“Hot” bands of CO and the effect of vibration-rotation interaction on the solar CO spectrum

Abstract

For the first overtone bands of CO, theoretical Herman-Wallis factors and experimental values show some inconsistencies for high excitation transitions. To resolve this problem, the relative band intensities, as well as the relative line intensities, are examined with CO lines in the solar infrared spectrum. The relative rotationless dipole-moment matrix elements and the Herman-Wallis factors for 2-0, 3-1, 4-2, 5-3 and 6-4 bands obtained from the solar CO spectrum are reasonably consistent with the theoretical predictions based on the dipole-moment function but disagree with results obtained in high-temperature emission measurements. It is shown that a reinterpretation of the high-temperature emission measurements is possible; the resulting Herman-Wallis factors become compatible with theoretical predictions as well as with the solar analysis.