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Here, we have developed a novel ultra long ultraviolet-A afterglow material CaMgGeO 4 : Bi3+, which shows more than 24 h UVA afterglow emission peaked at 346 nm. The crystal structure shows that the prepared sample is a pure phase with an orthogonal system of Pmnb space group. The composition of valence band and conduction band was analyzed by the density of states, which reveals that the bandgap of the CaMgGeO 4 matrix is 3.69 eV. The photoluminescence spectrum of the sample consists of a broadband in the 320–400 nm UVA region, which belongs to the 3P 1 → 1S 0 electron transition of Bi3+. More importantly, under the excitation of ultraviolet lamp for 3 min, CaMgGeO 4 : Bi3+ exhibited an UVA ultra long persistent luminescence (LPL) with a duration of more than 24 h, which afterglow emission intensity still reaches 1500 cps and is about 6 times of the background intensity. In addition, the UVA emission of CaMgGeO 4 : Bi3+ after 13 h day can be repeatedly by short periods of low-energy light sources stimulation. The thermoluminescence analysis indicates that the presence of shallow and deep traps is responsible for excellent UVA-LPL and photo-stimulate luminescence (PSL). The excellent LPL and PSL properties can prompt CaMgGeO4: Bi3+ phosphor to be widely used in the field of photodynamic therapy. [ABSTRACT FROM AUTHOR]

A binary composite ceramic Na 0.5 Bi 0.5 TiO 3 :0.002 Er-0.3CaTiO 3 :0.003 Pr (NBT:Er-0.3CT:Pr) was fabricated by a conventional solid state reaction route. The effect of sintering temperature on the microstructure and phase structure of the ceramics has been investigated. And the basic electrical properties such as dielectric properties and ferroelectric performances of the ceramics were examined. Macro long-ranged ferroelectric order cannot be induced via electric field in the composite ceramics. And under local electric field using PFM, obvious ferroelectric switching is identified in the ceramics. Furthermore, the up-conversion luminescence, photochromic reaction, and luminescence modulation have been achieved in the ceramics. Additionally, photo-stimulated luminescence and thermal luminescence are obtained. The present study indicates that optical properties are tightly related to the sintering temperature. The prepared ceramic NBT:Er-0.3CT:Pr owns a piezoelectric performance and multi luminescence properties, which can widen the applications of ferroelectric ceramics. [ABSTRACT FROM AUTHOR]

When a radiological and nuclear (R/N) emergency occurs, the categorization of individuals into those who are unaffected and those requiring medical intervention is a high priority. At times, a professional dosimeter is not available and therefore some common belongings may be used as fortuitous dosimeters. The preparation of these objects for the measurement should be such as to give the most accurate and precise results. This paper focused on the Photo-Stimulated Luminescence (PSL) response of salty crackers confronts the problem of sample preparation (mass, grain size), dose response and signal stability. The dose response was determined for doses up to 5 Gy, which allowed the calculation of the limit of detection. Additionally, the signal stability was investigated for samples irradiated with 0.3 and 3 Gy. The observed decrease of the signal does not prevent the detection in the dose range typical for R/N emergency. The main dosimetric characteristics were investigated by using two different models of PSL readers equipped with single (infrared) or double (infrared, blue light) stimulation. The results indicated that the limit of detection can be improved by applying blue light stimulation. Moreover, strong correlation of the measurements performed in the two different instruments, as well as the rapidity of the analysis and the simplicity of the operations, suggest that this method can be suitable for a rapid radiation triage of a large number of civilians in a mass casualty event. The study was simultaneously conducted by two laboratories (Ruder Bošković Institute, RBI, Croatia and Istituto Superiore di Sanità, ISS, Italy) involved in the BioPhyMeTRE project (grant No. G5684) supported by NATO Science for Peace and Security Programme.

The aim of this work was to verify the applicability of the European Standard EN 13751, based on Photo-Stimulated Luminescence (PSL) and the European Standard EN 1788, based on Thermoluminescence (TL), for the detection of irradiation in plant food supplement (PFS) ingredients, nuts and fresh fruits with health benefits. In particular, in this work, herbal ingredients (Camellia sinensis , Ginkgo biloba , Glycine max , Silybum marianum , Vaccinium myrtillus), almonds, hazelnuts, peanuts, pistachios, walnuts and fresh blueberries, papaya and mango, were analyzed by both stimulated luminescence methods. To verify the reliability of the methods in detecting the treatment over time, the analyses were replicated after irradiation within the product shelf life. The PSL screening method allowed to correctly identify blueberries, nuts and raw materials of PFS but failed with dried herbal extracts, mango and papaya, due to their low content of silicates. To validate the procedure elaborated during the preliminary study, blind tests, involving several national laboratories of the official control, were organized. The tests confirmed the limits in detecting dried extracts, mango and papaya by PSL technique. TL method resulted suitable as a confirmatory method for all the matrices of the study. • PSL based method came out suitable for nuts and PFS raw materials. • Dried extracts and fresh mango and papaya came out as critical matrices for PSL. • TL method is suitable for PFS ingredients, nuts, blueberries, mango and papaya. • Fading of the signal was observed but even so it was possible to detect the samples. [ABSTRACT FROM AUTHOR]

