Dissociation of water on oxygen-covered Rh{111}

Summary, in English

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]

• Author: A. Shavorskiy; T. Eralp; Evren Ataman; Cristina Isvoranu; Joachim Schnadt; Jesper N Andersen; G. Held
• Department/s: Synchrotron Radiation Research
• Publishing year: 2009
• Language: English
• Publication/Series: Journal of Chemical Physics
• Volume: 131
• Issue: 21
• Links: http://dx.doi.org/10.1063/1.3266941
• Document type: Journal article
• Publisher: American Institute of Physics (AIP)
• Topic: Atom and Molecular Physics and Optics
• Status: Published
• ISBN/ISSN/Other: ISSN: 0021-9606