Application Of X-ray Absorption Spectroscopy Research Articles

Iterative Bragg peak removal on X-ray absorption spectra with automatic intensity correction.

This study introduces a novel iterative Bragg peak removal with automatic intensity correction (IBR-AIC) methodology for X-ray absorption spectroscopy (XAS), specifically addressing the challenge of Bragg peak interference in the analysis of crystalline materials. The approach integrates experimental adjustments and sophisticated post-processing, including an iterative algorithm for robust calculation of the scaling factor of the absorption coefficients and efficient elimination of the Bragg peaks, a common obstacle in accurately interpreting XAS data, particularly in crystalline samples. The method was thoroughly evaluated on dilute catalysts and thin films, with fluorescence mode and large-angle rotation. The results underscore the technique's effectiveness, adaptability and substantial potential in improving the precision of XAS data analysis. While demonstrating significant promise, the method does have limitations related to signal-to-noise ratio sensitivity and the necessity for meticulous angle selection during experimentation. Overall, IBR-AIC represents a significant advancement in XAS, offering a pragmatic solution to Bragg peak contamination challenges, thereby expanding the applications of XAS in understanding complex materials under diverse experimental conditions.

Application of X-ray absorption spectroscopy in carbon-supported electrocatalysts

Application of X-ray absorption spectroscopy in carbon-supported electrocatalysts

Recent Applications of X-ray Absorption Spectroscopy in Combination with High Energy Resolution Fluorescence Detection

X-ray absorption spectroscopy (XAS) has grown as one of the essential tools to analyze electronic and geometric structure of a target element in chemistry over the course of a half-century. X-ray e...

Operando X-ray absorption spectroscopy applied to battery materials at ICGM: The challenging case of BiSb's sodiation

X-ray absorption spectroscopy (XAS) is a synchrotron-based, element-specific, short-range structural method largely used in the study of materials, already widely employed for the study of the electrochemical processes in battery systems. The high penetration of the X-rays makes XAS particularly suited for the study of battery materials under operando conditions using specifically developed in situ electrochemical cells. In this paper, the application of XAS to the study of battery materials carried out at Institut Charles Gerhardt Montpellier (France) will be outlined, illustrating the type of information provided by XAS. The challenging study of the sodiation of Bi0.50Sb0.50 followed individually and simultaneously at both metals will be also presented in order to highlight the typical advantages of this technique even when it is pushed at its technical limits.

Application of X-ray absorption spectroscopy for L3-edges of Dy and Yb in dibenzoylmethanide complexes: Experiment and theoretical interpretation

Local atomic and electronic structure of Dy- and Yb-based dibenzoylmethanide complexes has been investigated by analysis of experimental and theoretical L3-edge XANES spectra. The local atomic structure similarity between recrystallized and as-synthesized samples has been proved by XANES. Differences in the experimental XANES spectra collected for a Ln-complexes with a different ligand ratio (dbm-): (O-btd-) have been observed and assigned with a higher abundancy of elongated Ln-N bonds with respect to Ln-O for the sample where Ln-ions coordinated by higher number of O-btd- ligands. In this work we also critically discussed XANES simulations based on monoelectronic approach as implemented in FDMNES code for L3-edge spectra calculated for Ln-complexes. Density of electronic state calculation has been performed in order to elucidate the origin of the XANES features. Since the product yield of as-synthesized Ln-complexes is significantly higher rather than after re-crystallization this work demonstrate a high potential of DFT-assisted XANES analysis for the structural investigation of as-synthesized complexes without long-range atomic ordering.

Probe active sites of heterogeneous electrocatalysts by X-ray absorption spectroscopy: From single atom to complex multi-element composites

Abstract As the design of heterogeneous electrocatalysts is entering the ‘atom’ age, synchrotron radiation-based X-ray absorption spectroscopy (XAS) has started to expand its strategic presence in electrocatalysis. XAS has demonstrated its usefulness in determining the electronic and geometric structures of supported single atom catalysts thanks to its high sensitivities towards elemental, chemical, and orbital determination. Nowadays, it is expected that the role of XAS will further increase as current research interests are shifting to more complex size-selected single- or multi-element atomic clusters, including challenging electrochemical processes. This review discusses the latest applications of XAS in characterization of electrocatalysts with atomic dispersion, such as single atoms and clusters. Involved advanced analyses methods like wavelet transform, as well as outlooks and challenges for revealing the dynamic behaviours of catalytic active sites using in-situ XAS are also presented and discussed.

