Hexapole State-Selection and Beam Focus of Polar Top Molecules

We express a description of the state-selection role for a polar molecule in a hexapole electrostatic field. By a quantum mechanical treatment of the molecular Stark energy and a classical mechanical treatment for the molecular trajectory in the field, we present the calculated results of the different molecular rotational state selection and beam focus and discuss the influence of the high order Stark effect, the beam speed on the results for the symmetric top molecule CH₃CN, CH₃I, and the asymmetric top molecule CH₂F₂ in the hexapole field. The method established and results obtained can be taken as a guide for hexapole state selection and beam focus of polar top molecules.