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O: Fachverband Oberflächenphysik
O 32: Semiconductor Substrates
O 32.4: Talk
Tuesday, March 27, 2007, 16:30–16:45, H39
Photoisomerization of Stilbene on Si(100): Gaining further insight by combined theoretical and experimental C 1s NEXAFS spectra — •Christine Kolczewski1, Klaus Hermann1, Ralph Püttner2, Philipp Martin Schmidt1, Thorsten Kampen1, and Karsten Horn1 — 1Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Deutschland — 2Freie Universität Berlin, Institut für Experimentalphysik, Arnimallee 14, 14195 Berlin, Deutschland
Stilbene is a prototype molecule for studying photoinduced cis-trans isomerization. To gain further insight into the isomerization of stilbene at the Si(100) surface the system was investigated by several spectroscopic methods such as UPS and NEXAFS.
In this work, we present density-functional theory (DFT) calculations of both stilbene isomers on Si14H28 clusters simulating the reconstructed Si(100) surface. Both isomers bind to Si with their central C=C double bond but differ in the arrangement of their phenyl rings with the overall binding being quite strong (binding energy of 3-4 eV). The obtained geometries have been used to calculate theoretical polarization-resolved C 1s NEXAFS spectra which are compared with recent experimental data and yield excellent agreement. This confirms the identification of both isomers for a further investigation of the isomerization process.
In addition, theoretical and experimental C 1s NEXAFS spectra of the free stilbene molecules are used to study adsorption induced changes in geometry and electronic structure.