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  • 1.
    Andersson, Martin
    et al.
    Shanghai EBIT Laboratory, Institute of Modern Physics, Fudan University, Shanghai, People's Republic of China; The Key Laboratory of Applied Ion Beam Physics, Ministry of Education, People's Republic of China.
    Lennartsson, Thomas
    Department of Astronomy, Lund University, Sweden.
    Nilsson, Hampus
    Department of Astronomy, Lund University, Sweden.
    Chen, Chongyang
    Shanghai EBIT Laboratory, Institute of Modern Physics, Fudan University, Shanghai, People's Republic of China 2 The Key Laboratory of Applied Ion Beam Physics, Ministry of Education, People's Republic of China.
    The anomalous hyperfine structure of Al II2012In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 45, no 13, p. 135001-135001Article in journal (Refereed)
    Abstract [en]

    The hyperfine structure of a large number of transitions in Al II cannot be described using A and B hyperfine constants and the hyperfine structure is therefore said to be anomalous. In this paper, we have studied the hyperfine structure of a few transitions in Al II, 3s5s3S–3s5p3P, 3s4d3D–3s5p3P and 3s5p3P–3s5d3D, by combining theory and experiment. It is shown that the anomalous hyperfine structure is due to strong off-diagonal hyperfine interaction resulting not only in a deplacement of the energies of the hyperfine levels, but also resulting in large intensity redistribution among the individual hyperfine lines. It is shown that the hyperfine mixing in 3s4d3D and 3s5d3D is very large, whereas small but not negligible in 3s5p3P. By combining experimental spectra and theory we could obtain accurate wavefunctions for the 3s4d3D and 3s5d3D hyperfine levels which were used to calculate the gf-values of all individual hyperfine transitions not only for 3s5p3P, but also for 3s3p3P and 3s4p3P, where the off-diagonal hyperfine interaction leads to negligible intensity redistribution.

  • 2. Atalay, B.
    et al.
    Brage, T.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Hartman, Henrik
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    MCDHF and RCI calculations of energy levels, lifetimes, and transition rates in Si III and Si IV2019In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, ISSN 0004-6361, Vol. 631, article id A29Article in journal (Refereed)
    Abstract [en]

    We present extensive multiconfiguration Dirac-Hartree-Fock and relativistic configuration interaction calculations including 106 states in doubly ionized silicon (Si III) and 45 states in triply ionized silicon (Si IV), which are important for astrophysical determination of plasma properties in different objects. These calculations represents an important extension and improvement of earlier calculations especially for Si III. The calculations are in good agreement with available experiments for excitation energies, transition properties, and lifetimes. Important deviations from the NIST-database for a selection of perturbed Rydberg series are discussed in detail.

  • 3.
    Atalay, B.
    et al.
    Division of Mathematical Physics, Department of Physics, Lund University, LundSE-22100, Sweden; Department of Physics, Çanakkale Onsekiz Mart University, Çanakkale17100, Turkey.
    Jönsson, P.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Brage, T.
    Division of Mathematical Physics, Department of Physics, Lund University, LundSE-22100, Sweden.
    Extended relativistic multiconfiguration calculations of energy levels and transition properties in singly ionized tin2023In: Journal of Quantitative Spectroscopy and Radiative Transfer, ISSN 0022-4073, E-ISSN 1879-1352, Vol. 294, p. 108392-108392, article id 108392Article in journal (Refereed)
    Abstract [en]

    Multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) calculations are performed for 22 states in singly ionized tin (Sn II) belonging to the 5s2ns (n=6,7), 5s2nd (n=5,6), 5s5p2 even parity configurations and the 5s2np (n=5,6,7), 5s24f odd parity configurations. Valence-valence and core-valence correlation effects are taken into account through configuration state function (CSF) expansions. Complete and consistent data sets of level energies, wavelengths, oscillator strengths, lifetimes and transition rates among all these states are given. The results are compared with existing theoretical and experimental results. There is an excellent agreement for calculated excitation energies with experimental data from the NIST database. Lifetimes and transition rates are also in agreement with the results from previous calculations and available measurements for most of the transitions.

  • 4.
    Bieron, Jacek
    et al.
    Uniwersytet Jagiellonski, Inst Fizyki Teoret, PL-30348 Krakow, Poland..
    Fischer, Charlotte Froese
    Univ British Columbia, Dept Comp Sci, Vancouver, BC V6T 1Z4, Canada..
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Editorial of the Special Issue "General Relativistic Atomic Structure Program-GRASP"2023In: Atoms, E-ISSN 2218-2004, Vol. 11, no 6, article id 93Article in journal (Other academic)
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  • 5. Bieron, Jacek
    et al.
    Froese Fischer, Charlotte
    Indelicato, Paul
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Pyykkö, Pekka
    Complete Active Space multiconfiguration Dirac-Hartree-Fock calculations of hyperfine structure constants2009Conference paper (Other academic)
  • 6. Bieron, Jacek
    et al.
    Froese Fischer, Charlotte
    Indelicato, Paul
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Pyykkö, Pekka
    Complete-active-space multiconfiguration Dirac-Hartree-Fock calculations of hyperfine-structure constants of the gold atom2009In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 79, no 5, article id 052502Article in journal (Refereed)
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  • 7. Bieron, Jacek
    et al.
    Froese Fischer, Charlotte
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Pykköö, Pekka
    Comment on the magnetic dipole hyperfine interaction in the gold atom ground state2008In: Journal of Physics B : Atomic, Molecular and Optical Physics, Vol. 41, no 11, article id 115002Article in journal (Refereed)
    Abstract [en]

    The multiconfiguration Dirac–Hartree–Fock (MCDHF) model has been employed to calculate the magnetic dipole hyperfine constant A of the 5d106s 2S1/2 ground state of atomic gold. Electron correlation effects contribute more than 20% to the total value of A. We investigated the effects of single, double, and a subset of triple substitutions. The calculations reveal strong cancellations between one-, two- and three-particle correlation effects. It is demonstrated that in the case of the ground state of atomic gold the three-particle effects are comparable in size to the one- and two-particle ones.

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  • 8. Bieron, Jacek
    et al.
    Gaigalas, Gediminas
    Gaidamauskas, Erikas
    Fritzsche, Stephan
    Indelicato, Paul
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Multiconfiguration Dirac-Hartree-Fock calculations of the electric dipole moment of radium induced by the nuclear Schiff moment2009In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 80, no 1, article id 012513Article in journal (Refereed)
    Abstract [en]

    The multiconfiguration Dirac-Hartree-Fock theory has been employed to calculate the electric dipole moment of the 7s6d 3D2 state of radium induced by the nuclear Schiff moment. The results are dominated by valence and core-valence electron correlation effects. We show that the correlation effects can be evaluated in a converged series of multiconfiguration expansions.

