| RESEARCH |
Using Rayleigh to differentiate nanotubes Determining whether an individual single-walled carbon nanotube (SWNT) is semiconducting or metallic just got easier, thanks to researchers at Columbia University. A group led by Tony F. Heinz and Louis E. Brus has demonstrated that Rayleigh scattering spectroscopy can be used to identify the electronic transitions of both metallic and semiconducting nanotubes [Science, published online Oct. 28, http://dx.doi. org/10.1126/science.1103294]. The researchers report that this method is noninvasive and, unlike other SWNT-differentiating techniques, is general for nanoscale objects. Scientists had thought that Rayleigh scattering--a technique that uses elastic light scattering from small, polarizable objects to get spectroscopic information--would give only extremely weak signals when used to characterize nanoscale objects. However, Heinz and Brus's team found they were able to obtain Rayleigh scattering spectra with a high signal-to-noise ratio from individual carbon nanotubes when they used a white light source of laser brightness. The researchers hope to use the technique to probe other nanostructures. |
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