Carbon nanotubes beam electrons

The scientists who work with carbon nanotubes have big dreams for the tiny objects, including superfast electronics and hard spaceship materials. To date, however, few applications using the nanoscale carbon cylinders have been realized.

Now, a team from the Netherlands and France has taken a step toward making carbon nanotubes the electron sources for machines such as high-resolution electron microscopes.

Beams of electrons in microscopes are generally produced by heating or applying an electric field to a metal tip. The new work, reported in the Nov. 28, 2002 Nature, shows that carbon nanotubes could be superior electron sources.

In their experiments, the scientists mounted a single, 10-nanometer-wide carbon nanotube on the end of an electron microscope’s tungsten tip, applied an electric field, and studied the nanotube’s electron emission.

The electron beam was 10 times as bright as that from a conventional source, the researchers report. The nanotube also emitted a stable beam of electrons with uniform speeds, or energies, says team member Niels de Jonge of Philips Research Laboratories in Eindhoven, the Netherlands. Increasing a beam’s brightness and its uniformity in electron energies are two ways of improving the resolution of electron microscopes, he says.

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