A Nanosecond Laser Flash Photolysis Study of Intramicellar Reactions in the Erythrosin B/CTAB Aqueous System

Article abstract of DOI:10.1021/j100187a029

Both "fast", occurring within 1 μs after excitation, and "slow" reactions, occurring in the hundreds of microseconds time scale, were observed following erythrosin B triplet formation in the cationic micellar system cetyltrimethylammonium bromide (CTAB).The "fast" events are shown to occur in multiply occupied micelles and are assigned to bimolecular reactions.The "slow" ones, which have not been studied in detail, are due to first-order deactivation processes of the triplet occurring in singly occupied micelles.The effects of the excitation intensity and occupancy on the fast triplet decay, radical formation, and subsequent geminate recombination have been studied.The triplet disappears with observed rate constants ranging from 5.5 * 1E6 to 3.6 * 1E6 s^-1 while the formation of radicals has rate constants varying from 3.3 * 1E7 to 9.1 * 1E6 s^-1.Both in triplet decay and in radical formation the increase in rates occurs by increasing the excitation energy and occupancy.The identification of the precursor(s) of radicals is discussed.The geminal radical recombination has a rate constant of 2.1 * 1E6 s^-1.