Stark-selected beam of ground-state OCS molecules characterized by revivals of impulsive alignment

TL;DR

This study demonstrates the quantum-state-specific deflection of OCS molecules using an electrostatic field, and characterizes the ground-state molecules through impulsive alignment and revival measurements, achieving high state purity and alignment.

Contribution

It introduces a method to select ground-state molecules via electrostatic deflection and characterizes their alignment dynamics, enhancing state purity in molecular beams.

Findings

Ground-state molecules can be effectively separated by deflection.

Selected molecules show high alignment ( extasciitilde 0.84) and purity (>92%).

Impulsive alignment revivals reveal quantum state composition.

Abstract

We make use of an inhomogeneous electrostatic dipole field to impart a quantum-state-dependent deflection to a pulsed beam of OCS molecules, and show that those molecules residing in the absolute ground state, $X ^1\Sigma^+$, $\ket{00^00}$, J=0, can be separated out by selecting the most deflected part of the molecular beam. Past the deflector, we irradiate the molecular beam by a linearly polarized pulsed nonresonant laser beam that impulsively aligns the OCS molecules. Their alignment, monitored via velocity-map imaging, is measured as a function of time, and the time dependence of the alignment is used to determine the quantum state composition of the beam. We find significant enhancements of the alignment (\costhetasqtd $= 0.84$) and of state purity ($> 92$%) for a state-selected, deflected beam compared with an undeflected beam.