Measurement of scintillation decay curves by a single photon counting technique

International Nuclear Information System (INIS)

Noguchi, Tsutomu

1978-01-01

An improved apparatus suitable for the measurement of spectroscopic scintillation decay curves has been developed by combination of a single photon counting technique and a delayed coincidence method. The time resolution of the apparatus is improved up to 1.16 nsec (FWHM), which is obtained from the resolution function of the system for very weak Cherenkov light flashes. Systematic measurement of scintillation decay curves is made for liquid and crystal scintillators including PPO-toluene, PBD-xylene, PPO-POPOP-toluene, anthracene and stilbene. (auth.)

Synthesization of the Ar VIII 3s-3p beam-foil decay curve

International Nuclear Information System (INIS)

Lindgaard, A.; Veje, E.

1981-01-01

The beam-foil decay curve for the 3s-3p transition in Ar VIII has been simulated from experimentally determined relative initial level populations and transition probabilities calculated in the numerical Coulomb approximation. Good agreement is observed between simulated and measured decay curves. A discussion of the simulation is given. (Auth.)

Determination of the kinetic parameters of Be O using isothermal decay method

Energy Technology Data Exchange (ETDEWEB)

Azorin N, J.; Torijano C, E. [Universidad Autonoma Metropolitana, Unidad Iztapalapa, Av. San Rafael Atlixco 186, Col. Vicentina, 09340 Mexico D. F. (Mexico); Azorin V, C.; Rivera M, T., E-mail: azorin@xanum.uam.mx [IPN, Centro de Investigacion en Ciencia Aplicada y Tecnologia Avanzada, Av. Legaria 694, Col. Irrigacion, 11500 Mexico D. F. (Mexico)

2015-10-15

Full text: Most of the existing methods for obtaining the frequency factors make use of the trap depth (activation energy) making some assumptions about the order of the kinetics. This causes inconsistencies in the reported values of trapping parameters due that the values of the activation energy obtained by different methods differ appreciably among them. Then, it is necessary to use a method independent of the trap depth making use of the isothermal luminescence decay method. The trapping parameters associated with the prominent glow peak of Be O (280 degrees C) are reported using isothermal luminescence decay method. As a check, the trap parameters are also calculated by glow curve shape (Chen s) method after isolating the prominent glow peak by thermal cleaning technique. Our results show a very good agreement between the trapping parameters calculated by the two methods. Isothermal luminescence decay method was used for determining the trapping parameters of Be O. Results obtained applying this method are in good agreement with those obtained using other methods, except in the value of the frequency factor. (Author)

Discrete breathers and the anomalous decay of luminescence

International Nuclear Information System (INIS)

Mihokova, E; Schulman, L S

2010-01-01

Some years ago an anomaly was noted in the decay of luminescence in certain doped alkali halides. The anomaly was eventually explained using a factor 1 billion (10 9 ) slowdown in lattice relaxation, a remarkable stretching of time scales. This slowdown was found to be caused by the creation of a 'breather' in the neighborhood of the dopant. Discrete breathers are nondispersive classical excitations that are known to be significant in many natural systems. Broad ranging reviews of mathematical techniques and physical applications have recently appeared. In the present review we focus on the occurrence of breathers in doped alkali halides. Several more general properties of breathers have arisen from this study and these are presented as well. Among them is the study of the quantum breather, its quantization and stability, a topic less fully explored than the classical theory because it does not yield easily to numerical simulation. (topical review)

Uranyl(VI) luminescence spectroscopy at elevated temperatures

Energy Technology Data Exchange (ETDEWEB)

Steudtner, Robin; Franzen, Carola; Brendler, Vinzenz [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Div. Surface Processes; Haubitz, Toni [Brandenburg Univ. of Technology, Cottbus-Senftenberg (Germany)

2016-07-01

We studied the influence of temperature and ionic strength on the luminescence characteristics (band position, decay time and intensity) of the free uranyl ion (UO{sub 2}{sup 2+}) in acidic aqueous solution. Under the chosen conditions an increasing temperature reduced both intensity and luminescence decay time of the UO{sub 2}{sup 2+} luminescence, but the individual U(VI) emission bands did not change.

Computerised curve deconvolution of TL/OSL curves using a popular spreadsheet program.

Science.gov (United States)

Afouxenidis, D; Polymeris, G S; Tsirliganis, N C; Kitis, G

2012-05-01

This paper exploits the possibility of using commercial software for thermoluminescence and optically stimulated luminescence curve deconvolution analysis. The widely used software package Microsoft Excel, with the Solver utility has been used to perform deconvolution analysis to both experimental and reference glow curves resulted from the GLOw Curve ANalysis INtercomparison project. The simple interface of this programme combined with the powerful Solver utility, allows the analysis of complex stimulated luminescence curves into their components and the evaluation of the associated luminescence parameters.

Computerised curve deconvolution of TL/OSL curves using a popular spreadsheet program

International Nuclear Information System (INIS)

Afouxenidis, D.; Polymeris, G. S.; Tsirliganis, N. C.; Kitis, G.

2012-01-01

This paper exploits the possibility of using commercial software for thermoluminescence and optically stimulated luminescence curve deconvolution analysis. The widely used software package Microsoft Excel, with the Solver utility has been used to perform deconvolution analysis to both experimental and reference glow curves resulted from the Glow Curve Analysis Intercomparison project. The simple interface of this programme combined with the powerful Solver utility, allows the analysis of complex stimulated luminescence curves into their components and the evaluation of the associated luminescence parameters. (authors)

Luminescence enhancement in irradiated polyethylene

International Nuclear Information System (INIS)

Charlesby, A.; Owen, G.P.

1976-01-01

Results are presented for the luminescence decay in polyethylene following irradiation at liquid nitrogen temperature and its enhancement on application of an electric field. It is found that both the luminescence enhancement and its subsequent decay may be described by a model involving electron tunnelling from a monoenergetic trap distribution to the parent positive ion. The possible nature of the trap is briefly discussed. (author)

Investigation on luminescence enhancement and decay characteristics of long afterglow nanophosphors for dark-vision display applications

Energy Technology Data Exchange (ETDEWEB)

Swati, G.; Chawla, S.; Mishra, S.; Rajesh, B.; Vijayan, N.; Sivaiah, B.; Dhar, A.; Haranath, D., E-mail: haranath@nplindia.org

2015-04-01

Graphical abstract: - Highlights: • Synthesis and structural characterization has been performed on long afterglow SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+} nanophosphor having afterglow time of ∼12 h. • Studied the effect of various fuels used for synthesis of nanophosphors on the decay and luminescence characteristics. Interestingly, afterglow times varied significantly with different fuels used for the synthesis of the nanophosphor. • Excitation by different illuminants has profound influence on the luminescence intensity and afterglow times of the synthesized nanophosphor. • Such studies could be guidelines for appropriate usage of nanophosphor under different lighting environment. - Abstract: Long afterglow SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+} nanophosphors were synthesized via a facile but effectual auto-combustion technique followed by post-annealing treatment at elevated temperatures. The influence of various fuels during synthesis and thereafter improvement in the luminescence decay characteristics under various illuminant irradiations of long afterglow nanophosphors have been reported. Extensive studies on structural, morphological and luminescent properties of the as-synthesized afterglow nanophosphors have been presented. Powder X-ray diffraction studies confirm the presence of high-purity, single-phase monoclinic nanophosphors. HRTEM investigations confirm the formation of nanophosphors of particle size less than 50 nm. Photoluminescence emission is attributed to the characteristic d–f transition (4f{sup 6}5d{sup 1}→4f{sup 7}) of Eu{sup 2+} ions and was positioned at 512 nm. As-synthesized nanophosphors exhibit considerable confinement effects resulting into blue shift in emission maxima as compared to their bulk counterparts. The mechanism underlined for long afterglow has been discussed using trapping–detrapping model. The nanophosphor being multifunctional finds many interesting applications including dark-vision display

Luminescence properties of LiPrxCe1-xP4O12

International Nuclear Information System (INIS)

Shalapska, T.; Stryganyuka, G.; Trotsc, D.; Demkiv, T.; Gektin, A.; Voloshinovskii, A.; Dorenbos, P.

