Interpretation of the structural parameters derived from the analysis of polymer colloids by small-angle X-ray and neutron scattering

We reconsider the analysis of the structure of colloidal particles by small-angle scattering. Special emphasis is laid on the structural parameters derived from a small-angle experiment conducted at different contrast. The forward scattering of the particles, their radius of gyration and the invariant are reconsidered in terms of a model introduced by Harrison (1969). Here the finite resolution of the experiment as well as the small size of the constituents of typical polymeric colloids are taken into account by definition of a shape function φ (r) which varies continuously between 0 and 1. Model calculations show that careful measurements of the scattering intensity over a wide range of scattering angles and contrasts may be used for a detailed analysis of the shape function.