Carbon nanotubes

Carbon nanotubes are a rich family of one-dimensional structures. They can be either semiconducting or metallic and their properties depend sensitively on the exact nanotube structure. To elucidate their different behaviors, studies of individual nanotubes are needed.

We have pioneered several single nanotube spectroscopy techniques for nanotube study. Shown in Fig. 1 are suspened carbon nanotubes (a) and Rayleigh scattering spectrum (b), absorption spectrum (c), and multiphonon Raman scattering spectrum(d) of individual single-walled nanotubes.

Fig. 1: Single-nanotube spectroscopy. (a) A suspended single-walled nanotubed. (b) Single-nantoube Rayleigh scattering spectrum. (Science 306, 1540, 2004), Science 312, 554, 2006). (c) Single-nanotube absorption spectrum (PRL 99, 227401, 2007). (d) Multiphonon-Raman spectra of individual nanotubes (PRL 98, 047402, 2007).

So far, all single-nanotube studies have been limited to linear optical properties. The more facinating phenomena related to nonlinear and quantum optical physics are still awaiting. We will develop advanced spectroscopy techniques to investigate such phenomena ranging from optical stark effect, Rabbi oscillation and coherent excitation in one-dimensional. Further, time resolved pump-probe measurements along individual nanotubes could yield direct information on carrier motion relevant to electrical and thermal transport. We are also collaborating with different groups in Berkeley to combine optical probe with mechanical, electrical, TEM and photo-emission characterizations.

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