Dresden 2014 – scientific programme

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O: Fachverband Oberflächenphysik

O 37: Posters: Plasmonics, Electronic Structure and Spin-Orbit Interaction, Semiconductor and Insulator Surfaces, Nanostructures

O 37.73: Poster

Tuesday, April 1, 2014, 18:30–22:00, P2

Adsorption of PTCDA on KCl and NaCl surfaces — •Hazem Aldahhak, Wolf Gero Schmidt, and Eva Rauls — Theoretische Physik, Universität Paderborn

In recent years, various highly regular supramolecular architectures of self-organized molecules on crystals have been designed and used in the bottom-up device technology. In the past, metal surfaces have frequently been used as substrate. However, metal substrates induce screening and quenching effects and thus hamper the detailed spectroscopy of the adsorbed overlayer. In contrast, molecular adsorption on ionic crystals like sodium or potassium chloride opens the possibility to study electronically decoupled molecules. Here we present density-functional theory calculations on the adsorption of single PTCDA molecules on KCl and NaCl (100) surfaces. Thereby, the adsorption on flat surfaces as well as on stepped substrates has been investigated. In order to unterstand and rationalize the adsorption mechanisms leading to the formation of these structures, a large variety of interface geometries was studied and analyzed with respect to the contribution of ionic, covalent and van-der-Waals interactions between adsorbates and substrates. The influence of the substrate and bonding mechanism on the molecular electronic structure has been investigated in detail and compared with the experimental data available. The calculation of the potential energy surface (PES) allows us to determine the activation energy for the mobile molecules on the surface.