Researchers at Brown University and in Korea have developed a method of cutting single-walled carbon nanotubes of any diameter at any rate. This finding would lead to producing more precise, higher-quality nanotubes and make the nanotubes more attractive for use in automotive, biomedicine, electronics, energy, optics and many other fields.

The basics of carbon nanotube manufacturing are known. Single-atom thin graphene sheets are immersed in solution (usually water) and the jumbled bundle of nanotubes are then blasted by high-intensity sound waves to create cavities (or partial vacuums) in the solution. The bubbles that are compresses at an acceleration 100 billion times gravity arise from these cavities expand and collapse so violently that the heat in each bubble's core can reach more than 5,000 deg,K. The tubes which come out at random lengths are sieved to get tubes of the desired length. The technique is inexact partly because no one was sure what caused the tubes to fracture.

Materials scientists initially postulated that the fracture may have happened due to super-hot temperatures causing the nanotubes to tear or the sonic boom lets caused by collapsing bubbles pulled the tubes apart.

But the researchers found that the tubes were compressed mightily from both ends and caused a buckling in a roughly five-nanometer section along the tubes called the compression-concentration zone. In that zone, the tube is twisted into alternating 90-degree-angle folds, so that it fairly resembles a helix. It was further learned the mighty force exerted by the bubbles' sonic booms caused atoms to be shot off the tube's lattice.

The researchers also found that cutting single-walled carbon nanotubes using sound waves in water created multiple kinks, or bent areas, along the tubes' length making them highly attractive intramolecular junctions for building molecular-scale electronics.