Quadrupole Hyperfine Structure in the Microwave Spectra of Phosphorous Trichloride and Phosphoryl Chloride

The quadrupole hyperfine structures of the low rotational transitions in P35Cl3 and PO35Cl3 have been examined. Calculations of the hyperfine splitting and the Stark effect in the J = 1→ 2 transition have been made and compared with the experimental results. Measurements of the separation of the two strongest hyperfine components yielded the values −53.3 ± 1.0 and −55.4 ± 1.2 Mc/sec for the P–Cl bond axis quadrupole coupling constants eqQ in the molecules P35Cl3 and PO35Cl3, respectively. The Stark effect in the J = 1 → 2 and J = 2 → 3 transitions was analyzed to obtain the values 0.56 ± 0.02 and 2.54 ± 0.04 D for the dipole moments of PCl3 and POCl3, respectively. A phase‐lock klystron stabilization technique was used in recording the spectra to improve the resolution of the spectrograph.