Diffusion of interacting particles: Light scattering study of microemulsions

We have studied both the intensity and the autocorrelation function of the light scattered by water in oil microemulsions. A dilution procedure was used, which allowed us to extract from the experimental data information about droplet sizes and virial coefficients. It was found that in most cases, the droplets do not behave like hard spheres and that supplementary interactions must be taken into account. As pointed out recently by A. Vrij, these interactions can be treated as a perturbation to interpret the intensity data. Recent theoretical analyses of macromolecular diffusion allow one to interpret also the diffusion coefficient data. The agreement between theory and experiments is qualitatively good.