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1

Solar X-Ray Spectroscopy And Polarimetry By Instrument Ping-M Onboard Interhelioprobe  

NASA Astrophysics Data System (ADS)

The instrument PING-M for X-ray spectroscopy and polarimetry of solar full disk radiation is described. It will be the part of scientific instrument set for the InterHelioProbe space mission. Instrument consists of three detectors: the Soft X-ray detector (SXRD), the Hard X-ray detector (HXRD) and Hard X-ray polarimeter (PING-P). Spectrometer SXRD is based on a relatively novel type of semiconductor detector SDD (Silicon Drift Detector) that will operate in the energy range 1.5-25 keV, which is similar to GOES X-Ray Sensor (XRS) region. Unlike GOES the SXRD is capable to measure the energy of each photon with high resolution (better 200 eV at 5.9 keV) and operate with high count rate. The X-ray spectra of solar flares obtained by the SXRD should show evidence of Fe and Fe/Ni line emission and multi-thermal plasma. HXRD operates in energy range 15-150 keV. Fast nonorganic scintillator (is based on LaBr3(Ce)) with good energy resolution (?12% at 60keV and ?3.5% at 662keV) is used. Apart from measurement of spectra the value of the break energy point that separates the thermal and non-thermal processes in flare would be revealed. In the talk the results of testing of laboratory models are presented. PING-P Hard X-ray polarimeter consists of active scatterer made of three organic p-terphenyl scintillators and six peripheral scattered radiation detectors made of CsI(Tl) scintillators. Effective area of polarimeter is about 5 cm2 in its energy range. Minimal measurable degree of polarization is 0.9 % for 100 sec exposition and X1 solar flare.

Kotov, Yury; Dergachev, Valentin; Kochemasov, Alexey; Yurov, Vitaly; Tyshkevich, V.; Glyanenko, Alexander; Savchenko, Mikhail; Lazutkov, Vadim; Skorodumov, Dmitry; Trofimov, Yury; Zakharov, Mikhail; Rubtsov, Igor; Kruglov, Evgeniy

2

Deconvolving instrumental and intrinsic broadening in core-shell x-ray spectroscopies T. T. Fister,1 G. T. Seidler,1,  

E-print Network

Deconvolving instrumental and intrinsic broadening in core-shell x-ray spectroscopies T. T. Fister-shell spectroscopies. For example, intrinsic broadening occurs in x-ray absorption spectroscopy XAS measure- ments-shell x-ray spectroscopies, the measured spectra are often degraded with respect to the underlying, ideal

Seidler, Gerald T.

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

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

NASA Astrophysics Data System (ADS)

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 Zn1-xCoxO 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; Chou, Hsiung; Tseng, Yuan-Chieh

2013-12-01

5

Nuclear Instruments and Methods in Physics Research A 547 (2005) 2441 X-ray photoelectron spectroscopy and diffraction in the  

E-print Network

or synthetic multilayers to achieve position-sensitive densities of states, compositions, and magnetizations structure; Hard X-rays; Synchrotron radiation 1. Introduction X-ray photoelectron spectroscopy (XPS or ESCA of California Davis; Materials Sciences Division, Lawrence Berkeley National Laboratory, 1 Shields Ave., Davis

Fadley, Charles

6

X-Ray Absorption Spectroscopy of Metallobiomolecules  

E-print Network

9/6/09 1 X-Ray Absorption Spectroscopy of Metallobiomolecules The Outskirts of Structural Biology 6, 09] This is a tutorial about the use of X-ray Absorption Spectroscopy (XAS) in biology, RG; Eisenberger, P; Kincaid, BM "X-ray Absorption Spectroscopy of Biological Molecules" Annu. Rev

Scott, Robert A.

7

X-Ray Absorption Spectroscopy of Metallobiomolecules  

E-print Network

2/9/07 1 X-Ray Absorption Spectroscopy of Metallobiomolecules The Outskirts of Structural Biology 9, 07] This is a tutorial about the use of X-ray Absorption Spectroscopy (XAS) in biology, RG; Eisenberger, P; Kincaid, BM "X-ray Absorption Spectroscopy of Biological Molecules" Annu. Rev

Scott, Robert A.

8

Complex of instrumentation KORTES for the EUV and x-ray imaging and spectroscopy of the solar corona  

NASA Astrophysics Data System (ADS)

We report on the current status of the KORTES project - the first sun-oriented mission for the International Space Station to be launched in 2016-2017. KORTES will comprise several imaging and spectroscopic instruments that will observe solar corona in a number of wavebands, covering EUV and X-Ray ranges. A brief overview of the instrumentation of KORTES, its' layout, technical parameters and scientific objectives is given. An additional attention is given to the design of multilayer optics and filters to be employed in EUV instruments of KORTES.

Shestov, Sergey V.; Ulyanov, Artem S.; Vishnyakov, Eugene A.; Pertsov, Andrei A.; Kuzin, Sergey V.

2014-07-01

9

Nuclear Instruments and Methods in Physics Research A 524 (2004) 287294 Dead time and pileup in pulsed parametric X-ray spectroscopy  

E-print Network

in pulsed parametric X-ray spectroscopy Yaron Danon*, Bryndol Sones, Robert Block Department of Mechanical December 2003 Abstract Spectroscopy of parametric X-rays (PXR) from pulsed electron sources is usually done presents a method that allows correction of dead time losses and pileup in pulsed X-ray spectroscopy

Danon, Yaron

10

Large Area X-ray Spectroscopy Mission  

NASA Technical Reports Server (NTRS)

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

1996-01-01

11

CUBIC: x-ray CCD spectroscopy of the diffuse x-ray background  

NASA Astrophysics Data System (ADS)

The cosmic unresolved background instrument using CCDs (CUBIC) is currently scheduled for launch on the Argentine/US SAC-B satellite late this year. This instrument is designed to perform moderate resolution nondispersive x-ray spectroscopy of the diffuse x-ray background over the band 0.2 - 10.0 keV using state-of-the-art photon-counting CCDs. The instrument is optimized for spectroscopy of diffuse emission with a field of view of 5 degrees by 5 degrees below 1 keV and 10 degrees by 10 degrees above 3 keV. Observations will typically last 1 - 3 days, and will obtain high quality CCD spectra of the diffuse background, nearby superbubbles and supernova remnants, and the brightest x-ray point sources. This paper gives an overview of the instrument design and CCD detectors.

Burrows, David N.; Skinner, Mark A.; Broos, Patrick S.; Catalano, Mark A.; Cawley, Laura J.; Cocklin, Eric J.; Engel, Leland G.; Entingh, Timothy J.; Garmire, Gordon P.; Green, Roland; Janches, Diego; Kelly, Douglas A.; Mendenhall, Jeffrey A.; Nousek, John A.; Lumb, David H.; Holland, Andrew D.; Pool, Peter J.

1995-09-01

12

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

13

Large Area X-Ray Spectroscopy Mission  

NASA Technical Reports Server (NTRS)

The Large Area X-ray Spectroscopy (LAXS) mission concept study continues to evolve strongly following the merging of the LAXS mission with the Next Generation X-ray Observatory (NGXO, PI: Nick White) into the re-named High Throughput X-ray Spectroscopy (HTXS) Mission. HTXS retains key elements of the LAXS proposal, including the use of multiple satellites for risk-reduction and cost savings. A key achievement of the program has been the recommendation by the Structure and Evolution of the Universe (SEUS) (April 1997) for a new start for the HTXS mission in the 2000-2004 timeframe.

Tananbaum, H.

1997-01-01

14

Bent crystal spectrometer for solar X-ray spectroscopy  

NASA Technical Reports Server (NTRS)

A bent crystal spectrometer employs a collimated beam of X-rays incident on the crystal over a range of Bragg angles determined by the orientation and curvature of the crystal surface. It provides continuous and simultaneous coverage of all X-ray wavelengths within its spectral range. In-flight testing for solar X-ray spectroscopy was performed using a small instrument to supplement the wavelength coverage of several scanning spectrometers used to study solar active regions in the 9-24 A range. Later testing included modifications to alleviate problems caused by ultraviolet radiation. Future usage of the device will include studies of time variable emission from solar flares or discrete galactic X-ray sources, and the first major experiment to utilize bent crystal spectrometers will be the Solar Maximum Mission satellite in 1979.

Rapley, C. G.; Culhane, J. L.; Acton, L. W.; Catura, R. C.; Joki, E. G.; Bakke, J. C.

1977-01-01

15

X-ray spectroscopy: Enlightened state  

NASA Astrophysics Data System (ADS)

Determining the sequence of events following photon absorption by a molecule can be a surprisingly challenging task. An innovative use of time-resolved X-ray spectroscopy has revealed an important insight into the ultrafast excited-state dynamics of a well-known inorganic chromophore.

McCusker, James K.

2014-07-01

16

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

NASA Astrophysics Data System (ADS)

We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low power x-ray (bremsstrahlung) tube source, a spherically bent crystal analyzer, and an energy-resolving solid-state detector. This relatively inexpensive, introductory level instrument achieves 1-eV energy resolution for photon energies of ˜5 keV to ˜10 keV while also demonstrating a net efficiency previously seen only in laboratory monochromators having much coarser energy resolution. Despite the use of only a compact, air-cooled 10 W x-ray tube, we find count rates for nonresonant x-ray emission spectroscopy comparable to those achieved at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure, the monochromatized flux is small (due to the use of a low-powered x-ray generator) but still useful for routine transmission-mode studies of concentrated samples. These results indicate that upgrading to a standard commercial high-power line-focused x-ray tube or rotating anode x-ray generator would result in monochromatized fluxes of order 106-107 photons/s with no loss in energy resolution. This work establishes core technical capabilities for a rejuvenation of laboratory-based hard x-ray spectroscopies that could have special relevance for contemporary research on catalytic or electrical energy storage systems using transition-metal, lanthanide, or noble-metal active species.

Seidler, G. T.; Mortensen, D. R.; Remesnik, A. J.; Pacold, J. I.; Ball, N. A.; Barry, N.; Styczinski, M.; Hoidn, O. R.

2014-11-01

17

Quantitation of Auger and X-ray photoelectron spectroscopies  

SciTech Connect

Surface analysis using electron spectroscopies is now a well-established and continuously expanding area. With appropriate data treatment procedures, both Auger electron spectroscopy (AES, not to be confused with atomic expression spectroscopy) and X-ray photoelectron spectroscopy (XPS or ESCA) can routinely supply reliable qualitative and semiquantitative characterization of the near-surface region (top 1-100 /Angstrom/) of most solids. Complex sample matrix and instrumental parameters make quantitation of surface electron spectroscopies a real challenge. Kenneth W. Nebesny, Brian L. Mashloff, and Neal R. Armstrong of the University of Arizona describe approaches that make it possible to obtain reliable compositional information.

Nebesny, K.W.; Maschhoff, B.L.; Armstrong, N.R.

1989-04-01

18

Global spectroscopy and imaging of atmospheric X-ray bremsstrahlung - Instrumentation and initial results from the PEM\\/AXIS instrument aboard the Upper Atmosphere Research Satellite  

Microsoft Academic Search

The Atmospheric X-ray Imaging Spectrometer (PEM\\/AXIS) aboard NASA's Upper Atmosphere Research Satellite provides continuous horizon to horizon images, both day and night, of the 3- to 100-keV X-ray flux emitted from the top of the atmosphere. AXIS achieves a spatial resolution to better than 100 km using a one-dimensional array of 16 passively cooled silicon detectors. The primary purpose of

D. L. Chenette; D. W. Datlowe; W. L. Imhof; T. L. Schumaker; J. D. Tobin

1992-01-01

19

Instrument Development for X-Ray Astronomy  

NASA Technical Reports Server (NTRS)

Current x-ray observatories such as Chandra and XMM-Newton have delivered spectacular results at soft-x-ray energies thanks to their grazing incidence mirrors. To continue these advances necessitates the development of mirrors with even larger collecting areas, yet within manageable weights and budgets, and focal detectors with improved energy resolution. At higher energies where x-ray critical-grazing angles become very small, x-ray optics have typically not been employed and thus this region remains relatively unexplored at high sensitivity levels and fine angular resolutions. This situation is changing with the development of hard-x-ray optics carried aloft by high-altitude balloons, which promise to bring about dramatic advances. This presentation will review developments in all these areas.

Ramsey, Brian; Whitaker, Ann F. (Technical Monitor)

2001-01-01

20

High-resolution X-ray spectroscopy of ? Carinae  

NASA Astrophysics Data System (ADS)

Context: The peculiar hot star ? Car in the open cluster IC 2602 is a blue straggler as well as a single-line binary with a short period (2.2d). Aims: Its high-energy properties are not well known, though X-rays can provide useful constraints on the energetic processes at work in binaries as well as in peculiar, single objects. Methods: We present the analysis of a 50 ks exposure taken with the XMM-Newton observatory. It provides medium as well as high-resolution spectroscopy. Results: Our high-resolution spectroscopy analysis reveals a very soft spectrum with multiple temperature components (1-6 MK) and an X-ray flux slightly below the `canonical' value (log [L_X(0.1{-}10.)/L_BOL]˜-7). The X-ray lines appear surprisingly narrow and unshifted, reminiscent of those of ? Cru and ? Sco. Their relative intensities confirm the anomalous abundances detected in the optical domain (C strongly depleted, N strongly enriched, O slightly depleted). In addition, the X-ray data favor a slight depletion in neon and iron, but they are less conclusive for the magnesium abundance, which may be solar-like. While no significant changes occur during the XMM-Newton observation, variability in the X-ray domain is detected in the long-term range. The formation radius of the X-ray emission is loosely constrained to < 5 R?, which allows for a range of models (wind-shock, corona, magnetic confinement, ...) though not all of them can be reconciled with the softness of the spectrum and the narrowness of the lines. Based on observations collected with XMM-Newton, an ESA Science Mission with instruments and contributions directly funded by ESA Member States and the USA (NASA).

Nazé, Y.; Rauw, G.

2008-11-01

21

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

22

Combined x-ray absorption spectroscopy and x-ray powder diffraction  

Microsoft Academic Search

The complementary nature of x-ray absorption fine structure (XAFS) spectroscopy and x-ray diffraction (XRD) is described. In particular XAFS records the local structure while XRD detects the long-range crystallinity enabling the heterogeneity of materials like single-phase catalysts to be explored. Both measurements can be combined to facilitate novel in situ experiments. We have used a horizontal energy dispersed x-ray beam

Andrew J. Dent; Gareth E. Derbyshire; G. N. Greaves; Christine A. Ramsdale; J. W. Couves; Richard Jones; C. R. Catlow; John M. Thomas

1991-01-01

23

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

24

Constellation-X Spectroscopy X-Ray Telescope Segmented Optic Assembly and Alignment Implementation  

E-print Network

Constellation-X Spectroscopy X-Ray Telescope Segmented Optic Assembly and Alignment Implementation. ABSTRACT The Constellation-X mission will perform X-Ray science with improvements in energy resolution and effective area over its predecessor missions. The primary instrument on each of the four Constellation

25

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

26

New Developments in Femtosecond Soft X-ray Spectroscopy  

NASA Astrophysics Data System (ADS)

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.

2010-06-01

27

CUBIC2: Spectroscopy of the Diffuse X-ray Background  

NASA Astrophysics Data System (ADS)

The CUBIC instrument on the US/Argentine SAC-B satellite was lost due to a Pegasus launch failure in 1996 November. Improved spectroscopy of the diffuse X-ray background is still needed to further our understanding of both cosmic and galactic components. We describe a proposed reflight of CUBIC that can be accomodated within the UNEX program. With new detectors, CUBIC2 will be capable of energy resolution as good as 30 eV at low energies, and will extend the low energy bandpass to below 100 eV. We present simulated spectra and compare them with spectra obtained on sounding rocket flights using similar detectors.

Burrows, D. N.; Nousek, J. A.; Garmire, G. P.

1997-12-01

28

Instrumentation and analytical methods of an x-ray photoelectron spectroscopy-scanning tunneling microscopy surface analysis system for studying nanostructured materials  

NASA Astrophysics Data System (ADS)

The design and performance of an x-ray photoelectron spectroscopy (XPS)-scanning tunneling microscopy (STM) surface analysis system for studying nanostructured materials are described. The analysis system features electron spectroscopy methods (XPS and Auger electron spectroscopy) in addition to a variable temperature STM. With the analytical methods of the system, surface chemical analysis as well as surface morphology down to atomic resolution can be obtained. The system also provides facilities for sample cleaning, annealing, gas dosing, depth profiling, and surface modifications by sputtering and evaporation. Controlled gas exposures from ultrahigh vacuum to atmospheric pressures in the adjustable temperature range of 120-1100K can be carried out in different chambers. A fast entry air lock allows the transfer of samples and STM tips into the system without air exposures. The surface analysis system uses a common sample holder in all five chambers which are independently pumped and separated from each other by gate valves. Thus, it is possible to make all sample preparations and experiments in situ under well-defined conditions as illustrated by the formation and characterization of strained, self-assembled nano-oxides on Cu(100).

Lahtonen, K.; Lampimäki, M.; Jussila, P.; Hirsimäki, M.; Valden, M.

2006-08-01

29

Current Problems in X-Ray Emission Spectroscopy  

NASA Technical Reports Server (NTRS)

Various problems that limit X-ray analysis in the analytical electron microscope are reviewed. Major emphasis is given to the trade-off between minimum mass fraction and spatial resolution. New developments such as high-brightness electron guns, new X-ray spectrometers and clean high-vacuum analysis conditions will lead to major improvements in the accuracy and detectability limits of X-ray emission spectroscopy.

Goldstein, Joseph I.; Williams, David B.; Lyman, Charles E.

1989-01-01

30

Application of Synchrotron X-Ray Microbeam Spectroscopy to the  

E-print Network

Application of Synchrotron X-Ray Microbeam Spectroscopy to the Determination of Metal Distribution-generation synchrotron facilities that produce focused, hard x-ray microbeams ,1 mm in diameter, spatial metal analysis is essential for understanding bioavailability, trophic transfer, and environmental risk. We used synchrotron x

Hopkins, William A.

31

A high-resolution large-acceptance analyzer for X-ray fluorescence and Raman spectroscopy  

SciTech Connect

A newly designed multi-crystal X-ray spectrometer and its applications in the fields of X-ray fluorescence and X-ray Raman spectroscopy are described. The instrument is based on 8 spherically curved Si crystals, each with a 3.5 inch diameter form bent to a radius of 86 cm. The crystals are individually aligned in the Rowland geometry capturing a total solid angle of 0.07 sr. The array is arranged in a way that energy scans can be performed by moving the whole instrument, rather than scanning each crystal by itself. At angles close to back scattering the energy resolution is between 0.3 and 1 eV depending on the beam dimensions at the sample. The instrument is mainly designed for X-ray absorption and fluorescence spectroscopy of transition metals in dilute systems such as metalloproteins. First results of the Mn K{beta} (3p -> 1s) emission in photosystem II are shown. An independent application of the instrument is the technique of X-ray Raman spectroscopy which can address problems similar to those in traditional soft X-ray absorption spectroscopies, and initial results are presented.

Bergmann, Uwe; Cramer, Stephen P.

2001-08-02

32

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

33

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

34

Tokamak Spectroscopy for X-Ray Astronomy  

NASA Technical Reports Server (NTRS)

This paper presents the measured x-ray and Extreme Ultraviolet (XUV) spectra of three astrophysically abundant elements (Fe, Ca and Ne) from three different tokamak plasmas. In every case, each spectrum touches on an issue of atomic physics that is important for simulation codes to be used in the analysis of high spectral resolution data from current and future x-ray telescopes. The utility of the tokamak as a laboratory test bed for astrophysical data is demonstrated. Simple models generated with the HULLAC suite of codes demonstrate how the atomic physics issues studied can affect the interpretation of astrophysical data.

Fournier, Kevin B.; Finkenthal, M.; Pacella, D.; May, M. J.; Soukhanovskii, V.; Mattioli, M.; Leigheb, M.; Rice, J. E.

2000-01-01

35

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

36

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

37

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

38

Soft x-ray absorption spectroscopy measurement methods with using x-ray scattering techniques  

NASA Astrophysics Data System (ADS)

Methodology via x-ray absorption spectroscopy (XAS) has been actively employed for exploring the microscopic aspects of materials. In particular, such method within soft x-ray energy range is very useful for investigating strongly correlated systems, such as high TC superconductor, and multiferroic, including heterostructures. While XAS approach on such materials has been used, however we sometimes confront a few of experimental difficulties; electron motion distortion under external fields, charging effect, and saturation effect. In this presentation, we introduce an alternative approach for overcoming the difficulties in conventional XAS measurement, which uses soft x-ray scattering techniques, i.e., reflection and diffraction. Due to photon-in and photon-out nature, probing depth becomes longer and possible to reduce several problems in conventional total electron yield method. The results of demonstrations on simple monoxide CoO and multiferroic Y-type hexaferrites will be given.

Jang, H.; Lee, J.-S.; Noh, W.-S.; Ko, K.-T.; Lee, K.-B.; Park, B.-G.; Kim, J.-Y.; Chun, S. H.; Kim, K. H.; Park, J.-H.

2012-02-01

39

Soft-x-ray spectroscopy study of nanoscale materials  

SciTech Connect

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, J.-H.

2005-07-30

40

X-ray diffraction assisted spectroscopy of Rydberg states  

SciTech Connect

X-ray diffraction combined with conventional spectroscopy could provide a powerful means to characterize electronically excited atoms and molecules. We demonstrate theoretically how x-ray diffraction from laser excited atoms can be used to determine electronic structure, including angular momentum composition, principal quantum numbers, and channel populations. A theoretical formalism appropriate for highly excited atoms, and easily extended to molecules, is presented together with numerical results for Xe and H atoms.

Kirrander, Adam [ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138 (United States)

2012-10-21

41

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

42

Chemical Shifts in X-ray and Photo-Electron Spectroscopy: A Historical review  

E-print Network

Chemical Shifts in X-ray and Photo-Electron Spectroscopy: A Historical review Ingvar Lindgren 1 Introduction 2 2 Chemical shift in X-ray spectroscopy 2 2.1 Discovery of the chemical shift in X-ray spectroscopy . . . . . . . . . . . . . 3 2.2 Interpretation of the chemical shift in X-ray spectroscopy

Lindgren, Ingvar

43

Combining scanning probe microscopy and x-ray spectroscopy  

PubMed Central

A new versatile tool, combining Shear Force Microscopy and X-Ray Spectroscopy was designed and constructed to obtain simultaneously surface topography and chemical mapping. Using a sharp optical fiber as microscope probe, it is possible to collect locally the visible luminescence of the sample. Results of tests on ZnO and on ZnWO4 thin layers are in perfect agreement with that obtained with other conventional techniques. Twin images obtained by simultaneous acquisition in near field of surface topography and of local visible light emitted by the sample under X-Ray irradiation in synchrotron environment are shown. Replacing the optical fibre by an X-ray capillary, it is possible to collect local X-ray fluorescence of the sample. Preliminary results on Co-Ti sample analysis are presented. PMID:21711848

2011-01-01

44

Effect of X-ray flux on polytetrafluoroethylene in X-ray photoelectron spectroscopy  

NASA Technical Reports Server (NTRS)

The effect of the X-ray flux in X-ray photoelectron spectroscopy (STAT) on the constitution of the polytetrafluoroethylene (PTFE) surface has been examined. The radiation dose rate for our specimen was about 10 to the 7th rad/s. The structure, magnitude and binding energy of the C(1s) and F(1s) features of the XPS spectrum and the mass spectrum of gaseous species evolved during irradiation are observed. The strong time dependence of these signals over a period of several hours indicated that the surface constitution of PTFE is greatly affected by this level of radiation dose. The results are consistent with the development of a heavily cross-linked or branched structure in the PTFE surface region and the evolution of short chain fragments into the gas phase.

Wheeler, D. R.; Pepper, S. V.

1982-01-01

45

Indirectly illuminated X-ray area detector for X-ray photon correlation spectroscopy.  

PubMed

An indirectly illuminated X-ray area detector is employed for X-ray photon correlation spectroscopy (XPCS). The detector consists of a phosphor screen, an image intensifier (microchannel plate), a coupling lens and either a CCD or CMOS image sensor. By changing the gain of the image intensifier, both photon-counting and integrating measurements can be performed. Speckle patterns with a high signal-to-noise ratio can be observed in a single shot in the integrating mode, while XPCS measurement can be performed with much fewer photons in the photon-counting mode. By switching the image sensor, various combinations of frame rate, dynamic range and active area can be obtained. By virtue of these characteristics, this detector can be used for XPCS measurements of various types of samples that show slow or fast dynamics, a high or low scattering intensity, and a wide or narrow range of scattering angles. PMID:20975218

Shinohara, Yuya; Imai, Ryo; Kishimoto, Hiroyuki; Yagi, Naoto; Amemiya, Yoshiyuki

2010-11-01

46

Transient x-ray absorption spectroscopy of hydrated halogen atom  

E-print Network

Time-resolved x-ray absorption spectroscopy has been used to observe the transient species generated by one-photon detachment of an electron from aqueous bromide. The K-edge spectrum of the short-lived Br(0) atom exhibits a resonant 1s-4p transition...

Elles, Christopher G.; Shkrob, Ilya A.; Crowell, Robert A.; Arms, Dohn A.; Landahl, Eric C.

2008-02-11

47

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.

48

Single atom identification by energy dispersive x-ray spectroscopy  

SciTech Connect

Using aberration-corrected scanning transmission electron microscope and energy dispersive x-ray spectroscopy, single, isolated impurity atoms of silicon and platinum in monolayer and multilayer graphene are identified. Simultaneously acquired electron energy loss spectra confirm the elemental identification. Contamination difficulties are overcome by employing near-UHV sample conditions. Signal intensities agree within a factor of two with standardless estimates.

Lovejoy, T. C.; Dellby, N.; Krivanek, O. L. [Nion, 1102 8th St., Kirkland, Washington 98033 (United States); Ramasse, Q. M. [SuperSTEM Laboratory, STFC Daresbury, Keckwick Lane, Daresbury WA4 4AD (United Kingdom); Falke, M.; Kaeppel, A.; Terborg, R. [Bruker Nano GmbH, Schwarzschildstr. 12, 12489 Berlin (Germany); Zan, R. [School of Physics and Astronomy, University of Manchester, Manchester M13 9PL (United Kingdom)

2012-04-09

49

Instrumentation and data analysis for hard X ray astronomy  

Microsoft Academic Search

The current status of hard x ray astronomy is reviewed. The applicability of various hard x ray detectors in such new telescopes are discussed and the current status of hard x ray telescope design is reviewed. Background production mechanisms in hard x ray telescopes are discussed and some techniques for background reduction are also discussed. A simple method for estimating

Shuang Nan Zhang

1989-01-01

50

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

Code of Federal Regulations, 2012 CFR

...2012-07-01 2012-07-01 false X-ray, major instrument, fluoroscope, or surgical...and Inmate Work Areas § 552.13 X-ray, major instrument, fluoroscope, or surgical...institution physician may authorize use of an X-ray for medical reasons and only with the...

2012-07-01

51

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, or surgical...and Inmate Work Areas § 552.13 X-ray, major instrument, fluoroscope, or surgical...institution physician may authorize use of an X-ray for medical reasons and only with the...

2010-07-01

52

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

Code of Federal Regulations, 2013 CFR

...2013-07-01 2013-07-01 false X-ray, major instrument, fluoroscope, or surgical...and Inmate Work Areas § 552.13 X-ray, major instrument, fluoroscope, or surgical...institution physician may authorize use of an X-ray for medical reasons and only with the...

2013-07-01

53

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

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false X-ray, major instrument, fluoroscope, or surgical...and Inmate Work Areas § 552.13 X-ray, major instrument, fluoroscope, or surgical...institution physician may authorize use of an X-ray for medical reasons and only with the...

2011-07-01

54

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

...2014-07-01 2014-07-01 false X-ray, major instrument, fluoroscope, or surgical...and Inmate Work Areas § 552.13 X-ray, major instrument, fluoroscope, or surgical...institution physician may authorize use of an X-ray for medical reasons and only with the...

2014-07-01

55

Resonant Soft-x-ray Emission Spectroscopy of Liquids  

NASA Astrophysics Data System (ADS)

We present now a possible way to carry out soft-x-ray fluorescence spectroscopy of liquids. The liquid cell has a window to attain compatibility with UHV conditions of the spectrometer and beamline, The synchrotron radiation enters the liquid cell through a 100 nm-thick silicon nitride window and the emitted x-rays exit through the same window. This allows in particular liquid-solid interfaces to be studied. Such a liquid cell has been used to study the electronic structure of a variety of systems ranging from water solutions of inorganic salts and inertial drugs to nano materials and actinide compounds in their wet conditions.

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

2004-05-01

56

Improved x-ray spectroscopy with room temperature CZT detectors.  

PubMed

Compact, room temperature x-ray spectroscopy detectors are of interest in many areas including diagnostic x-ray imaging, radiation protection and dosimetry. Room temperature cadmium zinc telluride (CZT) semiconductor detectors are promising candidates for these applications. One of the major problems for CZT detectors is low-energy tailing of the energy spectrum due to hole trapping. Spectral post-correction methods to correct the tailing effect do not work well for a number of reasons; thus it is advisable to eliminate the hole trapping effect in CZT using physical methods rather than correcting an already deteriorated energy spectrum. One method is using a CZT detector with an electrode configuration which modifies the electric field in the CZT volume to decrease low-energy tailing. Another method is to irradiate the CZT surface at a tilted angle, which modifies depth of interaction to decrease low-energy tailing. Neither method alone, however, eliminates the tailing effect. In this work, we have investigated the combination of modified electric field and tilted angle irradiation in a single detector to further decrease spectral tailing. A planar CZT detector with 10 × 10 × 3 mm³ size and CZT detector with 5 × 5 × 5 mm³ size and cap-shaped electrode were used in this study. The cap-shaped electrode (referred to as CAPture technology) modifies the electric field distribution in the CZT volume and decreases the spectral tailing effect. The detectors were investigated at 90° (normal) and 30° (tilted angle) irradiation modes. Two isotope sources with 59.6 and 122 keV photon energies were used for gamma-ray spectroscopy experiments. X-ray spectroscopy was performed using collimated beams at 60, 80 and 120 kVp tube voltages, in both normal and tilted angle irradiation. Measured x-ray spectra were corrected for K x-ray escape fractions that were calculated using Monte Carlo methods. The x-ray spectra measured with tilted angle CAPture detector at 60, 80 and 120 kVp tube voltages were compared to corresponding theoretical spectra. The low-energy tailing was nearly completely eliminated from 59.6 and 122 keV isotope spectra, and 60, 80 and 120 kVp x-ray spectra, when CAPture detector was used with 30° tilted angle irradiation. It is concluded that using a CZT detector with modified electric field in tilted angle configuration resolves problem of the tailing effect in CZT detectors, opening promising possibilities in gamma-ray and x-ray spectroscopy applications. PMID:21841213

Fritz, Shannon G; Shikhaliev, Polad M; Matthews, Kenneth L

2011-09-01

57

Proton induced quasi-monochromatic x-ray beams for soft x-ray spectroscopy studies and selective x-ray fluorescence analysis  

SciTech Connect

We present the analytical features and performance of an x-ray spectroscopy end station of moderate energy resolution operating with proton-induced quasi-monochromatic x-ray beams. The apparatus was designed, installed and operated at the 5.5 MV Tandem VdG Accelerator Laboratory of the Institute of Nuclear Physics, N.C.S.R. 'Demokritos,' Athens. The setup includes a two-level ultrahigh vacuum chamber that hosts in the lower level up to six primary targets in a rotatable holder; there, the irradiation of pure element materials-used as primary targets-with few-MeV high current ({approx}{mu}A) proton beams produces intense quasi-monochromatic x-ray beams of selectable energy. In the chamber's upper level, a six-position rotatable sample holder hosts the targets considered for x-ray spectroscopy studies. The proton-induced x-ray beam, after proper collimation, is guided to the sample position whereas various filters can be also inserted along the beam's path to eliminate the backscattered protons or/and to absorb selectively components of the x-ray beam. The apparatus incorporates an ultrathin window Si(Li) spectrometer (FWHM 136 eV at 5.89 keV) coupled with low-noise electronics capable of efficiently detecting photons down to carbon K{alpha}. Exemplary soft x-ray spectroscopy studies and results of selective x-ray fluorescence analysis are presented.

Sokaras, D. [Institute of Nuclear Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Zarkadas, Ch. [PANalytical B.V., 7600 AA Almelo (Netherlands); Fliegauf, R.; Beckhoff, B. [Physikalisch-Technische Bundesanstalt, Abbestrasse 2-12, 10587 Berlin (Germany); Karydas, A. G. [Institute of Nuclear Physics, N.C.S.R. Demokritos, Aghia Paraskevi, 15310 Athens (Greece); Nuclear Spectrometry and Applications Laboratory, IAEA Laboratories, A-2444 Seibersdorf (Austria)

2012-12-15

58

Nuclear Instruments and Methods in Physics Research A 560 (2006) 589597 X-ray imaging with parametric X-rays (PXR) from a  

E-print Network

Nuclear Instruments and Methods in Physics Research A 560 (2006) 589­597 X-ray imaging with parametric X-rays (PXR) from a lithium fluoride (LiF) crystal B. Sones, Y. Danon�, R.C. Block Gaerttner LINAC January 2006 Available online 13 February 2006 Abstract X-ray imaging produced by parametric X-rays (PXR

Danon, Yaron

59

Tracking of azobenzene isomerization by X-ray emission spectroscopy.  

PubMed

Cis-trans isomerizations are among the fundamental processes in photochemistry. In azobenzene or its derivatives this dynamics is, due to its reversibility, one of the reactions widely used in photostimulation of molecular motors or in molecular electronics. Though intensively investigated in the optical regime, no detailed study exists in the X-ray regime so far. Because the X-ray emission spectroscopy echoes the electronic structure sensitive to the geometry, this theoretical report based on the density functional theory and its time-dependent version presents different nitrogen K-edge X-ray emission spectra for cis and trans isomers with close interrelation to their electron configuration. Considering the spectrum along the isomerization path, these structural signatures can be utilized to probe the isomerization dynamics in the excited molecule. The scheme can further be generalized to the element specific photoreactions. PMID:25134009

Ebadi, H

2014-09-11

60

Simultaneous surface plasmon resonance and x-ray absorption spectroscopy  

SciTech Connect

We present an experimental setup for the simultaneous measurement of surface plasmon resonance (SPR) and x-ray absorption spectroscopy (XAS) on metallic thin films at a synchrotron beamline. The system allows measuring in situ and in real time the effect of x-ray irradiation on the SPR curves to explore the interaction of x-rays with matter. It is also possible to record XAS spectra while exciting SPR in order to study changes in the films induced by the excitation of surface plasmons. Combined experiments recording simultaneously SPR and XAS curves while scanning different parameters can be also carried out. The relative variations in the SPR and XAS spectra that can be detected with this setup range from 10{sup -3} to 10{sup -5}, depending on the particular experiment.

Serrano, A. [Instituto de Ceramica y Vidrio (ICV-CSIC), Cantoblanco, 28049 Madrid (Spain); Departamento de Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Rodriguez de la Fuente, O. [Departamento de Fisica de Materiales, Universidad Complutense de Madrid, 28040 Madrid (Spain); Collado, V.; Rubio-Zuazo, J.; Castro, G. R. [SpLine, Spanish CRG Beamline at the ESRF, F-38043 Grenoble, Cedex 09, France and Instituto de Ciencia de Materiales de Madrid, (ICMM-CSIC), Cantoblanco, 28049 Madrid (Spain); Monton, C. [Department of Physics and Center for Advanced Nanoscience, University of California San Diego, La Jolla, California 92093 (United States); Garcia, M. A. [Instituto de Ceramica y Vidrio (ICV-CSIC), Cantoblanco, 28049 Madrid (Spain); IMDEA Nanociencia, Cantoblanco, 28049 Madrid (Spain)

2012-08-15

61

An upgraded x-ray spectroscopy diagnostic on MST.  

PubMed

An upgraded x-ray spectroscopy diagnostic is used to measure the distribution of fast electrons in MST and to determine Z(eff) and the particle diffusion coefficient D(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(eff) and D(r). PMID:21034007

Clayton, D J; Almagri, A F; Burke, D R; Forest, C B; Goetz, J A; Kaufman, M C; O'Connell, R

2010-10-01

62

High-resolution kaonic-atom x-ray spectroscopy with transition-edge-sensor microcalorimeters  

E-print Network

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.

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

2014-02-19

63

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. 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.

2014-09-01

64

fSurface analysis with XRay Photoelectron SpectroscopyX Ray Photoelectron Spectroscopy  

E-print Network

.com) #12;L1 or 2s 2p K or 1s photoelectron X-Rays K or 1s Ek=Eb-h ­ spek b spe Kinetic energy Binding of energies #12;Detector V Avalanche effect: gains of 107-108 electrons #12;XPS spectrum of chromate coatingfSurface analysis with XRay Photoelectron SpectroscopyX Ray Photoelectron Spectroscopy Marta

Shoubridge, Eric

65

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

66

X-ray photon correlation spectroscopy in microfluidic ssytems  

Microsoft Academic Search

We present a new experimental method that combines X-ray photon Correlation Spectroscopy (XPCS) and microfluidics and allows the direct measurement of the mesoscale dynamics of various soft matter systems (e.g. colloids, polymers, biological molecules like proteins, RNA, etc.) under flow conditions. Such a setup reduces the risk of beam damage and also allows time-resolved studies of various processes taking place

Andrei Fluerasu

2007-01-01

67

Effect of x-ray beamline optics on x-ray photon correlation spectroscopy experiments.  

SciTech Connect

We have evaluated the applicability of vertically-focusing kinoform lenses for tailoring the vertical coherence length of storage-ring undulator x-ray beams so that the entirety of the coherent flux can be used for small angle multi-speckle x-ray photon correlation spectroscopy (XPCS) experiments. We find that the focused beam produced by a kinoform lens preserves the coherence of the incident unfocused beam and that at an appropriate distance downstream of the focus, the diverging beam produces speckles nearly identical to those produced by an equivalently-sized unfocused beam. We have also investigated the effect of imperfect beamline optics on the observed coherence properties of the beam. Via phase contrast imaging and beam-divergence measurements, we find that a horizontally-deflecting mirror in our beamline precludes us from seeing the true radiation source point but instead acts as an apparent source of fixed size at the center of our insertion device straight section. Finally, we discuss how expected near-future optimization of these optics will greatly benefit XPCS measurements performed at beamline 8-ID-I at the Advanced Photon Source.

Sandy, A. R.; Evans-Lutterodt, K.; Fezzaa, K.; Kim, S.; Narayanan, S.; Sprung, M.; Stein, A.; X-Ray Science Division; BNL; Gwangiu Inst. of Science and Technology

2007-01-01

68

Optimization of X-ray instrumentation in astrophysics  

E-print Network

Cadmium Zinc Telluride and Cadmium Telluride are the detector materials of choice for the detection of X-rays in the X-ray energy band E >= 5keV with excellent spatial and spectral resolution and without cryogenic cooling. Owing to recent breakthroughs in grazing incidence mirror technology, next-generation hard X-ray telescopes will achieve angular resolution between 5 and 10 arc seconds - about an order of magnitude better than that of the NuSTAR hard X-ray telescope. As a consequence, the next generation of X-ray telescopes will require pixelated X-ray detectors with pixels on a grid with a lattice constant of X-ray mission include studies and measurements of black hole spins, the cosmic evolution of super-massive black holes, active galactic nuclei feedback, and the behaviour of matter at very high densities. In this...

Zajczyk, Anna; Dowkontt, Paul; Guo, Qingzhen; Kislat, Fabian; Krawczynski, Henric; De Geronimo, Gianluigi; Li, Shaorui; Beilicke, Matthias

2015-01-01

69

X-Ray Spectroscopy at the TEXTOR-94 Tokamak  

NASA Astrophysics Data System (ADS)

Spectra of the 1s-2p resonance line of helium-like argon, Ar XVII, and the associated satellites in the narrow wavelength range from 3.9494 Å to 3.9944 Å have been observed at TEXTOR-94 with two high-resolution X-ray crystal spectrometers at Bragg angles near 54 degrees. Together, these instruments can be used as an X-ray polarimeter. The instruments are very sensitive to small amounts of argon; thus, a count rate of 4×105 photons/s, which corresponds to the maximum count rate capability of the presently used detectors, can be obtained for argon densities of less than 10-3 times the electron density, if the central electron temperature is about 1 keV. Up to 8192 spectra per discharge can be recorded allowing for the investigation of fast events during MHD activities. The instruments have been used to study the electron and ion behavior during internal sawtooth oscillations, which affect the confinement properties in the core of the plasma. The X-ray polarimeter at TEXTOR-94 is a unique diagnostic tool for the measurement of non-Maxwellian electron-velocity distributions, which can be produced in tokamak discharges in the presence of electric fields. First polarization measurements were performed during the flat-top phase in discharges with both pure ohmic heating and additional neutral-beam heating. These measurements showed that inhomogeneities in the emissivity profile can produce effects which look like polarization effects. No polarization was found when these source inhomogeneities were taken into account. The polarimeter is presently upgraded by an imaging X-ray crystal to facilitate polarization measurements. This will be important for the upcoming experiments with electron cyclotron heating at TEXTOR-94.

Bertschinger, G.; Biel, W.; Herzog, O.; Weinheimer, J.; Kunze, H.-J.; Bitter, M.

70

X-ray laser spectroscopy on lithium-like ions  

NASA Astrophysics Data System (ADS)

The Gesellschaft fuer Schwerionenforschung (GSI, Society for Heavy Ion Research) is currently the leading facility in the production of radioactive isotopes. Nuclear properties like charge radii, spin, and magnetic moments of exotic nuclei provide important data for testing of nuclear models. These properties are usually accessed by laser spectroscopy, which requires photon energies of around 100 eV in the case of lithium-like ions. We propose to use a transient gain X-ray laser (XRL) at the experimental storage ring (ESR) to perform this kind of spectroscopy. In this article we describe the planned experiments and give an overview of the current construction at GSI.

Neumayer, Paul; Alvarez, J.; Becker-de Mos, Bruno; Borneis, Stefan; Brueck, K.; Gaul, Erhard W.; Haefner, C.; Janulewicz, Karol A.; Kuehl, Thomas; Marx, Dieter; Reinhard, Irene; Tomaselli, Marco; Nickles, Peter V.; Sandner, Wolfgang; Seelig, Wolfgang

2001-12-01

71

Probing deeper by hard x-ray photoelectron spectroscopy  

SciTech Connect

We report an hard x-ray photoelectron spectroscopy method combining high excitation energy (15?keV) and improved modelling of the core-level energy loss features. It provides depth distribution of deeply buried layers with very high sensitivity. We show that a conventional approach relying on intensities of the core-level peaks is unreliable due to intense plasmon losses. We reliably determine the depth distribution of 1 ML La in a high-?/metal gate stack capped with 50?nm a-Si. The method extends the sensitivity of photoelectron spectroscopy to depths beyond 50?nm.

