Li-mediated feedback mechanism of oscillations in CO oxidation on a Rh field emitter tip

Observations of an isothermal oscillating motion of the reaction/diffusion front during CO-oxidation on [100]-oriented Rh field emitter tip are reported, Experiments were performed with the Lithium Field Desorption Microscope (Li-FDM) using 3 special imaging mode which allows an exclusive visualization of the reaction/diffusion front. Intentionally created Li-induced bistability in the Li-CO/O-Rh adsorption system as well as a Li-mediated feedback mechanism via Li-accelerated oxidation of the Rh surface and subsequent reduction of the stored oxygen by CO, are the prerequisites for the oscillating behavior of the reaction front.