Rovibrational spectra of diatomic molecules in strong electric fields

We investigate the effects of a strong static electric field on the rovibrational spectra of diatomic heteronuclear molecules in a ¹Σ⁺ electronic ground state. Using a hybrid computational technique combining discretization and basis set methods the full rovibrational equation of motion is solved. As a prototype for our computations we take the carbon monoxide molecule. For experimentally accessible field strengths we observe that while low-lying states are not significantly affected by the field, for highly excited states strong orientation and hybridization are achieved. We propose an effective rotor Hamiltonian, including the main properties of each vibrational state, to describe the influence of the electric field on the rovibrational spectra of a molecular system with a small coupling between its rotational and vibrational motions. This effective rotor approach goes significantly beyond the rigid rotor approach and is able to describe the effect of the electric field for highly excited states.