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  • 9.
    Biémont, É.
    et al.
    Astrophysique et Spectroscopie, Université de Mons - UMONS, B-7000 Mons, 20 Place du Parc, Belgium; IPNAS (Bât. B 15), Université de Liège, Sart-Tilman, B-4000 Liège 1, Belgium.
    Blagoev, K.
    Institute of Solid State Physics, Bulgarian Academy of Sciences, Chaussee, BG-1784 Sofia, 72 Tzarigradsko, Bulgaria.
    Engström, L.
    Department of Physics, Lund University, S-221 00 Lund, PO Box 118, Sweden.
    Hartman, H.
    Lund Observatory, Lund University, S-221 00 Lund, PO Box 43, Sweden.
    Lundberg, H.
    Department of Physics, Lund University, S-221 00 Lund, PO Box 118, Sweden.
    Malcheva, G.
    Institute of Solid State Physics, Bulgarian Academy of Sciences, Chaussee, BG-1784 Sofia, 72 Tzarigradsko, Bulgaria.
    Nilsson, H.
    Lund Observatory, Lund University, S-221 00 Lund, PO Box 43, Sweden.
    Whitehead, R. Blackwell
    Lund Observatory, Lund University, S-221 00 Lund, PO Box 43, Sweden.
    Palmeri, P.
    Astrophysique et Spectroscopie, Université de Mons - UMONS, B-7000 Mons, 20 Place du Parc, Belgium.
    Quinet, P.
    Astrophysique et Spectroscopie, Université de Mons - UMONS, B-7000 Mons, 20 Place du Parc, Belgium; IPNAS (Bât. B 15), Université de Liège, Sart-Tilman, B-4000 Liège 1, Belgium.
    Lifetime measurements and calculations in Y+ and Y2+ ions2011In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 414, no 4, p. 3350-3359Article in journal (Refereed)
    Abstract [en]

    We report a new set oftheoretical transition probabilities in Yii, obtained using a multiconfiguration relativistic Hartree-Fock method including core polarization. The overall quality of the calculations is assessed by comparisons with new and previous lifetime measurements. In this paper, we report new measurements of five lifetimes in the 4d5p and 5s5p configurations, in the energy range of 32048-44569 cm-1, obtained by the time-resolved laser-induced fluorescence method. A similar theoretical model, applied to Yiii, leads to results in good agreement with new laser measurements of two 5p levels obtained in this work and with previous beam-foil results for 5d and 6s levels. An extensive set of oscillator strengths is also proposed for Yiii.

  • 10.
    Blackwell-Whitehead, R.
    et al.
    Lund Observatory, Box 43, 221 00 Lund, Sweden; Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
    Pavlenko, Y. V.
    Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK; Main Astronomical Observatory of the Academy of Sciences of Ukraine, Zabolotnoho 27, Kyiv 03680, Ukraine.
    Nave, G.
    Atomic Physics Division, National Institute of Standards and Technology, 100 Bureau Dr., Gaithersburg, MD 20899, USA.
    Pickering, J. C.
    Blackett Laboratory, Imperial College London, London SW7 2AZ, UK.
    Jones, H. R. A.
    Centre for Astrophysics Research, University of Hertfordshire, College Lane, Hatfield, Hertfordshire AL10 9AB, UK.
    Lyubchik, Y.
    Main Astronomical Observatory of the Academy of Sciences of Ukraine, Zabolotnoho 27, Kyiv 03680, Ukraine.
    Nilsson, Hampus
    Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Infrared Mn i laboratory oscillator strengths for the study of late type stars and ultracool dwarfs2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 525, p. A44-A44Article in journal (Refereed)
    Abstract [en]

    Aims. The aim of our new laboratory measurements is to measure accurate absolute oscillator strengths for neutral manganese transitions in the infrared needed for the study of late-type stars and ultracool dwarfs.

    Methods. Branching fractions have been measured by high resolution Fourier transform spectroscopy and combined with radiative level lifetimes in the literature to yield oscillator strengths.

    Results. We present experimental oscillator strengths for 20 Mn I transitions in the wavelength range 3216 to 13 997 Å, 15 of which are in the infrared. The transitions at 12 899 Å and 12 975 Å are observed as strong features in the spectra of late-type stars and ultracool dwarfs. We have fitted our calculated spectra to the observed Mn I lines in spectra of late-type stars. Using the new experimentally measured Mn I log (gf) values together with existing data for Mn I hyperfine structure splitting factors we determined the manganese abundance to be log N(Mn) = −6.65 ± 0.05 in the atmosphere of the Sun, log N(Mn) = 6.95 ± 0.20 in the atmosphere of Arcturus, and log N(Mn) = −6.70 ± 0.20 in the atmosphere of M 9.5 dwarf 2MASSW 0140026+270150.

  • 11.
    Boualili, Fatima Zahra
    et al.
    USTHB, Lab Elect Quant, Fac Phys, BP 32, Algiers, Algeria..
    Nemouchi, Messaoud
    USTHB, Lab Elect Quant, Fac Phys, BP 32, Algiers, Algeria..
    Godefroid, Michel
    Univ Libre Bruxelles, Spect Quantum Chem & Atmospher Remote Sensing, CP 160-09, B-1050 Brussels, Belgium..
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Weak correlation and strong relativistic effects on the hyperfine interaction in fluorine2021In: Physical Review A: covering atomic, molecular, and optical physics and quantum information, ISSN 2469-9926, E-ISSN 2469-9934, Vol. 104, no 6, article id 062813Article in journal (Refereed)
    Abstract [en]

    In previous work devoted to ab initio calculations of hyperfine-structure constants in nitrogen and fluorine atoms, we observed sizable relativistic effects, a priori unexpected for such light systems, that can even largely dominate over electron correlation. We observed that the atomic wave functions calculated in the Breit-Pauli approximation describe adequately the relevant atomic levels and hyperfine structures, even in cases for which a small relativistic LS-term mixing becomes crucial. In the present work we identify levels belonging to the spectroscopic terms 2p(4)(P-3)3d(2,4)(P, D, F) of the fluorine atom, for which correlation effects on the hyperfine structures are small, but relativistic LS-term admixtures are decisive to correctly reproduce the experimental values. The Breit-Pauli analysis of the hyperfine matrix elements nails cases with large cancellation, either between LS pairs for individual hyperfine operators or between the orbital and the spin dipole contributions. Multiconfiguration Dirac-Hartree-Fock calculations are performed to support the Breit-Pauli analysis.

  • 12.
    Bäckström, E.
    et al.
    Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm, Sweden.
    Gurell, J.
    Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm, Sweden.
    Royen, P.
    Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm, Sweden.
    Mannervik, S.
    Department of Physics, AlbaNova University Center, Stockholm University, SE-106 91 Stockholm, Sweden.
    Norlin, L.
    Department of Nuclear Physics, AlbaNova University Center, Royal Institute of Technology, SE-106 91 Stockholm, Sweden.
    Blackwell-Whitehead, R.
    Lund Observatory, Lund University, SE-221 00 Lund, Box 43, Sweden.
    Hartman, H.
    Lund Observatory, Lund University, SE-221 00 Lund, Box 43, Sweden.
    Nilsson, H.
    Lund Observatory, Lund University, SE-221 00 Lund, Box 43, Sweden.
    The FERRUM project: metastable lifetimes in Cr ii2011In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 420, no 2, p. 1636-1639Article in journal (Refereed)
    Abstract [en]

    Parity forbidden radiative transitions from metastable levels are observed in spectra of low-density astrophysical plasmas. These lines are used as probes of the physical conditions, made possible due to the long lifetime of their upper level. In a joint effort, the FERRUM project aims to obtain new and accurate atomic data for the iron-group elements, and part of this project concerns forbidden lines. The radiative lifetimes of the metastable energy levels 3 d4(a 3 D)4 s   c4 D 5/2 and 3 d4(a 3 D)4 s   c4 D 7/2 of singly ionized chromium have been measured. The experiment has been performed at the ion storage ring CRYRING. We employed a laser-probing technique developed for measuring long lifetimes. In this article, we present the lifetimes of these levels to be τ5/2= 1.28(16) s and τ7/2= 1.37(7) s, respectively. A comparison with previous theoretical work shows good agreement and the result is discussed in a theoretical context.

