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DS: Fachverband Dünne Schichten
DS 16: Functional Oxides
DS 16.7: Vortrag
Dienstag, 26. Februar 2008, 19:15–19:30, H 2032
Optical characterization of individual, thermally reduced graphene oxide sheets — Inhwa Jung1, •Matthias Vaupel2, Richard Piner1, and Rod Ruoff3 — 1Dept of Mechanical Engineering, 2145 Sheridan Road, Northwestern University, Evanston, IL 60208-3111, USA — 2Nanofilm Technologie GmbH, 37081 Göttingen, Germany — 3Dept of Mechanical Engineering, The University of Texas, 1 University Station, C2200, Austin, TX 78712-0292, USA
Graphite oxide is a layered material that can be exfoliated to form stable colloidal suspensions in water. At an appropriate concentration, evaporation of droplets of such a colloidal suspension on a surface yields individual graphene oxide sheets. This material is of interest as a filler for nano-composites as well as for use in new paper-like materials. A few layers or even one single layer of graphene oxide, including in its reduced form, where the O/C ratio is lower than in graphene oxide, are of potential interest in device applications. The optical dispersion functions of the refractive index and extinction coefficient of graphene oxide were measured by imaging spectroscopic ellipsometry on single and triple layers of graphene oxide. The results are compared with the results from confocal microscopy [1]. Dispersion parameters of a heap of graphene oxide sheets were also measured by conventional spectroscopic ellipso- metry and fit as effective medium. The effect of thermal treatment of graphene oxide, which renders the material conductive and reduces layer thickness, was explained. [1] Jung, I.; Pelton, M.; Piner. R.; Dikin. D.; Stankovich, S.; Watcharotone, S.; Hausner, M.; Ruoff, R. S. Nano Lett. 2007, NL0714177.