Stimulated Luminescence Characteristics Research Articles

Optically Stimulated Luminescence (OSL) characteristics of four fluorite samples under green light stimulation

This study investigates the OSL properties of four natural fluorite color varieties (green, purple, blue-yellow banded and yellow) under green light stimulation. Thermoluminescence reveals two peaks, with the green sample showing the strongest glow. OSL exhibits a fast initial decay followed by a slower one, with phototransfer observed in purple and yellow. OSL intensity is linear with dose (1-30 Gy) for most samples, except yellow. Curve fitting using a first order kinetics model suggests multiple OSL components (between 3 and 5). Preheat treatment at 100°C increases the very fast components (thermal transfer). Anomalous fading shows rapid initial decay followed by a slower one.

Optically stimulated luminescence characteristics and dosimetric properties of copper-doped potassium sulphate

Optically stimulated luminescence characteristics and dosimetric properties of copper-doped potassium sulphate

Temperature dependence of radio- and photoluminescence and scintillation properties of Y0.6Gd2.4Al2Ga3O12:Ce,Mg single crystal

Mg2+-codoped Y0.6Gd2.4Al2Ga3O12:Ce (YGAGG:Ce,Mg) single crystal was grown by the Czochralski method and its luminescence and scintillation properties were investigated. Temperature dependence of radioluminescence (RL) yield and photoluminescence (PL) decay time was measured, and activation energy of thermal ionization process was determined from temperature-dependent PL decay time measurement. YGAGG:Ce,Mg exhibited high X-ray excited RL yield almost 5 times higher than BGO reference scintillator. Its light yield of 41,500 ph/MeV and scintillation decay times of 12 ns (2%) + 52 ns (65%) + 207 ns (33%) were measured under excitation with 662 keV γ rays from 137Cs source. Afterglow and thermally stimulated luminescence characteristics are also investigated.

Internal Radiation Levels in Natural Quartz Crystals Collected from Southwestern Nigeria; Implications on Thermoluminescence Studies

The relationship between natural thermoluminescence (TL) signal, activity concentrations and the TL sensitivities of twelve (12) quartz samples from different origins were investigated in this study. Gamma spectrometry measurements on the samples were carried out with coaxial-type Germanium detectors (Canberra Industries Inc., Meriden, CT, USA). The TL measurements on the samples were measured using a RISØ TL/OSL reader (model TL/OSL–DA–15). Concentrations of radionuclide activities were only detected in three samples with very low values as compared with world’s average. The highest dose rate in one of the samples was observed to be a factor of 15 lesser than a case of self-dose reported in the literature. The three samples with detectable activity concentrations are the one that possess highest TL signals. All the samples with an exception of one exhibit dependence of sensitization factor of 110 °C TL glow-peak on the equivalent dose (ED). This observation suggested a correlation between the ED of quartz and the sensitization factor of its 110 °C TL peak, an indication of the importance of ED in quartz TL and Optically Stimulated Luminescence (OSL) characteristics. There was no possibility of self-dose effect in all the samples and their radiation safety in exploration and applications in electronics and gemology are validated.

Effect of Li+ co-doping on the luminescence and defects creation processes in Gd3(Ga,Al)5O12:Ce scintillation crystals

Photo- and thermally stimulated luminescence characteristics, as well as photostimulated defects creation processes are investigated in the 85–510 K temperature range for the Li+ co-doped single crystal of Gd3(Ga,Al)5O12:Ce (GAGG:Ce). The results for GAGG:Ce,Li are compared with the corresponding characteristics of the GAGG:Ce and GAGG:Ce, Mg single crystals of similar host composition. The influence of Li+ and Mg2+ ions on the Ce3+ - related emission band position, temperature dependence of the photoluminescence intensity, efficiency of the Gd3+ → Ce3+ energy transfer, intensity and decay kinetics of the afterglow, and thermally stimulated luminescence characteristics is revealed. The presence of the Ce3+ → Ce4+ conversion in GAGG:Ce,Li is confirmed. The conclusion is made that, unlike GAGG:Ce,Mg, the compensation of the Li+ excess negative charge in GAGG:Ce,Li occurs due to both the Ce3+ → Ce4+ conversion and the effective formation of intrinsic crystal lattice defects. The origin of these defects as well as the origin of the electron and hole trapping centers in the GAGG:Ce,Li crystal are discussed.

