On the c3Π(v = 0) state of carbon monoxide

A full analysis of the near infrared c3Π-b3Σ+ (0-0) band is given and term values for both states determined. The c3Π (v = 0) state was jointly analysed with the perturbing k3Π (v = 2) state and data from the c3Π-X1Σ+ (0-0) transition and 3A band system were included. It is shown that the available data are consistent with the c3Π (v = 0) state having near Hund's case b coupling with a spin-orbit constant of A = 0.45 ± 0.02 cm−1, a homogeneous perturbation with the k3Π (v = 2) state, and Λ-type doubling arising predominantly from its interaction with the j3Σ+ state. A discrepancy with a more recent report of the 3A band system is identified and discussed. The perturbed b3Σ+ state term values are consistent with a previously reported five state interaction model.