Rotational dynamics of a diatomic molecular ion in a Paul trap

TL;DR

This paper models the rotational dynamics of a heteronuclear diatomic molecular ion in a Paul trap, highlighting how the permanent dipole moment influences ion trajectories and rotational states, diverging from atomic ion behavior.

Contribution

It introduces a combined classical-quantum model for molecular ion rotation in a Paul trap, revealing the impact of dipole coupling on motion and rotational states.

Findings

Dipole moment alters ion trajectories from classical Mathieu solutions.

Coupling affects quantum rotational states.

Rotational dynamics influence center-of-mass motion.

Abstract

We present models for a heteronuclear diatomic molecular ion in a linear Paul trap in a rigid-rotor approximation, one purely classical, the other where the center-of-mass motion is treated classically while rotational motion is quantized. We study the rotational dynamics and their influence on the motion of the center-of-mass, in the presence of the coupling between the permanent dipole moment of the ion and the trapping electric field. We show that the presence of the permanent dipole moment affects the trajectory of the ion, and that it departs from the Mathieu equation solution found for atomic ions. For the case of quantum rotations, we also evidence the effect of the above-mentioned coupling on the rotational states of the ion.