Sprecher
Beschreibung
The energy-resolved merged beams recombination rate coefficient α(E) for dielectronic recombination (DR) of O2+ has been measured on an absolute scale in the energy range from 0 to 45 eV. The experimental data comprises all ∆N=0 DR series associated with 2s → 2p core excitations and the lowest ∆N=1 DR series limits associated with 2p → 3s and 2p → 3d core excitations. In addition, we have performed corresponding quantum theoretical calculations using a freely available atomic code. From the combined experimental and theoretical data, we have derived a temperature-dependent plasma recombination rate coefficient α(T) for dielectronic recombination. In comparison to previously published theoretical data, we find excellent agreement for the temperature range, where O2+ is abundant in high-temperature plasmas dominated by collisional ionization. However, in the temperature range where O2+ exits in photoionized plasmas, our DR rate coefficient is a factor of two larger than the previously published ones. This should be relevant, e.g., for an accurate determination of the recently discovered surprisingly large oxygen abundances in early galaxies.
