Oxygen-induced wavefront instabilities and disorder in the Belousov–Zhabotinsky reaction

Wavefront instabilities leading to spatiotemporal disorder in a convection-free and horizontally homogeneous Ru(bpy)32+-catalyzed Belousov–Zhabotinsky reagent had previously been measured and simulated. Necessary conditions in a 20% O2 atmosphere (air) were: high light intensities (I>150 mW/m2) and low catalyst concentrations (⩽1 mM). Here, we show that at sufficiently high O2 concentrations, comparable instabilities and disorder appear even in the dark or at high (⩾1 mM) catalyst concentrations. In contrast, in the ferroin-catalyzed reagent such dynamic processes are not observed at any value of I in air, although they do occur — independently of I — at sufficiently high O2 concentrations.