Abstract
Chemical reactions involving free radicals can yield molecules with inverted populations of the nuclear Zeeman levels and able to store energy in the nuclear Zeeman reservoir. These molecules produce a radio-frequency electromagnetic field which induces radiative transitions between the Zeeman levels resulting in the conversion of the stored energy into radio-frequency emission from the molecules. The dependence of the recombination probability of the radicals on their spin state allows the elementary acts of radical reactions to be controlled by the application of radio-frequency electromagnetic fields ("chemical" radio receiver). The generation and reception of r.f. radiation in chemical reactions are the object of a new field of science: chemical radiophysics. 29 references.