Inhibitory effect of oxygen on excitation waves in the Belousov–Zhabotinsky reaction with different excitability

Oxygen diffuses into an open-air surface of a vertically oriented thin layer of the Belousov–Zhabotinsky reaction and creates a millimeter-order inhibited layer where excitation fronts cease. When the excitability of the reaction is weakened via a decrement of [H2SO4] or [NaBrO3], the velocity of spiral waves located far from the open-air surface decreases and the width of the inhibited layer increases. The experimental findings agree well with simulations using the Oregonator model where the excitability is adjusted via two parameters ɛ−1 and f which mimic the change in [H2SO4] or [NaBrO3] and the oxygen profile along the vertical direction, respectively.