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1. Light-Matter Interaction in Disordered Metal-Dielectric Environments

   S. Rout, M. Biener (January 2019, Cleo)

   We studied emission kinetics of HITC dye in disordered metal-dielectric environments and found that the latter, contrary to expectations, can reverse emission kinetics shortening in highly concentrated dyes, caused by a combination of relaxation processes. 

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2. Effect of metallic substrates and cavities on emission kinetics of dye-doped polymeric films

   https://doi.org/10.1364/JOSAB.409998  

   Koutsares, S.; Petrosyan, L_S; Prayakarao, S.; Courtwright, D.; Bonner, C_E; Shahbazyan, T_V; Noginov, M_A (December 2020, Journal of the Optical Society of America B)

   We have studied emission kinetics in dye-doped polymeric films (HITC:PMMA), deposited on top of glass and silver and embedded in Fabry–Perot cavities (metal-insulator-metal waveguides). For highly doped films on glass, we observed strong concentration quenching, as evidenced by a dramatic shortening of the emission kinetics, consistent with our previous studies. However, for the same dye-doped films on top of silver, slower emission kinetics were observed despite the high decay rates of individual dye molecules near the metallic surface. The concentration quenching rates in Fabry–Perot cavities were nearly identical to those of HITC:PMMA films deposited on top of silver. These findings are explained within a theoretical model for the inhibition of Förster energy transfer near a metallic surface. Furthermore, the emission kinetics of the dye-doped films on top of silver were approximately single exponential—consistent with the strong coupling of excited molecules with propagating surface plasmons. 

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3. Effect of Random Nanostructured Metallic Environments on Spontaneous Emission of HITC Dye

   https://doi.org/10.3390/nano10112135  

   Rout, Sangeeta; Qi, Zhen; Petrosyan, Ludvig S.; Shahbazyan, Tigran V.; Biener, Monika M.; Bonner, Carl E.; Noginov, Mikhail A. (November 2020, Nanomaterials)

   null (Ed.)

   We have studied emission kinetics of HITC laser dye on top of glass, smooth Au films, and randomly structured porous Au nanofoams. The observed concentration quenching of luminescence of highly concentrated dye on top of glass (energy transfer to acceptors) and the inhibition of the concentration quenching in vicinity of smooth Au films were in accord with our recent findings. Intriguingly, the emission kinetics recorded in different local spots of the Au nanofoam samples had a spread of the decay rates, which was large at low dye concentrations and became narrower with increase of the dye concentration. We infer that in different subvolumes of Au nanofoams, HITC molecules are coupled to the nanofoams weaker or stronger. The inhibition of the concentration quenching in Au nanofoams was stronger than on top of smooth Au films. This was true for all weakly and strongly coupled subvolumes contributing to the spread of the emission kinetics. The experimental observations were explained using theoretical model accounting for change in the Förster radius caused by the strong energy transfer to metal. 

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4. Energy transfer chemiluminescence for ratiometric pH imaging

   https://doi.org/10.1039/C8OB00972D  

   An, Weiwei; Mason, Ralph P.; Lippert, Alexander R. (January 2018, Organic & Biomolecular Chemistry)

   Chemiluminescence imaging offers a low background and high sensitivity approach to imaging analytes in living cells and animals. Intensity-based measurements have been developed, but require careful consideration of kinetics, probe localization, and fluctuations in quantum yield, all of which complicate quantification. Here, we report a ratiometric strategy for quantitative chemiluminescence imaging of pH. The strategy relies on an energy transfer cascade of chemiluminescence emission from a spiroadamantane 1,2-dioxetane to a ratiometric pH indicator via fluorescent dyes in Enhancer solutions. Monitoring the pH-dependent changes in chemiluminescence emission at multiple wavelengths enables ratiometric imaging and quantification of pH independent from variations due to kinetics and probe concentration. 

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5. Control of Concentration Quenching with Metallic Substrates and Cavities

   Koutsares, Samantha R; Petrosyan, Ludvig S; Courtwright, Devon; Prayakarao, Srujana; Bonner, Carl E; Shahbazyan, Tigran V; Noginov, Mikhail A. (January 2020, Conference on Lasers and Electrooptics)

   We found that inhibition of concentration quenching of HITC dye in Fabry-Perot cavities is almost similar to that on top of silver. Low convexity of the emission kinetics suggests strong coupling mediated by surface plasmons. 

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