IUVSTA 15th International Vacuum Congress (IVC-15), AVS 48th International Symposium (AVS-48), 11th International Conference on Solid Surfaces (ICSS-11)
    Surface Science Wednesday Sessions
       Session SS2-WeM

Invited Paper SS2-WeM3
Dynamic Spatial Patterns in a Surface Reaction - The Microscopic and Mesoscopic Scales

Wednesday, October 31, 2001, 9:00 am, Room 121

Session: Surface Reactions on Metals
Presenter: J. Wintterlin, Fritz-Haber-Institut, Germany
Authors: J. Wintterlin, Fritz-Haber-Institut, Germany
C. Sachs, Fritz-Haber-Institut, Germany
M. Hildebrand, Fritz-Haber-Institut, Germany
S. Voelkening, Fritz-Haber-Institut, Germany
G. Ertl, Fritz-Haber-Institut, Germany
Correspondent: Click to Email
One of the most spectacular observations in surface catalytic reactions is the formation of dynamic spatial patterns that are connected with non-linear terms in the reaction kinetics. We have investigated such phenomena, both on the atomic and the mesoscopic scales, for the catalytic water formation from adsorbed oxygen and hydrogen on a Pt(111) surface. By means of scanning tunneling microscopy (STM) propagating reaction fronts were observed on a 10 to 1000 nm scale. Simulations were performed with a reaction diffusion model that contains an autocatalytic reaction sequence. The model predicts reaction fronts, formed by travelling interfaces between adsorbed oxygen and water. The fronts contain the reaction intermediate OH, in full qualitative agreement with the experiment. However, quantitative simulations reveal deviations from the experiment, demonstrating the limitations of this description. The atomic scale processes in the fronts, which were resolved by STM, indicate that the reasons for these deviations lie in the simplifications of standard reaction-diffusion models, namely the assumptions of a random occupation of adsorption sites and of spatially independent kinetic constants.