Energy levels,wavelengths, and transition rates of multipole transitions (E1, E2, M1, M2) in Au and Au ions

The fully relativistic configuration interaction method of the FAC code is used to calculate atomic data for multipole transitions in Mg-like Au (Au⁶⁷⁺) and Al-like Au (Au⁶⁶⁺) ions. Generated atomic data are important in the modeling of M-shell spectra for heavy Au ions and Au plasma diagnostics. Energy levels, oscillator strengths and transition rates are calculated for electric-dipole (E1), electric quadrupole (E2), magnetic dipole (M1), and magnetic quadrupole (M2) for transitions between excited and ground states 3l−nl^′$3l-n{l}^{\prime }$, such that n=4,5,6,7$n=4,5,6,7$. The local central potential is derived using the Dirac–Fock–Slater method. Correlation effects to all orders are considered by the configuration interaction expansion. All relativistic effects are included in the calculations. Calculated energy levels are compared against published values that were calculated using the multi-reference many body perturbation theory, which includes higher order QED effects. Favorable agreement was observed, with less than 0.15% difference.     

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.     

Energies and E1, M1, E2, M2 transition rates for states of the 2s22p, 2s2p2, and 2p3 configurations in boron-like ions between N III and Zn XXVI

Energies, E1, M1, E2, M2 transition rates, line strengths, oscillator strengths, and lifetimes from relativistic configuration interaction calculations are reported for the states of the (1s²)2s²2p, 2s2p², and 2p³ configurations in all boron-like ions between N III and Zn XXVI. Valence, core–valence, and core–core correlation effects were accounted for through single–double multireference (SD-MR) expansions to increasing sets of active orbitals.     

Energies and E1, M1, E2, and M2 transition rates for states of the 2s2p, 2s2p,and 2p configurations in nitrogen-like ions between F III and Kr XXX

Based on relativistic wavefunctions from multiconfiguration Dirac–Hartree–Fock and configuration interaction calculations, E1, M1, E2, and M2 transition rates, weighted oscillator strengths, and lifetimes are evaluated for the states of the (1s²)2s²2p³,2s2p⁴, and 2p⁵ configurations in all nitrogen-like ions between F  III and Kr  XXX. The wavefunction expansions include valence, core–valence, and core–core correlation effects through single–double multireference expansions to increasing sets of active orbitals. The computed energies agree very well with experimental values, with differences of only 300–600 cm⁻¹ for the majority of the levels and ions in the sequence. Computed transitions rates are in close agreement with available data from MCHF-BP calculations by Tachiev and Froese Fischer [G.I. Tachiev, C. Froese Fischer, A&A 385 (2002) 716].     

E2,M1 multipole mixing ratios in odd-mass nuclei,A > 150

A survey is presented of the E2,M1 multipole mixing ratios of gamma-ray transitions in odd-mass nuclei with A > 150. Angular distribution and correlation measurements reported in the literature have been analyzed in terms of a consistent choice of the phase relationship between the E2 and M1 matrix elements. Presented is a set of recommended values which is based whenever possible on an average of results from various studies. For the strongly deformed nuclei, these values are grouped and analyzed according to the Nilsson configurations assigned to the levels. In order to facilitate the analysis in terms of Nilsson states, the angular distribution and correlation data are complemented by the inclusion of some selected determinations of the multipole mixing ratios from internal-conversion-coefficient measurements. The survey includes data available in the literature up to December 1975.     

Energy level calculations and E1M1 two photon transition rates in two electron U90+

The recent development of heavy ion sources capable of producing two-electron ions all the way up to U⁹⁰⁺ makes possible many new experiments to measure relativistic and QED effects in the high Z regime. The calculation of energy levels for these ions is discussed, along with the exotic E1M1 two photon transition rate from the 1s2p ³P₀ state. The E1M1 rate of 5.64 × 10⁹ s^?1 is about 46% of the allowed E1 decay rate.     

E2, M1 multipole mixing ratios: Supplement and corrections through December 1979

Presented here is an updated compilation of E2, M1 multipole mixing ratios based on analysis of angular distribution and correlation data from the literature. The present compilation includes data which have appeared in the literature subsequent to the publication of previous compilations of this series, and also includes data for odd-Z, odd-N nuclei which have not been previously surveyed. Several cases are noted in which previously accepted spin assignments or multipole mixing ratios have been shown by more recent data to be incorrect. The present compilation includes data from the literature up to December 1979.     

