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1

Timepix detector at the X-ray Correlation Spectroscopy instrument at LCLS  

NASA Astrophysics Data System (ADS)

The Timepix detector can be operated in Time-over-Threshold mode to allow for charge integration measurements as required by short (< 50 fs) x-ray pulses of the Linac Coherent Light Source (LCLS). Initial commissioning activities have started at the X-ray Correlation Spectroscopy (XCS) instrument at LCLS, where speckle patterns have been measured.

van Bakel, N. A.; Robert, A.; Sikorski, M.; Ford, C.; van Beveren, V.; van der Heijden, B.; van Beuzekom, M.

2013-03-01

2

Deconvolving instrumental and intrinsic broadening in core-shell x-ray spectroscopies  

SciTech Connect

Intrinsic and experimental mechanisms frequently lead to broadening of spectral features in core-shell spectroscopies. For example, intrinsic broadening occurs in x-ray absorption spectroscopy (XAS) measurements of heavy elements where the core-hole lifetime is very short. On the other hand, nonresonant x-ray Raman scattering (XRS) and other energy loss measurements are more limited by instrumental resolution. Here, we demonstrate that the Richardson-Lucy (RL) iterative algorithm provides a robust method for deconvolving instrumental and intrinsic resolutions from typical XAS and XRS data. For the K-edge XAS of Ag, we find nearly complete removal of {approx}9.3 eV full width at half maximum broadening from the combined effects of the short core-hole lifetime and instrumental resolution. We are also able to remove nearly all instrumental broadening in an XRS measurement of diamond, with the resulting improved spectrum comparing favorably with prior soft x-ray XAS measurements. We present a practical methodology for implementing the RL algorithm in these problems, emphasizing the importance of testing for stability of the deconvolution process against noise amplification, perturbations in the initial spectra, and uncertainties in the core-hole lifetime.

Fister, T. T.; Seidler, G. T.; Rehr, J. J.; Kas, J. J.; Nagle, K. P. [Physics Department, University of Washington, Seattle, Washington 98105 (United States); Elam, W. T. [Applied Physics Laboratory, University of Washington, Seattle, Washington 98105 (United States); Cross, J. O. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)

2007-05-01

3

Photon excitation for satellite free x-ray spectroscopy: Instrumentation challenges  

SciTech Connect

First systematic study of satellites in x-ray emission spectra was performed by Deslattes using quasi-monochromatic photon excitation from a group of L{alpha} x-ray sources lying close to the K edge of Cl. He observed significant alterations in the Cl K{beta} spectrum of KCl depending on the character of the excitation radiation and identified the initial state of these satellites as a double vacancy state. Recently, the valence electronic structure of the chlorofluoromethanes were analyzed by chlorine K x-ray emission under satellite-free conditions. These studies were based on the use of synchrotron radiation to eliminate the multivacancy effects that are inherent in conventional x-ray spectroscopy. In this report, satellite free x-ray emission spectra from chlorofluoromethanes will be presented to demonstrate that the simplified spectra can be obtained using selective photon excitation. Results from various research groups world wide, utilizing the tunable photon excitation form synchrotron sources to eliminate the obscuring features in x-ray emission spectra of rare-gas solids (RGS) and metals will be discussed. Also, the technical challenges in utilizing the small phase-space attributes of high brightness from third generation SR sources producing x-ray and vacuum ultra-violet wavelengths to study weak features like satellites in x-ray emission spectra will be presented.

Perera, R.C.C.

1991-10-01

4

The MIT high resolution X-ray spectroscopy instruments on AXAF  

NASA Technical Reports Server (NTRS)

The general design and performance characteristics of MIT's two dispersive spectrometers, the Bragg Crystal Spectrometer (BCS) and the High Energy Transmission Grating Spectrometer (HETG), now being developed for the Advanced X-ray Astrophysics Facility (AXAF), are described. Particular attention is given to the development of the critical technologies incorporated into these instruments, including BCS diffractors, imaging gas flow proportional counters, and grating elements for the HETG. The principal stages and the current status of the developments are reviewed.

Canizares, C. R.; Dewey, D.; Galton, E. B.; Markert, T. H.; Smith, Henry I.; Schattenburg, M. L.; Woodgate, B. E.; Jordan, S.

1992-01-01

5

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

SciTech Connect

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{sub 1-x}Co{sub 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.

Huang, Chun-Chao; Chang, Shu-Jui; Yang, Chao-Yao; Tseng, Yuan-Chieh [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan (China)] [Department of Materials Science and Engineering, National Chiao Tung University, Hsinchu, Taiwan (China); Chou, Hsiung [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)] [Department of Physics, National Sun Yat-sen University, Kaohsiung, Taiwan (China)

2013-12-15

6

X-ray evolving universe spectroscopy mission (XEUS): narrow-field imaging high-resolution spectrometer instrument: I  

NASA Astrophysics Data System (ADS)

XEUS: The x-ray evolving universe spectroscopy mission aims to study the astrophysics of some of the most distant and hence youngest known discrete objects in the universe. In particular it specifically will measure the x-ray spectra of objects with a redshift z > 4 at flux levels below 10-17 erg cm-2s-1. At these high redshifts line emission from helium-like iron and oxygen which may be observed in the x-ray spectrum will be shifted down into the soft x-ray band. This places requirements on the spectral resolution and efficiency of any instrument in the focal plane which is to measure the detailed spectra of these faint sources and through the detection of these lines determine the redshift, distance and age. A narrow field low temperature imaging spectrometer covering the energy range 0.05-3 keV is currently considered as a possible element of the suite of focal plane instruments. This instrument, with a field of view of 0.5 arc minutes, an imaging capability matched to the XEUS optics of approximately 2-5 inches, will need to achieve an energy resolution of below approximately 2 eV at 500 eV. Currently a close packed large format array of superconducting tunnel junctions is envisaged operation at a temperature of approximately 30-350 mK. Such an array will be cooled by a closed cycle system comprising a mechanical cooler with a base temperature of 2.5 K and either a low temperature 3He sorption pump providing the very low temperature stage and/or an Adiabatic Demagnetization Refrigeration. In this paper we describe the key requirements of the XEUS low energy imaging spectrometer, the performance based on prototype designs together with soft x-ray test results of prototype arrays.

Verhoeve, Peter; Peacock, Anthony J.; Bavdaz, Markos; Martin, Didier D.; Rando, Nicola; Poelaert, Abel; den Hartog, Roland H.; Duband, Lionel

1999-09-01

7

X-ray astronomical spectroscopy  

NASA Technical Reports Server (NTRS)

The current status of the X-ray spectroscopy of celestial X-ray sources, ranging from nearby stars to distant quasars, is reviewed. Particular emphasis is placed on the role of such spectroscopy as a useful and unique tool in the elucidation of the physical parameters of the sources. The spectroscopic analysis of degenerate and nondegenerate stellar systems, galactic clusters and active galactic nuclei, and supernova remnants is discussed.

Holt, S. S.

1980-01-01

8

High resolution spectroscopy of X-ray emission from high mass X-ray binaries  

NASA Astrophysics Data System (ADS)

This article briefly reviews first the progress of spectroscopy in X-ray astronomy from proportional counters, a major instrument in early phase of X-ray astronomy, to gas scintillation proportional counters, X-ray CCD cameras, transmission and reflection gratings, and finally to X-ray micro-calorimeters. As a typical example of spectral features observed from high mass X-ray binaries (HMXBs), the spectra observed from Vela X-1 with Chandra grating spectrometers are then presented and compared with computer simulations for high mass binary systems.

Nagase, F.; Watanabe, S.

2006-01-01

9

X-ray absorption spectroscopy.  

PubMed

X-ray absorption spectroscopy (XAS) involves the excitation of core electrons to bound states localized on the photoabsorber and the eventual excitation of the photoelectron to the continuum. The resulting spectra are typically divided into two regions: (1) the edge region which provides electronic structure information and (2) the extended X-ray absorption fine structure (EXAFS) region, which provides information about the distance, number, and type of ligands. Here, a basic introduction to XAS theory, the information that can be obtained, and the experimental consideration are presented. The application of XAS to biological systems and the impact this has had on nitrogenase research are briefly highlighted. New experimental advances are described. PMID:21833867

Debeer, Serena

2011-01-01

10

Hard X-ray photoemission spectroscopy  

NASA Astrophysics Data System (ADS)

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 K? and Mg K? 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.

Kobayashi, Keisuke

2009-03-01

11

Resonant x-ray emission spectroscopy of liquid water: novel instrumentation, high resolution, and the"map" approach  

SciTech Connect

Techniques to study the electronic structure of liquids are rare. Most recently, resonant x-ray emission spectroscopy (XES) has been shown to be an extremely versatile spectroscopy to study both occupied and unoccupied electronic states for liquids in thermodynamic equilibrium. However, XES requires high-brilliance soft x-ray synchrotron radiation and poses significant technical challenges to maintain a liquid sample in an ultra-high vacuum environment. Our group has therefore developed and constructed a novel experimental setup for the study of liquids, with the long-term goal of investigating the electronic structure of biological systems in aqueous environments. We have developed a flow-through liquid cell in which the liquid is separated from vacuum by a thin Si3N4 or SiC window and which allows a precise control of temperature. This approach has significant advantages compared to static liquids cells used in the past. Furthermore, we have designed a dedicated high-transmission, high-resolution soft x-ray spectrometer. The high transmission makes it possible to measure complete resonant XES"maps" in less than an hour, giving unprecedented detailed insight into the electronic structure of the investigated sample. Using this new equipment we have investigated the electronic structure of liquid water. Furthermore, our XES spectra and maps give information about ultra-fast dissociation on the timescale of the O 1s core hole lifetime, which is strongly affected by the initial state hydrogen bonding configuration.

Weinhardt, L.; Fuchs, O.; Blum, M.; Bär, M.; Weigand, M.; Denlinger, J.D.; Zubavichus, Y.; Zharnikov, M.; Grunze, M.; Heske, C.; Umbach, E.

2008-06-17

12

Large Area X-ray Spectroscopy Mission  

NASA Astrophysics Data System (ADS)

The Large Area X-ray Spectroscopy (LAXS) mission study concept has evolved strongly over the last year culminating in the merging of LAXS with the Goddard Space Flight Center (GSFC) proposal for a similar mission, the Next Generation X-ray Observatory (NGXO, PI: Nick White). The resulting merger, re-named the High Throughput X-rays Spectroscopy (HTXS) Mission has also expanded by the inclusion of another SAO proposed new mission concept proposal, the Hard X-Ray Telescope (PI: Paul Gorenstein). The resultant multi-instrument mission retains much of heritage from the LAXS proposal, including the use of multiple satellites for robustness. These mergers resulted from a series of contacts between various team members, via e-mail, telecons, and in-person meetings. The impetus for the mergers was the fundamental similarity between the missions, and the recognition that all three proposal teams had significant contributions to make in the effort to define the next stage in the X-ray exploration of the universe. We have enclosed four items that represent some of the work that has occurred during the first year of the study: first, a presentation at the Leicester meeting, second a presentation that was made to Dan Goldin following the merging of LAXS and NGXO, third a copy of the first announcement for the Workshop, and finally the interim report that was prepared by the HTXS study team towards the end of the first year. This last document provides the foundation for the HTXS Technology Roadmap that is being generated. The HTXS roadmap will define the near-term goals that the merged mission must achieve over the next few years. A web site has been developed and populated that contains much of the material that has been generated over the past year.

Tananbaum, Harvey

1996-09-01

13

Current Status of AIST X-ray-Absorption-Spectroscopy (XAFS) Instrument with 100-Pixel Superconducting-Tunnel-Junction Array Detector  

NASA Astrophysics Data System (ADS)

We constructed a fluorescence yield X-ray absorption fine structure (XAFS) apparatus for the measurement of local structure around trace light element impurities in light element matrices. Our XAFS instrument with a 100-pixel STJ detector is now in the stage of routine operation and open to users at a synchrotron radiation facility (KEK PF). The average energy resolution of the 100 pixels is 11.8 0.6 at 400 eV in a sensitive area of 1 mm. As an example of functional materials, we successfully measured nitrogen K-edge XAFS spectra of a compound semiconductor, 4H-SiC, with a nitrogen dopant concentration of 300 ppm. The faint N-K line was clearly separated from the strong C-K line.

Shiki, S.; Ukibe, M.; Matsubayashi, N.; Zen, N.; Koike, M.; Kitajima, Y.; Ohkubo, M.

2014-08-01

14

Development of confocal micro X-ray fluorescence instrument using two X-ray beams  

Microsoft Academic Search

A new confocal micro X-ray fluorescence instrument was developed. This instrument has two independent micro X-ray tubes with Mo targets. A full polycapillary X-ray lens was attached to each X-ray tube. Another half polycapillary lens was attached to a silicon drift X-ray detector (SDD). The focal spots of the three lenses were adjusted to a common position. The effects of

Kouichi Tsuji; Kazuhiko Nakano; Xunliang Ding

2007-01-01

15

European XFEL: Soft X-Ray instrumentation  

SciTech Connect

The currently constructed European X-Ray Free Electron Laser (XFEL) will generate new knowledge in almost all the technical and scientific disciplines that are shaping our daily life-including nanotechnology, medicine, pharmaceutics, chemistry, materials science, power engineering and electronics. On 8 January 2009, civil engineering work (tunnels, shafts, halls) has been started at all three construction sites. In this presentation status and parameters of the European XFEL facility and instrumentation as well as planned research applications particularly in the range of soft X-rays are reviewed.

Molodtsov, S. L., E-mail: serguei.molodtsov@xfel.eu [European XFEL GmbH (Germany)

2011-12-15

16

Instrumentation for X-ray Astronomy  

NASA Technical Reports Server (NTRS)

Less than five decades ago, the first X-ray observations of the sky were made using simple devices such as film and geiger counters with crude collimators. These instruments were carried aloft by sounding rockets and made observations lasting only a few minutes at most. Today, orbiting observatories, utilizing high-resolution charged coupled devices (CCD's) at the focus of arc sec optics, have lifetimes measured in years. To maintain the pace of discovery in X-ray astronomy, detectors must continue to evolve into devices of ever increasing sensitivity and sophistication. Further progress depends upon a host of technologies: grazing incidence optics, proportional counters, semiconductors, calorimeters, etc. In this article we present a brief qualitative overview of these technologies and of the principles behind them, as well as some examples of how they are employed in scientific missions for X-ray observations at energies up to 100 keV.

Ramsey, Brian D.; Austin, Robert A.; Decher, Rudolf

1994-01-01

17

X-ray microprobe for micro x-ray fluorescence and absorption spectroscopies at GSECARS  

Microsoft Academic Search

The hard x-ray microprobe for x-ray fluorescence and absorption spectroscopy at GeoSoilEnviroCARS is presented. Using focused synchrotron radiation from an undulator beamline at the Advanced Photon Source at Argonne National Lab, the x-ray microprobe provides bright, monochromatic x-rays with typical spot sizes down to 1x1 mum for x-ray fluorescence and absorption spectroscopies. Quantitative x-ray fluorescence (XRF) analysis gives precise elemental

M. Newville; S. Sutton; M. Rivers

2002-01-01

18

Development of confocal micro X-ray fluorescence instrument using two X-ray beams  

NASA Astrophysics Data System (ADS)

A new confocal micro X-ray fluorescence instrument was developed. This instrument has two independent micro X-ray tubes with Mo targets. A full polycapillary X-ray lens was attached to each X-ray tube. Another half polycapillary lens was attached to a silicon drift X-ray detector (SDD). The focal spots of the three lenses were adjusted to a common position. The effects of the excitation of two X-ray beams were investigated. The instrument enabled highly sensitive three-dimensional X-ray fluorescence analysis. We confirmed that the X-ray fluorescence intensity from the sample increased by applying the two independent X-ray tubes in confocal configuration. Elemental depth profiling of black wheat was demonstrated with the result that each element in the surface coat of a wheat grain showed unique distribution.

Tsuji, Kouichi; Nakano, Kazuhiko; Ding, Xunliang

2007-07-01

19

X-ray absorption spectroscopy of metalloproteins.  

PubMed

Metalloproteins are enormously important in biology. While a variety of techniques exist for studying metals in biology, X-ray absorption spectroscopy is particularly useful in that it can determine the local electronic and physical structure around the metal center, and is one of the few avenues for studying "spectroscopically silent" metal ions like Zn(II) and Cu(I) that have completely filled valence bands. While X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) are useful for studying metalloprotein structure, they suffer the limitation that the detected signal is an average of all the various metal centers in the sample, which limits its usefulness for studying metal centers in situ or in cell lysates. It would be desirable to be able to separate the various proteins in a mixture prior to performing X-ray absorption studies, so that the derived signal is from one species only. Here we describe a method for performing X-ray absorption spectroscopy on protein bands following electrophoretic separation and western blotting. PMID:24639260

Ward, Jesse; Ollmann, Emily; Maxey, Evan; Finney, Lydia A

2014-01-01

20

X-ray spectroscopy from fusion plasmas  

Microsoft Academic Search

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

S. H. Glenzer

1999-01-01

21

X-ray spectroscopy from fusion plasmas  

Microsoft Academic Search

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

Glenzer

1998-01-01

22

X-ray photoelectron spectroscopy of conodonts  

Microsoft Academic Search

X-ray photoelectron spectroscopy is shown to be a useful technique for the analysis of the elemental and organic composition of microfossils such as conodonts. Changes in elemental and organic composition with depth from the conodont surface can be determined in order to establish origin and thermal maturity. In this work the organic matter in conodonts with a colour thermal maturity

Garry S. H Lee; G. Leong Mar; Harry R Rose; Craig P Marshall; Brent R Young; C. Gregory Skilbeck; Michael A Wilson

1998-01-01

23

Theoretical standards in x-ray spectroscopies  

SciTech Connect

We propose to extend our state-of-the-art, ab initio XAFS (X-ray absorption fine structure) codes, FEFF. Our current work has been highly successful in achieving accurate, user-friendly XAFS standards, exceeding the performance of both tabulated standards and other codes by a considerable margin. We now propose to add the capability to treat more complex materials. This includes multiple-scattering, polarization dependence, an approximate treatment of XANES (x-ray absorption near edge structure), and other improvements. We also plan to adapt FEFF to other spectroscopies, e.g. photoelectron diffraction (PD) and diffraction anomalous fine structure (DAFS).

Not Available

1992-01-01

24

Diamond detectors for x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

Polycrystalline diamond detector prototypes suitable for x-ray spectroscopy were realized and tested. Thick diamond specimens, mechanically polished to reduce the surface roughness, were selected for prototypes development. Noble metal contacts were deposited on both faces, whereas multistrip structures were defined by photolithography on the growth face only with the aim of reducing the coupling capacitances and to allow characterization tests either in planar or sandwich configuration. Leakage currents as low as 20 pA at 500 V were measured on a 270?m thick device. The x-ray sensitivity was tested monitoring the photocurrent as a function of the applied voltage under continuous 8.05 keV Cu K? irradiation. Studies in pulsed mode were also performed by using a commercial miniature x-ray source. Pulse height distributions were carried out with a system composed of a charge-sensitive preamplifier and a digital pulse processor multi-channel analyzer. Analysis was carried out around Ta L? and Cu K? characteristic lines. Realized prototypes were able to resolve such two characteristic lines only 90 eV apart. Energy resolutions better than 3% have been evaluated for one of the prototype at 8.14 keV. Such features address very good energy resolving capabilities and the suitability of polished polycrystalline diamond in x-ray spectroscopy.

Allegrini, P.; Girolami, M.; Calvani, P.; Conte, G.; Salvatori, S.; Spiriti, E.; Ralchenko, V.

2008-08-01

25

X-ray spectroscopy on tokamaks  

SciTech Connect

During the last decade, the x-ray spectroscopy of high temperature plasmas has witnessed a rapid development. Most of the impulses have come from astrophysics, in particular, from the research on solar flares. On the other hand, the attainment of well-diagnosed, high-temperature laboratory plasmas in laser-pellet implosions and in tokamaks, has precipitated a fertile exchange between theory and experiment. Agreement and very detailed understanding has been reached for a great number of spectra with the result, that x-ray spectroscopy represents today a powerful and reliable new plasma diagnostic with important applications for fusion plasmas as well as solar flares. This paper is a short review of the experimental results from tokamaks.

von Goeler, S.; Bitter, M.; Cohen, S.

1982-01-01

26

FOCAL: X-ray optics for accurate spectroscopy  

Microsoft Academic Search

A crystal spectrometer has been constructed in the Focusing Compensated Asymmetric Laue geometry covering the energy range between 30 and 120 keV. We summarize the crystal optics and show the usefulness of the instrument for spectroscopy of stationary and fast moving X-ray sources. Results are reported from several tests employing a 169Yb gamma-ray source and the Lyman radiation of one-electron

H. F. Beyer; Th. Stöhlker; D. Banas; D. Liesen; D. Protic; K. Beckert; P. Beller; J. Bojowald; F. Bosch; E. Förster; B. Franzke; A. Gumberidze; S. Hagmann; J. Hoszowska; P. Indelicato; O. Klepper; H.-J. Kluge; St. König; Chr. Kozhuharov; X. Ma; B. Manil; I. Mohos; A. Orsic-Muthig; F. Nolden; U. Popp; A. Simionovici; D. Sierpowski; U. Spillmann; Z. Stachura; M. Steck; S. Tachenov; M. Trassinelli; A. Warczak; O. Wehrhan; E. Ziegler

2004-01-01

27

X-ray spectroscopy of low-mass X-ray binaries  

NASA Astrophysics Data System (ADS)

I present high-resolution X-ray grating spectroscopy of neutron stars in low-mass X-ray binaries (LMXBs) using instruments onboard the Chandra X-ray Observatory and the X-ray Multi-Mirror Mission (XMM-Newton). The first part of this thesis concentrates on results from the subset of LMXBs with orbital periods less than an hour, known as ultracompact binaries. Previous low- resolution X-ray spectra of four systems (4U 0614+091, 2S 0918-549, 4U 1543-624, and 4U 1850-087) all contain a broad residual near 0.7 keV which had been attributed to unresolved line emission. I show that this residual is due to an incorrect model of the intervening photoelectric absorption and can be accounted for by allowing a non-standard Ne/O abundance ratio in the intervening material. I propose that there is neon-rich material local to each binary and that the mass donor is a low-mass, neon-rich degenerate dwarf in an ultracompact binary. Follow-up spectroscopy of 2S 0918-549 and 4U 1543-624 with the High Energy Transmission Grating Spectrometer (HETGS) onboard Chandra and the Reflection Grating Spectrometer onboard XMM confirms the excess neutral neon absorption. Interestingly, the Ne/O ratio of 4U 1543-624 varies by a factor of three between the Chandra and XMM observations, supporting the suggestion that some of the absorption originates local to the binaries. I also present X-ray spectroscopy of another ultracompact binary, the accretion-powered millisecond pulsar XTE J0929-314. No emission or absorption features are found in the high-resolution spectrum of this source, and the neutral absorption edge depths are consistent with the estimated interstellar absorption. The second part of this thesis uses LMXBs as probes of the interstellar medium (ISM). High-resolution X-ray studies of ISM absorption features can provide measurements of the relative abundances and ionization fractions of all the elements from carbon through iron. X-ray studies also probe the ISM on larger scales than is possible in the optical and ultraviolet wavebands. I present high-resolution spectroscopy of the oxygen K-shell ISM absorption edge in seven X- ray binaries using Chandra. The best-fit model consists of two absorption edges and five Gaussian absorption lines and can be explained by the recent theoretical calculations of K-shell absorption by neutral and ionized atomic oxygen. Significant oxygen features from dust or molecular components, suggested in previous studies, are not required by the Chandra spectra. These measurements also probe large-scale properties of the ISM, placing a limit on the velocity dispersion of the neutral lines of less than 200 km s-1 and constraining the interstellar ratio of O II/O I to approximately 0.1 and the ratio of O III/O I to less than 0.1. (Copies available exclusively from MIT Libraries, Rm. 14- 0551, Cambridge, MA 02139-4307. Ph. 617-253-5668; Fax 617-253-1690.)

Juett, Adrienne Marie

2004-10-01

28

Development and applications of grazing exit micro X-ray fluorescence instrument using a polycapillary X-ray lens  

Microsoft Academic Search

A polycapillary X-ray lens is an effective optics to obtain a ?m-size X-ray beam for micro-X-ray fluorescence spectrometry (?-XRF). We developed a ?-XRF instrument using a polycapillary X-ray lens, which also enabled us to perform Grazing Exit ?-XRF (GE-?-XRF). The evaluated diameter of the primary X-ray beam was 48 ?m at the focal distance of the X-ray lens. Use of

T. Emoto; Y. Sato; Y. Konishi; X. Ding; K. Tsuji

2004-01-01

29

Miniaturization in x ray and gamma ray spectroscopy  

NASA Technical Reports Server (NTRS)

The paper presents advances in two new sensor technologies and a miniaturized associated electronics technology which, when combined, can allow for very significant miniaturization and for the reduction of weight and power consumption in x-ray and gamma-ray spectroscopy systems: (1) Mercuric iodide (HgI2) x-ray technology, which allows for the first time the construction of truly portable, high-energy resolution, non-cryogenic x-ray fluorescence (XRF) elemental analyzer systems, with parameters approaching those of laboratory quality cryogenic instruments; (2) the silicon avalanche photodiode (APD), which is a solid-state light sensitive device with internal amplification, capable of uniquely replacing the vacuum photomultiplier tube in scintillation gamma-ray spectrometer applications, and offering substantial improvements in size, ruggedness, low power operation and energy resolution; and (3) miniaturized (hybridized) low noise, low power amplification and processing electronics, which take full advantage of the favorable properties of these new sensors and allow for the design and fabrication of advanced, highly miniaturized x-ray and gamma-ray spectroscopy systems. The paper also presents experimental results and examples of spectrometric systems currently under construction. The directions for future developments are discussed.

Iwanczyk, Jan S.; Wang, Yuzhong J.; Bradley, James G.

1993-01-01

30

Feasibility of in-line instruments for high-resolution inelastic X-ray scattering.  

PubMed

Inelastic X-ray scattering instruments in operation at third-generation synchrotron radiation facilities are based on backreflections from perfect silicon crystals. This concept reaches back to the very beginnings of high-energy-resolution X-ray spectroscopy and has several advantages but also some inherent drawbacks. In this paper an alternate path is investigated using a different concept, the `M(4) instrument'. It consists of a combination of two in-line high-resolution monochromators, focusing mirrors and collimating mirrors. Design choices and performance estimates in comparison with existing conventional inelastic X-ray scattering instruments are presented. PMID:21335910

Sturhahn, W; Toellner, T S

2011-03-01

31

New Developments in Femtosecond Soft X-ray Spectroscopy  

SciTech Connect

Recent instrumentation developments in X-ray spectroscopy for ultra-fast time-resolved measurements with soft X-rays done in HZB Berlin during the last years are described. The significant performance improvements achieved this way are based on Fresnel diffraction from structures being fabricated on a surface of a total externally reflecting mirror. The first type of this spectrometer, an off-axis reflection zone plate, has been implemented at the BESSY Femtoslicing setup and shows on the order of 20 times higher flux in the focal plane compared to the classical grating monochromator beamline. It has proven to serve very precise experiments with a time resolution down to 100 fs on magnetic materials after optical laser pulse excitation.

Erko, A.; Firsov, A.; Holldack, K. [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Elektronenspeicherring BESSY II, Albert Einstein str.15, Berlin (Germany)

2010-06-23

32

X-ray and EUV spectral instruments for plasma source characterization  

NASA Astrophysics Data System (ADS)

A set of spectral analytic instruments has been developed for absolute intensity measurements in a spectral range of 1 - 600 Å: (1) several modifications of grazing incidence spectrographs; (2) EUV monochromator- spectrometer with a constant angle of deviation; (3) focusing crystal von Hamos spectrometer using cylindrical mica and pyrolytic graphite crystals and a CCD linear array as a detector. These instruments are useful for plasma diagnostics, x-ray and EUV spectroscopy of laser-generated plasmas and capillary discharge plasmas, x-ray and EUV reflectometry, radiometry and x-ray fluorescence application.

Shevelko, Alexander P.; Kasyanov, Yuri S.; Knight, Larry V.; Phillips, James; Turley, R. Steven; Turner, D. Clark; Yakushev, Oleg F.

2004-01-01

33

X-ray Photoelectron Spectroscopy (XPS), Rutherford Back Scattering (RBS) studies  

NASA Technical Reports Server (NTRS)

X-ray photoelectron spectroscopy (XPS), Rutherford Back Scattering (RBS) studies of each of sample received were completed. Since low angle X-ray could not be performed because of instrumentation problems, Auger spectrometry was employed instead. The results of these measurements for each of the samples is discussed in turn.

Neely, W. C.; Bozak, M. J.; Williams, J. R.

1993-01-01

34

Development of a new total reflection X?ray fluorescence instrument using polycapillary X?ray lens  

Microsoft Academic Search

A new TXRF instrument combined with micro?XRF analytical technique was proposed. An X?ray micro?beam was obtained by using a polycapillary X?ray lens. The evaluated diameter of the X?ray beam at the focal distance was 35 ?m. In order to satisfy the total reflection condition of the present instrument, we attempted to cut the X?ray micro?beam above the critical angle of the

K. Nakano; K. Tanaka; X. Ding; K. Tsuji

2006-01-01

35

Synchrotron radiation, soft-X-ray spectroscopy andnanomaterials  

Microsoft Academic Search

Both synchrotron radiation based soft-X-ray absorption spectroscopy (XAS) and resonant soft-X-ray emission spectroscopy (XES) on a variety of nano-structured systems has yielded characteristic fingerprints. With high-resolution monochromatized synchrotron radiation excitation, resonant inelastic X-ray scattering (RIXS) has emerged as a new source of information about electronic structure and excitation dynamics of nanomaterials. The selectivity of the excitation, in terms of energy

Guo; Jinghua

2004-01-01

36

X-ray photoelectron spectroscopy peak assignment for perfluoropolyether oils  

NASA Technical Reports Server (NTRS)

Perfluoroalkylpolyether (PFPE) oils are increasingly being used as vacuum pump oils and as lubricants for magnetic recording media and instrumentation for satellites. In this paper, the relative binding energies of three PFPE oils are determined. When sample oils are continuously irradiated during X-ray spectroscopy (XPS) measurements, the relative peak intensity of the spectra is altered significantly, indicating that gaseous products form from the oils during XPS measurements. Thus, attention should be paid to chemical changes when XPE is used to characterize fluorinated carbons such as PFPE oils.

Mori, Shigeyuki; Morales, Wilfredo

1990-01-01

37

The Need for X-Ray Spectroscopy  

NASA Technical Reports Server (NTRS)

For over four decades, X-ray, EUV, and UV spectral observations have been used to measure physical properties of the solar atmosphere. During this time, there has been substantial improvement in the spectral, spatial, and temporal resolution of the observations for the EUV and UV wavelength ranges. At wavelengths below 100 Angstroms, however, observations of the solar corona with simultaneous spatial and spectral resolution are limited, and not since the late 1970's have spatially resolved solar X-ray spectra been measured. The soft-X-ray wavelength range is dominated by emission lines formed at high temperatures and provides diagnostics unavailable in any other wavelength range. In this presentation, we will discuss the important science questions that can be answered using spatially and spectrally resolved X-ray spectra.

Winebarger, Amy R.; Cirtain, Jonathan; Kobayashi, Ken

2011-01-01

38

X-ray ferromagnetic resonance spectroscopy  

SciTech Connect

We present a method to measure continuous-wave ferromagnetic resonance (FMR) spectra based on the core-level absorption of circularly polarized x rays. The technique is demonstrated by using a monochromatic x-ray beam incident on an yttrium-iron-garnet sample excited by a microwave field at 2.47 GHz. FMR spectra are obtained by monitoring the x-ray absorption intensity at the photon energy corresponding to the maximum of the magnetic circular dichroism effect at the iron L{sub 2,3} edges as a function of applied magnetic field. The x-ray FMR signal is shown to be energy dependent, which makes the technique element sensitive and opens up new possibilities to perform element-resolved FMR in magnetic alloys and multilayers.

Boero, G.; Rusponi, S.; Bencok, P.; Popovic, R.S.; Brune, H.; Gambardella, P. [Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland); European Synchrotron Radiation Facility (ESRF), F-38043 Grenoble (France); Ecole Polytechnique Federale de Lausanne (EPFL), CH-1015 Lausanne (Switzerland)

2005-10-10

39

Charge-Pump Detector for X-ray Correlation Spectroscopy  

SciTech Connect

A detector for the X-ray Correlation Spectroscopy (XCS) instrument at the Linac Coherent Light Source (LCLS) in Stanford (CA) is being developed at Brookhaven National Laboratory (BNL). The LCLS is the first operational X-ray free electron laser. It provides extremely bright coherent laser-like X-ray pulses with energy up to 8 keV, shorter than 100 fs and with a repetition rate that will go up to 120 Hz. An ideal detector for XCS experiments should cover a large angular range with high efficiency and provide a proper resolution to resolve the speckle. The requirement for dynamic range is not particularly stringent while a fast readout is needed. In particular, the Charge Pump Detector has to be highly efficient at the energy of 8 keV, provide a dynamic range of 100 photons and a readout noise much better than one photon. The 1024 x 1024 pixels have to be read within the repetition rate of the laser pulses, that is faster than 8 ms. The pixel size of 56 {micro} m x 56 {micro}m is a compromise between charge sharing and small pixel. Working principle and details of the detector will be discussed.

Carini, G.A.; Rehak, P.; Chen, W.; Siddons, D.P.

2011-01-15

40

Astrophysical X-Ray Spectroscopy: Then, Then Again, and Now  

Microsoft Academic Search

For the last three years, the grating experiments on Chandra and XMM-Newton have been providing magnificent spectra of nearly all classes of cosmic X-ray sources. In most cases, these are the very first high resolution X-ray spectra we have had available. As an introduction to this meeting on High Resolution X-ray Spectroscopy with XMM-Newton and Chandra, I thought it might

S. M. Kahn

2002-01-01

41

Miniaturization in x ray and gamma ray spectroscopy  

Microsoft Academic Search

The paper presents advances in two new sensor technologies and a miniaturized associated electronics technology which, when combined, can allow for very significant miniaturization and for the reduction of weight and power consumption in x-ray and gamma-ray spectroscopy systems: (1) Mercuric iodide (HgI2) x-ray technology, which allows for the first time the construction of truly portable, high-energy resolution, non-cryogenic x-ray

Jan S. Iwanczyk; Yuzhong J. Wang; James G. Bradley

1993-01-01

42

X-ray-induced photo-chemistry and X-ray absorption spectroscopy of biological samples.  

PubMed

As synchrotron light sources and optics deliver greater photon flux on samples, X-ray-induced photo-chemistry is increasingly encountered in X-ray absorption spectroscopy (XAS) experiments. The resulting problems are particularly pronounced for biological XAS experiments. This is because biological samples are very often quite dilute and therefore require signal averaging to achieve adequate signal-to-noise ratios, with correspondingly greater exposures to the X-ray beam. This paper reviews the origins of photo-reduction and photo-oxidation, the impact that they can have on active site structure, and the methods that can be used to provide relief from X-ray-induced photo-chemical artifacts. PMID:23093745

George, Graham N; Pickering, Ingrid J; Pushie, M Jake; Nienaber, Kurt; Hackett, Mark J; Ascone, Isabella; Hedman, Britt; Hodgson, Keith O; Aitken, Jade B; Levina, Aviva; Glover, Christopher; Lay, Peter A

2012-11-01

43

X-ray-induced photo-chemistry and X-ray absorption spectroscopy of biological samples  

PubMed Central

As synchrotron light sources and optics deliver greater photon flux on samples, X-ray-induced photo-chemistry is increasingly encountered in X-ray absorption spectroscopy (XAS) experiments. The resulting problems are particularly pronounced for biological XAS experiments. This is because biological samples are very often quite dilute and therefore require signal averaging to achieve adequate signal-to-noise ratios, with correspondingly greater exposures to the X-ray beam. This paper reviews the origins of photo-reduction and photo-oxidation, the impact that they can have on active site structure, and the methods that can be used to provide relief from X-ray-induced photo-chemical artifacts.

George, Graham N.; Pickering, Ingrid J.; Pushie, M. Jake; Nienaber, Kurt; Hackett, Mark J.; Ascone, Isabella; Hedman, Britt; Hodgson, Keith O.; Aitken, Jade B.; Levina, Aviva; Glover, Christopher; Lay, Peter A.

2012-01-01

44

Crystals for astronomical X-ray spectroscopy  

NASA Technical Reports Server (NTRS)

Crystal spectrometric properties and the factors that affect their measurement are discussed. Theoretical and experimental results on KAP are summarized and theoretical results based on the dynamical theory of X-ray diffraction are given for the acid phthalates as well as for the commonly used planes of ADP, PET and EDDT. Anomalous dispersion is found to be important for understanding the details of crystal Bragg reflection properties at long X-ray wavelengths and some important effects are pointed out. The theory of anomalous dispersion is applied to explain the anomalous reflectivity exhibited by KAP at 23.3 A.

Burek, A.

1976-01-01

45

Development of a new total reflection X-ray fluorescence instrument using polycapillary X-ray lens  

NASA Astrophysics Data System (ADS)

A new TXRF instrument combined with micro-XRF analytical technique was proposed. An X-ray micro-beam was obtained by using a polycapillary X-ray lens. The evaluated diameter of the X-ray beam at the focal distance was 35 ?m. In order to satisfy the total reflection condition of the present instrument, we attempted to cut the X-ray micro-beam above the critical angle of the total reflection with a slit. After the slit was applied, a clear critical angle could be observed. Using this proposed instrumental setup, we applied this to the analysis of a single particle on a flat Si substrate.

Nakano, K.; Tanaka, K.; Ding, X.; Tsuji, K.

2006-11-01

46

Spectroscopy and X-Ray Astronomy  

NASA Technical Reports Server (NTRS)

The new x-ray astronomical observatories have sufficient spectroscopic capability to allow the determination of plasma conditions in the form of velocities, temperatures, densities, and turbulence parameters at levels that were previously unattainable. The utilization of these diagnostics are possible only if the atomic and plasma physics are well-enough understood to match the observational sensitivity.

Holt, Stephen S.

2000-01-01

47

Method for X-ray fluorescence spectroscopy  

Microsoft Academic Search

A method and apparatus are described for performing X-ray fluorescence analysis where the physical relationship between the source\\/detector and the object being examined is not controlled. This technique and apparatus is particularly advantageous in performing an in situ analysis of the concentration of one or more elements present in a matrix of a material such as rock. In accordance with

W. C. Boyce; T. E. Hall; L. C. Howard; W. M. Lechelt; W. D. Wittekind

1985-01-01

48

Crystal optics for hard-X-ray spectroscopy of highly charged ions  

NASA Astrophysics Data System (ADS)

A twin crystal-spectrometer assembly, operated in the focusing compensated asymmetric Laue geometry has been developed for accurate spectroscopy of fast highly charged heavy ions in the hard-X-ray region. Coupled to the focusing crystal optics is a specially developed two-dimensional position-sensitive X-ray detector which is necessary for retaining spectral resolution also for fast moving sources. We summarize the crystal optics and demonstrate the usefulness of the instrument for spectroscopy of both stationary and fast moving X-ray sources. Results are reported from several tests employing a 169Yb gamma-ray source and the Lyman radiation of one-electron Pb 81+ ions traveling at a velocity corresponding to ? ? v/ c ? 0.59. The features of the instrument presented may be useful in many applications where it appears difficult to make the leap from conventional X-ray energy measurements to wavelength-dispersive spectroscopy based on crystal optics.

Beyer, H. F.; Attia, D.; Banas, D.; Le Bigot, E.-O.; Bosch, F.; Dousse, J.-Cl.; Förster, E.; Gumberidze, A.; Hagmann, S.; Heß, S.; Hoszowska, J.; Indelicato, P.; Jagodzinski, P.; Kozhuharov, Chr.; Krings, Th.; Liesen, D.; Ma, X.; Manil, B.; Mohos, I.; Pajek, M.; Proti?, D.; Reuschl, R.; Rzadkiewicz, J.; Simionovici, A.; Spillmann, U.; Stachura, Z.; Stöhlker, Th.; Trassinelli, M.; Trotsenko, S.; Warczak, A.; Wehrhan, O.; Ziegler, E.

2009-08-01

49

Beyond hard x-ray photoelectron spectroscopy: Simultaneous combination with x-ray diffraction  

SciTech Connect

Hard x-ray photoelectron spectroscopy (HAXPES) is a powerful and novel emerging technique for the nondestructive determination of electronic properties and chemical composition of bulk, buried interfaces and surfaces. It benefits from the exceptionally large escape depth of high kinetic energy photoelectrons, increasing the information depth up to several tens of nanometers. Complementing HAXPES with an atomic structure sensitive technique (such as x-ray diffraction) opens a new research field with major applications for materials science. At SpLine, the Spanish CRG beamline at the European Synchrotron Radiation Facility, we have developed a novel experimental set-up that combines HAXPES and x-ray diffraction (x-ray reflectivity, surface x-ray diffraction, grazing incidence x-ray diffraction, and reciprocal space maps). Both techniques can be operated simultaneously on the same sample and using the same excitation source. The set-up includes a robust 2S + 3D diffractometer hosting a ultrahigh vacuum chamber equipped with a unique photoelectron spectrometer (few eV < electron kinetic energy < 15 keV), x-ray tube (Mg/Ti), 15 keV electron gun, and auxiliary standard surface facilities (molecular beam epitaxy evaporator, ion gun, low energy electron diffraction, sample heating/cooling system, leak valves, load-lock sample transfer, etc.). This end-station offers the unique possibility of performing simultaneous HAXPES + x-ray diffraction studies. In the present work, we describe the experimental set-up together with two experimental examples that emphasize its outstanding capabilities: (i) nondestructive characterization of the Si/Ge and HfO{sub 2}/SiO{sub 2} interfaces on Ge-based CMOS devices, and (ii) strain study on La{sub 0.7}Ca{sub 0.3}MnO{sub 3} ultrathin films grown on SrTiO{sub 3}(001) substrate.

Rubio-Zuazo, Juan; Castro, German R. [SpLine, Spanish CRG beamline at the European Synchrotron Radiation Facility, B.P. 220, F-38043 Grenoble (France) and ICMM-CSIC Cantoblanco, E-28049 Madrid (Spain)

2013-05-15

50

Instrument and method for X-ray diffraction, fluorescence, and crystal texture analysis without sample preparation  

NASA Technical Reports Server (NTRS)

An X-ray diffraction and X-ray fluorescence instrument for analyzing samples having no sample preparation includes a X-ray source configured to output a collimated X-ray beam comprising a continuum spectrum of X-rays to a predetermined coordinate and a photon-counting X-ray imaging spectrometer disposed to receive X-rays output from an unprepared sample disposed at the predetermined coordinate upon exposure of the unprepared sample to the collimated X-ray beam. The X-ray source and the photon-counting X-ray imaging spectrometer are arranged in a reflection geometry relative to the predetermined coordinate.

Gendreau, Keith (Inventor); Martins, Jose Vanderlei (Inventor); Arzoumanian, Zaven (Inventor)

2010-01-01

51

Advanced X-ray Astrophysics Facility (AXAF) science instrumentation  

NASA Technical Reports Server (NTRS)

AXAF is to be equipped with a high performance X-ray telescope for the conduction of detailed astrophysics research. The observatory is to be serviced by the Space Station or the Shuttle, depending on capabilities during the AXAF operational period. The AXAF is to utilize the wavelength band from 1.2 A to 120 A. Attention is given to the AXAF science team, the AXAF observatory characteristics, the AXAF science instrument definition program, the Advanced Charge Coupled Device (CCD) Imaging Spectrometer (ACIS), the High Resolution Camera (HRC), the Bragg Crystal Spectrometer (BCS), the X-ray Spectrometer (XRS), the transmission gratings, and the program schedule.

Dailey, C. C.; Cumings, N. P.; Winkler, C. E.

1985-01-01

52

Soft X-ray induced damage in PVA-based membranes in water environment monitored by X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

The effect of synchrotron X-ray flux in a soft X-ray scanning-transmission microspectroscope (STXM) instrument on the chemical structure of air-filled poly(vinyl alcohol) (PVA) based microbubbles and their stabilizing shell has been examined. Prolonged soft X-ray illumination of the particles in aqueous suspension leads to the breaking of the microbubbles' protective polymer shell and substantial chemical changes. The latter were clarified via a micro-spot C K-edge near-edge X-ray absorption fine structure (NEXAFS) spectroscopy with further respect to the absorbed X-ray doses. Our results revealed a continuous degradation of the PVA network associated with formation of carbonyl- and carboxyl-containing species as well as an increased content of unsaturated bonds. The observed effects must be taken into account in studies of micro- and nanostructured polymer materials utilizing X-rays.

Tzvetkov, George; Späth, Andreas; Fink, Rainer H.

2014-10-01

53

Synchrotron radiation, soft-X-ray spectroscopy andnanomaterials  

SciTech Connect

Both synchrotron radiation based soft-X-ray absorption spectroscopy (XAS) and resonant soft-X-ray emission spectroscopy (XES) on a variety of nano-structured systems has yielded characteristic fingerprints. With high-resolution monochromatized synchrotron radiation excitation, resonant inelastic X-ray scattering (RIXS) has emerged as a new source of information about electronic structure and excitation dynamics of nanomaterials. The selectivity of the excitation, in terms of energy and polarization, has also facilitated studies of emission anisotropy. Various features observed in resonant emission spectra have been identified and studied.

Guo, Jinghua

2004-09-13

54

The Advanced X-ray Spectroscopy and Imaging Observatory (AXSIO)  

NASA Technical Reports Server (NTRS)

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.

White, Nicholas E.; Bookbinder, Jay; Petre, Robert; Smith, Randall; Ptak, Andrew; Tananbaum, Harvey; Garcia, Michael

2012-01-01

55

Development and applications of grazing exit micro X-ray fluorescence instrument using a polycapillary X-ray lens*1  

NASA Astrophysics Data System (ADS)

A polycapillary X-ray lens is an effective optics to obtain a ?m-size X-ray beam for micro-X-ray fluorescence spectrometry (?-XRF). We developed a ?-XRF instrument using a polycapillary X-ray lens, which also enabled us to perform Grazing Exit ?-XRF (GE-?-XRF). The evaluated diameter of the primary X-ray beam was 48 ?m at the focal distance of the X-ray lens. Use of this instrument enabled two-dimensional mapping of the elemental distributions during growth of the plant "Quinoa". The results of the mapping revealed elemental transition during growth. In addition, a small region of thin film was analyzed by GE-?-XRF. We expect that GE-?-XRF will become an effective method of estimating the film thickness of a small region.

Emoto, T.; Sato, Y.; Konishi, Y.; Ding, X.; Tsuji, K.

2004-08-01

56

The soft x-ray materials research (SXR) instrument at the Linac Coherent Light Source  

NASA Astrophysics Data System (ADS)

The soft x-ray materials science research (SXR) instrument completed commissioning in June 2010 and began experimental user operations shortly afterwards. This instrument delivers intense, ultra-short soft x-ray pulses from the Linac Coherent Light Source, the free-electron laser at the SLAC National Accelerator Laboratory. These are fully coherent and can contain up to 10^13 photons per pulse (or about 3 mJ per pulse) with bunch lengths from 300 femtoseconds down to sub-10 femtoseconds. The instrument includes a monochromator whose energy range spans energies from 480 eV - 2000 eV and a Kirkpatrick-Baez mirror system to create a focal spot of a few microns in diameter. The SXR instrument has a diverse set of end stations available to conduct a large variety of experimental techniques such as coherent imaging, resonant x-ray diffraction, photoelectron spectroscopy, and x-ray emission and/or absorption. First studies include fields spanning liquid femtosecond chemistry and time-resolved resonant inelastic x-ray scattering to ordering in solids and ultrafast magnetization. An overview of the instrument and its capabilities will be given.

Turner, Joshua J.; Krupin, Oleg; Schlotter, William

2011-03-01

57

Fast CCD camera for x-ray photon correlation spectroscopy and time-resolved x-ray scattering and imaging  

Microsoft Academic Search

A new, fast x-ray detector system is presented for high-throughput, high-sensitivity, time-resolved, x-ray scattering and imaging experiments, most especially x-ray photon correlation spectroscopy (XPCS). After a review of the architectures of different CCD chips and a critical examination of their suitability for use in a fast x-ray detector, the new detector hardware is described. In brief, its principal component is

P. Falus; M. A. Borthwick; S. G. J. Mochrie

2004-01-01

58

Soft x-ray spectroscopy study of nanoscale materials  

NASA Astrophysics Data System (ADS)

The ability to control the particle size and morphology of nanoparticles is of crucial importance nowadays both from a fundamental and industrial point of view considering the tremendous amount of high-tech applications. Controlling the crystallographic structure and the arrangement of atoms along the surface of nanostructured material will determine most of its physical properties. In general, electronic structure ultimately determines the properties of matter. Soft X-ray spectroscopy has some basic features that are important to consider. X-ray is originating from an electronic transition between a localized core state and a valence state. As a core state is involved, elemental selectivity is obtained because the core levels of different elements are well separated in energy, meaning that the involvement of the inner level makes this probe localized to one specific atomic site around which the electronic structure is reflected as a partial density-of-states contribution. The participation of valence electrons gives the method chemical state sensitivity and further, the dipole nature of the transitions gives particular symmetry information. The new generation synchrotron radiation sources producing intensive tunable monochromatized soft X-ray beams have opened up new possibilities for soft X-ray spectroscopy. The introduction of selectively excited soft X-ray emission has opened a new field of study by disclosing many new possibilities of soft X-ray resonant inelastic scattering. In this paper, some recent findings regarding soft X-ray absorption and emission studies of various nanostructured systems are presented.

Guo, Jinghua

2005-08-01

59

X-Ray Spectroscopy Using Low Temperature Detectors  

NASA Technical Reports Server (NTRS)

After several decades of development, a significant amount of the effort in low temperature detectors (LTDs) is concentrated on deploying real-world experiments. This has resulted from a great deal of basic detector physics performed by several generations of students, post-docs, and researchers. One of the most fruitful applications of LTDs is in non-dispersive x-ray spectroscopy. LTD x-ray spectrometers are broadband, efficient, moderately high-resolution, and can handle moderately high count rates. However, they require significantly more power, mass, and infrastructure compared to traditional solid state x-ray spectrometers, and cannot achieve, at least at low energies, the resolving powers achieved with dispersive spectrometers. In several fields, however, LTDs have or will make a significant contribution. In this review, we will discuss x-ray spectroscopy in general, the fields of science where LTDs are making a significant impact, and some of the current and near-term LTD spectrometers.

