Effects of orbital angular momentum in CH2 The Renner-Teller effect

The vibrational and K-type rotational levels of the ã 1 A 1 and the ᵬ 1 B 1 state of CH 2 have been fitted by least squares to give a pair of Born-Oppenheimer potential curves for the combining electronic states. An accurate description of the effects of orbital angular momentum on the energy level positions has been obtained. We have been able to relate the force constants used in the calculation of the bond length variation in the semi-rigid bender model to the parameters derived from the deperturbation of the Fermi resonance interaction, and have shown that there is reasonable agreement between them. Finally we have been able to link the amount of unpaired angular momentum ⟨L z ⟩ produced by the vibronic coupling to the degree of magnetic activity observed in the vibronic sub-bands, and in rotational energy levels of the ã, v 2 = 0 state.