Effect of matrix on the formation of solvent radicals in the radiolysis of alkanes in the solid state at 77 K

Abstract The effect of the matrix on the radiolysis of 2,3-dimethylbutane, neopentane. 2,2-dimethylbutane, and isobutane in the solid state has been studied at 77 K by means of ESR spectroscopy. Though only the ·CH2CH-(CH3)CH(CH3)2 radical is formed by the γ-irradiation of 2,3-dimethylbutane in the I crystal, the CH3\overset·C(CH3)-CH(CH3)2 radical is formed by the γ-irradiation of 2,3-dimethylbutane in the II crystal. Though the t-C4H9 and neo-C5H11 radicals are formed by the γ-irradiation of pure neopentane, the formation of radicals is affected appreciably by the addition of a small amount of alkanes. When neopentane containing ethane, etc. is γ-irradiated, the solute radical is mainly formed by energy transfer form the γ-irradiated neopentane to the solute. Most of the solutes have a spherical molecular structure like that of neopentane or are smaller than neopentane. When neopentane containing 3-methylpentane, etc. is γ-irradiated, only the neopentyl radical is formed. The molecular structures of the solutes are very different from that of neopentane. The formation of the solvent radical in the radiolysis of 2,2-dimethylbutane is affected by the addition of 3-methylpentane or methylcyclphexane. The formation of the butyl radical in the radiolysis of isobutane is also changed drastically by addition of alkanes. It is concluded that the formation of solvent radicals in the radiolysis of solid alkane is appreciably affected by the conditions of the matrix.