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

Paper SS2-TuA5
Effect of Oxygen on the Structure and Dissociation of Water on Ru(0001)

Tuesday, November 14, 2006, 3:20 pm, Room 2004

Session: Water-Surface Interactions on Metals
Presenter: A. Mugarza, Lawrence Berkeley National Laboratory and Institut de Ciencia de Materials de Barcelona, Spain
Authors: A. Mugarza, Lawrence Berkeley National Laboratory and Institut de Ciencia de Materials de Barcelona, Spain
T.K. Shimizu, Lawrence Berkeley National Laboratory
J. Cerda, Instituto de Ciencia de Materiales de Madrid CSIC, Spain
D.F. Ogletree, Lawrence Berkeley National Laboratory
M. Salmeron, Lawrence Berkeley National Laboratory
Correspondent: Click to Email
The adsorption and dissociation of water on Ru(0001) with 0.03 ML of pre-adsorbed O has been studied as a function of temperature by scanning tunneling microscopy. Below 140 K and at very low coverage (0.004 ML) water form complexes with O as well as dimer and trimer aggregates. At higher coverage (0.012ML) in this temperature range larger clusters with visible internal structure are observed. After annealing to 140 K, extended chain (worm-like) structures with enhanced contrast at the periphery are observed. By comparing the experimental images with theoretical calculations these structures have been attributed to mixtures of H@sub2@O and OH. The presence of O lowers the onset temperature for partial dissociation of water and affects the shape and internal structure of the clusters. In addition, atomic O reacts with the H on the surface to form OH. As the annealing temperature is raised to 220 K the worm-like structures disappear while, the concentration of H and OH increase, giving rise gradually to the formation of 2x2 O islands. These observations will be discussed and compared to the structures found on clean Ru(0001).