60 MeV Ni ion induced modifications in nano-CdS/polystyrene composite films

• Synthesis and irradiation of metal doped nano-composites with swift heavy ions (SHI) at different fluences.
• Structural, optical and chemical changes after irradiation were examined by XRD, UV–visible and FTIR spectroscopy respectively.
• Change in crystalline nature and decrease in band gap are observed with increase in fluence.
• The modifications caused by SHI in various chemical bonds are also discussed.

The cadmium sulfide (CdS) nanoparticles of size in the range 50–60 nm were synthesized by micro-emulsion method. The polystyrene/CdS (PS/CdS) nanocomposites were doped with Ni and Cu metals. The pristine and doped samples were irradiated with 60 MeV Ni ions. The effect of doping of metals and ion irradiation was studied for modifications in structural, optical and chemical properties of PS/CdS nanocomposites. The decrease in peak width of XRD spectra of irradiated PS indicated the decrease in the amorphous nature at higher fluences. The optical absorption peaks of the irradiated and doped samples shifted towards visible region. The shift in case of metal doped samples was more pronounced than those of pure polystyrene and PS/CdS matrix samples. The increase in absorption was attributed to the generation of a conjugated system of bonds. The decrease in band gap energy value in case of Ni doped PS/CdS was greater than that of Cu doped PS/CdS and the ion irradiation further decreased the band gap energy value. The vibrational absorption peak of the Cd–S bond was observed at 405 cm−1 in FTIR spectra of metal doped PS/CdS composites. The intensity of styrene absorption lines decreased in all irradiated samples.