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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

The new ambient-pressure X-ray photoelectron spectroscopy instrument at MAX-lab.  

PubMed

The new instrument for near-ambient-pressure X-ray photoelectron spectroscopy which has been installed at the MAX II ring of the Swedish synchrotron radiation facility MAX IV Laboratory in Lund is presented. The new instrument, which is based on a SPECS PHOIBOS 150 NAP analyser, is the first to feature the use of retractable and exchangeable high-pressure cells. This implies that clean vacuum conditions are retained in the instrument's analysis chamber and that it is possible to swiftly change between near-ambient and ultrahigh-vacuum conditions. In this way the instrument implements a direct link between ultrahigh-vacuum and in situ studies, and the entire pressure range from ultrahigh-vacuum to near-ambient conditions is available to the user. Measurements at pressures up to 10(-5)?mbar are carried out in the ultrahigh-vacuum analysis chamber, while measurements at higher pressures are performed in the high-pressure cell. The installation of a mass spectrometer on the exhaust line of the reaction cell offers the users the additional dimension of simultaneous reaction data monitoring. Moreover, the chosen design approach allows the use of dedicated cells for different sample environments, rendering the Swedish ambient-pressure X-ray photoelectron spectroscopy instrument a highly versatile and flexible tool. PMID:22898948

Schnadt, Joachim; Knudsen, Jan; Andersen, Jesper N; Siegbahn, Hans; Pietzsch, Annette; Hennies, Franz; Johansson, Niclas; Mårtensson, Nils; Ohrwall, Gunnar; Bahr, Stephan; Mähl, Sven; Schaff, Oliver

2012-09-01

3

New instrumentation for micro-imaging X-ray absorption spectroscopy using optical detection methods  

NASA Astrophysics Data System (ADS)

The design and use of a novel portable synchrotron end-station is described, that allows for the micro-imaging of X-ray absorption features of solids, via their luminescence emission. This mode of measurement is possible on most standard synchrotron beamlines (i.e. not only those with dedicated optics to allow X-ray micro-imaging) and any excitation energy is usable, typically from the UV to hard X-rays, 4 eV to 70 keV. Furthermore, since the micro-imaging is obtained via optical detection of X-ray absorption, a direct link between the X-ray features and the luminescence characteristics of a sample is possible. The article describes both the technical aspects of the new instrument and some of its early uses in the XUV energy range on beamline MPW 6.1 (40-450 eV) at the UK's synchrotron radiation source at Daresbury.

Poolton, N. R. J.; Towlson, B. M.; Hamilton, B.; Evans, D. A.

2006-05-01

4

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

5

Soft X-ray microscopy with a cryo scanning transmission X-ray microscope: I. Instrumentation, imaging and spectroscopy  

Microsoft Academic Search

Summary We have developed a cryo scanning transmission X-ray microscope which uses soft X-rays from the National Synchrotron Light Source. The system is capable of imaging frozen hydrated specimens with a thickness of up to 10 mm at temperatures of around 100 K. We show images and spectra from frozen hydrated eukaryotic cells, and a demonstration that biological specimens do

Maser; Osanna; Kirz; Winn; Tennant

2000-01-01

6

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

SciTech Connect

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

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

2013-12-15

7

Tokamak x ray diagnostic instrumentation  

SciTech Connect

Three classes of x-ray diagnostic instruments enable measurement of a variety of tokamak physics parameters from different features of the x-ray emission spectrum. (1) The soft x-ray (1 to 50 keV) pulse-height-analysis (PHA) diagnostic measures impurity concentrations from characteristic line intensities and the continuum enhancement, and measures the electron temperature from the continuum slope. (2) The Bragg x-ray crystal spectrometer (XCS) measures the ion temperature and neutral-beam-induced toroidal rotation velocity from the Doppler broadening and wavelength shift, respectively, of spectral lines of medium-Z impurity ions. Impurity charge state distributions, precise wavelengths, and inner-shell excitation and recombination rates can also be studied. X rays are diffracted and focused by a bent crystal onto a position-sensitive detector. The spectral resolving power E/..delta..E is greater than 10/sup 4/ and time resolution is 10 ms. (3) The x-ray imaging system (XIS) measures the spatial structure of rapid fluctuations (0.1 to 100 kHZ) providing information on MHD phenomena, impurity transport rates, toroidal rotation velocity, plasma position, and the electron temperature profile. It uses an array of silicon surface-barrier diodes which view different chords of the plasma through a common slot aperture and operate in current (as opposed to counting) mode. The effectiveness of shields to protect detectors from fusion-neutron radiation effects has been studied both theoretically and experimentally.

Hill, K.W.; Beiersdorfer, P.; Bitter, M.; Fredrickson, E.; Von Goeler, S.; Hsuan, H.; Johnson, L.C.; Liew, S.L.; McGuire, K.; Pare, V.

1987-01-01

8

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

Microsoft Academic Search

Soft X-ray emission spectra (SXES) obtained using monochromatic synchrotron radiation (SR) provides important advantages as compared with electron excitation. Photons can penetrate deep into the sample providing nondestructive information from bulk samples. With availability of tunable monochromatic photons from synchrotron sources, it is now possible to selectively ionize core electrons near enough to the core level threshold energy producing singly

Rupert C. C. Perera

1992-01-01

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

Nuclear Instruments and Methods in Physics Research A 524 (2004) 287­294 Dead time and pileup presents a method that allows correction of dead time losses and pileup in pulsed X-ray spectroscopy electron beam currents. The method presented here uses the observed integrated count rate in a PXR peak

Danon, Yaron

10

X-ray astronomical spectroscopy  

NASA Technical Reports Server (NTRS)

The contributions of the Goddard group to the history of X-ray astronomy are numerous and varied. One role that the group has continued to play involves the pursuit of techniques for the measurement and interpretation of the X-ray spectra of cosmic sources. The latest development is the selection of the X-ray microcalorimeter for the Advanced X-ray Astrophysics Facility (AXAF) study payload. This technology is likely to revolutionize the study of cosmic X-ray spectra.

Holt, Stephen S.

1987-01-01

11

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

SciTech Connect

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

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

2008-06-17

12

Large Area X-ray Spectroscopy Mission  

NASA 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

13

X-ray Fluorescence Spectroscopy of Novel Materials  

Microsoft Academic Search

This review focuses on the capabilities and potential of soft x-ray fluorescence spectroscopy for the study of the electronic\\u000a structure and chemical bonding of novel materials. The basic principle of x-ray fluorescence measurements using synchrotron\\u000a radiation and the corresponding instrumentation issues are outlined. Particular attention is given to x-ray spectroscopic\\u000a studies of the electronic structure and characterization of nanostructures, thin

E. Z. Kurmaev

2005-01-01

14

X-ray Spectroscopy of Cooling Cluster  

SciTech Connect

We review the X-ray spectra of the cores of clusters of galaxies. Recent high resolution X-ray spectroscopic observations have demonstrated a severe deficit of emission at the lowest X-ray temperatures as compared to that expected from simple radiative cooling models. The same observations have provided compelling evidence that the gas in the cores is cooling below half the maximum temperature. We review these results, discuss physical models of cooling clusters, and describe the X-ray instrumentation and analysis techniques used to make these observations. We discuss several viable mechanisms designed to cancel or distort the expected process of X-ray cluster cooling.

Peterson, J.R.; /SLAC; Fabian, A.C.; /Cambridge U., Inst. of Astron.

2006-01-17

15

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

NASA Technical Reports Server (NTRS)

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 this instrument is to provide a global monitor of electron energy input to the upper atmosphere. We describe the design, development, and calibration of AXIS and provide an assessment of its excellent on-orbit performance. The unique capabilities of X-ray imaging spectrometers are demonstrated through an analysis of specific examples from October and November 1991. Important new developments for follow-on instruments also will be described.

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

1992-01-01

16

X-ray spectroscopy of magnetic CVs  

NASA Astrophysics Data System (ADS)

I discuss two topics in X-ray spectroscopy of magnetic CVs: reflection from the white dwarf surface, and opacity effects in the post shock plasma. I also briefly mention future observational perspectives, with particular emphasis on the Constellation X-ray mission.

Matt, Giorgio

17

European XFEL: Soft X-Ray instrumentation  

SciTech Connect

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

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

2011-12-15

18

Instrumentation for X-ray Astronomy  

NASA Technical Reports Server (NTRS)

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

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

1994-01-01

19

Instrumentation for x-ray astronomy  

NASA Astrophysics Data System (ADS)

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

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

1993-01-01

20

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

PubMed

We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low power x-ray (bremsstrahlung) tube source, a spherically bent crystal analyzer, and an energy-resolving solid-state detector. This relatively inexpensive, introductory level instrument achieves 1-eV energy resolution for photon energies of ?5 keV to ?10 keV while also demonstrating a net efficiency previously seen only in laboratory monochromators having much coarser energy resolution. Despite the use of only a compact, air-cooled 10 W x-ray tube, we find count rates for nonresonant x-ray emission spectroscopy comparable to those achieved at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure, the monochromatized flux is small (due to the use of a low-powered x-ray generator) but still useful for routine transmission-mode studies of concentrated samples. These results indicate that upgrading to a standard commercial high-power line-focused x-ray tube or rotating anode x-ray generator would result in monochromatized fluxes of order 10(6)-10(7) photons/s with no loss in energy resolution. This work establishes core technical capabilities for a rejuvenation of laboratory-based hard x-ray spectroscopies that could have special relevance for contemporary research on catalytic or electrical energy storage systems using transition-metal, lanthanide, or noble-metal active species. PMID:25430123

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

21

In situ soft X-ray absorption spectroscopy of flames  

NASA Astrophysics Data System (ADS)

The feasibility of in situ soft X-ray absorption spectroscopy for imaging carbonaceous species in hydrocarbon flames is demonstrated using synchrotron radiation. Soft X-rays are absorbed by core level electrons in all carbon atoms regardless of their molecular structure. Core electron spectroscopy affords distinct advantages over valence spectroscopy, which forms the basis of traditional laser diagnostic techniques for combustion. In core level spectroscopy, the transition linewidths are predominantly determined by the instrument response function and the decay time of the core-hole, which is on the order of a femtosecond. As a result, soft X-ray absorption measurements can be performed in flames with negligible Doppler and collisional broadening. Core level spectroscopy has the further advantage of measuring all carbonaceous species regardless of molecular structure in the far-edge region, whereas near-edge features are molecule specific. Interferences from non-carbon flame species are unstructured and can be subtracted. In the present study, absorption measurements in the carbon K-edge region are demonstrated in low-pressure ( P total = 20-30 Torr) methane jet flames. Two-dimensional imaging of the major carbonaceous species, CH4, CO2, and CO, is accomplished by tuning the synchrotron radiation to the respective carbon K-edge, near-edge X-ray absorption fine structure (NEXAFS) transitions and scanning the burner.

Frank, Jonathan H.; Shavorskiy, Andrey; Bluhm, Hendrik; Coriton, Bruno; Huang, Erxiong; Osborn, David L.

2014-10-01

22

X-Ray spectroscopy of cooling flows  

NASA Technical Reports Server (NTRS)

Cooling flows in clusters of galaxies occur when the cooling time of the gas is shorter than the age of the cluster; material cools and falls to the center of the cluster potential. Evidence for short X-ray cooling times comes from imaging studies of clusters and X-ray spectroscopy of a few bright clusters. Because the mass accretion rate can be high (a few 100 solar mass units/year) the mass of material accumulated over the lifetime of a cluster can be as high as 10(exp 12) solar mass units. However, there is little evidence for this material at other wavelengths, and the final fate of the accretion material is unknown. X-ray spectra obtained with the Einstein SSS show evidence for absorption; if confirmed this result would imply that the accretion material is in the form of cool dense clouds. However ice on the SSS make these data difficult to interpret. We obtained ASCA spectra of the cooling flow cluster Abell 85. Our primary goals were to search for multi-temperature components that may be indicative of cool gas; search for temperature gradients across the cluster; and look for excess absorption in the cooling region.

Prestwich, Andrea

1996-01-01

23

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

24

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

25

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

PubMed

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

Sturhahn, W; Toellner, T S

2011-03-01

26

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

E-print Network

Quick extended x-ray absorption fine structure instrument with millisecond time scale, optimized 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

Sparks, Donald L.

27

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

28

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

29

A Laboratory-based Hard X-ray Monochromator for High-Resolution X-ray Emission Spectroscopy and X-ray Absorption Near Edge Structure Measurements  

E-print Network

We report the development of a laboratory-based Rowland-circle monochromator that incorporates a low poer x-ray (bremsstrahlung) tube source, a spherically-bent crystal analyzer (SBCA), 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 dmeonstrating 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 (XES) comparable to those achived at monochromatized spectroscopy beamlines at synchrotron light sources. For x-ray absorption near edge structure (XANES), 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-powered line-foc...

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

2014-01-01

30

X-ray ferromagnetic resonance spectroscopy  

SciTech Connect

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

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

2005-10-10

31

Spectroscopy in X-ray astronomy  

NASA Technical Reports Server (NTRS)

Detailed features in cosmic X-ray sources and their associated temporal variation over a wide energy range were studied. Excess emission and absorption at approximately 6 to 7 kiloelectron volts in the spectra of supernova remnants, binary X-ray sources, and clusters of galaxies were observed. A gas scintillation proportional counter (GSPC) will be used as the detector system. In the gas scintillator the principal limitation is due to the statistics of the initial ionization process only.

Andresen, R.

1981-01-01

32

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

33

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

34

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

35

X-ray spectroscopy of manganese clusters  

SciTech Connect

Much of this thesis represents the groundwork necessary in order to probe Mn clusters more productively than with conventional Mn K-edge XAS and is presented in Part 1. Part 2 contains the application of x-ray techniques to Mn metalloproteins and includes a prognosis at the end of each chapter. Individual Mn oxidation states are more readily distinguishable in Mn L-edge spectra. An empirical mixed valence simulation routine for determining the average Mn oxidation state has been developed. The first Mn L-edge spectra of a metalloprotein were measured and interpreted. The energy of Mn K{beta} emission is strongly correlated with average Mn oxidation state. K{beta} results support oxidation states of Mn(III){sub 2}(IV){sub 2} for the S{sub 1} state of Photosystem II chemical chemically reduced preparations contain predominantly Mn(II). A strength and limitation of XAS is that it probes all of the species of a particular element in a sample. It would often be advantageous to selectively probe different forms of the same element. The first demonstration that chemical shifts in x-ray fluorescence energies can be used to obtain oxidation state-selective x-ray absorption spectra is presented. Spin-dependent spectra can also be used to obtain a more simplified picture of local structure. The first spin-polarized extended x-ray absorption fine structure using Mn K{beta} fluorescence detection is shown.

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

1996-06-01

36

X-Ray Spectroscopy of Gold Nanoparticles  

NASA Astrophysics Data System (ADS)

Inner shell transitions, such as 1s-2p, in heavy elements can absorb or produce hard X-rays, and hence are widely used in nanoparticles. Bio-medical research for cancer treatment has been using heavy element nanoparticles, embeded in malignant tumor, for efficient absorption of irradiated X-rays and leading emission of hard X-rays and energetic electrons to kill the surrounding cells. Ejection of a 1s electron during ionization of the element by absorption of a X-ray photon initiates the Auger cascades of emission of photons and electrons. We have investigated gold nanoparticles for the optimal energy range, below the K-edge (1s) ionization threshold, that corresponds to resonant absorption of X-rays with large attenuation coefficients, orders of magnitude higher over the background as well as to that at K-edge threshold. We applied these attenuation coefficients in Monte Carlo simulation to study the intensities of emission of photons and electrons by Auger cascades. The numerical experiments were carried out in a phantom of water cube with a thin layer, 0.1mm/g, of gold nanoparticles 10 cm inside from the surface using the well-known code Geant4. We will present results on photon and electron emission spectra from passing monochromatic X-ray beams at 67 keV, which is the resonant energy for resonant K_{?} lines, at 82 keV, the K-shell ionization threshold, and at 2 MeV where the resonant effect is non-existent. Our findings show a high peak in the gold nanoparticle absorption curve indicating complete absorption of radiation within the gold layer. The photon and electron emission spectra show resonant features. Acknowledgement: Partially supported by a Large Interdisciplinary Grant award of the Ohio State University and NASA APRA program (SNN). The computational work was carried out on the Cray X1 and Itanium 4 cluster at the Ohio Supercomputer Center, Columbus Ohio. "Resonant X-ray Irradiation of High-Z Nanoparticles For Cancer Theranostics" (refereed presentation), A Pradhan, S Nahar, M Montenegro, C Sur, M Mrozik, R Pitzer, E Silver, Y Yu, 50th Annual Meeting of the American Association of Physicists in Medicine in Houston, Texas, July 27 - 31, 2008

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

2009-06-01

37

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

38

X-Ray Photoelectron Spectroscopy on Magnetic Metals  

Microsoft Academic Search

Photoelectron spectroscopy offers one of the most direct methods for observing the density-of-states function N(E) in metals. We have used x-ray photoelectron spectroscopy (XPS) to study N(E) for the valence bands of Fe, Co, Ni, Cu, and Pt. X rays offer the advantage over lower-energy photons that the directly observable kinetic energy spectrum is probably more closely related to N(E).

C. S. Fadley; D. A. Shirley

1969-01-01

39

Synchrotron radiation, soft-X-ray spectroscopy andnanomaterials  

SciTech Connect

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

Guo, Jinghua

2004-09-13

40

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

41

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

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

42

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

43

Temperature dependent soft x-ray absorption spectroscopy of liquids.  

PubMed

A novel sample holder is introduced which allows for temperature dependent soft x-ray absorption spectroscopy of liquids in transmission mode. The setup is based on sample cells with x-ray transmissive silicon nitride windows. A cooling circuit allows for temperature regulation of the sample liquid between -10?°C and +50?°C. The setup enables to record soft x-ray absorption spectra of liquids in transmission mode with a temperature resolution of 0.5?K and better. Reliability and reproducibility of the spectra are demonstrated by investigating the characteristic temperature-induced changes in the oxygen K-edge x-ray absorption spectrum of liquid water. These are compared to the corresponding changes in the oxygen K-edge spectra from x-ray Raman scattering. PMID:25362366

Meibohm, Jan; Schreck, Simon; Wernet, Philippe

2014-10-01

44

Temperature dependent soft x-ray absorption spectroscopy of liquids  

NASA Astrophysics Data System (ADS)

A novel sample holder is introduced which allows for temperature dependent soft x-ray absorption spectroscopy of liquids in transmission mode. The setup is based on sample cells with x-ray transmissive silicon nitride windows. A cooling circuit allows for temperature regulation of the sample liquid between -10 °C and +50 °C. The setup enables to record soft x-ray absorption spectra of liquids in transmission mode with a temperature resolution of 0.5 K and better. Reliability and reproducibility of the spectra are demonstrated by investigating the characteristic temperature-induced changes in the oxygen K-edge x-ray absorption spectrum of liquid water. These are compared to the corresponding changes in the oxygen K-edge spectra from x-ray Raman scattering.

Meibohm, Jan; Schreck, Simon; Wernet, Philippe

2014-10-01

45

Hazards in the use of x-ray analytical instrumentation  

Microsoft Academic Search

This paper outlines the potential hazards in the use of X-ray analytical instrumentation and is composed of two major sections. The first section defines the terminology employed and outlines the causes and effects of radiation damage. Also covered is the national recognition of the problem which has led to present day legislation of dose levels. The second part is a

R. Jenkins; D. J. Haas

1973-01-01

46

Advanced X-ray Astrophysics Facility (AXAF) science instrumentation  

NASA Technical Reports Server (NTRS)

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

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

1985-01-01

47

X-Ray Spectroscopy Using Low Temperature Detectors  

NASA Technical Reports Server (NTRS)

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

Porter, Frederick

2011-01-01

48

Small pixel CZT detector for hard X-ray spectroscopy  

Microsoft Academic Search

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

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

2011-01-01

49

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

SciTech Connect

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

Tobin, J G

2011-03-17

50

Measuring 10 fs dynamics via resonant x-ray pump/x-ray probe spectroscopy  

NASA Astrophysics Data System (ADS)

We used two x-ray pulses to investigate the femtosecond scale molecular response to K-shell resonant excitation in O2. Our results give three perspectives on this dynamic response: 1) sub-10 fs transient bleaching of resonant absorption, 2) a corresponding sub-10 fs evolution of the resonant Auger electron spectrum, and 3) a 10--15 fs evolution of electronic molecular symmetry. The x-ray pulses are tuned to the 531 eV 1s->2p&*circ; resonance in O2. Upon excitation by the first pulse, further absorption is suppressed until the dynamic molecular valence pulls a new valence state into resonance. The new resonance occurs only after about 5--10 fs and reveals opposite electronic symmetry to the ?*. After 15 fs, this newly resonant state has lost molecular symmetry and undergoes atomic-like resonant absorption. We have thus used x-ray pump-probe spectroscopy to build a time-domain picture of the ˜10 fs molecular response to x-ray absorption.

Coffee, Ryan; Bionta, Mina; Hartmann, Nick; Cryan, James; Glownia, James; Natan, Adi; French, Doug; Siano, Marco

2012-06-01

51

Detection of electromagnetic multipoles by x-ray spectroscopies  

NASA Astrophysics Data System (ADS)

Following a brief discussion on electromagnetic multipole expansion, we provide a link between several multipole moments and the measurable quantities of some x-ray spectroscopies, like resonant x-ray scattering or dichroism in absorption. A general classification is given, accompanied by some specific examples and a geometrical interpretation of the axial toroidal (nonmagnetic) quadrupole, related to the x-ray natural circular dichroism. Finally, in order to provide a physical example for the detection of magnetic parity-odd multipoles, like the toroidal moment, we perform a numerical simulation for x-ray nonreciprocal directional dichroism, at the Fe K edge, in the polar ferrimagnet GaFeO3 . Our calculations describe quite well the reported experimental profile, with the correct order of magnitude for dichroism/absorption intensity ratio and a signal which is limited to pre-edge.

di Matteo, S.; Joly, Y.; Natoli, C. R.

2005-10-01

52

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

53

Advanced X-ray Astrophysics Facility (AXAF) instrumentation  

NASA Technical Reports Server (NTRS)

The instrumentation planned for the Advanced X-ray Astrophysics Facility (AXAF), a space-based observation platform for the 1990s, is described. The AXAF will feature a grazing incidence telescope at the end of the observatory and four independently selected instruments at the other end, including: a CCD imaging spectrometer; a Bragg crystal spectrometer; and two transmission grating spectrometers located directly behind the telescope to detect first order spectral images. The instruments are currently in the definition phase to be followed by design and development starting in the late 1980s. A detailed schematic diagram of the Bragg crystal imaging spectrometer is provided.

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

1986-01-01

54

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

NASA Astrophysics Data System (ADS)

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

Katayama, Tetsuo; Inubushi, Yuichi; Obara, Yuki; Sato, Takahiro; Togashi, Tadashi; Tono, Kensuke; Hatsui, Takaki; Kameshima, Takashi; Bhattacharya, Atanu; Ogi, Yoshihiro; Kurahashi, Naoya; Misawa, Kazuhiko; Suzuki, Toshinori; Yabashi, Makina

2013-09-01

55

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

56

[Development of Nanotechnology for X-Ray Astronomy Instrumentation  

NASA Technical Reports Server (NTRS)

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

Schattenburg, Mark L.

2004-01-01

57

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

58

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

59

X-ray- and electron induced infrared emission spectroscopy.  

SciTech Connect

We demonstrate the use of Fourier transform infrared (IR) spectroscopy for midinfrared emission measurements following x-ray or electron excitation. Spectra from an InAs low band-gap semiconductor film, which emits in the IR from 3000 to 3400 cm{sup -1}, are presented. There is good agreement between the present results and previously published laser-excited spectra. Using focused beams, it should be possible to perform sub-diffraction-limited IR imaging. In addition, simultaneous structural and electronic analysis could be performed using the x-ray or electron excitation probes.

Rosenberg, R. A.; Abu Haija, M.; Watkins, S. P. (X-Ray Science Division); (Simon Fraser Univ.)

2009-04-01

60

X-ray- and electron-induced infrared emission spectroscopy.  

PubMed

We demonstrate the use of Fourier transform infrared (IR) spectroscopy for midinfrared emission measurements following x-ray or electron excitation. Spectra from an InAs low band-gap semiconductor film, which emits in the IR from 3000 to 3400 cm(-1), are presented. There is good agreement between the present results and previously published laser-excited spectra. Using focused beams, it should be possible to perform sub-diffraction-limited IR imaging. In addition, simultaneous structural and electronic analysis could be performed using the x-ray or electron excitation probes. PMID:19405700

Rosenberg, R A; Abu Haija, M; Watkins, S P

2009-04-01

61

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

62

A rocket borne instrument for the study of soft X-ray emission from cosmic X-ray sources  

NASA Technical Reports Server (NTRS)

Details about a rocket-borne instrument designed for studying the various characteristics of soft X-ray emission from cosmic X-ray sources in the energy range of 0.2 to 3 keV are presented. The X-ray detector consists of a bank of four multilayer, wall-less proportional counters, each with an area of 400 sq cm. The detectors are covered by windows of 1.4-micron polypropylene and are maintained at a constant pressure in flight using a gas control system. Two of the detectors are equipped with 0.4- by 10-deg collimators for mapping the spatial distribution of soft X-rays from extended X-ray sources. A pair of balanced filters consisting of oxygen and CF4 are used for detecting oxygen emission lines.

Agrawal, P. C.; Moore, W. E.; Garmire, G. P.

1974-01-01

63

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

64

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

65

High-resolution X-ray spectroscopy of Theta Car  

E-print Network

Context : The peculiar hot star Theta Car in the open cluster IC2602 is a blue straggler as well as a single-line binary of 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 50ks 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--6MK) 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 beta Cru and tau 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 (solar-like?). While no significant changes occur during the XMM-Newton observation, variability in the X-ray domain is detected on the long-term range. The formation radius of the X-ray emission is loosely constrained to <5 R_sol, 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.

Yael Naze; Gregor Rauw

2008-08-25

66

Calibration Method Using a Solar X-Ray Monitor with a Standard Sample for Planetary Remote X-Ray Spectroscopy  

NASA Astrophysics Data System (ADS)

Planetary remote XRF spectroscopy should provide major elemental composition as precisely as possible. Uncertainty of solar X-ray monitoring is a crucial topic on this, and we propose onboard calibration method with a standard sample.

Okada, T.

2011-03-01

67

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

E-print Network

In this thesis, I present work spanning a variety of topics relating to neutron star lowmass X-ray binaries (LMXBs) and utilize spectral information from X-ray observations to further our understanding of these sources. ...

Krauss, Miriam Ilana

2007-01-01

68

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

2014-01-31

69

X-ray absorption spectroscopy: EXAFS (Extended X-ray Absorption Fine Structure) and XANES (X-ray Absorption Near Edge Structure)  

Microsoft Academic Search

The x-ray absorption spectroscopy (XAS) had been an essential tool to gather spectroscopic information about atomic energy level structure in the early decades of this century. It has also played an important role in the discovery and systematization of rare-earth elements. The discovery of synchrotron radiation in 1952, and later the availability of broadly tunable synchrotron based x-ray sources have

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

1990-01-01

70

Probing deeper by hard x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

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.; Martinez, E.; Detlefs, B.; Delaye, V.; Zegenhagen, J.; Gaumer, C.; Grenet, G.; Tougaard, S.

2014-02-01

71

Pushing the Boundaries of Suborbital Soft X-ray Spectroscopy  

NASA Astrophysics Data System (ADS)

There are two primary objectives for this investigation. First, we propose to launch a preexisting payload to perform scientific investigations. Second, we propose to build a new payload which will integrate and demonstrate key technologies vital to future X-ray observatories. These efforts will train graduate students and prepare junior researchers to be major contributors to the next suite of NASA missions. We propose to increase the ability of gratings to obtain high resolution at energies below 1 keV. The concept that will be developed in this proposed investigation will be capable of meeting the requirements of future X-ray observatories. In addition, the design could be utilized effectively on smaller, Explorer class missions as pathfinders to the larger observatories while providing important scientific insights along the way. For this investigation, we propose to fly two separate, but related, rocket payloads. The first payload, christened OGRESS, has already been constructed and successfully flown three times. OGRESS is optimized to observe diffuse X-ray sources with a wire-grid collimating optic, parallel groove sinusoidal gratings, and Gaseous Electron Multiplier (GEM) detectors and is capable of attaining high resolution of E/dE ~ 25-80 in the 1/4 keV band. OGRESS will take high resolution spectra of the Vela Supernova Remnant (SNR) in the 1/4 keV band. This flight will provide the highest resolution spectra yet taken of Vela in this band and will produce a PhD thesis. The second payload, OGRE, will demonstrate key technologies necessary for the next X-ray observatory and provide even higher resolution of E/dE ~ 1000-2000 between 0.2 1.0 keV. To improve upon the resolution of OGRESS, OGRE will integrate several key technologies which have already been developed in a laboratory setting, but have not been flight proven. OGRE will use a modified Wolter telescope made from slumped glass to provide a smaller focus and increase throughput. Slumped glass optics are planned for every future large X-ray mission and flight-proving the design is extremely important. The gratings will be radially grooved and blazed to reduce grating aberrations and to focus the spectrum to one side of zero-order. Gratings of this type have been well developed by the IXO Off- Plane X-ray Grating Spectrometer concept study, but have not been flight proven. The spectrum will be focused onto high spatial resolution CCD detectors. OGRE will draw heavily from the heritage gained from OGRESS. OGRE will observe Capella. Due to its high flux and spectral line density, Capella is an ideal target for showcasing the resolution capabilities of our instrument. As an important calibration target, our improved resolution measurements will be extremely helpful for many future X-ray observations. OGRESS has already provided three thesis projects for past graduate students. The upgrades and flights proposed here will produce at least two more PhD theses. This program in hands-on training of young scientists in the techniques of instrumental X-ray astronomy has proven very successful over nearly three decades, leading to high rates of launch, publication, graduation, and flight qualification of instrumental PI's. It will also provide full experiment cycle experience - design, fabrication, tolerancing, assembly, flight-qualification, calibration, integration, launch, and data analysis - with reflection gratings, GEM and CCD detectors, and other technologies suitable for adaptation to NASA's major missions. The University of Iowa and University of Colorado programs in suborbital X-ray astronomy represent an exciting mix of compelling science, cutting- edge technology development, and training of young scientists.