Photo-stimulated luminescence materials have attracted widely attention for their potential application of in vivo imaging owing to the rewritable properties and the ability of immobilizing carriers at room temperature. Recently, photo-stimulated luminescence phosphors validated at a higher temperature than the room temperature are urgently needed for the fact that endotherms generate heat to maintain their body temperature which is typically above their surroundings. Therefore, it is critical for the practical application of in vivo imaging, especially with clinical significance. Herein, BaZrGe 3 O 9 doped Pr3+ ions developed in this work, possesses a successive deep defect structure preventing the thermal fading of carriers ranging from 303 to 323 K. Furthermore, the penetration depth of the designed red photo-stimulated luminescence and the chemical stability of BaZrGe 3 O 9 : Pr3+ for in vivo imaging are investigated in detail. Our results demonstrate that the developed phosphor is an excellent candidate for long-term in vivo imaging application. • The photo-stimulated luminescence property are maintained at high temperature. • The photo-stimulated luminescence have excellent penetration in biological tissues. • The phosphor displays outstanding physical-chemical stability. [ABSTRACT FROM AUTHOR]

Up-conversion persistent luminescence (UCPL) nanoparticles have captured tremendous attention due to their unique optical operating performance such as the absence of auto-fluorescence and the charging capacity of near-infrared (NIR) light. However, the weak afterglow intensity as well as low duration limits their practical applications including multimode anti-counterfeiting and biological imaging, etc. Herein, typical green persistent luminescence (PersL) and photo-stimulated luminescence (PSL) of Zn 2 GeO 4 :Mn2+ phosphors were enhanced via non-equivalent Li+ co-doping, in which the preferred site selection of Mn2+ and Li + have been verified by using the first-principles theory. The possible luminescent enhancement mechanisms were proposed based on improving the oxygen vacancy density and promoting the formation of Mn4+ defect energy level in bandgap structure by non-equivalent doping of Li+. Interestingly, UCPL of Zn 2 GeO 4 :Mn2+,Li + can be achieved after charging of Vis to NIR light. It is worth noting that this UCPL can be further enhanced by the sensitization of NaYF 4 :Yb,Tm nanoparticles via simply mixing Zn 2 GeO 4 :Mn2+,Li+ and NaYF 4 :Yb,Tm under 980 laser stimulation. As a result, Zn 2 GeO 4 :Mn2+,Li+ phosphor exhibits the enhanced quintuple-mode luminescence including photoluminescence, PersL, PSL, photo-stimulated persistent luminescence and UCPL. In particular, the achieved NIR rechargeable UCPL hybrid phosphors exhibit enormous potential for higher order anti-counterfeiting and rewriteable data encryption and decryption applications. • Green PersL and PSL of Zn 2 GeO 4 :Mn2+ phosphors were enhanced via non-equivalent Li+ co-doping. • The possible luminescent enhancement mechanisms were proposed. • UCPL of Zn 2 GeO 4 :Mn2+,Li+ can be achieved after charging of Vis to NIR light. • The UCPL can be further enhanced by the sensitization of NaYF 4 :Yb,Tm nanoparticles. • NIR rechargeable hybrid phosphors exhibit enormous potential for anti-counterfeiting and rewriteable data encryption. [ABSTRACT FROM AUTHOR]

Korean citrus fruits (Jinjihyang and Chunggyun) were treated with electron beam (e-beam) at phytosanitary irradiation doses of 0, 0.4, and 1 kGy, and their irradiation status was screened after storage for 0, 10, and 20 days. Because of the inherent limitations of photo-stimulated luminescence (PSL), the first PSL measurement (PSL1) was not sufficient to distinguish the irradiated samples from the non-irradiated controls. The calibrated PSL approach clearly distinguished the e-beam-irradiated samples from the control based on PSL ratio (PSL2/PSL1): > 10, non-irradiated; < 10, irradiated. In addition to PSL, electronic-sensing techniques (E-tongue and E-nose) clearly discriminated the irradiated Jinjihyang and Chunggyun fruits samples from their non-irradiated counterparts based on principal component analysis of taste attributes and volatile patterns. The quantitative analysis of volatile in irradiated citrus fruits showed that limonene was present at the highest concentration among all the volatiles from peels, and significant dose-dependent decreases were observed in both citrus varieties (p < 0.05). Limonene from the irradiated pulps showed a dose-dependent increase on day 0. [ABSTRACT FROM AUTHOR]

