CO adsorption on Pt(1 1 0) investigated by X-ray photoelectron diffraction

• Published in: Surface science 2001-05, Vol.478 (3), p.180-192
• Main Authors: Nowicki, M., Emundts, A., Pirug, G., Bonzel, H.P.
• Format: Article
• Language: English
• Subjects: Carbon monoxide; Chemistry; Exact sciences and technology; General and physical chemistry; Low energy electron diffraction (LEED); Low index single crystal surfaces; Photoelectron diffraction; Platinum; Solid-gas interface; Solid–gas interfaces; Surface physical chemistry; X-ray photoelectron spectroscopy
• ISSN: 0039-6028; 1879-2758
• DOI: 10.1016/S0039-6028(01)00890-1

The adsorption of CO on a Pt(1 1 0) surface was studied by X-ray photoelectron spectroscopy (XPS), X-ray photoelectron diffraction (XPD), and low energy electron diffraction (LEED). CO exposure during cooling the sample from 600 K to several final temperatures, T f, resulted in CO layers of increasing coverage. For T f>350 K, a disordered CO layer was obtained, characterized by a (1×1) LEED pattern, but also by an increasing intensity of inter-molecular scattering peaks in C 1s XPD with increasing CO coverage. This behavior appears to indicate a rising degree of short range order in the adlayer. A well-ordered (2×1)-CO pattern at a coverage of 1.0 was obtained for final temperatures below 300 K. XPD measurements provided evidence of 22° tilted CO molecules, with the projected tilt parallel to the [0 0 1] azimuth of the Pt(1 1 0) surface. The latter is consistent with a p2mg symmetry of the (2×1)-CO structure. A second well-ordered c(8×4)-CO pattern was prepared upon adsorption at T