2010-01-01

LiPr 1-x Ce x P 4 O 12 (x=0, 0.002, 0.02; 0.1) powder samples were prepared using the melt solution technique. Luminescent parameters of LiPr 1-x Ce x P 4 O 12 phosphors have been investigated under ultraviolet-vacuum ultraviolet (3-12 eV) synchrotron radiation and X-rays excitation at room and near liquid He temperatures. Excitation luminescence spectra of Ce 3+ emission, luminescent spectra and decay curves from the lower excited state levels of the 4f 1 5d 1 and 5d 1 electronic configuration of the Pr 3+ and Ce 3+ , respectively, clearly indicate energy transfer from Pr 3+ to Ce 3+ . Energy migration proceeds via the Pr-sublattice followed by nonradiation transfer from Pr 3+ to Ce 3+ ions.

Improved scintillation luminescence and thermal stability of In{sub 2}Si{sub 2}O{sub 7} ceramic phosphor

Energy Technology Data Exchange (ETDEWEB)

Xu, Jian; Cao, Lei; Feng, Yongyi [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Huang, Yanlin, E-mail: hang@suda.edu.cn [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Wang, Yaorong [State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123 (China); Qin, Lin [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of); Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2017-03-15

In{sub 2}Si{sub 2}O{sub 7} is a known indium-based scintillator with fast ultraviolet photoluminescence. Unfortunately the emission only can be detected below 200 K. the poor thermal stability limits its application at room temperature. In this work, the luminescence improvement of In{sub 2}Si{sub 2}O{sub 7} was realized by F{sup −}-ions doping in the lattices. The ceramic phosphors were via typical solid-state reaction method. The pure crystalline phase with thortveirite-type structure was confirmed by X-ray diffraction (XRD) Rietveld refinements. The photoluminescence (PL) emission and excitation spectra together with the luminescence thermal stability were tested. The fluorescence decay curves CIE emission Stokes shifts were measured. The ceramic samples could present blue luminescence with maximum wavelength at about 340 nm under the excitation of UV light or high energy X-ray irradiation. The pure sample only presents luminescence below 200 K, however, the F-doping can be greatly enhance the luminescence thermal stability. The F-doped In{sub 2}Si{sub 2}O{sub 7} could present emission signals with fast decay lifetime of 850 ns at room temperature. The luminescence transitions from the In{sup 3+}-O{sup 2−} charge transfer (CT) were discussed on the structure properties.

The characteristics of rapid detection of irradiated foods by photostimulated luminescence (PSL)

International Nuclear Information System (INIS)

Sekiguchi, Masayuki; Yamazaki, Masao; Mizuno, Hiroaki; Goto, Michiko; Hagiwara, Shoji; Todoriki, Setsuko; Honda, Katsunori

2007-01-01

The Photostimulated luminescence (PSL) method offered a rapid, convenient and sensitive way for detecting irradiated food. We developed a new PSL system with the tree classification modes for identifying irradiated foods. The present study reports the changes of the signal intensities and the typical decay curves of PSL for irradiated the powdered leaf products and several kinds of silicate minerals under dark storage. Any of powdered leaf products under dark storage at 4-50degC showed the typical decay curves of PSL even after 5 months, and irradiated paprika and yellow ocher could be still identify after heat-treatment at 120degC. PSL intensities of silicate minerals increased with the increase of radiation dose and show a linear relationship up to a about 1 kGy, but varied among silicate minerals. (author)

Decay kinetics and thermally stimulated luminescence of Mn.sup.4 +./sup. in SrTiO.sub.3./sub

Czech Academy of Sciences Publication Activity Database

Bryknar, Z.; Potůček, Zdeněk; Trepakov, Vladimír; Shen, M. Y.; Goto, T.

2001-01-01

Roč. 154, - (2001), s. 341-345 ISSN 1042-0150 R&D Projects: GA ČR GA202/00/1425 Institutional research plan: CEZ:AV0Z1010914 Keywords : thermally stimulated luminescence * decay kinetics * strontium titanate * manganese Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.380, year: 2001

Effect of retrapping on the persistent luminescence in strontium silicate orange–yellow phosphor

International Nuclear Information System (INIS)

Xu, Xuhui; Yu, Xue; Zhou, Dacheng; Qiu, Jianbei

2013-01-01

The orange–yellow long persistent luminescence in Sr 3 SiO 5 :Eu 2+ , Er 3+ with the chromaticity coordination of (0.48, 0.49) can persist for over 20 h above the recognizable intensity level (≥0.32 mcd/m 2 ) because of retrapping carriers by the deep traps. The incorporation of Er 3+ into Sr 3 SiO 5 :Eu 2+ generates a large number of shallow traps responsible for the fast decay component as well as deep traps responsible for the decay tail of the LPL. It demonstrates that the retrapping of the carrier released from a trap plays an important role in the persistent luminescence process. - Graphical abstract: LPL decay curves of Sr 3−x−y SiO 5 :xEu 2+ , yEr 3+ (x=0.0025, y=0, 0.0025). Inset: Orange–yellow emission images recorded using a classic Reflex digital camera with exposure times varying with the persistent luminescence times. Display Omitted - Highlights: • The persistence time of Sr 3 SiO 5 :Eu 2+ , Er 3+ lasts over 20 h above the recognizable intensity level. • The incorporation of Er 3+ into Sr 3 SiO 5 :Eu 2+ generates a large number of shallow traps. • The experimental results provide an evidence for the retrapping process in LPL processes

Aspects of pre-dose and other luminescence phenomena in quartz absorbed dose estimation

International Nuclear Information System (INIS)

Adamiec, G.

2000-01-01

The understanding of all luminescence processes occurring in quartz is of paramount importance in the further development of robust absorbed dose estimation techniques (for the purpose of dating and retrospective dosimetry). The findings presented in this thesis, aid future improvements of absorbed dose estimation techniques using quartz by presenting investigations in the following areas: 1) interpretation of measurement results, 2) numerical modelling of luminescence in quartz, 3) phenomena needing inclusion in future physical models of luminescence. In the first part, the variability of properties of single quartz grains is examined. Through empirical and theoretical considerations, investigations are made of various problems of measurements of luminescence using multi-grain aliquots, and specifically areas where the heterogeneity of the sample at the inter-grain level may be misinterpreted at the multi-grain-aliquot level. The results obtained suggest that the heterogeneity of samples is often overlooked, and that such differences can have a profound influence on the interpretation of measurement results. Discussed are the shape of TL glow curves, OSL decay curves, dose response curves (including consequences for using certain signals as proxies for others), normalisation procedures and D E estimation techniques. Further, a numerical model of luminescence is proposed, which includes multiple R-centres and is used to describe the pre-dose sensitisation in quartz. The numerical model exhibits a broad-scale behaviour observed experimentally in a sample of annealed quartz. The shapes of TAC for lower (20 Gy) and higher doses (1 kGy) and the evolution with temperature of the isothermal sensitisation curves are qualitatively matched for the empirical and numerical systems. In the third area, a preliminary investigation of the properties of the '110 deg. C peak' in the 550 nm emission band, in annealed quartz is presented. These properties are in sharp contrast with

Novel lanthanide doped micro- and mesoporous solids. Characterization of ion-host-interactions, species distribution and luminescence properties using time-resolved luminescence spectroscopy

International Nuclear Information System (INIS)