McEntaffer, Randall

72

Characterization of ferroelectric ceramics using x-ray diffraction, transmission electron microscopy, and x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Ferroelectric ceramic samples of PbTiO3, prepared by a modified oxide-mixing technique, were examined by x-ray diffraction (XRD) and transmission electron microscopy (TEM) techniques for crystalline and microstructural characterization. XRD clearly revealed only a monophasic perovskite of tetragonal symmetry for the reference PbTiO3, which was established to possess both a-a-and a-c-type 90° domains. The inclination was approximately 2° between the two different domains, as observed by high-resolution TEM. Inductively coupled plasma (ICP) analysis, electron probe microanalysis (EPMA), and x-ray photoelectron spectroscopy (XPS) were employed and the ensuing chemical composition results are discussed. The approximate molar ratios of Pb:Ti were 1:1, 1:1.5, and 1:0.8 as obtained by ICP analysis, EPMA, and XPS, respectively. Corrections for the sensitivity factor (SCorr) for Pb 4f, Ti 2p and the substitution of the matrix factors for FTi,Pb, FPb,Ti have been taken into account in obtaining the Pb:Ti ratio of 1:1 by XPS quantification. The sensitivity factor (SKratos) given by the instrumental maker was compared with the theoretical one (STheo) and the result is also discussed.

Kim, Jae-Nam; Shin, Kwang-Soo; Park, Byung-Ok; Lee, Jin-Hong; Kim, Nam-Kyoung; Cho, Sang-Hee

2003-08-01

73

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

74

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

NASA Astrophysics Data System (ADS)

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

Kahn, S. M.

2002-12-01

75

X-ray absorption spectroscopy of liquid surfaces  

NASA Astrophysics Data System (ADS)

By combining synchrotron-based x-ray spectroscopy with liquid microjets, we have developed new techniques for the investigation of the geometric and electronic structure of volatile liquid surfaces. An endstation has been constructed to allow windowless introduction of volatile liquids to the UHV environment of synchrotron soft x-ray beamlines (Advanced Light Source, LBL). The high vacuum (10-5 torr) obtained in the photon-microjet interaction volume, allows the use of standard surface science charged particle detection to analyze the ions and electrons produced via core-level excitation. The difference in escape depths of ions and electrons from condensed phase samples yields convenient surface-bulk contrast via the total ion (TIY) (˜5 A) versus the total electron (TEY) (˜20--50 A) yields. This contrast has been exploited in an effort to understand the surface hydrogen bond structure of liquid water and methanol. The temperature profile of these microjets has been characterized under the high vacuum conditions essential for measuring x-ray absorption "action" spectra. We find only moderate cooling of larger diameter (>10 microns) microjets, while smaller jets undergo rapid evaporation, yielding liquid water temperatures as low as -36°C. Extended x-ray absorption fine structure (EXAFS) is a common technique that is an ideal probe of local "liquid structure" (near neighbor distance, coordination numbers, etc.). Moreover, the EXAFS TIY and TEY "action" spectra allow the direct comparison of surface and bulk liquid properties. In both liquid water and methanol, a sizable surface relaxation of the intermolecular O-O distance is observed. On average water molecules at the liquid surface are ˜6% further apart than their bulk counterparts. Near edge x-ray absorption fine structure (NEXAFS) has been shown to be extremely sensitive to not only to the formation of hydrogen bonds, but more importantly to the detailed nature (acceptor vs. donor) of such bonds. TIY NEXAFS spectra combined with DFT analysis has yielded evidence for at least two different species at the liquid water surface. The sharp spectral structure in the TIY signal provides a clear fingerprint for "acceptor-only" H2O molecules at the liquid water interface. Analysis of mass-selected NEXAFS spectra provide corroborating evidence for surface single donor molecules that have been previously identified by SFG spectroscopy. (Abstract shortened by UMI.)

Wilson, Kevin Roger

76

Raman chirped adiabatic passage probed by X-ray spectroscopy.  

PubMed

We report a theoretical study of the selective vibrational excitation of a HCl molecule achieved by Raman chirped adiabatic passage (RCAP) and probed by X-ray photoelectron spectroscopy (XPS). It is demonstrated that HCl can be prepared in any vibrational level up to ? = 9 with nearly complete population inversion. We explore the effects of both the rotation of the molecule and of the temperature on the RCAP process, which is proved to be very robust. Furthermore, we emphasize that XPS spectra at the chlorine K-shell threshold show characteristic signatures of the populated vibrational level, allowing us to follow the RCAP process. PMID:23550700

Engin, Selma; Sisourat, Nicolas; Selles, Patricia; Taïeb, Richard; Carniato, Stéphane

2013-08-29

77

X-Ray Absorption Spectroscopy of Uranium Dioxide  

SciTech Connect

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

Tobin, J G

2010-12-10

78

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

PubMed Central

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

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

2012-01-01

79

Hubbard Model Approach to X-ray Spectroscopy  

NASA Astrophysics Data System (ADS)

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

Ahmed, Towfiq

80

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

81

X-ray instrumentation in astronomy; Proceedings of the Meeting, Cannes, France, December 2-4, 1985  

NASA Technical Reports Server (NTRS)

Recent developments in X-ray and EUV astronomical instrumentation are discussed in reviews and reports. Topics examined include optical systems for the NASA Advanced X-ray Astrophysics Facility (AXAF), specialized X-ray systems, advanced X-ray optics, gas-filled X-ray detectors, instrumentation for spectrometry on AXAF, X-ray and EUV spectrometers, microchannel plate detectors, and solid-state detectors.

Culhane, J. L. (editor)

1986-01-01

82

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

NASA Technical Reports Server (NTRS)

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

Gorenstein, P.

1984-01-01

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

CUBIC - A non-dispersive Diffuse X-ray Background spectrometer. [Cosmic Unresolved X-ray Background Instrument  

NASA Technical Reports Server (NTRS)

The Cosmic Unresolved X-ray Background Instrument using CCDs (CUBIC) is designed to obtain spectral observations of the Diffuse X-ray Background (DXRB) with moderate spectral resolution over the energy range 0.2-10 keV, using mechanically-collimated CCDs. At this time, it is the only planned satellite payload devoted to the study of the spectrum of the DXRB. Over the anticipated 3 year lifetime of the satellite, CUBIC will be able to study up to 50 percent of the sky with 5 x 5 deg spatial resolution for the subkilovolt Galactic diffuse background, and with 10 x 10 deg spatial resolution for the extragalactic diffuse background above 2 keV. CUBIC will obtain high quality nondispersive spectra of soft X-ray emission from the interstellar medium, supernova remnants, and some bright sources, and will make a sensitive seach for line emission or other features in the extragalactic cosmic X-ray background from 2-10 keV.

Burrows, David N.; Skinner, Mark A.; Antunes, Alexander J. D.; Catalano, Mark A.; Cocklin, Eric J.; Engel, Leland G.; Entingh, Timothy J.; Garmire, Gordon P.; Green, Roland; Kelly, Douglas A.

1992-01-01

85

X-ray Spectroscopy of O Supergiant Winds: Shock Physics, Clumping, and Mass-Loss Rates  

E-print Network

X-ray Spectroscopy of O Supergiant Winds: Shock Physics, Clumping, and Mass-Loss Rates David Cohen-ray emission: wind shocks 1. X-ray constraints on the shocked wind plasma 2. X-ray absorption as a mass. Adiabatic shocks Open questions: very dense winds (WR stars); low density winds (B stars); magnetic OB stars

Cohen, David

86

In Situ Diffuse Reflectance IR Spectroscopy and X-ray Absorption Spectroscopy for Fast Catalytic Processes  

SciTech Connect

A new instrument for synchronous in situ investigations of catalytic materials by IR and X-ray absorption spectroscopies was designed and built at the X18A beamline of the National Synchrotron Light Source of Brookhaven National Laboratory. It provides analytical tools for solving structural, electronic and kinetic problems in catalysis science by two complementary methods. Among the features attractive for catalysis research are the broad range of catalytically active elements that can be investigated (starting with Ni and beyond), the wide range of reaction conditions (temperatures up to 873 K, various reactive gases) and time scales (starting from tens of seconds). The results of several representative experiments that illustrate the attractive capabilities of the new set-up are discussed.

N Marinkovic; Q Wang; A Frenkel

2011-12-31

87

Time-resolved x-ray photoelectron spectroscopy at FLASH  

NASA Astrophysics Data System (ADS)

The technique of time-resolved pump-probe x-ray photoelectron spectroscopy using the free-electron laser in Hamburg (FLASH) is described in detail. Particular foci lie on the macrobunch resolving detection scheme, the role of vacuum space-charge effects and the synchronization of pump and probe lasers. In an exemplary case study, the complete Ta 4f core-level dynamics in the layered charge-density-wave (CDW) compound 1T-TaS2 in response to impulsive optical excitation is measured on the sub-picosecond to nanosecond timescale. The observed multi-component dynamics is related to the intrinsic melting and reformation of the CDW as well as to extrinsic pump-laser-induced vacuum space-charge effects.

Hellmann, S.; Sohrt, C.; Beye, M.; Rohwer, T.; Sorgenfrei, F.; Marczynski-Bühlow, M.; Kalläne, M.; Redlin, H.; Hennies, F.; Bauer, M.; Föhlisch, A.; Kipp, L.; Wurth, W.; Rossnagel, K.

2012-01-01

88

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

89

heterojunction interface investigated by X-ray photoemission spectroscopy  

NASA Astrophysics Data System (ADS)

The band alignment at the In2S3/Cu2ZnSnS4 heterojunction interface is investigated by X-ray photoemission spectroscopy. In2S3 is thermally evaporated onto the contamination-free polycrystalline Cu2ZnSnS4 surface prepared by magnetron sputtering. The valence band offset is measured to be 0.46 ± 0.1 eV, which matches well with the valance band offset value 0.49 eV calculated using "transitivity" method. The conduction band offset is determined to be 0.82 ± 0.1 eV, indicating a `type I' band alignment at the heterojunction interface.

Lin, Lingyan; Yu, Jinling; Cheng, Shuying; Lu, Peimin; Lai, Yunfeng; Lin, Sile; Zhao, Pengyi

2014-09-01

90

The Constellation-X Spectroscopy X-Ray Telescope  

NASA Technical Reports Server (NTRS)

The status of technology development for the Constellation-X Spectroscopy X-ray Telescope (SXT) mirror is presented. The SXT mirror combines a large (1.6 m) aperture with modest (12 arc sec half power diameter) angular resolution and low mass (750 kg). The overall collecting area, larger than 9,600 square cm at 0.25 keV, requires high throughput, and thus nesting of a substantial number of thin reflectors. A phased development program is underway to develop reflectors, mounting and alignment approaches, and metrology techniques for components and the mirror has a whole. The latest results in all these areas are summarized, along with an overview of results of optical testing of reflector performance.

Petre, Robert; Content, David; Lehan, John; O'Dell, Stephen; Owens, Scott; Podgorsky, William; Stewart, Jeff; Zhang, William

2004-01-01

91

The LNLS soft X-ray spectroscopy beamline.  

PubMed

The soft X-ray spectroscopy beamline installed at a bending-magnet source at the LNLS is described. The optics are designed to cover energies from 800 to 4000 eV with good efficiency. The focusing element is a gold-coated toroidal mirror with an angle of incidence of 17 mrad. The UHV double-crystal monochromator has three pairs of crystals, Si (111), InSb (111) and beryl (101;0), that can be selected by a sliding movement. The UHV workstation is equipped with an ion gun, an electron gun, an electron analyser, LEED optics, an open channeltron and a photodiode array. This beamline is intended for photoemission, photoabsorption, reflectivity and dichroism experiments. PMID:15263571

Tolentino, H; Compagnon-Cailhol, V; Vicentin, F C; Abbate, M

1998-05-01

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

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

94

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

95

Multiangular regolith effects on planetary soft X-ray fluorescence spectroscopy  

Microsoft Academic Search

Fluorescent X-rays from the surfaces of airless planetary bodies in the inner solar system have been measured by instruments on several spacecraft. 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

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

2009-01-01

96

Determination of the phase composition of surface layers of porous silicon by ultrasoft X-ray spectroscopy and X-ray photoelectron spectroscopy techniques  

Microsoft Academic Search

The phase composition of the surface layers in porous silicon (por-Si) is determined by analysis of the density of states in the valence band using ultrasoft X-ray emission spectroscopy (USXES) and X-ray photoelectron spectroscopy (XPS) of the core levels. Since porous silicon demonstrates instability of its properties the investigations of the changes in its phase composition under atmosphere exposure (e.g.

V. A Terekhov; V. M Kashkarov; E. Yu. Manukovskii; A. V Schukarev; E. P Domashevskaya

2001-01-01

97

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

98

Electron Spectroscopy: Ultraviolet and X-Ray Excitation.  

ERIC Educational Resources Information Center

Reviews recent growth in electron spectroscopy (54 papers cited). Emphasizes advances in instrumentation and interpretation (52); photoionization, cross-sections and angular distributions (22); studies of atoms and small molecules (35); transition, lanthanide and actinide metal complexes (50); organometallic (12) and inorganic compounds (2);…

Baker, A. D.; And Others

1980-01-01

99

Surface characterization of amalgams using X-ray photoelectron spectroscopy.  

PubMed

This study is the first to report on the use of x-ray photoelectron spectroscopy (XPS or ESCA) for studying the surface films (less than 10 nm thick) of aged amalgams. The concentrations and electron binding energies of the elements on the surfaces of four different amalgams aged for 20 min, one day, seven days, and 30 days were determined quantitatively. For comparison, the bulk compositions of the amalgams aged for seven days were also determined after removal of approximately 5 nm of material from the surface by argon-ion-sputtering. The XPS data revealed that the surface films of aged zinc-containing amalgams were not a simple oxide but were primarily composed of a (hydrated) tin and zinc oxy-hydroxide, whereas, in the zinc-free amalgams, the surface films were primarily a tin oxide. The concentration of mercury in this thin surface film after aging was depleted. This suggests that tin and/or zinc preferentially diffused to the surface and combined with oxygen, forming a surface film and diluting the mercury concentration in the surface. Another probable explanation for the depleted mercury is that a minimal amount of mercury in the surface film evaporated during the aging. PMID:3476619

Hanawa, T; Takahashi, H; Ota, M; Pinizzotto, R F; Ferracane, J L; Okabe, T

1987-09-01

100

Diffraction peaks in x ray spectroscopy: Friend or foe?  

NASA Astrophysics Data System (ADS)

Diffraction peaks can occur as unidentifiable peaks in the energy spectrum of an x-ray spectrometric analysis. Recently, there has been increased interest in oriented polycrystalline films and epitaxial films on single crystal substrates for electronic applications. Since these materials diffract x-rays more efficiently than randomly oriented polycrystalline materials, diffraction peaks are being observed more frequently in x-ray fluorescent spectra. In addition, micro x-ray spectrometric analysis utilizes a small, intense, collimated x-ray beam that can yield well defined diffraction peaks. In some cases these diffraction peaks can occur at the same position as elemental peaks. These diffraction peaks, although a possible problem in qualitative and quantitative elemental analysis, can give very useful information about the crystallographic structure and orientation of the material being analyzed. The observed diffraction peaks are dependent on the geometry of the x-ray spectrometer, the degree of collimation, and the distribution of wavelengths (energies) originating from the x-ray tube and striking the sample.

Tissot, R. G.; Goehner, R. P.

101

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

PubMed

A new liquid microjet endstation designed for ultraviolet (UPS) and X-ray (XPS) photoelectron, and partial electron yield X-ray absorption (XAS) spectroscopies at the Swiss Light Source is presented. The new endstation, which is based on a Scienta HiPP-2 R4000 electron spectrometer, is the first liquid microjet endstation capable of operating in vacuum and in ambient pressures up to the equilibrium vapor pressure of liquid water at room temperature. In addition, the Scienta HiPP-2 R4000 energy analyzer of this new endstation allows for XPS measurements up to 7000 eV electron kinetic energy that will enable electronic structure measurements of bulk solutions and buried interfaces from liquid microjet samples. The endstation is designed to operate at the soft X-ray SIM beamline and at the tender X-ray Phoenix beamline. The endstation can also be operated using a Scienta 5 K ultraviolet helium lamp for dedicated UPS measurements at the vapor-liquid interface using either He I or He II ? lines. The design concept, first results from UPS, soft X-ray XPS, and partial electron yield XAS measurements, and an outlook to the potential of this endstation are presented. PMID:23902081

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

2013-07-01

102

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

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

103

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

SciTech Connect

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

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

2013-07-15

104

X-ray spectroscopy of five BL Lacertae objects  

NASA Technical Reports Server (NTRS)

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

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

1986-01-01

105

Development of spatially resolved high resolution x-ray spectroscopy for fusion and light-source research  

NASA Astrophysics Data System (ADS)

One dimensional spatially resolved high resolution x-ray spectroscopy with spherically bent crystals and 2D pixelated detectors is an established technique on magnetic confinement fusion (MCF) experiments world wide for Doppler measurements of spatial profiles of plasma ion temperature and flow velocity. This technique is being further developed for diagnosis of High Energy Density Physics (HEDP) plasmas at laser-plasma facilities and synchrotron/x-ray free electron laser (XFEL) facilities. Useful spatial resolution (micron scale) of such small-scale plasma sources requires magnification, because of the finite pixel size of x-ray CCD detectors (13.5 ?m). A von-Hamos like spectrometer using spherical crystals is capable of magnification, as well as uniform sagittal focusing across the full x-ray spectrum, and is being tested in laboratory experiments using a tungsten-target microfocus (5-10 ?m) x-ray tube and 13-?m pixel x-ray CCD. A spatial resolution better than 10 ?m has been demonstrated. Good spectral resolution is indicated by small differences (0.02 - 0.1 eV) of measured line widths with best available published natural line widths. Progress and status of HEDP measurements and the physics basis for these diagnostics are presented. A new type of x-ray crystal spectrometer with a convex spherically bent crystal is also reported. The status of testing of a 2D imaging microscope using matched pairs of spherical crystals with x rays will also be presented. The use of computational x-ray optics codes in development of these instrumental concepts is addressed.

Lu, J.; Hill, K. W.; Bitter, M.; Delgado-Aparicio, L.; Pablant, N. A.; Efthimion, P.; Beiersdorfer, P.; Chen, H.; Widmann, K.; Sanchez del Rio, M.

2014-09-01

106

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

SciTech Connect

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

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

2006-02-01

107

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

108

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

PubMed

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. PMID:20590225

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

2010-06-01

109

First-principles X-ray Photoelectron Spectroscopy Calculation on Defects in Semiconductors  

E-print Network

Energylevel Photoelectron spectra h h valence band core level h I(E) Figure 1: Schematic diagram of XFirst-principles X-ray Photoelectron Spectroscopy Calculation on Defects in Semiconductors Jun Ltd., Hatoyama, Saitama 350-0395 Abstract We outline a first-principles core-level X-ray photoelectron

Katsumoto, Shingo

110

Advancements in Time-Resolved X-Ray Laser Induced Time-of-Flight Photoelectron Spectroscopy.  

National Technical Information Service (NTIS)

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-...

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

2005-01-01

111

Probing electronic structure and chemical bonding with x-ray spectroscopy  

Microsoft Academic Search

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

Astrid Jurgensen

1999-01-01

112

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

113

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

NASA Astrophysics Data System (ADS)

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&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, BaF2 and PbWO4, 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

2013-04-01

114

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

115

An instrument for combining x-ray multiple diffraction and x-ray topographic imaging for examining crystal microcrystallography and perfection  

SciTech Connect

Diffraction imaging using x-ray topography (XRT) and x-ray multiple diffraction (XRMD) provide valuable tools for examining the growth defects in crystals and the distributions from ideal lattice symmetry (microcrystallography). The topographic x-ray multiple diffraction microprobe (TMDM) combines the complementary aspects of both techniques enabling XRT and XRMD studies within the same instrument providing a useful resource for the structural characterization of materials that are not very stable in vacuum and electron beam environments. The design of the TMDM instrument is described together with data taken on GaAs (001) and potassium dihydrogen phosphate (001)

Lai, X.; Ma, C. Y.; Roberts, K. J. [Institute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); Cardoso, L. P. [Institute of Particle Science and Engineering, School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT (United Kingdom); IFGW, UNICAMP, CP 6165, 13083-970 Campinas, SP (Brazil); Santos, A. O. dos [IFGW, UNICAMP, CP 6165, 13083-970 Campinas, SP (Brazil); Bogg, D.; Miller, M. C. [STFC Daresbury Laboratory, Warrington WA4 4AD (United Kingdom)

2009-03-15

116

The soft x-ray instrument for materials studies at the linac coherent light source x-ray free-electron laser  

NASA Astrophysics Data System (ADS)

The soft x-ray materials science instrument is the second operational beamline at the linac coherent light source x-ray free electron laser. The instrument operates with a photon energy range of 480-2000 eV and features a grating monochromator as well as bendable refocusing mirrors. A broad range of experimental stations may be installed to study diverse scientific topics such as: ultrafast chemistry, surface science, highly correlated electron systems, matter under extreme conditions, and laboratory astrophysics. Preliminary commissioning results are presented including the first soft x-ray single-shot energy spectrum from a free electron laser.

Schlotter, W. F.; Turner, J. J.; Rowen, M.; Heimann, P.; Holmes, M.; Krupin, O.; Messerschmidt, M.; Moeller, S.; Krzywinski, J.; Soufli, R.; Fernández-Perea, M.; Kelez, N.; Lee, S.; Coffee, R.; Hays, G.; Beye, M.; Gerken, N.; Sorgenfrei, F.; Hau-Riege, S.; Juha, L.; Chalupsky, J.; Hajkova, V.; Mancuso, A. P.; Singer, A.; Yefanov, O.; Vartanyants, I. A.; Cadenazzi, G.; Abbey, B.; Nugent, K. A.; Sinn, H.; Lüning, J.; Schaffert, S.; Eisebitt, S.; Lee, W.-S.; Scherz, A.; Nilsson, A. R.; Wurth, W.

2012-04-01

117

On line shape analysis in X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Any solid state X-ray photoelectron spectrum (XPS) contains contributions due to multiple inelastic scattering in the bulk, surface excitations, energy losses originating from the screening of the final state hole (intrinsic losses), and, for non-monochromatized incident radiation, ghost lines originating from the X-ray satellites. In the present paper it is shown how all these contributions can be consecutively removed from an experimental spectrum employing a single general deconvolution procedure. Application of this method is possible whenever the contributions mentioned above are uncorrelated. It is shown that this is usually true in XPS to a good approximation. The method is illustrated on experimental non-monochromatized MgK? spectra of Au acquired at different detection angles but for the same angle of incidence of the X-rays.

Werner, Wolfgang S. M.; Cabela, Thomas; Zemek, Josef; Jiricek, Petr

2001-01-01

118

X-ray spectroscopy of kaonic atoms at SIDDHARTA  

NASA Astrophysics Data System (ADS)

The X-ray measurements of kaonic atoms play an important role for understanding the low-energy QCD in the strangeness sector. The SIDDHARTA experiment studied the X-ray transitions of 4 light kaonic atoms (H, D, 3He, and 4He) using the DAFNE electron-positron collider at LNF (Italy). Most precise values of the shift and width of the kaonic hydrogen 1s state were determined, which have been now used as fundamental information for the low-energy K-p interaction in theoretical studies. An upper limit of the X-ray yield of kaonic deuterium was derived, important for future K-d experiments. The shifts and widths of the kaonic 3He and 4He 2p states were obtained, confirming the end of the "kaonic helium puzzle". In this contribution also the plans for new experiments of kaonic deuterium are being presented.

Cargnelli, M.; Bazzi, M.; Beer, G.; Berucci, C.; Bragadireanu, A. M.; Curceanu, C.; d'Uffizi, A.; Fiorini, C.; Ghio, F.; Guaraldo, C.; Hayano, R.; Iliescu, M.; Ishiwatari, T.; Iwasaki, M.; Levi Sandri, P.; Marton, J.; Okada, S.; Pietreanu, D.; Ponta, T.; Quaglia, R.; Romero Vidal, A.; Sbardella, E.; Scordo, A.; Shi, H.; Sirghi, D. L.; Sirghi, F.; Tatsuno, H.; Vazquez Doce, O.; Widmann, E.; Wünschek, B.; Zmeskal, J.

2014-06-01

119

Broad-band soft x-ray diagnostic instruments at the LLNL Novette laser facility  

Microsoft Academic Search

Complementary broad-band instruments have been developed to measure time dependent, absolute soft x-ray spectra at the Lawrence Livermore National Laboratory (LLNL) Nd glass laser irradiation facilities. Absolute flux measurements of x rays emitted from laser-produced plasmas are important for understanding laser absorption and energy transport. We will describe two new 10-channel XRD systems that have been installed at the LLNL

K. G. Tirsell; P. H. Y. Lee; D. G. Nilson; H. Medecki

1983-01-01

120

Instrument Series: Spectroscopy and Diffraction XPS Imaging  

E-print Network

Instrument Series: Spectroscopy and Diffraction XPS Imaging The X-ray photoelectron spectroscopy (XPS) imaging system provides fast, quantitative, real-time parallel imaging with highest resolution and full-size glove box Ã? Automated Ar+ and cluster ion gun Enable angle-dependent XPS depth profile

121

The BioCAT undulator beamline 18ID: A facility for biological non-crystalline diffraction and x-ray absorption spectroscopy at the APS  

SciTech Connect

The 18ID undulator beamline of the Biophysics Collaborative Access Team at the Advanced Photon Source, Argonne, IL, USA, is a high-performance instrument designed for, and dedicated to, the study of partially ordered and disordered biological materials using the techniques of small-angle X-ray scattering, fiber diffraction, and X-ray absorption spectroscopy. The beamline and associated instrumentation are described in detail and examples of the representative experimental results are presented.

Fischetti, R.; Stepanov, S.; Rosenbaum, G.; Barrea, R.; Black, E.; Gore, D.; Heurich, R.; Kondrashkina, E.; Kropf, A.J.; Wang, S.; Zhang, K.; Irving, T.C.; Bunker, G.B. (IIT); (Georgia)

2008-07-02

122

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

123

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

124

Solar X-Ray Spectroscopy and Optical Line Polarimetry.  

National Technical Information Service (NTIS)

An experiment was performed to measure the X-ray spectrum of the solar corona between 1.8 and 5.4A. Panels of mosaic graphite crystals were used as dispersive elements and proportional counters as detectors. The spectrometer was carried aloft by an Aerobe...

J. R. P. Angel, M. C. Weisskopf, R. Novick, R. S. Wolff

1973-01-01

125

Si(Li) X-ray astronomical spectroscopy  

NASA Technical Reports Server (NTRS)

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

Holt, S. S.

1975-01-01

126

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

127

HIGH RESOLUTION X-RAY SPECTROSCOPY WITH A MICROCALORIMETER  

Microsoft Academic Search

Energy-dispersive spectrometry (EDS) is often the preferred choice for X-ray microanalysis, but there are still many disadvantages associated with EDS, the most significant of which is the relatively poor energy resolution, which limits detection sensitivity and the ability to distinguish among closely spaced spectral features, limiting even qualitative analysis. A new type of EDS detector that operates on the principle

JOHANNES NORRELL; IAN ANDERSON

128

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

129

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.

130

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

131

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

NASA Technical Reports Server (NTRS)

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

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

1996-01-01

132

X-ray photoelectron spectroscopy in the hard x-ray regime  

Microsoft Academic Search

Photoelectron spectroscopy is by now a very widely used tool for the study of atoms, molecules, solids, surfaces, and nanoscale structures. Until very recently, the exciting radiation has been limited to the energy range below about 2 keV. However, within the past few years, a few experimental projects have been initiated in which photon energies in the 5-15 keV range

Charles S. Fadley

2006-01-01

133

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

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

Measuring Black Hole Spin Using X-Ray Reflection Spectroscopy  

NASA Astrophysics Data System (ADS)

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

Reynolds, Christopher S.

