Relativistic multiconfiguration Dirac-Fock calculations of photoionization, electron-impact ionization, Auger decay, and relaxed-orbital oscillations of Cu ions

Core-hole creation and decay are of tremendous importance in both theory and applications. However, different ionization approaches and decay channels, especially at L-shell, bring many challenges to accurate simulation. In order to understand the ionization state effects on the creation and decay at L-shell hole, we performed a theoretical study of photon/electron-impact L-shell ionization of differently charged copper ions and the subsequent Auger electron and fluorescence emission by using the relativistic multiconfiguration Dirac-Fock approach. It was found that photoionization has much larger cross sections than electron-impact ionization near the ionization threshold, but smaller ones at higher impact energies. The ionization cross sections for 2s-sublevels are negligibly small compared with those for 2p-sublevels for both photon and electron impact ionizations. Additionally, the ionization cross sections decrease with the ionization state for both electron- and photonimpact L-shell ionizations. Similar to radiative (fluorescence) decay, Auger kinetic energy and yield decrease with ionization state, and the energy gaps and rate ratios between major Auger transitions change with ionization state. Furthermore, Auger rates from the L-shell decay are much larger than fluorescence rates, and the Auger-to-fluoresce decay ratio slightly decreases with increase in the ionization state of Cu ion.