Dynamic Instability of Rydberg Atomic Complexes

Abstract

Atoms and molecules in highly excited (Rydberg) states have a number of unique characteristics due to the strong dependence of their properties on the values of principal quantum numbers. The paper discusses the results of an investigation of collisional Rydberg complexes specific features, resulting in the development of dynamic chaos and the accompanying diffusion autoionization processes. It is shown (experiment and theory) that, in subthermal low energies, the global chaotic regime that evolved in quasimolecular systems leads to significant changes in the Rydberg gases radiation/ionization kinetics. The effect of Förster resonance on the width of the fluorescence spectra and stochastic ionization processes in Rydberg systems is also discussed.

Redistribution of the Rydberg State Population Induced by Continuous-Spectrum Radiation

“…Thus, if only the transitions satisfying the Bethe rule are considered, then the population does not redistribute throughout all states but only those within the boundaries defined by the inequality (3).…”

“…The frequency of the induced transition cannot be lower than the difference of energies between the adjacent levels ω n = E n+1 − E n . Accordingly, if ω n exceeds ω min , ω n replaces ω min in (3). As a result, the upper boundary in Figure 1b is composite.…”

“…Interest in the diffusion-like redistribution of the Rydberg state population induced by radiation has been aroused by experimental observation of microwave ionization of hydrogen Rydberg states [1][2][3]. This process has been described within the framework of classical chaotic motion theory [4][5][6][7][8] or, alternatively, in terms of quantum diffusion [9].…”

Diffusive-like Redistribution in State-changing Collisions between Rydberg Atoms and Ground State Atoms

“…Following Ref. [35], inelastic collisions between Rydberg atoms and ground state atoms can often be subdivided into three phases: 1. the approach of the particles until they strongly couple to each other, 2. the formation of a Rydberg quasi-molecular complex at short internuclear distances and 3. the outcome of the collision, a state-change followed by dissociation or associative ionization. Applying this principle to the present case, the ionic core of the Rydberg atom and the neutral atom first approach each other, following the long-range PECs.…”

“…One might wonder, why the diffusive model describes the experimental observation so well, given its extreme simplicity and approximations. In fact, the exact microscopic ingredients are much more complex since the diffusion coefficient D in equation ( 7) is not necessarily a constant [35] and the oscillating electric dipole radiation field is far from being homogeneous. Moreover, we have completely ignored the n−1 angular momentum states of each manifold, which all have different matrix elements, and that the initial butterfly state is made up by a large number of angular momentum states.…”