After Sumio Iijima's successful 1991 microscoping of multiwalled carbon nanotubes that revealed these microscopic graphite needles to the larger scientific community, Iijima and his colleague Toshinari Ichihashi turned to the idea of creating and observing single-walled carbon nanotubes. Iijima believed that only the observation of single-walled nanotubes would yield full scientific knowledge of the exact characteristics of these tiny structures with a diameter of just about one-billionth of a meter and a length of up to one thousand times their diameter.

The idea of the existence and possible artificial growth of these ultrasmall particles was mentioned first in a U.S. patent of 1889, but there were no technical means in existence then to prove this. Optical microscopes could never go as far into microscopic detail as was necessary to observe these nanostructures. Only with the invention of the transmission electron microscope in 1939 were scientists able to look into the nanoscale realm with gradually increasing power of observation. Unbeknownst in the West during the Cold War, in 1952 two Soviet physicists, L. V. Radushkevich and V. M. Lukyanovich, published micrograph images that they had taken of carbon filaments. In 2006, when these old photos were examined again, it became clear that they actually showed multiwalled carbon nanotubes, making Radushkevich and Lukyanovich the first to discover them. Still, it was Iijima's 1991 observation of multiwalled carbon nanotubes that triggered the great interest in these structures. Moreover, the quest was still open for the discovery ofa single-walled carbon nanotube.

To this end, Iijima and Ichihashi decided on a new approach to grow carbon nanotubes, which so far had been observed only in their multiwalled state. In 1993, Iijima set up an experiment at his Fundamental Research Laboratories of the NEC Corporation in Tsukuba, Japan. In an evaporation chamber in their laboratory, two electrodes were set up in a vertical position close to each other. The anode consisted of a graphitic carbon rod with a diameter of 10 millimeters, while the graphitic carbon rod of the cathode had a diameter of 20 millimeters and held a small piece of iron in a hollow at its tip, acting as catalyst. The evaporation chamber was filled with a gas mixture of methane (a source of more carbon) and argon. Next, Iijima and Ichihashi applied a direct current of 200 amperes and 20 volts to run between the two electrodes, creating a carbon discharge arc that vaporized the iron and the carbon, which formed soot together with the methane. The resulting soot that collected over the electrodes was put into an acetone suspension and placedunder Iijima's microscopes.

Looking at the carbon soot with both a regular and an ultrahigh-vacuum transmission electron microscope, Iijima took the image of the single-walled carbon nanotubes that the experiment had generated. The discovery of these nanotubes, with diameters from 0.7 to 1.6 nanometers each, triggered further advances in the research of their exact mechanic and electric properties. Iijima and Ichihashi had discovered the basis on which the new field of nanotechnology came to be built.

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