Ulyana I. Safronova

Blackbody radiation shift, multipole polarizabilities, oscillator strengths, lifetimes, hyperfine constants, and excitation energies in Ca +

A systematic study of Ca + atomic properties is carried out using high-precision relativistic allorder method where all single, double, and partial triple excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the levels up to n = 7. Recommended values and estimates of their uncertainties are provided for a large number of electric-dipole transitions. Electric-dipole scalar polarizabilities for the 5s, 6s, 7s, 8s, 4pj, 5pj, 3dj, and 4dj states and tensor polarizabilities for the 4p3/2, 5p3/2, 3dj, and 4dj states in Ca + are calculated. Methods are developed to accurately treat the contributions from highly-excited states, resulting in significant (factor of 3) improvement in accuracy of the 3d5/2 static polarizability value, 31.8(3) a 3, in comparison with the previous calculation [Arora et al., Phys. Rev. A 76, 064501 (2007)]. The blackbody radiation (BBR) shift of the 4s 3d5/2 clock transition in Ca + is calculated to be 0.381(4) Hz at room temperature, T = 300 K. Electric-quadrupole 4s nd and electric-octupole 4s nf matrix elements are calculated to obtain the ground state multipole E2 and E3 static polarizabilities. Excitation energies of the ns, np, nd, nf, and ng states with n � 7 in are evaluated and compared with experiment. Recommended values are provided for the 7p1/2, 7p3/2, 8p1/2, and 8p3/2 removal energies for which experimental measurements are not available. The hyperfine constants A are determined for the low-lying levels up to n = 7. The quadratic Stark effect on hyperfine structure levels of 43 Ca + ground state is investigated. These calculations provide recommended values critically evaluated for their accuracy for a number of Ca + atomic properties for use in planning and analysis of various experiments as well as theoretical modeling. PACS numbers: 31.15.ac, 06.30.Ft, 31.15.ap, 31.15.ag

Critically evaluated theoretical energies, lifetimes, hyperfine constants, and multipole polarizabilities in {sup 87}Rb

Systematic study of Rb atomic properties is carried out using a high-precision relativistic all-order method. Excitation energies of the ns, np, nd, and nf (n{<=}10) states in neutral rubidium are evaluated. Reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for the levels up to n=8. Recommended values and estimates of their uncertainties are provided for a large number of electric-dipole transitions. Electric-dipole (5s-np, n=5-26), electric-quadrupole (5s-nd{sub j}, n=4-26), and electric-octupole (5s-nf{sub j}, n=4-26) matrix elements are calculated to obtain the ground state E1, E2, and E3 static polarizabilities. Scalar polarizabilities of the ns, np, and nd states, and tensor polarizabilities of the np{sub 3/2} and nd excited states of Rb are evaluated. The hyperfine A and B values in {sup 87}Rb are determined for the first low-lying levels up to n=9. These calculations provide recommended values critically evaluated for their accuracy for a number of Rb atomic properties useful for a variety of applications.

Calculation of parity-nonconserving amplitude and other properties of Ra+

We have calculated parity nonconserving 7s - 6d_{3/2} amplitude E_PNC in 223Ra+ using high-precision relativistic all-order method where all single and double excitations of the Dirac-Fock wave functions are included to all orders of perturbation theory. Detailed study of the uncertainty of the parity nonconserving (PNC) amplitude is carried out; additional calculations are performed to estimate some of the missing correlation corrections. A systematic study of the parity conserving atomic properties, including the calculation of the energies, transition matrix elements, lifetimes, hyperfine constants, quadrupole moments of the 6d states, as well as dipole and quadrupole ground state polarizabilities, is carried out. The results are compared with other theoretical calculations and available experimental values.

Relativistic many-body calculation of energies, lifetimes, hyperfine constants, and polarizabilities in {sup 7}Li

The excitation energies of ns, np, nd, and nf (n{<=}6) states in neutral lithium are evaluated within the framework of relativistic many-body theory. First-, second-, third-, and all-order Coulomb energies and first- and second-order Breit corrections to energies are calculated. All-order calculations of reduced matrix elements, oscillator strengths, transition rates, and lifetimes are given for levels up to n=4. Electric-dipole (2s-np), electric-quadrupole (2s-nd), and electric-octupole (2s-nf), matrix elements are evaluated to obtain the corresponding ground-state multipole polarizabilities using the sum-over-states approach. Scalar and tensor polarizabilities for the 2p{sub 1/2} and 2p{sub 3/2} states are also calculated. Magnetic-dipole hyperfine constants A are determined for low-lying levels up to n=4. The quadratic Stark shift for the (F=2 M=0){r_reversible}(F=1 M=0) ground-state hyperfine transition is found to be -0.0582 Hz/(kV/cm){sup 2}, in slight disagreement with the experimental value -0.061{+-}0.002 Hz/(kV/cm){sup 2}. Matrix elements used in evaluating polarizabilities, hyperfine constants, and the quadratic Stark shift are obtained using the all-order method.

