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Scattering Patterns (scattering + pattern)
Selected AbstractsIn situ Grazing Incidence Scattering Investigations During Magnetron Sputtering Deposition of FePt/Ag Thin Films (Adv. Eng.ADVANCED ENGINEERING MATERIALS, Issue 6 2009Mater. The cover picture shows an grazing incidence small angle X-ray scattering pattern of a granular Ag(6nm)-FePt(7.5nm)-Ag-FePt thin film using an in-situ magnetron sputtering chamber measured directly after growth at the Beamline BM20 (ROBL) at the ESRF. The sequential deposition provides separated, faceted FePt nanoislands without any magnetic property degradation and with magnetic moments preferentially oriented parallel to layer surface. The central part of the picture was blocked by a beam stop to avoid an over-saturation of the CCD detector. More details can be found in the article by Jörg Grenzer et al. on page 478. [source] Inverse problem of theory of the laser irradiation scattering in two-dimensional irregular integrated optical waveguide in the presence of statistic noiseLASER PHYSICS LETTERS, Issue 2 2005A. A. Egorov Abstract The linear inverse problem of the theory of the light scattering in two-dimensional integrated optical waveguide with statistical irregularities in presence of noise (non exact data) is investigated. The approximated correct solution of the inverse problem of the theory of waveguide scattering in hand is obtained for the natural physic and mathematics restrictions of imposed on a "measured" scattering pattern. The algorithm of restoring an autocovariance function of waveguide irregularities is based on a combination of classic regularization and quasi-optimal filtration. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] X-ray characterization of epi-Ge/Pr2O3/Si(111) layer stacks by pole figures and reciprocal space mappingPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2009Peter Zaumseil Abstract An epi-Ge/Pr2O3/Si(111) layer structure prepared by consecutive steps of epitaxial deposition and annealing is used to demonstrate the possibility of a complex characterization by combination of different X-ray diffraction techniques. Especially pole figure measurements, reciprocal space mapping (RSM) and high resolution (HR) ,/2, scans at selected inclined netplanes were successfully used to determine the in-plane lattice orientation of the layers relative to the substrate, the strain state of all layers and the structural perfection of the epi-Ge film. It was found that the major part of the epi-Ge layer has the same type A stacking orientation as the Si substrate, but about 0.6% is of type B. The Pr2O3 buffer layer exhibits type B only. The strain state of oxide and epi-Ge was determined, and a small difference in the lattice constant of type A and B epi-Ge was found. Microtwins lying in inclined {111} planes were unambiguously identified by pole figure measurements as the dominating structural defects in the epi-Ge layer. They cause a characteristic scattering pattern in reciprocal space maps. The proposed combination of X-ray techniques allows a relatively fast, integral and non-destructive analysis of heteroepitaxial semiconductor oxide semiconductor structures. [source] Online light scattering measurements: A method to assess morphology development of polymer blends in a twin-screw extruderPOLYMER ENGINEERING & SCIENCE, Issue 10 2002G. Schlatter Light scattering has proved itself an efficient technique to determine particle diameters in heterogeneous dilute dispersions in the micrometer range. Extrusion of polymer blends is expected to give rise to very small particles, typically in the range from hundreds of nanometers to tens of micrometers. A light scattering device developed in our laboratory has been used to study the morphology of polymer blends obtained in a twin-screw extruder. The main advantage of this technique is the immediate response obtained without any surface or interface modification that can occur during the sample preparation by using more conventional techniques like electron microscopy. To show the possible applications of this light scattering device, preliminary tests have been carried out. First, we present a comparison between experimental measurements and theoretical results for dilute systems. Second, we have investigated the effect of shear flow on the droplet deformation. Finally, we have studied the variations of the light scattering pattern for a reactive blend. [source] The electron-spin,nuclear-spin interaction studied by polarized neutron scatteringACTA CRYSTALLOGRAPHICA SECTION A, Issue 6 2007Heinrich B. Stuhrmann Dynamic nuclear spin polarization (DNP) is mediated by the dipolar interaction of paramagnetic centres with nuclear spins. This process is most likely to occur near paramagnetic centres at