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(Gd,Y,Ce)3(YxGa1−x)2GaAl2O12 (GYGAG:Ce) scintillation ceramics with different Y excess, where x = 0.005−0.08, were fabricated by the solid-state reaction method. The effects of stoichiometry on the phase composition, optical quality, and microstructure of GYGAG:Ce ceramics were analyzed. GYGAG:Ce ceramics have a pure garnet phase and obtain good in-line transmittance when x < 0.04, while more Y excess leads to the creation of the secondary phase. The change of x value influences the sintering behavior of the GYGAG:Ce ceramics: The excess of Y works as the self-sintering aid and significantly reduces the sintering temperature of ceramics. When x = 0.01–0.04, the X-ray excited luminescence (XEL) spectra and light yields of GYGAG:Ce ceramics are similar. The fast scintillation decay time and afterglow intensity of GYGAG:Ce ceramics show a slight decrease with increasing x value. Finally, additional 50–500 ppm MgO and 100–500 ppm CaO were introduced to the GYGAG:Ce ceramic with x = 0.04, and both were found to significantly increase the fast scintillation component and reduce the afterglow intensity by two orders of magnitude to 0.01% after X-ray cut-off.

Tb3+ doped BaAl2O4 phosphors (0–9.0 mol%) were prepared through sol–gel combustion method. The crystal structure, morphology, chemical composition, photoluminescence (PL), afterglow and thermoluminescence (TL) glow curve of Tb3+ doped BaAl2O4 were investigated by means of X-ray diffraction, scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy, PL spectroscopy, afterglow spectroscopy, and TL dosimetry. Characterizations of the PL and afterglow spectra indicate that both Tb3+ doping species and oxygen vacancies act as the luminescence center of PL whereas only Tb3+ dopant works as the luminescence center of afterglow for Tb3+ doped BaAl2O4. The green afterglow of Tb3+ doped BaAl2O4 lasts for about 214 min at the optimal doping concentration of about 1.0 mol%. The profile of TL glow curve of Tb3+ doped BaAl2O4 heavily depends on the doping concentration, and the evolution of the TL glow curve with doping concentration reveals that doping BaAl2O4 with Tb3+ can significantly modify the distribution of carrier traps in the phosphor. The effects of Tb3+ doping on the PL, afterglow, and TL glow curve of Tb3+ doped BaAl2O4 are discussed in terms of the creation, recombination, and neutralization of defects in BaAl2O4. This work proves that doing with Tb3+ species is a general and robust strategy for endowing BaAl2O4 with highly efficient green afterglow. This “defect engineering” approach enables ultra-long afterglow for Tb3+ doped BaAl2O4 when defect centers in the phosphors are optimized.

In this paper, we will address the several factors underlying the performance of scintillators in terms of light yield and energy resolution in the high-end medical imaging applications CT (Computed Tomography) and PET (Positron Emission Tomography. The state-of-the-art scintillators that are being applied in these modalities are discussed as well. We also address important scintillator properties like light yield, decay time and afterglow, energy resolution and the corresponding material- and activator choices. Finally, an outlook on these materials and technologies is presented.

Multi-color fluorescent anti-counterfeiting technology possesses a wide range of application prospects. However, there is still a challenge on the development of new single-component multi-color fluorescent materials related to the excitation wavelength. Herein, we report an efficient multi-peak luminescent material, Sb3+, Mn2+ co-doped CsCdCl 3 , which emission with a long afterglow is related to the excitation wavelength. There are two independent energy transfer channels of Mn2+ under short- and long-wave excitation. Under 357 nm excitation, dual-emission is observed at 506 and 590 nm attributed to the 3P 1 –1S 0 and 4T 1 -6A 1 transitions of [SbCl 6 ]3- and Mn2+ ions, respectively. Under 254 nm excitation, the microcrystals have orange emission. Excitation wavelength-dependent and tunable dual-emission associated with the host self-captured excitons and [SbCl 6 ]3- to Mn2+ energy transfer. The microcrystal's afterglow time at room temperature is 3500 s, which is attributed to the modulation of the trap for Mn2+. These results indicate that the material has potential applications in the field of multicolor fluorescent anti-counterfeiting. [ABSTRACT FROM AUTHOR]

In afterglow phosphors, luminescence appears and can be observed with the naked eye for minutes to hours or more, even after photoexcitation ceases. Red afterglow and photostimulated luminescence (PSL) at 650 nm are studied in CaS:Eu2+, Mn2+ phosphors. Infrared light at 980 nm from a laser diode induces the red PSL for 990 s. Two types of trap states are found to be present in the phosphors by using thermoluminescence (TL). Deep trap states are reflected in a TL peak in the temperature region of 520 K, and are related to PSL. Shallow trap states reflected in the other TL peak at 250 K are related to afterglow. The intensity dependence of photoexcitation on PSL shows that carriers are more easily accumulated in the deep trap states than shallow trap states. Experiments of electron paramagnetic resonance are conducted to discuss the possible origins of PSL and the afterglow. [ABSTRACT FROM AUTHOR]

Living system involves a plenty of delicate processes where a tiny structural variation of biological substance may lead to drastic change of the fate of the living system. Inspired by this, in artificial photofunctional systems, if tiny structural variation changes the fate of excited states, a new class of advanced material would emerge for optical analysis, sensing, and next‐generation display is reasoned. However, such delicate processes remain rarely explored in photofunctional systems, especially in room temperature organic afterglow systems. Here the attachment/detachment of methoxy group can switch off/on twisted intramolecular charge transfer property in difluoroboron β‐diketonate systems is reported. In addition, structural isomerization triggers afterglow transformation from room temperature phosphorescence to thermally activated delayed fluorescence. These observations are helpful for better photophysical understanding on luminescence systems and advanced material design. [ABSTRACT FROM AUTHOR]

