Photodissociation of trapped Rb$^+_2$ : Implications for simultaneous trapping of atoms and molecular ions

TL;DR

This study investigates how cooling light in a rubidium MOT causes photodissociation of trapped Rb$_2^+$ ions, combining experimental measurements with theoretical calculations to understand the process's universality for alkali diatomic ions.

Contribution

It provides the first combined experimental and theoretical analysis of Rb$_2^+$ photodissociation under MOT conditions, highlighting the universal impact of cooling light on alkali diatomic molecular ions.

Findings

Measured decay rates match theoretical predictions.

Photodissociation is caused by MOT cooling light.

The process is likely universal for similar ions.

Abstract

The direct photodissociation of trapped $^{85}$Rb$_2^+$ (rubidium) molecular ions by the cooling light for the $^{85}$Rb magneto-optical trap (MOT) is studied, both experimentally and theoretically. Vibrationally excited Rb$_{2}^{+}$ ions are created by photoionization of Rb$_{2}$ molecules formed photoassociatively in the Rb MOT and are trapped in a modified spherical Paul trap. The decay rate of the trapped Rb$_{2}^{+}$ ion signal in the presence of the MOT cooling light is measured and agreement with our calculated rates for molecular ion photodissociation is observed. The photodissociation mechanism due to the MOT light is expected to be active and therefore universal for all homonuclear diatomic alkali metal molecular ions.