Berlin 2015 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 50: Graphene (organized by O)

TT 50.16: Poster

Dienstag, 17. März 2015, 18:15–21:00, Poster A

Polarization-dependent radiation patterns of Raman scattering from Graphene — •Harald Budde, Nicolas Coca Lopez, Xian Shi, and Achim Hartschuh — Department Chemie and CeNS, LMU München, Germany

Raman Scattering Spectroscopy is a powerful technique for studying graphene and other sp2 carbon materials [1]. We combined Raman Spectroscopy with back focal plane (BFP) imaging, a method used to visualize the angular distribution of emitted or scattered light. As an example BFP imaging allows to determine the orientation of single dipolar emitters [2, 3].

Graphene's Raman radiation pattern can be described as the incoherent sum of two orthogonal point dipole emitters despite its extended two-dimensional structure. Parameter-free model calculations using previously reported Raman polarization data are in excellent agreement with the observed radiation patterns of both G and 2D band. We show that the observed polarization ratio of the 2D band and the 2D/G intensity ratio depend on the numerical aperture of the microscope objective used. Finally, the detection efficiency in microscopic Raman measurements is extracted from calculated patterns and is in agreement with the experimental data.

[1] A. Ferrari, D. Basko, Nat. Nanotech. 8, 235-246, 2013.

[2] M. Lieb, J. Zavislan, L. Novotny, J. Opt. Soc. Am. B 21, 1210-1215, 2004.

[3] N. Hartmann, G. Piredda, J. Berthelot, G. Colas des Francs, A. Bouhelier, A. Hartschuh, Nano Lett. 12, 177-181, 2012.