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 degrees 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 C-60 molecule and the other to the C-240 molecule. The results suggest that carbon onions formed with our technique consist of concentric spheres of fullerenes C-n (n = 60, 240,...). (C) 1998 Published by Elsevier Science B.V.