Decay Time Measurements Research Articles

Luminescence Properties of M(AlCl4)2:Yb2+ (M = Ca, Sr, Ba): Ideal Materials for the Investigation of Structure–Luminescence Relationships

In this work, the chloride system M(AlCl4)2 (M = Ca, Sr, Ba) doped with Yb2+ is investigated in greater detail. The influence of the [AlCl4]− ion on the position of the emission band of Yb2+ is investigated and the emission spectra are recorded. The emission spectra of the Yb2+-doped materials are characterized by broad 4f135d1 (HS) ↔ 4f14 transitions with maxima in the range between 416 nm (Ca) and 421 nm (Ba) (24,061–23,738 cm−1), whereas the Ba compound features an additional 4f135d1 (LS) ↔ 4f14 emission band at 397 nm (25,203 cm−1) at lower temperatures. The unusual reverse order of the positions of the emission maxima (Ba < Sr < Ca) most probably indicates an influence of the local symmetry on the location of the emission bands. Temperature-dependent emission and decay time measurements reveal strong thermal quenching processes, which gives additional insight into the mechanistic properties of the luminescence. An investigation of the decay times for all transitions reveals generally shorter values compared to values found in the literature, which was likely caused by the strong thermal quenching.

Effective Steady‐State Recombination Decay Times in Comparison to Time‐Resolved Photoluminescence Decay Times in Halide Perovskite Solar Cells

One of the key topics in perovskite solar cells is the reduction of charge carrier recombination, with the aim of increasing power conversion efficiency. The recombination lifetime is a commonly used tool, as it directly affects the current–voltage curve via the diffusion length. The lifetime is often estimated using time‐domain measurement methods such as time‐resolved photoluminescence. However, two obstacles emerge when applying the transiently measured decay times to the steady‐state theory. In general, the decay time depends on the charge carrier concentration, and it is often not clear under which conditions the transient measurement must be conducted to be comparable with the steady‐state performance of the device. Furthermore, diffusion and capacitive effects due to charge injection and extraction can influence transient techniques and cause the measured decay time to deviate from the sought‐after recombination lifetime. Voltage‐dependent steady‐state photoluminescence measurements can be used to estimate the internal voltage during device operation and allow the extraction of collection efficiencies and effective steady‐state decay times that are independent of transport and capacitive effects. Here, the differences between the steady‐state and transient decay times are identified and discussed, and the losses in the current–voltage curve caused by extraction issues are quantified.

Synthesis and Upconversion Luminescence Fine-tuning of Yb3+/Ho3+-Doped Indium and Gallium Oxide Nanoparticles.

Rare earth (RE) dopants can modulate the bandgap of oxides of indium and gallium and provide extra upconversion luminescence (UCL) abilities. However, relevant UCL fine-tuning strategies and energy mechanisms have been less studied. In this research, InGaO, Ho3+ monodoped and Yb3+/Ho3+ codoped In2O3, and Ho3+ monodoped Yb3Ga5O12 nanoparticles (NPs) were synthesized by a solvothermal method. The effects of Yb3+ and Ho3+ dopants on the crystal structures, UCL properties, and optical bandgaps of the oxides were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), UCL spectroscopy, and measurements of decay times, pump power dependence, and transmittance spectra. The crystal structures of oxide products of indium and gallium were significantly modified with RE dopants. In2O3 and Yb3Ga5O12 were selected as the host materials. For Yb3+/Ho3+ codoped In2O3 NPs, there existed energy transfers from the defect states of In2O3 to Ho3+ and from Yb3+ to Ho3+. With a fixed Ho3+ concentration, In2O3:0%Yb3+,2%Ho3+ NPs showed the optimal UCL properties mainly due to In2O3-Ho3+ energy transfer and Ho3+-Yb3+ energy-back-transfer, while with a fixed Yb3+ concentration, In2O3:5%Yb3+,3%Ho3+ NPs with a slight Yb2O3 impurity and Yb3Ga5O12:2%Ho3+ NPs did mainly due to Ho3+-Ho3+ cross-relaxation. Besides, the optical bandgaps of In2O3 and Yb3Ga5O12 were noticeably broadened with RE dopants. These findings can offer feasible directions for the synthesis and UCL fine-tuning of RE-doped oxides of indium and gallium and improve their multifunction application prospects in the fields of semiconductor and UCL nanomaterials.

