A new method for the evaluation of small-angle scattering data

Abstract

A new numerical method is presented for simultaneous smoothing, desmearing and Fourier transformation of X-ray and neutron small-angle scattering data. The method can only be applied to scattering curves from dilute particle systems, i.e. for scattering media whose distance distributions are zero beyond a certain value. The distance distribution of the scattering medium is approximated by a linear combination of about 20 to 30 cubic B-splines. These spline functions have a restricted extension in real space. Their coefficients are adjusted by a weighted least-squares operation so that the series, after being Fourier transformed and smeared according to the geometry and wavelength distribution, represents an optimum smoothed approximation of the experimental data. Tendencies towards oscillations in the least-squares operation are suppressed by a new stabilization routine. The method offers a new possibility for the estimation of the radius of gyration, which is generally superior to the Guinier approximation.

Colloidal Characterization and Thermodynamic Stability of Binary Eye Lens Protein Mixtures

“…To improve the statistics, averages over 300 different wave vectors q of the same modulus q were also performed. The experimental form factors were fitted using indirect fourier transformation 43 (IFT) to get rid of the experimental noise at high q and Guinier fit to have access to low q vectors. 44 The results are shown in Figure 2.…”

Small‐angle X‐ray study of aggregates of DNA‐dependent RNA polymerase from Escherichia coli

“…This plot should yield a straight line, the slope of which is proportional to the square of the radius of gyration. After desfiaearing [9] the radius of gyration was calculated to be R = 7.96 +-0.1 nm (holoenzyme dimer) and R = 13.5 +-0.2 nm (core enzyme oligomer). These values agree with the values computed from the p(r) function [8].…”

Effect of iron oxide loading on magnetoferritin structure in solution as revealed by SAXS and SANS

“…The shell in this case is no longer a monodisperse object, and now, in addition to the structural polydispersity, the size polydispersity contributes to the scattering as well. The partial disassembling of the shell is indirectly confirmed by modelling the scattering curves by indirect Fourier transform (IFT) [28], using the GNOM program [29], which represents the scattering data in terms of the pair distance distribution function (PDD) (see inset to Fig. 1).…”