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Sample records for absorption spectroscopy x-ray

  1. X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yano, Junko; Yachandra, Vittal K.

    2009-07-09

    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.

  2. High-Resolution X-ray Emission and X-ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Groot, F.M.F. de

    2000-01-01

    In this review, high-resolution X-ray emission and X-ray absorption spectroscopy will be discussed. The focus is on the 3d transition-metal systems. To understand high-resolution X-ray emission and reso-nant X-ray emission, it is first necessary to spend some time discussing the X-ray absorption

  3. (EXAFS) X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Craievich, A.F.

    1983-01-01

    The technique EXAFS (Extended X-Ray Absorption Fine Structure) is presented and its applications using the synchrotron radiation as an incidente beam in Science of Materials and Biophysics are shown. (L.C.) [pt

  4. X-ray absorption spectroscopy of semiconductors

    CERN Document Server

    Ridgway, Mark

    2015-01-01

    X-ray Absorption Spectroscopy (XAS) is a powerful technique with which to probe the properties of matter, equally applicable to the solid, liquid and gas phases. Semiconductors are arguably our most technologically-relevant group of materials given they form the basis of the electronic and photonic devices that now so widely permeate almost every aspect of our society. The most effective utilisation of these materials today and tomorrow necessitates a detailed knowledge of their structural and vibrational properties. Through a series of comprehensive reviews, this book demonstrates the versatility of XAS for semiconductor materials analysis and presents important research activities in this ever growing field. A short introduction of the technique, aimed primarily at XAS newcomers, is followed by twenty independent chapters dedicated to distinct groups of materials. Topics span dopants in crystalline semiconductors and disorder in amorphous semiconductors to alloys and nanometric material as well as in-sit...

  5. X-ray absorption spectroscopy (EXAFS)

    International Nuclear Information System (INIS)

    Craievich, A.F.

    1983-01-01

    The experimental technics of Extended X-ray Absorption Fine Structure (EXAFS) is presented and several uses of it in atomic, molecular and bio physics are shown. The recent progresses of this technics, both theoretical and experimental, are discussed and the future perspectives on this subject are commented. (L.C.) [pt

  6. Femtosecond X-ray Absorption Spectroscopy at a Hard X-ray Free Electron Laser

    DEFF Research Database (Denmark)

    Lemke, Henrik T.; Bressler, Christian; Chen, Lin X.

    2013-01-01

    X-ray free electron lasers (XFELs) deliver short (current (SASE based) XFELs, they can be used for measuring high......-quality X-ray absorption data and we report femtosecond time-resolved X-ray absorption near-edge spectroscopy (XANES) measurements of a spin-crossover system, iron(II) tris(2,2'-bipyridine) in water. The data indicate that the low-spin to high-spin transition can be modeled by single-exponential kinetics...

  7. Laser plasma x-ray source for ultrafast time-resolved x-ray absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    L. Miaja-Avila

    2015-03-01

    Full Text Available We describe a laser-driven x-ray plasma source designed for ultrafast x-ray absorption spectroscopy. The source is comprised of a 1 kHz, 20 W, femtosecond pulsed infrared laser and a water target. We present the x-ray spectra as a function of laser energy and pulse duration. Additionally, we investigate the plasma temperature and photon flux as we vary the laser energy. We obtain a 75 μm FWHM x-ray spot size, containing ∼106 photons/s, by focusing the produced x-rays with a polycapillary optic. Since the acquisition of x-ray absorption spectra requires the averaging of measurements from >107 laser pulses, we also present data on the source stability, including single pulse measurements of the x-ray yield and the x-ray spectral shape. In single pulse measurements, the x-ray flux has a measured standard deviation of 8%, where the laser pointing is the main cause of variability. Further, we show that the variability in x-ray spectral shape from single pulses is low, thus justifying the combining of x-rays obtained from different laser pulses into a single spectrum. Finally, we show a static x-ray absorption spectrum of a ferrioxalate solution as detected by a microcalorimeter array. Altogether, our results demonstrate that this water-jet based plasma source is a suitable candidate for laboratory-based time-resolved x-ray absorption spectroscopy experiments.

  8. Characterization of Metalloproteins and Biomaterials by X-ray Absorption Spectroscopy and X-ray Diffraction

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl

    This thesis presents thework on combining complementary X-rays techniques for studying the structures of proteins and other biomaterials, and consists of three different projects: (i) Characterization of protein powders with X-ray powder diffraction (XRPD). (ii) The combination of X-ray...... crystallography and X-ray absorption spectroscopy (XAS) applied to studying different hexameric insulin conformations. (iii) The structures of polymorphs of strontium ranelate and the distribution of strontium in bone tissue. A procedure for fast identification and verification of protein powders using XRPD...... was correction for disordered bulk-solvent, but also correction for background and optimization of unit cell parameters have to be taken into account. A sample holder was designed for collecting powder diffraction data on a standard laboratory X-ray powder diffractometer. The background was reduced by use...

  9. Valence-to-core-detected X-ray absorption spectroscopy

    DEFF Research Database (Denmark)

    Hall, Eleanor R.; Pollock, Christopher J.; Bendix, Jesper

    2014-01-01

    X-ray absorption spectroscopy (XAS) can provide detailed insight into the electronic and geometric structures of transition-metal active sites in metalloproteins and chemical catalysts. However, standard XAS spectra inherently represent an average contribution from the entire coordination...... environment with limited ligand selectivity. To address this limitation, we have investigated the enhancement of XAS features using valence-to-core (VtC)-detected XAS, whereby XAS spectra are measured by monitoring fluorescence from valence-to-core X-ray emission (VtC XES) events. VtC emission corresponds...... to transitions from filled ligand orbitals to the metal 1s core hole, with distinct energetic shifts for ligands of differing ionization potentials. VtC-detected XAS data were obtained from multiple valence emission features for a series of well-characterized Mn model compounds; taken together, these data...

  10. Arsenic speciation in solids using X-ray absorption spectroscopy

    Science.gov (United States)

    Foster, Andrea L.; Kim, Chris S.

    2014-01-01

    Synchrotron-based X-ray absorption spectroscopy (XAS) is an in situ, minimally-destructive, element-specific, molecular-scale structural probe that has been employed to study the chemical forms (species) of arsenic (As) in solid and aqueous phases (including rocks, soils, sediment, synthetic compounds, and numerous types of biota including humans) for more than 20 years. Although several excellent reviews of As geochemistry and As speciation in the environment have been published previously (including recent contributions in this volume), the explosion of As-XAS studies over the past decade (especially studies employing microfocused X-ray beams) warrants this new review of the literature and of data analysis methods.

  11. X-ray Absorption Spectroscopy in Mineralogy: A Review

    International Nuclear Information System (INIS)

    Mottana, Annibale

    2003-01-01

    The number of mineral species known to date rapidly approaches 4000, and yet they represent but a small fraction of all the known inorganic and organic compounds. Nevertheless, minerals represent an ideal field of activity for X-ray absorption spectroscopy (XAS), because the investigation of their crystal-chemical peculiarities takes an enormous advantage of the property of this method of being atom-selective, even in the presence of a wide range of competing atoms located in similar structural environments. As a matter of fact, XAS on minerals proved to be a useful probing method as early as for W. Kossel's pioneer studies of in the 1930's, just after the fine structures occurring at and near the absorption edge had been first detected. However, XAS did not really become consolidated in mineral studies until the 1980's, when synchrotron sources became available to users. A concise, but complete review of the historical and recent applications of XAS to minerals and to their analogues synthesized for geological/geophysical purposes i.e., to better understand the mechanisms by which the Earth evolves, is here given. Special reference will be made to transition metals (Ca, Ti, Cr, Mn, Fe, Ni) which absorb in the hard X-ray spectral region (> 4 KeV) and to the geologically-significant elements (O, Na, Mg, Al, Si, S and K) which absorb in the soft X-ray region (500-4000 eV)

  12. Utilization of synchrotron radiation in analytical chemistry. Soft X-ray emission and absorption spectroscopy

    International Nuclear Information System (INIS)

    Muramatsu, Yasuji

    2015-01-01

    Synchrotron soft X-ray spectroscopy includes three major types of spectroscopy such as X-ray absorption spectroscopy (XAS), X-ray emission spectroscopy (XES), and X-ray photoelectron spectroscopy (XPS). This paper takes up XAS and XES of soft X-rays, and briefly describes the principle. XAS is roughly classified into XANES (X-ray absorption near-edge structure) and EXAFS (extended X-ray absorption fine structure), and XANES is mainly used in the analysis based on XAS of soft X-rays. As the examples of the latest soft X-ray analyses, the following are introduced: (1) bandgap of boron implantation diamond and the local structure of boron, (2) catalytic sites in solid fuel cell carbon electrode, and (3) soft X-ray analysis under atmospheric pressure. (A.O.)

  13. Soft X-ray Absorption Spectroscopy of Liquids and Solutions.

    Science.gov (United States)

    Smith, Jacob W; Saykally, Richard J

    2017-12-13

    X-ray absorption spectroscopy (XAS) is an electronic absorption technique for which the initial state is a deeply buried core level. The photon energies corresponding to such transitions are governed primarily by the binding energies of the initial state. Because the binding energies of core electrons vary significantly among atomic species, this makes XAS an element-selective spectroscopy. Proper interpretation of XA spectra can provide detailed information on the local chemical and geometric environment of the target atom. The introduction of liquid microjet and flow cell technologies into XAS experiments has enabled the general study of liquid samples. Liquids studied to date include water, alcohols, and solutions with relevance to biology and energy technology. This Review summarizes the experimental techniques employed in XAS studies of liquid samples and computational methods used for interpretation of the resulting spectra and summarizes salient experiments and results obtained in the XAS investigations of liquids.

  14. F K-edge soft X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Sugimura, Tetsuro; Kawai, Jun; Maeda, Kuniko; Fukushima, Akiko; Shin, S.; Motoyama, Muneyuki; Nakajima Tsuyoshi

    2001-01-01

    We measured F X-ray absorption spectra of various fluorine compounds using a synchrotron radiation at KEK-PF. The absorption spectra were measured using X-ray fluorescence yield (XFY) and total electron yield (TEY) methods. Change of the spectral shape has a relation to the metal-fluorine bond distance. By comparing with the experimental spectrum and calculated spectrum, F 2p state density is divined into up and down states. (author)

  15. Multiple scattering approach to X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Benfatto, M.; Wu Ziyu

    2003-01-01

    In this paper authors present the state of the art of the theoretical background needed for analyzing X-ray absorption spectra in the whole energy range. The multiple-scattering (MS) theory is presented in detail with some applications on real systems. Authors also describe recent progress in performing geometrical fitting of the XANES (X-ray absorption near-edge structure) energy region and beyond using a full multiple-scattering approach

  16. X-ray Absorption Spectroscopy of the Rare Earth orthophosphates

    International Nuclear Information System (INIS)

    Shuh, D.K.; Terminello, L.J.; Boatner, L.A.; Abraham, M.M.

    1993-06-01

    X-ray Absorption Spectroscopy (XAS) of the Rare Earth (RE) 3d levels yields sharp peaks near the edges as a result of strong, quasi-atomic 3d 10 4f n → 3d- 9 4f n+1 transitions and these transitions exhibit a wealth of spectroscopic features. The XAS measurements of single crystal REPO 4 (RE = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er) at the 3d edge were performed in the total yield mode at beam line 8-2 at the Stanford Synchrotron Radiation Laboratory (SSRL). The XAS spectra of the RE ions in the orthophosphate matrix generally resemble the XAS of the corresponding RE metal. This is not unexpected and emphasizes the major contribution of the trivalent state to the electronic transitions at the RE 3d edges. These spectra unequivocally identify the transitions originating from well-characterized RE cores and correlate well with previous theoretical investigations

  17. A laboratory-based hard x-ray monochromator for high-resolution x-ray emission spectroscopy and x-ray absorption near edge structure measurements

    Energy Technology Data Exchange (ETDEWEB)

    Seidler, G. T., E-mail: seidler@uw.edu; Mortensen, D. R.; Remesnik, A. J.; Pacold, J. I.; Ball, N. A.; Barry, N.; Styczinski, M.; Hoidn, O. R. [Physics Department, University of Washington, Seattle, Washington 98195-1560 (United States)

    2014-11-15

    We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low power x-ray (bremsstrahlung) tube source, a spherically bent crystal analyzer, and an energy-resolving solid-state detector. This relatively inexpensive, introductory level instrument achieves 1-eV energy resolution for photon energies of ∼5 keV to ∼10 keV while also demonstrating a net efficiency previously seen only in laboratory monochromators having much coarser energy resolution. Despite the use of only a compact, air-cooled 10 W x-ray tube, we find count rates for nonresonant x-ray emission spectroscopy comparable to those achieved at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure, the monochromatized flux is small (due to the use of a low-powered x-ray generator) but still useful for routine transmission-mode studies of concentrated samples. These results indicate that upgrading to a standard commercial high-power line-focused x-ray tube or rotating anode x-ray generator would result in monochromatized fluxes of order 10{sup 6}–10{sup 7} photons/s with no loss in energy resolution. This work establishes core technical capabilities for a rejuvenation of laboratory-based hard x-ray spectroscopies that could have special relevance for contemporary research on catalytic or electrical energy storage systems using transition-metal, lanthanide, or noble-metal active species.

  18. Structure and dynamics in liquid water from x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Wernet, Philippe

    2009-01-01

    Oxygen K-edge x-ray absorption spectra of water are discussed. The spectra of gas-phase water, liquid water and ice illustrate the sensitivity of oxygen K-edge x-ray absorption spectroscopy to hydrogen bonding in water. Transmission mode spectra of amorphous and crystalline ice are compared to x-ray Raman spectra of ice. The good agreement consolidates the experimental spectrum of crystalline ice and represents an incentive for theoretical calculations of the oxygen K-edge absorption spectrum of crystalline ice. Time-resolved infrared-pump and x-ray absorption probe results are finally discussed in the light of this structural interpretation.

  19. X-Ray Absorption Spectroscopy of Uranium Dioxide

    Energy Technology Data Exchange (ETDEWEB)

    Tobin, J G

    2010-12-10

    After the CMMD Seminar by Sung Woo Yu on the subject of the x-ray spectroscopy of UO2, there arose some questions concerning the XAS of UO2. These questions can be distilled down to these three issues: (1) The validity of the data; (2) The monchromator energy calibration; and (3) The validity of XAS component of the figure shown. The following will be shown: (1) The data is valid; (2) It is possible to calibrate the monchromator; and (3) The XAS component of the above picture is correct. The remainder of this document is in three sections, corresponding to these three issues.

  20. X-ray absorption spectroscopy using a self-seeded soft X-ray free-electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Kroll, Thomas; Kern, Jan; Kubin, Markus; Ratner, Daniel; Gul, Sheraz; Fuller, Franklin D.; Löchel, Heike; Krzywinski, Jacek; Lutman, Alberto; Ding, Yuantao; Dakovski, Georgi L.; Moeller, Stefan; Turner, Joshua J.; Alonso-Mori, Roberto; Nordlund, Dennis L.; Rehanek, Jens; Weniger, Christian; Firsov, Alexander; Brzhezinskaya, Maria; Chatterjee, Ruchira; Lassalle-Kaiser, Benedikt; Sierra, Raymond G.; Laksmono, Hartawan; Hill, Ethan; Borovik, Andrew; Erko, Alexei; Föhlisch, Alexander; Mitzner, Rolf; Yachandra, Vittal K.; Yano, Junko; Wernet, Philippe; Bergmann, Uwe

    2016-01-01

    © 2016 Optical Society of America. X-ray free electron lasers (XFELs) enable unprecedented new ways to study the electronic structure and dynamics of transition metal systems. L-edge absorption spectroscopy is a powerful technique for such studies and the feasibility of this method at XFELs for solutions and solids has been demonstrated. However, the required x-ray bandwidth is an order of magnitude narrower than that of self-amplified spontaneous emission (SASE), and additional monochromatization is needed. Here we compare L-edge x-ray absorption spectroscopy (XAS) of a prototypical transition metal system based on monochromatizing the SASE radiation of the linac coherent light source (LCLS) with a new technique based on self-seeding of LCLS. We demonstrate how L-edge XAS can be performed using the self-seeding scheme without the need of an additional beam line monochromator. We show how the spectral shape and pulse energy depend on the undulator setup and how this affects the x-ray spectroscopy measurements.

  1. A structural study of ceramic oxides by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Akhtar, M.J.

    1995-01-01

    A detailed structural study of ceramic oxides is presented by employing X-ray Absorption Spectroscopy (XAS). In the present work X-ray Absorption Near Edge Structure (XANES) is used for the investigation of valence state of metal cations; whereas, Extended X-ray Absorption Fine Structure EXAFS) is employed for the determination for bond lengths, coordination numbers and nature of the elements present in the near neighbour shells surrounding the absorbing atom. These results show that local environment of dopant and host cations are different; and this variation in local structure depends on the nature and concentration of the dopant ions. (author)

  2. Synchrotron radiation spectroscopy including X-ray absorption spectroscopy and industrial applications

    International Nuclear Information System (INIS)

    Oshima, Masaharu

    2016-01-01

    Recent trends of synchrotron radiation spectroscopy, especially X-ray absorption spectroscopy for industrial applications are introduced based on our latest results for energy efficient devices such as magnetic RAM, LSI and organic FET, power generation devices such as fuel cells, and energy storage devices such as Li ion batteries. Furthermore, future prospects of spectroscopy with higher energy resolution, higher spatial resolution, higher temporal resolution and operando spectroscopy taking advantage of much brighter synchrotron radiation beam at low emittance SR rings are discussed from the view point of practical applications. (author)

  3. X-ray absorption and X-ray emission spectroscopy theory and applications

    CERN Document Server

    Lamberti, Carlo

    2016-01-01

    During the last two decades, remarkable and often spectacular progress has been made in the methodological and instrumental aspects of x–ray absorption and emission spectroscopy. This progress includes considerable technological improvements in the design and production of detectors especially with the development and expansion of large-scale synchrotron reactors All this has resulted in improved analytical performance and new applications, as well as in the perspective of a dramatic enhancement in the potential of x–ray based analysis techniques for the near future. This comprehensive two-volume treatise features articles that explain the phenomena and describe examples of X–ray absorption and emission applications in several fields, including chemistry, biochemistry, catalysis, amorphous and liquid systems, synchrotron radiation, and surface phenomena. Contributors explain the underlying theory, how to set up X–ray absorption experiments, and how to analyze the details of the resulting spectra. X-R...

  4. Quantitative investigation of two metallohydrolases by X-ray absorption spectroscopy near-edge spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, W. [Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027 (China); Chu, W.S.; Yang, F.F.; Yu, M.J.; Chen, D.L.; Guo, X.Y. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Zhou, D.W.; Shi, N. [Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027 (China); Marcelli, A. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, P.O. Box 13, Frascati 00044 (Italy); Niu, L.W.; Teng, M.K. [Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui 230027 (China); Gong, W.M. [Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101 (China); Benfatto, M. [Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, P.O. Box 13, Frascati 00044 (Italy); Wu, Z.Y. [Institute of High Energy Physics, Chinese Academy of Sciences, Beijing 100049 (China); Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, P.O. Box 13, Frascati 00044 (Italy)], E-mail: wuzy@ihep.ac.cn

    2007-09-21

    The last several years have witnessed a tremendous increase in biological applications using X-ray absorption spectroscopy (BioXAS), thanks to continuous advancements in synchrotron radiation (SR) sources and detector technology. However, XAS applications in many biological systems have been limited by the intrinsic limitations of the Extended X-ray Absorption Fine Structure (EXAFS) technique e.g., the lack of sensitivity to bond angles. As a consequence, the application of the X-ray absorption near-edge structure (XANES) spectroscopy changed this scenario that is now continuously changing with the introduction of the first quantitative XANES packages such as Minut XANES (MXAN). Here we present and discuss the XANES code MXAN, a novel XANES-fitting package that allows a quantitative analysis of experimental data applied to Zn K-edge spectra of two metalloproteins: Leptospira interrogans Peptide deformylase (LiPDF) and acutolysin-C, a representative of snake venom metalloproteinases (SVMPs) from Agkistrodon acutus venom. The analysis on these two metallohydrolases reveals that proteolytic activities are correlated to subtle conformation changes around the zinc ion. In particular, this quantitative study clarifies the occurrence of the LiPDF catalytic mechanism via a two-water-molecules model, whereas in the acutolysin-C we have observed a different proteolytic activity correlated to structural changes around the zinc ion induced by pH variations.

  5. Quantitative investigation of two metallohydrolases by X-ray absorption spectroscopy near-edge spectroscopy

    International Nuclear Information System (INIS)

    Zhao, W.; Chu, W.S.; Yang, F.F.; Yu, M.J.; Chen, D.L.; Guo, X.Y.; Zhou, D.W.; Shi, N.; Marcelli, A.; Niu, L.W.; Teng, M.K.; Gong, W.M.; Benfatto, M.; Wu, Z.Y.

    2007-01-01

    The last several years have witnessed a tremendous increase in biological applications using X-ray absorption spectroscopy (BioXAS), thanks to continuous advancements in synchrotron radiation (SR) sources and detector technology. However, XAS applications in many biological systems have been limited by the intrinsic limitations of the Extended X-ray Absorption Fine Structure (EXAFS) technique e.g., the lack of sensitivity to bond angles. As a consequence, the application of the X-ray absorption near-edge structure (XANES) spectroscopy changed this scenario that is now continuously changing with the introduction of the first quantitative XANES packages such as Minut XANES (MXAN). Here we present and discuss the XANES code MXAN, a novel XANES-fitting package that allows a quantitative analysis of experimental data applied to Zn K-edge spectra of two metalloproteins: Leptospira interrogans Peptide deformylase (LiPDF) and acutolysin-C, a representative of snake venom metalloproteinases (SVMPs) from Agkistrodon acutus venom. The analysis on these two metallohydrolases reveals that proteolytic activities are correlated to subtle conformation changes around the zinc ion. In particular, this quantitative study clarifies the occurrence of the LiPDF catalytic mechanism via a two-water-molecules model, whereas in the acutolysin-C we have observed a different proteolytic activity correlated to structural changes around the zinc ion induced by pH variations

  6. Femtosecond X-ray magnetic circular dichroism absorption spectroscopy at an X-ray free electron laser

    Energy Technology Data Exchange (ETDEWEB)

    Higley, Daniel J., E-mail: dhigley@stanford.edu; Yuan, Edwin [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Hirsch, Konstantin; Dakovski, Georgi L.; Jal, Emmanuelle; Lutman, Alberto A.; Coslovich, Giacomo; Hart, Philip; Hoffmann, Matthias C.; Mitra, Ankush; Moeller, Stefan; Ohldag, Hendrik; Seaberg, Matthew; Stöhr, Joachim; Nuhn, Heinz-Dieter; Reid, Alex H.; Dürr, Hermann A.; Schlotter, William F. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Liu, Tianmin; MacArthur, James P. [SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); and others

    2016-03-15

    X-ray magnetic circular dichroism spectroscopy using an X-ray free electron laser is demonstrated with spectra over the Fe L{sub 3,2}-edges. The high brightness of the X-ray free electron laser combined with high accuracy detection of incident and transmitted X-rays enables ultrafast X-ray magnetic circular dichroism studies of unprecedented sensitivity. This new capability is applied to a study of all-optical magnetic switching dynamics of Fe and Gd magnetic sublattices in a GdFeCo thin film above its magnetization compensation temperature.

  7. X-ray absorption spectroscopy of U (VI) sorbed onto alumina

    International Nuclear Information System (INIS)

    Kumar, Sumit; Jain, Aishwarya; Tomar, B.S.; Manchanda, V.K.; Poswal, A.K.; Jha, S.N.; Sabharwal, S.C.

    2009-01-01

    Sorption of U (VI) by alumina varying pH has been studied by X-ray absorption Spectroscopy. The experiments were carried out using the EXAFS beamline (BL-8) of INDUS-2 at Raja Ramanna Centre for Advanced Technology, Indore. The absorption intensity was found to increase with the increasing pH of the suspension. (author)

  8. X-ray absorption spectroscopy of CuO.sub.2./sub. chains

    Czech Academy of Sciences Publication Activity Database

    Drechsler, S.L.; Hu, Z.; Málek, Jiří; Rosner, H.; Neudert, R.; Knupfer, M.; Golden, M. S.; Fink, J.

    2003-01-01

    Roč. 131, 3/4 (2003), s. 369-373 ISSN 0022-2291 Institutional research plan: CEZ:AV0Z1010914 Keywords : X-ray absorption spectroscopy * exact diagonalization techniques Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.171, year: 2003

  9. A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions

    International Nuclear Information System (INIS)

    Brown, Matthew A.; Redondo, Amaia Beloqui; Duyckaerts, Nicolas; Mächler, Jean-Pierre; Jordan, Inga; Wörner, Hans Jakob; Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Birrer, Mario; Honegger, Juri; Wetter, Reto; Bokhoven, Jeroen A. van

    2013-01-01

    A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the first liquid microjet endstation capable of operating in vacuum and in ambient pressures up to the equilibrium vapor pressure of liquid water at room temperature. In addition, the Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solutions and buried interfaces from liquid microjet samples. The endstation is designed to operate at the soft X-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K ultraviolet helium lamp for dedicated UPS measurements at the vapor-liquid interface using either He I or He II α lines. The design concept, first results from UPS, soft X-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented

  10. A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions.

    Science.gov (United States)

    Brown, Matthew A; Redondo, Amaia Beloqui; Jordan, Inga; Duyckaerts, Nicolas; Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Müächler, Jean-Pierre; Birrer, Mario; Honegger, Juri; Wetter, Reto; Wörner, Hans Jakob; van Bokhoven, Jeroen A

    2013-07-01

    A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the first liquid microjet endstation capable of operating in vacuum and in ambient pressures up to the equilibrium vapor pressure of liquid water at room temperature. In addition, the Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solutions and buried interfaces from liquid microjet samples. The endstation is designed to operate at the soft X-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K ultraviolet helium lamp for dedicated UPS measurements at the vapor-liquid interface using either He I or He II α lines. The design concept, first results from UPS, soft X-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented.

  11. A new endstation at the Swiss Light Source for ultraviolet photoelectron spectroscopy, X-ray photoelectron spectroscopy, and X-ray absorption spectroscopy measurements of liquid solutions

    Energy Technology Data Exchange (ETDEWEB)

    Brown, Matthew A.; Redondo, Amaia Beloqui; Duyckaerts, Nicolas; Mächler, Jean-Pierre [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland); Jordan, Inga; Wörner, Hans Jakob [Laboratory of Physical Chemistry, ETH Zürich, CH-8093 Zürich (Switzerland); Lee, Ming-Tao; Ammann, Markus; Nolting, Frithjof; Kleibert, Armin; Huthwelker, Thomas; Birrer, Mario; Honegger, Juri; Wetter, Reto [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Bokhoven, Jeroen A. van [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland); Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

    2013-07-15

    A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the first liquid microjet endstation capable of operating in vacuum and in ambient pressures up to the equilibrium vapor pressure of liquid water at room temperature. In addition, the Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solutions and buried interfaces from liquid microjet samples. The endstation is designed to operate at the soft X-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K ultraviolet helium lamp for dedicated UPS measurements at the vapor-liquid interface using either He I or He II α lines. The design concept, first results from UPS, soft X-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented.

  12. I20; the Versatile X-ray Absorption spectroscopy beamline at Diamond Light Source

    International Nuclear Information System (INIS)

    Diaz-Moreno, S; Hayama, S; Amboage, M; Freeman, A; Sutter, J; Duller, G

    2009-01-01

    The Versatile Spectroscopy beamline at Diamond Light Source, I20, is currently under construction and aims to begin operation in late 2009 and early 2010. The beamline aims to cover applications from physics, chemistry and biology through materials, environmental and geological science. Three very distinctive modes of operation will be offered at the beamline: scanning X-ray Absorption spectroscopy (XAS), XAS in dispersive mode, and X-ray emission spectroscopy (XES). To achieve this, the beamline has been designed around two independent experimental end-stations operating from a pair of canted wigglers located in a 5m diamond straight section. One branch of the beamline will deliver monochromatic x-ray radiation of high spectral purity to one of the experimental hutches, whilst the other branch will constitute an energy dispersive spectrometer. The novel design of the beamline allows both branches to operate simultaneously.

  13. X-ray photoemission spectroscopy (XPS) and extended x-ray absorption fine structure (EXAFS) studies of silicate based glasses

    International Nuclear Information System (INIS)

    Karim, D.; Lam, D.J.

    1979-01-01

    The application of the x-ray photoemission spectroscopy (XPS) technique to study the electronic structure and bonding of heavy metal oxides in alkali- and alkali-earth-silicate glasses had been demonstrated. The bonding characteristics of the iron oxide and uranium oxide in sodium silicate glasses were deduced from the changes in the oxygen 1s levels and the heavy metal core levels. It is reasonable to expect that the effect of leaching on the heavy metal ions can be monitored using the appropriate core levels of these ions. To study the effect of leaching on the glass forming network, the valence band structure of the bridging and nonbridging oxygens in sodium silicate glasses were investigated. The measurement of extended x-ray absorption fine-structure (EXAFS) is a relatively new analytical technique for obtaining short range (<5 A) structural information around atoms of a selected species in both solid and fluid systems. Experiments have recently begun to establish the feasibility of using EXAFS to study the bonding of actinides in silicate glasses. Because of the ability of EXAFS to yield specific structural data even in complex multicomponent systems, it could prove to be an invaluable tool in understanding glass structure

  14. Microscale X-ray Absorption Spectroscopy on the GSECARS Sector 13 at the APS

    CERN Document Server

    Stephen-Sutto

    2000-01-01

    GeoSoilEnviroCARS (GSECARS) is a national user facility for frontier research in the earth sciences using synchrotrons radiation at the Advanced Photon Source, Argonne National Laboratory. GSECARS provides earth scientists with access to the high-brilliance hard x-rays from this third-generation synchrotrons light source. The research conducted at this facility will advance our knowledge of the composition, structure and properties of earth materials, the processes they control and the processes that produce them. All principal synchrotron-based analytical techniques in demand by earth scientists are being brought to bear on earth science problems: (1) high-pressure/high-temperature crystallography and spectroscopy using the diamond anvil cell; (2) high-pressure/high-temperature crystallography using the large-volume press; (3) powder, single crystal and interface diffraction; (4) x-ray absorption fine structure (XAFS) spectroscopy; (5) x-ray fluorescence microprobe analysis and microspectroscopy; and (6) mic...

  15. Molecular environment of iodine in naturally iodinated humic substances: Insight from X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Schlegel, Michel L.; Mercier-Bion, Florence; Barre, Nicole; Reiller, Pascal; Moulin, Valerie

    2006-01-01

    The molecular environment of iodine in reference inorganic and organic compounds, and in dry humic and fulvic acids (HAs and FAs) extracted from subsurface and deep aquifers was probed by iodine L-3-edge X-ray absorption spectroscopy. The X-ray absorption near-edge structure (XANES) of iodine spectra from HAs and FAs resembled those of organic references and displayed structural features consistent with iodine forming covalent bonds with organic molecules. Simulation of XANES spectra by linear combination of reference spectra suggested the predominance of iodine forming covalent bonds to aromatic rings (aromatic-bound iodine). Comparison of extended X-ray absorption fine structure (EXAFS) spectra of reference and samples further showed that iodine was surrounded by carbon shells at distances comparable to those for references containing aromatic-bound iodine. Quantitative analysis of EXAFS spectra indicated that iodine was bound to about one carbon at a distance d(I-C) of 2.01(4)-2.04(9) angstrom, which was comparable to the distances observed for aromatic-bound iodine in references (1.99(1)-2.07(6) angstrom), and significantly shorter than that observed for aliphatic-bound iodine (2.15(2)-2.16(2) angstrom). These results are in agreement with previous conclusions from X-ray photoelectron spectroscopy and from electro-spray ionization mass spectrometry. These results collectively suggest that the aromatic-bound iodine is stable in the various aquifers of this study. (authors)

  16. A reaction cell for ambient pressure soft x-ray absorption spectroscopy

    Science.gov (United States)

    Castán-Guerrero, C.; Krizmancic, D.; Bonanni, V.; Edla, R.; Deluisa, A.; Salvador, F.; Rossi, G.; Panaccione, G.; Torelli, P.

    2018-05-01

    We present a new experimental setup for performing X-ray Absorption Spectroscopy (XAS) in the soft X-ray range at ambient pressure. The ambient pressure XAS setup is fully compatible with the ultra high vacuum environment of a synchrotron radiation spectroscopy beamline end station by means of ultrathin Si3N4 membranes acting as windows for the X-ray beam and seal of the atmospheric sample environment. The XAS detection is performed in total electron yield (TEY) mode by probing the drain current from the sample with a picoammeter. The high signal/noise ratio achievable in the TEY mode, combined with a continuous scanning of the X-ray energies, makes it possible recording XAS spectra in a few seconds. The first results show the performance of this setup to record fast XAS spectra from sample surfaces exposed at atmospheric pressure, even in the case of highly insulating samples. The use of a permanent magnet inside the reaction cell enables the measurement of X-ray magnetic circular dichroism at ambient pressure.

  17. Catalysts at work: From integral to spatially resolved X-ray absorption spectroscopy

    DEFF Research Database (Denmark)

    Grunwaldt, Jan-Dierk; Kimmerle, B.; Baiker, A.

    2009-01-01

    available techniques, X-ray absorption spectroscopy (XAS) is a well-suited tool for this purpose as the different selected examples highlight. Two different techniques, scanning and full-field X-ray microscopy/tomography, are described and compared. At first, the tomographic structure of impregnated alumina...... pellets is presented using full-field transmission microtomography and compared to the results obtained with a scanning X-ray microbeam technique to analyse the catalyst bed inside a catalytic quartz glass reactor. On the other hand, by using XAS in scanning microtomography, the structure...... metal-based catalysts. In order to obtain spectroscopic information on the spatial variation of the oxidation state of the catalyst inside the reactor XAS spectra were recorded by scanning with a micro-focussed beam along the catalyst bed. Alternatively, full-field transmission imaging was used...

  18. Redox Chemisty of Tantalum Clusters on Silica Characterized by X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Nemana,S.; Gates, B.

    2006-01-01

    SiO{sub 2}-supported clusters of tantalum were synthesized from adsorbed Ta(CH{sub 2}Ph){sub 5} by treatment in H{sub 2} at 523 K. The surface species were characterized by X-ray absorption spectroscopy (extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray absorption near edge spectroscopy (XANES)) and ultraviolet-visible spectroscopy. The EXAFS data show that SiOO{sub 2}-supported tantalum clusters were characterized by a Ta-Ta coordination number of approximately 2, consistent with the presence of tritantalum clusters, on average. When these were reduced in H{sub 2} and reoxidized in O{sub 2}, the cluster nuclearity remained essentially unchanged, although reduction and oxidation occurred, respectively, as shown by XANES and UV-vis spectra; in the reoxidation, the tantalum oxidation state change was approximately two electronic charges per tritantalum cluster. The data demonstrate an analogy between the chemistry of group 5 metals on the SiO{sub 2} support and their chemistry in solution, as determined by the group of Cotton.

  19. Experimental setup for x-ray absorption spectroscopy at the DESY

    International Nuclear Information System (INIS)

    Rabe, P.; Tolkiehn, G.; Werner, A.

    1979-10-01

    In this paper we describe an apparatus used at the Deutsches Elektronen-Synchrotron (DESY) for the measurement of x-ray absorption spectra, specially designed for the investigation of the extended x-ray absorption fine structure (EXAFS). Performance of the setup is discussed and compared with an apparatus using the bremsstrahlung of a conventional x-ray source. (orig.)

  20. Atomic structure of machined semiconducting chips: An x-ray absorption spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Paesler, M.; Sayers, D.

    1988-12-01

    X-ray absorption spectroscopy (XAS) has been used to examine the atomic structure of chips of germanium that were produced by single point diamond machining. It is demonstrated that although the local (nearest neighbor) atomic structure is experimentally quite similar to that of single crystal specimens information from more distant atoms indicates the presence of considerable stress. An outline of the technique is given and the strength of XAS in studying the machining process is demonstrated.

  1. Note: Application of a pixel-array area detector to simultaneous single crystal x-ray diffraction and x-ray absorption spectroscopy measurements

    International Nuclear Information System (INIS)

    Sun, Cheng-Jun; Brewe, Dale L.; Heald, Steve M.; Zhang, Bangmin; Chen, Jing-Sheng; Chow, G. M.; Venkatesan, T.

    2014-01-01

    X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) are two main x-ray techniques in synchrotron radiation facilities. In this Note, we present an experimental setup capable of performing simultaneous XRD and XAS measurements by the application of a pixel-array area detector. For XRD, the momentum transfer in specular diffraction was measured by scanning the X-ray energy with fixed incoming and outgoing x-ray angles. By selecting a small fixed region of the detector to collect the XRD signal, the rest of the area was available for collecting the x-ray fluorescence for XAS measurements. The simultaneous measurement of XRD and X-ray absorption near edge structure for Pr 0.67 Sr 0.33 MnO 3 film was demonstrated as a proof of principle for future time-resolved pump-probe measurements. A static sample makes it easy to maintain an accurate overlap of the X-ray spot and laser pump beam

  2. Identifying anthropogenic uranium compounds using soft X-ray near-edge absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ward, Jesse D.; Bowden, Mark; Tom Resch, C.; Eiden, Gregory C.; Pemmaraju, C. D.; Prendergast, David; Duffin, Andrew M.

    2017-01-01

    Uranium ores mined for industrial use are typically acid-leached to produce yellowcake and then converted into uranium halides for enrichment and purification. These anthropogenic chemical forms of uranium are distinct from their mineral counterparts. The purpose of this study is to use soft X-ray absorption spectroscopy to characterize several common anthropogenic uranium compounds important to the nuclear fuel cycle. Non-destructive chemical analyses of these compounds is important for process and environmental monitoring and X-ray absorption techniques have several advantages in this regard, including element-specificity, chemical sensitivity, and high spectral resolution. Oxygen K-edge spectra were collected for uranyl nitrate, uranyl fluoride, and uranyl chloride, and fluorine K-edge spectra were collected for uranyl fluoride and uranium tetrafluoride. Interpretation of the data is aided by comparisons to calculated spectra. These compounds have unique spectral signatures that can be used to identify unknown samples.

  3. Investigation of periodically driven systems by x-ray absorption spectroscopy using asynchronous data collection mode

    Science.gov (United States)

    Singh, H.; Donetsky, D.; Liu, J.; Attenkofer, K.; Cheng, B.; Trelewicz, J. R.; Lubomirsky, I.; Stavitski, E.; Frenkel, A. I.

    2018-04-01

    We report the development, testing, and demonstration of a setup for modulation excitation spectroscopy experiments at the Inner Shell Spectroscopy beamline of National Synchrotron Light Source - II. A computer algorithm and dedicated software were developed for asynchronous data processing and analysis. We demonstrate the reconstruction of X-ray absorption spectra for different time points within the modulation pulse using a model system. This setup and the software are intended for a broad range of functional materials which exhibit structural and/or electronic responses to the external stimulation, such as catalysts, energy and battery materials, and electromechanical devices.

  4. Diagnosis of laser ablated carbon particles measured by time-resolved X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Miyashita, Atsumi; Yoda, Osamu; Ohyanagi, T.; Murakami, K.

    1995-01-01

    The time and space resolved properties of laser ablated carbon particles were measured by X-ray absorption spectroscopy using LPX as an X-ray source. The energy density of the irradiation laser on the sample was in the range of 0.5-20J/cm 2 and the time delay was varied between 0 and 120ns. The absorption spectra exhibited several peaks originated from level to level transitions and an intense broad absorption in the energy range of C-K edge. At a delay time of 120ns, the absorption peak from 1s→2p transition of neutral carbon atom (C 0 ), C - , C + and C 2+ ions were observed. The absorption peak from C 0 was stronger as the probing position was closer to the sample surface and decreased rapidly with distance from the sample surface. The absorption peak C 2+ ion was observed only at comparatively distant positions from surface. The maximum speeds of highly charged ions were faster than that of neutral atoms and negative charged ions. The neutral atom and lower charged ions were emitted from the sample even after laser irradiation. The spatial distributions of the laser ablated carbon particles in the localized helium gas environment were measured. In the helium gas environment, the ablation plume was depressed by the helium cloud generated on the top of ablation plume. (author)

  5. An X-ray absorption spectroscopy study of the interactions of Ni2+ with yeast enolase.

    Science.gov (United States)

    Wang, S; Scott, R A; Lebioda, L; Zhou, Z H; Brewer, J M

    1995-05-15

    An x-ray absorption spectroscopy (XAS) study was carried out at pH 7.6 on solutions of Ni2+ and yeast enolase depleted of its physiological cofactor (Mg2+) in the presence or absence of substrate/product, the very strongly bound competitive inhibitor 2-phosphonoacetohydroxamate and Mg2+. Both "conformational" and "catalytic" Ni2+ are distorted octahedral in coordination, in agreement with several spectroscopic studies but in contrast to the coordination in the crystal at pH 6.0. The data are consistent with direct coordination of what must be the catalytic Ni2+ to the phosphate of the substrate, in agreement with some previous data but in disagreement with recent interpretations by other workers. The ligands around the metal ions obtained from the x-ray structure give simulated XAS spectra in good agreement with the observed spectra.

  6. Instrument for x-ray absorption spectroscopy with in situ electrical control characterizations

    International Nuclear Information System (INIS)

    Huang, Chun-Chao; Chang, Shu-Jui; Yang, Chao-Yao; Tseng, Yuan-Chieh; Chou, Hsiung

    2013-01-01

    We report a synchrotron-based setup capable of performing x-ray absorption spectroscopy and x-ray magnetic circular dichroism with simultaneous electrical control characterizations. The setup can enable research concerning electrical transport, element- and orbital-selective magnetization with an in situ fashion. It is a unique approach to the real-time change of spin-polarized electronic state of a material/device exhibiting magneto-electric responses. The performance of the setup was tested by probing the spin-polarized states of cobalt and oxygen of Zn 1-x Co x O dilute magnetic semiconductor under applied voltages, both at low (∼20 K) and room temperatures, and signal variations upon the change of applied voltage were clearly detected

  7. UV-Visible Absorption Spectroscopy Enhanced X-ray Crystallography at Synchrotron and X-ray Free Electron Laser Sources.

    Science.gov (United States)

    Cohen, Aina E; Doukov, Tzanko; Soltis, Michael S

    2016-01-01

    This review describes the use of single crystal UV-Visible Absorption micro-Spectrophotometry (UV-Vis AS) to enhance the design and execution of X-ray crystallography experiments for structural investigations of reaction intermediates of redox active and photosensitive proteins. Considerations for UV-Vis AS measurements at the synchrotron and associated instrumentation are described. UV-Vis AS is useful to verify the intermediate state of an enzyme and to monitor the progression of reactions within crystals. Radiation induced redox changes within protein crystals may be monitored to devise effective diffraction data collection strategies. An overview of the specific effects of radiation damage on macromolecular crystals is presented along with data collection strategies that minimize these effects by combining data from multiple crystals used at the synchrotron and with the X-ray free electron laser.

  8. Hydrothermal Diamond Anvil Cell (HDAC): From Visual Observation to X-ray Absorption Spectroscopy

    Science.gov (United States)

    Bassett, W. A.; Mibe, K.

    2006-05-01

    A fluid sample contained in a Re gasket between two diamond anvils can be subjected to pressures up to 2.5 GPa and temperatures up to 1200°C in a resistively heated hydrothermal diamond anvil cell (HDAC). Thermocouples are used to measure temperature. The constant-volume sample chamber permits isochoric measurements that can be used to determine pressure from the equation of state of H2O and to map phases and properties in P-T space. A movie of reactions between K-feldspar and water up to 2.5 GPa and 880°C illustrates the use of visual observations for mapping coexisting solution, melt, and solid phases. X-ray absorption spectroscopy of ZnBr2 in solution up to 500°C and 500 MPa shows hydrogen bond breaking in the hydration shells of the ZnBr42- and Br- ions with increasing temperature. In other studies the stability field of ikaite (CaCO3·6H2O) has been mapped by visual observation and Raman spectroscopy; the phases of montmorillonite have been mapped by X-ray diffraction; and the leaching of Pb from zircon has been measured by X-ray microprobe.

  9. An x-ray absorption spectroscopy study of Cd binding onto a halophilic archaeon

    International Nuclear Information System (INIS)

    Showalter, Allison R; Bunker, Bruce A; Szymanowski, Jennifer E S; Fein, Jeremy B

    2016-01-01

    X-ray absorption spectroscopy (XAS) and cadmium (Cd) isotherm experiments determine how Cd adsorbs to the surface of halophilic archaeon Halobacterium noricense . This archaeon, isolated from the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico could be involved with the transport of toxic metals stored in the transuranic waste in the salt mine. The isotherm experiments show that adsorption is relatively constant across the tolerable pH range for H. noricense . The XAS results indicate that Cd adsorption occurs predominately via a sulfur site, most likely sulfhydryl, with the same site dominating all measured pH values. (paper)

  10. An x-ray absorption spectroscopy study of Cd binding onto a halophilic archaeon

    Science.gov (United States)

    Showalter, Allison R.; Szymanowski, Jennifer E. S.; Fein, Jeremy B.; Bunker, Bruce A.

    2016-05-01

    X-ray absorption spectroscopy (XAS) and cadmium (Cd) isotherm experiments determine how Cd adsorbs to the surface of halophilic archaeon Halobacterium noricense. This archaeon, isolated from the Waste Isolation Pilot Plant (WIPP) near Carlsbad, New Mexico could be involved with the transport of toxic metals stored in the transuranic waste in the salt mine. The isotherm experiments show that adsorption is relatively constant across the tolerable pH range for H. noricense. The XAS results indicate that Cd adsorption occurs predominately via a sulfur site, most likely sulfhydryl, with the same site dominating all measured pH values.

  11. Strontium Localization in Bone Tissue Studied by X-Ray Absorption Spectroscopy

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Raffalt, Anders Christer; Ståhl, Kenny

    2014-01-01

    Strontium has recently been introduced as a pharmacological agent for the treatment and prevention of osteoporosis. We determined the localization of strontium incorporated into bone matrix from dogs treated with Sr malonate by X-ray absorption spectroscopy. A new approach for analyzing the X...... highly ordered sites, and at least 30 % is located at less ordered sites where only the first solvation shell is resolved, suggesting that strontium is sur- rounded by only oxygen atoms similar to Sr2? in solution. Strontium was furthermore shown to be absorbed in collagen in which it obtains a higher...

  12. X-ray absorption spectroscopy in the keV range with laser generated high harmonic radiation

    International Nuclear Information System (INIS)

    Seres, Enikoe; Seres, Jozsef; Spielmann, Christian

    2006-01-01

    By irradiating He and Ne atoms with 3 mJ, 12 fs, near infrared laser pulses from a tabletop laser system, the authors generated spatially and temporally coherent x rays up to a photon energy of 3.5 keV. With this source it is possible to use high-harmonic radiation for x-ray absorption spectroscopy in the keV range. They were able to clearly resolve the L absorption edges of titanium and copper and the K edges of aluminum and silicon. From the fine structure of the x-ray absorption they estimated the interatomic distances

  13. A new flexible monochromator setup for quick scanning x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stoetzel, J.; Luetzenkirchen-Hecht, D.; Frahm, R. [Fachbereich C, Physik, Bergische Universitaet Wuppertal, Gaussstr. 20, 42097 Wuppertal (Germany)

    2010-07-15

    A new monochromator setup for quick scanning x-ray absorption spectroscopy in the subsecond time regime is presented. Novel driving mechanics allow changing the energy range of the acquired spectra by remote control during data acquisition for the first time, thus dramatically increasing the flexibility and convenience of this method. Completely new experiments are feasible due to the fact that time resolution, edge energy, and energy range of the acquired spectra can be changed continuously within seconds without breaking the vacuum of the monochromator vessel and even without interrupting the measurements. The advanced mechanics are explained in detail and the performance is characterized with x-ray absorption spectra of pure metal foils. The energy scale was determined by a fast and accurate angular encoder system measuring the Bragg angle of the monochromator crystal with subarcsecond resolution. The Bragg angle range covered by the oscillating crystal can currently be changed from 0 deg. to 3.0 deg. within 20 s, while the mechanics are capable to move with frequencies of up to ca. 35 Hz, leading to ca. 14 ms/spectrum time resolution. A new software package allows performing programmed scan sequences, which enable the user to measure stepwise with alternating parameters in predefined time segments. Thus, e.g., switching between edges scanned with the same energy range is possible within one in situ experiment, while also the time resolution can be varied simultaneously. This progress makes the new system extremely user friendly and efficient to use for time resolved x-ray absorption spectroscopy at synchrotron radiation beamlines.

  14. X-ray Absorption Spectroscopy Unveils the Formation of Gold Nanoparticles in Corn X-ray Absorption Spectroscopy Unveils the Formation of Gold Nanoparticles in Corn

    Directory of Open Access Journals (Sweden)

    Gustavo Cruz-Jiménez

    2012-02-01

    Full Text Available En este estudio se determinó, mediante espectroscopía de absorción de rayos-X, la posible biotransformación de oro en maíz (variedad Golden que se germinó y creció en KAuCl4. Adicionalmente se investigó el efecto de la tiourea y el tiocianato de amonio en la absorción de oro por la planta de maíz. Los resultados indicaron que concentraciones menores a 160 mg Au/L, no afectaron la germinación o el crecimiento de las plántulas. Tanto la tiourea como el tiocianato de amonio incrementaron 6 veces el contenido de oro en las raíces, mientras que la tiourea provocó un incremento de 10 veces la concentración de oro en tallos con respecto a los tratamientos sin este compuesto. El 91% del oro en el maíz se encontró como Au(0 y el resto como Au(III. Los análisis de estructura fi na revelaron que el oro se encontraba con un número de coordinación de 9,5 aproximadamente a 2,86 Å, indicando una esfera de coordinación incompleta, lo cual implica la presencia de una nano-fase. Usando la ecuación de Borowski se determinó que las nanopartículas tenían un tamaño promedio de 10,36 nm.In this study, X-ray absorption spectroscopy was used to determine the possible gold biotransformation by Zea mays (corn var. Golden, germinated and grown in a medium spikedwith KAuCl4. In addition, the gold uptake capacity of corn assisted by thiourea and ammoniumthiocyanate was investigated. Results showed that up to 160 mg/L, gold did no treduce corn seed germination or plant growth. Both thiourea and ammonium thiocyanateresulted in a 6-fold increase of gold concentration in roots and thiourea promoted a 10-fold increase of gold concentration in shoots. X-ray absorption near edge structure studies demonstrated that approximately 91% of the gold present in plant samples was Au(0. Theremaining 9% was present as Au(III. In addition, extended X-ray absorption fi ne structureresults showed that in corn roots, the gold coordination number was around 9

  15. Characterization of metallic nanoparticles by high-resolution X-ray absorption and X-ray emission spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kuehn, Timna-Josua

    2012-03-15

    In almost all areas of technology, metallic nanoparticles are of interest due to their special thermal, electronic, magnetic and optical properties. Their special properties are mainly due to their small size which implies the relevance of quantum effects as well as the significance of the surface: For 2 nm nanoparticles, the surface-to-volume ratio is already 1:1. However, the identification of surface-to-volume interactions - that are responsible for the new properties - is a difficult task due to the small size that inhibits a lot of 'standard' techniques to be applicable. Here X-ray absorption/emission spectroscopy (XAS/XES) is a favorable tool for the characterization of nanoparticles, independent on size, degree of crystallinity and shape/condition of the surface. Using XAS, a tempered nanosized Co{sub 3}Pt/C catalyst have been investigated. Its outstanding oxygen-reduction reaction (ORR) properties in a fuel cell could be related to a lowered Pt 5d-band center connected to a tightened Pt-Pt bonding distance, leading to a weakening of the oxygen adsorption strength so that the ORR may proceed faster. One drawback remains, however, as the properties found by (standard) XAS are summed up for different chemical environments of the chosen element. Thus, no distinction can be made between, e.g., the pure metal in a nanoparticles' interior and the ligated metal in the outer shells or surface. Here, high-resolution fluorescence-detected XAS (HRFD-XAS) provides additional opportunities as, due to its chemical sensitivity, it leads to site-selective XAS. For a system of 6 nm sized Co nanoparticles, build up of a metallic core surrounded by a protecting shell, that resulted from the 'smooth oxidation' process, this technique of site-selective XAS was proven to be applicable. For the first time, the interior and outer shell of a metallic nanoparticle could be characterized separately. In particular, the Co-hcp phase could be determined for the

  16. Annealing induced atomic rearrangements on (Ga,In) (N,As) probed by hard X-ray photoelectron spectroscopy and X-ray absorption fine structure.

    Science.gov (United States)

    Ishikawa, Fumitaro; Higashi, Kotaro; Fuyuno, Satoshi; Morifuji, Masato; Kondow, Masahiko; Trampert, Achim

    2018-04-13

    We study the effects of annealing on (Ga 0.64 ,In 0.36 ) (N 0.045 ,As 0.955 ) using hard X-ray photoelectron spectroscopy and X-ray absorption fine structure measurements. We observed surface oxidation and termination of the N-As bond defects caused by the annealing process. Specifically, we observed a characteristic chemical shift towards lower binding energies in the photoelectron spectra related to In. This phenomenon appears to be caused by the atomic arrangement, which produces increased In-N bond configurations within the matrix, as indicated by the X-ray absorption fine structure measurements. The reduction in the binding energies of group-III In, which occurs concomitantly with the atomic rearrangements of the matrix, causes the differences in the electronic properties of the system before and after annealing.

  17. X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

    Energy Technology Data Exchange (ETDEWEB)

    Vitova, Tonya

    2008-02-15

    The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu{sup 1+} and Cu{sup 2+}) and Fe (Fe{sup 2+} and Fe{sup 3+}) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn{sup 2+} and Mn{sup 3+} in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu{sup 1+}) and sixfold (Cu{sup 2+}) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with {sup 3}He{sup 2+} ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

  18. Probing the CZTS/CdS heterojunction utilizing photoelectrochemistry and x-ray absorption spectroscopy

    Science.gov (United States)

    Turnbull, Matthew J.; Vaccarello, Daniel; Wong, Jonathan; Yiu, Yun Mui; Sham, Tsun-Kong; Ding, Zhifeng

    2018-04-01

    The importance of renewable resources is becoming more and more influential on research due to the depletion of fossil fuels. Cost-effective ways of harvesting solar energy should also be at the forefront of these investigations. Cu2ZnSnS4 (CZTS) solar cells are well within the frame of these goals, and a thorough understanding of how they are made and processed synthetically is crucial. The CZTS/CdS heterojunction was examined using photoelectrochemistry and synchrotron radiation (SR) spectroscopy. These tools provided physical insights into this interface that was formed by the electrophoretic deposition of CZTS nanocrystals and chemical bath deposition (CBD) of CdS for the respective films. It was discovered that CBD induced a change in the local and long range environment of the Zn in the CZTS lattice, which was detrimental to the photoresponse. X-ray absorption near-edge structures and extended X-ray absorption fine structures (EXAFSs) of the junction showed that this change was at an atomic level and was associated with the coordination of oxygen to zinc. This was confirmed through FEFF fitting of the EXAFS and through IR spectroscopy. It was found that this change in both photoresponse and the Zn coordination can be reversed with the use of low temperature annealing. Investigating CZTS through SR techniques provides detailed structural information of minor changes from the zinc perspective.

  19. X-ray absorption spectroscopy investigation of structurally modified lithium niobate crystals

    International Nuclear Information System (INIS)

    Vitova, Tonya

    2008-02-01

    The type and concentration of impurity centers in different valence states are crucial for tuning the photorefractive properties of doped Lithium Niobate (LN) crystals. X-ray Absorption Spectroscopy (XAS) is an appropriate tool for studying the local structure of impurity centers. XAS combined with absorption in UV/VIS/IR and High Resolution X-ray Emission Spectroscopy (HRXES) provide information about the valence state of the dopant ions in as-grown, reduced or oxidized doped LN crystals. Cu (Cu 1+ and Cu 2+ ) and Fe (Fe 2+ and Fe 3+ ) atoms are found in two different valence states, whereas there are indications for a third Mn valency, in addition to Mn 2+ and Mn 3+ in manganese-doped LN crystals. One of the charge compensation mechanisms during reduction of copper- doped LN crystals is outgassing of oxygen atoms. Cu ions in the reduced crystals have at least two different site symmetries: twofold (Cu 1+ ) and sixfold (Cu 2+ ) coordinated by O atoms. Fe and Mn atoms are coordinated by six O atoms. Cu and Fe ions are found to occupy only Li sites, whereas Mn ions are also incorporated into Li and Nb sites. The refractive index change in LN crystals irradiated with 3 He 2+ ions is caused by structurally disordered centers, where Nb atoms are displaced from normal crystallographic sites and Li or/and O vacancies are present. (orig.)

  20. Site- and phase-selective x-ray absorption spectroscopy based on phase-retrieval calculation

    International Nuclear Information System (INIS)

    Kawaguchi, Tomoya; Fukuda, Katsutoshi; Matsubara, Eiichiro

    2017-01-01

    Understanding the chemical state of a particular element with multiple crystallographic sites and/or phases is essential to unlocking the origin of material properties. To this end, resonant x-ray diffraction spectroscopy (RXDS) achieved through a combination of x-ray diffraction (XRD) and x-ray absorption spectroscopy (XAS) techniques can allow for the measurement of diffraction anomalous fine structure (DAFS). This is expected to provide a peerless tool for electronic/local structural analyses of materials with complicated structures thanks to its capability to extract spectroscopic information about a given element at each crystallographic site and/or phase. At present, one of the major challenges for the practical application of RXDS is the rigorous determination of resonant terms from observed DAFS, as this requires somehow determining the phase change in the elastic scattering around the absorption edge from the scattering intensity. This is widely known in the field of XRD as the phase problem. The present review describes the basics of this problem, including the relevant background and theory for DAFS and a guide to a newly-developed phase-retrieval method based on the logarithmic dispersion relation that makes it possible to analyze DAFS without suffering from the intrinsic ambiguities of conventional iterative-fitting. Several matters relating to data collection and correction of RXDS are also covered, with a final emphasis on the great potential of powder-sample-based RXDS (P-RXDS) to be used in various applications relevant to practical materials, including antisite-defect-type electrode materials for lithium-ion batteries. (topical review)

  1. X-ray Absorption Spectroscopy Characterization of Electrochemical Processes in Renewable Energy Storage and Conversion Devices

    Energy Technology Data Exchange (ETDEWEB)

    Farmand, Maryam [George Washington Univ., Washington, DC (United States)

    2013-05-19

    The development of better energy conversion and storage devices, such as fuel cells and batteries, is crucial for reduction of our global carbon footprint and improving the quality of the air we breathe. However, both of these technologies face important challenges. The development of lower cost and better electrode materials, which are more durable and allow more control over the electrochemical reactions occurring at the electrode/electrolyte interface, is perhaps most important for meeting these challenges. Hence, full characterization of the electrochemical processes that occur at the electrodes is vital for intelligent design of more energy efficient electrodes. X-ray absorption spectroscopy (XAS) is a short-range order, element specific technique that can be utilized to probe the processes occurring at operating electrode surfaces, as well for studying the amorphous materials and nano-particles making up the electrodes. It has been increasingly used in recent years to study fuel cell catalysts through application of the and #916; and mgr; XANES technique, in combination with the more traditional X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) techniques. The and #916; and mgr; XANES data analysis technique, previously developed and applied to heterogeneous catalysts and fuel cell electrocatalysts by the GWU group, was extended in this work to provide for the first time space resolved adsorbate coverages on both electrodes of a direct methanol fuel cell. Even more importantly, the and #916; and mgr; technique was applied for the first time to battery relevant materials, where bulk properties such as the oxidation state and local geometry of a cathode are followed.

  2. Characterising legacy spent nuclear fuel pond materials using microfocus X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bower, W.R. [Research Centre for Radwaste Disposal, School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); National Nuclear Laboratory, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE (United Kingdom); Centre for Radiochemistry Research, Chemistry Building, The University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom); Morris, K. [Research Centre for Radwaste Disposal, School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom); Mosselmans, J.F.W. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Thompson, O.R. [National Nuclear Laboratory, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE (United Kingdom); Banford, A.W. [National Nuclear Laboratory, Chadwick House, Warrington Road, Birchwood Park, Warrington, WA3 6AE (United Kingdom); School of Chemical Engineering and Analytical Science, The University of Manchester, Oxford Road, Manchester, M13 9PL (United Kingdom); Law, K. [Centre for Radiochemistry Research, Chemistry Building, The University of Manchester, Brunswick Street, Manchester M13 9PL (United Kingdom); Pattrick, R.A.D., E-mail: richard.pattrick@manchester.ac.uk [Research Centre for Radwaste Disposal, School of Earth and Environmental Sciences, The University of Manchester, Oxford Road, Manchester M13 9PL (United Kingdom)

    2016-11-05

    Highlights: • A sample from a spent fuel pond wall has been analysed via X-ray spectroscopy. • Autoradiography shows a patchy distribution of radioactivity on the core face. • μXAS across a ‘hot spot’ showed Sr associates with the TiO{sub 2} pigment in the paint. • Original concrete coatings prove effective at limiting radionuclide migration. • Sorption studies show Sr immobilisation by the concrete and Cs by aggregate clasts. - Abstract: Analysis of a radioactive, coated concrete core from the decommissioned, spent nuclear fuel cooling pond at the Hunterston-A nuclear site (UK) has provided a unique opportunity to study radionuclides within a real-world system. The core, obtained from a dividing wall and sampled at the fill level of the pond, exhibited radioactivity (dominantly {sup 137}Cs and {sup 90}Sr) heterogeneously distributed across both painted faces. Chemical analysis of the core was undertaken using microfocus spectroscopy at Diamond Light Source, UK. Mapping of Sr across the surface coatings using microfocus X-ray fluorescence (μXRF) combined with X-ray absorption spectroscopy showed that Sr was bound to TiO{sub 2} particles in the paint layers, suggesting an association between TiO{sub 2} and radiostrontium. Stable Sr and Cs sorption experiments using concrete coupons were also undertaken to assess their interactions with the bulk concrete in case of a breach in the coating layers. μXRF and scanning electron microscopy showed that Sr was immobilized by the cement phases, whilst at the elevated experimental concentrations, Cs was associated with clay minerals in the aggregates. This study provides a crucial insight into poorly understood infrastructural contamination in complex systems and is directly applicable to the UK’s nuclear decommissioning efforts.

  3. Simulating systematic errors in X-ray absorption spectroscopy experiments: Sample and beam effects

    Energy Technology Data Exchange (ETDEWEB)

    Curis, Emmanuel [Laboratoire de Biomathematiques, Faculte de Pharmacie, Universite Rene, Descartes (Paris V)-4, Avenue de l' Observatoire, 75006 Paris (France)]. E-mail: emmanuel.curis@univ-paris5.fr; Osan, Janos [KFKI Atomic Energy Research Institute (AEKI)-P.O. Box 49, H-1525 Budapest (Hungary); Falkenberg, Gerald [Hamburger Synchrotronstrahlungslabor (HASYLAB), Deutsches Elektronen-Synchrotron (DESY)-Notkestrasse 85, 22607 Hamburg (Germany); Benazeth, Simone [Laboratoire de Biomathematiques, Faculte de Pharmacie, Universite Rene, Descartes (Paris V)-4, Avenue de l' Observatoire, 75006 Paris (France); Laboratoire d' Utilisation du Rayonnement Electromagnetique (LURE)-Ba-hat timent 209D, Campus d' Orsay, 91406 Orsay (France); Toeroek, Szabina [KFKI Atomic Energy Research Institute (AEKI)-P.O. Box 49, H-1525 Budapest (Hungary)

    2005-07-15

    The article presents an analytical model to simulate experimental imperfections in the realization of an X-ray absorption spectroscopy experiment, performed in transmission or fluorescence mode. Distinction is made between sources of systematic errors on a time-scale basis, to select the more appropriate model for their handling. For short time-scale, statistical models are the most suited. For large time-scale, the model is developed for sample and beam imperfections: mainly sample inhomogeneity, sample self-absorption, beam achromaticity. The ability of this model to reproduce the effects of these imperfections is exemplified, and the model is validated on real samples. Various potential application fields of the model are then presented.

  4. Simulating systematic errors in X-ray absorption spectroscopy experiments: Sample and beam effects

    International Nuclear Information System (INIS)

    Curis, Emmanuel; Osan, Janos; Falkenberg, Gerald; Benazeth, Simone; Toeroek, Szabina

    2005-01-01

    The article presents an analytical model to simulate experimental imperfections in the realization of an X-ray absorption spectroscopy experiment, performed in transmission or fluorescence mode. Distinction is made between sources of systematic errors on a time-scale basis, to select the more appropriate model for their handling. For short time-scale, statistical models are the most suited. For large time-scale, the model is developed for sample and beam imperfections: mainly sample inhomogeneity, sample self-absorption, beam achromaticity. The ability of this model to reproduce the effects of these imperfections is exemplified, and the model is validated on real samples. Various potential application fields of the model are then presented

  5. Time-resolved pump-probe X-ray absorption fine structure spectroscopy of Gaq3

    International Nuclear Information System (INIS)

    Dicke, Benjamin

    2013-01-01

    Gallium(tris-8-hydroxyquinoline) (Gaq 3 ) belongs to a class of metal organic compounds, used as electron transport layer and emissive layer in organic light emitting diodes. Many research activities have concentrated on the optical and electronic properties, especially of the homologue molecule aluminum(tris-8-hydroxyquinoline) (Alq 3 ). Knowledge of the first excited state S 1 structure of these molecules could provide deeper insight into the processes involved into the operation of electronic devices, such as OLEDs and, hence, it could further improve their efficiency and optical properties. Until now the excited state structure could not be determined experimentally. Most of the information about this structure mainly arises from theoretical calculations. X-ray absorption fine structure (XAFS) spectroscopy is a well developed technique to determine both, the electronic and the geometric properties of a sample. The connection of ultrashort pulsed X-ray sources with a pulsed laser system offers the possibility to use XAFS as a tool for studying the transient changes of a sample induced by a laser pulse. In the framework of this thesis a new setup for time-resolved pump-probe X-ray absorption spectroscopy at PETRA III beamline P11 was developed for measuring samples in liquid form. In this setup the sample is pumped into its photo-excited state by a femtosecond laser pump pulse with 343 nm wavelength and after a certain time delay probed by an X-ray probe pulse. In this way the first excited singlet state S 1 of Gaq 3 dissolved in benzyl alcohol was analyzed. A structural model for the excited state structure of the Gaq 3 molecule based on the several times reproduced results of the XAFS experiments is proposed. According to this model it was found that the Ga-N A bond length is elongated, while the Ga-O A bond length is shortened upon photoexcitation. The dynamics of the structural changes were not the focus of this thesis. Nevertheless the excited state lifetime

  6. X-ray absorption spectroscopy and EPR studies of oriented spinach thylakoid preparations

    Energy Technology Data Exchange (ETDEWEB)

    Andrews, J.C. [Univ. of California, Berkeley, CA (United States). Dept. of Chemistry]|[Lawrence Berkeley Lab., CA (United States). Structural Biology Div.

    1995-08-01

    In this study, oriented Photosystem II (PS II) particles from spinach chloroplasts are studied with electron paramagnetic resonance (EPR) and x-ray absorption spectroscopy (XAS) to determine more details of the structure of the oxygen evolving complex (OEC). The nature of halide binding to Mn is also studied with Cl K-edge and Mn EXAFS (extended x-ray absorption fine structure) of Mn-Cl model compounds, and with Mn EXAFS of oriented PS II in which Br has replaced Cl. Attention is focused on the following: photosynthesis and the oxygen evolving complex; determination of mosaic spread in oriented photosystem II particles from signal II EPR measurement; oriented EXAFS--studies of PS II in the S{sub 2} state; structural changes in PS II as a result of treatment with ammonia: EPR and XAS studies; studies of halide binding to Mn: Cl K-edge and Mn EXAFS of Mn-Cl model compounds and Mn EXAFS of oriented Br-treated photosystem II.

  7. Design and conception of an experiment setup for X-Ray absorption spectroscopy on radioactive material

    International Nuclear Information System (INIS)

    Chabane, A.

    1997-01-01

    In the field of the nuclear cycle waste management, the law of december 30, 1991(article 4) gives the frame of the research programs to be conducted. This should lead to o political decision concerning the end of the nuclear fuel cycle. To date, efforts are coordinated by three research groups: PRACTIS, GEDEON and FORPRO. This work, dealing with the development of a radioactive cell for X-ray Absorption Spectroscopy measurements (XAS) is part of PRACTIS goals. It devises into two parts that deal with the conception of the experiment setup (Chapter I) and with the first test that been carried out with X-ray Absorption measurements on radioactive materials (Chapter II), respectively. An introduction on the nuclear fuel cycle and the use of synchrotron radiation for XAS is also given. More precisely, in the first part of this work, we deal with the difficulties that are related to the development of such devises for radioactive samples on a synchrotron beam line. Two constrains have to be taken into account: the technical aspect and the safety aspect. In the second part, we consider the use of grabbing additional structural information on the actinide complexes, both in liquid and solid phases (as amorphous phases for instance). These data on the local order (EXAFS), as well as on the electronic information that can be obtained (XANES) are to be completed with results of the other probing techniques. (author)

  8. Time-resolved x-ray absorption spectroscopy: Watching atoms dance

    Science.gov (United States)

    Milne, Chris J.; Pham, Van-Thai; Gawelda, Wojciech; van der Veen, Renske M.; El Nahhas, Amal; Johnson, Steven L.; Beaud, Paul; Ingold, Gerhard; Lima, Frederico; Vithanage, Dimali A.; Benfatto, Maurizio; Grolimund, Daniel; Borca, Camelia; Kaiser, Maik; Hauser, Andreas; Abela, Rafael; Bressler, Christian; Chergui, Majed

    2009-11-01

    The introduction of pump-probe techniques to the field of x-ray absorption spectroscopy (XAS) has allowed the monitoring of both structural and electronic dynamics of disordered systems in the condensed phase with unprecedented accuracy, both in time and in space. We present results on the electronically excited high-spin state structure of an Fe(II) molecular species, [FeII(bpy)3]2+, in aqueous solution, resolving the Fe-N bond distance elongation as 0.2 Å. In addition an analysis technique using the reduced χ2 goodness of fit between FEFF EXAFS simulations and the experimental transient absorption signal in energy space has been successfully tested as a function of excited state population and chemical shift, demonstrating its applicability in situations where the fractional excited state population cannot be determined through other measurements. Finally by using a novel ultrafast hard x-ray 'slicing' source the question of how the molecule relaxes after optical excitation has been successfully resolved using femtosecond XANES.

  9. Characterising legacy spent nuclear fuel pond materials using microfocus X-ray absorption spectroscopy.

    Science.gov (United States)

    Bower, W R; Morris, K; Mosselmans, J F W; Thompson, O R; Banford, A W; Law, K; Pattrick, R A D

    2016-11-05

    Analysis of a radioactive, coated concrete core from the decommissioned, spent nuclear fuel cooling pond at the Hunterston-A nuclear site (UK) has provided a unique opportunity to study radionuclides within a real-world system. The core, obtained from a dividing wall and sampled at the fill level of the pond, exhibited radioactivity (dominantly (137)Cs and (90)Sr) heterogeneously distributed across both painted faces. Chemical analysis of the core was undertaken using microfocus spectroscopy at Diamond Light Source, UK. Mapping of Sr across the surface coatings using microfocus X-ray fluorescence (μXRF) combined with X-ray absorption spectroscopy showed that Sr was bound to TiO2 particles in the paint layers, suggesting an association between TiO2 and radiostrontium. Stable Sr and Cs sorption experiments using concrete coupons were also undertaken to assess their interactions with the bulk concrete in case of a breach in the coating layers. μXRF and scanning electron microscopy showed that Sr was immobilized by the cement phases, whilst at the elevated experimental concentrations, Cs was associated with clay minerals in the aggregates. This study provides a crucial insight into poorly understood infrastructural contamination in complex systems and is directly applicable to the UK's nuclear decommissioning efforts. Copyright © 2016 The Authors. Published by Elsevier B.V. All rights reserved.

