Kohn anomalies in graphene nanoribbons

Ken Ichi Sasaki, Masayuki Yamamoto, Shuichi Murakami, Riichiro Saito, Mildred S. Dresselhaus, Kazuyuki Takai, Takanori Mori, Toshiaki Enoki, Katsunori Wakabayashi

Research output: Contribution to journalArticlepeer-review

50 Citations (Scopus)


The quantum corrections to the energies of the Γ point optical phonon modes (Kohn anomalies) in graphene nanoribbons (NRs) are investigated. We show theoretically that the longitudinal optical (LO) modes undergo a Kohn anomaly effect, while the transverse optical (TO) modes do not. In relation to Raman spectroscopy, we show that the longitudinal optical modes are not Raman active near the zigzag edge, while the transverse optical modes are not Raman active near the armchair edge. These results are useful for identifying the orientation of the edge of graphene nanoribbons by G band Raman spectroscopy, as is demonstrated experimentally. The differences in the Kohn anomalies for nanoribbons and for metallic single-wall nanotubes are pointed out, and our results are explained in terms of pseudospin effects.

Original languageEnglish
Article number155450
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number15
Publication statusPublished - 2009 Oct 27

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics


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