Self-diffusion in two-dimensional binary colloidal hard sphere fluids

Abstract

We present a systematic experimental study of the dynamic behaviour of monodisperse and bidisperse two-dimensional colloidal hard sphere fluids. We consider the diffusive behaviour of the two types of particles for systems with a variety of compositions and total area fractions. In particular, we measure the short- and long-time diffusion coefficients for both species independently. We find that the short-time self-diffusion coefficients show an approximately linear dependence on the area fraction and that the long-time self-diffusion coefficients are well described by an expression dependent upon only the area fraction and contact value of the radial distribution function. Finally, we consider the effect of composition change and find some variation in the long-time self-diffusion coefficients, which we ascribe to the complex packing effects exhibited by binary systems