QUENCHING ANALYSIS OF THE BRIGGS-RAUSCHER REACTION

The Briggs-Rauscher oscillating reaction has been investigated at a su percritical Hopf bifurcation by an extensive series of quenching exper iments. Successful quenchings of the oscillations have been made by ad dition of IX-, I2, Mn2+, Mn3+, HOI, HIO2, H+, and OH-. It is remarkabl e that addition of OH- does not correspond to removal of H+. This fact suggests that H+ and OH- must be treated as independent species and t hat both may be important for elucidating the full mechanism of the re action. It has proved impossible to stop the oscillations by addition of any of the species IO3-, H2O2, CH2(COOH)2, or O2. Addition of Ag+ c an stop the oscillations, but the response differs from genuine quench ing. Addition of Ag+ cannot be viewed simply as removal of IX-. Four d istinct dilution experiments have been successfully made. Dilutions wi th water and with solutions containing various combinations of feed su bstances show that quenching by water is primarily due to removal of H + and Mn2+. Linear relations between the average concentrations, obtai ned from these experiments, provide bounds on concentrations. In parti cular we bracket the sum of the concentration of IX- and I2. Other rel ations provide an indication of a curvature of the stable manifold.