Electronic band dispersion of vertically aligned multiwall-carbon nanotubes

We have investigated electronic band structure of the vertically aligned multiwall-carbon nanotubes using angle-resolved ultraviolet photoemission spectroscopy and density functional calculations. There exists a finite density of states at the Fermi level, a large one-dimensional subband dispersion, highly degenerate states, and a small momentum periodicity (with a lattice constant of 6.3 Å) in the band dispersion. This strongly suggests that the observed nanotubes are mostly metallic with a chirality of (4k,k), where k is an integer, as predicted from the density functional calculations, although the chirality of the multiwalled nanotubes are likely to be mixed.