Effective interaction potential obtained from experimental structure factors: The inverse problem

Abstract

The structure factor S(q) was measured for a colloidal dispersion of latex microspheres (40 nm of diameter) by both static and dynamic light scattering (using a Malvern Instruments spectrometer, λ=488 nm). The structure was formed for a sample of particle number density 2×10¹³ ml⁻¹. The interaction potential was determined from the experimental S(q) by means of the straightforward use of three different closures (Percus-Yevick, hipernetted chain, mean spherical approximation). Some difficulties found with this procedure (such as the cut-off effect) are discussed. However, these closures lead to very similar results. Furthermore, the results are tested and compared with the simulations based on a Yukawa potential.