Berlin 2008 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 8: Metal Substrates: Adsorption of Organic/Bio Molecules I

O 8.3: Vortrag

Montag, 25. Februar 2008, 12:30–12:45, MA 041

Low temperature phases of NTCDA and PTCDA monolayers on Ag(111) — •Tim Laugks, Johannes Ziroff, and Friedrich Reinert — University of Würzburg, Experimental Physics II, 97074 Würzburg, Germany

The organic semiconductor molecule 1,4,5,8-naphtalene-tetracarboxylic dianhydride (NTCDA) and 3,4,9,10-perylene-tetracarboxylic-dianhydride (PTCDA) exhibit phase transitions and variances in the electronic structure for both samples at low temperatures and for low temperatures during the film preparation. These problems are subject of current research because the interface geometry is decisive for the growth mode of organic molecules and the electronic properties of the interface. To improve our understanding of these systems we prepare NTCDA/PTCDA monolayers on Ag(111) at substrate temperatures down to 100 K and monitor their properties in a range from room temperature systematically down to 10 K. We investigate the electronic structure at the various temperature dependant phases, discussing the photoemission parameters of the HOMO and the former LUMO features. These parameters (i.e. binding energy and width) show a significant variation across the phase transitions and therewith we suggest a model for the interactions between molecule and substrate.