Laser-induced fluorescence spectroscopy of NCS in a free jet expansion

Laser-induced fluorescence excitation spectra have been recorded for many vibronic transitions of the A(2Pi)--X(2Pi) and B(2 Sigma+)--X(2Pi) systems of NCS under supersonic free jet expansion conditions. New assignments have been made for many of these bands and several of the assignments from previous work have been revised. Vibronic energies have been determined for levels involving excitation of all three vibrational modes in the ground electronic state and both excited electronic states. A detailed rotational and vibrational analysis has been carried out for levels involving excitations of the two stretching modes and the many rotational and potential function constants have been determined for the A and X states. The variation of the spin--orbit constant with vibrational level has also been investigated. Results of this paper provide the ground work for a detailed analysis of the Renner--Teller effect in the bending vibrational mode of this radical for both the X2(Pi) and A(2Pi) states to appear in a forthcoming paper. They also provide a spectroscopic database for future dynamical and kinetics studies of processes involving this radical