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A bi-functional nanocomposite thin film containing Ag nanoparticles embedded in fullerene C 70 is synthesized by thermal co-evaporation technique. Tuning of plasmonic resonance of Ag-C 70 nanocomposite is obtained by annealing the nanocomposite thin film at different temperatures from 80 to 300 °C for 30 min. The optical and structural properties of nanocomposite thin film with respect to high temperature are studied by UV–visible absorption spectroscopy and X-ray diffraction. Transmission electron microscopy is performed to investigate the temperature dependent size evolution of Ag nanoparticles in fullerene C 70 matrix. Growth of Ag nanoparticles is observed with increasing temperature above 200 °C due to enhanced diffusion of Ag in fullerene C 70 and Ostwald ripening. The optical and structural properties of metal-fullerene nanocomposite is not significantly affected upto a temperature of 150 °C, after that a progressive blue shift of ~ 27 nm in SPR wavelength is observed with increasing temperature. The tuning of SPR is ascribed to the thermal induced structural transformation of fullerene C 70 matrix into amorphous carbon and also to mutual polarization of the particles.

We study the optical and microstructural properties of silver/amorphous carbon (Ag/a-C) nanocomposite thin film and its modification induced by swift heavy ion irradiation. Ag nanoparticles (NPs) embedded in a-C matrix were synthesized by co-sputtering of Ag and graphite by 1.5 keV neutral Ar atom beam. These Ag NPs were irradiated by 120 MeV Ag ions at different fluences ranging from 1 × 10 12 to 3 × 10 13 ions/cm 2 . Optical absorption studies revealed that surface plasmon resonance of Ag NPs in pristine film occurs at a wavelength of ~ 430 nm and it shows a blue shift (~ 26 nm) with increasing ion fluence up to 3 × 10 13 ions/cm 2 . Transmission electron microscopy and Rutherford backscattering spectroscopy were used to quantify particle size and metal atomic fraction, respectively, in the nanocomposite films. The growth of Ag NPs with bi-model distribution at a fluence of 3 × 10 13 ions/cm 2 was observed with ion irradiation. Raman spectroscopy was used to investigate the effect of heavy ion irradiation on carbon matrix. The blue shift in plasmonic wavelength is explained in terms of increase in sp 2 content in carbon matrix by heavy ion irradiation due to thermal energy deposition which leads to a decrease in dielectric properties of the matrix.

The effects of ion irradiation on electrical and magnetic properties of C60 films are investigated and correlated to changes of structure. Conducting nanowires are formed along the linear path of swift heavy ions. Their continuity and radial dimension are correlated with the energy density deposited by such ions in electronic excitations. Whatever the slowing down process of ions, irradiation at high ion fluences induces the formation of an amorphous C phase exhibiting a ferromagnetic response up to room temperature. An additional paramagnetic signal is recorded from films irradiated with swift ions, which is ascribed to the formation of oriented defects decorated with oxygen.

International audience; In the present study, we have investigated the swift heavy ion induced structural modification of ZnO thin film deposited by atom beam sputtering. The films were irradiated by 100 MeV Ag ions at different fluences from 5 x 10(10) ions/cm(2) to 3 x 10(13) ions/cm(2). The influence of the irradiation fluence on structural and optical properties of these thin films was investigated. The structural properties have been studied using X-ray diffraction. The Zn-O bonding was confirmed by Fourier transform infrared spectroscopy and surface morphology was investigated by atomic force microscopy. XRD confirmed that the grain size and texture of the ZnO thin film are increased after the irradiation. The absorption peak intensity corresponding to Zn-O bonding is also increased as a result of energy deposition by swift heavy ion as revealed by FTIR. The AFM study of the films implied that roughness remains almost constant. Power spectral density was also estimated from the AFM micrograph to extract the value of roughness exponent. (C) 2009 Elsevier B.V. All rights reserved.