Atom-Rydberg-atom chemi-ionization processes in solar and DB white-dwarf atmospheres in the presence of (n - n')-mixing channels

Abstract

In this paper, the rate coefficients of the chemi-ionization processes in H(1s) + H*(n, l) and He(1s2) + He*(n, l) collisions (where the principal quantum number n ≫ 1) are determined for the first time, taking into account the influence of the corresponding (n - n')-mixing processes. It is demonstrated that the inclusion of (n - n') mixing in the calculation influences the values of chemi-ionization rate coefficients significantly, particularly in the lower part of the block of Rydberg states. The interpretation of this influence is based on two existing methods of describing inelastic processes in symmetrical atom-Rydberg-atom collisions. The calculations of the chemi-ionization rate coefficients are performed for the temperature region that is characteristic of solar and DB white-dwarf atmospheres.