Abstract
The reaction of water has been investigated on the surfaces of stoichiometric and oxygen defected UO2(1 1 1) single crystal. On the stoichiometric surface most of the adsorption of H2O molecules at 300 K is reversible (>80%). The remaining water on the surface desorbs in two TPD peaks at 400 and 530 K with no evidence for H-2 formation. On the contrary on Ar+-sputtered surfaces, water is strongly adsorbed. The Ar+-sputtered surfaces contained large amounts of U metal or U cations in lower oxidation state than +4 (a shoulder at BE approximate to 377 eV). Upon H2O adsorption at room temperature most of the shoulder at 377 eV has disappeared suggesting a dissociative adsorption of water molecules. Further evidence of water dissociation was given by H-2 desorption during TPD. The amount of desorbed H-2 tracked the extent of surface reduction. A complex set of H-2 desorption (three peaks) was seen during TPD. These peaks were both sensitive to prior surface reduction and surface coverage. (C) 2004 Elsevier B.V. All rights reserved.
Original language | English |
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Pages (from-to) | 135-144 |
Number of pages | 10 |
Journal | Surface Science |
Volume | 563 |
Issue number | 1-3 |
Early online date | 26 Jun 2004 |
DOIs | |
Publication status | Published - 10 Aug 2004 |
Keywords
- atom-solid interactions
- electron-solid interactions
- Auger electron spectroscopy
- low energy electron diffraction (LEED)
- X-ray photoelectron spectroscopy
- thermal desorption
- water
- uranium oxide
- ray photoelectron-spectroscopy
- uranium oxides
- vapor
- polycrystalline
- adsorption
- acid