Improving sensitivity of a small angle x-ray scattering camera with pinhole collimation using separated optical elements

International audienceWe show that a significant improvement in the sensitivity of a Huxley–Holmes design for a small angle x-ray scattering camera is obtained by separating the mirror and the monochromator. The design of the camera involves a long x-ray mirror close to a point x-ray source associated with a curved focusing crystal located close to the sample. The sample area is located at half the distance between the source and detector planes. Diffuse scattering produced by the mirror is not incident on the focusing crystal, thus reducing the background signal. Complete elimination of hard x rays allows precise calibration and hence absolute determination of sample cross section by means of a semitransparent beam stop. In pinhole geometry, the flux corresponds to a ;107 photons/s through the sample, collimated to 1022 Å21 in q range. This allows determination of scattered intensities on the order of 1023 cm21, corresponding to the scattering related to isothermal compressibility of less than 0.1 mm of pure water. As a reference sample, the widely used Lupolen™, a semicrystalline polymer, is calibrated. The high-q limit (q'4.5 nm21) of a porous calcite sample can be used as a secondary standard for specific area determination of solid/solid or solid–liquid dispersions

MOMAC: a SAXS/WAXS laboratory instrument dedicated to nanomaterials

International audienceThis article presents the technical characteristics of a newly built small-and wide-angle X-ray scattering (SAXS/WAXS) apparatus dedicated to structural characterization of a wide range of nanomaterials in the powder or dispersion form. The instrument is based on a high-flux rotating anode generator with a molybdenum target, enabling the assessment of highly absorbing samples containing heavy elements. The SAXS part is composed of a collimation system including a multilayer optic and scatterless slits, a motorized sample holder, a vacuum chamber, and a two-dimensional image-plate detector. All the control command is done through a TANGO interface. Normalization and data correction yield scattering patterns at the absolute scale automatically with a q range from 0.03 to 3.2 A ˚ À1. The WAXS part features a multilayer collimating optic and a two-dimensional image-plate detector with variable sample-to-detector distances. The accessible q range is 0.4–9 A ˚ À1 , ensuring a large overlap in q range between the two instruments. A few examples of applications are also presented, namely coupled SAXS/WAXS structure and symmetry determination of gold nanocrystals in solution and characterization of imogolite nanotubes and iron-filled carbon nanotube samples

Apport du projet INANOPART pour la mesure de taille et concentration de nanoparticules

International audienceLa mesure de la concentration de particules en suspension est un intérêt commercial majeur pour assurer la conformité avec la réglementation actuelle et future de l'DE, liée à la défInition de l'UE d'un nanomatériau pour garantir la fIabilité, la performance et la durée de vie dans la formulation de produits manufacturés contenant des nanoparticules. Actuellement, un certain nombre de méthodes perinettent cette mesure, mais il n'existe aucune norme ou méthodes de base. L'influence de la stabilité de l'échantillon, l'incertitude et la comparabilité des méthodes n'a pas été établie, même pour les matériaux idéaux, et aucun matériel de référence valide n' existe pour l'étalonnage des instruments couramment utilisés. Le projet EMPIR Innanopart en cours d' achèvement va permettre d'établir des documents de référence nécessaires, afm d'évaluer et de comparer les performances des différentes techniques, et d'entreprendre des études de pré-normalisation et des normes intemationalement reconnues. Au sein de ce projet, le travail du CEA a consisté en la synthèse de nanoparticules particulièrement monodisperses et stables dans le temps et en leur caractérisation (taille, distribution en taille, concentration) par SAXS et ICPMS. Ces travaux nous ont permis de développer des protocoles pour augmenter la fIabilité des mesures et de réaliser des comparaisons entre echniques instrumentales SAXS et spICPMS

Small Angle X-Rays Scattering for nanoparticles metrology and synthesis

International audienc

Apport du projet INANOPART pour la mesure de taille et concentration de nanoparticules

International audienceLa mesure de la concentration de particules en suspension est un intérêt commercial majeur pour assurer la conformité avec la réglementation actuelle et future de l'DE, liée à la défInition de l'UE d'un nanomatériau pour garantir la fIabilité, la performance et la durée de vie dans la formulation de produits manufacturés contenant des nanoparticules. Actuellement, un certain nombre de méthodes perinettent cette mesure, mais il n'existe aucune norme ou méthodes de base. L'influence de la stabilité de l'échantillon, l'incertitude et la comparabilité des méthodes n'a pas été établie, même pour les matériaux idéaux, et aucun matériel de référence valide n' existe pour l'étalonnage des instruments couramment utilisés. Le projet EMPIR Innanopart en cours d' achèvement va permettre d'établir des documents de référence nécessaires, afm d'évaluer et de comparer les performances des différentes techniques, et d'entreprendre des études de pré-normalisation et des normes intemationalement reconnues. Au sein de ce projet, le travail du CEA a consisté en la synthèse de nanoparticules particulièrement monodisperses et stables dans le temps et en leur caractérisation (taille, distribution en taille, concentration) par SAXS et ICPMS. Ces travaux nous ont permis de développer des protocoles pour augmenter la fIabilité des mesures et de réaliser des comparaisons entre echniques instrumentales SAXS et spICPMS