Herein, a coordination trap strategy is proposed for constructing stimulus‐responsive phosphorescent perovskites. Hydroxyl groups are selected as trap groups and introduced into benzylamine hydrochloride of Cd‐based perovskite. The resulting two‐dimensional (2D) perovskite (C7H10NO)2CdCl4·H2O (H1) exhibits blue fluorescence at 405 nm and green phosphorescence at 482 nm under 365 nm excitation. After introducing guest Mn2+, due to the passivation of defects, the doped H1 (H1‐M) achieves orange phosphorescence (λ = 615 nm) of Cd2+. Interestingly, because thermal stimulation induces the coordination of hydroxyl groups with metal ions, H1 and H1‐M are transformed into the zero‐dimensional (0D) perovskite (C7H10NO)2CdCl4 (H2) and doped H2 (H2‐M), respectively. The coordination immobilizes the organic molecules, thus resulting in a large increase in the phosphorescence lifetime and a strong green afterglow of H2. The coordination also transforms the luminescent center of the doped perovskite from the host metal ion of H1‐M to the guest metal ion of H2‐M, achieving red phosphorescence of Mn2+ at 685 nm. Under water vapor, H2 and H2‐M are reversibly converted to H1 and H1‐M, respectively. Based on the above phenomena, a multilevel anti‐counterfeit encryption system with water/heat stimulus‐response is developed, which provides a new idea for the design of stimulus‐responsive phosphorescent intelligent materials. [ABSTRACT FROM AUTHOR]

A state-of-the-art semi-analytic gamma-ray burst (GRB) afterglow model with synchrotron self-Compton (SSC) emission has been applied for the first time for parameter inference using real GRB data. We analyzed the famous GRB 190114C as a case study. GRB 190114C, characterized by its long duration and high luminosity, was observed by many ground-based and orbiting telescopes spanning a wide range of electromagnetic wavelengths, from radio to GeV gamma rays. We used two advanced algorithms for inference: a nested sampling algorithm called UltraNest and an MCMC algorithm emcee. Evoking the standard afterglow model, the inference result and the best-fit values lead to an initial bulk Lorentz factor (a rough estimate of Γ = 526 ), which aligns with the values often seen in GRBs identified by the Fermi-LAT instrument. Similarly to the best-fit values of other studies in the literature, the derived values of microphysical parameters, the circumburst density, and the kinetic efficiency are consistent with those found after modeling the multi-wavelength observations in GRB 190114C. We show that the SSC from the forward-shock region can only describe the highest-energy photons above a few GeVs. [ABSTRACT FROM AUTHOR]

Ce-doped 20CsCl-20SrCl2-60ZnCl2 glasses were investigated for their optical and scintillation properties. Under X-ray irradiation, a broad emission peak at approximately 350 nm with a shoulder peak at 375 nm was observed, and its origin was attributed to Ce3+. In the pulse height spectrum under 241Am a-ray, the glass doped with 0.05% Ce exhibited the highest light yield (LY) of 25 ph/MeV (138 ph/5.5MeV-a) among zinc-halide-based glasses. The afterglow levels of the samples were superior to that of commercial CsI:Tl. [ABSTRACT FROM AUTHOR]

Solid-state materials with long-persistence phosphorescence always suffer serious thermal quenching effect that greatly hinders their applications at high-temperature conditions (>373 K). Therefore, developing high-temperature phosphorescence (HTP) materials remains a great challenge. In this work, cytosine (Cyt) is hybridized with indium chloride into zero-dimensional (Cyt)2[InCl5·H2O] (CICH). A green afterglow up to 1.0 s is observed at room temperature for CICH but almost quenched at 448 K due to the serious thermal quenching effect. Upon removing the coordinated H2O molecules of CICH (denoted to CIC), CIC shows an excellent performance of HTP with a persistence time of 0.4 s even at 448 K. The greatly improved thermal resistance is attributed to the removal of coordinated H2O molecules, which leads to a reduced free volume of Cyt, thereby suppressing the molecular vibration and rotation. Additionally, the afterglow time of CICH can be facilely tailored through Sb3+ doping due to efficient triplet energy transfer. At last, given the high thermal tolerance of CIC, a temperature-sensitive anticounterfeiting is successfully demonstrated. [ABSTRACT FROM AUTHOR]

Carbon dots (CDs), as emerging long afterglow luminescent material, have attracted the attention of researchers and become one of the hot topics in long afterglow materials. In recent years, researchers have obtained a series of CDs‐based long afterglow materials with different properties utilizing matrix‐assisted and self‐protective methods. To meet diverse application needs, the development of multicolor CDs‐based long afterglow materials is a focus and challenge in this field. Most of the previously reported CDs‐based long afterglow materials generally emit blue or green afterglow. Recently, some multicolor systems have been discovered, and the emission range can extend from ultraviolet to near‐infrared. However, there is a lack of systematic and in‐depth analysis regarding the preparation strategy and luminescence mechanism of multicolor afterglow from CDs‐based long afterglow materials. Based on this, this review summarizes the preparation strategies of multicolor afterglow from raw materials and reaction parameters. Then, the luminescence mechanisms of multicolor afterglow are analyzed from seven factors, including carbonization degree, surface state, aggregation degree, temperature dependence, excitation dependence, multi‐emission center, and energy transfer. Moreover, the applications of multicolor afterglow from CDs‐based long afterglow materials are introduced. Finally, the problems and challenges in this field are discussed, and the future development directions are analyzed. [ABSTRACT FROM AUTHOR]

In astronomy, gamma-ray bursts (GRBs) are some of the most intriguing and enigmatic phenomena. GRBs are the most luminous events in the cosmos, and they are bursts of strong but brief gamma-ray (GR) flashes. GRBs have a highly interesting nature and can last anywhere from a few hundred seconds to a tiny fraction of a second. A GRB produces an afterglow that lasts longer and gradually fades. The discovery of afterglow has brought about a revolution in the area of GRB. We have discussed GRBs and their classifications in this paper. Moreover, we summarized the mechanisms behind the bursts, the features seen, the afterglow, and the fireball model of GRBs. Apart from the fireball model of GRBs, alternative models are also discussed, for example, the accretion model for the long GRBs and the pulsar model used to explain the short GRBs. [ABSTRACT FROM AUTHOR]

