Lifetimes, branching ratios, and transition probabilities in Co ii

Abstract

The radiative lifetime of 14 levels in the z^5F, z^5D, and z^5G terms of Co ii have been measured with use of time-resolved laser fluorescence spectroscopy with a Co+-ion beam. Our lifetime values are shorter by 15–50 % than earlier results from beam-foil time-of-flight measurements. The lifetimes were converted to 41 individual transition probabilities with use of branching ratios measured on spectra recorded with the 1-m Fourier-transform spectrometer at the Kitt Peak National Observatory. On average our transition probabilities agree with those of Kurucz and Peytremann; for ΔS=1 transitions their calculated values are lower than our experimental results by a factor of ∼(1/4).