- 标题
- 摘要
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- 实验方案
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Energy transfer phenomenon of Gd3+ to excited ground state of Eu3+ ions in Li2O-BaO-Gd2O3-SiO2-Eu2O3 glasses
摘要： Li2O-BaO-Gd2O3-SiO2 glasses with different concentration of Eu3+ ions were developed by the traditional melt quenching technique and characterized via FTIR, absorption, excitation, emission and CIE color coordinates analysis for visible red emission application. The FTIR shows strong band at position 740 cm-1 which is attributed to Si-O-Si symmetric stretching mode. Density and molar volume of LBGSEu glasses increases with Eu3+ ions concentration. The covalent nature of bond between the Eu3+ ions and surrounding ligands was confirmed from the bonding parameter (δ). From absorption spectra JO-parameters and oscillator strength are evaluated for LBGSEu6 glass. From JO-parameters, Eu3+ ions have asymmetric coordination environment and stronger covalency. The phonon line PSB (22522 cm-1) confirm the phonon energy ≈ 971 cm-1, that corresponds to the energy of one phonon associated with maximum energy of the vibrational mode couple to Eu3+ ions. Under 275 nm and 393 nm excitation, intense red emission was observed at 613 nm, we observe efficient energy transfer phenomena from Gd3+ → Eu3+ in these glasses. Increasing trend of IR with increasing concentration of Eu2O3 indicates the asymmetric environment around Eu3+ ions in LBGS. Moreover from JO analysis, LBGS glasses have high capability for red laser device with high lasing power and energy extraction ratio. The fluorescence lifetimes show decreasing trend in lifetime with increasing concentration of Eu2O3 is due to radiative transition. From CIE color coordinate, the CIE color coordinates of LBGSEu6 glass fall in reddish region close to orange region and can be useful for optical display devices.
关键词： Judd-Ofelt analysis,Silicate glasses,Energy transfer,emission cross sections,Rare earth
更新于2025-09-23 15:21:01
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An ultrasensitive homogeneous aptasensor for carcinoembryonic antigen based on upconversion fluorescence resonance energy transfer
摘要： Carcinoembryonic antigen (CEA) has been recognized as one of the most important tumor markers. Herein, we reported an ultrasensitive homogeneous aptasensor based on fluorescence resonance energy transfer (FRET) between upconversion nanoparticles (UCNPs) and graphene oxide (GO) for CEA detection. The CEA aptamer modified UCNPs can bind to the surface of GO through π-π stacking interaction, resulting in fluorescence quenching due to the energy transfer from UCNPs to GO. After the introduction of CEA, the CEA aptamer preferentially combined with CEA to form three-dimensional structure which made UCNPs-aptamer dissociate from the GO, blocking the energy transfer process. The fluorescence of UCNPs was accordingly restored in a CEA concentration-dependent manner both aqueous solution and human serum samples. The aptasensor could monitor CEA level directly in human serum and the results were strongly correlated with commercial chemiluminescence kits. The excellent detection performance suggested promising prospect of the aptasensor in practical application.
关键词： Upconversion Nanoparticles,Graphene Oxide,Fluorescence Resonance Energy Transfer,CEA,Aptasensor
更新于2025-09-23 15:21:01
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Tunable bluea??greena??emitting Na4CaSi3O9:Ce3+,Li+,Tb3+ phosphor with energy transfer for near-UV white LEDs
摘要： Phosphor-converted white light emitting diodes (w-LEDs), with high luminous ef?ciency, low energy consumption, extended lifetime, and eco-friendly nature, have revolutionized various industries. Among them, an alkaline earth silicate-based phosphor host, Na4CaSi3O9, shows good crystal structure stability and ?exible properties for diverse application. Here, Ce3t/Lit and Tb3t/Lit co-doped Na4CaSi3O9 phosphors are fabricated by the standard solid-state reaction approach. The Ce3t/Lit-activated phosphors show strong absorption within 200e400 nm and exhibit a blue emission centered at 423 nm. The quenching concentration of Ce3t appears at x ? 0.05 and can be attributed to the dipoleequadrupole interaction. When Tb3t ions are co-doped, the Na4CaSi3O9:Ce3t/Lit phosphor emission can be adjusted from blue to green under the irradiation of 365 nm through the dipoleedipole interaction induced energy transfer from Ce3t to Tb3t ions with a maximum value of 28.32%. This study highlights the Na4CaSi3O9:Ce3t/Lit,Tb3t/Lit phosphors as a new and ef?cient material for w-LED applications.