Risterucci, P.; Renault, O., E-mail: olivier.renault@cea.fr; Martinez, E.; Delaye, V. [CEA, LETI, MINATEC Campus, 38054 Grenoble Cedex 09 (France); Detlefs, B. [CEA, LETI, MINATEC Campus, 38054 Grenoble Cedex 09 (France); European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Zegenhagen, J. [European Synchrotron Radiation Facility, 6 rue Jules Horowitz, F-38043 Grenoble (France); Gaumer, C. [STMicroelectronics, 850 rue Jean Monnet, 38926 Crolles (France); Grenet, G. [Institut des Nanotechnologies de Lyon (INL), UMR CNRS 5270, Ecole Centrale de Lyon, 36, avenue Guy de Collongue 69 134 Ecully Cedex (France); Tougaard, S. [Department of Physics, Chemistry and Pharmacy, University of Southern Denmark, DK-5230 Odense M (Denmark)

2014-02-03

72

EUV, X-ray, and gamma-ray instrumentation for astronomy III. Proceedings.  

NASA Astrophysics Data System (ADS)

This conference proceedings contains papers describing the problems of instrumentation in the EUV to gamma-ray wavelength regime, and solutions to these problems for flight experiments. Technological developments of particular interest include increasing energy resolution in the X-ray regime for superconducting tunneling junctions and cyrogenic microcalorimeters, the increasing use of microstrip readouts in proportional counters, applications of CCDs to soft X-ray and UV detection, and high-spatial-resolution readout systems for microchannel plates. The topics represented in these conference proceedings are detailed as follows. Sessions 1 and 8, "Superconducting tunnel-junction detectors", describe work with superconducting tunneling junctions in X-ray spectroscopy, including junction arrays and new materials. Sessions 2, 4, and 11, "Spaceborne experiments and missions", encompass presentations on spaceflight instrumentation both flown and currently under development. Mission instruments described include ALEXIS, DXS, CUBIC, HEXTE, DMSP, SIGMA, Spectrum X-Gamma, SOHO, and AXAF, along with development of sounding rocket payloads, novel interferometric techniques, and an overview of NASA flight programs. Sessions 3 and 6, "Proportional-counter detectors", describe the development of proportional-counter techniques and counter windows. Particular issues of interest include the application of proportional counters in polarimetry and the increasing use of microstrip readout techniques. Session 5, "CCD detectors", discusses CCD detectors applied to X-ray and UV detection, with comparison to other detector types and description of CCD window technology. Session 7, "Microchannel-plate detectors", discusses the status of microchannel plates and microchannel-plate detector schemes. Recent developments in microchannel-plate technology regarding low noise, square pore, and gain characteristics are evaluated. Advances in image readout systems for applications in astrophysics are also discussed. Session 9, "Calorimeter detectors", details, advances in the development of low-temperature microcalorimeters with high-energy resolution in the X-ray regime. Session 10, "X-ray and gamma-ray spectroscopy and imaging techniques", details topics including phoswich detectors and gas scintillation proportional counters for high-energy detector systems.

Siegmund, O. H. W.

73

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

74

Soft x-ray spectroscopy of the Vela supernova remnant  

NASA Astrophysics Data System (ADS)

The CODEX sounding rocket payload was designed and flown to significantly improve spectral resolution of the Vela supernova remnant (SNR) in the soft x-ray (0.1--1.0 keV) bandpass. High spectral resolution (E/Delta E > 40) across its 3.25° x 3.25° field of view would disentangle thermal emission from nonthermal or line emission components to constrain the age when SNRs stop emitting nonthermal x-rays. Relatively recent observations have found significant nonthermal emission from remnants up to several kyr old, but CODEX encountered concurrent problems of higher noise and lower signal than expected, leaving the thermal versus nonthermal question unanswered in the 11 kyr-old Vela SNR. This thesis covers the motivation, design, and post-flight analysis of the CODEX instrument and data from its flight.

Zeiger, Benjamin R.

75

X-ray absorption spectroscopy of photoionised plasmas at Z  

NASA Astrophysics Data System (ADS)

Photoionised plasmas are found in astrophysical environments such as x-ray binaries, active galactic nuclei, and in the accretion disks of compact objects. The Z facility at Sandia National Laboratories is a powerful source of x-rays that enables us to produce and study in the laboratory photoionised plasmas relevant for astrophysics under well characterized conditions. We discuss an experimental and theory/modeling effort in which the intense x-ray flux emitted at the collapse of a z-pinch experiment conducted at Z is employed to produce a neon photoionized plasma. The broad-band x-ray radiation flux from the z-pinch is used to both create the neon photoionised plasma and provide a source of backlighting photons to study the atomic kinetics through K-shell line absorption spectroscopy. The plasma is contained in a cm-scale gas cell located at about 5 cm from the z-pinch, and the filling pressure is carefully monitored all the way to shot time since it determines the particle number density of the plasma. Time-integrated and gated transmission spectra are recorded with a TREX spectrometer equipped with two elliptically-bent crystals and a set of slits to record up to six spatially-resolved spectra per crystal in the same shot. The spectral resolution is approximately 1000. The transmission data shows line absorption transitions in several ionization stages of neon including Be-, Li-, He- and H-like Ne ions. Detailed modeling calculations of the absorption spectra are used to interpret and model the high-resolution transmission spectra recorded in the Z experiments with the goal of extracting the ion population distribution of the plasma. Furthermore, the analysis of the gated data provides a window into the dynamics of the photoionized plasma. The data analysis is performed with the aid of a novel application of genetic algorithms to plasma spectroscopy.

Mancini, R. C.

2011-06-01

76

X-ray Absorption Spectroscopy: a powerful tool for the investigation  

E-print Network

X-ray Absorption Spectroscopy: a powerful tool for the investigation of the role of metals is to illustrate the potentialities of X-ray Absorption Spectroscopy (XAS) to investigate structural properties Protein and Zinc ions 2 Introduction to the X-ray Absorption Spec- troscopy XAS uses Synchrotron Radiation

Morante, Silvia

77

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

78

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

E-print Network

There are four major X-ray satellites currently in operation, with two more shortly to follow, and several very ambitious observatories in various stages of planning. 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, 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.

Michael A. Nowak

2003-12-18

79

Growth and trends in Auger-electron spectroscopy and x-ray photoelectron spectroscopy for surface analysis  

NASA Astrophysics Data System (ADS)

A perspective is given of the development and use of surface analysis, primarily by Auger-electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS), for solving scientific and technological problems. Information is presented on growth and trends in instrumental capabilities, instrumental measurements with reduced uncertainties, knowledge of surface sensitivity, and knowledge and effects of sample morphology. Available analytical resources are described for AES, XPS, and secondary-ion mass spectrometry. Finally, the role of the American Vacuum Society in stimulating improved surface analyses is discussed.

Powell, C. J.

2003-09-01

80

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

81

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

82

Multi-criteria Search and Optimization: an Application to X-ray Plasma Spectroscopy  

E-print Network

Multi-criteria Search and Optimization: an Application to X-ray Plasma Spectroscopy Igor E 89557 Reno, NV 89557 Reno, NV 89557 golovkin@physics.unr.edu rcman@physics.unr.edu sushil@cs.unr.edu X-ray X-ray spectroscopic analysis has been widely used as a standard technique to determine temperature

Louis, Sushil J.

83

Phase-resolved X-ray spectroscopy and spectral energy distribution of the X-ray soft polar RS Caeli  

NASA Astrophysics Data System (ADS)

Context. RS Cae is the third target in our series of XMM-Newton observations of soft X-ray-dominated polars. Aims: Our observational campaign aims to better understand and describe the multiwavelength data, the physical properties of the system components, and the short- and long-term behavior of the component fluxes in RS Cae. Methods: We employ stellar atmosphere, stratified accretion-column, and widely used X-ray spectral models. We fit the XMM-Newton spectra, model the multiband light curves, and opt for a mostly consistent description of the spectral energy distribution. Results: Our XMM-Newton data of RS Cae are clearly dominated by soft X-ray emission. The X-ray light curves are shaped by emission from the main accretion region, which is visible over the whole orbital cycle, interrupted only by a stream eclipse. The optical light curves are formed by cyclotron and stream emission. The XMM-Newton X-ray spectra comprise a black-body-like and a plasma component at mean temperatures of 36 eV and 7 keV. The spectral fits give evidence of a partially absorbing and a reflection component. Multitemperature models, covering a broader temperature range in the X-ray emitting accretion regions, reproduce the spectra appropriately well. Including archival data, we describe the spectral energy distribution with a combination of models based on a consistent set of parameters and derive a lower limit estimate of the distance d ? 750 pc. Conclusions: The high bolometric soft-to-hard flux ratios and short-term variability of the (X-ray) light curves are characteristic of inhomogeneous accretion. RS Cae clearly belongs in the group of polars that show a very strong soft X-ray flux compared to their hard X-ray flux. The different black-body fluxes and similar hard X-ray and optical fluxes during the XMM-Newton and ROSAT observations show that soft and hard X-ray emission are not directly correlated. Based on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA Member States and NASA.

Traulsen, I.; Reinsch, K.; Schwope, A. D.; Schwarz, R.; Walter, F. M.; Burwitz, V.

2014-02-01

84

Electronic Structure of In2O3 from Resonant X-ray Emission Spectroscopy  

SciTech Connect

The valence and conduction band structures of In2O3 have been measured using a combination of valence band x-ray photoemission spectroscopy, O K-edge resonant x-ray emission spectroscopy, and O K-edge x-ray absorption spectroscopy. Excellent agreement is noted between the experimental spectra and O 2p partial density of states calculated within hybrid density functional theory. Our data are consistent with a direct band gap for In2O3.

Piper, L.; DeMasi, A; Cho, S; Smith, K; Fuchs, F; Bechstedt, F; Korber, C; Klein, A; Payne, D; Egdell, R

2009-01-01

85

Chandra X-Ray Imaging and Spectroscopy of the M87 Jet and Nucleus  

Microsoft Academic Search

We report X-ray imaging spectroscopy of the jet of M87 at subarcsecond resolution with the Chandra X-ray Observatory. The galaxy nucleus and all the knots seen at radio and optical wavelengths, as far from the nucleus as knot C, are detected in the X-ray observations. There is a strong trend for the ratio of X-ray-to-radio, or optical, flux to decline

A. S. Wilson; Y. Yang

2002-01-01

86

Theoretical X-ray Spectroscopy of Iron Complexes.  

E-print Network

??This thesis discusses both theoretical developments for the calculation of X-ray spectra and applications of quantum-chemical methods to the calculation and interpretation of experimental X-ray… (more)

Atkins, Andrew J.

2013-01-01

87

Hindawi Publishing Corporation X-Ray Optics and Instrumentation  

E-print Network

pages doi:10.1155/2010/784732 Research Article Elliptically Bent X-Ray Mirrors with Active Temperature of the mirror design is an active temperature stabilization based on a Peltier element attached directly to the mirror body. The design and materials have been carefully optimized to provide high heat conductance

88

XEUS The X-ray Evolving Universe Spectroscopy Mission  

E-print Network

XEUS is under study by ESA as part of the Horizon 2000+ program to utilize the International Space Station (ISS) for astronomical applications. XEUS will be a long-term X-ray observatory with an initial mirror area of 6m2 at 1 keV that will be grown to 30m2 following a visit to the ISS. The 1 keV spatial resolution is expected to be 2-5'' HEW. XEUS will consist of separate detector and mirror spacecraft aligned by active control to provide a focal length of 50m. A new detector spacecraft, complete with the next generation of instruments, will also be added after visiting the ISS. The limiting sensitivity will then be ~4 10-18 erg/cm2/s - around 250 times better than XMM, allowing XEUS to study the properties of the hot baryons and dark matter at high redshift.

Parmar, A N; Bavdaz, M; Hasinger, G; Arnaud, M; Barcons, X; Barret, D; Blanchard, A; Böhringer, H; Cappi, M; Comastri, A; Courvoisier, Thierry J L; Fabian, A C; Griffiths, R; Malaguti, P; Mason, K O; Ohashi, T; Paerels, F B S; Piro, L; Schmitt, J; Van der Klis, M; Ward, M

1999-01-01

89

XEUS - The X-ray Evolving Universe Spectroscopy Mission  

E-print Network

XEUS is under study by ESA as part of the Horizon 2000+ program to utilize the International Space Station (ISS) for astronomical applications. XEUS will be a long-term X-ray observatory with an initial mirror area of 6m2 at 1 keV that will be grown to 30m2 following a visit to the ISS. The 1 keV spatial resolution is expected to be 2-5'' HEW. XEUS will consist of separate detector and mirror spacecraft aligned by active control to provide a focal length of 50m. A new detector spacecraft, complete with the next generation of instruments, will also be added after visiting the ISS. The limiting sensitivity will then be ~4 10-18 erg/cm2/s - around 250 times better than XMM, allowing XEUS to study the properties of the hot baryons and dark matter at high redshift.

A. N. Parmar; T. Peacock; M. Bavdaz; G. Hasinger; M. Arnaud; X. Barcons; D. Barret; A. Blanchard; H. Bohringer; M. Cappi; A. Comastri; T. Courvoisier; A. C. Fabian; R. Griffiths; P. Malaguti; K. O. Mason; T. Ohashi; F. Paerels; L. Piro; J. Schmitt; M. van der Klis; M. Ward

1999-11-29

90

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

91

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

92

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

93

X-ray photon correlation spectroscopy in microfluidic ssytems  

NASA Astrophysics Data System (ADS)

We present a new experimental method that combines X-ray photon Correlation Spectroscopy (XPCS) and microfluidics and allows the direct measurement of the mesoscale dynamics of various soft matter systems (e.g. colloids, polymers, biological molecules like proteins, RNA, etc.) under flow conditions. Such a setup reduces the risk of beam damage and also allows time-resolved studies of various processes taking place in mixing flowcells. In the experiments reported here, we have used colloidal suspensions of hard-spehere systems, and studied their Brownian dynamics under laminar flow. Our experimental results and theoretical predictions show that the diffusive (Brownian) dynamics of the colloids can be decoupled from the flow-induced, convective dynamics.

Fluerasu, Andrei

2007-03-01

94

Geophysics Studies With High-Resolution X-ray Spectroscopy  

NASA Astrophysics Data System (ADS)

The introduction of high-resolution (about 1 meV) inelastic x-ray scattering techniques to third generation synchrotron radiation facilities around the world has been very successful. New opportunities for the study of vibrational properties of condensed matter have emerged for research areas like biophysics, geophysics, and nanoscience. In particular, the determination of phonon dispersion relations with momentum-resolved inelastic x-ray scattering (IXS), of vibrational density of states with nuclear resonant inelastic x-ray scattering (NRIXS), and of the determination of valences, spin states, and magnetic ordering with synchrotron Mössbauer spectroscopy (SMS), all under extreme conditions, provided novel and often remarkable results in the scientific area of geophysics [1]. In this contribution, the combination of high-resolution spectroscopy with diamond anvil cell technology and its impact on the geoscientific area will be discussed. Nuclear resonant spectroscopy (NRIXS & SMS) under extreme conditions has become a key method to provide sound velocities and elasticity on iron, iron alloys, and iron oxides, to study valence and high-spin to low-spin transitions in lower mantle minerals, and to investigate magnetic ordering transitions of iron-bearing materials. Its sensitivity in combination with isotope selectivity allowed investigations on materials under high pressures using diamond anvil cells and Laser heating. Examples will illustrate the present and potential future use of nuclear resonant spectroscopy in the Earth and planetary sciences. Momentum resolved IXS detects phonon dispersions and has been applied to Earth materials like iron metal and MgO under high pressure in diamond anvil cells. In single crystals, the dispersion of the acoustic phonons at low energies provides sound velocities for various directions and potentially the elastic tensor of the material. The technical requirements for nuclear resonant andmomentum resolved IXS methods have favored the diamond anvil cell for generation of high pressures. The x-ray energies are typically between 10 keV and 30 keV, and the high-pressure device has to accommodate sufficiently low absorption at those energies. In addition, momentum-resolved IXS needs access to a plane with 20-30 degree opening angle. NRIXS experiments require access to a significant solid angle. These conditions have been more readily met by diamond anvil cells. Here we will discuss the possibility of using a multi-anvil device instead and evaluate the conditions for IXS experiments in such apparatus. This work is supported by the U. S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-06CH11357. References [1] W. Sturhahn and J.M. Jackson, in Advances in High-Pressure Mineralogy, E.Ohtani, ed., Special Paper 421, 157-174 (2007)

Sturhahn, W.

2009-05-01

95

Software System for the Calibration of X-Ray Measuring Instruments  

NASA Astrophysics Data System (ADS)

A software system that facilities the calibration of X-ray measuring instruments used in medical applications is presented. The Secondary Standard Dosimetry Laboratory (SSDL) of the Nuclear Research National Institute in México (ININ in Spanish), supports activities concerning with ionizing radiations in medical area. One of these activities is the calibration of X-ray measuring instruments, in terms of air kerma or exposure by substitution method in an X-ray beam at a point where the rate has been determined by means of a standard ionization chamber. To automatize this process, a software system has been developed, the calibration system is composed by an X-ray unit, a Dynalizer IIIU X-ray meter by RADCAL, a commercial data acquisition card, the software system and the units to be tested and calibrated. A quality control plan has been applied in the development of the software system, ensuring that quality assurance procedures and standards are being followed.

Gaytán-Gallardo, E.; Tovar-Muñoz, V. M.; Cruz-Estrada, P.; Vergara-Martínez, F. J.; Rivero-Gutiérrez, T.

2006-09-01

96

X-Ray diffraction and Fourier transformation infrared spectroscopy studies of copper (II) thiourea chloro and sulphate complexes  

NASA Astrophysics Data System (ADS)

Copper (II) thiourea complexes were synthesized by chemical route method. To analyze the samples, X-Ray diffraction and Fourier transformation infrared spectroscopy method have been used. XRD analysis shows that sample is crystalline in nature and having particle size in the range of nanometres. FTIR spectroscopy shows the organic and inorganic compounds present in the sample. The X-ray diffraction pattern (XRD) using Bruker D-8 advance instrument and Infrared spectra of the complexes were obtained by KBr disc technique by using VERTEX 70 (Bruker).

Mishra, Ashutosh; Dwivedi, Jagrati; Shukla, Kritika; Malviya, Pramod

2014-09-01

97

X-Ray Spectroscopy of Nearby Young Stars in the TW Association  

NASA Astrophysics Data System (ADS)

To improve our understanding of X-ray emitting regions of T Tauri stars (TTS) we are conducting an X-ray spectroscopic study of the TW Hya Association (TWA). X-ray spectra of TWA stars provide plasma diagnostics that yield insights into the origin of X-ray emission from young stars and are diagnostic of accretion processes. The co-evolutionary population of 10 Myr-old TTS, their proximity, and their lack of X-ray absorbing cloud material make the TWA well suited to X-ray spectroscopy. Here, our focus is on a binary TTS system, TWA-19AB, the only TWA system known to include a G-star, important for determining the role of mass in pre-main-sequence X-ray emission. The close (40") K7 companion will provide an X-ray spectrum of a weakly accreting star similar to TW Hya itself.

Canizares, Claude

2009-09-01

98

High-efficiency blazed transmission gratings for high-resolution soft x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

High-resolution spectroscopy of astrophysical sources is the key to gaining a quantitative understanding of the history, dynamics, and current conditions of the cosmos. A large-area (> 1,000 cm2), high resolving power (R = ?/?? > 3,000) soft x-ray spectrometer that covers the lines of C, N, O, Ne and Fe ions is the ideal tool to address a number of high-priority sciences questions from the 2010 Decadal Survey, such as the connection between super-massive black holes and large-scale structure via cosmic feedback, the evolution of large-scale structure, the behavior of matter at high densities, and the conditions close to black holes. Numerous mission concepts that meet these requirements have been studied and proposed over the last few years, including grating instruments for the International X-ray Observatory. Nevertheless, no grating missions are currently approved. To improve the chances for future soft x-ray grating spectroscopy missions, grating technology has to progress and be advanced to higher TRLs. We have developed Critical-Angle Transmission (CAT) gratings that combine the advantages of blazed reflection gratings (high efficiency, use of higher diffraction orders) with those of conventional transmission gratings (low mass, relaxed alignment tolerances and temperature requirements, transparent at higher energies). A CAT grating-based spectrometer can provide performance 1-2 orders of magnitude better than current grating instruments on Chandra and Newton-XMM with minimal resource requirements. We have fabricated large-area free-standing CAT gratings with minimal integrated support structures from silicon-on-insulator wafers using advanced lithography and a combination of deep reactive-ion and wet etching, and will present our latest x-ray test results showing record high diffraction efficiencies in blazed orders.

Heilmann, Ralf K.; Bruccoleri, Alexander R.; Schattenburg, Mark L.

2015-01-01

99

Application of X-ray synchrotron microscopy instrumentation in biology  

SciTech Connect

X-ray micro-fluorescence imaging technique has been used as a significant tool in order to investigate minerals contents in some kinds of materials. The aim of this study was to evaluate the elemental distribution of calcium and zinc in bone substitute materials (nano-hydroxyapatite spheres) and cortical bones through X-Ray Micro-fluorescence analysis with the increment of Synchrotron Radiation in order to evaluate the characteristics of the newly formed bone and its interface, the preexisting bone and biomaterials by the arrangement of collagen fibers and its birefringence. The elemental mapping was carried out at Brazilian Synchrotron Light Laboratory, Campinas - Sao Paulo, Brazil working at D09-XRF beam line. Based on this study, the results suggest that hydroxyapatite-based biomaterials are biocompatible, promote osteo-conduction and favored bone repair. (authors)

Gasperini, F. M. [Medical Science Program, Fluminense Federal Univ., Niteroi (Brazil); Pereira, G. R. [Dept. of Metallurgical and Materials Engineering, Federal Univ. of Rio de Janeiro (Brazil); Granjeiro, J. M. [Molecular and Cell Biology Dept., Fluminense Federal Univ., Niteroi, Rio de Janeiro (Brazil); Calasans-Maia, M. D. [Oral Surgery Dept., Fluminense Federal Univ., Niteroi, Rio de Janeiro (Brazil); Rossi, A. M. [Biomaterials Laboratory, Brazilian Center of Physics Research, Rio de Janeiro (Brazil); Perez, C. A. [Brazilian Synchrotron Laboratory, Campinas, Sao Paulo (Brazil); Lopes, R. T.; Lima, I. [Nuclear Engineering Laboratory, Federal Univ. of Rio de Janeiro (Brazil)

2011-07-01

100

Characterization of phases formed in the iron carbide process by X-ray diffraction, mossbauer, X-ray photoelectron spectroscopy, and raman spectroscopy analyses  

Microsoft Academic Search

Iron carbide was prepared by iron ore reduction and iron cementation using Ar-H2-CH4 gas mixture with and without sulfur. Phases formed in the reduction\\/cementation process were examined by X-ray diffraction\\u000a (XRD), Mossbauer, and Raman spectroscopy. The sample surface was also analyzed by X-ray photoelectron spectroscopy (XPS).\\u000a XRD and Mossbauer analyses showed that iron oxide was first reduced to metallic iron,

Oleg Ostrovski; Jianqiang Zhang; Stuart Thomson; Russell Howe

2001-01-01

101

Diagnostics of the Solar Wind Composition by X-Ray Spectroscopy of Comets from Chandra X-Ray Observatory  

NASA Astrophysics Data System (ADS)

X-rays are excited in comets by charge exchange of the solar wind heavy ions with cometary neutrals, which are mostly H2O, OH, and O. The excitation cross sections are known with a reasonable accuracy from theory and laboratory studies. The advanced capabilities of the Chandra X-ray Observatory (CXO) and the recently developed method of analysis [Krasnopolsky et al. Icarus 160, 437, 2002] of the CXO observations of comets result in identification of the emissions excited by the solar wind ions O+8, O+7, C+6, C+5, Ne+9, Ne+8, Mg+10, Mg+9, Mg+8, and Si+9. The CXO observations of comets McNaught-Hartley (MH) and LINEAR S4 (S4) have been processed using this method to compare X-rays from those comets and the composition of the solar wind. The X-ray isophotes are crescent-like in S4 and more circular in MH because of the different phase angles (98° and 44° , respectively). The peak X-ray brightness is greater in S4 than that in MH by a factor of 1.5 and smaller by a factor of 1.7 after the correction for heliocentric distance. The X-ray luminosities of MH and S4 are equal to 8.6 and 1.4*E-15 erg s-1 inside the apertures of ? = 1.5 and 0.5*E4 km, respectively. (Brightness is 0.2 of the peak value at these ? .) Efficiencies of X-ray excitation corrected to the solar wind flow are similar and equal to 4.3*E-14 erg AU3/2 in both comets. This confirms the solar wind excitation of X-rays in comets. The line identification is given. Ion ratios in the solar wind have been extracted from the spectra. O+8/O+7 is equal to 0.29+/-0.04 and 0.14+/-0.03 in MH and S4. These ratios correspond to T=2.17 and 1.93*E6K and correlate with the solar wind speed of 390 and 500 km s-1 in MH and S4, respectively. Ne+9/O+7 is (15+/-6)*E-3 and (19+/-7)*E-3, and C+6/O+7 is 0.7+/-0.2 in both MH and S4. X-ray spectroscopy of comets may be used as a diagnostic tool to study the solar wind composition.

Krasnopolsky, V. A.

2003-12-01

102

X-ray absorption spectroscopy of bacterial sulfur globules  

SciTech Connect

Sulfur K-edge X-ray absorption spectroscopy is a powerful in situ probe of sulfur biochemistry in intact cells and tissues. Under favorable circumstances the technique can provide quantitative information on the chemical identify of the sulfur species that are present in a sample. Prange et al. have recently reported an X-ray absorption spectroscopic study of bacterial sulfur storage globules. Unfortunately there are substantial problems with the experimental technique employed that, they contend, lead to completely erroneous conclusions. In the more recent of their two papers Prange et al. employed a curve-fitting method similar to that used by us (for more than 10 years). In essence, the method employs simply fitting a linear combination of the spectra of standard compounds to that of the unknown, in this case cultures of bacterial cells. This type of analysis can provide quantitative estimates of the individual sulfur types in the sample, but is critically dependent upon the choice of reference spectra. Prange et al. deduce substantial differences between the chemical forms of sulfur stored in the globules of different organisms; they conclude that the globules of Beggiatoa alba and Thiomargarita namibiensis contain cyclo-octasulfur (S{sub 8}), while those of other organisms contain polythionates (Acidithiobacillus ferrooxidans) and polymeric sulfur (e.g. Allochromatium vinosum). This is in contradiction with an earlier study, in which they found that sulfur in all globule species examined resembled that expected for various sized spherical particles of S{sub 8}. The discrepancy is due to an experimental artefact in the work of Prange et al. arising from their choice of transmittance detection, which is also discussed.

George, Graham N.

2002-08-01

103

X-Ray Absorption Spectroscopy of Strontium(II) Coordination.  

PubMed

Sorption of dissolved strontium on kaolinite, amorphous silica, and goethite was studied as a function of pH, aqueous strontium concentration, the presence or absence of atmospheric CO(2) or dissolved phosphate, and aging over a 57-day period. Selected sorption samples ([Sr(aq)](i) approximately 0.5-1x10(-3) m) were examined with synchrotron X-ray absorption spectroscopy (XAS) at low (13-23 K) and room temperatures to determine the local molecular coordination around strontium. Quantitative analyses of the extended X-ray absorption fine structure (EXAFS) of kaolinite, amorphous silica, and most goethite sorption samples showed a single first shell of 9-10 (+/-1) oxygen atoms around strontium at an average Sr-O bond-distance of 2.61 (+/-0.02) Å, indicating hydrated surface complexes. The EXAFS spectra were unchanged after reaction for up to 57 days. Likewise, in kaolinite sorption samples prepared in 100% nitrogen atmosphere, the presence of dissolved phosphate (0.5x10(-3) m) in addition to strontium did not change the local coordination around strontium. In two goethite sorption samples reacted in air at pH approximately 8.5, the EXAFS spectra (collected at low and room temperature) clearly showed that the local structure around strontium is that of strontianite (SrCO(3)(s)). We also noted an increase in strontium uptake on goethite in the presence of atmospheric CO(2) in batch experiments, relative to CO(2)-free experiments. These observations suggest that sorption of carbonate may nucleate the precipitation of SrCO(3) in the pH range in which carbonate sorption on goethite is near a maximum. At higher pH, carbonate surface sorption decreases as dissolved CO(2) decreases. For goethite sorption samples above pH 8.6, hydrated surface complexes, rather than a precipitate, were observed in the EXAFS spectra. Copyright 2000 Academic Press. PMID:10662515

Sahai; Carroll; Roberts; O'Day

2000-02-15

104

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

105

Metal binding in proteins: machine learning complements X-ray absorption spectroscopy  

E-print Network

Metal binding in proteins: machine learning complements X-ray absorption spectroscopy Marco Lippi1 diseases for which medicine is still seeking an effective treatment, such as Parkinson's or Alzheimer's [2. Experimental methods. High-throughput techniques based on X-ray absorp- tion spectroscopy [3] (HT-XAS) allow

Passerini, Andrea

106

Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-Ray (EDX) Spectroscopy  

E-print Network

Field Emission Scanning Electron Microscopy (FE-SEM) and Energy Dispersive X-Ray (EDX) Spectroscopy The materials characterization facility is equipped with a Hitachi S-4700 Field Emission Scanning Electron Electron Microscope (FE-SEM). The FE-SEM is equipped with EDAX Energy Dispersive X-Ray (EDX) spectroscopy

Gelfond, Michael

107

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

108

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

SciTech Connect

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. [Department of Physics, Yale University, New Haven, Connecticut 06520 and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Departments of Physics and Applied Physics, Yale University, New Haven, Connecticut 06520 (United States)

2004-11-01

109

CXO X-ray spectroscopy of comets and abundances of heavy ions in the solar wind  

NASA Astrophysics Data System (ADS)

X-rays from comets originate in charge exchange between heavy ions of the solar wind and cometary species. Spectra of nine comets observed by the Chandra X-ray Observatory (CXO) are analyzed using the time-dependent instrument sensitivity and the energy-dependent spectral resolution. X-ray emissions are extracted from the spectra in the range of 150-1100 eV using the ?2-fitting. Production of X-rays varies in the observed comets by a factor of 500 from 4.4 × 1013 erg s-1 in Comet 73P to 2.2 × 1016 erg s-1 in Comet Ikeya-Zhang. The measured solar wind flow varies within a factor of 20, being the weakest in Comet 73P and the strongest in 9P/Tempel 1. The retrieved X-ray line intensities vary within a factor of 5 × 104. These lines above 300 eV are attributed to emissions of the H- and He-like ions, and laboratory data on the excitation cross sections for these emissions (Greenwood et al. [2000]. Astrophys. J. 533, L175-L178) are used to convert the observed emissions into abundances of heavy ions in the solar wind. Continuity equations for charge exchange in comets are solved analytically and result in relationships between the X-ray emissions and the ion fluxes. The flux of O7+ scaled to 1 AU varies within a factor of 35 with a mean value of 1.6 × 104 cm-2 s-1. The retrieved ratios of O8+/O7+, C6+/C5+, Ne10+/Ne9+, C6+/O7+, N6+/O7+, and Ne9+/O7+ demonstrate significant variations, while their mean values for O, C, and N agree with those recommended by Schwadron and Cravens (Schwadron and Cravens [2000]. Astrophys. J. 544, 558-566) for the slow and fast solar wind. (Data on Ne9+ and Ne10+ are lacking in Scwadron and Cravens (Schwadron and Cravens [2000]. Astrophys. J. 544, 558-566).) The results are compared with the ion ratios from Bodewits et al. (Bodewits et al. [2007]. Astron. Astrophys. 469, 1183-1195) that were obtained from the same CXO spectra of comets, and some significant differences are briefly discussed. CXO X-ray spectroscopy of comets is a diagnostic tool to study the composition of the solar wind and its variations.

Krasnopolsky, Vladimir A.

2015-02-01

110

Combined measurement of X-ray photon correlation spectroscopy and diffracted X-ray tracking using pink beam X-rays.  

PubMed

Combined X-ray photon correlation spectroscopy (XPCS) and diffracted X-ray tracking (DXT) measurements of carbon-black nanocrystals embedded in styrene-butadiene rubber were performed. From the intensity fluctuation of speckle patterns in a small-angle scattering region (XPCS), dynamical information relating to the translational motion can be obtained, and the rotational motion is observed through the changes in the positions of DXT diffraction spots. Graphitized carbon-black nanocrystals in unvulcanized styrene-butadiene rubber showed an apparent discrepancy between their translational and rotational motions; this result seems to support a stress-relaxation model for the origin of super-diffusive particle motion that is widely observed in nanocolloidal systems. Combined measurements using these two techniques will give new insights into nanoscopic dynamics, and will be useful as a microrheology technique. PMID:23955045

Shinohara, Yuya; Watanabe, Akira; Kishimoto, Hiroyuki; Amemiya, Yoshiyuki

2013-09-01

111

SS433 Jet Diagnostics using Chandra X-ray Spectroscopy  

Microsoft Academic Search

The unusual X-ray binary SS 433 has been observed with the Chandra X-ray observatory on four occasions at different orbital and precessional phases. These data have provided excellent views of the hottest parts of the oppositely directed jets. Emission line widths directly provide the opening angle of the jet. Most importantly, we can also determine the composition, density, temperature, and

Herman L. Marshall; C. R. Canizares; N. S. Schulz; M. A. Nowak; S. Heinz; T. C. Hillwig; A. J. Mioduszewski

2006-01-01

112

LBT & Image "X-RAY SPECTROSCOPY OF GOLD  

E-print Network

NANOPARTICLES · Nanoparticles- common in biomedical applications · Radiation therapy with nanoparticles embedded transitions, such as 1s-2p, in heavy elements absorb or produce high energy X-rays heavy elements are widely of photons and electrons 2 #12;PHOTOIONIZATION: X(ion) + h X+ + e K-SHELL EDGE EFFECT ON X-RAY ABSORPTION

Nahar, Sultana Nurun

113

X-ray/EUV optics for astronomy and microscopy  

SciTech Connect

The proceedings of this book are organized under the following headings: X-Ray/EUV zone plates, filters, and windows; X-Ray/EUV microscopes, telescopes, and monochromators; Design, characterization and test of multilayer optics; Fabrication of x-ray/EUV multilayer optics; Design, characterization, and test of grazing incidence x-ray optics; Fabrication of grazing incidence x-ray optics; X-ray/EUV space observations and missions; Test and calibration of x-ray/EUV instruments; X-ray polarimetry; X-ray/EUV spectroscopy and instruments.

Hoover, R.B.

1989-01-01

114

X-ray photoelectron spectroscopy of etched ZnSe  

NASA Astrophysics Data System (ADS)

To produce longitudinal ZnSe laser structures the GaAs substrate must be removed from the MBE grown layers. When an aqueous solution of sulfuric acid and hydrogen peroxide was used for this purpose, a red film was left on the surface of the ZnSe. X-ray photoelectron spectroscopy was used to examine the wafers before etching, after etching and after etching followed by heating in vacuum or in an argon atmosphere. The as-polished surface contained Se in two different chemical states: ZnSe and Se oxide. The etch predominantly removed the Zn leaving a red Se-rich surface with mostly Se-Se bonding. The Zn Auger parameter decreased toward that of the oxide. The etched surface could be restored to ZnSe by heating in vacuum but not in an argon atmosphere. The one heated in the argon showed the Se Auger parameter approaching that of ZnSe while the Zn Auger parameter increased past that of ZnSe toward metallic Zn.

McGee, T. F.; Cornelissen, H. J.

1989-01-01

115

CdZnTe detector in diagnostic x-ray spectroscopy.  

PubMed

A method to utilize CdZnTe (CZT) detectors in diagnostic x-ray spectroscopy is described in this article. Spectral distortion due to transmission of primary x rays, the escape of cadmium- and tellurium-K fluorescent x rays, and tailing was severe in measured x-ray spectra. Therefore, correction for the distortion was performed with the stripping method using response functions. The response functions were calculated with the Monte Carlo method. The Hecht equation was employed to approximate the effects of carrier trapping in the calculations. The parameters in the Hecht equation, the mean-free path (lambda) of electrons and holes, were determined such that the tailing in calculated response functions fit that in measured gamma-ray spectra. Corrected x-ray spectra agreed well with the reference spectra measured with an HPGe detector. The results indicate that CZT detectors are suitable for diagnostic x-ray spectroscopy with appropriate corrections. PMID:12148722

Miyajima, Satoshi; Imagawa, Kotaro; Matsumoto, Masao

2002-07-01

116

The X-Ray Observatory Suzaku  

Microsoft Academic Search

High-sensitivity wide-band X-ray spectroscopy is the key feature of the Suzaku X-ray observatory, launched on 2005 July 10. This paper summarizes the spacecraft, in-orbit performance, operations, and data processing that are related to observations. The scientific instruments, the high-throughput X-ray telescopes, X-ray CCD cameras, non-imaging hard X-ray detector are also described.

Kazuhisa Mitsuda; Mark Bautz; Hajime Inoue; Richard L. Kelley; Katsuji Koyama; Hideyo Kunieda; Kazuo Makishima; Yoshiaki Ogawara; Robert Petre; Tadayuki Takahashi; Hiroshi Tsunemi; Nicholas E. White; Naohisa Anabuki; Lorella Angelini; Keith Arnaud; Hisamitsu Awaki; Aya Bamba; Kevin Boyce; Gregory V. Brown; Kai-Wing Chan; Jean Cottam; Tadayasu Dotanli; John Doty; Ken Ebisawa; Yuichiro Ezoe; Andrew C. Fabian; Enectali Figueroa; Ryuichi Fujimoto; Yasushi Fukazawa; Tae Furusho; Akihiro Furuzawa; Keith Gendreau; Richard E. Griffiths; Yoshito Haba; Kenji Hamaguchi; Ilana Harrus; Günther Hasinger; Isamu Hatsukade; Kiyoshi Hayashida; Patrick J. Henry; Junko S. Hiraga; Stephen S. Holt; Ann Hornschemeier; John P. Hughes; Una Hwang; Manabu Ishida; Yoshitaka Ishisaki; Naoki Isobe; Masayuki Itoh; Naoko Iyomoto; Steven M. Kahn; Tuneyoshi Kamae; Hideaki Katagiri; Jun Kataoka; Haruyoshi Katayama; Nobuyuki Kawai; Caroline Kilbourne; Kenzo Kinugasa; Steve Kissel; Shunji Kitamoto; Mitsuhiro Kohama; Takayoshi Kohmura; Motohide Kokubun; Taro Kotani; Jun'ichi Kotoku; Aya Kubota; Greg M. Madejski; Yoshitomo Maeda; Fumiyoshi Makino; Alex Markowitz; Chiho Matsumoto; Hironori Matsumoto; Masaru Matsuoka; Kyoko Matsushita; Dan McCammon; Tatehiko Mihara; Kazutami Misaki; Emi Miyata; Tsunefumi Mizuno; Koji Mori; Hideyuki Mori; Mikio Morii; Harvey Moseley; Koji Mukai; Hiroshi Murakami; Toshio Murakami; Richard Mushotzky; Fumiaki Nagase; Masaaki Namiki; Hitoshi Negoro; Kazuhiro Nakazawa; John A. Nousek; Takashi Okajima; Yasushi Ogasaka; Takaya Ohashi; Tai Oshima; Naomi Ota; Masanobu Ozaki; Hideki Ozawa; Arvind N. Parmar; William D. Pence; F. Scott Porter; James N. Reeves; George R. Ricker; Ikuya Sakurai; Wilton T. Sanders; Atsushi Senda; Peter Serlemitsos; Ryo Shibata; Yang Soong; Randall Smith; Motoko Suzuki; Andrew E. Szymkowiak; Hiromitsu Takahashi; Toru Tamagawa; Keisuke Tamura; Takayuki Tamura; Yasuo Tanaka; Makoto Tashiro; Yuzuru Tawara; Yukikatsu Terada; Yuichi Terashima; Hiroshi Tomida; Ken'ichi Torii; Yohko Tsuboi; Masahiro Tsujimoto; Takeshi Go Tsuru; Martin J. L.. Turner; Yoshihiro Ueda; Shiro Ueno; Masaru Ueno; Shin'ichiro Uno; Yuji Urata; Shin Watanabe; Norimasa Yamamoto; Kazutaka Yamashita; Noriko Y. Yamasaki; Koujun Yamashita; Makoto Yamauchi; Shigeo Yamauchi; Tahir Yaqoob; Daisuke Yonetoku; Atsumasa Yoshida

2007-01-01

117

X-RAY ANALYSIS BY ELECTRON SPECTROSCOPY (*) Groupe de Spectroscopie Electronique,  

E-print Network

carbon film (conver- ter) illuminated by X-rays emitted by an aluminium- magnesium anode. For further spectrum obtained with a carbon converter irradiated by a Mg-Al alloy anode. instead of the classical-ray photoelectron microscopy and spectroscopy (I) : (D aluminium anode (2) spe- cimen ; b) for XAES : (T) specimen

Paris-Sud XI, Université de

118

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

PubMed

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(5)Si(2)Ge(2) giant magnetocaloric material. PMID:17764332

Haskel, D; Tseng, Y C; Lang, J C; Sinogeikin, S

2007-08-01

119

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

120

Electrochemical discharge of nanocrystalline magnetite: structure analysis using X-ray diffraction and X-ray absorption spectroscopy.  

PubMed

Magnetite (Fe3O4) is an abundant, low cost, environmentally benign material with potential application in batteries. Recently, low temperature coprecipitation methods have enabled preparation of a series of nanocrystalline magnetite samples with a range of crystallite sizes. Electrochemical cells based on Li/Fe3O4 show a linear increase in capacity with decreasing crystallite size at voltages ?1.2 V where a 2× capacity improvement relative to commercial (26.2 nm) magnetite is observed. In this report, a combination of X-ray powder diffraction (XRD) and X-ray absorption spectroscopy (XAS) is used to measure magnetite structural changes occurring upon electrochemical reduction, with parent Fe3O4 crystallite size as a variable. Notably, XAS provides evidence of metallic iron formation at high levels of electrochemical reduction. PMID:24077019

Menard, Melissa C; Takeuchi, Kenneth J; Marschilok, Amy C; Takeuchi, Esther S

2013-11-14

121

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

NASA Astrophysics Data System (ADS)

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 × 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.; Hönicke, P.; Müller, M.; Pollakowski, B.; Reinhardt, F.; Weser, J.

2013-04-01

122

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

123

The First X-Ray Spectroscopy Observation of WO Binary  

NASA Astrophysics Data System (ADS)

We propose a 50 ksec XMM-Newton observation of a massive stellar binary WR30a. The binary consists of a WO-type Wolf-Rayet star and an O type companion. A WO-type star is generally thought to be the final evolutionary stage in the WR phase, and has the fastest stellar wind with average terminal velocity approx 5000 km s-1. To date, there is no report on X-ray detection from WO-type stars, while intensive studies have been made for WN- and WC- type stars with X-rays. Our aim is to detect X-rays from a WO-type binary for the first time, and to compare the X-ray properties (especially the plasma temperature) with those of well-researched two types (WN and WC).

Maeda, Yoshitomo

2008-10-01

124

The first X-ray spectroscopy observation of WO binary  

NASA Astrophysics Data System (ADS)

We propose a 50 ksec XMM-Newton observation of a massive stellar binary WR30a. The binary consists of a WO-type Wolf-Rayet star and an O supergiant. A WO-type star is generally thought to be the final evolutionary stage in the W-R phase, and has the fastest stellar wind with average terminal velocity ~5000 km/s. To date, there is no report on X-ray detection from WO-type binaries, while intensive studies have been made for those of WN- and WC- types with X-rays. Our aim is to detect X-rays from a WO-type binary for the first time, and to compare the X-ray properties (especially the plasma temperature) with those of well-researched two types (WN and WC).

