Mesoscopic structure of SiC fibers by neutron and x-ray scattering

Mesoscopic structures of SiC fibers produced from polycarbosilane by different methods were studied by diffraction and small-angle scattering of neutrons and x-rays. Microvoids of a size of 4–10 Å in diameter have been observed for the first time by neutron scattering in a medium momentum transfer range (Q = 0.1–1.0 Å−1). The size and the volume fraction of β–SiC particles were determined for fibers prepared at different heat-treatment temperatures. The results show that wide-angle neutron scattering measurements are especially useful for the study of the mesoscopic structure of multicomponent materials.

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Isotope effects in solution small-angle X-ray scattering

Journal of Applied Crystallography ◽

10.1107/s0021889898010498 ◽

1999 ◽

Vol 32 (1) ◽

pp. 113-114 ◽

Cited By ~ 3

Author(s):

Stephen J. Henderson

Keyword(s):

Neutron Scattering ◽

Small Angle ◽

Small Angle Neutron Scattering ◽

Isotope Effects ◽

X Rays ◽

Light Water ◽

X Ray ◽

X Ray Scattering ◽

The Difference ◽

Ray Scattering

While the difference between using heavy and light water as solvents for small-angle neutron scattering experiments is well known, the lesser difference for the case of small-angle X-ray scattering with these same isotopes of water has, as yet, not been reported. This difference for the case of X-rays is discussed and quantified for several familiar materials: polystyrene latexes, proteins and lipids.

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Small-angle energy-dispersive X-ray scattering using a laboratory-based diffractometer with a conventional source

Journal of Applied Crystallography ◽

10.1107/s0021889806053295 ◽

2007 ◽

Vol 40 (2) ◽

pp. 218-231 ◽

Cited By ~ 4

Author(s):

Giuseppe Portale ◽

Alessandro Longo ◽

Lucio D'Ilario ◽

Andrea Martinelli ◽

Ruggero Caminiti ◽

...

Keyword(s):

Small Angle ◽

Energy Dispersive ◽

Protein Solutions ◽

X Rays ◽

Catalytic Systems ◽

X Ray ◽

X Ray Scattering ◽

Angle Scattering ◽

Ray Patterns ◽

Ray Scattering

The use of polychromaticBremsstrahlungX-rays generated by commercial tubes for energy-dispersive small-angle scattering measurements has not been extensively discussed in the literature, mainly because of some difficulties associated with it. If a suitable experimental setup is chosen and concomitant phenomena are taken into account for correcting the observed X-ray patterns, energy-dispersive small-angle X-ray scattering (SAXS) may become an interesting alternative to conventional measurements based on monochromatic beams. Energy-dispersive SAXS experiments carried out on protein solutions, micelles, semicrystalline polymers and catalytic systems are discussed to illustrate the new opportunities offered by this technique as well as its limitations.

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

Journal of Synchrotron Radiation ◽

10.1107/s1600577517018355 ◽

2018 ◽

Vol 25 (2) ◽

pp. 496-504 ◽

Cited By ~ 5

Author(s):

Sen Chen ◽

Sheng-Nian Luo

Keyword(s):

Small Angle ◽

Spectral Shape ◽

Spherical Particles ◽

X Rays ◽

X Ray ◽

X Ray Scattering ◽

High Harmonics ◽

Angle Scattering ◽

Particle Size Determination ◽

Photon Source

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, fundamental harmonic bandwidth and high harmonics. The effects of bandwidth, spectral shape and high harmonics on particle size determination are evaluated quantitatively.

