Optical properties of polyvinyl alcohol film irradiated with Nd:YAG laser

Casting solution method has been used to prepare Polyvinyl alcohol (PVA) film. The prepared film has been irradiated with a laser beam of 6 ns Q-switched Nd:YAG laser (Lotus II) operating at 10 Hz and fourth harmonic wavelength, 266 nm, at different irradiation times. Optical absorbance of the irradiated sample was studied in the wavelength region between 200 and 800 nm. The absorption peak shift of 272 nm towards the longer wavelengths region and the increase of absorption as the irradiation time increases, are related to the increase in crosslinldng network. The fitting technique of the absorbance revealed an indirect allowed transition with optical energy gap of 422 eV for the pristine PVA sample, and 2.85 eV after 2 h of laser irradiation. The index of refraction and the dielectric function showed dispersion in the studied wavelength range. The analysis of color parameters of PVA showed an observable change after laser irradiation. (C) 2017 Elsevier B.V. All rights reserved.