Microwave spectrum of PHD: hyperfine structure

Abstract

The rotational spectrum of the monodeuterated PH 2 radical was studied using a source-modulated submillimeter-wave spectrometer. The PHD radical was generated in a free space absorption cell by a dc-glow discharge in a gas mixture of PH 3 and D 2. Six a-type and 20 b-type rotational transitions were observed in the frequency region of 170–670 GHz. Hyperfine structure due to the deuterium nucleus was resolved only in the rotational transitions of 1 11–0 00 and 1 10–1 01 and in the low F 2 components of N=2–1 transitions. A total of 219 spectral lines were measured of which 145 were analyzed by least-squares methods. These yielded 34 precise molecular constants including the hyperfine coupling constants of phosphorus, hydrogen, and deuterium. The principal axes and principal values of the magnetic dipole coupling tensors of hydrogen in PH 2 and deuterium in PD 2 were derived from the observed values of PHD, PH 2 and PD 2. The principal axis of the hydrogen magnetic dipole coupling tensor in PH 2 makes an angle of 2.29° with the PH bond and its T σ and T ⊥ principal values are determined to be 12.93 and −18.39 MHz, respectively.