  • 13. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Godefroid, Michel R
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Hyperfine structure of near-infrared transitions in neutral nitrogen revisited2009Conference paper (Other academic)
  • 14. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Hyperfine structure of low-lying states of 14;15N (Cairns)2010In: Book of abstracts: Monday posters 3, 2010, p. 238-238Conference paper (Other academic)
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  • 15. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Hyperfine structure of low-lying states of 14;15N (Salamanca)2010Conference paper (Other academic)
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  • 16. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Hyperfine structure of low-lying states of 14;15N (Vilnius)2010In: Book of Abstracts, 2010, p. 90-90, article id B-11Conference paper (Other academic)
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  • 17. Carette, Thomas
    et al.
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Godefroid, Michel
    Saturation spectra of low lying states of Nitrogen: reconciling experiment with theory2010In: European Physical Journal D: Atomic, Molecular and Optical Physics, ISSN 1434-6060, E-ISSN 1434-6079, Vol. 60, no 2, p. 231-242Article in journal (Refereed)
    Abstract [en]

    The hyperfine constants of the levels 2p2(3P)3s 4PJ, 2p2(3P)3p 4Po J and 2p2(3P)3p 4Do J, deduced by Jennerich et al. [Eur. Phys. J. D 40, 81 (2006)] from the observed hyperfine structures of the transitions 2p2(3P)3s 4PJ → 2p2(3P)3p 4Po J and 2p2(3P)3s 4PJ → 2p2(3P)3p 4Do J recorded by saturation spectroscopy in the near-infrared, strongly disagree with the ab initio values of Jönsson et al. [J. Phys. B: At. Mol. Opt. Phys. 43, 115006 (2010)]. We propose a new interpretation of the recorded weak spectral lines. If the latter are indeed reinterpreted as crossover signals, a new set of experimental hyperfine constants is deduced, in very good agreement with the ab initio predictions.

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  • 18.
    Ekman, Jörgen
    et al.
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Godefroid, Michel R.
    Univ Libre Bruxelles, Chim Quant & Photophys, B-1050 Brussels, Belgium..
    Hartman, Henrik
    Malmö högskola, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Validation and Implementation of Uncertainty Estimates of Calculated Transition Rates2014In: Atoms, E-ISSN 2218-2004, Vol. 2, no 2, p. 215-224Article, review/survey (Refereed)
    Abstract [en]

    Uncertainties of calculated transition rates in LS-allowed electric dipole transitions in boron-like O IV and carbon-like Fe XXI are estimated using an approach in which differences in line strengths calculated in length and velocity gauges are utilized. Estimated uncertainties are compared and validated against several high-quality theoretical data sets in O IV, and implemented in large scale calculations in Fe XXI.

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  • 19.
    Ekman, Jörgen
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Godefroid, M.
    Naze, C.
    Gaigalas, G.
    Bieron, J.
    RIS4: A program for relativistic isotope shift calculations2019In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 235, p. 433-446Article in journal (Refereed)
    Abstract [en]

    Spectral lines from different isotopes display a small separation in energy, commonly referred to as the line isotope shift. The program RIS4 (Relativistic Isotope Shift) calculates normal and specific mass shift parameters as well as field shift electronic factors from relativistic multiconfiguration Dirac-Hartree-Fock wave functions. These quantities, together with available nuclear data, determine isotope-dependent energy shifts. Using a reformulation of the field shift, it is possible to study, in a model-independent way, the atomic energy shifts arising from changes in nuclear charge distributions, e.g. deformations. (C) 2018 Published by Elsevier B.V.

  • 20.
    Eriksson, M.
    et al.
    University of Kalmar, 391 82 Kalmar, Sweden; Space Telescope Science Institute, 3700 San Martin drive, Baltimore, MD 21218, USA.
    Nilsson, Hampus
    Atomic Astrophysics, Lund Observatory, Box 43, 221 00 Lund, Sweden.
    Veenhuizen, H.
    University of Kalmar, 391 82 Kalmar.
    Long, K. S.
    Space Telescope Science Institute, 3700 San Martin drive, Baltimore, MD 21218, USA.
    Modeling of C IV pumped fluorescence of Fe II in symbiotic stars2007In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 477, no 1, p. 255-265Article in journal (Refereed)
  • 21.
    Fierro Tobar, Raul
    et al.
    Malmö University, Faculty of Technology and Society (TS).
    Yuku, Marius
    Malmö University, Faculty of Technology and Society (TS).
    Atomic wear mechanisms of hard chrome against Al2O32021Independent thesis Basic level (university diploma), 10 credits / 15 HE creditsStudent thesis
    Abstract [en]

    Hard chrome exhibit hardness of about 70 HRC and lubricity that prevents seizing and galling and is therefore the common first choice for engineers to reduce friction and minimize wear. These properties enable engineering applications such as cutting and drilling, especially in manufacturing, production and consumer good industries. Hard chrome has a wide set of functions as being decorative, corrosion resistant and ease cleaning procedures. Hence, electroplating is a common process to synthesize hard chrome butthis process is banned by EU due to the rise of hazardous components. However, the need for alternative material is at rise but, fundamental issues for hard chrome are yet to be solved.

    The purpose of the work is to develop atomic structures for two systems using different programs such as OpenMX, VESTA and Ovito. The goal is to identify atomic wear mechanisms of hard chrome in an ideal system (Al2O3- Cr) and a real system (Al2O3 - Cr2O3) using density functional theory (DFT). These two systems are analyzed since every surface oxidises in air (real system) and under increased mechanical loads the pristine surface of hard chrome (ideal system) can be exposed to the counter body (Al2O3). DFT based molecular dynamics simulations are carried out at a temperature of 300 K and a sliding speed of 10 ms−1. The simulation interval is 0-15000 fs and radial distribution function (RDF) is employed to analyse the atomic wear mechanisms. Both systems start to show adhesive wear due to amorphization, mixed with signs of abrasive wear on the atomic scale. The systems are further analyzed using electron density distribution (EDD), that plots electronic structures enhancing the analyse of different type of bondstaking place. The bulk structures mainly show covalent bonds with ionic and metallic bonds less represented. Furthermore, same observations have been made for the interfaces of the ideal and real system.

