Laser-induced target patterns in the oscillatory CO oxidation on Pt(110)

The formation of target patterns in oscillatory CO oxidation on Pt(110) is studied using the controlled creation of temperature heterogeneities on the catalyst surface induced by a focused laser beam. Outward and, for the first time, inward traveling target waves are observed as well as target patterns that are spatially confined to the immediate vicinity of the temperature inhomogeneity. The experimental results are compared to theoretical studies of the complex Ginzburg-Landau equation with a nonuniform frequency distribution and to numerical simulations of the Krischer-Eiswirth-Ertl model for the catalytic CO oxidation on Pt(110). Both the complex Ginzburg-Landau equation and the kinetic model need to be extended by a global coupling term to obtain good agreement with the whole range of experimental observations.