Science and Education Publishing Physics and Materials Chemistry 2372-7101 3 2 2015 11 13 In-situ Synthesis of PVA/HgS Nanocomposite Films and Tuning Optical Properties 18 24 EN Omed Gh. Abdullah Department of Physics, Faculty of Science and Science Education, School of Science, University of Sulaimani, Kurdistan Region, Iraq Yahya A.K. Salman Salwan A. Saleem PMC2015321 10.12691/pmc-3-2-1 2015 7 14 2015 9 28 2015 11 11 Polymer based nanocomposite films of polyvinyl alcohol (PVA) doped with mercury sulfide (HgS) were prepared via in-situ chemical reduction and the solution cast methods, with different HgS concentrations, in order to study the effect of HgS content on optical properties of PVA. The nanocomposites films were characterized using FTIR, XRD, and SEM. The UV-Visible absorption spectra in the wavelength range (190-1100) nm were analyzed in terms of absorption formula for non-crystalline materials. The band gap and the fundamental optical constants of the prepared samples have been investigated and showed a clear dependence on the HgS concentration. The observed value of band gap for pure polyvinyl alcohol is about 6.27 eV and decreases to a value 4.88 eV for the film of 0.04M HgS content. The refractive index and consequently the related dispersion parameters of PVA and PVA/HgS nanocomposite versus HgS content have been determined and explained using Wemple-DiDomenico single oscillator model.