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.     

Band transition moments between excited singlet states of the H2 molecule,nonadiabatic eigenvectors,and probabilities for spontaneous emission

The electronic dipole transition moments of Wolniewicz are used to calculate the vibrational-electronic band transition moments and probabilities for spontaneous emission in the adiabatic and nonadiabatic approximations for the H₂ molecule in the ($\text{EF, GK, H}\text{H}$) ¹Σ_g⁺-(B, B′)¹Σ_u⁺, C¹Π_u systems. The electronic integrals over the nuclear-momentum operators which describe the nonadiabatic coupling within the J = 0 states of EF, GK, and $\text{H}\text{H}{}^1\text{Σ}{}_{\mathrm{<mtext>g</mtext>}}{}^{\mathrm{+}}$, computed by Wolniewicz, are used to obtain nonadiabatic vibrational-electronic ¹Σ_g⁺ eigenfunctions.     

Relativistic energy, fine structure, and hyperfine-structure studies of the high-lying core-excited states P(n) (n = 1-3) and S(m) (m = 1-3) for the Be-like isoelectronic sequence

The variational method using a multiconfiguration interaction wavefunction is carried out on the high-lying core-excited states ⁵P(n) (n = 1-3) and ⁵S^o(m) (m = 1-3) for the Be-like isoelectronic sequence from Z = 7 to 10, including mass polarization and relativistic corrections. Relativistic energies, oscillator strengths, wavelengths, and lifetimes are reported. The results are compared with other theoretical and experimental data in the literature. The fine structure and hyperfine structure of core-excited states for this system are also investigated.     

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.     

He+ (np) cross sections for 2, 3, 4 and 5 MeV C4+ ions colliding with He atoms

The cross sections of ionization plus excitation of He are measured by the C⁴⁺ + He prototype reaction with energies ranging from 2 to 5 MeV. Theoretically the independent electron approximation is used to calculate the HeII (np) ionization plus excitation cross sections. The results of the calculations are compared with our experimental data.     

Measurements and model calculations of activation cross sections for 232Th(n,2n)231Th reaction between 13.57 and 14.83 MeV neutrons

In this study, activation cross sections were measured for the reaction of ²³²Th(n,2n)²³¹Th (T_1/2 = 25.5 h) by using neutron activation technique at six different neutron energies from 13.57 and 14.83 MeV. Neutrons were produced via the ³H(²H,n)⁴He reaction using SAMES T-400 neutron generator. Irradiated and activated high purity Thorium foils were measured by a high-resolution γ-ray spectrometer with a high-purity Germanium (HpGe) detector. In cross section measurements, the corrections were made for the effects of γ-ray self-absorption in the foils, dead-time, coincidence summing, fluctuation of neutron flux, low energy neutrons. For this reaction, statistical model calculation, which the pre-equilibrium emission effects were taken into consideration, were also performed between 13.57 and 14.83 MeV energy range. The cross sections were compared with previous works in literature, with model calculation results, and with evaluation data bases (ENDF/B-VII, ENDF/B-VI, JEFF-3.1, JENDL-4.0, JENDL-3.3, and ROSFOND-2010).     

Negative ions, energy loss, and electron emission during grazing scattering of fast H and He atoms from a clean and oxidized NiAl(1 1 0) surface

Negative ion fractions, projectile energy loss, and the emission of electrons is studied for grazing scattering of hydrogen and helium atoms/ions from a clean and oxidized NiAl(1 1 0) surface. Making use of translation energy spectroscopy and the coincident detection of the number of emitted electrons we have studied the electronic interaction mechanisms for the change from a clean metal target to an insulator surface via the preparation of a well defined ultrathin alumina film on top of the metal substrate. We find that already for a monolayer thick oxide film the characteristic different features of electronic processes for the surface of an insulator crystal are present.     

Systematics for (n, 2n) excitation functions in the neutron energy between 13.4 and 14.9 MeV

A systematics of (n, 2n) partial excitation functions was studied on the basis of our 58 sets of experimental data measured using intense neutron source facilities of FNS at the Japan Atomic Energy Agency and of OKTAVIAN at Osaka University. The empirically predictive formulas based on the evaporation theory are applicable for the neutron energy between 13.4 and 14.9 MeV, and in the mass range between 14 and 238. About 83% of the cross sections and the slopes of excitation functions can be reproduced within an uncertainty of 15%. The formulas were expressed in terms of a mass number A, an asymmetry parameter S = (N ? Z)/A, and threshold energies of the (n, 2n) and (n, 3n) reactions, where N and Z are the neutron and proton numbers for the target nuclei, respectively. The excitation functions were well reproduced for the nuclei in the region with S < 0.05 and 14 ? A ? 58 for the first time. The general characteristics of the excitation functions, consisting of steep rising in the light mass nuclei, gently-sloping or nearly flat in the middle and heavy mass nuclei, and slow falling in the heavy mass regions with possible (n, 3n) reactions, are well expressed.     

