One of the latest additions to the expanding menagerie of carbon nanostructures is the single walled carbon nanotube (SWNT) that encapsulates a string of spherical C60 molecules. Each C60 is only 0.7 nm in diameter and appears as a circle in the high resolution micrograph shown above.

This nanoscopic peapod was announced by its discoverers, Brian Smith (Penn), David Luzzi (Penn) and Marc Monthioux (CEMES, France), in Nature [396, 323 (1998)]. Utilizing the high resolution imaging and in-situ capabilities of the TEMs in the facility, the encapsulated buckyballs are seen to move back and forth inside the nanotubes, lining up in groups of two, three, or more -- just like arrangements of beads on an abacus.

This finding opens a new field in nanotube research and could conceivably affect the interpretation of earlier results, which were obtained with the supposition that the tubes are empty. "Very, very cool -- just mind-blowing" commented fullerene researcher Daniel Colbert (Rice). "I think they probably will end up teaching us something about the nucleation and growth of nanotubes."

excerpted in part from Chemical & Engineering News 77 (2), 32 (1999)