Porter, Frederick

2011-01-01

60

New focusing multilayer structures for X-ray plasma spectroscopy  

SciTech Connect

New focusing short-period multilayer structures are developed which opens up wide possibilities for X-ray and VUV spectroscopy. Multilayer structures are deposited on a flat surface of a mica crystal which is then bent to a small-radius cylinder. The use of this structure in a von Hamos spectrometer for X-ray laser plasma diagnostics is demonstrated. (interaction of laser radiation with matter. laser plasma)

Bibishkin, M S; Luchin, V I; Salashchenko, N N; Chernov, V V; Chkhalo, N I [Institute for Physics of Microstructures, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation); Kazakov, E D; Shevelko, A P [P.N. Lebedev Physics Institute, Russian Academy of Sciences, Moscow (Russian Federation)

2008-02-28

61

Small pixel CZT detector for hard X-ray spectroscopy  

Microsoft Academic Search

A new small pixel cadmium zinc telluride (CZT) detector has been developed for hard X-ray spectroscopy. The X-ray performance of four detectors is presented and the detectors are analysed in terms of the energy resolution of each pixel. The detectors were made from CZT crystals grown by the travelling heater method (THM) bonded to a 20×20 application specific integrated circuit

Matthew David Wilson; Robert Cernik; Henry Chen; Conny Hansson; Kris Iniewski; Lawrence L. Jones; Paul Seller; Matthew C. Veale

2011-01-01

62

Soft X-Ray and Vacuum Ultraviolet Based Spectroscopy of the Actinides  

SciTech Connect

The subjects of discussion included: VUV photoelectron spectroscopy, X-ray photoelectron spectroscopy, Synchrotron-radiation-based photoelectron spectroscopy, Soft x-ray absorption spectroscopy, Soft x-ray emission spectroscopy, Inverse photoelectron spectroscopy, Bremstrahlung Isochromat Spectroscopy, Low energy IPES, Resonant inverse photoelectron spectroscopy.

Tobin, J G

2011-03-17

63

Kinetic Inductance Detectors for X-Ray Spectroscopy  

NASA Astrophysics Data System (ADS)

The lack of efficient x-ray detectors is often the main factor limiting the effective use of ever more powerful synchrotron light sources. Spectroscopic X-ray detectors are used for a wide variety of synchrotron experiments including X-ray micro/nano-probes and X-ray absorption spectroscopy for biology and geophysical applications. The current state-of-art spectroscopic X-ray detectors are semiconductor devices, and their energy resolutions are approaching their theoretical limit of about 100 eV at 6 keV. We describe a detector research and development program to develop the next-generation of high-resolution spectroscopic X-ray detectors using superconducting Kinetic Inductance Detectors (KIDs). With a required energy per charge carrier four orders of magnitude smaller than that of Si, superconducting detectors offer up to two orders of magnitude increase in energy resolution. In addition, KIDs can be optimized for detection of photons ranging in energy from hard X-ray to IR.

Cecil, T.; Miceli, A.; Gades, L.; Datesman, A.; Quaranta, O.; Yefremenko, V.; Novosad, V.; Mazin, B.

64

[Development of Nanotechnology for X-Ray Astronomy Instrumentation  

NASA Technical Reports Server (NTRS)

This Research Grant provides support for development of nanotechnology for x-ray astronomy instrumentation. MIT has made significant progress in several development areas. In the last year we have made considerable progress in demonstrating the high-fidelity patterning and replication of x-ray reflection gratings. We developed a process for fabricating blazed gratings in silicon with extremely smooth and sharp sawtooth profiles, and developed a nanoimprint process for replication. We also developed sophisticated new fixturing for holding thin optics during metrology without causing distortion. We developed a new image processing algorithm for our Shack-Hartmann tool that uses Zernike polynomials. This has resulted in much more accurate and repeatable measurements on thin optics.

Schattenburg, Mark L.

2004-01-01

65

Femtosecond x-ray absorption spectroscopy with hard x-ray free electron laser  

SciTech Connect

We have developed a method of dispersive x-ray absorption spectroscopy with a hard x-ray free electron laser (XFEL), generated by a self-amplified spontaneous emission (SASE) mechanism. A transmission grating was utilized for splitting SASE-XFEL light, which has a relatively large bandwidth (?E/E ? 5 × 10{sup ?3}), into several branches. Two primary split beams were introduced into a dispersive spectrometer for measuring signal and reference spectra simultaneously. After normalization, we obtained a Zn K-edge absorption spectrum with a photon-energy range of 210 eV, which is in excellent agreement with that measured by a conventional wavelength-scanning method. From the analysis of the difference spectra, the noise ratio was evaluated to be ?3 × 10{sup ?3}, which is sufficiently small to trace minute changes in transient spectra induced by an ultrafast optical laser. This scheme enables us to perform single-shot, high-accuracy x-ray absorption spectroscopy with femtosecond time resolution.

Katayama, Tetsuo; Togashi, Tadashi; Tono, Kensuke; Kameshima, Takashi [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan)] [Japan Synchrotron Radiation Research Institute, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5198 (Japan); Inubushi, Yuichi; Sato, Takahiro; Hatsui, Takaki; Yabashi, Makina [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan)] [RIKEN SPring-8 Center, 1-1-1 Kouto, Sayo-cho, Sayo-gun, Hyogo 679-5148 (Japan); Obara, Yuki; Misawa, Kazuhiko [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan)] [Department of Applied Physics, Tokyo University of Agriculture and Technology, 2-24-16 Naka-cho, Koganei, Tokyo 184-8588 (Japan); Bhattacharya, Atanu; Kurahashi, Naoya [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan)] [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Ogi, Yoshihiro [Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan)] [Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan); Suzuki, Toshinori [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan) [Department of Chemistry, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyo-ku, Kyoto 606-8502 (Japan); Molecular Reaction Dynamics Research Team, RIKEN Center for Advanced Photonics, 2-1 Hirosawa, Wako 351-0198 (Japan)

2013-09-23

66

Diamond Photodetectors for X-Ray Absorption Spectroscopy Applications  

SciTech Connect

Synchrotron radiation (SR) is a fundamental tool for X-ray research. In particular, X-ray absorption spectroscopy (XAS) accesses information as electronic properties, local structure or chemical-physical state in condensed-matter studies. Ionization chambers (ICs) are the most widely used XAS detectors for transmission measurements because of their reliability, high linearity and good stability. Recently, solid-state detectors have been considered and Si p-i-n has been applied to high fluxes (10{sup 11} ph/s), where the linearity of ICs is no longer guaranteed. Silicon photodiodes exhibit an extremely linear response in at least 5 decades but show diffraction peaks. Diamond is an ideal substrate to produce radiation-hard, low dark current (<1 pA/cm{sup 2}), visible-blind and fast-response X-ray detectors with a high S/N ratio. Diamond detectors were tested as SR monitor capable to withstand the high photon flux density of the 3{sup rd} generation SR sources. Being the lowest X-ray-absorbing solid-state dielectric material, diamond maximizes the flux through thin self-standing devices with minimal spectral effect down to the soft x-ray range. We will present results of X-ray tests of photoconductors based on different diamond substrates. The results will be compared to standard ICs for XAS applications in terms of spectral quality, noise and linearity in the 4-13 keV energy range.

Pace, Emanuele; De Sio, Antonio [Dip. di Astronomia e Scienza dello Spazio, Universita di Firenze, L.go E. Fermi 2, 50125 Firenze (Italy); Pan Zhiyun; Wu Ziyu [National Synchrotron Radiation Laboratory, University of Science and Technology of China, Hefei 200023 (China); Marcelli, Augusto [INFN-Laboratori Nazionali di Frascati, Via E. Fermi 40, 00044, Frascati, Roma (Italy)

2010-06-23

67

Novel Approaches to Soft X-ray Spectroscopy: Scanning TransmissionX-ray Microscopy and Ambient Pressure X-Ray PhotoelectronSpectroscopy  

Microsoft Academic Search

This workshop focused on novel spectroscopies at Beamlines 11.0.2, 5.3.2 and 9.3.2 at the ALS. The workshop brought together users from a wide range of fields to highlight recent experimental and technical developments both in scanning transmission X-ray spectroscopy (STXM) and ambient pressure photoelectron spectroscopy (APPES). The morning session featured talks on experiments involving new developments at the STXM, while

Hendrik Bluhm; Mary K. Gilles; Simon B. Mun; Tolek Tyliszczak

2006-01-01

68

Advanced X-ray Astrophysics Facility (AXAF) science instruments  

NASA Technical Reports Server (NTRS)

The overall AXAF program is summarized, with particular emphasis given to its science instruments. The science objectives established for AXAF are to determine the nature of celestial objects, from normal stars to quasars, to elucidate the nature of the physical processes which take place in and between astronomical objects, and to shed light on the history and evolution of the universe. Attention is given to the AXAF CCD imaging spectrometer, which is to provide spectrally and temporally resolved imaging, or, in conjunction with transmission grating, high-resolution dispersed spectral images of celestial sources. A high-resolution camera, an X-ray spectrometer, and the Bragg Crystal Spectrometer are also discussed.

Winkler, Carl E.; Dailey, Carroll C.; Cumings, Nesbitt P.

1991-01-01

69

Focusing crystal von Hamos spectrometer for x-ray spectroscopy and x-ray fluorescence applications  

NASA Astrophysics Data System (ADS)

The use of bent crystals with high integrated reflectivity in focusing crystal spectrometers (Johann and von Hamos schemes) is considered. It is shown that in a von Hamos scheme mosaic focusing takes place. Thus a mosaic crystal simultaneously provides high spectral resolution and high efficiency. Expressions for the mosaic focusing are obtained. Focusing mica and graphite crystal von Hamos spectrometers (radius of crystal curvature is 20 mm) are investigated: spectral and spatial resolution and absolute efficiency are measured in a spectral range of 2 - 2.6 angstroms using laser-produced plasma and iron isotope x-ray sources. The mica crystal spectrometer showed high spatial (up to 10 micrometers ) and spectral ((lambda) /(delta) (lambda) approximately 1000) resolution, whereas the graphite spectrometer showed very high efficiency (30 - 70 times higher than the mica crystal) and moderate spectral resolution ((lambda) /(delta) (lambda) approximately 500 - 750). In the latter case mosaic focusing is observed: spectral resolution is 10 - 15 times higher than spectral resolution determined by the mosaic spread of the crystal ((lambda) /(delta) (lambda) approximately 50). The results allow one to estimate a maximum efficiency for focusing crystal spectrometers. Prospects for using the von Hamos spectrometers for x-ray spectroscopy and x-ray fluorescence are considered.

Shevelko, Alexander P.; Antonov, Alexander A.; Grigorieva, Inna G.; Kasyanov, Yury S.; Knight, Larry V.; Reyes-Mena, Arturo; Turner, Clark; Wang, Quan; Yakushev, Oleg F.

2000-11-01

70

X-ray Photoelectron Spectroscopy Database (Version 4.1)  

National Institute of Standards and Technology Data Gateway

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.

71

X-ray absorption spectroscopy of graphite oxide  

Microsoft Academic Search

We have investigated the electronic structure of graphite oxide using X-ray absorption spectroscopy at the carbon and oxygen K-edges. The unoccupied ?* and ?* states associated with sp2 hybridization in graphite, are also apparent in the graphite oxide, which indicates that it has a graphitic structure even though it experiences oxidation and annealing. Additional electronic states of the graphite oxide

H.-K. Jeong; H.-J. Noh; J.-Y. Kim; M. H. Jin; C. Y. Park; Y. H. Lee

2008-01-01

72

X-ray photoelectron spectroscopy and diffraction in the hard X-ray regime: Fundamental considerations and future possibilities  

NASA Astrophysics Data System (ADS)

The prospects for extending X-ray photoelectron spectroscopy (XPS) and X-ray photoelectron diffraction (XPD) measurements into the hard X-ray regime of 5-15 keV excitation energies are discussed from a fundamental point of view, in some cases using prior results obtained in the 1-2 keV range as starting points of discussion, together with theoretical estimates of behavior at higher energies. Subjects treated are: the instrumentation improvements needed to optimize peak intensities; the tuning of experimental conditions to achieve bulk or surface sensitivity; the use of grazing incidence to suppress spectral backgrounds; the use of standing waves created by Bragg reflection from crystal planes or synthetic multilayers to achieve position-sensitive densities of states, compositions, and magnetizations; photoelectron diffraction and Kikuchi-band effects as element-specific local structure probes; and valence-level measurements, including the role of non-dipole effects and mechanisms leading to complete Brillouin zone averaging and density-of-states like spectra. Several distinct advantages are found for such high-energy extensions of the XPS and XPD techniques.

Fadley, Charles S.

2005-07-01

73

Rolf Mewe: a career devoted to X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

An overview of the life and work of Rolf Mewe (1935-2004) as an X-ray spectroscopist is given. He was one of the pioneers in the field of X-ray spectroscopy. His work illustrates nicely how this field developed from the early days up to the present high-resolution era. His plasma emission codes, developed by him and collaborators over several decades, is one of the most widely used. His thorough knowledge of the field, as well as his ability and enthousiasm to cooperate with many colleagues, made his career a succes. He will be missed by all of us for his work and personality.

Kaastra, Jelle S.; Mewe, Rolf

2005-06-01

74

Biological X-ray absorption spectroscopy and metalloproteomics.  

PubMed

In the past seven years the size of the known protein sequence universe has been rapidly expanding. At present, more then five million entries are included in the UniProtKB/TrEMBL protein database. In this context, a retrospective evaluation of recent X-ray absorption studies is undertaken to assess its potential role in metalloproteomics. Metalloproteomics is the structural and functional characterization of metal-binding proteins. This is a new area of active research which has particular relevance to biology and for which X-ray absorption spectroscopy is ideally suited. In the last three years, biological X-ray absorption spectroscopy (BioXAS) has been included among the techniques used in post-genomics initiatives for metalloprotein characterization. The emphasis of this review is on the progress in BioXAS that has emerged from recent meetings in 2007-2008. Developments required to enable BioXAS studies to better contribute to metalloproteomics throughput are also discussed. Overall, this paper suggests that X-ray absorption spectroscopy could have a higher impact on metalloproteomics, contributing significantly to the understanding of metal site structures and of reaction mechanisms for metalloproteins. PMID:19395808

Ascone, Isabella; Strange, Richard

2009-05-01

75

28 CFR 552.13 - X-ray, major instrument, fluoroscope, or surgical intrusion.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false X-ray, major instrument, fluoroscope...and Inmate Work Areas § 552.13 X-ray, major instrument, fluoroscope...institution physician may authorize use of an X-ray for medical reasons and only...

2010-07-01

76

28 CFR 552.13 - X-ray, major instrument, fluoroscope, or surgical intrusion.  

Code of Federal Regulations, 2010 CFR

...2009-07-01 2009-07-01 false X-ray, major instrument, fluoroscope...and Inmate Work Areas § 552.13 X-ray, major instrument, fluoroscope...institution physician may authorize use of an X-ray for medical reasons and only...

2009-07-01

77

An upgraded x-ray spectroscopy diagnostic on MST  

SciTech Connect

An upgraded x-ray spectroscopy diagnostic is used to measure the distribution of fast electrons in MST and to determine Z{sub eff} and the particle diffusion coefficient D{sub r}. A radial array of 12 CdZnTe hard-x-ray detectors measures 10-150 keV Bremsstrahlung from fast electrons, a signature of reduced stochasticity and improved confinement in the plasma. A new Si soft-x-ray detector measures 2-10 keV Bremsstrahlung from thermal and fast electrons. The shaped output pulses from both detector types are digitized and the resulting waveforms are fit with Gaussians to resolve pileup and provide good time and energy resolution. Lead apertures prevent detector saturation and provide a well-known etendue, while lead shielding prevents pickup from stray x-rays. New Be vacuum windows transmit >2 keV x-rays, and additional Al and Be filters are sometimes used to reduce low energy flux for better resolution at higher energies. Measured spectra are compared to those predicted by the Fokker-Planck code CQL3D to deduce Z{sub eff} and D{sub r}.

Clayton, D. J.; Almagri, A. F.; Burke, D. R.; Forest, C. B.; Goetz, J. A.; Kaufman, M. C.; O'Connell, R. [Department of Physics, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

2010-10-15

78

What can be Learned from X-ray Spectroscopy Concerning Hot Gas in Local Bubble and Charge Exchange Processes?  

NASA Technical Reports Server (NTRS)

What can be learned from x-ray spectroscopy in observing hot gas in local bubble and charge exchange processes depends on spectral resolution, instrumental grasp, instrumental energy band, signal-to-nose, field of view, angular resolution and observatory location. Early attempts at x-ray spectroscopy include ROSAT; more recently, astronomers have used diffuse x-ray spectrometers, XMM Newton, sounding rocket calorimeters, and Suzaku. Future observations are expected with calorimeters on the Spectrum Roentgen Gamma mission, and the Solar Wind Charge Exchange (SWCX). The Geospheric SWCX may provide remote sensing of the solar wind and magnetosheath and remote observations of solar CMEs moving outward from the sun.

Snowden, Steve

2007-01-01

79

Interstellar medium composition through X-ray spectroscopy of low-mass X-ray binaries  

NASA Astrophysics Data System (ADS)

Context. The diffuse interstellar medium (ISM) is an integral part of the evolution of the entire Galaxy. Metals are produced by stars and their abundances are the direct testimony of the history of stellar evolution. However, the interstellar dust composition is not well known and the total abundances are yet to be accurately determined. Aims: We probe ISM dust composition, total abundances, and abundance gradients through the study of interstellar absorption features in the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs). Methods: We used high-quality grating spectra of nine LMXBs taken with XMM-Newton. We measured the column densities of O, Ne, Mg, and Fe with an empirical model and estimated the Galactic abundance gradients. Results: The column densities of the neutral gas species are in agreement with those found in the literature. Solids are a significant reservoir of metals like oxygen and iron. Respectively, 15-25% and 65-90% of the total amount of O i and Fe i is found in dust. The dust amount and mixture seem to be consistent along all the lines-of-sight (LOS). Our estimates of abundance gradients and predictions of local interstellar abundances are in agreement with those measured at longer wavelengths. Conclusions: Our work shows that X-ray spectroscopy is a very powerful method to probe the ISM. For instance, on a large scale the ISM appears to be chemically homogeneous showing similar gas ionization ratios and dust mixtures. The agreement between the abundances of the ISM and the stellar objects suggests that the local Galaxy is also chemically homogeneous.

Pinto, C.; Kaastra, J. S.; Costantini, E.; de Vries, C.

2013-03-01

80

Ultrafast X-ray diffraction and X-ray absorption spectroscopy  

Microsoft Academic Search

Summary form only given. Recently developed ultrafast laser-driven X-ray sources enable the observation of atomic motions in crystals and in solutions on the timescale of chemical bond formation and breakage. Using such a laboratory-based X-ray source the propagation of coherent phonon wave packets through GaAs(111) crystals after photo excitation has been imaged by ultrafast X-ray difraction. While ultrafast x-ray diffraction

C. Rose-Petruck

2000-01-01

81

Spectroscopy in X-ray astronomy using gas scintillation cameras  

Microsoft Academic Search

Experimental results obtained from a new, position sensitive, gas scintillation proportional counter are presented. The counter, for use in X-ray astronomy as a focal plane instrument in conjunction with a grazing incidence imaging telescope, features a useful aperture of about 7 cm, a two-stage scintillation region and a seven photomultiplier tube Anger camera read-out system. An energy resolution of not

B. G. Taylor; J. Davelaar; G. Manzo; A. Peacock

1981-01-01

82

X-ray photoelectron spectroscopy of aluminium-substituted tobermorite  

Microsoft Academic Search

We have synthesised 11-Å tobermorite hydrothermally, both pure and with increasing isomorphic substitution of aluminium for silicon. The samples were analysed by X-ray photoelectron spectroscopy (XPS). Aluminium was found, on the basis of its Al 2p binding energies, to be tetrahedrally coordinated. We observed no changes in Ca\\/(Si+Al) ratio upon aluminium substitution, implying that charge balancing does not occur via

Leon Black; Andreas Stumm; Krassimir Garbev; Peter Stemmermann; Keith R. Hallam; Geoffrey C. Allen

2005-01-01

83

High-Resolution Kaonic-Atom X-ray Spectroscopy with Transition-Edge-Sensor Microcalorimeters  

NASA Astrophysics Data System (ADS)

We are preparing for an ultra-high resolution X-ray spectroscopy of kaonic atoms using an X-ray spectrometer based on an array of superconducting transition-edge-sensor microcalorimeters developed by NIST. The instrument has excellent energy resolutions of 2-3 eV (FWHM) at 6 keV and a large collecting area of about 20 mm^2 . This will open new door to investigate kaon-nucleus strong interaction and provide new accurate charged-kaon mass value.

Okada, S.; Bennett, D. A.; Doriese, W. B.; Fowler, J. W.; Irwin, K. D.; Ishimoto, S.; Sato, M.; Schmidt, D. R.; Swetz, D. S.; Tatsuno, H.; Ullom, J. N.; Yamada, S.

2014-02-01

84

X-ray Intensity Fluctuation Spectroscopy Using Nanofocused Hard X-rays: Its Application to Study of Relaxor Ferroelectrics  

NASA Astrophysics Data System (ADS)

The use of a combination of coherent X-rays from a third-generation synchrotron light source and ultraprecise Kirkpatrick-Baez mirrors enables us to apply nanofocused hard X-rays in solid-state physics. We developed an apparatus for X-ray intensity fluctuation spectroscopy using the nanofocused hard X-rays and applied it to the study of relaxor ferroelectrics. We have successfully detected a large and slow intensity fluctuation of scattered X-rays above cubic-to-tetragonal phase transition temperature with a characteristic time scale on the order of 10 s. We speculated that the intensity fluctuation originates from domain number fluctuation, which is directly related to the dielectric response, particularly the frequency dispersion.

Kenji Ohwada,; Kazumichi Namikawa,; Susumu Shimomura,; Hironori Nakao,; Hidekazu Mimura,; Kazuto Yamauchi,; Mitsuyoshi Matsushita,; Jun'ichiro Mizuki,

2010-02-01

85

X-ray spectroscopy of the intermediate polar PQ Gem  

NASA Astrophysics Data System (ADS)

Using RXTE and ASCA data, we investigate the roles played by occultation and absorption in the X-ray spin pulse profile of the intermediate polar PQ Gem. From the X-ray light curves and phase-resolved spectroscopy, we find that the intensity variations are the result of a combination of varying degrees of absorption and the accretion regions rotating behind the visible face of the white dwarf. These occultation and absorption effects are consistent with those expected from the accretion structures calculated from optical polarization data. We can reproduce the changes in absorber covering fraction either from geometrical effects, or by considering that the material in the leading edge of the accretion curtain is more finely fragmented than in other parts of the curtain. We determine a white dwarf mass of ~ 1.2 using the RXTE data.

James, Cynthia H.; Ramsay, Gavin; Mark Cropper, Mark Cropper; Branduardi-Raymont, Graziella

2002-10-01

86

Closed source experimental system for soft x-ray spectroscopy of radioactive materials  

SciTech Connect

An instrumental and experimental setup for soft x-ray spectroscopy meeting the requirements of a closed source for radioactivity is described. The system consists of a vacuum sealed cell containing the sample, mounted on a tubing system to ensure compatibility with most standard manipulators. The soft x rays penetrate a thin x-ray window separating the interior of the cell from the vacuum in the experimental chamber. Our first results for single crystal PuO{sub 2} confirm the feasibility of experiments using the setup. The results are consistent with results of first principles calculations and previously recorded spectra obtained using a standard open source setup. The results show that the closed source experimental system can be used to collect valuable experimental data from radioactive materials.

Modin, A.; Butorin, S. M.; Vegelius, J.; Olsson, A.; Englund, C.-J.; Andersson, J.; Werme, L.; Nordgren, J. [Department of Physics, Uppsala University, P.O. Box 530, SE-751 21 Uppsala (Sweden); Kaeaembre, T. [Institute of Physics, University of Tartu, Riia 142 Tartu 51014 (Estonia); Skarnemark, G. [Nuclear Chemistry, Department of Chemical and Biological Engineering, Chalmers University of Technology, SE-412 96 Goeteborg (Sweden); Burakov, B. E. [Laboratory of Applied Mineralogy and Radiogeochemistry, V.G. Khlopin Radium Institute, St. Petersburg 194021 (Russian Federation)

2008-09-15

87

High-pressure behaviour of germanate olivines studied by X-ray diffraction and X-ray absorption spectroscopy  

Microsoft Academic Search

Germanate olivines Mg2GeO4, Ca2GeO4 and CaMgGeO4 have been studied by high-pressure X-ray Diffraction and high-pressure X-ray Absorption Spectroscopy. The three compounds were compressed, in the 0 30 GPa pressure range, at room temperature in a diamond-anvil cell, silicon oil being used as the pressure transmitting medium. Values of K0 are 166 ± 15, 117 ± 15 and 152 ± 14

P. E. Petit; F. Guyot; G. Fiquet; J. P. Itié

1996-01-01

88

Bent silicon crystal in the Laue geometry to resolve x-ray fluorescence for x-ray absorption spectroscopy.  

SciTech Connect

A highly strained, curved silicon crystal in the Laue geometry has been used as a large-area x-ray fluorescence analyzer for x-ray absorption spectroscopy. The analyzer is able to resolve the L{alpha} fluorescence lines for neighboring actinide elements. A large gain in the signal to background ratio has been demonstrated for small quantities of Np in the presence of U, with the U fluorescence peak approaching 1000 times the magnitude of the off-peak background.

Kropf, A. J.; Finch, R. J.; Fortner, J. A.; Aase, S. B.; Chemical Engineering

2003-11-01

89

The Astro-H Mission and High Resolution X-ray Spectroscopy  

NASA Astrophysics Data System (ADS)

The Japan Aerospace Exploration Agency's Institute of Space and Aeronautical Science (JAXA/ISAS) is developing a major new high-energy astrophysics observatory. Astro-H will provide broadband, high-resolution spectroscopy and imaging over the 0.3-600 keV band using four co-aligned instruments operated simultaneously. The mission will have major US participation supported by NASA as well as contributions from Europe and Canada. For high-resolution x-ray spectroscopy, the soft x-ray spectrometer (SXS) will feature an x-ray calorimeter spectrometer and x-ray mirror. The instrument will cover the energy range 0.3-12 keV and is expected to have an energy resolution better than 5 eV (FWHM) with a collecting area of over 200 cm2 at 6 keV. The cooling system will have both cryogenic and mechanical coolers for up to five years of operation. The SXS is a joint collaboration between NASA/GSFC, ISAS/JAXA and SRON, and the NASA participation was selected as an Explorers Mission of Opportunity in June 2008. As part of this investigation, a fully supported US guest observer program was also proposed and is under review by NASA. Other instruments on Astro-H include a soft x-ray imager (SXI) consisting of a large area CCD camera with 35 arcmin field-of-view and a hard x-ray imager (HXI) that uses focusing x-ray optics combined with both double-sided silicon strip detectors and CdTe array. The 12-m focal length optical system will provide an effective area of 300 cm2 at 30 keV, and high sensitivity from 10-80 keV using multilayer x-ray mirrors with 2-4 arcmin imaging. The soft gamma detector (SGD) is a non-focusing instrument based on a new, narrow-field-of-view Compton telescope with an energy range of 10-600 keV and sensitivity at 300 keV that is more than 10 times higher than Suzaku. Astro-H is planned for launch in 2014 aboard a JAXA HII-A rocket.

Kelley, Richard L.; Mitsuda, K.; Awaki, H.; Fujimoto, R.; den Herder, J. W.; Ishida, M.; Kilbourne, C. A.; Kunieda, H.; Maeda, Y.; McCammon, D.; Ohashi, T.; Okajima, T.; Porter, F.; Serlemitsos, P.; Soong, Y.; Szymkowiak, A. E.; Takahashi, T.; Takei, Y.; Tashiro, M.; Tawara, Y.; Yamasaki, N. Y.; Astro-H Collaboration

2010-02-01

90

Astrophysical X-Ray Spectroscopy: Then, Then Again, and Now  

NASA Astrophysics Data System (ADS)

For the last three years, the grating experiments on Chandra and XMM-Newton have been providing magnificent spectra of nearly all classes of cosmic X-ray sources. In most cases, these are the very first high resolution X-ray spectra we have had available. As an introduction to this meeting on High Resolution X-ray Spectroscopy with XMM-Newton and Chandra, I thought it might be fun to look back to where we came from, to get to where we are today in this field. I have chosen three snapshots in time: Then: Summer 1980 - I was driving across the U.S. (Berkeley to Boston). We had results from Uhuru, Ariel V, OSO 8, HEAO 1, and were just starting to get results from Einstein. Then Again: Summer 1995 - I was driving across the U.S. (Berkeley to NY). EXOSAT, BBXRT and ROSAT had flown in the interim. We were starting to get results from ASCA. Now: Summer 2002 - Chandra has been up for three years, XMM-Newton for 2 1/2. Astro-E tragically lost, but Astro-E2 in development.

Kahn, S. M.

2002-12-01

91

X-ray Absorption Spectroscopy in Mineralogy: A Review  

NASA Astrophysics Data System (ADS)

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).

Mottana, Annibale

2003-01-01

92

Advanced detection systems for X-ray fluorescence excitation spectroscopy.  

PubMed

This paper accounts for selected detector developments carried out over the past 15 years within the ESRF X-ray Absorption Spectroscopy group. This includes various types of photodiodes used as integrated current detectors. Special emphasis is put on the long-standing development of a Si drift-diode array suitable for energy-dispersive detection of X-ray fluorescence. This detector, which is now operational, was used to record high-quality XMCD/XAFS spectra on [Fe70Pt30] nanoparticles highly dispersed on a Si wafer. Using numerically deconvoluted spectra, energy resolution was decreased to 82 eV for the Si Kalphabeta line, 126 eV for the Fe Kalpha line and 176 eV for the Pt Lalpha line. A high-vacuum-compatible high-energy-resolution crystal analyzer was also installed on ID12, making it possible to record X-ray fluorescence excitation spectra in the photon-in/photon-out mode over a wide spectral range. Prospects of adapting these methods in order to investigate biological samples are briefly discussed. PMID:15616366

Goulon, J; Rogalev, A; Goujon, G; Gauthier, Ch; Moguiline, E; Solé, A; Feite, S; Wilhelm, F; Jaouen, N; Goulon-Ginet, Ch; Dressler, P; Rohr, P; Lampert, M-O; Henck, R

2005-01-01

93

EBIT x-ray spectroscopy studies for applications to photo-pumped x-ray lasers.  

National Technical Information Service (NTIS)

Several pumping mechanisms have been suggested for x-ray lasers including collisional excitation, recombination, photo-ionization and photo-pumping. The success of photo-pumping as an x-ray laser scheme hinges on sufficient overlap of the emission and ads...

S. R. Elliott P. Beiersdorfer J. Nilsen

1994-01-01

94

Fresnel lens arrays for x-ray imaging spectroscopy  

NASA Astrophysics Data System (ADS)

Arrays of achromatic Fresnel lenses are investigated for future high-resolution X-ray imaging missions. Unlike single-focus instruments, parallel arrangements of numerous tiny telescopes provide an easy and natural approach to spectroscopic observations in several energy bands, at an unprecedented short focal length of few 103 m. We suggest an optimized design with an angular resolution around 1 mas between 5 and 10 keV and analyze its optical capabilities as well as issues like the background problem which affects the achievable signal-to-noise ratio. An astronomical simulation is performed on the sun-like star Capella.

Braig, Christoph; Predehl, Peter

2010-07-01

95

X-Ray Absorption Spectroscopy of Uranium Dioxide  

SciTech Connect

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.

Tobin, J G

2010-12-10

96

Application of ultra-small-angle X-ray scattering / X-ray photon correlation spectroscopy to relate equilibrium or non-equilibrium dynamics to microstructure  

NASA Astrophysics Data System (ADS)

Ultra-small-angle X-ray scattering (USAXS) can probe microstructures over the nanometer-to-micrometer scale range. Through use of a small instrument entrance slit, X-ray photon correlation spectroscopy (XPCS) exploits the partial coherence of an X-ray synchrotron undulator beam to provide unprecedented sensitivity to the dynamics of microstructural change. In USAXS/XPCS studies, the dynamics of local structures in a scale range of 100 nm to 1000 nm can be related to an overall hierarchical microstructure extending from 1 nm to more than 1000 nm. Using a point-detection scintillator mode, the equilibrium dynamics at ambient temperature of small particles (which move more slowly than nanoparticles) in aqueous suspension have been quantified directly for the first time. Using a USAXS-XPCS scanning mode for non-equilibrium dynamics incipient processes within dental composites have been elucidated, prior to effects becoming detectable using any other technique.

Allen, Andrew; Zhang, Fan; Levine, Lyle; Ilavsky, Jan

2013-03-01

97

Pushing the boundaries of x-ray grating spectroscopy in a suborbital rocket  

NASA Astrophysics Data System (ADS)

The Off-Plane Grating Rocket Experiment (OGRE) will greatly advance the current capabilities of soft X-ray grating spectroscopy and provide an important technological bridge towards future X-ray observatories. The OGRE sounding rocket will fly an innovative X-ray spectrograph operating at resolving powers of R ~ 2000 and effective areas < 100 cm2 in the 0.2-1.5 keV bandpass. This represents a factor of two improvement in spectral resolution over currently operating instruments. OGRE will observe the astrophysical X-ray calibration source Capella, which has a linedominated spectrum and will showcase the full capabilities of the OGRE spectrograph. We outline the mission design for OGRE and provide detailed overviews of relevant technologies to be integrated into the payload, including slumped glass mirrors, blazed reflection gratings customized for the off-plane mount, and electron-multiplying CCDs (EMCCDs). The OGRE mission will bring these components to a high technology readiness level, paving the way for the use of such a spectrograph on future X-ray observatories or Explorer-class missions.

DeRoo, Casey; McEntaffer, Randall L.; Schultz, Ted; Zhang, William W.; Murray, Neil J.; O'Dell, Stephen L.; Cash, Webster

2013-09-01

98

Recent progress on the Constellation-X spectroscopy x-ray telescope (SXT)  

NASA Astrophysics Data System (ADS)

The Constellation X-ray Observatory consists of four identical spacecraft, each carrying a complement of high sensitivity X-ray instrumentation. At the heart of each is the grazing incidence mirror of the Spectroscopy X-ray Telescope (SXT). This mirror has a diameter of 1.6 m, a focal length of 10 m, mass not exceeding ~650 kg. The required angular resolution is 15 arc seconds and the effective area at 1 keV must exceed 7,500 cm2. Achieving these performance requirements in a cost effective way within the allocated mass is accomplished via a modular design, incorporating lightweight, multiply-nested, segmented Wolter Type I X-ray mirrors. The reflecting elements are composed of thin, thermally formed glass sheets, with epoxy-replicated X-ray reflecting surfaces. Co-alignment of groups of reflectors to the required sub-micron accuracy is assisted by precision silicon microstructures. Optical alignment incorporates the Centroid Detector Assembly (CDA) originally developed for aligning the Chandra mirror. In this talk we present an overview of recent progress in the SXT technology development program. Recent efforts have concentrated on producing an engineering unit that demonstrates all the key fabrication and alignment processes, and meets the angular resolution performance goal. Additionally, we describe the initial steps toward flight mirror production, anticipating a Constellation-X launch early in the next decade.

Petre, Robert; Content, David A.; O'Dell, Stephen L.; Owens, Scott M.; Podgorski, William A.; Stewart, Jeffrey W.; Saha, Timo T.; Zhang, William W.

2004-02-01

99

Femtosecond X-ray absorption spectroscopy at a hard X-ray free electron laser: application to spin crossover dynamics.  

PubMed

X-ray free electron lasers (XFELs) deliver short (<100 fs) and intense (?10(12) photons) pulses of hard X-rays, making them excellent sources for time-resolved studies. Here we show that, despite the inherent instabilities of 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 convoluted with the overall time resolution. The resulting time constant is ?160 fs. PMID:23281652

Lemke, Henrik T; Bressler, Christian; Chen, Lin X; Fritz, David M; Gaffney, Kelly J; Galler, Andreas; Gawelda, Wojciech; Haldrup, Kristoffer; Hartsock, Robert W; Ihee, Hyotcherl; Kim, Jeongho; Kim, Kyung Hwan; Lee, Jae Hyuk; Nielsen, Martin M; Stickrath, Andrew B; Zhang, Wenkai; Zhu, Diling; Cammarata, Marco

2013-01-31

100

Hubbard Model Approach to X-ray Spectroscopy  

NASA Astrophysics Data System (ADS)

We have implemented a Hubbard model based first-principles approach for real-space calculations of x-ray spectroscopy, which allows one to study excited state electronic structure of correlated systems. Theoretical understanding of many electronic features in d and f electron systems remains beyond the scope of conventional density functional theory (DFT). In this work our main effort is to go beyond the local density approximation (LDA) by incorporating the Hubbard model within the real-space multiple-scattering Green's function (RSGF) formalism. Historically, the first theoretical description of correlated systems was published by Sir Neville Mott and others in 1937. They realized that the insulating gap and antiferromagnetism in the transition metal oxides are mainly caused by the strong on-site Coulomb interaction of the localized unfilled 3d orbitals. Even with the recent progress of first principles methods (e.g. DFT) and model Hamiltonian approaches (e.g., Hubbard-Anderson model), the electronic description of many of these systems remains a non-trivial combination of both. X-ray absorption near edge spectra (XANES) and x-ray emission spectra (XES) are very powerful spectroscopic probes for many electronic features near Fermi energy (EF), which are caused by the on-site Coulomb interaction of localized electrons. In this work we focus on three different cases of many-body effects due to the interaction of localized d electrons. Here, for the first time, we have applied the Hubbard model in the real-space multiple scattering (RSGF) formalism for the calculation of x-ray spectra of Mott insulators (e.g., NiO and MnO). Secondly, we have implemented in our RSGF approach a doping dependent self-energy that was constructed from a single-band Hubbard model for the over doped high-T c cuprate La2-xSrxCuO4. Finally our RSGF calculation of XANES is calculated with the spectral function from Lee and Hedin's charge transfer satellite model. For all these cases our calculated x-ray spectra yield reasonable agreement with experiment. The above work has been implemented as an extension into the FEFF9 code, and we have also included notes for the new and modified key features of this development. Aside from the x-ray spectroscopy of correlated systems, we also present our calculation of the ground state local electronic structure of DNA nucleotides on graphene, and the transmission currents through graphene nanopores. Our calculation and analysis provide theoretical guidelines for developing DNA sequencing techniques using scanning tunneling spectroscopy (STS) and nanopore experiment. Evolved as a secondary focus of this thesis, we have added an additional chapter discussing our calculation of DNA-graphene hybrids.

Ahmed, Towfiq

101

The Future of X-ray Spectroscopy of Galactic Black Hole Binaries  

NASA Astrophysics Data System (ADS)

There are four major X-ray satellites currently in operation (RXTE, Chandra, XMM-Newton, INTEGRAL), with two more shortly to follow (Astro E II, Swift), and several very ambitious observatories in various stages of planning (Constellation-X, MAXIM, XEUS). This very rich period of X-ray observation is leading to great advances in our understanding of the accretion flow onto the black hole, although we are quickly learning (or perhaps better put, remembering) exactly how complicated this flow can be. This review was meant to assess future prospects for X-ray spectroscopy of black hole binaries; however, I first look backward to the observations and theories that helped us arrive at our current `paradigm'. I then discuss current and near-future spectroscopic studies, which increasingly (and very fruitfully) treat X-ray spectroscopy as part of a larger, intimately connected picture along with radio, optical, and gamma-ray spectroscopy. Equally importantly, and in large part thanks to the success of RXTE, there is now a strong realization that spectral-temporal correlations, even across wavelength bands, are crucial to our understanding of the physics of these systems. Going forward, we are well-poised to continue to advance our knowledge via X-ray spectroscopy, both with existing satellites that have a long lifetime ahead of them (Chandra, XMM-Newton, INTEGRAL), and with the next generation of instruments. If there is any `hole' in this bright future, it is the potential loss of RXTE, with no designated follow-up mission. Studies of multi-wavelength spectral-temporal correlations will become more difficult due to the loss of two important attributes of RXTE: its fast timing capabilities and its extremely flexible scheduling which has made many of these studies possible.

Nowak, Michael A.

2004-07-01

102

Femtosecond time-resolved X-ray absorption spectroscopy of liquid using a hard X-ray free electron laser in a dual-beam dispersive detection method.  

PubMed

We present femtosecond time-resolved X-ray absorption spectroscopy of aqueous solution using a hard x-ray free electron laser (SACLA) and a synchronized Ti:sapphire laser. The instrumental response time is 200 fs, and the repetition rate of measurement is 10 Hz. A cylindrical liquid beam 100 ?m in diameter of aqueous ammonium iron(III) oxalate solution is photoexcited at 400 nm, and the transient X-ray absorption spectra are measured in the K-edge region of iron, 7.10 - 7.26 keV, using a dual X-ray beam dispersive detection method. Each of the dual beams has the pulse energy of 1.4 ?J, and pump-induced absorbance change on the order of 10(-3) is successfully detected. The photoexcited iron complex exhibits a red shifted iron K-edge with the appearance time constant of 260 fs. The X-ray absorption difference spectra, with and without the pump pulses, are independent of time delay after 1.5 ps up to 100 ps, indicating that the photoexcited species is long-lived. PMID:24515070

Obara, Yuki; Katayama, Tetsuo; Ogi, Yoshihiro; Suzuki, Takayuki; Kurahashi, Naoya; Karashima, Shutaro; Chiba, Yuhei; Isokawa, Yusuke; Togashi, Tadashi; Inubushi, Yuichi; Yabashi, Makina; Suzuki, Toshinori; Misawa, Kazuhiko

2014-01-13

103

Research relative to high energy astrophysics. [large area modular array of reflectors, X-ray spectroscopy, and thermal control  

NASA Technical Reports Server (NTRS)

Various parameters which affect the design of the proposed large area modular array of reflectors (LAMAR) are considered, including thermal control, high resolution X-ray spectroscopy, pointing control, and mirror performance. The LAMAR instrument is to be a shuttle-launched X-ray observatory to carry out cosmic X-ray investigations. The capabilities of LAMAR are enumerated. Angular resolution performance of the mirror module prototype was measured to be 30 sec of ARC for 50% of the power. The LAMAR thermal pre-collimator design concepts and test configurations are discussed in detail.

Gorenstein, P.

1984-01-01

104

X-ray spectroscopy and imagery of supernova remnants with the Einstein Observatory  

NASA Technical Reports Server (NTRS)

The two complementary spectroscopic instruments of the Einsten Observatory make possible X-ray spectroscopy of SNRs with considerably increased sensitivity and spectral resolution. The Solid State Spectrometer is a cryogenically cooled detector with 160 eV resolution, which suffices not only for the separation of lines due to different elements, but also the resolution of H-like, He-like and neutral lines from the same element for Si and above. The Focal Plane Crystal Spectrometer uses Bragg crystals to achieve excellent spectral resolution, but at the expense of sensitivity. Both instruments operate over most of the 0.2-4 keV energy band of the Einstein telescope, and are able to detect most of the important X-ray lines except the K lines of Fe and Ni.

Winkler, P. F.; Markert, T. H.; Szymkowiak, A. E.; Canizares, C. R.

1982-01-01

105

X-ray photoelectron spectroscopy and x-ray excited Auger spectroscopy studies of manganese thiophosphate intercalated with sodium ions  

NASA Astrophysics Data System (ADS)

Polycrystalline powders of Na2xMn1-xPS3 have been synthesized from layered MnPS3 material by successive ion-exchange intercalation of potassium and sodium ions. Their x-ray photoelectron spectroscopy (XPS) and x-ray excited Auger spectroscopy spectra have been measured at room temperature using Mg K? (1253.6 eV) x-ray source. In particular, the Mn, P, and S 2p and Na 1s and 2p core-level regions and the Na Auger KL23L23 transition have been investigated. All the analyzed XPS core-level spectra display a single-peak structure, suggesting the absence of nonequivalent atoms of Na, Mn, P, and S. The manganese XPS spectrum shows, as observed in MnPS3 and in its cesium and potassium intercalation compounds, typical shake-up satellites, suggesting that the Mn-S bond is yet mainly ionic in nature. The comparison with the XPS spectra relative to MnPS3 and its potassium intercalation compound (K2xMn1-xPS3) does not emphasize any relevant difference in the binding energy positions of the investigated core levels, indicating that sodium ion intercalation process does not alter the electronic properties of pure host matrix. Moreover, Na 2p core levels are discrete and well localized in agreement with the hypothesis of a weak link between the guest (the Na+ ions) and the host lattice (the negatively charged Mn1-xPS3 sheets). Such a hypothesis finds confirmation by the calculation of the Na modified Auger parameter.

Silipigni, L.; Quattrone, T.; Schirò, L.; Grasso, V.; Scolaro, L. Monsù; de Luca, G.; Salvato, G.

2008-12-01

106

Double conical crystal x-ray spectrometer for high resolution ultrafast x-ray absorption near-edge spectroscopy of Al K edge  

Microsoft Academic Search

An x-ray spectrometer devoted to dynamical studies of transient systems using the x-ray absorption fine spectroscopy technique is presented in this article. Using an ultrafast laser-induced x-ray source, this optical device based on a set of two potassium acid phthalate conical crystals allows the extraction of x-ray absorption near-edge spectroscopy structures following the Al absorption K edge. The proposed experimental

A. Levy; F. Dorchies; C. Fourment; M. Harmand; S. Hulin; J. J. Santos; D. Descamps; S. Petit; R. Bouillaud

2010-01-01

107

Aqueous Cr(VI) reduction by pyrite: Speciation and characterisation of the solid phases by X-ray photoelectron, Raman and X-ray absorption spectroscopies  

Microsoft Academic Search

Optical microscopy, confocal Raman micro-spectrometry, X-ray photoelectron micro-spectroscopy (XPS) and synchrotron based micro-X-ray fluorescence (XRF), micro-X-ray absorption near edge spectroscopy (XANES) and micro-extended X-ray absorption fine structure (EXAFS) were used to investigate the reduction of aqueous Cr(VI) by pyrite. Special emphasis was placed on the characterisation of the solid phase formed during the reaction process. Cr(III) and Fe(III) species were

Martine Mullet; Frédéric Demoisson; Bernard Humbert; Laurent J. Michot; Delphine Vantelon

2007-01-01

108

(Diffraction gratings used in x-ray spectroscopy): Final report  

SciTech Connect

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/sup 2/. The achromatic holography, on the other hand, should be capable of exposing areas well in excess of 1 cm/sup 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 ..mu..m. 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.

Smith, H.I.

1988-11-01

109

X-Ray Absorption Spectroscopy Imaging of Biological Tissues  

SciTech Connect

X-ray absorption spectroscopy (XAS) is proving invaluable in determining the average chemical form of metals or metalloids in intact biological tissues. As most tissues have spatial structure, there is great additional interest in visualizing the spatial location of the metal(loid) as well as its chemical forms. XAS imaging gives the opportunity of producing maps of specific chemical types of elements in vivo in dilute biological systems. X-ray fluorescence microprobe techniques are routinely used to study samples with spatial heterogeneity. Microprobe produces elemental maps, with chemical sensitivity obtained by recording micro-XAS spectra at selected point locations on the map. Unfortunately, using these procedures spatial detail may be lost as the number of point spectra recorded generally is limited. A powerful extension of microprobe is XAS imaging or chemically specific imaging. Here, the incident energy is tuned to features in the near-edge which are characteristic of the expected chemical forms of the element. With a few simple assumptions, these XAS images can then be converted to quantitative images of specific chemical form, yielding considerable clarity in the distributions.

Pickering, Ingrid J.; George, Graham N. [Department of Geological Sciences, University of Saskatchewan, 114 Science Place, Saskatoon, SK, S7N 4R5 (Canada)

2007-02-02

110

X-Ray Absorption Spectroscopy Imaging of Biological Tissues  

SciTech Connect

X-ray absorption spectroscopy (XAS) is proving invaluable in determining the average chemical form of metals or metalloids in intact biological tissues. As most tissues have spatial structure, there is great additional interest in visualizing the spatial location of the metal(loid) as well as its chemical forms. XAS imaging gives the opportunity of producing maps of specific chemical types of elements in vivo in dilute biological systems. X-ray fluorescence microprobe techniques are routinely used to study samples with spatial heterogeneity. Microprobe produces elemental maps, with chemical sensitivity obtained by recording micro-XAS spectra at selected point locations on the map. Unfortunately, using these procedures spatial detail may be lost as the number of point spectra recorded generally is limited. A powerful extension of microprobe is XAS imaging or chemically specific imaging. Here, the incident energy is tuned to features in the near-edge which are characteristic of the expected chemical forms of the element. With a few simple assumptions, these XAS images can then be converted to quantitative images of specific chemical form, yielding considerable clarity in the distributions.

Pickering, I.J.; George, G.N.

2009-06-05

111

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

SciTech Connect

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.

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.

2011-05-01

112

Correlated Single-Crystal Electronic Absorption Spectroscopy and X-ray Crystallography at NSLS Beamline X26-C  

SciTech Connect

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.

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

2011-12-31

113

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

PubMed Central

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.

Orville, Allen M.; Buono, Richard; Cowan, Matt; Heroux, Annie; Shea-McCarthy, Grace; Schneider, Dieter K.; Skinner, John M.; Skinner, Michael J.; Stoner-Ma, Deborah; Sweet, Robert M.

2011-01-01

114

Polytetrafluoroethylene transfer film studied with X-ray photoelectron spectroscopy  

NASA Technical Reports Server (NTRS)

Polytetrafluoroethylene (PTFE) was rubbed against nickel in ultrahigh vacuum at loads up to 3.9 N and speeds up to 94 mm/sec. The transfer film formed on the nickel was analyzed using X-ray phototectron spectroscopy. The film was indistinguishable from bulk PTFE except for the possible presence of a small amount of NiF2. The transfer film was found to be about 1 molecule (0.5 nm) thick under all conditions; but at speeds above 10 mm/sec, there was evidence of bulk transfer in the form of fragments as well. The thickness measurements required a choice among conflicting published values of the inelastic mean free path for electrons in polymers. The values chosen gave internally consistent results.

Wheeler, D. R.

1980-01-01

115

Imide photodissociation investigated by X-ray absorption spectroscopy.  

PubMed

X-ray absorption spectroscopy is used to investigate the photodissociation of the imides PMDI (pyromellitic diimide) and SSMCC (sulfosuccinimidyl 4-(N-maleimidomethyl) cyclohexane-1-carboxylate). PMDI contains only one type of imide, and its photodissociation can be explained by a simple conversion from imide to a mix of imine and nitrile after desorption of the oxygens from the imide. SSMCC contains two different imides. One reacts like PMDI, the other in a more complex multistep process. Eventually, N(2) is formed in the bulk of the sample at high radiation density. The sequence of reactions is inferred from the ?* peaks in total electron yield and fluorescence yield absorption spectra at the N 1s and O 1s edges. First-order rate equations are used to model the evolution of the peak areas versus radiation dose. PMID:22594563

Johnson, Phillip S; Cook, Peter L; Liu, Xiaosong; Yang, Wanli; Bai, Yiqun; Abbott, Nicholas L; Himpsel, F J

2012-06-21

116

X-ray imaging-spectroscopy of Abell 1835  

NASA Astrophysics Data System (ADS)

We present detailed spatially-resolved spectroscopy results of the observation of Abell 1835 using the European Photon Imaging Cameras (EPIC) and the Reflection Grating Spectrometers (RGS) on the XMM-Newton observatory. Abell 1835 is a luminous (1046 ergs {s}-1), medium redshift (z=0.2523), X-ray emitting cluster of galaxies. The observations support the interpretation that large amounts of cool gas are present in a multi-phase medium surrounded by a hot (kT{e}=8.2 keV) outer envelope. We detect O VIII Lyalpha and two Fe XXIV complexes in the RGS spectrum. The emission measure of the cool gas below kT{e}=2.7 keV is much lower than expected from standard cooling-flow models, suggesting either a more complicated cooling process than simple isobaric radiative cooling or differential cold absorption of the cooler gas.

Peterson, J. R.; Paerels, F. B. S.; Kaastra, J. S.; Arnaud, M.; Reiprich, T. H.; Fabian, A. C.; Mushotzky, R. F.; Jernigan, J. G.; Sakelliou, I.

