A theoretical investigation of the radiative properties of the CN red and violet systems

The radiative properties of the CN red and violet systems were investigated theoretically using the CASSCF method. The transition moments between the states were obtained using wave functions with orbitals separately optimized for each state. The computed radiative lifetimes for the different vibrational levels of the A 2Pi state were found to be in reasonably good agreement with measurements using the high frequency deflection technique, although noticeable deviations were found for the lowest vibrational levels. For v' = O, the calculations were found to agree well with a laser measurement. A reinterpretation is proposed for a recent analysis of the CN red system in the solar spectrum where large deviations from laboratory measurements were found. It is shown that if a lower dissociation energy for CN is used, the lifetimes obtained will be in much better agreement with the calculated values. Fairly large differences were also obtained between these results and recent CI calculations. Excellent agreement between the calculated lifetimes and the very reliable experimental measurements were obtained for the violet system.