Sample records for x-ray solution scattering

  1. Resonant soft X-ray scattering on protein solutions

    NASA Astrophysics Data System (ADS)

    Ye, Dan; Le, Thinh; Wang, Cheng; Zwart, Peter; Gomez, Esther; Gomez, Enrique

    Protein structure is crucial for biological function, such that characterizing protein folding and packing is important for the design of therapeutics and enzymes. We propose resonant soft X-ray scattering (RSOXS) as an approach to study proteins and other biological assemblies in solution. Calculations of the scattering contrast suggest that soft X-ray scattering is more sensitive than hard X-ray scattering, because of contrast generated at the absorption edges of constituent elements such as carbon, nitrogen and oxygen. We have examined the structure of bovine serum albumin (BSA) in solution by RSOXS. We find that by varying incident X-ray energies, we are able to achieve higher scattering contrast near the absorption edge. From our RSOXS scattering result we are able to reconstruct the structure of BSA in 3D. These RSOXS results also agree with hard X-ray experiments, including crystallographic data. Our study demonstrates the potential of RSOXS for studying protein structure in solution.

  2. Reconstruction of viruses from solution x-ray scattering data

    NASA Astrophysics Data System (ADS)

    Zheng, Yibin; Doerschuk, Peter C.; Johnson, John E.

    1995-08-01

    A model-based method for reconstructing the 3D structure of icosahedrally-symmetric viruses from solution x-ray scattering is presented. An example of the reconstruction, for data from cowpea mosaic virus, is described. The major opportunity provided by solution x-ray scattering is the ability to study the dynamics of virus particles in solution, information that is not accessible to crystal x-ray diffraction experiments.

  3. Small Angle X-Ray Scattering from Lipid-Bound Myelin Basic Protein in Solution

    PubMed Central

    Haas, H.; Oliveira, C. L. P.; Torriani, I. L.; Polverini, E.; Fasano, A.; Carlone, G.; Cavatorta, P.; Riccio, P.

    2004-01-01

    The structure of myelin basic protein (MBP), purified from the myelin sheath in both lipid-free (LF-MBP) and lipid-bound (LB-MBP) forms, was investigated in solution by small angle x-ray scattering. The water-soluble LF-MBP, extracted at pH < 3.0 from defatted brain, is the classical preparation of MBP, commonly regarded as an intrinsically unfolded protein. LB-MBP is a lipoprotein-detergent complex extracted from myelin with its native lipidic environment at pH > 7.0. Under all conditions, the scattering from the two protein forms was different, indicating different molecular shapes. For the LB-MBP, well-defined scattering curves were obtained, suggesting that the protein had a unique, compact (but not globular) structure. Furthermore, these data were compatible with earlier results from molecular modeling calculations on the MBP structure which have been refined by us. In contrast, the LF-MBP data were in accordance with the expected open-coil conformation. The results represent the first direct structural information from x-ray scattering measurements on MBP in its native lipidic environment in solution. PMID:14695288

  4. X-ray scattering study

    NASA Technical Reports Server (NTRS)

    Wriston, R. S.; Froechtenigt, J. F.

    1972-01-01

    A soft X-ray glancing incidence telescope mirror and a group of twelve optical flat samples were used to study the scattering of X-rays. The mirror was made of Kanigen coated beryllium and the images produced were severely limited by scattering of X-rays. The best resolution attained was about fifteen arc seconds. The telescope efficiency was found to be 0.0006. The X-ray beam reflected from the twelve optical flat samples was analyzed by means of a long vacuum system of special design for these tests. The scattering then decreased with increasing angle of incidence until a critical angle was passed. At larger angles the scattering increased again. The samples all scattered more at 44 A than at 8 A. Metal samples were found to have about the same scattering at 44 A but greater scattering at 8 A than glass samples.

  5. Protein structural dynamics in solution unveiled via 100-ps time-resolved x-ray scattering.

    PubMed

    Cho, Hyun Sun; Dashdorj, Naranbaatar; Schotte, Friedrich; Graber, Timothy; Henning, Robert; Anfinrud, Philip

    2010-04-20

    We have developed a time-resolved x-ray scattering diffractometer capable of probing structural dynamics of proteins in solution with 100-ps time resolution. This diffractometer, developed on the ID14B BioCARS (Consortium for Advanced Radiation Sources) beamline at the Advanced Photon Source, records x-ray scattering snapshots over a broad range of q spanning 0.02-2.5 A(-1), thereby providing simultaneous coverage of the small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) regions. To demonstrate its capabilities, we have tracked structural changes in myoglobin as it undergoes a photolysis-induced transition from its carbon monoxy form (MbCO) to its deoxy form (Mb). Though the differences between the MbCO and Mb crystal structures are small (rmsd < 0.2 A), time-resolved x-ray scattering differences recorded over 8 decades of time from 100 ps to 10 ms are rich in structure, illustrating the sensitivity of this technique. A strong, negative-going feature in the SAXS region appears promptly and corresponds to a sudden > 22 A(3) volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume approximately 2 A(3) larger than MbCO within approximately 10 ns. On the timescale for CO escape from the primary docking site, another change in the SAXS/WAXS fingerprint appears, demonstrating sensitivity to the location of the dissociated CO. Global analysis of the SAXS/WAXS patterns recovered time-independent scattering fingerprints for four intermediate states of Mb. These SAXS/WAXS fingerprints provide stringent constraints for putative models of conformational states and structural transitions between them.

  6. Protein structural dynamics in solution unveiled via 100-ps time-resolved x-ray scattering

    PubMed Central

    Anfinrud, Philip

    2010-01-01

    We have developed a time-resolved x-ray scattering diffractometer capable of probing structural dynamics of proteins in solution with 100-ps time resolution. This diffractometer, developed on the ID14B BioCARS (Consortium for Advanced Radiation Sources) beamline at the Advanced Photon Source, records x-ray scattering snapshots over a broad range of q spanning 0.02–2.5 Å-1, thereby providing simultaneous coverage of the small-angle x-ray scattering (SAXS) and wide-angle x-ray scattering (WAXS) regions. To demonstrate its capabilities, we have tracked structural changes in myoglobin as it undergoes a photolysis-induced transition from its carbon monoxy form (MbCO) to its deoxy form (Mb). Though the differences between the MbCO and Mb crystal structures are small (rmsd < 0.2 Å), time-resolved x-ray scattering differences recorded over 8 decades of time from 100 ps to 10 ms are rich in structure, illustrating the sensitivity of this technique. A strong, negative-going feature in the SAXS region appears promptly and corresponds to a sudden > 22 Å3 volume expansion of the protein. The ensuing conformational relaxation causes the protein to contract to a volume ∼2 Å3 larger than MbCO within ∼10 ns. On the timescale for CO escape from the primary docking site, another change in the SAXS/WAXS fingerprint appears, demonstrating sensitivity to the location of the dissociated CO. Global analysis of the SAXS/WAXS patterns recovered time-independent scattering fingerprints for four intermediate states of Mb. These SAXS/WAXS fingerprints provide stringent constraints for putative models of conformational states and structural transitions between them. PMID:20406909

  7. Assessment study of ion-exchange chromatography combined with solution X-ray scattering measurement for protein characterization.

    PubMed

    Watanabe, Yasushi

    2018-03-02

    The performance of ion-exchange chromatography combined with small-angle X-ray scattering measurement was evaluated by characterization of the hen egg white lysozyme as a model protein. The X-ray transmittance was estimated using a micro-ionization chamber equipped with a sample cell holder for the real-time monitoring of the X-ray beam strength through the salt gradient elution. The radius of gyration of the eluted protein was estimated to be 1.50 ± 0.06 (n = 3) nm and 1.4 ± 0.1 nm as the value at the zero protein concentration. By using the X-ray transmittance values for the scattering intensity correction, the molecular weight of the eluted protein was estimated to be 15,200 ± 500 (n = 3) and 14,400 ± 200 as the value at the zero protein concentration. These values are close to those of the monomer of this protein. The ion-exchange chromatography combined with the small-angle X-ray scattering measurement system equipped with the X-ray transmittance monitor is a reliable method for protein characterization in solution. Copyright © 2018 Elsevier B.V. All rights reserved.

  8. Stimulated Electronic X-Ray Raman Scattering

    NASA Astrophysics Data System (ADS)

    Weninger, Clemens; Purvis, Michael; Ryan, Duncan; London, Richard A.; Bozek, John D.; Bostedt, Christoph; Graf, Alexander; Brown, Gregory; Rocca, Jorge J.; Rohringer, Nina

    2013-12-01

    We demonstrate strong stimulated inelastic x-ray scattering by resonantly exciting a dense gas target of neon with femtosecond, high-intensity x-ray pulses from an x-ray free-electron laser (XFEL). A small number of lower energy XFEL seed photons drive an avalanche of stimulated resonant inelastic x-ray scattering processes that amplify the Raman scattering signal by several orders of magnitude until it reaches saturation. Despite the large overall spectral width, the internal spiky structure of the XFEL spectrum determines the energy resolution of the scattering process in a statistical sense. This is demonstrated by observing a stochastic line shift of the inelastically scattered x-ray radiation. In conjunction with statistical methods, XFELs can be used for stimulated resonant inelastic x-ray scattering, with spectral resolution smaller than the natural width of the core-excited, intermediate state.

  9. Anisotropy enhanced X-ray scattering from solvated transition metal complexes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Biasin, Elisa; van Driel, Tim B.; Levi, Gianluca

    Time-resolved X-ray scattering patterns from photoexcited molecules in solution are in many cases anisotropic at the ultrafast time scales accessible at X-ray free-electron lasers (XFELs). This anisotropy arises from the interaction of a linearly polarized UV–Vis pump laser pulse with the sample, which induces anisotropic structural changes that can be captured by femtosecond X-ray pulses. In this work, a method for quantitative analysis of the anisotropic scattering signal arising from an ensemble of molecules is described, and it is demonstrated how its use can enhance the structural sensitivity of the time-resolved X-ray scattering experiment. This method is applied on time-resolvedmore » X-ray scattering patterns measured upon photoexcitation of a solvated di-platinum complex at an XFEL, and the key parameters involved are explored. Here it is shown that a combined analysis of the anisotropic and isotropic difference scattering signals in this experiment allows a more precise determination of the main photoinduced structural change in the solute,i.e.the change in Pt—Pt bond length, and yields more information on the excitation channels than the analysis of the isotropic scattering only. Finally, it is discussed how the anisotropic transient response of the solvent can enable the determination of key experimental parameters such as the instrument response function.« less

  10. Anisotropy enhanced X-ray scattering from solvated transition metal complexes

    DOE PAGES

    Biasin, Elisa; van Driel, Tim B.; Levi, Gianluca; ...

    2018-02-13

    Time-resolved X-ray scattering patterns from photoexcited molecules in solution are in many cases anisotropic at the ultrafast time scales accessible at X-ray free-electron lasers (XFELs). This anisotropy arises from the interaction of a linearly polarized UV–Vis pump laser pulse with the sample, which induces anisotropic structural changes that can be captured by femtosecond X-ray pulses. In this work, a method for quantitative analysis of the anisotropic scattering signal arising from an ensemble of molecules is described, and it is demonstrated how its use can enhance the structural sensitivity of the time-resolved X-ray scattering experiment. This method is applied on time-resolvedmore » X-ray scattering patterns measured upon photoexcitation of a solvated di-platinum complex at an XFEL, and the key parameters involved are explored. Here it is shown that a combined analysis of the anisotropic and isotropic difference scattering signals in this experiment allows a more precise determination of the main photoinduced structural change in the solute,i.e.the change in Pt—Pt bond length, and yields more information on the excitation channels than the analysis of the isotropic scattering only. Finally, it is discussed how the anisotropic transient response of the solvent can enable the determination of key experimental parameters such as the instrument response function.« less

  11. Experimental Approaches for Solution X-Ray Scattering and Fiber Diffraction

    PubMed Central

    Irving, T. C.

    2008-01-01

    X-ray scattering and diffraction from non-crystalline systems have gained renewed interest in recent years, as focus shifts from the structural chemistry information gained by high-resolution studies to the context of structural physiology at larger length scales. Such techniques permit the study of isolated macromolecules as well as highly organized macromolecular assemblies as a whole under near-physiological conditions. Time-resolved approaches, made possible by advanced synchrotron instrumentation, add a critical dimension to many of these investigations. This article reviews experimental approaches in non-crystalline x-ray scattering and diffraction that may be used to illuminate important scientific questions such as protein/nucleic acid folding and structure-function relationships in large macromolecular assemblies. PMID:18801437

  12. Tracking reaction dynamics in solution by pump-probe X-ray absorption spectroscopy and X-ray liquidography (solution scattering).

    PubMed

    Kim, Jeongho; Kim, Kyung Hwan; Oang, Key Young; Lee, Jae Hyuk; Hong, Kiryong; Cho, Hana; Huse, Nils; Schoenlein, Robert W; Kim, Tae Kyu; Ihee, Hyotcherl

    2016-03-07

    Characterization of transient molecular structures formed during chemical and biological processes is essential for understanding their mechanisms and functions. Over the last decade, time-resolved X-ray liquidography (TRXL) and time-resolved X-ray absorption spectroscopy (TRXAS) have emerged as powerful techniques for molecular and electronic structural analysis of photoinduced reactions in the solution phase. Both techniques make use of a pump-probe scheme that consists of (1) an optical pump pulse to initiate a photoinduced process and (2) an X-ray probe pulse to monitor changes in the molecular structure as a function of time delay between pump and probe pulses. TRXL is sensitive to changes in the global molecular structure and therefore can be used to elucidate structural changes of reacting solute molecules as well as the collective response of solvent molecules. On the other hand, TRXAS can be used to probe changes in both local geometrical and electronic structures of specific X-ray-absorbing atoms due to the element-specific nature of core-level transitions. These techniques are complementary to each other and a combination of the two methods will enhance the capability of accurately obtaining structural changes induced by photoexcitation. Here we review the principles of TRXL and TRXAS and present recent application examples of the two methods for studying chemical and biological processes in solution. Furthermore, we briefly discuss the prospect of using X-ray free electron lasers for the two techniques, which will allow us to keep track of structural dynamics on femtosecond time scales in various solution-phase molecular reactions.

  13. The life science X-ray scattering beamline at NSLS-II

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    DiFabio, Jonathan; Yang, Lin; Chodankar, Shirish

    We report the current development status of the High Brightness X-ray Scattering for Life Sciences (or Life Science X-ray Scattering, LiX) beamline at the NSLS-II facility of Brookhaven National Laboratory. This instrument will operate in the x-ray energy range of 2.1-18 keV, provide variable beam sizes from 1 micron to ~0.5 mm, and support user experiments in three scientific areas: (1) high-throughput solution scattering, in-line size exclusion chromatography and flow mixers-based time-resolved solution scattering of biological macro-molecules, (2) diffraction from single- and multi-layered lipid membranes, and (3) scattering-based scanning probe imaging of biological tissues. In order to satisfy the beammore » stability required for these experiments and to switch rapidly between different types of experiments, we have adopted a secondary source with refractive lenses for secondary focusing, a detector system consisting of three Pilatus detectors, and specialized experimental modules that can be quickly exchanged and each dedicated to a defined set of experiments. The construction of this beamline is on schedule for completion in September 2015. User experiments are expected to start in Spring 2016.« less

  14. The life science X-ray scattering beamline at NSLS-II

    DOE PAGES

    DiFabio, Jonathan; Yang, Lin; Chodankar, Shirish; ...

    2015-09-30

    We report the current development status of the High Brightness X-ray Scattering for Life Sciences (or Life Science X-ray Scattering, LiX) beamline at the NSLS-II facility of Brookhaven National Laboratory. This instrument will operate in the x-ray energy range of 2.1-18 keV, provide variable beam sizes from 1 micron to ~0.5 mm, and support user experiments in three scientific areas: (1) high-throughput solution scattering, in-line size exclusion chromatography and flow mixers-based time-resolved solution scattering of biological macro-molecules, (2) diffraction from single- and multi-layered lipid membranes, and (3) scattering-based scanning probe imaging of biological tissues. In order to satisfy the beammore » stability required for these experiments and to switch rapidly between different types of experiments, we have adopted a secondary source with refractive lenses for secondary focusing, a detector system consisting of three Pilatus detectors, and specialized experimental modules that can be quickly exchanged and each dedicated to a defined set of experiments. The construction of this beamline is on schedule for completion in September 2015. User experiments are expected to start in Spring 2016.« less

  15. The life science x-ray scattering beamline at NSLS-II

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    DiFabio, Jonathan; Chodankar, Shirish; Pjerov, Sal

    We report the current development status of the High Brightness X-ray Scattering for Life Sciences (or Life Science X-ray Scattering, LiX) beamline at the NSLS-II facility of Brookhaven National Laboratory. This instrument will operate in the x-ray energy range of 2.1-18 keV, provide variable beam sizes from 1 micron to ∼0.5 mm, and support user experiments in three scientific areas: (1) high-throughput solution scattering, in-line size exclusion chromatography and flow mixers-based time-resolved solution scattering of biological macro-molecules, (2) diffraction from single- and multi-layered lipid membranes, and (3) scattering-based scanning probe imaging of biological tissues. In order to satisfy the beammore » stability required for these experiments and to switch rapidly between different types of experiments, we have adopted a secondary source with refractive lenses for secondary focusing, a detector system consisting of three Pilatus detectors, and specialized experimental modules that can be quickly exchanged and each dedicated to a defined set of experiments. The construction of this beamline is on schedule for completion in September 2015. User experiments are expected to start in Spring 2016.« less

  16. Polarized x-ray excitation for scatter reduction in x-ray fluorescence computed tomography.

    PubMed

    Vernekohl, Don; Tzoumas, Stratis; Zhao, Wei; Xing, Lei

    2018-05-25

    X-ray fluorescence computer tomography (XFCT) is a new molecular imaging modality which uses x-ray excitation to stimulate the emission of fluorescent photons in high atomic number contrast agents. Scatter contamination is one of the main challenges in XFCT imaging which limits the molecular sensitivity. When polarized x rays are used, it is possible to reduce the scatter contamination significantly by placing detectors perpendicular to the polarization direction. This study quantifies scatter contamination for polarized and unpolarized x-ray excitation and determines the advantages of scatter reduction. The amount of scatter in preclinical XFCT is quantified in Monte Carlo simulations. The fluorescent x rays are emitted isotropically, while scattered x rays propagate in polarization direction. The magnitude of scatter contamination is studied in XFCT simulations of a mouse phantom. In this study, the contrast agent gold is examined as an example, but a scatter reduction from polarized excitation is also expected for other elements. The scatter reduction capability is examined for different polarization intensities with a monoenergetic x-ray excitation energy of 82 keV. The study evaluates two different geometrical shapes of CZT detectors which are modeled with an energy resolution of 1 keV FWHM at an x-ray energy of 80 keV. Benefits of a detector placement perpendicular to the polarization direction are shown in iterative and analytic image reconstruction including scatter correction. The contrast to noise ratio (CNR) and the normalized mean square error (NMSE) are analyzed and compared for the reconstructed images. A substantial scatter reduction for common detector sizes was achieved for 100% and 80% linear polarization while lower polarization intensities provide a decreased scatter reduction. By placing the detector perpendicular to the polarization direction, a scatter reduction by factor up to 5.5 can be achieved for common detector sizes. The image

  17. Small Angle X-Ray Scattering Detector

    DOEpatents

    Hessler, Jan P.

    2004-06-15

    A detector for time-resolved small-angle x-ray scattering includes a nearly constant diameter, evacuated linear tube having an end plate detector with a first fluorescent screen and concentric rings of first fiber optic bundles for low angle scattering detection and an annular detector having a second fluorescent screen and second fiber optic bundles concentrically disposed about the tube for higher angle scattering detection. With the scattering source, i.e., the specimen under investigation, located outside of the evacuated tube on the tube's longitudinal axis, scattered x-rays are detected by the fiber optic bundles, to each of which is coupled a respective photodetector, to provide a measurement resolution, i.e., dq/q, where q is the momentum transferred from an incident x-ray to an x-ray scattering specimen, of 2% over two (2) orders of magnitude in reciprocal space, i.e., q.sub.max /q.sub.min.congruent.100.

  18. X-ray scattering data and structural genomics

    NASA Astrophysics Data System (ADS)

    Doniach, Sebastian

    2003-03-01

    High throughput structural genomics has the ambitious goal of determining the structure of all, or a very large number of protein folds using the high-resolution techniques of protein crystallography and NMR. However, the program is facing significant bottlenecks in reaching this goal, which include problems of protein expression and crystallization. In this talk, some preliminary results on how the low-resolution technique of small-angle X-ray solution scattering (SAXS) can help ameliorate some of these bottlenecks will be presented. One of the most significant bottlenecks arises from the difficulty of crystallizing integral membrane proteins, where only a handful of structures are available compared to thousands of structures for soluble proteins. By 3-dimensional reconstruction from SAXS data, the size and shape of detergent-solubilized integral membrane proteins can be characterized. This information can then be used to classify membrane proteins which constitute some 25% of all genomes. SAXS may also be used to study the dependence of interparticle interference scattering on solvent conditions so that regions of the protein solution phase diagram which favor crystallization can be elucidated. As a further application, SAXS may be used to provide physical constraints on computational methods for protein structure prediction based on primary sequence information. This in turn can help in identifying structural homologs of a given protein, which can then give clues to its function. D. Walther, F. Cohen and S. Doniach. "Reconstruction of low resolution three-dimensional density maps from one-dimensional small angle x-ray scattering data for biomolecules." J. Appl. Cryst. 33(2):350-363 (2000). Protein structure prediction constrained by solution X-ray scattering data and structural homology identification Zheng WJ, Doniach S JOURNAL OF MOLECULAR BIOLOGY , v. 316(#1) pp. 173-187 FEB 8, 2002

  19. Complementary uses of small angle X-ray scattering and X-ray crystallography.

    PubMed

    Pillon, Monica C; Guarné, Alba

    2017-11-01

    Most proteins function within networks and, therefore, protein interactions are central to protein function. Although stable macromolecular machines have been extensively studied, dynamic protein interactions remain poorly understood. Small-angle X-ray scattering probes the size, shape and dynamics of proteins in solution at low resolution and can be used to study samples in a large range of molecular weights. Therefore, it has emerged as a powerful technique to study the structure and dynamics of biomolecular systems and bridge fragmented information obtained using high-resolution techniques. Here we review how small-angle X-ray scattering can be combined with other structural biology techniques to study protein dynamics. This article is part of a Special Issue entitled: Biophysics in Canada, edited by Lewis Kay, John Baenziger, Albert Berghuis and Peter Tieleman. Copyright © 2017 Elsevier B.V. All rights reserved.

  20. X-ray crystal structure and small-angle X-ray scattering of sheep liver sorbitol dehydrogenase

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yennawar, Hemant; Møller, Magda; University of Copenhagen, DK-2100 Copenhagen

    The X-ray crystal structure and a small-angle X-ray scattering solution structure of sheep liver sorbitol dehydrogenase have been determined. The details of the interactions that enable the tetramer scaffold to be the functional biological unit have been analyzed. The X-ray crystal structure of sheep liver sorbitol dehydrogenase (slSDH) has been determined using the crystal structure of human sorbitol dehydrogenase (hSDH) as a molecular-replacement model. slSDH crystallized in space group I222 with one monomer in the asymmetric unit. A conserved tetramer that superposes well with that seen in hSDH (despite belonging to a different space group) and obeying the 222 crystalmore » symmetry is seen in slSDH. An acetate molecule is bound in the active site, coordinating to the active-site zinc through a water molecule. Glycerol, a substrate of slSDH, also occupies the substrate-binding pocket together with the acetate designed by nature to fit large polyol substrates. The substrate-binding pocket is seen to be in close proximity to the tetramer interface, which explains the need for the structural integrity of the tetramer for enzyme activity. Small-angle X-ray scattering was also used to identify the quaternary structure of the tetramer of slSDH in solution.« less

  1. Resonant soft X-ray scattering for polymer materials

    DOE PAGES

    Liu, Feng; Brady, Michael A.; Wang, Cheng

    2016-04-16

    Resonant Soft X-ray Scattering (RSoXS) was developed within the last few years, and the first dedicated resonant soft X-ray scattering beamline for soft materials was constructed at the Advanced Light Source, LBNL. RSoXS combines soft X-ray spectroscopy with X-ray scattering and thus offers statistical information for 3D chemical morphology over a large length scale range from nanometers to micrometers. Using RSoXS to characterize multi-length scale soft materials with heterogeneous chemical structures, we have demonstrated that soft X-ray scattering is a unique complementary technique to conventional hard X-ray and neutron scattering. Its unique chemical sensitivity, large accessible size scale, molecular bondmore » orientation sensitivity with polarized X-rays, and high coherence have shown great potential for chemically specific structural characterization for many classes of materials.« less

  2. X-ray Scattering Combined with Coordinate-Based Analyses for Applications in Natural and Artificial Photosynthesis

    PubMed Central

    Tiede, David M.; Mardis, Kristy L.; Zuo, Xiaobing

    2009-01-01

    Advances in x-ray light sources and detectors have created opportunities for advancing our understanding of structure and structural dynamics for supramolecular assemblies in solution by combining x-ray scattering measurement with coordinate-based modeling methods. In this review the foundations for x-ray scattering are discussed and illustrated with selected examples demonstrating the ability to correlate solution x-ray scattering measurements to molecular structure, conformation, and dynamics. These approaches are anticipated to have a broad range of applications in natural and artificial photosynthesis by offering possibilities for structure resolution for dynamic supramolecular assemblies in solution that can not be fully addressed with crystallographic techniques, and for resolving fundamental mechanisms for solar energy conversion by mapping out structure in light-excited reaction states. PMID:19636808

  3. Crystal defect studies using x-ray diffuse scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Larson, B.C.

    1980-01-01

    Microscopic lattice defects such as point (single atom) defects, dislocation loops, and solute precipitates are characterized by local electronic density changes at the defect sites and by distortions of the lattice structure surrounding the defects. The effect of these interruptions of the crystal lattice on the scattering of x-rays is considered in this paper, and examples are presented of the use of the diffuse scattering to study the defects. X-ray studies of self-interstitials in electron irradiated aluminum and copper are discussed in terms of the identification of the interstitial configuration. Methods for detecting the onset of point defect aggregation intomore » dislocation loops are considered and new techniques for the determination of separate size distributions for vacancy loops and interstitial loops are presented. Direct comparisons of dislocation loop measurements by x-rays with existing electron microscopy studies of dislocation loops indicate agreement for larger size loops, but x-ray measurements report higher concentrations in the smaller loop range. Methods for distinguishing between loops and three-dimensional precipitates are discussed and possibilities for detailed studies considered. A comparison of dislocation loop size distributions obtained from integral diffuse scattering measurements with those from TEM show a discrepancy in the smaller sizes similar to that described above.« less

  4. Heterodyne x-ray diffuse scattering from coherent phonons

    DOE PAGES

    Kozina, M.; Trigo, M.; Chollet, M.; ...

    2017-08-10

    Here in this paper, we report Fourier-transform inelastic x-ray scattering measurements of photoexcited GaAs with embedded ErAs nanoparticles. We observe temporal oscillations in the x-ray scattering intensity, which we attribute to inelastic scattering from coherent acoustic phonons. Unlike in thermal equilibrium, where inelastic x-ray scattering is proportional to the phonon occupation, we show that the scattering is proportional to the phonon amplitude for coherent states. The wavevectors of the observed phonons extend beyond the excitation wavevector. The nanoparticles break the discrete translational symmetry of the lattice, enabling the generation of large wavevector coherent phonons. Elastic scattering of x-ray photons frommore » the nanoparticles provides a reference for heterodyne mixing, yielding signals proportional to the phonon amplitude.« less

  5. Upgrade of MacCHESS facility for X-ray scattering of biological macromolecules in solution

    PubMed Central

    Acerbo, Alvin Samuel; Cook, Michael J.; Gillilan, Richard Edward

    2015-01-01

    X-ray scattering of biological macromolecules in solution is an increasingly popular tool for structural biology and benefits greatly from modern high-brightness synchrotron sources. The upgraded MacCHESS BioSAXS station is now located at the 49-pole wiggler beamline G1. The 20-fold improved flux over the previous beamline F2 provides higher sample throughput and autonomous X-ray scattering data collection using a unique SAXS/WAXS dual detectors configuration. This setup achieves a combined q-range from 0.007 to 0.7 Å−1, enabling better characterization of smaller molecules, while opening opportunities for emerging wide-angle scattering methods. In addition, a facility upgrade of the positron storage ring to continuous top-up mode has improved beam stability and eliminated beam drift over the course of typical BioSAXS experiments. Single exposure times have been reduced to 2 s for 3.560 mg ml−1 lysozyme with an average quality factor I/σ of 20 in the Guinier region. A novel disposable plastic sample cell design that incorporates lower background X-ray window material provides users with a more pristine sample environment than previously available. Systematic comparisons of common X-ray window materials bonded to the cell have also been extended to the wide-angle regime, offering new insight into best choices for various q-space ranges. In addition, a quantitative assessment of signal-to-noise levels has been performed on the station to allow users to estimate necessary exposure times for obtaining usable signals in the Guinier regime. Users also have access to a new BioSAXS sample preparation laboratory which houses essential wet-chemistry equipment and biophysical instrumentation. User experiments at the upgraded BioSAXS station have been on-going since commissioning of the beamline in Summer 2013. A planned upgrade of the G1 insertion device to an undulator for the Winter 2014 cycle is expected to further improve flux by an order of magnitude. PMID

  6. Investigation of the structure of unilamellar dimyristoylphosphatidylcholine vesicles in aqueous sucrose solutions by small-angle neutron and X-ray scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kiselev, M. A., E-mail: elena@jinr.ru; Zemlyanaya, E. V.; Zhabitskaya, E. I.

    2015-01-15

    The structure of a polydispersed population of unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles in sucrose solutions has been investigated by small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Calculations within the model of separated form factors (SFF) show that the structure of the vesicle system depends strongly on the sucrose concentration.

  7. X-ray solution scattering combined with computation characterizing protein folds and multiple conformational states : computation and application.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, S.; Park, S.; Makowski, L.

    Small angle X-ray scattering (SAXS) is an increasingly powerful technique to characterize the structure of biomolecules in solution. We present a computational method for accurately and efficiently computing the solution scattering curve from a protein with dynamical fluctuations. The method is built upon a coarse-grained (CG) representation of the protein. This CG approach takes advantage of the low-resolution character of solution scattering. It allows rapid determination of the scattering pattern from conformations extracted from CG simulations to obtain scattering characterization of the protein conformational landscapes. Important elements incorporated in the method include an effective residue-based structure factor for each aminomore » acid, an explicit treatment of the hydration layer at the surface of the protein, and an ensemble average of scattering from all accessible conformations to account for macromolecular flexibility. The CG model is calibrated and illustrated to accurately reproduce the experimental scattering curve of Hen egg white lysozyme. We then illustrate the computational method by calculating the solution scattering pattern of several representative protein folds and multiple conformational states. The results suggest that solution scattering data, when combined with a reliable computational method, have great potential for a better structural description of multi-domain complexes in different functional states, and for recognizing structural folds when sequence similarity to a protein of known structure is low. Possible applications of the method are discussed.« less

  8. Small Angle X-ray Scattering for Nanoparticle Research

    DOE PAGES

    Li, Tao; Senesi, Andrew J.; Lee, Byeongdu

    2016-04-07

    X-ray scattering is a structural characterization tool that has impacted diverse fields of study. It is unique in its ability to examine materials in real time and under realistic sample environments, enabling researchers to understand morphology at nanometer and ångström length scales using complementary small and wide angle X-ray scattering (SAXS, WAXS), respectively. Herein, we focus on the use of SAXS to examine nanoscale particulate systems. We provide a theoretical foundation for X-ray scattering, considering both form factor and structure factor, as well as the use of correlation functions, which may be used to determine a particle’s size, size distribution,more » shape, and organization into hierarchal structures. The theory is expanded upon with contemporary use cases. Both transmission and reflection (grazing incidence) geometries are addressed, as well the combination of SAXS with other X-ray and non-X ray characterization tools. Furthermore, we conclude with an examination of several key areas of research where X-rays scattering has played a pivotal role, including in situ nanoparticle synthesis, nanoparticle assembly, and in operando studies of catalysts and energy storage materials. Throughout this review we highlight the unique capabilities of X-ray scattering for structural characterization of materials in their native environment.« less

  9. Small Angle X-ray Scattering for Nanoparticle Research

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Tao; Senesi, Andrew J.; Lee, Byeongdu

    X-ray scattering is a structural characterization tool that has impacted diverse fields of study. It is unique in its ability to examine materials in real time and under realistic sample environments, enabling researchers to understand morphology at nanometer and ångström length scales using complementary small and wide angle X-ray scattering (SAXS, WAXS), respectively. Herein, we focus on the use of SAXS to examine nanoscale particulate systems. We provide a theoretical foundation for X-ray scattering, considering both form factor and structure factor, as well as the use of correlation functions, which may be used to determine a particle’s size, size distribution,more » shape, and organization into hierarchal structures. The theory is expanded upon with contemporary use cases. Both transmission and reflection (grazing incidence) geometries are addressed, as well the combination of SAXS with other X-ray and non-X ray characterization tools. Furthermore, we conclude with an examination of several key areas of research where X-rays scattering has played a pivotal role, including in situ nanoparticle synthesis, nanoparticle assembly, and in operando studies of catalysts and energy storage materials. Throughout this review we highlight the unique capabilities of X-ray scattering for structural characterization of materials in their native environment.« less

  10. Robust, high-throughput solution structural analyses by small angle X-ray scattering (SAXS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hura, Greg L.; Menon, Angeli L.; Hammel, Michal

    2009-07-20

    We present an efficient pipeline enabling high-throughput analysis of protein structure in solution with small angle X-ray scattering (SAXS). Our SAXS pipeline combines automated sample handling of microliter volumes, temperature and anaerobic control, rapid data collection and data analysis, and couples structural analysis with automated archiving. We subjected 50 representative proteins, mostly from Pyrococcus furiosus, to this pipeline and found that 30 were multimeric structures in solution. SAXS analysis allowed us to distinguish aggregated and unfolded proteins, define global structural parameters and oligomeric states for most samples, identify shapes and similar structures for 25 unknown structures, and determine envelopes formore » 41 proteins. We believe that high-throughput SAXS is an enabling technology that may change the way that structural genomics research is done.« less

  11. X-ray scattering signatures of β-thalassemia

    NASA Astrophysics Data System (ADS)

    Desouky, Omar S.; Elshemey, Wael M.; Selim, Nabila S.

    2009-08-01

    X-ray scattering from lyophilized proteins or protein-rich samples is characterized by the presence of two characteristic broad peaks at scattering angles equivalent to momentum transfer values of 0.27 and 0.6 nm -1, respectively. These peaks arise from the interference of coherently scattered photons. Once the conformation of a protein is changed, these two peaks reflect such change with considerable sensitivity. The present work examines the possibility of characterizing the most common cause of hemolytic anaemia in Egypt and many Mediterranean countries; β-thalassemia, from its X-ray scattering profile. This disease emerges from a genetic defect causing reduced rate in the synthesis of one of the globin chains that make up hemoglobin. As a result, structurally abnormal hemoglobin molecules are formed. In order to detect such molecular disorder, hemoglobin samples of β-thalassemia patients are collected, lyophilized and measured using a conventional X-ray diffractometer. Results show significant differences in the X-ray scattering profiles of most of the diseased samples compared to control. The shape of the first scattering peak at 0.27 nm -1, in addition to the relative intensity of the first to the second scattering peaks, provides the most reliable signs of abnormality in diseased samples. The results are interpreted and confirmed with the aid of Fourier Transform Infrared (FTIR) spectroscopy of normal and thalassemia samples.

  12. Stimulated resonant x-ray Raman scattering with incoherent radiation

    NASA Astrophysics Data System (ADS)

    Weninger, Clemens; Rohringer, Nina

    2013-11-01

    We present a theoretical study on stimulated electronic Raman scattering in neon by resonant excitation with an x-ray free electron laser (XFEL). This study is in support of the recent experimental demonstration [C. Weninger , Phys. Rev. Lett. (to be published)] of stimulated x-ray Raman scattering. Focusing the broadband XFEL pulses into a cell of neon gas at atmospheric pressure a strong inelastic x-ray scattering signal in the forward direction was observed, as the x-ray energy was varied across the region of core-excited Rydberg states and the K edge. The broadband and intrinsically incoherent x-ray pulses from the XFEL lead to a rich, structured line shape of the scattered radiation. We present a generalized Maxwell-Liouville-von Neumann approach to self-consistently solve for the amplification of the scattered radiation along with the time evolution of the density matrix of the atomic and residual ionic system. An in-depth analysis of the evolution of the emission spectra as a function of the Raman gain is presented. Furthermore, we propose the use of statistical methods to obtain high-resolution scattering data beyond the lifetime broadening despite pumping with incoherent x-ray pulses.

  13. Healing X-ray scattering images

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Jiliang; Lhermitte, Julien; Tian, Ye

    X-ray scattering images contain numerous gaps and defects arising from detector limitations and experimental configuration. Here, we present a method to heal X-ray scattering images, filling gaps in the data and removing defects in a physically meaningful manner. Unlike generic inpainting methods, this method is closely tuned to the expected structure of reciprocal-space data. In particular, we exploit statistical tests and symmetry analysis to identify the structure of an image; we then copy, average and interpolate measured data into gaps in a way that respects the identified structure and symmetry. Importantly, the underlying analysis methods provide useful characterization of structuresmore » present in the image, including the identification of diffuseversussharp features, anisotropy and symmetry. The presented method leverages known characteristics of reciprocal space, enabling physically reasonable reconstruction even with large image gaps. The method will correspondingly fail for images that violate these underlying assumptions. The method assumes point symmetry and is thus applicable to small-angle X-ray scattering (SAXS) data, but only to a subset of wide-angle data. Our method succeeds in filling gaps and healing defects in experimental images, including extending data beyond the original detector borders.« less

  14. Healing X-ray scattering images

    DOE PAGES

    Liu, Jiliang; Lhermitte, Julien; Tian, Ye; ...

    2017-05-24

    X-ray scattering images contain numerous gaps and defects arising from detector limitations and experimental configuration. Here, we present a method to heal X-ray scattering images, filling gaps in the data and removing defects in a physically meaningful manner. Unlike generic inpainting methods, this method is closely tuned to the expected structure of reciprocal-space data. In particular, we exploit statistical tests and symmetry analysis to identify the structure of an image; we then copy, average and interpolate measured data into gaps in a way that respects the identified structure and symmetry. Importantly, the underlying analysis methods provide useful characterization of structuresmore » present in the image, including the identification of diffuseversussharp features, anisotropy and symmetry. The presented method leverages known characteristics of reciprocal space, enabling physically reasonable reconstruction even with large image gaps. The method will correspondingly fail for images that violate these underlying assumptions. The method assumes point symmetry and is thus applicable to small-angle X-ray scattering (SAXS) data, but only to a subset of wide-angle data. Our method succeeds in filling gaps and healing defects in experimental images, including extending data beyond the original detector borders.« less

  15. Incoherent-scatter computed tomography with monochromatic synchrotron x ray: feasibility of multi-CT imaging system for simultaneous measurement-of fluorescent and incoherent scatter x rays

    NASA Astrophysics Data System (ADS)

    Yuasa, T.; Akiba, M.; Takeda, T.; Kazama, M.; Hoshino, A.; Watanabe, Y.; Hyodo, K.; Dilmanian, F. A.; Akatsuka, T.; Itai, Y.

    1997-10-01

    We describe a new system of incoherent scatter computed tomography (ISCT) using monochromatic synchrotron X rays, and we discuss its potential to be used in in vivo imaging for medical use. The system operates on the basis of computed tomography (CT) of the first generation. The reconstruction method for ISCT uses the least squares method with singular value decomposition. The research was carried out at the BLNE-5A bending magnet beam line of the Tristan Accumulation Ring in KEK, Japan. An acrylic cylindrical phantom of 20-mm diameter containing a cross-shaped channel was imaged. The channel was filled with a diluted iodine solution with a concentration of 200 /spl mu/gI/ml. Spectra obtained with the system's high purity germanium (HPGe) detector separated the incoherent X-ray line from the other notable peaks, i.e., the iK/sub /spl alpha// and K/sub /spl beta/1/ X-ray fluorescent lines and the coherent scattering peak. CT images were reconstructed from projections generated by integrating the counts In the energy window centering around the incoherent scattering peak and whose width was approximately 2 keV. The reconstruction routine employed an X-ray attenuation correction algorithm. The resulting image showed more homogeneity than one without the attenuation correction.

  16. Instrumentation on Multi-Scaled Scattering of Bio-Macromolecular Solutions

    PubMed Central

    Chu, Benjamin; Fang, Dufei; Mao, Yimin

    2015-01-01

    The design, construction and initial tests on a combined laser light scattering and synchrotron X-ray scattering instrument can cover studies of length scales from atomic sizes in Angstroms to microns and dynamics from microseconds to seconds are presented. In addition to static light scattering (SLS), dynamic light scattering (DLS), small angle X-ray scattering (SAXS) and wide angle X-ray diffraction (WAXD), the light scattering instrument is being developed to carry out studies in mildly turbid solutions, in the presence of multiple scattering. Three-dimensional photon cross correlation function (3D-PCCF) measurements have been introduced to couple with synchrotron X-ray scattering to study the structure, size and dynamics of macromolecules in solution. PMID:25946340

  17. Coherent X-ray Scattering from Liquid-Air Interfaces

    NASA Astrophysics Data System (ADS)

    Shpyrko, Oleg

    Advances in synchrotron x-ray scattering techniques allow studies of structure and dynamics of liquid surfaces with unprecedented resolution. I will review x-ray scattering measurements of thermally excited capillary fluctuations in liquids, thin polymer liquid films and polymer surfaces in confined geometry. X-ray Diffuse scattering profile due to Debye-Waller like roughening of the surface allows to probe the distribution of capillary fluctuations over a wide range of length scales, while using X-ray Photon Correlation Spectroscopy (XPCS) one is able to directly couple to nanoscale dynamics of these surface fluctuations, over a wide range of temporal and spacial scales. I will also discuss recent XPCS measurements of lateral diffusion dynamics in Langmuir monolayers assembled at the liquid-air interface. This research was supported by NSF CAREER Grant 0956131.

  18. Protein hydration in solution: Experimental observation by x-ray and neutron scattering

    PubMed Central

    Svergun, D. I.; Richard, S.; Koch, M. H. J.; Sayers, Z.; Kuprin, S.; Zaccai, G.

    1998-01-01

    The structure of the protein–solvent interface is the subject of controversy in theoretical studies and requires direct experimental characterization. Three proteins with known atomic resolution crystal structure (lysozyme, Escherichia coli thioredoxin reductase, and protein R1 of E. coli ribonucleotide reductase) were investigated in parallel by x-ray and neutron scattering in H2O and D2O solutions. The analysis of the protein–solvent interface is based on the significantly different contrasts for the protein and for the hydration shell. The results point to the existence of a first hydration shell with an average density ≈10% larger than that of the bulk solvent in the conditions studied. Comparisons with the results of other studies suggest that this may be a general property of aqueous interfaces. PMID:9482874

  19. Operational properties of fluctuation X-ray scattering data

    DOE PAGES

    Malmerberg, Erik; Kerfeld, Cheryl A.; Zwart, Petrus H.

    2015-03-20

    X-ray scattering images collected on timescales shorter than rotation diffusion times using a (partially) coherent beam result in a significant increase in information content in the scattered data. These measurements, named fluctuation X-ray scattering (FXS), are typically performed on an X-ray free-electron laser (XFEL) and can provide fundamental insights into the structure of biological molecules, engineered nanoparticles or energy-related mesoscopic materials beyond what can be obtained with standard X-ray scattering techniques. In order to understand, use and validate experimental FXS data, the availability of basic data characteristics and operational properties is essential, but has been absent up to this point.more » In this communication, an intuitive view of the nature of FXS data and their properties is provided, the effect of FXS data on the derived structural models is highlighted, and generalizations of the Guinier and Porod laws that can ultimately be used to plan experiments and assess the quality of experimental data are presented.« less

  20. Scatter of X-rays on polished surfaces

    NASA Technical Reports Server (NTRS)

    Hasinger, G.

    1981-01-01

    In investigating the dispersion properties of telescope mirrors used in X-ray astronomy, the slight scattering characteristics of X-ray radiation by statistically rough surfaces were examined. The mathematics and geometry of scattering theory are described. The measurement test assembly is described and results of measurements on samples of plane mirrors are given. Measurement results are evaluated. The direct beam, the convolution of the direct beam and the scattering halo, curve fitting by the method of least squares, various autocorrelation functions, results of the fitting procedure for small scattering, and deviations in the kernel of the scattering distribution are presented. A procedure for quality testing of mirror systems through diagnosis of rough surfaces is described.

  1. High performance x-ray anti-scatter grid

    DOEpatents

    Logan, Clinton M.

    1995-01-01

    An x-ray anti-scatter grid for x-ray imaging, particularly for screening mammography, and method for fabricating same, x-rays incident along a direct path pass through a grid composed of a plurality of parallel or crossed openings, microchannels, grooves, or slots etched in a substrate, such as silicon, having the walls of the microchannels or slots coated with a high opacity material, such as gold, while x-rays incident at angels with respect to the slots of the grid, arising from scatter, are blocked. The thickness of the substrate is dependent on the specific application of the grid, whereby a substrate of the grid for mammography would be thinner than one for chest radiology. Instead of coating the walls of the slots, such could be filed with an appropriate liquid, such as mercury.

  2. Structure of aqueous cesium metaborate solutions by X-ray scattering and DFT calculation

    NASA Astrophysics Data System (ADS)

    Zhang, W. Q.; Fang, C. H.; Fang, Y.; Zhu, F. Y.; Zhou, Y. Q.; Liu, H. Y.; Li, W.

    2018-05-01

    In the present work, precise radial distribution function (RDF) of cesium metaborate solutions with salt-water molar ratio of 1:25, 1:30 and 1:35 in large scattering vector range (3.91-214.26 nm-1) were obtained by X-ray scattering. Polyborate species were given using Newton iteration method with measured pH and literature equilibrium constants. In model calculation, structural parameters such as the coordination number, interatomic distance and Debye-Waller factor were given through model calculation. The B-O(H2O) distance was determined to be ∼0.37 nm with the hydration number of ∼7.8 for B(OH)4-. The Cs-B distance of the contact ions CsB(OH)40 was measured to be ∼0.46 nm with interaction number of ∼0.77. The interaction distances and coordination number for the first shell and the second shell of Cs-O(W) are ∼0.325 nm, ∼0.517 nm and ∼8.0, ∼11, respectively. Five low-energy configurations of [Cs(H2O)8]+ were given with DFT calculation, including the first and the second hydration shell, and the most stable eight-coordinated one is close to the model calculation. Furthermore, the effect of concentration is discussed in the X-ray scattering analysis part, showing that hydration degree changes with the concentration. For the coordination number and distance of Cs-O(H2O) and H-bonding decrease with the increasing concentration. The coordination number of Cs-O(H2O) keep stable, and the coordination distance changes from 3.25 nm to 3.30 nm. For H-bonding, which the coordination number varies from 2.20 to 2.24, and the coordination distance varies from 2.76 nm to 2.78 nm with the decreasing concentration.

  3. High performance x-ray anti-scatter grid

    DOEpatents

    Logan, C.M.

    1995-05-23

    Disclosed are an x-ray anti-scatter grid for x-ray imaging, particularly for screening mammography, and method for fabricating same, x-rays incident along a direct path pass through a grid composed of a plurality of parallel or crossed openings, microchannels, grooves, or slots etched in a substrate, such as silicon, having the walls of the microchannels or slots coated with a high opacity material, such as gold, while x-rays incident at angels with respect to the slots of the grid, arising from scatter, are blocked. The thickness of the substrate is dependent on the specific application of the grid, whereby a substrate of the grid for mammography would be thinner than one for chest radiology. Instead of coating the walls of the slots, such could be filed with an appropriate liquid, such as mercury. 4 Figs.

  4. Generation of first hard X-ray pulse at Tsinghua Thomson Scattering X-ray Source.

    PubMed

    Du, Yingchao; Yan, Lixin; Hua, Jianfei; Du, Qiang; Zhang, Zhen; Li, Renkai; Qian, Houjun; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

    2013-05-01

    Tsinghua Thomson Scattering X-ray Source (TTX) is the first-of-its-kind dedicated hard X-ray source in China based on the Thomson scattering between a terawatt ultrashort laser and relativistic electron beams. In this paper, we report the experimental generation and characterization of the first hard X-ray pulses (51.7 keV) via head-on collision of an 800 nm laser and 46.7 MeV electron beams. The measured yield is 1.0 × 10(6) per pulse with an electron bunch charge of 200 pC and laser pulse energy of 300 mJ. The angular intensity distribution and energy spectra of the X-ray pulse are measured with an electron-multiplying charge-coupled device using a CsI scintillator and silicon attenuators. These measurements agree well with theoretical and simulation predictions. An imaging test using the X-ray pulse at the TTX is also presented.

  5. Studying Dust Scattering Halos with Galactic X-ray Binaries

    NASA Astrophysics Data System (ADS)

    Beeler, Doreen; Corrales, Lia; Heinz, Sebastian

    2018-01-01

    Dust is an important part of the interstellar medium (ISM) and contributes to the formation of stars and planets. Since the advent of modern X-ray telescopes, Galactic X-ray point sources have permitted a closer look at all phases of the ISM. Interstellar metals from oxygen to iron — in both gas and dust form — are responsible for absorption and scattering of X-ray light. Dust scatters the light in a forward direction and creates a diffuse halo image surrounding many bright Galactic X-ray binaries. We use all the bright X-ray point sources available in the Chandra HETG archive to study dust scattering halos from the local ISM. We have described a data analysis pipeline using a combination of the data reduction software CIAO and Python. We compare our results from Chandra HETG and ACIS-I observations of a well studied dust scattering halo around GX 13+1, in order to characterize any systematic errors associated with the HETG data set. We describe how our data products will be used to measure ISM scaling relations for X-ray extinction, dust abundance, and dust-to-metal ratios.

  6. DNA conformations in mismatch repair probed in solution by X-ray scattering from gold nanocrystals

    PubMed Central

    Hura, Greg L.; Tsai, Chi-Lin; Claridge, Shelley A.; Mendillo, Marc L.; Smith, Jessica M.; Williams, Gareth J.; Mastroianni, Alexander J.; Alivisatos, A. Paul; Putnam, Christopher D.; Kolodner, Richard D.; Tainer, John A.

    2013-01-01

    DNA metabolism and processing frequently require transient or metastable DNA conformations that are biologically important but challenging to characterize. We use gold nanocrystal labels combined with small angle X-ray scattering to develop, test, and apply a method to follow DNA conformations acting in the Escherichia coli mismatch repair (MMR) system in solution. We developed a neutral PEG linker that allowed gold-labeled DNAs to be flash-cooled and stored without degradation in sample quality. The 1,000-fold increased gold nanocrystal scattering vs. DNA enabled investigations at much lower concentrations than otherwise possible to avoid concentration-dependent tetramerization of the MMR initiation enzyme MutS. We analyzed the correlation scattering functions for the nanocrystals to provide higher resolution interparticle distributions not convoluted by the intraparticle distribution. We determined that mispair-containing DNAs were bent more by MutS than complementary sequence DNA (csDNA), did not promote tetramer formation, and allowed MutS conversion to a sliding clamp conformation that eliminated the DNA bends. Addition of second protein responder MutL did not stabilize the MutS-bent forms of DNA. Thus, DNA distortion is only involved at the earliest mispair recognition steps of MMR: MutL does not trap bent DNA conformations, suggesting migrating MutL or MutS/MutL complexes as a conserved feature of MMR. The results promote a mechanism of mismatch DNA bending followed by straightening in initial MutS and MutL responses in MMR. We demonstrate that small angle X-ray scattering with gold labels is an enabling method to examine protein-induced DNA distortions key to the DNA repair, replication, transcription, and packaging. PMID:24101514

  7. X-ray and Neutron Scattering Study of the Formation of Core–Shell-Type Polyoxometalates

    DOE PAGES

    Yin, Panchao; Wu, Bin; Mamontov, Eugene; ...

    2016-02-05

    A typical type of core-shell polyoxometalates can be obtained through the Keggin-type polyoxometalate-templated growth of a layer of spherical shell structure of {Mo 72Fe 30}. Small angle X-ray scattering is used to study the structural features and stability of the core-shell structures in aqueous solutions. Time-resolved small angle X-ray scattering is applied to monitor the synthetic reactions and a three-stage formation mechanism is proposed to describe the synthesis of the core-shell polyoxometalates based on the monitoring results. Quasi-elastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core-shell structures and two different types ofmore » water molecules, the confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures. A typical type of core shell polyoxometalates can be obtained through the Keggin-type polyoxometalate-templated growth of a layer of spherical shell structure of {Mo 72Fe 30}. Small-angle X-ray scattering is used to study the structural features and stability of the core shell structures in aqueous solutions. Time-resolved small-angle X-ray scattering is applied to monitor the synthetic reactions, and a three-stage formation mechanism is proposed to describe the synthesis of the core shell polyoxometalates based on the monitoring results. New protocols have been developed by fitting the X-ray data with custom physical models, which provide more convincing, objective, and completed data interpretation. Quasi-elastic and inelastic neutron scattering are used to probe the dynamics of water molecules in the core shell structures, and two different types of water molecules, the confined and structured water, are observed. These water molecules play an important role in bridging core and shell structures and stabilizing the cluster structures.« less

  8. X-Ray Scattering Echoes and Ghost Halos from the Intergalactic Medium: Relation to the Nature of AGN Variability

    NASA Astrophysics Data System (ADS)

    Corrales, Lia

    2015-05-01

    X-ray bright quasars might be used to trace dust in the circumgalactic and intergalactic medium through the phenomenon of X-ray scattering, which is observed around Galactic objects whose light passes through a sufficient column of interstellar gas and dust. Of particular interest is the abundance of gray dust larger than 0.1 μ m, which is difficult to detect at other wavelengths. To calculate X-ray scattering from large grains, one must abandon the traditional Rayleigh-Gans approximation. The Mie solution for the X-ray scattering optical depth of the universe is ∼ 1%. This presents a great difficulty for distinguishing dust scattered photons from the point source image of Chandra, which is currently unsurpassed in imaging resolution. The variable nature of AGNs offers a solution to this problem, as scattered light takes a longer path and thus experiences a time delay with respect to non-scattered light. If an AGN dims significantly (≳ 3 dex) due to a major feedback event, the Chandra point source image will be suppressed relative to the scattering halo, and an X-ray echo or ghost halo may become visible. I estimate the total number of scattering echoes visible by Chandra over the entire sky: {{N}ech}∼ {{10}3}({{ν }fb}/y{{r}-1}), where {{ν }fb} is the characteristic frequency of feedback events capable of dimming an AGN quickly.

  9. X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study

    NASA Astrophysics Data System (ADS)

    Inkinen, Juho; Niskanen, Johannes; Talka, Tuomas; Sahle, Christoph J.; Müller, Harald; Khriachtchev, Leonid; Hashemi, Javad; Akbari, Ali; Hakala, Mikko; Huotari, Simo

    2015-11-01

    A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering.

  10. Dynamical scattering in coherent hard x-ray nanobeam Bragg diffraction

    NASA Astrophysics Data System (ADS)

    Pateras, A.; Park, J.; Ahn, Y.; Tilka, J. A.; Holt, M. V.; Kim, H.; Mawst, L. J.; Evans, P. G.

    2018-06-01

    Unique intensity features arising from dynamical diffraction arise in coherent x-ray nanobeam diffraction patterns of crystals having thicknesses larger than the x-ray extinction depth or exhibiting combinations of nanoscale and mesoscale features. We demonstrate that dynamical scattering effects can be accurately predicted using an optical model combined with the Darwin theory of dynamical x-ray diffraction. The model includes the highly divergent coherent x-ray nanobeams produced by Fresnel zone plate focusing optics and accounts for primary extinction, multiple scattering, and absorption. The simulation accurately reproduces the dynamical scattering features of experimental diffraction patterns acquired from a GaAs/AlGaAs epitaxial heterostructure on a GaAs (001) substrate.

  11. Small-angle x-ray scattering study of polymer structure: Carbosilane dendrimers in hexane solution

    NASA Astrophysics Data System (ADS)

    Shtykova, E. V.; Feigin, L. A.; Volkov, V. V.; Malakhova, Yu. N.; Streltsov, D. R.; Buzin, A. I.; Chvalun, S. N.; Katarzhanova, E. Yu.; Ignatieva, G. M.; Muzafarov, A. M.

    2016-09-01

    The three-dimensional organization of monodisperse hyper-branched macromolecules of regular structure—carbosilane dendrimers of zero, third, and sixth generations—has been studied by small-angle X-ray scattering (SAXS) in solution. The use of modern methods of SAXS data interpretation, including ab initio modeling, has made it possible to determine the internal architecture of the dendrimers in dependence of the generation number and the number of cyclosiloxane end groups (forming the shell of dendritic macromolecules) and show dendrimers to be spherical. The structural results give grounds to consider carbosilane dendrimers promising objects for forming crystals with subsequent structural analysis and determining their structure with high resolution, as well as for designing new materials to be used in various dendrimer-based technological applications.

  12. Study of the grazing-incidence X-ray scattering of strongly disturbed fractal surfaces

    NASA Astrophysics Data System (ADS)

    Roshchin, B. S.; Chukhovsky, F. N.; Pavlyuk, M. D.; Opolchentsev, A. M.; Asadchikov, V. E.

    2017-03-01

    The applicability of different approaches to the description of hard X-ray scattering from rough surfaces is generally limited by a maximum surface roughness height of no more than 1 nm. Meanwhile, this value is several times larger for the surfaces of different materials subjected to treatment, especially in the initial treatment stages. To control the roughness parameters in all stages of surface treatment, a new approach has been developed, which is based on a series expansion of wavefield over the plane eigenstate-function waves describing the small-angle scattering of incident X-rays in terms of plane q-waves propagating through the interface between two media with a random function of relief heights. To determine the amplitudes of reflected and transmitted plane q-waves, a system of two linked integral equations was derived. The solutions to these equations correspond (in zero order) to the well-known Fresnel expressions for a smooth plane interface. Based on these solutions, a statistical fractal model of an isotropic rough interface is built in terms of root-mean-square roughness σ, two-point correlation length l, and fractal surface index h. The model is used to interpret X-ray scattering data for polished surfaces of single-crystal cadmium telluride samples.

  13. Study of the grazing-incidence X-ray scattering of strongly disturbed fractal surfaces

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Roshchin, B. S., E-mail: ross@crys.ras.ru; Chukhovsky, F. N.; Pavlyuk, M. D.

    2017-03-15

    The applicability of different approaches to the description of hard X-ray scattering from rough surfaces is generally limited by a maximum surface roughness height of no more than 1 nm. Meanwhile, this value is several times larger for the surfaces of different materials subjected to treatment, especially in the initial treatment stages. To control the roughness parameters in all stages of surface treatment, a new approach has been developed, which is based on a series expansion of wavefield over the plane eigenstate-function waves describing the small-angle scattering of incident X-rays in terms of plane q-waves propagating through the interface betweenmore » two media with a random function of relief heights. To determine the amplitudes of reflected and transmitted plane q-waves, a system of two linked integral equations was derived. The solutions to these equations correspond (in zero order) to the well-known Fresnel expressions for a smooth plane interface. Based on these solutions, a statistical fractal model of an isotropic rough interface is built in terms of root-mean-square roughness σ, two-point correlation length l, and fractal surface index h. The model is used to interpret X-ray scattering data for polished surfaces of single-crystal cadmium telluride samples.« less

  14. The applications of small-angle X-ray scattering in studying nano-scaled polyoxometalate clusters in solutions

    NASA Astrophysics Data System (ADS)

    Li, Mu; Zhang, Mingxin; Wang, Weiyu; Cheng, Stephen Z. D.; Yin, Panchao

    2018-05-01

    Nano-scaled polyoxometalates (POMs) clusters with sizes ranging from 1 to 10 nm attract tremendous attention and have been extensively studied due to POMs' fascinating structural characteristics and prospects for wide-ranging applications. As a unique class of nanoparticles with well-defined structural topologies and monodispersed masses, the structures and properties of POMs in both bulk state and solutions have been explored with several well-developed protocols. Small-angle X-ray scattering (SAXS) technique, as a powerful tool for studying polymers and nanoparticles, has been recently extended to the investigating of solution behaviors of POMs. In this mini-review, the general principle and typical experimental procedures of SAXS are illustrated first. The applications of SAXS in characterizing POMs' morphology, counterion distribution around POMs, and short-range interactions among POMs in solutions are highlighted. [Figure not available: see fulltext.

  15. Densitometry and temperature measurement of combustion gas by X-ray Compton scattering

    PubMed Central

    Sakurai, Hiroshi; Kawahara, Nobuyuki; Itou, Masayoshi; Tomita, Eiji; Suzuki, Kosuke; Sakurai, Yoshiharu

    2016-01-01

    Measurement of combustion gas by high-energy X-ray Compton scattering is reported. The intensity of Compton-scattered X-rays has shown a position dependence across the flame of the combustion gas, allowing us to estimate the temperature distribution of the combustion flame. The energy spectra of Compton-scattered X-rays have revealed a significant difference across the combustion reaction zone, which enables us to detect the combustion reaction. These results demonstrate that high-energy X-ray Compton scattering can be employed as an in situ technique to probe inside a combustion reaction. PMID:26917151

  16. Densitometry and temperature measurement of combustion gas by X-ray Compton scattering.

    PubMed

    Sakurai, Hiroshi; Kawahara, Nobuyuki; Itou, Masayoshi; Tomita, Eiji; Suzuki, Kosuke; Sakurai, Yoshiharu

    2016-03-01

    Measurement of combustion gas by high-energy X-ray Compton scattering is reported. The intensity of Compton-scattered X-rays has shown a position dependence across the flame of the combustion gas, allowing us to estimate the temperature distribution of the combustion flame. The energy spectra of Compton-scattered X-rays have revealed a significant difference across the combustion reaction zone, which enables us to detect the combustion reaction. These results demonstrate that high-energy X-ray Compton scattering can be employed as an in situ technique to probe inside a combustion reaction.

  17. X-ray induced dimerization of cinnamic acid: Time-resolved inelastic X-ray scattering study

    PubMed Central

    Inkinen, Juho; Niskanen, Johannes; Talka, Tuomas; Sahle, Christoph J.; Müller, Harald; Khriachtchev, Leonid; Hashemi, Javad; Akbari, Ali; Hakala, Mikko; Huotari, Simo

    2015-01-01

    A classic example of solid-state topochemical reactions is the ultraviolet-light induced photodimerization of α-trans-cinnamic acid (CA). Here, we report the first observation of an X-ray-induced dimerization of CA and monitor it in situ using nonresonant inelastic X-ray scattering spectroscopy (NRIXS). The time-evolution of the carbon core-electron excitation spectra shows the effects of two X-ray induced reactions: dimerization on a short time-scale and disintegration on a long time-scale. We used spectrum simulations of CA and its dimerization product, α-truxillic acid (TA), to gain insight into the dimerization effects. From the time-resolved spectra, we extracted component spectra and time-dependent weights corresponding to CA and TA. The results suggest that the X-ray induced dimerization proceeds homogeneously in contrast to the dimerization induced by ultraviolet light. We also utilized the ability of NRIXS for direct tomography with chemical-bond contrast to image the spatial progress of the reactions in the sample crystal. Our work paves the way for other time-resolved studies on chemical reactions using inelastic X-ray scattering. PMID:26568420

  18. Intrinsic flexibility of West Nile virus protease in solution characterized using small-angle X-ray scattering.

    PubMed

    Garces, Andrea P; Watowich, Stanley J

    2013-10-01

    West Nile virus (WNV) is a mosquito-borne flavivirus with a rapidly expanding global distribution. Infection can cause severe neurological disease and fatality in humans. Efforts are ongoing to develop antiviral drugs that inhibit the WNV protease, a viral enzyme required for polyprotein processing. Unfortunately, little is known about the solution structure of recombinant WNV protease (NS2B-NS3pro) used for antiviral drug discovery and development, although X-ray crystal structures and nuclear magnetic resonance (NMR) studies have provided valuable insights into the interactions between NS2B-NS3pro and peptide-based inhibitors. We completed small-angle X-ray scattering and Fourier transform infrared spectroscopy experiments to determine the solution structure and dynamics of WNV NS2B-NS3pro in the absence of a bound substrate or inhibitor. Importantly, these solution studies suggested that all or most of the NS2B cofactor was highly flexible and formed an ensemble of structures, in contrast to the NS2B tertiary structures observed in crystallographic and NMR studies. The secondary structure of NS2B-NS3pro in solution had high β-content, similar to the secondary structure observed in crystallographic studies. This work provided evidence of the intrinsic flexibility and conformational heterogeneity of the NS2B chain of the WNV protease in the absence of substratelike ligands, which should be considered during antiviral drug discovery and development efforts.

  19. X-ray coherent scattering tomography of textured material (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Zhu, Zheyuan; Pang, Shuo

    2017-05-01

    Small-angle X-ray scattering (SAXS) measures the signature of angular-dependent coherently scattered X-rays, which contains richer information in material composition and structure compared to conventional absorption-based computed tomography. SAXS image reconstruction method of a 2 or 3 dimensional object based on computed tomography, termed as coherent scattering computed tomography (CSCT), enables the detection of spatially-resolved, material-specific isotropic scattering signature inside an extended object, and provides improved contrast for medical diagnosis, security screening, and material characterization applications. However, traditional CSCT methods assumes materials are fine powders or amorphous, and possess isotropic scattering profiles, which is not generally true for all materials. Anisotropic scatters cannot be captured using conventional CSCT method and result in reconstruction errors. To obtain correct information from the sample, we designed new imaging strategy which incorporates extra degree of detector motion into X-ray scattering tomography for the detection of anisotropic scattered photons from a series of two-dimensional intensity measurements. Using a table-top, narrow-band X-ray source and a panel detector, we demonstrate the anisotropic scattering profile captured from an extended object and the reconstruction of a three-dimensional object. For materials possessing a well-organized crystalline structure with certain symmetry, the scatter texture is more predictable. We will also discuss the compressive schemes and implementation of data acquisition to improve the collection efficiency and accelerate the imaging process.

  20. Resonant magnetic scattering of polarized soft x rays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sacchi, M.; Hague, C.F.; Gullikson, E.M.

    1997-04-01

    Magnetic effects on X-ray scattering (Bragg diffraction, specular reflectivity or diffuse scattering) are a well known phenomenon, and they also represent a powerful tool for investigating magnetic materials since it was shown that they are strongly enhanced when the photon energy is tuned across an absorption edge (resonant process). The resonant enhancement of the magnetic scattering has mainly been investigated at high photon energies, in order to match the Bragg law for the typical lattice spacings of crystals. In the soft X-ray range, even larger effects are expected, working for instance at the 2p edges of transition metals of themore » first row or at the 3d edges of rare earths (300-1500 eV), but the corresponding long wavelengths prevent the use of single crystals. Two approaches have been recently adopted in this energy range: (i) the study of the Bragg diffraction from artificial structures of appropriate 2d spacing; (ii) the analysis of the specular reflectivity, which contains analogous information but has no constraints related to the lattice spacing. Both approaches have their own specific advantages: for instance, working under Bragg conditions provides information about the (magnetic) periodicity in ordered structures, while resonant reflectivity can easily be related to electronic properties and absorption spectra. An important aspect common to all the resonant X-ray scattering techniques is the element selectivity inherent to the fact of working at a specific absorption edge: under these conditions, X-ray scattering becomes in fact a spectroscopy. Results are presented for films of iron and cobalt.« less

  1. Demonstration of imaging X-ray Thomson scattering on OMEGA EP.

    PubMed

    Belancourt, Patrick X; Theobald, Wolfgang; Keiter, Paul A; Collins, Tim J B; Bonino, Mark J; Kozlowski, Pawel M; Regan, Sean P; Drake, R Paul

    2016-11-01

    Foams are a common material for high-energy-density physics experiments because of low, tunable densities, and being machinable. Simulating these experiments can be difficult because the equation of state is largely unknown for shocked foams. The focus of this experiment was to develop an x-ray scattering platform for measuring the equation of state of shocked foams on OMEGA EP. The foam used in this experiment is resorcinol formaldehyde with an initial density of 0.34 g/cm 3 . One long-pulse (10 ns) beam drives a shock into the foam, while the remaining three UV beams with a 2 ns square pulse irradiate a nickel foil to create the x-ray backlighter. The primary diagnostic for this platform, the imaging x-ray Thomson spectrometer, spectrally resolves the scattered x-ray beam while imaging in one spatial dimension. Ray tracing analysis of the density profile gives a compression of 3 ± 1 with a shock speed of 39 ± 6 km/s. Analysis of the scattered x-ray spectra gives an upper bound temperature of 20 eV.

