Sensitive Detection of Cold Cesium Molecules by Radiative Feshbach Spectroscopy

TL;DR

This paper introduces a highly sensitive spectroscopic method to detect cold cesium molecules formed near Feshbach resonances, revealing detailed molecular states and dynamics with unprecedented sensitivity.

Contribution

The study demonstrates a radiative Feshbach spectroscopy technique that surpasses previous methods in sensitivity, enabling detection of weakly-coupled molecular states and providing a model for atom-molecule interactions.

Findings

Detected over 20 molecular states near Feshbach resonances

Achieved 300 times greater sensitivity than previous methods

Estimated coexistence of over 2×10^5 Cs2 molecules with 10^8 Cs atoms

Abstract

We observe the dynamic formation of $Cs_2$ molecules near Feshbach resonances in a cold sample of atomic cesium using an external probe beam. This method is 300 times more sensitive than previous atomic collision rate methods, and allows us to detect more than 20 weakly-coupled molecular states, with collisional formation cross sections as small as $\sigma =3\times 10^{-16}$cm$^2$. We propose a model to describe the atom-molecule coupling, and estimate that more than $2 \times 10^5$ $Cs_2$ molecules coexist in dynamical equilibrium with $10^8$ $Cs$ atoms in our trap for several seconds.