Effect of gamma radiation on optical properties of PVA/PEG/EY blend, and radiochromism.

Abstract

Abstract PVA/PEG/EY samples were irradiated using of 50 KGy, gamma radiation dose. To investigate the effects of irradiation on the optical properties of the blend, UV-vis spectroscopy is used to study 6 samples of the blend, with different PEG content, 0, 1, 3, 5, 10, 15 percent, before and after irradiation. Radiation effects manifest itself as many changes in the following parameters: The absorption for all sample decreases after irradiation, the direct and indirect energy gap value increases after irradiation, the values of the extinction coefficient decrease after irradiation. The values of the extinction coefficient, k, of the nonirradiated samples are decreased or increased depending on the PEG content, while it increased for all irradiated samples despite of the PEG content. The refractive index, n, increases with increasing PEG concentration for irradiated and nonirradiated samples. The main changes occurred in the optical parameters after irradiation are: an increase in the values of the dispersion energy parameter, Ed, an increase in the single oscillator energy Eo, an immense decrease in the average oscillator strength, So, a large increase in the ratio of the effective number of carrier concentration to the effective mass of the electron (e2 /πc2). The values of the real and imaginary parts of the optical permittivity of irradiated samples are less than nonirradiated samples. The optical conductivity, σopt, increase for all irradiated samples. The values of O.D, are changing in four specific regions. The decrease and increase in O.D values depend on the variation in absorbance values which depend on PEG concentrations, and the role of irradiation in changing the absorbance of the blend.