20 September 2011 Theoretical modeling of relaxation dynamics in gold nanorod-dye assemblies for fluorescence enhancement
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Abstract
Using metal nanostructures to concentrate optical-frequency electric fields has garnered significant interest in the literature. For example, by combining an organic dye with a nanorod whose plasmon resonance frequency overalps the fluorescence maximum of the dye, a significant enhancement in the fluorescence quantum yield can be observed. The prevalent theory for describing such an enhancement is kinetic and ascribed to an increase in the intrinsic rate of fluorescence, while the rate of non-radiative decay remains constant. Analysis of the literature will reveal that systems exhibiting fluorescence enhancement also show an alteration of the Stokes shift. The traditional kinetic description of plasmon-enhanced fluorescence cannot explain the origin of this shift. Using the well-known theory developed by Onsager and Debye and applied to solvochromism, it will be shown that it is possible to model plasmon-enhanced fluorescence not as an increase in the intrinsic rate of fluorescence, but by a perturbation of the equilibrium, photoexcited dipole moment of an emitter coupled to a gold nanorod. This theory is different from the well-known Gersten-Nitzan model and offers an explanation of the altered Stokes shift in plasmon-enhanced fluorescence systems.
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Jarrett Vella, Jarrett Vella, Augustine Urbas, Augustine Urbas, } "Theoretical modeling of relaxation dynamics in gold nanorod-dye assemblies for fluorescence enhancement", Proc. SPIE 8096, Plasmonics: Metallic Nanostructures and Their Optical Properties IX, 80960A (20 September 2011); doi: 10.1117/12.892225; https://doi.org/10.1117/12.892225
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