Coriolis interaction between vibration and rotation in symmetric top molecules

The effect of Coriolis perturbations on the perpendicular infra-red bands of symmetric top molecules is studied in the first approximation. The sum of the Coriolis coefficients for the vibrations in any symmetry class is shown to assume an extremely simple form, and its value is given for the general case. A straightforward method is described for the calculation of first-order Coriolis coefficients, and rules are derived whereby the rotational spacing of an overtone or combination band may be calculated from the Coriolis coefficients of the component vibrations.