  2. PREFACE: Structure and dynamics determined by neutron and x-ray scattering Structure and dynamics determined by neutron and x-ray scattering

    NASA Astrophysics Data System (ADS)

    Müller-Buschbaum, Peter

    2011-06-01

    structure of pyroxene-type MnGeO3 G J Redhammer, A Senyshyn, G Tippelt and G Roth Nanostructured diblock copolymer films with embedded magnetic nanoparticles Xin Xia, Ezzeldin Metwalli, Matthias A Ruderer, Volker Körstgens, Peter Busch, Peter Böni and Peter Müller-Buschbaum Thermal expansion of a La-based bulk metallic glass: insight from in situ high-energy x-ray diffraction J Bednarcik, S Michalik, M Sikorski, C Curfs, X D Wang, J Z Jiang and H Franz The slow short-time motions of phospholipid molecules with a focus on the influence of multiple scattering and fitting artefacts Sebastian Busch and Tobias Unruh Quasi-elastic scattering under short-range order: the linear regime and beyond Michael Leitner and Gero Vogl Structural relaxation as seen by quasielastic neutron scattering on viscous Zr-Ti-Cu-Ni-Be droplets F Yang, T Kordel, D Holland-Moritz, T Unruh and A Meyer In situ observation of cluster formation during nanoparticle solution casting on a colloidal film S V Roth, G Herzog, V Körstgens, A Buffet, M Schwartzkopf, J Perlich, M M Abul Kashem, R Döhrmann, R Gehrke, A Rothkirch, K Stassig, W Wurth, G Benecke, C Li, P Fratzl, M Rawolle and P Müller-Buschbaum Inelastic neutron and x-ray scattering from incommensurate magnetic systems Peter Böni, Bertrand Roessli and Klaudia Hradil Development of magnetic moments in Fe1-xNix-alloys Benjamin Glaubitz, Stefan Buschhorn, Frank Brüssing, Radu Abrudan and Hartmut Zabel Modified mode-coupling theory for the collective dynamics of simple liquids B Schmid and W Schirmacher Inelastic neutron and low-frequency Raman scattering in niobium-phosphate glasses: the role of spatially fluctuating elastic and elasto-optic constants A Schulte, W Schirmacher, B Schmid and T Unruh The effect of heat treatment on the internal structure of nanostructured block copolymer films A Sepe, E T Hoppe, S Jaksch, D Magerl, Q Zhong, J Perlich, D Posselt, D-M Smilgies and C M Papadakis Hydrogen release from sodium alanate observed by time

  3. SoftWAXS: a computational tool for modeling wide-angle X-ray solution scattering from biomolecules.

    PubMed

    Bardhan, Jaydeep; Park, Sanghyun; Makowski, Lee

    2009-10-01

    This paper describes a computational approach to estimating wide-angle X-ray solution scattering (WAXS) from proteins, which has been implemented in a computer program called SoftWAXS. The accuracy and efficiency of SoftWAXS are analyzed for analytically solvable model problems as well as for proteins. Key features of the approach include a numerical procedure for performing the required spherical averaging and explicit representation of the solute-solvent boundary and the surface of the hydration layer. These features allow the Fourier transform of the excluded volume and hydration layer to be computed directly and with high accuracy. This approach will allow future investigation of different treatments of the electron density in the hydration shell. Numerical results illustrate the differences between this approach to modeling the excluded volume and a widely used model that treats the excluded-volume function as a sum of Gaussians representing the individual atomic excluded volumes. Comparison of the results obtained here with those from explicit-solvent molecular dynamics clarifies shortcomings inherent to the representation of solvent as a time-averaged electron-density profile. In addition, an assessment is made of how the calculated scattering patterns depend on input parameters such as the solute-atom radii, the width of the hydration shell and the hydration-layer contrast. These results suggest that obtaining predictive calculations of high-resolution WAXS patterns may require sophisticated treatments of solvent.

  4. X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser [X-ray Thomson scattering measurements from hohlraum targets on the OMEGA laser

    DOE PAGES

    Saunders, A. M.; Jenei, A.; Doppner, T.; ...

    2016-08-30

    X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH 2 targets on the OMEGA laser. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule, but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Here, knowledge gained in this experiment show a promising future for further XRTS measurements on indirectly driven OMEGA targets.

  5. X-ray Thomson scattering measurements from hohlraum-driven spheres on the OMEGA laser [X-ray Thomson scattering measurements from hohlraum targets on the OMEGA laser

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Saunders, A. M.; Jenei, A.; Doppner, T.

    X-ray Thomson scattering (XRTS) is a powerful diagnostic for probing warm and hot dense matter. We present the design and results of the first XRTS experiments with hohlraum-driven CH 2 targets on the OMEGA laser. X-rays seen directly from the XRTS x-ray source overshadow the elastic scattering signal from the target capsule, but can be controlled in future experiments. From the inelastic scattering signal, an average plasma temperature is inferred that is in reasonable agreement with the temperatures predicted by simulations. Here, knowledge gained in this experiment show a promising future for further XRTS measurements on indirectly driven OMEGA targets.

  6. Three-dimensional reciprocal space x-ray coherent scattering tomography of two-dimensional object.

    PubMed

    Zhu, Zheyuan; Pang, Shuo

    2018-04-01

    X-ray coherent scattering tomography is a powerful tool in discriminating biological tissues and bio-compatible materials. Conventional x-ray scattering tomography framework can only resolve isotropic scattering profile under the assumption that the material is amorphous or in powder form, which is not true especially for biological samples with orientation-dependent structure. Previous tomography schemes based on x-ray coherent scattering failed to preserve the scattering pattern from samples with preferred orientations, or required elaborated data acquisition scheme, which could limit its application in practical settings. Here, we demonstrate a simple imaging modality to preserve the anisotropic scattering signal in three-dimensional reciprocal (momentum transfer) space of a two-dimensional sample layer. By incorporating detector movement along the direction of x-ray beam, combined with a tomographic data acquisition scheme, we match the five dimensions of the measurements with the five dimensions (three in momentum transfer domain, and two in spatial domain) of the object. We employed a collimated pencil beam of a table-top copper-anode x-ray tube, along with a panel detector to investigate the feasibility of our method. We have demonstrated x-ray coherent scattering tomographic imaging at a spatial resolution ~2 mm and momentum transfer resolution 0.01 Å -1 for the rotation-invariant scattering direction. For any arbitrary, non-rotation-invariant direction, the same spatial and momentum transfer resolution can be achieved based on the spatial information from the rotation-invariant direction. The reconstructed scattering profile of each pixel from the experiment is consistent with the x-ray diffraction profile of each material. The three-dimensional scattering pattern recovered from the measurement reveals the partially ordered molecular structure of Teflon wrap in our sample. We extend the applicability of conventional x-ray coherent scattering tomography to

  7. Assessment of surface roughness by use of soft x-ray scattering

    NASA Astrophysics Data System (ADS)

    Meng, Yan-li; Wang, Yong-gang; Chen, Shu-yan; Chen, Bo

    2009-08-01

    A soft x-ray reflectometer with laser produced plasma source has been designed, which can work from wavelength 8nm to 30 nm and has high performance. Using the soft x-ray reflectometer above, the scattering light distribution of silicon and zerodur mirrors which have super-smooth surfaces could be measured at different incidence angle and different wavelength. The measurement when the incidence angle is 2 degree and the wavelength is 11nm has been given in this paper. A surface scattering theory of soft x-ray grazing incidence optics based on linear system theory and an inverse scattering mathematical model is introduced. The vector scattering theory of soft x-ray scattering also is stated in detail. The scattering data are analyzed by both the methods above respectively to give information about the surface profiles. On the other hand, both the two samples are measured by WYKO surface profiler, and the surface roughness of the silicon and zerodur mirror is 1.3 nm and 1.5nm respectively. The calculated results are in quantitative agreement with those measured by WYKO surface profiler, which indicates that soft x-ray scattering is a very useful tool for the evaluation of highly polished surfaces. But there still some difference among the results of different theory and WYKO, and the possible reasons of such difference have been discussed in detail.

  8. Dynamic Conformations of Nucleosome Arrays in Solution from Small-Angle X-ray Scattering

    NASA Astrophysics Data System (ADS)

    Howell, Steven C.

    Chromatin conformation and dynamics remains unsolved despite the critical role of the chromatin in fundamental genetic functions such as transcription, replication, and repair. At the molecular level, chromatin can be viewed as a linear array of nucleosomes, each consisting of 147 base pairs (bp) of double-stranded DNA (dsDNA) wrapped around a protein core and connected by 10 to 90 bp of linker dsDNA. Using small-angle X-ray scattering (SAXS), we investigated how the conformations of model nucleosome arrays in solution are modulated by ionic condition as well as the effect of linker histone proteins. To facilitate ensemble modeling of these SAXS measurements, we developed a simulation method that treats coarse-grained DNA as a Markov chain, then explores possible DNA conformations using Metropolis Monte Carlo (MC) sampling. This algorithm extends the functionality of SASSIE, a program used to model intrinsically disordered biological molecules, adding to the previous methods for simulating protein, carbohydrates, and single-stranded DNA. Our SAXS measurements of various nucleosome arrays together with the MC generated models provide valuable solution structure information identifying specific differences from the structure of crystallized arrays.

  9. Soft X-ray radiation damage in EM-CCDs used for Resonant Inelastic X-ray Scattering

    NASA Astrophysics Data System (ADS)

    Gopinath, D.; Soman, M.; Holland, A.; Keelan, J.; Hall, D.; Holland, K.; Colebrook, D.

    2018-02-01

    Advancement in synchrotron and free electron laser facilities means that X-ray beams with higher intensity than ever before are being created. The high brilliance of the X-ray beam, as well as the ability to use a range of X-ray energies, means that they can be used in a wide range of applications. One such application is Resonant Inelastic X-ray Scattering (RIXS). RIXS uses the intense and tuneable X-ray beams in order to investigate the electronic structure of materials. The photons are focused onto a sample material and the scattered X-ray beam is diffracted off a high resolution grating to disperse the X-ray energies onto a position sensitive detector. Whilst several factors affect the total system energy resolution, the performance of RIXS experiments can be limited by the spatial resolution of the detector used. Electron-Multiplying CCDs (EM-CCDs) at high gain in combination with centroiding of the photon charge cloud across several detector pixels can lead to sub-pixel spatial resolution of 2-3 μm. X-ray radiation can cause damage to CCDs through ionisation damage resulting in increases in dark current and/or a shift in flat band voltage. Understanding the effect of radiation damage on EM-CCDs is important in order to predict lifetime as well as the change in performance over time. Two CCD-97s were taken to PTB at BESSY II and irradiated with large doses of soft X-rays in order to probe the front and back surfaces of the device. The dark current was shown to decay over time with two different exponential components to it. This paper will discuss the use of EM-CCDs for readout of RIXS spectrometers, and limitations on spatial resolution, together with any limitations on instrument use which may arise from X-ray-induced radiation damage.

  10. Small angle x-ray scattering with edge-illumination

    NASA Astrophysics Data System (ADS)

    Modregger, Peter; Cremona, Tiziana P.; Benarafa, Charaf; Schittny, Johannes C.; Olivo, Alessandro; Endrizzi, Marco

    2016-08-01

    Sensitivity to sub-pixel sample features has been demonstrated as a valuable capability of phase contrast x-ray imaging. Here, we report on a method to obtain angular-resolved small angle x-ray scattering distributions with edge-illumination- based imaging utilizing incoherent illumination from an x-ray tube. Our approach provides both the three established image modalities (absorption, differential phase and scatter strength), plus a number of additional contrasts related to unresolved sample features. The complementarity of these contrasts is experimentally validated by using different materials in powder form. As a significant application example we show that the extended complementary contrasts could allow the diagnosis of pulmonary emphysema in a murine model. In support of this, we demonstrate that the properties of the retrieved scattering distributions are consistent with the expectation of increased feature sizes related to pulmonary emphysema. Combined with the simplicity of implementation of edge-illumination, these findings suggest a high potential for exploiting extended sub-pixel contrasts in the diagnosis of lung diseases and beyond.

  11. X-Ray Absorption Measured in the Resonant Auger Scattering Mode

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hikosaka, Y.; Shigemasa, E.; Kaneyasu, T.

    2008-08-15

    We report both experimental and theoretical studies on x-ray absorption measured in the resonant Auger scattering mode of gas phase carbon monoxide near the O1s{yields}2{pi} region. Both experiment and theory display a crucial difference between the x-ray absorption profiles obtained in the conventional and resonant scattering modes. Lifetime vibrational interference is the main source of the difference. It is demonstrated that such interference, which arises from a coherent excitation to overlapping intermediate levels, ruins the idea for obtaining x-ray absorption spectra in a lifetime broadening free regime.

  12. Bringing diffuse X-ray scattering into focus

    DOE PAGES

    Wall, Michael E.; Wolff, Alexander M.; Fraser, James S.

    2018-02-16

    X-ray crystallography is experiencing a renaissance as a method for probing the protein conformational ensemble. The inherent limitations of Bragg analysis, however, which only reveals the mean structure, have given way to a surge in interest in diffuse scattering, which is caused by structure variations. Diffuse scattering is present in all macromolecular crystallography experiments. Recent studies are shedding light on the origins of diffuse scattering in protein crystallography, and provide clues for leveraging diffuse scattering to model protein motions with atomic detail.

  13. Bringing diffuse X-ray scattering into focus

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wall, Michael E.; Wolff, Alexander M.; Fraser, James S.

    X-ray crystallography is experiencing a renaissance as a method for probing the protein conformational ensemble. The inherent limitations of Bragg analysis, however, which only reveals the mean structure, have given way to a surge in interest in diffuse scattering, which is caused by structure variations. Diffuse scattering is present in all macromolecular crystallography experiments. Recent studies are shedding light on the origins of diffuse scattering in protein crystallography, and provide clues for leveraging diffuse scattering to model protein motions with atomic detail.

  14. Preliminary small-angle X-ray scattering and X-ray diffraction studies of the BTB domain of lola protein from Drosophila melanogaster

    NASA Astrophysics Data System (ADS)

    Boyko, K. M.; Nikolaeva, A. Yu.; Kachalova, G. S.; Bonchuk, A. N.; Dorovatovskii, P. V.; Popov, V. O.

    2017-11-01

    The Drosophila genome has several dozens of transcription factors (TTK group) containing BTB domains assembled into octamers. The LOLA protein belongs to this family. The purification, crystallization, and preliminary X-ray diffraction and small-angle X-ray scattering (SAXS) studies of the BTB domain of this protein are reported. The crystallization conditions were found by the vapor-diffusion technique. A very low diffraction resolution (8.7 Å resolution) of the crystals was insufficient for the determination of the threedimensional structure of the BTB domain. The SAXS study demonstrated that the BTB domain of the LOLA protein exists as an octamer in solution.

  15. X-ray Raman spectroscopy of lithium-ion battery electrolyte solutions in a flow cell.

    PubMed

    Ketenoglu, Didem; Spiekermann, Georg; Harder, Manuel; Oz, Erdinc; Koz, Cevriye; Yagci, Mehmet C; Yilmaz, Eda; Yin, Zhong; Sahle, Christoph J; Detlefs, Blanka; Yavaş, Hasan

    2018-03-01

    The effects of varying LiPF 6 salt concentration and the presence of lithium bis(oxalate)borate additive on the electronic structure of commonly used lithium-ion battery electrolyte solvents (ethylene carbonate-dimethyl carbonate and propylene carbonate) have been investigated. X-ray Raman scattering spectroscopy (a non-resonant inelastic X-ray scattering method) was utilized together with a closed-circle flow cell. Carbon and oxygen K-edges provide characteristic information on the electronic structure of the electrolyte solutions, which are sensitive to local chemistry. Higher Li + ion concentration in the solvent manifests itself as a blue-shift of both the π* feature in the carbon edge and the carbonyl π* feature in the oxygen edge. While these oxygen K-edge results agree with previous soft X-ray absorption studies on LiBF 4 salt concentration in propylene carbonate, carbon K-edge spectra reveal a shift in energy, which can be explained with differing ionic conductivities of the electrolyte solutions.

  16. SU-E-I-44: Some Preliminary Analysis of Angular Distribution of X-Ray Scattered On Soft Tissues

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ganezer, K; Krmar, M; Cvejic, Z

    2015-06-15

    Purpose: The angular distribution of x-radiation scattered at small angles (up to 16 degrees) from several different animal soft tissue (skin, fat, muscle, retina, etc) were measured using standard equipment devoted to study of crystal structure which provides excellent geometry conditions of measurements. showed measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Methods: An x-ray scattering profilemore » usually consists of sharp diffraction peak; however some properties of the spatial profiles of scattered radiation as intensity, the peak position, height, area, FWHM, the ratio of peak heights, etc. Results: The data contained measurable differences for different tissues. In the simplest possible case when measured samples do not differ in structure (different concentration solutions) it can be seen that intensity of scattered radiation is decreasing function of the concentration and the peak of the maximum of scattering distribution depends on the concentration as well. Measurements of different samples in the very preliminary phase showed that simple biological material used in study showed slightly different scattering pattern, especially at higher angles (around 10degrees). Intensity of radiation scattered from same tissue type is very dependent on water content and several more parameters. Conclusion: This preliminary study using animal soft tissues on the angular distributions of scattered x-rays suggests that angular distributions of X-rays scattered off of soft tissues might be useful in distinguishing healthy tissue from malignant soft tissue.« less

  17. Spectrally resolving and scattering-compensated x-ray luminescence/fluorescence computed tomography

    PubMed Central

    Cong, Wenxiang; Shen, Haiou; Wang, Ge

    2011-01-01

    The nanophosphors, or other similar materials, emit near-infrared (NIR) light upon x-ray excitation. They were designed as optical probes for in vivo visualization and analysis of molecular and cellular targets, pathways, and responses. Based on the previous work on x-ray fluorescence computed tomography (XFCT) and x-ray luminescence computed tomography (XLCT), here we propose a spectrally-resolving and scattering-compensated x-ray luminescence/fluorescence computed tomography (SXLCT or SXFCT) approach to quantify a spatial distribution of nanophosphors (other similar materials or chemical elements) within a biological object. In this paper, the x-ray scattering is taken into account in the reconstruction algorithm. The NIR scattering is described in the diffusion approximation model. Then, x-ray excitations are applied with different spectra, and NIR signals are measured in a spectrally resolving fashion. Finally, a linear relationship is established between the nanophosphor distribution and measured NIR data using the finite element method and inverted using the compressive sensing technique. The numerical simulation results demonstrate the feasibility and merits of the proposed approach. PMID:21721815

  18. First refraction contrast imaging via Laser-Compton Scattering X-ray at KEK

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sakaue, Kazuyuki; Aoki, Tatsuro; Washio, Masakazu

    2012-07-31

    Laser-Compton Scattering (LCS) is one of the most feasible techniques for high quality, high brightness, and compact X-ray source. High energy electron beam produced by accelerators scatters off the laser photon at a small spot. As a laser target, we have been developing a pulsedlaser storage cavity for increasing an X-ray flux. The X-ray flux was still inadequate that was 2.1 Multiplication-Sign 10{sup 5}/sec, however, we performed first refraction contrast imaging in order to evaluate the quality of LCS X-ray. Edge enhanced contrast imaging was achieved by changing the distance from sample to detector. The edge enhancement indicates that themore » LCS X-ray has small source size, i.e. high brightness. We believe that the result has demonstrated good feasibility of linac-based high brightness X-ray sources via laser-electron Compton scatterings.« less

  19. Toroidal silicon polarization analyzer for resonant inelastic x-ray scattering

    DOE PAGES

    Gao, Xuan; Casa, Diego; Kim, Jungho; ...

    2016-08-15

    Resonant Inelastic X-ray Scattering (RIXS) is a powerful probe for studying electronic excitations in materials. Standard high energy RIXS measurements do not measure the polarization of the scattered x-rays, which is unfortunate since it carries information about the nature and symmetry of the excitations involved in the scattering process. Moreover we report the fabrication of thin Si-based polarization analyzers with a double-concave toroidal surface, useful for L-edge RIXS studies in heavier atoms such as the 5-d transition metals.

  20. Calculation of x-ray scattering patterns from nanocrystals at high x-ray intensity

    PubMed Central

    Abdullah, Malik Muhammad; Jurek, Zoltan; Son, Sang-Kil; Santra, Robin

    2016-01-01

    We present a generalized method to describe the x-ray scattering intensity of the Bragg spots in a diffraction pattern from nanocrystals exposed to intense x-ray pulses. Our method involves the subdivision of a crystal into smaller units. In order to calculate the dynamics within every unit, we employ a Monte-Carlo-molecular dynamics-ab-initio hybrid framework using real space periodic boundary conditions. By combining all the units, we simulate the diffraction pattern of a crystal larger than the transverse x-ray beam profile, a situation commonly encountered in femtosecond nanocrystallography experiments with focused x-ray free-electron laser radiation. Radiation damage is not spatially uniform and depends on the fluence associated with each specific region inside the crystal. To investigate the effects of uniform and non-uniform fluence distribution, we have used two different spatial beam profiles, Gaussian and flattop. PMID:27478859

  1. Ultrafast Independent N-H and N-C Bond Deformation Investigated with Resonant Inelastic X-Ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Eckert, Sebastian; Norell, Jesper; Miedema, Piter S.

    Here, the femtosecond excited-state dynamics following resonant photoexcitation enable the selective deformation of N-H and N-C chemical bonds in 2-thiopyridone in aqueous solution with optical or X-ray pulses. In combination with multiconfigurational quantum-chemical calculations, the orbital-specific electronic structure and its ultrafast dynamics accessed with resonant inelastic X-ray scattering at the N 1s level using synchrotron radiation and the soft X-ray free-electron laser LCLS provide direct evidence for this controlled photoinduced molecular deformation and its ultrashort timescale.

  2. Ultrafast Independent N-H and N-C Bond Deformation Investigated with Resonant Inelastic X-Ray Scattering

    DOE PAGES

    Eckert, Sebastian; Norell, Jesper; Miedema, Piter S.; ...

    2017-04-04

    Here, the femtosecond excited-state dynamics following resonant photoexcitation enable the selective deformation of N-H and N-C chemical bonds in 2-thiopyridone in aqueous solution with optical or X-ray pulses. In combination with multiconfigurational quantum-chemical calculations, the orbital-specific electronic structure and its ultrafast dynamics accessed with resonant inelastic X-ray scattering at the N 1s level using synchrotron radiation and the soft X-ray free-electron laser LCLS provide direct evidence for this controlled photoinduced molecular deformation and its ultrashort timescale.

  3. Resonant Soft X-ray Scattering as a Powerful Probe of Buried Polymer Interfaces

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Jiang, Zhang; Tirrell, Matthew

    Elucidation of polymer interfacial structures provides insights into interfacial molecular mechanisms for coating protection, adhesion, lubrication, friction, wettability, biocompatibility, and even charge transport properties. Resonant Soft X-ray Scattering (RSoXS) offers a unique element, site and valence specific probe to study spatial modulations of molecular orbital degrees of freedom on the nanoscopic length scale. This unique sensitivity is achieved by merging small angle x-ray scattering and x-ray absorption spectroscopy into a single experiment, where the scattering provides information about spatial modulations and the spectroscopy provides sensitivity to the molecular anisotropy. Here we applied RSoXS to polystyrene (PS) films at solid-solid interfaces and poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) brushes at solid-liquid interfaces. It is found that the interfacial width of PS thin film is about one order of magnitude large than those observed by traditional scattering techniques. In addition, although the ion-induced changes of PMPC thickness are not apparent in aqueous solutions, their chain conformations like polyzwitterion distribution and correlation varied, dependent on salt types, ionic strengths and ion valences. Consequently, it is evident that RSoXS is a powerful probe of buried polymer interlaces with both spatial and chemical sensitivities. This work was supported by the U.S. Department of Energy, Office of Science, Program in Basic Energy Sciences, Division of Materials Science and Engineering.

  4. X-ray resonant magnetic scattering ellipsometer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

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

    1996-09-01

    It is very difficult to characterize the polarization of a synchrotron radiation source in the soft and/or intermediate x-ray energy region particularly from 1 to 2 keV. Conventional multilayer mirror or single-crystal polarimeters do not work over this energy region because their throughput (the reflectivities combined with the phase shift) becomes insignificant. In this paper, we present a new ellipsometer scheme that is able to fully characterize the polarization of synchrotron radiation sources in this energy region. It is based on the dichroic x-ray resonant ferromagnetic scattering that yields information on both the polarization of the x-ray and the materialmore » (element specific) dielectric-constant tensor [C.-C. Kao {ital et} {ital al}., Phys. Rev. B {bold 50}, 9599 (1994)] due to the interband ferromagnetic Kerr effect [B.R. Cooper, Phys. Rev. A {bold 139}, 1504 (1965)]. {copyright} {ital 1996 American Institute of Physics.}« less

  5. X-ray Diffuse Scattering from Ultrafast Laser Excited Solids

    NASA Astrophysics Data System (ADS)

    Trigo, Mariano; Sheu, Yu-Miin; Chen, Jian; Reis, David; Fahy, Stephen; Murray, Eamonn; Graber, Timothy; Henning, Robert

    2009-03-01

    Intense, ultrashort laser pulses can be used to excite and detect coherent phonons in solids. However, optical experiments can only probe a reduced fraction of the Brillouin zone and hence most of the decay channels of such coherent phonons become invisible. In contrast, time-resolved x-ray diffuse scattering (TRXDS) has the potential to be the ultimate tool to study these phonon decay processes throughout the Brillouin-zone of the crystal. In our work, performed at the BioCARS beamline at the Advanced Photon Source, we use synchrotron time-resolved diffuse x-ray scattering to study Si and Bi under intense laser excitation with 100 ps resolution. We show that reasonable signal levels can be achieved with incident flux of 10^12 photons comparable to the flux that will be available at future 4th generation sources such as the LCLS in a single pulse. These sources will also provide three orders of magnitude shorter pulses; thus, this experiment serves as a test of the feasibility of time-resolved X-ray diffuse scattering as a tool for studying nonequilibrium phonon dynamics in solids.

  6. Advanced ensemble modelling of flexible macromolecules using X-ray solution scattering.

    PubMed

    Tria, Giancarlo; Mertens, Haydyn D T; Kachala, Michael; Svergun, Dmitri I

    2015-03-01

    Dynamic ensembles of macromolecules mediate essential processes in biology. Understanding the mechanisms driving the function and molecular interactions of 'unstructured' and flexible molecules requires alternative approaches to those traditionally employed in structural biology. Small-angle X-ray scattering (SAXS) is an established method for structural characterization of biological macromolecules in solution, and is directly applicable to the study of flexible systems such as intrinsically disordered proteins and multi-domain proteins with unstructured regions. The Ensemble Optimization Method (EOM) [Bernadó et al. (2007 ▶). J. Am. Chem. Soc. 129, 5656-5664] was the first approach introducing the concept of ensemble fitting of the SAXS data from flexible systems. In this approach, a large pool of macromolecules covering the available conformational space is generated and a sub-ensemble of conformers coexisting in solution is selected guided by the fit to the experimental SAXS data. This paper presents a series of new developments and advancements to the method, including significantly enhanced functionality and also quantitative metrics for the characterization of the results. Building on the original concept of ensemble optimization, the algorithms for pool generation have been redesigned to allow for the construction of partially or completely symmetric oligomeric models, and the selection procedure was improved to refine the size of the ensemble. Quantitative measures of the flexibility of the system studied, based on the characteristic integral parameters of the selected ensemble, are introduced. These improvements are implemented in the new EOM version 2.0, and the capabilities as well as inherent limitations of the ensemble approach in SAXS, and of EOM 2.0 in particular, are discussed.

  7. Large-angle x-ray scatter in Talbot-Lau interferometry for breast imaging

    PubMed Central

    Vedantham, Srinivasan; Shi, Linxi; Karellas, Andrew

    2014-01-01

    Monte Carlo simulations were used to investigate large-angle x-ray scatter at design energy of 25 keV during small field of view (9.6 cm × 5 cm) differential phase contrast imaging of the breast using Talbot-Lau interferometry. Homogenous, adipose and fibroglandular breasts of uniform thickness ranging from 2 to 8 cm encompassing the field of view were modeled. Theoretically determined transmission efficiencies of the gratings were used to validate the Monte Carlo simulations, followed by simulations to determine the x-ray scatter reaching the detector. The recorded x-ray scatter was classified into x-ray photons that underwent at least one Compton interaction (incoherent scatter) and Rayleigh interaction alone (coherent scatter) for further analysis. Monte Carlo based estimates of transmission efficiencies showed good correspondence (r2 > 0.99) with theoretical estimates. Scatter-to-primary ratio increased with increasing breast thickness, ranging from 0.11 to 0.22 for 2 to 8 cm thick adipose breasts and from 0.12 to 0.28 for 2 to 8 cm thick fibroglandular breasts. The analyzer grating reduced incoherent scatter by ~18% for 2 cm thick adipose breast and by ~35% for 8 cm thick fibroglandular breast. Coherent scatter was the dominant contributor to the total scatter. Coherent-to-incoherent scatter ratio ranged from 2.2 to 3.1 for 2 to 8 cm thick adipose breasts and from 2.7 to 3.4 for 2 to 8 cm thick fibroglandular breasts. PMID:25295630

  8. Small-angle x-ray scattering investigations of extrudates

    NASA Astrophysics Data System (ADS)

    Pikus, Stanislaw; Jamroz, Jerzy

    1997-02-01

    The small-angle X-ray scattering investigations of the extrudes are presented. The investigations of the different samples of starch by means of the SAXS indicate the new possibilities for using this method for extrudates examination. Results obtained by SAXS method of close dependance between intensity SAXS scattering and characteristic parameters of the extrudates were shown.

  9. Inelastic X-ray Scattering from Shocked Liquid Deuterium

    DOE PAGES

    Regan, S. P.; Falk, K.; Gregori, G.; ...

    2012-12-28

    The Fermi-degenerate plasma conditions created in liquid deuterium by a laser-ablation—driven shock wave were probed with noncollective, spectrally resolved, inelastic x-ray Thomson scattering employing Cl Ly α line emission at 2.96 keV. Thus, these first x-ray Thomson scattering measurements of the microscopic properties of shocked deuterium show an inferred spatially averaged electron temperature of 8±5 eV, an electron density of 2.2(±0.5)×10 23 cm -3, and an ionization of 0.8 (-0.25, +0.15). Our two-dimensional hydrodynamic simulations using equation-of-state models suited for the extreme parameters occurring in inertial confinement fusion research and planetary interiors are consistent with the experimental results.

  10. Ab initio calculation of the ion feature in x-ray Thomson scattering.

    PubMed

    Plagemann, Kai-Uwe; Rüter, Hannes R; Bornath, Thomas; Shihab, Mohammed; Desjarlais, Michael P; Fortmann, Carsten; Glenzer, Siegfried H; Redmer, Ronald

    2015-07-01

    The spectrum of x-ray Thomson scattering is proportional to the dynamic structure factor. An important contribution is the ion feature which describes elastic scattering of x rays off electrons. We apply an ab initio method for the calculation of the form factor of bound electrons, the slope of the screening cloud of free electrons, and the ion-ion structure factor in warm dense beryllium. With the presented method we can calculate the ion feature from first principles. These results will facilitate a better understanding of x-ray scattering in warm dense matter and an accurate measurement of ion temperatures which would allow determining nonequilibrium conditions, e.g., along shock propagation.

  11. Demonstration of x-ray Thomson scattering using picosecond K-α x-ray sources in the characterization of dense heated matter

    DOE PAGES

    Kritcher, A. L.; Neumayer, P.; Lee, H. J.; ...

    2008-10-31

    Here, we present K-α x-ray Thomson scattering from shock compressed matter for use as a diagnostic in determining the temperature, density, and ionization state with picosecond resolution. The development of this source as a diagnostic as well as stringent requirements for successful K-α x-ray Thomson scattering are addressed. Here, the first elastic and inelastic scattering measurements on a medium size laser facility have been observed. We present scattering data from solid density carbon plasmas with >1X 10 5 photons in the elastic peak that validate the capability of single shot characterization of warm dense matter and the ability to usemore » this scattering source at future free electron lasers and for fusion experiments at the National Ignition Facility (NIF), LLNL.« less

  12. Predicting X-ray diffuse scattering from translation–libration–screw structural ensembles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Van Benschoten, Andrew H.; Afonine, Pavel V.; Terwilliger, Thomas C.

    2015-07-28

    A method of simulating X-ray diffuse scattering from multi-model PDB files is presented. Despite similar agreement with Bragg data, different translation–libration–screw refinement strategies produce unique diffuse intensity patterns. Identifying the intramolecular motions of proteins and nucleic acids is a major challenge in macromolecular X-ray crystallography. Because Bragg diffraction describes the average positional distribution of crystalline atoms with imperfect precision, the resulting electron density can be compatible with multiple models of motion. Diffuse X-ray scattering can reduce this degeneracy by reporting on correlated atomic displacements. Although recent technological advances are increasing the potential to accurately measure diffuse scattering, computational modeling andmore » validation tools are still needed to quantify the agreement between experimental data and different parameterizations of crystalline disorder. A new tool, phenix.diffuse, addresses this need by employing Guinier’s equation to calculate diffuse scattering from Protein Data Bank (PDB)-formatted structural ensembles. As an example case, phenix.diffuse is applied to translation–libration–screw (TLS) refinement, which models rigid-body displacement for segments of the macromolecule. To enable the calculation of diffuse scattering from TLS-refined structures, phenix.tls-as-xyz builds multi-model PDB files that sample the underlying T, L and S tensors. In the glycerophosphodiesterase GpdQ, alternative TLS-group partitioning and different motional correlations between groups yield markedly dissimilar diffuse scattering maps with distinct implications for molecular mechanism and allostery. These methods demonstrate how, in principle, X-ray diffuse scattering could extend macromolecular structural refinement, validation and analysis.« less

  13. Solution x-ray scattering and structure formation in protein dynamics

    NASA Astrophysics Data System (ADS)

    Nasedkin, Alexandr; Davidsson, Jan; Niemi, Antti J.; Peng, Xubiao

    2017-12-01

    We propose a computationally effective approach that builds on Landau mean-field theory in combination with modern nonequilibrium statistical mechanics to model and interpret protein dynamics and structure formation in small- to wide-angle x-ray scattering (S/WAXS) experiments. We develop the methodology by analyzing experimental data in the case of Engrailed homeodomain protein as an example. We demonstrate how to interpret S/WAXS data qualitatively with a good precision and over an extended temperature range. We explain experimental observations in terms of protein phase structure, and we make predictions for future experiments and for how to analyze data at different ambient temperature values. We conclude that the approach we propose has the potential to become a highly accurate, computationally effective, and predictive tool for analyzing S/WAXS data. For this, we compare our results with those obtained previously in an all-atom molecular dynamics simulation.

  14. Determination of the conformational ensemble of the TAR RNA by X-ray scattering interferometry

    PubMed Central

    Walker, Peter

    2017-01-01

    Abstract The conformational ensembles of structured RNA's are crucial for biological function, but they remain difficult to elucidate experimentally. We demonstrate with HIV-1 TAR RNA that X-ray scattering interferometry (XSI) can be used to determine RNA conformational ensembles. X-ray scattering interferometry (XSI) is based on site-specifically labeling RNA with pairs of heavy atom probes, and precisely measuring the distribution of inter-probe distances that arise from a heterogeneous mixture of RNA solution structures. We show that the XSI-based model of the TAR RNA ensemble closely resembles an independent model derived from NMR-RDC data. Further, we show how the TAR RNA ensemble changes shape at different salt concentrations. Finally, we demonstrate that a single hybrid model of the TAR RNA ensemble simultaneously fits both the XSI and NMR-RDC data set and show that XSI can be combined with NMR-RDC to further improve the quality of the determined ensemble. The results suggest that XSI-RNA will be a powerful approach for characterizing the solution conformational ensembles of RNAs and RNA-protein complexes under diverse solution conditions. PMID:28108663

  15. Determination of the conformational ensemble of the TAR RNA by X-ray scattering interferometry.

    PubMed

    Shi, Xuesong; Walker, Peter; Harbury, Pehr B; Herschlag, Daniel

    2017-05-05

    The conformational ensembles of structured RNA's are crucial for biological function, but they remain difficult to elucidate experimentally. We demonstrate with HIV-1 TAR RNA that X-ray scattering interferometry (XSI) can be used to determine RNA conformational ensembles. X-ray scattering interferometry (XSI) is based on site-specifically labeling RNA with pairs of heavy atom probes, and precisely measuring the distribution of inter-probe distances that arise from a heterogeneous mixture of RNA solution structures. We show that the XSI-based model of the TAR RNA ensemble closely resembles an independent model derived from NMR-RDC data. Further, we show how the TAR RNA ensemble changes shape at different salt concentrations. Finally, we demonstrate that a single hybrid model of the TAR RNA ensemble simultaneously fits both the XSI and NMR-RDC data set and show that XSI can be combined with NMR-RDC to further improve the quality of the determined ensemble. The results suggest that XSI-RNA will be a powerful approach for characterizing the solution conformational ensembles of RNAs and RNA-protein complexes under diverse solution conditions. © The Author(s) 2017. Published by Oxford University Press on behalf of Nucleic Acids Research.

  16. 2011 U.S. National School on Neutron and X-ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lang, Jonathan; te Vethuis, Suzanne; Ekkebus, Allen E

    The 13th annual U.S. National School on Neutron and X-ray Scattering was held June 11 to 25, 2011, at both Oak Ridge and Argonne National Laboratories. This school brought together 65 early career graduate students from 56 different universities in the US and provided them with a broad introduction to the techniques available at the major large-scale neutron and synchrotron x-ray facilities. This school is focused primarily on techniques relevant to the physical sciences, but also touches on cross-disciplinary bio-related scattering measurements. During the school, students received lectures by over 30 researchers from academia, industry, and national laboratories and participatedmore » in a number of short demonstration experiments at Argonne's Advanced Photon Source (APS) and Oak Ridge's Spallation neutron Source (SNS) and High Flux Isotope Reactor (HFIR) facilities to get hands-on experience in using neutron and synchrotron sources. The first week of this year's school was held at Oak Ridge National Lab, where Lab director Thom Mason welcomed the students and provided a shitorical perspective of the neutron and x-ray facilities both at Oak Ridge and Argonne. The first few days of the school were dedicated to lectures laying out the basics of scattering theory and the differences and complementarity between the neutron and x-ray probes given by Sunil Sinha. Jack Carpenter provided an introduction into how neutrons are generated and detected. After this basic introduction, the students received lectures each morning on specific techniques and conducted demonstration experiments each afternoon on one of 15 different instruments at either the SNS or HFIR. Some of the topics covered during this week of the school included inelastic neutron scattering by Bruce Gaulin, x-ray and neutron reflectivity by Chuck Majkrazak, small-angle scattering by Volker Urban, powder diffraction by Ashfia Huq and diffuse scattering by Gene Ice.« less

  17. Small-angle X-ray scattering (SAXS) studies of the structure of mesoporous silicas

    NASA Astrophysics Data System (ADS)

    Zienkiewicz-Strzałka, M.; Skibińska, M.; Pikus, S.

    2017-11-01

    Mesoporous ordered silica nanostructures show strong interaction with X-ray radiation in the range of small-angles. Small-angle X-ray scattering (SAXS) measurements based on the elastically scattered X-rays are important in analysis of condensed matter. In the case of mesoporous silica materials SAXS technique provides information on the distribution of electron density in the mesoporous material, in particular describing their structure and size of the unit cell as well as type of ordered structure and finally their parameters. The characterization of nanopowder materials, nanocomposites and porous materials by Small-Angle X-ray Scattering seems to be valuable and useful. In presented work, the SAXS investigation of structures from the group of mesoporous ordered silicates was performed. This work has an objective to prepare functional materials modified by noble metal ions and nanoparticles and using the small-angle X-ray scattering to illustrate their properties. We report the new procedure for describing mesoporous materials belonging to SBA-15 and MCM-41 family modified by platinum, palladium and silver nanoparticles, based on detailed analysis of characteristic peaks in the small-angle range of X-ray scattering. This procedure allows to obtained the most useful parameters for mesoporous materials characterization and their successfully compare with experimental measurements reducing the time and material consumption with good precision for particles and pores with a size below 10 nm.

  18. The study of X-ray scattering to determine surface topography of smooth surfaces. [X-ray telescope mirrors

    NASA Technical Reports Server (NTRS)

    Williams, A. C.

    1982-01-01

    The scattering of X-rays from state-of-the-art polished mirrors is discussed with reference to the requirements of the Advanced X-ray Astrophysics Facility telescope. An experimental set-up is described which allows information to be obtained with subarcsecond resolution. A sample of the data obtained is presented along with a possible theoretical model for its interpretation.

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

    NASA Technical Reports Server (NTRS)

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

    1993-01-01

    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.

  20. Accurate small and wide angle x-ray scattering profiles from atomic models of proteins and nucleic acids

    NASA Astrophysics Data System (ADS)

    Nguyen, Hung T.; Pabit, Suzette A.; Meisburger, Steve P.; Pollack, Lois; Case, David A.

    2014-12-01

    A new method is introduced to compute X-ray solution scattering profiles from atomic models of macromolecules. The three-dimensional version of the Reference Interaction Site Model (RISM) from liquid-state statistical mechanics is employed to compute the solvent distribution around the solute, including both water and ions. X-ray scattering profiles are computed from this distribution together with the solute geometry. We describe an efficient procedure for performing this calculation employing a Lebedev grid for the angular averaging. The intensity profiles (which involve no adjustable parameters) match experiment and molecular dynamics simulations up to wide angle for two proteins (lysozyme and myoglobin) in water, as well as the small-angle profiles for a dozen biomolecules taken from the BioIsis.net database. The RISM model is especially well-suited for studies of nucleic acids in salt solution. Use of fiber-diffraction models for the structure of duplex DNA in solution yields close agreement with the observed scattering profiles in both the small and wide angle scattering (SAXS and WAXS) regimes. In addition, computed profiles of anomalous SAXS signals (for Rb+ and Sr2+) emphasize the ionic contribution to scattering and are in reasonable agreement with experiment. In cases where an absolute calibration of the experimental data at q = 0 is available, one can extract a count of the excess number of waters and ions; computed values depend on the closure that is assumed in the solution of the Ornstein-Zernike equations, with results from the Kovalenko-Hirata closure being closest to experiment for the cases studied here.

  1. Direct Observation of Insulin Association Dynamics with Time-Resolved X-ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rimmerman, Dolev; Leshchev, Denis; Hsu, Darren J.

    Biological functions frequently require protein-protein interactions that involve secondary and tertiary structural perturbation. Here we study protein-protein dissociation and reassociation dynamics in insulin, a model system for protein oligomerization. Insulin dimer dissociation into monomers was induced by a nanosecond temperature-jump (T-jump) of ~8 °C in aqueous solution, and the resulting protein and solvent dynamics were tracked by time-resolved X-ray solution scattering (TRXSS) on time scales of 10 ns to 100 ms. The protein scattering signals revealed the formation of five distinguishable transient species during the association process that deviate from simple two state kinetics. Our results show that the combinationmore » of T-jump pump coupled to TRXSS probe allows for direct tracking of structural dynamics in nonphotoactive proteins.« less

  2. 16th National School on Neutron and X-ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chakoumakos, Bryan; Achilles, Cherie; Cybulskis, Viktor

    Students talk about their experience at the 16th National School on Neutron and X-ray Scattering, or NXS 2014. Jointly conducted by Oak Ridge and Argonne national laboratories, NXS immerses graduate students in national user facilities to learn in a hands-on environment how to use neutrons and X-rays in their research.

  3. 16th National School on Neutron and X-ray Scattering

    ScienceCinema

    Chakoumakos, Bryan; Achilles, Cherie; Cybulskis, Viktor; Gilbert, Ian

    2018-02-14

    Students talk about their experience at the 16th National School on Neutron and X-ray Scattering, or NXS 2014. Jointly conducted by Oak Ridge and Argonne national laboratories, NXS immerses graduate students in national user facilities to learn in a hands-on environment how to use neutrons and X-rays in their research.

  4. X-Ray Form Factor, Attenuation and Scattering Tables

    National Institute of Standards and Technology Data Gateway

    SRD 66 X-Ray Form Factor, Attenuation and Scattering Tables (Web, free access)   This database collects tables and graphs of the form factors, the photoabsorption cross section, and the total attenuation coefficient for any element (Z <= 92).

  5. Elemental-sensitive Detection of the Chemistry in Batteries through Soft X-ray Absorption Spectroscopy and Resonant Inelastic X-ray Scattering.

    PubMed

    Wu, Jinpeng; Sallis, Shawn; Qiao, Ruimin; Li, Qinghao; Zhuo, Zengqing; Dai, Kehua; Guo, Zixuan; Yang, Wanli

    2018-04-17

    Energy storage has become more and more a limiting factor of today's sustainable energy applications, including electric vehicles and green electric grid based on volatile solar and wind sources. The pressing demand of developing high-performance electrochemical energy storage solutions, i.e., batteries, relies on both fundamental understanding and practical developments from both the academy and industry. The formidable challenge of developing successful battery technology stems from the different requirements for different energy-storage applications. Energy density, power, stability, safety, and cost parameters all have to be balanced in batteries to meet the requirements of different applications. Therefore, multiple battery technologies based on different materials and mechanisms need to be developed and optimized. Incisive tools that could directly probe the chemical reactions in various battery materials are becoming critical to advance the field beyond its conventional trial-and-error approach. Here, we present detailed protocols for soft X-ray absorption spectroscopy (sXAS), soft X-ray emission spectroscopy (sXES), and resonant inelastic X-ray scattering (RIXS) experiments, which are inherently elemental-sensitive probes of the transition-metal 3d and anion 2p states in battery compounds. We provide the details on the experimental techniques and demonstrations revealing the key chemical states in battery materials through these soft X-ray spectroscopy techniques.

  6. SMALL ANGLE SCATTERING OF X-RAYS BY PLASTICALLY DEFORMED SINGLE CRYSTALS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Robinson, W.H.; Smoluchowski, R.

    1959-05-01

    The small-angle scattering of x rays from single crystals of magnesium plastically deformed by simple shear was measured in the angular range of 4' to 5 deg . The crystals were subjected to both unidirectional and cyclic shear stresses applied along the STAl 1 2-bar 0! direction. Thin slices of the deformed single crystals were prepared using strainfree cutting and polishing techniques. The thin slices had orientations such that the slip direction was either parallel or perpendicular to the incident x-ray beam in order to observe any anisotropy in the scattering that might be due to dislocations. It was foundmore » that those samples which contained deformation twins within the irradiated volume produced rather large scattered intensity. This scattered intensity is interpreted as being due to double Bragg scattering. The scattered intensity from other specimens was attributed to surface scattering. No evidence for small angle scattering by dislocations was found. (auth)« less

  7. Solution Structures of Highly Active Molecular Ir Water-Oxidation Catalysts from Density Functional Theory Combined with High-Energy X-ray Scattering and EXAFS Spectroscopy.

    PubMed

    Yang, Ke R; Matula, Adam J; Kwon, Gihan; Hong, Jiyun; Sheehan, Stafford W; Thomsen, Julianne M; Brudvig, Gary W; Crabtree, Robert H; Tiede, David M; Chen, Lin X; Batista, Victor S

    2016-05-04

    The solution structures of highly active Ir water-oxidation catalysts are elucidated by combining density functional theory, high-energy X-ray scattering (HEXS), and extended X-ray absorption fine structure (EXAFS) spectroscopy. We find that the catalysts are Ir dimers with mono-μ-O cores and terminal anionic ligands, generated in situ through partial oxidation of a common catalyst precursor. The proposed structures are supported by (1)H and (17)O NMR, EPR, resonance Raman and UV-vis spectra, electrophoresis, etc. Our findings are particularly valuable to understand the mechanism of water oxidation by highly reactive Ir catalysts. Importantly, our DFT-EXAFS-HEXS methodology provides a new in situ technique for characterization of active species in catalytic systems.

  8. Diffraction based method to reconstruct the spectrum of the Thomson scattering x-ray source

    NASA Astrophysics Data System (ADS)

    Chi, Zhijun; Yan, Lixin; Zhang, Zhen; Zhou, Zheng; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Nie, Zan; Zhang, Jie; Du, Yingchao; Hua, Jianfei; Shi, Jiaru; Pai, Chihao; Lu, Wei; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

    2017-04-01

    As Thomson scattering x-ray sources based on the collision of intense laser and relativistic electrons have drawn much attention in various scientific fields, there is an increasing demand for the effective methods to reconstruct the spectrum information of the ultra-short and high-intensity x-ray pulses. In this paper, a precise spectrum measurement method for the Thomson scattering x-ray sources was proposed with the diffraction of a Highly Oriented Pyrolytic Graphite (HOPG) crystal and was demonstrated at the Tsinghua Thomson scattering X-ray source. The x-ray pulse is diffracted by a 15 mm (L) ×15 mm (H)× 1 mm (D) HOPG crystal with 1° mosaic spread. By analyzing the diffraction pattern, both x-ray peak energies and energy spectral bandwidths at different polar angles can be reconstructed, which agree well with the theoretical value and simulation. The higher integral reflectivity of the HOPG crystal makes this method possible for single-shot measurement.

  9. Diffraction based method to reconstruct the spectrum of the Thomson scattering x-ray source.

    PubMed

    Chi, Zhijun; Yan, Lixin; Zhang, Zhen; Zhou, Zheng; Zheng, Lianmin; Wang, Dong; Tian, Qili; Wang, Wei; Nie, Zan; Zhang, Jie; Du, Yingchao; Hua, Jianfei; Shi, Jiaru; Pai, Chihao; Lu, Wei; Huang, Wenhui; Chen, Huaibi; Tang, Chuanxiang

    2017-04-01

    As Thomson scattering x-ray sources based on the collision of intense laser and relativistic electrons have drawn much attention in various scientific fields, there is an increasing demand for the effective methods to reconstruct the spectrum information of the ultra-short and high-intensity x-ray pulses. In this paper, a precise spectrum measurement method for the Thomson scattering x-ray sources was proposed with the diffraction of a Highly Oriented Pyrolytic Graphite (HOPG) crystal and was demonstrated at the Tsinghua Thomson scattering X-ray source. The x-ray pulse is diffracted by a 15 mm (L) ×15 mm (H)× 1 mm (D) HOPG crystal with 1° mosaic spread. By analyzing the diffraction pattern, both x-ray peak energies and energy spectral bandwidths at different polar angles can be reconstructed, which agree well with the theoretical value and simulation. The higher integral reflectivity of the HOPG crystal makes this method possible for single-shot measurement.

  10. Ion charge state distribution effects on elastic X-ray Thomson scattering

    NASA Astrophysics Data System (ADS)

    Iglesias, Carlos A.

    2018-03-01

    Analytic models commonly applied in elastic X-ray Thomson scattering cross-section calculations are used to generate results from a discrete ion charge distribution and an average charge description. Comparisons show that interchanging the order of the averaging procedure can appreciably alter the cross-section, especially for plasmas with partially filled K-shell bound electrons. In addition, two common approximations to describe the free electron density around an ion are shown to yield significantly different elastic X-ray Thomson scattering cross-sections.

  11. Small-scale screening method for low-viscosity antibody solutions using small-angle X-ray scattering.

    PubMed

    Fukuda, Masakazu; Watanabe, Atsushi; Hayasaka, Akira; Muraoka, Masaru; Hori, Yuji; Yamazaki, Tadao; Imaeda, Yoshimi; Koga, Akiko

    2017-03-01

    In this study, we investigated the concentration range in which self-association starts to form in humanized IgG monoclonal antibody (mAb) solutions. Furthermore, on the basis of the results, we developed a practical method of screening for low-viscosity antibody solutions by using small-angle X-ray scattering (SAXS) measurements utilizing small quantities of samples. With lower-viscosity mAb3, self-association was not detected in the range of 1-80mg/mL. With higher-viscosity mAb1, on the other hand, self-association was detected in the range of 10-20mg/mL and was clearly enhanced by a decrease in temperature. The viscosities of mAb solutions at 160, 180, and 200mg/mL at 25°C quantitatively correlated very well with the particle size parameters obtained by SAXS measurements of mAb solutions at 15mg/mL at 5°C. The quantity of mAb sample required for the SAXS measurements was only 0.15mg, which is about one-hundredth of that required for actual viscosity measurements at a high concentration, and such quantities could be available even at an early stage of development. In conclusion, the SAXS analysis method proposed in this study is a valuable tool for the development of concentrated mAb therapeutics with high manufacturability and high usability for subcutaneous injection. Copyright © 2016 Elsevier B.V. All rights reserved.

  12. Focusing polycapillary to reduce parasitic scattering for inelastic x-ray measurements at high pressure

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chow, P., E-mail: pchow@carnegiescience.edu; Xiao, Y. M.; Rod, E.

    2015-07-15

    The double-differential scattering cross-section for the inelastic scattering of x-ray photons from electrons is typically orders of magnitude smaller than that of elastic scattering. With samples 10-100 μm size in a diamond anvil cell at high pressure, the inelastic x-ray scattering signals from samples are obscured by scattering from the cell gasket and diamonds. One major experimental challenge is to measure a clean inelastic signal from the sample in a diamond anvil cell. Among the many strategies for doing this, we have used a focusing polycapillary as a post-sample optic, which allows essentially only scattered photons within its input fieldmore » of view to be refocused and transmitted to the backscattering energy analyzer of the spectrometer. We describe the modified inelastic x-ray spectrometer and its alignment. With a focused incident beam which matches the sample size and the field of view of polycapillary, at relatively large scattering angles, the polycapillary effectively reduces parasitic scattering from the diamond anvil cell gasket and diamonds. Raw data collected from the helium exciton measured by x-ray inelastic scattering at high pressure using the polycapillary method are compared with those using conventional post-sample slit collimation.« less

  13. Experiment and application of soft x-ray grazing incidence optical scattering phenomena

    NASA Astrophysics Data System (ADS)

    Chen, Shuyan; Li, Cheng; Zhang, Yang; Su, Liping; Geng, Tao; Li, Kun

    2017-08-01

    For short wavelength imaging systems,surface scattering effects is one of important factors degrading imaging performance. Study of non-intuitive surface scatter effects resulting from practical optical fabrication tolerances is a necessary work for optical performance evaluation of high resolution short wavelength imaging systems. In this paper, Soft X-ray optical scattering distribution is measured by a soft X-ray reflectometer installed by my lab, for different sample mirrors、wavelength and grazing angle. Then aim at space solar telescope, combining these scattered light distributions, and surface scattering numerical model of grazing incidence imaging system, PSF and encircled energy of optical system of space solar telescope are computed. We can conclude that surface scattering severely degrade imaging performance of grazing incidence systems through analysis and computation.

  14. Fast scattering simulation tool for multi-energy x-ray imaging

    NASA Astrophysics Data System (ADS)

    Sossin, A.; Tabary, J.; Rebuffel, V.; Létang, J. M.; Freud, N.; Verger, L.

    2015-12-01

    A combination of Monte Carlo (MC) and deterministic approaches was employed as a means of creating a simulation tool capable of providing energy resolved x-ray primary and scatter images within a reasonable time interval. Libraries of Sindbad, a previously developed x-ray simulation software, were used in the development. The scatter simulation capabilities of the tool were validated through simulation with the aid of GATE and through experimentation by using a spectrometric CdTe detector. A simple cylindrical phantom with cavities and an aluminum insert was used. Cross-validation with GATE showed good agreement with a global spatial error of 1.5% and a maximum scatter spectrum error of around 6%. Experimental validation also supported the accuracy of the simulations obtained from the developed software with a global spatial error of 1.8% and a maximum error of around 8.5% in the scatter spectra.

  15. Resonant Soft X-ray Scattering of Cellulose Microstructure in Plant Primary Cell Walls

    NASA Astrophysics Data System (ADS)

    Ye, Dan; Kiemle, Sarah N.; Wang, Cheng; Cosgrove, Daniel J.; Gomez, Esther W.; Gomez, Enrique D.

    Cellulosic biomass is the most abundant raw material available for the production of renewable and sustainable biofuels. Breaking down cellulose is the rate-limiting step in economical biofuel production; therefore, a detailed understanding of the microscopic structure of plant cell walls is required to develop efficient biofuel conversion methods. Primary cell walls are key determinants of plant growth and mechanics. Their structure is complex and heterogeneous, making it difficult to elucidate how various components such as pectin, hemicellulose, and cellulose contribute to the overall structure. The electron density of these wall components is similar; such that conventional hard X-ray scattering does not generate enough contrast to resolve the different elements of the polysaccharide network. The chemical specificity of resonant soft X-ray scattering allows contrast to be generated based on differences in chemistry of the different polysaccharides. By varying incident X-ray energies, we have achieved increased scattering contrast between cellulose and other polysaccharides from primary cell walls of onions. By performing scattering at certain energies, features of the network structure of the cell wall are resolved. From the soft X-ray scattering results, we obtained the packing distance of cellulose microfibrils embedded in the polysaccharide network.

  16. Predicting X-ray diffuse scattering from translation–libration–screw structural ensembles

    PubMed Central

    Van Benschoten, Andrew H.; Afonine, Pavel V.; Terwilliger, Thomas C.; Wall, Michael E.; Jackson, Colin J.; Sauter, Nicholas K.; Adams, Paul D.; Urzhumtsev, Alexandre; Fraser, James S.

    2015-01-01

    Identifying the intramolecular motions of proteins and nucleic acids is a major challenge in macromolecular X-ray crystallography. Because Bragg diffraction describes the average positional distribution of crystalline atoms with imperfect precision, the resulting electron density can be compatible with multiple models of motion. Diffuse X-ray scattering can reduce this degeneracy by reporting on correlated atomic displacements. Although recent technological advances are increasing the potential to accurately measure diffuse scattering, computational modeling and validation tools are still needed to quantify the agreement between experimental data and different parameterizations of crystalline disorder. A new tool, phenix.diffuse, addresses this need by employing Guinier’s equation to calculate diffuse scattering from Protein Data Bank (PDB)-formatted structural ensembles. As an example case, phenix.diffuse is applied to translation–libration–screw (TLS) refinement, which models rigid-body displacement for segments of the macromolecule. To enable the calculation of diffuse scattering from TLS-refined structures, phenix.tls_as_xyz builds multi-model PDB files that sample the underlying T, L and S tensors. In the glycerophos­phodiesterase GpdQ, alternative TLS-group partitioning and different motional correlations between groups yield markedly dissimilar diffuse scattering maps with distinct implications for molecular mechanism and allostery. These methods demonstrate how, in principle, X-ray diffuse scattering could extend macromolecular structural refinement, validation and analysis. PMID:26249347

  17. Predicting X-ray diffuse scattering from translation–libration–screw structural ensembles

    DOE PAGES

    Van Benschoten, Andrew H.; Afonine, Pavel V.; Terwilliger, Thomas C.; ...

    2015-07-28

    Identifying the intramolecular motions of proteins and nucleic acids is a major challenge in macromolecular X-ray crystallography. Because Bragg diffraction describes the average positional distribution of crystalline atoms with imperfect precision, the resulting electron density can be compatible with multiple models of motion. Diffuse X-ray scattering can reduce this degeneracy by reporting on correlated atomic displacements. Although recent technological advances are increasing the potential to accurately measure diffuse scattering, computational modeling and validation tools are still needed to quantify the agreement between experimental data and different parameterizations of crystalline disorder. A new tool, phenix.diffuse, addresses this need by employing Guinier'smore » equation to calculate diffuse scattering from Protein Data Bank (PDB)-formatted structural ensembles. As an example case, phenix.diffuse is applied to translation–libration–screw (TLS) refinement, which models rigid-body displacement for segments of the macromolecule. To enable the calculation of diffuse scattering from TLS-refined structures, phenix.tls_as_xyz builds multi-model PDB files that sample the underlying T, L and S tensors. In the glycerophosphodiesterase GpdQ, alternative TLS-group partitioning and different motional correlations between groups yield markedly dissimilar diffuse scattering maps with distinct implications for molecular mechanism and allostery. In addition, these methods demonstrate how, in principle, X-ray diffuse scattering could extend macromolecular structural refinement, validation and analysis.« less

  18. Nonlinear resonance scattering of femtosecond X-ray pulses on atoms in plasmas

    NASA Astrophysics Data System (ADS)

    Rosmej, F. B.; Astapenko, V. A.; Lisitsa, V. S.; Moroz, N. N.

    2017-11-01

    It is shown that for sufficiently short pulses the resonance scattering probability becomes a nonlinear function of the pulse duration. For fs X-ray pulses scattered on atoms in plasmas maxima and minima develop in the nonlinear regime whereas in the limit of long pulses the probability becomes linear and turns over into the standard description of the electromagnetic pulse scattering. Numerical calculations are carried out in terms of a generalized scattering probability for the total time of pulse duration including fine structure splitting and ion Doppler broadening in hot plasmas. For projected X-ray monocycles, the generalized nonlinear approach differs by 1-2 orders of magnitude from the standard theory.

  19. X-band RF gun and linac for medical Compton scattering X-ray source

    NASA Astrophysics Data System (ADS)

    Dobashi, Katsuhito; Uesaka, Mitsuru; Fukasawa, Atsushi; Sakamoto, Fumito; Ebina, Futaro; Ogino, Haruyuki; Urakawa, Junji; Higo, Toshiyasu; Akemoto, Mitsuo; Hayano, Hitoshi; Nakagawa, Keiichi

    2004-12-01

    Compton scattering hard X-ray source for 10-80 keV are under construction using the X-band (11.424 GHz) electron linear accelerator and YAG laser at Nuclear Engineering Research laboratory, University of Tokyo. This work is a part of the national project on the development of advanced compact medical accelerators in Japan. National Institute for Radiological Science is the host institute and U.Tokyo and KEK are working for the X-ray source. Main advantage is to produce tunable monochromatic hard (10-80 keV) X-rays with the intensities of 108-1010 photons/s (at several stages) and the table-top size. Second important aspect is to reduce noise radiation at a beam dump by adopting the deceleration of electrons after the Compton scattering. This realizes one beamline of a 3rd generation SR source at small facilities without heavy shielding. The final goal is that the linac and laser are installed on the moving gantry. We have designed the X-band (11.424 GHz) traveling-wave-type linac for the purpose. Numerical consideration by CAIN code and luminosity calculation are performed to estimate the X-ray yield. X-band thermionic-cathode RF-gun and RDS(Round Detuned Structure)-type X-band accelerating structure are applied to generate 50 MeV electron beam with 20 pC microbunches (104) for 1 microsecond RF macro-pulse. The X-ray yield by the electron beam and Q-switch Nd:YAG laser of 2 J/10 ns is 107 photons/RF-pulse (108 photons/sec at 10 pps). We design to adopt a technique of laser circulation to increase the X-ray yield up to 109 photons/pulse (1010 photons/s). 50 MW X-band klystron and compact modulator have been constructed and now under tuning. The construction of the whole system has started. X-ray generation and medical application will be performed in the early next year.

  20. BioSAXS Sample Changer: a robotic sample changer for rapid and reliable high-throughput X-ray solution scattering experiments

    PubMed Central

    Round, Adam; Felisaz, Franck; Fodinger, Lukas; Gobbo, Alexandre; Huet, Julien; Villard, Cyril; Blanchet, Clement E.; Pernot, Petra; McSweeney, Sean; Roessle, Manfred; Svergun, Dmitri I.; Cipriani, Florent

    2015-01-01

    Small-angle X-ray scattering (SAXS) of macromolecules in solution is in increasing demand by an ever more diverse research community, both academic and industrial. To better serve user needs, and to allow automated and high-throughput operation, a sample changer (BioSAXS Sample Changer) that is able to perform unattended measurements of up to several hundred samples per day has been developed. The Sample Changer is able to handle and expose sample volumes of down to 5 µl with a measurement/cleaning cycle of under 1 min. The samples are stored in standard 96-well plates and the data are collected in a vacuum-mounted capillary with automated positioning of the solution in the X-ray beam. Fast and efficient capillary cleaning avoids cross-contamination and ensures reproducibility of the measurements. Independent temperature control for the well storage and for the measurement capillary allows the samples to be kept cool while still collecting data at physiological temperatures. The Sample Changer has been installed at three major third-generation synchrotrons: on the BM29 beamline at the European Synchrotron Radiation Facility (ESRF), the P12 beamline at the PETRA-III synchrotron (EMBL@PETRA-III) and the I22/B21 beamlines at Diamond Light Source, with the latter being the first commercial unit supplied by Bruker ASC. PMID:25615861

  1. Geant4 simulations of soft proton scattering in X-ray optics. A tentative validation using laboratory measurements

    NASA Astrophysics Data System (ADS)

    Fioretti, Valentina; Mineo, Teresa; Bulgarelli, Andrea; Dondero, Paolo; Ivanchenko, Vladimir; Lei, Fan; Lotti, Simone; Macculi, Claudio; Mantero, Alfonso

    2017-12-01

    Low energy protons (< 300 keV) can enter the field of view of X-ray telescopes, scatter on their mirror surfaces at small incident angles, and deposit energy on the detector. This phenomenon can cause intense background flares at the focal plane decreasing the mission observing time (e.g. the XMM-Newton mission) or in the most extreme cases, damaging the X-ray detector. A correct modelization of the physics process responsible for the grazing angle scattering processes is mandatory to evaluate the impact of such events on the performance (e.g. observation time, sensitivity) of future X-ray telescopes as the ESA ATHENA mission. The Remizovich model describes particles reflected by solids at glancing angles in terms of the Boltzmann transport equation using the diffuse approximation and the model of continuous slowing down in energy. For the first time this solution, in the approximation of no energy losses, is implemented, verified, and qualitatively validated on top of the Geant4 release 10.2, with the possibility to add a constant energy loss to each interaction. This implementation is verified by comparing the simulated proton distribution to both the theoretical probability distribution and with independent ray-tracing simulations. Both the new scattering physics and the Coulomb scattering already built in the official Geant4 distribution are used to reproduce the latest experimental results on grazing angle proton scattering. At 250 keV multiple scattering delivers large proton angles and it is not consistent with the observation. Among the tested models, the single scattering seems to better reproduce the scattering efficiency at the three energies but energy loss obtained at small scattering angles is significantly lower than the experimental values. In general, the energy losses obtained in the experiment are higher than what obtained by the simulation. The experimental data are not completely representative of the soft proton scattering experienced by

  2. Visible light scatter measurements of the Advanced X-ray Astronomical Facility /AXAF/ mirror samples

    NASA Technical Reports Server (NTRS)

    Griner, D. B.

    1981-01-01

    NASA is studying the properties of mirror surfaces for X-ray telescopes, the data of which will be used to develop the telescope system for the Advanced X-ray Astronomical Facility. Visible light scatter measurements, using a computer controlled scanner, are made of various mirror samples to determine surface roughness. Total diffuse scatter is calculated using numerical integration techniques and used to estimate the rms surface roughness. The data measurements are then compared with X-ray scatter measurements of the same samples. A summary of the data generated is presented, along with graphs showing changes in scatter on samples before and after cleaning. Results show that very smooth surfaces can be polished on the common substrate materials (from 2 to 10 Angstroms), and nickel appears to give the lowest visible light scatter.

  3. Electron-ion collision-frequency for x-ray Thomson scattering in dense plasmas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Faussurier, Gérald, E-mail: gerald.faussurier@cea.fr; Blancard, Christophe

    2016-01-15

    Two methods are presented to calculate the electron-ion collision-frequency in dense plasmas using an average-atom model. The first one is based on the Kubo-Greenwood approach. The second one uses the Born and Lenard-Balescu approximations. The two methods are used to calculate x-ray Thomson scattering spectra. Illustrations are shown for dense beryllium and aluminum plasmas. Comparisons with experiment are presented in the case of an x-ray Thomson scattering spectrum.

  4. Inelastic X-ray Scattering Measurements of Ionization in Warm, Dense Matter

    NASA Astrophysics Data System (ADS)

    Davis, Paul F.

    In this work we demonstrate spectrally resolved x-ray scattering from electron-plasma waves in shock-compressed deuterium and proton-heated matter. Because the spectral signature of inelastic x-ray scattering is strongly dependent on the free electron density of the system, it is used to infer ionization in dynamically heated samples. Using 2-6 ns, 500 J laser pulses from LLNL's Janus laser, we shocked liquid deuterium to pressures approaching 50 GPa, reaching compressions of 4 times liquid density. A second laser produced intense 2 keV x-rays. By collecting and spectrally dispersing forward scattered photons at 45°, the onset of ionization was detected at compressions of about 3 times in the form of plasmon oscillations. Backscattered x-rays bolstered this observation by measuring the free electron distribution through Compton scattering. Comparison with simulations shows very close agreement between the pressure dependence of ionization and molecular dissociation in dynamically compressed deuterium. In a second set of experiments, a 10 ps, 200 J Titan laser pulse was split into two beams. One created a stream of MeV protons to heat samples of boron and boron-nitride and the other pumped 4.5 keV K-alpha radiation in a titanium foil to probe the hot target. We observed scattered x-rays 300 ps after heating, noting a strong difference in average ionization between the two target materials at temperatures of 16 eV and very similar mass densities. Comparison with electron structure calculations suggests that this difference is due to a persistence of long-range ion structure in BN resulting in high-temperature band structure. These results underscore the importance of understanding the complex electron structure of materials even at electron-volt temperatures and gigapascal pressures. Our results provide new data to guide the theoretical modeling of warm, dense matter important to understanding giant planets and inertial fusion targets.

