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Photoionization (PI) of the Ti9+ ion is investigated using the Dirac R-matrix method. Multi-configuration Dirac–Fock (MCDF) calculations are performed to construct accurate target functions. Good agreement of energy levels and radiative transition rates indicate the accuracy of target functions. PI cross sections show good consistency between length and velocity forms. The results are consistent with the previous theoretical values in high-energy regions. Partial waves' contribution to the total PI cross sections are discussed for the GS and MS. Moreover, the PI cross sections are dominated by many resonance structures and affected by the channel coupling effects in the low-energy region. In addition to providing data for the Opacity Project TOPbase, the present work promotes plasma simulation and diagnosis. [ABSTRACT FROM AUTHOR]

Hydrogen-like ions with high Z present unique opportunities to promote the understanding of atomic structure. On the other hand, determining the atomic structure of hydrogen-like atoms provides us the test of relativistic effects as well as accurate values of the spectral characteristics required for many applications. For this reason we have calculated level energies of hydrogen like thorium (Th89+, Z = 90) with both multiconfiguration Hartree-Fock (MCHF) and multiconfiguration Dirac-Fock (MCDF) methods. These calculations have contained the Breit-Pauli relativistic corrections in MCHF calculation and quantum electrodynamics effects in MCDF calculations besides electron correlations. The wavelengths, λ, weighted oscillator strengths, gf-value, and transition probabilities, Aki, have been also represented for allowed (E1) and forbidden (E2 and M1) transitions. We have compared our results with only theoretical work results because there is no available experimental data for Th89+. [ABSTRACT FROM AUTHOR]

The electric dipole transition probabilities and the oscillator strengths of neutral scandium have been calculated using the quantum defect orbital theory and the Cowan code for the 3d4s2-3d4s4p, 3d24s-3d24p, and 3d4s2-4s24p transitions. In addition, a parametric analysis of the fine structure for the 3d4s2 configuration of even parity is performed using Cowan code. The transition probabilities and the oscillator strengths obtained in this work are mostly in agreement with the data obtained from different theoretical works given in the literature. Moreover, transition probabilities for 24 levels of neutral scandium are given for the first time. [ABSTRACT FROM AUTHOR]

We report calculations of energy levels, radiative decay rates, and lifetimes for transitions among the 3s23p5, 3s3p6, and 3s23p43d configurations of Cl-like W LVIII. The general-purpose relativistic atomic structure package (GRASP) has been adopted for our calculations. Comparisons are made with the most recent results of Mohan et al. ( Can. J. Phys. 92, 177 (2014). and discrepancies in lifetimes are noted, up to four orders of magnitude in some instances. Our energy levels are estimated to be accurate to better than 0.5%, whereas results for radiative rates and lifetimes should be accurate to better than 20%. [ABSTRACT FROM AUTHOR]

The effect of temperature (20-60 °C) on the fluorescence emission of (E)-N-(3-chlorophenyl)-2-(3,4,5-trimethoxybenzylideneamino)-4,5,6,7-tetrahydrobenzo [b]thiophene-3carboxamide (ENCTTTC) is studied in different solvents. It is found that there is no shift in the position of fluorescence maxima, but the intensity decreases with increasing temperature, which depends on the polarity of the solvent. A mechanism of fluorescence quenching with rise in temperature is discussed in terms of the relative location of lowest (ππ*) (nπ*) states and the energy difference between them. The change in temperature brings about a change in the probabilities of radiative and nonradiative transition. The nonradiative deactivation of excited states in the absence of a quencher is temperature dependent and its thermal activation energy has been determined. [ABSTRACT FROM AUTHOR]

Glass samples of composition (in mol%) 20PbO-20TeO2-(60 - x)B2O3- xNd2O3 ( x = 0, 1, 2, 3, 4) were prepared by melt quenching. The glassy nature of as-quenched samples was established via differential scanning calorimetry. The amorphous nature of the glasses was confirmed via powder X-ray diffraction measurements. Judd-Ofelt (JO) analysis based on UV-visible absorption spectra was performed to determine JO parameters Ωλ ( λ = 2, 4, 6). The observed trend is Ω2 > Ω6 > Ω4. The large value of Ω2 indicates the presence of covalent bonding between the Nd3+ ions and the surrounding ligands. Radiative properties, such as radiative transition probabilities, branching ratios, and radiative lifetimes are estimated. The glass samples have relatively high branching ratio, and their emission ( Aem) to excited state absorption ( AESA) intensity ratio is higher than one for the 4F3/2 → 4I11/2 transition, indicating that the prepared glasses may have potential laser applications. [ABSTRACT FROM AUTHOR]

