Critical size and curvature of wave formation in an excitable chemical medium.

The critical radius for the outward propagation of waves in an excitable solution of the Belousov-Zhabotinskii reaction was experimentally analyzed and found to be approximately 20 mum, being in a range predicted by theory. Thus, the wave initiation depends on the critical radius in an all-or-none fashion. For waves having high positive curvature of wave fronts, a linear relationship between the curvature and their normal velocity was established, allowing computation of a diffusion coefficient of 1.9 x 10(-5) cm(2)/s for the autocatalytic species, which agrees well with results previously obtained for negatively curved wave fronts. The analysis of the dispersion of wave velocity yielded the decrease of wave velocity for small initiation periods as predicted theoretically.