2014-09-01

136

X-Ray Spectroscopy of Bromine Compounds and Biomedical Applications  

Microsoft Academic Search

In conventional biomedical applications intense and broadband high energy X-rays are used in therapy and diagnostics (theranostics) to ensure sufficient tissue penetration for imaging or treatment. To avoid damages incurred by these, our proposed method, Resonant Theranosticsb,c, aims to find narrow energy regions that corresponds to resonant absorption or emission. We show that such energy bands lie below the K-shell

Sultana N. Nahar; Yi Luo; Linh Le; A. K. Pradhan; E. Chowdhury; R. Pitzer; M. Montenegro

2010-01-01

137

Optical spectroscopy of X-ray: Selected active galactic nuclei  

Microsoft Academic Search

Optical spectra of 65 X-ray selected active galactic nuclei (XAGN) from several identification samples are presented. From analysis of their spectra and optical continuum luminosities, the XAGN are classified as follows: 13 quasars, 10 narrow line Seyfert 1 galaxies, 3 Seyfert 1.5's, 3 Seyfert 2's, 1 Seyfert 1.9, 1 HII region-like galaxy and 3 galaxies with very weak emission. The

Sally Anne Stephens

1987-01-01

138

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

139

Spectroscopy of Optical Counterparts of Ultraluminous X-ray Sources  

E-print Network

Here we present the results of panoramic and long-slit observations of eight ULX nebular counterparts held with the 6m SAO telescope. In two ULXNe we detected for the first time signatures of high excitation ([OIII]5007 / H\\beta > 5). Two of the ULXs were identified with young (T ~ 5-10 Myr) massive star clusters. Four of the eight ULX Nebulae (ULXNe) show bright high-excitation lines. This requires existence of luminous (~ 10^{38} .. 10^{40} erg/s) UV/EUV sources coinciding with the X-ray sources. Other 4 ULXNe require shock excitation of the gas with shock velocities of 20-100km/s. However, all the studied ULXN spectra show signatures of shock excitation, but even those ULXNe where the shocks are prevailing show presence of a hard ionizing source with the luminosity at least ~10^{38} erg/s. Most likely shock waves, X-ray and EUV ionization act simultaneously in all the ULXNe, but they may be roughly separated in two groups, shock-dominated and photoionization-dominated ULXNe. The ULXs have to produce strong winds and/or jets powering their nebulae with \\~10^{39} erg/s. Both the wind/jet activity and the EUV source needed are consistent with the suggestion that ULXs are high-mass X-ray binaries with the supercritical accretion disks of the SS433 type.

P. Abolmasov; S. Fabrika; O. Sholukhova; V. Afanasiev

2006-12-28

140

High Resolution X-Ray Spectroscopy with a Microcalorimeter  

SciTech Connect

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

Norrell, J.; Anderson, I.

2005-01-01

141

Energy calibrations in the x-ray absorption spectroscopy of uranium dioxide  

SciTech Connect

Proper and accurate placement of the components of the unoccupied density of states in uranium dioxide requires a careful calibration of the energy scales in the spectroscopic investigations. Here, the energy scale calibrations and corresponding spectroscopic measurements are described in detail, including photoelectron spectroscopy, inverse photoelectron spectroscopy and, most important, x-ray absorption spectroscopy.

Yu, Sung Woo; Tobin, J. G.; Olalde-Velasco, Paul; Yang, Wan Li; Siekhaus, Wigbert J. [Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 and Instituto de Ciencias Nucleares, UNAM, Distrito Federal 04510 (Mexico); Advanced Light Source, Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Lawrence Livermore National Laboratory, Livermore, California 94550 (United States)

2012-01-15

142

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

NASA Astrophysics Data System (ADS)

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

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

2007-09-01

143

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

SciTech Connect

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

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

2011-08-16

144

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

145

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

NASA Technical Reports Server (NTRS)

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

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

1993-01-01

146

Broad-band soft x-ray diagnostic instruments at the LLNL Novette laser facility  

SciTech Connect

Complementary broad-band instruments have been developed to measure time dependent, absolute soft x-ray spectra at the Lawrence Livermore National Laboratory (LLNL) Nd glass laser irradiation facilities. Absolute flux measurements of x rays emitted from laser-produced plasmas are important for understanding laser absorption and energy transport. We will describe two new 10-channel XRD systems that have been installed at the LLNL Novette facility for use in the 0.15- to 1.5-keV range. Since XRD channel time response is limited by available oscilloscope performance to 120 ps, a soft x-ray streak camera has been developed for better time resolution (20 ps) and greater dynamic range (approx.10/sup 3/) in the same x-ray energy region. Using suitable filters, grazing incidence mirrors, and a gold or cesium-iodide transmission cathode, this streak camera instrument has been installed at Novette to provide one broad and four relatively narrow channels. It can also be used in a single channel, spatially discriminating mode by means of pinhole imaging. The complementary nature of these instruments has been enhanced by locating them in close proximity and matching their channel energy responses. As an example of the use of these instruments, we present results from Novette 2..omega..(0.53 ..mu..m) gold disk irradiations at 1 ns and 10/sup 14/ to 10/sup 15/ W/cm/sup 2/.

Tirsell, K.G.; Lee, P.H.Y.; Nilson, D.G.; Medecki, H.

1983-09-15

147

Mineralogy by X-ray Diffraction on Mars: The Chemin Instrument on Mars Science Laboratory  

NASA Technical Reports Server (NTRS)

To obtain detailed mineralogy information, the Mars Science Laboratory rover Curiosity carries CheMin, the first X-ray diffraction (XRD) instrument used on a planet other than Earth. CheMin has provided the first in situ XRD analyses of full phase assemblages on another planet.

Vaniman, D. T.; Bristow, T. F.; Bish, D. L.; Ming, D. W.; Blake, D. F.; Morris, R. V.; Rampe, E. B.; Chipera, S. J.; Treiman, A. H.; Morrison, S. M.; Achilles, C. N.; Downs, R. T.; Farmer, J. D.; Crisp, J. A.; Morookian, J. M.; Des Marais, D. J.; Grotzinger, J. P.; Sarrazin, P.; Yen, A. S.

2014-01-01

148

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

149

Densities of states of black phosphorus by soft X-ray spectroscopy  

Microsoft Academic Search

We report the results of a soft X-ray investigation of the valence and conduction states of black phosphorus from which the p and s states distributions are obtained separately. The presence of pure p states is found at the upper part of the valence band. Good agreement is found with recent X-ray photoelectron spectroscopy data and with a theoretical density-of-states

Esther Belint; Christiane Sénémaud; András Szász

1988-01-01

150

New developments in fabrication of high-energy-resolution analyzers for inelastic X-ray spectroscopy  

PubMed Central

In this work new improvements related to the fabrication of spherical bent analyzers for 1?meV energy-resolution inelastic X-ray scattering spectroscopy are presented. The new method includes the use of a two-dimensional bender to achieve the required radius of curvature for X-ray analyzers. The advantage of this method is the ability to monitor the focus during bending, which leads to higher-efficiency analyzers. PMID:21525659

Said, Ayman H.; Sinn, Harald; Divan, Ralu

2011-01-01

151

Study of silicon carbide for X-ray detection and spectroscopy  

Microsoft Academic Search

This work presents an analysis of silicon carbide (SiC) as semiconductor for the realization of detectors for soft X-rays (<20 keV). On the basis of experimental data on prototype SiC junctions, the performance in X-ray spectroscopy using planar diode and drift detectors in SiC have been estimated in a wide range of operating temperature (up to 150°C). It has been

Giuseppe Bertuccio; Roberto Casiraghi

2003-01-01

152

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

PubMed Central

Understanding the excitation energy transfer mechanism in multiporphyrin arrays is key for designing artificial light-harvesting devices and other molecular electronics applications. Simulations of the stimulated X-ray Raman spectroscopy signals of a Zn/Ni porphyrin heterodimer induced by attosecond X-ray pulses show that these signals can directly reveal electron–hole pair motions. These dynamics are visualized by a natural orbital decomposition of the valence electron wavepackets. PMID:24019462

Zhang, Yu; Healion, Daniel; Mukamel, Shaul

2013-01-01

153

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

154

Characterization of aluminium surfaces with and without plasma nitriding by X-ray photoelectron spectroscopy  

Microsoft Academic Search

Substrates of aluminium alloy 2011 have been plasma nitrided using an inductively coupled plasma source and then characterised by X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The XRD analysis confirmed the presence of a crystalline aluminium nitride (AlN) layer on the substrates surfaces. Both AlN and Al2O3 were observed by XPS on the surface of the nitrided Al substrates.

Sabina Gredelj; Andrea R Gerson; Sunil Kumar; Giuseppe P Cavallaro

2001-01-01

155

X-ray absorption spectroscopy studies of nickel oxide thin film electrodes for supercapacitors  

Microsoft Academic Search

Nickel oxide films were synthesized by electrochemical precipitation of Ni(OH)2 followed by heat-treatment in air at various temperatures (200–600°C). Their structure and electrochemical properties were studied by cyclic voltammetry, X-ray diffraction (XRD) and X-ray absorption spectroscopy (XAS). XRD results showed that the nickel oxide obtained at 250°C or above has a crystalline NiO structure. The specific capacitance of the oxide

Kyung-Wan Nam; Won-Sub Yoon; Kwang-Bum Kim

2002-01-01

156

X-Ray Spectroscopy of Bromine Compounds and Biomedical Applications  

NASA Astrophysics Data System (ADS)

In conventional biomedical applications intense and broadband high energy X-rays are used in therapy and diagnostics (theranostics) to ensure sufficient tissue penetration for imaging or treatment. To avoid damages incurred by these, our proposed method, Resonant Theranosticsb,c, aims to find narrow energy regions that corresponds to resonant absorption or emission. We show that such energy bands lie below the K-shell ionization energy, contrary to the research focus on the K-shell ionization energy itself. Targeting these energy bands, Auger processes can be initiated to produce a number of photons and electrons from each atomic/molecular species via photon fluorescence and electron ejections. We will report our study on the bromine compound bromodeoxyuridyne (BUdR), widely used as radiological contrast agent in radiation imaging. The active system is Br^o-Br^+ combination, which can emit or absorb X-rays in the relative narrow energy range of 12 to 13.6 keV, through 1s-np transitions. We will present the oscillator strengths and transition probabilities for various Auger or K-shell 1s-np transitions. We will show that the corresponding cross sections and attenuation coefficients per unit mass, are orders of magnitude higher than the background and that at K-shell ionization energy. Employing these attenuation coefficients in the Monte Carlo simulation program Geant4, we study the intensities of photon and electron emission spectra. Acknowledgment: Partially support: Large Interdisciplinary Grant award of the Ohio State University and NASA (SNN). The computational work was carried out at the Ohio Supercomputer Center, Columbus Ohio. "Resonant X-Ray Enhancement of the Auger Effect in High-Z atoms, molecules, and Nanoparticles: Biomedical Applications", A. K. Pradhan, S. N. Nahar, M. Montenegro, Yan Yu, H. L. Zhang, C. Sur, M. Mrozik, R. M. Pitzer, J. of Phys. Chem. A, 113 (2009), 12356. "Monte Carlo Simulations and Atomic Calculations for Auger Processes in Biomedical Nanotheranostics", M. Montenegro, S. N. Nahar, A. K. Pradhan, Ke Huang, Yan Yu, J. of Phys. Chem. A, 113 (2009), 12364.

Nahar, Sultana N.; Luo, Yi; Le, Linh; Pradhan, A. K.; Chowdhury, E.; Pitzer, R.; Montenegro, M.

2010-06-01

157

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

NASA Technical Reports Server (NTRS)

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

Lin, R. P.

1983-01-01

158

X-ray imaging and spectroscopy using low cost COTS CMOS sensors  

NASA Astrophysics Data System (ADS)

Whilst commercial X-ray sensor arrays are capable of both imaging and spectroscopy they are currently expensive and this can limit their widespread use. This study examines the use of very low cost CMOS sensors for X-ray imaging and spectroscopy based on the commercial off the shelf (COTS) technology used in cellular telephones, PC multimedia and children's toys. Some examples of imaging using a 'webcam' and a modified OmniVision OV7411 sensor are presented, as well as a simple energy dispersive X-ray detector based on an OmniVision OV7221 sensor. In each case X-ray sensitivity was enabled by replacing the sensor's front glass window with a 5 ?m thick aluminium foil, with X-rays detected as an increase in a pixel's dark current due to the generation of additional electron-hole pairs within its active region. The exposure control and data processing requirements for imaging and spectroscopy are discussed. The modified OV7221 sensor was found to have a linear X-ray energy calibration and a resolution of approximately 510 eV.

Lane, David W.

2012-08-01

159

X-ray Fluorescence Spectroscopy: the Potential of Astrophysics-developed Techniques  

NASA Astrophysics Data System (ADS)

X-ray fluorescence from the surface of airless bodies has been studied since the Apollo X-ray fluorescence experiment mapped parts of the lunar surface in 1971-1972. That experiment used a collimated proportional counter with a resolving power of ~1 and a beam size of ~1degree. Filters separated only Mg, Al and SI lines. We review progress in X-ray detectors and imaging for astrophysics and show how these advances enable much more powerful use of X-ray fluorescence for the study of airless bodies. Astrophysics X-ray instrumentation has developed enormously since 1972. Low noise, high quantum efficiency, X-ray CCDs have flown on ASCA, XMM-Newton, the Chandra X-ray Observatory, Swift and Suzaku, and are the workhorses of X-ray astronomy. They normally span 0.5 to ~8 keV with an energy resolution of ~100 eV. New developments in silicon based detectors, especially individual pixel addressable devices, such as CMOS detectors, can withstand many orders of magnitude more radiation than conventional CCDs before degradation. The capability of high read rates provides dynamic range and temporal resolution. Additionally, the rapid read rates minimize shot noise from thermal dark current and optical light. CMOS detectors can therefore run at warmer temperatures and with ultra-thin optical blocking filters. Thin OBFs mean near unity quantum efficiency below 1 keV, thus maximizing response at the C and O lines.such as CMOS detectors, promise advances. X-ray imaging has advanced similarly far. Two types of imager are now available: specular reflection and coded apertures. X-ray mirrors have been flown on the Einstein Observatory, XMM-Newton, Chandra and others. However, as X-ray reflection only occurs at small (~1degree) incidence angles, which then requires long focal lengths (meters), mirrors are not usually practical for planetary missions. Moreover the field of view of X-ray mirrors is comparable to the incident angle, so can only image relatively small regions. More useful are coded-aperture imagers, which have flown on ART-P, Integral, and Swift. The shadow pattern from a 50% full mask allows the distribution of X-rays from a wide (10s of degrees) field of view to be imaged, but uniform emission presents difficulties. A version of a coded-aperture plus CCD detector for airless bodies study is being built for OSIRIS-REx as the student experiment REXIS. We will show the quality of the spectra that can be expected from this class of instrument.

Elvis, M.; Allen, B.; Hong, J.; Grindlay, J.; Kraft, R.; Binzel, R. P.; Masterton, R.

2012-12-01

160

X-ray Spectroscopy for Quality Control of Chemotherapy Drugs  

NASA Astrophysics Data System (ADS)

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.; Angeli-Greaves, M.; Barros, H.; Bermudez, J.; Sajo-Bohus, L.

2007-10-01

161

X-ray spectroscopy of the first z>7 QSO  

NASA Astrophysics Data System (ADS)

We have recently discovered the most distant QSO, ULAS J1120+0641, at z=7.085, just 760 Myr after the big bang. As the first luminous, persistent source to be discovered at z>7, ULAS J1120 is a unique probe of the intergalactic medium deep in the epoch of reionization, and already constrains the neutral fraction to be more than 10% at z=7. Its black hole is estimated to be 2.0e9 Msun, and the small size of the ionized region in which it is embedded implies it has been shining for less than 10^7 yrs. Thus it also provides important constraints on the formation and evolution of massive black holes. We propose to obtain an X-ray spectrum with XMM-Newton to examine the physical conditions in this young QSO, and to better determine its ionizing spectrum for reionization modelling.

Page, Mathew

2011-10-01

162

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

163

Total reflection x-ray fluorescence spectroscopy (TXRF) a new high sensitivity (PPT) quantitative method for forensic and environmental samples  

SciTech Connect

Total Reflection X-Ray Fluorescence (TYRF) Spectroscopy instrumentation has recently become available on the U.S. commercial market. This x-ray excited method is touted for its sensitivity (parts per trillion), quantitative ability without the need for multi-element standards and lack of response change to matrix element differences. It has been promoted for use in forensic science and on environmental samples. This paper will discuss the results of a blind studies, wherein well characterized samples of forensic interest and environmental water proficiency tests were submitted for determination of elemental composition and concentration. The results indicate that this instrumentation should be considered by those laboratories analyzing materials at low (trace) concentrations or small (microscopical) size.

Kubic, T.A.; Amray, M.S. [ATOMIKA, Bedford, MA (United States); Reus, U. [ATOMKIA Instruments, Munich (Germany)] [and others

1995-12-31

164

Extended X-ray absorption fine structure spectroscopy of selenium-hyperdoped silicon  

E-print Network

Extended X-ray absorption fine structure spectroscopy of selenium-hyperdoped silicon Bonna K-ray absorption fine structure (EXAFS) spectroscopy to probe the chemical states of selenium dopants in selenium-hyperdoped silicon annealed to varying degrees. We observe a smooth and continuous selenium chemical state change

165

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

E-print Network

studies which are being made in one of these new fields - the matter of the chemical properties-ray spectroscopy . . . . . . . . . . . . . 3 2.2 Interpretation of the chemical shift in X-ray spectroscopy and Conclusions 18 Abstract A review with historical emphasis is given of the discovery and evaluation of chem

Lindgren, Ingvar

166

Cerium oxidation state in ceria nanoparticles studied with X-ray photoelectron spectroscopy and absorption near edge spectroscopy  

Microsoft Academic Search

X-ray photoelectron spectroscopy and X-ray absorption near edge spectroscopy experiments are used to investigate the oxidation state of cerium ions in ceria nanoparticles. A comparison of results shows that XPS yields a higher concentration of Ce3+ ions, even after analysis with a core–shell model. Three factors are proposed for the discrepancy between results: surface reduction of ceria in the XPS

Feng Zhang; Peng Wang; J. Koberstein; S. Khalid; Siu-Wai Chan

2004-01-01

167

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

NASA Astrophysics Data System (ADS)

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:LuVO 4 single crystal grown by the slow cooling method have been studied by means of X-ray diffraction topography employing white synchrotron beam, high-resolution diffraction (HRD) and photoelectron spectroscopy (XPS) techniques. Topographic investigations show that the crystal is composed of two blocks disoriented by about 1.5° and separated by a narrow deformed region. Some contrasts observed within the crystal volume may be attributed to glide bands and sector boundaries. The contrasts appearing in the vicinity of the surface may be interpreted as due to the presence of small inclusions. The HRD study indicates, in particular, that among point defects, the vacancy type defects dominate and that the density of other defects is small in comparison. The XPS measurements enabled, despite highly insulating properties of the studied crystal, an analysis of its bulk electronic structure, including the main core-levels (O 1 s, V 2 p, Lu 4 f) as well as the valence band range.

Paszkowicz, W.; Romanowski, P.; B?k-Misiuk, J.; Wierzchowski, W.; Wieteska, K.; Graeff, W.; Iwanowski, R. J.; Heinonen, M. H.; Ermakova, O.; D?bkowska, H.

2011-10-01

168

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; Grubel, Gerhard

2011-01-01

169

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

Microsoft Academic Search

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

Balwant Singh; Markus Gräfe; Navdeep Kaur; Andrea Liese

2010-01-01

170

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 ABSTRACT Long known to be an unusual early-type star by virtue of its hard and strong X-ray emission, Scorpii poses a severe challenge to the standard picture of O-star wind-shock X-ray emission. The Chandra

Cohen, David

171

High-resolution x-ray saturation spectroscopy of krypton L-shell autoionizing transitions  

NASA Astrophysics Data System (ADS)

The achievement of controlled saturation with high spectral resolution (˜2-3 eV) provides a refined diagnostic for the quantitative study of the propagation of intense beams of x-rays. This work demonstrates the characteristics of saturation spectroscopy with an analysis of Kr(L) autoionizing transitions at ?? = 1652 eV. The data include single-pulse x-ray spatial morphologies, corresponding Thomson images of the electron density, and spatially resolved transversely observed x-ray spectra that are recorded longitudinally along the direction of propagation of a Kr26+ (?26 = 7.504 Å) beam in a Kr n cluster medium. The results reveal the complex interactions associated with the propagation of the 7.504 Å x-ray beam and, based on sets of quantitative criteria, attribute the observed behavior to the saturation of 2p ? 3d transitions to autoionizing states of Kr15+ and Kr16+ ionic species.

Borisov, Alex B.; McCorkindale, John C.; Poopalasingam, Sankar; Longworth, James W.; Rhodes, Charles K.

2014-09-01

172

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

NASA Astrophysics Data System (ADS)

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

Kaastra, J. S.

2004-05-01

173

Ultra-soft x-ray absorption spectroscopy: A bulk and surface probe of materials  

SciTech Connect

Direct comparisons between surface and bulk of diverse materials can be made by simultaneous electron yield (5 nm depth sensitivity) and fluorescence yield (200 nm) ultra soft x-ray absorption spectroscopy measurements utilizing a rapid sample interchange apparatus. For example the orientations of functional groups have been characterized at and near the surface of a series of model polymeric materials highlighting the chemical and molecular sensitivity of ultra soft x-ray absorption spectroscopy. In addition we discuss a bulk sensitive use of fluorescence yield to non destructively study a buried metal polymer interface. A second bulk sensitive example is the use of fluorescence yield oxygen K near edge x-ray spectroscopy as a method to determine the hole state density of high Tc materials.

Fischer, D.A. [National Institute of Standards and Technology, Gaithersburg, MD (United States); Mitchell, G.E.; Dekoven, B.M. [Dow Chemical Co., Midland, MI (United States); Yeh, A.T.; Gland, J.L. [Michigan Univ., Ann Arbor, MI (United States); Moodenbaugh, A.R. [Brookhaven National Lab., Upton, NY (United States)

1993-06-01

174

Spitzer Mid-Infrared Spectroscopy of Distant X-ray Luminous AGN  

E-print Network

We present mid-infrared spectroscopy of a sample of 16 optically faint infrared luminous galaxies obtained with the Infrared Spectrograph (IRS) on the Spitzer Space Telescope. These sources were jointly selected from Spitzer and Chandra imaging surveys in the NDWFS Bootes field and were selected from their bright X-ray fluxes to host luminous AGN. None of the spectra show significant emission from polycyclic aromatic hydrocarbons (PAHs; 6.2um equivalent widths <0.2um), consistent with their infrared emission being dominated by AGN. Nine of the X-ray sources show 9.7um silicate absorption features. Their redshifts are in the range 0.9X-ray selection favors sources behind a smaller column of Si-rich dust than non-X-ray selection. Seven of the X-ray sources have featureless power-law mid-IR spectra. We argue that the featureless spectra likely result from the sources having weak or absent silicate and PAH features rather than the sources lying at higher redshifts where these features are shifted out of the IRS spectral window. We investigate whether there are any correlations between X-ray and infrared properties and find that sources with silicate absorption features tend to have fainter X-ray fluxes and harder X-ray spectra, indicating a weak relation between the amount of silicate absorption and column density of X-ray-absorbing gas.

Kate Brand; Dan W. Weedman; Vandana Desai; Emeric Le Floc'h; Lee Armus; Arjun Dey; Jim R. Houck; Buell T. Jannuzi; Howard A. Smith; B. T. Soifer

2008-01-30

175

FORTRAN program for x ray photoelectron spectroscopy data reformatting  

NASA Technical Reports Server (NTRS)

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.

1989-01-01

176

Electronic structure of silicon nitride studied by both soft x-ray spectroscopy and photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The valence and conduction band states of crystalline silicon nitride ?-Si3N4 have been studied by using two complementary experimental methods. The total valence band distribution has been analyzed by x-ray induced photoelectron spectroscopy. The Si 3p valence states and the Si p conduction states have been probed selectively by x-ray emission and absorption spectroscopies, respectively. The experimental curves have been compared in the same energy scale referred to the Fermi level. Our results show clearly that the N 2p? states of Si3N4 are located at the top of the valence band while Si 3p states, mixed to N 2p states and, respectively, to N 2s states are located at about EF-8.4 eV and EF-19.6 eV. Our experimental results are in very good agreement with theoretical simulations of the spectra made from recent density of states calculations by Robertson [Philos. Mag. B 63, 47 (1991)] in a tight binding approach.

Sénémaud, C.; Driss-Khodja, M.; Gheorghiu, A.; Harel, S.; Dufour, G.; Roulet, H.

1993-10-01

177

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

178

Analysis of hard carbon for lithium-ion batteries by hard X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Non-graphitizable carbon (hard carbon) as a negative electrode material for lithium-ion batteries is investigated by X-ray photoelectron spectroscopy, and hard X-ray photoelectron spectroscopy (HX-PES). HX-PES spectra have peaks of both the solid electrolyte interphase on the hard carbon surface and the hard carbon itself. The change in spectrum with state of charge is observed by HX-PES. Hard carbon has two types of lithium insertion site; between graphene sheets and into nano-scale voids. These spectroscopic results are consistent with the lithium insertion mechanism into hard carbon.

Hori, Hironobu; Shikano, Masahiro; Kobayashi, Hironori; Koike, Shinji; Sakaebe, Hikari; Saito, Yoshiyasu; Tatsumi, Kuniaki; Yoshikawa, Hideki; Ikenaga, Eiji

2013-11-01

179

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

180

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

PubMed

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 [Formula: see text] and [Formula: see text] 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. PMID:24981531

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

2013-04-14

181

Recent Advances in Instrumentation for High Resolution Inelastic X-ray Scattering and Nuclear Resonant Scattering  

Microsoft Academic Search

We discuss recent advances in instrumentation for high resolution inelastic x-ray scattering and nuclear resonant scattering of synchrotron radiation at BL35XU. Notable points are demonstration of the backscattering monochromator performance over long scan ranges, significant improvements in analyzer crystal perfection and a setup for nuclear scattering from the 25.6 keV resonance of 161 Dy. The last includes a new compact

A. Q. R. Baron; Yoshikazu Tanaka; D. Miwa; D. Ishikawa; T. Mochizuki; H. Kimura; F. Yamamoto; Mikazuki Kouto

2001-01-01

182

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

183

Feasibility of an integrated X-ray instrument for Mars exobiology and geology. [Abstract only  

NASA Technical Reports Server (NTRS)

By employing an integrated X-ray instrument on a future Mars mission, data obtained will greatly augment those returned by Viking; details relevant to the possibility of the origin and evolution of life on Mars will be acquired. An integrated combined X Ray Fluorescence/X Ray Detection (XRF/XRD) instrument has been breadboarded and demonstrated to accommodate important exobiology and geology experiment objectives outlined for Mars Environmental Survey (MESUR) and future Mars missions. Among others, primary objectives for the exploration of Mars include: the intense study of local areas on Mars to 'establish the chemical, mineralogical, and petrological character of different components of the surface material; to determine the distribution, abundance and sources and sinks of volatile materials, including an assessment of the biologic potential, now and during past epochs; and to establish the global chemical and physical characteristics of the Martian surface'. The XRF/XRD breadboard instrument identifies and quantifies soil surface elemental, mineralogical, and petrological characteristics and acquires data necessary to address questions on volatile abundance and distribution. Additionally, the breadboard is able to characterize the biogenic element constituents of soil samples providing information on the biologic potential of the Mars environment.

Fonda, M. L.; Schwartz, D. E.; Koppel, L. N.; Franco, E. D.; Kerner, J. A.

1994-01-01

184

Ultrafast laser-driven x-ray spectrometer for x-ray absorption spectroscopy of transition metal complexes.  

PubMed

We report what are to our knowledge the first measurements of an x-ray absorption near-edge structure (XANES) spectrum of solvated iron pentacarbonyl by use of an ultrafast laser-driven plasma x-ray source. This source is operating at a 2-kHz repetition rate. Hard x radiation that might falsify the XANES measurements is suppressed by an x-ray optical setup that consists of a fiber-optic lens and a silicon single crystal. PMID:15143663

Benesch, Frank; Lee, Taewoo; Jiang, Yan; Rose-Petruck, Christoph G

2004-05-01

185

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

186

Cosmic X-ray Physics: A Suborbital Investigation of the Diffuse X-ray Background Including Instrumentation Development  

NASA Astrophysics Data System (ADS)

We propose an investigation to improve our understanding of the Galactic diffuse X-ray background. The ultimate purpose of this is to determine the role of hot phases of the interstellar medium in mediating stellar feedback in star formation, in transport of metals, and in determining the structure and evolution of the Galaxy. This work will involve a flight of an existing payload with small modifications in Woomera, South Australia, to observe the Galactic soft X-ray bulge and attempt to determine its nature and emission mechanisms. It will also involve the development of detectors capable of 1-2 eV FWHM energy resolution in the 100-400 eV range with the intent of obtaining a scientifically useful spectrum on a sounding rocket flight of the emission from one million degree gas in this energy range. This will require a total area of 1-2 cm^2 for the detector array. With the collaboration and advice of microwave experts at the Goddard Space Flight Center, we will fabricate and test waveguide-below-cutoff filters to provide the necessary attenuation of infrared radiation for these detectors while still allowing relatively good x- ray transmission below 300 eV. The detectors, filters, and flight experience with the detector readouts are all relevant to future NASA major missions. The filters would be particularly valuable in allowing thermal detectors (microcalorimeters) similar to those used here in the X-ray range to be applied to the EUV and vacuum ultraviolet, where they offer large potential gains over existing detectors. These investigations will provide the primary training for our graduate students, and will involve a substantial number of undergraduates.

