Atomic Spectra Database

Systematic variation of the electron-beam energy in an electron-beam ion trap has been employed to produce soft-X-ray spectra of Os, Bi, Th, and U with highest charge states ranging up to Ni-like ions. Guided by relativistic atomic structure calculations, the strongest lines have been identified with {Delta}n = 0 (n = 4 to n' = 4) transitions in Rb- to Cu-like ions. The rather weak 4p-4d transitions are much less affected by QED contributions than the dominant 4s-4p transitions. Our wavelength measurements consequently provide benchmarks with and (almost) without QED. Because the radiative corrections are not very sensitive to the number of electrons in the valence shell, our data, moreover, provide benchmarks for the evaluation of electron-electron interactions.

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Soft-X-ray spectra of highly charged Os, Bi, Th, and U ions in an electron beam ion trap

We study various properties of the $2p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2}\ensuremath{-}2p\phantom{\rule{0.16em}{0ex}}^{2}P_{3/2}$ fine-structure splittings in the boronlike ${\mathrm{S}}^{11+}, {\mathrm{Cl}}^{12+}, {\mathrm{Ar}}^{13+}$, and ${\mathrm{K}}^{14+}$ ions and the $4p\phantom{\rule{0.16em}{0ex}}^{2}P_{1/2}\ensuremath{-}4p\phantom{\rule{0.16em}{0ex}}^{2}P_{3/2}$ fine-structure splittings in the galliumlike ${\mathrm{Nb}}^{10+}, {\mathrm{Mo}}^{11+}, {\mathrm{Tc}}^{12+}$, and ${\mathrm{Ru}}^{13+}$ ions to find out the feasibility of using these highly charged ions as suitable optical atomic clocks. The roles of the electron correlations due to the Dirac-Coulomb-Breit Hamiltonian and accounting for lower-order quantum electrodynamics effects are shown explicitly in the calculations of electron affinities, excitation energies, transition-matrix elements, lifetimes, hyperfine-structure constants, and electric quadrupole moments of the states involved with clock transitions using a relativistic couple-cluster method. We also estimate the most commonly appearing systematic effects in the atomic clock experiments due to the electric quadrupole, the second-order Zeeman, both the dc and ac Stark, and the black-body radiation shifts in the aforementioned fine-structure splittings to demonstrate typical orders of magnitude of fractional frequency shifts.

Investigating ground-state fine-structure properties to explore suitability of boronlike S 11 + − K 14 + and galliumlike Nb 10 + − Ru 13 + ions as possible atomic clocks

We are measuring the cross sections for the 3d → 4f and 3d → 5f excitations in Ni- to Ga-like Au in beam plasmas created in the Livermore electron beam ion trap EBIT-I. The measurements are possible by using the high-resolution broadband coverage of the Goddard Space Flight Center micro-calorimeter. The cross sections are determined from the ratio of the intensity of the collisionally excited lines to the intensity of the radiative recombination lines. The value of the excitation cross section of the 3d 3/2  → 5f 5/2 transition in Au 50+ (Cu-like) is presented and compared to distorted wave calculations.

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Measurement of Electron Impact Collisional Excitation Cross Sections of Ni to Ga-Like Gold

The use of the magnetic-field-induced transition (MIT) in Fe X for the measurement of the magnetic field strength in the solar corona has been discussed and demonstrated in a number of recent studies. This diagnostic technique depends on, among other conditions, the accuracy of the atomic data for Fe X. In the present work, we carry out a large-scale calculation for the atomic properties needed for the determination of the MIT rate using the multiconfiguration Dirac-Hartree-Fock method. Four computational schemes are employed to study the convergence of the atomic properties of interest. Comparison with other experimental and theoretical sources are performed and recommended values are suggested for important properties, e.g., the magnetic induced transition probabilities as a function of magnetic field strengths. The present calculations affect magnetic field measurements by decreasing the magnetic field strengths by 10%-15%, leading to differences in magnetic energy up to 30%. We recommend that the current data should be employed in magnetic field measurements in the future. (Less)

A Theoretical Investigation of the Magnetic-field-induced Transition in Fe X, of Importance for Measuring Magnetic Field Strengths in the Solar Corona

Energies, wavelengths, transition probabilities, oscillator strengths, and line strengths have been calculated for 4s24p–4s4p2 and 4s24p–4s24d transitions in gallium-like ions from Z = 60 to 65, for Nd XXX, Pm XXXI, Sm XXXII, Eu XXXIII, Gd XXXIV, and Tb XXXV using the fully relativistic multiconfi guration Dirac–Fock method. The correlation with the n = 4 complex and the quantum electrodynamic effects have been considered in the calculations. The obtained results have been compared with the available experimental and other theoretical results.