Maeda, Yoshitomo

2009-10-01

125

X-ray spectroscopy and imaging of nike laserproduced plasmas  

Microsoft Academic Search

Plastic foils were irradiated by the NRL Nike KrF laser and were imaged in the x-ray and extreme ultraviolet regions with 2D spatial resolution in the 3–10 ?m range. The CH foils were backlit by a silicon plasma. The silicon backlighter emission was recorded by an x-ray spectrometer, and the Si+12 1,865 eV resonance line emission was recorded by a

J. F. Seely; C. M. Brown; U. Feldman; S. Obenschain; S. Bodner; C. Pawley; K. Gerber; J. Sethian; Y. Aglitskiy; T. Lehecka; G. Holland

1997-01-01

126

SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY  

Microsoft Academic Search

A system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements,

Lincoln J. Miara; L. F. J. Piper; Jacob N. Davis; Laxmikant V. Saraf; Tiffany C. Kaspar; Soumendra Basu; K. E. Smith; Uday B. Pal; Srikanth Gopalan

2010-01-01

127

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

128

Application of confocal X-ray fluorescence micro-spectroscopy to the investigation of paint layers.  

PubMed

A confocal micro X-ray fluorescence (MXRF) spectrometer based on polycapillary X-ray optics was used for the identification of paint layers. The performance of the confocal MXRF was studied. Multilayered paint fragments of a car were analyzed nondestructively to demonstrate that this confocal MXRF instrument could be used in the discrimination of the various layers in multilayer paint systems. PMID:25151613

Sun, Tianxi; Liu, Zhiguo; Wang, Guangfu; Ma, Yongzhong; Peng, Song; Sun, Weiyuan; Li, Fangzuo; Sun, Xuepeng; Ding, Xunliang

2014-12-01

129

Studies of ionic liquid solutions by soft X-ray absorption spectroscopy  

Microsoft Academic Search

Soft X-ray spectroscopies give specific information about the electronic structure around light elements. The high absorption of soft X-rays by almost every molecule, including air, requires studies under vacuum, which represents a great limitation. Solids with high vapor pressure and liquids are very difficult to be studied, making solution chemistry almost neglected. This work explores the use of ionic liquids,

Fabio Rodrigues; Gustavo M. do Nascimento; Paulo S. Santos

2007-01-01

130

Solving the structure of reaction intermediates by time-resolved synchrotron x-ray absorption spectroscopy  

E-print Network

Solving the structure of reaction intermediates by time-resolved synchrotron x-ray absorption present a robust data analysis method of time-resolved x-ray absorption spectroscopy experiments suitable for chemical speciation and structure determination of reaction intermediates. Chemical speciation is done

Frenkel, Anatoly

131

Johann Spectrometer for High Resolution X-ray Spectroscopy  

SciTech Connect

A newly designed vacuum Johann spectrometer with a large focusing analyzer crystal for inelastic x-ray scattering and high resolution fluorescence spectroscopy has been installed at the DORIS III storage ring. Spherically bent crystals with a maximum diameter of 125 mm, and cylindrically bent crystals are employed as dispersive optical elements. Standard radius of curvature of the crystals is 1000 mm, however, the design of the mechanical components also facilitates measurements with smaller and larger bending radii. Up to four crystals are mounted on a revolving crystal changer which enables crystal changes without breaking the vacuum. The spectrometer works at fixed Bragg angle. It is preferably designed for the measurements in non-scanning mode with a broad beam spot, and offers a large flexibility to set the sample to the optimum position inside the Rowland circle. A deep depletion CCD camera is employed as a position sensitive detector to collect the energy-analyzed photons on the circumference of the Rowland circle. The vacuum in the spectrometer tank is typically 10-6 mbar. The sample chamber is separated from the tank either by 25 {mu}m thick Kapton windows, which allows samples to be measured under ambient conditions, or by two gate valves. The spectrometer is currently installed at wiggler beamline W1 whose working range is 4-10.5 keV with typical flux at the sample of 5x1010photons/s/mm2. The capabilities of the spectrometer are illustrated by resonant inelastic experiments on 3d transition metals and rare earth compounds, and by chemical shift measurements on chromium compounds.

Machek, Pavel; Froeba, Michael [Institut fuer Anorganische und Analytische Chemie, Justus-Liebig-Universitaet Giessen, Heinrich-Buff-Ring 58, 35392 Giessen (Germany); Welter, Edmund; Caliebe, Wolfgang; Brueggmann, Ulf [Hamburger Synchrotron Strahlungslabor (HASYLAB) am Deutsches Elektronen Synchrotron (DESY), Notkestrasse 85, 22607 Hamburg (Germany); Draeger, Guenter [Martin-Luther-Universitaet Halle-Wittenberg, Fachbereich Physik, Friedemann-Bach-Platz, 06108 Halle(Saale) (Germany)

2007-01-19

132

Examination of the local structure in composite and lowdimensional semiconductor by X-ray Absorption Spectroscopy  

SciTech Connect

X-ray absorption methods have been successfully used to obtain quantitative information about local atomic composition of two different materials. X-ray Absorption Near Edge Structure analysis and X-Ray Photoelectron Spectroscopy allowed us to determine seven chemical compounds and their concentrations in c-BN composite. Use of Extended X-ray Absorption Fine Structure in combination with Transmission Electron Microscopy enabled us to determine the composition and size of buried Ge quantum dots. It was found that the quantum dots consisted out of pure Ge core covered by 1-2 monolayers of a layer rich in Si.

Lawniczak-Jablonska, K.; Demchenko, I.N.; Piskorska, E.; Wolska,A.; Talik, E.; Zakharov, D.N.; Liliental-Weber, Z.

2006-09-25

133

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

134

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

135

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

136

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

137

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

E-print Network

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 ...

Bitter, M.

138

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

PubMed

A versatile electrochemical in situ reaction cell for long-term hard X-ray experiments on battery electrodes is described. Applications include the small-angle scattering, diffraction and absorption spectroscopy of lithium manganese oxide electrodes. PMID:12824932

Braun, A; Shrout, S; Fowlks, A C; Osaisai, B A; Seifert, S; Granlund, E; Cairns, E J

2003-07-01

139

Quasar spectroscopy in UV and X-ray- probing the intergalactic medium using helium and oxygen  

E-print Network

We employ ultraviolet (UV) and X-ray quasar spectroscopy to study the physical state of the Intergalactic Medium (IGM). First, we quantify the possibility of measuring the temperature of moderately over-dense regions of ...

Gong, Donglai, 1977-

2004-01-01

140

AEGIS: An Astrophysics Experiment for Grating and Imaging Spectroscopy---a Soft X-ray, High-resolution Spectrometer  

NASA Astrophysics Data System (ADS)

AEGIS is a concept for a high-resolution soft X-ray spectroscopic observatory developed in response to NASA's request for definitions of the next X-ray astronomy mission. At a small fraction of the cost of the once-planned International X-ray Observatory (IXO), AEGIS has capabilities that surpass IXO grating spectrometer requirements, and which are far superior to those of existing soft X-ray spectrometers. AEGIS incorporates innovative technology in X-ray optics, diffraction gratings and detectors. The mirror uses high area-to-mass ratio segmented glass architecture developed for IXO, but with smaller aperture and larger graze angles optimized for high-throughput grating spectroscopy with low mass and cost. The unique Critical Angle Transmission gratings combine low mass and relaxed figure and alignment tolerances of Chandra transmission gratings but with high diffraction efficiency and resolving power of blazed reflection gratings. With more than an order of magnitude better performance over Chandra and XMM grating spectrometers, AEGIS can obtain high quality spectra of bright AGN in a few hours rather than 10 days. Such high resolving power allows detailed kinematic studies of galactic outflows, hot gas in galactic haloes, and stellar accretion flows. Absorption line spectroscopy will be used to study large scale structure, cosmic feedback, and growth of black holes in thousands of sources to great distances. AEGIS will enable powerful multi-wavelength investigations, for example with Hubble/COS in the UV to characterize the intergalactic medium. AEGIS will be the first observatory with sufficient resolution below 1 keV to resolve thermally-broadened lines in hot ( 10 MK) plasmas. Here we describe key science investigations enable by Aegis, its scientific payload and mission plan. Acknowledgements: Support was provided in part by: NASA SAO contract SV3-73016 to MIT for the Chandra X-ray Center and Science Instruments; NASA grant NNX08AI62G; and the MKI Instrumentation Development Fund.

Huenemoerder, David; Bautz, M. W.; Davis, J. E.; Heilmann, R. K.; Houck, J. C.; Marshall, H. L.; Neilsen, J.; Nicastro, F.; Nowak, M. A.; Schattenburg, M. L.; Schulz, N. S.; Smith, R. K.; Wolk, S.; AEGIS Team

2012-01-01

141

Analysis of chemical structure of wood charcoal by X-ray photoelectron spectroscopy  

Microsoft Academic Search

Wood charcoal carbonized at various temperatures was analyzed by X-ray photoelectron spectroscopy (XPS), Fourier-transform\\u000a infrared spectroscopy (FTIR), and X-ray diffractometry to investigate the changes of chemical structures during the carbonization\\u000a process. From the infrared spectra, the carbon double bonds and aromatic rings were seen to form at a carbonization temperature\\u000a of about 600°C. From the XPS spectra, the ratio of

Koei Nishimiya; Toshimitsu Hata; Yuji Imamura; Shigehisa Ishihara

1998-01-01

142

X-Ray Crystal Spectroscopy of Subpicosecond Laser-Produced Plasmas beyond 50 keV  

Microsoft Academic Search

The interaction of a sub-picosecond (sub-ps) laser with a high-Ztarget produces a hard x-ray continuum, but to our knowledge no high-resolution study of the line emission is known. We present here crystal spectroscopy as a tool for the observation of energetic line x-radiation from a sub-ps laser-produced plasma. Reflection properties of flat and bent crystals for x-ray spectroscopy are analyzed

G. Hölzer; E. Förster; M. Grätz; C. Tillman; S. Svanberg

1997-01-01

143

Chandra X-ray Imaging and Spectroscopy of the M87 Jet and Nucleus  

E-print Network

We report X-ray imaging - spectroscopy of the jet of M87 at sub arc second resolution with the Chandra X-ray Observatory. The galaxy nucleus and all the knots seen at radio and optical wavelengths, as far from the nucleus as knot C, are detected in the X-ray observations. There is a strong trend for the ratio of X-ray to radio, or optical, flux to decline with increasing distance from the nucleus. At least three knots are displaced from their radio/optical counterparts, being tens of pc closer to the nucleus at X-ray than at radio or optical wavelengths. The X-ray spectra of the nucleus and knots are well described by power laws absorbed by cold gas, with only the unresolved nucleus exhibiting intrinsic absorption. In view of the similar spectra of the nucleus and jet knots, and the high X-ray flux of the knots closest to the nucleus, we suggest that the X-ray emission coincident with the nucleus may actually originate from the pc - or sub-pc - scale jet rather than the accretion disk. Arguments are given that the X-ray emission process is unlikely to be inverse Compton scattering. Instead, we favor synchrotron radiation. Plotted as $\

A. S. Wilson; Y. Yang

2001-12-05

144

X-Ray Spectroscopy of the Liquid Water Surface  

Microsoft Academic Search

We have developed a new experiment for probing molecular details of liquid-vapor interfaces of volatile substances and their solutions under equilibrium conditions. Electronic and geometric structures of interfacial molecules are probed by EXAFS and NEXAFS methods in the soft X-ray region, using the Advanced Light Source, Berkeley, CA. Liquids are introduced into a high vacuum environment through the use of

Richard Saykally

2004-01-01

145

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

146

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. PMID:22919444

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

147

Soft x-ray emission spectroscopy using monochromatized synchrotron radiation (invited)  

NASA Astrophysics Data System (ADS)

Soft x-ray emission spectroscopy is a common tool for the study of the electronic structure of molecules and solids. However, the interpretation of spectra is sometimes made difficult by overlaying lines due to satellite transitions or close-lying core holes. Also, irrelevant inner core transitions may accidentally fall in the wavelength region under study. These problems, which often arise for spectra excited with electrons or broadband photon sources can be removed by using monochromatized synchrotron radiation. In addition, one achieves other advantages as well, such as the ability to study resonant behavior. Another important aspect is the softness of this excitation agent, which allows chemically fragile compounds to be investigated. In this work we demonstrate the feasibility of using monochromatized synchrotron radiation to excite soft x-ray spectra. We also show new results which have been accomplished as a result of the selectivity of the excitation. The work has been carried out using the Flipper I wiggler beamline at HASYLAB in Hamburg using a new grazing incidence instrument designed specifically for this experiment. The photon flux at the Flipper I station (typically 5×1012 photons per second on the sample with a 1% bandpass) is enough to allow soft x-ray fluorescence spectra to be recorded at relatively high resolution and within reasonable accumulation times (typically, the spectra presented in this work were recorded in 30 min). The spectrometer is based on a new concept which allows the instrument to be quite small, still covering a large wavelength range (10-250 Å). The basic idea involves the use of several fixed mounted gratings and a large two-dimensional detector. The grating arrangement provides simple mounting within a limited space and, in particular, large spectral range. The detector can be moved in a three-axis coordinate system in order to cover the different Rowland curves defined by the different gratings. The arrangement permits the use of gratings with different radii, which further facilitate the achievement of optimum performance over a large range. Two-dimensional detection is used to allow a large solid angle, without suffering from loss of resolution due to imaging errors. The detector is based on five 2-in. MCPs with resistive anode read out. The sensitivity of the detector, which is normally very low for soft x rays, especially at grazing angles, is enhanced by CsI coating and by using an entrance electrode.

Nordgren, J.; Bray, G.; Cramm, S.; Nyholm, R.; Rubensson, J.-E.; Wassdahl, N.

1989-07-01

148

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

149

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 Lobstereye 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 ESA AXIOM mission.

Collier, M. R.; Porter, F. S.; Sibeck, D. G.; Carter, J. A.; Chiao, M. P.; Chornay, D. J.; Cravens, T.; Galeazzi, M.; Keller, J. W.; Koutroumpa, D.; Kuntz, K.; Read, A. M.; Robertson, I. P.; Sembay, S.; Snowden, S.; Thomas, N.

2012-01-01

150

Prototyping a global soft X-ray imaging instrument for heliophysics, planetary science, and astrophysics science  

NASA Astrophysics Data System (ADS)

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 ESA AXIOM mission.

Collier, M. R.; Porter, F. S.; Sibeck, D. G.; Carter, J. A.; Chiao, M. P.; Chornay, D. J.; Cravens, T.; Galeazzi, M.; Keller, J. W.; Koutroumpa, D.; Kuntz, K.; Read, A. M.; Robertson, I. P.; Sembay, S.; Snowden, S.; Thomas, N.

2012-04-01

151

A high resolution multipurpose ESCA instrument with X-ray monochromator  

Microsoft Academic Search

The design and performance of a new high resolution multipurpose instrument are described and illustrated. The instrument comprises a high-power, fine-focusing e--gun, a high speed rotating anode, a double focusing multi-crystal X-ray monochromator, a monochromatic UV-source with a toroidal grating, a fine-focus variable energy e--source, a four-element electrostatic e--lens system, a large 36 cm hemispherical electrostatic analyzer, a 12 cm

U. Gelius; L. Asplund; E. Basilier; S. Hedman; K. Helenelund; K. Siegbahn

1984-01-01

152

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

153

WHIMEX: An Explorer for High Resolution X-ray Spectroscopy of the Intergalactic Medium  

NASA Astrophysics Data System (ADS)

With the further deferral of the International X-ray Observatory, there is a need for low cost approaches to high resolution x-ray spectroscopy. WhimEx is a mission concept that will be proposed in response to the current Explorer AO. WhimEx combines the teams and the technology that were being developed for the IXO reflection grating spectrometer. With WhimEx, astronomers will be able to probe the WHIM, AGN outflows and many other classes of x-ray sources in a manner similar to how Copernicus, FUSE and COS have in the ultraviolet.

Cash, Webster C., Jr.; Science, Whimex; Instrument Teams

2011-01-01

154

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

155

RASOR: an advanced instrument for soft x-ray reflectivity and diffraction.  

PubMed

We report the design and construction of a novel soft x-ray diffractometer installed at Diamond Light Source. The beamline endstation RASOR is constructed for general users and designed primarily for the study of single crystal diffraction and thin film reflectivity. The instrument is comprised of a limited three circle (theta, 2theta, and chi) diffractometer with an additional removable rotation (phi) stage. It is equipped with a liquid helium cryostat, and post-scatter polarization analysis. Motorized motions are provided for the precise positioning of the sample onto the diffractometer center of rotation, and for positioning the center of rotation onto the x-ray beam. The functions of the instrument have been tested at Diamond Light Source, and initial test measurements are provided, demonstrating the potential of the instrument. PMID:20687739

Beale, T A W; Hase, T P A; Iida, T; Endo, K; Steadman, P; Marshall, A R; Dhesi, S S; van der Laan, G; Hatton, P D

2010-07-01

156

X-ray scattering and spectroscopy in correlated electron systems  

NASA Astrophysics Data System (ADS)

Resonant x ray scattering is evolving as a very important technique to study the interplay between the atomic structure and the electronic structure of correlated systems like the high Tc superconductors, collossal magneto resistance materials and transition metal compounds in general. The interpretation of the measurements is however far from trivial and reguires approaches which depend strongly on which core levels and valence bands are involved. I will present the basic physics regarding the approximations most suitable for several cases and demonstrate their success with examples from the classes of systems above. It turns out that the transition metal K edge data is not really a direct measure of orbital ordering but rather a measure of the local bond length distortions accompanying the orbital ordering and is well described in density functional band theory. On the other hand soft x ray L edge data is more directly a measure of the orbital as well as spin ordering. These data cannot be described with a band theory approach because of the importance of correlation effects and one must resort to methods like cluster approaches including the strong correlation effects explicitly. In cases where the atom of interest is not at an inversion center new effects in volving dipole and quadrupole channels are important and the experimental studies in these sytems provides direct information on the p-d hybridization in the conduction band. Resonant inelastic scattering in addition provides direct k dependent dispersion relations for a variety of elementary excitations including magnons, phonons and excitons. At soft x ray energies we can expect very strong inelastic scattering for spin flip excitations provided the core state used has a resolved spin orbit coupling.

Sawatzky, George

2002-03-01

157

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

158

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

Microsoft Academic Search

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.

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

2010-01-01

159

X-ray Spectroscopy of Hot Dense Plasmas: Experimental Limits, Line Shifts and Field Effects  

SciTech Connect

High-resolution x-ray spectroscopy is capable of providing complex information on environmental conditions in hot dense plasmas. Benefiting from application of modern spectroscopic methods, we report experiments aiming at identification of different phenomena occurring in laser-produced plasma. Fine features observed in broadened profiles of the emitted x-ray lines and their satellites are interpreted using theoretical models predicting spectra modification under diverse experimental situations.

Renner, Oldrich [Institute of Physics, Academy of Sciences CR, Na Slovance 2, 18221 Prague (Czech Republic); Sauvan, Patrick [Dept. de Ingenieria Energetica-UNED, 28040 Madrid (Spain); Dalimier, Elisabeth; Riconda, Caterina; Rosmej, Frank B. [Physique Atomique dans les Plasmas Denses, LULI, UMR 7605, CNRS-CEA-Ecole Polytechnique- Universite Paris 6, 4 Place Jussieu, 75252 Paris Cedex 05 (France); Weber, Stefan [Physique Atomique dans les Plasmas Denses, LULI, UMR 7605, CNRS-CEA-Ecole Polytechnique- Universite Paris 6, 4 Place Jussieu, 75252 Paris Cedex 05 (France); CELIA Universite Bordeaux-CEA, 33405 Talence (France); Nicolai, Philippe; Peyrusse, Olivier [CELIA Universite Bordeaux-CEA, 33405 Talence (France); Uschmann, Ingo; Hoefer, Sebastian; Kaempfer, Tino; Loetzsch, Robert; Zastrau, Ulf; Foerster, Eckhart [Institut fuer Optik und Quantenelektronik, Friedrich-Schiller-Universitaet, 07743 Jena (Germany); Oks, Eugene [Physics Department, 206 Allison Laboratory, Auburn University, Auburn, AL 36849 (United States)

2008-10-22

160

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

PubMed

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. PMID:24019462

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

2013-09-24

161

Reactive ZnO/Ti/ZnO interfaces studied by hard x-ray photoelectron spectroscopy  

E-print Network

surface sensitive as they use soft x-rays of 1.2­1.5 keV energy, limit- ing the probing depth to a fewReactive ZnO/Ti/ZnO interfaces studied by hard x-ray photoelectron spectroscopy Ronny Knut,1,a Helmholtz-Zentrum Berlin fur Materialien und Energie, Albert-Einstein-Str. 15, D-12489 Berlin, Germany 3

Boyer, Edmond

162

Bulk Sensitive X-Ray Absorption Spectroscopy Free of Self-Absorption Effects  

Microsoft Academic Search

We demonstrate a new method of x-ray absorption spectroscopy (XAS) that is\\u000abulk sensitive, like traditional fluorescence yield measurements, but is not\\u000aaffected by self-absorption or saturation effects. This measure of XAS is\\u000aachieved by scanning the incident photon energy through an absorption edge and\\u000ausing an energy sensitive photon detector to measure the partial fluorescence\\u000ayield (PFY). The x-ray

A. J. Achkar; T. Z. Regier; H. Wadati; Y.-J. Kim; H. Zhang; D. G. Hawthorn

2010-01-01

163

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

164

An X-ray absorption spectroscopy investigation of speciation and biotransformation of copper in Elsholtzia splendens  

Microsoft Academic Search

Elsholtzia splendens is a Cu-tolerant plant growing in copper mine areas in the south of China. In this study, X-ray absorption spectroscopy (XAS)\\u000a was used to investigate the Cu speciation and biotransformation in E. splendens with 300 ?M Cu treatment from 10 days to 60 days. The results showed that 300 ?M Cu was phytotoxic to E. spendens. The Cu K-edge X-ray absorption near

Jiyan Shi; Bei Wu; Xiaofeng Yuan; Cao YY; Xincai Chen; Yingxu Chen; Tiandou Hu

2008-01-01

165

Capturing Transient Electronic and Molecular Structures in Liquids by Picosecond X-Ray Absorption Spectroscopy  

SciTech Connect

We describe an advanced setup for time-resolved x-ray absorption fine structure (XAFS) Spectroscopy with picosecond temporal resolution. It combines an intense femtosecond laser source synchronized to the x-ray pulses delivered into the microXAS beamline of the Swiss Light Source (SLS). The setup is applied to measure the short-lived high-spin geometric structure of photoexcited aqueous Fe(bpy)3 at room temperature.

Gawelda, W. [Laboratoire de Spectroscopie Ultrarapide (LSU), Ecole Polytechnique Federale de Lausanne (EPFL), BSP, CH-1015 Lausanne (Switzerland); Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Pham, V. T.; El Nahhas, A.; Kaiser, M.; Zaushitsyn, Y.; Bressler, C.; Chergui, M. [Laboratoire de Spectroscopie Ultrarapide (LSU), Ecole Polytechnique Federale de Lausanne (EPFL), BSP, CH-1015 Lausanne (Switzerland); Johnson, S. L.; Grolimund, D.; Abela, R. [Swiss Light Source, Paul Scherrer Institut, CH-5232 Villigen-PSI (Switzerland); Hauser, A. [Departement de Chimie Physique, Universite de Geneve, CH-1121 Geneva (Switzerland)

2007-02-02

166

X-ray laser-induced photoelectron spectroscopy for single-state measurements  

Microsoft Academic Search

We demonstrate single-shot x-ray laser-induced time-of-flight photoelectron spectroscopy on metal and semiconductor surfaces with picosecond time resolution. Our compact multipulse terawatt tabletop x-ray laser source provides the necessary high photon flux (>1012?pulse), monochromaticity, picosecond pulse duration, and coherence for probing ultrafast changes in the chemical and electronic structure of these materials. Static valence band and shallow core-level photoemission spectra are

A. J. Nelson; J. Dunn; T. van Buuren

2004-01-01

167

X-ray laser-induced photoelectron spectroscopy for single-state measurements  

Microsoft Academic Search

We demonstrate single-shot x-ray laser-induced time-of-flight photoelectron spectroscopy on metal and semiconductor surfaces with picosecond time resolution. Our compact multipulse terawatt tabletop x-ray laser source provides the necessary high photon flux (>1012\\/pulse), monochromaticity, picosecond pulse duration, and coherence for probing ultrafast changes in the chemical and electronic structure of these materials. Static valence band and shallow core-level photoemission spectra are

A. J. Nelson; J. Dunn; T. van Buuren; J. Hunter

2004-01-01

168

Paraboloidal X-ray telescope mirror for solar coronal spectroscopy  

NASA Technical Reports Server (NTRS)

The telescope mirror for the X-ray Spectrograph Spectrometer Telescope System is a sixty degree sector of an extreme off-axis paraboloid of revolution. It was designed to focus a coronal region 1 by 10 arc seconds in size on the entrance slit of the spectrometer after reflection from the gold surface. This paper discusses the design, manufacture, and metrology of the mirror, the methods of precision mechanical metrology used to focus the system, and the mounting system which locates the mirror and has proven itself through vibration tests. In addition, the results of reflection efficiency measurements, alignment tolerances, and ray trace analysis of the effects of misalignment are considered.

Brown, W. A.; Bruner, E. C., Jr.; Acton, L. W.; Franks, A.; Stedman, M.; Speer, R. J.

1979-01-01

169

Hard x-ray spectroscopy of NIF targets  

NASA Astrophysics Data System (ADS)

A hard x-ray spectrometer with five channels covering the energy range 1.1-20.1 keV is planned for the study of plasmas produced at the NIF and OMEGA laser facilities. The spectrometer utilizes four crystals in reflection, with a geometry similar to the NOVA HENWAY spectrometer, and one crystal in transmission. Spectra are recorded on CCD detectors with resolving power in the range 315-2800. A related single channel spectrometer, utilizing one transmission crystal and covering 12-60 keV, is presently under construction for the OMEGA laser.

Seely, John; Holland, Glenn; Deslattes, Richard; Hudson, Lawrence; Bell, Perry; Back, Christina; Miller, Michael

2000-11-01

170

X-ray spectroscopy of the SSME plume  

NASA Technical Reports Server (NTRS)

In order to examine the potential of using SSME exhaust plume radiation in the soft X-ray spectrum as an early warning system of imminent engine failure, a low cost, low risk experiment was devised. An approach was established, equipment was leased, the system was installed and checked out, and data were successfully acquired demonstrating the proof-of-concept. One spectrum measurement of the SSME plume was acquired during a 300 second burn on the A-1 Test Stand. This spectrum showed a prominent, line emission feature at about 34.5 KeV, a result which was not expected, nor can it be explained at this time. If X-ray spectra are to be useful as a means of monitoring nominal engine operation, it will be necessary to explore this region of the EM spectrum in greater detail. The presence of structure in the spectrum indicates that this technology may prove to be useful as an engine health monitoring system.

Olive, Dan F.

1988-01-01

171

Applications of X-ray absorption spectroscopy to biologically relevant metal-based chemistry  

NASA Astrophysics Data System (ADS)

Recent developments in the understanding of the biosynthesis of the active site of the nitrogenase enzyme, the structure of the iron centre of [Fe]-hydrogenase and the structure and biomimetic chemistry of the [FeFe] hydrogenase H-cluster as deduced by application of X-ray spectroscopy are reviewed. The techniques central to this work include X-ray absorption spectroscopy either in the form of extended X-ray absorption fine structure (EXAFS), X-ray absorption near-edge structure (XANES) and nuclear resonant vibrational spectroscopy (NRVS). Examples of the advances in the understanding of the chemistry of the system through integration of a range of spectroscopic and computational techniques with X-ray spectroscopy are highlighted. The critical role played by ab initio calculation of structural and spectroscopic properties of transition-metal compounds using density functional theory (DFT) is illustrated both by the calculation of nuclear resonance vibrational spectroscopy (NRVS) spectra and the structures and spectra of intermediates through the catalytic reactions of hydrogenase model compounds.

Best, Stephen P.; Cheah, Mun Hon

2010-02-01

172

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

SciTech Connect

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

Sun, Cheng-Jun, E-mail: cjsun@aps.anl.gov; Brewe, Dale L.; Heald, Steve M. [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States)] [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Zhang, Bangmin [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States) [Advanced Photon Source, Argonne National Laboratory, Argonne, Illinois 60439 (United States); Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore (Singapore); NUSNNI-Nanocore, National University of Singapore, 117411 Singapore (Singapore); Chen, Jing-Sheng; Chow, G. M. [Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore (Singapore)] [Department of Materials Science and Engineering, National University of Singapore, 117575 Singapore (Singapore); Venkatesan, T. [NUSNNI-Nanocore, National University of Singapore, 117411 Singapore (Singapore) [NUSNNI-Nanocore, National University of Singapore, 117411 Singapore (Singapore); Department of Physics, National University of Singapore, 117542 Singapore (Singapore); Department of Electrical and Computer Engineering, National University of Singapore, 117575 Singapore (Singapore)

2014-04-15

173

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

174

X-ray Photoelectron Spectroscopy and Kinetic Study: Pt-Group Metals and Bimetallic Surfaces  

E-print Network

as shown in Figure 1. The analysis section houses a hemispherical analyzer, X-ray source with Mg and Al anodes, Auger gun, differentially pumped ion gun, monochromator, external light source, ion pump, and titanium sublimation pump. The preparation... ....................................... 15 Auger Electron Spectroscopy ................................................. 16 Low Energy Ion Scattering Spectroscopy (LEISS) ................ 19 Gas Chromatography (GC)..................................................... 20...

Gath, Kerrie K.

2010-01-14

175

X-ray Spectroscopy for Quality Control of Chemotherapy Drugs  

SciTech Connect

We develop a method, employing Compton peak standardization and the use of matrix-matched spiked samples with Total Reflection X-ray Fluorescence (TXRF), for the determination of platinum plasma concentrations of patients undergoing chemotherapy with Pt-bearing drugs. Direct blood plasma analysis attains Pt detection limits of 70 ng/ml. Measurement results of prescribed drug doses are compared to achieved blood Pt concentrations indicating a lack of expected correlations. Direct analysis of Pt-containing infused drugs from a variety of suppliers indicates cases of abnormal concentrations which raises quality control issues. We demonstrate the potential usefulness of the method for pharmacokinetic studies or for routine optimization and quality control of Pt chemotherapy treatments.

Greaves, E. D.; Barros, H.; Bermudez, J.; Sajo-Bohus, L. [Universidad Simon Bolivar, Apartado 89000, Caracas 1080A (Venezuela); Angeli-Greaves, M. [Universidad Central de Venezuela, Apartado 90373 Caracas 1083A (Venezuela)

2007-10-26

176

X ray spectroscopy of highly charged ions interacting with surfaces  

SciTech Connect

The interaction of highly charged ions on surfaces has been studied at various incidence angles by looking at the X rays emitted in flight by the ions with a crystal spectrometer. This paper is focused on the study of the decay between the L and K shell which is mainly an Auger process for highly charged ions like Ar[sup 17+]. A model has been developed to describe the behaviour of the ions outside the surface,a nd Dirac-Fock calculations of the Auger rates for states with many electrons in high n states have been performed. The formation of highly excited hollow atoms, outside the surface, has been observed, at grazing incidence. The signature of these superexcited ions only represents a few % of the overall observed decays.

d'Etat, B. (Laboratorie de Physique Atomique et Nucleaire, Institut du Radium, Boite 93, Universite P M Cuire, 4 place Jussieu, F-57252 Paris Cedex 05 (France)); Briand, J.P.; Ban, G.; de Billy, L. (Laboratoire de Physique Atomique et Nucleaire, Institut du Radium Boite 93, Universite P M Curie, 4 place Jussieu, F-75252 Paris Cedex 05 (France)); Briand, P.; Desclaux, J.P.; Melin, G. (Department de Recherche Fondamentale de la Matiere Condensee,Centre d'Etudes Nucleaires de Grenoble, Grenoble Cedex (France)); Lamy, T.; Lamboley, G. (LAGRIPPA, Centre d'Etudes Nucleaires de Grenoble, 85X, 3804, Grenoble Cedex (France)); Richard, P.; Stockli, M.; Ali, R.; Renard, N. (J. R.,Macdonld Laboratory, Kansas State University, Manhattan, KS (United States)); Schneider, D.; Clark, M.; Beiersdorfer, P.; Decaux, V. (High Temperature Physics Division, Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, CA 94550 (United States))

1993-06-05

177

Polychromatic X-ray Micro- and Nano-Beam Science and Instrumentation  

SciTech Connect

Polychromatic x-ray micro- and nano-beam diffraction is an emerging nondestructive tool for the study of local crystalline structure and defect distributions. Both long-standing fundamental materials science issues, and technologically important questions about specific materials systems can be uniquely addressed. Spatial resolution is determined by the beam size at the sample and by a knife-edge technique called differential aperture microscopy that decodes the origin of scattering from along the penetrating x-ray beam. First-generation instrumentation on station 34-ID-E at the Advanced Photon Source (APS) allows for nondestructive automated recovery of the three-dimensional (3D) local crystal phase and orientation. Also recovered are the local elastic-strain and the dislocation tensor distributions. New instrumentation now under development will further extend the applications of polychromatic microdiffraction and will revolutionize materials characterization.

Ice, G. E.; Larson, B. C.; Liu, W.; Barabash, R. I.; Specht, E. D.; Pang, J. W. L.; Budai, J. D.; Tischler, J. Z. [Materials Science and Technology Division, Oak Ridge National Laboratory, Oak Ridge TN 37831-6118 (United States); Khounsary, A.; Liu, C.; Macrander, A. T.; Assoufid, L. [Advanced Photon Source, Argonne National Laboratory, 9700 S. Cass Ave. Argonne Il 60439 (United States)

2007-01-19

178

Polychromatic X-ray Micro- and Nano-Beam Science and Instrumentation  

SciTech Connect

Polychromatic x-ray micro- and nano-beam diffraction is an emerging nondestructive tool for the study of local crystalline structure and defect distributions. Both long-standing fundamental materials science issues, and technologically important questions about specific materials systems can be uniquely addressed. Spatial resolution is determined by the beam size at the sample and by a knife-edge technique called differential aperture microscopy that decodes the origin of scattering from along the penetrating x-ray beam. First-generation instrumentation on station 34-ID-E at the Advanced Photon Source (APS) allows for nondestructive automated recovery of the three-dimensional (3D) local crystal phase and orientation. Also recovered are the local elastic-strain and the dislocation tensor distributions. New instrumentation now under development will further extend the applications of polychromatic microdiffraction and will revolutionize materials characterization.

Ice, Gene E [ORNL; Larson, Ben C [ORNL; Liu, Wenjun [ORNL; Barabash, Rozaliya [ORNL; Specht, Eliot D [ORNL; Pang, Judy [ORNL; Budai, John D [ORNL; Tischler, Jonathan Zachary [ORNL; Khounsary, Ali [Argonne National Laboratory (ANL); Liu, Chian [Argonne National Laboratory (ANL); Macrander, Albert T. [Argonne National Laboratory (ANL); Assoufid, Lahsen [Argonne National Laboratory (ANL)

2007-01-01

179

Development of a hard X-ray delay line for X-ray photon correlation spectroscopy and jitter-free pump–probe experiments at X-ray free-electron laser sources  

PubMed Central

A hard X-ray delay line capable of splitting and delaying single X-ray pulses has been developed with the aim of performing X-ray photon correlation spectroscopy (XPCS) and X-ray pump–probe experiments at hard X-ray free-electron laser sources. The performance of the device was tested with 8.39?keV synchrotron radiation. Time delays up to 2.95?ns have been demonstrated. The feasibility of the device for performing XPCS studies was tested by recording static speckle patterns. The achieved speckle contrast of 56% indicates the possibility of performing ultra-fast XPCS studies with the delay line. PMID:21525658

Roseker, Wojciech; Franz, Hermann; Schulte-Schrepping, Horst; Ehnes, Anita; Leupold, Olaf; Zontone, Federico; Lee, Sooheyong; Robert, Aymeric; Grübel, Gerhard

2011-01-01

180

High-Resolution Structure of the Photosynthetic Mn4Ca Catalyst From X-Ray Spectroscopy  

SciTech Connect

The application of high-resolution X-ray spectroscopy methods to study the photosynthetic water oxidizing complex, which contains a unique hetero-nuclear catalytic Mn{sub 4}Ca cluster, is described. Issues of X-ray damage, especially at the metal sites in the Mn{sub 4}Ca cluster, are discussed. The structure of the Mn{sub 4}Ca catalyst at high resolution, which has so far eluded attempts of determination by X-ray diffraction, X-ray absorption fine structure (EXAFS) and other spectroscopic techniques, has been addressed using polarized EXAFS techniques applied to oriented photosystem II (PSII) membrane preparations and PSII single crystals. A review of how the resolution of traditional EXAFS techniques can be improved, using methods such as range-extended EXAFS, is presented, and the changes that occur in the structure of the cluster as it advances through the catalytic cycle are described. X-ray absorption and emission techniques (XANES and K{beta} emission) have been used earlier to determine the oxidation states of the Mn{sub 4}Ca cluster, and in this report we review the use of X-ray resonant Raman spectroscopy to understand the electronic structure of the Mn{sub 4}Ca cluster as it cycles through the intermediate S-states.

Yano, J.; Kern, J.; Pushkar, Y.; Sauer, K.; Glatzel, P.; Bergmann, U.; Messinger, J.; Zouni, A.; Yachandra, V.K.; /LBL, Berkeley /ESRF, Grenoble /SLAC, SSRL /Max Planck Inst., Mulheim

2009-04-30

181

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

182

Picosecond and femtosecond X-ray absorption spectroscopy of molecular systems.  

PubMed

The need to visualize molecular structure in the course of a chemical reaction, a phase transformation or a biological function has been a dream of scientists for decades. The development of time-resolved X-ray and electron-based methods is making this true. X-ray absorption spectroscopy is ideal for the study of structural dynamics in liquids, because it can be implemented in amorphous media. Furthermore, it is chemically selective. Using X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) in laser pump/X-ray probe experiments allows the retrieval of the local geometric structure of the system under study, but also the underlying photoinduced electronic structure changes that drive the structural dynamics. Recent developments in picosecond and femtosecond X-ray absorption spectroscopy applied to molecular systems in solution are reviewed: examples on ultrafast photoinduced processes such as intramolecular electron transfer, low-to-high spin change, and bond formation are presented. PMID:20164646

Chergui, Majed

2010-03-01

183

X-ray photoemission and energy dispersive spectroscopy of hydroxyapatite-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 photoemission) and bulk analysis (energy dispersive spectroscopy). The specimens examined were controls and specimens aged 30 min and 3 h at room temperature in distilled water and 0.2M sodium phosphate buffer (pH 7.2). Each X-ray photoemission cycle consisted of three scans followed by argon sputtering for 10 min for usually 20 cycles, corresponding to a sampling depth of {approximately}1,500 {angstrom}. The energy dispersive spectroscopy analysis was on a 110 by 90 {micro}m area for 500 s. The X-ray photoemission 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 phosphorus. No differences in the chemical composition were observed by energy dispersive spectroscopy analysis.

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

1997-07-01

184

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

185

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

186

X-Ray Diffraction Techniques for a Field Instrument: Patterns of Lithologic Provences  

NASA Technical Reports Server (NTRS)

Future exploration of Mars will attempt to shed light on the mineralogy of surface materials. Instruments deployed from remote platforms should have the capability to conduct both intensive analyses as well as rapid, reconnaissance surveys while they function in the martian environment as surrogate geologists. In order to accommodate the reconnaissance mode of analysis and to compensate for analytical limitations imposed by the space-flight conditions, data analysis methods are being developed that will permit interpretation of data by recognition of signatures or "fingerprints". Specifically, we are developing a technique which will allow interpretation of diffraction patterns by recognition of characteristic signatures of different lithologic provences. This technique allows a remote vehicle to function in a rapid-scan mode using the lithologic signature to determine where a more thorough analysis is needed. An x-ray diffraction pattern is characterized by the angular positions of diffracted x-rays, x-ray intensity levels and background radiation levels. These elements may be used to identify a generalized x-ray signature. Lithologic signatures are being developed in two ways. A signature is composed using the ideal powder diffraction indices from the mineral assembledge common to a specific lithologic provence. This is then confirmed using a laboratory diffraction pattern of a whole rock powder. Preliminary results comparing the diffraction signatures of the major mineral assembledges common to basalt, carbonate, and evaporite basin deposits indicate that lithologies are differentiable as a "fingerprint". Statistical analyses are being performed to establish the confidence levels of this technique.

Marshall, J.; Keaten, R.

1999-01-01

187

In situ anodization of aluminum surfaces studied by x-ray reflectivity and electrochemical impedance spectroscopy  

NASA Astrophysics Data System (ADS)

We present results from the anodization of an aluminum single crystal [Al(111)] and an aluminum alloy [Al 6060] studied by in situ x-ray reflectivity, in situ electrochemical impedance spectroscopy and ex situ scanning electron microscopy. For both samples, a linear increase of oxide film thickness with increasing anodization voltage was found. However, the slope is much higher in the single crystal case, and the break-up of the oxide film grown on the alloy occurs at a lower anodization potential than on the single crystal. The reasons for these observations are discussed as are the measured differences observed for x-ray reflectivity and electrochemical impedance spectroscopy.

Bertram, F.; Zhang, F.; Evertsson, J.; Carlà, F.; Pan, J.; Messing, M. E.; Mikkelsen, A.; Nilsson, J.-O.; Lundgren, E.

2014-07-01

188

CdZnTe detector in mammographic x-ray spectroscopy.  

PubMed

A CdZnTe (CZT) detector was utilized in mammographic x-ray spectroscopy under clinical conditions. First, the detector response was investigated using y-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. PMID:12476976

Miyajima, Satoshi; Imagawa, Kotaro

2002-11-21

189

FORTRAN program for x ray photoelectron spectroscopy data reformatting  

NASA Astrophysics Data System (ADS)

A FORTRAN program has been written for use on an IBM PC/XT or AT or compatible microcomputer (personal computer, PC) that converts a column of ASCII-format numbers into a binary-format file suitable for interactive analysis on a Digital Equipment Corporation (DEC) computer running the VGS-5000 Enhanced Data Processing (EDP) software package. The incompatible floating-point number representations of the two computers were compared, and a subroutine was created to correctly store floating-point numbers on the IBM PC, which can be directly read by the DEC computer. Any file transfer protocol having provision for binary data can be used to transmit the resulting file from the PC to the DEC machine. The data file header required by the EDP programs for an x ray photoelectron spectrum is also written to the file. The user is prompted for the relevant experimental parameters, which are then properly coded into the format used internally by all of the VGS-5000 series EDP packages.

Abel, Phillip B.

