Signature of Quantum Interference in Photorecombination of Ar-Like Ions

We analyze both experimental (Schippers {\it et al.}, J.~Phys.~B {\bf 31}, 4873 (1998); Phys.~Rev.~A {\bf 65}, 042723 (2002)) and calculated total cross sections for dielectronic recombination (DR) of Ar-like Sc$^{3+}$ and Ti$^{4+}$ ions in the vicinity of the $3p^{5}3d^{2}$ and $3p^{5}3d4s$ doubly-excited, highly-correlated resonances. Our R-matrix approach provides a unified quantum-mechanical description of the electron-ion photorecombination (PR) process, treating radiative recombination and DR as coherently interfering pathways for the rare asymmetric profiles of the strong $3p^{5}3d^{2}$ $^{2}F_{7/2,5/2}$ near-threshold resonances. In order to treat the PR completely and more practically, all additional (Lorentzian) resonance contributions for the rest of the Rydberg series are calculated within an independent-processes, isolated-resonance, distorted-wave approximation using the atomic structure and collision code AUTOSTRUCTURE.