October 24, 2005 – Researchers at South Korea’s Pohang U. of Science and Technology have developed what they call the world’s first subnanometer carbon nanotube with a diameter of 0.4nm, beating conventional limits of 1nm nanotubes by a process of reduction rather than creation.

The team used the tip of an atomic-force microscope to strip away layers of a multiwalled nanotube, “like peeling onions,” to get down to the innermost layer — leaving just a single-walled nanotube, according to Prof. Kim Kwang-soo, quoted by the Korea Times. “Technologically, it is not difficult at all,” he added.

The researchers also confirmed that the subnanometer nanotubes are metallic, rather than semicondutive, and said they have stretched the nanotube to a length of 1mm, about 1000x longer than previous lengths of 1 micron.