Within the semiclassical approximation chemi-ionization processes during symmetrical-atom-Rydberg-atom collisions were considered, as well as the inverse chemi-recombination processes during the scattering of free electrons by corresponding collisional ion–atom complexes and molecular ions. It was shown that these processes must be taken into account when modelling the low-temperature layers of the solar atmosphere and the atmospheres of some helium-rich stars.

The influence of the H - H+ - e and H-2(+) - e chemi-recombination processes on the highly excited hydrogen atom population in the photosphere and lower part of the chromosphere has been considered. It has been shown that these chemi-recombination processes have an important role in the large region around the temperature minimum in the Solar atmosphere, where they are comparable to the other relevant recombination processes, or even dominant and that they should be taken into account for the modelling of the weakly ionized layers in the Solar atmosphere.

Within the semi-classical approximation, chemi-ionization processes during symmetrical atom-Rydberg atom collisions were considered, as well as the inverse chemi-recombination processes during the scattering of free electrons by corresponding collisional ion-atom complexes and molecular ions. It was shown that these processes must be taken into account when modelling the low-temperature layers of solar atmosphere and atmospheres of some helium- rich stars.