  5. Real-time, ray casting-based scatter dose estimation for c-arm x-ray system.

    PubMed

    Alnewaini, Zaid; Langer, Eric; Schaber, Philipp; David, Matthias; Kretz, Dominik; Steil, Volker; Hesser, Jürgen

    2017-03-01

    Dosimetric control of staff exposure during interventional procedures under fluoroscopy is of high relevance. In this paper, a novel ray casting approximation of radiation transport is presented and the potential and limitation vs. a full Monte Carlo transport and dose measurements are discussed. The x-ray source of a Siemens Axiom Artix C-arm is modeled by a virtual source model using single Gaussian-shaped source. A Geant4-based Monte Carlo simulation determines the radiation transport from the source to compute scatter from the patient, the table, the ceiling and the floor. A phase space around these scatterers stores all photon information. Only those photons are traced that hit a surface of phantom that represents medical staff in the treatment room, no indirect scattering is considered; and a complete dose deposition on the surface is calculated. To evaluate the accuracy of the approximation, both experimental measurements using Thermoluminescent dosimeters (TLDs) and a Geant4-based Monte Carlo simulation of dose depositing for different tube angulations of the C-arm from cranial-caudal angle 0° and from LAO (Left Anterior Oblique) 0°-90° are realized. Since the measurements were performed on both sides of the table, using the symmetry of the setup, RAO (Right Anterior Oblique) measurements were not necessary. The Geant4-Monte Carlo simulation agreed within 3% with the measured data, which is within the accuracy of measurement and simulation. The ray casting approximation has been compared to TLD measurements and the achieved percentage difference was -7% for data from tube angulations 45°-90° and -29% from tube angulations 0°-45° on the side of the x-ray source, whereas on the opposite side of the x-ray source, the difference was -83.8% and -75%, respectively. Ray casting approximation for only LAO 90° was compared to a Monte Carlo simulation, where the percentage differences were between 0.5-3% on the side of the x-ray source where the highest dose

  6. X-ray Magnetic Scattering From Surfaces^*

    NASA Astrophysics Data System (ADS)

    Gibbs, Doon

    1997-03-01

    In the last several years, there have been continuing efforts to probe long-ranged magnetic order at surfaces by x-ray and neutron diffraction, following many earlier studies by low energy electron diffraction. The main motivation has been to discover how bulk magnetic structures are modified near a surface, where the crystal symmetry is broken. In this talk, we describe x-ray scattering studies of the magnetic structure observed near the (001) surface of the antiferromagnet uranium dioxide.(G. M. Watson, Doon Gibbs, G. H. Lander, B. D. Gaulin, L.E. Berman, Hj. Matzke and W. Ellis, Phys. Rev. Lett. 77), 751 (1996). Within about 50 Åof the surface, the intensity of the magnetic scattering decreases continuously as the bulk Neel temperature is approached from below. This contrasts with the bulk magnetic ordering transition which is discontinuous. Recent measurements of the specular magnetic reflectivity suggest that the width of the magnetic interface diverges as a power-law in reduced temperature reminiscent of surface induced disorder. Related experiments concerned with magnetic crystallography of Co_3-Pt(111) surfaces(S. Ferrer, P. Fajardo, F. de Bergevin, J. Alvarez, X. Torrelles, H. A. van der Vegt and V. H. Etgens, Phys. Rev. Lett. 77), 747 (1996). and interfacial magnetic roughness of Co/Cu multilayers(J. F. MacKay, C. Teichert, D.E. Savage and M.G. Lagally, Phys. Rev. Lett. 77), 3925 (1996). will also be discussed. ^* Work at Brookhaven National Laboratory is supported by the U.S. DOE under Contract No. DE-AC02-CH7600016.

  7. The use of short and wide x-ray pulses for time-of-flight x-ray Compton Scatter Imaging in cargo security

    NASA Astrophysics Data System (ADS)

    Calvert, Nick; Betcke, Marta M.; Cresswell, John R.; Deacon, Alick N.; Gleeson, Anthony J.; Judson, Daniel S.; Mason, Peter; McIntosh, Peter A.; Morton, Edward J.; Nolan, Paul J.; Ollier, James; Procter, Mark G.; Speller, Robert D.

    2015-05-01

    Using a short pulse width x-ray source and measuring the time-of-flight of photons that scatter from an object under inspection allows for the point of interaction to be determined, and a profile of the object to be sampled along the path of the beam. A three dimensional image can be formed by interrogating the entire object. Using high energy x rays enables the inspection of cargo containers with steel walls, in the search for concealed items. A longer pulse width x-ray source can also be used with deconvolution techniques to determine the points of interaction. We present time-of-flight results from both short (picosecond) width and long (hundreds of nanoseconds) width x-ray sources, and show that the position of scatter can be localised with a resolution of 2 ns, equivalent to 30 cm, for a 3 cm thick plastic test object.

  8. X-ray Thomson scattering measurement of temperature in warm dense carbon

    DOE PAGES

    Falk, Katerina; Fryer, C. L.; Gamboa, E. J.; ...

    2016-11-22

    Here, a novel platform to measure the equation of state using a combination of diagnostics, where the spectrally resolved x-ray Thomson scattering (XRTS) is used to obtain accurate temperature measurements of warm dense matter (WDM) was developed for the OMEGA laser facility. OMEGA laser beams have been used to drive strong shocks in carbon targets creating WDM and generating the Ni He-alpha x-ray probe used for XRTS. Additional diagnostics including x-ray radiography, velocity interferometry and streaked optical pyrometry provided complementary measurements of density and pressure. The WDM regime of near solid density and moderate temperatures (1–100 eV) is a challengingmore » yet important area of research in inertial confinement fusion and astrophysics. This platform has been used to study off-Hugoniot states of shock-released diamond and graphite at pressures between 1 and 10 Mbar and temperatures between 5 and 15 eV as well as first x-ray Thomson scattering data from shocked low density CH foams reaching five times compression and temperatures of 20–30 eV.« less

  9. Superhydrophobic surfaces allow probing of exosome self organization using X-ray scattering

    NASA Astrophysics Data System (ADS)

    Accardo, Angelo; Tirinato, Luca; Altamura, Davide; Sibillano, Teresa; Giannini, Cinzia; Riekel, Christian; di Fabrizio, Enzo

    2013-02-01

    Drops of exosome dispersions from healthy epithelial colon cell line and colorectal cancer cells were dried on a superhydrophobic PMMA substrate. The residues were studied by small- and wide-angle X-ray scattering using both a synchrotron radiation micrometric beam and a high-flux table-top X-ray source. Structural differences between healthy and cancerous cells were detected in the lamellar lattices of the exosome macro-aggregates.Drops of exosome dispersions from healthy epithelial colon cell line and colorectal cancer cells were dried on a superhydrophobic PMMA substrate. The residues were studied by small- and wide-angle X-ray scattering using both a synchrotron radiation micrometric beam and a high-flux table-top X-ray source. Structural differences between healthy and cancerous cells were detected in the lamellar lattices of the exosome macro-aggregates. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr34032e

  10. Ab initio studies of ultrafast x-ray scattering of the photodissociation of iodine

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Debnarova, Andrea; Techert, Simone; Schmatz, Stefan

    2010-09-28

    We computationally examine various aspects of the reaction dynamics of the photodissociation and recombination of molecular iodine. We use our recently proposed formalism to calculate time-dependent x-ray scattering signal changes from first principles. Different aspects of the dynamics of this prototypical reaction are studied, such as coherent and noncoherent processes, features of structural relaxation that are periodic in time versus nonperiodic dissociative processes, as well as small electron density changes caused by electronic excitation, all with respect to x-ray scattering. We can demonstrate that wide-angle x-ray scattering offers a possibility to study the changes in electron densities in nonperiodic systems,more » which render it a suitable technique for the investigation of chemical reactions from a structural dynamics point of view.« less

  11. Use of dynamic light scattering and small-angle X-ray scattering to characterize new surfactants in solution conditions for membrane-protein crystallization

    PubMed Central

    Dahani, Mohamed; Barret, Laurie-Anne; Raynal, Simon; Jungas, Colette; Pernot, Pétra; Polidori, Ange; Bonneté, Françoise

    2015-01-01

    The structural and interactive properties of two novel hemifluorinated surfactants, F2H9-β-M and F4H5-β-M, the syntheses of which were based on the structure and hydrophobicity of the well known dodecyl-β-maltoside (DD-β-M), are described. The shape of their micellar assemblies was characterized by small-angle X-ray scattering and their intermicellar inter­actions in crystallizing conditions were measured by dynamic light scattering. Such information is essential for surfactant phase-diagram determination and membrane-protein crystallization. PMID:26144228

  12. X-ray Thomson scattering measurements of temperature and density from multi-shocked CH capsules

    DOE PAGES

    Fletcher, L. B.; Glenzer, S. H.; Kritcher, A.; ...

    2013-05-24

    Proof-of-principle measurements of the electron densities, temperatures, and ionization states of spherically compressed multi-shocked CH (polystyrene) capsules have been achieved using spectrally resolved x-ray Thomson scattering. A total energy of 13.5 kJ incident on target is used to compress a 70 μm thick CH shell above solid-mass density using three coalescing shocks. Separately, a laser-produced zinc He-α x-ray source at 9 keV delayed 200 ps-800 ps after maximum compression is used to probe the plasma in the non-collective scattering regime. The data show that x-ray Thomson scattering enables a complete description of the time-dependent hydrodynamic evolution of shock-compressed CH capsules,more » with a maximum measured density of ρ > 6 g cm –3. Additionally, the results demonstrate that accurate measurements of x-ray scattering from bound-free transitions in the CH plasma demonstrate strong evidence that continuum lowering is the primary ionization mechanism of carbon L-shell electrons.« less

  13. Butterfly deformation modes in a photoexcited pyrazolate-bridged Pt complex measured by time-resolved x-ray scattering in solution

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Haldrup, Kristoffer; Dohn, Asmus O.; Shelby, Megan L.

    2016-08-27

    Pyrazolate-bridged di-nuclear Pt complexes represent a series of molecules with tunable absorption and emission properties that can be directly modulated by structural factors, such as the Pt-Pt distance. However, direct experimental information regarding the structure of the emissive triplet excited state has remained scarce. Using time-resolved wide angle X-ray scattering (WAXS), the molecular structure of the triplet excited state for one of the complexes [Pt(ppy)(μ-tBu 2pz)] 2 was obtained in a dilute (0.5 mM) toluene solution utilizing the monochromatic X-ray beamline 11IDD of the Advanced Photon Source. The excited state structural analysis was carried out based on the results frommore » both transient WAXS measurements and DFT calculations to shed light on the primary structural changes, in particular the Pt-Pt distance and ligand rotation taking place following the photo-excitation of [Pt(ppy)(μ-tBu 2pz)] 2 in toluene solution. We find that in the triplet excited state a pronounced contraction along the Pt-Pt axis has taken place accompanied by rotational motions of ppy ligands toward one another. Our results suggest that the contraction is larger than what has previously been reported, but are in good agreement with recent theoretical efforts and suggest the ppy moieties as targets for rational synthesis aimed at tuning the excited-state structure and properties« less

  14. Analyzing For Light Elements By X-Ray Scattering

    NASA Technical Reports Server (NTRS)

    Ross, H. Richard

    1993-01-01

    Nondestructive method of determining concentrations of low-atomic-number elements in liquids and solids involves measurements of Compton and Rayleigh scattering of x rays. Applied in quantitative analysis of low-atomic-number constituents of alloys, of contaminants and corrosion products on surfaces of alloys, and of fractions of hydrogen in plastics, oils, and solvents.

  15. The Discovery of an Evolving Dust Scattered X-ray Halo Around GRB 031203

    NASA Technical Reports Server (NTRS)

    Vaughan, S.; Willingale, R.; OBrien, P. T.; Osborne, J. P.; Reeves, J. N.; Levan, A. J.; Watson, M. G.; Tedds, J. A.; Watson, D.; Santos-Lleo, M.

    2003-01-01

    We report the first detection of a time-dependent, dust-scattered X-ray halo around a gamma-ray burst. GRB3 031203 was observed by XMM-Newton starting six hours after the burst. The halo appeared as concentric ring-like structures centered on the GRB location. The radii of these structures increased with time as t(sup 1/2), consistent with small-angle X-ray scattering caused by a large column of dust along the line of sight to a cosmologically distant GRB. The rings are due to dust concentrated in two distinct slabs in the Galaxy located at distances of 880 and 1390 pc, consistent with known Galactic features. The halo brightness implies an initial soft X-ray pulse consistent with the observed GRB.

  16. Preparing Monodisperse Macromolecular Samples for Successful Biological Small-Angle X-ray and Neutron Scattering Experiments

    PubMed Central

    Jeffries, Cy M.; Graewert, Melissa A.; Blanchet, Clément E.; Langley, David B.; Whitten, Andrew E.; Svergun, Dmitri I

    2017-01-01

    Small-angle X-ray and neutron scattering (SAXS and SANS) are techniques used to extract structural parameters and determine the overall structures and shapes of biological macromolecules, complexes and assemblies in solution. The scattering intensities measured from a sample contain contributions from all atoms within the illuminated sample volume including the solvent and buffer components as well as the macromolecules of interest. In order to obtain structural information, it is essential to prepare an exactly matched solvent blank so that background scattering contributions can be accurately subtracted from the sample scattering to obtain the net scattering from the macromolecules in the sample. In addition, sample heterogeneity caused by contaminants, aggregates, mismatched solvents, radiation damage or other factors can severely influence and complicate data analysis so it is essential that the samples are pure and monodisperse for the duration of the experiment. This Protocol outlines the basic physics of SAXS and SANS and reveals how the underlying conceptual principles of the techniques ultimately ‘translate’ into practical laboratory guidance for the production of samples of sufficiently high quality for scattering experiments. The procedure describes how to prepare and characterize protein and nucleic acid samples for both SAXS and SANS using gel electrophoresis, size exclusion chromatography and light scattering. Also included are procedures specific to X-rays (in-line size exclusion chromatography SAXS) and neutrons, specifically preparing samples for contrast matching/variation experiments and deuterium labeling of proteins. PMID:27711050

  17. Thin film growth studies using time-resolved x-ray scattering

    NASA Astrophysics Data System (ADS)

    Kowarik, Stefan

    2017-02-01

    Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

  18. Thin film growth studies using time-resolved x-ray scattering.

    PubMed

    Kowarik, Stefan

    2017-02-01

    Thin-film growth is important for novel functional materials and new generations of devices. The non-equilibrium growth physics involved is very challenging, because the energy landscape for atomic scale processes is determined by many parameters, such as the diffusion and Ehrlich-Schwoebel barriers. We review the in situ real-time techniques of x-ray diffraction (XRD), x-ray growth oscillations and diffuse x-ray scattering (GISAXS) for the determination of structure and morphology on length scales from Å to µm. We give examples of time resolved growth experiments mainly from molecular thin film growth, but also highlight growth of inorganic materials using molecular beam epitaxy (MBE) and electrochemical deposition from liquids. We discuss how scaling parameters of rate equation models and fundamental energy barriers in kinetic Monte Carlo methods can be determined from fits of the real-time x-ray data.

  19. Density Determination of Metallic Melts from Diffuse X-Ray Scattering

    NASA Astrophysics Data System (ADS)

    Brauser, N.; Davis, A.; Greenberg, E.; Prakapenka, V. B.; Campbell, A.

    2017-12-01

    Liquids comprise several important structural components of the deep Earth, for example, the present outer core and a hypothesized magma ocean early in Earth history. However, the physical properties of the constituent materials of these structures at high pressures and temperatures are less well constrained than their crystalline counterparts. Determination of the physical properties of these liquids can inform geophysical models of the composition and structure of the Earth, but methods for studying the physical properties of liquids at high pressure and temperatures are underdeveloped. One proposed method for direct determination of density of a melt requires analysis of the diffuse scattered X-ray signal of the liquid. Among the challenges to applying this technique to high-pressure melts within a laser heated diamond anvil cell are the low signal-to-noise ratio and overlapping diffraction peaks from the crystalline components of the sample assembly interfering with the diffuse scattering from the liquid. Recent advances in instrumentation at synchrotron X-ray sources have made this method more accessible for determination of density of melted material. In this work we present the technique and report the densities of three high-pressure melts of the FCC metals iron, nickel, and gold derived from diffuse scattered X-ray spectra collected from in situ laser-heated diamond anvil cell synchrotron experiments. The results are compared to densities derived from shock wave experiments.

  20. Creation of X-Ray Transparency of Matter by Stimulated Elastic Forward Scattering.

    PubMed

    Stöhr, J; Scherz, A

    2015-09-04

    X-ray absorption by matter has long been described by the famous Beer-Lambert law. Here, we show how this fundamental law needs to be modified for high-intensity coherent x-ray pulses, now available at x-ray free electron lasers, due to the onset of stimulated elastic forward scattering. We present an analytical expression for the modified polarization-dependent Beer-Lambert law for the case of resonant core-to-valence electronic transitions and incident transform limited x-ray pulses. Upon transmission through a solid, the resonant absorption and dichroic contrasts are found to vanish with increasing x-ray intensity, with the stimulation threshold lowered by orders of magnitude through a resonant superradiantlike effect. Our results have broad implications for the study of matter with x-ray lasers.

  1. Creation of X-Ray Transparency of Matter by Stimulated Elastic Forward Scattering

    NASA Astrophysics Data System (ADS)

    Stöhr, J.; Scherz, A.

    2015-09-01

    X-ray absorption by matter has long been described by the famous Beer-Lambert law. Here, we show how this fundamental law needs to be modified for high-intensity coherent x-ray pulses, now available at x-ray free electron lasers, due to the onset of stimulated elastic forward scattering. We present an analytical expression for the modified polarization-dependent Beer-Lambert law for the case of resonant core-to-valence electronic transitions and incident transform limited x-ray pulses. Upon transmission through a solid, the resonant absorption and dichroic contrasts are found to vanish with increasing x-ray intensity, with the stimulation threshold lowered by orders of magnitude through a resonant superradiantlike effect. Our results have broad implications for the study of matter with x-ray lasers.

  2. Studies of electrode structures and dynamics using coherent X-ray scattering and imaging

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    You, H.; Liu, Y.; Ulvestad, A.

    2017-08-01

    Electrochemical systems studied in situ with advanced surface X-ray scattering techniques are reviewed. The electrochemical systems covered include interfaces of single-crystals and nanocrystals with respect to surface modification, aqueous dissolution, surface reconstruction, and electrochemical double layers. An emphasis will be given on recent results by coherent X-ray techniques such as X-ray photon correlation spectroscopy, Bragg coherent diffraction imaging, and surface ptychography.

  3. Advancing X-ray scattering metrology using inverse genetic algorithms.

    PubMed

    Hannon, Adam F; Sunday, Daniel F; Windover, Donald; Kline, R Joseph

    2016-01-01

    We compare the speed and effectiveness of two genetic optimization algorithms to the results of statistical sampling via a Markov chain Monte Carlo algorithm to find which is the most robust method for determining real space structure in periodic gratings measured using critical dimension small angle X-ray scattering. Both a covariance matrix adaptation evolutionary strategy and differential evolution algorithm are implemented and compared using various objective functions. The algorithms and objective functions are used to minimize differences between diffraction simulations and measured diffraction data. These simulations are parameterized with an electron density model known to roughly correspond to the real space structure of our nanogratings. The study shows that for X-ray scattering data, the covariance matrix adaptation coupled with a mean-absolute error log objective function is the most efficient combination of algorithm and goodness of fit criterion for finding structures with little foreknowledge about the underlying fine scale structure features of the nanograting.

  4. Non-resonant inelastic x-ray scattering spectra of lithiated titanium oxides for battery applications

    NASA Astrophysics Data System (ADS)

    Nagle, Kenneth; Balasubramanian, Mali; Johnson, Christopher; Seidler, Gerald; Belharouak, Ilias

    2008-03-01

    Although lithium-ion batteries now see widespread use, there remain considerable questions concerning the basic solid state chemistry of both electrodes. Improved understanding of the local electronic structure, particularly the mechanism of charge transfer upon insertion and removal of lithium, could lead to innovation in battery design and improved performance. We present non-resonant inelastic x-ray scattering (NRIXS) spectra from 2p initial states in titanium; these spectra are among the first recorded for such states in a transition metal. These spectra were obtained using the lower energy resolution inelastic x-ray scattering (LERIX) spectrometer, which is capable of making simultaneous measurements at nineteen values of momentum transfer. We demonstrate the ability to obtain soft x-ray absorption-like information using a bulk-sensitive, hard x-ray technique. In addition, at high momentum transfer NRIXS provides information about non-dipole transitions that are inaccessible by soft x-ray spectroscopic methods.

  5. Characterizing the behavior of scattered radiation in multi-energy x-ray imaging

    NASA Astrophysics Data System (ADS)

    Sossin, Artur; Rebuffel, V.; Tabary, J.; Létang, J. M.; Freud, N.; Verger, L.

    2017-04-01

    Scattered radiation results in various undesirable effects in medical diagnostics, non-destructive testing (NDT) and security x-ray imaging. Despite numerous studies characterizing this phenomenon and its effects, the knowledge of its behavior in the energy domain remains limited. The present study aims at summarizing some key insights on scattered radiation originating from the inspected object. In addition, various simulations and experiments with limited collimation on both simplified and realistic phantoms were conducted in order to study scatter behavior in multi-energy x-ray imaging. Results showed that the spectrum shape of the scatter component can be considered preserved in the first approximation across the image plane for various acquisition geometries and phantoms. The variations exhibited by the scatter spectrum were below 10% for most examined cases. Furthermore, the corresponding spectrum shape proved to be also relatively invariant for different experimental angular projections of one of the examined phantoms. The observed property of scattered radiation can potentially lead to the decoupling of spatial and energy scatter components, which can in turn enable speed ups in scatter simulations and reduce the complexity of scatter correction.

  6. Computational time-resolved and resonant x-ray scattering of strongly correlated materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bansil, Arun

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source, literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspectsmore » of this grand challenge of x-ray science. In particular, our Collaborative Research Team (CRT) focused on developing viable computational schemes for modeling x-ray scattering and photoemission spectra of strongly correlated materials in the time-domain. The vast arsenal of formal/numerical techniques and approaches encompassed by the members of our CRT were brought to bear through appropriate generalizations and extensions to model the pumped state and the dynamics of this non-equilibrium state, and how it can be probed via x-ray absorption (XAS), emission (XES), resonant and non-resonant x-ray scattering, and photoemission processes. We explored the conceptual connections between the time-domain problems and other second-order spectroscopies, such as resonant inelastic x-ray scattering (RIXS) because RIXS may be effectively thought of as a pump-probe experiment in which the incoming photon acts as the pump, and the fluorescent decay is the probe. Alternatively, when the core-valence interactions are strong, one can view K-edge RIXS for example, as the dynamic response of the material to the transient presence of a strong core-hole potential. Unlike an actual pump-probe experiment, here there is no mechanism for adjusting the time-delay between the pump and the probe. However, the core hole

  7. Imaging Molecular Motion: Femtosecond X-Ray Scattering of an Electrocyclic Chemical Reaction

    NASA Astrophysics Data System (ADS)

    Minitti, M. P.; Budarz, J. M.; Kirrander, A.; Robinson, J. S.; Ratner, D.; Lane, T. J.; Zhu, D.; Glownia, J. M.; Kozina, M.; Lemke, H. T.; Sikorski, M.; Feng, Y.; Nelson, S.; Saita, K.; Stankus, B.; Northey, T.; Hastings, J. B.; Weber, P. M.

    2015-06-01

    Structural rearrangements within single molecules occur on ultrafast time scales. Many aspects of molecular dynamics, such as the energy flow through excited states, have been studied using spectroscopic techniques, yet the goal to watch molecules evolve their geometrical structure in real time remains challenging. By mapping nuclear motions using femtosecond x-ray pulses, we have created real-space representations of the evolving dynamics during a well-known chemical reaction and show a series of time-sorted structural snapshots produced by ultrafast time-resolved hard x-ray scattering. A computational analysis optimally matches the series of scattering patterns produced by the x rays to a multitude of potential reaction paths. In so doing, we have made a critical step toward the goal of viewing chemical reactions on femtosecond time scales, opening a new direction in studies of ultrafast chemical reactions in the gas phase.

  8. Imaging Molecular Motion: Femtosecond X-Ray Scattering of an Electrocyclic Chemical Reaction.

    PubMed

    Minitti, M P; Budarz, J M; Kirrander, A; Robinson, J S; Ratner, D; Lane, T J; Zhu, D; Glownia, J M; Kozina, M; Lemke, H T; Sikorski, M; Feng, Y; Nelson, S; Saita, K; Stankus, B; Northey, T; Hastings, J B; Weber, P M

    2015-06-26

    Structural rearrangements within single molecules occur on ultrafast time scales. Many aspects of molecular dynamics, such as the energy flow through excited states, have been studied using spectroscopic techniques, yet the goal to watch molecules evolve their geometrical structure in real time remains challenging. By mapping nuclear motions using femtosecond x-ray pulses, we have created real-space representations of the evolving dynamics during a well-known chemical reaction and show a series of time-sorted structural snapshots produced by ultrafast time-resolved hard x-ray scattering. A computational analysis optimally matches the series of scattering patterns produced by the x rays to a multitude of potential reaction paths. In so doing, we have made a critical step toward the goal of viewing chemical reactions on femtosecond time scales, opening a new direction in studies of ultrafast chemical reactions in the gas phase.

  9. Simbol-X Mirror Module Thermal Shields: II-Small Angle X-Ray Scattering Measurements

    NASA Astrophysics Data System (ADS)

    Barbera, M.; Ayers, T.; Collura, A.; Nasillo, G.; Pareschi, G.; Tagliaferri, G.

    2009-05-01

    The formation flight configuration of the Simbol-X mission implies that the X-ray mirror module will be open to Space on both ends. In order to reduce the power required to maintain the thermal stability and, therefore, the high angular resolution of the shell optics, a thin foil thermal shield will cover the mirror module. Different options are presently being studied for the foil material of these shields. We report results of an experimental investigation conducted to verify that the scattering of X-rays, by interaction with the thin foil material of the thermal shield, will not significantly affect the performances of the telescope.

  10. Nonlinear X-Ray and Auger Spectroscopy at X-Ray Free-Electron Laser Sources

    NASA Astrophysics Data System (ADS)

    Rohringer, Nina

    2015-05-01

    X-ray free-electron lasers (XFELs) open the pathway to transfer non-linear spectroscopic techniques to the x-ray domain. A promising all x-ray pump probe technique is based on coherent stimulated electronic x-ray Raman scattering, which was recently demonstrated in atomic neon. By tuning the XFEL pulse to core-excited resonances, a few seed photons in the spectral tail of the XFEL pulse drive an avalanche of resonant inelastic x-ray scattering events, resulting in exponential amplification of the scattering signal by of 6-7 orders of magnitude. Analysis of the line profile of the emitted radiation permits to demonstrate the cross over from amplified spontaneous emission to coherent stimulated resonance scattering. In combination with statistical covariance mapping, a high-resolution spectrum of the resonant inelastic scattering process can be obtained, opening the path to coherent stimulated x-ray Raman spectroscopy. An extension of these ideas to molecules and a realistic feasibility study of stimulated electronic x-ray Raman scattering in CO will be presented. Challenges to realizing stimulated electronic x-ray Raman scattering at present-day XFEL sources will be discussed, corroborated by results of a recent experiment at the LCLS XFEL. Due to the small gain cross section in molecular targets, other nonlinear spectroscopic techniques such as nonlinear Auger spectroscopy could become a powerful alternative. Theory predictions of a novel pump probe technique based on resonant nonlinear Auger spectroscopic will be discussed and the method will be compared to stimulated x-ray Raman spectroscopy.

  11. Quantitative Correlation between Viscosity of Concentrated MAb Solutions and Particle Size Parameters Obtained from Small-Angle X-ray Scattering.

    PubMed

    Fukuda, Masakazu; Moriyama, Chifumi; Yamazaki, Tadao; Imaeda, Yoshimi; Koga, Akiko

    2015-12-01

    To investigate the relationship between viscosity of concentrated MAb solutions and particle size parameters obtained from small-angle X-ray scattering (SAXS). The viscosity of three MAb solutions (MAb1, MAb2, and MAb3; 40-200 mg/mL) was measured by electromagnetically spinning viscometer. The protein interactions of MAb solutions (at 60 mg/mL) was evaluated by SAXS. The phase behavior of 60 mg/mL MAb solutions in a low-salt buffer was observed after 1 week storage at 25°C. The MAb1 solutions exhibited the highest viscosity among the three MAbs in the buffer containing 50 mM NaCl. Viscosity of MAb1 solutions decreased with increasing temperature, increasing salt concentration, and addition of amino acids. Viscosity of MAb1 solutions was lowest in the buffer containing histidine, arginine, and aspartic acid. Particle size parameters obtained from SAXS measurements correlated very well with the viscosity of MAb solutions at 200 mg/mL. MAb1 exhibited liquid-liquid phase separation at a low salt concentration. Simultaneous addition of basic and acidic amino acids effectively suppressed intermolecular attractive interactions and decreased viscosity of MAb1 solutions. SAXS can be performed using a small volume of samples; therefore, the particle size parameters obtained from SAXS at intermediate protein concentration could be used to screen for low viscosity antibodies in the early development stage.

  12. Coherent amplification of X-ray scattering from meso-structures

    DOE PAGES

    Lhermitte, Julien R.; Stein, Aaron; Tian, Cheng; ...

    2017-07-10

    Small-angle X-ray scattering (SAXS) often includes an unwanted background, which increases the required measurement time to resolve the sample structure. This is undesirable in all experiments, and may make measurement of dynamic or radiation-sensitive samples impossible. Here, we demonstrate a new technique, applicable when the scattering signal is background-dominated, which reduces the requisite exposure time. Our method consists of exploiting coherent interference between a sample with a designed strongly scattering `amplifier'. A modified angular correlation function is used to extract the symmetry of the interference term; that is, the scattering arising from the interference between the amplifier and the sample.more » This enables reconstruction of the sample's symmetry, despite the sample scattering itself being well below the intensity of background scattering. Thus, coherent amplification is used to generate a strong scattering term (well above background), from which sample scattering is inferred. We validate this method using lithographically defined test samples.« less

  13. Evolution of elastic x-ray scattering in laser-shocked warm dense lithium.

    PubMed

    Kugland, N L; Gregori, G; Bandyopadhyay, S; Brenner, C M; Brown, C R D; Constantin, C; Glenzer, S H; Khattak, F Y; Kritcher, A L; Niemann, C; Otten, A; Pasley, J; Pelka, A; Roth, M; Spindloe, C; Riley, D

    2009-12-01

    We have studied the dynamics of warm dense Li with near-elastic x-ray scattering. Li foils were heated and compressed using shock waves driven by 4-ns-long laser pulses. Separate 1-ns-long laser pulses were used to generate a bright source of 2.96 keV Cl Ly- alpha photons for x-ray scattering, and the spectrum of scattered photons was recorded at a scattering angle of 120 degrees using a highly oriented pyrolytic graphite crystal operated in the von Hamos geometry. A variable delay between the heater and backlighter laser beams measured the scattering time evolution. Comparison with radiation-hydrodynamics simulations shows that the plasma is highly coupled during the first several nanoseconds, then relaxes to a moderate coupling state at later times. Near-elastic scattering amplitudes have been successfully simulated using the screened one-component plasma model. Our main finding is that the near-elastic scattering amplitudes are quite sensitive to the mean ionization state Z[over ] and by extension to the choice of ionization model in the radiation-hydrodynamics simulations used to predict plasma properties within the shocked Li.

  14. Morphological transformations in the magnetite biomineralizing protein Mms6 in iron solutions: A small-angle x-ray scattering study

    DOE PAGES

    Zhang, Honghu; Liu, Xunpei; Feng, Shuren; ...

    2015-02-10

    In this study, magnetotactic bacteria that produce magnetic nanocrystals of uniform size and well-defined morphologies have inspired the use of biomineralization protein Mms6 to promote formation of uniform magnetic nanocrystals in vitro. Small angle X-ray scattering (SAXS) studies in physiological solutions reveal that Mms6 forms compact globular three-dimensional (3D) micelles (approximately 10 nm in diameter) that are, to a large extent, independent of concentration. In the presence of iron ions in the solutions, the general micellar morphology is preserved, however, with associations among micelles that are induced by iron ions. Compared with Mms6, the m2Mms6 mutant (with the sequence ofmore » hydroxyl/carboxyl containing residues in the C-terminal domain shuffled) exhibits subtle morphological changes in the presence of iron ions in solutions. The analysis of the SAXS data is consistent with a hierarchical core–corona micellar structure similar to that found in amphiphilic polymers. The addition of ferric and ferrous iron ions to the protein solution induces morphological changes in the micellar structure by transforming the 3D micelles into objects of reduced dimensionality of 2, with fractal-like characteristics (including Gaussian-chain-like) or, alternatively, platelet-like structures.« less

  15. An x ray scatter approach for non-destructive chemical analysis of low atomic numbered elements

    NASA Technical Reports Server (NTRS)

    Ross, H. Richard

    1993-01-01

    A non-destructive x-ray scatter (XRS) approach has been developed, along with a rapid atomic scatter algorithm for the detection and analysis of low atomic-numbered elements in solids, powders, and liquids. The present method of energy dispersive x-ray fluorescence spectroscopy (EDXRF) makes the analysis of light elements (i.e., less than sodium; less than 11) extremely difficult. Detection and measurement become progressively worse as atomic numbers become smaller, due to a competing process called 'Auger Emission', which reduces fluorescent intensity, coupled with the high mass absorption coefficients exhibited by low energy x-rays, the detection and determination of low atomic-numbered elements by x-ray spectrometry is limited. However, an indirect approach based on the intensity ratio of Compton and Rayleigh scattered has been used to define light element components in alloys, plastics and other materials. This XRS technique provides qualitative and quantitative information about the overall constituents of a variety of samples.

  16. Small angle x ray scattering studies of reverse micelles in supercritical fluids

    NASA Astrophysics Data System (ADS)

    Pfund, D. M.; Fulton, J. L.

    1994-10-01

    The nature of aggregates formed in a supercritical fluid determines its solvent power and selectivity. Small angle X ray scattering (SAXS) is a powerful tool for studying the properties of aggregates with sizes in the 10(angstrom) to 200(angstrom) range. It is also useful in studying those interparticle interactions which operate over a similar distance. The authors have used SAXS to examine the aggregates formed in pure fluids, in mixtures and in fluid/surfactant/water systems. The scattered intensity as a function of angle depends on the geometry, polydispersity, X ray contrast, and interaction strength of the particles as well as on the phase behavior of the system. In this paper the authors present the results of modeling the X-ray scattering from AOT/water reverse micelles in supercritical propane and in propane/carbon dioxide mixtures. They examine the effect of dilution with CO2 anti-solvent on the phase behavior of the system and on the strength of intermicellar attractions. A better understanding of these systems must be obtained before the applications of supercritical reverse micelle systems to extractions, reactions, and enhanced oil recovery can be fully developed.

  17. Theoretical model of x-ray scattering as a dense matter probe.

    PubMed

    Gregori, G; Glenzer, S H; Rozmus, W; Lee, R W; Landen, O L

    2003-02-01

    We present analytical expressions for the dynamic structure factor, or form factor S(k,omega), which is the quantity describing the x-ray cross section from a dense plasma or a simple liquid. Our results, based on the random phase approximation for the treatment on the charged particle coupling, can be applied to describe scattering from either weakly coupled classical plasmas or degenerate electron liquids. Our form factor correctly reproduces the Compton energy down-shift and the known Fermi-Dirac electron velocity distribution for S(k,omega) in the case of a cold degenerate plasma. The usual concept of scattering parameter is also reinterpreted for the degenerate case in order to include the effect of the Thomas-Fermi screening. The results shown in this work can be applied to interpreting x-ray scattering in warm dense plasmas occurring in inertial confinement fusion experiments or for the modeling of solid density matter found in the interior of planets.

  18. Magnetic x-ray scattering studies of holmium using synchro- tron radiation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gibbs, D.; Moncton, D.E.; D'Amico, K.L.

    1985-07-08

    We present the results of magnetic x-ray scattering experiments on the rare-earth metal holmium using synchrotron radiation. Direct high-resolution measurements of the nominally incommensurate magnetic satellite reflections reveal new lock-in behavior which we explain within a simple spin-discommensuration model. As a result of magnetoelastic coupling, the spin-discommensuration array produces additional x-ray diffraction satellites. Their observation further substantiates the model and demonstrates additional advantages of synchrotron radiation for magnetic-structure studies.

  19. Phonon spectroscopy with sub-meV resolution by femtosecond x-ray diffuse scattering

    DOE PAGES

    Zhu, Diling; Robert, Aymeric; Henighan, Tom; ...

    2015-08-10

    We present a reconstruction of the transverse acoustic phonon dispersion of germanium from femtosecond time-resolved x-ray diffuse scattering measurements at the Linac Coherent Light Source. We demonstrate an energy resolution of 0.3 meV with a momentum resolution of 0.01 nm -1 using 10-keV x rays with a bandwidth of ~ 1 eV. This high resolution was achieved simultaneously for a large section of reciprocal space including regions closely following three of the principal symmetry directions. The phonon dispersion was reconstructed with less than 3 h of measurement time, during which neither the x-ray energy, the sample orientation, nor the detectormore » position were scanned. In conclusion, these results demonstrate how time-domain measurements can complement conventional frequency domain inelastic-scattering techniques.« less

  20. Probing the Complex Architecture of Multimodular Carbohydrate-Active Enzymes Using a Combination of Small Angle X-Ray Scattering and X-Ray Crystallography.

    PubMed

    Czjzek, Mirjam; Ficko-Blean, Elizabeth

    2017-01-01

    The various modules in multimodular carbohydrate-active enzymes (CAZymes) may function in catalysis, carbohydrate binding, protein-protein interactions or as linkers. Here, we describe how combining the biophysical techniques of Small Angle X-ray Scattering (SAXS) and macromolecular X-ray crystallography (XRC) provides a powerful tool for examination into questions related to overall structural organization of ultra multimodular CAZymes.

  1. Experimental validation of a multi-energy x-ray adapted scatter separation method

    NASA Astrophysics Data System (ADS)

    Sossin, A.; Rebuffel, V.; Tabary, J.; Létang, J. M.; Freud, N.; Verger, L.

    2016-12-01

    Both in radiography and computed tomography (CT), recently emerged energy-resolved x-ray photon counting detectors enable the identification and quantification of individual materials comprising the inspected object. However, the approaches used for these operations require highly accurate x-ray images. The accuracy of the images is severely compromised by the presence of scattered radiation, which leads to a loss of spatial contrast and, more importantly, a bias in radiographic material imaging and artefacts in CT. The aim of the present study was to experimentally evaluate a recently introduced partial attenuation spectral scatter separation approach (PASSSA) adapted for multi-energy imaging. For this purpose, a prototype x-ray system was used. Several radiographic acquisitions of an anthropomorphic thorax phantom were performed. Reference primary images were obtained via the beam-stop (BS) approach. The attenuation images acquired from PASSSA-corrected data showed a substantial increase in local contrast and internal structure contour visibility when compared to uncorrected images. A substantial reduction of scatter induced bias was also achieved. Quantitatively, the developed method proved to be in relatively good agreement with the BS data. The application of the proposed scatter correction technique lowered the initial normalized root-mean-square error (NRMSE) of 45% between the uncorrected total and the reference primary spectral images by a factor of 9, thus reducing it to around 5%.

  2. Small-angle solution scattering using the mixed-mode pixel array detector.

    PubMed

    Koerner, Lucas J; Gillilan, Richard E; Green, Katherine S; Wang, Suntao; Gruner, Sol M

    2011-03-01

    Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 10(7) 10 keV X-rays, a maximum flux rate of 10(8) X-rays pixel(-1) s(-1), and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements.

  3. Small-angle solution scattering using the mixed-mode pixel array detector

    PubMed Central

    Koerner, Lucas J.; Gillilan, Richard E.; Green, Katherine S.; Wang, Suntao; Gruner, Sol M.

    2011-01-01

    Solution small-angle X-ray scattering (SAXS) measurements were obtained using a 128 × 128 pixel X-ray mixed-mode pixel array detector (MMPAD) with an 860 µs readout time. The MMPAD offers advantages for SAXS experiments: a pixel full-well of >2 × 107 10 keV X-rays, a maximum flux rate of 108 X-rays pixel−1 s−1, and a sub-pixel point-spread function. Data from the MMPAD were quantitatively compared with data from a charge-coupled device (CCD) fiber-optically coupled to a phosphor screen. MMPAD solution SAXS data from lysozyme solutions were of equal or better quality than data captured by the CCD. The read-noise (normalized by pixel area) of the MMPAD was less than that of the CCD by an average factor of 3.0. Short sample-to-detector distances were required owing to the small MMPAD area (19.2 mm × 19.2 mm), and were revealed to be advantageous with respect to detector read-noise. As predicted by the Shannon sampling theory and confirmed by the acquisition of lysozyme solution SAXS curves, the MMPAD at short distances is capable of sufficiently sampling a solution SAXS curve for protein shape analysis. The readout speed of the MMPAD was demonstrated by continuously monitoring lysozyme sample evolution as radiation damage accumulated. These experiments prove that a small suitably configured MMPAD is appropriate for time-resolved solution scattering measurements. PMID:21335900

  4. Solution to the Phase Problem Using Multibeam X-Ray Diffraction.

    NASA Astrophysics Data System (ADS)

    Shen, Qun

    Multi-beam x-ray diffraction, especially the asymmetry effect in the virtual Bragg scattering case, has been proved to provide useful phase information on the structure factors that are involved in the scattering process. A perturbation theory has been developed to provide an analytical expression for the diffracted wave field in virtual Bragg scattering situations, which explains the physical origin of the asymmetry effect. Two experiments on the (202) reflection of benzil, using 3.5 keV x-rays, have shown that the asymmetry effect is visible in a mosaic non-centrosymmetric organic crystal. The results do not depend on the shape of the crystal, hence proving that the method is universally applicable. A practical method to obtain arbitrary values of the phase triplet, based on the perturbation theory, has been developed and shown to work in the case of non-centrosymmetric crystals like benzil.

  5. Kevin Yager on the Nanoscience of Studying Scattered X-Rays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yager, Kevin

    Kevin Yager, a scientist at Brookhaven Lab's Center for Functional Nanomaterials, discusses his research on materials spanning just billionths of a meter. Yager specializes in making new materials through meticulously guided self-assembly and probing nanoscale structures with a technique called x-ray scattering.

  6. Kevin Yager on the Nanoscience of Studying Scattered X-Rays

    ScienceCinema

    Yager, Kevin

    2018-01-16

    Kevin Yager, a scientist at Brookhaven Lab's Center for Functional Nanomaterials, discusses his research on materials spanning just billionths of a meter. Yager specializes in making new materials through meticulously guided self-assembly and probing nanoscale structures with a technique called x-ray scattering.

  7. Small-angle X-ray scattering reveals the solution structure of the full-length DNA gyrase a subunit.

    PubMed

    Costenaro, Lionel; Grossmann, J Günter; Ebel, Christine; Maxwell, Anthony

    2005-02-01

    DNA gyrase is the topoisomerase uniquely able to actively introduce negative supercoils into DNA. Vital in all bacteria, but absent in humans, this enzyme is a successful target for antibacterial drugs. From biophysical experiments in solution, we report the low-resolution structure of the full-length A subunit (GyrA). Analytical ultracentrifugation shows that GyrA is dimeric, but nonglobular. Ab initio modeling from small-angle X-ray scattering allows us to retrieve the molecular envelope of GyrA and thereby the organization of its domains. The available crystallographic structure of the amino-terminal domain (GyrA59) forms a dimeric core, and two additional pear-shaped densities closely flank it in an unexpected position. Each accommodates very well a carboxyl-terminal domain (GyrA-CTD) built from a homologous crystallographic structure. The uniqueness of gyrase is due to the ability of the GyrA-CTDs to wrap DNA. Their position within the GyrA structure strongly suggests a large conformation change of the enzyme upon DNA binding.

  8. Development of In-situ Resonant Soft X-ray Scattering for Soft Materials at Advanced Light Source

    NASA Astrophysics Data System (ADS)

    Wang, Cheng; Hexemer, Alexander; Young, Anthony; Padmore, Howard

    2014-03-01

    Resonant Soft X-ray Scattering was developed at ALS over the past a few years. It combines soft x-ray spectroscopy with x-ray scattering and offers statistical information for 3D chemical morphology over a large sample area. Its unique chemical sensitivity, large accessible size scale, polarization control and high coherence make it a powerful tool for mesoscale chemical/morphological structure characterization for many classes of materials. However, in order to study sciences in naturally occurring conditions, we need to overcome the sample limitations set by the low penetration depth of soft x-rays and requirement of high vacuum. Adapting to the evolving environmental cell designs utilized increasingly in the Electron Microscopy community, we will report our development of customize design liquid/gas environmental cells that will enable soft x-ray scattering experiments on biological, electro-chemical, self-assembly, and hierarchical functional systems in both static and dynamic fashion. Initial RSoXS result of solar fuel membrane assembly/fuel-cell membrane structure in wet cell will be presented.

  9. Simultaneous small- and wide-angle scattering at high X-ray energies.

    PubMed

    Daniels, J E; Pontoni, D; Hoo, Rui Ping; Honkimäki, V

    2010-07-01

    Combined small- and wide-angle X-ray scattering (SAXS/WAXS) is a powerful technique for the study of materials at length scales ranging from atomic/molecular sizes (a few angstroms) to the mesoscopic regime ( approximately 1 nm to approximately 1 microm). A set-up to apply this technique at high X-ray energies (E > 50 keV) has been developed. Hard X-rays permit the execution of at least three classes of investigations that are significantly more difficult to perform at standard X-ray energies (8-20 keV): (i) in situ strain analysis revealing anisotropic strain behaviour both at the atomic (WAXS) as well as at the mesoscopic (SAXS) length scales, (ii) acquisition of WAXS patterns to very large q (>20 A(-1)) thus allowing atomic pair distribution function analysis (SAXS/PDF) of micro- and nano-structured materials, and (iii) utilization of complex sample environments involving thick X-ray windows and/or samples that can be penetrated only by high-energy X-rays. Using the reported set-up a time resolution of approximately two seconds was demonstrated. It is planned to further improve this time resolution in the near future.

  10. Alzheimer's disease imaging biomarkers using small-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Choi, Mina; Alam, Nadia; Dahal, Eshan; Ghammraoui, Bahaa; Badano, Aldo

    2016-03-01

    There is a need for novel imaging techniques for the earlier detection of Alzheimer's disease (AD). Two hallmarks of AD are amyloid beta (Aβ) plaques and tau tangles that are formed in the brain. Well-characterized x-ray cross sections of Aβ and tau proteins in a variety of structural states could potentially be used as AD biomarkers for small-angle x-ray scattering (SAXS) imaging without the need for injectable probes or contrast agents. First, however, the protein structures must be controlled and measured to determine accurate biomarkers for SAXS imaging. Here we report SAXS measurements of Aβ42 and tau352 in a 50% dimethyl sulfoxide (DMSO) solution in which these proteins are believed to remain monomeric because of the stabilizing interaction of DMSO solution. Our SAXS analysis showed the aggregation of both proteins. In particular, we found that the aggregation of Aβ42 slowly progresses with time in comparison to tau352 that aggregates at a faster rate and reaches a steady-state. Furthermore, the measured signals were compared to the theoretical SAXS profiles of Aβ42 monomer, Aβ42 fibril, and tau352 that were computed from their respective protein data bank structures. We have begun the work to systematically control the structural states of these proteins in vitro using various solvent conditions. Our future work is to utilize the distinct SAXS profiles of various structural states of Aβ and tau to build a library of signals of interest for SAXS imaging in brain tissue.

  11. NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering

    DOE PAGES

    Allen, Andrew J.; Zhang, Fan; Kline, R. Joseph; ...

    2017-03-07

    The certification of a new standard reference material for small-angle scattering [NIST Standard Reference Material (SRM) 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering (SAXS)], based on glassy carbon, is presented. Creation of this SRM relies on the intrinsic primary calibration capabilities of the ultra-small-angle X-ray scattering technique. This article describes how the intensity calibration has been achieved and validated in the certified Q range, Q = 0.008–0.25 Å –1, together with the purpose, use and availability of the SRM. The intensity calibration afforded by this robust and stable SRM should be applicable universally to all SAXS instruments thatmore » employ a transmission measurement geometry, working with a wide range of X-ray energies or wavelengths. As a result, the validation of the SRM SAXS intensity calibration using small-angle neutron scattering (SANS) is discussed, together with the prospects for including SANS in a future renewal certification.« less

  12. NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Allen, Andrew J.; Zhang, Fan; Kline, R. Joseph

    The certification of a new standard reference material for small-angle scattering [NIST Standard Reference Material (SRM) 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering (SAXS)], based on glassy carbon, is presented. Creation of this SRM relies on the intrinsic primary calibration capabilities of the ultra-small-angle X-ray scattering technique. This article describes how the intensity calibration has been achieved and validated in the certified Q range, Q = 0.008–0.25 Å –1, together with the purpose, use and availability of the SRM. The intensity calibration afforded by this robust and stable SRM should be applicable universally to all SAXS instruments thatmore » employ a transmission measurement geometry, working with a wide range of X-ray energies or wavelengths. As a result, the validation of the SRM SAXS intensity calibration using small-angle neutron scattering (SANS) is discussed, together with the prospects for including SANS in a future renewal certification.« less

  13. NIST Standard Reference Material 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering.

    PubMed

    Allen, Andrew J; Zhang, Fan; Kline, R Joseph; Guthrie, William F; Ilavsky, Jan

    2017-04-01

    The certification of a new standard reference material for small-angle scattering [NIST Standard Reference Material (SRM) 3600: Absolute Intensity Calibration Standard for Small-Angle X-ray Scattering (SAXS)], based on glassy carbon, is presented. Creation of this SRM relies on the intrinsic primary calibration capabilities of the ultra-small-angle X-ray scattering technique. This article describes how the intensity calibration has been achieved and validated in the certified Q range, Q = 0.008-0.25 Å -1 , together with the purpose, use and availability of the SRM. The intensity calibration afforded by this robust and stable SRM should be applicable universally to all SAXS instruments that employ a transmission measurement geometry, working with a wide range of X-ray energies or wavelengths. The validation of the SRM SAXS intensity calibration using small-angle neutron scattering (SANS) is discussed, together with the prospects for including SANS in a future renewal certification.

  14. Measurements of ionic structure in shock compressed lithium hydride from ultrafast x-ray Thomson scattering.

    PubMed

    Kritcher, A L; Neumayer, P; Brown, C R D; Davis, P; Döppner, T; Falcone, R W; Gericke, D O; Gregori, G; Holst, B; Landen, O L; Lee, H J; Morse, E C; Pelka, A; Redmer, R; Roth, M; Vorberger, J; Wünsch, K; Glenzer, S H

    2009-12-11

    We present the first ultrafast temporally, spectrally, and angularly resolved x-ray scattering measurements from shock-compressed matter. The experimental spectra yield the absolute elastic and inelastic scattering intensities from the measured density of free electrons. Laser-compressed lithium-hydride samples are well characterized by inelastic Compton and plasmon scattering of a K-alpha x-ray probe providing independent measurements of temperature and density. The data show excellent agreement with the total intensity and structure when using the two-species form factor and accounting for the screening of ion-ion interactions.

  15. Accelerated x-ray scatter projection imaging using multiple continuously moving pencil beams

    NASA Astrophysics Data System (ADS)

    Dydula, Christopher; Belev, George; Johns, Paul C.

    2017-03-01

    Coherent x-ray scatter varies with angle and photon energy in a manner dependent on the chemical composition of the scattering material, even for amorphous materials. Therefore, images generated from scattered photons can have much higher contrast than conventional projection radiographs. We are developing a scatter projection imaging prototype at the BioMedical Imaging and Therapy (BMIT) facility of the Canadian Light Source (CLS) synchrotron in Saskatoon, Canada. The best images are obtained using step-and-shoot scanning with a single pencil beam and area detector to capture sequentially the scatter pattern for each primary beam location on the sample. Primary x-ray transmission is recorded simultaneously using photodiodes. The technological challenge is to acquire the scatter data in a reasonable time. Using multiple pencil beams producing partially-overlapping scatter patterns reduces acquisition time but increases complexity due to the need for a disentangling algorithm to extract the data. Continuous sample motion, rather than step-and-shoot, also reduces acquisition time at the expense of introducing motion blur. With a five-beam (33.2 keV, 3.5 mm2 beam area) continuous sample motion configuration, a rectangular array of 12 x 100 pixels with 1 mm sampling width has been acquired in 0.4 minutes (3000 pixels per minute). The acquisition speed is 38 times the speed for single beam step-and-shoot. A system model has been developed to calculate detected scatter patterns given the material composition of the object to be imaged. Our prototype development, image acquisition of a plastic phantom and modelling are described.

  16. X-ray lasers for structural and dynamic biology

    NASA Astrophysics Data System (ADS)

    Spence, J. C. H.; Weierstall, U.; Chapman, H. N.

    2012-10-01

    Research opportunities and techniques are reviewed for the application of hard x-ray pulsed free-electron lasers (XFEL) to structural biology. These include the imaging of protein nanocrystals, single particles such as viruses, pump-probe experiments for time-resolved nanocrystallography, and snapshot wide-angle x-ray scattering (WAXS) from molecules in solution. The use of femtosecond exposure times, rather than freezing of samples, as a means of minimizing radiation damage is shown to open up new opportunities for the molecular imaging of biochemical reactions at room temperature in solution. This is possible using a ‘diffract-and-destroy’ mode in which the incident pulse terminates before radiation damage begins. Methods for delivering hundreds of hydrated bioparticles per second (in random orientations) to a pulsed x-ray beam are described. New data analysis approaches are outlined for the correlated fluctuations in fast WAXS, for protein nanocrystals just a few molecules on a side, and for the continuous x-ray scattering from a single virus. Methods for determining the orientation of a molecule from its diffraction pattern are reviewed. Methods for the preparation of protein nanocrystals are also reviewed. New opportunities for solving the phase problem for XFEL data are outlined. A summary of the latest results is given, which now extend to atomic resolution for nanocrystals. Possibilities for time-resolved chemistry using fast WAXS (solution scattering) from mixtures is reviewed, toward the general goal of making molecular movies of biochemical processes.

  17. Resonant magnetic X-ray scattering studies of heavy fermion superconductors

    NASA Astrophysics Data System (ADS)

    Gaulin, B. D.; Isaacs, E. D.; Lussier, J. G.; Reimers, J. N.; Gibbs, D.; Zschack, P.; Schröder, A.; Taillefer, L.; Garrett, J. D.

    1994-04-01

    The uranium-based heavy fermion superconductors which are known to display weak antiferromagnetism at low temperatures are well suited to study by the newly developed resonant magnetic X-ray scattering technique. We review recent synchrotron X-ray scattering studies of the magnetic behavior of UPd 2Al 3 and URu 2Si 2 and the interaction between magnetism and superconductivity in these materials. These measurements show resolution-limited magnetic Bragg peaks in UPd 2Al 3 in contrast to those in URu 2Si 2. The order parameter as measured at the (0 0 {1}/{2}) magnetic reciprocal lattice position in UPd 2Al 3 is different from that at (0, 0, {3}/{2}), the latter of which indicates a strong anomaly at TNI ∼ 11.8 K below the sharp onset of the antiferromagnetic phase at TN ∼ 14.5 K. Finally, the behavior of the (0 0 {1}/{2}) order parameter is smooth for T ≤ Tc = 2.00 ± 0.04 K.

  18. Tissue Equivalent Phantom Design for Characterization of a Coherent Scatter X-ray Imaging System

    NASA Astrophysics Data System (ADS)

    Albanese, Kathryn Elizabeth

    Scatter in medical imaging is typically cast off as image-related noise that detracts from meaningful diagnosis. It is therefore typically rejected or removed from medical images. However, it has been found that every material, including cancerous tissue, has a unique X-ray coherent scatter signature that can be used to identify the material or tissue. Such scatter-based tissue-identification provides the advantage of locating and identifying particular materials over conventional anatomical imaging through X-ray radiography. A coded aperture X-ray coherent scatter spectral imaging system has been developed in our group to classify different tissue types based on their unique scatter signatures. Previous experiments using our prototype have demonstrated that the depth-resolved coherent scatter spectral imaging system (CACSSI) can discriminate healthy and cancerous tissue present in the path of a non-destructive x-ray beam. A key to the successful optimization of CACSSI as a clinical imaging method is to obtain anatomically accurate phantoms of the human body. This thesis describes the development and fabrication of 3D printed anatomical scatter phantoms of the breast and lung. The purpose of this work is to accurately model different breast geometries using a tissue equivalent phantom, and to classify these tissues in a coherent x-ray scatter imaging system. Tissue-equivalent anatomical phantoms were designed to assess the capability of the CACSSI system to classify different types of breast tissue (adipose, fibroglandular, malignant). These phantoms were 3D printed based on DICOM data obtained from CT scans of prone breasts. The phantoms were tested through comparison of measured scatter signatures with those of adipose and fibroglandular tissue from literature. Tumors in the phantom were modeled using a variety of biological tissue including actual surgically excised benign and malignant tissue specimens. Lung based phantoms have also been printed for future

  19. Fingerprints of orbital physics in magnetic resonant inelastic X-ray scattering

    NASA Astrophysics Data System (ADS)

    Marra, Pasquale

    2012-09-01

    Orbital degrees of freedom play a major role in the physics of many strongly correlated transition metal compounds. However, they are still very difficult to access experimentally, in particular by neutron scattering. We propose here how to reveal orbital occupancies of the system ground state by magnetic resonant inelastic x-ray scattering (RIXS). This is possible because, unlike in neutron scattering, the intensity of the magnetic excitations in RIXS depends essentially on the symmetry of the orbitals where the spins are in.

  20. Supercrystallization of KCl from solution irradiated by soft X-rays

    NASA Astrophysics Data System (ADS)

    Janavičius, A. J.; Rinkūnas, R.; Purlys, R.

    2016-10-01

    The X-rays influence on KCl crystallization in a saturated water solution has been investigated for the aim of comparing it with previously considered NaCl crystallization. The rate of crystallization has been measured in the drying drop in the solution activated by the irradiation. We have measured the influence of the irradiation time of the solution on the rates of KCl crystallization as well as the beginning of the crystallization processes on drying drops. For a longer irradiation time of the solution early crystallization in the drops occurs. A saturated water solution of KCl was irradiated with the diffractometer DRON-3M (Russian device) and this had a great influence on the two-step processes of crystallization. The ionization of the solution by soft X-rays can produce ions, metastable radicals in water, excited crystals' seeds and vacancies in growing crystals by Auger's effect. The X-rays generate a very fast crystallization in the drying drop.

  1. Transmission X-ray scattering as a probe for complex liquid-surface structures

    DOE PAGES

    Fukuto, Masafumi; Yang, Lin; Nykypanchuk, Dmytro; ...

    2016-01-28

    The need for functional materials calls for increasing complexity in self-assembly systems. As a result, the ability to probe both local structure and heterogeneities, such as phase-coexistence and domain morphologies, has become increasingly important to controlling self-assembly processes, including those at liquid surfaces. The traditional X-ray scattering methods for liquid surfaces, such as specular reflectivity and grazing-incidence diffraction, are not well suited to spatially resolving lateral heterogeneities due to large illuminated footprint. A possible alternative approach is to use scanning transmission X-ray scattering to simultaneously probe local intermolecular structures and heterogeneous domain morphologies on liquid surfaces. To test the feasibilitymore » of this approach, transmission small- and wide-angle X-ray scattering (TSAXS/TWAXS) studies of Langmuir films formed on water meniscus against a vertically immersed hydrophilic Si substrate were recently carried out. First-order diffraction rings were observed in TSAXS patterns from a monolayer of hexagonally packed gold nanoparticles and in TWAXS patterns from a monolayer of fluorinated fatty acids, both as a Langmuir monolayer on water meniscus and as a Langmuir–Blodgett monolayer on the substrate. The patterns taken at multiple spots have been analyzed to extract the shape of the meniscus surface and the ordered-monolayer coverage as a function of spot position. These results, together with continual improvement in the brightness and spot size of X-ray beams available at synchrotron facilities, support the possibility of using scanning-probe TSAXS/TWAXS to characterize heterogeneous structures at liquid surfaces.« less

  2. Conformational landscape of a virus by single-particle X-ray scattering

    DOE PAGES

    Hosseinizadeh, Ahmad; Mashayekhi, Ghoncheh; Copperman, Jeremy; ...

    2017-08-14

    Using a manifold-based analysis of experimental diffraction snapshots from an X-ray free electron laser, we determine the three-dimensional structure and conformational landscape of the PR772 virus to a detector-limited resolution of 9 nm. Our results indicate that a single conformational coordinate controls reorganization of the genome, growth of a tubular structure from a portal vertex and release of the genome. Furthermore, these results demonstrate that single-particle X-ray scattering has the potential to shed light on key biological processes.

  3. All-atom ensemble modeling to analyze small angle X-ray scattering of glycosylated proteins

    PubMed Central

    Guttman, Miklos; Weinkam, Patrick; Sali, Andrej; Lee, Kelly K.

    2013-01-01

    Summary The flexible and heterogeneous nature of carbohydrate chains often renders glycoproteins refractory to traditional structure determination methods. Small Angle X-ray scattering (SAXS) can be a useful tool for obtaining structural information of these systems. All-atom modeling of glycoproteins with flexible glycan chains was applied to interpret the solution SAXS data for a set of glycoproteins. For simpler systems (single glycan, with a well defined protein structure), all-atom modeling generates models in excellent agreement with the scattering pattern, and reveals the approximate spatial occupancy of the glycan chain in solution. For more complex systems (several glycan chains, or unknown protein substructure), the approach can still provide insightful models, though the orientations of glycans become poorly determined. Ab initio shape reconstructions appear to capture the global morphology of glycoproteins, but in most cases offer little information about glycan spatial occupancy. The all-atom modeling methodology is available as a webserver at http://modbase.compbio.ucsf.edu/allosmod-foxs. PMID:23473666

  4. A United Effort for Crystal Growth, Neutron Scattering, and X-ray Scattering Studies of Novel Correlated Electron Materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lee, Young S.

    2015-02-12

    The research accomplishments during the award involved experimental studies of correlated electron systems and quantum magnetism. The techniques of crystal growth, neutron scattering, x-ray scattering, and thermodynamic & transport measurements were employed, and graduate students and postdoctoral research associates were trained in these techniques.

  5. Quantifying Nucleic Acid Ensembles with X-ray Scattering Interferometry.

    PubMed

    Shi, Xuesong; Bonilla, Steve; Herschlag, Daniel; Harbury, Pehr

    2015-01-01

    The conformational ensemble of a macromolecule is the complete description of the macromolecule's solution structures and can reveal important aspects of macromolecular folding, recognition, and function. However, most experimental approaches determine an average or predominant structure, or follow transitions between states that each can only be described by an average structure. Ensembles have been extremely difficult to experimentally characterize. We present the unique advantages and capabilities of a new biophysical technique, X-ray scattering interferometry (XSI), for probing and quantifying structural ensembles. XSI measures the interference of scattered waves from two heavy metal probes attached site specifically to a macromolecule. A Fourier transform of the interference pattern gives the fractional abundance of different probe separations directly representing the multiple conformation states populated by the macromolecule. These probe-probe distance distributions can then be used to define the structural ensemble of the macromolecule. XSI provides accurate, calibrated distance in a model-independent fashion with angstrom scale sensitivity in distances. XSI data can be compared in a straightforward manner to atomic coordinates determined experimentally or predicted by molecular dynamics simulations. We describe the conceptual framework for XSI and provide a detailed protocol for carrying out an XSI experiment. © 2015 Elsevier Inc. All rights reserved.

  6. Direct Observation of Cooperative Protein Structural Dynamics of Homodimeric Hemoglobin from 100 ps to 10 ms with Pump-Probe X-ray Solution Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kim, Kyung Hwan; Muniyappan, Srinivasan; Oang, Key Young

    2012-05-29

    Proteins serve as molecular machines in performing their biological functions, but the detailed structural transitions are difficult to observe in their native aqueous environments in real time. For example, despite extensive studies, the solution-phase structures of the intermediates along the allosteric pathways for the transitions between the relaxed (R) and tense (T) forms have been elusive. In this work, we employed picosecond X-ray solution scattering and novel structural analysis to track the details of the structural dynamics of wild-type homodimeric hemoglobin (HbI) from the clam Scapharca inaequivalvis and its F97Y mutant over a wide time range from 100 ps tomore » 56.2 ms. From kinetic analysis of the measured time-resolved X-ray solution scattering data, we identified three structurally distinct intermediates (I 1, I 2, and I 3) and their kinetic pathways common for both the wild type and the mutant. The data revealed that the singly liganded and unliganded forms of each intermediate share the same structure, providing direct evidence that the ligand photolysis of only a single subunit induces the same structural change as the complete photolysis of both subunits does. In addition, by applying novel structural analysis to the scattering data, we elucidated the detailed structural changes in the protein, including changes in the heme-heme distance, the quaternary rotation angle of subunits, and interfacial water gain/loss. The earliest, R-like I 1 intermediate is generated within 100 ps and transforms to the R-like I 2 intermediate with a time constant of 3.2 ± 0.2 ns. Subsequently, the late, T-like I 3 intermediate is formed via subunit rotation, a decrease in the heme-heme distance, and substantial gain of interfacial water and exhibits ligation-dependent formation kinetics with time constants of 730 ± 120 ns for the fully photolyzed form and 5.6 ± 0.8 μs for the partially photolyzed form. For the mutant, the overall kinetics are accelerated, and

  7. T-REX: Thomson-Radiated Extreme X-rays Moving X-Ray Science into the ''Nuclear'' Applications Space with Thompson Scattered Photons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Barty, C P; Hartemann, F V

    2004-09-21

    The scattering of laser photons from relativistic electrons (Thomson scattering) has been demonstrated to be a viable method for the production of ultrashort-duration pulses of tunable radiation in the 10-keV to 100-keV range. Photons in this range are capable of exciting or ionizing even the most tightly bound of atomic electrons. A wide variety of atomistic scale applications are possible. For example, Thomson x-ray sources have been constructed at LLNL (PLEIADES) and LBL as picosecond, stroboscopic probes of atomic-scale dynamics and at Vanderbilt University as element-specific tools for medical radiography and radiology. While these sources have demonstrated an attractive abilitymore » to simultaneously probe on an atomic spatial and temporal scale, they do not necessarily exploit the full potential of the Thomson scattering process to produce high-brightness, high-energy photons. In this white paper, we suggest that the peak brightness of Thomson sources can scale as fast as the 4th power of electron beam energy and that production via Thomson scattering of quasi-monochromatic, tunable radiation in the ''nuclear-range'' between 100-keV and several MeV is potentially a much more attractive application space for this process. Traditional sources in this regime are inherently ultra-broadband and decline rapidly in brightness as a function of photon energy. The output from dedicated, national-laboratory-scale, synchrotron facilities, e.g. APS, SPring8, ESRF etc., declines by more than 10 orders from 100 keV to 1 MeV. At 1 MeV, we conservatively estimate that Thomson-source, peak brightness can exceed that of APS (the best machine in the DOE complex) by more than 15 orders of magnitude. In much the same way that tunable lasers revolutionized atomic spectroscopy, this ''Peta-step'' advance in tunable, narrow-bandwidth, capability should enable entirely new fields of study and new, programmatically-interesting, applications such as: micrometer

  8. Using X-ray Thomson Scattering to Characterize Highly Compressed, Near-Degenerate Plasmas at the NIF

    NASA Astrophysics Data System (ADS)

    Doeppner, Tilo; Kraus, D.; Neumayer, P.; Bachmann, B.; Divol, L.; Kritcher, A. L.; Landen, O. L.; Fletcher, L.; Glenzer, S. H.; Falcone, R. W.; MacDonald, M. J.; Saunders, A.; Witte, B.; Redmer, R.; Chapman, D.; Baggott, R.; Gericke, D. O.; Yi, S. A.

    2017-10-01

    We are developing x-ray Thomson scattering for implosion experiments at the National Ignition Facility to characterize plasma conditions in plastic and beryllium capsules near stagnation, reaching more than 20x compression and electron densities of 1025 cm-3, corresponding to a Fermi energy of 170 eV. Using a zinc He- α x-ray source at 9 keV, experiments at a large scattering angle of 120° measure non-collective scattering spectra with high sensitivity to K-shell ionization, and find higher charge states than predicted by widely used ionization models. Reducing the scattering angle to 30° probes the collective scattering regime with sensitivity to collisions and conductivity. We will discuss recent results and future plans. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344.

  9. Anisotropic x-ray scattering and orientation fields in cardiac tissue cells

    NASA Astrophysics Data System (ADS)

    Bernhardt, M.; Nicolas, J.-D.; Eckermann, M.; Eltzner, B.; Rehfeldt, F.; Salditt, T.

    2017-01-01

    X-ray diffraction from biomolecular assemblies is a powerful technique which can provide structural information about complex architectures such as the locomotor systems underlying muscle contraction. However, in its conventional form, macromolecular diffraction averages over large ensembles. Progress in x-ray optics has now enabled to probe structures on sub-cellular scales, with the beam confined to a distinct organelle. Here, we use scanning small angle x-ray scattering (scanning SAXS) to probe the diffraction from cytoskeleton networks in cardiac tissue cells. In particular, we focus on actin-myosin composites, which we identify as the dominating contribution to the anisotropic diffraction patterns, by correlation with optical fluorescence microscopy. To this end, we use a principal component analysis approach to quantify direction, degree of orientation, nematic order, and the second moment of the scattering distribution in each scan point. We compare the fiber orientation from micrographs of fluorescently labeled actin fibers to the structure orientation of the x-ray dataset and thus correlate signals of two different measurements: the native electron density distribution of the local probing area versus specifically labeled constituents of the sample. Further, we develop a robust and automated fitting approach based on a power law expansion, in order to describe the local structure factor in each scan point over a broad range of the momentum transfer {q}{{r}}. Finally, we demonstrate how the methodology shown for freeze dried cells in the first part of the paper can be translated to alive cell recordings.

