Fermi Resonance in Linear Triatomic Molecules in Π Electronic States

The effect of Fermi resonance on the vibronic energy levels of linear triatomic molecules in Π electronic states has been considered, for states in which both the spin-orbit interaction and the Renner interaction are small compared to the frequency of the bending vibration. The essential difference between the results below and those for Fermi resonance in nondegenerate electronic states is the introduction of two Fermi interaction parameters W1 and W2, rather than one. Specific results are presented for the Fermi diad (100)—(020). The only experimental data available, those for the vibronic states of the A2Π electronic state of BO2, can be nicely fitted with the results of this paper.