New indicators for visualizing pattern formation in uncatalyzed bromate oscillatory systems
                        Orban M, Kurin-Csorgei K, Zhabotinsky AM, Epstein IR
                      JOURNAL OF THE AMERICAN CHEMICAL SOCIETY
                                 120 (6): 1146-1150 FEB 18 1998
Abstract:
Many uncatalyzed bromate oscillators (UBO's) undergo oscillations in electrochemical potential without any observable
color change in a closed, stirred (batch) system. We have investigated the effects of adding a wide variety of redox
indicators, including diphenylamine derivatives, azo dyestuffs, triphenylmethane derivatives, diimine chelate complexes, and
methylene blue to UBO's. We find that in many cases the indicators make the batch oscillations strikingly visible and also
allow observation of spatial pattern formation (concentric rings and spirals) in a thin, unstirred layer of solution. In some
systems, the indicators act merely to make visible changes in redox potential, while in others they play an active role in the
chemistry, and added indicator can lengthen the duration of oscillations or regenerate oscillations or patterns once this
behavior has ceased.