Materials Science & Processing Springer-Verlag 1998

Abstract.We have obtained atomically resolved STM images of individual single-wall carbon nanotubes. The interpretation of the apparent lattice is nontrivial. In most cases we observe a triangular arrangement instead of the expected hexagonal carbon lattice. However, the chirality of the nanotubes can be unambiguously determined from the images, which is an im-portant result because the electronic properties are predicted to be strongly dependent on the atomic structure. Since the discovery of carbon nanotubes [1, 2] much atten-tion has been directed to the electronic properties of these fullerene molecules. A remarkable result of theoretical calcu-lations [2, 3] is the strong dependence of the electronic band-structure of a nanotube on its chiral structure and diameter. Nanotubes can be either metallic or semiconducting, with en-ergy gaps that depend on the tube diameter. The prediction