Luminescence最新文献

A rapid and highly sensitive first derivative synchronous fluorescence spectrometry with double scans was successfully optimized for the simultaneous determination of dissolved phenanthrene (Phe), 1-methylphenanthrene (1-MP), and 3-methylphenanthrene (3-MP) and their metabolites such as 1-hydroxy-2-naphthoic acid (1H2NA) and salicylic acid (SA) in the biodegradation processes of Phe, 1-MP, and 3-MP by Novosphingobium pentaromativorans US6-1. Δλ of 55 and 109 nm were selected for Phe, 1-MP, 3-MP, 1H2NA, and SA, respectively. The intensities of the first derivative synchronous fluorescence detected at λex of 289, 292, 291, 354, and 312 nm for Phe, 1-MP, 3-MP, 1H2NA, and SA varied linearly with the concentrations of them in the ranges of 0.20 × 10⁻⁷–44.89 × 10⁻⁷, 0.20 × 10⁻⁷–13.04 × 10⁻⁷, 0.20 × 10⁻⁷–13.04 × 10⁻⁷, 0.22 × 10⁻⁷–76.30 × 10⁻⁷, and 0.11 × 10⁻⁷–52.00 × 10⁻⁷ mol/L. The limits of detection were 0.11 × 10⁻⁹, 0.30 × 10⁻⁹, 0.27 × 10⁻⁹, 0.33 × 10⁻⁹, and 2.90 × 10⁻⁹ mol/L for Phe, 1-MP, 3-MP, 1H2NA, and SA, respectively, with RSD less than 2%. The method was successfully applied in situ to detect the instantaneous concentrations of the PAHs and their metabolites, especially SA, during their biodegradation processes under simulated conditions in the lab. The results demonstrated that the upper metabolic pathways of 1-MP and 3-MP by US6-1 were distinctly different from that of Phe owing to steric hindrance of the methyl group.

Er³⁺ and Er³⁺/Yb³⁺-doped phosphate-based glasses have been synthesized by melt quenching technique and are characterized by absorption spectra, infrared emission, decay curves, Fourier transform infrared spectrum and up-conversion studies. From the absorption spectra, intensity parameters and radiative properties have been derived utilizing the Judd–Ofelt theory. Er³⁺-doped glass is found to have larger radiative lifetime for the laser originating from ⁴I_13/2 level at 1537 nm. Infrared and visible characteristic emissions have been measured by exciting at 790 nm through down- and up-conversion, respectively. The up-conversion spectra consist of intense green emission at around 525 and 545 nm ascribed to the ²H_11/2 → ⁴I_15/2 and ⁴S_3/2 → ⁴I_15/2 transitions, respectively, and a weak red emission at around 656 nm due to the ⁴F_9/2 → ⁴I_15/2 transition of Er³⁺ ions. Various spectroscopic and laser characteristics of these glasses have been calculated and compared with those of similar reported ones.

The present study focused on extracting the anthocyanin dyes in ethanol, acidic ethanol, methanol, and acidic methanol solvents from Nerium oleander flowers by a simple maceration extraction process. FTIR spectroscopy and vibrational studies have confirmed the existence of polyphenolic groups in 2-phenyl chromenylium (anthocyanin) dyes. The optoelectronic results show the least direct bandgap (2.89 eV), indirect bandgap (1.98 eV), Urbach energy (0.120 eV), high refractive index (1.654), dielectric constant (3.294) and high optical conductivity (1.813 10³ S/m) for the anthocyanin dye extracted found in acidic ethanol solvent. The photoluminescence properties such as Stokes' shift, quantum yield, and lifetime results show that anthocyanin dyes are promising candidates for red-LEDs and optical materials. The excellent correspondence between the absorption and emission spectra reinforces that the anthocyanins are efficient (89%) FRET probes. Further, the donor and acceptor undergo redshift in excitation and emission spectra in all studied solvents. The photometric properties such as CIE, CRI, CCT and color purity results of anthocyanins in all studied solvents revealed that this material exhibits pink to red shades (x = 0.40 → 0.50 and y = 0.46 → 0.39) and is well suitable for have great potential in the manufacturing of Organic-LEDs and other optoelectronic device applications.

Glasses from the system Na₂O-Al₂O₃-SiO₂-B₂O₃-Dy₂O₃ are prepared with three different concentrations of the Dy³⁺ ion—0.5, 1, and 2 at%. Glass-ceramics are obtained after thermal treatment of the parent glass at 580°С and 630°С during 2, 5, and 24 h. The crystallizing phases, the crystallinity degree, and the nano crystalline size are determined. The crystallizing phases after thermal treatment are NaAlSiO₄ in two different modifications and Na₃B₃O₆. XRD analyses show the presence of third unknown phase in some samples. Emission and excitation spectra of the glass-ceramics show the characteristic peaks of Dy³⁺ (⁴F_9/2 → ⁶H_15/2, ⁴F_9/2 → ⁶H_13/2 and ⁴F_9/2 → ⁶H_11/2 at 483, 575, and 668 nm, respectively). The yellow peak is dominating in all samples. The spectra show different intensity depending on the Dy³⁺ concentration, temperature, and time of the thermal treatment. This result suggests that the emission color can be controlled by these three factors.