Recently, long persistent phosphors (LPPs) have attracted significant attention as promising candidates for biomedical applications. However, the serious decrease in luminescence intensity in tissue still remains a major challenge. Therefore, exploring more competitive LPPs and achieving reproducible tissue imaging is crucial. In this study, a new series of near‐infrared (NIR) phosphors La3Ga5Sn1‐xO14:xCr3+ (x = 0.005–0.05) were synthesized using a high‐temperature solid‐state method. The as‐synthesized samples were characterized using X‐ray diffraction, diffuse/photoluminescence spectroscopy, fluorescence decay curves, and thermoluminescence spectroscopy. Upon excitation with ultraviolet light, strong emission bands were observed in the range 600–1200 nm with an optimal doping concentration of x = 0.02 mol. Moreover, La3Ga5SnO14:Cr3+ exhibits persistent luminescence due to the presence of suitable energy traps, which prompted the phosphor to emit NIR light even after the removal of the excitation source. [ABSTRACT FROM AUTHOR]

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Gadolinium pyrosilicate (GPS, Gd2Si2O7) single crystals with different doping concentrations of Tb (0.1–2.0 mol%) are successfully fabricated using the floating-zone technique. In this work, the dependence of Tb-doping concentration on the photoluminescence (PL) and scintillation properties of Tb-doped GPS (Tb:GPS) has been investigated. The PL emission contour graph shows multiple emissions, with the strongest emissions at 378 nm for 0.1% and 0.5% Tb-doping and 544 nm for 1.0% and 2.0% Tb-doping, corresponding to Tb3+ 4f-4f transitions. The PL lifetimes of the specimens range from 4.89 to 5.22 ms. The scintillation spectra exhibit comparable wavelength and intensity trends to the PL emission. The scintillation lifetimes of the specimens range from 2.41 to 3.88 ms. The Tb:GPS specimens demonstrate a relatively excessive afterglow level, with Af20 values ranging from 1640 to 7250 ppm and Af40 values ranging from 136 to 362 ppm. Using recently developed pulse height measurement for millisecond decay scintillators, under excitation at 662 keV γ-rays, the 1.0% Tb:GPS specimen exhibits the highest scintillation light yield among all other specimens at 95,600 ph/MeV, making Tb:GPS one of the highest light yield oxide scintillators.

This study aims to prepare the self-luminous pavement marking (SLPM) to enhance driving safety and reduce the risk of traffic accident. Firstly, the composition of the SLPM was determined by the mechanical properties and luminous performance tests. The optimal mass proportions of epoxy resin, toughening agent, curing agent, curing accelerator, luminous powder, reflective powder, glass bead and glass powder was 1.0:0.1:0.3:0.006:0.4:0.3:0.25:0.55. In addition, test results showed that the SLPM has satisfactory mechanical properties, durability and luminous performance, which met the engineering requirements for practical application. The afterglow time was more than 11 h at night in laboratory test. Moreover, it is feasible to prepare different colors of the SLPM according to the RGP principle. The afterglow color and luminous intensity of SLPM strongly depend on the luminous material and its proportions. Overall, this paper provides a reference for designing and applying SLPM materials in road engineering.

In this paper, X-ray induced color-tunable long afterglow luminescent material Ca 9-x Tb(PO 4) 7 :xMn2+ was synthesized by high-temperature solid state reaction. The effects of Mn2+ doping concentration on the properties of the samples were studied by XRD, SEM, fluorescence and afterglow spectra. The results showed that there was a very efficient energy transfer between Tb 3+ and Mn 2+ under X-ray excitation, with a transfer efficiency of up to 94.6%, which also contributed to the tunable green-red emission. With the increase of Mn2+ concentration, the green afterglow emissions of Tb3+ mainly at 546.9 nm gradually decreased and even disappeared, while the red afterglow emissions of Mn2+ at 647.3 nm gradually increases due to excellent energy transfer. When the doping concentration of Mn2+ was 0.07, the red afterglow emissions were the strongest. Furthermore, even at low-dose radiation (3 mGy), the sample still possessed excellent afterglow performance, which can persist for more than 5 h. In addition, the samples also showed excellent photostimulated luminescence properties, which can be persist for many cycles by the irradiation of 980 nm laser. The thermoluminescence results revealed that the doping Mn2+ ions can not only enhance the trap concentrations obviously but also created new deep traps with trap depth of 0.864 eV, which thus resulted in better long afterglow luminescence and photostimulated luminescence properties of Ca 9 Tb(PO 4) 7 :Mn2+. [ABSTRACT FROM AUTHOR]

Long-lifetime room-temperature phosphorescence (RTP) materials have various applications in many fields due to their long-lived emission and large signal-to-noise ratio. However, it is not easy to attain long-lifetime RTP materials owing to the spin-forbidden nature of triplet exciton transitions. Herein, yellow phosphorescence carbon-dot-based composites embedded in a MgO matrix (MgCDs) have been developed, and the lifetimes were up to 1.81 s (more than 11 s to the naked eye) in a solid state and 254 ms (more than 9 s to the naked eye) in water. X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), and XPS analyses were performed, and the structural characterizations indicate that carbon dots (CDs) embedded in the rigid magnesium oxide matrix restrict the vibration and rotation of CDs chromophores and suppress nonradiative recombination of triplet excitons. Further studies unveiled that the barrier effect of the insoluble MgO matrix on oxygen is likely mainly responsible for the observed long-lived RTP in water. In addition, the codoping of N, P, and Mg elements, as well as the carbonization degree, play an important role in the luminescence properties of MgCDs. Last but not least, applications in bioimaging, screen printing, anticounterfeiting, and information protection are also explored. This work offers fresh ideas for developing ultralong lifetime afterglow materials that can be applied in versatile applications. [ABSTRACT FROM AUTHOR]

As novel stress‐sensing materials, the reported mechanoluminescence (ML) phosphors work only at or above room temperature. Herein, the ML response to low temperatures (77 K) is extended by employing ultra‐shallow traps. Strong ML stimulated by handwriting force followed by persistent luminescence is observed in BaSi2O2N2:Eu2+ (BSON) at 77 K. The UV pre‐irradiated BSON can still keep the characteristics of ML with 45% intensity after 300 min. Abundant ultra‐shallow traps with depth of ≈0.19 eV are found and revealed to be responsible for the low‐temperature ML and persistent luminescence. Manipulation of the ultra‐shallow traps is realized by doping Ge, Er, and Ce ions in BSON, leading to significant ML enhancement at 77 K. Together with ML, the ultra‐shallow traps also exhibit force memory ability to replicate the pre‐applied force pattern simply by afterglow. The finding advances the state‐of‐the‐art in force sensing under low temperature conditions. [ABSTRACT FROM AUTHOR]