2001-01-01

117

X-Ray Imaging-Spectroscopy of Abell 1835  

NASA Technical Reports Server (NTRS)

We present detailed spatially-resolved spectroscopy results of the observation of Abell 1835 using the European Photon Imaging Cameras (EPIC) and the Reflection Grating Spectrometers (RGS) on the XMM-Newton observatory. Abell 1835 is a luminous (10(exp 46)ergs/s), medium redshift (z = 0.2523), X-ray emitting cluster of galaxies. The observations support the interpretation that large amounts of cool gas are present in a multi-phase medium surrounded by a hot (kT(sub e) = 8.2 keV) outer envelope. We detect O VIII Ly(alpha) and two Fe XXIV complexes in the RGS spectrum. The emission measure of the cool gas below kT(sub e) = 2.7 keV is much lower than expected from standard cooling-flow models, suggesting either a more complicated cooling process than simple isobaric radiative cooling or differential cold absorption of the cooler gas.

Peterson, J. R.; Paerels, F. B. S.; Kaastra, J. S.; Arnaud, M.; Reiprich T. H.; Fabian, A. C.; Mushotzky, R. F.; Jernigan, J. G.; Sakelliou, I.

2000-01-01

118

Effect of regolith on planetary X-ray fluorescence spectroscopy: laboratory and numerical studies  

Microsoft Academic Search

Fluorescent X-rays from the surfaces of airless planetary bodies in the inner solar system have been measured by instruments on several spacecraft. X-ray emission follows photoionisation by incident solar X-rays and charged particles and reveals the elemental composition of the surface. Analyses of X-ray spectra obtained by orbiting spacecraft, use the relative intensities of elemental emission lines (e.g., Ca\\/Si, Fe\\/Si)

Jyri Naranen; James Carpenter; Hannu Parviainen; Karri Muinonen

2008-01-01

119

Synchrotron Radiation X-ray Diffraction and X-ray Photoelectron Spectroscopy Investigation on Si-based Structures for SubMicron Si-IC Applications  

Microsoft Academic Search

Synchrotron radiation X-ray diffraction and X-ray photoelectron spectroscopy techniques have been employed for the investigation on Si-based layer structures for sub-micron Si-IC Applications. The high energy synchrotron radiation light sources have produced plenty of X-ray lines with high index diffraction and strong X-ray photoelectron emissions. The useful information will increase our understanding of these materials which are applied extensively to

Zhe Chuan Feng; Li-Chi Cheng; Chu-Wan Huang; Ying-Lang Wang; T. R. Yang

2006-01-01

120

X-ray-excited optical luminescence of erbium-doped semiconductor: site-selective X-ray absorption spectroscopy of an optically active atom  

Microsoft Academic Search

The X-ray-excited optical luminescence (XEOL) of erbium-doped silicon (Si:Er) thin film is observed for the site-selective X-ray absorption spectroscopy (XAS) of an optically active Er atom. In order to achieve the site-selectivity at the atomic level, intense X-ray from an undulator is used for the excitation of Er. Indirect excitation caused by X-ray absorption at Si around Er is investigated,

M. Ishii; Y. Tanaka; S. Komuro; T. Morikawa; Y. Aoyagi; T. Ishikawa

2001-01-01

121

A new tool for nanoscale X-ray absorption spectroscopy and element-specific SNOM microscopy.  

PubMed

Investigations of complex nanostructured materials used in modern technologies require special experimental techniques able to provide information on the structure and electronic properties of materials with a spatial resolution down to the nanometer scale. We tried to address these needs through the combination of X-ray absorption spectroscopy (XAS) using synchrotron radiation microbeams with scanning near-field optical microscopy (SNOM) detection of the X-ray excited optical luminescence (XEOL) signal. The first results obtained with the prototype instrumentation installed at the European Synchrotron Radiation Facility (Grenoble, France) are presented. They illustrate the possibility to detect an element-specific contrast and to perform nanoscale XAS experiments at the Zn K and W L(3)-absorption edges in pure ZnO and mixed ZnWO(4)/ZnO thin films. PMID:18328717

Larcheri, S; Rocca, F; Pailharey, D; Jandard, F; Graziola, R; Kuzmin, A; Kalendarev, R; Purans, J

2009-01-01

122

High resolution X-ray spectroscopy of massive stars  

NASA Astrophysics Data System (ADS)

This thesis presents studies of high-resolution X-ray spectra of massive stars. Diffraction grating spectrometers onboard the XMM- Newton and Chandra satellite X-ray observatories have revolutionized our understanding of X-ray emission from massive stars, allowing the resolution of individual spectral lines and the study of their Doppler profiles. I discuss the use of line strengths and ratios to constrain temperature distributions, elemental abundances, and distribution of X-ray emitting plasma near a star. I also discuss the interpretation of Doppler profiles in light of their unexpected lack of asymmetry.

Leutenegger, Maurice Andrew

123

Near edge x-ray spectroscopy theory. Annual progress report, 1993--1994  

SciTech Connect

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.

Not Available

1994-03-01

124

Fast CCD camera for x-ray photon correlation spectroscopy and time-resolved x-ray scattering and imaging  

NASA Astrophysics Data System (ADS)

A new, fast x-ray detector system is presented for high-throughput, high-sensitivity, time-resolved, x-ray scattering and imaging experiments, most especially x-ray photon correlation spectroscopy (XPCS). After a review of the architectures of different CCD chips and a critical examination of their suitability for use in a fast x-ray detector, the new detector hardware is described. In brief, its principal component is an inexpensive, commercial camera-the SMD1M60-originally designed for optical applications, and modified for use as a direct-illumination x-ray detector. The remainder of the system consists of two Coreco Imaging PC-DIG frame grabber boards, located inside a Dell Power-edge 6400 server. Each frame grabber sits on its own PCI bus and handles data from 2 of the CCD's 4 taps. The SMD1M60 is based on a fast, frame-transfer, 4-tap CCD chip, read out at12-bit resolution at frame rates of up to 62 Hz for full frame readout and up to 500 Hz for one-sixteenth frame readout. Experiments to characterize the camera's suitability for XPCS and small-angle x-ray scattering (SAXS) are presented. These experiments show that single photon events are readily identified, and localized to within a pixel index or so. This is a sufficiently fine spatial resolution to maintain the speckle contrast at an acceptable value for XPCS measurements. The detective quantum efficiency of the SMD1M60 is 49% for directly-detected 6.3 keV x rays. The effects of data acquisition strategies that permit near-real-time data compression are also determined and discussed. Overall, the SMD1M60 detector system represents a major improvement in the technology for time-resolved x-ray experiments, that require an area detector with time-resolutions in few-milliseconds-to-few-seconds range, and it should have wide applications, extending beyond XPCS.

Falus, P.; Borthwick, M. A.; Mochrie, S. G. J.

2004-11-01

125

TES-based microcalorimeter for future X-ray astronomy missions. Software development for instrument calibration  

NASA Astrophysics Data System (ADS)

The XMS (X-ray Microcalorimeter Spectrometer) is an instrument prototype with imaging capability in X-rays and high-spectral resolution. This instrument is a microcalorimeter based on transition edge sensors. As part of the Spanish contribution to the advancement of the XMS, we present the work carried out by the X-ray astronomy group at the Instituto de Física de Cantabria in collaboration with The Netherlands Institute for Space Research. The main work hereby presented includes the development and testing of software for this prototype with the purpose of instrument calibration and characterization, X-ray pulse detection and energy resolution calculations (Bergmann 2004, Tekst. Proefschrift Universiteit Utrecht; Boyce et al. 1999, Proc SPIE 3765; Den Herder et al. 2011, SRON-XMS-RP-2011-033; ATHENA Assessment Study Report, ESA/SRE(2011)17)

Fraga-Encinas, R.; Cobo, B.; Ceballos, M.; Schuurmans, J.; van der Kuur, J.; Carrera, F.; Barcons, X.

2013-05-01

126

Detection limits for actinides in a monochromatic, wavelength-dispersive x-ray fluorescence instrument  

SciTech Connect

Recent developments in x-ray optics have made it possible to examine the L x-rays of actinides using doubly-curved crystals in a bench-top device. A doubly-curved crystal (DCC) acts as a focusing monochromatic filter for polychromatic x-rays. A Monochromatic, Wavelength-Dispersive X-Ray Fluorescence (MWDXRF) instrument that uses DCCs to measure Cm and Pu in reprocessing plant liquors was proposed in 2007 by the authors at Los Alamos National Laboratory. A prototype design of this MWDXRF instrument was developed in collaboration with X-ray Optical Systems Inc. (XOS), of East Greenbush, New York. In the MWDXRF instrument, x-rays from a Rhodium-anode x-ray tube are passed through a primary DCC to produce a monochromatic beam of 20.2-keV photons. This beam is focused on a specimen that may contain actinides. The 20.2-keV interrogating beam is just above the L3 edge of Californium; each actinide (with Z = 90 to 98) present in the specimen emits characteristic L x-rays as the result of L3-shell vacancies. In the LANL-XOS prototype MWDXRf, these x-rays enter a secondary DCC optic that preferentially passes 14.961-keV photons, corresponding to the L-alpha-1 x-ray peak of Curium. In the present stage of experimentation, Curium-bearing specimens have not been analyzed with the prototype MWDXRF instrument. Surrogate materials for Curium include Rubidium, which has a K-beta-l x-ray at 14.961 keV, and Yttrium, which has a K-alpha-1 x-ray at 14.958 keV. In this paper, the lower limit of detection for Curium in the LANL-XOS prototype MWDXRF instrument is estimated. The basis for this estimate is described, including a description of computational models and benchmarking techniques used. Detection limits for other actinides are considered, as well as future safeguards applications for MWDXRF instrumentation.

Collins, Michael L [Los Alamos National Laboratory; Havrilla, George J [Los Alamos National Laboratory

2009-01-01

127

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  

SciTech Connect

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 ? 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.

Brown, Matthew A.; Redondo, Amaia Beloqui; Duyckaerts, Nicolas; Mächler, Jean-Pierre [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland)] [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)] [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)] [Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland); Bokhoven, Jeroen A. van [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland) [Institute for Chemical and Bioengineering, ETH Zürich, CH-8093 Zürich (Switzerland); Paul Scherrer Institute, CH-5232 Villigen PSI (Switzerland)

2013-07-15

128

Performance characterization of hard x-ray imaging instruments at synchrotron radiation facility SPring-8  

NASA Astrophysics Data System (ADS)

The relevance of pre-flight calibration of space-born instruments is widely recognized. As an energy region of interest shifts to hard X-rays in these years, measurement setup becomes difficult to be afforded or maintained by a laboratory- or small-collaboration-based resources. In 10 to 100 KeV region X-ray source that is bright and monochromatic enough to calibrate optics in detail is no longer available other than at synchrotron facilities. Focal length becomes longer and this is another aspect that is beyond capabilities of soft-X-ray-oriented facilities. The hard X-ray instruments for balloon program have been characterized at synchrotron facility SPring-8/BL20B2 in Japan. SPring-8 is one of the world's brightest third generation synchrotron radiation facilities. BL20B2 is specialized for medical and imaging experiment, and has 200m-long transport tube. Measurement at BL20B2 has great advantages such as extremely high flux, large sized and less divergent beam, and monochromatic beam covering entire hard X-ray region from 8 to 12keV. 16m-long experiment hutch is capable of long focal length of hard-X-ray telescope. Pt/C multilayer-supermirror hard X-ray telescopes, position-sensitive scintillation counter and scintillator-deposited CCD, have been characterized at the facility. Insttrumentation of the facility and some of measurement results are presented.

Ogasaka, Yasushi; Tamura, Keisuke; Shibata, Ryo; Furuzawa, Akihiro; Nakamura, Tomokazu; Naitou, Masataka; Miyazawa, Takuya; Shimoda, Kenta; Onishi, Katsuhiko; Fukaya, Yoshihiro; Iwahara, Tomonaga; Kanou, Yasushi; Kunieda, Hideyo; Yamashita, Koujun; Miyata, Emi; Mukai, Kenji; Ikegami, Kazuhiro; Aono, Michihiko; Tsunemi, Hiroshi; Uesugi, Kentaro; Suzuki, Yoshio

2006-07-01

129

X-ray spectroscopy in the EC nucleus  

NASA Astrophysics Data System (ADS)

The probabilities PKK of double K-shell vacancy production per K electron capture decay and per K internal conversion of 109Cd and 207Bi have been determined by means of the double- and triple-coincidence experiments using K? X-ray and K internal conversion. For 109Cd we find PKK(EC) = (4.2 ± 0.5) × 10 -5 and PKK(IC) = (4.32 ± 0.46) × 10 -5, and for 207Bi, PKK(EC) = (2.54 ± 0.50) × 10 -5. The observed X-ray energy shifts of the hypersatellite Ag ( K?1H) X-ray and the hypersatellite Pb ( K?1H) X-ray lines are 545±15 eV and 1238±45 eV, respectively.

Ko, Seung Kook; Cho, Hyun Jae; Nha, Sang Kyun

1998-10-01

130

Development of a Novel Instrument for X-Ray Photoelectron Diffraction and Holography  

Microsoft Academic Search

For X-ray photoelectron diffraction (XPED) and holography measurements we developed a novel laboratory instrument with the multienergy high power X-ray source and the high energy and high angular resolution photoelectron spectrometer system. The photon intensities of Al Kalpha, Cr Lalpha and Cu Kalpha were estimated at 4.6 × 1011 cps, 7.5 × 1010 cps and 7.2 × 1010 cps, respectively.

Hideshi Ishii; Susumu Shiraki; Keiji Tamura; Wei-Guo Chu; Masanori Owari; Ryuichi Shimizu; Yoshimasa Nihei

2003-01-01

131

Instrumentation advances and detector development with the Stony Brook scanning transmission X-ray microscope  

Microsoft Academic Search

Driven by the requirements of new x-ray microscopy instrumentation the Stony Brook microscopy beamline X-1A has undergone considerable evolution [1]. The room temperature scanning transmission X-ray microscope (STXM) has been completely redesigned improving performance, case of use and compatibility with other experiments. We present the highlights of the new design, the available detectors and the result of early tests of

M. Feser; T. Beetz; M. Carlucci-Dayton; C. Jacobsen

2000-01-01

132

Probing YSOs with Hard X-Ray Imaging and Spectroscopy  

Microsoft Academic Search

This paper surveys the past, present and future prospect on hard X-ray studies of star forming regions. The report is concentrated on the Japanese activities of the hard X-ray emission from Young Stellar Objects (YSOs) deeply embedded in star forming gas clouds. The non-imaging satellites Tenma and Ginga firstly found variable and high temperature plasma from a star forming dark

K. Koyama

1999-01-01

133

X-ray spectroscopy of five BL Lacertae objects  

NASA Technical Reports Server (NTRS)

Five X-ray bright BL Lacertae objects were observed in the energy range 0.6-4.5 keV with the solid state spectrometer (SSS) of the Einstein Observatory. The 14 SSS spectra obtained represent most of the X-ray spectra of BL Lac objects with resolution better than approximately 3. These data do not reveal the presence of large amounts of thermal gas, with upper limits for the equivalent width of individual spectral features typically less that about 100 eV. However, the SSS spectra are the first set of X-ray data to indicate low-energy absorption in excess of that caused by the cold interstellar matter in the Galaxy. Comparison with contemporaneous, lower energy X-ray data implies that this absorption does not arise in cold neutral material, but in hotter, highly ionized material, probably intrinsic to the source. All five BL Lac objects have X-ray continua that are well fitted by power-law models, with power-law energy indices usually greater than about 1. In a few cases, a flattening at higher energies is observed; these and other data suggest that two-component X-ray spectra, steep at low energies and flat at high energies, are a common feature of BL Lac objects. Three of the five sources clearly vary between SSS observations, with time scales ranging from days to years. A historical synopsis of the X-ray spectral data confirms the tendency for BL Lacertae objects to be highly variable in the X-ray band but reveals no correlation between spectral and intensity changes.

Urry, C. M.; Mushotzky, R. F.; Holt, S. S.

1986-01-01

134

CdZnTe detector in mammographic x-ray spectroscopy  

Microsoft Academic Search

A CdZnTe (CZT) detector was utilized in mammographic x-ray spectroscopy under clinical conditions. First, the detector response was investigated using gamma-rays from 241Am. The escape of secondary (Compton scattered and K fluorescent) x-rays and tailing due to carrier trapping were minor in the mammographic energy range. In addition, the transmission of primary x-rays was minimal from the results calculated using

Satoshi Miyajima; Kotaro Imagawa

2002-01-01

135

Novel Approaches to Soft X-ray Spectroscopy: Scanning TransmissionX-ray Microscopy and Ambient Pressure X-Ray PhotoelectronSpectroscopy  

SciTech Connect

This workshop focused on novel spectroscopies at Beamlines 11.0.2, 5.3.2 and 9.3.2 at the ALS. The workshop brought together users from a wide range of fields to highlight recent experimental and technical developments both in scanning transmission X-ray spectroscopy (STXM) and ambient pressure photoelectron spectroscopy (APPES). The morning session featured talks on experiments involving new developments at the STXM, while the afternoon session was devoted to those using APXPS. In the morning session, Tolek Tyliszczak discussed the improved detector developments at the STXM, such as an avalanche photodiode detector and fluorescence and electron detection, as well as the continued development of in situ cells for heating, gas flow, and electrochemical cells. Of these, only the avalanche photodiode in combination with a novel multichannel photon-counting system is in routine use in time-resolved studies. Bartel Van Waeyenberge (Ghent University) presented results of magnetic imaging with a time resolution of 70-100 ps combined with a lateral resolution of 20-40 nm performed with the STXM (Beamline 11.0.2). As a complement to the time-domain ''pump-and-probe'' measurements, they developed a frequency-domain ''sine-excitation'' technique in order to study specific eigenmodes of these ferromagnetic patterns with high spatial resolution. This new approach was used to study the gyrotropic vortex motions in micron-sized ferromagnetic patterns. Adam Hitchcock (McMaster University) presented the development, in collaboration with Daniel Guay (INRS, Varennes) and Sherry Zhang, of the apparatus and techniques for applying STXM to in-situ studies of electrochemistry, in particular electrochromism in polyaniline. In addition, substantial progress was reported on a joint project to develop substrates and methods for chemically selective lithography of multilayer polymer systems. Selective patterns, such as that displayed in the figure, can now be written efficiently with the bend magnet STXM on Beamline 5.3.2. Yves Acremann (SSRL) discussed time and spatially resolved X-ray magnetic circular dichroism (XMCD) experiments on spin transfer devices at the STXM (Beamline 11.0.2). These elegant experiments explore time resolved measurements of the magnetization dynamics within a 100 x 150 nm sample influenced by a spin-polarized current. This experiment shows that the magnetization in these magnetic nanostructures are not uniform, as they are influenced by the Oersted field of the charge current needed to generate the spin current. The implementation of a novel multichannel photon counting system in combination with an avalanche photon detector decreased the data-acquisition time by a factor of 10, owing to its ability to resolve the structure of multi bunch mode. Gordon E. Brown, Jr. (Stanford University and SSRL) described ''Applications of STXM to Microbial Bioweathering and Biomineralization''. In the interaction of bacteria with ferrihydrite nanoparticles, microenvironments that were very different than the bulk material were observed, showing that bulk thermodynamics may not be useful for predicting micro phases. Gordon also presented work showing that iron nanoparticles are attracted to the negatively charged bacteria and form a coating that reduces iron oxide minerals. The afternoon session started with presentations by Simon Mun and Hendrik Bluhm, who discussed the current status and the future plans for the two APPES end-stations at the ALS, which are located at Beamlines 9.3.2 and 11.0.2, respectively. In both end-stations, samples can be measured in gaseous environments at pressures of up to several Torr, which makes possible the investigation of numerous phenomena, in particular in the fields of atmospheric and environmental science as well as heterogeneous catalysis. Specific examples of the application of APPES were shown in the following presentations. John Hemminger (University of California, Irvine) reported on APPES investigations at Beamlines 9.3.2 and 11.0.2 of the interaction of alkali halide surfaces with water. The m

Bluhm, Hendrik; Gilles, Mary K.; Mun, Simon B.; Tyliszczak, Tolek

2006-02-01

136

Instrument for x-ray magnetic circular dichroism measurements at high pressures  

SciTech Connect

An instrument has been developed for x-ray magnetic circular dichroism (XMCD) measurements at high pressures and low temperatures. This instrument couples a nonmagnetic copper-beryllium diamond anvil cell featuring perforated diamonds with a helium flow cryostat and an electromagnet. The applied pressure can be controlled in situ using a gas membrane and calibrated using Cu K-edge x-ray absorption fine structure measurements. The performance of this instrument was tested by measuring the XMCD spectra of the Gd{sub 5}Si{sub 2}Ge{sub 2} giant magnetocaloric material.

Haskel, D.; Tseng, Y. C.; Lang, J. C.; Sinogeikin, S. [Magnetic Materials Group, Advanced Photon Source, Argonne National Laboratory, Argonne, lllinois 60439 (United States); HPCAT, Carnegie Institution of Washington, Advanced Photon Source, Argonne National Laboratory, Argonne, lllinois 60439 (United States)

2007-08-15

137

A novel instrument for quantitative nanoanalytics involving complementary X-ray methodologies  

SciTech Connect

A novel ultra-high vacuum instrument for X-ray reflectometry and spectrometry-related techniques for nanoanalytics by means of synchrotron radiation has been constructed and commissioned. This versatile instrument was developed by the Physikalisch-Technische Bundesanstalt, Germany's national metrology institute, and includes a 9-axis manipulator that allows for an independent alignment of the samples with respect to all degrees of freedom. In addition, a rotational and translational movement of several photodiodes as well as a translational movement of an aperture system in and out of the beam is provided. Thus, the new instrument enables various analytical techniques based on energy dispersive X-ray detectors such as reference-free X-ray fluorescence analysis (XRF), total-reflection XRF, grazing-incidence XRF in addition to optional X-ray reflectometry measurements or polarization-dependent X-ray absorption fine structure analyses. With this instrument samples having a size of up to 100 mm Multiplication-Sign 100 mm can be analyzed with respect to their mass deposition, elemental or spatial composition, or the species in order to probe surface contamination, layer composition and thickness, the depth profile of matrix elements or implants, the species of nanolayers, nanoparticles or buried interfaces as well as the molecular orientation of bonds. Selected applications of this advanced ultra-high vacuum instrument demonstrate both its flexibility and capability.

Lubeck, J.; Beckhoff, B.; Fliegauf, R.; Holfelder, I.; Hoenicke, P.; Mueller, M.; Pollakowski, B.; Reinhardt, F.; Weser, J. [Physikalisch-Technische Bundesanstalt, Abbestr. 2-12, 10587 Berlin (Germany)

2013-04-15

138

EBIT x ray spectroscopy studies for applications to photo-pumped x ray lasers  

NASA Astrophysics Data System (ADS)

Several pumping mechanisms have been suggested for x-ray lasers including collisional excitation, recombination, photo-ionization and photo-pumping. The success of photo-pumping as an x-ray laser scheme hinges on sufficient overlap of the emission and adsorption lines. For such a scheme to exhibit gain, the difference of the energies of the two lines must be within the line widths determined by the plasma dynamics, such as Doppler and opacity broadening. Typically, an overlap of a few parts in 10(exp 4) is required. Due to correlation effects, high-n levels of multi-electron ions are difficult to calculate and are reliable to roughly a part in 10(exp 3). These differences are large enough to preclude accurate predictions of successful overlaps. As a result, precise measurements of the overlaps are needed. The continued interest in photo-pumping schemes lies in its potential to improve the laser output. It also allows the excitation of lasing transitions not accessible to other mechanisms and thus to the test laser kinetics from a different perspective. We have studied several such photo-pumping schemes at the LLNL electron beam ion trap. The N-like isoelectronic sequence 3d-5f and 3d-6f transitions were studied for photo-pumping by He-like ions, the Ne-like 2p-4d transitions were studied for photo-pumping by N-like 3d-4f transitions, and Ni-like 3d(sub 5/2)-6f(sub 7/2) transitions were studied for photo-pumping by H-like Ly-alpha transitions. A number of other chance coincidence pairs which do not follow an isoelectronic sequence were also studied. The data were taken with a flat-crystal vacuum spectrometer, a flat-crystal helium atmosphere spectrometer, or a curved-crystal spectrometer in the von Hamos geometry. The advantage of EBIT over laser-produced or tokamak plasmas for such experiments is its ability to control the charge balance and the excitation process. By choosing the electron beam energy, we can select a dominant charge state.

Elliott, S. R.; Beiersdorfer, P.; Nilsen, J.

1994-05-01

139

EBIT x-ray spectroscopy studies for applications to photo-pumped x-ray lasers  

SciTech Connect

Several pumping mechanisms have been suggested for x-ray lasers including collisional excitation, recombination, photo-ionization and photo-pumping. The success of photo-pumping as an x-ray laser scheme hinges on sufficient overlap of the emission and adsorption lines. For such a scheme to exhibit gain, the difference of the energies of the two lines must be within the line widths determined by the plasma dynamics, such as Doppler and opacity broadening. Typically, an overlap of a few parts in 10{sup 4} is required. Due to correlation effects, high-n levels of multi-electron ions are difficult to calculate and are reliable to roughly a part in 10{sup 3}. These differences are large enough to preclude accurate predictions of successful overlaps. As a result, precise measurements of the overlaps are needed. The continued interest in photo-pumping schemes lies in its potential to improve the laser output. It also allows the excitation of lasing transitions not accessible to other mechanisms and thus to the test laser kinetics from a different perspective. We have studied several such photo-pumping schemes at the LLNL electron beam ion trap. The N-like isoelectronic sequence 3d-5f and 3d-6f transitions were studied for photo-pumping by He-like ions, the Ne-like 2p-4d transitions were studied for photo-pumping by N-like 3d-4f transitions, and Ni-like 3d{sub 5/2}-6f{sub 7/2} transitions were studied for photo-pumping by H-like Ly-{alpha} transitions. A number of other chance coincidence pairs which do not follow an isoelectronic sequence were also studied. The data were taken with a flat-crystal vacuum spectrometer, a flat-crystal helium atmosphere spectrometer, or a curved-crystal spectrometer in the von Hamos geometry. The advantage of EBIT over laser-produced or tokamak plasmas for such experiments is its ability to control the charge balance and the excitation process. By choosing the electron beam energy, we can select a dominant charge state.

Elliott, S.R.; Beiersdorfer, P.; Nilsen, J.

1994-05-10

140

EUV, X-ray, and gamma-ray instrumentation for astronomy and atomic physics; Proceedings of the Meeting, San Diego, CA, Aug. 7-11, 1989  

NASA Astrophysics Data System (ADS)

Topics discussed in this volume include hard X-ray and gamma-ray imaging techniques, hard X-ray and gamma-ray spectroscopic and imaging detectors, X-ray/EUV solid-state imagers, balloon and spaceborne experiments and missions, laboratory atomic physics instrumentation, and proportional counter detectors. Other topics discussed are high-resolution X-ray spectrometers, detector calibration, position readout techniques, and X-ray/EUV optics for astronomy and microscopy. Papers are presented on a Monte Carlo simulation of gamma-ray detectors using scintillation fibers, high-pressure gas scintillation drift chambers with wave-shifter readout, the X-ray characteristics of CCDs for the XMM reflection grating spectrometer, the in-flight performance of the hard X-ray telescope MIFRASO, and two wireless imaging proportional counters. Also considered are a fiber-fed imaging spectrometer, high-resolution X-ray spectroscopy using germanium microcalorimeters, and designs of scattering polarimeters at the focus of an X-ray telescope.

Hailey, Charles J.; Siegmund, Oswald H. W.

1989-11-01

141

Double conical crystal x-ray spectrometer for high resolution ultrafast x-ray absorption near-edge spectroscopy of Al K edge  

SciTech Connect

An x-ray spectrometer devoted to dynamical studies of transient systems using the x-ray absorption fine spectroscopy technique is presented in this article. Using an ultrafast laser-induced x-ray source, this optical device based on a set of two potassium acid phthalate conical crystals allows the extraction of x-ray absorption near-edge spectroscopy structures following the Al absorption K edge. The proposed experimental protocol leads to a measurement of the absorption spectra free from any crystal reflectivity defaults and shot-to-shot x-ray spectral fluctuation. According to the detailed analysis of the experimental results, a spectral resolution of 0.7 eV rms and relative fluctuation lower than 1% rms are achieved, demonstrated to be limited by the statistics of photon counting on the x-ray detector.

Levy, A.; Dorchies, F.; Fourment, C.; Harmand, M.; Hulin, S.; Santos, J. J.; Descamps, D.; Petit, S.; Bouillaud, R. [Centre Lasers Intenses et Applications (CELIA), Universite de Bordeaux-CNRS-CEA, Talence F-33405 (France)

2010-06-15

142

Double conical crystal x-ray spectrometer for high resolution ultrafast x-ray absorption near-edge spectroscopy of Al K edge  

NASA Astrophysics Data System (ADS)

An x-ray spectrometer devoted to dynamical studies of transient systems using the x-ray absorption fine spectroscopy technique is presented in this article. Using an ultrafast laser-induced x-ray source, this optical device based on a set of two potassium acid phthalate conical crystals allows the extraction of x-ray absorption near-edge spectroscopy structures following the Al absorption K edge. The proposed experimental protocol leads to a measurement of the absorption spectra free from any crystal reflectivity defaults and shot-to-shot x-ray spectral fluctuation. According to the detailed analysis of the experimental results, a spectral resolution of 0.7 eV rms and relative fluctuation lower than 1% rms are achieved, demonstrated to be limited by the statistics of photon counting on the x-ray detector.

Levy, A.; Dorchies, F.; Fourment, C.; Harmand, M.; Hulin, S.; Santos, J. J.; Descamps, D.; Petit, S.; Bouillaud, R.

2010-06-01

143

Ultraviolet Spectroscopy of the X-ray Transient CI Cam  

NASA Astrophysics Data System (ADS)

The transient X-ray source XTE J0421+560 erupted on 1998 March 31. Transient X-ray sources are all binary stars that contain an accreting neutron star or black hole, but the XTE J0421+560 binary system is unusual and possibly unique. It emitted strong, non-thermal radio flux during its eruption and possibly ejected a pair of relativistic jets. The eruption decayed in a few days, more rapidly than most X-ray transients. CI Cam, the optical counterpart of XTE J0421+560, is the brightest known X-ray transient, allowing high- resolution measurements of its spectrum. Its optical and near- infrared spectrum is dominated by strong emission lines, with remarkably strong Fe II emission. The spectrum shows that there is a complex circumstellar environment containing at least two or possibly three kinematically and thermally distinct shells. There is also a high velocity wind, which may have been produced during the outburst. We will obtain the first ultraviolet spectrum of CI Cam. Using the MAMA echelle gratings we will measure: the ultraviolet continuum, the reddening, the line profiles, and the Fe II emission line ratios. From these data will determine whether the system is a high-- or low--mass X-ray binary, the wind structure, the physical conditions in the shells and the accretion flow, and the cause of the anomalously strong Fe II emission.

Robinson, Edward

1999-07-01

144

Centaurus X-3. [early x-ray binary star spectroscopy  

NASA Technical Reports Server (NTRS)

Spectroscopic observations of Krzeminski's star at dispersions 25-60 A/mm are described. The primary is an evolved star of type O6-O8(f) with peculiarities, some of which are attributable to X-ray heating. Broad emission lines at 4640A (N III), 4686 A(He II) and H-alpha show self-absorption and do not originate entirely from the region near the X-ray star. The primary is not highly luminous (bolometric magnitude about -9) and does not show signs of an abnormally strong stellar wind. The X-ray source was 'on' at the time of optical observations. Orbital parameters are presented for the primary, which yield masses of 17 + or - 2 and 1.0 + or - 3 solar masses for the stars. The optical star is undermassive for its luminosity, as are other OB-star X-ray primaries. The rotation is probably synchronized with the orbital motion. The distance to Cen X-3 is estimated to be 10 + or - 1 kpc. Basic data for 12 early-type X-ray primaries are discussed briefly

Hutchings, J. B.; Cowley, A. P.; Crampton, D.; Van Paradus, J.; White, N. E.

1979-01-01

145

Probing electronic structure and chemical bonding with x-ray spectroscopy  

Microsoft Academic Search

The availability of synchrotron sources has expanded significantly the use of x-ray photoelectron (PE) and photoabsorption (PA) spectroscopy to probe the molecular electronic structure and to test the various bonding models the understanding of which is central to all aspects of chemistry. All features observed in x-ray spectra result from electronic transitions within the molecule, which are in turn determined

Astrid Jurgensen

1999-01-01

146

Ultrafast Conversions Between Hydrogen Bonded Structures in Liquid Water Observed by Femtosecond X-Ray Spectroscopy.  

National Technical Information Service (NTIS)

We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray ...

A. M. Lindenberg H. Wen N. Huse R. W. Schoenlein

2010-01-01

147

Real-time Quantitative X-Ray Spectroscopy with a von Hamos Spectrometer  

NASA Astrophysics Data System (ADS)

The real-time quantitative spectroscopy of laser-produced plasmas is explored using a compact von Hamos spectrometer and linear CCD array. This system provides excellent spectral resolution and high dynamic range for compact x-ray sources. Possible uses of this spectrometer include applications in x-ray lithography and laser produced plasma diagnostics.

Weeks, Tyler; Johnson, Michael; Raymond, Scott; Johnson, Jon Paul; Knight, Larry; Shevelko, Alexander

2004-10-01

148

Evolutionary developments in x ray and electron energy loss microanalysis instrumentation for the analytical electron microscope  

NASA Astrophysics Data System (ADS)

Developments in instrumentation for both X ray Dispersive and Electron Energy Loss Spectroscopy (XEDS/EELS) over the last ten years have given the experimentalist a greatly enhanced set of analytical tools for characterization. Microanalysts have waited for nearly two decades now in the hope of getting a true analytical microscope and the development of 300 to 400 kV instruments should have allowed us to attain this goal. Unfortunately, this has not generally been the case. While there have been some major improvements in the techniques, there has also been some devolution in the modern AEM (Analytical Electron Microscope). In XEDS, the majority of today's instruments are still plagued by the hole count effect, which was first described in detail over fifteen years ago. The magnitude of this problem can still reach the 20 percent level for medium atomic number species in a conventional off-the-shelf intermediate voltage AEM. This is an absurd situation and the manufacturers should be severely criticized. Part of the blame, however, also rests on the AEM community for not having come up with a universally agreed upon standard test procedure. Fortunately, such a test procedure is in the early stages of refinement. The proposed test specimen consists of an evaporated Cr film approx. 500 to 1000A thick supported upon a 3mm diameter Molybdenum 200 micron aperture.

Zaluzec, Nester J.

149

A whole-system approach to x-ray spectroscopy in cargo inspection systems  

SciTech Connect

The bremsstrahlung x-ray spectrum used in high-energy, high-intensity x-ray cargo inspection systems is attenuated and modified by the materials in the cargo in a Z-dependent way. Therefore, spectroscopy of the detected x rays yields information about the Z of the x-rayed cargo material. It has previously been shown that such ZSpectroscopy (Z-SPEC) is possible under certain circumstances. A statistical approach, Z-SCAN (Z-determination by Statistical Count-rate ANalysis), has also been shown to be effective, and it can be used either by itself or in conjunction with Z-SPEC when the x-ray count rate is too high for individual x-ray spectroscopy. Both techniques require fast x-ray detectors and fast digitization electronics. It is desirable (and possible) to combine all techniques, including x-ray imaging of the cargo, in a single detector array, to reduce costs, weight, and overall complexity. In this paper, we take a whole-system approach to x-ray spectroscopy in x-ray cargo inspection systems, and show how the various parts interact with one another. Faster detectors and read-out electronics are beneficial for both techniques. A higher duty-factor x-ray source allows lower instantaneous count rates at the same overall x-ray intensity, improving the range of applicability of Z-SPEC in particular. Using an intensity-modulated advanced x-ray source (IMAXS) allows reducing the x-ray count rate for cargoes with higher transmission, and a stacked-detector approach may help material discrimination for the lowest attenuations. Image processing and segmentation allow derivation of results for entire objects, and subtraction of backgrounds. We discuss R and D performed under a number of different programs, showing progress made in each of the interacting subsystems. We discuss results of studies into faster scintillation detectors, including ZnO, BaF{sub 2} and PbWO{sub 4}, as well as suitable photo-detectors, read-out and digitization electronics. We discuss high-duty-factor linear-accelerator x-ray sources and their associated requirements, and how such sources improve spectroscopic techniques. We further discuss how image processing techniques help in correcting for backgrounds and overlapping materials. In sum, we present an integrated picture of how to optimize a cargo inspection system for x-ray spectroscopy.

Langeveld, Willem G. J.; Gozani, Tsahi; Ryge, Peter; Sinha, Shrabani; Shaw, Tim; Strellis, Dan [Rapiscan Laboratories, Inc. 520 Almanor Ave. Sunnyvale, CA 94085 (United States)

2013-04-19

150

Observation of chemical shifts of Si 2p level by an x-ray photoelectron spectroscopy system with a laser-plasma x-ray source  

Microsoft Academic Search

An x-ray photoelectron spectroscopy system with a laser-plasma x-ray source is shown to have energy resolution high enough to observe chemical shifts of Si 2p electrons in SiO2, Si3N4, and pure Si. A boron nitride (BN) plasma x-ray source is produced by irradiation of 100 mJ Q-switched YAG laser pulses. A single line emission at 4.86 nm is selected from

Hiroyuki Kondo; Toshihisa Tomie; Hideaki Shimizu

1998-01-01

151

Investigation of the interfacial structure of ultra-thin platinum films using X-ray reflectivity and X-ray photoelectron spectroscopy  

Microsoft Academic Search

Ultra-thin films of platinum deposited on highly polished 100 silicon have been investigated using X-ray reflectivity (XRR) and X-ray photoelectron spectroscopy (XPS) as part of a study on the interface structure of multilayers used for X-ray mirrors. In this paper results are presented for films deposited by electron beam evaporation and by DC-magnetron sputtering. The reflectivity was fitted by assuming

D. M Solina; R. W Cheary; P. D Swift; S Dligatch; G. M McCredie; B Gong; P Lynch

2000-01-01

152

An instrument for 3D x-ray nano-imaging  

SciTech Connect

We present an instrument dedicated to 3D scanning x-ray microscopy, allowing a sample to be precisely scanned through a beam while the angle of x-ray incidence can be changed. The position of the sample is controlled with respect to the beam-defining optics by laser interferometry. The instrument achieves a position stability better than 10 nm standard deviation. The instrument performance is assessed using scanning x-ray diffraction microscopy and we demonstrate a resolution of 18 nm in 2D imaging of a lithographic test pattern while the beam was defined by a pinhole of 3 {mu}m in diameter. In 3D on a test object of copper interconnects of a microprocessor, a resolution of 53 nm is achieved.

Holler, M.; Raabe, J.; Diaz, A.; Guizar-Sicairos, M.; Quitmann, C.; Menzel, A.; Bunk, O. [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland)

2012-07-15

153

X-ray spectroscopy in the EC nucleus  

Microsoft Academic Search

The probabilities PKK of double K-shell vacancy production per K electron capture decay and per K internal conversion of 109Cd and 207Bi have been determined by means of the double- and triple-coincidence experiments using Kalpha X-ray and K internal conversion. For 109Cd we find PKK(EC) = (4.2+\\/-0.5)x10-5 and PKK(IC) = (4.32+\\/-0.46)x10-5, and for 207Bi, PKK(EC) = (2.54+\\/-0.50)x10-5. The observed X-ray

Seung Kook Ko; Hyun Jae Cho; Sang Kyun Nha

1998-01-01

154

Doing Solar Science With Extreme-ultraviolet and X-ray High Resolution Imaging Spectroscopy  

NASA Astrophysics Data System (ADS)

In this talk I will demonstrate how high resolution extreme-ultraviolet (EUV) and/or X-ray imaging spectroscopy can be used to provide unique information for solving several current key problems of the solar atmosphere, e.g., the morphology and reconnection site of solar flares, the structure of the transition region, and coronal heating. I will describe the spectra that already exist relevant to these problems and what the shortcomings of the data are, and how an instrument such as the Extreme-ultraviolet Imaging Spectrometer (EIS) on Solar-B as well as other proposed spectroscopy missions such as NEXUS and RAM will improve on the existing observations. I will discuss a few particularly interesting properties of the spectra and atomic data for highly ionized atoms that are important for the science problems.

Doschek, G. A.

2005-12-01

155

Electronic structure of hydrogenated amorphous silicon-germanium alloys studied by X-ray photoelectron spectroscopy and soft-X-ray spectroscopy  

Microsoft Academic Search

The authors present a study of Si 2p and Ge 3d core levels and of the valence Si 3p and conduction Si p and Ge s,d states by, respectively, X-ray-induced photoelectron spectroscopy and soft X-ray emission and absorption spectroscopy, for hydrogenated amorphous silicon-germanium a-Si1-xGex:H alloys with 0.16

C. Senemaud; I. Ardelean

1990-01-01

156

New Homogeneous Standards by Atomic Layer Deposition for Synchrotron X-ray Fluorescence and Absorption Spectroscopies.  

SciTech Connect

Quantification of synchrotron XRF analyses is typically done through comparisons with measurements on the NIST SRM 1832/1833 thin film standards. Unfortunately, these standards are inhomogeneous on small scales at the tens of percent level. We are synthesizing new homogeneous multilayer standards using the Atomic Layer Deposition technique and characterizing them using multiple analytical methods, including ellipsometry, Rutherford Back Scattering at Evans Analytical, Synchrotron X-ray Fluorescence (SXRF) at Advanced Photon Source (APS) Beamline 13-ID, Synchrotron X-ray Absorption Spectroscopy (XAS) at Advanced Light Source (ALS) Beamlines 11.0.2 and 5.3.2.1 and by electron microscopy techniques. Our motivation for developing much-needed cross-calibration of synchrotron techniques is borne from coordinated analyses of particles captured in the aerogel of the NASA Stardust Interstellar Dust Collector (SIDC). The Stardust Interstellar Dust Preliminary Examination (ISPE) team have characterized three sub-nanogram, {approx}1{micro}m-sized fragments considered as candidates to be the first contemporary interstellar dust ever collected, based on their chemistries and trajectories. The candidates were analyzed in small wedges of aerogel in which they were extracted from the larger collector, using high sensitivity, high spatial resolution >3 keV synchrotron x-ray fluorescence spectroscopy (SXRF) and <2 keV synchrotron x-ray transmission microscopy (STXM) during Stardust ISPE. The ISPE synchrotron techniques have complementary capabilities. Hard X-ray SXRF is sensitive to sub-fg mass of elements Z {ge} 20 (calcium) and has a spatial resolution as low as 90nm. X-ray Diffraction data were collected simultaneously with SXRF data. Soft X-ray STXM at ALS beamline 11.0.2 can detect fg-mass of most elements, including cosmochemically important oxygen, magnesium, aluminum and silicon, which are invisible to SXRF in this application. ALS beamline 11.0.2 has spatial resolution better than 25 nm. Limiting factors for Stardust STXM analyses were self-imposed limits of photon dose due to radiation damage concerns, and significant attenuation of <1500 eV X-rays by {approx}80{micro}m thick, {approx}25 mg/cm{sup 3} density silica aerogel capture medium. In practice, the ISPE team characterized the major, light elements using STXM (O, Mg, Al, Si) and the heavier minor and trace elements using SXRF. The two data sets overlapped only with minor Fe and Ni ({approx}1% mass abundance), providing few quantitative cross-checks. New improved standards for cross calibration are essential for consortium-based analyses of Stardust interstellar and cometary particles, IDPs. Indeed, they have far reaching application across the whole synchrotron-based analytical community. We have synthesized three ALD multilayers simultaneously on silicon nitride membranes and silicon and characterized them using RBS (on Si), XRF (on Si{sub 3}N{sub 4}) and STXM/XAS (holey Si{sub 3}N{sub 4}). The systems we have started to work with are Al-Zn-Fe and Y-Mg-Er. We have found these ALD multi-layers to be uniform at {micro}m- to nm scales, and have found excellent consistency between four analytical techniques so far. The ALD films can also be used as a standard for e-beam instruments, eg., TEM EELS or EDX. After some early issues with the consistency of coatings to the back-side of the membrane windows, we are confident to be able to show multi-analytical agreement to within 10%. As the precision improves, we can use the new standards to verify or improve the tabulated cross-sections.

Butterworth, A.L.; Becker, N.; Gainsforth, Z.; Lanzirotti, A.; Newville, M.; Proslier, T.; Stodolna, J.; Sutton, S.; Tyliszczak, T.; Westphal, A.J.; Zasadzinski, J. (UCB)

2012-03-13

157

Corrosion and degradation studies utilizing X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

This dissertation involves studies of corrosion behavior at the surface of various metal samples, as well as the degradation of wool fibers obtained from the Star-Spangled Banner. Molybdenum metal and iron-zinc alloys were examined under corrosive conditions, and the degradation of the wool fibers was studied. The behavior of a polished molybdenum metal surface upon exposure to both aerated and deaerated water and 1.0 M NaCl solution was studied by X-ray Photoelectron Spectroscopy (XPS). Exposure to deaerated water and NaCl failed to produce oxidation of the metal surfaces, but exposing the polished metal surface to aerated water produced significant oxidation. Metal surfaces cleaned by argon-ion etching were found to be inert to oxidation by aerated water. The etching process also appears to passivate the metal surface. The behavior of molybdenum metal in 0.5 M Hsb2SOsb4 treated at various potentials has been studied using core and valence band XPS. The study indicates that Mosp{IV} and Mosp{VI} (including possibly Mosp{V} in some cases) were formed as the potential of the system was increased within the active range of molybdenum. The corrosive behavior of iron-zinc alloys that have been electroplated on plain steel in both aerated and deaerated quadruply-distilled water has been studied using XPS. Several different iron-zinc alloys were electroplated for comparative purposes: an iron-rich alloy, a zinc-rich alloy, and an alloy of similar iron and zinc composition. Treatment in aerated water produces oxidation for the iron-rich and similar composition alloys, but the oxide is reduced for the zinc-rich alloy. Degradation of the fibers in the original Star-Spangled Banner has been monitored using XPS and Scanning Electron Microscopy (SEM). Comparison of white and red wool fibers and linen fibers from the flag with new, mechanically-abraded, and chemically-treated white, red, and linen fibers, respectively, was performed in an attempt to determine the fibers' levels of physical and chemical degradation. Chemical treatment of the fibers gives results similar to those for the fibers from the flag, demonstrating that chemical changes to the fiber surface have occurred over time.

Hixson, Holly Gwyndolen

1997-08-01

158

Si(Li) X-ray astronomical spectroscopy  

NASA Technical Reports Server (NTRS)

The general considerations involved in the choice of Si(Li) as a non-dispersive spectrometer for X-ray astronomy are discussed. In particular, its adaptation to HEAO-B is described as an example of the space-borne application of Si(Li) technology.

Holt, S. S.

1975-01-01

159

Chemically resolved electrical measurements using x-ray photoelectron spectroscopy  

Microsoft Academic Search

Noncontact chemically resolved electrical measurements are presented, capable of probing selected regions within fine heterostructures. Using a slightly modified x-ray photoelectron spectrometer, an effective means is demonstrated for measuring I-V curves of molecular layers, free of substrate and contact contributions. The concept is simple and general, revealing unique details on electrical response mechanisms. Realized with commonly available equipment, it should

Hagai Cohen

2004-01-01

160

ENVIRONMENTAL AND BIOLOGICAL APPLICATIONS OF EXTENDED X-RAY ABSORPTION FINE STRUCTURE (EXAFS) AND X-RAY ABSORPTION NEAR EDGE STRUCTURE (XANES) SPECTROSCOPIES  

Microsoft Academic Search

XAS (X-ray absorption spectroscopy) has proven to be a powerful technique in several fields including the biological and environmental sciences. It has enabled scientists to analyze samples that could not be analyzed using classical techniques such as XRD (X-ray diffraction). In addition, it allows for the direct determination of elemental oxidation states, where the use of other methods is time

J. G. Parsons; M. V. Aldrich; J. L. Gardea-Torresdey

2002-01-01

161

Simulated 'On-Line' Wear Metal Analysis of Lubricating Oils by X-Ray Fluorescence Spectroscopy  

NASA Technical Reports Server (NTRS)

The objective of this project was to assess the sensitivity of X-ray Fluorescence Spectroscopy (XFS) for quantitative evaluation of metal particle content in engine oil suspensions and the feasibility of real-time, dynamic wear metal analysis. The study was focused on iron as the majority wear metal component. Variable parameters were: particle size, particle concentration and oil velocity. A commercial XFS spectrometer equipped with interchangeable static/dynamic (flow cell) sample chambers was used. XFS spectra were recorded for solutions of Fe-organometallic standard and for a series of DTE oil suspensions of high purity spherical iron particles of 2g, 4g, and 8g diameter, at concentrations from 5 ppm to 5,000 ppm. Real contaminated oil samples from Langley Air Force Base aircraft engines and NASA Langley Research Center wind tunnels were also analyzed. The experimental data conform the reliability of XFS as the analytical method of choice for this project. Intrinsic inadequacies of the instrument for precise analytic work at low metal concentrations were identified as being related to the particular x-ray beam definition, system geometry, and flow-cell materials selection. This work supports a proposal for the design, construction and testing of a conceptually new, miniature XFS spectrometer with superior performance, dedicated to on-line, real-time monitoring of lubricating oils in operating engines. Innovative design solutions include focalization of the incident x-ray beam, non-metal sample chamber, and miniaturization of the overall assembly. The instrument would contribute to prevention of catastrophic engine failures. A proposal for two-year funding has been presented to NASA Langley Research Center Internal Operation Group (IOG) Management, to continue the effort begun by this summer's project.

Kelliher, Warren C.; Partos, Richard D.; Nelson, Irina

1996-01-01

162

Sample Preparation of Waste Water to Determine Metallic Contaminants by X-Ray Fluorescence Spectroscopy.  

National Technical Information Service (NTIS)

Trace X-ray fluorescence spectroscopy analysis in liquid samples is preceded by sample preparation, which usually consists in the precipitation of the metallic ions and concentration over a thin cellulose filter. The samples preparation of waste water by ...

J. Gonzalez Olivos

1987-01-01

163

Electrochemical in-situ reaction cell for X-ray scattering, diffraction and spectroscopy  

SciTech Connect

An electrochemical in-situ reaction cell for hard X-ray experiments with battery electrodes is described. Applications include the small angle scattering, diffraction, and near-edge spectroscopy of lithium manganese oxide electrodes.

Braun, Artur; Granlund, Eric; Cairns, Elton J.

2003-01-27

164

The Coherent X-ray Imaging (CXI) Instrument at the Linac Coherent Light Source (LCLS)  

SciTech Connect

The Linac Coherent Light Source (LCLS) has become the first ever operational hard X-ray Free Electron Laser in 2009. It will operate as a user facility capable of delivering unique research opportunities in multiple fields of science. The LCLS and the LCLS Ultrafast Science Instruments (LUSI) construction projects are developing instruments designed to make full use of the capabilities afforded by the LCLS beam. One such instrument is being designed to utilize the LCLS coherent beam to image with high resolution any sub-micron object. This instrument is called the Coherent X-ray Imaging (CXI) instrument. This instrument will provide a flexible optical system capable of tailoring key beam parameters for the users. A suite of shot-to-shot diagnostics will also be provided to characterize the beam on every pulse. The provided instrumentation will include multi-purpose sample environments, sample delivery and a custom detector capable of collecting 2D data at 120 Hz. In this article, the LCLS will be briefly introduced along with the technique of Coherent X-ray Diffractive Imaging (CXDI). A few examples of scientific opportunities using the CXI instrument will be described. Finally, the conceptual layout of the instrument will be presented along with a description of the key requirements for the overall system and specific devices required.