Energies and Auger widths of high-lying doubly-excited states 1s23 lnl′ ( n = 3-6) for Be-like neon are calculated using a saddle-point variational method and saddle-point complex-rotation method. The relativistic corrections and mass polarization are obtained with first-order perturbation theory. The configuration structure of the high-lying doubly-excited series is checked by relativistic perturbation corrections. The oscillator strengths and radiative transition probabilities are also calculated. Our results of energies and Auger widths are compared with the available theoretical results in the literature. Auger channel energies are compared with those from high-resolution electron spectroscopy. Excellent agreement is obtained in each state. [ABSTRACT FROM AUTHOR]

We present our recent progress on theoretical studies that involve auto-ionizing states of highly charged tungsten ions. Such auto-ionizing states have two channels for decay, which requires that both radiative and auto-ionization atomic data be calculated and combined in a detailed study of the dielectronic recombination (DR). Three atomic codes are used to produce relativistic atomic data (energy levels, radiative transition probabilities, and auto-ionization rates). These are the relativistic many-body perturbation theory (RMBPT) code, the multiconfiguration relativistic Hebrew University Lawrence Livermore atomic code (HULLAC), and the Hartree-Fock relativistic (Cowan) code. Branching ratios relative to the first threshold and intensity factors are calculated for satellite lines, and DR rate coefficients are determined for the excited states. The total DR rate coefficient is derived as a function of electron temperature, and it is shown that the contribution of the highly excited states is very important for the calculation of the total DR rates. Synthetic dielectronic satellite spectra are constructed, and the atomic properties specific to the relevant tungsten ions are highlighted. First, we will consider the results for Na-like tungsten (W63+) and Mg-like tungsten (W62+) using all three codes. Then, we move to even higher ionization states and present the results in Li-like W (W71+). For this we use the RMBPT code as well as the quasi-relativistic many-body perturbation theory (MZ) code. The inclusion of the DR process is essential for correct identification of the lines in impurity spectra and for understanding the main contributions to the total radiation losses. [ABSTRACT FROM AUTHOR]

Precise determination of bound-electron g-factors in highly charged ions provides stringent tests for state of the art theoretical calculations. The scope reaches from relativistic electron-correlation effects on the one hand to bound-state QED terms on the other. Besides, the investigation can contribute to the determination of the fine-structure constant α. In a first approach with boron-like ions of spinless nuclei (e.g., 40Ar13+ and 40Ca15+), we will excite the 22P1/2 - 22P3/2 fine-structure transition with laser radiation and probe microwave transitions between Zeeman sublevels. From this laser-microwave double-resonance technique the g-factor can be determined on a ppb level of accuracy. We have prepared a cryogenic trap assembly with a creation trap and a spectroscopy trap - a half-open compensated cylindrical Penning trap. Argon gas will be injected through a remotely controlled valve, working at cryogenic temperature and in the field of a superconducting magnet. Ions are produced by electron impact ionization and transferred to the spectroscopy trap. In the future, the trap will be connected to the HITRAP facility at GSI, and the method will be applied to hyperfine-structure transitions of hydrogen-like heavy ions to measure electronic and nuclear magnetic moments. We present important techniques employed in the experiment. La mesure précise du facteur de Landé d'un électron lié offre la possibilité de tester de façon rigoureuse les dernières avancées théoriques. Ces dernières peuvent s'étendre des effets relativistes dans les corrélations électroniques, aux termes d'EDQ d'état lié. Par ailleurs, de tels investigations peuvent contribuer à la détermination de la constante de structure fine, α. Dans une première partie, nous décrirons l'excitation de la transition de structure fine 22P1/2 - 22P3/2 d'ions boreoides sans spin nucléaire (e.g., argon 40Ar13+ et calcium 40Ca15+) par radiation laser, puis nous présenterons la mesure des transitions micro-ondes entre les sous-niveaux Zeeman. Grâce à cette technique de résonance double par laser et micro-ondes, le facteur de Landé peut être déterminé à un niveau de précision ppb. Nous avons préparé un montage de piège cryogénique comprenant un piège-création et un piège spectroscopique. Le gaz d'argon est injecté par l'intermédiaire d'une valve contrôlable à distance portée à des températures cryogéniques et dans le champs d'un aimant supraconducteur. Les ions sont produits par ionisation due à l'impact des électrons et transférés au piège spectroscopique. Dans le futur, le piège sera connecté au montage HITRAP, du laboratoire GSI-Darmstadt, et la méthode sera appliquée aux transitions hyperfines d'ions lourds hydrogenoides afin de mesurer les moments magnétiques électroniques et nucléaires. Nous présentons dans la suite des techniques importantes de l'expérience. [ABSTRACT FROM AUTHOR]

