Microwave Spectrum of Formaldehyde II. Molecular Structure in the Ground State

Rotational constants for the isotopic formaldehyde molecules H 2 CO, H 2 C 13 O, H 2 CO 18 , HDCO and D 2 CO were determined from the parameters used in the analysis of K -type doubling spectra and the frequencies of 1 01 ←0 00 transitions. In the cases of isotopic species for which the R -branch transitions were not measured, the calculated inertia defect was used in the determination of the rotational constants. From the rotational constants, the zero-point structure of formaldehyde molecule, r z , was determined by a new method taking into account the zero-point vibration-rotation interaction and electronic interaction. The following zero-point molecular structure was obtained