Luminescence Intensity Research Articles

Emission behaviour of CdTe/SiO2 core/shell quantum dots in external electric field

Optical properties of CdTe/SiO2 core/shell colloidal quantum dots were investigated in external electric field in the range of 0–140 kV/cm. Maximum of photoluminescence intensity was centered at 2.39 eV with the full width at half maximum of 0.26 eV. It was found that the photoluminescence intensity of quantum dots tends to decrease by 22% and the integrated luminescence intensity tends to decrease by 23% with increasing electric field to the maximum value. However, an increase in the integrated luminescence intensity in the region of 60 kV/cm was observed. We show that both interband and trap-state luminescence is affected by an external electric field with no Stark shift observed. Based on these results, we propose that relaxation of the excited states in CdTe/SiO2 core/shell colloidal quantum dots exposed to an external electric field is affected by two field-dependent mechanisms, i.e. field-induced quenching of luminescence and blocking of charge carrier trapping. The obtained results can be useful to gain better understanding of the electric field effect on the optical properties of CdTe/SiO2 colloidal semiconductor quantum dots and, in particular, on the operation of hybrid organic-inorganic LEDs with emitting layers based on the studied nanocrystals.

How should visual function monitoring be performed and interpreted in surgery for suprasellar tumors?

Preservation of visual function is important in surgery for suprasellar tumors. Visual evoked potentials (VEPs) are expected to play an important role in monitoring visual function during surgery. Given the lack of information in this field, the authors aimed to investigate the effects of optic nerve compression caused by suprasellar tumors to understand the possible usefulness of VEP monitoring using off-response (OFR) VEP. Eleven healthy volunteers who underwent surgery for standard record confirmation and 32 patients with optic chiasm lesions who underwent surgery were examined. Preoperative, postoperative, and intraoperative VEPs were recorded. Propofol anesthesia was administered during intraoperative VEP monitoring. Patients who underwent surgery were monitored using the same stimulation method during surgery. Light stimulation was given from a luminant pad on the eyelids, and low-intensity stimulation with continuous 500-msec emission and 500 msec off was performed. The luminescence intensity of the stimulation was at a maximum of 8000 lx with three attenuation steps, each of which was recorded repeatedly. The OFR potentials and delay latencies decreased as stimulus intensity decreased. In the patient with temporal hemianopia, monocular stimulation produced the highest OFR in the contralateral occipital lobe of the stimulated eye. The authors recorded preoperative, intraoperative, and postoperative VEP in 32 patients and observed intraoperative changes in 23 patients. In the cases where VEP declined during intraoperative recording, it recovered when surgery was discontinued. Furthermore, 3 patients eventually achieved a higher VEP than that achieved at the beginning of the surgery, and rapid recovery was confirmed with visual field examination immediately after surgery. Of the 5 patients in whom VEP did not recover during surgery, 3 showed decreased visual field and acuity after surgery. In 15 cases, potential dropped temporarily but returned to the original potential, and their visual field recovered after surgery. OFR has a diagnostic element in the visual field, in which the maximal potential was recorded on the opposite side of the stimulus with monocular stimulation. Unambiguous determination required stimulation of different intensities in both eyes or 1 eye and multiple recording electrodes placed in the occiput. Monitoring the OFR provides real-time alerts, making it a valuable tool for visual function evaluation in suprasellar surgery.

X-ray excited broadband blue emitting Lu2(1-x)Bi2xO3-PMMA thin films for high resolution imaging