  10. A Mo-anode-based in-house source for small-angle X-ray scattering measurements of biological macromolecules

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bruetzel, Linda K.; Fischer, Stefan; Salditt, Annalena

    2016-02-15

    We demonstrate the use of a molybdenum-anode-based in-house small-angle X-ray scattering (SAXS) setup to study biological macromolecules in solution. Our system consists of a microfocus X-ray tube delivering a highly collimated flux of 2.5 × 10{sup 6} photons/s at a beam size of 1.2 × 1.2 mm{sup 2} at the collimation path exit and a maximum beam divergence of 0.16 mrad. The resulting observable scattering vectors q are in the range of 0.38 Å{sup −1} down to 0.009 Å{sup −1} in SAXS configuration and of 0.26 Å{sup −1} up to 5.7 Å{sup −1} in wide-angle X-ray scattering (WAXS) mode. Tomore » determine the capabilities of the instrument, we collected SAXS data on weakly scattering biological macromolecules including proteins and a nucleic acid sample with molecular weights varying from ∼12 to 69 kDa and concentrations of 1.5–24 mg/ml. The measured scattering data display a high signal-to-noise ratio up to q-values of ∼0.2 Å{sup −1} allowing for an accurate structural characterization of the samples. Moreover, the in-house source data are of sufficient quality to perform ab initio 3D structure reconstructions that are in excellent agreement with the available crystallographic structures. In addition, measurements for the detergent decyl-maltoside show that the setup can be used to determine the size, shape, and interactions (as characterized by the second virial coefficient) of detergent micelles. This demonstrates that the use of a Mo-anode based in-house source is sufficient to determine basic geometric parameters and 3D shapes of biomolecules and presents a viable alternative to valuable beam time at third generation synchrotron sources.« less

  11. 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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Szlachetko, J.; Institute of Physics, Jan Kochanowski University, 25-406 Kielce; Nachtegaal, M.

    2012-10-15

    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.

  12. Synchrotron x-ray modification of nanoparticle superlattice formation

    NASA Astrophysics Data System (ADS)

    Lu, Chenguang; Akey, Austin J.; Herman, Irving P.

    2012-09-01

    The synchrotron x-ray radiation used to perform small angle x-ray scattering (SAXS) during the formation of three-dimensional nanoparticle superlattices by drop casting nanoparticle solutions affects the structure and the local crystalline order of the resulting films. The domain size decreases due to the real-time SAXS analysis during drying and more macroscopic changes are visible to the eye.

  13. Determination of plutonium in nitric acid solutions using energy dispersive L X-ray fluorescence with a low power X-ray generator

    NASA Astrophysics Data System (ADS)

    Py, J.; Groetz, J.-E.; Hubinois, J.-C.; Cardona, D.

    2015-04-01

    This work presents the development of an in-line energy dispersive L X-ray fluorescence spectrometer set-up, with a low power X-ray generator and a secondary target, for the determination of plutonium concentration in nitric acid solutions. The intensity of the L X-rays from the internal conversion and gamma rays emitted by the daughter nuclei from plutonium is minimized and corrected, in order to eliminate the interferences with the L X-ray fluorescence spectrum. The matrix effects are then corrected by the Compton peak method. A calibration plot for plutonium solutions within the range 0.1-20 g L-1 is given.

  14. A modified Rayleigh-Gans-Debye formula for small angle X-ray scattering by interstellar dust grains

    NASA Astrophysics Data System (ADS)

    Sharma, Subodh K.

    2015-05-01

    A widely used approximation in studies relating to small angle differential scattering cross-section of X-rays scattered by interstellar dust grains is the well known Rayleigh-Gans-Debye approximation (RGDA). The validity of this approximation, however, is limited only to X-ray energies greater than about 1 keV. At lower energies, this approximation overestimates the exact results. In this paper a modification to the RGDA is suggested. It is shown that a combination of the RGDA with Ramsauer approximation retains the formal simplicity of the RGDA and also yields good agreement with Mie computations at all X-ray energies.

  15. Air-core grid for scattered x-ray rejection

    DOEpatents

    Logan, C.M.; Lane, S.M.

    1995-10-03

    The invention is directed to a grid used in x-ray imaging applications to block scattered radiation while allowing the desired imaging radiation to pass through, and to process for making the grid. The grid is composed of glass containing lead oxide, and eliminates the spacer material used in prior known grids, and is therefore, an air-core grid. The glass is arranged in a pattern so that a large fraction of the area is open allowing the imaging radiation to pass through. A small pore size is used and the grid has a thickness chosen to provide high scatter rejection. For example, the grid may be produced with a 200 {micro}m pore size, 80% open area, and 4 mm thickness. 2 figs.

  16. Air-core grid for scattered x-ray rejection

    DOEpatents

    Logan, Clinton M.; Lane, Stephen M.

    1995-01-01

    The invention is directed to a grid used in x-ray imaging applications to block scattered radiation while allowing the desired imaging radiation to pass through, and to process for making the grid. The grid is composed of glass containing lead oxide, and eliminates the spacer material used in prior known grids, and is therefore, an air-core grid. The glass is arranged in a pattern so that a large fraction of the area is open allowing the imaging radiation to pass through. A small pore size is used and the grid has a thickness chosen to provide high scatter rejection. For example, the grid may be produced with a 200 .mu.m pore size, 80% open area, and 4 mm thickness.

  17. Hybrid deterministic-stochastic modeling of x-ray beam bowtie filter scatter on a CT system.

    PubMed

    Liu, Xin; Hsieh, Jiang

    2015-01-01

    Knowledge of scatter generated by bowtie filter (i.e. x-ray beam compensator) is crucial for providing artifact free images on the CT scanners. Our approach is to use a hybrid deterministic-stochastic simulation to estimate the scatter level generated by a bowtie filter made of a material with low atomic number. First, major components of CT systems, such as source, flat filter, bowtie filter, body phantom, are built into a 3D model. The scattered photon fluence and the primary transmitted photon fluence are simulated by MCNP - a Monte Carlo simulation toolkit. The rejection of scattered photon by the post patient collimator (anti-scatter grid) is simulated with an analytical formula. The biased sinogram is created by superimposing scatter signal generated by the simulation onto the primary x-ray beam signal. Finally, images with artifacts are reconstructed with the biased signal. The effect of anti-scatter grid height on scatter rejection are also discussed and demonstrated.

  18. Fast estimation of first-order scattering in a medical x-ray computed tomography scanner using a ray-tracing technique.

    PubMed

    Liu, Xin

    2014-01-01

    This study describes a deterministic method for simulating the first-order scattering in a medical computed tomography scanner. The method was developed based on a physics model of x-ray photon interactions with matter and a ray tracing technique. The results from simulated scattering were compared to the ones from an actual scattering measurement. Two phantoms with homogeneous and heterogeneous material distributions were used in the scattering simulation and measurement. It was found that the simulated scatter profile was in agreement with the measurement result, with an average difference of 25% or less. Finally, tomographic images with artifacts caused by scatter were corrected based on the simulated scatter profiles. The image quality improved significantly.

  19. Planar small-angle x-ray scattering imaging of phantoms and biological samples

    NASA Astrophysics Data System (ADS)

    Choi, M.; Badano, A.

    2017-04-01

    Coherent small-angle x-ray scattering (SAXS) provides molecular and nanometer-scale structural information. By capturing SAXS data at multiple locations across a sample, we obtained planar images and observed improved contrast given by the difference in the material scattering cross sections. We use phantoms made with 3D printing techniques, with tissue-mimicking plastic (PMMA), and with a highly scattering reference material (AgBe), which were chosen because of their well characterized scattering cross section to demonstrate and characterize the planar imaging of a laboratory SAXS system. We measure 1.07 and 2.14 nm-1 angular intensity maps for AgBe, 9.5 nm-1 for PMMA, and 12.3 nm-1 for Veroclear. The planar SAXS images show material discrimination based on their cross sectional features. The image signal-to-noise ratio (SNR) of each q image was dependent on exposure time and x-ray flux. We observed a lower SNR (91 ± 48) at q angles where no characteristic peaks for either material exist. To improve the visualization of the acquired data by utilizing all q-binned data, we describe a weighted-sum presentation method with a priori knowledge of relevant cross sections to improve the SNR (10 000 ± 6400) over the SNR from a single q-image at 1.07 nm-1 (1100 ± 620). In addition, we describe planar SAXS imaging of a mouse brain slice showing differentiation of tissue types as compared to a conventional absorption-based x-ray imaging technique.

  20. Small-angle X-ray scattering probe of intermolecular interaction in red blood cells

    NASA Astrophysics Data System (ADS)

    Liu, Guan-Fen; Wang, We-Jia; Xu, Jia-Hua; Dong, Yu-Hui

    2015-03-01

    With high concentrations of hemoglobin (Hb) in red blood cells, self-interactions among these molecules could increase the propensities of their polymerization and aggregation. In the present work, high concentration Hb in solution and red blood cells were analyzed by small-angle X-ray scattering. Calculation of the effective structure factor indicates that the interaction of Hb molecules is the same when they are crowded together in both the cell and physiological saline. The Hb molecules stay individual without the formation of aggregates and clusters in cells. Supported by National Basic Research Program of China (2009CB918600) and National Natural Science Foundation of China (10979005)

  1. Precision mechanical structure of an ultra-high-resolution spectrometer for inelastic X-ray scattering instrument

    DOEpatents

    Shu, Deming; Shvydko, Yuri; Stoupin, Stanislav A.; Khachatryan, Ruben; Goetze, Kurt A.; Roberts, Timothy

    2015-04-14

    A method and an ultrahigh-resolution spectrometer including a precision mechanical structure for positioning inelastic X-ray scattering optics are provided. The spectrometer includes an X-ray monochromator and an X-ray analyzer, each including X-ray optics of a collimating (C) crystal, a pair of dispersing (D) element crystals, anomalous transmission filter (F) and a wavelength (W) selector crystal. A respective precision mechanical structure is provided with the X-ray monochromator and the X-ray analyzer. The precision mechanical structure includes a base plate, such as an aluminum base plate; positioning stages for D-crystal alignment; positioning stages with an incline sensor for C/F/W-crystal alignment, and the positioning stages including flexure-based high-stiffness structure.

  2. Soft X-ray production by photon scattering in pulsating binary neutron star sources

    NASA Technical Reports Server (NTRS)

    Bussard, R. W.; Meszaros, P.; Alexander, S.

    1985-01-01

    A new mechanism is proposed as a source of soft (less than 1 keV) radiation in binary pulsating X-ray sources, in the form of photon scattering which leaves the electron in an excited Landau level. In a plasma with parameters typical of such sources, the low-energy X-ray emissivity of this mechanism far exceeds that of bremsstrahlung. This copious source of soft photons is quite adequate to provide the seed photons needed to explain the power-law hard X-ray spectrum by inverse Comptonization on the hot electrons at the base of the accretion column.

  3. Six-dimensional real and reciprocal space small-angle X-ray scattering tomography

    NASA Astrophysics Data System (ADS)

    Schaff, Florian; Bech, Martin; Zaslansky, Paul; Jud, Christoph; Liebi, Marianne; Guizar-Sicairos, Manuel; Pfeiffer, Franz

    2015-11-01

    When used in combination with raster scanning, small-angle X-ray scattering (SAXS) has proven to be a valuable imaging technique of the nanoscale, for example of bone, teeth and brain matter. Although two-dimensional projection imaging has been used to characterize various materials successfully, its three-dimensional extension, SAXS computed tomography, poses substantial challenges, which have yet to be overcome. Previous work using SAXS computed tomography was unable to preserve oriented SAXS signals during reconstruction. Here we present a solution to this problem and obtain a complete SAXS computed tomography, which preserves oriented scattering information. By introducing virtual tomography axes, we take advantage of the two-dimensional SAXS information recorded on an area detector and use it to reconstruct the full three-dimensional scattering distribution in reciprocal space for each voxel of the three-dimensional object in real space. The presented method could be of interest for a combined six-dimensional real and reciprocal space characterization of mesoscopic materials with hierarchically structured features with length scales ranging from a few nanometres to a few millimetres—for example, biomaterials such as bone or teeth, or functional materials such as fuel-cell or battery components.

  4. Six-dimensional real and reciprocal space small-angle X-ray scattering tomography.

    PubMed

    Schaff, Florian; Bech, Martin; Zaslansky, Paul; Jud, Christoph; Liebi, Marianne; Guizar-Sicairos, Manuel; Pfeiffer, Franz

    2015-11-19

    When used in combination with raster scanning, small-angle X-ray scattering (SAXS) has proven to be a valuable imaging technique of the nanoscale, for example of bone, teeth and brain matter. Although two-dimensional projection imaging has been used to characterize various materials successfully, its three-dimensional extension, SAXS computed tomography, poses substantial challenges, which have yet to be overcome. Previous work using SAXS computed tomography was unable to preserve oriented SAXS signals during reconstruction. Here we present a solution to this problem and obtain a complete SAXS computed tomography, which preserves oriented scattering information. By introducing virtual tomography axes, we take advantage of the two-dimensional SAXS information recorded on an area detector and use it to reconstruct the full three-dimensional scattering distribution in reciprocal space for each voxel of the three-dimensional object in real space. The presented method could be of interest for a combined six-dimensional real and reciprocal space characterization of mesoscopic materials with hierarchically structured features with length scales ranging from a few nanometres to a few millimetres--for example, biomaterials such as bone or teeth, or functional materials such as fuel-cell or battery components.

  5. Probing the Interstellar Dust towards the Galactic Centre using X-ray Dust Scattering Halos

    NASA Astrophysics Data System (ADS)

    Jin, C.; Ponti, G.; Haberl, F.; Smith, R.

    2017-10-01

    Dust scattering creates an X-ray halo that contains abundant information about the interstellar dust along the source's line-of-sight (LOS), and is most prominent when the LOS nH is high. In this talk, I will present results from our latest study of a bright dust scattering halo around an eclipsing X-ray binary at 1.45 arcmin away from Sgr A*, namely AX J1745.6-2901. This study is based on a large set of XMM-Newton and Chandra observations, and is so-far the best dust scattering halo study of a X-ray transient in the Galactic centre (GC). I will show that the foreground dust of AX J1745.6-2901 can be decomposed into two major thick dust layers. One layer contains (66-81)% of the total LOS dust and is several kpc away from the source, and so is most likely to reside in the Galactic disc. The other layer is local to the source. I will also show that the dust scattering halo can cause the source spectrum to severely depend on the source extraction region. Such spectral bias can be corrected by our new Xspec model, which is likely to be applicable to Sgr A* and other GC sources as well.

  6. Long Periodic Structure of a Room-Temperature Ionic Liquid by High-Pressure Small-Angle X-Ray Scattering and Wide-Angle X-Ray Scattering: 1-Decyl-3-Methylimidazolium Chloride.

    PubMed

    Abe, Hiroshi; Hamaya, Nozomu; Koyama, Yoshihiro; Kishimura, Hiroaki; Takekiyo, Takahiro; Yoshimura, Yukihiro; Wakabayashi, Daisuke; Funamori, Nobumasa; Matsuishi, Kiyoto

    2018-04-23

    The Bragg reflections of 1-decyl-3-methylimidazolium chloride ([C 10 mim][Cl]), a room-temperature ionic liquid, are observed in a lowly scattered wavevector (q) region using high-pressure (HP) small-angle X-ray scattering methods. The HP crystal of [C 10 mim][Cl] was characterized by an extremely long periodic structure. The peak position at the lowest q (1.4 nm -1 ) was different from that of the prepeak observed in the liquid state (2.3 nm -1 ). Simultaneously, Bragg reflections at high-q were detected using HP wide-angle X-ray scattering. The longest lattice constant was estimated to be 4.3 nm using structural analysis. The crystal structure of HP differed from that of the low-temperature (LT) crystal and the LT liquid crystal. With increasing pressure, Bragg reflections in the high-q component became much broader, and were accompanied by phase transition, although those in the low-q component were observed to be relatively sharp. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. X-ray Intermolecular Structure Factor ( XISF ): separation of intra- and intermolecular interactions from total X-ray scattering data

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mou, Q.; Benmore, C. J.; Yarger, J. L.

    2015-05-09

    XISFis a MATLAB program developed to separate intermolecular structure factors from total X-ray scattering structure factors for molecular liquids and amorphous solids. The program is built on a trust-region-reflective optimization routine with the r.m.s. deviations of atoms physically constrained.XISFhas been optimized for performance and can separate intermolecular structure factors of complex molecules.

  8. Improving small-angle X-ray scattering data for structural analyses of the RNA world

    PubMed Central

    Rambo, Robert P.; Tainer, John A.

    2010-01-01

    Defining the shape, conformation, or assembly state of an RNA in solution often requires multiple investigative tools ranging from nucleotide analog interference mapping to X-ray crystallography. A key addition to this toolbox is small-angle X-ray scattering (SAXS). SAXS provides direct structural information regarding the size, shape, and flexibility of the particle in solution and has proven powerful for analyses of RNA structures with minimal requirements for sample concentration and volumes. In principle, SAXS can provide reliable data on small and large RNA molecules. In practice, SAXS investigations of RNA samples can show inconsistencies that suggest limitations in the SAXS experimental analyses or problems with the samples. Here, we show through investigations on the SAM-I riboswitch, the Group I intron P4-P6 domain, 30S ribosomal subunit from Sulfolobus solfataricus (30S), brome mosaic virus tRNA-like structure (BMV TLS), Thermotoga maritima asd lysine riboswitch, the recombinant tRNAval, and yeast tRNAphe that many problems with SAXS experiments on RNA samples derive from heterogeneity of the folded RNA. Furthermore, we propose and test a general approach to reducing these sample limitations for accurate SAXS analyses of RNA. Together our method and results show that SAXS with synchrotron radiation has great potential to provide accurate RNA shapes, conformations, and assembly states in solution that inform RNA biological functions in fundamental ways. PMID:20106957

  9. Spectral softening in the X-RAY afterglow of GRB 130925A as predicted by the dust scattering model

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhao, Yi-Nan; Shao, Lang, E-mail: lshao@hebtu.edu.cn

    2014-07-01

    Gamma-ray bursts (GRBs) usually occur in a dense star-forming region with a massive circumburst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences and sometimes can dominate the X-ray afterglow. In most of the previous studies, only the Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius of a ≤ 0.1 μm) in the diffuse interstellar medium. When the size of the grains may significantly increase, as in a more dense region where GRBs would occur, the RG approximationmore » may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understand the puzzling X-ray afterglow of recently observed GRB 130925A that showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could well reproduce both the temporal and spectral profile simultaneously. Given the plateau present in the early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.« less

  10. Spectral Softening in the X-Ray Afterglow of GRB 130925A as Predicted by the Dust Scattering Model

    NASA Astrophysics Data System (ADS)

    Zhao, Yi-Nan; Shao, Lang

    2014-07-01

    Gamma-ray bursts (GRBs) usually occur in a dense star-forming region with a massive circumburst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences and sometimes can dominate the X-ray afterglow. In most of the previous studies, only the Rayleigh-Gans (RG) approximation is employed for describing the scattering process, which works accurately for the typical size of grains (with radius of a <= 0.1 μm) in the diffuse interstellar medium. When the size of the grains may significantly increase, as in a more dense region where GRBs would occur, the RG approximation may not be valid enough for modeling detailed observational data. In order to study the temporal and spectral properties of the scattered X-ray emission more accurately with potentially larger dust grains, we provide a practical approach using the series expansions of anomalous diffraction (AD) approximation based on the complicated Mie theory. We apply our calculations to understand the puzzling X-ray afterglow of recently observed GRB 130925A that showed a significant spectral softening. We find that the X-ray scattering scenarios with either AD or RG approximation adopted could well reproduce both the temporal and spectral profile simultaneously. Given the plateau present in the early X-ray light curve, a typical distribution of smaller grains as in the interstellar medium would be suggested for GRB 130925A.

  11. Oligomeric domain structure of human complement factor H by X-ray and neutron solution scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Perkins, S.J.; Nealis, A.S.; Sim, R.B.

    1991-03-19

    Factor H is a regulatory component of the complement system. It has a monomer M{sub r} of 150,000. Primary structure analysis shows that the polypeptide is divided into 20 homologous regions, each 60 amino acid residues long. These are independently folding domains and are termed short consensus repeats (SCRs) or complement control protein (CCP) repeats. High-flux synchrotron x-ray and neutron scatteriing studies were performed in order to define its solution structure in conditions close to physiological. The M{sub r} of factor H was determined as 250,000-320,000 to show that factor H is dimeric. The radius of gyration R{sub G} ofmore » native factor H by X-rays or by neutrons in 0% or 100% {sup 2}H{sub 2}O buffers is not measurable but is greater than 12.5 nm. Two cross-sectional radii of gyration R{sub XS-1} and R{sub XS-2} were determined as 3.0-3.1 and 1.8 nm, respectively. Analyses of the cross-sectional intensities show that factor H is composed of two distinct subunits. This model corresponds to an actual R{sub G} fo 21-23 nm. The separation between each SCR/CCP in factor H is close to 4 nm. In the solution structure of factor H, the SCR/CCP domains are in a highly extended conformation.« less

  12. XUV and x-ray elastic scattering of attosecond electromagnetic pulses on atoms

    NASA Astrophysics Data System (ADS)

    Rosmej, F. B.; Astapenko, V. A.; Lisitsa, V. S.

    2017-12-01

    Elastic scattering of electromagnetic pulses on atoms in XUV and soft x-ray ranges is considered for ultra-short pulses. The inclusion of the retardation term, non-dipole interaction and an efficient scattering tensor approximation allowed studying the scattering probability in dependence of the pulse duration for different carrier frequencies. Numerical calculations carried out for Mg, Al and Fe atoms demonstrate that the scattering probability is a highly nonlinear function of the pulse duration and has extrema for pulse carrier frequencies in the vicinity of the resonance-like features of the polarization charge spectrum. Closed expressions for the non-dipole correction and the angular dependence of the scattered radiation are obtained.

  13. Measuring and modeling diffuse scattering in protein X-ray crystallography

    PubMed Central

    Van Benschoten, Andrew H.; Liu, Lin; Gonzalez, Ana; Brewster, Aaron S.; Sauter, Nicholas K.; Wall, Michael E.

    2016-01-01

    X-ray diffraction has the potential to provide rich information about the structural dynamics of macromolecules. To realize this potential, both Bragg scattering, which is currently used to derive macromolecular structures, and diffuse scattering, which reports on correlations in charge density variations, must be measured. Until now, measurement of diffuse scattering from protein crystals has been scarce because of the extra effort of collecting diffuse data. Here, we present 3D measurements of diffuse intensity collected from crystals of the enzymes cyclophilin A and trypsin. The measurements were obtained from the same X-ray diffraction images as the Bragg data, using best practices for standard data collection. To model the underlying dynamics in a practical way that could be used during structure refinement, we tested translation–libration–screw (TLS), liquid-like motions (LLM), and coarse-grained normal-modes (NM) models of protein motions. The LLM model provides a global picture of motions and was refined against the diffuse data, whereas the TLS and NM models provide more detailed and distinct descriptions of atom displacements, and only used information from the Bragg data. Whereas different TLS groupings yielded similar Bragg intensities, they yielded different diffuse intensities, none of which agreed well with the data. In contrast, both the LLM and NM models agreed substantially with the diffuse data. These results demonstrate a realistic path to increase the number of diffuse datasets available to the wider biosciences community and indicate that dynamics-inspired NM structural models can simultaneously agree with both Bragg and diffuse scattering. PMID:27035972

  14. Measuring and modeling diffuse scattering in protein X-ray crystallography

    DOE PAGES

    Van Benschoten, Andrew H.; Liu, Lin; Gonzalez, Ana; ...

    2016-03-28

    X-ray diffraction has the potential to provide rich information about the structural dynamics of macromolecules. To realize this potential, both Bragg scattering, which is currently used to derive macromolecular structures, and diffuse scattering, which reports on correlations in charge density variations, must be measured. Until now, measurement of diffuse scattering from protein crystals has been scarce because of the extra effort of collecting diffuse data. Here, we present 3D measurements of diffuse intensity collected from crystals of the enzymes cyclophilin A and trypsin. The measurements were obtained from the same X-ray diffraction images as the Bragg data, using best practicesmore » for standard data collection. To model the underlying dynamics in a practical way that could be used during structure refinement, we tested translation–libration–screw (TLS), liquid-like motions (LLM), and coarse-grained normal-modes (NM) models of protein motions. The LLM model provides a global picture of motions and was refined against the diffuse data, whereas the TLS and NM models provide more detailed and distinct descriptions of atom displacements, and only used information from the Bragg data. Whereas different TLS groupings yielded similar Bragg intensities, they yielded different diffuse intensities, none of which agreed well with the data. In contrast, both the LLM and NM models agreed substantially with the diffuse data. In conclusion, these results demonstrate a realistic path to increase the number of diffuse datasets available to the wider biosciences community and indicate that dynamics-inspired NM structural models can simultaneously agree with both Bragg and diffuse scattering.« less

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

    PubMed

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

    2013-07-01

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

  16. X-ray Intermolecular Structure Factor (XISF): separation of intra- and intermolecular interactions from total X-ray scattering data

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mou, Q.; Benmore, C. J.; Yarger, J. L.

    2015-06-01

    XISF is a MATLAB program developed to separate intermolecular structure factors from total X-ray scattering structure factors for molecular liquids and amorphous solids. The program is built on a trust-region-reflective optimization routine with the r.m.s. deviations of atoms physically constrained. XISF has been optimized for performance and can separate intermolecular structure factors of complex molecules.

  17. Small-angle scattering of polychromatic X-rays: effects of bandwidth, spectral shape and high harmonics.

    PubMed

    Chen, Sen; Luo, Sheng Nian

    2018-03-01

    Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10-100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are explored via Gaussian and half-Gaussian spectra. Synchrotron undulator spectra represented by two undulator sources of the Advanced Photon Source are examined as an example, as regards the influence of asymmetric harmonic shape, fundamental harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.

  18. Small-angle scattering of polychromatic X-rays: effects of bandwidth, spectral shape and high harmonics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Sen; Luo, Sheng-Nian

    Polychromatic X-ray sources can be useful for photon-starved small-angle X-ray scattering given their high spectral fluxes. Their bandwidths, however, are 10–100 times larger than those using monochromators. To explore the feasibility, ideal scattering curves of homogeneous spherical particles for polychromatic X-rays are calculated and analyzed using the Guinier approach, maximum entropy and regularization methods. Monodisperse and polydisperse systems are explored. The influence of bandwidth and asymmetric spectra shape are exploredviaGaussian and half-Gaussian spectra. Synchrotron undulator spectra represented by two undulator sources of the Advanced Photon Source are examined as an example, as regards the influence of asymmetric harmonic shape, fundamentalmore » harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.« less

  19. Development study of the X-ray scattering properties of a group of optically polished flat samples

    NASA Technical Reports Server (NTRS)

    Froechtenigt, J. F.

    1973-01-01

    A group of twelve optically polished flat samples were used to study the scattering of X-rays. The X-ray beam reflected from the twelve optical flat samples was analyzed by means of a long vacuum system of special design for these tests. The scattering measurements were made at 8.34A and 0.92 deg angle of incidence. The results for ten of the samples are comparable, the two exceptions being the fire polished samples.

  20. High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

    DOE PAGES

    Fletcher, L. B.; Zastrau, U.; Galtier, E.; ...

    2016-08-15

    Here, we present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen andmore » focused on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].« less

  1. High resolution x-ray Thomson scattering measurements from cryogenic hydrogen jets using the linac coherent light source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Fletcher, L. B., E-mail: lbfletch@slac.stanford.edu; Galtier, E.; Gamboa, E. J.

    2016-11-15

    We present the first spectrally resolved measurements of x-rays scattered from cryogenic hydrogen jets in the single photon counting limit. The 120 Hz capabilities of the LCLS, together with a novel hydrogen jet design [J. B. Kim et al., Rev. Sci. Instrum. (these proceedings)], allow for the ability to record a near background free spectrum. Such high-dynamic-range x-ray scattering measurements enable a platform to study ultra-fast, laser-driven, heating dynamics of hydrogen plasmas. This measurement has been achieved using two highly annealed pyrolytic graphite crystal spectrometers to spectrally resolve 5.5 keV x-rays elastically and inelastically scattered from cryogenic hydrogen and focusedmore » on Cornell-SLAC pixel array detectors [S. Herrmann et al., Nucl. Instrum. Methods Phys. Res., Sect. A 718, 550 (2013)].« less

  2. The accurate assessment of small-angle X-ray scattering data

    DOE PAGES

    Grant, Thomas D.; Luft, Joseph R.; Carter, Lester G.; ...

    2015-01-23

    Small-angle X-ray scattering (SAXS) has grown in popularity in recent times with the advent of bright synchrotron X-ray sources, powerful computational resources and algorithms enabling the calculation of increasingly complex models. However, the lack of standardized data-quality metrics presents difficulties for the growing user community in accurately assessing the quality of experimental SAXS data. Here, a series of metrics to quantitatively describe SAXS data in an objective manner using statistical evaluations are defined. These metrics are applied to identify the effects of radiation damage, concentration dependence and interparticle interactions on SAXS data from a set of 27 previously described targetsmore » for which high-resolution structures have been determined via X-ray crystallography or nuclear magnetic resonance (NMR) spectroscopy. Studies show that these metrics are sufficient to characterize SAXS data quality on a small sample set with statistical rigor and sensitivity similar to or better than manual analysis. The development of data-quality analysis strategies such as these initial efforts is needed to enable the accurate and unbiased assessment of SAXS data quality.« less

  3. The dust scattering halo of Cygnus X-3

    NASA Astrophysics Data System (ADS)

    Corrales, L. R.; Paerels, F.

    2015-10-01

    Dust grains scatter X-ray light through small angles, producing a diffuse halo image around bright X-ray point sources situated behind a large amount of interstellar material. We present analytic solutions to the integral for the dust scattering intensity, which allow for a Bayesian analysis of the scattering halo around Cygnus X-3. Fitting the optically thin 4-6 keV halo surface brightness profile yields the dust grain size and spatial distribution. We assume a power-law distribution of grain sizes (n ∝ a-p) and fit for p, the grain radius cut-off amax, and dust mass column. We find that a p ≈ 3.5 dust grain size distribution with amax ≈ 0.2 μm fits the halo profile relatively well, whether the dust is distributed uniformly along the line of sight or in clumps. We find that a model consisting of two dust screens, representative of foreground spiral arms, requires the foreground Perseus arm to contain 80 per cent of the total dust mass. The remaining 20 per cent of the dust, which may be associated with the outer spiral arm of the Milky Way, is located within 1 kpc of Cyg X-3. Regardless of which model was used, we found τ_sca ˜ 2 E_keV^{-2}. We examine the energy resolved haloes of Cyg X-3 from 1 to 6 keV and find that there is a sharp drop in scattering halo intensity when E < 2-3 keV, which cannot be explained with multiple scattering effects. We hypothesize that this may be caused by large dust grains or material with unique dielectric properties, causing the scattering cross-section to depart from the Rayleigh-Gans approximation that is used most often in X-ray scattering studies. The foreground Cyg OB2 association, which contains several evolved stars with large extinction values, is a likely culprit for grains of unique size or composition.

  4. Use of a solar panel as a directionally sensitive large-area radiation monitor for direct and scattered x-rays and gamma-rays.

    PubMed

    Abdul-Majid, S

    1987-01-01

    The characteristics of a 25.4 X 91 cm solar cell panel used as an x-ray and gamma-ray radiation monitor are presented. Applications for monitoring the primary x-ray beam are described at different values of operating currents and voltages as well as for directional dependence of scattered radiation. Other applications in gamma-ray radiography are also given. The detector showed linear response to both x-ray and gamma-ray exposures. The equipment is rigid, easy to use, relatively inexpensive and requires no power supply or any complex electronic equipment.

  5. An Optimized Table-Top Small-Angle X-ray Scattering Set-up for the Nanoscale Structural Analysis of Soft Matter

    NASA Astrophysics Data System (ADS)

    Sibillano, T.; de Caro, L.; Altamura, D.; Siliqi, D.; Ramella, M.; Boccafoschi, F.; Ciasca, G.; Campi, G.; Tirinato, L.; di Fabrizio, E.; Giannini, C.

    2014-11-01

    The paper shows how a table top superbright microfocus laboratory X-ray source and an innovative restoring-data algorithm, used in combination, allow to analyze the super molecular structure of soft matter by means of Small Angle X-ray Scattering ex-situ experiments. The proposed theoretical approach is aimed to restore diffraction features from SAXS profiles collected from low scattering biomaterials or soft tissues, and therefore to deal with extremely noisy diffraction SAXS profiles/maps. As biological test cases we inspected: i) residues of exosomes' drops from healthy epithelial colon cell line and colorectal cancer cells; ii) collagen/human elastin artificial scaffolds developed for vascular tissue engineering applications; iii) apoferritin protein in solution. Our results show how this combination can provide morphological/structural nanoscale information to characterize new artificial biomaterials and/or to get insight into the transition between healthy and pathological tissues during the progression of a disease, or to morphologically characterize nanoscale proteins, based on SAXS data collected in a room-sized laboratory.

  6. Small-Angle X-ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles

    DTIC Science & Technology

    2016-12-01

    Intercalibration of small-angle X- Ray and neutron-scattering data. Journal of Applied Crystallography . 1988;21:629–638. 7. Zhang F, Ilavsky J, Long GG...Materials Transactions A. 2009;41:1151–1158. 8. Kusz J, Bohm H. Performance of a confocal multilayer X-ray optic. Journal of Applied Crystallography ...Journal of Applied Crystallography . 2004;37:369–380. 10. Orthaber D, Bergmann A, Glatter O. SAXS experiments on absolute scale with Kratky systems using

  7. Small Angle X ray Scattering (SAXS) Instrument Performance and Validation Using Silver Nanoparticles

    DTIC Science & Technology

    2016-12-01

    Intercalibration of small-angle X- Ray and neutron-scattering data. Journal of Applied Crystallography . 1988;21:629–638. 7. Zhang F, Ilavsky J, Long GG...Materials Transactions A. 2009;41:1151–1158. 8. Kusz J, Bohm H. Performance of a confocal multilayer X-ray optic. Journal of Applied Crystallography ...Journal of Applied Crystallography . 2004;37:369–380. 10. Orthaber D, Bergmann A, Glatter O. SAXS experiments on absolute scale with Kratky systems using

  8. Pinhole-type two-dimensional ultra-small-angle X-ray scattering on the micrometer scale

    PubMed Central

    Kishimoto, Hiroyuki; Shinohara, Yuya; Suzuki, Yoshio; Takeuchi, Akihisa; Yagi, Naoto; Amemiya, Yoshiyuki

    2014-01-01

    A pinhole-type two-dimensional ultra-small-angle X-ray scattering set-up at a so-called medium-length beamline at SPring-8 is reported. A long sample-to-detector distance, 160.5 m, can be used at this beamline and a small-angle resolution of 0.25 µm−1 was thereby achieved at an X-ray energy of 8 keV. PMID:24365910

  9. Compact X-ray sources: X-rays from self-reflection

    NASA Astrophysics Data System (ADS)

    Mangles, Stuart P. D.

    2012-05-01

    Laser-based particle acceleration offers a way to reduce the size of hard-X-ray sources. Scientists have now developed a simple scheme that produces a bright flash of hard X-rays by using a single laser pulse both to generate and to scatter an electron beam.

  10. Structure and collective dynamics of hydrated anti-freeze protein type III from 180 K to 298 K by X-ray diffraction and inelastic X-ray scattering

    NASA Astrophysics Data System (ADS)

    Yoshida, Koji; Baron, Alfred Q. R.; Uchiyama, Hiroshi; Tsutsui, Satoshi; Yamaguchi, Toshio

    2016-04-01

    We investigated hydrated antifreeze protein type III (AFP III) powder with a hydration level h (=mass of water/mass of protein) of 0.4 in the temperature range between 180 K and 298 K using X-ray diffraction and inelastic X-ray scattering (IXS). The X-ray diffraction data showed smooth, largely monotonic changes between 180 K and 298 K without freezing water. Meanwhile, the collective dynamics observed by IXS showed a strong change in the sound velocity at 180 K, after being largely temperature independent at higher temperatures (298-220 K). We interpret this change in terms of the dynamic transition previously discussed using other probes including THz IR absorption spectroscopy and incoherent elastic and quasi-elastic neutron scattering. This finding suggests that the dynamic transition of hydrated proteins is observable on the subpicosecond time scale as well as nano- and pico-second scales, both in collective dynamics from IXS and single particle dynamics from neutron scattering. Moreover, it is most likely that the dynamic transition of hydrated AFP III is not directly correlated with its hydration structure.

  11. Structure and collective dynamics of hydrated anti-freeze protein type III from 180 K to 298 K by X-ray diffraction and inelastic X-ray scattering.

    PubMed

    Yoshida, Koji; Baron, Alfred Q R; Uchiyama, Hiroshi; Tsutsui, Satoshi; Yamaguchi, Toshio

    2016-04-07

    We investigated hydrated antifreeze protein type III (AFP III) powder with a hydration level h (=mass of water/mass of protein) of 0.4 in the temperature range between 180 K and 298 K using X-ray diffraction and inelastic X-ray scattering (IXS). The X-ray diffraction data showed smooth, largely monotonic changes between 180 K and 298 K without freezing water. Meanwhile, the collective dynamics observed by IXS showed a strong change in the sound velocity at 180 K, after being largely temperature independent at higher temperatures (298-220 K). We interpret this change in terms of the dynamic transition previously discussed using other probes including THz IR absorption spectroscopy and incoherent elastic and quasi-elastic neutron scattering. This finding suggests that the dynamic transition of hydrated proteins is observable on the subpicosecond time scale as well as nano- and pico-second scales, both in collective dynamics from IXS and single particle dynamics from neutron scattering. Moreover, it is most likely that the dynamic transition of hydrated AFP III is not directly correlated with its hydration structure.

  12. Ultrafast Kα x-ray Thomson scattering from shock compressed lithium hydride

    DOE PAGES

    Kritcher, A. L.; Neumayer, P.; Castor, J.; ...

    2009-04-13

    Spectrally and temporally resolved x-ray Thomson scattering using ultrafast Ti Kα x rays has provided experimental validation for modeling of the compression and heating of shocked matter. The coalescence of two shocks launched into a solid density LiH target by a shaped 6 ns heater beam was observed from rapid heating to temperatures of 2.2 eV, enabling tests of shock timing models. Here, the temperature evolution of the target at various times during shock progression was characterized from the intensity of the elastic scattering component. The observation of scattering from plasmons, electron plasma oscillations, at shock coalescence indicates a transitionmore » to a dense metallic plasma state in LiH. From the frequency shift of the measured plasmon feature the electron density was directly determined with high accuracy, providing a material compression of a factor of 3 times solid density. The quality of data achieved in these experiments demonstrates the capability for single shot dynamic characterization of dense shock compressed matter. Here, the conditions probed in this experiment are relevant for the study of the physics of planetary formation and to characterize inertial confinement fusion targets for experiments such as on the National Ignition Facility, Lawrence Livermore National Laboratory.« less

  13. Thermal management and prototype testing of Compton scattering X-ray beam position monitor for the Advanced Photon Source Upgrade

    NASA Astrophysics Data System (ADS)

    Lee, S. H.; Yang, B. X.; Collins, J. T.; Ramanathan, M.

    2017-02-01

    Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source Upgrade. In the next-generation XBPMs for the canted-undulator front ends, where two undulator beams are separated by 1.0 mrad, the lower beam power (<10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from a diamond placed edge-on to the x-ray beam. Because of the high peak power density of the x-ray beams, this diamond experiences high temperatures and has to be clamped to a water-cooled heat spreader using thermal interface materials (TIMs), which play a key role in reducing the temperature of the diamond. To evaluate temperature changes through the interface via thermal simulations, the thermal contact resistance (TCR) of TIMs at an interface between two solid materials under even contact pressure must be known. This paper addresses the TCR measurements of several TIMs, including gold, silver, pyrolytic graphite sheet, and 3D graphene foam. In addition, a prototype of a Compton-scattering XBPM with diamond blades was installed at APS Beamline 24-ID-A in May 2015 and has been tested. This paper presents the design of the Compton-scattering XBPM, and compares thermal simulation results obtained for the diamond blade of this XBPM by the finite element method with in situ empirical measurements obtained by using reliable infrared technology.

  14. Thermal management and prototype testing of Compton scattering X-ray beam position monitor for the Advanced Photon Source Upgrade

    DOE PAGES

    Lee, S. H.; Yang, B. X.; Collins, J. T.; ...

    2017-02-07

    Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source Upgrade. In the next-generation XBPMs for the canted-undulator front ends, where two undulator beams are separated by 1.0 mrad, the lower beam power (<10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from a diamond placed edge-on to the x-ray beam. Because of the high peak power density of the x-ray beams, this diamond experiences high temperatures and has to be clamped to a water-cooled heat spreader using thermal interface materials (TIMs),more » which play a key role in reducing the temperature of the diamond. To evaluate temperature changes through the interface via thermal simulations, the thermal contact resistance (TCR) of TIMs at an interface between two solid materials under even contact pressure must be known. This paper addresses the TCR measurements of several TIMs, including gold, silver, pyrolytic graphite sheet, and 3D graphene foam. In addition, a prototype of a Compton-scattering XBPM with diamond blades was installed at APS Beamline 24-ID-A in May 2015 and has been tested. This study presents the design of the Compton-scattering XBPM, and compares thermal simulation results obtained for the diamond blade of this XBPM by the finite element method with in situ empirical measurements obtained by using reliable infrared technology.« less

  15. Thermal management and prototype testing of Compton scattering X-ray beam position monitor for the Advanced Photon Source Upgrade.

    PubMed

    Lee, S H; Yang, B X; Collins, J T; Ramanathan, M

    2017-02-01

    Accurate and stable x-ray beam position monitors (XBPMs) are key elements in obtaining the desired user beam stability in the Advanced Photon Source Upgrade. In the next-generation XBPMs for the canted-undulator front ends, where two undulator beams are separated by 1.0 mrad, the lower beam power (<10 kW) per undulator allows us to explore lower-cost solutions based on Compton scattering from a diamond placed edge-on to the x-ray beam. Because of the high peak power density of the x-ray beams, this diamond experiences high temperatures and has to be clamped to a water-cooled heat spreader using thermal interface materials (TIMs), which play a key role in reducing the temperature of the diamond. To evaluate temperature changes through the interface via thermal simulations, the thermal contact resistance (TCR) of TIMs at an interface between two solid materials under even contact pressure must be known. This paper addresses the TCR measurements of several TIMs, including gold, silver, pyrolytic graphite sheet, and 3D graphene foam. In addition, a prototype of a Compton-scattering XBPM with diamond blades was installed at APS Beamline 24-ID-A in May 2015 and has been tested. This paper presents the design of the Compton-scattering XBPM, and compares thermal simulation results obtained for the diamond blade of this XBPM by the finite element method with in situ empirical measurements obtained by using reliable infrared technology.

  16. Interpretation of solution scattering data from lipid nanodiscs

    DOE PAGES

    Graziano, Vito; Miller, Lisa; Yang, Lin

    2018-02-01

    The structural information contained in solution scattering data from empty lipid nanodiscs is examined in the context of a multi-component geometric model. X-ray scattering data were collected on nanodiscs of different compositions at scattering vector magnitudes up to 2.0 Å −1 . Through the calculation of the partial form factor for each of the nanodisc components before the isotropic average, structural parameters in the model were correlated to the features observed in the X-ray scattering data and to the corresponding distance distribution function. It is shown that, in general, the features at ∼0.3–0.6 Å −1 in the scattering data correlate to themore » bilayer structure. The data also support the argument that the elliptical shape of nanodiscs found in model fitting is physical, rather than an artefact due to the nanodisc size distribution. The lipid chain packing peak at ∼1.5 Å −1 is visible in the data and reflects the lipid bilayer phase transition. The shape change in the distance distribution function across the phase transition suggests that the nanodiscs are more circular in the fluid phase. The implication of these findings for model fitting of empty and protein-loaded nanodiscs is discussed.« less

  17. Generation of bright attosecond x-ray pulse trains via Thomson scattering from laser-plasma accelerators.

    PubMed

    Luo, W; Yu, T P; Chen, M; Song, Y M; Zhu, Z C; Ma, Y Y; Zhuo, H B

    2014-12-29

    Generation of attosecond x-ray pulse attracts more and more attention within the advanced light source user community due to its potentially wide applications. Here we propose an all-optical scheme to generate bright, attosecond hard x-ray pulse trains by Thomson backscattering of similarly structured electron beams produced in a vacuum channel by a tightly focused laser pulse. Design parameters for a proof-of-concept experiment are presented and demonstrated by using a particle-in-cell code and a four-dimensional laser-Compton scattering simulation code to model both the laser-based electron acceleration and Thomson scattering processes. Trains of 200 attosecond duration hard x-ray pulses holding stable longitudinal spacing with photon energies approaching 50 keV and maximum achievable peak brightness up to 1020 photons/s/mm2/mrad2/0.1%BW for each micro-bunch are observed. The suggested physical scheme for attosecond x-ray pulse trains generation may directly access the fastest time scales relevant to electron dynamics in atoms, molecules and materials.

  18. Monitoring the recrystallisation of amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering.

    PubMed

    Palomäki, Emmi; Ahvenainen, Patrik; Ehlers, Henrik; Svedström, Kirsi; Huotari, Simo; Yliruusi, Jouko

    2016-07-11

    In this paper we present a fast model system for monitoring the recrystallization of quench-cooled amorphous xylitol using Raman spectroscopy and wide-angle X-ray scattering. The use of these two methods enables comparison between surface and bulk crystallization. Non-ordered mesoporous silica micro-particles were added to the system in order to alter the rate of crystallization of the amorphous xylitol. Raman measurements showed that adding silica to the system increased the rate of surface crystallization, while X-ray measurements showed that the rate of bulk crystallization decreased. Using this model system it is possible to measure fast changes, which occur in minutes or within a few hours. Raman-spectroscopy and wide-angle X-ray scattering were found to be complementary techniques when assessing surface and bulk crystallization of amorphous xylitol. Copyright © 2016 Elsevier B.V. All rights reserved.

  19. Synthesis of nanoparticles through x-ray radiolysis using synchrotron radiation

    NASA Astrophysics Data System (ADS)

    Yamaguchi, A.; Okada, I.; Fukuoka, T.; Ishihara, M.; Sakurai, I.; Utsumi, Y.

    2016-09-01

    The synthesis and deposition of nanoparticles consisting of Cu and Au in a CuSO4 solution with some kinds of alcohol and electroplating solution containing gold (I) trisodium disulphite under synchrotron X-ray radiation was investigated. The functional group of alcohol plays an important in nucleation, growth and aggregation process of copper and cupric oxide particles. We found that the laboratory X-ray source also enables us to synthesize the NPs from the metallic solution. As increasing X-ray exposure time, the full length at half width of particle size distribution is broader and higher-order nanostructure containing NPs clusters is formed. The surface-enhanced Raman scattering (SERS) of 4, 4'-bipyridine (4bpy) in aqueous solution was measured using higher-order nanostructure immobilized on silicon substrates under systematically-varied X-ray exposure. This demonstration provide a clue to develop a three-dimensional printing and sensor for environmental analyses and molecular detection through simple SERS measurements.

  20. Optimized Detector Angular Configuration Increases the Sensitivity of X-ray Fluorescence Computed Tomography (XFCT).

    PubMed

    Ahmad, Moiz; Bazalova-Carter, Magdalena; Fahrig, Rebecca; Xing, Lei

    2015-05-01

    In this work, we demonstrated that an optimized detector angular configuration based on the anisotropic energy distribution of background scattered X-rays improves X-ray fluorescence computed tomography (XFCT) detection sensitivity. We built an XFCT imaging system composed of a bench-top fluoroscopy X-ray source, a CdTe X-ray detector, and a phantom motion stage. We imaged a 6.4-cm-diameter phantom containing different concentrations of gold solution and investigated the effect of detector angular configuration on XFCT image quality. Based on our previous theoretical study, three detector angles were considered. The X-ray fluorescence detector was first placed at 145 (°) (approximating back-scatter) to minimize scatter X-rays. XFCT image quality was compared to images acquired with the detector at 60 (°) (forward-scatter) and 90 (°) (side-scatter). The datasets for the three different detector positions were also combined to approximate an isotropically arranged detector. The sensitivity was optimized with detector in the 145 (°) back-scatter configuration counting the 78-keV gold Kβ1 X-rays. The improvement arose from the reduced energy of scattered X-ray at the 145 (°) position and the large energy separation from gold K β1 X-rays. The lowest detected concentration in this configuration was 2.5 mgAu/mL (or 0.25% Au with SNR = 4.3). This concentration could not be detected with the 60 (°) , 90 (°) , or isotropic configurations (SNRs = 1.3, 0, 2.3, respectively). XFCT imaging dose of 14 mGy was in the range of typical clinical X-ray CT imaging doses. To our knowledge, the sensitivity achieved in this experiment is the highest in any XFCT experiment using an ordinary bench-top X-ray source in a phantom larger than a mouse ( > 3 cm).

  1. Scatter fractions from linear accelerators with x-ray energies from 6 to 24 MV.

    PubMed

    Taylor, P L; Rodgers, J E; Shobe, J

    1999-08-01

    Computation of shielding requirements for a linear accelerator must take into account the amount of radiation scattered from the patient to areas outside the primary beam. Currently, the most frequently used data are from NCRP 49 that only includes data for x-ray energies up to 6 MV and angles from 30 degrees to 135 degrees. In this work we have determined by Monte Carlo simulation the scattered fractions of dose for a wide range of energies and angles of clinical significance including 6, 10, 18, and 24 MV and scattering angles from 10 degrees to 150 degrees. Calculations were made for a 400 cm2 circular field size impinging onto a spherical phantom. Scattered fractions of dose were determined at 1 m from the phantom. Angles from 10 degrees to 30 degrees are of concern for higher energies where the scatter is primarily in the forward direction. An error in scatter fraction may result in too little secondary shielding near the junction with the primary barrier. The Monte Carlo code ITS (Version 3.0) developed at Sandia National Laboratory and NIST was used to simulate scatter from the patient to the barrier. Of significance was the variation of calculated scattered dose with depth of measurement within the barrier indicating that accurate values may be difficult to obtain. Mean energies of scatter x-ray spectra are presented.

  2. Laboratory and In-Flight In-Situ X-ray Imaging and Scattering Facility for Materials, Biotechnology and Life Sciences

    NASA Technical Reports Server (NTRS)

    2003-01-01

    We propose a multifunctional X-ray facility for the Materials, Biotechnology and Life Sciences Programs to visualize formation and behavior dynamics of materials, biomaterials, and living organisms, tissues and cells. The facility will combine X-ray topography, phase micro-imaging and scattering capabilities with sample units installed on the goniometer. This should allow, for the first time, to monitor under well defined conditions, in situ, in real time: creation of imperfections during growth of semiconductors, metal, dielectric and biomacromolecular crystals and films, high-precision diffraction from crystals within a wide range of temperatures and vapor, melt, solution conditions, internal morphology and changes in living organisms, tissues and cells, diffraction on biominerals, nanotubes and particles, radiation damage, also under controlled formation/life conditions. The system will include an ultrabright X-ray source, X-ray mirror, monochromator, image-recording unit, detectors, and multipurpose diffractometer that fully accommodate and integrate furnaces and samples with other experimental environments. The easily adjustable laboratory and flight versions will allow monitoring processes under terrestrial and microgravity conditions. The flight version can be made available using a microsource combined with multilayer or capillary optics.

  3. X-ray Echo Spectroscopy

    NASA Astrophysics Data System (ADS)

    Shvyd'ko, Yuri

    2016-02-01

    X-ray echo spectroscopy, a counterpart of neutron spin echo, is being introduced here to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a pointlike x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-0.02 meV ultrahigh-resolution IXS applications (resolving power >108 ) with broadband ≃5 - 13 meV dispersing systems are introduced featuring more than 103 signal enhancement. The technique is general, applicable in different photon frequency domains.

  4. Synchrotron-based coherent scatter x-ray projection imaging using an array of monoenergetic pencil beams.

    PubMed

    Landheer, Karl; Johns, Paul C

    2012-09-01

    Traditional projection x-ray imaging utilizes only the information from the primary photons. Low-angle coherent scatter images can be acquired simultaneous to the primary images and provide additional information. In medical applications scatter imaging can improve x-ray contrast or reduce dose using information that is currently discarded in radiological images to augment the transmitted radiation information. Other applications include non-destructive testing and security. A system at the Canadian Light Source synchrotron was configured which utilizes multiple pencil beams (up to five) to create both primary and coherent scatter projection images, simultaneously. The sample was scanned through the beams using an automated step-and-shoot setup. Pixels were acquired in a hexagonal lattice to maximize packing efficiency. The typical pitch was between 1.0 and 1.6 mm. A Maximum Likelihood-Expectation Maximization-based iterative method was used to disentangle the overlapping information from the flat panel digital x-ray detector. The pixel value of the coherent scatter image was generated by integrating the radial profile (scatter intensity versus scattering angle) over an angular range. Different angular ranges maximize the contrast between different materials of interest. A five-beam primary and scatter image set (which had a pixel beam time of 990 ms and total scan time of 56 min) of a porcine phantom is included. For comparison a single-beam coherent scatter image of the same phantom is included. The muscle-fat contrast was 0.10 ± 0.01 and 1.16 ± 0.03 for the five-beam primary and scatter images, respectively. The air kerma was measured free in air using aluminum oxide optically stimulated luminescent dosimeters. The total area-averaged air kerma for the scan was measured to be 7.2 ± 0.4 cGy although due to difficulties in small-beam dosimetry this number could be inaccurate.

  5. A novel method for resonant inelastic soft X-ray scattering via photoelectron spectroscopy detection

    DOE PAGES

    Dakovski, Georgi L.; Lin, Ming-Fu; Damiani, Daniel S.; ...

    2017-10-05

    A method for measuring resonant inelastic X-ray scattering based on the conversion of X-ray photons into photoelectrons is presented in this paper. The setup is compact, relies on commercially available detectors, and offers significant flexibility. Finally, this method is demonstrated at the Linac Coherent Light Source with ~0.5 eV resolution at the cobalt L 3-edge, with signal rates comparable with traditional grating spectrometers.

  6. X-Ray Polarization from High Mass X-Ray Binaries

    NASA Technical Reports Server (NTRS)

    Kallman, T.; Dorodnitsyn, A.; Blondin, J.

    2015-01-01

    X-ray astronomy allows study of objects which may be associated with compact objects, i.e. neutron stars or black holes, and also may contain strong magnetic fields. Such objects are categorically non-spherical, and likely non-circular when projected on the sky. Polarization allows study of such geometric effects, and X-ray polarimetry is likely to become feasible for a significant number of sources in the future. A class of potential targets for future X-ray polarization observations is the high mass X-ray binaries (HMXBs), which consist of a compact object in orbit with an early type star. In this paper we show that X-ray polarization from HMXBs has a distinct signature which depends on the source inclination and orbital phase. The presence of the X-ray source displaced from the star creates linear polarization even if the primary wind is spherically symmetric whenever the system is viewed away from conjunction. Direct X-rays dilute this polarization whenever the X-ray source is not eclipsed; at mid-eclipse the net polarization is expected to be small or zero if the wind is circularly symmetric around the line of centers. Resonance line scattering increases the scattering fraction, often by large factors, over the energy band spanned by resonance lines. Real winds are not expected to be spherically symmetric, or circularly symmetric around the line of centers, owing to the combined effects of the compact object gravity and ionization on the wind hydrodynamics. A sample calculation shows that this creates polarization fractions ranging up to tens of percent at mid-eclipse.

  7. Vesicle Adhesion and Fusion Studied by Small-Angle X-Ray Scattering.

    PubMed

    Komorowski, Karlo; Salditt, Annalena; Xu, Yihui; Yavuz, Halenur; Brennich, Martha; Jahn, Reinhard; Salditt, Tim

    2018-04-24

    We have studied the adhesion state (also denoted by docking state) of lipid vesicles as induced by the divalent ions Ca 2+ or Mg 2+ at well-controlled ion concentration, lipid composition, and charge density. The bilayer structure and the interbilayer distance in the docking state were analyzed by small-angle x-ray scattering. A strong adhesion state was observed for DOPC:DOPS vesicles, indicating like-charge attraction resulting from ion correlations. The observed interbilayer separations of ∼1.6 nm agree quantitatively with the predictions of electrostatics in the strong coupling regime. Although this phenomenon was observed when mixing anionic and zwitterionic (or neutral) lipids, pure anionic membranes (DOPS) with highest charge density σ resulted in a direct phase transition to a multilamellar state, which must be accompanied by rupture and fusion of vesicles. To extend the structural assay toward protein-controlled docking and fusion, we have characterized reconstituted N-ethylmaleimide-sensitive factor attachment protein receptors in controlled proteoliposome suspensions by small-angle x-ray scattering. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  8. Dewetting of thin polymer films: an X-ray scattering study

    NASA Astrophysics Data System (ADS)

    Müller-Buschbaum, P.; Stamm, M.

    1998-06-01

    The surface morphology of different dewetting states of thin polymer films (polystyrene) on top of silicon substrates was investigated. With diffuse X-ray scattering in the region of total external reflection a high in-plane resolution was achieved. We observe a new nano-dewetting structure which coexists with the well known mesoscopic dewetting structures of holes, cellular pattern and drops. This nano-dewetting structure consists of small dimples with a diameter in the nanometer range. It results from the dewetting of a remaining ultra-thin polymer layer and can be explained with theoretical predictions of spinodal decomposition. The experimental results of the scattering study are confirmed with scanning-force microscopy measurements.

  9. High duty cycle inverse Compton scattering X-ray source

    DOE PAGES

    Ovodenko, A.; Agustsson, R.; Babzien, M.; ...

    2016-12-22

    Inverse Compton Scattering (ICS) is an emerging compact X-ray source technology, where the small source size and high spectral brightness are of interest for multitude of applications. However, to satisfy the practical flux requirements, a high-repetition-rate ICS system needs to be developed. To this end, this article reports the experimental demonstration of a high peak brightness ICS source operating in a burst mode at 40 MHz. A pulse train interaction has been achieved by recirculating a picosecond CO 2 laser pulse inside an active optical cavity synchronized to the electron beam. The pulse train ICS performance has been characterized atmore » 5- and 15- pulses per train and compared to a single pulse operation under the same operating conditions. Lastly, with the observed near-linear X-ray photon yield gain due to recirculation, as well as noticeably higher operational reliability, the burst-mode ICS offers a great potential for practical scalability towards high duty cycles.« less

  10. Using acoustic levitation in synchrotron based laser pump hard x-ray probe experiments

    NASA Astrophysics Data System (ADS)

    Hu, Bin; Lerch, Jason; Suthar, Kamlesh; Dichiara, Anthony

    Acoustic levitation provides a platform to trap and hold a small amount of material by using standing pressure waves without a container. The technique has a potential to be used for laser pump x-ray probe experiments; x-ray scattering and laser distortion from the container can be avoided, sample consumption can be minimized, and unwanted chemistry that may occur at the container interface can be avoided. The method has been used at synchrotron sources for studying protein and pharmaceutical solutions using x-ray diffraction (XRD) and small angle x-ray scattering (SAXS). However, pump-probe experiments require homogeneously excited samples, smaller than the absorption depth of the material that must be held stably at the intersection of both the laser and x-ray beams. We discuss 1) the role of oscillations in acoustic levitation and the optimal acoustic trapping conditions for x-ray/laser experiments, 2) opportunities to automate acoustic levitation for fast sample loading and manipulation, and 3) our experimental results using SAXS to monitor laser induced thermal expansion in gold nanoparticles solution. We also performed Finite Element Analysis to optimize the trapping performance and stability of droplets ranging from 0.4 mm to 2 mm. Our early x-ray/laser demonstrated the potential of the technique for time-resolved X-ray science.

  11. X-ray data booklet. Revision

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vaughan, D.

    A compilation of data is presented. Included are properties of the elements, electron binding energies, characteristic x-ray energies, fluorescence yields for K and L shells, Auger energies, energy levels for hydrogen-, helium-, and neonlike ions, scattering factors and mass absorption coefficients, and transmission bands of selected filters. Also included are selected reprints on scattering processes, x-ray sources, optics, x-ray detectors, and synchrotron radiation facilities. (WRF)

  12. A model of primary and scattered photon fluence for mammographic x-ray image quantification

    NASA Astrophysics Data System (ADS)

    Tromans, Christopher E.; Cocker, Mary R.; Brady, Michael, Sir

    2012-10-01

    We present an efficient method to calculate the primary and scattered x-ray photon fluence component of a mammographic image. This can be used for a range of clinically important purposes, including estimation of breast density, personalized image display, and quantitative mammogram analysis. The method is based on models of: the x-ray tube; the digital detector; and a novel ray tracer which models the diverging beam emanating from the focal spot. The tube model includes consideration of the anode heel effect, and empirical corrections for wear and manufacturing tolerances. The detector model is empirical, being based on a family of transfer functions that cover the range of beam qualities and compressed breast thicknesses which are encountered clinically. The scatter estimation utilizes optimal information sampling and interpolation (to yield a clinical usable computation time) of scatter calculated using fundamental physics relations. A scatter kernel arising around each primary ray is calculated, and these are summed by superposition to form the scatter image. Beam quality, spatial position in the field (in particular that arising at the air-boundary due to the depletion of scatter contribution from the surroundings), and the possible presence of a grid, are considered, as is tissue composition using an iterative refinement procedure. We present numerous validation results that use a purpose designed tissue equivalent step wedge phantom. The average differences between actual acquisitions and modelled pixel intensities observed across the adipose to fibroglandular attenuation range vary between 5% and 7%, depending on beam quality and, for a single beam quality are 2.09% and 3.36% respectively with and without a grid.

  13. LIGHT SCATTERING PROPERTIES OF GLIADIN AFTER X-RAY IRRADIATION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, J.

    1962-01-01

    The gliadin portion of wheat gluten prepared in 60% ethanol solution was investigated for its light scattering properties after x irradiation. Results show that the effect of irradiation depends on the quality of the sample, such as dry or wet. The average molecular weight of liadin decreased in accordance with the time of irradiation. The longer the irradiated time, the more SH groups were setfree. (P.C.H.)

  14. Scatter correction for x-ray conebeam CT using one-dimensional primary modulation

    NASA Astrophysics Data System (ADS)

    Zhu, Lei; Gao, Hewei; Bennett, N. Robert; Xing, Lei; Fahrig, Rebecca

    2009-02-01

    Recently, we developed an efficient scatter correction method for x-ray imaging using primary modulation. A two-dimensional (2D) primary modulator with spatially variant attenuating materials is inserted between the x-ray source and the object to separate primary and scatter signals in the Fourier domain. Due to the high modulation frequency in both directions, the 2D primary modulator has a strong scatter correction capability for objects with arbitrary geometries. However, signal processing on the modulated projection data requires knowledge of the modulator position and attenuation. In practical systems, mainly due to system gantry vibration, beam hardening effects and the ramp-filtering in the reconstruction, the insertion of the 2D primary modulator results in artifacts such as rings in the CT images, if no post-processing is applied. In this work, we eliminate the source of artifacts in the primary modulation method by using a one-dimensional (1D) modulator. The modulator is aligned parallel to the ramp-filtering direction to avoid error magnification, while sufficient primary modulation is still achieved for scatter correction on a quasicylindrical object, such as a human body. The scatter correction algorithm is also greatly simplified for the convenience and stability in practical implementations. The method is evaluated on a clinical CBCT system using the Catphan© 600 phantom. The result shows effective scatter suppression without introducing additional artifacts. In the selected regions of interest, the reconstruction error is reduced from 187.2HU to 10.0HU if the proposed method is used.

  15. Effects of the environmental factors on the casein micelle structure studied by cryo transmission electron microscopy and small-angle x-ray scattering/ultrasmall-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Marchin, Stéphane; Putaux, Jean-Luc; Pignon, Frédéric; Léonil, Joëlle

    2007-01-01

    Casein micelles are colloidal protein-calcium-transport complexes whose structure has not been unequivocally elucidated. This study used small-angle x-ray scattering (SAXS) and ultrasmall angle x-ray scattering (USAXS) as well as cryo transmission electron microscopy (cryo-TEM) to provide fine structural details on their structure. Cryo-TEM observations of native casein micelles fractionated by differential centrifugation showed that colloidal calcium phosphate appeared as nanoclusters with a diameter of about 2.5nm. They were uniformly distributed in a homogeneous tangled web of caseins and were primarily responsible for the intensity distribution in the SAXS profiles at the highest q vectors corresponding to the internal structure of the casein micelles. A specific demineralization of casein micelles by decreasing the pH from 6.7 to 5.2 resulted in a reduced granular aspect of the micelles observed by cryo-TEM and the existence of a characteristic point of inflection in SAXS profiles. This supports the hypothesis that the smaller substructures detected by SAXS are colloidal calcium phosphate nanoclusters rather than putative submicelles.

  16. Measurement and Interpretation of Diffuse Scattering in X-Ray Diffraction for Macromolecular Crystallography

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wall, Michael E.

    X-ray diffraction from macromolecular crystals includes both sharply peaked Bragg reflections and diffuse intensity between the peaks. The information in Bragg scattering reflects the mean electron density in the unit cells of the crystal. The diffuse scattering arises from correlations in the variations of electron density that may occur from one unit cell to another, and therefore contains information about collective motions in proteins.

  17. Soft x-ray speckle from rough surfaces

    NASA Astrophysics Data System (ADS)

    Porter, Matthew Stanton

    Dynamic light scattering has been of great use in determining diffusion times for polymer solutions. At the same time, polymer thin films are becoming of increasing importance, especially in the semiconductor industry where they are used as photoresists and interlevel dielectrics. As the dimensions of these devices decrease we will reach a point where lasers will no longer be able to probe the length scales of interest. Current laser wavelengths limit the size of observable diffusion lengths to 180-700 nm. This dissertation will discuss attempts at pushing dynamic fight scattering experiments into the soft x-ray region so that we can examine fluctuations in polymer thin films on the molecular length scale. The dissertation explores the possibility of carrying out a dynamic light scattering experiment in the soft x-ray regime. A detailed account of how to meet the basic requirements for a coherent scattering experiment in the soft x-ray regime win be given. In addition, a complete description of the chamber design will be discussed. We used our custom designed scattering chamber to collect reproducible coherent soft x-ray scattering data from etched silicon wafers and from polystyrene coated silicon wafers. The data from the silicon wafers followed the statistics for a well-developed speckle pattern while the data from the polystyrene films exhibited Poisson statistics. We used the data from both the etched wafers and the polystyrene coated wafers to place a lower limit of ~20 Å on the RMS surface roughness of samples which will produce well defined speckle patterns for the current detector setup. Future experiments which use the criteria set forth in this dissertation have the opportunity to be even more successful than this dissertation project.

  18. Luminescent properties under X-ray excitation of Ba(1-x)PbxWO4 disordered solid solution

    NASA Astrophysics Data System (ADS)

    Bakiz, B.; Hallaoui, A.; Taoufyq, A.; Benlhachemi, A.; Guinneton, F.; Villain, S.; Ezahri, M.; Valmalette, J.-C.; Arab, M.; Gavarri, J.-R.

    2018-02-01

    A series of polycrystalline barium-lead tungstate Ba1-xPbxWO4 with 0 ≤ x ≤ 1 was synthesized using a classical solid-state method with thermal treatment at 1000 °C. These materials were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier Transform Raman (FT-Raman) spectroscopy. X-ray diffraction profile analyses were performed using Rietveld method. These materials crystallized in the scheelite tetragonal structure and behaved as quasi ideal solid solution. Raman spectroscopy confirmed the formation of the solid solution. Structural distortions were evidenced in X-ray diffraction profiles and in vibration Raman spectra. The scanning electron microscopy experiments showed large and rounded irregular grains. Luminescence experiments were performed under X-ray excitation. The luminescence emission profiles have been interpreted in terms of four Gaussian components, with a major contribution of blue emission. The integrated intensity of luminescence reached a maximum value in the composition range x = 0.3-0.6, in relation with distortions of crystal lattice.

  19. Verwey transition in a magnetite ultrathin film by resonant x-ray scattering

    NASA Astrophysics Data System (ADS)

    Grenier, S.; Bailly, A.; Ramos, A. Y.; De Santis, M.; Joly, Y.; Lorenzo, J. E.; Garaudée, S.; Frericks, M.; Arnaud, S.; Blanc, N.; Boudet, N.

    2018-03-01

    We report a detailed study of the Verwey transition in a magnetite ultrathin film (UTF) grown on Ag(001) using resonant x-ray scattering (RXS). RXS was measured at the Fe K-edge on the crystal truncation rod of the substrate, increasing the sensitivity to the film thanks to the cross-interference, thereby obtaining an x-ray phase-shift reference and a polarization analyzer. The spectra were interpreted with ad hoc calculations based on density functional theory within a surface-scattering formalism. We observed that the UTF has a relatively sharp transition temperature TV=120 K and is remarkably close to the bulk temperature for such thickness. We determined the specific Fe stacking at the interface with the substrate below TV, and detected a spectroscopic signal evolving with temperature from TV up to at least TV+80 K, hinting that the RT crystallographic structure does not set at TV in the UTF.

  20. Small Angle X-Ray Scattering Study of Meso-Tetrakis (4-Sulfonatophenyl) Porphyrin in Aqueous Solution: A Self-Aggregation Model

    PubMed Central

    Gandini, S.C.M.; Gelamo, E.L.; Itri, R.; Tabak, M.

    2003-01-01

    The aggregate morphology of meso-tetrakis(4-sulfonatophenyl) porphyrin (TPPS4) in aqueous solution is investigated by using small angle x-ray scattering (SAXS) technique. Measurements were performed at pH 4.0 and 9.0 to monitor the pH influence on the structural parameters of the aggregates. Radii of gyration were obtained from distance distribution functions p(r) analysis. The experimental data of TPPS4 at pH 4.0 showed well-defined oscillations characteristic of large aggregates in contrast to the SAXS curve of 5 mM TPPS4 at pH 9.0, where both a significant decrease in the intensity and the disappearance of the oscillation peaks suggest the dissociation of the aggregate. A 340-Å long “hollow” cylinder with shell thickness of 20 Å, compatible to the porphyrin molecule dimension, represents well the scattering curve of the aggregates at pH 4.0. According to the fitting parameters, 26 porphyrin molecules self-associate into a ringlike configuration in the plane of the cylinder cross-section. The total number of porphyrin molecules in the whole aggregate was also estimated as ∼3000. The model compatible to SAXS data of a hollow cylinder with J-aggregation in the cross-section and H-aggregation (columnar stacking) between the cylinder layers is consistent with optical absorption spectroscopic data both in the literature and obtained in this work. PMID:12885669

  1. A radially accessible tubular in situ X-ray cell for spatially resolved operando scattering and spectroscopic studies of electrochemical energy storage devices

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Hao; Allan, Phoebe K.; Borkiewicz, Olaf J.

