Publications

2007

• Transformation of graphite into nanodiamond following extreme electronic excitations
  
  • Dunlop A.
  • Jaskierowicz G.
  • M. Ossi P.
  • Della Negra S.
  Physical Review B: Condensed Matter and Materials Physics (1998-2015), American Physical Society, 2007, 76, pp.155403. Graphite targets have been irradiated at 90 K and 300 K with 850 MeV and 6 GeV lead ions and with 20–30 MeV fullerene cluster ions in a large range of fluences. Damage creation was studied both by transmission electron microscopy and Raman spectroscopy. The very strong energy density deposited in electronic processes generates a highly excited region around the projectile path. The relaxation of the deposited energy via hydrodynamic expansion and shock-wave propagation leads to the formation of small defective graphitic domains and of nanocrystalline diamond particles. (10.1103/PhysRevB.76.155403)
  DOI : 10.1103/PhysRevB.76.155403
• Raman bands of double-wall carbon nanotubes : comparison with single- and triple-wall carbon nanotubes, and influence of annealing and electron irradiation
  
  • Puech Pascal
  • Flahaut Emmanuel
  • Bassil A.
  • Juffmann T.
  • Beuneu Francois
  • Bacsa Wolfgang
  Journal of Raman Spectroscopy, Wiley, 2007, 38, pp.714. We compare the G and G'2D bands of single-, double- and triple-wall carbon nanotubes (CNTs). We observe that the band shape is sensitive to the number of walls of the CNTs. For single-wall carbon nanotubes (SWCNTs), the G band is composed of two distinct contributions G+ and G−, while the G band for double-wall nanotubes is composed of one band with twomain contributions from the inner and the outer tube. The G'2D band can be fitted with one Lorentzian for single-wall tubes, while two distinct contributions are observed for double-wall carbon nanotubes (DWCNTs). Considerable variations of the G'2D band are found with similar first order Raman spectra. Annealing influences the D- and RBM-band intensities. Electron irradiation has the effect of decreasing the G- and D-band wavenumbers but does not enhance the D-band intensity considerably. The down-shifts of the G- and D-band wavenumbers are correlated and are the same for two excitation wavelengths. This is consistent with the scattering of phonons around the K-point.