features of the structure than can be expressed in terms of bond angles.

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Park, Jae Yeon, Jitendra Pal Singh, Jun Lim i Sangsul Lee. "Development of XANES nanoscopy on BL7C at PLS-II". Journal of Synchrotron Radiation 27, nr 2 (20.02.2020): 545–50. http://dx.doi.org/10.1107/s160057752000082x.

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X-ray absorption near-edge structure (XANES) imaging is a powerful tool to visualize the chemical state distribution of transition-metal-based materials at synchrotron radiation facilities. In recent years, the electrochemical working rechargeable battery has been the most studied material in XANES imaging owing to the large increase of portable electronics and electric vehicles. This work acknowledges the importance of battery analysis and has developed the XANES imaging system on BL7C at Pohang Light Source-II (PLS-II). BL7C employs an undulator taper configuration to obtain an energy band >130 eV near the K-absorption edge of the target element with a minimum energy interval >0.2 eV. While measuring energy-dependent images, the zone plate translation maintains the best focus, and then various data processes such as background correction, image registration and clustering allow single XANES spectrum extraction and chemical distribution mapping. Here, the XANES imaging process is described, the XANES spectrum quality is identified and the chemical states of the partially charged cathode material used in lithium-ion batteries as an application example are examined.

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Pongpiachan, Siwatt, Kanjana Thumanu, Charnwit Kositanont, Klaus Schwarzer, Jörg Prietzel, Phoosak Hirunyatrakul i Itthipon Kittikoon. "Parameters Influencing Sulfur Speciation in Environmental Samples Using Sulfur K-Edge X-Ray Absorption Near-Edge Structure". Journal of Analytical Methods in Chemistry 2012 (2012): 1–12. http://dx.doi.org/10.1155/2012/659858.

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This paper aims to enhance the credibility of applying the sulfur K-edge XANES spectroscopy as an innovative “fingerprint” for characterizing environmental samples. The sensitivities of sulfur K-edge XANES spectra of ten sulfur compound standards detected by two different detectors, namely, Lytle detector (LyD) and Germanium detector (GeD), were studied and compared. Further investigation on “self-absorption” effect revealed that the maximum sensitivities of sulfur K-edge XANES spectra were achieved when diluting sulfur compound standards with boron nitride (BN) at the mixing ratio of 0.1%. The “particle-size” effect on sulfur K-edge XANES spectrum sensitivities was examined by comparing signal-to-noise ratios of total suspended particles (TSP) and particulate matter of less than 10 millionths of a meter(PM10)collected at three major cities of Thailand. The analytical results have demonstrated that the signal-to-noise ratios of sulfur K-edge XANES spectra were positively correlated with sulfate content in aerosols and negatively connected with particle sizes. The combination of hierarchical cluster analysis (HCA) and principal component analysis (PCA) has proved that sulfur K-edge XANES spectrum can be used to characterize German terrestrial soils and Andaman coastal sediments. In addition, this study highlighted the capability of sulfur K-edge XANES spectra as an innovative “fingerprint” to distinguish tsunami backwash deposits (TBD) from typical marine sediments (TMS).

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Price, S. W. T., K. Ignatyev, K. Geraki, M. Basham, J. Filik, N. T. Vo, P. T. Witte, A. M. Beale i J. F. W. Mosselmans. "Chemical imaging of single catalyst particles with scanning μ-XANES-CT and μ-XRF-CT". Physical Chemistry Chemical Physics 17, nr 1 (2015): 521–29. http://dx.doi.org/10.1039/c4cp04488f.

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Leri, Alessandra C., i Bruce Ravel. "Sample thickness and quantitative concentration measurements in BrK-edge XANES spectroscopy of organic materials". Journal of Synchrotron Radiation 21, nr 3 (12.03.2014): 623–26. http://dx.doi.org/10.1107/s1600577514001283.

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While XANES spectroscopy is an established tool for quantitative information on chemical structure and speciation, elemental concentrations are generally quantified by other methods. The edge step in XANES spectra represents the absolute amount of the measured element in the sample, but matrix effects and sample thickness complicate the extraction of accurate concentrations from XANES measurements, particularly at hard X-ray energies where the X-ray beam penetrates deeply into the sample. The present study demonstrates a method of quantifying concentration with a detection limit approaching 1 mg kg−1using information routinely collected in the course of a hard X-ray XANES experiment. The XANES normalization procedure unambiguously separates the signal of the absorber from any source of background. The effects of sample thickness on edge steps at the bromineK-edge were assessed and an empirical correction factor for use with samples of variable mass developed.

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RANJAN, RAKESH KUMAR. "Derivation of Relation between a parameter of Inverse correlation and effective Charge of X-ray absorbing K-Edge of Copper atom in it’s different Compounds". Journal of Ultra Scientist of Physical Sciences Section B 32, nr 5 (31.10.2020): 31–35. http://dx.doi.org/10.22147/jusps-b/320501.

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The article gives an overview of the XANES technique contribution to the analysis of multi-component catalysts. The theoretical basis of the technique, the interpretation of the energy position and intensity of XANES features, and the numerical methods developed to interpret XANES data on catalytic systems are described and discussed. XANES in the K-edge of copper in the systems. CuO, Cu(NO3)2, La2CuO4, CuCl2, and CuBr have been investigated and transitions have been assigned to the observed structures. The measurements have been used for calculating the first coordination bond distance in the above systems. It is observed that the values so determined agree fairly well with crystallographic values

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Wakita, Hisanobu, Toshio Yamaguchi, Hirohiko Adachi, Manabu Fujiwara i Seiichi Yamashita. "A Xanes Study of Square Copper(II) Complexes". Advances in X-ray Analysis 35, B (1991): 1115–20. http://dx.doi.org/10.1154/s0376030800013380.

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AbstractThe XANES (X-ray absorption near edge structure) spectra of copper(II) ions in solid state and in solution of the square-planar copper(II) complexes with tetraaza macrocycles were measured. The peaks in the measured XANES spectra shifted to lower energy side with increasing the electron density of central copper(II) ions. The molecular orbital calculations for the complexes were carried out by the DV-Xα method, and the theoretical XANES spectra were estimated. The clear chemical shift obtained by this XANES study is evaluated and leads to a new concept of π-back donation between the copper(II) complexes and counter anion in aqueous solution.

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Zhang, Linjuan, Jing Zhou, Jianyong Zhang, Jing Su, Shuo Zhang, Ning Chen, Yunpeng Jia, Jiong Li, Yu Wang i Jian-Qiang Wang. "Extraction of local coordination structure in a low-concentration uranyl system by XANES". Journal of Synchrotron Radiation 23, nr 3 (24.03.2016): 758–68. http://dx.doi.org/10.1107/s1600577516001910.

