Microwave spectrum of methylene fluoride- d 2, CD 2F 2 in the excited vibrational states

Abstract

The rotational spectra of 12CD 2F 2 in the ν 2, ν 3, ν 4, 2 ν 4, ν 5, ν 7, ν 8, and ν 9 states were observed and assigned. Weak Coriolis interactions between ν 3 and ν 7, ν 3 and ν 9, and ν 5 and ν 7 were analyzed using approximate expressions for the rotational energy levels. The resonance between the ν 2 and the ν 8 state was found much stronger, and an effective two-dimensional Hamiltonian with the Coriolis term in the off-diagonal block was set up to analyze the spectra. The effect of the Fermi resonance between ν 3 and 2 ν 4 was found to be very small. The ground-state spectrum of 13CD 2F 2 was observed and the rotational constants and the centrifugal distortion constants were determined. The data on 12CD 2F 2 and 12CDHF 2 were also improved very much in accuracy. The Coriolis coupling constants and the differences between two vibrational levels in resonance, which were determined by the analysis of the satellite spectra, are in good agreement with those obtained from vibrational spectra, except for the ν 2 band center, which is revised to 1170.3 cm −1. The force constants were also checked using the centrifugal distortion constants of 12CD 2F 2, 13CD 2F 2, and 12CHDF 2.