Photostimulated Defect Creation Processes in the Undoped and Bi3+‐Doped Ca3Ga2Ge3O12 Garnets

The thermally stimulated luminescence characteristics of UV‐irradiated microcrystalline powders of the undoped and Bi3+‐doped Ca3Ga2Ge3O12 garnets are investigated in the 80–510 K temperature range after selective irradiation in the 4.1–5.7 eV energy range. The dependences of these characteristics on the irradiation energy, temperature, and duration, as well as on the emission energy, are obtained. The origin of the electron and hole centers of different types responsible for the observed thermally stimulated luminescence glow curve peaks is clarified, and the depths of the corresponding electron traps are determined. The electron–hole recombination processes, resulting in the appearance of the intrinsic and Bi3+‐related luminescence, are investigated. The mechanisms of the processes responsible for the photostimulated creation of various electron and hole centers under irradiation of the undoped and Bi3+‐doped Ca3Ga2Ge3O12 garnets in the band‐to‐band transition region and in the energy ranges of the intrinsic and Bi‐related absorption bands are proposed.

Effect of W and Mo co-doping on the photo- and thermally stimulated luminescence and defects creation processes in Gd3(Ga,Al)5O12:Ce crystals

Photo- and thermally stimulated luminescence characteristics of Gd3(Ga,Al)5O12:Ce single crystals co-doped with W and Mo are investigated in the 85 - 510 K temperature range and compared with the corresponding characteristics of the undoped and Ce3+ - doped Gd3(Ga,Al)5O12 single crystals of similar composition. A strong effect of the W and Mo impurity ions appears in the photoluminescence spectra and temperature dependences of the photoluminescence intensity, afterglow intensity and decay kinetics, thermally stimulated luminescence (TSL) intensity and TSL glow curves, excitation spectra of the TSL glow curve peaks and activation energy of their creation. The obtained results are explained by the enhancement of the intrinsic emission contribution into the luminescence spectrum of Gd3(Ga,Al)5O12:Ce,W and Gd3(Ga,Al)5O12:Ce,Mo due to a large concentration of various W - and Mo - related electron traps in these crystals and, consequently, the O- - type hole centers, as well as intrinsic crystal lattice defects (e.g., cation vacancies needed for the excess positive charge compensation of the W6+ and Mo6+ ions). The influence of the co-doping with W and Mo ions on the scintillation characteristics of Gd3(Ga,Al)5O12:Ce is discussed.

Thermoluminescence, photoluminescence and optically stimulated luminescence characteristics of CaSO4:Eu phosphor: Experimental and density functional theory (DFT) investigations

The CaSO4:Eu phosphor in nanocrystalline form was obtained by chemical method. The sample was annealed at various temperatures and quenched. The structural, electronic and optical properties are studied using various experimental techniques. As synthesized CaSO4:Eu particles have nanorod shapes with diameter of ~15 nm and length of ~250 nm. After annealing (at around 900 °C) a significant increase in their size (~2–4 μm) with phase transformation from hexagonal to orthorhombic was observed. Thermoluminescence (TL) and optically stimulated luminescence (OSL) intensities were found to increase with temperature up to 900 °C and decrease thereafter for 1 Gy of test dose of β-rays from 90Sr-90Yr source. However, the maximum OSL sensitivity was found to be more than that of CaSO4:Eu microcrystalline phosphor (prepared by acid recrystallization method) contrary to the usually found in the literature but much less than that of commercially available α-Al2O3:C phosphor. The activation energy for thermally assisted OSL process was found to be 0.0572 ± 0.0028 eV. The dose ranges of TL and OSL response was found from 0.04 Gy to 100 Gy and 0.02 Gy–100 Gy, respectively. The experimental results are also correlated with computational calculations based on density functional theory (DFT). The crystal structures and electronic structures of both hexagonal and orthorhombic CaSO4 and CaSO4:Eu materials show that they are direct band gap (5.67–5.86 eV) insulators, with Ca2+ substitution by Eu2+ found to introduce donor states in the band gap near Fermi level and the valence band edge of CaSO4 on doping with Eu2+ impurity ions.