Application of x-ray absorption spectroscopy on local structure study in Fe-doped BaTiO3 ceramics

ABSTRACTIn this work, Fe-doped BaTiO3 ceramics were prepared by a conventional solid state reaction method. The effects of sintering temperature on the global and local structures of Fe-doped BaTiO3 ceramic (with 10 mole% Fe) were investigated by X-ray diffraction (XRD) and X-ray Absorption Spectroscopy (XAS) techniques, respectively. The XRD measurements indicated the global structure of the prepared ceramic changed from pure tetragonal to hexagonal structure with increasing sintering temperature. From Synchrotron X-ray Absorption Near-Edge Structure (XANES) measurements, the oxidation state of Fe ions in BaTiO3 structure was clearly identified, as +3. The clear agreement between the experimental and theoretical XANES spectra indicated Fe substituting on Ti site in BaTiO3 structure.

Application of X-ray absorption spectroscopy in the study of environmental radiochemistry of actinides

Application of X-ray absorption spectroscopy in the study of environmental radiochemistry of actinides

X-ray absorption spectroscopy studies in supercritical aqueous solutions

ABSTRACTThe past two decades have witnessed significant advances in the application of X-ray absorption spectroscopy (XAS) to the study of supercritical aqueous fluids. The data obtained using in situ XAS have provided insights into the stability and the structure of metal complexes that are fundamental to understanding natural and industrial hydrothermal processes. Important recent advances using XAS can be attributed to the use of new high temperature and pressure autoclaves designed specifically for the analysis of fluids at extreme temperatures and pressures, improved techniques for the acquisition of X-ray absorption spectra and molecular-level computational modelling used in association with XAS analysis. High-brilliance light sources have not only provided new opportunities for XAS investigations of supercritical fluids, but have also revealed the effects of beam-induced radiolysis of the same fluids. The advent of energy-dispersive and rapid-acquisition XAS holds promise for future studies of beam-induced radiolysis and of the kinetics associated with the formation of metal complexes in high-temperature fluids.

The application of X-ray absorption spectroscopy in archaeological conservation: Example of an artefact from Henry VIII warship, the Mary Rose

We report a microfocus X-ray absorption (XAS) investigation of a thin film sample from an iron contaminated wooden arrow tip raised from the seabed with the Mary Rose. The XAS studies were combined with optical and scanning electron microscopy measurements. The arrow tip had been treated with polyethylene glycol (PEG) soon after it had been raised and stored in a controlled environment. The measurements revealed a significant concentration of iron sulfide nanoparticles. This indicates that in this sample there was a reduction of the oxidative effects of the normal ambient atmosphere that is usually seen in untreated timbers. The film was treated overnight with an aqueous solution of diethylenetriaminepentaacetic acid (DTPA), which is normally very effective in sequestering iron. This had little effect in terms of removing iron from the film and possible explanations are discussed.

Recent XAS studies into Homogeneous metal catalyst in fine chemical and pharmaceutical syntheses.

A brief review of studies using X-ray Absorption Spectroscopy (XAS) to investigate homogeneous catalytic reactions in fine chemical and pharmaceutical context since 2010 is presented. The advantages of the techniques over traditional lab-based analytical tools, particularly when NMR spectroscopy fails to deliver mechanistic insights, are summarised using these examples. A discussion on the current limitations of the techniques and challenges in the near future is also included.Graphical abstractA minireview of recent developments in application of X-ray Absorption Spectroscopy as an effective mechanistic tool to synthetic catalytic reactions relevant to fine chemical and pharmaceutical syntheses.

Application of X-ray Absorption Spectroscopy (XAS) in the Field of Stabilization of As and Heavy Metal Contaminated Soil

X-ray absorption fine structure (XAFS) analysis using X-ray absorption spectroscopy is being applied as a state-of-the- art method in a wide range of disciplines. This review article summarizes the overall procedure of XAFS analysis from the preparation of soil samples to the analysis of data in X-ray absorption near edge structure (XANES) region and extended X- ray absorption fine structure (EXAFS) region. The previous studies on application of XANES and EXAFS techniques in environmental soil science field are discussed and classified them according to metal(loid)s (As, Cd, Cu, Ni, Pb, and Zn). A significant number of previous studies of XAFS application in the environmental soil science field have focused on the identification of Pb chemical species in soil. Moreover, XANES and EXAFS techniques have been widely used to investigate the contamination source via identification of metal species. Similarly, these techniques were applied to identify the mechanisms of metal stabilization in soil after application of various amendments, phytoremediation, etc.

