Self-organizing reactions on surfaces

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Abstract
During heterogeneous catalytic reactions the involved reactants adsorbed on a surface may exhibit phenomena of intrinsic spatial and temporal self-organization, when the processes take place far from thermodynamic equilibrium. Adsorption of atoms or molecules has a measurable effect on the work function. By means of the photo emission electron microscope (PEEM) it is possible to image the local distributions of the adsorbed species in real time. The wide range of PEEM observations during nonlinear surface reactions will be discussed here. In particular, new results are presented including spatio-temporal pattern formation associated with the oscillatory catalytic CO oxidation on PT(100)-, Pt(110)-single and polycrystalline surfaces. The different patterns, like solitary waves exhibiting soliton-like behavior, spirals and target patterns, will be discussed. These features are connected with the state of excitability, while in the oscillatory region of the reaction standing waves and chaos can be observed.