Hamburg 2001 – wissenschaftliches Programm
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O: Oberflächenphysik
O 9: Organische Dünnschichten und Festkörper
O 9.10: Vortrag
Montag, 26. März 2001, 18:30–18:45, B
Thioaromatic self-assembled monolayers on gold and silver substrates — •Michael Zharnikov1, Stefan Frey1, Völker Stadler1, Karin Heister1, Wolfgang Eck1, Björn Zeysing2, Andreas Terfort2, and Michael Grunze1 — 1Angewandte Physikalische Chemie, Universität Heidelberg, Im Neuenheimer Feld 253, 69120 Heidelberg — 2Anorganische und Angewandte Chemie, Universität Hamburg, 20146 Hamburg
Self-assembled monolayers (SAMs) formed from thiophenol, p-biphenylthiol, p-terphenylthiol, and anthracenethiol on polycrystalline Au and Ag were characterized by X-ray photoelectron spectroscopy and angle resolved near edge X-ray absorption fine structure spectroscopy. With the exception of the poorly defined thiophenol film on Au, all thioaromatic molecules were found to form highly-oriented and densely packed SAMs on both substrates. The molecular orientation and orientational order of the adsorbed thioaromatic molecules depends on the number of aromatic rings, the substrate and the rigidity of the aromatic system. The molecules, which in average are slightly inclined with respect to the surface normal, show a less tilted orientation with increasing length of the aromatic chain, and as observed for aliphatic SAMs, they exhibit smaller tilt angles on Ag than on Au. However, the difference in the tilt angles for aromatic SAMs on Au and Ag is smaller than observed in the aliphatic films. A comparison of the monolayers formed from p-terphenylthiol and anthracenethiol films suggests that a higher molecular rigidity has only a slight effect on the final molecular orientation within the respective SAMs.