Jet-cooled laser-induced fluorescence spectroscopy of LaH: Observation of new excited electronic states

Jet-cooled laser-induced fluorescence spectra of LaH molecules in the range 15 500–18 700 cm−1 showed four new vibronic bands. Rotational analysis confirmed a 1Σ+ symmetry for the ground state, identified a 0+(3Σ−) electronic state at 15622.9(1) cm−1 via intercombination transition observed for the first time in LaH and two more excited electronic states with Ω = 1 at 17397.9(1) and 17549.0(1) cm−1. Also observed the transition of type Ω′ = 0–Ω″ = 1 with band origin at 18508.8(1) cm−1. Comparison of the present data with earlier ab initio results indicated the overestimation of calculated energies and internuclear distances for the ground and excited electronic states.