A novel green-emitting phosphor Ba 2 Ga 2 GeO 7 : Tb 3+ , Bi 3+ was successfully synthesized by solid-state reaction. The photoluminescence (PL), photo-stimulated luminescence (PSL) and long persistent luminescence (LPL) were investigated in detail. After pre-irradiation upon UV light, the PSL spectrum of Ba 2 Ga 2 GeO 7 : Tb 3+ , Bi 3+ exhibits peaks centered at 493, 547, 589, and 627 nm under excitation at 980 nm, ascribed to the transitions of 5 D 4 → 7 F j (j = 3, 4, 5, 6) by tunneling process. While PL spectrum exhibits peaks related to the transitions of 5 D 3 , 5 D 4 → 7 F j (j = 3, 4, 5, 6). Thermo-luminescence (TL) curve shows that a large amount of traps can be in Ba 2 Ga 2 GeO 7 : Tb 3+ by induced Bi 3+ , leading to the improvement of PSL spectra performance. These findings open a vista of possible avenues for the understanding of the PSL process. [ABSTRACT FROM AUTHOR]

Bi 3+ -activated phosphor with ultraviolet-visible persistent luminescence and photo-stimulated luminescence is synthesized via high temperature solid phase reaction. This phosphor shows a broad emission band from 300 nm to 700 nm, a bright persistent luminescence over 12 h after ceasing the excitation and the photo-stimulated luminescence under the excitation of visible to near-infrared light. This paper reports that the operational waveband of long persistent phosphor, CaZnGe 2 O 6 : Bi 3+ , has been extended into the short-wavelength spectral region. [ABSTRACT FROM AUTHOR]

The formation of suitable defects levels is crucial to the optical performance of the electron trapping materials which provide a wide range of applications from the initial civil uses to life sciences, energy and environmental engineering. SrGa 2 O 4 , possessing a one-dimensional chain structure of cations along a crystal direction, exhibits a self-activated blue long persistent luminescence (LPL) related to the intrinsic defects. Different trap depths are generated forming a successive defect structure in this three-dimensional framework of SrGa 2 O 4 containing channels occupied by Sr 2+ when Tb 3+ ions are introduced. The captured carriers in shallow traps are spontaneously released at room temperature and recombine in the luminescence center of Tb 3+ , eventually causing characteristic emission of Tb 3+ . The deeper traps are critically important to prevent the thermal fading of carriers at room temperature, therefore, LPL is achieved in SrGa 2 O 4 :Tb 3+ phosphor at 328 K. Furthermore, a photo-stimulated luminescence (PSL) originated from Tb 3+ ions is realized in SrGa 2 O 4 :Tb 3+ phosphor induced by 980 nm laser diode with the releasing of the carriers trapped in the deeper traps at room temperature. Our results infer that the existence of a successive defect structure with multiple traps for the incorporation of the shallow and deep ones is conducive to the thermal stability of SrGa 2 O 4 :Tb 3+ phosphor, which could provide a potential application in a rigorous environment with a higher thermal energy than the room temperature, such as solar energy utilization, and in vivo-imaging. [ABSTRACT FROM AUTHOR]

Lanthanide-doped oxide photo-stimulable (PS) phosphors (C12A7:Tb 3+ ) with different encaged anions (O 2− , H − , OH − and e − ) have been prepared by a combustion method in combination with treatment under different conditions. Electron spin resonance (ESR) and Fourier transform IR (FTIR) transmittance data confirm the existences of encaged electrons, O 2 − (indicating the existence of encaged O 2- anions) and OH − anions in C12A7:Tb 3+ . PS luminescence, thermoluminescence (TL), X-ray storage properties and luminescent kinetics analysis show that the more encaged OH − anions appear in C12A7, the shallower the depths of the two deeper traps (E trap1 = ∼0.72 eV and E trap2 = ∼0.95 eV), the smaller the glow-peak intensity ratio (I trap2 /I trap1 ), the shorter the X-ray storage time and the lower the quality of X-ray imaging become. Our results suggest that, among all the anions, encaged OH − anions in C12A7:Tb 3+ play a key role in influencing X-ray storage properties of PS phosphors. High-quality X-ray image with a resolution of ∼15 line pairs per mm (lp/mm) has been obtained by reducing encaged OH − anions in PS phosphors. The C12A7:Tb 3+ PS phosphor is a potential candidate material for computed radiography system and erasable/rewritable optical memory media. [ABSTRACT FROM AUTHOR]