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  • 22.
    Fivet, V
    et al.
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Biémont, É
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium; IPNAS, Université de Liège, Sart Tilman, B-4000 Liège, Belgium.
    Engström, L
    Department of Physics, Lund Institute of Technology, PO Box 118, SE-221 00 Lund, Sweden.
    Lundberg, H
    Department of Physics, Lund Institute of Technology, PO Box 118, SE-221 00 Lund, Sweden.
    Nilsson, H
    Lund Observatory, Lund University, PO Box 43, SE-22100 Lund, Sweden.
    Palmeri, P
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Quinet, P
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium; IPNAS, Université de Liège, Sart Tilman, B-4000 Liège, Belgium.
    Radiative lifetime measurements and calculations in doubly ionized tantalum (Ta III)2007In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 41, no 1, p. 015702-015702Article in journal (Refereed)
    Abstract [en]

    Radiative lifetimes of six odd-parity levels belonging to the 5d26p configuration of doubly ionized tantalum (Ta III) have been measured using the time-resolved-laser-induced- fluorescence technique. Supporting theoretical calculations, including core-polarization effects, have been performed to model configuration interaction and to estimate branching fractions. The excellent agreement between the theoretical and experimental lifetimes allows us to assess the reliability of the 206 calculated transition probabilities. It is expected that this new set of results will be useful to astrophysicists for the investigation of the chemical composition of stars.

  • 23.
    Fivet, V.
    et al.
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Quinet, P.
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium; IPNAS, Université de Liège, B-4000 Liège, B15 Sart Tilman, Belgium.
    Palmeri, P.
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium.
    Biémont, É.
    Astrophysique et Spectroscopie, Université de Mons-Hainaut, B-7000 Mons, Belgium; IPNAS, Université de Liège, B-4000 Liège, B15 Sart Tilman, Belgium.
    Asplund, M.
    Max Planck Institute for Astrophysics, D-85741 Garching, Postfach 1317, Germany.
    Grevesse, N.
    Centre Spatial de Liège, B-4031 Angleur-Liège, Avenue Pré Aily, Belgium; Institut d'Astrophysique et de Géophysique, Université de Liège, B-4000 Liège, Allée du 6 Août,17, B5C, Belgium.
    Sauval, A. J.
    Observatoire Royal de Belgique, B-1180 Bruxelles, Avenue Circulaire, 3, Belgium.
    Engström, L.
    Department of Physics, Lund University, SE-221 00 Lund, PO Box 118, Sweden.
    Lundberg, H.
    Department of Physics, Lund University, SE-221 00 Lund, PO Box 118, Sweden.
    Hartman, H.
    Lund Observatory, Lund University, SE-221 00 Lund, PO Box 43, Sweden.
    Nilsson, H.
    Lund Observatory, Lund University, SE-221 00 Lund, PO Box 43, Sweden.
    Experimental and theoretical radiative decay rates for highly excited ruthenium atomic levels and the solar abundance of ruthenium2009In: Monthly notices of the Royal Astronomical Society, ISSN 0035-8711, E-ISSN 1365-2966, Vol. 396, no 4, p. 2124-2132Article in journal (Refereed)
    Abstract [en]

    The solar photospheric abundance of ruthenium is revised on the basis of a new set of oscillator strengths derived for Ru i transitions with wavelengths in the spectral range 2250-4710 Å. The new abundance value (in the usual logarithmic scale where the solar hydrogen abundance is equal to 12.00), A Ru = 1.72 ± 0.10, is in agreement with the most recent meteoritic result, ARu = 1.76 ± 0.03. The accuracy of the transition probabilities, obtained using a relativistic Hartree-Fock model including core-polarization effects, has been assessed by comparing the theoretical lifetimes with previous experimental results. A comparison is also made with new measurements performed in this work by the time-resolved laser-induced fluorescence spectroscopy for 10 highly excited odd-parity levels of Ru i.

  • 24. Froese Fischer, Charlotte
    et al.
    Godefroid, Michel
    Verdebout, Simon
    Gaigalas, Gediminas
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Configuration interaction with separately optimized pair correlation functions2010Conference paper (Other academic)
    Abstract [en]

    Variational methods produce one-electron radial functions that minimize the total energy of the system. Independent pair correlation functions (PCFs) designed to represent a specific correlation effect – valence, core-valence, or core-core – can be obtained from multiconfiguration Hartree-Fock (MCHF) or Dirac-Hartree-Fock (MCDHF) calculations [1,2]. These separately optimized and nonorthogonal PCFs may then be coupled by solving the associated generalized eigenproblem. In the present study, the Hamiltonian and overlap matrix elements are evaluated through biorthonormal orbital transformations and efficient counter-transformation of the configuration interaction eigenvectors [3]. The ground state of Be atom has been thoroughly tested by this method for various computational strategies and correlation models. It has been shown that the energy convergence is faster than with the usual SD-MCHF method of optimizing a single, orthonormal, one-electron orbital basis spanning the complete configuration space. Beryllium is a small system for which basis saturation can be achieved through complete active space MCHF expansions. But for larger systems describing electron correlation in all space by optimizing a common orthonormal set becomes hopeless whereas the calculation of additional PCFs is straight forward. Our independent optimization scheme, raises many questions related in the choice of the zero-order model to be used when building the interaction matrix. The present study is the first step in the current development of the extension of the atsp2K and grasp2K packages [1,2] that will adopt the biorthonormal treatment for energies, isotope shifts, hyperfine structures and transition probabilities.

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  • 25. Gaffney, K J
    et al.
    Lindenberg, A M
    Larsson, J
    Sokolowski-Tinten, K
    Blome, C
    Synnergren, O
    Sheppard, J
    Caleman, C
    MacPhee, A G
    Weinstein, D
    Lowney, D P
    Allison, T
    Matthews, T
    Falcone, R W
    Cavalieri, A L
    Fritz, D M
    Lee, S H
    Bucksbaum, P H
    Reis, D A
    Rudati, J
    Macrander, A T
    Fuoss, P H
    Kao, C C
    Siddons, D P
    Pahl, R
    Moffat, K
    Als-Nielsen, J
    Duesterer, S
    Ischebeck, R
    Schlarb, H
    Schulte-Schrepping, H
    Schneider, J
    von der Linde, D
    Hignette, O
    Sette, F
    Chapman, H N
    Lee, R W
    Hansen, T N
    Wark, J S
    Bergh, M
    Huldt, G
    van der Spoel, D
    Timneanu, N
    Hajdu, J
    Akre, R A
    Bong, E
    Krejcik, P
    Arthur, J
    Brennan, S
    Luening, K
    Hastings, J B
    Observation of structural anisotropy and the onset of liquidlike motion during the nonthermal melting of InSb2005In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 95, no 12, article id 125701Article in journal (Refereed)
    Abstract [en]

    The melting dynamics of laser excited InSb have been studied with femtosecond x-ray diffraction. These measurements observe the delayed onset of diffusive atomic motion, signaling the appearance of liquidlike dynamics. They also demonstrate that the root-mean-squared displacement in the [111] direction increases faster than in the [110] direction after the first 500 fs. This structural anisotropy indicates that the initially generated fluid differs significantly from the equilibrium liquid.