Chromium Speciation in Solid Waste Material and Eluates by X-Ray Absorption Spectroscopy and Ion Chromatography

The tremendous generation of solid waste material is a worldwide problem. Apart from avoidance of waste materials, their reuse is a main goal of modern waste management. Reuse of waste materials demands adequate risk assessment and reliable quantification methods considering the release potential of harmful compounds. In this context, due to its cancerogenity, hexavalent chromium (Cr(VI)) is of high ecotoxicological, human toxicological and environmental relevance. In this contribution, we focus on the speciation of chromium in two representative solid waste materials (demolition waste material, DWM; municipal waste incineration product, MWIP) and eluates obtained after leaching. For chromium speciation, X-ray absorption spectroscopy (XAS) and ion chromatography coupled with inductively coupled plasma optical emission spectrometry (IC/ICP-OES) were applied. It could be observed that in spite of relatively low contents of Cr(VI) in both solid materials (DWM: 16 ± 1 mg/kg, MWIP: 67 ± 5; aqua regia digestion), environmentally relevant concentrations of Cr(VI) were released from the materials as revealed by batch and column leaching experiments. In particular, threshold values for Cr(VI) of the German Federal Soil Protection and Contaminated Sites Ordinance were significantly exceeded. Application of XAS allowed both the determination of mobilizable Cr(VI) directly in the solid materials and in the alkaline eluates, even at concentrations below 500 µg/L. The results obtained were in agreement with data of leaching tests and with IC/ICP-OES measurements. IC/ICP-OES enabled a rapid, well-reproducible and sensitive quantification of Cr(VI) in the eluates in the lower µg/L range. The presented combination of independent analytical methods and mutual validation is highly powerful and is a valuable contribution for risk assessment of waste material. The principle of the approach can be used for the investigation of other solid materials and elements and their assessment.

ChemInform Abstract: Critical Review: Effects of Complex Interactions on Structure and Dynamics of Supported Metal Catalysts

AbstractReview: 275 refs.

Application of X-ray absorption spectroscopy to the investigation of charge states of iron ions in iron borate nanoceramics

The method of X-ray absorption spectroscopy has been used for the investigation of charge states of iron ions in iron borate nanoceramics prepared by shear deformation under pressure. The experimental Fe 2p X-ray absorption spectra have been presented in comparison with the calculation of atomic multiplets of iron ions taking into account the charge transfer from the 2p orbitals of oxygen to the 3d orbitals of iron and the crystal-field splitting of the 3d orbitals of iron. Our results indicate that, in addition to iron ions in the ground charge state Fe3+, nanostructured FeBO3 contains a few percent of Fe2+ ions. It has been found that an increase in the degree of plastic deformation (the rotation angle of the anvils) leads to a decrease in the size of crystallites and to an increase in the concentration of Fe2+ ions without the formation of new phases. The results of this work agree with the magnetic and optical measurements and confirm high defectness of FeBO3 nanoceramics.

Application of X-ray absorption spectroscopy and molecular dynamics simulation to study the atomistic solvation structure of tetraglyme:KSCN electrolytes

The atomistic solvation structure of tetraglyme:KSCN (TET:KSCN) electrolytes with various K+:ether oxygen (M:O) ratio were studied by a combination of molecular dynamic (MD) simulation and Extended X-Ray Absorption Fine Structure (EXAFS) called “MD-EXAFS” method. This method gives useful information at the atomistic scale including the average distance between atom pair around the probed ion (R0) and Coordination Number (N). MD simulation results suggest that K+ ions are mostly coordinated to ether oxygen and the conformation around C–C bond prefer the gauche state and TET becomes more compact shape. K+ ions are also coordinated to thiocyanate (SCN−) anion at both nitrogen and sulfur atoms due to strong electron delocalization over three atoms in SCN− (S, C and N). A comparison between MD-EXAFS with the experimental spectra gives an overall good agreement for both frequency and amplitude of the oscillations.

