Femtosecond Photophysics of Molecular Polaritons

TL;DR

This paper reviews the ultrafast photophysical behavior of molecular polaritons, emphasizing how strong light-molecule interactions influence energy transfer and molecular properties, with a focus on pump-probe spectroscopy insights.

Contribution

It highlights the importance of collective effects and ultrafast spectroscopy in understanding energy dynamics in strongly coupled molecular systems, proposing new approaches for polariton chemistry.

Findings

Ultrafast pump-probe spectroscopy reveals energy transfer pathways in polaritons.

Analyzing free energy structures offers new insights into energy flow.

Strong coupling can modify molecular properties and reactions.

Abstract

Molecular polaritons are hybrid states of photonic and molecular character that form when molecules strongly interact with light. Strong coupling tunes energy levels and importantly, can modify molecular properties (e.g. photoreaction rates) opening an avenue for novel polariton chemistry. In this perspective, we focus on the collective aspects of strongly coupled molecular systems and how this pertains to the dynamical response of such systems, which though of key importance for attaining modified function under polariton formation, is still not well understood. We discuss how the ultrafast time and spectral resolution make pump-probe spectroscopy an ideal tool to reveal the energy transfer pathways from polariton states to other molecular states of functional interest. Finally, we illustrate how analyzing the free (rather than electronic) energy structure in molecular polariton systems may provide new clues into how energy flows and thus how strong coupling may be exploited.