Spirals and chemical turbulence in an excitable surface reaction

Rigidly rotating spiral waves under constant external parameters, drifting spirals under the influence of a periodic perturbation as well as turbulent patterns have been observed in the isothermal CO oxidation on a Pt(1 1 0) single crystal surface. A simple reaction-diffusion model can reproduce these findings. It is pointed out that the spiral resonances depend on the symmetry of the surface. The mechanism leading to turbulence is briefly described.