title: Energy level alignment at metal-octaethylporphyrin interfaces.
abstract: We studied the electronic structure of copper-octaethylporphyrin (CuEOP) adsorbed on three metal surfaces--Ag(001), Ag(111), and Cu(111)--by means of ultraviolet photoelectron spectroscopy (UPS). The adsorption-induced work function shifts saturate roughly beyond two monolayers. The saturation values are substrate dependent, negative, and range from -1.30 to -0.85 eV. This shift is larger than that for tetraphenylporphyrins. The two highest occupied molecular orbitals (HOMO and HOMO-1) of the organic are clearly resolved in the UPS spectra. The origin of the negative work function shift is discussed.
authors.affiliation: NCCR Nanoscale Science, Institute of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland. audrius.alkauskas@unibas.ch
authors.forename: A
authors.initials: A
authors.lastname: Alkauskas
authors.forename: L
authors.initials: L
authors.lastname: Ramoino
authors.forename: S
authors.initials: S
authors.lastname: Schintke
authors.forename: M
authors.initials: M
authors.lastname: von Arx
authors.forename: A
authors.initials: A
authors.lastname: Baratoff
authors.forename: H-J
authors.initials: HJ
authors.lastname: Güntherodt
authors.forename: T A
authors.initials: TA
authors.lastname: Jung