Down the tube

摘要

Super-sensitive single-atom detectors are the latest brainchild of researchers working with single-walled carbon nanotubes.rnAnne Goodsell and her co-workers at Harvard University in Cambridge, Massachusetts, harnessed one of the tubes' many unusual properties: their ability to create a powerful electric field when charged. The researchers suspended a 10-micrometre-long nanotube between two electrodes and charged it to hundreds of volts. They thenrnfired a beam of cold rubidium atoms at the tube. Atoms spiralled quickly around the tube until an electron jumped from a neutral atom to the positively charged tube. Once ionized, the atom was repelled by the tube, and shot out at high speed into a nearby detector.rnThe team believes that the technique could be useful as an atom 'sniffer' or counter.