Spectroscopic parameters of phosphine, PH3, in its ground vibrational state

•A combined fit of ground state rotational data was carried out.•Improved spectroscopic parameters have been obtained.•Predictions have been generated e.g. for planetary observations.

The ground state rotational spectrum of PH3 has been reanalyzed taking into account recently published very accurate data from sub-Doppler and conventional absorption spectroscopy measurements as well as previous data from the radio-frequency to the far-infrared regions. These data include ΔJ=ΔK=0 transitions between A1 and A2 levels, ΔJ=0, ΔK=3 transitions as well as regular ΔJ=1, ΔK=0 rotational transitions. Hyperfine splitting caused by the 31P and 1H nuclei has been considered, and the treatment of the A1/A2 splitting has been discussed briefly. Improved spectroscopic parameters have been obtained. Interestingly, the most pronounced effects occurred for the hyperfine parameters.