Journal of Luminescence最新文献

Latent fingerprint detection is one of the promising technique in forensic science. Here, a cation replacement strategy in Eu³⁺-activated K_1-yNa_yGaGeO₄ phosphor under excitation by near ultraviolet (NUV) light was proposed for the first time. The corresponding crystal structure, luminescent property, thermal stability, and color purity were systematically investigated. These results indicate that the high photoluminescence (PL) intensity and prominent ultraviolet absorption of the phosphors can contribute to obvious suppression of background interference of substrate and good visualization for the fluorescent LFP images. The optimized K_0.65Na_0.15GaGeO₄:0.2Eu³⁺ phosphor reveals a great thermal stability and color shift resistance from 300 to 500 K. The Commission International del'Eclairage (CIE) chromaticity coordinates of K_0.65Na_0.15GaGeO₄:0.2Eu³⁺ were measured to be (0.6637,0.3409), and the color purity was calculated as 91.1 %. The obtained results suggest that the K_0.65Na_0.15GaGeO₄:0.2Eu³⁺ phosphor exhibits good potential for high resolution and high sensitivity LFP detection and LED application.

Zero-dimensional (0D) organic-inorganic Cu(I)-based halides have garnered significant attention due to their low toxicity, efficient emission, and moderate fabrication conditions. However, the challenge remains in developing stable and efficient 0D hybrid Cu(I)-based halides for effective X-ray imaging. In this study, a yellow-emitting 0D hybrid copper halide, (ETPP)₂Cu₂I₄ (Ethyl triphenylphosphonium, ETPP), was successfully synthesized via a slow evaporation method. This compound demonstrated an impressive steady-state light yield of 23,200 photons/MeV under X-ray radiation and an ultralow detection limit of 150.9 nGy_air s⁻¹, approximately 35 times lower than the standard medical examination dosage. Utilizing a vacuum-filtration method, we fabricated a flexible film that outperforms traditional methods and achieved an exceptional X-ray imaging resolution of 16.0 lp/mm. This study introduces a novel approach to fabricating high-performance X-ray imaging scintillators based on 0D Cu-based halides, showcasing excellent scintillation performance and stability for non-destructive testing.

Mechanical stimulus-responsive materials are generally considered to be closely related to molecular packing in the solid state, underscoring the significance of regulating molecular packing via precise molecular design. In this study, flexible alkyl substituents were employed to adjust the molecular packing. By modifying alkyl substituents, predictable changes in the molecular packing of their derivatives were observed, resulting in adjustable ML properties. The DPA-PYZ-TB with a tert-butyl-side chain exhibited strong ML and MC stimulus response signals. The enhanced ML and MC performance can be attributed to the effective suppression of non-radiation through the helical crystal arrangement and strong intermolecular interactions. The relationship between molecular arrangement and ML/MC properties was validated through analysis of the single crystal structure and corresponding experimental results. This study offers valuable insights into the enigmatic ML process and the development of efficient luminous materials that utilize both MC and ML.

The efficient design of dual-sensing mechanisms for fluorescent probes holds significant implications for real-time monitoring of acetylcholinesterase (AChE) under oxidative stress. In this study, we employed density functional theory (DFT) and time-dependent density functional theory (TD-DFT) to investigate the fluorescence detection mechanisms of 2-(2-hydroxyphenyl)benzothiazole derivatives SNCN-AE and SNC-AE. We proposed a fluorescence detection method based on the mechanisms of excited-state intramolecular proton transfer (ESIPT) and photo-induced electron transfer (PeT). Computational results indicate that the fluorescence quenching of SNCN-AE and SNC-AE results from the typical PeT process initiated by the dimethyl carbamate ester moiety. Upon reaction with the AChE, the electron donor is replaced by the hydroxyl group, and the PeT is suppressed. The redshift of emission wavelength arises from the ESIPT process rather than the ICT mechanism, as evidenced by the absence of charge transfer phenomena in the computed frontier molecular orbitals. This study provides a novel insight for the further development of fluorescence probes in the field of biomedicine, based on the PeT-ESIPT mechanism regulation.