关键词： Phosphor,Solid-state reaction,Luminescence,LED,Energy transfer
更新于2025-09-23 15:21:01
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Dual coupled effects of low concentration gold nanorods on energy transfer and luminescence enhancement in Eu/Tb co-doped films
摘要： Eu/Tb co-doped films with low concentration gold nanorods have been prepared using the solution process. The luminescence spectra investigations indicate that the introduction of nanorods can effectively enhance the energy transfer from Tb to Eu under excitation of 292 nm, because of the plasmonic coupling with excited Tb complex. Under excitation of 360 nm, the emission at 612 nm is enhanced, the enhancement factor increases and then decreases as the molar ratio of Tb and Eu increases. The luminescence enhancement is attributed to the metal enhanced luminescence resulting from plasmonic coupling with excited Eu complex. The dual effects of LSPR on energy transfer and emission enhancement are both observed. More details on the luminescence of Eu/Tb co-doped films with nanorods are demonstrated, which gain a deeper understanding of the interactions luminescent-particle and luminescent-luminescent.
关键词： Enhanced luminescence,Eu,Plasmonic nanorods,Tb,Energy transfer
更新于2025-09-23 15:21:01
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Significant enhancement of light-harvesting efficiency through the formation of [2]pseudorotaxane with γ-cyclodextrin based on a bolaamphiphile of salicylaldehyde azine moiety
摘要： In this work, we have designed and synthesized a bolaamphiphile of salicylaldehyde azine (BSA), which can form [2]pseudorotaxane with γ-cyclodextrin (BSA@γ-CD) in aqueous solution and exhibit remarkable enhancement of the fluorescence emission. Both BSA and BSA@γ-CD assembly can spontaneously form spherical aggregates in aqueous solution with diameter at about 30 nm and 20 nm, respectively. By using BSA and BSA@γ-CD as energy donor and sulforhodamine 101 (SR101) as energy acceptor, we fabricated two artificial light-harvesting systems in aqueous solution. Significantly, an efficient energy transfer process was revealed to occur between the BSA or BSA@γ-CD assembly and the loaded SR101 to obtain high energy transfer efficiency and antenna effect. More importantly, energy transfer efficiency and antenna effect can be greatly improved in these two systems only just by addition of γ-CD.
关键词： Energy transfer,Fluorescence enhancement,Pseudorotaxane,Light-harvesting,Self-assembly
更新于2025-09-23 15:21:01
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Water Soluble Fluorescent Graphene Nanodots
摘要： Water soluble fluorescent graphene nanodots (GND) have been successfully prepared through a bottom up approach from brominated pyrene via alkaline hydrothermal condensation. FT-IR, UV-Vis, Raman, XRD, AFM, and TEM studies have shown the formation of (cid:2)OH group rich nano-dots having graphene features with an approximate size of 90 nm. Steady state and 3D fluorescence studies have shown efficient fluorescence emission with maximum at 540 nm upon excitation at 450 nm in pH (cid:3) 7. Plasmid deoxyribonucleic acid (plasmid DNA) and bovine serum albumin (BSA) have shown their interaction with GND, which was studied via fluorescence quenching of GND and BSA, respectively. Selective quenching of the Fo¨ rster resonance energy transfer (FRET) of BSA-GND conjugate via ascorbic acid (AA) has been used to construct a calibration curve for AA estimation with a linear range and limit of detection of 34.00–112.00 mmole/L respectively. GND has also shown and 31.343 mmole/L, turn offchemosensing towards concentration-dependent heavy metals like Pb2 +, Cu2 +, Hg2 + and Zn2 +. In-vitromulti-color fluorescence imaging has been observed in GND-labelled HeLa (human cervical cancer) and NIH-3T3 (mouse embryonic fibroblast) cell lines with better uptake by HeLa cells. GND also has shown very high viability for both the cell lines up to the tested concentration of 300 mg/mL.
关键词： fluorescence,graphene nanodots,F?rster resonance energy transfer,brominated pyrene,bovine serum albumin
更新于2025-09-23 15:21:01
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Plasmon-Assisted Energy Transfer in Hybrid Nanosystems
摘要： While direct optical excitation of carbon nanotubes activates only the tube species strictly matching the excitation source, excitation energy transfer processes provide a single excitation channel for all the nanotubes species in a sample. The requirement of an overlap between donor emission and acceptor absorption limits the poll of donors able to trasfer their excitation to the tubes, leaving the high-energy part of the solar spectrum excluded from such processes. Here it is shown that the grafting of small metal nano-particles to the tubes alters those rules, enabling energy transfer process from molecules for which the standard energy transfer process is strongly suppressed. The onset of an energy transfer band in the UV/blue spectral region is demonstrated for an hybrid gold-pyrene-nanotube system, yielding collective emission from all the tubes present in our samples upon excitation of pyrene.
