The evaluation of multiple X-ray small-angle scattering

The theory of multiple small-angle scattering is revised and extended to systems of arbitrary symmetry and structure. The principal difference between the evaluation of multiple scattering with and without observable primary beam is discussed and the values of the parameters related to the limits between single scattering and multiple scattering with and without observable residue of the primary beam are given for a number of porous materials. The applicability of the methods is demonstrated in a study of a sample of carbon black and a carbon fibre before and after potassium absorption.