Hamburg 2001 – scientific programme

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O: Oberflächenphysik

O 30: Oberfl
ächenreaktionen (III)

O 30.10: Talk

Thursday, March 29, 2001, 12:45–13:00, K

Dissociative chemisorption of O₂ on Al(111): an abstraction reaction — •Marcello Binetti, Olaf Weiße, and Eckart Hasselbrink — Inst. für Phys. Chemie, FB Chemie, Universität Essen, Universitätsstr. 5, D-45117 Essen, Deutschland

The dissociative chemisorption of O₂ on Al(111) is an intriguing reaction for different reasons: in despite of its high exothermicity, it is an activated reaction;[1] the chemisorption of thermal O₂ molecules, mainly results in single O-atoms chemisorbed on the exposed surface.[2] We have studied this process using a supersonic molecular beam. Oxygen atoms resulting from the abstraction channel are detected by REMPI spectrometry. The detected O-atoms constitute a direct proof that abstraction reactions are a common pathway during the initial stage of aluminum oxidation, for a wide range of translational energies (90-450 meV).[3] The abstraction efficiency shows a strong dependency on both the translational energy and the rotational energy of the incoming molecules. Our results corroborate the work by Andew J. Komrowski and Andrew C. Kummel at the University of California in San Diego, who studied this process using an STM coupled to a molecular beam.

[1] L. Österlund, I. Zoric and B. Kasemo, Phys. Rev. B 55, 15452 (1997).

[2] H. Brune, J. Wintterlin, R. J. Behm and G. Ertl, Phys. Rev. Lett. 68, 624 (1992).

[3] M. Binetti, O.Weiße, E. Hasselbrink, A. J. Komrowski and A. C. Kummel, Faraday Disc. Chem. Soc. 117 (2000).