Rovibrational Transition Properties of System X 1 Σ + –A 1 Π of CO

The potential energy curves of the X 1 Σ + and A 1 Π states and the transition dipole moments between them were calculated using the internally contracted multireference configuration interaction (icMRCI) approach. To calculate the accurate rovibrational transition properties of the A 1 Π–X 1 Σ + system, we employed the experimental T e of the A 1 Π state and the R e of the two states to improve the reliability of the ab initio results. The transition energies, Einstein A coefficients, oscillator strengths, vibrational transition dipole moment matrix elements, and Franck–Condon factors of the rovibrational transitions of the A 1 Π–X 1 Σ + system were calculated at the rotational quantum number J ≤ 150 for the lower vibrational levels. The Einstein A coefficients of certain rovibrational transitions are large, suggesting that these transitions are strong and therefore, can be readily measured through spectroscopy. Comparison of the rovibrational transition properties calculated herein with the experimental results indicated an acceptable agreement, suggesting that the obtained results are accurate.