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Published Online May 6, 2004
Science DOI: 10.1126/science.1097513

Research Articles

Submitted on March 4, 2004
Accepted on April 21, 2004

Fluctuations and Bistabilities on Catalyst Nanoparticles

V. Johánek 1{dagger}, M. Laurin 1, A. W. Grant 2, B. Kasemo 2, C. R. Henry 3, J. Libuda 1*

1 Fritz-Haber-Institut der Max-Planck-Gesellschaft,Faradayweg 4-6, D-14195 Berlin, Germany.
2 Department of Applied Physics, Chalmers University of Technology, S-412 96, Göteborg, Sweden.
3 CMRCN-CNRS, Campus de Luminy, Case 913, F-13288 Marseille Cedex 9, France.

* To whom correspondence should be addressed.
J. Libuda , E-mail: libuda{at}fhi-berlin.mpg.de

{dagger}Present address: Institute for Surface and Interface Science, University of California, Irvine, CA 92697-2025, USA.

We show that coverage fluctuations on catalyst particles can drastically alter their macroscopic catalytic behavior. Scrutinizing the occurrence of kinetic bistabilities, it is demonstrated by molecular beam experiments on model catalysts that macroscopically observable bistabilities vanish completely with decreasing particle size, as previously predicted by theory. The effect is attributed to fluctuation-induced transitions between two kinetic reaction regimes, with a transition rate controlled by both particle size and surface defects. These results suggest that fluctuation-induced effects represent a general phenomenon affecting the reaction kinetics on nanostructured surfaces.


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