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New Approach for Pulsed-Laser Testing That Mimics Heavy-Ion Charge Deposition Profiles
摘要： A novel approach for two-photon absorption (TPA) pulsed-laser testing produces extended charge deposition profiles that are analogous to those produced by heavy ions. In this approach, which utilizes an axicon rather than a spherical lens, the conventional Gaussian beam is replaced by a quasi-Bessel beam. The key feature of a quasi-Bessel beam, relevant to pulsed-laser single-event effects (PL-SEE) studies, is that its radial size (~1 μm) remains constant over the axial length of the beam (several 100s of μm) resulting in a charge-deposition profile that more closely mimics that produced by a heavy ion. This elongated charge distribution directly lends itself to a simple and intuitive description in terms of linear-energy transfer, or LET, facilitating laser/ion correlation studies. Experimental results comparing a conventional TPA PL-SEE focusing geometry and the axicon focusing geometry are presented for three different test vehicles: a 45-nm SOI nFET, a bulk silicon photodiode, and an LM 124 operational amplifier. Using the axicon approach, strong laser/ion correlation is observed in the silicon photodiode for single-event transients (SET) across a wide range of LETs. The correlation is achieved by “tuning” the laser to the desired LET rather than relying on pre-existing heavy-ion data and therefore this approach holds promise as a predictive tool.
关键词： single-event effect (SEE),silicon,Correlation methods,single-event transient (SET),heavy-ion testing,pulsed-laser,two-photon absorption,linear energy transfer (LET)
更新于2025-09-12 10:27:22
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Controlling multiphoton excited energy transfer from Tm <sup>3+</sup> to Yb <sup>3+</sup> ions by a phase-shaped femtosecond laser field
摘要： The ability to control the energy transfer in rare-earth ion-doped luminescent materials is very important for various related application areas such as color display, bio-labeling, and new light sources. Here, a phase-shaped femtosecond laser field is first proposed to control the transfer of multiphoton excited energy from Tm3+ to Yb3+ ions in co-doped glass ceramics. Tm3+ ions are first sensitized by femtosecond laser-induced multiphoton absorption, and then a highly efficient energy transfer occurs between the highly excited state Tm3+ sensitizers and the ground-state Yb3+ activators. The laser peak intensity and polarization dependences of the laser-induced luminescence intensities are shown to serve as proof of the multiphoton excited energy transfer pathway. The efficiency of the multiphoton excited energy transfer can be efficiently enhanced or completely suppressed by optimizing the spectral phase of the femtosecond laser with a feedback control strategy based on a genetic algorithm. A (1 + 2) resonance-mediated three-photon excitation model is presented to explain the experimental observations. This study provides a new way to induce and control the energy transfer in rare-earth ion-doped luminescent materials, and should have a positive contribution to the development of related applications.
关键词： energy transfer,rare-earth ions,femtosecond laser,luminescent materials,multiphoton absorption
更新于2025-09-12 10:27:22
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Energy transfer and tunable photoluminescence of Sr6Gd2Na2(PO4)6F2:Tb3+, Eu3+ phosphors for near-UV white LEDs
摘要： A series of apatite-type Sr6Gd2Na2(PO4)6F2:Tb3+, Eu3+ phosphors have been successfully synthesized by the high-temperature solid-state reaction method. Phase structures were examined based on X-ray diffraction, the results indicated that the obtained Sr6Gd2Na2(PO4)6F2:Tb3+, Eu3+ samples were well crystallized without impurity phase. The photoluminescence emission and excitation spectra and the decay curves were investigated in detail. The main energy transfer from Tb3+ to Eu3+ was verified to compliance with the dipole-quadrupole mechanism. The luminescence colors of the Sr6Gd2Na2(PO4)6F2:Tb3+, Eu3+ phosphors can be easily tuned from green light (0.2570, 0.3766) to white light (0.3674, 0.2813) by adjusting the proportion of Tb3+ and Eu3+ ions. The investigations indicated that the Sr6Gd2Na2(PO4)6F2:Tb3+, Eu3+ phosphors can be used as a qualified candidate for application in white light-emitting diodes.
