Untangling energy dependent radiation damping and chemical interface damping in gold nanorods
Plasmonic metal nanostructures have long been investigated for their use in light harvesting and sensing applications. It may be more favorable to enhance either radiative or non-radiative effects that arise after plasmon decay depending on the intended application. Therefore, understanding the mechanisms and design space of plasmon decay is of great importance for practical applications. Specifically, radiation damping and chemical interface damping are crucial in plasmonic sensing and plasmon-enhanced optoelectronics. However, in systems where it is desirable to study both radiation and chemical interface damping, these terms can become entangled due to large energy shifts induced by metal oxide coatings that provide acceptor states for interfacial charge transfer. Additionally, the size of plasmonic nanoparticles plays a critical role in altering the contribution ratio of radiation damping and chemical interface damping to the total plasmon damping. To address this, we employed single-particle dark field scattering to systematically study the plasmon linewidth of gold nanorods. By coating gold nanorods with an insulating material, we can isolate radiation damping contributions and fully account for energy-dependent radiation damping with a simple analytical model. We apply this analysis to metal-semiconductor nanoparticle interfaces where charge transfer can occur over a Schottky barrier for three sizes of gold nanorods. In this way, we are able to calculate charge transfer efficiencies of up to 34% while fully accounting for other damping terms.
Plasmonics, Chemical interface damping, Radiation damping
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