Hyperfine spectroscopy of the 1s5−2p9 transition of A39r

We report on the first experimental determination of the hyperfine structure of the 1s5−2p9 transition in A39r. We give a detailed description of the sample preparation, spectroscopy cell cleaning, and spectroscopic setup. The resulting set of parameters consists of the hyperfine constants of the levels involved and the isotopic shift between A39r and A40r. With the achieved precision all laser frequencies necessary for the implementation of atom trap trace analysis for A39r, i.e., laser cooling and repumping frequencies, are now known.