1989-11-01

190

Mode-Locked Multichromatic X-Rays in a Seeded Free-Electron Laser for Single-Shot X-Ray Spectroscopy  

SciTech Connect

We present the promise of generating gigawatt mode-locked multichromatic x rays in a seeded free-electron laser (FEL). We show that, by using a laser to imprint periodic modulation in electron beam phase space, a single-frequency coherent seed can be amplified and further translated to a mode-locked multichromatic output in an FEL. With this configuration the FEL output consists of a train of mode-locked ultrashort pulses which span a wide frequency gap with a series of equally spaced sharp lines. These gigawatt multichromatic x rays may potentially allow one to explore the structure and dynamics of a large number of atomic states simultaneously. The feasibility of generating mode-locked x rays ranging from carbon K edge ({approx}284 eV) to copper L{sub 3} edge ({approx}931 eV) is confirmed with numerical simulation using the realistic parameters of the linac coherent light source (LCLS) and LCLS-II. We anticipate that the mode-locked multichromatic x rays in FELs may open up new opportunities in x-ray spectroscopy (i.e. resonant inelastic x-ray scattering, time-resolved scattering and spectroscopy, etc.).

Xiang, Dao; Ding, Yuantao; Raubenheimer, Tor; Wu, Juhao; /SLAC

2012-05-10

191

Multidimensional x-ray spectroscopy of valence and core excitations in cysteine  

NASA Astrophysics Data System (ADS)

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 {k}_I =-{k} _1+{k} _2+{k} _3 and {k}_II ={k} _1-{k} _2+{k} _3 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

2013-04-01

192

An alpha particle instrument with alpha, proton, and X-ray modes for planetary chemical analyses  

NASA Technical Reports Server (NTRS)

The interaction of alpha particles with matter is employed in a compact instrument that could provide rather complete in-situ chemical analyses of surfaces and thin atmospheres of extraterrestrial bodies. The instrument is a miniaturized and improved version of the Surveyor lunar instrument. The backscattering of alpha particles and (alpha, p) reactions provide analytical data on the light elements (carbon-iron). An X-ray mode that detects the photons produced by the alpha sources provides sensitivity and resolution for the chemical elements heavier than about silicon. The X-rays are detected by semiconductor detectors having a resolution between 150 and 250 eV at 5.9 keV. Such an instrument can identify and determine with good accuracy 99 percent of the atoms (except hydrogen) in rocks. For many trace elements, the detecting sensitivity is a few ppm. Auxiliary sources could be used to enhance the sensitivities for elements of special interest. The instrument could probably withstand the acceleration involved in semi-hard landings.

Economou, T. E.; Turkevich, A. L.

1976-01-01

193

X-ray temperature spectroscopy of simulated cooling clusters  

E-print Network

Results from a large sample of hydrodynamical/N-body simulations of galaxy clusters in a LCDM cosmology are used to simulate cluster X-ray observations as expected from Chandra observations. The physical modeling of the gas includes radiative cooling, star formation, energy feedback and metal enrichment. The biasing of spectral temperatures with respect to mass-weighted temperatures is found to be influenced by two independent processes. The first scale dependency is absent in adiabatic runs and is due to cooling, whose efficiency to transform cold gas into stars is higher for cool clusters and this in turn implies a strong dependency of the spectral versus mass-weighted temperature relation on the cluster mass. The second dependency is due to photon emission because of cool gas which is accreted during merging events and biases the spectral fits. These events have been quantified according to the power ratio method and a robust correlation is found to exist between the spectral bias and the amount of cluster substructure. The shape of the simulated temperature profiles is not universal and it is steeper at the cluster center for cool clusters than for the massive ones. The profiles are in good agreement with data in the radial range between $\\sim 0.1 r_{vir}$ and $\\sim 0.4 r_{vir}$; at small radii ($r< 0.1 r_{vir}$) the cooling runs fail to reproduce the shape of the observed profiles. The fit is improved if one considers a hierarchical merging scenario in which cluster cores can accrete cooler gas through merging with cluster subclumps, though the shape of the temperature profiles is modified in a significant way only in the regime where the mass of the substructure is a large fraction of the cluster mass.

R. Valdarnini

2006-08-17

194

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

195

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

196

Spatially resolved high resolution x-ray spectroscopy for magnetically confined fusion plasmas (invited)  

SciTech Connect

The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage of a new x-ray imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in x-ray detector technology [Ch. Broennimann et al., J. Synchrotron Radiat. 13, 120 (2006)], a spatially resolving high resolution x-ray spectrometer has been built and installed on the Alcator C-Mod tokamak. This instrument utilizes a spherically bent quartz crystal and a set of two dimensional x-ray detectors arranged in the Johann configuration [H. H. Johann, Z. Phys. 69, 185 (1931)] to image the entire plasma cross section with a spatial resolution of about 1 cm. The spectrometer was designed to measure line emission from H-like and He-like argon in the wavelength range 3.7 and 4.0 A with a resolving power of approximately 10 000 at frame rates up to 200 Hz. Using spectral tomographic techniques [I. Condrea, Phys. Plasmas 11, 2427 (2004)] the line integrated spectra can be inverted to infer profiles of impurity emissivity, velocity, and temperature. From these quantities it is then possible to calculate impurity density and electron temperature profiles. An overview of the instrument, analysis techniques, and example profiles are presented.

Ince-Cushman, A.; Rice, J. E.; Reinke, M. L.; Podpaly, Y.; Marmar, E. S. [Massachusetts Institute of Technology, Cambridge, Massachusetts 02139 (United States); Bitter, M.; Hill, K. W.; Scott, S. [Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543 (United States); Gu, M. F. [Lawrence Livermore National Laboratory, California 94550 (United States); Eikenberry, E.; Broennimann, Ch. [DECTRIS Ltd., Villigen-PSI 5232 (Switzerland); Lee, S. G. [National Fusion Research Institute, Yusung, Taejeon 305-333 (Korea, Republic of)

2008-10-15

197

Spatially resolved high resolution x-ray spectroscopy for magnetically confined fusion plasmas (invited).  

PubMed

The use of high resolution x-ray crystal spectrometers to diagnose fusion plasmas has been limited by the poor spatial localization associated with chord integrated measurements. Taking advantage of a new x-ray imaging spectrometer concept [M. Bitter et al., Rev. Sci. Instrum. 75, 3660 (2004)], and improvements in x-ray detector technology [Ch. Broennimann et al., J. Synchrotron Radiat. 13, 120 (2006)], a spatially resolving high resolution x-ray spectrometer has been built and installed on the Alcator C-Mod tokamak. This instrument utilizes a spherically bent quartz crystal and a set of two dimensional x-ray detectors arranged in the Johann configuration [H. H. Johann, Z. Phys. 69, 185 (1931)] to image the entire plasma cross section with a spatial resolution of about 1 cm. The spectrometer was designed to measure line emission from H-like and He-like argon in the wavelength range 3.7 and 4.0 A with a resolving power of approximately 10,000 at frame rates up to 200 Hz. Using spectral tomographic techniques [I. Condrea, Phys. Plasmas 11, 2427 (2004)] the line integrated spectra can be inverted to infer profiles of impurity emissivity, velocity, and temperature. From these quantities it is then possible to calculate impurity density and electron temperature profiles. An overview of the instrument, analysis techniques, and example profiles are presented. PMID:19044464

Ince-Cushman, A; Rice, J E; Bitter, M; Reinke, M L; Hill, K W; Gu, M F; Eikenberry, E; Broennimann, Ch; Scott, S; Podpaly, Y; Lee, S G; Marmar, E S

2008-10-01

198

X-Ray Absorption Spectroscopy of Strontium(II) Coordination.  

PubMed

Detailed analyses of crystalline, hydrated, and precipitated strontium compounds and an aqueous strontium solution by synchrotron extended X-ray absorption fine structure (EXAFS) were used to quantify local thermal and static disorder and to characterize strontium coordination in a variety of oxygen-ligated bonding environments. Analysis of anharmonic vibrational disorder (i.e., significant contribution from a third cumulant term (C(3)) in the EXAFS phase-shift function) in compounds with low and high static disorder around strontium showed that first-shell anharmonic contributions were generally not significant above experimental error in the EXAFS fits (R+/-0.02 Å with and without C(3)). The only case in which a significant apparent decrease in Sr-O distance was observed with increasing temperature, and for which a third cumulant term was significant, was for dilute strontium in aqueous solution. Empirical parameterization of Debye-Waller factor (sigma(2)) for strontium compounds as a function of backscatterer atomic number (Z), interatomic Sr-Z distance, and temperature of spectral data collection showed systematic increases in sigma(2) as a function of increasing temperature and Sr-Z bond length. At values of sigma(2) greater than approximately 0.025 Å(2) (for N<12 and R(Sr)-Z>3 Å), backscattering was generally not significant above noise levels in spectra of compounds of known crystal structure. Comparison of the EXAFS spectra of freshly precipitated SrCO(3) (spectra collected wet) to that of dry, powdered strontianite (SrCO(3)(s)) indicated no significant differences in the local atomic structure around strontium. Analysis of partially hydrated strontium in natural Ca-zeolite (heulandite) showed that strontium is substituted only in the calcium (Ca2) site. Backscattering from aluminum and silicon atoms in the zeolite framework were apparent in the EXAFS spectra at low and room temperature at distances from central strontium of <4.2 Å. Comparison of strontium structural coordination determined in this and previous studies suggests that previous EXAFS determinations of hydrated strontium may have underestimated first-shell interatomic distances and coordination numbers because minor contributions to the EXAFS phase-shift and amplitude functions were not accounted for, either theoretically or empirically. Copyright 2000 Academic Press. PMID:10662514

O'Day; Newville; Neuhoff; Sahai; Carroll

2000-02-15

199

X-Ray Diffraction and Fluorescence Measurements for In Situ Planetary Instruments  

NASA Astrophysics Data System (ADS)

The ESA/NASA ExoMars mission, due for launch in 2018, has a combined X-ray fluorescence/diffraction instrument, Mars-XRD, as part of the onboard analytical laboratory. The results of some XRF (X-ray fluorescence) and XRD (X-ray diffraction) tests using a laboratory chamber with representative performance are reported. A range of standard geological reference materials and analogues were used in these tests. The XRD instruments are core components of the forthcoming NASA Mars Science Laboratory (MSL) and ESA/NASA ExoMars missions and will provide the first demonstrations of the capabilities of combined XRD/XRF instrumentation in situ on an extraterrestrial planetary surface. The University of Leicester team is part of the Italy-UK collaboration that is responsible for building the ExoMars X-ray diffraction instrument, Mars-XRD [1,2]. Mars-XRD incorporates an Fe-55 radioisotope source and three fixed-position charge-coupled devices (CCDs) to simultaneously acquire an X-ray fluorescence spectrum and a diffraction pattern providing a measurement of both elemental and mineralogical composition. The CCDs cover an angular range of 2? = 6° to 73° enabling the analysis of a wide range of geologically important minerals including phyllosilicates, feldspars, oxides, carbonates and evaporites. The identification of hydrous minerals may help identify past Martian hydrothermal systems capable of preserving traces of life. Here we present some initial findings from XRF and XRD tests carried out at the University of Leicester using an Fe-55 source and X-ray sensitive CCD. The XRF/XRD test system consists of a single CCD on a motorised arm, an Fe-55 X-ray source, a collimator and a sample table which approximately replicate the reflection geometry of the Mars-XRD instrument. It was used to test geological reference standard materials and Martian analogues. This work was funded by the Science and Technology Facilities Council, UK. References [1] Marinangeli, L., Hutchinson, I., Baliva, A., Stevoli, A., Ambrosi, R., Critani, F., Delhez, R., Scandelli, L., Holland, A., Nelms, N. & the Mars-XRD Team, Proceedings of the 38th Lunar and Planetary Science Conference, 12 - 16 March 2007, League City, Texas, USA. [2] L. Marinangeli, I. B. Hutchinson, A. Stevoli, G. Adami, R. Ambrosi, R. Amils, V. Assis Fernandes, A. Baliva, A. T. Basilevsky, G. Benedix, P. Bland, A. J. Böttger, J. Bridges, G. Caprarelli, G. Cressey, F. Critani, N. d'Alessandro, R. Delhez, C. Domeneghetti, D. Fernandez-Remolar, R. Filippone, A. M. Fioretti, J. M. Garcia Ruiz, M. Gilmore, G. M. Hansford, G. Iezzi, R. Ingley, M. Ivanov, G. Marseguerra, L. Moroz, C. Pelliciari, P. Petrinca, E. Piluso, L. Pompilio, J. Sykes, F. Westall and the MARS-XRD Team, EPSC-DPS Joint Meeting 2011, 3 - 7 October 2011, La Cité Internationale des Congrès Nantes Métropole, Nantes, France.

Hansford, G.; Hill, K. S.; Talboys, D.; Vernon, D.; Ambrosi, R.; Bridges, J.; Hutchinson, I.; Marinangeli, L.

2011-12-01

200

Multi-angular regolith effects on planetary soft X-ray fluorescence spectroscopy  

NASA Astrophysics Data System (ADS)

Fluorescent X-rays from the surfaces of airless planetary bodies in the inner solar system have been measured by instruments on several spacecraft. MESSENGER carries an X-ray spectrometer (XRS) on-board and has already attempted to obtain fluorescent X-rays from the Hermean surface. BepiColombo will later on carry an X-ray telescope (MIXS-T) along with a more conventional collimating detector (MIXS-C) to the Hermean orbit, supported by a next-generation X-ray solar monitor (SIXS). These instruments will provide unprecedented knowledge about the geochemical properties of the Hermean regolith. X-ray emission from planetary surfaces follows photoionisation by incident solar X-rays and charged particles and reveals information about the elemental composition of the surface. Analyses of X-ray spectra, obtained by orbiting spacecraft, use both the relative intensities of elemental emission lines (e.g., Ca/Si, Fe/Si) and absolute abundancies of the elements to determine the geochemistry of the target body. Historically, the analysis of X-ray spectra has largely assumed that surfaces can be considered as homogeneous plane-parallel media. It has been shown, however, that fluorescent line intensities are affected by the physical properties of the target surface (e.g., surface roughness of the regolith) as a function of the viewing and illumination geometry of observations in a way that cannot be explained by the traditional models. We describe experimental investigations where we simulated the effects of regolith properties on the fluorescent lines measured by an orbiting instrument, with a large variety of illumination and viewing angles. The planetary regolith analogue used in these experiments was a terrestrial, olivine rich basalt, which has been used by previous authors as an analogue to the lunar maria. The basalt samples were ground to powder and sieved to discriminate particles in the ranges, <75 micrometers, 75-250 micrometers, and 250-500 micrometers. These separate powders were then pressed into solid pellets. The separation of particles with different sizes allows some determination of the effects due to changes in, e.g., surface roughness. The pellets were imaged with a CT scanner to obtain the physical parameters of the samples. All measurements were made at near-vacuum pressures to prevent absorption of fluorescent X-rays in air. The relative fluorescent line ratios of several major rock-forming elements (e.g., Si, K, Ca, Ti, Fe) were measured. In addition to experimental studies we have simulated the X-ray emission from a regolith using a numerical Monte-Carlo ray-tracing model. This model simulates a regolith of spherical particles, with defined physical properties (particle size distribution, packing density, etc.) and with a realistic macro-scale surface roughness characteristics generated by constraining the surface with a fractional-Brownian-motion surface model. A comparison is made between the modelling and experimental results to validate the modelling. A good agreement between the results is found. We find that both the measured and the simulated spectra become increasingly hard as the phase angle increases (i.e., X-ray lines at higher energies are enhanced relative to those at lower energies). Some hardening of spectra is predicted by the fundamental parameters equation (FPE) of X-ray fluorescence, which assumes a smooth, flat, and homogeneous surface, but we observe further spectral hardening that is in excess to that predicted by the FPE and that this excess hardening is also a function of the surface roughness. We propose to use modelling similar to ours for the data analysis of soft X-ray fluorescence spectra to take the multi-angular effects related to the physical properties of the regolith into account.

Näränen, J.; Parviainen, H.; Carpenter, J.; Muinonen, K.

2009-04-01

201

X-ray Absorption Spectroscopy Study of the Effects of pH and Ionic  

E-print Network

X-ray Absorption Spectroscopy Study of the Effects of pH and Ionic Strength on Pb(II) Sorption SiO2 was studied as a function of pH and ionic strength using XAS to characterize the sorption products formed. Pb sorption increased with increasing pH and decreasing ionic strength. The XAS data

Sparks, Donald L.

202

Status of the X-Ray Absorption Spectroscopy (XAS) Beamline at the Australian Synchrotron  

SciTech Connect

We present herein the current status of the X-ray Absorption Spectroscopy (XAS) Beamline at the 3 GeV Australian Synchrotron. The optical design and performance, details of the insertion device (Wiggler), end station capabilities and construction and commissioning timeline are given.

Glover, C.; McKinlay, J.; Clift, M.; Barg, B.; Boldeman, J.; Broadbent, A. [Australian Synchrotron Project, Clayton (Australia); Ridgway, M. [Australian National University, Canberra (Australia); Foran, G.; Garret, R. [Australian Nuclear Science and Technology Organisation, Menai (Australia); Lay, P. [University of Sydney, Sydney (Australia)

2007-02-02

203

Oxidation of plutonium dioxide: an X-ray absorption spectroscopy study  

Microsoft Academic Search

X-ray absorption spectroscopy experiments were conducted in order to characterise plutonium dioxide oxidation. It is shown that the sample preparation adopted does not enable elaboration of hyperstoichiometric plutonium dioxide. These results could mean that plutonium dioxide oxidation only occurs under very specific conditions.

Philippe Martin; Stéphane Grandjean; Michel Ripert; Michel Freyss; Pierre Blanc; Thierry Petit

2003-01-01

204

Inner-Shell Excitation Spectroscopy and X-ray Photoemission Electron Microscopy of Adhesion Promoters  

E-print Network

Inner-Shell Excitation Spectroscopy and X-ray Photoemission Electron Microscopy of Adhesion, and AdVanced Electronic Materials, The Dow Chemical Company, 1712 Building, Midland, Michigan 48674 ReceiVed: January 11, 2005 The C 1s, Si 2p, Si 2s, and O 1s inner-shell excitation spectra of vinyltriethoxysilane

Hitchcock, Adam P.

205

Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy Dissertation  

E-print Network

Atmospheric Corrosion of Silver Investigated by X-ray Photoelectron Spectroscopy Dissertation Atmospheric corrosion is a costly problem. Accelerated laboratory tests, such as the salt fog chamber, have been created to predict corrosion of materials without the need to expose them over long periods

206

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

207

X-ray photon correlation spectroscopy using the Mythen 1D detector  

NASA Astrophysics Data System (ADS)

X-ray Photon Correlation Spectroscopy (XPCS) is an experimental technique to measure the dynamics of materials on nano- and microscales. Often, the maximum frame rate of the detector limits which dynamical processes can be investigated. This study examines the applicability of the Mythen 1D detector for coherent scattering applications with special focus on XPCS experiments.

Westermeier, F.; Zozulya, A. V.; Bondarenko, S.; Parenti, A.; Lohmann, M.; Schavkan, A.; Grübel, G.; Sprung, M.

2013-03-01

208

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

209

Quantitative arsenic speciation in mine tailings using X-ray absorption spectroscopy  

Microsoft Academic Search

X-ray absorption fine structure spectroscopy (XAFS) was used to determine arsenic (As) oxidation state, local coordination (to a radius of 7Aaround As), and the relative proportion of different As species in model compounds and three California mine wastes: fully oxidized tailings (Ruth Mine), partially oxidized tailings (Argonaut Mine), and roast- ed sulfide ore (Spenceville Mine). Mineralogy was characterized by Rietveld

ANDREA L. FOSTER; GORDON E. BROWN JR; TRACY N. TINGLE; GEORGE A. PARKS

210

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

211

Highly Sensitive Nitric Oxide Detection Using X-ray Photoelectron Spectroscopy  

E-print Network

to stably bond monolayers of an iron heme complex onto silicon that enables direct, quantitative detectionHighly Sensitive Nitric Oxide Detection Using X-ray Photoelectron Spectroscopy Manish Dubey, Steven and direct detection of NO at these levels is important. NO is also a decomposition product of several

Schwartz, Jeffrey

212

X-ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films  

E-print Network

X-ray Absorption Spectroscopy of Transition Metal-Magnesium Hydride Thin Films T. J. Richardsona@lbl.gov Abstract Mixed metal thin films containing magnesium and a first-row transition element exhibit very large and coordination of the magnesium and transition metal atoms during hydrogen absorption were studied using dynamic

213

Flood control-mesh and X-ray fluorescence spectroscopy based system for city drainage  

Microsoft Academic Search

This paper presents a conceptual model of a system to prevent the clogging of drainage water and avoid spill over onto the roads by utilising a graduated mesh based automatic solid waste separator. The main purpose is to automatically segregate garbage in flowing drainage water, identify and separate plastic using x-ray spectroscopy, collect it and recycle it instead of letting

Anaisha Jaykumar; Swati Padmanabhan

2011-01-01

214

High-resolution soft X-ray beamline ADRESS at the Swiss Light Source for resonant inelastic X-ray scattering and angle-resolved photoelectron spectroscopies  

PubMed Central

The concepts and technical realisation of the high-resolution soft X-ray beamline ADRESS operating in the energy range from 300 to 1600?eV and intended for resonant inelastic X-ray scattering (RIXS) and angle-resolved photoelectron spectroscopy (ARPES) are described. The photon source is an undulator of novel fixed-gap design where longitudinal movement of permanent magnetic arrays controls not only the light polarization (including circular and 0–180° rotatable linear polarizations) but also the energy without changing the gap. The beamline optics is based on the well established scheme of plane-grating monochromator operating in collimated light. The ultimate resolving power E/?E is above 33000 at 1?keV photon energy. The choice of blazed versus lamellar gratings and optimization of their profile parameters is described. Owing to glancing angles on the mirrors as well as optimized groove densities and profiles of the gratings, the beamline is capable of delivering high photon flux up to 1 × 1013?photons s?1 (0.01% BW)?1 at 1?keV. Ellipsoidal refocusing optics used for the RIXS endstation demagnifies the vertical spot size down to 4?µm, which allows slitless operation and thus maximal transmission of the high-resolution RIXS spectrometer delivering E/?E > 11000 at 1?keV photon energy. Apart from the beamline optics, an overview of the control system is given, the diagnostics and software tools are described, and strategies used for the optical alignment are discussed. An introduction to the concepts and instrumental realisation of the ARPES and RIXS endstations is given. PMID:20724785

Strocov, V. N.; Schmitt, T.; Flechsig, U.; Schmidt, T.; Imhof, A.; Chen, Q.; Raabe, J.; Betemps, R.; Zimoch, D.; Krempasky, J.; Wang, X.; Grioni, M.; Piazzalunga, A.; Patthey, L.

2010-01-01

215

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

216

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. PMID:22583220

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

2012-01-01

217

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

218

Nanoelectron spectroscopy for chemical analysis: a novel energy filter for imaging x-ray photoemission spectroscopy  

NASA Astrophysics Data System (ADS)

A novel instrument for imaging ESCA is described. It is based on a tandem arrangement of two hemispherical energy analysers used as an imaging energy filter. The main spherical aberration (?2-term) of the analyser is corrected by the antisymmetry of the tandem configuration. The kinetic energy range useable for imaging extends up to 1.6 keV this is compatible with Mg and Al K? laboratory x-ray sources. First experiments on the chemical surface composition of a Cu0.98Bi0.02 polycrystal, a GaAs/AlGaAs heterostructure and Ag crystallites on Si(111) have been performed using synchrotron radiation. The results reveal an energy resolution of 190 meV and a lateral resolution (edge resolution) of 120 nm. Besides elimination of the analyser's spherical aberration, the tandem arrangement largely retains the time structure of the electron signal, unlike a single hemispherical analyser.

Escher, M.; Weber, N.; Merkel, M.; Ziethen, C.; Bernhard, P.; Schönhense, G.; Schmidt, S.; Forster, F.; Reinert, F.; Krömker, B.; Funnemann, D.

2005-04-01

219

Probing Multilayer Nanostructures with Photoelectron and X-Ray Emission Spectroscopies Excited by X-Ray Standing Waves  

NASA Astrophysics Data System (ADS)

We discuss a newly developed X-ray standing wave/wedge method for probing the composition, magnetization, and electronic densities of states in buried layers and interfaces of spintronic and other nanostructures. In work based on photoemission, this method has permitted determining concentration and magnetization profiles through giant magnetoresistive and magnetic tunnel junction structures, as well as individual layer densities of states near the Fermi level in a tunnel junction . Using X-ray emission and resonant inelastic X-ray scattering for detection has permitted probing deeper layers and interfaces in a giant magnetoresistance structure. Various future applications of this method in nanomagnetism and other fields of nanoscience are suggested, including using more energetic hard X-ray standing waves so as to probe more deeply below a surface and standing wave excitation in spectromicroscopy to provide depth sensitivity.

Yang, S.-H.; Sell, B. C.; Mun, B. S.; Fadley, C. S.

2013-01-01

220

High-resolution spectroscopy and high-density monitoring in X-rays of novae  

NASA Astrophysics Data System (ADS)

The 21st century X-ray observatories XMM-Newton, Chandra, and Swift gave us completely new insights into the X-ray behaviour of nova outbursts. These new-generation X-ray observatories provide particularly high spectral resolution and high density in monitoring campaigns, simultaneously in X-rays and UV/optical. The entire evolution of several nova outbursts has been observed with the Swift XRT and UVOT instruments, allowing studies of the gradual shift of the peak of the SED from UV to X-rays, time scales to the onset and duration of the X-ray brightest supersoft source (SSS) phase, and pre- and post-SSS X-ray emission. In addition, XMM-Newton and Chandra observations can efficiently be scheduled, allowing deeper studies of strategically chosen evolutionary stages. Before Swift joined in 2005, Chandra and XMM-Newton blind shots in search of SSS emission unavoidably led to some underexposed observations taken before and/or after the SSS phase. More systematic Swift studies reduced this number while increasing the number of novae. Pre- and post-SSS spectra at low and high spectral resolution were successfully modelled with collisional plasma models. Pre-SSS emission arises in shocks and post-SSS emission in radiatively cooling thin ejecta. In contrast, the grating spectra taken during the SSS phase are a lot more complex than expected and have not yet been successfully modeled. Available hot white dwarf (WD) radiation transport models give only approximate reproduction of the observations, and make some critical assumptions that are only valid in isolated WDs. More grating spectra would be important to search for systematic trends between SSS spectra and system parameters. Summary of well-established discoveries with Swift, XMM-Newton, and Chandra: - About 50% of novae display faint X-ray emission before the start of the SSS phase - The start of the SSS phase is not a smooth process. High-amplitude variations during the early SSS phase were seen that disappear close to the time when the optical plateau phase begins. - The end of the SSS phase is in most cases a smooth process. - The SSS grating spectra contain continuum spectra that roughly resemble a blackbody shape - The SSS X-ray grating spectra of systems with known high inclination angles contain emission lines on top of the continuum - The SSS X-ray spectra of systems with unknown or low inclination angles contain deep absorption lines from the interstellar medium and local, high-ionisation absorption lines that are blue shifted.

Ness, J. U.

2012-09-01

221

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

222

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

223

Photon statistics and speckle visibility spectroscopy with partially coherent X-rays.  

PubMed

A new approach is proposed for measuring structural dynamics in materials from multi-speckle scattering patterns obtained with partially coherent X-rays. Coherent X-ray scattering is already widely used at high-brightness synchrotron lightsources to measure dynamics using X-ray photon correlation spectroscopy, but in many situations this experimental approach based on recording long series of images (i.e. movies) is either not adequate or not practical. Following the development of visible-light speckle visibility spectroscopy, the dynamic information is obtained instead by analyzing the photon statistics and calculating the speckle contrast in single scattering patterns. This quantity, also referred to as the speckle visibility, is determined by the properties of the partially coherent beam and other experimental parameters, as well as the internal motions in the sample (dynamics). As a case study, Brownian dynamics in a low-density colloidal suspension is measured and an excellent agreement is found between correlation functions measured by X-ray photon correlation spectroscopy and the decay in speckle visibility with integration time obtained from the analysis presented here. PMID:25343797

Li, Luxi; Kwa?niewski, Pawe?; Orsi, Davide; Wiegart, Lutz; Cristofolini, Luigi; Caronna, Chiara; Fluerasu, Andrei

2014-11-01

224

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. 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

2012-01-01

225

X-ray absorption spectroscopy at the Ni-K edge in Stackhousia tryonii Bailey hyperaccumulator  

SciTech Connect

Young plants of Stackhousia tryonii Bailey were exposed to 34 mM Ni kg-1 in the form of NiSO4- 6H2O solution and grown under controlled glasshouse conditions for a period of 20 days. Fresh leaf, stem and root samples were analysed in vivo by micro x-ray absorption spectroscopy (XAS) at the Ni-K edge.Both x-ray absorption near edge structure and extended x-ray absorption fine structure spectra were analysed, and theresulting spectra were compared with spectra obtained from nine biologically important Ni-containing model compounds. The results revealed that themajority of leaf, stem and root Ni in the hyperaccumulator was chelated by citrate.Our results also suggest that in leavesNi is complexed by phosphate and histidine, and in stems and roots, phytate and histidine. The XAS results provide an important physiological insightinto transport, detoxification and storage of Ni in S. tryonii plants.

Ionescu, Mihail; Bhatia, Naveen P.; Cohen , David D.; Siegele, R.; Marcus, Matthew A.; Fakra, Sirine C.; Foran, G.; Kachenko, A.

2007-10-08

226

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

227

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

228

Simultaneous Femtosecond X-ray Spectroscopy and Diffraction of Photosystem II at Room Temperature  

PubMed Central

Intense femtosecond X-ray pulses produced at the Linac Coherent Light Source (LCLS) were used for simultaneous X-ray diffraction (XRD) and X-ray emission spectroscopy (XES) of microcrystals of Photosystem II (PS II) at room temperature. This method probes the overall protein structure and the electronic structure of the Mn4CaO5 cluster in the oxygen-evolving complex of PS II. XRD data are presented from both the dark state (S1) and the first illuminated state (S2) of PS II. Our simultaneous XRD/XES study shows that the PS II crystals are intact during our measurements at the LCLS, not only with respect to the structure of PS II, but also with regard to the electronic structure of the highly radiation sensitive Mn4CaO5 cluster, opening new directions for future dynamics studies. PMID:23413188

Kern, Jan; Alonso-Mori, Roberto; Tran, Rosalie; Hattne, Johan; Gildea, Richard J.; Echols, Nathaniel; Glöckner, Carina; Hellmich, Julia; Laksmono, Hartawan; Sierra, Raymond G.; Lassalle-Kaiser, Benedikt; Koroidov, Sergey; Lampe, Alyssa; Han, Guangye; Gul, Sheraz; DiFiore, Dörte; Milathianaki, Despina; Fry, Alan R.; Miahnahri, Alan; Schafer, Donald W.; Messerschmidt, Marc; Seibert, M. Marvin; Koglin, Jason E.; Sokaras, Dimosthenis; Weng, Tsu-Chien; Sellberg, Jonas; Latimer, Matthew J.; Grosse-Kunstleve, Ralf W.; Zwart, Petrus H.; White, William E.; Glatzel, Pieter; Adams, Paul D.; Bogan, Michael J.; Williams, Garth J.; Boutet, Sébastien; Messinger, Johannes; Zouni, Athina; Sauter, Nicholas K.; Yachandra, Vittal K.; Bergmann, Uwe; Yano, Junko

2013-01-01

229

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

230

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

231

EUV and X-ray Spectroscopy of the Active Sun  

NASA Astrophysics Data System (ADS)

This thesis strives to improve our understanding of solar activity, specifically the behaviour of solar flares and coronal mass ejections. An investigation into the hydrodynamic evolution of a confined solar flare was carried out using RHESSI, CDS, GOES and TRACE. Evidence for pre-flare heating, explosive and gentle chromospheric evaporation and loop draining were observed in the data. The observations were compared to a 0-D hydrodynamic model, EBTEL, to aid interpretation. This led to the conclusion that the flare was not heated purely by non-thermal beam heating as previously believed, but also required direct heating of the plasma. An observational investigation in to the initiation mechanism of a coronal mass ejection and eruptive flare was then carried out, again utilising observations from a wide range of spacecraft: MESSENGER/SAX, RHESSI, EUVI, Cor1 and Cor2. Observations provided evidence of CME triggering by internal tether-cutting and not by breakout reconnection. A comparison of the confined and eruptive flares suggests that while they have different characteristics, timescales and topologies, these two phenomena are the result of the same fundamental processes. Finally, an investigation into the sensitivity of EUV imaging telescopes was carried out. This study established a new technique for calculating the sensitivity of EUV imagers to plasmas of different temperatures for four different types of plasma: coronal hole, quiet sun, active region and solar flare. This was carried out for six instruments: Proba-2/SWAP, TRACE, SOHO/EIT, STEREO A/EUVI, STEREO B/EUVI and SDO/AIA. The importance of considering the multi-thermal nature of these instruments was then put into the context of investigating explosive solar activity.

Raftery, Claire L.

2012-10-01

232

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

E-print Network

XANES spectroscopies at beamline X18B at the National Synchrotron Light Source. The channel cut Si 111- tion spectroscopy XAS was developed in energy dispersive and quick extended x-ray absorption fine range spectroscopy. Initial development of QEXAFS was with a relatively slow IK320 optical encoder

Sparks, Donald L.

233

SURFACE SEGREGATION STUDIES OF SOFC CATHODES: COMBINING SOFT X-RAYS AND ELECTROCHEMICAL IMPEDENCE SPECTROSCOPY  

SciTech Connect

A system to grow heteroepitaxial thin-films of solid oxide fuel cell (SOFC) cathodes on single crystal substrates was developed. The cathode composition investigated was 20% strontium-doped lanthanum manganite (LSM) grown by pulsed laser deposition (PLD) on single crystal (111) yttria-stabilized zirconia (YSZ) substrates. By combining electrochemical impedance spectroscopy (EIS) with x-ray photoemission spectroscopy (XPS) and x-ray absorption spectroscopy XAS measurements, we conclude that electrically driven cation migration away from the two-phase gas-cathode interface results in improved electrochemical performance. Our results provide support to the premise that the removal of surface passivating phases containing Sr2+ and Mn2+, which readily form at elevated temperatures even in O2 atmospheric pressures, is responsible for the improved cathodic performance upon application of a bias.

Miara, Lincoln J.; Piper, L.F.J.; Davis, Jacob N.; Saraf, Laxmikant V.; Kaspar, Tiffany C.; Basu, Soumendra; Smith, K. E.; Pal, Uday B.; Gopalan, Srikanth

2010-12-01

234

Thermal design and performance of the REgolith x-ray imaging spectrometer (REXIS) instrument  

NASA Astrophysics Data System (ADS)

The REgolith X-ray Imaging Spectrometer (REXIS) instrument is a student collaboration instrument on the OSIRIS-REx asteroid sample return mission scheduled for launch in September 2016. The REXIS science mission is to characterize the elemental abundances of the asteroid Bennu on a global scale and to search for regions of enhanced elemental abundance. The thermal design of the REXIS instrument is challenging due to both the science requirements and the thermal environment in which it will operate. The REXIS instrument consists of two assemblies: the spectrometer and the solar X-ray monitor (SXM). The spectrometer houses a 2x2 array of back illuminated CCDs that are protected from the radiation environment by a one-time deployable cover and a collimator assembly with coded aperture mask. Cooling the CCDs during operation is the driving thermal design challenge on the spectrometer. The CCDs operate in the vicinity of the electronics box, but a 130 °C thermal gradient is required between the two components to cool the CCDs to -60 °C in order to reduce noise and obtain science data. This large thermal gradient is achieved passively through the use of a copper thermal strap, a large radiator facing deep space, and a two-stage thermal isolation layer between the electronics box and the DAM. The SXM is mechanically mounted to the sun-facing side of the spacecraft separately from the spectrometer and characterizes the highly variable solar X-ray spectrum to properly interpret the data from the asteroid. The driving thermal design challenge on the SXM is cooling the silicon drift detector (SDD) to below -30 °C when operating. A two-stage thermoelectric cooler (TEC) is located directly beneath the detector to provide active cooling, and spacecraft MLI blankets cover all of the SXM except the detector aperture to radiatively decouple the SXM from the flight thermal environment. This paper describes the REXIS thermal system requirements, thermal design, and analyses, with a focus on the driving thermal design challenges for the instrument. It is shown through both analysis and early testing that the REXIS instrument can perform successfully through all phases of its mission.

Stout, Kevin D.; Masterson, Rebecca A.

2014-08-01

235

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

236

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

NASA Astrophysics Data System (ADS)

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.; Lenhard, T.; Hanson, J.; Wang, Q.; Frenkel, A. I.; Marinkovic, N.; Hould, N.; Ginder-Vogel, M.; Landrot, G. L.; Sparks, D. L.; Ganjoo, A.

2010-01-01

237

Structural study on (CH3)2)S/Cu(100 by near edge x-ray absorption fine structure and x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

We have investigated the (CH3)2)S/Cu(100 system using polarization dependent S K-edge near edge x-ray absorption fine structure (NEXAFS) and x-ray photoelectron spectroscopy (XPS) for both S 1s and C 1s electrons. From the XPS results, the (CH3)2S molecule is found to adsorb through the sulfur atom on the Cu(100) surface. There is a little polarization dependence in the S K-edge NEXAFS spectra for submonolayer phase. The orientation angle of the molecular plane is estimated to be 33deg from the surface. copyright 2002 American Vacuum Society.

Yagi, S.; Nakano, Y.; Ikenaga, E.; Sardar, S. A.; Syed, J. A.; Soda, K.; Hashimoto, E.; Tanaka, K.; Taniguchi, M.

2002-09-01

238

The GALAXIES beamline at the SOLEIL synchrotron: inelastic X-ray scattering and photoelectron spectroscopy in the hard X-ray range.  

PubMed

The GALAXIES beamline at the SOLEIL synchrotron is dedicated to inelastic X-ray scattering (IXS) and photoelectron spectroscopy (HAXPES) in the 2.3-12?keV hard X-ray range. These two techniques offer powerful complementary methods of characterization of materials with bulk sensitivity, chemical and orbital selectivity, resonant enhancement and high resolving power. After a description of the beamline components and endstations, the beamline capabilities are demonstrated through a selection of recent works both in the solid and gas phases and using either IXS or HAXPES approaches. Prospects for studies on liquids are discussed. PMID:25537606

Rueff, J P; Ablett, J M; Céolin, D; Prieur, D; Moreno, Th; Balédent, V; Lassalle-Kaiser, B; Rault, J E; Simon, M; Shukla, A

2015-01-01

239

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

240

Ni-(In,Ga)As Alloy Formation Investigated by Hard-X-Ray Photoelectron Spectroscopy and X-Ray Absorption Spectroscopy  

NASA Astrophysics Data System (ADS)

The electrical, chemical, and structural interactions between Ni films and In 0.53Ga 0.47A s for source-drain applications in transistor structures have been investigated. It was found that for thick (>10 nm ) Ni films, a steady decrease in sheet resistance occurs with increasing anneal temperatures, however, this trend reverses at 450 °C for 5 nm thick Ni layers, primarily due to the agglomeration or phase separation of the Ni-(In,Ga)As layer. A combined hard-x-ray photoelectron spectroscopy (HAXPES) and x-ray absorption spectroscopy (XAS) analysis of the chemical structure of the Ni-(In,Ga)As alloy system shows: (1) that Ni readily interacts with In 0.53Ga 0.47A s upon deposition at room temperature resulting in significant interdiffusion and the formation of NiIn, NiGa, and NiAs alloys, and (2) the steady diffusion of Ga through the Ni layer with annealing, resulting in the formation of a Ga2O3 film at the surface. The need for the combined application of HAXPES and XAS measurements to fully determine chemical speciation and sample structure is highlighted and this approach is used to develop a structural and chemical compositional model of the Ni-(In,Ga)As system as it evolves over a thermal annealing range of 250 to 500 °C .

Walsh, Lee A.; Hughes, Greg; Weiland, Conan; Woicik, Joseph C.; Lee, Rinus T. P.; Loh, Wei-Yip; Lysaght, Pat; Hobbs, Chris

2014-12-01

241

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

242

In Situ Identification of Mineral Resources with an X-Ray-Optical "Hands-Lens" Instrument  

NASA Technical Reports Server (NTRS)

The recognition of material resources on a planetary surface requires exploration strategies not dissimilar to those employed by early field geologists who searched for ore deposits primarily from surface clues. In order to determine the location of mineral ores or other materials, it will be necessary to characterize host terranes at regional or subregional scales. This requires geographically broad surveys in which statistically significant numbers of samples are rapidly scanned from a roving platform. To enable broad-scale, yet power-conservative planetary-surface exploration, we are developing an instrument that combines x-ray diffractometry (XRD), x-ray fluorescence spectrometry (XRF), and optical capabilities; the instrument can be deployed at the end of a rover's robotic arm, without the need for sample capture or preparation. The instrument provides XRD data for identification of mineral species and lithological types; diffractometry of minerals is conducted by ascertaining the characteristic lattice parameters or "d-spacings" of mineral compounds. D-spacings of 1.4 to 25 angstroms can be determined to include the large molecular structures of hydrated minerals such as clays. The XRF data will identify elements ranging from carbon (Atomic Number = 6) to elements as heavy as barium (Atomic Number = 56). While a sample is being x-rayed, the instrument simultaneously acquires an optical image of the sample surface at magnifications from lx to at least 50x (200x being feasible, depending on the sample surface). We believe that imaging the sample is extremely important as corroborative sample-identification data (the need for this capability having been illustrated by the experience of the Pathfinder rover). Very few geologists would rely on instrument data for sample identification without having seen the sample. Visual inspection provides critical recognition data such as texture, crystallinity, granularity, porosity, vesicularity, color, lustre, opacity, and so forth. These data can immediately distinguish sedimentary from igneous rocks, for example, and can thus eliminate geochemical or mineral ambiguities arising, say between arkose and granite. It would be important to know if the clay being analyzed was part of a uniform varve deposit laid down in a quiescent lake, or the matrix of a megabreccia diamictite deposited as a catastrophic impact ejecta blanket. The unique design of the instrument, which combines Debye-Scherrer geometry with elements of standard goniometry, negates the need for sample preparation of any kind, and thus negates the need for power-hungry and mechanically-complex sampling systems that would have to chip, crush, sieve, and mount the sample for x-ray analysis. Instead, the instrument is simply rested on the sample surface of interest (like a hand lens); the device can interrogate rough rock surfaces, coarse granular material, or fine rock flour. A breadboard version of the instrument has been deployed from the robotic arm of the Marsokhod rover in field trials at NASA Ames, where large vesicular boulders were x-rayed to demonstrate the functionality of the instrument design, and the ability of such a device to comply with constraints imposed by a roving platform. Currently under development is a flight prototype concept of this instrument that will weigh 0.3 kg, using about 4500 J of energy per sample analysis. It requires about 5 min. for XRD analysis, and about 30 min. for XRF interrogation. Its small mass and rugged design make it ideal for deployment on small rovers of the type currently envisaged for the exploration of Mars (e.g., Sojourner-scale platforms). The design utilizes a monolithic P-N junction photodiode pixel array for XRD, a Si PIN photodiode/avalanche photodiode system for XRF, and an endoscopic imaging camera system unobtrusively embedded between the detectors and the x-ray source (the endoscope with its board-mounted camera can be adapted for IR light in addition to visible wavelenths. A rugged, miniature (7 cu cm) x-ray source for the instrument has already b

Marshall, J.; Koppel, L.; Bratton, C.; Metzger, E.; Hecht, M.

