| 1. |
- Barzakh, A., et al.
(författare)
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Large Shape Staggering in Neutron-Deficient Bi Isotopes
- 2021
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Ingår i: Physical Review Letters. - 0031-9007. ; 127:19
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Tidskriftsartikel (refereegranskat)abstract
- The changes in the mean-square charge radius (relative to Bi209), magnetic dipole, and electric quadrupole moments of Bi187,188,189,191 were measured using the in-source resonance-ionization spectroscopy technique at ISOLDE (CERN). A large staggering in radii was found in Bi187,188,189g, manifested by a sharp radius increase for the ground state of Bi188 relative to the neighboring Bi187,189g. A large isomer shift was also observed for Bi188m. Both effects happen at the same neutron number, N=105, where the shape staggering and a similar isomer shift were observed in the mercury isotopes. Experimental results are reproduced by mean-field calculations where the ground or isomeric states were identified by the blocked quasiparticle configuration compatible with the observed spin, parity, and magnetic moment. © 2021 authors.
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| 2. |
- Mukai, M., et al.
(författare)
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In-gas-cell laser resonance ionization spectroscopy of Ir-196,Ir-197,Ir-198
- 2020
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Ingår i: Physical Review C. - : American Physical Society. - 2469-9985 .- 2469-9993. ; 102:5
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Tidskriftsartikel (refereegranskat)abstract
- Hyperfine structure (HFS) measurements of neutron-rich iridium isotopes Ir-196,Ir-197,Ir-198 (Z = 77, N = 119-121) were performed via in-gas-cell laser resonance ionization spectroscopy at the KEK Isotope Separation System. Magnetic dipole moments mu and isotope shifts were determined from the HFS spectra. The variation of mean-square charge radii and quadrupole deformation parameters of these isotopes were evaluated from the isotope shifts. The mu value of (197)h, agreed with a theoretical value based on the strong coupling model, and the Ir nucleus was interpreted as prolately deformed by the theoretical calculations. The mu values of Ir-196,Ir-198 were also compared with semiempirical values calculated based on the strong coupling model. From the comparison, we can suggest the possible spin values of I-pi = 1,2(-) for Ir-196 and I-pi = 1(-) for Ir-198.
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| 3. |
- Wraith, Calvin, et al.
(författare)
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Evolution of nuclear structure in neutron-rich odd-Zn isotopes and isomers
- 2017
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 771, s. 385-391
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Tidskriftsartikel (refereegranskat)abstract
- Collinear laser spectroscopy was performed on Zn (Z = 30) isotopes at ISOLDE, CERN. The study of hyperfine spectra of nuclei across the Zn isotopic chain, N = 33–49, allowed the measurement of nuclear spins for the ground and isomeric states in odd-A neutron-rich nuclei up to N = 50. Exactly one longlived (>10 ms) isomeric state has been established in each 69–79Zn isotope. The nuclear magnetic dipole moments and spectroscopic quadrupole moments are well reproduced by large-scale shell–model calculations in the f5pg9 and fpg9d5 model spaces, thus establishing the dominant term in their wave function. The magnetic moment of the intruder Iπ = 1/2+ isomer in 79Zn is reproduced only if the νs1/2 orbital is added to the valence space, as realized in the recently developed PFSDG-U interaction.The spin and moments of the low-lying isomeric state in 73Zn suggest a strong onset of deformation at N = 43, while the progression towards 79Zn points to the stability of the Z = 28 and N = 50 shell gaps, supporting the magicity of 78Ni
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| 4. |
- Xie, L., et al.
