Metastable impact electron emission microscopy of the catalytic H2 oxidation on Rh(1 1 0)

Laterally resolved metastable impact electron spectroscopy is based on the energy analysis of electrons originating from collisions of metastable He* (23S) atoms with the surface, and can be used for probing the spatial distribution of surface species, i.e. for chemically resolved surface microscopy (MIEEM=metastable impact electron emission microscopy). We report upon first MIEEM results on the spectroscopic imaging of the catalytic H2 oxidation on the clean and potassium-precovered Rh(1 1 0) surface, in which the spatio-temporal distribution of the reactants on the surface, the reaction fronts as well as the redistribution of the initially spatially homogeneous K coverage have been monitored. The results are in agreement with data previously obtained by scanning photoelectron microscopy and are discussed in terms of self-organization in the diffusion zone.