Accurate transition rates for the $5p-5s$ transitions in Kr I

Branching fractions were measured for electric-dipole transitions from the $5p$ upper levels to the $5s$ levels in neutral krypton atoms. The measurements were made with a wall-stabilized electric arc and a 2-m monochromator for the spectral lines in the visible, and with a hollow cathode lamp and the NIST 2-m Fourier-transform spectrometer for the lines in the near infrared. A semiempirical calculation, based on accurately known lifetimes for six upper levels, was used to calculate lifetimes for which accurate measurements do not exist. This resulted in a complete set of lifetimes for all $5p$ levels. Branching fractions and lifetimes were used to calculate transition rates for the $5p-5s$ transitions. The relative uncertainties of the transition rates range from less than 1% for the strongest lines to about 10% for the weakest lines. Our data also reveal that most of the previous measurements appear to have been affected by opacity effects in the light sources.