Recent measurement of the momentum-dependent electron energy loss spectra (
EELS) of single-wall carbon nanotubes revealed several low energy peaks in
addition to the pi plasmon pi + sigma plasmon peaks in the ranges of 5-7 eV
and 21-24 eV, respectively. In the present Letter it is shown that the low
energy peaks can be attributed to the plasmons associated with the collect
ive azimuthal motion of the electrons on the surface of the nanotubes. (C)
2001 Elsevier Science B.V. All rights reserved.