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Excimer based FRET between non-FRET pair flourophores aided by the aromatic moiety of anionic surfactants: An experimental observation
摘要： A new FRET pair has been reported based on the apperance of excimeric emission and hence significant spectral overlap between an otherwise non-FRET pair fluorophores viz pyrene and rhodamine 6G in the anionic sodiumdodecylbenzenesulfonate (SDBS) micellar system. The occurence of FRET based on such modulation of spectral overlap integral has not been dealt with in detail in comparison to the other FRET parameters like distance between the fluorophores and orientation. Due to the presence of benzene ring in the SDBS micellar system the formation of excimers is augemented due to the π?π interactions between the pyrene molecules and the benzene units of the surfactants. The excimeric pyrene has a bathochromically shifted peak which overlaps with the absorption peak of rhodamine 6G thereby giving rise to energy transfer as FRET between these otherwise non-FRET pair molecules. The efficiency of FRET between the pyrene and rhodamine 6G can be modulated by the degree of spectral overlap between the excimeric peak of pyrene and the absorption peak of rhodamime6g. All the experiments were carried in the Sodiumdodecylsulfate (SDS) micellar system also, which unlike SDBS does not possess any benzene unit, in order to compare the results of excimer formation as well the FRET process.
关键词： rhodamine 6G,Pyrene,overlap integral,Excimer,FRET
更新于2025-11-19 16:46:39
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Optical Characterization of Doped Thermoplastic and Thermosetting Polymer-Optical-Fibers
摘要： The emission properties of a graded-index thermoplastic polymer optical fiber and a step-index thermosetting one, both doped with rhodamine 6G, have been studied. The work includes a detailed analysis of the amplified spontaneous emission together with a study of the optical gains and losses of the fibers. The photostability of the emission of both types of fibers has also been investigated. Comparisons between the results of both doped polymer optical fibers are presented and discussed.
关键词： polymer optical fibers,thermoplastic fibers,rhodamine 6G,light-emitting polymers,optical gain,amplified spontaneous emission,thermosetting fibers
更新于2025-11-14 15:30:11
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Silver Nanostructures on Graphene Oxide as the Substrate for Surface-Enhanced Raman Scattering (SERS)
摘要： Nanosized surface-enhanced Raman scattering (SERS) substrates fabricated by the controlled growth of metal nanostructures on water-dispersed two-dimensional nanomaterials can open a new avenue for SERS analysis of liquid samples in biological fields. In this work, regular and uniform Ag nanostructures were grown on the surface of graphene oxide (GO) through a microwave-assisted hydrothermal method. Polyamidoamine (PAMAM) dendrimers were assembled on the surface of GO to form GO/PAMAM templates for growing Ag nanostructures, which are primarily comprised of Ag dimers and trimers. The prepared Ag/GO nanocomposites are highly dispersed and stable in aqueous solution and may be used as substrates for enhanced Raman detection of rhodamine 6 G (R6G) in aqueous solution. This special substrate provides high-performance SERS and suppresses R6G fluorescence in aqueous solution and is promising as a nanosized material for the enhanced Raman detection of liquid samples in biological diagnostics.
关键词： graphene oxide (GO),Surface-enhanced Raman scattering (SERS),polyamidoamine (PAMAM) dendrimers,transmission electron microscopy (TEM),Fourier transform infrared (FTIR) spectroscopy,rhodamine 6G (R6G)
更新于2025-09-23 15:23:52
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Controlled dye release from a metala??organic framework: a new luminescent sensor for water
摘要： By introducing the dye Rhodamine 6G (R6G) into a metal–organic framework (MOF), Mn-sdc-2 (H2sdc ? 4,40-stilbenedicarboxylic acid), with a pore size of 20 (cid:2) 9.8 (cid:1)A2, the composite R6G@Mn-sdc-2 was obtained. Subsequently, the MOF Mn-sdc-1 with a smaller pore size of 7.5 (cid:2) 7.5 (cid:1)A2 can be formed through a single-crystal to single-crystal transformation from Mn-sdc-2, thus tightly locking the dye R6G within the pores. Compared with R6G@Mn-sdc-2, R6G@Mn-sdc-1 exhibits a stronger ?uorescence emission of R6G. Because the MOF Mn-sdc-1 can reversibly transform back to Mn-sdc-2 in the presence of trace water, the dye R6G can be released. This enables R6G@Mn-sdc-1 to be used as a new luminescent sensor for trace water in organic solvents by monitoring the ?uorescence intensity of released R6G. The limit of detection can reach 0.035% in ethanol (v : v), which is among the most sensitive ?uorescent water probes.
