Fourier transform infra-red characterization of carbon onions produced by carbon-ion implantation

Surface layers containing a high density of carbon onions were produced on silver substrates by high-dose carbon-ion implantation at 500°C. The morphology and microstructure were studied by atomic force microscopy and high-resolution transmission electron microscopy. Fourier transform infra-red experiments were performed to study the vibrational spectrum of these carbon onions and 9 absorption peaks were identified in the wavenumber range 400–1500 cm−1. Two families of vibrations were identified: one corresponding to the C60 molecule and the other to the C240 molecule. The results suggest that carbon onions formed with our technique consist of concentric spheres of fullerenes Cn (n=60, 240, …).