Measure for the effect of quantum interference between radiative and dielectronic recombination

The electron-ion photorecombination (PR) cross section is known to have an asymmetric energy profile, as a result of quantum interference between direct radiative and dielectronic recombination. We introduce a parameter that reflects the degree of this asymmetry and use it to identify PR transitions for which the effects of interference may be observable. Significantly asymmetric PR cross-section profiles are found for a few PR transitions from He-like Ar and Fe via ${1s2l2l}^{\ensuremath{'}}$ autoionizing levels. The profile asymmetry parameter provides a physical measure for the scaling of the interference effect with the ion charge.