Role of the environment in the stability of anisotropic gold particles

International audienceDespite the long-lasting interest in the synthesis control of nanoparticles (NPs) in both fundamental and applied nanosciences, the driving mechanisms responsible for their size and shape selectivity in an environment (solution) are not completely understood, and a clear assessment of the respective roles of equilibrium thermodynamics and growth kinetics is still missing. In this study, relying on an efficient atomistic computational approach, we decipher the dependence of energetics, shapes and morphologies of gold NPs on the strength and nature of the metal–environment interaction. We highlight the conditions under which the energy difference between isotropic and elongated gold NPs is reduced, thus prompting their thermodynamic coexistence. The study encompasses both monocrystalline and multi-twinned particles and extends over size ranges particularly representative of the nucleation and early growth stages. Computational results are further rationalized with arguments involving the dependence of facet and edge energies on the metal–environment interactions. We argue that by determining the abundance and diversity of particles nucleated in solution, thermodynamics may constitute an important bias influencing their final shape. The present results provide firm grounds for kinetic simulations of particle growth

Accurate protocol for nanoparticles analysis (size, size distribution, concentration) by SAXS and spICPMS

International audienceSmall Angles X-Ray Scattering (SAXS) has been established as a metrological method for the determination of nanoparticles size and size distribution. Modern SAXS Laboratory experiments, by involving synchrotron-based instrumentation at lower price and very stable X-ray source, are more and more use in nanomaterials domain. In the frame of the Innanopart project we have develop a methodology for the size and concentration determination of spheric Silica nanoparticles. This protocol involves a precise sample preparation, and a set of homemade software tools for the data processing-from the acquisition, the absolute scaling, to the analysis. spICPMs is not a metrological traceable technique but has many strengths to become a useful complement of nanoparticle characterization methods such as SAXS and microscopy. It can also measure highly diluted nanoparticles suspensions which is not the case of Dynamic Light scattering (DLS) or SAXS. Finally, ICPMS analyzes inorganic ions in liquid solution in a very large range of concentration, which should allow linear diameter measurement range over at least 3 orders of magnitude by spICPMS. In this work, we confront spICPMS, as a counting technique, with SAXS in order to investigate the method and the developed protocols on a set of commercial Gold Nanoparticles

5.3. Hygiène dans la cuisine domestique

En France, une épidémie de maladies infectieuses d’origine alimentaire sur trois survient dans le cadre familial, souvent par méconnaissance des règles d’hygiène. Comment se diffusent les microorganismes infectieux ? Les principales voies d’entrée des microorganismes sont les aliments et les personnes elles-mêmes : nous hébergeons tous sur la peau, dans la gorge, le nez ou les intestins des microorganismes, parfois pathogènes (par exemple les bactéries appartenant aux genres E..

A SAXS/WAXS laboratory instrument for nanomaterials characterization

International audienceSmall Angle X-ray Scattering (SAXS) allows traceable measurements of size, size distribution , surface area, concentration and shape of nanomaterials in solutions, powders and in bulk materials. We present here a custom-made state-of-the-art SAXS laboratory instrument (see Figure 1) based on Mo X-ray generator. Its design has been thought and optimized for the wide angles (WAXS) for investigate nanostructured material in particular in the size range from below 1 nm to above 20 nm. The X-ray generator is a molybdenum (17 keV) rotating anode. A combination of a multilayer collimating mirror and a patented hybrid slits gives us a very sharp and high purity beam for a laboratory setup, with a size of 1x1 mm2 and a flux of 10 8 photons/s. The motorized sample holder can load 20 capil-laries, a temperature controlled system or a circulation environment system for kinetic studies. A vacuum chamber is placed behind whose output window diameter is designed for the 2D image plate Mar345 detector. The accessible q-range is qmin = 0.03 Å-1 to qmax = 3 Å-1. A special attention was given to the complete data treatment processing (absolute intensities, uncertainties, reference samples, calibration ,…), enable us to make traceable measurements. Combining molybdenum energy and the state-of-art experimental setup provide us with a very powerful tool for nanomaterial studies [2][3]. We present here some results obtained with this experiment for inter-laboratories characterization studies in particular of silver nanoparticles, and Si nanoparticles

PYSAXS, AN OPEN SOURCE PYTHON PACKAGE AND GRAPHIC USER INTERFACE FOR SAXS DATA TREATMENT

International audienc