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?C150 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.