Microwave spectra of the (HF) 2, (DF) 2, HFDF, and DFHF hydrogen-bonded complexes

Abstract

The microwave spectra of the tunneling-rotation bands of the hydrogen-bonded complexes (HF) 2 and (DF) 2 have been measured in the 50- to 126-GHz region. In addition, the pure rotation spectra of both the HFDF and DFHF molecules have been obtained. Transitions with K = 0 through K = 2 have been observed for all isotopic species. The hydrogen fluoride dimer is a very nonrigid molecular species. In order to fit the observed transitions adequately, empirical expressions for the energy levels were used, and each K subband was separately fitted. Constants obtained from a Padé approximant fitting of the microwave data of (HF) 2 together with infrared ground state combination differences are given.