CO dissociation on Mo(1 1 0) studied by high-resolution core-level spectroscopy

• Published in: Surface science 2001-10, Vol.492 (1), p.185-194
• Main Authors: Jaworowski, A.J, Smedh, M, Borg, M, Sandell, A, Beutler, A, Sorensen, S.L, Lundgren, E, Andersen, J.N
• Format: Article
• Language: English
• Subjects: Carbon monoxide; Chemistry; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; General and physical chemistry; Molecule–solid reactions; Molybdenum; Photoelectron spectroscopy; Physics; Solid-fluid interfaces; Solid-gas interface; Surface physical chemistry; Surfaces and interfaces; thin films and whiskers (structure and nonelectronic properties)
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(01)01447-9

We have studied the CO/Mo(1 1 0) adsorption system at different sample temperatures by high-resolution core-level spectroscopy and near-edge X-ray-absorption fine-structure measurements. We demonstrate that CO molecules having different tilt angles with respect to the surface normal may be assigned to different components of the C 1s core-level spectra. The tilt of the CO molecules is shown to depend on the CO coverage. The thermally induced dissociation of CO is studied and is shown to differ at low and high initial CO coverages. At low coverage CO dissociation starts already at temperatures as low as 125 K whereas at saturation CO coverage no dissociation occurs below 280 K. The reasons for this difference in dissociation behavior are discussed and it is concluded that steric effects play a large role.