Luminescence in warming and cooling from γ-irradiated polyethylene

Anomalous luminescence during warming and cooling has been found in previously oxidized polyethylene following γ irradiation in air at room temperature. During warming, one of the thermoluminescence peaks appears at about 384 degreeK, close to the crystallite melting temperature. Further luminescence during a subsequent cooling appears, rising abruptly at about 370 degreeK near the recrystallization temperature. Such a luminescence is observable by repeating the warming and cooling cycle, although the luminescence intensity decreases with successive cycles. It appears that the presence of crystallites is essential for an appearance of the luminescence, and an existence of some long-lived trapped electrons above the melting temperature is suggested