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Interpretation of small-angle X-ray scattering patterns of crystalline triglyceride nanoparticles in dispersion

Journal of Applied Crystallography ◽

10.1107/s0021889807044378 ◽

2007 ◽

Vol 40 (6) ◽

pp. 1008-1018 ◽

Cited By ~ 13

Author(s):

T. Unruh

Keyword(s):

Small Angle ◽

Simulation Analysis ◽

Aqueous Dispersion ◽

Small Angle Scattering ◽

X Rays ◽

X Ray ◽

Scattering Model ◽

X Ray Scattering ◽

Angle Scattering ◽

Ray Scattering

Triglyceride nanocrystals in aqueous dispersion produced by high-pressure melt homogenization exhibit platelet-like shapes and clear but broadened Bragg reflections in the small-angle scattering regime. Because the particle thickness, the thickness of the stabilizer layer, the length scale of the crystalline structure of the nanoparticles and often the interparticle distances are of the same order of magnitude, the scattering of these structures mutually interferes. This leads to complicated small-angle scattering patterns which exhibit a lot of features, but it is not straightforward to discover the contained information on the structure of the system. In this contribution, a scattering model for such systems will be described, which is based on the kinematic scattering theory of X-rays. Using this scattering model an X-ray powder pattern simulation analysis is introduced to gain information on tripalmitin nanosuspensions which have been investigated by synchrotron small-angle X-ray scattering. It will be demonstrated that the results of this method provide a consistent description of all structural details mentioned above. In particular, information on the extension and the molecular packing density of the stabilizer layers can be achieved because these layers exhibit a comparatively large scattering contrast.

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Small-Angle X-ray Scattering at the ESRF High-Brilliance Beamline

Journal of Applied Crystallography ◽

10.1107/s0021889897001647 ◽

1997 ◽

Vol 30 (5) ◽

pp. 867-871 ◽

Cited By ~ 22

Author(s):

P. Bösecke ◽

O. Diat

Keyword(s):

Small Angle ◽

Small Angle Scattering ◽

Optical Systems ◽

Photon Flux ◽

X Rays ◽

Time Resolved ◽

X Ray ◽

X Ray Scattering ◽

Angle Scattering ◽

Ray Scattering

The high-brilliance beamline (BL4/ID2) at the European Synchrotron Radiation Facility (ESRF) in Grenoble has been constructed with the emphasis on time-resolved small-angle X-ray scattering and macromolecular crystallography. It has been open to users for two years. The beamline has opened up new areas in small-angle scattering research, facilitating (a) small-angle crystallography on structures with unit cells of several hundredths of nanometres, (b) overlap with the light scattering range for the study of optical systems, (c) high photon flux for time-resolved experiments and (d) a high spatial coherence allowing submicrometre imaging with X-rays. The set-up and the detector system of the small-angle scattering station are presented. A method for obtaining absolute scattering intensities is described. The parasitic background at the station is discussed in terms of absolute scattering intensities.

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A new method for evaluating the size of plate-like precipitates by small-angle scattering

Journal of Applied Crystallography ◽

10.1107/s0021889812039891 ◽

2012 ◽

Vol 45 (6) ◽

pp. 1208-1218 ◽

Cited By ~ 35

Author(s):

Frédéric De Geuser ◽

Françoise Bley ◽

Alexis Deschamps

Keyword(s):

Small Angle ◽

Volume Fraction ◽

Small Angle Scattering ◽

Number Density ◽

X Ray ◽

X Ray Scattering ◽

Angle Scattering ◽

Ewald Sphere ◽

Scattering Study

A methodology is presented for extracting the thickness and length of plate-like precipitates from streaking that appears in the small-angle scattering pattern of moderately textured polycrystalline samples. This methodology builds upon existing work on single crystals but is extended to polycrystals through a modeling of the streaking misalignment distribution. It is also shown that it is essential to take into account the Ewald sphere curvature. The protocol is applied to anin situsmall-angle X-ray scattering study of the transition between θ′ andT1in an Al–Li–Cu system, where the contributions of both phases are well separated, and the size, volume fraction and number density are monitored.

