Radiation-induced luminescence of PET and PEN films under MeV ion and pulsed UV laser irradiation

Ion- and photo-induced luminescence of polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) films was investigated during irradiation by MeV H and He ions and an ultraviolet pulsed laser. At the beginning of ion irradiation, the PEN film emitted blue luminescence, whose intensity was an order of magnitude higher than that emitted by the PET film. Successive ion irradiation effectively reduced the luminescence centers, and the rate of decease in luminescence intensity depended on the energy deposited along the trajectory of the ions. Optical absorption measurements in the infrared region revealed an irradiation-sensitive feature of the PEN film. Moreover, a photo-induced band grew remarkably at 470 nm in the PET film under 266 nm pulsed laser irradiation, while the PEN film showed a moderate decrease in luminescence intensity at 440 nm.