In this paper, cubic-phase Lu2O3:Bi3+ nanoparticles, with a range of sizes between 110 and 180 nm, were obtained by a combination of co-precipitation and thermal annealing techniques. For these nanoparticles upon UV or X-ray excitation, strong broadband emission peaks at 410 and 480 nm corresponding to Bi3+ occupying S6 and C2 (Lu3+(S6) and Lu3+(C2)) sites, respectively, can be observed. On the basis of the concentration-dependent luminescence intensity ratios (I480(C2)/I410(S6)) of Bi3+(C2) to Bi3+(S6), the energy transfer from Bi3+(S6) to Bi3+(C2) can be confirmed at high Bi3+ concentration. In particular, their X-ray absorption coefficient, emission wavelength, afterglow level (60 ppm) and response time (465 ns) are almost comparable to those of the commercial Bi4Ge3O12 crystals. By the means of dispersing Lu1.98Bi0.02O3 nanoscintillators into organic polymer (PMMA)-acetone solution, the Lu1.98Bi0.02O3-PMMA flexible composite films exhibiting rapid response to X-ray photons, high X-ray sensitivity and radiation resistance, good mechanical performance and excellent environmental stability were prepared using a spin-coating technique. On the surface of X-ray imaging screen formed by the flexible dense composite films, the spatial resolution can reach to 6.0 lp/mm at a safe irradiation dose (4.6 μGy). Meanwhile, for the imaging screen using the flexible composite films after bended for thousands of times, we can observe clear image of each reed gap (300 μm) of the music box. For the Lu2O3:Bi3+-PMMA composite films, our results suggest that not only their scintillation properties are almost comparable to those of the commercial broadband Bi4Ge3O12 crystals, but also they might be applied in large-area and non-planar X-ray imaging.

Structural Properties, Energy Interaction, and Applications of CdS Nanomaterial Doped with Rare‐Earth Ions

AbstractSpectroscopic analysis of trivalent praseodymium (Pr+3) and neodymium (Nd+3) ions have received very much interest and reveals good fluorescence efficiency in visible and near IR (NIR) region. Cadmium sulfide (CdS) nanomaterial sample doped with Pr+3 and Nd+3 ions are synthesized at room temperature by simple chemical precipitation method. The synthesized sample has been characterized by powder X‐ray diffraction studies, scanning electron microscopy, transmission electron microscopy, and energy dispersive X‐ray spectra. Absorption spectra of CdS:Nd3+ and CdS:Pr3+ nanoparticles have been recorded at room temperature. Various parameters such as interplanar spacing, micro strain, dislocation density, distortion parameter, and particle size of nanomaterial are computed. TEM and XRD analysis reveal the spherical structure of the CdS:Nd3+ and CdS:Pr3+ nanoparticles in the prepared samples. Energy interaction parameters of the CdS:Nd3+ and CdS:Pr3+ nanoparticles are computed using UV‐visible absorption spectrum. Actually, CdS nanoparticle amplifies the luminescence intensity of Pr+3, Nd+3 ions by up conversion processes. So energy transfer can be observed from CdS nanoparticles doped with Pr+3, Nd+3 ions. Therefore, the use of pump sources and diode lasers in the UV range can be used to excite these samples to work as lasers. CdS:Nd3+ and CdS:Pr3+ nanoparticles find potential application as a window material for hetero‐junction solar cell, light emitting diodes (LED), biological sensors, address decoders, gas detectors, opto‐electronic devices, etc. CdS nanomaterials are also used as pigment in paints and in engineered plastic due to their good thermal stability.

Yb3+/Ho3+ doped Ba3Y2B4O12 phosphors: Upconversion luminescence and temperature sensing properties

Optical thermometry achieved by luminescent materials with good stability and high sensitivity has attracted much attention. In this article, Ba3Y2B4O12, a borate with good chemical stability and high laser threshold was chosen to be host material for preparing a series of Ba3Y2-x-yYbxHoyB4O12 (BYBO:xYb3+/yHo3+; 0.01 ≤ x ≤ 0.35, 0.005 ≤ y ≤ 0.035) upconversion phosphors by a facile solid-state method. Under 980 nm excitation, phosphors show strong 551 nm green emission, weak 668 nm red emission, and 755 nm near-infrared emission, while bright greenlight can be observed by naked eye. When x = 0.15, y = 0.01, luminescent intensity obtains the maximum value. At higher doping concentration, the reduction of cell parameters caused by doping can accelerate the decrease of distance between dopants, so that the energy back transfer process is more likely to occur, weakening the green emission. The intensified non-radiative relaxation results in an increased red emission proportion at higher temperature. According to this rule, the temperature sensing properties based on the fluorescence intensity ratio I668/I551 and I688/I755 are studied. The maximum relative sensitivity (SR) reaches 1.53 % K−1 at 478 K, which is higher than most of reported materials. It shows that BYBO:Yb3+/Ho3+ has application potential in temperature sensing.

