Dresden 2011 – wissenschaftliches Programm
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MM: Fachverband Metall- und Materialphysik
MM 17: Topical Session TEM V
MM 17.2: Vortrag
Dienstag, 15. März 2011, 14:30–14:45, IFW A
2D interband plasmons in free-standing graphene — •Michael Kinyanjui1, Philipp Wachsmuth1, Jannik Meyer2, Christian Kramberger2, Thomas Pichler2, Gerd Benner3, and Ute Kaiser1 — 1Central facility of electron microscopy, University of Ulm, Albert Einstein Allee 11, 89068 Ulm, Germany — 2Faculty of physics, University of Vienna, Strudlhofgasse 4, A-1090 Vienna, Austria — 3Carl Zeiss NTS GmbH, Carl-Zeiss-Str. 56 73447, Oberkochen, Germany
Due to its unique electronic structure 2 dimensional (2D) graphene offers a means by which many-body interactions such quasi-particle excitations (electron-hole pair interactions), collective excitations of valence electrons (plasmons) and lattice vibrations (phonons) can be studied [1]. We investigated the properties of the π-plasmon excitations in free-standing monolayer of graphene using electron energy loss spectroscopy (EELS). The investigations were conducted at a specially developed low voltage transmission electron microscope operated at 20 kV. We study the dispersion of the π Plasmon peak for momentum transfers 0 Å-1 < q < 0.5 Å-1. In this momentum transfer range we observe the π plasmon as being characterized by a quasi-linear dispersion. In addition, the π plasmon excitations are shown to lie above the single-particle excitations (SPE) in mono-layer graphene. These results are discussed and compared to results obtained from single-walled carbon nanotubes (SWCNT).
[1] A. H. Castro Neto, F. Guinea, N. M. R. Peres, K.S. Novosolev, A. K. Geim, Rev. Mod. Phys. 81, 109 (2009)