The Amazing Bend-o-Nanotubes

Auxon writes "Dr.Dobb's reported today a new discovery in the nature of carbon nanotubes that may be a key contribution to the realization of nanotechnological dreams. The article describes the accidental findings by "Hongjie Dai, Stanford assistant professor of chemistry, and graduate student Thomas Tobler in collaboration with University of Kentucky theoretical physicists," who used an Atomic Force Microscope (AFM) to bend a tiny nanotube. As the tube bends, the electrical conductivity decreases; something predicted NOT to happen in previous theoretical work. "As one side of the tube is pushed closer to the other, carbon atoms form bonds across the inside of the tube. Normally, each carbon atom binds to three other carbons, leaving one electron free for use in conducting electricity. But when the walls of the tube come close together, each carbon binds to four rather than three carbons. The resulting decrease in the number of free electrons causes the electrical conductance to slow. "The AFM tip squashes the tube, causing each atom to bond with more atoms," said Dai. "This causes the tube to turn from an electrical conductor into an insulating structure similar to that found in diamonds." Remarkably, the dent disappears once the perturbing tip is removed. This high mechanical reversibility allows the full recovery of the nanotube's electrical property, Dai said.""