The appearance of the ultraviolet Bi³⁺-related emission band in the thermally stimulated luminescence (TSL) spectrum is observed around 465 K after selective irradiation of the YAlO₃:Bi perovskite in the Bi³⁺-related absorption bands. The excitation spectrum of the TSL glow curve peak at 465 K, activation energies of its creation by photons of different energies, and the dependence of the TSL peak intensity on the irradiation duration are measured. The origin of the optically created electron centers and the mechanisms of photostimulated creation of the electron and hole centers under irradiation in the Bi³⁺-related absorption bands of YAlO₃:Bi are discussed. The TSL glow curve peak at 465 K is suggested to appear as a result of electrons release from the electron centers intrinsic to the YAlO₃ lattice and their recombination with the hole Bi⁴⁺ centers. The same processes are shown to take place in the X-ray-irradiated YAlO₃:Bi perovskite. The obtained results are important for possible applications of the investigated material in thermoluminescent dosimetry.

Luminescence properties of strontium fluoride transparent ceramics with various TbF₃ amounts (0.1, 0.5, and 1 %) were investigated. Scintillation peaks derived from the electronic transitions between 4f levels in Tb³⁺ were observed. The observed scintillation decay times of approximately 8.3 ms were typical for the electronic transitions in Tb³⁺. Furthermore, the Tb-doped strontium fluoride transparent ceramics showed thermoluminescence and optically stimulated luminescence (OSL) with Tb³⁺ serving as the recombination center. The most intense thermoluminescence signal was detected from the 0.1 % Tb-doped transparent ceramic within the range of 0.01–100 mGy. OSL stimulated by 600 nm light of the same material was the most intense, and its lowest detectable limit was about 100 mGy.

Despite the appreciable high color-purity green-light of chiral Tb³⁺-complexes, it remains a great challenge to enable their both high quantum efficiency and large circularly polarized light (CPL) activity. Herein, through the self-assemble of the chiral Salen-type bis-Schiff-base ligand (S,S)-H₂L or (R,R)-H₂L with Zn(OAc)₂·2H₂O and Ln (NO₃)₃·6H₂O (Ln = La, Tb, Gd), two series of chiral Zn(II)-Ln (III)-heterobinuclear enantiomers [Zn ((S,S)-L)Ln (μ₁-OAc)(μ₂-NO₃)₂] (Ln = La, 1; Tb, 2; Gd, 3) or [Zn ((R,R)-L)Ln (μ₁-OAc)(μ₂-NO₃)₂] (Ln = La, 4; Tb, 5; Gd, 6) were afforded, respectively. Photophysical study shows that the destabilized ³π-π* energy level upon Zn²⁺ coordination, is confirmed to effectively sensitize of the Tb³⁺-centered green-light for the two chiral complexes [Zn ((S,S)-L)Tb (μ₁-OAc)(μ₂-NO₃)₂] (2) and [Zn ((R,R)-L)Tb (μ₁-OAc)(μ₂-NO₃)₂] (5). The merits of efficient (${\Phi }_{\text{Tb}}^L$ = 5.6–6.2 %) Tb³⁺-centered green-light and strong CPL activity (|g_PL| = 0.03, ⁵D₄→⁷F₃ transition), engender chiral Zn(II)-Tb(III)-Salen complexes like 2 and 5 a new platform to ideal chiral organo-Tb³⁺ candidates.

