High resolution photoassociation spectroscopy of the excited $c^3\Sigma_{1}^+$ potential of $^{23}$Na$^{133}$Cs

TL;DR

This study conducts high-resolution photoassociation spectroscopy on the excited $c^3\Sigma_{1}^+$ potential of NaCs molecules, identifying vibrational and hyperfine structures, and demonstrates two-photon transfer to the ground state.

Contribution

It provides detailed spectroscopic data of the $c^3\Sigma_{1}^+$ potential and explores the use of a specific vibrational line for molecular state transfer.

Findings

Identified eleven vibrational lines with hyperfine structure.

Observed unexpected broadening linked to spin-orbit coupling.

Demonstrated two-photon transfer to the molecular ground state.

Abstract

We report on photoassociation spectroscopy probing the $c^3\Sigma_{1}^+$ potential of the bi-alkali NaCs molecule, identifying eleven vibrational lines between $v' = 0$ and $v' = 25$ of the excited $c^3\Sigma_{1}^+$ potential, and resolving their rotational and hyperfine structure. The observed lines are assigned by fitting to an effective Hamiltonian model of the excited state structure with rotational and hyperfine constants as free parameters. We discuss unexpected broadening of select vibrational lines, and its possible link to strong spin-orbit coupling of the $c^3\Sigma_{1}^+$ potential with the nearby $b^3\Pi_1$ and $B^1\Pi_1$ manifolds. Finally we report use of the $v' = 22$ line as an intermediate state for two-photon transfer of weakly bound Feshbach molecules to the rovibrational ground state of the $X^1\Sigma^+$ manifold.