A series of Ba 1− x Ca x S: 2%Yb 2+ ( x =0, 0.1, 0.3, 0.5, 0.7, 0.9, 1) persistence phosphors were prepared via a conventional solid state reaction method under H 2 reducing atmosphere. Fluorescence, phosphorescent and near-infrared photo-stimulated spectra were presented at room temperature. The obtained data indicated that the red persistent luminescence can be lengthened by introducing impurity metal cation. Moreover, the persistent luminescence can be effectively released under the excitation of 980 nm LED. In consideration of the high transmittance of red light as well as near-infrared lights in the organism, Ba 1− x Ca x S: 2%Yb 2+ phosphors have potential application in fluorescence bio-imaging. [ABSTRACT FROM AUTHOR]

Photoluminescence (PL), photo-stimulated luminescence (PSL), and thermoluminescence (TL) properties of a Ce-doped CaB 2 O 4 crystal were studied. The Ce-doped crystal was prepared by the simple solidification method using a Pt crucible under nitrogen atmosphere. A PL emission band in the 350–370 nm wavelength range was obtained under excitation at 325 nm owing to the 5d (t 2g )–4f ( 2 F 5/2 , 2 F 7/2 )-allowed transition of the Ce 3+ emission center. The fluorescence quantum efficiency and the decay time of Ce 3+ were estimated to be about 70% and 29 ns, respectively. The 5d–4f emission band of Ce 3+ also appeared in the 350–370 nm wavelength range in the TL and PSL spectra. Good linear TL and PSL responses were observed in the 1–1000 mGy and 1–10,000 mGy X-ray dose range, respectively. [ABSTRACT FROM AUTHOR]

The red persistent and photo-stimulated luminescent (PSL) nitride phosphor, SrCaSi 5 N 8 : Eu 2+ , Tm 3+ solid solution, had been synthesized through conventional high temperature solid-state reaction. The SrCaSi 5 N 8 : Eu 2+ , Tm 3+ phosphor shows strong photoluminescence (PL) and weak PSL ( λ em = 647 nm), both originating from the 4f 6 5d–4f 7 transition of Eu 2+ . Thermoluminescence (TL) glow curves measured at various stimulating conditions (UV excitation, in dark, laser stimulation after UV irradiation) show the same peak positions at 345 K and 360 K but great differences in the intensities. The afterglow decay curve presents excellent long-lasting red phosphorescence with a decay time of 30 min (⩾0.32 mcd/m 2 ) after turning off the activating light. Moreover, the laser stimulated luminescence spectra, which feature sharp rising and falling edges (monitored at 647 nm) as the infrared laser diode (980 nm) excitation was turned on and off periodically, exhibit interesting rapidly responsive, erasable and rewritable abilities. [ABSTRACT FROM AUTHOR]

In this work, a novel SrS: Yb 2+ long persistent luminescence (LPL) phosphors were prepared by a solid state reaction in a reduce atmosphere. Meanwhile, the phosphors showed the characteristic of photo-stimulated luminescence (PSL). The photoluminescence (PL) properties, long afterglow curve as well as PSL of the as-prepared phosphors were systematically investigated. The results indicate that the emission spectrum covers from 550 nm to 700 nm with a maximum at 605 nm. When excited by 465 nm light as well as 980 nm LD, red LPL was observed in this phosphor. The red LPL and PSL suggest that SrS: Yb 2+ has good prospect for application. [ABSTRACT FROM AUTHOR]

Abstract: A large enhancement of photo-stimulated luminescence by co-doping Tm3+/Dy3+ in α′-Sr2SiO4 was observed, upon the infrared (IR) stimulation at 980nm after pre-exposure with Ultraviolet (UV) light. More interestingly, the color of PSL changes from green to yellow with substituting Dy3+ with Tm3+. The results indicate that co-doping of Tm3+ generates a large number of traps peaking at 400K, which able to immobilized the carriers permanently at room temperature and is more sensitive to IR light than other traps. It induced the redistribution of trap centers, especially around the emission center Eu2 which located at another inequivalent site. [Copyright &y& Elsevier]

Er3+ and Sm3+ ions were co-doped in Sr 2 SnO 4 : x Er3+/Sm3+ ceramics to achieve the integration of photo-stimulated luminescence (PSL), thermal-stimulated luminescence (TSL) and photochromism (PC) in one single material. The effect of doped Er3+ content on the microstructure, PC, PSL and TSL of the ceramcis has been investigated. It is found that moderate Er3+ content (x ≤ 0.003) could enhance PC, photoluminescence and TSL performance of the ceramics. The PSL and TSL are greatly depressed when x ≥ 0.005. This variation is caused by the change of kinds of formed defects. In addition, we have proposed a new method for optical information storage using the PSL as the optical signal, in which up-conversion luminescence from Er3+ is the reference signal. This strategy could prevent the occurring of error signal. A simple mechanism on the luminescence modulation, PC, PSL and TSL is proposed basing on the defect chemistry. The application demonstration shows the ceramics' potential in optical devices due to their multi-functional optical properties. • PC, PSL and TSL properties of Er3+/Sm3+ co-doped Sr 2 SnO 4 ceramic were investigated. • PSL occurs when 980 nm stimulated, with three peaks located at 582 nm, 622 nm and 672 nm. • The method using PSL signal can avoid the influence of original signal. • Moderate Er3+ concentration (x ≤ 0.003) could enhance PC, PL and TSL performance. • A new method for optical information storage based on PSL signal and UC signal has been proposed. [ABSTRACT FROM AUTHOR]