In this paper, a new experiment is presented to measure the 1S-2S transition of positronium, the bound state of an electron and a positron. The goal is to improve the current accuracy by a factor of 5 to reach a precision of the order of 0.6 ppb, to check recent QED calculations. This accuracy is challenging, but it seems well within reach in view of the technological advances that have occurred during the last two decades. We will present the details of the experimental set-up, the advances in the production of positronium, the developments of the laser system, and as well our new experimental technique for the detection of Ps in the 2S state. Nous présentons ici une nouvelle expérience pour mesurer la transition 1S-2S du positronium (Ps), le système lié constitué d'un électron et d'un positron. Le but est d'améliorer l'exactitude actuelle par un facteur de 5 pour atteindre une précision de 0.6 ppb afin de vérifier les récents calculs QED. Cette précision est un défi, mais semble à la portée des récents progrès technologiques atteints dans les deux dernières décennies. Nous présentons les détails du montage expérimental, les progrès dans la production de positronium, le développement du système laser, ainsi que notre nouvelle technique expérimentale pour la détection du Ps dans l'état 2S. [ABSTRACT FROM AUTHOR]

High resolution ro-vibrational spectroscopy of H2+ or HD+ can lead to a significantly improved determination of the electron to proton mass ratio me/mp if the theoretical determination of transition frequencies becomes sufficiently accurate. We report on recent theoretical progress in the description of the hyperfine structure of H2+, as well as first steps in the evaluation of radiative corrections at order mα7. Completion of the latter calculation should allow us to reach the projected 10-10 accuracy level and open the road to mass ratio determination. La spectroscopie rovibrationnelle à haute résolution de H2+ et HD+ peut mener à une amélioration significative de la valeur du rapport de masse électron-proton, me/mp, à condition d'avoir accès à des valeurs théoriques suffisamment précises des fréquences de transition. Nous présentons des progrès théoriques récents dans la description de la structure hyperfine de H2+, ainsi que les premières étapes pour évaluer les corrections radiatives à l'ordre mα7. Une fois complété, ce calcul devrait permettre d'atteindre la précision visée de 10-10, ce qui ouvrirait la porte à la détermination du rapport de masse. [ABSTRACT FROM AUTHOR]

