By Ashley Yeager
Nanotubes are tiny, and they can give off light. Those properties make the carbon constructions promising for looking at cells inside our bodies and also making small electrons that can capture and manipulate light.
But recent research suggests that not all nanotubes shine as chemists thought, a discovery that ends a debate in the field about which type of tubes to use for applications relying on their ability to emitted light.
The debate pitted single-walled carbon nanotubes against double-walled ones. Some scientists thought only single-walled tubes could give off light and be used in light-related applications. But other scientists showed that double-walled nanotubes could also emit light and possibly replace their single-walled cousins.
Now, Sungwoo Yang, a former chemistry graduate student at Duke, and his colleagues in Jie Liu’s lab have shown that both single and double-walled carbon nanotubes shine when hit with lasers. But, in the double-walled tubes, only the inner wall emits light and only a small range of diameters of the inner tube could get their light to the outside world. The ones outside of this range gave off light, but it got doused on its way through the outer layer.
Bottom line: Some double-walled carbon nanotubes do emit light but most don’t, if you’re looking for the light outside of the tube. That discovery makes both camps in the nanotube debate correct, depending on the diameter of tube being considered.
CITATION: “Photoluminescence from Inner Walls in Double-Walled Carbon Nanotubes: Some Do, Some Do Not.” Sungwoo Yang, Ashley Parks, Stacey Saba, P. Lee Ferguson, and Jie Liu. Nano Lett., 2011, 11:10, 4405–4410