Jet-cooled laser-induced fluorescence spectroscopy of ScH: Observation of an Ω′=2−Ω″=1 transition

•Observation of (0,0) and (1,1) bands of the g3Φ2-a3Δ1 transition in ScH in a free-jet.•The first transition observed between the triplet-triplet manifolds.•Molecular constants of the a3Δ1 and g3Φ2 electronic states determined.•Rotational constants indicate perturbations in both states.

New bands of scandium monohydride at origins 17,914.5 and 17,942.3 cm−1 have been observed in a jet-cooled beam with laser-induced fluorescence spectroscopy. Mass-selected resonant photoionization spectroscopy also confirmed the carrier of the band as ScH. The rotational analysis indicated that both transitions at 17,914.5 and 17,942.3 cm−1 are of Ω′=2−Ω″=1 type with vibrational assignments (0,0) and (1,1) respectively. The assigned g3Φ2-a3Δ1 excitation is the first observed triplet-triplet transition in ScH.