Highly sensitive lanthanide complex as a probe for l-kynurenine: A cancer biomarker.

A lanthanide complex based on europium (Eu) and chelidamic acid was synthesized (Eu-CHE) and characterized. The complex Eu-CHE exhibited intense luminescence at 615 nm under excitation at 300 nm and was further investigated for highly sensitive turn-off detection of l-kynurenine (l-kyn), a cancer biomarker. The probe detected l-kyn linearly from 6nM to 0.2μM with a limit of detection and limit of quantification of 1.37 and 4.57 nM, respectively. The probe was investigated for selectivity towards l-kyn among co-existing amino acids and further extended for detecting l-kyn from human serum and urine samples. A low-cost paper strip-based sensing platform was also developed for the visual detection of l-kyn.

Distinguishing xenotime and zircon in ores and estimating the xenotime content for on-site analysis

Estimation of the content of the major minerals containing rare earth element (REE) (e.g., xenotime, monazite, and bastnäsite) to extract metal REEs is a critical task for efficient exploration of mines with REE reserves. X-ray-excited optical luminescence (XEOL) imaging is a promising method for estimating the REE-bearing mineral content on-site. However, distinguishing between xenotime and zircon in ores via XEOL imaging is difficult owing to their similar luminescence colors and intensities. This study reveals that XEOL images of ores before and after annealing at 1300 °C can distinguish xenotime and zircon by investigating images obtained via cathodoluminescence (CL), which is the same phenomenon as XEOL except that it used electron bombardment instead of X-ray irradiation. After annealing, zircon exhibits a luminescence intensity stronger than that of xenotime in the CL images. In these images, zircon corresponds to an area with green luminescence whose CL intensity is drastically enhanced by annealing; in contrast, xenotime corresponds to an area with green luminescence whose CL intensity does not change much. The xenotime content in ores can be estimated from the area corresponding to xenotime in the CL images. The exposure time for CL images, which is comparable to XEOL images, is obtained in 30 s. Therefore, the proposed method can be applied to XEOL imaging and used to on-site prescreen ores before precise quantitative analyses, such as inductively coupled plasma mass spectrometry, electron-probe microanalysis, or scanning electron microscopy based on automated mineralogy, which require a large amount of time; thus, the adoption of the proposed method can lead to a drastic reduction in the time required to explore mines reserving REEs.

Lanthanide-grafted covalent organic framework as a colorimetric and luminescence dual-mode nanoprobe for tetracycline detection

Tetracyclines (TCs) are a group of antibiotics commonly using for infection treatment, however, the leftovers in potable water and food which are derived from the abuse of TCs lead to the adverse human health and environmental impacts. Herein, we developed a lanthanide-grafted covalent organic framework (COF) as a colorimetric and luminescence dual-mode nanoprobe to realize precise, sensitive, rapid, real-time TC determination. Ce3+, Eu3+ ions were chosen to functionalize COFs due to their particular corresponding catalytic and luminescent characteristic for bimodal sensing. COF-Ce-Eu can work as an enzyme mimic to catalytically oxidize the substrate of 3,3′,5,5′-tetramethylbenzidine (TMB) with existence of H2O2, besides, the addition of TC is conducive to promote the pristine catalytic activity as the formation of complexation of COF-Ce-Eu with TC. The catalytic activity and the absorbance of COF-Ce-Eu directly correlate to TC concentration. The ratiometric luminescence response was established on the intensity ratio of the broad band centered at 512 nm originated from the matrix COF and the sharp peak at 616 nm originated from Eu3+. The decrease in luminescence intensity of the peak at 512 nm and the increase at 616 nm depended on TC concentration. This colorimetric and luminescence dual-mode platform exhibits excellent selectivity and sensitivity towards TC, with a wide linear range of 0–50 μM, and low detection limits of 24 nM and 3.4 nM, respectively. The designed bimodal sensing strategy provide a promising double assurance for the accurate trace of TC in food and water samples.

