An ESR Study of Intermediates in γ-Irradiated Methylcyclohexane and Isobutane Containing Benzene

The present work was undertaken in order to examine intermediates from benzene and toluene in γ-irradiated glassy methylcyclohexane (MCH) and polycrystalline isobutane matrices at 77°K. The γ-irradiation of MCH containing low concentrations of benzene gave an ESR spectrum with a good hyperflne resolution, which can be ascribed to the benzene anion, while at higher concentrations of benzene it gave an ESR spectrum with a poor resolution, which is attributable to the benzene monomer and dimer anions. On the contrary, the γ-irradiation of polycrystalline isobutane containing benzene did not yield an ESR spectrum which can be attributed to the benzene anion. However, the γ-irradiation of a mixed glass of isobutane and 4 mol% MCH containing benzene gave an ESR spectrum which is attributable to the benzene anion. The yield of trapped electrons in this system was three times as large as that in pure γ-irradiated MCH. Such a difference in the results between glassy MCH and polycrystalline isobutane matrices gives evidence of a phase effect on the radiolysis of solid hydrocarbon.