Relativistic configuration-interaction calculations of the energy levels of the 1s22l and 1s2l2l′

Abstract

We present systematic calculations of energy levels of the 1s 2 2l and 1s2l2l ′ states of ions along the lithium isoelectronic sequence from carbon till chlorine. The calculations are performed by using the relativisticconfiguration-interaction method adapted to the treatment of autoionizing core-excited states. The relativistic energies are supplemented with the QED energy shifts calculated within the model QED operator approach. A systematic estimation of the theoretical uncertainties is performed for every electronic state and every nuclear charge. The results are in agreement with existing high-precision theoretical and experimental data for the ground and first excited states. For the core-excited states, our theory is much more accurate than the presently available measurements.

Reference-free measurements of the1s2s2p2P1/2,3/2o→Machado1, Bian2, Paul3 et al. 2020Phys. Rev. A131130View full textAdd to dashboardCite

“…For three-electron ions there are very accurate measurements and calculations for the 1s 2 2p 2 P J → 1s 2 2s 2 S 1/2 transitions, for elements up to very heavy ones like lead, bismuth, thorium, and uranium [21][22][23][24][25][26][27][28] using both EBITs and accelerators. For these systems, overall good agreement is found between all the available experiments and the most advanced calculations [1,[29][30][31][32].…”

“…We find that only one transition has a significant fluorescence yield (0.97) and an energy very close to our value. It is the 1s2p 2 [32] and 2417.132 eV in our FAC calculation, but its fluorescence yield is only 0.17. The same study in Ar did not provide evidence for this line, as the statistics of the spectra are lower.…”

“…There is generally good agreement between successive experiments and between experiment and the most advanced theoretical calculations from the present work and from Refs. [31,32,115]. However, some older publications, e.g., [112,114,116,117], provide values that differ by approximately 1 eV, because of the lack of proper QED corrections.…”

Photoionization of metastable heliumlike C4+(1s2sS13Müller1, Lindroth2, Bari3 et al. 2018Phys. Rev. ASelf Cite390420View full textAdd to dashboardCite

“…The very high accuracy of resonance energies obtained by the present theoretical treatment may be exploited in an envisaged effort at the PIPE setup to generate new secondary reference standards for the calibration of soft-x-ray beamlines at synchrotron-radiation sources. A viable scenario would be the transfer of the calibration obtained from the very accurately calculated photoionization-resonance energies of selected heliumlike (and lithiumlike [59,60]) ions to the neutral-gases-based calibration standards that are presently used. Full advantage of the existing high-precision theoretical resonance energies can only be taken if an improved control of the photon-beam energy at beamline P04 can be realized which includes the stable positioning of the electrons circulating in the PETRA III storage ring.…”

“…In a recent publication, level energies for 1s 2 2 and 1s2 2 states in lithiumlike ions with atomic numbers Z between 6 and 17 have been presented [59,60] with uncertainties of a few meV, much smaller than the typical calibration uncertainties of common neutral-gas standards. Transitions in lithiumlike C 3+ through Ne 7+ would adequately cover the energy range of interest with resonances at about 300 eV to more than 900 eV.…”