an angle close to 45° with respect to the direction of the external magnetic field. The resulting distribution of polarized nuclear spins leads to an anisotropy of the polarized neutron scattering pattern, even with randomly oriented radical molecules. The corresponding cross section of polarized coherent neutron scattering in terms of a multipole expansion is derived for radical molecules in solution. An application using data of time-resolved polarized neutron scattering from an organic chromium(V) molecule is tested. [source] Cover Picture: Bistable Nematic Liquid Crystals with Self-Assembled Fibers (Adv. Mater.ADVANCED MATERIALS, Issue 6 20056/2005) Abstract The cover shows a recording process using nematic liquid crystal alignment. On p.,692, Kato and co-workers report that reversibly bistable states have been achieved for nematic liquid crystals incorporating a small amount of self-assembled fibers. Homeotropic monodomains and non-aligned multidomains can be fixed and switched by thermal treatment in electric fields. The technique is applied to the formation of rewritable light scattering patterns, as shown on the cover. [source] Multiphase approximation for small-angle scatteringJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2010Dragomir Tatchev The two-phase approximation in small-angle scattering is well known and is still the dominant approach to data analysis. The intensity scattered at small angles is proportional to the second power of the difference between the scattering densities of the two phases. Nevertheless, scattering contrast variation techniques are widely used, and they are obviously suitable for multiphase systems or systems with gradually varying scattering density, since if no parasitic scattering contributions are present the scattering contrast variation would only change a proportionality coefficient. It is shown here that the scattered intensity at small angles of a multiphase system can be represented as a sum of the scattering of two-phase systems and terms describing interference between all pairs of phases. Extracting two-phase scattering patterns from multiphase samples by contrast variation is possible. These two-phase patterns can be treated with the usual small-angle scattering formalism. The case of gradually varying scattering density is also discussed. [source] Elucidation of zeolite microstructure by synchrotron X-ray diffuse scatteringJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 2 2004B. J. Campbell Single-crystal diffuse scattering measurements can now rapidly probe the three-dimensional structure of subtle defects in microporous framework materials. Diffuse scattering data from natural mordenite crystals are shown to exhibit a complex distribution of weak features which have been mapped out using a synchrotron X-ray source and a CCD detector. Comparison with computer-simulated diffuse scattering patterns yields a detailed three-dimensional columnar defect structure and reveals that roughly one third of the mordenite's columnar defects cooperate to form a block-mosaic pattern of {110} stacking faults. [source] Benefits of polarized small-angle neutron scattering on magnetic nanometer scale structure modelingJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003André Heinemann Recent use of polarized neutron technique in small-angle scattering (SANS) have led to impressive results in the case of magnetic nanometer-scale structure analysis. In some particular cases this method offers the possibility to survey structure models with the necessary accuracy for the first time. The different cross sections for spin-up and spin-down neutron scattering on magnetic precipitates can be combined with the method of chemical contrast variation. All data fitting using structure models will benefit of that kind of constraints. The analysis of the interference term of nuclear and magnetic scattering respectively enables the extraction of additional information about the composition and magnetization profiles of the samples. Here we place emphasis on the difference of spin-up and spin-down neutron scattering intensities to obtain this information. This technique profits by the clear distinction between magnetic and nonmagnetic scattering contributions and the strong auxiliary conditions for model fitting procedures. Depending on the relative orientations of the external magnetic field, the local magnetization of the precipitates and the scattering vector, significant scattering patterns can be scrutinized. Beside general formulas for some special cases of present experimental interest we exercise the approach to a nontrivial case of data obtained from polarised SANS experiments at the Berlin Neutron Scattering Center (BENSC). [source] The change in characteristics of microcrystalline cellulose during wet granulation