The effect of an external magnetic field on the radiation-induced fluorescence of tricosane (n-C23H48), doped with luminophore, was studied on the nanosecond timescale. It was found that the characteristic frequency of quantum beats caused by the difference between the Zeeman interactions of dopant radical anions and tricosane radical cations increased substantially upon transition from the liquid to the crystal phase. Experimental data were in agreement with both the quantum-chemical calculations and theoretical spin evolution simulations, assuming that hyperfine couplings and transverse components of the tricosane radical cation g-tensor were averaged out by degenerate positive charge transfer in the tricosane crystal.