Transition probabilities in Cr I

Abstract

We have measured branching fractions for 60 Cr I lines that originate from 14 different upper levels, with energies ranging from 3.3 to 6.9 eV. The measurements, obtained on the solar Fourier-Transform Spectrometer of the U.S. National Optical Astronomy Observatory on Kitt Peak, cover a wavelength range extending from c. 290 to 900 nm. The branching fractions, together with level lifetimes determined by use of laser excitation by Kwiatkowski et al., yield transition probabilities with an accuracy of c. 7 per cent. A comparison with the precision data determined in an absorption experiment at Oxford by Blackwell, Menon & Petford shows no systematic trends and thus provides for the first time an independent upper limit on the claimed uncertainty of the Oxford data.