Optically stimulated luminescence in enaminones

This work presents the first experimental results of optically stimulated luminescence in organic crystals type enaminones. Samples were synthesized by means of the condensation reaction of acetylacetone with four aromatics amines in acid medium. Component reactions were dissolved and heated in refluxing toluene under magnetic stirring during 14 h. Optically stimulated luminescence has been used in order to explore luminescent emission on organic solids. Optically stimulated luminescence characteristics were obtained using an automatic Lexsygsmart TL/OSL Luminescence reader. Organic crystals type enaminones exhibit good sensitivity to beta radiation. Organic crystals showed OSL response in exponential decay form. The OSL signal was increased as radiation dose was increased. Optically stimulated luminescence in organic crystals type enaminones has been reported at the first time.

Luminescence characteristics of silver and rare earth co-doped KCl single crystals grown from melt using Czochralski technique

Single crystals of KCl:Ag, KCl:Ag,Eu and KCl:Ag,Ce were grown from melt using Czochralski technique and investigated for thermally (TSL) and optically stimulated luminescence characteristics (OSL) with main focus on dosimetric applications. The XRD of crystals showed good crystalline nature with a face centered cubic KCl structure. SEM and EDAX analysis confirmed the distribution of dopants in the host lattice. Thermo luminescence (TL) emission of KCl:Ag after irradiating with 60Co gamma rays showed two TL glow peaks around 100 °C and 150 °C. An enhanced TL intensity of 3.5 times and OSL intensity of 1.5 times were observed by co-doping KCl:Ag with Ce. The result is further confirmed by taking photoluminescence and TL emission spectra of the samples. This increased TL and OSL response for KCl:Ag,Ce crystal is attributed to the formation of Vk centers formed due to the doping of Ag in KCl and the F center formed by Ce2+ on irradiation. Dose response of KCl:Ag,Ce showed linearity up to 6 Gy indicating its use in the personal dosimetry applications.

Optically stimulated luminescence characteristics of BeO nanoparticles synthesized by sol-gel method

Optically Stimulated Luminescence (OSL) properties of the sol-gel synthesized nano-powders of Beryllium Oxide (BeO) were investigated. Luminescence properties of BeO nanoparticles are dependent on the crystal structure, particle size, and morphology and therefore strongly dependent on the way of synthesis, thus the preparation was modified to enhance the OSL signal from the material. Structural, thermal and morphological properties of BeO in nanopowder and pellet forms were studied using X-Ray Diffraction (XRD), Fourier Transform Infrared Microscopy (FTIR), Simultaneous Thermal Analysis STA (Thermo Gravimetric Analysis (TGA)/Differential Scanning Calorimetry (DSC)) and Scanning Electronic Microscopy (SEM) techniques. XRD and STA analysis suggested an enhancement in crystallinity and thermal stability of the BeO with increasing sintering temperature.OSL dosimetric properties of the pellets prepared by pressing the synthesized powders were investigated in detail. Thermal stability of the signal as determined with a pulse heating experiment has shown that the OSL signal was stable up to depleted at around 300 °C, suggesting the suitability for dosimetric purposes. Dose response of OSL signals was observed to be linear in the dose range 0.1–100 Gy. The minimum detectable dose limit was estimated at around 100 μGy. Replicated measurements of the samples irradiated with the same dose indicated a good repeatability. Fading properties of the OSL signals were also studied up to 1 month. OSL signals of BeO pellets were decreased by approximately 11% at the end of 7 days and by about 17% at the end of 30 days when compared with the first readout.

