Proton Beam Induced Modification of Luminescence Properties of Polystyrene/Al2O3 Polymer Nanocomposites.

Polystyrene polymer (PS)/Al2O3 nanocomposite films were synthesized from PS:Al2O3 (1-x):x mixtures (x = 3 wt%) via solution casting method. These nanocomposite films were exposed to 5 MeV proton beam of different fluences. The proton beam induced changes in optical and luminescence properties of PS and PS:Al2O3 films have been investigated using FTIR, UV-visible, Photoluminescence and thermoluminescence studies. FTIR studies concede reduction in the peak intensity due to doping of Al2O3 and proton irradiation. The UV-visible spectra show shifting of absorption edge with increasing fluence. This can be attributed to creation of conjugated system of bonds. The band gap of PS and 3 wt% Al2O3 doped PS is observed to be 4.38 eV and 4.34 eV, respectively, whereas the band gaps of proton irradiated 3 wt% Al2O3 doped PS films are found to be 4.28 eV and 4.23 eV at the fluences of 1 × 1012 ions/cm2 and 1 × 1013 ions/cm2, respectively. The photoluminescence emission spectra show three peaks, wavelength at 411 nm, 435 nm and 462 nm corresponding to the PS in violet-blue region when excited with near UV wavelength of 380 nm. The intensity of emission peaks was found to increase with increasing fluence. The thermoluminescence curves of PS/Al2O3 were analysed using glow curve deconvolution method (GCD). The increase in TL peak intensity of the glow curve was observed as fluence increase.