using a high-shear mixerJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 5 2001Tatsuya Suzuki The objective of this study was to investigate the mechanism of hard granule formation and to demonstrate the applicability of X-ray diffraction methods for studying the polymeric pharmaceutical excipients. Using a high-shear mixer, microcrystalline cellulose (MCC) was granulated with water as the granulating liquid. The hardness of the MCC granules increased with granulation time and the amount of water added. The specific surface area measured by the N2 adsorption method was reduced during the process. Crystallite size of cellulose, calculated by Scherrer's equation adapted for wide angle X-ray diffraction method, decreased with granulation time and with increasing amounts of water added. Debye plots for X-ray small scattering patterns suggested that the average magnitude of the continuous solid region in MCC granules became significantly greater, whereas the specific surface area of the MCC granules, calculated from Debye plots, became smaller in comparison with that of intact MCC. These findings suggested that the long-chain structures in MCC were disrupted, resulting in smaller units with shorter chain lengths due to the strong shear force of the impeller. These smaller units then form a network within the granules. Thus, MCC granules are strengthened with longer granulation time and greater amounts of water, resulting in a more intricate network. The change in MCC chain length and physical structure can be experimentally detected using the small-angle X-ray scattering and wide-angle powder X-ray diffraction methods. [source] Synthesis and characterization of a poly(GMA)-graft-poly(Z- L -lysine) graft copolymer with a rod-like structureJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 18 2009You-Liang Tu Abstract This study applied the macromonomers and glycidyl methacrylate (GMA) to synthesize a series of the graft copolymers, poly(GMA)-graft-poly(Z- L -lysine), and investigated the conformation of the graft copolymer. The graft copolymers were synthesized with different GMA monomer ratios (28 to 89%) and different degrees of polymerization (DP) (8 to 15) of the poly(Z- L -lysine) side chain to analyze secondary structure relationships. Atomic force microscopy (AFM), Fourier transform infrared spectroscopy (FTIR), and both wide angle and small angle X-ray scattering spectroscopy (WAXS, SAXS) were used to investigate the relationship between the microstructure and conformation of the graft copolymers and the different monomer ratios and side chain DP. In AFM images, n8-G89 (the graft copolymer containing 89% GMA units and the macromonomer DP is 8) showed tiny and uniform rod-like structures, and n14-G43 (the graft copolymer containing 43% GMA units and the macromonomer DP is 14) showed uniform rod-like structures. FTIR spectra of the graft copolymers showed that the variations of ,-helix and ,-sheet secondary structures in the graft copolymers relate to the monomer ratios of the graft copolymers. However, the X-ray scattering patterns indicated that the graft copolymer conformations were mainly dependent on the poly(Z- L -lysine) side chain length, and these results were completely in accordance with the AFM images. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4655,4669, 2009 [source] High-resolution wide-angle X-ray scattering of protein solutions: effect of beam dose on protein integrityJOURNAL OF SYNCHROTRON RADIATION, Issue 5 2003Robert F. Fischetti Wide-angle X-ray scattering patterns from proteins in solution contain information relevant to the determination of protein fold. At relevant scattering angles, however, these data are weak, and the degree to which they might be used to categorize the fold of a protein is unknown. Preliminary work has been performed at the BioCAT insertion-device beamline at the Advanced Photon Source which demonstrates that one can collect X-ray scattering data from proteins in solution to spacings of at least 2.2,Å (q = 2.8,Å,1). These data are sensitive to protein conformational states, and are in good agreement with the scattering predicted by the program CRYSOL using the known three-dimensional atomic coordinates of the protein. An important issue in the exploitation of this technique as a tool for structural genomics is the extent to which the high intensity of X-rays available at third-generation synchrotron sources chemically or structurally damage proteins. Various data-collection protocols have been investigated demonstrating conditions under which structural degradation of even sensitive proteins can be minimized, making this technique a viable tool for protein fold categorization, the study of protein folding, unfolding, protein,ligand interactions and domain movement. [source] | ||||||||||||||||