Dissociation of water on oxygen-covered Rh{111}

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The adsorption of water and coadsorption with oxygen on Rh{111} under ultrahigh vacuum conditions was studied using synchrotron-based photoemission and photoabsorption spectroscopy. Water adsorbs intact on the clean surface at temperatures below 154 K. Irradiation with x-rays, however, induces fast dissociation and the formation of a mixed OH+H2O layer indicating that the partially dissociated layer is thermodynamically more stable. Coadsorption of water and oxygen at a coverage below 0.3 monolayers has a similar effect, leading to the formation of a hydrogen-bonded network of water and hydroxyl molecules at a ratio of 3:2. The partially dissociated layers are more stable than chemisorbed intact water with the maximum desorption temperatures up to 30 K higher. For higher oxygen coverage, up to 0.5 monolayers, water does not dissociate and an intact water species is observed above 160 K, which is characterized by an O 1s binding energy 0.6 eV higher than that of chemisorbed water and a high desorption temperature similar to the partially dissociated layer. The extra stabilization is most likely due to hydrogen bonds with atomic oxygen. (C) 2009 American Institute of Physics. [doi:10.1063/1.3266941]


  • A. Shavorskiy
  • T. Eralp
  • Evren Ataman
  • Cristina Isvoranu
  • Joachim Schnadt
  • Jesper N Andersen
  • G. Held
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Atom and Molecular Physics and Optics
Original languageEnglish
JournalJournal of Chemical Physics
Issue number21
Publication statusPublished - 2009
Publication categoryResearch