Development of a fully automated workstation for conducting routine SABRE hyperpolarization

SABRE is emerging as a fast, simple and low-cost hyperpolarization method because of its ability to regenerate enhanced NMR signals. Generally, SABRE hyperpolarization has been performed predominantly manually, leading to variations in reproducibility and efficiency. Recent advances in SABRE include the development of automated shuttling systems to address previous inconsistencies. However, the operational complexity of such systems and the challenges of integration with existing workflows hinder their widespread adoption. This work presents a fully automated lab workstation based on a benchtop NMR spectrometer, specifically designed to facilitate SABRE of different nuclei across different polarization fields. We demonstrated the capability of this system through a series of routine SABRE experimental protocols, including consecutive SABRE hyperpolarization with high reproducibility (average standard deviation of 1.03%), optimization polarization of 13C nuclei respect to the polarization transfer field, and measurement of polarization buildup rate or decay time across a wide range of magnetic fields. Furthermore, we have iteratively optimized the durations for pulsed SABRE-SHEATH 13C pyruvate. The constructed SABRE workstation offers full automation, high reproducibility, and functional diversification, making it a practical tool for conducting routine SABRE hyperpolarization experiments. It provides a robust platform for high-throughput and reliable SABRE and X-SABRE hyperpolarization studies.

Exploring the structural, photophysical, and electrical properties of Dopant-Free hole transporting material based on 2, 7-carbazole from experimental to simulation

This paper presents the development of a dopant-free HTM as a thin film, utilizing carbazole (2,7) as a central building block. The deposition of homogeneous thin films of HTM2 was successfully achieved through Physical Vapor Deposition. The morphological, optical, and electrical properties of the fabricated samples were extensively studied using techniques such as Atomic Force Microscopy (AFM), Scanning Electron Microscopy (SEM), UV–visible spectroscopy, and Photoluminescence Technique. The AFM and SEM analyses demonstrated the uniformity and flatness of the thin film surfaces. The UV spectra results indicated that the maximum absorption spectra did not exhibit significant shifts when measured in chlorobenzene solvent, with an estimated band gap of approximately 2.96 eV. Photoluminescence spectroscopy and decay time measurements were conducted on HTM2 thin films, which revealed emission in the green-yellow region. The photoluminescence spectra of the thin films exhibited red-shifted emission bands compared to the solution, attributable to stronger π-π intermolecular interactions resulting in the closeness of the molecules in the solid state. This work finally couples the theoretical and experimental results to validate our obtained results and to get an idea about the efficiency of the cell-based HTM2. The obtained results confirmed that the investigated material can find applications in perovskite solar cells.

Tunable emission color of novel Y3NbO7:xDy3+ phosphor

Powders of Y3NbO7:xDy3+ (x = 0.5, 1, 1.5, 3 and 5 mol%) were produced through a solid-state process. X-ray diffraction investigations confirm the fluorite-type structure (space group 𝐹𝑚3̅𝑚) of powders with crystallite size in the range of 19–60 nm. Both the photoluminescence excitation and emission spectra revealed the presence of defects within the material. With different excitation wavelengths, the emission spectra exhibited distinct emission patterns. At each excitation wavelength, the emission was quenched at Dy3+ concentration higher than 1 mol%. The decay time measurements of the highest intensity emission revealed a progressive decrease from 0.472 milliseconds for x = 0.5 mol% to 0.246 milliseconds for x = 5 mol%. The CIE chromaticity coordinates investigation revealed that the emission color may be altered by varying the excitation wavelength, ranging from blue (excitation at 333 nm) and near-white (excitation at 353 nm and 390 nm) to orange (excitation at 457 nm). The chromaticity of emission under 353 nm and 390 nm excitation validated the material's suitability as an almost-white phosphor.

