Light beating spectroscopy measurements of micelles mutual diffusion coefficient within oil in water microemulsions in the presence of sodium chloride

Using light beating spectroscopy we have measured the mutual diffusion coefficient of micelles within oil in water microemulsions in the presence of added NaCl. The experimental results have been explained by replacing the viscosity of the continuous phase, which appears in the diffusion coefficient of systems of interacting particles, by the viscosity of the microemulsion. They lead to a positive second virial coefficient linked with the electric charge of the micelles and, for the highest NaCl concentrations, to a micellar radius which is close to the radius deduced from osmotic pressure.