Gamma irradiation induced chemical and structural modifications in PM-355 polymeric nuclear track detector film

Abstract

This experimental study investigated the modification of chemical and structural properties of PM-355 films by irradiation of 1.25MeV 60Co γ-radiations at doses ranging from 0–675kGy. The induced modifications were followed by micro-Raman and X-ray diffraction (XRD) spectroscopy. Further, the induced modifications were confirmed by UV–Visible spectroscopy. Raman spectra show that the films are highly disordered at the highest gamma dose. The XRD pattern of PM-355 shows the decreasing intensity of peak positions with an increase in the gamma dose, which suggests the loss of crystallinity of the films due to irradiation. Observed results indicate the formation of a disordered system in the irradiated films. Furthermore, the crystallite size for pristine and bombarded sample has been calculated. Moreover, interchain distance, micro strain, interplanar distance, dislocation density and distortion parameters were calculated. The analysis revealed a significant increase in micro strain, dislocation density and distortion parameters with an increase of gamma dose, which is in line with the Raman analysis. With increasing γ-dose, the value of the direct and indirect band gap found to decrease. To the best of our knowledge, this work is the first to show the simultaneous existence of direct as well as the indirect band gap in PM-355 polymer.