Gessner, Andre

2010-12-01

In this work lanthanide-doped microporous zeolites, microporous-mesoporous hybrid materials and mesoporous silicates were investigated regarding their luminescence properties and the ion-host-interactions using time-resolved luminescence spectroscopy. Thereby, time-resolved emission spectra (TRES) provide information in the wavelength and time domain. For the analysis of the TRES a broad set of analytic methods was applied and thus a corresponding ''toolbox'' developed. Fitting of the luminescence decays was performed with a discrete number of exponentials and supported by luminescence decay times distributions. Time-resolved area normalized emission spectra (TRANES), an advancement of TRES, could be used for the determination of the number of emissive lanthanide species in porous materials for the first time. Calculation of the decay-associated spectra (DAS) allowed the correlation of spectral information with luminescence decay times and thus delivered the luminescence spectra of the different europium species. For europium(III) we could use in addition the time-dependent asymmetry ratio and spectral evolution of the 5 D 0 - 7 F 0 -transition with time to obtain further information about the distribution of the lanthanide ions in the host material. Luminescence decay times and spectra allowed conclusions on the number of OH-oscillators in and the symmetry of the first coordination sphere. For the microporous and microporous-mesoporous materials were found different lanthanide species, which were characterized by the above mentioned methods. These lanthanide species can be found on different positions in the host material. One position is located deep in the pore system. Here, lanthanide ions are hardly accessible for water and mainly coordinated by framework oxygens. This results in long luminescence decay times and distorted coordination spheres. The second position can be found near or on the outer surface or in the mesopores. Lanthanide ions located here, are

Experimental and simulated beam-foil decay curves for some transitions in Zn II

International Nuclear Information System (INIS)

Hultberg, S.; Liljeby, L.; Mannervik, S.; Veje, E.; Lindgaard, A.

1980-01-01

Experimental beam-foil decay curves for the 4s-4p, 4p-4d, 4d-4f, and the 4p-5s transitions in Zn II are compared to decay curves synthesized from transition probabilities calculated in the numerical Coulomb approximation and either measured initial level populations or population models. Good agreement exists between experimental curves and those based on the measured initial level populations for the 5s, 4d, and 4f levels while certain deviations are noted for the 4p term. None of the applied population models reproduce all experimental curves satisfyingly well. In addition, lifetimes are determined experimentally for 7 terms in Zn II, and good agreement with the numerical Coulomb approximation lifetimes is generally found except for some p terms. Beam-foil excitation-mechanism results for zinc are presented and compared to previous results from light projectiles. (Auth.)

The dependence of orange-red IRSL decay curves of potassium feldspars on sample temperature

International Nuclear Information System (INIS)

Fattahi, Morteza

2004-01-01

This paper presents the effects of stimulation temperature on the infrared stimulated orange-red (600-650 nm) luminescence emission (orange-red infrared simulated luminescence (IRSL)) in potassium feldspar. Investigations explore the relationship between initial (0-2 s), integral (0-100 s), net initial (0-2 s less background over 2 s), net integral (0-100 s less background over 100 s) and last 2 s of the orange-red IRSL signals obtained for 100 s versus stimulation temperature (20-460 degree sign C) on both unpreheated and preheated samples. In the potassium feldspar sample examined, competition effects, including thermal enhancement, depletion and possibly quenching affect the orange-red IRSL signals measured. Observed effects (e.g., thermal enhancement, thermal activation energy and the decay rate) over the temperature range 20-120 degree sign C may be explained by tunnelling luminescence processes, IR transitions to the conduction band following excitations from ground state of electron trap by acquiring thermal energy from the lattice and or the random-walk band-tail model. Preheating prior to orange-red IRSL and Thermoluminescence (TL) measurements provides evidence that there are both shallow and deep traps responsible for low- and high-temperature orange-red IRSL and TL peaks. The effects of both preheating and IR bleaching on the orange-red thermally stimulated luminescence (red emission during thermoluminescence, RTL) provide evidence that bleached RTL traps have no significant contribution in the production of orange-red IRSL signals

Solute concentration dependence of the decay curves of the liquid scintillation

International Nuclear Information System (INIS)

Onishi, Masayoshi; Niki, Eiji.

1976-01-01

The decay curves of the liquid scintillation of 2,5-diphenyloxazole (PPO) in toluene by the irradiation of β ray from 14 C were measured. Solute concentration dependences of the decay times of the fast and slow components were studied. The decay time tau sub(f) of the fast component of the air saturated scintillator was the smallest at 1.8x10 -2 --4.5x10 -2 mol/l, and about (3.4--3.5)ns. When the concentration became less than 1.8x10 -2 mol/l, the peak of the decay curve became roundish and the pulse width became large. The increase of the necessary time for the energy transfer due to the difficulty of the nonradiative transfer from excited solvent molecules to the solute was the reason. When the concentration became less than about 2.26x10 -3 mol/l, tau sub(f) became larger and the energy transfer became radiative. The pulse width and tau sub(f) were very small because of oxygen quenching compared with oxygen free. At higher concentrations such as 1.6x10 -1 and 2.3x10 -1 mol/l, the effect of the PPO excimer was observed on the fast component, and tau sub(f) became larger apparently. This denied the presumption of the close relation between PPO molecular interaction and the slow component together with the fact that the decay time tau sub(s) of the slow component was independent of PPO concentration. (auth.)

Effect of retrapping on the persistent luminescence in strontium silicate orange–yellow phosphor

Energy Technology Data Exchange (ETDEWEB)

Xu, Xuhui; Yu, Xue, E-mail: yuyu6593@126.com; Zhou, Dacheng; Qiu, Jianbei, E-mail: qiu@kmust.edu.cn

2013-10-15

The orange–yellow long persistent luminescence in Sr{sub 3}SiO{sub 5}:Eu{sup 2+}, Er{sup 3+} with the chromaticity coordination of (0.48, 0.49) can persist for over 20 h above the recognizable intensity level (≥0.32 mcd/m{sup 2}) because of retrapping carriers by the deep traps. The incorporation of Er{sup 3+} into Sr{sub 3}SiO{sub 5}:Eu{sup 2+} generates a large number of shallow traps responsible for the fast decay component as well as deep traps responsible for the decay tail of the LPL. It demonstrates that the retrapping of the carrier released from a trap plays an important role in the persistent luminescence process. - Graphical abstract: LPL decay curves of Sr{sub 3−x−y}SiO{sub 5}:xEu{sup 2+}, yEr{sup 3+} (x=0.0025, y=0, 0.0025). Inset: Orange–yellow emission images recorded using a classic Reflex digital camera with exposure times varying with the persistent luminescence times. Display Omitted - Highlights: • The persistence time of Sr{sub 3}SiO{sub 5}:Eu{sup 2+}, Er{sup 3+} lasts over 20 h above the recognizable intensity level. • The incorporation of Er{sup 3+} into Sr{sub 3}SiO{sub 5}:Eu{sup 2+} generates a large number of shallow traps. • The experimental results provide an evidence for the retrapping process in LPL processes.

Decay pathway and high-temperature luminescence of Eu{sup 3+} in Ca{sub 2}Gd{sub 8}Si{sub 6}O{sub 26}

Energy Technology Data Exchange (ETDEWEB)

Chambers, M.D. [Engineering Materials Department, College of Engineering, University of California, Santa Barbara, CA 93106-5050 (United States)], E-mail: chambers@engineering.ucsb.edu; Rousseve, P.A.; Clarke, D.R. [Engineering Materials Department, College of Engineering, University of California, Santa Barbara, CA 93106-5050 (United States)

2009-03-15

The temperature-dependent luminescence of Eu:Ca{sub 2}Gd{sub 8}Si{sub 6}O{sub 26} and its decay pathways are investigated in order to assess the utility of the material as a thermometric phosphor. Non-radiative decays are found to compete with radiative processes even at room temperature. A decay pathway involving decay through charge-transfer states is proposed based on the decay profiles of emissions from {sup 5}D{sub 1} and {sup 5}D{sub 0} levels and on the temperature sensitivity of the spectra as observed after excitation by several wavelengths. The implications of this on solid-state lighting are also discussed.

Luminescence spectroscopy of Rb2KTiOF5 oxyfluoride single crystals

Science.gov (United States)

Kozlov, A. V.; Pustovarov, V. A.; Sarychev, M. N.; Isaenko, L. I.