  • 26.
    Gaigalas, G.
    et al.
    Vilnius University, Lithuania.
    Rynkun, P.
    Vilnius University, Lithuania.
    Radziute, L.
    Vilnius University, Lithuania.
    Jönsson, Per
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Wang, K.
    Hebei University, China; Fudan University, China.
    Energy and transition data computations for P-like ions: As, Kr, Sr, Zr, Mo, and W2021In: Atomic Data and Nuclear Data Tables, ISSN 0092-640X, E-ISSN 1090-2090, Vol. 141, article id 101428Article in journal (Refereed)
    Abstract [en]

    The multiconfiguration Dirac-Hartree-Fock (MCDHF) and relativistic configuration interaction (RCI) methods were used to compute excitation energies and transition data for the 147 lowest states of the even 3s(3)p(4), 3s(2)3p2(3)d, 3p(4)3d, 3s(3)p(2)3d(2) configurations and for the 124 lowest states of the odd 3s23p3, 3p5, 3s3p33d, 3s(2)3p(3)d2, 3p(3)3d(2) configurations for the P-like ions: As XIX, Kr XXII, Sr XXIV, Zr XXVI, Mo XXVIII, and W LX. E1 transition rates and weighted oscillator strengths among these states are given. Valence-valence, core-valence and core-core electron correlation effects are included. Computed excitation energies and transition data are compared with the NIST recommended values and experimental or theoretical results of other authors. All calculations were performed using the general relativistic atomic structure package GRASP2018. (C) 2021 Elsevier Inc. All rights reserved.

  • 27. Gaigalas, Gediminas
    et al.
    Gaidamauskas, Erikas
    Bieron, Jacek
    Fritzsche, Stefan
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    MCDHF calculations of the electric dipole moment of radium induced by the nuclear Schiff moment2008Conference paper (Other (popular science, discussion, etc.))
  • 28. Gaigalas, Gediminas
    et al.
    Gaidamauskas, Erikas
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Multiconfiguration Dirac-Hartree-Fock calculations for the hyperfine-structure parameters and the scalar-pseudoscalar interaction constant of 133Cs2008In: Journal of Physics: Conference Series, Vol. 139, no 130, article id 012008Article in journal (Refereed)
    Abstract [en]

    In this work we investigate the applicability of the multiconfiguration Dirac-Hartree-Fock (MCDHF) method for calculating parity and time reversal symmetry violations in many-electron atoms. As an example we show results from calculations of the scalarpseudoscalar interaction constant for 133Cs. Calculated limits of this interaction constant are in a good agreement with other theories.

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  • 29. Godefroid, M
    et al.
    Nemouchi, M
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Theoretical study of the hyperfine structure and isotope shifts in near-infrared transitions of atomic nitrogen2008Conference paper (Other (popular science, discussion, etc.))
  • 30. Godefroid, Michel R
    et al.
    Carette, Thomas
    Nemouchi, Messaoud
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Ab initio study of the hyperfine structure and isotope shifts of near-infrared transitions in neutral nitrogen2009Conference paper (Other academic)
  • 31.
    Gurell, J.
    et al.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Hartman, H.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Blackwell-Whitehead, R.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Nilsson, H.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Bäckström, E.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Norlin, L. O.
    Department of Physics, Royal Institute of Technology, AlbaNova University Center, 10691 Stockholm, Sweden.
    Royen, P.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Mannervik, S.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    The FERRUM project: transition probabilities for forbidden lines in [Fe II] and experimental metastable lifetimes2009In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 508, no 1, p. 525-529Article in journal (Refereed)
    Abstract [en]

    Context. Accurate transition probabilities for forbidden lines are important diagnostic parameters for low-density astrophysical plasmas. In this paper we present experimental atomic data for forbidden [Fe II] transitions that are observed as strong features in astrophysical spectra. Aims. We measure lifetimes for the 3d6 (3G)4sa4 and 3d 6 (3D)4sb4 D1/2 metastable levels in Fe II and experimental transition probabilities for the forbidden transitions 3d7a4F7/2,9/2-3d6( 3G)4sa4.Methods. The lifetimes were measured at the ion storage ring facility CRYRING using a laser probing technique. Astrophysical branching fractions were obtained from spectra of Eta Carinae, obtained with the Space Telescope Imaging Spectrograph onboard the Hubble Space Telescope. The lifetimes and branching fractions were combined to yield absolute transition probabilities.Results. The lifetimes of the a4G11/2 and the b4D1/2 levels have been measured and have the following values, r = 0.75 ± 0.10 s respectively. Furthermore, we have determined the transition probabilities for two forbidden transitions of a 4F7/2,9/2-a4G11/2 at 4243.97 and 4346.85Å. Both the lifetimes and the transition probabilities are compared to calculated values in the literature. 

  • 32.
    Gurell, J.
    et al.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    Nilsson, H.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Engström, L.
    Atomic Physics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Lundberg, H.
    Atomic Physics, Department of Physics, Lund University, Box 118, 22100 Lund, Sweden.
    Blackwell-Whitehead, R.
    Lund Observatory, Lund University, Box 43, 22100 Lund, Sweden.
    Nielsen, K. E.
    Catholic University of America, Washington, DC 20064, USA; Astrophysics Science Division, Code 667, Goddard Space Flight Center, Greenbelt, MD 20771, USA.
    Mannervik, S.
    Department of Physics, Stockholm University, AlbaNova University Center, 10691 Stockholm, Sweden.
    The FERRUM project: laboratory-measured transition probabilities for Cr II2010In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 511, p. A68-A68Article in journal (Refereed)
    Abstract [en]

    Aims. We measure transition probabilities for Cr II transitions from the z 4HJ, z 2DJ, y 4FJ, and y 4GJ levels in the energy range 63 000 to 68 000 cm-1.Methods. Radiative lifetimes were measured using time-resolved laser-induced fluorescence from a laser-produced plasma. In addition, branching fractions were determined from intensity-calibrated spectra recorded with a UV Fourier transform spectrometer. The branching fractions and radiative lifetimes were combined to yield accurate transition probabilities and oscillator strengths.Results. We present laboratory measured transition probabilities for 145 Cr II lines and radiative lifetimes for 14 Cr II levels. The laboratory-measured transition probabilities are compared to the values from semi-empirical calculations and laboratory measurements in the literature.

  • 33. Harbst, M
    et al.
    Hansen, T N
    Caleman, C
    Fullagar, W K
    Jönsson, Per
    Malmö högskola, School of Technology (TS).
    Sondhauss, P
    Synnergren, O
    Malmö högskola, School of Technology (TS).
    Larsson, J
    Studies of resolidification of non-thermally molten InSb using time-resolved X-ray diffraction2005In: Applied Physics A: Materials Science & Processing, ISSN 0947-8396, E-ISSN 1432-0630, Vol. 81, no 5, p. 893-900Article in journal (Refereed)
    Abstract [en]

    We have used time-resolved X-ray diffraction to monitor the resolidification process of molten InSb. Melting was induced by an ultra-short laser pulse and the measurement conducted in a high-repetition-rate multishot experiment. The method gives direct information about the nature of the transient regrowth and permanently damaged layers. It does not rely on models based on surface reflectivity or second harmonic generation (SHG). The measured resolidification process has been modeled with a 1-D thermodynamic heat-conduction model. Important parameters like sample temperature, melting depth and amorphous surface layer thickness come directly out of the data, while mosaicity of the sample and free carrier density can be quantified by comparing with models. Melt depths up to 80 nm have been observed and regrowth velocities in the range 2-8 m/s have been measured.

