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The world's smallest abacus
 Zurich/Switzerland, November 13, 1996 -- Scientists at the IBM Research Division's
Zurich laboratory have built an abacus with individual molecules
as beads with a diameter of less than one nanometer, one millionth
of a millimeter. The world's smallest abacus will hardly be found
at a trade fair in the Far East, where calculators of this simple
kind are still used by dealers, because the "finger" required
to move beads as tiny as individual molecules is the ultrafine tip
of a scanning tunneling microscope (STM)—a needle of conical shape terminating in a single atom at the very
tip. The STM also makes the result of a "calculation"
visible when operated in imaging mode.
IBM scientists succeeded in forming stable rows of ten molecules
along steps just one atom high on a copper surface. These steps
act as "rails", similar to the earliest form of the abacus,
which had grooves instead of rods to keep the beads in line. Individual
molecules were then approached by the STM tip and pushed back and
forth in a precisely controlled way to count from 0 to 10 (see image
above).
"We have made significant progress in handling objects and
creating functional units on the nanometer scale at room temperature",
says James K. Gimzewski, leader of the nanoscience project at the
Zurich Research Laboratory. "Our work demonstrates a further
step in the new and fascinating field of 'nano-engineering', where
solid-state physics and chemistry merge. We may be able to assemble
more complex structures from the bottom up, as nature does, molecule
by molecule, and thus break ground for entirely new fabrication
technologies with a broad range of applications."
The beads used in the abacus experiment are the amazing soccer-ball-like
molecules formed by 60 carbon atoms (C60), the discoverers of which
were recently announced as the recipients of the 1996 Nobel Prize
in chemistry. These molecules are also known as buckminsterfullerenes
or "buckyballs" , named after the American architect Buckminster
Fuller, who invented the geodesic dome using the same pattern of
hexagons and pentagons.
The researchers who have long been studying the properties and
behavior of individual atoms and molecules and who have now realized
the nano-abacus are Maria Teresa Cuberes, James K. Gimzewski, and
Reto R. Schlittler at IBM's Zurich Research Laboratory. The effort
is part of the "PRONANO" (processing on the nanometer
scale) project sponsored by the Swiss Federal Office of Education
and Science within the European Strategic Program for Research in
Information Technology (ESPRIT) of the European Union.
The scientific report on the subject has been published in Applied
Physics Letters, Volume 69, Number 20 (p. 3016), November 11, 1996.
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