Abstract
CR-39 polymer samples were irradiated with gamma-irradiation up to dose ranging from 500 to 2000 kGy. The virgin and gamma-irradiated polymer samples were investigated using UV-visible spectroscopy and Fourier transform infrared (FTIR) spectroscopy. In the present work, the Urbach energy was calculated using the Urbach edge method. Also, the direct and indirect energy band gaps in virgin and gamma-irradiated CR-39 polymer samples were calculated. The values of indirect energy band gap were found to be lower than the corresponding values of direct energy band gap. The decrease in the optical energy band gap with increasing gamma-irradiation dose was discussed on the basis of gamma-irradiation-induced modifications in CR-39 polymer. The correlation between optical energy band gap and the number of carbon atoms in a cluster with modified Tauc's equation was also discussed. The FTIR spectra show considerable changes due to gamma-irradiation, indicating that the detector is not chemically stable.