Estimation of sound absorption coefficient at modal frequencies using decay time measurements and eigenvalue model in a small room

Measuring the sound absorption coefficient in a small reverberation room below the Schroeder frequency is a challenging task and the results are subject to a high degree of uncertainty. Recent research shows that the low-frequency acoustic properties of the enclosure and the test sample should be characterized by quantities that describe the modal sound field. The aim of this paper is to present a method for estimating the absorption coefficient of a test sample at modal frequencies in the low frequency range and to demonstrate its applicability in a small room. The hybrid inverse approach is based on eigenvalue measurement data coupled with a finite element model to estimate the sound-absorbing properties of a small room and the test sample. The method was tested experimentally and the results were consistent with those of the long impedance tube method. The applicability of the proposed method was further demonstrated by the in-situ characterization of different acoustic samples in the low frequency range.

Origin of discrete donor–acceptor pair transitions in 2D Ruddlesden–Popper perovskites

Two-dimensional (2D) van der Waals nanomaterials have attracted considerable attention for potential use in photonic and light–matter applications at the nanoscale. Thanks to their excitonic properties, 2D perovskites are also promising active materials to be included in devices working at room temperature. In this work, we study the presence of very narrow and spatially localized optical transitions in 2D lead halide perovskites by μ-photoluminescence and time-decay measurements. These discrete optical transitions are characterized by sub-millielectronvolt linewidths (≃120μeV) and long decay times (5–8 ns). X-ray photoemission and density-functional theory calculations have been employed to investigate the chemical origin of electronic states responsible of these transitions. The association of phenethylammonium with methylammonium cations into 2D Ruddlesden–Popper perovskites, (PEA)2(MA)n−1PbnI3n+1, particularly in phases with n≥2, has been identified as a mechanism of donor–acceptor pair (DAP) formation, corresponding to the displacement of lead atoms and their replacement by methylammonium. Ionized DAP recombination is identified as the most likely physical source of the observed discrete optical emission lines. The analysis of the experimental data with a simple model, which evaluates the Coulombic interaction between ionized acceptors and donors, returns a donor in Bohr radius of the order of ≃10 nm. The analysis of the spectral and electronic characteristics of these single donor–acceptor states in 2D perovskites is of particular importance both from the point of view of fundamental research, as well as to be able to link the emission of these states with new optoelectronic applications that require long-range optically controllable interactions.

Nano-second life time decay and Z-scan measurement: A tool to investigate the relevance of excited state dynamics with non-linear optical parameters in cis substituted Wells-Dawson POM-Porphyrin hybrids

Materials possessing non-linear optical NLO responses have gained considerable attention in the field of photonics because they have the potential to produce new frequencies when they interact with intense light by means of non-linear interactions. Synthesizing NLO materials based on porphyrin covalently bonded with polyoxometalates (POMs) is complicated and rigorous, requiring special techniques in order to get pure compounds with a higher yield. Here, we study the third-order NLO parameters along with the fluorescence lifetime decay values in a nanosecond(ns) time span for WDPOMCis2PyP and WDPOMCis2PhP (bearing the Wells-Dawson POM at the cis position) and their porphyrin precursors Cis2PyPTris and Cis2PhPTris, respectively. A comparison of third-order NLO characteristics with fluorescence lifetime decay data indicates that an increase in NLO properties has been observed with shorter lifetime decay values and vice versa. From the results, it is clear that WDPOMCis2PhP showed better third-order NLO (χ3 = 2.60 × 10−10 esu and β = 8.26 × 10−11 cm/W) than WDPOMCis2PyP (χ3 = 2.25 × 10−10 esu and β = 5.60 × 10−11 cm/W), which is supported by lifetime decay values. The lifetime decay value for WDPOMCis2PhP (τ1 = 2.77 ns) is shorter than WDPOMCis2PyP (τ1 = 6.02 ns). In addition to the factors mentioned based on substituent impact and molecular geometry, the WDPOMCis2PyP has a larger dipole moment than other POM-based porphyrin hybrids, which accounts for the improved third-order NLO response. Minor energy variance among singlet, triplet excited states, and charge-separated states favors quicker intersystem crossing of the WDPOMCis2PyP and WDPOMCis2PhP, which boosts NLO responses, and this actually makes WDPOMCis2PyP and WDPOMCis2PhP better than their corresponding POMs free porphyrins Cis2PyPTris and Cis2PhPTris, leading to their uses in optical devices.

