Abstract
Selection rules and electric-dipole transition moments between rotational substates in excited vibrational states of spherical-top molecules have been derived. The explicit dependence of these moments on rotational and vibrational quantum numbers has been calculated. These results, which are generally applicable, have been used to analyze the concept of a multiple-photon pathway in the 3 “ladder” of SF6. It will be shown that some ladder schemes must have “rung gaps” in their sequence of proposed strongly allowed electric-dipole transitions.