Reaction diffusion patterns in the catalytic CO‐oxidation on Pt(110): Front propagation and spiral waves

摘要: The dynamic behavior of elliptical front propagation and spiral‐shaped excitation concentration waves associated with the catalytic oxidation CO on a Pt(110)‐surface was investigated by means photoemission electron microscopy (PEEM). properties these patterns can be tuned through control parameters, viz., partial pressures O2 sample temperature. Over wide range parameters transition between two metastable states (COad Oad covered surface) proceeds via nucleation growth reaction‐diffusion (RD)‐fronts. Front velocities critical radii for are determined diffusion adsorbed under reaction conditions. If at constant pO2, T pressure is increased beyond value to qualitatively different takes place. fronts give way oxygen spiral spreading across CO‐covered areas. For fixed experimental conditions broad distribution spatial wavelengths temporal rotation periods found. This effect has attributed existence surface defects μm‐size which tip pinned. These data lead dispersion relation velocity wavelength, respectively, period. In addition, dynamics free influence externally modulated Now starts drift, resulting in distortion Archimedian shape pronounced Doppler effect.