Dresden 2011 – wissenschaftliches Programm
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O: Fachverband Oberflächenphysik
O 19: Metal substrates: Adsorption of O / H and inorganic molecules II
O 19.4: Vortrag
Montag, 14. März 2011, 18:00–18:15, WIL A317
Constructing the Wetting Layer of H2O on Pt(111) — •Sebastian Standop1, Georgia Lewes-Malandrakis1, Markus Morgenstern2, Thomas Michely1, and Carsten Busse1 — 1II. Physikalisches Insitut, Universität zu Köln, Zülpicher Straße 77, D-50937 Köln — 2II. Physikalisches Institut (IIB), RWTH Aachen, D-52056 Aachen
Adsorption of water molecules on Pt(111) leads to a number of complex superstructures in accordance with scattering experiments. A common and prominent feature of these layers are triangular shaped depressions. On the basis of density functional theory calculation these depressions were predicted to contain flat water molecule hexamers [1].
Through co-adsorption experiments with Xe and CO molecules and artificial manipulation using Scanning Tunneling Microscopy (STM) we directly show that the triangular depressions are indeed hexamers of flat lying water molecules rotated by about 30∘ with respect to the surrounding host structure of water molecules [2]. Under appropriate STM imaging conditions these hexamers act as nuclei for the growth of the √3 × √3 R30∘ water wetting layer, known to result from electron exposure in LEED experiments. Our observations explain how it is possible for the wetting layer to transform rapidly into this structure. Using graphene flakes grown by ethylene decomposition, we directly compare binding and structure of wetting layers on Pt(111) and on grapheme using thermal desorption spectroscopy and STM.
[1] S. Nie et al., PRL 105 (2010) 026102, [2] S. Standop et al., PRB 82 (2010) 161412(R)