Deperturbation of D1Πv = 4 level of ScF molecule: Characterization of the 3Πperturber from analyses of D1Π-X1Σ+ 4-2 and D1Π-A1Δ 4-4 LIF transitions

High resolution emission spectra of ScF molecule have been observed in the region of 21 120-21 300 cm−1 and of 15 640-15 710 cm−1. The rotational structures in 4-2 band of D1Π-X1Σ+ and in 4-4 band of D1Π-A1Δ were assigned. Rotational analysis reveals the presence of localized perturbations in the upper state D1Π v = 4 level at different values of J for the two parity sublevels, e and f. These perturbations are interpreted as the consequence of a spin-orbit interaction between D1Π state and a triplet state of 3Π symmetry. A matrix model describing the energies within the two interacting levels, has been used to fit term-values. Spectroscopic constants are obtained for A1Δ v = 4, D1Π v = 4 and for the 3Π perturbing level. The magnitude of the spin-orbit interaction is estimated.