McCammon, Dan

187

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

188

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

189

X-ray spectroscopy of the unsteady quiescent corona of AD Leo with Chandra  

E-print Network

also show that the EMD is compatible with the model of a corona continuously heated by ares, which in stellar coronae and the nature of coronal heating. The topology, surface coverage and strength of the coroX-ray spectroscopy of the unsteady quiescent corona of AD Leo with Chandra A. Maggio 1 , J.J. Drake

190

Quantitative characterization of catalyst layer degradation in PEM fuel cells by X-ray photoelectron spectroscopy  

Microsoft Academic Search

A quantitative analysis of catalyst layer degradation was performed with X-ray photoelectron spectroscopy (XPS). XPS is quantitative, surface-sensitive, and is able to distinguish different bonding environments or chemical states of fuel cell catalyst layers and polymer electrolyte membrane. These capabilities have allowed us to explore the complex mechanisms of degradation during fuel cell operation. The elemental surface concentrations of carbon,

Feng-Yuan Zhang; Suresh G. Advani; Ajay K. Prasad; Mary E. Boggs; Shawn P. Sullivan; Thomas P. Beebe Jr.

2009-01-01

191

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.

192

Ultrasmall-angle X-ray scattering photon correlation spectroscopy over extended length and time scales  

Microsoft Academic Search

X-ray Photon Correlation Spectroscopy (XPCS) is an emerging technique offering unprecedented sensitivity to dynamics of structural changes in materials. Existing XPCS facilities are limited to microstructure length scales less than 50 nm, eliminating large classes of important materials. Recently, the scale range has been extended dramatically by combining XPCS speckle measurements with ultrasmall-angle scattering (USAXS) studies at the Advanced Photon

Andrew Allen; Fan Zhang; Lyle Levine; Jan Ilavsky; Gabrielle Long

2010-01-01

193

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 Microscope (FE-SEM) as shown in Figure 1. The FE-SEM combines the versatility of PC control with a novel mm working distance. The FE-SEM also offers excellent low kV performance with resolution of 2.5 nm

Gelfond, Michael

194

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

Microsoft Academic Search

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

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

1989-01-01

195

Highly Sensitive Nitric Oxide Detection Using X-ray Photoelectron Spectroscopy  

E-print Network

explosives3 so detection of trace amounts of explosive, for example in security screening, also requiresHighly 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

196

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

197

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

198

Probing multilayer spintronic structures with photoelectron and x-ray emission spectroscopies excited by x-ray standing waves (invited)  

NASA Astrophysics Data System (ADS)

We discuss a newly developed x-ray standing-wave/wedge (swedge) method for probing the composition, magnetization, and electronic densities of states in buried interfaces and layers in spintronic nanostructures. In work based on photoemission, this method has permitted determining concentration and magnetization profiles through giant magnetoresistive (GMR) and magnetic tunnel junctions 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 GMR structure. Various future applications of this method in nanomagnetism 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.; Fadley, C. S.

2008-04-01

199

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

200

Interfacial energy-dispersive spectroscopy profile X-ray resolution measurements in variable pressure SEM.  

PubMed

A procedure has been developed to follow degradation of energy-dispersive spectroscopy (EDS) X-ray lateral resolution in a variable pressure scanning electron microscope. This procedure is based on evaluation of the EDS profile shape change for different experimental conditions. Some parameters affecting the X-ray resolution in high-vacuum mode have been taken into account. Good agreement between the simulated and experimental EDS profiles shows the reliability of the proposed procedure. A significant improvement in measurement of the EDS profile interfacial distance (DINT) has been achieved. PMID:24960537

Zoukel, Abdelhalim; Khouchaf, Lahcen; Di Martino, Jean; Ruch, David

2014-10-01

201

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

202

Characterisation of doped-lanthanum gallates by X-ray diffraction and Raman spectroscopy  

Microsoft Academic Search

La1?xSrxGaO3?z (x=0–0.2) and LaGa1?yMyO3?z (y=0–0.2, M=Cr, Mg) were synthesised using the standard solid state technique. The structural changes, with increase in dopant concentration, were investigated using powder X-ray diffraction and Raman spectroscopy. The X-ray diffraction of Sr-doped LaGaO3 shows a shift in the orthorhombic pattern with increase in dopant concentration. At 20 mol% Sr doped on the A-site of LaGaO3

N. M. Sammes; G. A. Tompsett; R. J. Phillips; A. M. Cartner

1998-01-01

203

Characterization of Delhi iron pillar rust by X-ray diffraction, Fourier transform infrared spectroscopy and Mössbauer 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 diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and Mössbauer spectroscopy. The identification of iron hydrogen phosphate hydrate in the crystalline form by XRD was unambiguous. Very weak diffraction from the oxyhydroxides\\/oxides of iron was observed indicating that

R Balasubramaniam; A. V Ramesh Kumar

2000-01-01

204

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

205

XMM-Newton spectroscopy of an X-ray selected sample of RL AGNs  

E-print Network

This paper presents the X-ray spectroscopy of an X-ray selected sample of 25 radio-loud (RL) AGNs extracted from the XBSS sample. The main goal is to study the origin of the X-ray spectral differences usually observed between radio-loud and radio-quiet (RQ) AGNs. To this end, a comparison sample of 53 RQ AGNs has been also extracted from the same XBSS sample and studied together with the sample of RL AGNs. We have focused the analysis on the distribution of the X-ray spectral indices of the power-law component that models the large majority of the spectra in both samples. We find that the mean X-ray energy spectral index is very similar in the 2 samples and close to alpha_X~1. However, the intrinsic distribution of the spectral indices is significantly broader in the sample of RL AGNs. In order to investigate the origin of this difference, we have divided the RL AGNs into blazars and ``non-blazars'', on the basis of the available optical and radio information. We find strong evidence that the broad distribution observed in the RL AGN sample is mainly due to the presence of the blazars. Furthermore, within the blazar class we have found a link between the X-ray spectral index and the value of the radio-to-X-ray spectral index suggesting that the observed X-ray emission is directly connected to the emission of the relativistic jet. This trend is not observed among the ``non-blazars'' RL AGNs. This favours the hypothesis that, in these latter sources, the X-ray emission is not significantly influenced by the jet emission and it has probably an origin similar to the RQ AGNs. Overall, the results presented here indicate that the observed distribution of the X-ray spectral indices in a given sample of RL AGNs is strongly dependent on the amount of relativistic beaming present in the selected sources.

E. Galbiati; A. Caccianiga; T. Maccacaro; V. Braito; R. Della Ceca; P. Severgnini; H. Brunner; I. Lehmann; M. J. Page

2004-10-19

206

Profiling of the SiO2 -SiC Interface Using X-ray Photoelectron Spectroscopy R. N. Ghosh  

E-print Network

XPS system was used to obtain both photoelectron spectra of the sample and spatially resolvedProfiling of the SiO2 - SiC Interface Using X-ray Photoelectron Spectroscopy R. N. Ghosh 1 , SC interface via a surface sensitive probe such as x- ray photoelectron spectroscopy (XPS). Lateral scanning

Ghosh, Ruby N.

207

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

208

X-RAY ABSORPTION SPECTROSCOPY OF YB3+-DOPED OPTICAL FIBERS  

SciTech Connect

Optical fibers doped with Ytterbium-3+ have become increasingly common in fiber lasers and amplifiers. Yb-doped fibers provide the capability to produce high power and short pulses at specific wavelengths, resulting in highly effective gain media. However, little is known about the local structure, distribution, and chemical coordination of Yb3+ in the fibers. This information is necessary to improve the manufacturing process and optical qualities of the fibers. Five fibers doped with Yb3+ were studied using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy and X-ray Absorption Near Edge Spectroscopy (XANES), in addition to Yb3+ mapping. The Yb3+ distribution in each fiber core was mapped with 2D and 1D intensity scans, which measured X-ray fluorescence over the scan areas. Two of the five fibers examined showed highly irregular Yb3+ distributions in the core center. In four of the five fibers Yb3+ was detected outside of the given fiber core dimensions, suggesting possible Yb3+ diffusion from the core, manufacturing error, or both. X-ray absorption spectroscopy (XAS) analysis has so far proven inconclusive, but did show that the fibers had differing EXAFS spectra. The Yb3+ distribution mapping proved highly useful, but additional modeling and examination of fiber preforms must be conducted to improve XAS analysis, which has been shown to have great potential for the study of similar optical fi bers.

Citron, Robert; Kropf, A.J.

2008-01-01

209

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

210

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

211

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

NASA Astrophysics Data System (ADS)

Different dodecanethiol capped Au nanoparticles (NP) with similar sizes (˜2nm) but different ferromagnetic signals at room temperature have been investigated by means of x-ray absorption spectroscopy at the Au L3-edge. The reversion of the x-ray magnetic circular dichroism signal with the change of sign of the external applied magnetic field confirms the location of the magnetism at the Au atoms. In comparison with the Au foil, all the samples present accentuated white lines at the x-ray absorption near-edge structure (XANES) indicating generation of 5d holes in the Au atoms located at surface of the NPs as consequence of a localized charge transfer from the Au surface atoms to the S atoms of the capping agent. XANES spectra reflect differences among the electronic structure of the Au NPs which are compared with the observed different macroscopic magnetic signals.

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

2009-04-01

212

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

213

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

214

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

NASA Astrophysics Data System (ADS)

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

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

2014-06-01

215

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

216

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

217

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

NASA Astrophysics Data System (ADS)

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

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

218

X-ray Photoelectron Spectroscopy Studies of Oxidized and Reduced Ce???Zr???O?(111)  

SciTech Connect

We have studied the electronic structure of oxidized and reduced Ce???Zr???O?(111) using x-ray photoelectron spectroscopy (XPS). The 50 nm thick Ce???Zr???O?(111) film was grown on a YSZ(111) substrate using oxygen assisted molecular beam epitaxy (OPA-MBE). This film has been characterized using in-situ RHEED (reflection high energy electron diffraction) and ex-situ XRD (x-ray diffraction), HRTEM (high energy resolution transmission electron spectroscopy) and RBS (Rutherford backscattering spectroscopy). Surfaces of the Ce???Zr???O?(111) film used in this study is found to be unreconstructed and exhibits the structure of bulk CeO?(111) where Zr atoms occupy the lattice sites of Ce in the fluorite structure of ceria. The extent of surface reduction as a result of vacuum annealing has been reported here in addition to the electronic structure of defect-free Ce???Zr???O?(111) surface.

Azad, Samina; Engelhard, Mark H.; Peden, Charles HF; Thevuthasan, Suntharampillai

2004-12-01

219

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

220

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

221

Glancing Angle Dependence of the X-Ray Emission Measured under Total Reflection Angle X-Ray Spectroscopy (TRAXS) Condition during Reflection High Energy Electron Diffraction Observation  

NASA Astrophysics Data System (ADS)

We measured the glancing angle (?g) dependence of the X-ray emission from Si(111)-\\sqrt{3}×\\sqrt{3}-Ag and ?-\\sqrt{3}×\\sqrt{3}-Au surfaces during Reflection High Energy Electron Diffraction observation under the Total Reflection Angle X-ray Spectroscopy condition. The characteristic X-rays AgL and AuM decreased according to 1/sin ?g. The function 1/\\sin?g is easily understood in terms of Ag and Au atoms located at the top layer of the surface. The SiK and the bremsstrahlung showed broad peaks around 8°. These trends of the curves are explained by an analysis using Monte Carlo electron trajectory simulation. By measuring the glancing angle dependence we can easily distinguish whether or not a specific kind of atom is confined at the top layer of the surface.

Yamanaka, Toshiro; Hanada, Takashi; Ino, Shozo; Daimon, Hiroshi

1992-10-01

222

X-Ray Chemical Analysis of Multilayered Thin Films by Scanning Electron Microscopy and Total-Reflection-Angle X-Ray Spectroscopy  

NASA Astrophysics Data System (ADS)

Scanning electron microscopy and total-reflection-angle X-ray spectroscopy (SEM-TRAXS) have been applied to X-ray chemical analysis of multilayered thin films on Si substrates. Clear differences were observed in the take-off angle (? t) dependence of the X-ray intensities between Pd(10 nm)/Au(10 nm)/Si and Au(10 nm)/Pd(10 nm)/Si structures. The ? t dependence varied with layer thickness increase from 10 to 13 nm. An AlN(30 nm)/Al2O3(30 nm)/Si structure was also successfully analyzed by measuring the ? t dependence of NK ?, OK ?, AlK ? and SiK ? lines.

Yonemitsu, Kyoko; Shibata, Noriyoshi

1994-06-01

223

On Relativistic Disk Spectroscopy in Compact Objects with X-ray CCD Cameras  

E-print Network

X-ray charge-coupled devices (CCDs) are the workhorse detectors of modern X-ray astronomy. Typically covering the 0.3-10.0 keV energy range, CCDs are able to detect photoelectric absorption edges and K shell lines from most abundant metals. New CCDs also offer resolutions of 30-50 (E/dE), which is sufficient to detect lines in hot plasmas and to resolve many lines shaped by dynamical processes in accretion flows. The spectral capabilities of X-ray CCDs have been particularly important in detecting relativistic emission lines from the inner disks around accreting neutron stars and black holes. One drawback of X-ray CCDs is that spectra can be distorted by photon "pile-up", wherein two or more photons may be registered as a single event during one frame time. We have conducted a large number of simulations using a statistical model of photon pile-up to assess its impacts on relativistic disk line and continuum spectra from stellar-mass black holes and neutron stars. The simulations cover the range of current X-ray CCD spectrometers and operational modes typically used to observe neutron stars and black holes in X-ray binaries. Our results suggest that severe photon pile-up acts to falsely narrow emission lines, leading to falsely large disk radii and falsely low spin values. In contrast, our simulations suggest that disk continua affected by severe pile-up are measured to have falsely low flux values, leading to falsely small radii and falsely high spin values. The results of these simulations and existing data appear to suggest that relativistic disk spectroscopy is generally robust against pile-up when this effect is modest.

J. M. Miller; A. D'Ai; M. W. Bautz; S. Bhattacharyya; D. N. Burrows; E. M. Cackett; A. C. Fabian; M. J. Freyberg; F. Haberl; J. Kennea; M. A Nowak; R. C. Reis; T. E. Strohmayer; M. Tsujimoto

2010-09-22

224

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

225

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

NASA Astrophysics Data System (ADS)

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 CoCl2 aqueous solution by X-ray absorption and emission spectroscopy is presented.

Schwanke, C.; Golnak, R.; Xiao, J.; Lange, K. M.

2014-10-01

226

X-ray Photoelectron Spectroscopy Studies of Oxidized and Reduced CeO?(111) Surfaces  

SciTech Connect

We have studied the electronic structure of oxidized and reduced CeO? (111) surfaces using X-ray photoelectron spectroscopy (XPS). The 50 nm thick Co?(111) film was grown on a YSZ(111) substrate using oxygen plasma assisted molecular beam epitaxy (OPA-MBE). This film has been characterized using in-situ RHEED (reflection high energy electron diffraction) and ex-situ XRD (X-ray diffraction), HRTEM (high resolution transmission electron microscopy) and RBS (Rutherford backscattering spectroscopy). The lattice mismatch between CeO?(111) and YSZ(111) is less than 5% and yields a flat surface that is comprised of an equivalent number of Ce?? and O?? ions. Oxidation with O? at 773 K under UHV conditions was sufficient to fully oxidize the CeO?(111). Surface reduction was carried out by annealing in UHV at 973 K.

Engelhard, Mark H.; Azad, Samina; Peden, Charles HF; Thevuthasan, Suntharampillai

2004-12-01

227

X-ray spectroscopy of the photosynthetic oxygen-evolving complex  

SciTech Connect

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

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

2007-04-05

228

X-Ray spectroscopy of the photosynthetic oxygen-evolving complex  

PubMed Central

Water oxidation to dioxygen in photosynthesis is catalyzed by a Mn4Ca cluster with O bridging in Photosystem II (PS II) of plants, algae and cyanobacteria. A variety of spectroscopic methods have been applied to analyzing the participation of the complex. X-ray spectroscopy is particularly useful because it is element-specific, and because it can reveal important structural features of the complex with high accuracy and identify the participation of Mn in the redox chemistry. Following a brief history of the application of X-ray spectroscopy to PS II, an overview of newer results will be presented and a description of the present state of our knowledge based on this approach. PMID:19190720

Sauer, Kenneth; Yano, Junko; Yachandra, Vittal K.

2008-01-01

229

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

NASA Technical Reports Server (NTRS)

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

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

2005-01-01

230

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

PubMed

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 CoCl2 aqueous solution by X-ray absorption and emission spectroscopy is presented. PMID:25362384

Schwanke, C; Golnak, R; Xiao, J; Lange, K M

2014-10-01

231

Toward femtosecond X-ray spectroscopy at the Advanced Light Source  

NASA Astrophysics Data System (ADS)

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 ˜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 DeltaS = 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

232

X-ray photoelectron spectroscopy of rice husk surface modified with maleated polypropylene and silane  

Microsoft Academic Search

Rice husks were subjected to dry-grinding and steam-explosion to reduce their sizes. Subsequently, the surface of rice husk particles was modified using two different coupling agents, maleated polypropylene (MAPP) and ?-aminopropyltriethoxysilane (?-APS, A-1100) to induce chemical reactions between the husk surface and the coupling agents used. The modified surface properties of rice husk were examined using X-ray photoelectron spectroscopy and

Byung-Dae Park; Seung Gon Wi; Kwang Ho Lee; Adya P. Singh; Tae-Ho Yoon; Yoon Soo Kim

2004-01-01

233

Study by X-ray photoelectron spectroscopy of rice husk and the products of its processing  

Microsoft Academic Search

The rice floral glume (husk) and its processing products were studied using X-ray photoelectron spectroscopy. We established\\u000a that the rice husk contained silica in two non-equivalent forms in 1:3 ratio. The predominating form is silicon dioxide, while\\u000a the minor component contains the silicon bound with the organic component which is stable up to ?350°C.

L. A. Zemnukhova; Yu. M. Nikolenko

2011-01-01

234

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

235

Wettability of Silane-Treated Glass Slides as Determined from X-Ray Photoelectron Spectroscopy  

Microsoft Academic Search

The wettability and stability of silane-treated substrates are central in many processes of industrial and environmental interest. Here, we bring the capability of X-ray photoelectron spectroscopy (XPS) to bear on the wettability evaluation of treated glass. For a suite of silane-treated slides we investigate the relationship between wettability and surface composition as determined from XPS. The adhesion behavior and contact

Y. Carolina Araujo; Pedro G. Toledo; Vladimir Leon; Hada Y. Gonzalez

1995-01-01

236

Hard X-ray photoemission spectroscopy for intrinsic electronic structure of strongly correlated electron systems  

Microsoft Academic Search

In order to clarify the intrinsic bulk electronic structure of strongly-correlated electron systems, we have realized hard X-ray photoemission spectroscopy with high energy-resolution at BL29XUL in SPring-8. The total energy resolution of 75meV was achieved at the excitation energy of 5.95keV. Large probing depth of about 100Å enables us to probe intrinsic bulk electronic structure free from surface condition. The

K. Horiba; M. Taguchi; A. Chainani; Y. Takata; N. Kamakura; S. Shin; M. Yabashi; K. Tamasaku; Y. Nishino; D. Miwa; T. Ishikawa; E. Ikenaga; M. Awaji; A. Takeuchi; K. Kobayashi

2006-01-01

237

Measuring surface and grain boundary segregation using wavelength dispersive X-ray spectroscopy  

Microsoft Academic Search

Electron probe microanalysis (EPMA) using wavelength dispersive X-ray spectroscopy (EPMA-WDS) is applied to the quantification of surface and grain boundary monolayer segregation. The case of sulphur segregation in nickel and nickel alloys is considered. It is evidenced that EPMA-WDS is able to detect submonolayer surface segregation. The sulphur segregation can be accurately quantified from the sulphur K? line relative intensity

F. Christien; R. Le Gall

2008-01-01

238

Energy dispersive X-ray spectroscopy analysis on rock samples subjected to piezonuclear tests  

Microsoft Academic Search

\\u000a In the present paper, Energy Dispersive X-ray Spectroscopy (EDS) was performed on different samples of external or fracture\\u000a surfaces coming from specimens used in piezonuclear tests [1,2]. For each sample, different measurements of the same crystalline\\u000a phases (phengite and biotite) were performed in order to get averaged information of the chemical composition and to detect\\u000a possible piezonuclear transmutations from iron

A. Carpinteri; A. Chiodoni; A. Manuello; R. Sandrone

239

Detection of chitosan in Scots pine by Energy Dispersive X-ray Spectroscopy  

Microsoft Academic Search

The aim of this study was to use Energy-Dispersive X-ray Spectroscopy (EDS) to localize chitosan in the cell wall of chitosan impregnated Scots pine. It is of both general and specific interest to investigate the concentration of chitosan in the wood matrix to gain further knowledge and understanding of chitosan as a wood protective system. After deacetylation, chitosan was re-acetylated

E. LARNØY; M. EIKENES; H. MILITZ

240

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

Microsoft Academic Search

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

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

2004-01-01

241

Repair of fractured framework: scanning electron microscopy and energy dispersive X-ray spectroscopy.  

PubMed

Fractured metal prostheses can be analyzed for possible causes of failure using scanning electron microscopy (SEM). In this study, fractography is used to determine the cause of the failure and whether repair is practical. Energy-dispersive x-ray spectroscopy (EDS) is used to determine composition of the fractured prosthesis so that a repair process can be recommended. The technique is presented for the repair of a titanium framework for an implant-supported overdenture based on the analysis data. PMID:15359153

Maalhagh-Fard, Ahmad; Wagner, Warren C

2004-09-01

242

X-Ray photon correlation spectroscopy study of Brownian motion of gold colloids in glycerol  

SciTech Connect

We report x-ray photon correlation spectroscopy studies of the static structure factor and dynamic correlation function of a gold colloid dispersed in the viscous liquid glycerol. We find a diffusion coefficient for Brownian motion of the gold colloid which agrees well with that extrapolated from measurements made with visible light, but which was determined on an optically opaque sample and in a wave-vector range inaccessible to visible light.

Dierker, S.B.; Pindak, R.; Fleming, R.M.; Robinson, I.K.; Berman, L. [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States)] [Department of Physics, University of Michigan, Ann Arbor, Michigan 48109-1120 (United States); [AT& T Bell Laboratories, 600 Mountain Avenue, Murray Hill, New Jersey 07974-0636 (United States); [Department of Physics, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801-3080 (United States); [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973-5000 (United States)

1995-07-17

243

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

Microsoft Academic Search

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

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

1998-01-01

244

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

Microsoft Academic Search

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

Susanne Gier; William D. Johns

2000-01-01

245

Optical metrology for the segmented optics on the Constellation-X spectroscopy x-ray telescope  

Microsoft Academic Search

We present the metrology requirements and metrology implementation necessary to optically characterize the reflector technology for the Constellation-X (C-X) spectroscopy x-ray telescope (SXT). This segmented, 1.6m diameter highly nested telescope presents many metrology and alignment challenges. In particular, these mirrors have a stringent imaging error budget as compared to their intrinsic stiffness. The low stiffness is seen to be implied

David Colella; Theo Hadjimichael; John P. Lehan; Joseph McMann; Paul B. Reid; Timo T. Saha; William W. Zhang

2004-01-01

246

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

247

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

248

Synchrotron X-ray Powder Diffraction and Absorption Spectroscopy in Pulsed Magnetic Fields with Milliseconds Duration  

SciTech Connect

X-ray Powder Diffraction and X-ray Absorption Spectroscopy experiments (WAS) and X-ray magnetic circular dichroism (XMCD) experiments were carried out at the ESRF DUBBLE beam line (BM26) and at the energy dispersive beam line (ID24), respectively. A mobile pulse generator, developed at the LNCMP, delivered 110kJ to the load coil, which was sufficient to generate peak fields of 30T with a rise time of about 5 ms. A liquid He flow cryostat allowed us to vary the sample temperature accurately between 4.2K and 300K.Powder diffraction patterns of TbVO4 were recorded in a broad temperature range using 21 keV monochromatic X-rays and using an on-line image plate detector. We observed the suppression of the Jahn-Teller structural distortion in TbVO4 due to the high magnetic pulsed field.XAS spectra could be measured and finite XMCD signals, directly proportional to the magnetic moment on the Gd absorber atom, were measured in thin Gd foils. Thanks to its element and orbital selectivity, XMCD proofs to be very useful in probing the magnetic properties and due to the strong brilliance of the synchrotron beam, the signals can be measured even in the ms range.

Vanacken, J. [LNCMP, 143, avenue de Rangueil BP 14245, F31432 Toulouse (France); Pulsveldengroep, INPAC, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Detlefs, C.; Mathon, O.; Dominguez, M.-C. [ESRF, BP 220, F-38043 Grenoble (France); Frings, P.; Duc, F.; Nardone, M.; Billette, J.; Zitouni, A.; Rikken, G. [LNCMP, 143, avenue de Rangueil BP 14245, F31432 Toulouse (France); Lorenzo, J. E. [Laboratoire de Cristallographie, CNRS, B.P.166X, F-38043 Grenoble (France); Herczeg, J.; Moshchalkov, V. V. [Pulsveldengroep, INPAC, Celestijnenlaan 200 D, B-3001 Leuven (Belgium); Bras, W. [DUBBLE CRG at ESRF, BP 220, F-38043 Grenoble (France)

2007-03-30

249

Optical spectroscopy of X-ray source 1RXS J194211.9+255552  

NASA Astrophysics Data System (ADS)

Using the 1.5m "Cassini" telescope of the Astronomical Observatory of Bologna in Loiano (Italy) equipped with the BFOSC instrument, we spectroscopically observed the putative optical counterpart (ATel #3818) of the transient X-ray source 1RXS J194211.9+255552 detected with INTEGRAL/JEM-X (ATel #3816). Observations were acquired starting at 22:47 UT of 16 June 2012, for a total exposure time of 5400 s.

Masetti, N.; Landi, R.; Parisi, P.; Bazzano, A.; Bird, A. J.

2012-06-01

250

X-ray laser spectroscopy of highly charged ions at FLASH  

NASA Astrophysics Data System (ADS)

Laser spectroscopy, widely applied in physics and chemistry, is extended into the soft x-ray region for the first time. Resonant fluorescence excitation of highly charged ions (HCIs) by soft x-ray free-electron lasers (FELs) shows here the potential for unprecedented precision on photonic transitions hitherto out of reach. The novel experiments combine an electron beam ion trap (EBIT) with the Free-electron LASer at Hamburg (FLASH) to measure resonant fluorescence by trapped HCIs as a function of the laser's wavelength. The present experiments have already reached the performance of conventional soft and hard x-ray spectroscopy. We present the results obtained for three fundamental and theoretically challenging transitions in Li-like ions, namely 1s22s 2S1/2-1s22p 2P1/2 in Fe23+ at 48.6 eV, in Cu26+ at 55.2 eV and 1s22s 2S1/2-1s22p 2P3/2 in Fe23+ at 65.3 eV. The latter demonstrates laser spectroscopy of multiply or HCIs at more than one order of magnitude higher energies than hitherto reported. Resolving power leading to relative precision up to 6 parts-per-million points to the possibility of providing an atomic absolute wavelength standard in this spectral region, which is still lacking.

Epp, S. W.; Crespo López-Urrutia, J. R.; Simon, M. C.; Baumann, T.; Brenner, G.; Ginzel, R.; Guerassimova, N.; Mäckel, V.; Mokler, P. H.; Schmitt, B. L.; Tawara, H.; Ullrich, J.

2010-10-01

251

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

PubMed

For electronic excitations in the ultraviolet and visible range of the electromagnetic spectrum, the intensities are usually calculated within the dipole approximation, which assumes that the oscillating electric field is constant over the length scale of the transition. For the short wavelengths used in hard X-ray spectroscopy, the dipole approximation may not be adequate. In particular, for metal K-edge X-ray absorption spectroscopy (XAS), it becomes necessary to include higher-order contributions. In quantum-chemical approaches to X-ray spectroscopy, these so-called quadrupole intensities have so far been calculated by including contributions depending on the square of the electric-quadrupole and magnetic-dipole transition moments. However, the resulting quadrupole intensities depend on the choice of the origin of the coordinate system. Here, we show that for obtaining an origin-independent theory, one has to include all contributions that are of the same order in the wave vector consistently. This leads to two additional contributions depending on products of the electric-dipole and electric-octupole and of the electric-dipole and magnetic-quadrupole transition moments, respectively. We have implemented such an origin-independent calculation of quadrupole intensities in XAS within time-dependent density-functional theory, and demonstrate its usefulness for the calculation of metal and ligand K-edge XAS spectra of transition metal complexes. PMID:23205980

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

2012-11-28

252

STIS UV spectroscopy of a bright nova during its super soft X-ray phase  

NASA Astrophysics Data System (ADS)

We propose ToO observations of one bright nova in outburst using the STIS echelle to obtain ultraviolet spectroscopy while the source is X-ray luminous. UV spectroscopy enables determination of ejecta physical properties, including the elemental abundances, ejecta mass, and structure. This information provides insight into the role of novae in the isotopic enrichment of the Interstellar Medium, pre-solar grain abundances, details on the mass and composition of the underlying white dwarf, and constraints on hydrodynamic modeling of the outburst. UV data are key to these analyses, providing the only opportunity to observe strong carbon lines in these objects as well as direct measures of the interstellar reddening. With slit spectroscopy from ~1100-3100 Angstroms, HST is currently the only facility that can provide these data. The data will complement our existing ground based optical, infrared and radio and Swift X-ray nova ToO programs providing continous spectral information from X-ray to the radio.

