Changes in Optical Properties of Thermal-radiation-modified Polytetrafluoroethylene Exposed to Accelerated Xenon Ions

Abstract

The interaction characteristics of accelerated 3.2 MeV/nucleon xenon ions with 100-μm-thick thermal-radiation-modified polytetrafluoroethylene (TRM-PTFE) films were determined using computer simulation. It was found that the initially homogeneous TRM-PTFE sample was transformed during radiolysis into a layered structure including zones of intense and partial radiolysis and a layer of intact polymer. The spatial distribution characteristics of ionization losses and the absorbed dose field in the region of radiation damage around the latent track of a xenon ion were calculated. The optical properties of 100-μm-thick TRM-PTFE films exposed to 3.2 MeV/nucleon xenon ions up to a fluence of 1.08·10⁶ cm^–2 were studied. Optical spectra of TRM-PTFE exhibited absorption maxima at 206 and 476 (374, 578) nm, which may have been due to isolated double bonds and polyene structures containing 14 conjugated double bonds, respectively. Radiation-induced interference was detected and may have been due to the formation of a 0.34–0.39-μm-thick radiation-damaged layer that may have been located up to ~36 μm from the surface of the TRM-PTFE sample. It was concluded that the predicted estimates of radiation-induced changes in the optical properties of TRM-PTFE films and the experimental data were correlated.