关键词： gold nanoparticles,pyrene dye,carbon nanotubes,plasmonic hybrids,energy transfer
更新于2025-09-23 15:21:01
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On the use of multiple stacked active layers in organic photovoltaic cells
摘要： In the field of organic photovoltaic cells (OPVs), ternary planar heterojunction allows widening absorption range. Optimization of the energy levels at the organic interfaces is the first task to achieve in order to obtain OPVs with high efficiency. In ternary OPVs, carrier mobility, charge transfer and presence of energy transfer are determinant. Here, we compare the performances of different, binary (electron donor/fullerene) and ternary (electron donor/ambipolar material/fullerene) combinations of small organic molecules in planar heterojunction (PHJ) cells. We chose the different ED molecules in order to investigate the different possible band scheme alignments. The study shows that if the open circuit voltage (Voc) is limited by the energy levels of the outer layers, i.e. the difference between the lowest unoccupied molecular orbital (LUMO) of the electron acceptor and the highest occupied molecular orbital (HOMO) of the outer electron donor layer, the energy loss can be smaller than 0.2 eV. If efficient ternary OPVs need global energy offset higher than the exciton energy to separate the charges of the exciton, the distribution of this offset between DLUMO and DHOMO is not critical. The mobility value of the carriers in the intercalated layer is determinant in obtaining performance of OPVs. Overlap between the photoluminescence of ED and the optical absorption of EDA is primordial for good energy transfer. The highest OPV efficiency improvement is obtained with organic materials such as ED and EDA that have the same HOMO and similar hole mobility which give homogeneous thin layers.
关键词： organic photovoltaic cells,energy levels,energy transfer,carrier mobility,charge transfer,ternary planar heterojunction
更新于2025-09-23 15:19:57
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Mechanism of Mn emission: Energy transfer vs charge transfer dynamics in Mn-doped quantum dots
摘要： In the quest for new functional materials, transition metal doping in semiconductors has attracted significant attention, wherein introduction of dopant atoms alters a range of physical properties of the host such as its optical, magnetic, and electronic properties. Hence, the choice of appropriate dopants to meet the current challenges makes semiconductor doping a highly versatile field. In the past, Mn doping in II-VI semiconductors has been extensively studied. The interest in these systems arises from a prominent orange emission from an optically forbidden state. An extended debate in the literature spanning the last three decades has so far shed light on various anomalous properties of Mn emission, specifically in quantum-confined systems leading to more questions. In this perspective, we review the literature with specific emphasis on the mechanism of Mn emission and an understanding of the electron–hole pathway during the excitation and de-excitation process in doped quantum dots. We explore various phenomena of energy and charge transfer mechanisms along with experiments in support of these phenomena which can eventually lead to a better understanding of spin driven optoelectronics.
关键词： Mn emission,optoelectronics,charge transfer,energy transfer,quantum dots
更新于2025-09-23 15:19:57
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Photoinduced charge carrier dynamics in a ZnSe quantum dot-attached CdTe system
摘要： A new nanohybrid material is prepared by attaching CdTe nanoneedles (NNs) to surface-modified ZnSe quantum dots (QDs). The NNs and QDs are prepared by a colloidal synthesis method in an aqueous alkaline medium. The surface modification and the attachment of nanostructures are achieved by a bifunctional ligand 3-mercaptopropionic acid (3-MPA). The band gap of the ZnSe QDs is varied by controlling the size of the QDs in order to get the maximum overlap between the absorption band of the CdTe NNs and the emission band of the ZnSe QDs, which is a prerequisite for effective charge/energy transfer. The possibility of photoinduced charge transfer (PCT) and F?rster resonance energy transfer (FRET) from the donor (QDs) to the acceptor (NNs) has been assessed. Very fast (less than 800 ps) PCT and FRET from QDs to NNs occur because the emission band of QDs overlaps with the absorption band of NNs. The calculated large value of the overlapping integral, J(λ) ～4.5 × 1019 M?1 cm?1 nm4, of the donor and the acceptor bands proves the feasibility of energy transfer. These findings suggest that the ZnSe QDs can exchange photoinduced energy with the CdTe NNs effectively over a wide distance in a CdTe–ZnSe nanohybrid.
关键词： quantum dots,zinc selenide,F?rster resonance energy transfer,cadmium telluride,nanohybrid,charge transfer
更新于2025-09-23 15:19:57