Enhanced Yield from a Cryogenic Buffer Gas Beam Source via Excited State Chemistry

TL;DR

This paper demonstrates that exciting Yb atoms to a metastable state in a cryogenic environment significantly enhances the brightness of a YbOH molecular beam, improving the sensitivity of experiments searching for physics beyond the Standard Model.

Contribution

It introduces a novel method of using excited state chemistry to boost the yield of cryogenic buffer gas beams of YbOH, with detailed experimental and quantum chemical analysis.

Findings

Enhanced YbOH beam brightness via excited Yb atoms.

Quantum calculations confirm increased reactivity and reaction pathways.

Potential for improved precision in BSM physics experiments.

Abstract

We use narrow-band laser excitation of Yb to substantially enhance the brightness of a cold beam of YbOH, a polyatomic molecule with high sensitivity to physics beyond the Standard Model (BSM). By exciting atomic Yb to the metastable $^3$P$_1$ state in a cryogenic environment, we significantly increase the chemical reaction cross-section for collisions of Yb with reactants. We characterize the dependence of the enhancement on the properties of the laser light, and study the final state distribution of the YbOH products. The resulting bright, cold YbOH beam can be used to increase the statistical sensitivity in searches for new physics utilizing YbOH, such as electron electric dipole moment (eEDM) and nuclear magnetic quadrupole moment (NMQM) experiments. We also perform new quantum chemical calculations that confirm the enhanced reactivity observed in our experiment. Additionally, our calculations compare reaction pathways of Yb($^3$P) with the reactants H$_2$O and H$_2$O$_2$. More generally, our work presents a broad approach for improving experiments that use cryogenic molecular beams for laser cooling and precision measurement searches of BSM physics.