Changes in the optical energy gap and ESR spectra of proton-irradiated unplasticized PVC copolymer and its possible use in radiation dosimetry

The changes in the optical absorption spectra of unplasticized poly(vinyl chloride), UPVC films, irradiated with high-energy proton beam in the range 25-37 MeV and at a fluence 2.25 x 10(9) ions cm(-2) have been studied. However, at the beam energy 25 MeV and with increasing the beam fluence up to 10(15) cm(-2), the experiment was performed again upon another series of films, where the films became darken. The dependence of the optical absorption on the beam fluence has been investigated in the fluence range of 10(11)-10(15) ions cm(-2), The changes in the band structure of the irradiated films were also measured spectrophotometrically using UV/VIS spectrophotometer. The results show that the tail width of the localized states in the band gap was decreased as the beam fluence increased which led to a decrease in the optical energy gap of the irradiated UPVC films. ESR and FTIR measurements for the samples were also undertaken. The results suggest the possible use of UPVC film as a dosimeter for H+ ion beam in the fluence range of this study (10(11)-10(15) ions cm(-2)) by means of visible spectrophotometry and ESR techniques. (C) 2002 Elsevier Science B.V. All rights reserved.