Boutet, Sebastien; Williams, Garth J.; /SLAC; ,

2011-08-16

165

X-ray absorption spectroscopy of vanadium dioxide thin films across the phase-transition boundary  

Microsoft Academic Search

X-ray absorption spectroscopy (XAS) and x-ray photoemission spectroscopy of the V L edge and O K edge were performed on VO2 thin films rf sputtered at various conditions. The spectra give evidence of the changes in the electronic structure depending on the film quality. XAS of the O K edge shows a decrease of the spacing between 3dpi and 3dsigma

Dmitry Ruzmetov; Sanjaya D. Senanayake; Shriram Ramanathan

2007-01-01

166

Science Instruments for the Advanced X-Ray Astrophysics Facility (AXAF)  

NASA Technical Reports Server (NTRS)

The AXAF program has undergone major changes since the Announcement of Opportunity was extended by NASA Headquarters in 1983. The Science Instruments (SI's) for AXAF have also experienced several design changes since they were competitively selected in 1985. Moreover, two separate complementary missions are now being baselined for AXAF; one is designated AXAF-I for imaging and will include the high precision Wolter type I optics, and the other is called AXAF-S for spectroscopy. The resulting less-costly AXAF will still be superior to any previous x-ray observatories. Both missions continue to be managed. AXAF-I contains two focal plane SI's, the High Resolution Camera (HRC), and the AXAF Charge-Coupled Device (CCD) imaging spectrometer (ACIS), as well as the High-Energy Transmission Grating Spectrometer (HETGS) and the Low-Energy Transmission Grating Spectrometer (LETGS). Optics/Cryogenics Division (BECD). AXAF-S features only one focal plane SI, the X-Ray Spectrometer (XRS). The grazing incidence mirrors for this mission are mainly to provide a large collecting area and to concentrate these x-ray photons onto the XRS detector. Precise focusing, although preferred, is of secondary importance. Nested conical foil mirrors are currently baselined; however, replicated imaging optics are being evaluated for collecting efficiency and cost. AXAF-S is scheduled to be launched in late 1999. It has been designated as an MSFC in-house project. In addition to overall management, MSFC is fully responsible for the design, development, integration, and test of the complete AXAF-S observatory, including the XRS which will be furnished by the Goddard Space Flight Center (GSFC). Together, AXAF-I and AXAF-S constitute the third of NASA's series of Great Observatories, joining the Hubble space telescope (HST) and the Gamma-Ray Observatory (GRO) which are already operational. The develop- ment, launch, and operation of the Space InfraRed Telescope Facility (SIRTF) will follow later to complete the Great Observatory series. This paper summarizes the impact these changes have had on the SI's.

Winkler, Carl E.; Cumings, Nesbitt P.; Randolph, Joseph L.; Talley, Drayton H.

1993-01-01

167

X-ray absorption spectroscopy of chicken sulfite oxidase crystals  

SciTech Connect

Sulfite oxidase catalyzes the physiologically vital oxidation of sulfite to sulfate. Recently, the crystal structure of chicken sulfite oxidase has been reported at 1.9 {angstrom} resolution. In contrast to the information available from previous X-ray absorption spectroscopic studies, the active site indicated by crystallography was a mono-oxo species. Because of this the possibility that the crystals did in fact contain a reduced molybdenum species was considered in the crystallographic work. The authors report herein an X-ray absorption spectroscopic study of polycrystalline sulfite oxidase prepared in the same manner as the previous single-crystal samples, and compare this with data for frozen solutions of oxidized and reduced enzyme.

George, G.N.; Pickering, I.J. [Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.] [Stanford Univ., CA (United States). Stanford Synchrotron Radiation Lab.; Kisker, C. [State Univ. of New York, Stony Brook, NY (United States). Dept. of Pharmacological Sciences] [State Univ. of New York, Stony Brook, NY (United States). Dept. of Pharmacological Sciences

1999-05-17

168

X-ray spectroscopy in the EC nucleus  

Microsoft Academic Search

The probabilities PKK of double K-shell vacancy production per K electron capture decay and per K internal conversion of 109Cd and 207Bi have been determined by means of the double- and triple-coincidence experiments using K? X-ray and K internal conversion. For 109Cd we find PKK(EC) = (4.2 ± 0.5) × 10?5 and PKK(IC) = (4.32 ± 0.46) × 10?5, and

Seung Kook Ko; Hyun Jae Cho; Sang Kyun Nha

1998-01-01

169

Time ;;Resolved ;;X-ray ;;Spectroscopy on OMEGA  

Microsoft Academic Search

Soft x-ray spectroscopic diagnostics have been fielded on a plasma generated using 59 beams of the OMEGA laser at LLE, operated at 20 kJ total energy and 1-ns duration. The beams were focused onto neon-filled (10 Atm) microballoon targets of 900-mum diameter, coated with alternating layers of Mg and Al and overcoated with a 1 mum layer of CH. The

R. Elton; E. J. Iglesias; H. R. Griem; S. Goldsmith; J. Delettrez; R. Epstein; G. Pien; D. Bradley

1997-01-01

170

Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy  

NASA Astrophysics Data System (ADS)

I review the current status of X-ray reflection (a.k.a. broad iron line) based black hole spin measurements. This is a powerful technique that allows us to measure robust black hole spins across the mass range, from the stellar-mass black holes in X-ray binaries to the supermassive black holes in active galactic nuclei. After describing the basic assumptions of this approach, I lay out the detailed methodology focusing on "best practices" that have been found necessary to obtain robust results. Reflecting my own biases, this review is slanted towards a discussion of supermassive black hole (SMBH) spin in active galactic nuclei (AGN). Pulling together all of the available XMM-Newton and Suzaku results from the literature that satisfy objective quality control criteria, it is clear that a large fraction of SMBHs are rapidly-spinning, although there are tentative hints of a more slowly spinning population at high (M>5×107 M ?) and low (M<2×106 M ?) mass. I also engage in a brief review of the spins of stellar-mass black holes in X-ray binaries. In general, reflection-based and continuum-fitting based spin measures are in agreement, although there remain two objects (GRO J1655-40 and 4U 1543-475) for which that is not true. I end this review by discussing the exciting frontier of relativistic reverberation, particularly the discovery of broad iron line reverberation in XMM-Newton data for the Seyfert galaxies NGC 4151, NGC 7314 and MCG-5-23-16. As well as confirming the basic paradigm of relativistic disk reflection, this detection of reverberation demonstrates that future large-area X-ray observatories such as LOFT will make tremendous progress in studies of strong gravity using relativistic reverberation in AGN.

Reynolds, Christopher S.

2013-08-01

171

Beam synchronous detection techniques for X-Ray spectroscopy  

NASA Astrophysics Data System (ADS)

The Photo diode detectors combine a set of properties that make them most appropriate, in particular, for X-ray Magnetic Circular Dichroism (XMCD) experiments. Under standard operating conditions, the detection bandwidth is primarily limited by the transimpedance preamplifier that converts the very low ac photocurrent into a voltage. On the other hand, when the photodiode is reverse biased, its finite shunt resistance will cause an undesirable, temperature dependent DC dark current. The best strategy to get rid of it is to use synchronous detection techniques. A classical implementation is based on the use of a chopper modulating the X-ray beam intensity at rather low frequencies (typically below 1 kHz). Here we report on the recent development of a fast Xray detection which has the capability to fully exploit the frequency structure of the ESRF X-ray beam (355 KHz and its harmonics). The availability of new wide band preamplifiers allowed us to extend the working frequency range up to a few MHz. A beam synchronous data processing was implemented in large FPGAs. Performances of the new detection system implemented at the ESRF beamline ID12 are illustrated with detection of the Fe K-edge XMCD spectra in garnets, using 4 bunches operation mode with modulation frequency of 1.4 MHz.

Goujon, Gérard; Rogalev, Andreï; Goulon, José; Feite, Serge; Wilhelm, Fabrice

2013-03-01

172

350Kv X-Ray Set for the Calibration of Radiological Protection Instruments.  

National Technical Information Service (NTIS)

This report describes the commissioning of the 350 Kv Pantak HF 420 C X-ray set to be used for the calibration of radiological protection instruments and to determine their response as a function of energy. The work presented in this report was carried ou...

S. S. Ahmad

1984-01-01

173

A robot-based detector manipulator system for a hard x-ray nanoprobe instrument.  

SciTech Connect

This paper presents the design of a robot-based detector manipulator for microdiffraction applications with a hard X-ray nanoprobe instrument system being constructed at the Advanced Photon Source (APS) for the Center for Nanoscale Materials (CNM) being constructed at Argonne National Laboratory (ANL). Applications for detectors weighing from 1.5 to 100 kg were discussed in three configurations.

Shu, D., Maser, J., Holt, M. , Winarski, R., Preissner, C.,Lai, B., Vogt, S., Stephenson, G.B.

2007-11-11

174

X ray absorption spectroscopy of dense, shock compressed, laser plasma  

NASA Astrophysics Data System (ADS)

The central theme of this work involves the diagnosis of shock compressed highly correlated laser plasmas, by observation of the Extended X-ray Absorption Fine Structure (EXAFS) in the absorption spectrum. Measurements have been made using a plane crystal mini-spectrometer and a spectrometer purpose built for EXAFS measurement which employed an elliptically curved x-ray dispersing crystal. Chapter 1 serves as a very brief introduction to the plasma state, and describes how the strongly coupled plasmas which are of interest to this work are created, through laser interaction, and theoretically modelled. Chapters 2, 3 and 4 concern the development and the testing of the elliptical spectrometer. Chapter 2 introduces the theoretical models and concepts which have been developed to predict the behavior of the spectrometer, and demonstrate how these predictions have influenced the spectrometer design. Chapter 3 charts the development of the EXAFS spectrometer from the early plane crystal geometry to the successful elliptical crystal arrangement. Also described is the process by which the x-ray dispersing crystals are bent to the correct elliptical contour. Chapter 4 describes the testing of the elliptical spectrometer prior to EXAFS measurement, in order to assess the viability of the spectrometer alignment procedure and the general viability of the spectrometer as a diagnostic device. Chapter 5 is concerned with the experimental details of the plasma EXAFS studies. The use of both planar and elliptical crystal spectrometers, in the VULCAN glass laser environment is described. Chapter 6 is concerned with the analysis of the experimental results. The models by which the density, temperature and ion correlation are calculated are introduced, and applied to EXAFS measurements from both spectrometers. The results are presented in tabular and graphical form and discussed at length. Chapter 7 assesses the feasibility of replacing x-ray film with a commercially available solid state detector in order to measure the x-ray emission from laser produced plasma. The two types of detector and their relative merits are described, and the results of an experiment designed to compare and contrast their performance is presented. Chapter 8 is a summary of the work presented in this thesis, and suggests some possible avenues for future research.

Goodman, D. A.

175

High Resolution X-Ray Spectroscopy with a Microcalorimeter  

SciTech Connect

Energy-dispersive spectrometry (EDS) is often the preferred choice for X-ray microanalysis, but there are still many disadvantages associated with EDS, the most significant of which is the relatively poor energy resolution, which limits detection sensitivity and the ability to distinguish among closely spaced spectral features, limiting even qualitative analysis. A new type of EDS detector that operates on the principle of microcalorimetry has the potential to eliminate this shortcoming, reaching resolutions an order of magnitude better. The detector consists of an absorber in thermal contact with a transition edge sensor (TES). An X-ray from the specimen hits the absorber and manifests itself as a change in temperature. Because the system is kept at 80 mK, the heat capacity is low and the temperature spike is observable. The TES responds to the increase in temperature by transitioning from its superconducting to its normal conducting state, thus sharply raising the overall resistance of the circuit. The circuit is kept at a constant voltage, so the increase in resistance is manifested as a decrease in current flow. This decrease in current is measured by a superconducting quantum interference device (SQUID), and by integrating the current over time, the energy of the incident X-ray is determined. The prototype microcalorimeter was developed by NIST, and this technology is now available commercially through a partnership between Vericold Technologies and EDAX International. ORNL has received the first of these commercial microcalorimeters in the United States. The absorber in this detector is gold, and the TES consists of a gold-iridium bilayer. It is designed to offer spectral resolution of 10-15 eV at a count rate of ~150 s-1. The goal of this project was to analyze and document the performance of the detector, with particular attention given to the effects of an X-ray optic used to improve collection efficiency, the multiple window system and any other sources of spectral artifacts. It was found that the detector is capable of distinguishing many L? and L? spectral lines, with a resolution between 13 and 17 eV. It was also observed that the background has an unusual shape, and this is largely being attributed to the variable transmission coefficient of the X-ray optic. These preliminary results suggest that the microcalorimeter has a high potential for use in microanalysis, but more work to quantify its capabilities must still be done.

Norrell, J.; Anderson, I.

2005-01-01

176

X-Ray Diffractometry and X-Ray Photoelectron Spectroscopy Investigations of Nanocrytalline Hydroxyapatite Synthesized by a Hydroxide Gel Technique  

NASA Astrophysics Data System (ADS)

Nanocrystalline hydroxyapatite (HA), Ca10(PO4)6(OH)2, has been synthesized by a precipitate-conversion technique using hydroxide gel. Hydroxyapatite crystallizes in a hexagonal structure (space group; P63/m) having lattice parameters; a=9.407 Å and c=6.883 Å, and around 37 nm in size for the 800°C-annealed sample. Substantial crystalline characteristics are observed for the material heat-treated at 80°C. With the increase of air-annealing temperature, from 80°C to 800°C, lattice expansion along all crystallographic axes occurs indicating a structural change in the HA lattice. These results have been attributed to (1) the formation of a relative Ca2+ deficiency in HA that incorporates various chemical species in the anionic sites compared to their lower temperature air-annealed counterparts, and (2) the precipitation of CaO with increasing air-annealing temperature. The X-ray photoelectron spectroscopy studies indicate a distorted anionic structure and two electronic states for the O1 s, corroborating the observed X-ray diffraction results.

Panda, Rabi Narayan; Hsieh, Ming-Fa; Chung, Ren-Jei; Chin, Tsung-Shune

2001-08-01

177

A novel von Hamos spectrometer for efficient X-ray emission spectroscopy in the laboratory.  

PubMed

We present a novel, highly efficient von Hamos spectrometer for X-ray emission spectroscopy (XES) in the laboratory using highly annealed pyrolitic graphite crystals as the dispersive element. The spectrometer covers an energy range from 2.5 keV to 15 keV giving access to chemical speciation and information about the electronic configuration of 3d transition metals by means of the K? multiplet. XES spectra of Ti compounds are presented to demonstrate the speciation capabilities of the instrument. A spectral resolving power of E/?E = 2000 at 8 keV was achieved. Typical acquisition times range from 10?min for bulk material to hours for thin samples below 1??m. PMID:24880356

Anklamm, Lars; Schlesiger, Christopher; Malzer, Wolfgang; Grötzsch, Daniel; Neitzel, Michael; Kanngießer, Birgit

2014-05-01

178

Atomic physics studies of highly charged ions on tokamaks using x-ray spectroscopy  

SciTech Connect

An overview is given of atomic physics issues which have been studied on tokamaks with the help resolution x-ray spectroscopy. The issues include the testing of model calculations predicting the excitation of line radiation, the determination of rate coefficients, and accurate atomic structure measurements. Recent research has focussed primarily on highly charged heliumlike (22 less than or equal to Z less than or equal to 28) and neonlike (34 less than or equal to Z less than or equal to 63) ions, and results are presented from measurements on the PLT and TFTR tokamaks. Many of the measurements have been aided by improved instrumental design and new measuring techniques. Remarkable agreement has been found between measurements and theory in most cases. However, in this review those areas are stressed where agreement is worst and where further investigations are needed. 19 refs., 13 figs., 2 tabs.

Beiersdorfer, P.; von Goeler, S.; Bitter, M.; Hill, K.W.

1989-07-01

179

Constellation-X Spectroscopy X-ray Telescope Assembly and Alignment  

NASA Astrophysics Data System (ADS)

The Constellation-X mission is a follow-on to the current Chandra and XMM missions. It will place in orbit an array of four identical X-ray telescopes that will work in unison, having a substantial increase in effective area, energy resolution, and energy bandpass over current missions. To accomplish these ambitious increases new optics technologies must be exploited. The primary instrument for the mission is the Spectroscopy X-Ray Telescope (SXT), which covers the 0.2 to 10 keV band with a combination of two x-ray detectors: a reflection grating spectrometer (RGS) with CCD readout, and a micro-calorimeter. Mission requirements are an effective area of 15,000 cm2 near 1.25 keV, 6,000 cm2 near 6 keV, and a 15 arcsec (HPD) resolution requirement with a goal of 5 arcsec. The Constellation-X SXT uses a segmented design with lightweight replicated optics. A technology development program is being pursued with the intent of demonstrating technical readiness prior to the program new start. Key elements of the program include the replication of the optical elements, assembly and alignment of the optics into a complete mirror assembly and demonstration of production techniques needed for fabrication of multiple units. In this paper we present the development of SXT assembly and alignment techniques and describe recent work and current status on the first of these assemblies, the Optical Assembly Pathfinder, in which precision mechanical techniques and optical metrology are used to assemble and align the flexible optical elements.

Podgorski, William A.; Content, David A.; Glenn, Paul E.; Hair, Jason H.; Petre, Robert; Saha, Timo T.; Schattenburg, Mark L.; Stewart, Jeff; Zhang, William W.

2003-03-01

180

Fast Detection Allows Analysis of the Electronic Structure of Metalloprotein by X-ray Emission Spectroscopy at Room Temperature  

PubMed Central

The paradigm of “detection-before-destruction” was tested for a metalloprotein complex exposed at room temperature to the high x-ray flux typical of third generation synchrotron sources. Following the progression of the x-ray induced damage by Mn K? x-ray emission spectroscopy, we demonstrated the feasibility of collecting room temperature data on the electronic structure of native Photosystem II, a trans-membrane metalloprotein complex containing a Mn4Ca cluster. The determined non-damaging observation timeframe (about 100 milliseconds using continuous monochromatic beam, deposited dose 1*107 photons/µm2 or 1.3*104 Gy, and 66 microseconds in pulsed mode using pink beam, deposited dose 4*107 photons/µm2 or 4.2*104 Gy) is sufficient for the analysis of this protein’s electron dynamics and catalytic mechanism at room temperature. Reported time frames are expected to be representative for other metalloproteins. The described instrumentation, based on the short working distance dispersive spectrometer, and experimental methodology is broadly applicable to time-resolved x-ray emission analysis at synchrotron and x-ray free-electron laser light sources.

Davis, Katherine M.; Mattern, Brian A.; Pacold, Joseph I.; Zakharova, Taisiya; Brewe, Dale; Kosheleva, Irina; Henning, Robert W.; Graber, Timothy J.; Heald, Steve M.; Seidler, Gerald T.; Pushkar, Yulia

2012-01-01

181

A microprocessor controlled instrument for measurement and display of X-ray waveforms  

NASA Astrophysics Data System (ADS)

The National Center for Devices and Radiological Health has developed a radiation measurement instrument for use by Food and Drug Administration personnel in determining compliance of X-ray machines with applicable performance standards. The instrument measures radiation exposures from 1 mR to 590 R and exposure times from 1 msec to 5.76 seconds. It is compact, lightweight and battery powered, and suitable for field use.

Lee, T. R.

1983-04-01

182

Prototyping a Global Soft X-ray Imaging Instrument for Heliophysics, Planetary Science, and Astrophysics Science  

NASA Technical Reports Server (NTRS)

We describe current progress in the development of a prototype wide field-of-view soft X-ray imager that employs Lobster-eye optics and targets heliophysics, planetary, and astrophysics science. The prototype will provide proof-of-concept for a future flight instrument capable of imaging the entire dayside magnetosheath from outside the magnetosphere. Such an instrument was proposed for the FSA AXIOM mission

Collier, Michael R.; Porter, F. Scott; Sibeck, David G.; Carter, Jenny A.; Chiao, Meng P.; Chornay, Dennis J.; Cravens, Thomas; Galeazzi, Massimiliano; Keller, John W.; Koutroumpa, Dimitra; Kuntz, Kip; Read, Any M.; Robertson, Ina P.; Sembay, Steve; Snowden, Steven; Thomas, Nick

2012-01-01

183

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

NASA Astrophysics Data System (ADS)

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.

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.

2007-09-01

184

In situ high-resolution X-ray photoelectron spectroscopy - Fundamental insights in surface reactions  

NASA Astrophysics Data System (ADS)

Since the advent of third generation synchrotron light sources optimized for providing soft X-rays up to 2 keV, X-ray photoelectron spectroscopy (XPS) has been developed to be an outstanding tool to study surface properties and surface reactions at an unprecedented level. The high resolution allows identifying various surface species, and for small molecules even the vibrational fine structure can be resolved in the XP spectra. The high photon flux reduces the required measuring time per spectrum to the domain of a few seconds or even less, which enables to follow surface processes in situ. Moreover, it also provides access to very small coverages down to below 0.1% of a monolayer, enabling the investigation of minority species or processes at defect sites. The photon energy can be adjusted according to the requirement of a particular experiment, i.e., to maximize or minimize the surface sensitivity or the photoionization cross-section of the substrate or the adsorbate. For a few instruments worldwide, a next step forward was taken by combining in situ high-resolution spectrometers with supersonic molecular beams. These beams allow to control and vary the kinetic and internal energies of the incident molecules and provide a local pressure of up to ~10-5 mbar, which can be switched on and off in a controllable way, thus offering a well-defined time structure to study adsorption or reaction processes.

Papp, Christian; Steinrück, Hans-Peter

2013-11-01

185

Timing and Spectroscopy of Accreting X-ray Pulsars: the State of Cyclotron Line Studies  

NASA Astrophysics Data System (ADS)

A great deal of emphasis on timing in the RXTE era has been on pushing toward higher and higher frequency phenomena, particularly kHz QPOs. However, the large areas of the RXTE pointed instruments provide another capability which is key for the understanding of accreting X-ray pulsars - the ability to accumulate high quality spectra in a limited observing time. For the accreting X-ray pulsars, with their relatively modest spin frequencies, this translates into an ability to study broad band spectra as a function of pulse phase. This is a critical tool, as pulsar spectra are strong functions of the geometry of the ``accretion mound'' and the observers' viewing angle to the ~1012 G magnetic field. In particular, the appearance of ``cyclotron lines'' is sensitively dependent on the viewing geometry, which must change with the rotation of the star. These spectral features, seen in only a handful of objects, are quite important, as they give us our only direct measure of neutron star magnetic fields. Furthermore, they carry a great deal of information as to the geometry and physical conditions in the accretion mound. In this paper, we review the status of cyclotron line studies with the RXTE. We present an overview of phase-averaged results and give examples of observations which illustrate the power of phase-resolved spectroscopy.

Heindl, W. A.; Rothschild, R. E.; Coburn, W.; Staubert, R.; Wilms, J.; Kreykenbohm, I.; Kretschmar, P.

2004-07-01

186

X-ray imaging crystal spectroscopy for use in plasma transport research.  

PubMed

This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used to accurately constrain particle, momentum, and heat transport studies in a tokamak for the first time. Doppler tomography techniques have been extended to include propagation of statistical uncertainty due to photon noise, the effect of non-uniform instrumental broadening as well as flux surface variations in impurity density. These methods have been deployed as a suite of modeling and analysis tools, written in interactive data language (IDL) and designed for general use on tokamaks. Its application to the Alcator C-Mod XICS is discussed, along with novel spectral and spatial calibration techniques. Example ion temperature and radial electric field profiles from recent I-mode plasmas are shown, and the impact of poloidally asymmetric impurity density and natural line broadening is discussed in the context of the planned ITER x-ray crystal spectrometer. PMID:23206059

Reinke, M L; Podpaly, Y A; Bitter, M; Hutchinson, I H; Rice, J E; Delgado-Aparicio, L; Gao, C; Greenwald, M; Hill, K; Howard, N T; Hubbard, A; Hughes, J W; Pablant, N; White, A E; Wolfe, S M

2012-11-01

187

X-ray imaging crystal spectroscopy for use in plasma transport research  

SciTech Connect

This research describes advancements in the spectral analysis and error propagation techniques associated with x-ray imaging crystal spectroscopy (XICS) that have enabled this diagnostic to be used to accurately constrain particle, momentum, and heat transport studies in a tokamak for the first time. Doppler tomography techniques have been extended to include propagation of statistical uncertainty due to photon noise, the effect of non-uniform instrumental broadening as well as flux surface variations in impurity density. These methods have been deployed as a suite of modeling and analysis tools, written in interactive data language (IDL) and designed for general use on tokamaks. Its application to the Alcator C-Mod XICS is discussed, along with novel spectral and spatial calibration techniques. Example ion temperature and radial electric field profiles from recent I-mode plasmas are shown, and the impact of poloidally asymmetric impurity density and natural line broadening is discussed in the context of the planned ITER x-ray crystal spectrometer.

Reinke, M. L.; Podpaly, Y. A.; Hutchinson, I. H.; Rice, J. E.; Gao, C.; Greenwald, M.; Howard, N. T.; Hubbard, A.; Hughes, J. W.; White, A. E.; Wolfe, S. M. [MIT-Plasma Science and Fusion Center, Cambridge, Massachusetts 02139 (United States); Bitter, M.; Delgado-Aparicio, L.; Hill, K.; Pablant, N. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2012-11-15

188

Fundamental studies of X-ray and secondary electron spectroscopy  

NASA Astrophysics Data System (ADS)

Microanalysis of submicron particles in the Scanning Electron Microscope (SEM) is only possible by using low incident electron beam energies due to smaller interaction volume and suppressed beam induced charging. Such low beam energies must use L- and M-lines rather than the familiar K-lines. The information about the fundamental parameters of X-ray emission and transport at low energies is limited, so the use of L- and M-lines is problematic. The rate of generation of X-rays from an element irradiated at some energy E depends on the product of the ionization cross-section sigma(E) and the fluorescent yield o. Unfortunately neither of these quantities is well established independently, especially outside of the K-series of lines. Therefore the absolute X-ray generation efficiencies (photons/electron) were directly measured and parameterized for a wide range of K, L , and M lines from different elements. It is anticipated that a complete set of such data would be of great value in applications such as spectrum simulation and standardless analysis. Secondary electron spectra have been collected from both pure elements and from compounds examined under conditions approximating those found in a scanning electron microscope. Despite the presence of substantial surface contamination these spectra are found to be reproducible and characteristic of the underlying material. Typically the peak in such spectra is found to be at an energy of about 5 eV, and 50% of the total secondary electron emission falls within the range 0--12 eV. These data may be of value for the design of detectors for scanning microscopy and might have applications for microanalysis.

Mulapudi, Satya Prasad

189

Two-color phase-sensitive x-ray pump-probe spectroscopy  

SciTech Connect

X-ray pump-probe spectroscopy is studied theoretically. It is shown that two-color--optical+x-ray--excitation with constant phase of the pump radiation exhibits strong interference between the one- and two-photon excitation channels. This effect is found to be large for both long and short pump pulses, while the interference vanishes for x-ray pulses longer than one cycle of the pump field. It is predicted that the spectral shape of x-ray absorption is strongly influenced by the absolute phase of the pump light. A strong sensitivity of the x-ray absorption and/or photoionization profile to the phase and detuning of the pump field is predicted, as well as to the duration of the x-ray pulse. Our simulations display oscillations of x-ray absorption as a function of the delay time. This effect allows the synchronization of the x-ray pulse relative to the ''comb'' of the pump radiation. The interference pattern copies the temporal and space distribution of the pump field. We pay special attention to the role of molecular orientation for the interference effect.

Guimaraes, F.F. [Theoretical Chemistry, Roslagstullsbacken 15, Royal Institute of Technology, S-106 91 Stockholm (Sweden); Departamento de Quimica, Universidade Federal de Minas Gerais, Avenida Antonio Carlos, 6627, CEP-31270-901, Belo Horizonte, Minais Gerais (Brazil); Kimberg, V.; Gel'mukhanov, F.; Aagren, H. [Theoretical Chemistry, Roslagstullsbacken 15, Royal Institute of Technology, S-106 91 Stockholm (Sweden)

2004-12-01

190

Observing photochemical transients by ultrafast x-ray absorption spectroscopy.  

PubMed

Accurate determination of the transient electronic structures, which drive photochemical reactions, is crucial in chemistry and biology. We report the detection of transient chemical changes on the picosecond time scale by x-ray-absorption near-edge structure of photoexcited aqueous [Ru(bpy)(3)](2+). Upon ultrashort laser pulse excitation a charge transfer excited state having a 300 ns lifetime is formed. We detect the change of oxidation state of the central Ru atom at its L3 and L2 edges, at a temporal resolution of 100 ps with the zero of time unambiguously determined. PMID:12570459

Saes, Melanie; Bressler, Christian; Abela, Rafael; Grolimund, Daniel; Johnson, Steven L; Heimann, Philip A; Chergui, Majed

2003-01-31

191

X-ray Spectroscopy of Directly Driven Cylindrical Implosions  

Microsoft Academic Search

X-ray spectra from a chlorinated polystyrene marker layer in a series of directly driven cylindrical implosions are presented and analyzed. The 4mum thick, 500mum long C_8H_6Cl2 (1.42g\\/cc) annular spectroscopic tracer layer is centrally located on the interior surface of the 20mum thick, 2250mum long polystyrene (1.044g\\/cc) 860mu m inner diameter cylindrical shell. The shell is filled with polystyrene foam (60mg\\/cc).(Barnes,

D. Haynes; C. Hooper; N. Delamater; C. Barnes; J. Oertel; G. Pollak; D. Tubbs; R. Watt; T. Boehly; D. Bradley; P. Jaanimagi; J. Knauer

1998-01-01

192

Radiation study of swept-charge devices for the Chandrayaan-1 X-ray Spectrometer (C1XS) instrument  

NASA Astrophysics Data System (ADS)

The Chandrayaan-1 X-ray Spectrometer (C1XS) will be launched as part of the Indian Space Research Organisation (ISRO) Chandrayaan-1 payload in September 2008, arriving at the Moon within 7 days to begin a two year mission in lunar orbit conducting mineralogical surface mapping over the range of 1 - 10 keV. The detector plane of the instrument consists of twenty four e2v technologies CCD54 swept-charge devices (SCDs). Such devices were first flown in the Demonstration of a Compact Imaging X-ray Spectrometer (D-CIXS) instrument onboard SMART-1 [4, 5]. The detector plane in each case provides a total X-ray collection area of 26.4 cm2. The SCD is capable of providing near Fano-limited spectroscopy at -10°C, and at -20°C, near the Chandrayaan-1 mission average temperature, it achieves a total system noise of 6.2 electrons r.m.s. and a FWHM of 134 eV at Mn-K?. This paper presents a brief overview of the C1XS mission and a detailed study of the effects of proton irradiation on SCD operational performance.

Gow, J.; Smith, D. R.; Holland, A. D.; Maddison, B.; Howe, C.; Grande, M.; Sreekumar, P.; Huovelin, J.

2008-08-01

193

X-ray spectroscopy of GRO J1655-40  

NASA Astrophysics Data System (ADS)

After seven years in quiescence, GRO J1655-40 started a new outburst in February 2005, rising to a high/soft state in March 2005. We report here the results of four XMM-Newton observations performed on 27 February 2005 in the low/hard state, and on three consecutive days in March 2005 during the rise of the source to its high/soft state. The X-ray spectrum of GRO J1655-40 was dominated in the high/soft state by the thermal emission from the accretion disk, with a maximum temperature of 1.3 keV. We detected two absorption lines in the EPIC-pn spectra at 6.7-6.8 and 7.8-8.0 keV, which could be identified as the K? and K? lines of either blended Fe XXV and Fe XXVI or blueshifted Fe XXV. We found no orbital dependence on the X-ray properties, which provides an upper limit for the inclination of the system of 73 ° .

Sala, Gloria; Greiner, J.; Vink, J.; Haberl, F.

194

Very high resolution UV and X-ray spectroscopy and imagery of solar active regions  

NASA Technical Reports Server (NTRS)

A scientific investigation of the physics of the solar atmosphere, which uses the techniques of high resolution soft X-ray spectroscopy and high resolution UV imagery, is described. The experiments were conducted during a series of three sounding rocket flights. All three flights yielded excellent images in the UV range, showing unprecedented spatial resolution. The second flight recorded the X-ray spectrum of a solar flare, and the third that of an active region. A normal incidence multi-layer mirror was used during the third flight to make the first astronomical X-ray observations using this new technique.

Bruner, M.; Brown, W. A.; Haisch, B. M.

1987-01-01

195

Advanced experimental applications for x-ray transmission gratings spectroscopy using a novel grating fabrication method  

SciTech Connect

A novel fabrication method for soft x-ray transmission grating and other optical elements is presented. The method uses focused-ion-beam technology to fabricate high-quality free standing grating bars on transmission electron microscopy grids. High quality transmission gratings are obtained with superb accuracy and versatility. Using these gratings and back-illuminated CCD camera, absolutely calibrated x-ray spectra can be acquired for soft x-ray source diagnostics in the 100-3000 eV spectral range. Double grating combinations of identical or different parameters are easily fabricated, allowing advanced one-shot application of transmission grating spectroscopy. These applications include spectroscopy with different spectral resolutions, bandwidths, dynamic ranges, and may serve for identification of high-order contribution, and spectral calibrations of various x-ray optical elements.

Hurvitz, G.; Ehrlich, Y.; Shpilman, Z.; Levy, I.; Fraenkel, M. [Plasma Physics Department, Applied Physics Division, Soreq NRC, Yavne (Israel); Strum, G. [Solid State Department, Applied Physics Division, Soreq NRC, Yavne (Israel)

2012-08-15

196

The NOAA Goes-12 Solar X-Ray Imager (SXI) 1. Instrument, Operations, and Data  

NASA Astrophysics Data System (ADS)

The Solar X-ray Imager (SXI) was launched 23 July 2001 on NOAA’s GOES-12 satellite and completed post-launch testing 20 December 2001. Beginning 22 January 2003 it has provided nearly uninterrupted, full-disk, soft X-ray solar images, with a continuous frame rate significantly exceeding that for previous similar instruments. The SXI provides images with a 1 min cadence and a single-image (adjustable) dynamic range near 100. A set of metallic thin-film filters provides temperature discrimination in the 0.6 6.0 nm bandpass. The spatial resolution of approximately 10 arcsec FWHM is sampled with 5 arcsec pixels. Three instrument degradations have occurred since launch, two affecting entrance filters and one affecting the detector high-voltage system. This work presents the SXI instrument, its operations, and its data processing, including the impacts of the instrument degradations. A companion paper (Pizzo et al., this issue) presents SXI performance prior to an instrument degradation that occurred on 5 November 2003 and thus applies to more than 420000 soft X-ray images of the Sun.

Hill, S. M.; Pizzo, V. J.; Balch, C. C.; Biesecker, D. A.; Bornmann, P.; Hildner, E.; Lewis, L. D.; Grubb, R. N.; Husler, M. P.; Prendergast, K.; Vickroy, J.; Greer, S.; Defoor, T.; Wilkinson, D. C.; Hooker, R.; Mulligan, P.; Chipman, E.; Bysal, H.; Douglas, J. P.; Reynolds, R.; Davis, J. M.; Wallace, K. S.; Russell, K.; Freestone, K.; Bagdigian, D.; Page, T.; Kerns, S.; Hoffman, R.; Cauffman, S. A.; Davis, M. A.; Studer, R.; Berthiaume, F. E.; Saha, T. T.; Berthiume, G. D.; Farthing, H.; Zimmermann, F.

2005-02-01

197

High resolution X- and gamma-ray spectroscopy of cosmic X-ray sources  

NASA Technical Reports Server (NTRS)

A high resolution X-ray spectrometer and large area phoswich detector were designed and co-aligned in a common elevation mounting in order to measure solar and cosmic X-ray and gamma ray emission in the 13 to 600 KeV energy range from a balloon. The instrument is described and results obtained for the Crab Nebula, the supernova remnant Cas A, and the Sun are discussed and analyzed.

Lin, R. P.

1983-01-01

198

Thiol-capped ferromagnetic Au nanoparticles investigated by Au L3 x-ray absorption spectroscopy  

Microsoft Academic Search

Different dodecanethiol capped Au nanoparticles (NP) with similar sizes (~2 nm) but different ferromagnetic signals at room temperature have been investigated by means of x-ray absorption spectroscopy at the Au L3-edge. The reversion of the x-ray magnetic circular dichroism signal with the change of sign of the external applied magnetic field confirms the location of the magnetism at the Au

J. S. Garitaonandia; E. Goikolea; M. Insausti; M. Suzuki; N. Kawamura; H. Osawa; I. Gil Del Muro; K. Suzuki; J. D. Cashion; C. Gorria; F. Plazaola; T. Rojo

2009-01-01

199

X-ray absorption spectroscopy: A fluorescence detection system based on a plastic scintillator  

Microsoft Academic Search

A fluorescence detection system based on a plastic scintillator is presented that can be used for both X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine-structure (EXAFS) spectroscopy. Its counting rate is limited by the pulsation frequency of the synchrotron radiation (3.16×106 counts s-1), and can be theoretically extended to roughly 5×107 counts s-1 if used on a multibunch

G. Tourillon; D. Guay; M. Lemonnier; F. Bartol; M. Badeyan

1990-01-01

200

Properties of Liquid Silicon Observed by Time-Resolved X-Ray Absorption Spectroscopy  

NASA Astrophysics Data System (ADS)

Time-resolved x-ray spectroscopy at the Si L edges is used to probe the electronic structure of an amorphous Si foil as it melts following absorption of an ultrafast laser pulse. Picosecond temporal resolution allows observation of the transient liquid phase before vaporization and before the liquid breaks up into droplets. The melting causes changes in the spectrum that match predictions of molecular dynamics and ab initio x-ray absorption codes.

Johnson, S. L.; Heimann, P. A.; Lindenberg, A. M.; Jeschke, H. O.; Garcia, M. E.; Chang, Z.; Lee, R. W.; Rehr, J. J.; Falcone, R. W.

2003-10-01

201

Crystal optics for hard-X-ray spectroscopy of highly charged ions  

Microsoft Academic Search

A twin crystal-spectrometer assembly, operated in the focusing compensated asymmetric Laue geometry has been developed for accurate spectroscopy of fast highly charged heavy ions in the hard-X-ray region. Coupled to the focusing crystal optics is a specially developed two-dimensional position-sensitive X-ray detector which is necessary for retaining spectral resolution also for fast moving sources. We summarize the crystal optics and

H. F. Beyer; D. Attia; D. Banas; E.-O. Le Bigot; F. Bosch; J.-Cl. Dousse; E. Förster; A. Gumberidze; S. Hagmann; S. Heß; J. Hoszowska; P. Indelicato; P. Jagodzinski; Chr. Kozhuharov; Th. Krings; D. Liesen; X. Ma; B. Manil; I. Mohos; M. Pajek; D. Proti?; R. Reuschl; J. Rzadkiewicz; A. Simionovici; U. Spillmann; Z. Stachura; Th. Stöhlker; M. Trassinelli; S. Trotsenko; A. Warczak; O. Wehrhan; E. Ziegler

2009-01-01

202

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

Microsoft Academic Search

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 L3-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

Michel L. Schlegel; Pascal Reiller; Florence Mercier-Bion; Nicole Barré; Valérie Moulin

2006-01-01

203

Nuclear resonant x-ray spectroscopy of (Mg,Fe)SiO orthoenstatites  

Microsoft Academic Search

We present nuclear resonant inelastic X-ray scattering (NRIXS) and synchrotron Moessbauer spectroscopy (SMS) measurements, both nuclear resonant X-ray spectroscopic methods, on synthetic samples of orthoenstatite-structured (Mg,Fe)SiO, a representative component in Earth's upper mantle. All measurements were performed at ambient conditions. NRIXS spectra were measured for three samples of orthoenstatite containing 20, 13, and 7 mol% FeSiO. The Debye sound velocities

Jennifer M. Jackson; Emily A. Hamecher; Wolfgang Sturhahn

2009-01-01

204

X-ray spectroscopy of z-pinches in implosions of wire arrays with combined materials  

Microsoft Academic Search

Summary form only given. Time-resolved laser-probe diagnostics and gated X-ray imaging of star-like wire array Z-pinch implosions have shown implosion characteristics that are more stable than those of other types of wire arrays on the Zebra generator. Here, we study the plasma conditions achieved in star-like wire arrays implosions using time-integrated and spatially-resolved X-ray spectroscopy. To this end, spectroscopic data

P. Hakel; R. C. Mancini; V. V. Ivanov; A. Haboub; J. M. Kindel

2009-01-01

205

Watching energy transfer in metalloporphyrin heterodimers using stimulated X-ray Raman spectroscopy  

PubMed Central

Understanding the excitation energy transfer mechanism in multiporphyrin arrays is key for designing artificial light-harvesting devices and other molecular electronics applications. Simulations of the stimulated X-ray Raman spectroscopy signals of a Zn/Ni porphyrin heterodimer induced by attosecond X-ray pulses show that these signals can directly reveal electron–hole pair motions. These dynamics are visualized by a natural orbital decomposition of the valence electron wavepackets.

Zhang, Yu; Healion, Daniel; Mukamel, Shaul

2013-01-01

206

Characterization of CdTe Detectors for Quantitative X-ray Spectroscopy  

Microsoft Academic Search

Silicon diodes have traditionally been the detectors of choice for quantitative X-ray spectroscopy. Their response has been very well characterized and existing software algorithms process the spectra for accurate, quantitative analysis. But Si diodes have limited sensitivity at energies above 30 keV, while recent regulations require measurement of heavy metals such as lead and mercury, with K X-ray emissions well

Robert H. Redus; John A. Pantazis; Thanos J. Pantazis; Alan C. Huber; Brian J. Cross

2009-01-01

207

Combined in situ X-ray absorption and diffuse reflectance infrared spectroscopy: An attractive tool for catalytic investigations  

NASA Astrophysics Data System (ADS)

Catalysis investigations are often followed in a range of spectroscopic techniques. While diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS) can be done on a bench-top instrument, X-ray absorption spectroscopy (XAS) techniques, such as extended X-ray absorption fine structure (EXAFS) and X-ray absorption near-edge structure (XANES) require synchrotron light. In order to ensure the same conditions during in situ catalysis for each method, a combined XAS/DRIFTS has been developed at beamline X18A at the National Synchrotron Light Source, Brookhaven National Laboratory. A rapid-scan FTIR spectrometer capable of both mid- and far-infrared measurements is equipped with an arm to redirect the IR beam outside the spectrometer. An in situ reaction chamber, equipped with glassy carbon windows for X-ray light and a KBr window for IR light passage is installed firmly on the arm. The reaction cell can be heated to 600 °C and allows passage of gases through the catalyst so that both XAS and DRIFTS techniques can be done simultaneously in controlled environment conditions. Together with a fast-moving monochromator for quick-EXAFS and mass-spectrometric residual gas analysis, this new tool is a powerful method for testing catalytic reactions in real time.

Marinkovic, N. S.; Wang, Q.; Barrio, L.; Ehrlich, S. N.; Khalid, S.; Cooper, C.; Frenkel, A. I.

2011-09-01

208

High resolution X-ray spectroscopy from the Einstein Observatory  

NASA Technical Reports Server (NTRS)

Results obtained from the Focal Plane Crystal Spectrometer (FPCS) are presented with particular reference to supernova remnants Puppis A and Cas A in the Galaxy, and N132D and N63A in the Large Magellanic Cloud. A schematic diagram of the FPCS is given, and spectrum reconstruction is outlined, noting that the final spectrum consists of a histogram of counting rate vs. energy corrected for the exposure time in each energy bin. Consideration is also given to the Virgo cluster and its two X-ray components: the hot exponent extending throughout much of the cluster and a cooler, 'halo', component centered on M87. FPCS observations of central M87 are presented, and it is postulated that the central portion of the M87 'halo' source contains material with a dominant temperature near 10 to the 7th K or below about 2 x 10 to the 6th K.

Winkler, P. F.; Canizares, C. R.; Clark, G. W.; Markert, T. H.; Berg, C.; Jernigan, J. G.; Schattenburg, M. L.

1980-01-01

209

X-Ray Spectroscopy of Shock-Ignition Implosions  

NASA Astrophysics Data System (ADS)

We discuss the observation and spectroscopic analysis of argon K-shell x-ray line spectra from argon-doped deuterium-filled OMEGA direct-drive shock-ignition implosions based on data recorded with streaked crystal spectrometers. The argon line spectrum is primarily emitted at the collapse of the implosion thus providing a spectroscopic signature of the state of the imploded core. The observed spectra includes parent and satellite line transitions in H-, He- and Li-like Ar ions thus covering a broad photon energy range from 3200 eV to 4200 eV with a spectral resolution power of approximately 500. Both optically thick and thin lines are simultaneously modeled, including line overlapping and Stark-broadening effects. The spectroscopic analysis results show core temperature and density time-histories associated with the collapse implosions. A comparison is also made with LILAC hydrodynamic simulations.

Mancini, R. C.; Florido, R.; Nagayama, T.; Tommasini, R.; Delettrez, J.; Regan, S. P.; Smalyuk, V.

2009-11-01

210

UPDATED ATOMIC DATA AND CALCULATIONS FOR X-RAY SPECTROSCOPY  

SciTech Connect

We describe the latest release of AtomDB, version 2.0.2, a database of atomic data and a plasma modeling code with a focus on X-ray astronomy. This release includes several major updates to the fundamental atomic structure and process data held within AtomDB, incorporating new ionization balance data, state-selective recombination data, and updated collisional excitation data for many ions, including the iron L-shell ions from Fe{sup +16} to Fe{sup +23} and all of the hydrogen- and helium-like sequences. We also describe some of the effects that these changes have on calculated emission and diagnostic line ratios, such as changes in the temperature implied by the He-like G-ratios of up to a factor of two.

Foster, A. R.; Smith, R. K.; Brickhouse, N. S. [Smithsonian Astrophysical Observatory, Cambridge, MA 02144 (United States); Ji, L. [Purple Mountain Observatory, CAS, 2 West Beijing Road, Nanjing, Jiangsu 210008, China. (China)

2012-09-10

211

Investigation of surface structure with X-ray absorption and electron emission spectroscopies  

NASA Astrophysics Data System (ADS)

The use of electron spectromicroscopy for the study of the chemical composition and electronic properties of surfaces, overlayers, and interfaces has become widely accepted. Improvements to the optics of instruments such as the X-ray photo electron emission microscope have pushed spectroscopic microscopies into the realm of very high spatial resolution, at and below 1 micrometer [1]. Coupled with the high spectral resolution available from third generation synchrotron sources, this spatial resolution allows the measurement of micro-X-ray absorption near-edge spectra in addition to the more typical electron emission spectra and diffraction patterns. Complementary to the experimental developments is the development of improved theoretical methods for computational modeling of X-ray absorption and emission spectroscopies. In the field of tribochemistry, zinc dialkyl dithiophosphate (ZDDP) has long been a topic of much study. ZDDP is widely used as an anti-wear additive in engine oils and there is interest in determining the decomposition products of ZDDP that provide this protection against friction. An analysis of X-ray absorption near-edge spectra of thermal films from ZDDP samples is presented, including a comparison of the Zinc L-edge spectra with model calculations [2]. It was found essential to carry out self-consistent calculations of the electronic structure for the modeling. For the techniques of electron diffraction, a new method for a full multiple-scattering calculation of diffraction patterns from crystals with two-dimensional periodicity parallel to the surface is presented [3]. The calculation makes use of Helmholtz's reciprocity principle to compute the path-reversed process of the back propagation of a photoelectron from the position of a distant detector to that of the emitting atom. Early application is demonstrated with simulations of 64 eV M2,3VV and 914 eV L 2,3VV Auger electron diffraction from a Cu(001) surface. The functionality of the path-reversed calculation is greatly increased by extension to photoelectron diffraction for crystal surfaces with many atoms per unit cell [4]. The results are essentially indistinguishable from those of a conventional forward-path calculation. Application to photoelectron diffraction for 955 eV O 1s emission from a MgO(001) surface shows good agreement with experiment.

Pauli, Mark Daniel

212

What Can Be Learned from X-Ray Spectroscopy Concerning Hot Gas in the Local Bubble and Charge Exchange Processes?  

NASA Technical Reports Server (NTRS)

Both solar wind charge exchange emission and diffuse thermal emission from the Local Bubble are strongly dominated in the soft X-ray band by lines from highly ionized elements. While both processes share many of the same lines, the spectra should differ significantly due to the different production mechanisms, abundances, and ionization states. Despite their distinct spectral signatures, current and past observatories have lacked the spectral resolution to adequately distinguish between the two sources. High-resolution X-ray spectroscopy instrumentation proposed for future missions has the potential to answer fundamental questions such as whether there is any hot plasma in the Local Hot Bubble, and if so, what are the abundances of the emitting plasma and whether the plasma is in equilibrium. Such instrumentation will provide dynamic information about the solar wind including data on ion species which are currently difficult to track. It will also make possible remote sensing of the solar wind.

Snowden, S. L.

2008-01-01

213

Applications of position sensitive germanium detectors for X-ray spectroscopy of highly charged heavy ions  

NASA Astrophysics Data System (ADS)

The spectroscopy of atomic transitions in the hard X-ray regime above 15 keV utilizing position-sensitive solid state detectors is discussed. Special emphasis is given to the current detector developments for X-ray spectroscopy of heavy ions at the ESR storage ring where applications for precision spectroscopy as well as for polarization studies are of particular interest. For both cases, the advantages and new possibilities which are opened up by position and energy resolving solid state detectors are illustrated by the presentation of first experiments.

Stöhlker, Th.; Banas, D.; Beyer, H. F.; Gumberidze, A.; Kozhuharov, C.; Kanter, E.; Krings, T.; Lewoczko, W.; Ma, X.; Protic, D.; Sierpowski, D.; Spillmann, U.; Tachenov, S.; Warczak, A.

2003-05-01

214

Neutron and synchrotorn x-ray small angle scattering instruments for applications in biology at the Brookhaven National Laboratory  

SciTech Connect

Facilities for small angle x-ray and neutron scattering are described, with emphasis on the characterization of the primary beam of the neutron instrument and the spectrometer control logic of the synchrotron instrument. (LEW)

Schoenborn, B.P.; Wise, D.S.; Schneider, D.K.

1983-01-01

215

A cosmic and solar X-ray and gamma-ray instrument for a scout launch  

NASA Technical Reports Server (NTRS)

An overview is presented for a set of simple and robust X-ray and gamma ray instruments which have both cosmic and solar objectives. The primary solar scientific objective is the study of the beaming of energetic electrons and ions in solar flares. The instrument will measure spectra and polarization of flare emissions up to 10 MeV. At X-ray energies both the directly emitted flux and the reflected albedo flux will be measured with a complement of six X-ray sensors. Each of these detectors will have a different high Z filter selected to optimize both the energy resolution and high rate capabilities in the energy band 10 to 300 keV. At energies greater than 100 keV seven 7.6 x 7.6 cm NaI and a set of 30 concentric plastic scattering detectors will record the spectra and polarization of electron bremsstrahlung and nuclear gamma rays. All of the components of the instrument are in existence and have passed flight tests for earlier space missions. The instrument will use a spinning solar oriented Scout spacecraft. The NaI detectors will act as a self-modulating gamma ray detector for cosmic sources in a broad angular band which lies at 90 degrees to the Sun-Earth vector and hence will scan the entire sky in 6 months.

Forrest, D. J.; Vestrand, W. T.; Chupp, E. L.