  • 34.
    Hartman, Henrik
    et al.
    Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-221 00 Lund, Sweden.
    Nilsson, Hampus
    Department of Astronomy and Theoretical Physics, Lund University, Box 43, SE-221 00 Lund, Sweden.
    Engström, Lars
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Lundberg, Hans
    Department of Physics, Lund University, Box 118, SE-221 00 Lund, Sweden.
    Palmeri, Patrick
    Astrophysique et Spectroscopie, Université de Mons-UMONS, Place du Parc, 20, B-7000 Mons, Belgium.
    Quinet, Pascal
    Astrophysique et Spectroscopie, Université de Mons-UMONS, Place du Parc, 20, B-7000 Mons, Belgium; IPNAS, Université de Liège, B-4000 Liège, Belgium.
    Biémont, Émile
    Astrophysique et Spectroscopie, Université de Mons-UMONS, Place du Parc, 20, B-7000 Mons, Belgium; IPNAS, Université de Liège, B-4000 Liège, Belgium.
    Experimental and theoretical lifetimes and transition probabilities in Sb i2010In: Physical Review A. Atomic, Molecular, and Optical Physics, ISSN 1050-2947, E-ISSN 1094-1622, Vol. 82, no 5, article id 052512Article in journal (Refereed)
    Abstract [en]

    We present experimental atomic lifetimes for 12 levels in Sb i. The levels belong to the 5p2(3P)6s 2P, 4P, and 5p2(3P)5d 4P, 4F, and 2F terms. The lifetimes were measured using time-resolved laser-induced fluorescence. In addition, we report calculations of transition probabilities in Sb i using a multiconfigurational Dirac-Hartree-Fock method. The physical model was tested through comparisons between theoretical and experimental lifetimes for 5d and 6s levels. The lifetimes of the 5d 4F3/2,5/2,7/2 levels (19.5, 7.8, and 54 ns, respectively) depend strongly on the J value. This is explained by different degrees of level mixing for the different levels in the 4F term.

  • 35.
    Iantchenko, Alexei
    Malmö högskola, School of Technology (TS).
    Resonansfenomen i kvantmekaniken: Vad har resonanser för betydelse för vår världsbild2005Other (Other (popular science, discussion, etc.))
    Abstract [sv]

    Syfte med denna föreläsning är att introducera begreppet “resonans” och att övertyga er om att resonanser är en del av vår verklighet. Jag ska också ge exempel som visar hur resonanser kan användas för att studera vår värld. Föreläsning ska vara begriplig för alla. I föreläsningen introduceras begreppet “resonans” på grundläggande nivå. Exempel ges på hur renosanser kan användas för att studera vår värld. Renosanser är en del av vår verklighet - genom att mäta resonanser kan man skapa en bild av det verkliga objektet. Presentationen användes vid Alexei Iantchenkos docentföreläsning den 1 april 2005.

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  • 36.
    Ivarsson, S.
    et al.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Andersen, J.
    Astronomical Observatory, Niels Bohr Institute for Astronomy, Physics & Geophysics, Juliane Maries Vej 30, 2100 Copenhagen, Denmark; Nordic Optical Telescope Scientific Association, La Palma, Canary Islands, Spain.
    Nordström, B.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden; Astronomical Observatory, Niels Bohr Institute for Astronomy, Physics & Geophysics, Juliane Maries Vej 30, 2100 Copenhagen, Denmark.
    Dai, X.
    Atomic Physics, Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    Johansson, S.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Lundberg, H.
    Atomic Physics, Department of Physics, Lund Institute of Technology, PO Box 118, 22100 Lund, Sweden.
    Nilsson, H.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Hill, V.
    GEPI, Observatoire de Paris-Meudon (UMR 8111), DASGAL, 2 pl. Jules Janssen, 92195 Meudon Cedex, France.
    Lundqvist, M.
    Atomic Astrophysics, Lund Observatory, Lund University, PO Box 43, 22100 Lund, Sweden.
    Wyart, J. F.
    Laboratoire Aimé Cotton, Centre National de la Recherche Scientifique, Orsay, France.
    Improved oscillator strengths and wavelengths for Os I and Ir I, and new results on earlyr-process nucleosynthesis2003In: Astronomy and Astrophysics, ISSN 0004-6361, E-ISSN 1432-0746, Vol. 409, no 3, p. 1141-1149Article in journal (Refereed)
    Abstract [en]

    The radioactive decay of 238U and 232Th has recently been used to determine ages for some of the oldest stars in the Universe. This has highlighted the need for accurate observational constraints on production models for the heaviest r-process elements which might serve as stable references, notably osmium and iridium. In order to provide a firmer basis for the observed abundances, we have performed laser-induced fluorescence measurements and Fourier Transform Spectroscopy to determine new radiative lifetimes and branching fractions for selected levels in Os I and Ir I. From these data, we determine new absolute oscillator strengths and improved wavelengths for 18 Os I and 4 Ir I lines. A reanalysis of VLT spectra of CS 31082-001 and new results for other stars with Os and Ir detections show that (i): the lines in the UV and λ 4260 Å yield reliable Os abundances, while those at   4135, 4420 Å are heavily affected by blending; (ii): the Os and Ir abundances are identical in all the stars; (iii): the heavy-element abundances in very metal-poor stars conform closely to the scaled solar r-process pattern throughout the range 56 ≤ Z ≤ 77; and (iv): neither Os or Ir nor any lighter species are suitable as reference elements for the radioactive decay of Th and U.

     

