Manifestation of quantum coherence upon recombination of radical ion pairs in weak magnetic fields. Systems with equivalent nuclei

Magnetosensitive radiofluorescence has been used to study the magnetic field effect at fields of the order of hyperfine ones during the recombination of spin-correlated radical ion pairs in non-polar solutions. For radical pairs, in which hyperfine interactions are essential only for equivalent nuclei in one of the pair partners, additional local maxima of fluorescence intensity in characteristic ‘multiple’ fields were observed. These maxima arise from the coherent nature of the radical pair initial state: different stationary states interfere in the fields where energy levels of the radical pair cross.