Laboratory rotational spectrum of nickel monochloride in the ground electronic (2)Pi(3/2) state

The pure rotational spectrum of nickel monochloride in the (2)Pi (3/2) grou nd electronic state has been observed in the laboratory for the first time in the millimeter- and submillimeter-wave region. The NiCl radical was gene rated in a free-space absorption cell by a DC glow discharge in a mixture o f Cl-2 and Ar using a nickel cathode, from which nickel atoms were supplied by the sputtering reaction. The rotational, centrifugal distortion, and fi ne-structure constants were determined by a least-squares method using an e ffective Hamiltonian for a (2)Pi (3/2) electronic state.