ZIF-8 (zinc-methylimidazolate framework-8) has shown promising applications as a fluorescence sensing platform, particularly in fluorescence quenching sensors for various biological and chemical analyses and detections. However, the impact of the morphology of ZIF-8 crystals on their performance of biomolecule detection, especially DNA detection, remains to be explored. In this study, six types of ZIF-8 crystals with different morphology (cubic, rough octahedral, flakes, rhombic, dodecahedral, and hexapod) are successfully synthesized by incorporating different concentrations of the surfactant/end-capping agent, namely cetyltrimethylammonium bromide (CTAB) and/or tris(hydroxymethyl)aminomethane (TRIS). These crystals are characterized in terms of morphology, crystal structure, specific surface area, and electrostatic adsorption capacity. Subsequently, these morphologically different ZIF-8 crystals are combined with fluorophore carboxyfluorescein (FAM)-labeled single-stranded DNA (ss-DNA) to form FAM-DNA@ZIF-8 biosensor. Then, their fluorescence quenching efficiency is characterized by using the fluorescence spectroscopy. The measurement results show that, due to its higher external specific surface area and zeta potential thereby higher electrostatic adsorption capacity, the cubic ZIF-8 crystal can effectively capture more FAM-DNA molecules through the electrostatic adsorption and achieve high fluorescence quenching efficiency via the fluorescence resonance energy transfer mechanism. Thus, the fluorescence quenching efficiency of the cubic FAM-DNA@ZIF-8 reaches up to 98.1 %. Finally, the cubic FAM-DNA@ZIF-8 biosensor is used to detect the complementary target HIV-1 DNA via the fluorescence recovery. The experimental results show that the fluorescence recovery efficiency of the FAM-DNA@ZIF-8 reaches up to 40.8 upon the addition of complementary target ssDNA, significantly higher than the recovery efficiency when non-complementary target DNA is introduced. Also, both fluorescence quenching efficiency and recovery efficiency of the cubic FAM-DNA@ZIF-8 are much higher than those of the reported biosensors based on ZIF-8 crystals with non-optimal morphology. Additionally, the fluorescence recovery sensitivity of the biosensor is 0.536/(nM⋅mL), with a detection limit as low as 1.37 nM. In addition, its detection performance remains almost unchanged after ten days of storage. These findings provide valuable insights for optimizing ZIF-8-based DNA biosensor.

Optical scatterer additives play a critical role in enhancing the light conversion efficiency and uniformity of quantum dot-converted light-emitting diodes (Qc-LEDs). This study investigates the impact of optical characteristics and morphology of nanoscatterer on the light conversion and extraction efficiency of Qc-LEDs. Various metal oxides and boron nitride nanoparticles and nanoplates with different diffraction index were selected to carry out the study. Finite-Difference Time-Domain (FDTD) simulation was employed to evaluate the scattering effect of various nanosphere and nanoplate scatterers on the optical performance of the Qc-LEDs. The simulation results revealed that the hybrid nanoscatterer integrates the forward-scattering from the nanosphere and backward-scattering of blue light from the nanoplate. Spectral analysis was conducted to examine the optical performance of Qc-LEDs with varying combinations and concentrations of nanoscatterers. TiO₂ nanoparticles and Al₂O₃ nanoplates were found to be the best combination for maximal light conversion and extraction efficiency within Qc-LEDs. The results indicate an optimal light efficiency is obtained with the optimal ratio of 1:2:2 for quantum dots, TiO₂ nanoparticles, and Al₂O₃ nanoplates. These findings reveal the relationship between optical properties, morphology, and light conversion efficiency in Qc-LEDs, highlighting the advantages of the hybrid nanoscatterers for improving optical performance of Qc-LEDs.

Investigation of the signal enhancement of Nd³⁺ codoped TeO₂-ZnO pedestal waveguides, at 1064 nm, due to Au nanoparticles deposited over the core is presented for the first time. Nd³⁺ doped TeO₂-ZnO thin film was obtained by RF Magnetron Sputtering deposition. The resulting core with 500 nm height and widths in the 4–40 μm range, exhibited low roughness average in all area measured (0.48 ± 0.04) nm. Minimum propagation losses of 2.2 dB/cm were observed for waveguide width of 40 μm whereas an increase took place for smaller ones. Scanning electron microscopy (SEM) allowed the waveguide structure inspection and transmission electronic microscopy (TEM) the Au nanoparticles evaluation. The results showed that the Au nanoparticles contributed up to 75 % of relative gain enhancement, under 808 nm excitation. This increase was due to the local field growth in the proximity of the nanoparticles that enhances the density of excited Nd³⁺. The internal gain that considers the propagation losses reached positive values for larger core widths (above 8 μm).

The present study opens possibilities for optical amplifiers with low propagation losses based on different metal-dielectric composites, as well as other waveguide-based devices.