Detection of small polydispersities by dynamic light scattering

Abstract

We consider dilute suspensions of optical and size polydisperse spherical particles for which the Rayleigh-Gans-Debye (RGD) approximation is valid. To develop the theory a concentric core-shell hard sphere model is adopted, in which particles possess a continuous variation in the core sizes but have constant shell thickness, thus giving rise to a distribution in the particle refractive indices. For two-component system, we theoretical analyze the dependence on scattering vector q of the average scattered intensity I(q) and the effective diffusion coefficient De(q) obtained from the first cumulant measured by dynamic light scattering in the case of the refractive index of the solvent and the refractive index of the shell are matched, i.e., nm equals ns. Under favorable conditions it should be possible to measure small polydispersities.© (1995) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.