Transition rates for a Rydberg atom surrounded by a plasma

We derive a quantum master equation for an atom coupled to a heat bath represented by a charged particle many-body environment. In the Born-Markov approximation, the influence of the plasma environment on the reduced system is described by the dynamical structure factor. Expressions for the profiles of spectral lines are obtained. Wave packets are introduced as robust states allowing for a quasiclassical description of Rydberg electrons. Transition rates for highly excited Rydberg levels are investigated. A circular-orbit wave-packet approach has been applied in order to describe the localization of electrons within Rydberg states. The calculated transition rates are in a good agreement with experimental data.

Figure 1

Boundary between classical and quantum mechanical descriptions of the hydrogen electron at $T=300$ K for different densities.

Figure 2

Transition rates of $n_i=13$ to near $n_f$ states induced at a $T=300$ K electron plasma with density $n_{\mathrm{pl}}={10}^9{\mathrm{cm}}^{-3}$, calculated from the wave-packet description with the width ${\sigma }_{n_0}=0.55$ and ${\sigma }_{n_0}=0.75$ compared to the results from classical Monte Carlo simulation (MCS) [69], the calculation in the Born approximation with and without collision effects from Ref. [29], and experimental data [70].

Figure 3

Transition rates of $n_i=40$ to near $n_f$ states induced by a $T=20$ K electron plasma with density $n_{\mathrm{pl}}={10}^9{\mathrm{cm}}^{-3}$, calculated from the wave-packet description with the width ${\sigma }_{n_0}=0.5,2,3$ compared to the results from classical Monte Carlo simulation [69] (green line) and the results in the Born approximation with and without collision effects from Ref. [67].