Nickel nanoparticle catalysed formation of fullerene like carbon nanostructures - a Raman analysis

The catalytic effect of nickel nanoparticles on the formation and on the structure of fullerene-like carbon nanostructures prepared by ion beam sputtering at different temperatures was studied by wavelength dependent Raman spectroscopy. Compared to nickel-free reference films the formation of carbon nanostructures is enhanced in the whole range of deposition temperatures from 25°C =< T (°C) <= 500°C. Several phases characterized by different ratios of amorphous and graphite-like carbon, a different film transparency, and a different elastic Raman background intensity, were observed. Amorphous carbon structures are preferentially formed at lower deposition temperatures, whereas graphitic structures are dominant for higher growth temperatures. Based on data for different excitation wavelengths and using difference spectroscopy, a quantitative model for the composition of these nanostructured carbon materials is developed. The results are in full agreement with those obtained by TEM, XANES and XRD analysis.[1] The model might be used as well for the analysis of other pure carbon or carbon based composite materials like CN and BCN films.
[1] G. Abrasonis, A. Mücklich, K. Küpper, M. Krause, U. Kreissig, A. Kolitsch, W. Möller, K. Sedlackova, G. Radnoczi, R. Torres, and I. Jimenez, "Morphology and bonding structure of fullerene-like nanocomposite C:Ni (~30 at%.) thin films grown by ion beam sputtering", to be presented on XXI. IWEPNM, Kirchberg, 2007