HYPERFINE INTERACTIONS AND LAMBDA-TYPE DOUBLING IN MICROWAVE SPECTRUM OF NS RADICAL

Strong absorption lines due to free NS radicals have been observed by means of Stark modulated microwave spectrometers, in the discharge products of a mixture of nitrogen and sulfur dichloride or sulfur monochloride. The rotational transitions J = 3 2 ← 1 2 in the 2Π 1 2 state as well as J = 5 2 ← 3 2 both in the 2Π 1 2 and 2Π 3 2 states are analyzed to investigate the Λ-type doubling and the hyperfine interactions in two isotopic species 14N32S and 14N34S. The parity considerations lead to negative sign of the Λ-type doubling parameter αp, which indicates that the dominant perturbing state is a 2Σ- state not identified yet. Relative magnitudes of hyperfine constants of NS are very similar to those of NO, although their absolute values in the former are consistently smaller than in the latter. The rotational constant B0 = 23156.01 ± 0.16 MHz obtained in the present analysis, combined with αeB from the γ-band analysis, gives an accurate equilibrium internuclear distance re = 1.4938 ± 0.0002 A ̊. The electric dipole moment is determined to be 1.81 ± 0.02 Debye in the 2Π 1 2 state by the Stark effect measurements. © 1969.