Do periodic chemical reactions reveal Fürthʹs 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 Planckʹs 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 Fürthʹs 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.