Gel-free experiments of reaction-diffusion front kinetics

We present a gel-free experimental system to study the kinetics of the reaction front in the A + B --> C reaction-diffusion system with initially-separated reactants. The experimental setup consists of a CCD camera monitoring the kinetics of the front formed in the reaction-diffusion process Cu2+ + tetra [disodium ethyl bis(5-tetrazolylo) acetate trihydrate] --> 1:1 complex, in aqueous, gel-free solution, taking place inside a 150 mum gap between two flat microscope slides. The experimental results agree with the theoretical predictions for the time dependence of the front's width, height, and location, as well as the global reaction rate.