Spectroscopic parameters of phosphine, PH3, in its ground vibrational
  state
  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 Delta(J) =
Delta(K) = 0 transitions between A1 and A2 levels, Delta(J) = 0, Delta(K) = 3
transitions as well as regular Delta(J) = 1, Delta(K) = 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 occured for the hyperfine parameters.
