Small Angle X-ray Scattering Instrument Research Articles

A small sample stretcher for in-situ small angle X-ray scattering measurement

A small sample stretcher for in-situ measurement of small angle X-ray scattering (SAXS) was developed, which consists of stretch, transmission, detection and control systems. The basic parameters of the stretcher are: tension ⩾ 400 N, 3 mm/min ⩽ stretching speed ⩽ 50 mm/min, sample length ⩽ 30 mm, stroke ⩾ 80 mm, and resolution = 50 μm. The stretcher is compact and has low stretching speed and convenient remote control. It is suitable for in-situ SAXS measurements on stretching of carbon fibers, polyethylene and other samples. Such measurement were carried out with high density polyethylene (HDPE) on the SAXS instrument at the 1W2A station of Beijing Synchrotron Radiation Facility (BSRF). The result verified the effectiveness of the stretcher.

Fast SAXS data at home--Your personal SAXS beamline

Small angle X-ray scattering (SAXS) is a useful technique for extracting structural information from biological samples in solution. Our SAXS instrument, the BioSAXS-1000, combines Kratky collimation with confocal optics to achieve maximum X-ray flux on the sample without beam shape corrections. Recently, we offered three new upgrades to the BioSAXS-1000: (1) 2.3 times more flux with the OptiSAXS optic, (2) automatic sample loading, and (3) automatic data analysis. Here, we evaluate the quality of SAXS data collected in short exposure times on the BioSAXS-1000 with these 3 upgrades by using X-rays supplied by an FR-X rotating anode X-ray generator. We measured a concentration series for each of several protein standards (lysozyme, HSA, etc.). Our results show that 1-minute exposures were sufficient to determine the basic structural parameters: radius of gyration, extrapolated intensity at zero angle, and molecular weight. The upgraded BioSAXS-1000 provides a beamline experience in the home laboratory.

In Situ Analysis of a Bimodal Size Distribution of Superparamagnetic Nanoparticles

The dispersed iron oxide nanoparticles of ferrofluids in aqueous solution are difficult to characterize due to their protective polymer coatings. We report on the bimodal size distribution of superparamagnetic iron oxide nanoparticles found in the MRI contrast agent Resovist, which is a representative example of commercial nanoparticle-based pharmaceutical formulations. The radii of the majority of the nanoparticles (>99%) range from 4 to 13 nm (less than 1% of the particles display radii up to 21 nm). The maxima of the size distributions are at 5.0 and 9.9 nm. The analysis was performed with in situ characterization of Resovist via online coupling of asymmetrical flow field-flow fractionation (A4F) with small-angle X-ray scattering (SAXS) using a standard copper X-ray tube as a radiation source. The outlet of the A4F was directly coupled to a flow capillary on the SAXS instrument. SAXS curves of nanoparticle fractions were recorded at 1-min time intervals. We recommend using the A4F-SAXS coupling as a routine method for analysis of dispersed nanoparticles with sizes in the range of 1-100 nm. It allows a fast and quantitative comparison of different batches without the need for sample preparation.

Size distribution analysis of colloidal gold by small angle X-ray scattering and light absorbance

The data measured by small angle X-ray scattering (SAXS) and the extinction spectra observed by spectroscopy were examined as the in situ measurements of the size distribution of gold nanoparticles and were compared with the results obtained from the photographs by a transmission electron microscope (TEM). The mean size can be estimated from the wavelength of the peak absorbance using Mie theory. However, the particle size distribution can only be estimated from fitting the calculated spectrum to the experimental one of the sample with above 30 nm diameter. On the other hand, the scattering data measured by a SAXS instrument can estimate the mean size from the slope of the Guinier plot, when the particle size distribution is narrow. In addition, the size distribution and mean size can be calculated by the experimental SAXS data when the log-normal or Schulz–Flory size distributions are assumed.

A New Small-Angle X-ray Scattering Instrument on the French CRG Beamline at the ESRF Multiwavelength Anomalous Scattering/Diffraction Beamline (D2AM)

A new small-angle X-ray scattering instrument has been set up on the D2AM-ESRF beamline. This modular instrument, which has the capacity to handle different sample environments (variable temperature and pressure), is designed for easy wavelength changes, i.e. for anomalous-scattering studies. This paper describes its design and discusses in some detail its positioning and alignment with respect to the focusing optics. The mirrors were found to be a major source of diffuse scattering, which was eliminated by rearrangement of the slit positions and refocusing of the optics. The present configuration yields a high flux (10~°photons s -~) and allows measurements down to q = 0.005 ~-1.

Small-angle x-ray scattering of graphite-ferric chloride intercalation compounds

Small-angle X-ray scattering (SAXS) data were collected for two samples of ferric chloride intercalated in pyrolytic graphite and a comparison specimen of pristine graphite. The work was done on the 10 m SAXS instrument at the National Center for Small-Angle Scattering Research, Oak Ridge, Tennessee, with the help of NCSASR staff member Dr. J.S. Lin. The experiment was run using Cu Kα radiation and a sample-to-detector distance of 2.2 m, so that the detector scanned an angular range of 3.4–37 mrad, representing momentum transfers, Q, of 0.014–0.15 Å −1. The samples were oriented with their planes normal to the beam axis, so the experiment was sensitive to inhomogeneities within the plane. The scattering patterns obtained were all roughly circular, indicating that the samples were isotropic. The two intercalated samples, C 14FeCl 3 and C 21FeCl 3, had almost identical patterns, scattering much more strongly than the pristine graphite. The graphite displayed scattering maxima at Q values of 0.044, 0.088, 0.11 and 0.13 Å −1. These peaks were present in broadened form in the intercalated samples. Radii of gyration were estimated by extrapolating the slope of the scattering curve to Q = 0, giving 140 (C 14FeCl 3), 145 (C 21FeCl 3) and 214 Å (graphite).