Gamma irradiation effect on the optical properties and refractive index dispersion of dye doped polystyrene films

Abstract

In this work, we have studied the effect of the gamma irradiation on the optical properties and optical constants of Polystyrene doped by methylene blue (mb) with thickness in the range 0.11 + 5 mm. The samples have been investigated via transmittance and reflectance spectra, and characterized in the wavelength range 300-900 nm. The optical band gap E_g was determined while the optical absorption spectra showed that the absorption mechanism is an indirect allowed transition, which found that optical energy gap E_g decreases after irradiation. The optical constants (refractive index, extinction coefficient, and real and imaginary parts of the dielectric constant) showed clear changes with irradiation. The oscillator energy E_o, dispersion energy E_d and other parameters have been determined by the Wemple-DiDomenico method. The most significant result of the present study is to determine the optical constants and optical band gap of the film.