Relativistically prolonged lifetime of the 2s2p³P₀level of zero nuclear-spin beryllium-like ions

Abstract

The E1M1 transition rate of the s p P s S 2 2 2 3 0 2 1 0  line in beryllium-like ions has been calculated within the framework of relativistic second-order perturbation theory. Both multiconfiguration and quantum-electrodynamical computations have been carried out independently to better understand and test for all major electron-electron correlation contributions in the representation of the initial, intermediate and final states. By comparing the results from these methods, which agree well for all ions along the beryllium isoelectronic sequence, the lifetime of the metastable 2s2p 3 P 0 level is found to be longer by about 2-3 orders of magnitude for all medium and heavy elements than was estimated previously. This makes the 3 P 0 level of beryllium-like ions to one of the longest living (low-lying) electronic excitations of a tightly bound system with potential applications for atomic clocks and in astro physics and plasma physics.

Physics book: CRYRING@ESR

“…Radiative transition rates in atomic systems are among the fundamental entities needed for any description of atomic structure and dynamics, for the modeling of any plasma, and for synthetic spectra based on collisional-radiative modeling as a means to interpret and make use of observations of terrestrial and astrophysical plasmas (Träbert, 2014). Accurate measurements of transition rates of, in particular, exotic decay modes such as hyperfine induced (HFI) or two-photon transitions still pose a challenge for state-of-the-art atomic structure theory (Johnson, 2011;Fritzsche et al, 2015).…”

“…5. A particular class of exotic transitions, the two-photon E1M1 decay of Be-like ions in the metastable 2s2p 3 P 0 level has attracted considerable attention recently (Bernhardt et al, 2012(Bernhardt et al, , 2015bFritzsche et al, 2015). The lifetimes are unexpectedly long due to relativistic effects.…”

“…Studies of X-ray emission from HCIs have been found to be a unique tool for improving our understanding of the electron-electron (e-e) and electron-photon interactions in the presence of strong fields (Fritzsche et al, 2005(Fritzsche et al, , 2009. The x-ray spectroscopy of these systems showed that accurate energies and cross sections are obtained only if, apart from the static Coulomb repulsion among the electrons, the magnetic and retardation contributions to the electron-electron interaction as well as the leading quantum-electrodynamical effects are taken into account (Artemyev et al, 2013;Yerokhin et al, 2014;Fritzsche et al, 2015). In contrast to the x-ray spectroscopy, however, much less is known so far about how the magnetic and retarded interaction among the electrons affect their emission and, hence, the dynamics of electrons in strong fields.…”

Photorecombination of berylliumlike and boronlike silicon ions

“…Be-like ions are known to have long-lived 2s2p 3 P J levels (J = 0, 1, 2) which might have been present in the ion beam used for the measurements described here. The predicted lifetime of the 28 Si 10+ (2s2p) 3 P 0 , 3 P 1 and 3 P 2 levels are several 100 days [59], 2.747 µs and 0.4729 s [16] due to the dominant two-photon (E1M1), intercombination (E1), and magnetic quadrupole (M2) transitions, respectively. For nuclei with a nonzero magnetic moment, hyperfine quenching shortens the 3 P 0 lifetime by 6 orders of magnitude.…”

Absolute rate coefficients for photorecombination of beryllium-like and boron-like silicon ions

“…The predicted lifetime of the 28 Si 10+ (2s2p) 3 P 0 , 3 P 1 and 3 P 2 levels are several 100 days [59], 2.747 µs and 0.4729 s [16] due to the dominant two-photon (E1M1), intercombination (E1), and magnetic quadrupole (M2) transitions, respectively. For nuclei with a nonzero magnetic moment, hyperfine quenching shortens the 3 P 0 lifetime by 6 orders of magnitude.…”