Dresden 2009 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 11: Metal substrates: Adsorption of organic / bio molecules II
O 11.5: Vortrag
Montag, 23. März 2009, 16:00–16:15, SCH A118
Stilbene - a molecular switch on surfaces — •Thorsten Ulrich Kampen1,3, Philipp Martin Schmidt-Weber1, Ralph Püttner2, Christine Kolczewski1, Klaus Hermann1, and Karsten Horn1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Berlin, Germany — 2Freie Universität Berlin, Institut für Experimentalphysik, Berlin, Germany — 3SPECS GmbH, Berlin, Germany
We have investigated the potential of Stilbene as a molecular switch on surfaces. In this study, Si(100) and Cu(110) serve as exemplary semiconductor and metal substrates. Using the StoBe software package and performing NEXAFS measurements on the cis and trans isomers in the gas phase, both isomers are clearly identified by the lineshape of the resonances. NEXAFS investigations, aided by the results from photoelectron spectroscopy, showed that the interaction of the orbitals at the C=C bridge of stilbene with the substrate atoms has a direct influence on the isomerisation process. The isomerisation requires an excitation into the unoccupied bridge orbitals. On Si(100), the bonding of the molecules to the surface takes place via this C=C bridge thereby inhibiting the isomerisation. On Cu(110) adsorbate-substrate bonding does not envolve the C=C bridge, and therefore does not inhibit the isomerisation. For different coverages cis-to-trans isomerisation with an overall conversion of about 25% is possible.