Regensburg 2016 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 9: Graphene: Structure and Dynamics
(Joint session of DS, DY, HL, MA, O and TT organized by O)

TT 9.8: Talk

Monday, March 7, 2016, 12:30–12:45, H24

Determination of the optical constants of graphene at the carbon K-edge by transmission spectroscopy — •Christine Jansing¹, Hans-Christoph Mertins¹, Andreas Gaupp¹, Andrey Sokolov², Markus Gilbert¹, Andreas Schümmer¹, Hud Wahab³, Heiko Timmers³, Suk-Ho Choi⁴, and Dominik Legut⁵ — ¹Münster University of Applied Sciences, Stegerwaldstr. 39, D-48565 Steinfurt — ²HZB, Albert Einstein Str. 15, D-12489 Berlin — ³University of New South Wales, Canberra, ACT 2600, Australia — ⁴Kyung Hee University, Yongin 446-701, Korea — ⁵IT4Innovations Center, VSB-Technical University of Ostrava, CZ-708 33 Ostrava, Czech Republic

The transmission of linearly polarized synchrotron radiation through quasi-free-standing graphene, supported by a Si3N4-membrane, has been measured across the carbon K-edge. From the measured absorption spectrum, that represents the imaginary part, the real part of the refractive index has been extracted via a Kramers-Kronig transformation. Based on these detailed optical parameters, reflection spectra have been simulated for linearly polarized soft x-ray light incident on graphene-metal systems. Importantly, the simulations include the interference of light reflected from graphene and from light reflected from the metallic substrate, respectively. In addition the optical constants are compared to the ones obtained by various density function theory calculations using single-electron framework as well as the more complex many-body approaches to the electronic structure of free-standing graphene.