Time-resolved epr studies of photo-initiated electron transfer and spin dynamics of porphyrin/quinone mixtures in micellar systems

We report on time-resolved EPR experiments of the photo-induced electron transfer from zinc-tetraphenylporphyrin (ZnTPP) to duroquinone (DQ) in cationic CTAC and neutral Triton X-100 micelles. The spin-polarized EPR spectra and their time-dependence indicate pronounced differences between the two micellar systems: In the neutral micelles, the lifetime of the spin-correlated radical pair is longer than in the charged micelles. In the CTAC system an unusual temperature dependence of the polarization pattern is observed. This can be attributed to the effects of both the microviscosity of the micellar interior and the macroviscosity of the bulk solution on the spin dynamics of the reactants located inside the micelles.