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

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.

Development of M-shell x-ray spectroscopy and spectropolarimetry of z-pinch tungsten plasmas

The development of spectroscopic modeling of M-shell tungsten z-pinch plasma is presented. The spectral region from 3.5 to 6.5 A includes three distinct groups of transitions, and the best candidates for M-shell diagnostics are identified. Theoretical modeling is benchmarked with LLNL electron beam ion trap data produced at different energies of the electron beam and recorded by crystal spectrometers and a broadband microcalorimeter. A new high temperature plasma diagnostic tool, x-ray spectropolarimetry, is proposed to study polarization of W line emission and is illustrated using the results of x-pinch polarization-sensitive experiments. The x-ray line polarization of the prominent M-shell tungsten lines is calculated, and polarization markers are identified. The advantage of using x-pinch W wire experiments for the development of M-shell diagnostics is shown.

Excitation energies, polarizabilities, multipole transition rates, and lifetimes of ions along the francium isoelectronic sequence

Relativistic many-body perturbation theory is applied to study properties of ions of the francium isoelectronic sequence. Specifically, energies of the 7s, 7p, 6d, and 5f states of Fr-like ions with nuclear charges Z=87-100 are calculated through third order; reduced matrix elements, oscillator strengths, transition rates, and lifetimes are determined for 7s-7p, 7p-6d, and 6d-5f electric-dipole transitions; and 7s-6d, 7s-5f, and 5f{sub 5/2}-5f{sub 7/2} multipole matrix elements are evaluated to obtain the lifetimes of low-lying excited states. Moreover, for the ions Z=87-92 calculations are also carried out using the relativistic all-order single-double method, in which single and double excitations of Dirac-Fock wave functions are included to all orders in perturbation theory. With the aid of the single-double wave functions, we obtain accurate values of energies, transition rates, oscillator strengths, and the lifetimes of these six ions. Ground state scalar polarizabilities in Fr I, Ra II, Ac III, and Th IV are calculated using relativistic third-order and all-order methods. Ground state scalar polarizabilities for other Fr-like ions are calculated using a relativistic second-order method. These calculations provide a theoretical benchmark for comparison with experiment and theory.

Magic wavelengths for the 5s-18s transition in rubidium

Magic wavelengths, for which there is no differential ac Stark shift for the ground and excited state of the atom, allow trapping of excited Rydberg atoms without broadening the optical transition. This is an important tool for implementing quantum gates and other quantum information protocols with Rydberg atoms, and reliable theoretical methods to find such magic wavelengths are thus extremely useful. We use a high-precision all-order method to calculate magic wavelengths for the 5s−18s transition of rubidium, and compare the calculation to experiment by measuring the light shift for atoms held in an optical dipole trap at a range of wavelengths near a calculated magic value.

Autoionization rates for 1s2s22p2, 1s2s2p3, 1s2p4 states of B-like ions (6 < Z < 54) for decay via different channels

Two different calculational methods, MZ and AUTOLSJ, are used to obtain autoionization rates for doubly excited states 1s2s22p2, 1s2s2p3, 1s2p4 of B-like ions in a wide range of nuclear charge Z (6 ≤ Z ≤ 54). Besides the total autoionization rates decayed via channels, so-called partial rates are computed in the intermediate coupling scheme. The Z-dependences of the partial rates are investigated in detail. A comparison shows a good agreement between these two methods. These data can be used to model dielectronic satellite spectra in plasmas. In particular, amplitudes and partial rates of autoionization decay are of importance for detailed atomic kinetic calculations and for the the study of polarization properties of dielectronic satellite spectra.

Atomic Properties of Lu

Singly ionized lutetium has recently been suggested as a potential clock candidate. Here we report a joint experimental and theoretical investigation of