The relativistic corrections to the theoretical oscillator strengths of light elements such as helium are typically less than 0.1% and usually are ignored. However, they can be important for comparisons with the most accurate experiments, and they rapidly increase in magnitude with increasing nuclear charge. We have begun with the spin-forbidden electric-dipole transitions of neutral helium, using calculations consisting of (1) extremely accurate wave functions without relativistic corrections for both infinite and finite nuclear mass, (2) spin-changing matrix elements through the perturbations of the wave functions by the spin-orbit and spin-other-orbit Breit operators, (3) the use of pseudostates in the sums over all the intermediate states including the continuum, and (4) the inclusion as perturbers of the 1S0 and 3S1 states the pseudostates corresponding to the doubly excited npn′p 3P0e and npn′p 1P1e terms, respectively. As examples of these calculations, we present oscillator strengths for the transitions 1 1S0-2 3P1, 2 1S0-2 3P1, 2 3S1-2 1P1, 2 1P1-3 3D1,2, and 2 3P1,2-3 1D2. Les corrections relativistes aux forces d'oscillateur théoriques d'éléments légers comme l'hélium sont typiquement plus petites que 0.1% et sont généralement ignorées. Cependant, elles peuvent être importantes pour comparer avec les valeurs expérimentales les plus précises et elles augmentent rapidement avec la charge nucléaire. Nous débutons avec les transitions dipolaires électriques spin interdites dans l'hélium neutre, à l'aide de calculs qui reposent sur, (1) des fonctions d'onde extrêmement précises sans correction relativiste pour des masses nucléaires infinies et finies, (2) des éléments de matrice de changements de spin via les perturbations de la fonction d'onde causées par les opérateurs de Breit de spin-orbite et de spin-autre orbite, (3) l'utilisation de pseudo états dans la somme sur tous les états intermédiaires, incluant le continuum et (4) l'introduction, comme agents perturbant les états 1S0 et 3S1, des pseudo états correspondant aux termes doublement excités npn′p 3P0e et npn′p 3P1e respectivement. Comme exemples de nos calculs, nous présentons les forces d'oscillateur pour les transitions 1 1S0-2 3P1, 2 1S0-2 3P1, 2 3S1-2 1P1, 2 1P1-3 3D1,2 et 2 3P1,2-3 1D2. [ABSTRACT FROM AUTHOR]

The ASACUSA collaboration at CERN has previously measured the optical transition frequencies of antiprotonic helium to a precision of <1 part in 108 by laser spectroscopy. We describe some recent theoretical and experimental developmental work carried out by our collaboration to further improve the experimental precision. Utilisant la spectroscopie laser, la collaboration ASACUSA au CERN a déjà mesuré les fréquences de transition optique de l'hélium antiprotonique à mieux qu'une partie dans 108. Nous décrivons des travaux récents, théoriques et expérimentaux, effectués par nos collaborateurs, afin d'améliorer la précision expérimentale. [ABSTRACT FROM AUTHOR]

We describe a complete software package for the computation of various atomic data such as energy levels; radiative transition; collisional excitation; ionization by electron impact, photoionization, autoionization; and their inverse processes radiative recombination and dielectronic capture. The atomic theoretical background and numerical techniques associated with each process are discussed in detail. Sample applications and results are presented. PACS Nos.: 31.15.–p, 32.70.Cs, 34.80.Kw, 32.80.Fb, 32.80.Dz [ABSTRACT FROM AUTHOR]

Wavelengths, transition rates, and line strengths are calculated for the 85 possible multipole transitions between the excited 4p6 4d9 4f, 4p6 4d9 5l, 4p5 4d10 4f, and 4p5 4d10 5l states and the ground 4p6 4d10 state in Pd-like ions with the nuclear charges ranging from Z = 47 to 100. Relativistic many-body perturbation theory (RMBPT), including the Breit interaction, is used to evaluate energies and transition rates for multipole transitions in hole–particle systems. This method is based on the relativistic many-body perturbation theory, agrees with MCDF calculations in lowest order, includes all second-order correlation corrections, and includes corrections from negative energy states. The calculations start from a [Zn]4p64d10 Dirac–Fock potential. First-order perturbation theory is used to obtain intermediate-coupling coefficients, and second-order RMBPT is used to determine the matrix elements. The contributions from negative-energy states are included in the second-order multipole matrix elements. The resulting transition energies and transition rates are compared with experimental values and with results from other recent calculations. Trends of the transitions rates for the selected multipole transitions as function of Z are illustrated graphically. The Z dependence of the energy splitting for all triplet terms of the 4p64d9 4f and 4p64d9 5l configurations are shown for Z = 47–100. PACS Nos.: 31.15.Ar, 31.15.Md, 32.70.Cs, 32.30.Rj, 31.25.Jf [ABSTRACT FROM AUTHOR]

