The rotational spectrum of the NiS radical in the X3Σ− state

Abstract

The rotational spectrum of the NiS radical in the X³Σ⁻ state was observed by employing a source-modulation microwave spectrometer. The NiS radical was generated in a free space cell by a dc glow discharge in H₂S diluted with Ar. The nickel atoms were supplied by the sputtering reaction from a nickel cathode. Rotational transitions with J = 11–10 to 25–24 were measured in the region between 135 and 314 GHz. Rotational, centrifugal distortion and several fine-structure constants were determined by a least-squares analysis. Other spectroscopic parameters such as dissociation energy, vibrational wavenumber and equilibrium bond length were also derived from the determined molecular constants. Excitation energies of the lowest ³Π and ¹Σ⁺ states were estimated from the fine-structure constants, λ and γ.