Schwarz, Gregory

2011-10-01

253

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

SciTech Connect

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

Szlachetko, J. [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Institute of Physics, Jan Kochanowski University, 25-406 Kielce (Poland); Nachtegaal, M.; Boni, E. de; Willimann, M.; Safonova, O.; Sa, J.; Smolentsev, G.; Szlachetko, M.; Bergamaschi, A.; Schmitt, B.; David, C.; Luecke, A. [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Bokhoven, J. A. van [Paul Scherrer Institut, 5232 Villigen PSI (Switzerland); Institute for Chemical and Bioengineering, ETH Zurich, 8093 Zuerich (Switzerland); Dousse, J.-Cl.; Hoszowska, J.; Kayser, Y. [Department of Physics, University of Fribourg, 1700 Fribourg (Switzerland); Jagodzinski, P. [University of Technology, Kielce (Poland)

2012-10-15

254

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

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

255

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

256

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

257

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

258

The high-energy celestial X-ray instrument on board OSO-8  

NASA Technical Reports Server (NTRS)

The 20 keV-3 MeV celestial X-ray detector on the OSO-8 is described. The primary objectives of this instrument are to measure the energy spectrum of cosmic X-ray sources above 20 keV and to search for time variations, both periodic and irregular, in the intensity of the sources detected. The detector consists of two optically isolated central crystals shielded by a large, active collimator. The sensitive area is 27.5 sq cm and the field-of-view is 5 deg FWHM. The instrument is mounted in the wheel section of OSO-8 with the axis of its field of view offset by 5 deg from the negative spin axis of the wheel. The minimum detectable intensity of a point source which is brought to within 5 deg of the negative spin axis for greater than one day is about 10 to the minus fifth power photons/sq cm-sec at 100 keV.

Dennis, B. R.; Frost, K. J.; Lencho, R. J.; Orwig, L. E.

1977-01-01

259

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

NASA Astrophysics Data System (ADS)

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.

1999-09-01

260

The photochemical formation of a Titan haze analog. Structural analysis by X-ray photoelectron and infrared spectroscopy  

E-print Network

The photochemical formation of a Titan haze analog. Structural analysis by X-ray photoelectron a Titan haze analog as a solid product. X-ray photoelectron spectroscopy (XPS) gave a composition of 93. The polymeric product had a C:N ratio of 17.6, which is significantly greater than that for Titan haze analogs

Ferris, James P.

261

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

NASA Astrophysics Data System (ADS)

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

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

2009-05-01

262

The electronic structure of polyaniline and doped phases studied by soft X-ray absorption and emission spectroscopies  

E-print Network

The electronic structure of the conjugated polymer, polyaniline, has been studied by resonant and nonresonant X-ray emission spectroscopy using synchrotron radiation for the excitation. The measurements were made on polyaniline and a few doped (protonated) phases for both the carbon and nitrogen contents. The resonant X-ray emission spectra show depletion of the {\\pi} electron bands due to the selective excitation which enhances the effect of symmetry selection rules. The valence band structures in the X-ray emission spectra attributed to the {\\pi} bands show unambiguous changes of the electronic structure upon protonation. By comparing to X-ray absorption measurements, the chemical bonding and electronic configuration is characterized.

Magnuson, M; Butorin, S M; Agui, A; Såthe, C; Nordgren, J; Monkman, A P; 10.1063/1.479238

2012-01-01

263

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

264

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

SciTech Connect

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

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

1998-12-31

265

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

266

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

267

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

PubMed Central

Several nonlinear spectroscopy experiments which employ broadband x-ray pulses to probe the coupling between localized core and delocalized valence excitation are simulated for the amino acid cysteine at the K-edges of oxygen and nitrogen and the K- and L-edges of sulfur. We focus on two-dimensional (2D) and 3D signals generated by two- and three-pulse stimulated x-ray Raman spectroscopy (SXRS) with frequency-dispersed probe. We show how the four-pulse x-ray signals \\documentclass[12pt]{minimal}\\begin{document}${\\bm k}_\\mathrm{I} =-{\\bm k} _1+{\\bm k} _2+{\\bm k} _3$\\end{document}kI=?k1+k2+k3 and \\documentclass[12pt]{minimal}\\begin{document}${\\bm k}_\\mathrm{II} ={\\bm k} _1-{\\bm k} _2+{\\bm k} _3$\\end{document}k II =k1?k2+k3 can give new 3D insight into the SXRS signals. The coupling between valence- and core-excited states can be visualized in three-dimensional plots, revealing the origin of the polarizability that controls the simpler pump-probe SXRS signals. PMID:24981531

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

2013-01-01

268

Surface Arsenic Speciation of a Drinking-Water Treatment Residual Using X-Ray Absorption Spectroscopy  

SciTech Connect

Drinking-water treatment residuals (WTRs) present a low-cost geosorbent for As-contaminated waters and soils. Previous work has demonstrated the high affinity of WTRs for As, but data pertaining to the stability of sorbed As is missing. Sorption/desorption and X-ray absorption spectroscopy (XAS), both XANES (X-ray absorption near edge structure) and EXAFS (extended X-ray absorption fine structure) studies, were combined to determine the stability of As sorbed by an Fe-based WTR. Arsenic(V) and As(III) sorption kinetics were biphasic in nature, sorbing <90% of the initial added As (15,000 mg kg{sup -1}) after 48 h of reaction. Subsequent desorption experiments with a high P load (7500 mg kg{sup -1}) showed negligible As desorption for both As species, approximately <3.5% of sorbed As; the small amount of desorbed As was attributed to the abundance of sorption sites. XANES data showed that sorption kinetics for either As(III) or As(V) initially added to solution had no effect on the sorbed As oxidation state. EXAFS spectroscopy suggested that As added either as As(III) or as As(V) formed inner-sphere mononuclear, bidentate complexes, suggesting the stability of the sorbed As, which was further corroborated by the minimum As desorption from the Fe-WTR.

Makris, K.C.; Sarkar, D.; Parsons, J.G.; Datta, R.; Gardea-Torresdey, J.L.

2009-06-03

269

Study of exploding Al wire plasmas using X-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy is a powerful diagnostic technique useful for determining the charge state, temperature and density of plasmas under a wide range of conditions and situations. Our particular interest was the study of the core-corona system generated in electrically exploded wires and wire array Z-pinches. Two wide-bandwidth spectrographs with flat and concave cylindrically bent KAP crystals, and high-resolution spectrographs with spherically bent quartz crystals have been used on the XP and COBRA pulsers at Cornell University. The hybrid X-pinch was used as the continuum x-ray source in the photon energy range of interest for absorption spectroscopy with exploding Al wire experiments. This source is capable of producing broadband continuum x-ray pulses with micron source size and 100 ps duration. Absorption spectra of single exploded Al wires and 2 - 4 wire arrays were recorded with high spatial resolution. The parameters of the dense wire core plasmas and the ablating plasma streams were estimated under different experimental conditions. New spectral features in absorption spectra were observed.

Pikuz, Sergey A.; Shelkovenko, Tatiana A.; Hoyt, Cad L.; Cahill, Adam D.; Hammer, David A.

2012-10-01

270

X-ray absorption spectroscopy of cuprous-thiolate clusters in proteins and model systems  

SciTech Connect

Cuprous-thiolate multimetallic clusters exist in a range of different biological molecules for which no structural information exists from X-ray crystallography. Spectroscopic tools such as X-ray absorption spectroscopy have provided the major structural insights into this family of biological molecules. Recent nuclear magnetic resonance data on silver-substituted metallothionein, thought to be analogous with the copper proteins, have suggested the presence of digonal coordination. In order to test this in the copper case, we have examined a series of structurally characterized cuprous-thiolate model compounds, containing different proportions of digonal and trigonal copper sites, using copper K-edge X-ray absorption spectroscopy. The edge spectra, which have been previously used as a probe for the average copper coordination environment in proteins, show little variation between the models, indicating that these are not useful as a probe of coordination environment in the case of cuprous-thiolate clusters (as opposed to isolated metal sites). We show that systematic trends in the average Cu-S bond length from EXAFS curve-fitting analysis can be used to obtain an estimate of the fraction of digonal and trigonal copper sites. This correlation is applied to a series of different proteins containing cuprous-thiolate clusters which are found to contain significant fractions of digonal copper. 41 refs., 7 figs., 3 tabs.

Pickering, I.J.; George, G.N. (Stanford Univ., CA (United States)); Dameron, C.T.; Kurz, B.; Winge, D.R. (Univ. of Utah, Salt Lake City, UT (United States)); Dance, I.G. (Univ. of New South Wales, Kensington (Australia))

1993-10-20

271

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

PubMed

The geochemical behavior and speciation of arsenic (As) in paddy soils is strongly controlled by soil redox conditions and the sequestration by soil iron oxyhydroxides. Hence, the effects of iron oxide reductive dissolution on the adsorption, transformation and precipitation of As(III) and As(V) in soils were investigated using batch experiments and synchrotron based techniques to gain a deeper understanding at both macroscopic and microscopic scales. The results of batch sorption experiments revealed that the sorption capacity of As(V) on anoxic soil was much higher than that on control soil. Synchrotron based X-ray fluorescence (?-XRF) mapping studies indicated that As was heterogeneously distributed and was mainly associated with iron in the soil. X-ray absorption near edge structure (XANES), micro-X-ray absorption near edge structure (?-XANES) and X-ray photoelectron spectroscopy (XPS) analyses revealed that the primary speciation of As in the soil is As(V). These results further suggested that, when As(V) was introduced into the anoxic soil, the rapid coprecipitation of As(V) with ferric/ferrous ion prevented its reduction to As(III), and was the main mechanism controlling the immobilization of As. This research could improve the current understanding of soil As chemistry in paddy and wetland soils. PMID:25064258

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

2014-08-30

272

Detection, identification and mapping of iron anomalies in brain tissue using X-ray absorption spectroscopy  

SciTech Connect

This work describes a novel method for the detection, identification and mapping of anomalous iron compounds in mammalian brain tissue using X-ray absorption spectroscopy. We have located and identified individual iron anomalies in an avian tissue model associated with ferritin, biogenic magnetite and haemoglobin with a pixel resolution of less than 5 {micro}m. This technique represents a breakthrough in the study of both intra- and extra-cellular iron compounds in brain tissue. The potential for high-resolution iron mapping using microfocused X-ray beams has direct application to investigations of the location and structural form of iron compounds associated with human neurodegenerative disorders - a problem which has vexed researchers for 50 years.

Mikhaylova, A.; Davidson, M.; Toastmann, H.; Channell, J.E.T.; Guyodo, Y.; Batich, C.; Dobson, J. (Keele); (Florida); (IRM)

2008-06-16

273

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

274

Gold nanotags for combined multi-colored Raman spectroscopy and x-ray computed tomography  

NASA Astrophysics Data System (ADS)

Multi-color gold-nanoparticle-based tags (nanotags) are synthesized for combined surface-enhanced Raman spectroscopy (SERS) and x-ray computed tomography (CT). The nanotags are synthesized with quasi-spherical gold nanoparticles encoded with a reporter dye (color), each with a unique Raman spectrum. A library of nanotags with six different colors were synthesized for a range of gold nanoparticle sizes and an optimum size has been established to yield the largest SERS intensity and x-ray attenuation that is higher than the iodinated CT contrast agents used in clinics. Proof-of-principle in vivo imaging results with nanotags are presented that, for the first time, demonstrates the combined in vivo dual modality imaging capability of SERS and CT with a single nanoparticle probe.

Xiao, Ming; Nyagilo, James; Arora, Veera; Kulkarni, Padmakar; Xu, Dongsheng; Sun, Xiankai; Davé, Digant P.

2010-01-01

275

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

276

In situ x-ray photoelectron spectroscopy for electrochemical reactions in ordinary solvents  

SciTech Connect

In situ electrochemical X-ray photoelectron spectroscopy (XPS) apparatus, which allows XPS at solid/liquid interfaces under potential control, was constructed utilizing a microcell with an ultra-thin Si membrane, which separates vacuum and a solution. Hard X-rays from a synchrotron source penetrate into the Si membrane surface exposed to the solution. Electrons emitted at the Si/solution interface can pass through the membrane and be analyzed by an analyzer placed in vacuum. Its operation was demonstrated for potential-induced Si oxide growth in water. Effect of potential and time on the thickness of Si and Si oxide layers was quantitatively determined at sub-nanometer resolution.

Masuda, Takuya [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012 (Japan); Yoshikawa, Hideki; Kobata, Masaaki; Kobayashi, Keisuke [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), Sayo, Hyogo 679-5148 (Japan)] [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science (NIMS), Sayo, Hyogo 679-5148 (Japan); Noguchi, Hidenori [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); PRESTO, Japan Science and Technology Agency (JST), 4-1-8 Honcho, Kawaguchi, Saitama 333-0012 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan); Kawasaki, Tadahiro [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603 (Japan)] [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa, Nagoya 464-8603 (Japan); Uosaki, Kohei [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan) [Global Research Center for Environment and Energy Based on Nanomaterials Science (GREEN), National Institute for Materials Science (NIMS), Tsukuba 305-0044 (Japan); Graduate School of Chemical Sciences and Engineering, Hokkaido University, Sapporo, Hokkaido 060-0810 (Japan); International Center for Materials Nanoarchitectonics (WPI-MANA), National Institute for Materials Science (NIMS), Tsukuba, Ibaraki 305-0044 (Japan)

2013-09-09

277

Soft x-ray spectroscopy undulator beamline at the Advanced Photon Source  

SciTech Connect

Construction of the high-resolution soft x ray spectroscopy undulator beamline, 2ID-C, at the Advanced Photon Source (APS) has been completed. The beamline, one of two soft x ray beamlines at the APS, will cover the photon energy range from 500 to 3,000 eV, with a maximum resolving power between 7,000 and 14,000. The optical design is based on a spherical grating monochromator (SGM) giving both high resolution and high flux throughput. Photon flux is calculated to be approximately 10{sup 12}--10{sup 13} photons per second with a beam size of approximately 1 x 1 mm{sup 2} at the sample.

Randall, K.J.; Xu, Z.; Moore, J.F.; Gluskin, E.

1997-09-01

278

Cryogenic detector development at LLNL: ultraviolet x-ray, gamma-ray and biomolecule spectroscopy  

SciTech Connect

We are developing low-temperature detectors for optical, ultraviolet, X-ray, and gamma-ray spectroscopy, and for biomolecular mass spectrometry. We present development work on these detectors and materials analysis and biomolecular mass spectrometry. We have measured thin-film Nb/Al/Al2O3/AlNb superconducting tunnel junction (STJ) X-ray detectors in the 0.2 to 1 keV band with a range of different junction sizes and aluminum film thicknesses. In one case, we have achieved the statistical limit to the energy resolution of 13 eV FWHM at 227 eV with an output count rate of 20,600 cts/s.

Labov, S.E.; Frank, M.; le Grand, J.B. [and others

1997-08-12

279

Coherent stimulated x-ray Raman spectroscopy: Attosecond extension of resonant inelastic x-ray Raman scattering  

SciTech Connect

Spontaneous and stimulated resonant inelastic x-ray Raman-scattering signals are calculated using the Keldysh-Schwinger closed-time path loop and expressed as overlaps of doorway and window electron-hole wave packets. These are recast in terms of the one-particle Green's functions and expansion coefficients of configuration-interaction singles for valence excitations, which can be obtained from standard electronic structure codes. Calculation for many-body states of ground and core-excited systems is avoided.

Harbola, Upendra [Department of Chemistry and Biochemistry, University of California-San Diego, San Diego, California 92093-0340 (United States); Mukamel, Shaul [Department of Chemistry, University of California-Irvine, Irvine, California 92697-2025 (United States)

2009-02-15

280

Focal plane instrumentation for the Wide-Field X-ray Telescope  

E-print Network

The three X-ray imaging focal planes of the Wide-Field X-ray Telescope (WFXT) Mission will each have a field of view up to 1 degree square, pixel pitch smaller than 1 arcsec, excellent X-ray detection efficiency and spectral ...

Bautz, Marshall W.

281

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

282

The Chandra Multi-wavelength Project: Optical Spectroscopy and the Broadband Spectral Energy Distributions of X-ray selected AGNs  

NASA Astrophysics Data System (ADS)

From optical spectroscopy of X-ray serendipitous sources observed as part of ChaMP, we present redshifts and classifications for a total of 1569 Chandra sources from our targeted spectroscopic follow up. We have compiled extensive photometry from X-ray to radio bands. Together with our spectroscopic information, this enables us to derive detailed SEDs for our extragalactic sources. While ~58% of X-ray Seyferts require a starburst event to fit observed photometry only 26% of the X-ray QSO population appear to have some kind of star formation contribution. In addition, we observe a rapid drop of the percentage of starburst contribution as X-ray luminosity increases. This is consistent with the quenching of star formation by powerful QSOs, as predicted by the merger model, or with a time lag between the peak of star formation and QSO activity. We have tested the hypothesis that there should be a strong connection between X-ray obscuration and star formation but we do not find any association between X-ray column density and star formation rate both in the general population or the star-forming X-ray Seyferts. Our large spectroscopic compilation also allows us to report here the identification of the largest high-redshift X-ray selected sample a total of 78 z>3 sources.

Trichas, Markos; Green, P.; Silverman, J.; Aldcroft, T.; Wilkes, B.; Constantin, A.; Haggard, D.; Kim, DW

2012-09-01

283

The amorphous Zn biomineralization at Naracauli stream, Sardinia: electron microscopy and X-ray absorption spectroscopy.  

PubMed

An amorphous Zn biomineralization ("white mud"), occurring at Naracauli stream, Sardinia, in association with cyanobacteria Leptolyngbya frigida and diatoms, was investigated by electron microscopy and X-ray absorption spectroscopy. Preliminary diffraction analysis shows that the precipitate sampled on Naracauli stream bed is mainly amorphous, with some peaks ascribable to quartz and phyllosilicates, plus few minor unattributed peaks. Scanning electron microscopy analysis shows that the white mud, precipitated in association with a seasonal biofilm, is made of sheaths rich in Zn, Si, and O, plus filaments likely made of organic matter. Transmission electron microscopy analysis shows that the sheaths are made of smaller units having a size in the range between 100 and 200 nm. X-ray absorption near-edge structure and extended X-ray absorption fine structure data collected at the Zn K-edge indicate that the biomineral has a local structure similar to hemimorphite, a zinc sorosilicate. The differences of this biomineral with respect to the hydrozincite biomineralization documented about 3 km upstream in the same Naracauli stream may be related to either variations in the physicochemical parameters and/or different metabolic behavior of the involved biota. PMID:23832800

Medas, D; Lattanzi, P; Podda, F; Meneghini, C; Trapananti, A; Sprocati, A; Casu, M A; Musu, E; De Giudici, G

2014-06-01

284

X-ray spectroscopy for chemical and energy sciences: the case of heterogeneous catalysis.  

PubMed

Heterogeneous catalysis is the enabling technology for much of the current and future processes relevant for energy conversion and chemicals synthesis. The development of new materials and processes is greatly helped by the understanding of the catalytic process at the molecular level on the macro/micro-kinetic time scale and on that of the actual bond breaking and bond making. The performance of heterogeneous catalysts is inherently the average over the ensemble of active sites. Much development aims at unravelling the structure of the active site; however, in general, these methods yield the ensemble-average structure. A benefit of X-ray-based methods is the large penetration depth of the X-rays, enabling in situ and operando measurements. The potential of X-ray absorption and emission spectroscopy methods (XANES, EXAFS, HERFD, RIXS and HEROS) to directly measure the structure of the catalytically active site at the single nanoparticle level using nanometer beams at diffraction-limited storage ring sources is highlighted. The use of pump-probe schemes coupled with single-shot experiments will extend the time range from the micro/macro-kinetic time domain to the time scale of bond breaking and making. PMID:25177997

Frenkel, Anatoly I; van Bokhoven, Jeroen A

2014-09-01

285

Laboratory x-ray spectroscopy experiments in support of NASA`s x-ray satellite missions  

SciTech Connect

With support from NASA, we are performing a series of laboratory astrophysics investigations designed to address fundamental uncertainties in basic atomic physics processes relevant to the interpretation of discrete X-ray spectra of cosmic plasmas. Moderate resolution spectra acquired by the ASCA Observatory already demonstrate the inadequacy of currently available spectral modelling codes for this wavelength band. With the upcoming launches of AXAF, XMM, ASTRO E, and Spektrum Roentgen-Gamma, the demand for significant advances in this field will increase dramatically. Our program is based on the exploitation of the Electron Beam Ion Trap facility at the Lawrence Livermore National Laboratory, and a unique set of spectrometers and experimental techiques specifically developed for this purpose. Recent experiments have been devoted to definitive measurements of line emissivities for iron L-shell ions in optically thin, collisional plasmas.

Kahn, S. M., Columbia University

1998-05-22

286

Characterization of Mo additions in iron-based Fischer Tropsch catalysts using X-ray absorption spectroscopy and X-ray diffraction  

NASA Astrophysics Data System (ADS)

An iron-based Fischer-Tropsch catalyst with a low concentration of molybdenum (90Fe/10Mo/5Cu/17Si) used as a promoter was characterized by X-ray absorption spectroscopy (XAS) and X-ray diffractometry (XRD). The catalyst was prepared using coprecipitation, pretreated in CO, then one sample passivated and one calcined. The XRD data show that after CO pretreatment the calcined and passivated catalysts are almost amorphous with respect to Fe 2O 3 with nanoparticle size of 10 and 100 Å for Fe 3C (only present in the passivated sample). Least squares fitting of the XANES region show that the calcined and passivated samples were similar in the bulk and surface structures, with the calcined samples completely oxidized. As expected, K and L III edges Mo-XANES shows only small molybdenum carbide formation compared to iron carbide.

Campos, A.; Spivey, J. J.; Roy, A.; Lohitharn, N.; Goodwin, J.; Lotero, E.; Lamb, H.

2007-11-01

287

Study of hard disk and slider surfaces using X-ray photoemission electron microscopy and near-edge X-ray absorption fine structure spectroscopy  

SciTech Connect

X-ray Photo Emission Electron Microscopy (X-PEEM) and Near Edge X-ray Absorption Fine Structure (NEXAFS) spectroscopy were applied to study the properties of amorphous hard carbon overcoats on disks and sliders, and the properties of the lubricant. The modification of lubricants after performing thermal desorption studies was measured by NEXAFS, and the results are compared to the thermal desorption data. The study of lubricant degradation in wear tracks is described. Sliders were investigated before and after wear test, and the modification of the slider coating as well as the transfer of lubricant to the slider was studied. The studies show that the lubricant is altered chemically during the wear. Fluorine is removed and carboxyl groups are formed.

Anders, S.; Stammler, T. [Lawrence Berkeley National lab., CA (United States). Advanced Light Source Div.; Bhatia, C.S. [SSD/IBM, San Jose, CA (United States); Stoehr, J. [IBM Research Div., San Jose, CA (United States). Almaden Research Center; Fong, W.; Chen, C.Y.; Bogy, D.B. [Univ. of California, Berkeley, CA (United States)

1998-04-01

288

X-ray photoelectron spectroscopy analysis of organic materials irradiated with gas cluster ion beam  

SciTech Connect

Irradiation effect of gas cluster ion beams (GCIB) on organic materials were studied with X-ray photoelectron spectroscopy by comparison to that with Ar-monomer ions. In the case of polyimide, the intensity of both N-C = O and -C-O- bond decreased with 500 eV Ar monomer ion irradiation. On the other hand, there was no significant change in the XPS spectra after Ar-GCIB irradiation. From the size-selected GCIB irradiation study, the damages in polyimide decreased with increasing the cluster size owing to the reduction of energy per atoms.

Nakagiri, Motohiro; Toyoda, Noriaki; Yamada, Isao [Incubation center, Graduate school of engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo, 671-2280 (Japan)

2011-01-07

289

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

Microsoft Academic Search

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

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

2009-01-01

290

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

291

Composition of RF-sputtered refractory compounds determined by X-ray photoelectron spectroscopy  

NASA Technical Reports Server (NTRS)

RF-sputtered coatings of CrB2, MoSi2, Mo2C, TiC, and MoS2 were examined by X-ray photoelectron spectroscopy (XPS). Data on stoichiometry, impurity content, and chemical bonding were obtained. The influences of sputtering target history, deposition time, RF power level, and substrate bias were studied. Significant deviations from stoichiometry and high oxide levels were related to target outgassing. The effect of substrate bias depended on the particular coating material studied.

Wheeler, D. R.; Brainard, W. A.

1978-01-01

292

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

293

Structure of molybdenum-phosphate glasses by X-ray photoelectron spectroscopy (XPS)  

Microsoft Academic Search

Highly-concentrated molybdenum-phosphate glasses with analyzed compositions of Mo greater than 0.65 have been studied by X-ray photoelectron spectroscopy (XPS) and magnetization measurements. 1 eV shifts in the binding energies of P2p, P2s, Mo3d, and Mo3p from their respective values in P2O5 and MoO3 can be accounted for by changes in the next nearest neighbor environment of the P and Mo

G. D. Khattak; M. A. Salim; A. S. Al-Harthi; David J. Thompson; L. E. Wenger

1997-01-01

294

Band offsets of films grown on Ge substrates by X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

The band alignments of high-k Er2O3 films grown on Ge substrates by molecular beam epitaxy are determined by X-ray photoelectron spectroscopy. The valence-band and the conduction-band offsets of Er2O3 to Ge are found to be and , respectively. The energy gap of Er2O3 is as determined by the optical spectrophotometry. From the band offset viewpoint, the above results indicate that Er2O3 could be a promising candidate for high-k gate dielectrics on Ge substrate.

Ji, Ting; Peng, Lining; Fang, Zebo; Cui, Yanxia; Hao, Yuying

2014-06-01

295

High resolution and symmetry resolved core-level spectroscopy using soft x-ray undulator (invited)  

SciTech Connect

The performance of a soft x-ray undulator beamline equipped with a 10 m grazing incidence monochromator is described. Several experimental results are presented to exemplify the good performance. The decomposition of photoabsorption spectra of CO and O{sub 2} into their component molecular symmetries has been achieved by our new experimental technique of angle-resolved photoion spectroscopy. Two Rydberg series converging to the K-shell ionization limits of O{sub 2} have been revealed in a high resolution spectrum.

Yagishita, A.; Shigemasa, E. (Photon Factory, National Laboratory for High Energy Physics, Oho 1-1, Tsukuba-shi, Ibaraki-ken 305 (Japan))

1992-01-01

296

X-ray Absorption spectroscopy and electronic structure calculation of DyScO3  

Microsoft Academic Search

Dysprosium scandate (DyScO3) is of interest for its potential as a substrate for thin film growth of various materials such as EuTiO3, SrTiO3 BaTiO3 and LaSrMnTiO3 particularly because it creates biaxial strain due to mismatched lattice constant with those materials affecting their properties. We have used X-ray Absorption Spectroscopy to determine the electronic structure of DyScO3. The M4,5 edges of

Harshawardhan Bhatkar; B. Anderson; M. Finsterbusch; P. Rugheimer; Y. U. Idzerda

2010-01-01

297

Contact-free pyroelectric measurements using x-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

Non-contact pyroelectricity measurements based on x-ray photoelectron spectroscopy (XPS) are presented. Applied to Lithium Tantalate crystals, we demonstrate how the XPS-derived surface potential provides a simple probe of the desired property, free of all top-contact related difficulties. In particular, the increase in Lithium Tantalate spontaneous polarization under cooling, an experimentally challenging feature, is evaluated. We further inspect the roll of surface contaminants and the control over trapped surface charge in the XPS vacuum environment. Our approach can be extended to other non-contact probes, as well as to measuring additional electrical properties, such as piezoelectricity and ferroelectricity.

Ehre, D.; Cohen, H.

2013-07-01

298

X-ray photoelectron spectroscopy of KrF laser-irradiated polycarbonate films  

NASA Astrophysics Data System (ADS)

Spun films of polycarbonate were photoablated in air at 248 nm. The etch and incubation data have a superlinear dependence on the laser fluence. The surface compositional changes were analysed by X-ray photoelectron spectroscopy (XPS). As evidenced by the decrease of the O/C ratio, photoablation is inferred as distinct from the low-intensity photooxidative degradation. A direct correlation is observed between the XPS and incubation data and the ablation seems to occur by chain scission at the C?O bond, the fully incubated surface being an average of monomeric composition.

Lemoine, P.; Cazzini, K.; McGovern, I. T.; Blau, W. J.; Bätz, P.; Ziegler, C.; Göpel, W.

1994-04-01

299

X-Ray Absorption Spectroscopy of Cuprous-Thiolate Clusters in Saccharomyces Cerevisiae Metallothionein  

SciTech Connect

Copper (Cu) metallothioneins are cuprous-thiolate proteins that contain multimetallic clusters, and are thought to have dual functions of Cu storage and Cu detoxification. We have used a combination of X-ray absorption spectroscopy (XAS) and density-functional theory (DFT) to investigate the nature of Cu binding to Saccharomyces cerevisiae metallothionein. We found that the XAS of metallothionein prepared, containing a full complement of Cu, was quantitatively consistent with the crystal structure, and that reconstitution of the apo-metallothionein with stoichiometric Cu results in the formation of a tetracopper cluster, indicating cooperative binding of the Cu ions by the metallothionein.

