Chiral Index Dependence of the G(+) and G(-) Raman Modes in Semiconducting Carbon Nanotubes

Center for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
ACS Nano (Impact Factor: 12.88). 12/2011; 6(1):904-11. DOI: 10.1021/nn2044356
Source: PubMed


Raman spectroscopy on the radial breathing mode is a common tool to determine the diameter d or chiral indices (n,m) of single-wall carbon nanotubes. In this work we present an alternative technique to determine d and (n,m) based on the high-energy G(-) mode. From resonant Raman scattering experiments on 14 highly purified single chirality (n,m) samples we obtain the diameter, chiral angle, and family dependence of the G(-) and G(+) peak position. Considering theoretical predictions we discuss the origin of these dependences with respect to rehybridization of the carbon orbitals, confinement, and electron-electron interactions. The relative Raman intensities of the two peaks have a systematic chiral angle dependence in agreement with theories considering the symmetry of nanotubes and the associated phonons.

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    • "However, G−/ G+ modes being in-plane vibrations are less sensitive to environmental changes [21]. Therefore, a rough estimation of the diameter (d) of CNTs deposited in the transistor was obtained by evaluating the splitting of the G− and G+ bands following an empirical formula recently proposed by Telg et al. [12]. "
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