CO adsorption on the Pt/Rh(100) surface studied by high-resolution photoemission

• Published in: Surface science 2000-06, Vol.458 (1), p.135-146
• Main Authors: Ramstad, A., Strisland, F., Ramsvik, T., Borg, A.
• Format: Article
• Language: English
• Subjects: Adsorption and desorption kinetics; evaporation and condensation; Carbon monoxide; Chemisorption; Chemistry; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; General and physical chemistry; Growth; Low index single crystal surfaces; Metallic films; Physics; Platinum; Rhodium; Solid-fluid interfaces; Solid-gas interface; Surface physical chemistry; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties); Synchrotron radiation photoelectron spectroscopy
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(00)00430-1

Submonolayers of platinum have been deposited on an Rh(100) substrate. Platinum growth and subsequent CO adsorption on the bimetallic surface has been studied by high-resolution photoemission applying synchrotron radiation. Platinum was found to grow as small, single-layer islands on Rh(100). The CO adsorption site on both metals is very sensitive to compositional changes in the bimetallic surface. A site switch from on-top to bridge sites in the c(2×2) CO overlayer on Rh(100) has been observed in the presence of 0.2 monolayers (ML) of platinum. The CO saturation coverage is found to decrease dramatically with increasing platinum coverages. 0.9 ML of platinum on Rh(100) binds approximately half the CO bound by Pt(100). We explain this in terms of a reduced COPt bond strength through a ‘ligand effect’.