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Obtaining structural information of uranyl species at an atomic/molecular scale is a critical step to control and predict their physical and chemical properties. To obtain such information, experimental and theoreticalL3-edge X-ray absorption near-edge structure (XANES) spectra of uranium were studied systematically for uranyl complexes. It was demonstrated that the bond lengths (R) in the uranyl species and relative energy positions (ΔE) of the XANES were determined as follows: ΔE1= 168.3/R(U—Oax)2− 38.5 (for the axial plane) and ΔE2= 428.4/R(U—Oeq)2− 37.1 (for the equatorial plane). These formulae could be used to directly extract the distances between the uranium absorber and oxygen ligand atoms in the axial and equatorial planes of uranyl ions based on the UL3-edge XANES experimental data. In addition, the relative weights were estimated for each configuration derived from the water molecule and nitrate ligand based on the obtained average equatorial coordination bond lengths in a series of uranyl nitrate complexes with progressively varied nitrate concentrations. Results obtained from XANES analysis were identical to that from extended X-ray absorption fine-structure (EXAFS) analysis. XANES analysis is applicable to ubiquitous uranyl–ligand complexes, such as the uranyl–carbonate complex. Most importantly, the XANES research method could be extended to low-concentration uranyl systems, as indicated by the results of the uranyl–amidoximate complex (∼40 p.p.m. uranium). Quantitative XANES analysis, a reliable and straightforward method, provides a simplified approach applied to the structural chemistry of actinides.

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Blake, Anastasia V., Haochuan Wei, Courtney M. Donahue, Kyounghoon Lee, Jason M. Keith i Scott R. Daly. "Solid energy calibration standards for PK-edge XANES: electronic structure analysis of PPh4Br". Journal of Synchrotron Radiation 25, nr 2 (20.02.2018): 529–36. http://dx.doi.org/10.1107/s1600577518000528.

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PK-edge X-ray absorption near-edge structure (XANES) spectroscopy is a powerful method for analyzing the electronic structure of organic and inorganic phosphorus compounds. Like all XANES experiments, PK-edge XANES requires well defined and readily accessible calibration standards for energy referencing so that spectra collected at different beamlines or under different conditions can be compared. This is especially true for ligandK-edge X-ray absorption spectroscopy, which has well established energy calibration standards for Cl (Cs2CuCl4) and S (Na2S2O3·5H2O), but not neighboring P. This paper presents a review of common PK-edge XANES energy calibration standards and analysis of PPh4Br as a potential alternative. The PK-edge XANES region of commercially available PPh4Br revealed a single, highly resolved pre-edge feature with a maximum at 2146.96 eV. PPh4Br also showed no evidence of photodecomposition when repeatedly scanned over the course of several days. In contrast, we found that PPh3rapidly decomposes under identical conditions. Density functional theory calculations performed on PPh3and PPh4+revealed large differences in the molecular orbital energies that were ascribed to differences in the phosphorus oxidation state (IIIversusV) and molecular charge (neutralversus+1). Time-dependent density functional theory calculations corroborated the experimental data and allowed the spectral features to be assigned. The first pre-edge feature in the PK-edge XANES spectrum of PPh4Br was assigned to P 1s → P-C π* transitions, whereas those at higher energy were P 1s → P-C σ*. Overall, the analysis suggests that PPh4Br is an excellent alternative to other solid energy calibration standards commonly used in PK-edge XANES experiments.

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Nakada, Ryoichi, Tomohiro Usui, Masashi Ushioda i Yoshio Takahashi. "Vanadium micro-XANES determination of oxygen fugacity in olivine-hosted glass inclusion and groundmass glasses of martian primitive shergottite Yamato 980459". American Mineralogist 105, nr 11 (1.11.2020): 1695–703. http://dx.doi.org/10.2138/am-2020-7321.

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Abstract The redox condition of magma determines the stability and composition of crystallizing and volatile phases in martian meteorites, reflecting the evolution of the martian interior. In the current study, direct analyses on the oxidation states of V, Cr, and Fe were performed based on the X-ray absorption near-edge structure (XANES) measurements equipped with a micro-sized X-ray beam. We first applied the micro-XANES (μ-XANES) technique to the olivine-hosted glass inclusion and groundmass glass of martian meteorite Yamato 980459 (Y98), which is interpreted as representing a primary melt composition. Mass-balance calculations and XANES spectra comparisons indicated that, while chromite and pyroxene affected Cr and Fe K-edge XANES spectra, the contribution of these minerals was minimal for V. The pre-edge peak intensity of V K-edge XANES enabled the estimation of the oxygen fugacity for inclusion and groundmass glasses. The calculated oxygen fugacity (fO2) of the glass inclusions was near the Iron-Wüstite (IW) buffer (IW-0.07 ± 0.32) for the glass inclusion, whereas it was 0.9 log units more oxidized (IW+0.93 ± 0.56) for the groundmass glasses. This result suggests that the redox condition of the parent magma of Y98 evolved during magma ascent and emplacement. Since Y98 is interpreted to have evolved in a closed system, our finding suggests that fractional crystallization and/or ascent of magma potentially induces the fO2 increase. This study shows that the μ-XANES technique enables us to determine the fO2 by only measuring a single phase of glassy compounds, and thus, it is useful to discuss the redox condition of volcanic rocks even if they do not crystallize out several equilibrium phases of minerals.

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Nelson, Joey. "XANES reflects coordination change and underlying surface disorder of zinc adsorbed to silica". Journal of Synchrotron Radiation 28, nr 4 (28.05.2021): 1119–26. http://dx.doi.org/10.1107/s1600577521004033.

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Zinc K-edge X-ray absorption near-edge structure (XANES) spectroscopy of Zn adsorbed to silica and Zn-bearing minerals, salts and solutions was conducted to explore how XANES spectra reflect coordination environment and disorder in the surface to which a metal ion is sorbed. Specifically, XANES spectra for five distinct Zn adsorption complexes (Znads) on quartz and amorphous silica [SiO2(am)] are presented from the Zn–water–silica surface system: outer-sphere octahedral Znads on quartz, inner-sphere octahedral Znads on quartz, inner-sphere tetrahedral Znads on quartz, inner-sphere octahedral Znads on SiO2(am) and inner-sphere tetrahedral Znads on SiO2(am). XANES spectral analysis of these complexes on quartz versus SiO2(am) reveals that normalized peak absorbance and K-edge energy position generally decrease with increasing surface disorder and decreasing Zn–O coordination. On quartz, the absorption-edge energy of Znads ranges from 9663.0 to 9664.1 eV for samples dominated by tetrahedrally versus octahedrally coordinated species, respectively. On SiO2(am), the absorption-edge energy of Znads ranges from 9662.3 to 9663.4 eV for samples dominated by tetrahedrally versus octahedrally coordinated species, respectively. On both silica substrates, octahedral Znads presents a single K-edge peak feature, whereas tetrahedral Znads presents two absorbance features. The energy space between the two absorbance peak features of the XANES K-edge of tetrahedral Znads is 2.4 eV for Zn on quartz and 3.2 eV for Zn on SiO2(am). Linear combination fitting of samples with a mixture of Znads complex types demonstrates that the XANES spectra of octahedral and tetrahedral Znads on silica are distinct enough for quantitative identification. These results suggest caution when deciphering Zn speciation in natural samples via linear combination approaches using a single Znads standard to represent sorption on a particular mineral surface. Correlation between XANES spectral features and prior extended X-ray absorption fine structure (EXAFS) derived coordination environments for these Znads on silica samples provides insight into Zn speciation in natural systems with XANES compatible Zn concentrations too low for EXAFS analysis.

