Effect of gamma radiation on the optical and color properties of cellulose triacetate for the application in radiation dosimetry

One polymer that has been effectively used in the dosimetry field is cellulose triacetate (CTA). Cellulose CTA film samples were exposed to a range of gamma-ray doses, from 10 to 75 kGy. The resultant effects of the gamma ray irradiation on the optical and color properties of the produced CTA films were examined using UV-vis spectroscopy and the International Commission on Illumination (CIE) color alterations technique. The direct bandgap dropped from 5.25 to 3.91 eV when the gamma ray dose was increased to 75 kGy. The Urbach energy increased from 0.35 to 0.73 eV, indicating the predominance of chain crosslinks which destroyed the ordered structure and hence increased the amorphous regions. Additionally, the nature of the microelectronic transitions was detected with the help of the optical dielectric loss (epsilon"). Direct allowed transitions were discovered in the CTA films. The effects of the gamma-ray on the CTA films' light absorbance, extinction coefficient, refractive index, and optical conductivity were also examined. Additionally, the optical color differences between the irradiated and pristine films were identified. The non-irradiated CTA film had no color. When exposed to gamma ray doses up to 75 kGy, it displayed notable color changes (the red and yellow color components changed into green and blue, respectively).