1999-01-01

243

Efficient X-ray short pulse generation from femtosecond laser-produced plasma for pump-probe spectroscopy  

Microsoft Academic Search

X-rays emitted from high-density plasmas created by femtosecond laser pulses are of great interest. Since such X-rays are synchronized to the laser pulse, these sources in the short pulse regime are expected to provide high temporal resolution in X-ray diffraction, absorption spectroscopy, and other applications used to measure the dynamic processes in optically excited materials. In this paper, we describe

H. Nakano; T. Nishikawa; K. Oguri; N. Uesugi

2000-01-01

244

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. PMID:22737179

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

245

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

246

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

247

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

248

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

249

A high resolution multipurpose ESCA instrument with X-ray monochromator  

NASA Astrophysics Data System (ADS)

The design and performance of a new high resolution multipurpose instrument are described and illustrated. The instrument comprises a high-power, fine-focusing e --gun, a high speed rotating anode, a double focusing multi-crystal X-ray monochromator, a monochromatic UV-source with a toroidal grating, a fine-focus variable energy e --source, a four-element electrostatic e --lens system, a large 36 cm hemispherical electrostatic analyzer, a 12 cm wide electron multi-detector system and a dedicated computer system. Various sample probes for gases, liquids and solids are discussed. The instrument is shown to reach an energy resolution of at least 0.23 eV with X-ray excitation at a sufficient intensity to enable the study of gases. A number of illustrative examples of the proved instrumental performance is presented. A new "line-sharpening" effect, due to post-collision interaction in Auger electron spectra, is revealed due to the high spectrometer resolution. The strongest vibrational components of the C 1s ESCA line from methane are for the first time resolved. High resolution spectra are also presented for solids, e.g. the spin-orbit split Si 2p line is well resolved into two components and new resolved structures appear in the Ag and Au valence bands. Calculated density of states are found to be in good agreement with these structure rich d-bands. Phonon excitation accompanying the photoionization process is discussed in relation to its causing additional broadening of the Si 2p lines.

Gelius, U.; Asplund, L.; Basilier, E.; Hedman, S.; Helenelund, K.; Siegbahn, K.

1984-01-01

250

Characterization of an Yb:LuVO 4 single crystal using X-ray topography, high-resolution X-ray diffraction, and X-ray photoelectron spectroscopy  

Microsoft Academic Search

Knowledge on the defect and electronic structure allows for improved modeling of material properties. A short literature review has shown that the information on defect structure of rare earth orthovanadate single crystals is limited. In this paper, defect and electronic structure of a needle-shaped Yb:LuVO4 single crystal grown by the slow cooling method have been studied by means of X-ray

W. Paszkowicz; P. Romanowski; J. Bak-Misiuk; W. Wierzchowski; K. Wieteska; W. Graeff; R. J. Iwanowski; M. H. Heinonen; O. Ermakova; H. Dabkowska

2011-01-01

251

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

252

Local detection of X-ray spectroscopies with an in-situ Atomic Force Microscope  

E-print Network

We show how the in situ combination of Scanning Probe Microscopies (SPM) with X-ray microbeams enables many new experiments in the synchrotron radiation domain. Our instrument is based on an optics free AFM/STM that can be directly installed on most of the SR X-ray end stations. The instrument can be simply used for AFM imaging of the investigated sample or it can be used for detection of photoemitted electrons with a sharp STM like tungsten tip, thus leading to locally measure the EXAFS signal. Alternatively one can measure the photons absorbed by the tip, thus locally detecting diffraction. In this paper, we show examples of both measurements. We also describe the experimental setup and the tip-beam interaction that is a key point for alignment procedures. We finally show how these features can be exploited in an extended variety of domains, nanosciences and nanomechanics, just to name a few.

Rodrigues, Mario S; LE Denmat, Simon; Chevrier, Joel; Felici, Roberto; Comin, Fabio

2008-01-01

253

Application of gas microstrip detectors for X-ray absorption spectroscopy in common process gases.  

PubMed

We report upon the design of a new gas microstrip detector (GMSD) for use in X-ray absorption spectroscopy applied to the study of catalysis and material science. We show that GMSDs can operate not only with the gas mixtures normally used in proportional counters but also with the majority of gas mixtures used in common catalytic reactions. The detector functions well in the presence of water vapor. EXAFS investigations of a test system of NiO on Ni metal are discussed in which it is demonstrated that depth profiling using electron yield X-ray absorption spectroscopy is possible in a wide variety of gaseous environments. Electron detection of XAS using GMSDs is applicable to metals, semiconductors, and insulators presented in almost all forms of sample including films, pellets, powders, crystals, and liquids. PMID:16465709

Vollmer, Antje; Lipp, John D; Lee, Jonathan R I; Derbyshire, Gareth E; Rayment, Trevor

2003-12-01

254

X-Ray Spectroscopy of the Photosynthetic Oxygen-Evolving Complex  

SciTech Connect

Water oxidation to dioxygen in photosynthesis is catalyzed by a Mn{sub 4}Ca 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, K.; Yano, J.; Yachandra, V.K.

2009-05-27

255

Electrochemical flowcell for in-situ investigations by soft x-ray absorption and emission spectroscopy  

SciTech Connect

A new liquid flow-cell designed for electronic structure investigations at the liquid-solid interface by soft X-ray absorption and emission spectroscopy is presented. A thin membrane serves simultaneously as a substrate for the working electrode and solid state samples as well as for separating the liquid from the surrounding vacuum conditions. In combination with counter and reference electrodes this approach allows in-situ studies of electrochemical deposition processes and catalytic reactions at the liquid-solid interface in combination with potentiostatic measurements. As model system in-situ monitoring of the deposition process of Co metal from a 10 mM CoCl{sub 2} aqueous solution by X-ray absorption and emission spectroscopy is presented.

Schwanke, C.; Lange, K. M., E-mail: Kathrin.lange@helmholtz-berlin.de [Helmholtz-Zentrum Berlin für Materialien und Energie, Institute of Solar Fuels, Albert-Einstein-Straße 15, 12489 Berlin (Germany); Golnak, R.; Xiao, J. [Helmholtz-Zentrum Berlin für Materialien und Energie, Institute of Methods for Material Development, Albert-Einstein-Straße 15, 12489 Berlin (Germany)

2014-10-15

256

Column Densities Towards Three Bursting Low-Mass X-ray Binaries from High Resolution X-ray Spectroscopy  

E-print Network

We measured the galactic hydrogen column densities to the neutron-star binaries GX 17+2, 4U 1705-44, and 4U 1728-34 by modeling the Mg and Si absorption edges found in high-resolution X-ray spectra obtained by the Chandra X-ray Observatory. We found for GX 17+2, N_H = (2.38 +/- 0.12) x 10^22 cm^-2, for 4U 1705-44, N_H = (2.44 +/- 0.09) x 10^22 cm^-2, and for 4U 1728-34, N_H = (2.49 +/- 0.14) x 10^22 cm^-2. These values are in reasonable agreement with the hydrogen column densities inferred earlier from modeling of the continuum spectra of the sources. Our results can be used to constrain the uncertainties of model parameters of the X-ray spectra of these sources that are correlated to the uncertainties of the hydrogen column density. In the case of continuum spectra obtained during thermonuclear X-ray bursts, they will significantly reduce the uncertainties in the spectroscopically measured masses and radii of the neutron stars.

Patricia Wroblewski; Tolga Guver; Feryal Ozel

2008-09-30

257

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

258

A study of synthetic and natural uranium oxides by X-ray photoelectron spectroscopy  

Microsoft Academic Search

Synthetic and natural uranium oxides UOx (2?×?3) have been studied with X-ray photoelectron spectroscopy (XPS) to determine the phase composition and content of uranium ions in uraninites with a varying degree of oxidation. A strong hybridization of U6p and O2s orbitals has been found which permits a quantitative assessment of the U-O bond lengths. The values of such bonds in

Yu. A. Teterin; V. M. Kulakov; A. S. Baev; N. B. Nevzorov; I. V. Melnikov; V. A. Streltsov; L. G. Mashirov; D. N. Suglobov; A. G. Zelenkov

1981-01-01

259

Characterization of covalently bonded proteins on poly(methyl methacrylate) by X-ray photoelectron spectroscopy  

Microsoft Academic Search

X-ray photoelectron spectroscopy (XPS) has been used to characterize a poly(methyl methacrylate) (PMMA) surface with covalently attached proteins. The PMMA surfaces were first aminated using hexamethyldiamine; the resulting –NH2 sites were reacted with the hetero-bifunctional cross-linker Sulfo-EMCS to form a maleimide-terminated surface. The N-hydroxysuccinimide ester terminal and maleimide terminal groups of Sulfo-EMCS reacts with amine and sulfhydryl groups, respectively, exposed

Geoffrey W. Nelson; Megan Perry; Shu-Mei He; David L. Zechel; J. Hugh Horton

2010-01-01

260

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

SciTech Connect

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

Paesler, M.; Sayers, D.

1988-12-01

261

The cleanability of stainless steel as determined by X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The cleanability of stainless steel using a starch soil was investigated using X-ray photoelectron spectroscopy and atomic force microscopy. Two cleaning regimes were examined: high pressure spray system removed absorbed material much more effectively than mechanical action. Surface defects on the stainless steel acted as sites for soil retention. When starch was combined with the Staphylococcus aureus bacterium the two components were removed at different rates from the surface caused by difference in size between the starch molecules and bacterium cells.

Boyd, R. D.; Verran, J.; Hall, K. E.; Underhill, C.; Hibbert, S.; West, R.

2001-03-01

262

The use of (micro)-X-ray absorption spectroscopy in cement research  

Microsoft Academic Search

Long-term predictions on the mobility and the fate of radionuclides and contaminants in cementitious waste repositories require a molecular-level understanding of the geochemical immobilization processes involved. In this study, the use of X-ray absorption spectroscopy (XAS) for chemical speciation of trace elements in cementitious materials will be outlined presenting two examples relevant for nuclear waste management. The first example addresses

A. M.. Scheidegger; M. Vespa; D. Grolimund; E. Wieland; M. Harfouche; I. Bonhoure; R. Daehn

2006-01-01

263

The electronic structure study of titanium-nickel alloys by x-ray photoelectron spectroscopy  

Microsoft Academic Search

Purpose of the study. The purpose of the study was to investigate the electronic structure changes of titanium-nickel (Ti-Ni) alloys. The electronic structure was correlated with the physical property of shape memory effect demonstrated by 50% atomic nickel concentration Ti-Ni crystalline alloys. Methodology. The technique of x-ray photoelectron spectroscopy was used to collect spectra using an ESCA PHI 5100 system.

Michael A. Seabolt

2002-01-01

264

The use of in situ X-ray absorption spectroscopy in applied fuel cell research  

Microsoft Academic Search

For a detailed understanding and systematic optimization of fuel cell systems, in situ studies are an indispensable tool,\\u000a as they provide information on the catalyst structure in different operation conditions. X-ray absorption spectroscopy (XAS)\\u000a is in particular suitable for operando investigations, since it does not require ultra high vacuum conditions or long-range order in the sample. Furthermore, it\\u000a provides in

Virginie Croze; Frank Ettingshausen; Julia Melke; Matthias Soehn; Dominic Stuermer; Christina Roth

2010-01-01

265

HIGH-RESOLUTION CHANDRA SPECTROSCOPY OF SCORPII: A NARROW-LINE X-RAY SPECTRUM FROM A HOT STAR  

E-print Network

HIGH-RESOLUTION CHANDRA SPECTROSCOPY OF SCORPII: A NARROW-LINE X-RAY SPECTRUM FROM A HOT STAR, Scorpii poses a severe challenge to the standard picture of O-star wind-shock X-ray emission. The Chandra wind-shock framework. The many emission lines detected with the Chandra gratings are significantly

Cohen, David

266

X-ray absorption spectroscopy of the cubic and hexagonal polytypes of zinc sulfide B. Gilbert,1,  

E-print Network

X-ray absorption spectroscopy of the cubic and hexagonal polytypes of zinc sulfide B. Gilbert,1 Received 18 June 2002; published 26 December 2002 We investigate the sensitivity of x-ray absorption. Experimental spectra and multiple-scattering calculations are reported at the major absorption edges

Haskel, Daniel

267

Characterization of Delhi iron pillar rust by X-ray diÄraction, Fourier transform infrared spectroscopy and Mossbauer spectroscopy  

Microsoft Academic Search

Rust samples obtained from the region just below the decorative bell capital of the Delhi iron pillar (DIP) have been analyzed by X-ray diÄraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Mossbauer spectroscopy. The identification of iron hydrogen phosphate hydrate in the crystalline form by XRD was unambiguous. Very weak diÄraction from the oxyhydroxides\\/oxides of iron was observed indicating that

R. Balasubramaniam; A. V. Ramesh Kumar

268

X-ray induced reduction effects at CeO sub 2 surfaces: An x-ray photoelectron spectroscopy study  

SciTech Connect

XPS techniques are used to study the effects of Al {ital K}{alpha} x-rays on the surface chemical composition of CeO{sub 2}. We find that prolonged exposures cause the formation of some Ce{sup 3+} oxidic species at the surface. We have studied the Ce 3{ital p}, Ce 3{ital d}, O 1{ital s}, Ce 4{ital p}, Ce 4{ital d}, and valence band regions in an attempt to localize the depth of damage. Consideration of published formulations for electron attenuation lengths and electron inelastic mean free paths indicates that the chemical reduction occurs mainly in the first 15--20 A from the surface. Our results show that some of the XPS features, usually referred to as excited electronic states of ceria, are in fact induced by prolonged exposures to the x rays.

Paparazzo, E. (Istituto di Struttura della Materia del CNR, Via E. Fermi 38, 00044 Frascati, Italy (IT)); Ingo, G.M. (Istituto di Teoria e Struttura Elettronica, Area della Ricerca di Roma del CNR, Via Salaria km 29.500, 00016 Monterotondo, Italy (IT)); Zacchetti, N. (Centro Sviluppo Materiali S.p.A., Casella Postale 10747, Roma-Eur, Roma, Italy (IT))

1991-05-01

269

Simultaneous X-ray and Ultraviolet spectroscopy of the Seyfert galaxy NGC 5548. III. X-ray time variability  

E-print Network

The Seyfert 1 galaxy NGC 5548 was observed for a week by Chandra using both the HETGS and LETGS spectrometers. In this paper we study the time variability of the continuum radiation. During our observation, the source showed a gradual increase in flux over four days, followed by a rapid decrease and flattening of the light curve afterwards. Superimposed upon these relatively slow variations several short duration bursts or quasi-periodic oscillations occured with a typical duration of several hours and separation between 0.6-0.9 days. The bursts show a delay of the hard X-rays with respect to the soft X-rays of a few hours. We interprete these bursts as due to a rotating, fluctuating hot spot at approximately 10 gravitational radii; the time delay of the hard X-rays from the bursts agree with the canonical picture of Inverse Compton scattering of the soft accretion disk photons on a hot medium that is relatively close to the central black hole.

J. S. Kaastra; K. C. Steenbrugge; D. M. Crenshaw; S. B. Kraemer; N. Arav; I. M. George; D. A. Liedahl; R. L. J. van der Meer; F. B. S. Paerels; T. J. Turner; T. Yaqoob

2004-04-23

270

X-ray absorption spectroscopy study of prototype chemical systems: Theory vs. experiment  

NASA Astrophysics Data System (ADS)

Understanding the details of the intensities and spectral shapes of x-ray absorption spectra is a long-standing problem in chemistry and physics. Here, I present detailed studies of x-ray absorption for prototypical liquids, solids and gases with the goal of enhancing our general understanding of core-level spectroscopy via comparisons of modern theory and experiment. In Chapter 2, I investigate the importance of quantum motions in the x-ray absorption spectra of simple gases. It is found that rare fluctuations in atomic positions can be a cause of features in the spectra of gaseous molecules. In Chapter 3, I explore a novel quantization scheme for the excited and ground state potential surfaces for an isolated nitrogen molecule. This allows for the explicit calculation of the "correct" transition energies and peak widths (i.e. without any adjustable parameters). In Chapter 4, the importance of nuclear motion in molecular solids is investigated for glycine. We find that the inclusion of these motions permits the spectrum to be accurately calculated without any additional adjustable parameters. In Chapter 5, I provide a detailed study of the hydroxide ion solvated in water. There has been recent controversy as to how hydroxide is solvated, with two principal models invoked. I show that some of the computational evidence favoring one model of solvation over the other has been either previously obtained with inadequate precision or via a method that is systematically biased. In Chapter 6, the measured and computed x-ray absorption spectra of pyrrole in both the gas phase and when solvated by water are compared. We are able to accurately predict the spectra in both cases. In Chapter 7, the measured x-ray absorption of a series of highly charged cationic salts (YBr3, CrCl3, SnCl4 , LaCl3 and InCl3) solvated in water are presented and explained. In Chapter 8, the measured x-ray absorption spectrum at the nitrogen K-edge of aqueous triglycine is presented, including effects of various salts which can alter its solubility. This is used to show that while x-ray absorption is sensitive to salt interactions with small peptides, it is unlikely to be a sensitive probe for overall protein structures, i.e. to distinguish beta sheet from an alpha helix at the nitrogen K-edge. Finally, in Chapter 9 future directions are discussed.

Schwartz, Craig Philip

271

A short-pulse X-ray beamline for spectroscopy and scattering.  

PubMed

Experimental facilities for picosecond X-ray spectroscopy and scattering based on RF deflection of stored electron beams face a series of optical design challenges. Beamlines designed around such a source enable time-resolved diffraction, spectroscopy and imaging studies in chemical, condensed matter and nanoscale materials science using few-picosecond-duration pulses possessing the stability, high repetition rate and spectral range of synchrotron light sources. The RF-deflected chirped electron beam produces a vertical fan of undulator radiation with a correlation between angle and time. The duration of the X-ray pulses delivered to experiments is selected by a vertical aperture. In addition to the radiation at the fundamental photon energy in the central cone, the undulator also emits the same photon energy in concentric rings around the central cone, which can potentially compromise the time resolution of experiments. A detailed analysis of this issue is presented for the proposed SPXSS beamline for the Advanced Photon Source. An optical design that minimizes the effects of off-axis radiation in lengthening the duration of pulses and provides variable X-ray pulse duration between 2.4 and 16?ps is presented. PMID:25178012

Reininger, R; Dufresne, E M; Borland, M; Beno, M A; Young, L; Evans, P G

2014-09-01

272

Advancements in time-resolved x-ray laser induced time-of-flight photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Time-resolved soft x-ray photoelectron spectroscopy is used to probe the non-steady-state evolution of the valence band electronic structure of laser heated ultra-thin (50 nm) metal foils and bulk semiconductors. Single-shot soft x-ray laser induced time-of-flight photoelectron spectroscopy with picosecond time resolution was used in combination with optical measurements of the disassembly dynamics that have shown the existence of a metastable liquid phase in fs-laser heated metal foils persisting 4-5 ps. This metastable phase is studied using a 527 nm wavelength 400 fs laser pulse containing 0.3 - 2.5 mJ laser energy focused in a large 500 × 700 ?m2 spot to create heated conditions of 0.2 - 1.8 × 1012 W cm-2 intensity. The unique LLNL COMET compact tabletop soft x-ray laser source provided the necessary high photon flux, highly monoenergetic, picosecond pulse duration, and coherence for observing the evolution of changes in the valence band electronic structure of laser heated metals and semiconductors with picosecond time resolution. This work demonstrates the continuing development of a powerful new technique for probing reaction dynamics and changes of local order on surfaces on their fundamental timescales including phenomena such as non-thermal melting, chemical bond formation, intermediate reaction steps, and the existence of transient reaction products.

Nelson, A. J.; Dunn, J.; Widmann, K.; Ao, T.; Ping, Y.; Hunter, J.; Ng, A.

2005-09-01

273

Mineral identification in Colombian coals using Mössbauer spectroscopy and X-ray diffraction  

NASA Astrophysics Data System (ADS)

Minerals were identified in three Colombian coal samples from the Southwest of the country using Mössbauer spectroscopy and X-ray diffraction. Original and sink separated coal fractions of specific gravity 1.40 and 1.60 with particle size less than 600 µm were used in the study. Using Mössbauer spectroscopy, the minerals identified in the original coal samples were pyrite jarosite, ankerite, illite and ferrous sulfate, whereas by means of X-ray diffraction, minerals identified were kaolinite, quartz, pyrite, and jarosite. Differences in mineral composition were found in the original and sink separated fractions using both techniques. Mössbauer spectra show that the mineral phases in low concentrations such as illite, ankerite and ferrous sulfate do not always appear in the spectra of sink coals, despite of those minerals occurring in the original coal, due to the fact that they are associated with the organic matter and not liberated in the grinding process. X-ray results show that the peak intensity grows as the specific gravity is increased indicating that the density separation method could be an effective process to clean coal.

Fajardo, M.; Mojica, J.; Barraza, J.; Pérez Alcázar, G. A.; Tabares, J. A.

1999-11-01

274

X-ray photon correlation spectroscopy studies of the dynamics of self-assembling block copolymer structures  

E-print Network

Several improvements presented to the emerging technique of X-ray Photon Correlation Spectroscopy. These improvements enabled the study of polymer structures, in particular isotropic sponge phases of homo-polymer block ...

Falus, Péter, 1972-

2004-01-01

275

Use of X-ray Absorption Spectroscopy to Distinguish Between Inner And Outer-sphere Pb Adsorption Complexes on Montmorillonite  

E-print Network

Use of X-ray Absorption Spectroscopy to Distinguish Between Inner And Outer-sphere Pb Adsorption on the functional groups at the edges of the montmorillonite. At I = 0.002 M Pb absorption was less dependent

Sparks, Donald L.

276

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

277

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

278

Identifying catalyst in Li-N-H system by x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Chemical bonding states of titanium compounds in LiH and LiNH2 mixture, which have been a candidate for a hydrogen storage material, have been examined by x-ray absorption spectroscopy measurement as the characterization of the catalysts. The results of x-ray absorption near-edge structure indicated that the Ti atoms in the Ti compounds, which had the catalytic effect on the kinetics of the hydrogen desorption properties, had a common electronic (chemical bonding) state. Additionally, this common electronic state of the Ti catalysts agrees with that of TiCl3.5NH3. These results indicated that TiCl3.5NH3 could act as the catalyst.

Isobe, Shigehito; Hino, Satoshi; Ichikawa, Takayuki; Kojima, Yoshitsugu

2011-07-01

279

X-ray absorption spectroscopy of the dimeric iron site in azidomethemerythrin from Phascolopsis gouldii.  

PubMed Central

X-ray absorption spectroscopy has been used to study the dimeric iron center in azidomethemerythrin from Phascolopsis gouldii. Absorption edge data confirm that the two iron atoms are present as Fe(III) and suggest a hexa-coordination site for each of the iron atoms. The extended x-ray absorption fine structure (EXAFS) analysis provides direct structural evidence of a mu-oxo bridge between the two iron atoms at an average Fe-O distance of 1.71-1.76 A. Analysis using a multiple-scattering formalism calculates upper limits of 165 degrees for the Fe-O-Fe bridging angle and 3.38 A for the Fe-Fe distance. This result agrees with current crystallographic models being determined by refinement of structures of two azidomethemerythrins. PMID:6959115

Hendrickson, W A; Co, M S; Smith, J L; Hodgson, K O; Klippenstein, G L

1982-01-01

280

Wiggler-base Hard X-ray Spectroscopy Beamline at CLS  

SciTech Connect

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. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK (Canada); Department of Physics, University of Guelph, Guelph ON N1G 2W1 (Canada); Chen, N. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK (Canada); Geological Sciences Department, University of Saskachewan, Saskatoon, SK (Canada); Sheng, W. [Canadian Light Source, University of Saskatchewan, Saskatoon, SK (Canada)

2007-01-19

281

Note: Sample chamber for in situ x-ray absorption spectroscopy studies of battery materials  

NASA Astrophysics Data System (ADS)

In situ x-ray absorption spectroscopy (XAS) provides element-specific characterization of both crystalline and amorphous phases and enables direct correlations between electrochemical performance and structural characteristics of cathode and anode materials. In situ XAS measurements are very demanding to the design of the experimental setup. We have developed a sample chamber that provides electrical connectivity and inert atmosphere for operating electrochemical cells and also accounts for x-ray interactions with the chamber and cell materials. The design of the sample chamber for in situ measurements is presented along with example XAS spectra from anode materials in operating pouch cells at the Zn and Sn K-edges measured in fluorescence and transmission modes, respectively.

Pelliccione, C. J.; Timofeeva, E. V.; Katsoudas, J. P.; Segre, C. U.

2014-12-01

282

Note: Sample chamber for in situ x-ray absorption spectroscopy studies of battery materials.  

PubMed

In situ x-ray absorption spectroscopy (XAS) provides element-specific characterization of both crystalline and amorphous phases and enables direct correlations between electrochemical performance and structural characteristics of cathode and anode materials. In situ XAS measurements are very demanding to the design of the experimental setup. We have developed a sample chamber that provides electrical connectivity and inert atmosphere for operating electrochemical cells and also accounts for x-ray interactions with the chamber and cell materials. The design of the sample chamber for in situ measurements is presented along with example XAS spectra from anode materials in operating pouch cells at the Zn and Sn K-edges measured in fluorescence and transmission modes, respectively. PMID:25554344

Pelliccione, C J; Timofeeva, E V; Katsoudas, J P; Segre, C U

2014-12-01

283

Equation of motion coupled cluster theory calculations of the X-ray emission spectroscopy of water  

NASA Astrophysics Data System (ADS)

The equation of motion coupled cluster theory including single and double excitations (EOM-CCSD) method is applied to study the X-ray emission spectroscopy of water. For the 1b1 orbital, a difference of about 0.7 eV is predicted between a tetrahedrally coordinated water molecule and a water molecule in which water molecules accepting hydrogen bonds are absent, and as a proton is dissociated emission from the 1b1 and 3a1 orbitals become closer in energy. The resonantly excited X-ray emission spectrum for the 4a1 orbital shows a red-shift in the bands and a reduction in intensity for the 3a1 band.

Besley, Nicholas A.

2012-07-01

284

Self-consistent absorption corrections for low-energy X-ray lines in energy-dispersive X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

Quantification of energy-dispersive X-ray spectra in transmission electron microscopy is often unreliable for X-ray lines of low energy, as they are subject to strong absorption and fluorescence corrections which will depend critically on both the sample thickness and the detector properties (take-off angle, detector material and type, thickness and cleanliness of any detector window). By using the method to vary the take-off angle between repeated measurements in energy-dispersive X-ray spectroscopy from the same region, an attempt has been made to study our ability to determine the depth of a buried epitaxial thin layer within a plan-view sample and to correctly assess the composition of specimens containing lighter elements. By using several different Monte Carlo simulation programs, the attenuation of the X-rays along their path towards the detector can be calculated and the predicted results can be compared to experimental measurements. Comparison of two different programs to experimental results has been made, for an InAs quantum well buried beneath a GaAs cap layer and a NiO thin film specimen.

Parri, M. C.; Walther, T.

2012-07-01

285

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

286

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

287

Inner-shell photoionization spectroscopy on deposited metal clusters using soft x-ray synchrotron radiation: an experimental setup.  

PubMed

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(19) deposited onto the natural oxide layer of a Si-wafer surface. PMID:20059169

Peters, S; Peredkov, S; Balkaya, B; Ferretti, N; Savci, A; Vollmer, A; Neeb, M; Eberhardt, W

2009-12-01

288

The Suzaku High Resolution X-Ray Spectrometer  

Microsoft Academic Search

The X-Ray Spectrometer (XRS) has been designed to provide the Suzaku Observatory with non-dispersive, high-resolution X-ray spectroscopy. As designed, the instrument covers the energy range 0.3 to 12keV, which encompasses the most diagnostically rich part of the X-ray band. The sensor consists of a 32-channel array of X-ray microcalorimeters, each with an energy resolution of about 6eV. The very low

Richard L. Kelley; Kazuhisa Mitsuda; Christine A. Allen; Petar Arsenovic; Michael D. Audley; Thomas G. Bialas; Kevin R. Boyce; Robert F. Boyle; Susan R. Breon; Gregory V. Brown; Jean Cottam; Michael J. Dipirro; Ryuichi Fujimoto; Tae Furusho; Keith C. Gendreau; Gene G. Gochar; Oscar Gonzalez; Masayuki Hirabayashi; Stephen S. Holt; Hajime Inoue; Manabu Ishida; Yoshitaka Ishisaki; Carol S. Jones; Ritva Keski-Kuha; Caroline A. Kilbourne; Dan McCammon; Umeyo Morita; S. Harvey Moseley; Brent Mott; Katsuhiro Narasaki; Yoshiaki Ogawara; Takaya Ohashi; Naomi Ota; John S. Panek; F. Scott Porter; Aristides Serlemitsos; Peter J. Shirron; Gary A. Sneiderman; Andrew E. Szymkowiak; Yoh Takei; June L. Tveekrem; Stephen M. Volz; Mikio Yamamoto; Noriko Y. Yamasaki

2007-01-01

289

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

290

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

291

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

292

Excited-state molecular structures captured by x-ray transient absorption spectroscopy : a decade and beyond.  

SciTech Connect

Transient molecular structures along chemical reaction pathways are important for predicting molecular reactivity, understanding reaction mechanisms, as well as controlling reaction pathways. During the past decade, X-ray transient absorption spectroscopy (XTA, or LITR-XAS, laser-initiated X-ray absorption spectroscopy), analogous to the commonly used optical transient absorption spectroscopy, has been developed. XTA uses a laser pulse to trigger a fundamental chemical process, and an X-ray pulse(s) to probe transient structures as a function of the time delay between the pump and probe pulses. Using X-ray pulses with high photon flux from synchrotron sources, transient electronic and molecular structures of metal complexes have been studied in disordered media from homogeneous solutions to heterogeneous solution-solid interfaces. Several examples from the studies at the Advanced Photon Source in Argonne National Laboratory are summarized, including excited-state metalloporphyrins, metal-to-ligand charge transfer (MLCT) states of transition metal complexes, and charge transfer states of metal complexes at the interface with semiconductor nanoparticles. Recent developments of the method are briefly described followed by a future prospective of XTA. It is envisioned that concurrent developments in X-ray free-electron lasers and synchrotron X-ray facilities as well as other table-top laser-driven femtosecond X-ray sources will make many breakthroughs and realise dreams of visualizing molecular movies and snapshots, which ultimately enable chemical reaction pathways to be controlled.

Chen, L. X.; Zhang, X.; Lockard, J. V.; Stickrath, A. B.; Attenkofer, K.; Jennings, G.; Liu, D.-J.; Northwestern Univ.

2010-03-02

293

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

294

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

295

Three-dimensional electron realm in VSe2 by soft-x-ray photoelectron spectroscopy: origin of charge-density waves.  

PubMed

The resolution of angle-resolved photoelectron spectroscopy (ARPES) in three-dimensional (3D) momentum k is fundamentally limited by ill defined surface-perpendicular wave vector k(perpendicular) associated with the finite photoelectron mean free path. Pushing ARPES into the soft-x-ray energy region sharpens the k(perpendicular) definition, allowing accurate electronic structure investigations in 3D materials. We apply soft-x-ray ARPES to explore the 3D electron realm in a paradigm transition metal dichalcogenide VSe2. Essential to break through the dramatic loss of the valence band photoexcitation cross section at soft-x-ray energies is the advanced photon flux performance of our synchrotron instrumentation. By virtue of the sharp 3D momentum definition, the soft-x-ray ARPES experimental band structure and Fermi surface of VSe2 show a textbook clarity. We identify pronounced 3D warping of the Fermi surface and show that its concomitant nesting acts as the precursor for the exotic 3D charge-density waves in VSe2. Our results demonstrate the immense potential of soft-x-ray ARPES to explore details of 3D electronic structure. PMID:23002761

Strocov, Vladimir N; Shi, Ming; Kobayashi, Masaki; Monney, Claude; Wang, Xiaoqiang; Krempasky, Juraj; Schmitt, Thorsten; Patthey, Luc; Berger, Helmuth; Blaha, Peter

2012-08-24

296

Use of X-Ray Absorption Spectroscopy to Monitor the Kinetics of Metal Sorption Reactions at the Soil/Water Interface  

E-print Network

Use of X-Ray Absorption Spectroscopy to Monitor the Kinetics of Metal Sorption Reactions on the surface coordination environment of Ni sorbed onto clays and aluminum oxides using X-ray absorption fine

Sparks, Donald L.

297

Investigation by laser induced breakdown spectroscopy, X-ray fluorescence and X-ray powder diffraction of the chemical composition of white clay ceramic tiles from Veliki Preslav  

NASA Astrophysics Data System (ADS)

The paper presents the results of the application of laser induced breakdown spectroscopy, X-ray fluorescence spectrometry, and X-ray powder diffraction in assessing the chemical and phase composition of white clay decorative ceramic tiles from the medieval archaeological site of Veliki Preslav, a Bulgarian capital in the period 893-972 AC, well-known for its original ceramic production. Numerous white clay ceramic tiles with highly varied decoration, produced for wall decoration of city's churches and palaces, were found during the archaeological excavations in the old capital. The examination of fourteen ceramic tiles discovered in one of the city's monasteries is aimed at characterization of the chemical profile of the white-clay decorative ceramics produced in Veliki Preslav. Combining different methods and comparing the obtained results provides complementary information regarding the white-clay ceramic production in Veliki Preslav and complete chemical characterization of the examined artefacts.

Blagoev, K.; Grozeva, M.; Malcheva, G.; Neykova, S.

2013-01-01

298

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

299

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

300

Ultraprecision motion control technique for high-resolution x-ray instrumentation  

SciTech Connect

With the availability of third-generation hard x-ray synchrotron radiation sources, such as the Advanced Photon Source (APS) at Argonne National Laboratory, x-ray inelastic scattering and x-ray nuclear resonant scattering provide powerful means for investigating the vibrational dynamics of a variety of materials and condensed matter systems. Novel high-resolution hard x-ray optics with meV energy resolution requires a compact positioning mechanism with 20--50-nrad angular resolution and stability. In this paper, the authors technical approach to this design challenge is presented. Sensitivity and stability test results are also discussed.

Shu, D.; Toellner, T. S.; Alp, E. E.

2000-07-17

301

High-resolution X-ray spectroscopy of T Tauri stars in the Taurus-Auriga complex  

NASA Astrophysics Data System (ADS)

Context: Differences have been reported between the X-ray emission of accreting and non-accreting stars. Some observations have suggested that accretion shocks could be responsible for part of the X-ray emission in classical T Tauri stars (CTTS). Aims: We present high-resolution X-ray spectroscopy for nine pre-main sequence stars in order to test the proposed spectroscopic differences between accreting and non-accreting pre-main sequence stars. Methods: We used X-ray spectroscopy from the XMM-Newton Reflection Grating Spectrometers and the EPIC instruments. We interpret the spectra using optically thin thermal models with variable abundances, together with an absorption column density. For BP Tau and AB Aur we derive electron densities from the O vii triplets. Results: Using the O vii/O viii count ratios as a diagnostic for cool plasma, we find that CTTS display a soft excess (with equivalent electron temperatures of ?2.5{-}3 MK) when compared with WTTS or zero-age main-sequence stars. Although the O vii triplet in BP Tau is consistent with a high electron density (3.4 × 1011 cm-3), we find low density for the accreting Herbig star AB Aur (ne < 1010 cm-3). The element abundances of accreting and non-accreting stars are similar. The Ne abundance is found to be high (4-6 times the Fe abundance) in all K and M-type stars. In contrast, for the three G-type stars (SU Aur, HD 283572, and HP Tau/G2), we find an enhanced Fe abundance (0.4-0.8 times solar photospheric values) compared to later-type stars. Conclusions: Adding the results from our sample to former high-resolution studies of T Tauri stars, we find a soft excess in all accreting stars, but in none of the non-accretors. On the other hand, high electron density and high Ne/Fe abundance ratios do not seem to be present in all accreting pre-main sequence stars.

Telleschi, A.; Güdel, M.; Briggs, K. R.; Audard, M.; Scelsi, L.

2007-06-01

302

The design and application of an in-laboratory diffraction-enhanced x-ray imaging instrument  

SciTech Connect

We describe the design and application of a new in-laboratory diffraction-enhanced x-ray imaging (DEXI) instrument that uses a nonsynchrotron, conventional x-ray source to image the internal structure of an object. In the work presented here, a human cadaveric thumb is used as a test-sample to demonstrate the imaging capability of our instrument. A 22 keV monochromatic x-ray beam is prepared using a mismatched, two-crystal monochromator; a silicon analyzer crystal is placed in a parallel crystal geometry with the monochromator allowing both diffraction-enhanced imaging and multiple-imaging radiography to be performed. The DEXI instrument was found to have an experimentally determined spatial resolution of 160{+-}7 {mu}m in the horizontal direction and 153{+-}7 {mu}m in the vertical direction. As applied to biomedical imaging, the DEXI instrument can detect soft tissues, such as tendons and other connective tissues, that are normally difficult or impossible to image via conventional x-ray techniques.

Nesch, Ivan; Fogarty, Daniel P.; Tzvetkov, Tochko; Reinhart, Benjamin; Walus, A. Charles [Nesch, LLC 9800 Connecticut Drive, Crown Point, Indiana 46307 (United States); Khelashvili, Gocha [Nesch, LLC 9800 Connecticut Drive, Crown Point, Indiana 46307 (United States); Department of Radiation Oncology, Rush University Medical Center, 500 S. Paulina St., Chicago, Illinois 60612 (United States); Muehleman, Carol [Department of Biochemistry, Rush Medical College, 1735 W. Harrison St., Chicago, Illinois 60612 (United States); Chapman, Dean [Department of Anatomy and Cell Biology, College of Medicine, B331 Life Sciences Building, 107 Wiggins Road, Saskatoon, Saskatchewan S7N5E5 (Canada)

2009-09-15

303

Spin Polarized Photoelectron Spectroscopy in the Soft X-Ray Regime  

Microsoft Academic Search

We performed a set of novel spin-polarized electron emission experiments from a polycrystalline iron film to explore these spectroscopies in the soft X-ray regime. The experiments include measurement of spin polarization of (i) valence band photoemission (SPPES) and (ii) the 2p and 3p core levels as well as the 2p3p3p, 2p3p3d and 2p3d3d Auger processes on and off the 2p-3d

Eyal Ellakim Shekel

1995-01-01

304

Characterization of chemically amplified resist for X-ray lithography by Fourier transform infrared spectroscopy  

Microsoft Academic Search

SU-8 resist was characterized for X-ray lithography from a plasma focus\\u000a source by studying its cross-linking process using Fourier transform\\u000a infrared (FT-IR) spectroscopy. The cross-linking process of the resist\\u000a during post-exposure bake (PEB) was accurately monitored using the\\u000a infrared absorption peaks at 862, 914, and 1128 cm(-1). Results showed\\u000a that the cross-linking of SU-8 was effectively completed at the exposure

T. L. Tan; D. Wong; P Lee; R. S. Rawat; S. Springham; A. Patran

2006-01-01

305

Slow dynamics of nanocomposite polymer aerogels as revealed by X-ray photocorrelation spectroscopy (XPCS)  

SciTech Connect

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, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Mijangos, Carmen [Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva, 3, 28006 Madrid (Spain)] [Instituto de Ciencia y Tecnología de Polímeros, ICTP-CSIC, Juan de la Cierva, 3, 28006 Madrid (Spain); Nogales, Aurora, E-mail: rhernandez@ictp.csic.es, E-mail: aurora.nogales@csic.es; Ezquerra, Tiberio A. [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain)] [Instituto de Estructura de la Materia, IEM-CSIC, Serrano 121, 28006 Madrid (Spain); Sprung, Michael [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)] [Petra III at DESY, Notkestr. 85, 22607 Hamburg (Germany)

2014-01-14

306

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

307

High energy resolution x-ray absorption spectroscopy study of uranium in varying valence states  

Microsoft Academic Search

A high energy resolution x-ray absorption near-edge structure (XANES) spectroscopy study on U4+ (UO2) , U5+ ([UO2Py5][KI2Py2]) , and U6+ [UO2(NO3)2(H2O)6] demonstrates the potential of this experimental technique for qualitative\\/semiqualitative and quantitative actinide speciation investigations. We observe a pre-edge feature with quadrupole nature in a UL3 edge partial fluorescence yield-XANES spectrum. This feature is a tool for characterizing the participation

T. Vitova; K. O. Kvashnina; G. Nocton; G. Sukharina; M. A. Denecke; S. M. Butorin; M. Mazzanti; R. Caciuffo; A. Soldatov; T. Behrends; H. Geckeis

2010-01-01

308

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

309

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

310

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

311

Assessment of nanocomposite photonic systems with the X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The chemical compositions of Ag-Er co-doped phosphate and silicate glasses were investigated with X-ray photoelectron spectroscopy with the purpose to identify the chemical state of silver. The analysis of the Ag 3d core lines show the presence of nanometer-sized silver particles in each of the annealed samples, even if these Ag 3d lines appear to be very different from each other. We explain these results as a different interaction of silver with the two glasses matrix, which leads to a different nucleation rate of the Ag clusters.

Minati, L.; Speranza, G.; Anderle, M.; Ferrari, M.; Chiasera, A.; Righini, G. C.

2007-05-01

312

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. PMID:20225071

George, Graham N.; Singh, Satya P.; Myers, Gary J.; Watson, Gene E.; Pickering, Ingrid J.

2013-01-01

313

Biological X-ray spectroscopy on 3rd generation synchrotron radiation sources  

NASA Astrophysics Data System (ADS)

Third generation synchrotron radiation sources such as the Advanced Light Source (ALS) at Lawrence Berkeley Laboratory deliver 1-2 orders of magnitude more monochromatic flux (and many orders of magnitude higher brightness) than previously available. This paper describes the ring and existing beamlines of the advanced light source, and plans for crystallography and elliptical wiggler stations are discussed. Using nickel metalloprotein spectra recorded at NSLS and SSRL as examples, this paper describes how the higher monochromatic flux available from the ALS will be used for biological soft X-ray spectroscopy.

Ralston, Corie Y.; Chen, Jie; Peng, Gang; George, Simon J.; van Elp, Jan; Cramer, Stephen P.

1995-02-01

314

Dispersive X-ray Spectroscopy Analysis of Porous beta-TCP Bioceramics after Implantation into Femur.  

PubMed

In this paper, energy dispersive X-ray spectroscopy and element ratio of implanted bioceramic, interface and rabbit femur when the bioceramic implanted into femur were measured by two different scan electron microscopy (SEM) EDXA modes. The changes of element ratio and components of materials and interface implanted into femur were compared. Thorough studies were made on the transformation of TCP from lifeless materials into living bones after implantation, by using SEM-EDXA, Raman spectra and infrared spectra. These results provided rich evidence for understanding biodegration and bone bonding mechanism of calcium phosphate bioceramics. PMID:12114995

Chen, Qin; Li, Shi-Pu; He, Ji-Ping; Yu, Nai-Teng; Zheng, Qi-Xin; Yan, Yu-Hua

1999-01-01

315

Hydrogenated carbon nanotubes: x-ray absorption spectroscopy and ab initio simulation analysis  

NASA Astrophysics Data System (ADS)

The paper presents the results of investigation of the chemical bond formation in hydrogenated single-walled carbon nanotubes using X-ray absorption spectroscopy. All measurements were performed with the use of synchrotron radiation at BESSY II. The C1s absorption spectra point to formation of covalent chemical bonding between the hydrogen and carbon atoms in H-SWNTs. The investigation of the H-SWNT local structure has been carried out on the basis of the semi-empirical PM6 method (MOPAC 2009) and Finite Difference method. The possibility of H-SWNTs dehydrogenation was also investigated.

