Accurate Measurement of Small Polydispersities in Colloidal Suspensions

We demonstrate a simple method for the accurate characterization of the particle size distributions of colloidal particles with small polydispersities using a combination of dynamic light scattering and static light scattering. This method takes advantage of the variation in apparent radius observed using dynamic light scattering, as the scattering angle is increased through minima in the intensity form factor. Two-color dynamic light scattering is used to ensure there are no contributions from multiple scattering. We demonstrate that the poly(methyl methacrylate)-based particles used here have negatively skewed particle size distributions and in many cases can be characterized by a two parameter Weibull distribution. The importance of the accurate characterization of the particle size distribution for studies of crystallization in hard sphere colloidal suspensions is discussed.