Farhat, H. and Son, H. and Samsonidze, Ge. G. and Reich, S. and Dresselhaus, M. S. and Kong, J. (2007) Phonon softening in individual metallic carbon nanotubes due to the Kohn anomaly. PHYSICAL REVIEW LETTERS, 99 (14).
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We have studied the line shape and frequency of the G band Raman modes in individual metallic single walled carbon nanotubes (M-SWNTs) as a function of Fermi level (epsilonF) position, by tuning a polymer electrolyte gate. Our study focuses on the data from M-SWNTs where explicit assignment of the G- and G+ peaks can be made. The frequency and line shape of the G- peak in the Raman spectrum of M-SWNTs is very sensitive to the position of the Fermi level. Within ±[h-bar]omega/2 (where [h-bar]omega is the phonon energy) around the band crossing point, the G- mode is softened and broadened. In contrast, as the Fermi level is tuned away from the band crossing point, a semiconductinglike G band line shape is recovered both in terms of frequency and linewidth. Our results confirm the predicted softening of the A-symmetry LO phonon mode frequency due to a Kohn anomaly in M-SWNTs.
|Subjects:||Physical Science > Nanoelectronics|
Physical Science > Quantum phenomena
Material Science > Nanostructured materials
|Deposited By:||Anuj Seth|
|Deposited On:||26 May 2009 15:26|
|Last Modified:||26 May 2009 15:26|
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