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Yi, Jun, Naoki Nakatani i Kotohiro Nomura. "Solution XANES and EXAFS analysis of active species of titanium, vanadium complex catalysts in ethylene polymerisation/dimerisation and syndiospecific styrene polymerisation". Dalton Transactions 49, nr 24 (2020): 8008–28. http://dx.doi.org/10.1039/d0dt01139h.

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Mechanistic studies through the solution XANES and EXAFS analysis for V and Ti complex catalysed ethylene polymerisation/dimerization, and syndiospecific styrene polymerisation, including interpretation of the XANES spectra, have been introduced.

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Martini, A., A. A. Guda, S. A. Guda, A. L. Bugaev, O. V. Safonova i A. V. Soldatov. "Machine learning powered by principal component descriptors as the key for sorted structural fit of XANES". Physical Chemistry Chemical Physics 23, nr 33 (2021): 17873–87. http://dx.doi.org/10.1039/d1cp01794b.

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A novel PCA based XANES fit is introduced. This approach selects those combinations of structural parameters affecting more the variation of a XANES spectrum and determines the amount of accessible structural information.

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Boonkerd, Kanoktip, i Wanwisa Limphirat. "The Influence of Chemical Compounds on the Sulfur K-Edge X-Ray Absorption near Edge Spectrum of the Vulcanized Rubber". Advanced Materials Research 905 (kwiecień 2014): 128–31. http://dx.doi.org/10.4028/www.scientific.net/amr.905.128.

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The vulcanized styrene-butadiene rubber (SBR) was studied using X-ray absorption near edge spectroscopy (XANES). The effect of the sulfur containing molecules left over in the sample on the precision of the sulfur K-edge XANES spectrum was focused. The six rubber compounds used here were vulcanized with different curing systems including convention, semi-efficiency and efficiency. For each compound, the measurements were preformed on two different samples which were the untreated and treated chloroform samples. The results showed when compounds were cured with conventional or semi-efficient vulcanization system, the XANES spectra between the untreated and treated sample was changed with very high sulfur to accelerator ratio. On the other hand, the tremendous dissimilarity was observed when compounds were cured with the efficient vulcanization system. Thus the sample treatment was necessary when using XANES to identify sulfur crosslink.

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Anzures, Brendan A., Stephen W. Parman, Ralph E. Milliken, Antonio Lanzirotti i Matthew Newville. "XANES spectroscopy of sulfides stable under reducing conditions". American Mineralogist 105, nr 3 (1.03.2020): 375–81. http://dx.doi.org/10.2138/am-2020-7146.

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Abstract X-ray absorption near-edge structure (XANES) spectroscopy is a powerful technique to quantitatively investigate sulfur speciation in geologically complex materials such as minerals, glasses, soils, organic compounds, industrial slags, and extraterrestrial materials. This technique allows non-destructive investigation of the coordination chemistry and oxidation state of sulfur species ranging from sulfide (2–oxidation state) to sulfate (6+ oxidation state). Each sulfur species has a unique spectral shape with a characteristic K-edge representing the s → p and d hybridization photoelectron transitions. As such, sulfur speciation is used to measure the oxidation state of samples by comparing the overall XANES spectra to that of reference compounds. Although many S XANES spectral standards exist for terrestrial applications under oxidized conditions, new sulfide standards are needed to investigate reduced (oxygen fugacity, fO2, below IW) silicate systems relevant for studies of extraterrestrial materials and systems. Sulfides found in certain meteorites (e.g., enstatite chondrites and aubrites) and predicted to exist on Mercury, such as CaS (oldhamite), MgS (niningerite), and FeCr2S4 (daubréelite), are stable at fO2 below IW-3 but rapidly oxidize to sulfate and/or produce sulfurous gases under terrestrial surface conditions. XANES spectra of these compounds collected to date have been of variable quality, possibly due to the unstable nature of certain sulfides under typical (e.g., oxidizing) laboratory conditions. A new set of compounds was prepared for this study and their XANES spectra are analyzed for comparison with potential extraterrestrial analogs. S K-edge XANES spectra were collected at Argonne National Lab for FeS (troilite), MnS (alabandite), CaS (oldhamite), MgS (niningerite), Ni1–xS, NiS2, CaSO4 (anhydrite), MgSO4, FeSO4, Fe2(SO4)3, FeCr2S4 (daubréelite), Na2S, Al2S3, Ni7S6, and Ni3S2; the latter five were analyzed for the first time using XANES. These standards expand upon the existing S XANES end-member libraries at a higher spectral resolution (0.25 eV steps) near the S K-edge. Processed spectra, those that have been normalized and “flattened,” are compared to quantify uncertainties due to data processing methods. Future investigations that require well-characterized sulfide standards, such as the ones presented here, may have important implications for understanding sulfur speciation in reduced silicate glasses and minerals with applications for the early Earth, Moon, Mercury, and enstatite chondrites.

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Yadav, Ashok Kumar, Sk Maidul Haque, Shilpa Tripathi, Dinesh Shukla, Md A. Ahmed, D. M. Phase, S. Bandyopadhyay, S. N. Jha i D. Bhattacharyya. "Investigation of Fe doped ZnO thin films by X-ray absorption spectroscopy". RSC Advances 6, nr 78 (2016): 74982–90. http://dx.doi.org/10.1039/c6ra07195c.

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XANES and EXAFS studies have been carried out on Fe doped ZnO thin films having different Fe doping concentration ranging from 1% to 10% and the observed ferromagnetism in the samples is explained in the light of XANES and EXAFS observations.

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Vaithianathan, Veeramuthu, Jong Ha Moon, Chang-Hwan Chang, Kandasami Asokan i Sang Sub Kim. "Electronic Structure of P-Doped ZnO Films with p-Type Conductivity". Journal of Nanoscience and Nanotechnology 6, nr 11 (1.11.2006): 3422–25. http://dx.doi.org/10.1166/jnn.2006.17953.

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The electronic structure of laser-deposited P-doped ZnO films was investigated by X-ray absorption near-edge structure spectroscopy (XANES) at the O K-, Zn K-, and Zn L3-edges. While the O K-edge XANES spectrum of the n-type P-doped ZnO demonstrates that the density of unoccupied states, primarily O 2p–P 3sp hybridized states, is significantly high, the O K-edge XANES spectrum of the p-type P-doped ZnO shows a sharp decrease in intensity of the corresponding feature indicating that P replaces O sites in the ZnO lattice, and thereby generating PO. This produces holes to maintain charge neutrality that are responsible for the p-type behavior of P-doped ZnO. Both the Zn K-, and Zn L3-edge XANES spectra of the P-doped ZnO reveal that Zn plays no significant role in the p-type behavior of ZnO:P.