Effects of Tb3+ on properties of luminescent calcium sulfate cement

Calcium sulfate powder materials containing terbium ions at 0, 1.0, or 2.0 mol.% were obtained. They are characterized by the presence of a CaSO4 × 0.5H2O phase, while Tb3+ is incorporated into the lattice at ≤1.0 mol.%. Specific surface area enlarged from 2.1 to 22.5 m2/g as crystallite size decreased from 68 to 31 nm. Thermal analysis showed that terbium slightly raises the temperature of CaSO4 × 2H2O-to-CaSO4 transition. Studies of solubility in SBF solution showed the presence of a calcium phosphate layer in terbium-containing cements on the 7th day. Luminescent properties were studied by excitation at 266 nm and 489 nm corresponding to absorption bands of the host and Tb3+ (7F6 - 5D4 absorption band). The recorded emission peaks of the materials showed that the luminescence of the samples was green, with the luminescence intensity increasing when Tb3+ was introduced. The developed materials can find applications in medicine as bioimplants with a possibility of noninvasive visualization of the bone restoration process.

Synthesis and Properties of Eu and Ni Co-Doped ZnS Nanoparticles for the Detection of Ammonia Gas

Zinc sulfide nanoparticles were synthesized successfully via chemical co-precipitation, both in undoped form and co-doped with Europium (Eu) and Nickel (Ni). All prepared samples exhibited cubic zinc blende structure as confirmed by X-ray diffraction (XRD). The average particle size ranged from 3 to 6 nm for both pure and (Eu, Ni) co-doped ZnS, with no alteration in the crystal structure due to Eu and Ni co-doping. However, increasing the Ni dopant concentration (0, 2, 4, & 6 at%) while maintaining a constant Eu concentration (4 at%) led to an enhancement in the crystallite size. This was further validated by transmission electron microscopy (TEM), which showed particle sizes consistent with the XRD findings (3–5 nm). Microscopic analysis via scanning electron microscopy and TEM revealed spherical agglomerated morphology for the (Eu, Ni) co-doped nanoparticles. Energy-dispersive X-ray spectroscopy spectra confirmed the stoichiometric chemical composition of ZnS: Eu, Ni. Photoluminescence studies demonstrated an increased intensity of green luminescence at 6 at% Ni co-dopant concentration. Moreover, the synthesized samples exhibited promising gas sensing properties, particularly towards ammonia gas, with good selectivity. Notably, both pure and (Eu, Ni) co-doped ZnS nanoparticles showed rapid response and recovery times at room temperature, suggesting their potential applicability in gas sensing applications.

Electrochemiluminescent properties of carbon nitride nanoflowers and their application to the detection of melatonin in foods

Carbon nitride nanoflower materials (CNNFs) modified electrodes were prepared and used as electrochemiluminescence (ECL) sensors for the sensitive detection of melatonin (MT) in food. The luminescence intensity of CNNFs is increased by 4.6 times compared with bulk g-C3N4. In addition, the effect of dissolved oxygen on the material was eliminated, and the stability of ECL intensity of CNNFs was improved. Under the optimal experimental conditions, there is a good linear relationship between the ECL intensity ratio and logCMT in a concentration range of 2.0 × 10−11–1.0 × 10−6 mol/L, and the detection limit is 6.2 × 10−13 mol/L. This experiment has been successfully used for the detection of MT in rice, black rice, oats, apples, bananas, grapes, carrots, tomatoes, cucumbers, bread, and beers. The results are consistent with those obtained by high-performance liquid chromatography (HPLC). Therefore, this sensor is a sensitive and effective method for detecting MT content in food.

Growth of ultimate high-density scintillating films for high-resolution X-ray imaging at synchrotrons

Scintillators are X-ray to visible light converters applied in X-ray imaging detectors used at synchrotrons. Drastically improved performances of the 4th generation synchrotron sources enable us to perform X-ray imaging experiments at higher energies. For high spatial resolution X-ray imaging (micrometer to submicrometer), thin scintillating films are required. Consequently, especially for high X-ray energies (30keV to 100keV), the detection efficiency is limited due to the low X-ray absorption efficiency of the thin films. We have used Liquid Phase Epitaxy (LPE) to grow thin films of one of the ultimate high-density materials, Lu2Hf2O7:Eu3+, which demonstrate scintillating properties and thus combine high spatial resolution and maximized absorption efficiency. X-ray imaging experiments demonstrate that the Modulation Transfer Function (MTF) reaches 10% at 900 lp/mm, and radiographs visually confirm the promising imaging properties. We present structural, luminescent, and scintillation characterization of Lu2Hf2O7:Eu thin films grown on ZrO2:Y substrates, showing that the films crystallize in the disordered fluorite structure and the europium ions incorporate into the structure and enhance the luminescence intensity. This contribution is a first step toward developing promising ultra-dense, hafnate-based scintillating screens for high spatial resolution X-ray imaging.

