Berlin 2012 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 34: Poster Session I (Graphene; Plasmonics and nanooptics; Coherence and coherent control in nanophotonics and plasmonics)
O 34.16: Poster
Dienstag, 27. März 2012, 18:15–21:45, Poster E
Theoretical modelling and interpretation of the C 1s→π*,σ* X-ray absorption spectra of H2O(NH3)/graphene — •Elena Voloshina1, Roman Ovcharenko1,2, Aleksander Shulakov2, Beate Paulus1, and Yuriy Dedkov3 — 1Physikalische und Theoretische Chemie, Freie Universität Berlin, Germany — 2V. A. Fock Institute of Physics, Saint-Petersburg State University, Russia — 3SPECS Surface Nano Analysis GmbH, Germany
Recently, adsorption of polar molecules on graphene/Ni(111) was investigated by means of angle-resolved photoelectron spectroscopy (ARPES) and X-ray absorption spectroscopy (XAS) [1]. It was found, that adsorption of H2O and NH3 leads to the noticeable modification of the XAS C K-edge spectra indicating the orbital mixing of the valence band states of graphene and adsorbates. Further analysis of the obtained results allows assuming the site-selective adsorption for the two studied adsorbates. However, neither position nor orientation of the adsorbate were determined. In order to clarify these aspects, we performed the first-principles electronic structure calculations on the H2O/graphene and NH3/graphene systems as well as modelling the C K-edge XAS spectra of these systems. The dynamical core-hole screening effects in the XAS spectra were taken into account via the multiband Mahan-Nozieres-De Dominicis (MND) theory [2]. The presented theoretical results are compared to available previously published theoretical data as well as experimental observations.
[1] S. Böttcher et al. Nanoscale Res. Lett. 6, 214 (2011).
[2] O. Wessely et al. Phys. Rev. B 73, 075402 (2006).