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

Modem collision theory of Rydberg atoms with neutral and charged parti cles is;presented. Recent results on the excitation, ionization, quenc hing and broadening of highly excited atomic states are reported. We c onsider in detail a number of approaches: various versions of perturba tion theory, classical and semiclassical methods, Fermi pseudopotentia l model, impulse approximation and quasimolecular approach. Analytical and numerical methods developed within the framework of these differe nt approaches presented in this review give both the simple qualitativ e description of elementary processes with Rydberg atoms and also reli able quantitative results. Both quasielastic transitions with small en ergy defect (l- and J-mixing processes) and the inelastic bound-bound and bound-free transitions with large energy transfer (n-changing proc esses, direct and associative ionization) are considered. In addition to the traditional mechanism of the perturber-quasifree electron scatt ering we analyze some efficient physical mechanisms due to the scatter ing of the perturbing atom or molecule on the atomic care of Rydberg a tom. Considerable attention is paid to the comparison of theoretical r esults with available experimental data.