Zhang, L.; Pickering, I.J.; Winge, D.R.; George, G.N.

2009-05-28

300

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

301

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

SciTech Connect

A diagnostic currently being used for ultrashort pulse laser matter interactions at the Lawrence Livemore National Laboratory is presented. Two cylindrical curved crystals are used as collection optics and diffractive elements in the von Hamos geometry. The dispersed x rays are focused onto the slit of an ultrafast x-ray streak camera. The small nature of the streak camera allows the diagnostic to be positioned close to the target, maximizing the solid angle. Using the geometric layout, the spectral resolution is estimated at E/{delta}E{approx}1000.

Shepherd, Ronnie; Audebert, Patrick; Booth, Rex; Young, Bruce; Bonlie, Jim; Nelson, Don; Shiromizu, Steve; Price, Dwight; Norman, Douglas; Dunn, Jim; Widmann, Klaus; Springer, Paul [Physics and Applied Technologies, Lawrence Livermore National Laboratory, M.S. L-43, Livermore, California 94550 (United States); Laboratoire pour l'Utilisation des Lasers Intenses, UMR No 7605 CNRS, CEA, Ecole Polytechnique, Univ. Paris IV, 91128, Palaiseau (France); Physics and Applied Technologies, Lawrence Livermore National Laboratory, M.S. L-43, Livermore, California 94550 (United States)

2004-10-01

302

Measurement of c-axis angular orientation in calcite (CaCO3) nanocrystals using X-ray absorption spectroscopy  

PubMed Central

We demonstrate that the ability to manipulate the polarization of synchrotron radiation can be exploited to enhance the capabilities of X-ray absorption near-edge structure (XANES) spectroscopy, to include linear dichroism effects. By acquiring spectra at the same photon energies but different polarizations, and using a photoelectron emission spectromicroscope (PEEM), one can quantitatively determine the angular orientation of micro- and nanocrystals with a spatial resolution down to 10 nm. XANES-PEEM instruments are already present at most synchrotrons, hence these methods are readily available. The methods are demonstrated here on geologic calcite (CaCO3) and used to investigate the prismatic layer of a mollusk shell, Pinctada fucata. These XANES-PEEM data reveal multiply oriented nanocrystals within calcite prisms, previously thought to be monocrystalline. The subdivision into multiply oriented nanocrystals, spread by more than 50°, may explain the excellent mechanical properties of the prismatic layer, known for decades but never explained. PMID:21693647

Gilbert, P. U. P. A.; Young, Anthony; Coppersmith, Susan N.

2011-01-01

303

Time Resolved Spectroscopy, High Sensitivity Power Spectrum & a Search for the X-Ray QPO in NGC 5548  

NASA Astrophysics Data System (ADS)

Controversy surrounds the EXOSAT discovery of a QPO (period ~500 s) in NGC 5548 due to the data being plagued by high background and instrumental systematics. If the NGC 5548 QPO is real, the implications for the physics of the X-ray emission mechanism and inner-most disk/black-hole system are enormous. AXAF provides the first opportunity to settle the issue, capable of yielding power spectra with unprecedented sensitivity, pushing the limit on finding new features. Using HETG/ACIS we will also perform time-resolved spectroscopy of the ionized absorption features and Fe-K emission line, search for energy-dependent time lags in the continuum, between the continuum and spectral features, and between the spectral features. These data will provide powerful constraints on models of AGN.

Yaqoob, Tahir

1999-09-01

304

New Optimizations of Microcalorimeter Arrays for High-Resolution Imaging X-ray Spectroscopy  

NASA Astrophysics Data System (ADS)

We propose to continue our successful research program in developing arrays of superconducting transition-edge sensors (TES) for x-ray astrophysics. Our standard 0.3 mm TES pixel achieves better than 2.5-eV resolution, and we now make 32x32 arrays of such pixels. We have also achieved better than 1-eV resolution in smaller pixels, and promising performance in a range of position-sensitive designs. We propose to continue to advance the designs of both the single-pixel and position-sensitive microcalorimeters so that we can produce arrays suitable for several x-ray spectroscopy observatories presently in formulation. We will also investigate various array and pixel optimizations such as would be needed for large arrays for surveys, large- pixel arrays for diffuse soft x-ray measurements, or sub-arrays of fast pixels optimized for neutron-star burst spectroscopy. In addition, we will develop fabrication processes for integrating sub-arrays with very different pixel designs into a monolithic focal-plane array to simplify the design of the focal-plane assembly and make feasible new detector configurations such as the one currently baselined for AXSIO. Through a series of measurements on test devices, we have improved our understanding of the weak-link physics governing the observed resistive transitions in TES detectors. We propose to build on that work and ultimately use the results to improve the immunity of the detector to environmental magnetic fields, as well as its fundamental performance, in each of the targeted optimizations we are developing.

Kilbourne, Caroline

305

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

306

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

307

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

308

Status and perspectives of high-resolution spectroscopy in the soft x-ray range (invited)  

SciTech Connect

The present status in high-resolution photoabsorption and photoemission spectroscopy using synchrotron radiation in the soft x-ray range (40 eV{le}{ital h}{nu}{le}1000 eV) is described. With the SX700/II monochromator, operated by the Freie Universitaet Berlin at the Berliner Elektronenspeicherring fuer Synchrotronstrahlung (BESSY), a resolving power of up to {ge}10 000 has been achieved. A practical feature of this monochromator is given by the fact that excellent energy resolution is achieved with a single 1221-lines/mm grating in the whole soft x-ray range considered. This opens up new opportunities in core-level photoabsorption spectroscopy of atoms, molecules, adsorbed species, and solids. A combination of the SX700/II beam line with a high-resolution electron spectrometer ({Delta}{ital E}{congruent}15 meV) enables resonant photoemission studies of rare-earth materials in the 4{ital d}{r arrow}4{ital f} giant-resonance region with unprecedented resolution and also at the 3{ital d}{r arrow}4{ital f} absorption thresholds. This spectroscopic progress provides new insight into the correlated electronic structure of Ce systems.

Kaindl, G.; Domke, M.; Laubschat, C.; Weschke, E.; Xue, C. (Institut fuer Experimentalphysik, Freie Universitaet Berlin, Arnimallee 14, W-1000 Berlin 33 (Germany))

1992-01-01

309

Dead time and pileup in pulsed parametric X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

Spectroscopy of parametric X-rays (PXR) from pulsed electron sources is usually done with very low electron beam currents in order to avoid dead time losses and pileup problems. This paper presents a method that allows correction of dead time losses and pileup in pulsed X-ray spectroscopy. Such correction is required in order to study the variation of PXR production and linewidth with increased electron beam currents. The method presented here uses the observed integrated count rate in a PXR peak and the total count rate to obtain the dead time and pileup corrected rates. The method also allows treatment of pulse pileup from a first-order reflection to a second-order reflection and can be extended to higher order reflections. Application of the theory to measured data is demonstrated and corrections of up to a factor of four are demonstrated. The method described in this paper can be applied to any pulsed spectrum measurement and is not specific to PXR, which was used here for comparison of the theory to experiments.

Danon, Yaron; Sones, Bryndol; Block, Robert

2004-05-01

310

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

311

Core and valence excitations in resonant X-ray spectroscopy using restricted excitation window time-dependent density functional theory  

PubMed Central

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 \\documentclass[12pt]{minimal}\\begin{document}$\\textrm {L}_{2,3}$\\end{document}L2,3 edges. Comparison of the simulated XANES signals with experiment shows that the restricted window time-dependent density functional theory is more accurate and computationally less expensive than the static exchange method. Simulated RIXS and 1D SXRS signals give some insights into the correlation of different excitations in the molecule. PMID:23181305

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

2012-01-01

312

Atmospheric Electron-induced X-Ray Spectrometer (AEXS) Instrument Development  

NASA Technical Reports Server (NTRS)

Introduction: This paper describes the progress in data acquisition and establishing the observational capability of the AEXS instrument. The AEXS is a miniature instrument[1-4] based on the excitation of characteristic X-Ray Fluorescence (XRF) and luminescence spectra using a focused electron beam which enables nondestructive evaluation of sample surfaces in planetary ambient atmospheres. In situ operation is obtained through the use of a thin electron transmissive membrane to isolate the vacuum of the AEXS source from the outside ambient atmosphere. Thus eliminating the need for a vacuum pumped sample chamber as is common in all laboratory SEM s. The transmitted electrons impinge on the sample exciting XRF spectra from the irradiated spot on in-situ or collected samples with sub-mm to cm-scale spatial resolution at Mars atmospheric pressure. The AEXS system (Fig 1) consists of a high-energy (>10keV) electron gun encapsulated by the isolation membrane, an XRF detection and analyzer system, and a high voltage power supply. The XRF data are analyzed to determine the elemental abundance for the irradiated spots. The approach to demonstrating a proof of concept of the AEXS has been through 1) demonstrating the viability of microfabricated membranes, 2) assembling AEXS setups with increasingly integrated functional components, and 3) simulating the AEXS observational capabilities. The development of the instrument is described in detail in the poster paper[4] at this conference. This paper focuses on describing the progress of the AEXS instrument to acquire XRF data and using commercially available software to analyze the data streams and determine the accuracy, precision and resolution of the analysis compared to the certified elemental abundance.

Urgiles, E.; Wilcox, J. Z.; Toda, R.; Crisp, J.; George, T.

2005-01-01

313

AGN feedback, X-ray imaging, X-ray spectroscopy and thermal state of the gas in cool-core clusters  

NASA Astrophysics Data System (ADS)

Existing X-ray and radio observations provide solid evidence that large amount of mechanical energy is deposited into the gas by a central supermassive black hole. While simple arguments suggest that close to 100% of this energy is dissipated in the cluster core, the route of dissipation strongly depends on the details of the gas microphysics. We discuss constraints on the thermal state of the gas provided by a combination of existing high-angular-resolution data and future high-energy-resolution spectroscopy.

Churazov, Eugene

314

X-ray diffraction and X-ray photoelectron spectroscopy analysis of Cr-doped spinel LiMn 2O 4 for lithium ion batteries  

Microsoft Academic Search

Cr-doped LiMn2O4 spinels were synthesized by a solid-state reaction. X-ray photoelectron spectroscopy (XPS) investigation shows the structural and valence changes of the Cr-doped LixMn2?yCrzO4 spinels with increasing Cr content. A conversion of Cr3+ to Cr6+ is found in the heavy-doped samples at 0.20

Chuan Wu; Feng Wu; Liquan Chen; Xuejie Huang

2002-01-01

315

X-ray photoelectron spectroscopy and positron annihilation spectroscopy analysis of surfactant affected FePt spintronic films  

NASA Astrophysics Data System (ADS)

This paper reports the effects of surfactant Bi atomic diffusion on the microstructure evolution and resulted property manipulation in FePt spintronic films by the quantitative studies of X-ray photoelectron spectroscopy and positron annihilation spectroscopy. The defect density in the FePt layer, which was tunable by varying the thermal treatment temperatures, was found to be remarkably enhanced correlated with the Bi atomic diffusion behavior. The observed defect density evolution substantially favors Fe(Pt) atomic migrations and lowers the energy barrier for atomic ordering transition, resulting in a great improvement of hard magnet property of the films.

Feng, Chun; Li, Xujing; Liu, Fen; Wang, Qiang; Yang, Meiyin; Zhao, Chongjun; Gong, Kui; Zhang, Peng; Wang, Bao-Yi; Cao, Xing-Zhong; Yu, Guanghua

2014-07-01

316

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

317

A study of ancient pottery by means of X-ray fluorescence spectroscopy, multivariate statistics and mineralogical analysis  

Microsoft Academic Search

Energy-dispersive X-ray fluorescence spectroscopy was used to determine the composition of 64 potsherds from the Hellenistic settlement of Orraon, in northwestern Greece. Data classification by principal components analysis revealed four distinct groups of pottery, pointing to different local production practices rather than different provenance. The interpretation of statistical grouping was corroborated by a complementary X-ray diffraction analysis. Compositional and mineralogical

Christina Papachristodoulou; Artemios Oikonomou; Kostas Ioannides; Konstantina Gravani

2006-01-01

318

Unveiling the nature of INTEGRAL objects through optical spectroscopy. VIII. Identification of 44 newly detected hard X-ray sources  

Microsoft Academic Search

Hard X-ray surveys performed by the INTEGRAL satellite have discovered a conspicuous fraction (up to 30%) of unidentified objects among the detected sources. Here we continue our program of identification of these objects by (i) selecting probable optical candidates by means of positional cross-correlation of the INTEGRAL detections with soft X-ray, radio, and\\/or optical archives and (ii) performing optical spectroscopy

N. Masetti; P. Parisi; E. Palazzi; E. Jiménez-Bailón; V. Chavushyan; L. Bassani; A. Bazzano; A. J. Bird; A. J. Dean; P. A. Charles; G. Galaz; R. Landi; A. Malizia; E. Mason; V. A. McBride; D. Minniti; L. Morelli; F. Schiavone; J. B. Stephen; P. Ubertini

2010-01-01

319

Shedding new light on historical metal samples using micro-focused synchrotron X-ray fluorescence and spectroscopyB  

Microsoft Academic Search

Synchrotron-based micro-X-ray fluorescence (micro-XRF) and micro-X-ray absorption spectroscopy (micro-XAS) were used in the present study to obtain spatially resolved micro-scale information on elemental composition, trace element distribution, chemical speciation and oxidation state and\\/or mineral phase distribution within historical iron artefacts dating from the Iron Age to early Medieval Times. Large area two-dimensional trace element distribution maps and oxidation state maps

D. Grolimund; M. Senn; M. Trottmann; M. Janousch; A. M. Scheidegger; M. Marcus

320

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

321

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

322

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

323

Soft X-Ray Microscopy and Spectroscopy at the Molecular Environmental Science Beamline at the Advanced Light Source  

SciTech Connect

We present examples of the application of synchrotron-based spectroscopies and microscopies to environmentally-relevant samples. The experiments were performed at the Molecular Environmental Science beamline (11.0.2) at the Advanced Light Source, Lawrence Berkeley National Laboratory. Examples range from the study of water monolayers on Pt(111) single crystal surfaces using X-ray emission spectroscopy and the examination of alkali halide solution/water vapor interfaces using ambient pressure photoemission spectroscopy, to the investigation of actinides, river-water biofilms, Al-containing colloids and mineral-bacteria suspensions using scanning transmission X-ray spectromicroscopy. The results of our experiments show that spectroscopy and microscopy in the soft X-ray energy range are excellent tools for the investigation of environmentally relevant samples under realistic conditions, i.e. with water or water vapor present at ambient temperature.

Bluhm, Hendrik; Andersson, Klas J.; Araki, Tohru; Benzerara, Karim; Brown, Gordon E.; Dynes, Jay J.; Ghosal, Sutapa; Gilles, Mary K.; Hansen, Hans C.; Hemminger, J. C.; Hitchcock, Adam P.; Ketteler, Guido; Kilcoyne, Arthur L.; Kneedler, Eric M.; Lawrence, John R.; Leppard, Gary G.; Majzlam, Juraj; Mun, B. S.; Myneni, Satish C.; Nilsson, Anders R.; Ogasawara, Hirohito; Ogletree, D. F.; Pecher, Klaus H.; Salmeron, Miquel B.; Shuh, David K.; Tonner, Brian; Tyliszczak, Tolek; Warwick, Tony; Yoon, T. H.

2006-02-01

324

Diagnosing implosions at the national ignition facility with X-ray spectroscopy  

NASA Astrophysics Data System (ADS)

X-ray spectroscopy is used at the National Ignition Facility (NIF) to diagnose plasma conditions in the hot spot and the compressed shell of ignition-scale inertial confinement fusion (ICF) implosions. Ignition of an ICF target depends on the formation of a central hot spot with sufficient temperature and areal density. The concentric spherical layers of current NIF ignition targets consist of a plastic ablator surrounding a thin shell of cryogenic thermonuclear fuel (i.e., hydrogen isotopes), with fuel vapor filling the interior volume. A fraction of the ablator has a Ge dopant to minimize preheat of the ablator closest to the DT ice caused by Au M-band emission from the hohlraum x-ray drive. This paper concentrates on three spectral features of the implosion: Ge He? emission, Ge K? emission, and the Ge K edge. Hydrodynamic instabilities seeded by highmode (50 < l < 200) ablator-surface perturbations on ignition-scale targets can cause mixing of Ge-doped ablator into the interior of the shell at the end of the acceleration phase. As the shell decelerates, it compresses the fuel vapor, forming a hot spot. K-shell line emission from the ionized Ge that has penetrated into the hot spot provides an experimental signature of hot-spot mix. The amount of hot-spot mix mass is estimated from the brightness and spectral line shape of the Ge He? and satellite emission using a detailed atomic physics code. X-ray continuum from the hot spot is attenuated by the compressed shell, and the photoexcitation causes the shell to fluoresce in Ge K? emission. The contrast at the Ge K edge and the brightness of Ge K? emission are used to diagnose the shell areal density. The highlighted spectral features are presented.

Regan, S. P.; Epstein, R.; Hammel, B. A.; Suter, L. J.; Ralph, J.; Scott, H.; Barrios, M. A.; Bradley, D. K.; Callahan, D. A.; Collins, G. W.; Dixit, S. N.; Edwards, M. J.; Farley, D. R.; Glenzer, S. H.; Golovkin, I. E.; Haan, S. W.; Hamza, A.; Hicks, D. G.; Izumi, N.; Kilkenny, J. D.; Kline, J. L.; Kyrala, G. A.; Landen, O. L.; Ma, T.; MacFarlane, J. J.; MacKinnon, A. J.; Mancini, R. C.; Marshall, F. J.; McCrory, R. L.; Meezan, N. B.; Meyerhofer, D. D.; Nikroo, A.; Peterson, K. J.; Sangster, T. C.; Springer, P.; Town, R. P. J.

2012-05-01

325

Characterization of Metalloproteins by High-throughput X-ray Absorption Spectroscopy  

SciTech Connect

High-throughput X-ray absorption spectroscopy was used to measure transition metal content based on quantitative detection of X-ray fluorescence signals for 3879 purified proteins from several hundred different protein families generated by the New York SGX Research Center for Structural Genomics. Approximately 9% of the proteins analyzed showed the presence of transition metal atoms (Zn, Cu, Ni, Co, Fe, or Mn) in stoichiometric amounts. The method is highly automated and highly reliable based on comparison of the results to crystal structure data derived from the same protein set. To leverage the experimental metalloprotein annotations, we used a sequence-based de novo prediction method, MetalDetector, to identify Cys and His residues that bind to transition metals for the redundancy reduced subset of 2411 sequences sharing <70% sequence identity and having at least one His or Cys. As the HT-XAS identifies metal type and protein binding, while the bioinformatics analysis identifies metal-binding residues, the results were combined to identify putative metal-binding sites in the proteins and their associated families. We explored the combination of this data with homology models to generate detailed structure models of metal-binding sites for representative proteins. Finally, we used extended X-ray absorption fine structure data from two of the purified Zn metalloproteins to validate predicted metalloprotein binding site structures. This combination of experimental and bioinformatics approaches provides comprehensive active site analysis on the genome scale for metalloproteins as a class, revealing new insights into metalloprotein structure and function.

W Shi; M Punta; J Bohon; J Sauder; R DMello; M Sullivan; J Toomey; D Abel; M Lippi; et al.

2011-12-31

326

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

327

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, Jr. , G. E.; Rytuba, J. J.

2000-01-01

328

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

PubMed

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. PMID:11036987

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

2000-10-16

329

X-ray photoelectron spectroscopy investigation of substrate surface pretreatments for diamond nucleation by microwave plasma chemical vapor deposition  

Microsoft Academic Search

The effects of surface pretreatments on the nucleation of diamond on silicon substrates have been studied by quantitative X-ray photoelectron spectroscopy (XPS), SEM and Raman spectroscopy. The methods of surface pretreatments including ultrasonic abrasion, scratching, and DC biasing were used for diamond nucleation enhancement. Diamond films grown by different surface pretreatments and selected intervals in bias-enhanced nucleation were analyzed for

Ming-Jeng Chiang; Min-Hsiung Hon

2000-01-01

330

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

331

In-situ X-ray Absorption Spectroscopy of Supported Ru Catalysts in the Aqueous Phase  

SciTech Connect

The size of supported Ru metal particles on various supports was monitored by in situ X-ray absorption spectroscopy under aqueous phase conditions typical of biomass conversion reactions. In particular, Ru/{gamma}-Al{sub 2}O{sub 3}, Ru/C, Ru/TiO{sub 2}, and Ru/SiO{sub 2} were evaluated at the Ru K edge at 473 K in neutral water and 0.4 M NaOH. The as-prepared samples exposed to air contained oxidized Ru that was subsequently reduced by H{sub 2}-saturated water solution. Significant growth of the metal particles was observed on the Ru/{gamma}-Al{sub 2}O{sub 3} and Ru/SiO{sub 2} samples during the aqueous treatments, whereas the Ru/TiO{sub 2} and Ru/C samples were quite stable under the conditions used here. Results from post-treatment X-ray diffraction and surface area analysis revealed major structural changes of the alumina and silica supports. The structural stability of the carbon and titania account for the lack of metal particle growth on those supports. Because a reference Pt/C catalyst revealed metal particle growth under the same conditions, the results for the Ru/C cannot be generalized to other carbon-supported catalysts and underscores the importance of in situ characterization for heterogeneous catalysts in the aqueous phase.

Ketchie,W.; Maris, E.; Davis, R.

2007-01-01

332

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

333

An x-ray absorption spectroscopy study of Ni-Mn-Ga shape memory alloys.  

PubMed

The austenite to martensite phase transition in Ni-Mn-Ga ferromagnetic shape memory alloys was studied by extended x-ray absorption fine structure (EXAFS) and x-ray absorption near-edge structure (XANES) spectroscopy. The spectra at all the three elements', namely, Mn, Ga and Ni, K-edges in several Ni-Mn-Ga samples (with both Ni and Mn excess) were analyzed at room temperature and low temperatures. The EXAFS analysis suggested a displacement of Mn and Ga atoms in opposite direction with respect to the Ni atoms when the compound transforms from the austenite phase to the martensite phase. The first coordination distances around the Mn and Ga atoms remained undisturbed on transition, while the second and subsequent shells showed dramatic changes indicating the presence of a modulated structure. The Mn rich compounds showed the presence of antisite disorder of Mn and Ga. The XANES results showed remarkable changes in the unoccupied partial density of states corresponding to Mn and Ni, while the electronic structure of Ga remained unperturbed across the martensite transition. The post-edge features in the Mn K-edge XANES spectra changed from a double peak like structure to a flat peak like structure upon phase transition. The study establishes strong correlation between the crystal structure and the unoccupied electronic structure in these shape memory alloys. PMID:23238326

Sathe, V G; Dubey, Aditi; Banik, Soma; Barman, S R; Olivi, L

2013-01-30

334

Strontium localization in bone tissue studied by X-ray absorption spectroscopy.  

PubMed

Strontium has recently been introduced as a pharmacological agent for the treatment and prevention of osteoporosis. We determined the localization of strontium incorporated into bone matrix from dogs treated with Sr malonate by X-ray absorption spectroscopy. A new approach for analyzing the X-ray absorption spectra resulted in a compositional model and allowed the relative distribution of strontium in the different bone components to be estimated. Approximately 35-45% of the strontium present is incorporated into calcium hydroxyapatite (CaHA) by substitution of some of the calcium ions occupying highly ordered sites, and at least 30% is located at less ordered sites where only the first solvation shell is resolved, suggesting that strontium is surrounded by only oxygen atoms similar to Sr(2+) in solution. Strontium was furthermore shown to be absorbed in collagen in which it obtains a higher structural order than when present in serum but less order than when it is incorporated into CaHA. The total amount of strontium in the samples was determined by inductively coupled plasma mass spectrometry, and the amount of Sr was found to increase with increasing dose levels and treatment periods, whereas the relative distribution of strontium among the different components appears to be independent of treatment period and dose level. PMID:24101232

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

2014-02-01

335

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

336

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

337

Lattice instability in high temperature superconducting cuprates probed by x-ray absorption spectroscopy  

NASA Astrophysics Data System (ADS)

In contrast to conventionl superconductivity where phonons lead to the formation of Cooper pairs, in high-tempratures superconductivity (HTSC), the role of electron-phonon coupling has long been neglected. The in-plane Cu-O bonds in HTSC cuprates show unconventionalbroadening at low temperature as carier are doped. Here we focus on high-quality polarized x-ray absorption spectroscopy (XAS)data for a model HTSC system, (La,Sr)2CuO4 (LSCO). Thin film signal crystal samples were prepared by state-of-the-arts MBE, precisely controlling compositions. High quality data was obtained by use of a segmented x-ray detector. the inplane CuO radial distribution function (RDF)in LSCO (x = 0.15)shows broadening as temprature is lowered, which shows a sharp drop at the critical temprature which is followed by a gradual increase (disorder). Comparing the data with resistivity, we find a remarkeble coinsidence between the sharpening and the onset supercondectivity. Since the sharpening of RDF is interpreated as correleted motion of oxyzen atoms (phase coherence due to supercondectivity), the result demonstrate that the super conducting state directly relates to the unconventionl oxyzen displacements in a bond stretching mode. The result will be discussed in relation to the local models of distortion of the diffrent nature (metallic vs. insulating) that is strongly influnced by strain.

Oyanagi, H.; Zhang, C.; Tsukada, A.; Naito, M.

2008-03-01

338

X-ray photoelectron spectroscopy for characterization of bionanocomposite functional materials for energy-harvesting technologies.  

PubMed

The analysis of hybrid multicomponent bioorganic and bioinorganic composite materials related to energy technologies by using X-ray photoelectron spectroscopy is discussed. The approaches and considerations of overcoming the difficulties of analyzing hybrid multicomponent materials are demonstrated for different types of materials used in bioenzyme fuel cells, that is, enzyme immobilization in a hybrid inorganic-organic matrix, analysis of peptide binding and structure in the mediation of silica nanoparticle formation, analysis of enzyme-polymeric multilayered architectures obtained through layer-by-layer assembly, and study of the mechanism of electropolymerization. Thorough optimization of experimental design through analysis of an adequate set of reference materials, relevant timescales of sample preparation and X-ray exposure, careful peak decomposition and cross-correlation between elemental speciation, results in a detailed understanding of the chemistry of nanocomposite constituents and interactions between them. The methodology presented and examples discussed are of significant importance to the scientific and engineering communities focused on the immobilization of enzymes, proteins, peptides, and other large biological molecules on solid substrates. PMID:23703935

Artyushkova, Kateryna; Atanassov, Plamen

2013-07-22

339

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

340

Detrended fluctuation analysis in x-ray photon correlation spectroscopy for determining coarsening dynamics in alloys  

SciTech Connect

We study the dynamics of precipitate coarsening in phase-separating alloys at late stages of phase separation by x-ray photon correlation spectroscopy (XPCS). For analyzing time series of fluctuating speckle intensities from small-angle scattering of coherent x rays, the method of detrended fluctuation analysis (DFA), which is ideal for determining power-law correlations, is applied. We discuss the application of DFA with respect to XPCS data by means of simulated time series. In particular, the effects of different signal-to-noise ratios are examined. Results from measurements of the two model systems Al-6 at. % Ag at 140 deg. C and Al-9 at. % Zn at 0 deg. C are presented. Since the DFA effectively removes adulterating trends in the data, quantitative agreement with Monte Carlo simulations is obtained. It is verified that two different coarsening mechanisms are predominant in the two systems--coarsening either by diffusion of single atoms or by movement of whole precipitates.

Stadler, Lorenz-M.; Sepiol, Bogdan; Pfau, Bastian; Vogl, Gero [Fakultaet fuer Physik, Institut fuer Materialphysik, Universitaet Wien, Strudlhofgasse 4, A-1090 Wien (Austria); Kantelhardt, Jan W. [Fachbereich Physik und Zentrum fuer Computational Nanoscience, Martin-Luther-Universitaet Halle-Wittenberg, D-06099 Halle (Germany); Weinkamer, Richard [Max Planck Institute of Colloids and Interfaces, Research Campus Golm, D-14424 Potsdam (Germany)

2006-10-15

341

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

342

Gate oxide process control optimization by x-ray photoelectron spectroscopy in a semiconductor fabrication line  

SciTech Connect

X-ray photoelectron spectroscopy is a metrology technique that is used for in-line control of decoupled plasma nitridation processes in the fabrication of logic devices. This article shows XPS results of thickness and composition obtained on two types of gate oxide nitrided by a decoupled plasma nitridation process. Measurements are performed in specific test structures with an x-ray spot which can be focused down to 35 {mu}m, enabling process control directly on products. First, XPS is used to characterize and quantify the chemical composition of a SiON layer. The Results show that the nitrogen composition in a SiON layer decreases at a fast rate during the initial days after nitridation processing and stabilizes with time. Second, measurements are performed on products with the objective of transferring process control from monitor to product wafers. In this regard, comparison of nitrogen dose and thickness uniformity on monitor and pattern wafers show similar trends, indicating that measurements of nitrogen dose and thickness on monitor and product wafers give the same information. Third, different mapping protocols are studied on products to identify the best compromise between throughput and an optimized mapping representative of the process distribution. An optimized process control strategy of gate oxides with results is discussed in this article.

