A team of scientists from the Georgia Institute of Technology has observed ballistic conductance--a phenomenon in which electrons pass through a conductor without heating it--at room temperature in multi-walled carbon nanotubes up to five microns long. Structures of that size operating under those conditions could one day be useful for fabricating ever-smaller electronic devices. "This is the first time that ballistic conductance has been seen at any temperature in a three-dimensional system of this scale," reports Walt de Heer, a professor at Georgia Tech's School of Physics. In their lab, de Heer and collaborators attached a tiny electrode to a bundle of nanotubes that had a single long tube protruding from one end. They mounted the bundle in place of the probe normally used in an atomic force microscope and connected a battery to the electrode. They then used the microscope controls to raise and lower the single protruding nanotube into and out of a pool of mercury that served to complete the circuit back to the battery. The resistance they measured as the nanotube was raised and lowered into the mercury remained constant, changing only when a shorter tube protruding from the bundle--which resembles a handful of straw--made contact with the liquid metal. E-mail email@example.com.
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