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.