Interaction of H2O with a clean and oxygen precovered Ni(110) surface studied by XPS |
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Authors: | C Benndorf C Nöbl F Thieme |
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Institution: | Institut für Physikalische Chemie, Universität Hamburg, Laufgraben 24, D-2000 Hamburg 13, Fed. Rep. of Germany |
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Abstract: | The adsorption and reaction of H2O on clean and oxygen precovered Ni(110) surfaces was studied by XPS from 100 to 520 K. At low temperature (T<150 K), a multilayer adsorption of H2O on the clean surface with nearly constant sticking coefficient was observed. The O 1s binding energy shifted with coverage from 533.5 to 534.4 eV. H2O adsorption on an oxygen precovered Ni(110) surface in the temperature range from 150 to 300 K leads to an O 1s double peak with maxima at 531.0 and 532.6 eV for T=150 K (530.8 and 532.8 eV at 300 K), proposed to be due to hydrogen bonded Oads… HOH species on the surface. For T>350 K, only one sharp peak at 530.0 eV binding energy was detected, due to a dissociation of H2O into Oads and H2. The s-shaped O 1s intensity-exposure curves are discussed on the basis of an autocatalytic process with a temperature dependent precursor state. |
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