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Spatio-temporal patterns in catalytic CO oxidation have been studied on a facetted Pt(1 1 0) surface in the 10 −5 mbar range using low energy electron microscopy (LEEM). Prior to the LEEM experiments the surface had been facetted by exposing the sample to reaction conditions in the 10 −4 mbar range. Irregularly shaped spiral waves, interacting oxygen fronts, travelling CO islands with slowly decaying trails and travelling wave fragments exhibiting a superimposed slow rotation have been found. The experimental results are discussed in terms of reversible facetting changing the anisotropy of the surface and adding a slow time scale to the dynamics of the reaction.

Using low-energy electron microscopy (LEEM), observations of periodic and slowly moving reaction diffusion fronts (RDFs) during the catalytic oxidation of CO on Pt(110) have enabled equivalent structures to be observed over a range of incident electron energies. Changes in contrast as a function of beam energy are interpreted in terms of inhibitor/activator concentration gradients as well as structural phase changes in the substrate.

Spatiotemporal pattern formation has been investigated with low energy electron microscopy (LEEM) and mirror electron microscopy (MEM) during the catalytic oxidation of CO on Pt{110} under both oscillatory and stationary conditions. Due to higher resolution and richer contrast than in previous PEEM studies, it has been possible to investigate the details of the nucleation and propagation of reaction–diffusion fronts which make up the patterns, Further, new and more complex patterns have been discovered which demonstrate the importance of both global coupling and reaction-induced roughening.