Time-resolved fluorescence anisotropies in mixed surfactant solutions

Time-resolved fluorescence anisotropy decays of solutions of Triton X-114 ( TX-114) with various amounts of sodium dodecyl sulfate (SDS) were measured using the emission both from the surfactant itself and from added perylene. In the former case, the monomer and aggregate species of the surfactant we re spectroscopically isolated and were shown to have significantly differen t rotational correlation times. The rotational diffusion of perylene in mic ellar TX-114 with small amounts of added SDS appeared to have a component w ith a very short correlation time. The anisotropy decay curves showed the e xistence of limiting anisotropies (r(infinity)), indicating hindered probe rotation in the micellar environment. At higher SDS concentrations, the fas t-decaying component slowed down and the limiting anisotropy decreased subs tantially, suggesting some migration of the probe to the interior of the mi celle. (C) 1999 Academic Press.