Theoretical study of the spectroscopy and radiative transition properties of NS

•Accurate spectroscopic constants of these low-lying states of NS are obtained.•TDM and radiative lifetime for the B2Π, B′2Σ+ and G2Σ− states have been determined.•The F-C factors of the B2Π are in good agreement with the corresponding RKR data.•The B′2Σ+ state possesses a barrier in the PECs, located at about 2.16 Å.

The low-lying electronic states (X2Π, a4Π, b4Σ−, B2Π, 12Φ, A2Δ and B′2Σ+) of the NS molecule are computed at the AV5Z/CASSCF/MRCI+Q+DK level of theory. The potential energy curves are presented for these states; the corresponding spectroscopic constants are reported. Electronic transition moment functions, Einstein coefficients, Franck-Condon factors and radiative lifetimes for the B2Π-X2Π, B′2Σ+-X2Π and A2Δ-X2Π system have been calculated. The F-C factors of the B2Π are in good agreement with the corresponding RKR data. The B′2Σ+ state possesses a barrier in the potential energy curve, located at about 2.16 Å. The height of the barrier is predicted to be 7890 cm−1.