Eu2+ doping and Mg2+-coupled Zn2+, Ca2+ and Sr2+ cations induce tunable orange-blue luminescence in cordierite

A series of Mg2Al4Si5O18:xEu2+ (x = 0.2, 0.6, 1.4, 2.8, 6.0mol‰) and Mg2Al4Si5O18:0.05B, 1.4Eu2+ (BZn2+, Ca2+ and Sr2+) phosphors were prepared by high-temperature melt ice-water quenching and heat treatment. In this study, using Eu2+ ions as a structural probe, we investigated the effects of heat treatment temperature, Eu2+ ion concentration, and cation position on the crystal phase and local structure, triggering changes in the luminescent properties of the phosphor and achieving coordinated blue and red luminescence. Through heat treatment analysis, we proposed the formation process of the two phases of cordierite. The doping of different concentrations of Eu ions in cordierite triggers the phase transition of the host lattice. The molar distribution ratio of Eu2+ ions was calculated by Gaussian peak-splitting fitting to identify the detailed occupancy distribution of the Eu2+ ions in μ-cordierite and α-cordierite. In the α-cordierite phase, with the doping of Zn2+, Ca2+, and Sr2+ cationic sites, the PL is modulated from orange to blue emission based on the selective occupancy of Eu2+ ions, which is caused by the difference in cationic radii and structural distortion. The comprehensive luminescence intensity of MASE1.4, MASZ0.05E1.4, MASC0.05E1.4, and MASS0.05E1.4 phosphors were 81.18%, 83.49%, 62.67%, and 76.41% at 150 °C compared to that at 30 °C, indicating the better thermal stability of the prepared phosphors. The luminescence tunable strategy by cation and Eu2+ doping simultaneously modifies the emission and achieves different thermal stability, providing a new design concept for the development of Eu2+-doped silicate phosphors.

Dual substitution of host lattice ions to enhance the luminescence properties of Zn2TiO4:Cr3+ phosphor.

Near-infrared light sources have potential applications in many fields. Cr3+ is a good luminescence centre to prepare near-infrared phosphors. Improving the performance of existing near-infrared luminescent materials has indeed attracted great interest from researchers. The luminescence properties of Zn2TiO4:Cr3+ were improved by crystal field engineering strategies. Zn2+-Ti4+ was partially replaced using a Li+-Nb5+ ion pair based on the Zn2TiO4:Cr3+ phosphors. Luminescence Cr3+-activated luminescent materials are sensitive to changes in the local crystal structure and crystal field environment. Doping of Li+-Nb5+ increased the luminescence intensity up to 2.7 times that of the undoped sample. Also, the thermal stability of the phosphor was greatly increased by the replacement of Li+-Nb5+.

Carbon dots encapsulated in (YGd)2O3:Eu3+ nanophosphors for thermal sensing, advanced forensic and information security applications

