Atomic parameters for carbon-like S XI

Radiative rates and collision strengths of S XI are presented for 46 levels of configurations 2s²2p², 2s2p³, 2p⁴, 2s²2p3s, 2s²2p3p, and 2s²2p3d.     

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Energies of the transitions 1s²2s²2p⁴?1s²2s2p⁵?1s²2p⁶ belonging to the isoelectronic sequence of oxygen have been calculated. The Hartre-Fock energy and the correlation energy, as well as relativistic corrections, were taken into account. The results have been compared with experimental data. Agreement was found to be good, thus suggesting that the $\text{(}\text{1}\text{Z}\text{)-}\text{expansion}$ converges rapidly. Perturbation theory was used for calculations of transition probabilities for the transitions 1s²2s²2p⁴?1s²2s2p⁵?1s²2p⁶ of the isoelectronic sequence of oxygen. The results may be useful in interpreting soft X-ray line radiation from these transitions, as observed in the solar corona and in high-temperature laboratory-generated plasmas.     

Tentatively identified and predicted H- Fano resonances

Positions are calculated for the Fano resonances that are due to interactions of the discrete autoionized 1s3s, 1s3p, and 1s4p states of H^- with overlapping split-configuration continua. The two first-mentioned resonances are tentatively identified with the diffuse interstellar doublets at λλ6376,6379 and λλ5780, 5797 on the basis of the relative positions of the autoionized states and the relative intensities of the doublet components.The observed wave-numbers of the 1s2s, 1s3s, 1s2p, and 1s3p resonances seem to belong to two series that converge towards a common limit in a kind of reverse Rydberg-series fashion. The position of the limit is close to 9000 Å, in accordance with theory. An extrapolation leads to the identification of the 1s4p resonance with the diffuse λ 6614 line. A further extrapolation leads to the prediction of positions at about 7183 and 7583 Å for the 1s5p and 1s6p resonances.The half-widths calculated for the singlet components of the 1s3p and 1s4p resonances are of the order of magnetude of those observed for the diffuse lines, and of the observed distance between the probably partly mixed singlet and triplet 1s3p components. The profile of the λ 5780 resonance is calculated on the basis of an assumed helium-line value for the oscillator strength. Its shape indicates that the “λ 5778 band” may be just a misinterpretation of the asymmetric wings.Tables of Hartree functions for the 3s², 3p² and 4p² configurations of H^- are given in an appendix.     

Energy Levels, Transition Probabilities, Collision Strength, and Reduced Population Calculations for High Gain Predictions in Neon-Like Krypton

We calculate the atomic structure, energy levels, oscillator strengths, transition probabilities, and collision strengths for Kr XXVII. The data refer to the 157 fine-structure levels belonging to the configurations (1s²) 2s² 2p⁶, 2s²2p⁵3l, 2s¹2p⁶3l, 2s²2p⁵4l, 2s¹2p⁶4l, 2s²2p⁵5l, and 2s¹2p⁶5l, where l?=?s, p, d, f, and the calculations are performed using the fully relativistic atomic structure program FAC. We use the obtained data to calculate the level populations and gain coefficients employing the MATLAB R2012a computer program for solving simultaneously the coupled rate equations. Finally, we determine the 157 fine-structure population levels and gain coefficients for those transitions with a positive inversion factor and plot the electron density in wide range from 10¹⁹ to 10²³.     

X-ray emission from multi-inner-shell excited states produced by high-intensity short-pulse X-rays

We study the double inner-shell ionization produced by high-intensity short-pulse X-rays and the X-ray emission from doubly inner-shell excited states of Mg (1s ²2s ²2p ⁴3s ²) and Xe (1s ²2s ²2p ⁶3s ²3p ⁶4s ²4p ⁶4d ⁸5s ²5p ⁶). The intensity and pulse width dependence on the X-ray emission is studied.     

