NANOSCALE ABACUS. Scientists at IBM Zurich have used a
scanning tunneling microscope (STM) probe to reposition C-60
molecules on a copper substrate, making in effect the first room-
temperature device capable of storing and manipulating numbers
at the single molecule level. The buckyballs (which are big,
sturdy molecules) act as the counters of a tiny abacus in which
low (indeed mono-atomic) terraces in the copper surface
constrain the buckyballs to move accurately in a straight line.
(The abacus is perhaps the first human calculating device, and the
Greek word means "sand on a board.") IBM researcher James
Gimzewski (gim@zurich.ibm.com) admits that his device is
slow: "The tool we use (the STM probe) is the equivalent of
operating a normal abacus with the Eiffel Tower." But things
should improve in coming years; with this new advance,
hundreds of buckyball ranks could fit neatly inside the same
linewidth that characterizes features on a Pentium processor chip.
As for speed, engineers expect to fabricate arrays of hundreds
and even thousands of STM probes for simultaneously imaging
(and repositioning) many atoms and molecules. (M.T. Cuberes
et al., to appear in the 11 November issue of Applied Physics
Letters; an associated figure can be obtained on the Web at
http://www.aip.org/physnews/graphics)