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O: Oberflächenphysik
O 28: Adsorption an Oberfl
ächen III
O 28.2: Vortrag
Donnerstag, 27. März 2003, 11:30–11:45, FOE/ANOR
Coadsorption of CO and D2O on Pt(111) studied by in-situ high resolution photoemission — •Martin Kinne, Thomas Fuhrmann, Barbara Tränkenschuh, Junfa Zhu, Reinhard Denecke, and Hans-Peter Steinrück — Physikalische Chemie II, Universität Erlangen-Nürnberg, 91058 Erlangen
High-resolution X-ray photoelectron spectroscopy has been used to study the coadsorption of D2O with CO on the Pt(111) surface. In the absence of D2O carbon monoxide adsorbs on linear (on-top) and two-fold (bridge) coordinated sites; hereby the on-top site is energetically favoured compared to the latter, leading to a preferred adsorption on on-top sites for coverages below 0.5 ML, as recently confirmed [1]. The presence of a bilayer of D2O on the surface changes the adsorption behaviour significantly: in accord with literature [2] our studies show that in this case the bridge site is occupied first and is followed by on-top site adsorption. This process is found to be reversible, as temperature programmed XPS shows a site exchange of CO during desorption of D2O at ∼150 K. The site exchange can also be induced by dosing D2O on a surface precovered with 0.2 ML CO. By using a supersonic molecular beam as a doser for CO, supplying a constant pressure during uptake, we also studied the CO adsorption kinetics on a D2O precovered surface. Furthermore, the coadsorbate effect on the C1s and O1s electronic binding energies as well as on the desorption kinetics of D2O is being discussed. (Supported by DFG, Project Ste620/4-1)
[1] Kinne et al., J. Chem. Phys. 117 (2002) 10852
[2] Kizhakevariam et al., J. Chem. Phys. 100 (1994) 6750