[en] The spectrum of xenon injected into the TFR tokamak plasma has been recorded in the range 10-90 A by means of a 2m grazing incidence spectrograph. Forty-four lines and unresolved transition arrays pertaining to multicharged xenon ions isoelectronic with Cu I, Ni I, Co I, Fe I, Mn I and Cr I have been identified by means of various theoretical methods. The 17 observed lines of the 3p⁶3d⁸ - 3p⁵3d⁹ transition array, have allowed the wavelengths of the magnetic dipole transitions occuring within the ground configuration 3d⁸ of Xe XXXIX to be predicted

[en] A complete quasi-hydrogenic diamagnetic manifold is experimentally investigated. The spectra are obtained in a uniform magnetic field by exciting M = O odd Rydberg states of lithium in a one-step process. This experiment provides an experimental confirmation for the existence of the two classes of states previously predicted for the diamagnetic Hamiltonian of atomic hydrogen. The evolution of the structure of the n = 30 M = O manifold of lithium under the influence of an additional electric field parallel to the magnetic field is also investigated. The three experimentally observed classes of states are related to the existence and properties of the approximate integral of motion valid for the hydrogen atom in the presence of weak parallel electric and magnetic fields. Significant alterations present in the lithium spectra are ascribed to the nonhydrogenic character of the s states. 9 references

[en] Theoretical energy-positions of 4fnf J=5,6 autoionising levels of barium are obtained by a combination of the eigenchannel R-matrix and the Multichannel Quantum Defect Theory (MQDT) methods. High-lying 4fnf J=5,6 levels (n>8) located below the Ba⁺4f_5/2 threshold are investigated. The calculation accounts for the mixing of 4fnf series with 4fnp and 7pnf series, as well as for the interaction with thirty continua. Calculated energies agree well with recent measurements obtained in a two-step laser experiment. Strong mixing between 4f_5/2nf_7/2 and 4f_7/2nf_5/2 series is found, while the 4f_5/2nf_5/2 series are almost pure jj-coupled. Because of strong centrifugal barrier and two-electron correlation effects, the 4fnf series have large quantum defects depending strongly on the series studied. (orig.)

No abstract available

[en] Spectroscopic data for highly ionised atoms are discussed within given isoelectronic sequences as a function of the nuclear charge. The systematic trends result from the relative influence of correlations and relativistic effects. Satellite lines associated with dielectronic recombination, forbidden transitions and unresolved transition arrays and their applications for plasma diagnostics are also presented

[en] We focus on the theoretical modelling of the dynamics of ion-neutral systems at ultracold temperatures (<< 1K) in order to design ways for their full quantum control. Our aims are connected to experimental investigations of alkaline earth ion - alkali atom systems with hybrid traps. Due to the laser cooling scheme a metastable d-level of the alkaline-earth ion is considerably populated in these experiments, e.g. in case of 88Sr+ ion embedded in the cloud of ultracold 87Rb atoms [1] or 138Ba+ in 6Li cloud [2]. The large internal energy of the ion induces several inelastic processes like charge-exchange, spin-orbit change collisions or electronic excitation exchange. We compute cross sections and rate coefficients for these processes within the framework of the quantum coupled-channel model considering the fine-structure of the colliding partners and the rotational coupling. Our calculations involve potential energy curves including the determination of R-dependent spin-orbit couplings (see Figs. 1, 2) following a diabatization approach [3]. Fig.1: Selected Hund's case (a) LiBa+ potential energy curves in the molecular frame. The red shadow shows the location of an avoided crossing of 21 Σ and 31 Σ responsible of the non-radiative charge exchange (NRCE) process (red arrow): Li(2s)+Ba+(5d) → Li++Ba(6s2,1S) . Fig.2: The R-dependent spin-orbit couplings of the first 3 dissociation limits, based on Ω=0+/-, 1, 2, 3 the projection of the total angular momentum on molecular axis. [1] R. Ben-Shlomi, R. Vexiau, Z. Meir, T. Sikorsky, N. Akerman, M. Pinkas, O. Dulieu, R. Ozeri, Phys. Rev. A 102 ,031301(R) [2] P. Weckesser, F. Thielemann, D. Wiater, A. Wojciechowska, L. Karpa, K.Jachymski, M. Tomza, T. Walker, T. Schaetz, Nature 600, 429 (2021) [3] X. Xing, R. Vexiau, N. Bouloufa, O. Dulieu et al, in preparation. We acknowledge support from the CRNS International Emerging Action (IEA) - ELKH, 2023-2024; Program Hubert Curien ”BALATON” (CampusFranceGrantNo.49848TC)–NKFIHTE ́T-FR(2023-2024)

[en] Absolute values for the density of oscillator strengths in the photoabsorption spectrum of hydrogen-like atoms in the presence of a uniform electric field are calculated using the wavefunctions obtained from the method described in a previous paper (J. Phys. B.; 13: 1743 (1980)). The symmetry properties of the wavefunctions with respect to the plane z=0 are analysed - z is the direction of the electric field. Cancellation effects can appear in the calculation of oscillator strengths due to the symmetry properties of the wavefunctions and of the polarisation of the light. The hydrogenic model is used to interpret the structures observed in the absorption spectra of alkali atoms and of semiconductors in the presence of an external electric field. (author)

[en] It is shown that the separation usually made between wavefunction effects and operator effects in the calculation of relativistic corrections is not unique. Some remarks are made about the different ways of introducing relativistic corrections to wavefunctions. (author)

[en] An exact method of obtaining normalised wavefunctions for a hydrogen-like atom in the presence of a uniform electric field is reported. An unambiguous classification of the Stark state is presented which correlates a given Stark state to a unique zero-field state; this classification is valid for any Stark states - resonant or non-resonant - and at any energy smaller or greater than E₀ the ionisation limit of the unperturbed atom. From the supersymmetry in the hydrogen spectrum, states with different values for m, the magnetic quantum number, or for n₁, the generalised parabolic quantum number, can be considered independently. A parabolic critical energy can be defined for any state m, n₁; for sufficiently high value of n₁ the critical energy is greater than E₀. A systematic study of the positions and widths of the resonances in a broad energy range below E₀ is presented. (author)

[en] Oscillator strengths for electric dipole transitions within the ground complex of the aluminium isoelectronic sequence have been calculated up to Np⁸⁰⁺ using the relativistic parametric potential method. The electrostatic interaction between all states of the complex is explicitly introduced. The Z dependence of the f values throughout the sequence is analysed for the particular example of transitions between the odd levels J = 1/2 and the even levels J = 3/2. (author)