1988-01-01

216

Multivariate statistical analysis for x-ray photoelectron spectroscopy spectral imaging: Effect of image acquisition time  

Microsoft Academic Search

The acquisition of spectral images for x-ray photoelectron spectroscopy (XPS) is a relatively new approach, although it has been used with other analytical spectroscopy tools for some time. This technique provides full spectral information at every pixel of an image, in order to provide a complete chemical mapping of the imaged surface area. Multivariate statistical analysis techniques applied to the

D. E. Peebles; J. A. Ohlhausen; P. G. Kotula; S. Hutton; C. Blomfield

2004-01-01

217

Structural characterization of SrLaMnRuO 6 by synchrotron X-ray powder diffraction and X-ray absorption spectroscopy  

Microsoft Academic Search

Single-phase polycrystalline powder samples of SrLaMnRuO6 were prepared by solid-state synthesis method and its crystal structure was studied using synchrotron X-ray diffraction and X-ray absorption spectroscopies. The Rietveld analysis of the room temperature synchrotron X-ray diffraction data shows that it has a double perovskite structure with disordered arrangements of Sr\\/La and Mn\\/Ru and adopts orthorhombic space group Pbnm [a=5.5004(3)Å, b=5.5445(3)Å,

Javaid Bashir; Rubina Shaheen; Muhammad Nasir Khan

2008-01-01

218

X-ray spectroscopy with the Reflection Grating Spectrometer on-board of XMM.  

NASA Astrophysics Data System (ADS)

The X-ray Multi-Mirror (XMM) mission is the second of the four cornerstone projects of the ESA long-term programme for space science, Horizon 2000. The payload comprises three co-aligned high-throughput, imaging telescopes with a FOV of 30' and spatial resolution <20? Imaging CCD-detectors (EPIC) are placed in the focus of each telescope (with total effective area ?4000 cm2 at 1.5 keV). Behind two of the three telescopes, about half of the X-ray light is utilized by the Reflection Grating Spectrometer (RGS) (with maximum total effective area in first order of ?200 cm2 at 12 Å for both modules). The instruments are co-aligned and measure simultaneously with an optical monitor (1800-10000 Å, limiting magnitude 24m5, spatial resolution 1? FOV 8'). It is envisaged that the observatory is launched near the end of the 20th century in a deep eccentric orbit allowing for sensitive, long uninterrupted observations of a large variety of astrophysical sources. XMM offers the possibility to perform broadband (0.1-10 keV) imaging spectroscopy with a resolving power E/?E ? 5-60 with the EPIC, combined with high resolution (?? 0.04 Å, or E/? 150-800 in 1st order) spectroscopy between 5-35 Å with the RGS. Compared to the ASCA-SIS, the EPIC has the same spectral resolution, but more than 10 times larger effective area and spatial resolution, covering a wider energy range, while the RGS has comparable effective area, but at least 10 times more spectral resolution.

Brinkman, A. C.; Aarts, H. J. M.; den Boggende, A. J. F.; Dubbeldam, L.; den Herder, J. W.; Kaastra, J. S.; de Korte, P. A. J.; Mewe, R.; Hailey, C. J.; Kahn, S. M.; Paerels, F.; Branduardi-Raymont, G.; Bixler, J.; Thomsen, K.; Zehnder, A.

1996-02-01

219

Femtosecond Thomson scattering X-ray source based on laser wakefield accelerator for ultrafast X-ray absorption spectroscopy  

Microsoft Academic Search

A novel source of femtosecond keV X-ray pulses based on Thomson scattering from a terawatt laser wakefield accelerator is being developed for chemical studies. The characteristics of the source, based on recent calculations and experiments, are discussed. Due to its short pulse duration, high flux and collimation this X-ray source is very well suited for ultrafast time-resolved X-ray absorption experiments

D. A. Oulianov; R. A. Crowell; D. J. Gosztola; Y. Li

2005-01-01

220

A bent silicon crystal in the Laue geometry to resolve actinide x-ray fluorescence for x-ray absorption spectroscopy  

Microsoft Academic Search

A highly strained, curved silicon crystal in the Laue geometry has been used as a large area x-ray fluorescence analyzer for x-ray absorption spectroscopy. The analyzer is able to resolve the L? fluorescence lines for neighboring actinide elements. A large gain in the signal-to-background ratio has been achieved for low levels of Mo, Np, and Pu in a UO2 matrix.

A J Kropf; J A Fortner; R J Finch; J C Cunnane; C Karanfil

2005-01-01

221

Applications of Synchrotron-Based X-Ray Diffraction and X-Ray Absorption Spectroscopy to the Understanding of Poorly Crystalline and Metal-Substituted Iron Oxides  

Microsoft Academic Search

The octahedral site in iron oxides has been shown to undergo changes in its occupation when iron oxides form in the presence of single and multiple foreign metals in controlled laboratory settings as well as the natural environment. X-ray absorption spectroscopy coupled with the increased precision of synchrotron-based X-ray diffraction (SXRD) have shed new light on important basic mechanisms controlling

Balwant Singh; Markus Gräfe; Navdeep Kaur; Andrea Liese

2010-01-01

222

Characterization of Pumice-Supported Ag–Pd and Cu–Pd Bimetallic Catalysts by X-Ray Photoelectron Spectroscopy and X-Ray Diffraction  

Microsoft Academic Search

Bimetallic Ag–Pd and Cu–Pd catalysts supported on pumice have been prepared in order to be used in the selective hydrogenation of dienes. The catalysts were obtained by the classical impregnation method and in the case of the Cu–Pd system also by organometallic precursors. They were analysed by X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). XPS allowed us to determine

A. M. Venezia; L. F. Liotta; G. Deganello; Z. Schay; L. Guczi

1999-01-01

223

X-ray Diffraction and Absorption Spectroscopy in Pulsed High Magnetic Fields  

NASA Astrophysics Data System (ADS)

Recent results of high-magnetic-field X-ray diffraction and absorption spectroscopy experiments using pulsed magnets are reviewed. Pulsed magnetic fields of up to 30--40 T are utilized. Structural changes induced by magnetic fields in rare-earth intermetallic compounds, transition-metal oxides and low-dimensional quantum spin compounds are presented as results of X-ray diffraction experiments. The structural changes are interpreted by several mechanisms such as the interspin distance dependence of exchange interactions, the symmetry change owing to the geometrical frustration effect, and the Jahn--Teller effect. In addition to the Thomson scattering experiment, a magnetic X-ray scattering experiment on TbB4 has been conducted at 30 T. Regarding X-ray absorption spectroscopy, the valence state transition in magnetic fields is observed in Yb-, Ce-, and Eu-based intermetallic compounds. Magnetic-field-induced changes in the structural and electronic states in transition-metal and rare-earth compounds were investigated using X-ray absorption spectra. The microscopic magnetic properties were examined by X-ray magnetic circular dichroism.

Matsuda, Yasuhiro H.; Inami, Toshiya

2013-02-01

224

Embedded Design and Virtual Instrument Simplifies X-Ray Diffractometer Setup Automation  

Microsoft Academic Search

Embedded control programmable hardware and Windows-based Virtual Instruments (VI) simplify the design of automation in R&D laboratories. With minimal hardware and maximum support of software, the automation becomes more readily achievable (Jayapandian, J. Curr. Sci., 25 March 2006, 90(6) 765–70). A novel design is described for the control of a Siemens X-ray Diffractometer. The automation is achieved with custom-embedded hardware

J. Jayapandian; O. K. Sheela; A. Thiruarul; S. Kalavathi

2006-01-01

225

Imaging X-ray Thomson Scattering Concept for the Matter in Extreme Conditions Instrument at LCLS  

Microsoft Academic Search

The Linac Coherent Light Source at SLAC, an x-ray free electron laser tunable in the range 800 -- 8000 eV, with 2 x 10^12 photons in a 200 fsec pulse, is a revolutionary facility that will impact many fields of science, including high energy density (HED) laboratory plasmas. The Matter in Extreme Conditions (MEC) instrument at LCLS will use high-power

D. S. Montgomery; E. J. Gamboa

2010-01-01

226

Chandra high-resolution X-ray spectroscopy of Seyfert 1 galaxies  

NASA Astrophysics Data System (ADS)

We present the analysis of the X-ray spectra of the Seyfert 1 galaxies NGC 5548 and Mrk 279. The X-ray spectra were obtained with the LETGS and HETGS spectrometers of Chandra during two long campaigns involving HST-STIS for both sources as well as FUSE for Mrk 279. The combination of both the X-ray and UV spectroscopy allowed us to obtain unique spectral diagnostics of the AGN outflow. We found absorption lines spanning several orders of magnitude in ionization parameter. The derived column densities are in good agreement with models involving density-stratified streamer-like outflows. In addition to the narrow absorption lines, we found both narrow and broad X-ray emission lines, with physical parameters very similar to the optical/UV narrow and broad line regions. The Space Research Organization Netherlands is supported financially by NWO, the Netherlands Organization for Scientific Research.

Kaastra, J. S.

2004-05-01

227

Ultrafast conversions between hydrogen bonded structures in liquid water observed by femtosecond x-ray spectroscopy  

SciTech Connect

We present the first femtosecond soft x-ray spectroscopy in liquids, enabling the observation of changes in hydrogen bond structures in water via core-hole excitation. The oxygen K-edge of vibrationally excited water is probed with femtosecond soft x-ray pulses, exploiting the relation between different water structures and distinct x-ray spectral features. After excitation of the intramolecular OH stretching vibration, characteristic x-ray absorption changes monitor the conversion of strongly hydrogen-bonded water structures to more disordered structures with weaker hydrogen-bonding described by a single subpicosecond time constant. The latter describes the thermalization time of vibrational excitations and defines the characteristic maximum rate with which nonequilibrium populations of more strongly hydrogen-bonded water structures convert to less-bonded ones. On short time scales, the relaxation of vibrational excitations leads to a transient high-pressure state and a transient absorption spectrum different from that of statically heated water.

Wen, Haidan; Huse, Nils; Schoenlein, Robert W.; Lindenberg, Aaron M.

2010-05-01

228

Polarized X-ray absorption spectroscopy of cupric chloride dihydrate  

SciTech Connect

The authors report a detailed polarized single-crystal X-ray absorption spectroscopic study of CuCl{sub 2}{center_dot}2H{sub 2}O, with measurements at both the copper K-edge and the chlorine K-edge. The angular dependence of both dipole-allowed and quadrupole-allowed transitions is determined in detail for the copper K-edge. The formally dipole-forbidden, quadurople-allowed Cu K-edge 1s{r_arrow}3d transition behaves as a pure quadrupole transition, with no significant dipole contribution. The 1s{r_arrow}3d transition is found to have predominantly 3dx{sup 2}-y{sup 2} character, as expected, but evidence is also given for vacancies in a lower lying d orbital, possibly 3d{sub xz}, arising from the presence of d{pi}-d{pi} bonding with the chloride ligands. The chlorine K-edge data show a strongly polarized pre-edge resonance at {approximately}2821 eV, which can be interpreted in terms of a transition from the chlorine 1s orbital to an antibonding orbital with significant contributions from both chlorine 3p and the half-filled copper 3dx{sup 2}-y{sup 2} orbital.

Pickering, I.J.; George, G.N. [Stanford Univ., Stanford, CA (United States)

1995-06-07

229

Constellation-X spectroscopy X-ray telescope (SXT)  

NASA Astrophysics Data System (ADS)

We provide an overview of the Constellation-X SXT development program. We describe the performance requirements and goals, and the status of the technology development program. The SXT has a 1.6-meter diameter, a 10-meter focal length, and is to have an angular resolution exceeding 15 arc seconds. It has a modular design, incorporting lightweight, multiply nested, segmented Wolter Type I x-ray mirrors. All aspects of the design lend themselves to mass-production. The reflecting surfaces are produced by epoxy replication off precision mandrels onto glass substrates that have been accurately formed by thermal slumping. Coalignment of groups of relfectors to the required sub-micron accuracy is assisted by precison silicon micorstructures. Optical alignment is performed using the Centroid Detector Assembly originally developed for aligning the Chandra mirror. Recent efforts have concentrated on the producotin of an Engineering Unit, incorporating the components for the first time into a flight-like configuration. We summarize the status of the development of the processes for the key components and the initial metrology results of the Engineering Unit.

Petre, Robert; Zhang, William W.; Content, David A.; Saha, Timo T.; Stewart, Jeff; Hair, Jason H.; Nguyen, Diep; Podgorski, William A.; Davis, William R., Jr.; Freeman, Mark D.; Cohen, Lester M.; Schattenburg, Mark L.; Heilmann, Ralf K.; Sun, Yanxia; Forest, Craig R.

2003-03-01

230

A Positional X-ray Instrumentation Test Stand For Beam-Line Experiments  

NASA Astrophysics Data System (ADS)

A multi-axis, motion controlled test stand has been built in the PSU 47 m X-ray beam-line for the purpose of testing X-ray instrumentation and mirrors using parallel rays. The test stand is capable of translation along two axes and rotation about two axes with motorized fine position control. The translation stages have a range of motion of 200 mm with a movement accuracy of ± 2.5 microns. Rotation is accomplished with a two-axis gimbal which can rotate 360° about one axis and 240° about another; movement with ± 35 arcsecond accuracy are achieved in both axes. The position and status are monitored using a LabView program. An XCalibr source with multiple target materials is used as an X-ray source and can produce multiple lines between 0.8 and 8 keV. Some sample spectra are shown from a Si-PIN diode detector. This system is well suited for testing X-ray mirror segments which are currently being developed.

Nikoleyczik, Jonathan; Prieskorn, Z.; Burrows, D. N.; Falcone, A.

2014-01-01

231

Instrumental limits to our knowledge of the X-ray sky  

NASA Astrophysics Data System (ADS)

In the last decade, performances of X-ray detectors have improved over all parameter spaces (throughput, energy and spatial resolution, timing). However, the quality of our science is only as good as the quality our instruments' calibration. Measurements of X-ray observables in celestial sources are increasingly limited by systematic rather then by statistical errors. Unfortunately, all attempts at defining X-ray "standard candles" have proven unsuccessful so far. The energy scale can be still absolutely calibrated through emission lines produced by atomic transitions in on-board or astrophysical calibration sources. Likewise, timing accuracy can be estimated using fast rotators such as the Crab pulsar. On the other hand, uncertainties at the level of the order of 10% (and more) affect the absolute flux calibration. These "cross-calibration" uncertainties are energy-dependent, thus implying uncertainties on spectral measurements. I present in this talk the calibration and cross-calibration status of historical and operational X-ray detectors. Efforts to monitor, document and improve the cross-calibration status are carried out primarily by the IACHEC (International Astronomical Consortium for High Energy Calibration: http://web.mit.edu/iachec/). I will also briefly discuss the impact that these uncertainties (may) have on fields as diverse as the measurements of spin in accreting black holes, and the determination of cosmological parameters through surveys of galaxy clusters.

Guainazzi, Matteo

2014-08-01

232

X-ray absorption spectroscopy of the cubic and hexagonal polytypes of zinc sulfide  

NASA Astrophysics Data System (ADS)

We investigate the sensitivity of x-ray absorption spectroscopy to cubic-hexagonal polytypism in which nearest-neighbor positions are virtually unchanged. Experimental spectra and multiple-scattering calculations are reported at the major absorption edges in the zinc-blende and wurtzite modifications of ZnS. We demonstrate that d-like unoccupied bands are preferentially affected, as only L-edge absorption is sensitive to this structural transition. The results allow near-edge x-ray absorption spectroscopy to be evaluated as a detection method for crystal structure modifications in nano-scale systems.

Gilbert, B.; Frazer, B. H.; Zhang, H.; Huang, F.; Banfield, J. F.; Haskel, D.; Lang, J. C.; Srajer, G.; Stasio, G. De

2002-12-01

233

Portable X-ray fluorescence instruments for the analysis of lead in paints.  

PubMed Central

In a study in the laboratories of the Chicago Board of Health, the results from determination of lead in paint films by X-ray fluorescence were compared with results from determination by atomic absorption. Portable instruments of three suppliers were used for X-ray fluorescence measurements. An improved version of one of these instruments was also tested. The results of X-ray fluorescence readings on painted card stock panels with one of these instruments compared satisfactorily with the results as determined by the atomic absorption method at levels below 10 mg of lead per square centimeter. Readings on multiple layers of these panels were additive and independent of the order of these panels. All four instruments were tested in the laboratory on painted surfaces from the walls of condemned buildings. The most recent version of each instrument gave a correlation coefficient of 0.96 or better for the linear regression of lead values in milligrams per square centimeter by atomic absorption against instrument readings. It was calculated that a reading of 3.2 or greater on any of the instruments would indicate with greater than 95 percent confidence that 1 mg or more of lead per square centimeter would be found when a sample of the paint was analyzed by atomic absorption. When the readings of one of the instruments showed lead to be absent, that result would inidcate with better than 95 percent confidence that less than 1 mg of lead per square centimeter would be found by the atomic absorption method. Portable X-ray fluorescence instruments can be used in situ to determine whether the walls of a building give readings for lead above the range of 0 to 3.2. Walls with readings above this range can be considered to have 1 mg or more of lead per square centimeter and would not be in conformance with the code of the City of Chicago. Samples would need to be taken for analysis in the laboratory by atomic absorption only from those walls with readings within the range of 0 to 3.2. Images p224-a 1. 2. 3.

Kaplan, E H; Lilley, M D; Schaefer, R F; Cade, B; Desai, A; Padva, A; Orbach, H G

1975-01-01

234

X-Ray Absorption Spectroscopy Determination of Oxidation States  

NASA Astrophysics Data System (ADS)

Introduction: The oxidation state of minor and trace elements in minerals from planetary materials can be used to directly probe the oxygen fugacity of the environment from which the minerals formed. For example, on the basis of existing oxygen fugacity determinations it has been suggested that the parent bodies of chondrites were > 30 km in diameter [1]. Petrogenetic models generally assume oxygen fugacities based on indirect evidence. The x-ray microprobe offers the capability to determine oxidation states for a large suite of elements in individual coexisting phases in conventional rock thin sections using the microXANES (X-ray Absorption Near Edge Structure) technique. Recent Results: Initial research has concentrated on transition metals particularly Cr. The results on Cr oxidation state for olivine and pyroxene from mare basalts 15555 [2] showed that olivine contains predominately divalent Cr while pyroxene accommodates Cr mainly in trivalent state. Similar results for olivine from kimberlitic diamonds showed a mixture of the two states [3]. These results suggest that the terrestrial olivine crystallized in a more oxidizing environment than the lunar olivine and that divalent chromium is a ubiquitous component of olivine crystallized under reducing conditions. Calibration of the method in terms of oxygen fugacity requires the analysis of synthetic olivine crystallized from melts of appropriate composition at controlled fO(sub)2 [4]. MicroXANES analyses of Fe surprisingly suggested that Fe in plagioclase from lunar anorthosite 15415 is more oxidized than that in plagioclase from Stillwater anorthosites and shergottites [5]. Recently, iron oxide specimens were analyzed, specifically, magnetite (Fe3O4), hematite (Fe2O3) and altered magnetites (i.e., magnetites suspected of containing substantial alteration to hematite). The results showed that the altered magnetites are roughly equal mixtures of magnetite and hematite [6]. Future Research: The work on lunar olivines in lunar basalts is being extended to lunar olivines in highlands rocks. Oxygen fugacities of the early lunar magmas will be compared with those of the latter mare systems. Determinations of Cr oxidation state in olivine from carbonaceous meteorites are also being pursued but the Cr content of olivine from primitive meteorites is close to current detection limit with microXANES (about 10 ppm). MicroXANES will also provide valuable information on the oxidation states of transition elements in primitive interplanetary dust particles (IDPs). Preliminary results on one IDP indicated that Fe was in both the divalent and trivalent states and the shape of the spectrum is inconsistent with an oxide host. This technique will also be useful in estimating magnetite content in heated IDPs. Iron oxidation states of SNC meteorites and other achondrites will be valuable in constraining the oxygen fugacity of igneous planetary systems. Measurements of Ti^3+, Ti^4+, V^2+ and V^3+ in the constituent phases of CAIs will help to constrain the chemical history of materials that formed in the early solar nebula. The next generation synchrotron source, the Advanced Photon Source at Argonne National Laboratory, will be available for use by planetary scientists in 1996 and will extend these techniques to 1 ppm detection limits and 1 micrometer spatial resolution. References: [1] Rubin A. E. et al. (1988) In Meteorites and the Early Solar System, 488-511. [2] Sutton S. R. et al. (1993) GCA, 57-2, 461-468. [3] Sutton S. R. et al. (1993) LPS XXIV, 1383- 1384. [4] Hanson B. Z. and Delano J. W. (1992) LPS XXIII, 481- 482. [5] Delaney J. S. et al. (1992) LPS XXIII, 299-300. [6] Sutton S. R. et al. (1993) LPS XXIV, 1385-1386.

Bajt, S.; Sutton, S. R.; Smith, J. V.

1993-07-01

235

CdZnTe detector in mammographic x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

A CdZnTe (CZT) detector was utilized in mammographic x-ray spectroscopy under clinical conditions. First, the detector response was investigated using ?-rays from 241Am. The escape of secondary (Compton scattered and K fluorescent) x-rays and tailing due to carrier trapping were minor in the mammographic energy range. In addition, the transmission of primary x-rays was minimal from the results calculated using the mass attenuation coefficients of CZT. Therefore, spectral distortion in this energy range was expected to be negligible. Secondly, x-ray spectroscopy was carried out with the CZT detector. The measured spectra were in good agreement with the spectra obtained with the Compton-scatter method with a high-purity germanium detector. Moreover, the half-value layers (HVLs) calculated from the CZT spectra were consistent with the HVLs measured with an ionization chamber. The results indicate that a CZT detector can be utilized in mammographic x-ray spectroscopy without any corrections.

Miyajima, Satoshi; Imagawa, Kotaro

2002-11-01

236

Design of a 3-Stage ADR for the Soft X-Ray Spectrometer Instrument on the Astro-H Mission.  

National Technical Information Service (NTIS)

The Japanese Astro-H mission will include the Soft X-ray Spectrometer (SXS) instrument, whose 36-pixel detector array of ultra-sensitive x-ray microcalorimeters requires cooling to 50 mK. This will be accomplished using a 3-stage adiabatic demagnetization...

D. C. Wegel E. R. Canavan M. J. DiPirro M. O. Kimball P. J. Shirron

2011-01-01

237

X-ray fluorescence-spectometer\\/diffractometer for future lunar lander\\/rover mission  

Microsoft Academic Search

A miniaturized scientific instrument is being developed for a Japanese future lunar lander and rover mission to perform both of X-ray fluorescence (XRF) spectroscopy and X ray diffractometry (XRD). Onboard micro X ray tube with a fine focused-- collimator generates primary X-rays that excites fluorescence X rays characteristic- to component elements of the targeted sample and, at the same time,

K. Shirai; M. Aoki; S. Ito; T. Okada; Y. Yamamoto; T. Arai; K. Akagawa; M. Kato

2002-01-01

238

Cross sections with magnetic sublevels of He-like ions for polarized x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

In fast-ignition plasma, energy transport in dense plasma is one of the critical issues. The fast-ignition plasma emits polarized x-rays since the VDF of generated fast electron is anisotropic VDF. Spectroscopy of polarized x-ray is a useful diagnostics for studying the VDF of fast electrons. The time- dependent collisional-radiative atomic kinetics model was developed to analyze the experimental results of polarized Cl-He ? line [1]. To examine the model calculation, the cross sections with magnetic sublevels of He-like Cl and Cu ions were calculated [2]. The calculated cross sections with magnetic sublevels for He-like ions will be discussed for polarized x- ray spectroscopy in the ultrahigh-intense laser (10^17 10^ 20 W/cm^2). [1] T. Kai, et al., HEDP 3, 131 (2007); T. Kawamura et al., submitted. [2] T. Kai, et al., PRA 75, 012703 (2007). ibit, 75, 062710 (2007).

Kai, T.; Kawamura, T.; Nakazaki, S.; Inubushi, Y.; Nishimura, H.; Okano, Y.; Nakamura, T.; Johzaki, T.; Nagatomo, H.; Fujioka, S.; Mima, K.

2007-11-01

239

Surface Dynamics of Block Copolymer Films by X-ray Photon Correlation Spectroscopy  

SciTech Connect

We investigated the structure and dynamics of supported block copolymer films of poly(styrene)-b-poly(dimethylsiloxane)(PS-b-PDMS) in the spherical phase by x-ray photon correlation spectroscopy (XPCS) in grazing angle geometry. The temperature range studied was between 160 deg. and 210 deg. C, much higher than glass transition temperature (Tg), with thickness from 40 nm to 600 nm. Using x-ray reflectivity and x-ray photoelectron spectroscopy (XPS), we found that the PDMS-rich layer near the surface appeared at a temperature higher than Tg. Universal scaling of the dynamics, even with the bilayer model, was observed. From the fitting with the bilayer model, viscosities from both layers were obtained. The results from the surface dynamics are compared with the theory of overdamped thermal capillary waves on thin films.

Song, Sanghoon; Cha, Wonsuk; Lee, Heeju; Li, Xiaolong; Kim, Hyunjung [Department of Physics and Interdisciplinary Program of Integrated Biotechnology, Sogang University, Seoul (Korea, Republic of); Jiang, Zhang [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois (United States); Department of Physics, University of California San Diego, La Jolla, California (United States); Narayanan, Suresh [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois (United States); Ruehm, Adrian [Max Planck Institute for Metal Research, Stuttgart (Germany); Sinha, S. K. [Department of Physics, University of California San Diego, La Jolla, California (United States)

2009-04-19

240

X-ray spectroscopy of highly-charged heavy ions at FAIR  

NASA Astrophysics Data System (ADS)

In the current contribution, we give an overview of the envisioned X-ray spectroscopy program within the atomic physics research collaboration SPARC (Stored Particle Atomic Research Collaboration) at FAIR (Facility for Antiproton and Ion Research). These activities comprise, among others, the investigation of relativistic collision dynamics, electron correlation in the presence of strong fields, the test of Quantum Electrodynamics in extremely strong electromagnetic fields, and ideas to test the predictions of fundamental theories besides Quantum Electrodynamics. The state of the art X-ray spectroscopy will be of key importance for realization of these challenging goals. The world-wide unique experimental conditions and opportunities offered by the future FAIR facility will be combined with advanced X-ray detection devices, i.e. large-area, segmented solid-state detectors, high-resolution crystal spectrometers, calorimetric detectors etc.

Gumberidze, A.; Stöhlker, Th.; Beyer, H. F.; Bosch, F.; Bräuning-Demian, A.; Hagmann, S.; Kozhuharov, C.; Kühl, Th.; Mann, R.; Indelicato, P.; Quint, W.; Schuch, R.; Warczak, A.

2009-01-01

241

Recent advances in soft x-ray scattering instrumentation at the national synchrotron light source  

SciTech Connect

For the study of condensed matter systems x-ray scattering experiments are often the best choice as they have several desirable features including complete conservation of momentum in the incident and detected particles, well characterized initial and final electronic states, and insensitivity of photon transport to external electric and magnetic fields (as compared to photoelectrons for example). To extend these techniques to the soft x-ray region ({Dirac h}v < 1keV) the lack of suitable detectors, and the difficulties associated with performing scattering experiments in vacuum must be overcome. In this paper we provide details of our instrumental development program, and show some representative examples of experiments we have performed to date. 7 refs., 4 figs.

Johnson, E.D.; Kao, Chi-Chang; Hastings, J.B.

1991-01-01

242

Combination of Raman, Infrared, and X-Ray Energy-Dispersion Spectroscopies and X-Ray Diffraction to Study a Fossilization Process  

NASA Astrophysics Data System (ADS)

X-ray diffraction was combined with X-ray energy-dispersion, Fourier-transform infrared, and Raman spectroscopies to study the fossilization of a Cretaceous specimen of the plant Brachyphyllum castilhoi, a fossil from the Ipubi Formation, in the Araripe Sedimentary Basin, Northeastern Brazil. Among the possible fossilization processes, which could involve pyrite, silicon oxide, calcium oxide, or other minerals, we were able to single out pyritization as the central mechanism producing the fossil, more than 100 million years ago. In addition to expanding the knowledge of the Ipubi Formation, this study shows that, when combined with other experimental techniques, Raman spectroscopy is a valuable tool at the paleontologist's disposal.

de Sousa Filho, Francisco Eduardo; da Silva, João Hermínio; Feitosa Saraiva, Antônio Álamo; Brito, Deyvid Dennys S.; Viana, Bartolomeu Cruz; de Oliveira Abagaro, Bruno Tavares; de Tarso Cavalcante Freire, Paulo

2011-12-01

243

Stereochemistry Determination by Powder X-ray Diffraction Analysis and NMR Spectroscopy Residual Dipolar Couplings  

SciTech Connect

A matter of technique: For a new steroidal lactol, jaborosalactol 24 (1), isolated from Jaborosa parviflora, NMR spectroscopy residual dipolar couplings and powder X-ray diffraction analysis independently gave the same stereochemistry at C23-C26. Conventional NMR spectroscopic techniques, such as NOE and {sup 3}J coupling-constant analysis failed to unambiguously determine this stereochemistry.

Garcia, M.; Pagola, S; Navarro-Vasquez, A; Phillips, D; Gayathri, C; Krakauer, H; Stephens, P; Nicotra, V; Gil, R

2009-01-01

244

X-ray spectroscopy of highly-ionized atoms in an electron beam ion trap (EBIT)  

SciTech Connect

An Electron Beam Ion Trap at Lawrence Livermore National Laboratory is being used to produce and trap very-highly-charged-ions (q /le/ 70+) for x-ray spectroscopy measurements. Recent measurements of dielectronic recombination, electron impact excitation and transition energies are presented. 15 refs., 12 figs., 1 tab.

Marrs, R.E.; Bennett, C.; Chen, M.H.; Cowan, T.; Dietrich, D.; Henderson, J.R.; Knapp, D.A.; Levine, M.A.; Schneider, M.B.; Scofield, J.H.

1988-01-01

245

Passive Spectroscopy Bolometers, Grating- And X-Ray Imaging Crystal Spectrometers  

SciTech Connect

This tutorial gives a brief introduction into passive spectroscopy and describes the working principles of bolometers, a high-resolution grating spectrometer, and a novel X-ray imaging crystal spectrometer, which is of particular interest for profile measurements of the ion temperature and plasma rotation velocity on ITER and future burning plasma experiments.

Bitter, M; Hill, K W; Scott, S; Paul, S; Ince-Cushmann, A; Reinke, M; Rice, J; Beiersdorfer, P; Gu, M F; Lee, S G; Broennimann, C; Eikenberry, E F

2007-11-07

246

Application of x-ray absorption spectroscopy to the study of corrosion and inhibition  

SciTech Connect

X-ray absorption spectroscopy is a powerful technique for determination of valency and coordination. Measurements can be made in air or in situ under electrochemical control. The technique will be described and its application to the analysis of passive oxide films, corrosion products, and inhibitors will be reviewed.

Davenport, A.J.; Isaacs, H.S.

1991-01-01

247

Passive Spectroscopy Bolometers, Grating- And X-ray Imaging Crystal Spectrometers  

SciTech Connect

This tutorial gives a brief introduction into passive spectroscopy and describes the working principles of bolometers, a high-resolution grating spectrometer, and a novel X-ray imaging crystal spectrometer, which is also of particular interest for profile measurements of the ion temperature and plasma rotation velocity on ITER and future burning plasma experiments.

Bitter, M.; Hill, K. W.; Scott, S.; Paul, S. [Princeton Plasma Physics Laboratory, Princeton, NJ, 08543 (United States); Ince-Cushman, A.; Reinke, M.; Rice, J. E. [Plasma Science and Fusion Center, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Beiersdorfer, P.; Gu, M. F. [Lawrence Livermore national Laboratory, Livermore, CA 94550-9234 (United States); Lee, S. G. [Korea Basic Science Institute, Taejeon 305-333 (Korea, Republic of); Broennimann, Ch.; Eikenberry, E. F. [Paul Scherrer Institut, CH5232 Villigen-PSI (Switzerland)

2008-03-12

248

K- and L-shell x-ray spectroscopy of indirectly driven implosions.  

National Technical Information Service (NTIS)

Time resolved x-ray spectroscopy is used to study the implosion of indirectly driven inertial confinement fusion capsules on the Nova laser. Through the use of high-Z dopants (Ar and Xe) in the fuel, measurements of the peak temperature, from emission lin...

B. A. Hammel

1992-01-01

249

Structure of the manganese complex in photosystem II: insights from X-ray spectroscopy.  

PubMed Central

We have used Mn K-edge absorption and Kbeta emission spectroscopy to determine the oxidation states of the Mn complex in the various S states. We have started exploring the new technique of resonant inelastic X-ray scattering spectroscopy; this technique can be characterized as a Raman process that uses K-edge energies (1s to 4p, ca. 6550 eV) to obtain L-edge-like spectra (2p to 3d, ca. 650 eV). The relevance of these data to the oxidation states and structure of the Mn complex is presented. We have obtained extended X-ray absorption fine structure data from the S(0) and S(3) states and observed heterogeneity in the Mn-Mn distances leading us to conclude that there may be three rather than two di-mu-oxo-bridged units present per tetranuclear Mn cluster. In addition, we have obtained data using Ca and Sr X-ray spectroscopy that provide evidence for a heteronuclear Mn-Ca cluster. The possibility of three di-mu-oxo-bridged Mn-Mn moieties and the proximity of Ca is incorporated into developing structural models for the Mn cluster. The involvement of bridging and terminal O ligands of Mn in the mechanism of oxygen evolution is discussed in the context of our X-ray spectroscopy results.

Yachandra, Vittal K

2002-01-01

250

Zinc ligands in the metal hyperaccumulator Thlaspi caerulescens as determined using X-ray absorption spectroscopy  

Microsoft Academic Search

Using the noninvasive technique of X-ray absorption spectroscopy (XAS), the authors have been able to determine the ligand environment of Zn in different tissues of the Zn-hyperaccumulator Thlaspi caerulescens. The majority of intracellular Zn in roots of T. caerulescens was found to be coordinated with histidine. In the xylem sap Zn was found to be transported mainly as the free

David E. Salt; Roger C. Prince; Alan J. M. Baker; Ilya Raskin; Ingrid J. Pickering

1999-01-01

251

X-Ray Absorption near Edge Structure Spectroscopy of Nanodiamonds from the Allende Meteorite  

NASA Technical Reports Server (NTRS)

Carbon X-ray Absorption Near Edge Structure Spectroscopy shows Allende DM nanodiamonds have two pre-edge peaks, consistent with other small diamonds, but fail to show a diamond exciton which is seen in 3.6 nm diamond thin films.

Flynn, G. J.; Keller, L. P.; Hill, H.; Jacobsen, C.; Wirick, S.

2000-01-01

252

Quantitative Characterization of DNA Films by X-ray Photoelectron Spectroscopy.  

National Technical Information Service (NTIS)

We describe the use of self-assembled films of thiolated (dT)25 single-stranded DNA (ssDNA) on gold as a model system for quantitative characterization of DNA films by X-ray photoelectron spectroscopy (XPS). We evaluate the applicability of a uniform and ...

D. Y. Petrovykh H. Kimura-Suda L. J. Whitman M. J. Tarlov

2003-01-01

253

Evaluating Superconducting YBCO Film Properties Using X-Ray Photoelectron Spectroscopy (Postprint).  

National Technical Information Service (NTIS)

Initial results have been recently reported that suggest a potential correlation exists between the full-width-half-maximum (FWHM) of the Y(3d) peak obtained by x-ray photoelectron spectroscopy (XPS) and the critical current density a YBa2Cu3O7-x film can...

J. C. Tolliver J. T. Grant P. N. Barnes S. M. Mukhopadhyay T. J. Haugan

2012-01-01

254

Spectroscopy of 7 INTEGRAL X-ray sources (Chaty+, 2008)  

NASA Astrophysics Data System (ADS)

We performed an intensive study of a sample of thirteen INTEGRAL sources, through multi-wavelength optical to NIR photometric and spectroscopic observations, using EMMI and SofI instruments at the ESO-NTT telescope. We performed accurate astrometry and identified candidate counterparts for which we give the optical and NIR magnitudes. We detected many spectral lines allowing us to determine the spectral type of the companion star. We fitted with stellar black bodies the mid-infrared to optical spectral energy distributions of these sources. From the spectral analysis and SED fitting we identified the nature of the companion stars and of the binary systems. (1 data file).

Chaty, S.; Rahoui, F.; Foellmi, C.; Tomsick, J. A.; Rodriguez, J.; Walter, R.

2008-05-01

255

Resonant soft X-ray emission spectroscopy of liquids  

SciTech Connect

We present now a possible way to carry out soft-x-rayfluorescence spectroscopy of liquids. The liquid cell has a window toattain compatibility with UHV conditions of the spectrometer andbeamline, The synchrotron radiation enters the liquid cell through a 100nm-thick silicon nitride window and the emitted xrays exit through thesame window. This allows in particular liquid solid interfaces to bestudied. Such a liquid cell has been used to study the electronicstructure of a variety of systems ranging from water solutions ofinorganic salts and inertial drugs to nano materials and actinidecompounds in their wet conditions.

Guo, J.-H.; Augustsson, A.; Englund, C.-J.; Nordgren, J.

2004-10-27

256

Use of portable X-ray fluorescence instrument for bulk alloy analysis on low corroded indoor bronzes  

NASA Astrophysics Data System (ADS)

One of the most often used non-destructive methods for elemental analysis when performing field measurements on bronze sculptures is X-ray fluorescence (XRF) analysis based on portable instrumentation. However, when performing routine in-situ XRF analysis on corroded objects obtained results are sometimes considerably influenced by the corrosion surface products. In this work the suitability of portable XRF for bulk analysis of low corroded bronzes, which were initially precisely characterized using sophisticated and reliable laboratory methods, was investigated and some improvements in measuring technique and data processing were given. Artificially corroded bronze samples were analyzed by a portable XRF instrument using the same methodology and procedures as when performing in-situ analysis on real objects. The samples were first investigated using sophisticated complementary laboratory techniques: Scanning Electron Microscopy, Proton-Induced X-ray Emission Spectroscopy and Rutherford Backscattering Spectrometry, in order to gain precise information on the formation of the corrosion product layers and in-depth elemental profile of corrosion layers for different aging parameters. It has been shown that for corrosion layers of up to ca. 25 ?m a portable XRF can yield very accurate quantification results.

Šatovi?, D.; Desnica, V.; Fazini?, S.

2013-11-01

257

Set of instruments for solar EUV and soft X-ray monitoring onboard satellite Coronas-Photon  

NASA Astrophysics Data System (ADS)

Coronas-Photon mission is the third satellite of the Russian Coronas program on solar activity observation. The main goal of the "Coronas-Photon" is the study of solar hard electromagnetic radiation in the wide energy range from UV up to high energy gamma-radiation (2000MeV). Scientific payload for solar radiation observation consists of three types of instruments: Monitors (Natalya-2M, Konus-RF, RT-2, Penguin-M, BRM, PHOKA, Sphin-X, SOKOL spectral and timing measurements of full solar disk radiation have timing in flare/burst mode up to one msec. Instruments Natalya-2M, Konus-RF, RT-2 will cover the wide energy range of hard X-rays and soft gamma-rays (15keV to 2000MeV) and will together constitute the largest area detectors ever used for solar observations. Detectors of gamma-ray monitors are based on structured inorganic scintillators. For X-ray and EUV monitors the scintillation phoswich detectors, gas proportional counter, CdZnTe assembly and filter-covered Si-diodes are used. Telescope-spectrometer TESIS for imaging solar spectroscopy in X-rays has angular resolution up to 1arcsec in three spectral lines. Satellite platform and scientific payload is under construction to be launched in autumn 2008. Satellite orbit is circular with initial height 550km and inclination 82.5degrees. Accuracy of the spacecraft orientation to the Sun is better 3arcmin. In the report the capability of PHOKA, SphinX, SOKOL and TESIS as well as the observation program are described and discussed.

Kotov, Yury; Kochemasov, Alexey; Kuzin, Sergey; Kuznetsov, Vladimir; Sylwester, Janusz; Yurov, Vitaly

258

Thickness Variation of HfO2 Films Under Post-Deposition Annealing Investigated By X-ray Reflectivity and X-ray Photoelectron Spectroscopy  

NASA Astrophysics Data System (ADS)

As transistor feature sizes scaling down, the ultra-thin HfO2 high-k dielectric has been used to replace SiO2 for the gate dielectric to meet a better EOT for good electric performances. X-ray Reflectivity (XRR) is an accurate instrument to analyze the ultra-thin HfO2 films based on an appropriate material structure model in the data analysis. However, the material structure model is not easily defined for the ultra-thin HfO2 films, especially when interfaces between layers are changed under thermal annealing. In this work, the interfaces between layers of the ultra-thin HfO2 films were investigated at the as-deposited condition (ASD) and post-deposition annealing (PDA) processes. X-ray Photoelectron Spectroscopy (XPS) was used to evaluate the layer structures, which were post-annealed up to 1000 °C using furnaces in the Ar ambiances. The experimental results and analysis showed that layer thicknesses, crystal phases and chemical structures of the ultra-thin HfO2 films were significantly dependent on annealing temperatures. Accordingly, the interface with increasing annealing temperatures was broadened due to the existence of HfSixOy. As a result, a four-layer material structure model of HfO2 (low-density)/HfO2/HfSixOy/SiO2/Si-substrate based on XPS analysis was constructed to significantly improve the XRR fitting process with genetic algorithm (GA). The structure analysis of the XRR spectra using the modified material structure model from the XPS analysis confirmed the interfacial broadening induced by the post-deposition annealing.

Chang, Yong-Qing; Fu, Wei-En

2011-11-01

259

Time and space resolved spectroscopy of x-ray laser experiments  

SciTech Connect

We report experimental data from one of the first of this new generation of instruments designed specifically for laboratory x-ray laser diagnosis. Representative TGSS-EM data are presented from three different x-ray laser inversion schemes: collisional excitation of neon-like selenium (lambda approx. = 206, 209A); resonant photoexcitation of hydrogen-like fluorine (lambda = 81A); and recombination of hydrogen-like magnesium (lambda approx. = 130A). The data illustrate the measurement capabilities of the TGSS-EM and provide insight to the dynamics and emission characteristics of this new class of laser produced plasmas.

Ceglio, N.M.

1986-04-01

260

Theoretical standards in x-ray spectroscopies. Annual progress report, 1991--1992  

SciTech Connect

We propose to extend our state-of-the-art, ab initio XAFS (X-ray absorption fine structure) codes, FEFF. Our current work has been highly successful in achieving accurate, user-friendly XAFS standards, exceeding the performance of both tabulated standards and other codes by a considerable margin. We now propose to add the capability to treat more complex materials. This includes multiple-scattering, polarization dependence, an approximate treatment of XANES (x-ray absorption near edge structure), and other improvements. We also plan to adapt FEFF to other spectroscopies, e.g. photoelectron diffraction (PD) and diffraction anomalous fine structure (DAFS).

Not Available

1992-09-01

261

Energy-dispersive X-ray absorption spectroscopy at LNLS: investigation on strongly correlated metal oxides.  

PubMed

An energy-dispersive X-ray absorption spectroscopy beamline mainly dedicated to X-ray magnetic circular dichroism (XMCD) and material science under extreme conditions has been implemented in a bending-magnet port at the Brazilian Synchrotron Light Laboratory. Here the beamline technical characteristics are described, including the most important aspects of the mechanics, optical elements and detection set-up. The beamline performance is then illustrated through two case studies on strongly correlated transition metal oxides: an XMCD insight into the modifications of the magnetic properties of Cr-doped manganites and the structural deformation in nickel perovskites under high applied pressure. PMID:20029117

Cezar, Júlio C; Souza-Neto, Narcizo M; Piamonteze, Cínthia; Tamura, Edilson; Garcia, Flávio; Carvalho, Edson J; Neueschwander, Régis T; Ramos, Aline Y; Tolentino, Hélio C N; Caneiro, Alberto; Massa, Nestor E; Martinez-Lope, Maria Jesus; Alonso, Jose Antonio; Itié, Jean Paul

2010-01-01

262

Two-dimensional stimulated resonance Raman spectroscopy of molecules with broadband x-ray pulses  

PubMed Central

Expressions for the two-dimensional stimulated x-ray Raman spectroscopy (2D-SXRS) signal obtained using attosecond x-ray pulses are derived. The 1D- and 2D-SXRS signals are calculated for trans-N-methyl acetamide (NMA) with broad bandwidth (181 as, 14.2 eV FWHM) pulses tuned to the oxygen and nitrogen K-edges. Crosspeaks in 2D signals reveal electronic Franck-Condon overlaps between valence orbitals and relaxed orbitals in the presence of the core-hole.

Biggs, Jason D.; Zhang, Yu; Healion, Daniel; Mukamel, Shaul

2012-01-01

263

Testing LaMgAl11O19 crystal for X-ray spectroscopy  

SciTech Connect

We investigated the properties of the rare earth crystal LaMgAl{sub 11}O{sub 19} and its application to soft X-ray spectroscopy. Its relative reflectivity and half width rocking curve were measured to up to the reflection order of 28. In addition, a comparative measurement of the iron L-shell soft X-ray line emission was made on the EBIT-I Livermore electron beam ion trap by fielding the LaMgAl{sub 11}O{sub 19} crystal side by side with a rubidium hydrogen phthalate crystal in a flat crystal spectrometer. From these measurements, reflectivity and spectral resolving power were determined.

Chen, H; Beiersdorfer, P; Baronova, E; Kalashnikova, I; Stepanenko, M

2004-03-31

264

X-ray excited optical luminescence, photoluminescence, photostimulated luminescence and x-ray photoemission spectroscopy studies on BaFBr:Eu  

NASA Astrophysics Data System (ADS)

The results of x-ray excited optical luminescence (XEOL), photoluminescence (PL), photostimulated luminescence (PSL) and x-ray photoemission spectroscopy (XPS) studies on the x-ray storage phosphor BaFBr:Eu are presented in this paper. Analyses of XEOL, PL and PSL spectra reveal features corresponding to the transitions from 0953-8984/9/22/027/img9 to 0953-8984/9/22/027/img10 configurations in different site symmetries of 0953-8984/9/22/027/img11. Increasing x-ray dose is seen to lead to a red shift in the maximum of the PL excitation spectrum for the 391 nm emission. The XEOL and XPS spectra do not show any signature of 0953-8984/9/22/027/img12 in the samples studied by us, directly raising doubts about the model of Takahashi et al in which 0953-8984/9/22/027/img11 is expected to ionize to 0953-8984/9/22/027/img12 upon x-ray irradiation and remain stable until photostimulation. XEOL and PSL experiments with simultaneous x-ray irradiation and He - Ne laser excitation as well as those with sequential x-ray irradiation and laser stimulation bring out the competition between the F centre population and depopulation rates. A time scale 0953-8984/9/22/027/img15 - 2 s, possibly related to the process of production of the electron/hole traps themselves, during x-ray irradiation, is observed. Relaxation of these traps upon photostimulation is also seen.

Subramanian, N.; Kesavamoorthy, R.; Rajan, K. Govinda; Yousuf, Mohammad; Bera, Santanu; Narasimhan, S. V.

1997-06-01

265

Quantification of total element concentrations in soils using total X-ray fluorescence spectroscopy (TXRF).  

PubMed

Total X-ray fluorescence spectroscopy (TXRF) determines concentrations of major and trace elements in multiple media. We developed and tested a method for the use of TXRF for direct quantification of total element concentrations in soils using an S2 PICOFOX™ spectrometer (Bruker AXS Microanalysis GmbH, Germany). We selected 15 contrasting soil samples from across sub-Saharan Africa for element analysis to calibrate the instrument against concentrations determined using the inductively coupled plasma-mass spectroscopy (ICP-MS) standard method. A consistent underestimation of element concentrations using TXRF compared to ICP-MS reference analysis occurred, indicating that spectrometer recalibration was required. Single-element recalibration improved the TXRF spectrometer's sensitivity curve. Subsequent analysis revealed that TXRF determined total element concentrations of Al, K, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, and Ga accurately (model efficacy/slope close to 1:1 line, and R(2)>0.80) over a wide range of soil samples. Other elements that could be estimated with an acceptable precision (R(2)>0.60) compared with ICP-MS although generally somewhat under- or overestimated were P, Ca, As, Rb, Sr, Y, Pr, Ta and Pb. Even after recalibration, compared to ICP-MS the TXRF spectrometer produced underestimations for elements Na, Mg, Ba, Ce, Hf, La, Nd, W and Sm and overestimations for elements Bi, Tl and Zr. We validated the degree of accuracy of the TXRF analytical method after recalibration using an independent set of 20 soil samples. We also tested the accuracy of the analysis using 2 multi-element standards as well as the method repeatability on replicate samples. The resulting total element concentration repeatability for all elements analyzed were within 10% coefficient of variability after the instrument recalibration except for Cd and Tl. Our findings demonstrate that TXRF could be used as a rapid screening tool for total element concentrations in soils assuming that sufficient calibration measures are followed. PMID:23831788

Towett, Erick K; Shepherd, Keith D; Cadisch, Georg

2013-10-01

266

A study of an iron dextran complex by Mössbauer spectroscopy and x-ray diffraction  

Microsoft Academic Search

An injectable iron dextran complex used as a hematinic has been studied using Mössbauer spectroscopy (18–295 K) and x-ray powder diffraction. The iron is 100% high-spin Fe3+ as determined by Mössbauer spectroscopy. While different samples of the complex showed different magnetic ordering temperatures, all the spectra can be adequately fitted to a distribution of doublets at room temperature and to

Emma M. Coe; Lawrence H. Bowen; Robert D. Bereman; J. Alexander Speer; William T. Monte; Laurie Scaggs

1995-01-01

267

Instrumentation for a next-generation x-ray all-sky monitor  

SciTech Connect

We have proposed an x-ray all-sky monitor for a small satellite mission that will be ten times more sensitive than past monitors and that opens up a new band of the soft x-ray spectrum (0.1-3.0 keV) for study. We discuss three approaches to the construction of the optics. The first method, well within the reach of existing technology, is to approximate the lobster-eye geometry by building crossed arrays of planar reflectors, this gives great control over the reflecting surface but is limited in terms of resolution at the baseline 4 arc minute level. The second method is to use microchannel plates; this technology has the potential to greatly exceed the baseline resolution and sensitivity but is yet to be fully demonstrated. The third method, while still in its infancy, may yet prove to be the most powerful; this approach relies on photolithography to expose a substrate that can then be developed and replicated. The scientific case for this mission is almost too broad to state here. The instrument we describe will allow investigation of the long term light curves of thousands of AGN, it will detect thousands of transients, including GRBs and type II supernova, and the stellar coronae of hundreds of the brightest x-ray stars can be monitored. In addition the classical objectives of all-sky monitors--long-term all-sky archive and watchdog alert to new events--will be fulfilled at an unprecedented level. We also note that by opening up a little-explored band of the x-ray sky the opportunity for new discovery is presented. A satisfying example of entering new territory while still retaining the guarantee of expanding the domain of existing research.

Peele, A. G. [Code 662, Laboratory for High Energy Astrophysics, Goddard Space Flight Center, Greenbelt, Maryland 20771 (United States)

1999-12-15

268

Energy-dispersive X-ray emission spectroscopy using an X-ray free-electron laser in a shot-by-shot mode.  

