Do periodic chemical reactions reveal Fürth's quantum diffusion limit?

The present paper deals with an interesting problem, unresolved for more than 70 years, concerning class of diffusion-controlled periodic chemical reactions, where macroscopically observed diffusion action attains, with appreciable accuracy, the value of Planck's quantum ℏ. Starting from the classical Einstein-von Smoluchowski theory of Brownian movement and making use of a significant fact that classical and quantum Brownian processes are essentially indistinguishable in configuration space, a simple criterion for the accessibility of Fürth's quantum diffusion limit has been formulated. The application of this criterion to experimental data has proved that the quantum nature of a stochastic process controlling these periodic reactions is very likely.