| Abstract
| - Dielectric relaxation behavior of spherical micelles of cationic surfactants, dodecyltrimethylammoniumbromide, tetradecyltrimethylammonium bromide, and cetyltrimethylammonium bromide, in aqueoussolution was examined in the frequency range from 106 to 109 Hz. Each surfactant solution shows pronounceddielectric dispersions with two distinct relaxation times above the critical micelle concentrations. A slowrelaxation mode with a relaxation time τs ∼ 5 ns reduced its magnitude with increasing the concentrationof surfactants (CD). On the other hand, the magnitude of a fast relaxation mechanism with the relaxationtime τf ∼ 0.5 ns was proportional to CD. The slow relaxation mode was attributed to the fluctuation ofa counterion distribution around the spherical micelle or that of a distribution of dissociated cationicsurfactant headgroups on the micellar surface. The fast relaxation mode was assigned to the rotationalmotion of ionic pairs consisting of surfactant cations and counteranions in the spherical micelle.
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