Microwave spectrum of formaldehyde and its isotopic species in D, 13C, and 18O : Study of Coriolis resonance between ν4 and ν6 vibrational excited states

Abstract

In the investigation of the 8- to 370-GHz region 41 and 57 transitions have been assigned to ν 4 and ν 6 Coriolis-coupled states of H 2CO and D 2CO, respectively. The numerical analysis based on Watson's theory of centrifugal distortion coupled with the addition of Coriolis interaction allows us to obtain a set of parameters which fits the transitions well. The rotational spectrum of the ground state of H 2CO, D 2CO, HDCO, H 2 13CO, D 2 13CO, HD 13CO, H 2C 18O, and D 2C 18O have been reinvestigated and a set of parameters is obtained for each species. Some R A -type transitions of the ν 3 state of H 2CO and D 2CO have also been observed.