A new time-of-flight small-angle scattering instrument at the Helmholtz-Zentrum Berlin: V16/VSANS

2014 ◽  
Vol 47 (1) ◽  
pp. 237-244 ◽  
Author(s):  
Karsten Vogtt ◽  
Miriam Siebenbürger ◽  
Daniel Clemens ◽  
Christian Rabe ◽  
Peter Lindner ◽  
...  
Keyword(s):  
Momentum Transfer ◽  
Small Angle ◽  
Soft Matter ◽  
Scattering Length ◽  
Time Of Flight ◽  
Small Angle Scattering ◽  
Neutron Guide ◽  
Macromolecular Assemblies ◽  
Angle Scattering ◽  
The Individual

Small-angle scattering methods have become routine techniques for the structural characterization of macromolecules and macromolecular assemblies like polymers, (block) copolymers or micelles in the spatial range from a few to hundreds of nanometres. Neutrons are valuable scattering probes, because they offer freedom with respect to scattering length density contrast and isotopic labelling of samples. In order to gain maximum benefit from the allotted experiment time, the instrumental setup must be optimized in terms of statistics of scattered intensity, resolution and accessible range in momentum transferQ. The new small-angle neutron scattering instrument V16/VSANS at the Helmholtz-Zentrum in Berlin, Germany, augments neutron guide collimation and pinhole optics with time-of-flight data recording and flexible chopper configuration. Thus, the availableQrange and the respective instrumental resolution in the intermediate and high momentum transfer regions can be adjusted and balanced to the individual experimental requirements. This renders V16/VSANS a flexible and versatile instrument for soft-matter research.

Contrast variation in small-angle scattering experiments on polydisperse and superparamagnetic systems: basic functions approach

2007 ◽  
Vol 40 (1) ◽  
pp. 56-70 ◽  
Author(s):  
Mikhail V. Avdeev
Keyword(s):  
Small Angle ◽  
Magnetic Particles ◽  
Scattering Length ◽  
Small Angle Scattering ◽  
Contrast Variation ◽  
Match Point ◽  
Scattering Intensity ◽  
Scattering Length Density ◽  
Angle Scattering ◽  
Basic Functions

The development of the basic functions approach [Stuhrmann (1995).Modern Aspects of Small-Angle Scattering, edited by H. Brumberger, pp. 221–254. Dordrecht: Kluwer Academic Publishers] for the contrast variation technique in small-angle scattering from systems of polydisperse and superparamagnetic non-interacting particles is presented. For polydisperse systems the modified contrast is introduced as the difference between the effective mean scattering length density (corresponding to the minimum of the scattering intensity as the function of the scattering length density of the solvent) and the density of the solvent. Then, the general expression for the scattering intensity is written in the classical way through the modified basic functions. It is shown that the shape scattering from the particle volume can be reliably obtained. Modifications of classical expressions describing changes in integral parameters of the scattering (intensity at zero angle, radius of gyration, Porod integral) with the contrast are analyzed. In comparison with the monodisperse case, the residual scattering in the minimum of intensity as a function of contrast (effective match point) in polydisperse systems makes it possible to treat the Guinier region of scattering curves around the effective match point quite precisely from the statistical viewpoint. However, limitations of such treatment exist, which are emphasized in the paper. In addition, the effect of magnetic scattering in small-angle neutron scattering from superparamagnetic nanoparticles is considered in the context of the basic functions approach. Conceptually, modifications of the integral parameters of the scattering in this case are similar to those obtained for polydisperse multicomponent particles. Various cases are considered, including monodisperse non-homogeneous and homogeneous magnetic particles, and polydisperse non-homogeneous and homogeneous magnetic particles. The developed approach is verified for two models representing the main types of magnetic fluids – systems of polydisperse superparamagnetic particles located in liquid carriers.

The time-of-flight small-angle scattering spectrometer SAN at the KENS pulsed cold neutron source

1986 ◽  
Vol 19 (4) ◽  
pp. 229-242 ◽  
Author(s):  
Y. Ishikawa ◽  
M. Furusaka ◽  
N. Niimura ◽  
M. Arai ◽  
K. Hasegawa
Keyword(s):  
Neutron Source ◽  
Small Angle ◽  
Cold Neutron ◽  
Time Of Flight ◽  
Small Angle Scattering ◽  
Angle Scattering ◽  
Cold Neutron Source

scholarly journals Small-Angle Scattering from Weakly Correlated Nanoscale Mass Fractal Aggregates

Nanomaterials ◽  
2019 ◽  
Vol 9 (4) ◽  
pp. 648 ◽  
Author(s):  
Eugen Mircea Anitas
Keyword(s):  
Structural Properties ◽  
Small Angle ◽  
Nanocomposite Materials ◽  
Small Angle Scattering ◽  
Detailed Knowledge ◽  
Fractal Aggregates ◽  
Angle Scattering ◽  
End Products ◽  
The Individual ◽  
Extract Information

Formation of fractal aggregates is generally an undesired effect which may lead to end products with worse properties as compared to those of the individual components, especially in nanocomposite materials. Although several methods exist to overcome this issue, such as inclusion of additives, irradiation grafting or sonication, their effectiveness relies on a detailed knowledge of the structural properties of the aggregates. Here, small-angle scattering (SAS) technique is used and a theoretical model based on a unified Guinier–Porod approach with weak correlations is developed for investigating the structural properties of nanoscale fractal aggregates. It is shown how one can extract information concerning the correlation length/degree between aggregates, their fractal dimension and the overall size. These parameters can be used for development of various types of novel nanomaterials with pre-determined properties and functions.

