High-coverage structures of carbon monoxide adsorbed on Pt(111) studied by high-pressure scanning tunneling microscopy

High-pressure scanning tunneling microscopy was used to study the room-temperature adsorption of CO on a Pt(111) single-crystal surface in equilibrium with the gas phase. The coverage was found to vary continuously, and over the entire range from 10(-6)-760 Torr pressure-dependent moire patterns were observed, characteristic of a hexagonal or nearly hexagonal CO overlayer. Two different pressure ranges can be distinguished: below 10(-2) Tort, the moire lattice vector is oriented along a 30degrees high-symmetry direction of the substrate, corresponding to a pressure-dependent rotation of the CO overlayer with respect to the (1 x 1) Pt surface lattice, while above 10(-2) Torr, the CO layer angle is independent of the pressure. This behavior is analyzed in terms of the interplay of the repulsive CO-CO interaction potential and the substrate potential.


Published in:
Journal of Physical Chemistry B, 108, 38, 14497-14502
Year:
2004
ISSN:
1520-6106
ISBN:
1520-6106
Keywords:
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 Record created 2009-04-14, last modified 2018-12-03

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