Highlights: [•] White-light long persistent luminescence in CSSO:Dy3+ was observed. [•] White-light photo-stimulated luminescence in CSSO:Dy3+ was observed. [•] A model for energy storing and releasing through the IR irradiation was presented. [Copyright &y& Elsevier]

Abstract: Hydrogen trapping and its interaction with defects in Li2TiO3 and Li2ZrO3 that were irradiated with hydrogen isotopes and exposed to air were investigated using ion beam techniques and photo-stimulated luminescence (PSL) measurements. During irradiation with 10keV H2 +, the incident hydrogen was trapped in Li2TiO3 at the end of its trajectory until the local concentration reached 12.5at.%, whereas an increase in the hydrogen retained in Li2ZrO3 was observed at a considerably greater depth as compared to the projected range. A broad PSL emission with two peaks at around 2.8 and 3.1eV was observed under irradiation of Li2ZrO3 with 5.17eV light. The PSL intensity of the band at 2.8eV showed a remarkable decrease as compared to the peak at 3.1eV upon irradiation with 10keV D2 +. The results of isochronal annealing subsequent to irradiation showed that the recovery of the luminescence intensity in the 2.8eV luminescent centers and release of hydrogen occurred in the same temperature range of 350–450K. In addition, the formation of a Li2CO3 layer at the surface of Li2TiO3 and Li2ZrO3 following exposure to air was subject to the humidity conditions and was considered to play an important role in the dissociation of water vapor and hydrogen trapping beneath the reaction layer in Li2TiO3 and Li2ZrO3. [Copyright &y& Elsevier]

Abstract: A heavy-ion microbeam system for cell irradiation has been developed using an accelerator at Kyoto University. We have successfully developed proton-, carbon-, fluorine- and silicon-beams in order to irradiate a micro-meter sized area with ion counting, especially single ion irradiation. In the heavy-ion microbeam system, an imaging plate (IP) was utilized for beam diagnostics on the irradiation. The IP is widely used for radiography studies in biology. However, there are a few studies on the low linear energy transfer (LET) by single ions, i.e., low-intensity exposure. Thus we have investigated the energy response for the IP, which can be utilized for microbeam diagnostics. [Copyright &y& Elsevier]

Abstract: We compared the photo-stimulated luminescence (PSL) process of storage phosphor KCl:Eu under the irradiation of X-ray, 2.0MeV H+ ions and 2.0MeV He+ ions. The purpose of the irradiation of H+ and He+ ions was to mimic the irradiation effects of neutrons. In each case, it was revealed that F-centers were involved in the PSL process. We observed an entirely different fluence-dependent PSL behavior between the X-ray and the ion irradiation, whereas the behavior of the F-center absorption was quite similar. This difference was due to the different yields of the trapping sites for the electrons liberated from the F-centers, and the difference in the yield was ascribed to the difference in the excitation density. This result clearly indicated a marked difference in the PSL process under X-ray and neutron irradiations and indicated that the analysis of the PSL process under ion irradiation is highly important for the application of PSL phosphors to neutron radiography. [Copyright &y& Elsevier]

Abstract: Photo-stimulated luminescence (PSL) and thermoluminescence (TL) analyses were done to screen or identify irradiation treatment of ostrich, duck, hen and quail eggs. These eggs were gamma-irradiated at 0, 1, 2 and 3 kGy and the eggshells were used for PSL and TL analyses in a powdered form. The PSL results showed that all the non-irradiated control samples had photon counts (PCs) less than the lower threshold value (700counts/60s). Some of the irradiated samples like ostrich and duck, however, showed PCs higher than the upper threshold value (5000counts/60s), and the other irradiated samples were between the lower and upper values (700–5000counts/60s). Photon (PCs) less than the lower threshold value (700 counts/60s). Although the TL glow curves which originated from the calcite mineral present in eggshells, which were confirmed by X-ray diffraction spectroscopy. The intensities of the first glow curves (TL1) obtained from the egg shells were less intense as compared to that of quartz or feldspar that are usually present on the surface of the food as contaminants. The intensity and shape of the first glow curve (TL1) as well as the glow curve ratios (TL1/TL2) based on a normalization step, enabled discrimination between the control and irradiated eggshells by using natural bio-inorganic minerals. [Copyright &y& Elsevier]

