Scroll waves in the Belousov-Zhabotinsky reaction: exploitation of O-2-effect on the ferroin-catalysed system

The inhibiting effect of dissolved oxygen on wave propagation in the ferroi n-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 cia a video camera and image acquisition software. Solutions for which the initial waves are i nitiated under an atmosphere of pure oxygen have a subexcitable or inhibite d layer of typically 1 mm depth. Once the O-2 is replaced by N-2, this laye r regains excitability and a scroll wave structure can develop. For waves i nitiated under air, the depth of the inhibited layer is less and scroll wav es do not develop. A simple extension of the ZBKE model for the ferroin sys tem is proposed and shown to predict the oxygen inhibition in reasonable ag reement with experiment.