Effects of agitation intensity and foam stability on the Floc-flotation of ultrafine minerals using a laboratory flotation column

In the present study flocculation flotation (floc-flotation) of ultrafine hematite and quartz was investigated in a laboratory-scale flotation column. A direct flotation scheme was used to float hematite using in-house synthesized n-octyl hydroxamic acid (OHA) as a collector. A polymer system containing tannic acid (TAN) and poly(ethylene oxide) (PEO) was used to flocculate quartz to reduce its entrainment. The effects of agitation intensity and foam stability on floc size distribution, entrainment reduction, and flotation kinetics/recovery were investigated. It was shown that the dual polymers TAN-PEO were effective in reducing quartz entrainment, and that the degree of entrainment reduction was affected by the intensity of agitation. A correlation was established between the mean floc size and a reduction in quartz entrainment. TAN-PEO dual polymer system also enhanced the flotation kinetics and recovery of hematite by OHA, originating from a synergistic effect between PEO and OHA. Therefore, higher separation efficiency was achieved from synthetic ultrafine hematite and quartz mixtures when TAN-PEO was added after OHA. The underlying mechanisms were studied by floc size distribution, surface tension, and foam height and decay time measurement. This work helps understand the relationship between hydrodynamic condition, flocs size, and mechanical entrainment when polymeric flocculation is used for entrainment reduction in fine and ultrafine minerals flotation.

Cooperative luminescence of Yb3+ ions in multisite YAM crystal

A series of Yb3+-doped yttrium aluminum monoclinic Y4Al2O9 (Yb:YAM) single crystals with Yb3+ ion concentrations of 0.1, 1, 5 and 10 at.% was grown by means of micro pulling down method. Blue emission was observed in Yb3+ activated YAM crystals under infrared site-selective laser excitation. Through the excitation and emission spectra, decay time measurements and excitation intensity dependence the process responsible for this anti-Stokes emission was assigned to the cooperative deexcitation of two Yb3+ ions. The results show that at 10% Yb3+ dopant concentration investigated system could be considered as single-site system in which cooperative luminescence is dominated by the energetically lowest Yb3+ site. Theoretical cooperative emission spectrum and the cooperative luminescence rate of Yb3+:YAM were calculated.

Luminescence studies of high color purity red-emitting [formula omitted] phosphor prepared by microwave-assisted synthesis technique

A set of red-emitting phosphor materials (Ca1−xAl4O7:Eux3+, x = 0, 0.01, 0.03, 0.05, 0.07, 0.09, 0.11, 0.13) were synthesized through microwave-assisted combustion synthesis for the first time. The crystal structures and phase purity of Eu3+ ions-activated calcium dialuminate (CaAl4O7) phosphor were investigated by XRD study and Rietveld refinement analysis were performed. The prepared phosphors exhibit monoclinic crystal structure having C2/c space group. From the radius difference percentage calculation, the occupancy of Eu3+ ions in Ca2+ sites was confirmed which is in better harmony with the refinement result. Morphological analysis was investigated through SEM study. Structural characteristics and the presence of the functional groups were analysed though FTIR study. The optical band gap (Eg) was determined to be 5.46 eV by studying the UV–VIS reflectance spectra. PL measurements were carried out for the prepared material to study the luminescent behaviour. The presence of charge transfer band was observed in the excitation spectra. It is found that the prepared phosphor materials exhibits emission rich in red at 611 nm with fixed excitation wavelength at 393 nm. The concentration quenching and energy transfer kinetics were analysed by employing Blasse and Dexter’s formula that attributed the non-radiative energy transfer to the dipole-dipole (d-d) interactions. Local site symmetry was analysed to study the symmetry of the environment in the neighbourhood of Eu3+ ions in the host matrix. To analyse the colorimetric performance of the phosphor materials, the correlated color temperature (CCT), color purity were calculated by using the CIE chromaticity co-ordinates (CIE 1931). The calculated CCT value shows the appearance of the emitted color of the phosphor in the warmer region. CaAl4O7:Eu3+ phosphor manifests high color purity which was found to be 97.39 %. The PL decay time measurement were performed for Ca1−xAl4O7:Eux3+ (x = 0.07) phosphor to obtain the decay lifetime. The estimated decay time (1.44 ms) indicates that the prepared phosphor material has a good potency to be utilized as a red-emitting phosphor for wLED, display technology and other applications.

