[Zurück]

A. Bukhtiyarov, K. Anic, Ch. Rameshan, H. Li, G. Rupprechter:
"Ir (100) CO and O2 induced reconstructions - a substrate material for model catalysts";
Poster: 12th Pannonian International Symposium on Catalysis, Castle Trest, Czech Republic; 16.09.2014 - 20.09.2014; in: "12th Pannonian International Symposium on Catalysis", (2014), S. 16.

Abstract:
Many {100} surfaces of fcc metals like Ir, Au or Pt reconstruct and form a corrugated hexagonal
surfaces. Thereby the hexagonal layer is lying in the hollow sites of the bulk substrate. This
reconstruction of the surface is highly sensitive towards adsorbed species and can be altered upon
adsorption of gases like CO, NO or O2. By controlling the experimental parameters of the film
preparation procedure we could prepare the (1x1) in a reducing environment, (5x1)
reconstruction in an oxidizing environment and a (2x1) oxygen ad layer structure. All structural
changes were followed by LEED.
The adsorption behavior of CO on each of the differently reconstructed surfaces was studied by
LEED, PM-IRAS and TPD. The infrared results reveal an on top geometry over a wide pressure
and temperature range.
The wavenumber of the C-O stretch vibration increases with increasing temperature on all three
reconstructions. With increasing CO background pressure the wavenumber of the C-O
stretch vibration increases steadily but then seems to converge towards a constant value on each
surface reconstruction.
The CO TPD reveals three distinct desorption peaks for the (1x1) and the (2x1)-O structures and
four peaks for the (5x1) reconstruction. Whereby in all three cases the low temperature species
evolve with increasing surface coverage.
Acknowledgement
This work was financially supported by the Austrian Science Fund (FWF) through Grant
Number: International Program I1041