Small-angle X-ray scattering determination of the electron density of the particles in a colloidal suspension

Abstract

Two different small‐angle X‐ray scattering methods have been used to determine the electron density of the particles in a colloidal silica suspension. In the first method, the electron density of the particles was calculated from the measured change of the zero‐angle scattered intensity caused by the addition of known quantities of sucrose to increase the solvent electron density. In the second method, the scattering from the suspension was compared with the scattering from a nearly ideal gas. Within an experimental uncertainty of about 5%, the electron density of the silica particles was found by both methods to have a value corresponding to pure SiO2 particles with the mass density 2.28 g.cm−3 which is listed in the manufacturer's literature describing the suspensions. This determination of the electron density will enable these suspensions to be used as standard samples in determinations of the ratio of the scattered intensity to the incident intensity.

A unified theory of absolute intensity measurements in small-angle X-ray scattering

“…Instead of attempting to attenuate the direct beam and then measure its power directly, one can determine the absolute intensity calibration factor indirectly by measuring the scattered power from a sample of known differential cross section. Katz (1959), Weinberg (1963), Shaffer (1964), Shaffer & Beeman (1970), Patel & Schmidt (1971) and Sparks, Hendricks & Shaffer (1972) calibrated absolute intensities by measuring the scattering near zero angle for a variety of gases. It may be shown (e.g.…”

Investigating Macromolecular Complexes in Solution by Small Angle X-Ray Scattering

“…However, since the particles are randomly oriented (equation 6) and there is only a limited measurable region in reciprocal space, the information content in a SAXS curve is very low (Patel and Schimidt, 1971). Nevertheless, even with these limitations important developments occurred in the last decades have proof that it is possible to obtain a 3D model from the 1D SAXS curves.…”

An absolute intensity standard for small-angle X-ray scattering measured with position-sensitive detectors

“…In the past, the total integrated scattering from silica suspensions in water has been successfully used for the calibration of SAXS data using conventional counting techniques (Patel & Schmidt, 1971;Wada, Suzuki, Hiramatsu, Seto, Ichikawa, Kurita, Tagawa & Okano, 1970). The application of this technique to PSDs is discussed in this paper.…”

“…Utilization of these sols as standards depends solely on whether the electron density of the suspended silica particles is given by the electron density of amorphous silica (Patel & Schmidt, 1971). Consequently, electron densities of the suspended particles were determined using a secondary standard calibrated in our laboratory.…”