2001ApJ...551L.199Y

The pure rotational spectrum of nickel monochloride in the ²Π_3/2 ground electronic state has been observed in the laboratory for the first time in the millimeter- and submillimeter-wave region. The NiCl radical was generated in a free-space absorption cell by a DC glow discharge in a mixture of Cl₂ and Ar using a nickel cathode, from which nickel atoms were supplied by the sputtering reaction. The rotational, centrifugal distortion, and fine-structure constants were determined by a least-squares method using an effective Hamiltonian for a ²Π_3/2 electronic state.