Effects of quantum interference between radiative and dielectronic recombination on photorecombination cross-section profiles for the He-like ions Ar16+ and Fe24+

Total cross sections for electron-ion photorecombination (PR) processes are calculated using a projection-operator and resolvent-operator approach. This approach provides a unified quantum-mechanical description of the combined electron-ion PR process, including radiative and dielectronic recombination as coherent, interfering components. An especially adapted version of the Hebrew-University Lawrence-Livermore Atomic Code HULLAC is developed and employed for the calculations. In particular, PR cross sections for He-like argon and iron ions are calculated for incident-electron energies in the vicinity of the 1s2l2l' and 1s2l3l' doubly-excited, autoionizing levels of the Li-like ions. Significant effects of quantum interference between radiative and dielectronic recombination, in the form of asymmetric PR cross-section profiles, are predicted, especially for weak transitions. The general behavior of the interference effect, as a function of the ion charge q and as a function of the principal quantum number n' of the outer electron in the autoionizing state, is investigated using a hydrogenic-scaling analysis. It is found that the degree of asymmetry in the PR cross-section profile can be substantial for close-to-neutral ions and also for very highly-charged ions. In the intermediate-charge regime, on the other hand, the asymmetry is anticipated to be less prominent. The dependence of the quantum-interference effect on n' is predicted to be much weaker