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Sham, T. K., i R. A. Gordon. "RIXS at the cerium L3-edge of Ce(III) and Ce(IV) systems: some observations". Canadian Journal of Chemistry 93, nr 2 (luty 2015): 218–26. http://dx.doi.org/10.1139/cjc-2014-0261.

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We report recent observations of resonant inelastic X-ray scattering (RIXS) at the cerium L3-edge of CePO4, CeO2, and Ce3+ ion in aqueous solution. The intensity of the emission spectrum, including the dispersive Raman below the edge and the emerging nondispersive fluorescence above the edge, was recorded with a solid-state detector with low-energy resolution and a WDX detector with modestly high-energy resolution. The yield of the emission was used to monitor the cerium L3-edge X-ray absorption near edge structures (XANES) in a constant initial state (CIS) mode as the photon energy sweeps across the cerium L3-edge. The CIS XANES is compared with the XANES recorded using the nondispersive fluorescence yield, Lα, in a constant final state (CFI) mode. It is found that the Raman yield dominates the total emission in the pre-edge region and diminishes rapidly at threshold. The RIXS of Ce3+ in aqueous solution exhibits similar behavior as CePO4. The post-whiteline RIXS intensity of CePO4 exhibits a correlation with excitation energy. CeO2 also exhibits a less intense whiteline in CIS XANES compared with the XANES detected with normal fluorescence. The implications of these observations with improved instrumental resolution are noted.

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Li, Zhigen, Peng Wang, Neal W. Menzies, Brigid A. McKenna, Chithra Karunakaran, James J. Dynes, Zachary Arthur i in. "Examining a synchrotron-based approach for in situ analyses of Al speciation in plant roots". Journal of Synchrotron Radiation 27, nr 1 (1.01.2020): 100–109. http://dx.doi.org/10.1107/s1600577519014395.

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Aluminium (Al) K- and L-edge X-ray absorption near-edge structure (XANES) has been used to examine Al speciation in minerals but it remains unclear whether it is suitable for in situ analyses of Al speciation within plants. The XANES analyses for nine standard compounds and root tissues from soybean (Glycine max), buckwheat (Fagopyrum tataricum), and Arabidopsis (Arabidopsis thaliana) were conducted in situ. It was found that K-edge XANES is suitable for differentiating between tetrahedral coordination (peak of 1566 eV) and octahedral coordination (peak of 1568 to 1571 eV) Al, but not suitable for separating Al binding to some of the common physiologically relevant compounds in plant tissues. The Al L-edge XANES, which is more sensitive to changes in the chemical environment, was then examined. However, the poorer detection limit for analyses prevented differentiation of the Al forms in the plant tissues because of their comparatively low Al concentration. Where forms of Al differ markedly, K-edge analyses are likely to be of value for the examination of Al speciation in plant tissues. However, the apparent inability of Al K-edge XANES to differentiate between some of the physiologically relevant forms of Al may potentially limit its application within plant tissues, as does the poorer sensitivity at the L-edge.

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Han, Kyoo-Seung, Masahiro Yoshimura, Joo-Byoung Yoon, Jin-Ho Choy i Kwang-Ja Park. "Pure tetravalent nickel in γ-type nickel oxyhydroxide as secondary battery electrode". Journal of Materials Research 13, nr 4 (kwiecień 1998): 880–82. http://dx.doi.org/10.1557/jmr.1998.0118.

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Pure tetravalent nickel in γ-type cobalt substituted nickel oxyhydroxide, Ni0.70Co0.30O2K0.30(H2O)0.42, could be obtained by the “chimie douce” reaction. The presence of tetravalent nickel is confirmed by comparing the Ni K-edge XANES spectrum of the sample with those of reference compounds having various nickel valency and similar layer structure. The Co K-edge XANES spectrum indicates that the trivalent cobalt remains unchanged regardless of the nickel valency. The structural modification during chimie douce reaction observed from XRD patterns and the result of iodometric titration are consistent with the Ni and Co K-edge XANES data.

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Kobayashi, Kenji, Hiroshi Kawata i Koichi Mori. "Site specification on normal and magnetic XANES of ferrimagnetic Fe3O4 by means of resonant magnetic Bragg scattering". Journal of Synchrotron Radiation 5, nr 3 (1.05.1998): 972–74. http://dx.doi.org/10.1107/s0909049597016646.

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Resonant magnetic Bragg scattering (RMBS) for several reflections has been measured at the Fe K-edge in Fe3O4. The normal and magnetic X-ray absorption near-edge structure (XANES) for two types of Fe ion site (tetrahedral and octahedral) were successfully determined from the analysis of DAFS and RMBS spectra on the assumption that there was an electric dipole transition. The obtained normal XANES for the octahedral site is well explained as a mixture of Fe2+ and Fe3+ ions, and the characteristic feature of the magnetic XANES at the pre-edge peak is mainly contributed from the Fe3+ ion at the tetrahedral site.

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Pattammattel, A., R. Tappero, M. Ge, Y. S. Chu, X. Huang, Y. Gao i H. Yan. "High-sensitivity nanoscale chemical imaging with hard x-ray nano-XANES". Science Advances 6, nr 37 (wrzesień 2020): eabb3615. http://dx.doi.org/10.1126/sciadv.abb3615.

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Resolving chemical species at the nanoscale is of paramount importance to many scientific and technological developments across a broad spectrum of disciplines. Hard x-rays with excellent penetration power and high chemical sensitivity are suitable for speciation of heterogeneous (thick) materials. Here, we report nanoscale chemical speciation by combining scanning nanoprobe and fluorescence-yield x-ray absorption near-edge structure (nano-XANES). First, the resolving power of nano-XANES was demonstrated by mapping Fe(0) and Fe(III) states of a reference sample composed of stainless steel and hematite nanoparticles with 50-nm scanning steps. Nano-XANES was then used to study the trace secondary phases in lithium iron phosphate (LFP) particles. We observed individual Fe-phosphide nanoparticles in pristine LFP, whereas partially (de)lithiated particles showed Fe-phosphide nanonetworks. These findings shed light on the contradictory reports on Fe-phosphide morphology in the literature. Nano-XANES bridges the capability gap of spectromicroscopy methods and provides exciting research opportunities across multiple disciplines.

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Pongpiachan, Siwatt, Kanjana Thumanu, Warangkana Na Pattalung, Phoosak Hirunyatrakul, Itthipon Kittikoon, Kin Fai Ho i Junji Cao. "Diurnal Variation and Spatial Distribution Effects on Sulfur Speciation in Aerosol Samples as Assessed by X-Ray Absorption Near-Edge Structure (XANES)". Journal of Analytical Methods in Chemistry 2012 (2012): 1–10. http://dx.doi.org/10.1155/2012/696080.

