title: Electronic structure of atomically precise graphene nanoribbons.
abstract: Some of the most intriguing properties of graphene are predicted for specifically designed nanostructures such as nanoribbons. Functionalities far beyond those known from extended graphene systems include electronic band gap variations related to quantum confinement and edge effects, as well as localized spin-polarized edge states for specific edge geometries. The inability to produce graphene nanostructures with the needed precision, however, has so far hampered the verification of the predicted electronic properties. Here, we report on the electronic band gap and dispersion of the occupied electronic bands of atomically precise graphene nanoribbons fabricated via on-surface synthesis. Angle-resolved photoelectron spectroscopy and scanning tunneling spectroscopy data from armchair graphene nanoribbons of width N = 7 supported on Au(111) reveal a band gap of 2.3 eV, an effective mass of 0.21 m(0) at the top of the valence band, and an energy-dependent charge carrier velocity reaching 8.2 × 10(5) m/s in the linear part of the valence band. These results are in quantitative agreement with theoretical predictions that include image charge corrections accounting for screening by the metal substrate and confirm the importance of electron-electron interactions in graphene nanoribbons.
authors.affiliation: Empa, Swiss Federal Laboratories for Materials Science and Technology, 8600 Dübendorf, Switzerland. pascal.ruffieux@empa.ch
authors.forename: Pascal
authors.initials: P
authors.lastname: Ruffieux
authors.forename: Jinming
authors.initials: J
authors.lastname: Cai
authors.forename: Nicholas C
authors.initials: NC
authors.lastname: Plumb
authors.forename: Luc
authors.initials: L
authors.lastname: Patthey
authors.forename: Deborah
authors.initials: D
authors.lastname: Prezzi
authors.forename: Andrea
authors.initials: A
authors.lastname: Ferretti
authors.forename: Elisa
authors.initials: E
authors.lastname: Molinari
authors.forename: Xinliang
authors.initials: X
authors.lastname: Feng
authors.forename: Klaus
authors.initials: K
authors.lastname: Müllen
authors.forename: Carlo A
authors.initials: CA
authors.lastname: Pignedoli
authors.forename: Roman
authors.initials: R
authors.lastname: Fasel
mesh_terms: D003198:Computer Simulation; D004579:Electron Transport; D006108:Graphite / Q000737:chemistry*; D008422:Materials Testing; D008956:Models, Chemical; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure*; D010316:Particle Size
chemical_list: D006108:Graphite