Effect of Phase on Excitation Transfer in the Radiolysis of Isobutane

The effects of CCl4 on the formation of H2 and C4H9 radicals in the radiolysis of i-C4H10 have been studied in glass at 77°K and the liquid at 195°K. The yield of H2, which is not affected by the addition of N2O or SF6, decreases sharply upon the addition of CCl4 in the glass, as in the crystal (This Bulletin, 42, 1164 (1969); 43, 1017 (1970).), while it does not so sharply decrease in the liquid as in the solid. The effects of CCl4 on the yields of H2 correspond fairly well to those on the yields of the C4H9 radicals. The effects of CCl4 in the glass are explained by the excitation transfer from the excited butane molecule to CCl4, as in the radiolysis of i-C4H10 in the crystal. A kinetic treatment suggests that its mechanism may be the exciton transfer. Some remarks on the primary process of ionization in the radiolysis of solid hydrocarbons are given from the viewpoint of exciton transfer.