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This paper focuses on providing new results relating to the impacts ofDiurnal variation,Vertical distribution, andEmission sourceon sulfur K-edge XANES spectrum of aerosol samples. All aerosol samples used in the diurnal variation experiment were preserved using anoxic preservation stainless cylinders (APSCs) and pressure-controlled glove boxes (PCGBs), which were specially designed to prevent oxidation of the sulfur states in PM10. Further investigation of sulfur K-edge XANES spectra revealed that PM10samples were dominated by S(VI), even when preserved in anoxic conditions. The “Emission source effect” on the sulfur oxidation state of PM10was examined by comparing sulfur K-edge XANES spectra collected from various emission sources in southern Thailand, while “Vertical distribution effects” on the sulfur oxidation state of PM10were made with samples collected from three different altitudes from rooftops of the highest buildings in three major cities in Thailand. The analytical results have demonstrated that neither “Emission source” nor “Vertical distribution” appreciably contribute to the characteristic fingerprint of sulfur K-edge XANES spectrum in PM10.

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Pierre, Le Pape, Blanchard Marc, Juhin Amélie, Rueff Jean-Pascal, Ducher Manoj, Morin Guillaume i Cabaret Delphine. "Local environment of arsenic in sulfide minerals: insights from high-resolution X-ray spectroscopies, and first-principles calculations at the As K-edge". Journal of Analytical Atomic Spectrometry 33, nr 12 (2018): 2070–82. http://dx.doi.org/10.1039/c8ja00272j.

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To improve our knowledge of arsenic local environment in sulfide minerals, Resonant Inelastic X-Ray Scattering (RIXS) maps and High-Energy Resolution Fluorescence Detected (HERFD) XANES measurements are performed at the As K-edge. In addition, the spectra are compared to XANES modelled through first-principles calculations.

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Kawata, H. "Site-specific magnetic XANES". Acta Crystallographica Section A Foundations of Crystallography 49, s1 (21.08.1993): c22. http://dx.doi.org/10.1107/s0108767378099365.

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Rehr, J. J., S. I. Zabinsky, A. Ankudinov i R. C. Albers. "Atomic-XAFS and XANES". Physica B: Condensed Matter 208-209 (marzec 1995): 23–26. http://dx.doi.org/10.1016/0921-4526(94)00623-4.

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Vvedensky, D. D., i J. B. Pendry. "Fast xanes perturbation schemes". Surface Science Letters 152-153 (kwiecień 1985): A107. http://dx.doi.org/10.1016/0167-2584(85)90067-2.

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Vvedensky, D. D., i J. B. Pendry. "Fast XANES perturbation schemes". Surface Science 152-153 (kwiecień 1985): 33–37. http://dx.doi.org/10.1016/0039-6028(85)90122-0.

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ASATURIAN, R. A. "XANES AND EPR SPECTROSCOPIC PROOFS FOR EXISTENCE OF PAIRING HOLES IN HIGH-Tc SUPERCONDUCTORS". Modern Physics Letters B 07, nr 04 (20.02.1993): 243–50. http://dx.doi.org/10.1142/s0217984993000254.

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XANES and EPR spectra data are presented which prove the existence of holes with 3d9L configuration in YBa 2 Cu 3 O 7 − δ at 293 K. With a growth of concentration of these holes, the absorption intensity in XANES spectra near the absorption of the formally trivalent copper at T < T c grows with the increase of T c . When this absorption appears in XANES spectra at T < T c , disappearance of EPR signal is observed under the same conditions. Such absorption is also observed in the bismuth ceramics at T < T c . The data obtained prove that pairing holes make a contribution to this absorption.

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TOMBOLINI, F., A. MARCELLI, A. MOTTANA, G. CIBIN, M. F. BRIGATTI i G. GIULI. "CRYSTAL-CHEMICAL STUDY BY XANES OF TRIOCTAHEDRAL MICAS: THE MOST CHARACTERISTIC LAYER SILICATES". International Journal of Modern Physics B 16, nr 11n12 (20.05.2002): 1673–79. http://dx.doi.org/10.1142/s0217979202011081.

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A crystal-chemical study of trioctahedral micas previously characterized by single-crystal XRD has been performed by XANES spectroscopy at the Si and Al K edges. XANES, being a local structural probe, can investigate distortion and modification of the tetrahedral sheet with increasing Fe for Mg substitution in the octahedral sheet. Comparison of XANES spectra allows determining the size of the tetrahedral site occupied by either Si or Al. The Si-O distance remains essentially unchanged whereas the Al-O distance appears to increase. The behavior may be interpreted as a tilt of the tetrahedra, initially rotated to match the ideal mica geometry, with increasing Fe substitution in the octahedral sheet.

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Roesch, Philipp, Christian Vogel, Thomas Huthwelker, Philipp Wittwer i Franz-Georg Simon. "Investigation of per- and polyfluoroalkyl substances (PFAS) in soils and sewage sludges by fluorine K-edge XANES spectroscopy and combustion ion chromatography". Environmental Science and Pollution Research 29, nr 18 (3.12.2021): 26889–99. http://dx.doi.org/10.1007/s11356-021-17838-z.

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AbstractFor the first time, fluorine K-edge X-ray absorption near-edge structure (XANES) spectroscopy was applied to detect per- and polyfluoroalkyl substances (PFAS) in various soil and sewage sludge samples. The method can be used to determine the speciation of inorganic and organic fluorides, without pre-treatment of solid samples. Therefore, XANES spectra of several inorganic fluorides as well as selected fluorinated organic compounds were recorded. While inorganic fluorides partially exhibit a variety of sharp spectral features in the XANES spectrum, almost all inspected organofluorine compounds show two distinct broad features at 688.5 and 692.0 eV. Moreover, the peak intensity ratio 688.5 eV/692.0 eV in the PFAS XANES spectrum can be inversely correlated to the chain length of the perfluoro sulfonic acid group. The detection of targeted PFAS by bulk-XANES spectroscopy in combination with linear combination fitting in soils and sewage sludges was not applicable due to the low organic fluorine to total fluorine ratio of the samples (0.01–1.84%). Nonetheless, direct analysis of pure PFAS revealed that analysis of organofluorine species might be achieved in higher concentrated samples. Furthermore, quantitative measurements by combustion ion chromatography (CIC) evaluated as sum parameters extractable organically bound fluorine (EOF) and total fluorine (TF) emphasize that besides soils, sewage sludges are a significant source of organic fluorine in agriculture (154–7209 µg/kg).

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Etschmann, Barbara E., Erica Donner, Joël Brugger, Daryl L. Howard, Martin D. de Jonge, David Paterson, Ravi Naidu, Kirk G. Scheckel, Chris G. Ryan i Enzo Lombi. "Speciation mapping of environmental samples using XANES imaging". Environmental Chemistry 11, nr 3 (2014): 341. http://dx.doi.org/10.1071/en13189.

