Dresden 2017 – scientific programme
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O: Fachverband Oberflächenphysik
O 29: Organic-Inorganic Hybrid Systems and Organic Films IV
O 29.5: Talk
Tuesday, March 21, 2017, 11:30–11:45, WIL A317
Integer charge transfer induced by insulating layer — •Michael Hollerer1, Daniel Lüftner1, Philipp Hurdax1, Thomas Ules1, Simon Weiß2,3, Sergey Soubatch2,3, Frank Stefan Tautz2,3, Georg Koller1, Peter Puschnig1, Martin Sterrer1, and Mike Ramsey1 — 1Insitute of Physics, University of Graz, NAWI Graz, Universitätsplatz 5, 8010 Graz, Austria — 2Peter Grünberg Insitut (PGI-3), Forschungszentrum Jülich, 52425, Jülich, Germany — 3Jülich Achen Research Alliance (JARA), Fundamentals of Future Information Technology, 52425, Jülich, Germany
While it is becoming accepted that charge transfer can occur across thin dielectric films on metal substrates, particularly for organic overlayers, the occupancy of the lowest unoccupied molecular orbital (LUMO), whether fractional or integer, and the distribution of the charged molecules within the layer is under debate. Herein we present a comprehensive analysis of the charge transfer phenomena, facilitated by the strong reduction of the work function, in the model system pentacene on thin MgO(001) on Ag(001). Using scanning tunneling microscopy (STM) and angular resolved photoemission supported by density functional theory we are able to unambiguously deduce integer occupation of all molecules in the monolayer film on MgO(001)/Ag(001) compared to fractional occupation on the bare Ag(100) substrate. Moreover, the energy of the peaks observed in scanning tunneling spectroscopy, above and below the Fermi level, can be directly related to those of the singly occupied and singly unoccupied molecular states.