Fine- and hyperfine structure analysis of the odd configurations in the lead atom

The fine- and hyperfine structure (hfs) analysis, on the basis of available experimental data for the configuration 6s ²6p6d+6s ²6p7s+6s ²6p8s in PbI has been performed. The Slater integrals, spin-orbit parameters and the effective hfs one-electron parameters have been determined. We find an off-diagonal core-polarization effect in the 6p6d+6p7s-space. Using the calculated radial parameters, the values of the quadrupole moment for stable and radioactive Pb-nuclei have been determined from measuredB-factors of the 6p7s ³P₁ state. In addition, a repulsion effect on the hfs sublevels with the same quantum numberF has been investigated.     

Oscillator strengths and transition probabilities of the Be(I) isoelectronic sequence for 2p2-2s2p and 2s2p-2s2 transitions

Oscillator strengths and transition probabilities are obtained from an intermediate coupling scheme. The initial basis of the eigenstates is formed inLS-coupling. To obtain the resulting energy matrix,Z^-1 perturbation theory is applied. The values of oscillator strengths and transition probabilities for 1s²2p²?1s²2s2p and 1s²2s2p?1s²2s² transitions are calculated and the comparison is made with some recent results. The nuclear charges (Z) involved varied fromZ=4(Be(I)) toZ=35(Br(XXXII)).     

Expected resonance line intensities in aluminum-like ions

Intensities of the 3s²3p?3s3p² and 3s²3p?3s²3d resonance lines in aluminum-like ions from Ar⁺⁵ to Sn⁺³⁷ are calculated for coronal plasma conditions, making use of oscillator strengths tabulated by Farrag, Luc-Koenig and Sinzelle.     

Calculation of Xe II line strengths and radiative lifetimes in intermediate coupling

Line strengths for 5s ² 5p ⁴ 6s?5s ² 5p ⁴ 6p transition in xenon are calculated in intermediate coupling scheme. The parametric potential method is used in calculating the radial part of the wave functions while the method of least squares fit of energy levels is applied in obtaining the angular part of the wave functions. Lifetimes of the 6p states obtained using these methods show a good agreement with data from electron-impact experiments.     

High gain predictions for Ni-like Gd ion

Atomic structure data and effective collision strengths for 1s² 2s² 2p⁶ 3s² 3p⁶3d¹⁰ and 54 fine-structure levels contained in the configurations 1s² 2s² 2p⁶ 3s² 3p⁶3d⁹4l (l = s, p, d, f) for the nickel-like Gd ion. These data are used in the determination of the reduced population for the 55 fine structure levels over a wide range of electron densities (from 10²¹ to 10²³) and at various electron plasma temperatures. The gain coefficient for those transitions with positive population inversion factor are determined and plotted against the electron density.     

Multiple ionization of neon 2s- and 2p-electrons induced by ion atom collisions

Absolute cross sections for production of the 1s ²2s2p ⁵ and 1s ²2s ⁰2p ⁶ configurations of neon in collisions of H⁺, He⁺, and Ne⁺ with Ne and He have been measured by observation of radiative transitions in the spectral range of the vacuum ultraviolet for energies between 50 keV and 1 MeV. Projectile and target emission have been separated. The dependence of the cross sections upon impact velocity is discussed and compared with theoretical calculations. The relative population of the¹ P ₁ and³ P _{2, 1, 0} and the³ P _{2, 1, 0} fine structure levels of the 1s ²2s2p ⁵ configuration is measured as function of impact velocity for the different projectile target combinations.     

Z-dependences of atomic characteristics of ions in Be- and O-isoelectronic sequences (2s−2p transition)

Transition energies and probabilities are presented for ions of the Be(Z = 4?100) and O(Z = 8?100) isoelectronic sequences. Dipole transitions are considered between all low-lying states constructed from 2s², 2s2p, and 2p² configuration in the case of Be-like ions, and between all low lying states from 2s²2p⁴, 2s2p⁵, and 2p⁶ configurations in the case of O-like ions. The calculations are based on the $\text{1}\text{Z}$ expansion technique and are carried out in the intermediate coupling scheme. Relativistic effects are incorporated using the Breit operator. For Z > 40, it is shown that jj-coupling is applicable. Results of the present calculations are compared with those of other authors over a broad range of nuclear charges.     

