Study of the spectrum of the Kr-CO weakly bound molecular complex in the millimeter-wavelength range

The rotational spectrum of the weakly bound Kr-CO molecular complex formed in a pulsed molecular jet has been measured in the frequency range 112–150 GHz on an intracavity orotron-based spectrometer. The measured b-type transitions include the R branch of the band K = 1-0 with the rotational numbers J from 16 to 25 and the P branch of the band K = 2-1 with the rotational numbers J from 13 to 17. For the K = 1-0 band, we succeeded in recording transitions in complexes that consist of all stable Kr isotopes, i.e., 84Kr-CO, 86Kr-CO, 82Kr-CO, 83Kr-CO, and 80Kr-CO. For the K = 2-1 band, we observed transitions in the two most abundant isotopologues, 84Kr-CO and 86Kr-CO. The obtained data were used to determine the rotational and centrifugal constants of the Kr-CO complex.