Creating the narrowest carbon nanotubes.

The properties of carbon nanotubes1 depend on their diameter and on the two integers (m,n) that describe their roll-up vector2. The smallest nanotube reported previously had a diameter of 0.7 nm, the same as that of a C60 structure3, although nanotubes with a diameter of 0.4 nm have been predicted4. Here we report that simple improvements in the electric-arc technique can create a carbon nanotube with a diameter of 0.5 nm — the same as a C36 molecule5.