Page 78 - Carbon Nanotubes

STM of carbon nanotubes and nanocones 61

Fig. 1. Atomic resolution STM image of a 10 A nanotube of carbon with cross-sectional plot.

lar surface is a graphitic network. The honeycomb sur- at the substrate. In vapor-phase growth without a cat-
face net is arranged in a helical way, with a chiral angle alyst, the tubes may grow out of a hollow fullerene cap
of 5.0 f 0.5". instead of a compact spherical particle.
In a common method for the production of tubu- This view is supported by our observation of hemi-
lar carbon fibers, the growth is initiated by sub- spherically capped single-wall and multi-wall tubes on
micrometer size catalytic metal particles[ 191. Tube the same samples. It suggests that the C,,-derived
growth out of a graphite rod during arc-discharge tube could be the core of possible multilayer concen-
might also be related to nanoparticle-like seeds present tric graphitic tubes. After the single-shell tube has been

Fig. 2. Model of the Cm-based 10 A tube with zigzag configuration (C,,+,,j).