NONADIABATIC TRANSITIONS IN LIQUID-PHASE REACTIONS - NET ELECTRON POLARIZATION IN RADICAL PAIR RECOMBINATION AND TRIPLET-RADICAL QUENCHING

The nonadiabatic transitions leading to the net chemically induced dyn amic electron polarization (NCIDEP) in radical-radical (RR) recombinat ion and triplet-radical (TR) quenching are analyzed in detail. The the ory treating the transitions induced by both the fluctuating and the n onfluctuating interactions in a unified manner is developed. The discu ssed nonadiabatic mechanism of NCIDEP generation can be considered as an extension of the well-known ST_-mechanism. Simple analytical formul as for NCIDEP are derived which are applicable in different regions of parameters of the model suggested. It is shown that the fluctuating ( anisotropic) hyperfine interaction (hfi) can make significant contribu tion to NCIDEP RR-recombination which is comparable with the contribut ion of nonfluctuating (isotropic) Rhfi. The fluctuating zero-field spl itting interaction dominates the generation of NCIDEP in TR-quenching. Contribution of the fluctuating interaction appears to strongly depen d on the correlation time of fluctuations. Theory predicts essentially different dependencies of the contributions of fluctuating and nonflu ctuating interactions on the viscosity of a solution. The difference c an easily be distinguished experimentally.