Efficient tunable temperature sensitivity in thermally coupled levels of Er3+/Yb3+ co-doped BaBi2Nb2O9 ferroelectric ceramic

Er3+/Yb3+ co-doped ferroelectric ceramic BaBi2-0.04-yNb2Er0.04YbyO9 (y = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.12) are prepared by solid-state method and investigated for their structural and upconversion luminescence properties. High-resolution X-ray pattern investigation confirmed the ceramic's orthorhombic structure. Microstructure of sintered ceramic surface resembles plate-like structures and consists of non-uniform grains that are randomly oriented. Upconversion luminescence (UCL) spectra revealed two prominent green emission bands near 535 and 557 nm and a notable red band at 672 nm, corresponding to a 980 nm excitation wavelength. Decay time measurements support the effective energy transfer from Yb3+ to Er3+ ions. The average lifetime increases with increasing Er3+/Yb3+ doping concentration up to the optimal concentration (y = 0.10). Pump power dependence demonstrates that two photons are required to generate green and red UC illumination. The absolute sensitivity, Sa (0.69% K−1 and 0.58% K−1) and relative sensitivity, Sr (1.1% K−1 and 1.01% K−1) have been recorded for the first time on Er3+/Yb3+ co-doped BaBi2-0.04-yNb2Er0.04YbyO9 ceramic at y = 0.06 and 0.10, respectively, suggesting it is a viable non-contact sensor ceramic whose sensitivity can be tuned by varying dopant concentrations.

Tunable white light photoluminescence of a single phase Tm3+/Tb3+/Eu3+ codoped GdPO4 phosphor

The present study describes the production of triply-doped GdPO4 and its optical characteristics. Structural information of the prepared material has been investigated by using X-ray diffraction and Fourier transform infrared spectroscopy. The material synthesized crystallizes into a single monoclinic crystal of space group P 21/n. The excitation curves of photoluminescence of single doped GdPO4: Tm3+, Tb3+, and Eu3+ are recorded and their emission spectra are analyzed. Triple-doped material emits multi colour light after a single UV stimulation. White light emission was seen in both triply-doped GdPO4 with variable Tm3+ concentration and triply-doped GdPO4 with variable Eu3+ concentration. GdPO4 doped with Tb3+ (7 mol%), Tm3+ (1.5 mol%), and Eu3+ (2 mol%) has colour coordinates (x = 0.3290, y = 0.3291) approximately near the value of typical white colour coordinates (x = 0.333, y = 0.3333). Furthermore, the transfer of energy in Tm3+, Tb3+ and Eu3+ in triple doped phosphor with varying Eu3+ concentrations was explained. Electric dipole-dipole interaction is used to justify and describe the process of energy transfer from Tb3+ to Eu3+. Decay time measurements were performed to explain energy transfer. Colour rendering index (CRI), Corelated colour temperature (CCT), Quantum efficiency and thermal stability of the prepared phosphor was calculated. All these parameters infer that GdPO4 doped with Tm3+, Tb3+ and Eu3+ may have potential application in white LEDs.

Peculiarities of measuring fluorescence decay times by a streak camera for ps-TALIF experiments in reactive plasmas

