title: Electronic states of a single layer of pentacene: standing-up and flat-lying configurations.
abstract: The electronic properties of a single layer (SL) of pentacene molecules are investigated by high-resolution UV photoemission and near-edge X-ray absorption spectroscopy in different configurations of the SL, either standing up on an aromatic self-assembled monolayer or planar on a bare Cu(001) substrate. The weakly interacting pentacene molecules in the standing-up SL present a semiconducting character, and the empty states distribution reflects that of gas-phase pentacene, while the planar pentacene-Cu system shows a metallic interface with redistribution of the empty molecular states. The highest-occupied molecular orbital lineshape in the weakly interacting SL shows a double structure, attributed to two nonequivalent molecules in the ordered configuration.
authors.affiliation: Dipartimento di Fisica, Università di Roma La Sapienza, Piazzale Aldo Moro 2, I-00185 Roma, Italy. betti@roma1.infn.it
authors.forename: Maria Grazia
authors.initials: MG
authors.lastname: Betti
authors.forename: Aloke
authors.initials: A
authors.lastname: Kanjilal
authors.forename: Carlo
authors.initials: C
authors.lastname: Mariani
mesh_terms: D008968:Molecular Conformation; D009279:Naphthacenes / Q000737:chemistry*
chemical_list: D009279:Naphthacenes; C523499:pentacene