Butterfly Patterns: an Anomaly Common to the Neutron Scattering Spectra of Elongated Rubbers, Melts and Gels:

1991 ◽  
Vol 248 ◽  
Author(s):  
J. Bastide ◽  
F. Boue ◽  
R. Oeser ◽  
E. Mendes ◽  
F. Zielinski ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Proportion ◽  
Small Angle Neutron Scattering ◽  
Scattered Intensity ◽  
Extension Ratio ◽  
Scattering Spectra ◽  
First Time ◽  
Direction Opposite ◽  
Q Values

AbstractA totally unexpected phenomenon has been observed for the first time a few years ago when studying, by small angle neutron scattering, rubbery networks containing a small proportion of uncrosslinked labelled (deuterated) chains [1].When such a system is elongated, the scattered intensity strongly increases with the extension ratio λ for q vectors parallel to the stretching direction (and for low q values). Conversely, in the direction perpendicular to the elongation axis, the scattered intensity slightly decreases at low q for small extension ratios and then remains approximately constant when λ is further increased. The changes which are observed occur therefore in a direction opposite to the “conventional” one, i.e. that corresponding to chains effectively linked by at least two chemical junctions to the network and thus oriented on an average along the direction of stretching.

scholarly journals H2O/D2O Contrast Variation for Ultra-Small-Angle Neutron Scattering to Minimize Multiple Scattering Effects of Colloidal Particle Suspensions

2018 ◽  
Vol 2 (3) ◽  
pp. 37 ◽  
Author(s):  
Akira Otsuki ◽  
Liliana de Campo ◽  
Christopher Garvey ◽  
Christine Rehm
Keyword(s):  
Neutron Scattering ◽  
Multiple Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Colloidal Particle ◽  
Scattered Intensity ◽  
Particle Suspensions ◽  
Scattering Effects ◽  
Multiple Scattering Effects ◽  
Q Values

This study investigated the use of solvent contrast (H2O/D2O ratio) as a means to optimize the ultra-small-angle neutron scattering (USANS) signal. By optimizing the signal, it was possible to reduce the undesirable effects of coherent multiple scattering while still maintaining a measurable scattered intensity. This result will further enable the use of USANS as a probe of the interactions between colloidal particles and their structures within concentrated suspensions as well as particle dispersion/aggregation. As a model system, we prepared silica colloidal particle suspensions at different solid concentrations. USANS curves were measured using the classical Bonse–Hart double crystal diffractometer while varying the scattering length density of the aqueous phase, thus varying the contrast to the silica particles. As a means of assessing the impact of multiple scattering effects on different q-values, we analyzed the scattered intensity at different contrasts at three different q values. The data were then used to determine the match point of the silica particle suspensions from the expected square root dependence of the scattered intensity with solvent composition, to analyze any differences associated with the solid concentration change, and to determine the optimum H2O/D2O ratio in terms of high transmission (TSAS > 80%) and high enough scattering intensity associated with the contrast of the system. Through this investigation series, we confirmed that adjusting the contrast of the solvent (H2O/D2O) is a good methodology to reduce multiple scattering while maintaining a strong enough scattering signal from a concentrated suspension of silica particles for both USANS and rheometric USANS (rheo-USANS) experiments.

Modeling and small-angle neutron scattering spectra of chromatin supernucleosomal structures at genome scale

2011 ◽  
Vol 110 (10) ◽  
pp. 102217 ◽  
Author(s):  
Andrey V. Ilatovskiy ◽  
Dmitry V. Lebedev ◽  
Michael V. Filatov ◽  
Mikhail Grigoriev ◽  
Michael G. Petukhov ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Scattering Spectra ◽  
Genome Scale

Study on Calibrating Neutron Velocity Selector of Small Angle Neutron Scattering Instrument

2013 ◽  
Vol 433-435 ◽  
pp. 837-843
Author(s):  
Zhou Xiang Yu ◽  
Yun Tao Liu ◽  
He Cheng ◽  
Li Zhang ◽  
Dong Feng Chen
Keyword(s):  
Measurement Error ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Dead Time ◽  
Resolution Rate ◽  
Upper Limits ◽  
Wavelength Resolution ◽  
Total Measurement Time ◽  
First Time

Neutron velocity selector is widely used on neutron scattering instruments as key component. To calibrate it (wavelength and wavelength-resolution-rate measurement), it is necessary to design calibration instrument and develop calibration technique. Based on small angle neutron scattering instrument (SANS) at China Advanced Research Reactor (CARR), instrument structure was designed and instrument parameters were determined. Count loss influence on measurement of wavelength resolution rate (WRR) was studied for the first time. Measurement error of WRR is decided by product of dead time and Gauss peak count rate (GPCR) and increases with increasing GPCR for the same dead time. In order to ensure WRR measurement error less than 0.9%, upper limits of GPCR for detector adjoining chopper and detector far away from chopper are less than 10000[s-1] and 2500[s-1] respectively. According to upper limits of GPCR, floor limit of total measurement time for each spectrum is calculated to be 6.66 minutes.