2017-09-01

Spectra of photoluminescence (PL) and X-ray excited luminescence (XRL) in region of 1.5-5.5 eV, PL excitation spectra using synchrotron radiation (3.7-22 eV), time-resolved impulse cathode-luminescence (ICL) spectra, the temperature depending of the XRL, decay kinetics as well as thermoluminescence curves were measured for single crystals Rb2KTiOF5, a promising nonlinear optical material. Single crystals are transparent in microwave, visible and near UV range, inter-band transition energy is Eg = 4.2 eV. Crystalline structure has two disordered mixed position O/F, phase transition in the region of 215 K. All the obtained results indicate that in luminescence spectra nonelementary band 2.2 eV is connected to the emission of self-trapped excitons. Nonelementary band 2.2 eV associated with the presence local distortion in the octahedron TiOF5. It is observed that at interband excitation in VUV region at energies more than 3.5 Eg the effect of multiplication of electronic excitations appears. That determines the high output of XRL and ICL. Luminescence methods of quality control of grown crystals are proposed.

A non-iterative method for fitting decay curves with background

International Nuclear Information System (INIS)

Mukoyama, T.

1982-01-01

A non-iterative method for fitting a decay curve with background is presented. The sum of an exponential function and a constant term is linearized by the use of the difference equation and parameters are determined by the standard linear least-squares fitting. The validity of the present method has been tested against pseudo-experimental data. (orig.)

Exponential Decay Nonlinear Regression Analysis of Patient Survival Curves: Preliminary Assessment in Non-Small Cell Lung Cancer

Science.gov (United States)

Stewart, David J.; Behrens, Carmen; Roth, Jack; Wistuba, Ignacio I.

2010-01-01

Background For processes that follow first order kinetics, exponential decay nonlinear regression analysis (EDNRA) may delineate curve characteristics and suggest processes affecting curve shape. We conducted a preliminary feasibility assessment of EDNRA of patient survival curves. Methods EDNRA was performed on Kaplan-Meier overall survival (OS) and time-to-relapse (TTR) curves for 323 patients with resected NSCLC and on OS and progression-free survival (PFS) curves from selected publications. Results and Conclusions In our resected patients, TTR curves were triphasic with a “cured” fraction of 60.7% (half-life [t1/2] >100,000 months), a rapidly-relapsing group (7.4%, t1/2=5.9 months) and a slowly-relapsing group (31.9%, t1/2=23.6 months). OS was uniphasic (t1/2=74.3 months), suggesting an impact of co-morbidities; hence, tumor molecular characteristics would more likely predict TTR than OS. Of 172 published curves analyzed, 72 (42%) were uniphasic, 92 (53%) were biphasic, 8 (5%) were triphasic. With first-line chemotherapy in advanced NSCLC, 87.5% of curves from 2-3 drug regimens were uniphasic vs only 20% of those with best supportive care or 1 drug (p<0.001). 54% of curves from 2-3 drug regimens had convex rapid-decay phases vs 0% with fewer agents (p<0.001). Curve convexities suggest that discontinuing chemotherapy after 3-6 cycles “synchronizes” patient progression and death. With postoperative adjuvant chemotherapy, the PFS rapid-decay phase accounted for a smaller proportion of the population than in controls (p=0.02) with no significant difference in rapid-decay t1/2, suggesting adjuvant chemotherapy may move a subpopulation of patients with sensitive tumors from the relapsing group to the cured group, with minimal impact on time to relapse for a larger group of patients with resistant tumors. In untreated patients, the proportion of patients in the rapid-decay phase increased (p=0.04) while rapid-decay t1/2 decreased (p=0.0004) with increasing

Modeling of the shape of infrared stimulated luminescence signals in feldspars

DEFF Research Database (Denmark)

Pagonis, Vasilis; Jain, Mayank; Murray, Andrew S.

2012-01-01

This paper presents a new empirical model describing infrared (IR) stimulation phenomena in feldspars. In the model electrons from the ground state of an electron trap are raised by infrared optical stimulation to the excited state, and subsequently recombine with a nearest-neighbor hole via...... corresponds to a fast rate of recombination processes taking place along the infrared stimulated luminescence (IRSL) curves. The subsequent decay of the simulated IRSL signal is characterized by a much slower recombination rate, which can be described by a power-law type of equation.Several simulations...

Luminescent emission of LiF: Mg, Ti exposed to UV radiation

International Nuclear Information System (INIS)

Estrada G, A.; Castano M, V.M.; Cruz Z, E.; Garcia F, F.

2002-01-01

It was investigated the luminescent emission stimulated by heat (Tl) of LiF: Mg, Ti crystals which were exposed to UV radiation coming from a mercury lamp. Since this crystal depends on the thermal history, it has been used a thermal treatment consisting of a baking at 380 C during one hour for each reading and they were irradiated with UV. The brilliance curves between 5 and 840 minutes of exposure in the face of UV light were obtained. An important loss in the response, starting from 150 minutes of irradiation was observed. Also the relative intensity of the brilliance curve decay when the crystals being stored in darkness and room temperature conditions, which is according to the results in the literature about. (Author)

Luminescence properties of Ce3+ doped gadolinium-calcium-silicaborate glass scintillator

International Nuclear Information System (INIS)

Park, J.M.; Ha, D.H.; Kaewjeang, S.; Maghanemi, U.; Kothan, S.; Kaewkhao, J.; Kim, H.J.

2016-01-01

In this work, the Ce 3+ doped gadolinium-calcium-silicaborate glass scintillators of the composition ratio 25Gd 2 O 3 :10CaO:10SiO 2 :(55−x)B 2 O 3 :xCeF 3 , have been fabricated by using the melt-quenching technique. The doping concentration of the Ce 3+ was varied from 0.05 mol% to 2.5 mol%. The 4f-5d transition of the Ce 3+ allowed scintillation with a fast decay time. The absorption spectrum, X-ray induced emission spectrum, photo luminescence spectrum, laser luminescence spectrum and decay time of the scintillators were measured for studying the luminescence properties. From the X-ray induced emission spectrum result, we checked the trend between doping concentration and light yield. The laser induced luminescence spectrum was measured while changing the temperature from 300 K to 10 K. We also measured the decay time by using the laser excitation of the 0.15 mol% Ce 3+ doped glass scintillator. - Highlights: • Ce 3+ doped gadolinium-calcium-silicaborate glass scintillators were developed. • Glass is easily fabricated with large sizes and various doping materials. • The luminescence properties are studied by using various radiation sources. • The light yield and decay time were measured at low temperature. • One decay time component is found.

Luminescence decay of S Zn::Ag and O Zn:Ga scintillation detectors excited by a pulsed laser; Evolucion temporal de la luminiscencia producida por un laser pulsado de los detectores de centello SZn:Ag y OZn:Ga

Energy Technology Data Exchange (ETDEWEB)

Romero, L.; Campos, J.

1981-07-01

In the present work a high sensitivity experimental set up for luminescence decay measurements in the 1 0 {sup -}1 sec range has been developed. As an application, luminescence light decay In S Zn:Ag and 0Zn:Ga after excitation by a pulsed N{sub 2} laser has been measured. In SZnrAg, measurements of total light decay was compared with donor acceptor pairs theory. In both substances, spectral evolution in the first 15 sec was investigated. (Author) 4 refs.

Luminescence studies on Dy3+ doped calcium boro-tellurite glasses for White light applications

Science.gov (United States)

Karthikeyan, P.; Vijayakumar, R.; Marimuthu, K.

