Energy levels and classifications of doubly-excited states in two-electron systems with nuclear charge, Z = 1, 2, 3, 4, 5, below the N = 2 and N = 3 thresholds

Below the thresholds for production of He⁺ in the N = 2 and N = 3 states the doubly-excited states in isoelectronic helium (Z = 1, 2, 3, 4, 5) have been completely classified as to series and outer quantum number by means of calculations using the truncated diagonalization method with hydrogenic basis functions. The classifications, energy levels, and effective quantum numbers are tabulated here for all systems with total orbital angular momentum L = 0, 1, 2, 3.     

Relativistic Dirac-Fock expectation values for atoms with Z = 1 to Z = 120

Numerical relativistic Dirac-Fock calculations for the average energy of the LS ground-state configuration of neutral atoms with Z = 1 to Z = 120 are presented. For open-shell systems a simple method is used to average over all the jj subconfigurations arising from the single LS configuration. The procedure of minimizing the average energy of the LS configuration allows a detailed comparison with nonrelativistic results and gives values slightly different from most of those previously published and obtained by considering only the lowest energy subconfiguration in jj coupling. Tabulations of total atom energies, orbital binding energies, one-electron integrals, expectation values of rⁿ for n = 6, 4, 2, 1, ?1, ?2, ?3, and the radius at which the orbital density has its maximum value are presented. A comparison with nonrelativistic Hartree-Fock results is given for elements with Z = 1 to Z = 100.     

Relativistic MR-MP calculations of the energy levels and transition probabilities in Ni- to Kr-like Pt ions

Ni- to Kr-like Pt ions have been studied by relativistic multi-reference Møller–Plesset many-body perturbation theory calculations. Energy levels and lifetimes of low-lying excited states within the n=4$n=4$ complex are reported for each ion. Wavelengths and transition probabilities for the strongest electric-dipole transitions are compared with available experimental data. Synthetic radiative spectra are shown for various wavelength regions.     

Experimental Coulomb displacement energies between analog energy levels of isobaric nuclei with A = 3 to A = 238

Presented here is a summary of the literature, up to January 31, 1974, on the excitation energies of analog energy levels in isobaric nuclei with A = 3 to A = 238. The summary was prepared to provide up-to-date values of the Coulomb displacement energies between accessible members of isospin multiplets. The results are presented in tabular form.     

Relativistic many-body Møller-Plesset perturbation theory calculations of the energy levels and transition rates in Na-like to P-like Xe ions

Relativistic multireference many-body perturbation theory calculations have been performed for Xe⁴³⁺ to Xe³⁹⁺ ions, resulting in energy levels, electric dipole transition rates, and level lifetimes. The second-order many-body perturbation theory calculation of energy levels included mass shifts, the frequency-dependent Breit correction, and Lamb shifts. The calculated transition energies and E1 transition rates are used to present synthetic spectra in the extreme ultraviolet range for some of the Xe ions.     

Calculated wavelengths,oscillator strengths,and energy levels for allowed n = 2–3 transitions in Be-like ions O V to Ni XXV

Calculated weighted oscillator strengths (O V to Ni XXV), wavelengths (Mg IX to Ni XXV), and energy levels (S XIII to Ni XXV) are listed for n = 2–3 transitions in ions belonging to the Be-like isoelectronic sequence along with available measured wavelengths (Mg IX to Ni XXV). They were computed with the aid of a Hartree-Fock-Relativistic computer program package which employs the Blume-Watson method for spin-orbit integrals. Configuration interaction was taken into account between the 2s², 2p², 2s3s, 2s3d, and 2p3p even configurations and the 2s2p, 2s3p, 2p3s, and 2p3d odd configurations. Ab initio values of Slater radial energy integrals were adjusted on the basis ofempirical data.     

Statistical thermodynamic study of the ternary compounds ThXyHx (X = C,N;y < 1;x < 2)

The stability and the nature of bonding in hypostoichiometric ThH₂, hcp ThC_0.46H_x and fcc ThN_yH_x (y = 0.486 and 0.692) are studied on the basis of statistical thermodynamics. The discussions are made in terms of the atomic partition function of H in these condensed phases and of the interaction energy terms. It is concluded that the nature of bonding in ThN_yH_x is approximately the same as that in ThH₂. On the other hand, the nature of bonding in ThC_yH_x is found to be significantly different from that in ThH₂.     