  10. Near-Edge X-ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold

    Energy Technology Data Exchange (ETDEWEB)

    Willey, T M; Fabbri, J; Lee, J I; Schreiner, P; Fokin, A A; Tkachenko, B A; Fokina, N A; Dahl, J; Carlson, B; Vance, A L; Yang, W; Terminello, L J; van Buuren, T; Melosh, N

    2007-11-27

    Diamondoids, hydrocarbon molecules with cubic-diamond-cage structures, have unique properties with potential value for nanotechnology. The availability and ability to selectively functionalize this special class of nanodiamond materials opens new possibilities for surface-modification, for high-efficiency field emitters in molecular electronics, as seed crystals for diamond growth, or as robust mechanical coatings. The properties of self-assembled monolayers (SAMs) of diamondoids are thus of fundamental interest for a variety of emerging applications. This paper presents the effects of thiol substitution position and polymantane order on diamondoid SAMs on gold using near-edge X-ray absorption fine structure spectroscopy (NEXAFS) and X-ray photoelectron spectroscopy (XPS). A framework to determine both molecular tilt and twist through NEXAFS is presented and reveals highly ordered diamondoid SAMs, with the molecular orientation controlled by the thiol location. C 1s and S 2p binding energies are lower in adamantane thiol than alkane thiols on gold by 0.67 {+-} 0.05 eV and 0.16 {+-} 0.04 eV respectively. These binding energies vary with diamondoid monolayer structure and thiol substitution position, consistent with different amounts of steric strain and electronic interaction with the substrate. This work demonstrates control over the assembly, in particular the orientational and electronic structure, providing a flexible design of surface properties with this exciting new class of diamond clusters.

  11. A flexible gas flow reaction cell for in situ x-ray absorption spectroscopy studies

    Energy Technology Data Exchange (ETDEWEB)

    Kroner, Anna B., E-mail: anna.kroner@diamond.ac.uk; Gilbert, Martin; Duller, Graham; Cahill, Leo; Leicester, Peter; Woolliscroft, Richard; Shotton, Elizabeth J. [Diamond Light Source Ltd., Diamond House, Harwell Science and Innovation Campus, Chilton, Oxfordshire, OX110DE (United Kingdom); Mohammed, Khaled M. H. [UK Catalysis Hub, Research Complex at Harwell, Rutherford Appleton Laboratory, Chilton, Oxfordshire, OX110FA (United Kingdom); School of Chemistry, University of Southampton, Southampton, SO17 1BJ (United Kingdom)

    2016-07-27

    A capillary-based sample environment with hot air blower and integrated gas system was developed at Diamond to conduct X-ray absorption spectroscopy (XAS) studies of materials under time-resolved, in situ conditions. The use of a hot air blower, operating in the temperature range of 298-1173 K, allows introduction of other techniques e.g. X-ray diffraction (XRD), Raman spectroscopy for combined techniques studies. The flexibility to use either quartz or Kapton capillaries allows users to perform XAS measurement at energies as low as 5600 eV. To demonstrate performance, time-resolved, in situ XAS results of Rh catalysts during the process of activation (Rh K-edge, Ce L{sub 3}-edge and Cr K-edge) and the study of mixed oxide membrane (La{sub 0.6}Sr{sub 0.4}Co{sub 0.2}Fe{sub 0.8}O{sub 3−δ}) under various partial oxygen pressure conditions are described.

  12. First combined total reflection X-ray fluorescence and grazing incidence X-ray absorption spectroscopy characterization of aeolian dust archived in Antarctica and Alpine deep ice cores

    Energy Technology Data Exchange (ETDEWEB)

    Cibin, G. [Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxon OX110DE (United Kingdom); IMONT/EIM, Ente Italiano della Montagna, P.za dei Caprettari 70, 00176 Roma (Italy); Universita' degli Studi di Roma Tre, Dipartimento di Scienze Geologiche, L.go S. Leonardo Murialdo 1, 00146 Roma (Italy)], E-mail: giannantonio.cibin@diamond.ac.uk; Marcelli, A. [INFN - Laboratori Nazionali di Frascati, P.O. Box 13, 00044 Frascati (Roma) (Italy); Maggi, V. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Sala, M. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Universita degli Studi di Milano, Dipartimento di Scienze della Terra ' A. Desio' , Sez. Mineralogia, Via Mangiagalli 34, 20133 Milano (Italy); Marino, F.; Delmonte, B. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Albani, S. [Universita degli Studi di Milano-Bicocca, Dipartimento di Scienze dell' Ambiente e del Territorio, Piazza della Scienza 1, 20126 Milano (Italy); Universita degli Studi di Siena, Dottorato in Scienze Polari, via Laterina 8, 53100 Siena (Italy); Pignotti, S. [IMONT/EIM, Ente Italiano della Montagna, P.za dei Caprettari 70, 00176 Roma (Italy)

    2008-12-15

    Aeolian mineral dust archived in polar and mid latitude ice cores represents a precious proxy for assessing environmental and climatic variations at different timescales. In this respect, the identification of dust mineralogy plays a key role. In this work we performed the first preliminary X-ray absorption spectroscopy (XAS) experiments on mineral dust particles extracted from Antarctic and from Alpine firn cores using grazing incidence geometry at the Fe K-edge. A dedicated high vacuum experimental chamber was set up for normal-incidence and total-reflection X-Ray Fluorescence and Absorption Spectroscopy analyses on minor amounts of mineral materials at the Stanford Synchrotron Radiation Laboratory. Results show that this experimental technique and protocol allows recognizing iron inclusion mineral fraction on insoluble dust in the 1-10 {mu}g range.

  13. First combined total reflection X-ray fluorescence and grazing incidence X-ray absorption spectroscopy characterization of aeolian dust archived in Antarctica and Alpine deep ice cores

    International Nuclear Information System (INIS)

    Cibin, G.; Marcelli, A.; Maggi, V.; Sala, M.; Marino, F.; Delmonte, B.; Albani, S.; Pignotti, S.

    2008-01-01

    Aeolian mineral dust archived in polar and mid latitude ice cores represents a precious proxy for assessing environmental and climatic variations at different timescales. In this respect, the identification of dust mineralogy plays a key role. In this work we performed the first preliminary X-ray absorption spectroscopy (XAS) experiments on mineral dust particles extracted from Antarctic and from Alpine firn cores using grazing incidence geometry at the Fe K-edge. A dedicated high vacuum experimental chamber was set up for normal-incidence and total-reflection X-Ray Fluorescence and Absorption Spectroscopy analyses on minor amounts of mineral materials at the Stanford Synchrotron Radiation Laboratory. Results show that this experimental technique and protocol allows recognizing iron inclusion mineral fraction on insoluble dust in the 1-10 μg range

  14. A structural study of bone changes in knee osteoarthritis by synchrotron-based X-ray fluorescence and X-ray absorption spectroscopy techniques

    Science.gov (United States)

    Sindhupakorn, Bura; Thienpratharn, Suwittaya; Kidkhunthod, Pinit

    2017-10-01

    Osteoarthritis (OA) is characterized by degeneration of articular cartilage and thickening of subchondral bone. The present study investigated the changing of biochemical components of cartilage and bone compared between normal and OA people. Using Synchrotron-based X-ray fluorescence (SR-XRF) and X-ray absorption spectroscopy (XAS) techniquesincluding X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) were employed for the bone changes in kneeosteoarthritisstudies. The bone samples were collected from various osteoarthritis patients with both male and female in the ages range between 20 and 74 years old. SR-XRF results excited at 4240 eV for Ca elements show a majority three main groups, based on their XRF intensities, 20-36 years, 40-60 years and over 70 years, respectively. By employing XAS techniques, XANES features can be used to clearly explain in term of electronic transitions occurring in bone samples which are affected from osteoarthritis symptoms. Moreover, a structural change around Ca ions in bone samples is obviously obtained by EXAFS results indicating an increase of Ca-amorphous phase when the ages increase.

  15. Correlated single-crystal electronic absorption spectroscopy and X-ray crystallography at NSLS beamline X26-C

    International Nuclear Information System (INIS)

    Orville, A.M.; Buono, R.; Cowan, M.; Heroux, A.; Shea-McCarthy, G.; Schneider, D.K.; Skinner, J.M.; Skinner, M.J.; Stoner-Ma, D.; Sweet, R.M.

    2011-01-01

    The research philosophy and new capabilities installed at NSLS beamline X26-C to support electronic absorption and Raman spectroscopies coupled with X-ray diffraction are reviewed. This beamline is dedicated full time to multidisciplinary studies with goals that include revealing the relationship between the electronic and atomic structures in macromolecules. The beamline instrumentation has been fully integrated such that optical absorption spectra and X-ray diffraction images are interlaced. Therefore, optical changes induced by X-ray exposure can be correlated with X-ray diffraction data collection. The installation of Raman spectroscopy into the beamline is also briefly reviewed. Data are now routinely generated almost simultaneously from three complementary types of experiments from the same sample. The beamline is available now to the NSLS general user population.

  16. Identification of minority compounds in natural ilmenites by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Klepka, M.T.; Lawniczak-Jablonska, K.; Wolska, A.; Jablonski, M.

    2010-01-01

    Research highlights: → White pigment TiO 2 production process. → The principal component analysis using XANES. → Ilmenite accompanying chemical compounds identification. → Chemical binding of Mg in ilmenite depends on the climatic and geological conditions. -- Abstract: Natural ilmenites are used all over the world as raw materials in white pigment (TiO 2 ) production. Besides the FeTiO 3 in the raw material many other compounds are present. The chemical compounds based on the minority elements influence quality of the final product and are difficult to identify. The knowledge about chemical bonding of the minor elements enables to properly adjust chemical reactions during production processes and to improve quality of the final product. In this paper the X-ray absorption spectroscopy (XAS) identification of the chemical compounds formed by Mg, Mn and Cr in natural ilmenites originating from different places is presented.

  17. Structure-activity relationships of heterogeneous catalysts from time-resolved X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Ressler, T.; Jentoft, R.E.; Wienold, J.; Girgsdies, F.; Neisius, T.; Timpe, O.

    2003-01-01

    Knowing the composition and the evolution of the bulk structure of a heterogeneous catalyst under working conditions (in situ) is a pre-requisite for understanding structure-activity relationships. X-ray absorption spectroscopy can be employed to study a catalytically active material in situ. In addition to steady-state investigations, the technique permits experiments with a time-resolution in the sub-second range to elucidate the solid-state kinetics of the reactions involved. Combined with mass spectrometry, the evolution of the short-range order structure of a heterogeneous catalyst, the average valence of the constituent metals, and the phase composition can be obtained. Here we present results obtained from time-resolved studies on the reduction of MoO 3 in propene and in propene and oxygen

  18. Electronic topological transition in zinc under pressure: An x-ray absorption spectroscopy study

    International Nuclear Information System (INIS)

    Aquilanti, G.; Trapananti, A.; Pascarelli, S.; Minicucci, M.; Principi, E.; Liscio, F.; Twarog, A.

    2007-01-01

    Zinc metal has been studied at high pressure using x-ray absorption spectroscopy. In order to investigate the role of the different degrees of hydrostaticity on the occurrence of structural anomalies following the electronic topological transition, two pressure transmitting media have been used. Results show that the electronic topological transition, if it exists, does not induce an anomaly in the local environment of compressed Zn as a function of hydrostatic pressure and any anomaly must be related to a loss of hydrostaticity of the pressure transmitting medium. The near-edge structures of the spectra, sensitive to variations in the electronic density of states above the Fermi level, do not show any evidence of electronic transition whatever pressure transmitting medium is used

  19. Tin Valence and Local Environments in Silicate Glasses as Determined From X-ray Absorption Spectroscopy

    International Nuclear Information System (INIS)

    McKeown, D.; Buechele, A.; Gan, H.; Pegg, I.

    2008-01-01

    X-ray absorption spectroscopy (XAS) was used to characterize the tin (Sn) environments in four borosilicate glass nuclear waste formulations, two silicate float glasses, and three potassium aluminosilicate glasses. Sn K-edge XAS data of most glasses investigated indicate Sn4+O6 units with average Sn-O distances near 2.03 Angstroms. XAS data for a float glass fabricated under reducing conditions show a mixture of Sn4+O6 and Sn2+O4 sites. XAS data for three glasses indicate Sn-Sn distances ranging from 3.43 to 3.53 Angstroms, that suggest Sn4+O6 units linking with each other, while the 4.96 Angstroms Sn-Sn distance for one waste glass suggests clustering of unlinked Sn4+O6 units.

  20. X-ray absorption spectroscopy of PbMoO 4 single crystals

    Indian Academy of Sciences (India)

    X-ray absorption spectra of PbMoO4 (LMO) crystals have been investigated for the first time in literature. The measurements have been carried out at Mo absorption edge at the dispersive EXAFS beamline (BL-8) of INDUS-2 Synchrotron facility at Indore, India. The optics of the beamline was set to obtain a band of 2000 eV ...

  1. X-ray absorption spectroscopy in biological systems. Opportunities and limitations

    Energy Technology Data Exchange (ETDEWEB)

    Bovenkamp, Gudrun Lisa

    2013-05-15

    X-ray absorption spectroscopy has become more important for applications in the material sciences, geology, environmental science and biology, specifically in the field of molecular biology. The scope of this thesis is to add more experimental evidence in order to show how applicable X-ray absorption near edge structure (XANES) is to biology. Two biological systems were investigated, at the molecular level, lead uptake in plants and the effect of silver on bacteria. This investigation also included an analysis of the sensitivity of Pb L{sub 3}- and Ag L{sub 3}-XANES spectra with regard to their chemical environment. It was shown that Pb L{sub 3}- and Ag L{sub 3}-XANES spectra are sensitive to an environment with at least differences in the second coordination shell. The non-destructive and element specific properties of XANES are the key advantages that were very important for this investigation. However, in both projects the adequate selection of reference compounds, which required in some cases a chemical synthesis, was the critical factor to determine the chemical speciation and, finally, possible uptake and storage mechanisms for plants and antibacterial mechanisms of silver. The chemical environment of Pb in roots and leaves of plants from four different plant families and a lichen from a former lead mining site in the Eifel mountains in Germany was determined using both solid compounds and aqueous solutions of different ionic strength, which simulate the plant environment. The results can be interpreted in such a way that lead is sorbed on the surface of cell walls. Silver bonding as reaction with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli bacteria was determined using inorganic silver compounds and synthesized silver amino acids. Silver binds to sulfur, amine and carboxyl groups in amino acids.

  2. X-ray absorption spectroscopy in biological systems. Opportunities and limitations

    International Nuclear Information System (INIS)

    Bovenkamp, Gudrun Lisa

    2013-05-01

    X-ray absorption spectroscopy has become more important for applications in the material sciences, geology, environmental science and biology, specifically in the field of molecular biology. The scope of this thesis is to add more experimental evidence in order to show how applicable X-ray absorption near edge structure (XANES) is to biology. Two biological systems were investigated, at the molecular level, lead uptake in plants and the effect of silver on bacteria. This investigation also included an analysis of the sensitivity of Pb L 3 - and Ag L 3 -XANES spectra with regard to their chemical environment. It was shown that Pb L 3 - and Ag L 3 -XANES spectra are sensitive to an environment with at least differences in the second coordination shell. The non-destructive and element specific properties of XANES are the key advantages that were very important for this investigation. However, in both projects the adequate selection of reference compounds, which required in some cases a chemical synthesis, was the critical factor to determine the chemical speciation and, finally, possible uptake and storage mechanisms for plants and antibacterial mechanisms of silver. The chemical environment of Pb in roots and leaves of plants from four different plant families and a lichen from a former lead mining site in the Eifel mountains in Germany was determined using both solid compounds and aqueous solutions of different ionic strength, which simulate the plant environment. The results can be interpreted in such a way that lead is sorbed on the surface of cell walls. Silver bonding as reaction with Staphylococcus aureus, Listeria monocytogenes, and Escherichia coli bacteria was determined using inorganic silver compounds and synthesized silver amino acids. Silver binds to sulfur, amine and carboxyl groups in amino acids.

  3. X-ray absorption spectroscopy: EXAFS and XANES - A versatile tool to study the atomic and electronic structure of materials

    International Nuclear Information System (INIS)

    Alp, E.E.; Mini, S.M.; Ramanathan, M.

    1990-01-01

    X-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. The correct interpretation of the oscillatory structure in the x-ray absorption cross-section above the absorption edge has transformed XAS from a spectroscopic tool to a structural technique. EXAFS (Extended X-ray Absorption Fine Structure) yields information about the interatomic distances, near neighbor coordination numbers, and lattice dynamics. XANES (X-ray Absorption Near Edge Structure), on the other hand, gives information about the valence state, energy bandwidth and bond angles. Today, there are about 50 experimental stations in various synchrotrons around the world dedicated to collecting x-ray absorption data from the bulk and surfaces of solids and liquids. In this chapter, they will give the basic principles of XAS, explain the information content of essentially two different aspects of the absorption process leading to EXAFS and XANES, and discuss the source and sample limitations

  4. Optical and X-ray absorption spectroscopy in lead doped lithium fluoride crystals

    Energy Technology Data Exchange (ETDEWEB)

    Somma, F; Aloe, P; D' Acapito, F; Montereali, R M; Polosan, S; Secu, M; Vincenti, M A, E-mail: somma@fis.uniroma3.it

    2010-11-15

    LiF:Pb doped crystals were successfully grown by Kyropoulos method, starting with drying powders. The presence of Pb{sup 2+} ions in the LiF crystals were evidenced by the absorption band at 278 nm and by 375 nm photoluminescence. The presence of some other Pb structures with oxygen compounds in the as made samples was evidenced, decreasing after some annealing procedures. The local environment and valence state of Pb in LiF were studied by X-ray Absorption Spectroscopy at the Pb L{sub III} and L{sub I} edges. XANES data reveal that Pb is present as Pb{sup 2+} whereas EXAFS data show that it is incorporated in the crystal and not forming PbF{sub 2} precipitates. Identical spectra are obtained for samples as prepared and after thermal annealing up to 650 deg. C demonstrating the stability of the incorporation site. Also the concentration of Pb in the crystal has no effect on the location site of the metal as the same spectrum is obtained for specimens with different dopant concentrations.

  5. Electronic structure analysis of UO2 by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Ozkendir, O.M.

    2009-01-01

    Full text: Due to the essential role of Actinides in nuclear science and technology, electronic and structural investigations of actinide compounds attract major interest in science. Electronic structure of actinide compounds have important properties due to narrow 5f states which play key role in bonding with anions. The properties of Uranium has been a subject of enduring interest due to its being a major importance as a nuclear fuel and is the highest numbered element which can be found naturally on earth. UO 2 forms as a secondary uranyl group occurred during metamictization of uranium oxide compounds [1].Uranium oxide thin films have been investigated by X-ray Absorption Fine Structure spectroscopy (XAFS) [2]. The full multiple scattering approach has been applied to the calculation of U L3 edge spectra of UO 2 . The calculations are based on different choices of one electron potentials according to Uranium coordinations by using the real space multiple scattering method FEFF 8.2 code [3,4]. U L3-edge absorption spectrum in UO 2 is compared with U L3-edges in USiO 4 and UTe which are chosen due to their different electronic and chemical structures.We have found prominent changes in the XANES spectra of Uranium oxide thin films due to valency properties. Such observed changes are explained by considering the structural, electronic and spectroscopic properties. (author)

  6. X-ray absorption and Raman spectroscopy studies of molybdenum environments in borosilicate waste glasses

    Science.gov (United States)

    McKeown, David A.; Gan, Hao; Pegg, Ian L.

    2017-05-01

    Mo-containing high-level nuclear waste borosilicate glasses were investigated as part of an effort to improve Mo loading while avoiding yellow phase crystallization. Previous work showed that additions of vanadium decrease yellow phase formation and increases Mo solubility. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used to characterize Mo environments in HLW borosilicate glasses and to investigate possible structural relationships between Mo and V. Mo XAS spectra for the glasses indicate isolated tetrahedral Mo6+O4 with Mo-O distances near 1.75 Å. V XANES indicate tetrahedral V5+O4 as the dominant species. Raman spectra show composition dependent trends, where Mo-O symmetrical stretch mode frequencies (ν1) are sensitive to the mix of alkali and alkaline earth cations, decreasing by up to 10 cm-1 for glasses that change from Li+ to Na+ as the dominant network-modifying species. This indicates that MoO4 tetrahedra are isolated from the borosilicate network and are surrounded, at least partly, by Na+ and Li+. Secondary ν1 frequency effects, with changes up to 7 cm-1, were also observed with increasing V2O5 and MoO3 content. These secondary trends may indicate MoO4-MoO4 and MoO4-VO4 clustering, suggesting that V additions may stabilize Mo in the matrix with respect to yellow phase formation.

  7. Transport Measurements and Synchrotron-Based X-Ray Absorption Spectroscopy of Iron Silicon Germanide Grown by Molecular Beam Epitaxy

    Science.gov (United States)

    Elmarhoumi, Nader; Cottier, Ryan; Merchan, Greg; Roy, Amitava; Lohn, Chris; Geisler, Heike; Ventrice, Carl, Jr.; Golding, Terry

    2009-03-01

    Some of the iron-based metal silicide and germanide phases have been predicted to be direct band gap semiconductors. Therefore, they show promise for use as optoelectronic materials. We have used synchrotron-based x-ray absorption spectroscopy to study the structure of iron silicon germanide films grown by molecular beam epitaxy. A series of Fe(Si1-xGex)2 thin films (2000 -- 8000å) with a nominal Ge concentration of up to x = 0.04 have been grown. X-ray absorption near edge structure (XANES) and extended x-ray absorption fine structure (EXAFS) measurements have been performed on the films. The nearest neighbor co-ordination corresponding to the β-FeSi2 phase of iron silicide provides the best fit with the EXAFS data. Temperature dependent (20 coefficient was calculated. Results suggest semiconducting behavior of the films which is consistent with the EXAFS results.

  8. K-edge x-ray-absorption spectroscopy of laser-generated Kr+ and Kr2+

    International Nuclear Information System (INIS)

    Southworth, S. H.; Arms, D. A.; Dufresne, E. M.; Dunford, R. W.; Ederer, D. L.; Hoehr, C.; Kanter, E. P.; Kraessig, B.; Landahl, E. C.; Peterson, E. R.; Rudati, J.; Santra, R.; Walko, D. A.; Young, L.

    2007-01-01

    Tunable, polarized, microfocused x-ray pulses were used to record x-ray absorption spectra across the K edges of Kr + and Kr 2+ produced by laser ionization of Kr. Prominent 1s→4p and 5p excitations are observed below the 1s ionization thresholds in accord with calculated transition energies and probabilities. Due to alignment of 4p hole states in the laser-ionization process, the Kr + 1s→4p cross section varies with respect to the angle between the laser and x-ray polarization vectors. This effect is used to determine the Kr + 4p 3/2 and 4p 1/2 quantum state populations, and these are compared with results of an adiabatic strong-field ionization theory that includes spin-orbit coupling

  9. Structural investigations of LiFePO4 electrodes and in situ studies by Fe X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Deb, Aniruddha; Bergmann, Uwe; Cramer, S.P.; Cairns, Elton J.

    2005-01-01

    Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on electrodes containing LiFePO 4 to determine the local atomic and electronic structure and their stability with electrochemical cycling. A versatile electrochemical in situ cell has been constructed for long-term soft and hard X-ray experiments for the structural investigation on battery electrodes during the lithium-insertion/extraction processes. The device is used here for an X-ray absorption spectroscopic study of lithium insertion/extraction in a LiFePO 4 electrode, where the electrode contained about 7.7 mg of LiFePO 4 on a 20 μm thick Al-foil. Fe K-edge X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) have been performed on this electrode to determine the local atomic and electronic structure and their stability with electrochemical cycling. The initial state (LiFePO 4 ) showed iron to be in the Fe 2+ state corresponding to the initial state (0.0 mAh) of the cell, whereas in the delithiated state (FePO 4 ) iron was found to be in the Fe 3+ state corresponding to the final charged state (3 mAh). XANES region of the XAS spectra revealed a high spin configuration for the two states (Fe (II), d 6 and Fe (III), d 5 ). The results confirm that the olivine structure of the LiFePO 4 and FePO 4 is retained by the electrodes in agreement with the XRD observations reported previously. These results confirm that LiFePO 4 cathode material retains good structural short-range order leading to superior cycling capability

  10. X-ray absorption spectroscopy study on the thermal and hydrazine reduction of graphene oxide

    International Nuclear Information System (INIS)

    Liang, Xianqing; Wang, Yu; Zheng, Huiyuan; Wu, Ziyu

    2014-01-01

    Highlights: • XAS study of GO and reduced GO was performed. • Detailed evolution of the electronic structures and chemical bonding of GO was revealed. • A new efficient route for the reduction of GO is proposed. - Abstract: X-ray absorption spectroscopy (XAS) was applied to systemically investigate the deoxygenation of graphene oxide (GO) via annealing and hydrazine treatment. Detailed evolution of the electronic structures and chemical bonding of GO was presented. The enhanced intensity of π * resonance and the appearance of splitting σ * resonance in C K-edge XAS spectra suggest high extents of recoveries of π-conjugation upon reduction using thermal annealing or hydrazine. Experimental results revealed that the carboxyl as well as epoxide and hydroxyl groups on the surface of GO were thermally reduced first, followed by the more difficult removal of carbonyl and cyclic ether groups at higher temperatures. The hydrazine reduction could remove epoxide, hydroxyl and carboxyl groups effectively, whereas the carbonyl groups were partially reduced with the incorporation of nitrogen species simultaneously. The residual oxygen functional groups on hydrazine-reduced GO could be further removed after modest thermal annealing. It was proposed that a combination of both types of reductions would give the best deoxygenation efficiency for the production of graphene

  11. Speciation of Selenium in Stream Insects Using X-Ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Andrahennadi, R.; Wayland, M.; Pickering, I.J.

    2009-05-28

    Selenium contamination in the environment is a widespread problem affecting insects and other wildlife. Insects occupy a critical middle link and aid in trophic transfer of selenium in many terrestrial and freshwater food chains, but the mechanisms of selenium uptake through the food chain are poorly understood. In particular, biotransformation of selenium by insects into different chemical forms will greatly influence how toxic or benign the selenium is to that organism or to its predators. We have used X-ray absorption spectroscopy (XAS) to identify the chemical form of selenium in insects inhabiting selenium contaminated streams near Hinton, Alberta (Canada). Selenium K near-edge spectra indicate a variability of selenium speciation among the insects that included mayflies (Ephemeroptera), stoneflies (Plecoptera), caddisflies (Trichoptera), and craneflies (Diptera). Higher percentages of inorganic selenium were observed in primary consumers, detritivores, and filter feeders than in predatory insects. Among the organic forms of selenium, organic selenides constituted a major fraction in most organisms. A species modeled as trimethylselenonium was observed during the pupal stage of caddisflies. These results provide insights into how the insects cope with their toxic cargo, including how the selenium is biotransformed into less toxic forms and how it can be eliminated from the insects. More broadly, this study demonstrates the strengths of XAS to probe the effects of heavy elements at trace levels in insects from the field.

  12. Speciation of selenium in stream insects using X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ruwandi Andrahennadi; Mark Wayland; Ingrid J. Pickering [University of Saskatchewan, Saskatoon, SK (Canada). Department of Geological Sciences

    2007-11-15

    Selenium contamination in the environment is a widespread problem affecting insects and other wildlife. Insects occupy a critical middle link and aid in trophic transfer of selenium in many terrestrial and freshwater food chains, but the mechanisms of selenium uptake through the food chain are poorly understood. In particular, biotransformation of selenium by insects into different chemical forms will greatly influence how toxic or benign the selenium is to that organism or to its predators. We have used X-ray absorption spectroscopy (XAS) to identify the chemical form of selenium in insects inhabiting selenium contaminated streams near Hinton, Alberta (Canada). Selenium K near-edge spectra indicate a variability of selenium speciation among the insects that included mayflies (Ephemeroptera), stoneflies (Plecoptera), caddisflies (Trichoptera), and craneflies (Diptera). Higher percentages of inorganic selenium were observed in primary consumers, detritivores, and filter feeders than in predatory insects. Among the organic forms of selenium, organic selenides constituted a major fraction in most organisms. A species modeled as trimethylselenonium was observed during the pupal stage of caddisflies. These results provide insights into how the insects cope with their toxic cargo, including how the selenium is biotransformed into less toxic forms and how it can be eliminated from the insects. More broadly, this study demonstrates the strengths of XAS to probe the effects of heavy elements at trace levels in insects from the field.

  13. Properties of aqueous nitrate and nitrite from x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Smith, Jacob W.; Lam, Royce K.; Saykally, Richard J., E-mail: saykally@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Shih, Orion [National Synchrotron Radiation Research Center, Hsinchu 30076, Taiwan (China); Rizzuto, Anthony M. [Department of Chemistry, University of California, Berkeley, California 94720 (United States); Prendergast, David [The Molecular Foundry, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2015-08-28

    Nitrate and nitrite ions are of considerable interest, both for their widespread use in commercial and research contexts and because of their central role in the global nitrogen cycle. The chemistry of atmospheric aerosols, wherein nitrate is abundant, has been found to depend on the interfacial behavior of ionic species. The interfacial behavior of ions is determined largely by their hydration properties; consequently, the study of the hydration and interfacial behavior of nitrate and nitrite comprises a significant field of study. In this work, we describe the study of aqueous solutions of sodium nitrate and nitrite via X-ray absorption spectroscopy (XAS), interpreted in light of first-principles density functional theory electronic structure calculations. Experimental and calculated spectra of the nitrogen K-edge XA spectra of bulk solutions exhibit a large 3.7 eV shift between the XA spectra of nitrate and nitrite resulting from greater stabilization of the nitrogen 1s energy level in nitrate. A similar shift is not observed in the oxygen K-edge XA spectra of NO{sub 3}{sup −} and NO{sub 2}{sup −}. The hydration properties of nitrate and nitrite are found to be similar, with both anions exhibiting a similar propensity towards ion pairing.

  14. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    Energy Technology Data Exchange (ETDEWEB)

    Isomura, Noritake, E-mail: isomura@mosk.tytlabs.co.jp [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Soejima, Narumasa; Iwasaki, Shiro [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan); Nomoto, Toyokazu; Murai, Takaaki [Aichi Synchrotron Radiation Center (AichiSR), 250-3 Minamiyamaguchi-cho, Seto, Aichi 489-0965 (Japan); Kimoto, Yasuji [Toyota Central R& D Labs., Inc., 41-1 Yokomichi, Nagakute, Aichi 480-1192 (Japan)

    2015-11-15

    Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si{sub 3}N{sub 4}/SiO{sub 2}/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si{sub 3}N{sub 4}/SiO{sub 2}/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  15. Depth-selective X-ray absorption spectroscopy by detection of energy-loss Auger electrons

    International Nuclear Information System (INIS)

    Isomura, Noritake; Soejima, Narumasa; Iwasaki, Shiro; Nomoto, Toyokazu; Murai, Takaaki; Kimoto, Yasuji

    2015-01-01

    Graphical abstract: - Highlights: • A unique XAS method is proposed for depth profiling of chemical states. • PEY mode detecting energy-loss electrons enables a variation in the probe depth. • Si K-edge XAS spectra of the Si_3N_4/SiO_2/Si multilayer films have been investigated. • Deeper information was obtained in the spectra measured at larger energy loss. • Probe depth could be changed by the selection of the energy of detected electrons. - Abstract: A unique X-ray absorption spectroscopy (XAS) method is proposed for depth profiling of chemical states in material surfaces. Partial electron yield mode detecting energy-loss Auger electrons, called the inelastic electron yield (IEY) mode, enables a variation in the probe depth. As an example, Si K-edge XAS spectra for a well-defined multilayer sample (Si_3N_4/SiO_2/Si) have been investigated using this method at various kinetic energies. We found that the peaks assigned to the layers from the top layer to the substrate appeared in the spectra in the order of increasing energy loss relative to the Auger electrons. Thus, the probe depth can be changed by the selection of the kinetic energy of the energy loss electrons in IEY-XAS.

  16. Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lam, Royce K.; Smith, Jacob W.; Saykally, Richard J., E-mail: saykally@berkeley.edu [Department of Chemistry, University of California, Berkeley, California 94720, USA and Chemical Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States)

    2016-05-21

    While methanol and ethanol are macroscopically miscible with water, their mixtures exhibit negative excess entropies of mixing. Despite considerable effort in both experiment and theory, there remains significant disagreement regarding the origin of this effect. Different models for the liquid mixture structure have been proposed to address this behavior, including the enhancement of the water hydrogen bonding network around the alcohol hydrophobic groups and microscopic immiscibility or clustering. We have investigated mixtures of methanol, ethanol, and isopropanol with water by liquid microjet X-ray absorption spectroscopy on the oxygen K-edge, an atom-specific probe providing details of both inter- and intra-molecular structure. The measured spectra evidence a significant enhancement of hydrogen bonding originating from the methanol and ethanol hydroxyl groups upon the addition of water. These additional hydrogen bonding interactions would strengthen the liquid-liquid interactions, resulting in additional ordering in the liquid structures and leading to a reduction in entropy and a negative enthalpy of mixing, consistent with existing thermodynamic data. In contrast, the spectra of the isopropanol-water mixtures exhibit an increase in the number of broken alcohol hydrogen bonds for mixtures containing up to 0.5 water mole fraction, an observation consistent with existing enthalpy of mixing data, suggesting that the measured negative excess entropy is a result of clustering or micro-immiscibility.

  17. Communication: Hydrogen bonding interactions in water-alcohol mixtures from X-ray absorption spectroscopy

    Science.gov (United States)

    Lam, Royce K.; Smith, Jacob W.; Saykally, Richard J.

    2016-05-01

    While methanol and ethanol are macroscopically miscible with water, their mixtures exhibit negative excess entropies of mixing. Despite considerable effort in both experiment and theory, there remains significant disagreement regarding the origin of this effect. Different models for the liquid mixture structure have been proposed to address this behavior, including the enhancement of the water hydrogen bonding network around the alcohol hydrophobic groups and microscopic immiscibility or clustering. We have investigated mixtures of methanol, ethanol, and isopropanol with water by liquid microjet X-ray absorption spectroscopy on the oxygen K-edge, an atom-specific probe providing details of both inter- and intra-molecular structure. The measured spectra evidence a significant enhancement of hydrogen bonding originating from the methanol and ethanol hydroxyl groups upon the addition of water. These additional hydrogen bonding interactions would strengthen the liquid-liquid interactions, resulting in additional ordering in the liquid structures and leading to a reduction in entropy and a negative enthalpy of mixing, consistent with existing thermodynamic data. In contrast, the spectra of the isopropanol-water mixtures exhibit an increase in the number of broken alcohol hydrogen bonds for mixtures containing up to 0.5 water mole fraction, an observation consistent with existing enthalpy of mixing data, suggesting that the measured negative excess entropy is a result of clustering or micro-immiscibility.

  18. Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Fan, Jian-Xin [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); School of River and Ocean Engineering, Chongqing Jiaotong University, Chongqing 400074 (China); Wang, Yu-Jun, E-mail: yjwang@issas.ac.cn [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Liu, Cun [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Wang, Li-Hua; Yang, Ke [Synchrotron Radiation Facility, Shanghai Institute of Applied Physics, Chinese Academy of sciences, Shanghai 201204 (China); Zhou, Dong-Mei, E-mail: dmzhou@issas.ac.cn [Key Laboratory of Soil Environment and Pollution Remediation, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008 (China); Li, Wei; Sparks, Donald L. [Environmental Soil Chemistry Group, Delaware Environmental Institute and Department of Plant and Soil Sciences, University of Delaware, Newark, DE 19717-1303 United States (United States)

    2014-08-30

    Graphical abstract: - Highlights: • Immobility and transformation of As on different Eh soils were investigated. • μ-XRF, XANES, and XPS were used to gain As distribution and speciation in soil. • Sorption capacity of As on anaerobic soil was much higher than that on oxic soil. • Fe oxides reductive dissolution is a key factor for As sorption and transformation. - Abstract: The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (μ-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (μ-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils.

  19. Effect of iron oxide reductive dissolution on the transformation and immobilization of arsenic in soils: New insights from X-ray photoelectron and X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Fan, Jian-Xin; Wang, Yu-Jun; Liu, Cun; Wang, Li-Hua; Yang, Ke; Zhou, Dong-Mei; Li, Wei; Sparks, Donald L.

    2014-01-01

    Graphical abstract: - Highlights: • Immobility and transformation of As on different Eh soils were investigated. • μ-XRF, XANES, and XPS were used to gain As distribution and speciation in soil. • Sorption capacity of As on anaerobic soil was much higher than that on oxic soil. • Fe oxides reductive dissolution is a key factor for As sorption and transformation. - Abstract: The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (μ-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (μ-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils

  20. Near edge x-ray spectroscopy theory

    International Nuclear Information System (INIS)

    1994-01-01

    We propose to develop a quantitative theory of x-ray spectroscopies in the near edge region, within about 100 eV of threshold. These spectroscopies include XAFS (X-ray absorption fine structure), photoelectron diffraction (PD), and diffraction anomalous fine structure (DAFS), all of which are important tools for structural studies using synchrotron radiation x-ray sources. Of primary importance in these studies are many-body effects, such as the photoelectron self-energy, and inelastic losses. A better understanding of these quantities is needed to obtain theories without adjustable parameters. We propose both analytical and numerical calculations, the latter based on our x-ray spectroscopy codes FEFF

  1. A reaction cell with sample laser heating for in situ soft X-ray absorption spectroscopy studies under environmental conditions.

    Science.gov (United States)

    Escudero, Carlos; Jiang, Peng; Pach, Elzbieta; Borondics, Ferenc; West, Mark W; Tuxen, Anders; Chintapalli, Mahati; Carenco, Sophie; Guo, Jinghua; Salmeron, Miquel

    2013-05-01

    A miniature (1 ml volume) reaction cell with transparent X-ray windows and laser heating of the sample has been designed to conduct X-ray absorption spectroscopy studies of materials in the presence of gases at atmospheric pressures. Heating by laser solves the problems associated with the presence of reactive gases interacting with hot filaments used in resistive heating methods. It also facilitates collection of a small total electron yield signal by eliminating interference with heating current leakage and ground loops. The excellent operation of the cell is demonstrated with examples of CO and H2 Fischer-Tropsch reactions on Co nanoparticles.

  2. Combining selective sequential extractions, X-Ray Absorption Spectroscopy, and X-Ray Powder Diffraction for Cu (II speciation in soil and mineral phases

    Directory of Open Access Journals (Sweden)

    Tatiana Minkina

    2017-04-01

    Full Text Available Interaction of Cu (II ions with the matrix of soil and mineral phases of layered silicates was assessed by the Miller method of selective sequential fractionation and a set of synchrotron X-ray methods, including X-ray powder diffraction (XRD and X-ray absorption spectroscopy (XANES. It was shown that the input of Cu into Calcic Chernozem in the form of monoxide (CuO and salt (Cu(NO32 affected the transformation of Cu compounds and their affinity for metal-bearing phases. It was found that the contamination of soil with a soluble Cu(II salt increased the bioavailability of the metal and the role of organic matter and Fe oxides in the fixation and retention of Cu. During the incubation of soil with Cu monoxide, the content of the metal in the residual fractions increased, which was related to the possible entry of Cu in the form of isomorphic impurities into silicates, as well as to the incomplete dissolution of exogenic compounds at the high level of their input into the soil. A mechanism for the structural transformation of minerals was revealed, which showed that ion exchange processes result in the sorption of Cu (II ions from the saturated solution by active sites on the internal surface of the lattice of dioctahedral aluminosilicates. Surface hydroxyls at the octahedral aluminum atom play the main role. X-ray diagnostics revealed that excess Cu(II ions are removed from the system due to the formation and precipitation of coarsely crystalline Cu(NO3(OH3.

  3. Extended x-ray absorption fine structure spectroscopy and x-ray absorption near edge spectroscopy study of aliovalent doped ceria to correlate local structural changes with oxygen vacancies clustering

    Energy Technology Data Exchange (ETDEWEB)

    Shirbhate, S. C.; Acharya, S. A., E-mail: saha275@yahoo.com [Department of Physics, Rashtrasant Tukadoji Maharaj Nagpur University, Nagpur 440033 (India); Yadav, A. K. [Atomic and molecular Physics Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2016-04-04

    This study provides atomic scale insight to understand the role of aliovalent dopants on oxygen vacancies clustering and dissociation mechanism in ceria system in order to enhance the performance of oxy-ion conductor. Dopants induced microscale changes in ceria are probed by extended X-ray absorption fine structure spectroscopy, X-ray absorption near edge spectra, and Raman spectroscopy. The results are explored to establish a correlation between atomic level structural changes (coordination number, interatomic spacing) → formation of dimer and trimer type cation-oxygen vacancies defect complex (intrinsic and extrinsic) → dissociation of oxygen vacancies from defect cluster → ionic conductivity temperature. It is a strategic approach to understand key physics of ionic conductivity mechanism in order to reduce operating temperature of electrolytes for intermediate temperature (300–450 °C) electrochemical devices for the first time.

  4. Bimetallic Catalysts and Platinum Surfaces Studied by X-ray Absorption Spectroscopy and Scanning Tunnelling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roenning, Magnus

    2000-07-01

    Bimetallic catalyst systems used in Fischer-Tropsch synthesis (Co-Re/Al{sub 2}O{sub 3}) and in the naphtha reforming process (Pt-Re/Al{sub 2}O{sub 3}) have been studied in situ using X-ray absorption spectroscopy (EXAFS). Additionally, the adsorption of ethene on platinum single crystal surfaces has been investigated using scanning tunnelling microscopy. In situ EXAFS at the cobalt K absorption edge have been carried out at 450{sup o}C on the hydrogen reduction of a rhenium-promoted Co{sub 3}O{sub 4}/Al{sub 2}O{sub 3} catalyst. Reductions carried out using 100% hydrogen and 5% hydrogen in helium gave different results. Whereas the reduction using dilute hydrogen leads to bulk-like metallic cobalt particles (hcp or fcc), reaction with pure hydrogen yields a more dispersed system with smaller cobalt metal particles (< 40 A). The results are rationalised in terms of different degrees of reoxidation of cobalt by the higher and lower concentrations of water generated during the reduction of cobalt oxide by 100% and 5% hydrogen, respectively. Additionally, in both reduction protocols a small fraction (3 -4 wt%) of the cobalt content is randomly dispersed over the tetrahedral vacancies of the alumina support. This dispersion occurs during reduction and not calcination. The cobalt in these sites cannot be reduced at 450 {sup o}C. The local environments about the rhenium atoms in Co-Re/{gamma}-A1{sub 2}O{sub 3} catalyst after different reduction periods have been studied by X-ray absorption spectroscopy. A bimetallic catalyst containing 4.6 wt% cobalt and 2 wt% rhenium has been compared with a corresponding monometallic sample with 2 wt% rhenium on the same support. The rhenium L{sub III} EXAFS analysis shows that bimetallic particles are formed after reduction at 450{sup o}C with the average particle size being 10-15 A. Rhenium is shown to be reduced at a later stage than cobalt. The fraction of cobalt atoms entering the support obstructs the access to the support for the

  5. Determination of copper binding in Pseudomonas putida CZ1 by chemical modifications and X-ray absorption spectroscopy.

    Science.gov (United States)

    Chen, XinCai; Shi, JiYan; Chen, YingXu; Xu, XiangHua; Chen, LiTao; Wang, Hui; Hu, TianDou

    2007-03-01

    Previously performed studies have shown that Pseudomonas putida CZ1 biomass can bind an appreciable amount of Cu(II) and Zn(II) ions from aqueous solutions. The mechanisms of Cu- and Zn-binding by P. putida CZ1 were ascertained by chemical modifications of the biomass followed by Fourier transform infrared and X-ray absorption spectroscopic analyses of the living or nonliving cells. A dramatic decrease in Cu(II)- and Zn(II)-binding resulted after acidic methanol esterification of the nonliving cells, indicating that carboxyl functional groups play an important role in the binding of metal to the biomaterial. X-ray absorption spectroscopy was used to determine the speciation of Cu ions bound by living and nonliving cells, as well as to elucidate which functional groups were involved in binding of the Cu ions. The X-ray absorption near-edge structure spectra analysis showed that the majority of the Cu was bound in both samples as Cu(II). The fitting results of Cu K-edge extended X-ray absorption fine structure spectra showed that N/O ligands dominated in living and nonliving cells. Therefore, by combining different techniques, our results indicate that carboxyl functional groups are the major ligands responsible for the metal binding in P. putida CZ1.

  6. Challenges for energy dispersive X-ray absorption spectroscopy at the ESRF: microsecond time resolution and Mega-bar pressures

    International Nuclear Information System (INIS)

    Aquilanti, G.

    2002-01-01

    This Thesis concerns the development of two different applications of energy-dispersive X-ray absorption spectroscopy at the ESRF: time-resolved studies pushed to the microsecond time resolution and high-pressure studies at the limit of the Mega-bar pressures. The work has been developed in two distinct parts, and the underlying theme has been the exploitation of the capabilities of an X-ray absorption spectrometer in dispersive geometry on a third generation synchrotron source. For time-resolved studies, the study of the triplet excited state following a laser excitation of Pt 2 (P 2 O 5 H 2 ) 4 4- has been chosen to push the technique to the microsecond time resolution. In the high-pressure part, the suitability of the energy dispersive X-ray absorption spectrometer for high-pressure studies using diamond anvils cell is stressed. Some technical developments carried out on beamline ID24 are discussed. Finally, the most extensive scientific part concerns a combined X-ray absorption and diffraction study of InAs under pressure. (author)

  7. Molecular characterization of copper in soils using X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Strawn, Daniel G.; Baker, Leslie L.

    2009-01-01

    Bioavailability of Cu in the soil is a function of its speciation. In this paper we investigated Cu speciation in six soils using X-ray absorption near edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and synchrotron-based micro X-ray fluorescence (μ-XRF). The XANES and EXAFS spectra in all of the soils were the same. μ-XRF results indicated that the majority of the Cu particles in the soils were not associated with calcium carbonates, Fe oxides, or Cu sulfates. Principal component analysis and target transform of the XANES and EXAFS spectra suggested that Cu adsorbed on humic acid (HA) was an acceptable match. Thus it appears that Cu in all of the soils is primarily associated with soil organic matter (SOM). Theoretical fitting of the molecular structure in the soil EXAFS spectra revealed that the Cu in the soils existed as Cu atoms bound in a bidentate complex to O or N functional groups. - Copper speciation in six soils was investigated using XANES, EXAFS, and μ-XRF.

  8. Time-resolved pump and probe x-ray absorption fine structure spectroscopy at beamline P11 at PETRA III

    Energy Technology Data Exchange (ETDEWEB)

    Göries, D., E-mail: dennis.goeries@desy.de; Roedig, P.; Stübe, N.; Meyer, J.; Warmer, M.; Weckert, E.; Meents, A., E-mail: alke.meents@desy.de [DESY Photon Science, Deutsches Elektronen-Synchrotron (DESY), Notkestraße 85, 22607 Hamburg (Germany); Dicke, B.; Naumova, M.; Rübhausen, M. [Center for Free-Electron Laser Science (CFEL), Luruper Chaussee 149, 22761 Hamburg (Germany); Galler, A.; Gawelda, W.; Geßler, P.; Sotoudi Namin, H.; Beckmann, A. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); Britz, A.; Bressler, C. [European XFEL, Albert-Einstein Ring 19, 22761 Hamburg (Germany); The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg (Germany); Schlie, M. [Institut für Experimentalphysik, University of Hamburg, Luruper Chaussee 149, 22761 Hamburg (Germany)

    2016-05-15

    We report about the development and implementation of a new setup for time-resolved X-ray absorption fine structure spectroscopy at beamline P11 utilizing the outstanding source properties of the low-emittance PETRA III synchrotron storage ring in Hamburg. Using a high intensity micrometer-sized X-ray beam in combination with two positional feedback systems, measurements were performed on the transition metal complex fac-Tris[2-phenylpyridinato-C2,N]iridium(III) also referred to as fac-Ir(ppy){sub 3}. This compound is a representative of the phosphorescent iridium(III) complexes, which play an important role in organic light emitting diode (OLED) technology. The experiment could directly prove the anticipated photoinduced charge transfer reaction. Our results further reveal that the temporal resolution of the experiment is limited by the PETRA III X-ray bunch length of ∼103 ps full width at half maximum (FWHM).

  9. Local structure near actinides and nucleating elements in borosilicate glass for nuclear industry: Results of X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Petit-Maire, D.

    1988-01-01

    Possibilities and limits of X-ray absorption spectroscopy for cation site description in silicate glasses and possible applications for complex glasses, like glass for fission product containment, are examined. In borosilicate glasses two types of sites are evidenced for actinides at the valence 4: Coordinance 6 sites with a narrow radial distribution for the distance An-0; higher coordination (7, 8 or more) with a wider and asymmetrical radial distribution. Proportion of low coordinance sites increases when cation size decreases (Th > Np). U and Np VI and V are characterized as actinyles with a chain 0-An-0 practically linear, coordinance in a plane perpendicular to this complex is probably 5. X-ray absorption spectroscopy allows an accurate description of actinide sites in fission product glasses [fr

  10. Time-resolved X-ray absorption spectroscopy for laser-ablated silicon particles in xenon gas

    International Nuclear Information System (INIS)

    Makimura, Tetsuya; Sakuramoto, Tamaki; Murakami, Kouichi

    1996-01-01

    We developed a laboratory-scale in situ apparatus for soft X-ray absorption spectroscopy with a time resolution of 10 ns and a space resolution of 100 μm. Utilizing this spectrometer, we have investigated the dynamics of silicon atoms formed by laser ablation in xenon gas. It was found that 4d-electrons in the xenon atoms are excited through collision with electrons in the laser-generated silicon plasma. (author)

  11. X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Attekum, P.M.T.M. van.

    1979-01-01

    The methods and results of X-ray photoelectron spectroscopy in the study of plasmons, alloys and gold compounds are discussed. After a comprehensive introduction, seven papers by the author, previously published elsewhere, are reprinted and these cover a wide range of the uses of X-ray photoelectron spectroscopy. (W.D.L.)

  12. X-ray absorption and Raman spectroscopy studies of molybdenum environments in borosilicate waste glasses

    Energy Technology Data Exchange (ETDEWEB)

    McKeown, David A., E-mail: davidm@vsl.cua.edu; Gan, Hao; Pegg, Ian L.

    2017-05-15

    Mo-containing high-level nuclear waste borosilicate glasses were investigated as part of an effort to improve Mo loading while avoiding yellow phase crystallization. Previous work showed that additions of vanadium decrease yellow phase formation and increases Mo solubility. X-ray absorption spectroscopy (XAS) and Raman spectroscopy were used to characterize Mo environments in HLW borosilicate glasses and to investigate possible structural relationships between Mo and V. Mo XAS spectra for the glasses indicate isolated tetrahedral Mo{sup 6+}O{sub 4} with Mo-O distances near 1.75 Å. V XANES indicate tetrahedral V{sup 5+}O{sub 4} as the dominant species. Raman spectra show composition dependent trends, where Mo-O symmetrical stretch mode frequencies (ν{sub 1}) are sensitive to the mix of alkali and alkaline earth cations, decreasing by up to 10 cm{sup −1} for glasses that change from Li{sup +} to Na{sup +} as the dominant network-modifying species. This indicates that MoO{sub 4} tetrahedra are isolated from the borosilicate network and are surrounded, at least partly, by Na{sup +} and Li{sup +}. Secondary ν{sub 1} frequency effects, with changes up to 7 cm{sup −1}, were also observed with increasing V{sub 2}O{sub 5} and MoO{sub 3} content. These secondary trends may indicate MoO{sub 4}-MoO{sub 4} and MoO{sub 4}-VO{sub 4} clustering, suggesting that V additions may stabilize Mo in the matrix with respect to yellow phase formation. - Highlights: •Raman and XAS data indicate isolated MoO{sub 4} tetrahedra from the borosilicate network. •Mo-O stretch frequency is sensitive to network-modifying Li and Na concentrations. •Mo-O stretch frequency shifts were also seen with increasing V{sub 2}O{sub 5} and MoO{sub 3} content. •The Raman trends may indicate MoO{sub 4}-MoO{sub 4} and MoO{sub 4}-VO{sub 4} clustering in the glass. •V may stabilize Mo in the glass matrix avoiding yellow phase formation.

  13. Insight into the structure of Pd/ZrO2 during the total oxidation of methane using combined in situ XRD, X.-ray absorption and Raman spectroscopy

    DEFF Research Database (Denmark)

    Grunwaldt, Jan-Dierk; van Vegten, Niels; Baiker, Alfons

    2009-01-01

    The structure of palladium during the total combustion of methane has been studied by a combination of the complementary in situ techniques X-ray absorption spectroscopy, Raman spectroscopy and X-ray diffraction. The study demonstrates that finely dispersed and oxidized palladium is most active f...

  14. A laser heating facility for energy-dispersive X-ray absorption spectroscopy

    DEFF Research Database (Denmark)

    Kantor, Innokenty; Marini, C.; Mathon, O.

    2018-01-01

    A double-sided laser heating setup for diamond anvil cells installed on the ID24 beamline of the ESRF is presented here. The setup geometry is specially adopted for the needs of energy-dispersive X-ray absorption spectroscopic (XAS) studies of materials under extreme pressure and temperature...... conditions. We illustrate the performance of the facility with a study on metallic nickel at 60 GPa. The XAS data provide the temperature of the melting onset and quantitative information on the structural parameters of the first coordination shell in the hot solid up to melting....

  15. Extension to Low Energies (<7keV) of High Pressure X-Ray Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Itie, J.-P.; Flank, A.-M.; Lagarde, P.; Idir, M.; Polian, A.; Couzinet, B.

    2007-01-01

    High pressure x-ray absorption has been performed down to 3.6 keV, thanks to the new LUCIA beamline (SLS, PSI) and to the use of perforated diamonds or Be gasket. Various experimental geometries are proposed, depending on the energy of the edge and on the concentration of the studied element. A few examples will be presented: BaTiO3 at the titanium K edge, Zn0.95 Mn0.05O at the manganese K edge, KCl at the potassium K edge

  16. The aquatic hyphomycete Heliscus lugdunensis protects its hyphae tip cells from cadmium: A micro X-ray fluorescence and X-ray absorption near edge structure spectroscopy study

    Science.gov (United States)

    Isaure, Marie-Pierre; Leyh, Benjamin; Salomé, Murielle; Krauss, Gerd-Joachim; Schaumlöffel, Dirk; Dobritzsch, Dirk

    2017-11-01

    Aquatic fungi can be used to evaluate the functioning of natural ecosystems. Heliscus lugdunensis is an early colonizer of allochthone leafs. Since this aquatic hyphomycete is able to develop in metal contaminated habitats and tolerates cadmium, it appears to be a good candidate to investigate adaptation to metal pollution. This study aimed at examining the sequestration of Cd in the hyphae of H. lugdunensis, and particularly the role of the tip cells. For that, H. lugdunensis growth was evaluated under various Cd concentrations, and a combination of synchrotron micro X-ray fluorescence and X-ray absorption near edge structure spectroscopy was carried out to determine the compartments of Cd accumulation and the Cd chemical species, respectively. Results showed that the hyphal tip cells were depleted in Cd, and that the metal was stored in older cells. Cd was mainly associated with sulfur ligands and to a lesser extent bound to phosphates and carboxyl/hydroxyl groups from cell wall and/or organic acids. Finally, the aquatic fungus was able to maintain the tip cell as a functional system, thus allowing the colonization of contaminated environments.

  17. Investigation of annealed and metamict pyrochlore minerals by x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Greegor, R.B.; Lytle, F.W.; Ewing, R.C.; Chakoumakos, B.C.; Lumpkin, G.R.

    1984-01-01

    Materials of the pyrochlore structure type exhibit a variety of interesting properties including phases capable of acting as hosts for actinides in radioactive wastes. Studies of curium doped gadolinium titanate phases (Gd 2 Ti 2 O 7 ) have been made which showed that the radiation damage ingrowth followed an exponential relationship. For the study reported here a series of synthetic pyrochlores were produced having the titanate phase with the general formula (RE) 2 Ti 2 O 7 , RE = Er, Y 2 , Gd 2 , Dy, La. Additionally a set of metamict (radiation damaged) pyrochlores was examined in both a natural and post temperature annealed state. Experiments were conducted on these samples using the Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES) techniques. In summary, these studies show that in pyrochlore structure types the Ti-O cage undergoes changes due to radiation damage. The individual Ti-O bonds become more disordered which leads to a loss of short and long range order and, ultimately, to expansion of the bulk material. 2 refs., 2 figs

  18. Rapid Mapping of Lithiation Dynamics in Transition Metal Oxide Particles with Operando X-ray Absorption Spectroscopy

    Science.gov (United States)

    Nowack, Lea; Grolimund, Daniel; Samson, Vallerie; Marone, Federica; Wood, Vanessa

    2016-02-01

    Since the commercialization of lithium ion batteries (LIBs), layered transition metal oxides (LiMO2, where M = Co, Mn, Ni, or mixtures thereof) have been materials of choice for LIB cathodes. During cycling, the transition metals change their oxidation states, an effect that can be tracked by detecting energy shifts in the X-ray absorption near edge structure (XANES) spectrum. X-ray absorption spectroscopy (XAS) can therefore be used to visualize and quantify lithiation kinetics in transition metal oxide cathodes; however, in-situ measurements are often constrained by temporal resolution and X-ray dose, necessitating compromises in the electrochemistry cycling conditions used or the materials examined. We report a combined approach to reduce measurement time and X-ray exposure for operando XAS studies of lithium ion batteries. A highly discretized energy resolution coupled with advanced post-processing enables rapid yet reliable identification of the oxidation state. A full-field microscopy setup provides sub-particle resolution over a large area of battery electrode, enabling the oxidation state within many transition metal oxide particles to be tracked simultaneously. Here, we apply this approach to gain insights into the lithiation kinetics of a commercial, mixed-metal oxide cathode material, nickel cobalt aluminium oxide (NCA), during (dis)charge and its degradation during overcharge.

  19. Pt and Ru X-ray absorption spectroscopy of PtRu anode catalysts in operating direct methanol fuel cells.

    Science.gov (United States)

    Stoupin, Stanislav; Chung, Eun-Hyuk; Chattopadhyay, Soma; Segre, Carlo U; Smotkin, Eugene S

    2006-05-25

    In situ X-ray absorption spectroscopy, ex situ X-ray fluorescence, and X-ray powder diffraction enabled detailed core analysis of phase segregated nanostructured PtRu anode catalysts in an operating direct methanol fuel cell (DMFC). No change in the core structures of the phase segregated catalyst was observed as the potential traversed the current onset potential of the DMFC. The methodology was exemplified using a Johnson Matthey unsupported PtRu (1:1) anode catalyst incorporated into a DMFC membrane electrode assembly. During DMFC operation the catalyst is essentially metallic with half of the Ru incorporated into a face-centered cubic (FCC) Pt alloy lattice and the remaining half in an amorphous phase. The extended X-ray absorption fine structure (EXAFS) analysis suggests that the FCC lattice is not fully disordered. The EXAFS indicates that the Ru-O bond lengths were significantly shorter than those reported for Ru-O of ruthenium oxides, suggesting that the phases in which the Ru resides in the catalysts are not similar to oxides.

  20. X-ray absorption spectroscopy of GeO2 glass to 64 GPa

    International Nuclear Information System (INIS)

    Hong, Xinguo; Newville, Matthew; Sutton, Stephen R; Rivers, Mark L; Duffy, Thomas S

    2014-01-01

    The structural behavior of GeO 2 glass has been investigated up to 64 GPa using results from x-ray absorption spectroscopy in a diamond anvil cell combined with previously reported density measurements. The difference between the nearest Ge–O distances of glassy and rutile-type GeO 2 disappears at the Ge–O distance maximum at 20 GPa, indicating completion of the tetrahedral–octahedral transition in GeO 2 glass. The mean-square displacement σ 2 of the Ge–O distance in the first Ge–O shell increases progressively to a maximum at 10 GPa, followed by a substantial reduction at higher pressures. The octahedral glass is, as expected, less dense and has a higher compressibility than the corresponding crystalline phase, but the differences in Ge–O distance and density between the glass and the crystals are gradually eliminated over the 20–40 GPa pressure range. Above 40 GPa, GeO 2 forms a dense octahedral glass with a compressibility similar to that of the corresponding crystalline phase (α-PbO 2 type). The EXAFS and XANES spectra show evidence for subtle changes in the dense glass continuing to occur at these high pressures. The Ge–O bond distance shows little change between 45–64 GPa, and this may reflect a balance between bond shortening and a gradual coordination number increase with compression. The density of the glass is similar to that of the α–PbO 2 -type phase, but the Ge–O distance is longer and is close to that in the higher-coordination pyrite-type phase which is stable above ∼60 GPa. The density data provide evidence for a possible discontinuity and change in compressibility at 40–45 GPa, but there are no major changes in the corresponding EXAFS spectra. A pyrite-type local structural model for the glass can provide a reasonable fitting to the XAFS spectra at 64 GPa. (paper)

  1. X-Ray Absorption Spectroscopy of Fe-Substituted Allophane and Imogolite

    Science.gov (United States)

    Baker, L. L.; Strawn, D. G.; Nickerson, R. D.; McDaniel, P.

    2011-12-01

    Martian rocks and sediments contain weathering products including clay minerals formed as a result of interaction between rocks and water, and these materials can act as important indicators of past surface conditions on Mars. Weathering of terrestrial volcanic rocks similar to those on Mars produces nano-sized, variably hydrated aluminosilicate and iron oxide minerals, including allophane, imogolite, halloysite, hisingerite, and ferrihydrite. The nanoaluminosilicates can contain isomorphically substituted Fe, which may affect their spectral and physical properties as well as their eventual recrystallization products. Detection and quantification of such minerals in natural environments on Earth is difficult due to their variable chemical composition and lack of long-range crystalline order. Their accurate detection and quantification on Mars requires a better understanding of how composition affects their spectral properties and evolution to more crystalline phases. Aluminosilicate nanoparticles of varying composition were synthesized with isomorphically substituted Fe at Fe:Al ratios of 1:100. Allophanes were synthesized with Al:Si ratios of 2:1, 1:1, and 1:3. The substituted Fe was probed using Fe K-edge X-ray absorption fine structure spectroscopy (XAFS). The XAFS spectrum contains information about the molecular environment surrounding the target atom, and is an ideal technique for studying poorly crystalline materials that are difficult to characterize using bulk methods such as XRD. The near-edge (XANES) and extended (EXAFS) portions of the XAFS spectrum were examined, and allophane backscattering paths were fit using coordinates for a modified nanoball model (1). XANES spectra rule out ferrihydrite in the synthetic samples, suggesting all Fe was incorporated into the aluminosilicate structure. The XAFS results suggest that Fe substituted into the allophane structure is present as Fe(III) in octahedral coordination in a well-ordered sheet. Some Fe

  2. X-ray absorption spectroscopy on high-temperature superconductors and related compounds

    International Nuclear Information System (INIS)

    Pellegrin, E.J.H.A.

    1995-07-01

    The electronic structure of the cuprate high-temperature superconductors La 2-x Sr x CuO 4+δ , Tl 2 Ba 2 CaCu 2 O 8 and Tl 2 Ba 2 Ca 2 Cu 3 O 10 has been investigated using polarization-dependent near-edge X-ray absorption fine structure spectroscopy (NEXAFS). In addition, La 2-x Sr x NiO 4+δ has been included in the actual study as an isostructural analogue to the La 2-x Sr x CuO 4+δ system. It appears that the electronic structure of these compounds corresponds to that of a p-type doped charge-transfer insulator including electron-electron interactions on the Cu(Ni) sites and a strong hybridization between Cu(Ni) and O atoms. It is concluded that the low-energy excitations in these compounds can be described on the basis of an effective one-band Mott-Hubbard model. The polarization-dependence of the above spectra gives evidence for the strong in-plane character of the intrinsic and the doped holes. The small amount and the doping-dependence of the out-of-plane character of these charge carriers rule out models for a microscopic mechanism of superconductivity based on a large amount of hole states in the corresponding Apex-O2p z /Cu3d 3z 2 -r 2 orbitals. On the other hand, the reduction of this anisotropy in the overdoped compounds together with similar findings in the macroscopic properties seems to indicate a detrimental influence of non-planar orbitals on the superconducting properties. The differences in the energetic ordering and atomic character of the states close to the Fermi level between the undoped compounds La 2 CuO 4+δ , La 2 NiO 4+δ , and NiO have been determined from the NEXAFS data. It is found that these differences can be explained by the different size of the tetragonal crystal field splitting E Z compared to that of the Hund's rule interaction J H in these systems. This gives evidence for the high-spin d 8 ground state of the undoped nickelates (i.e. J H >E Z ). It is suggested that the polarons in La 2-x Sr x NiO 4+δ can be seen as non

  3. Nanocomposites of polypropylene and organophilic clay: X ray diffraction, absorption infrared spectroscopy with fourier transform and water vapor permeation

    International Nuclear Information System (INIS)

    Morelli, Fernanda C.; Ruvolo Filho, Adhemar

    2010-01-01

    In this work nano composites were prepared from polypropylene, graft polypropylene with maleic anhydride as compatibilizer and organophilic montmorillonite Cloisite 20A with concentrations of 1.5, 2.5, 5.0 and 7.5% clay. The mixture was made in the melt state using a twin screw extruder. The materials were characterized by X ray diffraction, infrared spectroscopy with Fourier transform and analysis of water vapor permeation. The results of X ray diffraction and absorption infrared spectroscopy indicates the formation of nano composites with structures probably exfoliate and or intercalated for concentrations of 1.5 and 2.5% clay, and provided a marked decrease in the water permeability, corroborating with other analyses. (author)

  4. Segmented Monolithic Germanium Detector Arrays for X-ray Absorption Spectroscopy. Final Report

    International Nuclear Information System (INIS)

    Hull, Ethan L.

    2011-01-01

    The experimental results from the Phase I effort were extremely encouraging. During Phase I PHDs Co. made the first strides toward a new detector technology that could have great impact on synchrotron x-ray absorption (XAS) measurements, and x-ray detector technology in general. Detector hardware that allowed critical demonstration measurements of our technology was designed and fabricated. This new technology allows good charge collection from many pixels on a single side of a multi-element monolithic germanium planar detector. The detector technology provides 'dot-like' collection electrodes having very low capacitance. The detector technology appears to perform as anticipated in the Phase I proposal. In particular, the 7-pixel detector studied showed remarkable properties; making it an interesting example of detector physics. The technology is enabled by the use of amorphous germanium contact technology on germanium planar detectors. Because of the scalability associated with the fabrication of these technologies at PHDs Co., we anticipate being able to supply larger detector systems at significantly lower cost than systems made in the conventional manner.

  5. X-ray absorption fine structure (XAFS) spectroscopy: a tool for structural studies in material sciences (abstract)

    International Nuclear Information System (INIS)

    Akhtar, M.J.

    2011-01-01

    XAFS spectroscopy has revealed itself as a powerful technique for structural characterization of the local atomic environment of individual atomic species, including bond distances, coordination numbers and type of nearest neighbors surrounding the central atom. This technique is particularly useful for materials that show considerable structural and chemical disorder. XAFS spectroscopy has found extensive applications in determining the local atomic and electronic structure of the absorbing centers (atoms) in the materials science, physics, chemistry, biology and geophysics. X-ray absorption edges contain a variety of information on the chemical state and the local structure of the absorbing atom. On the higher energy side of an absorption edge fine structure is observed due to backscattering of the emitted photoelectron. The post-edge region can be divided into two parts. The X-ray Absorption Near Edge Structure (XANES) which extends up to 50 eV of an absorption edge, the spectrum is interpreted in terms of the appropriate components of the local density of states, which would be expected to be sensitive to the valence state of the atom. The intensity, shape and location of the absorption edge features provide information on the valence state, electronic structure and coordination geometry of the absorbing atom.The Extended X-ray Absorption Fine Structure (EXAFS) region is dominated by the single scattering processes and extends up to 1000 eV above the edge and provides information on the radial distribution (coordination number, radial distance and type of neighboring atoms) around the central atom. The results on perovskite based and spinel ferrites systems will be presented, where valence state and cation distributions are determined; the present study will show focus on SrFeO/sub 3/, MnFe/sub 2/O/sub 4/ and Zn/sub 1-x/Ni/sub x/Fe/sub 2/O/sub 4/ materials. (author)

  6. Structural anisotropy in amorphous SnO2 film probed by X-ray absorption spectroscopy

    Science.gov (United States)

    Zhu, Q.; Ma, Q.; Buchholz, D. B.; Chang, R. P. H.; Bedzyk, M. J.; Mason, T. O.

    2013-07-01

    Polarization-dependent X-ray absorption measurements reveal the existence of structural anisotropy in amorphous (a-) SnO2 film. The anisotropy is readily seen for the second neighbor interaction whose magnitude differs along three measured directions. The differences can be well accounted for by 10%-20% variation in the Debye-Waller factor. Instead of a single Gaussian distribution found in crystalline SnO2, the Sn-O bond distribution is bimodal in a-SnO2 whose separation shows a weak angular dependence. The oxygen vacancies, existing in the a-SnO2 film in the order of 1021 cm-3, distribute preferentially along the film surface direction.

  7. In situ analyses of Ag speciation in tissues of cucumber and wheat using synchrotron-based X-ray absorption spectroscopy

    Data.gov (United States)

    U.S. Environmental Protection Agency — In situ analyses of Ag speciation in tissues of cucumber and wheat using synchrotron-based X-ray absorption spectroscopy showing spectral fitting and linear...

  8. Optically detected X-ray absorption spectroscopy measurements as a means of monitoring corrosion layers on copper.

    Science.gov (United States)

    Dowsett, Mark G; Adriaens, Annemie; Jones, Gareth K C; Poolton, Nigel; Fiddy, Steven; Nikitenko, Sergé

    2008-11-15

    XANES and EXAFS information is conventionally measured in transmission through the energy-dependent absorption of X-rays or by observing X-ray fluorescence, but secondary fluorescence processes, such as the emission of electrons and optical photons (e.g., 200-1000 nm), can also be used as a carrier of the XAS signatures, providing complementary information such as improved surface specificity. Where the near-visible photons have a shorter range in a material, the data will be more surface specific. Moreover, optical radiation may escape more readily than X-rays through liquid in an environmental cell. Here, we describe a first test of optically detected X-ray absorption spectroscopy (ODXAS) for monitoring electrochemical treatments on copper-based alloys, for example, heritage metals. Artificially made corrosion products deposited on a copper substrate were analyzed in air and in a 1% (w/v) sodium sesquicarbonate solution to simulate typical conservation methods for copper-based objects recovered from marine environments. The measurements were made on stations 7.1 and 9.2 MF (SRS Daresbury, UK) using the mobile luminescence end station (MoLES), supplemented by XAS measurements taken on DUBBLE (BM26 A) at the ESRF. The ODXAS spectra usually contain fine structure similar to that of XAS spectra measured in X-ray fluorescence. Importantly, for the compounds examined, the ODXAS is significantly more surface specific, and >98% characteristic of thin surface layers of 0.5-1.5-microm thickness in cases where X-ray measurements are dominated by the substrate. However, EXAFS and XANES from broadband optical measurements are superimposed on a high background due to other optical emission modes. This produces statistical fluctuations up to double what would be expected from normal counting statistics because the data retain the absolute statistical fluctuation in the original raw count, while losing up to 70% of their magnitude when background is removed. The problem may be

  9. Applications of X-ray absorption spectroscopy and low temperature XMCD to metalloproteins

    Energy Technology Data Exchange (ETDEWEB)

    Christiansen, J.H. [Univ. of California, Davis, CA (United States). Dept. of Applied Science]|[Lawrence Berkeley National Lab., CA (United States). Energy and Environment Div.

    1996-01-01

    The author has used the extended X-ray absorption fine structure (EXAFS) and ultra-low temperature X-ray magnetic circular dichroism (XMCD) to study the environments of the metal sites in metalloproteins. EXAFS has been used to study the Zn site in spinach carbonic anhydrase. The EXAFS, in parallel with site directed mutagenesis studies, indicate that the active site Zn is in a cys-cys-his-H{sub 2}O environment, very different from the mammalian carbonic anhydrase active site. Nitrogenase, the primary enzyme in biological nitrogen fixation, contains two complex metal clusters of unique structure. EXAFS studies at the Fe and Mo K-edges of nitrogenase solutions and crystals yielded information about the various metal-metal distances in these two clusters. The author assigned 4 Fe and 3 Mo interactions >4 {angstrom}. Single crystal Mo K-edge EXAFS then found a very long Fe-Fe distance of {approximately}5.1 {angstrom}. These distances were then used to further refine the proposed crystallographic models to their highest accuracy yet. Studies were carried further by examining nitrogenas in oxidized and reduced forms--states for which there is no crystallographic information. Small structural changes were observed and an EXAFS model was put forth that attempts to deconvolute the EXAFS distances of the two metal clusters. Nitrogenase Apo I, a genetic mutant of nitrogenase which is though to contain only one of the two different metal clusters, was also examined using EXAFS. These studies showed results consistent with current models, yet the metal clusters were very disordered. Finally, ultra-low temperature methods were used to further the development of XMCD as a technique for studying biological systems. Experiments were performed on the copper in plastocyanin. Data was collected that definitively proves that the sample surface was at 0.55 {+-} 0.05 K. This result opens the door to further study of more complex biological metal clusters.