Dependence of Ce3+ - related photo- and thermally stimulated luminescence characteristics on Mg2+ content in single crystals and epitaxial films of Gd3(Ga,Al)5O12:Ce,Mg

Photoluminescence and thermally stimulated luminescence of Gd3(Ga,Al)5O12:Ce single crystals and epitaxial films co-doped with different concentrations of Mg2+ ions are investigated in the 77–500 K temperature range under excitation in the 4f - 5d1 and 4f - 5d2 absorption bands of Ce3+ ions. Influence of Mg2+ ions on the photoluminescence intensity, spectrum, decay kinetics, temperature dependence of the photoluminescence intensity, and the activation energy of luminescence thermal quenching is observed. Co-doping with Mg2+ is shown to result in a drastic reduction of the afterglow and thermally stimulated luminescence and in a strong shortening of the afterglow decay kinetics. It influences also defects creation spectra and the activation energy of the photostimulated defects creation. The Mg2+ - induced changes in the characteristics of the Gd3(Ga,Al)5O12:Ce, Mg single crystals and epitaxial films are found to be strongly different, and possible reasons of these differences are discussed.

Optically and thermally stimulated luminescence characteristics of LaAlO3:Pr3+ beta irradiated

This paper reports on an investigation into the thermally stimulated luminescence (TL) and optically stimulated luminescence (OSL) characteristics of novel luminescent phosphor. A new Pr3+-doped, lanthanum aluminate (LaAlO3)-based luminescent phosphor is developed. Samples of LaAlO3:Pr3+ were irradiated to beta doses, in air, from 0.1Gy up to 50Gy and then were analyzed using both TL and continuous wavelength OSL (CW-OSL) techniques to determine their luminescent characteristics. This phosphor shows a TL glow curve, after its irradiation to beta radiation, with two TL peaks: one located around 160°C and a second at 300°C. CW-OSL response presented a fast decay into the first 20s of blue light stimulation. TL and CW-OSL response as a function of beta radiation dose were linear in the studied dose range. The high sensitivity of the CW-OSL and TL response will make this phosphor suitable for beta radiation detection. Finally, the kinetic parameters of activation energy, frequency factor and kinetic order were analyzed in the TL response using computerized glow curve deconvolution based on general order kinetic model.

Luminescent properties of scintillator nanophosphors produced by flame spray pyrolysis

In the present work flame spray pyrolysis synthesis and characterization of the nano-scale phosphors; M′-YTaO4 and M′-Y(Ta0.85Nb0.15)O4 have been studied for the first time. Phase and elemental analysis of the produced nanophosphors were carried out by X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) measurements, respectively. The surface morphology and particle size of the nanophosphors were identified using scanning electron microscopy (SEM). The XRD results reveal that the nanophosphors have monoclinic M′-YTaO4 and M′-Y(Ta0.85Nb0.15)O4 phases belonging to the presence of M´-form of fergusonite structure. The particle sizes of the nanophosphors were found to be in the range of 50–100nm. The spectroscopic characterization was performed by both radioluminescence (RL) and thermally stimulated luminescence (TSL) measurements after exposure to X-ray irradiation. Also, photoluminescence and decay times were investigated under UV excitation. The nanophosphors can be concluded as appropriate emissive materials for imaging, display and scintillator applications due to the efficient photoluminescence, moderate radioluminescence (RL) and thermally stimulated luminescence characteristics.

