[en] New method of determining the singlet-triplet ratio during recombination of ion-radical pairs, based on registration of quanta oscillations in fluorescence, is proposed. The quanta oscillations were studied for cyclic, linear and branched alkanes by various concentrations of diphenyl sulfide hole acceptor. ⁹⁰ Sr - ⁹⁰ Y with ∼ 5 μCi activity was the source of ionizing radiation. The study on fluorescence decay kinetics was carried out in magnetic fields of 9600, 4800 and 2400 Gs. The decay within the error limits is linear. The share of heminal pairs for the studied solvents varies within the frames of 0.35-0.54