Brzhezinskaya, M.; Yalovega, G.; Shmatko, V.; Klyushin, A.; Bogoslavskaya, E.; Krestinin, A.; Bashkin, I.

2013-04-01

316

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

317

Calorimetric Low-Temperature Detectors for X-Ray Spectroscopy on Trapped Highly-Charged Heavy Ions  

NASA Technical Reports Server (NTRS)

The application of Calorimetric Low-Temperature Detectors (CLTDs) has been proposed at the Heavy-Ion TRAP facility HITRAP which is currently being installed at the Helmholtz Research Center for Heavy Ion Research GSI. This cold ion trap setup will allow the investigation of X-rays from ions practically at rest, for which the excellent energy resolution of CLTDs can be used to its full advantage. However, the relatively low intensities at HITRAP demand larger solid angles and an optimized cryogenic setup. The influence of external magnetic fields has to be taken into account. CLTDs will also be a substantial part of the instrumental equipment at the future Facility for Antiproton and Heavy Ion Research (FAIR), for which a wide variety of high-precision X-ray spectroscopy experiments has been proposed. This contribution will give an overview on the chances and challenges for the application of CLTDs at HITRAP as well as perspectives for future experiments at the FAIR facility.

Kilbourne, Caroline; Kraft-Bermuth, S.; Andrianov, V.; Bleile, A.; Echler, A.; Egelhof, P.; Ilieva, S.; Kilbourne, C.; McCammon, D.

2012-01-01

318

Where Water Is Oxidized to Dioxygen: Structure of the Photosynthetic Mn(4)Ca Cluster From X-Ray Spectroscopy  

SciTech Connect

Light-driven oxidation of water to dioxygen in plants, algae, and cyanobacteria is catalyzed within photosystem II (PS II) by a Mn{sub 4}Ca cluster. Although the cluster has been studied by many different methods, its structure and mechanism have remained elusive. X-ray absorption and emission spectroscopy and extended X-ray absorption fine structure studies have been particularly useful in probing the electronic and geometric structures and the mechanism of the water oxidation reaction. Recent progress, reviewed here, includes polarized X-ray absorption spectroscopy measurements of PS II single crystals. Analysis of those results has constrained the Mn{sub 4}Ca cluster geometry to a set of three similar high-resolution structures. The structure of the cluster from the present study is unlike either the 3.0- or 3.5-{angstrom}-resolution X-ray structures or other previously proposed models. The differences between the models derived from X-ray spectroscopy and crystallography are predominantly because of damage to the Mn{sub 4}Ca cluster by X-rays under conditions used for the structure determination by X-ray crystallography. X-ray spectroscopy studies are also used for studying the changes in the structure of the Mn{sub 4}Ca catalytic center as it cycles through the five intermediate states known as the S{sub i} states (i = 0--4). The electronic structure of the Mn{sub 4}Ca cluster has been studied more recently using resonant inelastic X-ray scattering spectroscopy (RIXS), in addition to the earlier X-ray absorption and emission spectroscopy methods. These studies are revealing that the assignment of formal oxidation states is overly simplistic. A more accurate description should consider the charge density on the Mn atoms, which includes the covalency of the bonds and delocalization of the charge over the cluster. The geometric and electronic structures of the Mn{sub 4}Ca cluster in the S states derived from X-ray spectroscopy are leading to a detailed understanding of the mechanism of O-O bond formation during the photosynthetic water-splitting process.

Yano, J.; Yachandra, V.K.

2009-05-28

319

A high performance, low-noise 128-channel readout integrated circuit for instrumentation and X-ray applications  

Microsoft Academic Search

Indigo Operations, subdivision of FLIR Systems, has designed, fabricated, and tested a mixed-signal readout integrated circuit (ROIC), the ISC9717, for instrumentation and flat panel X-ray applications. This off-the-shelf, high performance, low-noise, 128-channel device is fully programmable with a multistage pipelined architecture and a 9 to 14-bit programmable A\\/D converter per channel, making it suitable for numerous instrumentation detector types, especially

Eric Beuville; Mark Belding; Adrienne Costello; Randy Hansen; Susan Petronio

2004-01-01

320

On the sensitivity of hard X-ray spectroscopies to the chemical state of Br.  

PubMed

The sensitivity of the 1s X-ray emission and high-energy-resolution fluorescence-detected X-ray absorption spectroscopies (XES and HERFD-XAS) to resolve the variations in the chemical state (electronic structure and local coordination) of Br has been investigated for a selected set of compounds including NaBrO3, NH4Br and C2H4Br2 (1,2-dibromoethane). For the Br K-edge XAS, employing the HERFD mode significantly increases the energy resolution, which demonstrates that with a crystal spectrometer used as a detector the absorption technique becomes a more powerful analytical tool. In the case of XES, the experimental results as well as the density functional theory (DFT) modeling both show that the chemical sensitivity of the main 1s diagram emission lines (K?1,2 and K?1,3) is rather limited. However, the valence-to-core (K?2) region of XES displays significant shape and intensity variations, as expected for transitions having the same final states as those of photoemission spectroscopy. The spectra are in good agreement with the molecular orbital description delivered by DFT calculations. Calculations for an extended series of Br compounds confirm that valence-to-core XES can serve as a probe for chemical analysis, and, being a hard X-ray photon-in/photon-out technique, it is particularly well-suited for in situ investigations of molecular transformations, even on the ultrafast time scales down to femtosecond time resolution. PMID:23719632

Bordage, Amélie; Pápai, Mátyás; Sas, Norbert S; Szlachetko, Jakub; Nachtegaal, Maarten; Vankó, György

2013-07-14

321

SIXS: X-Ray and Particle Instrument on BepiColombo  

NASA Astrophysics Data System (ADS)

The Solar Intensity X-ray and particle Spectrometer (SIXS) from the University of Helsinki, Finland [1] will fly on board the ESA's BepiColombo mission to determine the solar impact on the Hermean surface in the form of direct X-rays and energetic particles, which induce observable X-ray emission via interaction with the surface of the planet. Particles of concern here are highly energetic solar protons (1-30 MeV) and electrons (0.1 - 3 MeV), and the energy range of measured X-ray spectrum is 1-20 keV. The resulting fluorescence, measured by the Mercury Imaging X-ray Spectrometer (MIXS) from the University of Leicester, UK, [2] will provide detailed information about the elemental composition on the Mercury's surface. This article presents some design highlights of the SIXS sensor unit.

Huovelin, J.; Schmidt, W.; Genzer, M.; Lehti, J.; Vaijärvi, S.

2013-09-01

322

6 MeV storage ring dedicated to hard X-ray imaging and far-infrared spectroscopy  

Microsoft Academic Search

.  The tabletop storage ring, 6 MeV MIRRORCLE, is dedicated to hard X-ray imaging as well as far-infrared (FIR) spectroscopy.\\u000a In spite of low electron energy, the 6 MeV MIRRORCLE generates hard X-rays ranging from 10 keV up to its electron energy\\u000a and milliwatt order sub-millimetre range FIR rays. Bremsstrahlung is the mechanism for the hard X-ray generation. Images produced\\u000a with 11× geometrical magnification

M. M. Haque; A. Moon; T. Hirai; H. Yamada

2011-01-01

323

Core and Valence Excitations in Resonant X-ray Spectroscopy using Restricted Excitation Window Time-dependent Density Functional Theory  

SciTech Connect

We report simulations of X-ray absorption near edge structure (XANES), resonant inelastic X-ray scattering (RIXS) and 1D stimulated X-ray Raman spectroscopy (SXRS) signals of cysteine at the oxygen, nitrogen and sulfur K and L2,3 edges. The simulated XANES signals from the restricted window time-dependent density functional theory (REW-TDDFT) and the static exchange (STEX) method are compared with experiments, showing that REW-TDDFT is more accurate and computationally less expensive than STEX. Simulated RIXS and 1D SXRS signals from REW-TDDFT give some insights on the correlation of different excitations in the molecule.

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

2012-11-21

324

First results from the high-brightness x-ray spectroscopy beamline 9. 3.1 at ALS  

SciTech Connect

Beamline 9.3.1 at the Advanced Light Source (ALS) is a windowless beamline, covering the 1-6 keV photon-energy range. This beamline is designed to achieve the goal of high brightness at the sample for use in the X-ray Atomic and Molecular Spectroscopy (XAMS) science, surface and interface science, biology, and x-ray optical development programs at ALS. X-ray absorption and time of flight photoemission measurements in 2 - 5 keV photon energy along with the flux, resolution, spot size and stability of the beamline will be discussed. Prospects for future XAMS measurements will also be presented.

Ng, W.; Jones, G.; Perera, R.C.C.

1995-10-01

325

Electronic structure of individual hybrid colloid particles studied by near-edge X-ray absorption fine structure (NEXAFS) spectroscopy in the X-ray microscope.  

PubMed

The electronic structure of individual hybrid particles was studied by nanoscale near-edge X-ray absorption spectromicroscopy. The colloidal particles consist of a solid polystyrene core and a cross-linked poly-N-(isopropylacrylamide) shell with embedded crystalline titanium dioxide (TiO(2)) nanoparticles (d = 6 ± 3 nm). The TiO(2) particles are generated in the carrier network by a sol-gel process at room temperature. The hybrid particles were imaged with photon energy steps of 0.1 eV in their hydrated environment with a cryo transmission X-ray microscope (TXM) at the Ti L(2,3)-edge. By analyzing the image stacks, the obtained near-edge X-ray absorption fine structure (NEXAFS) spectra of our individual hybrid particles show clearly that our synthesis generates TiO(2) in the anastase phase. Additionally, our spectromicroscopy method permits the determination of the density distribution of TiO(2) in single carrier particles. Therefore, NEXAFS spectroscopy combined with TXM presents a unique method to get in-depth insight into the electronic structure of hybrid materials. PMID:23360082

Henzler, Katja; Guttmann, Peter; Lu, Yan; Polzer, Frank; Schneider, Gerd; Ballauff, Matthias

2013-02-13

326

X-ray crystal spectroscopy with stationary-state single-crystal utilizing Laue diffraction  

Microsoft Academic Search

A new type of x-ray crystal spectrometry has been designed to characterize a hard x-ray spectrum of each pulse emission from a laser-induced plasma x-ray source. Utilizing the Laue diffraction and a two-dimensional detector, it makes possible the measurement of diffracted monochromatic x rays without any time difference using a single crystal in a stationary state. Thus, a hard x-ray

Kazumasa Honda; Tadayuki Ohchi; Isao Kojima; Shigeki Hayashi

2001-01-01

327

Advances in Time Resolved X-ray Excited Optical Luminescence Instrumentation at the Canadian Light Source  

SciTech Connect

Measurement of the optical emission properties of samples excited by x-rays can be used to study defect states in crystals and the optical properties of nanostructured materials. Changes in the intensities, wavelengths and lifetimes of the optical emission can occur when specific core level electrons are excited using tuneable light from a synchrotron light source. At the Canadian Light Source (CLS), collaboration between the user community, the experimental facilities group and the accelerator division has resulted in improved capabilities in the acquisition of Time Resolved XEOL (TRXEOL) data. Using a streak camera, the optical luminescence decay curves from samples excited with 35 ps long synchrotron pulses have been obtained. The streak tube is operated in single sweep mode and is triggered by the 500 MHz RF signal, which has been resynchronized to the orbit clock frequency giving a highly stable trigger pulse. A transverse kicker system is used to improve bunch purity from 10{sup 2} to 10{sup 6}. The decay curves of the XEOL of nanostructured ZnO and a high pressure form of SiO{sub 2} have been measured and demonstrate the unique capabilities of this instrumentation.

Regier, T. Z.; Vogt, J. M. [Canadian Light Source, Inc., 101 Perimeter Road, Saskatoon, Saskatchewan (Canada); Sammynaiken, R. [Sasakatchewan Structural Science Centre, 110 Science Place, Saskatoon, Saskatchewan (Canada); Sham, T. K. [Department of Chemistry, The University of Western Ontario, 1151 Richmond Street, London, Ontario (Canada)

2010-06-23

328

Structure and Composition of Cu Doped CdSe Nanocrystals Using Soft X-ray Absorption Spectroscopy  

Microsoft Academic Search

The local structure and composition of Cu ions dispersed in CdSe nanocrystals is examined using soft x-ray absorption near edge spectroscopy (XANES). Using Cu L-edge XANES and X-ray photoelectron measurements (XPS), we find that the Cu ions exist in the Cu(I) oxidation state. We also find that the observed Cu L-edge XANES signal is directly proportional to the molar percent

Robert W. Meulenberg; Tony van Buuren; Khalid M. Hanif; Trevor M. Willey; Geoffrey F. Strouse; Louis J. Terminello

2004-01-01

329

X-ray spectroscopy reveals high symmetry and electronic shell structure of transition-metal-doped silicon clusters  

Microsoft Academic Search

Size-selected cationic transition-metal-doped silicon clusters have been studied with x-ray absorption spectroscopy at the transition-metal L2,3 edges to investigate the local electronic structure of the dopant atoms. For VSi16+ , the x-ray absorption spectrum is dominated by sharp transitions which directly reveal the formation of a highly symmetric silicon cage around the vanadium atom. In spite of their different number

J. T. Lau; K. Hirsch; Ph. Klar; A. Langenberg; F. Lofink; R. Richter; J. Rittmann; M. Vogel; V. Zamudio-Bayer; T. Möller; B. V. Issendorff

2009-01-01

330

Structural properties of the glass system As-Se-S studied by x-ray absorption spectroscopy  

Microsoft Academic Search

The structural properties of As-Se-S glass system were investigated by x-ray absorption spectroscopy (XANES and EXAFS) using synchrotron radiation. A preliminary characterization by x-ray powder diffraction, differential scanning calorimetric and thermogravimetric measurements was also carried out. The changes in glass transition temperature (Tg) and glass decomposition temperature (Td) associated with glass compositions indicate that sulfur contributes to the instability of

Jinn-Lung Wang; Jyi-Ching Tsai; Chia-Tung Liu; Ponnusamy Nachimuthu; Ling-Yun Jang; Ru-Gan Liu; Jin-Ming Chen

2000-01-01

331

Single-State Electronic Structure Measurements Using Time-Resolved X-Ray Laser Induced Photoelectron Spectroscopy  

Microsoft Academic Search

We demonstrate single-shot x-ray laser induced time-of-flight photoelectron spectroscopy on semiconductor and metal surfaces with picosecond time resolution. The LLNL COMET compact tabletop x-ray laser source provides the necessary high photon flux (>10¹²\\/pulse), monochromaticity, picosecond pulse duration, and coherence for probing ultrafast changes in the city, chemical and electronic structure of these materials. Static valence band and shallow core-level photoemission

A J Nelson; J Dunn; T van Buuren

2004-01-01

332

X-ray spectroscopy of a thin foil plasma produced by a short-pulse high-intensity laser  

Microsoft Academic Search

High density and temperature plasmas have been generated by irradiating thin foils of various elements with a high-energy subpicosecond laser pulse. The X-ray emission duration was studied by time-resolved X-ray spectroscopy. Frequency domain interferometry provided a measurement of the hydrodynamic expansion of the back of the foil as a function of time. The effect of longitudinal temperature gradients, i.e., gradients

P. Audebert; V. Nagels; J. P. Geindre; F. Dorchies; O. Peyrusse; S. Gary; F. Girard; R. Shepherd; J. C. Gauthier; C. Chenais-Popovics

2003-01-01

333

Raman and Mossbauer Spectroscopy and X-ray Diffractometry Studies on Quenched Copper-Ferri-Aluminates.  

PubMed

Four spinel ferrite compositions of the CuAlxFe2-xO4, x = 0.0, 0.2, 0.4, 0.6, system prepared by usual double-sintering ceramic route and quenched (rapid thermal cooling) from final sintering temperature (1373 K) to liquid nitrogen temperature (80 K) were investigated by employing X-ray powder diffractometry, (57)Fe Mossbauer spectroscopy, and micro-Raman spectroscopy at 300 K. The Raman spectra collected in the wavenumber range of 100-1000 cm(-1) were analyzed in a systematic manner and showed five predicted modes for the spinel structure and splitting of A1g Raman mode into two/three energy values, attributed to peaks belonging to each ion (Cu(2+), Fe(3+), and Al(3+)) in the tetrahedral positions. The suppression of lower-frequency peaks was explained on the basis of weakening in magnetic coupling and reduction in ferrimagnetic behavior as well as increase in stress induced by square bond formation on Al(3+) substitution. The enhancement in intensity, random variation of line width, and blue shift for highest frequency peak corresponding to A1g mode were observed. The ferric ion (Fe(3+)) concentration for different compositions determined from Raman spectral analysis agrees well with that deduced by means of X-ray diffraction line-intensity calculations and Mossbauer spectral analysis. An attempt was made to determine elastic and thermodynamic properties from Raman spectral analysis and elastic constants from cation distribution. PMID:25594232

Modi, Kunal B; Raval, Pooja Y; Shah, Suraj J; Kathad, Chetan R; Dulera, Sonal V; Popat, Mansi V; Zankat, Kiritsinh B; Saija, Kiran G; Pathak, Tushar K; Vasoya, Nimish H; Lakhani, Vinay K; Chandra, Usha; Jha, Prafulla K

2015-02-16

334

Near-Edge X-Ray Absorption Fine Structure Spectroscopy of Diamondoid Thiol Monolayers on Gold  

SciTech Connect

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

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

2009-05-26

335

X-ray photoelectron spectroscopy characterization of the {omega} phase in water quenched Ti-5553 alloy  

SciTech Connect

X-ray photoelectron spectroscopy was used to investigate the {omega} phase in water quenched Ti-5553 alloy with a nominal composition of Ti-5Al-5V-5Mo-3Cr (wt.%), and the {omega} and the {beta} phase were distinguished by deconvoluting the XPS spectra of Al2p, V2p and Cr2p core level regions. In addition, it is found that the binding energy of core level electron of alloying elements shifts comparing with that of pure metals, and the fact was interpreted by charge redistribution model. X-ray photoelectron spectroscopy technique could be used to characterize the nano-scale {omega} phase in {beta} alloys. - Highlights: Black-Right-Pointing-Pointer We characterize the {omega} phase in Ti-5553 alloy by XPS. Black-Right-Pointing-Pointer Binding energy of Al2p, V2p and Cr2p electron are different in the {omega} and {beta} phase. Black-Right-Pointing-Pointer Structural difference leads to the binding energy gap.

Qin, Dongyang, E-mail: qindongyang19831205@126.com [State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xi'an 710049 (China) [State Key Laboratory for Mechanical Behavior of Materials, Xian Jiaotong University, Xi'an 710049 (China); Northwest Institute for Non-ferrous Metal Research, Xi'an 710016 (China); Lu, Yafeng [Northwest Institute for Non-ferrous Metal Research, Xi'an 710016 (China)] [Northwest Institute for Non-ferrous Metal Research, Xi'an 710016 (China); Zhang, Kong; Liu, Qian [The State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China)] [The State Key Laboratory of High Performance Ceramics and Superfine Microstructure, Shanghai Institute of Ceramics, Chinese Academy of Sciences, Shanghai 200050 (China); Zhou, Lian [Northwest Institute for Non-ferrous Metal Research, Xi'an 710016 (China)] [Northwest Institute for Non-ferrous Metal Research, Xi'an 710016 (China)

2012-11-15

336

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

SciTech Connect

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

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

2007-11-27

337

Evolution of Silver Nanoparticles in the Rat Lung Investigated by X-ray Absorption Spectroscopy.  

PubMed

Following a 6-h inhalation exposure to aerosolized 20 and 110 nm diameter silver nanoparticles, lung tissues from rats were investigated with X-ray absorption spectroscopy, which can identify the chemical state of silver species. Lung tissues were processed immediately after sacrifice of the animals at 0, 1, 3, and 7 days post exposure and the samples were stored in an inert and low-temperature environment until measured. We found that it is critical to follow a proper processing, storage and measurement protocol; otherwise only silver oxides are detected after inhalation even for the larger nanoparticles. The results of X-ray absorption spectroscopy measurements taken in air at 85 K suggest that the dominating silver species in all the postexposure lung tissues were metallic silver, not silver oxide, or solvated silver cations. The results further indicate that the silver nanoparticles in the tissues were transformed from the original nanoparticles to other forms of metallic silver nanomaterials and the rate of this transformation depended on the size of the original nanoparticles. We found that 20 nm diameter silver nanoparticles were significantly modified after aerosolization and 6-h inhalation/deposition, whereas larger, 110 nm diameter nanoparticles were largely unchanged. Over the seven-day postexposure period the smaller 20 nm silver nanoparticles underwent less change in the lung tissue than the larger 110 nm silver nanoparticles. In contrast, silica-coated gold nanoparticles did not undergo any modification processes and remained as the initial nanoparticles throughout the 7-day study period. PMID:25517690

Davidson, R Andrew; Anderson, Donald S; Van Winkle, Laura S; Pinkerton, Kent E; Guo, T

2015-01-15

338

Temperature determination of resonantly excited plasmonic branched gold nanoparticles by X-ray absorption spectroscopy.  

PubMed

The fields of bioscience and nanomedicine demand precise thermometry for nanoparticle heat characterization down to the nanoscale regime. Since current methods often use indirect and less accurate techniques to determine the nanoparticle temperature, there is a pressing need for a direct and reliable element-specific method. In-situ extended X-ray absorption fine structure (EXAFS) spectroscopy is used to determine the thermo-optical properties of plasmonic branched gold nanoparticles upon resonant laser illumination. With EXAFS, the direct determination of the nanoparticle temperature increase upon laser illumination is possible via the thermal influence on the gold lattice parameters. More specifically, using the change of the Debye-Waller term representing the lattice disorder, the temperature increase is selectively measured within the plasmonic branched nanoparticles upon resonant laser illumination. In addition, the signal intensity shows that the nanoparticle concentration in the beam more than doubles during laser illumination, thereby demonstrating that photothermal heating is a dynamic process. A comparable temperature increase is measured in the nanoparticle suspension using a thermocouple. This good correspondence between the temperature at the level of the nanoparticle and at the level of the suspension points to an efficient heat transfer between the nanoparticle and the surrounding medium, thus confirming the potential of branched gold nanoparticles for hyperthermia applications. This work demonstrates that X-ray absorption spectroscopy-based nanothermometry could be a valuable tool in the fast-growing number of applications of plasmonic nanoparticles, particularly in life sciences and medicine. PMID:21744495

Van de Broek, Bieke; Grandjean, Didier; Trekker, Jesse; Ye, Jian; Verstreken, Kris; Maes, Guido; Borghs, Gustaaf; Nikitenko, Sergey; Lagae, Liesbet; Bartic, Carmen; Temst, Kristiaan; Van Bael, Margriet J

2011-09-01

339

X-Ray Fluorescence and Laser-Induced Breakdown Spectroscopy analysis of Roman silver denarii  

NASA Astrophysics Data System (ADS)

In this paper we present the results of a study performed on a large collection of silver Roman republican denarii, encompassing about two centuries of history. The joint use of Laser-Induced Breakdown Spectroscopy (LIBS) and X-Ray Fluorescence (XRF) spectroscopy allowed for an accurate determination of the coins' elemental composition; the measurements, performed mostly in situ at the 'Monetiere' in Florence, revealed a striking connection between the 'quality' of the silver alloy and some crucial contemporary events. This finding was used to classify a group of denarii whose dating was otherwise impossible. The comparison with other contemporary denarii disproves a recent theory on the origin of the so called 'serrated' denarii (denarii showing notched chisel marks on the edge of the coin).

Pardini, L.; El Hassan, A.; Ferretti, M.; Foresta, A.; Legnaioli, S.; Lorenzetti, G.; Nebbia, E.; Catalli, F.; Harith, M. A.; Diaz Pace, D.; Anabitarte Garcia, F.; Scuotto, M.; Palleschi, V.

2012-08-01

340

Energy Dispersive X-Ray and Electrochemical Impedance Spectroscopies for Performance and Corrosion Analysis of PEMWEs  

NASA Astrophysics Data System (ADS)

Proton exchange membrane water electrolyzers (PEMWEs) are a promising energy storage technology due to their high efficiency, compact design, and ability to be used in a renewable energy system. Before they are able to make a large commercial impact, there are several hurdles facing the technology today. Two powerful techniques for both in-situ and ex- situ characterizations to improve upon their performance and better understand their corrosion are electrochemical impedance spectroscopy and energy dispersive x-ray spectroscopy, respectively. In this paper, the authors use both methods in order to characterize the anode gas diffusion layer (GDL) in a PEMWE cell and better understand the corrosion that occurs in the oxygen electrode during electrolysis.

Steen, S. M., Iii; Zhang, F.-Y.

2014-11-01

341

Uses of Auger and x ray photoelectron spectroscopy in the study of adhesion and friction  

NASA Technical Reports Server (NTRS)

Three studies are described characterizing the possible contributions of surface science to tribology. These include surface contamination formed by the interaction of a surface with the environment, contaminants obtained with diffusion of compounds, and surface chemical changes resulting from selective thermal evaporation. Surface analytical tools such as Auger electron spectroscopy (AES) and x ray photoelectron spectroscopy (XPS) incorporated directly into adhesion and friction systems are primarily used to define the nature of tribological surfaces before and after tribological experimentation and to characterize the mechanism of solid-to-solid interaction. Emphasis is on fundamental studies involving the role of surfaces in controlling the adhesion and friction properties of materials emerging as a result of the surface analyses. The materials which were studied include metals and ceramics such as elemental metals, amorphous alloys (metallic glasses), and silicon-based ceramics.

Miyoshi, Kazuhisa

1990-01-01

342

Lunar sample analysis. [X-ray photoemission and Auger spectroscopy of lunar glass  

NASA Technical Reports Server (NTRS)

The surface composition of two samples from the highly shocked, glass-coated lunar basalt (12054) and from four glass-coated fragments from the 1-2 mm (14161) fines were examined by X-ray photoemission spectroscopy to determine whether the agglutination process itself is responsible for the difference between their surface and bulk compositions. Auger electron spectroscopy of glass balls from the 15425 and 74001 fines were analyzed to understand the nature, extent, and behavior of volatile phases associated with lunar volcanism. Initial results indicate that (1) volatiles, in the outer few atomic layers sampled, vary considerably from ball to ball; (2) variability over the surface of individual balls is smaller; (3) the dominant volatiles on the balls are S and Zn; and (4) other volatiles commonly observed are P, Cl, and K.

Housley, R. M.; Grant, R. W.; Cirlin, E. H.

1979-01-01

343

An XPS /ESCA/ study of lunar surface alteration profiles. [X ray Photoemission Spectroscopy  

NASA Technical Reports Server (NTRS)

We describe several important potential applications of surface analyses in planetology, and discuss some fundamental questions pertinent to the use of X-ray photoemission spectroscopy XPS or Auger electron spectroscopy AES to study complex powder samples. It appears that in addition to specific studies of surface chemistry, XPS may be able to provide useful major element analyses for all elements except hydrogen and perhaps helium and lithium. We provide data on the chemical changes associated with sputtering of a synthetic lunar glass. The surface is depleted in Si and enriched in Ca and Ti with Fe remaining nearly constant in parallel with changes observed during thermal volatilization. No Fe reduction was observed. Composition profiles obtained by sputtering 15301 fines suggest that surface alterations and reduced Fe are confined largely to depths of a few 100 A.

Housley, R. M.; Grant, R. W.

1977-01-01

344

Electronic structure measurements of metal-organic solar cell dyes using x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

The focus of this thesis is twofold: to report the results of X-ray absorption studies of metal-organic dye molecules for dye-sensitized solar cells and to provide a basic training manual on X-ray absorption spectroscopy techniques and data analysis. The purpose of our research on solar cell dyes is to work toward an understanding of the factors influencing the electronic structure of the dye: the choice of the metal, its oxidation state, ligands, and cage structure. First we study the effect of replacing Ru in several common dye structures by Fe. First-principles calculations and X-ray absorption spectroscopy at the C 1s and N 1s edges are combined to investigate transition metal dyes in octahedral and square planar N cages. Octahedral molecules are found to have a downward shift in the N 1s-to-pi* transition energy and an upward shift in C 1s-to-pi* transition energy when Ru is replaced by Fe, explained by an extra transfer of negative charge from Fe to the N ligands compared to Ru. For the square planar molecules, the behavior is more complex because of the influence of axial ligands and oxidation state. Next the crystal field parameters for a series of phthalocyanine and porphyrins dyes are systematically determined using density functional calculations and atomic multiplet calculations with polarization-dependent X-ray absorption spectra. The polarization dependence of the spectra provides information on orbital symmetries which ensures the determination of the crystal field parameters is unique. A uniform downward scaling of the calculated crystal field parameters by 5-30% is found to be necessary to best fit the spectra. This work is a part of the ongoing effort to design and test new solar cell dyes. Replacing the rare metal Ru with abundant metals like Fe would be a significant advance for dye-sensitized solar cells. Understanding the effects of changing the metal centers in these dyes in terms of optical absorption, charge transfer, and electronic structure enables the systematic design of new dyes using less expensive materials.

Johnson, Phillip S.

345

Planetary and satellite x ray spectroscopy: A new window on solid-body composition by remote sensing  

NASA Technical Reports Server (NTRS)

The rings and most of the satellites of the outer planets orbit within the radiation belts of their parent bodies. This is an environment with intense fluxes of energetic electrons. As a result, these objects are strong emitters of X-rays. The characteristic X-ray lines from these bodies depend on atomic composition, but they are not sensitive to how the material is arranged in compounds or mixtures. X-ray fluorescence spectral analysis has demonstrated its unique value in the laboratory as a qualitative and quantitative analysis tool. This technique has yet to be fully exploited in a planetary instrument for remote sensing. The characteristic X-ray emissions provide atomic relative abundances. These results are complementary to the molecular composition information obtained from IR, visible, and UV emission spectra. The atomic relative abundances are crucial to understanding the formation and evolution of these bodies. They are also crucial to the proper interpretation of the molecular composition results from the other sensors. The intensities of the characteristic X-ray emissions are sufficiently strong to be measured with an instrument of modest size. Recent developments in X-ray detector technologies and electronic miniaturization have made possible space-flight X-ray imaging and nonimaging spectrometers of high sensitivity and excellent energy resolution that are rugged enough to survive long-duration space missions. Depending on the application, such instruments are capable of resolving elemental abundances of elements from carbon through iron. At the same time, by measuring the bremsstrahlung intensity and energy spectrum, the characteristics of the source electron flux can be determined. We will discuss these concepts, including estimated source strengths, and will describe a small instrument capable of providing this unique channel of information for future planetary missions. We propose to build this instrument using innovative electronics packaging methods to minimize size and weight.

Chenette, D. L.; Wolcott, R. W.; Selesnick, R. S.

1993-01-01

346

Atomic data needs for X-ray spectroscopy of photo-ionised plasmas  

SciTech Connect

High-resolution X-ray spectroscopy of Active Galactic Nuclei has become possible thanks to the launch of XMM-Newton and Chandra with their grating spectrometers, and will be explored further after the expected launch of ASTRO-E2 with its XRS detector. In several AGN the X-ray spectra show the signatures of on outflowing, photo-ionised wind. Also several X-ray binaries show a similar imprint of a photo-ionised gas. The clearest signatures are formed by the broad range of absorption lines, mostly from the ground states of a wide range of ionisation states of the abundant elements. In addition to absorption lines due to the valence electrons, the spectra show many inner-shell absorption lines. Examples are the K-shell transitions of the most abundant metal, oxygen, in the 19-23 A band, and 2p-3d transitions of lowly ionised iron in the 15-17 A region. These transitions have an extremely important diagnostic value, as other transitions of the same ions frequently occur in the unobservable extreme ultraviolet. Several of these inner-shell transitions, however, lack accurate experimental or theoretical wavelengths, which makes the spectral analysis complicated and ambiguous. This is even more the case for transitions from metastable levels, which can be used as density diagnostics. Finally, attention is paid to the role of atomic data in the photo-ionisation equilibrium calculations. Uncertainties in for example dielectronic recombination rates cause large uncertainties in the predicted absorption line strengths.

Kaastra, Jelle S. [SRON, Sorbonnelaan 2, 3584 CA Utrecht (Netherlands)

2005-05-27

347

Characterization and speciation of mercury-bearing mine wastes using X-ray absorption spectroscopy  

USGS Publications Warehouse

Mining of mercury deposits located in the California Coast Range has resulted in the release of mercury to the local environment and water supplies. The solubility, transport, and potential bioavailability of mercury are controlled by its chemical speciation, which can be directly determined for samples with total mercury concentrations greater than 100 mg kg-1 (ppm) using X-ray absorption spectroscopy (XAS). This technique has the additional benefits of being non-destructive to the sample, element-specific, relatively sensitive at low concentrations, and requiring minimal sample preparation. In this study, Hg L(III)-edge extended X-ray absorption fine structure (EXAFS) spectra were collected for several mercury mine tailings (calcines) in the California Coast Range. Total mercury concentrations of samples analyzed ranged from 230 to 1060 ppm. Speciation data (mercury phases present and relative abundances) were obtained by comparing the spectra from heterogeneous, roasted (calcined) mine tailings samples with a spectral database of mercury minerals and sorbed mercury complexes. Speciation analyses were also conducted on known mixtures of pure mercury minerals in order to assess the quantitative accuracy of the technique. While some calcine samples were found to consist exclusively of mercuric sulfide, others contain additional, more soluble mercury phases, indicating a greater potential for the release of mercury into solution. Also, a correlation was observed between samples from hot-spring mercury deposits, in which chloride levels are elevated, and the presence of mercury-chloride species as detected by the speciation analysis. The speciation results demonstrate the ability of XAS to identify multiple mercury phases in a heterogeneous sample, with a quantitative accuracy of ??25% for the mercury-containing phases considered. Use of this technique, in conjunction with standard microanalytical techniques such as X-ray diffraction and electron probe microanalysis, is beneficial in the prioritization and remediation of mercury-contaminated mine sites. (C) 2000 Elsevier Science B.V.

Kim, C.S.; Brown, G.E., Jr.; Rytuba, J.J.

2000-01-01

348

Charging phenomena in dielectric/semiconductor heterostructures during x-ray photoelectron spectroscopy measurements  

NASA Astrophysics Data System (ADS)

The determination of the valence band offset (VBO) by x-ray photoelectron spectroscopy (XPS) is commonly performed using the so-called Kraut's method that was developed for VBO determination in semiconductor/semiconductor heterojunctions. Although the physical model, which is the basis of the method, can be safely extended to dielectric/semiconductor (D/S) heterojunctions, in these systems a careful evaluation of the experimental results is necessary due to the differential charging phenomena originating at D/S interface during x-ray bombardment. As a consequence, precise determination of the VBO requires an accurate calibration of the energy scale in order to remove artifacts induced by the progressive charging of the oxide during the XPS measurement. In this work a detailed analysis of the band alignment between e-beam evaporated amorphous HfO2 films and Si substrates is reported. The HfO2/Si heterojunction was selected as a prototype for this study since HfO2 based dielectrics have already been implemented as gate dielectrics in real devices and have been the subject of a wide number of publications providing controversial results in terms of VBO values. A clear dependence of the binding energy of the Hf 4f and O 1s core lines on the thickness of the HfO2 film is identified. The time evolution of these signals indicates that different steady states are reached after prolonged x-ray bombardment depending on the thickness of the HfO2 films. On the basis of the original work of Iwata et al. [J. App. Phys. 79, 6653 (1996)], a rigorous method to remove these artifacts and empirically determine the real band offsets in D/S heterojunctions is proposed and validated by comparison with internal photoemission and photoconductivity data obtained on the same set of samples.

Perego, M.; Seguini, G.

2011-09-01

349

X-ray reflection spectroscopy of the HfO2/SiO2/Si system in the region of the O-K absorption edge  

E-print Network

1 X-ray reflection spectroscopy of the HfO2/SiO2/Si system in the region of the O-K absorption edge Keywords : 405 Reflection spec.; 541 X-ray absorption; 96 Dielectrics; 354 Oxides PACS : Reflection spectra, 78.40.nq; X-ray reflectometry, 61.10.Kw; Dielectric materials, 77.84.ns; Dielectric properties

Boyer, Edmond

350

Micro-x-ray fluorescence, micro-x-ray absorption spectroscopy, and micro-x-ray diffraction investigation of lead speciation after the addition of different phosphorus amendments to a smelter-contaminated soil.  

PubMed

The stabilization of Pb on additions of P to contaminated soils and mine spoil materials has been well documented. It is clear from the literature that different P sources result in different efficacies of Pb stabilization in the same contaminated material. We hypothesized that the differences in the efficacy of Pb stabilization in contaminated soils on fluid or granular P amendment addition is due to different P reaction processes in and around fertilizer granules and fluid droplets. We used a combination of several synchrotron-based techniques (i.e., spatially resolved micro-X-ray fluorescence, micro-X-ray absorption near-edge structure spectroscopy, and micro-X-ray diffraction) to speciate Pb at two incubation times in a smelter-contaminated soil on addition of several fluid and granular P amendments. The results indicated that the Pb phosphate mineral plumbogummite was an intermediate phase of pyromorphite formation. Additionally, all fluid and granular P sources were able to induce Pb phosphate formation, but fluid phosphoric acid (PA) was the most effective with time and distance from the treatment. Granular phosphate rock and triple super phosphate (TSP) amendments reacted to generate Pb phosphate minerals, with TSP being more effective at greater distances from the point of application. As a result, PA and TSP were the most effective P amendments at inducing Pb phosphate formation, but caution needs to be exercised when adding large amounts of soluble P to the environment. PMID:25602650

Baker, Lucas R; Pierzynski, Gary M; Hettiarachchi, Ganga M; Scheckel, Kirk G; Newville, Matthew

2014-03-01

351

Nuclear resonant x-ray spectroscopy of (Mg,Fe)SiO{sub 3} orthoenstatites.  

SciTech Connect

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,{sup 57}Fe)SiO{sub 3}, 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{sub 3}. The Debye sound velocities were determined from the low-energy region of the partial phonon density of states (PDOS). With known density and bulk modulus, the shear modulus, compressional and shear wave velocities have been computed. The sound velocities obtained from NRIXS are in good agreement with sound velocities obtained using Brillouin spectroscopy and ultrasonic methods for similar compositions. An important advantage of NRIXS is access to additional thermodynamic information, such as the average force constant, mean-square displacement, obtained from the PDOS. We discuss the contribution of the vibrational spectra to these quantities. In addition to the PDOS, the electronic environment of the iron sites in (Mg{sub 0.87}{sup 57}Fe{sub 0.13})SiO{sub 3} orthoenstatite was determined using {sup 57}Fe SMS and conventional Moessbauer spectroscopy. Evaluation of the Moessbauer spectra reveals two distinct iron sites, which are well distinguished by their hyperfine fields. The minority and majority sites are consistent with high-spin Fe{sup 2+} in the M1 and M2 sites, respectively.

Jackson, J. M.; Hamecher, E. A.; Sturhahn, W.; X-Ray Science Division; California Inst. of Tech.

2009-05-01

352

A Suborbital Payload for Soft X-ray Spectroscopy of Extended Sources  

NASA Astrophysics Data System (ADS)

This thesis details the intent, design and results of an X-ray suborbital rocket payload whose scientific target was the Cygnus Loop Supernova Remnant. The payload consists of wire grid collimators, off-plane gratings arrays and gaseous electron multiplier (GEM) detectors. The system was designed for measurements in the 17-107 Å bandpass with a resolution up to ? 60 (?=??). This instrument was christened the Extended X-ray Off-plane Spectrometer (EXOS) and was launched on a Terrier-Black Brant rocket on November 13th, 2009 from White Sands Missile Range and obtained 340 seconds of useable scientific data. The emission is dominated by O VII and O VIII, including the He-like O VII triplet at ?22 Å. Another feature at ?45 Å is composed primarily of Si XI and Si XII. The best-fit model to this spectrum is an equilibrium plasma model at a temperature of log(T) = 6.4 (0.23 keV).

Oakley, Phillip Henry Howard

353

Americium characterization by X-ray fluorescence and absorption spectroscopy in plutonium uranium mixed oxide  

NASA Astrophysics Data System (ADS)

Plutonium uranium mixed oxide (MOX) fuels are currently used in nuclear reactors. The actinides in these fuels need to be analyzed after irradiation for assessing their behaviour with regard to their environment and the coolant. In this work the study of the atomic structure and next-neighbour environment of Am in the (Pu,U)O2 lattice in an irradiated (60 MW d kg-1) MOX sample was performed employing micro-X-ray fluorescence (µ-XRF) and micro-X-ray absorption fine structure (µ-XAFS) spectroscopy. The chemical bonds, valences and stoichiometry of Am (˜0.66 wt%) are determined from the experimental data gained for the irradiated fuel material examined in its peripheral zone (rim) of the fuel. In the irradiated sample Am builds up as Am3+ species within an [AmO8]13- coordination environment (e.g. >90%) and no (<10%) Am(IV) or (V) can be detected in the rim zone. The occurrence of americium dioxide is avoided by the redox buffering activity of the uranium dioxide matrix.

Degueldre, Claude; Cozzo, Cedric; Martin, Matthias; Grolimund, Daniel; Mieszczynski, Cyprian

2013-06-01

354

X-ray crystal structure and time-resolved spectroscopy of the blue carotenoid violerythrin.  

PubMed

Violerythrin, a blue-colored carotenoid, has been investigated by X-ray crystallography and steady-state and ultrafast time-resolved absorption spectroscopy. The X-ray crystal structure of violerythrin shows that the molecule is nearly planar with the terminal rings positioned in the s-trans conformation. The steady-state and time-resolved spectroscopic data of violerythrin do not differ significantly from those of other carbonyl carotenoids with long (N > 10) pi-electron conjugated chains. This indicates that while the four carbonyl groups in violerythrin are critical for generating the bathochromic shift that leads to the blue color of the molecule, no dramatic changes attributable to a charge-transfer state known to affect the excited-state properties of carotenoids with short polyene chains occur. This may be due to the symmetric distribution of the carbonyl groups, which would preclude such an effect. The structural requirements for a blue, neutral, carotenoid are a planar, symmetric, cross-conjugated chromophore, containing at least 30 pi-electrons, a central polyene chain with 9 or 10 conjugated carbon-carbon double bonds connected at each end by an s-trans or trans bond to two identical, cyclic end groups, each possessing a conjugated keto group further cross-conjugated to another keto group, or a double bond in a quinoid type structure. PMID:20545330

Polívka, Tomás; Frank, Harry A; Enriquez, Miriam M; Niedzwiedzki, Dariusz M; Liaaen-Jensen, Synnøve; Hemming, Joanna; Helliwell, John R; Helliwell, Madeleine

2010-07-01

355

X-ray emission spectroscopy of bulk liquid water in "no-man's land".  

