INTERFERENCE OF HEAVY-ATOM WITH MAGNETIC SPIN EFFECTS IN SPIN-CORRELATED MICELLAR RADICAL PAIRS

The recombination kinetics of the radical pairs 3(SeH. .. An.+), with SeH+ = selenine, An = aniline, and 3(TH. .. An.+) with TH+ = thionine, p-Cl-An = 4-chloroaniline, in benzene/cetyldimethylbenzylammonium chl oride/H2O reverse microemulsions was measured by ns-laser flash photol ysis as a function of magnetic field and nanodroplet size. By comparis on with the behaviour of the 3(TH. .. An.+) radical pairs evidence was provided that, besides the main route of triplet radical pair recombi nation through triplet to singlet spin conversion in situations when t he radicals are separate and subsequent reaction on re-encountering as singlet radical pair, there is a finite probability that radical pair s encountering with overall triplet spin will directly recombine throu gh electron transfer to singlet ground state products. The probability of this process, which is induced by spin-orbit coupling and is indep endent of a magnetic field, was evaluated for the three radical pairs specified above.