Direct observation of a dispersionless impurity band in hydrogenated graphene

D. Haberer,1 L. Petaccia,2 M. Farjam,3 S. Taioli,4,5 S. A. Jafari,3,6 A. Nefedov,7 W. Zhang,7,8 L. Calliari,4 G. Scarduelli,4 B. Dora,9 D. V. Vyalikh,10 T. Pichler,11 Ch. Wöll,7 D. Alfè,12,13,14 S. Simonucci,15 M. S. Dresselhaus,16 M. Knupfer,1 B. Büchner,1 and A. Grüneis1,11 1IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany 2Elettra Synchrotron Light Laboratory, Sincrotrone Trieste SCpA, S.S. 14 Km 163.5, 34149 Trieste, Italy 3School of Nano Science, Institute for Research in Fundamental Sciences (IPM), P.O. Box 19395-5531, Tehran, Iran 4Interdisciplinary Laboratory for Computational Science (LISC), FBK-CMM and University of Trento, Via Sommarive 18, I-38123 Trento, Italy 5Department of Physics, University of Trento, Via Sommarive 14, I-38100 Trento, Italy 6 Department of Physics, Sharif University of Technology, Tehran 11155-9161, Iran 7Institut für Funktionelle Grenzflächen (IFG), Karlsruher Institut für Technologie (KIT), Hermann-von-Helmholtz-Platz 1, D-76344 Eggenstein-Leopoldshafen, Germany 8National Synchrotron Radiation Laboratory, University of Science and Technology of China, 230029 Hefei, Anhui, People’s Republic of China 9Department of Physics, Budapest University of Technology and Economics, Budafoki t 8, H-1111 Budapest, Hungary 10Institut für Festkörperphysik, TU Dresden, Mommsenstrasse 13, D-01069 Dresden, Germany 11Faculty of Physics, University of Vienna, Strudlhofgasse 4, A-1090 Wien, Austria 12Department of Earth Sciences, University College London, Gower Street, London WC1E 6BT, UK 13Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, UK 14London Centre for Nanotechnology, University College London, Gower Street, London WC1E 6BT, UK 15Department of Physics, University of Camerino, Via Madonna delle Carceri 9, I-62032 Camerino, Italy 16Department of Physics and Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, MA 02139-4307, USA (Received 21 October 2010; revised manuscript received 22 February 2011; published 22 April 2011)