  10. Anionic and cationic redox and interfaces in batteries: Advances from soft X-ray absorption spectroscopy to resonant inelastic scattering

    Science.gov (United States)

    Yang, Wanli; Devereaux, Thomas P.

    2018-06-01

    Recent advances in battery science and technology have triggered both the challenges and opportunities on studying the materials and interfaces in batteries. Here, we review the recent demonstrations of soft X-ray spectroscopy for studying the interfaces and electrode materials. The focus of this review is on the recently developed mapping of resonant inelastic X-ray scattering (mRIXS) as a powerful probe of battery chemistry with superior sensitivity. Six different channels of soft X-ray absorption spectroscopy (sXAS) are introduced for different experimental purposes. Although conventional sXAS channels remain effective tools for quantitative analysis of the transition-metal states and surface chemistry, we elaborate the limitations of sXAS in both cationic and anionic redox studies. Particularly, based on experimental findings in various electrodes, we show that sXAS is unreliable for studying oxygen redox. We then demonstrate the mRIXS as a reliable technique for fingerprinting oxygen redox and summarize several crucial observations. We conclude that mRIXS is the tool-of-choice to study both the practical issue on reversibility of oxygen redox and the fundamental nature of bulk oxygen states. We hope this review clarifies the popular misunderstanding on oxygen sXAS results of oxide electrodes, and establishes a reliable technique for detecting oxygen redox through mRIXS.

  11. Ligand-field symmetry effects in Fe(ii) polypyridyl compounds probed by transient X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Cho, Hana; Strader, Matthew L.; Hong, Kiryong; Jamula, Lindsey; Gullikson, Eric M.; Kim, Tae Kyu; de Groot, Frank M. F.; McCusker, James K.; Schoenlein, Robert W.; Huse, Nils

    2012-01-01

    Ultrafast excited-state evolution in polypyridyl FeII complexes are of fundamental interest for understanding the origins of the sub-ps spin-state changes that occur upon photoexcitation of this class of compounds as well as for the potential impact such ultrafast dynamics have on incorporation of these compounds in solar energy conversion schemes or switchable optical storage technologies. We have demonstrated that ground-state and, more importantly, ultrafast time-resolved x-ray absorption methods can offer unique insights into the interplay between electronic and geometric structure that underpin the photo-induced dynamics of this class of compounds. The present contribution examines in greater detail how the symmetry of the ligand field surrounding the metal ion can be probed using these x-ray techniques. In particular, we show that steady-state K-edge spectroscopy of the nearest-neighbour nitrogen atoms reveals the characteristic chemical environment of the respective ligands and suggests an interesting target for future charge-transfer femtosecond and attosecond spectroscopy in the x-ray water window.

  12. Time resolved measurement of laser-ablated particles by LAPXAS (Laser Plasma Soft X-ray Absorption Spectroscopy)

    International Nuclear Information System (INIS)

    Miyashita, Atsumi; Yoda, Osamu; Murakami, Kouichi

    1999-01-01

    The time- and spatially-resolved properties of laser ablated carbon, boron and silicon particles were measured by LAPXAS (Laser Plasma Soft X-ray Absorption Spectroscopy). The maximum speed of positively charged ions is higher than those of neutral atoms and negatively charged ions. The spatial distributions of the laser-ablated particles in the localized rare gas environment were measured. In helium gas environment, by the helium cloud generated on the top of ablation plume depressed the ablation plume. There is no formation of silicon clusters till 15 μs after laser ablation in the argon gas environment. (author)

  13. Electronic Structure from Iron L-edge Spectroscopy : An Example of Spin Transition Evidenced by Soft X-ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Cartier dit Moulin, Ch.; Flank, A.M.; Rudolf, P.; Chen, C.T.

    1993-01-01

    Soft X-ray Absorption Spectroscopy at the transition metal L2,3 edges provides information about the 3d unoccupied states by dipole allowed transitions. We have recorded iron L2,3 edges in order to follow the reversible thermal spin interconversion (S=2 S=0) of the Fe(II)(o-phenantroline)2(NCS)2.

  14. A study of the Nb3Ge system by Ge K-edge extended x-ray absorption fine structure and x-ray absorption near-edge structure spectroscopy

    International Nuclear Information System (INIS)

    Saini, N L; Filippi, M; Wu Ziyu; Oyanagi, H; Ihara, H; Iyo, A; Agrestini, S; Bianconi, A

    2002-01-01

    The local structure of Nb 3 Ge intermetallic superconductor has been studied by Ge K-edge absorption spectroscopy. Extended x-ray absorption fine structure (EXAFS) experiments show two Ge-Nb distances. In addition to the crystallographic distance of ∼2.87 A, there exists a second Ge-Nb distance, shorter than the first by ∼0.2 A, assigned to a phase with short-range symmetry related to local displacements in the Nb-Nb chains. The x-ray absorption near-edge structure (XANES) spectrum has been simulated by full multiple-scattering calculations considering the local displacements determined by the EXAFS analysis. The XANES spectrum has been well reproduced by considering a cluster of 99 atoms within a radius of about 7 A from the central Ge atom and introducing determined local displacements

  15. Probing the influence of X-rays on aqueous copper solutions using time-resolved in situ combined video/X-ray absorption near-edge/ultraviolet-visible spectroscopy

    NARCIS (Netherlands)

    Mesu, J. Gerbrand; Beale, Andrew M.; de Groot, Frank M. F.; Weckhuysen, Bert M.

    2006-01-01

    Time-resolved in situ video monitoring and ultraviolet-visible spectroscopy in combination with X-ray absorption near-edge spectroscopy (XANES) have been used for the first time in a combined manner to study the effect of synchrotron radiation on a series of homogeneous aqueous copper solutions in a

  16. Experimental and theoretical study of electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Festa, Floriane

    2013-01-01

    Matter in extreme conditions belongs to Warm Dense Matter regime which lays between dense plasma regime and condensed matter. This regime is still not well known, indeed it is very complex to generate such plasma in the laboratory to get experimental data and validate models. The goal of this thesis is to study electronic structure of aluminum in extreme conditions with X-ray absorption spectroscopy. Experimentally aluminum has reached high densities and high temperatures, up to now unexplored. An X-ray source has also been generated to probe highly compressed aluminum. Two spectrometers have recorded aluminum absorption spectra and aluminum density and temperature conditions have been deduced thanks to optical diagnostics. Experimental spectra have been compared to ab initio spectra, calculated in the same conditions. The theoretical goal was to validate the calculation method in high densities and high temperatures regime with the study of K-edge absorption modifications. We also used absorption spectra to study the metal-non metal transition which takes place at low density (density ≤ solid density). This transition could be study with electronic structure modifications of the system. (author) [fr

  17. Orientation of One-Dimensional Silicon Polymer Films Studied by X-Ray Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Md. Abdul Mannan

    2012-01-01

    Full Text Available Molecular orientations for thin films of one-dimensional silicon polymers grown by vacuum evaporation have been assigned by near-edge X-ray absorption fine structure (NEXAFS using linearly polarized synchrotron radiation. The polymer investigated was polydimethylsilane (PDMS which is the simplest stable silicon polymer, and one of the candidate materials for one-dimensional molecular wire. For PDMS films deposited on highly oriented pyrolytic graphite (HOPG, four resonance peaks have been identified in the Si K-edge NEXAFS spectra. Among these peaks, the intensities of the two peaks lower-energy at 1842.0 eV and 1843.2 eV were found to be strongly polarization dependent. The peaks are assigned to the resonance excitations from the Si 1s to σ∗ pyz and σ∗ px orbitals localized at the Si–C and Si–Si bonds, respectively. Quantitative evaluation of the polarization dependence of the NEXAFS spectra revealed that the molecules are self-assembled on HOPG surface, and the backbones of the PDMS are oriented nearly parallel to the surface. The observed orientation is opposite to the previously observed results for PDMS on the other surfaces such as oxide (indium tin oxide and metal (polycrystalline copper. The flat-lying feature of PDMS observed only on HOPG surface is attributed to the interaction between CH bonds in PDMS and π orbitals in HOPG surface.

  18. Surface modification study of borate materials from B K-edge X-ray absorption spectroscopy

    Science.gov (United States)

    Kasrai, Masoud; Fleet, Michael E.; Muthupari, Swaminathan; Li, D.; Bancroft, G. M.

    The B K-edge X-ray absorption near-edge structure (XANES) spectra of two borates with tetrahedrally-coordinated B [[4]B; natural danburite (CaB2Si2O8) and synthetic boron phosphate (BPO4)] have been recorded in total electron yield (TEY) and fluorescence yield (FY) modes to investigate the surface and bulk structure of these materials. The TEY XANES measurement shows that danburite is susceptible to surface damage involving conversion of [4]B sites to [3]B sites by reaction with moisture and/or mechanical abrasion (grinding, polishing, etc.). The bulk of the mineral is essentially unaffected. Commercial boron phosphate powder exhibits more extensive surface and bulk damage, which increases with air exposure but is recovered on heating at 650°C. In contrast to ELNES, the XANES technique is not affected by beam damage and when collected in the FY mode is capable of yielding meaningful information on the coordination and intermediate-range structure of B in borate and borosilicate materials.

  19. Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy: Annual progress report

    International Nuclear Information System (INIS)

    Sayers, D.E.

    1986-01-01

    Although only in operation since May, 1985, the X-11 participation research team (PRT) at the NSLS has already demonstrated that it is one of the leading centers of x-ray absorption spectroscopy (XAS). During this time, results have been obtained and programs initiated in a number of areas, for example: interfaces, including deposited metal-metal and metal-semiconductor systems, multilayers and ion implanted layers; electrochemical systems, including Pt electrode fuel cells, Ni oxide battery electrodes, conducting polymers, passivation and corrosion; catalysts, including highly-dispersed supported metal catalysts and zeolite systems; quasi-crystals, heavy fermion systems, uranium and neptunium compounds, rare gas clusters, disordered metals and semiconductors, ferroelectric transition; and, biological systems and related models, including synthetic porphyrins and a number of metalloproteins. In concert with these scientific results have been a number of developments involving the technique itself. These include implementation of unique optical systems on both the A and B lines for optical performance over their designed energy ranges, advances in experimental capability, particular in glancing angle studies, optimization of ion chambers for surface studies, the improvement of electron yield detectors, and improved software for data acquisition and analysis. This report emphasizes some of the research highlights and significant developments of our PRT which occurred during the past year. A detailed bibliography of papers and talks resulting from work done at our beamline and the progress reports for our PRT which were in the 1985 NSLS Annual Report are appended

  20. 1913–2013 – The centennial of X-ray absorption spectroscopy (XAS): Evidences about a question still open

    Energy Technology Data Exchange (ETDEWEB)

    Mottana, Annibale, E-mail: annibale.mottana@uniroma3.it [Università degli Studi Roma Tre, Dipartimento di Scienze, Largo S. Leonardo Murialdo 1, I-00146 Roma (Italy); Istituto Nazionale di Fisica Nucleare, Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati, RM (Italy)

    2014-10-15

    Highlights: • X-ray Absorption Spectroscopy (XAS) cannot be dated exactly as for its birth. • The assumed discoverer, M. de Broglie, was preceded by J. Herweg in the submission. • However, both their spectra were found to be mistaken. • Before the work of W. Stenström and H. Fricke no sure evidence of XAS is published. • The solution is, probably, taking October 1, 1918 as XAS fictitious birthday. - Abstract: In 1913 J. Herweg first (June 30) and M. de Broglie slightly later (November 17) claimed the discovery of a series of spots and lines closely following the main absorption edges of heavy metals, which they interpreted as the proof of the existence of X-ray spectra analogous to light spectra. In the following year they documented their discoveries via photographic plates. However, they were both discredited: Herweg by G.E.M. Jauncey, who showed that his spectra, taken on Pt and W, did not obey Moseley's rule; de Broglie by W.H. Bragg, M. Siegbahn and E. Wagner, who showed that his lines were in fact the fluorescence lines of the Ag and Br constituents of the photographic emulsion. Consequently, W. Stenström's description (sent to publisher on July 2, 1918) of certain photographically recorded and graphically rendered modulations near the M-series edges of heavy metals may possibly be the first published evidence of true X-ray absorption spectra. Indeed, they were interpreted as such by W. Kossel (1920) in his seminal theoretical paper. Otherwise, H. Fricke's table, although printed in 1920, which exhibits the photographic plate of sulphur absorption dated October 1, 1918, and its graphical rendering by a photometric method, is the first unequivocally dated evidence of recorded modulations at a XAS K-edge.

  1. Study of Cr(VI) adsorption onto magnetite nanoparticles using synchrotron-based X-ray absorption spectroscopy

    Science.gov (United States)

    Chen, Yen-Hua; Liu, Dian-Yu; Lee, Jyh-Fu

    2018-04-01

    In this study, the efficiency of Cr(VI) adsorption onto nano-magnetite was examined by batch experiments, and the Cr(VI) adsorption mechanism was investigated using synchrotron-based X-ray absorption spectroscopy. Magnetite nanoparticles with a mean diameter of 10 nm were synthesized using an inexpensive and simple co-precipitation method. It shows a saturation magnetization of 54.3 emu/g, which can be recovered with an external magnetic field. The adsorption data fitted the Langmuir adsorption isotherm well, implying a monolayer adsorption behavior of Cr(VI) onto nano-magnetite. X-ray absorption spectroscopy results indicate that the adsorption mechanism involves electron transfer between Fe(II) in nano-magnetite (Fe2+OFe3+ 2O3) and Cr(VI) to transform into Cr(III), which may exist as an Fe(III)-Cr(III) mixed solid phase. Moreover, the Cr(III)/Cr(VI) ratio in the final products can be determined by the characteristic pre-edge peak area of Cr(VI) in the Cr K-edge spectrum. These findings suggest that nano-magnetite is effective for Cr(VI) removal from wastewater because it can transform highly poisonous Cr(VI) species into nontoxic Cr(III) compounds, which are highly insoluble and immobile under environmental conditions.

  2. Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy: Annual progress report

    International Nuclear Information System (INIS)

    Sayers, D.E.

    1987-01-01

    The research programs reported span virtually the entire range of condensed matter studies involving the fields of solid state physics, chemistry, electrochemistry, materials science and biochemistry. Results are discussed for various groups. Topics reported include work on amorphous chalcogenide semiconductors, particularly photostructural changes, kinetics of structural changes and rapid quenching, bond strengths, force constants and phonons. Also reported are temperature dependent EXAFS studies of bonding in high temperature alloys, amorphous systems, disordered alloys and studies of resolve electronic structure, EXAFS and XANES studies of permanent magnet systems based on Nd 2 Fe 14 B, glancing angle EXAFS study of Nb/Al and Nb/Si interfacial systems, x-ray absorption of krypton-implanted solids and high dose implants into silicon, and x-ray absorption and EXAFS studies of superconducting oxide compounds of Cu and related magnetic systems. Work is also reported on XAFS measurements on the icosahedral phase

  3. Urban airborne lead: X-ray absorption spectroscopy establishes soil as dominant source.

    Directory of Open Access Journals (Sweden)

    Nicholas E Pingitore

    Full Text Available BACKGROUND: Despite the dramatic decrease in airborne lead over the past three decades, there are calls for regulatory limits on this potent pediatric neurotoxin lower even than the new (2008 US Environmental Protection Agency standard. To achieve further decreases in airborne lead, what sources would need to be decreased and what costs would ensue? Our aim was to identify and, if possible, quantify the major species (compounds of lead in recent ambient airborne particulate matter collected in El Paso, TX, USA. METHODOLOGY/PRINCIPAL FINDINGS: We used synchrotron-based XAFS (x-ray absorption fine structure to identify and quantify the major Pb species. XAFS provides molecular-level structural information about a specific element in a bulk sample. Pb-humate is the dominant form of lead in contemporary El Paso air. Pb-humate is a stable, sorbed complex produced exclusively in the humus fraction of Pb-contaminated soils; it also is the major lead species in El Paso soils. Thus such soil must be the dominant source, and its resuspension into the air, the transfer process, providing lead particles to the local air. CONCLUSIONS/SIGNIFICANCE: Current industrial and commercial activity apparently is not a major source of airborne lead in El Paso, and presumably other locales that have eliminated such traditional sources as leaded gasoline. Instead, local contaminated soil, legacy of earlier anthropogenic Pb releases, serves as a long-term reservoir that gradually leaks particulate lead to the atmosphere. Given the difficulty and expense of large-scale soil remediation or removal, fugitive soil likely constrains a lower limit for airborne lead levels in many urban settings.

  4. X-ray Absorption Spectroscopy Identifies Calcium-Uranyl-Carbonate Complexes at Environmental Concentrations

    International Nuclear Information System (INIS)

    Kelly, Shelly D.; Kemner, Kenneth M.; Brooks, Scott C.

    2007-01-01

    Current research on bioremediation of uranium-contaminated groundwater focuses on supplying indigenous metal-reducing bacteria with the appropriate metabolic requirements to induce microbiological reduction of soluble uranium(VI) to poorly soluble uranium(IV). Recent studies of uranium(VI) bioreduction in the presence of environmentally relevant levels of calcium revealed limited and slowed uranium(VI) reduction and the formation of a Ca-UO2-CO3 complex. However, the stoichiometry of the complex is poorly defined and may be complicated by the presence of a Na-UO2-CO3 complex. Such a complex might exist even at high calcium concentrations, as some UO2-CO3 complexes will still be present. The number of calcium and/or sodium atoms coordinated to a uranyl carbonate complex will determine the net charge of the complex. Such a change in aqueous speciation of uranium(VI) in calcareous groundwater may affect the fate and transport properties of uranium. In this paper, we present the results from X-ray absorption fine structure (XAFS) measurements of a series of solutions containing 50 lM uranium(VI) and 30 mM sodium bicarbonate, with various calcium concentrations of 0-5 mM. Use of the data series reduces the uncertainty in the number of calcium atoms bound to the UO2-CO3 complex to approximately 0.6 and enables spectroscopic identification of the Na-UO2-CO3 complex. At nearly neutral pH values, the numbers of sodium and calcium atoms bound to the uranyl triscarbonate species are found to depend on the calcium concentration, as predicted by speciation calculations

  5. Urban airborne lead: X-ray absorption spectroscopy establishes soil as dominant source.

    Science.gov (United States)

    Pingitore, Nicholas E; Clague, Juan W; Amaya, Maria A; Maciejewska, Beata; Reynoso, Jesús J

    2009-01-01

    Despite the dramatic decrease in airborne lead over the past three decades, there are calls for regulatory limits on this potent pediatric neurotoxin lower even than the new (2008) US Environmental Protection Agency standard. To achieve further decreases in airborne lead, what sources would need to be decreased and what costs would ensue? Our aim was to identify and, if possible, quantify the major species (compounds) of lead in recent ambient airborne particulate matter collected in El Paso, TX, USA. We used synchrotron-based XAFS (x-ray absorption fine structure) to identify and quantify the major Pb species. XAFS provides molecular-level structural information about a specific element in a bulk sample. Pb-humate is the dominant form of lead in contemporary El Paso air. Pb-humate is a stable, sorbed complex produced exclusively in the humus fraction of Pb-contaminated soils; it also is the major lead species in El Paso soils. Thus such soil must be the dominant source, and its resuspension into the air, the transfer process, providing lead particles to the local air. Current industrial and commercial activity apparently is not a major source of airborne lead in El Paso, and presumably other locales that have eliminated such traditional sources as leaded gasoline. Instead, local contaminated soil, legacy of earlier anthropogenic Pb releases, serves as a long-term reservoir that gradually leaks particulate lead to the atmosphere. Given the difficulty and expense of large-scale soil remediation or removal, fugitive soil likely constrains a lower limit for airborne lead levels in many urban settings.

  6. Local versus global electronic properties of chalcopyrite alloys: X-ray absorption spectroscopy and ab initio calculations

    Energy Technology Data Exchange (ETDEWEB)

    Sarmiento-Pérez, Rafael; Botti, Silvana, E-mail: silvana.botti@univ-lyon1.fr [Institut Lumière Matière and ETSF, UMR5306 Université Lyon 1-CNRS, Université de Lyon, F-69622 Villeurbanne Cedex (France); Schnohr, Claudia S., E-mail: c.schnohr@uni-jena.de [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Lauermann, Iver [Helmholtz-Zentrum Berlin für Materialien und Energie, Hahn-Meitner Platz 1, 14109 Berlin (Germany); Rubio, Angel [Nano-Bio Spectroscopy Group and ETSF Scientific Development Centre, Departamento de Física de Materiales, Centro de Física de Materiales CSIC-MPC and DIPC, Universidad del País Vasco UPV/EHU, Avenida de Tolosa 72, E-20018 San Sebastián (Spain); Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany); Johnson, Benjamin, E-mail: benjamin.johnson@alumni.tu-berlin.de [Fritz Haber Institute, Max Planck Society, Faradayweg 4-6, 14195 Berlin (Germany)

    2014-09-07

    Element-specific unoccupied electronic states of Cu(In, Ga)S{sub 2} were studied as a function of the In/Ga ratio by combining X-ray absorption spectroscopy with density functional theory calculations. The S absorption edge shifts with changing In/Ga ratio as expected from the variation of the band gap. In contrast, the cation edge positions are largely independent of composition despite the changing band gap. This unexpected behavior is well reproduced by our calculations and originates from the dependence of the electronic states on the local atomic environment. The changing band gap arises from a changing spatial average of these localized states with changing alloy composition.

  7. X-ray absorption spectroscopy and high-energy XRD study of the local environment of copper in antibacterial copper-releasing degradable phosphate glasses

    OpenAIRE

    Pickup, David M.; Ahmed, Ifty; Fitzgerald, Victoria; Moss, Rob M.; Wetherall, Karen; Knowles, Jonathan C.; Smith, Mark E.; Newport, Robert J.

    2006-01-01

    Phosphate-based glasses of the general formula Na2O-CaO-P2O5 are degradable in an aqueous environment, and therefore can act as antibacterial materials through the inclusion of ions such as copper. In this study, CuO and Cu2O were added to Na2O-CaO-P2O5 glasses (1-20 mol% Cu) and X-ray absorption spectroscopy (XAS) and high-energy X-ray diffraction (HEXRD) used to probe the local environment of the copper ions. Copper K-edge X-ray absorption near-edge structure (XANES) spectra confirm the oxi...

  8. Enabling liquid solvent structure analysis using hard x-ray absorption spectroscopy with a transferrable microfluidic reactor

    Science.gov (United States)

    Zheng, Jian; Zhang, Wei; Wang, Feng; Yu, Xiao-Ying

    2018-05-01

    In this paper, a vacuum compatible microfluidic device, system for analysis at the liquid vacuum interface, is integrated to hard x-ray absorption spectroscopy to obtain the local structure of K3[Fe(CN)6] in aqueous solutions with three concentrations of 0.5 M, 0.05 M, and 0.005 M. The solutions were sealed in a microchannel 500 µm wide and 300 µm deep in a portable microfluidic device. The Fe K-edge x-ray absorption spectra indicate a presence of Fe(III) in the complex in water, with an octahedral geometry coordinated with 6 C atoms in the first shell with a distance of ~1.92 Å and 6 N atoms in the second shell with a distance of ~3.10 Å. Varying the concentration has no observable influence on the structure of K3[Fe(CN)6]. Our results demonstrate the feasibility of using microfluidic based liquid cells in large synchrotron facilities. Using portable microfludic reactors provides a viable approach to enable multifaceted measurements of liquids in the future.

  9. Enabling liquid solvent structure analysis using hard x-ray absorption spectroscopy with a transferrable microfluidic reactor

    Energy Technology Data Exchange (ETDEWEB)

    Zheng, Jian; Zhang, Wei; Wang, Feng; Yu, Xiao-Ying

    2018-04-11

    In this paper, a vacuum compatible microfluidic device, System for Analysis at the Liquid Vacuum Interface (SALVI), is integrated to hard x-ray absorption spectroscopy (XAS) to obtain the local structure of K3[Fe(CN)6] in aqueous solutions with three concentrations of 0.5 M, 0.05 M, and 0.005 M. The solutions were sealed in a microchannel of 500 μm wide and 300 µm deep in a portable microfluidic device. The Fe K-edge x-ray absorption spectra show that the complex in water is Fe(III). The complex is present with octahedral geometry coordinated with 6 C atoms in the first shell with a distance of ~1.92 Å and 6 N atoms in the second shell with a distance of ~3.10 Å. Varying the concentration has no observable influence on the structure of K3[Fe(CN)6]. Our results demonstrate the feasibility of using microfluidic based liquid cells in large synchrotron facilities and it is a viable approach to enable multifaceted measurements of liquids in the future.

  10. In operando observation system for electrochemical reaction by soft X-ray absorption spectroscopy with potential modulation method

    International Nuclear Information System (INIS)

    Nagasaka, Masanari; Kosugi, Nobuhiro; Yuzawa, Hayato; Horigome, Toshio

    2014-01-01

    In order to investigate local structures of electrolytes in electrochemical reactions under the same scan rate as a typical value 100 mV/s in cyclic voltammetry (CV), we have developed an in operando observation system for electrochemical reactions by soft X-ray absorption spectroscopy (XAS) with a potential modulation method. XAS spectra of electrolytes are measured by using a transmission-type liquid flow cell with built-in electrodes. The electrode potential is swept with a scan rate of 100 mV/s at a fixed photon energy, and soft X-ray absorption coefficients at different potentials are measured at the same time. By repeating the potential modulation at each fixed photon energy, it is possible to measure XAS of electrochemical reaction at the same scan rate as in CV. We have demonstrated successful measurement of the Fe L-edge XAS spectra of aqueous iron sulfate solutions and of the change in valence of Fe ions at different potentials in the Fe redox reaction. The mechanism of these Fe redox processes is discussed by correlating the XAS results with those at different scan rates

  11. Monopeptide versus Monopeptoid: Insights on Structure and Hydration of Aqueous Alanine and Sarcosine via X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; England, Alice; Prendergast, David; Saykally, Richard J.

    2009-11-19

    Despite the obvious significance, the aqueous interactions of peptides remain incompletely understood. Their synthetic analogues called peptoids (poly-N-substituted glycines), have recently emerged as a promising biomimetic material, particularly due to their robust secondary structure and resistance to denaturation. We describe comparative near-edge x-ray absorption fine structure (NEXAFS) spectroscopy studies of aqueous sarcosine, the simplest peptoid, and alanine, its peptide isomer, interpreted by density functional theory calculations. The sarcosine nitrogen K-edge spectrum is blue-shifted with respect to that of alanine, in agreement with our calculations; we conclude that this shift results primarily from the methyl group substitution on the nitrogen of sarcosine. Our calculations indicate that the nitrogen K-edge spectrum of alanine differs significantly between dehydrated and hydrated scenarios, while that of the sarcosine zwitterion is less affected by hydration. In contrast, the computed sarcosine spectrum is greatly impacted by conformational variations, while the alanine spectrum is not. This relates to a predicted solvent dependence for alanine, as compared to sarcosine. Additionally, we show the theoretical nitrogen K-edge spectra to be sensitive to the degree of hydration, indicating that experimental X-ray spectroscopy may be able to distinguish between bulk and partial hydration, such as found in confined environments near proteins and in reverse micelles.

  12. Magnetic and structural properties of Fe/Pd multilayers studied by magnetic x-ray dichroism and x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Mini, S.M.; Fullerton, E.E.; Sowers, C.H.; Fontaine, A.; Pizzini, S.; Bommannavar, A.S.; Traverse, A.; Baudelet, F.

    1994-12-01

    The results of magnetic circular x-ray dichroism (MCXD) measurements and extended x-ray absorption fine structure measurements (EXAFS) of the Fe K-edges of textured Fe(110)/Pd(111) multilayers are reported. The EXAFS results indicates that the iron in the system goes from bcc to a more densely packed system as the thickness of the iron layer is decreased. The magnetic properties were measured by SQUID magnetometry from 5-350 K. For all the samples, the saturation magnetization was significantly enhanced over the bulk values indicating the interface Pd atoms are polarized by the Fe layer. The enhancement corresponds to a moment of ∼2.5μ B per interface Pd atom

  13. 100 years of X-rays, 20 years of absorption spectroscopy with the synchrotron radiation: history, principles and a few examples of applications

    International Nuclear Information System (INIS)

    Michalowicz, A.; Moscovici, J.; Mimouni, A.

    1995-01-01

    The centenary of the discovery of X-rays is the occasion to summarize the history of X-ray absorption spectroscopy (XAS) and its development on synchrotron radiation sources, to give the underlying principles and to illustrate the possible uses of this spectroscopy by three examples: (a) the structural characterization of disordered spin transition coordination compounds by EXAFS spectroscopy; (b) the ligand binding to vitamin B 12 by XANES spectroscopy; and (c) the chemical analysis of sulfur compounds included in fly-ashes by low-energy XANES spectroscopy. (authors). 23 refs., 8 figs

  14. X-ray absorption spectroscopy on the calcium cofactor to the manganese cluster in photosynthetic oxygen evolution

    Energy Technology Data Exchange (ETDEWEB)

    Cinco, Roehl M. [Univ. of California, Berkeley, CA (United States)

    1999-12-01

    Along with Mn, calcium and chloride ions are necessary cofactors for oxygen evolution in Photosystem II (PS II). To further test and verify whether Ca is close to the Mn cluster, the authors substituted strontium for Ca and probed from the Sr point of view for any nearby Mn. The extended X-ray absorption fine structure (EXAFS) of Sr-reactivated PS II indicates major differences between the intact and NH2OH-treated samples. In intact samples, the Fourier transform of the Sr EXAFS shows a Fourier peak that is missing in inactive samples. This peak II is best simulated by two Mn neighbors at a distance of 3.5 Angstrom, confirming the proximity of Ca (Sr) cofactor to the Mn cluster. In addition, polarized Sr EXAFS on oriented Sr-reactivated samples shows this peak II is dichroic: large magnitude at 10 degrees (angle between the PS II membrane normal and the x-ray electric field vector) and small at 80 degrees. Analysis of the dichroism yields the relative angle between the Sr-Mn vector and membrane normal (23 degrees ± 4 degrees), and the isotropic coordination number for these layered samples. X-ray absorption spectroscopy has also been employed to assess the degree of similarity between the manganese cluster in PS II and a family of synthetic manganese complexes containing the distorted cubane [Mn4O3X] core (X = benzoate, acetate, methoxide, hydroxide, azide, fluoride, chloride or bromide). In addition, Mn4O3Cl complexes containing three or six terminal Cl ligands at three of the Mn were included in this study. The EXAFS method detects the small changes in the core structures as X is varied in this series, and serves to exclude these distorted cubanes of C3v symmetry as a topological model for the Mn catalytic cluster. The sulfur K-edge x-ray absorption near-edge structure (XANES) spectra for the amino acids cysteine, methionine, their corresponding oxidized forms cystine and methionine sulfoxide, and

  15. Structural study of thin films prepared from tungstate glass matrix by Raman and X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Montanari, Bianca; Barbosa, Anne J.; Ribeiro, Sidney J.L.; Messaddeq, Younes [Departamento de Quimica Geral e Inorganica, Instituto de Quimica, UNESP, CP 355, CEP 14800-900 Araraquara, SP (Brazil); Poirier, Gael [Departamento de Ciencias Exatas, UNIFAL-MG, CEP 37130-000 Alfenas, MG (Brazil)], E-mail: gael@unifal-mg.edu.br; Li, Maximo S. [Instituto de Fisica, USP, CP 369, CEP 13560-970 Sao Carlos, SP (Brazil)

    2008-06-30

    Thin films were prepared using glass precursors obtained in the ternary system NaPO{sub 3}-BaF{sub 2}-WO{sub 3} and the binary system NaPO{sub 3}-WO{sub 3} with high concentrations of WO{sub 3} (above 40% molar). Vitreous samples have been used as a target to prepare thin films. Such films were deposited using the electron beam evaporation method onto soda-lime glass substrates. Several structural characterizations were performed by Raman spectroscopy and X-ray Absorption Near Edge Spectroscopy (XANES) at the tungsten L{sub I} and L{sub III} absorption edges. XANES investigations showed that tungsten atoms are only sixfold coordinated (octahedral WO{sub 6}) and that these films are free of tungstate tetrahedral units (WO{sub 4}). In addition, Raman spectroscopy allowed identifying a break in the linear phosphate chains as the amount of WO{sub 3} increases and the formation of P-O-W bonds in the films network indicating the intermediary behavior of WO{sub 6} octahedra in the film network. Based on XANES data, we suggested a new attribution of several Raman absorption bands which allowed identifying the presence of W-O{sup -} and W=O terminal bonds and a progressive apparition of W-O-W bridging bonds for the most WO{sub 3} concentrated samples (above 40% molar) attributed to the formation of WO{sub 6} clusters.

  16. Low Z elements (Mg, Al, and Si) K-edge X-ray absorption spectroscopy in minerals and disordered systems

    International Nuclear Information System (INIS)

    Ildefonse, P.; Calas, G.; Flank, A.M.; Lagarde, P.

    1995-01-01

    Soft X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy have been performed at the Mg-, Al- and Si-K edges in order to establish the ability of this spectroscopy to derive structural information in disordered solids such as glasses and gels. Mg- and Al-K XANES are good structural probes to determine the coordination state of these elements in important minerals, glasses and gels. In a CaO-MgO-2SiO 2 glass Mg XANES spectra differ from that found in the crystalline equivalent, with a significant shift of the edge maxima to lower energy, consistent with a CN lower than 6. Mg-EXAFS on the same sample are in agreement and indicate the presence of 5-coordinated Mg with Mg-O distances of 2.01 A. In aluminosilicate gels, Al-K XANES has been used to investigate the [4]Al/Al total ratios. These ratios increase as the Al/Si ratios decrease. Aluminosilicate and ferric-silicate gels were studied by using Si-K edge XANES. XANES spectra differ significantly among the samples studied. Aluminosilicate gels with Al/Si=1 present a different Al and Si local environment from that known in clay minerals with the same Al/Si ratio. The gel-to-mineral transformation thus implies a dissolution-recrystallization mechanism. On the contrary, ferric-silicate gel presents a Si local environment close to that found in nontronite which may be formed by a long range ordering of the initial gels. (orig.)

  17. Low Z elements (Mg, Al, and Si) K-edge X-ray absorption spectroscopy in minerals and disordered systems

    Science.gov (United States)

    Ildefonse, Ph.; Calas, G.; Flank, A. M.; Lagarde, P.

    1995-05-01

    Soft X-ray absorption near edge spectroscopy (XANES) and extended X-ray absorption fine structure (EXAFS) spectroscopy have been performed at the Mg-, Al- and Si-K edges in order to establish the ability of this spectroscopy to derive structural information in disordered solids such as glasses and gels. Mg- and Al-K XANES are good structural probes to determine the coordination state of these elements in important minerals, glasses and gels. In a CaOsbnd MgOsbnd 2SiO2 glass Mg XANES spectra differ from that found in the crystalline equivalent, with a significant shift of the edge maxima to lower energy, consistent with a CN lower than 6. Mg-EXAFS on the same sample are in agreement and indicate the presence of 5-coordinated Mg with Mgsbnd O distances of 2.01Å. In aluminosilicate gels, Alsbnd K XANES has been used to investigate the [4]Al/Altotal ratios. These ratios increase as the Al/Si ratios decrease. Aluminosilicate and ferric-silicate gels were studied by using Sisbnd K edge XANES. XANES spectra differ significantly among the samples studied. Aluminosilicate gels with Al/Si= 1 present a different Al and Si local environment from that known in clay minerals with the same Al/Si ratio. The gel-to-mineral transformation thus implies a dissolution-recrystallization mechanism. On the contrary, ferric-silicate gel presents a Si local environment close to that found in nontronite which may be formed by a long range ordering of the initial gels.

  18. Medieval glass from the Cathedral in Paderborn: a comparative study using X-ray absorption spectroscopy, X-ray fluorescence, and inductively coupled laser ablation mass spectrometry

    Energy Technology Data Exchange (ETDEWEB)

    Hormes, J. [University of Saskatchewan, Canadian Light Source Inc., Saskatoon, SK (Canada); Louisiana State University, CAMD, Baton Rouge, LA (United States); Roy, A.; Bovenkamp, G.L. [Louisiana State University, CAMD, Baton Rouge, LA (United States); Simon, K. [University of Goettingen, Geochemistry, Centre for Geosciences, Goettingen (Germany); Kim, C.Y. [University of Saskatchewan, Canadian Light Source Inc., Saskatoon, SK (Canada); Boerste, N. [Faculty for Theology Paderborn, Paderborn (Germany); Gai, S. [LWL - Archaeologie fuer Westfalen, Muenster (Germany)

    2013-04-15

    We have investigated four stained glass samples recovered from an archaeological excavation at the Cathedral in Paderborn (Germany) between 1978 and 1980. On two of the samples there are parts of paintings. Concentrations of major elements were determined using two independent techniques: LA-ICP-MS (a UV laser ablation microsampler combined with an inductively coupled plasma mass spectrometer) and synchrotron radiation X-ray excited X-ray fluorescence (SR-XRF). The SR-XRF data were quantified by using the program package PyMCA developed by the software group of the ESRF in Grenoble. Significant differences were found between the concentrations determined by the two techniques that can be explained by concentration gradients near the surface of the glasses caused, for example, by corrosion/leaching processes and the different surface sensitivities of the applied techniques. For several of the elements that were detected in the glass and in the colour pigments used for the paintings X-ray absorption near edge structure (XANES) spectra were recorded in order to determine the chemical speciation of the elements of interest. As was expected, most elements in the glass were found as oxides in their most stable form. Two notable exceptions were observed: titanium was not found as rutile - the most stable form of TiO{sub 2} - but in the form of anatase, and lead was not found in one defined chemical state but as a complex mixture of oxide, sulphate, and other compounds. (orig.)

  19. Combining Sequential Extractions and X-ray Absorption Spectroscopy for Quantitative and Qualitative Zinc Speciation in Soil

    Science.gov (United States)

    Bauer, Tatiana; Minkina, Tatiana; Batukaev, Abdulmalik; Nevidomskaya, Dina; Burachevskaya, Marina; Tsitsuashvili, Viktoriya; Urazgildieva, Kamilya

    2017-04-01

    The combined use of X-ray absorption spectrometry and extractive fractionation is an effective approach for studying the interaction of metal ions with soil compounds and identifying the phases-carriers of metals in soil and their stable fixation. These studies were carried out using the technique of X-ray absorption spectroscopy and chemical extractive fractionation. In a model experiment the samples taken in Calcic Chernozem were artificially contaminated with higher portion of Zn(NO3)2 (2000 mg/kg). The metal were incubated in soil samples for 2 year. The samples of soil mineral and organic phases (calcite, kaolinite, bentonite, humic acids) were saturated with Zn2+ from a solution of nitrate salts of metal. The total content of Zn in soil and soil various phases was determined using the X-ray fluorescence method. Extended X-ray absorption fine structure (EXAFS) Zn was measured at the Structural Materials Science beamline of the Kurchatov Center for Synchrotron Radiation. Sequential fractionation of Zn in soil conducted by Tessier method (Tessier et al., 1979) which determining 5 fractions of metals in soil: exchangeable, bound to Fe-Mn oxide, bound to carbonate, bound to the organic matter, and bound to silicate (residual). This methodology has so far more than 4000 citations (Web of Science), which demonstrates the popularity of this approach. Much Zn compounds are contained in uncontaminated soils in stable primary and secondary silicates inherited from the parental rocks (67% of the total concentrations in all fractions), which is a regional trait of soils in the fore-Caucasian plain. Extracted fractionation of metal compounds in soil samples, artificially contaminated with Zn salts, indicates the priority holding of Zn2+ ions by silicates, carbonates and Fe-Mn oxides. The Zn content significantly increases in the exchangeable fraction. Atomic structure study of the soil various phases saturated with Zn2+ ion by using (XANES) X-ray absorption spectroscopy

  20. Fe K-EDGE X-RAY ABSORPTION SPECTROSCOPY OF SILICATE MINERALS AND GLASSES

    OpenAIRE

    Binsted , N.; Greaves , G.; Henderson , C.

    1986-01-01

    Structural parameters determined for crystalline iron, fayalite and aegirine agree closely with X-ray crystallograhic data. A glass of NaFeSi2O6 composition has Fe predominantly present as Fe3+ in tetrahedral coordination i.e. as a network former. CaFeSiO4 and CaFeSi2O6 glasses have about 1/3 of the total Fe in octahedral coordination i.e. as a network modifier.

  1. In-situ X-ray absorption spectroscopy analysis of capacity fade in nanoscale-LiCoO{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Patridge, Christopher J. [NRC/NRL Cooperative Research Associate, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Love, Corey T., E-mail: corey.love@nrl.navy.mil [Chemistry Division, Code 6113, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Swider-Lyons, Karen E. [Chemistry Division, Code 6113, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Twigg, Mark E. [Electronics Science and Technology Division, Code 6812, U.S. Naval Research Laboratory, Washington, DC 20375 (United States); Ramaker, David E. [Chemistry Division, Code 6189, U.S. Naval Research laboratory, Washington, DC 20375 (United States)

    2013-07-15

    The local structure of nanoscale (∼10–40 nm) LiCoO{sub 2} is monitored during electrochemical cycling utilizing in-situ X-ray absorption spectroscopy (XAS). The high surface area of the LiCoO{sub 2} nanoparticles not only enhances capacity fade, but also provides a large signal from the particle surface relative to the bulk. Changes in the nanoscale LiCoO{sub 2} metal-oxide bond lengths, structural disorder, and chemical state are tracked during cycling by adapting the delta mu (Δμ) technique in complement with comprehensive extended X-ray absorption fine structure (EXAFS) modeling. For the first time, we use a Δμ EXAFS method, and by comparison of the difference EXAFS spectra, extrapolate significant coordination changes and reduction of cobalt species with cycling. This combined approach suggests Li–Co site exchange at the surface of the nanoscale LiCoO{sub 2} as a likely factor in the capacity fade and irreversible losses in practical, microscale LiCoO{sub 2}. - Graphical abstract: Electrochemical cycling of Li-ion batteries has strong impact on the structure and integrity of the cathode active material particularly near the surface/electrolyte interface. In developing a new method, we have used in-situ X-ray absorption spectroscopy during electrochemical cycling of nanoscale LiCoO{sub 2} to track changes during charge and discharge and between subsequent cycles. Using difference spectra, several small changes in Co-O bond length, Co-O and Co-Co coordination, and site exchange between Co and Li sites can be tracked. These methods show promise as a new technique to better understand processes which lead to capacity fade and loss in Li-ion batteries. - Highlights: • A new method is developed to understand capacity fade in Li-ion battery cathodes. • Structural changes are tracked during Li intercalation/deintercalation of LiCoO{sub 2}. • Surface structural changes are emphasized using nanoscale-LiCoO{sub 2} and difference spectra. • Full multiple

  2. In-situ X-ray absorption spectroscopy analysis of capacity fade in nanoscale-LiCoO2

    International Nuclear Information System (INIS)

    Patridge, Christopher J.; Love, Corey T.; Swider-Lyons, Karen E.; Twigg, Mark E.; Ramaker, David E.

    2013-01-01

    The local structure of nanoscale (∼10–40 nm) LiCoO 2 is monitored during electrochemical cycling utilizing in-situ X-ray absorption spectroscopy (XAS). The high surface area of the LiCoO 2 nanoparticles not only enhances capacity fade, but also provides a large signal from the particle surface relative to the bulk. Changes in the nanoscale LiCoO 2 metal-oxide bond lengths, structural disorder, and chemical state are tracked during cycling by adapting the delta mu (Δμ) technique in complement with comprehensive extended X-ray absorption fine structure (EXAFS) modeling. For the first time, we use a Δμ EXAFS method, and by comparison of the difference EXAFS spectra, extrapolate significant coordination changes and reduction of cobalt species with cycling. This combined approach suggests Li–Co site exchange at the surface of the nanoscale LiCoO 2 as a likely factor in the capacity fade and irreversible losses in practical, microscale LiCoO 2 . - Graphical abstract: Electrochemical cycling of Li-ion batteries has strong impact on the structure and integrity of the cathode active material particularly near the surface/electrolyte interface. In developing a new method, we have used in-situ X-ray absorption spectroscopy during electrochemical cycling of nanoscale LiCoO 2 to track changes during charge and discharge and between subsequent cycles. Using difference spectra, several small changes in Co-O bond length, Co-O and Co-Co coordination, and site exchange between Co and Li sites can be tracked. These methods show promise as a new technique to better understand processes which lead to capacity fade and loss in Li-ion batteries. - Highlights: • A new method is developed to understand capacity fade in Li-ion battery cathodes. • Structural changes are tracked during Li intercalation/deintercalation of LiCoO 2 . • Surface structural changes are emphasized using nanoscale-LiCoO 2 and difference spectra. • Full multiple scattering calculations are used to

  3. Electronic structure study of Co doped CeO2 nanoparticles using X-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Kumar, Shalendra; Gautam, Sanjeev; Song, T.K.; Chae, Keun Hwa; Jang, K.W.; Kim, S.S.

    2014-01-01

    Highlights: • The electronic structural of Co–CeO 2 nanoparticles is investigated using XAFS. • Ce M 5,4 , Ce L 3 and O K edge NEXAFS reveal that the Ce-ions are in +4 valence state. • The NEXAFS spectrum performed at Co L3,2-edge confirms Co-ion in 2+ state. • The EXAFS analysis also show that Co ions are occupying Ce position in doped CeO 2 . • The distances between Ce–O and Ce–Ce/Co in all shells decreases with Co doping. - Abstract: We investigated the electronic structure of well characterized Co doped CeO 2 nanoparticles using X-ray absorption fine structure (XAFS) spectroscopy. Near edge X-ray absorption fine structure (NEXAFS) spectra at Ce M 5,4 , Ce L 3 and O K-edge conclude that the Ce-ions are in +4 valence state in pure as well as in Co doped CeO 2 nanoparticles. The local structure around Ce-atom in Co doped CeO 2 nanoparticles was also determined using extended X-ray absorption fine structure (EXAFS) spectroscopy at Ce L 3 edge. The EXAFS analysis suggest that the inter-atomic distance of Ce–O, Ce–Ce/Co decreases with Co doping, which indicate a contraction of the lattice. The decease in Ce–O distance also reflect that there is a formation of oxygen vacancies in CeO 2 matrix. The Debye–Waller factor also shows the consistent behaviour for all the coordination shells. The atomic multiplet calculations for Co L 3,2 -edge was performed to determine the valence state, symmetry and field splitting, which reflect that Co-ions are in 2+ state and substituted at Ce-site with crystal field splitting of 10Dq=-0.57eV. The XAFS measurements reveal that the Co-ions occupy the Ce position in the CeO 2 host matrix and create a oxygen vacancy

  4. Kinetics of iron redox reactions in silicate liquids: A high-temperature X-ray absorption and Raman spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Magnien, V. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France); CEA VALRHO Marcoule, SCDV, LEBV, BP 17171, 30207 Bagnols/Ceze (France); Neuville, D.R. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France)]. E-mail: neuville@ipgp.jussieu.fr; Cormier, L. [IMPMC, CNRS UMR 7590, Universites Paris 6 and 7 and IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France); Roux, J. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France); Hazemann, J.-L. [Laboratoire de cristallographie, UPR 5031, CNRS, 38043 Grenoble (France); Pinet, O. [CEA VALRHO Marcoule, SCDV, LEBV, BP 17171, 30207 Bagnols/Ceze (France); Richet, P. [Physique des Mineraux et Magmas, CNRS-IPGP, 4 place Jussieu, 75252 Paris cedex 05 (France)

    2006-06-30

    The oxidation kinetics of a Fe-bearing supercooled liquid of the system SiO{sub 2}-CaO-MgO-Na{sub 2}O-FeO has been determined near the glass transition range by X-ray absorption near edge structure (XANES) and Raman spectroscopies. Both techniques yield room-temperature iron redox ratios in accord with wet chemical, Moessbauer and electron microprobe analyses. Similar oxidation kinetics have also been observed with both methods. At constant temperature, the kinetics obey an exponential law with a characteristic time that follows an Arrhenian temperature dependence. As redox changes are too fast to be accounted for in terms of diffusion of either ionic or molecular oxygen, these results lend further support to the idea that the rate-limiting factor for oxidation near the glass transition is diffusion of network-modifying cations along with a flux of electron holes.

  5. In situ time-resolved X-ray near-edge absorption spectroscopy of selenite reduction by siderite

    International Nuclear Information System (INIS)

    Badaut, V.; Schlegel, M.L.; Descostes, M.; Moutiers, G.

    2012-01-01

    The reduction oxidation-reaction between aqueous selenite (SeO 3 2- ) and siderite (FeCO 3 (s)) was monitored by in situ, time-resolved X-ray absorption near-edge structure (XANES) spectroscopy at the selenium K edge in a controlled electrochemical environment. Spectral evolutions showed that more than 60% of selenite was reduced at the siderite surface after 20 h of experiment, at which time the reaction was still incomplete. Fitting of XANES spectra by linear combination of reference spectra showed that selenite reaction with siderite is essentially a two-step process, selenite ions being immobilized on siderite surface prior to their reduction. A kinetic model of the reduction step is proposed, allowing to identify the specific contribution of surface reduction. These results have strong implications for the retention of selenite by corrosion products in nuclear waste repositories and in a larger extent for the fate of selenium in the environment. (authors)

  6. Direct Structural and Chemical Characterization of the Photolytic Intermediates of Methylcobalamin Using Time-Resolved X-ray Absorption Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Subramanian, Ganesh; Zhang, Xiaoyi; Kodis, Gerdenis; Kong, Qingyu; Liu, Cunming; Chizmeshya, Andrew; Weierstall, Uwe; Spence, John

    2018-04-05

    Cobalt−carbon bond cleavage is crucial to most natural and synthetic applications of the cobalamin class of compounds, and here we present the first direct electronic and geometric structural characteristics of intermediates formed following photoexcitation of methylcobalamin (MeCbl) using time-resolved X-ray absorption spectroscopy (XAS). We catch transients corresponding to two intermediates, in the hundreds of picoseconds and a few microseconds. Highlights of the picosecond intermediate, which is reduced in comparison to the ground state, are elongation of the upper axial Co−C bond and relaxation of the corrin ring. This is not so with the recombining photocleaved products captured at a few microseconds, where the Co−C bond almost (yet not entirely) reverts to its ground state configuration and a substantially elongated lower axial Co−NIm bond is observed. The reduced cobalt site here confirms formation of methyl radical as the photoproduct.

  7. Image stack alignment in full-field X-ray absorption spectroscopy using SIFT_PyOCL.

    Science.gov (United States)

    Paleo, Pierre; Pouyet, Emeline; Kieffer, Jérôme

    2014-03-01

    Full-field X-ray absorption spectroscopy experiments allow the acquisition of millions of spectra within minutes. However, the construction of the hyperspectral image requires an image alignment procedure with sub-pixel precision. While the image correlation algorithm has originally been used for image re-alignment using translations, the Scale Invariant Feature Transform (SIFT) algorithm (which is by design robust versus rotation, illumination change, translation and scaling) presents an additional advantage: the alignment can be limited to a region of interest of any arbitrary shape. In this context, a Python module, named SIFT_PyOCL, has been developed. It implements a parallel version of the SIFT algorithm in OpenCL, providing high-speed image registration and alignment both on processors and graphics cards. The performance of the algorithm allows online processing of large datasets.

  8. A superconducting tunneling junction (STJ) detector for soft X-ray absorption spectroscopy at 50 mK

    International Nuclear Information System (INIS)

    Baev, Ivan; Ruescher, Jan-Hendrik; Martins, Michael; Viefhaus, Jens; Wurth, Wilfried

    2016-01-01

    Soft X-ray absorption spectroscopy (XAS) is an important technique at synchrotrons nowadays that allows to investigate electronic and magnetic properties in an element specific way. The investigation of non-conductive, soft organic or buried materials can't be carried out in total electron yield. In these cases an efficient fluorescence detector is needed to perform XAS measurements in partial fluorescence yield (PFY). The STJ detector is capable of count rates as high as 10 kcps per 100 μm"2 pixel size with an energy resolution of approximately 50 eV for 1.5 keV photons. The STJ is furthermore integrated into a 50 mK cryostat for XAS measurements at the P04 beamline at Petra III, DESY. We will present first measurements on a model system.

  9. Sulfur K-edge X-ray absorption spectroscopy as an experimental probe for S-nitroso proteins

    International Nuclear Information System (INIS)

    Szilagyi, Robert K.; Schwab, David E.

    2005-01-01

    X-ray absorption spectroscopy at the sulfur K-edge (2.4-2.6 keV) provides a sensitive and specific technique to identify S-nitroso compounds, which have significance in nitric oxide-based cell signaling. Unique spectral features clearly distinguish the S-nitroso-form of a cysteine residue from the sulfhydryl-form or from a methionine thioether. Comparison of the sulfur K-edge spectra of thiolate, thiol, thioether, and S-nitroso thiolate compounds indicates high sensitivity of energy positions and intensities of XAS pre-edge features as determined by the electronic environment of the sulfur absorber. A new experimental setup is being developed for reaching the in vivo concentration range of S-nitroso thiol levels in biological samples

  10. Electrochemical kinetics and X-ray absorption spectroscopy investigations of select chalcogenide electrocatalysts for oxygen reduction reaction applications

    International Nuclear Information System (INIS)

    Ziegelbauer, Joseph M.; Murthi, Vivek S.; O'Laoire, Cormac; Gulla, Andrea F.; Mukerjee, Sanjeev

    2008-01-01

    Transition metal-based chalcogenide electrocatalysts exhibit a promising level of performance for oxygen reduction reaction applications while offering significant economic benefits over the state of the art Pt/C systems. The most active materials are based on Ru x Se y clusters, but the toxicity of selenium will most likely limit their embrace by the marketplace. Sulfur-based analogues do not suffer from toxicity issues, but suffer from substantially less activity and stability than their selenium brethren. The structure/property relationships that result in these properties are not understood due to ambiguities regarding the specific morphologies of Ru x S y -based chalcogenides. To clarify these properties, an electrochemical kinetics study was interpreted in light of extensive X-ray diffraction, scanning electron microscopy, and in situ X-ray absorption spectroscopy evaluations. The performance characteristics of ternary M x Ru y S z /C (M = Mo, Rh, or Re) chalcogenide electrocatalysts synthesized by the now-standard low-temperature nonaqueous (NA) route are compared to commercially available (De Nora) Rh- and Ru-based systems. Interpretation of performance differences is made in regards to bulk and surface properties of these systems. In particular, the overall trends of the measured activation energies in respect to increasing overpotential and the gross energy values can be explained in regards to these differences

  11. Incorporation of Trace Elements in Ancient and Modern Human Bone: An X-Ray Absorption Spectroscopy Study

    Science.gov (United States)

    Pingitore, N. E.; Cruz-Jimenez, G.; Price, T. D.

    2001-12-01

    X-ray absorption spectroscopy (XAS) affords the opportunity to probe the atomic environment of trace elements in human bone. We are using XAS to investigate the mode(s) of incorporation of Sr, Zn, Pb, and Ba in both modern and ancient (and thus possibly altered) human and animal bone. Because burial and diagenesis may add trace elements to bone, we performed XAS analysis on samples of pristine contemporary and ancient, buried human and animal bone. We assume that deposition of these elements during burial occurs by processes distinct from those in vivo, and this will be reflected in their atomic environments. Archaeologists measure strontium in human and animal bone as a guide to diet. Carnivores show lower Sr/Ca ratios than their herbivore prey due to discrimination against Sr relative to Ca up the food chain. In an initial sample suite no difference was observed between modern and buried bone. Analysis of additional buried samples, using a more sensitive detector, revealed significant differences in the distance to the second and third neighbors of the Sr in some of the buried samples. Distances to the first neighbor, oxygen, were similar in all samples. Zinc is also used in paleo-diet studies. Initial x-ray absorption spectroscopy of a limited suite of bones did not reveal any differences between modern and buried samples. This may reflect the limited number of samples examined or the low levels of Zn in typical aqueous solutions in soils. Signals from barium and lead were too low to record useful XAS spectra. Additional samples will be studied for Zn, Ba, and Pb. We conducted our XAS experiments on beam lines 4-1 and 4-3 at the Stanford Synchrotron Radiation Laboratory. Data were collected in the fluorescence mode, using a Lytle detector and appropriate filter, and a solid state, 13-element Ge-detector.

  12. Double resonance capacitance spectroscopy (DORCAS): A new experimental technique for assignment of X-ray absorption peaks to surface sites of semiconductor

    CERN Document Server

    Ishii, M

    2003-01-01

    As a new microspectroscopy for semiconductor surface analysis using an X-ray beam, double resonance capacitance spectroscopy (DORCAS) is proposed. For a microscopic X-ray absorption measurement, a local capacitance change owing to X-ray induced emission of localized electrons is detected by a microprobe. The applied bias voltage V sub b dependence of the capacitance also provides information on the surface density of state. The resonance of the Fermi energy with a surface level by V sub b control makes possible the selection of the observable surface site in the X-ray absorption measurements, i.e. site-specific spectroscopy. The double resonance of the surface site selection (V sub b resonance) and the resonant X-ray absorption of the selected site (photon energy h nu resonance) enhances the capacitance signal. The DORCAS measurement of the GaAs surface shows correlation peaks at h nu=10.402 keV and V sub b =-0.4 V and h nu=10.429 keV and V sub b =+0.1 V, indicating that these resonant X-ray absorption peaks ...

  13. First X-Ray absorption spectroscopy results on Aeolian dust archived in Antarctica and Alpine firn cores

    Science.gov (United States)

    Marcelli, A.; Maggi, V.; Cibin, G.; Sala, M.; Marino, F.; Delmonte, B.

    2006-12-01

    We present the first x-ray absorption spectroscopy (XAS) data at the Fe K-edge collected on insoluble mineral dust from Talos Dome firn core (TDC, 159°04'E, 72°46'S, 2316 m a.s.l., mean accumulation rate 8 g cm-2 yr- 1), drilled in the framework of the International Trans Antarctic Scientific Expedition (ITASE), and from a Colle del Lys 2003 firn core (CDL03, 45°92'N, 7°86'E, 4248m a.s.l., mean accumulation rate 134 g cm-2 yr-1, Lys Glacier, Mt. Rosa, Italy). The low concentration of mineral particles, obtained by filtering each firn core melted samples on Nuclepore membranes in a 1000 class clean room, required a specific procedure to prepare the samples necessary to the successful collection of the XAS data. The firn samples were decontaminated in clean room under laminar flow bench by means of a ceramic knife and discarding the external part of the cores. Analyses of the insoluble particle content were performed by particle counter Beckman CounterãMultisizer III in order to defined concentration and size distribution of particles in each samples. A dedicated HV experimental chamber, devoted to the realization of XAS experiments on very low absorber concentration samples, was developed and realized in the framework of the CryoAlp collaboration at IMONT, the Italian National Institute for Mountains. The original experimental setup, thanks to the presence of an in-vacuum sample micromanipulator and special sample alignment and docking system installed for these experiments at the Stanford Synchrotron Radiation Laboratory at the beamline 6-2, allows both normal-incidence X-ray Fluorescence detection using a Ketek SDD detector having an energy resolution of about 150 eV and extremely low energy detection limit, and Total X-ray Reflection Fluorescence and Absorption Spectroscopy measurements. The high quality of the XANES experiments performed, using both normal incidence and Total Reflection XAS measurements, allowed recognizing iron-inclusion mineral fractions

  14. Theory of X-ray absorption and emission spectra

    International Nuclear Information System (INIS)

    Mukoyama, Takeshi

    2004-01-01

    Theoretical studies on X-ray absorption and emission spectroscopy are discussed. Simple expressions for X-ray emission rate and X-ray absorption cross section are presented in the dipole approximation. Various atomic models to obtain realistic wave functions and theoretical calculations for X-ray absorption cross sections and X-ray emission rates are described. In the case of molecules and solids, molecular orbital methods for electronic structures and molecular wave functions are discussed. The emphasis is on the procedures to obtain the excited-state and continuum wave functions for molecules and to calculate the multi-center dipole matrix elements. The examples of the calculated X-ray absorption and emission spectra are shown and compared with the experimental results

  15. X-ray absorption and resonant photoelectron spectroscopy of epitaxial Fe-doped SrTiO{sub 3}

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, Annemarie; Lenser, Christian; Xu, Chencheng; Wicklein, Sebastian; Dittmann, Regina [Peter Gruenberg Institut 7, Forschungszentrum Juelich GmbH (Germany); Kajewski, Dariusz; Kubacki, Jurek; Szade, Jacek [A.Chelkowski Institute of Physics, University of Silesia, Katowic (Poland)

    2012-07-01

    In recent years resistive switching in transition metal oxides received a lot of research interest due to the proposed application as non-volatile data memory. SrTiO{sub 3} serves as a model system for the investigation of resistive switching due to the valency change mechanism. Frequently, slightly Fe doping is used, as it has shown to improve the switching properties. The focus of this study is the effect of Fe-doping of SrTiO{sub 3} in thin epitaxial films. Thin film samples with Fe concentration of 2 at.% and 5 at.% were prepared by pulsed laser deposition at varying substrate temperatures. The surface morphology of the films is studied with AFM. X-ray absorption spectroscopy is performed in total-electron and auger-electron yield offering different probing depths. Significant variations of the Fe-L edge between bulk and interface as well as after annealing are observed and discussed in terms of integration into the lattice and evolution of secondary phases. Resonant photoelectron spectroscopy at the absorption edge of Ti, O and Fe was used to determine the spectral contributions to the valence band. Most noteworthy we find significant spectral weight above the valence band, which can be attributed to Fe-states.

  16. High energy resolution off-resonant X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Wojciech, Blachucki [Univ. of Fribourg (Switzerland). Dept. of Physics

    2015-10-16

    This work treats of the high energy resolution off-resonant X-ray spectroscopy (HEROS) method of determining the density of unoccupied electronic states in the vicinity of the absorption edge. HEROS is an alternative to the existing X-ray absorption spectroscopy (XAS) methods and opens the way for new studies not achievable before.

  17. The problem of channel dependence in foil-absorption X-ray spectroscopy

    International Nuclear Information System (INIS)

    Rodriguez-Trelles, F.; Caputo, M.C.

    1986-01-01

    We analyze the interdependence among measurements of X-ray spectra in the energy range 4-60 keV by a multi-channel instrument. Two methods of estimating it are described. One gives the error magnification expected in spectrum deconvolution resulting from the covariance matrix of the products of filter transmission times detector sensitivity, evaluated over the whole accessible range of photon energies. The other is an extension of the former evaluating the covariance matrices over consecutive energy bands. This extension allows one to analyze channel dependence for each band, thus improving the prospects of filter and detector selection in the design of an experiment. We present tables showing the expected behaviors of several combinations of filters (homogeneous, heterogeneous, doublets, Ross) and detectors (flat, film, diodes). The advantages of heterogeneous filters are emphasized. (orig.)

  18. Soft x-ray irradiation effects of Li₂O₂, Li₂CO₃ and Li₂O revealed by absorption spectroscopy.

    Directory of Open Access Journals (Sweden)

    Ruimin Qiao

    Full Text Available Li(2O(2, Li(2CO(3, and Li(2O are three critical compounds in lithium-air and lithium-ion energy storage systems. Extensive measurements have been carried out to study the chemical species and their evolutions at difference stages of the device operation. While x-ray spectroscopy has been demonstrated to be one of the most powerful tools for such purpose, no systematic study on the irradiation effects have been reported. Here we carry out extensive time, position, and irradiation dependent Li K-edge soft x-ray absorption spectroscopy on these compounds with so far the best energy resolution. The ultra-high resolution in the current study allows the features in the absorption spectra to be well-resolved. The spectral lineshape thus serves as the fingerprints of these compounds, enabling the tracking of their evolution under x-ray irradiation. We found that both Li(2O(2 and Li(2CO(3 evidently evolve towards Li(2O under the soft x-ray irradiation with Li(2CO(3 exhibiting a surprisingly higher sensitivity to x-rays than Li(2O(2. On the other hand, Li(2O remains the most stable compound despite experiencing substantial irradiation dose. We thus conclude that high resolution soft x-ray spectroscopy could unambiguously fingerprint different chemical species, but special cautions on irradiation effects would be needed in performing the experiments and interpreting the data properly.

  19. Electrosynthesis of ZnO nanorods and nanotowers: Morphology and X-ray Absorption Near Edge Spectroscopy studies

    Science.gov (United States)

    Sigircik, Gokmen; Erken, Ozge; Tuken, Tunc; Gumus, Cebrail; Ozkendir, Osman M.; Ufuktepe, Yuksel

    2015-06-01

    Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. The resulting opto-electronic properties were interpreted extensively, using X-ray diffraction (XRD), X-ray Absorption Near Edge Spectroscopy (XANES), field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy and four probe techniques. The ZnO deposition is mass transport controlled process and the interaction of chloride ions with the surface has great influence on diffusion kinetics, considering the substantial species (Zn2+ and OH-) involved in the construction of ZnO film. This effect does not change major lattice parameters, as shown with detailed analysis of XRD data. However, the texture coefficient (Tc) (0 0 2) value is higher in presence of chloride ions containing synthesis solution which gave vertically aligned, well defined and uniformly dispersed nanorods structure. The calculated Eg values are in the range 3.28-3.41 eV and 3.22-3.31 eV for ZnO nanorods and nanotowers synthesized at different deposition periods, respectively. Furthermore, the charge mobility values regarding the deposition periods were measured to be in the ranges from 130.4 to 449.2 cm2 V-1 s-1 and 126.2 to 204.7 cm2 V-1 s-1 for nanorods and nanotowers, respectively. From XANES results, it was shown that the Zn K-edge spectrum is dominated by the transition of Zn 1s core electrons into the unoccupied Zn 4p states of the conduction band. Comparing the rod and tower nano-structured ZnO thin films, the excitation behavior of valence band electrons is different. Moreover, the density states of Zn 4p are higher for ZnO nanorods.

  20. Comparison of conventional and total reflection excitation geometry for fluorescence X-ray absorption spectroscopy on droplet samples

    International Nuclear Information System (INIS)

    Falkenberg, G.; Pepponi, G.; Streli, C.; Wobrauschek, P.

    2003-01-01

    X-ray absorption fine structure (XAFS) experiments in fluorescence mode have been performed in total reflection excitation geometry and conventional 45 deg. /45 deg. excitation/detection geometry for comparison. The experimental results have shown that XAFS measurements are feasible under normal total reflection X-ray fluorescence (TXRF) conditions, i.e. on droplet samples, with excitation in grazing incidence and using a TXRF experimental chamber. The application of the total reflection excitation geometry for XAFS measurements increases the sensitivity compared to the conventional geometry leading to lower accessible concentration ranges. However, XAFS under total reflection excitation condition fails for highly concentrated samples because of the self-absorption effect

  1. Soft x-ray absorption spectroscopy on Co doped ZnO: structural distortions and electronic structure

    International Nuclear Information System (INIS)

    Kowalik, I A; Guziewicz, E; Godlewski, M; Arvanitis, D

    2016-01-01

    We present soft x-ray absorption spectra from a series of Co doped ZnO films. We discuss systematic variations of the Co L-edge white line intensity and multiplet features for this series of samples. We document sizeable differences in the electronic state of the Co ionic cores, as well as in the local environment of the host lattice atoms, characterised by means of x-ray absorption spectra at the O K-edge and Zn L-edges. Model calculations allow to correlate the observed effects to small structural distortions of the ZnO lattice. (paper)

  2. Debris of potassium–magnesium silicate glass generated by femtosecond laser-induced ablation in air: An analysis by near edge X-ray absorption spectroscopy, micro Raman and energy dispersive X-ray spectroscopy

    International Nuclear Information System (INIS)

    Grehn, M.; Seuthe, T.; Reinhardt, F.; Höfner, M.; Griga, N.; Eberstein, M.; Bonse, J.

    2014-01-01

    The redeposited material (debris) resulting from ablation of a potassium–magnesium silicate glass upon scanning femtosecond laser pulse irradiation (130 fs, 800 nm) in air environment is investigated by means of three complementary surface analytical methods. Changes in the electronic band structure of the glass constituent Magnesium (Mg) were identified by X-ray Absorption Near Edge Structure spectroscopy (XANES) using synchrotron radiation. An up-shift of ≈0.8 eV of a specific Magnesium K-edge absorption peak in the spectrum of the redeposited material along with a significant change in its leading edge position was detected. In contrast, the surface left after laser ablation exhibits a downshift of the peak position by ≈0.9 eV. Both observations may be related to a change of the Mg coordinative state of the laser modified/redeposited glass material. The presence of carbon in the debris is revealed by micro Raman spectroscopy (μ-RS) and was confirmed by energy dispersive X-ray spectroscopy (EDX). These observations are attributed to structural changes and chemical reactions taking place during the ablation process.

  3. Manganese L-edge X-ray absorption spectroscopy of manganese catalase from Lactobacillus plantarum and mixed valence manganese complexes

    Energy Technology Data Exchange (ETDEWEB)

    Grush, M.M.; Chen, J.; George, S.J. [Univ. of California, Davis, CA (United States)] [and others

    1996-01-10

    The first Mn L-edge absorption spectra of a Mn metalloprotein are presented in this paper. Both reduced and superoxidized Mn catalase have been examined by fluorescence-detected soft X-ray absorption spectroscopy, and their Mn L-edge spectra are dramatically different. The spectrum of reduced Mn(II)Mn(II) catalase has been interpreted by ligand field atomic multiplet calculations and by comparison to model compound spectra. The analysis finds a 10 Dq value of nearly 1.1 eV, consistent with coordination by predominately nitrogen and oxygen donor ligands. For interpretation of mixed valence Mn spectra, an empirical simulation procedure based on the addition of homovalent model compound spectra has been developed and was tested on a variety of Mn complexes and superoxidized Mn catalase. This routine was also used to determine the oxidation state composition of the Mn in [Ba{sub 8}Na{sub 2}ClMn{sub 16}(OH){sub 8}(CO{sub 3}){sub 4}L{sub 8}] .53 H{sub 2}O (L=1,3-diamino-2-hydroxypropane-N,N,N`N`-tetraacetic acid). 27 refs., 6 figs.

  4. Investigation of Co nanoparticle formation using time-dependent and spatially-resolved X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zinoveva, S.

    2008-04-15

    A crucial step towards controlled synthesis of nanoparticles is the detailed understanding of the various chemical processes that take place during the synthesis. X-ray Absorption Spectroscopy (XAS) is especially suitable for elucidating the type and structure of the intermediate metal species. It is applicable to materials that have no long range order and provides information on both electronic and geometric structures. Here a comparative study is reported of the formation of cobalt nanoparticles via thermolysis of two organometallic precursors dicobalt octacarbonyl (DCO) and alkyne-bridged dicobalt hexacarbonyl (ADH) in the presence of aluminum organics. Using time-dependent XAS a reaction pathway different from both the atom based La Mer model and the Watzky and Finsky autocatalytic surface growth model is observed. Where prior to the nucleation several intermediates are formed and the initial nucleus is composed of Co atoms coordinated with ligands Co{sub n}(CO){sub m} with n=2-3, m=3-5. The formation of Co nanoparticles was also investigated using a reaction different from thermolysis of cobalt carbonyls, namely reduction of Co (II) acetate by sodium borohydrate. Here the combination of microreactor system and spatially resolved XAS allowed ''in situ'' monitoring of the wet chemical synthesis. Several steps of the reaction were spatially resolved in the microreactor. The vertical size of the X-ray beam (50 {mu}m) focused with Kirkpatrick-Baez mirror system, determines the time resolution (better than 2 ms). The results provide direct insight into rapid process of nanoparticles formation and demonstrate the potential of this new technique for the fundamental studies of such type of processes where miniaturization and timeresolution are important. Like in the carbonyls thermolysis no evidence for the reduction of the starting complex to isolated Co{sup 0} atoms followed by nucleation of Co{sup 0} atoms was observed. (orig.)

