Coherent nanoscale optical-phonon wave packet in graphene layers

I. Katayama, K. Sato, S. Koga, J. Takeda, S. Hishita, H. Fukidome, M. Suemitsu, M. Kitajima

Research output: Contribution to journalArticlepeer-review

9 Citations (Scopus)


Coherent large-wave-vector phonons in graphene layers were excited by using a 7.5-fs ultrashort laser, and observed by wavelength-resolved pump-probe transient reflectivity spectroscopy. Inter-Dirac-cone electron scattering mediated by edges and defects in graphene layers drives large-wave-vector coherent D-mode phonons near the Dirac point (K point) of the Brillouin zone. In contrast to the normal coherent phonons generated with first-order Raman process, phonon chirp is observed, and amplitude and frequency strongly change depending on the probed wavelength. The results are discussed on the basis of doubly resonant Raman scattering process, demonstrating that generated D-mode coherent phonons can propagate as nanoscale optical-phonon wave packets.

Original languageEnglish
Article number245406
JournalPhysical Review B - Condensed Matter and Materials Physics
Issue number24
Publication statusPublished - 2013 Dec 4


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