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Synthesis of All-Inorganic Cd-Doped CsPbCl <sub/>3</sub> Perovskite Nanocrystals with Dual-Wavelength Emission
摘要： Doped lead halide perovskite nanocrystals (NCs) have garnered significant attention due to their superior optoelectronic properties. Here, we report a synthesis of Cd-doped CsPbCl3 NCs by decoupling Pb- and Cl-precursors in a hot injection method. The resulting Cd-doped perovskite NCs manifest a dual-wavelength emission profile with the first reported example of Cd-dopant emission. By controlling Cd-dopant concentration, the emission profile can be tuned with a dopant emission quantum yield up to 8%. A new secondary emission (~610 nm) is induced by an energy transfer process from photo-excited hosts to Cd-dopants, and a subsequent electronic transition from excited state (3Eg) to ground state (1A1g) of [CdCl6]4- units. This electronic transition matches well with a first-principles density functional theory calculation. Further, the optical behavior of Cd-doped CsPbCl3 NCs can be altered through post-synthetic anion-exchange reactions. Our studies present a new model system for doping chemistry studies in semiconductors for various optoelectronic applications.
关键词： Energy transfer,Doping,Perovskite,Anion exchange,Nanocrystals
更新于2025-09-10 09:29:36
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Tunable emission of LiCa3MgV3O12:Bi3+ via energy transfer and changing excitation wavelength
摘要： LiCa3MgV3O12:Bi3+ phosphor is successfully synthesized by the high-temperature solid-state reaction method in air. The crystal structures and luminescence properties are investigated. Excitation/emission bands of LiCa3MgV3O12:Bi3+ phosphor show red-shift with increasing the monitored/excitation wavelengths from short to long. The doping of Bi3+ ion can result in the host LiCa3MgV3O12 lattice distortion and the energy transfer to Bi3+. The tunable emission of LiCa3MgV3O12:Bi3+ phosphor from blue-green to yellow can be observed with increasing Bi3+ concentration from 0 to 8 mol%. The chromaticity coordinates of LiCa(3-x)MgV3O12:xBi3+ phosphors can change from (0.2393, 0.3260) to (0.4358, 0.4472) with increasing Bi3+ concentration from 0 to 8 mol%. The existence of VO4 3? → Bi3+ ET in LiCa3MgV3O12:Bi3+ phosphor is indicated by the luminescence properties. The luminous mechanism of LiCa3MgV3O12:Bi3+ phosphor is explained by the con?gurational coordinate diagrams of VO4 3? and Bi3+. The experimental results are helpful for the luminescence property researches of other Bi3+-doped luminescence materials.
关键词： Energy transfer,Tunable emission,LiCa3MgV3O12: Bi3+ ions,Vanadates
更新于2025-09-10 09:29:36
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Optically-Active Nanocrystals for Inner Filter Effect-Based Fluorescence Sensing: Achieving Better Spectral Overlap
摘要： Among various photophysical processes for fluorescence modulation, inner filter effect (IFE) is well-known for its simplicity and no requirement of the distances between the fluorophores and the corresponding modulators. Theoretically, the key to maximize the sensitivity of IFE-based fluorescent assays is to enlarge the overlap between the absorption of the absorber and the excitation/emission of the fluorophores. However, it is difficult to achieve perfect spectral overlap for IFE in conventional organic fluorophores with constant excitation/emission. The emergence of various optically-active nanocrystals greatly revolutionize the IFE-based fluorescent sensing. Therefore in this critical review, we first made an introduction to IFE from the viewpoint of its photophysical process. Particularly, the similarities and differences of IFE and FRET for better understanding of IFE are discussed, and the general rules for verification of IFE are proposed. The use of various optically-active nanocrystals for enhanced IFE-based sensing is especially concerned in this review.
关键词： fluorescence resonance energy transfer,Inner filter effect,spectral overlap,fluorescent sensors,optically-active nanocrystals,tunable spectra
更新于2025-09-10 09:29:36
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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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Photosensitization and Photocatalysis - Perspectives in Organic Synthesis
摘要： Photochemical sensitization and photocatalysis have very similar definitions and are closely related. Each of the two terms are preferentially used in different scientific communities. Three types of processes are discussed: (1) sensitization involving energy transfer, (2) photocatalysis in which hydrogen abstraction plays a key role and (3) photoredox catalysis in which electron transfer is involved. The processes are discussed in connection with [2+2] photocycloadditions and C-H activation, which are of particular interest for organic synthesis.