Le Gouil, A.; Cabuil, N.; Dupeyrat, P.; Dickson, B.; Kwan, M.; Barge, D.; Gurer, E.; Doclot, O.; Royer, J.-C. [STMicroelectronics, Metrology, 850 rue J. Monnet, 38926 Crolles Cedex (France); Revera, Incorporated, 810 Kifer Road, Sunnyvale, California 94086 (United States); STMicroelectronics, Metrology, 850 rue J. Monnet, 38926 Crolles Cedex (France); Revera, Incorporated, 810 Kifer Road, Sunnyvale, California 94086 (United States); STMicroelectronics, Metrology, 850 rue J. Monnet, 38926 Crolles Cedex (France); CEA/LETI-Minatec, 17 rue des Martyrs, 38000 Grenoble (France)

2008-07-15

343

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

344

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

345

X-ray photoelectron spectroscopy investigation of the carburization of 310 stainless steel  

NASA Astrophysics Data System (ADS)

The surface of 310 stainless steel (310SS) samples was investigated by X-ray photoelectron spectroscopy (XPS) after 500 h cyclic exposure to two carburizing atmospheres: CH 4 (2%)-H 2 (98%) at 800 °C, and CH 4 (10%)-H 2 (90%) at 1100 °C. The depth distribution of various elements in the surface region was obtained by XPS after successive cycles of argon etching. The microstructure of the alloy was observed by scanning electron microscopy (SEM) and the phases formed during the exposure were analyzed by X-ray diffraction (XRD). The results showed that the major phases that were formed within few micrometer depth during exposure at 800 °C include both iron and chromium carbides. (Mn, Cr) oxide was also formed as a result of the reaction with the residual oxygen of the atmosphere. A region of few microns width that was relatively depleted of chromium was formed under the surface as a result of the outwards diffusion of chromium. The exposure to the reducing atmosphere at 1100 °C led to the formation of various iron and chromium carbides. No oxide was formed during exposure. In all exposed samples, the surface was Cr enriched while nickel remained buried under the surface region that reacted with the atmosphere.

Tabet, N.; Allam, I.; Yin, R. C.

2003-12-01

346

Direct observation of pentacene-thiol interaction using x-ray spectroscopy  

NASA Astrophysics Data System (ADS)

There has been an intense interest in the surface modification of the source-drain electrodes for organic field effect transistors (OFETs) to improve their performance. A number of thiol based self assembled monolayers demonstrated improvements to the contact resistance and channel performance. Morphological improvements at the contacts, a change in the effective work function, and charge transfer between the thiols and the semiconductor have all been credited with the observed performance improvements. Using in-situ semiconductor deposition together with x-ray photoelectron spectroscopy and near-edge x-ray absorption fine structure, we are able to directly probe two technologically relevant OFET stacks. This work directly measures the interaction between pentacene and two thiols which have been associated to contact improvement: an electroneutral thiol (1-hexadecanethiol) and an electronegative thiol (pentafluorobenzenethiol). Based on our results we observe no chemical interaction between pentacene and the thiol. The electrical improvements to transistor performance, based on these systems, can be attributed to work function shifts of the contacts and morphological improvements of the organic semiconductor.

Jia, Zhang; Lee, Vincent; Floreano, Luca; Verdini, Alberto; Cossaro, Albano; Morgante, Alberto; Kymissis, Ioannis

2010-03-01

347

Soft x-ray spectroscopy and microspectroscopy of magnetic and naturally occurring materials  

NASA Astrophysics Data System (ADS)

The ability to obtain spectral information about the electronic, chemical, and magnetic structure of a material on a micron sized spatial scale has been a premiere advantage to using an X-ray photoemission electron microscope (X-PEEM) at a synchrotron radiation facility. The micro-spectroscopic ability of the X-PEEM currently and the ease at which it can be transformed into a fall spectromicroscopy technique make it an ideal candidate for the future. To this end, presented is material from the two techniques, spectroscopy and microscopy, and a micro-spectroscopy study of the surface of a naturally occurring mineral Ilmenite. Results from the ligand field multiplet model calculations are presented along with a configuration interaction approach and compared with the experimentally measured spectra from a number of naturally occurring transition metal compounds of Mn and Fe. The interpretation with a ligand field multiplet model accounts well for the observed spectra and due to its simplicity this model yields accurate and well defined electronic structure parameters. Utilizing the X-ray magnetic circular dichroism (XMCD) the sum rules, we show that the spin to orbital moment for ultra-thin Fe films on Pd(001) and Ag(001) increase as the film thickness decreases but for Fe films grown on ferromagnetic substrates such as fcc Co and Ni the spin to orbital moment remains constant. We also show a dependence of the film coercivity on the amount of mismatch between the Fe overlayers and the substrate. It is theorized that this dramatic increase in the coercive field is due to mismatch dislocations which occur when the film is relaxing into its natural state. A link between anomalous uniaxial anisotropy displayed in ultra-thin films of fcc Co/Cu(001) and the magnetic domain structure is shown. A two-site simple model is used to explain the anomalous uniaxial anisotropy and a correlation between domain structure and underlying crystal topography is theorized. Finally, a case study of lamellar domains present in natural ilmenite is shown which combines the spatial resolution with spectroscopic data. High-resolution spectroscopy from these two different regions reveals fine structure from iron atoms in two different charge states, and titanium in a single phase. These results show that qualitative as well as quantitative surface chemistry studies can be performed on natural mineral samples using X-ray photoemission electron microscopy. (Abstract shortened by UMI.)

Droubay, Timothy Charles

348

Micro-X-Ray Fluorescence and the Old Masters . Non-destructive in situ characterisation of the varnish of historical Low Countries stringed musical instruments  

NASA Astrophysics Data System (ADS)

In recent years, a growing attention has been addressed to the study of the varnish from early musical instruments. The surfaces of nine historical Low Countries stringed musical instruments from the collection of the "Musical Instruments Museum" in Brussels were non-destructively analysed by in situ micro-X-Ray Fluorescence spectroscopy in dispersive mode. It was found that the main pigments dispersed in the varnish were iron- and manganese-based earths. The presence of a chromium-based pigment in one of the analysed instruments makes it appreciably different from the others. Other findings were discussed and compared with previously published results. The collection of such information plays a relevant role in the recovery of the applied formulations that is an interesting issue for conservators, luthiers and art historians.

Caruso, Francesco; Saverwyns, Steven; Van Bos, Marina; Chillura Martino, Delia Francesca; Ceulemans, Anne-Emmanuelle; de Valck, Joris; Caponetti, Eugenio

2012-04-01

349

Local structure analysis of boron-doped graphite by soft x-ray emission and absorption spectroscopy using synchrotron radiation  

NASA Astrophysics Data System (ADS)

The local structure of boron-doped highly oriented graphite films was determined via soft x-ray emission and absorption spectroscopy using synchrotron radiation. Analysis of the BK and CK x-ray emission spectra using the discrete variational-X? molecular orbital method clarified that boron atoms are chemisorbed onto graphite by substituting for carbon atoms in the carbon hexagonal rings. Compared to graphite, boron-doped graphite exhibits spectral differences in the higher edge of the CK x-ray emission spectrum and the CK x-ray absorption edge. Such a spectral profile of boron-doped graphite, which reflects the band structure, is well explained by the chemisorbed boron structure.

Hanafusa, Atsushi; Muramatsu, Yasuji; Kaburagi, Yutaka; Yoshida, Akira; Hishiyama, Yoshihiro; Yang, Wanli; Denlinger, Jonathan D.; Gullikson, Eric M.

2011-09-01

350

Soft x-ray imaging system for picosecond time-resolved absorption spectroscopy using a femtosecond-laser-plasma source  

SciTech Connect

We have developed an imaging system for time-resolved soft x-ray absorption spectroscopy. The system consists of a femtosecond-laser-plasma x-ray source for time-resolved measurements and an x-ray microscope with critical illumination for imaging. The temporal and spatial resolutions were 23 ps and better than 12.5 {mu}m, respectively. We applied this system to the measurement of an aluminum ablation plume induced by irradiation with a 120 fs laser pulse. The shift of the L-shell photoabsorption edge in the expanding plume was observed in the spatiotemporally resolved absorbance spectrum. The space- and time-resolved x-ray absorption spectrum of an expanding laser ablation plume was clearly obtained using the developed system.

Okano, Yasuaki; Oguri, Katsuya; Nishikawa, Tadashi; Nakano, Hidetoshi [NTT Basic Research Laboratories, NTT Corporation, 3-1 Morinosato Wakamiya, Atsugi, Kanagawa 243-0198 (Japan)

2006-04-15

351

Atmospheric Electron-induced X-Ray Spectrometer (AEXS) Instrument Development  

NASA Technical Reports Server (NTRS)

Instrument Development: The membrane properties were investigated in detail due to its critical role. A series of experiments determined that our designed membranes have high electron transmission, yet are capable of isolating high vacuum, are able to withstand differential pressure in excess of one atmosphere, survive vibrational shocks of a magnitude to be expected during a planetary mission. Our initial work has been with a 10 keV source and a 200 nm thick Silicon Nitride (SiN) encapsulation membrane micro-fabricated within a Si support frame (1.5 mm x 1.5 mm window openings. Fig 2 compares the spectra taken with the 10 keV source with spectra taken within SEM. Introduction: This paper describes the progress in the development of the AEXS instrument in our laboratory at JPL. The AEXS is a novel miniature instrument[1-3] based on the excitation of characteristic X-Ray Fluorescence (XRF) and luminescence spectra using a focused electron beam, for non-destructive evaluation of surfaces of samples in planetary ambient atmosphere. In situ operation is obtained through the use of a thin electron transmissive membrane to isolate the vacuum within the AEXS electron source from the outside ambient atmosphere. The impinging electrons excite XRF spectra from the irradiated spots on samples in external atmosphere with high-to-medium (sub-mm to cm-scale) spatial resolution at Mars atmospheric pressure. The XRF spectra are analyzed using an energy-dispersive detector to determine surface elemental composition, or in the case of electron-induced luminescence to identify unusual formations on surface that cathodo-luminescence (CL). The AEXS system (Fig 1) consists of a high-energy (>10keV) electron gun encapsulated by the isolation membrane, an EDX detection and analyzer system to determine the elemental abundance, an optional CL detection system, and a high voltage power supply. The approach to demonstrating a proof of concept of the AEXS has been through 1) demonstrating the viability of micro-fabricated membranes, 2) assembling AEXS setups with increasingly integrated functional components, and 3) simulating the AEXS observational capabilities. This paper will focus on description of the development of the instrument.

Wilcox, J. Z.; Urgiles, E.; Toda, R.; George, T.; Crisp, J.

2005-01-01

352

High-rate x-ray spectroscopy in mammography with a CdTe detector: A digital pulse processing approach  

SciTech Connect

Purpose:Direct measurement of mammographic x-ray spectra under clinical conditions is a difficult task due to the high fluence rate of the x-ray beams as well as the limits in the development of high resolution detection systems in a high counting rate environment. In this work we present a detection system, based on a CdTe detector and an innovative digital pulse processing (DPP) system, for high-rate x-ray spectroscopy in mammography. Methods: The DPP system performs a digital pile-up inspection and a digital pulse height analysis of the detector signals, digitized through a 14-bit, 100 MHz digitizer, for x-ray spectroscopy even at high photon counting rates. We investigated on the response of the digital detection system both at low (150 cps) and at high photon counting rates (up to 500 kcps) by using monoenergetic x-ray sources and a nonclinical molybdenum anode x-ray tube. Clinical molybdenum x-ray spectrum measurements were also performed by using a pinhole collimator and a custom alignment device. Results: The detection system shows excellent performance up to 512 kcps with an energy resolution of 4.08% FWHM at 22.1 keV. Despite the high photon counting rate (up to 453 kcps), the molybdenum x-ray spectra, measured under clinical conditions, are characterized by a low number of pile-up events. The agreement between the attenuation curves and the half value layer values, obtained from the measured spectra, simulated spectra, and from the exposure values directly measured with an ionization chamber, also shows the accuracy of the measurements. Conclusions: These results make the proposed detection system a very attractive tool for both laboratory research and advanced quality controls in mammography.

Abbene, L.; Gerardi, G.; Principato, F.; Del Sordo, S.; Ienzi, R.; Raso, G. [Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy) and INAF/IASF Palermo, Via Ugo La Malfa 153, 90146 Palermo (Italy); Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy); INAF/IASF Palermo, Via Ugo La Malfa 153, 90146 Palermo (Italy); Istituto di Radiologia, Policlinico, 90100 Palermo (Italy); Dipartimento di Fisica e Tecnologie Relative, Universita di Palermo, Viale delle Scienze, Edificio 18, Palermo 90128 (Italy)

2010-12-15

353

Room temperature oxidation kinetics of Si nanoparticles in air, determined by x-ray photoelectron spectroscopy  

SciTech Connect

The air oxidation kinetics of low coverages of {approx}5 nm Si nanoparticles, deposited by pulsed excimer laser ablation (KrF, 248 nm) in He, have been characterized by x-ray photoelectron spectroscopy. A simple model, based on the evolution of the Si 2p spectral components during oxidation, has been developed to determine the nanoparticle oxide thickness. It is found that the short-term oxide thickness is greater, and the long-term room-temperature air oxidization rate of these nanoparticles is less, than those reported for bulk a-Si and c-Si. The results are also consistent with an earlier transmission electron microscope observation of the oxidation of larger Si particles at higher temperatures. The greater short-term oxide thickness may be attributed to surface defects on the prepared Si nanoparticles, and lower long-term oxidation rate is due to the nonlinear decrease of oxygen diffusion in spherical systems.

Yang, D.-Q.; Gillet, Jean-Numa; Meunier, M.; Sacher, E. [Regroupement Quebecois des Materiaux de Pointe and Departement de Genie Physique, Ecole Polytechnique Case Postale 6079, succursale Centre-Ville, Montreal, Quebec H3C 3A7 (Canada)

2005-01-15

354

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

355

X-ray photoelectron spectroscopy study of chemically-etched Nd-Ce-Cu-O surfaces  

NASA Technical Reports Server (NTRS)

Acetic acid, Br2, and HCl solutions are investigated for removing insulating species from Nd(1.85)Ce(0.15)CuO(4-delta) (NCCO) thin film surfaces. X-ray photoelectron spectroscopy (XPS) shows that the HCl etch is most effective, yielding O 1s spectra comparable to those obtained from samples cleaned in vacuum and a clear Fermi edge in the valence band region. Reduction and oxidation reversibly induces and eliminates, respectively, Fermi level states for undoped samples, but has no clearly observable effect on the XPS spectra for doped samples. Reactivity to air is much less for NCCO compared to hole superconductors, which is attributed to the lack of reactive alkaline earth elements in NCCO.

Vasquez, R. P.; Gupta, A.; Kussmaul, A.

1991-01-01

356

An x ray photoelectron spectroscopy study of Au(x)In(y) alloys  

NASA Technical Reports Server (NTRS)

Four gold-indium alloys were studied by x ray photoelectron spectroscopy. The binding energies and intensity ratios of the Au 4f7/2 and In 3d5/2 core levels were determined for the bulk alloy compositions of Au(10 percent In), Au3In, AuIn, and AuIn2. These values were determined for the native oxides on the materials, for the surfaces prepared by ion bombardment to remove the oxide and for surfaces scraped in-situ with a ceramic tool to expose the bulk composition. These results furnish calibration values that allow determination of the composition of thin films of this alloy system. In addition the binding energies add to the data base for understanding the effect of alloying on core level binding energies. As an illustration, these results are used to determine the composition of a series of alloy films formed by incongruent evaporation of an alloy charge.

Jayne, Douglas T.; Fatemi, Navid S.; Weizer, Victor G.

1990-01-01

357

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

358

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

PubMed

A vapor-deposited NH(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(2), whose concentration as a function of the absorbed energy has been quantified to 0.13 molecule/eV. The stability of N(2) in solid NH(3) has been also studied, showing that N(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(2), N(2)H(2), and N(3)(-). PMID:20568865

Parent, Ph; Bournel, F; Lasne, J; Lacombe, S; Strazzulla, G; Gardonio, S; Lizzit, S; Kappler, J-P; Joly, L; Laffon, C; Carniato, S

2009-10-21

359

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

360

Deep X-ray spectroscopy of obscured AGN in the XMM-CDFS  

NASA Astrophysics Data System (ADS)

Heavy obscuration represents an important phase of AGN evolution and is expected to play a key role in the feedback mechanisms self regulating the SMBH growth. The signature of absorption is the presence of an exponential cut-off at low energy and/or a reflected X-ray spectrum plus a strong Iron line. The results of a systematic analysis of the brightest ~200 sources in the deep XMM survey of the CDFS will be be presented, namely: the distribution of power law spectral indices and iron line equivalent widths, the absorption distribution and the evolution of obscured fraction and, in particular the properties of Compton thick AGN up to redshifts of about 4. The power of deep spectroscopy to obtain more reliable redshifts estimates than currently available for optically faint sources will be highlighted, along with a few examples of synergies between ultra-deep Chandra (7 Ms) and XMM observations.

Comastri, A.; Ranalli, P.; Vignali, C.; Georgantopoulos, I.; Carrera, F.; Iwasawa, K.; Gilli, R.; Cappelluti, N.; Brusa, M.; Civano, F.

2014-07-01

361

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

NASA Technical Reports Server (NTRS)

Radiofrequency sputtering was used to deposit Mo2C, Mo2B5, and MoSi2 coatings on 440C steel substrates. Both sputter etched and preoxidized substrates were used, and the films were deposited with and without a substrate bias of -300 V. The composition of the coatings was measured as a function of depth by X-ray photoelectron spectroscopy combined with argon ion etching. In the interfacial region there was evidence that bias produced a graded interface in Mo2B5 but not in Mo2C. Oxides of iron and of all film constituents except carbon were presented in all cases but the iron oxide concentration was higher and the layer thicker on the preoxidized substrates. The film and iron oxides were mixed in the MoSi2 and Mo2C films but layered in the Mo2B5 film. The presence of mixed oxides correlates with enhanced film adhesion.

Wheeler, D. R.; Brainard, W. A.

1978-01-01

362

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

SciTech Connect

Results are given of the investigation of the coordination of aluminum atoms in seven types of porous anodic aluminum oxides by ultrasoft x-ray emission spectroscopy. It is shown that a difference exists between the anodic aluminum oxides obtained in different electrolytes. The change in the relative intensity of the maxima of the Al L/sub 2,3/ emission band was used to assess the coordination number of aluminum for seven different porous anodic aluminum oxides. It has been found that the coordination numbers for all investigated oxides, except for the one obtained in sodium carbonate solution, lie in the interval from 4 to 6. An increase in the coordination of aluminum atoms with respect to oxygen has been detected in the surface layers of anodic coatings.

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

1988-12-01

363

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

364

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

365

X-ray Polarization Spectroscopy to Study Hot Electron Transport in High Intensity Laser Produced Plasma  

NASA Astrophysics Data System (ADS)

X-ray polarization spectroscopy was used to study anisotropy of hot electron velocity distribution functions (VDFs) in a plasma generated at 10^18W/cm^2. Chlorinated triple-layer targets were irradiated and polarization degree of Cl Hea line was measured as a function of overcoat thickness. The polarization degree, nearly zero at the surface, becomes negative then positive, and finally becomes zero with increase in the thickness. This result indicate that VDF in under-dens region is affected with laser field, and that in over-dense region is with acceleration along the laser propagation. Depolarization seen in the surface and dense region is consistent with predictions with a time-dependent atomic kinetics code [1]. [1] T. Kawamura, et al., PRL 99, 115003 (2007)

Nishimura, H.; Inubushi, Y.; Okano, Y.; Fujioka, S.; Kai, T.; Kawamura, T.; Batani, D.; Morace, A.; Redaelli, R.; Fourment, C.; Santos, J.; Malka, G.; Boscheron, A.; Casner, A.; Koenig, M.; Jhozaki, T.; Nagatomo, H.; Mima, K.

2008-11-01

366

Precision spectroscopy of light kaonic atom X-rays in the SIDDHARTA experiment  

SciTech Connect

The KN system at rest makes a sensitive testing ground for low energy QCD. At the DA{Phi}NE electron-positron collider of Laboratori Nazionali di Frascati we study kaonic atoms, taking advantage of the low-energy kaons from {Phi}-mesons decaying nearly at rest. The DEAR (DA{Phi}NE Exotic Atom Research) experiment at LNF delivered the most precise data on kaonic hydrogen up to now. DEAR and its follow-up experiment SIDDHARTA (Silicon Drift Detector for Hadronic Atom Research by Timing Application) are using X-ray spectroscopy of kaonic atoms to measure the strong interaction induced shift and width of the ground state. SIDDHARTA is the first experiment on kaonic helium-3 and deuterium ever, and kaonic hydrogen was remeasured with improved precision.

Cargnelli, M.; Ishiwatari, T.; Marton, J.; Widmann, E.; Zmeskal, J. [Stefan Meyer Institut of the Austrian Academy of Sciences, Vienna, 1090, Boltzmanngasse 3 (Austria); Bazzi, M.; Bragadireanu, A. M.; Curceanu, C.; Guaraldo, C.; Iliescu, M.; Sandri, P. Levi; Lucherini, V.; Okada, S.; Pietreanu, D.; Vidal, A. Romero; Scordo, A.; Sirghi, D. L.; Sirghi, F; Doce, O. Vazquez [INFN, Laboratori Nazionali di Frascati, C.P. 13, Via E. Fermi 40,I-00044 Frascati, Roma (Italy); Beer, G. [Dep. of Physics and Astronomy, University of Victoria, P.O.Box 3055, Victoria B.C. V8W3P6 (Canada)

2011-10-24

367

A novel X-ray photoelectron spectroscopy study of the Al/SiO2 interface  

NASA Technical Reports Server (NTRS)

The nondestructive measurement of the chemical and physical characteristics of the interface between bulk SiO2 and thick aluminum films is reported. Both X-ray phototelectron spectroscopy (XPS) and electrical measurements of unannealed, resistively evaporated Al films on thermal SiO2 indicate an atomically abrupt interface. Post metallization annealing at 450 C induces reduction of the SiO2 by the aluminum, at a rate consistent with the bulk reaction rate. The XPS measurement is performed from the SiO2 side after the removal of the Si substrate with XeF2 gas and thinning of the SiO2 layer with HF:ETOH. This represents a powerful new approach to the study of metal-insulator and related interfaces.

Hecht, M. H.; Vasquez, R. P.; Grunthaner, F. J.; Zamani, N.; Maserjian, J.

1985-01-01

368

Localized high spin states in transition-metal dimers: X-ray absorption spectroscopy study  

SciTech Connect

X-ray absorption spectroscopy provides direct evidence for localized valence electrons in Cr{sub 2}{sup +}, Mn{sub 2}{sup +}, and CrMn{sup +} dimer cations. Bonding in these transition-metal molecules is predominantly mediated by 4s electrons. This behavior is markedly different from other 3d transition-metal dimers with open 3d subshells and can be ascribed to the highly stable 3d{sup 5}({sup 6}S) configuration of the 3d subshell in chromium and manganese atoms and ions. In Cr{sub 2}{sup +}, Mn{sub 2}{sup +}, and CrMn{sup +}, 3d electron localization indicates local high spin states.

Lau, J. T.; Hirsch, K.; Langenberg, A.; Probst, J.; Richter, R.; Rittmann, J.; Vogel, M.; Zamudio-Bayer, V.; Moeller, T.; Issendorff, B. von [Institut fuer Optik und Atomare Physik, Technische Universitaet Berlin, EW 3-1, Hardenbergstrasse 36, D-10623 Berlin (Germany); Fakultaet fuer Physik, FMF, Universitaet Freiburg, Stefan-Meier-Strasse 21, D-79104 Freiburg (Germany)

2009-06-15

369

In Situ X-Ray Photoelectron Spectroscopy of Model Catalysts: At the Edge of the Gap  

NASA Astrophysics Data System (ADS)

We present high-pressure x-ray photoelectron spectroscopy (HP-XPS) and first-principles kinetic Monte Carlo study addressing the nature of the active surface in CO oxidation over Pd(100). Simultaneously measuring the chemical composition at the surface and in the near-surface gas phase, we reveal both O-covered pristine Pd(100) and a surface oxide as stable, highly active phases in the near-ambient regime accessible to HP-XPS. Surprisingly, no adsorbed CO can be detected during high CO2 production rates, which can be explained by a combination of a remarkably short residence time of the CO molecule on the surface and mass-transfer limitations in the present setup.

Blomberg, S.; Hoffmann, M. J.; Gustafson, J.; Martin, N. M.; Fernandes, V. R.; Borg, A.; Liu, Z.; Chang, R.; Matera, S.; Reuter, K.; Lundgren, E.

2013-03-01

370

X-ray absorption spectroscopy of doped Bi2Se3 and Bi2Te3  

NASA Astrophysics Data System (ADS)

Topological insulators are a prototypical system to investigate correlated electron physics. Analogous to quantum hall states, these remarkable materials have conducting surface/edge states surrounding an insulating in the bulk state. Unlike quantum hall systems the conducting states of topological insulators do no arise from an applied magnetic field but instead emerge as a result of spin-orbit interactions. Furthermore, doping with different 3d-metals can significantly alter the electronic structure, inducing superconductivity in the case of CuxBi2-xSe3, and ferromagnetism in Bi2-xMnxTe3. In an effort to elucidate the role of the local bonding environment on the electronic structure in the chalchogenide topological insulators, Bi2Te3 and Bi2Se3 with various transition metal as dopants, we have preformed a series of soft x-ray absorption spectroscopy measurements.

McChesney, Jessica; Rosenberg, Richard; Chung, Duck Young; Kanatzidis, Mercouri

2013-03-01

371

Reconstruction of Confocal Micro-X-ray Fluorescence Spectroscopy Depth Scans Obtained with a Laboratory Setup.  

PubMed

Depth profiling with confocal micro-X-ray fluorescence spectroscopy (confocal micro-XRF) is a nondestructive analytical method for obtaining elemental depth profiles in the micrometer region. Up until now, the quantitative reconstruction of thicknesses and elemental concentration of stratified samples has been only possible with monochromatic, thus, synchrotron radiation. In this work, we present a new calibration and reconstruction procedure, which renders quantification in the laboratory feasible. The proposed model uses the approximation of an effective spot size of the optic in the excitation channel and relies on the calibration of the transmission of this lens beforehand. Calibration issues are discussed and validation measurements on thick multielement reference material and a stratified system are presented. PMID:25162502

Mantouvalou, Ioanna; Wolff, Timo; Seim, Christian; Stoytschew, Valentin; Malzer, Wolfgang; Kanngießer, Birgit

2014-10-01

372

X-ray photoelectron spectroscopy study of catalyzed aluminum carbide formation at aluminum-carbon interfaces  

NASA Technical Reports Server (NTRS)

Aluminum carbide may form at aluminum-graphite interfaces during the high-temperature processing of graphite fiber-reinforced aluminum metal matrix composites. The chemical interactions leading to the formation of the aluminum carbide in the solid state involve the breaking of the carbon-carbon bonds within the graphite, the transport of the carbon atoms across the interface, and the reaction with the aluminum to form Al4C3. The aluminum carbide formation process has been followed using X-ray photoelectron spectroscopy of model, thin-film, reaction couples. The overall reaction is shown to be catalyzed by the presence of water vapor. Water at the interface increases reaction kinetics by apparently weakening the bonds between the surface carbon atoms and their substrate. This result is in general agreement with what is known to occur during the oxidation of graphite in air.

Rabenberg, L.; Maruyama, Benji

1990-01-01

373

Stereoscopic electron spectroscopy of solar hard X-ray flares with a single spacecraft  

E-print Network

Hard X-ray (HXR) spectroscopy is the most direct method of diagnosing energetic electrons in solar flares. Here we present a technique which allows us to use a single HXR spectrum to determine an effectively stereoscopic electron energy distribution. Considering the Sun's surface to act as a 'Compton mirror' allows us to look at emitting electrons also from behind the source, providing vital information on downward-propagating particles. Using this technique we determine simultaneously the electron spectra of downward and upward directed electrons for two solar flares observed by the Ramaty High Energy Solar Spectroscopic Imager (RHESSI). The results reveal surprisingly near-isotropic electron distributions, which contrast strongly with the expectations from the standard model which invokes strong downward beaming, including collisional thick-target model.

Eduard P. Kontar; John C. Brown

2006-11-06

374

X-Ray absorption spectroscopy investigation of 1-alkyl-3-methylimidazolium bromide salts  

NASA Astrophysics Data System (ADS)

X-ray absorption spectroscopy (XAS) has been used to unveil the bromide ion local coordination structure in 1-alkyl-3-methylimidazolium bromide [Cnmim]Br ionic liquids (ILs) with different alkyl chains. The XAS spectrum of 1-ethyl-3-methylimidazolium bromide has been found to be different from those of the other members of the series, from the butyl to the decyl derivatives, that have all identical XAS spectra. This result indicates that starting from 1-buthyl-3-methylimidazolium bromide the local molecular arrangement around the bromide anion is the same independently from the length of the alkyl chain, and that the imidazolium head groups in the liquid ILs with long alkyl chains assume locally the same orientation as in the [C4mim]Br crystal. With this study we show that the XAS technique is an effective direct tool for unveiling the local structural arrangements around selected atoms in ILs.

