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

Paper SS2-TuA7
Wetting and Multilayer Growth on Metal Surfaces

Tuesday, November 14, 2006, 4:00 pm, Room 2004

Session: Water-Surface Interactions on Metals
Presenter: A. Hodgson, The University of Liverpool, UK
Authors: A. Hodgson, The University of Liverpool, UK
G. Zimbitas, The University of Liverpool, UK
M. Gallagher, The University of Liverpool, UK
S. Haq, The University of Liverpool, UK
G.R. Darling, The University of Liverpool, UK
Correspondent: Click to Email
We describe the wetting behaviour of water ice films on Ru(0001) and Pt(111) and how this is modified by OH co-adsorption. Both metals will form an intact water monolayer, but with different structures and wetting behaviour. Water forms a labile wetting layer on Pt(111), with hexagonal @sr@37 and @sr@39 ice structures at increasing coverage. Multilayer adsorption forms clusters whose size and registry to the @sr@39 layer depends on thickness and preparation conditions, thick ice films forming an oriented incommensurate crystalline ice, stabilised by reconstruction of the interface layer. OH co-adsorption pins the wetting layer into registry with Pt, forming an ordered (OH+H@sub 2@O) phase which can not restructure in response to multilayer adsorption. Although this layer has a similar OH@sub x@ skeleton to ice Ih, water does not form a stable 2D wetting layer and the surface is hydrophobic. On Ru(0001) the strong water-metal interaction pins the first monolayer into a structure that is unfavourable for hydrogen-bonding to a multilayer ice film. This layer does not wet, even for thick films, instead thick 3D multilayer ice clusters form which minimise their contact to the water monolayer. No ordered multilayer ice structure is formed, indicating that the tightly bound wetting layer does not reconstruct to accommodate the incommensurate ice Ih(0001) film to the metal surface. The factors influencing multilayer adsorption are examined using DFT calculations to compare adsorption on top of different water and (OH+H@sub 2@O) structures. We argue that wetting is determined by the ability of the first layer to restructure to optimise the bonding between a bulk ice layer and the metal surface.