Electron energy-loss spectra of single-shell carbon nanotubes

Transmission electron energy-loss spectra of single-shell carbon nanotubes were measured and compared with those of multishell carbon nanotubes and graphite. Two peaks due to the 7r plasmon and the π + σ plasmon were observed at 5.8 eV and 20.6 eV, respectively. The energy of the 7r plasmon takes a value between those of two kinds of multishell tubes. The energy of the π + σ plasmon is lower than those of multishell tubes and graphite by 2 eV and 6 eV, respectively. The 1s→ π* and 1s→ σ* transition peaks of the single-shell tubes are much broader than those of the multishell tubes and graphite. The reason for the broadening may be due to the strong curving of the graphitic sheets.