Photoinduced Oscillations and Pulse Waves in the Hydrogen Peroxide-Sulfite-Ferrocyanide Reaction.

The hydrogen peroxide-sulfite-ferrocyanide reaction shows excellent photosensitivity under pulse light illumination, which can be used to efficiently control the spatiotemporal dynamics of the nonlinear chemical system. Here, we numerically simulated the photoinduced pH oscillations by integrating two models that describe the oscillatory and photosensitive behaviors, respectively. A dynamic transition from the low-pH steady state to oscillations can be obtained using light illumination. In accordance with the simulation results, oscillatory dynamics was experimentally obtained under light illumination through excitation of a low-pH steady state. In the reaction-diffusion medium, corresponding multiple pulse waves were observed under suitable acid concentration and illumination conditions. Hence, light illumination can be efficiently employed to tune pattern formation in pH dynamic systems. Especially, the observation indicates that the local oscillations and pulse waves were promoted by diffusion in the gel reactor when comparing with dynamics in a homogeneous system.