The pure rotational spectra and hyperfine constants of SbN and SbP

The pure rotational spectra of antimony mononitride, SbN, and antimony monophosphide, SbP, have been recorded within the frequency range 6-26 GHz, using a cavity pulsed jet Fourier transform microwave spectrometer. The molecules were prepared by laser ablation of Sb and reaction of the resulting plasma with suitable precursors in the backing gas of the jet. For SbN the J = 1-0 transition was measured for the vibrational ground state of four isotopomers, two of which were also seen in the v = 1 excited state. For SbP the J = 1-0 and 2-1 transitions have been observed for two isotopomers in the ground plus v = 1 and v = 2 excited vibrational states. Accurate spectroscopic constants, including Born-Oppenheimer breakdown terms for Sb and N, have been obtained from the spectra. Precise equilibrium bond lengths r(e) have been determined. Hyper. ne constants including nuclear quadrupole coupling constants and nuclear spin-rotation constants have been evaluated for both molecules, and are compared with the results of density functional calculations.