Diffusion des Rayons X aux petits angles / Small Angle X-Rays Scattering (SAXS)

X-rays are used to investigate the structural properties of solids, liquids or gels. Photons interact with electrons, and provide information about the fluctuations of electronic densities in heterogeneous matter. A typical experimental set-up is shown on Figure : a monochromatic beam of incident wave vector is selected and falls on the sample. The scattered intensity is collected as a function of the so-called scattering angle 2 teta.
The scattered intensity I(q) is the Fourier Transform of the correlation function of the electronic density.

Small angle scattering experiments are designed to measure I(q) at very small scattering vectors in order to investigate systems with characteristic sizes ranging from crystallographic distances (few Å) to colloidal sizes (up to few microns).


What is measured in a Small Angle X-ray Scattering (SAXS) ?

description of different experiment at  LIONS / LLB:

#737 - Màj : 06/06/2017
Technique (desc. gen.)
3D view of the design We have designed and regularly upgrade an in-house SAXS experiment for high sensitivity measurements. The generator is a copper rotating anode Rigaku RUH3R, with a fine focus filament. The optic is composed by an Xenocs collimating multilayer mirror, coupled with home made hybrid cristal slits. The source - sample distance is around 200 cm. We take attention to reduce the air quantities between the sample and the vacuum chamber.
La structure sur des échelles de 1 à 100 nm
Le LLB dispose de 4 appareils de diffusions de neutrons aux petits angles (PA), de gauche à droite : PACE   PA20 Small Angle Neutron Spectrometer PAxy Petits angles, détecteur 2d XY TPA   Très petits angles   Différentes architectures moléculaires étudiées par diffusion de neutrons aux petits angles.
A. Thill, O.Spalla, S.Lyonnard, J. Lambard
A Bonse/Hart camera has been built [*] in order to measure ultra small angle X-ray scattering (What is measured in a Small Angle X-ray Scattering (SAXS) ?). A mirror installed between the source and the first slits increases the incident flux on the monochromator : a factor of ten has been gained. Fifty millions of photons per second actually arrive on the sample.
MOMAC (Molybdenum for Condensed Matter)
MOMAC (Molybdenum for Condensed Matter) Momac is a Wide Angle X-Ray Scattering experiment, issue of a collaboration between CEA-LIONS and LPS-Orsay. The experiment is based on LPS-Orsay. LPS team is in charge of the X-ray generator, and LIONS team is in charge of the WAXS experiment. Funding was provided by the Triangle de la Physique in 2010. The experiment is open for the academic SAXS users of the RTRA, or industrial partnership. Beam time can be asked to Olivier TACHE (LIONS).
O. Taché*, O. Spalla*, P. Launois†, M. Pelloux†, Ph. Joly†, S. Rouziere† (* CEA - LIONS, † LPS Orsay)
La diffusion et diffraction des rayons X jouent un rôle important dans le développement des nano briques utilisées dans les nouveaux systèmes électroniques, et l'analyse quantitative de nombreux nanomatériaux. La possibilité de caractériser des échantillons sans préparation préalable contraignante est une qualité essentielle de ces techniques.
The Laboratoire Léon Brillouin (LLB) has installed in the "SWAXSLab" within the CEA Saclay a high resolution X-ray spectrometer Xeuss 2.0 from Xenoxs company ). This equipment aims at SAXS/ GISAXS and X-ray Reflectometry measurements as complements to SANS/ GISANS and Neutron Reflectometry experiments.
X-rays are used to investigate the structural properties of solids, liquids or gels. Photons interact with electrons, and provide information about the fluctuations of electronic densities in the matter. A typical experimental set-up is shown on Figure 1 : a monochromatic beam of incident wave vector ki is selected and falls on the sample. The scattered intensity is collected as a function of the so-called scattering angle 2θ.
Voir aussi
Research The group's current fields of interest are the following: Nanomaterials: In our laboratory, we synthesize and characterize low dimensionality materials (0, 1 and 2D), by all means necessary and available. These materials can often be exfoliated/dispersed in solution leading to some complex/colloidal fluids, exhibiting a very wide range of fascinating behaviors.
Jun Han (PhD), Sergio Gomez (PhD, University of Vigo), Zeliha Cansu Canbek (running PhD), Fabien Hubert (PhD 2009), Benjamin Abécassis (PhD 2006), Fabienne Testard, Olivier Spalla
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