PULSE-RADIOLYSIS OF HYDROCARBON GLASSES AT 6-K AND 77-K

Several hydrocarbon glasses have been studied by pulse radiolysis at 6 and 77 K. The ratio of the initial yield of trapped electrons, G(et-), at 6 K to the initial yield at 77 K was found to be 0.81 for 3-methylpentane (3MP), 0.97 for 2-methylpentane (2MP), 0.80 for 3-methylhexane, 0.93 for methylcyclohexane (MCHx), 1.0 for 3-methyloctane (3MO), and 1.0 for 2,4-dimethylpentane. These results, together with the smaller ratios measured at long times for 3MP, 2MP, and MCHx, lead us to conclude that more decay of et- between 100 ns and minutes takes place at 6 than at 77 K. Slower trap deepening at 6 K compared to 77 K, which would lead to more electron tunneling at 6 than 77 K, could account for the results. The initial spectra of et- at 6 K are red-shifted compared to 77 K for 3MP and 2MP; the other hydrocarbons have the same maxima at both temperatures. The positive ion of 3MO is considerably more stable in the glass than in the liquid phase at 127 K. © 1979 American Chemical Society.