Determination of interparticle forces by colloidal particle scattering: A simulation study

Colloidal particle scattering is a recently developed method for the determ ination of forces between micron-sized particles, which has given promising results. Inversion of the experimental scattering results to retrieve the interaction force requires the development of reliable computer code to mat ch theory and experiment. We review the method used, discuss some operation al details, and present some validating results for shear and sedimentation fields that compare favorably with the literature. We have used the simula tion to compare particle scattering in a simple shear field for a range of exponential surface forces and discuss the sensitivity of these results to changes in potential parameters. We also discuss the sensitivity in relatio n to sources of error and their magnitude. In particular, we have incorpora ted a Brownian dynamics algorithm and compared the level of thermal noise w ith a simple theoretical formula. We introduce a straightforward means of r epresenting the data and find that order of magnitude changes in the parame ters evoke changes in the scattering pattern roughly equivalent to the Brow nian noise level for a typical experiment with Pe = 120. The results demons trate the ability of the method, in principle, to distinguish between inter action potentials of different ranges and energy parameters. (C) 2000 Acade mic Press.