Photoionization of ground and excited states of Ca$^{+}$ and comparison along the isoelectronic sequence

Photoionization cross section calculations are performed on the ground ([Ne]3$s^{2}$3$p^{6}$4$s \quad ^{2}$S$_{1/2}^e )$ and the first two excited ([Ne]3$s^{2}$3$p^{6}$3$d \quad ^{2}$D$_{3/2}^e $ and [Ne]3$s^{2}$3$p^{6}$3$d$ $^{2}$D$_{5/2}^e )$ states of Ca$^{+}$ ions for photon energies from threshold to 45.0 eV using the relativistic (Breit-Pauli) R-matrix method. The discrete Ca$^{2+}_{ }$orbitals are generated using the computer program AUTOSTRUCTURE; 30 configurations are included in the configuration-interaction (CI) calculation for Ca$^{2+}$. The most prominent 3\textit{p $\to $ 3d }giant resonances are analyzed and identified, and our results are compared with experimental results, and rather good agreement is found. Using results of our previous photoionization calculations on Sc$^{2+}$ and Ti$^{3+}$ ions, the strongest and broadest resonances in the photoionization cross section of those three ions (Ca$^{+}$, Sc$^{2+}$ and Ti$^{3+})$, are compared in terms of width and oscillator strengths to show the evolution as a function of nuclear charge. This work is supported by DOE and NSF.