A toroidal Alfvén eigenmode (TAE) has been observed to be driven by alpha particles in a JET deuterium-tritium internal transport barrier plasma. The observation occurred 50 ms after the removal of neutral beam heating (NBI). The mode is observed on magnetics, soft-xray, interferometry and reflectometry measurements. We present detailed stability calculations using a similar tool set validated during deuterium only discharges. These calculations strongly support the conclusion that the observed mode is a TAE, and that this mode was destabilized by alpha particles. Non-ideal effects from the bulk plasma are interpreted as responsible for suppressing the majority of TAEs which were also driven by alpha particles, but the modes that match the observations are predicted to be particularly weak for these non-ideal effects. This mode located far from the core on the outboard midplane is found to be driven by both trapped and passing particles despite alpha particles originating in the core. [ABSTRACT FROM AUTHOR]

Manganese (Mn) doped MgGa2O4 (MGO) phosphors are prepared by a solid‐state reaction technique in air. Upon UV light excitation, the featured green and red emissions of Mn2+ and Mn4+, respectively, are detected in the Mn‐doped MGO phosphors, indicating the incomplete self‐reduction behavior of Mn in the MGO host lattices. To clarify the incomplete self‐reduction behavior, theoretical calculations based on density functional theory and bond energy theory are performed. Moreover, the self‐reduction behavior of Mn can be manipulated by the incorporation of Li+, leading to the precise regulation of the Mn2+ and Mn4+ contents in the MGO host lattices. Based on the ionic radii, the inhibited self‐reduction mechanism is triggered by Li+ occupying the tetrahedral Mg2+ site, leading to the reduced occupancy of tetrahedral Mg2+ sites by Mn ions, and forcing Mn to take up the octahedral Ga3+ sites. Furthermore, the afterglow properties of phosphors with wide and continuous multiple traps are studied in detail. Finally, based on unique luminescence properties of the phosphors, their potential application in ratiometric optical thermometer and optical anti‐counterfeiting is also systematically exploited. [ABSTRACT FROM AUTHOR]

Multimodal luminescence has emerged as a promising solution in the realm of anti-counterfeiting techniques, which have gained global attention due to their association with information and data security. The conventional approach to achieving multimodal luminescence typically involves combining upconversion and downshifting luminescence, which necessitates the use of external excitation sources and costly detection equipment. Herein, we develop an anti-counterfeiting strategy based on the afterglow performance of NaLuF 4 : Gd, Tm nanoparticles after X-ray excitation. The X-ray-induced Frenkel defects-base traps ensnare electrons with low kinetic energy, resulting in the creation of persistent photon traps that are responsible for the temperature-dependent afterglow intensity. The dual-band and thermo-enhanced afterglow emission can encrypt information well according to our proof-of-concept experiment and the visible light signal can be successfully captured by a smartphone camera. These unique features of NaLuF 4 : Gd, Tm nanoparticles render them highly appealing for multilevel anti-counterfeiting applications. [ABSTRACT FROM AUTHOR]

Anti-counterfeiting technology is of great significance to information security. To obtain high-quality anti-counterfeiting materials, the developments of inorganic materials are crucial. In this paper, a series KGaSiO 4 : x Eu3+ phosphors with persistent luminescence, photoluminescence, and thermochromic have been successfully prepared and the application of quadruple anti-counterfeiting is realized. The X-ray diffraction and Rietveld refinement indicate that the phosphors are pure phase. With Eu3+ ions doping, the structure change, site occupancies, and color-tunable phenomenon are carefully investigated. Different from another Eu3+ doping phosphor, the emission of KGaSiO 4 :0.2% Eu3+ phosphor changes with the excitation light in the region of 240 nm–306 nm. The emission color can be modulated with the surrounding temperature. Surprisingly, this phosphor can emit green afterglow light, which is attributed to the different luminescent properties of the matrix and doping of Eu3+ ions. The series of phosphors exhibit abundant luminescent properties. Based on their wavelength dependence, concentration quenching, long afterglow, and thermochromic properties, the KGaSiO 4 : x Eu3+ phosphors can be effective materials for quadruple-modal anti-counterfeiting devices. [ABSTRACT FROM AUTHOR]

The results of a spectroscopic study and simulation of the processes of population and destruction of the levels of the 2p55s configuration of a neon atom in a decaying plasma of a low-frequency barrier discharge in a He–Ne mixture are presented. Experimental conditions: helium pressure 0.08–22 Torr, neon pressure ≤3 mTorr, electron density less than 1011 cm–3. On the basis of data on the evolution of the populations of the 3si levels (in Paschen's notation) with a change in helium pressure, data on the rate constants of collisional processes that determine the kinetics of these levels in He–Ne plasma are obtained more accurate than those available in the literature. [ABSTRACT FROM AUTHOR]

Solid-state molecules based on room-temperature phosphorescent (RTP) emission have received extensive attention due to their special optical properties of triplet excitons. However, there are still few solid molecular systems with naked-eye-visible afterglow characteristics. Herein, we introduce 4-phenylbenzylamine (namely PBA) with a long conjugated system into common non-toxic In3+ to form an indium-based organic inorganic halide, whose chemical formula is PBA3[InCl6]·H2O. Interestingly, this hybrid halide generates a RTP emission at 617 nm with a lifetime decay as long as 290.4 ms, expressing a naked-eye-visible afterglow for more than 7 s. The mechanism study shows that the long lifetime RTP originated from the specific lamellar stacking of organic molecules and metal halide units, facilitating the interaction between the inorganic layers and organic layers. Therefore, the material can be potentially used in emergency lighting, information security, and other fields. Meanwhile, this work provides a reference for the design and implementation of a more efficient organic-inorganic hybrid system with the ultralong RTP emission. [ABSTRACT FROM AUTHOR]

