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 π plasmon and the π+σ plasmon were observed at 5.8 eV and 20.6 eV, respectively. The energy of the π 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.