Critical review: Effects of complex interactions on structure and dynamics of supported metal catalysts

This review article takes a new look at the problem of characterization of structural properties and reaction dynamics of supported metal catalysts. Such catalysts exhibit an inherent complexity, particularly due to interactions with the support and the adsorbate molecules, which can be highly sensitive to environmental conditions such as pressure and temperature. Recent reports demonstrate that finite size effects such as negative thermal expansion and large bond length disorder are directly caused by these complex interactions. To uncover the atomistic features underlying the reaction mechanisms and kinetics of metal catalysts, experimental characterization must accommodate the challenging operation conditions of catalytic processes and provide insights into system attributes. The combined application of x-ray absorption spectroscopy (XAS) and transmission electron microscopy (TEM) for this type of investigations will be examined, and the individual strengths and limitations of these methods will be discussed. Furthermore, spatial and temporal heterogeneities that describe real catalytic systems and can hinder their investigation by either averaging (such as XAS) or local (such as TEM) techniques alone will be addressed by conjoined, multiscale, ab initio density functional theory/molecular dynamics modeling of metal catalysts that can both support and guide experimental studies. When taken together, a new analysis scheme emerges, in which different forms of structure and dynamics can be fully characterized by combining information obtained experimentally by in situ XAS and electron microscopy as well as theoretically via modeling.

Selenium Metabolism in Cancer Cells: The Combined Application of XAS and XFM Techniques to the Problem of Selenium Speciation in Biological Systems

Determining the speciation of selenium in vivo is crucial to understanding the biological activity of this essential element, which is a popular dietary supplement due to its anti-cancer properties. Hyphenated techniques that combine separation and detection methods are traditionally and effectively used in selenium speciation analysis, but require extensive sample preparation that may affect speciation. Synchrotron-based X-ray absorption and fluorescence techniques offer an alternative approach to selenium speciation analysis that requires minimal sample preparation. We present a brief summary of some key HPLC-ICP-MS and ESI-MS/MS studies of the speciation of selenium in cells and rat tissues. We review the results of a top-down approach to selenium speciation in human lung cancer cells that aims to link the speciation and distribution of selenium to its biological activity using a combination of X-ray absorption spectroscopy (XAS) and X-ray fluorescence microscopy (XFM). The results of this approach highlight the distinct fates of selenomethionine, methylselenocysteine and selenite in terms of their speciation and distribution within cells: organic selenium metabolites were widely distributed throughout the cells, whereas inorganic selenium metabolites were compartmentalized and associated with copper. New data from the XFM mapping of electrophoretically-separated cell lysates show the distribution of selenium in the proteins of selenomethionine-treated cells. Future applications of this top-down approach are discussed.

The structure of ion beam amorphised zirconolite studied by grazing angle X-ray absorption spectroscopy

Ti K edge X-ray absorption spectroscopy (XAS) was applied to determine the Ti co-ordination environment in the surface amorphised layer formed on zirconolite ceramics by 2 MeV Kr+ irradiation, to a fluence of 5 × 1015 ions cm−2. The application of XAS in a grazing angle geometry was demonstrated to be essential in order to probe only the surface damaged layer (<1000 nm thick), in isolation of the undamaged interior of the specimen. 2 MeV Kr+ irradiation induced a change in the Ti co-ordination environment from majority six fold to majority five fold in the amorphised surface layer. This finding is consistent with the formation of five fold Ti in metamict natural zirconolite, as reported previously and confirmed in this study, despite the difference in dose rate of at least 1012 between ion beam irradiated and naturally metamict materials. This study therefore opens the door to systematic investigation of composition – structure – property relations in materials designed for radioactive waste immobilisation, through the combined application of ion beam irradiation and grazing angle XAS.

X-ray absorption spectroscopy

This review gives a brief description of the theory and application of X-ray absorption spectroscopy, both X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS), especially, pertaining to photosynthesis. The advantages and limitations of the methods are discussed. Recent advances in extended EXAFS and polarized EXAFS using oriented membranes and single crystals are explained. Developments in theory in understanding the XANES spectra are described. The application of X-ray absorption spectroscopy to the study of the Mn4Ca cluster in Photosystem II is presented.