title: Scanning tunneling microscopy/spectroscopy of picene thin films formed on Ag(111).
abstract: Using ultrahigh-vacuum low-temperature scanning tunneling microscopy and spectroscopy combined with first principles density functional theory calculations, we have investigated structural and electronic properties of pristine and potassium (K)-deposited picene thin films formed in situ on a Ag(111) substrate. At low coverages, the molecules are uniformly distributed with the long axis aligned along the [112̄] direction of the substrate. At higher coverages, ordered structures composed of monolayer molecules are observed, one of which is a monolayer with tilted and flat-lying molecules resembling a (11̄0) plane of the bulk crystalline picene. Between the molecules and the substrate, the van der Waals interaction is dominant with negligible hybridization between their electronic states; a conclusion that contrasts with the chemisorption exhibited by pentacene molecules on the same substrate. We also observed a monolayer picene thin film in which all molecules were standing to form an intermolecular π stacking. Two-dimensional delocalized electronic states are found on the K-deposited π stacking structure.
authors.affiliation: The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
authors.forename: Yasuo
authors.initials: Y
authors.lastname: Yoshida
authors.affiliation: Department of Physics, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Hung-Hsiang
authors.initials: HH
authors.lastname: Yang
authors.affiliation: Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Hsu-Sheng
authors.initials: HS
authors.lastname: Huang
authors.affiliation: Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Shu-You
authors.initials: SY
authors.lastname: Guan
authors.affiliation: Department of Physics and Earth Science Department, University of the Ryukyus, 1 Nishihara, Okinawa 903-0213, Japan.
authors.forename: Susumu
authors.initials: S
authors.lastname: Yanagisawa
authors.affiliation: The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
authors.forename: Takuya
authors.initials: T
authors.lastname: Yokosuka
authors.affiliation: Department of Physics, National Taiwan University, Taipei 106, Taiwan.
authors.forename: Minn-Tsong
authors.initials: MT
authors.lastname: Lin
authors.affiliation: Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Wei-Bin
authors.initials: WB
authors.lastname: Su
authors.affiliation: Institute of Physics, Academia Sinica, Nankang, Taipei 11529, Taiwan.
authors.forename: Chia-Seng
authors.initials: CS
authors.lastname: Chang
authors.affiliation: The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
authors.forename: Germar
authors.initials: G
authors.lastname: Hoffmann
authors.affiliation: The Institute of Solid State Physics, The University of Tokyo, Kashiwa 277-8581, Japan.
authors.forename: Yukio
authors.initials: Y
authors.lastname: Hasegawa