Time-Resolved Two-Photon Photoemission of Unoccupied Electronic States of Periodically Rippled Graphene on Ru(0001)

N. Armbrust, J. Güdde, P. Jakob, and U. Höfer
Phys. Rev. Lett. 108, 056801 – Published 31 January 2012
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Abstract

The unoccupied electronic states of epitaxially grown graphene on Ru(0001) have been explored by time- and angle-resolved two-photon photoemission. We identify a Ru derived resonance and a Ru/graphene interface state at 0.91 and 2.58 eV above the Fermi level, as well as three image-potential derived states close to the vacuum level. The most strongly bound, short-lived, and least dispersing image-potential state is suggested to have some quantum-well character with a large amplitude below the graphene hills. The two other image-potential states are attributed to a series of slightly decoupled states. Their lifetimes and dispersions are indicative of electrons moving almost freely above the valley areas of the moiré superstructure of graphene.

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  • Received 29 September 2011

DOI:https://doi.org/10.1103/PhysRevLett.108.056801

© 2012 American Physical Society

Authors & Affiliations

N. Armbrust1, J. Güdde1, P. Jakob1, and U. Höfer1,2

  • 1Fachbereich Physik und Zentrum für Materialwissenschaften, Philipps-Universität, 35032 Marburg, Germany
  • 2Donostia International Physics Center (DIPC), 20018 San Sebastián, Spain

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Issue

Vol. 108, Iss. 5 — 3 February 2012

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