The probabilities of radiative transitions and lifetimes of levels in the spectra of Cu XX,La IV

The probabilities of radiative electric dipole transitions 2p ⁵3p, 2p ⁶–2p ⁵3s, and 2p ⁵3d in the spectrum of neon-like copper Cu XX and 5p ⁵6p, 5p ⁶–5p ⁵6s, 5p ⁵7s, and 5p ⁵5d in the spectrum of xenon-like lanthanum La IV are calculated. The wave functions of the intermediate coupling were found from the wellknown experimental energy levels by the least-squares method (LSM). To transfer to an absolute scale the radial integrals for the transitions calculated in the form of a length on the Hartree–Fock functions have been used. By summing the calculated probabilities of the transitions, the lifetimes of the levels of configurations 2p ⁵3s, 2p ⁵3p, and 2p ⁵3d in the spectrum of Cu XX and levels of configurations 5p ⁵6s, 5p ⁵6p, and 5p ⁵7s in the spectrum of La IV have been obtained.     

Study of the energy level structure for ions of the thallium isoelectronic sequence

The structure of the energy level diagram for 30 ions of the thallium isoelectronic sequence is studied on the basis of the relativistic Dirac-Fock self-consistent field method with the configuration interaction taken into account. It is discovered that the ground-state configuration and the lowest term change along the thallium isoelectronic sequence: At the beginning of the sequence, the ground-state configuration is 6s ²6p, and it becomes 6s ²6f beginning from the Cf¹⁷⁺ ion. On the basis of theoretical calculations, the ground-state ionization potentials are determined for each ion. The influence of interaction of the 6s6p ² configuration with the 6s ²6d configuration on the ² D _{3/2, 5/2} levels of the latter was also studied, and values of the fine-structure splitting of the 6s ²6p ² P ⁰ and 6s ²6d ² D levels were determined for the Tl-like ions considered.     

Population inversions in recombining hydrogen,nitrogen, and oxygen atomic plasmas

The possibility of population inversions in atomic hydrogen, oxygen and nitrogen plasmas has been investigated by solving a system of master equations describing the temporal evolution of the electronic levels exposed to the action of collisional and radiative processes. The results show that population inversions can be obtained for both quasistationary and fast, transient, recombining plasmas. In this case, the lasing durations of the transitions O(I) 3p³P-3s³S, 3p⁵P-3s⁵S and N(I) 3s²P-2p²D, 3s²P-2p²P⁰ are of the same order of magnitude as the collisional relaxation times of the original states.     

Tensor polarizabilities of levels of the configurations 4f 13 6s6p and 4f 12 5d6s 2 in thulium I

The level-crossing technique with parallel electric and magnetic fields was used to measure the tensor polarizabilities of six levels of the configuration 4f ¹³ 6s6p + 4f ¹² 5d6s ² in the Tm I-spectrum. Using intermediate coupling wave functions given by Camus and the experimental values of the tensor polarizabilities, the radial integrals for electric dipole transitions from levels of the configuration 4f ¹³6s6p + 4f ¹²5d6s ² to levels of the configuration 4f ¹³ 5d6s + 4f ¹² 6s ²6p have been determined. The results areI(4f ¹³6s6p,4f ¹³5d6s)=1.98(45)ea ₀ andI(4f ¹²5d6s ²,4f ¹²6s ²6p) = 0.88(25)ea ₀. A comparison between the experimental and the calculated values of the tensor polarizabilities shows an excellent agreement, provided that these radial integrals and the radial integrals for the electric dipole transitions to the ground state configuration 4f ¹³6s ² as determined by Wallenstein from lifetime measurements are used in the calculation, instead of radial integrals computed by Camus with Hartree-Fock wave functions.     

