The initial radiation-chemical yields of consumption of hydrocarbons G(0)(-RH), where RH is 5-vinyl-2-norbornene, 2-ethylidene-2-norbornene, or 2-vinylnorbornane, dissolved in the solvents (L) cyclohexane, carbon tetrachloride, tert-butylamine, and benzene during irradiation of their solutions at 40A degrees C with Co-60 gamma-rays were determined. The G(0)(-RH) values were found to be linearly related to the first vertical ionization potentials (PI1) measured for RH and L in the gas phase by means of photoelectron spectroscopy. It was shown that the RH consumption processes are controlled by species with the highest and lowest PI1 values. It was concluded that these species are superexcited solvent molecules L** (PI1 = 15.6-17.8 eV for cyclohexane) and isomeric (distonic) forms of the RH+ radical cations, not the parent L and RH molecules, respectively. In the case of RH = VNB, the radical cation in this form contains two allyl systems, of which one is cationic and the other (characterized by PI1 = 7.1 eV) is radical.