Photoisomerization is a chemical process in which the nuclear structure of a molecule is modified after absorption of a photon. It is of great importance to many fundamental processes in nature such as photosynthesis and human vision, and has many technological applications such as in optical switches and solar energy storage. In conventional photochemistry, the behavior of these reactions is ruled by the Stark-Einstein law: only one molecule undergoes a reaction per absorbed photon (although there are known exceptions).
We just published a paper in Physical Review Letters on inducing a Many-Molecule Reaction Triggered by a Single Photon in Polaritonic Chemistry. In this work, we have shown the possibility of overcoming the Stark-Einstein law by taking advantage of the quantum electrodynamic phenomenon of light-matter strong coupling. In this regime, the system excitations, called polaritons, have mixed light-matter character and inherit properties from both their constituents. This can lead to modifications of both the material and chemical properties of the system. By taking advantage of this new “polaritonic chemistry”, it is possible to open new reaction pathways that are otherwise forbidden in conventional chemistry. We considered organic molecules proposed for solar energy storage, and demonstrated that it is possible that polaritonic chemistry can be used to manipulate the potential energy surfaces that determine chemical reactions in such a way that absorbing a photon causes one molecule to react after another, inducing a stepwise chain reaction involving many molecules.
This work is another example of the potential of polaritonic chemistry, of great interest for both fundamental and applied reasons. In particular, it is noteworthy how this developing field brings together chemistry and quantum electrodynamics. While in standard chemical reactions, light and molecules are separated and have distinct roles, polaritonic chemistry calls for a redefinition of the molecule, and enables novel and exotic chemical processes, even finding ways to defy the well-established laws of conventional photochemistry.
The paper has been highlighted by the editors as an Editors’ Suggestion, and an accompanying Viewpoint article has been published in Physics.
Update 2017-10-03: The article has also been featured as a Research Highlight in Nature.