The objective of this study was to synthesize strontium titanate (Sr_1-xCe_xTiO₃) doped with Ce³⁺ by solid state method. Its crystalline structure is Sr_1-xCe_xTiO₃, and its bandgap ranges from ~3.3 to ~2.7 eV. In the photoluminescence of samples excited at 288 nm, the maximum emission of blue light was observed at 380 and 390 nm. Photocatalytic results show that dye molecules have a high absorbance, whereas their surface area is large. According to a line sweep voltammetric plot (LSV), illumination increases the current density by 0.4 μA cm⁻² compared with dark conditions. It was demonstrated that the material changed from n-type to p-type under doping. Chronoamperometry spectra were obtained for sample Sr_1-xCe_xTiO₃ (x = 0, 0.005, 0.01, 0.03, 0.05) when an electrical voltage of 0.8 V was applied versus NHE. The plots indicate an increase in the current density under “light ON” conditions and a decrease under “light OFF” conditions. As Ce³⁺ concentration increases, the photocurrent increases until about 3 mol%, after which it decreases abruptly.

Eu³⁺-activated phosphors with distinct photoluminescence properties are well-suited for diverse applications, including lighting, sensing, and imaging. Despite their potential, the large-scale and energy-efficient production of Eu³⁺-doped phosphors remains a significant challenge for industrial applications. This research delves into the luminescent performance of Eu³⁺ ions in nitrate solutions at room temperature by employing detailed spectroscopic characterization. Results reveal vibrant red luminescence at 594 nm and 616 nm in europium nitrate solutions, irrespective of concentration or solvent. We proposed a luminescent mechanism based on the formation of coordination complexes in nitrate solution. Furthermore, the investigation highlights the superior performance of NH₂- over CH₂-ligands in mitigating the deactivation of Eu³⁺ emissive state induced by OH⁻ oscillators in H₂O solvent, leading to enhanced photoluminescence. Particularly, europium nitrate solutions without lengthy preparation exhibit ligand-dependent luminescent feature, showcasing potential applications in anti-counterfeiting and coordination group structure detection. This study here not only enhances our understanding of rare earth luminescence mechanisms, but also broadens the range of rare earth luminescent materials.

Hydrogen and renewable fuels were generated using cost-effective and efficient electrocatalysts for water splitting. In this work, a CuO-based photocathode is used for the water splitting to generate hydrogen energy by PVD technique. The XRD analysis reveals the deposition of CuO thin film on ITO substrates, which is monoclinic. The XRD and LSV analysis of CuO confirmed the type of semiconductor and observed to be P-type semiconductor. SEM study of CuO confirmed the shape, morphology to be a circular and regular shape. The grain size of deposited CuO thin film was found to be 18 nm. The absorption and transmission of CuO thin film were observed through UV spectroscopy analysis and were found to be better photocatalyst in visible range 415–425 nm. The transmittance of the prepared thin film was noted to be maximum 7.6% in the UV range (280–300 nm). The band gap was also measured employing the Tauc plot and found to be 2.98 eV, which is most favorable for water splitting application. FTIR study showed the stretching, vibration, and the functional group of the deposited CuO thin film; the broad band of stretching of Cu-O in monoclinic CuO was observed at the range of 500–700 cm⁻¹, and further peaks were also noted at the range of 1500–1600 cm⁻¹. The linear sweep voltammetry (LSV) of CuO thin film was calculated in the absence of solar spectra and the presence of solar spectra and observed to be enhanced in current under solar spectra. The solar light to hydrogen emission percentage (STH %) of CuO through LSV was observed to be 2.04% under solar spectra. The low Nyquist curve of blank ITO and CuO-coated ITO substrate via electrochemical impedance spectroscopy (EIS) analysis was observed, which confirmed the enhancement of EIS of CuO-coated ITO. The hydrogen generation rate was also calculated by electrochemical cell and observed to be 5325.21 mol g⁻¹ for 6 h.

This study focuses on developing novel antimicrobials to combat drug-resistant pathogens, addressing compounds failing clinical trials due to inadequate physicochemical properties. Sixteen imidazolidine-4-one derivatives were synthesized by extensive evaluation using molecular docking, absorption, distribution, metabolism, excretion (ADME) predictions, and antimicrobial testing. Molecular docking studies conducted with Schrödinger's Glide revealed that compounds S4 and G8 exhibited superior docking scores of −7.839 and −7.776, respectively. The G series outperformed the S series in scores. ADME analysis confirmed all compounds adhered to Lipinski's rule of five. In addition, IR and NMR provided details about the structure of the compounds. Antimicrobial activity was assessed against Escherichia coli, Staphylococcus aureus, and Candida albicans, with compounds G2 and S2 showing exceptional minimum inhibitory concentration (MIC) values of 6.25 μg/mL against E. coli. S2 also demonstrated impressive activity against S. aureus (MIC 3.12 μg/mL), and S4 exhibited potent activity against C. albicans (MIC 0.8 μg/mL) than fluconazole (1.6 μg/mL). Additionally, antihelmintic activity was evaluated, with G1, G3, G8, S2, S4, S7, and S8 showing effective paralysis and death time 20 min and below at 50 mg/mL concentration. These results underscore the potential of new imidazolidine-4-one derivatives as suitable sources to develop a drug candidate to treat resistant infections.