Period Doubling and Spatiotemporal Chaos in Periodically Forced CO Oxidation on Pt(110)

Periodic forcing of chemical turbulence in the catalytic CO oxidation on Pt(110) can induce a period doubling cascade to chaos. Using a forcing frequency near the second harmonic of the system’s natural frequency, and carefully increasing the forcing amplitude, the system successively exhibits spiral wave turbulence, resonant pattern formation, and chaotic oscillations. In the latter case, global coupling induces strong spatial correlation. Experimental results are presented as well as numerical simulations using a realistic model. Good agreement is found between experiment and theory. The results give further insight into the complex nature of reaction-diffusion systems and are of high importance regarding control strategies on such systems. The presented setup enhances the range of achievable dynamical states and allows for new experimental investigations on the dynamics of extended oscillatory systems.

Figure 1

Mean Fourier spectra at different forcing amplitudes a: (a) 0, (b) 0.014, (c) 0.064, (d) 0.079, (e) 0.093.

Figure 2

Two-phase cluster pattern at $8:1$ entrainment. (a) Phase pattern, (b) amplitude pattern, (c) phase portrait, (d) phase histogram.

Figure 3

Simulated CO coverage for different entrainment states: (a) unforced, turbulent, (b) $4:1$ entrainment, (c) $8:1$ entrainment, (d) chaotic. Dark gray denotes low, light gray denotes high CO coverage.

Figure 4

Mean spatial cross correlation of unforced turbulence and forced chaotic oscillations. Results are given for experimental and numerical data.