PubMed

The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this "probe-before-destroy" approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. K?(1,3) XES spectra of Mn(II) and Mn(2)(III,IV) complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to >100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II. PMID:23129631

Alonso-Mori, Roberto; Kern, Jan; Gildea, Richard J; Sokaras, Dimosthenis; Weng, Tsu-Chien; Lassalle-Kaiser, Benedikt; Tran, Rosalie; Hattne, Johan; Laksmono, Hartawan; Hellmich, Julia; Glöckner, Carina; Echols, Nathaniel; Sierra, Raymond G; Schafer, Donald W; Sellberg, Jonas; Kenney, Christopher; Herbst, Ryan; Pines, Jack; Hart, Philip; Herrmann, Sven; Grosse-Kunstleve, Ralf W; Latimer, Matthew J; Fry, Alan R; Messerschmidt, Marc M; Miahnahri, Alan; Seibert, M Marvin; Zwart, Petrus H; White, William E; Adams, Paul D; Bogan, Michael J; Boutet, Sébastien; Williams, Garth J; Zouni, Athina; Messinger, Johannes; Glatzel, Pieter; Sauter, Nicholas K; Yachandra, Vittal K; Yano, Junko; Bergmann, Uwe

2012-11-20

269

Energy-dispersive X-ray emission spectroscopy using an X-ray free-electron laser in a shot-by-shot mode  

PubMed Central

The ultrabright femtosecond X-ray pulses provided by X-ray free-electron lasers open capabilities for studying the structure and dynamics of a wide variety of systems beyond what is possible with synchrotron sources. Recently, this “probe-before-destroy” approach has been demonstrated for atomic structure determination by serial X-ray diffraction of microcrystals. There has been the question whether a similar approach can be extended to probe the local electronic structure by X-ray spectroscopy. To address this, we have carried out femtosecond X-ray emission spectroscopy (XES) at the Linac Coherent Light Source using redox-active Mn complexes. XES probes the charge and spin states as well as the ligand environment, critical for understanding the functional role of redox-active metal sites. K?1,3 XES spectra of MnII and Mn2III,IV complexes at room temperature were collected using a wavelength dispersive spectrometer and femtosecond X-ray pulses with an individual dose of up to >100 MGy. The spectra were found in agreement with undamaged spectra collected at low dose using synchrotron radiation. Our results demonstrate that the intact electronic structure of redox active transition metal compounds in different oxidation states can be characterized with this shot-by-shot method. This opens the door for studying the chemical dynamics of metal catalytic sites by following reactions under functional conditions. The technique can be combined with X-ray diffraction to simultaneously obtain the geometric structure of the overall protein and the local chemistry of active metal sites and is expected to prove valuable for understanding the mechanism of important metalloproteins, such as photosystem II.

Alonso-Mori, Roberto; Kern, Jan; Gildea, Richard J.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Lassalle-Kaiser, Benedikt; Tran, Rosalie; Hattne, Johan; Laksmono, Hartawan; Hellmich, Julia; Glockner, Carina; Echols, Nathaniel; Sierra, Raymond G.; Schafer, Donald W.; Sellberg, Jonas; Kenney, Christopher; Herbst, Ryan; Pines, Jack; Hart, Philip; Herrmann, Sven; Grosse-Kunstleve, Ralf W.; Latimer, Matthew J.; Fry, Alan R.; Messerschmidt, Marc M.; Miahnahri, Alan; Seibert, M. Marvin; Zwart, Petrus H.; White, William E.; Adams, Paul D.; Bogan, Michael J.; Boutet, Sebastien; Williams, Garth J.; Zouni, Athina; Messinger, Johannes; Glatzel, Pieter; Sauter, Nicholas K.; Yachandra, Vittal K.; Yano, Junko; Bergmann, Uwe

2012-01-01

270

IN SITU STUDIES OF CORROSION USING X-RAY ABSORPTION NEAR SPECTROSCOPY (XANES)  

SciTech Connect

Applications of x-ray absorption near-edge spectroscopy (XANES) and the design of cells for in situ corrosion studies are reviewed. Passive films studies require very thin metal or alloy layers be used having a thickness of the order of the films formed because of penetration of the x-ray beam into the metal substrate. The depth of penetration in water also limits the thickness of solutions that can be used because of water reduces the x-ray intensity. Solution thickness must also be limited in studies of conversion layer formation studies because the masking of the Cr in solution. Illustrative examples are taken from the anodic behavior of Al-Cr alloys, the growth of passive films on Fe and stainless steels, and the formation of chromate conversion layers on Al.

ISAACS, H.S.; SCHMUKI, P.; VIRTANEN, S.

2001-03-25

271

Capturing molecular structural dynamics by 100 ps time-resolved X-ray absorption spectroscopy  

PubMed Central

An experimental set-up for time-resolved X-ray absorption spectroscopy with 100?ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. The X-ray positional active feedback to crystals in a monochromator combined with a figure-of-merit scan of the laser beam position has been utilized as an essential tool to stabilize the spatial overlap of the X-ray and laser beams at the sample position. As a typical example, a time-resolved XAFS measurement of a photo-induced spin crossover reaction of the tris(1,10-phenanthrorine)iron(II) complex in water is presented.

Sato, Tokushi; Nozawa, Shunsuke; Ichiyanagi, Kohei; Tomita, Ayana; Chollet, Matthieu; Ichikawa, Hirohiko; Fujii, Hiroshi; Adachi, Shin-ichi; Koshihara, Shin-ya

2009-01-01

272

X-ray spectroscopy of Cu impurities on NSTX and comparison with Z-pinch plasmas  

SciTech Connect

X-ray spectroscopy of mid-Z metal impurities is important in the study of tokamak plasmas and may reveal potential problems if their contribution to the radiated power becomes substantial. The analysis of the data from a high-resolution x-ray and extreme ultraviolet grating spectrometer, XEUS, installed on NSTX, was performed focused on a detailed study of x-ray spectra in the range 7-18 A. These spectra include not only commonly seen iron spectra but also copper spectra not yet employed as an NSTX plasma impurity diagnostic. In particular, the L-shell Cu spectra were modeled and predictions were made for identifying contributions from various Cu ions in different spectral bands. Also, similar spectra, but from much denser Cu plasmas produced on the UNR Z-pinch facility and collected using the convex-crystal spectrometer, were analyzed and compared with NSTX results.

Safronova, A. S.; Ouart, N. D.; Kantsyrev, V. L.; Cox, P. G.; Shlyaptseva, V.; Williamson, K. M. [University of Nevada, Reno, Nevada 89557 (United States); Lepson, J. K. [Space Sciences Laboratory, Berkeley, California 94720 (United States); Beiersdorfer, P. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Stratton, B.; Bitter, M. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States)

2010-10-15

273

Sulfur K-edge X-ray absorption spectroscopy of petroleum asphaltenes and model compounds  

SciTech Connect

The utility of sulfur K-edge X-ray absorption spectroscopy for the determination and quantification of sulfur forms in petroleum asphaltenes has been investigated. Both X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) spectra were obtained for a selected group of model compounds and for several petroleum asphaltene samples. For the model compounds the sulfur XANES was found to vary widely from compound to compound and to provide a fingerprint for the form of sulfur involved. The use of third derivatives of the spectra enabled discrimination of mixtures of sulfidic and thiophenic model compounds and allowed approximate quantification of the amount of each component in the mixtures and in the asphaltene samples. These results represent the first demonstration that nonvolatile sulfur forms can be distinguished and approximately quantified by direct measurement.

George, G.N.; Gorbaty, M.L. (Exxon Research and Engineering Co., Annandale, NJ (USA))

1989-04-26

274

Capturing molecular structural dynamics by 100 ps time-resolved X-ray absorption spectroscopy.  

PubMed

An experimental set-up for time-resolved X-ray absorption spectroscopy with 100 ps time resolution at beamline NW14A at the Photon Factory Advanced Ring is presented. The X-ray positional active feedback to crystals in a monochromator combined with a figure-of-merit scan of the laser beam position has been utilized as an essential tool to stabilize the spatial overlap of the X-ray and laser beams at the sample position. As a typical example, a time-resolved XAFS measurement of a photo-induced spin crossover reaction of the tris(1,10-phenanthrorine)iron(II) complex in water is presented. PMID:19096182

Sato, Tokushi; Nozawa, Shunsuke; Ichiyanagi, Kohei; Tomita, Ayana; Chollet, Matthieu; Ichikawa, Hirohiko; Fujii, Hiroshi; Adachi, Shin Ichi; Koshihara, Shin Ya

2009-01-01

275

Transformation of nanodiamond into carbon onions: A comparative study by high-resolution transmission electron microscopy, electron energy-loss spectroscopy, x-ray diffraction, small-angle x-ray scattering, and ultraviolet Raman spectroscopy  

Microsoft Academic Search

The structural properties of both nanodiamond particles synthesized by detonation and the products of their transformation into carbon onions via vacuum annealing at 1000 and 1500 °C have been studied using high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy, x-ray diffraction (XRD), small-angle x-ray scattering (SAXS), and Raman spectroscopy. The advantages of UV Raman spectroscopy over visible Raman spectroscopy for

Oleksandr O. Mykhaylyk; Yurii M. Solonin; David N. Batchelder; Rik Brydson

2005-01-01

276

An x-ray absorption spectroscopy study of Mo oxidation in Pb at elevated temperatures  

SciTech Connect

The corrosion of fuel cladding and structural materials by lead and lead-bismuth eutectic in the liquid state at elevated temperatures is an issue that must be considered when designing advanced nuclear systems and high-power spallation neutron targets. In this work, lead corrosion studies of molybdenum were performed to investigate the interaction layer as a function of temperature by X-ray absorption spectroscopy. In situ X-ray absorption measurements on a Mo substrate with a 3-6 {micro}m layer of Pb deposited by thermal evaporation were performed at temperatures up to 900 C and at a 15{sup o} angle to the incident X-rays. The changes in the local atomic structure of the corrosion layer are visible in the difference extended X-ray absorption fine structure and the linear combination fitting of the X-ray absorption near-edge structure to as-deposited molybdenum sample and molybdenum oxide (MoO{sub 2} and MoO{sub 3}) standards. The data are consistent with the appearance of MoO{sub 3} in an intermediate temperature range (650-800 C) and the more stable MoO{sub 2} phase dominating at high and low temperatures.

Liu, Shanshan; Olive, Daniel; Terry, Jeff; Segre, Carlo U.; (IIT)

2009-06-30

277

X-ray spectroscopy of the mixed morphology supernova remnant W 28 with XMM-Newton  

NASA Astrophysics Data System (ADS)

We report on spatially resolved X-ray spectroscopy of the north-eastern part of the mixed morphology supernova remnant (SNR) W 28 with XMM-Newton. The observed field of view includes a prominent and twisted shell emission forming the edge of this SNR as well as part of the center-filled X-ray emission brightening toward the south-west edge of the field of view. The shell region spectra are in general represented by an optically thin thermal plasma emission in collisional ionization equilibrium with a temperature of ˜ 0.3 keV and a density of ˜ 10 cm-3, which is much higher than the density obtained for inner parts. In contrast, we detected no significant X-ray flux from one of the TeV ?-ray peaks with an upper-limit flux of 2.1 × 10-14 erg cm-2 s-1 in the 2-10 keV band. The large flux ratio of TeV to X-ray, larger than 16, and the spatial coincidence of the molecular cloud and the TeV ?-ray emission site indicate that the TeV ?-ray of W 28 is ?0-decay emission originating from collisions between accelerated protons and molecular cloud protons. Comparing the spectrum in the TeV band and the X-ray upper limit, we obtained a weak upper limit on the magnetic field strength B ? 1500 ?G.

Nakamura, Ryoko; Bamba, Aya; Ishida, Manabu; Yamazaki, Ryo; Tatematsu, Ken'ichi; Kohri, Kazunori; Pühlhofer, Gerd; Wagner, Stefan J.; Sawada, Makoto

2014-06-01

278

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  

Microsoft Academic Search

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

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

2008-01-01

279

Performance and status of beamline BL8 at SLRI for X-ray absorption spectroscopy.  

PubMed

Beamline BL8 of the Synchrotron Light Research Institute (Thailand) is routinely operated for X-ray absorption spectroscopy (XAS) in an intermediate photon energy range (1.25-10 keV). The photon energy is scanned by using a double-crystal monochromator, the crystal pair of which can be interchanged among KTP(011), InSb(111), Si(111) and Ge(220). The experimental set-up conveniently facilitates XAS measurements in transmission and fluorescence-yield modes at several K-edges of elements ranging from magnesium to zinc. Instrumentation and specification of the beamline and the XAS station are described, together with the determination of the available photon flux [0.1-6 × 10(10) photon s(-1) (100 mA)(-1)], energy resolution (1-5 × 10(-4)) and stability of photon energy calibration (0.07 eV), representing the beamline performance. Data quality and accuracy of XANES and EXAFS measured at BL8 are compared with those of other well established beamlines. A noted distinction of BL8 is its relatively high sensitivity for studying phosphorous, sulfur and chlorine in diluted systems and its maximum beam size of 14 mm (width) × 1 mm (height), which is suitable for bulk characterization. PMID:23093751

Klysubun, Wantana; Sombunchoo, Panidtha; Deenan, Weeraya; Kongmark, Chanapa

2012-11-01

280

Aluminum impurities in silicon: Investigation of x-ray Raman scattering in total reflection x-ray fluorescence spectroscopy  

NASA Astrophysics Data System (ADS)

Total reflection x-ray fluorescence using synchrotron radiation from the Stanford Synchrotron Radiation Laboratory has been used to study Al impurities on Si wafer surfaces. For primary excitation energies below the Si K absorption edge an inelastic resonance scattering due to resonant x-ray Raman scattering is observed. This scattering dominates the background behavior of the Al K fluorescence line, and consequently limits the achievable sensitivity for detection of Al surface contaminants. The energy and angle dependence of the resonant x-ray Raman scattering has been investigated to determine the experimental conditions for which the highest sensitivity for Al can be achieved. We find that for a precise determination of the achievable sensitivity, the specific shape of the continuous Raman background has to be taken into account. Our calculations demonstrate a minimum detection limit for Al of 6×109 atoms/cm2 for a 10 000 s count time.

Baur, K.; Kerner, J.; Brennan, S.; Singh, A.; Pianetta, P.

2000-10-01

281

Surface relaxation in liquid water and methanol studied by x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy is a powerful probe of local electronic structure in disordered media. By employing extended x-ray absorption fine structure spectroscopy of liquid microjets, the intermolecular O-O distance has been observed to undergo a 5.9% expansion at the liquid water interface, in contrast to liquid methanol for which there is a 4.6% surface contraction. Despite the similar properties of liquid water and methanol (e.g., abnormal heats of vaporization, boiling points, dipole moments, etc.), this result implies dramatic differences in the surface hydrogen bond structure, which is evidenced by the difference in surface tension of these liquids. This result is consistent with surface vibrational spectroscopy, which indicates both stronger hydrogen bonding and polar ordering at the methanol surface as a consequence of "hydrophobic packing" of the methyl group.

Wilson, Kevin R.; Schaller, R. D.; Co, D. T.; Saykally, R. J.; Rude, Bruce S.; Catalano, T.; Bozek, J. D.

2002-10-01

282

EUV, X-ray, and gamma-ray instrumentation for astronomy and atomic physics; Proceedings of the Meeting, San Diego, CA, Aug. 7-11, 1989  

Microsoft Academic Search

Topics discussed in this volume include hard X-ray and gamma-ray imaging techniques, hard X-ray and gamma-ray spectroscopic and imaging detectors, X-ray\\/EUV solid-state imagers, balloon and spaceborne experiments and missions, laboratory atomic physics instrumentation, and proportional counter detectors. Other topics discussed are high-resolution X-ray spectrometers, detector calibration, position readout techniques, and X-ray\\/EUV optics for astronomy and microscopy. Papers are presented on

Charles J. Hailey; Oswald H. W. Siegmund

1989-01-01

283

Environment of hafnium and silicon in Hf-based dielectric films: An atomistic study by x-ray absorption spectroscopy and x-ray diffraction  

Microsoft Academic Search

The atomic structure of HfSiO and HfSiON was investigated before and after thermal annealing using x-ray diffraction and x-ray absorption spectroscopy. In HfSiO, the Hf atoms are arranged in a monoclinic HfO2 structure with Hf as second nearest neighbors, while Si is in a SiO2 environment. Thermal annealing induces crystallization of HfSiO with subtle changes in Hf-Hf distances. In the

J. Morais; L. Miotti; K. P. Bastos; S. R. Teixeira; I. J. R. Baumvol; A. L. P. Rotondaro; J. J. Chambers; M. R. Visokay; L. Colombo; M. C. Martins Alves

2005-01-01

284

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

NASA Astrophysics Data System (ADS)

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 comparables 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) Å, which was comparable to the distances observed for aromatic-bound iodine in references (1.99(1)-2.07(6) Å), and significantly shorter than that observed for aliphatic-bound iodine (2.15(2)-2.16(2) Å). These results are in agreement with previous conclusions from X-ray photoelectron spectroscopy and from electrospray ionization mass spectrometry. These results collectively suggest that the aromatic-bound iodine is stable in the various aquifers of this study.

Schlegel, Michel L.; Reiller, Pascal; Mercier-Bion, Florence; Barré, Nicole; Moulin, Valérie

2006-11-01

285

Characterization and Evolution of the Swift X-ray Telescope Instrumental Background  

NASA Technical Reports Server (NTRS)

The X-ray telescope (XRT) on board the Swift Gamma Ray Burst Explorer has successfully operated since the spacecraft launch on 20 November 2004, automatically locating GRB afterglows, measuring their spectra and lightcurves and performing observations of high-energy sources. In this work we investigate the properties of the instrumental background, focusing on its dynamic behavior on both long and short timescales. The operational temperature of the CCD is the main factor that influences the XRT background level. After the failure of the Swift active on-board temperature control system, the XRT detector now operates at a temperature range between -75C and -45C thanks to a passive cooling Heat Rejection System. We report on the long-term effects on the background caused by radiation, consisting mainly of proton irradiation in Swift's low Earth orbit and on the short-term effects of transits through the South Atlantic Anomaly (SAA), which expose the detector to periods of intense proton flux. We have determined the fraction of the detector background that is due to the internal, instrumental background and the part that is due to unresolved astrophysical sources (the cosmic X-ray background) by investigating the degree of vignetting of the measured background and comparing it to the expected value from calibration data.

Hill, Joanne; Pagani, C.; Morris, D. C.; Racusin, J.; Grupe, D.; Vetere, L.; Stroh, M.; Falcone, A.; Kennea, J.; Burrows, D. N.; Nousek, J. A.; Abbey, A. F.; Angelini, L.; Beardmore, A. P.; Campana, S.; Capalbi, M.; Chincarini, G.; Citterio O.; Cusumano, G.; Giommi, P.; Godet, O.; Hill, J. E.; LaParola, V.; Mangano, V.; Mineo, T.

2007-01-01

286

Caliste-SO X-ray micro-camera for the STIX instrument on-board Solar Orbiter space mission  

NASA Astrophysics Data System (ADS)

The Spectrometer Telescope for Imaging X-rays (STIX) is an instrument on the Solar-Orbiter space mission that performs hard X-ray imaging spectroscopy of solar flares. It consists of 32 collimators with grids and 32 spectrometer units called Caliste-SO for indirect Fourier-transform imaging. Each Caliste-SO device integrates a 1 cm2 CdTe pixel sensor with a low-noise low-power analog front-end ASIC and circuits for supply regulation and filtering. The ASIC named IDeF-X HD is designed by CEA/Irfu (France) whereas CdTe-based semiconductor detectors are provided by the Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute (Switzerland). The design of the hybrid, based on 3D Plus technology (France), is well suited for STIX spectroscopic requirements (1 keV FWHM at 6 keV, 4 keV low-level threshold) and system constraints (4 W power and 5 kg mass). The performance of the sub-assemblies and the design of the first Caliste-SO prototype are presented.

Meuris, A.; Hurford, G.; Bednarzik, M.; Limousin, O.; Gevin, O.; Le Mer, I.; Martignac, J.; Horeau, B.; Grimm, O.; Resanovic, R.; Krucker, S.; Orlea?ski, P.

2012-12-01

287

Quick extended x-ray absorption fine structure instrument with millisecond time scale, optimized for in situ applications  

SciTech Connect

In order to learn about in situ structural changes in materials at subseconds time scale, we have further refined the techniques of quick extended x-ray absorption fine structure (QEXAFS) and quick x-ray absorption near edge structure (XANES) spectroscopies at beamline X18B at the National Synchrotron Light Source. The channel cut Si (111) monochromator oscillation is driven through a tangential arm at 5 Hz, using a cam, dc motor, pulley, and belt system. The rubber belt between the motor and the cam damps the mechanical noise. EXAFS scan taken in 100 ms is comparable to standard data. The angle and the angular range of the monochromator can be changed to collect a full EXAFS or XANES spectrum in the energy range 4.7-40.0 KeV. The data are recorded in ascending and descending order of energy, on the fly, without any loss of beam time. The QEXAFS mechanical system is outside the vacuum system, and therefore changing the mode of operation from conventional to QEXAFS takes only a few minutes. This instrument allows the acquisition of time resolved data in a variety of systems relevant to electrochemical, photochemical, catalytic, materials, and environmental sciences.

Khalid, S.; Caliebe, W.; Siddons, P.; So, I.; Clay, b.; Hanson, J.; Wang, Q.; Frenkel, A.; Marinkovicl, N.; Hould, N.; ginder-Vogel, M.; Landrot, G.L.; Sparks, D.L.; Ganjoo, A.

2010-01-19

288

High resolution x-ray fluorescence spectroscopy - a new technique for site- and spin-selectivity  

SciTech Connect

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 K{alpha} and K{beta} 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.

Wang, Xin [Univ. of California, Davis, CA (United States). Dept. of Applied Science]|[Lawrence Berkeley National Lab., CA (United States)

1996-12-01

289

Pixellated Cd(Zn)Te high-energy X-ray instrument  

PubMed Central

We have developed a pixellated high energy X-ray detector instrument to be used in a variety of imaging applications. The instrument consists of either a Cadmium Zinc Telluride or Cadmium Telluride (Cd(Zn)Te) detector bump-bonded to a large area ASIC and packaged with a high performance data acquisition system. The 80 by 80 pixels each of 250 ?m by 250 ?m give better than 1 keV FWHM energy resolution at 59.5 keV and 1.5 keV FWHM at 141 keV, at the same time providing a high speed imaging performance. This system uses a relatively simple wire-bonded interconnection scheme but this is being upgraded to allow multiple modules to be used with very small dead space. The readout system and the novel interconnect technology is described and how the system is performing in several target applications.

Seller, P.; Bell, S.; Cernik, R.J.; Christodoulou, C.; Egan, C.K.; Gaskin, J.A.; Jacques, S.; Pani, S.; Ramsey, B.D.; Reid, C.; Sellin, P.J.; Scuffham, J.W.; Speller, R.D.; Wilson, M.D.; Veale, M.C.

2012-01-01

290

Algorithms for a hand-held miniature x-ray fluorescence analytical instrument  

SciTech Connect

The purpose of this joint program was to provide technical assistance with the development of a Miniature X-ray Fluorescence (XRF) Analytical Instrument. This new XRF instrument is designed to overcome the weaknesses of spectrometers commercially available at the present time. Currently available XRF spectrometers (for a complete list see reference 1) convert spectral information to sample composition using the influence coefficients technique or the fundamental parameters method. They require either a standard sample with composition relatively close to the unknown or a detailed knowledge of the sample matrix. They also require a highly-trained operator and the results often depend on the capabilities of the operator. In addition, almost all existing field-portable, hand-held instruments use radioactive sources for excitation. Regulatory limits on such sources restrict them such that they can only provide relatively weak excitation. This limits all current hand-held XRF instruments to poor detection limits and/or long data collection times, in addition to the licensing requirements and disposal problems for radioactive sources. The new XRF instrument was developed jointly by Quantrad Sensor, Inc., the Naval Research Laboratory (NRL), and the Department of Energy (DOE). This report describes the analysis algorithms developed by NRL for the new instrument and the software which embodies them.

Elam, W.T.; Newman, D.; Ziemba, F. [and others

1998-12-31

291

X-ray and photoelectron spectroscopy of the structure, reactivity, and electronic structure of semiconductor nanocrystals  

SciTech Connect

Semiconductor nanocrystals are a system which has been the focus of interest due to their size dependent properties and their possible use in technological applications. Many chemical and physical properties vary systematically with the size of the nanocrystal and thus their study enables the investigation of scaling laws. Due to the increasing surface to volume ratio as size is decreased, the surfaces of nanocrystals are expected to have a large influence on their electronic, thermodynamic, and chemical behavior. In spite of their importance, nanocrystal surfaces are still relatively uncharacterized in terms of their structure, electronic properties, bonding, and reactivity. Investigation of nanocrystal surfaces is currently limited by what techniques to use, and which methods are suitable for nanocrystals is still being determined. This work presents experiments using x-ray and electronic spectroscopies to explore the structure, reactivity, and electronic properties of semiconductor (CdSe, InAs) nanocrystals and how they vary with size. Specifically, x-ray absorption near edge spectroscopy (XANES) in conjunction with multiple scattering simulations affords information about the structural disorder present at the surface of the nanocrystal. X-ray photoelectron spectroscopy (XPS) and ultra-violet photoelectron spectroscopy (UPS) probe the electronic structure in terms of hole screening, and also give information about band lineups when the nanocrystal is placed in electric contact with a substrate. XPS of the core levels of the nanocrystal as a function of photo-oxidation time yields kinetic data on the oxidation reaction occurring at the surface of the nanocrystal.

Hamad, K.S.

2000-05-01

292

X-ray photo-emission and energy dispersive spectroscopy of HA coated titanium  

SciTech Connect

The purpose of this study was to determine the chemical composition changes of hydroxyapatite (HA) coated titanium using surface analysis (x-ray photo-emission) and bulk analysis (energy dispersive spectroscopy). The specimens examined were controls, 30 minutes and 3 hours aged specimens in distilled water or 0.2M sodium phosphate buffer (pH 7.2) at room temperature. Each x-ray photo-emission cycle consisted of 3 scans followed by argon sputtering for 10 minutes for a total of usually 20 cycles, corresponding to a sampling depth of {approximately} 1500 {angstrom}. The energy dispersive spectroscopy analysis was on a 110 by 90 {mu}m area for 500 sec. Scanning electron microscopy examination showed crystal formation (3P{sub 2}O{sub 5}*2CAO*?H{sub 2}O by energy dispersive spectroscopy analysis) on the HA coating for the specimens aged in sodium phosphate buffer. The x-ray photo-emission results indicated the oxidation effect of water on the titanium (as TiO{sub 2}) and the effect of the buffer to increase the surface concentration of phosphorous. No differences in the chemical composition were observed by energy dispersive spectroscopy analysis. The crystal growth was only observed for the sodium phosphate buffer specimens and only on the HA surface.

Drummond, J.L.; Steinberg, A.D. [Univ. of Illinois, Chicago, IL (United States); Krauss, A.R. [Argonne National Lab., IL (United States)] [and others

1997-08-01

293

Structure of the Mn complex in photosystem II: Insights from x-ray spectroscopy  

SciTech Connect

We have used Mn K-edge absorption and Kb emission spectroscopies to determine the oxidation states of the Mn complex in the various S-states. We have started exploring the new technique of resonant inelastic X-ray scattering spectroscopy (RIXS); this technique can be characterized as a Raman process that uses K-edge energies (1s to 4p, {approx}6550 eV) to obtain L-edge-like spectra (2p to 3d, {approx}650 eV). The relevance of these data to the oxidation states and structure of the Mn complex is presented. We have obtained EXAFS data from the S0 and S3 states and observed heterogeneity in the Mn-Mn distances, leading us to conclude that there may be three rather than two di-(mu)-oxo bridged units present per tetranuclear Mn cluster. In addition, we have obtained data using Ca/Sr X-ray spectroscopy that provide evidence for a heteronuclear Mn/Ca cluster. The possibility of three di-(mu)-oxo-bridged Mn Mn moieties and the proximity of Ca is incorporated into developing structural models for the Mn cluster. The involvement of bridging and terminal O ligands of Mn in the mechanism of oxygen evolution is discussed in the context of our X-ray spectroscopy results.

Yachandra, Vittal K.

2002-04-02

294

Multilayer graphene stacks grown by different methods-thickness measurements by X-ray diffraction, Raman spectroscopy and optical transmission  

NASA Astrophysics Data System (ADS)

X-ray diffraction, Raman spectroscopy and Optical absorption estimates of the thickness of graphene multi layer stacks (number of graphene layers) are presented for three different growth techniques. The objective of this work was focused on comparison and reconciliation of the two already widely used methods for thickness estimates (Raman and Absorption) with the calibration of the X-ray method as far as Scherer constant K is concerned and X-ray based Wagner-Aqua extrapolation method.

Tokarczyk, M.; Kowalski, G.; K?pa, H.; Grodecki, K.; Drabi?ska, A.; Strupi?ski, W.

2013-12-01

295

Local structure of LiCoO2 nanoparticles studied by Co Kedge x-ray absorption spectroscopy  

Microsoft Academic Search

We have studied the local structure of LiCoO2 nanoparticles by Co K-edge x-ray absorption spectroscopy as a function of particle size. Extended x-ray absorption fine structure data reveal substantial changes in the near neighbor distances and the associated mean square relative displacements with decreasing particle size. X-ray absorption near edge structure spectra show clear local geometrical changes with decreasing particle

L Maugeri; A Iadecola; B Joseph; L Simonelli; L Olivi; M Okubo; I Honma; H Wadati; T Mizokawa; N L Saini

2012-01-01

296

The X-ray microcalorimeter spectrometer (XMS): a reference cryogenic instrument for Constellation-X  

NASA Astrophysics Data System (ADS)

The first two of four observatories in the constellation will be launched together in 2013 and followed a year later by the launch of the remaining pair. The four will independently orbit the Sun-Earth Lagrange point L2. An instrument compliment resides in the focal plane module (FPM) of each observatory 10 m from the optics module and consists of three hard X-ray telescope (HXT) detectors, a reflection grating spectrometer (RGS) focal plane CCD camera (RFC) and an X-ray microcalorimeter spectrometer (XMS). Instrument awards are scheduled for early 2006. The reference detector system for XMS is a 32 × 32 array of microcalorimetric superconducting transition edge sensors (TES) with SQUID based multiplexed readout and amplification. A multi-stage continuous ADR will provide the stable 50 mK desired for the TES array and a stable 1 K for the SQUID amplifiers while also lifting thermal parasitic and inefficiency loads to a 6 K cryocooler interface. The 6 K cryocooler is expected to emerge from the joint-project advanced cryocooler technology development program (ACTDP) in which Constellation-X is an active partner. Project pre-formulation activities are marked by extensive technology development necessitating early, but realistic, thermal and cooling load requirements for ADR and ACTDP-cryocooler design points. Such requirements are driven by the encompassing XMS cryostat and ultimately by the thermal environment imposed by the FPM. It is further desired that the XMS instrument be able to operate horizontally in the laboratory, with a warm vacuum shell, during an extensive calibration regime. It is that highly integrated reference instrument (microcalorimeter, ADR, cryocooler and cryostat) that will be examined here.

Whitehouse, Paul L.; Shirron, Peter J.; Kelley, Richard L.

2004-06-01

297

The X-ray Microcalorimeter Spectrometer (XMS): A Reference Cryogenic Instrument Design for Constellation-X  

NASA Technical Reports Server (NTRS)

Constellation-X, a mission now belonging to the Beyond Einstein initiative, is being planned to inherit the x-ray sky from Chandra, XMM-Newton and Astro-E. The first two of four observatories in the constellation will be launched together in 2013 and followed a year later by the launch of the remaining two. The four will independently orbit the Sun-Earth Lagrange point L2. An instrument compliment resides in the Focal Plane Module (FPM) of each observatory 10 m from the Optics Module and consists of three Hard X-ray Telescope (HXT) detectors, a Reflection Grating Spectrometer (RGS) focal plane CCD camera and an X-ray Microcalorimeter Spectrometer (XMS). Instrument awards are scheduled for early 2006. The reference detector for XMS is a 32 x 32 array of microcalorimetric superconducting Transition Edge Sensors (TES). Each pixel casts a variable resistance in a SQUID based multiplexed readout circuit which is coupled to series SQUID arrays for amplification and finally read out by external electronics. A multi-stage continuous ADR will provide the stable 50 mK desired for the TES array and a stable 1 K for the series SQUID arrays while also lifting thermal parasitic and inefficiency loads to a 6 K cryocooler interface. The 6 K cryocooler is expected to emerge from the joint-project Advanced Cryocooler Technology Development Program (ACTDP) in which Constellation-X is an active participant. Project Pre-Formulation activities are marked by extensive technology development necessitating early, but realistic, thermal and cooling load requirements for ADR and ACTDP-cryocooler design points. Such requirements are driven by the encompassing XMS cryostat and ultimately by the thermal environment imposed by the FPM. It is further desired that the XMS instrument be able to operate on its side in the laboratory, with a warm vacuum shell, during an extensive calibration regime. It is that reference system design of the XMS instrument (microcalorimeter, ADR, cryocooler and cryostat) which is the subject of this paper.

Whitehouse, Paul L.

2003-01-01

298

X-ray spectroscopy of the photosynthetic oxygen-evolving complex  

SciTech Connect

Water oxidation to dioxygen in photosynthesis is catalyzed by a Mn4Ca cluster with O bridging in Photosystem II (PS II) of plants, algae and cyanobacteria. A variety of spectroscopic methods have been applied to analyzing the participation of the complex. X-ray spectroscopy is particularly useful because it is element-specific, and because it can reveal important structural features of the complex with high accuracy and identify the participation of Mn in the redox chemistry. Following a brief history of the application of X-ray spectroscopy to PS II, an overview of newer results will be presented and a description of the present state of our knowledge based on this approach.

Sauer, Ken; Yano, Junko; Yachandra, Vittal K

2007-04-05

299

Technology Development for the Constellation-X Spectroscopy X-Ray Telescope  

NASA Technical Reports Server (NTRS)

The Constellation-X Spectroscopy X-ray Telescope (SXT) is a large diameter, high throughput, grazing incidence imaging mirror system, designed to perform high sensitivity spectroscopy of cosmic X-ray sources in the 0.2-10.0 keV band. The baseline effective area requirement is -3 m# at 1 keV. The system-level angular-resolution requirement is a 15-arcseconds half-power diameter, with a 5-arcsecond goal. The effective area is attained through a modular design, involving the nesting of many confocal, thin-walled Wolter I mirror segments. Considerable progress has been made in developing thin, thermally formed, glass mirror substrates that meet or better the angular-resolution requirement. Several approaches to mounting and aligning reflector segments into a mirror system are under investigation. We report here on the progress of the SXT technology development program toward reaching the performance goals.

Petre, Robert; Lehan, John; O'Dell, Stephen; Owens, Scott; Reid, Paul B.; Saha, Timo; Stewart, Jeff; Jones, William D.; Zhang, William

2005-01-01

300

Quantitative Elemental Mapping at Atomic Resolution Using X-Ray Spectroscopy  

NASA Astrophysics Data System (ADS)

Elemental mapping using energy-dispersive x-ray spectroscopy in scanning transmission electron microscopy, a well-established technique for precision elemental concentration analysis at submicron resolution, was first demonstrated at atomic resolution in 2010. However, to date atomic resolution elemental maps have only been interpreted qualitatively because the elastic and thermal scattering of the electron probe confounds quantitative analysis. Accounting for this scattering, we present absolute scale quantitative comparisons between experiment and quantum mechanical calculations for both energy dispersive x-ray and electron energy-loss spectroscopy using off-axis reference measurements. The relative merits of removing the scattering effects from the experimental data against comparison with direct simulations are explored.

Kothleitner, G.; Neish, M. J.; Lugg, N. R.; Findlay, S. D.; Grogger, W.; Hofer, F.; Allen, L. J.

2014-02-01

301

The hydrogen bond of water from the perspective of soft X-ray spectroscopy.  

PubMed

Its importance for life and its unusual properties keep water within the focus of ongoing research; this focus especially applies to water in the liquid phase. Scientists agree that the hydrogen-bond network, which is formed by interactions between the water molecules, is key for understanding the anomalies of water. However, a better understanding of the structure of this network, as well as its dynamics, must yet be established. Soft X-ray spectroscopy allows the investigation of the local electronic structure of water by probing the occupied and unoccupied valence molecular orbitals. In this Focus Review, we present soft-X-ray-based techniques, their development in terms of liquid spectroscopy, and recent studies on the hydrogen-bond network of liquid water. PMID:22945810

Lange, Kathrin M; Aziz, Emad F

2013-02-01

302

Toward Femtosecond X-ray Spectroscopy at the Advanced Light Source  

SciTech Connect

The realization of tunable, ultrashort pulse x-ray sources promises to open new venues of science and to shed new light on long-standing problems in condensed matter physics and chemistry. Fundamentally new information can now be accessed. Used in a pump-probe spectroscopy, ultrashort x-ray pulses provide a means to monitor atomic rearrangement and changes in electronic structure in condensed-matter and chemical systems on the physically-limiting time-scales of atomic motion. This opens the way for the study of fast structural dynamics and the role they play in phase transitions, chemical reactions and the emergence of exotic properties in materials with strongly interacting degrees of freedom. The ultrashort pulse x-ray source developed at the Advanced Light Source at the Lawrence Berkeley Laboratory is based on electron slicing in storage rings, and generates {approx}100 femtosecond pulses of synchrotron radiation spanning wavelengths from the far-infrared to the hard x-ray region of the electromagnetic spectrum. The tunability of the source allows for the adaptation of a broad range of static x-ray spectroscopies to useful pump-probe measurements. Initial experiments are attempted on transition metal complexes that exhibit relatively large structural changes upon photo-excitation and which have excited-state evolution determined by strongly interacting structural, electronic and magnetic degrees of freedom. Specifically, iron(II) complexes undergo a spin-crossover transition upon optical irradiation. The dynamics of the transition involve a metal-to-ligand charge transfer, a {Delta}S=2 change in magnetic moment and 10% bond dilation in the first coordination shell of the iron. Studies of the electronic dynamics are studied with time-resolved optical absorption measurements. The current progress of time-resolved structural studies to complete the picture of the spin-crossover transition is presented.

Chong, Henry Herng Wei

2004-04-16

303

EUV, X-ray, and gamma-ray instrumentation for astronomy III; Proceedings of the Meeting, San Diego, CA, July 22-24, 1992  

NASA Astrophysics Data System (ADS)

The present conference discusses the optimization of Nb tunnel junctions as X-ray detectors, superconducting tunnel junctions for X-ray spectroscopy, diffuse X-ray spectrometer experiment, a microstrip proportional counter, the X-ray performance of an imaging gas-scintillation proportional counter, and X-ray imaging with the XSPECT/SODART microstrip proportional counters. Also discussed are radiation-entrance windows for CCD detectors, detection of X-rays with an optical imaging chamber, ultrahigh-resolution photon-counting system, an X-ray detector using superconducting Al tunnel junctions, the performance and limitations of thermal detectors for X-ray astronomy, imaging solar flares in hard X-rays using Fourier telescopes, and a modular rotating collimator imaging X-ray spectrometer. (For individual items see A93-29477 to A93-29527)

Siegmund, Oswald H. W.

1992-10-01

304

Time resolved spectroscopy of ultrashort pulse laser generated x rays using von Hámos crystal spectroscopy  

Microsoft Academic Search

A diagnostic currently being used for ultrashort pulse laser matter interactions at the Lawrence Livemore National Laboratory is presented. Two cylindrical curved crystals are used as collection optics and diffractive elements in the von Hámos geometry. The dispersed x rays are focused onto the slit of an ultrafast x-ray streak camera. The small nature of the streak camera allows the

Ronnie Shepherd; Patrick Audebert; Rex Booth; Bruce Young; Jim Bonlie; Don Nelson; Steve Shiromizu; Dwight Price; Douglas Norman; Jim Dunn; Klaus Widmann; Paul Springer

2004-01-01

305

Hydrazine reduction of transition metal oxides: In situ characterization using x-ray photoelectron spectroscopy  

Microsoft Academic Search

Among the first row transition metal oxides from VâOâ to ZnO, CuO was found to be the most easily reduced by hydrazine. CuO surfaces exposed to hydrazine at approx.10⁻⁶ Torr could be reduced to the metallic state at room temperature. Reduction kinetics, continuously measured at the surface using in situ x-ray photoelectron spectroscopy (XPS) at hydrazine pressures of 6 x

D. M. Littrell; B. J. Tatarchuk

1986-01-01

306

Slow dynamics and aging in colloidal gels studied by x-ray photon correlation spectroscopy  

SciTech Connect

Slow, nonequilibrium dynamics during delayed sedimentation in a colloidal depletion gel was studied by x-ray photon correlation spectroscopy. The intermediate scattering functions change during the process from stretched to compressed exponential decays, indicating a jamming transition toward full aging. A complex aging behavior follows this process; it is proposed that large-scale network deformations trigger an unjamming, leading to the final collapse of the gel.

Fluerasu, Andrei; Moussaied, Abdellatif; Madsen, Anders [European Synchrotron Radiation Facility, Boite Postale 220, F-38043 Grenoble (France); Schofield, Andrew [Department of Physics and Astronomy, University of Edinburgh, Edinburgh (United Kingdom)

2007-07-15

307

XPS: a multi-channel preamplifier-shaper IC for X-ray spectroscopy  

Microsoft Academic Search

An integrated circuit featuring 48 channels of charge sensitive preamplifiers followed by variable-gain pulse shaping amplifiers is being developed as part of an X-ray spectrometer with a highly segmented detector to handle high fluxes in synchrotron experiments. Such detector systems can provide excellent energy resolution combined with one-dimensional spatial information. The IC combines many basic spectroscopy amplifier functions with a

B. Krieger; I. Kipnis; B. A. Ludewigt

1998-01-01

308

X-ray absorption spectroscopy beyond the core-hole lifetime  

SciTech Connect

A new technique to overcome the core-hole lifetime broadening in x-ray absorption spectroscopy is presented. It utilizes a high resolution fluorescence spectrometer which can be used to analyze the fluorescence photon energy with better resolution than the natural lifetime width. Furthermore, the high resolution spectrometer can also be used to select the final state in the fluorescence process which can offer spin selectivity even without long range magnetic order in the sample.

Haemaelaeinen, K.; Hastings, J.B.; Siddons, D.P.; Berman, L.

1992-01-01

309

X-ray absorption spectroscopy beyond the core-hole lifetime  

SciTech Connect

A new technique to overcome the core-hole lifetime broadening in x-ray absorption spectroscopy is presented. It utilizes a high resolution fluorescence spectrometer which can be used to analyze the fluorescence photon energy with better resolution than the natural lifetime width. Furthermore, the high resolution spectrometer can also be used to select the final state in the fluorescence process which can offer spin selectivity even without long range magnetic order in the sample.

Haemaelaeinen, K.; Hastings, J.B.; Siddons, D.P.; Berman, L.

1992-10-01

310

X-ray excited visible luminescence spectroscopy of organic materials using a portable optical spectrometer.  

PubMed

The use of a portable video telescope, mounted externally to a beamline endstation, to obtain synchrotron-radiation-excited visible luminescence, is described. Real-time video monitoring permits simple and quick alignment, and allows a visual record of the luminescence experiment. The telescope is fibre-optic-coupled to an optical spectrometer. Examples are given of X-ray excited optical spectroscopy from organic materials for light-emitting-diode applications. PMID:16120997

Maiorano, Vincenzo; Matino, Francesca; Cingolani, Roberto; Thompson, Julie; Blyth, Robert I R

2005-09-01

311

Uranium-involving electrode processes in chloride melts: An x-ray absorption spectroscopy study  

Microsoft Academic Search

Products of anodic dissolution of uranium metal and the cathodic reduction of uranium(IV) ions in a molten eutectic mixture\\u000a of lithium and potassium chlorides are studied at 450?C using x-ray absorption spectroscopy. It is shown that UCl\\u000a 6\\u000a 3?\\u000a — ions form in the melt as a result of the metal’s anodic dissolution, and the metal-ligand distance in the complex

V. A. Volkovich; I. B. Polovov; C. A. Sharrad; I. May; J. M. Charnock

2007-01-01

312

X-ray photoelectron spectroscopy study of radiofrequency-sputterer refractory-compound steel interfaces  

Microsoft Academic Search

Radiofrequency sputtering was used to deposit MoâC, MoâBâ, and MoSi2 coatings on 440C steel substrates. Both sputter etched and preoxidized substrates were used, and the films were deposited with and without a substrate bias of -300 V. The composition of the coatings was measured as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. In the

D. R. Wheeler; W. A. Brainard

1978-01-01

313

Angle resolved X-ray photoelectron spectroscopy study of Pd\\/NbO x \\/Nb interfaces  

Microsoft Academic Search

The thermal stability of ultrathin palladium overlayers deposited at room temperature onto oxidized niobium has been studied by high resolution angle-resolved X-ray photoelectron spectroscopy. The Pd overlayers were almost not influenced by heating up to temperatures ?550 K. Heating above this temperature leads to reduction of Nb2O5 oxide accompanied by dissolution of oxygen into the bulk Nb. Inward diffusion of

Michel Malick Thiam; Zden?k Bastl

2002-01-01

314

Characterization of coprecipitated nickel on silica methanation catalysts by x-ray photoelectron spectroscopy  

Microsoft Academic Search

An x-ray photoemission spectroscopy study of a series of standard nickel compounds (Ni, NiO, Ni(OH)â, NiSiOâ) and silica-supported nickel methanation catalysts has been conducted. The binding energies and spectral shapes of the standard samples provide a data base which has been used to understand the catalyst spectra. The activity and thermal stability of coprecipitated nickel catalysts has been attributed to

R. B. Shalvoy; P. J. Reucroft; B. H. Davis

1979-01-01

315

Observation of phase transition of cesium manganese hexacyanoferrates by X-ray absorption spectroscopy  

Microsoft Academic Search

Cesium manganese hexacyanoferrates exhibit an interesting phenomenon of temperature-induced phase transition accompanied by a variation in the magnetic susceptibility. We observed the variation in the electronic state of Mn during the phase transition by using X-ray absorption spectroscopy. The results of the analyses showed that the content ratio of FeII–CN–MnIII and FeIII–CN–MnII systematically varied during the phase transition. However, the

Kotaro Ishiji; Tomoyuki Matsuda; Hiroko Tokoro; Toshiaki Iwazumi; Kazuhito Hashimoto; Shin-Ichi Ohkoshi

2007-01-01

316

Coordination of aluminum atoms in anodic aluminum oxides, based on ultrasoft x-ray emission spectroscopy  

Microsoft Academic Search

Results are given of the investigation of the coordination of aluminum atoms in seven types of porous anodic aluminum oxides by ultrasoft x-ray emission spectroscopy. It is shown that a difference exists between the anodic aluminum oxides obtained in different electrolytes. The change in the relative intensity of the maxima of the Al L\\/sub 2,3\\/ emission band was used to

M. A. Chernykh; V. T. Belov; V. A. Terekhov; N. A. Amirova

1988-01-01

317

X-ray absorption spectroscopy of cadmium phytochelatin and model systems  

Microsoft Academic Search

Higher plants, algae and some yeasts respond to potentially toxic heavy metals such as cadmium by synthesizing phytochelatins and related cysteine-rich polypeptides. We have used X-ray absorption spectroscopy to study the nature of cadmium binding in such peptides isolated from maize (Zea mays) exposed to low levels of cadmium, and in two synthetic cadmium–peptide complexes, Cd–(?-Glu-Cys)3Gly and Cd–(?-Glu-Cys)3Gly. We have

Ingrid J. Pickering; Roger C. Prince; Graham N. George; Wilfried E. Rauser; W. A. Wickramasinghe; Andrew A. Watson; Charles T. Dameron; Ian G. Dance; David P. Fairlie; David E. Salt

1999-01-01

318

Comprehensive x-ray photoelectron spectroscopy study on compositional gradient lanthanum silicate film  

Microsoft Academic Search

Oxygen bonding in La-silicate film with compositional gradient has been characterized by x-ray photoelectron spectroscopy. Based on an analytical model of bridging and nonbridging oxygen, the O 1s spectra arising from La-silicate layer have been deconvoluted with compositionally dependent parameters. For a composition ratio of 1:1 for SiO2 and LaO1.5 on the surface of the La-silicate layer, negative binding energy

K. Kakushima; K. Tachi; J. Song; S. Sato; H. Nohira; E. Ikenaga; P. Ahmet; K. Tsutsui; N. Sugii; T. Hattori; H. Iwai

2009-01-01

319

Analysis of some Nigerian solid mineral ores by energy-dispersive X-ray fluorescence spectroscopy  

Microsoft Academic Search

Determination of major, minor and trace elements in some Nigerian solid mineral ores by energy-dispersive X-ray fluorescence (EDXRF) spectroscopy is described. Concentration values of major, minor and trace elements for Z>18 are reported. The mineral ores studied include (i) tantalite–coloumbite minerals, (ii) bismuth minerals and (iii) lead minerals. The accuracy and precision of the technique for chemical analysis was assured

E. I. Obiajunwa

2001-01-01

320

K- and L-shell x-ray spectroscopy of indirectly driven implosions  

Microsoft Academic Search

Time resolved x-ray spectroscopy is used to study the implosion of indirectly driven inertial confinement fusion capsules on the Nova laser. Through the use of high-Z dopants (Ar and Xe) in the fuel, measurements of the peak temperature, from emission line ratios, and density, from line broadening, are obtained. These measurements indicate peak electron temperatures of â¼1--1.6 key and electron

Hammel

1992-01-01

321

K- and L-shell x-ray spectroscopy of indirectly driven implosions  

Microsoft Academic Search

Time resolved x-ray spectroscopy is used to study the implosion of indirectly driven inertial confinement fusion capsules on the Nova laser. Through the use of high-Z dopants (Ar and Xe) in the fuel, measurements of the peak temperature, from emission line ratios, and density, from line broadening, are obtained. These measurements indicate peak electron temperatures of [approximately]1--1.6 key and electron

Hammel

1992-01-01

322

K- and L-shell x-ray spectroscopy of indirectly driven implosions (invited)  

Microsoft Academic Search

Time-resolved x-ray spectroscopy is used to study the implosion of indirectly driven inertial confinement fusion capsules on the Nova laser. Through the use of high-Z dopants (Ar and Xe) in the fuel, measurements of the peak temperature, from emission line ratios, and density, from line broadening, are obtained. These measurements indicate peak electron temperatures of ?1–1.6 keV and electron (and

B. A. Hammel; C. J. Keane; D. R. Kania; J. D. Kilkenny; R. W. Lee; R. Pasha; R. E. Turner; N. D. Delamater

1992-01-01

323

Surface characterization of acid-leached olivines by X-ray photoelectron spectroscopy  

Microsoft Academic Search

X-ray photoelectron spectroscopy was used to study the surface alteration of olivines (fayalite and forsterite) during acid dissolution (0.05 mol 1?1 H2SO4 at room temperature for one day). The abundances of Fe and Mg, relative to Si, in the near surface of olivines decreased after acid dissolution. The divalent cations in the fayalite were removed more readily than those in

Haruhiko Seyama; Mitsuyuki Soma; Atsushi Tanaka

1996-01-01

324

Characterization of sputter-deposited YBaCuO films by X-ray photoelectron spectroscopy  

Microsoft Academic Search

Thin films of YBaCuO have been deposited onto SrTiO3 (100) single crystals by different sputter techniques. At substrate temperatures around 700°C critical current densities as high as 5.9×106 A\\/cm2 at 77 K could be achieved. X-ray photoelectron spectroscopy (XPS) has been used to characterize the surface composition and the surface homogeneity of the films. The existence of the superconducting perovskite

H. Behner; G. Gieres; B. Sipos

1991-01-01

325

Multipixel characterization of imaging CZT detectors for hard x-ray imaging and spectroscopy  

Microsoft Academic Search

We report our in-depth study of Cd-Zn-Te (CZT) crystals to determine an optimum pixel and guard band configuration for Hard X-ray imaging and spectroscopy. We tested 20x20x5mm crystals with 8x8 pixels on a 2.46mm pitch. We have studied different types of cathode \\/ anode contacts and different pixel pad sizes. We present the measurements of leakage current as well as

Santosh V. Vadawale; Jae Sub Hong; Jonathan E. Grindlay; Peter Williams; Minhua Zhang; Eric C. Bellm; Tomohiko Narita; William W. Craig; Bradford H. Parker; Carl M. Stahle; Feng Yan

2004-01-01

326

X-ray photoemission spectroscopy studies of conducting polymer-substrate interfaces: Interfacial electrochemical diffusion  

Microsoft Academic Search

Interfaces between conducting polymer polypyrrole (PP) and transparent conductive materials such as indium tin oxide (ITO) and SnO2 were investigated by x-ray photoemission spectroscopy (XPS). XPS lines of In 3d5\\/2,3\\/2 and Sn 3d5\\/2,3\\/2 were observed in the XPS spectra of electrochemically reduced PP film sides of PP\\/ITO and PP\\/SnO2, respectively. The results indicate that electrochemical diffusion of substrate materials into

Hitoshi Kato; Susumu Takemura; Yasushi Nakajima

1997-01-01

327

Heavy metal-adsorption on micas and clay minerals studied by X-ray photoelectron spectroscopy  

Microsoft Academic Search

X-ray photoelectron spectroscopy (XPS) was used to study the adsorption of Cs-, Ba-, Cu-, Zn-, and Pb-ions on the external surfaces of various, well characterized 2:1 layer silicates (micas and illites).Before studying metal adsorption, it was necessary to determine the charge magnitude of the adsorption surface. This was done for chemically well-characterized micas (margarite, muscovite, sericite). The XPS analyses showed

Susanne Gier; William D. Johns

2000-01-01

328

Early Stage of Silicon Oxidation Studied by in situ X-Ray Photoelectron Spectroscopy  

Microsoft Academic Search

In this study, a clean silicon surface is oxidized in a UHV chamber and the surface suboxide compositions are analyzed using in situ X-ray photoelectron spectroscopy. It is found that the predominant suboxides are Si2O3 and SiO irrespective of crystallographic orientations in the early stages of oxidation. This is interpreted in terms of a significant number of atomic steps existing

Masaru Takakura; Tsuyoshi Ogura; Tsukasa Hayashi; Masataka Hirose

1988-01-01

329

Characterization of laboratory weathered labradorite surfaces using X-ray photoelectron spectroscopy and transmission electron microscopy  

Microsoft Academic Search

Altered surfaces of labradorite resulting from laboratory weathering at pH 4 and 25°C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed nonuniform surface alteration of labradorite weathered at pH 3.7 for 415 days. TEM micrographs showed exsolution lamellae of a more calcic-rich and more sodic-rich phase, each averaging approximately

William P. Inskeep; Edward A. Nater; Paul R. Bloom; Dirk S. Vandervoort; M. Susan Erich

1991-01-01

330

Characterization of laboratory weathered labradorite surfaces using X-ray photoelectron spectroscopy and transmission electron microscopy  

Microsoft Academic Search

Altered surfaces of labradorite resulting from laboratory weathering at pH 4 and 25C were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray photoelectron spectroscopy (XPS). SEM micrographs showed nonuniform surface alteration of labradorite weathered at pH 3.7 for 415 days. TEM micrographs showed exsolution lamellae of a more calcic-rich and more sodic-rich phase, each averaging approximately

W. P. Inskeep; D. S. Vandervoort; E. A. Nater; P. R. Bloom; M. S. Erich

1991-01-01

331

X-Ray Photoelectron Spectroscopy and Electronic Structures of Scheelite and Wolframite-Type Tungstate Crystals  

Microsoft Academic Search

X-ray photoelectron spectroscopy (XPS) of metal tungstates, MWO4, has been carried out to investigate the electronic structures of scheelites (M=Pb, Ca, and Ba) and wolframites (M=Cd and Zn). Relativistic molecular orbital calculations of these tungstates have also been performed. The theoretical results are discussed in comparison with the previous band calculations, and are shown to be in satisfactory agreement with

Minoru Itoh; Naoyuki Fujita; Yoshiyuki Inabe

2006-01-01

332

X-ray spectroscopy characterization of Ar17+ produced by an ECRIS in the afterglow mode  

Microsoft Academic Search

An electron-cyclotron-resonance ion source (ECRIS) operating in the afterglow mode allows to produce pulsed highly charged ion beams. We present a characterization of the first production of pulsed Ar17+ ions from an ECRIS using X-ray spectroscopy techniques. An ion current increase of a factor 3-4 compared to the continuous operating mode with a short rise time (< 100 mu s)

C. Prigent; E. Lamour; J. Mérot; B. Pascal; J.-P. Rozet; M. Trassinelli; D. Vernhet; J.-Y. Pacquet; L. Maunoury; F. Noury; J.-M. Ramillon

2009-01-01

333

Band structure of ZnO from resonant x-ray emission spectroscopy  

Microsoft Academic Search

Soft x-ray emission and absorption spectroscopy of the OK -edge are employed to investigate the electronic structure of wurtzite ZnO(0001). A quasiparticle band structure calculated within the GW approximation agrees well with the data, most notably with the energetic location of the Zn3d-O2p hybridized state and the anisotropy of the absorption spectra. Dispersion in the band structure is mapped using

A. R. H. Preston; B. J. Ruck; L. F. J. Piper; A. Demasi; K. E. Smith; A. Schleife; F. Fuchs; F. Bechstedt; J. Chai; S. M. Durbin

2008-01-01

334

Recent and future developments in low power total reflection X-ray fluorescence spectroscopy  

NASA Astrophysics Data System (ADS)

Today, energy-dispersive X-ray fluorescence (EDXRF) spectroscopy with low power X-ray tubes and thermoelectrically cooled detectors provide analytical performance which in the past was restricted to systems with kW power X-ray tubes and liquid nitrogen cooled Si(Li) detectors. Especially for low power TXRF spectrometers, the sensitivity could be improved by an order of one magnitude in the last 5 years. This progress was mainly based on improvements in quantum efficiency of all components and less on high power excitation sources. Recent developments caused further improvements in the analytical sensitivity as well as in the analytical performance. The introduction of a micro-focus X-ray tube increased the excitation power by a factor of 1.3. An additional improvement could be achieved by optimizing the detector window design. By optimizing the detector entrance geometry, the solid detection angle of a silicon drift detector (SDD) was increased by a factor of 1.8. In addition, the recent development of a new generation of silicon drift detectors increased the active detector area by a factor of three enhancing the peak to background ratio by a factor of two. Furthermore, the high-energy efficiency of this new detector type was significantly improved. As a result of all these improvements the detection limit for nickel could be decreased to a value of 1 pg.