We present a detailed methodology for (i) correctly configuring a streak camera to capture raw picosecond two-photon absorption laser induced fluorescence signals (ps-TALIF) of H-atom in low- and atmospheric-pressure plasmas, and (ii) properly processing the recorded raw experimental data with a dedicated mathematical signal processing method to infer actual ps-TALIF signals of H-atom. The goal is the accurate determination of the decay time of the recorded ps-TALIF signals of H-atom. A ps-laser is used to excite atomic hydrogen produced in both plasmas and the raw fluorescence signals are detected by the streak camera using different time windows/ranges (TR). It is shown that the choice of the TR affects the shapes and the decay times of the recorded raw TALIF signals. This is defined as the instrumental function of the streak camera and has a Gaussian profile as determined by recording the ultrafast laser pulse at different TR. To remove this instrumental distortion and extract the actual shape of the TALIF signals, the captured raw TALIF signals were fitted using the mathematical procedure developed in this study, which involved an exponentially modified Gaussian function. The application of our methodology leads to more reliable measurements of hydrogen atoms decay times after respecting the following acquisition conditions: (i) the TR of the streak camera should be sufficiently large to capture the complete (raw) TALIF signal, and (ii) the time width of the instrumental function of the streak camera should be as small as possible compared to the actual decay time of the fluorescence, while ensuring an optimal signal-to-noise ratio. This work demonstrates the remarkable potential of the combination of ps-TALIF and streak cameras in state-of-the-art optical plasma diagnostics.

Enhanced near-infrared emission of Er3+ as a synergistic effect of energy transfers in Bi3TeBO9:Yb3+/Er3+ phosphors

Enhanced near-infrared emission at 1531 nm of Er3+ ions excited by Bi3+ and/or Yb3+ ions was revealed in Bi3TeBO9:Yb3+/Er3+ phosphors. The microcrystalline powders investigated: Bi3TeBO9:Er3+, Bi3TeBO9:Yb3+ and Bi3TeBO9:Yb3+/Er3+ were synthesized by means of the modified Pechini method. Their hexagonal structure with P63 space group was confirmed by XRD measurements. The morphology of the above-mentioned samples was analyzed using SEM technique. The results of μ-Raman investigations showed low phonon energy of Bi3TeBO9 matrix. The characteristic Er3+ emission at 1531 nm assigned to the 4I13/2 → 4I15/2 transition in Bi3TeBO9:Er3+ and Bi3TeBO9:Yb3+/Er3+ powders was excited by Bi3+ or Yb3+ ions (the 1S0 → 3P1 or 2F7/2 → 2F5/2 transitions) upon their excitation at 327 or 975 nm, respectively. It was revealed that the effective energy transfer from the excited Bi3+ ions (at 327 nm) directly to Er3+ ions or indirectly to Er3+ ions both via the excitation of Bi3+ ions in VIS range or excitation of Yb3+ ions in the NIR range results in synergistic effect, which produces enhanced emission at 1531 nm of Er3+ ions in Bi3TeBO9:Yb3+/Er3+ system. Moreover, it was found that the effective energy transfer from the excited Yb3+ ions (at 975 nm) directly to Er3+ ions results in the efficient emission at 1531 nm of Er3+ ions. Furthermore, the calculations of energy transfer efficiency and quantum efficiency proved the effective energy transfer from Bi3+ to Yb3+ and from Yb3+ to Er3+ ions. The corresponding mechanisms of energy transfer processes in the investigated materials were discussed on the basis of reflectance, excitation and emission spectra and measured decay times. The results indicate a potential of the use of Bi3TeBO9:Yb3+/Er3+ powders as spectral converters in new generation of photovoltaic devices.

Optical and luminescence studies of Nd3+ doped phosphate glasses for pulsed laser applications

A series of glass with appropriate chemical compositions (60-x) P2O5 + 20 Bi2O3 + 10 SrF2 + 10 Na2 CO3 + x Nd2O3, (x = 0.1, 0.5, 1.0, 1.5, and 2.0% by mole) were prepared by using the melt quenching technique. The glass phase structure was confirmed by using X-ray diffraction technique. The structural analysis using FTIR technique it reveals characteristic bonding vibrations and different functional group in the glass matrix. The elements present in the fabricated glass sample was analyzed by using EADX spectrum. J-O intensity parameters Ω2, Ω4, and Ω6for the currently being researched PBNSNd10 glass have values of 9.80 × 10-20 cm2, 3.305 × 10-20 cm2, and 5.576 × 10-20 cm2 sequentially. The J-O parameters shows a trend of Ω2 > Ω6 > Ω4. The near infrared emission spectra recorded with 808 nm laser diode excitation for various concentrations of neodymium ions show the emission intensity is highest for the 4F3/2 → 4I11/2 transition at 1056 nm. The measured decay times 4F3/2 level decreased with increasing Nd2O3 ions because of concentration quenching effect. The obtained results in present study have been compared with previous results obtained for Nd2O3 doped glasses.

