120 keV Ar ion-induced red and blue shift of SPR Wavelength of Au nanoparticles in fullerene C60

Au nanoparticles are synthesized in a fullerene C-60 matrix using the thermal co-evaporation technique. Fullerene C-60 is chosen due to its high dielectric constant which gives a large tuning of SPR wavelength of Au nanoparticles in the visible region. A beam of 120 keV Ar ion is used to tune the SPR wavelength of Au nanoparticles in both the regions, lower wavelength (blue shift) and higher wavelength (red shift). The shift in SPR wavelength is found to be dependent on the dose of the beam. A similar to 161 nm red shift in SPR wavelength is obtained at a dose of 1 x 10(15) ions/cm(2), and then a blue shift of similar to 221 nm is obtained at a dose of 3 x 10(16) ions/cm(2). Growth in the size of Au nanoparticles is obtained with ion irradiation as confirmed by transmission electron microscopy on Au-C-60 nanocomposite thin film which is responsible for the red shift in SPR wavelength. Raman spectroscopic study confirms the transformation of fullerene C-60 matrix into amorphous carbon at higher doses, which gives a blue shift to SPR wavelength. The surface morphology of the Au-C-60 nanocomposite film before and after irradiation was studied using FESEM and AFM. A growth of surface grains is achieved with an increasing dose. The chemical state of the Au and Carbon in nanocomposite film before and after the ion irradiation is studied by X-ray photoelectron spectroscopy.

Automated summary

Au nanoparticles are synthesized in a fullerene C-60 matrix and their SPR wavelength is tunable by ion irradiation. The dose of the ion beam affects the shift of SPR wavelength and the growth of nanoparticles. Raman spectroscopy confirms the transformation of the fullerene C-60 matrix into amorphous carbon at higher doses, resulting in a blue shift of SPR wavelength.