(författare)
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Nuclear charge radii of Zn62-80 and their dependence on cross-shell proton excitations
- 2019
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Ingår i: Physics Letters B. - : Elsevier. - 0370-2693 .- 1873-2445. ; 797
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Tidskriftsartikel (refereegranskat)abstract
- Nuclear charge radii of Zn62-80 have been determined using collinear laser spectroscopy of bunched ion beams at CERN-ISOLDE. The subtle variations of observed charge radii, both within one isotope and along the full range of neutron numbers, are found to be well described in terms of the proton excitations across the Z = 28 shell gap, as predicted by large-scale shell model calculations. It comprehensively explains the changes in isomer-to-ground state mean square charge radii of Zn69-79, the inversion of the odd-even staggering around N = 40 and the odd-even staggering systematics of the Zn charge radii. With two protons above Z = 28, the observed charge radii of the Zn isotopic chain show a cumulative effect of different aspects of nuclear structure including single particle structure, shell closure, correlations and deformations near the proposed doubly magic nuclei, Ni-68 and Ni-78. (C) 2019 The Author(s). Published by Elsevier B.V.
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| 5. |
- Godefroid, M., et al.
(författare)
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More than local adaptation: high diversity of response to seawater acidification in seven coral species from the same assemblage in French Polynesia
- 2021
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Ingår i: Journal of the Marine Biological Association of the United Kingdom. - : Cambridge University Press (CUP). - 0025-3154 .- 1469-7769. ; 101:4, s. 675-683
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Tidskriftsartikel (refereegranskat)abstract
- Responses of corals to seawater acidification have been extensively studied. Sensitivity varies widely between species, highlighting the need to avoid extrapolation from one to another to get an accurate understanding of coral community responses. We tested the responses of seven coral species (Acropora cytherea, Acropora hyacinthus, Acropora pulchra, Leptastrea pruinosa, Montipora grisea, Pavona cactus, Pocillopora verrucosa) from the Mo'orea lagoon to a 48-day exposure to three pH scenarios (pH 7.95, 7.7 and 7.3). Tissue necrosis, mortality, growth rates, photophysiological performances and colour index were recorded. Few significant differences were noted between pH 7.95 and 7.7, but species-specific responses were observed at pH 7.3. While our data do not allow identification of the mechanisms behind this diversity in response between species inhabiting the same environment, it can exclude several hypotheses such as local adaptation, skeletal type, corallum morphology or calcification rate as sole factors determining coral sensitivity to pH.
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| 6. |
- Godefroid, M., et al.
(författare)
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Two decades of seawater acidification experiments on tropical scleractinian corals: Overview, meta-analysis and perspectives
- 2022
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Ingår i: Marine Pollution Bulletin. - : Elsevier BV. - 0025-326X. ; 178
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Tidskriftsartikel (refereegranskat)abstract
- Ocean acidification has emerged as a major concern in the last fifteen years and studies on the impacts of seawater acidification on marine organisms have multiplied accordingly. This review aimed at synthesizing the literature on the effects of seawater acidification on tropical scleractinians under laboratory-controlled conditions. We identified 141 articles (published between 1999 and 2021) and separated endpoints into 22 biological categories to identify global trends for mitigation and gaps in knowledge and research priorities for future investigators. The relative number of affected endpoints increased with pH intensity (particularly for endpoints associated to calcification and reproduction). When exposed to pH 7.6-7.8 (compared to higher pH), 49% of endpoints were affected. The diversity in experimental designs prevented deciphering the modulating role of coral life stages, genera or duration of exposure. Finally, important bias in research efforts included most experiments on adult corals (68.5%), in 27 out of 150 (18%) coral ecoregions and exclusively from shallow-waters.
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| 7. |
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| 8. |
- Nemouchi, M, et al.
