Intramicellar energy transfer in aqueous CTAB solutions

We report an experimental study on the energy transfer process between perylene and fluorescein in cetyltrimethylammonium bromide (CTAB) micelles. The spectral behaviour and the dynamic and polarization data of dyes confirmed that perylene is solubilized in the inner hydrocarbon region of the micelle, while fluorescein is micellized in the inner part of the Stern region, The results obtained from the quenching experiments demonstrated that a static mechanism operates for the perylene-fluorescein pair in CTAB micelles. The study of the influence of the acceptor concentration on the energy transfer efficiency suggested that only intramicellar energy transfer contributes to the overall process. Moreover, the influence of the addition of 0.01 M NaOH on CTAB micelles was investigated by the changes in both the critical micelle concentration (CMC) and the micellar aggregation number. CMC values were obtained from the pyrene 1:3 ratio method, and micellar aggregation numbers were determined by using a procedure based on the energy transfer process.