Anomalous Centrifugal Distortion Coefficients in Linear Polyatomic Molecules

The theory of the effect of resonance, in particular Fermi resonance and l-type resonance, on the effective centrifugal distortion coefficient of a molecule for a given vibration state is developed. The theory is applied to certain cases where l-type resonance occurs and to certain cases where both l-type resonance and Fermi resonance occur. No instances appear to have been investigated where Fermi resonance occurs without l-type resonance being present. The agreement between the theory and the experimental results appears to be satisfactory to the approximation of the theory.