The outstanding optical characteristics of carbon dots (CDs) make them an extremely promising class of multifunctional nanomaterials based on carbon. The incorporation of hydrothermally prepared Aloe vera carbon dots (AVCDs) into europium doped yttrium gadolinium ((YGd)2O3:Eu3+) mixed oxide nanophosphors ((YGO):Eu3+ NPs) synthesized through the solution combustion (SC) method. The resulting (YGO):Eu3+@AVCDs nanocomposite (NCs) demonstrates a broad excitation band, with the intense peak at ∼395 nm, aligning with the emission wavelength (350–420 nm) of n-UV LED chips. Notably, the (YGO):Eu3+@AVCDs (5 wt %) NCs exhibits a 4 fold increase in photoluminescence (PL) intensity compared to (YGO):7Eu3+, attributed to the fluorescence resonance energy transfer (FRET) between AVCDs and Eu3+ ions. Remarkably, even at an elevated temperature of 423 K, the thermal stability of (YGO):Eu3+@AVCDs (5 wt %) remains exceptional, retaining 88.31 % of its initial luminescence intensity. The internal quantum efficiency (IQE) is measured at a notable 74.16 %, while the optimized composite achieves a remarkable color purity of 99.59 %. Latent fingerprints (LFPs) are effectively developed on different surfaces using the optimized NCs via a simple powder dusting technique, and these fingerprints (FPs) revealed under 365 nm UV light. The study also examines various pore parameter namely size, shape, number, position, type, and inter-distance. Moreover, a transparent anti-counterfeiting (AC) ink is fabricated using optimized NCs providing effective AC features through its red emission under 365 nm UV light. This study not only offers solutions for overcoming the self-quenching effect of CDs but also underscores the potential applications in white light emitting diodes (w-LEDs), latent fingerprints, lip prints (LPs), and anti-counterfeiting.

Physical and luminescence properties of Ce3+ activated strontium phosphate glasses

Strontium phosphate (SrO–P2O5–Al2O3–Gd2O3) glasses with 0.05, 0.1, 0.5, and 1 mol % CeO2 were prepared by the conventional melt quenching technique. These glasses' luminescence, scintillation, and physical properties were measured and discussed in detail. The density, refractive index, and oxygen packing density of the studied glasses were increased with an increase in CeO2 concentration. At lower concentrations of CeO2, the characteristic 310 nm emission from Gd3+ and broadband emission from Ce3+ ions were obtained under X-ray excitations. The intensity of both Gd3+ and Ce3+ emission bands under 270 nm Gd3+ excitations reduced with further increase in CeO2, showing the delayed energy transfer from Gd3+ to Ce3+ ions. The integrated X-ray-induced luminescence intensity of 0.5% CeO2 glass was found to be 21% that of reference BGO crystal. For the lower concentration of CeO2, a slow decay time along with the fast Ce3+ decay was observed and disappears for higher CeO2 concentrations. The fast luminescence decay in the range of 22 ns–30 ns was observed for all the PSAG:Ce glasses, which was attributed to the lifetime of the 4f-5d transition of the Ce3+ ions. The faster decay time and reasonable scintillation light suggest the application of these glasses for radiation detector applications.

Achieving Efficient Optical Thermometry in Terbium‐Doped Highly Transparent Ceramics

AbstractTemperature‐responsive dynamics of excited‐state population in terbium (Tb) ions may open the door for the advancement of high‐performance photothermal feedback windows. However, obtaining robust luminescence and superior transparency in Tb‐doped ceramics continues to pose a formidable challenge, leaving them far away from photonic application. Here, to fill this important gap, the demonstration of Tb doped transparent ceramics for luminescent thermometric windows is reported. Y2Zr2O7:Tb (YZO:Tb) ceramics are used as an illustrative example. After a sequence of thermal treatments, the defect centers F/F+ and defect clusters [] and [] in these YZO:Tb transparent ceramics are eliminated, resulting in a notable enhancement of their in‐line transmittance from 71% to 76%, making it close to the theoretical limit. Moreover, the corresponding photoluminescence increased significantly, reaching a factor of 296 times. Furthermore, a temperature feedback window is designed using the excitation intensity ratio (EIR) or single‐band luminescence intensity ratio (SBLIR) mode, which presents high sensitivity (1.04%) and high repeatability (98%). This work not only provides a paradigm in the application of the Tb doped transparent ceramics for temperature sensing windows, but also suggests a pathway to build efficient thermometers based on excited state population deployment in window systems.

Exploring the Gamma-Ray Enhanced NIR-Luminescence and Cytotoxic Potential of Lanthanide-Naphthalene Dicarboxylate based Metal-Organic Frameworks.

