The displacement of hydrogen by carbon monoxide on the (100) face of tungsten: A photoemission and thermal desorption study
T. V. Vorburger, D. R. Sandstrom and B. J. Waclawski
Surface Science. 60, 211-230 (1976)
Abstract:
Photoelectron spectra (hv = 21.22 eV) and thermal desorption data were obtained for CO
and H coadsorbed on W(100) at 80 K. When the clean surface is exposed to a saturation dose of H2, subsequent
exposure to CO results in the formation of a state whose emission spectrum is similar to that of molecular -CO.
Upon heating to ∼280 K, a structural rearrangement occurs in which most of the adsorbed CO is converted to the
strongly bound form as the hydrogen is simultaneously desorbed. These data plus the observation that H2 cannot
be adsorbed to any significant degree on a saturated layer of -CO suggest that adsorbed -CO and H occupy the same
atomic sites on the W(100) surface. The distinction between long and short range repulsive CO---H interactions is
discussed. For CO adsorbed on clean W(100), the range of activation energies for vigin to conversion is calculated
from the UPS data to be 45-62 kJ/mol.
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