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1. Effect of Fabry-Perot Cavities on Concentration Quenching

   S. Koutsares, S. Prayakarao (January 2019, Cleo)

   We show that concentration quenching of emission of dye molecules – an energy transfer to quenching centers – is inhibited in subwavelength Fabry-Perot cavities (or metal-insulator-metal, MIM, waveguides). 

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2. Förster resonance energy transfer in absorbing environment

   https://doi.org/10.1117/12.3027550  

   Petrosyan, Lyudvig S; Noginov, Mikhail A; Shahbazyan, Tigran V (October 2024, SPIE)

   Engheta, Nader; Noginov, Mikhail A; Zheludev, Nikolay I (Ed.)

   We present an analytical model for Förster resonance energy transfer between donors and acceptors in the presence of a metal surface. We find that energy transfer to the metal results in a reduction of the Förster radius, leading to a suppression of concentration quenching for high molecule concentrations. 

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3. Effect of Nonlocal Metal-Dielectric Environments on Concentration Quenching of HITC Dye

   https://doi.org/10.1364/CLEO_AT.2017.JTu5A.43  

   Prayakrao, Srujana; Bonner, Carl E.; Noginov, Mikhail A. (January 2017, CLEO: Science and Innovations 2017)

   We have experimentally demonstrated the inhibition of luminescence self-quenching in heavily doped HITC:PMMA polymeric films in vicinity of lamellar metal-dielectric metamaterials with hyperbolic dispersion and metallic surfaces. 

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4. A Turn-Off Fluorescent Sensor for Metal Ions Quantifies Corrosion in an Organic Solvent

   https://doi.org/10.1149/1945-7111/ad441f  

   Liu, Lianlian; Pfaffenberger, Zechariah; Siegel, Mark; Saini, Anuj; Kisley, Lydia (May 2024, Journal of The Electrochemical Society)

   We demonstrate that the corrosion of AISI 1045 medium carbon steel and pure aluminum can be quantified by the turn-off fluorescent sensor Phen Green-SK (PGSK) in ethanol-based solutions. We first evaluate the dependence of the chelation enhanced quenching of PGSK on iron and aluminum ion concentrations. Subsequently, we apply PGSK to examine the anodic dissolution of metal corrosion. The observed time-dependent PGSK-quenching quantifies the corrosion rates of two metals over 24 h of immersion in ethanol-based solutions. The PGSK-based quantification of corrosion is compared to scanning electron microscopy and electrochemical techniques, including open circuit potential and Tafel extrapolation. The corrosion rates calculated from PGSK-quenching and Tafel extrapolation are in agreement, and both indicate a decrease in corrosion rates over 24 h. Our work shows PGSK can efficiently sense and quantify anodic corrosion reactions at metal interfaces, especially in organic solvents or other non-aqueous environments where the application of electrochemical techniques can be limited by the poor conductivity of the surrounding medium. 

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5. 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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