Dynamic light scattering in a sponge phase of a nonionic surfactant

The fluctuation of bilayers in the sponge (L-3) phase of the binary mixture of a nonionic surfactant, pentaethylene glycol dodecyl ether (C12E5), and water is studied by the dynamic light scattering spectroscopy. In concentra ted solution, the autocorrelation function of the scattered light intensity shows almost a single exponential decay and the inverse of correlation tim e Gamma is proportional to the square of scattering wavevector q. In dilute solution, the autocorrelation function shows a stretched exponential decay and the dispersion of Gamma shows a crossover behavior from Gamma proporti onal to q(2) to Gamma proportional to q(3) as q increases. It is found that the dispersions of Gamma at various concentrations and temperatures can be scaled into the universal curve. The results for dilute solution are compa red with a recent theory concerning to the thermal fluctuation of membranes .