Fe II lifetimes and transition probabilities

Abstract

Fe II radiative lifetimes were measured applying the time-resolved nonlinear laser-induced fluorescence technique. We investigated 21 levels of up to 47 000 cm-1. The uncertainties are typically 2-3%. The lifetimes provide an improved absolute scale to our branching fractions which were measured with a Fourier transform spectrometer and a high-resolution grating spectrometer and which have been published earlier. We report absolute transition probabilities of 140 Fe II lines in the wavelength range 220-780 nm. The overall uncertainties are estimated to be 6% for the strong and up to 26% for the weak transitions. The results are compared with recent experimental data from the literature. Our large set of accurate data can be used for a reliability check of theoretical data calculated for iron abundances in astrophysical plasmas.