A study of the A2Π/B2Σ+ – X2Σ+ 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) A2Π – X2Σ+ and (0,0) B2Σ+ – X2Σ+ band systems near 630 nm and the (0,0) A2Π – 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 A2Π(v = 0) vibronic state were modeled using a traditional "effective" Hamiltonian approach, whereas those for the interacting A2Π(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.Key words: calcium monohydride, molecular beam, fluorescence.