A high-resolution analysis of the C A12–X A12 transition of CaNH2: Pure precession in polyatomic molecules

The high resolution spectrum of the 000 vibronic band of the C̃ A12–X̃ A12 transition of CaNH2 was recorded with a laser ablation/supersonic molecular beam spectrometer. Approximately 140 lines of the Ka′=0←Ka″=0 and the Ka′=1←Ka″=1 sub–bands were measured and combined with the previous à B22–X̃ A12 and B̃ B12–X̃ A12 results. A global fit of the data was carried out and the effective spectroscopic constants for the X̃, Ã, B̃, C̃ states are reported. A complete set of spin–rotation constants (εαα’s) are now available for the à B22, B̃ B12 and C̃ 2A1 states. The unpaired electron in these three excited states can be considered to be located in three p–orbitals (px,py,pz) centered on the metal atom. The simple pure precession model provides estimates for the 9 spin–rotation parameters in the Ã, B̃, and C̃ states.