High-resolution jet emission spectra of 12C18O in the 1380È1650 region of the 4th positive bands, Ó A 1% ] X 1&', have been recorded photographically and have been reduced to upper-state term values for low to medium rotational quantum numbers in the 10 lowest vibrational levels of A 1%. The deperturbation of the A state from spin-orbit and rotation-electronic interactions with singlet and triplet & and * states has established the percentage 1% character of the observed excited-state

more »

... levels. Dunham series expansion coefficients representing the deperturbed energies have also been determined.