Synthesis and characterization of a luminescent diphosphine and aromatic N-heterocyclic copper(I) coordination polymer

Luminescent Cu(I) complexes have drawn considerable attention as alternative materials to precious transition metal complexes due to their low cost and electron configuration. Discrete heteroleptic diamine-diphosphine copper(I) complexes have been investigated owing to their outstanding photophysical features. However, heteroleptic copper(I) coordination polymers remain mostly unexplored. Herein, we report the synthesis and photophysical characterization of a heteroleptic copper(I) coordination polymer by employing bidentate oxybis(2,1-phenylene)bis(diphenylphosphine) (POP) diphosphine and nitrogen heterocyclic 5-[4-(1-imidazolyl)phenyl]-2H-tetrazole (ipt) as ligands. By utilizing the mixed-solvent strategy, a one-dimensional (1D) linear chain was constructed under solvothermal reaction conditions. Temperature-dependent emission spectra combined with decay time measurements demonstrate that emission originated from triplet phosphorescence at ambient temperature.

Ho3+ doped low-phonon single crystals and chalcogenide glasses for mid-IR source application

A comparative study was conducted to investigate the 3.9 µm mid-IR emission properties of Ho3+ doped NaYF4 and CsCdCl3 crystals as well as Ho3+ doped Ga2Ge5S13 glass. Following optical excitation at ∼890 nm, all the studied materials exhibited broad mid-IR emissions centered at ∼3.9 µm at room temperature. The mid-IR emission at 3.9 µm, originating from the 5I5 → 5I6 transition, showed long emission lifetime values of ∼16.5 ms and ∼1.61 ms for Ho3+ doped CsCdCl3 crystal and Ga2Ge5S13 glass, respectively. Conversely, the Ho3+ doped NaYF4 crystal exhibited a relatively short lifetime of ∼120 µs. Temperature dependent decay time measurements were performed for the 5I5 excited state for all three samples. The results showed that the emission lifetimes of Ho3+:CsCdCl3 and Ho3+:Ga2Ge5S13 were nearly temperature independent over the range studied, while significant emission quenching of the 5I5 level was observed in Ho3+:NaYF4. The temperature dependence of the multi-phonon relaxation rate for 3.9 µm mid-IR emission in Ho3+:NaYF4 crystal was determined. The room temperature stimulated emission cross-sections for all three samples were calculated using the Füchtbauer-Landenburg equation. Furthermore, the results of Judd-Ofelt analysis are presented and discussed.

Fast scintillating Ce3+ doped gadolinium aluminum fluoroborate glass for calorimetry in proton CT prototype: A preliminary work

In this work, Ce3+-doped gadolinium aluminum fluoroborate glass scintillators, 25Gd2O3-(65-x)B2O3–10AlF3-xCeF3, where, x = 0, 0.05, 0.1, 0.2, and, 0.3 mol%, were prepared and studied systematically for developing a proton calorimeter used in proton-computed tomography. Various properties of the prepared glass scintillators were evaluated through density, X-ray absorption near edge spectroscopy, transmittance, photoluminescence, decay time, X-ray-induced luminescence, and proton-induced luminescence measurements. The highest density of the fabricated glass scintillators reached 4.31 g/cm3. The X-ray-induced luminescence showed a broad emission band centered at approximately 400 nm, and the decay time was less than 30 ns. The glass scintillators were irradiated by a proton beam with a beam energy of 100–115 MeV. It was found that the glass scintillators emitted light at almost the same wavelength as that of the X-ray-induced luminescence. Moreover, the energy deposition inside the fabricated glass scintillators was simulated using GATE simulation and compared with the results obtained for proton-induced luminescence. The energy deposition obtained from the simulation showed the same trend as that for the fraction of light emitted from the proton irradiation measurement. Therefore, these fabricated glass scintillators can be used as calorimeter in medical physics and other applications related to proton or X-ray irradiation.