TRIPLET-TRIPLET ANNIHILATION IN MICELLES INCLUDING TRIPLET INTERMICELLAR MIGRATION

The problem of triplet-triplet annihilation in micelles is analyzed under conditions where triplet molecules are mobile species migrating between micellar confinements. Using a stochastic treatment, it is demonstrated that the tripler decay is characterized by a faster component due to the intramicellar annihilation followed by a slow component ascribed to the intermicellar migration and self-decay of the triplets. The slow process can be properly fitted by a decay function resulting from a competition of second-order and first-order processes of the classical chemical kinetics. The method is extended to experimental data obtained from laser flash photolysis of safranine in sodium dodecyl sulfate (SDS) solution. Analysis of triplet decays of the monoprotonated safranine at several different dye concentrations in 10 mM SDS, pH = 10 and ionic strength 0.1, yields a triplet mean residence time of about 10.4 +/- 2.7 mu s. The tripler decay time of the dye in these experimental conditions is 23.4 +/- 2.2 mu s.