Complex dynamical behavior in the highly photosensitive cerium-bromate-1,4-benzoquinone reaction

Experimental and numerical investigations are carried out on the nonlinear dynamics of the cerium-bromate-1,4-benzoquinone reaction in which a unique kinetic feature is that the reduction of Ce(IV) is through bromide ions rather than by organic substrates. Nonlinear phenomena including both simple and sequential oscillations have been observed, and the system could oscillate for longer than a week. Significantly, fluorescent ceiling light with an intensity of less than 20 μW/cm(2) exhibited strong influence on the frequency, lifetime, and complexity of the spontaneous oscillations. The transient oscillations lasted for a longer period of time at a low light intensity, were quenched by a moderate illumination, and then became long-lived again at a higher light intensity. Characterizations with (1)H NMR and GC/MS spectroscopy and ion selective electrode suggest that 2-bromo-1,4-benzoquinone is an important unstable intermediate product that undergoes photoaccelerated decomposition to produce hydroxy-1,4-benzoquinone and bromide ions. Simulations successfully reproduced the occurrence of oscillatory behavior in the studied system.