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G – and G + in the Raman spectrum of isolated nanotube: a study on resonance conditions and lineshape
Author(s) -
Telg H.,
Fouquet M.,
Maultzsch J.,
Wu Y.,
Chandra B.,
Hone J.,
Heinz T. F.,
Thomsen C.
Publication year - 2008
Publication title -
physica status solidi (b)
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.51
H-Index - 109
eISSN - 1521-3951
pISSN - 0370-1972
DOI - 10.1002/pssb.200879658
Subject(s) - raman spectroscopy , nanotube , resonance (particle physics) , phonon , materials science , metal , coupling (piping) , atomic physics , carbon nanotube , condensed matter physics , molecular physics , nuclear magnetic resonance , nanotechnology , physics , optics , metallurgy
We analyze the high‐energy Raman modes, G + and G – , in a pair of one metallic and one semiconducting nanotube grown across a 100 mm wide slit. By combining Raman resonance profiles of the radial breathing mode and the high‐energy modes, we assign the broad G – peak to a metallic and the G + peak to a semiconducting nanotube. Considering theoretical predictions we show that both peaks, G – and G + , originate from the LO phonon. The G – peak is the longitudinal mode of the metallic tube; it is broadened and downshifted due to strong electron‐phonon coupling in the metallic nanotube. The G + peak is due to the longitudinal mode in the semiconducting tube. An asymmetric lineshape of the G – peak agrees with observations of the asymmetry to be an intrinsic feature of metallic nanotubes. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)