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Resonant energy transfer and light scattering enhancement of plasmonic random lasers embedded with silver nanoplates
摘要： The resonant energy transfer enhancement from a plasmonic random laser (PRL) has been investigated by means of a dye-covered PVA film with embedded silver nanoplates (DC-PVA/AgNPs). Different sizes and morphologies of AgNPs were adopted to shift the localized surface plasmon resonance (LSPR) and intensify recurrent light scattering between the AgNPs. For better overlap between surface plasmon resonance and the photoluminescence of fluorescent molecules with appropriately-sized silver nanoprisms, the slope efficiency of the PRL was greatly enhanced and the lasing threshold was obviously reduced. In addition, the photon lifetime for the DC-PVA/AgNPs film reveals an apparent decline around 1.39 ns owing to better coupling with LSPR. The stronger light scattering of samples with bigger-sized silver nanoprisms has been demonstrated by coherent back scattering measurements, which reveals a smaller transport mean free path around 3.3 mm. With a-stable analysis, it has been successfully demonstrated that the tail exponent a can be regarded as an identifier of the threshold of random lasing.
关键词： localized surface plasmon resonance,resonant energy transfer,silver nanoplates,light scattering enhancement,plasmonic random laser
更新于2025-09-19 17:13:59
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Calcium ion assisted fluorescence determination of microRNA-167 using carbon dotsa??labeled probe DNA and polydopamine-coated Fe3O4 nanoparticles
摘要： A selective and sensitive fluorescence biosensor is described for determination of microRNA-167 using fluorescent resonant energy transfer (FRET) strategy. The FRET system comprises carbon dots (CDs, donor) labeled with probe DNA (pDNA) and polydopamine (PDA)-coated Fe3O4 nanoparticles (Fe3O4@PDA NPs, acceptor). The CDs-pDNA can be absorbed onto the surface of Fe3O4@PDA NPs because of the strong π interaction between pDNA and PDA. With the enhanced adsorption ability of Fe3O4@PDA NPs by Ca2+, the fluorescence intensity of CDs at 445 nm (excitation at 360 nm) is quenched. In presence of microRNA-167, the hybridized complex of CDs-pDNA-microRNA-167 will be released from the surface of Fe3O4@PDA NPs due to the weak π interaction of the complex and PDA. This results in the fluorescence recovery of CDs. By application of twice-magnetic separation, the biosensor shows a wide linear range of 0.5–100 nM to microRNA-167 with a 76 pM detection limit. The method was applied to the determination of microRNA-167 in samples of total microRNA extractions from A. thaliana seedlings, and the recoveries ranged from 96.4 to 98.3%.
关键词： Fluorescent resonant energy transfer,Twice-magnetic separation,MicroRNA extractions,Hybridized complex,π interaction,Fluorescence biosensor
更新于2025-09-19 17:13:59
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Enhanced Energy Transfer in Doped Bifluorene Single Crystals: Prospects for Organic Lasers
摘要： Organic single crystals with long-range molecular order ensure enhanced carrier mobility and stability as well as emission outcoupling, which makes them attractive as gain medium for electrically pumped organic lasers. Unfortunately, effects of excitonic coupling introduce losses degrading optical performance in crystals, hence higher lasing thresholds are observed compared to amorphous films. Here, crystal doping strategy is investigated as a method to avoid pronounced reabsorption and annihilation losses associated with J-type excitonic coupling, while taking advantage of enhanced exciton transport for efficient energy transfer. Bifluorene-based derivatives linked with acetylene and ethylene rigid bridges are suitable as host and dopant system forming high-quality crystals doped at various concentrations (0.5–11.0%). Enhanced exciton transport in host crystal mediates picosecond host–dopant energy transfer enabling 100% transfer efficiency at lower doping concentrations compared to amorphous films. Amplified spontaneous emission threshold of 1.9 μJ cm?2 in 3.5% doped crystal is enabled by minimized exciton annihilation and emission reabsorption losses at optimal doping concentration.