    2016-09-16

    A tubularoperandoelectrochemical cell has been developed to allow spatially resolved X-ray scattering and spectroscopic measurements of individual cell components, or regions thereof, during device operation. These measurements are enabled by the tubular cell geometry, wherein the X-ray-transparent tube walls allow radial access for the incident and scattered/transmitted X-ray beam; by probing different depths within the electrode stack, the transformation of different components or regions can be resolved. The cell is compatible with a variety of synchrotron-based scattering, absorption and imaging methodologies. The reliability of the electrochemical cell and the quality of the resulting X-ray scattering and spectroscopic data are demonstratedmore » for two types of energy storage: the evolution of the distribution of the state of charge of an Li-ion battery electrode during cycling is documented using X-ray powder diffraction, and the redistribution of ions between two porous carbon electrodes in an electrochemical double-layer capacitor is documented using X-ray absorption near-edge spectroscopy.« less

  2. Structure and collective dynamics of hydrated anti-freeze protein type III from 180 K to 298 K by X-ray diffraction and inelastic X-ray scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yoshida, Koji; Baron, Alfred Q. R.; Uchiyama, Hiroshi

    We investigated hydrated antifreeze protein type III (AFP III) powder with a hydration level h (=mass of water/mass of protein) of 0.4 in the temperature range between 180 K and 298 K using X-ray diffraction and inelastic X-ray scattering (IXS). The X-ray diffraction data showed smooth, largely monotonic changes between 180 K and 298 K without freezing water. Meanwhile, the collective dynamics observed by IXS showed a strong change in the sound velocity at 180 K, after being largely temperature independent at higher temperatures (298–220 K). We interpret this change in terms of the dynamic transition previously discussed using othermore » probes including THz IR absorption spectroscopy and incoherent elastic and quasi-elastic neutron scattering. This finding suggests that the dynamic transition of hydrated proteins is observable on the subpicosecond time scale as well as nano- and pico-second scales, both in collective dynamics from IXS and single particle dynamics from neutron scattering. Moreover, it is most likely that the dynamic transition of hydrated AFP III is not directly correlated with its hydration structure.« less

  3. Tunable X-ray source

    DOEpatents

    Boyce, James R [Williamsburg, VA

    2011-02-08

    A method for the production of X-ray bunches tunable in both time and energy level by generating multiple photon, X-ray, beams through the use of Thomson scattering. The method of the present invention simultaneously produces two X-ray pulses that are tunable in energy and/or time.

  4. Alamethicin in lipid bilayers: combined use of X-ray scattering and MD simulations.

    PubMed

    Pan, Jianjun; Tieleman, D Peter; Nagle, John F; Kucerka, Norbert; Tristram-Nagle, Stephanie

    2009-06-01

    We study fully hydrated bilayers of two di-monounsaturated phospholipids diC18:1PC (DOPC) and diC22:1PC with varying amounts of alamethicin (Alm). We combine the use of X-ray diffuse scattering and molecular dynamics simulations to determine the orientation of alamethicin in model lipids. Comparison of the experimental and simulated form factors shows that Alm helices are inserted transmembrane at high humidity and high concentrations, in agreement with earlier results. The X-ray scattering data and the MD simulations agree that membrane thickness changes very little up to 1/10 Alm/DOPC. In contrast, the X-ray data indicate that the thicker diC22:1PC membrane thins with added Alm, a total decrease in thickness of 4 A at 1/10 Alm/diC22:1PC. The different effect of Alm on the thickness changes of the two bilayers is consistent with Alm having a hydrophobic thickness close to the hydrophobic thickness of 27 A for DOPC; Alm is then mismatched with the 7 A thicker diC22:1PC bilayer. The X-ray data indicate that Alm decreases the bending modulus (K(C)) by a factor of approximately 2 in DOPC and a factor of approximately 10 in diC22:1PC membranes (P/L approximately 1/10). The van der Waals and fluctuational interactions between bilayers are also evaluated through determination of the anisotropic B compressibility modulus.

  5. Diffuse x-ray scattering and transmission electron microscopy study of defects in antimony-implanted silicon

    NASA Astrophysics Data System (ADS)

    Takamura, Y.; Marshall, A. F.; Mehta, A.; Arthur, J.; Griffin, P. B.; Plummer, J. D.; Patel, J. R.

    2004-04-01

    Ion implantation followed by laser annealing has been used to create supersaturated and electrically active concentrations of antimony in silicon. Upon subsequent thermal annealing, however, these metastable dopants deactivate towards the equilibrium solubility limit. In this work, the formation of inactive antimony structures has been studied with grazing incidence diffuse x-ray scattering, and transmission electron microscopy, and the results are correlated to previous high-resolution x-ray diffraction data. We find that at a concentration of 6.0×1020 cm-3, small, incoherent clusters of radius 3-4 Å form during annealing at 900 °C. At a higher concentration of 2.2×1021 cm-3, deactivation at 600 °C occurs through the formation of small, antimony aggregates and antimony precipitates. The size of these precipitates from diffuse x-ray scattering is roughly 15 Å in radius for anneal times from 15 to 180 seconds. This value is consistent with the features observed in high-resolution and mass contrast transmission electron microscopy images. The coherent nature of the aggregates and precipitates causes the expansion of the surrounding silicon matrix as the deactivation progresses. In addition, the sensitivity of the diffuse x-ray scattering technique has allowed us to detect the presence of small clusters of radius ˜2 Å in unprocessed Czochralski silicon wafers. These defects are not observed in floating zone silicon wafers, and are tentatively attributed to thermal donors.

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

    PubMed Central

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

    2013-01-01

    X-ray absorption and scattering spectroscopies involving the 3d transition-metal K- and L-edges have a long history in studying inorganic and bioinorganic molecules. However, there have been very few studies using the M-edges, which are below 100 eV. Synchrotron-based X-ray sources can have higher energy resolution at M-edges. M-edge X-ray absorption spectroscopy (XAS) and resonant inelastic X-ray scattering (RIXS) could therefore provide complementary information to K- and L-edge spectroscopies. In this study, M 2,3-edge XAS on several Co, Ni and Cu complexes are measured and their spectral information, such as chemical shifts and covalency effects, are analyzed and discussed. In addition, M 2,3-edge RIXS on NiO, NiF2 and two other covalent complexes have been performed and different d–d transition patterns have been observed. Although still preliminary, this work on 3d metal complexes demonstrates the potential to use M-edge XAS and RIXS on more complicated 3d metal complexes in the future. The potential for using high-sensitivity and high-resolution superconducting tunnel junction X-ray detectors below 100 eV is also illustrated and discussed. PMID:23765304

  7. Measurement of illite particle thickness using a direct Fourier transform of small-angle X-ray scattering data

    USGS Publications Warehouse

    Shang, Chao; Rice, James A.; Eberl, Dennis D.; Lin, Jar-Shyong

    2003-01-01

    It has been suggested that interstratified illite-smectite (I-S) minerals are composed of aggregates of fundamental particles. Many attempts have been made to measure the thickness of such fundamental particles, but each of the methods used suffers from its own limitations and uncertainties. Small-angle X-ray scattering (SAXS) can be used to measure the thickness of particles that scatter X-rays coherently. We used SAXS to study suspensions of Na-rectorite and other illites with varying proportions of smectite. The scattering intensity (I) was recorded as a function of the scattering vector, q = (4 /) sin(/2), where  is the X-ray wavelength and  is the scattering angle. The experimental data were treated with a direct Fourier transform to obtain the pair distance distribution function (PDDF) that was then used to determine the thickness of illite particles. The Guinier and Porod extrapolations were used to obtain the scattering intensity beyond the experimental q, and the effects of such extrapolations on the PDDF were examined. The thickness of independent rectorite particles (used as a reference mineral) is 18.3 Å. The SAXS results are compared with those obtained by X-ray diffraction peak broadening methods. It was found that the power-law exponent (α) obtained by fitting the data in the region of q = 0.1-0.6 nm-1 to the power law (I = I0q-α) is a linear function of illite particle thickness. Therefore, illite particle thickness could be predicted by the linear relationship as long as the thickness is within the limit where α <4.0.

  8. Optical surface evaluation by soft X-ray scattering

    NASA Technical Reports Server (NTRS)

    Green, James C.; Finley, David S.; Bowyer, Stuart; Malina, Roger F.

    1986-01-01

    During the fabrication of the mirrors for the Extreme Ultraviolet Explorer (EUVE), methods for evaluating the surface quality of the optics have been developed. Measurement of soft X-ray scattering profiles allows for the determination of the surface roughness and correlation lengths for highly polished metal surfaces. With this method, the surface parameters for one of the Wolter Schwarzschild type I mirrors that had been fabricated for the EUVE mission have been determined. The techniques employed, the theoretical basis for the method, and the data that had been taken are presented. The measurements show that the best mirrors have a surface roughness of 20A rms or less.

  9. Vibrational effects in x-ray absorption and resonant inelastic x-ray scattering using a semiclassical scheme

    NASA Astrophysics Data System (ADS)

    Ljungberg, Mathias P.

    2017-12-01

    A method is presented for describing vibrational effects in x-ray absorption spectroscopy and resonant inelastic x-ray scattering (RIXS) using a combination of the classical Franck-Condon (FC) approximation and classical trajectories run on the core-excited state. The formulation of RIXS is an extension of the semiclassical Kramers-Heisenberg formalism of Ljungberg et al. [Phys. Rev. B 82, 245115 (2010), 10.1103/PhysRevB.82.245115] to the resonant case, retaining approximately the same computational cost. To overcome difficulties with connecting the absorption and emission processes in RIXS, the classical FC approximation is used for the absorption, which is seen to work well provided that a zero-point-energy correction is included. In the case of core-excited states with dissociative character, the method is capable of closely reproducing the main features for one-dimensional test systems, compared to the quantum-mechanical formulation. Due to the good accuracy combined with the relatively low computational cost, the method has great potential of being used for complex systems with many degrees of freedom, such as liquids and surface adsorbates.

  10. Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kunnus, Kristjan; Josefsson, Ida; Rajkovic, Ivan

    Here, ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbitalmore » and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO)5 in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given—which will be covered experimentally by upcoming transform-limited x-ray sources.« less

  11. Anti-Stokes resonant x-ray Raman scattering for atom specific and excited state selective dynamics

    DOE PAGES

    Kunnus, Kristjan; Josefsson, Ida; Rajkovic, Ivan; ...

    2016-10-07

    Here, ultrafast electronic and structural dynamics of matter govern rate and selectivity of chemical reactions, as well as phase transitions and efficient switching in functional materials. Since x-rays determine electronic and structural properties with elemental, chemical, orbital and magnetic selectivity, short pulse x-ray sources have become central enablers of ultrafast science. Despite of these strengths, ultrafast x-rays have been poor at picking up excited state moieties from the unexcited ones. With time-resolved anti-Stokes resonant x-ray Raman scattering (AS-RXRS) performed at the LCLS, and ab initio theory we establish background free excited state selectivity in addition to the elemental, chemical, orbitalmore » and magnetic selectivity of x-rays. This unparalleled selectivity extracts low concentration excited state species along the pathway of photo induced ligand exchange of Fe(CO)5 in ethanol. Conceptually a full theoretical treatment of all accessible insights to excited state dynamics with AS-RXRS with transform-limited x-ray pulses is given—which will be covered experimentally by upcoming transform-limited x-ray sources.« less

  12. An upgrade beamline for combined wide, small and ultra small-angle x-ray scattering at the ESRF

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Van Vaerenbergh, Pierre; Léonardon, Joachim; Sztucki, Michael

    2016-07-27

    This contribution presents the main design features of the upgraded beamline ID02 (TRUSAXS). The beamline combines different small-angle X-ray scattering techniques in one unique instrument. The key component of this instrument is an evacuated (5×10{sup −3} mbar) stainless steel detector tube of length 34 m and diameter 2 m. Three different detectors (Rayonix MX170, Pilatus 300 K and FReLoN 4M) are housed inside a motorized wagon which travels along a rail system with very low parasitic lateral movements (± 0.3 mm). This system allows automatically changing the sample-to-detector distance from about 1 m to 31 m and selecting the desiredmore » detector. In addition, a wide angle detector (Rayonix LX170) is installed just above the entrance cone of the tube for optional wide-angle X-ray scattering measurements. The beamstop system enables monitoring of the X-ray beam intensity in addition to blocking the primary beam, and automated insertion of selected masks behind the primary beamstop. The focusing optics and collimation system permit to cover a scattering vector (q) range of 0.002 nm{sup −1} ≤ q ≤ 50 nm{sup −1} with one unique setting using 0.1 nm X-ray wavelength for moderate flux (5×10{sup 12} photons/sec). However, for higher flux (6x10{sup 13} photons/sec) or higher resolution (minimum q < 0.001 nm{sup −1}), focusing and collimation, respectively need to be varied. For a sample-to-detector distance of 31 m and 0.1 nm wavelength, two dimensional ultra small-angle X-ray scattering patterns can be recorded down to q≈0.001 nm{sup −1} with far superior quality as compared to one dimensional profiles obtained with a Bonse-Hart instrument.« less

  13. Thorough small-angle X-ray scattering analysis of the instability of liquid micro-jets in air.

    PubMed

    Marmiroli, Benedetta; Cacho-Nerin, Fernando; Sartori, Barbara; Pérez, Javier; Amenitsch, Heinz

    2014-01-01

    Liquid jets are of interest, both for their industrial relevance and for scientific applications (more important, in particular for X-rays, after the advent of free-electron lasers that require liquid jets as sample carrier). Instability mechanisms have been described theoretically and by numerical simulation, but confirmed by few experimental techniques. In fact, these are mainly based on cameras, which is limited by the imaging resolution, and on light scattering, which is hindered by absorption, reflection, Mie scattering and multiple scattering due to complex air/liquid interfaces during jet break-up. In this communication it is demonstrated that synchrotron small-angle X-ray scattering (SAXS) can give quantitative information on liquid jet dynamics at the nanoscale, by detecting time-dependent morphology and break-up length. Jets ejected from circular tubes of different diameters (100-450 µm) and speeds (0.7-21 m s(-1)) have been explored to cover the Rayleigh and first wind-induced regimes. Various solvents (water, ethanol, 2-propanol) and their mixtures have been examined. The determination of the liquid jet behaviour becomes essential, as it provides background data in subsequent studies of chemical and biological reactions using SAXS or X-ray diffraction based on synchrotron radiation and free-electron lasers.

  14. Application of focused-beam flat-sample method to synchrotron powder X-ray diffraction with anomalous scattering effect

    NASA Astrophysics Data System (ADS)

    Tanaka, M.; Katsuya, Y.; Matsushita, Y.

    2013-03-01

    The focused-beam flat-sample method (FFM), which is a method for high-resolution and rapid synchrotron X-ray powder diffraction measurements by combination of beam focusing optics, a flat shape sample and an area detector, was applied for diffraction experiments with anomalous scattering effect. The advantages of FFM for anomalous diffraction were absorption correction without approximation, rapid data collection by an area detector and good signal-to-noise ratio data by focusing optics. In the X-ray diffraction experiments of CoFe2O4 and Fe3O4 (By FFM) using X-rays near the Fe K absorption edge, the anomalous scattering effect between Fe/Co or Fe2+/Fe3+ can be clearly detected, due to the change of diffraction intensity. The change of observed diffraction intensity as the incident X-ray energy was consistent with the calculation. The FFM is expected to be a method for anomalous powder diffraction.

  15. Correlations in Scattered X-Ray Laser Pulses Reveal Nanoscale Structural Features of Viruses

    NASA Astrophysics Data System (ADS)

    Kurta, Ruslan P.; Donatelli, Jeffrey J.; Yoon, Chun Hong; Berntsen, Peter; Bielecki, Johan; Daurer, Benedikt J.; DeMirci, Hasan; Fromme, Petra; Hantke, Max Felix; Maia, Filipe R. N. C.; Munke, Anna; Nettelblad, Carl; Pande, Kanupriya; Reddy, Hemanth K. N.; Sellberg, Jonas A.; Sierra, Raymond G.; Svenda, Martin; van der Schot, Gijs; Vartanyants, Ivan A.; Williams, Garth J.; Xavier, P. Lourdu; Aquila, Andrew; Zwart, Peter H.; Mancuso, Adrian P.

    2017-10-01

    We use extremely bright and ultrashort pulses from an x-ray free-electron laser (XFEL) to measure correlations in x rays scattered from individual bioparticles. This allows us to go beyond the traditional crystallography and single-particle imaging approaches for structure investigations. We employ angular correlations to recover the three-dimensional (3D) structure of nanoscale viruses from x-ray diffraction data measured at the Linac Coherent Light Source. Correlations provide us with a comprehensive structural fingerprint of a 3D virus, which we use both for model-based and ab initio structure recovery. The analyses reveal a clear indication that the structure of the viruses deviates from the expected perfect icosahedral symmetry. Our results anticipate exciting opportunities for XFEL studies of the structure and dynamics of nanoscale objects by means of angular correlations.

  16. Grazing-incidence small angle x-ray scattering studies of nanoscale polymer gratings

    NASA Astrophysics Data System (ADS)

    Doxastakis, Manolis; Suh, Hyo Seon; Chen, Xuanxuan; Rincon Delgadillo, Paulina A.; Wan, Lingshu; Williamson, Lance; Jiang, Zhang; Strzalka, Joseph; Wang, Jin; Chen, Wei; Ferrier, Nicola; Ramirez-Hernandez, Abelardo; de Pablo, Juan J.; Gronheid, Roel; Nealey, Paul

    2015-03-01

    Grazing-Incidence Small Angle X-ray Scattering (GISAXS) offers the ability to probe large sample areas, providing three-dimensional structural information at high detail in a thin film geometry. In this study we exploit the application of GISAXS to structures formed at one step of the LiNe (Liu-Nealey) flow using chemical patterns for directed self-assembly of block copolymer films. Experiments conducted at the Argonne National Laboratory provided scattering patterns probing film characteristics at both parallel and normal directions to the surface. We demonstrate the application of new computational methods to construct models based on scattering measured. Such analysis allows for extraction of structural characteristics at unprecedented detail.

  17. A small-angle x-ray scattering system with a vertical layout

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Zhen; Chen, Xiaowei; Meng, Lingpu

    A small-angle x-ray scattering (SAXS) system with a vertical layout (V-SAXS) has been designed and constructed for in situ detection on nanostructures, which is well suitable for in situ study on self-assembly of nanoparticles at liquid interface and polymer processing. A steel-tower frame on a reinforced basement is built as the supporting skeleton for scattering beam path and detector platform, ensuring the system a high working stability and a high operating accuracy. A micro-focus x-ray source combining parabolic three-dimensional multi-layer mirror and scatteringless collimation system provides a highly parallel beam, which allows us to detect the very small angle range.more » With a sample-to-detector distance of 7 m, the largest measurable length scale is 420 nm in real space. With a large sample zone, it is possible to install different experimental setups such as film stretching machine, which makes the system perfect to follow the microstructures evolution of materials during processing. The capability of the V-SAXS on in situ study is tested with a drying experiment of a free latex droplet, which confirms our initial design.« less

  18. A small-angle x-ray scattering system with a vertical layout.

    PubMed

    Wang, Zhen; Chen, Xiaowei; Meng, Lingpu; Cui, Kunpeng; Wu, Lihui; Li, Liangbin

    2014-12-01

    A small-angle x-ray scattering (SAXS) system with a vertical layout (V-SAXS) has been designed and constructed for in situ detection on nanostructures, which is well suitable for in situ study on self-assembly of nanoparticles at liquid interface and polymer processing. A steel-tower frame on a reinforced basement is built as the supporting skeleton for scattering beam path and detector platform, ensuring the system a high working stability and a high operating accuracy. A micro-focus x-ray source combining parabolic three-dimensional multi-layer mirror and scatteringless collimation system provides a highly parallel beam, which allows us to detect the very small angle range. With a sample-to-detector distance of 7 m, the largest measurable length scale is 420 nm in real space. With a large sample zone, it is possible to install different experimental setups such as film stretching machine, which makes the system perfect to follow the microstructures evolution of materials during processing. The capability of the V-SAXS on in situ study is tested with a drying experiment of a free latex droplet, which confirms our initial design.

  19. A method of measuring gold nanoparticle concentrations by x-ray fluorescence for biomedical applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu Di; Li Yuhua; Wong, Molly D.

    Purpose: This paper reports a technique that enables the quantitative determination of the concentration of gold nanoparticles (GNPs) through the accurate detection of their fluorescence radiation in the diagnostic x-ray spectrum. Methods: Experimentally, x-ray fluorescence spectra of 1.9 and 15 nm GNP solutions are measured using an x-ray spectrometer, individually and within chicken breast tissue samples. An optimal combination of excitation and emission filters is determined to segregate the fluorescence spectra at 66.99 and 68.80 keV from the background scattering. A roadmap method is developed that subtracts the scattered radiation (acquired before the insertion of GNP solutions) from the signalmore » radiation acquired after the GNP solutions are inserted. Results: The methods effectively minimize the background scattering in the spectrum measurements, showing linear relationships between GNP solutions from 0.1% to 10% weight concentration and from 0.1% to 1.0% weight concentration inside a chicken breast tissue sample. Conclusions: The investigation demonstrated the potential of imaging gold nanoparticles quantitatively in vivo for in-tissue studies, but future studies will be needed to investigate the ability to apply this method to clinical applications.« less

  20. Building a Unified Computational Model for the Resonant X-Ray Scattering of Strongly Correlated Materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bansil, Arun

    2016-12-01

    Basic-Energy Sciences of the Department of Energy (BES/DOE) has made large investments in x-ray sources in the U.S. (NSLS-II, LCLS, NGLS, ALS, APS) as powerful enabling tools for opening up unprecedented new opportunities for exploring properties of matter at various length and time scales. The coming online of the pulsed photon source literally allows us to see and follow the dynamics of processes in materials at their natural timescales. There is an urgent need therefore to develop theoretical methodologies and computational models for understanding how x-rays interact with matter and the related spectroscopies of materials. The present project addressed aspectsmore » of this grand challenge of X-ray science. In particular, our Collaborative Research Team (CRT) focused on understanding and modeling of elastic and inelastic resonant X-ray scattering processes. We worked to unify the three different computational approaches currently used for modeling X-ray scattering—density functional theory, dynamical mean-field theory, and small-cluster exact diagonalization—to achieve a more realistic material-specific picture of the interaction between X-rays and complex matter. To achieve a convergence in the interpretation and to maximize complementary aspects of different theoretical methods, we concentrated on the cuprates, where most experiments have been performed. Our team included both US and international researchers, and it fostered new collaborations between researchers currently working with different approaches. In addition, we developed close relationships with experimental groups working in the area at various synchrotron facilities in the US. Our CRT thus helped toward enabling the US to assume a leadership role in the theoretical development of the field, and to create a global network and community of scholars dedicated to X-ray scattering research.« less

  1. The small angle x-ray scattering of globular proteins in solution during heat denaturation

    NASA Astrophysics Data System (ADS)

    Banuelos, Jose; Urquidi, Jacob

    2008-10-01

    The ability of proteins to change their conformation in response to changes in their environment has consequences in biological processes like metabolism, chemical regulation in cells, and is believed to play a role in the onset of several neurodegenerative diseases. Factors such as a change in temperature, pressure, and the introduction of ions into the aqueous environment of a protein can give rise to the folding/unfolding of a protein. As a protein unfolds, the ratio of nonpolar to polar groups exposed to water changes, affecting a protein's thermodynamic properties. Using small angle x-ray scattering (SAXS), we are currently studying the intermediate protein conformations that arise during the folding/unfolding process as a function of temperature for five globular proteins. Trends in the observed intermediate structures of these globular proteins, along with correlations with data on protein thermodynamics may help elucidate shared characteristics between all proteins in the folding/unfolding process. Experimental design considerations will be discussed and preliminary results for some of these systems will be presented.

  2. Reflection thermal diffuse x-ray scattering for quantitative determination of phonon dispersion relations

    DOE PAGES

    Mei, A. B.; Hellman, O.; Schlepuetz, C. M.; ...

    2015-11-03

    Synchrotron reflection x-ray thermal diffuse scattering (TDS) measurements, rather than previously reported transmission TDS, are carried out at room temperature and analyzed using a formalism based upon second-order interatomic force constants and long-range Coulomb interactions to obtain quantitative determinations of MgO phonon dispersion relations (h) over bar omega(j) (q), phonon densities of states g((h) over bar omega), and isochoric temperature-dependent vibrational heat capacities c v (T). We use MgO as a model system for investigating reflection TDS due to its harmonic behavior as well as its mechanical and dynamic stability. Resulting phonon dispersion relations and densities of states are foundmore » to be in good agreement with independent reports from inelastic neutron and x-ray scattering experiments. Temperature-dependent isochoric heat capacities c v (T), computed within the harmonic approximation from (h) over bar omega(j) (q) values, increase with temperature from 0.4 x 10 -4 eV/atom K at 100 K to 1.4 x 10 -4 eV/atom K at 200 K and 1.9 x 10 -4 eV/atom K at 300 K, in excellent agreement with isobaric heat capacity values c p (T) between 4 and 300 K. We anticipate that the experimental approach developed here will be valuable for determining vibrational properties of heteroepitaxial thin films since the use of grazing-incidence (θ ≲ θ c where θ c is the density-dependent critical angle) allows selective tuning of x-ray penetration depths to ≲ 10 nm.« less

  3. Detection of X-ray photons by solution-processed organic-inorganic perovskites

    PubMed Central

    Yakunin, Sergii; Sytnyk, Mykhailo; Kriegner, Dominik; Shrestha, Shreetu; Richter, Moses; Matt, Gebhard J.; Azimi, Hamed; Brabec, Christoph J.; Stangl, Julian; Kovalenko, Maksym V.; Heiss, Wolfgang

    2017-01-01

    The evolution of real-time medical diagnostic tools such as angiography and computer tomography from radiography based on photographic plates was enabled by the development of integrated solid-state X-ray photon detectors, based on conventional solid-state semiconductors. Recently, for optoelectronic devices operating in the visible and near infrared spectral regions, solution-processed organic and inorganic semiconductors have also attracted immense attention. Here we demonstrate a possibility to use such inexpensive semiconductors for sensitive detection of X-ray photons by direct photon-to-current conversion. In particular, methylammonium lead iodide perovskite (CH3NH3PbI3) offers a compelling combination of fast photoresponse and a high absorption cross-section for X-rays, owing to the heavy Pb and I atoms. Solution processed photodiodes as well as photoconductors are presented, exhibiting high values of X-ray sensitivity (up to 25 µC mGyair-1 cm-3) and responsivity (1.9×104 carriers/photon), which are commensurate with those obtained by the current solid-state technology. PMID:28553368

  4. ASCA measurements of the grain-scattered X-ray halos of eclipsing massive X-ray binaries: Vela X-1 and Centaurus X-3

    NASA Technical Reports Server (NTRS)

    Woo, Jonathan W.; Clark, George W.; Day, Charles S. R.; Nagase, Fumiaki; Takeshima, Toshiaki

    1994-01-01

    We have measured the decaying dust-scattered X-ray halo of Cen X-3 during its binary eclipse with the ASCA solid-state imaging spectrometer (SIS). The surface brightness profile (SBP) of the image in the low-energy band (0.5-3 keV) lies substantially above the point-spread function (PSF) of the X-ray telescope, while the SBP in the high-energy band (5-10 keV) exhibits no significant deviation. By contrast, the SBPs of Vela X-1 during its eclipse are consistent with the PSF in both the low- and high-energy bands -- strong evidence that a dust halo is indeed present in Cen X-3. Accordingly, we modeled the SBP of Cen X-3 taken from six consecutive time segments under the principal assumptions that the dust is distributed uniformly along a segment of the line of sight, the grains have a power-law size distribution, and the low-energy source flux was the same function of orbital phase before as during our observation. The best-fit set of parameters included a grain density value of 1.3 g/cu cm, substanially less than the density of 'astronomical silicate.' This result supports the idea that interstellar grains are 'fluffy' aggregates of smaller solid particles. We attribute the failure to detect a halo of Vela X-1 during its eclipse phase to extended strong circumsource absorption that probably occurred before the eclipse and allowed the halo to decay away before the observation began.

  5. Ultra-high-resolution inelastic X-ray scattering at high-repetition-rate self-seeded X-ray free-electron lasers

    PubMed Central

    Chubar, Oleg; Geloni, Gianluca; Kocharyan, Vitali; Madsen, Anders; Saldin, Evgeni; Serkez, Svitozar; Shvyd’ko, Yuri; Sutter, John

    2016-01-01

    Inelastic X-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25 nm−1 spectral and momentum-transfer resolutions, respectively. However, further improvements down to 0.1 meV and 0.02 nm−1 are required to close the gap in energy–momentum space between high- and low-frequency probes. It is shown that this goal can be achieved by further optimizing the X-ray optics and by increasing the spectral flux of the incident X-ray pulses. UHRIX performs best at energies from 5 to 10 keV, where a combination of self-seeding and undulator tapering at the SASE-2 beamline of the European XFEL promises up to a 100-fold increase in average spectral flux compared with nominal SASE pulses at saturation, or three orders of magnitude more than what is possible with storage-ring-based radiation sources. Wave-optics calculations show that about 7 × 1012 photons s−1 in a 90 µeV bandwidth can be achieved on the sample. This will provide unique new possibilities for dynamics studies by IXS. PMID:26917127

  6. Ultra-high-resolution inelastic X-ray scattering at high-repetition-rate self-seeded X-ray free-electron lasers

    DOE PAGES

    Chubar, Oleg; Geloni, Gianluca; Kocharyan, Vitali; ...

    2016-03-01

    Inelastic X-ray scattering (IXS) is an important tool for studies of equilibrium dynamics in condensed matter. A new spectrometer recently proposed for ultra-high-resolution IXS (UHRIX) has achieved 0.6 meV and 0.25 nm ₋1spectral and momentum-transfer resolutions, respectively. However, further improvements down to 0.1 meV and 0.02 nm ₋1are required to close the gap in energy–momentum space between high- and low-frequency probes. It is shown that this goal can be achieved by further optimizing the X-ray optics and by increasing the spectral flux of the incident X-ray pulses. UHRIX performs best at energies from 5 to 10 keV, where a combinationmore » of self-seeding and undulator tapering at the SASE-2 beamline of the European XFEL promises up to a 100-fold increase in average spectral flux compared with nominal SASE pulses at saturation, or three orders of magnitude more than what is possible with storage-ring-based radiation sources. Wave-optics calculations show that about 7 × 10 12 photons s ₋1in a 90 µeV bandwidth can be achieved on the sample. Ultimately, this will provide unique new possibilities for dynamics studies by IXS.« less

  7. Real-time x-ray scattering study of the initial growth of organic crystals on polymer brushes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    An, Sung Yup; Ahn, Kwangseok; Kim, Doris Yangsoo

    2014-04-21

    We studied the early-stage growth structures of pentacene organic crystals grown on polymer brushes using real-time x-ray scattering techniques. In situ x-ray reflectivity and atomic force microscopy analyses revealed that at temperatures close to the glass transition temperature of polymer brush, the pentacene overlayer on a polymer brush film showed incomplete condensation and 3D island structures from the first monolayer. A growth model based on these observations was used to quantitatively analyze the real-time anti-Bragg x-ray scattering intensities measured during pentacene growth to obtain the time-dependent layer coverage of the individual pentacene monolayers. The extracted total coverage confirmed significant desorptionmore » and incomplete condensation in the pentacene films deposited on the polymer brushes. These effects are ascribed to the change in the surface viscoelasticity of the polymer brushes around the glass transition temperature.« less

  8. Interior tomographic imaging for x-ray coherent scattering (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Pang, Sean; Zhu, Zheyuan

    2017-05-01

    Conventional computed tomography reconstructs the attenuation only high-dimensional images. Coherent scatter computed tomography, which reconstructs the angular dependent scattering profiles of 3D objects, can provide molecular signatures that improves the accuracy of material identification and classification. Coherent scatter tomography are traditionally acquired by setups similar to x-ray powder diffraction machine; a collimated source in combination with 2D or 1D detector collimation in order to localize the scattering point. In addition, the coherent scatter cross-section is often 3 orders of magnitude lower than that of the absorption cross-section for the same material. Coded aperture and structured illumination approaches has been shown to greatly improve the collection efficiency. In many applications, especially in security imaging and medical diagnosis, fast and accurate identification of the material composition of a small volume within the whole object would lead to an accelerated imaging procedure and reduced radiation dose. Here, we report an imaging method to reconstruct the material coherent scatter profile within a small volume. The reconstruction along one radial direction can reconstruct a scalar coherent scattering tomographic image. Our methods takes advantage of the finite support of the scattering profile in small angle regime. Our system uses a pencil beam setup without using any detector side collimation. Coherent scatter profile of a 10 mm scattering sample embedded in a 30 mm diameter phantom was reconstructed. The setup has small form factor and is suitable for various portable non-destructive detection applications.

  9. Protein crowding in solution, frozen and freeze-dried states: small-angle neutron and X-ray scattering study of lysozyme/sorbitol/water systems

    NASA Astrophysics Data System (ADS)

    Krueger, Susan; Khodadadi, Sheila; Clark, Nicholas; McAuley, Arnold; Cristiglio, Viviana; Theyencheri, Narayanan; Curtis, Joseph; Shalaev, Evgenyi

    2015-03-01

    For effective preservation, proteins are often stored as frozen solutions or in glassy states using a freeze-drying process. However, aggregation is often observed after freeze-thaw or reconstitution of freeze-dried powder and the stability of the protein is no longer assured. In this study, small-angle neutron and X-ray scattering (SANS and SAXS) have been used to investigate changes in protein-protein interaction distances of a model protein/cryoprotectant system of lysozyme/sorbitol/water, under representative pharmaceutical processing conditions. The results demonstrate the utility of SAXS and SANS methods to monitor protein crowding at different stages of freezing and drying. The SANS measurements of solution samples showed at least one protein interaction peak corresponding to an interaction distance of ~ 90 Å. In the frozen state, two protein interaction peaks were observed by SANS with corresponding interaction distances at 40 Å as well as 90 Å. On the other hand, both SAXS and SANS data for freeze-dried samples showed three peaks, suggesting interaction distances ranging from ~ 15 Å to 170 Å. Possible interpretations of these interaction peaks will be discussed, as well as the role of sorbitol as a cryoprotectant during the freezing and drying process.

  10. Design and Tests of the Hard X-Ray Polarimeter X-Calibur

    NASA Technical Reports Server (NTRS)

    Beilicke, M.; Binns, W. R.; Buckley, J.; Cowsik, R.; Dowkontt, P.; Garson, A.; Guo, Q.; Israel, M. H.; Lee, K.; Krawczynski, H.; hide

    2011-01-01

    X-ray polarimetry promises to give new information about high-energy astrophysical sources, such as binary black hole systems, micro-quasars, active galactic nuclei, and gamma-ray bursts. We designed, built and tested a hard X-ray polarimeter X-Calibur to be used in the focal plane of the InFOC(mu)S grazing incidence hard X-ray telescope. X-Calibur combines a low-Z Compton scatterer with a CZT detector assembly to measure the polarization of 10-80 keV X-rays making use of the fact that polarized photons Compton scatter preferentially perpendicular to the electric field orientation. X-Calibur achieves a high detection efficiency of order unity.

  11. Design and Tests of the Hard X-Ray Polarimeter X-Calibur

    NASA Technical Reports Server (NTRS)

    Beilicke, M.; Baring, M. G.; Barthelmy, S.; Binns, W. R.; Buckley, J.; Cowsik, R.; Dowkontt, P.; Garson, A.; Guo, Q.; Haba, Y.; hide

    2012-01-01

    X-ray polarimetry promises to give qualitatively new information about high-energy astrophysical sources, such as binary black hole systems, micro-quasars, active galactic nuclei, and gamma-ray bursts. We designed, built and tested a hard X-ray polarimeter X-Calibur to be used in the focal plane of the InFOC(mu)S grazing incidence hard X-ray telescope. X-Calibur combines a low-Z Compton scatterer with a CZT detector assembly to measure the polarization of 10 - 80 keY X-rays making use of the fact that polarized photons Compton scatter preferentially perpendicular to the electric field orientation. X-Calibur achieves a high detection efficiency of order unity.

  12. Background radiation in inelastic X-ray scattering and X-ray emission spectroscopy. A study for Johann-type spectrometers

    NASA Astrophysics Data System (ADS)

    Paredes Mellone, O. A.; Bianco, L. M.; Ceppi, S. A.; Goncalves Honnicke, M.; Stutz, G. E.

    2018-06-01

    A study of the background radiation in inelastic X-ray scattering (IXS) and X-ray emission spectroscopy (XES) based on an analytical model is presented. The calculation model considers spurious radiation originated from elastic and inelastic scattering processes along the beam paths of a Johann-type spectrometer. The dependence of the background radiation intensity on the medium of the beam paths (air and helium), analysed energy and radius of the Rowland circle was studied. The present study shows that both for IXS and XES experiments the background radiation is dominated by spurious radiation owing to scattering processes along the sample-analyser beam path. For IXS experiments the spectral distribution of the main component of the background radiation shows a weak linear dependence on the energy for the most cases. In the case of XES, a strong non-linear behaviour of the background radiation intensity was predicted for energy analysis very close to the backdiffraction condition, with a rapid increase in intensity as the analyser Bragg angle approaches π / 2. The contribution of the analyser-detector beam path is significantly weaker and resembles the spectral distribution of the measured spectra. Present results show that for usual experimental conditions no appreciable structures are introduced by the background radiation into the measured spectra, both in IXS and XES experiments. The usefulness of properly calculating the background profile is demonstrated in a background subtraction procedure for a real experimental situation. The calculation model was able to simulate with high accuracy the energy dependence of the background radiation intensity measured in a particular XES experiment with air beam paths.

  13. X-ray Spectral Formation In High-mass X-ray Binaries: The Case Of Vela X-1

    NASA Astrophysics Data System (ADS)

    Akiyama, Shizuka; Mauche, C. W.; Liedahl, D. A.; Plewa, T.

    2007-05-01

    We are working to develop improved models of radiatively-driven mass flows in the presence of an X-ray source -- such as in X-ray binaries, cataclysmic variables, and active galactic nuclei -- in order to infer the physical properties that determine the X-ray spectra of such systems. The models integrate a three-dimensional time-dependent hydrodynamics capability (FLASH); a comprehensive and uniform set of atomic data, improved calculations of the line force multiplier that account for X-ray photoionization and non-LTE population kinetics, and X-ray emission-line models appropriate to X-ray photoionized plasmas (HULLAC); and a Monte Carlo radiation transport code that simulates Compton scattering and recombination cascades following photoionization. As a test bed, we have simulated a high-mass X-ray binary with parameters appropriate to Vela X-1. While the orbital and stellar parameters of this system are well constrained, the physics of X-ray spectral formation is less well understood because the canonical analytical wind velocity profile of OB stars does not account for the dynamical and radiative feedback effects due to the rotation of the system and to the irradiation of the stellar wind by X-rays from the neutron star. We discuss the dynamical wind structure of Vela X-1 as determined by the FLASH simulation, where in the binary the X-ray emission features originate, and how the spatial and spectral properties of the X-ray emission features are modified by Compton scattering, photoabsorption, and fluorescent emission. This work was performed under the auspices of the U.S. Department of Energy by University of California, Lawrence Livermore National Laboratory under Contract W-7405-Eng-48.

  14. Investigating the Defect Structures in Transparent Conducting Oxides Using X-ray and Neutron Scattering Techniques

    PubMed Central

    González, Gabriela B.

    2012-01-01

    Transparent conducting oxide (TCO) materials are implemented into a wide variety of commercial devices because they possess a unique combination of high optical transparency and high electrical conductivity. Created during the processing of the TCOs, defects within the atomic-scale structure are responsible for their desirable optical and electrical properties. Therefore, studying the defect structure is essential to a better understanding of the behavior of transparent conductors. X-ray and neutron scattering techniques are powerful tools to investigate the atomic lattice structural defects in these materials. This review paper presents some of the current developments in the study of structural defects in n-type TCOs using x-ray diffraction (XRD), neutron diffraction, extended x-ray absorption fine structure (EXAFS), pair distribution functions (PDFs), and x-ray fluorescence (XRF). PMID:28817010

  15. Correlations in Scattered X-Ray Laser Pulses Reveal Nanoscale Structural Features of Viruses

    DOE PAGES

    Kurta, Ruslan P.; Donatelli, Jeffrey J.; Yoon, Chun Hong; ...

    2017-10-12

    We use extremely bright and ultrashort pulses from an x-ray free-electron laser (XFEL) to measure correlations in x rays scattered from individual bioparticles. This allows us to go beyond the traditional crystallography and single-particle imaging approaches for structure investigations. We employ angular correlations to recover the three-dimensional (3D) structure of nanoscale viruses from x-ray diffraction data measured at the Linac Coherent Light Source. Correlations provide us with a comprehensive structural fingerprint of a 3D virus, which we use both for model-based and ab initio structure recovery. The analyses reveal a clear indication that the structure of the viruses deviates frommore » the expected perfect icosahedral symmetry. Lastly, our results anticipate exciting opportunities for XFEL studies of the structure and dynamics of nanoscale objects by means of angular correlations.« less

  16. Topographic measurement of buried thin-film interfaces using a grazing resonant soft x-ray scattering technique

    NASA Astrophysics Data System (ADS)

    Gann, Eliot; Watson, Anne; Tumbleston, John R.; Cochran, Justin; Yan, Hongping; Wang, Cheng; Seok, Jaewook; Chabinyc, Michael; Ade, Harald

    2014-12-01

    The internal structures of thin films, particularly interfaces between different materials, are critical to system properties and performance across many disciplines, but characterization of buried interface topography is often unfeasible. In this work, we demonstrate that grazing resonant soft x-ray scattering (GRSoXS), a technique measuring diffusely scattered soft x rays from grazing incidence, can reveal the statistical topography of buried thin-film interfaces. By controlling and predicting the x-ray electric field intensity throughout the depth of the film and simultaneously the scattering contrast between materials, we are able to unambiguously identify the microstructure at different interfaces of a model polymer bilayer system. We additionally demonstrate the use of GRSoXS to selectively measure the topography of the surface and buried polymer-polymer interface in an organic thin-film transistor, revealing different microstructure and markedly differing evolution upon annealing. In such systems, where only indirect control of interface topography is possible, accurate measurement of the structure of interfaces for feedback is critically important. While we demonstrate the method here using organic materials, we also show that the technique is readily extendable to any thin-film system with elemental or chemical contrasts exploitable at absorption edges.

  17. X-ray crystallography

    NASA Technical Reports Server (NTRS)

    2001-01-01

    X-rays diffracted from a well-ordered protein crystal create sharp patterns of scattered light on film. A computer can use these patterns to generate a model of a protein molecule. To analyze the selected crystal, an X-ray crystallographer shines X-rays through the crystal. Unlike a single dental X-ray, which produces a shadow image of a tooth, these X-rays have to be taken many times from different angles to produce a pattern from the scattered light, a map of the intensity of the X-rays after they diffract through the crystal. The X-rays bounce off the electron clouds that form the outer structure of each atom. A flawed crystal will yield a blurry pattern; a well-ordered protein crystal yields a series of sharp diffraction patterns. From these patterns, researchers build an electron density map. With powerful computers and a lot of calculations, scientists can use the electron density patterns to determine the structure of the protein and make a computer-generated model of the structure. The models let researchers improve their understanding of how the protein functions. They also allow scientists to look for receptor sites and active areas that control a protein's function and role in the progress of diseases. From there, pharmaceutical researchers can design molecules that fit the active site, much like a key and lock, so that the protein is locked without affecting the rest of the body. This is called structure-based drug design.

  18. Structural Significance of Lipid Diversity as Studied by Small Angle Neutron and X-ray Scattering

    DOE PAGES

    Kučerka, Norbert; Heberle, Frederick A.; Pan, Jianjun; ...

    2015-09-21

    In this paper, we review recent developments in the rapidly growing field of membrane biophysics, with a focus on the structural properties of single lipid bilayers determined by different scattering techniques, namely neutron and X-ray scattering. The need for accurate lipid structural properties is emphasized by the sometimes conflicting results found in the literature, even in the case of the most studied lipid bilayers. Increasingly, accurate and detailed structural models require more experimental data, such as those from contrast varied neutron scattering and X-ray scattering experiments that are jointly refined with molecular dynamics simulations. This experimental and computational approach producesmore » robust bilayer structural parameters that enable insights, for example, into the interplay between collective membrane properties and its components (e.g., hydrocarbon chain length and unsaturation, and lipid headgroup composition). Finally, from model studies such as these, one is better able to appreciate how a real biological membrane can be tuned by balancing the contributions from the lipid’s different moieties (e.g., acyl chains, headgroups, backbones, etc.).« less

  19. The complex ion structure of warm dense carbon measured by spectrally resolved x-ray scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kraus, D.; Barbrel, B.; Falcone, R. W.

    2015-05-15

    We present measurements of the complex ion structure of warm dense carbon close to the melting line at pressures around 100 GPa. High-pressure samples were created by laser-driven shock compression of graphite and probed by intense laser-generated x-ray sources with photon energies of 4.75 keV and 4.95 keV. High-efficiency crystal spectrometers allow for spectrally resolving the scattered radiation. Comparing the ratio of elastically and inelastically scattered radiation, we find evidence for a complex bonded liquid that is predicted by ab-initio quantum simulations showing the influence of chemical bonds under these conditions. Using graphite samples of different initial densities we demonstrate the capability ofmore » spectrally resolved x-ray scattering to monitor the carbon solid-liquid transition at relatively constant pressure of 150 GPa. Showing first single-pulse scattering spectra from cold graphite of unprecedented quality recorded at the Linac Coherent Light Source, we demonstrate the outstanding possibilities for future high-precision measurements at 4th Generation Light Sources.« less

  20. Low-angle X-ray scattering properties of irradiated spices

    NASA Astrophysics Data System (ADS)

    Almeida, A. P. G.; Braz, D.; Barroso, R. C.; Lopes, R. T.

    2007-09-01

    The scattering of X-rays at low angles (LAXS) is a technique dominated by the coherent scattering process. One characteristic observation of low-angle coherent scattering is the so-called molecular interference effect, being characterized by the presence of one or more peaks in the forward direction of scattering. In the present study, LAXS profiles from five different spices are carefully measured in order to establish characteristic scattering signatures. Samples of Ceylon cinnamon, cumin, nutmeg, paprika and black pepper were bought in local market in Rio de Janeiro, Brazil. The LAXS patterns were obtained using a Shimadzu DRX 6000 diffractometer in reflection geometry. Coherent scattering patterns are measured for the samples for θ=5-35°. The data were collected in 0.05° increments every 3 s. In order to evaluate the possible molecular structure changes caused to the irradiation procedure, the signatures obtained for control (non-irradiated) spices were compared with spice samples irradiated with different doses varying from 3 to 40 kGy. The LAXS patterns of all samples were obtained after 30, 60, 90, 120 days to evaluate the effect of storage period. Scattering profiles from spices irradiated with different irradiation doses were obtained and the results compared. For each spice, there is no considerable deviation in shape in function of the irradiation dose. It indicates that the molecular structure of each analyzed spices is preserved considering the dose range chosen. The results show that the molecular structure was found to be stable during storage at the ambient temperature for up to 4 months.

  1. An apparatus for in situ x-ray scattering measurements during polymer injection molding.

    PubMed

    Rendon, Stanley; Fang, Jun; Burghardt, Wesley R; Bubeck, Robert A

    2009-04-01

    We report a novel instrument for synchrotron-based in situ x-ray scattering measurements during injection molding processing. It allows direct, real-time monitoring of molecular-scale structural evolution in polymer materials undergoing a complex processing operation. The instrument is based on a laboratory-scale injection molding machine, and employs customized mold tools designed to allow x-ray access during mold filling and subsequent solidification, while providing sufficient robustness to withstand high injection pressures. The use of high energy, high flux synchrotron radiation, and a fast detector allows sufficiently rapid data acquisition to resolve time-dependent orientation dynamics in this transient process. Simultaneous monitoring of temperature and pressure signals allows transient scattering data to be referenced to various stages of the injection molding cycle. Representative data on a commercial liquid crystalline polymer, Vectra(R) B950, are presented to demonstrate the features of this apparatus; however, it may find application in a wide range of polymeric materials such as nanocomposites, semicrystalline polymers and fiber-reinforced thermoplastics.

  2. Simulation tools for scattering corrections in spectrally resolved x-ray computed tomography using McXtrace

    NASA Astrophysics Data System (ADS)

    Busi, Matteo; Olsen, Ulrik L.; Knudsen, Erik B.; Frisvad, Jeppe R.; Kehres, Jan; Dreier, Erik S.; Khalil, Mohamad; Haldrup, Kristoffer

    2018-03-01

    Spectral computed tomography is an emerging imaging method that involves using recently developed energy discriminating photon-counting detectors (PCDs). This technique enables measurements at isolated high-energy ranges, in which the dominating undergoing interaction between the x-ray and the sample is the incoherent scattering. The scattered radiation causes a loss of contrast in the results, and its correction has proven to be a complex problem, due to its dependence on energy, material composition, and geometry. Monte Carlo simulations can utilize a physical model to estimate the scattering contribution to the signal, at the cost of high computational time. We present a fast Monte Carlo simulation tool, based on McXtrace, to predict the energy resolved radiation being scattered and absorbed by objects of complex shapes. We validate the tool through measurements using a CdTe single PCD (Multix ME-100) and use it for scattering correction in a simulation of a spectral CT. We found the correction to account for up to 7% relative amplification in the reconstructed linear attenuation. It is a useful tool for x-ray CT to obtain a more accurate material discrimination, especially in the high-energy range, where the incoherent scattering interactions become prevailing (>50 keV).

  3. X-Ray Thomson Scattering and Radiography from Spherical Implosions on the OMEGA Laser

    NASA Astrophysics Data System (ADS)

    Saunders, A. M.; Laziki-Jenei, A.; Doeppner, T.; Landen, O. L.; MacDonald, M.; Nilsen, J.; Swift, D.; Falcone, R. W.

    2017-10-01

    X-ray Thomson scattering (XRTS) is an experimental technique that directly probes the physics of warm dense matter by measuring electron density, electron temperature, and ionization state. XRTS in combination with x-ray radiography offers a unique ability to measure an absolute equation of state (EOS) from material under compression. Recent experiments highlight uncertainties in EOS models and the predicted ionization of compressed matter, suggesting more validation of models is needed. We present XRTS and x-ray radiography measurements taken at the OMEGA Laser Facility from directly-driven solid carbon spheres at densities on the order of 1x1024 g cm-3 and temperatures on the order of 30 eV. The results shed light on the equations of state of matter under compression. This work performed under auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344 and under the Stewardship Science Graduate Fellowship, Grant Number DE- NA0002135.

  4. Beam Measurement of 11.424 GHz X-Band Linac for Compton Scattering X-ray Source

    NASA Astrophysics Data System (ADS)

    Natsui, Takuya; Mori, Azusa; Masuda, Hirotoshi; Uesaka, Mitsuru; Sakamoto, Fumito

    2010-11-01

    An inverse Compton scattering X-ray source for medical applications, consisting of an X-band (11.424 GHz) linac and Q-switched Nd:YAG laser, is currently being developed at the University of Tokyo. This system uses an X-band 3.5-cell thermionic cathode RF gun for electron beam generation. We can obtain a multi-bunch electron beam with this gun. The beam is accelerated to 30 MeV by a traveling-wave accelerating tube. So far, we have verified stable beam generation (around 2.3 MeV) by using the newly designed RF gun and we have succeeded in beam transportation to a beam dump.

  5. Incorporation of Cadmium and Nickel into Ferrite Spinel Solid Solution: X-ray Diffraction and X-ray Absorption Fine Structure Analyses.

    PubMed

    Su, Minhua; Liao, Changzhong; Chan, Tingshan; Shih, Kaimin; Xiao, Tangfu; Chen, Diyun; Kong, Lingjun; Song, Gang

    2018-01-16

    The feasibility of incorporating Cd and Ni in hematite was studied by investigating the interaction mechanism for the formation of Cd x Ni 1-x Fe 2 O 4 solid solutions (CNFs) from CdO, NiO, and α-Fe 2 O 3 . X-ray diffraction results showed that the CNFs crystallized into spinel structures with increasing lattice parameters as the Cd content in the precursors was increased. Cd 2+ ions were found to occupy the tetrahedral sites, as evidenced by Rietveld refinement and extended X-ray absorption fine structure analyses. The incorporation of Cd and Ni into ferrite spinel solid solution strongly relied on the processing parameters. The incorporation of Cd and Ni into the CNFs was greater at high x values (0.7 < x ≤ 1.0) than at low x values (0.0 ≤ x ≤ 0.7). A feasible treatment technique based on the investigated mechanism of CNF formation was developed, involving thermal treatment of waste sludge containing Cd and Ni. Both of these metals in the waste sludge were successfully incorporated into a ferrite spinel solid solution, and the concentrations of leached Cd and Ni from this solid solution were substantially reduced, stabilizing at low levels. This research offers a highly promising approach for treating the Cd and Ni content frequently encountered in electronic waste and its treatment residues.

  6. Determination of coal ash content by the combined x-ray fluorescence and scattering spectrum

    NASA Astrophysics Data System (ADS)

    Mikhailov, I. F.; Baturin, A. A.; Mikhailov, A. I.; Borisova, S. S.; Fomina, L. P.

    2018-02-01

    An alternative method is proposed for the determination of the inorganic constituent mass fraction (ash) in solid fuel by the ratio of Compton and Rayleigh X-ray scattering peaks IC/IR subject to the iron fluorescence intensity. An original X-ray optical scheme with a Ti/Mo (or Sc/Cu) double-layer secondary radiator allows registration of the combined fluorescence-and-scattering spectrum at the specified scattering angle. An algorithm for linear calibration of the Compton-to-Rayleigh IC/IR ratio is proposed which uses standard samples with two certified characteristics: mass fractions of ash (Ad) and iron oxide (WFe2O3). Ash mass fractions have been determined for coals of different deposits in the wide range of Ad from 9.4% to 52.7% mass and WFe2O3 from 0.3% to 4.95% mass. Due to the high penetrability of the probing radiation with energy E > 17 keV, the sample preparation procedure is rather simplified in comparison with the traditional method of Ad determination by the sum of fluorescence intensities of all constituent elements.

  7. Novel micro-reactor flow cell for investigation of model catalysts using in situ grazing-incidence X-ray scattering

    PubMed Central

    Kehres, Jan; Pedersen, Thomas; Masini, Federico; Andreasen, Jens Wenzel; Nielsen, Martin Meedom; Diaz, Ana; Nielsen, Jane Hvolbæk; Hansen, Ole

    2016-01-01

    The design, fabrication and performance of a novel and highly sensitive micro-reactor device for performing in situ grazing-incidence X-ray scattering experiments of model catalyst systems is presented. The design of the reaction chamber, etched in silicon on insulator (SIO), permits grazing-incidence small-angle X-ray scattering (GISAXS) in transmission through 10 µm-thick entrance and exit windows by using micro-focused beams. An additional thinning of the Pyrex glass reactor lid allows simultaneous acquisition of the grazing-incidence wide-angle X-ray scattering (GIWAXS). In situ experiments at synchrotron facilities are performed utilizing the micro-reactor and a designed transportable gas feed and analysis system. The feasibility of simultaneous in situ GISAXS/GIWAXS experiments in the novel micro-reactor flow cell was confirmed with CO oxidation over mass-selected Ru nanoparticles. PMID:26917133

  8. Classification of fracture and non-fracture groups by analysis of coherent X-ray scatter

    PubMed Central

    Dicken, A. J.; Evans, J. P. O.; Rogers, K. D.; Stone, N.; Greenwood, C.; Godber, S. X.; Clement, J. G.; Lyburn, I. D.; Martin, R. M.; Zioupos, P.

    2016-01-01

    Osteoporotic fractures present a significant social and economic burden, which is set to rise commensurately with the aging population. Greater understanding of the physicochemical differences between osteoporotic and normal conditions will facilitate the development of diagnostic technologies with increased performance and treatments with increased efficacy. Using coherent X-ray scattering we have evaluated a population of 108 ex vivo human bone samples comprised of non-fracture and fracture groups. Principal component fed linear discriminant analysis was used to develop a classification model to discern each condition resulting in a sensitivity and specificity of 93% and 91%, respectively. Evaluating the coherent X-ray scatter differences from each condition supports the hypothesis that a causal physicochemical change has occurred in the fracture group. This work is a critical step along the path towards developing an in vivo diagnostic tool for fracture risk prediction. PMID:27363947

  9. Clusters in intense x-ray pulses

    NASA Astrophysics Data System (ADS)

    Bostedt, Christoph

    2012-06-01

    Free-electron lasers can deliver extremely intense, coherent x-ray flashes with femtosecond pulse length, opening the door for imaging single nanoscale objects in a single shot. All matter irradiated by these intense x-ray pulses, however, will be transformed into a highly-excited non-equilibrium plasma within femtoseconds. During the x-ray pulse complex electron dynamics and the onset of atomic disorder will be induced, leading to a time-varying sample. We have performed first experiments about x-ray laser pulse -- cluster interaction with a combined spectroscopy and imaging approach at both, the FLASH free electron laser in Hamburg (Germany) and the LCLS x-ray free-electron laser in Stanford (California). Atomic clusters are ideal for investigating the light - matter interaction because their size can be tuned from the molecular to the bulk regime, thus allowing to distinguish between intra and inter atomic processes. Imaging experiments with xenon clusters show power-density dependent changes in the scattering patterns. Modeling the scattering data indicates that the optical constants of the clusters change during the femtosecond pulse due to the transient creation of high charge states. The results show that ultra fast scattering is a promising approach to study transient states of matter on a femtosecond time scale. Coincident recording of time-of-flight spectra and scattering patterns allows the deconvolution of focal volume and particle size distribution effects. Single-shot single-particle experiments with keV x-rays reveal that for the highest power densities an highly excited and hot cluster plasma is formed for which recombination is suppressed. Time resolved infrared pump -- x-ray probe experiments have started. Here, the clusters are pumped into a nanoplasma state and their time evolution is probed with femtosecond x-ray scattering. The data show strong variations in the scattering patterns stemming from electronic reconfigurations in the cluster

  10. Resonant Soft X-ray Scattering studies with Transition Edge Sensors

    NASA Astrophysics Data System (ADS)

    Fang, Yizhi; Lee, Sangjun; de La Pena, Gilberto; Sun, Xiaolan; Rodolakis, Fanny; McChesney, Jessica; Fowler, Joe; Joe, Young Il; Doriese, William; Morgan, Kelsey; Swetz, Daniel; Ullom, Joel; Abbamonte, Peter

    Resonant Soft X-ray has been one of the key techniques to study charge orders in high Tc cuperates. To solve the issue of unwanted enhancement of inelastic florescence background at resonance, we have developed an energy-resolving superconducting Transition-Edge Sensor microcalorimeters. These superconducting sensors obtain exquisite energy resolution by exploiting the superconducting-to-normal transition to photon energy and by operating at cryogenic temperatures ( 70 mK) where thermal noise is minimal. This TES has demonstrated 1.0 eV resolution below 1 keV. We present first results using this detector to study the (002) Bragg peak and specular elastic scattering from a single crystal of stripe-ordered La 2 - x Bax CuO4 (x=0.125). Use of this detector for studying excitations and rejecting background fluorescence will be discussed.

  11. A potential for overestimating the absolute magnitudes of second virial coefficients by small-angle X-ray scattering.

    PubMed

    Scott, David J; Patel, Trushar R; Winzor, Donald J

    2013-04-15

    Theoretical consideration is given to the effect of cosolutes (including buffer and electrolyte components) on the determination of second virial coefficients for proteins by small-angle X-ray scattering (SAXS)-a factor overlooked in current analyses in terms of expressions for a two-component system. A potential deficiency of existing practices is illustrated by reassessment of published results on the effect of polyethylene glycol concentration on the second virial coefficient for urate oxidase. This error reflects the substitution of I(0,c3,0), the scattering intensity in the limit of zero scattering angle and solute concentration, for I(0,0,0), the corresponding parameter in the limit of zero cosolute concentration (c3) as well. Published static light scattering results on the dependence of the apparent molecular weight of ovalbumin on buffer concentration are extrapolated to zero concentration to obtain the true value (M2) and thereby establish the feasibility of obtaining the analogous SAXS parameter, I(0,0,0), experimentally. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. THE TRANSIENT ACCRETING X-RAY PULSAR XTE J1946+274: STABILITY OF X-RAY PROPERTIES AT LOW FLUX AND UPDATED ORBITAL SOLUTION

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Marcu-Cheatham, Diana M.; Pottschmidt, Katja; Kühnel, Matthias

    2015-12-10

    We present a timing and spectral analysis of the X-ray pulsar XTE J1946+274 observed with Suzaku during an outburst decline in 2010 October and compare with previous results. XTE J1946+274 is a transient X-ray binary consisting of a Be-type star and a neutron star with a 15.75 s pulse period in a 172 days orbit with 2–3 outbursts per orbit during phases of activity. We improve the orbital solution using data from multiple instruments. The X-ray spectrum can be described by an absorbed Fermi–Dirac cut-off power-law model along with a narrow Fe Kα line at 6.4 keV and a weakmore » Cyclotron Resonance Scattering Feature (CRSF) at ∼35 keV. The Suzaku data are consistent with the previously observed continuum flux versus iron line flux correlation expected from fluorescence emission along the line of sight. However, the observed iron line flux is slightly higher, indicating the possibility of a higher iron abundance or the presence of non-uniform material. We argue that the source most likely has only been observed in the subcritical (non-radiation dominated) state since its pulse profile is stable over all observed luminosities and the energy of the CRSF is approximately the same at the highest (∼5 × 10{sup 37} erg s{sup −1}) and lowest (∼5 × 10{sup 36} erg s{sup −1}) observed 3–60 keV luminosities.« less

  13. Unraveling skyrmion spin texture using resonant soft x-ray scattering

    NASA Astrophysics Data System (ADS)

    Roy, Sujoy

    2015-03-01

    The recent discovery of skyrmions, that were originally predicted in context of high energy physics, in magnetic materials has sparked tremendous interest in the research community due to its rich physics and potential in spintronics applications. Skyrmions have an unusual spin texture that manifests as magnetic knot and can be easily moved around. Understanding the fundamental physics and mechanisms for controlling their dynamical properties presents important scientific challenges. So far experimental verifications of the skyrmions in magnetic systems have come from neutron scattering and Lorentz transmission electron microscopy (TEM) measurements. In this talk we report the first observation of the skyrmions using resonant soft x-ray scattering. We have used soft x-rays tuned to the Cu L3 edge to diffract off the skyrmion lattice in a multiferroic Cu2OSeO3 compound. We show that in Cu2OSeO3 there exist two skyrmion lattices arising due to the two inequivalent Cu-O sublattices that have two different magnetically active d-orbitals. The two skyrmion sublattices are mutually rotated with respect to each other. The angle of rotation could be changed by an external magnetic field, thereby indicating possible existence of a new phase. We have also studied skyrmion spin texture in an ultra-thin Fe/Gd multilayer that shows perpendicular anisotropy. The Fe/Gd sample exhibits a near perfect aligned stripe phase. Within a small range of temperature and magnetic field we observe a hexagonal scattering pattern due to skyrmion bubbles. Analysis of the scattering pattern suggests that the skyrmion lattice unit cell contains two skyrmions. The biskyrmion state is also revealed by Lorentz TEM images. The near room temperature discovery of skyrmion in a technology relevant material is a significant step towards using skyrmions in magnetic devices. Work at LBNL was supported by the Office of Basic Energy Sciences of the U.S. Department of Energy (Contract No. DE-AC02-05CH11231).

  14. Antibodies under pressure: A Small-Angle X-ray Scattering study of Immunoglobulin G under high hydrostatic pressure.

    PubMed

    König, Nico; Paulus, Michael; Julius, Karin; Schulze, Julian; Voetz, Matthias; Tolan, Metin

    2017-12-01

    In the present work two subclasses of the human antibody Immunoglobulin G (IgG) have been investigated by Small-Angle X-ray Scattering under high hydrostatic pressures up to 5kbar. It is shown that IgG adopts a symmetric T-shape in solution which differs significantly from available crystal structures. Moreover, high-pressure experiments verify the high stability of the IgG molecule. It is not unfolded by hydrostatic pressures of up to 5kbar but a slight increase of the radius of gyration was observed at elevated pressures. Copyright © 2017 Elsevier B.V. All rights reserved.

  15. Quantitative X-ray mapping, scatter diagrams and the generation of correction maps to obtain more information about your material

    NASA Astrophysics Data System (ADS)

    Wuhrer, R.; Moran, K.

    2014-03-01

    Quantitative X-ray mapping with silicon drift detectors and multi-EDS detector systems have become an invaluable analysis technique and one of the most useful methods of X-ray microanalysis today. The time to perform an X-ray map has reduced considerably with the ability to map minor and trace elements very accurately due to the larger detector area and higher count rate detectors. Live X-ray imaging can now be performed with a significant amount of data collected in a matter of minutes. A great deal of information can be obtained from X-ray maps. This includes; elemental relationship or scatter diagram creation, elemental ratio mapping, chemical phase mapping (CPM) and quantitative X-ray maps. In obtaining quantitative x-ray maps, we are able to easily generate atomic number (Z), absorption (A), fluorescence (F), theoretical back scatter coefficient (η), and quantitative total maps from each pixel in the image. This allows us to generate an image corresponding to each factor (for each element present). These images allow the user to predict and verify where they are likely to have problems in our images, and are especially helpful to look at possible interface artefacts. The post-processing techniques to improve the quantitation of X-ray map data and the development of post processing techniques for improved characterisation are covered in this paper.

  16. Resonant inelastic soft x-ray scattering of CdS: a two-dimensional electronic structure map approach

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weinhardt, L.; Fuchs, O.; Fleszar, A.

    2008-09-24

    Resonant inelastic x-ray scattering (RIXS) with soft x-rays is uniquely suited to study the elec-tronic structure of a variety of materials, but is currently limited by low (fluorescence yield) count rates. This limitation is overcome with a new high-transmission spectrometer that allows to measure soft x-ray RIXS"maps." The S L2,3 RIXS map of CdS is discussed and compared with density functional calculations. The map allows the extraction of decay channel-specific"absorp-tion spectra," giving detailed insight into the wave functions of occupied and unoccupied elec-tronic states.

  17. X-ray scattering study of the spin-Peierls phase transition

    NASA Astrophysics Data System (ADS)

    Lumsden, Mark Douglas

    1999-11-01

    + dopant ion. Relative lattice constant measurements indicate spontaneous strains which scale with the square of the order parameter for the doped samples as was the case for pure CuGeO3. X-ray scattering measurements of both the order parameter and critical scattering in the vicinity of the transition temperature have been performed for the organic spin-Peierls compound MEM(TCNQ)2. Order parameter measurements indicate a value of the exponent beta of 0.35 +/- 0.06 consistent with 3D universality, as was observed in the inorganic spin-Peierls material CuGeO3, and inconsistent with previous measurements which suggested mean-field behaviour. Critical scattering measurements suggest a lineshape not described by a traditional Ornstein-Zernike, Lorentzian, form but well described by a Lorentzian with a varying power or a Lorentzian+Lorentzian 2. The latter form is reminiscent of recent x-ray scattering measurements of critical phenomena associated with structural phase transitions in perovskites or with magnetic x-ray scattering measurements on Ho, Tb, and some U-based compounds. Differences between this and previous measurements are discussed.

  18. An explosives detection system for airline security using coherent x-ray scattering technology

    NASA Astrophysics Data System (ADS)

    Madden, Robert W.; Mahdavieh, Jacob; Smith, Richard C.; Subramanian, Ravi

    2008-08-01

    L-3 Communications Security and Detection Systems (SDS) has developed a new system for automated alarm resolution in airline baggage Explosive Detection Systems (EDS) based on coherent x-ray scattering spectroscopy. The capabilities of the system were demonstrated in tests with concealed explosives at the Transportation Security Laboratory and airline passenger baggage at Orlando International Airport. The system uses x-ray image information to identify suspicious objects and performs targeted diffraction measurements to classify them. This extra layer of detection capability affords a significant reduction in the rate of false alarm objects that must presently be resolved by opening passenger bags for hand inspection.

  19. Introducing a New Capability at SSRL: Resonant Soft X-ray Scattering

    NASA Astrophysics Data System (ADS)

    Lee, Jun-Sik; Jang, Hoyoung; Lu, Donghui; Kao, Chi-Chang

    Stanford Synchrotron Radiation Lightsource (SSRL) at SLAC recently developed a setup for the resonant soft x-ray scattering (RSXS). In general, the RSXS technique uniquely probes not only structural information, but also chemical specific information. This is because this technique can explore the spatial periodicities of charge, orbital, spin, and lattice with spectroscopic aspect. Moreover, the soft x-ray range is particularly relevant for a study of soft materials as it covers the K-edge of C, N, F, and O, as well as the L-edges of transition metals and M-edges of rare-earth elements. Hence, the RSXS capability has been regarded as a very powerful technique for investigating the intrinsic properties of materials such as quantum- and energy-materials. The RSXS capability at the SSRL composes of in-vacuum 4-circle diffractometer. There are also the fully motorized sample-motion manipulations. Also, the sample can be cooled down to 25 K via the liquid helium. This capability has been installed at BL 13-3, where the photon source is from elliptically polarized undulator (EPU). Covering the photon energies is from 230 eV to 1400 eV. Furthermore, this EPU system offers more degree of freedoms for controlling x-ray polarizations (linear and circular). Using the advance of controlling x-ray polarization, we can also investigate a morphology effect of local domain/grain in materials. The detailed introduction of the RSXS end-station and several results will be touched in this poster presentation.

