Electron trapping and luminescence mechanism in thermoluminescence of irradiated polycarbonate

Thermoluminescence of polycarbonate irradiated by electron beams was observed in order to investigate the trapping of electrons and the luminescence mechanism. The thermoluminescence glow curve is composed of three components. The peaks appear at −150°C (α peak), −120°C (β peak), and −30°C (γ peak). The α peak is attributed to recombination of cations with electrons released from trapping sites formed by carbonate groups. The β peak is attributed to small amounts of impurities. The γ peak is perhaps due to untrapping of electrons from the phenoxy anion. The luminescence intensity of the α peak is linearly dependent on the absorbed dose, and that of the β peak is approximately proportional to the cube of the dose. The appearance of these peaks is presumably closely related to local molecular motions.