Density-sensitive electric quadrupole decays in Ni-like ions observed in laser-produced plasmas

Wyart, J.-F.; Bauche‐Arnoult, C.; Gauthier, J. C.; Geindre, J. P.; Monier, P.; Klapisch, M.; Bar‐Shalom, A.; Cohn, Arthur

doi:10.1103/physreva.34.701

Cited by 32 publications

(7 citation statements)

References 13 publications

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“…1). There are extensive theoretical [1,2] and experimental [3][4][5][6][7][8] investigations of nickel-like ions. However, very few studies, either theoretical or experimental, have dealt with the more ''exotic'' M3 decay.…”

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confidence: 99%

MF-Dependent Lifetimes due to Hyperfine Induced Interference Effects

et al. 2006

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We report on the first theoretical investigation of M F -dependent lifetimes due to interference between a magnetic octupole transition and a hyperfine induced electric quadrupole transition. Extensive multiconfiguration Dirac-Fock calculations are used to model the hyperfine quenching of the magnetic octupole decay of 3d 9 4s were reported also in [11]. The measured lifetimes in the latter two cases, 8:2 2:0 ms and 4:3 3:6 ms, respectively, have larger error bars. These measurements are more than 60% shorter than what has so far been predicted by theory [12,13]. We suggest that these discrepancies are due to the hyperfine induced state mixing between the 3 D 3 and 3 D 2 levels, opening a new decay process. We also propose for the first time that the interference between the M3 transition and the hyperfine induced E2 transition results in lifetimes which are dependent on the magnetic quantum number of the initial level. Our arguments are supported by large-scale MCDF calculations and by simulations of the resulting complex 3 D 3 decay by oneexponential fitting. The basic ideas behind hyperfine quenching is that in the presence of a nuclear spin I, an additional hyperfine operator H hpf is introduced into the otherwise electronic Hamiltonian. This Hamiltonian commutes with the total angular moment F J I and F z , instead of the total electronic angular moment J and J z . This hyperfine interaction therefore not only splits J levels, but also introduces a wave function mixing between levels of different J [14]. An experimental indication of hyperfine quenching was reported by Gould et al. [15]. The mixing can be represented as j"ÿJIF"i jÿwhere ÿ denotes all other quantum numbers needed to completely specify the state, and the main contribution represents the ''pure'' state jÿ 0 J 0 IFi, in the absence of the hyperfine interaction. According to first order perturbation theory, the mixing coefficient can be computed asFIG. 1. Schemes of the ground level 3d 10 1 S 0 and first excited levels 3d 9 4s 1;3 D in Ni-like ions. The main decays involved are also given. LS term designation is used.

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MF-Dependent Lifetimes due to Hyperfine Induced Interference Effects

et al. 2006

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“…However, they can be important in some circumstances [14,15,16]. For instance, electric-quadrupole decays were observed in the spectra of neon-like [17] and nickel-like [18] ions produced by laser irradiation. As mentioned before, forbidden lines can arise from metastable levels of excited configurations [19].…”

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confidence: 99%

Statistics of electric-quadrupole lines in atomic spectra

Pain¹,

Gilleron²,

Bauche³

et al. 2012

J. Phys. B: At. Mol. Opt. Phys.

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In hot plasmas, a temperature of a few tens of eV is sufficient for producing highly stripped ions where multipole transitions become important. At low density, the transitions from tightly bound inner shells lead to electric-quadrupole lines which are comparable in strength with electric-dipole ones. In the present work, we propose analytical formulas for the estimation of the number of E2 lines in a transition array. Such expressions rely on statistical descriptions of electron states and J-levels. A generalized "J-file" sum rule for E2 lines and the strength-weighted shift and variance of the line energies of a transition array nℓ N+1 → nℓ N n ′ ℓ ′ of inter-configuration E2 lines are also presented.

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“…Electric and magnetic quadrupole (E2 and M 2, respectively) transitions are also often observed in laboratory and astrophysical plasmas. A typical example of E2 transition is [3d 10 ] J=0 -[3d 9 4s] J=2 in Ni-like ions [11,12] whereas that of M 2 transition is 1 1 S 0 -2 3 P 2 (the line often indicated as "x") in He-like ions [13,14].…”

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Observation of electric octupole emission lines strongly enhanced by the anomalous behavior of a cascading contribution

et al. 2019

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We present extreme ultraviolet spectra of Ag-like W 27+ observed with an electron beam ion trap. In the spectra, the 4f 7/2,5/2 -5s transitions are identified as the first observation of spontaneous electric octupole emission. Our theoretical investigation shows that the emission line intensity is strongly and specifically enhanced at the atomic number 74 by an anomalous behavior of cascading contribution to 5s via 5p ← 5d.

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Density-sensitive electric quadrupole decays in Ni-like ions observed in laser-produced plasmas

Cited by 32 publications

References 13 publications

MF-Dependent Lifetimes due to Hyperfine Induced Interference Effects

MF-Dependent Lifetimes due to Hyperfine Induced Interference Effects

Statistics of electric-quadrupole lines in atomic spectra

Observation of electric octupole emission lines strongly enhanced by the anomalous behavior of a cascading contribution

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