SUBMILLIMETER-WAVE SPECTRA OF THE PH AND PD RADICALS IN THE 3-SIGMA- STATE

The lowest rotational spectral lines of the PH and PD radicals in their X 3SIGMA- ground vibronic state were observed by submillimeter-wave spectroscopy using a source-modulated system combined with a glow discharge free-space cell. The PH or PD radical was generated by the reaction of red phosphorus with dc glow discharged H-2 or D2 ps. Twenty fine and hyperfine components of the N=1-0 transition of PH were measured in the frequency region of 423 to 553 GHz, and 50 components of the N=1-0 and 2-1 transitions of PD in the region of 181 to 523 GHz. The molecular constants, including the rotational constants, the spin-spin coupling constants with their centrifugal distortion terms, and the hyperfine coupling constants associated with the phosphorus, hydrogen and deuterium nuclei, were precisely determined by least-squares fitting to the observed spectral lines.