关键词： long-range energy transport,organic single crystals,organic laser gain materials,amplified spontaneous emission,F?rster resonant energy transfer
更新于2025-09-12 10:27:22
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Rydberg-State-Resolved Resonant Energy Transfer in Cold Electric-Field-Controlled Intrabeam Collisions of NH <sub/>3</sub> with Rydberg He Atoms
摘要： The resonant transfer of energy from the inversion sublevels in NH3 to He atoms in triplet Rydberg states with principal quantum number n = 38 has been controlled using electric fields below 15 V/cm in intrabeam collisions at translational temperatures of ～1 K. The experiments were performed in pulsed supersonic beams of NH3 seeded in He at a ratio of 1:19. The He atoms were prepared in the metastable 1s2s 3S1 level in a pulsed electric discharge in the trailing part of the beams. The velocity slip between the heavy NH3 and the lighter metastable He was exploited to perform collision studies at center-of-mass collision speeds of ～70 m/s. Resonant energy transfer in the atom?molecule collisions was identified by Rydberg-state-selective electric-field ionization. The experimental data have been compared to a theoretical model of the resonant dipole?dipole interactions between the collision partners based on the impact parameter method.
关键词： NH3,resonant energy transfer,cold collisions,electric-field control,Rydberg states,He
更新于2025-09-12 10:27:22
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Quenched Stochastic Optical Reconstruction Microscopy (qSTORM) with Graphene Oxide
摘要： Quenched Stochastic Optical Reconstruction Microscopy (qSTORM) was demonstrated with graphene oxide sheets, peptides and bacteria; a method of contrast enhancement with super-resolution fluorescence microscopy. Individual sheets of graphene oxide (GO) were imaged with a resolution of 16 nm using the quenching of fluorescence emission by GO via its large Resonant Energy Transfer (RET) efficiency. The method was then extended to image self-assembled peptide aggregates (resolution 19 nm) and live bacterial cells (resolution 55 nm, the capsular structure of E. coli from urinary tract infections) with extremely low backgrounds and high contrasts (between one and two orders of magnitude contrast factor improvements that depended on the thickness of the graphene oxide layer used). Graphene oxide films combined with STORM imaging thus provide an extremely convenient method to image samples with large backgrounds due to non-specifically bound fluorophores (either due to excess labelling or autofluorescent molecules), which is a common occurrence in studies of both biological cells and soft-condensed matter. The GO quenches the fluorescence across a thin layer at distances of less than 15 nm. Graphene oxide films coated with thin layers (≤15 nm) of polystyrene, polymethylmethacrylate and polylysine are shown to be effective in producing high contrast qSTORM images, providing a convenient modulation of sample/substrate interactions. The GO coatings can also provide an increased image resolution and a factor of 2.3 improvement was observed with the peptide fibres using a feature of interest metric,when there was a large non-specifically bound background.
关键词： Quenched Stochastic Optical Reconstruction Microscopy,contrast enhancement,peptide aggregates,qSTORM,fluorescence quenching,RET,bacterial cells,Resonant Energy Transfer,graphene oxide,super-resolution fluorescence microscopy
更新于2025-09-10 09:29:36
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State resolved investigation of F?rster resonant energy transfer in collisions between polar molecules and Rydberg atoms
摘要： We perform a comprehensive investigation of F?rster resonant energy transfer in a room-temperature thermal mixture of ammonia molecules and rubidium Rydberg atoms. Fully state-resolved measurement of the Rydberg-atom populations is achieved by combining millimeter-wave state transfer with state-selective ?eld ionization. This allows aspects of the energy transfer process such as state dependence, ammonia pressure dependence, and dependence on the energy resonance condition to be investigated in detail. Our results pave the way for future quantum experiments combining polar molecules and Rydberg atoms.
关键词： state dependent collisions,polar molecules,Rydberg atoms,F?rster resonant energy transfer
更新于2025-09-09 09:28:46