Softening of the Radial Breathing Mode in Metallic Carbon Nanotubes

ORAL

Abstract

In this work, the Fermi level $(\epsilon_{\rm F})$ dependence of the radial breathing mode (RBM) of metallic single walled carbon nanotubes (M-SWNTs) has been investigated. In situ Raman spectra were obtained from several individual M-SWNTs while varying $\epsilon_{\rm F}$ electrochemically. The RBM frequency of an intrinsic M-SWNT is shown to be downshifted relative to highly doped tubes by $\sim2{\rm cm}^{-1}$. The downshift is greatest for small diameter and small chiral angle nanotubes. Most tubes do not show any change in RBM linewidth. A comparison is drawn between the RBM and the G-band ($A_{\rm LO}$ phonon) with respect to the $\epsilon_{\rm F}$ dependence of their frequencies and linewidths.

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Authors

  • Hootan Farhat

    • MIT

  • Ken-ichi Sasaki

    • Department of Quantum Matter, AdSM, Hiroshima University, Japan
    • Hiroshima University

  • Martin Kalbac

    • Academy of Sciences of the Czech Republic

  • Mario Hofmann

    • MIT

  • Riichiro Saito

    • Tohoku University

  • Mildred Dresselhaus

    • Massachusetts Institute of Technology
    • MIT
    • Department of Physics and 2. Department of Electrical Engineering and Computer Science, MIT
    • ECCS, MIT, USA

  • Jing Kong

    • Massachusetts Institute of Technology
    • MIT
    • Department of Electrical Engineering and Computer Science, MIT