Photoionization cross-section calculations are performed on potassiumlike transition metal ions (Ti${}^{3+}$, ${\mathrm{V}}^{4+}$, Cr${}^{5+}$, Mn${}^{6+}$, and Fe${}^{7+}$) using both nonrelativistic ($\mathit{LS}$-coupling) and relativistic (Breit-Pauli) $R$-matrix methods for the ground ([Ne]$3s$${}^{2}3$$p$${}^{6}3$$d$ ${}^2$$D$${}_{3/2}^e$) and the first excited ([Ne]$3s$${}^{2}3$$p$${}^{6}3$$d$ ${}^2$$D$${}_{5/2}^e$) states of each of the five ions, along with the excited $4s$ ${}^2$$S$ state of Ti${}^{3+}$. Photon energies up to the first $3p$ ionization threshold are considered. The results show that for Ti${}^{3+}$, the cross sections are dominated by the giant ($3p\to 3d$) resonances which are analyzed and identified, while for the four other ions (V${}^{4+}$, Cr${}^{5+}$, Mn${}^{6+}$, and Fe${}^{7+}$), the $3p\to 3d$ resonances lie below the ionization threshold, and the cross sections are dominated by $3p$${}^{5}3$$\mathit{dnd}$ and $3p$${}^{5}3$dn’s Rydberg series of resonances. Comparison of the Ti${}^{3+}$ results with available theoretical and experimental data shows good agreement.

• Received 28 June 2010

DOI:https://doi.org/10.1103/PhysRevA.82.043416