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Environmental context Recently developed fast fluorescence detectors have opened the way to the development of element speciation mapping, i.e. X-ray absorption near edge spectroscopy (XANES) imaging, of environmental samples. This technique is potentially very informative but is also highly data intensive. Here, we used XANES imaging to explore the distribution of Cu species in biosolid materials, destined for agricultural use, as this is of importance in relation to the bioavailability and potential toxicity of this metal. Abstract Fast X-ray detectors with large solid angles and high dynamic ranges open the door to XANES imaging, in which millions of spectra are collected to image the speciation of metals at micrometre resolution, over areas up to several square centimetres. This paper explores how such multispectral datasets can be analysed in order to provide further insights into the distribution of Cu species in fresh and stockpiled biosolids. The approach demonstrated uses Principal Components Analysis to extract the ‘significant’ spectral information from the XANES maps, followed by cluster analysis to locate regions of contrasting spectral signatures. Following this model-free analysis, pixel-by-pixel linear combination fits are used to provide a direct link between bulk and imaging XANES spectroscopy. The results indicate that both the speciation and distribution of Cu species are significantly affected by ageing. The majority of heterogeneously distributed micrometre-sized Cu sulfide particles present in fresh biosolids disappear during the oxidative stockpiling process. In aged biosolids most of the Cu is homogeneously redistributed on organic matter suggesting that Cu mobility is temporarily increased during this redistribution process. This manuscript demonstrates how large XANES imaging datasets could be analysed and used to gain a deep understanding of metal speciation in environmental samples.

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Zhang, Yuanpeng, Osman Ersoy, Ali Karatutlu, William Little i Andrei Sapelkin. "Local structure of Ge quantum dots determined by combined numerical analysis of EXAFS and XANES data". Journal of Synchrotron Radiation 23, nr 1 (1.01.2016): 253–59. http://dx.doi.org/10.1107/s160057751501913x.

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The sensitivity of X-ray absorption near-edge structure (XANES) to the local symmetry has been investigated in small (∼4 nm) matrix-free Ge quantum dots. TheFDMNESpackage was used to calculate the theoretical XANES spectra that were compared with the experimental data of as-prepared and annealed nanoparticles. It was found that XANES data for an as-prepared sample can only be adequately described if the second coordination shell of the diamond-type structural model is included in theFDMNEScalculations. This is in contrast to the extended X-ray absorption fine-structure data that show only the first-shell signal. These results suggest that, despite the high degree of disorder and a large surface-to-volume ratio, as-prepared small Ge quantum dots retain the diamond-type symmetry beyond the first shell. Furthermore, we utilized this sensitivity of XANES to the local symmetry to study annealed Ge quantum dots and found evidence for significant structural distortion which we attribute to the existence of surface disorder in the annealed oxygen-free Ge quantum dots.

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Parsons, J. G., M. L. Lopez, H. Castillo-Michel, J. R. Peralta-Videa i J. L. Gardea-Torresdey. "Arsenic Speciation in Biological Samples Using XAS and Mixed Oxidation State Calibration Standards of Inorganic Arsenic". Applied Spectroscopy 63, nr 8 (sierpień 2009): 961–70. http://dx.doi.org/10.1366/000370209788964359.

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The speciation of elements without pre-edge features preformed with X-ray absorption near edge structure (XANES) can lead to problems when the energy difference between two species is small. The speciation of arsenic (As) in plant samples was investigated using the mixtures As2S3/As2O5, As2S3/As2O3, or As2O3/As2O5. The data showed that the energy separation (eV) between As2O5 and As2S3 was 5.8, between As2O3 and As2O5 was 3.6, and between As2S3 and As2O3 was 2.1. From the intensity of the white-line feature and the concentration of As species, calibration curves showing a limit of detection of approximately 10% were generated. In addition, an error of ±10% was determined for the linear combination–XANES (LC-XANES) fitting technique. The difference between the LC-XANES fittings and calculations from the calibration curves was <10%. The data also showed that the speciation of As in a sample can be determined using EXAFS (extended X-ray absorption fine structure). Finally, it was also shown that both EXAFS and XANES of the sample should be examined to determine the true speciation of an element. Even though there is a difference of 2 eV between As(III) bound to O and As(III) bound to S, in the EXAFS region the As(III)–S and As(III)–O ligands are clearly visible. However, distinction between the As(III)–O and As(V)–O ligands in the EXAFS spectra was not clearly visible in this study.

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Манякин, М. Д., С. И. Курганский, О. И. Дубровский, О. А. Чувенкова, Э. П. Домашевская i С. Ю. Турищев. "Ab initio моделирование и синхротронные рентгеноспектральные исследования оксидов олова вблизи Sn L-=SUB=-3-=/SUB=--краев поглощения". Физика твердого тела 58, nr 12 (2016): 2294. http://dx.doi.org/10.21883/ftt.2016.12.43845.235.

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Представлены результаты теоретических и экспериментальных исследований электронно-энергетического строения зоны проводимости оксидов олова. Методом линеаризованных присоединенных плоских волн (ЛППВ) впервые рассчитана тонкая структура вблизи L3-краев поглощения олова (XANES) для монокристаллов металлического олова, монооксида олова, а также тетрагональной и орторомбической фаз диоксида олова. Тонкая структура спектров XANES сопоставлена с особенностями распределения локальной парциальной плотности состояний олова изученных соединений. Проведен совместный анализ результатов моделирования и экспериментальных рентгеновских синхротронных XANES Sn L3-спектров объемных коммерческих образцов металлического олова, оксидов SnO и SnO2. Работа выполнена при поддержке Министерства образования и науки России в рамках государственного задания вузам в сфере научной деятельности на 2014-2016 годы, проекты N 1606, 757, задание N 3.1868.2014/K, при поддержке РФФИ и правительства Воронежской области в рамках научного проекта N 16-42-360612 p\_а.

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Christensen, C. R., J. N. Cutler i D. A. Christensen. "Using X-ray absorption near edge structure (XANES) spectroscopy to determine selenium oxidation states in animal mineral supplements and feeds". Canadian Journal of Animal Science 84, nr 2 (1.06.2004): 171–75. http://dx.doi.org/10.4141/a03-099.

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Synchrotron-based X-ray absorption near edge structure (XANES) spectroscopy is a relatively new technique within the life sciences. XANES has been utilized to identify the location, oxidation state and spatial distribution of heavy metal elements in plants , neurons, blood and DNA, but has not been widely used in the animal sciences. Selenium content in animal feeds is monitored, as both selenium deficiencies and toxicities are associated with physiological disorders. Selenium is available as an animal feed in both inorganic and organic states. The bioavailability of selenium species has been tested in numerous animal trials; however, a simple, non-destructive test for selenium speciation is not available. The objective of this study was to determine whether XANES spectroscopy could be used to determine the selenium oxidation state found in various commercial animal feed products. A comparison of absorption spectra indicated that the animal mineral supplements contained an organoselenium or selenite. The processed animal feeds had a spectral profile similar to that of elemental selenium. Further experiments are necessary to determine the implication of selenium speciation on animal physiology. Key words: Selenium speciation, mineral supplements, ruminants, non-ruminants, synchrotron, XANES, X-ray

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Домашевская, Э. П., А. А. Гуда, А. В. Чернышев i В. Г. Ситников. "Особенности локальной атомной структуры металлических слоев многослойных наноструктур (CoFeZr/SiO-=SUB=-2-=/SUB=-)-=SUB=-32-=/SUB=- и (CoFeZr/a-Si)-=SUB=-40-=/SUB=- с различными прослойками". Физика твердого тела 59, nr 2 (2017): 373. http://dx.doi.org/10.21883/ftt.2017.02.44065.296.

