Giant Helium Dimers Produced by Photoassociation of Ultracold Metastable Atoms

TL;DR

This paper reports the production and spectroscopic analysis of giant helium dimers formed via photoassociation in ultracold metastable helium atoms, revealing five long-range bound states with large classical turning points.

Contribution

It provides the first experimental observation and theoretical confirmation of five long-range bound states in helium dimers, expanding understanding of ultracold molecular physics.

Findings

Good agreement between measurements and calculations of bound states.

Identification of states with large classical inner and outer turning points.

Observation of strong heating effects at molecular resonances.

Abstract

We produce giant helium dimers by photoassociation of metastable helium atoms in a magnetically trapped, ultracold cloud. The photoassociation laser is detuned red of the atomic $2^3S_1 - 2^3P_0 $ line and produces strong heating of the sample when resonant with molecular bound states. The temperature of the cloud serves as an indicator of the molecular spectrum. We report good agreement between our spectroscopic measurements and our calculations of the five bound states belonging to a $0_u^+$ purely long-range potential well. These previously unobserved states have classical inner turning points of about 150 $a_0$ and outer turning points as large as 1150 $a_0$.