Stability of rubidium molecules in the lowest triplet state

TL;DR

This paper investigates the lifetime of rubidium molecules in the lowest triplet state, revealing a decay mechanism that results in a surprisingly long lifetime of about 21 minutes, important for ultracold molecule experiments.

Contribution

It identifies and analyzes the radiative decay mechanism affecting rubidium molecules in the lowest triplet state, providing a detailed estimate of their lifetime.

Findings

Lifetime of rubidium molecules in the triplet state is approximately 21 minutes.

Decay occurs via radiative mechanism involving interatomic spin-orbit interaction.

The triplet state is relatively stable compared to other excited molecular states.

Abstract

Experiments involving ultracold molecules require sufficiently long lifetimes, which can be very short for excited rovibrational states in the molecular potentials. For alkali atoms such as rubidium, a lowest rovibrational molecular state can both be found in the electronic singlet and triplet configurations. The molecular singlet ground state is absolutely stable. However, the lowest triplet state can decay to a deeper bound singlet molecule due to a radiative decay mechanism that involves the interatomic spin-orbit interaction. We investigate this mechanism, and find the lifetime of rubidium molecules in the lowest triplet rovibrational state to be about 21 minutes.