Exploring the Relationship between Plasmon Damping and Luminescence in Lithographically Prepared Gold Nanorods

In order to engineer plasmonic structures for specific applications, the energy decay pathways upon photon absorption must be understood. One of the decay pathways is the emission of light. In this work, we explore the effects of plasmon damping on the photonic density of states and resulting Purcell enhancement factor for gold nanorods and their relationship to the luminescence quantum yield. We compare the correlated scattering, photoluminescence, and quantum yield of different sizes of lithographically prepared nanorods. We recover a similar aspect ratio dependence for lithographically prepared nanorods as has been previously observed for colloidal rods. We change the damping experienced by the nanorods by removing the metal adhesion layer and compare to chemically synthesized nanorods of similar size. We also develop a gradual annealing method to decrease the damping experienced by our lithographically prepared nanorods by removing internal scattering defects. In all cases, we find a strong positive correlation between the degree of damping, expressed quantitatively through the resonance Quality Factor, and the luminescence quantum yield: as the Quality Factor increases the quantum yield follows in a roughly linear relationship. Simulations illustrate a corresponding increase in the photonic density of states as the Q-Factor increases.