Rovibrational Polaritons in Gas-Phase Methane

TL;DR

This paper introduces a new experimental platform for studying rovibrational polaritons in gas-phase methane, enabling exploration of vibrational strong coupling effects in isolated molecular systems.

Contribution

It establishes a cryogenic buffer gas cell setup for achieving vibrational strong coupling in gas-phase molecules, demonstrated with methane, and provides a basis for cavity-controlled chemistry studies.

Findings

Achieved strong coupling with methane's rovibrational transitions

Reproduced results with classical cavity transmission simulations

Provided a new testbed for cavity-altered chemical processes

Abstract

Polaritonic states arise when a bright optical transition of a molecular ensemble is resonantly matched to an optical cavity mode frequency. Here, we lay the groundwork to study the behavior of polaritons in clean, isolated systems by establishing a new platform for vibrational strong coupling in gas-phase molecules. We access the strong coupling regime in an intracavity cryogenic buffer gas cell optimized for the preparation of simultaneously cold and dense ensembles, and report a proof-of-principle demonstration in gas-phase methane. We strongly cavity-couple individual rovibrational transitions and probe a range of coupling strengths and detunings. We reproduce our findings with classical cavity transmission simulations in the presence of strong intracavity absorbers. This infrastructure provides a new testbed for benchmark studies of cavity-altered chemistry.