Excitation of ions of the lithium isoelectronic sequence in the relativistic Coulomb-Born approximation

Abstract

Cross sections for the electron-impact excitation of the $2p_{\frac{1}{2}}$ and $2p_{\frac{3}{2}}$ states of the lithiumlike ions ${\mathrm{C}}^{3+}$, ${\mathrm{Fe}}^{23+}$, ${\mathrm{Mo}}^{39+}$, and ${\mathrm{W}}^{71+}$ are calculated in the relativistic Coulomb-Born approximation. A range of incident electron energies from the $2p_{\frac{1}{2}}$ threshold to (approximately) ten times the $2p_{\frac{3}{2}}$ threshold is considered. The most significant relativistic effects result from the spin-orbit splitting of the $2p$ states. An interpolation formula is presented which permits the estimation of these cross sections for similar ions of intermediate charges.