Radical production in the radiolysis of liquid benzene

Iodine scavenging techniques have been used to examine the role of the phenyl radical in the radiolysis of benzene with γ-rays. Biphenyl, the main product in the radiolysis of neat benzene, and iodobenzene yields were determined as a function of iodine concentration. The yield of biphenyl in neat benzene is found to be 0.075 molecules/100 eV and independent of dose up to 1 Mrad. The addition of 0.1 mM iodine increases the biphenyl yield to about 0.4 molecules/100 eV. This increase is thought to be due to a reaction of iodine with the phenyl radical–benzene adduct, which apparently has a very long lifetime. Further addition of iodine leads to a decrease in biphenyl to about 0.09 molecules/100 eV at 30 mM iodine. This decrease is accompanied by an increase in iodobenzene from 0.04 to 0.32 molecules/100 eV. It appears that iodine can effectively compete with benzene for scavenging phenyl radicals.