The populations of excited levels of hydrogen-like and helium-like ions in plasmas traversed by neutral hydrogen beams

This paper examines the populations of excited levels of impurity ions in a spatially homogeneous plasma containing primarily thermal electrons and protons and monoenergetic neutral hydrogen atoms. Of special concern is the role of recombination which may include the radiative, three-body and dielectronic processes together with charge exchange capture from neutral hydrogen beams.The influence of these primary processes on the populations is modified by radiative transitions and redistributive transitions due to collisions with electrons and protons in the plasma. The behaviour of the populations of the ions C⁵⁺, C⁴⁺ and Ar¹⁶⁺ with variation of plasma parameters is explored in the present work. A bundled principal quantum level picture and a more elaborate LS resolved picture are used which allow investigation of the expected spectral emission and its sensitivity to uncertainty in the primary rates.The variation of the impurity ion spectrum in transiently recombining or ionising conditions is also considered.     

Transition probabilities for the D and B′ vibrational levels to the X vibrational levels and continuum of H2

The electronic dipole-moment functions are used in calculating the transition probabilities for the individual bands of the $\text{D 3pπ}{}^1\text{Π}{}_{\mathrm{<mtext>u</mtext>}}\text{?X}{}^1\text{Σ}{}_{\mathrm{<mtext>g</mtext>}}{}^{\mathrm{+}}$ and $\text{B′ 3pσ}{}^1\text{Σ}{}_{\mathrm{<mtext>u</mtext>}}{}^{\mathrm{+}}\text{?X}{}^1\text{Σ}{}_{\mathrm{<mtext>g</mtext>}}{}^{\mathrm{+}}$ systems of H₂, and for the D and B′ vibrational levels to the $\text{X}{}^1\text{Σ}{}_{\mathrm{<mtext>g</mtext>}}{}^{\mathrm{+}}$ continuum.     

Relativistic energy levels, lifetimes, and transition probabilities for the sodium-like to argon-like sequences

Energy levels, lifetimes, and transition probabilities for transitions between computed levels are reported for the Na-like (Z = 11, … , 26) to Ar-like (Z = 18, … , 30) sequences. Several methods have been used—non-orthogonal spline CI, multiconfiguration Hartree-Fock (MCHF), and also multiconfiguration Dirac-Hartree-Fock (MCDHF). The first two methods included relativistic effects through the Breit-Pauli Hamiltonian, omitting only the orbit-orbit interaction. Both allowed (E1) and some forbidden (M1, E2, M2, E3) transitions are reported.     

Single electron capture by state-selected multiply charged Arq+ ions (q = 3,4)

State-selective single electron capture by multiply charged Ar^q+ ions (q = 3, 4) has been studied in rare gas targets with the aid of double translational spectroscopy. The energy gain spectra have been measured using different projectile beams, either extracted from an electron beam ion source or produced by electron capture reactions in an additional preparation cell. The influence of metastable projectile states as well as the reaction channel identification in complex systems are discussed.     

Relativistic multireference Møller-Plesset perturbation theory calculations of the energy levels and transition probabilities in Ne-like xenon, tungsten, and uranium ions

Relativistic multireference many-body Møller-Plesset perturbation theory (MR-MP) calculations have been performed on neonlike xenon, tungsten, and uranium ions. The 2s⁻¹n? and 2p⁻¹n? (n ? 5, ? ? 4) energy levels, lifetimes and transition probabilities are reported. The second-order MR-MP calculation of energy levels included mass shifts, frequency-dependent first-order Breit correction and Lamb shifts. The calculated transition energies are compared with other theoretical and experimental data. The synthetic radiative spectra is presented for different wavelength regions.     

Rydberg and autoionizing triplet states in Helium up to the N = 5 threshold

Energy levels of highly excited bound Rydberg states, the position and widths of autoionizing states, and oscillator strengths are calculated for He ³S, ³P^e, ³P^o, ³D^e and ³D^o symmetries up to the N = 5 He⁺ excitation threshold. The calculations are performed with the K-matrix B-spline method with maximum orbital angular momentum ?_max = 8. Reliable doubly excited-state parameters up to the n = 20 multiplet below each ionization threshold are presented. One thousand and six hundred newly identified bound and metastable states, seven times those available in literature, fill many gaps, reveal a dozen intruder states, and allow new speculations on propensity rules and radiative decays of triplet Rydberg states.     

Calculated wavelengths,oscillator strengths,and energy levels for n = 2−2 and 2–3 transitions in F-like ions Mg IV to Ni XX and for 3−3 and other transitions in Mg IV,Al V,and Si VI

Weighted oscillator strengths, energy levels, and wavelengths are calculated for the 2s²2p⁵-2s2p⁶, 2s²2p⁵-2²2p⁴3s, and 2s²2p⁵-2s²2p⁴3d transition arrays for F-like ions in the isoelectronic sequence from Mg IV to Ni XX and in addition for n = 3?3 and other transitions in Mg IV, Al V, and Si VI. The calculation involves the computation of ab initio values of Slater radial energy integrals using a Hartree-Fock-Relativistic computer program package, which includes configuration-interaction and applies the Blume-Watson method for spin-orbit integrals. Some of the parameters are subsequently optimized on the basis of empirical data. Adopted values are tabulated along with atomic energy level compositions.     