关键词： Near-UV white LEDs,Phosphors,Sr6Gd2Na2(PO4)6F2:Tb3+,Energy transfer,Photoluminescence,Eu3+
更新于2025-09-12 10:27:22
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Understanding the nature of mean-field semiclassical light-matter dynamics: An investigation of energy transfer, electron-electron correlations, external driving, and long-time detailed balance
摘要： Semiclassical electrodynamics (with quantum matter plus classical electrodynamics fields) is an appealing approach for studying light-matter interactions, especially for realistic molecular systems. However, there is no unique semiclassical scheme. On the one hand, intermolecular interactions can be described instantaneously by static two-body interactions connecting two different molecules, while a classical transverse E field acts as a spectator at short distance; we will call this Hamiltonian no. I. On the other hand, intermolecular interactions can also be described as effects that are mediated exclusively through a classical one-body E field without any quantum effects at all (assuming we ignore electronic exchange); we will call this Hamiltonian no. II. Moreover, one can also mix these two different Hamiltonians into a third, hybrid Hamiltonian, which preserves quantum electron-electron correlations for lower excitations but describes higher excitations in a mean-field way. To investigate which semiclassical scheme is most reliable for practical use, here we study the real-time dynamics of a minimalistic many-site model—a pair of identical two-level systems (TLSs)—undergoing either resonance energy transfer (RET) or collectively driven dynamics. While both approaches (no. 1 and no. 2) perform reasonably well when there is no strong external excitation, we find that no single approach is perfect for all conditions (and all methods fail when a strong external field is applied). Each method has its own distinct problems: Hamiltonian no. I performs best for RET but behaves in a complicated manner for driven dynamics; Hamiltonian no. II is always stable, but obviously fails for RET at short distances. One key finding is that, for externally driven dynamics, a full configuration-interaction description of Hamiltonian no. I strongly overestimates the long-time electronic energy, highlighting the not obvious fact that, if one plans to merge quantum molecules with classical light, a full, exact treatment of electron-electron correlations can actually lead to worse results than a simple mean-field electronic structure treatment. Future work will need to investigate (i) how these algorithms behave in the context of more than a pair of TLSs and (ii) whether or not these algorithms can be improved in general by including crucial aspects of spontaneous emission.
关键词： resonance energy transfer,semiclassical electrodynamics,mean-field dynamics,light-matter interactions,electron-electron correlations
更新于2025-09-12 10:27:22
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Fast synthesis and energy transfer of the tunable single-phase white-emitting phosphor Li2Gd4(WO4)7:Dy3+, Tm3+ for WLEDs
摘要： A series of Dy3+ and Tm3+ co-doped Li2Gd4(WO4)7 (LGW) single-phase white phosphors were fast synthesized by microwave assisted solid-state reaction method. Single-ion doped LGW:Dy3+ and LGW:Tm3+ phosphors were synthesized to obtain quenching concentrations. The ideal white light (0.33, 0.33) locates on the straight line that connects the Commission Internationale de L'Eclairage (CIE) coordinates of LGW:Dy3+ and LGW:Tm3+. Therefore, Dy3+ and Tm3+ were selected to co-dope LGW to realize white light emission. By changing Dy3+ concentration, white light was obtained under the excitation wavelengths of 356 nm and 363 nm. Luminescence decay curves and the emission spectra of the co-doped phosphors were characterized to verify the existence of energy transfer between Tm3+ and Dy3+ in this single-phase phosphor. Energy transfer efficiency and energy transfer mechanism were investigated in detail. This fast synthesized single-phase white phosphor LGW:Dy3+, Tm3+ is a good candidate for the white light emitting diodes.
关键词： White emitting,Energy transfer,Single phase,Fast synthesis
更新于2025-09-12 10:27:22
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Synthesis and characterization of poly(methyl methacrylate) co-doped with Tb(tmhd)3 – Rhodamine B for luminescent optical fiber applications
摘要： Currently, there is a growing interest in the development of multi-colored materials based on the combination of two or more systems (organic or inorganic) as a strategy to take advantage of their combined physical or chemical properties. These multi-colored materials have found potential applications as sensors, amplifiers, and optical fibers. In this work, the physical characteristics of poly(methyl methacrylate) (PMMA) doped with Terbium(III)-tris-(2,2,6,6-tetramethyl-3,5-heptanedionate) (Tb(tmhd)3) at 1.57–1.58 mmol and Rhodamine B (RhB) at different concentrations were analyzed. The emission obtained from these samples (multichromophoric samples) varied as function of RhB concentration due to an efficient energy transfer process (33–65%). The role of PMMA as inert matrix that assists in the recombination process was confirmed by FTIR and Raman spectra analysis. Moreover, an improvement in thermal resistance of the materials was observed due to the presence of the dopants during the polymerization process.
