The application of photoemission microscopy to the study of heterogeneous reactions over metal single crystal surfaces

The development of UHV instrumentation for photoemission electron microscopy (PEEM) has opened up the possibility of investigating in situ the morphology of metal single crystal surfaces during simple catalytical reactions in the pressure range up to 10^–4 mbar. We have studied the Pt(100) surface during the transition from the high to low rate branches of the CO oxidation reaction. Steps, step bunches and grain boundaries have been identified. They play an important role in the decomposition of CO and the deposition of carbon and probably regulate the reactivity of the Pt surface.