We report on our recent advances in the calculation of the energy levels of the H+2 molecular ion, including relativistic and radiative corrections. These theoretical efforts are linked to the prospect of obtaining a new determination of the proton to electron mass ratio mp/me through precise vibrational spectroscopy of H+2. We describe the setup of our experiment, aiming at a measurement of the L = 2, υ = 0 → L = 2, υ = 1 two-photon transition at 9.166 μm using a phase-locked quantum cascade laser as excitation source.PACS Nos.: 31.15.Pf, 31.30.Jv, 32.10.Hq [ABSTRACT FROM AUTHOR]

We consider three-loop radiative corrections to the Lamb shift and hyperfine splitting. Corrections of order α3(Zα)5m are the largest still unknown contributions to the Lamb shift in hydrogen. We calculate radiative corrections to the Lamb shift and hyperfine splitting generated by the diagrams with insertions of one radiative photon and electron polarization loops in the graphs with two external photons. We also obtain corrections generated by the gauge-invariant sets of diagrams with two reducible radiative photon insertions in the electron line and a polarization operator insertion in one of the radiative photons, and diagrams with two reducible radiative photon insertions in the electron line and a polarization operator insertion in one of the external photons. Corrections to the Lamb shift and hyperfine splitting generated by the diagrams with insertions of the three-loop one-particle reducible diagrams with radiative photons in the electron line are calculated in the Yennie gauge.PACS Nos.: 12.20.Ds, 31.30.Jv, 32.10.Fn, 36.10.Dr [ABSTRACT FROM AUTHOR]

We measured the spontaneous-emission branching ratios of 69 levels in Sm II selectively populated via single-frequency laser excitation of a 10 keV ion beam. The levels studied had term energies up to 29 600 cm–1, and decay branches with spontaneous emission in the range 250–850 nm were detected. The experimental accuracy was in the range of 10%. We used these branching ratios along with our previously determined radiative lifetimes to infer transition probabilities and oscillator strengths for 608 transitions in the wavelength range 363–771 nm, which are useful for stellar abundance determinations.PACS Nos.: 32.70.Cs, 95.30.Ky [ABSTRACT FROM AUTHOR]

We summarize our study of a diatomic homonuclear molecule incident upon a potential barrier in one dimension [G.L. Goodvin and M.R.A. Shegelski. Phys. Rev. A, 71, 032719 (2005).]. We study various initial states for the molecule and allow transitions between vibrational states of the molecule during the process of tunneling. By applying an elegant method to solve this problem, we show that transmission resonances occur in several cases and that adding more binding energy levels for the molecule can tend to decrease the probability of tunneling. We also discuss the extension of our results to more realistic three-dimensional and experimental systems.PACS Nos.: 34.20.Cf, 03.65.Xp, 34.20.Gj, 34.50.Pi [ABSTRACT FROM AUTHOR]

Multicharged Xe ions following de-excitation of K-, L1-, L2,3-, M1-, M2,3-, and M4,5-subshell vacancies are calculated using a Monte-Carlo algorithm to simulate the vacancy cascade development. Fluorescence yield (radiative) and Auger and Coster–Kronig yields (nonradiative) are evaluated. The decay of the K hole state through radiative transitions is found to be more probable than through nonradiative transitions in the first step of de-excitation. On the other hand, the decay of L and M vacancies through nonradiative transitions are more probable. Ions, mainly produced from Xe in the K-shell vacancy state, are found to be Xe7+, Xe8+, Xe9+, and Xe10+. The charged Xe8+ ions predominate in the charge state distributions. The main product from the L1-shell ionization is found to be Xe8+ and Xe9+ ions, while the Xe8+ ions predominate at the L2,3 hole states. The charged Xe6+, Xe7+, and Xe8+ ions come mainly from 3s1/2 and 3p1/2,3/2 ionization, while Xe in 3d3/2,5/2 hole states becomes mainly Xe4+ and Xe5+ ions. The present results are found to agree well with the experimental data.PACS No.: 32.40.Hd [ABSTRACT FROM AUTHOR]