Abstract: Gamma-irradiated NaCl samples of different origin were studied with the aim to find a reliable, easy-to-use, low-cost standard for the PSL technique, an increasingly used screening method for irradiated food identification. Five different natural salt types (rock and sea salts) purchased in the local markets were studied along with a laboratory-grade NaCl. High sensitivity and reproducibility of the PSL response are good properties of salt, but the pronounced fading of the signal may be a severe limitation of its use as a reference material. The high sensitivity along with the linear dose dependence of the PSL response opens up the interesting possibility of salt as suitable material for retrospective and environmental dosimetry, especially in the case of accidental irradiation or malevolent use of ionizing radiation. Again, the extreme sensitivity of the PSL signal to light and the pronounced fading must be considered limiting factors, and further basic research is required before practical applications of salt be feasible. [Copyright &y& Elsevier]

Abstract: We report the results from photo-luminescence (PL) measurements on single crystal RbCdF3 doped with up to 1% Mn2+, before and after X-ray and deep UV irradiation. The intensity of the Mn2+ PL emission at 560nm increases with increasing X-ray or UV (<270nm) dose. A broad PL excitation peak centered near 300nm and extending from 280nm to 420nm occurs after irradiation. The PL intensity excited by this broad band is observed to increase with increasing radiation dose, and no significant decrease in the PL intensity is observed after 2weeks. High intensity bleaching in the wavelength range from 280nm to 420nm reduces the PL emission to the original low pre-irradiated level. These observations suggest that RbCdF3:Mn2+ has potential as a dosimeter for X-rays and deep UV wavelengths less than 270nm. We find that the PL intensity systematically increases with increasing Mn2+ concentration and there is no evidence of saturation for up to 1% Mn2+. This indicates that higher sensitivity could occur with even higher concentrations of Mn2+. [Copyright &y& Elsevier]

Abstract: The structural integrity of the thermally grown oxide (TGO) in the EB-PVD/(Ni, Pt)Al thermal barrier coatings was examined using photo-stimulated luminescence piezo-spectroscopy (PLPS). PLPS spectra exhibiting both a high stress component and a low stress (or stress-free) component were observed during thermal cycling (i.e. bimodal luminescence). The fraction of bimodal spectra increases initially, then decreases, and increases again when close to failure. It is shown that the bimodal luminescence originates from stress relaxation caused by localized damage. It is proposed that the initial increase of bimodal luminescence is related to cracking caused by the volume change associated with the phase transformation of TGO from θ to α-Al2O3; whereas, the increase at the final stage is due to TGO cracking and spallation. Area stress maps show the gradual accumulation of damage and indicate that PLPS is a useful tool for detection of the initiation and progression of TBC spallation. [Copyright &y& Elsevier]

Abstract: The excellent long afterglow phosphor Sr2MgSi2O7:Eu2+,Dy3+ with the blue light and (Sr,Ca)MgSi2O7:Eu2+,Dy3+ emitting blue–green afterglow for more than 20h under the UV excitation were prepared. The trap states in the samples are studied by thermoluminescence (TL) and photo-stimulated luminescence (PSL). The results of TL and PSL exhibit plenty of traps which are responsible for the long afterglow. TL study shows that a broad band appears at 330 and 357K for (Sr,Ca)MgSi2O7:Eu2+,Dy3+ with the thermal depth of trap ETL = 0.66eV and for Sr2MgSi2O7:Eu2+,Dy3+ with the thermal depth of trap ETL = 0.75eV, respectively. PSL spectra reveals that the trapped carries also can be released by optical stimulation with the EPSL = 1.56–1.94eV. The relation between TL and PSL can be explained by the configuration coordinate mode. [Copyright &y& Elsevier]

The turbidity, photoluminescence, and photo-stimulated luminescence (PSL) of fluorozirconate glass containing barium chloride nano- and micro-crystals have been measured for samples prepared by isochronal (70 min) annealing over a temperature range of 220–283°C, and correlated with the microstructure as determined by X-ray diffraction measurements. Crystallization of hexagonal phase barium chloride commences at around 220°C, but until 275°C the material retains excellent transparency although it displays negligible PSL. Between 275°C and 277°C, the hexagonal phase converts to the orthorhombic phase, the transparency abruptly decreases, and the PSL rises to a value of around 13% of that found for the commercial storage phosphor BaFBr:Eu. For a slightly higher temperature of 280°C, new phases appear which correspond to the onset of bulk crystallization, and at 283°C the relative PSL rises to 33%, while the transparency falls further. The trade-off between optical transparency and PSL over this narrow temperature window for X-ray imaging plate applications is briefly discussed. [Copyright &y& Elsevier]