In recent years, pure organic room‐temperature phosphorescence (RTP) with highly efficient and long‐persistent afterglow has drawn substantial awareness. Commonly, spin‐orbit coupling can be improved by introducing heavy atoms into pure‐organic molecules. However, this strategy will simultaneously increase the radiative and non‐radiative transition rate, further resulting in dramatic decreases in the excited state lifetime and afterglow duration. Here in this work, a highly symmetric bird‐like structure tetraphenylene (TeP), and its three symmetrical halogenated derivatives (TeP−F, TeP−Cl and TeP−Br) are synthesized, while their RTP properties and mechanisms are systematically investigated by both theoretical and experimental approaches. As the results, the rigid, highly twisted conformation of TeP restricts the non‐radiative processes of RTP and gives rise to the enhancement of electron‐exchange, which can contribute to the RTP radiation process. Despite the faint RTP of the bromine and chlorine‐substituted ones (TeP−Br, TeP−Cl), the fluoro‐substituted TeP−F exhibited a long phosphorescent lifetime up to 890 ms, corresponding to an extremely long RTP afterglow over 8 s, which could be incorporated into the best series of non‐heavy‐atom RTP materials reported in previous literature. [ABSTRACT FROM AUTHOR]

Poly(vinyl chloride) (PVC) was reinforced with electrospun glass nanofibres (EGN) to develop photochromic and afterglow materials such as smart windows and anti‐counterfeiting prints. A colourless electrospun glass nanofibres@poly(vinyl chloride) (EGN@PVC) sheet was prepared by physical integration of lanthanide‐doped aluminate nanoparticles (LANP). The low concentrations of LANP in the photochromic and photoluminescent EGN@PVC hybrids displayed fluorescence emission with instant reversibility. EGN@PVC with the highest phosphor concentrations showed persistent phosphorescence emission with slow reversibility. Based on the results of the Commission Internationale de l'éclairage Laboratory and luminescence spectroscopy, the translucent EGN@PVC samples became green in the presence of ultraviolet illumination and greenish‐yellow in the absence of light. According to scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the morphological study of EGN and LANP showed diameters of 75–95 and 11–19 nm, respectively. The morphology of the EGN@PVC substrates was studied using SEM, X‐ray fluorescence, and energy‐dispersive X‐ray spectroscopy. The mechanical characteristics of PVC were enhanced by reinforcement with EGN as a roughening agent. When comparing the scratching resistance of LANP‐free substrate to photoluminescent EGN@PVC substrates, it was observed that the latter was much superior. The photoluminescence spectra were reported to have an emission peak at 519 nm when excited at 365 nm. These findings demonstrated that the luminous transparent EGN@PVC composites had improved superhydrophobic and UV‐blocking characteristics. [ABSTRACT FROM AUTHOR]

BaZrSi3O9:Eu2+, Sm3+ (Em:525 nm) is prepared. The role played by the trivalent co‐doping ion Sm3+ in the afterglow and the type of trap are clarified. BaZrSi3O9:Eu2+, Sm3+ is found to produce Sm2+ during the excitation by X‐ray absorption near‐edge structure (XANES), etc., and it is thus proved that Sm3+ exists as an electron trap in the afterglow process. In the field of persistent phosphors activated by Eu2+ and Re3+ such as Sm3+ or Dy3+ having been widely utilized as emergency guide lights, clock faces, etc. for > 25 years, for the first time it is successfully observed that after excitation Re2+ is formed, transferring its electron to 5d band of Eu2+, returning to Re3+ by itself, where the decrease in Sm2+ coincides with the increase in Sm3+, and the two decay time τ1 and τ2 of PL (5D0→7F0) of Sm2+ coincides with the two evolution time of PL (5d→4f) of Eu2+. The behavior of electron transfer from Sm2+ to Eu2+ as a key of afterglow is detected. The detailed afterglow mechanism is proposed by analysis of thermoluminescence and defect reaction, which is very important for the in‐depth investigation of the long afterglow material and the further improvement of the mechanism. [ABSTRACT FROM AUTHOR]

BaZrSi3O9:Eu2+, Sm3+ (Em:525 nm) is prepared. The role played by the trivalent co‐doping ion Sm3+ in the afterglow and the type of trap are clarified. BaZrSi3O9:Eu2+, Sm3+ is found to produce Sm2+ during the excitation by X‐ray absorption near‐edge structure (XANES), etc., and it is thus proved that Sm3+ exists as an electron trap in the afterglow process. In the field of persistent phosphors activated by Eu2+ and Re3+ such as Sm3+ or Dy3+ having been widely utilized as emergency guide lights, clock faces, etc. for > 25 years, for the first time it is successfully observed that after excitation Re2+ is formed, transferring its electron to 5d band of Eu2+, returning to Re3+ by itself, where the decrease in Sm2+ coincides with the increase in Sm3+, and the two decay time τ1 and τ2 of PL (5D0→7F0) of Sm2+ coincides with the two evolution time of PL (5d→4f) of Eu2+. The behavior of electron transfer from Sm2+ to Eu2+ as a key of afterglow is detected. The detailed afterglow mechanism is proposed by analysis of thermoluminescence and defect reaction, which is very important for the in‐depth investigation of the long afterglow material and the further improvement of the mechanism. [ABSTRACT FROM AUTHOR]

The ability to tune afterglow attributes of organic materials can largely extend their utility in the field of lifetime‐encoded security applications. Herein, the tuning of afterglow intensity and lifetime of molecule emitters after being doped into copolymer by photoinitiated solvent‐free copolymerization are reported. The molar ratio adjustment of 2‐hydroxyethyl acrylate and 2‐hydroxyethyl methacrylate in copolymerization allows systematic tuning of the rigidity of the resultant copolymers by occupying the free volume through methyl groups, enabling controlled stabilization of the in situ generated triplet excitons of the doped molecule emitters via effectively decreasing vibrational energy dissipation. With the use of this strategy, the green afterglow for 2,3‐naphthalenedicarboxylic anhydride can be tuned with a lifetime from 170.1 to 1258.6 ms, accompanied by a 76‐fold intensity enhancement. Furthermore, this strategy can be extended to tune multicolor afterglow materials through the choice of molecule dopants. When combined with digital light processing printing, the strategy allows for the facile fabrication of lifetime‐encoded complex 3D objects with high precisions for security applications. [ABSTRACT FROM AUTHOR]

