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IGNITING NANOTUBES
Carbon Nanotubes Ignite
Researchers Pulickel Ajayan and G. Ramanath have
discovered a surprising new property of single-walled carbon nanotubes.
When exposed to a conventional photographic flash, the nanotubes
emit a loud pop and then ignite.
 The
discovery, reported in the April 26 issue of the journal Science,
could mean that the nanotubes might be used in light sensors or
to remotely trigger explosives and combustion reactions. Researchers
say that more testing needs to be done to realize these possibilities.
The researchers say that the loud popping sound
heard after the flash is a well-known phenomenon, called the photo-acoustic
effect. It occurs when porous black objects, such as carbon nanotubes,
absorb a large amount of light, which results in the expansion
and contraction of the gas surrounding them, releasing sound.
“From an applications perspective,
our work opens up exciting possibilities of using low-power
light sources to create new forms of nanomaterials. The discovery
will serve as a starting point for developing nanotube-based
actuators and sensors that rely on remote activation and triggering”
—G. Ramanath—
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What surprised the researchers was that the nanotubes
then spontaneously ignited.
Graduate student Andres de la Guardia made the
initial discovery when he took flash photographs of the nanotubes.
Since the discovery, the researchers have found
that, while the tubes burned only whenoxygen is present, their
atomic structure was altered even in inert gas environments.
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