# Many-molecule reaction triggered by a single photon in polaritonic chemistry

## TL;DR

This paper demonstrates theoretically that strong coupling of a molecular ensemble to a confined light mode can enable a single photon to trigger reactions in many molecules simultaneously, surpassing traditional photochemical limits.

## Contribution

It introduces the concept of a polaritonic supermolecule that allows collective molecular reactions triggered by a single photon, a novel approach in photochemistry.

## Key findings

- Single-photon many-molecule reactions are theoretically possible.
- Strong light-matter coupling creates hybrid states enabling collective reactions.
- Conditions for enhancing this effect are identified.

## Abstract

The second law of photochemistry states that in most cases, no more than one molecule is activated for an excited-state reaction for each photon absorbed by a collection of molecules. In this work, we demonstrate that it is possible to trigger a many-molecule reaction using only one photon by strongly coupling the molecular ensemble to a confined light mode. The collective nature of the resulting hybrid states of the system (the so-called polaritons) leads to the formation of a polaritonic "supermolecule" involving the degrees of freedom of all molecules, opening a reaction path on which all involved molecules undergo a chemical transformation. We theoretically investigate the system conditions for this effect to take place and be enhanced.