The paper considers the possibility of using a low-pressure dielectric barrier discharge (DBD) as a plasma source for the active medium of a He–Ne-laser. The results of a spectroscopic study of the decay stage of a DBD plasma of a cylindrical configuration with a pronounced inverse population of the upper level of the 2p55s configuration, which makes the line of 632.8 nm one of the brightest in the visible region of the spectrum, are presented. Based on the analysis of data on the populations of the excited levels of the neon atom and the metastable levels of helium 21S0 and 23S1, it is shown that in the early stage of the DBD afterglow at helium pressures of a fraction of a Torr, the distribution of populations over the 2p55s and 2p54d levels of the neon atom, which is characteristic of the excitation transfer mechanism, is realized. In the late afterglow with the departure of helium atoms He21S0, emission in the visible region of the spectrum is formed mainly by transitions from levels of the 2p53p, configuration, the population of which is associated with He(23S1) atoms. At this stage, the population of the 2p55s and 2p54d states by electron–ion recombination processes is ineffective and does not lead to the formation of population inversion. As an optimal solution in terms of the 632.8 nm line brightness in the afterglow, it is proposed to use a discharge with electrodes along the outer surface of a cylindrical discharge tube, initiated at frequencies that exclude the recombination stage of the afterglow. [ABSTRACT FROM AUTHOR]

Polypropylene textiles have been used in the development of various industrial products, such as automotives, plastic furniture, and medical tools. However, polypropylene resists dyeing due to a deficiency of active staining spots. Here, we developed a new strategy towards new afterglow and photochromic fibres from recycled polypropylene plastics using plasma‐supported coloration with rare‐earth activated aluminate nanoparticles (REANPs). Plasma curing was used to generate active dyeing sites on the polypropylene surface. A thin film of REANPs (2–10 nm) was deposited onto the plasma‐pretreated polypropylene surface. Various analytical techniques were applied to inspect the morphology of the REANP‐finished polypropylene fibres. The polypropylene dyeing activity was much improved after being exposed to plasma. Both photoluminescence analysis and Commission internationale de l'éclairage (CIE) laboratory coordinates proved that the polypropylene fibres exhibited a white colour in daylight and green in ultraviolet light. The thin afterglow layer immobilized onto the polypropylene surface exhibited an emission band of 524 nm upon excitation at 365 nm. The sliding angles dropped from 12° to 9°, but the contacting angles increased from 139.4° to 145.0° when the REANP ratio was raised. These findings show that REANP‐finished polypropylene had good colourfastness, antimicrobial activity, and ultraviolet light blocking. Both stiffness and permeability to air of REANP‐finished polypropylene were explored to designate excellent comfort characteristics. [ABSTRACT FROM AUTHOR]

No matter photoinduced organic radicals have been reported frequently, they are usually non‐luminescent at ambient conditions. The internal mechanism on stability and electronic transitions of photoinduced radicals, is thus crucial for the development of relevant materials. Herein, a series of photoinduced radical emission systems were developed conveniently through doping benzoic acids into the hydrogen donor polyvinyl alcohol (PVA) matrix. Visual photoinduced radical emission and photochromism could be observed on Ph‐3COOH@PVA film with the formation of cyclohexadienyl‐type structure. For the first time, radical afterglow appeared with energy transfer from triplet state. The appropriate introduction of carboxylic groups to three nonadjacent carbon atoms on the benzene ring was the best for decreasing spin population and promoting electronic transitions of the radical. This study largely expands the radical emission property from both internal mechanism and practical application. [ABSTRACT FROM AUTHOR]

In this work, H2S is decomposed with the use of a N2 microwave (MW) plasma torch at atmospheric pressure with hydrogen as the main product as well as elemental sulfur. The variation of the conversion rate of H2S into H2 is investigated with respect to various dilution ratios of H2S to N2 as the carrier gas, MW power, total flow rate, and arrangement of the cooling rods in the reaction chamber. It is experimentally found that direct cooling of the afterglow by introducing a cooling rod downstream in the reaction chamber enhances the conversion rate, and an optimum for each conversion curve is determined, which is dependent of MW power, gas flow rate, and relative distance of the cooling rod in the afterglow. [ABSTRACT FROM AUTHOR]

With the whole society's demand for intelligence, the smart highway has become the inevitable trend of road development. Luminescent road marking made of long persistent luminescent coating is a new type of functional marking that is designed with long afterglow luminescent material as the raw material and has many features such as safety, beauty and energy saving. Here, SrA12O4:Eu2+,Dy3+ green long afterglow phosphors were prepared using a high-temperature solid state method. The green phosphors obtained at 1350 °C have two traps with a shallow trap depth of 0.66 eV and a deep trap depth of 0.8 eV. The green afterglow can be seen in the dark for more than 8 h after sunlight excitation for 2 h. The green long persistent luminescent coatings were synthesized using the blending method. The uniformity of each component can be improved by adding 1.25% SiO2 into the luminescent coatings. The addition of 3.5% CaCO3 will improve the compactness of the coatings and reduce water absorption. After soaking in water for 120 h, the afterglow intensity of the coating decreases to 76% of the original, showing good water resistance. After daylight excitation in different weather conditions (cloudy, sunny, rainy), the afterglow can reach more than 5 h; therefore, it can be applied to a smart highway. [ABSTRACT FROM AUTHOR]

In the era of multi-messenger astronomy, gamma-ray bursts (GRBs) with known redshifts, especially high-redshift GRBs, are a powerful tool for studying the structure and evolution of the early Universe. We review the background, the history, and the application of measurement methods of GRB redshifts in astronomy. Based on different observation targets, two measurement methods are mainly introduced. One is on GRB afterglow, the other is on GRB host galaxy. There are various processing methods belonging to measurement methods based on afterglow, including spectral measurement method of afterglow and afterglow spectral energy distribution fitting method with improved methods. There are also numerous measurement methods based on host galaxy, such as spectral measurement method of host galaxy, template matching method of host galaxy, some automatic spectroscopic redshift measurement methods, and machine learning methods. We subsequently introduce the principles, effects, and performance of these methods. We enumerate several detection and measurement instruments, which have been used in observation. The characteristics, advantages, disadvantages, and applicability of the GRB redshift measurement methods are summarized and analyzed. Furthermore, we provide a data set of 611 GRBs with measured redshift. The data set has been collected since 1997. Analysis and statistics are presented based on this data set. We summarize the characteristics of GRBs such as location, time, and accuracy. Finally, we introduce Space-based multi-band astronomical Variable Objects Monitor (SVOM) mission dedicated to searching high redshift GRBs. We also introduce the application prospect of various redshift measurement methods in SVOM mission.

