A study of the A2Π-X2Σ+ and B2Σ+-X2Σ+ band systems of scandium monosulfide, ScS, using Fourier transform emission spectroscopy and laser excitation spectroscopy

Emission spectra of the A2Π3/2-X2Σ+ (0, 1), (0, 0), and (1, 0) bands and the B2Σ+-X2Σ+ (0, 1), (0, 0), (1, 0), (2, 0), and (3, 1) bands of ScS have been recorded in the 10 000-13 500 cm−1 region at a resolution of 0.05 cm−1 using a Fourier transform (FT) spectrometer. The A2Πr-X2Σ+ (1, 0) band as well as the B2Σ+-X2Σ+ (0, 0) and (1, 0) bands have been recorded at high resolution (±0.001 cm−1) by laser excitation spectroscopy using a supersonic molecular beam source. The FT spectral features range up to N = 148, while those recorded with the laser cover the “low-N” regions. The lines recorded with the laser exhibit splittings due to the 45Sc (I = 7/2) magnetic hyperfine interactions, which are large (∼6.65 GHz) in the X2Σ+ state and much smaller in the B2Σ+ and A2Π states. The energy levels were modeled using a traditional 'effective' Hamiltonian approach, and improved spectroscopic constants were extracted and compared with previous determinations and theoretical predictions.