Carbon nanotubes ignite when exposed to flash

Researchers at Rensselaer have discovered a new property of single-walled carbon nanotubes (SWCN) that, when exposed to a conventional photographic flash, emit a loud pop and then ignite.

This discovery could mean that SWCNs might be used in light sensors or to remotely trigger explosives and combustion reactions, although researchers say that more testing needs to be done to realise these possibilities.

The loud popping sound heard after the flash is actually a well-known phenomenon called the photo-acoustic effect. This phenomenon, not previously associated with carbon nanotubes, occurs when porous black objects absorb a large amount of light, which results in the expansion and contraction of the gas surrounding them, releasing sound.

What surprised the researchers even more was the fact that the nanotubes then spontaneously ignited and burned upon photographic flash exposure.

The discovery was initially noted when flash photographs of the nanotubes were taken.

Since the discovery, the researchers have conducted a variety of experiments to test how light exposure affects the nanotubes. They found that while the tubes burn only when oxygen is present, their atomic structure is altered even in inert gas environments when exposed to the flash. The exciting thing is the fact that the nanotubes are transformed into new carbon structures in the absence of oxygen.

From an applications perspective, the work opens up possibilities of using low-power light sources to create new forms of nanomaterials, and will serve as a starting point for developing nanotube-based actuators and sensors that rely on remote activation and triggering.

For further information please contact Pulickel Ajayan or G. Ramanath at the Rensselaer Polytechnic Institute.