The development of transparent glass ceramics as X-ray storage phosphors and their advantages over their crystalline counterparts are briefly reviewed. Measurements of conversion efficiency, stimulation efficiency, storage times, and optical transparency are reported for the particular case of europium-doped fluorobromozirconate glass, in which rubidium and lithium replace the usual sodium component fraction. Annealing at 280 °C converts the as-prepared glass into a glass–ceramic which contains Rb2BaBr4 and RbBa2Br5 nano- and micro-crystallites. Only the RbBa2Br5 structure shows significant photo-stimulated luminescence after X-irradiation, and the maximum storage phosphor efficiency is 8% of that for the standard commercial storage phosphor BaFBr:Eu. [Copyright &y& Elsevier]

Photoluminescence (PL), photostimulated luminescence (PSL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) studies were carried out on LiYF4:U4+ and pure LiYF4 crystals. The PL and EPR investigations have identified the presence of Eu3+, Tb3+ and Gd3+ ions in both of these crystals possibly due to their existence in the starting materials. The luminescence observed during afterglow, PSL and TSL revealed that emission occurs at wavelength positions 382, 413, 437 and 544 nm, which are characteristic of Tb3+ ions. The present investigations using PSL and TSL in combination with PL studies before and after gamma irradiation have revealed that selective energy transfer to Tb3+ ions occurs during electron–hole recombination processes like PSL and TSL. Even though other luminescent ions (U4+ and Eu3+) are present in the system and U4+/U3+ ions are participating in electron capture/release processes, the selective energy transfer results in Tb3+ ions acting as luminescence centers. [Copyright &y& Elsevier]

Photo-stimulated luminescence Piezo-spectroscopy (PLPS) is being developed as a non-destructive technique for thermal barrier coatings (TBC). In this study, the evolution of photo-stimulated luminescence with thermal cycling was systematically investigated from the thermally grown oxide (TGO) in a production TBC, which consists of an electron beam physical vapor deposited (EB-PVD) 7 wt.% Y2O3–ZrO2 top coat, a grit blasted (Ni,Pt)Al bond coat and a CMSX-4 superalloy substrate. The change of compressive stress in the TGO layer on the bond coat with thermal cycling was calculated from the wavelength shift of the luminescence spectra. The compressive stress increased from 1.0–2.2 GPa in the as received state to 2.8–3.3 GPa at 10 cycles, then gradually decreased to 1.2–1.9 GPa until 500 cycles and remained at this level until TBC spallation. Other fluorescence spectra characteristics, such as the width of R1 and R2 peaks and their relative intensity, were also evaluated. These PLPS measurements on TBCs with grit blasted bond coats are compared with previous measurements on similar TBC system but with non-grit blasted bond coats. It is concluded that the initial increase in stress is associated with the formation of a continuous oxide layer. The lower stress of the specimens with the grit blasted bond coats compared to that of the as-coated bond coats is associated partly with the greater surface roughness. And the fast decline in compressive stress is the result of bond coat surface rumpling facilitated by the initially rougher surface. The lifetime of the TBCs with grit blasted bond coats varies over a narrow range, 600–750 cycles with an average of 675 cycles, which is related to their consistent bond coat surface roughness. [Copyright &y& Elsevier]

The distinctive features of photo-stimulated luminescence (PSL) of the X-ray storage phosphor BaFBr:Eu+2 are interpreted on the ground of a monomolecular electron–hole recombination mechanism. The thermal enhancement of PSL intensity is explained by taking into account a three level scheme for F(Br−) centres. A comparison with data on PSL intensity versus temperature reported in literature is presented. [Copyright &y& Elsevier]

The time evolution of PSL in certain photo stimulable phosphors has been studied for several storage temperatures ranging from 0°C to 60°C and for time periods from 0.03 to approximately 500 h after irradiation. The experiments were carried out using commercially available BaFBr:Eu2+ phosphors: BAS-UR and BAS-TR (Fuji Film Co.).The fading curves obtained after irradiation with a 244Cm source were analyzed by applying Arrhenius’ equation to the experimental results, the same method reported previously (). An improved equation, which is a function of elapsed time (t) and absolute temperature (K), was proposed. Comparison of the data of the experiment and calculated results based on a model consisting of four components for BAS-UR and five components for BAS-TR showed excellent agreement at all temperatures and over all time periods.The formula was also confirmed as giving the proper calculated photo-stimulated luminescence (PSL) corresponding to the temperature changes between the elapsed times, and showed good consistency with the experimental results. [Copyright &y& Elsevier]

