FROZEN CHEMICAL WAVES IN THE BELOUSOV-ZHABOTINSKY REACTION

Chemical waves of the Belousov-Zhabotinsky reaction are frozen in by p recipitation of intermediates in a layer of silica gel using silver ni trate for the precipitation reaction. The distribution of the precipit ate corresponds to the global topology of propagating chemical waves. Inside the wave front (width 180-200 mu m) an additional thin precipit ation band (width 10-40 mu m) of dense precipitate is formed. This sha rp band vanishes first in annihilating waves. It surrounds the tip of spiral waves and disappears at the back side of the tip nearly half a front width away at a point, which can be localized in the range of 30 mu m. Comparison with spectrophotometric images of rotating spirals i ndicates that this point is located close to the rotation center of th e spiral and may be associated with a chemical singularity in the core region of the spiral wave.