Study of the centrally produced ωρ0 and ωω systems inpp interactions at 300 GeV/c

We have performed a search for vector-vector final states centrally produced in proton proton interactions at 300 GeV/c using the CERN Ω spectrometer. Evidence is found for ωρ⁰ production in the reactionpp→p _f (2π⁺2π^?2π⁰)p _s and for ωω production in the reactionpp→p _f (2π⁺2π^?2π⁰)p _s . However no evidence is found for ωø production in the reactionpp→p _f (K ⁺ K ^?π⁺π^?π⁰)p _s .     

The shape of the 11S0 − 21P1 Fano resonance in the H- photo-ionization continuum

The interaction between the discrete autoionized state 1s2p of negative hydrogen and the overlapping split-configuration continuum is described in terms of stationary perturbations of nonorthogonal states that are eigenstates of two different first-order approximations to the Hamilton operator for the system.The eigenfunctions for the split-configuration states are taken to be those of a free p electron outside a neutral hydrogen atom in the ground state. The eigenfunction adopted for the short-lived, closed 1s2p configuration is the product of two functions that belong to symmetric Hartree-Fock eigenfunctions for the 1s²¹S and 2p²¹D states, respectively. This eigenfunction defines that Hamilton-operator approximation, of which the 1s2p state is an eigenstate.An improved Hamilton operator defines two different, but not independent, perturbation functions, one of which is a measure of the instability of the 1s2p configuration. The width of the resonance is found, correspondingly, to be determined by the product of two different perturbation terms. They are calculated in a Hartree-type approximation and found to be small, in part due to an effect of the nonorthogonality of the unperturbed states.The mean position of the singlet and triplet P Fano resonances in the ground state absorption continuum of H^- is found to be close to that of the diffuse interstellar bands at λ4430 and λ4760, but the calculated distance is about four times that of the bands. With exchange neglected and the position of maximum absorption fixed at λ4430 the singlet P resonance is found to have a width of 43 Å at half maximum, a minimum on the short-wave-length side, and a top absorption coefficient of 7 × 10^-16 cm²/ion, corresponding to an f value equal to 0.27.Tables of Hartree-Fock functions for the 2s²¹S, and the 2p²¹S, ¹D and ³P states of H^-, calculated by Claus Ingemann-Hilberg, are given in an appendix.     

Partial cross sections for Rb− photodetachment in the region of the Rb(5p 2 P 1/2 3/2) thresholds and their analysis by multichannel quantum defect theory

A crossed ion-laser beam apparatus has been used to measure accurate relative total and partial cross sections for photodetachment from Rb^? ions with high photon energy resolution (0.1–0.6 cm^?1) in the region of the Rb(5p ² P _1/2,3/2) thresholds (photon energy range 16,350–16,820 cm^?1). Satisfactory fits to these data by multichannel quantum defect theory (MQDT) have been obtained, resulting in a reliable set of seven MQDT parameters. The electron angular distribution parameter for the Rb(5_s) channel was found to beβ(5s)=2, independent of photon energy. MQDT predicts a sharp, window-type variation of?(5s) around the minimum of the 5s-cross section below the Rb(5p ² P _1/2) threshold (where an accurate experimental measurement ofβ(5s) was not possible) and a similar behaviour ofβ(6s) in the case of Cs^?photodetachment below the Cs(6p ² P _1/2) threshold.     

Structures and decay of deep-hole states in light nuclei populated by the (p, 2p 2p) reactions

Decay particles from the s-hole states in ¹¹B and ¹⁵N have been measured in coincidence with the quasifree ¹²C(p, 2p) and ¹⁶O(p, 2p) reactions at E _p =392 MeV. Triton decay is found to be dominant for the ¹¹B(s-hole) state and also found to be larger than α decay for the ¹⁵N(s-hole) state despite its smaller Q value compared to α decay. Measured decay branching ratios are discussed in comparison with the results of statistical-model, SU(3)-model, and shell-model calculations. The energy spectra around the s-hole states in both ¹¹B and ¹⁵N exhibit some bumplike structures, which can be qualitatively explained by recent shell-model calculations for both nuclei.