关键词： Poly(methyl methacrylate),Rhodamine B,Tb(tmhd)3,Energy transfer,Luminescent optical fiber
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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A target analyte induced fluorescence band shift of piperazine modified carbon quantum dots: a specific visual detection method for oxytetracycline
摘要： Through the protection/deprotection of one amine group and the amidation reaction, piperazine was used to modify carbon quantum dots (CQDs) and successfully served as a medium to combine oxytetracyclines (OTC) in solution by hydrogen bonding and electrostatic interactions. Fluorescence resonance energy transfer (FRET) probably occurred between piperazine modified CQDs (P-CQDs) and combined OTC, which resulted in the red-shift of the fluorescence band. Besides superior specificity for examining, a good linear relationship between the maximum emission wavelength of P-CQDs and concentrations of OTC (0 to 10 lM) can be obtained, which provides a rapid and convenient visual fluorescence detection method of OTC.
关键词： carbon quantum dots,oxytetracycline,visual detection,fluorescence resonance energy transfer,piperazine
更新于2025-09-12 10:27:22
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High perovskite-to-manganese energy transfer efficiency in single-component white-emitting Mn-doped halide perovskite quantum dots
摘要： Taking advantages of negligible reabsorption and no phase separation, single-component white-emitting phosphors are believed as new promising color conversion materials for white light-emitting diodes. As a potential candidate, Mn-doped lead halide perovskites are studied intensively, but rare works can realize pure white emission with a single component due to the challenge for realizing sufficient energy transfer efficiency from perovskite to Mn at the desirable emission wavelengths. In this work, we reported the synthesis of single-component white light halide perovskite quantum dots (QDs) by doping Mn into the host of CsPb(Cl/Br)3@CsPb(Cl/Br)x core–amorphous shell (CAS). The small size of zero-dimensional core in CAS structure has a strong quantum confinement effect, which can enhance the energy transfer efficiency from halide perovskite to Mn impurity dramatically. Our result shows 19.3 times higher energy transfer efficiency for Mn-doped CAS than that of ordinary Mn-doped CsPb(Cl/Br)3 nanocubes. As a result, as-prepared Mn-doped CAS QDs give rise to a white light emission with Commission Internationale de l’Eclairage (CIE) color coordinates of (0.37, 0.33). After blending with polystyrene (PS), Mn-doped CAS QDs can be used as a single-component color conversion material for assembling white light LEDs.
关键词： energy transfer efficiency,white-emitting phosphors,white light LEDs,Mn-doped lead halide perovskites,quantum dots
更新于2025-09-12 10:27:22
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Luminescence properties of Sm3+ and Dy3+ co-doped BaY2ZnO5 phosphor for white LED
摘要： Single-phased warm-white-emitting BaY2ZnO5:Dy3+, Sm3+ phosphors were synthesized by a high-temperature solid state reaction method. The crystal structure, luminescence properties, decay lifetimes, thermal stability and internal quantum efficiency (IQE) were investigated. Under 354 nm excitation, the emission spectrum exhibits the characteristic transitions of Sm3+ and Dy3+ and energy transfer mechanism are determined to be the dipole-dipole interactions. Due to the energy transfer from Dy3+ to Sm3+, the color tones and correlated color temperature (CCT) can be changed from near cool-white to warm-white when adjusting Sm3+ concentrations. The optimal BaY2ZnO5: 0.14Dy3+, 0.04Sm3+ emits warm-white light with CIE coordinates of (0.404, 0.367), low CCT of 3337 K, activation energy of 0.2389 eV and IQE of 61.5%, making it as a promising candidate white-emitting phosphor for LEDs application.
关键词： Phosphors,Luminescence,Optical materials and properties,Energy transfer
更新于2025-09-12 10:27:22