Ultrafast dynamics of water–AOT–octane microemulsions Original Research Article

The ultrafast dynamics of reversed micelles in ternary mixtures of water, AOT and octane was investigated using picosecond infrared pump–probe spectroscopy and dynamic light scattering. After excitation of the O–H stretching band of water transient spectral changes were observed up to 3 ns. The observed decays showed typically a stretched exponential behavior, and its mean decay velocity turned out to decrease with increasing AOT-to-water ratio, μ. The results indicate that the observed relaxation times monitor the thermal diffusion of the relaxed vibrational energy from the water within the reverse micelle into the solvent. There are also some hints that the micelle size determines the individual relaxation time, and that the stretched exponential behavior reflects, at least partially, the polydispersity of the microemulsions.