PubMed

The structure of bulk liquid water was recently probed by x-ray scattering below the temperature limit of homogeneous nucleation (TH) of ?232 K [J. A. Sellberg et al., Nature 510, 381-384 (2014)]. Here, we utilize a similar approach to study the structure of bulk liquid water below TH using oxygen K-edge x-ray emission spectroscopy (XES). Based on previous XES experiments [T. Tokushima et al., Chem. Phys. Lett. 460, 387-400 (2008)] at higher temperatures, we expected the ratio of the 1b1' and 1b1? peaks associated with the lone-pair orbital in water to change strongly upon deep supercooling as the coordination of the hydrogen (H-) bonds becomes tetrahedral. In contrast, we observed only minor changes in the lone-pair spectral region, challenging an interpretation in terms of two interconverting species. A number of alternative hypotheses to explain the results are put forward and discussed. Although the spectra can be explained by various contributions from these hypotheses, we here emphasize the interpretation that the line shape of each component changes dramatically when approaching lower temperatures, where, in particular, the peak assigned to the proposed disordered component would become more symmetrical as vibrational interference becomes more important. PMID:25637993

Sellberg, Jonas A; McQueen, Trevor A; Laksmono, Hartawan; Schreck, Simon; Beye, Martin; DePonte, Daniel P; Kennedy, Brian; Nordlund, Dennis; Sierra, Raymond G; Schlesinger, Daniel; Tokushima, Takashi; Zhovtobriukh, Iurii; Eckert, Sebastian; Segtnan, Vegard H; Ogasawara, Hirohito; Kubicek, Katharina; Techert, Simone; Bergmann, Uwe; Dakovski, Georgi L; Schlotter, William F; Harada, Yoshihisa; Bogan, Michael J; Wernet, Philippe; Föhlisch, Alexander; Pettersson, Lars G M; Nilsson, Anders

2015-01-28

356

X-ray emission spectroscopy of bulk liquid water in "no-man's land"  

NASA Astrophysics Data System (ADS)

The structure of bulk liquid water was recently probed by x-ray scattering below the temperature limit of homogeneous nucleation (TH) of ˜232 K [J. A. Sellberg et al., Nature 510, 381-384 (2014)]. Here, we utilize a similar approach to study the structure of bulk liquid water below TH using oxygen K-edge x-ray emission spectroscopy (XES). Based on previous XES experiments [T. Tokushima et al., Chem. Phys. Lett. 460, 387-400 (2008)] at higher temperatures, we expected the ratio of the 1b1' and 1b1? peaks associated with the lone-pair orbital in water to change strongly upon deep supercooling as the coordination of the hydrogen (H-) bonds becomes tetrahedral. In contrast, we observed only minor changes in the lone-pair spectral region, challenging an interpretation in terms of two interconverting species. A number of alternative hypotheses to explain the results are put forward and discussed. Although the spectra can be explained by various contributions from these hypotheses, we here emphasize the interpretation that the line shape of each component changes dramatically when approaching lower temperatures, where, in particular, the peak assigned to the proposed disordered component would become more symmetrical as vibrational interference becomes more important.

Sellberg, Jonas A.; McQueen, Trevor A.; Laksmono, Hartawan; Schreck, Simon; Beye, Martin; DePonte, Daniel P.; Kennedy, Brian; Nordlund, Dennis; Sierra, Raymond G.; Schlesinger, Daniel; Tokushima, Takashi; Zhovtobriukh, Iurii; Eckert, Sebastian; Segtnan, Vegard H.; Ogasawara, Hirohito; Kubicek, Katharina; Techert, Simone; Bergmann, Uwe; Dakovski, Georgi L.; Schlotter, William F.; Harada, Yoshihisa; Bogan, Michael J.; Wernet, Philippe; Föhlisch, Alexander; Pettersson, Lars G. M.; Nilsson, Anders

2015-01-01

357

CuK? resonant x-ray emission spectroscopy of high- Tc -related cuprates  

NASA Astrophysics Data System (ADS)

The pre-edge structure of Cu1s excitations of high Tc cuprates reflects the lowest-lying unoccupied electronic states in these materials, and thus it is directly relevant to the interesting low-energy excitations and their nonlocal characters. We have performed theoretical calculations of the CuK? resonant x-ray emission spectroscopy (RXES) in the pre-edge region of La2CuO4 with a Cu5O16 cluster model in order to analyze recent experimental data. The Cu1s to on-site Cu3d excitation by the electric quadrupole transition and the Cu1s to off-site Cu3d excitation by the electric dipole transition are taken into account, confirming that the off-site transition is indeed visible but that it is split due to the effect of both the local and the nonlocal components of screening. The calculated results of RXES spectra, as well as of x-ray absorption spectra by partial fluorescence yield method, are in reasonable agreement with the experimental data. The influence of the low-energy tail of Cu4p states and the effects of doping electrons and holes are also calculated and discussed. Calculations are made for CuK? RXES of one-dimensional corner and edge sharing cuprates and compared to new experimental results for Sr2CuO3 and GeCuO3 .

Kotani, A.; Okada, K.; Vankó, György; Dhalenne, G.; Revcolevschi, A.; Giura, P.; Shukla, Abhay

2008-05-01

358

Millisecond Kinetics of Nanocrystal Cation Exchange UsingMicrofluidic X-ray Absorption Spectroscopy  

SciTech Connect

We describe the use of a flow-focusing microfluidic reactorto measure the kinetics of theCdSe-to-Ag2Se nanocrystal cation exchangereaction using micro-X-ray absorption spectroscopy (mu XAS). The smallmicroreactor dimensions facilitate the millisecond mixing of CdSenanocrystal and Ag+ reactant solutions, and the transposition of thereaction time onto spatial coordinates enables the in situ observation ofthe millisecond reaction with mu XAS. XAS spectra show the progression ofCdSe nanocrystals to Ag2Se over the course of 100 ms without the presenceof long-lived intermediates. These results, along with supporting stoppedflow absorption experiments, suggest that this nanocrystal cationexchange reaction is highly efficient and provide insight into how thereaction progresses in individual particles. This experiment illustratesthe value and potential of in situ microfluidic X-ray synchrotrontechniques for detailed studies of the millisecond structuraltransformations of nanoparticles and other solution-phase reactions inwhich diffusive mixing initiates changes in local bond structures oroxidation states.

Chan, Emory M.; Marcus, Matthew A.; Fakra, Sirine; Elnaggar,Mariam S.; Mathies, Richard A.; Alivisatos, A. Paul

2007-05-07

359

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

SciTech Connect

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

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

1995-08-01

360

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms.  

PubMed

X-ray photoelectron spectroscopy (XPS) is one of the best tools for studying the chemical modification of surfaces, and in particular the distribution and bonding of heteroatom dopants in carbon nanomaterials such as graphene and carbon nanotubes. Although these materials have superb intrinsic properties, these often need to be modified in a controlled way for specific applications. Towards this aim, the most studied dopants are neighbors to carbon in the periodic table, nitrogen and boron, with phosphorus starting to emerge as an interesting new alternative. Hundreds of studies have used XPS for analyzing the concentration and bonding of dopants in various materials. Although the majority of works has concentrated on nitrogen, important work is still ongoing to identify its precise atomic bonding configurations. In general, care should be taken in the preparation of a suitable sample, consideration of the intrinsic photoemission response of the material in question, and the appropriate spectral analysis. If this is not the case, incorrect conclusions can easily be drawn, especially in the assignment of measured binding energies into specific atomic configurations. Starting from the characteristics of pristine materials, this review provides a practical guide for interpreting X-ray photoelectron spectra of doped graphitic carbon nanomaterials, and a reference for their binding energies that are vital for compositional analysis via XPS. PMID:25671162

Susi, Toma; Pichler, Thomas; Ayala, Paola

2015-01-01

361

X-ray photoelectron spectroscopy of graphitic carbon nanomaterials doped with heteroatoms  

PubMed Central

Summary X-ray photoelectron spectroscopy (XPS) is one of the best tools for studying the chemical modification of surfaces, and in particular the distribution and bonding of heteroatom dopants in carbon nanomaterials such as graphene and carbon nanotubes. Although these materials have superb intrinsic properties, these often need to be modified in a controlled way for specific applications. Towards this aim, the most studied dopants are neighbors to carbon in the periodic table, nitrogen and boron, with phosphorus starting to emerge as an interesting new alternative. Hundreds of studies have used XPS for analyzing the concentration and bonding of dopants in various materials. Although the majority of works has concentrated on nitrogen, important work is still ongoing to identify its precise atomic bonding configurations. In general, care should be taken in the preparation of a suitable sample, consideration of the intrinsic photoemission response of the material in question, and the appropriate spectral analysis. If this is not the case, incorrect conclusions can easily be drawn, especially in the assignment of measured binding energies into specific atomic configurations. Starting from the characteristics of pristine materials, this review provides a practical guide for interpreting X-ray photoelectron spectra of doped graphitic carbon nanomaterials, and a reference for their binding energies that are vital for compositional analysis via XPS.

Pichler, Thomas; Ayala, Paola

2015-01-01

362

Local structure of Fe-doped films investigated by X-ray absorption fine structure spectroscopy  

NASA Astrophysics Data System (ADS)

films were deposited on Si (100) substrates by RF-magnetron sputtering technique. The influence of Fe doping on the local structure of films was investigated by X-ray absorption spectroscopy (XAS) at Fe K-edge and L-edge. For the films with , Fe ions dissolve into and substitute for sites with a mixed-valence state () of Fe ions. However, a secondary phase of Fe metal clusters is formed in the films with . The qualitative analyses of Fe-K edge extended X-ray absorption fine structure (EXAFS) reveal that the Fe-O bond length shortens and the corresponding Debye-Waller factor () increases with the increase of Fe concentration, indicating the relaxation of oxygen environment of Fe ions upon substitution. The anomalously large structural disorder and very short Fe-O distance are also observed in the films with high Fe concentration. Linear combination fittings at Fe L-edge further confirm the coexistence of and with a ratio of () for the film with . However, a significant fraction () of the Fe metal clusters is found in the film with.

An, Yukai; Wang, Shiqi; Feng, Deqiang; Wu, Zhonghua; Liu, Jiwen

2014-06-01

363

Mossbauer spectroscopy and X-ray diffraction of samples from the Santa Catharina iron meteorite  

NASA Technical Reports Server (NTRS)

Conversion electron Mossbauer spectroscopy (CEMS) of samples from the Santa Catharina iron meteorite shows the presence of the ordered iron-nickel phase with 50% Ni, tetrataenite, and of the paramagnetic iron-nickel phase with 25% Ni. The FeNi phase with 50% Ni amounts to 70% of the iron-nickel alloys. Futhermore, the CEM spectra show the presence of small peaks from one or more spinel compounds. These small peaks are more pronounced when regions near the rim of the samples are analyzed. The X-ray diffraction of different areas of the samples, both optically dark and optically light areas, shows the presence of a diffraction pattern from a single f.c.c. lattice with a lattice parameter of a=3.58A This means that the two different Fe-Ni phases seen in the CEMS analysis occupy the same lattice. The X-ray photographs also show the presence of super-structure reflections from the ordered FeNi phase, and that the orientation of the f.c.c. lattice is the same within the whole sample.

Roy-Poulsen, H.; Clarke, R. S., Jr.; Jensen, G. B.; Knudsen, J. M.; Larsen, L.; Roy-Poulsen, N. O.; Vistisen, L.

1984-01-01

364

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser.  

PubMed

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T; Thomas, Richard D; Larsson, Mats; Richter, Robert; Prince, Kevin C; Bozek, John D; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N; Tashiro, Motomichi; Ehara, Masahiro

2011-10-11

365

Optical Metrology for the Segmented Optics on the Constellation-X Spectroscopy X-Ray Telescope  

NASA Technical Reports Server (NTRS)

We present the metrology requirements and metrology implementation necessary to prove out the reflector technology for the Constellation X(C-X) spectroscopy X-ray telescope (SXT). This segmented, 1.6m diameter highly nested Wolter-1 telescope presents many metrology and alignment challenges. In particular, these mirrors have a stringent imaging error budget as compared to their intrinsic stiffness; This is required for Constellation-X to have sufficient effective area with the weight requirement. This has implications for the metrology that can be used. A variety of contract and noncontact optical profiling and interferometric methods are combined to test the formed glass substrates before replication and the replicated reflector segments.The reflectors are tested both stand-alone and in-situ in an alignment tower.Some of these methods have not been used on prior X-ray telescopes and some are feasible only because of the segmented approach used on the SXT. Methods discussed include high precision coordinate measurement machines using very low force or optical probe axial interferometric profiling azimuthal circularity profiling and use of advanced null optics such as conical computer generated hologram (CGHs).

Content, David; Colella, David; Fleetwood, Charles; Hadjimichael, Theo; Lehan, John; McMann, Joseph; Reid, Paul; Saha, Timo; Wright, Geraldine; Zhang, William

2004-01-01

366

Double-core-hole spectroscopy for chemical analysis with an intense X-ray femtosecond laser  

PubMed Central

Theory predicts that double-core-hole (DCH) spectroscopy can provide a new powerful means of differentiating between similar chemical systems with a sensitivity not hitherto possible. Although DCH ionization on a single site in molecules was recently measured with double- and single-photon absorption, double-core holes with single vacancies on two different sites, allowing unambiguous chemical analysis, have remained elusive. Here we report that direct observation of double-core holes with single vacancies on two different sites produced via sequential two-photon absorption, using short, intense X-ray pulses from the Linac Coherent Light Source free-electron laser and compare it with theoretical modeling. The observation of DCH states, which exhibit a unique signature, and agreement with theory proves the feasibility of the method. Our findings exploit the ultrashort pulse duration of the free-electron laser to eject two core electrons on a time scale comparable to that of Auger decay and demonstrate possible future X-ray control of physical inner-shell processes. PMID:21969540

Berrah, Nora; Fang, Li; Murphy, Brendan; Osipov, Timur; Ueda, Kiyoshi; Kukk, Edwin; Feifel, Raimund; van der Meulen, Peter; Salen, Peter; Schmidt, Henning T.; Thomas, Richard D.; Larsson, Mats; Richter, Robert; Prince, Kevin C.; Bozek, John D.; Bostedt, Christoph; Wada, Shin-ichi; Piancastelli, Maria N.; Tashiro, Motomichi; Ehara, Masahiro

2011-01-01

367

Determination of uranyl incorporation into biogenic manganese oxides using X-ray absorption spectroscopy and scattering  

USGS Publications Warehouse

Biogenic manganese oxides are common and an important source of reactive mineral surfaces in the environment that may be potentially enhanced in bioremediation cases to improve natural attenuation. Experiments were performed in which the uranyl ion, UO22+ (U(VI)), at various concentrations was present during manganese oxide biogenesis. At all concentrations, there was strong uptake of U onto the oxides. Synchrotron-based extended X-ray absorption fine structure (EXAFS) spectroscopy and X-ray diffraction (XRD) studies were carried out to determine the molecular-scale mechanism by which uranyl is incorporated into the oxide and how this incorporation affects the resulting manganese oxide structure and mineralogy. The EXAFS experiments show that at low concentrations (2 mol % U, >4 ??M U(VI) in solution), the presence of U(VI) affects the stability and structure of the Mn oxide to form poorly ordered Mn oxide tunnel structures, similar to todorokite. EXAFS modeling shows that uranyl is present in these oxides predominantly in the tunnels of the Mn oxide structure in a tridentate complex. Observations by XRD corroborate these results. Structural incorporation may lead to more stable U(VI) sequestration that may be suitable for remediation uses. These observations, combined with the very high uptake capacity of the Mn oxides, imply that Mn-oxidizing bacteria may significantly influence dissolved U(VI) concentrations in impacted waters via sorption and incorporation into Mn oxide biominerals. ?? 2006 American Chemical Society.

Webb, S.M.; Fuller, C.C.; Tebo, B.M.; Bargar, J.R.

2006-01-01

368

Probing hot-electron effects in wide area plasmonic surfaces using X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Plasmon enhanced hot carrier formation in metallic nanostructures increasingly attracts attention due to potential applications in photodetection, photocatalysis, and solar energy conversion. Here, hot-electron effects in nanoscale metal-insulator-metal (MIM) structures are investigated using a non-contact X-ray photoelectron spectroscopy based technique using continuous wave X-ray and laser excitations. The effects are observed through shifts of the binding energy of the top metal layer upon excitation with lasers of 445, 532, and 650 nm wavelength. The shifts are polarization dependent for plasmonic MIM grating structures fabricated by electron beam lithography. Wide area plasmonic MIM surfaces fabricated using a lithography free route by the dewetting of evaporated Ag on HfO2 exhibit polarization independent optical absorption and surface photovoltage. Using a simple model and making several assumptions about the magnitude of the photoemission current, the responsivity and external quantum efficiency of wide area plasmonic MIM surfaces are estimated as 500 nA/W and 11 × 10-6 for 445 nm illumination.

Ayas, Sencer; Cupallari, Andi; Dana, Aykutlu

2014-12-01

369

The Chemistry os Spent Nuclear Fuel From X-Ray Absorption Spectroscopy  

SciTech Connect

Present and future nuclear fuel cycles will require an understanding of the complex chemistry of trace fission products and transuranium actinides in spent nuclear fuel (SNF). Because of the unique analytical challenges presented by SNF to the materials scientist, many of its fundamental physical and chemical properties remain poorly understood, especially on the microscopic scale. Such an understanding of the chemical states of radionuclides in SNF would benefit development of technologies for fuel monitoring, fuel performance improvement and modeling, fuel reprocessing, and spent fuel storage and disposal. We have recently demonstrated the use of synchrotron x-ray absorption spectroscopy (XAS) to examine crystal chemical properties of actinides and fission products in extracted specimens of SNF. Information obtained includes oxidation state, chemical bond coordination, and quantitative elemental concentration and distribution. We have also used XAS in a scanning mode to obtain x-ray spectral micrographs with resolution approaching 1 micron. A brief overview of the technique will be presented, along with findings on uranium, plutonium, neptunium, technetium, and molybdenum in commercial PWR SNF specimens.

F.A. Fortner; A.J. Kropf; J.C. Cunnane

2006-09-21

370

The ultra-deep XMM survey in the CDFS: X-ray spectroscopy of heavily obscured AGN.  

NASA Astrophysics Data System (ADS)

We present selected results on the X-ray spectroscopy of distant, obscured AGN as obtained with the ultra-deep (? 3 Ms) XMM-Newton survey in the Chandra Deep Field South (CDF-S). One of the primary goals of the project is to characterize the X-ray spectral properties of heavily obscured and Compton-thick AGN over the range of redshifts and luminosities that are relevant in terms of their contribution to the X-ray background. The ultra-deep exposure, coupled with the XMM detector's spectral throughput, allowed us to accumulate X-ray spectra for more than 100 AGN and to investigate the absorption distribution up to z˜4.

Comastri, Andrea; XMM-CDFS Team

371

Soft X-ray absorption spectroscopy and resonant inelastic X-ray scattering spectroscopy below 100 eV: probing first-row transition-metal M-edges in chemical complexes.  

PubMed

X-ray absorption and scattering spectroscopies involving the 3d transition-metal K- and L-edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M-edges, which are below 100 eV. Synchrotron-based X-ray sources can have higher energy resolution at M-edges. M-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) could therefore provide complementary information to K- and L-edge spectroscopies. In this study, M2,3-edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M2,3-edge RIXS on NiO, NiF2 and two other covalent complexes have been performed and different d-d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M-edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high-sensitivity and high-resolution superconducting tunnel junction X-ray detectors below 100 eV is also illustrated and discussed. PMID:23765304

Wang, Hongxin; Young, Anthony T; Guo, Jinghua; Cramer, Stephen P; Friedrich, Stephan; Braun, Artur; Gu, Weiwei

2013-07-01

372

A Fully Bayesian Method for Jointly Fitting Instrumental Calibration and X-Ray Spectral Models  

NASA Astrophysics Data System (ADS)

Owing to a lack of robust principled methods, systematic instrumental uncertainties have generally been ignored in astrophysical data analysis despite wide recognition of the importance of including them. Ignoring calibration uncertainty can cause bias in the estimation of source model parameters and can lead to underestimation of the variance of these estimates. We previously introduced a pragmatic Bayesian method to address this problem. The method is "pragmatic" in that it introduced an ad hoc technique that simplified computation by neglecting the potential information in the data for narrowing the uncertainty for the calibration product. Following that work, we use a principal component analysis to efficiently represent the uncertainty of the effective area of an X-ray (or ?-ray) telescope. Here, however, we leverage this representation to enable a principled, fully Bayesian method that coherently accounts for the calibration uncertainty in high-energy spectral analysis. In this setting, the method is compared with standard analysis techniques and the pragmatic Bayesian method. The advantage of the fully Bayesian method is that it allows the data to provide information not only for estimation of the source parameters but also for the calibration product—here the effective area, conditional on the adopted spectral model. In this way, it can yield more accurate and efficient estimates of the source parameters along with valid estimates of their uncertainty. Provided that the source spectrum can be accurately described by a parameterized model, this method allows rigorous inference about the effective area by quantifying which possible curves are most consistent with the data.

Xu, Jin; van Dyk, David A.; Kashyap, Vinay L.; Siemiginowska, Aneta; Connors, Alanna; Drake, Jeremy; Meng, Xiao-Li; Ratzlaff, Pete; Yu, Yaming

2014-10-01

373

Effect of Intermolecular Interactions on the Carbon 1s Near Edge X-ray Absorption Fine Structure (NEXAFS) Spectroscopy of n-Alkanes.  

E-print Network

??“Matrix effects” in Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy are the spectroscopic changes induced by intermolecular interactions, providing sensitivity to local structure and… (more)

Neelakanni mudiyanselage, Sahan

2014-01-01

374

A study of the elemental composition of diabases by instrumental neutron activation and X-ray fluorescence analysis  

Microsoft Academic Search

The distribution of the elemental composition was studied mainly for microelements in the diabases of the Pechenga suite subjected\\u000a to various changes. Investigations were conducted by a combination of instrumental neutron activation INAA and X-ray fluoresence\\u000a XRFA analyses. The INAA was conducted with sample weights of 20–100 mg exposed to irradiation in a nuclear reactor by a flux\\u000a of neutrons

A. V. Gurevich; Z. V. Vikhrova; V. Ya Vyropayev; V. I. Drynkin; D. I. Leipunskaya; I. Ya. Shirokova

1980-01-01

375

Development of Kilo-Pixel Arrays of Transition-Edge Sensors for X-Ray Spectroscopy  

NASA Technical Reports Server (NTRS)

We are developing kilo-pixel arrays of transition-edge sensor (TES) microcalorimeters for future X-ray astronomy observatories or for use in laboratory astrophysics applications. For example, Athena/XMS (currently under study by the european space agency) would require a close-packed 32x32 pixel array on a 250-micron pitch with < 3.0 eV full-width-half-maximum energy resolution at 6 keV and at count-rates of up to 50 counts/pixel/second. We present characterization of 32x32 arrays. These detectors will be readout using state of the art SQUID based time-domain multiplexing (TDM). We will also present the latest results in integrating these detectors and the TDM readout technology into a 16 row x N column field-able instrument.

Adams, J. S.; Bandler, S. R.; Busch, S. E.; Chervenak, J. A.; Chiao, M. P.; Eckart, M. E.; Ewin, A. J.; Finkbeiner, F. M.; Kelley, R. L.; Kelly, D. P.; Kilbourne, C. A.; Leutenegger, M. A.; Porst, J.-P.; Porter, F. S.; Ray, C. A.; Sadleir, J. E.; Smith, S. J.; Wassell, E. J.; Doriese, W. B.; Fowler, J. W.; Hilton, G. C.; Irwin, K. D.; Reintsema, C. D.; Smith, D. R.; Swetz, D. S.

2012-01-01

376

X-ray photoelectron spectroscopy study of excimer laser treated alumina films  

NASA Astrophysics Data System (ADS)

Amorphous alumina layers are deposited on a single crystal Si substrate by a e-gun evaporation technique. These films are then thermally annealed in oxygen to be crystallized and, further, irradiated with an excimer laser beam. At each stage of the film preparation, an x-ray photoelectron spectroscopy analysis is performed at the film surface and in depth, upon ion beam grinding. Results give evidence for the formation of an aluminosilicate upon thermal annealing of the film in oxygen. At the surface itself, this compound is observed to decompose upon excimer laser irradiation at energy densities exceeding 1.75 J/cm2, giving rise to free Si atoms and SiO2, however with complete disappearance of Al atoms. Model photochemical reactions are proposed to explain such transformations.

Georgiev, D. G.; Kolev, K.; Laude, L. D.; Mednikarov, B.; Starbov, N.

1998-01-01

377

X-Ray Absorption Spectroscopy Of Thin Foils Irradiated By An Ultra-short Laser Pulse  

NASA Astrophysics Data System (ADS)

Point-projection K-shell absorption spectroscopy has been used to measure absorption spectra of transient plasma created by an ultra-short laser pulse. The 1s-2p and 1s-3p absorption lines of weakly ionized aluminum and the 2p-3d absorption lines of bromine were measured over an extended range of densities in a low-temperature regime. Independent plasma characterization was obtained using frequency domain interferometry diagnostic (FDI) that allows the interpretation of the absorption spectra in terms of spectral opacities. Assuming local thermodynamic equilibrium, spectral opacity calculations have been performed using the density and temperature inferred from the FDI diagnostic to compare to the measured absorption spectra. A good agreement is obtained when non-equilibrium effects due to non-stationary atomic physics are negligible at the x-ray probe time.

Renaudin, P.; Lecherbourg, L.; Blancard, C.; Cossé, P.; Faussurier, G.; Audebert, P.; Bastiani-Ceccotti, S.; Geindre, J.-P.; Shepherd, R.

2007-08-01

378

The transfer of polytetrafluoroethylene studied by X-ray photoelectron spectroscopy  

NASA Technical Reports Server (NTRS)

A polytetrafluoroethylene (PTFE) sphere of radius 4.8 mm was rubbed against nickel and S-Monel at speeds from 0.94 to 94 mm/s and at loads from 0.19 to 3.9 N. The transfer film of PTFE on the metal was examined with X-ray photoelectron spectroscopy. In all cases the film was found to be indistinguishable from bulk PTFE. A trace of metal fluoride was observed whether the rubbing took place on oxidized or atomically clean metal. The film was of the order of a molecule thick for the entire range of loads and did not increase with repeated passes over the same rubbed area. An erratic increase in thickness at rubbing speeds above 10 mm/s was taken as evidence of random transfer of bulk material.

Wheeler, D. R.

1981-01-01

379

Surface properties of SmB6 from x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

We have investigated the properties of cleaved SmB6 single crystals by x-ray photoelectron spectroscopy. At low temperatures and freshly cleaved samples a surface core level shift is observed which vanishes when the temperature is increased. A Sm valence between 2.5 and 2.6 is derived from the relative intensities of the Sm2 + and Sm3 + multiplets. The B/Sm intensity ratio obtained from the core levels is always larger than the stoichiometric value. Possible reasons for this deviation are discussed. The B 1s signal shows an unexpected complexity: An anomalous low energy component appears with increasing temperature and is assigned to the formation of a suboxide at the surface. While several interesting intrinsic and extrinsic properties of the SmB6 surface are elucidated in this manuscript, no clear indication of a trivial mechanism for the prominent surface conductivity is found.

Heming, N.; Treske, U.; Knupfer, M.; Büchner, B.; Inosov, D. S.; Shitsevalova, N. Y.; Filipov, V. B.; Krause, S.; Koitzsch, A.

2014-11-01

380

Insufficiency of O and Cu holes for oxide superconductivity: X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

We have studied the electronic properties of YBa2Cu3O7 and EuBa2Cu3O7 superconductors with soft x-ray absorption spectroscopy (XAS) at BESSY. Electronic transitions to unoccupied states (holes) of 2p and 3d character on O and Cu, respectively, are found in superconducting specimens. In samples with reduced oxygen content, superconductivity is suppressed, and a decrease in the intensity of transitions to these unoccupied states is observed. However, there is little change in these features when Zn sufficient to suppress supercondicutivity is substituted for Cu. We conclude that O 2p and Cu 3d holes are necessary but not sufficient for superconductivity.

Denboer, M. L.; Chang, C. L.; Petersen, H.; Schaible, M.; Reilly, K.; Horn, S.

1988-10-01

381

X-ray Diffraction and Raman Spectroscopy Study of a Pressure Induced Transition in [123]tetramantane  

NASA Astrophysics Data System (ADS)

Diamondoids, nanometer-sized hydrocarbons consisting of fused diamond-like cages, exhibit many interesting electronic, optical, mechanical and thermal properties. They were initially found in petroleum in small quantities as a molecular proxy for thermal maturity of source rocks and crude oils. We combined high pressure x-ray diffraction (XRD) and Raman spectroscopy to investigate the behavior of [123]tetramantane, a higher diamondoid made up of four carbon cages to 20 GPa. A phase transition was observed at approximately 11GPa from P1 space group to a new high pressure phase. This transition was found to be reversible with a large pressure hysteresis. Raman studies confirmed changes in bonding in [123]tetramantane based on the dln?/dP of peak shifting with pressure and changes in the relative intensity of the most intense peaks. Our study may have implications for developing an alternative approach to synthesis of higher diamondoids.

Hou, Y.; Lin, Y.; Mao, W. L.

2011-12-01

382

The hydration structure of aqueous carbonic acid from X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

Despite much effort, aqueous carbonic acid (H2CO3) remains poorly characterized because it is very short-lived. We describe the detection and characterization of aqueous H2CO3 by X-ray absorption spectroscopy, wherein protonation of a bicarbonate solution continuously generates the acid under ambient conditions. Accompanying first principles calculations of the carbon K-edge transitions facilitate spectral assignment and interpretation in terms of the H2CO3 ?* orbital, which exhibits a small (0.2 eV), systematic blueshift relative to that of bicarbonate. These results establish the detailed hydration properties of this short-lived molecule and will thereby facilitate future studies of carbonate chemistry in biological and geological system.

Lam, Royce K.; England, Alice H.; Sheardy, Alex T.; Shih, Orion; Smith, Jacob W.; Rizzuto, Anthony M.; Prendergast, David; Saykally, Richard J.

2014-10-01

383

Band alignment at memristive metal-oxide interfaces investigated by hard x-ray photoemission spectroscopy  

NASA Astrophysics Data System (ADS)

The electronic structure and band alignment at metal/oxide interfaces for nonvolatile memory applications are investigated by hard x-ray photoelectron spectroscopy (HAXPES) and DC transport measurements, using acceptor doped SrTiO3 as a model memristive oxide. Metal-insulator-metal (MIM) structures with a noble metal (Pt) top electrode form a Schottky barrier and exhibit rectifying properties, while a reactive metal (Ti) as top electrode shows symmetric I(V) characteristics and a flat band situation at the interface. The transition from rectifying to ohmic I(V) relations with increasing Ti thickness is discussed with respect to the electrochemical reaction at the interface, the band alignment at the electrode/oxide interface, and the slope of the energy bands across the MIM structure.

Lenser, C.; Köhl, A.; Patt, M.; Schneider, C. M.; Waser, R.; Dittmann, R.

2014-09-01

384

Atomic-scale chemical quantification of oxide interfaces using energy-dispersive X-ray spectroscopy  

SciTech Connect

Atomic-scale quantification of chemical composition across oxide interfaces is important for understanding physical properties of epitaxial oxide nanostructures. Energy-dispersive X-ray spectroscopy (EDS) in an aberration-corrected scanning transmission electron microscope was used to quantify chemical composition across the interface of ferromagnetic La{sub 0.7}Sr{sub 0.3}MnO{sub 3} and antiferromagnetic BiFeO{sub 3} quantum structure. This research demonstrates that chemical composition at atomic columns can be quantified by Gaussian peak-fitting of EDS compositional profiles across the interface. Cation diffusion was observed at both A- and B-sublattice sites; and asymmetric chemical profiles exist across the interface, consistent with the previous studies.

Lu, Ping; Van Benthem, Mark [Sandia National Laboratories, P.O. Box 5800, MS 1411, Albuquerque, New Mexico 87185-1411 (United States)] [Sandia National Laboratories, P.O. Box 5800, MS 1411, Albuquerque, New Mexico 87185-1411 (United States); Xiong, Jie; Jia, Quanxi [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)

2013-04-29

385

Relaxation of Cs atomic polarization at surface coatings characterized by X-ray photoelectron spectroscopy  

E-print Network

Paraffin coatings on glass slides were investigated through both X-ray photoelectron spectroscopy (XPS) and spin relaxation measurement for cesium (Cs) vapor. The components of the glass substrate, such as silicon (Si) and oxygen (O), existed in the XPS spectra of the coated slides, indicating the imperfection of the prepared paraffin coatings. The substrate was not observed after the annealing of the coatings in Cs vapor, which is known as a `ripening' process for spin relaxation measurement. We found a general trend that effective anti-spin relaxation performance requires high paraffin and low Cs coverage on the surface. We also examined a type of diamond-like carbon (DLC) film, anticipating the effect of anti-spin relaxation; our attempts have failed to date.

Kushida, K; Moriya, T; Shimizu, T; Meguro, K; Nakazawa, H; Hatakeyama, A

2014-01-01

386

An early explanation of the periodic table: Lars Vegard and X-ray spectroscopy  

E-print Network

The Norwegian physicist Lars Vegard may have been the first to propose electron configurations for all the chemical elements, from hydrogen to uranium, on the basis of quantum atomic theory. This he did in papers of 1918-1919 in which he argued that the principal quantum number corresponded to the shells in Bohr's picture of atomic structure. Vegard's theory of the periodic system, based on the methods of theoretical X-ray spectroscopy in particular, was a significant advance but exerted little influence on the further development. It presupposed atoms made up of planar electron rings, and with the abandonment of the ring atom about 1920 this and similar models lost their credibility.

Kragh, Helge

2011-01-01

387

Fast X-ray Photon Correlation Spectroscopy measurements from the diffusion of concentrated Alpha Crystallin suspensions  

NASA Astrophysics Data System (ADS)

Alpha Crystallin constitute up to half of the total protein found in the mammalian eye lens. It has chaperone like behavior and may play a key role in maintaining lens transparency by preventing condensation of other lens proteins. We report here Fast X-ray Photon Correlation Spectroscopy (XPCS) measurements of protein diffusion within concentrated suspensions of Alpha Crystallin. Bovine calf eye lens cortices were homogenized, centrifuged and ultra-filtered to obtain concentrated Alpha Crystallin suspensions. Diffusion of proteins within these suspensions was measured as a function of temperature. The overall observed diffusion rates imply that the proteins exist in a glassy or gel phase, even at concentrations where equivalent hard sphere system would still be liquid. We interpret these results within the context of strongly interacting proteins, with protein-protein interactions possibly mediated by subunit exchange among Alpha Crystallin oligormers.

Nuwan Karunaratne, Vidanage; Debartolo, Janae; Berry, Justin; Lurio, Laurence; Thurston, George; Narayanan, Suresh; Sandy, Alec; Weizeorick, John

2011-03-01

388

The irradiation of ammonia ice studied by near edge x-ray absorption spectroscopy  

SciTech Connect

A vapor-deposited NH{sub 3} ice film irradiated at 20 K with 150 eV photons has been studied with near-edge x-ray absorption fine structure (NEXAFS) spectroscopy at the nitrogen K-edge. Irradiation leads to the formation of high amounts (12%) of molecular nitrogen N{sub 2}, whose concentration as a function of the absorbed energy has been quantified to 0.13 molecule/eV. The stability of N{sub 2} in solid NH{sub 3} has been also studied, showing that N{sub 2} continuously desorbs between 20 and 95 K from the irradiated ammonia ice film. Weak concentrations (<1%) of other photoproducts are also detected. Our NEXAFS simulations show that these features own to NH{sub 2}, N{sub 2}H{sub 2}, and N{sub 3}{sup -}.

Parent, Ph.; Bournel, F.; Lasne, J.; Laffon, C.; Carniato, S. [Laboratoire de Chimie Physique, CNRS, UMR 7614, Matiere et Rayonnement, 11 rue Pierre et Marie Curie, 75231 Paris Cedex 05 (France); Lacombe, S. [Laboratoire des Collisions Atomiques et Moleculaires (LCAM), CNRS, 91405 Orsay Cedex, France and Universite Paris Sud 11, Bat 351, 91405 Orsay Cedex (France); Strazzulla, G. [INAF-Ossevatorio Astrofisico, Via S. Sofia 78, 95123 Catania (Italy); Gardonio, S.; Lizzit, S. [Sincrotrone Trieste S.C.p.A., S. S. 14 Km 163.5, Basovizza, 34012 Trieste (Italy); Kappler, J.-P. [Institut de Physique et Chimie des Materiaux de Strasbourg, UMR 7504, ULP-CNRS, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Joly, L. [Institut de Physique et Chimie des Materiaux de Strasbourg, UMR 7504, ULP-CNRS, 23 rue du Loess, BP 43, F-67034 Strasbourg Cedex 2 (France); Swiss Light Source, Paul Scherrer Institut, Villigen PSI, 5232 Villigen (Switzerland)

2009-10-21

389

Photosynthetic Dioxygen Formation Monitored by Time-Resolved X-Ray Spectroscopy  

SciTech Connect

Photosynthetic water oxidation provides the dioxygen of the atmosphere. Its partial reactions proceed at a Mn4Ca complex bound to photosystem II of plants and cyanobacteria. Understanding the mechanism of this biological oxidation of water molecules to O2 is one of the major challenges in life sciences. We have developed and employed X-ray absorption Spectroscopy (XAS) techniques facilitating measurements on metalloenzymes at room temperature. By these techniques, we were able to resolve structural changes at the Mn ions, to follow oxidation-state changes in the microseconds time domain, and to detect a novel and likely crucial intermediate in the oxygen-evolving step of the catalytic cycle of the Mn complex. Based on the obtained results, we replace the classic S-state model of the catalytic cycle by a more elaborated reaction scheme which solves apparent inconsistencies of earlier models, explains a large body of experimental results, and provides a fresh twist in photosynthesis research.

Haumann, Michael; Dau, Holger [Freie Universitaet Berlin, Inst. f. Experimentalphysik, Arnimallee 14, D-14195 Berlin (Germany)

2007-02-02

390

In situ X-ray Raman spectroscopy of LiBH4.  

PubMed

X-Ray Raman Spectroscopy (XRS) is used to study the electronic properties of bulk lithium borohydride (LiBH(4)) and LiBH(4) in porous carbon nano-composites (LiBH(4)/C) during dehydrogenation. The lithium (Li), boron (B) and carbon (C) K-edges are studied and compared with calculations of the starting material and intermediate compounds. Comparison of the B and C K-edge XRS spectra of the as-prepared samples with rehydrogenated samples shows that the B and C electronic structure is largely regained after rehydrogenation. Both Li and C K-edge spectra show that during dehydrogenation, part of the Li intercalates into the porous carbon. This study shows that XRS in combination with calculations is a promising tool to study the electronic properties of nano-crystalline light-weight materials for energy storage. PMID:22428166

Miedema, Piter S; Ngene, Peter; van der Eerden, Ad M J; Weng, Tsu-Chien; Nordlund, Dennis; Sokaras, Dimosthenis; Alonso-Mori, Roberto; Juhin, Amélie; de Jongh, Petra E; de Groot, Frank M F

2012-04-28

391

Near-edge X-ray absorption fine structure spectroscopy of MDI and TDI polyurethane polymers  

SciTech Connect

The sensitivity of near-edge X-ray absorption fine structure (NEXAFS) to differences in key chemical components of polyurethane polymers is presented. Carbon is NEXAFS spectra of polyurethane polymers made from 4,4{prime}-methylene di-p-phenylene isocyanate (MDI) and toluene diisocyanate (TDI) isocyanate monomers illustrate that there is an unambiguous spectroscopic fingerprint for distinguishing between MDI-based and TDI-based polyurethane polymers. NEXAFS spectra of MDI and TDI polyurea and polyurethane models show that the urea and carbamate (urethane) linkages in these polymers can be distinguished. The NEXAFS spectroscopy of the polyether component of these polymers is discussed, and the differences between the spectra of MDI and TDI polyurethanes synthesized with polyether polyols of different molecular composition and different molecular weight are presented. These polymer spectra reported herein provide appropriate model spectra to represent the pure components for quantitative microanalysis.

Urquhart, S.G.; Smith, A.P.; Ade, H.W. [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics] [North Carolina State Univ., Raleigh, NC (United States). Dept. of Physics; Hitchcock, A.P. [McMaster Univ., Hamilton, Ontario (Canada). Brockhouse Inst. for Materials Research] [McMaster Univ., Hamilton, Ontario (Canada). Brockhouse Inst. for Materials Research; Rightor, E.G. [Dow Chemical USA, Midland, MI (United States)] [Dow Chemical USA, Midland, MI (United States); Lidy, W. [Dow Chemical USA, Freeport, TX (United States)] [Dow Chemical USA, Freeport, TX (United States)

1999-06-03

392

X-ray emission spectroscopy and density functional study of CO/Fe(100)  

SciTech Connect

We report x-ray emission and absorption spectroscopy studies of the electronic structure of the predissociative {alpha}{sub 3} phase of CO bound at hollow sites of Fe(100) as well as of the on-top bound species in the high-coverage {alpha}{sub 1} phase. The analysis is supported by density functional calculations of structures and spectra. The bonding of ''lying down'' CO in the hollow site is well described in terms of {pi} to {pi}* charge transfer made possible through bonding interaction also at the oxygen in the minority spin-channel. The on-top CO in the mixed, high-coverage {alpha}{sub 1} phase is found to be tilted due to adsorbate-adsorbate interaction, but still with bonding mainly characteristic of ''vertical'' on-top adsorbed CO similar to other transition-metal surfaces.

Gladh, J.; Oeberg, H.; Li, Jibiao; Ljungberg, M. P.; Matsuda, A.; Pettersson, L. G. M.; Oestroem, H. [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Ogasawara, H. [Stanford Synchrotron Radiation Lightsource, P.O. Box 20450, Stanford, California 94309 (United States); Nilsson, A. [Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm (Sweden); Stanford Synchrotron Radiation Lightsource, P.O. Box 20450, Stanford, California 94309 (United States)

2012-01-21

393

Compositional analysis of Ceramic Glaze by Laser Induced Breakdown Spectroscopy and Energy Dispersive X-Ray  

NASA Astrophysics Data System (ADS)

Laser induced breakdown spectroscopy (LIBS) has been applied for the analysis of Egyptian Islamic glaze ceramic sample. The sample dating back to Fatimid period (969-1169AD), and collected from Al-Fustat excavation store in Cairo. The analysis of contaminated pottery sample has been performed to draw mapping for the elemental compositions by LIBS technique. LIBS measurements have been done by the fundamental wavelength (1064 nm) of Nd: YAG laser for the elemental analysis and performing the cleaning processes of the pottery sample. In addition, complementary analyses were carried out by scanning electron microscopy linked with energy dispersive X-ray microanalysis (SEM/EDX) to obtain verification of chemical results. The morphological surfaces before and after cleaning has been done by Optical Microscopy (OM).

Khedr, A.; Abdel-kareem, O.; Elnabi, S. H.; Harith, M. A.

