The coverage dependence of the local structure of C on Ni(100): a structural precursor to adsorbate-induced reconstruction

The local structure around adsorbed carbon atoms on Ni(100) has been determined by C 1s scanned-energy mode photoelectron diffraction both at low coverage (0.15 ML) and at 0.5 ML in the ‘clock’-reconstructed (2×2)p4g phase. At low coverage the C atoms occupy simple undistorted hollow sites; the radi...

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Bibliographic Details
Published in:Surface science 2000-02, Vol.446 (3), p.301-313
Main Authors: Terborg, R., Hoeft, J.T., Polcik, M., Lindsay, R., Schaff, O., Bradshaw, A.M., Toomes, R.L., Booth, N.A., Woodruff, D.P., Rotenberg, E., Denlinger, J.
Format: Article
Language:English
Subjects:
Adsorption and desorption kinetics
evaporation and condensation
Carbon
Chemisorption
Condensed matter: structure, mechanical and thermal properties
Exact sciences and technology
Nickel
Photoelectron diffraction
Physics
Solid surfaces and solid-solid interfaces
Solid-fluid interfaces
Surface reconstruction
Surface structure
Surface structure and topography
Surfaces and interfaces
thin films and whiskers (structure and nonelectronic properties)
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Summary:The local structure around adsorbed carbon atoms on Ni(100) has been determined by C 1s scanned-energy mode photoelectron diffraction both at low coverage (0.15 ML) and at 0.5 ML in the ‘clock’-reconstructed (2×2)p4g phase. At low coverage the C atoms occupy simple undistorted hollow sites; the radial strain of the Ni atoms surrounding the adsorbed carbon, proposed on the basis of STM images, is not found. The comparative study of the (2×2)p4g phase confirms the structural parameters of earlier studies, but allows direct comparison between the two phases free from systematic errors. The CNi near-neighbour distances to both top and second layer Ni atoms are unchanged by reconstruction, but the NiNi nearest-neighbour distance in the top layer increases significantly. This implies that the adsorbate-induced compressive stress is associated with NiNi, rather than NiC, repulsion as has previously been proposed. Special care has been taken to check for coupling of structural parameters in the analysis which might influence the precision of these comparisons, and a new methodology for identifying and assessing such parameter coupling is described.
ISSN:0039-6028
1879-2758
DOI:10.1016/S0039-6028(99)01159-0