Berlin 2005 – wissenschaftliches Programm

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O: Oberflächenphysik

O 36: Postersitzung (Elektronische Struktur, Grenzfl
äche fest-flüssig, Halbleiteroberfl
ächen und -grenzfl
ächen, Nanostrukturen, Oberfl
ächenreaktionen, Teilchen und Cluster, Struktur und Dynamik reiner Oberfl
ächen)

O 36.65: Poster

Montag, 7. März 2005, 15:00–18:00, Poster TU F

Pressure Gap in Ammonia Oxidation on Platinum — •Sebastian Günther¹, Axel Scheibe², Axel Knop-Gericke³, Yingfeng Zeng², and Ronald Imbihl² — ¹Department Chemie, Ludwig-Maximilians-Universität München — ²Institut für Physikalische Chemie und Elektrochemie, Universität Hannover — ³Fritz-Haber-Institut der MPG

In an attempt to bridge the pressure gap in ammonia oxidation on platinum, in situ X-ray photoelectron spectroscopy (XPS) was used to follow the adsorbate coverage on Pt(533) in the 10⁻⁴ mbar range and at about 1 mbar. The N 1s regimes show that at 100 - 300 ^∘ C NH_x species are presented; at high temperature atomic nitrogen is dominant, adsorbed NO decompose already below T = 80 ^∘ C. The results are compared with the simulations of a realistic mathematical model. For bridging the material gap kinetic studies of N₂ and NO formation on Pt(533) are compared with measurements on a polycrystalline Pt foil. The overall kinetics are very similar, but pronounced differences exist with respect to the hysteretic behavior.