Electronic and geometric structure of the PTCDA/Ag(110) interface probed by angle-resolved photoemission.

ROM 2012-9
Institute: (1) Universität Würzburg, Experimentelle Physik VII and Röntgen Research Center for Complex Material Systems RCCM, 97074 Würzburg, Germany and Karlsruher Institut für Technologie KIT, Gemeinschaftslabor für Nanoanalytik, 76021 Karlsruhe, Germany (2) Peter Grünberg Institute (PGI-6), JARA-FIT, Research Center Jülich, 52425 Jülich, Germany and NanoESCA beamline, Sincrotrone Trieste, in Area Science Park, 34149 Basovizza, Trieste, Italy (3) Omicron NanoTechnology GmbH, Limburger Strasse 75, 65232 Taunusstein, Germany
Instrument: NanoESCA

The properties of molecular films are determined by the geometric structure of the first layers near the interface. These are in contact with the substrate and feel the effect of the interfacial bonding, which particularly, for metal substrates, can be substantial. For the model system 3,4,9,10-perylenetetracarboxylic dianhydride on Ag(110), the geometric structure of the first monolayer can be modified by preparation parameters. This leads to significant differences in the electronic structure of the first layer. Here, we show that, by combining angle-resolved photoelectron spectroscopy with low-energy electron diffraction, we cannot only determine the electronic structure of the interfacial layer and the unit cell of the adsorbate superstructure, but also the arrangement of the molecules in the unit cell. Moreover, in bilayer films, we can distinguish the first from the second layer and, thus, study the formation of the second layer and its influence on the buried interface.