The role of electronic excitation in cold atom-ion chemistry

TL;DR

This study investigates how electronic excitation affects charge exchange reactions in ultracold Ca atoms and Ba$^+$ ions, revealing that ion excitation significantly influences reaction rates and that proper atom-ion pairing can reduce unwanted reactions.

Contribution

It provides experimental insights into the role of electronic excitation in ultracold atom-ion chemistry and demonstrates how to mitigate undesired reactions through pair selection.

Findings

Ion electronic excitation critically influences reaction rates.

Atomic excitation has a lesser effect on reactions.

Proper atom-ion pairing can suppress unwanted chemical reactions.

Abstract

The role of electronic excitation in charge exchange chemical reactions between ultracold Ca atoms and Ba$^+$ ions, confined in a hybrid trap, is studied. This prototypical system is energetically precluded from reacting in its ground state, allowing a particularly simple interpretation of the influence of electronic excitation. It is found that while electronic excitation of the ion can critically influence the chemical reaction rate, electronic excitation of the neutral atom is less important. It is also experimentally demonstrated that with the correct choice of the atom-ion pair, it is possible to mitigate the unwanted effects of these chemical reactions in ultracold atom-ion environments, marking an important step towards the next generation of hybrid devices.