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SCT: a suite of programs for comparing atomistic models with small-angle scattering data

Journal of Applied Crystallography ◽

10.1107/s1600576715007062 ◽

2015 ◽

Vol 48 (3) ◽

pp. 953-961 ◽

Cited By ~ 20

Author(s):

David W. Wright ◽

Stephen J. Perkins

Keyword(s):

Small Angle ◽

Data Bank ◽

Scattering Data ◽

X Ray ◽

X Ray Scattering ◽

Angle Scattering ◽

Atomistic Models ◽

First Time ◽

Best Fit ◽

Theoretical Scattering

Small-angle X-ray and neutron scattering techniques characterize proteins in solution and complement high-resolution structural studies. They are of particular utility when large proteins cannot be crystallized or when the structure is altered by solution conditions. Atomistic models of the averaged structure can be generated through constrained modelling, a technique in which known domain or subunit structures are combined with linker models to produce candidate global conformations. By randomizing the configuration adopted by the different elements of the model, thousands of candidate structures are produced. Next, theoretical scattering curves are generated for each model for trial-and-error fits to the experimental data. From these, a small family of best-fit models is identified. In order to facilitate both the computation of theoretical scattering curves from atomistic models and their comparison with experiment, theSCTsuite of tools was developed.SCTalso includes programs that provide sequence-based estimates of protein volume (either incorporating hydration or not) and add a hydration layer to models for X-ray scattering modelling. The originalSCTsoftware, written in Fortran, resulted in the first atomistic scattering structures to be deposited in the Protein Data Bank, and 77 structures for antibodies, complement proteins and anionic oligosaccharides were determined between 1998 and 2014. For the first time, this software is publicly available, alongside an easier-to-use reimplementation of the same algorithms in Python. Both versions ofSCThave been released as open-source software under the Apache 2 license and are available for download from https://github.com/dww100/sct.

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A combined characterization of clusters in naturally aged Al–Cu–(Li, Mg) alloys using small-angle neutron and X-ray scattering and atom probe tomography

Journal of Applied Crystallography ◽

10.1107/s1600576717014443 ◽

2017 ◽

Vol 50 (6) ◽

pp. 1725-1734 ◽

Cited By ~ 8

Author(s):

R. Ivanov ◽

A. Deschamps ◽

F. De Geuser

Keyword(s):

Small Angle ◽

Atom Probe Tomography ◽

Atom Probe ◽

X Rays ◽

Contrast Variation ◽

X Ray ◽

X Ray Scattering ◽

Angle Scattering ◽

Aged State

A new methodology for the characterization of solute clusters leading to compositional fluctuations is presented and discussed. The methodology makes use of contrast variation arising from a combination of small-angle scattering using neutrons and X-rays, and adapts a model for solute correlation to extract the chemistry and length scale of clustered states after quench and after natural ageing. In three subsets of the Al–Cu system, Cu-rich clusters are reported for all cases. The presence of Mg strongly enhances Cu clustering in the naturally aged state and results in more than double the number of clusters in the complex Al–Cu–Li–Mg system. The results are compared with those obtained using atom probe tomography.

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Observations of X-rays from Laboratory Sparks in Air at Atmospheric Pressure under Negative Switching Impulse Voltages

Atmosphere ◽

10.3390/atmos10040169 ◽

2019 ◽

Vol 10 (4) ◽

pp. 169 ◽

Cited By ~ 1

Author(s):

Mahbubur Rahman ◽

Pasan Hettiarachchi ◽

Vernon Cooray ◽

Joseph Dwyer ◽

Vladimir Rakov ◽

...

Keyword(s):

Rise Time ◽

Atmospheric Pressure ◽

Opposite Polarity ◽

X Rays ◽

X Ray ◽

Impulse Voltage ◽

First Time ◽

Switching Impulses ◽

Low Rate

We present observations of X-rays from laboratory sparks created in the air at atmospheric pressure by applying an impulse voltage with long (250 µs) rise-time. X-ray production in 35 and 46 cm gaps for three different electrode configurations was studied. The results demonstrate, for the first time, the production of X-rays in gaps subjected to switching impulses. The low rate of rise of the voltage in switching impulses does not significantly reduce the production of X-rays. Additionally, the timing of the X-ray occurrence suggests the possibility that the mechanism of X-ray production by sparks is related to the collision of streamers of opposite polarity.

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