Angular distributions for photo-double-ionization of the He isoelectronic sequence

We describe the three-body final state resulting from the photo-double-ionization (PDI) of two-electron ionic atoms by a modified C3 wave, denoted SC3. This continuum wave function accounts for the nuclear dynamical screening in the inter-electronic motion. We analyze the scaling properties of the triply differential cross-sections (TDCS). For an easier comparison with possible experimental results we analyze the correlation factor in the Gaussian parametrization of the TDCS, for different nuclear charges. We determine the dependence of the half width at half maximum of the Gaussian with the nuclear charge and discuss possible physical mechanisms.Received: 14 July 2003, Published online: 16 September 2003PACS: 32.80.Fb Photoionization of atoms and ions     

Contribution of the magnetic dipole transition in the Be isoelectronic sequence

The 1s²2s2p J = 2 → J = 1 M1 transition rates are calculated in the multi-configuration Hartree-Fock procedure for several members of the beryllium isoelectronic sequence. The total transition rates, including existing M2 rates, are presented for different atomic numbers.     

Probabilities of electric dipole transitions in the spectra of ions of the erbium isoelectronic sequence

The probabilities of the 4f ¹³6p→4f ¹³ ns (n=6 and 7) electric dipole transitions are calculated for the spectra of YbIII, LuIV, and HfV ions of the erbium isoelectronic sequence. The wave functions of the intermediate coupling scheme, which are necessary for calculating the relative line strengths, are semiempirically obtained from experimentally measured energy intervals between the fine-structure levels. To pass to the absolute values, radial integrals of transitions are used, which are evaluated with the Hartree-Fock functions.     

Relativistic radiative transition rates and energies for the Li-like isoelectronic sequence: Electric and magnetic dipole and quadropole radiation

For Li-like ions in the isoelectronic sequence between the nuclear charges Z = 26 and 94, energies, oscillator strengths and probabilities of electric and magnetic dipole and quadropole transitions between the first 22 atomic levels were calculated by means of the multiconfigurational Dirac-Fock model. The effects of nonlocal Breit interaction, electron self-energy and vacuum polarization were included in calculating energy levels and radiative rates. The trends of transition energies and rates along the isoelectronic sequence, in particular, the enhancement of the forbidden transitions with increasing atomic number Z, are discussed.     

Excitation of the Li isoelectronic sequence

Summary The inner-shell excitation 1s ²2s ² S ^e→1s2s ²² S ^e, which leads to autoionization (Auger transition), as well as the outer-shell excitation 1s ²2s ² S ^e→ 1s ²2p ² P ⁰ transitions have been investigated in Li, Be⁺, B²⁺ and C³⁺ ions of the lithium isoelectronic sequence employing the configuration interaction wave functions for both the initial and final states involved in the transition matrix element. Results are compared with other available theoretical predictions and experimental observations. Comparison shows that our present theoretical results are encouraging. A part of this work was done while the author was Research Director and Professor, CNRS Laboratory, University of Paris-Sud, Paris and Observatoire de Paris, Meudon, Paris, France.     

Semiempirical law for the dipole moments of low-molecular-weight gelators

Some small chiral organic molecules are capable of forming gel in low-concentration solutions. This phenomenon is of great theoretical interest, but its molecular details are still unclear. High chemical diversity of such gelators impedes the investigation of their common structural properties important for gel formation. Here, we calculated the total dipole moment for a set of gelators with sufficiently different chemical structures by means of molecular dynamics simulations. It was found that all considered molecules have a dipole moment of ～3 D or more. This means that the energy of the dipole-dipole interaction between two point dipoles at a distance of 6–8 Å is ～kT. This distance roughly corresponds to molecules in close contact. This makes it possible to conclude that the dipole moment can orient gelator molecules before aggregation, thereby playing a key role in the process of gelation. This orientation effect determines the anisotropy of aggregates and the gelation of the solution.     

Additional stringy sources for electric dipole moments

We show that string models with low energy supersymmetry which accommodate the fermion mass hierarchy generally give nonuniversal soft trilinear couplings (A terms). In conjunction with the apparently large Cabibbo-Kobayashi-Maskawa (CKM) phase, this results in large fermion electric dipole moments (EDMs) even in the absence of CP violating phases in the supersymmetry breaking auxiliary fields and the micro term. Nonobservation of the EDMs therefore implies that strings select special flavor and/or supersymmetry breaking patterns.     

