Dresden 2017 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 29: Organic-Inorganic Hybrid Systems and Organic Films IV

O 29.5: Vortrag

Dienstag, 21. März 2017, 11:30–11:45, WIL A317

Integer charge transfer induced by insulating layer — •Michael Hollerer¹, Daniel Lüftner¹, Philipp Hurdax¹, Thomas Ules¹, Simon Weiß^2,3, Sergey Soubatch^2,3, Frank Stefan Tautz^2,3, 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.