Temporal Chaos and Spatio-Temporal Patterns in the Belousov-Zhabotinsky Reaction

Two sets of experiments on the Belousov-Zhabotinsky reaction are reported. In a well-stirred, open-flow reactor, results on the homogeneous reaction show that a prototypical route to an intermittent chaotic state agree well with many aspects of a one-dimensional normal form model for the subcritical period doubling bifurcation. These observations provide the first experimental observation of this form of intermittent behavior in the Belousov-Zhabotinsky reaction. Results from a second set of experiments in an open, spatially extended reaction-diffusion system are also reported. In a thin annular, radially fed hydrogel, the spontaneous appearance of traveling waves emanating from points called pacemakers is observed for many chemical conditions. Controlled perturbations applied to the pacemaker state are used to create an indefinitely stable, co-rotating wave state called the chemical pinwheel. This experiment reveals the first observation of complex spatio-temporal patterns associated with a spontaneous symmetry breaking in the co-rotating state.