OSCILLATIONS OF THE CO OXIDATION ON RH INDUCED BY FIELD-CONTROLLED LICOADSORPTION

The first observations of isothermal oscillating motion of the reactio n/diffusion front during CO oxidation on a Rh field emitter tip are re ported. Experiments were performed with a new lithium field desorption microscope (Li-FDM), using a special imaging mode which permits exclu sive viewing of the reaction/diffusion front. The observed oscillation s are generated by an artificial shift in the oxygen and CO adsorption /desorption kinetics caused by field-controlled selective Li coadsorpt ion on a selected area of the Rh field emitter tip. In this way an exa mple of the control of the adsorption properties of a surface on the a tomic scale is demonstrated.