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Scattered Intensity (scattered + intensity)
Selected AbstractsA high sensitivity pinhole camera for soft condensed matterJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3-1 2003Thomas Zemb 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 "separated optics" camera described in this paper 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 semi-transparent beam-stop. In pinhole geometry, the flux corresponds to a ca. 107 photons/s through the sample, collimated to q=10 -2 Å -1 in scattering vector range. This allows determination of scattered intensities of the order of 10 -3 cm -1, corresponding to the scattering related to isothermal compressibility of less than 0.1 mm of pure water. Values of absolute intensities for water as well as convenient widespread buffer solutions are shown, in order to be usable for calibration as secondary standards. As solid reference sample, the widely studied Lupolentm, a semi-crystalline polymer- is calibrated. The high- q limit (q, 4.5 nm,1 ) of a porous calcite sample can be used as a secondary standard for specific area determination of solid/solid or solid-liquid dispersions. [source] Direct detection of the protein quaternary structure and denatured entity by small-angle scattering: guanidine hydrochloride denaturation of chaperonin protein GroELJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 1 2002Yasutaka Seki A change in the higher-order structure of an oligomeric protein is directly detectable by small-angle scattering. A small-angle X-ray scattering (SAXS) study of the denaturation process of the chaperonin protein GroEL by guanidine hydrochloride (GdnHCl) showed that the disappearance of the quaternary structure can be monitored by using a Kratky plot of the scattered intensities, demonstrating the advantage of the SAXS method over other indirect methods, such as light scattering, circular dichroism (CD), fluorescence and sedimentation. The collapse of the quaternary structure was detected at a GdnHCl concentration of 0.8,M for a solution containing ADP (adenosine diphosphate)/Mg2+(2,mM)/K+. From pairwise plots of the change in forward scattering intensity J(0)/C (weight-average molecular weight) and the z -average (root mean square) radius of gyration against the GdnHCl concentration, the stability and nature of the denatured protein can be determined. The SAXS results suggest that the GroEL tetradecamer directly dissociates to the unfolded coil without going through a globular monomer state. The denatured ensemble is not a single unfolded monomer coil particle, but some mixture of entangled aggregates and a monomer of the coil molecules. Small-angle scattering is a powerful method for the detection and study of changes in quaternary and higher-order structures of oligomeric proteins. [source] The Role of Strain in New Semiconductor DevicesADVANCED ENGINEERING MATERIALS, Issue 4 2009Alex Dommann HRXRD is a very sensitive and non destructive technique to determine the strain in thin layer materials such as electron guides or the strain induces by the second order package of SOCs. In reciprocal space mapping (RSM), it is possible to separate the elastic component of the scattered intensity from the diffuse one. As a consequence, it is possible to study diffuse scattering due to defects of the crystal lattice. As an example we show also RSM's of a high-speed SiGe pMOS structure. [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] A novel multi-detection technique for three-dimensional reciprocal-space mapping in grazing-incidence X-ray diffractionJOURNAL OF SYNCHROTRON RADIATION, Issue 6 2008M. Schmidbauer A new scattering technique in grazing-incidence X-ray diffraction geometry is described which enables three-dimensional mapping of reciprocal space by a single rocking scan of the sample. This is achieved by using a two-dimensional detector. The new set-up is discussed in terms of angular resolution and dynamic range of scattered intensity. As an example the diffuse scattering from a strained multilayer of self-assembled (In,Ga)As quantum dots grown on GaAs substrate is presented. [source] SAXSANA: an interactive program for the analysis and monitoring of static and time-resolved small-angle X-ray solution scattering measurementsJOURNAL OF SYNCHROTRON RADIATION, Issue 2 2003Yuzuru Hiragi An interactive analytical program, SAXSANA, for small-angle X-ray scattering measurements of solutions is described. The program processes scattered data without disciplined knowledge of small-angle scattering. SAXSANA also assists in finding the best experimental conditions, thus avoiding blind runs of experiments. SAXSANA consists of the following procedures: (i) determination of the centre of scattered X-rays and moment transfer Q (Q,=,4,sin,/,, where 2, is the scattering angle and , is the wavelength) for each measured channel; (ii) conversion of the data format to the format of Q versus scattered intensities J(Q); (iii) truncation of unnecessary data and smoothing of scattering curves by cubic-spline function; (iv) correction of the absorption effect and subtraction of the scattered intensity of the buffer (solvent) solution from that of the sample solution; (v) creation of a data file for a three-dimensional representation of time-resolved scattering curves; (vi) determination of radii of gyration by Guinier plots; (vii) determination of persistent lengths by Kratky plots; (viii) extrapolation of the small-angle part by Guinier plots; (ix) extrapolation of the wide-angle part by Porod's & Luzzati's laws for the Hankel transformation in order to obtain the distance distribution function p(r); (x) calculation of p(r) and computation of the invariant, the chord length, the volume, the spherical radius, the maximum dimension Dmax and the radius of gyration (Rg). SAXSANA also serves as an on-site monitor for the validity of an experimental result during the measurements. [source] | ||||||||||