Resonant-excitation-double-autoionization process in the electron-impact ionization of Li-like ions

We have calculated the contributions of excitation-autoionization and resonant-excitation-double-autoionization indirect-ionization mechanisms to electron-impact ionization of Li-like ${\mathrm{B}}^{2+}$, ${\mathrm{C}}^{3+}$, ${\mathrm{N}}^{4+}$, ${\mathrm{O}}^{5+}$, and ${\mathrm{F}}^{6+}$ ions. We considered twelve autoionizing states arising from the 1s2${\mathit{s}}^2$, 1s2s2p, 1s2${\mathit{p}}^2$, 1s2s3s, and 1s2s3p configurations. Rydberg series 1s2s2ln’l’ and 1s2s3ln’l’ of resonances, which arise due to the resonant-excitation-double-autoionization process, are included in our calculation. The calculated resonance structures in the cross sections agree very well with recent crossed-beam measurements.