The c3Π – b3Σ+ transition of CO near 8245 cm−1

A transition between two high-lying electronic states of CO, c3Π – b3Σ+, has been observed by high resolution Fourier transform spectroscopy, in the near infrared, around 8245 cm−1. The triplet splittings of both c3Π and b3Σ+ have clearly been observed. The value A = 1.504(12) cm−1 has been determined for c3Π and confirms the previous direct determination of Klopotek and Vidal (J. Opt. Soc. Am. B, 2, 869 (1985)). Because these states were found to be heavily perturbed, only the analysis and effective rotational constants are reported.