Search for electric dipole moments at storage rings

Twenty years ago, we published a paper entitled “Discovery of antiproton trapping by long-lived metastable states in liquid helium”. In retrospect, this was the discovery of antiprotonic helium atoms, the study of which is actively being done at CERN’s antiproton decelerator. A brief overview of this interesting exotic atom is given, together with some historical background.     

Oscillator strengths for 2 transitions of the lithium isoelectronic sequence

The nonrelativistic dipole-length, -velocity and -acceleration absorption oscillator strengths for the 1s²2s-1s²np (3 ￡ n ￡ 9)(3\leq n\leq 9) transitions of the lithium isoelectronic sequence up to Z=10 are calculated by using the energies and the multiconfiguration interaction wave functions obtained from a full core plus correlation (FCPC) method. In most cases, the agreement between the f-values from the length and velocity formulae is up to forth or fifth digit. Combining these discrete oscillator strengths with the single channel quantum defect theory (QDT), the discrete oscillator strengths for the transitions from the 1s^22s state to highly excited levels (n 3 10n \geq 10) and the oscillator strength densities corresponding to the bound-free transitions are obtained.     

Intercombination transitions of the carbon-like isoelectronic sequence

Energy levels, wavelengths, transition rates, oscillator strengths, and lifetimes between the 2s22p23P1,2s22p23P2,and 2s2p35S2 levels of ions in the carbon-like (C-like) isoelectronic sequence (nuclear charges Z=7-92) are calculated in the valence and core-valence limits using the multiconfiguration Dirac-Fock method. The Breit interaction, quantum electrodynamics (QED), and finite nuclear mass effects are taken into account in subsequent relativistic configuration-interaction calculations. The calculated energies and transition rates are compared with the critically evaluated experimental values and other recent calculated results. Our calculated data are in good agreement with these data.     

Oscillator strengths in the boron isoelectronic sequence

The quantum defect orbital formalism in both its relativistic and non-relativistic versions has been applied to the calculation of oscillator strengths in the sharp spectral series of some boron-like systems. The results are presented in both tabular and graphical forms.     

Comment on the critical dipole moments for electron binding to a freely rotating electric dipole

In this paper the reference hypernetted-chain (RHNC) theory is solved for fluids of Stockmayer (dipolar Lennard-Jones) particles and detailed comparisons are made with computer simulation results. It is shown that the RHNC approximation significantly improves upon integral equation theories previously solved for Stockmayer systems. In particular the static dielectric constants obtained are in much better agreement with the computer simulations.     

Kinetics of dipole moments of polyatomic molecules

The relations that link the time dependences of the dipole moments of the ground and excited states of a molecular system whose charge distribution is nonstationary with the correlation functions of the shift of the absorption and emission spectra of this system are derived on the basis of of the well-known equations of solvatochromism. The calculated dependences of the kinetics of the dipole moments of the excited singlet states of dimethylaminobenzonitrile and 4-dimethylamino-4′-cyanostilbene in some polar solvents are presented.     

Leptonic dipole moments in the left-right supersymmetric model

The observation of neutrino oscillations imposes a pattern of mixing in both the sneutrino and charged slepton sectors. On the other hand, the apparent 2.6 deviation of the anomalous magnetic moment of the muon from the standard model value favors a scenario beyond the standard model. We show that, in a supersymmetric model with left-right symmetry, which provides an explanation for both phenomena, the relationship between flavor conserving dipole moments, such as the magnetic and the electric dipole moments, and flavor violating dipole moments, such as and , is quite different from that in the MSSM. From general analytic considerations, we derive bounds on the fractional sneutrino mass splittings , and the fractional charged slepton splittings . For , the mixing is allowed to be maximal. We also comment on the magnitudes and correlations between CP-violating angles coming from electric dipole moments. We supplement the analytical considerations by detailed numerical calculations. Received: 6 September 2001 / Revised version: 30 October 2001 / Published online: 7 December 2001     

Nuclear electric dipole moment of He

A permanent electric dipole moment (EDM) of a physical system requires time-reversal (T) and parity (P) violation. Experimental programs are currently pushing the limits on EDMs in atoms, nuclei, and the neutron to regimes of fundamental theoretical interest. Here we calculate the magnitude of the P-, T-violating EDM of ³He and the expected sensitivity of such a measurement to the underlying P-, T-violating interactions. Assuming that the coupling constants are of comparable magnitude for π-, ρ-, and ω-exchanges, we find that the pion-exchange contribution dominates. Our results suggest that a measurement of the ³He EDM is complementary to the planned neutron and deuteron experiments, and could provide a powerful constraint for the theoretical models of the pion–nucleon P-, T-violating interaction.