Effective Rotational Potential of a Molecular Ions in a Plane Radio-Frequency Trap

A model of rotational potential that represents an analog of the pseudopotential for localization of a model of diatomic particle with rigid bond in a plane quadrupole radio-frequency trap is considered. It is shown that the effective rotational potential can be used to describe dynamics of various diatomic particles with different centers of mass and charges. Comparison of the model of pseudopotential for localization of a single ion and the proposed model of the effective rotational potential for diatomic structure is used to determine additional positions of quasi-equilibrium for the center of mass of the diatomic particle and orientation angle of the molecule. Additional positions of quasi-equilibrium substantially affect dynamics of charged structure localized in the field of a plane quadrupole ion trap.