Regensburg 2010 – wissenschaftliches Programm
O 6.6: Vortrag
Montag, 22. März 2010, 12:30–12:45, H36
An unusual approach to the description of bonding of chemisorbed conjugated molecules on noble metals — •Gerold M. Rangger1, Lorenz Romaner2, Oliver T. Hofmann1, Michael G. Ramsey3, and Egbert Zojer1 — 1Institut für Festkörperphysik, Technische Universität Graz, Austria — 2Lehrstuhl für Atomistic Modeling and Design of Materials, Montanuniversität Leoben, Austria — 3Institut für Physik, Karl-Franzens Universität Graz, Austria
The deposition of organic monolayers on metals has attracted significant interest as a tool to modify surfaces in the field of molecular electronics.
We present a theoretical study of the acceptor F4TCNQ on Ag(111) and the donor viologen on Au(111). There, experiments show pronounced changes in the UPS spectra of the molecules due to strong interactions with the surfaces. To understand the bonding mechanism, we use a projection of the density of states onto atomic and molecular orbitals in combination with a crystal orbital overlap type population analysis. This enables analyzing the molecular orbital occupation and the determination of bonding and anti-bonding contributions of molecular/atomic orbitals on the energy scale. Only a simultaneous examination of adsorption induced changes of the molecular geometry (including a bending of the molecule) and of the interaction between molecule and metal allows to arrive at a consistent picture for the investigated chemisorption processes.