Spiral Wave Dynamics as a Function of Proton Concentration in the Ferroin-Catalyzed Belousov-Zhabotinskii Reaction

Article abstract of DOI:10.1021/j100382a036

The dependence of the geometry and dynamics of spiral waves on the excitability of the ferroin-catalyzed Belousov-Zhabotinskii reaction was investigated in detail by computerized high-resolution spectrophotometry.Many time series of digital images were recorded by using solution layers prepared with different sulfuric acid concentrations (0.15 -0.70 M), which control the excitability of the medium through the resulting H⁺ concentration.While spirals generated in highly excitable media (high acidity) are almost Archimedian, there are pronounced deviations from this geometry with decreasing excitability (low acidity).The motion of the tip of regular spirals proceeds in a circle around a spatially stable rotation center, but in systems of low excitability it performs several loops.This compound motion often resembles a prolate epicycloid.During each loop there exists a well-defined temporary center reminiscent of that found in regular spiral rotation.The distorted spiral geometries are described quantitatively, and data for the average ferriin concentration, wave amplitude, and maximum gradients are given as a function of proton concentration.With decreasing +> the wave amplitude and maximum ferriin gradient increase and the average ferriin concentration decreases.These functional dependencies are smooth, and no evidence for a qualitative transition is found in the investigated +> range.