Waldschlaeger, U.

2006-11-01

335

Iron speciation in minerals and glasses probed by -edge X-ray Raman scattering spectroscopy  

NASA Astrophysics Data System (ADS)

We present a spectroscopic study of the iron -edge for several minerals and compounds to reveal information about the oxidation state and the local coordination of iron. We describe a novel approach to probe the iron -edge bulk sensitively using X-ray Raman scattering. Significant changes in the onset and shape of the Fe -edge were observed on ferrous and ferric model compounds with Fe in octahedral and tetrahedral coordination. Simulation of the spectra is possible using an atomic multiplet code, which potentially allows determination of, e.g., crystal-field parameters in a quantitative manner. A protocol is discussed for determination of the Fe oxidation state in compounds by linear combination of spectra of ferric and ferrous end members. The presented results demonstrate the capabilities of Fe -edge spectroscopy by X-ray Raman scattering to extract information on the ratio of trivalent to total iron and local coordination. As X-ray Raman scattering is performed with hard X-rays, this approach is suitable for in situ experiments at high pressure and temperature. It thus may provide indispensable information on oxidation state, electronic structure and local structure of materials that are important for physical and chemical processes of the deep Earth.

Nyrow, A.; Sternemann, C.; Wilke, M.; Gordon, R. A.; Mende, K.; Yava?, H.; Simonelli, L.; Hiraoka, N.; Sahle, Ch. J.; Huotari, S.; Andreozzi, G. B.; Woodland, A. B.; Tolan, M.; Tse, J. S.

2014-05-01

336

An X-ray spectroscopy system and its application to the laser-Compton scattering experiments  

NASA Astrophysics Data System (ADS)

One of the main challenges for the laser-Compton scattering (LCS) experiments with the oblique configuration at the Linac of SINAP is the low signal to noise ( S/N) ratio due to the low intensity of LCS signals. X-ray spectroscopy system mainly consisting of an X-ray Si(Li) detector, electronics, and LabVIEW-based data acquisition has been developed for the low S/N ratio experiments. Spectral characteristics of such a system (i.e., energy and time resolutions, data acquisition efficiency, and system instability) have been determined by the 55Fe, 241Am, and 238Pu radioactive sources. In order to extract the LCS X-ray spectrum, several methods for the enhancement of the S/N ratio have been achieved and data have been taken alternatively with laser pulse on and off. Thanks to these methods the S/ N ratios have been optimized. Finally, the generated LCS X-ray spectrum has been achieved through the subtraction of the on/off laser accumulated spectra.

Luo, W.; Xu, W.; Pan, Q. Y.; Fan, G. T.; Fan, G. W.; Li, Y. J.; Xu, B. J.; Xu, Y.; Yan, Z.; Yang, L. F.

2010-12-01

337

A von Hamos x-ray spectrometer based on a segmented-type diffraction crystal for single-shot x-ray emission spectroscopy and time-resolved resonant inelastic x-ray scattering studies  

NASA Astrophysics Data System (ADS)

We report on the design and performance of a wavelength-dispersive type spectrometer based on the von Hamos geometry. The spectrometer is equipped with a segmented-type crystal for x-ray diffraction and provides an energy resolution in the order of 0.25 eV and 1 eV over an energy range of 8000 eV-9600 eV. The use of a segmented crystal results in a simple and straightforward crystal preparation that allows to preserve the spectrometer resolution and spectrometer efficiency. Application of the spectrometer for time-resolved resonant inelastic x-ray scattering and single-shot x-ray emission spectroscopy is demonstrated.

Szlachetko, J.; Nachtegaal, M.; de Boni, E.; Willimann, M.; Safonova, O.; Sa, J.; Smolentsev, G.; Szlachetko, M.; van Bokhoven, J. A.; Dousse, J.-Cl.; Hoszowska, J.; Kayser, Y.; Jagodzinski, P.; Bergamaschi, A.; Schmitt, B.; David, C.; Lücke, A.

2012-10-01

338

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy  

SciTech Connect

For electronic excitations in the ultraviolet and visible range of the electromagnetic spectrum, the intensities are usually calculated within the dipole approximation, which assumes that the oscillating electric field is constant over the length scale of the transition. For the short wavelengths used in hard X-ray spectroscopy, the dipole approximation may not be adequate. In particular, for metal K-edge X-ray absorption spectroscopy (XAS), it becomes necessary to include higher-order contributions. In quantum-chemical approaches to X-ray spectroscopy, these so-called quadrupole intensities have so far been calculated by including contributions depending on the square of the electric-quadrupole and magnetic-dipole transition moments. However, the resulting quadrupole intensities depend on the choice of the origin of the coordinate system. Here, we show that for obtaining an origin-independent theory, one has to include all contributions that are of the same order in the wave vector consistently. This leads to two additional contributions depending on products of the electric-dipole and electric-octupole and of the electric-dipole and magnetic-quadrupole transition moments, respectively. We have implemented such an origin-independent calculation of quadrupole intensities in XAS within time-dependent density-functional theory, and demonstrate its usefulness for the calculation of metal and ligand K-edge XAS spectra of transition metal complexes.

Bernadotte, Stephan; Atkins, Andrew J.; Jacob, Christoph R. [Karlsruhe Institute of Technology (KIT), Center for Functional Nanostructures and Institute of Physical Chemistry, Wolfgang-Gaede-Str. 1a, 76131 Karlsruhe (Germany)

2012-11-28

339

Origin-independent calculation of quadrupole intensities in X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

For electronic excitations in the ultraviolet and visible range of the electromagnetic spectrum, the intensities are usually calculated within the dipole approximation, which assumes that the oscillating electric field is constant over the length scale of the transition. For the short wavelengths used in hard X-ray spectroscopy, the dipole approximation may not be adequate. In particular, for metal K-edge X-ray absorption spectroscopy (XAS), it becomes necessary to include higher-order contributions. In quantum-chemical approaches to X-ray spectroscopy, these so-called quadrupole intensities have so far been calculated by including contributions depending on the square of the electric-quadrupole and magnetic-dipole transition moments. However, the resulting quadrupole intensities depend on the choice of the origin of the coordinate system. Here, we show that for obtaining an origin-independent theory, one has to include all contributions that are of the same order in the wave vector consistently. This leads to two additional contributions depending on products of the electric-dipole and electric-octupole and of the electric-dipole and magnetic-quadrupole transition moments, respectively. We have implemented such an origin-independent calculation of quadrupole intensities in XAS within time-dependent density-functional theory, and demonstrate its usefulness for the calculation of metal and ligand K-edge XAS spectra of transition metal complexes.

Bernadotte, Stephan; Atkins, Andrew J.; Jacob, Christoph R.

2012-11-01

340

Microelemental and mineral compositions of pathogenic biomineral concrements: SRXFA, X-ray powder diffraction and vibrational spectroscopy data  

NASA Astrophysics Data System (ADS)

X-ray fluorescence analysis using synchrotron radiation (SRXRF), X-ray powder diffraction, infrared and Raman spectroscopy had been applied for determination of microelemental and mineral composition of the kidney stones, gallstones and salivalities from natives of Novosibirsk and Novosibirsk region, Russia. The relationship between mineral, organic and microelemental composition of pathogenic calcilus was shown.

Moroz, T. N.; Palchik, N. A.; Dar'in, A. V.

2009-05-01

341

Calcium in the Oxygen-Evolving Complex: Structural and Mechanistic Role Determined by X-ray Spectroscopy  

PubMed Central

This review describes the results from X-ray absorption spectroscopy studies that have contributed to an understanding of the role of Ca in the photosynthetic water oxidation reaction. The results include the first Mn, Ca and Sr X-ray spectroscopy studies using Ca or Sr-substituted PS II samples that established the presence of a MnCa heteronuclear structure and its orientation, and the most recent Sr X-ray spectroscopy study using biosynthetically prepared Sr-containing PS II in the various S-states that provide important insights into the requirement for Ca in the mechanism of the Mn4Ca catalytic center.

Yachandra, Vittal K.; Yano, Junko

2011-01-01

342

Phase distinction in semi-insulating polycrystalline silicon by pattern recognition of X-ray photoelectron spectroscopy/X-ray-induced Auger electron spectroscopy data  

NASA Astrophysics Data System (ADS)

X-ray photoelectron spectroscopy (XPS) and X-ray-induced Auger electron spectroscopy (XAES) supported with the lineshape analysis by the pattern recognition (PR) method and the fuzzy k-nearest neighbor rule ( kNN FR) were applied to study semiinsulating polycrystalline silicon layers (SIPOS). The aim of the present work was to obtain the qualitative and quantitative information about the surface region of as-received SIPOS layers. For the purpose of qualitative analysis the binding energies (BE), binding energy shifts (?BE), the half widths (FWHM) and the lineshapes of the Si 2p, O 1s and O KLL lines were analysed. The quantitative analysis was performed on the basis of the XPS using sensitivity factor method, multiline (ML) approach and the kNN FR. The performance of the kNN rule is possible after selecting the proper set of reference standard materials to which the rule refers during identification of an ambiguous chemical state. By selecting the reference samples supplying the information about the chemical state of Si, SiO x and SiO 2, the kNN rule allowed to distinguish qualitatively these three different phases in SIPOS samples. The particular application of the kNN FR makes possible the quantitative analysis by referring the fuzzy probability of classification for the given chemical state to the concentration of particular constituents in the investigated SIPOS. All the methods applied are consistent in revealing the quantitative results and show that SIPOS is a deeply non-homogeneous material, consisting of two phases: silicon and silicon oxide.

Lesiak, Beata; Zemek, Jozef; Jozwik, Adam

1998-09-01

343

High-brightness beamline for x-ray spectroscopy at the advanced light source  

SciTech Connect

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 goals of high energy resolution, high flux, and high brightness at the sample. When completed later this year, it will be the first ALS monochromatic hard-x-ray beamline, and its brightness will be an order-of-magnitude higher than presently available in this energy range. In addition, it will provide flux and resolution comparable to any other beamline now in operation. To achieve these goals, two technical improvements, relative to existing x-ray beamlines, were incorporated. First, a somewhat novel optical design for x rays, in which matched toroidal mirrors are positioned before and after the double-crystal monochromator, was adopted. This configuration allows for high resolution by passing a collimated beam through the monochromator, and for high brightness by focusing the ALS source on the sample with unit magnification. Second, a new Cowan type'' double-crystal monochromator based on the design used at NSLS beamline X-24A was developed. The measured mechanical precision of this new monochromator shows significant improvement over existing designs, without using positional feedback available with piezoelectric devices. Such precision is essential because of the high brightness of the radiation and the long distance (12 m) from the source (sample) to the collimating (focusing) mirror. This combination of features will provide a bright, high resolution, and stable x-ray beam for use in the x-ray spectroscopy program at the ALS.

Perera, R.C.C.; Jones, G. (Advanced Light Source, Lawrence Berkeley Laboratory, Berkeley, California 94720 (United States)); Lindle, D.W. (Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154-4003 (United States))

1995-02-01

344

High-brightness beamline for X-ray spectroscopy at the Advanced Light Source  

SciTech Connect

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 goals of high energy resolution, high flux, and high brightness at the sample. When completed later this year, it will be the first ALS monochromatic hard-x-ray beamline, and its brightness will be an order-of-magnitude higher than presently available in this energy range. In addition, it will provide flux and resolution comparable to any other beamline now in operation. To achieve these goals, two technical improvements, relative to existing x-ray beamlines, were incorporated. First, a somewhat novel optical design for x-rays, in which matched toroidal mirrors are positioned before and after the double-crystal monochromator, was adopted. This configuration allows for high resolution by passing a collimated beam through the monochromator, and for high brightness by focusing the ALS source on the sample with unit magnification. Second, a new ''Cowan type'' double-crystal monochromator based on the design used at NSLS beamline X-24A was developed. The measured mechanical precision of this new monochromator shows significant improvement over existing designs, without using positional feedback available with piezoelectric devices. Such precision is essential because of the high brightness of the radiation and the long distance (12m) from the source (sample) to the collimating (focusing) mirror. This combination of features will provide a bright, high resolution, and stable x-ray beam for use in the x-ray spectroscopy program at the ALS.

Perera, R.C.C.; Jones, G. [Lawrence Berkeley Lab., CA (US); Lindle, D.W. [Univ. of Nevada, Las Vegas, NV (US). Dept. of Chemistry

1994-08-01

345

Soft X-ray synchrotron radiation investigations of actinidematerials systems utilizing X-ray emission spectroscopy and resonantinelastic X-ray scattering  

SciTech Connect

Synchrotron radiation (SR) methods have been utilized with increasing frequency over the past several years to study topics in actinide science, ranging from those of a fundamental nature to those that address a specifically-targeted technical need. In particular, the emergence of microspectroscopic and fluorescence-based techniques have permitted investigations of actinide materials at sources of soft x-ray SR. Spectroscopic techniques with fluorescence-based detection are useful for actinide investigations since they are sensitive to small amounts of material and the information sampling depth may be varied. These characteristics also serve to simplify both sample preparation and safety considerations. Examples of investigations using these fluorescence techniques will be described along with their results, as well as the prospects for future investigations utilizing these methodologies.

Shuh, D.K.; Butorin, S.M.; Guo, J.-H.; Nordgren, J.

2004-01-03

346

Near-edge X-ray absorption fine structure spectroscopy as a tool for investigating nanomaterials.  

PubMed

We have demonstrated near-edge X-ray absorption fine structure (NEXAFS) spectroscopy as a particularly useful and effective technique for simultaneously probing the surface chemistry, surface molecular orientation, degree of order, and electronic structure of carbon nanotubes and related nanomaterials. Specifically, we employ NEXAFS in the study of single-walled carbon nanotube and multi-walled carbon nanotube powders, films, and arrays, as well as of boron nitride nanotubes. We have focused on the advantages of NEXAFS as an exciting, complementary tool to conventional microscopy and spectroscopy for providing chemical and structural information about nanoscale samples. PMID:17193550

Hemraj-Benny, Tirandai; Banerjee, Sarbajit; Sambasivan, Sharadha; Balasubramanian, Mahalingam; Fischer, Daniel A; Eres, Gyula; Puretzky, Alexander A; Geohegan, David B; Lowndes, Douglas H; Han, Weiqiang; Misewich, James A; Wong, Stanislaus S

2006-01-01

347

X-ray spectroscopy of the galaxy M87 - Radiative accretion of the hot plasma halo  

NASA Technical Reports Server (NTRS)

Canizares et al. (1979) have reported the detection of the O VIII Lyman-alpha line from the vicinity of the giant elliptical galaxy M87 in the Virgo cluster. The detection is based on high-resolution X-ray spectroscopy studies performed with the Focal Plane Crystal Spectrometer on the Einstein Observatory. The presence of a strong O VIII line indicates the existence of some material which is cooler than the bulk of the X-ray emitting gas surrounding M87. The result is interpreted as favoring models which call for radiative accretion of the hot gas onto M87. The present investigation is concerned with further high-resolution X-ray spectroscopy of M87. Seven additional emission line blends due primarily to ionized iron have been detected. These data make it possible to derive the approximate distribution of the quantity of emitting material over more than a decade in temperature for the central part of the M87 source. The obtained results are in excellent agreement with expectations for radiative, pressure driven accretion.

Canizares, C. R.; Clark, G. W.; Jernigan, J. G.; Markert, T. H.

1982-01-01

348

Study of exploding Al wire plasmas using X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy is a powerful diagnostic technique useful for determining the charge state, temperature and density of plasmas under a wide range of conditions and situations. Our particular interest was the study of the core-corona system generated in electrically exploded wires and wire array Z-pinches. Two wide-bandwidth spectrographs with flat and concave cylindrically bent KAP crystals, and high-resolution spectrographs with spherically bent quartz crystals have been used on the XP and COBRA pulsers at Cornell University. The hybrid X-pinch was used as the continuum x-ray source in the photon energy range of interest for absorption spectroscopy with exploding Al wire experiments. This source is capable of producing broadband continuum x-ray pulses with micron source size and 100 ps duration. Absorption spectra of single exploded Al wires and 2 - 4 wire arrays were recorded with high spatial resolution. The parameters of the dense wire core plasmas and the ablating plasma streams were estimated under different experimental conditions. New spectral features in absorption spectra were observed.

Pikuz, Sergey A.; Shelkovenko, Tatiana A.; Hoyt, Cad L.; Cahill, Adam D.; Hammer, David A.

2012-10-01

349

Multidimensional x-ray spectroscopy of valence and core excitations in cysteine  

PubMed Central

Several nonlinear spectroscopy experiments which employ broadband x-ray pulses to probe the coupling between localized core and delocalized valence excitation are simulated for the amino acid cysteine at the K-edges of oxygen and nitrogen and the K- and L-edges of sulfur. We focus on two-dimensional (2D) and 3D signals generated by two- and three-pulse stimulated x-ray Raman spectroscopy (SXRS) with frequency-dispersed probe. We show how the four-pulse x-ray signals \\documentclass[12pt]{minimal}\\begin{document}${\\bm k}_\\mathrm{I} =-{\\bm k} _1+{\\bm k} _2+{\\bm k} _3$\\end{document}kI=?k1+k2+k3 and \\documentclass[12pt]{minimal}\\begin{document}${\\bm k}_\\mathrm{II} ={\\bm k} _1-{\\bm k} _2+{\\bm k} _3$\\end{document}k II =k1?k2+k3 can give new 3D insight into the SXRS signals. The coupling between valence- and core-excited states can be visualized in three-dimensional plots, revealing the origin of the polarizability that controls the simpler pump-probe SXRS signals.

Biggs, Jason D.; Zhang, Yu; Healion, Daniel; Mukamel, Shaul

2013-01-01

350

X-ray absorption spectroscopy of cuprous-thiolate clusters in proteins and model systems  

SciTech Connect

Cuprous-thiolate multimetallic clusters exist in a range of different biological molecules for which no structural information exists from X-ray crystallography. Spectroscopic tools such as X-ray absorption spectroscopy have provided the major structural insights into this family of biological molecules. Recent nuclear magnetic resonance data on silver-substituted metallothionein, thought to be analogous with the copper proteins, have suggested the presence of digonal coordination. In order to test this in the copper case, we have examined a series of structurally characterized cuprous-thiolate model compounds, containing different proportions of digonal and trigonal copper sites, using copper K-edge X-ray absorption spectroscopy. The edge spectra, which have been previously used as a probe for the average copper coordination environment in proteins, show little variation between the models, indicating that these are not useful as a probe of coordination environment in the case of cuprous-thiolate clusters (as opposed to isolated metal sites). We show that systematic trends in the average Cu-S bond length from EXAFS curve-fitting analysis can be used to obtain an estimate of the fraction of digonal and trigonal copper sites. This correlation is applied to a series of different proteins containing cuprous-thiolate clusters which are found to contain significant fractions of digonal copper. 41 refs., 7 figs., 3 tabs.

Pickering, I.J.; George, G.N. (Stanford Univ., CA (United States)); Dameron, C.T.; Kurz, B.; Winge, D.R. (Univ. of Utah, Salt Lake City, UT (United States)); Dance, I.G. (Univ. of New South Wales, Kensington (Australia))

1993-10-20

351

Surface Arsenic Speciation of a Drinking-Water Treatment Residual Using X-Ray Absorption Spectroscopy  

SciTech Connect

Drinking-water treatment residuals (WTRs) present a low-cost geosorbent for As-contaminated waters and soils. Previous work has demonstrated the high affinity of WTRs for As, but data pertaining to the stability of sorbed As is missing. Sorption/desorption and X-ray absorption spectroscopy (XAS), both XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) studies, were combined to determine the stability of As sorbed by an Fe-based WTR. Arsenic(V) and As(III) sorption kinetics were biphasic in nature, sorbing <90% of the initial added As (15,000 mg kg{sup -1}) after 48 h of reaction. Subsequent desorption experiments with a high P load (7500 mg kg{sup -1}) showed negligible As desorption for both As species, approximately <3.5% of sorbed As; the small amount of desorbed As was attributed to the abundance of sorption sites. XANES data showed that sorption kinetics for either As(III) or As(V) initially added to solution had no effect on the sorbed As oxidation state. EXAFS spectroscopy suggested that As added either as As(III) or as As(V) formed inner-sphere mononuclear, bidentate complexes, suggesting the stability of the sorbed As, which was further corroborated by the minimum As desorption from the Fe-WTR.

Makris, K.C.; Sarkar, D.; Parsons, J.G.; Datta, R.; Gardea-Torresdey, J.L.

2009-06-03

352

X-ray sensitive charge-coupled device instrumentation for short and ultrashort pulse laser-produced plasma experiments  

SciTech Connect

We describe the use of x-ray sensitive charge-coupled device (CCD) detectors for measuring the 1--15 A emission from high temperature plasmas produced at the [ital L]-Division JANUS and USP (pulse length[similar to]100 fs) laser facilities. Instruments based upon commercially available video format cameras have been designed to replace x-ray film, as the two-dimensional recording medium, for imaging and x-ray spectroscopic applications. Used in conjunction with a high sensitivity x-ray pinhole camera, magnification 5--20, the CCD detectors can give spatial resolution approaching 5 [mu]m and energy band information by the use of edge filters. A compact wavelength dispersive spectrometer equipped with the CCD detector and a flat Bragg crystal analyzer can record survey spectra.

Dunn, J.; Young, B.K.F.; Shiromizu, S.J. (L-Division, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551 (United States))

1995-01-01

353

Microcalorimeters for High Resolution X-Ray Spectroscopy of Laboratory and Astrophysical Plasmas  

NASA Technical Reports Server (NTRS)

The proposal has three major objectives. The first focuses on advanced neutron-transmutation-doped (NTD)-based microcalorimeter development. Our goal is to develop an array of microcalorimeters with sub- 5 eV energy resolution that can operate with pile-up-free throughput of at least 100 Hz per pixel. The second objective is to establish our microcalorimeter as an essential x-ray diagnostic for laboratory astrophysics studies. We propose to develop a dedicated microcalorimeter spectrometer for the EBIT (electron beam ion trap). This instrument will incorporate the latest detector and cryogenic technology that we have available. The third objective is to investigate innovative ideas related to possible flight opportunities. These include compact, long lived cryo-systems, ultra-low temperature cold stages, low mass and low power electronics, and novel assemblies of thin windows with high x-ray transmission.

Silver, E.; Flowers, Bobby J. (Technical Monitor)

2003-01-01

354

A new family of swept charge devices (SCDs) for x-ray spectroscopy applications  

NASA Astrophysics Data System (ADS)

In this paper we discuss the design and performance of a new family of swept charge devices intended for X-ray spectroscopy. The devices were designed to combine large area with good detection efficiency over the 0.5-10 keV band, and, importantly, to be capable of operation at "warm" temperatures, e.g. room temperature. Three types of device have been manufactured ranging in detection area from 5-420 mm2 and the paper discusses the initial characterisation of the detectors over a range of temperatures. Whilst the device leakage current scales with detector area, we demonstrate that the smallest detector is capable of yielding Fano-limited X-ray spectra at room temperature, whereas the largest requires modest cooling down to -20°C to achieve this resolution.

Holland, Andrew; Pool, Peter

2008-08-01

355

RXTE timing and spectroscopy of a black hole X-ray binary in outburst  

NASA Technical Reports Server (NTRS)

Under this program, RXTE observed the Galactic black hole candidate X-ray binary H1743-322. Observations were made simultaneously in the X-ray and radio bands with Chandra and the VLA, respectively. First results from this multi-wavelength study have been reported in two papers published in refereed journals, one focusing on timing results and the other focusing on spectroscopy. The timing studies revealed high frequency QPOs at approximately 180 Hz and 240 Hz, likely in a 2:3 frequency ratio as predicted by some models. The RXTE spectra were remarkable in that they showed no evidence of disk reflection or line emission, both of which are expected in black holes.

Miller, Jon; Swank, Jean (Technical Monitor)

2005-01-01

356

X-ray fluorescence/Auger-electron coincidence spectroscopy of vacancy cascades in atomic argon  

SciTech Connect

Argon L{sub 2.3}-M{sub 2.3}M{sub 2.3} Auger-electron spectra were measured in coincidence with K{alpha} fluorescent x-rays in studies of Ar K-shell vacancy decays at several photon energies above the K-threshold and on the 1s-4p resonance in atomic argon. The complex spectra recorded by conventional electron spectroscopy are greatly simplified when recorded in coincidence with fluorescent x-rays, allowing a more detailed analysis of the vacancy cascade process. The resulting coincidence spectra are compared with Hartree-Fock calculations which include shake-up transitions in the resonant case. Small energy shifts of the coincidence electron spectra are attributed to post-collision interaction with 1s photoelectrons.

Arp, U. [National Inst. of Standards and Technology, Gaithersburg, MD (United States). Electron and Optical Physics Div.; LeBrun, T.; Southworth, S.H.; Jung, M. [Argonne National Lab., IL (United States). Physics Div.; MacDonald, M.A. [E.P.S.R.C. Daresbury Lab., Warrington (United Kingdom)

1996-12-01

357

In situ x-ray photoelectron spectroscopy for electrochemical reactions in ordinary solvents  

SciTech Connect

In situ electrochemical X-ray photoelectron spectroscopy (XPS) apparatus, which allows XPS at solid/liquid interfaces under potential control, was constructed utilizing a microcell with an ultra-thin Si membrane, which separates vacuum and a solution. Hard X-rays from a synchrotron source penetrate into the Si membrane surface exposed to the solution. Electrons emitted at the Si/solution interface can pass through the membrane and be analyzed by an analyzer placed in vacuum. Its operation was demonstrated for potential-induced Si oxide growth in water. Effect of potential and time on the thickness of Si and Si oxide layers was quantitatively determined at sub-nanometer resolution.

Masuda, Takuya [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012 (Japan); Yoshikawa, Hideki; Kobata, Masaaki; Kobayashi, Keisuke [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), Sayo, Hyogo 679-5148 (Japan)] [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), Sayo, Hyogo 679-5148 (Japan); Noguchi, Hidenori [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan); Kawasaki, Tadahiro [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603 (Japan)] [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603 (Japan); Uosaki, Kohei [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan)

2013-09-09

358

Application of X-ray Fluorescence Spectroscopy in Analysis of Oil Paint Pigments  

NASA Astrophysics Data System (ADS)

X-ray Fluorescence (XRF) spectroscopy is a rapid, noninvasive technique for both detecting and identifying chemical elements within a given sample. At North Georgia College and State University, a sealed tube x-ray source and slightly focusing polycapillary optic are used in nondestructive XRF analysis of oil paint pigments. Oil paints contain both organic and inorganic matter, and the inorganic ingredients such as titanium, vanadium, iron, zinc, and other elements are easily detected by XRF, which can be used to uniquely differentiate between various paint pigments. To calibrate the XRF system for paint color identification, six different colors of oil paint were fluoresced and identified based off of their characteristic spectra. By scanning the paint sample in two dimensions, the characteristic XRF spectra obtained were compiled to produce an XRF replica of the painting.

Major, Cassandra; Formica, Sarah

2011-10-01

359

Stability and transformation mechanism of weddellite nanocrystals studied by X-ray diffraction and infrared spectroscopy.  

PubMed

This study is focused on the stability of weddellite, the dihydrate phase of calcium oxalate [CaC(2)O(4)·(2 + x)H(2)O], mainly detected in kidney stones and in oxalate films found on the surfaces of several ancient monuments. Its occurrence is a critical issue since, at environmental conditions, weddellite is unstable and quickly changes into whewellite, the monohydrate phase of calcium oxalate (CaC(2)O(4)·H(2)O). New single crystal X-ray diffraction experiments have been carried out, which confirm the structural model of weddellite previously published. Synthesised nanocrystals of weddellite have been kept under different hygrometric conditions in order to study, by X-ray powder diffraction, the influence of humidity on their stability. Moreover, the mechanism of transformation of weddellite nanocrystals has been investigated by infrared spectroscopy using D(2)O as a structural probe. PMID:20931117

Conti, Claudia; Brambilla, Luigi; Colombo, Chiara; Dellasega, David; Gatta, G Diego; Realini, Marco; Zerbi, Giuseppe

2010-11-21

360

Optical Spectroscopy of High-Mass X-ray Binaries in the Small Magellanic Cloud  

NASA Astrophysics Data System (ADS)

We present results from optical spectroscopy of HMXBs in the SMC selected from Chandra and XMM-Newton surveys. We acquired 21 spectra for low-luminosity X-ray sources (Lx<10^34 erg/s), well below the typical luminosities of outbursting BeXRBs. We find that their spectral types are in the B0-B9 range, with most objects being of later types. One of them is a new Supergiant X-ray binary, the second such system identified in the SMC. Its optical counterpart is the well-known SgB[e] (and probable LBV) star S-18. With this study we raise the sample of BeXRBs with available spectral types to 52 objects. While our results are in agreement with previous studies, we find systematically later spectral types. This might be the result of extending our sample of BeXRBs to fainter sources.

Maravelias, Grigoris

2012-07-01

361

Time-dependent density functional theory applied to x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

We report the implementation of a time-dependent density functional theory (TDDFT) method in the adiabatic limit (TDLDA) of the calculation of x-ray absorption spectroscopy. We show results for various choices for the exchange-correlation kernel, in particular the absorption spectra at the L2,3 edges of the 3d elements. We equally present a detailed study of the method's limitations and range of applicability. We found that TDDFT calculations should be performed fully relativistically even for nonmagnetic materials. We conclude that an accurate TDDFT description of x-ray absorption should include the core hole effects. The local (both in space and time) TDDFT kernels that are currently used in the description of extended systems do not meet this criterion.

Bun?u, Oana; Joly, Yves

2012-04-01

362

Structure, X-ray photoelectron spectroscopy and photoluminescence properties of highly ordered ZnO microrods  

NASA Astrophysics Data System (ADS)

ZnO microrods were grown by aqueous bath synthesis at 90 °C and annealed at 400 °C in air. Both scanning electron micrographs and X-ray diffraction patterns indicate that the ZnO microrods are wurtzite crystallographic phase with metastable (0 0 2) preferred orientation. X-ray photoelectron spectroscopy spectra show that Zn 2p and O 1s spectra mainly originate from the Zn 2+ and O 2- ions in Zn-O bonds, respectively. Photoluminescence spectra of ZnO microrods are dominated by outstanding ultraviolet (UV) emission bands, which are attributed to the first, the second or the third longitudinal optical phonon replicas of free-exciton (E FX) emission. The degeneration of (0 0 2) crystalline planes causes the intensity decline and the redshift of UV emission peaks in the ZnO microrods.

Yang, Xiao-Jie; Miao, Xin-Yu; Xu, Xiao-Liang; Xu, Chuan-Ming; Xu, Jun; Liu, Hong-Tu

2005-09-01

363

Wiggler-base Hard X-ray Spectroscopy Beamline at CLS  

NASA Astrophysics Data System (ADS)

The CLS 06ID-1 Hard X-ray Micro-Analysis Beamline (HXMA) is a general purpose hard X-ray spectroscopy beamline (5 to 40 keV) designed to serve users in XAFS, diffraction and microprobe communities. The beamline uses the synchrotron radiation from a superconducting wiggler. The primary beamline optics include a 1.2 m water-cooled silicon collimating mirror (separate Rh and Pt coating stripes), a liquid nitrogen cooled double crystal monochromator (Kohzu CMJ-1) housing two crystal pairs (Si 111 and 220), and a 1.15 m long water-cooled silicon toroidal focusing mirror (separate Rh and Pt coating stripes). All mirrors are equipped with dynamical meridian benders. The experimental hutch hosts three experimental setups for XAFS, diffraction and microprobe, respectively. Primary design considerations and some commissioning results are discussed.

Jiang, D. T.; Chen, N.; Sheng, W.

2007-01-01

364

The nature of arsenic in uranium mill tailings by X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

In order to understand the evolving world of environmental issues, the ability to characterize and predict the stability and bioavailability of heavy métal contaminants in mine waste is becoming increasingly more important. X-ray Absorption Near Edge Structure (XANES) and Extended X-ray Absorption Fine Structure (EXAFS) spectroscopies were used to characterize a series of synthetic and natural samples associated with mine tailings processing. XANES was shown to be excellent as a tool to rapidly differentiate oxidation states of arsenic within the samples. The EXAFS spectra provided information on the mineralogy of the precipitated raffinate and tailings and showed that these samples are composed of a mixture of amorphous ferric arsenates, adsorbed arsenates and a mixture of other poorly ordered arsenates.

Cutler, J. N.; Chen, N.; Jiang, D. T.; Demopoulos, G. P.; Jia, Y.; Rowson, J. W.

2003-05-01

365

The effect of X-ray photoelectron spectroscopy measurement on P(VDF-TrFE) copolymer thin films  

NASA Astrophysics Data System (ADS)

The impact of prolonged X-ray irradiation during X-ray photoelectron spectroscopy (XPS) measurement was investigated on poly(vinylidene-trifluoroethylene) (P(VDF-TrFE)) thin films. It was observed that prolonged X-ray irradiation can accelerate the crosslinking of P(VDF-TrFE) and diminish the ferroelectric phase. Fourier transform infrared spectroscopy (FT-IR) data indicate that the ferroelectric phase diminishes completely after 360 kJ of X-ray irradiation dose and it induces the paraelectric phase. In this work, the main emphasis was given to the optimization of the X-ray irradiation dose during XPS measurements to maintain the ferroelectric phase within the copolymer films.

Mandal, Dipankar; Müller, Klaus; Henkel, Karsten; Schmeißer, Dieter

2012-11-01

366

Imaging x-ray sources at a finite distance in coded-mask instruments  

SciTech Connect

We present a method for the correction of beam divergence in finite distance sources imaging through coded-mask instruments. We discuss the defocusing artifacts induced by the finite distance showing two different approaches to remove such spurious effects. We applied our method to one-dimensional (1D) coded-mask systems, although it is also applicable in two-dimensional systems. We provide a detailed mathematical description of the adopted method and of the systematics introduced in the reconstructed image (e.g., the fraction of source flux collected in the reconstructed peak counts). The accuracy of this method was tested by simulating pointlike and extended sources at a finite distance with the instrumental setup of the SuperAGILE experiment, the 1D coded-mask x-ray imager onboard the AGILE (Astro-rivelatore Gamma a Immagini Leggero) mission. We obtained reconstructed images of good quality and high source location accuracy. Finally we show the results obtained by applying this method to real data collected during the calibration campaign of SuperAGILE. Our method was demonstrated to be a powerful tool to investigate the imaging response of the experiment, particularly the absorption due to the materials intercepting the line of sight of the instrument and the conversion between detector pixel and sky direction.

Donnarumma, Immacolata; Pacciani, Luigi; Lapshov, Igor; Evangelista, Yuri

2008-07-01

367

Imaging x-ray sources at a finite distance in coded-mask instruments.  

PubMed

We present a method for the correction of beam divergence in finite distance sources imaging through coded-mask instruments. We discuss the defocusing artifacts induced by the finite distance showing two different approaches to remove such spurious effects. We applied our method to one-dimensional (1D) coded-mask systems, although it is also applicable in two-dimensional systems. We provide a detailed mathematical description of the adopted method and of the systematics introduced in the reconstructed image (e.g., the fraction of source flux collected in the reconstructed peak counts). The accuracy of this method was tested by simulating pointlike and extended sources at a finite distance with the instrumental setup of the SuperAGILE experiment, the 1D coded-mask x-ray imager onboard the AGILE (Astro-rivelatore Gamma a Immagini Leggero) mission. We obtained reconstructed images of good quality and high source location accuracy. Finally we show the results obtained by applying this method to real data collected during the calibration campaign of SuperAGILE. Our method was demonstrated to be a powerful tool to investigate the imaging response of the experiment, particularly the absorption due to the materials intercepting the line of sight of the instrument and the conversion between detector pixel and sky direction. PMID:18594598

Donnarumma, Immacolata; Pacciani, Luigi; Lapshov, Igor; Evangelista, Yuri

2008-07-01

368

The use of X?ray absorption spectroscopy for monitoring the thickness of antiwear films from ZDDP  

Microsoft Academic Search

X?ray absorption near edge structure (XANES) spectroscopy at the P K?edge was used to monitor ZDDP antiwear film thickness\\u000a with rubbing time. Thermal immersion films of varying thickness were generated from the ZDDP and analysed using XANES spectroscopy\\u000a and the particle induced X?ray emission (PIXE) technique. P K?edge XANES edge jumps and (1s ? np) peak heights of the spectra

M. L. Suominen Fuller; L. Rodriguez Fernandez; G. R. Massoumi; W. N. Lennard; M. Kasrai; G. M. Bancroft

2000-01-01

369

Resistive switching in Cr-doped SrTiO 3: An X-ray absorption spectroscopy study  

Microsoft Academic Search

X-ray absorption spectroscopy was used to study the microscopic origin of conductance and resistive switching in chromium-doped strontium titanate (Cr:SrTiO3). Differences in the X-ray absorption near edge spectroscopy (XANES) at the Cr K-edge indicate that the valence of Cr changes from 3+ to 4+ underneath the anode of our sample device after the application of an electric field. Spatially resolved

B. P. Andreasson; M. Janousch; U. Staub; G. I. Meijer; B. Delley

2007-01-01

370

A Monolithic Array of 77 Silicon Drift Detectors for X-Ray Spectroscopy and Gamma-Ray Imaging Applications  

Microsoft Academic Search

Monolithic arrays of Silicon Drift Detectors (SDDs) have been employed successfully in X-ray spectroscopy and$gamma$-ray imaging applications. Thanks to the low electronics noise achieved at short shaping time, the SDD is an ideal device for high-resolution and high-rate X-ray spectroscopy experiments at synchrotron sources. Moreover, small monolithic arrays of SDDs have also been used as photodetector of the scintillation light

C. Fiorini; M. Bellini; A. Gola; A. Longoni; F. Perotti; P. Lechner; H. Soltau; L. Struder

2005-01-01

371

Electronic Properties of Hydrogen Storage Materials with Photon-in/Photon-out Soft-X-Ray Spectroscopy  

SciTech Connect

The applications of resonant soft X-ray emission spectroscopy on a variety of carbon systems have yielded characteristic fingerprints. With high-resolution monochromatized synchrotron radiation excitation, resonant inelastic X-ray scattering has emerged as a new source of information about electronic structure and excitation dynamics. Photon-in/photon-out soft-X-ray spectroscopy is used to study the electronic properties of fundamental materials, nanostructure, and complex hydrides and will offer potential in-depth understanding of chemisorption and/or physisorption mechanisms of hydrogen adsorption/desorption capacity and kinetics.

Guo, Jinghua

2008-09-22

372

Inner-shell photoionization spectroscopy on deposited metal clusters using soft x-ray synchrotron radiation: An experimental setup  

SciTech Connect

Exploration of mass-selected clusters by soft x-ray synchrotron radiation is well suited to receive element specific information on clusters in contact with a support and to systematically follow the evolution of size-dependent electronic and geometrical properties from the smallest clusters toward the bulk. Here we describe an experimental setup, which combines cluster synthesis, mass selection, soft landing, ultrahigh vacuum transfer, and photoionization experiments such as x-ray photoelectron spectroscopy, x-ray absorption, and Auger electron spectroscopy. First spectroscopic results and experimental conditions are briefly discussed for Cu{sub 19} deposited onto the natural oxide layer of a Si-wafer surface.

Peters, S.; Peredkov, S.; Balkaya, B.; Ferretti, N.; Savci, A.; Vollmer, A.; Neeb, M.; Eberhardt, W. [Helmholtz-Zentrum Berlin fuer Materialien und Energie, Wilhelm-Conrad-Roentgen-Campus Adlershof, Elektronenspeicherring BESSY II, Albert-Einstein Strasse 15, D-12489 Berlin (Germany)

2009-12-15

373

The focusing optics x-ray solar imager (FOXSI): instrument and first flight  

NASA Astrophysics Data System (ADS)

Solar flares accelerate particles up to high energies (MeV and GeV scales for electrons and ions, respectively) through efficient acceleration processes that are not currently understood. Hard X-rays (HXRs) are the most direct diagnostic of flare-accelerated electrons. However, past and current solar HXR observers lack the necessary sensitivity and imaging dynamic range to make detailed studies of faint HXR sources in the solar corona (where particle acceleration is thought to occur); these limitations are mainly due to the indirect Fourier imaging techniques used by these observers. With greater sensitivity and dynamic range, electron acceleration sites could be systematically studied in detail. Both these capabilities can be advanced by the use of direct focusing optics. The recently own Focusing Optics X-ray Solar Imager (FOXSI) sounding rocket payload demonstrates the unique diagnostic power of focusing optics for observations of solar HXRs. FOXSI features grazing-incidence replicated nickel optics with 5 arcsecond resolution and fine-pitch silicon strip detectors with a 7.7 arcsecond strip pitch. FOXSI flew successfully on 2012 November 2, producing images and spectra of a microflare and performing a search for non-thermal emission (4{15 keV) from nanoflares occurring outside active regions in the quiet Sun. A future spacecraft version of FOXSI, featuring similar optics and detectors, could make detailed observations of HXRs from flare-accelerated electrons, identifying and characterizing particle acceleration sites and mapping out paths of energetic electrons as they leave these sites and propagate throughout the solar corona. This paper will describe the FOXSI instrument and present images from the first flight.

Krucker, Säm.; Christe, Steven; Glesener, Lindsay; Ishikawa, Shinnosuke; Ramsey, Brian; Gubarev, Mikhail; Saito, Shinya; Takahashi, Tadayuki; Watanabe, Shin; Tajima, Hiroyasu; Tanaka, Takaaki; Turin, Paul; Glaser, David; Fermin, Jose; Lin, Robert P.

2013-09-01

374

Laboratory x-ray spectroscopy experiments in support of NASA`s x-ray satellite missions  

SciTech Connect

With support from NASA, we are performing a series of laboratory astrophysics investigations designed to address fundamental uncertainties in basic atomic physics processes relevant to the interpretation of discrete X-ray spectra of cosmic plasmas. Moderate resolution spectra acquired by the ASCA Observatory already demonstrate the inadequacy of currently available spectral modelling codes for this wavelength band. With the upcoming launches of AXAF, XMM, ASTRO E, and Spektrum Roentgen-Gamma, the demand for significant advances in this field will increase dramatically. Our program is based on the exploitation of the Electron Beam Ion Trap facility at the Lawrence Livermore National Laboratory, and a unique set of spectrometers and experimental techiques specifically developed for this purpose. Recent experiments have been devoted to definitive measurements of line emissivities for iron L-shell ions in optically thin, collisional plasmas.

Kahn, S. M., Columbia University

1998-05-22

375

CHANDRA GRATING SPECTROSCOPY OF THE Be/X-RAY BINARY 1A 0535+262  

SciTech Connect

We present Chandra HETGS spectroscopy of the Be/X-ray binary 1A 0535+262 obtained during the 2009/2010 giant outburst. These are the first CCD grating spectra of this type of system during a giant outburst. Our spectra reveal a number of lines including a narrow Fe K{alpha} emission line with an FWHM of {approx}5000 km s{sup -1}. For the first time, we detect the presence of a highly ionized outflow in a Be/X-ray binary. Assuming that the line is He-like Fe XXV, fits with a simple Gaussian imply an outflow velocity of {approx}1500 km s{sup -1}. However, self-consistent photoionization modeling with XSTAR suggests that Fe XXIII-XXIV must also contribute. In this case, an outflow velocity of {approx}3000 km s{sup -1} is implied. These results are discussed in the context of accretion flow in Be-star, neutron star, and black hole X-ray binaries.

Reynolds, Mark T.; Miller, Jon M., E-mail: markrey@umich.ed [Department of Astronomy, University of Michigan, 500 Church Street, Ann Arbor, MI 48109 (United States)

2010-11-10

376

Polarized x-ray absorption spectroscopy for the study of superconductors and magnetic materials  

NASA Astrophysics Data System (ADS)

Synchrotron radiation is a good source of polarized radiation in the x-ray regime. The radiation obtained from a bending magnet source is linearly polarized in the bending plane and has a varying degree of circular polarization away from the bending plane. This feature of synchrotron radiation can be taken advantage of with proper optics to selectively use the type of polarized radiation required for the experiment in question. Linear polarized radiation is used to study the anisotropic nature of electronic and atomic structure by x-ray absorption techniques from single crystal and oriented powder samples. We will give a specific example of the use of linearly polarized x-ray absorption spectroscopy measurements for the study of the magnetically oriented layered copper oxide superconductors. While such linear dichroism measurements help identify the symmetry of the empty electronic states, circular dichroism measurements in magnetic systems help in determining the spin contribution to the absorption process. We will discuss magnetic circular dichroism measurements of the ordered-disordered invar alloy Fe(subscript 3)Pt.

Ramanathan, Mohan; Alp, Esen E.; Mini, Susan M.; Salem-Sugui, S.; Bommannavar, A.

1991-11-01

377

The amorphous Zn biomineralization at Naracauli stream, Sardinia: electron microscopy and X-ray absorption spectroscopy.  

