Scroll waves in the Belousov–Zhabotinsky reaction: exploitation of O2-effect on the ferroin-catalysed system

The inhibiting effect of dissolved oxygen on wave propagation in the ferroin-catalysed Belousov–Zhabotinsky (BZ) reaction is exploited to obtain three-dimensional scroll waves experimentally in this system. The development of the scrolls is monitored by imaging the wave evolution via a video camera and image acquisition software. Solutions for which the initial waves are initiated under an atmosphere of pure oxygen have a subexcitable or inhibited layer of typically 1 mm depth. Once the O2 is replaced by N2, this layer regains excitability and a scroll wave structure can develop. For waves initiated under air, the depth of the inhibited layer is less and scroll waves do not develop. A simple extension of the ZBKE model for the ferroin system is proposed and shown to predict the oxygen inhibition in reasonable agreement with experiment.