Tunneling recombination luminescence of glassy polyethylene adipate γ-irradiated at low temperature and effect of electron scavengers

Abstract

The isothermal luminescence (ITL) from glassy polyethylene adipate (PEA) γ-irradiated at 77 K was observed over a long period of time, together with effect of the electron scavengers on it. The decay behavior of ITL is similar to that of polyethylene terephthalate or polycrystalline PEA obtained previously, so that the decay obeys the decay function I(t) = I₀/(1 + αt)^m. The detailed discussion on the parameters included in the decay function is given. Differences in the parameters between different materials or different physical states are found not to be very large, except the parameter I₀. Addition of biphenyl into PEA enhances considerably the intensity of ITL and causes the luminescence center to exchange from the ester cation into the biphenyl cation. In the biphenyl doped PEA, the possibility of the triplet-triplet energy transfer from the excited ester group to the biphenyl and the positive charge transfer from the ester cation to the biphenyl are shown.