Thermally induced plasmonic resonance of Cu nanoparticles in fullerene C70 matrix

Abstract

Nanocomposite of fullerene C70 embedded with Cu nanoparticles is synthesized using thermal co-deposition method. The temperature dependency of SPR and size of Cu nanoparticles are assessed by thermal annealing in inert atmosphere up to a temperature of 350 °C. Rutherford backscattering spectroscopy is performed to assess the thickness of the film and the atomic fraction of Cu metal. The UV-visible absorption spectra on as-deposited and annealed samples reveal that the SPR peak of Cu nanoparticles appears at 300 °C and its evolution with further rise in temperature takes place with a red shift and broadening of the peak at 350 °C. The thermal induced growth of Cu nanoparticles at higher temperature is responsible for the red shift. Raman spectra show the decrease in the intensity of vibrational modes of fullerene C70 with temperature due to breaking of bonds among carbon atoms in fullerene molecules. Transmission electron microscopy confirms the evolution of Cu nanoparticles with bi-modal distribution at 350 °C. Atomic force microscopy is performed to observe the variation in the morphology and roughness of nanocomposite film with temperature. The evolution of Cu nanoparticles and excitation of SPR with temperature makes it an interesting nanocomposite for SPR sensing applications.