2011-09-01

394

Uranium and thorium sorption on minerals studied by x-ray absorption spectroscopy  

SciTech Connect

Several actinide-mineral sorption systems were studied by uranium and thorium L{sub 3}-edge x-ray absorption spectroscopy. A series of layer silicate minerals, including micas, were selected for their systematic variations in surface structure, e.g. degree of permanent negative charge on the basal planes. An expansible layer silicate, vermiculite, was treated to provide several different interlayer spacings, allowing variations in the accessibility of interior cation exchange sites. The finely powdered minerals were exposed to aqueous solutions of uranyl chloride or thorium chloride. Analysis of the EXAFS and XANES spectra indicates the influence of the mineral substrate upon the local structure of the bound actinide species. Trends in the data are interpreted based upon the known variations in mineral structure.

Hudson, E.A.; Terminello, L.J.; Viani, B.E. [Lawrence Livremore National Lab., CA (United States)] [and others

1995-12-01

395

X-ray Absorption Spectroscopy Beamline at the Siam Photon Laboratory  

SciTech Connect

A bending magnet beamline has been constructed and commissioned for x-ray absorption spectroscopy (XAS) at the Siam Photon Laboratory. The photon energy is tunable from 1830 eV to 8000 eV using a Lemmonier-type, fixed-exit double crystal monochromator equipped with InSb(111), Si(111), Ge(220) crystals. Elemental K-edges are then accessible from silicon to iron. A series of low conductance vacuum tubes has been designed and installed between the pumping chambers in the front end to obtain the proper pressure difference between the upstream and the downstream of the front end. Thus lower-energy photons, around K-edges of silicon, phosphorous, and sulfur, can be delivered to the experimental XAS station without being absorbed by a window. In this report, the design of the beamline is described. The commissioning results including the measured photon flux at sample and experimental XAS spectra are presented.

Klysubun, Wantana; Tarawarakarn, Pongjakr; Sombunchoo, Panidtha; Klinkhieo, Supat; Chaiprapa, Jitrin [National Synchrotron Research Center, 111 University Ave., Muang District, Nakhon Ratchasima 30000 (Thailand); Songsiriritthigul, Prayoon [National Synchrotron Research Center, 111 University Ave., Muang District, Nakhon Ratchasima 30000 (Thailand); School of Physics, Suranaree University of Technology, Nakhon Ratchasima 30000 (Thailand)

2007-01-19

396

Visualizing interfacial charge transfer in dye sensitized nanoparticles using x-ray transient absorption spectroscopy.  

SciTech Connect

A molecular level understanding of the structural reorganization accompanying interfacial electron transfer is important for rational design of solar cells. Here we have applied XTA (X-ray transient absorption) spectroscopy to study transient structures in a heterogeneous interfacial system mimicking the charge separation process in dye-sensitized solar cell (DSSC) with Ru(dcbpy){sub 2}(NCS){sub 2} (RuN3) dye adsorbed to TiO{sub 2} nanoparticle surfaces. The results show that the average Ru-NCS bond length reduces by 0.06 {angstrom}, whereas the average Ru-N(dcbpy) bond length remains nearly unchanged after the electron injection. The differences in bond-order change and steric hindrance between two types of ligands are attributed to their structural response in the charge separation. This study extends the application of XTA into optically opaque hybrid interfacial systems relevant to the solar energy conversion.

Zhang, X. Y.; Smolentsev, G.; Guo, J.; Attenkofer, K.; Kurtz, C.; Jennings, G.; Lockard, J. V.; Stickrath, A. B.; Chen, L. X. (X-Ray Science Division); (Southern Federal Univ.); (Lund Univ.); (Northwestern Univ.)

2011-01-01

397

Comparative study of bandwidths in copper delafossites from x-ray emission spectroscopy  

NASA Astrophysics Data System (ADS)

The widths of the valence bands in the copper (I) delafossites CuGaO2 , CuInO2 , and CuScO2 have been measured by OK -shell x-ray emission spectroscopy and are compared with previous experimental work on CuAlO2 and CuCrO2 . In agreement with recent density-functional theory calculations it is found that the bandwidth decreases in the series CuAlO2>CuGaO2>CuInO2>CuScO2 . It is shown that states at the top of the valence band are of dominant Cu3dz2 atomic character but with significant mixing with O2p states.

Shin, D.; Foord, J. S.; Payne, D. J.; Arnold, T.; Aston, D. J.; Egdell, R. G.; Godinho, K. G.; Scanlon, D. O.; Morgan, B. J.; Watson, G. W.; Mugnier, E.; Yaicle, C.; Rougier, A.; Colakerol, L.; Glans, P. A.; Piper, L. F. J.; Smith, K. E.

2009-12-01

398

Characterization of interfacially electronic structures of gold-magnetite heterostructures using X-ray absorption spectroscopy.  

PubMed

Gold-magnetite heterostructures are novel nanomaterials which can rapidly catalyze the reduction reaction of nitroaromatics. In this study, the interfacially structural and electronic properties of various morphologies of Au-Fe3O4 heterostructures were systematically investigated using X-ray absorbance spectroscopy (XAS) and X-ray photoelectron spectroscopy (XPS). The effect of change in electronic structure and charge transfer on electrochemically catalytic activity of Au-Fe3O4 heterostructures was further evaluated by oxygen reduction reaction (ORR). The shifts in binding energy of Au4f and Fe2p peaks in XPS spectra indicate the charge transfer between the Au and Fe3O4 nanoparticles. The increase in d-hole population of Au seeds after the conjugation with iron oxides follows the order flower-like Au-Fe3O4 (FLNPs)>dumbbell-like Au-Fe3O4 (DBNPs)>Au seeds. In addition, the Fe(2+) valence state increases in Au-Fe3O4 heterostructures, which provides evidence to support the hypothesis of charge transfer between Au and Fe3O4 nanoparticles. The theoretical simulation of Au L3-edge XAS further confirms the production of Au-Fe and Au-O bonds at the interface of Au/Fe3O4 and the epitaxial linkage relationship between Au and Fe3O4 nanoparticles. In addition, the electron deficient of Au seeds increases upon increasing Fe3O4 nanoparticles on a single Au seed, and subsequently decreases the catalytic activity of Au in the Au-Fe3O4 heterostructures. The catalytic activity of Au-Fe3O4 toward ORR follows the order Au seeds>Au-Fe3O4 DBNPs>Au-Fe3O4 FLNPs, which is positively correlated to the extent of electronic deficiency of Au in Au-Fe3O4 heterostructures. PMID:24407694

Lin, Fang-hsin; Doong, Ruey-an

2014-03-01

399

X-ray optics metrology limited by random noise, instrumental drifts, and systematic errors  

SciTech Connect

Continuous, large-scale efforts to improve and develop third- and forth-generation synchrotron radiation light sources for unprecedented high-brightness, low emittance, and coherent x-ray beams demand diffracting and reflecting x-ray optics suitable for micro- and nano-focusing, brightness preservation, and super high resolution. One of the major impediments for development of x-ray optics with the required beamline performance comes from the inadequate present level of optical and at-wavelength metrology and insufficient integration of the metrology into the fabrication process and into beamlines. Based on our experience at the ALS Optical Metrology Laboratory, we review the experimental methods and techniques that allow us to mitigate significant optical metrology problems related to random, systematic, and drift errors with super-high-quality x-ray optics. Measurement errors below 0.2 mu rad have become routine. We present recent results from the ALS of temperature stabilized nano-focusing optics and dedicated at-wavelength metrology. The international effort to develop a next generation Optical Slope Measuring System (OSMS) to address these problems is also discussed. Finally, we analyze the remaining obstacles to further improvement of beamline x-ray optics and dedicated metrology, and highlight the ways we see to overcome the problems.

Yashchuk, Valeriy V.; Anderson, Erik H.; Barber, Samuel K.; Cambie, Rossana; Celestre, Richard; Conley, Raymond; Goldberg, Kenneth A.; McKinney, Wayne R.; Morrison, Gregory; Takacs, Peter Z.; Voronov, Dmitriy L.; Yuan, Sheng; Padmore, Howard A.

2010-07-09

400

Chapter 1 - The Impacts of X-Ray Absorption Spectroscopy on Understanding Soil Processes and Reaction Mechanisms  

SciTech Connect

During the last two decades, X-ray absorption spectroscopy (XAS) has developed into a mature technique for obtaining the speciation (e.g., oxidation state) and short-range structure of elements present in soils and sediments. XAS encompasses both X-ray absorption near-edge structure (XANES) spectroscopy and extended X-ray absorption fine structure (EXAFS) spectroscopy. XAS has a number of advantageous qualities for studying soils and sediments, which include elemental specificity, sensitivity to the local chemical and structural state of an element, and the ability to analyze materials in situ. This information allows accurate determination of oxidation state, type of nearest neighbors, coordination number, bond distance, and orbital symmetries of the X-ray absorbing element. In this review, we examine the application of a wide variety of synchrotron X-ray techniques to fundamental issues in environmental soil chemistry. Additionally, we examine the application of microfocused and time-resolved XAS to determine speciation (e.g., oxidation state and/or local coordination environment) and transformation kinetics of contaminants in heterogeneous environmental systems. During the last three decades, XAS has a played a critical role in furthering our understanding of a myriad of environmental systems and will continue to do so into the foreseeable future.

Ginder-Vogel, Matthew; Sparks, Donald L. (Delaware)

2011-11-17

401

Advanced signal separation and recovery algorithms for digital x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray spectroscopy is widely used for in-situ applications for samples analysis. Therefore, spectrum drawing and assessment of x-ray spectroscopy with high accuracy is the main scope of this paper. A Silicon Lithium Si(Li) detector that cooled with a nitrogen is used for signal extraction. The resolution of the ADC is 12 bits. Also, the sampling rate of ADC is 5 MHz. Hence, different algorithms are implemented. These algorithms were run on a personal computer with Intel core TM i5-3470 CPU and 3.20 GHz. These algorithms are signal preprocessing, signal separation and recovery algorithms, and spectrum drawing algorithm. Moreover, statistical measurements are used for evaluation of these algorithms. Signal preprocessing based on DC-offset correction and signal de-noising is performed. DC-offset correction was done by using minimum value of radiation signal. However, signal de-noising was implemented using fourth order finite impulse response (FIR) filter, linear phase least-square FIR filter, complex wavelet transforms (CWT) and Kalman filter methods. We noticed that Kalman filter achieves large peak signal to noise ratio (PSNR) and lower error than other methods. However, CWT takes much longer execution time. Moreover, three different algorithms that allow correction of x-ray signal overlapping are presented. These algorithms are 1D non-derivative peak search algorithm, second derivative peak search algorithm and extrema algorithm. Additionally, the effect of signal separation and recovery algorithms on spectrum drawing is measured. Comparison between these algorithms is introduced. The obtained results confirm that second derivative peak search algorithm as well as extrema algorithm have very small error in comparison with 1D non-derivative peak search algorithm. However, the second derivative peak search algorithm takes much longer execution time. Therefore, extrema algorithm introduces better results over other algorithms. It has the advantage of recovering and measuring over 21,941 peaks. Although, 1D non-derivative peak search algorithm has better extraction of peak height than other algorithms.

Mahmoud, Imbaby I.; El Tokhy, Mohamed S.

2015-02-01

402

Construction of a high-energy Bonse-Hart ultrasmall-angle x-ray scattering instrument  

NASA Astrophysics Data System (ADS)

A Bonse-Hart ultrasmall-angle x-ray scattering (USAXS) instrument, employing a synchrotron x-ray source at an energy of 18.86 keV (wavelength ?=0.06573 nm), has been designed, constructed, and tested. Solid as well as suspensions of polystyrene and poly(chlorostyrene) latex spheres were used as reference standards in order to demonstrate the range of this instrument. The USAXS results measured at ?=0.06573 nm were also compared with those from a calibrated Bonse-Hart instrument operating at ?=0.154 nm, i.e., the standard Cu K? radiation. The higher-energy synchrotron x rays permit us to study absorbing and/or opaque materials having long range inhomogeneities in the order of microns. Furthermore, for many polymer systems, the optimal sample thickness at ??0.066 nm is increased to ˜10 mm and thin-walled glass windows become acceptable. Thus, a cylindrical light-scattering cell with a wall thickness of 0.3 mm could be used for both USAXS and laser light scattering measurements. The main hurdle for performing simultaneous static and dynamic light scattering as well as USAXS experiments on polymer solutions and gels with the same sample has been resolved. This capability should open up new frontiers in structural and dynamical studies of systems involving a large range of length scales from angstroms to microns.

Chu, Benjamin; Yeh, Fengji; Li, Yingjie; Harney, Paul J.; Rousseau, Jean; Darovsky, Alex; Siddons, D. P.

1994-10-01

403

Oxidation and surface segregation of chromium in Fe-Cr alloys studied by Mössbauer and X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The room temperature 57Fe Mössbauer and XPS spectra were measured for polycrystalline iron-based Fe-Cr alloys. The spectra were collected using three techniques: the transmission Mössbauer spectroscopy (TMS), the conversion electron Mössbauer spectroscopy (CEMS) and the X-ray photoelectron spectroscopy (XPS). The combination of these experimental techniques allows to determine changes in Cr concentration and the presence of oxygen in bulk, in the 300 nm pre-surface layer and on the surface of the studied alloys.

Idczak, R.; Idczak, K.; Konieczny, R.

2014-09-01

404

Characterization of Sb-doped Bi(2)UO(6) solid solutions by X-ray diffraction and X-ray absorption spectroscopy.  

PubMed

The preparation and characterization of Sb-doped Bi(2)UO(6) solid solutions, in a limited composition range, is reported for the first time. The solid solutions were prepared by solid-state reactions of Bi(2)O(3), Sb(2)O(3) and U(3)O(8) in the required stoichiometry. The reaction products were characterized by X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS) measurements at the Bi and U L(3) edges. The XRD patterns indicate the precipitation of additional phases in the samples when Sb doping exceeds 4 at%. The chemical shifts of the Bi absorption edges in the samples, determined from the XANES spectra, show a systematic variation only up to 4 at% of Sb doping and support the results of XRD measurements. These observations are further supported by the local structure parameters obtained by analysis of the EXAFS spectra. The local structure of U is found to remain unchanged upon Sb doping indicating that Sb(+3) ions replace Bi(+3) during the doping of Bi(2)UO(6) by Sb. PMID:23665633

Misra, N L; Yadav, A K; Dhara, Sangita; Mishra, S K; Phatak, Rohan; Poswal, A K; Jha, S N; Sinha, A K; Bhattacharyya, D

2013-01-01

405

High-Resolution X-Ray Spectroscopy at the National Spherical Torus Experiment (NSTX)  

NASA Astrophysics Data System (ADS)

Two high-resolution imaging X-ray crystal spectrometers, which record spectra of heliumlike argon and provide spatially and temporally resolved data on the ion temperature, toroidal and poloidal plasma rotation, electron temperature, and impurity ion-charge state distribution, have recently been proposed as diagnostics for NSTX (ref. 1). One of the spectrometers is now under construction and expected to be operational during the upcoming experimental campaign. The instrument will supply data for practically all NSTX discharges, including plasmas with pure ohmic heating, rf heating and neutral beam injection, due to the fact that heliumlike argon is the dominant charge state for electron temperatures in the range from 0.4 to 3.0 keV. The instrumental design is similar to the design of the already operating spectrometers at TEXTOR-94. The paper will present the instrumental parameters and recent experimental results from NSTX and TEXTOR-94. *This work is supported by DOE Contract No. DE-AC02-CH0-3073. (1) M. Bitter et al. Rev. Sci. Instrum. 70, 292 (1999).

Bitter, Manfred; Hill, Kenneth; Roquemore, Lane; von Goeler, Schweickhardt; Bertschinger, Günter; Weinheimer, Jeff

1999-11-01

406

Electronic band structure of graphene from resonant soft x-ray spectroscopy: The role of core-hole effects  

NASA Astrophysics Data System (ADS)

The electronic structure and band dispersion of graphene on SiO2 have been studied by x-ray-absorption spectroscopy (XAS), x-ray-emission spectroscopy (XES), and resonant inelastic x-ray scattering (RIXS). Using first-principles calculations, it is found that the core-hole effect is dramatic in XAS while it has negligible consequences in XES. Strong dispersive features, due to the conservation of crystal momentum, are observed in RIXS spectra. Simulated RIXS spectra based on the Kramers-Heisenberg theory agree well with the experimental results, provided a shift between RIXS and XAS due to the absence or presence of the core hole is taken into account.

Zhang, L.; Schwertfager, N.; Cheiwchanchamnangij, T.; Lin, X.; Glans-Suzuki, P.-A.; Piper, L. F. J.; Limpijumnong, S.; Luo, Y.; Zhu, J. F.; Lambrecht, W. R. L.; Guo, J.-H.

2012-12-01

407

Electronic structure of the organic semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from soft x-ray spectroscopies and density functional theory calculations.  

PubMed

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq(3)) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq(3), and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former. PMID:19071937

DeMasi, A; Piper, L F J; Zhang, Y; Reid, I; Wang, S; Smith, K E; Downes, J E; Peltekis, N; McGuinness, C; Matsuura, A

2008-12-14

408

Electronic Structure of the Organic Semiconductor Alq3 (aluminum tris-8-hydroxyquinoline) from Soft X-ray Spectroscopies and Density Functional Theory Calculations  

SciTech Connect

The element-specific electronic structure of the organic semiconductor aluminum tris-8-hydroxyquinoline (Alq3) has been studied using a combination of resonant x-ray emission spectroscopy, x-ray photoelectron spectroscopy, x-ray absorption spectroscopy, and density functional theory (DFT) calculations. Resonant and nonresonant x-ray emission spectroscopy were used to measure directly the carbon, nitrogen and oxygen 2p partial densities of states in Alq3, and good agreement was found with the results of DFT calculations. Furthermore, resonant x-ray emission at the carbon K-edge is shown to be able to measure the partial density of states associated with individual C sites. Finally, comparison of previous x-ray emission studies and the present data reveal the presence of clear photon-induced damage in the former.

DeMasi, A.; Piper, L; Zhang, Y; Reid, I; Wang, S; Smith, K; Downes, J; Pelkekis, N; McGuinness, C; Matsuura, A

2008-01-01

409

A multi-wavelength view of AB Doradus outer atmosphere . Simultaneous X-ray and optical spectroscopy at high cadence  

NASA Astrophysics Data System (ADS)

Aims: We study the chromosphere and corona of the ultra-fast rotator AB Dor A at high temporal and spectral resolution using simultaneous observations with XMM-Newton in the X-rays, VLT/UVES in the optical, and the ATCA in the radio. Our optical spectra have a resolving power of ~50 000 with a time cadence of ~1 min. Our observations continuously cover more than one rotational period and include both quiescent periods and three flaring events of different strengths. Methods: From the X-ray observations we investigated the variations in coronal temperature, emission measure, densities, and abundance. We interpreted our data in terms of a loop model. From the optical data we characterised the flaring chromospheric material using numerous emission lines that appear in the course of the flares. A detailed analysis of the line shapes and line centres allowed us to infer physical characteristics of the flaring chromosphere and to coarsely localise the flare event on the star. Results: We specifically used the optical high-cadence spectra to demonstrate that both turbulent and Stark broadening are present during the first ten minutes of the first flare. Also, in the first few minutes of this flare, we find short-lived (one to several minutes) emission subcomponents in the H? and Ca ii K lines, which we interpret as flare-connected shocks owing to their high intrinsic velocities. Combining the space-based data with the results of our optical spectroscopy, we derive flare-filling factors. Finally, comparing X-ray, optical broadband, and line emission, we find a correlation for two of the three flaring events, while there is no clear correlation for one event. Also, we do not find any correlation of the radio data to any other observed data. Based on observations collected at the European Southern Observatory, Paranal, Chile, 383.D-1002A and on observations obtained with XMM-Newton, an ESA science mission with instruments and contributions directly funded by ESA member states and NASA.Full Table 6 and reduced data are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/560/A69

Lalitha, S.; Fuhrmeister, B.; Wolter, U.; Schmitt, J. H. M. M.; Engels, D.; Wieringa, M. H.

2013-12-01

410

EUV, X-ray, and Gamma-ray instrumentation for astronomy; Proceedings of the Meeting, San Diego, CA, July 11-13, 1990  

NASA Astrophysics Data System (ADS)

Various papers on EUV, X-ray, and gamma-ray instrumentation for astronomy are presented. Individual topics addressed include: performance of lithium scatterers for X-ray polarimetry, shared X-ray concentration via crystal diffraction, optimum shields for spaceborne gamma-ray spectrometers, position-sensitive high-resolution spectrometer, IPCs for stellar X-ray polarimeter, soft X-ray windows for position-sensitive proportional counters, EUV imaging telescope array on the spectrum X-G satellite, European Photon Imaging Camera for X-ray astronomy, development of a UV auroral imager, background reduction in microchannel plates, 2D delay-line anode detector for astronomical imaging, dynamic range considerations for EUV MAMA detectors, Rosat WFD imaging detectors. Also discussed are: EUV band-pass filters for the Rosat wide-field camera, calibration of the Rosat High-Resolution Imager, superconducting tunneling junction detectors, test results of a prototype dielectric microcalorimeter, novel high-speed high-resolution position readout SPAN, after emission in microchannel plate detectors, highly curved microchannel plates, soft X-ray performance of back-illuminated EEV CCDs, proton damage effects in EEV CCDs, PN-CCDs for the XMM satellite mission, intensified CCD detectors using the phosphor TPB, silicon X-ray array detector concept, multilayer telescope for soft X-ray surveys, hard X-ray and soft gamma-ray astronomy mission EXOS.

Siegmund, Oswald H. W.; Hudson, Hugh S.

1990-11-01

411

High resolution x-ray spectroscopy using GaAs arrays  

NASA Astrophysics Data System (ADS)

We have produced a number of small format gallium arsenide (GaAs) arrays to address the material, electronic, and technological problems that need to be solved in order to develop mega pixel, Fano-limited spectroscopic x-ray imagers. Results will be presented of a series of x-ray measurements carried out on a prototype 5×5 array, fabricated from 40 ?m thick epitaxial GaAs. The device has pixel sizes of 200×200 ?m2 and pitch 250 ?m. As a preliminary investigation of performance, two pixels have been instrumented. Measurements from 5.9 to 98 keV were carried out both in our laboratory and at the Hamburger Synchrotronstrahlungslabor research facility in Hamburg, Germany. Both pixels were found to be remarkably uniform, both in their spectral and spatial response to x-rays. The average nonlinearity in the spectral response is <1% across the energy range 5.9-98 keV. Using a 12 keV, 20×20 ?m2 pencil beam, the spatial uniformity was found to be better than 98% over the entire pixel surfaces, consistent with the statistical precision of the measurement. The energy resolution at -40 °C is 400 eV full width at half maximum (FWHM) at 5.9 keV rising to 700 eV FWHM at 98 keV. No difference in energy resolution was found between full area and pencil beam illumination. An analysis of the resolution function has shown that the detector is dominated by electronic noise at low energies and Fano noise at energies above 30 keV. By best-fitting the expected resolution function to the entire data set, we derive a Fano factor of 0.140±0.05, together with a charge transport factor as low as 1.4×10-3. Further improvement in the resolution function has been achieved by replacing the conventional resistive feedback preamplifiers with a new resistorless design, which provides a lower component of electronic noise. In this case, a resolution of 266 eV FWHM at 5.9 keV has been achieved at room temperature (23 °C) and 219 eV FWHM with only modest cooling (-31 °C). The expected Fano noise at this energy is ˜140 eV.

Owens, Alan; Bavdaz, M.; Peacock, A.; Poelaert, A.; Andersson, H.; Nenonen, S.; Sipila, H.; Tröger, L.; Bertuccio, G.

2001-11-01

412

Studies of Element-Specific Local Structures in Compound Materials Using X-Ray Absorption Spectroscopy  

NASA Astrophysics Data System (ADS)

The x-ray absorption spectroscopy techniques have been used to study a variety of semiconductor and superconductor materials. In such experiments, synchrotron radiation harnessed by a delicate beamline electronic and control system are used to obtain data with analyzable quality in a reasonable time scale. The element-selectivity is achieved by selecting an energy-scan range close to a characteristic "absorption edge" of the selected element. Peak structures below the absorption edge (pre-edge structures) reflect the local unoccupied states of the selected atomic species. The position of absorption edge (part of the near-edge x-ray absorption fine structure, NEXAFS) provides some qualitative information of the effective valency of the selected element. And, most importantly, the modulation in the spectrum some 40 eV above the absorption edge (extended x-ray absorption fine structure, EXAFS) gives quantitative information of the local structure around the selected atomic species. The selected atomic species such as magnetic Mn ions in III-V diluted magnetic semiconductors (DMS) rm In_{1-x}Mn_{x}As, Mn as the luminescent centers in nanocrystals of ZnS, O in the CuO_2 planes which host the carriers in high-T_{rm c} superconductors, and F as the electron reservoir in the n-type high-T_{rm c} superconductors rm Nd_2CuO _{4-x}F_{x} all play an important role in the novel mechanism of these new materials. Along with other detailed information, our EXAFS results have revealed (i) III-V DMS can indeed be prepared by substitutional doping of magnetic impurities under proper processing conditions. (ii) Mn ions substitute for the Zn sites in the nanocrystals of ZnS with significant size-dependent local structural changes. (iii) Only ~6% of O in the CuO_2 planes in rm Nd_2CuO_{4 -x}F_{x} are substituted by F. The rest of F atoms substitute for O atoms in the NdO layers and serve as electron reservoirs. The NEXAFS results have shown that the effective valency of Mn in ZnS nanocrystals is close to +2 with a weak size dependence. And, our pre -edge structure analysis has confirmed the importance of O 2p holes in the high-T_{rm c} superconductor mechanism.

Soo, Yun-Liang

1995-01-01

413

Microbeam x-ray absorption spectroscopy study of chromium in large-grain uranium dioxide fuel.  

PubMed

Synchrotron-based microprobe x-ray absorption spectroscopy (XAS) has been used to study the local atomic structure of chromium in chromia-doped uranium dioxide (UO2) grains. The specimens investigated were a commercial grade chromia-doped UO2 fresh fuel pellet, and materials from a spent fuel pellet of the same batch, irradiated with an average burnup of ~40 MW d kg(-1). Uranium L3-edge and chromium K-edge XAS have been measured, and the structural environments of central uranium and chromium atoms have been elucidated. The Fourier transform of uranium L3-edge extended x-ray absorption fine structure shows two well-defined peaks of U-O and U-U bonds at average distances of 2.36 and 3.83 Å. Their coordination numbers are determined as 8 and 11, respectively. The chromium Fourier transform extended x-ray absorption fine structure of the pristine UO2 matrix shows similar structural features with the corresponding spectrum of the irradiated spent fuel, indicative of analogous chromium environments in the two samples studied. From the chromium XAS experimental data, detectable next neighbor atoms are oxygen and uranium of the cation-substituted UO2 lattice, and two distinct subshells of chromium and oxygen neighbors, possibly because of undissolved chromia particles present in the doped fuels. Curve-fitting analyses using theoretical amplitude and phase-shift functions of the closest Cr-O shell and calculations with ab initio computer code FEFF and atomic clusters generated from the chromium-dissolved UO2 structure have been carried out. There is a prominent reduction in the length of the adjacent Cr-O bond of about 0.3 Å in chromia-doped UO2 compared with the ideal U-O bond length in standard UO2 that would be expected because of the change in effective Coulomb interactions resulting from replacing U(4+) with Cr(3+) and their ionic size differences. The contraction of shortest Cr-U bond is ~0.1?Å relative to the U-U bond length in bulk UO2. The difference in the local chromium environment between fresh and irradiated UO2 is discussed based on the comparison of quantitative structural information obtained from the two chromia-doped fuel samples analyzed. PMID:25109302

Mieszczynski, C; Kuri, G; Bertsch, J; Martin, M; Borca, C N; Delafoy, Ch; Simoni, E

2014-09-01

414

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

SciTech Connect

Spectroscopic studies on heterogeneous catalysts have mostly been done in an integral mode. However, in many cases spatial variations in catalyst structure can occur, e.g. during impregnation of pre-shaped particles, during reaction in a catalytic reactor, or in microstructured reactors as the present overview shows. Therefore, spatially resolved molecular information on a microscale is required for a comprehensive understanding of theses systems, partly in ex situ studies, partly under stationary reaction conditions and in some cases even under dynamic reaction conditions. Among the different available techniques, X-ray absorption spectroscopy (XAS) is a well-suited tool for this purpose as the different selected examples highlight. Two different techniques, scanning and full-field X-ray microscopy/tomography, are described and compared. At first, the tomographic structure of impregnated alumina pellets is presented using full-field transmission microtomography and compared to the results obtained with a scanning X-ray microbeam technique to analyse the catalyst bed inside a catalytic quartz glass reactor. On the other hand, by using XAS in scanning microtomography, the structure and the distribution of Cu(0), Cu(I), Cu(II) species in a Cu/ZnO catalyst loaded in a quartz capillary microreactor could be reconstructed quantitatively on a virtual section through the reactor. An illustrating example for spatially resolved XAS under reaction conditions is the partial oxidation of methane over noble metal-based catalysts. In order to obtain spectroscopic information on the spatial variation of the oxidation state of the catalyst inside the reactor XAS spectra were recorded by scanning with a micro-focussed beam along the catalyst bed. Alternatively, full-field transmission imaging was used to efficiently determine the distribution of the oxidation state of a catalyst inside a reactor under reaction conditions. The new technical approaches together with quantitative data analysis and an appropriate in situ catalytic experiment allowed drawing important conclusions on the reaction mechanism, and the analytical strategy might be similarly applied in other case studies. The corresponding temperature profiles and the catalytic performance were measured by means of an IR-camera and mass spectrometric analysis. In a more advanced experiment the ignition process of the partial oxidation of methane was followed in a spatiotemporal manner which demonstrates that spatially resolved spectroscopic information can even be obtained in the subsecond scale.

Grunwaldt, Jan-Dierk; Kimmerle, Bertram; Baiker, Alfons; Boye, Pit; Schroer, Christian G.; Glatzel, Pieter; Borca, Camelia N.; Beckmann, Felix; (TUD); (SLS); (IMR-GAC); (ETH Zurich); (ESRF); (TU Dresden)

2009-09-25

415

Microbeam x-ray absorption spectroscopy study of chromium in large-grain uranium dioxide fuel  

NASA Astrophysics Data System (ADS)

Synchrotron-based microprobe x-ray absorption spectroscopy (XAS) has been used to study the local atomic structure of chromium in chromia-doped uranium dioxide (UO2) grains. The specimens investigated were a commercial grade chromia-doped UO2 fresh fuel pellet, and materials from a spent fuel pellet of the same batch, irradiated with an average burnup of ~40?MW d kg-1. Uranium L3-edge and chromium K-edge XAS have been measured, and the structural environments of central uranium and chromium atoms have been elucidated. The Fourier transform of uranium L3-edge extended x-ray absorption fine structure shows two well-defined peaks of U-O and U-U bonds at average distances of 2.36 and 3.83?Å. Their coordination numbers are determined as 8 and 11, respectively. The chromium Fourier transform extended x-ray absorption fine structure of the pristine UO2 matrix shows similar structural features with the corresponding spectrum of the irradiated spent fuel, indicative of analogous chromium environments in the two samples studied. From the chromium XAS experimental data, detectable next neighbor atoms are oxygen and uranium of the cation-substituted UO2 lattice, and two distinct subshells of chromium and oxygen neighbors, possibly because of undissolved chromia particles present in the doped fuels. Curve-fitting analyses using theoretical amplitude and phase-shift functions of the closest Cr-O shell and calculations with ab initio computer code FEFF and atomic clusters generated from the chromium-dissolved UO2 structure have been carried out. There is a prominent reduction in the length of the adjacent Cr-O bond of about 0.3?Å in chromia-doped UO2 compared with the ideal U-O bond length in standard UO2 that would be expected because of the change in effective Coulomb interactions resulting from replacing U4+ with Cr3+ and their ionic size differences. The contraction of shortest Cr-U bond is ~0.1?Å relative to the U-U bond length in bulk UO2. The difference in the local chromium environment between fresh and irradiated UO2 is discussed based on the comparison of quantitative structural information obtained from the two chromia-doped fuel samples analyzed.

Mieszczynski, C.; Kuri, G.; Bertsch, J.; Martin, M.; Borca, C. N.; Delafoy, Ch; Simoni, E.

2014-09-01

416

X-ray scattering and spectroscopy studies on diesel soot from oxygenated fuel under various engine load conditions  

USGS Publications Warehouse

Diesel soot from reference diesel fuel and oxygenated fuel under idle and load engine conditions was investigated with X-ray scattering and X-ray carbon K-edge absorption spectroscopy. Up to five characteristic size ranges were found. Idle soot was generally found to have larger primary particles and aggregates but smaller crystallites, than load soot. Load soot has a higher degree of crystallinity than idle soot. Adding oxygenates to diesel fuel enhanced differences in the characteristics of diesel soot, or even reversed them. Aromaticity of idle soot from oxygenated diesel fuel was significantly larger than from the corresponding load soot. Carbon near-edge X-ray absorption fine structure (NEXAFS) spectroscopy was applied to gather information about the presence of relative amounts of carbon double bonds (CC, CO) and carbon single bonds (C-H, C-OH, COOH). Using scanning X-ray transmission microspectroscopy (STXM), the relative amounts of these carbon bond states were shown to vary spatially over distances approximately 50 to 100 nm. The results from the X-ray techniques are supported by thermo-gravimetry analysis and high-resolution transmission electron microscopy. ?? 2005 Elsevier Ltd. All rights reserved.

Braun, A.; Shah, N.; Huggins, F.E.; Kelly, K.E.; Sarofim, A.; Jacobsen, C.; Wirick, S.; Francis, H.; Ilavsky, J.; Thomas, G.E.; Huffman, G.P.

2005-01-01

417

Simultaneous measurements of small angle x-ray scattering, wide angle x-ray scattering, and dielectric spectroscopy during crystallization of polymers  

NASA Astrophysics Data System (ADS)

A novel experimental setup is described which allows one to obtain detailed information on structural and dynamical changes in polymers during crystallization. This technique includes simultaneous measurements of small angle-wide angle x-ray scattering and dielectric spectroscopy (SWD). The capabilities of the technique have been probed by following in real time the crystallization process of a model crystallizable polymer: poly(ethylene terephthalate). By performing these experiments, simultaneous information from both, the amorphous and the crystalline phase is obtained providing a complete description of changes occurring during a crystallization process. The SWD technique opens up new promising perspectives for the experimental study of the relation between structure and dynamics in materials science.

Šics, I.; Nogales, A.; Ezquerra, T. A.; Denchev, Z.; Baltá-Calleja, F. J.; Meyer, A.; Döhrmann, R.

2000-04-01

418

Simultaneous measurements of small angle X-ray scattering, wide angle x-ray scattering, and dielectric spectroscopy during crystallization of polymers  

NASA Astrophysics Data System (ADS)

A novel experimental set-up is described which allows one to obtain detailed information on simultaneous structural and dynamical changes in polymers during crystallization. This technique involves simultaneous measurements of small angle - wide angle X-ray scattering and dielectric spectroscopy(SWD). The capabilities of the technique have been probed by following in real time the crystallization process of a model crystallisable polymer: poly(ethylene terephthalate). From these experiments, simultaneous information from both, the amorphous and the crystalline phase is obtained. The results provide a more complete description of changes occurring during a crystallization process. The SWD technique opens up new promising perspectives for the experimental study of the relation between structure and dynamics in materials science.

Ezquerra, T. A.; Sics, I.; Nogales, A.; Denchev, Z.; Baltá-Calleja, F. J.

2000-03-01

419

A Fast, Versatile Nanoprobe for Complex Materials: The Sub-micron Resolution X-ray Spectroscopy Beamline at NSLS-II (491st Brookhaven Lecture)  

SciTech Connect

Time is money and for scientists who need to collect data at research facilities like Brookhaven Lab’s National Synchrotron Light Source (NSLS), “beamtime” can be a precious commodity. While scanning a complex material with a specific technique and standard equipment today would take days to complete, researchers preparing to use brighter x-rays and the new sub-micron-resolution x-ray spectroscopy (SRX) beamline at the National Synchrotron Light Source II (NSLS-II) could scan the same sample in greater detail with just a few hours of beamtime. Talk about savings and new opportunities for researchers! Users will rely on these tools for locating trace elements in contaminated soils, developing processes for nanoparticles to deliver medical treatments, and much more. Dr. Thieme explains benefits for next-generation research with spectroscopy and more intense x-rays at NSLS-II. He discusses the instrumentation, features, and uses for the new SRX beamline, highlighting its speed, adjustability, and versatility for probing samples ranging in size from millimeters down to the nanoscale. He will talk about complementary beamlines being developed for additional capabilities at NSLS-II as well.

Thieme, Juergen [BNL Photon Sciences Directorate

2014-02-06

420

Dip Spectroscopy of the Low Mass X-Ray Binary XB 1254-690  

NASA Technical Reports Server (NTRS)

We observed the low mass X-ray binary XB 1254-690 with the Rossi X-ray Timing Explorer in 2001 May and December. During the first observation strong dipping on the 3.9-hr orbital period and a high degree of variability were observed, along with "shoulders" approx. 15% deep during extended intervals on each side of the main dips. The first observation also included pronounced flaring activity. The non-dip spectrum obtained using the PCA instrument was well-described by a two-component model consisting of a blackbody with kT = 1.30 +/- 0.10 keV plus a cut-off power law representation of Comptonized emission with power law photon index 1.10 +/- 0.46 and a cut-off energy of 5.9(sup +3.0, sub -1.4) keV. The intensity decrease in the shoulders of dipping is energy-independent, consistent with electron scattering in the outer ionized regions of the absorber. In deep dipping the depth of dipping reached 100%, in the energy band below 5 keV, indicating that all emitting regions were covered by absorber. Intensity-selected dip spectra were well-fit by a model in which the point-like blackbody is rapidly covered, while the extended Comptonized emission is progressively overlapped by the absorber, with the, covering fraction rising to 95% in the deepest portion of the dip. The intensity of this component in the dip spectra could be modeled by a combination of electron scattering and photoelectric absorption. Dipping did not occur during the 2001 December observation, but remarkably, both bursting and flaring were observed contemporaneously.

Smale, Alan P.; Church, M. J.; BalucinskaChurch, M.; White, Nicholas E. (Technical Monitor)

2002-01-01

421

Incorporation of arsenic in mammal bone: X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy (XAS) of the distal tibia of a modern deer, Odocoileus virginianus, revealed that the energy position of the As K edge matched that of a reference arsenic(V) model compound. Comparison of the x-ray absorption near edge structure (XANES) of the deer spectrum to the spectra of model As compounds indicated a close match to arsenate(V), e.g., zinc orthoarsenate(5). This indicates that the nearest-neighbor shell of the arsenic in the bone consists of four oxygens in the tetrahedral arrangement typical of arsenic(V) oxysalts. The XANES analysis demonstrates that the arsenic in the deer bone is not associated with an organic compound as a result of methylation. This suggests that the arsenic is associated with the mineral fraction of the bone, most likely with As substituting for P at the latter's structural site in the hydroxyapatite. The XAS data for the deer bone were very noisy due to the low level of arsenic present, just over 1 ppm.. A total of 18 scans, taking nearly a full 8-hour beam shift, were averaged to obtain the spectrum studied. It is not clear that the second neighbor shell can be characterized sufficiently from these data to confirm that As substitutes for P in hydroxyapatite. We conducted our XAS experiments on beam line 4-3 at the Stanford Synchrotron Radiation Laboratory. Data were collected in the fluorescence mode, using a solid state, 13-element Ge-detector. The energy reference was As(0) metal foil run parasitically in transmission mode during collection of the bone spectra. The edge shift seen in the experimental and As(V) model compound relative to the energy position of the arsenic(0) foil is consistent with the additional energy required to photoeject the 1-s electron of As(V), relative to that required for As(0). Arsenic content of the deer bone was determined by inductively coupled plasma mass spectrometry.

Kretschmer, X.; Pingitore, N. E.; Cruz-Jimenez, G.

2002-12-01

422

Au36(SPh)24 nanomolecules: X-ray crystal structure, optical spectroscopy, electrochemistry, and theoretical analysis.  

PubMed

The physicochemical properties of gold:thiolate nanomolecules depend on their crystal structure and the capping ligands. The effects of protecting ligands on the crystal structure of the nanomolecules are of high interest in this area of research. Here we report the crystal structure of an all aromatic thiophenolate-capped Au36(SPh)24 nanomolecule, which has a face-centered cubic (fcc) core similar to other nanomolecules such as Au36(SPh-tBu)24 and Au36(SC5H9)24 with the same number of gold atoms and ligands. The results support the idea that a stable core remains intact even when the capping ligand is varied. We also correct our earlier assignment of "Au36(SPh)23" which was determined based on MALDI mass spectrometry which is more prone to fragmentation than ESI mass spectrometry. We show that ESI mass spectrometry gives the correct assignment of Au36(SPh)24, supporting the X-ray crystal structure. The electronic structure of the title compound was computed at different levels of theory (PBE, LDA, and LB94) using the coordinates extracted from the single crystal X-ray diffraction data. The optical and electrochemical properties were determined from experimental data using UV-vis spectroscopy, cyclic voltammetry, and differential pulse voltammetry. Au36(SPh)24 shows a broad electrochemical gap near 2 V, a desirable optical gap of ?1.75 eV for dye-sensitized solar cell applications, as well as appropriately positioned electrochemical potentials for many electrocatalytic reactions. PMID:25315687

Nimmala, Praneeth Reddy; Knoppe, Stefan; Jupally, Vijay Reddy; Delcamp, Jared H; Aikens, Christine M; Dass, Amala

2014-12-11

423

X-ray Photoelectron Spectroscopy Study of Argon-Plasma-Treated Fluoropolymers  

NASA Technical Reports Server (NTRS)

Films of poly(tetrafluoroethylene) (PTFE) and of a tetrafluoroethylene-perfluoroalkyl vinyl ether (approximately 49:1) copolymer (PFA) were exposed to a radio-frequency argon plasma and then examined by X-ray photoelectron spectroscopy (XPS). The use of fluoropolymer films nearly free of surface hydrocarbon contamination as well as the use of a monochromatized X-ray source for XPS removed two factors contributing to conflicting reports on the effect of exposure time on the fluorine-to-carbon (F/C) and oxygen-to-carbon (O/C) ratios for several Ar-plasma-treated fluoropolymers. Contrary to literature indications, a common pattern was found for PTFE and PFA: a moderate decrease in F/C ratio (from 1.99 to 1.40, and from 1.97 to 1.57, respectively), together with a moderate increase in O/C ratio (from negligible to about 0.10, and from 0.012 to about O.10, respectively) at very short exposures, after which the F/C ratios remained essentially constant on prolonged exposures, while the O/C ratios for PTFE and PFA leveled off at 0.11 and 0.15, respectively. The XPS C(sub 1s), spectra for these polymers exposed to the Ar plasma for 20 min were similar and presented, besides a prominent peak at 292.0 eV (CF2,) and a minor peak at 294.0 or 294.1 eV (CF3), a composite band of four curve-resolved peaks (approximately 285-290 eV) representing various CH, CC, CO, CN, and CF functionalities.

Golub, Morton A.; Lopata, Eugene S.; Finney, Lorie S.

1994-01-01

424

Profiling of the SiO2 -SiC Interface Using X-ray Photoelectron Spectroscopy R. N. Ghosh  

E-print Network

oxides on 4H-SiC single crystal substrates. The C 1s spectrum suggests the presence of a graphi