PubMed

An amorphous Zn biomineralization ("white mud"), occurring at Naracauli stream, Sardinia, in association with cyanobacteria Leptolyngbya frigida and diatoms, was investigated by electron microscopy and X-ray absorption spectroscopy. Preliminary diffraction analysis shows that the precipitate sampled on Naracauli stream bed is mainly amorphous, with some peaks ascribable to quartz and phyllosilicates, plus few minor unattributed peaks. Scanning electron microscopy analysis shows that the white mud, precipitated in association with a seasonal biofilm, is made of sheaths rich in Zn, Si, and O, plus filaments likely made of organic matter. Transmission electron microscopy analysis shows that the sheaths are made of smaller units having a size in the range between 100 and 200 nm. X-ray absorption near-edge structure and extended X-ray absorption fine structure data collected at the Zn K-edge indicate that the biomineral has a local structure similar to hemimorphite, a zinc sorosilicate. The differences of this biomineral with respect to the hydrozincite biomineralization documented about 3 km upstream in the same Naracauli stream may be related to either variations in the physicochemical parameters and/or different metabolic behavior of the involved biota. PMID:23832800

Medas, D; Lattanzi, P; Podda, F; Meneghini, C; Trapananti, A; Sprocati, A; Casu, M A; Musu, E; De Giudici, G

2014-06-01

378

The Constellation-X Spectroscopy X-ray Telescope: Recent Technology Development  

NASA Technical Reports Server (NTRS)

We describe recent progress in the technology development program for the mirror system for the Constellation-X Spectroscopy X-ray Telescope (SXT). Development of this mirror represents a significant technology challenge, as it must provide a combination of large effective area (3 sq. m) and modest angular resolution (15 arc second half power diameter requirement; 5 arc second goal) with a limited mass allocation. The baseline design incorporates over 200 nested Wolter 1 mirrors. Each of these in turn is segmented in order to simplify handling of the mirrors and facilitate mass production. The X-ray reflecting surfaces are fabricated from thin, thermally formed glass sheets. Production improvements have yielded mirror segments that approach the performance requirement without the need for epoxy replication. A mounting and alignment approach incorporating piezoelectric actuators has been shown to manipulate mirror segments with the required precision without introducing significant distortion. Substantial improvements in metrology methodology have provided insights into the mirror segment forming and alignment processes. An X-ray demonstration of a mirror segment pair is planned for early 2006.

Petre, Robert; Lehan, John L.; Owens, Scott; Saha, Timo; Stewart, Jeff; Zhang, William W.; O'Dell, Stephen L.; Jones, Wiliam D.; Reid, Paul B.

2006-01-01

379

Diamond sensors and polycapillary lenses for X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Diamond sensors are evaluated as incident beam monitors for X-ray absorption spectroscopy experiments. These single crystal devices pose a challenge for an energy-scanning experiment using hard X-rays due to the effect of diffraction from the crystalline sensor at energies which meet the Bragg condition. This problem is eliminated by combination with polycapillary lenses. The convergence angle of the beam exiting the lens is large compared to rocking curve widths of the diamond. A ray exiting one capillary from the lens meets the Bragg condition for any reflection at a different energy from the rays exiting adjacent capillaries. This serves to broaden each diffraction peak over a wide energy range, allowing linear measurement of incident intensity over the range of the energy scan. Extended X-ray absorption fine structure data are measured with a combination of a polycapillary lens and a diamond incident beam monitor. These data are of comparable quality to data measured without a lens and with an ionization chamber monitoring the incident beam intensity.

Ravel, B.; Attenkofer, K.; Bohon, J.; Muller, E.; Smedley, J.

2013-10-01

380

Diamond sensors and polycapillary lenses for X-ray absorption spectroscopy.  

PubMed

Diamond sensors are evaluated as incident beam monitors for X-ray absorption spectroscopy experiments. These single crystal devices pose a challenge for an energy-scanning experiment using hard X-rays due to the effect of diffraction from the crystalline sensor at energies which meet the Bragg condition. This problem is eliminated by combination with polycapillary lenses. The convergence angle of the beam exiting the lens is large compared to rocking curve widths of the diamond. A ray exiting one capillary from the lens meets the Bragg condition for any reflection at a different energy from the rays exiting adjacent capillaries. This serves to broaden each diffraction peak over a wide energy range, allowing linear measurement of incident intensity over the range of the energy scan. Extended X-ray absorption fine structure data are measured with a combination of a polycapillary lens and a diamond incident beam monitor. These data are of comparable quality to data measured without a lens and with an ionization chamber monitoring the incident beam intensity. PMID:24182100

Ravel, B; Attenkofer, K; Bohon, J; Muller, E; Smedley, J

2013-10-01

381

Compact focusing von Hamos spectrometer for quantitative x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

A compact focusing crystal spectrometer based on the von Hamos scheme is described. Cylindrically curved mica and graphite crystals with a radius of curvature of R=20 mm are used in the spectrometer. A front illuminated charge-coupled device (CCD) linear array detector makes this spectrometer useful for real-time spectroscopy of laser-produced plasma x-ray sources within the wavelength range of ?=1.8-10 Å. Calibration of crystals and the CCD linear array makes it possible to measure absolute photon fluxes. X-ray spectra in an absolute intensity scale were obtained from Mg, Ti, and Fe laser-produced plasmas, with a spectral resolution ?/??=800-2000 for the mica and ?/??=200-300 for graphite crystal spectrometers. The spectrometer has high efficiency in a wide spectral range, it is compact (40 mm diam, 150 mm length), easy to align, and flexible. The spectrometer is promising for absolute spectral measurements of x-ray radiation of low-intensity sources (femtosecond laser-produced plasmas, micropinches, electron-beam-ion-trap sources, etc.).

Shevelko, A. P.; Kasyanov, Yu. S.; Yakushev, O. F.; Knight, L. V.

2002-10-01

382

Electron-ion interaction cross sections determined by x-ray spectroscopy on EBIT  

SciTech Connect

The Livermore electron beam ion trap (EBIT) is used to measure electron-ion interactions with high-resolution x-ray spectroscopy. Measurements are presented of the K{alpha} x-ray emission of heliumlike Fe{sup 24+} that demonstrate the effect of various processes on the spectrum of highly charged heliumlike ions. In particular, we have studied how dielectronic recombination into high-n Rydberg levels and resonance excitation processes contribute to the x-ray emission near threshold for direct electron-impact excitation. From these and other measurements we infer the cross sections for impact excitation of heliumlike titanium, chromium, manganese, and iron. Comparing the results with theoretical cross sections from distorted-wave calculations we find excellent agreement for all transitions but the heliumlike resonance transition from 1s2p {sup 1}P{sub 1} to ground, whose excitation cross section is measured to be 10%--20% smaller than calculated. 36 refs., 6 figs., 1 tab.

Beiersdorfer, P.; Cauble, R.; Chantrenne, S.; Chen, M.; Knapp, D.; Marrs, R.; Phillips, T.; Reed, K.; Schneider, M.; Scofield, J.; Wong, K.; Vogel, D.; Zasadzinski, R. (Lawrence Livermore National Lab., CA (USA)); Wargelin, B. (California Univ., Berkeley, CA (USA). Space Sciences Lab.); Bitter, M.; von Goeler, S. (Princeton Univ., NJ (USA). Plasma Physics Lab.)

1991-06-26

383

X-ray spectroscopy of laser-produced plasmas using a von Hamos spectrograph  

NASA Astrophysics Data System (ADS)

The design and characteristics of a von Hamos spectrograph are considered. Efficiency of the von Hamos mica crystal spectrograph is absolutely calibrated using laser-produced plasmas as an x-ray source and a p-i-n diode as a detector. The value of integrated reflectivity of the mica crystal is also determined in the same spectral bands and diffraction orders: 5.5 - 11 angstrom (first order), 2.6 - 5.0 angstrom (second order), 1.84 - 3.22 angstrom (third order), 1.84 - 2.65 angstrom (fourth order), 1.84 - 1.92 angstrom (fifth order). The von Hamos spectrograph is used for x-ray spectroscopy and radiometry of laser-produced plasmas. The spectrograph possesses several advantages of interest: high spectral resolution ((lambda) /(delta) (lambda) up to 3000), a direct registration of one or two dimensional source images (spatial resolution up to 10 micrometers) and a high detecting efficiency over a wide spectral range. Focused intensities could be 10(superscript 2) - 10(superscript 3) times higher than those of flat crystal spectrographs. This type of spectrograph is ideal for the recording of the wide-range x-ray spectra of low intensity sources such as the femtosecond laser-produced plasma, micropinch, electron beam ion trap (EBIT), and others.

Shevelko, A. P.

1998-06-01

384

Tracking electrons and atoms in a photoexcited metalloporphyrin by x-ray transient absorption spectroscopy.  

SciTech Connect

Simultaneously tracking electronic and molecular structures of a photoexcited metalloporphyrin, present for only 200 ps in a dilute solution, has been realized using X-ray transient absorption spectroscopy (XTA). Using laser pulses as excitation sources and delayed X-ray pulses as probes, we were able to identify the excited state electronic configuration of a nickel porphyrin as singly occupied 3dx2-y2 and 3dz2 molecular orbitals (MOs) with an energy gap of {approx}2.2 eV, and energy shifts 4pz MOs to 1.5 eV higher relative to that of the ground state, and an expanded porphyrin ring characterized by lengthening of Ni-N and Ni-C bonds. Moreover, kinetic XTA signals at different X-ray photon energies demonstrate the capability for acquiring the correlation and coherence between different optically excited states with the same technique. These results provide guidance for theoretical calculations as well as insightful understanding of optically excited states that play important roles in photochemical processes.

Chen, L. X.; Zhang, X.; Wasinger, E. C.; Attenkofer, K.; Jennings, G.; Muresan, A. Z.; Lindsey, J. S.; North Carolina State

2007-01-01

385

In Situ X-Ray Absorption Spectroscopy Study of the LiNiO2 Electrode  

NASA Astrophysics Data System (ADS)

LiNiO2 is one of the most promising active material for the development of novel 4V rechargeable lithium batteries. Recent x-ray diffraction studies showed that the electrochemical reactivity of this electrode is sensitive to the structure of the starting material as well as the charged products. To further examine this material, we have conducted an x-ray absorption spectroscopy (XAS) study to determine the structure of this electrode as a function of its charge state. Specifically, the x-ray absorption Ni K-edge energy, the pre-edge structure, and local structure parameters such as bond lengths, coordination numbers and disorders were investigated at various states of charge corresponding to Li_(1-x)NiO2 for x values of 0.0, 0.11, 0.23, 0.34, 0.45, 0.82, and 0.99. The charging which proceeds via lithium de-intercalation was conducted using constant current anodization at 0.5 mA in a non aqueous electrolyte consisting of 1M LiPF6 in 1:1:3 propylene ! carbonate, ethylene carbonate and dimethyl carbonate. The XAS results for this electrode will be compared with those of ?-NiOOH and KNiIO_6, the latter being used as a reference for quadrivalent nickel.

Mansour, A. N.; McBreen, J.; Melendres, C. A.

1997-03-01

386

Diamond sensors and polycapillary lenses for X-ray absorption spectroscopy  

SciTech Connect

Diamond sensors are evaluated as incident beam monitors for X-ray absorption spectroscopy experiments. These single crystal devices pose a challenge for an energy-scanning experiment using hard X-rays due to the effect of diffraction from the crystalline sensor at energies which meet the Bragg condition. This problem is eliminated by combination with polycapillary lenses. The convergence angle of the beam exiting the lens is large compared to rocking curve widths of the diamond. A ray exiting one capillary from the lens meets the Bragg condition for any reflection at a different energy from the rays exiting adjacent capillaries. This serves to broaden each diffraction peak over a wide energy range, allowing linear measurement of incident intensity over the range of the energy scan. Extended X-ray absorption fine structure data are measured with a combination of a polycapillary lens and a diamond incident beam monitor. These data are of comparable quality to data measured without a lens and with an ionization chamber monitoring the incident beam intensity.

Ravel, B. [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States)] [National Institute of Standards and Technology, Gaithersburg, Maryland 20899 (United States); Attenkofer, K. [Photon Sciences Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)] [Photon Sciences Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States); Bohon, J. [Center for Synchrotron Biosciences, Case Western Reserve University, Cleveland, Ohio 44106 (United States)] [Center for Synchrotron Biosciences, Case Western Reserve University, Cleveland, Ohio 44106 (United States); Muller, E. [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11974-3800 (United States)] [Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11974-3800 (United States); Smedley, J. [Instrumentation Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)] [Instrumentation Division, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

2013-10-15

387

Characterization of the Carancas-Puno meteorite by energy dispersive X-ray fluorescence, X-ray diffractometry and transmission Mössbauer spectroscopy  

NASA Astrophysics Data System (ADS)

We report the results of the study of a meteorite that impacted an inhabited zone on 15 September 2007 in the neighborhood of the town of Carancas, Puno Region, about 1,300 km south of Lima. The analysis carried out by energy dispersive X-ray fluorescence, X-ray diffractometry and transmission Mössbauer spectroscopy (at room temperature and at 4.2 K), reveal the presence in the meteorite sample of magnetic sites assigned to taenite (Fe,Ni) and troilite (Fe,S) phases, and of two paramagnetic doublets assigned to Fe2 + , one associated with olivine and the other to pyroxene. In accord with these results, this meteorite is classified as a type IV chondrite meteorite.

Cerón Loayza, María L.; Bravo Cabrejos, Jorge A.

2011-11-01

388

L-Edge X-ray Absorption Spectroscopy of Dilute Systems Relevant to Metalloproteins Using an X-ray Free-Electron Laser  

PubMed Central

L-edge spectroscopy of 3d transition metals provides important electronic structure information and has been used in many fields. However, the use of this method for studying dilute aqueous systems, such as metalloenzymes, has not been prevalent because of severe radiation damage and the lack of suitable detection systems. Here we present spectra from a dilute Mn aqueous solution using a high-transmission zone-plate spectrometer at the Linac Coherent Light Source (LCLS). The spectrometer has been optimized for discriminating the Mn L-edge signal from the overwhelming O K-edge background that arises from water and protein itself, and the ultrashort LCLS X-ray pulses can outrun X-ray induced damage. We show that the deviations of the partial-fluorescence yield-detected spectra from the true absorption can be well modeled using the state-dependence of the fluorescence yield, and discuss implications for the application of our concept to biological samples.

Mitzner, Rolf; Rehanek, Jens; Kern, Jan; Gul, Sheraz; Hattne, Johan; Taguchi, Taketo; Alonso-Mori, Roberto; Tran, Rosalie; Weniger, Christian; Schroder, Henning; Quevedo, Wilson; Laksmono, Hartawan; Sierra, Raymond G.; Han, Guangye; Lassalle-Kaiser, Benedikt; Koroidov, Sergey; Kubicek, Katharina; Schreck, Simon; Kunnus, Kristjan; Brzhezinskaya, Maria; Firsov, Alexander; Minitti, Michael P.; Turner, Joshua J.; Moeller, Stefan; Sauter, Nicholas K.; Bogan, Michael J.; Nordlund, Dennis; Schlotter, William F.; Messinger, Johannes; Borovik, Andrew; Techert, Simone; de Groot, Frank M. F.; Fohlisch, Alexander; Erko, Alexei; Bergmann, Uwe; Yachandra, Vittal K.; Wernet, Philippe; Yano, Junko

2013-01-01

389

Scanning transmission X-ray microscopy, X-ray photoelectron spectroscopy, and cyclic voltammetry study on the enhanced visible photocatalytic mechanism of carbon-TiO2 nanohybrids  

NASA Astrophysics Data System (ADS)

Carbon-TiO2 nanohybrids (CTs, 5-10 nm TiO2 nanocrystals evenly dispersed on carbon film) have been successfully prepared via a mild, one-step hydrothermal approach. The interactions and electronic structures of carbon and TiO2 nanoparticles and the enhanced visible photocatalytic mechanism were investigated by scanning transmission X-ray microscopy, X-ray photoelectron spectroscopy and cyclic voltammetry in detail. Meanwhile, it was demonstrated that the as-obtained CTs had a large BET specific surface area of 304.6 m2/g and showed excellent photocatalytic abilities towards organic (Rhodamine B, benzene) and inorganic pollutant (K2Cr2O7) degradation in visible light. This work provided a new approach for the high performance catalyst design towards new energy sources and environmental issues.

Ming, Hai; Zhang, Hengchao; Ma, Zheng; Huang, Hui; Lian, Suoyuan; Wei, Ying; Liu, Yang; Kang, Zhenhui

2012-02-01

390

Characterization of Mo additions in iron-based Fischer Tropsch catalysts using X-ray absorption spectroscopy and X-ray diffraction  

NASA Astrophysics Data System (ADS)

An iron-based Fischer-Tropsch catalyst with a low concentration of molybdenum (90Fe/10Mo/5Cu/17Si) used as a promoter was characterized by X-ray absorption spectroscopy (XAS) and X-ray diffractometry (XRD). The catalyst was prepared using coprecipitation, pretreated in CO, then one sample passivated and one calcined. The XRD data show that after CO pretreatment the calcined and passivated catalysts are almost amorphous with respect to Fe 2O 3 with nanoparticle size of 10 and 100 Å for Fe 3C (only present in the passivated sample). Least squares fitting of the XANES region show that the calcined and passivated samples were similar in the bulk and surface structures, with the calcined samples completely oxidized. As expected, K and L III edges Mo-XANES shows only small molybdenum carbide formation compared to iron carbide.

Campos, A.; Spivey, J. J.; Roy, A.; Lohitharn, N.; Goodwin, J.; Lotero, E.; Lamb, H.

2007-11-01

391

Modular instrument mounting system for variable environment in operando X-ray experiments  

NASA Astrophysics Data System (ADS)

In the growing field of in operando and in situ X-ray experiments, there exists a large disparity in the types of environments and equipment to control them. This situation makes it challenging to conduct multiple experiments with a single mechanical interface to the diffractometer. Here, we describe the design and implementation of a modular instrument mounting system that can be installed on a standard six-circle diffractometer (e.g., 5021 Huber GmbH). This new system allows for the rapid changeover of different chambers and sample heaters and permits accurate sample positioning (x, y, z, and azimuthal rotation) without rigid coupling to the chamber body. Isolation of the sample motion from the chamber enclosure is accomplished through a combination of custom rotary seals and bellows. Control of the pressure and temperature has been demonstrated in the ranges of 10-6-103 Torr and 25°C-900°C, respectively. We have utilized the system with several different modular instruments. As an example, we provide in situ sputtering results, where the growth dynamics of epitaxial LaGaO3 thin films on (001) SrTiO3 substrates were investigated.

Folkman, C. M.; Highland, M. J.; Perret, E.; Kim, S. K.; Fister, T. T.; Zhou, H.; Baldo, P. M.; Seifert, S.; Eastman, J. A.; Fuoss, P. H.; Fong, D. D.

2013-02-01

392

Modular instrument mounting system for variable environment in operando X-ray experiments  

SciTech Connect

In the growing field of in operando and in situ X-ray experiments, there exists a large disparity in the types of environments and equipment to control them. This situation makes it challenging to conduct multiple experiments with a single mechanical interface to the diffractometer. Here, we describe the design and implementation of a modular instrument mounting system that can be installed on a standard six-circle diffractometer (e.g., 5021 Huber GmbH). This new system allows for the rapid changeover of different chambers and sample heaters and permits accurate sample positioning (x, y, z, and azimuthal rotation) without rigid coupling to the chamber body. Isolation of the sample motion from the chamber enclosure is accomplished through a combination of custom rotary seals and bellows. Control of the pressure and temperature has been demonstrated in the ranges of 10{sup -6}-10{sup 3} Torr and 25 Degree-Sign C-900 Degree-Sign C, respectively. We have utilized the system with several different modular instruments. As an example, we provide in situ sputtering results, where the growth dynamics of epitaxial LaGaO{sub 3} thin films on (001) SrTiO{sub 3} substrates were investigated.

Folkman, C. M.; Highland, M. J.; Perret, E.; Kim, S. K.; Baldo, P. M.; Eastman, J. A.; Fuoss, P. H.; Fong, D. D. [Materials Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Fister, T. T. [Chemical Sciences and Engineering, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Zhou, H.; Seifert, S. [X-ray Science Division, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

2013-02-15

393

Modular instrument mounting system for variable environment in operando X-ray experiments.  

PubMed

In the growing field of in operando and in situ X-ray experiments, there exists a large disparity in the types of environments and equipment to control them. This situation makes it challenging to conduct multiple experiments with a single mechanical interface to the diffractometer. Here, we describe the design and implementation of a modular instrument mounting system that can be installed on a standard six-circle diffractometer (e.g., 5021 Huber GmbH). This new system allows for the rapid changeover of different chambers and sample heaters and permits accurate sample positioning (x, y, z, and azimuthal rotation) without rigid coupling to the chamber body. Isolation of the sample motion from the chamber enclosure is accomplished through a combination of custom rotary seals and bellows. Control of the pressure and temperature has been demonstrated in the ranges of 10(-6)-10(3) Torr and 25°C-900°C, respectively. We have utilized the system with several different modular instruments. As an example, we provide in situ sputtering results, where the growth dynamics of epitaxial LaGaO3 thin films on (001) SrTiO3 substrates were investigated. PMID:23464255

Folkman, C M; Highland, M J; Perret, E; Kim, S K; Fister, T T; Zhou, H; Baldo, P M; Seifert, S; Eastman, J A; Fuoss, P H; Fong, D D

2013-02-01

394

Atmospheric Electron-induced X-Ray Spectrometer (AEXS) Instrument Development  

NASA Technical Reports Server (NTRS)

Introduction: This paper describes the progress in data acquisition and establishing the observational capability of the AEXS instrument. The AEXS is a miniature instrument[1-4] based on the excitation of characteristic X-Ray Fluorescence (XRF) and luminescence spectra using a focused electron beam which enables nondestructive evaluation of sample surfaces in planetary ambient atmospheres. In situ operation is obtained through the use of a thin electron transmissive membrane to isolate the vacuum of the AEXS source from the outside ambient atmosphere. Thus eliminating the need for a vacuum pumped sample chamber as is common in all laboratory SEM s. The transmitted electrons impinge on the sample exciting XRF spectra from the irradiated spot on in-situ or collected samples with sub-mm to cm-scale spatial resolution at Mars atmospheric pressure. The AEXS system (Fig 1) consists of a high-energy (>10keV) electron gun encapsulated by the isolation membrane, an XRF detection and analyzer system, and a high voltage power supply. The XRF data are analyzed to determine the elemental abundance for the irradiated spots. The approach to demonstrating a proof of concept of the AEXS has been through 1) demonstrating the viability of microfabricated membranes, 2) assembling AEXS setups with increasingly integrated functional components, and 3) simulating the AEXS observational capabilities. The development of the instrument is described in detail in the poster paper[4] at this conference. This paper focuses on describing the progress of the AEXS instrument to acquire XRF data and using commercially available software to analyze the data streams and determine the accuracy, precision and resolution of the analysis compared to the certified elemental abundance.

Urgiles, E.; Wilcox, J. Z.; Toda, R.; Crisp, J.; George, T.

2005-01-01

395

WR 138: new results from X-ray and optical spectroscopy  

NASA Astrophysics Data System (ADS)

Context. Massive-binary evolution models predict that some systems will go through an evolutionary phase where the original primary has become a supernova and left a compact object behind that then orbits a Wolf-Rayet (WR) star. WR 138 is an X-ray bright WR star that has been described as a triple system, including a compact companion in a short-period orbit. Aims: Our goal is to search for spectroscopic evidence of a compact companion around WR 138. Methods: We used optical and X-ray spectra to search for signatures of a compact companion, which can be revealed by systematic variations in WR optical spectral lines induced by orbital motion of the compact companion or by hard, luminous X-rays from accretion onto this companion. Results: The optical spectra display emission-line profile variations that are most probably caused by clumps inside the stellar winds. The radial velocities do not vary on a short time-scale compatible with the suggested orbital period of a putative compact companion. The X-ray spectra are found to be normal for a WN5-6+OB system with no indication of accretion by a compact companion. Conclusions: There is no evidence for the presence of a compact companion, and we therefore conclude that WR 138 is a normal long-period (P ~ 1521 d) eccentric WR+OB system. Based on observations collected at the Observatoire de Haute-Provence (France), the San Pedro Mártir observatory (Mexico), and with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and the USA (NASA).Tables 2-5 are available in electronic form at http://www.aanda.org

Palate, M.; Rauw, G.; De Becker, M.; Nazé, Y.; Eenens, P.

2013-12-01

396

Study of a chemically amplified resist for X-ray lithography by Fourier transform infrared spectroscopy.  

PubMed

Future applications of microelectromechanical systems (MEMS) require lithographic performance of very high aspect ratio. Chemically amplified resists (CARs) such as the negative tone commercial SU-8 provide critical advantages in sensitivity, resolution, and process efficiency in deep ultraviolet, electron-beam, and X-ray lithographies (XRLs), which result in a very high aspect ratio. In this investigation, an SU-8 resist was characterized and optimized for X-ray lithographic applications by studying the cross-linking process of the resist under different conditions of resist thickness and X-ray exposure dose. The exposure dose of soft X-ray (SXR) irradiation at the average weighted wavelength of 1.20 nm from a plasma focus device ranges from 100 to 1600 mJ/cm(2) on the resist surface. Resist thickness varies from 3.5 to 15 mum. The cross-linking process of the resist during post-exposure bake (PEB) was accurately monitored using Fourier transform infrared (FT-IR) spectroscopy. The infrared absorption peaks at 862, 914, 972, and 1128 cm(-1) in the spectrum of the SU-8 resist were found to be useful indicators for the completion of cross-linking in the resist. Results of the experiments showed that the cross-linking of SU-8 was optimized at the exposure dose of 800 mJ/cm(2) for resist thicknesses of 3.5, 9.5, and 15 microm. PEB temperature was set at 95 degrees C and time at 3 min. The resist thickness was measured using interference patterns in the FT-IR spectra of the resist. Test structures with an aspect ratio 3:1 on 10 microm thick SU-8 resist film were obtained using scanning electron microscopy (SEM). PMID:18070406

Tan, T L; Wong, D; Lee, P; Rawat, R S; Patran, A

2004-11-01

397

Probing Electronic Excitations in Molecules by Coherent Multidimensional UV and X Ray Spectroscopy  

NASA Astrophysics Data System (ADS)

Two-dimensional ultraviolet (2DUV) spectra of protein backbone (far UV) and side chains (near UV) provide new insights into the protein structures, dynamics and functions. Simulated chirality-induced 2DUV spectra reveal characteristic patterns of protein secondary structures and allow monitoring the aggregation mechanism of amyloid fibrils and predicting the aggregation propensity of peptides. Time-domain experiments that employ sequences of attosecond x-ray pulses in order to probe electronic and nuclear dynamics in molecules are made possible by newly developed bright coherent ultrafast sources of soft and hard x-rays. By creating multiple core holes at selected atoms and controlled times it should be possible to study the dynamics and correlations of valence electrons as they respond to these perturbations. The stimulated x-ray Raman spectrum of trans-N-methylacetamide and Cysteine at the Nitrogen, Sulfur and the Oxygen K-edges in response to two soft x-ray pulses is calculated by treating the core excitations at the Hartree--Fock static-exchange level (STEX) level. The signal is interpreted in terms of the dynamics of valence electronic wave packets prepared and detected in the vicinity of (either the nitrogen or the oxygen) atom. The evolving electronic charge density and as electronic coherences are visualized using a basis set of time-dependent natural orbitals. Effects of orbital relaxation upon core excitations are resolved. A two-dimensional extension of the technique that involves a sequence of three resonant Raman pulses will be presented. Extensions to multidimensional spectroscopy with photoelectron detection are proposed.

Mukamel, Shaul

2012-02-01

398

Development of time resolved x-ray spectroscopy in high intensity laser-plasma interactions  

NASA Astrophysics Data System (ADS)

This article discusses the design of a novel time resolved von Hamos Bragg spectrometer to provide spectra in the region around the titanium K-? and He-? lines. The instrument consists of a highly oriented pyrolitic graphite mosaic crystal coupled to a picosecond x-ray streak camera. Measurements of the time dependent behavior from Ti foils illuminated with intense laser pulses can be used to improve the understanding of recombination dynamics, electron transport, and phase transitions in strongly coupled dense plasma. This is important for the modeling of the compression phase in inertial confinement fusion research and the study of astrophysical environments.

Notley, M. M.; Weber, R. L.; Fell, B.; Jeffries, J.; Freeman, R. R.; MacKinnon, A. J.; Dickson, R.; Hey, D.; Khattak, F.; Saiz, E. Garcia; Gregori, G.

2006-10-01

399

X-ray photoelectron spectroscopy investigation of commercial passivated tinplate surface layer  

NASA Astrophysics Data System (ADS)

X-ray photoelectron spectroscopy (XPS) combined with the low energy Ar+ sputtering technique has been used to investigate the chemical compositions and chemical states of elements at different depths of commercial passivated tinplate surface layer. It is found that Cr2O3, SnO, Cr(OH)3, metallic Sn and a small amount of metallic Cr have been mixed in this layer. According to peak fitting and relative sensitivity factor method, the concentrations of elements in various chemical environments on different depth planes of the passivated tinplate surface layer have been obtained.

Chen, Sheng; Xie, Long; Xue, Fei

2013-07-01

400

Composition of RF-sputtered refractory compounds determined by X-ray photoelectron spectroscopy  

NASA Technical Reports Server (NTRS)

RF-sputtered coatings of CrB2, MoSi2, Mo2C, TiC, and MoS2 were examined by X-ray photoelectron spectroscopy (XPS). Data on stoichiometry, impurity content, and chemical bonding were obtained. The influences of sputtering target history, deposition time, RF power level, and substrate bias were studied. Significant deviations from stoichiometry and high oxide levels were related to target outgassing. The effect of substrate bias depended on the particular coating material studied.

Wheeler, D. R.; Brainard, W. A.

1978-01-01

401

Contact-free pyroelectric measurements using x-ray photoelectron spectroscopy  

SciTech Connect

Non-contact pyroelectricity measurements based on x-ray photoelectron spectroscopy (XPS) are presented. Applied to Lithium Tantalate crystals, we demonstrate how the XPS-derived surface potential provides a simple probe of the desired property, free of all top-contact related difficulties. In particular, the increase in Lithium Tantalate spontaneous polarization under cooling, an experimentally challenging feature, is evaluated. We further inspect the roll of surface contaminants and the control over trapped surface charge in the XPS vacuum environment. Our approach can be extended to other non-contact probes, as well as to measuring additional electrical properties, such as piezoelectricity and ferroelectricity.

Ehre, D. [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel)] [Department of Materials and Interfaces, Weizmann Institute of Science, Rehovot 76100 (Israel); Cohen, H. [Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100 (Israel)] [Department of Chemical Research Support, Weizmann Institute of Science, Rehovot 76100 (Israel)

2013-07-29

402

Quantitative analysis of annealed scanning probe tips using energy dispersive x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

A quantitative method to measure the reduction in oxide species on the surface of electrochemically etched tungsten tips during direct current annealing is developed using energy dispersive x-ray spectroscopy. Oxide species are found to decrease with annealing current, with the trend repeatable over many tips and along the length of the tip apex. A linear resistivity approximation finds significant oxide sublimation occurs at 1714 K, but surface melting and tip broadening at 2215 K. This method can be applied to calibrate any similar annealing stage, and to identify the tradeoff regime between required morphological and chemical properties.

Cobley, R. J.; Brown, R. A.; Barnett, C. J.; Maffeis, T. G. G.; Penny, M. W.

2013-01-01

403

X-ray absorption spectroscopy studies of electrochemically deposited thin oxide films.  

SciTech Connect

We have utilized ''in situ'' X-ray Absorption Fine Structure Spectroscopy to investigate the structure and composition of thin oxide films of nickel and iron that have been prepared by electrodeposition on a graphite substrate from aqueous solutions. The films are generally disordered. Structural information has been obtained from the analysis of the data. We also present initial findings on the local structure of heavy metal ions, e.g. Sr and Ce, incorporated into the electrodeposited nickel oxide films. Our results are of importance in a number of technological applications, among them, batteries, fuel cells, electrochromic and ferroelectric materials, corrosion protection, as well as environmental speciation and remediation.

Balasubramanian, M.

1998-06-02

404

Radiation damage studies by x-ray photoelectron spectroscopy. III. Electron irradiated halates and perhalates  

Microsoft Academic Search

X-ray photoelectron spectroscopy (XPS) was employed to identify radiolytic products in NaClO3, LiClO3, LiBrO3, and LiIO4 which were irradiated insitu with 1.4 keV electrons. While LiIO4 was exceedingly resistant to radiation damage, the remaining compounds decomposed readily by an apparent stepwise release of oxygen from the parent oxyanion to form XO?3, XO?2, X? (X=Cl or Br) and O2. Heavy irradiation

T. Sasaki; R. S. Williams; J. S. Wong; D. A. Shirley

1979-01-01

405

Radiation damage studies by x-ray photoelectron spectroscopy. III. Electron irradiated halates and perhalates  

Microsoft Academic Search

X-ray photoelectron spectroscopy (XPS) was employed to identify radiolytic products in NaClO3, LiClO3, LiBrO3, and LiIO4 which were irradiated in situ with 1.4 keV electrons. While LiIO4 was exceedingly resistant to radiation damage, the remaining compounds decomposed readily by an apparent stepwise release of oxygen from the parent oxyanion to form XO-3, XO-2, X- (X=Cl or Br) and O2. Heavy

T. Sasaki; R. S. Williams; J. S. Wong; D. A. Shirley

1979-01-01

406

Characterization of plasma fluorinated zirconia for dental applications by X-ray photoelectron spectroscopy  

Microsoft Academic Search

This paper discusses fluorination of biomedical-grade yttria-stabilized zirconia (YSZ) by sulfur hexafluoride plasma treatment and characterization of near-surface chemistry products by X-ray photoelectron spectroscopy (XPS). Deconvolution of the Zr 3d and Y 3d XPS core level spectra revealed formation of both ZrF4 and YF3. In addition, seven-coordinate ZrO2F5 and\\/or ZrO3F4 phases were deconvolved, retaining similar atomic coordination as the parent

S. D. Wolter; J. R. Piascik; B. R. Stoner

2011-01-01

407

X-ray absorption spectroscopy for the structural investigation of self-assembled-monolayer-directed mineralization.  

PubMed

Self-assembled monolayers (SAMs) of organothiol molecules prepared on noble metal substrates are known to exert considerable influence over biomineral nucleation and growth and, as such, offer model templates for investigation of the processes of directed biomineralization. Identifying the structural evolution of SAM/crystal systems is essential for a more comprehensive understanding of the mechanisms by which organic monolayers mediate mineral growth. X-ray absorption spectroscopy (XAS) provides the attractive ability to study SAM structure at critical stages throughout the processes of crystallization in SAM/mineral systems. Here, we discuss important theoretical and experimental considerations for designing and implementing XAS studies of SAM/mineral systems. PMID:24188767

Lee, Jonathan R I; Bagge-Hansen, Michael; Willey, Trevor M; Meulenberg, Robert W; Nielsen, Michael H; Tran, Ich C; van Buuren, Tony

2013-01-01

408

FPGA-based compression of streaming x-ray photon correlation spectroscopy data  

SciTech Connect

A data acquisition system to perform real-time background subtraction and lower-level-discrimination-based compression of streaming x-ray photon correlation spectroscopy (XPCS) data from a fast charge-coupled device (CCD) area detector has been built and put into service at the Advanced Photon source (APS) at Argonne National Laboratory. A commercial frame grabber with on-board field-programmable gate array (FPGA) was used in the design, and continuously processes 60 frames per second each consisting of 1,024 x 1,024 pixels with up to 64512 photon hits per frame.

Madden, Timothy; Jemian, Peter; Narayanan, Surcsh; Sandy, Alec; Sikorski, Marcin; Sprung, Michael; Weizeorick, John

2011-08-09

409

Enzymatic synthesis of amylose brushes revisited: details from X-ray photoelectron spectroscopy and spectroscopic ellipsometry.  

PubMed

The successful synthesis of amylose brushes via enzymatic "grafting from" polymerization and the detailed characterization of all synthetic steps by X-ray photoelectron spectroscopy (XPS) and spectroscopic ellipsometry measurements are reported. Au and Si surfaces are amino-functionalized with self-assembled monolayers (SAMs) of cystamine and 3-aminopropyldimethyethoxysilane (APDMES), respectively. Maltoheptaose is covalently attached to the amino-functionalized Au and Si surfaces via reductive amination. Amylose brushes are grown from maltoheptaose modified Au and Si surfaces with enzymatic polymerization using potato phosphorylase and Rabbit Muscle phosphorylase, as evidenced by spectroscopic ellipsometry and XPS measurements. PMID:24519786

Mazzocchetti, Laura; Tsoufis, Theodoros; Rudolf, Petra; Loos, Katja

2014-02-01

410

The Chemical Forms of Mercury in Human Hair: A Study using X-ray Absorption Spectroscopy  

PubMed Central

Human hair is frequently used as a bio-indicator of mercury exposure. We have used X-ray absorption spectroscopy to examine the chemical forms of mercury in human hair samples taken from individuals with high fish consumption and concomitant exposure to methylmercury. The mercury is found to be predominantly methylmercury cysteine or closely related species, comprising approximately 80% of the total mercury with the remainder an inorganic thiolate-coordinated mercuric species. No appreciable role was found for selenium in coordinating mercury in hair.

George, Graham N.; Singh, Satya P.; Myers, Gary J.; Watson, Gene E.; Pickering, Ingrid J.

2013-01-01

411

Results and perspectives in hard X-ray photoemission spectroscopy (HAXPES) from solids  

NASA Astrophysics Data System (ADS)

We report on the results obtained during the commissioning phase of the volume photoemission (VOLPE) project, now operational at ESRF. Test experiments were performed on noble metals and highly correlated systems, analyzing photoelectrons with kinetic energies up to 8 keV. They confirmed that hard X-ray photoemission spectroscopy (HAXPES) can achieve bulk sensitivity with high energy resolution (e.g. 70 meV at 6 keV kinetic energy). At these kinetic energies, the surface contribution to the measured spectra is less than 5%.

Panaccione, G.; Cautero, G.; Cautero, M.; Fondacaro, A.; Grioni, M.; Henriquet, C.; Monaco, G.; Mulazzi, M.; Offi, F.; Paolasini, L.; Paolicelli, G.; Pittana, P.; Sacchi, M.; Stefani, G.; Torelli, P.

2006-05-01

412

Band offsets of films grown on Ge substrates by X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The band alignments of high-k Er2O3 films grown on Ge substrates by molecular beam epitaxy are determined by X-ray photoelectron spectroscopy. The valence-band and the conduction-band offsets of Er2O3 to Ge are found to be and , respectively. The energy gap of Er2O3 is as determined by the optical spectrophotometry. From the band offset viewpoint, the above results indicate that Er2O3 could be a promising candidate for high-k gate dielectrics on Ge substrate.

Ji, Ting; Peng, Lining; Fang, Zebo; Cui, Yanxia; Hao, Yuying

2014-06-01

413

Slow dynamics of nanocomposite polymer aerogels as revealed by X-ray photocorrelation spectroscopy (XPCS)  

NASA Astrophysics Data System (ADS)

We report on a novel slow dynamics of polymer xerogels, aerogels, and nanocomposite aerogels with iron oxide nanoparticles, as revealed by X-ray photon correlation spectroscopy. The polymer aerogel and its nanocomposite aerogels, which are porous in nature, exhibit hyper-diffusive dynamics at room temperature. In contrast, non-porous polymer xerogels exhibit an absence of this peculiar dynamics. This slow dynamical process has been assigned to a relaxation of the characteristic porous structure of these materials and not to the presence of nanoparticles.

Hernández, Rebeca; Nogales, Aurora; Sprung, Michael; Mijangos, Carmen; Ezquerra, Tiberio A.

2014-01-01

414

Slow dynamics of nanocomposite polymer aerogels as revealed by X-ray photocorrelation spectroscopy (XPCS).  

PubMed

We report on a novel slow dynamics of polymer xerogels, aerogels, and nanocomposite aerogels with iron oxide nanoparticles, as revealed by X-ray photon correlation spectroscopy. The polymer aerogel and its nanocomposite aerogels, which are porous in nature, exhibit hyper-diffusive dynamics at room temperature. In contrast, non-porous polymer xerogels exhibit an absence of this peculiar dynamics. This slow dynamical process has been assigned to a relaxation of the characteristic porous structure of these materials and not to the presence of nanoparticles. PMID:24437913

Hernández, Rebeca; Nogales, Aurora; Sprung, Michael; Mijangos, Carmen; Ezquerra, Tiberio A

2014-01-14

415

Iron location in O-carboxymethyl chitosans determined by X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Chitosans represent a class of functional natural polymers. Their unique attribute is the capability to bind metal ions into their structure. This property can be exploited in many biomedical applications, but before that, some questions about metal binding mechanism must be answered. O-carboxymethyl chitosans with accumulated Fe atoms were studied by X-ray absorption spectroscopy. It was shown that iron bonding depends on the technological processes used in chitosan production. The applied technology allows for the selective introduction of either oxygen alone or of nitrogen and oxygen into the nearest neighbourhood of Fe. Therefore, it is possible to control the surroundings of a metal atom depending on requirements.

Klepka, Marcin T.; Lawniczak-Jablonska, Krystyna; Wolska, Anna; Slawska-Waniewska, Anna; Rodrigues, Clóvis A.; Lorini, Josiane; Cruz, Karianne Araujo da

2011-01-01

416

X-ray Spectroscopy of E2 and M3 Transitions in Ni-like W  

SciTech Connect

The electric quadrupole (E2) and magnetic octupole (M3) ground state transitions in Ni-like W{sup 46+} have been measured using high-resolution crystal spectroscopy at the Livermore electron beam ion trap facility. The lines fall in the soft x-ray region near 7.93 {angstrom} and were originally observed as an unresolved feature in tokamak plasmas. Using flat ADP and quartz crystals the wavelengths, intensities, and polarizations of the two lines have been measured for various electron beam energies and compared to intensity and polarization calculations performed using the Flexible Atomic Code (FAC).

Clementson, J; Beiersdorfer, P; Gu, M F

2009-11-09

417

X-Ray Absorption Spectroscopy of Cuprous-Thiolate Clusters in Saccharomyces Cerevisiae Metallothionein  

SciTech Connect

Copper (Cu) metallothioneins are cuprous-thiolate proteins that contain multimetallic clusters, and are thought to have dual functions of Cu storage and Cu detoxification. We have used a combination of X-ray absorption spectroscopy (XAS) and density-functional theory (DFT) to investigate the nature of Cu binding to Saccharomyces cerevisiae metallothionein. We found that the XAS of metallothionein prepared, containing a full complement of Cu, was quantitatively consistent with the crystal structure, and that reconstitution of the apo-metallothionein with stoichiometric Cu results in the formation of a tetracopper cluster, indicating cooperative binding of the Cu ions by the metallothionein.

Zhang, L.; Pickering, I.J.; Winge, D.R.; George, G.N.

2009-05-28

418

X-Ray Absorption Spectroscopy as a Probe of Elemental Speciation  

SciTech Connect

An effective bioremediation strategy for metals and metalloids must take the chemical state of the contaminants into account. The oxidation state and local atomic environment of contaminants critically affect such factors as their mobility, reactivity and toxicity, and hence the remediation strategy which might be applied. Since contamination exists in diverse environments, it is very likely that the chemical state of the contaminant will be site specific. X-ray absorption spectroscopy provides a unique tool for determining the chemical form of contaminants in most matrices with minimal pretreatment of the sample.

Pickering, Ingrid

2003-09-25

419

X-ray photoelectron spectroscopy analysis of organic materials irradiated with gas cluster ion beam  

SciTech Connect

Irradiation effect of gas cluster ion beams (GCIB) on organic materials were studied with X-ray photoelectron spectroscopy by comparison to that with Ar-monomer ions. In the case of polyimide, the intensity of both N-C = O and -C-O- bond decreased with 500 eV Ar monomer ion irradiation. On the other hand, there was no significant change in the XPS spectra after Ar-GCIB irradiation. From the size-selected GCIB irradiation study, the damages in polyimide decreased with increasing the cluster size owing to the reduction of energy per atoms.

Nakagiri, Motohiro; Toyoda, Noriaki; Yamada, Isao [Incubation center, Graduate school of engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo, 671-2280 (Japan)

2011-01-07

420

X-ray photoelectron spectroscopy study of polyimide thin films with Ar cluster ion depth profiling  

SciTech Connect

X-ray photoelectron spectroscopy depth profiling of polyimide thin films on silicon substrates using an Ar cluster ion beam results in an extremely low degradation of the polyimide chemistry. In the range from 2.5 to 20 kV, a lower cluster ion energy produces a lower sputter induced damage to the polymer and results in an improved polyimide to silicon interface width. The sputtering rates of the polyimide are found to increase exponentially with an increase in the Ar cluster ion energy.

Miyayama, T.; Sanada, N.; Suzuki, M.; Hammond, J. S.; Si, S.-Q. D.; Takahara, A. [ULVAC-PHI, Inc., 370 Enzo, Chigasaki, Kanagawa 253-8522 (Japan); Physical Electronics, Inc., 18725 Lake Drive East, Chanhassen, Minnesota 55317 (United States); Institute for Materials Chemistry and Engineering, Kyushu University, Motooka, Nishi-ku, Fukuoka 819-0395 (Japan)

2010-03-15

421

High pressure synchrotron x-ray powder diffraction and infrared spectroscopy study on brucite  

Microsoft Academic Search

Synchrotron x-ray powder diffraction and infrared (IR) spectroscopy study of brucite were conducted at ambient temperature up to 31 GPa using a diamond anvil cell (DAC) at beamlines X17C and U2A of Nationl Synchrotron Light Source (NSLS). The starting material has an average chemical composition of (Mg0.907C0.109Si0.027Ca0.027Fe0.004)0.93(OH)2. A 16:3:1 methanol-ethanol-water mixture and KBr were used as respective pressure medium for

M. Ma; W. Liu; Z. Chen; Z. Liu; B. Li

2010-01-01

422

Contact-free pyroelectric measurements using x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Non-contact pyroelectricity measurements based on x-ray photoelectron spectroscopy (XPS) are presented. Applied to Lithium Tantalate crystals, we demonstrate how the XPS-derived surface potential provides a simple probe of the desired property, free of all top-contact related difficulties. In particular, the increase in Lithium Tantalate spontaneous polarization under cooling, an experimentally challenging feature, is evaluated. We further inspect the roll of surface contaminants and the control over trapped surface charge in the XPS vacuum environment. Our approach can be extended to other non-contact probes, as well as to measuring additional electrical properties, such as piezoelectricity and ferroelectricity.

Ehre, D.; Cohen, H.

2013-07-01

423

PLS EPU6 beamline for magnetic spectroscopy with circularly polarized soft X-ray  

NASA Astrophysics Data System (ADS)

A 6-cm-period Elliptically Polarized Undulator (EPU6) beamline is being constructed at the Pohang Light Source (PLS) in Korea optimally designed for magnetic spectroscopy studies of materials in the soft X-ray region. This beamline is designed to cover the photon energy range 80-1800 eV with diverse polarization depending on the gap and phase of EPU6. The EPU6 monochromator is a DRAGON type Spherical Grating Monochromator (SGM) designed to provide maximum transmission and energy resolution at the 2p-absorption edges of transition metals and the 3d-, 4d-absorption edges of rare-earth materials.

Baek, In-Gyu; Kim, Jae-Young; Oh, S.-J.

2001-07-01

424

High-Resolution Spectroscopy with the Chandra X-ray Observatory (APS Colloquium, 2007)  

ScienceCinema

The capabilities of the Chandra X-ray Observatory and XMM-Newton for high-resolution spectroscopy have brought tradition plasma diagnostic techniques to the study of cosmic plasma. Observations have probed nearly every class of astronomical object, from young proto-starts through massive O starts and black hole binaries, supernova remnants, active galactic nuclei, and the intergalactic medium. Many of these sources show remarkable rich spectra that reveal new physical information, such as emission measure distributions, elemental abundances, accretion disk and wind signatures, and time variability. This talk will present an overview of the Chandra instrumentaton and selected examples of spectral observations of astrophysical and cosmological importance.

425

Ge overlayer and surface alloy structures on Pt(100) studied using alkali ion scattering spectroscopy, x-ray photoelectron spectroscopy and x-ray photoelectron diffraction  

NASA Astrophysics Data System (ADS)

We have investigated surface structures formed by deposition of Ge on a Pt(100) substrate by using a multi-technique approach utilizing alkali ion scattering spectroscopy (ALISS), x-ray photoelectron spectroscopy (XPS), and x-ray photoelectron diffraction (XPD). ALISS was used to distinguish Ge overlayers from incorporated alloy layers for the surface structures reported, and to supply structural information about the surface alloy or ‘layer compound’ formed by the deposition of 1.5-ML Ge. A Ge adlayer forms following the deposition of 0.2-ML Ge on Pt(100) and annealing at 600 K. ALISS revealed that Ge adatoms in these overlayers had 1D (incomplete c(2 × 2)) Ge–Ge ordering along [010] and equivalent directions, even though this was not directly apparent in observations using LEED and STM. A c(2 × 2)-Ge overlayer was produced after 0.5 ML-Ge deposition on Pt(100) and annealing at 600 K. Deposition of 1.5-ML Ge on Pt(100) and annealing at 600 K caused extensive Ge interdiffusion into the third (subsurface) layer, while the first and second layers remained as a c(2 × 2) Ge overlayer and (1 × 1) Pt layer, respectively. We propose that the Pt(100) substrate thus is ‘capped’ by an alloy film with the structure of a body-centered tetragonal Pt2Ge layer compound, which is terminated by a pure-Ge layer that is indistinguishable from a c(2 × 2)-Ge adlayer. This explains the apparently ‘strange’ result that even though extensive Ge interdiffusion was occurring deeply into the Pt bulk during annealing at 900 and 1200 K, a Ge overlayer remained on the surface. XPS spectra showed a +0.5 eV binding energy shift of the Ge 3d core level and a small (0–0.1 eV) positive shift of the Pt 5d core level compared to Ge(100) and Pt(100) surfaces for the c(2 × 2)-Ge overlayer. There was no effect on these binding energies upon formation of the Pt2Ge layer compound at the surface, and this indicates similar Ge–Pt interactions in the two cases. Compared to other overlayers of Group-IV atoms on metal surfaces, the Ge overlayer on Pt(100) was extraordinarily stable.

Matsumoto, T.; Ho, C.-S.; Batzill, M.; Roszell, J. P.; Koel, B. E.

2014-04-01

426

Hard X-ray and gamma-ray imaging spectroscopy for the next solar maximum  

NASA Technical Reports Server (NTRS)

The objectives and principles are described of a single spectroscopic imaging package that can provide effective imaging in the hard X- and gamma-ray ranges. Called the High-Energy Solar Physics (HESP) mission instrument for solar investigation, the device is based on rotating modulation collimators with germanium semiconductor spectrometers. The instrument is planned to incorporate thick modulation plates, and the range of coverage is discussed. The optics permit the coverage of high-contrast hard X-ray images from small- and medium-sized flares with large signal-to-noise ratios. The detectors allow angular resolution of less than 1 arcsec, time resolution of less than 1 arcsec, and spectral resolution of about 1 keV. The HESP package is considered an effective and important instrument for investigating the high-energy solar events of the near-term future efficiently.

Hudson, H. S.; Crannell, C. J.; Dennis, B. R.; Spicer, D. S.; Davis, J. M.; Hurford, G. J.; Lin, R. P.

1990-01-01