Luminescence Phenomena in Gamma-Irradiated Pure 3-Methylpentane Glass: Implications for Radiation Chemistry

Gamma irradiation of 3-methylpentane glass at 77°K causes prolonged luminescence at that temperature with a decay law resolvable into three first-order decays with specific rates of the order of 10—3 sec—1. Activation energies for the release of this ``isothermal'' luminescence are tightly grouped around a value near 0.1 eV. Additional luminescence produced in a ``warmup'' region corresponds to activation energies broadly grouped near 0.25 eV. Absorption of infrared light causes rapid release of ``isothermal'' luminescence but has no observable effect on ``warmup'' luminescence. Added quenchers affect both parts. The spectrum of the luminescence seems to be unaffected by the temperature or other treatment of the sample. Results are interpreted in terms of release of weakly trapped electrons and their interaction with positive holes to yield emitting states. The results suggest that in the radiation chemistry of condensed systems at room temperature some of the electron-neutralization processes require >10—11 sec for their completion. During this time the positive holes involved can react chemically with their environs.