Electron-Ion Recombination Rate Coefficients and Photoionization Cross Sections for Astrophysically Abundant Elements. IX. Ni XXVI and Ni XXVII for Ultraviolet and X-Ray Modeling

Relevant data is available at: http://www.astronomy.ohio-state.edu/~nahar/nahar_radiativeatomicdata/index.htmlThe inverse processes of photoionization and electron-ion recombination of (hv + Ni XXVI ↔ Ni XXVII + e) and (hv + Ni XXVII ↔ Ni XXVIII + e) are studied using the unified method for the total recombination. The method subsumes both the radiative and dielectronic recombination processes and enables self-consistent sets of results for photoionization and electron-ion recombination by using the same wavefunction for these inverse processes. Photoionization cross sections (σ_PI), recombination cross sections (σ_RC), recombination collision strengths (Ω_RC), and recombination rate coefficients (α_RC) are obtained for ionization balance and spectral analysis of UV and X-ray lines. Level-specific photoionization cross sections and recombination rates are presented to enable accurate computation of recombination-cascade matrices for all fine-structure levels n (l SLJ) up to n ≤ 10 : 98 bound fine-structure levels of Ni XXVI with 0 ≤ l ≤ 9, 0 ≤ L ≤ 11, and 1/2 ≤ J ≤ 17/2, and 198 levels of Ni XXVII with 0 ≤ l ≤ 9, 0 ≤ L ≤ 14, and 0 ≤ J ≤ 10. Total α_RC-values for Ni XXVI and Ni XXVII are compared with the existing values and are found to be in very good agreement. Total recombination rate coefficients for the hydrogen-like recombined ion, Ni XXVIII, are also presented. The calculations are carried out in the relativistic Breit-Pauli R-matrix (BPRM) approximation with inclusion of radiation damping of resonances. With consideration of all details of the processes, the results, which include the level-specific σ_PI and α_RC calculated for the first time, should be the most accurate for these ions.This work was supported partially by NSF and NASA