  • 37.
    Johansson, S.
    et al.
    Atomic Astrophysics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden.
    Derkatch, A.
    Physics Department, Stockholm University, Stockholm, Sweden.
    Donnelly, M. P.
    Department of Applied Mathematics and Theoretical Physics, The Queens University of Belfast, Belfast, Northern Ireland.
    Hartman, Henrik
    Atomic Astrophysics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden.
    Hibbert, A.
    Department of Applied Mathematics and Theoretical Physics, The Queens University of Belfast, Belfast, Northern Ireland.
    Karlsson, H.
    Atomic Astrophysics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden.
    Kock, M.
    Institute for Atomic and Molecular Physics, University of Hannover, Hannover, Germany.
    Li, Z. S.
    Department of Physics, Lund Institute of Technology, Lund, Sweden.
    Leckrone, D. S.
    NASA / Goddard Space Flight Center, Greenbelt, Maryland, USA.
    Litzén, U.
    Atomic Astrophysics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden.
    Lundberg, H.
    Department of Physics, Lund Institute of Technology, Lund, Sweden.
    Mannervik, S.
    Physics Department, Stockholm University, Stockholm, Sweden.
    Norlin, L-O.
    Physics Department, Royal Institute of Technology, Stockholm, Sweden.
    Nilsson, H.
    Atomic Astrophysics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden.
    Pickering, J.
    Physics Department, Blackett Laboratory, Imperial College, London, UK.
    Raassen, T.
    Astronomical Institute "Anton Pannekoek", University of Amsterdam, Amsterdam, The Netherlands.
    Rostohar, D.
    Physics Department, Stockholm University, Stockholm, Sweden.
    Royen, P.
    Physics Department, Stockholm University, Stockholm, Sweden.
    Schmitt, A.
    Fachbereich Physik, University of Kaislerslautern, Kaiserslautern, Germany.
    Johanning, M.
    Institute for Atomic and Molecular Physics, University of Hannover, Hannover, Germany.
    Sikström, C. M.
    Atomic Astrophysics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden.
    Smith, P. L.
    Harvard-Smithsonian Center for Astrophysics, Cambridge MA, USA.
    Svanberg, S.
    Department of Physics, Lund Institute of Technology, Lund, Sweden.
    Wahlgren, G. M.
    Atomic Astrophysics, Lund Observatory, Box 43, SE-221 00 Lund, Sweden.
    The FERRUM Project: New f-value Data for Fe II and Astrophysical Applications2002In: Physica Scripta, ISSN 0031-8949, E-ISSN 1402-4896, Vol. T100, no 1, p. 71-71Article in journal (Refereed)
    Abstract [en]

    We present the FERRUM Project, an international collaboration aiming at a production and evaluation of oscillator strengths (transition probabilities) of selected spectral lines of singly ionized iron group elements, that are of astrophysical relevance. The results obtained include measurements and calculations of permitted and forbidden lines of Fe II. The data have been applied to both emission and absorption lines in astrophysical spectra. We make comparisons between experimental, theoretical and astrophysical f-values. We give a general review of the various measurements, and discuss the UV8 multiplet of Fe II around 1610 Å in detail.

  • 38.
    Jönsson, Per
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Theoretical studies of hyperfine effects2007In: Journal of Physics, Conference Series, ISSN 1742-6588, E-ISSN 1742-6596, Vol. 72, no Conference Series 72, article id 012011Article in journal (Refereed)
    Abstract [en]

    The development of space-based observatories has highlighted the need for atomic data. In this review we examine multiconfiguration methods for calculating these data. Particular emphasize is placed on hyperfine structure splittings and hyperfine induced transitions.

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  • 39.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Andersson, Martin
    HFSZEEMAN—A program for computing weak and intermediate field fine and hyperfine structure Zeeman splittings from MCDHF wave functions2008In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 178, p. 156-170Article in journal (Refereed)
    Abstract [en]

    Given electronic wave functions generated by the grasp2K relativistic atomic structure package, this program calculates diagonal magnetic dipole AJ and electric quadrupole BJ hyperfine interaction constants and Landé gJ factors. In addition the program computes diagonal and off-diagonal reduced hyperfine and Zeeman matrix elements and constructs the total interaction matrix for an atom in an external magnetic field. By diagonalizing the interaction matrix and plotting eigenvalues as functions of the magnetic field, Zeeman splittings of hyperfine levels are obtained. The method is applicable in the weak and intermediate field regions and yields results that are useful when analyzing spectra from e.g. EBIT sources and magnetic stars. The program can also be used in the field free limit to calculate mixing coefficients that determine rates of hyperfine induced transitions. For atoms with zero nuclear spin I the program computes splittings of the fine-structure levels.

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  • 40.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Andersson, Martin
    Spectral properties of In II from MCDHF calculations2007In: Journal of Physics B: Atomic, Molecular and Optical Physics, Vol. 40, p. 2417-2433Article in journal (Refereed)
    Abstract [en]

    We report extensive relativistic multiconfiguration Dirac–Hartree–Fock calculations of oscillator strengths and hyperfine structures for a large number of electric dipole transitions in In II. Results for the 5s21S0–5s5p3Po0 hyperfine induced transition are also presented. Core polarization is accounted for by means of explicit CI. To describe spin–polarization effects configuration state functions obtained by single excitations from all core-shells are included in the expansions. The computed oscillator strength for the 5s21S0–5s5p3Po1 intercombination transition is in good agreement with laser spectroscopy measurements of In+ ions in a radio-frequency trap. The calculated magnetic dipole hyperfine interaction constants agree very well with experimental constants derived from Fourier transform spectra. The problem with off-diagonal interactions affecting the hyperfine structures in closely spaced fine-structure levels is discussed.

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  • 41.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Andersson, Martin
    Brage, Tomas
    Calculations of Zeeman Splittings, Hyperfine Structures, Isotope Shifts, and Oscillator Strengths using the Grasp2K Relativistic Atomic Structure2007Conference paper (Other academic)
    Abstract [en]

    Progress in atomic structure calculations together with todays fast computers make it possible to accurately compute many spectroscopic properties in atoms and ions. Among these properties are oscillator strengths, but also hyperfine structures and isotopes shifts that broadens and shifts lines in high resolution stellar spectra. Lande g_J factors as well as splittings in intermediate and strong magnetic fields can be calculated with high accuracy. In this work we present some calculations that reflects the status of the computational methods.

  • 42.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Bieron, Jacek
    Relativistic configuration interaction calculations of energy levels, isotope shifts, hyperfine structures, and transition rates in the 2s22p2–2s2p3 transition array for the carbon-like sequence2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 7Article in journal (Refereed)
    Abstract [en]

    Energy levels, fine-structure separations, specific mass shift parameters, isotope shifts, hyperfine interaction constants, Landé gJ -factors and transition probabilities are reported for the 2s22p2–2s2p3 transition array in N II, O III, F IV, Ne V and Ti XVII. Wavefunctions were determined using the multiconfiguration Dirac–Hartree–Fock method with account for valence, core-valence and core–core correlation effects. The transition energies and rates are compared with experimental data and with values from other calculations.

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  • 43.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Bieron, Jacek
    Indelicato, Paul
    Multiconfiguration Dirac-Hartee-Fock calculations of transition rates and lifetime of the eight lowest excited levels of radium2007In: The European Physical Journal Special Topics, ISSN 1951-6355, E-ISSN 1951-6401, Vol. 144, p. 75-84Article in journal (Refereed)
    Abstract [en]

    The multiconfiguration Dirac-Hartree-Fock (MCDHF) model has been employed to calculate the transition rates between the nine lowest levels of radium. The dominant rates were then used to evaluate the radiative lifetimes. The decay of the metastable 7s7p 3P0 state through 2-photon E1M1 and hyperfine induced channels is also studied.

