Investigation of transient species in pulse-irradiated poly(ethylene terephthalate) film

A pulse radiolysis study of poly(ethylene terephthalate), PET, film has been carried out with the main aims of investigating charge trapping. In PET, pulse radiolysis gives electron-positive hole pairs. Both charges can be stabilized by the reaction with polymeric matrix. In the first step, the PET radical anions and cations are formed (transient absorption maxima at similar to 370 and 530 nm). During the second step, the electron is transferred from a PET radical anion to an ester group, followed by formation of an ester radical anion (transient absorption maximum at 430 nm). The recombination of these ionic species leads to an excited state formation observed during and after the 1-mu s pulse. Spectral distribution of luminescence observed for pulse-irradiated PET (emission bands at similar to 340, similar to 370, and 400-410 nm) was similar to the one obtained for photoexcited PET. The detailed mechanism of ionic reactions in PET is proposed and discussed. (C) 1999 John Wiley & Sons, Inc.