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Electronic structure of a subnanometer wide bottom-up fabricated graphene nanoribbon: End states, band gap, and dispersion

2012; American Physical Society; Volume: 86; Issue: 8 Linguagem: Inglês

10.1103/physrevb.86.085444

1550-235X

Christopher Bronner, Felix Leyßner, Stephan Stremlau, Manuel Utecht, Peter Saalfrank, Tillmann Klamroth, Petra Tegeder,

Surface and Thin Film Phenomena

Angle-resolved two-photon photoemission and high-resolution electron energy loss spectroscopy are employed to derive the electronic structure of a sub-nanometer tomically precise quasi-one-dimensional graphene nanoribbon (GNR) on Au(111). We resolved occupied and unoccupied electronic bands including their dispersion and determined the and gap, which possesses an unexpected large value of 5.1 eV. Supported by density functional theory (DFT) calculations for the idealized infinite polymer and finite size oligomers an unoccupied non-dispersive electronic state with an energetic position in the middle of the band gap of the GNR could be identified. This state resides at both ends of the ribbon (end state) and is only found in the finite sized systems, i.e. the oligomers.