(författare)
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Theoretical evaluation of the Be-7,9(-) 2s2p(2) P-4(1/2,3/2,5/2) hyperfine structure parameters and Be 2s2p P-3(o) electron affinity
- 2003
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Ingår i: Journal of Physics B: Atomic, Molecular and Optical Physics. - : IOP Publishing. - 0953-4075 .- 1361-6455. ; 36:11, s. 2189-2201
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Tidskriftsartikel (refereegranskat)abstract
- The hyperfine structures of Be-7,9(-) 2s2p(2) P-4(1/2,3/2,5/2) are investigated theoretically using the multiconfiguration Hartree-Fock and configuration interaction methods. The effects of the hyperfine mixing between the fine-structure J-levels are discussed. The feasibility of some atomic spectroscopy experiments, allowing determination of the Be-7 quadrupole moment from the observed hyperfine structure of the Be-7(-) negative ion and from the present electronic parameters, is investigated. The Be 2s2p P-3(o) electron affinity is monitored as a function of the orbital and configuration spaces to assess the reliability of the wavefunctions of the neutral atom and the negative ion. The theoretical value nicely converges towards the most recent theoretical and experimental results.
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| 9. |
- Song, C X, et al.
(författare)
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Isotope shifts in electron affinities and in binding energies of Pb and hyperfine structure of 207Pb
- 2024
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Ingår i: Journal of Chemical Physics. - : American Institute of Physics (AIP). - 0021-9606 .- 1089-7690. ; 160:21
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Tidskriftsartikel (refereegranskat)abstract
- The isotope shifts in electron affinities of Pb were measured by Walter et al. [Phys. Rev. A 106, L010801 (2022)] to be -0.002(4) meV for 207-208Pb and -0.003(4) meV for 206-208Pb by scanning the threshold of the photodetachment channel Pb-(S3/2◦4) - Pb (3P0), while Chen and Ning reported 0.015(25) and -0.050(22) meV for the isotope shifts on the binding energies measured relative to 3P2 using the SEVI method [J. Chem. Phys. 145, 084303 (2016)]. Here we revisited these isotope shifts by using our second-generation SEVI spectrometer and obtained -0.001(15) meV for 207-208Pb and -0.001(14) meV for 206-208Pb, respectively. In order to aid the experiment by theory, we performed the first ab initio theoretical calculations of isotope shifts in electron affinities and binding energies of Pb, as well as the hyperfine structure of 207Pb-, by using the MCDHF and RCI methods. The isotope shifts in electron affinities of 207-208Pb and 206-208Pb are -0.0023(8) and -0.0037(13) meV for the 3P0 channel, respectively, in good agreement with Walter et al.'s measurements. The isotope shifts in binding energies relative to 3P1,2, -0.0015(8) and -0.0026(13) meV for 207-208Pb and 206-208Pb, respectively, are compatible with the present measurements. The hyperfine constant for the ground state of 207Pb- obtained by the present calculations, A(S3/2◦4)=-1118 MHz, differs by a factor of 3 from the previous estimation by Bresteau et al. [J. Phys. B: At., Mol. Opt. Phys. 52, 065001 (2019)]. The reliability is supported by the good agreement between the theoretical and experimental hyperfine parameters of 209Bi.
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| 10. |
- Zhang, C. Y., et al.
(författare)
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Benchmarking calculations with spectroscopic accuracy of level energies and wavelengths in W LVII–W LXII tungsten ions
- 2021
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Ingår i: Journal of Quantitative Spectroscopy and Radiative Transfer. - : Elsevier. - 0022-4073 .- 1879-1352. ; 269
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Tidskriftsartikel (refereegranskat)abstract
- Atomic properties of n=3 states of the W56+ - W61+ ions are systematically investigated through two state-of-the-art methods, namely, the second-order many-body perturbation theory, and the multi-configuration Dirac–Hartree–Fock method combined with the relativistic configuration interaction approach. The contributions of valence-valence and core-valence electron correlations, the Breit interaction, the higher-order retardation correction beyond the Breit interaction through the transverse photon interaction, and the quantum electrodynamical corrections to the excitation energies are studied in detail. The excitation energies and wavelengths obtained with the two methods agree with each other within ≈0.01%. The present results achieve spectroscopic accuracy and provide a benchmark test for various applications and other theoretical calculations of W56+ - W61+ ions. They will assist spectroscopists in their assignment and direct identification of observed lines in complex spectra.
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