2017-09-01

A new series of Dy3+ doped calcium boro-tellurite glasses have been prepared by melt quenching technique and their spectroscopic properties were studied through FTIR, absorption luminescence and lifetime spectral measurements. FTIR studies have been made to explore the presence of various stretching and bending vibrations of different borate and tellurite groups in the prepared glasses. The bonding parameter values were estimated from the absorption band positions using Nephelauxetic ratios to examine the nature of the metal-ligand bond. The optical band gap and Urbach energy (ΔE) values were obtained from the absorption spectra to explore the electronic band structure of the studied glasses. Judd-Ofelt (JO) theory have been used to determine the JO intensity parameters (Ω2, Ω4, Ω6) following the least square fitting procedure between the experimental and calculated oscillator strength values. The luminescence spectra of the Dy3+ doped calcium boro-tellurite glasses exhibit two intense emission bands corresponding to the 4F9/2→6H15/2 and 4F9/2→6H13/2 transitions. Further, they exhibit less intense emission band due to the 4F9/2→6H11/2 transition. Luminescence spectra were characterized through CIE 1931 chromaticity diagram to obtain the dominant emission color of the prepared glasses. The JO intensity parameters and refractive index values have been used to calculate the radiative parameters such as transition probabilities (AR), branching ratios (βR) and stimulated emission cross-section (σPE) values for the observed transitions in the luminescence spectra. The decay curves of all the studied glasses found to exhibit non-exponential behavior and further to understand the energy transfer process takes place between the Dy3+ ions, the decay curves were fitted to the Inokuti-Hirayama (IH) model. The structural and optical properties of the Dy3+ doped calcium boro-tellurite glasses have been studied as a function of different metal cations (Zn, Cd, Pb and

Metal plasmon enhanced europium complex luminescence

International Nuclear Information System (INIS)

Liu Feng; Aldea, Gabriela; Nunzi, Jean-Michel

2010-01-01

The plasmon enhanced luminescence of a rare-earth complex Tris(6, 6, 7, 7, 8, 8, 8-heptafluoro-2, 2-dimethyl-3, 5-octanedionato) europium (Eu(fod) 3 ) was investigated. A polyvinyl alcohol (PVA) thin film was successfully adopted as a spacer to separate the Eu complex from the silver island film (SIF), and five-fold enhancement of the radiative decay rate of the Eu complex on SIF was demonstrated based on the luminescence intensity and lifetime measurement. Investigation of the distance dependent luminescence indicates that 7 nm is an optimal distance for SIF enhanced Eu luminescence. Plasmon enhanced rare-earth luminescence based on an organic film spacer would find potential applications in plasmon enhanced organic light emitting diode (OLED) devices.

Luminescence properties of Eu{sup 2+} in silver decacalcium heptakis-orthophosphate AgCa{sub 10}(PO{sub 4}){sub 7}

Energy Technology Data Exchange (ETDEWEB)

Zhang, Hongzhi [School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Zhang, Xinmin, E-mail: zhangxm@csuft.edu.cn [School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Wu, Luyi; Zheng, Wei; Jiang, Wei [School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); He, Mengdong [Institute of Mathematics and Physics, Central South University of Forestry and Technology, Changsha 410004 (China); Yuan, Guangming [School of Materials Science and Engineering, Central South University of Forestry and Technology, Changsha 410004 (China); Seo, Hyo Jin [Department of Physics and Interdisciplinary Program of Biomedical, Mechanical & Electrical Engineering, Pukyong National University, Busan 608-737 (Korea, Republic of)

2017-05-15

The luminescence properties of Eu{sup 2+} in AgCa{sub 10}(PO{sub 4}){sub 7} has been studied at room and low temperature and the decay times of Eu{sup 2+} in this matrix have been measured and analyzed. According to the crystal structure of AgCa{sub 10}(PO{sub 4}){sub 7}, photoluminescence (PL) spectra and decay curves, the substitution of Eu{sup 2+} ions is possible to four different Ca{sup 2+} sites. The red-shift of emission wavelength and energy transfer process between Eu{sup 2+} activator ions are discussed.

Luminescence properties of Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor

Energy Technology Data Exchange (ETDEWEB)

Lei Bingfu, E-mail: tleibf@jnu.edu.cn [Department of Physics, Jinan University, Guangzhou 510632 (China); Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Man Shiqing [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Department of Electronic Engineering, Jinan University, Guangzhou 510632 (China); Liu Yingliang [Department of Chemistry and Nanochemistry Institute, Jinan University, Guangzhou 510632 (China); Yue Song [Department of Physics, Jinan University, Guangzhou 510632 (China)

2010-12-01

We report on a luminescent phenomenon in Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} afterglow phosphor. XRD, photoluminescence, afterglow emission spectra and long-lasting phosphorescence decay curve are used to characterize this phosphor. After irradiation by a 267-nm UV light for 5 min, the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor emits intense reddish-orange emitting afterglow from the {sup 4}G{sub 5/2} to {sup 6}H{sub J} (J = 5/2, 7/2, 9/2) transitions, and its afterglow can be seen with the naked eye in the dark clearly for more than 1 h after removal of the excitation source. Photoluminescence spectra reveal that the reddish-orange light-emitting long-lasting phosphorescence originate from the mixture of Sm{sup 3+} characteristic transitions. The afterglow decay curve of the Sm{sup 3+}-doped Sr{sub 3}Sn{sub 2}O{sub 7} phosphor contains a fast decay component and another slow decay one. The possible mechanism of this reddish-orange light-emitting LLP phosphor is also discussed based on the experiment results.

Synthesis and luminescent properties of a novel green-emitting Tb (Ⅲ) complex based on amino-modified fluorine silicone oil and isophorone diisocyanate

Science.gov (United States)

Hao, Haixia; Chu, Yang; Yu, Zhenjiang; Xie, Hongde; Seo, Hyo Jin

2017-10-01

The novel luminescent polymer-rare earth complexes, denoted as (PFSi-IPDI)-Tb(Ⅲ)-Phen, have been successfully synthesized and can be made into flexible films. Amino-modified fluorine silicone oil-isophorone diisocyanate (PFSi-IPDI) was used as the host macromolecular ligand, and 1, 10-Phenanthroline (Phen) as the secondary small-molecular co-ligand. The luminescent lanthanide complexes were characterized by fourier transform infrared (FITR), scanning electron microscope (SEM), thermogravimetric analysis (TGA). The luminescent properties were investigated through photoluminescence excitation (PLE) and emission (PL) spectroscopy. FTIR analysis verifies the successful preparation and integration of PFSi-IPDI to Tb3+. The comparatively uniform morphological structure can be observed in the images of SEM. The polymer-rare earth complexes display the typical luminescence emission peaks under the excitation wavelength of 330 nm. From the decay curve, the short lifetime (about 0.89 ms) is observed for (PFSi-IPDI)-Tb(Ⅲ)-Phen (0.6 mol/L). Moreover, these luminescent polymer-rare earth complexes possess superior thermal stability (T5 > 195 °C). All the interesting results suggest the potential application of the luminescent polymer-rare earth complexes in green-emitting luminescent materials under high temperature.

Low temperature luminescence and charge carrier trapping in a cryogenic scintillator Li{sub 2}MoO{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Spassky, D.A., E-mail: deris2002@mail.ru [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119991 Moscow (Russian Federation); Nagirnyi, V. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Savon, A.E. [Skobeltsyn Institute of Nuclear Physics, Moscow State University, 119991 Moscow (Russian Federation); Kamenskikh, I.A. [Physics Faculty, Moscow State University, 119991 Moscow (Russian Federation); Barinova, O.P.; Kirsanova, S.V. [D. Mendeleyev University of Chemical Technology of Russia, 125047 Moscow (Russian Federation); Grigorieva, V.D.; Ivannikova, N.V.; Shlegel, V.N. [Nikolaev Institute of Inorganic Chemistry, SB RAS, 630090 Novosibirsk (Russian Federation); Aleksanyan, E. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); A.Alikhanyan National Science Laboratory, 2 Br. Alikhanyan Str., 0036 Yerevan (Armenia); Yelisseyev, A.P. [Sobolev Institute of Geology and Mineralogy, SB RAS, 630090 Novosibirsk (Russian Federation); Belsky, A. [Institute of Light and Matter, CNRS, University Lyon1, 69622 Villeurbanne (France)

2015-10-15

The luminescence and optical properties of promising cryogenic scintillator Li{sub 2}MoO{sub 4} were studied in the temperature region of 2–300 K. The data on luminescence spectra and decay characteristics, excitation spectra, thermostimulated luminescence curves and spectra as well as transmission and reflectivity spectra are presented for the single crystals grown by two different procedures, the conventional Czochralski method and the low-temperature gradient Czochralski technique. The bandgap of Li{sub 2}MoO{sub 4} is estimated from the analysis of transmission, luminescence excitation and reflectivity spectra. Up to three luminescence bands with the maxima at 1.98, 2.08 and 2.25 eV are detected in the emission spectra of crystals and their origin is discussed. In the thermoluminescence curves of both studied crystals, two high-intensity peaks were observed at 22 and 42 K, which are ascribed to the thermal release of self-trapped charge carriers. The coexistence of self-trapped electrons and holes allows one to explain the poor scintillation light yield of Li{sub 2}MoO{sub 4} at low temperatures. - Highlights: • Single crystals of Li{sub 2}MoO{sub 4} were grown by two methods. • The transparency cutoff (~4.3 eV) and bandgap values (<4.9 eV) are estimated. • The emission 2.08 eV is ascribed to self-trapped excitons and quenches at T>7 K. • Shallow traps considerably influence the energy transfer to emission centres. • Co-existence of self-trapped holes and electrons results in a low light yield.