Structure and order in lamellar phases determined by small-angle scattering

2004 ◽  
Vol 37 (5) ◽  
pp. 703-710 ◽  
Author(s):  
Thomas Frühwirth ◽  
Gerhard Fritz ◽  
Norbert Freiberger ◽  
Otto Glatter
Keyword(s):  
Form Factor ◽  
Small Angle ◽  
Structure Factor ◽  
Scattering Length ◽  
Small Angle Scattering ◽  
Scattering Data ◽  
X Rays ◽  
Model Free ◽  
Angle Scattering

Multilamellar phases can be identified and characterized by small-angle scattering of X-rays (SAXS) or neutrons (SANS). Equidistant peaks are the typical signature and their spacing allows the fast determination of the repeat distance,i.e.the mean distance between the midplane of neighbouring bilayers. The scattering function can be described as the product of a structure factor and a form factor. The structure factor is related to the ordering of the bilayers and is responsible for the typical equidistant peaks, but it also contains information about the bilayer flexibility and the number of coherently scattering bilayers. The form factor depends on the thickness and the internal structure (scattering length density distribution) of a single bilayer. The recently developed generalized indirect Fourier transformation (GIFT) method is extended to such systems. This method allows the simultaneous determination of the structure factor and the form factor of the system, including the correction of instrumental broadening effects. A few-parameter model is used for the structure factor, while the determination of the form factor is completely model-free. The method has been tested successfully with simulated scattering data and by application to experimental data sets.

scholarly journals Small-angle scattering simulations for suspensions of nanocrystals

2014 ◽  
Vol 70 (a1) ◽  
pp. C597-C597
Author(s):  
Martin Schmiele ◽  
Simone Gehrer ◽  
Tobias Unruh
Keyword(s):  
Small Angle ◽  
Dispersion Medium ◽  
Scattering Length ◽  
Thickness Distribution ◽  
Reciprocal Lattice ◽  
Small Angle Scattering ◽  
Crystallographic Structure ◽  
Lattice Vector ◽  
Reliable Determination ◽  
Angle Scattering

Suspensions of nanocrystals which possess large lattice spacings d(hkl) and only a small number of unit cells along the direction of the reciprocal lattice vector G(hkl) can feature broadened Bragg peaks in small-angle scattering (SAS) patterns. The scattering from molecules located at the interface between the nanocrystals and the dispersion medium which stabilize and functionalize the nanocrystals can interfere with the scattering of the nanocrystals and affect the shape and position of their Bragg peaks. This allows to study how these molecules arrange on the surface of the nanocyrstals. As an example we study suspensions of lecithin stabilized β-tripalmitin nanocrystals which adopt a platelet-like shape. Their SAS patterns exhibit a broadened 001 Bragg peak (cf. SAXS curves in the graphical abstract). With the x-ray and neutron powder pattern simulation analysis (XNPPSA) we have demonstrated that the SAXS and SANS patterns of dilute tripalmitin (3 wt%) suspensions can be simultaneously reproduced on an absolute scale [1,2]. Thereby, powder averaged SAS diffractograms are computed for an ensemble of nanocrystals which are embedded in a dispersion medium. The crystallographic structure of the nanocrystals (CIF-file) and their geometry are taken into account and the amphiphilic lecithin molecules which cover the nanocrystals are modelled with two shells (cf. model in the right inset). From the analysis of the fitted shell thicknesses and scattering length densities it turns out that the lecithin molecules arrange rather flatly and densely packed on the surface of the nanocyrstals. Moreover, the XNPPSA method allows a reliable determination of the thickness distribution of the nanocrystals with molecular resolution [1,2]. With rising tripalmitin concentration the platelets form self-assembled stack-like structures [1,3] and finally nematic liquid-crystalline domains. The XNPPSA allows to investigate the structure and amount of such stacks in the suspensions.

Time-of-flight neutron small-angle scattering from a superconducting composite wire

1982 ◽  
Vol 15 (6) ◽  
pp. 611-614 ◽  
Author(s):  
K. Osamura ◽  
H. Tsunekawa ◽  
Y. Murakami ◽  
M. Ono ◽  
H. Yoshida ◽  
...  
Keyword(s):  
Small Angle ◽  
Time Of Flight ◽  
Small Angle Scattering ◽  
Composite Wire ◽  
Angle Scattering ◽  
Neutron Small Angle Scattering
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