Number 279 (Story #2), July 15, 1996 by Phillip F. Schewe and Ben Stein ELECTRICAL AND MECHANICAL PROPERTIES OF INDIVIDUAL CARBON NANOTUBES : Because of their nanometer diameters and micron lengths, nanotubes are difficult to study singly. A team of scientists at NEC (Princeton) and the University of Illinois has, nevertheless, measured the Young's Modulus (indicative of a material's elasticity) of an assortment of nanotubes by noting the amount by which the tips of the freestanding tubes are blurred in microscopic pictures taken at various temperatures. (Higher temperatures lead to more thermally induced vibration.) The researchers found that the fibers had an average modulus of 1.8 TA (1.8 x 10**12 N/m**2), higher than that of steel. This extreme stiffness, along with low density, might make carbon nanotubes an excellent ingredient in building materials. (M.M.J. Treacy et al., Nature, 20 June 1996.) Electrical properties are potentially no less important. Another NEC experiment, this time in conjunction with Micrion Europe (Munich, Germany) and Fundamental Research Laboratories (Tsukuba, Japan), has succeeded in connecting four tungsten probes to individual nanotubes. This affords a more controlled study of conductivity than was possible in previous two-probe experiments. The four-probe tests have yielded nanotubes with a wide range of properties, from metallic to semiconducting. The researchers conclude that a tube's conductivity depends greatly on its diameter and on the helicity of carbon atoms making up the layers of the tubes. (T.W. Ebbesen et al., Nature, 4 July 1996.)