Investigations on the homogeneity of silica glass and on the order of X-amorphous silica by luminescence measurements

International Nuclear Information System (INIS)

Boden, G.

1982-08-01

Silica glasses melted from crystalline SiO 2 were exposed to ionizing radiation. At room temperature the spatial intensity distribution of the emitted luminescent radiation has been recorded by means of photographic or autoradiographic materials. Thereby schlieren and inhomogeneities are made visible and information is obtained on the melting process of the crystalline SiO 2 . Synthetic fused silica made from SiCl 4 shows no luminescent radiation. Depending on the penetration depth of the ionizing radiation the bulk or the surface of the sample can be studied. The decay curves of the integral luminescence intensity yield data on inhomogeneities in the silica glass leading to conclusions on order state and structure. The luminescence intensity and its half-life are a measure for the inhomogeneity of the silica glass and the existence of so-called 'preordered states'. This connection between luminescence intensity and the order state is found also with other X-amorphous SiO 2 modifications: silica gel, precipitated silicic acids, porous SiO 2 glasses, aerosil, thin SiO 2 layers, mechanically activated quartz: whereas no luminescence phenomena occur in disordered nearly ideally amorphous SiO 2 species, the luminescence increases with increasing order degree of the SiO 2 network and attains a high intensity in the case of the crystalline SiO 2 modifications quartz and cristobalite

On the shape of continuous wave infrared stimulated luminescence signals from feldspars: A case study

DEFF Research Database (Denmark)

Pagonis, V.; Jain, Mayank; Thomsen, Kristina Jørkov

2014-01-01

The continuous-wave IRSL (CW-IRSL) signals from feldspars are known to decay in a non-exponential manner, and their exact mathematical description is of great importance in dosimetric and dating studies. This paper investigates the possibility of fitting experimental CW-IRSL curves from a variety...... to guide future modeling work on luminescence processes in feldspars. Small statistical differences were found between K-rich and Na-rich fractions of the same sample. However, the experimental data shows that the parameters depend on the irradiation dose, but do not depend on the time elapsed after...

Luminescence imaging using radionuclides: a potential application in molecular imaging

International Nuclear Information System (INIS)

Park, Jeong Chan; Il An, Gwang; Park, Se-Il; Oh, Jungmin; Kim, Hong Joo; Su Ha, Yeong; Wang, Eun Kyung; Min Kim, Kyeong; Kim, Jung Young; Lee, Jaetae; Welch, Michael J.; Yoo, Jeongsoo

2011-01-01

Introduction: Nuclear and optical imaging are complementary in many aspects and there would be many advantages when optical imaging probes are prepared using radionuclides rather than classic fluorophores, and when nuclear and optical dual images are obtained using single imaging probe. Methods: The luminescence intensities of various radionuclides having different decay modes have been assayed using luminescence imaging and in vitro luminometer. Radioiodinated Herceptin was injected into a tumor-bearing mouse, and luminescence and microPET images were obtained. The plant dipped in [ 32 P]phosphate solution was scanned in luminescence mode. Radio-TLC plate was also imaged in the same imaging mode. Results: Radionuclides emitting high energy β + /β - particles showed higher luminescence signals. NIH3T6.7 tumors were detected in both optical and nuclear imaging. The uptake of [ 32 P]phosphate in plant was easily followed by luminescence imaging. Radio-TLC plate was visualized and radiochemical purity was quantified using luminescence imaging. Conclusion: Many radionuclides with high energetic β + or β - particles during decay were found to be imaged in luminescence mode due mainly to Cerenkov radiation. 'Cerenkov imaging' provides a new optical imaging platform and an invaluable bridge between optical and nuclear imaging. New optical imaging probes could be easily prepared using well-established radioiodination methods. Cerenkov imaging will have more applications in the research field of plant science and autoradiography.

Correction of dynamic time-activity curves for gamma-camera dead time, radiotracer delivery, and radioactive decay: special considerations with ultrashort-lived radioisotopes

International Nuclear Information System (INIS)

Kuruc, A.; Zimmerman, R.E.; Treves, S.

1985-01-01

Time-vs.-activity curves obtained by using ultrashort-lived radioisotopes often need to be corrected for the effects of gamma-camera dead time and physical decay. Count loss due to gamma-camera dead time can be monitored by using an electronic oscillator incorporated into the gamma camera. Two algorithms that use this information to correct time-activity curves are discussed. It is also shown that the effect of physical decay on a time-activity curve is dependent on the time course of delivery of the radioisotope to the organ of interest. A mathematical technique that corrects physical decay is described

Uranyl fluoride luminescence in acidic aqueous solutions

International Nuclear Information System (INIS)

Beitz, J.V.; Williams, C.W.

1996-01-01

Luminescence emission spectra and decay rates are reported for uranyl species in acidic aqueous solutions containing HF or added NaF. The longest luminescence lifetime, 0.269 ± 0.006 ms, was observed from uranyl in 1 M HF + 1 M HClO 4 at 296 K and decreased with increasing temperature. Based on a luminescence dynamics model that assumes equilibrium among electronically excited uranyl fluoride species and free fluoride ion, this long lived uranyl luminescence in aqueous solution is attributed primarily to UO 2 F 2 . Studies on the effect of added LiNO 3 or Na 2 WO 4 ·2H 2 O showed relatively weak quenching of uranyl fluoride luminescence which suggests that high sensitivity determination of the UF 6 content of WF 6 gas should be feasible via uranyl luminescence analysis of hydrolyzed gas samples of impure WF 6

Discuss on luminescence dose data analysis technology

International Nuclear Information System (INIS)

Ma Xinhua; Xiao Wuyun; Ai Xianyun; Shi Zhilan; Liu Ying

2009-01-01

This article describes the development of luminescence dose data measurement and processing technology. General design planning of luminescence dose data measurement and processing technology is put forward with the diverse demands. The emphasis is focused on dose data processing method, luminescence curve analysis method, using of network, mechanics of communication among computers, data base management system of individual dose in this paper. The main methods and skills used in this technology as well as their advantages are also discussed. And it offers general design references for development luminescence dose data processing software. (authors)

Synthesis and characterization of (Lu{sub 1−x−y}Y{sub x}Ce{sub y}){sub 2}SiO{sub 5} luminescent powders with fast decay time

Energy Technology Data Exchange (ETDEWEB)

Aburto-Crespo, M. [Programa de Posgrado en Física de Materiales CICESE-UNAM, Km. 107 Carretera Tij-Ens, Ensenada, B. C. 22860, México (Mexico); Hirata, G.A., E-mail: hirata@cnyn.unam.mx [Centro de Nanociencias y Nanotecnología-Universidad Nacional Autónoma de México, Km. 107 Carretera Tijuana-Ensenada, Ensenada, B. C. 22860, México (Mexico); McKittrick, J. [University of California at San Diego, La Jolla, CA 92093-0411 (United States)