  5. Investigation of Co nanoparticle formation using time-dependent and spatially-resolved X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Zinoveva, S

    2008-04-15

    A crucial step towards controlled synthesis of nanoparticles is the detailed understanding of the various chemical processes that take place during the synthesis. X-ray Absorption Spectroscopy (XAS) is especially suitable for elucidating the type and structure of the intermediate metal species. It is applicable to materials that have no long range order and provides information on both electronic and geometric structures. Here a comparative study is reported of the formation of cobalt nanoparticles via thermolysis of two organometallic precursors dicobalt octacarbonyl (DCO) and alkyne-bridged dicobalt hexacarbonyl (ADH) in the presence of aluminum organics. Using time-dependent XAS a reaction pathway different from both the atom based La Mer model and the Watzky and Finsky autocatalytic surface growth model is observed. Where prior to the nucleation several intermediates are formed and the initial nucleus is composed of Co atoms coordinated with ligands Co{sub n}(CO){sub m} with n=2-3, m=3-5. The formation of Co nanoparticles was also investigated using a reaction different from thermolysis of cobalt carbonyls, namely reduction of Co (II) acetate by sodium borohydrate. Here the combination of microreactor system and spatially resolved XAS allowed ''in situ'' monitoring of the wet chemical synthesis. Several steps of the reaction were spatially resolved in the microreactor. The vertical size of the X-ray beam (50 {mu}m) focused with Kirkpatrick-Baez mirror system, determines the time resolution (better than 2 ms). The results provide direct insight into rapid process of nanoparticles formation and demonstrate the potential of this new technique for the fundamental studies of such type of processes where miniaturization and timeresolution are important. Like in the carbonyls thermolysis no evidence for the reduction of the starting complex to isolated Co{sup 0} atoms followed by nucleation of Co{sup 0} atoms was observed. (orig.)

  6. Structure and nature of the metal-support interface: characterization of iridium clusters on magnesium oxide by extended x-ray absorption fine structure spectroscopy

    NARCIS (Netherlands)

    Zon, van F.B.M.; Maloney, S.D.; Gates, B.C.; Koningsberger, D.C.

    1993-01-01

    X-ray absorption spectroscopy was used to characterize the metal-support interface in catalysts consisting of very small Ir clusters of nearly uniform nuclearity on the surface of MgO powder. [Ir4(CO)12] on MgO was converted in high yield into [HIr4(CO)11]- and sep. into [Ir6(CO)15]2-. EXAFS data

  7. An investigation of the chromium oxidation state of a monoanionic chromium tris(catecholate) complex by X-ray absorption and EPR spectroscopies

    DEFF Research Database (Denmark)

    Pattison, D I; Levina, A; Davies, Michael Jonathan

    2001-01-01

    The well-known monoanionic Cr tris(3,5-di-tert-butylcatecholato) complex, [Cr(DTBC)3]-, has been studied by X-ray absorption spectroscopy. The multiple-scattering fit to the XAFS gave good correlation (R = 19.8%) and good values for all of the bond lengths, angles, and Debye-Waller factors. The p...

  8. Reactor for tracking catalyst nanoparticles in liquid at high temperature under a high-pressure gas phase with X-ray absorption spectroscopy.

    Science.gov (United States)

    Nguyen, Luan; Tao, Franklin Feng

    2018-02-01

    Structure of catalyst nanoparticles dispersed in liquid phase at high temperature under gas phase of reactant(s) at higher pressure (≥5 bars) is important for fundamental understanding of catalytic reactions performed on these catalyst nanoparticles. Most structural characterizations of a catalyst performing catalysis in liquid at high temperature under gas phase at high pressure were performed in an ex situ condition in terms of characterizations before or after catalysis since, from technical point of view, access to the catalyst nanoparticles during catalysis in liquid phase at high temperature under high pressure reactant gas is challenging. Here we designed a reactor which allows us to perform structural characterization using X-ray absorption spectroscopy including X-ray absorption near edge structure spectroscopy and extended X-ray absorption fine structure spectroscopy to study catalyst nanoparticles under harsh catalysis conditions in terms of liquid up to 350 °C under gas phase with a pressure up to 50 bars. This reactor remains nanoparticles of a catalyst homogeneously dispersed in liquid during catalysis and X-ray absorption spectroscopy characterization.

  9. Molybdenum reduction in a sulfidic lake: Evidence from X-ray absorption fine-structure spectroscopy and implications for the Mo paleoproxy

    DEFF Research Database (Denmark)

    Dahl, T. W.; Chappaz, A.; Fitts, J. P.

    2013-01-01

    and the ultimate Mo host in euxinic sediments are not well understood. We used X-ray absorption fine structure (XAFS) spectroscopy to determine the oxidation state and the molecular coordination environment of pristine, solid phase Mo in sediments from permanently euxinic Lake Cadagno, Switzerland. Samples were...

  10. The effect of water on the stability of iron oxide and iron carbide nanoparticles in hydrogen and syngas followed by in situ X-ray absorption spectroscopy

    NARCIS (Netherlands)

    Thuene, P.C.; Moodley - Gengan, P.; Scheijen, F.J.E.; Fredriksson, H.O.A.; Lancee, R.J.; Kropf, J.; Miller, J.T.; Niemantsverdriet, J.W.

    2012-01-01

    The effect of water on iron-based nanoparticles under hydrogen and syngas was investigated by in situ X-ray absorption spectroscopy. The iron oxide (¿-Fe2O3) nanoparticles, dispersed as a monolayer on flat silica surfaces, were readily converted into metallic iron in dry hydrogen at 350 °C and into

  11. Nature of the metal-support interface in supported metal catalysts: results from x-ray absorption spectroscopy

    NARCIS (Netherlands)

    Koningsberger, D.C.; Gates, B.C.

    1992-01-01

    X-ray absorption spectra characterizing the metal-support interface in supported metal complexes and supported metal catalysts are summarized and evaluated with 29 refs. Mononuclear transition metal complexes on non-reducible metal oxide supports are bonded with metal-oxygen bonds of .apprx.2.15

  12. Phase transition in LiVO2 studied by near-edge x-ray-absorption spectroscopy

    NARCIS (Netherlands)

    Pen, HF; Tjeng, LH; Pellegrin, E; deGroot, FMF; Sawatzky, GA; vanVeenendaal, MA; Chen, CT

    1997-01-01

    We present temperature-dependent V-2p and O-1s x-ray-absorption spectra of LiVO2. The aim of this study is to monitor changes in electronic structure on going through the phase transition. The spectral changes turn out to be very small: the V-3d-O-2p hybridization does not change considerably, and

  13. Coelectrodeposition of Ternary Mn-Oxide/Polypyrrole Composites for ORR Electrocatalysts: A Study Based on Micro-X-ray Absorption Spectroscopy and X-ray Fluorescence Mapping

    Directory of Open Access Journals (Sweden)

    Benedetto Bozzini

    2015-08-01

    Full Text Available Low energy X-ray fluorescence (XRF and soft X-ray absorption (XAS microspectroscopies at high space-resolution are employed for the investigation of the coelectrodeposition of composites consisting of a polypyrrole(PPy-matrix and Mn-based ternary dispersoids, that have been proposed as promising electrocatalysts for oxygen-reduction electrodes. Specifically, we studied Mn–Co–Cu/PP, Mn–Co–Mg/PPy and Mn–Ni–Mg/PPy co-electrodeposits. The Mn–Co–Cu system features the best ORR electrocatalytic activity in terms of electron transfer number, onset potential, half-wave potential and current density. XRF maps and micro-XAS spectra yield compositional and chemical state distributions, contributing unique molecular-level information on the pulse-plating processes. Mn, Ni, Co and Mg exhibit a bimodal distribution consisting of mesoscopic aggregates of micrometric globuli, separated by polymer-rich ridges. Within this common qualitative scenario, the individual systems exhibit quantitatively different chemical distribution patterns, resulting from specific electrokinetic and electrosorption properties of the single components. The electrodeposits consist of Mn3+,4+-oxide particles, accompanied by combinations of Co0/Co2+, Ni0/Ni2+ and Cu0,+/Cu2+ resulting from the alternance of cathodic and anodic pulses. The formation of highly electroactive Mn3+,4+ in the as-fabricated material is a specific feature of the ternary systems, deriving from synergistic stabilisation brought about by two types of bivalent dopants as well as by galvanic contact to elemental metal; this result represents a considerable improvement in material quality with respect to previously studied Mn/PPy and Mn-based/PPy binaries.

  14. Mechanistic studies of chemical looping desulfurization of Mn-based oxides using in situ X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    König, C.F.J.; Nachtegaal, M.; Seemann, M.; Clemens, F.; Garderen, N. van; Biollaz, S.M.A.; Schildhauer, T.J.

    2014-01-01

    Highlights: • Mn sorbents remove H 2 S from hot syngas in chemical looping desulfurization process. • State of Mn followed by in situ X-ray absorption spectroscopy and mass spectrometry. • Two-step mechanism explains the formation of SO 2 under reducing conditions. - Abstract: Cleaning of producer gas from biomass gasification is required for further processing, e.g. to avoid catalyst poisoning in subsequent conversion steps. High-temperature gas cleaning, of which sulfur removal is an important part, is a promising way to improve the overall efficiency of biomass conversion. In a high temperature “chemical looping desulfurization” process, a sorbent material, here manganese oxide, is cycled between producer gas from the gasifier to remove sulfur species, and an oxidizing atmosphere, in which the sulfur species are released as SO 2 . Alternatively, the use of such material as reactive bed material could be integrated into an allothermal dual fluidized bed gasifier. In a laboratory reactor, we subjected manganese-based materials to a periodically changing gas atmosphere, simulating a “chemical looping desulfurization” reactor. The “fuel reactor” gas contained H 2 , CO, CH 4 and H 2 S, similar as in the producer gas, and the “oxidizing reactor” contained diluted O 2 . Mass spectrometry showed that most of the H 2 S is taken up by the sample in the “fuel reactor” part, while also some unwanted SO 2 is generated in the “fuel reactor” part. Most of the sulfur is released in the oxidizing reactor. Simultaneous in situ X-ray absorption spectroscopy (XAS) of the Mn materials during different stages of the chemical looping desulfurization process showed that the initial Mn 3 O 4 is transformed in the presence of H 2 S to MnS via a MnO intermediate in the fuel reactor. Oxygen from the reduction of Mn 3 O 4 oxidizes some H 2 S to the undesired SO 2 in the fuel reactor. Upon exposure to O 2 , MnS is again oxidized to Mn 3 O 4 via MnO, releasing SO

  15. X-ray absorption spectroscopy of diluted system by undulator photon source and multi-element solid-state detector

    CERN Document Server

    Tanida, H

    2001-01-01

    In order to measure the extended X-ray absorption fine structure (EXAFS) spectrum of an ultra-diluted system, an optics and detector control system for a synchrotron radiation beamline is developed. The undulator gap width is continuously tuned to obtain the maximum X-ray photon flux during the energy scan for the EXAFS measurement. A piezoelectric translator optimizes the parallelism of the double crystal in a monochromator at each measurement point to compensate for mechanical errors of the monochromator, resulting in a smooth and intense X-ray photon flux during the measurement. For a detection of a weak fluorescence signal from diluted samples, a 19-element solid-state detector and digital signal processor are used. A K-edge EXAFS spectrum of iron in a myoglobin aqueous solution with a concentration of 5.58 parts per million was obtained by this system.

  16. Electronic structure of barium strontium titanate by soft-x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Uehara, Y.; Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C.

    1997-01-01

    Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the electronic structure of the material. Studies of the electronic structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the electronic structure of these two materials. In this report, the authors present the Ti L 2,3 absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features

  17. Electronic structure of barium strontium titanate by soft-x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Uehara, Y. [Mitsubishi Electric Co., Hyogo (Japan); Underwood, J.H.; Gullikson, E.M.; Perera, R.C.C. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)

    1997-04-01

    Perovskite-type titanates, such as Strontium Titanate (STO), Barium Titanate (BTO), and Lead Titanate (PTO) have been widely studied because they show good electric and optical properties. In recent years, thin films of Barium Strontium Titanate (BST) have been paid much attention as dielectrics of dynamic random access memory (DRAM) capacitors. BST is a better insulator with a higher dielectric constant than STO and can be controlled in a paraelectric phase with an appropriate ratio of Ba/Sr composition, however, few studies have been done on the electronic structure of the material. Studies of the electronic structure of such materials can be beneficial, both for fundamental physics research and for improving technological applications. BTO is a famous ferroelectric material with a tetragonal structure, in which Ti and Ba atoms are slightly displaced from the lattice points. On the other hand, BST keeps a paraelectric phase, which means that the atoms are still at the cubic lattice points. It should be of great interest to see how this difference of the local structure around Ti atoms between BTO and BST effects the electronic structure of these two materials. In this report, the authors present the Ti L{sub 2,3} absorption spectra of STO, BTO, and BST measured with very high accuracy in energy of the absorption features.

  18. X-ray absorption spectroscopy of aluminum z-pinch plasma with tungsten backlighter planar wire array source

    Energy Technology Data Exchange (ETDEWEB)

    Osborne, G. C.; Kantsyrev, V. L.; Safronova, A. S.; Esaulov, A. A.; Weller, M. E.; Shrestha, I.; Shlyaptseva, V. V. [Physics Department, University of Nevada, Reno, Reno, Nevada 89557 (United States); Ouart, N. D. [Naval Research Laboratory, Washington, D.C. 20375 (United States)

    2012-10-15

    Absorption features from K-shell aluminum z-pinch plasmas have recently been studied on Zebra, the 1.7 MA pulse power generator at the Nevada Terawatt Facility. In particular, tungsten plasma has been used as a semi-backlighter source in the generation of aluminum K-shell absorption spectra by placing a single Al wire at or near the end of a single planar W array. All spectroscopic experimental results were recorded using a time-integrated, spatially resolved convex potassium hydrogen phthalate (KAP) crystal spectrometer. Other diagnostics used to study these plasmas included x-ray detectors, optical imaging, laser shadowgraphy, and time-gated and time-integrated x-ray pinhole imagers. Through comparisons with previous publications, Al K-shell absorption lines are shown to be from much lower electron temperature ({approx}10-40 eV) plasmas than emission spectra ({approx}350-500 eV).

  19. Adsorption of uranium(VI) to manganese oxides: X-ray absorption spectroscopy and surface complexation modeling.

    Science.gov (United States)

    Wang, Zimeng; Lee, Sung-Woo; Catalano, Jeffrey G; Lezama-Pacheco, Juan S; Bargar, John R; Tebo, Bradley M; Giammar, Daniel E

    2013-01-15

    The mobility of hexavalent uranium in soil and groundwater is strongly governed by adsorption to mineral surfaces. As strong naturally occurring adsorbents, manganese oxides may significantly influence the fate and transport of uranium. Models for U(VI) adsorption over a broad range of chemical conditions can improve predictive capabilities for uranium transport in the subsurface. This study integrated batch experiments of U(VI) adsorption to synthetic and biogenic MnO(2), surface complexation modeling, ζ-potential analysis, and molecular-scale characterization of adsorbed U(VI) with extended X-ray absorption fine structure (EXAFS) spectroscopy. The surface complexation model included inner-sphere monodentate and bidentate surface complexes and a ternary uranyl-carbonato surface complex, which was consistent with the EXAFS analysis. The model could successfully simulate adsorption results over a broad range of pH and dissolved inorganic carbon concentrations. U(VI) adsorption to synthetic δ-MnO(2) appears to be stronger than to biogenic MnO(2), and the differences in adsorption affinity and capacity are not associated with any substantial difference in U(VI) coordination.

  20. Solvation structure determination of nickel(II) ion in six nitriles using extended X-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Inada, Yasuhiro; Funahashi, Shigenobu

    1997-01-01

    The solvation structures of the nickel(II) ion in six nitriles have been determined using X-ray absorption fine structure spectroscopy. The coordination number and the Ni-N bond length are 6 and 206.9 ± 0.6 pm in acetonitrile, 5.9 ± 0.2 and 206.9 ± 0.6 pm in propionitrile, 6.0 ± 0.2 and 206.8 ± 0.6 pm in butyronitrile, 6.0 ± 0.2 and 206.8 ± 0.6 pm in isobutyronitrile, 6.0 ± 0.2 and 206.8 ± 0.6 pm in valeronitrile, and 6.0 ± 0.2 and 206.5 ± 0.7 pm in benzonitrile, respectively. The structure parameters around the nickel(II) ion in all the nitriles are not affected by the bulkiness of the nitrile molecules. On the basis of the obtained structure parameters, we have discussed the structural characteristics around the nickel(II) ion with nitrogen and oxygen donor solvents and the reaction mechanisms for nitrile exchange on the nickel(II) ion. (author)

  1. Metal induced crystallization of amorphous silicon thin films studied by x-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Naidu, K Lakshun; Mohiddon, Md Ahamad; Dalba, G; Krishna, M Ghanashyam; Rocca, F

    2013-01-01

    The role of thin metallic layer (Chromium or Nickel) in the crystallization of a-Si film has been studied using X-ray absorption fine structure spectroscopy (XAFS). The films were grown at different substrate temperatures in two different geometrical structures : (a) a 200 nm metal layer (Cr or Ni) was deposited on fused silica (FS) followed by 400 nm of a-Si and (b) the 400 nm a-Si layer was deposited on FS followed by 200 nm of metal layer. XAFS measurements at Cr K-edge and Ni K-edge were done at BM08 – GILDA beamline of the European Synchrotron Research Facility (ESRF, Grenoble, F) in fluorescence mode. To understand the evolution of the local structure of Cr/Ni diffusing from bottom to top and from top to bottom, total reflection and higher incidence angles were employed. The relative content of metal, metal oxide and metal silicides compounds on the upper surface and/or in the bulk of different films has been evaluated as a function of thermal treatment.

  2. Localized holes and delocalized electrons in photoexcited inorganic perovskites: Watching each atomic actor by picosecond X-ray absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    Fabio G. Santomauro

    2017-07-01

    Full Text Available We report on an element-selective study of the fate of charge carriers in photoexcited inorganic CsPbBr3 and CsPb(ClBr3 perovskite nanocrystals in toluene solutions using time-resolved X-ray absorption spectroscopy with 80 ps time resolution. Probing the Br K-edge, the Pb L3-edge, and the Cs L2-edge, we find that holes in the valence band are localized at Br atoms, forming small polarons, while electrons appear as delocalized in the conduction band. No signature of either electronic or structural changes is observed at the Cs L2-edge. The results at the Br and Pb edges suggest the existence of a weakly localized exciton, while the absence of signatures at the Cs edge indicates that the Cs+ cation plays no role in the charge transport, at least beyond 80 ps. This first, time-resolved element-specific study of perovskites helps understand the rather modest charge carrier mobilities in these materials.

  3. High-resolution molybdenum K-edge X-ray absorption spectroscopy analyzed with time-dependent density functional theory.

    Science.gov (United States)

    Lima, Frederico A; Bjornsson, Ragnar; Weyhermüller, Thomas; Chandrasekaran, Perumalreddy; Glatzel, Pieter; Neese, Frank; DeBeer, Serena

    2013-12-28

    X-ray absorption spectroscopy (XAS) is a widely used experimental technique capable of selectively probing the local structure around an absorbing atomic species in molecules and materials. When applied to heavy elements, however, the quantitative interpretation can be challenging due to the intrinsic spectral broadening arising from the decrease in the core-hole lifetime. In this work we have used high-energy resolution fluorescence detected XAS (HERFD-XAS) to investigate a series of molybdenum complexes. The sharper spectral features obtained by HERFD-XAS measurements enable a clear assignment of the features present in the pre-edge region. Time-dependent density functional theory (TDDFT) has been previously shown to predict K-pre-edge XAS spectra of first row transition metal compounds with a reasonable degree of accuracy. Here we extend this approach to molybdenum K-edge HERFD-XAS and present the necessary calibration. Modern pure and hybrid functionals are utilized and relativistic effects are accounted for using either the Zeroth Order Regular Approximation (ZORA) or the second order Douglas-Kroll-Hess (DKH2) scalar relativistic approximations. We have found that both the predicted energies and intensities are in excellent agreement with experiment, independent of the functional used. The model chosen to account for relativistic effects also has little impact on the calculated spectra. This study provides an important calibration set for future applications of molybdenum HERFD-XAS to complex catalytic systems.

  4. X-ray absorption holography

    Czech Academy of Sciences Publication Activity Database

    Kopecký, Miloš; Lausi, A.; Bussetto, E.; Kub, Jiří; Savoia, A.

    2002-01-01

    Roč. 88, č. 18 (2002), s. 185503-1 - 185503-3 ISSN 0031-9007 R&D Projects: GA MŠk LN00A100 Institutional research plan: CEZ:AV0Z1010921 Keywords : x-ray holography Subject RIV: BH - Optics, Masers, Lasers Impact factor: 7.323, year: 2002

  5. Electrosynthesis of ZnO nanorods and nanotowers: Morphology and X-ray Absorption Near Edge Spectroscopy studies

    Energy Technology Data Exchange (ETDEWEB)

    Sigircik, Gokmen, E-mail: gsigircik@cu.edu.tr [Chemistry Department, University of Cukurova, 01330 Adana (Turkey); Erken, Ozge [Department of Physics, Faculty Science and Letters, Adiyaman University, 02040 Adiyaman (Turkey); Tuken, Tunc [Chemistry Department, University of Cukurova, 01330 Adana (Turkey); Gumus, Cebrail [Physics Department, University of Cukurova, 01330 Adana (Turkey); Ozkendir, Osman M. [Department of Energy Systems Engineering Tarsus Technology Faculty, Mersin University, 33400 Tarsus (Turkey); Ufuktepe, Yuksel [Physics Department, University of Cukurova, 01330 Adana (Turkey)

    2015-06-15

    Highlights: • Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. • Uniform and well-defined ZnO nano-towers and rods have been obtained via electrochemical deposition. • The presence of chloride ions altered the nucleation rate of ZnO particles on ITO substrates and resulting crystallographic properties. • Comparing the rod and tower nano-structured ZnO thin films, the excitation behavior of valance band electrons is different. - Abstract: Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. The resulting opto-electronic properties were interpreted extensively, using X-ray diffraction (XRD), X-ray Absorption Near Edge Spectroscopy (XANES), field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy and four probe techniques. The ZnO deposition is mass transport controlled process and the interaction of chloride ions with the surface has great influence on diffusion kinetics, considering the substantial species (Zn{sup 2+} and OH{sup −}) involved in the construction of ZnO film. This effect does not change major lattice parameters, as shown with detailed analysis of XRD data. However, the texture coefficient (T{sub c}) (0 0 2) value is higher in presence of chloride ions containing synthesis solution which gave vertically aligned, well defined and uniformly dispersed nanorods structure. The calculated E{sub g} values are in the range 3.28–3.41 eV and 3.22–3.31 eV for ZnO nanorods and nanotowers synthesized at different deposition periods, respectively. Furthermore, the charge mobility values regarding the deposition periods were measured to be in the ranges from 130.4 to 449.2 cm{sup 2} V{sup −1} s{sup −1} and 126.2 to 204.7 cm{sup 2} V{sup −1} s{sup −1} for nanorods and nanotowers, respectively. From XANES results, it was shown that the Zn K

  6. Electrosynthesis of ZnO nanorods and nanotowers: Morphology and X-ray Absorption Near Edge Spectroscopy studies

    International Nuclear Information System (INIS)

    Sigircik, Gokmen; Erken, Ozge; Tuken, Tunc; Gumus, Cebrail; Ozkendir, Osman M.; Ufuktepe, Yuksel

    2015-01-01

    Highlights: • Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. • Uniform and well-defined ZnO nano-towers and rods have been obtained via electrochemical deposition. • The presence of chloride ions altered the nucleation rate of ZnO particles on ITO substrates and resulting crystallographic properties. • Comparing the rod and tower nano-structured ZnO thin films, the excitation behavior of valance band electrons is different. - Abstract: Deposition mechanism of nano-structured ZnO films has been investigated in the absence and presence of chloride ions from aqueous solution. The resulting opto-electronic properties were interpreted extensively, using X-ray diffraction (XRD), X-ray Absorption Near Edge Spectroscopy (XANES), field emission scanning electron microscopy (FE-SEM), UV-Visible spectroscopy and four probe techniques. The ZnO deposition is mass transport controlled process and the interaction of chloride ions with the surface has great influence on diffusion kinetics, considering the substantial species (Zn 2+ and OH − ) involved in the construction of ZnO film. This effect does not change major lattice parameters, as shown with detailed analysis of XRD data. However, the texture coefficient (T c ) (0 0 2) value is higher in presence of chloride ions containing synthesis solution which gave vertically aligned, well defined and uniformly dispersed nanorods structure. The calculated E g values are in the range 3.28–3.41 eV and 3.22–3.31 eV for ZnO nanorods and nanotowers synthesized at different deposition periods, respectively. Furthermore, the charge mobility values regarding the deposition periods were measured to be in the ranges from 130.4 to 449.2 cm 2 V −1 s −1 and 126.2 to 204.7 cm 2 V −1 s −1 for nanorods and nanotowers, respectively. From XANES results, it was shown that the Zn K-edge spectrum is dominated by the transition of Zn 1s core

  7. A study of the reactivity of elemental Cr/Se/Te thin multilayers using X-ray reflectometry, in situ X-ray diffraction and X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Behrens, Malte; Tomforde, Jan; May, Enno; Kiebach, Ragnar; Bensch, Wolfgang; Haeussler, Dietrich; Jaeger, Wolfgang

    2006-01-01

    The reactivity of [Cr/Se/Te] multilayers under annealing was investigated using X-ray reflectometry, in situ X-ray diffraction, X-ray absorption fine structure (XAFS) measurements and transmission electron microscopy. For all samples, interdiffusion was complete at temperatures between 100 and 300 deg. C, depending on the repeating tri-layer thickness. A crystalline phase nucleated approximately 20 deg. C above the temperature where interdiffusion was finished. The first crystalline phase in a binary Cr/Te sample was layered CrTe 3 nucleating at 230 deg. C. In ternary samples (Se:Te=0.6-1.2), the low-temperature nucleation of such a layered CrQ 3 (Q=Se, Te) phase is suppressed and instead the phase Cr 2 Q 3 nucleates first. Interestingly, this phase decomposes around 500 deg. C into layered CrQ 3 . In contrast, binary Cr/Se samples form stable amorphous alloys after interdiffusion and Cr 3 Se 4 nucleates around 500 deg. C as the only crystalline phase. Evaluation of the XAFS data of annealed samples yield Se-Cr distances of 2.568(1) and 2.552(1) A for Cr 2 Q 3 and CrQ 3 , respectively. In the latter sample, higher coordination shells around Se are seen accounting for the Se-Te contacts in the structure. - Graphical abstract: The first step of the reaction of elemental Cr/Te/Se-multilayers is the interdiffusion of the elements as evidenced by the decay of the modulation peaks in the low-angle region of the X-ray diffraction patterns. The subsequent growth of Bragg peaks at higher scattering angles indicates crystallization of chromium chalcogenide Cr 2 Te 3- x Se x

  8. Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Sayers, D.E.

    1989-01-01

    At the time of the submission of the original proposal more than 7 years ago, the X-11 PRT had set as a goal to develop one of the leading and most comprehensive x-ray absorption beam lines in the world. By any measure we have been successful. As is well documented in previous annual progress report and in the NSLS annual reports, our PRT has been extremely productive in a wide range of topics in materials science, solid state physics, chemistry and biology. Well over 100 papers have been published acknowledging the support of this contract and this continues at a rate of about 30 papers per year and about 20 invited presentations per year. Significant in this report are major studies in high T c compounds, advances in interface studies, new results in premelting phenomena, several pioneering studies in application of XAS to electrochemistry and significant progress in our understanding of the structure of amorphous chalcogenide systems and their photostructural changes

  9. New methods and applications in time-resolved X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Stoetzel, Jan Eric

    2012-07-01

    Recent experimental advances and developments in the QEXAFS technique were presented along with new applications in the disciplines of catalysis and surface science. Both performance and user-friendliness of the QEXAFS method were significantly improved, while the applicability of QEXAFS was extended by newly designed mechanics. The application of a fast angular encoder proved to be capable to sample the continuously changing Bragg angle of the monochromator crystal synchronized to the acquired absorption data. A new data acquisition system was designed, based on a multifunctional ADC board, which provides high acquisition frequencies, while low noise acquisition could be achieved due to the provided differential acquisition mode. Additionally, control of all experimental devices as current amplifiers, monochromator motors and sample stages were implemented to further increase the efficiency of the experimental setup for QEFAS measurements. In order to simplify the processing of the huge generated QEXAFS raw data files, a completely new software tool for data analysis was designed, which provides not only the basic procedures of QEXAFS data analysis, but also many approaches customized for time-resolved data. Apart from technical advances, various experiments were performed with QEXAFS to gain new insights into the complex processes of several catalytic reactions, the thermal decomposition of metal oxalates, as well as layer growth processes and reactions on rough surfaces. Supported Pd catalysts were investigated during catalytic partial oxidation of methane, whereby oscillations in the conversion were linked to structural changes of the catalyst. Kinetic oscillations were also investigated on a supported Pt catalyst during the extinction of CO oxidation induced by decreasing temperature. Modulated experiments were investigated (i) on supported Pt-Rh/Al{sub 2}O{sub 3} catalysts during active catalytic partial oxidation in switching gas atmospheres of methane and

  10. Quantitative probe of the transition metal redox in battery electrodes through soft x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Li, Qinghao; Chen, Jun; Chen, Yanxue; Yan, Shishen; Qiao, Ruimin; Zhuo, Zengqing; Hussain, Zahid; Yang, Wanli; Wray, L Andrew; Pan, Feng

    2016-01-01

    Most battery positive electrodes operate with a 3 d transition-metal (TM) reaction centre. A direct and quantitative probe of the TM states upon electrochemical cycling is valuable for understanding the detailed cycling mechanism and charge diffusion in the electrodes, which is related with many practical parameters of a battery. This review includes a comprehensive summary of our recent demonstrations of five different types of quantitative analysis of the TM states in battery electrodes based on soft x-ray absorption spectroscopy and multiplet calculations. In LiFePO 4 , a system of a well-known two-phase transformation type, the TM redox could be strictly determined through a simple linear combination of the two end-members. In Mn-based compounds, the Mn states could also be quantitatively evaluated, but a set of reference spectra with all the three possible Mn valences needs to be deliberately selected and considered in the fitting. Although the fluorescence signals suffer the self-absorption distortion, the multiplet calculations could consider the distortion effect, which allows a quantitative determination of the overall Ni oxidation state in the bulk. With the aid of multiplet calculations, one could also achieve a quasi-quantitative analysis of the Co redox evolution in LiCoO 2 based on the energy position of the spectroscopic peak. The benefit of multiplet calculations is more important for studying electrode materials with TMs of mixed spin states, as exemplified by the quantitative analysis of the mixed spin Na 2−x Fe 2 (CN) 6 system. At the end, we showcase that such quantitative analysis could provide valuable information for optimizing the electrochemical performance of Na 0.44 MnO 2 electrodes for Na-ion batteries. The methodology summarized in this review could be extended to other energy application systems with TM redox centre for detailed analysis, for example, fuel cell and catalytic materials. (topical review)

  11. Quantitative probe of the transition metal redox in battery electrodes through soft x-ray absorption spectroscopy

    Science.gov (United States)

    Li, Qinghao; Qiao, Ruimin; Wray, L. Andrew; Chen, Jun; Zhuo, Zengqing; Chen, Yanxue; Yan, Shishen; Pan, Feng; Hussain, Zahid; Yang, Wanli

    2016-10-01

    Most battery positive electrodes operate with a 3d transition-metal (TM) reaction centre. A direct and quantitative probe of the TM states upon electrochemical cycling is valuable for understanding the detailed cycling mechanism and charge diffusion in the electrodes, which is related with many practical parameters of a battery. This review includes a comprehensive summary of our recent demonstrations of five different types of quantitative analysis of the TM states in battery electrodes based on soft x-ray absorption spectroscopy and multiplet calculations. In LiFePO4, a system of a well-known two-phase transformation type, the TM redox could be strictly determined through a simple linear combination of the two end-members. In Mn-based compounds, the Mn states could also be quantitatively evaluated, but a set of reference spectra with all the three possible Mn valences needs to be deliberately selected and considered in the fitting. Although the fluorescence signals suffer the self-absorption distortion, the multiplet calculations could consider the distortion effect, which allows a quantitative determination of the overall Ni oxidation state in the bulk. With the aid of multiplet calculations, one could also achieve a quasi-quantitative analysis of the Co redox evolution in LiCoO2 based on the energy position of the spectroscopic peak. The benefit of multiplet calculations is more important for studying electrode materials with TMs of mixed spin states, as exemplified by the quantitative analysis of the mixed spin Na2-x Fe2(CN)6 system. At the end, we showcase that such quantitative analysis could provide valuable information for optimizing the electrochemical performance of Na0.44MnO2 electrodes for Na-ion batteries. The methodology summarized in this review could be extended to other energy application systems with TM redox centre for detailed analysis, for example, fuel cell and catalytic materials.

  12. X-ray absorption spectroscopy of ultramarine pigments: A new analytical method for the polysulfide radical anion S3- chromophore

    International Nuclear Information System (INIS)

    Fleet, Michael E.; Liu, Xi

    2010-01-01

    Blue and mauve ultramarine artists' pigments and their heat-treated products have been investigated by sulfur K-edge X-ray absorption. X-ray absorption near-edge structure spectra are dominated by features of reduced sulfur and sulfate species. There is also a pre-peak at about 2468.0 eV which reflects the presence of the unpaired electron on the polysulfide radical anion (S 3 - ). Pre-peak intensity is directly proportional to the depth of blue coloration, and provides a new, independent method for estimating the proportion of ultramarine cage sites occupied by the blue chromophore. The occupancy of the polysulfide radical anion S 3 - is estimated to be 33% in an intense ultramarine blue pigment, 22% in a dark blue ultramarine pigment, and 1% in deep royal blue lazurite from Afghanistan. The more efficient development of color in lazurite is attributed to extensive annealing of the mineral structure in the natural environment.

  13. Fast Time-Dependent Density Functional Theory Calculations of the X-ray Absorption Spectroscopy of Large Systems.

    Science.gov (United States)

    Besley, Nicholas A

    2016-10-11

    The computational cost of calculations of K-edge X-ray absorption spectra using time-dependent density functional (TDDFT) within the Tamm-Dancoff approximation is significantly reduced through the introduction of a severe integral screening procedure that includes only integrals that involve the core s basis function of the absorbing atom(s) coupled with a reduced quality numerical quadrature for integrals associated with the exchange and correlation functionals. The memory required for the calculations is reduced through construction of the TDDFT matrix within the absorbing core orbitals excitation space and exploiting further truncation of the virtual orbital space. The resulting method, denoted fTDDFTs, leads to much faster calculations and makes the study of large systems tractable. The capability of the method is demonstrated through calculations of the X-ray absorption spectra at the carbon K-edge of chlorophyll a, C 60 and C 70 .

  14. X-Ray Absorption with Transmission X-Ray Microscopes

    NARCIS (Netherlands)

    de Groot, F.M.F.

    2016-01-01

    In this section we focus on the use of transmission X-ray microscopy (TXM) to measure the XAS spectra. In the last decade a range of soft X-ray and hard X-ray TXM microscopes have been developed, allowing the measurement of XAS spectra with 10–100 nm resolution. In the hard X-ray range the TXM

  15. Study of the L2,3 edges of 3d transition metals by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Akguel, G.; Aksoy, F.; Bozduman, A.; Ozkendir, O.M.; Ufuktepe, Y.; Luening, J.

    2008-01-01

    In the soft X-rays energy region, near edge X-ray absorption fine structure (NEXAFS) spectra are generally recorded by monitoring yield signals of secondary particles. These secondary particles, electrons or fluorescence photons, follow from the decay of the core hole excited in the primary absorption process. In general the yield signals are, to a good approximation, proportional to the absorption coefficient. However, in several applications it would be desirable to measure the absorption coefficient quantitatively. To derive the absorption coefficient quantitatively from a yield spectrum, one needs to know the escape depth of the emitted electrons (λ e ) of the applied yield technique in the material of interest. Since this quantity is difficult to calculate, it is unknown for most materials. In this paper we present the first results of our systematic investigation of the total electron-yield (TEY) escape depth of the 3d transition metals (Fe, Co and Cu). In addition our results gave important information on the variation of the TEY escape depth with the filling of the 3d band

  16. Study of the L2,3 Edges of 3d Transition Metals By X-Ray Absorption Spectroscopy

    International Nuclear Information System (INIS)

    Akgul, G.; Aksoy, F.; Bozduman, A.; Ozkendir, O.M.; Ufuktepe, Y.; Luning, J.

    2008-01-01

    In the soft X-rays energy region, near edge X-ray absorption fine structure (NEXAFS) spectra are generally recorded by monitoring yield signals of secondary particles. These secondary particles, electrons or fluorescence photons, follow from the decay of the core hole excited in the primary absorption process. In general the yield signals are, to a good approximation, proportional to the absorption coefficient. However, in several applications it would be desirable to measure the absorption coefficient quantitatively. To derive the absorption coefficient quantitatively from a yield spectrum, one needs to know the escape depth of the emitted electrons (λ e ) of the applied yield technique in the material of interest. Since this quantity is difficult to calculate, it is unknown for most materials. In this paper we present the first results of our systematic investigation of the total electron-yield (TEY) escape depth of the 3d transition metals (Fe, Co and Cu). In addition our results gave important information on the variation of the TEY escape depth with the filling of the 3d band.

  17. Ultraviolet magnetic circular dichroism study and x-ray absorption spectroscopy of zinc-blende type CrAs multilayer

    International Nuclear Information System (INIS)

    Mizuguchi, M.; Manago, T.; Akinaga, H.; Yamada, T.; Yagi-Watanabe, K.; Yuri, M.; Chen, C.T.; Shirai, M.

    2004-01-01

    Full text: Half-metallic ferromagnets such as CrO 2 and Heusler alloys have attracted a great deal of attention due to its application to spin-dependent device. We have predicted by first principle calculations that zinc-blende (zb) type CrAs, which normally exists in a MnP type, shows a half-metallic band structure, and succeeded in fabrication of this film. However, the epitaxial growth with maintaining a zb structure was limited up to around the nominal thickness of 3 nm. In this contribution, ultraviolet magnetic circular dichroism (MCD) and x-ray absorption spectroscopy (XAS) of CrAs multilayers are reported. These multilayers include zb-CrAs layers and low-temperature GaAs layers stacked alternately, and total thicknesses of zb- CrAs are thicker than 3 nm. Incident beam with the photon energy from 4 to 8 eV were used, and samples were attached on a magnet with the magnetic field of 1.0 T for the MCD measurements. Strong signal with the peak top at 6.5 eV is observed in the MCD spectrum. It can be seen that the experimental spectrum has a good agreement with the theoretical one, which indicates the formation of a superstructure as designed. It was also clarified by the XAS measurement using incident beam from 560 to 600 eV that peak positions of these multilayers shift systematically according to the thickness of each layer. The CrAs/GaAs multilayer is also expected to possess a half-metallic property by the theoretical calculation, therefore, the present result shows the multilayer will be the promising candidate as the spin electronics material

  18. X-ray photoelectron spectroscopy study of pyrolytically coated graphite platforms submitted to simulated electrothermal atomic absorption spectrometry conditions

    International Nuclear Information System (INIS)

    Ruiz, Frine; Benzo, Zully; Quintal, Manuelita; Garaboto, Angel; Albornoz, Alberto; Brito, Joaquin L.

    2006-01-01

    The present work is part of an ongoing project aiming to a better understanding of the mechanisms of atomization on graphite furnace platforms used for electrothermal atomic absorption spectrometry (ETAAS). It reports the study of unused pyrolytic graphite coated platforms of commercial origin, as well as platforms thermally or thermo-chemically treated under simulated ETAAS analysis conditions. X-ray photoelectron spectroscopy (XPS) was employed to study the elements present at the surfaces of the platforms. New, unused platforms showed the presence of molybdenum, of unknown origin, in concentrations up to 1 at.%. Species in two different oxidations states (Mo 6+ and Mo 2+ ) were detected by analyzing the Mo 3d spectral region with high resolution XPS. The analysis of the C 1s region demonstrated the presence of several signals, one of these at 283.3 eV related to the presence of Mo carbide. The O 1s region showed also various peaks, including a signal that can be attributed to the presence of MoO 3 . Some carbon and oxygen signals were consistent with the presence of C=O and C-O- (probably C-OH) groups on the platforms surfaces. Upon thermal treatment up to 2900 deg. C, the intensity of the Mo signal decreased, but peaks due to Mo oxides (Mo 6+ and Mo 5+ ) and carbide (Mo 2+ ) were still apparent. Thermo-chemical treatment with 3 vol.% HCl solutions and heating up to 2900 deg. C resulted in further diminution of the Mo signal, with complete disappearance of Mo carbide species. Depth profiling of unused platforms by Ar + ion etching at increasing time periods demonstrated that, upon removal of several layers of carbonaceous material, the Mo signal disappears suggesting that this contamination is present only at the surface of the pyrolytic graphite platform

  19. Dissimilar behavior of technetium and rhenium in borosilicatewaste glass as determined by X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lukens, Wayne W.; McKeown, David A.; Buechele, Andrew C.; Muller,Isabelle S.; Shuh, David K.; Pegg, Ian L.

    2006-11-09

    Technetium-99 is an abundant, long-lived (t1/2 = 213,000 yr)fission product that creates challenges for the safe, long-term disposalof nuclear waste. While 99Tc receives attention largely due to its highenvironmental mobility, it also causes problems during its incorporationinto nuclear waste glass due to the volatility of Tc(VII) compounds. Thisvolatility decreases the amount of 99Tc stabilized in the waste glass andcauses contamination of the waste glass melter and off-gas system. Theapproach to decrease the volatility of 99Tc that has received the mostattention is reduction of the volatile Tc(VII) species to less volatileTc(IV) species in the glass melt. On engineering scale experiments,rhenium is often used as a non-radioactive surrogate for 99Tc to avoidthe radioactive contamination problems caused by volatile 99Tc compounds.However, Re(VII) is more stable towards reduction than Tc(VII), so morereducing conditions would be required in the glass melt to produceRe(IV). To better understand the redox behavior of Tc and Re in nuclearwaste glass, a series of glasses were prepared under different redoxconditions. The speciation of Tc and Re in the resulting glasses wasdetermined by X-ray absorption fine structure spectroscopy. Surprisingly,Re and Tc do not behave similarly in the glass melt. Although Tc(0),Tc(IV), and Tc(VII) were observed in these samples, only Re(0) andRe(VII) were found. In no case was Re(IV) (or Re(VI))observed.

  20. Element Specific Versus Integral Structural and Magnetic Properties of Co:ZnO and Gd:GaN Probed with Hard X-ray Absorption Spectroscopy

    Directory of Open Access Journals (Sweden)

    Andreas Ney

    2010-06-01

    Full Text Available Dilute magnetic semiconductors (DMS are envisioned as sources of spin-polarized carriers for future semiconductor devices which simultaneously utilize spin and charge of the carriers. The hope of discovering a DMS with ferromagnetic order up to room temperature still motivates research on suitable DMS materials. Two candidate wide-band gap DMS are Gd:GaN and Co:ZnO. We have used hard X-ray absorption spectroscopy (XAS and in particular X-ray linear dichroism (XLD and X-ray magnetic circular dichroism (XMCD to study both DMS materials with element specificity and compare these findings with results from integral SQUID magnetometry as well as electron paramagnetic resonance (EPR.

  1. X-ray absorption in atomic potassium

    International Nuclear Information System (INIS)

    Gomilsek, Jana Padeznik; Kodre, Alojz; Arcon, Iztok; Nemanic, Vincenc

    2008-01-01

    A new high-temperature absorption cell for potassium vapor is described. X-ray absorption coefficient of atomic potassium is determined in the energy interval of 600 eV above the K edge where thresholds for simultaneous excitations of 1s and outer electrons, down to [1s2p] excitation, appear. The result represents also the atomic absorption background for XAFS (X-ray absorption fine structure) structure analysis. The K ionization energy in the potassium vapor is determined and compared with theoretical data and with the value for the metal

  2. Molecular speciation of phosphorus in organic amendments and amended soils using nuclear magnetic resonance and X-ray absorption spectroscopies

    International Nuclear Information System (INIS)

    Ajibove, B.

    2007-01-01

    Characterization of phosphorus (P) in organic amendments is essential for environmentally sustainable fertilization of agricultural soils. The sequential chemical extraction (SCE) technique commonly used for P characterization does not provide any direct molecular information about P species. Studies were conducted to characterize P species in organic amendments and amended soils at a molecular level. The SCE was used to fractionate P in organic amendments including biosolids, hog, dairy and beef cattle manures, and poultry litter. The extracts were analyzed for total P and P species using inductively coupled plasma - optical emission spectroscopy (ICP-OES) and solution 31 P nuclear magnetic resonance (NMR) spectroscopy, respectively. The relative proportions of P species in intact organic amendments and residues after each extraction, and calcareous soils amended with organic amendments and monoammonium phosphate (MAP) were estimated using the synchrotron-based P 1s X-ray absorption near edge structure (XANES) spectroscopy. The solution 31 P NMR provided a detailed characterization of organic P in the non-labile NaOH and HCl fractions of organic amendments, but was limited in characterizing the labile fractions of most of these organic amendments due to their proneness to alkaline hydrolysis. The XANES analysis, however, identified the actual chemical species constituting the labile P that was only characterized as inorganic P or orthophosphates by sequential extraction and solution 31 P NMR. In the amended Vertisolic and Chernozemic soils, XANES analysis estimated 'soluble and adsorbed P' as the dominant P species. For the Vertisolic soil, both the unamended and soil amended with biosolids and MAP contained hydroxyapatite (HAP). In addition, soil amended with biosolids, hog and dairy manures contained β-tricalcium phosphate (TRICAL), a more soluble CaP than HAP. TRICAL was found in all amended soils except in that amended with hog manure, while HAP was present

  3. In situ observation of Cu-Ni alloy nanoparticle formation by X-ray diffraction, X-ray absorption spectroscopy, and transmission electron microscopy: Influence of Cu/Ni ratio

    DEFF Research Database (Denmark)

    Wu, Qiongxiao; Duchstein, Linus Daniel Leonhard; Chiarello, Gian Luca

    2014-01-01

    Silica-supported, bimetallic Cu-Ni nanomaterials were prepared with different ratios of Cu to Ni by incipient wetness impregnation without a specific calcination step before reduction. Different in situ characterization techniques, in particular transmission electron microscopy (TEM), X-ray...... diffraction (XRD), and X-ray absorption spectroscopy (XAS), were applied to follow the reduction and alloying process of Cu-Ni nanoparticles on silica. In situ reduction of Cu-Ni samples with structural characterization by combined synchrotron XRD and XAS reveals a strong interaction between Cu and Ni species......, which results in improved reducibility of the Ni species compared with monometallic Ni. At high Ni concentrations silica-supported Cu-Ni alloys form a homogeneous solid solution of Cu and Ni, whereas at lower Ni contents Cu and Ni are partly segregated and form metallic Cu and Cu-Ni alloy phases. Under...

  4. Behavior of heptavalent technetium in concentrated triflic acid under alpha-irradiation. Technetium-triflate complex characterized by X-ray absorption fine structure spectroscopy and DFT

    Energy Technology Data Exchange (ETDEWEB)

    Denden, Ibtihel; Blain, Guillaume; Fattahi, Massoud [SUBATECH Laboratory, Nantes (France); Roques, Jerome [Paris Sud Univ., Orsay (France). IPN Orsay; Poineau, Frederic [Nevada Univ., Las Vegas, NV (United States). Dept. of Chemistry and Biochemistry; Solari, Pier Lorenzo [CEA, Gif-sur-Yvette (France). DEN/DPC/SEARS; Schlegel, Michel L. [Synchrotron SOLEIL, Gif-sur-Yvette (France)

    2017-04-01

    The nature of the Tc species produced after the alpha-irradiation of Tc(VII) in concentrated triflic acid has been investigated by X-ray absorption fine structure (XAFS) spectroscopy and first principles calculations. Experimental and theoretical results are consistent with the formation of Tc{sup (V)}O(F{sub 3}CSO{sub 3}){sub 2}(H{sub 2}O){sub 2}{sup +}.

  5. In situ analysis of the Zn(S,O) buffer layer preparation for chalcopyrite solar cells by Zn L-edge X-ray absorption spectroscopy.

    Science.gov (United States)

    Lauermann, Iver; Kropp, Timo; Vottier, Damien; Ennaoui, Ahmed; Eberhardt, Wolfgang; Aziz, Emad F

    2009-02-23

    Bridging the gap between high-vacuum soft X-ray absorption spectroscopy and real systems under ambient conditions probes chemical reactions in situ during deposition and annealing processes. The origin of highly efficient buffer layers in Zn(S,O) is the complex formation between Zn(2+) and the S=C group of thiourea (see schematic), which allows ligand-to-metal and metal-to-ligand charge transfer (LMCT and MLCT).

  6. Electron delocalization in cyanide-bridged coordination polymer electrodes for Li-ion batteries studied by soft x-ray absorption spectroscopy

    NARCIS (Netherlands)

    Asakura, Daisuke; Okubo, Masashi; Mizuno, Yoshifumi; Kudo, Tetsuichi; Zhou, Haoshen; Amemiya, Kenta; de Groot, Frank M. F.; Chen, Jeng-Lung; Wang, Wei-Cheng; Glans, Per-Anders; Chang, Chinglin; Guo, Jinghua; Honma, Itaru

    2011-01-01

    The electronic structure change during the reversible Li-ion storage reaction in a bimetallic MnFe-Prussian blue analogue (Li(x)K(0.14)Mn(1.43)[Fe(CN)(6)] center dot 6H(2)O) was investigated by soft x-ray absorption spectroscopy. The Mn L(2,3)-edgespectra revealed the unchanged Mn(2+) high-spin

  7. Alternative difference analysis scheme combining R-space EXAFS fit with global optimization XANES fit for X-ray transient absorption spectroscopy.

    Science.gov (United States)

    Zhan, Fei; Tao, Ye; Zhao, Haifeng

    2017-07-01

    Time-resolved X-ray absorption spectroscopy (TR-XAS), based on the laser-pump/X-ray-probe method, is powerful in capturing the change of the geometrical and electronic structure of the absorbing atom upon excitation. TR-XAS data analysis is generally performed on the laser-on minus laser-off difference spectrum. Here, a new analysis scheme is presented for the TR-XAS difference fitting in both the extended X-ray absorption fine-structure (EXAFS) and the X-ray absorption near-edge structure (XANES) regions. R-space EXAFS difference fitting could quickly provide the main quantitative structure change of the first shell. The XANES fitting part introduces a global non-derivative optimization algorithm and optimizes the local structure change in a flexible way where both the core XAS calculation package and the search method in the fitting shell are changeable. The scheme was applied to the TR-XAS difference analysis of Fe(phen) 3 spin crossover complex and yielded reliable distance change and excitation population.

  8. M-edge x-ray absorption spectroscopy: A new tool for dilute mixed-valent materials

    International Nuclear Information System (INIS)

    Kaindl, G.; Brewer, W.D.; Kalkowski, G.; Holtzberg, F.

    1983-01-01

    The valence of Tm compounds is derived from M/sub V/ x-ray absorption spectra recorded by total electron yield under ultra-high-vacuum conditions. For mixed-valent systems the spectra are superpositions of Tm 3+ (three lines) and Tm 2+ (one line) components, providing accurate mean valence values even in highly dilute systems, such as Tm/sub x/Y/sub 1-x/Se, which agree well with those from lattice constant systematics. A surface valence change on TmS(100) is identified as an initial-state effect

  9. X-ray absorption spectroscopy and neutron diffraction study of the perovskite-type rare-earth cobaltites

    Science.gov (United States)

    Sikolenko, V.; Efimova, E.; Franz, A.; Ritter, C.; Troyanchuk, I. O.; Karpinsky, D.; Zubavichus, Y.; Veligzhanin, A.; Tiutiunnikov, S. I.; Sazonov, A.; Efimov, V.

    2018-05-01

    Correlations between local and long-range structure distortions in the perovskite-type RE1-xSrxCoO3-δ (RE = La, Pr, Nd; x = 0.0 and 0.5) compounds have been studied at room temperature by extended X-ray absorption fine structure (EXAFS) at the Co K-edge and high-resolution neutron powder diffraction (NPD). The use of two complementary experimental techniques allowed us to explore the influence of the type of rare-earth element and strontium substitution on unusual behavior of static and dynamic features of both the Co-O bond lengths.

  10. Mechanisms of mercury removal by biochars produced from different feedstocks determined using X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Liu, Peng; Ptacek, Carol J.; Blowes, David W.; Landis, Richard C.

    2016-01-01

    Highlights: • Dissolved Hg decreases by >90% with high-T biochars (600 and 700 °C). • Elevated SO 4 2− (up to 1000 mg L −1 ) is released from manure-derived biochar. • XRF results indicate Hg is distributed heterogeneously throughout biochar particles. • S XANES indicates presence of reduced and oxidized S species in biochar. • Hg EXAFS indicate Hg is bound to S atoms in biochar particle when S content is high. - Abstract: Thirty-six biochars produced from distinct feedstocks at different temperatures were evaluated for their potential to remove mercury (Hg) from aqueous solution at environmentally relevant concentrations. Concentrations of total Hg (THg) decreased by >90% in batch systems containing biochars produced at 600 and 700 °C and by 40–90% for biochars produced at 300 °C. Elevated concentrations of SO 4 2− (up to 1000 mg L −1 ) were observed in solutions mixed with manure-based biochars. Sulfur X-ray absorption near edge structure (XANES) analyses indicate the presence of both reduced and oxidized S species in both unwashed and washed biochars. Sulfur XANES spectra obtained from biochars with adsorbed Hg were similar to those of washed biochars. Micro-X-ray fluorescence mapping results indicate that Hg was heterogeneously distributed across biochar particles. Extended X-ray absorption fine structure modeling indicates Hg was bound to S in biochars with high S content and to O and Cl in biochars with low S content. The predominant mechanisms of Hg removal are likely the formation of chemical bonds between Hg and various functional groups on the biochar. This investigation provides information on the effectiveness and mechanisms of Hg removal that is critical for evaluating biochar applications for stabilization of Hg in surface water, groundwater, soils, and sediments.

  11. Mechanisms of mercury removal by biochars produced from different feedstocks determined using X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Peng [Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1 (Canada); Ptacek, Carol J., E-mail: ptacek@uwaterloo.ca [Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1 (Canada); Blowes, David W. [Department of Earth and Environmental Sciences, University of Waterloo, 200 University Ave. W., Waterloo, ON N2L 3G1 (Canada); Landis, Richard C. [E I. du Pont de Nemours and Company, 974 Centre Road, Wilmington, DE 19805 (United States)

    2016-05-05

    Highlights: • Dissolved Hg decreases by >90% with high-T biochars (600 and 700 °C). • Elevated SO{sub 4}{sup 2−} (up to 1000 mg L{sup −1}) is released from manure-derived biochar. • XRF results indicate Hg is distributed heterogeneously throughout biochar particles. • S XANES indicates presence of reduced and oxidized S species in biochar. • Hg EXAFS indicate Hg is bound to S atoms in biochar particle when S content is high. - Abstract: Thirty-six biochars produced from distinct feedstocks at different temperatures were evaluated for their potential to remove mercury (Hg) from aqueous solution at environmentally relevant concentrations. Concentrations of total Hg (THg) decreased by >90% in batch systems containing biochars produced at 600 and 700 °C and by 40–90% for biochars produced at 300 °C. Elevated concentrations of SO{sub 4}{sup 2−} (up to 1000 mg L{sup −1}) were observed in solutions mixed with manure-based biochars. Sulfur X-ray absorption near edge structure (XANES) analyses indicate the presence of both reduced and oxidized S species in both unwashed and washed biochars. Sulfur XANES spectra obtained from biochars with adsorbed Hg were similar to those of washed biochars. Micro-X-ray fluorescence mapping results indicate that Hg was heterogeneously distributed across biochar particles. Extended X-ray absorption fine structure modeling indicates Hg was bound to S in biochars with high S content and to O and Cl in biochars with low S content. The predominant mechanisms of Hg removal are likely the formation of chemical bonds between Hg and various functional groups on the biochar. This investigation provides information on the effectiveness and mechanisms of Hg removal that is critical for evaluating biochar applications for stabilization of Hg in surface water, groundwater, soils, and sediments.

  12. Sulfur K-edge X-ray absorption spectroscopy and time-dependent density functional theory of arsenic dithiocarbamates.

    Science.gov (United States)

    Donahue, Courtney M; Pacheco, Juan S Lezama; Keith, Jason M; Daly, Scott R

    2014-06-28

    S K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT) calculations were performed on a series of As[S2CNR2]3 complexes, where R2 = Et2, (CH2)5 and Ph2, to determine how dithiocarbamate substituents attached to N affect As[S2CNR2]3 electronic structure. Complimentary [PPh4][S2CNR2] salts were also studied to compare dithiocarbamate bonding in the absence of As. The XAS results indicate that changing the orientation of the alkyl substituents from trans to cis (R2 = Et2vs. (CH2)5) yields subtle variations whereas differences associated with a change from alkyl to aryl are much more pronounced. For example, despite the differences in As 4p mixing, the first features in the S K-edge XAS spectra of [PPh4][S2CNPh2] and As[S2CNPh2]3 were both shifted by 0.3 eV compared to their alkyl-substituted derivatives. DFT calculations revealed that the unique shift observed for [PPh4][S2CNPh2] is due to phenyl-induced splitting of the π* orbitals delocalized over N, C and S. A similar phenomenon accounts for the shift observed for As[S2CNPh2]3, but the presence of two unique S environments (As-S and As···S) prevented reliable analysis of As-S covalency from the XAS data. In the absence of experimental values, DFT calculations revealed a decrease in As-S orbital mixing in As[S2CNPh2]3 that stems from a redistribution of electron density to S atoms participating in weaker As···S interactions. Simulated spectra obtained from TDDFT calculations reproduce the experimental differences in the S K-edge XAS data, which suggests that the theory is accurately modeling the experimental differences in As-S orbital mixing. The results highlight how S K-edge XAS and DFT can be used cooperatively to understand the electronic structure of low symmetry coordination complexes containing S atoms in different chemical environments.

  13. Sulfur X-Ray Absorption Spectroscopy of Living Mammalian Cells: An Enabling Tool for Sulfur Metabolomics. in Situ Observation of Uptake of Taurine Into MDCK Cells

    Energy Technology Data Exchange (ETDEWEB)

    Gnida, M.; Sneeden, E.Yu; Whitin, J.C.; Prince, R.C.; Pickering, I.J.; Korbas, M.; George, G.N.

    2009-06-01

    Sulfur is essential for life, with important roles in biological structure and function. However, because of a lack of suitable biophysical techniques, in situ information about sulfur biochemistry is generally difficult to obtain. Here, we present an in situ sulfur X-ray absorption spectroscopy (S-XAS) study of living cell cultures of the mammalian renal epithelial MDCK cell line. A great deal of information is retrieved from a characteristic sulfonate feature in the X-ray absorption spectrum of the cell cultures, which can be related to the amino acid taurine. We followed the time and dose dependence of uptake of taurine into MDCK cell monolayers. The corresponding uptake curves showed a typical saturation behavior with considerable levels of taurine accumulation inside the cells (as much as 40% of total cellular sulfur). We also investigated the polarity of uptake of taurine into MDCK cells, and our results confirmed that uptake in situ is predominantly a function of the basolateral cell surface.

  14. Preliminary characterization of calcium chemical environment in apatitic and non-apatitic calcium phosphates of biological interest by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Eichert, D.; Salome, M.; Banu, M.; Susini, J.; Rey, C.

    2005-01-01

    Several reports have mentioned the existence of non-apatitic environments of phosphate and carbonate ions in synthetic and biological poorly crystalline apatites. However there were no direct spectroscopic evidences for the existence of non-apatitic environment of calcium ions. X-ray Absorption Spectroscopy, at the K-edge of calcium, allows the discrimination between different calcium phosphates of biological interest despite great spectral similarities. A primary analysis of the spectra reveals the existence, in synthetic poorly crystalline apatites, of variable features related to the maturation stage of the sample and corresponding to the existence of non-apatitic environments of calcium ions. Although these features can also be found in several other calcium phosphate salts, and do not allow a clear identification of the ionic environments of calcium ions, they give a possibility to directly determine the maturity of poorly crystalline apatite from calcium X-ray Absorption Near Edge Structure spectra

  15. Biological X-ray absorption spectroscopy (BioXAS): a valuable tool for the study of trace elements in the life sciences.

    Science.gov (United States)

    Strange, Richard W; Feiters, Martin C

    2008-10-01

    Using X-ray absorption spectroscopy (XAS) the binding modes (type and number of ligands, distances and geometry) and oxidation states of metals and other trace elements in crystalline as well as non-crystalline samples can be revealed. The method may be applied to biological systems as a 'stand-alone' technique, but it is particularly powerful when used alongside other X-ray and spectroscopic techniques and computational approaches. In this review, we highlight how biological XAS is being used in concert with crystallography, spectroscopy and computational chemistry to study metalloproteins in crystals, and report recent applications on relatively rare trace elements utilised by living organisms and metals involved in neurodegenerative diseases.

  16. K- and L-edge X-ray Absorption Spectroscopy (XAS) and Resonant Inelastic X-ray Scattering (RIXS) Determination of Differential Orbital Covalency (DOC) of Transition Metal Sites.

    Science.gov (United States)

    Baker, Michael L; Mara, Michael W; Yan, James J; Hodgson, Keith O; Hedman, Britt; Solomon, Edward I

    2017-08-15

    Continual advancements in the development of synchrotron radiation sources have resulted in X-ray based spectroscopic techniques capable of probing the electronic and structural properties of numerous systems. This review gives an overview of the application of metal K-edge and L-edge X-ray absorption spectroscopy (XAS), as well as K resonant inelastic X-ray scattering (RIXS), to the study of electronic structure in transition metal sites with emphasis on experimentally quantifying 3d orbital covalency. The specific sensitivities of K-edge XAS, L-edge XAS, and RIXS are discussed emphasizing the complementary nature of the methods. L-edge XAS and RIXS are sensitive to mixing between 3d orbitals and ligand valence orbitals, and to the differential orbital covalency (DOC), that is, the difference in the covalencies for different symmetry sets of the d orbitals. Both L-edge XAS and RIXS are highly sensitive to and enable separation of and donor bonding and back bonding contributions to bonding. Applying ligand field multiplet simulations, including charge transfer via valence bond configuration interactions, DOC can be obtained for direct comparison with density functional theory calculations and to understand chemical trends. The application of RIXS as a probe of frontier molecular orbitals in a heme enzyme demonstrates the potential of this method for the study of metal sites in highly covalent coordination sites in bioinorganic chemistry.

  17. Silver in geological fluids from in situ X-ray absorption spectroscopy and first-principles molecular dynamics

    Science.gov (United States)

    Pokrovski, Gleb S.; Roux, Jacques; Ferlat, Guillaume; Jonchiere, Romain; Seitsonen, Ari P.; Vuilleumier, Rodolphe; Hazemann, Jean-Louis

    2013-04-01

    The molecular structure and stability of species formed by silver in aqueous saline solutions typical of hydrothermal settings were quantified using in situ X-ray absorption spectroscopy (XAS) measurements, quantum-chemical modeling of near-edge absorption spectra (XANES) and extended fine structure spectra (EXAFS), and first-principles molecular dynamics (FPMD). Results show that in nitrate-bearing acidic solutions to at least 200 °C, silver speciation is dominated by the hydrated Ag+ cation surrounded by 4-6 water molecules in its nearest coordination shell with mean Ag-O distances of 2.32 ± 0.02 Å. In NaCl-bearing acidic aqueous solutions of total Cl concentration from 0.7 to 5.9 mol/kg H2O (m) at temperatures from 200 to 450 °C and pressures to 750 bar, the dominant species are the di-chloride complex AgCl2- with Ag-Cl distances of 2.40 ± 0.02 Å and Cl-Ag-Cl angle of 160 ± 10°, and the tri-chloride complex AgCl32- of a triangular structure and mean Ag-Cl distances of 2.60 ± 0.05 Å. With increasing temperature, the contribution of the tri-chloride species decreases from ˜50% of total dissolved Ag in the most concentrated solution (5.9m Cl) at 200 °C to less than 10-20% at supercritical temperatures for all investigated solutions, so that AgCl2- becomes by far the dominant Ag-bearing species at conditions typical of hydrothermal-magmatic fluids. Both di- and tri-chloride species exhibit outer-sphere interactions with the solvent as shown by the detection, using FPMD modeling, of H2O, Cl-, and Na+ at distances of 3-4 Å from the silver atom. The species fractions derived from XAS and FPMD analyses, and total AgCl(s) solubilities, measured in situ in this work from the absorption edge height of XAS spectra, are in accord with thermodynamic predictions using the stability constants of AgCl2- and AgCl32- from Akinfiev and Zotov (2001) and Zotov et al. (1995), respectively, which are based on extensive previous AgCl(s) solubility measurements. These data

  18. Hydrogen absorption in epitaxial W/Nb(001) and polycrystalline Fe/Nb(110) multilayers studied in-situ by X-ray/neutron scattering techniques and X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Klose, F.; Rehm, C.; Fieber-Erdmann, M.; Holub-Krappe, E.; Bleif, H. J.; Sowers, H.; Goyette, R.; Troger, L.; Maletta, H.

    1999-01-01

    Hydrogen can be absorbed in large quantities by 100 A thin Nb layers embedded in epitaxial W/Nb and polycrystalline Fe/Nb multilayers. The solubility and the hydrogen-induced structural changes of the host lattice are explored in-situ by small-angle neutron/X-ray reflectometry and high-angle diffraction. These measurements reveal for both systems that the relative out-of-plane expansion of the Nb layers is considerably larger than the relative increase of the Nb interplanar spacing indicating two distinctly different mechanisms of hydrogen absorption. In Fe/Nb multilayers, hydrogen expands the Nb interplanar spacing in a continuous way as function of the external pressure. In contrast, the Nb lattice expansion is discontinuous in epitaxial W/Nb multilayers: A jump in the Nb(002) Bragg reflection position occurs at a critical hydrogen pressure of 1 mbar. In-situ EXAFS spectroscopy also exhibits an irreversible expansion of the Nb lattice in the film plane for p H2 > 1 mbar. This can be regarded as a structural phase transition from an exclusively out-of-plane to a three-dimensionally expanded state at low and high hydrogen pressures, respectively

  19. Role of Bi promotion and solvent in platinum-catalyzed alcohol oxidation probed by in situ X-ray absorption and ATR-IR spectroscopy

    DEFF Research Database (Denmark)

    Mondelli, C.; Grunwaldt, Jan-Dierk; Ferri, D.

    2010-01-01

    the catalysts under working conditions using in situ X-ray absorption spectroscopy (XAS) and attenuated total reflection infrared spectroscopy (ATR-IR), aiming at uncovering the roles of the metal promoter and the reaction medium. XAS confirms that Bi is oxidized more easily than Pt, maintaining the catalytic...... surfaces than on step or kink sites. Side products, CO and benzoate species, appearing during the reaction reveal that the geometric suppression of undesired reactions does not occur to the same extent on Pt-based catalysts as on Pd, suggesting that decarbonylation of the produced aldehyde on Pt may occur...

  20. Relationship between x-ray emission and absorption spectroscopy and the local H-bond environment in water.

    Science.gov (United States)

    Zhovtobriukh, Iurii; Besley, Nicholas A; Fransson, Thomas; Nilsson, Anders; Pettersson, Lars G M

    2018-04-14

    The connection between specific features in the water X-ray absorption spectrum and X-ray emission spectrum (XES) and the local H-bond coordination is studied based on structures obtained from path-integral molecular dynamics simulations using either the opt-PBE-vdW density functional or the MB-pol force field. Computing the XES spectrum using all molecules in a snapshot results in only one peak in the lone-pair (1b 1 ) region, while the experiment shows two peaks separated by 0.8-0.9 eV. Different H-bond configurations were classified based on the local structure index (LSI) and a geometrical H-bond cone criterion. We find that tetrahedrally coordinated molecules characterized by high LSI values and two strong donated and two strong accepted H-bonds contribute to the low energy 1b 1 emission peak and to the post-edge region in absorption. Molecules with the asymmetric H-bond environment with one strong accepted H-bond and one strong donated H-bond and low LSI values give rise to the high energy 1b 1 peak in the emission spectrum and mainly contribute to the pre-edge and main-edge in the absorption spectrum. The 1b 1 peak splitting can be increased to 0.62 eV by imposing constraints on the H-bond length, i.e., for very tetrahedral structures short H-bonds (less than 2.68 Å) and for very asymmetric structures elongated H-bonds (longer than 2.8 Å). Such structures are present, but underrepresented, in the simulations which give more of an average of the two extremes.

  1. Relationship between x-ray emission and absorption spectroscopy and the local H-bond environment in water

    Science.gov (United States)

    Zhovtobriukh, Iurii; Besley, Nicholas A.; Fransson, Thomas; Nilsson, Anders; Pettersson, Lars G. M.

    2018-04-01

    The connection between specific features in the water X-ray absorption spectrum and X-ray emission spectrum (XES) and the local H-bond coordination is studied based on structures obtained from path-integral molecular dynamics simulations using either the opt-PBE-vdW density functional or the MB-pol force field. Computing the XES spectrum using all molecules in a snapshot results in only one peak in the lone-pair (1b1) region, while the experiment shows two peaks separated by 0.8-0.9 eV. Different H-bond configurations were classified based on the local structure index (LSI) and a geometrical H-bond cone criterion. We find that tetrahedrally coordinated molecules characterized by high LSI values and two strong donated and two strong accepted H-bonds contribute to the low energy 1b1 emission peak and to the post-edge region in absorption. Molecules with the asymmetric H-bond environment with one strong accepted H-bond and one strong donated H-bond and low LSI values give rise to the high energy 1b1 peak in the emission spectrum and mainly contribute to the pre-edge and main-edge in the absorption spectrum. The 1b1 peak splitting can be increased to 0.62 eV by imposing constraints on the H-bond length, i.e., for very tetrahedral structures short H-bonds (less than 2.68 Å) and for very asymmetric structures elongated H-bonds (longer than 2.8 Å). Such structures are present, but underrepresented, in the simulations which give more of an average of the two extremes.

  2. Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets

    Energy Technology Data Exchange (ETDEWEB)

    Saykally, Richard J; Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

    2008-01-08

    We describe an approach for characterizing selective binding between oppositely charged ionic functional groups under biologically relevant conditions. Relative shifts in K-shell x-ray absorption spectra of aqueous cations and carboxylate anions indicate the corresponding binding strengths via perturbations of carbonyl antibonding orbitals. XAS spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium cations reveal monotonically stronger binding of the lighter metals, supporting recent results from simulations and other experiments. The carbon K-edge spectra of the acetate carbonyl feature centered near 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent with formate. These results are in accord with the Law of Matching Water Affinities, relating relative hydration strengths of ions to their respective tendencies to form contact ion pairs. Density functional theory calculations of K-shell spectra support the experimental findings.

  3. Characterization of selective binding of alkali cations with carboxylate by x-ray absorption spectroscopy of liquid microjets

    International Nuclear Information System (INIS)

    Saykally, Richard J; Uejio, Janel S.; Schwartz, Craig P.; Duffin, Andrew M.; Drisdell, Walter S.; Cohen, Ronald C.; Saykally, Richard J.

    2008-01-01

    We describe an approach for characterizing selective binding between oppositely charged ionic functional groups under biologically relevant conditions. Relative shifts in K-shell x-ray absorption spectra of aqueous cations and carboxylate anions indicate the corresponding binding strengths via perturbations of carbonyl antibonding orbitals. XAS spectra measured for aqueous formate and acetate solutions containing lithium, sodium, and potassium cations reveal monotonically stronger binding of the lighter metals, supporting recent results from simulations and other experiments. The carbon K-edge spectra of the acetate carbonyl feature centered near 290 eV clearly indicate a preferential interaction of sodium versus potassium, which was less apparent with formate. These results are in accord with the Law of Matching Water Affinities, relating relative hydration strengths of ions to their respective tendencies to form contact ion pairs. Density functional theory calculations of K-shell spectra support the experimental findings

  4. Photoinduced charge transfer in a transition metal complex investigated by time-resolved X-ray absorption fine structure spectroscopy. Setup and experiment

    International Nuclear Information System (INIS)

    Goeries, Dennis

    2015-02-01

    In the framework of this thesis the development of a time-resolved X-ray absorption spectroscopy experiment and its application to fac-Ir(ppy) 3 is described. Such experiments require a very stable setup in terms of spatial and temporal accuracy. Therefore, the stability properties of the present installation were investigated in detail and continuously improved, in particular the synchronization of the ultrashort pulse laser system to the storage ring as well as the spatial stability of both X-ray and laser beam. Experiments utilizing the laser pump and X-ray probe configuration were applied on the green phosphorescence emitter complex fac-Ir(ppy) 3 dissolved in dimethyl sulfoxide. Structural and electronic changes were triggered by photoexcitation of the metal-to-ligand charge transfer band with ultrashort laser pulses at a wavelength of 343 nm. The excited triplet state spectrum was extracted from the measured pump-probe X-ray absorption spectrum using an ionic approximation. The results con rm the anticipated metal-to-ligand charge transfer as shown by an ionization potential shift of the iridium atom. The symmetry of the complex was found to be pseudo-octahedral. This allowed the first experimental determination of the bond length of fac-Ir(ppy) 3 in an octahedral approximation and revealed a decrease of bond length of the first coordination shell in the triplet state. The first and second-order decay kinetics of the triplet state were investigated in a combination of X-ray and laser based experiments and revealed self-quenching as well as triplet-triplet annihilation rate constants.

