Fe I Oscillator Strengths for Transitions from High-lying Even-Parity Levels

E. A. Den Hartog, M. P. Ruffoni, J. E. Lawler, J. C. Pickering, K. Lind, N. R. Brewer

Published 2014-09-29Version 1

New radiative lifetimes, measured to $\pm$ 5 % accuracy, are reported for 31 even-parity levels of Fe I ranging from 45061 cm$^{-1}$ to 56842 cm$^{-1}$. These lifetimes have been measured using single-step and two-step time-resolved laser-induced fluorescence on a slow atomic beam of iron atoms. Branching fractions have been attempted for all of these levels, and completed for 20 levels. This set of levels represents an extension of the collaborative work reported in Ruffoni et al. (2014). The radiative lifetimes combined with the branching fractions yields new oscillator strengths for 203 lines of Fe I. Utilizing a 1D-LTE model of the solar photosphere, spectral syntheses for a subset of these lines which are unblended in the solar spectrum yields a mean iron abundance of <log[{\epsilon}(Fe)]> = 7.45 $\pm$ 0.06.