Effects of Ion Core in Rydberg Atom-Neutral Collisions

Abstract

In this chapter we shall continue to study the excitation (de-excitation), quenching, and ionization of highly excited atoms induced by collisions with neutral particles. However, our attention will be focused here on the analysis of the alternative physical mechanisms of these processes accounted for by the scattering of the perturbing neutral particle B on the parent core A⁺ of the Rydberg atom A*. This is, first of all, the most efficient mechanism of resonant energy exchange between the highly excited electron and inner electrons of the quasi-molecule B A⁺ +- e temporally formed during the scattering of atom B on the ion core A⁺. The identified mechanism plays usually the major role in the processes of associative and direct ionization, as well as, in the inelastic excitation (de-excitation) of the Rydberg atom in thermal collisions with the ground-state atoms. We shall also consider the dipole-induced n-changing transitions and ionization processes due to the mechanism of energy exchange between the Rydberg electron and translational motion of the colliding atoms. A theoretical description of the identified processes will be given within the framework of the quasi-molecular approach. Another separated atom-approach combined with the sudden perturbation theory will allow us to analyze transitions between highly excited states induced by the “shake up” of the Rydberg electron in the perturber-core scattering (the so-called noninertial mechanism).