  5. Influence of interstitial solutions (H, N) on cerium electronic state in Ce-Fe intermetallic compounds: X-ray Absorption Spectroscopy (XAS) study

    International Nuclear Information System (INIS)

    Chaboy, J.; Marcelli, A.; Bozukov, L.

    1995-03-01

    It is presented an x-ray absorption spectroscopy (XAS) investigation performed at the L-edges of the rare-earth and at the K-edge of iron in the R-Fe intermetallic compounds (La, Ce) 2 Fe 14 BH χ and Ce 2 Fe 17 (H,N) χ , to elucidate the role of the interstitial doping into the electronic and magnetic properties of these systems. Comparison with x-ray circular magnetic dichroism (XCMD) experiments has been carried out to clarify the localization of 4f magnetic moment at the Ce sites upon hydriding. Both XAS and XCMD results evidence the interplay between the structural and magnetic changes, that are associated to the modification of the hybridization between the Fe(3d) and Ce(5d) bands

  6. X-ray and photoelectron spectroscopy of light rare earths

    International Nuclear Information System (INIS)

    Fuggle, J.C.

    1983-01-01

    Core level photoelectron spectroscopy, X-ray absorption spectroscopy, bremsstrahlung isochromat spectroscopy and valence band studies are discussed. Particular emphasis is placed on cerium. Correlation effects, multiplet structure, screening effects and the dynamics of the processes involved are illustrated with selected examples. (Auth.)

  7. Room temperature redox reaction by oxide ion migration at carbon/Gd-doped CeO2 heterointerface probed by an in situ hard x-ray photoemission and soft x-ray absorption spectroscopies

    Directory of Open Access Journals (Sweden)

    Takashi Tsuchiya, Shogo Miyoshi, Yoshiyuki Yamashita, Hideki Yoshikawa, Kazuya Terabe, Keisuke Kobayashi and Shu Yamaguchi

    2013-01-01

    Full Text Available In situ hard x-ray photoemission spectroscopy (HX-PES and soft x-ray absorption spectroscopy (SX-XAS have been employed to investigate a local redox reaction at the carbon/Gd-doped CeO2 (GDC thin film heterointerface under applied dc bias. In HX-PES, Ce3d and O1s core levels show a parallel chemical shift as large as 3.2 eV, corresponding to the redox window where ionic conductivity is predominant. The window width is equal to the energy gap between donor and acceptor levels of the GDC electrolyte. The Ce M-edge SX-XAS spectra also show a considerable increase of Ce3+ satellite peak intensity, corresponding to electrochemical reduction by oxide ion migration. In addition to the reversible redox reaction, two distinct phenomena by the electrochemical transport of oxide ions are observed as an irreversible reduction of the entire oxide film by O2 evolution from the GDC film to the gas phase, as well as a vigorous precipitation of oxygen gas at the bottom electrode to lift off the GDC film. These in situ spectroscopic observations describe well the electrochemical polarization behavior of a metal/GDC/metal capacitor-like two-electrode cell at room temperature.

  8. Development of an x-ray beam line at the NSLS for studies in materials science using x-ray absorption spectroscopy. Progress report, February 1, 1985-January 31, 1986

    International Nuclear Information System (INIS)

    Sayers, D.E.

    1984-01-01

    Research is reported for x-ray studies at NSLS. Energy-loss spectroscopy experiments (EXAFS) were performed on various materials including iron, silicon, gold, glass, niobium-aluminum alloys, and metglass

  9. Direct speciation analysis of arsenic in sub-cellular compartments using micro-X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Bacquart, Thomas; Deves, Guillaume; Ortega, Richard

    2010-01-01

    Identification of arsenic chemical species at a sub-cellular level is a key to understanding the mechanisms involved in arsenic toxicology and antitumor pharmacology. When performed with a microbeam, X-ray absorption near-edge structure (μ-XANES) enables the direct speciation analysis of arsenic in sub-cellular compartments avoiding cell fractionation and other preparation steps that might modify the chemical species. This methodology couples tracking of cellular organelles in a single cell by confocal or epifluorescence microscopy with local analysis of chemical species by μ-XANES. Here we report the results obtained with a μ-XANES experimental setup based on Kirkpatrick-Baez X-ray focusing optics that maintains high flux of incoming radiation (>10 11 ph/s) at micrometric spatial resolution (1.5x4.0 μm 2 ). This original experimental setup enabled the direct speciation analysis of arsenic in sub-cellular organelles with a 10 -15 g detection limit. μ-XANES shows that inorganic arsenite, As(OH) 3 , is the main form of arsenic in the cytosol, nucleus, and mitochondrial network of cultured cancer cells exposed to As 2 O 3 . On the other hand, a predominance of As(III) species is observed in HepG2 cells exposed to As(OH) 3 with, in some cases, oxidation to a pentavalent form in nuclear structures of HepG2 cells. The observation of intra-nuclear mixed redox states suggests an inter-individual variability in a cell population that can only be evidenced with direct sub-cellular speciation analysis.

  10. X-Ray Magnetic Dichroism of Antiferromagnet Fe2O3 : The Orientation of Magnetic Moments Observed by Fe 2p X-Ray Absorption Spectroscopy

    NARCIS (Netherlands)

    Kuiper, Pieter; Searle, Barry G.; Rudolf, Petra; Tjeng, L.H.; Chen, C.T.

    1993-01-01

    We report strong magnetic linear dichroism at the Fe L2,3 edge of the antiferromagnet Fe2O3 (hematite). The relative difference in absorption for light polarized parallel and perpendicular to the magnetic moment is as high as 40% at the Fe L2 edge. The spectra are in excellent agreement with

  11. New set-up for high-quality soft-X-ray absorption spectroscopy of large organic molecules in the gas phase

    Energy Technology Data Exchange (ETDEWEB)

    Holch, Florian; Huebner, Dominique [Universitaet Wuerzburg, Experimentelle Physik VII, Am and Roentgen Reasearch Center for Complex Materials (RCCM) Hubland, 97074 Wuerzburg (Germany); Fink, Rainer [Universitaet Erlangen-Nuernberg, ICMM and CENEM, Egerlandstrasse 3, 91058 Erlangen (Germany); Schoell, Achim, E-mail: achim.schoell@physik.uni-wuerzburg.de [Universitaet Wuerzburg, Experimentelle Physik VII, Am and Roentgen Reasearch Center for Complex Materials (RCCM) Hubland, 97074 Wuerzburg (Germany); Umbach, Eberhard [Karlsruhe Institute of Technology, 76021 Karlsruhe (Germany)

    2011-11-15

    Highlights: {yields} We present a new set-up for x-ray absorption (NEXAFS) on large molecules in the gas-phase. {yields} The cell has a confined volume and can be heated. {yields} The spectra can be acquired fast, are of very high quality with respect tosignal-to-noise ratio and energy resolution. {yields} This allowsthe analysis of spectroscopic details (e.g. solid state effects by comparing gas- and condensed phase data). - Abstract: We present a new experimental set-up for the investigation of large (>128 amu) organic molecules in the gas-phase by means of near-edge X-ray absorption fine structure spectroscopy in the soft X-ray range. Our approach uses a gas cell, which is sealed off against the surrounding vacuum and which can be heated above the sublimation temperature of the respective molecular compound. Using a confined volume rather than a molecular beam yields short acquisition times and intense signals due to the high molecular density, which can be tuned by the container temperature. In turn, the resulting spectra are of very high quality with respect to signal-to-noise ratio and energy resolution, which are the essential aspects for the analysis of fine spectroscopic details. Using the examples of ANQ, NTCDA, and PTCDA, specific challenges of gas phase measurements on large organic molecules with high sublimation temperatures are addressed in detail with respect to the presented set-up and possible ways to tackle them are outlined.

  12. Origin of the chemical shift in X-ray absorption near-edge spectroscopy at the Mn K-Edge in manganese oxide compounds

    NARCIS (Netherlands)

    de Vries, AH; Hozoi, L.; Broer, R.

    2003-01-01

    The absorption edge in Mn K-edge X-ray absorption spectra of manganese oxide compounds shows a shift of several electronvolts in going from MnO through LaMnO3 to CaMnO3. On the other hand, in X-ray photoelectron spectra much smaller shifts are observed. To identify the mechanisms that cause the

  13. The nature of chemical bonding in actinide and lanthanide ferrocyanides determined by X-ray absorption spectroscopy and density functional theory.

    Science.gov (United States)

    Dumas, Thomas; Guillaumont, Dominique; Fillaux, Clara; Scheinost, Andreas; Moisy, Philippe; Petit, Sébastien; Shuh, David K; Tyliszczak, Tolek; Den Auwer, Christophe

    2016-01-28

    The electronic properties of actinide cations are of fundamental interest to describe intramolecular interactions and chemical bonding in the context of nuclear waste reprocessing or direct storage. The 5f and 6d orbitals are the first partially or totally vacant states in these elements, and the nature of the actinide ligand bonds is related to their ability to overlap with ligand orbitals. Because of its chemical and orbital selectivities, X-ray absorption spectroscopy (XAS) is an effective probe of actinide species frontier orbitals and for understanding actinide cation reactivity toward chelating ligands. The soft X-ray probes of the light elements provide better resolution than actinide L3-edges to obtain electronic information from the ligand. Thus coupling simulations to experimental soft X-ray spectral measurements and complementary quantum chemical calculations yields quantitative information on chemical bonding. In this study, soft X-ray XAS at the K-edges of C and N, and the L2,3-edges of Fe was used to investigate the electronic structures of the well-known ferrocyanide complexes K4Fe(II)(CN)6, thorium hexacyanoferrate Th(IV)Fe(II)(CN)6, and neodymium hexacyanoferrate KNd(III)Fe(II)(CN)6. The soft X-ray spectra were simulated based on quantum chemical calculations. Our results highlight the orbital overlapping effects and atomic effective charges in the Fe(II)(CN)6 building block. In addition to providing a detailed description of the electronic structure of the ferrocyanide complex (K4Fe(II)(CN)6), the results strongly contribute to confirming the actinide 5f and 6d orbital oddity in comparison to lanthanide 4f and 5d.

  14. Very first tests on SOLEIL regarding the Zn environment in pathological calcifications made of apatite determined by X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bazin, D.; Carpentier, X.; Traxer, O.; Thiaudiere, D.; Somogyi, A.; Reguer, S.; Waychunas, G.; Daudon, M.

    2008-10-01

    This very first report of a X-ray absorption spectroscopy experiment on Soleil is part of a more large long term study dedicated to ectopic calcifications. Such biological entities composed of various inorganic and/or organic compounds contain also trace elements. In the case of urinary calculi, different papers already published point out that these oligo elements may promote or inhibit crystal nucleation or growth of mineral or organic species involved. By using such tool specific to synchrotron radiation i.e. determine the local environment of oligoelements and thus their occupation site, we contribute to our understanding of the role of trace elements in ectopic calcifications.

  15. Structure of Co-Doped Alq3 thin films investigated by grazing incidence X-ray absorption fine structure and Fourier transform infrared spectroscopy.

    Science.gov (United States)

    Lin, Liang; Pang, Zhiyong; Fang, Shaojie; Wang, Fenggong; Song, Shumei; Huang, Yuying; Wei, Xiangjun; Yu, Haisheng; Han, Shenghao

    2011-02-10

    The structural properties of Co-doped tris(8-hydroxyquinoline)aluminum (Alq(3)) have been studied by grazing incidence X-ray absorption fine structure (GIXAFS) and Fourier transform infrared spectroscopy (FTIR). GIXAFS analysis suggests that there are multivalent Co-Alq(3) complexes and the doped Co atoms tend to locate at the attraction center with respect to N and O atoms and bond with them. The FTIR spectra indicate that the Co atoms interact with the meridional (mer) isomer of Alq(3) rather than forming inorganic compounds.

  16. Structural Disorder in Colloidal InAs and CdSe Nanocrystals Observed by X-Ray Absorption Near-Edge Spectroscopy

    International Nuclear Information System (INIS)

    Hamad, K.S.; Hamad, K.S.; Roth, R.; Roth, R.; Rockenberger, J.; Rockenberger, J.; Alivisatos, A.P.; Alivisatos, A.P.; Buuren, T. van

    1999-01-01

    We report the observation of size dependent structural disorder by x-ray absorption near-edge spectroscopy (XANES) in InAs and CdSe nanocrystals 17 - 80 Angstrom in diameter. XANES of the In and Cd M 4,5 edges yields features that are sharp for the bulk solid but broaden considerably as the size of the particle decreases. FEFF7 multiple-scattering simulations reproduce the size dependent broadening of the spectra if a bulklike surface reconstruction of a spherical nanocrystal model is included. This illustrates that XANES is sensitive to the structure of the entire nanocrystal including the surface. copyright 1999 The American Physical Society

  17. X-ray absorption spectroscopy of single-crystalline (VO)2P2O7: Electronic structure and possible exchange paths

    International Nuclear Information System (INIS)

    Gerhold, S.; Nu''cker, N.; Kuntscher, C. A.; Schuppler, S.; Stadler, S.; Idzerda, Y. U.; Prokofiev, A. V.; Bu''llesfeld, F.; Assmus, W.

    2001-01-01

    Using polarization-dependent V2p and O1s near-edge x-ray absorption spectroscopy, we studied the unoccupied electronic structure of single-crystalline (VO) 2 P 2 O 7 . It is highly anisotropic, and shows similarities to vanadium oxides like VO 2 and V 2 O 5 at the V2p edge and at the O1s threshold. The contributions from V-O and P-O orbitals could be identified. The results rule out the spin ladder model for the magnetic behavior of (VO) 2 P 2 O 7 , but are consistent with the alternating chain scenario

  18. Very first tests on SOLEIL regarding the Zn environment in pathological calcifications made of apatite determined by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Bazin, D.; Carpentier, X.; Traxer, O.; Thiaudiere, D.; Somogyi, A.; Reguer, S.; Waychunas, G.; Daudon, M.

    2008-01-01

    This very first report of a X-ray absorption spectroscopy experiment on Soleil is part of a more large long term study dedicated to ectopic calcifications. Such biological entities composed of various inorganic and/or organic compounds contain also trace elements. In the case of urinary calculi, different papers already published point out that these oligo elements may promote or inhibit crystal nucleation or growth of mineral or organic species involved. By using such tool specific to synchrotron radiation i.e. determine the local environment of oligoelements and thus their occupation site, we contribute to our understanding of the role of trace elements in ectopic calcifications

  19. Investigation of electronic states of infinite-layer SrFeO2 epitaxial thin films by X-ray photoemission and absorption spectroscopies

    International Nuclear Information System (INIS)

    Chikamatsu, Akira; Matsuyama, Toshiya; Hirose, Yasushi; Kumigashira, Hiroshi; Oshima, Masaharu; Hasegawa, Tetsuya

    2012-01-01

    Highlights: ► Electronic states of infinite-layer SrFeO 2 films have been experimentally observed. ► Fe 3d states have higher densities of states in the valence-band region. ► Three peaks derived from Fe 3d states were observed in the conduction-band region. ► Indirect bandgap value was determined to be 1.3 eV. - Abstract: We investigated the electronic states of a single-crystal SrFeO 2 epitaxial thin film in the valence-band and conduction-band regions using synchrotron-radiation X-ray photoemission and absorption spectroscopies. Fe 2p–3d resonant photoemission measurements revealed that the Fe 3d states have higher densities of states at binding energies of 3–5 eV and 5–8.5 eV in the valence-band region. The O K-edge X-ray absorption spectrum exhibited three peaks in the Fe 3d-derived conduction band hybridized with O 2p states; these can be assigned to Fe 3d xy , 3d xz + 3d yz , and 3d x 2 –y 2 . In addition, the indirect bandgap value of the SrFeO 2 film was determined to be 1.3 eV by transmission and absorption spectroscopies.

  20. X-ray absorption spectroscopy study of the LixFePO4 cathode during cycling using a novel electrochemical in situ reaction cell

    International Nuclear Information System (INIS)

    Deb, A.; Bergmann, U.; Cairns, E.L.; California Univ., Berkeley, CA; Cramer, S.P.; California Univ., Davis, CA

    2004-01-01

    The extraction and insertion of lithium in LiFePO 4 has been investigated in practical Li-ion intercalation electrodes for Li-ion batteries using Fe K-edge X-ray absorption spectroscopy (XAS). A versatile electrochemical in situ reaction cell was utilized, specifically designed for long-term X-ray experiments on battery electrodes during the lithium-extraction/insertion process in electrode materials for Li-ion batteries. The electrode contained about 7.7 mg of LiFePO 4 on a 20 μm-thick Al foil. In order to determine the charge compensation mechanism and structural perturbations occurring in the system during cycling, in situ X-ray absorption fine-structure spectroscopy (XAFS) measurements were conducted on the cell at a moderate rate using typical Li-ion battery operating voltages (3.0-4.1 V versus Li/Li + ).XAS studies of the LiFePO 4 electrode measured at the initial state (LiFePO 4 ) showed iron to be in the Fe(II) state corresponding to the initial state (0.0 mAh) of the battery, whereas in the delithiated state (FePO 4 ) iron was found to be in the FE(III) state corresponding to the final charged state (3 m Ah) of the battery. The X-ray absorption near-edge structure (XANES) region of the XAS spectra revealed a high-spin configuration for the two states [Fe(II), d 6 and Fe(III), d 5 ]. The XAFS data analysis confirmed that the olivine structure of the LeFePO 4 and FePO 4 is retained by the electrodes, which is in agreement with the X-ray diffraction observations on these compounds. The XAFS data that were collected continuously during cycling revealed details about the response of the cathode to Li insertion and extraction. These measurements on the LiFePO 4 cathode show that the material retains good structural short-range order leading to superior cycling

  1. X-ray absorption near edge spectroscopy at the Mn K-edge in highly homogeneous GaMnN diluted magnetic semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Sancho-Juan, O.; Cantarero, A.; Garro, N.; Cros, A. [Materials Science Institute, University of Valencia, PO Box 22085, 46071 Valencia (Spain); Martinez-Criado, G.; Salome, M.; Susini, J. [ESRF, Polygone Scientifique Louis Neel, 6 rue Jules Horowitz, 38000 Grenoble (France); Olguin, D. [Dept. de Fisica, CINVESTAV-IPN, 07300 Mexico D.F. (Mexico); Dhar, S.; Ploog, K. [Paul Drude Institute, Hausvogteiplatz 5-7, 10117 Berlin (Germany)

    2006-06-15

    We have studied by X-ray absorption spectroscopy the local environment of Mn in highly homogeneous Ga{sub 1-x}Mn{sub x}N (0.06X-ray absorption near edge spectroscopy (XANES) results. The comparison of the XANES spectra corresponding to the Ga and Mn edges indicates that Mn is substitutional to Ga in all samples studied. The XANES spectra measured at the Mn absorption edge shows in the near-edge region a double peak and a shoulder below the absorption edge and the main absorption peak after the edge, separated around 15 eV above the pre-edge structure. We have compared the position of the edge with that of MnO (Mn{sup 2+}) and Mn{sub 2}O{sub 3} (Mn{sup 3+}). All samples studied present the same Mn oxidation state, 2{sup +}. In order to interprete the near-edge structure, we have performed ab initio calculations with a 2 x 2 x 1supercell ({proportional_to}6% Mn) using the full potential linear augmented plane wave method as implemented in the Wien2k code. The calculations show the appearance of Mn anti-bonding t{sub 2g} bands, which are responsible for the pre-edge absorption. The shoulder and main absorption peaks are due to transitions from the valence band 1s-states of Mn to the p-contributions of the conduction bands. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  2. Protonium X-ray spectroscopy

    CERN Document Server

    Gotta, D

    1999-01-01

    The Lyman and Balmer transitions from antiprotonic hydrogen and deuterium were studied extensively at the low-energy-antiproton ring LEAR at CERN in order to determine the strong interaction effects. A first series of experiments $9 was performed with semiconductor and gaseous X-ray detectors. In the last years of LEAR operation using a Bragg crystal spectrometer, strong interaction parameters in the 2p states of antiprotonic hydrogen and deuterium were measured $9 directly. The results of the measurements support the meson-exchange models describing the medium and long range part of the nucleon-antinucleon interaction. (39 refs).

  3. Evidence for the presence of U-Mo-Al ternary compounds in the U-Mo/Al interaction layer grown by thermal annealing: a coupled micro X-ray diffraction and micro X-ray absorption spectroscopy study

    International Nuclear Information System (INIS)

    Palancher, H.; Martin, P.; Nassif, V.

    2007-01-01

    The systematic presence of the ternary phases U 6 Mo 4 Al 43 and UMo 2 Al 20 is reported in a U-Mo/Al interaction layer grown by thermal annealing. This work shows, therefore, the low Mo solubility in UAl 3 and UAl 4 binary phases; it contradicts the hypothesis of the formation of (U,Mo)Al 3 and (U,Mo)Al 4 solid solutions often admitted in the literature. Using μ-XAS (micro X-ray absorption spectroscopy) at the Mo K edge and μ-XRD (micro X-ray diffraction), the heterogeneity of the interaction layer obtained on a γ-U 0.85 Mo 0.15 /Al diffusion couple has been precisely investigated. The UMo 2 Al 20 phase has been identified at the closest location from the Al side. Moreover, μ-XRD mapping performed on an annealed fuel plate enabled the characterization of the four phases resulting from the γ-U 0.85 Mo 0.15 /Al and (U 2 Mo+α-U)/Al interactions. A strong correlation between the concentrations of UAl 4 and UMo 2 Al 20 and those of UAl 3 and U 6 Mo 4 Al 43 has been shown. (orig.)

  4. Enhanced Adsorption of p-Arsanilic Acid from Water by Amine-Modified UiO-67 as Examined Using Extended X-ray Absorption Fine Structure, X-ray Photoelectron Spectroscopy, and Density Functional Theory Calculations.

    Science.gov (United States)

    Tian, Chen; Zhao, Jian; Ou, Xinwen; Wan, Jieting; Cai, Yuepeng; Lin, Zhang; Dang, Zhi; Xing, Baoshan

    2018-03-20

    p-Arsanilic acid ( p-ASA) is an emerging organoarsenic pollutant comprising both inorganic and organic moieties. For the efficient removal of p-ASA, adsorbents with high adsorption affinity are urgently needed. Herein, amine-modified UiO-67 (UiO-67-NH 2 ) metal-organic frameworks (MOFs) were synthesized, and their adsorption affinities toward p-ASA were 2 times higher than that of the pristine UiO-67. Extended X-ray absorption fine structure (EXAFS), X-ray photoelectron spectroscopy (XPS), and density functional theory (DFT) calculation results revealed adsorption through a combination of As-O-Zr coordination, hydrogen bonding, and π-π stacking, among which As-O-Zr coordination was the dominant force. Amine groups played a significant role in enhancing the adsorption affinity through strengthening the As-O-Zr coordination and π-π stacking, as well as forming new adsorption sites via hydrogen bonding. UiO-67-NH 2 s could remove p-ASA at low concentrations (<5 mg L -1 ) in simulated natural and wastewaters to an arsenic level lower than that of the drinking water standard of World Health Organization (WHO) and the surface water standard of China, respectively. This work provided an emerging and promising method to increase the adsorption affinity of MOFs toward pollutants containing both organic and inorganic moieties, via modifying functional groups based on the pollutant structure to achieve synergistic adsorption effect.

  5. X-ray spectroscopy from fusion plasmas

    International Nuclear Information System (INIS)

    Glenzer, S H.

    1998-01-01

    Our understanding of laser energy coupling into laser-driven inertial confinement fusion targets largely depends on our ability to accurately measure and simulate the plasma conditions in the underdense corona and in high density capsule implosions. X-ray spectroscopy is an important technique which has been applied to measure the total absorption of laser energy into the fusion target, the fraction of laser energy absorbed by hot electrons, and the conditions in the fusion capsule in terms of density and temperature. These parameters provide critical benchmarking data for performance studies of the fusion target and for radiation-hydrodynamic and laser-plasma interaction simulations. Using x-ray spectroscopic techniques for these tasks has required its application to non-standard conditions where kinetics models have not been extensively tested. In particular, for the conditions in high density implosions, where electron temperatures achieve 1 - 2 keV and electron densities reach 10 24 cm -3 evolving on time scales of 21 cm -3 and which am independently diagnosed with Thomson scattering and stimulated Raman scattering. We find that kinetics modeling is in good agreement with measured intensities of the dielectronic satellites of the He-β line (n= l-3) of Ar XVII. Applying these findings to the experimental results of capsule implosions provides additional evidence of temperature gradients at peak compression

  6. Photo-Darkening Kinetics and Structural Anisotropic Modifications in the Chalcogenide Glass Arsenic Trisulfide: a Study of Kinetic X-Ray Absorption Spectroscopy

    Science.gov (United States)

    Lee, Jay Min

    1990-08-01

    The purpose of the study is to investigate the mechanisms involved with photo-induced atomic structural modifications in the chalcogenide glass As_2 S_3. This glass exhibits the reversible effects of photo-darkening followed by thermal bleaching. We observed the time behavior of photo-induced properties under the influence of linearly polarized band -gap light. In a macroscopic optical investigation, we monitor optical changes in the photo-darkening process, and in a local structural probe we study kinetic (or time -resolved dispersive) x-ray absorption spectroscopy. Our observations center on kinetic phenomena and structural modifications induced by polarized excitation of lone-pair orbitals in the chalcogenide glass. Experimental results include the following observations: (i) The polarity of the optically induced anisotropy is critically dependent on the intensity and the polarization of the band-gap irradiation beam. (ii) The near edge peak height in x-ray absorption spectra shows subtle but sensitive change during the photo-darkening process. (iii) Photon intensity dependent dichroic kinetics reflect a connection between the optically probed macroscopic property and the x-ray probed local anisotropic structure. Analysis of the x-ray absorption results includes a computer simulation of the polarized absorption spectra. These results suggest that specific structural units tend to orient themselves with respect to the photon polarization. A substantial part of the analysis involves a major effort in dealing with the x-ray kinetic data manipulation and the experimental difficulties caused by a synchrotron instability problem. Based on our observations, we propose a possible mechanism for the observed photo-structural modifications. Through a model of computer relaxed photo-darkening kinetics, we support the notion that a twisting of a specific intermediate range order structure is responsible for local directional variations and global network distortions. In the

  7. Revisiting the localization of Zn2+ cations sorbed on pathological apatite calcifications made through X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Bazin, D.; Carpentier, X.; Brocheriou, I.; Dorfmuller, P.; Aubert, S.; Chappard, C.; Thiaudiere, D.; Reguer, S.; Waychunas, G.; Jungers, P.; Daudon, M.

    2009-04-01

    The role of oligo-elements such as Zn in the genesis of pathological calcifications is widely debated in the literature. An essential element of discussion is given by their localization either at the surface or within the Ca apatite crystalline network. To determine the localization, X-ray absorption experiments have been performed at SOLEIL. The Exafs results suggest that Zn atoms, present in the Zn{sup 2+} form, are bound to about 4 O atoms at a distance of 2.00{angstrom}, while the interatomic distance R{sub CaO} ranges between 2.35 {angstrom} and 2.71 {angstrom}. Taking into account the content of Zn (around 1000 ppm) and the difference in ionic radius between Zn{sup 2+} (0.074 nm) and Ca{sup 2+} (0.099 nm), a significant longer interatomic distance would be expected in the case of Zn replacing Ca within the apatite crystalline network. We thus conclude that Zn atoms are localized at the surface and not in the apatite nanocrystal structure. Such structural result has essential biological implications for at least two reasons. Some oligoelements have a marked effect on the transformation of chemical phases, and may modify the morphology of crystals. These are both major issues because, in the case of kidney stones, the medical treatment depends strongly on the precise chemical phase and on the morphology of the biological entities at both macroscopic and mesoscopic scales.

  8. Characterization of selenium in UO2 spent nuclear fuel by micro X-ray absorption spectroscopy and its thermodynamic stability.

    Science.gov (United States)

    Curti, E; Puranen, A; Grolimund, D; Jädernas, D; Sheptyakov, D; Mesbah, A

    2015-10-01

    Direct disposal of spent nuclear fuel (SNF) in deep geological formations is the preferred option for the final storage of nuclear waste in many countries. In order to assess to which extent radionuclides could be released to the environment, it is of great importance to understand how they are chemically bound in the waste matrix. This is particularly important for long-lived radionuclides such as (79)Se, (129)I, (14)C or (36)Cl, which form poorly sorbing anionic species in water and therefore migrate without significant retardation through argillaceous repository materials and host rocks. We present here X-ray absorption spectroscopic data providing evidence that in the investigated SNF samples selenium is directly bound to U atoms as Se(-II) (selenide) ion, probably replacing oxygen in the cubic UO2 lattice. This result is corroborated by a simple thermodynamic analysis, showing that selenide is the stable form of Se under reactor operation conditions. Because selenide is almost insoluble in water, our data indirectly explain the unexpectedly low release of Se in short-term aqueous leaching experiments, compared to iodine or cesium. These results have a direct impact on safety analyses for potential nuclear waste repository sites, as they justify assuming a small fractional release of selenium in performance assessment calculations.

  9. Electronic charge transfer in cobalt doped fullerene thin films and effect of energetic ion impacts by x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Thakur, P.; Kumar, Amit; Gautam, S.; Chae, K.H.

    2011-01-01

    We report on the electronic charge transfer in cobalt doped fullerene thin films by means of near-edge x-ray-absorption fine structure (NEXAFS) spectroscopy measurement. Co-doped fullerene films were prepared by co-deposition technique and subjected to energetic ion irradiation (120 MeV Au) for possibly alignment or interconnect of randomly distributed metal particles. Polarization dependent NEXAFS spectra revealed the alignment of Co and C atoms along the irradiated ionic path. The structural changes in Co-doped as-deposited and ion irradiated fullerene films were investigated by means of Raman spectroscopy measurements. Downshift of pentagonal pinch mode A g (2) in Raman spectroscopy indicated the electronic charge transfer from Co atom to fullerene molecules, which is further confirmed by NEXAFS at C K-edge for Co-doped fullerene films.

  10. Arsenic K-edge X-ray absorption near-edge spectroscopy to determine oxidation states of arsenic of a coastal aquifer–aquitard system

    International Nuclear Information System (INIS)

    Wang, Ya; Jiao, Jiu Jimmy; Zhu, Sanyuan; Li, Yiliang

    2013-01-01

    Determination of oxidation states of solid-phase arsenic in bulk sediments is a valuable step in the evaluation of its bioavailability and environmental fate in deposits, but is difficult when the sediments have low arsenic contents and heterogeneous distribution of arsenic species. As K-edge X-ray absorption near-edge spectroscopy (XANES) was used to determine quantitatively the oxidation states of arsenic in sediments collected from different depths of boreholes in the Pearl River Delta, China, where the highest aquatic arsenic concentration is 161.4 μg/L, but the highest solid arsenic content only 39.6 mg/kg. The results demonstrated that XANES is efficient in determining arsenic oxidation states of the sediments with low arsenic contents and multiple arsenic species. The study on the high-resolution vertical variations of arsenic oxidation states also indicated that these states are influenced strongly by groundwater activities. With the help of geochemical data, solid arsenic speciation, toxicity and availability were further discussed. -- Highlights: •XANES is efficient in determining arsenic oxidation states of the bulk sediments. •Distribution of arsenic oxidation states is consistent with geochemical conditions. •Arsenic oxidation states are influenced strongly by groundwater activities. -- As K-edge X-ray absorption near-edge spectroscopy is efficient in determining arsenic oxidation states of the bulk sediments with low arsenic contents and heterogeneous distribution of arsenic species

  11. A feasibility study on oxidation state of arsenic in cut tobacco, mainstream cigarette smoke and cigarette ash by X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Liu, C.; Hu, J.; McAdam, K.G.

    2009-01-01

    This work describes the application of synchrotron-based X-ray Absorption Near-Edge Structure spectroscopy to study the oxidation state of arsenic in cigarette mainstream smoke, cut tobacco and cigarette ash. The level of arsenic in the total particulate matter of the smoke is approximately 1 ppm for the standard research reference cigarette 2R4F and its replacement 3R4F. Smoke particulate samples collected by a conventional glass-fiber membrane (commercially known as Cambridge filter pad) and a jet-impaction method were analyzed and compared. In addition smoke particulate samples were aged either at ambient temperature or at 195 K. X-ray Absorption Near-Edge Structure spectroscopy results revealed that the cut tobacco powder and cigarette ash contained almost exclusively As V . The smoke particulate samples however contained a mixture of As III and As V . The As V in the smoke particulate was reduced to As III upon aging. Stabilizing the smoke particulate matter at 195 K by solid CO 2 slowed down this aging reaction and revealed a higher percentage of As V . This behavior is consistent with the redox properties of the arsenic species and the smoke particulate matrix.

  12. Hole distribution in (Sr, Ca, Y, La)14Cu24O41 compounds studies by x-ray absorption and emission spectroscopy

    International Nuclear Information System (INIS)

    Kabasawa, Eiki; Nakamura, Jin; Yamada, Nobuyoshi; Kuroki, Kazuhiko; Yamazaki, Hisashi; Watanabe, Masamitsu; Denlinger, Jonathan D.; Shin, Shik; Perera, Rupert C.C.

    2008-01-01

    The polarization dependence of soft x-ray absorption spectroscopy (XAS) and x-ray emission spectroscopy (XES) near the O 1s absorption edge was measured on two-leg ladder single-crystalline samples of (Sr, Ca, Y, La) 14 Cu 24 O 41 (14-24-41). The hole distributions in 14-24-41 compounds are determined by polarization analysis. For samples with less than or equal to 5 holes/chemical formula (c.f.), all holes reside on the edge-shared chain layer. In the case of Sr 14-x Ca x Cu 24 O 41 (6 holes/c.f.), there is approximately one hole on the two-leg ladder layer, with about five holes remaining on the edge-shared chain layer. By Ca substitution for Sr in the Sr 14-x Ca x Cu 24 O 41 samples, 0.3 holes transfer from the edge-shared chain to the two-leg ladder layer. It is possible that some of the holes on the two-leg ladder layer move from the rung sites to the leg sites upon Ca substitution. (author)

  13. Polarized X-ray absorption spectroscopy of single-crystal Mn(V) complexes relevant to the oxygen-evolving complex of photosystem II

    DEFF Research Database (Denmark)

    Yano, Junko; Robblee, John; Pushkar, Yulia

    2007-01-01

    High-valent Mn-oxo species have been suggested to have a catalytically important role in the water splitting reaction which occurs in the Photosystem II membrane protein. In this study, five- and six-coordinate mononuclear Mn(V) compounds were investigated by polarized X-ray absorption spectroscopy...... structure of the metal site was then studied by measuring the polarization dependence of X-ray absorption near-edge spectroscopy (XANES) pre-edge spectra (1s to 3d transition) and comparing with the results of density functional theory (DFT) calculations. The Mn(V)-nitrido compound, in which the manganese......-edge peak. This component was interpreted as a 1s to 3d(xz,yz) transition with 4px,y mixing, due to the displacement of the Mn atom out of the equatorial plane. The XANES results have been correlated to DFT calculations, and the spectra have been simulated using a TD (time-dependent)-DFT approach...

  14. UV-Photochemistry of the Disulfide Bond: Evolution of Early Photoproducts from Picosecond X-ray Absorption Spectroscopy at the Sulfur K-Edge.

    Science.gov (United States)

    Ochmann, Miguel; Hussain, Abid; von Ahnen, Inga; Cordones, Amy A; Hong, Kiryong; Lee, Jae Hyuk; Ma, Rory; Adamczyk, Katrin; Kim, Tae Kyu; Schoenlein, Robert W; Vendrell, Oriol; Huse, Nils

    2018-05-30

    We have investigated dimethyl disulfide as the basic moiety for understanding the photochemistry of disulfide bonds, which are central to a broad range of biochemical processes. Picosecond time-resolved X-ray absorption spectroscopy at the sulfur K-edge provides unique element-specific insight into the photochemistry of the disulfide bond initiated by 267 nm femtosecond pulses. We observe a broad but distinct transient induced absorption spectrum which recovers on at least two time scales in the nanosecond range. We employed RASSCF electronic structure calculations to simulate the sulfur-1s transitions of multiple possible chemical species, and identified the methylthiyl and methylperthiyl radicals as the primary reaction products. In addition, we identify disulfur and the CH 2 S thione as the secondary reaction products of the perthiyl radical that are most likely to explain the observed spectral and kinetic signatures of our experiment. Our study underscores the importance of elemental specificity and the potential of time-resolved X-ray spectroscopy to identify short-lived reaction products in complex reaction schemes that underlie the rich photochemistry of disulfide systems.

  15. A combined DFT and restricted open-shell configuration interaction method including spin-orbit coupling: Application to transition metal L-edge X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Roemelt, Michael; Maganas, Dimitrios; Neese, Frank [Max-Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Muelheim an der Ruhr (Germany); DeBeer, Serena [Max-Planck Institute for Chemical Energy Conversion, Stiftstrasse 34-36, D-45470 Muelheim an der Ruhr (Germany); Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853 (United States)

    2013-05-28

    A novel restricted-open-shell configuration interaction with singles (ROCIS) approach for the calculation of transition metal L-edge X-ray absorption spectra is introduced. In this method, one first calculates the ground state and a number of excited states of the non-relativistic Hamiltonian. By construction, the total spin is a good quantum number in each of these states. For a ground state with total spin S excited states with spin S Prime = S, S - 1, and S + 1 are constructed. Using Wigner-Eckart algebra, all magnetic sublevels with M{sub S}= S, Horizontal-Ellipsis , -S for each multiplet of spin S are obtained. The spin-orbit operator is represented by a mean-field approximation to the full Breit-Pauli spin-orbit operator and is diagonalized over this N-particle basis. This is equivalent to a quasi-degenerate treatment of the spin-orbit interaction to all orders. Importantly, the excitation space spans all of the molecular multiplets that arise from the atomic Russell-Saunders terms. Hence, the method represents a rigorous first-principles approach to the complicated low-symmetry molecular multiplet problem met in L-edge X-ray absorption spectroscopy. In order to gain computational efficiency, as well as additional accuracy, the excitation space is restricted to single excitations and the configuration interaction matrix is slightly parameterized in order to account for dynamic correlation effects in an average way. To this end, it is advantageous to employ Kohn-Sham rather than Hartree-Fock orbitals thus defining the density functional theory/ROCIS method. However, the method can also be used in an entirely non-empirical fashion. Only three global empirical parameters are introduced and have been determined here for future application of the method to any system containing any transition metal. The three parameters were carefully calibrated using the L-edge X-ray absorption spectroscopy spectra of a test set of coordination complexes containing first row

  16. The silicon neighborhood across the a-Si:H to {mu}c-Si transition by X-ray absorption spectroscopy (XAS)

    Energy Technology Data Exchange (ETDEWEB)

    Tessler, Leandro R.; Wang Qi; Branz, Howard M

    2003-04-22

    We report a synchrotron X-ray absorption spectroscopy study of the average neighborhood of Si near the transition from a-Si:H to {mu}c-Si on wedge-shaped samples prepared by hot-wire CVD in a chamber using a movable shutter. The thickness of the wedge varies from 30 to 160 nm. Nucleation of {mu}c-Si occurs at a critical thickness of approximately 100 nm. X-Ray absorption was measured at the Si K-edge (1.84 keV) by total electron photoemission yield. The absorption oscillations in the EXAFS region are very similar to all along the wedge. Analysis indicates an average tetrahedral first neighbor shell with radial disorder decreasing with crystallization. In the near-edge (XANES) region multiple scattering effects appear at the onset of crystallinity. Unlike single crystal silicon, these effects involve only double scattering within the first neighbor shell, indicating an ill-formed second shell in {mu}c-Si.

  17. X-ray emission spectroscopy. X-ray fluorescence

    International Nuclear Information System (INIS)

    Despujols, J.

    1992-01-01

    Principles of X-ray emission spectrometry are first recalled, then wave-length dispersive and energy dispersive X-ray fluorescence spectrometer are described. They are essentially designed for qualitative and quantitative analysis of elements (Z>10). Sample preparation, calibration, corrections, interferences, accuracy are reviewed. Examples of use in different industries are given. (71 refs.)

  18. Excited state electron and energy relays in supramolecular dinuclear complexes revealed by ultrafast optical and X-ray transient absorption spectroscopy.

    Science.gov (United States)

    Hayes, Dugan; Kohler, Lars; Hadt, Ryan G; Zhang, Xiaoyi; Liu, Cunming; Mulfort, Karen L; Chen, Lin X

    2018-01-28

    The kinetics of photoinduced electron and energy transfer in a family of tetrapyridophenazine-bridged heteroleptic homo- and heterodinuclear copper(i) bis(phenanthroline)/ruthenium(ii) polypyridyl complexes were studied using ultrafast optical and multi-edge X-ray transient absorption spectroscopies. This work combines the synthesis of heterodinuclear Cu(i)-Ru(ii) analogs of the homodinuclear Cu(i)-Cu(i) targets with spectroscopic analysis and electronic structure calculations to first disentangle the dynamics at individual metal sites by taking advantage of the element and site specificity of X-ray absorption and theoretical methods. The excited state dynamical models developed for the heterodinuclear complexes are then applied to model the more challenging homodinuclear complexes. These results suggest that both intermetallic charge and energy transfer can be observed in an asymmetric dinuclear copper complex in which the ground state redox potentials of the copper sites are offset by only 310 meV. We also demonstrate the ability of several of these complexes to effectively and unidirectionally shuttle energy between different metal centers, a property that could be of great use in the design of broadly absorbing and multifunctional multimetallic photocatalysts. This work provides an important step toward developing both a fundamental conceptual picture and a practical experimental handle with which synthetic chemists, spectroscopists, and theoreticians may collaborate to engineer cheap and efficient photocatalytic materials capable of performing coulombically demanding chemical transformations.

  19. X-ray Absorption Spectroscopy of the Zinc-Binding Sites in the Class B2 Metallo-B-lactamsase ImiS from Aeromonas veronii bv. sobria

    Energy Technology Data Exchange (ETDEWEB)

    Costello,A.; Sharma, N.; Yang, K.; Crowder, M.; Tierney, D.

    2006-01-01

    X-ray absorption spectroscopy was used to investigate the metal-binding sites of ImiS from Aeromonas veronii bv. sobria in catalytically active (1-Zn), product-inhibited (1-Zn plus imipenem), and inactive (2-Zn) forms. The first equivalent of zinc(II) was found to bind to the consensus Zn{sub 2} site. The reaction of 1-Zn ImiS with imipenem leads to a product-bound species, coordinated to Zn via a carboxylate group. The inhibitory binding site of ImiS was examined by a comparison of wild-type ImiS with 1 and 2 equiv of bound zinc. 2-Zn ImiS extended X-ray absorption fine structure data support a binding site that is distant from the active site and contains both one sulfur donor and one histidine ligand. On the basis of the amino acid sequence of ImiS and the crystal structure of CphA [Garau et al. (2005) J. Mol. Biol. 345, 785-795], we propose that the inhibitory binding site is formed by M146, found on the B2-distinct {alpha}3 helix, and H118, a canonical Zn{sub 1} ligand, proposed to help activate the nucleophilic water. The mutation of M146 to isoleucine abolishes metal inhibition. This is the first characterization of ImiS with the native metal Zn and establishes, for the first time, the location of the inhibitory metal site.

  20. In Situ Solid-State Reactions Monitored by X-ray Absorption Spectroscopy: Temperature-Induced Proton Transfer Leads to Chemical Shifts.

    Science.gov (United States)

    Stevens, Joanna S; Walczak, Monika; Jaye, Cherno; Fischer, Daniel A

    2016-10-24

    The dramatic colour and phase alteration with the solid-state, temperature-dependent reaction between squaric acid and 4,4'-bipyridine has been probed in situ with X-ray absorption spectroscopy. The electronic and chemical sensitivity to the local atomic environment through chemical shifts in the near-edge X-ray absorption fine structure (NEXAFS) revealed proton transfer from the acid to the bipyridine base through the change in nitrogen protonation state in the high-temperature form. Direct detection of proton transfer coupled with structural analysis elucidates the nature of the solid-state process, with intermolecular proton transfer occurring along an acid-base chain followed by a domino effect to the subsequent acid-base chains, leading to the rapid migration along the length of the crystal. NEXAFS thereby conveys the ability to monitor the nature of solid-state chemical reactions in situ, without the need for a priori information or long-range order. © 2016 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. X-ray film spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Rodriguez-Trelles, F.; Caputo, M.C. (Buenos Aires Univ. Nacional (Argentina). Lab. de Fisica del Plasma; Ministerio de Defensa, Buenos Aires (Argentina). DIGID)

    1982-02-15

    A multi-pinhole camera using film as a detector is described. Separation of variables in the master-curve sense leads to integral exposure equations which are solved by regularization. A filter-selection method is used to maximize the information content of a given set of measurements. Numerical simulation examples of the unfolding procedure are shown and the inversion error is evaluated. The essential role of absorption edges of filters and detectors for increasing the information content is emphasized and the method is compared with other absorption-edge techniques. A discussion of the present limitations of the method is given.

  2. Copper doped TiO2 nanoparticles characterized by X-ray absorption spectroscopy, total scattering, and powder diffraction--a benchmark structure-property study.

    Science.gov (United States)

    Lock, Nina; Jensen, Ellen M L; Mi, Jianli; Mamakhel, Aref; Norén, Katarina; Qingbo, Meng; Iversen, Bo B

    2013-07-14

    Metal functionalized nanoparticles potentially have improved properties e.g. in catalytic applications, but their precise structures are often very challenging to determine. Here we report a structural benchmark study based on tetragonal anatase TiO2 nanoparticles containing 0-2 wt% copper. The particles were synthesized by continuous flow synthesis under supercritical water-isopropanol conditions. Size determination using synchrotron PXRD, TEM, and X-ray total scattering reveals 5-7 nm monodisperse particles. The precise dopant structure and thermal stability of the highly crystalline powders were characterized by X-ray absorption spectroscopy and multi-temperature synchrotron PXRD (300-1000 K). The combined evidence reveals that copper is present as a dopant on the particle surfaces, most likely in an amorphous oxide or hydroxide shell. UV-VIS spectroscopy shows that copper presence at concentrations higher than 0.3 wt% lowers the band gap energy. The particles are unaffected by heating to 600 K, while growth and partial transformation to rutile TiO2 occur at higher temperatures. Anisotropic unit cell behavior of anatase is observed as a consequence of the particle growth (a decreases and c increases).

  3. X-ray spectroscopy an introduction

    CERN Document Server

    Agarwal, Bipin K

    1979-01-01

    Rontgen's discovery of X-rays in 1895 launched a subject which became central to the development of modern physics. The verification of many of the predic­ tions of quantum theory by X-ray spectroscopy in the early part of the twen­ tieth century stimulated great interest in thi's area, which has subsequently influenced fields as diverse as chemical physics, nuclear physics, and the study of the electronic properties of solids, and led to the development of techniques such as Auger, Raman, and X-ray photoelectron spectroscopy. The improvement of the theoretical understanding of the physics underlying X-ray spectroscopy has been accompanied by advances in experimental techniques, and the subject provides an instructive example of how progress on both these fronts can be mutually beneficial. This book strikes a balance between his­ torical description, which illustrates this symbiosis, and the discussion of new developments. The application of X-ray spectroscopic methods to the in­ vestigation of chemical b...

  4. Investigation of electronic states of infinite-layer SrFeO{sub 2} epitaxial thin films by X-ray photoemission and absorption spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Chikamatsu, Akira, E-mail: chikamatsu@chem.s.u-tokyo.ac.jp [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Matsuyama, Toshiya [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Hirose, Yasushi [Department of Chemistry, The University of Tokyo, Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan); Kumigashira, Hiroshi; Oshima, Masaharu [Department of Applied Chemistry, University of Tokyo, Tokyo 113-8656 (Japan); Hasegawa, Tetsuya [Department of Chemistry, University of Tokyo, Tokyo 113-0033 (Japan); Kanagawa Academy of Science and Technology (KAST), Kawasaki 213-0012 (Japan)

    2012-01-15

    Highlights: Black-Right-Pointing-Pointer Electronic states of infinite-layer SrFeO{sub 2} films have been experimentally observed. Black-Right-Pointing-Pointer Fe 3d states have higher densities of states in the valence-band region. Black-Right-Pointing-Pointer Three peaks derived from Fe 3d states were observed in the conduction-band region. Black-Right-Pointing-Pointer Indirect bandgap value was determined to be 1.3 eV. - Abstract: We investigated the electronic states of a single-crystal SrFeO{sub 2} epitaxial thin film in the valence-band and conduction-band regions using synchrotron-radiation X-ray photoemission and absorption spectroscopies. Fe 2p-3d resonant photoemission measurements revealed that the Fe 3d states have higher densities of states at binding energies of 3-5 eV and 5-8.5 eV in the valence-band region. The O K-edge X-ray absorption spectrum exhibited three peaks in the Fe 3d-derived conduction band hybridized with O 2p states; these can be assigned to Fe 3d{sub xy}, 3d{sub xz} + 3d{sub yz}, and 3d{sub x}{sup 2}{sub -y}{sup 2}. In addition, the indirect bandgap value of the SrFeO{sub 2} film was determined to be 1.3 eV by transmission and absorption spectroscopies.

  5. Pump-flow-probe x-ray absorption spectroscopy as a tool for studying aintermediate states of photocatalytic systems

    DEFF Research Database (Denmark)

    Smolentsev, Grigory; Guda, Alexander; Zhang, Xiaoyi

    2013-01-01

    -millimolar concentrations. A continuous wave laser is used for the photoexcitation, with the distance between laser and X-ray beams and velocity of liquid flow determining the time delay, while the focusing of both beams and the flow speed profile define the time resolution. This method is compared with the alternative...... measurement technique that utilizes a 1 kHz repetition rate laser and multiple X-ray probe pulses. Such an experiment was performed at beamline 11ID-D of the Advanced Photon Source. Advantages, limitations, and potential for improvement of the pump-flow-probe setup are discussed by analyzing the photon...... statistics. Both methods with Co K-edge probing were applied to the investigation of a cobaloxime-based photocatalytic reaction. The interplay between optimizing for efficient photoexcitation and time resolution as well and the effect of sample degradation for these two setups are discussed. © 2013 American...

  6. The advantages of soft X-rays and cryogenic spectrometers for measuring chemical speciation by X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Drury, Owen B. [Lawrence Livermore National Laboratory, Advanced Detector Group, 7000 East Ave., L-270, Livermore, CA 94550 (United States); UC Davis, Biophysics Graduate Group, 1 Shields Ave, CA 95616 (United States); LBNL, Advanced Biological and Environmental X-ray Facility, 1 Cyclotron Road, MS 6-2100, Berkeley, CA 92720 (United States); Friedrich, Stephan [Lawrence Livermore National Laboratory, Advanced Detector Group, 7000 East Ave., L-270, Livermore, CA 94550 (United States) and LBNL, Advanced Biological and Environmental X-ray Facility, 1 Cyclotron Road, MS 6-2100, Berkeley, CA 92720 (United States)]. E-mail: friedrich1@llnl.gov; George, Simon J. [LBNL, Advanced Biological and Environmental X-ray Facility, 1 Cyclotron Road, MS 6-2100, Berkeley, CA 92720 (United States); Cramer, Stephen P. [UC Davis, Biophysics Graduate Group, 1 Shields Ave, CA 95616 (United States); LBNL, Advanced Biological and Environmental X-ray Facility, 1 Cyclotron Road, MS 6-2100, Berkeley, CA 92720 (United States)

    2006-04-15

    We have built a 36-pixel high-resolution superconducting tunnel junction (STJ) soft X-ray spectrometer for chemical analysis of dilute metals by fluorescence-detected X-ray absorption spectroscopy (XAS) at the Advanced Light Source synchrotron. Soft X-ray absorption edges are preferred over traditional hard X-ray spectroscopy at the K-edges, since they have narrower natural linewidths and exhibit stronger chemical shifts. STJ detectors are preferred in the soft X-ray band over traditional Ge or grating spectrometers, since they have sufficient energy resolution to resolve transition metal L and M lines from light element K emission, and sufficient detection efficiency to measure the weak lines of dilute specimens within an acceptable time. We demonstrate the capabilities of our STJ spectrometer for chemical analysis with soft XAS measurements of molybdenum speciation on the Mo M{sub 4,5}-edges.

  7. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    KAUST Repository

    Hoffman, A. S.; Debefve, L. M.; Bendjeriou-Sedjerari, Anissa; Ould-Chikh, Samy; Bare, Simon R.; Basset, Jean-Marie; Gates, B. C.

    2016-01-01

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  8. Multi-edge X-ray absorption spectroscopy study of road dust samples from a traffic area of Venice using stoichiometric and environmental references

    Science.gov (United States)

    Valotto, Gabrio; Cattaruzza, Elti; Bardelli, Fabrizio

    2017-02-01

    The appropriate selection of representative pure compounds to be used as reference is a crucial step for successful analysis of X-ray absorption near edge spectroscopy (XANES) data, and it is often not a trivial task. This is particularly true when complex environmental matrices are investigated, being their elemental speciation a priori unknown. In this paper, an investigation on the speciation of Cu, Zn, and Sb based on the use of conventional (stoichiometric compounds) and non-conventional (environmental samples or relevant certified materials) references is explored. This method can be useful in when the effectiveness of XANES analysis is limited because of the difficulty in obtaining a set of references sufficiently representative of the investigated samples. Road dust samples collected along the bridge connecting Venice to the mainland were used to show the potentialities and the limits of this approach.

  9. Portable ultrahigh-vacuum sample storage system for polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo; Beniya, Atsushi; Isomura, Noritake [Toyota Central R& D Labs., Inc., Yokomichi 41-1, Nagakute, Aichi 480-1192 (Japan); Uehara, Hiromitsu; Asakura, Kiyotaka; Takakusagi, Satoru [Catalysis Research Center, Hokkaido University, Kita 21-10, Sapporo, Hokkaido 001-0021 (Japan); Nimura, Tomoyuki [AVC Co., Ltd., Inada 1450-6, Hitachinaka, Ibaraki 312-0061 (Japan)

    2016-03-15

    A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstrated by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.

  10. Electronic structure of Pt-Co cathode catalysts in membrane electrolyte assembly observed by X-ray absorption fine structure spectroscopy with different probing depth

    International Nuclear Information System (INIS)

    Kobayashi, M.; Hidai, S.; Niwa, H.; Harada, Y.; Oshima, M.; Ofuchi, H.; Nakamori, Y.; Aoki, T.

    2010-01-01

    Electronic structures of Pt-Co cathode and Pt-Ru anode catalysts in membrane electrolyte assemblies (MEAs) for polymer electrolyte fuel cell have been investigated using X-ray absorption near edge structure (XANES) spectroscopy, and the changes of electronic structures accompanied with degradation have been observed by comparison between spectra obtained by fluorescence-yield (FY) and conversion-electron-yield (CEY) methods, probing depths of which are several hundreds μm and ∼100 nm, respectively. The Co K XANES spectra of the as-fabricated MEA show that the Co atoms in the cathode are metallic and oxidized Co ions exist at the interface between the cathode and electrolyte. The spectra of the long-time operated MEA suggest that the oxidation of Co makes progress with degradation of the cathode catalysts. In contrast to the Co K XANES spectra, the line shape of the Ru K XANES spectra is unchanged even after the long-time operation.

  11. Transmission and fluorescence X-ray absorption spectroscopy cell/flow reactor for powder samples under vacuum or in reactive atmospheres

    KAUST Repository

    Hoffman, A. S.

    2016-07-26

    X-ray absorption spectroscopy is an element-specific technique for probing the local atomic-scale environment around an absorber atom. It is widely used to investigate the structures of liquids and solids, being especially valuable for characterization of solid-supported catalysts. Reported cell designs are limited in capabilities—to fluorescence or transmission and to static or flowing atmospheres, or to vacuum. Our goal was to design a robust and widely applicable cell for catalyst characterizations under all these conditions—to allow tracking of changes during genesis and during operation, both under vacuum and in reactive atmospheres. Herein, we report the design of such a cell and a demonstration of its operation both with a sample under dynamic vacuum and in the presence of gases flowing at temperatures up to 300 °C, showing data obtained with both fluorescence and transmission detection. The cell allows more flexibility in catalyst characterization than any reported.

  12. Mechanism of Selenite Removal by a Mixed Adsorbent Based on Fe–Mn Hydrous Oxides Studied Using X-ray Absorption Spectroscopy

    KAUST Repository

    Chubar, Natalia

    2014-11-18

    © 2014 American Chemical Society. Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3 2- trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

  13. Mechanism of Selenite Removal by a Mixed Adsorbent Based on Fe–Mn Hydrous Oxides Studied Using X-ray Absorption Spectroscopy

    KAUST Repository

    Chubar, Natalia; Gerda, Vasyl; Szlachta, Małgorzata

    2014-01-01

    © 2014 American Chemical Society. Selenium cycling in the environment is greatly controlled by various minerals, including Mn and Fe hydrous oxides. At the same time, such hydrous oxides are the main inorganic ion exchangers suitable (on the basis of their chemical nature) to sorb (toxic) anions, separating them from water solutions. The mechanism of selenite adsorption by the new mixed adsorbent composed of a few (amorphous and crystalline) phases [maghemite, MnCO3, and X-ray amorphous Fe(III) and Mn(III) hydrous oxides] was studied by extended X-ray absorption fine structure (EXAFS) spectroscopy [supported by Fourier transform infrared (FTIR) and X-ray diffraction (XRD) data]. The complexity of the porous adsorbent, especially the presence of the amorphous phases of Fe(III) and Mn(III) hydrous oxides, is the main reason for its high selenite removal performance demonstrated by batch and column adsorption studies shown in the previous work. Selenite was bound to the material via inner-sphere complexation (via oxygen) to the adsorption sites of the amorphous Fe(III) and Mn(III) oxides. This anion was attracted via bidentate binuclear corner-sharing coordination between SeO3 2- trigonal pyramids and both FeO6 and MnO6 octahedra; however, the adsorption sites of Fe(III) hydrous oxides played a leading role in selenite removal. The contribution of the adsorption sites of Mn(III) oxide increased as the pH decreased from 8 to 6. Because most minerals have a complex structure (they are seldom based on individual substances) of various crystallinity, this work is equally relevant to environmental science and environmental technology because it shows how various solid phases control cycling of chemical elements in the environment.

  14. Superconductive junctions for x-ray spectroscopy

    International Nuclear Information System (INIS)

    Grand, J.B. le; Bruijn, M.P.; Frericks, M.; Korte, P.A.J. de; Houwman, E.P.; Flokstra, J.

    1992-01-01

    Biasing of SIS-junctions for the purpose of high energy resolution x-ray detection is complicated by the presence of a DC Josephson current and AC Josephson current resonances, so that a large magnetic field is normally used for the suppression of these Josephson features. A transimpedance amplifier is proposed for biasing and signal amplification at low magnetic field. X-ray spectroscopy detectors for astronomy require a high detection efficiency in the 0.5-10 keV energy band and a reasonable (∼1 cm 2 ) detector area. Calculations on absorber-junctions combinations which might meet these requirements are presented. (author) 9 refs.; 10 figs

  15. Characterizing the Solvated Structure of Photoexcited [Os(terpy2]2+ with X-ray Transient Absorption Spectroscopy and DFT Calculations

    Directory of Open Access Journals (Sweden)

    Xiaoyi Zhang

    2016-02-01

    Full Text Available Characterizing the geometric and electronic structures of individual photoexcited dye molecules in solution is an important step towards understanding the interfacial properties of photo-active electrodes. The broad family of “red sensitizers” based on osmium(II polypyridyl compounds often undergoes small photo-induced structural changes which are challenging to characterize. In this work, X-ray transient absorption spectroscopy with picosecond temporal resolution is employed to determine the geometric and electronic structures of the photoexcited triplet state of [Os(terpy2]2+ (terpy: 2,2′:6′,2″-terpyridine solvated in methanol. From the EXAFS analysis, the structural changes can be characterized by a slight overall expansion of the first coordination shell [OsN6]. DFT calculations supports the XTA results. They also provide additional information about the nature of the molecular orbitals that contribute to the optical spectrum (with TD-DFT and the near-edge region of the X-ray spectra.

  16. X-Ray Spectroscopy of Gold Nanoparticles

    Science.gov (United States)

    Nahar, Sultana N.; Montenegro, M.; Pradhan, A. K.; Pitzer, R.

    2009-06-01

    Inner shell transitions, such as 1s-2p, in heavy elements can absorb or produce hard X-rays, and hence are widely used in nanoparticles. Bio-medical research for cancer treatment has been using heavy element nanoparticles, embeded in malignant tumor, for efficient absorption of irradiated X-rays and leading emission of hard X-rays and energetic electrons to kill the surrounding cells. Ejection of a 1s electron during ionization of the element by absorption of a X-ray photon initiates the Auger cascades of emission of photons and electrons. We have investigated gold nanoparticles for the optimal energy range, below the K-edge (1s) ionization threshold, that corresponds to resonant absorption of X-rays with large attenuation coefficients, orders of magnitude higher over the background as well as to that at K-edge threshold. We applied these attenuation coefficients in Monte Carlo simulation to study the intensities of emission of photons and electrons by Auger cascades. The numerical experiments were carried out in a phantom of water cube with a thin layer, 0.1mm/g, of gold nanoparticles 10 cm inside from the surface using the well-known code Geant4. We will present results on photon and electron emission spectra from passing monochromatic X-ray beams at 67 keV, which is the resonant energy for resonant K_{α} lines, at 82 keV, the K-shell ionization threshold, and at 2 MeV where the resonant effect is non-existent. Our findings show a high peak in the gold nanoparticle absorption curve indicating complete absorption of radiation within the gold layer. The photon and electron emission spectra show resonant features. Acknowledgement: Partially supported by a Large Interdisciplinary Grant award of the Ohio State University and NASA APRA program (SNN). The computational work was carried out on the Cray X1 and Itanium 4 cluster at the Ohio Supercomputer Center, Columbus Ohio. "Resonant X-ray Irradiation of High-Z Nanoparticles For Cancer Theranostics" (refereed

  17. X-ray spectroscopy with EBIT

    International Nuclear Information System (INIS)

    Beiersdorfer, P.; Cauble, R.; Chen, M.; DelGrande, N.; Knapp, D.; Marrs, R.; Osterheld, A.; Reed, K.; Schneider, M.; Scofield, J.; Wong, K.; Vogel, D.; Zasadzinski, R.; Chantrenne, S.; Wargelin, B.

    1992-04-01

    X-ray spectroscopy with the Livermore electron beam ion traps provides data on a wide range of atomic physics issues including ionization, recombination, and excitation cross sections, identification of forbidden transitions, and contributions from relatively and quantum electrodynamics to the transition energies. Here we briefly discuss the source characteristics and x-ray instrumentation, and report measurements of the excitation cross sections of the Kα transitions in heliumlike Ti 20+ as a function of beam energy. The measurements allow detailed comparisons with theoretical predictions of the direct electron-impact excitation cross sections, resonance-excitation contributions, and the electron temperature dependence of the ratio of triplet and singlet lines. The results demonstrate the importance of such measurements for increasing the reliability of x-ray diagnostics of laboratory and astrophysical plasmas

  18. Hard X-ray photoemission spectroscopy

    International Nuclear Information System (INIS)

    Kobayashi, Keisuke

    2009-01-01

    Except in the very early stage of the development of X-ray photoemission spectroscopy (XPS) by Kai Siegbahn and his coworkers, the excitation sources for XPS studies have predominantly been the Al Kα and Mg Kα emission lines. The advent of synchrotron radiation sources opened up the possibility of tuning the excitation photon energy with much higher throughputs for photoemission spectroscopy, however the excitation energy range was limited to the vacuum ultra violet and soft X-ray regions. Over the past 5-6 years, bulk-sensitive hard X-ray photoemission spectroscopy using high-brilliance high-flux X-rays from third generation synchrotron radiation facilities has been developed. This article reviews the history of HXPES covering the period from Kai Siegbahn and his coworkers' pioneering works to the present, and describes the fundamental aspects, instrumentation, applications to solid state physics, applied physics, materials science, and industrial applications of HXPES. Finally, several challenging new developments which have been conducted at SPring-8 by collaborations among several groups are introduced.

  19. Local structure studies of Fe{sub 2}TeO{sub 6} using x-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Harishchandra, E-mail: singh85harish@gmail.com [Homi Bhabha National Institute, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Indus Synchrotron Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore-452013 (India); Yadav, A. K. [Atomic & Molecular Physics Division Bhabha Atomic Research Centre, Mumbai – 400 094 (India)

    2016-05-23

    In the present study, we have performed EXAFS measurements on powder samples of Fe{sub 2}TeO{sub 6} (FTO) to probe the local structure surrounding at the Fe site. The structural parameters (atomic coordination and lattice parameters) of FTO used for simulation of theoretical EXAFS spectra of the samples have been obtained from Rietveld refined structure on synchrotron X-ray Diffraction (SXRD) data. Quite similar and satisfactory structural parameters have been obtained from both the study, indicating goodness of synchrotron structural analysis over EXAFS analysis. SXRD and EXAFS results shows absence of any secondary phase proves current synthesis superior over reported techniques.

  20. Soft x-ray absorption spectra of ilmenite family.

    Science.gov (United States)

    Agui, A; Mizumaki, M; Saitoh, Y; Matsushita, T; Nakatani, T; Fukaya, A; Torikai, E

    2001-03-01

    We have carried out soft x-ray absorption spectroscopy to study the electronic structure of ilmenite family, such as MnTiO3, FeTiO3, and CoTiO3 at the soft x-ray beamline, BL23SU, at the SPring-8. The Ti and M L2,3 absorption spectra of MTiO3 (M=Mn, Fe, and Co) show spectra of Ti4+ and M2+ electron configurations, respectively. Except the Fe L2,3 spectrum, those spectra were understood within the O(h) symmetry around the transition metal ions. The Fe L3-edge spectrum clearly shows a doublet peak at the L3 edge, which is attributed to Fe2+ state, moreover the very high-resolution the L-edge spectra of transition metals show fine structures. The spectra of those ilmenites are compared.

  1. X-ray absorption spectroscopy as a tool investigating arsenic(III) and arsenic(V) sorption by an aluminum-based drinking-water treatment residual.

    Science.gov (United States)

    Makris, Konstantinos C; Sarkar, Dibyendu; Parsons, Jason G; Datta, Rupali; Gardea-Torresdey, Jorge L

    2009-11-15

    Historic applications of arsenical pesticides to agricultural land have resulted in accumulation of residual arsenic (As) in such soils. In situ immobilization represents a cost-effective and least ecological disrupting treatment technology for soil As. Earlier work in our laboratory showed that drinking-water treatment residuals (WTRs), a low-cost, waste by-product of the drinking-water treatment process exhibit a high affinity for As. Wet chemical experiments (sorption kinetics and desorption) were coupled with X-ray absorption spectroscopy measurements to elucidate the bonding strength and type of As(V) and As(III) sorption by an aluminum-based WTR. A fast (1h), followed by a slower sorption stage resulted in As(V) and As(III) sorption capacities of 96% and 77%, respectively. Arsenic desorption with a 5mM oxalate from the WTR was minimal, being always absorption spectroscopy data showed inner-sphere complexation between As and surface hydroxyls. Reaction time (up to 48h) had no effect on the initial As oxidation state for sorbed As(V) and As(III). A combination of inner-sphere bonding types occurred between As and Al on the WTR surface because mixed surface geometries and interatomic distances were observed.

  2. Precipitation of gold by the reaction of aqueous gold(III)-chloride with cyanobacteria at 25-80 C -- Studied by x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Lengke, M. F.; Ravel, B.; Fleet, M. E.; Wanger, G.; Gordon, R. A.; Southam, G.

    2007-01-01

    The mechanisms of gold precipitation by the interaction of cyanobacteria (Plectonema boryanum UTEX 485) and gold(III) chloride aqueous solutions (7.6 mmol/L final gold) have been studied at 25, 60, and 80 C, using both laboratory and real-time synchrotron radiation absorption spectroscopy experiments. Addition of aqueous gold(III) chloride to the cyanobacterial culture initially promoted the precipitation of amorphous gold(I) sulfide at the cell walls and finally caused the formation of octahedral (111) platelets (<1 to 6 (micro)m) of gold metal near cell surfaces and in solutions. X-ray absorption spectroscopy results confirmed that the reduction mechanism of gold(III) chloride to elemental gold by cyanobacteria involves the formation of an intermediate Au(I) species, gold(I) sulfide, with sulfur originating from cyanobacterial proteins, presumably cysteine or methionine. Although the bioreduction of gold(III) chloride to gold(I) sulfide was relatively rapid at all temperatures, the reaction rate increased with the increase in temperature. At the completion of the experiments, elemental gold was the major species present at all temperatures

  3. The interaction of copper ions with Staphylococcus aureus, Pseudomonas aeruginosa, and Escherichia coli: an X-ray absorption near-edge structure (XANES) spectroscopy study.

    Science.gov (United States)

    Zanzen, Ulrike; Bovenkamp-Langlois, Lisa; Klysubun, Wantana; Hormes, Josef; Prange, Alexander

    2018-04-01

    The antimicrobial properties of copper ions have been known for a long time. However, the exact mechanism of action of the transition metal on microorganisms has long been unclear. X-ray absorption near-edge structure (XANES) spectroscopy at the Cu K edge allows the determination of copper speciation in Staphylococcus aureus, Escherichia coli, and Pseudomonas aeruginosa that have been treated with Cu(II) and Cu(I) solutions. The death/inactivation of the bacteria was observed using plate counting and light microscopy. The Cu K-XANES spectra of the two Gram-negative bacteria are different than those of the Gram-positive strain. The results clearly show that the Cu + -S bond contributes to the antibacterial activity of copper, as in the case of silver. The detailed evaluation of the differentiated absorption spectra shows that Cu + (not Cu 2+ ) is the dominant ion that binds to the bacteria. Because Cu + is not the most common copper ion, copper is not as effective an antibacterial agent as silver, whose common valency is actually + 1. Any reaction of copper with phosphorus from the bacteria can be excluded after the evaluation of the absorption spectra.

  4. Modeling L2,3-Edge X-ray Absorption Spectroscopy with Real-Time Exact Two-Component Relativistic Time-Dependent Density Functional Theory.

    Science.gov (United States)

    Kasper, Joseph M; Lestrange, Patrick J; Stetina, Torin F; Li, Xiaosong

    2018-04-10

    X-ray absorption spectroscopy is a powerful technique to probe local electronic and nuclear structure. There has been extensive theoretical work modeling K-edge spectra from first principles. However, modeling L-edge spectra directly with density functional theory poses a unique challenge requiring further study. Spin-orbit coupling must be included in the model, and a noncollinear density functional theory is required. Using the real-time exact two-component method, we are able to variationally include one-electron spin-orbit coupling terms when calculating the absorption spectrum. The abilities of different basis sets and density functionals to model spectra for both closed- and open-shell systems are investigated using SiCl 4 and three transition metal complexes, TiCl 4 , CrO 2 Cl 2 , and [FeCl 6 ] 3- . Although we are working in the real-time framework, individual molecular orbital transitions can still be recovered by projecting the density onto the ground state molecular orbital space and separating contributions to the time evolving dipole moment.

  5. Local structure studies of Ti for SrTi.sup.16./sup.O.sub.3./sub. and SrTi.sup.18./sup.O.sub.3./sub. by advanced x-ray absorption spectroscopy data analysis

    Czech Academy of Sciences Publication Activity Database

    Anspoks, A.; Timoshenko, J.; Bocharov, D.; Purans, J.; Rocca, F.; Sarakovskis, A.; Trepakov, Vladimír; Dejneka, Alexandr; Itoh, M.

