Experimental cross sections for electron-impact ionization of iron ions: ${\mathrm{Fe}}^{5+}$, ${\mathrm{Fe}}^{6+}$, and ${\mathrm{Fe}}^{9+}$

Absolute cross sections have been measured for electron-impact ionization of Fe ions of initial charges 5+, 6+, and 9+ from below threshold to 1500-eV collision energies. Distorted-wave calculations including only direct ionization from ground-state ions underestimate the measured peak cross sections by 60–70?due to the effects of metastable states and contributions of excitation autoionization to the total cross sections. Ionization rate coefficients and fitting parameters are presented for this data and for ${\mathrm{Fe}}^{+}$ and ${\mathrm{Fe}}^{2+}$.