Oscillations of EPR Signals Accompanying Belousov–Zhabotinsky Reaction

Р Б Моргунов ,Yoshifumi Tanimoto

doi:10.3390/magnetochemistry7010002

Abstract

Periodical transformation of ferroin to ferriin is accompanied by changes in magnetic properties of liquids during Belousov–Zhabotinsky (BZ) reaction malonic acid, sodium bromide, sodium bromate, ferroin, and sulfuric acid. Instead of the earlier studied oscillation of microwave conductivity accompanying an oscillating reaction, we propose a flash technique to interrupt the BZ reaction by rapid freezing. Rapid cooling of a solution during chemical oscillations results in a frozen system with a fixed concentration of paramagnetic centers Fe3+. EPR spectrum recorded at different stages of the interrupted reaction corresponds to the exact concentration of the ferroin and ferriin components. Following unfreezing unblocks the BZ reaction, and oscillations are still observed. A simulated spectrum allows one to distinguish two groups of Fe3+ ions of different symmetries. The obtained results are important to explain the earlier observed effect of inhomogeneous magnetic field on BZ reaction front velocity.

Highlights

Oscillation of color and physical properties of the solution accompanying the Belousov–Zhabotinsky (BZ) reaction is a classic demonstration of nonlinear dynamics of chemical reaction in open dynamical systems [1,2]
Since the electron paramagnetic resonance (EPR) spectrum of Fe2+ ions can be recorded below 20 K with a high-frehigh-frequency EPR spectrometer, we can exclude the contribution of these ions to the quency EPR spectrometer, we can exclude the contribution of these ions to the experiexperimental spectrum
The EPR spectra of the ferriin complexes were recorded in the frozen solution at subsequent oscillating stages of the BZ reaction

Summary

Introduction

Oscillation of color and physical properties of the solution accompanying the Belousov–Zhabotinsky (BZ) reaction is a classic demonstration of nonlinear dynamics of chemical reaction in open dynamical systems [1,2]. To temperature, humidity and concentration of impurities, BZ oscillations are sensitive to a magnetic field, which affects the propagation of the BZ reaction front [4,5]. The effect of the external magnetic field on BZ reaction is a result of magnetic force proportional to the gradient of the magnetic field. This force affects the paramagnetic ingredients of the reaction [4,5]. Our paper is motivated by the necessity to understand what paramagnetic particles involved in oscillating stages of BZ chemical reaction are subjected to magnetic force

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Discussion

Conclusion