Manipulating a beam of barium fluoride molecules using an electrostatic hexapole

TL;DR

This study demonstrates the use of an electrostatic hexapole lens to manipulate and focus a barium fluoride molecular beam, overcoming challenges posed by the molecule's properties, with implications for precision measurements.

Contribution

It introduces a method to control barium fluoride molecular beams using an electrostatic hexapole, including displacement and focusing capabilities, validated by experiments and simulations.

Findings

The low-field seeking molecules passing through a 4mm aperture increased by a factor of 12.

The molecular beam can be displaced by up to +/-5 mm using the hexapole.

Experimental results agree well with numerical trajectory simulations.

Abstract

An electrostatic hexapole lens is used to manipulate the transverse properties of a beam of barium fluoride molecules from a cryogenic buffer gas source. The spatial distribution of the beam is measured by recording state-selective laser-induced fluorescence on an emccd camera, providing insight into the intensity and transverse position spread of the molecular beam. Although the high mass and unfavorable Stark shift of barium fluoride pose a considerable challenge, the number of molecules in the low-field seeking component of the N=1 state that pass a 4 mm diameter aperture 712 mm behind the source is increased by a factor of 12. Furthermore, it is demonstrated that the molecular beam can be displaced by up to +/-5 mm by moving the hexapole lens. Our measurements agree well with numerical trajectory simulations. We discuss how electrostatic lenses may be used to increase the sensitivity of beam experiments such as the search for the electric dipole moment of the electron.