Formation of ultracold RbCs molecules by photoassociation

TL;DR

This study demonstrates the formation of ultracold RbCs molecules via photoassociation in a magneto-optical trap, revealing short-range formation mechanisms and predicting molecules in deeply bound and ground states.

Contribution

It provides the first detailed analysis of short-range photoassociation of RbCs molecules using quantum chemistry calculations and experimental detection methods.

Findings

Molecules formed at short internuclear distances.

Deeply bound vibrational states are populated.

A significant fraction of molecules may be in the ground state.

Abstract

The formation of ultracold metastable RbCs molecules is observed in a double species magneto-optical trap through photoassociation below the ^85Rb(5S_1/2)+^133Cs(6P_3/2) dissociation limit followed by spontaneous emission. The molecules are detected by resonance enhanced two-photon ionization. Using accurate quantum chemistry calculations of the potential energy curves and transition dipole moment, we interpret the observed photoassociation process as occurring at short internuclear distance, in contrast with most previous cold atom photoassociation studies. The vibrational levels excited by photoassociation belong to the 5th 0^+ or the 4th 0^- electronic states correlated to the Rb(5P_1/2,3/2)+Cs(6S_1/2) dissociation limit. The computed vibrational distribution of the produced molecules shows that they are stabilized in deeply bound vibrational states of the lowest triplet state. We also predict that a noticeable fraction of molecules is produced in the lowest level of the electronic ground state.