Publication costs assisted by the U.S. Energy Research and Development AdministrationThe G values of trapped radicals produced by the y irradiation of polycrystalline n-alkanes at 77 K are independent of carbon number from C6 to C10, are -70% higher than in the glassy branched alkanes, and are -40% higher for the protiated forms than for perdeuterated. In an uncracked single crystal of n-C6H14, the G(R.) and decay kinetics are consistent with a rapid intraspur decay followed by second-order reaction of randomly distributed radicals, as observed in glasses, in contrast to the "stepwise" decays observed in polycrystalline samples. 30-35% of the radicals produced by y irradiation of protiated n-alkanes are removable by exposure to 254-nm light, compared to 18% or less in deuterated n-alkanes. Thermally reversible photoisomerization of the remaining radicals occurs. Both the photoinduced removal of radicals and the photoisomerization occur at 4 K as well as at 77 K. Ultraviolet absorption by carbanions formed by the capture of electrons by radicals in y-irradiated n-C6H14 has been observed, and an upper limit of 0.25 has been set on G(R-)initid. The carbanion concentration reaches a steady state after a dose of -2 x IO2" eV g '. Phase effects on G(R-) in polycrystalline cyclohexane have been examined.
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