Optical properties of γ-irradiated Bombyx mori silk fibroin films

In the present work the Bombyx mori silk fibroin (SF) films were prepared by the solution casting method and effects of gamma-irradiation on the optical properties and optical constants of the films have been studied by using Ultra Violet-Visible (UV-Vis) spectrophotometer. The recorded UV-Vis absorption and transmission spectra have been used to determine the optical band gap (E-g), refractive index (n), extinction coefficient (k), optical conductivity (sigma(opt)) and dielectric constants (epsilon*) of virgin and gamma-irradiated films. Reduction in optical band gap and increase in refractive index with increasing radiation dosage were observed. It is also found that there is an increase in dielectric constants with increasing photon energy. The obtained results reveal that the refractive index of the SF films may be efficiently changed by gamma-irradiation.