Emission spectra of calcium dimer. The A 1∑u+ − X 1∑g+ system

The A 1∑u+−X 1∑ g+ spectral system of Ca2 has been studied in two independent experiments. The collision-induced fluorescence due to this band was investigated following the resonant excitation of the 4s4p 3P1 metastable state of calcium using a Nd : YAG laser pumped dye laser. In another experiment, a low current glow discharge in calcium vapor was used. We have assigned 86 spectral lines to this band system for vibrational quantum numbers (v′ = 10–13 and v″ = 0) by applying a Dunham type analysis. The A 1∑u+ state dissociation energy D′e is estimated to be ~ 8693.6 ± 1 cm−1. The processes involved in the collisional excitation of the upper molecular state are discussed.