The comparison of two methods used to observe a nonlinear system: potentiometry and holography

Abstract

The transition from state I ( characterized by low iodide and iodine concentration) to state II (high iodide and iodine concentration) occurs in a nonlinear Briggs-Rauscher (BR) oscillatory reaction. This transition was studied by two methods: potentiometric and holographic. The first derivative technique was applied to the obtained electrochemical and holographic curves of the transition state I→state II to obtain the corresponding slopes. Based on these slopes, the results of the two methods are compared. The obtained holographic slope for the transition from state I to state II is higher than the potentiometric one in all selected reaction sections. In the initial phase of the transition from state I to state II, it is clear that the velocity of the holographic method is twice that of the potentiometric method. While this trend shows a twofold increase at the beginning of the phase transition, it deviates in the other phases, where the holographic measurements show a 1.5-fold higher rate in the middle. The obtained results could have a strong impact on the study of nonlinear systems in the future.