High resolution electron-energy-loss spectroscopy of vibrational states of absorbates on (111) tungsten

Electron-energy-loss spectra are reported for adsorbed species on a (111) tungsten surface following exposure to gaseous H 2, D 2 and C 2H 2 at 300 K. Vibrational frequencies are resolved which are characteristic of the chemical and surface structural nature of the adsorbates. Dissociative chemisorp...

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Bibliographic Details
Published in:Surface science 1977, Vol.63, p.193-202
Main Authors: Backx, C, Feuerbacher, B, Fitton, B, Willis, R.F
Format: Article
Language:English
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Summary:Electron-energy-loss spectra are reported for adsorbed species on a (111) tungsten surface following exposure to gaseous H 2, D 2 and C 2H 2 at 300 K. Vibrational frequencies are resolved which are characteristic of the chemical and surface structural nature of the adsorbates. Dissociative chemisorption occurs in all cases at low coverage (⪅1 L exposure). At high coverages, acetylene shows complex coverage-dependent chemisorption behaviour. A transition from dissociative to molecular chemisorption occurs in the range 2 to 4 L exposure with corresponding spectral and work function changes. Fundamental, overtone and combination frequencies are resolved, which serve to identify a single surface molecular complex at high coverage. A comparison of the results with the vibrational excitation energies of free molecules indicates a high-coverage surface molecular complex in which significant rehybridization of the C atom has occurred.
ISSN:0039-6028
1879-2758
DOI:10.1016/0039-6028(77)90338-7