In this investigation, we explore the integration of lanthanides into Metal-Organic Frameworks (MOFs) to enable Near-Infrared (NIR) emission. Specifically, we focus on Lanthanide-Naphthalene Dicarboxylate based MOFs (Ln-MOFs), incorporating elements such as Praseodymium (Pr), Samarium (Sm), Dysprosium (Dy), and Erbium (Er). The synthesis of Ln-MOFs is achieved via the hydrothermal method. The structure, morphology, thermal stability, and luminescence properties of synthesized Ln-MOFs have been evaluated through different characterization techniques. Upon photoexcitation at 350nm, Ln-MOFs show the emission in the Visible and NIR region. Further, the luminescence intensity of Ln-MOFs enhanced by 2-3 folds in the visible region and 6-8 folds in NIR region after exposing to Gamma irradiation at 150kGy. Cytotoxic effect on the viability of MDA-MB 231 and MDA-MB 468 Triple negative breast cancer (TNBC) cells was evaluated by MTT assay. The results revealed that among all synthesized MOFs, Pr-MOF exhibited an aggressive cytotoxic effect. Additionally, analysis of phase-contrast microscopy data indicates that Pr-MOF induces alterations in the morphology of both MDA-MB 231 and MDA-MB 468 TNBC cells when compared to untreated controls. The findings in this study reveal the utilization of Ln-MOFs for studying cytotoxicity and highlight their ability to enhance near-infrared (NIR) emission when exposed to gamma radiation.

Expanding near-infrared emission bandwidth in K2NaCrF6:Fe3+ phosphors through dipole-dipole energy transfer

Currently, the application potential of Cr3+ doped near-infrared (NIR) fluoride phosphors excited by blue light is promising. However, the development of near-infrared fluoride phosphors with wider emission bandwidth remains a challenge. Herein, we employed the hydrothermal method to prepare K2NaCrF6:Fe3+ phosphors. Upon excitation at 432 nm, the K2NaCrF6:xFe3+ phosphors exhibited broad near-infrared emission, with the main peak ranging from 752 nm to 780 nm. As the Fe3+ concentration increased, the luminescence intensity of the K2NaCrF6:xFe3+ phosphor decreased, accompanied by a redshift in the emission band and an increase in the full width of the emission spectrum half-peak. These changes can be attributed to the dipole-dipole interaction, specifically the energy transfer between Fe3+ and Cr3+, leading to the 4T2(4F) → 4A2(Cr3+) and 4T1(4G) → 6A1(6S) (Fe3+) transitions.

Investigating the use of Er3+ doped β-Ca2SiO4 phosphors derived from agricultural waste for thermal sensing and forensic applications

Leveraging agricultural waste, Erbium (Er3+) doped β-Ca2SiO4 phosphors (β-CS:Er3+) with concentrations ranging from 1 to 9 mol % were developed using the solid-state reaction method. These β-CS:Er3+ samples underwent extensive characterization to examine their crystalline structure, surface morphology, photoluminescence (PL) properties, and thermal sensing capabilities. The PL emission, excited at 378 nm, prominently displayed a peak at 549 nm, indicative of the green emission primarily due to the 4S3/2 → 4I15/2 transition. An optimal concentration of Er3+ at 5 mol% (β-CS:5Er3+) is identified, showing peak luminescence intensity, whereas, higher concentrations led to a decrease in intensity because of concentration quenching (CQ) effects. Temperature-dependent photoluminescence (TDPL) analysis revealed an increase in emission intensity at 523 nm, while the peak at 549 nm exhibited a decrease in intensity within the temperature range of 303–463 K. Nevertheless, the emission peak at 549 nm demonstrates remarkable thermal stability at elevated temperatures, maintaining 79.32% of its emission intensity at 423 K. The optimized β-CS:5Er3+ phosphor exhibited its chromaticity coordinates (0.3152, 0.6631) in the green region under 378 nm excitation, alongside promising temperature sensing capabilities with a relative sensitivity of 2.80 % K−1. The application of these phosphors in a powder dusting technique for revealing latent fingerprints (LFPs) and latent lip prints (LLPs) under 365 nm UV light uncovered detailed ridge and groove patterns on various substrates. This approach, highlighting the phosphor's exceptional fluorescence, dual adherence, and non-interfering background, showcased its potential for enhanced forensic analysis. The thorough examination of LFPs and LPs under various conditions, including aging, heat, and UV exposure, confirms the β-CS:Er3+ NPs' suitability for cutting-edge display technologies and forensic methodologies.