Molecular dynamics simulations of C2, C2H, C2H2, C2H3, C2H4, C2H5, and C2H6 bombardment of diamond (1 1 1) surfaces

The sticking and erosion of C₂H_x molecules (where x=0-6), at 300 and 2100 K onto hydrogenated diamond (1 1 1) surfaces was investigated by means of molecular dynamics simulations. We employed both quantum-mechanical and empirical force models. Generally, the sticking probability is observed to somewhat increase when the radical temperature increases and strongly decrease with increasing number of H atoms in the molecule.     

空气条件下合成的CaBPO5:Eu、SrB4O7:Eu和Ba3(PO4)2:Eu的XANES和发光性质

测定了采用高温固相反应在空气条件下合成的发光体CaBPO5：Eu、SrB4O7：Eu和Ba3(PO4）2：Eu的Eu-L3边的X射线吸收近边结构(XANES)谱和发光光谱。从发光体的Eu—L3边XANES可见，Eu^3 -L3边能量比Eu^2 -L3边能量高7—8eV；3个发光体的激发光谱和发射光谱均可看到Eu^2 的4f-5d跃迁和Eu^3 的4f-4f跃迁。发光体的Eu—L3边的XANES和发光光谱说明空气条件下合成的发光体中Eu^3 可部分还原为Eu^2 。     

Thermodynamic properties of ThxU1−xO2 (0 < x < 1) based on quantum-mechanical calculations and Monte-Carlo simulations

Th_xU_1−xO_2+y binary compositions occur in nature, uranothorianite, and as a mixed oxide nuclear fuel. As a nuclear fuel, important properties, such as the melting point, thermal conductivity, and the thermal expansion coefficient change as a function of composition. Additionally, for direct disposal of Th_xU_1−xO₂, the chemical durability changes as a function of composition, with the dissolution rate decreasing with increasing thoria content. UO₂ and ThO₂ have the same isometric structure, and the ionic radii of 8-fold coordinated U⁴⁺ and Th⁴⁺ are similar (1.14 nm and 1.19 nm, respectively). Thus, this binary is expected to form a complete solid solution. However, atomic-scale measurements or simulations of cation ordering and the associated thermodynamic properties of the Th_xU_1−xO₂ system have yet to be determined. A combination of density-functional theory, Monte-Carlo methods, and thermodynamic integration are used to calculate thermodynamic properties of the Th_xU_1−xO₂ binary (ΔH_mix, ΔG_mix, ΔS_mix, phase diagram). The Gibbs free energy of mixing (ΔG_mix) shows a miscibility gap at equilibration temperatures below 1000 K (e.g., E_exsoln = 0.13 kJ/(mol cations) at 750 K). Such a miscibility gap may indicate possible exsolution (i.e., phase separation upon cooling). A unique approach to evaluate the likelihood and kinetics of forming interfaces between U-rich and Th-rich has been chosen that compares the energy gain of forming separate phases with estimated energy losses of forming necessary interfaces. The result of such an approach is that the thermodynamic gain of phase separation does not overcome the increase in interface energy between exsolution lamellae for thin exsolution lamellae (10 Å). Lamella formation becomes energetically favorable with a reduction of the interface area and, thus, an increase in lamella thickness to >45 Å. However, this increase in lamellae thickness may be diffusion limited. Monte-Carlo simulations converge to an exsolved structure [lamellae || ] only for very low equilibration temperatures (below room temperature). In addition to the weak tendency to exsolve, there is an ordered arrangement of Th and U in the solid solution [alternating U and Th layers || {1 0 0}] that is energetically favored for the homogeneously mixed 50% Th configurations. Still, this tendency to order is so weak that ordering is seldom reached due to kinetic hindrances. The configurational entropy of mixing (ΔS_mix) is approximately equal to the point entropy at all temperatures, indicating that the system is not ordered.