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Многослойные наноструктуры (МНС) получали путем ионно-лучевого напыления в атмосфере аргона на поверхность вращающейся ситалловой подложки последовательно из двух мишеней, одна из которых была металлическая пластина сплава Co45Fe45Zr10, а второй мишенью была пластина из кварца (SiO2) или кремния. Тонкая структура рентгеновских спектров поглощения XANES вблизи K-краев Co и Fe в образце (CoFeZr/SiO2)32 с оксидными прослойками подобна XANES металлической фольги Fe. Это указывает на наличие в металлических слоях МНС нанокристаллов CoFeZr с локальным окружением, аналогичным локальному окружению атомов в твердых растворах на основе ОЦК структуры Fe, что подтверждается также данными XRD. XANES вблизи K-краев поглощения Co и Fe в другой МНС с кремниевыми прослойками (CoFeZr/a-Si)40 отличается от XANES МНС с диэлектрической прослойкой SiO2, что свидетельствует о преобладающем влиянии связей Fe-Si и Co-Si в локальном окружении 3d-металлов Co и Fe при образовании ими силицидных фаз типа CoFeSi в более тонких бислоях этой МНС. Работа выполнена при поддержке Минобрнауки России в рамках государственного задания вузам в сфере научной деятельности на 2014-2016 годы. Проект N 757 и Задание N 3.1868.2014/K, а также в рамках гранта Президента РФ для молодых ученых МК-7300.2016.2 А.А. Гуда. DOI: 10.21883/FTT.2017.02.44065.296

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Takaoka, M., T. Yamamoto, S. Fujiwara, K. Oshita, N. Takeda, T. Tanaka i T. Uruga. "Chemical states of trace elements in sewage sludge incineration ash by using x-ray absorption fine structure". Water Science and Technology 57, nr 3 (1.02.2008): 411–17. http://dx.doi.org/10.2166/wst.2008.025.

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In this study, the chemical states of chromium (Cr), arsenic (As), and selenium (Se) in sewage sludge incineration ash were determined by X-ray absorption fine structure (XAFS) spectroscopy. Sewage sludge incineration ash was sampled from several facilities, and XAFS measurements were carried out with a beam line BL01B1 at the SPring-8 facility. Cr K-edge X-ray absorption near-edge structure (XANES) spectra suggested that Cr compounds were predominantly speciated as Cr(III) and the fraction of Cr(VI) was very minor. Compared to the reference materials, Cr XANES spectra of the incineration ashes were similar to those of FeCr2O4, Cr(OH)3, and CaCr2O4. As K-edge XANES spectra indicated that As(V) compounds were present in incineration ashes. Because the chemical state of As in sewage sludge was As3 + in our previous study, we speculated that the chemical state of As changed into As(V) during the incineration process. According to Se K-edge XANES spectra, Se compounds were predominantly Se(IV), and a slight difference was observed in the chemical states amongst facilities using inorganic or organic coagulants in the dewatering process.

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Budi, Hariyanto, Husain Husain, Lapboonruang Supanun i Pratapa Suminar. "Examination of Natural and Standard Fe₃O₄ Powders Using X-Ray Absorption Near-Edge Spectroscopy (XANES)". Materials Science Forum 964 (lipiec 2019): 40–44. http://dx.doi.org/10.4028/www.scientific.net/msf.964.40.

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Investigation of Fe K-edge X-Ray Absorption Near Edge Spectroscopy (XANES) spectra of Fe3O4 (FeO.Fe2O3) from natural source compared with the Fe3O4 standard is presented. The natural Fe3O4 powder was prepared from ironstone of Tanah Laut, Kalimantan Selatan by co-precipitation method. XANES measurements in transmission mode were performed at the Synchrotron Light Research Institute (SLRI), Nakhon Ratchasima, Thailand. XRD phase analysis confirms that the synthesized Fe3O4 powder is a single phase, but it cannot determine the proportion of Fe2O3 and FeO in the structure. TEM measurement confirms that the particle size of natural Fe3O4 about 10 nm. Qualitative analysis of the pre-edge XANES data revealed that the absorbing atom in the XAS measurement is Fe3+. Meanwhile, the absorption edge (E0) values of natural and standard Fe3O4 powders were 7126.44 eV and 7125.02 eV, respectively. The proportion was then acquired using XANES data analysis through Linear Combination Fitting (LCF). It was found that the natural Fe3O4 sample consisted of 98 wt. % Fe2O3 and 2 wt.% FeO, while the standard Fe3O4 powder consisted of 96 wt. % Fe2O3 and 4 wt. % FeO. The mechanism of the absorption in both samples is also described and compared.

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Diacomanolis, Violet, Barry N. Noller, Raijeli Taga, Hugh H. Harris, Jade B. Aitken i Jack C. Ng. "Relationship of arsenic speciation and bioavailability in mine wastes for human health risk assessment". Environmental Chemistry 13, nr 4 (2016): 641. http://dx.doi.org/10.1071/en14152.

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Environmental context X-ray absorption near-edge spectroscopy (XANES) was applied to give arsenic chemical forms directly in the solid phase of mine wastes from two mine sites, including fluvial dispersion. The arsenic speciation data explained the variation of in vitro bioaccessibility and in vivo bioavailability (rat uptake) data of the mine wastes. The As speciation from XANES fitting supported the hypothesis that when soil intake is adjusted for bioaccessibility, the potential health risk estimate to local residents is significantly lower. Abstract X-ray absorption near-edge spectroscopy (XANES) was used for arsenic speciation in mine processing and waste samples from two mines in northern Australia. XANES fitting of model compound spectra to samples was used, in combination with in vitro bioaccessibility data for the pure compounds, to predict bioaccessibility of each mine waste sample (Pearson’s correlation R2=0.756, n=51). The XANES fitting data for a smaller set of the samples (n=12) were compared with in vivo bioavailability and in vitro bioaccessibility data. The bioavailability of arsenic (As) in the mine wastes, which is dependent, at least in part, on its oxidation state, was found to be <14% (0.9–13.5%) for arsenite (AsIII) and <17% (3.5–16.4) for arsenate (AsV). Arsenic bioaccessibility in the mine wastes ranged from 8–36% in the stomach to 1–16% in the intestinal phase, indicating that a small portion of the total As concentration in the mine waste was available for absorption. A significant correlation showed that bioaccessibility can be used as a predictor of bioavailability. The XANES results support that bioavailability and bioaccessibility results were very similar and show a strong association with the presence of ferric arsenate and As sulfides. It can be concluded that, when soil intake is adjusted for bioaccessibility, the potential health risk estimate to local residents exposed to the mine waste was significantly lower than that estimated based on a 100% bioavailability often employed for the risk assessment.

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Martin, R. R., S. J. Naftel, T. K. Sham, B. Hart i M. A. Powell. "XANES of chromium in sludges used as soil ameliorants". Canadian Journal of Chemistry 81, nr 2 (1.02.2003): 193–96. http://dx.doi.org/10.1139/v03-013.

