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May 2012

Making a Map for Nanotube Exploration


Figures: Electron diffraction patterns and Rayleigh spectra of carbon nanotubes with different chiral indices. Inset, top, an illustration of a single nanotube suspended across a gapped substrate for measurement.

An international team of scientists headed by Feng Wang of the Materials Science Division of Berkeley Lab and Enge Wang of the International Center for Quantum Materials in Beijing, has mapped out an "atlas" of key structural and optical properties of carbon nanotubes. By painstakingly measuring both electron diffraction and optical scattering for hundreds of samples, the team created a reference to accelerate future nanotube studies for fundamental physics research as well as optoelectronic and photonic applications.

For electrons confined to nanotubes, the effects of quantum mechanics are amplified, making nanotubes a unique test-bed for studies of electron-electron interactions in one-dimensional systems. Wang's team moved to accelerate such studies by reducing the number of measurements needed to determine the basic structural and optical properties of a given nanotube.

Working with the Molecular Foundry's Shaul Aloni, the researchers performed both electron diffraction and optical scattering experiments on individual single-walled carbon nanotubes. They leveraged a one-to-one correspondence between nanotube structure and optical resonance to build a reference table covering hundreds nanotube variations. In the process, they also observed some of the exotic physics of confined electrons, marking the beginning of a systematic study enabled by their nanotube atlas.


"An atlas of carbon nanotube optical transitions," Kaihui Liu, Jack Deslippe, Fajun Xiao, Rodrigo B. Capaz, Xiaoping Hong, Shaul Aloni, Alex Zettl, Wenlong Wang, Xuedong Bai, Steven G. Louie, Enge Wang and Feng Wang, Nature Nanotechnology 7, 325 (2012).
This study was supported by the US National Science Foundation (NSF, CAREER grant 0846648, DMR10-1006184 and EEC-0832819 to the NSF Center for Integrated Nanomechanical Systems), the US Department of Energy (DOE, DE-AC02-05CH11231 and DE-AC02-05CH11231 to the Molecular Foundry), the National Natural Science Foundation of China (91021007, 10874218, 10974238, 20973195 and 50725209) and the Chinese Ministry of Science and Technology (2009DFA01290). Computational resources were provided by the NSF (through TeraGrid resources at the National Institute for Computational Sciences) and the DOE (through the National Energy Research Scientific Computing Centre at the Lawrence Berkeley National Laboratory). R.B.C. acknowledges support from Brazilian funding agencies CNPq, FAPERJ and INCT – Nanomateriais de Carbono.