A quasipotential method is formulated for calculating relativistic and radiative corrections to the magnetic moment of a two-particle bound state in the case of particles with arbitrary spin. It is shown that the g factors of bound particles contain O(α[sup 2] ) terms depending on the particle spin. Numerical values for the g factors of the electron in the hydrogen atom and deuterium are obtained. PACS Nos.: 31.30Jv, 12.20Ds, 32.10DkNous développons une méthode avec quasipotentiel pour calculer les corrections relativistes et radiatives au moment magnétique d'un état de deux particules liées de spin arbitraire. Nous montrons que le facteur g des particules liées contient des corrections à l'ordre O(α[sup 2] ) dépendant du spin de la particule. Nous obtenons des résultats numériques pour le facteur g de l'électron dans des atomes d'hydrogène et de deutérium.[Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]

In this study, we combine the classical models of the massive and massless spinning particles, derive the current-current interaction Lagrangian of the particles from the gauge transformations of the classical spinors, and discuss radiative processes in electrodynamics by using the solutions of the Dirac equation and the quantum wave equations of the photon. The longitudinal-polarized photon states give a new idea about the vacuum concept in electrodynamics. [ABSTRACT FROM AUTHOR]

Radiative transition probabilities for 190 lines arising from the ns [sup 2] S[sub 1/2] , np [sup 2] P[sub 1/2,3/2] , nd [sup 2] D[sub 3/2,5/2] , nf [sup 2] F[sub 5/2,7/2] , and 6p[sup 2] ([sup 4] P[sub 1/2,3/2,5/2] , [sup 2] D[sub 3/2,5/2] , [sup 2] P[sub 1/2,3/2] , and [sup 2] S[sub 1/2] ) levels of Pb(II) have been calculated. Lifetimes of the above mentioned levels have been determined from the present transition probabilities. These values were obtained in intermediate coupling (IC) and using ab initio relativistic Hartree-Fock calculations. For the IC calculations, we use the standard method of least-square fitting of experimental energy levels by means of computer codes from Cowan. The results of calculations for radiative transition probabilities and excited states lifetimes are presented and compared with the experimental results present in the literature and with other theoretical values. There is generally good agreement between our values and the experimental data available. Analysis of the interaction shows that the level [sup 4] P[sub 5/2] of the 6s6p[sup 2] configuration presents a large contribution to the [sup 2] D[sub 5/2] level of the 6s[sup 2] 6d configuration. This result explains the good agreement between our result and the experimental values obtained to the observed as the 6s6p[sup 2 4] P[sub 5/2] – 6s [sup 2] 5f[sup 2] F[sub 7/2] dipole-forbidden transition. PACS Nos.: 32.70^*, 32.70Fw, 32.70CsNous avons calculé les probabilités de transition radiative provenant des niveaux de Pb(II) ns [sup 2] S[sub 1/2] , np [sup 2] P[sub 1/2,3/2] , nd [sup 2] D[sub 3/2,5/2] , nf [sup 2] F[sub 5/2,7/2] et 6p[sup 2] ([sup 4] P[sub 1/2,3/2,5/2] , [sup 2] D[sub 3/2,5/2] , [sup 2] P[sub 1/2,3/2] et [sup 2] S[sub 1/2] ). Les demi-vies sont évaluées à partir de ces probabilités. Les valeurs numériques ont été obtenues de deux façons, utilisant l'approche du couplage intermédiaire (I.C.) et un calcul Hartree-Fock relativiste complet. En I.C., nous utilisons l'approche habituelle d'ajustement moindre carré des niveaux à des valeurs expérimentales en utilisant le programme de Cowan. Les résultats des calculs sont comparés aux valeurs expérimentales trouvée dans la littérature scientifique ainsi qu'à d'autres valeurs théoriques. L'accord est généralement très bon entre nos résultats et les valeurs expérimentales. Une analyse des interactions montre que le niveau [sup 4] P[sub 5/2] de la configuration 6s6p[sup 2] a une contribution importante du niveau [sup 2] D[sub 5/2] de la configuration 6s[sup 2] 6d. Ce résultat explique le bon accord entre nos résultats et les valeurs expérimentales pour la transition dipolaire interdite 6s6p[sup 2 4] 4P[sub 5/2] – 6s [sup 2] 5f[sup 2] F[sub 7/2] . [Traduit par la Rédaction] [ABSTRACT FROM AUTHOR]