Inward propagating chemical waves in a single-phase reaction-diffusion system

We report our experimental and theoretical studies of inwardly propagating chemical waves (antiwaves) in a single-phase reaction-diffusion (RD) system. The experiment was conducted in an open spatial reactor using chlorite-iodide-malonic acid reaction. When the system was set to near Hopf bifurcation point, antiwaves appeared spontaneously, as predicted using both the reaction-diffusion (RD) equation and the complex Ginzburg-Landau equation (CGLE). Antiwaves change to ordinary waves when the system was moved away from the Hopf onset, which still agreed with RD simulations but could not be predicted by CGLE. We thus witnessed a new type of antiwave-wave exchange. Our analysis showed that this exchange occurred when the CGLE broke down as the system was far from the Hopf onset.