Effect of oxygen on wave propagation in the ferroin-catalysed Belousov–Zhabotinsky reaction

Abstract

An experimental investigation of the propagation of reaction-diffusion waves in thin layers of solution for the ferroin-catalysed Belousov–Zhabotinsky reaction is reported. It is shown that for layers of 1.5 mm or greater depth, there are no significant effects of oxygen on the wave speed, but that for more shallow layers the waves are sensitive to the presence of O₂ in the gas phase above the solution and also to the concentration of malonic acid in the solution. Waves in solutions under N₂ or solutions covered with a perspex lid show effectively no depth effects. Dispersion relationships, the dependence of the wave speed on wavelength, are determined and tested against a recently proposed ‘universal form’. Direct imaging of the waves shows that in the presence of O₂, there is no wave propagation in the top 0.4 mm of solution, independent of the solution depth.