    2015-01-01

    Roč. 485, č. 1 (2015), s. 42-52 ISSN 0015-0193 R&D Projects: GA ČR GAP108/12/1941 Institutional support: RVO:68378271 Keywords : strontium titanate * quantum paraelectric * isotopic effect * X-ray absorption spectroscopy * local atomic structure * phase transitions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.491, year: 2015

  6. Neutron and X-ray Spectroscopy

    CERN Document Server

    Hippert, Françoise; Hodeau, Jean Louis; Lelièvre-Berna, Eddy; Regnard, Jean-René

    2006-01-01

    Neutron and X-Ray Spectroscopy delivers an up-to-date account of the principles and practice of inelastic and spectroscopic methods available at neutron and synchrotron sources, including recent developments. The chapters are based on a course of lectures and practicals (the HERCULES course) delivered to young scientists who require these methods in their professional careers. Each chapter, written by a leading specialist in the field, introduces the basic concepts of the technique and provides an overview of recent work. This volume, which focuses on spectroscopic techniques in synchrotron radiation and inelastic neutron scattering, will be a primary source of information for physicists, chemists and materials scientists who wish to acquire a basic understanding of these techniques and to discover the possibilities offered by them. Emphasizing the complementarity of the neutron and X-ray methods, this tutorial will also be invaluable to scientists already working in neighboring fields who seek to extend thei...

  7. Doped holes in edge-shared CuO.sub.2./sub. chains and the dynamic spectral weght transfer in X-ray absorption spectroscopy

    Czech Academy of Sciences Publication Activity Database

    Hu, Z.; Drechsler, S.L.; Málek, Jiří; Rosner, H.; Neudert, R.; Knupper, M.; Golden, M. S.; Fink, J.; Karpinski, J.; Kaindl, G.

    2002-01-01

    Roč. 59, č. 1 (2002), s. 135-141 ISSN 0295-5075 Institutional research plan: CEZ:AV0Z1010914 Keywords : X-ray absorption spectra * strongly correlated electron systems * heavy fermions * many-electron systems Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.360, year: 2002

  8. X-ray absorption spectroscopy of soybean lipoxygenase-1 : Influence of lipid hydroperoxide activation and lyophilization on the structure of the non-heme iron active site

    NARCIS (Netherlands)

    Vliegenthart, J.F.G.; Heijdt, L.M. van der; Feiters, M.C.; Navaratnam, S.; Nolting, H.-F.; Hermes, C.; Veldink, G.A.

    1992-01-01

    X-ray absorption spectra at the Fe K-edge of the non-heme iron site in Fe(II) as well as Fe(III) soybean lipoxygenase-1, in frozen solution or lyophilized, are presented; the latter spectra were obtained by incubation of the Fe(II) enzyme with its product hydroperoxide. An edge shift of about 23 eV

  9. The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy.

    Science.gov (United States)

    Armendariz, Veronica; Parsons, Jason G; Lopez, Martha L; Peralta-Videa, Jose R; Jose-Yacaman, Miguel; Gardea-Torresdey, Jorge L

    2009-03-11

    Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

  10. The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy

    International Nuclear Information System (INIS)

    Armendariz, Veronica; Parsons, Jason G; Lopez, Martha L; Peralta-Videa, Jose R; Gardea-Torresdey, Jorge L; Jose-Yacaman, Miguel

    2009-01-01

    Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

  11. Ultrafast dynamics of two copper bis-phenanthroline complexes measured by x-ray transient absorption spectroscopy

    DEFF Research Database (Denmark)

    Kelley, Matthew S.; Shelby, Megan L.; Mara, Michael W.

    2017-01-01

    have the general formula [Cu(I)(R)2]+, where R = 2,9-dimethyl-1,10-phenanthroline (dmp) and 2,9-diphenyl-1,10-phenanthroline disulfonic acid disodium salt (dpps). [Cu(I)(dmp)2]+ has methyl groups at the 2,9 positions of phenanthroline (phen) and adopts a pseudo-tetrahedral geometry. In contrast, [Cu......(I)(dpps)2]+ possesses two bulky phenyl-sulfonate groups attached to each phen ligand that force the molecule to adopt a flattened tetrahedral geometry in the ground state. Previously, optical transient absorption (OTA) and synchrotron based XTA experiments with 100 ps time resolution have been employed...

  12. Wavelength dispersive X-ray absorption fine structure imaging by parametric X-ray radiation

    International Nuclear Information System (INIS)

    Inagaki, Manabu; Sakai, Takeshi; Sato, Isamu; Hayakawa, Yasushi; Nogami, Kyoko; Tanaka, Toshinari; Hayakawa, Ken; Nakao, Keisuke

    2008-01-01

    The parametric X-ray radiation (PXR) generator system at Laboratory for Electron Beam Research and Application (LEBRA) in Nihon University is a monochromatic and coherent X-ray source with horizontal wavelength dispersion. The energy definition of the X-rays, which depends on the horizontal size of the incident electron beam on the generator target crystal, has been investigated experimentally by measuring the X-ray absorption near edge structure (XANES) spectra on Cu and CuO associated with conventional X-ray absorption imaging technique. The result demonstrated the controllability of the spectrum resolution of XANES by adjusting of the horizontal electron beam size on the target crystal. The XANES spectra were obtained with energy resolution of several eV at the narrowest case, which is in qualitative agreement with the energy definition of the PXR X-rays evaluated from geometrical consideration. The result also suggested that the wavelength dispersive X-ray absorption fine structure measurement associated with imaging technique is one of the promising applications of PXR. (author)

  13. Simulating Ru L3-edge X-ray absorption spectroscopy with time-dependent density functional theory: model complexes and electron localization in mixed-valence metal dimers.

    Science.gov (United States)

    Van Kuiken, Benjamin E; Valiev, Marat; Daifuku, Stephanie L; Bannan, Caitlin; Strader, Matthew L; Cho, Hana; Huse, Nils; Schoenlein, Robert W; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of Ru(II) and Ru(III) complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6](4-) and Ru(II) polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5M(II)-CN-Ru(III)(NH3)5](-) (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  14. Bonding properties of FCC-like Au 44 (SR) 28 clusters from X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.; Chevrier, Daniel M. [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.; Zeng, Chenjie [Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.; Jin, Rongchao [Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.; Zhang, Peng [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.

    2017-11-01

    Thiolate-protected gold clusters with precisely controlled atomic composition have recently emerged as promising candidates for a variety of applications because of their unique optical, electronic, and catalytic properties. The recent discovery of the Au44(SR)28 total structure is considered as an interesting finding in terms of the face-centered cubic (FCC)-like core structure in small gold-thiolate clusters. Herein, the unique bonding properties of Au44(SR)28 is analyzed using temperature-dependent X-ray absorption spectroscopy (XAS) measurements at the Au L3-edge and compared with other FCC-like clusters such as Au36(SR)24 and Au28(SR)20. A negative thermal expansion was detected for the Au–Au bonds of the metal core (the first Au–Au shell) and was interpreted based on the unique Au core structure consisting of the Au4 units. EXAFS fitting results from Au28(SR)20, Au36(SR)24, and Au44(SR)28 show a size-dependent negative thermal expansion behavior in the first Au–Au shell, further highlighting the importance of the Au4 units in determining the Au core bonding properties and shedding light on the growth mechanism of these FCC-like Au clusters.

  15. Passivity of 316L stainless steel in borate buffer solution studied by Mott-Schottky analysis, atomic absorption spectrometry and X-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Feng Zhicao; Cheng Xuequn; Dong Chaofang; Xu Lin; Li Xiaogang

    2010-01-01

    Research highlights: → The polarization curve of 316L SS possesses five turning potentials in passive region. → Films formed at turning potentials perform different electrochemical and semiconductor properties. → Dissolutions and regenerations of passive film at turning potentials are obtained by AAS and XPS. → Turning potentials appearing in passive region are ascribed to the changes of the compositions of the passive films. - Abstract: The passivity of 316L stainless steel in borate buffer solution has been investigated by Mott-Schottky, atomic absorption spectrometry (AAS) and X-ray photoelectron spectroscopy (XPS). The results indicate that the polarization curve in the passive region possesses several turning potentials (0 V SCE , 0.2 V SCE , 0.4 V SCE , 0.6 V SCE and 0.85 V SCE ). The passive films formed at turning potentials perform different electrochemical and semiconductor properties. Further, the compositions of the passive films formed at turning potentials are investigated. The results reasonably explain why these potentials appear in the passive region and why specimens perform different properties at turning potentials.

  16. X-ray absorption spectroscopy for characterisation of catalysts for PEM fuel cells; Roentgenabsorptionsspektroskopie zur Charakterisierung von Katalysatoren fuer die PEM-Brennstoffzelle

    Energy Technology Data Exchange (ETDEWEB)

    Koehl, G.

    2001-10-01

    The investigation of bimetallic nanoparticles is of great interest for the development of powerful anode catalysts in PEM fuel cells. The determination of their electronic and geometric structure is crucial for the optimization of the activity and selectivity in the fuel cell. Especially carbon supported PtRu particles have shown superior activity as anode catalysts due to their high CO tolerance. To state the reason on an atomic level, X-ray absorption spectroscopy (XAS) with synchrotron radiation has been used to examine several Pt and PtRu nanoparticle systems. They were either prepared on the basis of preformed PtRu alloy colloids stabilized by different surfactants or by chemical reduction of precursors, Na{sub 6}Pt(SO{sub 3}){sub 4} and Na{sub 6}Ru(SO{sub 3}){sub 4}. Although a PtRu interaction was observed in all systems, a nonstatistical distribution of Pt and Ru atoms in the nanoparticles could be verified. In additional investigations the reaction mechanism during the synthesis of an organometallic stabilized Pt colloid was examined. In-situ measurements revealed the formation of an hitherto unknown Pt complex as intermediate state prior to the nucleation of the particles. (orig)

  17. Dynamics of oxide growth on Pt nanoparticles electrodes in the presence of competing halides by operando energy dispersive X-Ray absorption spectroscopy

    KAUST Repository

    Minguzzi, Alessandro

    2018-03-17

    In this work we studied the kinetics of oxide formation and reduction on Pt nanoparticles in HClO4 in the absence and in the presence of Br− and Cl− ions. The study combines potential step methods (i.e. chronoamperometry and choronocoulometry) with energy dispersive X-ray absorption spectroscopy (ED-XAS), which in principle allows to record a complete XAS spectrum in the timescale of milliseconds. Here, the information on the charge state and on the atomic surrounding of the considered element provided by XAS was exploited to monitor the degree of occupancy of 5d states of Pt in the course of oxide formation and growth, and to elucidate the competing halide adsorption/desorption phenomena. Electrochemical methods and XAS agree on the validity of a log(t) depending growth of Pt oxide, that is significantly delayed in the presence of Cl− and Br− anions. In the proximity of formation of one monolayer, the growth is further slowed down.

  18. X-ray absorption spectroscopy on phosphoric-salt pellets. Determination of the geometric and electronic structure of metal-oxide doped sodium-phosphate glasses

    International Nuclear Information System (INIS)

    Brendebach, B.

    2004-02-01

    Sodium metaphosphate glasses doped with transition metal oxides show characteristic colors. X-ray absorption spectroscopy (XAS) investigations provide information whether the coloration stems from different electronic transitions or changes in the geometrical structure of the glasses. Even though the violet color of MnO y -doped glasses is considered as an evidence for Mn 3+ -ions, Mn K-XAS reveals that the majority of the manganese ions are in the oxidation state +II and have a mixed coordination of four and six oxygen atoms, respectively. The oxygen coordination around the nickel ions in NiO-doped glasses with different metall oxide concentrations is always six. The change of color from citreous to auburn with increasing nickel oxide content is attributed to a systematic change in the bonding characteristic from mainly ionic-like to a small but significant contribution of covalent-like bonding. Analysis of higher coordination shells provides no indication of the formation of metal oxide clusters. (orig.)

  19. Chlorine levels and species in fine and size resolved atmospheric particles by X-ray absorption near-edge structure spectroscopy analysis in Beijing, China.

    Science.gov (United States)

    Ouyang, Jie; Yang, Guo-Sheng; Ma, Ling-Ling; Luo, Min; Zheng, Lei; Huo, Qing; Zhao, Yi-Dong; Hu, Tian-Dou; Cai, Zhen-Feng; Xu, Dian-Dou

    2018-04-01

    An understanding of the species of chlorine is crucial in the metropolis-Beijing, which is suffering serious haze pollution with high frequency. Particulate Matters (PMs) with five different sizes were collected in Beijing from July 2009 to March 2016, and characterized non-destructively by X-ray absorption near edge structure spectroscopy. PM 2.5 contributed for the major PMs mass in spring and summer, PM 0.5-1.0 and PM 1.0-2.5 contributed for the major PMs mass in autumn and winter. The concentrations of the three chlorine species were in the order of inorganic chlorine (Cl inorg ) > aliphatic chlorine (Cl ali ) > aromatic chlorine (Cl aro ), indicating that Cl inorg constituted the primary chlorine fraction and less toxic Cl ali constituted the primary total organic chlorine (Cl ali  + Cl aro , abbreviated as Cl org ) in the PMs in Beijing. In addition, these three chlorine species exhibited identical seasonal variation in PM 2.5 : winter > autumn > spring > summer. Wet precipitation is an important factor to result in the lower mass concentrations of these three chlorine species in summer. The temporal variations of both size resolved PM mass concentrations and chlorine species concentrations suggested that the air pollution prevention and control in Beijing has just won initial success. Copyright © 2017 Elsevier Ltd. All rights reserved.

  20. Study of fission products (Cs, Ba, Mo, Ru) behaviour in irradiated and simulated nuclear fuels during severe accidents using X-ray absorption Spectroscopy, SIMS and EPMA

    International Nuclear Information System (INIS)

    Geiger, Ernesto

    2016-01-01

    The identification of Fission Products (FP) release mechanism from irradiated nuclear fuels during a severe accident is of main importance for the development of codes for the estimation of the source-term (nature and quantity of radionuclides released into the environment). among the many FP Ba, Cs, Mo and Ru present a particular interest, since they may interact with each other or other elements and thus affect their release. In the framework of this thesis, two work axes have been set up in order to identify, firstly, the chemical phases initially present before the accident and, secondly, their evolution during the accident itself. The experimental approach consisted in reproducing nuclear severe accidents conditions at laboratory scale using both irradiated fuels and model materials (natural UO_2 doped with 12 FP). The advantage of these latter is the possibility of using characterization methods such as X-ray absorption Spectroscopy which are not available for irradiated fuels. Three irradiated fuel samples have been studied, representative to an initial state (before the accident), to an intermediate stage (1773 K) and to an advanced stage (2873 K) of a nuclear severe accident. Regarding to model materials, many accident sequences have been carried out, from 573 to 1973 K. Experimental results have allowed to establish a new release mechanism, considering both reducing and oxidizing conditions during an accident. These results have also demonstrated the importance of model materials as a complement to irradiated nuclear fuels in the study of nuclear severe accidents. (author) [fr

  1. Structural evolution of fluorinated graphene upon molten-alkali treatment probed by X-ray absorption near-edge structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Liang, Xianqing, E-mail: lxq@gxu.edu.cn [Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China); Pan, Deyou; Lao, Ming; Liang, Shuiying [Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Huang, Dan; Zhou, Wenzheng; Guo, Jin [Guangxi Colleges and Universities Key Laboratory of Novel Energy Materials and Related Technology, College of Physics Science and Technology, Guangxi University, Nanning 530004 (China); Guangxi Collaborative Innovation Center of Structure and Property for New Energy and Materials, School of Material Science and Engineering, Guilin University of Electronic Technology, Guilin 541004 (China)

    2017-05-15

    Highlights: • Structural evolution of FG during the molten-alkali treatment was studied. • XANES results reveal the transformation of surface functional groups of HFG. • The local and electronic structure of HFG can be tuned by varying the alkali-FG ratio. - Abstract: The structural evolution of fluorinated graphene (FG) nanosheets upon molten-alkali treatment has been systematically investigated utilizing X-ray absorption near-edge structure (XANES) spectroscopy. It is found that the hydroxyl groups can progressively displace fluorine atoms to form covalent bonds to the graphene sheets under designed molten-alkali condition. The XANES spectra also reveal the formation of epoxide groups through intramolecular dehydration of neighbouring hydroxyl groups after substitution reaction. At high alkali-FG weight ratio, the restoration of the π-conjugated structure in graphene sheets can be observed due to the gradual decomposition of epoxide groups. Our experimental results indicate that the surface chemistry and electronic structure of hydroxyl-functionalized FG (HFG) can be readily tuned by varying the ratio of reactants.

  2. Monitoring the role of Mn and Fe in the As-removal efficiency of tetravalent manganese feroxyhyte nanoparticles from drinking water: An X-ray absorption spectroscopy study.

    Science.gov (United States)

    Pinakidou, F; Katsikini, M; Paloura, E C; Simeonidis, K; Mitraka, E; Mitrakas, M

    2016-09-01

    The implementation of amorphous tetravalent manganese feroxyhyte (TMFx) nanoparticles, prepared via co-precipitation synthesis, as an efficient As(V)-removal material is investigated using X-ray absorption fine structure (XAFS) spectroscopy at the Fe-, Mn- and As-K-edges. The optimum synthesis conditions and chemical composition of the TMFx adsorbent were determined by the degree of polymerization in the adsorbents' microstructure. Under synthesis into mildly acidic conditions, the change in the polymerization of the metal-oxyhydroxyl chains (metal=Fe, Mn) provides more adsorption sites at edges and corner sites in the bonding environment of Fe and Mn, respectively, thereby enhancing As uptake. After exposure to As-polluted water, similar microstructural changes related to As-bidentate and monodentate geometries are generated: As(V) preferentially occupies the high energy adsorption sites ((2)C complexes) available in the Mn-oxyhydroxyl groups and the low energy edge sites offered by Fe ((2)E complexes). It is revealed that optimum arsenic-removal by TMFx occurs into mildly acidic synthesis pH and for iron to manganese molar ratio equal to 3. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Dynamics of oxide growth on Pt nanoparticles electrodes in the presence of competing halides by operando energy dispersive X-Ray absorption spectroscopy

    KAUST Repository

    Minguzzi, Alessandro; Montagna, Linda; Falqui, Andrea; Vertova, Alberto; Rondinini, Sandra; Ghigna, Paolo

    2018-01-01

    In this work we studied the kinetics of oxide formation and reduction on Pt nanoparticles in HClO4 in the absence and in the presence of Br− and Cl− ions. The study combines potential step methods (i.e. chronoamperometry and choronocoulometry) with energy dispersive X-ray absorption spectroscopy (ED-XAS), which in principle allows to record a complete XAS spectrum in the timescale of milliseconds. Here, the information on the charge state and on the atomic surrounding of the considered element provided by XAS was exploited to monitor the degree of occupancy of 5d states of Pt in the course of oxide formation and growth, and to elucidate the competing halide adsorption/desorption phenomena. Electrochemical methods and XAS agree on the validity of a log(t) depending growth of Pt oxide, that is significantly delayed in the presence of Cl− and Br− anions. In the proximity of formation of one monolayer, the growth is further slowed down.

  4. An overview on the research of Sr2IrO4-based system probed by X-ray absorption spectroscopy

    Science.gov (United States)

    Cheng, Jie; Zhu, Chaomin; Ma, Jingyuan; Wang, Yu; Liu, Shengli

    2018-03-01

    Investigations of materials with 5d transition metal ions have opened up new paradigms in condensed-matter physics because of their large spin-orbit coupling (SOC) interactions. The typical compound is Sr2IrO4, which attracted much attention due to its similarities to the parent compound of high-Tc cuprate superconductor La2CuO4. Theoretical calculations predicted that the unconventional superconductivity can occur in carrier doped-Sr2IrO4 system. Until now, hundreds of experimental methods were devoted to investigate the carrier doping effect on Sr2IrO4. Synchrotron radiation-based X-ray absorption spectroscopy (XAS) made great contributions to the local lattice and electronic structure, and also the intimate relationship between the local structure and physical properties induced by carrier doping. The aim of this review is a short introduction to the progress of research on Sr2IrO4-based system probed by the unique technique — XAS, including the strength of the SOC, valence changes upon doping and even local lattice structure with atomic level for this Sr2IrO4-based family.

  5. Dopant activation in Sn-doped Ga{sub 2}O{sub 3} investigated by X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Siah, S. C., E-mail: sincheng@alum.mit.edu; Brandt, R. E.; Jaramillo, R.; Buonassisi, T., E-mail: buonassisi@mit.edu [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Lim, K. [SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025 (United States); Department of Materials Science and Engineering, Stanford University, Stanford, California 94305 (United States); Schelhas, L. T.; Toney, M. F. [SLAC National Accelerator Laboratory, Stanford Synchrotron Radiation Lightsource, Menlo Park, California 94025 (United States); Heinemann, M. D. [PVcomB, Helmholtz-Zentrum Berlin, 12489 Berlin (Germany); Chua, D.; Gordon, R. G. [Department of Chemistry Materials Science and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138 (United States); Wright, J.; Segre, C. U. [Physics Department and CSRRI, Illinois Institute of Technology, Chicago, Illinois 60616 (United States); Perkins, J. D. [National Renewable Energy Laboratory, Golden, Colorado 80401 (United States)

    2015-12-21

    Doping activity in both beta-phase (β-) and amorphous (a-) Sn-doped gallium oxide (Ga{sub 2}O{sub 3}:Sn) is investigated by X-ray absorption spectroscopy (XAS). A single crystal of β-Ga{sub 2}O{sub 3}:Sn grown using edge-defined film-fed growth at 1725 °C is compared with amorphous Ga{sub 2}O{sub 3}:Sn films deposited at low temperature (<300 °C). Our XAS analyses indicate that activated Sn dopant atoms in conductive single crystal β-Ga{sub 2}O{sub 3}:Sn are present as Sn{sup 4+}, preferentially substituting for Ga at the octahedral site, as predicted by theoretical calculations. In contrast, inactive Sn atoms in resistive a-Ga{sub 2}O{sub 3}:Sn are present in either +2 or +4 charge states depending on growth conditions. These observations suggest the importance of growing Ga{sub 2}O{sub 3}:Sn at high temperature to obtain a crystalline phase and controlling the oxidation state of Sn during growth to achieve dopant activation.

  6. Unexpected covalency from actinide 5f orbital interactions (An = Th, U, Np, Pu) determined from chlorine K-edge X-ray absorption spectroscopy and electronic structure theory

    International Nuclear Information System (INIS)

    Clark, D.L.; Batista, E.R.; Boland, K.S.

    2010-01-01

    We have employed Cl K-edge XAS and multiple levels of sophisticated electronic structure calculations on a series of simple octahedral light actinide (Th, U, Np, Pu) chloride salts, AnCl 6 n- in order to assess the relative roles of the valence 5f and 6d orbitals in chemical bonding. Chlorine K-edge X-ray absorption spectroscopy on AnCl 6 n- (An = Th, U, Np, Pu) systems indicates the presence of covalent interactions between both Cl 3p and An 5f and 6d orbitals, with the relative contributions changing across the series. Electronic structure calculations indicate the predominant covalent interactions are expected to occur through An-Cl bonding via t 1u and t 2u interactions with the An 5f orbitals, and through t 2g and e g interactions with An 6d orbitals. For the Cl K-edge data therefore, we expect bound state transitions from Cl 1s → e g (σ), t 2g (π), and t 1u (σ + π) orbitals. Qualitatively, the Cl K-edge data fulfills these expectations

  7. Ancient wood of the Acqualadrone rostrum: materials history through gas chromatography/mass spectrometry and sulfur X-ray absorption spectroscopy.

    Science.gov (United States)

    Frank, Patrick; Caruso, Francesco; Caponetti, Eugenio

    2012-05-15

    In 2008 the rostrum from an ancient warship was recovered from the Mediterranean near Acqualadrone, Sicily. To establish its provenance and condition, samples of black and brown rostrum wood were examined using sulfur K-edge X-ray absorption spectroscopy (XAS) and gas chromatography/mass spectrometry (GC/MS). GC/MS of pyrolytic volatiles yielded only guaiacyl derivatives, indicating construction from pinewood. A derivatized extract of black wood yielded forms of abietic acid and sandaracopimaric acid consistent with pine pitch waterproofing. Numerical fits to the sulfur K-edge XAS spectra showed that about 65% of the endogenous sulfur consisted of thiols and disulfides. Elemental sulfur was about 2% and 7% in black and brown wood, respectively, while pyritic sulfur was about 12% and 6%. About 2% of the sulfur in both wood types was modeled as trimethylsulfonium, possibly reflecting biogenic (dimethylsulfonio)propionate. High-valent sulfur was exclusively represented by sulfate esters, consistent with bacterial sulfotransferase activity. Traces of chloride were detected, but no free sulfate ion. In summary, the rostrum was manufactured of pine wood and subsequently waterproofed with pine pitch. The subsequent 2300 years included battle, foundering, and marine burial followed by anoxia, bacterial colonization, sulfate reduction, and mobilization of transition metals, which produced pyrite and copious appended sulfur functionality.

  8. The Ancient Wood of the Acqualadrone Rostrum: A Materials History Through GC-MS and Sulfur X-ray Absorption Spectroscopy

    Science.gov (United States)

    Frank, Patrick; Caruso, Francesco; Caponetti, Eugenio

    2012-01-01

    In 2008 the rostrum from an ancient warship was recovered from the Mediterranean near Acqualadrone, Sicily. To establish its provenance and condition, samples of black and brown rostrum wood were examined using sulfur K-edge x-ray absorption spectroscopy (XAS) and GC-MS. GC-MS of pyrolytic volatiles yielded only guaiacyl derivatives, indicating construction from pinewood. A derivatized extract of black wood yielded forms of abietic acid and sandaracopimaric acid consistent with pine pitch waterproofing. Numerical fits to the sulfur K-edge XAS spectra showed that about 65% of the endogenous sulfur consisted of thiols and disulfides. Elemental sulfur was about 2% and 7% in black and brown wood, respectively, while pyritic sulfur was about 12% and 6%. About 2% of the sulfur in both wood types was modeled as trimethylsulfonium, possibly reflecting biogenic dimethylsulfonio-propionate. High valent sulfur was exclusively represented by sulfate esters, consistent with bacterial sulfotransferase activity. Traces of chloride were detected, but no free sulfate ion. In summary, the rostrum was manufactured of pine wood and subsequently waterproofed with pine pitch. The subsequent 2300 years included battle, foundering, and marine burial followed by anoxia, bacterial colonization, sulfate reduction, and mobilization of transition metals, which produced pyrite and copious appended sulfur functionality. PMID:22545724

  9. In situ X-ray near-edge absorption spectroscopy investigation of the state of charge of all-vanadium redox flow batteries.

    Science.gov (United States)

    Jia, Chuankun; Liu, Qi; Sun, Cheng-Jun; Yang, Fan; Ren, Yang; Heald, Steve M; Liu, Yadong; Li, Zhe-Fei; Lu, Wenquan; Xie, Jian

    2014-10-22

    Synchrotron-based in situ X-ray near-edge absorption spectroscopy (XANES) has been used to study the valence state evolution of the vanadium ion for both the catholyte and anolyte in all-vanadium redox flow batteries (VRB) under realistic cycling conditions. The results indicate that, when using the widely used charge-discharge profile during the first charge process (charging the VRB cell to 1.65 V under a constant current mode), the vanadium ion valence did not reach V(V) in the catholyte and did not reach V(II) in the anolyte. Consequently, the state of charge (SOC) for the VRB cell was only 82%, far below the desired 100% SOC. Thus, such incompletely charged mix electrolytes results in not only wasting the electrolytes but also decreasing the cell performance in the following cycles. On the basis of our study, we proposed a new charge-discharge profile (first charged at a constant current mode up to 1.65 V and then continuously charged at a constant voltage mode until the capacity was close to the theoretical value) for the first charge process that achieved 100% SOC after the initial charge process. Utilizing this new charge-discharge profile, the theoretical charge capacity and the full utilization of electrolytes has been achieved, thus having a significant impact on the cost reduction of the electrolytes in VRB.

  10. Investigating the Geochemical Model for Molybdenum Mineralization in the JEB Tailings Management Facility at McClean Lake, Saskatchewan: An X-ray Absorption Spectroscopy Study.

    Science.gov (United States)

    Blanchard, Peter E R; Hayes, John R; Grosvenor, Andrew P; Rowson, John; Hughes, Kebbi; Brown, Caitlin

    2015-06-02

    The geochemical model for Mo mineralization in the JEB Tailings Management Facility (JEB TMF), operated by AREVA Resources Canada at McClean Lake, Saskatchewan, was investigated using X-ray Absorption Near-Edge Spectroscopy (XANES), an elemental-specific technique that is sensitive to low elemental concentrations. Twenty five samples collected during the 2013 sampling campaign from various locations and depths in the TMF were analyzed by XANES. Mo K-edge XANES analysis indicated that the tailings consisted primarily of Mo(6+) species: powellite (CaMoO4), ferrimolybdite (Fe2(MoO4)3·8H2O), and molybdate adsorbed on ferrihydrite (Fe(OH)3 - MoO4). A minor concentration of a Mo(4+) species in the form of molybdenite (MoS2) was also present. Changes in the Mo mineralization over time were inferred by comparing the relative amounts of the Mo species in the tailings to the independently measured aqueous Mo pore water concentration. It was found that ferrimolybdite and molybdate adsorbed on ferrihydrite initially dissolves in the TMF and precipitates as powellite.

  11. Study of apical oxygen atoms in a spin-ladder cuprate compound by X-ray absorption spectroscopy near the Cu K edge

    Energy Technology Data Exchange (ETDEWEB)

    Hatterer, C.J.; Eustache, B.; Collin, L.; Beuran, C.F.; Partiot, C.; Germain, P.; Xu, X.Z.; Lagues, M. [CNRS, Paris (France). Surfaces et Supraconducteurs; Michalowicz, A. [Laboratoire de Physique des Milieux Desordonnes, Universite Paris XII Val-de-Marne, 61 avenue du general de Gaulle, 94010, Creteil Cedex (France)]|[LURE, Universite Paris Sud, 91405, Orsay Cedex (France); Moscovici, J. [Laboratoire de Physique des Milieux Desordonnes, Universite Paris XII Val-de-Marne, 61 avenue du general de Gaulle, 94010, Creteil Cedex (France); Deville Cavellin, C. [CNRS, Paris (France). Surfaces et Supraconducteurs]|[Laboratoire d`Electronique, Universite Paris XII Val-de-Marne, 61 av. du general de Gaulle, 94010, Creteil Cedex (France); Traverse, A. [LURE, Universite Paris Sud, 91405, Orsay Cedex (France)

    1997-04-01

    The structure of high-T{sub c} superconducting cuprate compounds is based on CuO{sub 2} planes alternating with blocks that behave as charge reservoirs. The apical oxygen atoms which belong to these reservoirs are suspected to play a role in the mechanism of superconductivity. It thus seems necessary to measure the amount of apical oxygen atoms in various compounds, as a function of the superconducting properties. Polarisation dependent X-ray absorption spectroscopy (XAS) measurements were performed near the Cu K-edge on three types of phases. We collected information about the neighbourhood of the copper atom in the cuprate planes and in the direction perpendicular to these planes. Two of these phases have well known structures: Bi2212 in which copper atoms are on a pyramidal site and infinite layer phase, a square planar cuprate without apical oxygen. We used the obtained results as reference data to study a new copper-rich phase related to the spin-ladder series. (orig.)

  12. Characterization of the core-shell interaction of differently stabilized transition-metal nanoparticles by means of X-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Bucher, S.

    2002-05-01

    Transition metal nanoparticles with different surfactants were investigated using X-ray absorption spectroscopy (XAS) to obtain information about the interaction between metal core and protecting shell. For tetraalkylammoniumchloride stabilized Pd- and Co-colloids, a detailed model of the interaction between the metal core and the stabilizing shell could be established, in which chlorine is the connecting element between the metal core and the organic protection cover. Different lengths of the alkyl-chains can cause different equilibrium positions for the chlorine atoms. At aluminum-organic stabilized Pt-colloids, Al K-XANES and Pt L III -XAS were carried out. In this case, it turned out that aluminum is the connecting element between metal core and protection shell. After modification of the shell by connecting different molecules to the outside of the shell, rearrangements of the shell could be observed. In contrast to the surfactant stabilized systems discussed above, metallic covers, especially gold coatings, of Co-particles did not lead to a complete protection shell. In all cases, the cobalt in the nanoparticles was oxidized. A core shell structure could not be verified for any of the metallic stabilized colloids. (orig.)

  13. The structures of T6, T3R3 and R6 bovine insulin: combining X-ray diffraction and absorption spectroscopy

    DEFF Research Database (Denmark)

    Frankær, Christian Grundahl; Knudsen, Marianne Vad; Noren, Katarina

    2012-01-01

    The crystal structures of three conformations, T6, T3R3 and R6, of bovine insulin were solved at 1.40, 1.30 and 1.80 Å resolution, respectively. All conformations crystallized in space group R3. In contrast to the T6 and T3R3 structures, different conformations of the N-terminal B-chain residue Phe......B1 were observed in the R6 insulin structure, resulting in an eightfold doubling of the unit-cell volume upon cooling. The zinc coordination in each conformation was studied by X-ray absorption spectroscopy (XAS), including both EXAFS and XANES. Zinc adopts a tetrahedral coordination in all R3 sites...... molecules, as well as in other high-resolution insulin structures. As the radiation dose for XRD experiments is two orders of magnitude higher compared with that of XAS experiments, the single crystals were exposed to a higher degree of radiation damage that affected the zinc coordination in the T3 sites...

  14. Characterization of local chemistry and disorder in synthetic and natural α-Al2O3 materials by X-ray absorption near edge structure spectroscopy

    International Nuclear Information System (INIS)

    Mottana, A.; Murata, T.

    1997-11-01

    X-ray absorption fine spectra at the Al K-edge were measured experimentally on and calculated theoretically via the multiple-scattering formalism for a chemically pure and physically perfect synthetic α-Al 2 O 3 (α-alumina), a natural 'ruby/sapphire' (corundum) and a series of artificial 'corundum' produced for technical purposes and used as geochemical standards. The Al K-edge spectra differ despite of the identical coordination (short-range arrangement) assumed by O around Al, and vary slightly in relation to the slightly different chemistries of the materials (substitutional defects) as well as on account of the location taken by foreign atoms in the structural lattices (positional defects). A quantitative treatment of the observed changes is made in terms of short-range modification of the coordination polyhedron and of medium- to long-range modifications in the overall structure; both of them induced by substitutions. In some technical 'corundums', the impurities of admixed 'β-alumina', where Al is both in four- and six-fold coordination, produce another small but detectable effect on Al K-edges. Therefore, XAFS spectroscopy proves its potentials for both measuring a light element such as Al, and detecting minor coordination changes and substitutions (ca. 1∼3 wt.% as oxide) of the absorber by dilute other atoms, at least under favorable conditions as those occurring in this system are

  15. Characterization of Functionalized Self-Assembled Monolayers and Surface-Attached Interlocking Molecules Using Near-Edge X-ray Absorption Fine Structure Spectroscopy

    International Nuclear Information System (INIS)

    Willey, T; Willey, T

    2004-01-01

    Quantitative knowledge of the fundamental structure and substrate binding, as well as the direct measurement of conformational changes, are essential to the development of self-assembled monolayers (SAMs) and surface-attached interlocking molecules, catenanes and rotaxanes. These monolayers are vital to development of nano-mechanical, molecular electronic, and biological/chemical sensor applications. This dissertation investigates properties of functionalized SAMs in sulfur-gold based adsorbed molecular monolayers using quantitative spectroscopic techniques including near-edge x-ray absorption fine structure spectroscopy (NEXAFS) and x-ray photoelectron spectroscopy (XPS). The stability of the gold-thiolate interface is addressed. A simple model SAM consisting of dodecanethiol adsorbed on Au(111) degrades significantly in less than 24 hours under ambient laboratory air. S 2p and O 1s XPS show the gold-bound thiolates oxidize to sulfinates and sulfonates. A reduction of organic material on the surface and a decrease in order are observed as the layer degrades. The effect of the carboxyl vs. carboxylate functionalization on SAM structure is investigated. Carboxyl-terminated layers consisting of long alkyl-chain thiols vs. thioctic acid with short, sterically separated, alkyl groups are compared and contrasted. NEXAFS shows a conformational change, or chemical switchability, with carboxyl groups tilted over and carboxylate endgroups more upright. Surface-attached loops and simple surface-attached rotaxanes are quantitatively characterized, and preparation conditions that lead to desired films are outlined. A dithiol is often insufficient to form a molecular species bound at each end to the substrate, while a structurally related disulfide-containing polymer yields surface-attached loops. Similarly, spectroscopic techniques show the successful production of a simple, surface-attached rotaxane that requires a ''molecular riveting'' step to hold the mechanically attached

  16. Ultrafast X-Ray Spectroscopy of Conical Intersections

    Science.gov (United States)

    Neville, Simon P.; Chergui, Majed; Stolow, Albert; Schuurman, Michael S.

    2018-06-01

    Ongoing developments in ultrafast x-ray sources offer powerful new means of probing the complex nonadiabatically coupled structural and electronic dynamics of photoexcited molecules. These non-Born-Oppenheimer effects are governed by general electronic degeneracies termed conical intersections, which play a key role, analogous to that of a transition state, in the electronic-nuclear dynamics of excited molecules. Using high-level ab initio quantum dynamics simulations, we studied time-resolved x-ray absorption (TRXAS) and photoelectron spectroscopy (TRXPS) of the prototypical unsaturated organic chromophore, ethylene, following excitation to its S2(π π*) state. The TRXAS, in particular, is highly sensitive to all aspects of the ensuing dynamics. These x-ray spectroscopies provide a clear signature of the wave packet dynamics near conical intersections, related to charge localization effects driven by the nuclear dynamics. Given the ubiquity of charge localization in excited state dynamics, we believe that ultrafast x-ray spectroscopies offer a unique and powerful route to the direct observation of dynamics around conical intersections.

  17. Ultrafast X-ray absorption study of longitudinal-transverse phonon coupling in electrolyte aqueous solution

    DEFF Research Database (Denmark)

    Jiao, Yishuo; Adams, Bernhard W.; Dohn, Asmus Ougaard

    2017-01-01

    Ultrafast X-ray absorption spectroscopy is applied to study the conversion of longitudinal to transverse phonons in aqueous solution. Permanganate solutes serve as X-ray probe molecules that permit the measurement of the conversion of 13.5 GHz, longitudinal phonons to 27 GHz, transverse phonons...

  18. Ultra-fast X-ray absorption spectroscopy for the study of matter in transient regime; Spectroscopie d'absorption ultra-rapide de rayonnement X pour l'etude de la matiere en regime transitoire

    Energy Technology Data Exchange (ETDEWEB)

    Lecherbourg, L

    2007-12-15

    In this work, we study the physics of dense matter, plasmas or solids, using X-ray absorption spectroscopy. Through the use of sources produced by laser-matter interaction, we have measured the absorption spectra of aluminum and bromine plasmas, as well as those of vanadium dioxide (VO{sub 2}). The measurement of absorption coefficients allows us to probe the dense matter and to study its properties. The experiments are carried out following the same principle: they use the same experimental set-up, called pump-probe. When the matter is dense, the absorption properties of an atom are modified by the surrounding environment. In a plasma, it is mainly the bound- bound transitions which are altered: the shapes of those spectral rays are modified. In a solid, the position of the neighbouring atoms in relation to the absorbing atom modify the structure of absorption levels (bound-free transition). The study of this structure allows us to measure the parameters of the material, and provides information such as the state of the electronic band or the interatomic gaps. The experiments carried out at the LULI have allowed us to probe plasmas in the relatively unknown regime of the Warm Dense Matter. One of the key parameters is that the plasma is characterised independently (FDI diagnostic). It allows for a better comparison of the measured absorption against a calculation made with the numerical model OPA-S. The experiments carried out at INRS have led to the realisation of an experimental system having the characteristics which allow the study of the dynamics of solids showing ultra-fast phase transition. For those experiments, we have used vanadium dioxide as a model system allowing us to test the feasibility of the method. (author)

  19. Charge collection and absorption-limited x-ray sensitivity of pixellated x-ray detectors

    International Nuclear Information System (INIS)

    Kabir, M. Zahangir; Kasap, S.O.

    2004-01-01

    The charge collection and absorption-limited x-ray sensitivity of a direct conversion pixellated x-ray detector operating in the presence of deep trapping of charge carriers is calculated using the Shockley-Ramo theorem and the weighting potential of the individual pixel. The sensitivity of a pixellated x-ray detector is analyzed in terms of normalized parameters; (a) the normalized x-ray absorption depth (absorption depth/photoconductor thickness), (b) normalized pixel width (pixel size/thickness), and (c) normalized carrier schubwegs (schubweg/thickness). The charge collection and absorption-limited sensitivity of pixellated x-ray detectors mainly depends on the transport properties (mobility and lifetime) of the charges that move towards the pixel electrodes and the extent of dependence increases with decreasing normalized pixel width. The x-ray sensitivity of smaller pixels may be higher or lower than that of larger pixels depending on the rate of electron and hole trapping and the bias polarity. The sensitivity of pixellated detectors can be improved by ensuring that the carrier with the higher mobility-lifetime product is drifted towards the pixel electrodes

  20. Chemical shift of U L3 edges in different uranium compounds obtained by X-ray absorption spectroscopy with synchrotron radiation

    International Nuclear Information System (INIS)

    Joseph, D.; Jha, S.N.; Nayak, C.; Bhattacharyya, D.; Babu, P. Venu

    2014-01-01

    Uranium L 3 X-ray absorption edge was measured in various compounds containing uranium in U 4+ , U 5+ and U 5+ oxidation states. The measurements have been carried out at the Energy Dispersive EXAFS beamline (BL-08) at INDUS-2 synchrotron radiation source at RRCAT, Indore. Energy shifts of ∼ 2-3 eV were observed for U L 3 edge in the U-compounds compared to their value in elemental U. The different chemical shifts observed for the compounds having the same oxidation state of the cation but different anions or ligands show the effect of different chemical environments surrounding the cations in determining their X-ray absorption edges in the above compounds. The above chemical effect has been quantitatively described by determining the effective charges on U cation in the above compounds. (author)

  1. Carbon K-edge X-ray absorption spectroscopy and time-dependent density functional theory examination of metal-carbon bonding in metallocene dichlorides.

    Science.gov (United States)

    Minasian, Stefan G; Keith, Jason M; Batista, Enrique R; Boland, Kevin S; Kozimor, Stosh A; Martin, Richard L; Shuh, David K; Tyliszczak, Tolek; Vernon, Louis J

    2013-10-02

    Metal-carbon covalence in (C5H5)2MCl2 (M = Ti, Zr, Hf) has been evaluated using carbon K-edge X-ray absorption spectroscopy (XAS) as well as ground-state and time-dependent hybrid density functional theory (DFT and TDDFT). Differences in orbital mixing were determined experimentally using transmission XAS of thin crystalline material with a scanning transmission X-ray microscope (STXM). Moving down the periodic table (Ti to Hf) has a marked effect on the experimental transition intensities associated with the low-lying antibonding 1a1* and 1b2* orbitals. The peak intensities, which are directly related to the M-(C5H5) orbital mixing coefficients, increase from 0.08(1) and 0.26(3) for (C5H5)2TiCl2 to 0.31(3) and 0.75(8) for (C5H5)2ZrCl2, and finally to 0.54(5) and 0.83(8) for (C5H5)2HfCl2. The experimental trend toward increased peak intensity for transitions associated with 1a1* and 1b2* orbitals agrees with the calculated TDDFT oscillator strengths [0.10 and 0.21, (C5H5)2TiCl2; 0.21 and 0.73, (C5H5)2ZrCl2; 0.35 and 0.69, (C5H5)2HfCl2] and with the amount of C 2p character obtained from the Mulliken populations for the antibonding 1a1* and 1b2* orbitals [8.2 and 23.4%, (C5H5)2TiCl2; 15.3 and 39.7%, (C5H5)2ZrCl2; 20.1 and 50.9%, (C5H5)2HfCl2]. The excellent agreement between experiment, theory, and recent Cl K-edge XAS and DFT measurements shows that C 2p orbital mixing is enhanced for the diffuse Hf (5d) and Zr (4d) atomic orbitals in relation to the more localized Ti (3d) orbitals. These results provide insight into how changes in M-Cl orbital mixing within the metallocene wedge are correlated with periodic trends in covalent bonding between the metal and the cyclopentadienide ancillary ligands.

  2. A new cell for temperature-dependent X-ray absorption spectroscopy of liquid solutions: application to PbBr2 solutions in diethylene glycol.

    Science.gov (United States)

    Lützenkirchen-Hecht, D; Oldag, T; Keil, P; Keller, H L; Frahm, R

    2005-03-01

    An in situ cell has been constructed for temperature-dependent X-ray absorption experiments (EXAFS and XANES) of lead bromine (PbBr2) solutions in diethylene glycol in the temperature range from room temperature up to about 433 K. The solution is kept in a thermostated container made of carbon-reinforced teflon between two thin chemically inert quartz glass windows with a high transmission for hard X-rays. The construction of the cell ensures that these X-ray windows are thermalized so that any possible precipitation of solid products from the solution is inhibited. The cell consists mainly of two hermetically sealed teflon containers for the thermostating fluid (silicon oil) that were fitted together in such a way that a small and variable volume (approximately 2-4 cm3) for the liquid under investigation was achieved. A small thermocouple in a glass enclosure was placed in the solution to maintain temperature control and feedback to the thermostat. The cell design and its performance for temperature-dependent in situ investigations with X-rays are reported. Some preliminary results obtained for PbBr2 solutions in diethylene glycol are given.

  3. Lifetime-broadening-suppressed X-ray absorption spectrum of β-YbAlB4 deduced from Yb 3d → 2p resonant X-ray emission spectroscopy

    International Nuclear Information System (INIS)

    Kawamura, Naomi; Mizumaki, Masaichiro; Kanai, Noriko; Hayashi, Hisashi; Matsuda, Yasuhiro H.; Kuga, Kentaro; Nakatsuji, Satoru; Watanabe, Shinji

    2017-01-01

    In this work, the Yb 3d → 2p (Yb Lα 1,2 ) resonant X-ray emission spectrum of β-YbAlB 4 was acquired using excitation energies around the Yb L 3 -edge, at 2 K. Subsequently, the lifetime-broadening-suppressed (LBS) X-ray absorption structure (XAS) spectrum was obtained using the SIM-RIXS program. This spectrum was found to exhibit clearly resolved pre-edge and shoulder structures. Resonant Lα 1 emission spectra were well reproduced from LBS-XAS profiles over wide ranges of excitation and emission energies. In contrast, noticeable discrepancies appeared between the experimental and simulated Lα 2 emission spectra, suggesting an effect resulting from M 4 M 5 O 1 Coster-Kronig transitions. LBS-XAS, in conjunction with partial fluorescence yield (PFY) XAS and transmission XAS, determined a value for the Yb valence (v) in β-YbAlB 4 of 2.76 ± 0.08 at 2 K. Despite this relatively large uncertainty in v, each method provided a consistent variation in valence (δv) as the temperature was raised from 2 to 280 K: 0.060 ± 0.004 (LBS-XAS), 0.061 ± 0.005 (PFY-XAS) and 0.058 ± 0.007 (transmission XAS). The smaller δv associated with LBS-XAS demonstrates the greater precision of this method. (author)

  4. Observing Solvation Dynamics with Simultaneous Femtosecond X-ray Emission Spectroscopy and X-ray Scattering

    DEFF Research Database (Denmark)

    Haldrup, Kristoffer; Gawelda, Wojciech; Abela, Rafael

    2016-01-01

    and structural changes, and local solvent structural changes are desired. We have studied the intra- and intermolecular dynamics of a model chromophore, aqueous [Fe(bpy)3]2+, with complementary X-ray tools in a single experiment exploiting intense XFEL radiation as a probe. We monitored the ultrafast structural...... rearrangement of the solute with X-ray emission spectroscopy, thus establishing time zero for the ensuing X-ray diffuse scattering analysis. The simultaneously recorded X-ray diffuse scattering atterns reveal slower subpicosecond dynamics triggered by the intramolecular structural dynamics of the photoexcited...

  5. Review of X-ray Tomography and X-ray Fluorescence Spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Shear, Trevor A. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-16

    This literature review will focus on both laboratory and synchrotron based X-ray tomography of materials and highlight the inner workings of these instruments. X-ray fluorescence spectroscopy will also be reviewed and applications of the tandem use of these techniques will be explored. The real world application of these techniques during the internship will also be discussed.

  6. Synchrotron x-ray fluorescence and extended x-ray absorption fine structure analysis

    International Nuclear Information System (INIS)

    Chen, J.R.; Gordon, B.M.; Hanson, A.L.; Jones, K.W.; Kraner, H.W.; Chao, E.C.T.; Minkin, J.A.

    1984-01-01

    The advent of dedicated synchrotron radiation sources has led to a significant increase in activity in many areas of science dealing with the interaction of x-rays with matter. Synchrotron radiation provides intense, linearly polarized, naturally collimated, continuously tunable photon beams, which are used to determine not only the elemental composition of a complex, polyatomic, dilute material but also the chemical form of the elements with improved accuracy. Examples of the application of synchrotron radiation include experiments in synchrotron x-ray fluorescence (SXRF) analysis and extended x-ray absorption fine structure (EXAFS) analysis. New synchrotron radiation x-ray microprobes for elemental analysis in the parts per billion range are under construction at several laboratories. 76 references, 24 figures

  7. Ab Initio Molecular Dynamics of Uranium Incorporated in Goethite (α-FeOOH): Interpretation of X-ray Absorption Spectroscopy of Trace Polyvalent Metals.

    Science.gov (United States)

    Kerisit, Sebastien; Bylaska, Eric J; Massey, Michael S; McBriarty, Martin E; Ilton, Eugene S

    2016-11-21

    Incorporation of economically or environmentally consequential polyvalent metals into iron (oxyhydr)oxides has applications in environmental chemistry, remediation, and materials science. A primary tool for characterizing the local coordination environment of such metals, and therefore building models to predict their behavior, is extended X-ray absorption fine structure spectroscopy (EXAFS). Accurate structural information can be lacking yet is required to constrain and inform data interpretation. In this regard, ab initio molecular dynamics (AIMD) was used to calculate the local coordination environment of minor amounts of U incorporated in the structure of goethite (α-FeOOH). U oxidation states (VI, V, and IV) and charge compensation schemes were varied. Simulated trajectories were used to calculate the U L III -edge EXAFS function and fit experimental EXAFS data for U incorporated into goethite under reducing conditions. Calculations that closely matched the U EXAFS of the well-characterized mineral uraninite (UO 2 ), and constrained the S 0 2 parameter to be 0.909, validated the approach. The results for the U-goethite system indicated that U(V) substituted for structural Fe(III) in octahedral uranate coordination. Charge balance was achieved by the loss of one structural proton coupled to addition of one electron into the solid (-1 H + , +1 e - ). The ability of AIMD to model higher energy states thermally accessible at room temperature is particularly relevant for protonated systems such as goethite, where proton transfers between adjacent octahedra had a dramatic effect on the calculated EXAFS. Vibrational effects as a function of temperature were also estimated using AIMD, allowing separate quantification of thermal and configurational disorder. In summary, coupling AIMD structural modeling and EXAFS experiments enables modeling of the redox behavior of polyvalent metals that are incorporated in conductive materials such as iron (oxyhydr)oxides, with

  8. Tetrahalide complexes of the [U(NR)2]2+ ion: synthesis, theory, and chlorine K-edge X-ray absorption spectroscopy.

    Science.gov (United States)

    Spencer, Liam P; Yang, Ping; Minasian, Stefan G; Jilek, Robert E; Batista, Enrique R; Boland, Kevin S; Boncella, James M; Conradson, Steven D; Clark, David L; Hayton, Trevor W; Kozimor, Stosh A; Martin, Richard L; MacInnes, Molly M; Olson, Angela C; Scott, Brian L; Shuh, David K; Wilkerson, Marianne P

    2013-02-13

    Synthetic routes to salts containing uranium bis-imido tetrahalide anions [U(NR)(2)X(4)](2-) (X = Cl(-), Br(-)) and non-coordinating NEt(4)(+) and PPh(4)(+) countercations are reported. In general, these compounds can be prepared from U(NR)(2)I(2)(THF)(x) (x = 2 and R = (t)Bu, Ph; x = 3 and R = Me) upon addition of excess halide. In addition to providing stable coordination complexes with Cl(-), the [U(NMe)(2)](2+) cation also reacts with Br(-) to form stable [NEt(4)](2)[U(NMe)(2)Br(4)] complexes. These materials were used as a platform to compare electronic structure and bonding in [U(NR)(2)](2+) with [UO(2)](2+). Specifically, Cl K-edge X-ray absorption spectroscopy (XAS) and both ground-state and time-dependent hybrid density functional theory (DFT and TDDFT) were used to probe U-Cl bonding interactions in [PPh(4)](2)[U(N(t)Bu)(2)Cl(4)] and [PPh(4)](2)[UO(2)Cl(4)]. The DFT and XAS results show the total amount of Cl 3p character mixed with the U 5f orbitals was roughly 7-10% per U-Cl bond for both compounds, which shows that moving from oxo to imido has little effect on orbital mixing between the U 5f and equatorial Cl 3p orbitals. The results are presented in the context of recent Cl K-edge XAS and DFT studies on other hexavalent uranium chloride systems with fewer oxo or imido ligands.

  9. Covalency in lanthanides. An X-ray absorption spectroscopy and density functional theory study of LnCl6(x-) (x = 3, 2).

    Science.gov (United States)

    Löble, Matthias W; Keith, Jason M; Altman, Alison B; Stieber, S Chantal E; Batista, Enrique R; Boland, Kevin S; Conradson, Steven D; Clark, David L; Lezama Pacheco, Juan; Kozimor, Stosh A; Martin, Richard L; Minasian, Stefan G; Olson, Angela C; Scott, Brian L; Shuh, David K; Tyliszczak, Tolek; Wilkerson, Marianne P; Zehnder, Ralph A

    2015-02-25

    Covalency in Ln-Cl bonds of Oh-LnCl6(x-) (x = 3 for Ln = Ce(III), Nd(III), Sm(III), Eu(III), Gd(III); x = 2 for Ln = Ce(IV)) anions has been investigated, primarily using Cl K-edge X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TDDFT); however, Ce L3,2-edge and M5,4-edge XAS were also used to characterize CeCl6(x-) (x = 2, 3). The M5,4-edge XAS spectra were modeled using configuration interaction calculations. The results were evaluated as a function of (1) the lanthanide (Ln) metal identity, which was varied across the series from Ce to Gd, and (2) the Ln oxidation state (when practical, i.e., formally Ce(III) and Ce(IV)). Pronounced mixing between the Cl 3p- and Ln 5d-orbitals (t2g* and eg*) was observed. Experimental results indicated that Ln 5d-orbital mixing decreased when moving across the lanthanide series. In contrast, oxidizing Ce(III) to Ce(IV) had little effect on Cl 3p and Ce 5d-orbital mixing. For LnCl6(3-) (formally Ln(III)), the 4f-orbitals participated only marginally in covalent bonding, which was consistent with historical descriptions. Surprisingly, there was a marked increase in Cl 3p- and Ce(IV) 4f-orbital mixing (t1u* + t2u*) in CeCl6(2-). This unexpected 4f- and 5d-orbital participation in covalent bonding is presented in the context of recent studies on both tetravalent transition metal and actinide hexahalides, MCl6(2-) (M = Ti, Zr, Hf, U).

  10. Electronic structures of B 2p and C 2p levels in boron-doped diamond films studied using soft x-ray absorption and emission spectroscopy

    Science.gov (United States)

    Nakamura, Jin; Kabasawa, Eiki; Yamada, Nobuyoshi; Einaga, Yasuaki; Saito, Daisuke; Isshiki, Hideo; Yugo, Shigemi; Perera, Rupert C. C.

    2004-12-01

    X-ray absorption (XAS) and emission (XES) spectroscopy near B K and C K edges have been performed on metallic ( ˜0.1at.% B, B-diamond) and semiconducting ( ˜0.03at.% B and N, BN-diamond) doped diamond films. Both B K XAS and XES spectra show a metallic partial density of states (PDOS) with the Fermi energy of 185.3eV , and there is no apparent boron-concentration dependence in contrast to the different electric property. In C K XAS spectrum of B-diamond, the impurity state ascribed to boron is clearly observed near the Fermi level. The Fermi energy is found to be almost same with the top of the valence band of nondoped diamond: EV=283.9eV . C K XAS of BN-diamond shows both the B-induced shallow level and N-induced deep and broad levels as the in-gap states, in which the shallow level is in good agreement with the activation energy (Ea=0.37eV) estimated from the temperature dependence of the conductivity; namely, the change in C2p PDOS of impurity-induced metallization is directly observed. The electric property of this diamond is ascribed mainly to the electronic structure of C2p near the Fermi level. The observed XES spectra are compared with the discrete variational Xα ( DVXα ) cluster calculation. The DVXα result supports the strong hybridization between B2p and C2p observed in XAS and XES spectra, and suggests that the small amount of boron (⩽0.1at.%) in diamond occupies the substitutional site rather than interstitial site.

  11. X-ray spectroscopy from exotic atoms

    International Nuclear Information System (INIS)

    Hartmann, F.J.

    1994-01-01

    Why do experimentalists study exotic atoms, in particular antiprotonic atoms? The answer is simple: the information about electromagnetic, weak, and strong interactions that can be obtained by doing X-ray spectroscopy from exotic atoms is really worth the effort. It is possible to (1) enlarge the knowledge about the properties of exotic particles (such as mass and magnetic moment); (2) open a possibility to test quantum electrodynamics; (3) get detailed insight into the shape of nuclei (characterized by the nuclear radium and higher momenta) and even into the neutron distribution in the nucleus (neutron halo); and (4) use it as a powerful tool to learn about the strong interaction at very low relative hadron-nucleon velocities

  12. Detection of nanocrystallinity by X-ray absorption spectroscopy in thin film transition metal/rare-earth atom, elemental and complex oxides

    International Nuclear Information System (INIS)

    Edge, L.F.; Schlom, D.G.; Stemmer, S.; Lucovsky, G.; Luning, J.

    2006-01-01

    Nanocrystallinity has been detected in the X-ray absorption spectra of transition metal and rare-earth oxides by (i) removal of d-state degeneracies in the (a) Ti and Sc L 3 spectra of TiO 2 and LaScO 3 , respectively, and (b) O K 1 spectra of Zr(Hf)O 2 , Y 2 O 3 , LaScO 3 and LaAlO 3 , and by the (ii) detection of the O-atom vacancy in the O K 1 edge ZrO 2 -Y 2 O 3 alloys. Spectroscopic detection is more sensitive than X-ray diffraction with a limit of ∼2 nm as compared to >5 mm. Other example includes detection of ZrO 2 nanocrystallinity in phase-separated Zr(Hf) silicate alloys

  13. Thomson Thick X-Ray Absorption in a Broad Absorption Line Quasar, PG 0946+301.

    Science.gov (United States)

    Mathur; Green; Arav; Brotherton; Crenshaw; deKool; Elvis; Goodrich; Hamann; Hines; Kashyap; Korista; Peterson; Shields; Shlosman; van Breugel W; Voit

    2000-04-20

    We present a deep ASCA observation of a broad absorption line quasar (BALQSO) PG 0946+301. The source was clearly detected in one of the gas imaging spectrometers, but not in any other detector. If BALQSOs have intrinsic X-ray spectra similar to normal radio-quiet quasars, our observations imply that there is Thomson thick X-ray absorption (NH greater, similar1024 cm-2) toward PG 0946+301. This is the largest column density estimated so far toward a BALQSO. The absorber must be at least partially ionized and may be responsible for attenuation in the optical and UV. If the Thomson optical depth toward BALQSOs is close to 1, as inferred here, then spectroscopy in hard X-rays with large telescopes like XMM would be feasible.

  14. Application of X-ray spectroscopy in nondestructive photon activation analysis

    International Nuclear Information System (INIS)

    Weise, H.-P.; Segebade, Chr.

    1977-01-01

    The use of X-ray spectroscopy for the qualitative and quantitative analysis of samples activated by 30 MeV bremsstrahlung from an electron linear accelerator. Detection limits are calculated from the measured X-ray spectra and compared with those for γ-ray spectroscopy. In general, the detection limits for γ-ray and X-ray spectroscopy are comparable. Higher sensitivities for X-ray spectroscopy are observed when only low intensity γ-rays are emitted by the activation products. X-ray spectroscopy should be applied in three cases: (a) low γ-ray emission probability, (b) extremely complicated γ-ray spectrum, (c) overlapping of γ-ray lines from different elements. γ-ray spectroscopy should be preferred for the analysis of light elements for two reasons: very strong absorption of low energy X-rays (low Z) within the sample, low X-ray emission probability for the activation products of light elements. Therefore no attempt was made to use X-ray spectroscopy for the analysis of elements below Ti. Some practical applications of X-ray spectroscopy in nondestructive multielement analysis are quoted. (T.G.)

  15. Cone-beam x-ray luminescence computed tomography based on x-ray absorption dosage

    Science.gov (United States)

    Liu, Tianshuai; Rong, Junyan; Gao, Peng; Zhang, Wenli; Liu, Wenlei; Zhang, Yuanke; Lu, Hongbing

    2018-02-01

    With the advances of x-ray excitable nanophosphors, x-ray luminescence computed tomography (XLCT) has become a promising hybrid imaging modality. In particular, a cone-beam XLCT (CB-XLCT) system has demonstrated its potential in in vivo imaging with the advantage of fast imaging speed over other XLCT systems. Currently, the imaging models of most XLCT systems assume that nanophosphors emit light based on the intensity distribution of x-ray within the object, not completely reflecting the nature of the x-ray excitation process. To improve the imaging quality of CB-XLCT, an imaging model that adopts an excitation model of nanophosphors based on x-ray absorption dosage is proposed in this study. To solve the ill-posed inverse problem, a reconstruction algorithm that combines the adaptive Tikhonov regularization method with the imaging model is implemented for CB-XLCT reconstruction. Numerical simulations and phantom experiments indicate that compared with the traditional forward model based on x-ray intensity, the proposed dose-based model could improve the image quality of CB-XLCT significantly in terms of target shape, localization accuracy, and image contrast. In addition, the proposed model behaves better in distinguishing closer targets, demonstrating its advantage in improving spatial resolution.

  16. Architecture of Pd-Au bimetallic nanoparticles in sodium bis(2-ethylhexyl)sulfosuccinate reverse micelles as investigated by X-ray absorption spectroscopy.

    Science.gov (United States)

    Chen, Ching-Hsiang; Sarma, Loka Subramanyam; Chen, Jium-Ming; Shih, Shou-Chu; Wang, Guo-Rung; Liu, Din-Goa; Tang, Mau-Tsu; Lee, Jyh-Fu; Hwang, Bing-Joe

    2007-09-01

    In this study, we demonstrate the unique application of X-ray absorption spectroscopy (XAS) as a fundamental characterization tool to help in designing and controlling the architecture of Pd-Au bimetallic nanoparticles within a water-in-oil microemulsion system of water/sodium bis(2-ethylhexyl)sulfosuccinate (AOT)/n-heptane. Structural insights obtained from the in situ XAS measurements recorded at each step during the formation process revealed that Pd-Au bimetallic clusters with various Pd-Au atomic stackings are formed by properly performing hydrazine reduction and redox transmetalation reactions sequentially within water-in-oil microemulsions. A structural model is provided to explain reasonably each reaction step and to give detailed insight into the nucleation and growth mechanism of Pd-Au bimetallic clusters. The combination of in situ XAS analysis at both the Pd K-edge and the Au L(III)-edge and UV-vis absorption spectral features confirms that the formation of Pd-Au bimetallic clusters follows a (Pd(nuclei)-Au(stack))-Pd(surf) stacking. This result further implies that the thickness of Au(stack) and Pd(surf) layers may be modulated by varying the dosage of the Au precursor and hydrazine, respectively. In addition, a bimetallic (Pd-Au)(alloy) nanocluster with a (Pd(nuclei)-Au(stack))-(Pd-Au(alloy))(surf) stacking was also designed and synthesized in order to check the feasibility of Pd(surf) layer modification. The result reveals that the Pd(surf) layer of the stacked (Pd(nuclei)-Au)(stack) bimetallic clusters can be successfully modified to form a (Au-Pd alloy)(surf) layer by a co-reduction of Pd and Au ions by hydrazine. Further, we demonstrate the alloying extent or atomic distribution of Pd and Au in Pd-Au bimetallic nanoparticles from the derived XAS structural parameters. The complete XAS-based methodology, demonstrated here on the Pd-Au bimetallic system, can easily be extended to design and control the alloying extent or atomic distribution, atomic

  17. Investigation of the electronic structure of high-temperature superconductors and related transition metal oxides with near-edge x-ray absorption spectroscopy

    International Nuclear Information System (INIS)

    Gerhold, S.

    2001-01-01

    The unoccupied electronic structure and its orbital character has been studied with polarization-dependent near-edge x-ray absorption spectroscopy (NEXAFS) for selected high-temperature superconductors (HTSC) and related transition metal oxides. Although YBa 2 Cu 3 O 7-δ (Y-123) is arguably the best-investigated HTSC a conclusive NEXAFS study on how partial substitution of Cu by other transition metals affects the electronic structure has sorely been missing. The study presented here on a series of well characterized YBa 2 Cu 3-x Fe x O y single crystals shows that the cause for T c suppression is not at all magnetic pair breaking but charge carrier depletion, primarily in the chains; effects from disorder cannot be excluded. Annealing at high oxygen pressure increases along with oxygen content both the hole concentration and T c . Fe 3d-O 2p-derived states contribute prominently to the spectra for all polarizations a few eV above E F . Iron prefers a trivalent state in Y-123; upon reduction a spin transition can be observed. As YBa 2 Cu 3-x Fe x O y single crystals cannot be detwinned it is very difficult to distinguish between contributions from planes and chains to the spectra. In this situation thin films grown with a reduced degree of twinning ('twin-poor') allow more detailed investigations. An extended self-absorption correction was developed for fluorescence yield NEXAFS on epitactical HTSC thin films. Its application to twin-poor Y-123 thin films demonstrates that (apart from the effect of residual twins) the spectral information is equivalent to that of detwinned single crystals for a range of optimum film thicknesses, and this in turn allows to augment the NEXAFS study of YBa 2 Cu 3-x Fe x O y with spectra for corresponding twin-poor thin films. The system Ca 2-x (Sr,La) x RuO 4 is structurally related to the HTSCs; the development of its unoccupied electronic structure with x was investigated in this work, with emphasis on the metal

  18. X-ray spectroscopy and X-ray crystallography of metalloenzymes at XFELs

    International Nuclear Information System (INIS)

    Yano, Junko

    2016-01-01

    The ultra-bright femtosecond X-ray pulses provided by X-ray Free Electron Lasers (XFELs) open capabilities for studying the structure and dynamics of a wide variety of biological and inorganic systems beyond what is possible at synchrotron sources. Although the structure and chemistry at the catalytic sites have been studied intensively in both biological and inorganic systems, a full understanding of the atomic-scale chemistry requires new approaches beyond the steady state X-ray crystallography and X-ray spectroscopy at cryogenic temperatures. Following the dynamic changes in the geometric and electronic structure at ambient conditions, while overcoming X-ray damage to the redox active catalytic center, is key for deriving reaction mechanisms. Such studies become possible by using the intense and ultra-short femtosecond X-ray pulses from an XFEL, where sample is probed before it is damaged. We have developed methodology for simultaneously collecting crystallography data and X-ray emission spectra, using an energy dispersive spectrometer at ambient conditions. In addition, we have developed a way to collect metal L-edge data of dilute samples using soft X-rays at XFELs. The advantages and challenges of these methods will be described in this review. (author)

  19. X-ray Absorption Spectroscopy Combined with Time-Dependent Density Functional Theory Elucidates Differential Substitution Pathways of Au(I) and Au(III) with Zinc Fingers.

    Science.gov (United States)

    Abbehausen, Camilla; de Paiva, Raphael Enoque Ferraz; Bjornsson, Ragnar; Gomes, Saulo Quintana; Du, Zhifeng; Corbi, Pedro Paulo; Lima, Frederico Alves; Farrell, Nicholas

    2018-01-02

    A combination of two elements' (Au, Zn) X-ray absorption spectroscopy (XAS) and time-dependent density functional theory (TD-DFT) allowed the elucidation of differential substitution pathways of Au(I) and Au(III) compounds reacting with biologically relevant zinc fingers (ZnFs). Gold L 3 -edge XAS probed the interaction of gold and the C-terminal Cys 2 HisCys finger of the HIV-1 nucleocapsid protein NCp7, and the Cys 2 His 2 human transcription factor Sp1. The use of model compounds helped assign oxidation states and the identity of the gold-bound ligands. The computational studies accurately reproduced the experimental XAS spectra and allowed the proposition of structural models for the interaction products at early time points. The direct electrophilic attack on the ZnF by the highly thiophilic Au(I) resulted in a linear P-Au-Cys coordination sphere after zinc ejection whereas for the Sp1, loss of PEt 3 results in linear Cys-Au-Cys or Cys-Au-His arrangements. Reactions with Au(III) compounds, on the other hand, showed multiple binding modes. Prompt reaction between [AuCl(dien)] 2+ and [Au(dien)(DMAP)] 3+ with Sp1 showed a partially reduced Au center and a final linear His-Au-His coordination. Differently, in the presence of NCp7, [AuCl(dien)] 2+ readily reduces to Au(I) and changes from square-planar to linear geometry with Cys-Au-His coordination, while [Au(dien)(DMAP)] 3+ initially maintains its Au(III) oxidation state and square-planar geometry and the same first coordination sphere. The latter is the first observation of a "noncovalent" interaction of a Au(III) complex with a zinc finger and confirms early hypotheses that stabilization of Au(III) occurs with N-donor ligands. Modification of the zinc coordination sphere, suggesting full or partial zinc ejection, is observed in all cases, and for [Au(dien)(DMAP)] 3+ this represents a novel mechanism for nucleocapsid inactivation. The combination of XAS and TD-DFT presents the first direct experimental

  20. From single-site tantalum complexes to nanoparticles of TaxNy and TaOxNy supported on silica: elucidation of synthesis chemistry by dynamic nuclear polarization surface enhanced NMR spectroscopy and X-ray absorption spectroscopy

    KAUST Repository

    Mohandas, Janet Chakkamadathil

    2017-06-08

    Air-stable catalysts consisting of tantalum nitride nanoparticles represented as a mixture of TaxNy and TaOxNy with diameters in the range of 0.5 to 3 nm supported on highly dehydroxylated silica were synthesized from TaMe5 (Me = methyl) and dimeric Ta-2(OMe)(10) with guidance by the principles of surface organometallic chemistry (SOMC). Characterization of the supported precursors and the supported nanoparticles formed from them was carried out by IR, NMR, UV-Vis, extended X-ray absorption fine structure, and X-ray photoelectron spectroscopies complemented with XRD and high-resolution TEM, with dynamic nuclear polarization surface enhanced NMR spectroscopy being especially helpful by providing enhanced intensities of the signals of H-1, C-13, Si-29, and N-15 at their natural abundances. The characterization data provide details of the synthesis chemistry, including evidence of (a) O-2 insertion into Ta-CH3 species on the support and (b) a binuclear to mononuclear transformation of species formed from Ta-2(OMe)(10) on the support. A catalytic test reaction, cyclooctene epoxidation, was used to probe the supported nanoparticles, with 30% H2O2 serving as the oxidant. The catalysts gave selectivities up to 98% for the epoxide at conversions as high as 99% with a 3.4 wt% loading of Ta present as TaxNy/TaOxNy.

  1. Unoccupied density of states of La2–xSrxNiO4+δ studied by polarization-dependent x-ray-absorption spectroscopy and bremsstrahlung isochromat spectroscopy

    NARCIS (Netherlands)

    Kuiper, P.; Elp, J. van; Sawatzky, G.A.; Fujimori, A.; Hosoya, S.; Leeuw, D.M. de

    1991-01-01

    Oxygen 1s x-ray-absorption measurements of La2–xSrxNiO4+δ (0≤x≤1.15) are presented, together with O 1s polarization-dependent x-ray absorption on single-crystal La1.85Sr0.15NiO4. It is concluded that the charge-compensating holes have mainly oxygen 2p character. The Ni 3d9 final states reached

  2. X-ray absorption intensity at high-energy region

    International Nuclear Information System (INIS)

    Fujikawa, Takashi; Kaneko, Katsumi

    2012-01-01

    We theoretically discuss X-ray absorption intensity in high-energy region far from the deepest core threshold to explain the morphology-dependent mass attenuation coefficient of some carbon systems, carbon nanotubes (CNTs), highly oriented pyrolytic graphite (HOPG) and fullerenes (C 60 ). The present theoretical approach is based on the many-body X-ray absorption theory including the intrinsic losses (shake-up losses). In the high-energy region the absorption coefficient has correction term dependent on the solid state effects given in terms of the polarization part of the screened Coulomb interaction W p . We also discuss the tail of the valence band X-ray absorption intensity. In the carbon systems C 2s contribution has some influence on the attenuation coefficient even in the high energy region at 20 keV.

