A study of the A²II/B²Σ⁺ - X ²Σ⁺ band systems of calcium monohydride (CaH) using a supersonic molecular beam source and laser-induced fluorescence detection

The high-resolution laser-induced fluorescence spectrum of a molecular beam sample of calcium monohydride (CaH) in the region of the strongly overlapped (1,0) A²II - X²Σ⁺ and (0,0) B ²Σ⁺ - X²Σ⁺ band systems near 630 nm and the (0,0) A²II - X²Σ⁺ band system near 690 nm have been recorded and analyzed. The spectral features exhibit a small splitting that is attributed to proton magnetic hyperfine interaction in the X²Σ⁺ (v = 0) state. The energy levels of the A²II(v = 0) vibronic state were modeled using a traditional "effective" Hamiltonian approach, whereas those for the interacting A²II(v = 1)/B²Σ⁺(v = 0) vibronic levels were modeled by augmenting the traditional effective Hamiltonian with terms to account for local perturbations. An interpretation of the field-free parameters is presented.