A reanalysis of the molecular beam electric resonance Stark effect data for the a 3Π state of carbon monoxide

The highly precise measurements of Stark coefficients in the lambda doubling transitions of a 3Π CO obtained in previously published molecular beam electric resonance experiments have been reanalyzed. Certain perturbations between vibrational levels of the a 3Π and a′ 3Σ+ states that were neglected in the earlier treatment have been found to be important. An apparent error, by a factor of in the Stark matrix elements that were used in prior work, has also been corrected. The previously reported experimental determination of the dipole moment function of a 3Π CO is shown to be invalid. Thus, the relatively flat appearance of the dipole moment function found in previous ab initio studies may indeed be correct. The dipole moment in the a′ 3Σ+ state and the transition moment between the a 3Π and a′ 3Σ+ states are substantially revised to −0.79 and +0.64 D, respectively.