ORIGIN OF SPONTANEOUS WAVE GENERATION IN EXCITABLE CHEMICAL-SYSTEMS

We investigate the origin of spontaneous chemical wave generation in an excitable Belousov-Zhabotinskii system. We solve one-dimensional reaction-diffusion equations of an Oregonator model with the initial profiles possessing an excitation of varying concentration of either HBrO2 or Br-, and the excitation occurs within a region of different length. The concentration of the threshold excitation necessary for a wave to propagate depends on the length within which the initial excitation is applied. We further perform an equilibrium stochastic calculation of the recurrence time for a thermal fluctuation to induce a change in concentration of a sufficient magnitude within a sufficient volume for a wave to propagate. The smallest recurrence time calculated is 10(17) s. We compare our results with previous experimcnts and calculations and conclude from all the evidence that an internal thermal fluctuation is highly unlikely to generate a chemical wave in an excitable chemical solution.