Upper Bound to the Ionization Energy of 85Rb2

TL;DR

This study establishes an upper limit for the ionization energy of 85Rb2 molecules using ultracold atom photoassociation and autoionization measurements, providing key insights into molecular ionization thresholds.

Contribution

The paper introduces a novel method to bound the ionization energy of 85Rb2 by observing autoionization of excited molecular states below the atomic limit.

Findings

Upper bound to ionization energy: 31348.0(6) cm-1

Lower bound to dissociation energy of 85Rb2+: 6307.5(6) cm-1

Autoionization onset observed below the 5s+7p atomic limit

Abstract

We report an upper bound to the ionization energy of 85Rb2 of 31348.0(6) cm-1, which also provides a lower bound to the dissociation energy D0 of 85Rb2+ of 6307.5(6) cm-1. These bounds were measured by the onset of autoionization of excited states of 85Rb2 below the 5s+7p atomic limit. We form 85Rb2 molecules via photoassociation of ultracold 85Rb atoms, and subsequently excite the molecules by single-photon ultraviolet transitions to states above the ionization threshold.