Self-Organized Plasmonic Metasurfaces: The Role of the Purcell Effect in Metal-Enhanced Chemiluminescence (MEC)

Chemiluminophores are entities, which exhibit wide-band light emission without any external light source, just caused by a chemical reaction. Since chemiluminescence usually yields to unfavorable competition with other channels of chemical energy dissipation, plasmonic nanoparticles can be employed to enhance the chemiluminescence quantum yield via acceleration of the radiative decay rate due to the Purcell effect. On the other hand, the catalytic action of metallic surface can contribute to the chemical reaction rate. Both mechanisms can lead to substantial chemiluminescence intensity enhancement when chemiluminophores are in contact with metal nanoparticles. Although the investigations devoted to MEC are numerous, the relative roles of the Purcell effect and catalysis in the chemiluminescence enhancement are still unclear. In this paper, with the use of a thin inert spacer layer deposited on top of a silver metasurface, we observe a moderate decrease of the chemiluminescence enhancement, which favors an electrodynamic mechanism. We also check that the continuous silver film without plasmon resonances causes no measurable chemiluminescence enhancement. As the results supported the electrodynamic mechanism of MEC, silver nanoparticles with suitable properties have been fabricated via physical vapor deposition on the substrate. We have theoretically optimized the silver nanoparticles shape and size distributions to tune their localized surface plasmon bands for the best overlap with the emission of luminol and some other chemiluminophores. Our design for plasmonic nanoparticles placed on the dielectric material may motivate a new generation of chemiluminescence-based devices for sensing applications.