CROSSOVER FROM MEAN-FIELD TO 3-DIMENSIONAL ISING CRITICAL-BEHAVIOR INA 3-COMPONENT MICROEMULSION SYSTEM

Critical density fluctuations of water droplets in an oil-rich three-c omponent microemulsion system have been studied by small-angle neutron scattering as a function of temperature near and far from the boundar y of phase decomposition. The observed data in the one-phase region ar e well described in terms of the asymptotic crossover expression calcu lated by Belyakov ct al. The data are found exclusively in the crossov er region between the universality class of three-dimensional Ising an d mean field regimes. The Ginzburg number is found to be between one a nd two orders of magnitude less than that for low molecular weight liq uids.