or nanoscience, refers to the study of objects in
the size range of nanometers. A nanometer is about
10 times the size of a hydrogen atom. For example,
if you were to line up objects at this scale, you
would be able to fit over a billion of them in one
inch, says Tysoe. This offers the possibility, for
example, of placing trillions of miniscule devices
on the area of a dime.
But at this small scale, conditions can be very
different from those of the classical physical environment.
It makes sense, says Tysoe, because a single atom
will behave differently from a bulk piece of material
containing trillions and trillions of atoms.
"There's a lot of talk about it, but relatively
little work focuses on the regime of the transition
between the classical physical world and the quantum
world. That's where the science comes in," says Bennett.
The diameter of a single E. coli bacterium is as
small as a wire can get before it stops acting classically,
In their collaborative project, Bennett designs
the molecules and Tysoe studies the nature of surface
interactions and their conductive properties. They
believe they have the right molecule and the right
metal surface. The next step will be connecting the
They also are measuring the electrical properties
of Bennett's molecules to see if their properties
are similar to those of large-scale wires.
It is a delicate process. With forces much less
than those exerted by the foot of an ant, a small
gold tip is brought into contact with the surface,
a voltage is applied, and the current is measured
through an array of nanowires (see illustrations
"We are finding that, although the molecules do
conduct extremely well, the current that passes through
them is not directly proportional to the voltage
applied, the way it would be with bulk wires," says
Another potential application for this class of
molecules is as tunable catalysts.
A catalyst is a substance that can increase the
rate of a chemical reaction by lowering the energy
required to form a product. Catalysts are used in
a myriad of ways, such as to make useful products
from crude oil, minimize harmful emission from automobiles,
or produce fertilizers.
Their efficacy, however, generally depends on the
electronic structure of their components. Since the
metals in the nanowires molecule can be electrically
connected to a surface, this offers the possibility
of adjusting its electronic proper