The Atom Car

The vehicle is the latest in a series of experimental machines designed to operate on the nanometer scale8212;a nanometer being one billionth of a meter, or the distance spanned by about five hydrogen atoms. The creations reflect scientists8217; growing ability to build molecule-size devices that, by virtue of their tiny size and particular atomic configurations, can complete tasks not possible on larger scales.

Made by James M Tour and colleagues at Rice in Houston and described in the April 13 issue of the journal Organic Letters, the vehicle has four 8216;8216;wheels8217;8217; that are cagelike structures of about 25 atoms each, mounted on 8216;8216;axles8217;8217; that are freely rotating chemical bonds. The car is powered by a paddle-wheel-like device that turns in response to a specific wavelength of light. So far it has been shown to work in liquid8212;an environment that makes it easier to see molecular-scale events.

The team is now designing an optical system that will allow it to see the car motoring along on a dry surface. Nanocars may someday lug molecular cargo to microscopic construction sites8212;delivering atomic components into labyrinthine nanoelectronic circuits, for example8212;or they may drive around like a plow, gouging channels into nanoscale computer chips. Tour said he has six new models coming out in 2006. And since a trillion trillion of them are made at a time in a series of chemical reactions, he added, they should be cheap enough to discard after one trip each. Rick Weiss