  • 44.
    Jönsson, Per
    et al.
    Malmö högskola, School of Technology (TS).
    Carette, Thomas
    Nemouchi, Messaoud
    Godefroid, Michel
    Ab initio calculations of 14N and 15N hyperfine structures2010In: Journal of Physics B: Atomic, Molecular and Optical Physics, ISSN 0953-4075, E-ISSN 1361-6455, Vol. 43, no 11, article id 115006Article in journal (Refereed)
    Abstract [en]

    Hyperfine structure parameters are calculated for the 2p2(3P)3s 4PJ, 2p2(3P)3p 4Po J and 2p2(3P)3p 4Do J levels, using the ab initio multiconfiguration Hartree–Fock method. The theoretical hyperfine coupling constants are in complete disagreement with the experimental values of Jennerich et al deduced from the analysis of the near-infrared Doppler-free saturated absorption spectra.

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  • 45.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Froese Fischer, Charlotte
    The GRASP2K Relativistic Atomic Structure Package.2008Conference paper (Other (popular science, discussion, etc.))
  • 46.
    Jönsson, Per
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Gaigalas, Gediminas
    Vilnius Univ, Inst Theoret Phys & Astron, LT-01022 Vilnius, Lithuania..
    Fischer, Charlotte Froese
    Univ British Columbia, Dept Comp Sci, Vancouver, BC V6T 1Z4, Canada..
    Bieron, Jacek
    Uniwersytet Jagiellonski, Inst Fizyki Teoretycznej, PL-30348 Krakow, Poland..
    Grant, Ian P.
    Univ Oxford, Math Inst, Andrew Wiles Bldg,Woodstock Rd, Oxford OX2 6GG, England..
    Brage, Tomas
    Lund Univ, Dept Phys, Div Math Phys, Box 118, SE-22100 Lund, Sweden..
    Ekman, Jörgen
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Godefroid, Michel
    Univ Libre Bruxelles, Spect Quantum Chem & Atmospher Remote Sensing, B-1050 Brussels, Belgium..
    Grumer, Jon
    Uppsala Univ, Dept Phys & Astron, Theoret Astrophys, Box 516, SE-75120 Uppsala, Sweden..
    Li, Jiguang
    6 Huayuan Rd, Beijing 100088, Peoples R China..
    Li, Wenxian
    Chinese Acad Sci, Key Lab Solar Act, Natl Astron Observ, Beijing 100012, Peoples R China..
    GRASP Manual for Users2023In: Atoms, E-ISSN 2218-2004, Vol. 11, no 4, article id 68Article in journal (Refereed)
    Abstract [en]

    grasp is a software package in Fortran 95, adapted to run in parallel under MPI, for research in atomic physics. The basic premise is that, given a wave function, any observed atomic property can be computed. Thus, the first step is always to determine a wave function. Different properties challenge the accuracy of the wave function in different ways. This software is distributed under the MIT Licence.

    Download full text (pdf)
    fulltext
  • 47.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Godefroid, M
    Nemouchi, M
    Theoretical Study of the Hyperfine Structure and Isotope Shifts in Near-Infrared Transitions of Atomic Nitrogen2008Conference paper (Other (popular science, discussion, etc.))
  • 48.
    Jönsson, Per
    et al.
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Godefroid, Michel
    Univ libre Bruxelles, Spect Quantum Chem & Atmospher Remote Sensing, B-1050 Brussels, Belgium..
    Gaigalas, Gediminas
    Vilnius Univ, Inst Theoret Phys & Astron, Vilnius, Lithuania..
    Ekman, Jörgen
    Malmö University, Faculty of Technology and Society (TS), Department of Materials Science and Applied Mathematics (MTM).
    Grumer, Jon
    Uppsala Univ, Dept Phys & Astron, Theoret Astrophys, Box 516, SE-75120 Uppsala, Sweden..
    Li, Wenxian
    Chinese Acad Sci, Key Lab Solar Act, Natl Astron Observ, Beijing 100101, Peoples R China..
    Li, Jiguang
    6 Huayuan Rd, Beijing 100088, Peoples R China..
    Brage, Tomas
    Lund Univ, Dept Phys, Div Math Phys, Box 118, SE-22100 Lund, Sweden..
    Grant, Ian P.
    Univ Oxford, Math Inst, Oxford OX2 6GG, England..
    Bieron, Jacek
    Uniwersytet Jagiellonski, Inst Fizyki Teoretycznej, PL-30348 Krakow, Poland..
    Fischer, Charlotte Froese
    Univ British Columbia, Dept Comp Sci, Vancouver, BC V6T 1Z4, Canada..
    An Introduction to Relativistic Theory as Implemented in GRASP2023In: Atoms, E-ISSN 2218-2004, Vol. 11, no 1, article id 7Article in journal (Refereed)
    Abstract [en]

    Computational atomic physics continues to play a crucial role in both increasing the understanding of fundamental physics (e.g., quantum electrodynamics and correlation) and producing atomic data for interpreting observations from large-scale research facilities ranging from fusion reactors to high-power laser systems, space-based telescopes and isotope separators. A number of different computational methods, each with their own strengths and weaknesses, is available to meet these tasks. Here, we review the relativistic multiconfiguration method as it applies to the General Relativistic Atomic Structure Package [grasp2018, C. Froese Fischer, G. Gaigalas, P. Jonsson, J. Bieron, Comput. Phys. Commun. (2018). DOI: 10.1016/j.cpc.2018.10.032]. To illustrate the capacity of the package, examples of calculations of relevance for nuclear physics and astrophysics are presented.

    Download full text (pdf)
    fulltext
  • 49.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    He, X
    Froese-Fischer, Charlotte
    Grant, I P
    The grasp2K relativistic atomic structure package2007In: Computer Physics Communications, ISSN 0010-4655, E-ISSN 1879-2944, Vol. 177, p. 597-622Article in journal (Refereed)
    Abstract [en]

    This paper describes grasp2K, a general-purpose relativistic atomic structure package. It is a modification and extension of the GRASP92 package by [F.A. Parpia, C. Froese Fischer, I.P. Grant, Comput. Phys. Comm. 94 (1996) 249]. For the sake of continuity, two versions are included. Version 1 retains the GRASP92 formats for wave functions and expansion coefficients, but no longer requires preprocessing and more default options have been introduced. Modifications have eliminated some errors, improved the stability, and simplified interactive use. The transition code has been extended to cases where the initial and final states have different orbital sets. Several utility programs have been added. Whereas Version 1 constructs a single interaction matrix for all the J's and parities, Version 2 treats each J and parity as a separate matrix. This block structure results in a reduction of memory use and considerably shorter eigenvectors. Additional tools have been developed for this format. The CPU intensive parts of Version 2 have been parallelized using MPI. The package includes a “make” facility that relies on environment variables. These make it easier to port the application to different platforms. The present version supports the 32-bit Linux and ibmSP environments where the former is compatible with many Unix systems. Descriptions of the features and the program/data flow of the package will be given in some detail in this report.

  • 50.
    Jönsson, Per
    et al.
    Malmö högskola, School of Teacher Education (LUT), Nature-Environment-Society (NMS).
    Li, J
    Gaigalas, Gediminas
    Dong, Z
    Hyperfine Structures, Isotope Shifts and Transition Rates of C II, N III, and O IV from Relativistic Configuration Interaction Calculations2008Conference paper (Other (popular science, discussion, etc.))
123 1 - 50 of 134
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