Regensburg 2002 – wissenschaftliches Programm
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O: Oberflächenphysik
O 13: Postersitzung (Adsorption an Oberfl
ächen, Elektronische Struktur, Magnetismus in reduzierten Dimensionen, Epitaxie und Wachstum, Halbleiteroberfl
ächen und -grenzfl
ächen, Organische Dünnschichten)
O 13.17: Poster
Montag, 11. März 2002, 18:00–21:00, Bereich C
Effect of Substrate Roughness on Triple-point Dewetting of Molecular Hydrogen — •Jörg Angrik, Masoud Sohaili, Jürgen Klier, and Paul Leiderer — Fakultät für Physik, Universität Konstanz, Postfach M676, D-78457 Konstanz
Triple-point dewetting is a well-known behaviour of molecular hydrogen and other noble gases on a solid substrate. This phenomenon always occurs at the bulk triple-point, T3, of the respective adsorbant. While theoretical calculations, under certain conditions, predict complete wetting even at temperatures below T3, up to now all experiments show dewetting. It is suspected that this is due to the roughness of the substrate. Obviously, adsorbed molecules exercise strains which are, in fact, induced due to the mismatch of the lattice constant of the substrate and the growing layers of the adsorbed materials. The micro-roughness of the substrate increases the strain of the adsorbed layers. This increased tension eventually leads to the growth of only a thin solid film at coexistence below T3. A recent theoretical effort associated with this work implies the dominating role of roughness on triple-point dewetting. Here we present different ways to achieve smoother surfaces and discuss the experimental results of the adsorption behaviour of solid hydrogen on substrates with different roughness.
This work is supported by the DFG under grant Le 315/20.