Carbon nanotubes are hexagonally shaped arrangements of carbon atoms that have been rolled into tubes. These tiny straw-like cylinders of pure carbon have useful electrical properties. They have already been used to make tiny transistors and one-dimensional copper wire.
They were developed by using nanotechnology, a relatively new field that involves building electronic circuits and devices from single atoms and molecules. Nano means one thousand millionth of a unit. A nanometer is therefore one thousand millionth of a meter. The first nanofabrication experiments occurred in 1990 when individual xenon atoms were placed on a nickel substrate and used to spell out a company logo. One primary goal of nanotechnology is to build computer chips and other devices that are thousands of times smaller than they are now.
Carbon nanotubes have enormous theoretical possibilities but have not lived up to the hype surrounding their development. Researchers have continued to look for ways to use them, however, as successful applications have the potential to be highly lucrative. Additionally, scientists have recently succeeded in altering carbon nanotubes so that they supply electrons when exposed to light. This was done by having two flat rings of carbon molecules sandwich a ferrocene (iron) molecule. Ferrocene is known for its tendency to relinquish electrons. When exposed to visible light, the carbon atoms accepted the ferrocene molecule.
This is the first time that carbon nanotubes have been hybridized to undergo light-induced electron transfer. Researchers say that these modified nanotubes are the first step in building solar cells using this technology.
The newly-discovered ability of carbon nanotubes to serve as electron sources has great potential. These atoms may one day replace the metal filaments in X-ray machines, which tend to burn out quickly. Scientists hope to use them to develop portable X-ray machines for use in airport security, ambulances, and customs work.
Carbon nanotubes also have great significance for use in flat-panel displays, microwave generators, devices for electric surge protection, and high intensity lamps.