Energies, Wavelengths, and Transition Rates for Ga-Like Ions (Nd XXX–Tb XXXV)

Excitation energies, LS-compositions, and lifetimes for the 184 fine-structure levels related to the 2s2, 2p2, 2snl (n = 3 − 6;  l = 0 − 4), and 2pnl (n = 3 − 5;  l = 0 − 4) configurations as well as transition data for the electric/magnetic-dipole (E1/M1) and electric/magnetic-quadrupole (E2/M2) transitions between these levels are calculated for Be-like Ag XLIV and Cd XLV. The GRASP2018 atomic structure computer package, which is based on the multiconfiguration Dirac-Hartree-Fock (MCDHF) method, is used to perform the present computations. The Breit interaction and quantum electrodynamics (QED) effects are included in the relativistic configuration interaction (RCI) computations. The convergence of excitation energies for various active sets is discussed and the discrepancy between the present energies and oscillator strengths with other theoretical results is graphically illustrated. The uncertainty estimation of the present results for lifetimes and line strengths is performed by comparing the two active sets of the present MCDHF calculations.

Relativistic excitation energies and transition data for Ag XLIV and Cd XLV

Energy levels, wavelengths, oscillator strengths, transition probabilities and lifetimes have been calculated for Be-like Xe, Cs, Ba, La, and Ce ions among the fine-structure levels of terms belonging to the 2s2, 2s2p, 2p2, 2s3s, 2s3p, 2s3d, and 2p3d configurations. The calculations have been performed using the fully relativistic multiconfiguration Dirac-Fock (MCDF) method, taking the quantum electrodynamic corrections (QED) into account. The results are compared with the available other theoretical results.

Energies and transition rates for Be-like ions (Xe LI - Ce LV)

Energy levels and lifetimes for the lowest 204 fine-structure levels belonging to the 2s22p, 2s2p2, 2p3, 2s23l, 2s2p3l, 2p23l, 2s24l, 2s2p4l, and 2p24l (l = s,  p,  d,  f) configurations of B-like Pd XLII are calculated using the multiconfiguration Dirac-Hartree-Fock (MCDHF) method, as well as wavelengths, transition probabilities, weighted oscillator strengths, and line strengths for electric dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) transitions among these levels. In the calculations, the contributions from Breit interaction and quantum electrodynamics (QED) corrections are taken into account. Comparisons are made with available theoretical energies and electric dipole oscillator strengths.

Energy levels, wavelengths, and transition probabilities for transitions in Pd XLII

Energy levels, wavelengths, transition probabilities, oscillator strengths, and line strengths have been calculated for allowed electric dipole 4s
 2
 4p–4s4p
 2
 and 4s
 2
 4p–4s
 2
 4d transitions of Gallium-like ions from Z = 54 to 59, Xe XXIV, Cs XXV, Ba XXVI, La XXVII, Ce XXVIII, and Pr XXIX. The fully relativistic multiconfiguration Dirac–Fock method, taking into account both correlations within the n = 4 complex and the quantum electrodynamic effects, has been used in the calculations. The results have been compared with the available experimental and other theoretical results.

Fatma El-Sayed

Papers

Energies, Wavelengths, and Transition Rates for Ga-Like Ions (Nd XXX–Tb XXXV)

Relativistic excitation energies and transition data for Ag XLIV and Cd XLV

Energies and transition rates for Be-like ions (Xe LI - Ce LV)

Energy levels, wavelengths, and transition probabilities for transitions in Pd XLII

Energy Levels and Transition Rates for GA-Like Ions (Xe XXIV–Pr XXIX)