  20. Final Report - X-ray Studies of Highly Correlated Systems

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Burns, Clement

    2017-11-27

    The overall goal of the research was to improve the capabilities of x-ray synchrotron instrumentation to enable cutting-edge research in condensed matter physics. The main goal of the current grant cycle was to find a method to measure the polarization of the scattered x-ray in resonant inelastic x-ray scattering. To do this, we developed a polarization analysis apparatus using a thin, toroidally bent single crystal, which could be set to reflect one or the other of the two polarization components in the scattered x-ray beam. Resonant x-ray scattering measurements were also carried out on interfaces and the charge density wavemore » in high temperature superconducting materials.« less

  1. A comprehensive model for x-ray projection imaging system efficiency and image quality characterization in the presence of scattered radiation

    NASA Astrophysics Data System (ADS)

    Monnin, P.; Verdun, F. R.; Bosmans, H.; Rodríguez Pérez, S.; Marshall, N. W.

    2017-07-01

    This work proposes a method for assessing the detective quantum efficiency (DQE) of radiographic imaging systems that include both the x-ray detector and the antiscatter device. Cascaded linear analysis of the antiscatter device efficiency (DQEASD) with the x-ray detector DQE is used to develop a metric of system efficiency (DQEsys); the new metric is then related to the existing system efficiency parameters of effective DQE (eDQE) and generalized DQE (gDQE). The effect of scatter on signal transfer was modelled through its point spread function (PSF), leading to an x-ray beam transfer function (BTF) that multiplies with the classical presampling modulation transfer function (MTF) to give the system MTF. Expressions are then derived for the influence of scattered radiation on signal-difference to noise ratio (SDNR) and contrast-detail (c-d) detectability. The DQEsys metric was tested using two digital mammography systems, for eight x-ray beams (four with and four without scatter), matched in terms of effective energy. The model was validated through measurements of contrast, SDNR and MTF for poly(methyl)methacrylate thicknesses covering the range of scatter fractions expected in mammography. The metric also successfully predicted changes in c-d detectability for different scatter conditions. Scatter fractions for the four beams with scatter were established with the beam stop method using an extrapolation function derived from the scatter PSF, and validated through Monte Carlo (MC) simulations. Low-frequency drop of the MTF from scatter was compared to both theory and MC calculations. DQEsys successfully quantified the influence of the grid on SDNR and accurately gave the break-even object thickness at which system efficiency was improved by the grid. The DQEsys metric is proposed as an extension of current detector characterization methods to include a performance evaluation in the presence of scattered radiation, with an antiscatter device in place.

  2. A 2 m inelastic x-ray scattering spectrometer at CMC-XOR, Advanced Photon Source.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hill, J. P.; Coburn, D. S.; Kim, Y. J.

    2007-07-01

    The design and commissioning of an inelastic X-ray scattering instrument at CMC-XOR at the Advanced Photon Source is reported. The instrument features a 2 m vertical-scattering arm with a novel counterweight design to reduce the twisting moment as the arm is moved in the scattering plane. A Ge(733) spherical analyzer was fabricated and an overall resolution of 118 meV (FWHM) was obtained with a Si(444) monochromator and a Si(111) pre-monochromator. Early results from a representative cuprate, La{sub 2}CuO{sub 4}, are reported.

  3. Diagnostics for the optimization of an 11 keV inverse Compton scattering x-ray source

    NASA Astrophysics Data System (ADS)

    Chauchat, A.-S.; Brasile, J.-P.; Le Flanchec, V.; Nègre, J.-P.; Binet, A.; Ortega, J.-M.

    2013-04-01

    In a scope of a collaboration between Thales Communications & Security and CEA DAM DIF, 11 keV Xrays were produced by inverse Compton scattering on the ELSA facility. In this type of experiment, X-ray observation lies in the use of accurate electron and laser beam interaction diagnostics and on fitted X-ray detectors. The low interaction probability between < 100 μm width, 12 ps [rms] length electron and photon pulses requires careful optimization of pulse spatial and temporal covering. Another issue was to observe 11 keV X-rays in the ambient radioactive noise of the linear accelerator. For that, we use a very sensitive detection scheme based on radio luminescent screens.

  4. Characterization of Protein Flexibility Using Small-Angle X-Ray Scattering and Amplified Collective Motion Simulations

    PubMed Central

    Wen, Bin; Peng, Junhui; Zuo, Xiaobing; Gong, Qingguo; Zhang, Zhiyong

    2014-01-01

    Large-scale flexibility within a multidomain protein often plays an important role in its biological function. Despite its inherent low resolution, small-angle x-ray scattering (SAXS) is well suited to investigate protein flexibility and determine, with the help of computational modeling, what kinds of protein conformations would coexist in solution. In this article, we develop a tool that combines SAXS data with a previously developed sampling technique called amplified collective motions (ACM) to elucidate structures of highly dynamic multidomain proteins in solution. We demonstrate the use of this tool in two proteins, bacteriophage T4 lysozyme and tandem WW domains of the formin-binding protein 21. The ACM simulations can sample the conformational space of proteins much more extensively than standard molecular dynamics (MD) simulations. Therefore, conformations generated by ACM are significantly better at reproducing the SAXS data than are those from MD simulations. PMID:25140431

  5. Quantitative characterization of fatty liver disease using x-ray scattering

    NASA Astrophysics Data System (ADS)

    Elsharkawy, Wafaa B.; Elshemey, Wael M.

    2013-11-01

    Nonalcoholic fatty liver disease (NAFLD) is a dynamic condition in which fat abnormally accumulates within the hepatocytes. It is believed to be a marker of risk of later chronic liver diseases, such as liver cirrhosis and carcinoma. The fat content in liver biopsies determines its validity for liver transplantation. Transplantation of livers with severe NAFLD is associated with a high risk of primary non-function. Moreover, NAFLD is recognized as a clinically important feature that influences patient morbidity and mortality after hepatic resection. Unfortunately, there is a lack in a precise, reliable and reproducible method for quantification of NAFLD. This work suggests a method for the quantification of NAFLD. The method is based on the fact that fatty liver tissue would have a characteristic x-ray scattering profile with a relatively intense fat peak at a momentum transfer value of 1.1 nm-1 compared to a soft tissue peak at 1.6 nm-1. The fat content in normal and fatty liver is plotted against three profile characterization parameters (ratio of peak intensities, ratio of area under peaks and ratio of area under fat peak to total profile area) for measured and Monte Carlo simulated x-ray scattering profiles. Results show a high linear dependence (R2>0.9) of the characterization parameters on the liver fat content with a reported high correlation coefficient (>0.9) between measured and simulated data. These results indicate that the current method probably offers reliable quantification of fatty liver disease.

  6. X-ray Scattering Measurement of the Heat Capacity Ratio in Shock Compressed Matter

    NASA Astrophysics Data System (ADS)

    Fortmann, C.; Lee, H. J.; Doeppner, Tilo; Kritcher, A. L.; Landen, O. L.; Falcone, R. W.; Glenzer, S. H.

    2011-10-01

    We developed accurate x-ray scattering techniques to measure properties of matter under extreme conditions of density and temperature in intense laser-solid interaction experiments. We report on novel applications of x-ray scattering to measure the heat-capacity ratio γ =cp /cv of a Be plasma which determines the equation of state of the system. Ultraintense laser radiation is focussed onto both sides of a Be foil, creating two counterpropagating planar shock waves that collide in the target center. A second set of lasers produces Zn He- α radiation of 8.9 keV energy that scatters from the shock-compressed matter. We observe temperatures of 10eV and 15eV and mass densities of 5g/cm3 and 11g/cm3 before and after the shock collision. Applying the Rankine-Hugoniot relations for counterpropagating shocks we then infer γ as a function of density using only the measured mass compression ratios. Our results agree with equation of state models and DFT simulations. This work performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract DE-AC52-07NA27344. We acknowledge support from the Alexander von Humboldt-Foundation.

  7. Quantitative Characterization of Configurational Space Sampled by HIV-1 Nucleocapsid Using Solution NMR, X-ray Scattering and Protein Engineering.

    PubMed

    Deshmukh, Lalit; Schwieters, Charles D; Grishaev, Alexander; Clore, G Marius

    2016-06-03

    Nucleic-acid-related events in the HIV-1 replication cycle are mediated by nucleocapsid, a small protein comprising two zinc knuckles connected by a short flexible linker and flanked by disordered termini. Combining experimental NMR residual dipolar couplings, solution X-ray scattering and protein engineering with ensemble simulated annealing, we obtain a quantitative description of the configurational space sampled by the two zinc knuckles, the linker and disordered termini in the absence of nucleic acids. We first compute the conformational ensemble (with an optimal size of three members) of an engineered nucleocapsid construct lacking the N- and C-termini that satisfies the experimental restraints, and then validate this ensemble, as well as characterize the disordered termini, using the experimental data from the full-length nucleocapsid construct. The experimental and computational strategy is generally applicable to multidomain proteins. Differential flexibility within the linker results in asymmetric motion of the zinc knuckles which may explain their functionally distinct roles despite high sequence identity. One of the configurations (populated at a level of ≈40 %) closely resembles that observed in various ligand-bound forms, providing evidence for conformational selection and a mechanistic link between protein dynamics and function. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  8. Experimental characterization of an ultra-fast Thomson scattering x-ray source with three-dimensional time and frequency-domain analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kuba, J; Slaughter, D R; Fittinghoff, D N

    We present a detailed comparison of the measured characteristics of Thomson backscattered x-rays produced at the PLEIADES (Picosecond Laser-Electron Interaction for the Dynamic Evaluation of Structures) facility at Lawrence Livermore National Laboratory to predicted results from a newly developed, fully three-dimensional time and frequency-domain code. Based on the relativistic differential cross section, this code has the capability to calculate time and space dependent spectra of the x-ray photons produced from linear Thomson scattering for both bandwidth-limited and chirped incident laser pulses. Spectral broadening of the scattered x-ray pulse resulting from the incident laser bandwidth, perpendicular wave vector components in themore » laser focus, and the transverse and longitudinal phase space of the electron beam are included. Electron beam energy, energy spread, and transverse phase space measurements of the electron beam at the interaction point are presented, and the corresponding predicted x-ray characteristics are determined. In addition, time-integrated measurements of the x-rays produced from the interaction are presented, and shown to agree well with the simulations.« less

  9. SU-E-I-77: X-Ray Coherent Scatter Diffraction Pattern Modeling in GEANT4.

    PubMed

    Kapadia, A; Samei, E; Harrawood, B; Sahbaee, P; Chawla, A; Tan, Z; Brady, D

    2012-06-01

    To model X-ray coherent scatter diffraction patterns in GEANT4 for simulating experiments involving material detection through diffraction pattern measurement. Although coherent scatter cross-sections are modeled accurately in GEANT4, diffraction patterns for crystalline materials are not yet included. Here we describe our modeling of crystalline diffraction patterns in GEANT4 for specific materials and the validation of the results against experimentally measured data. Coherent scatter in GEANT4 is currently based on Hubbell's non-relativistic form factor tabulations from EPDL97. We modified the form-factors by introducing an interference function that accounts for the angular dependence between the Rayleigh-scattered photons and the photon wavelength. The modified form factors were used to replace the inherent form-factors in GEANT4. The simulation was tested using monochromatic and polychromatic x-ray beams (separately) incident on objects containing one or more elements with modified form-factors. The simulation results were compared against the experimentally measured diffraction images of corresponding objects using an in-house x-ray diffraction imager for validation. The comparison was made using the following metrics: number of diffraction rings, radial distance, absolute intensity, and relative intensity. Sharp diffraction pattern rings were observed in the monochromatic simulations at locations consistent with the angular dependence of the photon wavelength. In the polychromatic simulations, the diffraction patterns exhibited a radial blur consistent with the energy spread of the polychromatic spectrum. The simulated and experimentally measured patterns showed identical numbers of rings with close agreement in radial distance, absolute and relative intensities (barring statistical fluctuations). No significant change was observed in the execution time of the simulations. This work demonstrates the ability to model coherent scatter diffraction in GEANT4 in

  10. A liquid jet setup for x-ray scattering experiments on complex liquids at free-electron laser sources

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Steinke, I.; Lehmkühler, F., E-mail: felix.lehmkuehler@desy.de; Schroer, M. A.

    2016-06-15

    In this paper we describe a setup for x-ray scattering experiments on complex fluids using a liquid jet. The setup supports Small and Wide Angle X-ray Scattering (SAXS/WAXS) geometries. The jet is formed by a gas-dynamic virtual nozzle (GDVN) allowing for diameters ranging between 1 μm and 20 μm at a jet length of several hundred μm. To control jet properties such as jet length, diameter, or flow rate, the instrument is equipped with several diagnostic tools. Three microscopes are installed to quantify jet dimensions and stability in situ. The setup has been used at several beamlines performing both SAXSmore » and WAXS experiments. As a typical example we show an experiment on a colloidal dispersion in a liquid jet at the X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source free-electron laser.« less

  11. A liquid jet setup for x-ray scattering experiments on complex liquids at free-electron laser sources

    DOE PAGES

    Steinke, I.; Walther, M.; Lehmkühler, F.; ...

    2016-06-01

    In this study we describe a setup for x-ray scattering experiments on complex fluids using a liquid jet. The setup supports Small and Wide Angle X-ray Scattering (SAXS/WAXS) geometries. The jet is formed by a gas-dynamic virtual nozzle (GDVN) allowing for diameters ranging between 1 μm and 20 μm at a jet length of several hundred μm. To control jet properties such as jet length, diameter, or flow rate, the instrument is equipped with several diagnostic tools. Three microscopes are installed to quantify jet dimensions and stability in situ. The setup has been used at several beamlines performing both SAXSmore » and WAXS experiments. Finally, as a typical example we show an experiment on a colloidal dispersion in a liquid jet at the X-ray Correlation Spectroscopy instrument at the Linac Coherent Light Source free-electron laser.« less

  12. Crystallohydrodynamics of Protein Assemblies: Combining Sedimentation, Viscometry, and X-Ray Scattering

    PubMed Central

    Lu, Yanling; Longman, Emma; Davis, Kenneth G.; Ortega, Álvaro; Grossmann, J. Günter; Michaelsen, Terje E.; de la Torre, José García; Harding, Stephen E.

    2006-01-01

    Crystallohydrodynamics describes the domain orientation in solution of antibodies and other multidomain protein assemblies where the crystal structures may be known for the domains but not the intact structure. The approach removes the necessity for an ad hoc assumed value for protein hydration. Previous studies have involved only the sedimentation coefficient leading to considerable degeneracy or multiplicity of possible models for the conformation of a given protein assembly, all agreeing with the experimental data. This degeneracy can be considerably reduced by using additional solution parameters. Conformation charts are generated for the three universal (i.e., size-independent) shape parameters P (obtained from the sedimentation coefficient or translational diffusion coefficient), ν (from the intrinsic viscosity), and G (from the radius of gyration), and calculated for a wide range of plausible orientations of the domains (represented as bead-shell ellipsoidal models derived from their crystal structures) and after allowance for any linker or hinge regions. Matches are then sought with the set of functions P, ν, and G calculated from experimental data (allowing for experimental error). The number of solutions can be further reduced by the employment of the Dmax parameter (maximum particle dimension) from x-ray scattering data. Using this approach we are able to reduce the degeneracy of possible solution models for IgG3 to a possible representative structure in which the Fab domains are directed away from the plane of the Fc domain, a structure in accord with the recognition that IgG3 is the most efficient complement activator among human IgG subclasses. PMID:16766619

  13. Compton scattering artifacts in electron excited X-ray spectra measured with a silicon drift detector.

    PubMed

    Ritchie, Nicholas W M; Newbury, Dale E; Lindstrom, Abigail P

    2011-12-01

    Artifacts are the nemesis of trace element analysis in electron-excited energy dispersive X-ray spectrometry. Peaks that result from nonideal behavior in the detector or sample can fool even an experienced microanalyst into believing that they have trace amounts of an element that is not present. Many artifacts, such as the Si escape peak, absorption edges, and coincidence peaks, can be traced to the detector. Others, such as secondary fluorescence peaks and scatter peaks, can be traced to the sample. We have identified a new sample-dependent artifact that we attribute to Compton scattering of energetic X-rays generated in a small feature and subsequently scattered from a low atomic number matrix. It seems likely that this artifact has not previously been reported because it only occurs under specific conditions and represents a relatively small signal. However, with the advent of silicon drift detectors and their utility for trace element analysis, we anticipate that more people will observe it and possibly misidentify it. Though small, the artifact is not inconsequential. Under some conditions, it is possible to mistakenly identify the Compton scatter artifact as approximately 1% of an element that is not present.

  14. X-Ray Scattering Studies of the Liquid-Vapor Interface of Gallium.

    NASA Astrophysics Data System (ADS)

    Kawamoto, Eric Hitoshi

    A UHV system was developed for performing X-ray scattering studies and in situ analyses of liquid metal surfaces. A nearly ideal choice for this study, gallium has a melting point just above room temperature; is amenable to handling in both air and vacuum; its surface oxides can be removed while its cleanliness is maintained and monitored. Using argon glow-discharge sputtering techniques to remove intervening surface oxides, thin wetting layers of gallium were prepared atop nonreactive substrates, to be used as samples suited for liquid surface scattering experiments. Preliminary measurements of X-ray reflectivity from the liquid-vapor interface of gallium were performed with the X-ray UHV chamber configured for use in conjunction with liquid surface spectrometers at two synchrotron beamlines. A novel technique for carrying out and interpreting scattering measurements from curved liquid surfaces was demonstrated. The energy tunability and intense focused white beam flux from a wiggler source was shown to place within reach the large values of wavevector transfer at which specular reflectivity data yield small length scale information about surface structure. Various theoretical treatments and simulations predict quasi-lamellar ordering of atoms near the free surface of metallic liquids due to energetics particular to metals (electron delocalization, the dependence of system energy on ion and electron densities, surface tension and electrostatic energy). However, the experimental data reported to date is insufficient to distinguish between a monotonic, sigmoidal electron density profile found at the free surfaces of dielectric liquids, and the damped oscillatory layer-like profiles anticipated for metallic liquids. Out to a wavevector transfer of Q = 0.55 A ^{-1}, the reflectivity data measured from a curved Ga surface is not inconsistent with what is expected for a liquid-vapor electron density profile of Gaussian width sigma = 1.3 +/- 0.2 A. Subsequent

  15. High-energy magnetic excitations in overdoped La 2-xSr xCuO 4 studied by neutron and resonant inelastic X-ray scattering

    DOE PAGES

    Wakimoto, S.; Ishii, K.; Kimura, H.; ...

    2015-05-21

    We have performed neutron inelastic scattering and resonant inelastic x-ray scattering (RIXS) at the Cu-L 3 edge to study high-energy magnetic excitations at energy transfers of more than 100 meV for overdoped La 2₋xSr xCuO 4 with x=0.25 (T c=15 K) and x=0.30 (nonsuperconducting) using identical single-crystal samples for the two techniques. From constant-energy slices of neutron-scattering cross sections, we have identified magnetic excitations up to ~250 meV for x=0.25. Although the width in the momentum direction is large, the peak positions along the (π,π) direction agree with the dispersion relation of the spin wave in the nondoped La 2CuOmore » 4 (LCO), which is consistent with the previous RIXS results of cuprate superconductors. Using RIXS at the Cu-L 3 edge, we have measured the dispersion relations of the so-called paramagnon mode along both (π,π) and (π,0) directions. Although in both directions the neutron and RIXS data connect with each other and the paramagnon along (π,0) agrees well with the LCO spin-wave dispersion, the paramagnon in the (π,π) direction probed by RIXS appears to be less dispersive and the excitation energy is lower than the spin wave of LCO near (π/2,π/2). Thus, our results indicate consistency between neutron inelastic scattering and RIXS, and elucidate the entire magnetic excitation in the (π,π) direction by the complementary use of two probes. The polarization dependence of the RIXS profiles indicates that appreciable charge excitations exist in the same energy range of magnetic excitations, reflecting the itinerant character of the overdoped sample. Lastly, we find a possible anisotropy in the charge excitation intensity might explain the apparent differences in the paramagnon dispersion in the (π,π) direction as detected by the x-ray scattering.« less

  16. Energy-angle correlation correction algorithm for monochromatic computed tomography based on Thomson scattering X-ray source

    NASA Astrophysics Data System (ADS)

    Chi, Zhijun; Du, Yingchao; Huang, Wenhui; Tang, Chuanxiang

    2017-12-01

    The necessity for compact and relatively low cost x-ray sources with monochromaticity, continuous tunability of x-ray energy, high spatial coherence, straightforward polarization control, and high brightness has led to the rapid development of Thomson scattering x-ray sources. To meet the requirement of in-situ monochromatic computed tomography (CT) for large-scale and/or high-attenuation materials based on this type of x-ray source, there is an increasing demand for effective algorithms to correct the energy-angle correlation. In this paper, we take advantage of the parametrization of the x-ray attenuation coefficient to resolve this problem. The linear attenuation coefficient of a material can be decomposed into a linear combination of the energy-dependent photoelectric and Compton cross-sections in the keV energy regime without K-edge discontinuities, and the line integrals of the decomposition coefficients of the above two parts can be determined by performing two spectrally different measurements. After that, the line integral of the linear attenuation coefficient of an imaging object at a certain interested energy can be derived through the above parametrization formula, and monochromatic CT can be reconstructed at this energy using traditional reconstruction methods, e.g., filtered back projection or algebraic reconstruction technique. Not only can monochromatic CT be realized, but also the distributions of the effective atomic number and electron density of the imaging object can be retrieved at the expense of dual-energy CT scan. Simulation results validate our proposal and will be shown in this paper. Our results will further expand the scope of application for Thomson scattering x-ray sources.

  17. H-bonding in liquid acetamide as studied by x-ray scattering

    NASA Astrophysics Data System (ADS)

    Nasr, Salah; Ghédira, Mounir; Cortès, Robert

    1999-06-01

    A structural investigation of liquid acetamide was performed at 346 K using x-ray scattering. The data are analyzed to yield the molecular structure factor and the distinct pair correlation function. Two H-bonds per molecule are found on average. The mean N⋯O distance is about 3.03 Å. The liquid structure can be described by some structural units similar to the ones existing either in the rhombohedral or in the orthorhombic crystalline form.

  18. Flat panel X-ray detector with reduced internal scattering for improved attenuation accuracy and dynamic range

    DOEpatents

    Smith, Peter D [Santa Fe, NM; Claytor, Thomas N [White Rock, NM; Berry, Phillip C [Albuquerque, NM; Hills, Charles R [Los Alamos, NM

    2010-10-12

    An x-ray detector is disclosed that has had all unnecessary material removed from the x-ray beam path, and all of the remaining material in the beam path made as light and as low in atomic number as possible. The resulting detector is essentially transparent to x-rays and, thus, has greatly reduced internal scatter. The result of this is that x-ray attenuation data measured for the object under examination are much more accurate and have an increased dynamic range. The benefits of this improvement are that beam hardening corrections can be made accurately, that computed tomography reconstructions can be used for quantitative determination of material properties including density and atomic number, and that lower exposures may be possible as a result of the increased dynamic range.

  19. Line focus x-ray tubes—a new concept to produce high brilliance x-rays

    NASA Astrophysics Data System (ADS)

    Bartzsch, Stefan; Oelfke, Uwe

    2017-11-01

    Currently hard coherent x-ray radiation at high photon fluxes can only be produced with large and expensive radiation sources, such as 3rd generation synchrotrons. Especially in medicine, this limitation prevents various promising developments in imaging and therapy from being translated into clinical practice. Here we present a new concept of highly brilliant x-ray sources, line focus x-ray tubes (LFXTs), which may serve as a powerful and cheap alternative to synchrotrons and a range of other existing technologies. LFXTs employ an extremely thin focal spot and a rapidly rotating target for the electron beam which causes a change in the physical mechanism of target heating, allowing higher electron beam intensities at the focal spot. Monte Carlo simulations and numeric solutions of the heat equation are used to predict the characteristics of the LFXT. In terms of photon flux and coherence length, the performance of the line focus x-ray tube compares with inverse Compton scattering sources. Dose rates of up to 180 Gy s-1 can be reached in 50 cm distance from the focal spot. The results demonstrate that the line focus tube can serve as a powerful compact source for phase contrast imaging and microbeam radiation therapy. The production of a prototype seems technically feasible.

  20. Resonant soft X-ray scattering study of twist bend nematic, cholesteric and blue phases.

    NASA Astrophysics Data System (ADS)

    Slamonczyk, Miroslaw; Grecka, Ewa; Vaupotic, Natasa; Pociecha, Damian; Gleesom, Jim; Jakli, Antal; Sprunt, Sam; Wang, Cheng; Hexemer, Alexander; Zhu, Chenhui

    We have demonstrated that, when operated at carbon K-edge, the linearly polarized soft X-rays can enable bond orientation sensitivity, which can be utilized to probe the otherwise forbidden peak from the helices of twist bend nematic and helical nanofilament phase. Here we show that the same principle can be used to probe blue phase and chiral nematic phase. Furthermore, we discuss the relationship between the incoming linearly polarized X-rays, and the anisotropy in the scattering pattern. Office of Science, Office of Basic Energy Sciences, of the U.S. Department of Energy under Contract No. DE-AC02- 05CH11231.

  1. The magnetic order of GdMn₂Ge₂ studied by neutron diffraction and x-ray resonant magnetic scattering.

    PubMed

    Granovsky, S A; Kreyssig, A; Doerr, M; Ritter, C; Dudzik, E; Feyerherm, R; Canfield, P C; Loewenhaupt, M

    2010-06-09

    The magnetic structure of GdMn₂Ge₂ (tetragonal I4/mmm) has been studied by hot neutron powder diffraction and x-ray resonant magnetic scattering techniques. These measurements, along with the results of bulk experiments, confirm the collinear ferrimagnetic structure with moment direction parallel to the c-axis below T(C) = 96 K and the collinear antiferromagnetic phase in the temperature region T(C) < T < T(N) = 365 K. In the antiferromagnetic phase, x-ray resonant magnetic scattering has been detected at Mn K and Gd L₂ absorption edges. The Gd contribution is a result of an induced Gd 5d electron polarization caused by the antiferromagnetic order of Mn-moments.

  2. Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS

    DOE PAGES

    MacDonald, M. J.; Gorkhover, T.; Bachmann, B.; ...

    2016-08-08

    Atomic clusters can serve as ideal model systems for exploring ultrafast (~100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally-resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities and ionization. Single shot x-ray Thomson scatterings signals were recorded at 120 Hz using a crystal spectrometer in combination withmore » a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. As a result, such measurements are important for understanding collective effects in laser-matter interactions on femtosecond timescales, opening new routes for the development of schemes for their ultrafast control.« less

  3. Measurement of high-dynamic range x-ray Thomson scattering spectra for the characterization of nano-plasmas at LCLS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    MacDonald, M. J., E-mail: macdonm@umich.edu; SLAC National Accelerator Laboratory, Menlo Park, California 94025; Gorkhover, T.

    2016-11-15

    Atomic clusters can serve as ideal model systems for exploring ultrafast (∼100 fs) laser-driven ionization dynamics of dense matter on the nanometer scale. Resonant absorption of optical laser pulses enables heating to temperatures on the order of 1 keV at near solid density conditions. To date, direct probing of transient states of such nano-plasmas was limited to coherent x-ray imaging. Here we present the first measurement of spectrally resolved incoherent x-ray scattering from clusters, enabling measurements of transient temperature, densities, and ionization. Single shot x-ray Thomson scattering signals were recorded at 120 Hz using a crystal spectrometer in combination withmore » a single-photon counting and energy-dispersive pnCCD. A precise pump laser collimation scheme enabled recording near background-free scattering spectra from Ar clusters with an unprecedented dynamic range of more than 3 orders of magnitude. Such measurements are important for understanding collective effects in laser-matter interactions on femtosecond time scales, opening new routes for the development of schemes for their ultrafast control.« less

  4. Development of Si-APD Timing Detectors for Nuclear Resonant Scattering using High-energy Synchrotron X-rays

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kishimoto, Shunji; Zhang Xiaowei; Yoda, Yoshitaka

    2007-01-19

    A timing detector with silicon avalanche photodiodes (Si-APDs) has been developed for nuclear resonant scattering using synchrotron x-rays. The detector had four pairs of a germanium plate 0.1mm thick and a Si-APD (3 mm in dia., a depletion layer of 30-{mu}m thickness). Using synchrotron x-rays of 67.4 keV, the efficiency increased to 1.5% for the incident beam, while the efficiency was 0.76 % without the germanium converters. A measurement of SR-PAC on Ni-61 was executed by using the detector. Some other types of timing detectors are planned for x-rays of E>20 keV.

  5. Small angle x-ray scattering of chromatin. Radius and mass per unit length depend on linker length.

    PubMed Central

    Williams, S P; Langmore, J P

    1991-01-01

    Analyses of low angle x-ray scattering from chromatin, isolated by identical procedures but from different species, indicate that fiber diameter and number of nucleosomes per unit length increase with the amount of nucleosome linker DNA. Experiments were conducted at physiological ionic strength to obtain parameters reflecting the structure most likely present in living cells. Guinier analyses were performed on scattering from solutions of soluble chromatin from Necturus maculosus erythrocytes (linker length 48 bp), chicken erythrocytes (linker length 64 bp), and Thyone briareus sperm (linker length 87 bp). The results were extrapolated to infinite dilution to eliminate interparticle contributions to the scattering. Cross-sectional radii of gyration were found to be 10.9 +/- 0.5, 12.1 +/- 0.4, and 15.9 +/- 0.5 nm for Necturus, chicken, and Thyone chromatin, respectively, which are consistent with fiber diameters of 30.8, 34.2, and 45.0 nm. Mass per unit lengths were found to be 6.9 +/- 0.5, 8.3 +/- 0.6, and 11.8 +/- 1.4 nucleosomes per 10 nm for Necturus, chicken, and Thyone chromatin, respectively. The geometrical consequences of the experimental mass per unit lengths and radii of gyration are consistent with a conserved interaction among nucleosomes. Cross-linking agents were found to have little effect on fiber external geometry, but significant effect on internal structure. The absolute values of fiber diameter and mass per unit length, and their dependencies upon linker length agree with the predictions of the double-helical crossed-linker model. A compilation of all published x-ray scattering data from the last decade indicates that the relationship between chromatin structure and linker length is consistent with data obtained by other investigators. Images FIGURE 1 PMID:2049522

  6. Compact x-ray source based on burst-mode inverse Compton scattering at 100 kHz

    DOE PAGES

    Graves, W.  S.; Bessuille, J.; Brown, P.; ...

    2014-12-01

    A design for a compact x-ray light source (CXLS) with flux and brilliance orders of magnitude beyond existing laboratory scale sources is presented. The source is based on inverse Compton scattering of a high brightness electron bunch on a picosecond laser pulse. The accelerator is a novel high-efficiency standingwave linac and rf photoinjector powered by a single ultrastable rf transmitter at X-band rf frequency. The high efficiency permits operation at repetition rates up to 1 kHz, which is further boosted to 100 kHz by operating with trains of 100 bunches of 100 pC charge, each separated by 5 ns. Themore » entire accelerator is approximately 1 meter long and produces hard x rays tunable over a wide range of photon energies. The colliding laser is a Yb:YAG solid-state amplifier producing 1030 nm, 100 mJ pulses at the same 1 kHz repetition rate as the accelerator. The laser pulse is frequency-doubled and stored for many passes in a ringdown cavity to match the linac pulse structure. At a photon energy of 12.4 keV, the predicted x-ray flux is 5 × 10¹¹ photons/second in a 5% bandwidth and the brilliance is 2 × 10¹² photons/(sec mm² mrad² 0.1%) in pulses with rms pulse length of 490 fs. The nominal electron beam parameters are 18 MeV kinetic energy, 10 microamp average current, 0.5 microsecond macropulse length, resulting in average electron beam power of 180 W. Optimization of the x-ray output is presented along with design of the accelerator, laser, and x-ray optic components that are specific to the particular characteristics of the Compton scattered x-ray pulses.« less

  7. Analysis of RNA structure using small-angle X-ray scattering

    PubMed Central

    Cantara, William A.; Olson, Erik D.; Musier-Forsyth, Karin

    2016-01-01

    In addition to their role in correctly attaching specific amino acids to cognate tRNAs, aminoacyl-tRNA synthetases (aaRS) have been found to possess many alternative functions and often bind to and act on other nucleic acids. In contrast to the well-defined 3D structure of tRNA, the structures of many of the other RNAs recognized by aaRSs have not been solved. Despite advances in the use of X-ray crystallography (XRC), nuclear magnetic resonance (NMR) spectroscopy and cryo-electron microscopy (cryo-EM) for structural characterization of biomolecules, significant challenges to solving RNA structures still exist. Recently, small-angle X-ray scattering (SAXS) has been increasingly employed to characterize the 3D structures of RNAs and RNA-protein complexes. SAXS is capable of providing low-resolution tertiary structure information under physiological conditions and with less intensive sample preparation and data analysis requirements than XRC, NMR and cryo-EM. In this article, we describe best practices involved in the process of RNA and RNA-protein sample preparation, SAXS data collection, data analysis, and structural model building. PMID:27777026

  8. Ambient dose equivalent and effective dose from scattered x-ray spectra in mammography for Mo/Mo, Mo/Rh and W/Rh anode/filter combinations.

    PubMed

    Künzel, R; Herdade, S B; Costa, P R; Terini, R A; Levenhagen, R S

    2006-04-21

    In this study, scattered x-ray distributions were produced by irradiating a tissue equivalent phantom under clinical mammographic conditions by using Mo/Mo, Mo/Rh and W/Rh anode/filter combinations, for 25 and 30 kV tube voltages. Energy spectra of the scattered x-rays have been measured with a Cd(0.9)Zn(0.1)Te (CZT) detector for scattering angles between 30 degrees and 165 degrees . Measurement and correction processes have been evaluated through the comparison between the values of the half-value layer (HVL) and air kerma calculated from the corrected spectra and measured with an ionization chamber in a nonclinical x-ray system with a W/Mo anode/filter combination. The shape of the corrected x-ray spectra measured in the nonclinical system was also compared with those calculated using semi-empirical models published in the literature. Scattered x-ray spectra measured in the clinical x-ray system have been characterized through the calculation of HVL and mean photon energy. Values of the air kerma, ambient dose equivalent and effective dose have been evaluated through the corrected x-ray spectra. Mean conversion coefficients relating the air kerma to the ambient dose equivalent and to the effective dose from the scattered beams for Mo/Mo, Mo/Rh and W/Rh anode/filter combinations were also evaluated. Results show that for the scattered radiation beams the ambient dose equivalent provides an overestimate of the effective dose by a factor of about 5 in the mammography energy range. These results can be used in the control of the dose limits around a clinical unit and in the calculation of more realistic protective shielding barriers in mammography.

  9. Attosecond Thomson-scattering x-ray source driven by laser-based electron acceleration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Luo, W.; College of Science, National University of Defense Technology, Changsha 410073; Zhuo, H. B.

    2013-10-21

    The possibility of producing attosecond x-rays through Thomson scattering of laser light off laser-driven relativistic electron beams is investigated. For a ≤200-as, tens-MeV electron bunch produced with laser ponderomotive-force acceleration in a plasma wire, exceeding 10{sup 6} photons/s in the form of ∼160 as pulses in the range of 3–300 keV are predicted, with a peak brightness of ≥5 × 10{sup 20} photons/(s mm{sup 2} mrad{sup 2} 0.1% bandwidth). Our study suggests that the physical scheme discussed in this work can be used for an ultrafast (attosecond) x-ray source, which is the most beneficial for time-resolved atomic physics, dubbed “attosecondmore » physics.”.« less

  10. Effects of interstellar dust scattering on the X-ray eclipses of the LMXB AX J1745.6-2901 in the Galactic Centre

    NASA Astrophysics Data System (ADS)

    Jin, Chichuan; Ponti, Gabriele; Haberl, Frank; Smith, Randall; Valencic, Lynne

    2018-07-01

    AX J1745.6-2901 is an eclipsing low-mass X-ray binary in the Galactic Centre (GC). It shows significant X-ray excess emission during the eclipse phase, and its eclipse light curve shows an asymmetric shape. We use archival XMM-Newton and Chandra observations to study the origin of these peculiar X-ray eclipsing phenomena. We find that the shape of the observed X-ray eclipse light curves depends on both photon energy and the shape of the source extraction region, and also shows differences between the two instruments. By performing detailed simulations for the time-dependent X-ray dust-scattering halo, as well as directly modelling the observed eclipse and non-eclipse halo profiles of AX J1745.6-2901, we obtained solid evidence that its peculiar eclipse phenomena are indeed caused by the X-ray dust scattering in multiple foreground dust layers along the line of sight (LOS). The apparent dependence on the instruments is caused by different instrumental point spread functions. Our results can be used to assess the influence of dust-scattering in other eclipsing X-ray sources, and raise the importance of considering the timing effects of dust-scattering halo when studying the variability of other X-ray sources in the GC, such as Sgr A⋆. Moreover, our study of halo eclipse reinforces the existence of a dust layer local to AX J1745.6-2901 as reported by Jin et al. (2017), as well as identifying another dust layer within a few hundred parsecs to the Earth, containing up to several tens of percent LOS dust, which is likely to be associated with the molecular clouds in the Solar neighbourhood. The remaining LOS dust is likely to be associated with the molecular clouds located in the Galactic disc in-between.

  11. A compact permanent-magnet system for measuring magnetic circular dichroism in resonant inelastic soft X-ray scattering.

    PubMed

    Miyawaki, Jun; Suga, Shigemasa; Fujiwara, Hidenori; Niwa, Hideharu; Kiuchi, Hisao; Harada, Yoshihisa

    2017-03-01

    A compact and portable magnet system for measuring magnetic dichroism in resonant inelastic soft X-ray scattering (SX-RIXS) has been developed at the beamline BL07LSU in SPring-8. A magnetic circuit composed of Nd-Fe-B permanent magnets, which realised ∼0.25 T at the center of an 11 mm gap, was rotatable around the axis perpendicular to the X-ray scattering plane. Using the system, a SX-RIXS spectrum was obtained under the application of the magnetic field at an angle parallel, nearly 45° or perpendicular to the incident X-rays. A dedicated sample stage was also designed to be as compact as possible, making it possible to perform SX-RIXS measurements at arbitrary incident angles by rotating the sample stage in the gap between the magnetic poles. This system enables facile studies of magnetic dichroism in SX-RIXS for various experimental geometries of the sample and the magnetic field. A brief demonstration of the application is presented.

  12. Small-angle x-ray scattering in amorphous silicon: A computational study

    NASA Astrophysics Data System (ADS)

    Paudel, Durga; Atta-Fynn, Raymond; Drabold, David A.; Elliott, Stephen R.; Biswas, Parthapratim

    2018-05-01

    We present a computational study of small-angle x-ray scattering (SAXS) in amorphous silicon (a -Si) with particular emphasis on the morphology and microstructure of voids. The relationship between the scattering intensity in SAXS and the three-dimensional structure of nanoscale inhomogeneities or voids is addressed by generating large high-quality a -Si networks with 0.1%-0.3% volume concentration of voids, as observed in experiments using SAXS and positron annihilation spectroscopy. A systematic study of the variation of the scattering intensity in the small-angle scattering region with the size, shape, number density, and the spatial distribution of the voids in the networks is presented. Our results suggest that the scattering intensity in the small-angle region is particularly sensitive to the size and the total volume fraction of the voids, but the effect of the geometry or shape of the voids is less pronounced in the intensity profiles. A comparison of the average size of the voids obtained from the simulated values of the intensity, using the Guinier approximation and Kratky plots, with that of the same from the spatial distribution of the atoms in the vicinity of void surfaces is presented.

  13. Inelastic X-ray scattering of RTAl3 (R = La, Ce, T = Cu, Au)

    NASA Astrophysics Data System (ADS)

    Tsutsui, Satoshi; Kaneko, Koji; Pospisil, Jiri; Haga, Yoshinori

    2018-05-01

    Inelastic X-ray scattering (IXS) experiments of RTAl3 (R = La Ce, T = Cu, Au) were carried out at 300 and 5.5 K. The spectra between LaCuAl3 and CeCuAl3 (LaAuAl3 and CeAuAl3) are nearly identical at both temperatures except for temperature factors such as temperature dependence of Bose factor in IXS spectra and effect on thermal expansion. This means that no evident temperature dependence of IXS spectra was observed in CeTAl3 (T = Cu, Au). Since the major contribution of scattering cross section in IXS measurements is Thomson scattering, the present results failed to confirm the presence of vibron in these compounds.

  14. Versatile application of indirect Fourier transformation to structure factor analysis: from X-ray diffraction of molecular liquids to small angle scattering of protein solutions.

    PubMed

    Fukasawa, Toshiko; Sato, Takaaki

    2011-02-28

    We highlight versatile applicability of a structure-factor indirect Fourier transformation (IFT) technique, hereafter called SQ-IFT. The original IFT aims at the pair distance distribution function, p(r), of colloidal particles from small angle scattering of X-rays (SAXS) and neutrons (SANS), allowing the conversion of the experimental form factor, P(q), into a more intuitive real-space spatial autocorrelation function. Instead, SQ-IFT is an interaction potential model-free approach to the 'effective' or 'experimental' structure factor to yield the pair correlation functions (PCFs), g(r), of colloidal dispersions like globular protein solutions for small-angle scattering data as well as the radial distribution functions (RDFs) of molecular liquids in liquid diffraction (LD) experiments. We show that SQ-IFT yields accurate RDFs of liquid H(2)O and monohydric alcohol reflecting their local intermolecular structures, in which q-weighted structure function, qH(q), conventionally utilized in many LD studies out of necessity of performing direct Fourier transformation, is no longer required. We also show that SQ-IFT applied to theoretically calculated structure factors for uncharged and charged colloidal dispersions almost perfectly reproduces g(r) obtained as a solution of the Ornstein-Zernike (OZ) equation. We further demonstrate the relevance of SQ-IFT in its practical applications, using SANS effective structure factors of lysozyme solutions reported in recent literatures which revealed the equilibrium cluster formation due to coexisting long range electrostatic repulsion and short range attraction between the proteins. Finally, we present SAXS experiments on human serum albumin (HSA) at different ionic strength and protein concentration, in which we discuss the real space picture of spatial distributions of the proteins via the interaction potential model-free route.

  15. Internal protein motions in molecular-dynamics simulations of Bragg and diffuse X-ray scattering.

    PubMed

    Wall, Michael E

    2018-03-01

    Molecular-dynamics (MD) simulations of Bragg and diffuse X-ray scattering provide a means of obtaining experimentally validated models of protein conformational ensembles. This paper shows that compared with a single periodic unit-cell model, the accuracy of simulating diffuse scattering is increased when the crystal is modeled as a periodic supercell consisting of a 2 × 2 × 2 layout of eight unit cells. The MD simulations capture the general dependence of correlations on the separation of atoms. There is substantial agreement between the simulated Bragg reflections and the crystal structure; there are local deviations, however, indicating both the limitation of using a single structure to model disordered regions of the protein and local deviations of the average structure away from the crystal structure. Although it was anticipated that a simulation of longer duration might be required to achieve maximal agreement of the diffuse scattering calculation with the data using the supercell model, only a microsecond is required, the same as for the unit cell. Rigid protein motions only account for a minority fraction of the variation in atom positions from the simulation. The results indicate that protein crystal dynamics may be dominated by internal motions rather than packing interactions, and that MD simulations can be combined with Bragg and diffuse X-ray scattering to model the protein conformational ensemble.

  16. Internal protein motions in molecular-dynamics simulations of Bragg and diffuse X-ray scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wall, Michael E.

    Molecular-dynamics (MD) simulations of Bragg and diffuse X-ray scattering provide a means of obtaining experimentally validated models of protein conformational ensembles. This paper shows that compared with a single periodic unit-cell model, the accuracy of simulating diffuse scattering is increased when the crystal is modeled as a periodic supercell consisting of a 2 × 2 × 2 layout of eight unit cells. The MD simulations capture the general dependence of correlations on the separation of atoms. There is substantial agreement between the simulated Bragg reflections and the crystal structure; there are local deviations, however, indicating both the limitation of using a single structuremore » to model disordered regions of the protein and local deviations of the average structure away from the crystal structure. Although it was anticipated that a simulation of longer duration might be required to achieve maximal agreement of the diffuse scattering calculation with the data using the supercell model, only a microsecond is required, the same as for the unit cell. Rigid protein motions only account for a minority fraction of the variation in atom positions from the simulation. The results indicate that protein crystal dynamics may be dominated by internal motions rather than packing interactions, and that MD simulations can be combined with Bragg and diffuse X-ray scattering to model the protein conformational ensemble.« less

  17. Internal protein motions in molecular-dynamics simulations of Bragg and diffuse X-ray scattering

    DOE PAGES

    Wall, Michael E.

    2018-01-25

    Molecular-dynamics (MD) simulations of Bragg and diffuse X-ray scattering provide a means of obtaining experimentally validated models of protein conformational ensembles. This paper shows that compared with a single periodic unit-cell model, the accuracy of simulating diffuse scattering is increased when the crystal is modeled as a periodic supercell consisting of a 2 × 2 × 2 layout of eight unit cells. The MD simulations capture the general dependence of correlations on the separation of atoms. There is substantial agreement between the simulated Bragg reflections and the crystal structure; there are local deviations, however, indicating both the limitation of using a single structuremore » to model disordered regions of the protein and local deviations of the average structure away from the crystal structure. Although it was anticipated that a simulation of longer duration might be required to achieve maximal agreement of the diffuse scattering calculation with the data using the supercell model, only a microsecond is required, the same as for the unit cell. Rigid protein motions only account for a minority fraction of the variation in atom positions from the simulation. The results indicate that protein crystal dynamics may be dominated by internal motions rather than packing interactions, and that MD simulations can be combined with Bragg and diffuse X-ray scattering to model the protein conformational ensemble.« less

  18.  X-RAYING THE DARK SIDE OF VENUS—SCATTER FROM VENUS’ MAGNETOTAIL?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Afshari, M.; Peres, G.; Petralia, A.

    We analyze significant X-ray, EUV, and UV emission coming from the dark side of Venus observed with Hinode /XRT and Solar Dynamics Observatory /Atmospheric Imaging Assembly ( SDO /AIA) during a transit across the solar disk that occurred in 2012. As a check we have analyzed an analogous Mercury transit that occurred in 2006. We have used the latest version of the Hinode /XRT point spread function to deconvolve Venus and Mercury X-ray images, to remove instrumental scattering. After deconvolution, the flux from Venus’ shadow remains significant while that of Mercury becomes negligible. Since stray light contamination affects the XRT Ti-poly filtermore » data we use, we performed the same analysis with XRT Al-mesh filter data, not affected by the light leak. Even the latter data show residual flux. We have also found significant EUV (304 Å, 193 Å, 335 Å) and UV (1700 Å) flux in Venus’ shadow, measured with SDO /AIA. The EUV emission from Venus’ dark side is reduced, but still significant, when deconvolution is applied. The light curves of the average flux of the shadow in the X-ray, EUV, and UV bands appear different as Venus crosses the solar disk, but in any of them the flux is, at any time, approximately proportional to the average flux in a ring surrounding Venus, and therefore proportional to that of the solar regions around Venus’ obscuring disk line of sight. The proportionality factor depends on the band. This phenomenon has no clear origin; we suggest that it may be due to scatter occurring in the very long magnetotail of Venus.« less

  19. Determination of line profiles on nano-structured surfaces using EUV and x-ray scattering

    NASA Astrophysics Data System (ADS)

    Soltwisch, Victor; Wernecke, Jan; Haase, Anton; Probst, Jürgen; Schoengen, Max; Krumrey, Michael; Scholze, Frank; Pomplun, Jan; Burger, Sven

    2014-09-01

    Non-imaging techniques like X-ray scattering are supposed to play an important role in the further development of CD metrology for the semiconductor industry. Grazing Incidence Small Angle X-ray Scattering (GISAXS) provides directly assessable information on structure roughness and long-range periodic perturbations. The disadvantage of the method is the large footprint of the X-ray beam on the sample due to the extremely shallow angle of incidence. This can be overcome by using wavelengths in the extreme ultraviolet (EUV) spectral range, EUV small angle scattering (EUVSAS), which allows for much steeper angles of incidence but preserves the range of momentum transfer that can be observed. Generally, the potentially higher momentum transfer at shorter wavelengths is counterbalanced by decreasing diffraction efficiency. This results in a practical limit of about 10 nm pitch for which it is possible to observe at least the +/- 1st diffraction orders with reasonable efficiency. At the Physikalisch-Technische Bundesanstalt (PTB), the available photon energy range extends from 50 eV up to 10 keV at two adjacent beamlines. PTB commissioned a new versatile Ellipso-Scatterometer which is capable of measuring 6" square substrates in a clean, hydrocarbon-free environment with full flexibility regarding the direction of the incident light polarization. The reconstruction of line profiles using a geometrical model with six free parameters, based on a finite element method (FEM) Maxwell solver and a particle swarm based least-squares optimization yielded consistent results for EUV-SAS and GISAXS. In this contribution we present scatterometry data for line gratings and consistent reconstruction results of the line geometry for EUV-SAS and GISAXS.

  20. Accurate Modeling of X-ray Extinction by Interstellar Grains

    NASA Astrophysics Data System (ADS)

    Hoffman, John; Draine, B. T.

    2016-02-01

    Interstellar abundance determinations from fits to X-ray absorption edges often rely on the incorrect assumption that scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must be taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. We present an open source Fortran suite, General Geometry Anomalous Diffraction Theory (GGADT), that calculates X-ray absorption, scattering, and differential scattering cross sections for grains of arbitrary geometry and composition.

  1. ACCURATE MODELING OF X-RAY EXTINCTION BY INTERSTELLAR GRAINS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hoffman, John; Draine, B. T., E-mail: jah5@astro.princeton.edu, E-mail: draine@astro.princeton.edu

    Interstellar abundance determinations from fits to X-ray absorption edges often rely on the incorrect assumption that scattering is insignificant and can be ignored. We show instead that scattering contributes significantly to the attenuation of X-rays for realistic dust grain size distributions and substantially modifies the spectrum near absorption edges of elements present in grains. The dust attenuation modules used in major X-ray spectral fitting programs do not take this into account. We show that the consequences of neglecting scattering on the determination of interstellar elemental abundances are modest; however, scattering (along with uncertainties in the grain size distribution) must bemore » taken into account when near-edge extinction fine structure is used to infer dust mineralogy. We advertise the benefits and accuracy of anomalous diffraction theory for both X-ray halo analysis and near edge absorption studies. We present an open source Fortran suite, General Geometry Anomalous Diffraction Theory (GGADT), that calculates X-ray absorption, scattering, and differential scattering cross sections for grains of arbitrary geometry and composition.« less

  2. Quantitative evaluation of bone-mineral density loss using X-ray coherent scattering

    NASA Astrophysics Data System (ADS)

    Barroso, Regina Cély; Oliveira, Luis Fernando; Castro, Carlos Roberto Ferreira; Lima, João Carlos; Braz, Delson; Lopes, Ricardo Tadeu; Droppa, Roosevel; Tromba, Giuliana; Mancini, Lucia; Zanini, Franco; Rigon, Luigi; Dreossi, Diego

    2007-08-01

    In this work, we intend to relate the mineral to non-mineral bone scattering intensity ratio with the bone-mineral density (BMD) reduction. In this way, EDXRD can be a novel technique to measure BMD loss in function of the mineral and non-mineral scattering intensity. The scattering profiles were obtained at Laboratório Nacional de Luz Síncrotron (LNLS) at the X-ray diffraction beamline XD2. A double-crystal Si(1 1 1) pre-monochromator, upstream of the beamline, was used to select a small energy bandwidth (Δ λ/ λ≈10 -4) at 11 keV. The sample holder has a circle depression in the center to contain a range of bone and fat mixture ratios. The mixture consists of powdered cortical bone and fat, which together simulate in vivo bone. The diffraction patterns were carried out with 0.5 mm slits after and behind of the sample holder. The data were collected in 0.05° increments every 0.5 s. EDXRD results show an indication of different bone densities may be distinguished which suggested that X-ray coherent scattering technique may have a role in monitoring changes in BMD via changes in the related scattering intensity of mineral and non-mineral bone. The main aim of the Synchrotron Radiation for MEdical Physics (SYRMEP) project at the ELETTRA is the investigation and the development of innovative techniques for medical imaging. The beamline provides, at a distance of about 23 m from the source, a monochromatic, laminar section X-ray beam with a maximum area of about 160×5 mm 2 at 20 keV. The monochromator, that covers the entire angular acceptance of the beamline, is based on a double-Si (1 1 1) crystal system working in Bragg configuration. A micrometric vertical and horizontal translation stage allows the positioning and scanning of the sample with respect to the stationary beam. In this case, the detector is kept stationary in front of the beam, while the object is rotated in discrete steps in front of it. At each rotation, a projection is acquired. A goniometric

  3. X-Ray Dust Scattering At Small Angles: The Complete Halo Around GX13+1

    NASA Technical Reports Server (NTRS)

    Smith, Randall K.

    2007-01-01

    The exquisite angular resolution available with Chandra should allow precision measurements of faint diffuse emission surrounding bright sources, such as the X-ray scattering halos created by interstellar dust. However, the ACIS CCDs suffer from pileup when observing bright sources, and this creates difficulties when trying to extract the scattered halo near the source. The initial study of the X-ray halo around GX13+1 using only the ACIS-I detector done by Smith, Edgar & Shafer (2002) suffered from a lack of sensitivity within 50" of the source, limiting what conclusions could be drawn. To address this problem, observations of GX13+1 were obtained with the Chandra HRC-I and simultaneously with the RXTE PCA. Combined with the existing ACIS-I data, this allowed measurements of the X-ray halo between 2-1000". After considering a range of dust models, each assumed to be smoothly distributed with or without a dense cloud along the line of sight, the results show that there is no evidence in this data for a dense cloud near the source, as suggested by Xiang et al. (2005). In addition, although no model leads to formally acceptable results, the Weingartner & Draine (2001) and all but one of the composite grain models from Zubko, Dwek & Arendt (2004) give particularly poor fits.

  4. X-ray radiation from nonlinear Thomson scattering of an intense femtosecond laser on relativistic electrons in a helium plasma.

    PubMed

    Ta Phuoc, K; Rousse, A; Pittman, M; Rousseau, J P; Malka, V; Fritzler, S; Umstadter, D; Hulin, D

    2003-11-07

    We have generated x-ray radiation from the nonlinear Thomson scattering of a 30 fs/1.5 J laser beam on plasma electrons. A collimated x-ray radiation with a broad continuous spectrum peaked at 0.15 keV with a significant tail up to 2 keV has been observed. These characteristics are found to depend strongly on the laser strength parameter a(0). This radiative process is dominant for a(0) greater than unity at which point the relativistic scattering of the laser light originates from MeV energy electrons inside the plasma.

  5. Experimental investigation of a HOPG crystal fan for x-ray fluorescence molecular imaging

    NASA Astrophysics Data System (ADS)

    Rosentreter, Tanja; Müller, Bernhard; Schlattl, Helmut; Hoeschen, Christoph

    2017-03-01

    Imaging x-ray fluorescence generally generates a conflict between the best image quality or highest sensitivity and lowest possible radiation dose. Consequently many experimental studies investigating the feasibility of this molecular imaging method, deal with either monochromatic x-ray sources that are not practical in clinical environment or accept high x-ray doses in order to maintain the advantage of high sensitivity and producing high quality images. In this work we present a x-ray fluorescence imaging setup using a HOPG crystal fan construction consisting of a Bragg reflecting analyzer array together with a scatter reducing radial collimator. This method allows for the use of polychromatic x-ray tubes that are in general easily accessible in contrast to monochromatic x-ray sources such as synchrotron facilities. Moreover this energy-selecting device minimizes the amount of Compton scattered photons while simultaneously increasing the fluorescence signal yield, thus significantly reducing the signal to noise ratio. The aim is to show the feasibility of this approach by measuring the Bragg reflected Kα fluorescence signal of an object containing an iodine solution using a large area detector with moderate energy resolution. Contemplating the anisotropic energy distribution of background scattered x-rays we compare the detection sensitivity, applying two different detector angular configurations. Our results show that even for large area detectors with limited energy resolution, iodine concentrations of 0.12 % can be detected. However, the potentially large scan times and therefore high radiation dose need to be decreased in further investigations.

  6. Thomson scattering laser-electron X-ray source for reduction of patient radiation dose in interventional coronary angiography

    NASA Astrophysics Data System (ADS)

    Artyukov, I. A.; Dyachkov, N. V.; Feshchenko, R. M.; Polunina, A. V.; Popov, N. L.; Shvedunov, V. I.; Vinogradov, A. V.

    2017-05-01

    It was medical applications that stimulated F. Carrol in the early 1990s to start the research of on relativistic Thomson scattering X-ray sources, as a part of the infrastructure of the future society. The possibility to use such a source in interventional cardiology is discussed in this paper. The replacement of X-ray tube by relativistic Thomson scattering Xray source is predicted to lower the patient radiation dose by a factor of 3 while image quality remains the same. The required general characteristics of accelerator and laser units are found. They can be reached by existing technology. A semiempirical method for simulation of medical and technical parameters of interventional coronary angiography systems is suggested.

  7. Measurement of carbon condensates using small-angle x-ray scattering during detonation of high explosives

    NASA Astrophysics Data System (ADS)

    Willey, T. M.; Bagge-Hansen, M.; Lauderbach, L.; Hodgin, R.; Hansen, D.; May, C.; van Buuren, T.; Dattelbaum, D. M.; Gustavsen, R. L.; Watkins, E. B.; Firestone, M. A.; Jensen, B. J.; Graber, T.; Bastea, S.; Fried, L.

    2017-01-01

    The lack of experimental validation for processes occurring at sub-micron length scales on time scales ranging from nanoseconds to microseconds hinders detonation model development. Particularly, quantification of late-time energy release requires measurement of carbon condensation kinetics behind detonation fronts. A new small-angle x-ray scattering (SAXS) endstation has been developed for use at The Dynamic Compression Sector to observe carbon condensation during detonation. The endstation and beamline demonstrate unprecedented fidelity; SAXS profiles can be acquired from single x-ray pulses, which in 24-bunch mode are about 80 ps in duration and arrive every 153.4 ns. This paper presents both the current temporal capabilities of this beamline, and the ability to distinguish different carbon condensate morphologies as they form behind detonation fronts. To demonstrate temporal capabilities, three shots acquired during detonation of hexanitrostilbene (HNS) are interleaved to show the evolution of the SAXS in about 50 ns steps. To show fidelity of the SAXS, the scattering from carbon condensates at several hundred nanoseconds varies with explosive: scattering from HNS is consistent with a complex morphology that we assert is associated with sp2 carbon., while Comp B scattering is consistent with soots containing three-dimensional diamond nanoparticles.

  8. Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments.

    PubMed

    Bras, Wim; Koizumi, Satoshi; Terrill, Nicholas J

    2014-11-01

    Small- and wide-angle X-ray scattering (SAXS, WAXS) are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments.

  9. Stoichiometry of Cd(S,Se) nanocrystals by anomalous small-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Ramos, Aline; Lyon, Olivier; Levelut, Claire

    1995-12-01

    In Cd(S,Se)-doped glasses the optical properties are strongly dependent on the size of the nanocrystals, but can be also largely modified by changes in the crystal stoichiometry; however, the information on both stoichiometry and size is difficult to obtain in crystals smaller than 10 nm. The intensity scattered at small angles is classically used to get information about nanoparticles sizes. Moreover the variation of amplitude of this intensity with the energy of the x ray—``the anomalous effect''—near the selenium edge is related to stoichiometry. Anomalous small-angle x-ray scattering has been used as a tentative method to get information about stoichiometry in nanocrystals with size lower than 10 nm. Experiments have been performed on samples treated for 2 days at temperatures in the range 540-650 °C. The samples treated at temperatures above 580 °C contain crystals with size larger than 4 nm. For all these samples the anomalous effect has nearly the same amplitude, and we found the stoichiometry x=0.4 for the CdSxSe1-x nanocrystals. This agrees with the previous results obtained by scanning electron microscopy and Raman spectroscopy. The results are also confirmed by measurements of the position of the optical absorption edge and by wide-angle x-ray scattering experiments. For the sample treated at 560 °C, the nanocrystal size is 3 nm and the stoichiometry x=0.6 is deduced from the anomalous effect. For samples treated at lower temperatures the anomalous effect is not observable, indicating an even lower selenium content in the nanocrystals (x≳0.7). We observed differences in the Se content of nanocrystals for different heat treatments of the same initial glass. These results may be very helpful to interpret the change in the optical properties when the temperature of the treatments decreases in the range 560-590 °C. In this temperature range, compositional effects seem to be of the same order of magnitude as the effects of the quantum confinement.

  10. X-ray echo spectroscopy (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Shvyd'ko, Yuri V.

    2016-09-01

    X-ray echo spectroscopy, a counterpart of neutron spin-echo, was recently introduced [1] to overcome limitations in spectral resolution and weak signals of the traditional inelastic x-ray scattering (IXS) probes. An image of a point-like x-ray source is defocused by a dispersing system comprised of asymmetrically cut specially arranged Bragg diffracting crystals. The defocused image is refocused into a point (echo) in a time-reversal dispersing system. If the defocused beam is inelastically scattered from a sample, the echo signal acquires a spatial distribution, which is a map of the inelastic scattering spectrum. The spectral resolution of the echo spectroscopy does not rely on the monochromaticity of the x-rays, ensuring strong signals along with a very high spectral resolution. Particular schemes of x-ray echo spectrometers for 0.1-meV and 0.02-meV ultra-high-resolution IXS applications (resolving power > 10^8) with broadband 5-13 meV dispersing systems will be presented featuring more than 1000-fold signal enhancement. The technique is general, applicable in different photon frequency domains. [1.] Yu. Shvyd'ko, Phys. Rev. Lett. 116, accepted (2016), arXiv:1511.01526.

  11. Acoustic phonons in chrysotile asbestos probed by high-resolution inelastic x-ray scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mamontov, Eugene; Vakhrushev, S. B.; Kumzerov, Yu. A,

    Acoustic phonons in an individual, oriented fiber of chrysotile asbestos (chemical formula Mg{sub 3}Si{sub 2}O{sub 5}(OH){sub 4}) were observed at room temperature in the inelastic x-ray measurement with a very high (meV) resolution. The x-ray scattering vector was aligned along [1 0 0] direction of the reciprocal lattice, nearly parallel to the long axis of the fiber. The latter coincides with [1 0 0] direction of the direct lattice and the axes of the nano-channels. The data were analyzed using a damped harmonic oscillator model. Analysis of the phonon dispersion in the first Brillouin zone yielded the longitudinal sound velocitymore » of (9200 {+-} 600) m/s.« less

  12. Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Devereaux, T. P.; Shvaika, A. M.; Wu, K.

    The coupling between lattice and charge degrees of freedom in condensed matter materials is ubiquitous and can often result in interesting properties and ordered phases, including conventional superconductivity, charge-density wave order, and metal-insulator transitions. Angle-resolved photoemission spectroscopy and both neutron and nonresonant x-ray scattering serve as effective probes for determining the behavior of appropriate, individual degrees of freedom—the electronic structure and lattice excitation, or phonon dispersion, respectively. However, each provides less direct information about the mutual coupling between the degrees of freedom, usually through self-energy effects, which tend to renormalize and broaden spectral features precisely where the coupling is strong,more » impacting one’s ability to quantitatively characterize the coupling. Here, we demonstrate that resonant inelastic x-ray scattering, or RIXS, can be an effective tool to directly determine the relative strength and momentum dependence of the electron-phonon coupling in condensed matter systems. Using a diagrammatic approach for an eight-band model of copper oxides, we study the contributions from the lowest-order diagrams to the full RIXS intensity for a realistic scattering geometry, accounting for matrix element effects in the scattering cross section, as well as the momentum dependence of the electron-phonon coupling vertex. A detailed examination of these maps offers a unique perspective into the characteristics of electron-phonon coupling, which complements both neutron and nonresonant x-ray scattering, as well as Raman and infrared conductivity.« less

  13. Directly Characterizing the Relative Strength and Momentum Dependence of Electron-Phonon Coupling Using Resonant Inelastic X-Ray Scattering

    DOE PAGES

    Devereaux, T. P.; Shvaika, A. M.; Wu, K.; ...

    2016-10-25

    The coupling between lattice and charge degrees of freedom in condensed matter materials is ubiquitous and can often result in interesting properties and ordered phases, including conventional superconductivity, charge-density wave order, and metal-insulator transitions. Angle-resolved photoemission spectroscopy and both neutron and nonresonant x-ray scattering serve as effective probes for determining the behavior of appropriate, individual degrees of freedom—the electronic structure and lattice excitation, or phonon dispersion, respectively. However, each provides less direct information about the mutual coupling between the degrees of freedom, usually through self-energy effects, which tend to renormalize and broaden spectral features precisely where the coupling is strong,more » impacting one’s ability to quantitatively characterize the coupling. Here, we demonstrate that resonant inelastic x-ray scattering, or RIXS, can be an effective tool to directly determine the relative strength and momentum dependence of the electron-phonon coupling in condensed matter systems. Using a diagrammatic approach for an eight-band model of copper oxides, we study the contributions from the lowest-order diagrams to the full RIXS intensity for a realistic scattering geometry, accounting for matrix element effects in the scattering cross section, as well as the momentum dependence of the electron-phonon coupling vertex. A detailed examination of these maps offers a unique perspective into the characteristics of electron-phonon coupling, which complements both neutron and nonresonant x-ray scattering, as well as Raman and infrared conductivity.« less

  14. Structural evaluation of an amyloid fibril model using small-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Dahal, Eshan; Choi, Mina; Alam, Nadia; Bhirde, Ashwinkumar A.; Beaucage, Serge L.; Badano, Aldo

    2017-08-01

    Amyloid fibrils are highly structured protein aggregates associated with a wide range of diseases including Alzheimer’s and Parkinson’s. We report a structural investigation of an amyloid fibril model prepared from a commonly used plasma protein (bovine serum albumin (BSA)) using small-angle x-ray scattering (SAXS) technique. As a reference, the size estimates from SAXS are compared to dynamic light scattering (DLS) data and the presence of amyloid-like fibrils is confirmed using Congo red absorbance assay. Our SAXS results consistently show the structural transformation of BSA from spheroid to rod-like elongated structures during the fibril formation process. We observe the elongation of fibrils over two months with fibril length growing from 35.9  ±  3.0 nm to 51.5  ±  2.1 nm. Structurally metastable fibrils with distinct SAXS profiles have been identified. As proof of concept, we demonstrate the use of such distinct SAXS profiles to detect fibrils in the mixture solutions of two species by estimating their volume fractions. This easily detectable and well-characterized amyloid fibril model from BSA can be readily used as a control or standard reference to further investigate SAXS applications in the detection of structurally diverse amyloid fibrils associated with protein aggregation diseases.

  15. Erratum: Creation of X-Ray Transparency of Matter by Stimulated Elastic Forward Scattering [Phys. Rev. Lett. 115 , 107402 (2015)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stöhr, J.; Scherz, A.

    X-ray absorption by matter has long been described by the famous Beer-Lambert law. Here we show how this fundamental law needs to be modified for high-intensity coherent x-ray pulses, now available at x-ray free electron lasers, due to the onset of stimulated elastic forward scattering. We present an analytical expression for the modified polarization-dependent Beer-Lambert law for the case of resonant core-to-valence electronic transitions and incident transform limited x-ray pulses. Upon transmission through a solid, the absorption and dichroic contrasts are found to vanish with increasing x-ray intensity, with the stimulation threshold lowered by orders of magnitude through a super-radiativemore » coherent effect. Our results have broad implications for the study of matter with x-ray lasers.« less

  16. The atomic scale structure of CXV carbon: wide-angle x-ray scattering and modeling studies.

    PubMed

    Hawelek, L; Brodka, A; Dore, J C; Honkimaki, V; Burian, A

    2013-11-13

    The disordered structure of commercially available CXV activated carbon produced from finely powdered wood-based carbon has been studied using the wide-angle x-ray scattering technique, molecular dynamics and density functional theory simulations. The x-ray scattering data has been converted to the real space representation in the form of the pair correlation function via the Fourier transform. Geometry optimizations using classical molecular dynamics based on the reactive empirical bond order potential and density functional theory at the B3LYP/6-31g* level have been performed to generate nanoscale models of CXV carbon consistent with the experimental data. The final model of the structure comprises four chain-like and buckled graphitic layers containing a small percentage of four-fold coordinated atoms (sp(3) defects) in each layer. The presence of non-hexagonal rings in the atomic arrangement has been also considered.

  17. Physics and Computational Methods for X-ray Scatter Estimation and Correction in Cone-Beam Computed Tomography

    NASA Astrophysics Data System (ADS)

    Bootsma, Gregory J.