  3. Recent applications of hard x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Weiland, Conan; Woicik, Joseph C., E-mail: Joseph.Woicik@NIST.gov [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Rumaiz, Abdul K. [National Synchrotron Light Source II, Brookhaven National Laboratory, Upton, New York 11973 (United States); Pianetta, Piero [SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2016-05-15

    Recent applications of hard x-ray photoelectron spectroscopy (HAXPES) demonstrate its many capabilities in addition to several of its limitations. Examples are given, including measurement of buried interfaces and materials under in situ or in operando conditions, as well as measurements under x-ray standing-wave and resonant excitation. Physical considerations that differentiate HAXPES from photoemission measurements utilizing soft x-ray and ultraviolet photon sources are also presented.

  4. Structural determination of individual chemical species in a mixed system by iterative transformation factor analysis-based X-ray absorption spectroscopy combined with UV-visible absorption and quantum chemical calculation.

    Science.gov (United States)

    Ikeda, Atsushi; Hennig, Christoph; Rossberg, André; Tsushima, Satoru; Scheinost, Andreas C; Bernhard, Gert

    2008-02-15

    A multitechnique approach using extended X-ray absorption fine structure (EXAFS) spectroscopy based on iterative transformation factor analysis (ITFA), UV-visible absorption spectroscopy, and density functional theory (DFT) calculations has been performed in order to investigate the speciation of uranium(VI) nitrate species in acetonitrile and to identify the complex structure of individual species in the system. UV-visible spectral titration suggests that there are four different species in the system, that is, pure solvated species, mono-, di-, and trinitrate species. The pure EXAFS spectra of these individual species are extracted by ITFA from the measured spectral mixtures on the basis of the speciation distribution profile calculated from the UV-visible data. Data analysis of the extracted EXAFS spectra, with the help of DFT calculations, reveals the most probable complex structures of the individual species. The pure solvated species corresponds to a uranyl hydrate complex with an equatorial coordination number (CNeq) of 5, [UO2(H2O)5]2+. Nitrate ions tend to coordinate to the uranyl(VI) ion in a bidentate fashion rather than a unidentate one in acetonitrile for all the nitrate species. The mononitrate species forms the complex of [UO2(H2O)3NO3]+ with a CNeq value of 5, while the di- and trinitrate species have a CNeq value of 6, corresponding to [UO2(H2O)2(NO3)2]0 (D2h) and [UO2(NO3)3]- (D3h), respectively.

  5. Electronic structure of Cr doped Fe3O4 thin films by X-ray absorption near-edge structure spectroscopy

    Science.gov (United States)

    Chen, Chi-Liang; Dong, Chung-Li; Asokan, Kandasami; Chern, G.; Chang, C. L.

    2018-04-01

    Present study reports the electronic structures of Cr doped Fe3O4 (Fe3-xCrxO4 (0 ≤ x ≤ 3) grown on MgO (100) substrates in the form of thin films fabricated by a plasma-oxygen assisted Molecular Beam Epitaxy (MBE). X-ray absorption near-edge structure (XANES) spectra at Cr & Fe L-, and O K-edges were used to understand the electronic structure: changes in the bonding nature, valence states, and site occupancies. Cr doping in Fe3O4 results in the change of charge transfer, crystal structure, and selective occupation of ions in octahedral and tetrahedral sites. Such change modifies the electrical and magnetic properties due to the covalency of Cr ions. The physical and chemical properties of ferrites are strongly dependent on the lattice site, ion size of dopant, and magnetic nature present at different structural symmetry of the spinel structure.

  6. Identification of isomers in the gas phase and as adsorbates by near-edge X-ray absorption fine structure spectroscopy: Cis- and trans-stilbene

    International Nuclear Information System (INIS)

    Püttner, Ralph; Schmidt-Weber, Philipp; Kampen, Thorsten; Kolczewski, Christine; Hermann, Klaus; Horn, Karsten

    2017-01-01

    Highlights: • NEXAFS spectra of the cis- and trans-isomer of stilbene reveal distinct differences by which the isomers can be distinguished. • DFT calculations using the transition potential approach assign specific transitions that are different in the two isomers. • On Si(100), these differences in NEXAFS are also observed, suggesting that their conformations survive in the bonding situation. • NEXAFS is thus shown to be a sensitive tool to distinguish isomers in adsorbed species. - Abstract: Near-edge x-ray absorption fine structure spectra of the cis- and trans-isomers of stilbene in the gas phase reveal clear differences, which are analyzed by results from density-functional theory calculations using the transition potential approach. The differences between the two species also occur in stilbene adsorbed on Si(100), opening the way towards studying structural changes in molecules in different surface environments, and configurational switching in organic molecules on surfaces in particular.

  7. Depth distribution of secondary phases in kesterite Cu2ZnSnS4 by angle-resolved X-ray absorption spectroscopy

    Directory of Open Access Journals (Sweden)

    J. Just

    2017-12-01

    Full Text Available The depth distribution of secondary phases in the solar cell absorber material Cu2ZnSnS4 (CZTS is quantitatively investigated using X-ray Absorption Near Edge Structure (XANES analysis at the K-edge of sulfur at varying incidence angles. Varying information depths from several nanometers up to the full thickness is achieved. A quantitative profile of the phase distribution is obtained by a self-consistent fit of a multilayer model to the XANES spectra for different angles. Single step co-evaporated CZTS thin-films are found to exhibit zinc and copper sulfide secondary phases preferentially at the front or back interfaces of the film.

  8. Identification of isomers in the gas phase and as adsorbates by near-edge X-ray absorption fine structure spectroscopy: Cis- and trans-stilbene

    Energy Technology Data Exchange (ETDEWEB)

    Püttner, Ralph [Department of Physics, Freie Universität Berlin, 14195 Berlin (Germany); Schmidt-Weber, Philipp [Fritz Haber Institute of the Max Planck Society, 14195 Berlin (Germany); Kampen, Thorsten [SPECS Surface Nano Analysis GmbH, 13355 Berlin (Germany); Kolczewski, Christine [Deutsches Museum München, 80538 Munich (Germany); Hermann, Klaus [Fritz Haber Institute of the Max Planck Society, 14195 Berlin (Germany); Horn, Karsten, E-mail: horn@fhi-berlin.mpg.de [Fritz Haber Institute of the Max Planck Society, 14195 Berlin (Germany)

    2017-02-15

    Highlights: • NEXAFS spectra of the cis- and trans-isomer of stilbene reveal distinct differences by which the isomers can be distinguished. • DFT calculations using the transition potential approach assign specific transitions that are different in the two isomers. • On Si(100), these differences in NEXAFS are also observed, suggesting that their conformations survive in the bonding situation. • NEXAFS is thus shown to be a sensitive tool to distinguish isomers in adsorbed species. - Abstract: Near-edge x-ray absorption fine structure spectra of the cis- and trans-isomers of stilbene in the gas phase reveal clear differences, which are analyzed by results from density-functional theory calculations using the transition potential approach. The differences between the two species also occur in stilbene adsorbed on Si(100), opening the way towards studying structural changes in molecules in different surface environments, and configurational switching in organic molecules on surfaces in particular.

  9. Theory of inelastic scattering and absorption of X-rays

    CERN Document Server

    Veenendaal, Michel van

    2015-01-01

    This comprehensive, self-contained guide to X-ray spectroscopy will equip you with everything you need to begin extracting the maximum amount of information available from X-ray spectra. Key topics such as the interaction between X-rays and matter, the basic theory of spectroscopy, and selection and sum rules, are introduced from the ground up, providing a solid theoretical grounding. The book also introduces core underlying concepts such as atomic structure, solid-state effects, the fundamentals of tensor algebra and group theory, many-body interactions, scattering theory, and response functions, placing spectroscopy within a broader conceptual framework, and encouraging a deep understanding of this essential theoretical background. Suitable for graduate students, researchers, materials scientists and optical engineers, this is the definitive guide to the theory behind this powerful and widely used technique.

  10. ON NEUTRAL ABSORPTION AND SPECTRAL EVOLUTION IN X-RAY BINARIES

    International Nuclear Information System (INIS)

    Miller, J. M.; Cackett, E. M.; Reis, R. C.

    2009-01-01

    Current X-ray observatories make it possible to follow the evolution of transient and variable X-ray binaries across a broad range in luminosity and source behavior. In such studies, it can be unclear whether evolution in the low-energy portion of the spectrum should be attributed to evolution in the source, or instead to evolution in neutral photoelectric absorption. Dispersive spectrometers make it possible to address this problem. We have analyzed a small but diverse set of X-ray binaries observed with the Chandra High Energy Transmission Grating Spectrometer across a range in luminosity and different spectral states. The column density in individual photoelectric absorption edges remains constant with luminosity, both within and across source spectral states. This finding suggests that absorption in the interstellar medium strongly dominates the neutral column density observed in spectra of X-ray binaries. Consequently, evolution in the low-energy spectrum of X-ray binaries should properly be attributed to evolution in the source spectrum. We discuss our results in the context of X-ray binary spectroscopy with current and future X-ray missions.

  11. Uranium concentrate analysis by X-ray fluorescence spectroscopy

    International Nuclear Information System (INIS)

    Diaz-Guerra, J.P.; Bayon, A.; Roca, R.

    1978-01-01

    The determination of As, Ca, Fe, Mo, P, S, Si. Th, V and U in uranium concentrates by X-ray fluorescence spectroscopy has been studied. As and U are determined in nitric solutions and for the rest of elements analysis is performed by a bead fusion technique using Li 2 B 4 O 7 and Li 2 CO 3 as fluxes. Although the uranium matrix minimizes the absorption and enhancement effects, because of the content variations of this element it is advisable to operate at a constant level of U 3 O 8 . Despite the high matrix absorption and the large dilution of the samples, sensitivity and speed are found to be satisfactory as the result of the use of a high sensitivity automatic spectrometer. The spectral interferences of Mo on S and P, and of Pb on As have been particularly considered. (author) [es

  12. Astrophysical extended X-ray absorption fine-structure analysis

    International Nuclear Information System (INIS)

    Woo, J.W.; Forrey, R.C.; Cho, K.; Department of Physics and Division of Applied Sciences, Harvard University)

    1997-01-01

    We present an astrophysical extended X-ray absorption fine-structure (EXAFS) analysis (AEA) tool. The AEA tool is designed to generate a numerical model of the modification to the X-ray absorption coefficient due to the EXAFS phenomenon. We have constructed a complete database (elements up to the atomic number 92) of EXAFS parameters: central atom phase shift (2δ 1 ), backscattering phase shift (φ b ), and backscattering amplitude (F). Using the EXAFS parameter data base, the AEA tool can generate a numerical model of any compound when the atomic numbers of neighboring atoms and their distances to the central X-ray-absorbing atom are given. copyright 1997 The American Astronomical Society

  13. Ultrafast absorption of intense x rays by nitrogen molecules

    Energy Technology Data Exchange (ETDEWEB)

    Buth, Christian [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liu Jicai [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Department of Mathematics and Physics, North China Electric Power University, 102206 Beijing (China); Chen, Mau Hsiung [Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Cryan, James P. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Fang Li; Hoener, Matthias; Berrah, Nora [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Glownia, James M. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Coffee, Ryan N. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

    2012-06-07

    We devise a theoretical description for the response of nitrogen molecules (N{sub 2}) to ultrashort and intense x rays from the free electron laser Linac Coherent Light Source (LCLS). We set out from a rate-equation description for the x-ray absorption by a nitrogen atom. The equations are formulated using all one-x-ray-photon absorption cross sections and the Auger and radiative decay widths of multiply-ionized nitrogen atoms. Cross sections are obtained with a one-electron theory and decay widths are determined from ab initio computations using the Dirac-Hartree-Slater (DHS) method. We also calculate all binding and transition energies of nitrogen atoms in all charge states with the DHS method as the difference of two self-consistent field (SCF) calculations ({Delta}SCF method). To describe the interaction with N{sub 2}, a detailed investigation of intense x-ray-induced ionization and molecular fragmentation are carried out. As a figure of merit, we calculate ion yields and the average charge state measured in recent experiments at the LCLS. We use a series of phenomenological models of increasing sophistication to unravel the mechanisms of the interaction of x rays with N{sub 2}: a single atom, a symmetric-sharing model, and a fragmentation-matrix model are developed. The role of the formation and decay of single and double core holes, the metastable states of N{sub 2}{sup 2+}, and molecular fragmentation are explained.

  14. An X-ray absorption spectroelectrochemical cell for radioactive solutions

    International Nuclear Information System (INIS)

    Rettig, D.; Herrmann, S.; Mitschke, F.; Vonau, W.; Brendler, V.; Geipel, G.; Reich, T.; Bernhard, G.

    2002-01-01

    A spectroelectrochemical cell was designed and constructed for measurement of X-ray absorption spectra under electrochemical control of the redox potential of actinide-containing solutions. A first inactive test demonstrated the feasibility of an Ag anode as a non-gassing auxiliary electrode in chloride solutions. (orig.)

  15. Characterization of cryogenic materials by x-ray absorption methods

    International Nuclear Information System (INIS)

    Heald, S.M.; Tranquada, J.M.

    1985-01-01

    X-ray absorption techniques have in recent years been developed into powerful probes of the electronic and structural properties of materials difficult to study by other techniques. In particular, the extended x-ray absorption fine structure (EXAFS) technique can be applied to a variety of cryogenic materials. Three examples are used to demonstrate the power of the technique. The first is the determination of the lattice location of dilute alloying additions such as Ta and Zr in Nb 3 Sn. The Ta additions are shown to reside predominately in Nb lattice sites, while Zr is not uniquely located at either Nb or Sn sites. In addition to structural information, temperature dependent EXAFS studies can be used to determine the rms deviations of atomic bond lengths, providing information about the temperature dependence of interatomic force constants. For Nb 3 Sn deviations are found from simple harmonic behavior at low temperatures which indicate a softening of the Nb-Sn bond strength. The final example is the study of interfacial properties in thin film systems. This is accomplished by making x-ray absorption measurements under conditions of total external reflection of the incident x-rays. As some examples show, this technique has great potential for studying interfacial reactions, a process used in the fabrication of many superconducting materials

  16. Theoretical approaches to x-ray absorption fine structure

    International Nuclear Information System (INIS)

    Rehr, J. J.; Albers, R. C.

    2000-01-01

    Dramatic advances in the understanding of x-ray absorption fine structure (XAFS) have been made over the past few decades, which have led ultimately to a highly quantitative theory. This review covers these developments from a unified multiple-scattering viewpoint. The authors focus on extended x-ray absorption fine structure (EXAFS) well above an x-ray edge, and, to a lesser extent, on x-ray absorption near-edge structure (XANES) closer to an edge. The discussion includes both formal considerations, derived from a many-electron formulation, and practical computational methods based on independent-electron models, with many-body effects lumped into various inelastic losses and energy shifts. The main conceptual issues in XAFS theory are identified and their relative importance is assessed; these include the convergence of the multiple-scattering expansion, curved-wave effects, the scattering potential, inelastic losses, self-energy shifts, and vibrations and structural disorder. The advantages and limitations of current computational approaches are addressed, with particular regard to quantitative experimental comparisons. (c) 2000 The American Physical Society

  17. Structural evaluation of reduced graphene oxide in graphene oxide during ion irradiation: X-ray absorption spectroscopy and in-situ sheet resistance studies

    Science.gov (United States)

    Saravanan, K.; Jayalakshmi, G.; Suresh, K.; Sundaravel, B.; Panigrahi, B. K.; Phase, D. M.

    2018-03-01

    We report the structural evolution of reduced graphene oxide (rGO) in graphene oxide (GO) flakes during 1 MeV Si+ ion irradiation. In-situ electrical resistivity measurements facilitate monitoring the sheet resistance with the increase in the fluence. The electrical sheet resistance of the GO flake shows the exponential decay behaviour with the increasing ion fluence. Raman spectra of the GO flake reveal the increase in the ID/IG ratio, indicating restoration of the sp2 network upon irradiation. The C/O ratio estimated from resonant Rutherford backscattering spectrometry analysis directly evidenced the reduction of oxygen moieties upon irradiation. C K-edge X-ray absorption near edge structure spectra reveal the restoration of C=C sp2-hybridized carbon atoms and the removal of oxygen-containing functional groups in the GO flake. STM data reveal the higher conductance in the rGO regime in comparison with the regime, where the oxygen functional groups are present. The experimental investigation demonstrates that the ion irradiation can be employed for efficient reduction of GO with tunable electrical and structural properties.

  18. Surface structure of alpha-Fe sub 2 O sub 3 nanocrystal observed by O K-edge X-ray absorption spectroscopy

    CERN Document Server

    Zhang, J; Ibrahim, K; Abbas, M I; Ju, X

    2003-01-01

    X-ray absorption near edge structure (XANES) spectra is used as a probe of surface structure of alpha-Fe sub 2 O sub 3 nanocrystal, prepared by sol-gel method. We present O K-edge XANES of alpha-Fe sub 2 O sub 3 in nanocrystal and bulk by total electron yield at the photoemission station of Beijing Synchrotron Radiation Facility. The spectrum of alpha-Fe sub 2 O sub 3 shows a splitting of the pre-edge structure, which is interpreted as two subsets of Fe 3d t sub 2 sub g and e sub g orbitals in oxygen octahedral (O sub h) crystal field, and is also sensitive to long-range order effects. However, no distinguishable splitting of the pre-edge peak of nanocrystal alpha-Fe sub 2 O sub 3 is observed. This suggests that there exists the distorted octahedral coordination around Fe sites and also the long-range disorder due to the surface as compared with bulk alpha-Fe sub 2 O sub 3.

  19. X-ray absorption spectroscopy of the chiral molecules fenchone, α-pinene, limonene and carvone in the C1s excitation region

    Energy Technology Data Exchange (ETDEWEB)

    Ozga, Christian, E-mail: ozga@physik.uni-kassel.de [Institute for Physics and CINSaT, University of Kassel, Heinrich-Plett Str. 40, 34132 Kassel (Germany); Jänkälä, Kari [Centre for Molecular Materials Research, University of Oulu, PO Box 3000, 90014 Oulu (Finland); Schmidt, Philipp; Hans, Andreas; Reiß, Philipp; Ehresmann, Arno; Knie, André [Institute for Physics and CINSaT, University of Kassel, Heinrich-Plett Str. 40, 34132 Kassel (Germany)

    2016-02-15

    Highlights: • Determination of the X-ray absorption spectra for two terpenoids and two terpenes. • Allocation of predominant or even site-selective excitation of stereocenters. • Fragment fluorescence spectra of the prototype molecules are identical. • Presented data can be used for future fluorescence circular dichroism experiments. - Abstract: Relative ionization cross sections and fluorescence intensities as functions of the exciting-photon energy were recorded for the chiral molecules carvone, α-pinene, limonene and fenchone after excitation by monochromatized synchrotron radiation with energies of the exciting-photons between 284 eV and 289 eV. At selected exciting-photon energies dispersed fragment fluorescence spectra in the wavelength range between 365 nm and 505 nm were obtained. Time dependent density functional theory (TD-DFT) computations were performed to analyze the experimentally observed resonance-structures. Comparison of the computed and recorded spectra demonstrates the possibility of a predominant or even specific excitation of one particular stereocenter site in a molecule with more than one stereocenter.

  20. Tris-amidoximate uranyl complexes via η2 binding mode coordinated in aqueous solution shown by X-ray absorption spectroscopy and density functional theory methods.

    Science.gov (United States)

    Zhang, Linjuan; Qie, Meiying; Su, Jing; Zhang, Shuo; Zhou, Jing; Li, Jiong; Wang, Yu; Yang, Shitong; Wang, Shuao; Li, Jingye; Wu, Guozhong; Wang, Jian Qiang

    2018-03-01

    The present study sheds some light on the long-standing debate concerning the coordination properties between uranyl ions and the amidoxime ligand, which is a key ingredient for achieving efficient extraction of uranium. Using X-ray absorption fine structure combined with theoretical simulation methods, the binding mode and bonding nature of a uranyl-amidoxime complex in aqueous solution were determined for the first time. The results show that in a highly concentrated amidoxime solution the preferred binding mode between UO 2 2+ and the amidoxime ligand is η 2 coordination with tris-amidoximate species. In such a uranyl-amidoximate complex with η 2 binding motif, strong covalent interaction and orbital hybridization between U 5f/6d and (N, O) 2p should be responsible for the excellent binding ability of the amidoximate ligand to uranyl. The study was performed directly in aqueous solution to avoid the possible binding mode differences caused by crystallization of a single-crystal sample. This work also is an example of the simultaneous study of local structure and electronic structure in solution systems using combined diagnostic tools.

  1. The electronic structure and magnetic interactions in the mixed transition-metal oxide La(Co,Ni)O{sub 3} studied by X-ray absorption spectroscopies

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Meng-Jie

    2016-11-11

    Transition-metal oxides have attracted a lot of attention because they exhibit a variety of intriguing physical properties. Among the transition-metal oxides, LaCoO{sub 3} is a very special compound which shows different spin states and spin-state transitions. Further, the physical properties can be controlled by changing temperature, replacement of rare-earth element, electron- or hole-doping, or by applying strain. The ground state of LaCoO{sub 3} is a non-magnetic insulator because the lowest energy configuration is t{sub 2g}{sup 6}e{sub g}{sup 0} (S = 0). However, the partial substitution of Co by Ni in La(Co,Ni)O{sub 3} (LCNO) will induce a ferromagnetic behavior. A number of models have been proposed for explaining the nature of the magnetic behavior in the past decades, but it is still a puzzle. In order to understand the origin of the ferromagnetism in La(Co,Ni)O{sub 3}, I have studied the electronic structure and magnetic interaction in this compound in a very direct way: by using X-ray absorption (XAS) and X-ray magnetic circular dichroism (XMCD) along with multiplet simulations. Samples were synthesized by the sol-gel method and structurally and magnetically characterized by XRD and SQUID. XAS clearly indicates a mixed-valence state for both Co and Ni, with both valences increasing monotonously with Ni content, x. While the gradual spin-state transition of Co{sup 3+} from low-spin (LS) to high-spin (HS) is preserved for low x it is suppressed in the high Ni-content samples. Regarding the spin configuration of Ni we find it stabilized in a ''mixed'' spin state, unlike the purely LS state of Ni in LaNiO{sub 3}. XMCD identifies the element-specific contributions to the magnetic moment and interactions. In particular, we find that it must be the coexistence of the HS state in both Co{sup 3+} and Ni{sup 3+} that induces t{sub 2g}-based ferromagnetic interaction via a ''double-exchange-like'' mechanism. Other species

  2. Probing the influence of the center atom coordination structure in iron phthalocyanine multi-walled carbon nanotube-based oxygen reduction reaction catalysts by X-ray absorption fine structure spectroscopy

    Science.gov (United States)

    Peng, Yingxiang; Li, Zhipan; Xia, Dingguo; Zheng, Lirong; Liao, Yi; Li, Kai; Zuo, Xia

    2015-09-01

    Three different pentacoordinate iron phthalocyanine (FePc) electrocatalysts with an axial ligand (pyridyl group, Py) anchored to multi-walled carbon nanotubes (MWCNTs) are prepared by a microwave method as high performance composite electrocatalysts (FePc-Py/MWCNTs) for the oxygen reduction reaction (ORR). For comparison, tetracoordinate FePc electrocatalysts without an axial ligand anchored to MWCNTs (FePc/MWCNTs) are assembled in the same way. Ultraviolet-visible spectrophotometry (UV-Vis), Raman spectroscopy (RS), and high-resolution transmission electron microscopy (HRTEM) are used to characterize the obtained electrocatalysts. The electrocatalytic activity of the samples is measured by linear sweep voltammetry (LSV), and the onset potential of all of the FePc-Py/MWCNTs electrocatalysts is found to be more positive than that of their FePc/MWCNTs counterparts. X-ray photoelectron spectroscopy (XPS) and X-ray absorption fine structure (XAFS) spectroscopy are employed to elucidate the relationship between molecular structure and electrocatalytic activity. XPS indicates that higher concentrations of Fe3+ and pyridine-type nitrogen play critical roles in determining the electrocatalytic ORR activity of the samples. XAFS spectroscopy reveals that the FePc-Py/MWCNTs electrocatalysts have a coordination geometry around Fe that is closer to the square pyramidal structure, a higher concentration of Fe3+, and a smaller phthalocyanine ring radius compared with those of FePc/MWCNTs.

  3. Chemical shift of Mn and Cr K-edges in X-ray absorption

    Indian Academy of Sciences (India)

    ... Lecture Workshops · Refresher Courses · Symposia · Live Streaming. Home; Journals; Bulletin of Materials Science; Volume 36; Issue 6. Chemical shift of Mn and Cr K-edges in X-ray absorption spectroscopy with synchrotron radiation. D Joseph A K Yadav S N Jha D Bhattacharyya. Volume 36 Issue 6 November 2013 pp ...

  4. On the initial corrosion mechanism of zirconium alloy: Interaction of oxygen and water with Zircaloy at room temperature and 450 C evaluated by x-ray absorption spectroscopy and photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Doebler, U.; Knop, A.

    1994-01-01

    The initial stages of zirconium oxide formation on Zircaloy after water (H 2 O) and oxygen (O 2 ) exposures have been investigated in situ using photoelectron spectroscopy and X-ray-absorption spectroscopy. The reactivity of the zirconium alloy with O 2 at room temperature is about 1,000 times higher than for H 2 O. Up to 100 L (1 L = 1 Langmuir unit = 1 · 10 -6 mbar · s) H 2 O exposure, the reactivity of the zirconium alloy at 450 C is comparable to the room temperature reaction. At higher H 2 O exposure, a sharp increase in the reaction rate for the high-temperature oxidation is observed. From the energy position of the Zr 3d photo emission line and their oxygen-induced chemical shifts, one can really follow the formation of the oxide films. Two different substoichiometric oxides were found during reaction with water. Suboxide (1) is located at the zirconium/zirconium-oxide interface. Subsequently, a Suboxide (2) is concluded from the chemical shift of the zirconium photoelectrons. After an oxide thickness of 2 nm, the stoichiometric ZrO 2 phase is not yet developed

  5. Speciation of Zinc in ash investigated by X-ray absorption spectroscopy; Zinks foerekomstformer i aska studerade med en roentgenabsorptionsspektrometrisk metod

    Energy Technology Data Exchange (ETDEWEB)

    Steenari, Britt-Marie; Noren, Katarina

    2008-06-15

    Direct identification of trace metal compounds in solid materials is difficult to achieve due to the detection limits of available analytical methods. Although zinc is the most abundant trace metal in combustion residues, the number of publications dealing with its direct speciation is small. Struis and co-workers have published an investigation where they used Extended X-ray Absorption Fine Structure spectroscopy (EXAFS) measurements to identify zinc compounds in municipal solid waste incineration fly ash. The EXAFS technique has been used more often for speciation of Zn in contaminated soil. EXAFS data for farm soil samples showed that zinc was most commonly sequestered in layer silicates, but soil particles containing zinc sulphide, zinc chromite and zinc phosphate were also found. Generally, published results show that zinc after being mobilised in a soil, has a clear tendency to be sequestered in silicates, as sulphides or, if there is phosphate available, as phosphate. The aim of the work presented in this work was to use the EXAFS method to show how zinc in chemically bound in ash from woody fuels and from municipal solid waste (MSW). The results can be used for evaluations of the possible toxicity of ash and in predictions of the leaching of zinc from ash. The investigation comprised dry ashes from two fluidised bed combustors fired with forestry litter, bark and other wood fuels, moistened and aged wood ashes and dry ashes from three MSW incinerators: one fluidised bed combustor and two stoker fired combustors. The spectroscopic measurements were carried out at the beam line I811 in the Swedish national synchrotron facility Maxlab at Lund University. The results showed that the lowest concentration of Zn in ash for which it is possible to get any information about the nearest neighbour atoms around zinc is about 500 mg Zn per kg dry ash. If the concentration is higher than 1000 mg/ kg it is possible to obtain information, not only about the nearest

  6. X-ray absorption fine structure (XAFS) studies of cobalt silicide thin films

    International Nuclear Information System (INIS)

    Naftel, S.J.; Coulthard, I.; Hu, Y.; Sham, T.K.; Zinke-Allmang, M.

    1998-01-01

    Cobalt silicide thin films, prepared on Si(100) wafers, have been studied by X-ray absorption near edge structures (XANES) at the Si K-, L 2,3 - and Co K-edges utilizing both total electron (TEY) and fluorescence yield (FLY) detection as well as extended X-ray absorption fine structure (EXAFS) at the Co K-edge. Samples made using DC sputter deposition on clean Si surfaces and MBE were studied along with a bulk CoSi 2 sample. XANES and EXAFS provide information about the electronic structure and morphology of the films. It was found that the films studied have essentially the same structure as bulk CoSi 2 . Both the spectroscopy and materials characterization aspects of XAFS (X-ray absorption fine structures) are discussed

  7. Absorption correction factor in X-ray fluorescent quantitative analysis

    International Nuclear Information System (INIS)

    Pimjun, S.

    1994-01-01

    An experiment on absorption correction factor in X-ray fluorescent quantitative analysis were carried out. Standard samples were prepared from the mixture of Fe 2 O 3 and tapioca flour at various concentration of Fe 2 O 3 ranging from 5% to 25%. Unknown samples were kaolin containing 3.5% to-50% of Fe 2 O 3 Kaolin samples were diluted with tapioca flour in order to reduce the absorption of FeK α and make them easy to prepare. Pressed samples with 0.150 /cm 2 and 2.76 cm in diameter, were used in the experiment. Absorption correction factor is related to total mass absorption coefficient (χ) which varied with sample composition. In known sample, χ can be calculated by conveniently the formula. However in unknown sample, χ can be determined by Emission-Transmission method. It was found that the relationship between corrected FeK α intensity and contents of Fe 2 O 3 in these samples was linear. This result indicate that this correction factor can be used to adjust the accuracy of X-ray intensity. Therefore, this correction factor is essential in quantitative analysis of elements comprising in any sample by X-ray fluorescent technique

  8. Kinoform optics applied to X-ray photon correlation spectroscopy.

    Science.gov (United States)

    Sandy, A R; Narayanan, S; Sprung, M; Su, J-D; Evans-Lutterodt, K; Isakovic, A F; Stein, A

    2010-05-01

    Moderate-demagnification higher-order silicon kinoform focusing lenses have been fabricated to facilitate small-angle X-ray photon correlation spectroscopy (XPCS) experiments. The geometric properties of such lenses, their focusing performance and their applicability for XPCS measurements are described. It is concluded that one-dimensional vertical X-ray focusing via silicon kinoform lenses significantly increases the usable coherent flux from third-generation storage-ring light sources for small-angle XPCS experiments.

  9. First results from the high-brightness x-ray spectroscopy beamline at ALS

    Energy Technology Data Exchange (ETDEWEB)

    Perera, R.C.C.; Ng, W.; Jones, G. [Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    Beamline 9.3.1 at the Advanced Light Source (ALS) is a windowless beamline, covering the 1-6 keV photon-energy range, designed to achieve the goal of high brightness at the sample for use in the X-ray Atomic and Molecular Spectroscopy (XAMS) science, surface and interface science, biology and x-ray optical development programs at ALS. X-ray absorption and time of flight photo emission measurements in 2 - 5 keV photon energy in argon along with the flux, resolution, spot size and stability of the beamline will be discussed. Prospects for future XAMS measurements will also be presented.

  10. Simultaneous Speciation, Structure, and Equilibrium Constant Determination in the Ni2+-EDTA-CN- Ternary System via High-Resolution Laboratory X-ray Absorption Fine Structure Spectroscopy and Theoretical Calculations.

    Science.gov (United States)

    Bajnóczi, Éva G; Németh, Zoltán; Vankó, György

    2017-11-20

    Even quite simple chemical systems can involve many components and chemical states, and sometimes it can be very difficult to differentiate them by their hardly separable physical-chemical properties. The Ni II -EDTA-CN - (EDTA = ethylenediaminetetraacetic acid) ternary system is a good example for this problem where, in spite of its fairly simple components and numerous investigations, several molecular combinations can exist, all of them not having been identified unambiguously yet. In order to achieve a detailed understanding of the reaction steps and chemical equilibria, methods are required in which the structural transitions in the different reaction steps can be followed via element-selective complex spectral feature sets. With the help of our recently developed von Hámos type high-resolution laboratory X-ray absorption spectrometer, both the structural variations and stability constants of the forming complexes were determined from the same measurement series, proving that X-ray absorption spectroscopy can be considered as a multifaced, table-top tool in coordination chemistry. Furthermore, with the help of theoretical calculations, independent structural evidence was also given for the formation of the [NiEDTA(CN)] 3- mixed complex.

  11. Multiple scattering theory of X-ray absorption. A review

    International Nuclear Information System (INIS)

    Fonda, L.

    1991-11-01

    We review the basic elements of the theory of X-ray absorption using the tools provided by the theory of multiple scattering. A momentum space approach of clear physical insight is used where the final formulas expressing EXAFS and XANES, i.e. the structures appearing in the absorption coefficient above the edge of a deep core level threshold, are given in terms of eigenstates of the photoelectron momentum. A simple graphic representation is given for the multiple scattering function. (author). 38 refs, 4 figs, 1 tab

  12. Stimulated X-Ray Emission Spectroscopy in Transition Metal Complexes

    Science.gov (United States)

    Kroll, Thomas; Weninger, Clemens; Alonso-Mori, Roberto; Sokaras, Dimosthenis; Zhu, Diling; Mercadier, Laurent; Majety, Vinay P.; Marinelli, Agostino; Lutman, Alberto; Guetg, Marc W.; Decker, Franz-Josef; Boutet, Sébastien; Aquila, Andy; Koglin, Jason; Koralek, Jake; DePonte, Daniel P.; Kern, Jan; Fuller, Franklin D.; Pastor, Ernest; Fransson, Thomas; Zhang, Yu; Yano, Junko; Yachandra, Vittal K.; Rohringer, Nina; Bergmann, Uwe

    2018-03-01

    We report the observation and analysis of the gain curve of amplified K α x-ray emission from solutions of Mn(II) and Mn(VII) complexes using an x-ray free electron laser to create the 1 s core-hole population inversion. We find spectra at amplification levels extending over 4 orders of magnitude until saturation. We observe bandwidths below the Mn 1 s core-hole lifetime broadening in the onset of the stimulated emission. In the exponential amplification regime the resolution corrected spectral width of ˜1.7 eV FWHM is constant over 3 orders of magnitude, pointing to the buildup of transform limited pulses of ˜1 fs duration. Driving the amplification into saturation leads to broadening and a shift of the line. Importantly, the chemical sensitivity of the stimulated x-ray emission to the Mn oxidation state is preserved at power densities of ˜1020 W /cm2 for the incoming x-ray pulses. Differences in signal sensitivity and spectral information compared to conventional (spontaneous) x-ray emission spectroscopy are discussed. Our findings build a baseline for nonlinear x-ray spectroscopy for a wide range of transition metal complexes in inorganic chemistry, catalysis, and materials science.

  13. Phase-dependent absorption features in X-ray spectra of X-ray Dim Isolated Neutron Stars

    Science.gov (United States)

    Borghese, A.; Rea, N.; Coti Zelati, F.; Turolla, R.; Tiengo, A.; Zane, S.

    2017-12-01

    A detailed phase-resolved spectroscopy of archival XMM-Newton observations of X-ray Dim Isolated Neutron Stars (XDINSs) led to the discovery of narrow and strongly phase-dependent absorption features in two of these sources. The first was discovered in the X-ray spectrum of RX J0720.4-3125, followed by a new possible candidate in RX J1308.6+2127. Both spectral lines have similar properties: they are detected for only ˜ 20% of the rotational cycle and appear to be stable over the timespan covered by the observations. We performed Monte Carlo simulations to test the significance of these phase-variable features and in both cases the outcome has confirmed the detection with a confidence level > 4.6σ. Because of the narrow width and the strong dependence on the pulsar rotational phase, the most likely interpretation for these spectral features is in terms of resonant proton cyclotron absorption scattering in a confined high-B structure close to the stellar surface. Within the framework of this interpretation, our results provide evidence for deviations from a pure dipole magnetic field on small scales for highly magnetized neutron stars and support the proposed scenario of XDINSs being aged magnetars, with a strong non-dipolar crustal B-field component.

  14. Study of oxidation states of the transition metals in a series of Prussian blue analogs using x-ray absorption near edge structure (XANES) spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Adak, S. [Department of Physics, New Mexico State University, Las Cruces, NM, 88003 (United States); Hartl, M., E-mail: monika.hartl@esss.se [European Spallation Source ESS AB, 22100, Lund (Sweden); Manuel Lujan Jr. Neutron Scattering Center (LANSCE-LC), Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Daemen, L. [Spallation Neutron Source, Oak Ridge National Laboratory, Oak Ridge, TN, 37830 (United States); Manuel Lujan Jr. Neutron Scattering Center (LANSCE-LC), Los Alamos National Laboratory, Los Alamos, NM, 87545 (United States); Fohtung, E.; Nakotte, H. [Department of Physics, New Mexico State University, Las Cruces, NM, 88003 (United States)

    2017-01-15

    Highlights: • Systematic XANES measurements on Prussian blue analogs shows oxidation state of transition metals. • Cobal-iron bimetallic hexacyanometallates show unexpected oxidation states. • Iron(II) ions in hexacyanometallates(III) show varying spin state depending on their bond to the “N” end or “C” end of the cyanide ligand. • Thermal expansion coefficients have been linked to the XANES results. - Abstract: There have been renewed interests in metal-organic framework classes of materials such as Prussian blue analogues (PBAs) due to their potential usage in energy storage applications. In particular, due to their high surface areas, controllable structures and excellent electrochemical properties, PBAs such as hexacyanometalates M{sup II}{sub 3}[A{sup III}(CN){sub 6}]{sub 2*}nH{sub 2}O (M = Mn, Fe, Co, Ni, Cu, Zn; A = Co, Fe, Cr; n = no. of water molecules present), M{sup II}{sub 2}[Fe{sup II}(CN){sub 6}]{sub 2*}nH{sub 2}O (M = Mn, Co, Ni, Cu, Zn) and mixed hexacyanometalates(III) (Fe{sub 1-x}Co{sub x}){sub 3}[B{sup III}(CN){sub 6}]{sub 2}·nH{sub 2}O (x = 0.25, 0.5, 0.75; B = Co, Fe) could have possible usage as a new class of cathode and even anode materials for rechargeable batteries. Detailed knowledge of the oxidation states of the transition metals in PBAs is required to improve efficiency and durability of such devices. Furthermore, a link between the thermal expansion observed in these materials and the oxidation state of the transition metal is of interest to synthesize materials with a desired thermal expansion behavior, Here we demonstrate the use of Synchrotron based X-ray absorption near-edge structure (XANES) spectra to identify transition metal oxidation states. Our analysis reveals the presence of divalent, trivalent and/or mixed valence transition metals in the materials as well as high-spin and low-spin complexes.

  15. Future projects of light kaonic atom X-ray spectroscopy

    International Nuclear Information System (INIS)

    Tatsuno, H.; Bazzi, M.; Beer, G.; Bellotti, G.; Berucci, C.; Bragadireanu, A.M.; Bosnar, D.; Cargnelli, M.; Curceanu, C.; Butt, A.D.; D’Uffizi, A.; Fiorini, C.; Ghio, F.; Guaraldo, C.; Hayano, R.S.; Iliescu, M.; Ishiwatari, T.; Iwasaki, M.; Sandri, P. Levi; Marton, J.; Okada, S.; Pietreanu, D.; Piscicchia, K.; Vidal, A. Romero; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D.L.; Sirghi, F.; Doce, O. Vazquez; Widmann, E.; Zmeskal, J.

    2016-01-01

    X-ray spectroscopy of light kaonic atoms is a unique tool to provide precise information on the fundamental K̄N interaction at the low-energy limit and the in-medium nuclear interaction of K"−. The future experiments of kaonic deuterium strong-interaction shift and width (SIDDHARTA-2 and J-PARC E57) can extract the isospin dependent K"−N interaction at threshold. The high-resolution X-ray spectroscopy of kaonic helium with microcalorimeters (J-PARC E62) has the possibility to solve the long-standing potential-strength problem of the attractive K"−-nucleus interaction. Here, the recent experimental results and the future projects of X-ray spectroscopy of light kaonic atoms are presented.

  16. Redox chemistry of a binary transition metal oxide (AB2O4): a study of the Cu(2+)/Cu(0) and Fe(3+)/Fe(0) interconversions observed upon lithiation in a CuFe2O4 battery using X-ray absorption spectroscopy.

    Science.gov (United States)

    Cama, Christina A; Pelliccione, Christopher J; Brady, Alexander B; Li, Jing; Stach, Eric A; Wang, Jiajun; Wang, Jun; Takeuchi, Esther S; Takeuchi, Kenneth J; Marschilok, Amy C

    2016-06-22

    Copper ferrite, CuFe2O4, is a promising candidate for application as a high energy electrode material in lithium based batteries. Mechanistic insight on the electrochemical reduction and oxidation processes was gained through the first X-ray absorption spectroscopic study of lithiation and delithiation of CuFe2O4. A phase pure tetragonal CuFe2O4 material was prepared and characterized using laboratory and synchrotron X-ray diffraction, Raman spectroscopy, and transmission electron microscopy. Ex situ X-ray absorption spectroscopy (XAS) measurements were used to study the battery redox processes at the Fe and Cu K-edges, using X-ray absorption near-edge structure (XANES), extended X-ray absorption fine structure (EXAFS), and transmission X-ray microscopy (TXM) spectroscopies. EXAFS analysis showed upon discharge, an initial conversion of 50% of the copper(ii) to copper metal positioned outside of the spinel structure, followed by a migration of tetrahedral iron(iii) cations to octahedral positions previously occupied by copper(ii). Upon charging to 3.5 V, the copper metal remained in the metallic state, while iron metal oxidation to iron(iii) was achieved. The results provide new mechanistic insight regarding the evolution of the local coordination environments at the iron and copper centers upon discharging and charging.

  17. X-ray optical analyses with X-Ray Absorption Package (XRAP)

    International Nuclear Information System (INIS)

    Wang, Zhibi; Kuzay, T.M.; Dejus, R.; Grace, T.

    1994-01-01

    This paper presents an X-Ray Absorption Package (XRAP) and the theoretical background for this program. XRAP is a computer code developed for analysis of optical elements in synchrotron radiation facilities. Two main issues are to be addressed: (1) generating BM (bending magnet) and ID (insertion device) spectrum and calculating their absorption in media, especially in such structural forms as variable thickness windows/filters and crystals; and (2) providing a finite difference engine for fast but sophisticated thermal and stress analyses for optical elements, such as windows and filters. Radiation cooling, temperature-dependent material properties (such as thermal conductivity and thermal expansion coefficient) etc. are taken into account in the analyses. For very complex geometry, an interface is provided directly to finite element codes such as ANSYS. Some of the present features built into XRAP include: (1) generation of BM and ID spectra; (2) photon absorption analysis of optical elements including filters, windows and mirrors, etc.; (3) heat transfer and thermal stress analyses of windows and filters and their buckling check; (4) user-friendly graphical-interface that is based on the state-of-the-art technology of GUI and X-window systems, which can be easily ported to other computer platforms; (5) postscript file output of either black/white or colored graphics for total/absorbed power, temperature, stress, spectra, etc

  18. Resonant X-ray emission spectroscopy in Dy compounds

    International Nuclear Information System (INIS)

    Tanaka, Satoshi; Okada, Kozo; Kotani, Akio.

    1994-01-01

    The excitation spectrum of the L 3 -M 5 X-ray emission of Dy compounds in the pre-edge region of Dy L 3 X-ray absorption near edge structure (L 3 -XANES) is theoretically investigated based upon the coherent second order optical formula with multiplet coupling effects. The spectral broadening of the excitation spectrum is determined by the M 5 core hole lifetime, being free from the L 3 core hole lifetime. The fine pre-edge structure of the L 3 edge due to the 2p→4f quadrupole transition can be seen in the excitation spectrum, while this structure is invisible in the conventional XANES, in agreement with the recent experimental results. We clarify the conditions for the excitation spectrum to be regarded as the absorption spectrum with a smaller width. The resonant X-ray emission spectra for various incident photon energies around the L 3 edge are also calculated. (author)

  19. Time-resolved X-ray spectroscopies of chemical systems: New perspectives

    Directory of Open Access Journals (Sweden)

    Majed Chergui

    2016-05-01

    Full Text Available The past 3–5 years have witnessed a dramatic increase in the number of time-resolved X-ray spectroscopic studies, mainly driven by novel technical and methodological developments. The latter include (i the high repetition rate optical pump/X-ray probe studies, which have greatly boosted the signal-to-noise ratio for picosecond (ps X-ray absorption spectroscopy studies, while enabling ps X-ray emission spectroscopy (XES at synchrotrons; (ii the X-ray free electron lasers (XFELs are a game changer and have allowed the first femtosecond (fs XES and resonant inelastic X-ray scattering experiments to be carried out; (iii XFELs are also opening the road to the development of non-linear X-ray methods. In this perspective, I will mainly focus on the most recent technical developments and briefly address some examples of scientific questions that have been addressed thanks to them. I will look at the novel opportunities in the horizon.

  20. Pixel detectors for x-ray imaging spectroscopy in space

    International Nuclear Information System (INIS)

    Treis, J; Andritschke, R; Hartmann, R; Herrmann, S; Holl, P; Lauf, T; Lechner, P; Lutz, G; Meidinger, N; Porro, M; Richter, R H; Schopper, F; Soltau, H; Strueder, L

    2009-01-01

    Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 x 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

  1. Pixel detectors for x-ray imaging spectroscopy in space

    Science.gov (United States)

    Treis, J.; Andritschke, R.; Hartmann, R.; Herrmann, S.; Holl, P.; Lauf, T.; Lechner, P.; Lutz, G.; Meidinger, N.; Porro, M.; Richter, R. H.; Schopper, F.; Soltau, H.; Strüder, L.

    2009-03-01

    Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 × 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

  2. Pixel detectors for x-ray imaging spectroscopy in space

    Energy Technology Data Exchange (ETDEWEB)

    Treis, J; Andritschke, R; Hartmann, R; Herrmann, S; Holl, P; Lauf, T; Lechner, P; Lutz, G; Meidinger, N; Porro, M; Richter, R H; Schopper, F; Soltau, H; Strueder, L [MPI Semiconductor Laboratory, Otto-Hahn-Ring 6, D-81739 Munich (Germany)], E-mail: jft@hll.mpg.de

    2009-03-15

    Pixelated semiconductor detectors for X-ray imaging spectroscopy are foreseen as key components of the payload of various future space missions exploring the x-ray sky. Located on the platform of the new Spectrum-Roentgen-Gamma satellite, the eROSITA (extended Roentgen Survey with an Imaging Telescope Array) instrument will perform an imaging all-sky survey up to an X-ray energy of 10 keV with unprecedented spectral and angular resolution. The instrument will consist of seven parallel oriented mirror modules each having its own pnCCD camera in the focus. The satellite born X-ray observatory SIMBOL-X will be the first mission to use formation-flying techniques to implement an X-ray telescope with an unprecedented focal length of around 20 m. The detector instrumentation consists of separate high- and low energy detectors, a monolithic 128 x 128 DEPFET macropixel array and a pixellated CdZTe detector respectively, making energy band between 0.5 to 80 keV accessible. A similar concept is proposed for the next generation X-ray observatory IXO. Finally, the MIXS (Mercury Imaging X-ray Spectrometer) instrument on the European Mercury exploration mission BepiColombo will use DEPFET macropixel arrays together with a small X-ray telescope to perform a spatially resolved planetary XRF analysis of Mercury's crust. Here, the mission concepts and their scientific targets are briefly discussed, and the resulting requirements on the detector devices together with the implementation strategies are shown.

  3. Natural nanomaterials : reappraising the elusive structure of the nano-sized mineral ferrihydrite through X-Ray absorption spectroscopy at the iron K-edge

    OpenAIRE

    Figueiredo, M. Ondina; Silva, Teresa Pereira; Veiga, João Pedro

    2013-01-01

    Ferrihydrite is natural ferric oxyhydroxide occurring exclusively nanocrystalline. With ideal formula 5 Fe2 O3 . 9 H2 O, ferrihydrite is quite abundant in sediments, weathering crusts and mine wastes, being characteristic of red pre-soils formed by loose weathered rock plus mineral debris (regoliths) and commonly designated as “2-line” or “6-line” on the basis of the broadened maxima observed in the X-ray diffraction pattern. Synthetic nanocrystalline “6-line” ferrihydrite was...

  4. Key electronic states in lithium battery materials probed by soft X-ray spectroscopy

    International Nuclear Information System (INIS)

    Yang, Wanli; Liu, Xiaosong; Qiao, Ruimin; Olalde-Velasco, Paul; Spear, Jonathan D.; Roseguo, Louis; Pepper, John X.; Chuang, Yi-de; Denlinger, Jonathan D.; Hussain, Zahid

    2013-01-01

    Highlights: •Key electronic states in battery materials revealed by soft X-ray spectroscopy. •Soft X-ray absorption consistently probes Mn oxidation states in different systems. •Soft X-ray absorption and emission fingerprint battery operations in LiFePO 4 . •Spectroscopic guidelines for selecting/optimizing polymer materials for batteries. •Distinct SEI formation on same electrode material with different crystal orientations. -- Abstract: The formidable challenges for developing a safe, low-cost, high-capacity, and high-power battery necessitate employing advanced tools that are capable of directly probing the key electronic states relevant to battery performance. Synchrotron based soft X-ray spectroscopy directly measures both the occupied and unoccupied states in the vicinity of the Fermi level, including transition-metal-3d and anion-p states. This article presents the basic concepts on how fundamental physics in electronic structure could provide valuable information for lithium-ion battery applications. We then discuss some of our recent studies on transition-metal oxide based cathodes, silicon based anode, and solid-electrolyte-interphase through soft X-ray absorption and emission spectroscopy. We argue that spectroscopic results reveal the evolution of electronic states for fingerprinting, understanding, and optimizing lithium-ion battery operations

  5. Pseudocapacitance of MnO{sub 2} originates from reversible insertion/desertion of thiocyanate anions studied using in situ X-ray absorption spectroscopy in ionic liquid electrolyte

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Ming-Tsung; Tsai, Wen-Ta; Chang, Jeng-Kuei [Department of Materials Science and Engineering, National Cheng Kung University, 1 University Road, Tainan (China); Deng, Ming-Jay; Cheng, Hui-Fang; Sun, I-Wen [Department of Chemistry, National Cheng Kung University, 1 University Road, Tainan (China)

    2010-02-01

    Charge storage mechanisms of electrodeposited MnO{sub 2} in various aprotic ionic liquids (ILs) are studied using in situ X-ray absorption spectroscopy (XAS). The analytical results show that a unique thiocyanate (SCN{sup -}) anion can reversibly insert/desert into/from the tunnels between the [MnO{sub 6}] octahedral subunits depending on the applied potential. This process charge compensates the Mn{sup 3+}/Mn{sup 4+} redox transition upon charging-discharging and thus contributes to an ideal pseudocapacitive behavior of the MnO{sub 2} electrode. The present work would open up a route for developing a novel oxide-based supercapacitor, with high cell-voltage, high thermal stability, and high safety, incorporating IL electrolytes. (author)

  6. New experimental perspectives for soft x-ray absorption spectroscopies at ultra-low temperatures below 50 mK and in high magnetic fields up to 7 T

    International Nuclear Information System (INIS)

    Beeck, T.; Baev, I.; Gieschen, S.; Meyer, H.; Meyer, S.; Palutke, S.; Martins, M.; Feulner, P.; Uhlig, K.; Wurth, W.

    2016-01-01

    A new ultra-low temperature experiment including a superconducting vector magnet has been developed for soft x-ray absorption spectroscopy experiments at third generation synchrotron light sources. The sample is cooled below 50 mK by a cryogen free "3He-"4He dilution refrigerator. At the same time, magnetic fields of up to ±7 T in the horizontal direction and ±0.5 T in the vertical direction can be applied by a superconducting vector magnet. The setup allows to study ex situ and in situ prepared samples, offered by an attached UHV preparation chamber with load lock. The transfer of the prepared samples between the preparation section and the dilution refrigerator is carried out under cryogenic temperatures. First commissioning studies have been carried out at the Variable Polarization XUV Beamline P04 at PETRA III and the influence of the incident photon beam to the sample temperature has been studied.

  7. X-ray absorption spectroscopy study on SiC-side interface structure of SiO2–SiC formed by thermal oxidation in dry oxygen

    Science.gov (United States)

    Isomura, Noritake; Kosaka, Satoru; Kataoka, Keita; Watanabe, Yukihiko; Kimoto, Yasuji

    2018-06-01

    Extended X-ray absorption fine structure (EXAFS) spectroscopy is demonstrated to measure the fine atomic structure of SiO2–SiC interfaces. The SiC-side of the interface can be measured by fabricating thin SiO2 films and using SiC-selective EXAFS measurements. Fourier transforms of the oscillations of the EXAFS spectra correspond to radial-structure functions and reveal a new peak of the first nearest neighbor of Si for m-face SiC, which does not appear in measurements of the Si-face. This finding suggests that the m-face interface could include a structure with shorter Si–C distances. Numerical calculations provide additional support for this finding.

  8. Electron-probe microanalysis: x-ray spectroscopy

    International Nuclear Information System (INIS)

    1987-01-01

    The main principles on X-ray, energy and wave length dispersive spectroscopy are reviewed. In order to allow the choice of the best operating conditions, the importance of the regulation and control systems is underlined. Emission theory, X-rays nature and its interaction with matter and electrons in the matter is shown. The structure, operating procedures and necessary electronics (single channel - analysis chain) automatic-control system for the threshold-energies discrimination and the energy distribution visualization) associated to the wavelength dispersive spectroscopy are described. The focusing control, resolution, influence of chemical bonds and multilayer-structure monochromators relaled to wavelength dispersive spectroscopy are studied. Concerning the energy-dispersive spectroscopy, the detector, preamplifier, amplifier, analog-digital converter, as well as the utilization and control of the spectrometer are described. Problems and instrumental progress on energy-dispersive spectroscopy related to the electronic-noise control, charge collection and light-elements detection are discussed [fr

  9. NSLS [National Synchrotron Light Source] X-19A beamline performance for x-ray absorption measurements

    International Nuclear Information System (INIS)

    Yang, C.Y.; Penner-Hahn, J.E.; Stefan, P.M.

    1989-01-01

    Characterization of the X-19A beamline at the National Synchrotron Light Source (NSLS) is described. The beamline is designed for high resolution x-ray absorption spectroscopy over a wide energy range. All of the beamline optical components are compatible with ultrahigh vacuum (UHV) operation. This permits measurements to be made in a window-less mode, thereby facilitating lower energy (<4 KeV) studies. To upgrade the beamline performance, several possible improvements in instrumentation and practice are discussed to increase photon statistics with an optimum energy resolution, while decreasing the harmonic contamination and noise level. A special effort has been made to improve the stability and UHV compatibility of the monochromator system. Initial x-ray absorption results demonstrate the capabilities of this beamline for x-ray absorption studies of low Z elements (e.g. S) in highly dilute systems. The future use of this beamline for carrying out various x-ray absorption experiments is presented. 10 refs., 4 figs

  10. Nuclear and x-ray spectroscopy with radioactive sources

    International Nuclear Information System (INIS)

    Fink, R.W.

    1977-01-01

    Research in nuclear chemistry for 1977 is reviewed. The greatest part of the effort was directed to nuclear spectroscopy (systematics, models, experimental studies), but some work was also done involving fast neutrons and x rays from radioactive sources. Isotopes of Tl, Hg, Au, and Eu were studied in particular. Personnel and publications lists are also included. 5 figures, 1 table

  11. Auger electron and X-ray spectroscopy of hollow atoms

    NARCIS (Netherlands)

    Morgenstern, R; Johnson, RL; Schmidtbocking, H; Sonntag, BF

    1997-01-01

    Hollow atoms as formed during collisions of multiply charged ions on metallic, semiconducting and insulating surfaces have in recent years successfully been investigated by various spectroscopic methods: low- and high-resolution X-ray spectroscopy as well as high resolution Auger electron

  12. Unitary bases for x-ray photoelectron spectroscopy

    International Nuclear Information System (INIS)

    Patterson, C.W.; Harter, W.G.; Schneider, W.D.

    1979-01-01

    A Gelfand basis is used to derive the coefficients of fractional parentage (CFP's) used to calculate intensities for x-ray photoelectron spectroscopy of atoms. Using associated Gelfand bases, we show that it is easy to derive the Racah CFP relations between particles and holes

  13. X-ray Photoelectron Spectroscopy Database (Version 4.1)

    Science.gov (United States)

    SRD 20 X-ray Photoelectron Spectroscopy Database (Version 4.1) (Web, free access)   The NIST XPS Database gives access to energies of many photoelectron and Auger-electron spectral lines. The database contains over 22,000 line positions, chemical shifts, doublet splittings, and energy separations of photoelectron and Auger-electron lines.

  14. Single atom identification by energy dispersive x-ray spectroscopy

    International Nuclear Information System (INIS)

    Lovejoy, T. C.; Dellby, N.; Krivanek, O. L.; Ramasse, Q. M.; Falke, M.; Kaeppel, A.; Terborg, R.; Zan, R.

    2012-01-01

    Using aberration-corrected scanning transmission electron microscope and energy dispersive x-ray spectroscopy, single, isolated impurity atoms of silicon and platinum in monolayer and multilayer graphene are identified. Simultaneously acquired electron energy loss spectra confirm the elemental identification. Contamination difficulties are overcome by employing near-UHV sample conditions. Signal intensities agree within a factor of two with standardless estimates.

  15. X-ray imaging and spectroscopy of individual cobalt nanoparticles using photoemission electron microscopy

    International Nuclear Information System (INIS)

    Fraile Rodriguez, A.; Nolting, F.; Bansmann, J.; Kleibert, A.; Heyderman, L.J.

    2007-01-01

    Photoemission electron microscopy (PEEM) was employed for X-ray imaging and absorption spectroscopy of individual cobalt nanoparticles as small as 8 nm grown using an arc ion cluster source. Using lithographic markers on the samples we were able to identify the same particles with PEEM and scanning electron microscopy. Significant variations in the shape of the X-ray absorption spectra between different cobalt particles were detected. Furthermore, our data suggest that distinctive spectral information about the individual particles, such as the quenching of oxide-related features and changes in the cobalt L 3 -edge intensity, cancel out and cannot be detected in the measurement over an ensemble of particles

  16. State-dependent electron delocalization dynamics at the solute-solvent interface: soft-x-ray absorption spectroscopy and ab initio calculations.

    Science.gov (United States)

    Bokarev, Sergey I; Dantz, Marcus; Suljoti, Edlira; Kühn, Oliver; Aziz, Emad F

    2013-08-23

    Nonradiative decay channels in the L-edge fluorescence yield spectra from transition-metal-aqueous solutions give rise to spectral distortions with respect to x-ray transmission spectra. Their origin is unraveled here using partial and inverse partial fluorescence yields on the microjet combined with multireference ab initio electronic structure calculations. Comparing Fe2+, Fe3+, and Co2+ systems we demonstrate and quantify unequivocally the state-dependent electron delocalization within the manifold of d orbitals as one origin of this observation.

  17. Comparison of the trace analysis of heavy metal aerosols by means of atom absorption spectroscopy and proton-induced X-ray spectrometry

    International Nuclear Information System (INIS)

    Nottrodt, K.H.; Georgii, H.W.; Groeneveld, K.O.; Frankfurt Univ.

    1977-01-01

    The comparative analyses of AAS and PIXE (Proton-Induced X-ray Emission) show very good agreement in the absolute values of the concentrations of all metals analyzed. The practical detection limits are about 10 -10 g for the investigated element in both measuring processes, so that the analysis of pure air samples is possible with both methods. PIXE is particularly suitable for the analysis of aerosol samples as it is not necessary to process the filter, the samples are not destroyed, and many elements can be simultaneously analyzed within a short time (5-10 min.). Furthermore, the possibility of automatization enables an efficient treatment of meteorological problems. (orig.) [de

  18. Band-gap measurements of bulk and nanoscale hematite by soft x-ray spectroscopy

    DEFF Research Database (Denmark)

    Gilbert, B.; Frandsen, Cathrine; Maxey, E.R.

    2009-01-01

    Chemical and photochemical processes at semiconductor surfaces are highly influenced by the size of the band gap, and ability to control the band gap by particle size in nanomaterials is part of their promise. The combination of soft x-ray absorption and emission spectroscopies provides band......-gap determination in bulk and nanoscale itinerant electron semiconductors such as CdS and ZnO, but this approach has not been established for materials such as iron oxides that possess band-edge electronic structure dominated by electron correlations. We performed soft x-ray spectroscopy at the oxygen K...

  19. European X-ray spectroscopy and polarimetry payload for Spacelab

    Energy Technology Data Exchange (ETDEWEB)

    Andresen, R D; Whitcomb, G [European Space Research and Technology Centre, Noordwijk (Netherlands); Brinkman, A C [Space Research Laboratory, Utrecht, The Netherlands; Beuermann, K [Max-Planck-Institut fuer Physik und Astrophysik, Garching/Muenchen (Germany, F.R.). Inst. fuer Extraterrestrische Physik; Culhane, J L [University Coll., London (UK). Mullard Space Science Lab.; Griffiths, R [Leicester Univ. (UK); Manno, V [ESA Headquarters, Paris, France; Rocchia, R [CEA Centre d' Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)

    1976-08-01

    A group of instruments for X-ray spectroscopy and polarimetry studies of a number of cosmic X-ray sources is being designed for possible use on Spacelab. Large area Bragg spectrometers and polarimeters for photon energies above 2 keV are described. For the energy range below 2 keV, both dispersive and non-dispersive spectrometers are employed at the common focus of a nested array of paraboloids. Following a brief outline of the scientific background to the mission, the properties of the individual instruments are discussed.

  20. Resonant soft X-ray emission spectroscopy of liquids

    International Nuclear Information System (INIS)

    Guo, J.-H.; Augustsson, A.; Englund, C.-J.; Nordgren, J.

    2004-01-01

    We present now a possible way to carry out soft-x-ray fluorescence spectroscopy of liquids. The liquid cell has a window to attain compatibility with UHV conditions of the spectrometer and beamline. The synchrotron radiation enters the liquid cell through a 100nm-thick silicon nitride window and the emitted x-rays exit through the same window. This allows in particular liquid solid interfaces to be studied. Such a liquid cell has been used to study the electronic structure of a variety of systems ranging from water solutions of inorganic salts and inertial drugs to nano materials and actinide compounds in their wet conditions

  1. Raman spectroscopy and X-ray diffraction studies on celestite

    International Nuclear Information System (INIS)

    Chen Yenhua; Yu Shucheng; Huang, Eugene; Lee, P.-L.

    2010-01-01

    High-pressure Raman spectroscopy and X-ray diffraction studies of celestite (SrSO 4 ) were carried out in a diamond anvil cell at room temperature. Variation in the Raman vibrational frequency and change of lattice parameters with pressure indicate that a transformation occurs in celestite. This transformation caused an adjustment in the Sr-O polyhedra that affected the stretching-force constant of SO 4 . Moreover, compressibilities along the crystallographic axes decreased in the order a to c to b. From the compression data, the bulk modulus of the celestite was 87 GPa. Both X-ray and Raman data show that the transition in celestite is reversible.

  2. C-C bond unsaturation degree in monosubstituted ferrocenes for molecular electronics investigated by a combined near-edge x-ray absorption fine structure, x-ray photoemission spectroscopy, and density functional theory approach

    International Nuclear Information System (INIS)

    Boccia, A.; Lanzilotto, V.; Marrani, A. G.; Zanoni, R.; Stranges, S.; Alagia, M.; Fronzoni, G.; Decleva, P.

    2012-01-01

    We present the results of an experimental and theoretical investigation of monosubstituted ethyl-, vinyl-, and ethynyl-ferrocene (EtFC, VFC, and EFC) free molecules, obtained by means of synchrotron-radiation based C 1s photoabsorption (NEXAFS) and photoemission (C 1s XPS) spectroscopies, and density functional theory (DFT) calculations. Such a combined study is aimed at elucidating the role played by the C-C bond unsaturation degree of the substituent on the electronic structure of the ferrocene derivatives. Such substituents are required for molecular chemical anchoring onto relevant surfaces when ferrocenes are used for molecular electronics hybrid devices. The high resolution C 1s NEXAFS spectra exhibit distinctive features that depend on the degree of unsaturation of the hydrocarbon substituent. The theoretical approach to consider the NEXAFS spectrum made of three parts allowed to disentangle the specific contribution of the substituent group to the experimental spectrum as a function of its unsaturation degree. C 1s IEs were derived from the experimental data analysis based on the DFT calculated IE values for the different carbon atoms of the substituent and cyclopentadienyl (Cp) rings. Distinctive trends of chemical shifts were observed for the substituent carbon atoms and the substituted atom of the Cp ring along the series of ferrocenes. The calculated IE pattern was rationalized in terms of initial and final state effects influencing the IE value, with special regard to the different mechanism of electron conjugation between the Cp ring and the substituent, namely the σ/π hyperconjugation in EtFC and the π-conjugation in VFC and EFC.

  3. Rockets for Extended Source Soft X-ray Spectroscopy

    Science.gov (United States)

    McEntaffer, Randall

    The soft X-ray background surrounds our local galactic environment yet very little is known about the physical characteristics of this plasma. A high-resolution spectrum could unlock the properties of this million degree gas but the diffuse, low intensity nature of the background have made it difficult to observe, especially with a dispersive spectrograph. Previous observations have relied on X-ray detector energy resolution which produces poorly defined spectra that are poorly fit by complex plasma models. Here we propose a series of suborbital rocket flights that will begin the characterization of this elusive source through high-resolution X-ray grating spectroscopy. The rocket-based spectrograph can resolve individual emission lines over the soft X-ray band and place tight constraints on the temperature, density, abundance, ionization state and age of the plasma. These payloads will draw heavily from the heritage gained from previous rocket missions, while also benefiting from related NASA technology development programs. The Pennsylvania State University (PSU) team has a history of designing and flying spectrometer components onboard rockets while also being scientific leaders in the field of diffuse soft X-ray astronomy. The PSU program will provide hands-on training of young scientists in the techniques of instrumental and observational X-ray astronomy. The proposed rocket program will also expose these researchers to a full experiment cycle: design, fabrication, tolerance analysis, assembly, flight-qualification, calibration, integration, launch, and data analysis; using a combination of technologies suitable for adaptation to NASA's major missions. The PSU program in suborbital X-ray astronomy represents an exciting mix of compelling science, heritage, cutting-edge technology development, and training of future scientists.

  4. X-Ray and Near-Infrared Spectroscopy of Dim X-Ray Point Sources Constituting the Galactic Ridge X-Ray Emission

    Directory of Open Access Journals (Sweden)

    Kumiko Morihana

    2014-12-01

    Full Text Available We present the results of X-ray and Near-Infrared observations of the Galactic Ridge X-ray Emission (GRXE. We extracted 2,002 X-ray point sources in the Chandra Bulge Field (l =0°.113, b = 1°.424 down to ~10-14.8 ergscm-2s-1 in 2-8 keV band with the longest observation (900 ks of the GRXE. Based on X-ray brightness and hardness, we classied the X-ray point sources into three groups: A (hard, B (soft and broad spectrum, and C (soft and peaked spectrum. In order to know populations of the X-ray point sources, we carried out NIR imaging and spectroscopy observation. We identied 11% of X-ray point sources with NIR and extracted NIR spectra for some of them. Based on X-ray and NIR properties, we concluded that non-thermal sources in the group A are mostly active galactic nuclei and the thermal sources are mostly white dwarf binaries such as cataclysmic variables (CVs and Pre-CVs. We concluded that the group B and C sources are X-ray active stars in flare and quiescence, respectively.

  5. Modern Progress and Modern Problems in High Resolution X-ray Absorption from the Cold Interstellar Medium

    Science.gov (United States)

    Corrales, Lia; Li, Haochuan; Heinz, Sebastian

    2018-01-01

    With accurate cross-sections and higher signal-to-noise, X-ray spectroscopy can directly measure Milky Way gas and dust-phase metal abundances with few underlying assumptions. The X-ray energy band is sensitive to absorption by all abundant interstellar metals — carbon, oxygen, neon, silicon, magnesium, and iron — whether they are in gas or dust form. High resolution X-ray spectra from Galactic X-ray point sources can be used to directly measure metal abundances from all phases of the interstellar medium (ISM) along singular sight lines. We show our progress for measuring the depth of photoelectric absorption edges from neutral ISM metals, using all the observations of bright Galactic X-ray binaries available in the Chandra HETG archive. The cross-sections we use take into account both the absorption and scattering effects by interstellar dust grains on the iron and silicate spectral features. However, there are many open problems for reconciling X-ray absorption spectroscopy with ISM observations in other wavelengths. We will review the state of the field, lab measurements needed, and ways in which the next generation of X-ray telescopes will contribute.

  6. The effect of hydrogen absorption on the structural, electronic and magnetic properties of the C15 Friauf-Laves phase compounds CeFe2, CeRu2 and LaRu2 : an x-ray absorption spectroscopy (XAS) study

    International Nuclear Information System (INIS)

    Chaboy, J.; Garcia, J.; Marcelli, A.

    1995-08-01

    An x-ray absorption spectroscopy (XAS) investigation of the structural changes occurred upon hydriding in the Friauf-Laves phase compounds CeFe 2 , CeRu 2 and LaRu 2 compounds is presented. The analysis of the extended x-ray absorption spectroscopy (EXAFS) spectra at the L-edges of the rare-earth and at the Fe K-edge indicates that the hydrogenation process leads to the suppression of the long-range crystalline order in all the hydride derivates investigated, as well as the different influence of H 2 in both the rare earth and transition metal sublattices. The correlation between the structural and magnetic changes induced by the hydrogen in the lost matrix is discussed in terms of the modification of the electronic properties, i.e., intermediate-valence of Ce, and of the hybridization between the transition metal and rare-earth

  7. X rays and condensed matter

    International Nuclear Information System (INIS)

    Daillant, J.

    1997-01-01

    After a historical review of the discovery and study of X rays, the various interaction processes between X rays and matter are described: Thomson scattering, Compton scattering, X-photon absorption through photoelectric effect, and magnetic scattering. X ray sources such as the European Synchrotron Radiation Facility (ESRF) are described. The various X-ray applications are presented: imagery such as X tomography, X microscopy, phase contrast; X-ray photoelectron spectroscopy and X-ray absorption spectroscopy; X-ray scattering and diffraction techniques

  8. X-ray absorption study of the electronic structure of Mn-doped amorphous Si

    Energy Technology Data Exchange (ETDEWEB)

    Arenholz, Elke; Zeng, Li; Huegel, A.; Helgren, E.; Hellman, F.; Piamonteze, C.; Arenholz, E.

    2008-03-08

    The electronic structure of Mn in amorphous Si (a-Mn{sub x}Si{sub 1?x}) is studied by X-ray absorption spectroscopy at the Mn L{sub 3,2} edges for x = 0.005-0.18. Except the x = 0.005 sample, which shows a slight signature of Mn{sup 2+} atomic multiplets associated with a local Mn moment, all samples have broad and featureless L{sub 3,2} absorption peaks, corresponding to an itinerant state for all 3d electrons. The broad X-ray absorption spectra exclude the possibility of a localized 3d moment and explain the unexpectedly quenched Mn moment in this magnetically-doped amorphous semiconductor. Such a fully delocalized d state of Mn dopant in Si has not been previously suggested.

  9. Distortion of absorption-line velocity curves due to x-ray heating in x-ray binaries

    International Nuclear Information System (INIS)

    Milgrom, M.

