Double-diffusive cellular fingering in the horizontally propagating fronts of the chlorite–tetrathionate reaction

Horizontally propagating chemical fronts have been studied in the acid-catalyzed chlorite–tetrathionate reaction. Unusual cellular fingers develop in a relatively thin solution layer. Double-diffusive convection is among the driving forces in the pattern formation arising from the addition of a polyelectrolyte which immobilizes and reversibly removes the autocatalyst hydrogen ion in a controlled manner and drastically slows down the front. Convection therefore becomes significant in the thin horizontal solution layer. To corroborate our results we have measured the solution densities and viscosities, and determined the diffusion coefficients by PFGSE 1H-NMR.