COLLISION-THEORY OF RYDBERG ATOMS WITH NEUTRAL AND CHARGED-PARTICLES

Modem collision theory of Rydberg atoms with neutral and charged particles is;presented. Recent results on the excitation, ionization, quenching and broadening of highly excited atomic states are reported. We consider in detail a number of approaches: various versions of perturbation theory, classical and semiclassical methods, Fermi pseudopotential model, impulse approximation and quasimolecular approach. Analytical and numerical methods developed within the framework of these different approaches presented in this review give both the simple qualitative description of elementary processes with Rydberg atoms and also reliable quantitative results. Both quasielastic transitions with small energy defect (l- and J-mixing processes) and the inelastic bound-bound and bound-free transitions with large energy transfer (n-changing processes, direct and associative ionization) are considered. In addition to the traditional mechanism of the perturber-quasifree electron scattering we analyze some efficient physical mechanisms due to the scattering of the perturbing atom or molecule on the atomic care of Rydberg atom. Considerable attention is paid to the comparison of theoretical results with available experimental data.