A millimeter/sub-millimeter-wave spectroscopic study of the FeCl radical (X6Δi)

Pure rotational spectroscopy of the FeCl radical (X6Δi) has been carried out using millimeter/sub-millimeter direct absorption techniques. The species was created by the reaction of chlorine with iron vapor. All six spin-orbit components were observed in the majority of the twenty-one rotational transition recorded. Chlorine hyperfine structure was resolved in the Ω = 92 and 72 components, and lambda-type doubling observed in the Ω = 3212, and −12 ladders. The data were analyzed with a 6Δ Hamiltonian, and rotational, fine structure, lambda-doubling, and hyperfine parameters determined. The hyperfine and lambda-doubling interactions in FeCl appear to be different from those in the FeF radical.