Extraction mechanisms of uranyl ions by 1-butyl-3-methylimidazolium nonafluorobutanesulfonate containing N-dodecyl-2-pyrrolidone

Extraction of U(VI) in HNO₃ to 1-butyl-3-methylimidazolium nonafluorobutanesulfonate (BMINfO) by using N-dodecyl-2-pyrrolidone as an extractant has been investigated. With increasing the concentration of HNO₃ from 0.01 to 3.0 mol/dm³ (M), distribution ratio decreased. This suggests that uranyl ions are extracted by ion exchange with a cation component of BMINfO, i.e. BMI⁺. The amount of BMI⁺ transferred to aqueous phase accompanied by extraction of U(VI) was evaluated with ¹H NMR measurement. Plots of the amount of U(VI) extracted versus the amount of BMI⁺ transferred from BMINfO phase to the aqueous phase indicated linear relationship. The slope of the line was about 1.0 and 0.63 in the extraction system of U(VI) performed in 0.1 and 1.0 M HNO₃, respectively. This result means that two types of extraction mechanisms exist depending on the concentration of HNO₃. One is the ion exchange mechanism. Another is the ion-pair extraction mechanism.     

Resonant coherent excitation of 2s electron of Li-like Fe ions to the n = 3 states

We observed resonant coherent excitation of the 2s electron to the n = 3 states of 83.5 MeV/u Li-like Fe²³⁺ ions planar-channeling in the plane of a Si crystal. A survival fraction of the Li-like ions was measured as a function of the angle between the incident beam and the [0 0 1] axis. Clear resonance dips corresponding to the transitions of a 2s electron to all the n = 3 states were observed. The transition of each resonance dip was identified by comparing with spectroscopic data. The resonance dips at the transition energies corresponding to the optically forbidden 2s_1/2–3s_1/2, 2s_1/2–3d_3/2 and 2s_1/2–3d_5/2 transitions were observed as well as the resonance dips at transition energies corresponding to the optically allowed 2s_1/2–3p_1/2 and 2s_1/2–3p_3/2 transitions.     

Atomic ion energies for Na-like ions by a model potential method Z = 25–80

The energies of the states 3s, 4s, 5s, 3p, 4p, 5p, 3d, 4d, 5d, 4f, 5f, and 6f of ions of the Na-like series with nuclear charge Z = 25–80 are presented. The energies have been calculated by a model potential method, the model potential for arbitrary nuclear charge Z being constructed from available experimental data for the first members of the series.     

Pair production and bremsstrahlung contributions to the stopping of relativistic heavy ions

We examine the energy loss to electron–positron pairs and bremsstrahlung for relativistic heavy ions penetrating matter. Pair production is the dominant source of loss at extreme projectile energies, and already at energies of a few hundred GeV/u it may add several per cent to the stopping power. An analytical formula for the pair-production contribution to the average energy loss is produced. In bremsstrahlung coherent action of the constituents of each collision partner is required in order to keep the nuclei from breaking up. This limits the emission substantially at high energies compared to the emission in collisions between pointlike non-composite but otherwise similar objects. A simple formula for the bremsstrahlung loss is presented. We conclude with remarks on the statistics of the energy-loss processes.     

Reaction list for charged-particle-induced nuclear reactions Z = 1 to Z = 98 (H to Cf), July 1972–June 1973

This Reaction List for charged-particle-induced nuclear reactions has been prepared from the journal literature for the period July 1972 through June 1973. Each published experimental paper is listed under the target nucleus in the nuclear reaction with a brief statement of the type of data in the paper. The nuclear reaction is denoted by A(a,b)B, where M_a≥ (one nucleon mass). There is no restriction on energy. Nuclear reactions involving mesons in the outgoing channel are not included. Theoretical papers which treat directly with the analysis of nuclear reaction data and results are included in the Reaction List.     

Lamb shift measurements in high Z hydrogenic ions

This paper presents a possible technique for the measurement of the ground state Lamb shift in hydrogenic krypton, Kr³⁵⁺, via a comparison of the Lyman α and Balmer β wavelengths. Measurements of the yields of the Lyman α transitions in Kr³⁵⁺ using krypton beams at 18.6, and $\text{34 MeV}\text{A}$ are described.