Comparative analysis of simulation results for metal-enhanced fluorescence of fluorophore molecules using 0D and 3D approximations
Alexander N. Yakunin1, Sergey V. Zarkov1, Yuri A. Avetisyan1, Garif G. Akchurin1,2, Valery V. Tuchin1,2,3; 1Institute of Precision Mechanics and Control, Federal Research Centre “Saratov Scientific Centre of the Russian Academy of Sciences”, Saratov, Russia; 2Department of Optics and Biophotonics and Science Medical Center, Saratov State University, Saratov, Russia; 3Laboratory of Laser Molecular Imaging and Machine Learning, Tomsk State University, Tomsk, Russia
Abstract
A new 3D electrodynamic model is proposed for analyzing metal-enhanced fluorescence in a complex (consisting of a fluorophore molecule located near a plasmonic nanoparticle); unlike the traditional point-dipole approximation, this model accounts for the fluorophore molecule's shape, finite size, and optical properties. A numerical study of the TagRFP plasmonic-fluorophore complex demonstrates that the proposed model significantly refines parameter values for optimal fluorescence conditions—specifically, achieving the maximum fluorescence enhancement factor, Kflu. An advantage of the 3D model is its ability to capture the physical mechanism behind the nonlinear coupling between the distributed emission source and the nanoparticles; this is reflected in the significant impact of nanoparticle size on the nanocomplex's quantum yield—an effect that 0D modeling fails to describe. It is also shown that, consequently, for small gaps D (1–7 nm) between the fluorophore molecule and a gold or silver nanoparticle, the 0D model tends to overestimate the optical field intensity enhancement factor Ksi (by up to 2.7 times in the cases studied at minimum D) and underestimate the quantum yield Y (by up to 50 times) compared to 3D model calculations. Thus, the discrepancy in determining Kflu arises from the interplay of these two trends and reaches a factor of 12. As the fluorophore's intrinsic quantum yield Y0 decreases, the degree of correction to Kflu provided by the 3D model increases.
Speaker
Yakunin Alexander N.
Institute of Precision Mechanics and Control, Federal Research Centre “Saratov Scientific Centre of the Russian Academy of Sciences”, Saratov, Russia
Russia
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