Effect of Mg2+ ions co-doping on luminescence and defects formation processes in Gd3(Ga,Al)5O12:Ce single crystals

Photo- and radioluminescence and thermally stimulated luminescence characteristics of Ce3+ - doped and Ce3+, Mg2+ co-doped Gd3(Ga,Al)5O12 (GAGG) single crystals of similar composition are investigated in the 9–500 K temperature range. The Ce3+ - related luminescence spectra and the photoluminescence decay kinetics in these crystals are found to be similar. Under photoexcitation in the Ce3+ - and Gd3+ - related absorption bands, no prominent rise of the photoluminescence intensity in time is observed neither in GAGG:Ce,Mg nor in GAGG:Ce crystals. The afterglow is strongly reduced in GAGG:Ce,Mg as compared to GAGG:Ce, and the afterglow decay kinetics is much faster. Co-doping with Mg2+ results in a drastic decrease of the thermally stimulated luminescence (TSL) intensity in the whole investigated temperature range and in the appearance of a new complex Mg2+ - related TSL glow curve peak around 285 K. After irradiation in the Ce3+ - related 3.6 eV absorption band, the TSL intensity in GAGG:Ce,Mg is found to be comparable with that in the GAGG:Ce epitaxial film of similar composition. The Mg2+ - induced changes in the concentration, origin and structure of the crystal lattice defects and their influence on the scintillation characteristics of GAGG:Ce,Mg are discussed.

Thermoluminescence and optically stimulated luminescence characteristics of Al2O3:C films annealed at different tempeartures

-Al2O3:C crystal is a high sensitive luminescence dosemeter, and it possesses a high thermoluminescence (TL) sensitivity, approximately 40-60 times greater than LiF: Mg, Ti. However, the crystal growth requires sophisticated laboratories, high temperatures and highly reducing atmosphere. The fluorescence and TL characteristics of -Al2O3:C ceramic are similar to those of -Al2O3:C crystal, however, it shows three TL peaks. In this work, porous alumina membranes are prepared by two-step anodization in 0.5 M/L oxalic acid at 5 ℃. We investigate the influence of annealing temperature ( 600 ℃) on thermoluminescence (TL) and optically stimulated luminescence (OSL) characteristics of Al2O3:C films and discuss the influence mechanism. The scanning electron microscopy measurement reveals that Al2O3:C film possesses highly ordered nanopores with homogeneous dimensions arranged in a closed-packed hexagonal pattern. The energy dispersive X ray spectroscopy and the Fourier transform infrared spectroscopy results indicate that oxalic acid impurity is incorporated into the porous alumina membrane in the synthesis process, after the annealing treatment, the oxalic acid impurity decomposes and C2+ replaces Al3+, which leads to the formation of F+and the C content of samples increasing with elevated annealing temperature. The X-ray diffraction measurement reveals that Al2O3:C films annealed at different temperatures are amorphous. TL measurements show that the dominated peak of Al2O3:C film is centered at around 310 ℃, owing to the number of F+increasing with the annealed temperature increasing, under the same irradiation dose, the sample annealed at 600 ℃ has the greatest TL intensity. With the increase of the irradiation dose, the TL intensity increases and the dominated peak gradually shifts to high temperature, which is consistent with the general order kinetic model. The sample annealed at 600 ℃ has the greatest TL sensitivity and its TL response shows excellent linear characteristic in as dose range of 1-10 Gy, but shows super-linear behavior in a dose range of 10-120 Gy. The OSL measurements show that with the increases of the annealed temperature and the irradiation dose, the OSL initial intensity increases and each of all samples shows a typical exponential decay. Compared with the case of -Al2O3:C crystal, the fast attenuation rate of film is dramatically accelerated. In a dose range of 1-200 Gy, the OSL responses of all samples each show an excellent linear characteristic, the sample annealed at 600 ℃ has the greatest OSL sensitivity. Compared with TL response, OSL response of Al2O3:C film shows a wider range of linear dose response. In this paper we have made a beneficial exploration for Al2O3:C films as OSL dosimerer.

