Vibronic branching ratios for nearly-closed rapid photon cycling of SrOH

TL;DR

This paper measures vibrational branching ratios in SrOH with high precision, enabling effective laser cooling schemes, and supports the findings with ab initio calculations that match experimental results.

Contribution

It provides the first precise experimental determination of SrOH vibrational branching ratios and combines them with ab initio calculations to facilitate laser cooling applications.

Findings

Small branching ratios enable >10^4 photon scatters per molecule.

Ab initio calculations agree well with experimental data.

Results support practical laser cooling of SrOH.

Abstract

The vibrational branching ratios of SrOH for radiative decay to the ground electronic state, $X^{2}\Sigma^{+}$, from the first two electronically excited states, $A^{2}\Pi$ and $B^{2}\Sigma^{+}$, are determined experimentally at the $\sim10^{-5}$ level. The observed small branching ratios enable the design of a full, practical laser-cooling scheme, including magneto-optical trapping and sub-Doppler laser cooling, with $>10^4$ photon scatters per molecule. Ab initio calculations sensitive to weak vibronic transitions are performed to facilitate the experimental measurement and analysis, and show good agreement with experiment.