    X-ray scatter in cone-beam computed tomography (CBCT) is known to reduce image quality by introducing image artifacts, reducing contrast, and limiting computed tomography (CT) number accuracy. The extent of the effect of x-ray scatter on CBCT image quality is determined by the shape and magnitude of the scatter distribution in the projections. A method to allay the effects of scatter is imperative to enable application of CBCT to solve a wider domain of clinical problems. The work contained herein proposes such a method. A characterization of the scatter distribution through the use of a validated Monte Carlo (MC) model is carried out. The effects of imaging parameters and compensators on the scatter distribution are investigated. The spectral frequency components of the scatter distribution in CBCT projection sets are analyzed using Fourier analysis and found to reside predominately in the low frequency domain. The exact frequency extents of the scatter distribution are explored for different imaging configurations and patient geometries. Based on the Fourier analysis it is hypothesized the scatter distribution can be represented by a finite sum of sine and cosine functions. The fitting of MC scatter distribution estimates enables the reduction of the MC computation time by diminishing the number of photon tracks required by over three orders of magnitude. The fitting method is incorporated into a novel scatter correction method using an algorithm that simultaneously combines multiple MC scatter simulations. Running concurrent MC simulations while simultaneously fitting the results allows for the physical accuracy and flexibility of MC methods to be maintained while enhancing the overall efficiency. CBCT projection set scatter estimates, using the algorithm, are computed on the order of 1--2 minutes instead of hours or days. Resulting scatter corrected reconstructions show a reduction in artifacts and improvement in tissue contrast and voxel value accuracy.

  18. X-ray Raman scattering from molecules and solids in the framework of the Mahan-Nozières-De Dominicis model

    NASA Astrophysics Data System (ADS)

    Privalov, Timofei; Gel'mukhanov, Faris; Ågren, Hans

    2001-10-01

    We have developed a formulation of resonant x-ray Raman scattering of molecules and solids based on the Mahan-Nozières-De Dominicis model. A key step in the formulation is given by a reduction of the Keldysh-Dyson equations for the Green's function to a set of linear algebraic equations. This gave way for a tractable scheme that can be used to analyze the resonant x-ray scattering in the whole time domain. The formalism is used to investigate the role of core-hole relaxation, interference, band filling, detuning, and size of the scattering target. Numerical applications are performed with a one-dimensional tight-binding model.

  19. Compton spectra of atoms at high x-ray intensity

    NASA Astrophysics Data System (ADS)

    Son, Sang-Kil; Geffert, Otfried; Santra, Robin

    2017-03-01

    Compton scattering is the nonresonant inelastic scattering of an x-ray photon by an electron and has been used to probe the electron momentum distribution in gas-phase and condensed-matter samples. In the low x-ray intensity regime, Compton scattering from atoms dominantly comes from bound electrons in neutral atoms, neglecting contributions from bound electrons in ions and free (ionized) electrons. In contrast, in the high x-ray intensity regime, the sample experiences severe ionization via x-ray multiphoton multiple ionization dynamics. Thus, it becomes necessary to take into account all the contributions to the Compton scattering signal when atoms are exposed to high-intensity x-ray pulses provided by x-ray free-electron lasers (XFELs). In this paper, we investigate the Compton spectra of atoms at high x-ray intensity, using an extension of the integrated x-ray atomic physics toolkit, xatom. As the x-ray fluence increases, there is a significant contribution from ionized electrons to the Compton spectra, which gives rise to strong deviations from the Compton spectra of neutral atoms. The present study provides not only understanding of the fundamental XFEL-matter interaction but also crucial information for single-particle imaging experiments, where Compton scattering is no longer negligible. , which features invited work from the best early-career researchers working within the scope of J. Phys. B. This project is part of the Journal of Physics series’ 50th anniversary celebrations in 2017. Sang-Kil Son was selected by the Editorial Board of J. Phys. B as an Emerging Leader.

  20. X-ray scattering study of pyrochlore iridates: Crystal structure, electronic, and magnetic excitations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Clancy, J. P.; Gretarsson, H.; Lee, E. K. H.

    2016-07-06

    We have investigated the structural, electronic, and magnetic properties of the pyrochlore iridates Eu 2Ir 2O 7 and Pr 2Ir 2O 7 using a combination of resonant elastic x-ray scattering, x-ray powder diffraction, and resonant inelastic x-ray scattering (RIXS). The structural parameters of Eu 2Ir 2O 7 have been examined as a function of temperature and applied pressure, with a particular emphasis on regions of the phase diagram where electronic and magnetic phase transitions have been reported. We find no evidence of crystal symmetry change over the range of temperatures (~6 to 300 K) and pressures (~0.1 to 17 GPa)more » studied. We have also investigated the electronic and magnetic excitations in single-crystal samples of Eu 2Ir 2O 7 and Pr 2Ir 2O 7 using high-resolution Ir L- 3-edge RIXS. In spite of very different ground state properties, we find that these materials exhibit qualitatively similar excitation spectra, with crystal field excitations at ~3-5 eV, spin-orbit excitations at ~ 0.5-1 eV, and broad low-lying excitations below ~0.15 eV. In single-crystal samples of "Eu-rich" Eu 2Ir 2O 7 (found to possess an actual stoichiometry of Eu 2.18Ir 1.82O 7.06) we observe highly damped magnetic excitations at ~45 meV, which display significant momentum dependence. Here, we compare these results with recent dynamical structure factor calculations« less

  1. Automated sample-changing robot for solution scattering experiments at the EMBL Hamburg SAXS station X33

    PubMed Central

    Round, A. R.; Franke, D.; Moritz, S.; Huchler, R.; Fritsche, M.; Malthan, D.; Klaering, R.; Svergun, D. I.; Roessle, M.

    2008-01-01

    There is a rapidly increasing interest in the use of synchrotron small-angle X-ray scattering (SAXS) for large-scale studies of biological macromolecules in solution, and this requires an adequate means of automating the experiment. A prototype has been developed of an automated sample changer for solution SAXS, where the solutions are kept in thermostatically controlled well plates allowing for operation with up to 192 samples. The measuring protocol involves controlled loading of protein solutions and matching buffers, followed by cleaning and drying of the cell between measurements. The system was installed and tested at the X33 beamline of the EMBL, at the storage ring DORIS-III (DESY, Hamburg), where it was used by over 50 external groups during 2007. At X33, a throughput of approximately 12 samples per hour, with a failure rate of sample loading of less than 0.5%, was observed. The feedback from users indicates that the ease of use and reliability of the user operation at the beamline were greatly improved compared with the manual filling mode. The changer is controlled by a client–server-based network protocol, locally and remotely. During the testing phase, the changer was operated in an attended mode to assess its reliability and convenience. Full integration with the beamline control software, allowing for automated data collection of all samples loaded into the machine with remote control from the user, is presently being implemented. The approach reported is not limited to synchrotron-based SAXS but can also be used on laboratory and neutron sources. PMID:25484841

  2. X-ray Survey of Centaurus A.

    PubMed

    Byram, E T; Chubb, T A; Friedman, H

    1970-07-24

    An x-ray survey of Centaurus A has given marginal evidence of its x-ray flux. If taken as an upper limit on inverse Compton x-rays generated by scattering interactions between relativistic electrons and cosmological background photons, the observation implies an upper limit of close to 3 degrees K for the background radiation temperature.

  3. Conformational variability of the stationary phase survival protein E from Xylella fastidiosa revealed by X-ray crystallography, small-angle X-ray scattering studies, and normal mode analysis.

    PubMed

    Machado, Agnes Thiane Pereira; Fonseca, Emanuella Maria Barreto; Reis, Marcelo Augusto Dos; Saraiva, Antonio Marcos; Santos, Clelton Aparecido Dos; de Toledo, Marcelo Augusto Szymanski; Polikarpov, Igor; de Souza, Anete Pereira; Aparicio, Ricardo; Iulek, Jorge

    2017-10-01

    Xylella fastidiosa is a xylem-limited bacterium that infects a wide variety of plants. Stationary phase survival protein E is classified as a nucleotidase, which is expressed when bacterial cells are in the stationary growth phase and subjected to environmental stresses. Here, we report four refined X-ray structures of this protein from X. fastidiosa in four different crystal forms in the presence and/or absence of the substrate 3'-AMP. In all chains, the conserved loop verified in family members assumes a closed conformation in either condition. Therefore, the enzymatic mechanism for the target protein might be different of its homologs. Two crystal forms exhibit two monomers whereas the other two show four monomers in the asymmetric unit. While the biological unit has been characterized as a tetramer, differences of their sizes and symmetry are remarkable. Four conformers identified by Small-Angle X-ray Scattering (SAXS) in a ligand-free solution are related to the low frequency normal modes of the crystallographic structures associated with rigid body-like protomer arrangements responsible for the longitudinal and symmetric adjustments between tetramers. When the substrate is present in solution, only two conformers are selected. The most prominent conformer for each case is associated to a normal mode able to elongate the protein by moving apart two dimers. To our knowledge, this work was the first investigation based on the normal modes that analyzed the quaternary structure variability for an enzyme of the SurE family followed by crystallography and SAXS validation. The combined results raise new directions to study allosteric features of XfSurE protein. © 2017 Wiley Periodicals, Inc.

  4. Probing molecular dynamics in solution with x-ray valence-to-core spectroscopy

    NASA Astrophysics Data System (ADS)

    Doumy, Gilles; March, Anne Marie; Tu, Ming-Feng; Al Haddad, Andre; Southworth, Stephen; Young, Linda; Walko, Donald; Bostedt, Christoph

    2017-04-01

    Hard X-ray spectroscopies are powerful tools for probing the electronic and geometric structure of molecules in complex or disordered systems and have been particularly useful for studying molecules in the solution phase. They are element specific, sensitive to the electronic structure and the local arrangements of surrounding atoms of the element being selectively probed. When combined in a pump-probe scheme with ultrafast lasers, X-ray spectroscopies can be used to track the evolution of structural changes that occur after photoexcitation. Efficient use of hard x-ray radiation coming from high brilliance synchrotrons and upcoming high repetition rate X-ray Free Electron Lasers requires MHz repetition rate lasers and data acquisition systems. High information content Valence-to-Core x-ray emission is directly sensitive to the molecular orbitals involved in photochemistry. We report on recent progress towards fully enabling this photon-hungry technique for the study of time-resolved molecular dynamics, including efficient detection and use of polychromatic x-ray micro-probe at the Advanced Photon Source. Work was supported by the U.S. Department of Energy, Office of Science, Chemical Sciences, Geosciences, and Biosciences Division.

  5. Soft x-ray scattering facility at the Advanced Light Source with real-time data processing and analysis

    NASA Astrophysics Data System (ADS)

    Gann, E.; Young, A. T.; Collins, B. A.; Yan, H.; Nasiatka, J.; Padmore, H. A.; Ade, H.; Hexemer, A.; Wang, C.

    2012-04-01

    We present the development and characterization of a dedicated resonant soft x-ray scattering facility. Capable of operation over a wide energy range, the beamline and endstation are primarily used for scattering from soft matter systems around the carbon K-edge (˜285 eV). We describe the specialized design of the instrument and characteristics of the beamline. Operational characteristics of immediate interest to users such as polarization control, degree of higher harmonic spectral contamination, and detector noise are delineated. Of special interest is the development of a higher harmonic rejection system that improves the spectral purity of the x-ray beam. Special software and a user-friendly interface have been implemented to allow real-time data processing and preliminary data analysis simultaneous with data acquisition.

  6. Beyond simple small-angle X-ray scattering: developments in online complementary techniques and sample environments

    PubMed Central

    Bras, Wim; Koizumi, Satoshi; Terrill, Nicholas J

    2014-01-01

    Small- and wide-angle X-ray scattering (SAXS, WAXS) are standard tools in materials research. The simultaneous measurement of SAXS and WAXS data in time-resolved studies has gained popularity due to the complementary information obtained. Furthermore, the combination of these data with non X-ray based techniques, via either simultaneous or independent measurements, has advanced understanding of the driving forces that lead to the structures and morphologies of materials, which in turn give rise to their properties. The simultaneous measurement of different data regimes and types, using either X-rays or neutrons, and the desire to control parameters that initiate and control structural changes have led to greater demands on sample environments. Examples of developments in technique combinations and sample environment design are discussed, together with a brief speculation about promising future developments. PMID:25485128

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

    NASA Astrophysics Data System (ADS)

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

    2013-03-01

    Ultra-small-angle X-ray scattering (USAXS) can probe microstructures over the nanometer-to-micrometer scale range. Through use of a small instrument entrance slit, X-ray photon correlation spectroscopy (XPCS) exploits the partial coherence of an X-ray synchrotron undulator beam to provide unprecedented sensitivity to the dynamics of microstructural change. In USAXS/XPCS studies, the dynamics of local structures in a scale range of 100 nm to 1000 nm can be related to an overall hierarchical microstructure extending from 1 nm to more than 1000 nm. Using a point-detection scintillator mode, the equilibrium dynamics at ambient temperature of small particles (which move more slowly than nanoparticles) in aqueous suspension have been quantified directly for the first time. Using a USAXS-XPCS scanning mode for non-equilibrium dynamics incipient processes within dental composites have been elucidated, prior to effects becoming detectable using any other technique. Use of the Advanced Photon Source, an Office of Science User Facility operated for the United States Department of Energy (U.S. DOE) Office of Science by Argonne National Laboratory, was supported by the U.S. DOE under Contract No. DE-AC02-06CH11357.

  8. Structural dissection of human metapneumovirus phosphoprotein using small angle x-ray scattering.

    PubMed

    Renner, Max; Paesen, Guido C; Grison, Claire M; Granier, Sébastien; Grimes, Jonathan M; Leyrat, Cédric

    2017-11-01

    The phosphoprotein (P) is the main and essential cofactor of the RNA polymerase (L) of non-segmented, negative-strand RNA viruses. P positions the viral polymerase onto its nucleoprotein-RNA template and acts as a chaperone of the nucleoprotein (N), thereby preventing nonspecific encapsidation of cellular RNAs. The phosphoprotein of human metapneumovirus (HMPV) forms homotetramers composed of a stable oligomerization domain (P core ) flanked by large intrinsically disordered regions (IDRs). Here we combined x-ray crystallography of P core with small angle x-ray scattering (SAXS)-based ensemble modeling of the full-length P protein and several of its fragments to provide a structural description of P that captures its dynamic character, and highlights the presence of varyingly stable structural elements within the IDRs. We discuss the implications of the structural properties of HMPV P for the assembly and functioning of the viral transcription/replication machinery.

  9. Fluorescent x-ray computed tomography to visualize specific material distribution

    NASA Astrophysics Data System (ADS)

    Takeda, Tohoru; Yuasa, Tetsuya; Hoshino, Atsunori; Akiba, Masahiro; Uchida, Akira; Kazama, Masahiro; Hyodo, Kazuyuki; Dilmanian, F. Avraham; Akatsuka, Takao; Itai, Yuji

    1997-10-01

    Fluorescent x-ray computed tomography (FXCT) is being developed to detect non-radioactive contrast materials in living specimens. The FXCT systems consists of a silicon channel cut monochromator, an x-ray slit and a collimator for detection, a scanning table for the target organ and an x-ray detector for fluorescent x-ray and transmission x-ray. To reduce Compton scattering overlapped on the K(alpha) line, incident monochromatic x-ray was set at 37 keV. At 37 keV Monte Carlo simulation showed almost complete separation between Compton scattering and the K(alpha) line. Actual experiments revealed small contamination of Compton scattering on the K(alpha) line. A clear FXCT image of a phantom was obtained. Using this system the minimal detectable dose of iodine was 30 ng in a volume of 1 mm3, and a linear relationship was demonstrated between photon counts of fluorescent x-rays and the concentration of iodine contrast material. The use of high incident x-ray energy allows an increase in the signal to noise ratio by reducing the Compton scattering on the K(alpha) line.

  10. TOPICAL REVIEW: Human soft tissue analysis using x-ray or gamma-ray techniques

    NASA Astrophysics Data System (ADS)

    Theodorakou, C.; Farquharson, M. J.

    2008-06-01

    This topical review is intended to describe the x-ray techniques used for human soft tissue analysis. X-ray techniques have been applied to human soft tissue characterization and interesting results have been presented over the last few decades. The motivation behind such studies is to provide improved patient outcome by using the data obtained to better understand a disease process and improve diagnosis. An overview of theoretical background as well as a complete set of references is presented. For each study, a brief summary of the methodology and results is given. The x-ray techniques include x-ray diffraction, x-ray fluorescence, Compton scattering, Compton to coherent scattering ratio and attenuation measurements. The soft tissues that have been classified using x-rays or gamma rays include brain, breast, colon, fat, kidney, liver, lung, muscle, prostate, skin, thyroid and uterus.

  11. Epp: A C++ EGSnrc user code for x-ray imaging and scattering simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lippuner, Jonas; Elbakri, Idris A.; Cui Congwu

    2011-03-15

    Purpose: Easy particle propagation (Epp) is a user code for the EGSnrc code package based on the C++ class library egspp. A main feature of egspp (and Epp) is the ability to use analytical objects to construct simulation geometries. The authors developed Epp to facilitate the simulation of x-ray imaging geometries, especially in the case of scatter studies. While direct use of egspp requires knowledge of C++, Epp requires no programming experience. Methods: Epp's features include calculation of dose deposited in a voxelized phantom and photon propagation to a user-defined imaging plane. Projection images of primary, single Rayleigh scattered, singlemore » Compton scattered, and multiple scattered photons may be generated. Epp input files can be nested, allowing for the construction of complex simulation geometries from more basic components. To demonstrate the imaging features of Epp, the authors simulate 38 keV x rays from a point source propagating through a water cylinder 12 cm in diameter, using both analytical and voxelized representations of the cylinder. The simulation generates projection images of primary and scattered photons at a user-defined imaging plane. The authors also simulate dose scoring in the voxelized version of the phantom in both Epp and DOSXYZnrc and examine the accuracy of Epp using the Kawrakow-Fippel test. Results: The results of the imaging simulations with Epp using voxelized and analytical descriptions of the water cylinder agree within 1%. The results of the Kawrakow-Fippel test suggest good agreement between Epp and DOSXYZnrc. Conclusions: Epp provides the user with useful features, including the ability to build complex geometries from simpler ones and the ability to generate images of scattered and primary photons. There is no inherent computational time saving arising from Epp, except for those arising from egspp's ability to use analytical representations of simulation geometries. Epp agrees with DOSXYZnrc in dose calculation

  12. Radiation damage in polymer films from grazing-incidence X-ray scattering measurements

    DOE PAGES

    Vaselabadi, Saeed Ahmadi; Shakarisaz, David; Ruchhoeft, Paul; ...

    2016-02-16

    Grazing-incidence X-ray scattering (GIXS) is widely used to analyze the crystallinity and nanoscale structure in thin polymer films. However, ionizing radiation will generate free radicals that initiate cross-linking and/or chain scission, and structural damage will impact the ordering kinetics, thermodynamics, and crystallinity in many polymers. We report a simple methodology to screen for beam damage that is based on lithographic principles: films are exposed to patterns of x-ray radiation, and changes in polymer structure are revealed by immersing the film in a solvent that dissolves the shortest chains. The experiments are implemented with high throughput using the standard beam linemore » instrumentation and a typical GIXS configuration. The extent of damage (at a fixed radiation dose) depends on a range of intrinsic material properties and experimental variables, including the polymer chemistry and molecular weight, exposure environment, film thickness, and angle of incidence. The solubility switch for common polymers is detected within 10-60 sec at ambient temperature, and we verified that this first indication of damage corresponds with the onset of network formation in glassy polystyrene and a loss of crystallinity in polyalkylthiophenes. Therefore, grazing-incidence x-ray patterning offers an efficient approach to determine the appropriate data acquisition times for any GIXS experiment.« less

  13. Scatter correction method for x-ray CT using primary modulation: Phantom studies

    PubMed Central

    Gao, Hewei; Fahrig, Rebecca; Bennett, N. Robert; Sun, Mingshan; Star-Lack, Josh; Zhu, Lei

    2010-01-01

    Purpose: Scatter correction is a major challenge in x-ray imaging using large area detectors. Recently, the authors proposed a promising scatter correction method for x-ray computed tomography (CT) using primary modulation. Proof of concept was previously illustrated by Monte Carlo simulations and physical experiments on a small phantom with a simple geometry. In this work, the authors provide a quantitative evaluation of the primary modulation technique and demonstrate its performance in applications where scatter correction is more challenging. Methods: The authors first analyze the potential errors of the estimated scatter in the primary modulation method. On two tabletop CT systems, the method is investigated using three phantoms: A Catphan©600 phantom, an anthropomorphic chest phantom, and the Catphan©600 phantom with two annuli. Two different primary modulators are also designed to show the impact of the modulator parameters on the scatter correction efficiency. The first is an aluminum modulator with a weak modulation and a low modulation frequency, and the second is a copper modulator with a strong modulation and a high modulation frequency. Results: On the Catphan©600 phantom in the first study, the method reduces the error of the CT number in the selected regions of interest (ROIs) from 371.4 to 21.9 Hounsfield units (HU); the contrast to noise ratio also increases from 10.9 to 19.2. On the anthropomorphic chest phantom in the second study, which represents a more difficult case due to the high scatter signals and object heterogeneity, the method reduces the error of the CT number from 327 to 19 HU in the selected ROIs and from 31.4% to 5.7% on the overall average. The third study is to investigate the impact of object size on the efficiency of our method. The scatter-to-primary ratio estimation error on the Catphan©600 phantom without any annulus (20 cm in diameter) is at the level of 0.04, it rises to 0.07 and 0.1 on the phantom with an elliptical

  14. Combining X-ray and neutron crystallography with spectroscopy.

    PubMed

    Kwon, Hanna; Smith, Oliver; Raven, Emma Lloyd; Moody, Peter C E

    2017-02-01

    X-ray protein crystallography has, through the determination of the three-dimensional structures of enzymes and their complexes, been essential to the understanding of biological chemistry. However, as X-rays are scattered by electrons, the technique has difficulty locating the presence and position of H atoms (and cannot locate H + ions), knowledge of which is often crucially important for the understanding of enzyme mechanism. Furthermore, X-ray irradiation, through photoelectronic effects, will perturb the redox state in the crystal. By using single-crystal spectrophotometry, reactions taking place in the crystal can be monitored, either to trap intermediates or follow photoreduction during X-ray data collection. By using neutron crystallography, the positions of H atoms can be located, as it is the nuclei rather than the electrons that scatter neutrons, and the scattering length is not determined by the atomic number. Combining the two techniques allows much greater insight into both reaction mechanism and X-ray-induced photoreduction.

  15. Improving x-ray fluorescence signal for benchtop polychromatic cone-beam x-ray fluorescence computed tomography by incident x-ray spectrum optimization: A Monte Carlo study

    PubMed Central

    Manohar, Nivedh; Jones, Bernard L.; Cho, Sang Hyun

    2014-01-01

    Purpose: To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). Methods: A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Results: Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the

  16. Improving x-ray fluorescence signal for benchtop polychromatic cone-beam x-ray fluorescence computed tomography by incident x-ray spectrum optimization: a Monte Carlo study.

    PubMed

    Manohar, Nivedh; Jones, Bernard L; Cho, Sang Hyun

    2014-10-01

    To develop an accurate and comprehensive Monte Carlo (MC) model of an experimental benchtop polychromatic cone-beam x-ray fluorescence computed tomography (XFCT) setup and apply this MC model to optimize incident x-ray spectrum for improving production/detection of x-ray fluorescence photons from gold nanoparticles (GNPs). A detailed MC model, based on an experimental XFCT system, was created using the Monte Carlo N-Particle (MCNP) transport code. The model was validated by comparing MC results including x-ray fluorescence (XRF) and scatter photon spectra with measured data obtained under identical conditions using 105 kVp cone-beam x-rays filtered by either 1 mm of lead (Pb) or 0.9 mm of tin (Sn). After validation, the model was used to investigate the effects of additional filtration of the incident beam with Pb and Sn. Supplementary incident x-ray spectra, representing heavier filtration (Pb: 2 and 3 mm; Sn: 1, 2, and 3 mm) were computationally generated and used with the model to obtain XRF/scatter spectra. Quasimonochromatic incident x-ray spectra (81, 85, 90, 95, and 100 keV with 10 keV full width at half maximum) were also investigated to determine the ideal energy for distinguishing gold XRF signal from the scatter background. Fluorescence signal-to-dose ratio (FSDR) and fluorescence-normalized scan time (FNST) were used as metrics to assess results. Calculated XRF/scatter spectra for 1-mm Pb and 0.9-mm Sn filters matched (r ≥ 0.996) experimental measurements. Calculated spectra representing additional filtration for both filter materials showed that the spectral hardening improved the FSDR at the expense of requiring a much longer FNST. In general, using Sn instead of Pb, at a given filter thickness, allowed an increase of up to 20% in FSDR, more prominent gold XRF peaks, and up to an order of magnitude decrease in FNST. Simulations using quasimonochromatic spectra suggested that increasing source x-ray energy, in the investigated range of 81-100 ke

  17. Dissipative quantum hydrodynamics model of x-ray Thomson scattering in dense plasmas

    NASA Astrophysics Data System (ADS)

    Diaw, Abdourahmane; Murillo, Michael

    2017-10-01

    X-ray Thomson scattering (XRTS) provides detailed diagnostic information about dense plasma experiments. The inferences made rely on an accurate model for the form factor, which is typically expressed in terms of a well-known response function. Here, we develop an alternate approach based on quantum hydrodynamics using a viscous form of dynamical density functional theory. This approach is shown to include the equation of state self-consistently, including sum rules, as well as irreversibility arising from collisions. This framework is used to generate a model for the scattering spectrum, and it offers an avenue for measuring hydrodynamic properties, such as transport coefficients, using XRTS. This work was supported by the Air Force Office of Scientific Research (Grant No. FA9550-12-1-0344).

  18. SOLEIL shining on the solution-state structure of biomacromolecules by synchrotron X-ray footprinting at the Metrology beamline.

    PubMed

    Baud, A; Aymé, L; Gonnet, F; Salard, I; Gohon, Y; Jolivet, P; Brodolin, K; Da Silva, P; Giuliani, A; Sclavi, B; Chardot, T; Mercère, P; Roblin, P; Daniel, R

    2017-05-01

    Synchrotron X-ray footprinting complements the techniques commonly used to define the structure of molecules such as crystallography, small-angle X-ray scattering and nuclear magnetic resonance. It is remarkably useful in probing the structure and interactions of proteins with lipids, nucleic acids or with other proteins in solution, often better reflecting the in vivo state dynamics. To date, most X-ray footprinting studies have been carried out at the National Synchrotron Light Source, USA, and at the European Synchrotron Radiation Facility in Grenoble, France. This work presents X-ray footprinting of biomolecules performed for the first time at the X-ray Metrology beamline at the SOLEIL synchrotron radiation source. The installation at this beamline of a stopped-flow apparatus for sample delivery, an irradiation capillary and an automatic sample collector enabled the X-ray footprinting study of the structure of the soluble protein factor H (FH) from the human complement system as well as of the lipid-associated hydrophobic protein S3 oleosin from plant seed. Mass spectrometry analysis showed that the structural integrity of both proteins was not affected by the short exposition to the oxygen radicals produced during the irradiation. Irradiated molecules were subsequently analysed using high-resolution mass spectrometry to identify and locate oxidized amino acids. Moreover, the analyses of FH in its free state and in complex with complement C3b protein have allowed us to create a map of reactive solvent-exposed residues on the surface of FH and to observe the changes in oxidation of FH residues upon C3b binding. Studies of the solvent accessibility of the S3 oleosin show that X-ray footprinting offers also a unique approach to studying the structure of proteins embedded within membranes or lipid bodies. All the biomolecular applications reported herein demonstrate that the Metrology beamline at SOLEIL can be successfully used for synchrotron X-ray footprinting of

  19. X-ray Studies of Regenerated Cellulose Fibers Wet Spun from Cotton Linter Pulp in NaOH/Thiourea Aqueous Solutions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen,X.; Burger, C.; Fang, D.

    Regenerated cellulose fibers were fabricated by dissolution of cotton linter pulp in NaOH (9.5 wt%) and thiourea (4.5 wt%) aqueous solution followed by wet-spinning and multi-roller drawing. The multi-roller drawing process involved three stages: coagulation (I), coagulation (II) and post-treatment (III). The crystalline structure and morphology of regenerated cellulose fiber was investigated by synchrotron wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) techniques. Results indicated that only the cellulose II crystal structure was found in regenerated cellulose fibers, proving that the cellulose crystals were completely transformed from cellulose I to II structure during spinning from NaOH/thiourea aqueous solution. Themore » crystallinity, orientation and crystal size at each stage were determined from the WAXD analysis. Drawing of cellulose fibers in the coagulation (II) bath (H{sub 2}SO{sub 4}/H{sub 2}O) was found to generate higher orientation and crystallinity than drawing in the post-treatment (III). Although the post-treatment process also increased crystal orientation, it led to a decrease in crystallinity with notable reduction in the anisotropic fraction. Compared with commercial rayon fibers fabricated by the viscose process, the regenerated cellulose fibers exhibited higher crystallinity but lower crystal orientation. SAXS results revealed a clear scattering maximum along the meridian direction in all regenerated cellulose fibers, indicating the formation of lamellar structure during spinning.« less

  20. Scattered radiation doses absorbed by technicians at different distances from X-ray exposure: Experiments on prosthesis.

    PubMed

    Chiang, Hsien-Wen; Liu, Ya-Ling; Chen, Tou-Rong; Chen, Chun-Lon; Chiang, Hsien-Jen; Chao, Shin-Yu

    2015-01-01

    This work aimed to investigate the spatial distribution of scattered radiation doses induced by exposure to the portable X-ray, the C-arm machine, and to simulate the radiologist without a shield of lead clothing, radiation doses absorbed by medical staff at 2 m from the central exposure point. With the adoption of the Rando Phantom, several frequently X-rayed body parts were exposed to X-ray radiation, and the scattered radiation doses were measured by ionization chamber dosimeters at various angles from the patient. Assuming that the central point of the X-ray was located at the belly button, five detection points were distributed in the operation room at 1 m above the ground and 1-2 m from the central point horizontally. The radiation dose measured at point B was the lowest, and the scattered radiation dose absorbed by the prosthesis from the X-ray's vertical projection was 0.07 ±0.03 μGy, which was less than the background radiation levels. The Fluke biomedical model 660-5DE (400 cc) and 660-3DE (4 cc) ion chambers were used to detect air dose at a distance of approximately two meters from the central point. The AP projection radiation doses at point B was the lowest (0.07±0.03 μGy) and the radiation doses at point D was the highest (0.26±0.08 μGy) .Only taking the vertical projection into account, the radiation doses at point B was the lowest (0.52 μGy), and the radiation doses at point E was the highest (4 μGy).The PA projection radiation at point B was the lowest (0.36 μGy) and the radiation doses at point E was the highest(2.77 μGy), occupying 10-32% of the maximum doses. The maximum dose in five directions was nine times to the minimum dose. When the PX and the C-arm machine were used, the radiation doses at a distance of 2 m were attenuated to the background radiation level. The radiologist without a lead shield should stand at point B of patient's feet. Accordingly, teaching materials on radiation safety for radiological interns and clinical

  1. Stellar X-Ray Polarimetry

    NASA Technical Reports Server (NTRS)

    Swank, J.

    2011-01-01

    Most of the stellar end-state black holes, pulsars, and white dwarfs that are X-ray sources should have polarized X-ray fluxes. The degree will depend on the relative contributions of the unresolved structures. Fluxes from accretion disks and accretion disk corona may be polarized by scattering. Beams and jets may have contributions of polarized emission in strong magnetic fields. The Gravity and Extreme Magnetism Small Explorer (GEMS) will study the effects on polarization of strong gravity of black holes and strong magnetism of neutron stars. Some part of the flux from compact stars accreting from companion stars has been reflected from the companion, its wind, or accretion streams. Polarization of this component is a potential tool for studying the structure of the gas in these binary systems. Polarization due to scattering can also be present in X-ray emission from white dwarf binaries and binary normal stars such as RS CVn stars and colliding wind sources like Eta Car. Normal late type stars may have polarized flux from coronal flares. But X-ray polarization sensitivity is not at the level needed for single early type stars.

  2. Microfluidic Chips for In Situ Crystal X-ray Diffraction and In Situ Dynamic Light Scattering for Serial Crystallography.

    PubMed

    Gicquel, Yannig; Schubert, Robin; Kapis, Svetlana; Bourenkov, Gleb; Schneider, Thomas; Perbandt, Markus; Betzel, Christian; Chapman, Henry N; Heymann, Michael

    2018-04-24

    This protocol describes fabricating microfluidic devices with low X-ray background optimized for goniometer based fixed target serial crystallography. The devices are patterned from epoxy glue using soft lithography and are suitable for in situ X-ray diffraction experiments at room temperature. The sample wells are lidded on both sides with polymeric polyimide foil windows that allow diffraction data collection with low X-ray background. This fabrication method is undemanding and inexpensive. After the sourcing of a SU-8 master wafer, all fabrication can be completed outside of a cleanroom in a typical research lab environment. The chip design and fabrication protocol utilize capillary valving to microfluidically split an aqueous reaction into defined nanoliter sized droplets. This loading mechanism avoids the sample loss from channel dead-volume and can easily be performed manually without using pumps or other equipment for fluid actuation. We describe how isolated nanoliter sized drops of protein solution can be monitored in situ by dynamic light scattering to control protein crystal nucleation and growth. After suitable crystals are grown, complete X-ray diffraction datasets can be collected using goniometer based in situ fixed target serial X-ray crystallography at room temperature. The protocol provides custom scripts to process diffraction datasets using a suite of software tools to solve and refine the protein crystal structure. This approach avoids the artefacts possibly induced during cryo-preservation or manual crystal handling in conventional crystallography experiments. We present and compare three protein structures that were solved using small crystals with dimensions of approximately 10-20 µm grown in chip. By crystallizing and diffracting in situ, handling and hence mechanical disturbances of fragile crystals is minimized. The protocol details how to fabricate a custom X-ray transparent microfluidic chip suitable for in situ serial crystallography

  3. Synchrotron x-ray thermal diffuse scattering probes for phonons in Si/SiGe/Si trilayer nanomembranes

    DOE PAGES

    McElhinny, Kyle M.; Gopalakrishnan, Gokul; Savage, Donald E.; ...

    2016-05-17

    Nanostructures offer the opportunity to control the vibrational properties of via the scattering of phonons due to boundaries and mass disorder as well as through changes in the phonon dispersion due to spatial confinement. Advances in understanding these effects have the potential to lead to thermoelectrics with an improved figure of merit by lowering the thermal conductivity and to provide insight into electron-phonon scattering rates in nanoelectronics. However, characterizing the phonon population in nanomaterials has been challenging because of their small volume and because optical techniques probe only a small fraction of reciprocal space. Recent developments in x-ray scattering nowmore » allow the phonon population to be evaluated across all of reciprocal space in samples with volumes as small as several cubic micrometers. We apply this approach, synchrotron x-ray thermal diffuse scattering (TDS), to probe the population of phonons within a Si/SiGe/Si trilayer nanomembrane. The distributions of scattered intensity from Si/SiGe/Si trilayer nanomembranes and Si nanomembranes with uniform composition are qualitatively similar, with features arising from the elastic anisotropy of the diamond structure. The TDS signal for the Si/SiGe/Si nanomembrane, however, has higher intensity than the Si membrane of the same total thickness by approximately 3.75%. Possible origins of the enhancement in scattering from SiGe in comparison with Si include the larger atomic scattering factor of Ge atoms within the SiGe layer or reduced phonon frequencies due to alloying.« less

  4. X-Ray Diffuse Scattering Study of the Kinetics of Stacking Fault Growth and Annihilation in Boron-Implanted Silicon.

    NASA Astrophysics Data System (ADS)

    Patel, J. R.

    2002-06-01

    Stacking faults in boron-implanted silicon give rise to streaks or rods of scattered x-ray intensity normal to the stacking fault plane. We have used the diffuse scattering rods to follow the growth of faults as a function of time when boron-implanted silicon is annealed in the range 925 - 1025 C.

  5. Spatial Quantum Beats in Vibrational Resonant Inelastic Soft X-Ray Scattering at Dissociating States in Oxygen

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pietzsch, A.; Kennedy, B.; Sun, Y.-P.

    2011-04-15

    Resonant inelastic soft x-ray scattering (RIXS) spectra excited at the 1{sigma}{sub g}{yields}3{sigma}{sub u} resonance in gas-phase O{sub 2} show excitations due to the nuclear degrees of freedom with up to 35 well-resolved discrete vibronic states and a continuum due to the kinetic energy distribution of the separated atoms. The RIXS profile demonstrates spatial quantum beats caused by two interfering wave packets with different momenta as the atoms separate. Thomson scattering strongly affects both the spectral profile and the scattering anisotropy.

  6. Neutron and x-ray scattering study of phonon dispersion and diffuse scattering in (Na ,Bi ) Ti O3-x BaTi O3 single crystals near the morphotropic phase boundary

    NASA Astrophysics Data System (ADS)

    Luo, Chengtao; Bansal, Dipanshu; Li, Jiefang; Viehland, Dwight; Winn, Barry; Ren, Yang; Li, Xiaobing; Luo, Haosu; Delaire, Olivier

    2017-11-01

    Neutron and x-ray scattering measurements were performed on (N a1 /2B i1 /2 ) Ti O3-x at %BaTi O3 (NBT-x BT ) single crystals (x =4 , 5, 6.5, and 7.5) across the morphotropic phase boundary (MPB), as a function of both composition and temperature, and probing both structural and dynamical aspects. In addition to the known diffuse scattering pattern near the Γ points, our measurements revealed new, faint superlattice peaks, as well as an extensive diffuse scattering network, revealing a short-range ordering of polar nanoregions (PNR) with a static stacking morphology. In samples with compositions closest to the MPB, our inelastic neutron scattering investigations of the phonon dynamics showed two unusual features in the acoustic phonon branches, between the superlattice points, and between the superlattice points and Γ points, respectively. These critical elements are not present in the other compositions away from the MPB, which suggests that these features may be related to the tilt modes coupling behavior near the MPB.

  7. X-ray magnetic circular dichroism measured at the Fe K-edge with a reduced intrinsic broadening: x-ray absorption spectroscopy versus resonant inelastic x-ray scattering measurements

    NASA Astrophysics Data System (ADS)

    Juhin, Amélie; Sainctavit, Philippe; Ollefs, Katharina; Sikora, Marcin; Filipponi, Adriano; Glatzel, Pieter; Wilhelm, Fabrice; Rogalev, Andrei

    2016-12-01

    X-ray magnetic circular dichroism is measured at the Fe K pre-edge in yttrium iron garnet using two different procedures that allow reducing the intrinsic broadening due to the 1s corehole lifetime. First, deconvolution of XMCD data measured in total fluorescence yield (TFY) with an extremely high signal-to-noise ratio enables a factor of 2.4 to be gained in the XMCD intensity. Ligand field multiplet calculations performed with different values of intrinsic broadening show that deconvolving such high quality XMCD data is similar to reducing the lifetime broadening from a 1s corehole to a 2p corehole. Second, MCD is measured by resonant inelastic x-ray scattering spectroscopy as a function of incident energy and emission energy. Selection of a fixed emission energy, instead of using the TFY, allows enhancing the MCD intensity up to a factor of  ˜4.7. However, this significantly changes the spectral shape of the XMCD signal, which cannot be interpreted any more as an absorption spectrum.

  8. Soft x-ray scattering facility at the Advanced Light Source with real-time data processing and analysis.

    PubMed

    Gann, E; Young, A T; Collins, B A; Yan, H; Nasiatka, J; Padmore, H A; Ade, H; Hexemer, A; Wang, C

    2012-04-01

    We present the development and characterization of a dedicated resonant soft x-ray scattering facility. Capable of operation over a wide energy range, the beamline and endstation are primarily used for scattering from soft matter systems around the carbon K-edge (∼285 eV). We describe the specialized design of the instrument and characteristics of the beamline. Operational characteristics of immediate interest to users such as polarization control, degree of higher harmonic spectral contamination, and detector noise are delineated. Of special interest is the development of a higher harmonic rejection system that improves the spectral purity of the x-ray beam. Special software and a user-friendly interface have been implemented to allow real-time data processing and preliminary data analysis simultaneous with data acquisition. © 2012 American Institute of Physics

  9. High-temperature cuprate superconductors studied by x-ray Compton scattering and positron annihilation spectroscopies

    NASA Astrophysics Data System (ADS)

    Barbiellini, Bernardo

    2013-06-01

    The bulk Fermi surface in an overdoped (x = 0.3) single crystal of La2-xSrxCuO4 has been observed by using x-ray Compton scattering. This momentum density technique also provides a powerful tool for directly seeing what the dopant Sr atoms are doing to the electronic structure of La2CuO4. Because of wave function effects, positron annihilation spectroscopy does not yield a strong signature of the Fermi surface in extended momentum space, but it can be used to explore the role of oxygen defects in the reservoir layers for promoting high temperature superconductivity.

  10. PAL-XFEL soft X-ray scientific instruments and X-ray optics: First commissioning results

    NASA Astrophysics Data System (ADS)

    Park, Sang Han; Kim, Minseok; Min, Changi-Ki; Eom, Intae; Nam, Inhyuk; Lee, Heung-Soo; Kang, Heung-Sik; Kim, Hyeong-Do; Jang, Ho Young; Kim, Seonghan; Hwang, Sun-min; Park, Gi-Soo; Park, Jaehun; Koo, Tae-Yeong; Kwon, Soonnam

    2018-05-01

    We report an overview of soft X-ray scientific instruments and X-ray optics at the free electron laser (FEL) of the Pohang Accelerator Laboratory, with selected first-commissioning results. The FEL exhibited a pulse energy of 200 μJ/pulse, a pulse width of <50 fs full width at half maximum, and an energy bandwidth of 0.44% at a photon energy of 850 eV. Monochromator resolving power of 10 500 was achieved. The estimated total time resolution between optical laser and X-ray pulses was <270 fs. A resonant inelastic X-ray scattering spectrometer was set up; its commissioning results are also reported.

  11. X-ray diffraction-based electronic structure calculations and experimental x-ray analysis for medical and materials applications

    NASA Astrophysics Data System (ADS)

    Mahato, Dip Narayan

    This thesis includes x-ray experiments for medical and materials applications and the use of x-ray diffraction data in a first-principles study of electronic structures and hyperfine properties of chemical and biological systems. Polycapillary focusing lenses were used to collect divergent x rays emitted from conventional x-ray tubes and redirect them to form an intense focused beam. These lenses are routinely used in microbeam x-ray fluorescence analysis. In this thesis, their potential application to powder diffraction and focused beam orthovoltage cancer therapy has been investigated. In conventional x-ray therapy, very high energy (˜ MeV) beams are used, partly to reduce the skin dose. For any divergent beam, the dose is necessarily highest at the entry point, and decays exponentially into the tissue. To reduce the skin dose, high energy beams, which have long absorption lengths, are employed, and rotated about the patient to enter from different angles. This necessitates large expensive specialized equipment. A focused beam could concentrate the dose within the patient. Since this is inherently skin dose sparing, lower energy photons could be employed. A primary concern in applying focused beams to therapy is whether the focus would be maintained despite Compton scattering within the tissue. To investigate this, transmission and focal spot sizes as a function of photon energy of two polycapillary focusing lenses were measured. The effects of tissue-equivalent phantoms of different thicknesses on the focal spot size were studied. Scatter fraction and depth dose were calculated. For powder diffraction, the polycapillary optics provide clean Gaussian peaks, which result in angular resolution that is much smaller than the peak width due to the beam convergence. Powder diffraction (also called coherent scatter) without optics can also be used to distinguish between tissue types that, because they have different nanoscale structures, scatter at different angles

  12. X-ray and Raman scattering study of orientational order in nematic and heliconical nematic liquid crystals.

    PubMed

    Singh, Gautam; Fu, Jinxin; Agra-Kooijman, Dena M; Song, Jang-Kun; Vengatesan, M R; Srinivasarao, Mohan; Fisch, Michael R; Kumar, Satyendra

    2016-12-01

    The temperature dependence of the orientational order parameters 〈P_{2}(cosβ)〉 and 〈P_{4}(cosβ)〉 in the nematic (N) and twist-bend nematic (N_{tb}) phases of the liquid crystal dimer CB7CB have been measured using x-ray and polarized Raman scattering. The 〈P_{2}(cosβ)〉 obtained from both techniques are the same, while 〈P_{4}(cosβ)〉, determined by Raman scattering is, as expected, systematically larger than its x-ray value. Both order parameters increase in the N phase with decreasing temperature, drop across the N-N_{tb} transition, and continue to decrease. In the N_{tb} phase, the x-ray value of 〈P_{4}(cosβ)〉 eventually becomes negative, providing a direct and independent confirmation of a conical molecular orientational distribution. The heliconical tilt angle α, determined from orientational distribution functions in the N_{tb} phase, increases to ∼24^{∘} at ∼15 K below the transition. In the N_{tb} phase, α(T)∝(T^{*}-T)^{λ}, with λ=0.19±0.03. The transition supercools by 1.7 K, consistent with its weakly first-order nature. The value of λ is close to 0.25 indicating close proximity to a tricritical point.

  13. Kinetics of Polymer-Fullerene Phase Separation during Solvent Annealing Studied by Table-Top X-ray Scattering.

    PubMed

    Vegso, Karol; Siffalovic, Peter; Jergel, Matej; Nadazdy, Peter; Nadazdy, Vojtech; Majkova, Eva

    2017-03-08

    Solvent annealing is an efficient way of phase separation in polymer-fullerene blends to optimize bulk heterojunction morphology of active layer in polymer solar cells. To track the process in real time across all relevant stages of solvent evaporation, laboratory-based in situ small- and wide-angle X-ray scattering measurements were applied simultaneously to a model P3HT:PCBM blend dissolved in dichlorobenzene. The PCBM molecule agglomeration starts at ∼7 wt % concentration of solid content of the blend in solvent. Although PCBM agglomeration is slowed-down at ∼10 wt % of solid content, the rate constant of phase separation is not changed, suggesting agglomeration and reordering of P3HT molecular chains. Having the longest duration, this stage most affects BHJ morphology. Phase separation is accelerated rapidly at concentration of ∼25 wt %, having the same rate constant as the growth of P3HT crystals. P3HT crystallization is driving force for phase separation at final stages before a complete solvent evaporation, having no visible temporal overlap with PCBM agglomeration. For the first time, such a study was done in laboratory demonstrating potential of the latest generation table-top high-brilliance X-ray source as a viable alternative before more sophisticated X-ray scattering experiments at synchrotron facilities are performed.

  14. Effect of surface roughness and subsurface damage on grazing-incidence x-ray scattering and specular reflectance.

    PubMed

    Lodha, G S; Yamashita, K; Kunieda, H; Tawara, Y; Yu, J; Namba, Y; Bennett, J M

    1998-08-01

    Grazing-incidence specular reflectance and near-specular scattering were measured at Al-K(alpha) (1.486-keV, 8.34-?) radiation on uncoated dielectric substrates whose surface topography had been measured with a scanning probe microscope and a mechanical profiler. Grazing-incidence specular reflectance was also measured on selected substrates at the Cu-K(alpha) (8.047-keV, 1.54-?) wavelength. Substrates included superpolished and conventionally polished fused silica; SiO(2) wafers; superpolished and precision-ground Zerodur; conventionally polished, float-polished, and precision-ground BK-7 glass; and superpolished and precision-ground silicon carbide. Roughnesses derived from x-ray specular reflectance and scattering measurements were in good agreement with topographic roughness values measured with a scanning probe microscope (atomic force microscope) and a mechanical profiler that included similar ranges of surface spatial wavelengths. The specular reflectance was also found to be sensitive to the density of polished surface layers and subsurface damage down to the penetration depth of the x rays. Density gradients and subsurface damage were found in the superpolished fused-silica and precision-ground Zerodur samples. These results suggest that one can nondestructively evaluate subsurface damage in transparent materials using grazing-incidence x-ray specular reflectance in the 1.5-8-keV range.

  15. How to improve x-ray scattering techniques to quantify bone mineral density using spectroscopy

    PubMed Central

    Krmar, M.; Ganezer, K.

    2012-01-01

    Purpose: The purpose of this study was to develop a new diagnostic technique for measuring bone mineral density (BMD) for the assessment of osteoporosis, which improves upon the coherent to Compton scattering ratio (CCSR) method, which was first developed in the 1980s. To help the authors achieve these goals, they have identified and studied two new indices for CCSR, the forward scattered to backward scattered (FS-BS) and the forward scattered to transmitted (FS-T) ratios. They believe that, at small angles, these two parameters can offer a practical in vivo determination of BMD that can be used to overcome the limitations of past CCSR systems, including high radiation dosages, costs, and examination durations. Methods: In previous CCSR studies, a high-activity radioactive source with a long half-live (usually 241Am) and an expensive and bulky cryogenic HPGe detector were applied to both in vivo and in vitro measurements. To make this technique more suitable for clinical applications, the possibility of using a standard diagnostic x-ray tube generating a continuous spectrum was investigated in this paper. Scattered radiation from trabecular bone-simulating phantoms containing various mineral densities that span the normal range of in vivo BMD was collected in this study using relatively inexpensive noncryogenic CdTe or NaI detectors. Results: The initial results demonstrate that a modified version of CCSR can be successfully applied to trabecular bone assessment using a diagnostic x-ray tube with a continuous spectrum in two variations, the FS-BS and the FS-T ratio. When FS-BS is measured, intensity spectra in the forward and backward directions must be collected while FS-T requires only the integral intensity of the scattered and transmitted (T) spectra in the energy region above 40 keV. For both of these methods, forward scattering angles less than or equal to 15° and backward scattering angles greater than or equal to (165°= 180° − 15°) are needed

  16. Grazing-incidence small-angle X-ray scattering (GISAXS) on small periodic targets using large beams

    PubMed Central

    Soltwisch, Victor; Probst, Jürgen; Scholze, Frank; Krumrey, Michael

    2017-01-01

    Grazing-incidence small-angle X-ray scattering (GISAXS) is often used as a versatile tool for the contactless and destruction-free investigation of nano­structured surfaces. However, due to the shallow incidence angles, the footprint of the X-ray beam is significantly elongated, limiting GISAXS to samples with typical target lengths of several millimetres. For many potential applications, the production of large target areas is impractical, and the targets are surrounded by structured areas. Because the beam footprint is larger than the targets, the surrounding structures contribute parasitic scattering, burying the target signal. In this paper, GISAXS measurements of isolated as well as surrounded grating targets in Si substrates with line lengths from 50 µm down to 4 µm are presented. For the isolated grating targets, the changes in the scattering patterns due to the reduced target length are explained. For the surrounded grating targets, the scattering signal of a 15 µm × 15 µm target grating structure is separated from the scattering signal of 100 µm × 100 µm nanostructured surroundings by producing the target with a different orientation with respect to the predominant direction of the surrounding structures. As virtually all litho­graphically produced nanostructures have a predominant direction, the described technique allows GISAXS to be applied in a range of applications, e.g. for characterization of metrology fields in the semiconductor industry, where up to now it has been considered impossible to use this method due to the large beam footprint. PMID:28875030

  17. Grazing-incidence small-angle X-ray scattering (GISAXS) on small periodic targets using large beams.

    PubMed

    Pflüger, Mika; Soltwisch, Victor; Probst, Jürgen; Scholze, Frank; Krumrey, Michael

    2017-07-01

    Grazing-incidence small-angle X-ray scattering (GISAXS) is often used as a versatile tool for the contactless and destruction-free investigation of nano-structured surfaces. However, due to the shallow incidence angles, the footprint of the X-ray beam is significantly elongated, limiting GISAXS to samples with typical target lengths of several millimetres. For many potential applications, the production of large target areas is impractical, and the targets are surrounded by structured areas. Because the beam footprint is larger than the targets, the surrounding structures contribute parasitic scattering, burying the target signal. In this paper, GISAXS measurements of isolated as well as surrounded grating targets in Si substrates with line lengths from 50 µm down to 4 µm are presented. For the isolated grating targets, the changes in the scattering patterns due to the reduced target length are explained. For the surrounded grating targets, the scattering signal of a 15 µm × 15 µm target grating structure is separated from the scattering signal of 100 µm × 100 µm nanostructured surroundings by producing the target with a different orientation with respect to the predominant direction of the surrounding structures. As virtually all litho-graphically produced nanostructures have a predominant direction, the described technique allows GISAXS to be applied in a range of applications, e.g.  for characterization of metrology fields in the semiconductor industry, where up to now it has been considered impossible to use this method due to the large beam footprint.

  18. Femtosecond x-ray scattering study of ultrafast photoinduced structural dynamics in solvated [ Co ( terpy ) 2 ] 2 +

    DOE PAGES

    Biasin, Elisa; van Driel, Tim Brandt; Kjær, Kasper S.; ...

    2016-06-30

    Here, we study the structural dynamics of photoexcited [Co(terpy) 2] 2+ in an aqueous solution with ultrafast x-ray diffuse scattering experiments conducted at the Linac Coherent Light Source. Through direct comparisons with density functional theory calculations, our analysis shows that the photoexcitation event leads to elongation of the Co-N bonds, followed by coherent Co-N bond length oscillations arising from the impulsive excitation of a vibrational mode dominated by the symmetrical stretch of all six Co-N bonds. This mode has a period of 0.33 ps and decays on a subpicosecond time scale. We find that the equilibrium bond-elongated structure of themore » high spin state is established on a single-picosecond time scale and that this state has a lifetime of ~7 ps.« less

  19. Investigating the origins of nanostructural variations in differential ethnic hair types using X-ray scattering techniques.

    PubMed

    Wade, M; Tucker, I; Cunningham, P; Skinner, R; Bell, F; Lyons, T; Patten, K; Gonzalez, L; Wess, T

    2013-10-01

    Human hair is a major determinant of visual ethnic differentiation. Although hair types are celebrated as part of our ethnic diversity, the approach to hair care has made the assumption that hair types are structurally and chemically similar. Although this is clearly not the case at the macroscopic level, the intervention of many hair treatments is at the nanoscopic and molecular levels. The purpose of the work presented here is to identify the main nanoscopic and molecular hierarchical differences across five different ethnic hair types from hair fibres taken exclusively from the scalp. These are Afro (subdivided into elastic 'rubber' and softer non-elastic 'soft'), Chinese, European and Mullato (mixed race). Small angle X-Ray scattering (SAXS) is a technique capable of resolving nanostructural variations in complex materials. Individual hair fibres from different ethnic hair types were used to investigate structural features found in common and also specific to each type. Simultaneous wide angle X-Ray scattering (WAXS) was used to analyse the submolecular level structure of the fibrous keratin present. The data sets from both techniques were analysed with principal component analysis (PCA) to identify underlying variables. Principal component analysis of both SAXS and WAXS data was shown to discriminate the scattering signal between different hair types. The X-ray scattering results show a common underlying keratin intermediate filament (KIF) structure. However, distinct differences were observed in the preferential orientation and intensity signal from the lipid component of the hair. In addition, differences were observed in the intensity distribution of the very low-angle sample-dependent diffuse scatter surrounding the 'beamstop.' The results indicate that the fibrous keratin scaffold remains consistent between ethnic hair types. The hierarchies made by these may be modulated by variation in the content of keratin-associated proteins (KAPs) and lipids that

  20. Coherent x-ray diffraction

    NASA Astrophysics Data System (ADS)

    Pitney, John Allen

    Conventional x-ray diffraction has historically been done under conditions such that the measured signal consists of an incoherent addition of scattering which is coherent only on a length scale determined by the properties of the beam. The result of the incoherent summation is a statistical averaging over the whole illuminated volume of the sample, which yields certain kinds of information with a high degree of precision and has been key to the success of x-ray diffraction in a variety of applications. Coherent x-ray scattering techniques, such as coherent x-ray diffraction (CXD) and x-ray intensity fluctuation spectroscopy (XIFS), attempt to reduce or eliminate any incoherent averaging so that specific, local structures couple to the measurement without being averaged out. In the case of XIFS, the result is analogous to dynamical light scattering, but with sensitivity to length scales less than 200 nm and time scales from 10-3 s to 103 s. When combined with phase retrieval, CXD represents an imaging technique with the penetration, in situ capabilities, and contrast mechanisms associated with x-rays and with a spatial resolution ultimately limited by the x-ray wavelength. In practice, however, the spatial resolution of CXD imaging is limited by exposure to about 100 A. This thesis describes CXD measurements of the binary alloy Cu3Au and the adaptation of phase retrieval methods for the reconstruction of real-space images of Cu3Au antiphase domains. The theoretical foundations of CXD are described in Chapter 1 as derived from the kinematical formulation for x-ray diffraction and from the temporal and spatial coherence of radiation. The antiphase domain structure of Cu 3Au is described, along with the associated reciprocal-space structure which is measured by CXD. CXD measurements place relatively stringent requirements on the coherence properties of the beam and on the detection mechanism of the experiment; these requirements and the means by which they have been

  1. Small-angle X-Ray analysis of macromolecular structure: the structure of protein NS2 (NEP) in solution

    NASA Astrophysics Data System (ADS)

    Shtykova, E. V.; Bogacheva, E. N.; Dadinova, L. A.; Jeffries, C. M.; Fedorova, N. V.; Golovko, A. O.; Baratova, L. A.; Batishchev, O. V.

    2017-11-01

    A complex structural analysis of nuclear export protein NS2 (NEP) of influenza virus A has been performed using bioinformatics predictive methods and small-angle X-ray scattering data. The behavior of NEP molecules in a solution (their aggregation, oligomerization, and dissociation, depending on the buffer composition) has been investigated. It was shown that stable associates are formed even in a conventional aqueous salt solution at physiological pH value. For the first time we have managed to get NEP dimers in solution, to analyze their structure, and to compare the models obtained using the method of the molecular tectonics with the spatial protein structure predicted by us using the bioinformatics methods. The results of the study provide a new insight into the structural features of nuclear export protein NS2 (NEP) of the influenza virus A, which is very important for viral infection development.

  2. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

    NASA Astrophysics Data System (ADS)

    Swadling, G. F.; Ross, J. S.; Datte, P.; Moody, J.; Divol, L.; Jones, O.; Landen, O.

    2016-11-01

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause "blanking" (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ˜8 J cm-2. This is significantly above the expected threshold for the onset of "blanking" effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate "blanking." Estimates suggest that an areal density of 1019 cm-2 Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

  3. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic.

    PubMed

    Swadling, G F; Ross, J S; Datte, P; Moody, J; Divol, L; Jones, O; Landen, O

    2016-11-01

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause "blanking" (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated to be ∼8 J cm -2 . This is significantly above the expected threshold for the onset of "blanking" effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate "blanking." Estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.

  4. On scattered waves and lipid domains: detecting membrane rafts with X-rays and neutrons

    DOE PAGES

    Marquardt, Drew; Heberle, Frederick A.; Nickels, Jonathan D.; ...

    2015-09-21

    In order to understand the biological role of lipids in cell membranes, it is necessary to determine the mesoscopic structure of well-defined model membrane systems. Neutron and X-ray scattering are non-invasive, probe-free techniques that have been used extensively in such systems to probe length scales ranging from angstroms to microns, and dynamics occurring over picosecond to millisecond time scales. Finally, recent developments in the area of phase separated lipid systems mimicking membrane rafts will be presented, and the underlying concepts of the different scattering techniques used to study them will be discussed in detail.

  5. Noninvasive Synchrotron-Based X-ray Raman Scattering Discriminates Carbonaceous Compounds in Ancient and Historical Materials [ In situ synchrotron-based X-Ray Raman scattering discriminates carbonaceous compounds in ancient and historical materials

    DOE PAGES

    Gueriau, Pierre; Rueff, Jean -Pascal; Bernard, Sylvain; ...

    2017-09-13

    Carbon compounds are ubiquitous and occur in a diversity of chemical forms in many systems including ancient and historic materials ranging from cultural heritage to paleontology. Determining their speciation cannot only provide unique information on their origin but may also elucidate degradation processes. Synchrotron-based X-ray absorption near-edge structure (XANES) spectroscopy at the carbon K-edge (280–350 eV) is a very powerful method to probe carbon speciation. However, the short penetration depth of soft X-rays imposes stringent constraints on sample type, preparation, and analytical environment. A hard X-ray probe such as X-ray Raman scattering (XRS) can overcome many of these difficulties. Heremore » we report the use of XRS at ~6 keV incident energy to collect carbon K-edge XANES data and probe the speciation of organic carbon in several specimens relevant to cultural heritage and natural history. This methodology enables the measurement to be done in a nondestructive way, in air, and provides information that is not compromised by surface contamination by ensuring that the dominant signal contribution is from the bulk of the probed material. Using the backscattering geometry at large photon momentum transfer maximizes the XRS signal at the given X-ray energy and enhances nondipole contributions compared to conventional XANES, thereby augmenting the speciation sensitivity. The capabilities and limitations of the technique are discussed. As a result, we show that despite its small cross section, for a range of systems the XRS method can provide satisfactory signals at realistic experimental conditions. XRS constitutes a powerful complement to FT-IR, Raman, and conventional XANES spectroscopy, overcoming some of the limitations of these techniques.« less

  6. Analysis of small-angle X-ray scattering data in the presence of significant instrumental smearing

    PubMed Central

    Bergenholtz, Johan; Ulama, Jeanette; Zackrisson Oskolkova, Malin

    2016-01-01

    A laboratory-scale small-angle X-ray scattering instrument with pinhole collimation has been used to assess smearing effects due to instrumental resolution. A new, numerically efficient method to smear ideal model intensities is developed and presented. It allows for directly using measured profiles of isotropic but otherwise arbitrary beams in smearing calculations. Samples of low-polydispersity polymer spheres have been used to show that scattering data can in this way be quantitatively modeled even when there is substantial distortion due to instrumental resolution. PMID:26937235

  7. Quasi-particle Interference of Heavy Fermions in Resonant X-ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gyenis, Andras; da Silva Neto, Eduardo H.; Sutarto, Ronny

    Resonant x-ray scattering (RXS) has recently become an increasingly important tool for the study of ordering phenomena in correlated electron systems. Yet, the interpretation of RXS experiments remains theoretically challenging because of the complexity of the RXS cross section. Central to this debate is the recent proposal that impurity-induced Friedel oscillations, akin to quasi-particle interference signals observed with a scanning tunneling microscope (STM), can lead to scattering peaks in RXS experiments. The possibility that quasi-particle properties can be probed in RXS measurements opens up a new avenue to study the bulk band structure of materials with the orbital and elementmore » selectivity provided by RXS. We test these ideas by combining RXS and STM measurements of the heavy fermion compound CeMIn5 (M = Co, Rh). Temperature- and doping-dependent RXS measurements at the Ce-M4 edge show a broad scattering enhancement that correlates with the appearance of heavy f-electron bands in these compounds. The scattering enhancement is consistent with the measured quasi-particle interference signal in the STM measurements, indicating that the quasi-particle interference can be probed through the momentum distribution of RXS signals. Overall, our experiments demonstrate new opportunities for studies of correlated electronic systems using the RXS technique.« less

  8. Quasi-particle interference of heavy fermions in resonant x-ray scattering

    PubMed Central

    Gyenis, András; da Silva Neto, Eduardo H.; Sutarto, Ronny; Schierle, Enrico; He, Feizhou; Weschke, Eugen; Kavai, Mariam; Baumbach, Ryan E.; Thompson, Joe D.; Bauer, Eric D.; Fisk, Zachary; Damascelli, Andrea; Yazdani, Ali; Aynajian, Pegor

    2016-01-01

    Resonant x-ray scattering (RXS) has recently become an increasingly important tool for the study of ordering phenomena in correlated electron systems. Yet, the interpretation of RXS experiments remains theoretically challenging because of the complexity of the RXS cross section. Central to this debate is the recent proposal that impurity-induced Friedel oscillations, akin to quasi-particle interference signals observed with a scanning tunneling microscope (STM), can lead to scattering peaks in RXS experiments. The possibility that quasi-particle properties can be probed in RXS measurements opens up a new avenue to study the bulk band structure of materials with the orbital and element selectivity provided by RXS. We test these ideas by combining RXS and STM measurements of the heavy fermion compound CeMIn5 (M = Co, Rh). Temperature- and doping-dependent RXS measurements at the Ce-M4 edge show a broad scattering enhancement that correlates with the appearance of heavy f-electron bands in these compounds. The scattering enhancement is consistent with the measured quasi-particle interference signal in the STM measurements, indicating that the quasi-particle interference can be probed through the momentum distribution of RXS signals. Overall, our experiments demonstrate new opportunities for studies of correlated electronic systems using the RXS technique. PMID:27757422

  9. Quasi-particle Interference of Heavy Fermions in Resonant X-ray Scattering

    DOE PAGES

    Gyenis, Andras; da Silva Neto, Eduardo H.; Sutarto, Ronny; ...

    2016-10-14

    Resonant x-ray scattering (RXS) has recently become an increasingly important tool for the study of ordering phenomena in correlated electron systems. Yet, the interpretation of RXS experiments remains theoretically challenging because of the complexity of the RXS cross section. Central to this debate is the recent proposal that impurity-induced Friedel oscillations, akin to quasi-particle interference signals observed with a scanning tunneling microscope (STM), can lead to scattering peaks in RXS experiments. The possibility that quasi-particle properties can be probed in RXS measurements opens up a new avenue to study the bulk band structure of materials with the orbital and elementmore » selectivity provided by RXS. We test these ideas by combining RXS and STM measurements of the heavy fermion compound CeMIn5 (M = Co, Rh). Temperature- and doping-dependent RXS measurements at the Ce-M4 edge show a broad scattering enhancement that correlates with the appearance of heavy f-electron bands in these compounds. The scattering enhancement is consistent with the measured quasi-particle interference signal in the STM measurements, indicating that the quasi-particle interference can be probed through the momentum distribution of RXS signals. Overall, our experiments demonstrate new opportunities for studies of correlated electronic systems using the RXS technique.« less

  10. Quasi-particle interference of heavy fermions in resonant x-ray scattering.

    PubMed

    Gyenis, András; da Silva Neto, Eduardo H; Sutarto, Ronny; Schierle, Enrico; He, Feizhou; Weschke, Eugen; Kavai, Mariam; Baumbach, Ryan E; Thompson, Joe D; Bauer, Eric D; Fisk, Zachary; Damascelli, Andrea; Yazdani, Ali; Aynajian, Pegor

    2016-10-01

    Resonant x-ray scattering (RXS) has recently become an increasingly important tool for the study of ordering phenomena in correlated electron systems. Yet, the interpretation of RXS experiments remains theoretically challenging because of the complexity of the RXS cross section. Central to this debate is the recent proposal that impurity-induced Friedel oscillations, akin to quasi-particle interference signals observed with a scanning tunneling microscope (STM), can lead to scattering peaks in RXS experiments. The possibility that quasi-particle properties can be probed in RXS measurements opens up a new avenue to study the bulk band structure of materials with the orbital and element selectivity provided by RXS. We test these ideas by combining RXS and STM measurements of the heavy fermion compound Ce M In 5 ( M = Co, Rh). Temperature- and doping-dependent RXS measurements at the Ce- M 4 edge show a broad scattering enhancement that correlates with the appearance of heavy f -electron bands in these compounds. The scattering enhancement is consistent with the measured quasi-particle interference signal in the STM measurements, indicating that the quasi-particle interference can be probed through the momentum distribution of RXS signals. Overall, our experiments demonstrate new opportunities for studies of correlated electronic systems using the RXS technique.

  11. Inelastic X-ray Scattering Studies of Plasmons in Carbon Nanotubes

    NASA Astrophysics Data System (ADS)

    Upton, M. H.; Klie, R. F.; Hill, J. P.; Gog, T.; Casa, D.; Ku, W.; Zhu, Y.; Sfeir, M. Y.; Misewich, J.; Eres, G.; Lowndes, D.

    2007-03-01

    We investigate the physical parameters controlling the low energy screening in carbon nanotubes via electron energy loss spectroscopy and inelastic x-ray scattering. Two plasmon-like features are observed, one near 9 eV (the so- called π plasmon) and one near 20 eV (the so-called π+σ plasmon). At large nanotube diameters, the π+σ plasmon energies depend exclusively on the number of walls and not on the radius or chiral vector. This shift indicates a change of strength of screening and the effective interaction at inter-atomic distance, and thus suggests an alternative mechanism of tuning the properties of the nanotube in addition to the well-known control provided by chirality and tube diameter.

  12. Diffuse scattering measurements of static atomic displacements in crystalline binary solid solutions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ice, G.E.; Sparks, C.J.; Jiang, X.

    1997-09-01

    Diffuse x-ray scattering from crystalline solid solutions is sensitive to both local chemical order and local bond distances. In short-range ordered alloys, fluctuations of chemistry and bond distances break the long-range symmetry of the crystal within a local region and contribute to the total energy of the alloy. Recent use of tunable synchrotron radiation to change the x-ray scattering contrast between elements has greatly advanced the measurement of bond distances between the three kinds of atom pairs found in crystalline binary alloys. The estimated standard deviation on these recovered static displacements approaches {+-}0.001 {angstrom} (0.0001 nm) which is an ordermore » of magnitude more precise than obtained with EXAFS. In addition, both the radial and tangential displacements can be recovered to five near neighbors and beyond. These static displacement measurements provide new information which challenges the most advanced theoretical models of binary crystalline alloys. 29 refs., 8 figs., 2 tabs.« less

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

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xiang, Dao; Ding, Yuantao; Raubenheimer, Tor

    2012-05-10

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

  14. X-ray scattering measurements on imploding CH spheres at the National Ignition Facility

    DOE PAGES

    Kraus, D.; Chapman, D. A.; Kritcher, A. L.; ...

