Control of Optical Transitions with Magnetic Fields in Weakly Bound Molecules

TL;DR

This paper demonstrates how magnetic fields can be used to precisely control optical transition strengths in weakly bound diatomic molecules, enabling advances in molecular spectroscopy and potential applications in molecular clocks.

Contribution

It introduces a method to tune forbidden optical transitions over five orders of magnitude using magnetic fields, supported by simple models and quantum chemistry calculations.

Findings

Achieved tunability of optical transition strengths over 5 orders of magnitude.

Observed previously inaccessible $f$-parity excited states.

Showed how mixed quantization simplifies molecular spectroscopy.

Abstract

In weakly bound diatomic molecules, energy levels are closely spaced and thus more susceptible to mixing by magnetic fields than in the constituent atoms. We use this effect to control the strengths of forbidden optical transitions in $^{88}$Sr$_2$ over 5 orders of magnitude with modest fields by taking advantage of the intercombination-line threshold. The physics behind this remarkable tunability is accurately explained with both a simple model and quantum chemistry calculations, and suggests new possibilities for molecular clocks. We show how mixed quantization in an optical lattice can simplify molecular spectroscopy. Furthermore, our observation of formerly inaccessible $f$-parity excited states offers an avenue for improving theoretical models of divalent-atom dimers.