Abstract Submitted to the    NANOTUBE'06 Conference:

The Raman fingerprint of graphene

Andrea C. Ferrari ¹, Vittorio Scardaci ², Jannik Meyer ³, Cinzia Casiraghi ², Michele Lazzeri ⁴, Francesco Mauri ⁴, Stefano Piscanec ², Da Jiang ⁵, Kostya S Novoselov ⁵, Andre K Geim ⁵

¹ University of Cambridge
² Department of Engineering, University of Cambridge, Cambridge CB3 0FA, UK
³ Max Planck Institute for Solid State Research, Stuttgart 70569, Germany
⁴ Institut de Mineralogie et de Physique des Milieux Condenses, Paris cedex 05, France
⁵ Department of Physics and Astronomy, University of Manchester, Manchester, M13 9PL, UK

acf26@eng.cam.ac.uk

IV. Raman Characterization of Nanotubes

Graphene, a single, one-atom-thick sheet of carbon atoms in a honeycomb lattice, is the two-dimensional (2D) building block for carbon allotropes of every other dimensionality. It can be stacked into 3D graphite, rolled into 1D nanotubes, or wrapped into 0D buckyballs. Only very recently graphene has been produced in its free state [1]. This has fuelled research in 2D carbons and highlighted their remarkable electronic properties [2,3]. Graphene is a ballistic conductor in which electrons mimic the behaviour of massless, relativistic particles [2,3].. Electron transport is governed by the (relativistic) Dirac equation (rather than the Schrödinger equation) and this allows access to the rich and subtle physics of quantum electrodynamics in a condensed matter experiment Here we present the first Raman measurements of an isolated graphene layer [4]. These are supported by the definitive identification of free-standing single and bi-layers by transmission electron microscopy and electron diffraction. We show that graphene’s electronic structure is uniquely captured in its Raman spectrum. We identify the unique features of its Raman spectrum, which fingerprints graphene amongst all other carbon allotropes. We compare its spectrum to that of n graphene layers having the same stacking as graphite, with n=2 to 28. We demonstrate that the Raman spectrum evolution with increasing number of layers uniquely reflects the evolution of the electronic structure and electron-phonon interactions. This makes Raman spectroscopy is a quick, high-throughput, non-destructive technique for the unambiguous identification of graphene layers. Finally we discuss the implications for the interpretation of the Raman spectra of single and double wall nanotubes.

1 K. S. Novoselov et al. Proc. Natl. Acad. Sci. USA 102, 10451 (2005)
2 K S Novoselov et al, Science 306, 666 (2004); Nature 438, 197 (2005)
3 Y Zhang et al Nature 438, 201 (2005)
4 A. C. Ferrari et al submitted (2006)

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