Rotational state detection of electrically trapped polyatomic molecules

TL;DR

This paper presents a novel method for detecting the internal rotational states of polyatomic molecules trapped electrically, overcoming limitations of traditional spectroscopic techniques by using state-selective removal in a specially designed trap.

Contribution

It introduces a new approach for rotational state detection in polyatomic molecules using state-selective removal in a homogeneous electric trap, enabling discrimination of all rotational quantum numbers.

Findings

Successfully discriminated all rotational quantum numbers including M-substates.

Demonstrated the feasibility of state detection without traditional spectroscopic methods.

Utilized a unique trap design with homogeneous fields for precise state discrimination.

Abstract

Detecting the internal state of polar molecules is a substantial challenge when standard techniques such as resonance-enhanced multi photon ionization (REMPI) or laser-induced fluorescense (LIF) do not work. As this is the case for most polyatomic molecule species, we here investigate an alternative based on state selective removal of molecules from an electrically trapped ensemble. Specifically, we deplete molecules by driving rotational and/or vibrational transitions to untrapped states. Fully resolving the rotational state with this method can be a considerable challenge as the frequency differences between various transitions is easily substantially less than the Stark broadening in an electric trap. However, making use of a unique trap design providing homogeneous fields in a large fraction of the trap volume, we successfully discriminate all rotational quantum numbers, including the rotational M-substate.