• PL modulation, PC, PSL and TL properties are realized in Sr 2 SnO 4 :Sm3+ material. • The PL modulation ratio reaches an infinite value ∞ using the PSL mode. • The mechanisms of PC, PSL and TL are analyzed using XPS and EPR. • The material can be used in anti-counterfeiting or optical information storage. Reversible luminescence modification has received considerable interest due to its potential applications in optical storage technology and high-sensitivity optical switches. However, there is no any report that multi-mode luminescence modification behavior can be achieved in one material so far. In this study, a novel multifunctional luminescence phosphor Sr 2− x SnO 4 : x Sm3+ has been developed. Photoluminescence, photoluminescence modulation associated with the photochromism reaction, photo-stimulated luminescence, thermoluminescence are realized in one single ceramic material Sr 2− x SnO 4 : x Sm3+. The optimized photoluminescence modulation ratio based on the photochromism reaction reaches 72.2%. Based on the photo-stimulated luminescence, the photoluminescence modulation ratio reaches an infinite value ∞, which provides a different approach for optical storage and can avoid the bit error in information storage. In addition, the mechanisms of photoluminescence modulation, photo-stimulated luminescence, thermoluminescence are analyzed. The diverse luminescence properties in Sr 2− x SnO 4 : x Sm3+ are tightly related to the formed defects induced by Sm3+ doping. The high integration level for fluorescence performances can widen the application of activator-doped oxides. [ABSTRACT FROM AUTHOR]

Abstract: The optical storage properties of CSSO:Dy as a function of the dysprosium concentration were investigated. Following 980nm excitation, the photo-stimulated luminescence of white-light was first observed in CSSO:Dy. TL curves revealed that there existed three types of trap (T 1, T 2, T 3) in CSSO:Dy corresponding to the temperature bands, located at 300, 424 and 525k, respectively. With increasing dopant contents, the amount of the deep traps (T 2 and T 3) increases, whereas the shallow traps concentration decreases. The results demonstrate that the optical storage ability of CSSO:Dy is enhanced with increasing Dy3+ contents at room temperature. [Copyright &y& Elsevier]

The persistent phosphor Y 3 Ga 5 O 12 : 0.5%Cr3+ (YGG:C) and Y 3 Ga 5 O 12 : 0.5%Cr3+, 0.5%Si4+ (YGG: CS) were synthesized by traditional solid-state reaction. Y 3 Ga 5 O 12 was employed as a host to take advantage of its abundant intrinsic traps. Moreover, Si4+ dopant was introduced to precisely tailor the trap distribution so that the initial persistent brightness of YGG: CS is around 7 times higher than that of YGG: C. The photo-stimulated traps were firstly found in YGG: CS, and the effective number of photo-stimulation was confirmed to be several hundreds. The broad emission band (650–950 nm) of YGG: CS and useful stimulated source (655 nm) are all located in the biological window (650–1350 nm). In this work, pork tissue imaging experiments were performed by means of the hundreds of hours persistent luminescence and hundreds of times photo-stimulated property of YGG: CS. Image 1 • The persistent property of the YGG: Cr3+ was improved for more than sevenfold. • Afterglow of YGG: Cr3+, Si4+ reappear through low-energy photo-stimulation. • The efficiency photo-stimulation process can be repeated hundreds of times. • Photo-stimulation dependence YGG: Cr3+, Si4+ showed great bio-imaging property. [ABSTRACT FROM AUTHOR]

When a radiological and nuclear (R/N) emergency occurs, the categorization of individuals into those who are unaffected and those requiring medical intervention is a high priority. At times, a professional dosimeter is not available and therefore some common belongings may be used as fortuitous dosimeters. The preparation of these objects for the measurement should be such as to give the most accurate and precise results. This paper focused on the Photo-Stimulated Luminescence (PSL) response of salty crackers confronts the problem of sample preparation (mass, grain size), dose response and signal stability. The dose response was determined for doses up to 5 Gy, which allowed the calculation of the limit of detection. Additionally, the signal stability was investigated for samples irradiated with 0.3 and 3 Gy. The observed decrease of the signal does not prevent the detection in the dose range typical for R/N emergency. The main dosimetric characteristics were investigated by using two different models of PSL readers equipped with single (infrared) or double (infrared, blue light) stimulation. The results indicated that the limit of detection can be improved by applying blue light stimulation. Moreover, strong correlation of the measurements performed in the two different instruments, as well as the rapidity of the analysis and the simplicity of the operations, suggest that this method can be suitable for a rapid radiation triage of a large number of civilians in a mass casualty event. The study was simultaneously conducted by two laboratories (Ruder Bošković Institute, RBI, Croatia and Istituto Superiore di Sanità, ISS, Italy) involved in the BioPhyMeTRE project (grant No. G5684) supported by NATO Science for Peace and Security Programme., Competing Interests: The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2021 Maltar-Strmečki, Vidotto, Della Monaca, Erceg, Fattibene, Vojnić Kortmiš, Quattrini and Bortolin.)