Influence of molecular structure and temperature on trapped electron yields in γ-irradiated hydrocarbon glasses. Trapped electron decay in 2,4-dimethylpentane at ?22 K

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Abstract
G values (100 eV yields) determined in this work, and taken from the literature, for the production of trapped electrons by γ irradiation of 18 hydrocarbon glasses at 77 K range from 0.02 to 1.1. Small changes in molecular structure of the matrix molecules, such as the differences between 2‐methylpentane, 3‐methylpentane, and 3‐ethylpentane are often accompanied by large changes in G (e−t). It appears that the effects of molecular structure must be attributed either to differences in the concentration of sites which favor trapping in competition with reaction with cations or radicals, or to the influence of molecular structure and matrix structures on tunneling probabilities. The G (e−t) values for six hydrocarbons at 4 K are in each case lower than at 77 K. Electrons produced in 2,4‐dimethylpentane (2,4‐DMP) glass at 4 K by γ irradiation decay at 22 and 13 K and with the same rate, implying a tunneling mechanism. Electrons produced in 2,4‐DMP at 77 K and observed at 77 K decay more slowly, presumably because of the greater average trap depth. No observable electron decay occurs at temperatures G (e−t) values for glassy solutions of cyclopentane in methylcyclohexane increase with increasing cyclopentane concentration over the range of 1.5–57 mol%.