D'Angelo, Paola; Zitolo, Andrea; Migliorati, Valentina; Bodo, Enrico; Aquilanti, Giuliana; Hazemann, Jean Louis; Testemale, Denis; Mancini, Giordano; Caminiti, Ruggero

2011-08-01

375

X-Ray absorption spectroscopy investigation of 1-alkyl-3-methylimidazolium bromide salts.  

PubMed

X-ray absorption spectroscopy (XAS) has been used to unveil the bromide ion local coordination structure in 1-alkyl-3-methylimidazolium bromide [C(n)mim]Br ionic liquids (ILs) with different alkyl chains. The XAS spectrum of 1-ethyl-3-methylimidazolium bromide has been found to be different from those of the other members of the series, from the butyl to the decyl derivatives, that have all identical XAS spectra. This result indicates that starting from 1-buthyl-3-methylimidazolium bromide the local molecular arrangement around the bromide anion is the same independently from the length of the alkyl chain, and that the imidazolium head groups in the liquid ILs with long alkyl chains assume locally the same orientation as in the [C(4)mim]Br crystal. With this study we show that the XAS technique is an effective direct tool for unveiling the local structural arrangements around selected atoms in ILs. PMID:21861574

D'Angelo, Paola; Zitolo, Andrea; Migliorati, Valentina; Bodo, Enrico; Aquilanti, Giuliana; Hazemann, Jean Louis; Testemale, Denis; Mancini, Giordano; Caminiti, Ruggero

2011-08-21

376

Resolution enhancement in coherent x-ray diffraction imaging by overcoming instrumental noise.  

PubMed

We report that reference objects, strong scatterers neighboring weak phase objects, enhance the phase retrieval and spatial resolution in coherent x-ray diffraction imaging (CDI). A CDI experiment with Au nano-particles exhibited that the reference objects amplified the signal-to-noise ratio in the diffraction intensity at large diffraction angles, which significantly enhanced the image resolution. The interference between the diffracted x-ray from reference objects and a specimen also improved the retrieval of the phase of the diffraction signal. The enhancement was applied to image NiO nano-particles and a mitochondrion and confirmed in a simulation with a bacteria phantom. We expect that the proposed method will be of great help in imaging weakly scattering soft matters using coherent x-ray sources including x-ray free electron lasers. PMID:25402155

Kim, Chan; Kim, Yoonhee; Song, Changyong; Kim, Sang Soo; Kim, Sunam; Kang, Hyon Chol; Hwu, Yeukuang; Tsuei, Ku-Ding; Liang, Keng San; Noh, Do Young

2014-11-17

377

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

378

Testing of High-Resolution SI and GE Analyzers for X-Ray Raman Scattering and X-Ray Emission Spectroscopy  

SciTech Connect

A project at Stanford Linear Accelerator Center (SLAC) is currently underway for the building of a new multi-crystal x-ray spectrometer that will be used to probe the fundamental structures of light elements, including water, as well as 3d transition metals, such as metalloproteins, in dilute systems. Experimentation for determining the focal lengths for the prospective high-resolution, spherically-curved silicon (Si) and germanium (Ge) analyzers for the instrument and the energy resolutions at their respective focal points is described. The focal lengths of the Si and Ge analyzers being sampled were found by minimizing the focal size made from a diffused helium-neon (HeNe) gas laser operating at 632 nm (0.95 meV). Afterwards, the energy resolutions were determined by using synchrotron radiation (SR), in the range from 6-16 keV energies. The experiments were performed at Beamline 10-2 at the Stanford Synchrotron Radiation Laboratory (SSRL), a division of SLAC. This data, along with the energies of the incident beams, was used to determine which samples are most effective at focusing x-rays to the highest spatial and energy resolution. Sample Si (440)A, with a focal length of 1015.2 mm, had the best energy resolution. Furthermore, a new multi-crystal goniometer was tested and commissioned. As part of this work, the device was prealigned into Rowland geometry, in order to facilitate the process of finding a single high-energy resolution x-ray focus for all 7 analyzers.

Reynolds, K.W.; Bergmann, U.

2005-01-01

379

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

380

L-Edge X-ray Absorption Spectroscopy of Dilute Systems Relevant to Metalloproteins Using an X-ray Free-Electron Laser  

PubMed Central

L-edge spectroscopy of 3d transition metals provides important electronic structure information and has been used in many fields. However, the use of this method for studying dilute aqueous systems, such as metalloenzymes, has not been prevalent because of severe radiation damage and the lack of suitable detection systems. Here we present spectra from a dilute Mn aqueous solution using a high-transmission zone-plate spectrometer at the Linac Coherent Light Source (LCLS). The spectrometer has been optimized for discriminating the Mn L-edge signal from the overwhelming O K-edge background that arises from water and protein itself, and the ultrashort LCLS X-ray pulses can outrun X-ray induced damage. We show that the deviations of the partial-fluorescence yield-detected spectra from the true absorption can be well modeled using the state-dependence of the fluorescence yield, and discuss implications for the application of our concept to biological samples. PMID:24466387

Mitzner, Rolf; Rehanek, Jens; Kern, Jan; Gul, Sheraz; Hattne, Johan; Taguchi, Taketo; Alonso-Mori, Roberto; Tran, Rosalie; Weniger, Christian; Schröder, Henning; Quevedo, Wilson; Laksmono, Hartawan; Sierra, Raymond G.; Han, Guangye; Lassalle-Kaiser, Benedikt; Koroidov, Sergey; Kubicek, Katharina; Schreck, Simon; Kunnus, Kristjan; Brzhezinskaya, Maria; Firsov, Alexander; Minitti, Michael P.; Turner, Joshua J.; Moeller, Stefan; Sauter, Nicholas K.; Bogan, Michael J.; Nordlund, Dennis; Schlotter, William F.; Messinger, Johannes; Borovik, Andrew; Techert, Simone; de Groot, Frank M. F.; Föhlisch, Alexander; Erko, Alexei; Bergmann, Uwe; Yachandra, Vittal K.; Wernet, Philippe; Yano, Junko

2013-01-01

381

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

E-print Network

We describe the concepts and technical realization 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). 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 deg 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 (PGM) operating in collimated light. The ultimate resolving power E/dE is above 33000 at 1 keV photon energy. The choice of blazed vs lamellar gratings and optimization of their profile parameters is described. Due to glancing angles on the mirrors as well as optimized groove densities and profiles of the gratings, high photon flux is achieved up to 1.0e13 photons/s/0.01%BW at 1 keV. Ellipsoida...

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

2009-01-01

382

Unveiling the nature of INTEGRAL objects through optical spectroscopy. IX. Twenty two more identifications, and a glance into the far hard X-ray Universe  

NASA Astrophysics Data System (ADS)

Since its launch in October 2002, the INTEGRAL satellite has revolutionized our knowledge of the hard X-ray sky thanks to its unprecedented imaging capabilities and source detection positional accuracy above 20 keV. Nevertheless, many of the newly-detected sources in the INTEGRAL sky surveys are of unknown nature. The combined use of available information at longer wavelengths (mainly soft X-rays and radio) and of optical spectroscopy on the putative counterparts of these new hard X-ray objects allows us to pinpoint their exact nature. Continuing our long-standing program that has been running since 2004, and using 6 different telescopes of various sizes together with data from an online spectroscopic survey, here we report the classification through optical spectroscopy of 22 more unidentified or poorly studied high-energy sources detected with the IBIS instrument onboard INTEGRAL. We found that 16 of them are active galactic nuclei (AGNs), while the remaining 6 objects are within our Galaxy. Among the identified extragalactic sources, the large majority (14) is made up of type 1 AGNs (i.e. with broad emission lines); of these, 6 lie at redshift larger than 0.5 and one (IGR J12319-0749) has z = 3.12, which makes it the second farthest object detected in the INTEGRAL surveys up to now. The remaining AGNs are of type 2 (that is, with narrow emission lines only), and one of the two cases is confirmed as a pair of interacting Seyfert 2 galaxies. The Galactic objects are identified as two cataclysmic variables, one high-mass X-ray binary, one symbiotic binary and two chromospherically active stars, possibly of RS CVn type. The main physical parameters of these hard X-ray sources were also determined using the multiwavelength information available in the literature. We thus still find that AGNs are the most abundant population among hard X-ray objects identified through optical spectroscopy. Moreover, we note that the higher sensitivity of the more recent INTEGRAL surveys is now enabling the detection of high-redshift AGNs, thus allowing the exploration of the most distant hard X-ray emitting sources and possibly of the most extreme blazars. Based on observations collected at the following observatories: Cerro Tololo Interamerican Observatory (Chile); Observatorio del Roque de los Muchachos of the Instituto de Astrofísica de Canarias (Canary Islands, Spain); Astronomical Observatory of Bologna in Loiano (Italy); Astronomical Observatory of Asiago (Italy); Observatorio Astronómico Nacional (San Pedro Mártir, Mexico); Anglo-Australian Observatory (Siding Spring, Australia).

Masetti, N.; Parisi, P.; Jiménez-Bailón, E.; Palazzi, E.; Chavushyan, V.; Bassani, L.; Bazzano, A.; Bird, A. J.; Dean, A. J.; Galaz, G.; Landi, R.; Malizia, A.; Minniti, D.; Morelli, L.; Schiavone, F.; Stephen, J. B.; Ubertini, P.

2012-02-01

383

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

384

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

385

Methods development for diffraction and spectroscopy studies of metalloenzymes at X-ray free-electron lasers.  

PubMed

X-ray free-electron lasers (XFELs) open up new possibilities for X-ray crystallographic and spectroscopic studies of radiation-sensitive biological samples under close to physiological conditions. To facilitate these new X-ray sources, tailored experimental methods and data-processing protocols have to be developed. The highly radiation-sensitive photosystem II (PSII) protein complex is a prime target for XFEL experiments aiming to study the mechanism of light-induced water oxidation taking place at a Mn cluster in this complex. We developed a set of tools for the study of PSII at XFELs, including a new liquid jet based on electrofocusing, an energy dispersive von Hamos X-ray emission spectrometer for the hard X-ray range and a high-throughput soft X-ray spectrometer based on a reflection zone plate. While our immediate focus is on PSII, the methods we describe here are applicable to a wide range of metalloenzymes. These experimental developments were complemented by a new software suite, cctbx.xfel. This software suite allows for near-real-time monitoring of the experimental parameters and detector signals and the detailed analysis of the diffraction and spectroscopy data collected by us at the Linac Coherent Light Source, taking into account the specific characteristics of data measured at an XFEL. PMID:24914169

Kern, Jan; Hattne, Johan; Tran, Rosalie; Alonso-Mori, Roberto; Laksmono, Hartawan; Gul, Sheraz; Sierra, Raymond G; Rehanek, Jens; Erko, Alexei; Mitzner, Rolf; Wernet, Phillip; Bergmann, Uwe; Sauter, Nicholas K; Yachandra, Vittal; Yano, Junko

2014-07-17

386

Low-Dimensional Water on Ru(0001)Model System for X-ray Absorption Spectroscopy Studies of Liquid Water  

SciTech Connect

We present an x-ray absorption spectroscopy results for fully broken to a complete H-bond network of water molecules on Ru(0001) by varying the morphology from isolated water molecules via two-dimensional clusters to a fully covered monolayer as probed by scanning tunneling microscopy. The sensitivity of x-ray absorption to the symmetry of H-bonding is further elucidated for the amino (-NH{sub 2}) group in glycine adsorbed on Cu(110) where the E-vector is parallel either to the NH donating an H-bond or to the non-H-bonded NH. The results give further evidence for the interpretation of the various spectral features of liquid water and for the general applicability of x-ray absorption spectroscopy to analyze H-bonded systems.

Nordlund, D

2012-02-14

387

High Resolution X-Ray Spectroscopy of the Local Hot Gas along the 3C 273 Sightline  

NASA Astrophysics Data System (ADS)

X-ray observations of highly ionized metal absorption lines at z = 0 provide critical information on the hot gas distribution in and around the Milky Way. We present a study of more than 10 yr of Chandra and XMM-Newton observations of 3C 273, one of the brightest extragalactic X-ray sources. Compared with previous works, we obtain much tighter constraints on the physical properties of the X-ray absorber. We also find a large, non-thermal velocity at ~100-150 km s-1, the main reason for the higher line equivalent width when compared with other sightlines. Using joint analysis with X-ray emission and ultraviolet observations, we derive a size of 5-15 kpc and a temperature of (1.5-1.8) × 106 K for the X-ray absorber. The 3C 273 sightline passes through a number of Galactic structures, including radio loops I and IV, the North Polar Spur, and the neighborhood of the newly discovered "Fermi bubbles." We argue that the X-ray absorber is unlikely to be associated with the nearby radio loops I and IV; however, the non-thermal velocity can be naturally explained as the result of the expansion of the "Fermi bubbles." Our data imply a shock-expansion velocity of 200-300 km s-1. Our study indicates a likely complex environment for the production of the Galactic X-ray absorbers along different sightlines, and highlights the significance of probing galactic feedback with high resolution X-ray spectroscopy.

Fang, Taotao; Jiang, Xiaochuan

2014-04-01

388

Application of X-ray Absorption Spectroscopy to the study of nuclear structural materials  

NASA Astrophysics Data System (ADS)

One of key technologies for the next generation nuclear systems are advanced materials, including high temperature structural materials, fast neutron resistance core materials and so on. Local structure determination in these systems, which often are crystallographically intractable, is critical to gaining an understanding of their properties. In this thesis, X-ray Absorption Spectroscopy (XAS), including Extended X-ray Absorption Fine Structure (EXAFS) and X-ray Absorption Near Edge Structure (XANES), is used to examine the geometric and electronic structure of nuclear structural materials under varying conditions. The thesis is divided into two main sections. The first examines the structural analysis of nanostructured ferritic alloys (NFA) which are dispersion strengthened by an ultra high density of Y-Ti-O enriched nano-features, resulting in remarkable high temperature creep strength and radiation damage resistance. Titanium and Yttrium K-edge XAS shows commercial alloys MA957 and J12YWT more closely resemble the as received Fe-14Cr-3W-0.4Ti (wt. %) powders, and mechanically alloyed (MA) powders with 0.25Y2O3 (wt. %). It shows that a significant fraction of substitutional Ti remains dissolved in the (BCC) ferrite matrix. In contrast, annealed powders and hot isostatic press (HIP) consolidated alloys show high temperature heat treatments shift the Y and Ti to more oxidized states that are consistent with combinations of Y2Ti2O7 and, especially, TiO. The second section describes corrosion studies of Pb with 316L stainless steel, molybdenum and spinet (MgAl2O4) at high temperature by XAS. The corrosion of fuel cladding and structural materials by liquid lead at elevated temperatures is an issue that must be considered when designing advanced nuclear systems and high-power spallation neutron targets. The results of ex-situ studies show that a Mo substrate retained a smooth and less corroded surface than 316L stainless steel sample at elevated temperature. In-situ XAS is used to investigate the interaction layer of Pb corrosion on a molybdenum substrate as a function of temperature. The Pb layer deposited by thermal evaporation is 3-6 gm thick. The EXAFS and XANES data show similar trends with the qualitative appearance and disappearance of a short distance peak (EXAFS) and the quantitative signature of the MoO3 moiety (XANES) in the intermediate temperature range of 650-800°C.

Liu, Shanshan

389

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

390

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

391

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

PubMed

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, UO2(2+) (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 (<0.3 mol % U, <1 microM U(VI) in solution), U(VI) is present as a strong bidentate surface complex. At high concentrations (>2 mol % U, >4 microM 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. PMID:16509317

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

2006-02-01

392

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

393

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

394

THREE NEW GALACTIC CENTER X-RAY SOURCES IDENTIFIED WITH NEAR-INFRARED SPECTROSCOPY  

SciTech Connect

We have conducted a near-infrared spectroscopic survey of 47 candidate counterparts to X-ray sources discovered by the Chandra X-Ray Observatory near the Galactic center (GC). Though a significant number of these astrometric matches are likely to be spurious, we sought out spectral characteristics of active stars and interacting binaries, such as hot, massive spectral types or emission lines, in order to corroborate the X-ray activity and certify the authenticity of the match. We present three new spectroscopic identifications, including a Be high-mass X-ray binary (HMXB) or a ? Cassiopeiae (Cas) system, a symbiotic X-ray binary, and an O-type star of unknown luminosity class. The Be HMXB/? Cas system and the symbiotic X-ray binary are the first of their classes to be spectroscopically identified in the GC region.

DeWitt, Curtis [Department of Physics, University of California, Davis, CA 95616 (United States); Bandyopadhyay, Reba M.; Eikenberry, Stephen S.; Sarajedini, Ata [Department of Astronomy, University of Florida, 211 Bryant Space Center, P.O. Box 112055, Gainesville, FL 32611 (United States); Sellgren, Kris [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Blum, Robert; Olsen, Knut [National Optical Astronomy Observatories, Tucson, AZ 85719 (United States); Bauer, Franz E., E-mail: curtis.n.dewitt@nasa.gov [Departamento de Astronomía y Astrofísica, Pontificia Universidad Católica de Chile, Casilla 306, Santiago 22 (Chile)

2013-11-01

395

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

396

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

397

Performance assessment of patient dosimetry services and X-ray quality assurance instruments used in diagnostic radiology  

Microsoft Academic Search

Experiences of the Regional Radiation Physics and Protection Service (RRPPS) in performance assessment of diagnostic X-ray QA instrumentation and on-patient dosemeters are recounted. Issues relating to the provision of realistic and reproducible reference conditions for calibrated X-irradiations are considered and summary statistics from test measurements of dose and kVp meters are provided. For both dose and kVp meters it is

S. Green; J. E. Palethorpe; D. Peach; D. A. Bradley

1999-01-01

398

X-ray flux concentrating optics for improving the performance of light element energy dispersive spectroscopy  

Microsoft Academic Search

Frequently, EDS (Energy Dispersive Spectrometer) x-ray detectors cannot be placed very close to an x-ray source for microanalysis causing the detector to subtend a small solid angle thus reducing the available count rate. This is exacerbated by low count rates for the light elements and situations where low energy spectral lines are immersed in a background of higher energy x-rays

David B. O'Hara

1998-01-01

399

Evaluation of sorption of uranium onto metakaolin using X-ray photoelectron and Raman spectroscopies.  

PubMed

Metakaolin prepared from a natural clay mineral ore of aluminium kaolinite is a promising low cost and high activity aluminosilicate material that has been investigated for studying the sorption behavior of uranium. Here, metakaolin was characterized using X-ray photoelectron spectroscopy (XPS) and the effects of pH, contact time and initial metal ion concentration on its sorption behavior were studied. The sorption process was found to initially be rapid (approximately 60% at time 0 min) but became slower with time; equilibrium was established within 24 h (approximately 80% sorption). The data were applied to study the kinetics of the sorption process. The Langmuir and Dubinin-Radushkevich (D-R) sorption isotherms were used to describe partitioning behavior for the system at room temperature. The binding of metal ions was found to be pH dependent, with optimal sorption occurring at pH 5. The retained metal ions were eluted with 5 mL of 0.1 M HNO(3). Raman spectroscopy and XPS were used to evaluate the sorption mechanism of U(VI). PMID:19046680

Memon, Jamil R; Hallam, Keith R; Bhanger, Muhammad I; El-Turki, Adel; Allen, Geoffrey C

2009-01-01

400

Structures of bromoalkanes' photodissociation in solution by means of ultrafast extended x-ray absorption fine-structure spectroscopy  

PubMed Central

The structures of initial and final products of bromoalkanes' photodisociation reaction in cyclohexane solution have been measured with a bond length accuracy of 0.02 ? by means of ultrafast time-resolved extended x-ray absorption fine structure spectroscopy. The photoredaction mechanism is also discussed. PMID:12239341

Oulianov, D. A.; Tomov, I. V.; Dvornikov, A. S.; Rentzepis, P. M.

2002-01-01

401

X-RAY SPECTROSCOPY OF THE UNSTEADY QUIESCENT CORONA OF AD LEONIS WITH CHANDRA A. Maggio,1  

E-print Network

that the EMD is compatible with the model of a corona continuously heated by flares, which predicts an EMD structures that confine hot plasma in stellar coronae and the nature of coronal heating. The topologyX-RAY SPECTROSCOPY OF THE UNSTEADY QUIESCENT CORONA OF AD LEONIS WITH CHANDRA A. Maggio,1 J. J

Micela, Giusi

402

Corrosion protection of iron\\/steel by emeraldine base polyaniline: an X-ray photoelectron spectroscopy study  

Microsoft Academic Search

The emeraldine base form of polyaniline has been used as a corrosion protecting undercoat on steel and iron samples. Using X-ray photoelectron spectroscopy, the anti-corrosion performance of various application methods of the emeraldine base layer was studied, as well as the mechanism for corrosion protection. Emeraldine base polyaniline undercoats were found to offer corrosion protection for both the cold rolled

M. Fahlman; S. Jasty; A. J. Epstein

1997-01-01

403

Microscopic chemical state identification of a silicon-carbide fiber by soft x-ray photoabsorption spectroscopy  

Microsoft Academic Search

Chemical states of a 140 ?m silicon carbide fiber are determined by soft x-ray photo-absorption spectroscopy, using a magnetic projection photoelectron microscope, performed on the surface obtained by fracturing. The spectrum of the carbon core of the fiber has prominent ?* and ?* resonance peaks and is very similar to that measured on highly oriented pyrolitic graphite, indicating a graphitic

Qing Ma; Richard A. Rosenberg; Changyoung Kim; Jostein Grepstad; Piero Pianetta

1997-01-01

404

Toward a Complete Metrological Solution for the Mirrors for the Constellation-X Spectroscopy X-ray Telescope  

NASA Technical Reports Server (NTRS)

We present an overview update of the metrological approach to be employed for the segmented mirror fabrication for Constellation-X spectroscopy x-ray telescope. We compare results achieved to date with mission requirements. This is discussed in terms of inherent capability versus in-practice capability.

Lehan, John; Owens, S.; Hadjimichael, T.; Hong, M.; Chan, K.-W.; Saha, T. T.; Reid, P.; Zhang, W. W.

2007-01-01

405

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

Microsoft Academic Search

X-ray absorption spectroscopy (XAS) affords the opportunity to probe the atomic environment of trace elements in human bone. We are using XAS to investigate the mode(s) of incorporation of Sr, Zn, Pb, and Ba in both modern and ancient (and thus possibly altered) human and animal bone. Because burial and diagenesis may add trace elements to bone, we performed XAS

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

2001-01-01

406

X-ray spectroscopy in mammography with a silicon PIN photodiode with application to the measurement of tube voltage  

Microsoft Academic Search

In this work a silicon PIN photodiode was employed in mammographic x-ray spectroscopy under clinical and nonclinical conditions. Measurements have been performed at a constant potential tungsten anode tube, adapted in this work with molybdenum filters to produce a beam like that used in mammography, and at a clinical equipment with a molybdenum anode tube by using an additional aluminum

Roseli Kuenzel; Silvio Bruni Herdade; Ricardo Andrade Terini; Paulo Roberto Costa

2004-01-01

407

Probing Reaction Dynamics of Transition-Metal Complexes in Solution via Time-Resolved Soft X-ray Spectroscopy  

SciTech Connect

We report the first time-resolved soft x-ray measurements of solvated transition-metal complexes. L-edge spectroscopy directly probes dynamic changes in ligand-field splitting of 3d orbitals associated with the spin transition, and mediated by changes in ligand-bonding.

Huse, Nils; Kim, Tae Kyu; Khalil, Munira; Jamula, Lindsey; McCusker, James K.; Schoenlein, Robert W.

2010-05-02

408

A vacuum double-crystal spectrometer for reference-free highly charged ions X-ray spectroscopy  

E-print Network

of elements ranging from hydrogen to uranium. For medium atomic number elements, relevant to x-ray reflection of parts per million range have been obtained. Beam-foil spectroscopy has been employed to provide (25 ppm), germanium5 and krypton.6,7 The main limitation to obtain high accuracy in Beam-foil

Paris-Sud XI, Université de

409

Communications: Near edge x-ray absorption fine structure spectroscopy of aqueous adenosine triphosphate at the carbon and nitrogen  

E-print Network

Communications: Near edge x-ray absorption fine structure spectroscopy of aqueous adenosine and carbon K-edges was used to study the hydration of adenosine triphosphate in liquid microjets. The total of adenosine triphosphate ATP to the corresponding diphosphate is able to thermodynamically drive many

Cohen, Ronald C.

410

First-principles core-level X-ray photoelectron spectroscopy calculation on arsenic defects in silicon crystal  

NASA Astrophysics Data System (ADS)

We investigate the X-ray photoelectron spectroscopy (XPS) binding energies of As 3d in Si for various defects in neutral and charged states by first-principles calculation. It is found that the complexes of a substitutional As and a vacancy in charged and neutral states explain the experimentally observed unknown peak very well.

Kishi, Hiroki; Miyazawa, Miki; Matsushima, Naoki; Yamauchi, Jun

2014-02-01

411

In situ study of an oxidation reaction on a Pt/C electrode by ambient pressure hard X-ray photoelectron spectroscopy  

NASA Astrophysics Data System (ADS)

We have constructed an ambient pressure X-ray photoelectron spectroscopy instrument that uses hard X-ray radiation at the high-performance undulator beamline BL36XU of SPring-8. The dependence of the Au 4f peak intensity from Au foil on the ambient N2 pressure was measured. At a photon energy of 7.94 keV, the Au 4f peak intensity maintained 40% at 3000 Pa compared with that at high vacuum. We designed a polymer electrolyte fuel cell that allows us to perform X-ray photoelectron spectroscopy measurements of an electrode under working conditions. The oxidized Pt peaks were observed in the Pt 3d5/2 level of Pt nanoparticles in the cathode, and the peaks clearly depended on the applied voltage between the anode and cathode. Our apparatus can be applied as a valuable in situ tool for the investigation of the electronic states and adsorbed species of polymer electrolyte fuel cell electrode catalysts under the reaction conditions.

Takagi, Yasumasa; Wang, Heng; Uemura, Yohei; Ikenaga, Eiji; Sekizawa, Oki; Uruga, Tomoya; Ohashi, Haruhiko; Senba, Yasunori; Yumoto, Hirokatsu; Yamazaki, Hiroshi; Goto, Shunji; Tada, Mizuki; Iwasawa, Yasuhiro; Yokoyama, Toshihiko

2014-09-01

412

Lithium extraction\\/insertion in LiFePO 4: an X-ray diffraction and Mössbauer spectroscopy study  

Microsoft Academic Search

The extraction and insertion of lithium in solid-state synthesized LiFePO4 has been followed by in situ X-ray diffraction and Mössbauer spectroscopy in ‘coffee-bag’ cells of type ?Li-metal | liq. el. | LiFePO4? during the first cycle. Two-phase Rietveld refinement of the X-ray diffractograms gives the triphylite (LiFePO4) to heterosite (FePO4) phase-ratios as charging and discharging of the cell proceeds. The

Anna S Andersson; Beata Kalska; Lennart Häggström; John O Thomas

2000-01-01

413

A study of ancient pottery by means of X-ray fluorescence spectroscopy, multivariate statistics and mineralogical analysis.  

PubMed

Energy-dispersive X-ray fluorescence spectroscopy was used to determine the composition of 64 potsherds from the Hellenistic settlement of Orraon, in northwestern Greece. Data classification by principal components analysis revealed four distinct groups of pottery, pointing to different local production practices rather than different provenance. The interpretation of statistical grouping was corroborated by a complementary X-ray diffraction analysis. Compositional and mineralogical data, combined with archaeological and materials' science criteria, allowed addressing various aspects of pottery making, such as selection of raw clays, tempers and firing conditions. PMID:17723544

Papachristodoulou, Christina; Oikonomou, Artemios; Ioannides, Kostas; Gravani, Konstantina

2006-07-28

414

Mechanical and Thermal Analysis of the Spectroscopy X-ray Telescopes for the Constellation-X Mission  

NASA Technical Reports Server (NTRS)

Area and mass requirements for the Constellation-X Spectroscopy X-Ray Telescopes restrict the thickness of the mirror segment to below a mm. Requirement of angular resolution of 15" over the soft x-ray band implies that allowable optic deformation is sub-micrometer for these thin segments. These requirements place stringent constraint on the mounting, alignment and affixing of these mirror segments in both the metrology and integration processes. We present analyses and optimization of the Constellation-X mirrors under relevant mechanical and thermal environments.

Chan, Kai-Wing; Bolognese, Jeffrey; Saha, Timo; Sturm, James; Zhang, William

2007-01-01

415

Site-selective high-resolution X-ray absorption spectroscopy and high-resolution X-ray emission spectroscopy of cobalt nanoparticles.  

PubMed

The special (macroscopic) properties of nanoparticles are mainly due to their large surface-to-volume ratio. Thus, the separate characterization of geometric and electronic properties of surface and bulk would be favorable for a better understanding of the properties of nanoparticles. Because of the chemical sensitivity of X-ray fluorescence lines, in particular those involving higher lying electronic states, high-resolution fluorescence-detected X-ray absorption spectra (HRFD-XAS) offer these opportunities. In this study, three types of wet-chemically synthesized Co nanoparticles, ?6 nm in diameter with varying thicknesses of a protective shell, were investigated at the ID26 beamline of the European Synchrotron Radiation Facility. HRFD-XAS spectra at the Co K-edge, that is, X-ray absorption near-edge structure (HRFD-XANES) and extended X-ray absorption fine structure (HRFD-EXAFS) spectra, were recorded via detection of the K?1,3 fluorescence at specific energies. As these spectra are only pa