Laser spectroscopy of aromatic molecules with optical cycling centers: strontium (I) phenoxides

TL;DR

This study demonstrates the potential of strontium phenoxides for laser cooling by achieving high optical cycling closure and providing detailed spectroscopic data to guide future quantum control applications.

Contribution

The paper reports the first spectroscopic characterization of SrOPh and variants, confirming their suitability for laser cooling and identifying candidate transitions for quantum experiments.

Findings

High optical cycling closure achieved experimentally

Spectroscopic constants estimated for SrOPh

Candidate optical cycling transitions identified

Abstract

We report the production and spectroscopic characterization of strontium (I) phenoxide ($\mathrm{SrOC}_6\mathrm{H}_5$, or SrOPh) and variants featuring electron-withdrawing groups designed to suppress vibrational excitation during spontaneous emission from the electronically excited state. Optical cycling closure of these species, which is the decoupling of vibrational state changes from spontaneous optical decay, is found by dispersed laser-induced fluorescence spectroscopy to be high, in accordance with theoretical predictions. A high-resolution, rotationally-resolved laser excitation spectrum is recorded for SrOPh, allowing the estimation of spectroscopic constants and identification of candidate optical cycling transitions for future work. The results confirm the promise of strontium phenoxides for laser cooling and quantum state detection at the single-molecule level.