Inverted perturbation approach (IPA) potentials and adiabatic corrections of the X 1Σ+ state of the lithium hydrides near the dissociation limits

Abstract
Laser‐induced fluorescence (LIF) spectra of the AX system of the LiH isotopes, excited by the UV lines of an argon and a krypton ion laser, were observed and analyzed. Three long LIF series of different LiH isotopes were taken with a 3.4 m high resolution spectrograph. The results were combined with previous experimental data to study the breakdown of the Born–Oppenheimer approximation in the X 1Σ+ electronic ground state of the isotopic LiH molecules. Using a quantum mechanical variational method, potential energy curves of the four LiH isotopes were extended almost up to the dissociation limits.