Analysis of small angle neutron scattering spectra from polydisperse interacting colloids

TLDR

The paper proposes a simple procedure for analyzing small‑angle neutron scattering spectra from interacting colloids with a continuous size distribution. The method examines how polydispersity alters the apparent interparticle structure factor S′(Q) measured by SANS. The analysis reveals that polydispersity and orientational averaging damp oscillations in S′(Q) compared to the true structure factor, and the procedure is validated on microemulsions, micelles, and proteins.

Abstract

In this paper, we outline a simple procedure for analyzing small angle neutron scattering (SANS) spectra from interacting colloids containing a continuous distribution of particle sizes. In particular, the effects of polydispersity on the apparent interparticle structure factor S′(Q) observed by SANS is investigated. We find that the oscillations in S′(Q) are significantly damped in comparison to those of the true structure factor S(Q). When our procedure is extended to the analysis of SANS spectra from nonspherical particles, we find that orientational averaging affects S′(Q) in a qualitatively similar way. The applicability of the procedure to the analysis of real data is demonstrated with spectra taken from water-in-oil microemulsions, ionic micelles, and interacting proteins.