Identification of<i>n</i>= 4, Δ<i>n</i>= 0 Transitions in the Spectra of Nickel-like Cadmium Ions from a Capillary Discharge Plasma Column

Rahman, Abdur; Hammarsten, E. C.; Sakadic, S.; Rocca, J. J.; Wyart, J.-F.

doi:10.1238/physica.regular.067a00414

Cited by 21 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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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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“…effects included. Notes: a Wavelength from ref [11]. The present spectra lead to an unresolved peak with global intensity 7 S line is too strong with regard to the gA value S, Ag XXI This Ag XX transition is probably masked by a AgXXI transition.…”

Section: Interpretation Of the Silver Spectramentioning

confidence: 86%

“…The same theoretical methods previously used to classify lines from CdXXI [11] was used for AgXX. The advantages of the Generalized least-squares (GLS) techniques for improving the reliability of multicharged ions predicted energies in the framework of the Racah-Slater method had been stressed in Ref.…”

Section: Interpretation Of the Silver Spectramentioning

confidence: 99%

“…The further development of practical lasers operating in this wavelength region generates significant interest in the spectra of these Nilike ions. Recently, a detailed spectroscopic study of Nilike Cd has been reported utilizing a capillary discharge plasma [11]. Numerous newly identified Ni-like cadmium transitions were observed and classified in the 12.7-18.4 nm wavelength region in a cadmium plasma excited by such a discharge.…”

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confidence: 99%

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Classification of the Nickel-Like Silver Spectrum (Ag XX) from a Fast Capillary Discharge Plasma

2004

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A study of the Ni-like silver (AgXX) spectra in the 13:7-20:5 nm wavelength region using a plasma generated by a fast high power capillary discharge is reported. Forty-three AgXX transitions have been identified with the assistance of calculations performed using the Slater-Condon method with generalized least-squares fits of the energy parameters. The average difference between the measured transition wavelengths and the theoretical values is 0.0026 nm.

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“…This intrinsic limitation of the kinetic conversion scheme makes it difficult to extend it to applications such as the development of sub-10 nm wavelength lasers, which require axially uniform plasma columns that are significantly denser and hotter (e.g. 26 times ionized Xe [14,15] and electron temperatures of ~400 eV). Such scaling is particularly challenging for high-Z plasmas where radiative cooling is large [5].…”

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confidence: 99%