Inorganic boric acid (BA) is generally not considered an efficient afterglow material, and several groups have reported its extremely weak room‐temperature phosphorescence (RTP) in the blue spectral region. It is discovered that heat treatment of BA results in increased afterglow intensity (27‐fold increase) and prolonged emission lifetime (from 0.83 to 1.59 s), attributed to enhanced through‐space conjugation (TSC) of BA. The afterglow intensity of BA can be increased further (≈415 folds) by introducing p‐hydroxybenzoic acid (PHA), which contains a conjugated molecular motif, to further promote the TSC of the BA system. This combination results in the production of afterglow materials with a photoluminescence quantum yield of 83.8% and an emission lifetime of 2.01 s. In addition, a tunable multicolor afterglow in the 420–490 nm range is achieved owing to the enhancement of the RTP and thermally activated delayed fluorescence of PHA, where BA exerts a confinement effect on the guest molecules. Thus, this study demonstrates promising afterglow materials produced from extremely abundant and simple precursor materials for various applications. [ABSTRACT FROM AUTHOR]

The optical anti‐counterfeiting science and technology are currently restricted by the limited information loading capacity, and thus development of multi‐level and high‐security systems is urgently needed but still challenging. Herein, anti‐counterfeiting design strategies (including ASCII/5D codes and dynamic information storage) are reported by incorporation of abundant multi‐central luminescence and time‐resolved, excitation‐dependent ultralong phosphorescence. Self‐assembly of new single‐component 0D organic–inorganic metal halides (OIMHs) are facilely achieved, which exhibit divisible ultralong all‐phosphorescence, thermally activated delayed fluorescence, and single‐molecule white‐light emission, as proved by experiments and theoretical calculations. Interestingly, combing advantages of both inorganic cluster and π‐conjugation in OIMHs, the time‐dependent afterglow affords color‐variable emission in a wide wavelength range larger than 100 nm, providing extra color‐time dimensions for information encryption compared to traditional single‐color fluorescent anti‐counterfeiting. Moreover, white light‐emitting diode device is further developed to show high lighting ability for the single‐component OIMH. Therefore, this study paves an effective way to fabricate cluster‐based single‐component hybrids by equipping different emitters to confer diverse photoluminescence manners and satisfy down‐to‐earth application requirements. [ABSTRACT FROM AUTHOR]

Heavy atom effects and n-π* transitions have been frequently reported to enhance room-temperature organic phosphorescence efficiency but lead to shortage of phosphorescence lifetimes. Unlike these reported studies, we conceive the incorporation of advanced charge transfer (CT) technology to boost room-temperature organic afterglow efficiency and simultaneously maintain afterglow lifetimes. Here we design difluoroboron β-diketonate (BF2bdk) CT compounds with moderate singlet-triplet splitting energy (ΔEST) of around 0.4 eV, and relatively large spin-orbit coupling matrix elements (SOCME(S1-T1), 1–10 cm−1) to achieve efficient intersystem crossing (ISC) and moderate rates of reverse intersystem crossing (kRISC, 1–10 s−1). The advanced CT technology, which includes multiple electron-donating groups and orthogonal donor-acceptor arrangement, have been found to narrow ΔEST and enhance both ISC and RISC. Meanwhile, the organic matrices suppress nonradiative decay of BF2bdk's T1 states by their rigid microenvironment. Consequently, thermally activated delayed fluorescence (TADF)-type organic afterglow materials can be achieved with afterglow efficiency up to 83.0%, long lifetimes of 433 ms, excellent processablility, as well as advanced anti-counterfeiting and information encryption. Furthermore, with the aid of up-conversion materials and through radiative energy transfer, TADF-type afterglow materials with aqueous dispersity and near-infrared light- excitable property have been achieved, which paves the way for biomedical applications. [ABSTRACT FROM AUTHOR]

Long persistent luminescence (LPL) materials of SrAl2O4 doped with Eu2+ or Dy3+ can maintain emission over hours after ceasing the excitation but suffer from insolubility, high cost, and harsh preparation. Recently, organic LPL of guest‐host exciplex systems has been demonstrated via an intermediate charge‐separated state with flexible design but poor air‐stability. Here, we synthesized a nontoxic two‐dimensional organic–inorganic metal hybrid halides (OIMHs), called PBA2[ZnX4] with X=Br or Cl and PBA=4‐phenylbenzylamine. These materials exhibit stable LPL emission over minutes at room‐temperature, which is two orders of magnitude longer than those of previously reported OIMHs. The mechanism study shows that the LPL emission comes from thermally activated charge separation state rather than room‐temperature phosphorescence. Moreover, the LPL of PBA2[ZnX4] can be excited by low power sources, representing an effective strategy for developing low‐cost and high‐stability LPL systems. [ABSTRACT FROM AUTHOR]

Clusterization‐triggered emission is emerging as a powerful strategy leading to useful luminescence such as room‐temperature phosphoresce (CTE‐RTP), yet people's recognition on CTE‐RTP is still very limited, so that it remains challenging to achieve multicolor CTE‐RTP due to the difficulty in tailoring the clustering state of the atoms with lone pair electrons. The authors report that phosphorescence resonance energy transfer (PRET) can occur in the CTE‐RTP system, which enables fine‐tuning the color of the CTE‐RTP. Since the CTE‐RTP is a broad band in the range of 400–700 nm, and the dipole orientations are diverse in the CTE material, PRET can always occur between the CTE‐RTP and arbitrary fluorescent dyes to obtain delayed fluorescence ranging from green to near infrared. Because the lifetime of the delayed fluorescence depends on their molecular structure, dynamic afterglow can be facilely achieved in the ensemble of a PRET‐CTE‐RTP system, making it very appealing in anticounterfeiting. [ABSTRACT FROM AUTHOR]

