Energy levels, lifetimes and branch fractions for Fe XI

Abstract

We present transition energies, probabilities and branching ratios for the electric dipole allowed (E1) and forbidden (M1, E2, M2) lines of the 3s23p4, 3s3p5 and 3s23p33d configurations of Fe xi. Large‐scale multiconfiguration Dirac–Fock wavefunctions are applied to include the effects of relativity, correlation and rearrangement of the electron density consistently within the same (computational) model. From the transition probabilities, lifetimes of the 46 lowest‐lying excited levels are derived, and the prospects for experimental verification are discussed. An M2 transition is identified in the solar extreme ultraviolet spectrum.

M1/E2 transition rates in FeXthrough FeXIIImeasured at a heavy-ion storage ring

“…For the time being, we quote the result with an overall uncertainty that corresponds to about three times the statistical uncertainty. Yet another 3d level, 3 G 5 , has been predicted to feature a lifetime near 100 ms (Mason and Nussbaumer 1977, Bhatia and Doschek 1996, Fritzsche et al 2000. This level radiates at two wavelengths (154 and 432 nm) that are not covered here.…”

“…The additional evidence from the data channels between ion expulsion and fresh injection points to the longer lifetime value. However, this decay component probably represents two levels ( 3 G 4 and 1 G 4 ), with major decay branches near 274 and 279 nm, respectively, and predicted lifetimes that range from 80 and 46 ms (Mason and Nussbaumer 1977) to 43 and 16 ms (Fritzsche et al 2000). The experimental result points to the first (and earlier) calculation; however, it is practically impossible to separate, in the multi-exponential decay curve analysis, two decay components that differ in their characteristic time constant by only a factor of two-while a third component and some background contribution are present as well.…”

“…(There are of the order of 30 levels in each of the ions investigated, of which only a few are so long-lived as to be of interest for the present study.) For iron, the heaviest element that appears with a relatively high abundance in the Sun, most of the 3s 2 3p 4 3d levels of Fe X are known by now Corliss 1988, Träbert 1998), but only about half of the corresponding 3s 2 3p 3 3d levels in the neighbouring Fe XI system (Fritzsche et al 2000). Various prominent transitions of Fe X (from low-J 3s 2 3p 4 3d levels) fall into the extreme ultraviolet (EUV) range that has been repeatedly studied by ever-better resolving spectrographs on a variety of spacecrafts aimed at the Sun.…”

Experimental and theoretical study of the Auger cascade following 3d→5p photoexcitation in Kr

“…To keep the present computations feasible and to include the lifetime interference effects, we limited ourselves to the contributions of a few strong mixing configurations in the representation of both the intermediate and final states (see below). No attempt has been made to incorporate all (virtual) single and double excitations within the 4l and 5l layer as it became a standard for the computation of oscillator strengths and lifetimes in recent years (Fritzsche et al 2000a(Fritzsche et al , 2000b. For several open shells such a systematic treatment results in wavefunction expansions which are infeasible until now.…”

EUV Beam-Foil Spectra of Titanium, Iron, Nickel, and Copper

“…Theory [123] suggests that these belong to intercombination decays of sextet levels in P-like ions. Decays of three 3d J = 7/2 levels in such P-like ions have been discussed in [60], and the corresponding levels in S-like ions have been discussed in [124]. These levels are long lived because they differ by more than two units in total angular momentum from the J = 3/2 ground state, and thus they cannot decay there by an electric dipole transition.…”