关键词： [2+2] Photocycloaddition,Photosensitization,Energy transfer,Hydrogen atom transfer,Electron transfer,C-H activation,Photocatalysis
更新于2025-09-09 09:28:46
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[ASME ASME 2018 Conference on Smart Materials, Adaptive Structures and Intelligent Systems - San Antonio, Texas, USA (Monday 10 September 2018)] Volume 1: Development and Characterization of Multifunctional Materials; Modeling, Simulation, and Control of Adaptive Systems; Integrated System Design and Implementation - Essentially Nonlinear Piezoelectric Attachment for Aeroelastic Flutter Suppression
摘要： Various researchers have investigated the behavior of a linear mechanical oscillator weakly coupled to a nonlinear mechanical attachment that has essential stiffness nonlinearity. Under certain conditions, the essentially nonlinear attachment acts as a nonlinear energy sink (NES) and one-way energy transfer from the main structure to the attachment can be achieved. Since an essentially nonlinear attachment does not possess any preferential resonance frequency, they have increased robustness against detuning, enabling frequency-wise wideband performance. In this work, the interactions between an essentially nonlinear piezoelectric an electromechanically coupled two-degree-of-freedom (2-DOF) aeroelastic typical section are studied. The governing equations of typical section with piezoelectric coupling added to the plunge DOF are presented. An equivalent electrical model of the coupled aeroelastic system is presented and combined to a nonlinear shunt circuit. The performance of the piezoelectric NES to modify the aeroelastic behavior of the typical section is discussed using the short-circuit condition as a reference case. Furthermore, the robustness of the piezoelectric NES against detuning is also investigated by changing some parameters of the typical section.
关键词： piezoelectric,aeroelastic,flutter suppression,nonlinear energy sink,targeted energy transfer
更新于2025-09-09 09:28:46
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Low-Energy Chlorophylls in Fucoxanthin Chlorophyll <i>a/c</i> -Binding Protein Conduct Excitation Energy Transfer to Photosystem I in Diatoms
摘要： Photosynthetic organisms handle solar energy precisely to achieve efficient photochemical reactions. Since there are a wide variety of light-harvesting antennas in oxyphototrophs, the excitation-energy-transfer mechanisms are thought to differ significantly. In this study, we compared excitation-energy dynamics between photosystem I (PSI) cores and a complex between PSI and fucoxanthin chlorophyll a/c-binding protein (PSI-FCPI) isolated from a diatom, Chaetoceros gracilis, by means of picosecond time-resolved fluorescence analyses. Time-resolved spectra measured at 77 K clearly show that low-energy Chls in the FCPI transfers not only most of the excitation energy to the reaction-center Chls in the PSI cores but also the remaining energy to carotenoids for quenching. Under room-temperature conditions, the energy in the low-energy Chls is rapidly equilibrated on Chls in the PSI cores by uphill energy transfer within a few tens of ps. These findings provide solid evidence that the low-energy Chls in the FCPI contribute to the photochemical reactions in PSI.
关键词： light-harvesting antennas,low-energy Chls,Photosynthetic organisms,PSI-FCPI,excitation-energy-transfer mechanisms,photochemical reactions
更新于2025-09-09 09:28:46
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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
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Cooperative Chirality and Sequential Energy Transfer in Supramolecular Light-harvesting Nanotube
摘要： By constructing a supramolecular light-harvesting chiral nanotube in aqueous phase, we demonstrated the cooperative energy and chirality transfer that revealed some new aspects. It was found that a cyanostilbene-appended glutamate compound (CG) self-assembled into helical nanotubes exhibiting both supramolecular chirality and circularly polarized luminescence (CPL). When two achiral acceptors ThT and AO with different energy bands were co-assembled with the nanotube, the CG nanotube could transfer its chirality to both of the acceptors. The excitation energy could be transferred to ThT but only be sequentially transferred to AO. During such process, the CPL ascribed to the acceptor could be sequentially amplified. This work provides a new insight into the understanding the cooperative chirality and energy transfer in a chiral supramolecular system, which is more similar to the natural light-harvesting antennas.
关键词： Supramolecular chirality,Energy transfer,Light-harvesting,Circularly polarized luminescence,Supramolecular nanotube
更新于2025-09-09 09:28:46
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Efficient improvement of 2.7μm luminescence of Er3+:oxyfluorideglass containing gallium by Yb3+ions codoping
摘要： Mid-infrared laser materials with low phonon energy have significant applications. However, the development of available glass systems for high-power laser gain medium have posed a great challenge. Therefore, we investigated the 2.7 μm spectroscopic properties of Er3+/Yb3+-codopedoxyfluoride glass containing gallium, which were prepared by typically melting and quenching methods. The 2.7 μm luminescence properties of the Er3+/Yb3+-codopedoxyfluoride glass containing gallium were recorded by a 980 nm laser diode. The Judd–Ofelt parameters, decay curves, emission cross section, energy transfer efficiency, and quantum efficiency were calculated. The maximum emission cross section of YbFGa-0.5 is 1.63×10?20 cm2 by 980 nm excitation. The energy transfer efficiency is calculated to be 77.8% for the YbFGa-0.5 glass around 2700 nm. The quantum efficiency at 1530 nm is 65.6%. The resulting reveals that the best doping concentration ratio of Er3+:Yb3+ ions is 1:0.5, and suggests an effective energy transfer from Yb3+ to Er3+ ions.
关键词： optical materials,rare-earth ions doped,optical spectroscopy,mid-infrared,energy transfer
更新于2025-09-09 09:28:46