Regensburg 2016 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 86: Graphene: Electronic Properties and Structure
(Joint session of DS, DY, HL, MA, O and TT organized by O)
TT 86.2: Talk
Friday, March 11, 2016, 10:45–11:00, S051
Excitons and the XNLD of higly oriented pyrolytic graphite and graphene - theory and experiment — •Dominik Legut1, Robert Laskowski2, Peter M. Oppeneer3, Christine Jansing4, Markus Gilbert4, Andreas Gaupp4, Hans-Christoph Mertins4, Andrey Sokolov5, Suk-Ho Choi6, Hud Wahab7, and Heiko Timmers7 — 1IT4Innovations Centre, VSB-TU Ostrava, Ostrava, Czech Republic — 2Institute of High Performance Computing, A*STAR, Singapore — 3Department of Physics and Astronomy, Uppsala, Sweden — 4FH Münster, Steinfurt, Germany — 5HZB, Berlin, Germany — 6Department of Applied Physics, Kyung Hee University, Korea — 7University of New South Wales Canberra, Canberra BC, Australia
Reflection spectra of the x-ray natural linear dichroism (XNLD) were calculated on highly oriented pyrolytic graphite (HOPG) and graphene. The π- and σ-excitations stemming from the carbon K-edge are considered. It was computed in the single electron picture within the framework of the standart DFT as the first step. For the better descriptions of the core-hole quasiparticle one can model the Slater transition state employing the supercell calculation with partial hole on one of the carbon atoms with the electron charge distributed over the valence states. Another approach is to solve Bethe-Salpeter equations for the many-body electronic effects. The latter approach clearly identify the excitonic features of π- and σ-excitations HOPG. The spectral shape of the reflectance and XNLD of all three modeles are compared with the experimental data.