2013-04-15

The structural and luminescent properties of blue-emitting (Lu{sub 1−x−y}Y{sub x}Ce{sub y}){sub 2}SiO{sub 5} (0.1≤x≤0.4, y=0.05, 0.005) phosphors prepared by combustion synthesis and post-annealed at 1200 °C for different annealing times are reported. X-ray diffraction analysis revealed the formation of a (Lu,Y){sub 2}SiO{sub 5} solid solution as a majority phase with small traces of a residual phase that was identified as Lu{sub 2}SiO{sub 7}. Under long-UV excitation, the powders yield a very bright blue-emission consisting of two bands with maximum emissions located at λ=405 nm and λ=440 nm, both corresponding to the Ce{sup 3+} allowed transitions {sup 2}D{sub 3/2}→{sup 2}F{sub 5/2} and {sup 2}D{sub 5/2}→{sup 2}F{sub 7/2}, respectively. Moreover, luminescence decay times of 38–45 ns were measured, which depend on the composition, making these powders excellent candidates for application as scintillators in medical imaging. -- Highlights: ► A facile technique to fabricate (Lu,Y)-oxyorthosilicate nanophosphors is presented. ► The structural and excellent luminescent properties including excitation, emission and short decay times are reported. ► The Ce-doped oxyorthosilicates nanophosphors present a fast decay time of the order of 38–45 ns.

The effect of pre-dose on thermally and optically stimulated luminescence from α-Al2O3:C,Mg and α-Al2O3:C.

Science.gov (United States)

Kalita, J M; Chithambo, M L

2018-06-15

We report the effect of pre-dose on the thermoluminescence (TL) and optically stimulated luminescence (OSL) dose response of α-Al 2 O 3 :C,Mg and α-Al 2 O 3 :C. Before any luminescence measurement, the samples were irradiated with different doses, namely 100, 500 and 1000 Gy to populate the deep electron traps. This is the pre-dose. The results from TL and OSL studies are compared with results from samples used without any pre-measurement dose. The TL glow curves and OSL decay curves of α-Al 2 O 3 :C,Mg recorded after pre-doses of 100, 500 and 1000 Gy are identical to those from a sample used without any pre-dose. Further, the TL and OSL dose response of all α-Al 2 O 3 :C,Mg samples are similar regardless of pre-dose. In comparison, the TL glow curves and OSL decay curves of α-Al 2 O 3 :C are influenced by pre-dose. We conclude that the differences in the TL and OSL dose response of various pre-dosed samples of α-Al 2 O 3 :C are due to the concentration of charge in the deep traps. On the other hand, owing to the lower concentration of such deep traps in α-Al 2 O 3 :C,Mg, the TL or OSL dose responses are not affected by pre-dose in this material. Copyright © 2018 Elsevier Ltd. All rights reserved.

Effect of temperature on the luminescence of Sm{sup 3+} ions in YAM crystals

Energy Technology Data Exchange (ETDEWEB)

Kaczkan, M. [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland); Boruc, Z., E-mail: z.boruc@stud.elka.pw.edu.pl [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland); Turczyński, S. [Institute of Electronic Materials Technology, ul. Wólczyńska 133, 01-919 Warsaw (Poland); Malinowski, M. [Institute of Microelectronics and Optoelectronics PW, ul. Koszykowa 75, 00-662 Warsaw (Poland)

2014-11-05

Highlights: • Different concentration Sm{sup 3+}-doped Y{sub 4}Al{sub 2}O{sub 9} crystals are fabricated by μ-pulling down method. • Thermally activated {sup 4}F{sub 3/2} → {sup 6}H{sub 5/2} emission of Sm{sup 3+} in YAM is studied. • Temperature dependent quenching mechanism of the {sup 4}G{sub 5/2} luminescence is proposed. - Abstract: The spectroscopic features of samarium Sm{sup 3+} activated Y{sub 4}Al{sub 2}O{sub 9} (YAM) crystals are presented and discussed. Temperature sensing properties of Sm{sup 3+}:YAM phosphor was demonstrated over the 300–1200 K range. Temperature dependent luminescence spectra and decay curves for the {sup 4}G{sub 5/2} level of Sm{sup 3+} in YAM were measured. Ratio of the fluorescence intensities arising from the two close lying {sup 4}F{sub 3/2} and {sup 4}G{sub 5/2} levels (with energy separation of ΔE ∼ 1000 cm{sup −1}) followed a straight line pattern, which confirms the Boltzmann distribution of the population, and can be used to measure temperature. The lifetime for the {sup 4}G{sub 5/2} level in 1% Sm doped sample decreases from 1.65 to 0.08 ms with heating from room temperature to 1200 K. This behavior of decays is discussed in terms of radiative and multiphonon decays as well as cross-relaxation dependence on temperature.

Test of the nonexponential deviations from decay curve of 52V using continuous kinetic function method

International Nuclear Information System (INIS)

Tran Dai Nghiep; Vu Hoang Lam; Vo Tuong Hanh; Do Nguyet Minh; Nguyen Ngoc Son

1995-01-01

Present work is aimed at a formulation of an experimental approach to search the proposed nonexponential deviations from decay curve and at description of an attempt to test them in case of 52 V. Some theoretical description of decay processes are formulated in clarified forms. A continuous kinetic function (CKF) method is described for analysis of experimental data and CKF for purely exponential case is considered as a standard for comparison between theoretical and experimental data. The degree of agreement is defined by the factor of goodness. Typical deviations of oscillation behaviour of 52 V decay were observed in a wide range of time. The proposed deviation related to interaction between decay products and environment is researched. A complex type of decay is discussed. (authors). 10 refs., 4 figs., 2 tabs

X-ray excited luminescence of polystyrene composites loaded with SrF{sub 2} nanoparticles

Energy Technology Data Exchange (ETDEWEB)

Demkiv, T.M.; Halyatkin, O.O.; Vistovskyy, V.V. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine); Hevyk, V.B. [Ivano-Frankivsk National Technical University of Oil and Gas, 15 Karpatska St., 76019 Ivano-Frankivsk (Ukraine); Yakibchuk, P.M. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine); Gektin, A.V. [Institute for Scintillation Materials, NAS of Ukraine, 60 Lenina Ave, 61001 Kharkiv (Ukraine); Voloshinovskii, A.S. [Ivan Franko National University of Lviv, 8a Kyryla i Mefodiya St., 79005 Lviv (Ukraine)

2017-03-01

The polystyrene film nanocomposites of 0.3 mm thickness with embedded SrF{sub 2} nanoparticles up to 40 wt% have been synthesized. The luminescent and kinetic properties of the polystyrene composites with embedded SrF{sub 2} nanoparticles upon the pulse X-ray excitation have been investigated. The luminescence intensity of the pure polystyrene scintillator film significantly increases when it is loaded with the inorganic SrF{sub 2} nanoparticles. The film nanocomposites show fast (∼2.8 ns) and slow (∼700 ns) luminescence decay components typical for a luminescence of polystyrene activators (p-Terphenyl and POPOP) and SrF{sub 2} nanoparticles, respectively. It is revealed that the fast decay luminescence component of the polystyrene composites is caused by the excitation of polystyrene by the photoelectrons escaped from the nanoparticles due to photoeffect, and the slow component is caused by reabsorption of the self-trapped exciton luminescence of SrF{sub 2} nanoparticles by polystyrene.

The nature of unusual luminescence in natural calcite, CaCO3

Energy Technology Data Exchange (ETDEWEB)

Gaft, M.; Nagli, L.; Panczer, G.; Waychunas, G.; Porat, N.

