DIRECT STRUCTURE-ANALYSIS OF SMALL-ANGLE SCATTERING DATA FROM POLYDISPERSE COLLOIDAL PARTICLES

Citation
R. Mittelbach et O. Glatter, DIRECT STRUCTURE-ANALYSIS OF SMALL-ANGLE SCATTERING DATA FROM POLYDISPERSE COLLOIDAL PARTICLES, Journal of applied crystallography, 31, 1998, pp. 600-608
Citations number
23
Categorie Soggetti
Crystallography
ISSN journal
00218898
Volume
31
Year of publication
1998
Part
4
Pages
600 - 608
Database
ISI
SICI code
0021-8898(1998)31:<600:DSOSSD>2.0.ZU;2-W
Abstract
The internal structure of colloidal particles of spherical, rod-like o r lamellar symmetry can be determined from small-angle scattering data by means of the well established 'indirect Fourier transformation' te chnique followed by the numerical deconvolution of the pair distance d istribution function. The method works without any preliminary knowled ge of the particles under investigation except a rough estimate of the ir maximal size. However, its use has hitherto been restricted to mono disperse or very weakly polydisperse systems. In this paper a new meth od is presented that is capable of determining the radial scattering l ength density distribution of particles in strongly polydisperse sampl es and provides a parameter that quantifies the degree of polydispersi ty present in the system. The only additional information necessary is the function type which describes the size distribution of the partic les under investigation in the best way possible. However, the method is limited to polydisperse systems which may be characterized by only one linear size parameter. In addition, it is now possible to represen t the density profile by smooth spline functions, ie. the technique is no longer restricted to step functions as basis functions. The mathem atical procedure is outlined in detail and numerical results of simula tions as well as of experimental data from small-angle neutron scatter ing and small-angle X-ray scattering measurements of surfactant aggreg ates in water and water/oil systems are given.