1,3-Propanediol millimeter wave spectrum: Conformers I and II

Abstract

We present a new study of the millimeter wave spectrum of the lowest two conformers of the 1,3-propanediol (CH2OHCH2CH2OH) molecule. The new measurements involving rotational transitions with J up to 65 and Ka up to 30 for conformer I and J up to 59 and Ka up to 29 for conformer II have been carried out between 49 and 237GHz using the Kharkov millimeter wave spectrometer. The new data were combined with previously published measurements and fitted using a model that assumes a symmetric potential energy surface with two minima between which the system tunnels. The final fit included 19 parameters for conformer I and 23 parameters for conformer II with weighted root-mean-square deviations of 0.81 and 0.73 achieved for datasets consisting of 3384 and 2947 line frequencies belonging to the ground states of conformer I and conformer II, respectively. The millimeter wave spectra of both conformers reveal a rather strong influence of the Coriolis type perturbation, which previously was not taken into account in the analysis of the 1,3-propanediol spectrum.