关键词： fluorescence,metal–organic framework,luminescent sensor,water detection,Rhodamine 6G
更新于2025-09-23 15:19:57
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Coupling of the First and Second Excited States of R6G Dye with the Fabry-Perot Cavity
摘要： Coupling of macroscopic ensembles of highly concentrated R6G molecules with aluminum and silver Fabry–Perot cavities of different sizes, in which one or two standing wave modes are in resonance with the absorption transition(s) of the dye molecules, have been studied. (i) It has been found that strong coupling of the cavity with one molecular eigenstate (S0!S1 transition) does not perturb the energies of the other molecular states. (ii) The S0!S2 absorption transition is too weak to strongly couple to the resonant cavity (“λ” standing wave mode). However, the resonant cavity causes a blue shift of the S0!S2 excitation band. (iii) The splitting of the dispersion curve is theoretically predicted and experimentally observed at strong coupling of the cavity resonance (“λ” standing wave mode) with the material resonances of Ag, including bound electron and “epsilon equal zero” transitions.
关键词： spectroscopy,Fabry–Perot cavity,energy splitting,excited states,spectral shifts,rhodamine 6G dye,strong coupling
更新于2025-09-19 17:15:36
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Study of optical and electrical property of NaI-doped PPy thin film with excellent photocatalytic property at visible light
摘要： Conductive polymers perform as a new class of very active photocatalysts under visible light. Among them, polypyrrole (PPy) is one of the most promising conjugated polymers with a wide range of applications. PPy and doped PPy were synthesized on glass plate in thin film form by a facile simple successive ionic layer adsorption and reaction method. Polypyrrole is doped with dodecyl benzene sulphonic acid, toluene sulphonic acid, hydrochloric acid, sodium iodide (NaI), citric acid (commercial) and citric acid (lemon). The synthesized thin film was well characterized using UV–visible spectrophotometer, scanning electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis and photoluminescence (PL). The electrical conductivity was measured by Hall effect measurements. Among various organic and inorganic acid dopants, NaI-doped PPy thin film exhibited narrow band gap and has excellent ability to absorb light in red region of the spectrum. NaI-doped PPy thin film showed higher conductivity when compared to other dopants. A lower PL intensity of NaI-PPy thin film indicates higher electron–hole pair separation efficiency. The photocatalytic activities of PPy thin film and NaI-doped PPy thin film on rhodamine 6G dye under visible light were systematically investigated. NaI-doped PPy thin film had better degradation efficiency than PPy due to its higher electron–hole pair separation efficiency.
关键词： Dye degradation,Polypyrrole,Rhodamine 6G,Thin film
更新于2025-09-19 17:15:36
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Random Laser Action from Electrospun Polymeric Nanofibers Doped Either with Organic Dye or Semiconductor Nanoprisms
摘要： The search for light sources with targeted characteristics motivates the work of a large part of the photonics community. One topical subject in this area is the study of Random Lasers (RLs), which use as feedback mechanism the light scattering in a random medium instead of a Fabry-Perot cavity. A large variety of RLs and a diversity of applications have already been demonstrated. Of interest in many applications are RLs based on flexible hosts, which act not only as mechanical support, but also as scattering agent. Such host can be obtained, for example, by electrospinning fibers made by environment-friendly materials. In this work, we report on a technique to produce a system composed by electrospun acetate ester of cellulose nanofibers (AEC-NFs) containing poly(ethylene oxide) – PEO (10% or 20% wt. - known to improve the mechanical properties of AEC-NFs), which presence originates a double-peaked diameter distribution centred around 120 nm and 600 nm. RL experiments were made with either Rhodamine 6G (Rh6G, 2 mM) or 40% wt. ZnO nanoprisms (NPs), that act as gain media. By varying the PEO amount in the AEC-NFs we investigate how the structures with smaller diameters act as scatterers for obtaining RL emission. Raman spectroscopy was performed in order to assure that PEO has been incorporated to the AEC-NFs in the desired amount.
