Dielectric recombination from Ni-like Mo in singly-excited levels through the doubly-excited Cu-like 3d⁹4ln′l′(n′ ≤ 9) complexes in dense plasmas

Dielectronic recombination (DR) rate coefficients are usually calculated employing a low-density coronal model, in which it is assumed that the free electron is captured by an ion in its ground state and that no additional collisional processes occur thereafter. In the present work, we address the issue of DR processes of ions in singly-excited levels through the example of a Ni-like Mo ion. DR rate coefficients of Ni-like Mo in the 3d⁹4l excited levels are calculated with a level-by-level computation using the Hebrew University Lawrence Livermore Atomic Code (HULLAC). The calculations are performed for DR through the doubly excited Cu-like complexes 3d⁹4ln′ l′ (n′ ≤ 9) that were found to be the main DR channels for Ni-like ions in the ground state, and assuming that no collisional processes occur after the dielectronic capture. The results show that for an electron density of 10²¹ cm^-3 the mean rate coefficients for DR via 3d⁹4ln′ l^′ (n′ ≤ 9) are drastically reduced due to the population of the excited levels of the recombining ion.