Two-dimensional turing-like patterns in the PA-MBO-System and effects of an electric field

In this work we present studies of a chemical reaction-diffusion system containing methyleneblue, sulfide, sulfite and oxygen embedded in a polyacrylamide gel matrix (PA-MBO-System). We have found several different quasi-stationary structures such as hexagons, stripes and zig-zag patterns similar to those observed in the well known CIMA reaction. We further examined the effect of an externally applied electric field on the observed structures. The electric field leads to the formation of striped patterns under conditions which favour the formation of hexagons in the absence of the held. The orientation of the stripes relative to the electric field vector depends on the strength of the field: While a weak electric field leads to stripes parallel to the held vector, higher held intensities lead to an orientation of the stripes perpendicular to it. The experimental results agree with model calculations based on an ionic Brusselator model.