关键词： poly(ethylene oxide),Rhodamine 6G,Random Lasers,ZnO nanoprisms,electrospun nanofibers
更新于2025-09-11 14:15:04
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Reusable surface-enhanced Raman substrates using microwave annealing
摘要： In this work, we report the fabrication of large-scale homogeneous surface-enhanced Raman scattering (SERS) substrates using a microwave annealing (MWA) process on Ag thin films on silicon, using a typical low-cost domestic microwave oven, avoiding the use of chemicals and stabilizing agents, or time-consuming and expensive approaches. We provide evidence that in 5–15 s, uniform and reproducible SERS substrates of several centimeter squares can be grown, providing a Raman signal enhancement of five orders of magnitude, for an incident Raman laser with an intensity as low as ~ 0.035 mW, against the characterization of Rhodamine 6G, which is a standard test molecule for SERS. Moreover, we tested the reusability of the fabricated MWA SERS substrates under conditions as tough as ultrasonic sonication in isopropyl alcohol and acetone for 15 min, respectively, and we demonstrate that our SERS substrates can be efficiently reused for more than six times after sonication, which is quite critical since it minimizes the cost of the procedure to minimum.
关键词： Surface-enhanced Raman scattering (SERS),Ag thin films,Rhodamine 6G (R6G),Reusable substrates,Microwave annealing (MWA)
更新于2025-09-10 09:29:36
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Enhanced visible-light-driven photocatalysis of Bi2YO4Cl heterostructures functionallized by bimetallic RhNi nanoparticles
摘要： Bismuth-based Sillen-Aurivillius compounds are being explored as efficient photocatalyst materials for the degradation of organic pollutants due to their unique layered structure that favours effective separation of electron-hole pairs. In this work, we synthesized Sillen-Aurivillius-related Bi2YO4Cl with the bandgap of 2.5 eV by a simple solid-state reaction and sensitized with rhodium nickel (RhNi) nanoparticles (NPs) to form the RhNi/Bi2YO4Cl heterostructure. Photocatalytic activities of BiOCl, Bi2YO4Cl and the RhNi/Bi2YO4Cl heterostructure were examined for the degradation of rhodamine-6G under visible-light illumination. Results demonstrated that the photocatalytic dye degradation efficiency of RhNi/Bi2YO4Cl heterostructures is higher than those of BiOCl and Bi2YO4Cl, attributed to the synergistic molecular-scale alloying effect of bimetallic RhNi NPs. The plausible mechanism for the degradation of rhodamine-6G and the effective electron-hole pair utilization mechanism were discussed.
关键词： Bi2YO4Cl,RhNi catalyst,rhodamine-6G,photocatalysis,BiOCl
更新于2025-09-04 15:30:14
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Ag nanoparticle decorated MnO <sub/>2</sub> flakes as flexible SERS substrates for rhodamine 6G detection
摘要： Smart design of advanced substrates for surface-enhanced Raman scattering (SERS) activity is challenging but vital. Herein, we synthesized a new kind of AgNPs/MnO2@Al flexible substrate as a SERS substrate for the detection of the analyte rhodamine 6G (R6G). The fabrication of porous MnO2 nanoflakes on Al foil was conducted via a facile hydrothermal strategy. Owing to the large active surface area of the MnO2 nanoflakes, the Ag nanoparticles were immobilized and displayed superior SERS performance with a low detection concentration of 1 × 10?6 M for R6G. In addition, the SERS performance was found to be strongly related to the morphology of the MnO2@Al substrate material. Our smart design may provide a new method of construction for other advanced SERS substrates for the detection of R6G.
关键词： Ag nanoparticles,rhodamine 6G detection,MnO2 flakes,flexible SERS substrates
更新于2025-09-04 15:30:14