We present the results of our analysis of multiwavelength observations for the long gamma-ray burst GRB 200829A. The burst redshift has been determined photometrically at the afterglow phase. In gamma rays the event is one of the brightest (in isotropic equivalent), erg. The multicolor light curve of the GRB 200829A afterglow is characterized by chromatic behavior and the presence of a plateau gradually transitioning into a power-law decay that can also be interpreted as a quasi-synchronous inhomogeneity (flare). We assume that the presence of a chromatic inhomogeneity in the early afterglow is consistent with the model of a structured jet. [ABSTRACT FROM AUTHOR]

Currently, extensive research activities are devoted to developing persistent phosphors which extend beyond the visible range. In some emerging applications, long-lasting emission of high-energy photons is required; however, suitable materials for the shortwave ultraviolet (UV–C) band are extremely limited. This study reports a novel Sr2MgSi2O7 phosphor doped with Pr3+ ions, which exhibits UV–C persistent luminescence with maximum intensity at 243 nm. The solubility of Pr3+ in the matrix is analysed by X-ray diffraction (XRD) and optimal activator concentration is determined. Optical and structural properties are characterised by photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) spectroscopy techniques. The obtained results expand the class of UV–C persistent phosphors and provide novel insights into the mechanisms of persistent luminescence. [ABSTRACT FROM AUTHOR]

Optically active persistent luminescent materials have attracted significant attention due to their distinctive luminescent characteristics and ability to exhibit rich circular polarization information. Despite extensive efforts to develop circularly polarized persistent luminescence (CPPL) materials using chiral molecules or polymers, fabricating CPPL materials from achiral units remains a big challenge. In this work, we introduce an efficient co-assembly strategy to create CPPL materials using entirely achiral organic molecules. The optical activities of co-assembled complexes are attributed to structural chirality, which arises from chiral nanohelices formed during symmetry breaking in the self-assembly process of C 3 -symmetric molecules. Achiral molecules with long-lasting phosphorescence can adhere to these chiral nanostructures via hydrogen bonding, and during the drying phase, form nanocrystals that align along helical fibers, resulting in circularly polarized, long-lasting phosphorescence. Enhanced CPPL efficiency, ranging from blue to yellow with a dissymmetry factor over 1.2 × 10−2 and lifetime of up to 0.6 s at room temperature, is achieved through hydrogen bonding driven co-assembly. Additionally, the CPPL spectra of these co-assemblies are captured using a homemade time-resolved circularly polarized long afterglow detection platform. This study not only presents a new approach for the high-efficiency design of CPPL materials from achiral building blocks but also significantly broadens the research possibilities in real-time CPPL analysis, offering a horizon in the exploration of CPPL materials. [Display omitted] • Supramolecular nanomaterials with CPPL are constructed from completely achiral building blocks. • A homemade detection platform can eliminate the influence of fluorescence on CPPL, enabling systematic exploration of CPPL. • The detection platform is adaptive to almost all the CPPL materials for capturing circular polarization information throughout the entire process. [ABSTRACT FROM AUTHOR]

A state-of-the-art semi-analytic gamma-ray burst (GRB) afterglow model with synchrotron self-Compton (SSC) emission has been applied for the first time for parameter inference using real GRB data. We analyzed the famous GRB 190114C as a case study. GRB 190114C, characterized by its long duration and high luminosity, was observed by many ground-based and orbiting telescopes spanning a wide range of electromagnetic wavelengths, from radio to GeV gamma rays. We used two advanced algorithms for inference: a nested sampling algorithm called UltraNest and an MCMC algorithm emcee. Evoking the standard afterglow model, the inference result and the best-fit values lead to an initial bulk Lorentz factor (a rough estimate of Γ=526), which aligns with the values often seen in GRBs identified by the Fermi-LAT instrument. Similarly to the best-fit values of other studies in the literature, the derived values of microphysical parameters, the circumburst density, and the kinetic efficiency are consistent with those found after modeling the multi-wavelength observations in GRB 190114C. We show that the SSC from the forward-shock region can only describe the highest-energy photons above a few GeVs.

In the exciton model of organic compounds proposed by Kasha, energy levels of T1 states are insensitive to microenvironment because of negligibly small transition dipole moments of T1 states. This phenomenon of T1 energy conservation holds true in most organic systems. Here a serendipitous finding of a twisted organic phosphor that breaks T1 energy conservation in dopant‐matrix phosphorescence systems is reported. Specifically, the twisted phosphor exhibits distinct phosphorescence colors and T1 energy levels when doped into different organic matrices under ambient conditions. Time‐dependent density functional theory calculations reveal that, when the twisted phosphor is in its freely rotating form, the increase of twisted angle leads to the increase of its T1 energy level. After being planarized by alkyl cyclization, the phosphor shows the recovery of T1 energy conservation. Owing to its sensitive T1 level, the twisted phosphor functions as label‐free and visual probe for direct observation of polymer phase separation. [ABSTRACT FROM AUTHOR]

A comparative study on the radioluminescence properties of Ce-doped SrAl2O4 single crystal and translucent ceramic was performed. The transmittance of the synthesized ceramic is 20-30% in the visible region. Both samples exhibit photo- and radioluminescence with a broad emission peaking at 380 nm. The decay curves are fitted by a single exponential decay function with decay time constants of 30-50 ns, consistent with the typical value of the emission for the 5d-4f transitions of Ce3+. From the pulse height spectra measured under 241Am γ-ray (59.5 keV) irradiation, the scintillation light yields are 17000 ph/MeV for the single crystal and 6100 ph/MeV for the synthesized ceramic. The scintillation light yield and afterglow of the present samples show a negative correlation. [ABSTRACT FROM AUTHOR]