AVS 53rd International Symposium
    Surface Science Tuesday Sessions
       Session SS2-TuA

Paper SS2-TuA6
The True Ground State of Water Adlayers on Ru(0001)

Tuesday, November 14, 2006, 3:40 pm, Room 2004

Session: Water-Surface Interactions on Metals
Presenter: C. Wöll, Ruhr-Universitat Bochum, Germany
Authors: F. Traeger, Ruhr-Universitat Bochum, Germany
D. Langenberg, Ruhr-Universitat Bochum, Germany
C. Wöll, Ruhr-Universitat Bochum, Germany
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Recently the structure of water adlayers adsorbed on Ru(0001) has given rise to a pronounced controversy.@footnote 1-5@ One reason for the ongoing debate are experimental problems arising from the fact that H2O-adlayers on this surface exhibit a very low threshold for electron beam damage. Here we present the first results on the structure of water (D2O) adlayers on Ru obtained with a method where electron beam damage (either through primary or secondary electrons) can be strictly excluded. Results from He-atom scattering (HAS) reveal that the true ground-state of water on this surface exhibits a high-order commensurate structure. The HAS diffraction patterns are not consistent with any of the previous structural models proposed for this adsorbate system, either on the basis of experimental results or theoretical investigations. Test experiments revealed that the water adsorbate is indeed very sensitive to electrons, even short exposure times in front of the LEED instrument led to the formation of the well-known (R3xR3)R30° structure.@footnote 1@ HAS measurements also demonstrate that electron irradiation results in both, electron induced desorption and electron-induced dissociation. We have developed an optimized preparation procedure for high-quality water adlayers, which is somewhat different from the previously proposed procedure. Structural models for the true ground state of water on the Ru(0001)-surface will be presented in the talk. @FootnoteText@ @footnote 1@ G. Held and D. Menzel, Surf. Sci. 316, 92, (1994).@footnote 2@ P. J. Feibelman, Science 295, 99, (2002).@footnote 3@ C. Clay, S. Haq and A. Hodgson, Chem. Phys. Lett. 388, 89, (2004).@footnote 4@ K. Andersson et al., Phys. Rev. Lett. 93, 196101-1, (2004).@footnote 5@ J. Weissenrieder et al., Phys. Rev. Lett. 93, 196102-1, (2004) .