Rotational, structural, ab initio, and semirigid bender analysis of the millimeter wave spectrum of H 2COHF

Abstract

The hydrogen-bonded species H 2COHF has been studied in a conventional microwave absorption cell. The dimer was produced under equilibrium conditions at −78°C from a mixture of H 2CO and HF. Spectra from H 2COHF, H 2CODF, and D 2CODF are reported. Rotational spectra from two low-energy excited vibrational states, which involve the hydrogen bond, have been observed. Structural analysis was performed by fitting rotational constants after correcting the observed rotational constants for contributions from the low-energy vibrational states. The semirigid bender model was fitted to the observed rotational structure of the bending vibrational levels. The bending potential function and the intermolecular distance were determined in the fittings. SCF ab initio calculations were used to model the bending vibrational dynamics and the potential functions of the three in-plane intermolecular vibrations.