Rotational Analysis of the LiHg 22Π3/2-X2Σ+ 1/2 (ν′ = 0 ← ν″ = 0, 1, 2) Vibronic Bands

We present a complete analysis of the previously reported LiHg 2²Π_3/2-X²Σ⁺ excitation spectrum [X. Li, P. Pircher, D. Gruber, and L. Windholz, Chem. Phys. Lett. 263, 463 (1996)]. The ν′ = 0 - ν″ = 0, 1, 2 vibronic bands are analyzed and the rotational transitions are identified. The assigned rotational transitions are initially fitted on a band-to-band basis. A global fit is performed afterwards for all the known vibronic transitions of the LiHg molecules. In the fit the ground state molecular constants are separated into spin-rotation coupling terms and Dunham-type coefficients. The obtained Dunham coefficients are used to derive the molecular potential for the ground electronic state using the inverted perturbation approach (IPA). The equilibrium bond length was found to be 2.9528(6) Å for the LiHg ground state.