Bayreuth 1998 – wissenschaftliches Programm
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SYB: Symposium Polymere und kleine Moleküle an Grenzflächen
SYB 2: Polymere und kleine Moleküle an Grenzflächen
SYB 2.2: Vortrag
Dienstag, 10. März 1998, 15:00–15:20, H18
Adsorption Mechanisms, Growth Regimes, and Their Modification for an Archetypal Self-Assembly System: Decanethiols on Au(111) — •F. Schreiber1, T.Y.B. Leung2, P. Fenter2, P. Eisenberger2, and G. Scoles2 — 1Max-Planck-Institut f"ur Metallforschung, Heisenbergstraße 1, D-70569 Stuttgart — 2Princeton Materials Institute, Princeton University, Princeton, NJ 08544
We present a multi-technique study of the growth processes and the phase diagram of decanethiol monolayers on Au(111). Through independent measurements of coverage, adsorption energy, and structure vs. growth rate and temperature, we provide a quantitative description of the molecular-level processes by which these aliphatic molecules self-assemble into highly ordered structures. We show that after initial fast formation of the low-density lying-down phase, the growth of the high-density standing-up phase proceeds with a ∼ 500 times slower rate. We explore the phase diagram and find the melting temperature to exhibit a striking coverage dependence with a value as high as 100 ∘C for full coverage. We point out important differences between equilibrium and non-equilibrium growth conditions. Finally, we discuss ways to modify the structure and the growth by pre-adsorption of surfactants. The results reveal a previously unknown complexity of the self-assembly of this widely used and intensively studied model system.