Berlin 2018 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 48: Poster: 2D Materials beyond Graphene: TMDCs, Silicene and Relatives

O 48.1: Poster

Dienstag, 13. März 2018, 18:15–20:30, Poster A

Chemical and electronic decoupling of organic molecules by a monolayer of hexagonal boron nitride — •Christine Brülke¹, Timo Heepenstrick¹, Ina Krieger¹, Xiaosheng Yang², Simon Weiss², Frank Stefan Tautz², Serguei Soubatch² und Moritz Sokolowski¹ — ¹Institut für Physikalische und Theoretische Chemie der Universität Bonn — ²Peter Grünberg Institut, Forschungszentrum Jülich

Hexagonal boron nitride (hBN) is a widely studied material due to its similarity to graphene and its properties as a wide band-gap insulator. We report on the ability of one monolayer hBN to electronically and chemically decouple one monolayer of PTCDA from the Cu(111) surface. Using spot profile analysis low energy electron diffraction (SPA-LEED) and scanning tunneling microscopy (STM) we find a big similarity of the PTCDA monolayer to the (102) plane of the bulk crystal. Investigations via photoelectron spectroscopy (XPS and UPS) show electronic decoupling of the molecules from Cu(111) by the hBN monolayer. The HOMO of the monolayer is located at -2.5 eV below E_F, in accordance with previous findings for multilayers of PTCDA. Normal incidence standing wave experiments (NIXSW) reveal that the vertical binding distance of PTCDA to the hBN layer is very large (3.38 Å) and that the out-of-plane distortion of the molecule is very minute (< 0.1 Å). This points to a weak physisorptive bonding in contrast to the chemisorptive bonding found for PTCDA on Cu(111).