Ferroin-induced complex oscillations in the bromate-hydroquinone photochemical reaction

This study presents an experimental investigation on the dynamics of the ferroin-bromate-hydroquinone photoreaction, in which two isolated oscillatory regimes emerge due to the presence of ferroin. Oscillations within the two isolated regimes exhibit different dependence on light intensity and initial compositions of the reaction solution. A phase diagram outlining the occurrence of the new oscillatory regime has been established in the bromate-ferroin concentration plane. As opposed to the ferroin-free system, in which there is nearly no difference in the reaction behavior whether benzoquinone or hydroquinone is used as the starting reactant, here the two-staged oscillatory behavior can only be obtained with hydroquinone as the initial reagent. This observation suggests that the reduction of ferriin by hydroquinone and the autocatalytic oxidation of ferroin by acidic bromate may have played a major role in the new oscillation window.