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O: Oberflächenphysik

O 30: Adsorption an Oberfl
ächen III

O 30.1: Talk

Monday, March 7, 2005, 10:45–11:00, TU EB301

Fully polarization resolved near edge x-ray absorption fine structure spectroscopy of hydrocarbons adsorbed on Si(001)-(2x1) — •Franz Hennies¹, Alexander Föhlisch¹, Annette Pietzsch¹, Mitusuru Nagasono¹, Nadine Wittkowski², Stina Matsson³, Maria-Novella Piancastelli³ und Wilfried Wurth¹ — ¹Universität Hamburg, Institut für Experimentalphysik, Luruper Chaussee 149, D-22761Hamburg — ²Laboratoire d’ Optique des Solides, — ³Department of Physics, Uppsala University, Sweden

The adsorption of simple hydrocarbons on Si(001) has been used as a model system for the Si-C interaction and as such been focus of investigations for more than 20 years. Nevertheless the exact geometrical configuration and the symmetry of the electronic states of several of the investigated adsorbates are still under debate.

We present a fully polarization resolved near edge x-ray absorption fine structure spectroscopy (NEXAFS) study of the adsorption of ethylene, benzene and acetylene on the single domain Si(001)-(2x1) surface which was performed at MAXLab in Lund, Sweden. We give direct experimental proof for ethylene adsorbing in a rotated, so called "dimerized"structure [1]. For benzene, the "butterfly"adsorption model is correct [2]. Acetylene adsorbs at room temperature in more than one configuration [3]. This work has been supported by DFG Fo343/1-1.

[1] F. Hennies, A. Föhlisch et al., Surf. Sci. 529, 144 (2003)

[2] N. Witkowski, F. Hennies et al., Phys. Rev. B 68, 115408 (2003)

[3] A. Pietzsch, F. Hennies et al., Surf. Sci. 562, 65 (2004)