Thermoluminescence and optically stimulated luminescence characteristics of Al2O3 doped with Tb

In the present work policrystals of α − Al2O3 doped with terbium were synthesized using the solvent evaporation method. The samples were prepared using Al(NO3)3·9H2O and Tb(NO3)3·5H2O reagents, with Tb concentrations between 1 and 5 mol% and thermally treated at high temperature above ∼1400 °C. X-ray diffraction measurements showed the α-phase formation of samples. TL glow curve presented an intense peak at ∼190 °C and two other with low intensity at 290 and 350 °C after gamma irradiation. The best doping concentration which presented high luminescence was the sample doped with 3 mol% of Tb. TL spectra and fluorescence measurements showed similar luminescence spectra with lines attribute to Tb3+ ions. A linear behavior to gamma dose between 1 and 20 Gy was observed in TL, using 190 °C peak as well as in OSL signal, this last carried out using 532 nm wavelength stimulation.

On the origin of cerium-related centres in lead-containing single crystalline films of Y2SiO5 : Ce and Lu2SiO5 : Ce

Absorption, electron spin resonance, and photo- and thermally stimulated luminescence characteristics are studied for single crystalline films (SCFs) of Y2SiO5 : Ce and Lu2SiO5 : Ce prepared by the liquid phase epitaxy method with the use of a PbO-containing flux. They are also compared with the characteristics of the corresponding single crystals (SCs) as well as of the undoped Y2SiO5 and Lu2SiO5 SCFs and SCs. The concentration of stable trivalent Ce3+ ions in various SCFs with different lead and cerium contents is found to be negligible. It is suggested that stable tetravalent Ce4+ ions mainly exist in the SCF due to a large concentration of Pb2+ ions whose excess volume and negative charge can be effectively compensated by relatively small tetravalent Ce4+ ions. Nevertheless, the characteristic Ce3+ emission in the SCFs of Y2SiO5 : Ce and Lu2SiO5 : Ce does appear under photoexcitation in the charge-transfer absorption region (Eexc > 4.2 eV), most probably as a result of the two-photon excitation process. Ce3+ emission is observed under excitation by the ionizing radiation as well and is explained by the recombination of free electrons from the conduction band with Ce4+ ions.

Thermoluminescence and optically stimulated luminescence characteristics of -Al2O3:C crystal powder of different particle size

In this work, we first report on the radiation dose effect of -Al2O3:C crystal powder. The thermoluminescence(TL) and optically stimulated luminescence (OSL) of the powder are investigated by RisTL/OSL-DA-15. The as-grown -Al2O3:C crystal powder of same particle size shows a single TL peak and the TL intensity increases as irradiation dose increases, but no shift of the position of the TL peak is found, which is consistent with first-order recombination kinetics. And in the same radiation dose and test conditions, with the particle size of -Al2O3:C crystal powder decreasing, the TL intensity decreases after first increase and then the TL peak is gradually increases and approaches to a stable value, which shows that the -Al2O3:C crystal powder, 4060 m in diameter, has the best TL effect. The OSL decay curve of -Al2O3:C crystal powder shows the typical exponential decay characteristics, and the relationship between OSL intensity and decay rate with the particle size of -Al2O3:C crystal powder is found to be consistent with the shallow-electronic-trap theory.

Optically Stimulated Luminescence Characteristics of Modern Flash-Flood Deposits in Small Mountain Catchments

ABSTRACT Optically Stimulated Luminescence (OSL) is increasingly being used as a reliable tool for dating fluvial deposits, with special relevance in the use for recent deposits due to the lack of alternative geochronological methods. This work presents a study on the OSL characteristics of sand sediments deposited by flash floods during the last 200 years in the Guadalentín River (Southeast Spain). Two problems can be anticipated in the luminescence properties for dating such recent flood deposits. The first problem is poor bleaching due to short duration of flood-flash flows and short transport distance along the catchment headwater. Second, a geological setting dominated by carbonate bedrock limits the amount of quartz grains suitable for age dating. This study aimed to provide a preliminary analysis of luminescence diagnostic parameters of these young samples that might show an irregular OSL behavior. These preliminary OSL tests point out that further improvements such as single grain analysis may provide more accurate De values than the performed multigrain aliquots and might be the appropriated procedure for dating these flash-flood deposits.