Article,
High-Coverage Structures of Carbon Monoxide Adsorbed on Pt(111) Studied by High-Pressure Scanning Tunneling Microscopy�
J. Phys. Chem. B, (2004)
DOI: 10.1021/jp0492218
Abstract
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 Torr, the moire� lattice vector is oriented along a 30� high-symmetry
direction of the substrate,
corresponding to a pressure-dependent rotation of the CO overlayer
with respect to the (1 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.