    2016-07-21

    In this study, we have performed spectrally resolved x-ray scattering measurements on highly compressed polystyrene at pressures of several tens of TPa (100 Mbar) created by spherically convergent shocks at the National Ignition Facility. Scattering data of line radiation at 9.0 keV were recorded from the dense plasma shortly after shock coalescence. Accounting for spatial gradients, opacity effects, and source broadening, we demonstrate the sensitivity of the elastic scattering component to carbon K -shell ionization while at the same time constraining the temperature of the dense plasma. Finally, for six times compressed polystyrene, we find an average temperature of 86more » eV and carbon ionization state of 4.9, indicating that widely used ionization models need revision in order to be suitable for the extreme states of matter tested in our experiment.« less

  15. ON THE LATE-TIME SPECTRAL SOFTENING FOUND IN X-RAY AFTERGLOWS OF GAMMA-RAY BURSTS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Yuan-Zhu; Liang, En-Wei; Lu, Zu-Jia

    2016-02-20

    Strong spectral softening has been revealed in the late X-ray afterglows of some gamma-ray bursts (GRBs). The scenario of X-ray scattering around the circumburst dusty medium has been supported by previous works due to its overall successful prediction of both the temporal and spectral evolution of some X-ray afterglows. To further investigate the observed feature of spectral softening we now systematically search the X-ray afterglows detected by the X-ray telescope aboard Swift and collect 12 GRBs with significant late-time spectral softening. We find that dust scattering could be the dominant radiative mechanism for these X-ray afterglows regarding their temporal andmore » spectral features. For some well-observed bursts with high-quality data, the time-resolved spectra could be well-produced within the scattering scenario by taking into account the X-ray absorption from the circumburst medium. We also find that during spectral softening the power-law index in the high-energy end of the spectra does not vary much. The spectral softening is mainly manifested by the spectral peak energy continually moving to the soft end.« less

  16. Phonon Lifetime Observation in Epitaxial ScN Film with Inelastic X-Ray Scattering Spectroscopy.

    PubMed

    Uchiyama, H; Oshima, Y; Patterson, R; Iwamoto, S; Shiomi, J; Shimamura, K

    2018-06-08

    Phonon-phonon scattering dominates the thermal properties in nonmetallic materials, and it directly influences device performance in applications. The understanding of the scattering has been progressing using computational approaches, and the direct and systematic observation of phonon modes that include momentum dependences is desirable. We report experimental data on the phonon dispersion curves and lifetimes in an epitaxially grown ScN film using inelastic x-ray scattering measurements. The momentum dependence of the optical phonon lifetimes is estimated from the spectral width, and the highest-energy phonon mode around the zone center is found to possess a short lifetime of 0.21 ps. A comparison with first-principles calculations shows that our observed phonon lifetimes are quantitatively explained by three-body phonon-phonon interactions.

  17. Phonon Lifetime Observation in Epitaxial ScN Film with Inelastic X-Ray Scattering Spectroscopy

    NASA Astrophysics Data System (ADS)

    Uchiyama, H.; Oshima, Y.; Patterson, R.; Iwamoto, S.; Shiomi, J.; Shimamura, K.

    2018-06-01

    Phonon-phonon scattering dominates the thermal properties in nonmetallic materials, and it directly influences device performance in applications. The understanding of the scattering has been progressing using computational approaches, and the direct and systematic observation of phonon modes that include momentum dependences is desirable. We report experimental data on the phonon dispersion curves and lifetimes in an epitaxially grown ScN film using inelastic x-ray scattering measurements. The momentum dependence of the optical phonon lifetimes is estimated from the spectral width, and the highest-energy phonon mode around the zone center is found to possess a short lifetime of 0.21 ps. A comparison with first-principles calculations shows that our observed phonon lifetimes are quantitatively explained by three-body phonon-phonon interactions.

  18. SU-E-I-09: The Impact of X-Ray Scattering On Image Noise for Dedicated Breast CT

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, K; Gazi, P; Boone, J

    2015-06-15

    Purpose: To quantify the impact of detected x-ray scatter on image noise in flat panel based dedicated breast CT systems and to determine the optimal scanning geometry given practical trade-offs between radiation dose and scatter reduction. Methods: Four different uniform polyethylene cylinders (104, 131, 156, and 184 mm in diameter) were scanned as the phantoms on a dedicated breast CT scanner developed in our laboratory. Both stationary projection imaging and rotational cone-beam CT imaging was performed. For each acquisition type, three different x-ray beam collimations were used (12, 24, and 109 mm measured at isocenter). The aim was to quantifymore » image noise properties (pixel variance, SNR, and image NPS) under different levels of x-ray scatter, in order to optimize the scanning geometry. For both projection images and reconstructed CT images, individual pixel variance and NPS were determined and compared. Noise measurement from the CT images were also performed with different detector binning modes and reconstruction matrix sizes. Noise propagation was also tracked throughout the intermediate steps of cone-beam CT reconstruction, including the inverse-logarithmic process, Fourier-filtering before backprojection. Results: Image noise was lower in the presence of higher scatter levels. For the 184 mm polyethylene phantom, the image noise (measured in pixel variance) was ∼30% lower with full cone-beam acquisition compared to a narrow (12 mm) fan-beam acquisition. This trend is consistent across all phantom sizes and throughout all steps of CT image reconstruction. Conclusion: From purely a noise perspective, the cone-beam geometry (i.e. the full cone-angle acquisition) produces lower image noise compared to the lower-scatter fan-beam acquisition for breast CT. While these results are relevant in homogeneous phantoms, the full impact of scatter on noise in bCT should involve contrast-to-noise-ratio measurements in heterogeneous phantoms if the goal is to

  19. High-energy-resolution diced spherical quartz analyzers for resonant inelastic X-ray scattering

    DOE PAGES

    Said, Ayman H.; Gog, Thomas; Wieczorek, Michael; ...

    2018-02-15

    A novel diced spherical quartz analyzer for use in resonant inelastic X-ray scattering (RIXS) is introduced, achieving an unprecedented energy resolution of 10.53 meV at the IrL 3absorption edge (11.215 keV). In this work the fabrication process and the characterization of the analyzer are presented, and an example of a RIXS spectrum of magnetic excitations in a Sr 3Ir 2O 7sample is shown.

  20. X-ray ptychography

    NASA Astrophysics Data System (ADS)

    Pfeiffer, Franz

    2018-01-01

    X-ray ptychographic microscopy combines the advantages of raster scanning X-ray microscopy with the more recently developed techniques of coherent diffraction imaging. It is limited neither by the fabricational challenges associated with X-ray optics nor by the requirements of isolated specimen preparation, and offers in principle wavelength-limited resolution, as well as stable access and solution to the phase problem. In this Review, we discuss the basic principles of X-ray ptychography and summarize the main milestones in the evolution of X-ray ptychographic microscopy and tomography over the past ten years, since its first demonstration with X-rays. We also highlight the potential for applications in the life and materials sciences, and discuss the latest advanced concepts and probable future developments.

  1. Data consistency-driven scatter kernel optimization for x-ray cone-beam CT

    NASA Astrophysics Data System (ADS)

    Kim, Changhwan; Park, Miran; Sung, Younghun; Lee, Jaehak; Choi, Jiyoung; Cho, Seungryong

    2015-08-01

    Accurate and efficient scatter correction is essential for acquisition of high-quality x-ray cone-beam CT (CBCT) images for various applications. This study was conducted to demonstrate the feasibility of using the data consistency condition (DCC) as a criterion for scatter kernel optimization in scatter deconvolution methods in CBCT. As in CBCT, data consistency in the mid-plane is primarily challenged by scatter, we utilized data consistency to confirm the degree of scatter correction and to steer the update in iterative kernel optimization. By means of the parallel-beam DCC via fan-parallel rebinning, we iteratively optimized the scatter kernel parameters, using a particle swarm optimization algorithm for its computational efficiency and excellent convergence. The proposed method was validated by a simulation study using the XCAT numerical phantom and also by experimental studies using the ACS head phantom and the pelvic part of the Rando phantom. The results showed that the proposed method can effectively improve the accuracy of deconvolution-based scatter correction. Quantitative assessments of image quality parameters such as contrast and structure similarity (SSIM) revealed that the optimally selected scatter kernel improves the contrast of scatter-free images by up to 99.5%, 94.4%, and 84.4%, and of the SSIM in an XCAT study, an ACS head phantom study, and a pelvis phantom study by up to 96.7%, 90.5%, and 87.8%, respectively. The proposed method can achieve accurate and efficient scatter correction from a single cone-beam scan without need of any auxiliary hardware or additional experimentation.

  2. Geometry of Pt(IV) in H 2PtCl 6 aqueous solution: An X-ray absorption spectroscopic investigation

    NASA Astrophysics Data System (ADS)

    Chen, Xing; Chu, Wangsheng; Wang, Lei; Wu, Ziyu

    2009-02-01

    The noble metal ions play an important role in many chemical reactions, but at the present time they represent also potentially new environmental contaminants. There is relatively little information available to adequately assess the potential health hazards, so that to evaluate the potential hazards and identify the necessary actions to reduce the risks associated with exposure to these metals and their compounds it is important to understand the local structure around noble metal ions. In this contribution, the local coordination around platinum (IV) ions e.g., Pt 4+ in aqueous solution, has been investigated by using X-ray absorption spectroscopy (XAS). X-ray absorption near-edge spectra (XANES) of both [PtCl 6] 2- and [PtCl 4(OH) 2] 2- in an aqueous solution have been calculated using FEFF8.2 and both are characterized by an octahedral geometry. From these calculations, we may also assign a characteristic post-edge feature to a contribution of Cl d-states. From the EXAFS analysis we also determined the corresponding Pt bond distances, e.g., 2.33 Å for the Pt-Cl distance and 2.03 Å for the Pt-O distance in these aqueous solutions. The same analysis provides evidence that the peaks in the Fourier transform at about 4.0 Å are due to multiple scattering collinear Cl-Pt-Cl contributions.

  3. X-ray near-field speckle: implementation and critical analysis

    PubMed Central

    Lu, Xinhui; Mochrie, S. G. J.; Narayanan, S.; Sandy, A. R.; Sprung, M.

    2011-01-01

    The newly introduced coherence-based technique of X-ray near-field speckle (XNFS) has been implemented at 8-ID-I at the Advanced Photon Source. In the near-field regime of high-brilliance synchrotron X-rays scattered from a sample of interest, it turns out that, when the scattered radiation and the main beam both impinge upon an X-ray area detector, the measured intensity shows low-contrast speckles, resulting from interference between the incident and scattered beams. A micrometer-resolution XNFS detector with a high numerical aperture microscope objective has been built and its capability for studying static structures and dynamics at longer length scales than traditional far-field X-ray scattering techniques is demonstrated. Specifically, the dynamics of dilute silica and polystyrene colloidal samples are characterized. This study reveals certain limitations of the XNFS technique, especially in the characterization of static structures, which is discussed. PMID:21997906

  4. X-ray scatter imaging of hepatocellular carcinoma in a mouse model using nanoparticle contrast agents

    DOE PAGES

    Rand, Danielle; Derdak, Zoltan; Carlson, Rolf; ...

    2015-10-29

    Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide and is almost uniformly fatal. Current methods of detection include ultrasound examination and imaging by CT scan or MRI; however, these techniques are problematic in terms of sensitivity and specificity, and the detection of early tumors (<1 cm diameter) has proven elusive. Better, more specific, and more sensitive detection methods are therefore urgently needed. Here we discuss the application of a newly developed x-ray imaging technique called Spatial Frequency Heterodyne Imaging (SFHI) for the early detection of HCC. SFHI uses x-rays scattered by an object to form anmore » image and is more sensitive than conventional absorption-based x-radiography. We show that tissues labeled in vivo with gold nanoparticle contrast agents can be detected using SFHI. We also demonstrate that directed targeting and SFHI of HCC tumors in a mouse model is possible through the use of HCC-specific antibodies. As a result, the enhanced sensitivity of SFHI relative to currently available techniques enables the x-ray imaging of tumors that are just a few millimeters in diameter and substantially reduces the amount of nanoparticle contrast agent required for intravenous injection relative to absorption-based x-ray imaging.« less

  5. X-ray Scatter Imaging of Hepatocellular Carcinoma in a Mouse Model Using Nanoparticle Contrast Agents

    NASA Astrophysics Data System (ADS)

    Rand, Danielle; Derdak, Zoltan; Carlson, Rolf; Wands, Jack R.; Rose-Petruck, Christoph

    2015-10-01

    Hepatocellular carcinoma (HCC) is one of the most common malignant tumors worldwide and is almost uniformly fatal. Current methods of detection include ultrasound examination and imaging by CT scan or MRI; however, these techniques are problematic in terms of sensitivity and specificity, and the detection of early tumors (<1 cm diameter) has proven elusive. Better, more specific, and more sensitive detection methods are therefore urgently needed. Here we discuss the application of a newly developed x-ray imaging technique called Spatial Frequency Heterodyne Imaging (SFHI) for the early detection of HCC. SFHI uses x-rays scattered by an object to form an image and is more sensitive than conventional absorption-based x-radiography. We show that tissues labeled in vivo with gold nanoparticle contrast agents can be detected using SFHI. We also demonstrate that directed targeting and SFHI of HCC tumors in a mouse model is possible through the use of HCC-specific antibodies. The enhanced sensitivity of SFHI relative to currently available techniques enables the x-ray imaging of tumors that are just a few millimeters in diameter and substantially reduces the amount of nanoparticle contrast agent required for intravenous injection relative to absorption-based x-ray imaging.

  6. Robust X-ray angular correlations for the study of meso-structures

    DOE PAGES

    Lhermitte, Julien R.; Tian, Cheng; Stein, Aaron; ...

    2017-05-08

    As self-assembling nanomaterials become more sophisticated, it is becoming increasingly important to measure the structural order of finite-sized assemblies of nano-objects. These mesoscale clusters represent an acute challenge to conventional structural probes, owing to the range of implicated size scales (10 nm to several micrometres), the weak scattering signal and the dynamic nature of meso-clusters in native solution environments. The high X-ray flux and coherence of modern synchrotrons present an opportunity to extract structural information from these challenging systems, but conventional ensemble X-ray scattering averages out crucial information about local particle configurations. Conversely, a single meso-cluster scatters too weakly tomore » recover the full diffraction pattern. Using X-ray angular cross-correlation analysis, it is possible to combine multiple noisy measurements to obtain robust structural information. This paper explores the key theoretical limits and experimental challenges that constrain the application of these methods to probing structural order in real nanomaterials. A metric is presented to quantify the signal-to-noise ratio of angular correlations, and it is used to identify several experimental artifacts that arise. In particular, it is found that background scattering, data masking and inter-cluster interference profoundly affect the quality of correlation analyses. A robust workflow is demonstrated for mitigating these effects and extracting reliable angular correlations from realistic experimental data.« less

  7. Bent crystal spectrometer for both frequency and wavenumber resolved x-ray scattering at a seeded free-electron laser.

    PubMed

    Zastrau, Ulf; Fletcher, Luke B; Förster, Eckhart; Galtier, Eric Ch; Gamboa, Eliseo; Glenzer, Siegfried H; Heimann, Philipp; Marschner, Heike; Nagler, Bob; Schropp, Andreas; Wehrhan, Ortrud; Lee, Hae Ja

    2014-09-01

    We present a cylindrically curved GaAs x-ray spectrometer with energy resolution ΔE/E = 1.1 × 10(-4) and wave-number resolution of Δk/k = 3 × 10(-3), allowing plasmon scattering at the resolution limits of the Linac Coherent Light Source (LCLS) x-ray free-electron laser. It spans scattering wavenumbers of 3.6 to 5.2/Å in 100 separate bins, with only 0.34% wavenumber blurring. The dispersion of 0.418 eV/13.5 μm agrees with predictions within 1.3%. The reflection homogeneity over the entire wavenumber range was measured and used to normalize the amplitude of scattering spectra. The proposed spectrometer is superior to a mosaic highly annealed pyrolytic graphite spectrometer when the energy resolution needs to be comparable to the LCLS seeded bandwidth of 1 eV and a significant range of wavenumbers must be covered in one exposure.

  8. Design and performance of BOREAS, the beamline for resonant X-ray absorption and scattering experiments at the ALBA synchrotron light source

    DOE PAGES

    Barla, Alessandro; Nicolas, Josep; Cocco, Daniele; ...

    2016-10-07

    The optical design of the BOREAS beamline operating at the ALBA synchrotron radiation facility is described. BOREAS is dedicated to resonant X-ray absorption and scattering experiments using soft X-rays, in an unusually extended photon energy range from 80 to above 4000 eV, and with full polarization control. Its optical scheme includes a fixed-included-angle, variable-line-spacing grating monochromator and a pair of refocusing mirrors, equipped with benders, in a Kirkpatrick–Baez arrangement. It is equipped with two end-stations, one for X-ray magnetic circular dichroism and the other for resonant magnetic scattering. In conclusion, the commissioning results show that the expected beamline performance ismore » achieved both in terms of energy resolution and of photon flux at the sample position.« less

  9. Influence of argon impurities on the elastic scattering of x-rays from imploding beryllium capsules

    NASA Astrophysics Data System (ADS)

    Saunders, A. M.; Chapman, D. A.; Kritcher, A. L.; Schoff, M.; Shuldberg, C.; Landen, O. L.; Glenzer, S. H.; Falcone, R. W.; Gericke, D. O.; Döppner, T.

    2018-03-01

    We investigate the effect of argon impurities on the elastic component of x-ray scattering spectra taken from directly driven beryllium capsule implosions at the OMEGA laser. The plasma conditions were obtained in a previous analysis [18] by fitting the inelastic scattering component. We show that the known argon impurity in the beryllium modifies the elastic scattering due to the larger number of bound electrons. We indeed find significant deviations in the elastic scattering from roughly 1 at.% argon contained in the beryllium. With knowledge of the argon impurity fraction, we use the elastic scattering component to determine the charge state of the compressed beryllium, as the fits are rather insensitive to the argon charge state. Finally, we discuss how doping small fractions of mid- or high-Z elements into low-Z materials could allow ionization balance studies in dense plasmas.

  10. Diagnostic X-ray sources-present and future

    NASA Astrophysics Data System (ADS)

    Behling, Rolf; Grüner, Florian

    2018-01-01

    This paper compares very different physical principles of X-ray production to spur ideation. Since more than 120 years, bremsstrahlung from X-ray tubes has been the workhorse of medical diagnostics. Generated by X-ray segments comprised of X-ray tubes and high-voltage generators in the various medical systems, X-ray photons in the spectral range between about 16 keV and 150 keV deliver information about anatomy and function of human patients and in pre-clinical animal studies. Despite of strides to employ the wave nature of X-rays as phase sensitive means, commercial diagnostic X-ray systems available until the time of writing still rely exclusively on measuring the attenuation and scattering of X-rays by matter. Significant activities in research aim at building highly brilliant short pulse X-ray sources, based on e.g. synchrotron radiation, free electron lasers and/or laser wake-field acceleration of electrons followed by wiggling with magnetic structures or Thomson scattering in bunches of light. While both approaches, non-brilliant and brilliant sources, have different scope of application, we speculate that a combination may expand the efficacy in medical application. At this point, however, severe technical and commercial difficulties hinder closing this gap. This article may inspire further development and spark innovation in this important field.

  11. Quantum theory for the dynamic structure factor in correlated two-component systems in nonequilibrium: Application to x-ray scattering.

    PubMed

    Vorberger, J; Chapman, D A

    2018-01-01

    We present a quantum theory for the dynamic structure factors in nonequilibrium, correlated, two-component systems such as plasmas or warm dense matter. The polarization function, which is needed as the input for the calculation of the structure factors, is calculated in nonequilibrium based on a perturbation expansion in the interaction strength. To make our theory applicable for x-ray scattering, a generalized Chihara decomposition for the total electron structure factor in nonequilibrium is derived. Examples are given and the influence of correlations and exchange on the structure and the x-ray-scattering spectrum are discussed for a model nonequilibrium distribution, as often encountered during laser heating of materials, as well as for two-temperature systems.

  12. Quantum theory for the dynamic structure factor in correlated two-component systems in nonequilibrium: Application to x-ray scattering

    NASA Astrophysics Data System (ADS)

    Vorberger, J.; Chapman, D. A.

    2018-01-01

    We present a quantum theory for the dynamic structure factors in nonequilibrium, correlated, two-component systems such as plasmas or warm dense matter. The polarization function, which is needed as the input for the calculation of the structure factors, is calculated in nonequilibrium based on a perturbation expansion in the interaction strength. To make our theory applicable for x-ray scattering, a generalized Chihara decomposition for the total electron structure factor in nonequilibrium is derived. Examples are given and the influence of correlations and exchange on the structure and the x-ray-scattering spectrum are discussed for a model nonequilibrium distribution, as often encountered during laser heating of materials, as well as for two-temperature systems.

  13. Report on the 18th International Conference on X-ray and Inner-Shell Processes (X99).

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gemmell, D. S.; Physics

    2000-01-01

    The 18th conference of the series served as a forum for discussing fundamental issues in the field of x-ray and inner-shell processes and their application in various disciplines of science and technology. Special emphasis was given to the opportunities offered by modern synchrotron x-ray sources. The program included plenary talks, progress reports and poster presentations relating to new developments in the field of x-ray and inner-shell processes. The range of topics included: X-ray interactions with atoms, molecules, clusters, surfaces and solids; Decay processes for inner-shell vacancies; X-ray absorption and emission spectroscopy - Photoionization processes; Phenomena associated with highly charged ionsmore » and collisions with energetic particles; Electron-spin and -momentum spectroscopy; X-ray scattering and spectroscopy in the study of magnetic systems; Applications in materials science, biology, geosciences, and other disciplines; Elastic and inelastic x-ray scattering processes in atoms and molecules; Threshold phenomena (post-collision interaction, resonant Raman processes, etc.); Nuclear absorption and scattering of x-rays; 'Fourth-generation' x-ray sources; Processes exploiting the polarization and coherence properties of x-ray beams; Developments in experimental techniques (x-ray optics, temporal techniques, detectors); Microscopy, spectromicroscopy, and various imaging techniques; Non-linear processes and x-ray lasers; Ionization and excitation induced by charged particles and by x-rays; and Exotic atoms (including 'hollow' atoms and atoms that contain 'exotic' particles).« less

  14. Development of ultrahigh-resolution inelastic x-ray scattering optics

    NASA Astrophysics Data System (ADS)

    Huang, Xian-Rong; Zhong, Zhong; Cai, Yong Q.; Coburn, S.

    2008-08-01

    One of the major goals of the National Synchrotron Light Source II project is to achieve ultrahigh energy resolution up to 0.1 meV for medium-energy inelastic X-ray scattering spectroscopy based on the angular dispersion optics employing extremely asymmetric backscattering geometry. In this papaer, we describe the complete monochromatization mechanisms underlying the new optics. We have also designed and tested a CDW-CDW prototype under ambient condition, with which we have successfully demonstrated the important angular dispersion effect, the Borrman enhanced transmission effect, and other optical principles involved in every step of the entire diffraction process, and found good agreement with the theoretical expectations. These studies indicate that the new optics are feasible in principle but face some technical challenges that need to be solved by our future systematic research and development activities before their practical applications.

  15. X-ray scattering measurements of strong ion-ion correlations in shock-compressed aluminum.

    PubMed

    Ma, T; Döppner, T; Falcone, R W; Fletcher, L; Fortmann, C; Gericke, D O; Landen, O L; Lee, H J; Pak, A; Vorberger, J; Wünsch, K; Glenzer, S H

    2013-02-08

    The strong ion-ion correlation peak characteristic of warm dense matter (WDM) is observed for the first time using simultaneous angularly, temporally, and spectrally resolved x-ray scattering measurements in laser-driven shock-compressed aluminum. Laser-produced molybdenum x-ray line emission at an energy of 17.9 keV is employed to probe aluminum compressed to a density of ρ>8 g/cm(3). We observe a well pronounced peak in the static structure factor at a wave number of k=4.0 Å(-1). The measurements of the magnitude and position of this correlation peak are precise enough to test different theoretical models for the ion structure and show that only models taking the complex interaction in WDM into account agree with the data. This also demonstrates a new highly accurate diagnostic to directly measure the state of compression of warm dense matter.

  16. Inverse Compton Scattered Merger-nova: Late X-Ray Counterpart of Gravitational-wave Signals from NS–NS/BH Mergers

    NASA Astrophysics Data System (ADS)

    Ai, Shunke; Gao, He

    2018-01-01

    The recent observations of GW170817 and its electromagnetic (EM) counterparts show that double neutron star mergers could lead to rich and bright EM emissions. Recent numerical simulations suggest that neutron star and neutron star/black hole (NS–NS/BH) mergers would leave behind a central remnant surrounded by a mildly isotropic ejecta. The central remnant could launch a collimated jet and when the jet propagates through the ejecta, a mildly relativistic cocoon would be formed and the interaction between the cocoon and the ambient medium would accelerate electrons via external shock in a wide angle, so that the merger-nova photons (i.e., thermal emission from the ejecta) would be scattered into higher frequency via an inverse Compton (IC) process when they propagate through the cocoon shocked region. We find that the IC scattered component peaks at the X-ray band and it will reach its peak luminosity on the order of days (simultaneously with the merger-nova emission). With current X-ray detectors, such a late X-ray component could be detected out to 200 Mpc, depending on the merger remnant properties. It could serve as an important electromagnetic counterpart of gravitational-wave signals from NS–NS/BH mergers. Nevertheless, simultaneous detection of such a late X-ray signal and the merger-nova signal could shed light on the cocoon properties and the concrete structure of the jet.

  17. Liquid Dynamics in high melting materials studied by inelastic X-ray scattering

    NASA Astrophysics Data System (ADS)

    Sinn, Harald; Alatas, Ahmet; Said, Ayman; Alp, Esen E.; Price, David L.; Saboungi, Marie Louis; Scheunemann, Richard

    2004-03-01

    The transport properties of high melting materials are of interest for a variety of applications, including geo-sciences, nuclear waste confinement and aerospace technology. While traditional methods of measuring transport properties are often extremely difficult due to the high reactivity of the melts, the combination of containerless levitation and inelastic X-ray scattering offers new insights in the microscopic dynamics of these liquids. Data on the dynamic structure factor of liquid aluminum oxide and liquid boron between 2000-2800 degree Celsius are discussed and related to several macroscopic quantities like sound velocity, viscosity and diffusion.

  18. Pair distribution functions of amorphous organic thin films from synchrotron X-ray scattering in transmission mode

    DOE PAGES

    Shi, Chenyang; Teerakapibal, Rattavut; Yu, Lian; ...

    2017-07-10

    Using high-brilliance high-energy synchrotron X-ray radiation, for the first time the total scattering of a thin organic glass film deposited on a strongly scattering inorganic substrate has been measured in transmission mode. The organic thin film was composed of the weakly scattering pharmaceutical substance indomethacin in the amorphous state. The film was 130 µm thick atop a borosilicate glass substrate of equal thickness. The atomic pair distribution function derived from the thin-film measurement is in excellent agreement with that from bulk measurements. This ability to measure the total scattering of amorphous organic thin films in transmission will enable accurate in situmore » structural studies for a wide range of materials.« less

  19. Pair distribution functions of amorphous organic thin films from synchrotron X-ray scattering in transmission mode

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shi, Chenyang; Teerakapibal, Rattavut; Yu, Lian

    2017-07-10

    Using high-brilliance high-energy synchrotron X-ray radiation, for the first time the total scattering of a thin organic glass film deposited on a strongly scattering inorganic substrate has been measured in transmission mode. The organic thin film was composed of the weakly scattering pharmaceutical substance indomethacin in the amorphous state. The film was 130 µm thick atop a borosilicate glass substrate of equal thickness. The atomic pair distribution function derived from the thin-film measurement is in excellent agreement with that from bulk measurements. This ability to measure the total scattering of amorphous organic thin films in transmission will enable accuratein situstructuralmore » studies for a wide range of materials.« less

  20. Revealing the electronic ground state of ReNiO3 combining Ni-L3 x-ray absorption and resonant inelastic x-ray scattering

    NASA Astrophysics Data System (ADS)

    Bisogni, Valentina; Catalano, Sara; Green, Robert; Gibert, Marta; Scherwitzl, Raoul; Huang, Yaobo; Balandesh, Shadi; Strocov, Vladimir N.; Zubko, Pavlo; Sawatzky, George; Triscone, Jean-Marc; Schmitt, Thorsten

    Rare-earth nickelates ReNiO3 attract a lot of interest thanks to their intriguing physical properties like sharp metal to insulator transition, unusual magnetic order and expected superconductivity in nickelate-based heterostructures. Full understanding of these materials, however, is hampered by the difficulties in describing their electronic ground state (GS). Taking a NdNiO3 thin film as a representative example, we reveal with x-ray absorption and resonant inelastic x-ray scattering unusual coexistence of bound and continuum excitations, providing strong evidence for abundant O 2p holes in the GS of these materials. Using an Anderson impurity model interpretation, we show that these distinct spectral signatures arise from a Ni 3d8 configuration along with holes in the O 2p valence band, confirming suggestions that these materials exhibit a negative charge-transfer energy, with O 2p states extending across the Fermi level.

  1. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Swadling, G. F.; Ross, J. S.; Datte, P.

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Laboratory. This diagnostic is designed to make measurements of the hohlraum plasma parameters, such as the electron temperature and the density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature, hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimatedmore » to be ∼8 J cm{sup −2}. This is significantly above the expected threshold for the onset of “blanking” effects. A novel xenon plasma x-ray shield is proposed to protect the blast shield from x-rays and mitigate “blanking.” Estimates suggest that an areal density of 10{sup 19} cm{sup −2} Xe atoms will be sufficient to absorb 99.5% of the soft x-ray flux. Two potential designs for this shield are presented.« less

  2. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Swadling, G. F.; Ross, J. S.; Datte, P.

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Labs (LLNL). This diagnostic is designed to make measurements of hohlraum plasma parameters, such as the electron temperature and density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated tomore » be ~ 8 J cm -2. This is then significantly above the expected threshold for the onset of “blanking” effects. A novel Xenon Plasma X-ray Shield (XPXS) has been proposed to protect the blast shield from x-rays and mitigate “blanking”. Finally, these estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% the soft x-ray flux. Two potential designs for this shield are presented.« less

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

    USGS Publications Warehouse

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

    2005-01-01

    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.

  4. Design calculations for a xenon plasma x-ray shield to protect the NIF optical Thomson scattering diagnostic

    DOE PAGES

    Swadling, G. F.; Ross, J. S.; Datte, P.; ...

    2016-07-21

    An Optical Thomson Scattering (OTS) diagnostic is currently being developed for the National Ignition Facility (NIF) at Lawrence Livermore National Labs (LLNL). This diagnostic is designed to make measurements of hohlraum plasma parameters, such as the electron temperature and density, during inertial confinement fusion (ICF) experiments. NIF ICF experiments present a very challenging environment for optical measurements; by their very nature hohlraums produce intense soft x-ray emission, which can cause “blanking” (radiation induced opacity) of the radiation facing optical components. The soft x-ray fluence at the surface of the OTS blast shield, 60 cm from the hohlraum, is estimated tomore » be ~ 8 J cm -2. This is then significantly above the expected threshold for the onset of “blanking” effects. A novel Xenon Plasma X-ray Shield (XPXS) has been proposed to protect the blast shield from x-rays and mitigate “blanking”. Finally, these estimates suggest that an areal density of 10 19 cm -2 Xe atoms will be sufficient to absorb 99.5% the soft x-ray flux. Two potential designs for this shield are presented.« less

  5. Reply to Comment on X-ray resonant scattering studies of orbital and charge ordering in Pr[sub 1-x]Ca[sub x]MnO[sub 3].

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zimmermann, M. V.; Grenier, S.; Nelson, C. S.

    2003-09-01

    The interpretation given in our recent x-ray scattering study of Pr{sub 1-x}Ca{sub x}MnO{sub 3} in terms of charge and orbital ordering is questioned in the preceding Comment by Garcia and Subias. They argue that anisotropy of the charge distribution induced by local distortions gives rise to the so-called charge order reflections. In this Reply we suggest that the two different pictures are reconcilable.

  6. Direct detection of x-rays for protein crystallography employing a thick, large area CCD

    DOEpatents

    Atac, Muzaffer; McKay, Timothy

    1999-01-01

    An apparatus and method for directly determining the crystalline structure of a protein crystal. The crystal is irradiated by a finely collimated x-ray beam. The interaction of the x-ray beam with the crystal produces scattered x-rays. These scattered x-rays are detected by means of a large area, thick CCD which is capable of measuring a significant number of scattered x-rays which impact its surface. The CCD is capable of detecting the position of impact of the scattered x-ray on the surface of the CCD and the quantity of scattered x-rays which impact the same cell or pixel. This data is then processed in real-time and the processed data is outputted to produce a image of the structure of the crystal. If this crystal is a protein the molecular structure of the protein can be determined from the data received.

  7. Difference structures from time-resolved small-angle and wide-angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Nepal, Prakash; Saldin, D. K.

    2018-05-01

    Time-resolved small-angle x-ray scattering/wide-angle x-ray scattering (SAXS/WAXS) is capable of recovering difference structures directly from difference SAXS/WAXS curves. It does so by means of the theory described here because the structural changes in pump-probe detection in a typical time-resolved experiment are generally small enough to be confined to a single residue or group in close proximity which is identified by a method akin to the difference Fourier method of time-resolved crystallography. If it is assumed, as is usual with time-resolved structures, that the moved atoms lie within the residue, the 100-fold reduction in the search space (assuming a typical protein has about 100 residues) allows the exaction of the structure by a simulated annealing algorithm with a huge reduction in computing time and leads to a greater resolution by varying the positions of atoms only within that residue. This reduction in the number of potential moved atoms allows us to identify the actual motions of the individual atoms. In the case of a crystal, time-resolved calculations are normally performed using the difference Fourier method, which is, of course, not directly applicable to SAXS/WAXS. The method developed in this paper may be thought of as a substitute for that method which allows SAXS/WAXS (and hence disordered molecules) to also be used for time-resolved structural work.

  8. Proton-induced x-ray fluorescence CT imaging

    PubMed Central

    Bazalova-Carter, Magdalena; Ahmad, Moiz; Matsuura, Taeko; Takao, Seishin; Matsuo, Yuto; Fahrig, Rebecca; Shirato, Hiroki; Umegaki, Kikuo; Xing, Lei

    2015-01-01

    Purpose: To demonstrate the feasibility of proton-induced x-ray fluorescence CT (pXFCT) imaging of gold in a small animal sized object by means of experiments and Monte Carlo (MC) simulations. Methods: First, proton-induced gold x-ray fluorescence (pXRF) was measured as a function of gold concentration. Vials of 2.2 cm in diameter filled with 0%–5% Au solutions were irradiated with a 220 MeV proton beam and x-ray fluorescence induced by the interaction of protons, and Au was detected with a 3 × 3 mm2 CdTe detector placed at 90° with respect to the incident proton beam at a distance of 45 cm from the vials. Second, a 7-cm diameter water phantom containing three 2.2-diameter vials with 3%–5% Au solutions was imaged with a 7-mm FWHM 220 MeV proton beam in a first generation CT scanning geometry. X-rays scattered perpendicular to the incident proton beam were acquired with the CdTe detector placed at 45 cm from the phantom positioned on a translation/rotation stage. Twenty one translational steps spaced by 3 mm at each of 36 projection angles spaced by 10° were acquired, and pXFCT images of the phantom were reconstructed with filtered back projection. A simplified geometry of the experimental data acquisition setup was modeled with the MC TOPAS code, and simulation results were compared to the experimental data. Results: A linear relationship between gold pXRF and gold concentration was observed in both experimental and MC simulation data (R2 > 0.99). All Au vials were apparent in the experimental and simulated pXFCT images. Specifically, the 3% Au vial was detectable in the experimental [contrast-to-noise ratio (CNR) = 5.8] and simulated (CNR = 11.5) pXFCT image. Due to fluorescence x-ray attenuation in the higher concentration vials, the 4% and 5% Au contrast were underestimated by 10% and 15%, respectively, in both the experimental and simulated pXFCT images. Conclusions: Proton-induced x-ray fluorescence CT imaging of 3%–5% gold solutions in a small animal

  9. Time resolved small angle X-ray scattering experiments performed on detonating explosives at the advanced photon source: Calculation of the time and distance between the detonation front and the x-ray beam

    DOE PAGES

    Gustavsen, Richard L.; Dattelbaum, Dana Mcgraw; Watkins, Erik Benjamin; ...

    2017-03-10

    Time resolved Small Angle X-ray Scattering (SAXS) experiments on detonating explosives have been conducted at Argonne National Laboratory's Advanced Photon Source Dynamic Compression Sector. The purpose of the experiments is to measure the SAXS patterns at tens of ns to a few μs behind the detonation front. Corresponding positions behind the detonation front are of order 0.1–10 mm. From the scattering patterns, properties of the explosive products relative to the time behind the detonation front can be inferred. Lastly, this report describes how the time and distance from the x-ray probe location to the detonation front is calculated, as wellmore » as the uncertainties and sources of uncertainty associated with the calculated times and distances.« less

  10. Time resolved small angle X-ray scattering experiments performed on detonating explosives at the advanced photon source: Calculation of the time and distance between the detonation front and the x-ray beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gustavsen, Richard L.; Dattelbaum, Dana Mcgraw; Watkins, Erik Benjamin

    Time resolved Small Angle X-ray Scattering (SAXS) experiments on detonating explosives have been conducted at Argonne National Laboratory's Advanced Photon Source Dynamic Compression Sector. The purpose of the experiments is to measure the SAXS patterns at tens of ns to a few μs behind the detonation front. Corresponding positions behind the detonation front are of order 0.1–10 mm. From the scattering patterns, properties of the explosive products relative to the time behind the detonation front can be inferred. Lastly, this report describes how the time and distance from the x-ray probe location to the detonation front is calculated, as wellmore » as the uncertainties and sources of uncertainty associated with the calculated times and distances.« less

  11. On the possibility of using X-ray Compton scattering to study magnetoelectrical properties of crystals

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Collins, S. P., E-mail: steve.collins@diamond.ac.uk; Laundy, D.; Connolley, T.

    2016-02-16

    The possibility of using X-ray Compton scattering to reveal antisymmetric components of the electron momentum density, as a fingerprint of magnetoelectric sample properties, is investigated experimentally and theoretically by studying the polar ferromagnet GaFeO{sub 3}. This paper discusses the possibility of using Compton scattering – an inelastic X-ray scattering process that yields a projection of the electron momentum density – to probe magnetoelectrical properties. It is shown that an antisymmetric component of the momentum density is a unique fingerprint of such time- and parity-odd physics. It is argued that polar ferromagnets are ideal candidates to demonstrate this phenomenon and themore » first experimental results are shown, on a single-domain crystal of GaFeO{sub 3}. The measured antisymmetric Compton profile is very small (≃ 10{sup −5} of the symmetric part) and of the same order of magnitude as the statistical errors. Relativistic first-principles simulations of the antisymmetric Compton profile are presented and it is shown that, while the effect is indeed predicted by theory, and scales with the size of the valence spin–orbit interaction, its magnitude is significantly overestimated. The paper outlines some important constraints on the properties of the antisymmetric Compton profile arising from the underlying crystallographic symmetry of the sample.« less

  12. Influence of argon impurities on the elastic scattering of x-rays from imploding beryllium capsules

    DOE PAGES

    Saunders, A. M.; Chapman, D. A.; Kritcher, A. L.; ...

    2018-03-01

    Here, we investigate the effect of argon impurities on the elastic component of x-ray scattering spectra taken from directly driven beryllium capsule implosions at the OMEGA laser. The plasma conditions were obtained in a previous analysis [18] by fitting the inelastic scattering component. We show that the known argon impurity in the beryllium modifies the elastic scattering due to the larger number of bound electrons. We indeed find significant deviations in the elastic scattering from roughly 1 at.% argon contained in the beryllium. With knowledge of the argon impurity fraction, we use the elastic scattering component to determine the chargemore » state of the compressed beryllium, as the fits are rather insensitive to the argon charge state. Lastly, we discuss how doping small fractions of mid- or high-Z elements into low-Z materials could allow ionization balance studies in dense plasmas.« less

  13. Metal-ligand Covalency of Iron Complexes from High-Resolution Resonant Inelastic X-ray Scattering

    PubMed Central

    Lundberg, Marcus; Kroll, Thomas; DeBeer, Serena; Bergmann, Uwe; Wilson, Samuel A.; Glatzel, Pieter; Nordlund, Dennis; Hedman, Britt; Hodgson, Keith O.; Solomon, Edward I.

    2013-01-01

    Data from Kα resonant inelastic X-ray scattering (RIXS) have been used to extract electronic structure information, i.e., the covalency of metal-ligand bonds, for four iron complexes using an experimentally based theoretical model. Kα RIXS involves resonant 1s → 3d excitation and detection of the 2p → 1s (Kα) emission. This two-photon process reaches similar final states as single-photon L-edge (2p → 3d) X-ray absorption spectroscopy (XAS), but involves only hard X-rays and can therefore be used to get high-resolution L-edge-like spectra for metal proteins, solution catalysts and their intermediates. To analyze the information content of Kα RIXS spectra, data have been collected for four characteristic σ-donor and π-backdonation complexes; ferrous tacn [FeII(tacn)2]Br2, ferrocyanide [FeII(CN)6]K4, ferric tacn [FeIII(tacn)2]Br3 and ferricyanide [FeIII(CN)6]K3. From these spectra metal-ligand covalencies can be extracted using a charge-transfer multiplet model, without previous information from the L-edge XAS experiment. A direct comparison of L-edge XAS and Kα RIXS spectra show that the latter reaches additional final states, e.g., when exciting into the eg (σ*) orbitals, and the splitting between final states of different symmetry provides an extra dimension that makes Kα RIXS a more sensitive probe of σ-bonding. Another key difference between L-edge XAS and Kα RIXS is the π-backbonding features in ferro- and ferricyanide that are significantly more intense in L-edge XAS compared to Kα RIXS. This shows that two methods are complimentary in assigning electronic structure. The Kα RIXS approach can thus be used as a stand-alone method, in combination with L-edge XAS for strongly covalent systems that are difficult to probe by UV/Vis spectroscopy, or as an extension to conventional absorption spectroscopy for a wide range of transition metal enzymes and catalysts. PMID:24131028

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

    PubMed

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

    2013-01-01

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

  15. X-Ray Dust Tomography: Mapping the Galaxy one X-ray Transient at a Time

    NASA Astrophysics Data System (ADS)

    Heinz, Sebastian; Corrales, Lia

    2018-01-01

    Tomography using X-ray light echoes from dust scattering by interstellar clouds is an accurate tool to study the line-of-sight distribution of dust. It can be used to measure distances to molecular clouds and X-ray sources, it can map Galactic structure in dust, and it can be used for precision measurements of dust composition and grain size distribution. Necessary conditions for observing echoes include a suitable X-ray lightcurve and sufficient dust column density to the source. I will discuss a tool set for studying dust echoes and show results obtained for some of the brightest echoes detected to date.

  16. Determination of the topological shape of integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria in the detergent solution by small-angle X-ray scattering.

    PubMed

    Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

    2004-02-01

    The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 A, a long axis of 110 A, and a short axis of 85 A. After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 A, a long axis of 80 A, and a short axis of 55 A. In contrast to the cylindrical crystal structure with a height of 40 A and a diameter of 68 A, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59-consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules.

  17. Determination of the Topological Shape of Integral Membrane Protein Light-Harvesting Complex LH2 from Photosynthetic Bacteria in the Detergent Solution by Small-Angle X-Ray Scattering

    PubMed Central

    Hong, Xinguo; Weng, Yu-Xiang; Li, Ming

    2004-01-01

    The topological shape of the integral membrane protein light-harvesting complex LH2 from photosynthetic bacteria Rhodobacter spheroides 2.4.1 in detergent solution has been determined from synchrotron small-angle X-ray scattering data using direct curve-fitting by the ellipsoid, ab initio shape determination methods of simulated annealing algorithm and multipole expansion, respectively. The results indicate that the LH2 protein in aqueous solution is encapsulated by a monolayered detergent shell. The detergent-stabilized structure has the shape of an oblate plate, with a thickness of 40 Å, a long axis of 110 Å, and a short axis of 85 Å . After correction for the detergent shell, the shape of the LH2 core is also an oblate plate with a height of 40 Å, a long axis of 80 Å, and a short axis of 55 Å. In contrast to the cylindrical crystal structure with a height of 40 Å and a diameter of 68 Å, the molecular shape of the LH2 complex in detergent solution clearly deviates from the ringlike crystal structure, with an eccentricity found to be 0.59—consistent with the result of single molecular spectroscopy study of the isolated single LH2 molecules. PMID:14747343

  18. Spectrum bandwidth narrowing of Thomson scattering X-rays with energy chirped electron beams from laser wakefield acceleration

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xu, Tong; Chen, Min, E-mail: minchen@sjtu.edu.cn; Li, Fei-Yu

    2014-01-06

    We study incoherent Thomson scattering between an ultrashort laser pulse and an electron beam accelerated from a laser wakefield. The energy chirp effects of the accelerated electron beam on the final radiation spectrum bandwidth are investigated. It is found that the scattered X-ray radiation has the minimum spectrum width and highest intensity as electrons are accelerated up to around the dephasing point. Furthermore, it is proposed that the electron acceleration process inside the wakefield can be studied by use of 90° Thomson scattering. The dephasing position and beam energy chirp can be deduced from the intensity and bandwidth of themore » scattered radiation.« less

  19. Neutron and x-ray scattering study of phonon dispersion and diffuse scattering in ( Na , Bi ) Ti O 3 - x BaTi O 3 single crystals near the morphotropic phase boundary

    DOE PAGES

    Luo, Chengtao; Bansal, Dipanshu; Li, Jiefang; ...

    2017-11-10

    Neutron and x-ray scattering measurements were performed on (Na 1/2Bi 1/2)TiO 3-x at % BaTiO 3 (NBT-xBT) single crystals (x = 4, 5, 6.5, and 7.5) across the morphotropic phase boundary (MPB), as a function of both composition and temperature, and probing both structural and dynamical aspects. In addition to the known diffuse scattering pattern near the gamma points, our measurements revealed new, faint superlattice peaks, as well as an extensive diffuse scattering network, revealing a short-range ordering of polar nanoregions (PNR) with a static stacking morphology. Furthermore, in samples with compositions closest to the MPB, our inelastic neutron scatteringmore » investigations of the phonon dynamics showed two unusual features in the acoustic phonon branches, between the superlattice points, and between the superlattice points and gamma points, respectively. Finally, these critical elements are not present in the other compositions away from the MPB, which suggests that these features may be related to the tilt modes coupling behavior near the MPB.« less

  20. Neutron and x-ray scattering study of phonon dispersion and diffuse scattering in ( Na , Bi ) Ti O 3 - x BaTi O 3 single crystals near the morphotropic phase boundary

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Luo, Chengtao; Bansal, Dipanshu; Li, Jiefang

    Neutron and x-ray scattering measurements were performed on (Na 1/2Bi 1/2)TiO 3-x at % BaTiO 3 (NBT-xBT) single crystals (x = 4, 5, 6.5, and 7.5) across the morphotropic phase boundary (MPB), as a function of both composition and temperature, and probing both structural and dynamical aspects. In addition to the known diffuse scattering pattern near the gamma points, our measurements revealed new, faint superlattice peaks, as well as an extensive diffuse scattering network, revealing a short-range ordering of polar nanoregions (PNR) with a static stacking morphology. Furthermore, in samples with compositions closest to the MPB, our inelastic neutron scatteringmore » investigations of the phonon dynamics showed two unusual features in the acoustic phonon branches, between the superlattice points, and between the superlattice points and gamma points, respectively. Finally, these critical elements are not present in the other compositions away from the MPB, which suggests that these features may be related to the tilt modes coupling behavior near the MPB.« less

  1. Resonant inelastic X-ray scattering on synthetic nickel compounds and Ni-Fe hydrogenase protein

    NASA Astrophysics Data System (ADS)

    Sanganas, Oliver; Löscher, Simone; Pfirrmann, Stefan; Marinos, Nicolas; Glatzel, Pieter; Weng, Tsu-Chien; Limberg, Christian; Driess, Matthias; Dau, Holger; Haumann, Michael

    2009-11-01

    Ni-Fe hydrogenases are proteins catalyzing the oxidative cleavage of dihydrogen (H2) and proton reduction to H2 at high turnover rates. Their active site is a heterobimetallic center comprising one Ni and one Fe atom. To understand the function of the site, well resolved structural and electronic information is required. Such information is expected to become accessible by high resolution X-ray absorption and emission techniques, which are rapidly developing at third generation synchrotron radiation sources. We studied a number of synthetic Ni compounds, which mimic relevant features of the Ni site in hydrogenases, and the Ni site in the soluble, NAD-reducing hydrogenase (SH) from the bacterium Ralstonia eutropha by resonant inelastic X-ray scattering (RIXS) using a Rowland-type spectrometer at the ESRF. The SH is particularly interesting because its H2-cleavage reaction is highly resistant against inhibition by O2. Kα-fluorescence detected RIXS planes in the 1s→3d region of the X-ray absorption spectrum were recorded on the protein which allow to extract L3-edge type spectra Spectral features of the protein are compared to those of the model compounds.

  2. Synchrotron X-ray Scattering from Self-organized Soft Nanostructures in Clays

    NASA Astrophysics Data System (ADS)

    Fossum, J. O.

    2009-04-01

    . Gog, C. Venkataraman, Observations of orientational ordering in aqueous suspensions of a nano-layered silicate, ENERGY The International Journal 30, 873 (2005). 2. D. M. Fonseca, Y. Méheust, J. O. Fossum, K. D. Knudsen, K. J. Måløy and K. P. S. Parmar, Phase behavior of platelet-shaped nanosilicate colloids in saline solutions: A small-angle X-ray scattering study J. Appl. Cryst. 40 292 (2007) 3. E. N. de Azevedo, M. Engelsberg, J. O. Fossum, R. E. de Souza, Anisotropic water diffusion in nematic self-assemblies of clay nano-platelets suspended in water, Langmuir 23, 5100 (2007) 4. Nils Ivar Ringdal, Master thesis, Department of Physics, NTNU (2008) 5. J.O. Fossum, Y. Meheust, K.P.S. Parmar, K.D. Knudsen, K.J. Maloy, D.d.M. Fonseca, Intercalation-enhanced electric polarization and chain formation of nano-layered particles, Europhys. Lett., 74, 438 (2006), and in the Scientific Highlights 2006 of the European Synchrotron Radiation Facility - ESRF (2007) 6. K.P.S. Parmar, Y. Meheust, B. Schelderupsen and J.O. Fossum, Electrorheological suspensions of laponite in oil: rheometry studies, Langmuir 24,1814 (2008) 7. F. Bergaya, B. K. G. Theng, and G. Lagaly, editors. Handbook of Clay Science. Elsevier (2006)

  3. Disentangling Transient Charge Density and Metal–Ligand Covalency in Photoexcited Ferricyanide with Femtosecond Resonant Inelastic Soft X-ray Scattering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jay, Raphael M.; Norell, Jesper; Eckert, Sebastian

    Soft X-ray spectroscopies are ideal probes of the local valence electronic structure of photocatalytically active metal sites. Here, we apply the selectivity of time-resolved resonant inelastic X-ray scattering at the iron L-edge to the transient charge distribution of an optically excited charge-transfer state in aqueous ferricyanide. Through comparison to steady-state spectra and quantum chemical calculations, the coupled effects of valence-shell closing and ligand-hole creation are experimentally and theoretically disentangled and described in terms of orbital occupancy, metal–ligand covalency, and ligand field splitting, thereby extending established steady-state concepts to the excited-state domain. π-Back-donation is found to be mainly determined by themore » metal site occupation, whereas the ligand hole instead influences σ-donation. Here, our results demonstrate how ultrafast resonant inelastic X-ray scattering can help characterize local charge distributions around catalytic metal centers in short-lived charge-transfer excited states, as a step toward future rationalization and tailoring of photocatalytic capabilities of transition-metal complexes.« less

  4. Disentangling Transient Charge Density and Metal–Ligand Covalency in Photoexcited Ferricyanide with Femtosecond Resonant Inelastic Soft X-ray Scattering

    DOE PAGES

    Jay, Raphael M.; Norell, Jesper; Eckert, Sebastian; ...

    2018-06-11

    Soft X-ray spectroscopies are ideal probes of the local valence electronic structure of photocatalytically active metal sites. Here, we apply the selectivity of time-resolved resonant inelastic X-ray scattering at the iron L-edge to the transient charge distribution of an optically excited charge-transfer state in aqueous ferricyanide. Through comparison to steady-state spectra and quantum chemical calculations, the coupled effects of valence-shell closing and ligand-hole creation are experimentally and theoretically disentangled and described in terms of orbital occupancy, metal–ligand covalency, and ligand field splitting, thereby extending established steady-state concepts to the excited-state domain. π-Back-donation is found to be mainly determined by themore » metal site occupation, whereas the ligand hole instead influences σ-donation. Here, our results demonstrate how ultrafast resonant inelastic X-ray scattering can help characterize local charge distributions around catalytic metal centers in short-lived charge-transfer excited states, as a step toward future rationalization and tailoring of photocatalytic capabilities of transition-metal complexes.« less

  5. Polarization-Dependent Ti 2p-Resonant X-ray Raman Scattering from Ti2O3

    NASA Astrophysics Data System (ADS)

    Tezuka, Yasuhisa; Nakajima, Nobuo; Adachi, Jun-ichi; Morimoto, Osamu; Sato, Hitoshi; Uozumi, Takayuki

    2017-12-01

    Detailed resonant X-ray emission spectra (XES) and these polarization dependences of Ti2O3 were obtained by excitation at the Ti 2p absorption edge. About 100 XES spectra were observed in different polarization configurations. X-ray Raman scattering spectra showed two types of crystal field (dd) excitations as well as charge-transfer (CT) excitations. Bulk states of the powder sample were obtained by the XES measurement, which is the photon-in/photon-out method. Partial photon yields (PPYs) of some elementary excitations were extracted from the XES spectra. The CT excitations were hidden in total electron yield spectra, but these were revealed by PPY measurements. Symmetry information of these excitations was acquired on the basis of polarization dependences.

  6. Carbon Condensation during High Explosive Detonation with Time Resolved Small Angle X-ray Scattering

    NASA Astrophysics Data System (ADS)

    Hammons, Joshua; Bagge-Hansen, Michael; Nielsen, Michael; Lauderbach, Lisa; Hodgin, Ralph; Bastea, Sorin; Fried, Larry; May, Chadd; Sinclair, Nicholas; Jensen, Brian; Gustavsen, Rick; Dattelbaum, Dana; Watkins, Erik; Firestone, Millicent; Ilavsky, Jan; van Buuren, Tony; Willey, Trevor; Lawrence Livermore National Lab Collaboration; Los Alamos National Laboratory Collaboration; Washington State University/Advanced Photon Source Team

    Carbon condensation during high-energy detonations occurs under extreme conditions and on very short time scales. Understanding and manipulating soot formation, particularly detonation nanodiamond, has attracted the attention of military, academic and industrial research. An in-situ characterization of these nanoscale phases, during detonation, is highly sought after and presents a formidable challenge even with today's instruments. Using the high flux available with synchrotron X-rays, pink beam small angle X-ray scattering is able to observe the carbon phases during detonation. This experimental approach, though powerful, requires careful consideration and support from other techniques, such as post-mortem TEM, EELS and USAXS. We present a comparative survey of carbon condensation from different CHNO high explosives. This work was performed under the auspices of the US DOE by LLNL under Contract DE-AC52-07NA27344.

  7. X-Ray Thomson Scattering Without the Chihara Decomposition

    NASA Astrophysics Data System (ADS)

    Magyar, Rudolph; Baczewski, Andrew; Shulenburger, Luke; Hansen, Stephanie B.; Desjarlais, Michael P.; Sandia National Laboratories Collaboration

    X-Ray Thomson Scattering is an important experimental technique used in dynamic compression experiments to measure the properties of warm dense matter. The fundamental property probed in these experiments is the electronic dynamic structure factor that is typically modeled using an empirical three-term decomposition (Chihara, J. Phys. F, 1987). One of the crucial assumptions of this decomposition is that the system's electrons can be either classified as bound to ions or free. This decomposition may not be accurate for materials in the warm dense regime. We present unambiguous first principles calculations of the dynamic structure factor independent of the Chihara decomposition that can be used to benchmark these assumptions. Results are generated using a finite-temperature real-time time-dependent density functional theory applied for the first time in these conditions. Sandia National Laboratories is a multi-program laboratory managed and operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy's National Security Administration under contract DE-AC04-94AL85000.

  8. The x ray halo of AM Her

    NASA Technical Reports Server (NTRS)

    Catura, Richard C.

    1993-01-01

    The objective of this research was to study the halo surrounding the ROSAT image of the cataclysmic variable AM Her that is formed by scattering of x-rays by interstellar dust grains. AM Her was in a low state of x-ray emission during the 14,400 sec observation and thus an insufficient number of counts were obtained to detect the x-ray halo.

  9. An analysis of FtsZ assembly using small angle X-ray scattering and electron microscopy.

    PubMed

    Kuchibhatla, Anuradha; Abdul Rasheed, A S; Narayanan, Janaky; Bellare, Jayesh; Panda, Dulal

    2009-04-09

    Small angle X-ray scattering (SAXS) was used for the first time to study the self-assembly of the bacterial cell division protein, FtsZ, with three different additives: calcium chloride, monosodium glutamate and DEAE-dextran hydrochloride in solution. The SAXS data were analyzed assuming a model form factor and also by a model-independent analysis using the pair distance distribution function. Transmission electron microscopy (TEM) was used for direct observation of the FtsZ filaments. By sectioning and negative staining with glow discharged grids, very high bundling as well as low bundling polymers were observed under different assembly conditions. FtsZ polymers formed different structures in the presence of different additives and these additives were found to increase the bundling of FtsZ protofilaments by different mechanisms. The combined use of SAXS and TEM provided us a significant insight of the assembly of FtsZ and microstructures of the assembled FtsZ polymers.

  10. The Role of Inverse Compton Scattering in Solar Coronal Hard X-Ray and γ-Ray Sources

    NASA Astrophysics Data System (ADS)

    Chen, Bin; Bastian, T. S.

    2012-05-01

    Coronal hard X-ray (HXR) and continuum γ-ray sources associated with the impulsive phase of solar flares have been the subject of renewed interest in recent years. They have been interpreted in terms of thin-target, non-thermal bremsstrahlung emission. This interpretation has led to rather extreme physical requirements in some cases. For example, in one case, essentially all of the electrons in the source must be accelerated to non-thermal energies to account for the coronal HXR source. In other cases, the extremely hard photon spectra of the coronal continuum γ-ray emission suggest that the low-energy cutoff of the electron energy distribution lies in the MeV energy range. Here, we consider the role of inverse Compton scattering (ICS) as an alternate emission mechanism in both the ultra- and mildly relativistic regimes. It is known that relativistic electrons are produced during powerful flares; these are capable of upscattering soft photospheric photons to HXR and γ-ray energies. Previously overlooked is the fact that mildly relativistic electrons, generally produced in much greater numbers in flares of all sizes, can upscatter extreme-ultraviolet/soft X-ray photons to HXR energies. We also explore ICS on anisotropic electron distributions and show that the resulting emission can be significantly enhanced over an isotropic electron distribution for favorable viewing geometries. We briefly review results from bremsstrahlung emission and reconsider circumstances under which non-thermal bremsstrahlung or ICS would be favored. Finally, we consider a selection of coronal HXR and γ-ray events and find that in some cases the ICS is a viable alternative emission mechanism.

  11. X-ray shout echoing through space

    NASA Astrophysics Data System (ADS)

    2004-01-01

    a flash of X-rays hi-res Size hi-res: 3991 Kb Credits: ESA, S. Vaughan (University of Leicester) EPIC camera shows the expanding rings caused by a flash of X-rays XMM-Newton's X-ray EPIC camera shows the expanding rings caused by a flash of X-rays scattered by dust in our Galaxy. The X-rays were produced by a powerful gamma-ray burst that took place on 3 December 2003. The slowly fading afterglow of the gamma-ray burst is at the centre of the expanding rings. Other, unrelated, X-ray sources can also be seen. The time since the gamma-ray explosion is shown in each panel in hours. At their largest size, the rings would appear in the sky about five times smaller than the full moon. a flash of X-rays hi-res Size hi-res: 2153 Kb Credits: ESA, S. Vaughan (University of Leicester) EPIC camera shows the expanding rings caused by a flash of X-rays (Please choose "hi-res" version for animation) XMM-Newton's X-ray EPIC camera shows the expanding rings caused by a flash of X-rays scattered by dust in our Galaxy. The X-rays were produced by a powerful gamma-ray burst that took place on 3 December 2003. The slowly fading afterglow of the gamma-ray burst is at the centre of the expanding rings. Other, unrelated, X-ray sources can also be seen. The time since the gamma-ray explosion is shown in each panel in seconds. At their largest size, the rings would appear in the sky about five times smaller than the full moon. This echo forms when the powerful radiation of a gamma-ray burst, coming from far away, crosses a slab of dust in our Galaxy and is scattered by it, like the beam of a lighthouse in clouds. Using the expanding rings to precisely pin-point the location of this dust, astronomers can identify places where new stars and planets are likely to form. On 3 December 2003 ESA's observatory, Integral, detected a burst of gamma rays, lasting about 30 seconds, from the direction of a distant galaxy. Within minutes of the detection, thanks to a sophisticated alert network, many

  12. Functional materials analysis using in situ and in operando X-ray and neutron scattering

    PubMed Central

    Peterson, Vanessa K.; Papadakis, Christine M.

    2015-01-01

    In situ and in operando studies are commonplace and necessary in functional materials research. This review highlights recent developments in the analysis of functional materials using state-of-the-art in situ and in operando X-ray and neutron scattering and analysis. Examples are given covering a number of important materials areas, alongside a description of the types of information that can be obtained and the experimental setups used to acquire them. PMID:25866665

  13. Analysis and implementation of a space resolving spherical crystal spectrometer for x-ray Thomson scattering experiments.

    PubMed

    Harding, E C; Ao, T; Bailey, J E; Loisel, G; Sinars, D B; Geissel, M; Rochau, G A; Smith, I C

    2015-04-01

    The application of a space-resolving spectrometer to X-ray Thomson Scattering (XRTS) experiments has the potential to advance the study of warm dense matter. This has motivated the design of a spherical crystal spectrometer, which is a doubly focusing geometry with an overall high sensitivity and the capability of providing high-resolution, space-resolved spectra. A detailed analysis of the image fluence and crystal throughput in this geometry is carried out and analytical estimates of these quantities are presented. This analysis informed the design of a new spectrometer intended for future XRTS experiments on the Z-machine. The new spectrometer collects 6 keV x-rays with a spherically bent Ge (422) crystal and focuses the collected x-rays onto the Rowland circle. The spectrometer was built and then tested with a foam target. The resulting high-quality spectra prove that a spherical spectrometer is a viable diagnostic for XRTS experiments.

  14. Quantitative evaluation of statistical errors in small-angle X-ray scattering measurements

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sedlak, Steffen M.; Bruetzel, Linda K.; Lipfert, Jan

    A new model is proposed for the measurement errors incurred in typical small-angle X-ray scattering (SAXS) experiments, which takes into account the setup geometry and physics of the measurement process. The model accurately captures the experimentally determined errors from a large range of synchrotron and in-house anode-based measurements. Its most general formulation gives for the variance of the buffer-subtracted SAXS intensity σ 2(q) = [I(q) + const.]/(kq), whereI(q) is the scattering intensity as a function of the momentum transferq;kand const. are fitting parameters that are characteristic of the experimental setup. The model gives a concrete procedure for calculating realistic measurementmore » errors for simulated SAXS profiles. In addition, the results provide guidelines for optimizing SAXS measurements, which are in line with established procedures for SAXS experiments, and enable a quantitative evaluation of measurement errors.« less

  15. PLEIADES: a picosecond Compton scattering x-ray source for advanced backlighting and time-resolved material studies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gibson, D J; Anderson, S G; Barty, C P

    2003-10-20

    The PLEIADES (Picosecond Laser-Electron Inter-Action for the Dynamical Evaluation of Structures) facility has produced first light at 70 keV. This milestone offers a new opportunity to develop laser-driven, compact, tunable x-ray sources for critical applications such as diagnostics for the National Ignition Facility and time-resolved material studies. The electron beam was focused to 50 {micro}m rms, at 57 MeV, with 260 C of charge, a relative energy spread of 0.2%, and a normalized emittance of 5 mm mrad horizontally and 13 mm mrad vertically. The scattered 820-nm laser pulse had an energy of 180 mJ and a duration of 54more » fs. Initial x-rays were captured with a cooled charge-coupled device using a Cesium Iodide scintillator; the peak photon energy was approximately 78 keV, with a total x-ray flux of 1.3 x 10{sup 6} photons/shot, and the observed angular distribution found to agree very well with three-dimensional codes. Simple K-edge radiography of a tantalum foil showed good agreement with the theoretical divergence-angle dependence of the x-ray energy. Optimization of the x-ray dose is currently underway, with the goal of reaching 10{sup 8} photons per shot and a peak brightness approaching 10{sup 20} photons/mm{sup 2}/mrad{sup 2}/s/0.1%bandwidth.« less

  16. Critical behavior of the order-disorder phase transition in β -brass investigated by x-ray scattering

    NASA Astrophysics Data System (ADS)

    Madsen, A.; Als-Nielsen, J.; Hallmann, J.; Roth, T.; Lu, W.

    2016-07-01

    β -brass exhibits an archetypical example of an order-disorder transition with a critical behavior that was previously investigated by neutron scattering. The data were well described by the three-dimensional (3d) Ising model but the relatively crude experimental resolution prevented an in-depth examination of the single-length scaling hypothesis, a cornerstone in the theory of critical phenomena. With the development of synchrotron x-ray experiments, high-resolution data could be recorded and surprisingly it was found that the single-length scaling did not hold in most critical systems, possibly due to strain originating from surface defects and/or impurities. In this paper we demonstrate single-length critical behavior using high-resolution x-ray scattering in β -brass. The investigations confirm that β -brass behaves like a 3d Ising system over a wide range of length scales comprising correlated clusters of millions of atoms. To vary the surface sensitivity, experiments have been performed both in Bragg reflection and Laue transmission geometries but without any substantial differences observed in the scaling and critical behavior.

  17. Portable mini-chamber for temperature dependent studies using small angle and wide angle x-ray scattering

    NASA Astrophysics Data System (ADS)

    Dev, Arun Singh; Kumar, Dileep; Potdar, Satish; Pandit, Pallavi; Roth, Stephan V.; Gupta, Ajay

    2018-04-01

    The present work describes the design and performance of a vacuum compatible portable mini chamber for temperature dependent GISAXS and GIWAXS studies of thin films and multilayer structures. The water cooled body of the chamber allows sample annealing up to 900 K using ultra high vacuum compatible (UHV) pyrolytic boron nitride heater, thus making it possible to study the temperature dependent evolution of structure and morphology of two-dimensional nanostructured materials. Due to its light weight and small size, the chamber is portable and can be accommodated at synchrotron facilities worldwide. A systematic illustration of the versatility of the chamber has been demonstrated at beamline P03, PETRA-III, DESY, Hamburg, Germany. Temperature dependent grazing incidence small angle x-ray scattering (GISAXS) and grazing incidence wide angle x-ray scattering (GIWAXS) measurements were performed on oblique angle deposited Co/Ag multilayer structure, which jointly revealed that the surface diffusion in Co columns in Co/Ag multilayer enhances by increasing temperature from RT to ˜573 K. This results in a morphology change from columnar tilted structure to densely packed morphological isotropic multilayer.

  18. Diffuse X-ray scattering near a two-dimensional solid–liquid phase transition at the n-hexane–water interface

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tikhonov, A. M.

    According to experimental data on X-ray scattering and reflectometry with synchrotron radiation, a twodimensional crystallization phase transition in a monolayer of melissic acid at the n-hexane–water interface with a decrease in the temperature occurs after a wetting transition.

  19. Optical Design and Performance of the Taiwan Inelastic X-Ray Scattering Beamline (BL12XU) at SPring-8

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cai, Y.Q.; Chow, P.; Chen, C.C.

    2004-05-12

    As part of the Taiwan x-ray facility at SPring-8, we have designed, constructed and commissioned a dedicated Inelastic X-ray Scattering (IXS) beamline (BL12XU) for both resonant and non-resonant experiments on electronic excitations in correlated electron systems with energy resolution from 10-1000 meV. At the Si(555) near-backscattering energy of 9.886 keV, a total energy resolution of 70 meV has been achieved with flux of 1.5x1011 phs/sec/50meV. The optical design and performance of the beamline are presented and discussed with selected results from recent commissioning experiments.

  20. Innovative diffraction gratings for high-resolution resonant inelastic soft x-ray scattering spectroscopy

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Voronov, D.L.; Warwick, T.; Gullikson, E. M.

    2016-07-27

    High-resolution Resonant Inelastic X-ray Scattering (RIXS) requires diffraction gratings with very exacting characteristics. The gratings should provide both very high dispersion and high efficiency which are conflicting requirements and extremely challenging to satisfy in the soft x-ray region for a traditional grazing incidence geometry. To achieve high dispersion one should increase the groove density of a grating; this however results in a diffraction angle beyond the critical angle range and results in drastic efficiency loss. The problem can be solved by use of multilayer coated blazed gratings (MBG). In this work we have investigated the diffraction characteristics of MBGs viamore » numerical simulations and have developed a procedure for optimization of grating design for a multiplexed high resolution imaging spectrometer for RIXS spectroscopy to be built in sector 6 at the Advanced Light Source (ALS). We found that highest diffraction efficiency can be achieved for gratings optimized for 4{sup th} or 5{sup th} order operation. Fabrication of such gratings is an extremely challenging technological problem. We present a first experimental prototype of these gratings and report its performance. High order and high line density gratings have the potential to be a revolutionary new optical element that should have great impact in the area of soft x-ray RIXS.« less