Relativistic many-body calculations of electric-dipole lifetimes, transition rates and oscillator strengths for 2l⁻¹3l′ states in Ne-like ions

Abstract

Transition rates, oscillator strengths and line strengths are calculated for electric-dipole (E1) transitions between odd-parity 2s22p53s, 2s22p53d and 2s2p63p states and even-parity 2s22p53p, 2s2p63s and 2s2p63d states in Ne-like ions with the nuclear charges ranging from Z = 14 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate retarded E1 matrix elements in length and velocity forms. The calculations start from a 1s22s22p6 Dirac–Fock potential. First-order RMBPT is used to obtain intermediate coupling coefficients and second-order RMBPT is used to calculate transition matrix elements. Contributions from negative-energy states are included in the second-order E1 matrix elements to ensure the gauge independence of transition amplitudes. Transition energies used in the calculation of oscillator strengths and transition rates are from second-order RMBPT. Lifetimes of the 16 even-parity and 18 odd-parity levels are given for Z = 14–100. Transition rates, line strengths and oscillator strengths are compared with critically evaluated experimental values and with results from other recent calculations. These atomic data are important in the modelling of L-shell radiation spectra of heavy ions generated in electron beam ion trap experiments and in L-shell diagnostics of plasmas.

Producing ultrashort, ultraintense plasma-based soft-x-ray laser pulses by high-harmonic seeding

“…Furthermore, as Loudon states [31], the effective equivalence between the rate and density matrix equations is "most easily studied" in the limit of low intensity when Ω 2 ∝ I γ γ sp , where γ is the total line broadening and γ sp is the natural component due to spontaneous emission. For the example we give of seeding at 0.01I s under the revised conditions, because of the extent of collisional broadening, this condition is also satisfied using the results of Safronova et al [32]. The ultrahigh intensities result from focusing down to close to the diffraction limit after the seeded pulse has exited the plasma amplifier.…”

Correlation and relativistic effects in actinide ions

“…[6,[13][14][15][16][17][18][19] for calculation of multipole matrix elements for transitions from excited states to the ground state, and in Refs. [6,[20][21][22] for calculation of multipole matrix elements for transitions between excited states. The calculations are carried out using a basis set of Dirac-Fock (DF) orbitals.…”

Identification and Plasma Diagnostics Study of Extreme Ultraviolet Transitions in Highly Charged Yttrium

“…Line identifications were inferred from comparisons with spectra simulated from the collisional-radiative model NOMAD based on a non-Maxwellian distribution designed for EBIT-like environments. For Ne-like Y ions, a better agreement between theory and experiment was found using relativistic many-body perturbation theory (RMBPT) [68]. Several of the identified forbidden M1 transitions were found to be potentially useful for density diagnostics of laboratory, fusion and astrophysical plasmas.…”

“…We report fourteen E1 and one M1 transitions in Ne-like Y. The Ne-like yttrium lines were identified using the theoretical values from highly accurate RMBPT calculations [68].…”

“…We note that for electron beam energies below 3.75 keV, where M-shell yttrium ion charge states become prominent, a more accurate relativistic many-body perturbation theory (RMBPT) calculation had to be invoked to match theoretical and experimental data. These calculations were performed by Safronova et al [68] for the lines of the Ne-like, Na-like, Mg-like and Al-like charge states of yttrium lines.…”