Electronic Strong Coupling of Gas-Phase Molecular Iodine

TL;DR

This paper reports the first demonstration of electronic strong coupling in a gas-phase molecular iodine system, creating molecular polaritons in a pristine environment, which advances understanding and control of light-matter interactions in gases.

Contribution

It introduces the first realization of electronic polaritons in a molecular gas, enabling new studies in polariton photochemistry and photophysics in a solvent-free environment.

Findings

Achieved electronic strong coupling of gas-phase iodine transitions near 532.2 nm.

Controlled coupling strengths and detuning via molecular density and cavity length.

First demonstration of molecular polaritons in a gas-phase environment.

Abstract

Molecular polaritons, hybrid light-matter states formed from the strong coupling of molecular transitions and discrete photonic modes, are a compelling platform for optical control of chemical reactivity. Despite the origins of the field of polaritonics in atomic gases, strong coupling of molecular gases remains underexplored. The pristine, solvent-free gas-phase environment may prove ideal for gaining mechanistic understanding of molecular behavior under strong light-matter coupling. In this work, we achieve electronic strong coupling of the B-X, $\nu_1$ = 0$\rightarrow$32, J = 53$\rightarrow$52 and B-X, $\nu_1$ = 0$\rightarrow$34, J = 103$\rightarrow$102 rovibronic transitions of gas-phase iodine (I$_2$) lying near 532.2 nm. We access a range of coupling strengths and detuning conditions with fine control over molecular number density and cavity length stabilization. This effort represents the first demonstration of electronic polaritons in a molecular gas and opens a new platform for polariton photochemistry and photophysics.