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O: Fachverband Oberflächenphysik
O 60: Poster Session IV (Solid/liquid interfaces; Semiconductors; Oxides and insulators; Graphene; Plasmonics and nanooptics; Electronic Structure; Surface chemical reactions; Heterogeneous catalysis)
O 60.37: Poster
Wednesday, March 16, 2011, 17:30–21:00, P4
EELS study of epitaxial graphene/Ni(111) and graphene/Au/Ni(111) — •Alexander Generalov1, Konstantin Simonov2, Karsten Horn1, and Yuriy Dedkov1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2V.A. Fock Institute of Physics, St. Petersburg State University, St. Petersburg, Russia
Due to its surface sensitivity, the electron energy loss spectroscopy in reflection mode (REELS) with electron beam of low primary energy is very suitable for investigation of true and quasi two-dimensional (2D) systems. The goal of the present work is the comparative study of strongly bonded graphene/Ni(111) and quasi free standing graphene/Au/Ni(111) systems by means of REELS spectroscopy.
The graphene/Ni(111) system was prepared via thermal decomposition of ethylene C2H4 on the Ni(111) single crystal surface. The 2 ML Au layer was intercalated underneath graphene on Ni(111) via thermal annealing of the Au/graphene/Ni(111) system. After intercalation of gold under graphene the features in EELS spectrum which are characteristic of graphene/Ni(111) interface disappear and shift of π plasmon to the lower loss energy is observed indicating the transition of initial system of strongly bonded graphene on Ni(111) to a graphite like state. Application of the free-electron model for the dependence of surface plasma frequency on density of free carriers to our experimental results gives the value of graphene doping from Ni(111) substrate to be about of 0.05e per carbon atom relative to quasi free standing graphene on Au/Ni(111).