Regensburg 2004 – wissenschaftliches Programm

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O: Oberflächenphysik

O 20: Oberflächenreaktionen I

O 20.3: Vortrag

Dienstag, 9. März 2004, 11:45–12:00, H45

Adsorption and Interaction of Ethylene on stoichiometric and oxygen rich RuO2(110) — •Ursula A. Paulus1, Yuemin Wang1, Hans P. Bonzel2, Karl Jacobi1, and Gerhard Ertl11Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, D-14195 Berlin — 2Forschungszentrum Jülich, ISG3, D-52425 Jülich

The nature of the oxygen species responsible for ethylene (C2H4) oxidation on Ag particles is still under discussion. Here we prepare stoichiometric and oxygen rich RuO2(110) surfaces exposing either coordinatively unsaturated Ru (Ru-cus) and oxygen (O-bridge) atoms or O-bridge and O-cus atoms. We study the adsorption and interaction of C2H4 on those surfaces applying high-resolution electron energy loss spectroscopy (HREELS) and thermal desorption spectroscopy (TDS).

Under the applied conditions (ultra-high vacuum, no continuous reactant supply) C2H4 adsorbs molecularly on the stoichiometric RuO2(110) surface at 85 K and desorbs again molecularly at 320 K. Warming up the sample to 260 K leads to changes in the bond strength. A rearrangement from π-bonded to σ-bonded is suggested.

On the oxygen rich RuO2(110) surface a complete oxidation of C2H4 to CO2 and water is observed. Warming up the sample between 85 K and 500 K HREEL spectra indicate the presence of several reaction intermediates, which are discussed here.

[1] J. Wang et al., J. Phys. Chem. B. 106 (2002) 3422.

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