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Samples of sewage sludges proposed for use as soil ameliorants in an Indo-Canadian project were tested for chromium content. Standard aqua regia extractions found one sludge to have excessive amounts of Cr. X-ray absorption near-edge structure (XANES) spectroscopy, however, indicated that the Cr was present in the relatively benign Cr(III) oxidation state in all the sludge samples.Key words: soil, chromium, synchrotron, XANES.

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Taweepreda, Wirach, Wanwisa Limphirat i Prayoon Songsiriritthigul. "Oxidative Degradation Monitoring of Natural Rubber Using S K-Edge X-Ray Absorption near-Edge Spectroscopy (XANES)". Advanced Materials Research 620 (grudzień 2012): 440–45. http://dx.doi.org/10.4028/www.scientific.net/amr.620.440.

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In this work, we present the results of sulfur crosslinking and degradation in natural rubber (NR) studied by X-ray absorption near-edge structure spectroscopy (XANES). Sulfur K-edge XANES spectra has been collected and analyzed to provide the geometry and electronic environment of sulfur crosslinks during vulcanization and degradation processes by ozone aging. We found that reversion took place before the onset of oxidative process at the sulfur bridge. Parallel to the oxidative process, the production of cyclic sulfanes took places. This physico-chemical properties which were calculated from S K-edge XANES spectra were correlated with the mechanical of NR films by varying accelerator type. The accelerator zinc diethyldithiocarbamate (ZDEC) gave highest film strength when compared with other accelerators: N-cyclohexylbenzothiazole sulfenamide (CBS), 2,2' dibenzothiazyl disulfide (MBTS), and tetramethylthiuram disulfide (TMTD).

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Zhou, Jigang, Xingtai Zhou, Xuhui Sun, Michael Murphy, Franziskus Heigl, Tsun-Kong Sham i Zhifeng Ding. "Electronic structures of CdSe nanocrystals — An X-ray absorption near-edge structure (XANES) investigation". Canadian Journal of Chemistry 85, nr 10 (1.10.2007): 756–60. http://dx.doi.org/10.1139/v07-080.

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CdSe nanocrystals (NCs), capped with trioctylphosphine oxide and 1-octadecanamine, have been synthesized with colloidal methods. Both UV–vis absorption and photoluminescence spectra show that the prepared nanostructures exhibit a quantum confinement effect. X-ray absorption near–edge structure (XANES) at Se K-edge recorded in fluorescence yield mode have been carried out on these NCs, with different size and capping ligands to gain insight into how their electronic structures are affected by the NC size and chemical properties of the ligands. The results indicate that XANES are sensitive to both the NC size and the nature of the capping ligands. The whiteline intensity in XANES spectra can be related to the photoluminescence properties of these NCs.Key words: CdSe nanocrystals, capping ligands, X-ray absorption near-edge structure, UV–vis spectroscopy, photoluminescence.

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Boesenberg, Ulrike, Christopher G. Ryan, Robin Kirkham, Andreas Jahn, Anders Madsen, Gareth Moorhead, Gerald Falkenberg i Jan Garrevoet. "Fast XANES fluorescence imaging using a Maia detector". Journal of Synchrotron Radiation 25, nr 3 (25.04.2018): 892–98. http://dx.doi.org/10.1107/s1600577518004940.

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A new fast X-ray absorption spectroscopy scanning method was recently implemented at the Hard X-ray Microprobe endstation P06, PETRA III, DESY, utilizing a Maia detector. Spectromicroscopy maps were acquired with spectra for X-ray absorption near-edge structure (XANES) acquisition in the sub-second regime. The method combines XANES measurements with raster-scanning of the sample through the focused beam. The order of the scanning sequence of the axes, one beam energy axis and two (or more) spatial axes, is a variable experimental parameter and, depending on it, the dwell at each location can be either single and continuous (if the energy axis is the inner loop) or in shorter discontinuous intervals (if a spatial axis is innermost). The combination of improved spatial and temporal resolution may be necessary for rapidly changing samples,e.g.for followingin operandochemical reactions or samples highly susceptible to beam damage where the rapid collection of single XANES spectra avoids issues with the emergence of chemical changes developing from latent damage. This paper compares data sets collected on a specially designed test pattern and a geological thin-section scanning the energy as inner, middle and outer axis in the sequence. The XANES data of all three scanning schemes is found to show excellent agreement down to the single-pixel level.

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Takahashi, Y., G. R. Kolonin, G. P. Shironosova, I. I. Kupriyanova, T. Uruga i H. Shimizu. "Determination of the Eu(II)/Eu(III) ratios in minerals by X-ray absorption near-edge structure (XANES) and its application to hydrothermal deposits". Mineralogical Magazine 69, nr 2 (kwiecień 2005): 179–90. http://dx.doi.org/10.1180/0026461056920245.

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AbstractEuropium LIII-edge X-ray absorption near-edge structure (XANES) was employed to determine the Eu(II)/Eu(III) ratios in minerals. This ratio can be determined based on the peak-area ratio of white lines, the resonance peak, in normalized XANES spectra for Eu(II) and Eu(III) species. For precise determination of the Eu(II)/Eu(III) ratios, however, it was revealed that the transition probabilities for each individual Eu(II) and Eu(III) species in the system must be quantified, because we found that the peak area in normalized XANES spectra is different in each Eu(II) and Eu(III) species. Despite this ambiguity, the method was applied to Eu in natural hydrothermal apatites (Eu = 39 and 64 ppm) and fluocerite (Eu = 282 ppm). The relationship between the Eu(II)/Eu(III) ratio in these hydrothermal minerals, and the distribution coefficients of Eu(II) and Eu(III) were discussed, taking into account Eu anomalies in their REE patterns. It is considered that by combining the Eu(II)/Eu(III) ratios determined by XANES and the degree of Eu anomaly in REE patterns, we can provide new information on the distribution of Eu(II) and Eu(III) in various geochemical studies.

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Situm, Arthur, Xiaoxuan Guo, Burke C. Barlow, Bao Guo, Ian J. Burgess i Andrew P. Grosvenor. "A Study of the Corrosion of Polymethyl Methacrylate Coated Rebar Using Glancing Angle X-Ray Absorption Near Edge Spectroscopy". Corrosion 77, nr 12 (29.09.2021): 1291–98. http://dx.doi.org/10.5006/3912.

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Polymer coatings can be used to mitigate the corrosion of steel in high-chloride environments. Obtaining speciation information from thin corrosion layers can be important for understanding corrosion mechanisms, including polymer coating failure. This study outlines the effectiveness of collecting glancing angle x-ray absorption near edge spectroscopy (GA-XANES) spectra at the Fe K-edge to obtain chemical speciation information at the polymer/steel interface without removal of the polymer film. The depth of penetration of the incident x rays can be altered by changing the incidence angle, allowing for more fluorescence signal from corrosion products to be detected relative to the Fe metal fluorescence signal in GA-XANES spectra. This study demonstrates the use of GA-XANES to study thin layers of steel corrosion and obtain depth profile information of steel corrosion products beneath a polymethyl methacrylate polymer coating.

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