    1976-01-01

    The effects of X-ray heating on the measured absorption line velocities, in X-ray binaries with low X-rays to optical luminosities ratio are considered. These effects may be appreciable even for such binaries where the effect of X-ray heating on the light-curve is negligible. The effects are studied qualitatively and suggest possible ways to partially eliminate the systematic errors introduced by them. The individual systems Cyg x-1 and SMC x-1 are treated and the results of numerical calculations are presented for them. For Cyg x-1 it is found that the effect is detectable during the X-ray 'high' state in all regions of the spectrum. During the 'low' state it may be important in the red region of the spectrum. The results for the case in which soft X-ray fluxes (E < or approximately .4 keV, suggested by theoretical models) are present are also given. For SMC x-1 a strong effect for Hα, Hβ, Hγ had been found. This effect may be responsible for the observed variable velocity curve. We also find for SMC x-1 that the average X-ray intensity falling on the primary must be considerably smaller than what is derived from the detected flux, or else the effect is too large. (author)

  10. Oxide ion diffusion mechanism related to Co and Fe ions in (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ using in-situ X-ray absorption spectroscopy

    Science.gov (United States)

    Itoh, Takanori; Imai, Hideto

    2018-03-01

    The time changes of the white line and pre-edge intensities of Co and Fe K-edge in (Ba0.5Sr0.5)(Co0.8Fe0.2)O3-δ (BSCF) were observed to estimate the oxide ion diffusion related to Co and Fe ions by using in - situ X-ray absorption spectroscopy (XAS) during oxidation. The 20 μm self-standing BSCF film was prepared for in - situ XAS measurements. The time changes of absorption were fitted to the exponential decay function with two terms. The longer relaxation time (τ), related to the oxide ion diffusion during the oxidation of BSCF, is dependent on temperature. The oxide ion diffusion coefficients (D) were calculated from the τ s estimated by in - situ XAS. The values of the activation energy (Ea) for D related to Co K-edge white line, Co pre-edge, and Fe pre-edge were 1.8-2.0 eV. The value of Ea for D related to Fe K-edge white line, however, was higher than other absorption values at approximately 2.3 eV. We discussed the oxide ion diffusion mechanism related to Co and Fe ions in BSCF using in - situ XAS.

  11. X-ray absorption in characterization of laser fusion targets

    International Nuclear Information System (INIS)

    Clement, X.; Coudeville, A.; Eyharts, P.; Perrine, J.P.; Rouillard, R.

    1982-11-01

    Many plastic or metal coated targets are opaque, so their thickness and thickness uniformity cannot be obtained by optical means. Therefore, we have built and tested a new system using monochromatic X-ray absorption measurements. This system is also able to perform non-destructive measurements of argon fill pressure in glass microballoons. The X-ray source is a diffraction tube with a chromium target and fine focus (0.4 x 0.8 mm 2 ). Since monochromatic calculations are involved in this method, we use electronic discrimination to isolate the chromium Kα line (5.4 keV) from the bremsstrahlung spectrum. The detectors are xenon-filled proportional counters. The system is composed of two beams (10 μm in diameter), one used as a reference and the other as the measurement arm. A PET desk computer is coupled ot the experiment. We achieved a precision better than 10% for gold layers in the range of 0.1 to 1 μm, and better than 20% for argon pressures in the range of 5 - 13 bars

  12. X-ray absorption and emission studies of diamond nanoparticles

    International Nuclear Information System (INIS)

    Van Buuren, T.; Willey, T.; Raty, J.Y.; Galli, G.; Terminello, L.J.; Bostedt, C.

    2004-01-01

    Full text: A new family of carbon nanopaticles produced in detonations, are found to have a core of diamond with a coating fullerene- like carbon. X-ray diffraction and TEM show that the nanodiamond powder is crystalline and approximately 4 nm in diameter. These nano-sized diamonds do not display the characteristic property of other group IV nanoparticles: a strong widening of the energy gap between the conduction and valence bands owing to quantum-confinement effects. For nano-sized diamond with a size distribution of 4 nm, there is no shift of the band energies relative to bulk diamond. Although the C1s core exciton feature clearly observed in the K-edge absorption edge of bulk diamond is shifted and broadening due to increased overlap of the excited electron with the core holein the small particle. Also the depth of the second gap in the nanodiamond spectra is shallower than that of bulk diamond. A feature at lower energy in the X-ray absorption spectra that is not present in the bulk samples is consistent with a fullerene like surface reconstruction. By exposing the diamond nanoparticles to an Argon /Oxygen plasma then annealing in a UHV environment we have obtained a hydrogen free surface. The nanodiamonds processed in this manner show an increase fullerene type contribution in the carbon x-ray absorption pre-edge. High spatial resolution EELS measurements of the empty states of a single nanodiamond particle acquired with a ld emission TEM also show the core of the particle is bulk diamond like where as the surface has a fullerene like structure. Standard density-functional calculations on clusters in which the diamond surface bonds are terminated with hydrogen atoms, show that the bandgap begins to increase above the bulk value only for clusters smaller than 1 nm. Surface hydrogen atoms are found to be about as close as they do in molecular hydrogen and can escape as H 2 , forcing the respective carbon atoms to rearrange. A series of such rearrangements can

  13. High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity

    International Nuclear Information System (INIS)

    Wang, Xin

    1996-12-01

    X-ray spectroscopy has long been used to elucidate electronic and structural information of molecules. One of the weaknesses of x-ray absorption is its sensitivity to all of the atoms of a particular element in a sample. Through out this thesis, a new technique for enhancing the site- and spin-selectivity of the x-ray absorption has been developed. By high resolution fluorescence detection, the chemical sensitivity of K emission spectra can be used to identify oxidation and spin states; it can also be used to facilitate site-selective X-ray Absorption Near Edge Structure (XANES) and site-selective Extended X-ray Absorption Fine Structure (EXAFS). The spin polarization in K fluorescence could be used to generate spin selective XANES or spin-polarized EXAFS, which provides a new measure of the spin density, or the nature of magnetic neighboring atoms. Finally, dramatic line-sharpening effects by the combination of absorption and emission processes allow observation of structure that is normally unobservable. All these unique characters can enormously simplify a complex x-ray spectrum. Applications of this novel technique have generated information from various transition-metal model compounds to metalloproteins. The absorption and emission spectra by high resolution fluorescence detection are interdependent. The ligand field multiplet model has been used for the analysis of Kα and Kβ emission spectra. First demonstration on different chemical states of Fe compounds has shown the applicability of site selectivity and spin polarization. Different interatomic distances of the same element in different chemical forms have been detected using site-selective EXAFS

  14. Reflections on hard X-ray photon-in/photon-out spectroscopy for electronic structure studies

    Energy Technology Data Exchange (ETDEWEB)

    Glatzel, Pieter, E-mail: glatzel@esrf.fr [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Weng, Tsu-Chien; Kvashnina, Kristina; Swarbrick, Janine; Sikora, Marcin [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Gallo, Erik [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Department of Inorganic, Physical and Materials Chemistry, INSTM Reference Center and NIS Centre of Excellence, Università di Torino, Via P. Giuria 7, I-10125 Torino (Italy); Smolentsev, Nikolay [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France); Research Center for Nanoscale Structure of Matter, Southern Federal University, str. Zorge 5, 344090 Rostov-on-Don (Russian Federation); Mori, Roberto Alonso [European Synchrotron Radiation Facility, 6 Rue Jules Horowitz, 38043 Grenoble (France)

    2013-06-15

    Highlights: ► Overview of some recent developments in hard X-ray RXES/RIXS. ► Evaluation of spectral line broadening in RXES/RIXS. ► Modelling of RXES/RIXS by ground state DFT calculations. ► Discussion on when HERFD provides a good approximation to XAS. -- Abstract: An increasing community of researchers in various fields of natural sciences is combining X-ray absorption with X-ray emission spectroscopy (XAS–XES) to study electronic structure. With the applications becoming more diverse, the objectives and the requirements in photon-in/photon-out spectroscopy are becoming broader. It is desirable to find simple experimental protocols, robust data reduction and theoretical tools that help the experimentalist to understand their data and learn about the electronic structure. This article presents a collection of considerations on non-resonant and resonant XES with the aim to guide the experimentalist to make good use of this technique.

  15. Soft X-ray spectroscopy of transition metal compounds: a theoretical perspective

    International Nuclear Information System (INIS)

    Bokarev, S.I.; Hilal, R.; Aziz, S.G.; Kühn, O.

    2017-01-01

    To date, X-ray spectroscopy has become a routine tool that can reveal highly local and element-specific information on the electronic structure of atoms in complex environments. Here, we report on the development of an efficient and versatile theoretical methodology for the treatment of soft X-ray spectra of transition metal compounds based on the multi-configurational self-consistent field electronic structure theory. A special focus is put on the L-edge photon-in/photon-out and photon-in/electron-out processes, i.e. X-ray absorption, resonant inelastic scattering, partial fluorescence yield, and photoelectron spectroscopy, all treated on the same theoretical footing. The investigated systems range from small prototypical coordination compounds and catalysts to aggregates of biomolecules.

  16. X-ray absorption anisotropy for polychromatic illumination-Crystal views from inside

    International Nuclear Information System (INIS)

    Korecki, P.; Tolkiehn, M.; Novikov, D.V.

    2009-01-01

    We review an atomic resolution imaging method based on the analysis of the fine structure in X-ray absorption anisotropy, which results from incident beam diffraction. For a polychromatic X-ray beam, due to the suppression of higher order diffraction fringes, X-ray absorption anisotropy patterns can be interpreted as distorted real-space projections of the atomic structure around absorbing atoms. A qualitative method for analysis of X-ray absorption anisotropy patterns is presented, based on modeling of X-ray patterns with ray-traced images calculated for clusters around absorbing atoms.

  17. Platform development of x-ray absorption-based temperature measurements above 100-eV on the OMEGA laser

    Science.gov (United States)

    Workman, Jonathan; Keiter, P.; Tierney, T.; Tierney, H.; Belle, K.; Magelssen, G.; Peterson, R.; Fryer, C.; Comley, A.; Taylor, M.

    2007-11-01

    Experiments were performed on the OMEGA laser system at the University of Rochester to measure radiation temperature in hohlraum-heated foams. Using x-ray absorption spectroscopy in the 3-6-keV x-ray range allows temperature determination in the range of 50-200-eV. Uranium, bismuth and gold M-shell x-ray emission were used as broadband backlighters. Backlighter absorption through heated chlorinated foam and scandium tracers were used to determine temperatures. The development of this technique in the temperature range of 100-200-eV will be used for platform development of future NIF experiments. We will present time-integrated and time-resolved measurements of x-ray emission from the backlighter materials as well as absorption measurements trough the heated tracer materials. We will also present future directions in the development of this platform.

  18. Total reflection X-ray photoelectron spectroscopy: A review

    International Nuclear Information System (INIS)

    Kawai, Jun

    2010-01-01

    Total reflection X-ray photoelectron spectroscopy (TRXPS) is reviewed and all the published papers on TRXPS until the end of 2009 are included. Special emphasis is on the historical development. Applications are also described for each report. The background reduction is the most important effect of total reflection, but interference effect, relation to inelastic mean free path, change of probing depth are also discussed.

  19. Phosphoramidates: synthesis, spectroscopy, and X-ray crystallography

    Czech Academy of Sciences Publication Activity Database

    Shariatinia, Z.; Sohrabi, M.; Yousefi, M.; Kovaľ, Tomáš; Dušek, Michal

    2012-01-01

    Roč. 23, č. 5 (2012), s. 478-485 ISSN 1042-7163 Grant - others:AV ČR(CZ) AP0701 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : phosphoramidates * X-ray diffraction * spectroscopy Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.577, year: 2012

  20. X-ray spectroscopy with normal and exotic atoms

    International Nuclear Information System (INIS)

    Qureshi, I.E.

    1995-01-01

    X-ray spectroscopy is a powerful analytical tool for elemental analysis and also for the study of nuclear properties. In recent years these has been extensive utilization of x-ray spectral analysis for the purpose of plasma diagnostics. These studies are vital for the development of controlled nuclear fusion technology. The formation of special atoms containing particles heavier than electrons is another area in which x-ray spectra give detailed knowledge of the sizes and shapes of atomic nuclei, masses and magnetic momenta of bound particles and the nature of interaction between bound particle and the nucleus. All these aspects make x-ray spectra of uniquely rich source of information on material and nuclear properties. The present article provides some glimpses of how this information is extracted. The choice of topics is biased towards nuclear physics. The presentation is not attempted to the exhaustive and is aimed at conveying the essential physical ideas without going into technical details. (author) 6 figs

  1. X-ray absorption near-edge spectroscopic study of nickel catalysts

    International Nuclear Information System (INIS)

    Soldatov, Alexander V.; Smolentsev, Grigory; Kravtsova, Antonina; Yalovega, Galina; Feiters, Martin C.; Metselaar, Gerald A.; Joly, Yves

    2006-01-01

    Ni-isocyanide and Ni-acac complexes have been studied by X-ray absorption spectroscopy. Theoretical analysis has been done using self-consistent full multiple scattering (MS) approach within both muffin-tin (MT) model of the potential and non-MT finite deference method. For the isocyanide complex, it was shown that MS theoretical spectra reproduce all structural details of the X-ray absorption near-edge structure (XANES), but also that it is important to consider the non-MT effects in the potential for a correct simulation of the shape of the pre-edge structures. The contribution of a non-constant potential in the interstitial regions is extremely important for the interpretation of the XANES of Ni(acac) 2

  2. X-ray absorption spectroscopic studies of mononuclear non-heme iron enzymes

    Energy Technology Data Exchange (ETDEWEB)

    Westre, Tami E. [Stanford Univ., CA (United States)

    1996-01-01

    Fe-K-edge X-ray absorption spectroscopy (XAS) has been used to investigate the electronic and geometric structure of the iron active site in non-heme iron enzymes. A new theoretical extended X-ray absorption fine structure (EXAFS) analysis approach, called GNXAS, has been tested on data for iron model complexes to evaluate the utility and reliability of this new technique, especially with respect to the effects of multiple-scattering. In addition, a detailed analysis of the 1s→3d pre-edge feature has been developed as a tool for investigating the oxidation state, spin state, and geometry of iron sites. Edge and EXAFS analyses have then been applied to the study of non-heme iron enzyme active sites.

  3. In-plane polarization dependence of (Bi,Pb){sub 2}Sr{sub 2}CaCu{sub 2}O{sub 8+δ} single crystals studied by X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Ghafari, A., E-mail: ghafari@physik.hu-berlin.de [Institute of Physics, Humboldt University of Berlin, Newtonstr., 15, D-12489 Berlin (Germany); Elettra Sincrotrone Trieste, Strada Statale 14 km 163.5, I-34149 Trieste (Italy); Ariffin, A.K. [Institute of Physics, Humboldt University of Berlin, Newtonstr., 15, D-12489 Berlin (Germany); Department of Physics, Universiti Pendidikan Sultan Idris, 35900 Tanjong Malim (Malaysia); Janowitz, C., E-mail: christoph.janowitz@physik.hu-berlin.de [Institute of Physics, Humboldt University of Berlin, Newtonstr., 15, D-12489 Berlin (Germany); Dwelk, H.; Krapf, A.; Manzke, R. [Institute of Physics, Humboldt University of Berlin, Newtonstr., 15, D-12489 Berlin (Germany)

    2014-06-15

    The effects of in-plane polarization change on the determination of the hole density of weakly under-doped (Bi, Pb)-2212 single crystals has been studied by x-ray absorption spectroscopy (XAS). The XAS signal at the CuL{sub 3} edge (925–940 eV) and O K edge (525 eV to 539 eV) were recorded under continuous rotation of the CuO{sub 2} plane from 0° to 180° with a minimum increment of 1.8°, yielding experimentally an in-plane polarization dependence for the absorption signals at the respective threshold. From that the in-plane angular dependence of the hole density (n{sub H}(φ)) could be determined. Fermi's golden rule was then used for the evaluation of the in-plane polarization dependence showing the expected polarization independence in disaccord to the experimental observations. Possible scenarios to solve this issue are discussed. Our results propose that polarization dependence could be due to inhomogeneous distribution of holes in the CuO{sub 2} planes which is also supported by models. Second, the role of out of plane orbitals has to be taken into account for interpretation.

  4. Valence states and occupation sites in (Fe,Mn){sub 3}O{sub 4} spinel oxides investigated by soft x-ray absorption spectroscopy and magnetic circular dichroism

    Energy Technology Data Exchange (ETDEWEB)

    Lee, H J; Kim, G; Kim, D H; Kang, J-S [Department of Physics, Catholic University of Korea (CUK), Bucheon 420-743 (Korea, Republic of); Zhang, C L; Cheong, S-W [Rutgers Center for Emergent Materials and Department of Physics, Rutgers University, Piscataway, NJ 08854 (United States); Shim, J H; Lee, Soonchil [Department of Physics, KAIST, Daejeon 305-701 (Korea, Republic of); Lee, Hangil; Kim, J-Y [Pohang Accelerator Laboratory (PAL), POSTECH, Pohang 790-784 (Korea, Republic of); Kim, B H; Min, B I [Department of Physics, POSTECH, Pohang 790-784 (Korea, Republic of)], E-mail: kangjs@catholic.ac.kr

    2008-07-23

    The electronic structures of (Fe,Mn){sub 3}O{sub 4} spinel oxides have been investigated by employing soft-x-ray absorption spectroscopy (XAS) and soft x-ray magnetic circular dichroism (XMCD). We have determined the valence states as well as the occupation sites of Mn and Fe ions in Fe{sub 0.9}Mn{sub 2.1}O{sub 4} and MnFe{sub 2}O{sub 4}. Fe{sub 0.9}Mn{sub 2.1}O{sub 4} is found to be close to the inverse spinel (the inversion parameter y{approx}0.85), while MnFe{sub 2}O{sub 4} is close to the normal spinel (y{approx}0.2). In Fe{sub 0.9}Mn{sub 2.1}O{sub 4}, Fe ions are mainly trivalent and the majority of Fe{sup 3+} ions occupy the octahedral B sites, while Mn ions are mixed-valent with approximately 45% Mn{sub A}{sup 2+} at the tetrahedral A sites and 55% Mn{sub B}{sup 3+} ions at the octahedral B sites. In MnFe{sub 2}O{sub 4}, Mn ions are mainly divalent and the majority of Mn{sup 2+} ions occupy the tetrahedral A sites, while Fe ions are mainly trivalent and the majority of Fe{sup 3+} ions occupy the octahedral B sites.

  5. Design of solar cell materials via soft X-ray spectroscopy

    DEFF Research Database (Denmark)

    Himpsel, F.J.; Cook, P.L.; de la Torre, G.

    2013-01-01

    This overview illustrates how spectroscopy with soft X-rays can assist the development of new materials and new designs for solar cells. The starting point is the general layout of a solar cell, which consists of a light absorber sandwiched between an electron donor and an electron acceptor....... There are four relevant energy levels that can be measured with a combination of X-ray absorption spectroscopy and photoelectron spectroscopy, as illustrated for an organic dye as absorber attached to a p-doped diamond film as donor. Systematic measurements of organometallic dyes (phthalocyanines and porphyrins......) as a function of the metal atom are presented for the metal 2p and N 1s absorption edges. In combination with density functional theory one can discern trends that are useful for tailoring absorber molecules. A customized porphyrin molecule is investigated that combines an absorber with a donor and a linker...

  6. Characterization of the electronic structure of C50Cl10 by means of soft x-ray spectroscopies

    International Nuclear Information System (INIS)

    Brena, Barbara; Luo Yi

    2005-01-01

    The electronic structure of the last synthesized fullerene molecule, the C 50 Cl 10 , has been characterized by theoretical simulation of x-ray photoelectron spectroscopy, ultraviolet photoelectron spectroscopy, and near-edge x-ray-absorption fine structure. All the calculations were performed at the gradient-corrected and hybrid density-functional theory levels. The combination of these techniques provides detailed information about the valence band and the unoccupied molecular orbitals, as well as about the carbon core orbitals

  7. Weak hard X-ray emission from broad absorption line quasars: evidence for intrinsic X-ray weakness

    International Nuclear Information System (INIS)

    Luo, B.; Brandt, W. N.; Scott, A. E.; Alexander, D. M.; Gandhi, P.; Stern, D.; Teng, S. H.; Arévalo, P.; Bauer, F. E.; Boggs, S. E.; Craig, W. W.; Christensen, F. E.; Comastri, A.; Farrah, D.; Hailey, C. J.; Harrison, F. A.; Koss, M.; Ogle, P.; Puccetti, S.; Saez, C.

    2014-01-01

    We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148-1.223, are among the optically brightest and most luminous BAL quasars known at z < 1.3. However, their rest-frame ≈2 keV luminosities are 14 to >330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a Chandra stacking analysis of a sample of high-redshift BAL quasars, and a NuSTAR spectral analysis of the local BAL quasar Mrk 231 have already suggested the existence of intrinsically X-ray weak BAL quasars, i.e., quasars not emitting X-rays at the level expected from their optical/UV emission. The aim of the current program is to extend the search for such extraordinary objects. Three of the six new targets are weakly detected by NuSTAR with ≲ 45 counts in the 3-24 keV band, and the other three are not detected. The hard X-ray (8-24 keV) weakness observed by NuSTAR requires Compton-thick absorption if these objects have nominal underlying X-ray emission. However, a soft stacked effective photon index (Γ eff ≈ 1.8) for this sample disfavors Compton-thick absorption in general. The uniform hard X-ray weakness observed by NuSTAR for this and the pilot samples selected with <10 keV weakness also suggests that the X-ray weakness is intrinsic in at least some of the targets. We conclude that the NuSTAR observations have likely discovered a significant population (≳ 33%) of intrinsically X-ray weak objects among the BAL quasars with significantly weak <10 keV emission. We suggest that intrinsically X-ray weak quasars might be preferentially observed as BAL quasars.

  8. Advances in X-ray spectroscopy contributions in honour of professor Y. Cauchois

    CERN Document Server

    Bonnelle, C

    1982-01-01

    Advances in X-Ray Spectroscopy covers topics relevant to the advancement of X-ray spectroscopy technology. The book is a collection of papers written by specialists in X-ray spectroscopy and pays tribute to the scientific work of Prof. Yvette Cauchois. The text is organized into four parts. Part I covers the analysis of X-ray transitions between atomic levels and relativistic theories of X-ray emission satellites and electron BremsStrahlung. Part II reviews the means provided by X-ray spectroscopy for the determination of the electronic structure of solids, while Part III discusses methods of

  9. Energy dispersive X-ray spectroscopy with microcalorimeters

    International Nuclear Information System (INIS)

    Hollerith, C.; Wernicke, D.; Buehler, M.; Feilitzsch, F. von; Huber, M.; Hoehne, J.; Hertrich, T.; Jochum, J.; Phelan, K.; Stark, M.; Simmnacher, B.; Weiland, W.; Westphal, W.

    2004-01-01

    Shrinking feature sizes in semiconductor device production as well as the use of new materials demand innovation in device technology and material analysis. X-ray spectrometers based on superconducting sensor technology are currently closing the gap between fast energy dispersive spectroscopy (EDS) and high-resolution wavelength dispersive spectroscopy (WDS). This work reports on the successful integration of iridium/gold transition edge sensors in the first industrially used microcalorimeter EDS. The POLARIS microcalorimeter system is installed at the failure analysis lab FA5 at Infineon Technologies AG in Neuperlach (Munich) and is used in routine analysis

  10. Probing deeper by hard x-ray photoelectron spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Risterucci, P.; Renault, O., E-mail: olivier.renault@cea.fr; Martinez, E.; Delaye, V. [CEA, LETI, MINATEC Campus, 38054 Grenoble Cedex 09 (France); Detlefs, B. [CEA, LETI, MINATEC Campus, 38054 Grenoble Cedex 09 (France); European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Zegenhagen, J. [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Gaumer, C. [STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles (France); Grenet, G. [Institut des Nanotechnologies de Lyon (INL), UMR CNRS 5270, Ecole Centrale de Lyon, 36, avenue Guy de Collongue 69 134 Ecully Cedex (France); Tougaard, S. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)

    2014-02-03

    We report an hard x-ray photoelectron spectroscopy method combining high excitation energy (15 keV) and improved modelling of the core-level energy loss features. It provides depth distribution of deeply buried layers with very high sensitivity. We show that a conventional approach relying on intensities of the core-level peaks is unreliable due to intense plasmon losses. We reliably determine the depth distribution of 1 ML La in a high-κ/metal gate stack capped with 50 nm a-Si. The method extends the sensitivity of photoelectron spectroscopy to depths beyond 50 nm.

  11. Effects of Cations on the Hydrogen Bond Network of Liquid Water: New Results from X-ray Absorption Spectroscopy of Liquid Microjets

    International Nuclear Information System (INIS)

    Cappa, Christopher D.; Smith, Jared D.; Messer, Benjamin M.; Cohen, Ronald C.; Saykally, Richard J.

    2005-01-01

    The oxygen K-edge absorption spectra (XAS) of aqueous chloride solutions are measured for Li + , Na + , K + , NH + , C(NH2) 3 + , Mg 2+ and Ca 2+ and 4 M cation concentrations. Density functional theory calculation have indicated that the ion-specific spectral variations arise from direct electronic perturbation of the unoccupied orbitals due to the presence of the ions, as a result of differences in charge transfer from the water molecules onto the divalent cations

  12. Structural studies using X-ray absorption and scattering techniques

    International Nuclear Information System (INIS)

    Ericson, Agneta.

    1989-01-01

    The thesis presents extended X-ray absorption fine structure, EXAFS, and large angle X-ray scattering, LAXS, techniques; instrumentation, data collection and reduction, and applications. These techniques have been used to determine the structures of magnesium halides and organomagnesium halides in diethyl ether and tetrahydrofuran solution. The iodides were used for the LAXS measurements and Br K edge EXAFS data were collected for the corresponding bromides. Two different complexes are present in the diethyl ether solution of magnesium iodide; a polymeric chain-type structure where magnesium is tetrahedrally coordinated, as well as dimeric complex with octahedrally coordinated magnesium. Solvated MgI + is the dominating species in tetrahydrofuran solution. The organomagnesium halides are present in diethyl ether solution as both solvated monomeric and dimeric complexes. Magnesium coordinates a halide ion, an alkyl or aryl group and four solvent molecules octahedrally in the monomeric complex. In the dimeric complex magnesium is octahedrally coordinated by two bridging halide ions, an alkyl or aryl group and three solvent molecules. The distribution of monomeric and dimeric complexes in various solutions are given by a dimerisation constant, K dl . The results indicate that the Schlenk equilibrium is present in these solutions, however, in an extended form. In diethyl ether solution, where MgX 2 does not dissociate, no MgX 2 complex and thereby no Schlenk equilibrium has been observed. In tetrahydrofuran solution MgI 2 has dissociated into mainly MgI + and I - . This indicates that the concentration of MgI 2 is low and that the Schlenk equilibrium should be expanded even further to include the dissociation equilibrium of the magnesium halide. In the thesis Fe K edge EXAFS data collected for the semireduced form of protein A of methane monooxygenase from Methylococcus capsulatus, are also presented. (139 refs.)

  13. Hard X-ray emission spectroscopy with pink beam

    Energy Technology Data Exchange (ETDEWEB)

    Kvashnina, Kristina O.; Rossberg, Andre; Exner, Joerg; Scheinost, Andreas C. [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Molecular Structures

    2017-06-01

    Valence-band X-ray emission spectroscopy (XES) with a ''pink beam'', i.e. a beam with large energy bandwidth produced by a double-multilayer monochromator, is introduced here to overcome the weak count rate of monochromatic beams produced by conventional double-crystal monochromators. Our results demonstrate that - in spite of the large bandwidth in the order of 100 eV - the high spectral resolution of the Johann-type spectrometer is maintained, while the two orders of magnitude higher flux greatly reduces the required counting time. The short working distance Johann-type X-ray emission spectrometer and multilayer monochromator is available at ROBL.

  14. High resolution X-ray spectroscopy from the Einstein Observatory

    International Nuclear Information System (INIS)

    Winkler, P.F.; Canizares, C.R.; Clark, G.W.; Markert, T.H.; Berg, C.; Jernigan, J.G.; Schattenberg, M.L.; Massachusetts Inst. of Tech., Cambridge

    1980-01-01

    This paper is devoted to a discussion of some results which we have recently obtained from the fourth of the principal intruments on board the Einstein Observatory: M.I.T.'s Focal Plane Crystal Spectrometer (FPCS). We shall begin whith a few general remarks about X-ray spectroscopy, followed by a brief description of the FPCS instrument. The results we present here deal primarily with supernova remnants (SNRs): Puppis A and Cas A in the Galaxy, and N132D and N63A in the Large Magellanic Cloud. In addition we shall briefly discuss a member of the other class of thermal X-ray source under discussion at present; namely, to report our detection of oxygen emission from the vicinity of M87 in the Virgo Cluster. (orig.)

  15. X-ray spectroscopy of laser imploded targets

    International Nuclear Information System (INIS)

    Yaakobi, B.; Skupsky, S.; McCrory, R.L.; Hooper, C.F.; Deckman, H.; Bourke, P.; Soures, J.M.

    1981-01-01

    X-ray spectroscopy provides a variety of means for studying the interaction of lasers with plasmas, in particular the interaction with imploding targets in inertial confinement fusion. A typical fusion target is composed of materials other than the thermonuclear fuel which play a variety of roles (tamping, shielding, thermal isolation, etc.). These structural elements emit characteristic X-ray lines and continua, and through their spectral and spatial distributions can yield very valuable information on the interaction and implosion dynamics. Examples are the study of heat conductivity, the mixing of different target layers, and the determination of temperature and density at the compressed target core. Results will be shown for electron densities Nsub(e) approximately equal to 10 24 cm -3 and temperatures T approximately equal to 1 keV measured during compression of argon-filled targets with a six-beam laser of peak power 2 TW. (author)

  16. AXSIS: Exploring the frontiers in attosecond X-ray science, imaging and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Kärtner, F.X., E-mail: franz.kaertner@cfel.de [Center for Free-Electron Laser Science, Hamburg (Germany); Institute for Experimental Physics, University of Hamburg, Hamburg (Germany); The Hamburg Center for Ultrafast Imaging, Hamburg (Germany); DESY, Hamburg (Germany); Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA (United States); Ahr, F. [Center for Free-Electron Laser Science, Hamburg (Germany); Institute for Experimental Physics, University of Hamburg, Hamburg (Germany); DESY, Hamburg (Germany); Max Planck Institute for the Structure and Dynamics of Matter, Hamburg (Germany); Calendron, A.-L. [Center for Free-Electron Laser Science, Hamburg (Germany); Institute for Experimental Physics, University of Hamburg, Hamburg (Germany); The Hamburg Center for Ultrafast Imaging, Hamburg (Germany); DESY, Hamburg (Germany); Çankaya, H. [Center for Free-Electron Laser Science, Hamburg (Germany); The Hamburg Center for Ultrafast Imaging, Hamburg (Germany); DESY, Hamburg (Germany); Carbajo, S. [Center for Free-Electron Laser Science, Hamburg (Germany); Institute for Experimental Physics, University of Hamburg, Hamburg (Germany); DESY, Hamburg (Germany); Chang, G.; Cirmi, G. [Center for Free-Electron Laser Science, Hamburg (Germany); The Hamburg Center for Ultrafast Imaging, Hamburg (Germany); DESY, Hamburg (Germany); Dörner, K. [Center for Free-Electron Laser Science, Hamburg (Germany); DESY, Hamburg (Germany); Dorda, U. [DESY, Hamburg (Germany); Fallahi, A. [Center for Free-Electron Laser Science, Hamburg (Germany); DESY, Hamburg (Germany); Hartin, A. [Center for Free-Electron Laser Science, Hamburg (Germany); Institute for Experimental Physics, University of Hamburg, Hamburg (Germany); DESY, Hamburg (Germany); Hemmer, M. [Center for Free-Electron Laser Science, Hamburg (Germany); DESY, Hamburg (Germany); and others

    2016-09-01

    X-ray crystallography is one of the main methods to determine atomic-resolution 3D images of the whole spectrum of molecules ranging from small inorganic clusters to large protein complexes consisting of hundred-thousands of atoms that constitute the macromolecular machinery of life. Life is not static, and unravelling the structure and dynamics of the most important reactions in chemistry and biology is essential to uncover their mechanism. Many of these reactions, including photosynthesis which drives our biosphere, are light induced and occur on ultrafast timescales. These have been studied with high time resolution primarily by optical spectroscopy, enabled by ultrafast laser technology, but they reduce the vast complexity of the process to a few reaction coordinates. In the AXSIS project at CFEL in Hamburg, funded by the European Research Council, we develop the new method of attosecond serial X-ray crystallography and spectroscopy, to give a full description of ultrafast processes atomically resolved in real space and on the electronic energy landscape, from co-measurement of X-ray and optical spectra, and X-ray diffraction. This technique will revolutionize our understanding of structure and function at the atomic and molecular level and thereby unravel fundamental processes in chemistry and biology like energy conversion processes. For that purpose, we develop a compact, fully coherent, THz-driven attosecond X-ray source based on coherent inverse Compton scattering off a free-electron crystal, to outrun radiation damage effects due to the necessary high X-ray irradiance required to acquire diffraction signals. This highly synergistic project starts from a completely clean slate rather than conforming to the specifications of a large free-electron laser (FEL) user facility, to optimize the entire instrumentation towards fundamental measurements of the mechanism of light absorption and excitation energy transfer. A multidisciplinary team formed by laser

  17. High energy X-ray phase and dark-field imaging using a random absorption mask.

    Science.gov (United States)

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-07-28

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science.

  18. A Comprehensive X-Ray Absorption Model for Atomic Oxygen

    Science.gov (United States)

    Gorczyca, T. W.; Bautista, M. A.; Hasoglu, M. F.; Garcia, J.; Gatuzz, E.; Kaastra, J. S.; Kallman, T. R.; Manson, S. T.; Mendoza, C.; Raassen, A. J. J.; hide

    2013-01-01

    An analytical formula is developed to accurately represent the photoabsorption cross section of atomic Oxygen for all energies of interest in X-ray spectral modeling. In the vicinity of the K edge, a Rydberg series expression is used to fit R-matrix results, including important orbital relaxation effects, that accurately predict the absorption oscillator strengths below threshold and merge consistently and continuously to the above-threshold cross section. Further, minor adjustments are made to the threshold energies in order to reliably align the atomic Rydberg resonances after consideration of both experimental and observed line positions. At energies far below or above the K-edge region, the formulation is based on both outer- and inner-shell direct photoionization, including significant shake-up and shake-off processes that result in photoionization-excitation and double-photoionization contributions to the total cross section. The ultimate purpose for developing a definitive model for oxygen absorption is to resolve standing discrepancies between the astronomically observed and laboratory-measured line positions, and between the inferred atomic and molecular oxygen abundances in the interstellar medium from XSTAR and SPEX spectral models.

  19. Element-resolved x-ray ferrimagnetic and ferromagnetic resonance spectroscopy

    International Nuclear Information System (INIS)

    Boero, G; Mouaziz, S; Rusponi, S; Bencok, P; Nolting, F; Stepanow, S; Gambardella, P

    2008-01-01

    We report on the measurement of element-specific magnetic resonance spectra at gigahertz frequencies using x-ray magnetic circular dichroism (XMCD). We investigate the ferrimagnetic precession of Gd and Fe ions in Gd-substituted yttrium iron garnet, showing that the resonant field and linewidth of Gd precisely coincide with Fe up to the nonlinear regime of parametric excitations. The opposite sign of the Gd x-ray magnetic resonance signal with respect to Fe is consistent with dynamic antiferromagnetic alignment of the two ionic species. Further, we investigate a bilayer metal film, Ni 80 Fe 20 (5 nm)/Ni(50 nm), where the coupled resonance modes of Ni and Ni 80 Fe 20 are separately resolved, revealing shifts in the resonance fields of individual layers but no mutual driving effects. Energy-dependent dynamic XMCD measurements are introduced, combining x-ray absorption and magnetic resonance spectroscopies

  20. Simulating Ru L 3 -Edge X-ray Absorption Spectroscopy with Time-Dependent Density Functional Theory: Model Complexes and Electron Localization in Mixed-Valence Metal Dimers

    Energy Technology Data Exchange (ETDEWEB)

    Van Kuiken, Benjamin E.; Valiev, Marat; Daifuku, Stephanie L.; Bannan, Caitlin; Strader, Matthew L.; Cho, Hana; Huse, Nils; Schoenlein, Robert W.; Govind, Niranjan; Khalil, Munira

    2013-05-30

    Ruthenium L3-edge X-ray absorption (XA) spectroscopy probes unoccupied 4d orbitals of the metal atom and is increasingly being used to investigate the local electronic structure in ground and excited electronic states of Ru complexes. The simultaneous development of computational tools for simulating Ru L3-edge spectra is crucial for interpreting the spectral features at a molecular level. This study demonstrates that time-dependent density functional theory (TDDFT) is a viable and predictive tool for simulating ruthenium L3-edge XA spectroscopy. We systematically investigate the effects of exchange correlation functional and implicit and explicit solvent interactions on a series of RuII and RuIII complexes in their ground and electronic excited states. The TDDFT simulations reproduce all of the experimentally observed features in Ru L3-edge XA spectra within the experimental resolution (0.4 eV). Our simulations identify ligand-specific charge transfer features in complicated Ru L3-edge spectra of [Ru(CN)6]4- and RuII polypyridyl complexes illustrating the advantage of using TDDFT in complex systems. We conclude that the B3LYP functional most accurately predicts the transition energies of charge transfer features in these systems. We use our TDDFT approach to simulate experimental Ru L3-edge XA spectra of transition metal mixed-valence dimers of the form [(NC)5MII-CN-RuIII(NH3)5] (where M = Fe or Ru) dissolved in water. Our study determines the spectral signatures of electron delocalization in Ru L3-edge XA spectra. We find that the inclusion of explicit solvent molecules is necessary for reproducing the spectral features and the experimentally determined valencies in these mixed-valence complexes. This study validates the use of TDDFT for simulating Ru 2p excitations using popular quantum chemistry codes and providing a powerful interpretive tool for equilibrium and ultrafast Ru L3-edge XA spectroscopy.

  1. Stabilization of high-temperature antimony oxide with molybdenum incorporation. Structure of Mo-doped Sb2O4 by powder neutron diffraction and extended X-ray absorption fine structure spectroscopy

    International Nuclear Information System (INIS)

    Teller, R.G.; Antonio, M.R.; Brazdil, J.F.; Mehicic, M.; Grasselli, R.K.

    1985-01-01

    It has been discovered that the presence of MoO 3 lowers the α-β transition in Sb 2 O 4 from 935 to 850 0 C with concurrent dissolution of Mo in the high-temperature (β) form. The structure of Mo-doped β-Sb 2 O 4 has been investigated by powder neutron diffraction, extended X-ray absorption fine structure (EXAFS) and Raman spectroscopies, and scanning-electron microscopy (SEM). Cell parameters: a = 12.0571 (12) A, b = 4.8335 (1) A, c = 5.3838 (6) A, β = 105.579 (5) 0 , monoclinic, space group C2/c, Z = 4. Combining the results of these techniques leads to the hypothesis that Mo is located interstitially within channels of electron density in the Sb 2 O 4 structure with concurrent vacancy of two Sb/sup III/ atoms. There is no apparent oxygen deficiency in the resulting structure. 25 references, 6 figures, 3 tables

  2. Probing the Influence of the Conjugated Structure and Halogen Atoms of Poly-Iron-Phthalocyanine on the Oxygen Reduction Reaction by X-ray Absorption Spectroscopy and Density Functional Theory

    International Nuclear Information System (INIS)

    Peng, Yingxiang; Cui, Lufang; Yang, Shifeng; Fu, Jingjing; Zheng, Lirong; Liao, Yi; Li, Kai; Zuo, Xia; Xia, Dingguo

    2015-01-01

    Metal-phthalocyanine (MPc) macrocyclic catalysts have been perceived as promising alternatives to Pt and Pt-based catalysts for the oxygen reduction reaction (ORR). However, the effect of different MPc molecular structures on the ORR has rarely been reported in depth. Herein, iron-phthalocyanine polymers (poly-FePcs) and multi-walled carbon nanotubes (MWCNTs) composites with different structures were synthesized using microwave method. The relationship between their molecular structure and electrocatalytic activity was fully revealed by density functional theory (DFT) and X-ray fine absorption spectroscopy (XAFS). DFT calculations revealed that the introduction of halogen atoms can increase the ion potential (IP) and the dioxo-binding energy () of the poly-FePcs. Meanwhile, their conjugated structure not only facilitates electronic transmission, but also significantly increases . XAFS analysis indicated that the poly-FePc/MWCNTs composites had a square planar structure and a smaller of phthalocyanine ring (Fe-N 4 structure) skeleton structure radius when a larger conjugated structure or introduced halogen atoms was present. The experimental results suggest that the these changes in properties arising from the different structures of the MPc macrocyclic compounds led to a huge effect on their ORR electrochemical activities, and provide a guide to obtaining promising electrochemical catalysts

  3. Electrochemical Dissolution of Iridium and Iridium Oxide Particles in Acidic Media: Transmission Electron Microscopy, Electrochemical Flow Cell Coupled to Inductively Coupled Plasma Mass Spectrometry, and X-ray Absorption Spectroscopy Study.

    Science.gov (United States)

    Jovanovič, Primož; Hodnik, Nejc; Ruiz-Zepeda, Francisco; Arčon, Iztok; Jozinović, Barbara; Zorko, Milena; Bele, Marjan; Šala, Martin; Šelih, Vid Simon; Hočevar, Samo; Gaberšček, Miran

    2017-09-13

    Iridium-based particles, regarded as the most promising proton exchange membrane electrolyzer electrocatalysts, were investigated by transmission electron microscopy and by coupling of an electrochemical flow cell (EFC) with online inductively coupled plasma mass spectrometry. Additionally, studies using a thin-film rotating disc electrode, identical location transmission and scanning electron microscopy, as well as X-ray absorption spectroscopy have been performed. Extremely sensitive online time-and potential-resolved electrochemical dissolution profiles revealed that Ir particles dissolve well below oxygen evolution reaction (OER) potentials, presumably induced by Ir surface oxidation and reduction processes, also referred to as transient dissolution. Overall, thermally prepared rutile-type IrO 2 particles are substantially more stable and less active in comparison to as-prepared metallic and electrochemically pretreated (E-Ir) analogues. Interestingly, under OER-relevant conditions, E-Ir particles exhibit superior stability and activity owing to the altered corrosion mechanism, where the formation of unstable Ir(>IV) species is hindered. Due to the enhanced and lasting OER performance, electrochemically pre-oxidized E-Ir particles may be considered as the electrocatalyst of choice for an improved low-temperature electrochemical hydrogen production device, namely a proton exchange membrane electrolyzer.

  4. X-ray absorption spectroscopy on phosphoric-salt pellets. Determination of the geometric and electronic structure of metal-oxide doped sodium-phosphate glasses; Roentgenabsorptionsspektroskopie an Phosphorsalzperlen. Bestimmung der geometrischen und elektronischen Struktur von metalloxid-dotierten Natriumphosphatglaesern

    Energy Technology Data Exchange (ETDEWEB)

    Brendebach, B.

    2004-02-01

    Sodium metaphosphate glasses doped with transition metal oxides show characteristic colors. X-ray absorption spectroscopy (XAS) investigations provide information whether the coloration stems from different electronic transitions or changes in the geometrical structure of the glasses. Even though the violet color of MnO{sub y}-doped glasses is considered as an evidence for Mn{sup 3+}-ions, Mn K-XAS reveals that the majority of the manganese ions are in the oxidation state +II and have a mixed coordination of four and six oxygen atoms, respectively. The oxygen coordination around the nickel ions in NiO-doped glasses with different metall oxide concentrations is always six. The change of color from citreous to auburn with increasing nickel oxide content is attributed to a systematic change in the bonding characteristic from mainly ionic-like to a small but significant contribution of covalent-like bonding. Analysis of higher coordination shells provides no indication of the formation of metal oxide clusters. (orig.)

  5. Extended X-ray absorption fine structure and X-ray diffraction studies on supported Ni catalysts

    International Nuclear Information System (INIS)

    Aldea, N.; Marginean, P.; Yaning, Xie; Tiandou, Hu; Tao, Liu; Wu, Zhongua; ZhenYa, Dai

    1999-01-01

    In the first part of this paper, we present a study based on EXAFS spectroscopy. This method can yield structural information about the local environment around a specific atomic constituent in the amorphous materials, the location and chemical state of any catalytic atom on any support or point defect structures, in alloys and composites. EXAFS is a specific technique of the scattering of X-ray on materials. The present study is aimed toward elucidation of the local structure of Ni atoms and their interaction with oxide support. The second goal of the paper consists in X-ray diffraction on the same samples. X-ray diffraction method that is capable to determine average particle size, microstrains, probability of faults as well as particle size distribution function of supported Ni catalysts is presented. The method is based on the Fourier analysis of a single X-Ray diffraction profile. The results obtained on supported nickel catalysts, which are used in H/D isotopic exchange reactions are reported. The global structure is obtained with a new fitting method based on the Generalised Fermi Function facilities for approximation and Fourier transform of the experimental X-Ray line profiles. Both types of measurements were performed on Beijing Synchrotron Radiation Facilities (BSRF). (authors)

  6. Directional fine structure in absorption of white x rays: A tomographic interpretation

    International Nuclear Information System (INIS)

    Korecki, P.; Szymonski, M.; Tolkiehn, M.; Novikov, D. V.; Materlik, G.

    2006-01-01

    We discuss directional fine structure in absorption of white x rays for tomographic imaging of crystal structure at the atomic level. The interference between a direct x-ray beam and the secondary waves coherently scattered inside a specimen modifies the total wave field at the position of the absorbing atoms. For a white x-ray beam, the wave field variations cancel out by energy integration for all directions, except for the near forward scattering components, coinciding with the incident beam. Therefore, two-dimensional patterns of the angular-dependent fine structure in absorption of white x rays can be interpreted as real-space projections of atomic structure. In this work, we present a theory describing the directional fine structure in white x-ray absorption and a tomographic approach for crystal structure retrieval developed on its basis. The tomographic algorithm is applied to the experimental x-ray absorption data recorded for GaP crystals

  7. LNLS soft x-ray spectroscopy (SXS) beamline

    International Nuclear Information System (INIS)

    Tolentino, Helio; Rocha, Milton C.; Tamura, Edilson; Cezar, Julio C.; Vicentin, Flavio C.; Giles, Carlos; Compagnon-Cailhol, Valerie; Abbate, Miguel; Cruz, Daniela Z.N.; Mocellin, Alexandra

    1996-01-01

    The Soft X-ray Spectroscopy beamline will be dedicated to the study of structural, electronic and magnetic properties of materials by using photoabsorption and photoemission techniques, X-ray dischroism will be used to study magnetism of transition metals and rare earths compounds. This beamline is one of the first seven beamlines which were decided to start operation along with the storage ring. Part of the beamline - mostly importations - has been granted by fundings from the state of Sao Paulo (Fapesp). The electron energy analyser came through EEC from a cooperation with a French group at LURE. All components of the beamline are either constructed or bougth and being mounted at the storage ring. The monochromator has already been commissioned under UHV, attaining the specification of 5x10 -9 Torr. To cover the whole energy range, from 800 eV up to 4000 eV, many crystals have been bought, cut and tested. The mirror has been specified in order to focus the source in both directions. Simulations using the Shadow code (source simulation and ray tracing technique) were performed in order to optimize the performance of the optics. We expert to focus 10 mrad down to a spot of 3.0x1.5 mm 2 . The mirror chamber has already been constructed and commissioned under UHV conditions (pressure -9 Torr). The mechanics (mechanical feedthroughs, stability, etc..) has been tested using an X-ray source and has been approved. The experimental chamber has already been used for photoemission experiments using a conventional AL/Mg X-ray source. Many results have been obtained and two master thesis have been performed using this set-up. (author)

  8. Metallic magnetic calorimeters for high resolution X-ray spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Krantz, M.; Hengstler, D.; Geist, J.; Schoetz, C.; Hassel, K.; Hendricks, S.; Keller, M.; Kempf, S.; Gastaldo, L.; Fleischmann, A.; Enss, C. [Heidelberg Univ. (Germany). KIP

    2015-07-01

    We develop microfabricated, energy dispersive particle detector arrays based on metallic magnetic calorimeters (MMCs) for high resolution X-ray spectroscopy to challenge bound-state QED calculations. Our MMCs are operated at about T=30 mK and use a paramagnetic temperature sensor, read-out by a SQUID, to measure the energy deposited by single X-ray photons. We discuss the physics of MMCs, the detector performance and the cryogenic setups for two different detector arrays. We present their microfabrication layouts with focus on challenges like the heatsinking of each pixel of the detector and the overhanging absorbers. The maXs-20 detector is a linear 1x8-pixel array with excellent linearity in its designated energy range up to 20 keV and unsurpassed energy resolution of 1.6 eV for 6 keV x-rays. MaXs-20 operated in a highly portable pulse tube cooled ADR setup has already been used at the EBIT facilities of the MPI-K for new reference measurements of V-like and Ti-like tungsten. The maXs-30 detector currently in development is a 8x8-pixel 2d-array with an active detection area of 16 mm{sup 2} and is designed to detect X-rays up to 50 keV with a designated energy resolution below 5 eV. MaXs-30 will be operated in a cryogen free 3He/4He-dilution refrigerator at the tip of a 40 cm long cold finger at T=20 mK.

  9. Usage of X-ray absorption spectroscopy and extractive fractionation in studies of the Cu (II and Zn (II ions in soils

    Directory of Open Access Journals (Sweden)

    Dina Nevidomskaya

    2014-12-01

    Full Text Available XANES spectroscopy is an effective method for the study of bonds between metals and soil components. The study of structural organization in different soil samples and soil phases saturated with Cu2+ and Zn2+ ions by using XANES allowed determining the mechanism of their interaction with soil phases and all the chemical bindings taken place in the course of this process. Changes in the structure of the metal ion, in particular breakdown of the symmetry of electron orbits of atoms, take place due to interaction with soil components. Application of this method demonstrated that the state of copper and zinc introduced in chernozem as oxides did not change after one year of incubation. Copper is absorbed after being introduced as soluble salts, and copper ions are incorporated in the octahedral and tetrahedral sites of minerals and bonded with humic materials at the expense of covalent bond and the formation of coordination humate copper complexes. Zinc included into octahedric structures of layered minerals and hydro(oxides can be inner-and outer-sphere adsorbed. It is shown that the action of the metal bound to soil components becomes weakened in case of increasing the Cu and Zn load (from 2000 to 10000 mg/kg especially applied in the form of soluble salts. Extractive fractionation of metal compounds in chernozem samples, artificially contaminated with copper and zinc salts serves as evidence of absorbing the applied Cu2+ ions by the soil organic matter and Zn2+ ions – by silicates, carbonates, and Fe-Mn oxides.

  10. X-ray and γ-ray spectroscopy of solids under pressure

    International Nuclear Information System (INIS)

    Ingalls, R.L.

    1990-01-01

    This report briefly describes our studies of various materials at high pressures by means of x-ray and γ-ray absorption spectroscopy. High pressure provides a very effective means of studying materials. Virtually every property is altered from the color and crystal structure to the electrical and magnetic properties. The fundamental reason, of course, is that the quantum levels depend upon the atomic spacing so that both the electronic and vibrational structure is affected

  11. Investigating the evolution of local structure around Er and Yb in ZnO:Er and ZnO:Er, Yb on annealing using X-ray absorption spectroscopy

    Science.gov (United States)

    Anjana, R.; Jayaraj, M. K.; Yadav, A. K.; Jha, S. N.; Bhattacharyya, D.

    2018-04-01

    The local structure around Er and Yb centre in ZnO favouring upconversion luminescence was studied using EXAFS (Extended X-ray absorption fine structure spectroscopy). Due to the ionic radii difference between Zn and Er, Yb ions, the dopants cannot replace Zn in the ZnO lattice properly. Er2O3 and Yb2O3 impurity phases are formed at the grain boundaries of ZnO. It is found that the local structure around the Er centre in ZnO is modified on annealing in air. The symmetry around both erbium and ytterbium reduces with increase in annealing temperature. Symmetry reduction will favour the intra-4f transition and the energy transitions causing upconversion luminescence. By fitting the EXAFS data with theoretically simulated data, it is found that the Er centre forms a local structure similar to C4ν symmetry which is a distorted octahedron. On annealing the sample to 1200 °C, all the erbium centres are transformed to C4ν symmetry causing enhanced upconversion emission. Yb centre has also been modified on annealing. The decrease in co-ordination number with annealing temperature will decrease the symmetry and increase the near infrared absorption cross section. The decrease in symmetry around both the erbium and ytterbium centre and formation of C4ν symmetry around Er centre is the reason behind the activation of upconversion luminescence with high temperature annealing in both Er doped and Er, Yb co-doped ZnO samples. The study will be useful for the synthesis of high efficiency upconversion materials.

  12. Development of a spectro-electrochemical cell for soft X-ray photon-in photon-out spectroscopy

    Science.gov (United States)

    Ishihara, Tomoko; Tokushima, Takashi; Horikawa, Yuka; Kato, Masaru; Yagi, Ichizo

    2017-10-01

    We developed a spectro-electrochemical cell for X-ray absorption and X-ray emission spectroscopy, which are element-specific methods to study local electronic structures in the soft X-ray region. In the usual electrochemical measurement setup, the electrode is placed in solution, and the surface/interface region of the electrode is not normally accessible by soft X-rays that have low penetration depth in liquids. To realize soft X-ray observation of electrochemical reactions, a 15-nm-thick Pt layer was deposited on a 150-nm-thick film window with an adhesive 3-nm-thick Ti layer for use as both the working electrode and the separator window between vacuum and a sample liquid under atmospheric pressure. The designed three-electrode electrochemical cell consists of a Pt film on a SiC window, a platinized Pt wire, and a commercial Ag|AgCl electrode as the working, counter, and reference electrodes, respectively. The functionality of the cell was tested by cyclic voltammetry and X-ray absorption and emission spectroscopy. As a demonstration, the electroplating of Pb on the Pt/SiC membrane window was measured by X-ray absorption and real-time monitoring of fluorescence intensity at the O 1s excitation.

  13. Electronic structure of nanoscale Cu/Pt alloys: A combined X-ray diffraction and X-ray absorption investigations

    International Nuclear Information System (INIS)

    Chen Xing; Chu Wangsheng; Cai Quan; Xia Dingguo; Wu Zhonghua; Wu Ziyu

    2006-01-01

    PVP-protected Cu/Pt clusters were prepared by glycol/water reduction method and characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and absorption spectra. TEM and XRD analysis show that the Cu/Pt clusters with different molar ratio have fcc structure with particle size of about 4 nm, while the lattice parameters in these clusters reduce with increasing Cu concentration. From the X-ray absorption near edge structure (XANES) at Cu-K edge and Pt-L 2,3 edge, we demonstrate that the d-electronic states of Cu and Pt are affected by the local environment as a function of Cu/Pt molar ratio. With increasing Cu concentration, Pt loses a fraction of 5d electrons and the hybridization between p- and d-states at Cu sites is enhanced

  14. Electronic structure of nanoscale Cu/Pt alloys: A combined X-ray diffraction and X-ray absorption investigations

    Energy Technology Data Exchange (ETDEWEB)

    Chen Xing [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Graduate School of the Chinese Academy of Sciences, 100864 Beijing (China); Chu Wangsheng [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); University of Science and Technology of China, Hefei, 230036 (China); Cai Quan [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Graduate School of the Chinese Academy of Sciences, 100864 Beijing (China); Xia Dingguo [College of Environmental and Energy Engineering, Beijing University of Technology, 100022 Beijing (China); Wu Zhonghua [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China); Wu Ziyu [Beijing Synchrotron Radiation Facility, Institute of High Energy Physics, CAS, Beijing (China) and National Center for Nanoscience and Technology (China)]. E-mail: wuzy@ihep.ac.cn

    2006-11-15

    PVP-protected Cu/Pt clusters were prepared by glycol/water reduction method and characterized with transmission electron microscopy (TEM), X-ray diffraction (XRD) and absorption spectra. TEM and XRD analysis show that the Cu/Pt clusters with different molar ratio have fcc structure with particle size of about 4 nm, while the lattice parameters in these clusters reduce with increasing Cu concentration. From the X-ray absorption near edge structure (XANES) at Cu-K edge and Pt-L{sub 2,3} edge, we demonstrate that the d-electronic states of Cu and Pt are affected by the local environment as a function of Cu/Pt molar ratio. With increasing Cu concentration, Pt loses a fraction of 5d electrons and the hybridization between p- and d-states at Cu sites is enhanced.

  15. Modern X-ray spectroscopy 3. X-ray fluorescence holography

    International Nuclear Information System (INIS)

    Hayashi, Kouichi

    2008-01-01

    X-ray fluorescence holography (XFH) provides three dimensional atomic images around specified elements. The XFH uses atoms as a wave source or monitor of interference field within a crystal sample, and therefore it can record both intensity and phase of scattered X-rays. Its current performance makes it possible to apply to ultra thin film, impurity and quasicrystal. In this article, I show the theory including solutions for twin image problem, advanced measuring system, data processing for reconstruction of the atomic images and for obtaining accurate atomic positions, applications using resonant X-ray scattering and X-ray excited optical luminescence, and an example of XFH result on the local structure around copper in silicon steal. (author)

  16. Measurement of X-ray attenuation coefficients around K-absorption edges using Fe Kα X-rays

    International Nuclear Information System (INIS)

    Kerur, B.R.; Thontadarya, S.R.; Hanumaiah, B.

    1993-01-01

    The x-ray mass attenuation coefficients were measured around the K-absorption edges of elements in the range 16 ≤ Z ≤ 30 using Fe Kα x-rays of energy 6.400 keV, which is the weighted average energy of Kα 1 and Kα 2 x-ray components from the 57 Co radioactive source. Kβ x-rays were almost eliminated by the differential absorption technique. The small difference in energy between Kα 1 and Kα 2 , 13 eV, was shown to be inconsequential by comparing the measured and theoretical values of μ/ρ for standard materials such as Al, Cu, Mo and Ta. The effect of fine structure of the K-absorption edge on μ/ρ was elucidated by using the compounds of elements in the range 16 ≤ X ≤ 30, containing one element with its K-absorption edge energy (E k ) close to the incident photon energy (E x ). The results clearly indicate the validity of the theoretical mixture rule for all those compounds whose K edge is far away from the incident energy but show deviations of as much as 10% for the manganese compound whose K edge is 140 eV above E x and about 12% for the chromium compound whose K edge is 410 eV below E x . These deviations are attributed to the possible influence of resonance Raman scattering when the incident photon energy E x is less than the edge and to the influence of EXAFS when E x is more than the edge energy. (Author)

  17. In-situ x-ray absorption study of copper films in ground water solutions

    International Nuclear Information System (INIS)

    Kvashnina, K.O.; Butorin, S.M.; Modin, A.; Soroka, I.; Marcellini, M.; Nordgren, J.; Guo, J.-H.; Werme, L.

    2007-01-01

    This study illustrates how the damage from copper corrosion can be reduced by modifying the chemistry of the copper surface environment. The surface modification of oxidized copper films induced by chemical reaction with Cl - and HCO 3 - in aqueous solutions was monitored by in situ X-ray absorption spectroscopy. The results show that corrosion of copper can be significantly reduced by adding even a small amount of sodium bicarbonate. The studied copper films corroded quickly in chloride solutions, whereas the same solution containing 1.1 mM HCO 3 - prevented or slowed down the corrosion processes

  18. Coupled-cluster response theory for near-edge x-ray-absorption fine structure of atoms and molecules

    DEFF Research Database (Denmark)

    Coriani, Sonia; Christiansen, Ove; Fransson, Thomas

    2012-01-01

    triple corrected excitation energies CCSDR(3). This work is a first step toward the extension of these theoretical electronic structure methods of well-established high accuracy in UV-vis absorption spectroscopies to applications concerned with x-ray radiation. From the imaginary part of the linear...... response function, the near K-edge x-ray absorption spectra of neon, water, and carbon monoxide are determined and compared with experiment. Results at the CCSD level show relative peak intensities in good agreement with experiment with discrepancies in transition energies due to incomplete treatment...

  19. Thin film soft X-ray absorption filters

    International Nuclear Information System (INIS)

    Stattin, H.

    1992-11-01

    This report discusses the composition, reparation and performance of soft x-ray transmission filters for a water window soft x-ray microscope. Unbacked thin films of aluminum, silver and vanadium/aluminum were made by evaporation on a substrate from which they were released. Measured transmittances agree reasonably well with calculations. The report also includes some related theory and discussions about film preparation methods, film contamination and evaluation methods. 33 refs

  20. Absorption of X-rays in the interstellar medium

    International Nuclear Information System (INIS)

    Ride, S.K.; Stanford Univ., Calif.; Walker, A.B.C. Jr.; Stanford Univ., Calif.

    1977-01-01

    In order to interpret soft X-ray spectra of cosmic X-ray sources, it is necessary to know the photoabsorption cross-section of the intervening interstellar material. Current models suggest that the interstellar medium contains two phases which make a substantial contribution to the X-ray opacity: cool, relatively dense clouds that exist in pressure equilibrium with hot, tenuous intercloud regions. We have computed the soft X-ray photoabsorption cross-section (per hydrogen atom) of each of these two phases. The calculation are based on a model of the interstellar medium which includes chemical evolution of the galaxy, the formation of molecules and grains, and the ionization structure of each of each phase. These cross-sections of clouds and of intercloud regions can be combined to yield the total soft X-ray photoabsorption cross-section of the interstellar medium. By choosing the appropriate linear combination of cloud and intercloud cross-sections, we can tailor the total cross-section to a particular line-of-sight. This approach, coupled with our interstellar model, enables us to better describe a wide range of interstellar features such as H II regions, dense (molecular) clouds, or the ionized clouds which may surround binary X-ray sources. (orig.) [de

  1. Boron Doped diamond films as electron donors in photovoltaics: An X-ray absorption and hard X-ray photoemission study

    Energy Technology Data Exchange (ETDEWEB)

    Kapilashrami, M.; Zegkinoglou, I. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States); Conti, G.; Nemšák, S.; Conlon, C. S.; Fadley, C. S. [Department of Physics, University of California, Davis, California 95616 (United States); Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Törndahl, T.; Fjällström, V. [Ångström Solar Center, Uppsala University, Box 534, SE-751 21 Uppsala (Sweden); Lischner, J. [Department of Physics, University of California, Berkeley, California 94720 (United States); Louie, Steven G. [Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Department of Physics, University of California, Berkeley, California 94720 (United States); Hamers, R. J.; Zhang, L. [Department of Chemistry, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States); Guo, J.-H. [Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Himpsel, F. J., E-mail: fhimpsel@wisc.edu [Department of Physics, University of Wisconsin Madison, Madison, Wisconsin 53706 (United States)

    2014-10-14

    Highly boron-doped diamond films are investigated for their potential as transparent electron donors in solar cells. Specifically, the valence band offset between a diamond film (as electron donor) and Cu(In,Ga)Se₂ (CIGS) as light absorber is determined by a combination of soft X-ray absorption spectroscopy and hard X-ray photoelectron spectroscopy, which is more depth-penetrating than standard soft X-ray photoelectron spectroscopy. In addition, a theoretical analysis of the valence band is performed, based on GW quasiparticle band calculations. The valence band offset is found to be small: VBO=VBM{sub CIGS} – VBM{sub diamond}=0.3 eV±0.1 eV at the CIGS/Diamond interface and 0.0 eV±0.1 eV from CIGS to bulk diamond. These results provide a promising starting point for optimizing the band offset by choosing absorber materials with a slightly lower valence band maximum.

  2. Boron Doped diamond films as electron donors in photovoltaics: An X-ray absorption and hard X-ray photoemission study

    International Nuclear Information System (INIS)

    Kapilashrami, M.; Zegkinoglou, I.; Conti, G.; Nemšák, S.; Conlon, C. S.; Fadley, C. S.; Törndahl, T.; Fjällström, V.; Lischner, J.; Louie, Steven G.; Hamers, R. J.; Zhang, L.; Guo, J.-H.; Himpsel, F. J.

    2014-01-01

    Highly boron-doped diamond films are investigated for their potential as transparent electron donors in solar cells. Specifically, the valence band offset between a diamond film (as electron donor) and Cu(In,Ga)Se 2 (CIGS) as light absorber is determined by a combination of soft X-ray absorption spectroscopy and hard X-ray photoelectron spectroscopy, which is more depth-penetrating than standard soft X-ray photoelectron spectroscopy. In addition, a theoretical analysis of the valence band is performed, based on GW quasiparticle band calculations. The valence band offset is found to be small: VBO = VBM CIGS – VBM diamond  = 0.3 eV ± 0.1 eV at the CIGS/Diamond interface and 0.0 eV ± 0.1 eV from CIGS to bulk diamond. These results provide a promising starting point for optimizing the band offset by choosing absorber materials with a slightly lower valence band maximum.

  3. X-ray Spectroscopy and Magnetism in Mineralogy

    Science.gov (United States)

    Sainctavit, Philippe; Brice-Profeta, Sandrine; Gaudry, Emilie; Letard, Isabelle; Arrio, Marie-Anne

    The objective of this paper is to present the kind of information that can be gained in the field of mineralogy from the use of x-ray magnetic spectroscopies. We review some of the questions that are unsettled and that could benefit from an interdisciplinary approach where magnetism, spectroscopy and mineralogy could be mixed. Most of the attention is focused on iron and some other 3d transition elements. The mineralogy of planetary cores and its relation with known meteorites are exemplified. The various oxide phases in the mantle and the nature of iron in these phases is also underlined. The presence of transition elements in insulating minerals and its relation with macroscopic properties such as the color of gemstones are reviewed. Finally an introduction to paleomagnetism is given with a special attention to nanomaghemites.

  4. X-ray Absorption Spectroscopy and Density Functional Theory Studies of [(H3buea)FeIII-X]n1 (X= S2-, O2-,OH-): Comparison of Bonding and Hydrogen Bonding in Oxo and Sulfido Complexes

    Energy Technology Data Exchange (ETDEWEB)

    Dey, Abhishek; Hocking, Rosalie K.; /Stanford U., Chem. Dept.; Larsen, Peter; Borovik, Andrew S.; /Kansas U.; Hodgson, Keith O.; Hedman, Britt; Solomon, Edward I.; /SLAC,

    2006-09-27

    Iron L-edge, iron K-edge, and sulfur K-edge X-ray absorption spectroscopy was performed on a series of compounds [Fe{sup III}H{sub 3}buea(X)]{sup n-} (X = S{sup 2-}, O{sup 2-}, OH{sup -}). The experimentally determined electronic structures were used to correlate to density functional theory calculations. Calculations supported by the data were then used to compare the metal-ligand bonding and to evaluate the effects of H-bonding in Fe{sup III}-O vs Fe{sup III-}S complexes. It was found that the Fe{sup III-}O bond, while less covalent, is stronger than the FeIII-S bond. This dominantly reflects the larger ionic contribution to the Fe{sup III-}O bond. The H-bonding energy (for three H-bonds) was estimated to be -25 kcal/mol for the oxo as compared to -12 kcal/mol for the sulfide ligand. This difference is attributed to the larger charge density on the oxo ligand resulting from the lower covalency of the Fe-O bond. These results were extended to consider an Fe{sup IV-}O complex with the same ligand environment. It was found that hydrogen bonding to Fe{sup IV-}O is less energetically favorable than that to Fe{sup III-}O, which reflects the highly covalent nature of the Fe{sup IV-}O bond.

  5. Clocking Femtosecond Collisional Dynamics via Resonant X-Ray Spectroscopy

    Science.gov (United States)

    van den Berg, Q. Y.; Fernandez-Tello, E. V.; Burian, T.; Chalupský, J.; Chung, H.-K.; Ciricosta, O.; Dakovski, G. L.; Hájková, V.; Hollebon, P.; Juha, L.; Krzywinski, J.; Lee, R. W.; Minitti, M. P.; Preston, T. R.; de la Varga, A. G.; Vozda, V.; Zastrau, U.; Wark, J. S.; Velarde, P.; Vinko, S. M.

    2018-02-01

    Electron-ion collisional dynamics is of fundamental importance in determining plasma transport properties, nonequilibrium plasma evolution, and electron damage in diffraction imaging applications using bright x-ray free-electron lasers (FELs). Here we describe the first experimental measurements of ultrafast electron impact collisional ionization dynamics using resonant core-hole spectroscopy in a solid-density magnesium plasma, created and diagnosed with the Linac Coherent Light Source x-ray FEL. By resonantly pumping the 1 s →2 p transition in highly charged ions within an optically thin plasma, we have measured how off-resonance charge states are populated via collisional processes on femtosecond time scales. We present a collisional cross section model that matches our results and demonstrates how the cross sections are enhanced by dense-plasma effects including continuum lowering. Nonlocal thermodynamic equilibrium collisional radiative simulations show excellent agreement with the experimental results and provide new insight on collisional ionization and three-body-recombination processes in the dense-plasma regime.

  6. [Diffraction gratings used in x-ray spectroscopy]: Final report

    International Nuclear Information System (INIS)

    Smith, H.I.

    1988-01-01

    This subcontract was initiated in order to facilitate the development at MIT of technologies for fabricating the very fine diffraction grating required in x-ray spectroscopy at Lawrence Livermore Laboratory (LLL). These gratings are generally gold transmission gratings with spatial periods of 200 nm or less. The major focus of our efforts was to develop a means of fabricating gratings of 100 nm period. We explored two approaches: e-beam fabrication of x-ray lithography masks, and achromatic holographic lithography. This work was pursued by Erik Anderson as a major component of his Ph.D. thesis. Erik was successful in both the e-beam and holographic approaches. However, the e-beam method proved to be highly impractical: exposure times of about 115 days would be required to cover an area of 1 cm 2 . The achromatic holography, on the other hand, should be capable of exposing areas well in excess of 1 cm 2 in times under 1 hour. Moreover, 100 nm-period gratings produced by achromatic holography are coherent over their entire area whereas gratings produced by e-beam lithography are coherent only over areas /approximately/100 μm. The remainder of this report consists of portions excerpted from Erik Anderson's thesis. These contain all the details of our work on 100 nm period gratings. 26 refs., 17 figs

  7. The Advanced X-ray Spectroscopy and Imaging Observatory (AXSIO)

    Science.gov (United States)

    White, Nicholas E.; Bookbinder, Jay; Petre, Robert; Smith, Randall; Ptak, Andrew; Tananbaum, Harvey; Garcia, Michael

    2012-01-01

    Following recommendations from the 2010 "New Worlds, New Horizons" (NWNH) report, the Advanced X-ray Spectroscopy and Imaging Observatory (AXSIO) concept streamlines the International X-ray Observatory (IXO) mission to concentrate on the science objectives that are enabled by high-resolution spectroscopic capabilities. AXSIO will trace orbits close to the event horizon of black holes, measure black hole spin for tens of supermassive black holes (SMBH), use spectroscopy to characterize outflows and the environment of AGN during their peak activity, observe 5MBH out to redshift z=6, map bulk motions and turbulence in galaxy clusters, find the missing baryons in the cosmic web using background quasars, and observe the process of cosmic feedback where black holes and supernovae inject energy on galactic and intergalactic scales. These measurements are enabled by a 0.9 sq m collecting area at 1.25 keV, a micro calorimeter array providing high-resolution spectroscopic imaging and a deployable high efficiency grating spectrometer. AXSIO delivers a 30-fold increase in effective area for high resolution spectroscopy. The key simplifications are guided by recommendations in the NWNH panel report include a reduction in focal length from 20m to 10m, eliminating the extendable optical bench, and a reduction in the instrument complement from six to two, avoiding a movable instrument platform. A focus on spectroscopic science allows the spatial resolution requirement to be relaxed to 10 arc sec (with a 5 arc sec goal). These simplifications decrease the total mission cost to under the $2B cost to NASA recommended by NWNH. AXSIO will be available to the entire astronomical community with observing allocations based on peer-review.

  8. Microanalysis of iron oxidation state in iron oxides using X Ray Absorption Near Edge Structure (XANES)

    Science.gov (United States)

    Sutton, S. R.; Delaney, J.; Bajt, S.; Rivers, M. L.; Smith, J. V.

    1993-01-01

    An exploratory application of x ray absorption near edge structure (XANES) analysis using the synchrotron x ray microprobe was undertaken to obtain Fe XANES spectra on individual sub-millimeter grains in conventional polished sections. The experiments concentrated on determinations of Fe valence in a suite of iron oxide minerals for which independent estimates of the iron speciation could be made by electron microprobe analysis and x ray diffraction.

  9. Prospects for supermirrors in hard x-ray spectroscopy

    DEFF Research Database (Denmark)

    Joensen, Karsten D.; Gorenstein, Paul; Christensen, Finn Erland

    1994-01-01

    . The measured x-ray reflectivities are well accounted for by the standard dynamical theories of multilayer reflection. Hard x ray applications that could benefit from x-ray supermirror coatings inc