Regensburg 2010 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 50: Graphene and Carbon Nanotubes
HL 50.2: Vortrag
Donnerstag, 25. März 2010, 09:45–10:00, H15
What’s the color of graphene ? Black and dark or white and bright ? — •Rainer Stöhr1, Roman Kolesov1, Fedor Jelezko1, Jens Pflaum2, and Jörg Wrachtrup1 — 13rd Physics Institute, Stuttgart University — 2Julius-Maximilians-University of Würzburg, Experimental Physics VI and Bavarian Centre for Applied Energy Research e.V. (ZAE Bayern)
In this contribution, we report on the first, to our knowledge, study of non-linear optical properties of graphene and thin graphite flakes. We particularly focus on graphene under picosecond pulsed infrared excitation yielding to a spectrally broad non-linear upconverted luminescence. Several key experiments are discussed to illustrate its characteristics and to clarify its nature. Comparing the effective non-linear coefficient deff of that process with that of other highly non-linear materials shows that graphene reveals extraordinary performance in terms of its non-linear optical properties. Through rigorous study of this upconverted luminescence as a function of the number of graphite layers, incident laser power and substrate material we introduce a new and superior tool for imaging and quantifying single and multilayered graphene flakes. Comparing this new imaging method with standard techniques like atomic force microscopy and Raman spectroscopy will evidence its excellent properties in terms of imaging quality and the unambiguous thickness determination of multilayer graphene flakes up to twenty layers.