On the design and experimental realization of a multislit-based very small angle neutron scattering instrument at the European Spallation Source

2015 ◽  
Vol 48 (4) ◽  
pp. 1242-1253 ◽  
Author(s):  
Sohrab Abbas ◽  
Sylvain Désert ◽  
Annie Brûlet ◽  
Vincent Thevenot ◽  
Patrice Permingeat ◽  
...  
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Feasibility Studies ◽  
Experimental Realization ◽  
Order Of Magnitude ◽  
Spallation Source ◽  
Length Scaling ◽  
First Time ◽  
Sans Instrument

This article reports the design of a versatile multislit-based very small angle neutron scattering (VSANS) instrument working either as a dedicated instrument or as an add-on for any small-angle neutron scattering machine like the proposed SANS instrument, SKADI, at the future European Spallation Source. The use of multiple slits as a VSANS collimator for the time-of-flight techniques has been validated usingMcStassimulations. Various instrument configurations to achieve different minimum wavevector transfers in scattering experiments are proposed. The flexibility of the multislit VSANS instrument concept is demonstrated by showing the possibility of instrument length scaling for the first time, allowing access to varying minimum wavevector transfers with the same multislit setup. These options can provide smooth access to minimum wavevector transfers lower than ∼4 × 10−5 Å−1and an overlapping of wavevector coverage with normal SANS mode,e.g.with the SKADI wavevector range of 10−3–1.1 Å−1. Such an angularly well defined and intense neutron beam will allow faster SANS studies of objects larger than 1 µm. Calculations have also been carried out for a radial collimator as an alternative to the multislit collimator setup. This extends the SANSQrange by an order of magnitude to 1 × 10−4 Å−1with much simpler alignment. The multislit idea has been realized experimentally by building a prototype at Laboratoire Leon Brillouin, Saclay, with cross-talk-free geometry. Feasibility studies were carried out by making VSANS measurements with single- and multislit collimators, and the results are compared with multiple-pinhole geometry using classical SANS analysis tools.

scholarly journals The impact of radical loading and oxidation on the conformation of organic radical polymers by small angle neutron scattering

2018 ◽  
Vol 6 (32) ◽  
pp. 15659-15667 ◽  
Author(s):  
Halie J. Martin ◽  
Barbara K. Hughes ◽  
Wade A. Braunecker ◽  
Thomas Gennett ◽  
Mark D. Dadmun
Keyword(s):  
Molecular Structure ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Organic Radical ◽  
The Impact ◽  
First Time ◽  
Insight Into

SANS provides, for the first time, unique insight into the correlation between organic radical polymer molecular structure and their assembly.

Light-induced structural evolution of photoswitchable carbohydrate-based surfactant micelles

2015 ◽  
Vol 51 (25) ◽  
pp. 5509-5512 ◽  
Author(s):  
Rico F. Tabor ◽  
Matthew J. Pottage ◽  
Christopher J. Garvey ◽  
Brendan L. Wilkinson
Keyword(s):  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Structural Changes ◽  
Structural Evolution ◽  
Time Resolved ◽  
Surfactant Micelles ◽  
First Time ◽  
Over Time

We report the light-induced structural evolution of photoswitchable carbohydrate-based surfactant micelles using time-resolved small-angle neutron scattering (TR-SANS), monitoring the structural changes in micellisation in situ over time and demonstrating for the first time the course and implications of this process.

scholarly journals Small-angle neutron scattering solution structures of NADPH-dependent sulfite reductase

2020 ◽  
Author(s):  
Daniel T Murray ◽  
Kevin Weiss ◽  
Christopher B Stanley ◽  
Gergely Nagy ◽  
M. Elizabeth Stroupe
Keyword(s):  
Electron Transfer ◽  
Neutron Scattering ◽  
Small Angle ◽  
Small Angle Neutron Scattering ◽  
Single Copy ◽  
Sulfite Reductase ◽  
Solution Structures ◽  
Contrast Matching ◽  
First Time ◽  
Binding Position

Sulfite reductase (SiR), a dodecameric complex of flavoprotein reductase subunits (SiRFP) and hemoprotein oxidase subunits (SiRHP), reduces sulfur reduction for biomass incorporation. Electron transfer within SiR requires intra- and inter-subunit interactions that are mediated by the relative position of each protein, governed by flexible domain movements. Using small-angle neutron scattering, we report the first solution structures of SiR heterodimers containing a single copy of each subunit. These structures show how the subunits bind and how both subunit binding and oxidation state impact SiRFP's conformation. Neutron contrast matching experiments on selectively deuterated heterodimers allow us to define the contribution of each subunit to the solution scattering. SiRHP binding induces a change in the position of SiRFP's flavodoxin-like domain relative to its ferredoxin-NADP+ reductase domain while compacting SiRHP's N-terminus. Reduction of SiRFP leads to a more open structure relative to its oxidized state, re-positioning SiRFP's N-terminal flavodoxin-like domain towards the SiRHP binding position. These structures show, for the first time, how both SiRHP binding to, and reduction of, SiRFP positions SiRFP for electron transfer between the subunits.

Fractal Pores or a Distribution of Pore sizes: Alternative Interpretations of Power-Law Small-Angle Scattering

1986 ◽  
Vol 73 ◽  
Author(s):  
Paul W. Schmidt
Keyword(s):  
Fractal Dimension ◽  
Neutron Scattering ◽  
Power Law ◽  
Small Angle ◽  
Scattered Intensity ◽  
X Ray ◽  
Number Distribution ◽  
Angle Scattering ◽  
Q Values ◽  
Boundary Surfaces

ABSTRACTThe intensity I(q) of the small-angle x-ray or neutron scattering has been calculated for a system of randomly oriented, independently scatter-ing pores with a number distribution of pore diameters which has the form of a power law. As has already been shown, [P. W. Schmidt, J. Appl. Cryst. 15, 567–569 (1982)], when the number distribution of the maximum diameters a of the pores is proportional to a−γ, I(q) is proportional to q−(7−γ), where q = 4πλ−1sin(θ/2), θ is the scattering angle, and λ is the wavelength. The coefficient of the power-law intensity has been expressed in terms of some of the constants which determine the diameter distribu-tion. Equations have been obtained for the scattered intensity I(q) at q values larger and smaller than those at which power-law scattering occurs. The intensity scattered by this system is compared with the intensity from a system of pores with fractal pore-boundary surfaces which have a fractal dimension D.

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