A cold beam of BaOH molecules using a water-vapour seeded neon gas

TL;DR

This paper demonstrates the production of a cold BaOH molecular beam using a cryogenic buffer-gas source with water vapor seeding, achieving high flux and suitable velocity for fundamental symmetry studies.

Contribution

It introduces a novel method for producing a cold BaOH beam with enhanced flux via laser excitation inside a cryogenic buffer-gas cell.

Findings

BaOH beam flux is increased 11-fold with laser excitation.

The molecular beam has an average velocity of about 180 m/s.

The beam intensity is comparable to cryogenic BaF beams.

Abstract

In this paper we report on the production and characterization of a cold beam of BaOH molecules using a cryogenic buffer-gas beam source. BaOH is a highly suitable molecule for studies of the violation of fundamental symmetries, such as the search for the electron's electric dipole moment. BaOH molecules are synthesised inside the cold source through laser ablation of a barium metal target while water vapor is seeded into the neon buffer gas. The BaOH flux is significantly enhanced ($\sim$11 times) when laser-exciting the barium atoms inside the buffer-gas cell on the $^1\mathrm S_0 - ^3\mathrm P_1$ transition. A similar enhancement has been reported for other alkaline-earth(-like) monohydroxides. For typical source conditions, the molecular beam has an average velocity of $\approx180$ m/s and an intensity of $\sim 10^{9}$ molecules s$^{-1}$ in $N=1$, which is comparable to that of cryogenic BaF beams.