Coherent coupling of molecular excitons to electronic polarizations of noble metal nanoparticles

We report the observation of coherent polarization coupling between the exciton of a molecular J-aggregate and the electronic polarization of noble metal nanoparticles. For Ag nanoparticles, coherent exciton coupling to the conduction band electrons leads to constructive interference and a long-lived exciton. For Au nanoparticles, the excitonic state interferes destructively with bound electron transition dipoles and the exciton lifetime is reduced by two orders of magnitude. Coherent polarization coupling in heterostructured nanomaterials may strongly impact the functionality of future nanoelectronic and nanooptical materials.