A new method for calculating hyperfine splittings of strongly perturbed states: application to the a 3Π state of CH+

Abstract

A new method is presented for calculating nuclear hyperfine splittings of vibration–rotation levels for diatomic molecules. The method is appropriate for cases where there is a strong interaction between electronic states, and is applied to the near-dissociation levels of the a ³Π state of CH⁺. A set of adiabatic potential curves is generated which incorporates effects of spin–orbit, rotational and hyperfine coupling between electronic states. The hyperfine splitting of a given level is then calculated as the vibrational average of the hyperfine splitting of the appropriate potential curve. Comparisons are made with the hyperfine splittings observed in high-resolution ion-beam studies for this molecule.