Measured Level Lifetimes for the Coronal Transitions of F[CLC]e[/CLC] [CSC]x[/CSC] and F[CLC]e[/CLC] [CSC]xiv[/CSC]

Abstract

In a laboratory study, the lifetimes of the P levels producing the coronal transitions of Fe x and Fe xiv have 2 been measured. The fluorescence from the metastable levels, which were populated when the ions were produced in a source of multiply charged ions, was studied after the selected ions were injected into an electrostatic ion trap. The results are t(Fe x, 3s 3p) ϭ ms and t(Fe xiv, 3s 3p) ϭ ms. The 2 5 2 o 2 2 o P 13.64 ‫ע‬ 0.25 P 17.52 ‫ע‬ 0.29 1/2 3/2 data significantly reduce the uncertainty of the lifetimes when compared with existing theory.

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

“…Both earlier experiments on Fe X used an electrostatic ion trap and found data that either disagreed with theory (Moehs and Church 1999) or featured just a few results with uncertainties from 10 to 30% (Moehs et al 2000), which are of limited value. This uncertainty is particularly important if one decay component derived from one observation is then used to adjust and interpret fit results obtained on another data set (Moehs et al 2000).…”

“…Three sets of results from an electrostatic ion trap are available that give lifetimes for ground configuration (3p) and excited configuration (3d) levels in Fe X to Fe XIV (Moehs and Church 1999, Moehs et al 2000. However, measurements using a heavy-ion storage ring (Doerfert et al 1997, Träbert et al 1999a, 1999b) may well be expected to do better than those with respect to both systematic error and precision of the lifetime determination (this paper).…”

Lifetimes and branching fractions of the high angular momentum states of aluminium-like iron group elements

“… the laser‐produced plasma measurements by Redfors & Litzen (1989) for the low‐lying n = 3 levels of Ca viii –Ni xvi ; the beam–foil experiments by Träbert et al (1993) for the 3 s 3 p 3 d 4 F levels of Ti x , Fe xiv and Ni xvi ; the electron beam ion trap (EBIT) experiments by Moehs & Church (1999) and by Beiersdorfer, Träbert & Pinnington (2003) on the transition rate of the coronal transition of Fe xiv ; the heavy‐ion storage ring experiment by Träbert (2004) for the transition rates of the coronal lines of Fe x and Fe xiv ; and various others. …”

“…the electron beam ion trap (EBIT) experiments by Moehs & Church (1999) and by Beiersdorfer, Träbert & Pinnington (2003) on the transition rate of the coronal transition of Fe xiv ;…”

“…However, despite all the effort to understand the excitation and decay of the (40) low‐lying levels of the aluminium‐like ions, there still remain a number of questions on the excitation and decay of the aluminium‐like ions. For the E1 forbidden transition between the two 2 P 1/2 and 2 P 3/2 fine‐structure levels of the 3 s 2 3 p ground configuration, for instance, there is not only a quite sizeable deviation between the computations by Froese Fischer & Liu (1986) and Bhatia & Kastner (1993), but also a remarkable discrepancy of 5 per cent between two of the high‐resolution experiments by Moehs & Church (1999) and those by Beiersdorfer et al (2003). In addition, most of the available experiments and computations focused on the E1 allowed transitions which connect the levels with angular momenta J = 1/2, 3/2 and 5/2, while neither the E1 forbidden transitions nor the branching fractions have been studied systematically for the J = 7/2 and 9/2 metastable levels.…”