In this article, Au nanoparticles in polyvinylpyrrolidone (PVP) solution were prepared by gamma radiation at different concentrations. The solutions were irradiated at doses of 50 kGy for making different sizes. The average sizes of particle in the prepared samples were measured using the nanophox machine. A dual-beam mode-mismatched thermal lens (TL) method was used to investigate the effect of thermal diffusivity of samples. The TL measurement was carried out using a green diode laser (wavelength 532 nm, 60 mW) and a He-Ne laser (wavelength 632.8 nm, 0.5 mW) for excitation source and probe beam, respectively. The results showed that the thermal diffusivity of samples enhances with the growth of particle size and density of solutions. This increment can be attributed to phonon scattering at interface of particlesliquid and contact between the nanoparticles and surrounded liquid.

Herein, a new polymeric nanocomposite of 2,5-diphenyloxazole (PPO) and polystyrene (PS) doped with cerium fluoride (CeF 3) nanoparticles (PS/PPO/CeF 3) was prepared, characterized and its photoluminescence property was reported for the first time. The PS as a base matrix and PPO as a fluor were chose for a scintillator solution substrate and CeF 3 nanoparticles dispersed into it to construct a new nanocomposite scintillator. The PS liquid polymeric matrix with 0.5 wt% of PPO was loaded with different percentage of CeF 3 nanoparticles. Structural characterizations showed successful preparation of nanocomposites and a mean size of CeF 3 nanoparticles as (13 ± 3) nm in the base polymer matrix. The measured photoluminescence showed an enhancement about 3 times in comparison to PS/PPO composite when 10% of CeF 3 nanoparticles doped into the polymeric composite matrix under UV excitation. This effect is due to fluorescence resonance energy transfer in Ce 3+ ions (5d → 4f transition energy) to the PPO within the PS/PPO/CeF 3 nanocomposite. Observed results were presented and discussed.

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