title: Comprehensive studies of the electronic structure of pristine and potassium doped chrysene investigated by electron energy-loss spectroscopy.
abstract: We have performed electron energy-loss spectroscopy studies in order to investigate the electronic properties of chrysene molecular solids. The valence band electronic excitation spectra and the C 1s core level excitations have been measured for pristine and potassium doped chrysene. The core level studies show a fine structure which signals the presence of four close lying conduction bands close to the Fermi level. Upon potassium doping, these bands are filled with electrons, and we have reached a doping level of about K(2.7)chrysene. Furthermore, undoped chrysene is characterized by an optical gap of about 3.3 eV and five, relatively weak, excitonic features following the excitation onset. Doping induces major changes in the electronic excitation spectra, with a new, prominent low energy excitation at about 1.3 eV. The results of a Kramers-Kronig analysis indicate that this new feature can be assigned to a charge carrier plasmon in the doped material, and momentum dependent studies reveal a negative plasmon dispersion.
authors.affiliation: IFW Dresden, P.O. Box 270116, D-01171 Dresden, Germany.
authors.forename: Friedrich
authors.initials: F
authors.lastname: Roth
authors.forename: Benjamin
authors.initials: B
authors.lastname: Mahns
authors.forename: Ronny
authors.initials: R
authors.lastname: Schönfelder
authors.forename: Silke
authors.initials: S
authors.lastname: Hampel
authors.forename: Markus
authors.initials: M
authors.lastname: Nohr
authors.forename: Bernd
authors.initials: B
authors.lastname: Büchner
authors.forename: Martin
authors.initials: M
authors.lastname: Knupfer
mesh_terms: D002911:Chrysenes / Q000737:chemistry*; D004583:Electrons; D037741:Fullerenes / Q000737:chemistry*; D015394:Molecular Structure; D011188:Potassium / Q000737:chemistry*; D046590:Spectroscopy, Electron Energy-Loss
chemical_list: D002911:Chrysenes; D037741:Fullerenes; C530172:pristine (C60); C031180:chrysene; D011188:Potassium