2008-11-01

The unusual luminescence of particular varieties of natural pink calcite (CaCO{sub 3}) samples was studied by laser-induced time-resolved luminescence spectroscopy at different temperatures. The luminescence is characterized by intense blue emission under short-wave UV lamp excitation with an extremely long decay time, accompanied by pink-orange luminescence under long wave UV excitation. Our investigation included optical absorption, natural thermostimulated luminescence (NTL) and Laser-Induced Breakdown Spectroscopy (LIBS) studies. Two luminescence centers were detected: a narrow violet band, with {lambda}{sub max} = 412 nm, {Delta} = 45 nm, two decay components of {tau}{sub 1} = 5 ns and {tau}{sub 2} = 7.2 ms, accompanied by very long afterglow, and an orange emission band with {lambda}{sub max} = 595 nm, {Delta} = 90 nm and {tau} = 5 ns. Both luminescence centers are thermally unstable with the blue emission disappearing after heating at 500 C, and the orange emission disappearing after heating at different temperatures starting from 230 C, although sometimes it is stable up to 500 C in different samples. Both centers have spectral-kinetic properties very unusual for mineral luminescence, which in combination with extremely low impurity concentrations, prevent their identification with specific impurity related emission. The most likely explanation of these observations may be the presence of radiation-induced luminescence centers. The long violet afterglow is evidently connected with trapped charge carrier liberation, with their subsequent migration through the valence band and ultimate recombination with a radiation-induced center responsible for the unusual violet luminescence.

Thermally stimulated luminescence in ZnMoO{sub 4} crystals

Energy Technology Data Exchange (ETDEWEB)

Degoda, V.Ya.; Kogut, Ya.P.; Moroz, I.M. [Kyiv National Taras Shevchenko University, MSP 03680 Kyiv (Ukraine); Danevich, F.A. [Institute for Nuclear Research, MSP 03680 Kyiv (Ukraine)

2017-03-15

Thermally stimulated luminescence in ZnMoO{sub 4} crystals after X-ray irradiation at temperatures 8 K, 85 K and 295 K was studied. A theoretical model of crystal phosphor with three types of traps (shallow, phosphorescent and deep) is proposed. Simple analytic solutions of the kinetic equations system describing localized electrons on the traps and holes on recombination centres were obtained by using approximations accepted in the classic theories of crystal phosphors. Analytical curves describing thermally stimulated luminescence were obtained. A substantial effect of the different traps concentrations ratios on the thermally stimulated luminescence and conductivity peaks shapes is shown. A good agreement of the theoretical curves with the experimental data for the thermally stimulated luminescence peak at 114 K is obtained.

A COMPREHENSIVE ANALYSIS OF SWIFT/X-RAY TELESCOPE DATA. IV. SINGLE POWER-LAW DECAYING LIGHT CURVES VERSUS CANONICAL LIGHT CURVES AND IMPLICATIONS FOR A UNIFIED ORIGIN OF X-RAYS

International Nuclear Information System (INIS)

Liang Enwei; Lue Houjun; Hou Shujin; Zhang Binbin; Zhang Bing

2009-01-01

By systematically analyzing the Swift/XRT light curves detected before 2009 July, we find 19 light curves that monotonously decay as a single power law (SPL) with an index of 1 ∼ 1.7 from tens (or hundreds) of seconds to ∼10 5 s post the gamma-ray burst (GRB) trigger. They are apparently different from the canonical light curves characterized by a shallow-to-normal decay transition. We compare the observations of the prompt gamma rays and the X-rays for these two samples of GRBs (SPL vs. canonical). No statistical difference is found in the prompt gamma-ray properties for the two samples. The X-ray properties of the two samples are also similar, although the SPL sample tends to have a slightly lower neutral hydrogen absorption column for the host galaxies and a slightly larger energy release compared with the canonical sample. The SPL X-ray Telescope (XRT) light curves in the burst frame gradually merge into a conflux, and their luminosities at 10 5 s are normally distributed at log L/ergs s -1 = 45.6 ± 0.5. The normal decay segment of the canonical XRT light curves has the same feature. Similar to the normal decay segment, the SPL light curves satisfy the closure relations and therefore can be roughly explained with external shock models. In the scenario that the X-rays are the afterglows of the GRB fireball, our results indicate that the shallow decay would be due to energy injection into the fireball and the total energy budget after injection for both samples of GRBs is comparable. More intriguing, we find that a prior X-ray emission model proposed by Yamazaki is more straightforward to interpret the observed XRT data. We show that the zero times (T 0 ) of the X-rays are 10 2 -10 5 s prior to the GRB trigger for the canonical sample, and satisfy a log-normal distribution. The negligible T 0 's of the SPL sample are consistent with being the tail of T 0 distributions at low end, suggesting that the SPL sample and the canonical sample may be from a same

ZnO Luminescence and scintillation studied via photoexcitation, X-ray excitation, and gamma-induced positron spectroscopy

Science.gov (United States)

Ji, J.; Colosimo, A. M.; Anwand, W.; Boatner, L. A.; Wagner, A.; Stepanov, P. S.; Trinh, T. T.; Liedke, M. O.; Krause-Rehberg, R.; Cowan, T. E.; Selim, F. A.

2016-08-01

The luminescence and scintillation properties of ZnO single crystals were studied by photoluminescence and X-ray-induced luminescence (XRIL) techniques. XRIL allowed a direct comparison to be made between the near-band emission (NBE) and trap emissions providing insight into the carrier recombination efficiency in the ZnO crystals. It also provided bulk luminescence measurements that were not affected by surface states. The origin of a green emission, the dominant trap emission in ZnO, was then investigated by gamma-induced positron spectroscopy (GIPS) - a unique defect spectroscopy method that enables positron lifetime measurements to be made for a sample without contributions from positron annihilation in the source materials. The measurements showed a single positron decay curve with a 175 ps lifetime component that was attributed to Zn vacancies passivated by hydrogen. Both oxygen vacancies and hydrogen-decorated Zn vacancies were suggested to contribute to the green emission. By combining scintillation measurements with XRIL, the fast scintillation in ZnO crystals was found to be strongly correlated with the ratio between the defect luminescence and NBE. This study reports the first application of GIPS to semiconductors, and it reveals the great benefits of the XRIL technique for the study of emission and scintillation properties of materials.

Single fiber temperature probe configuration using anti-Stokes luminescence from Cr:GdAlO3

Science.gov (United States)

Eldridge, Jeffrey I.

2018-06-01

Single-photon excitation of anti-Stokes-shifted emission from a thermographic phosphor allows operation of a luminescence decay-based single fiber temperature probe with negligible interference from background fiber-generated Raman scattering. While single fiber probe configurations for luminescence-based fiber optic thermometers offer advantages of simple design, compactness, and superior emission light collection efficiency, their effective use has been limited by interference from Raman scattering in the fiber probe and excitation delivery fiber that produces distortion of the luminescence decay that follows the excitation pulse. The near elimination of interference by background fiber-generated Raman scattering was demonstrated by incorporating a Cr-doped GdAlO3 (Cr:GdAlO3) thermographic phosphor as the sensing element at the end of a single fiber luminescence decay-based thermometer and detecting anti-Stokes-shifted luminescence centered at 542 or 593 nm produced by 695 nm excitation. Measurements were performed using both silica (up to 1150 °C) and single-crystal YAG (up to 1200 °C) fiber-based thermometers. Selection of emission detection centered at 542 nm greatly benefited the YAG fiber probe measurements by practically eliminating detection of otherwise significant luminescence from Cr3+ impurities in the YAG fiber. For both the silica and YAG fiber probes, the relative benefit of adopting single-photon excitation of anti-Stokes-shifted luminescence was evaluated by comparison with results obtained by conventional 532 nm excitation of Stokes-shifted luminescence.

Luminescence and decay kinetic mechanism of Pr.sup.3+./sup. centre in Lu.sub.0.8./sub.Sc.sub.0.2./sub.BO.sub.3./sub. host

Czech Academy of Sciences Publication Activity Database

Wu, Y.; Jarý, Vítězslav; Ren, G.; Nikl, Martin; Ding, D.; Pan, S.; Yang, F.

539-540, JUN (2012), s. 35-38 ISSN 0009-2614 R&D Projects: GA MŠk LH12185 Institutional research plan: CEZ:AV0Z10100521 Keywords : borate * luminescence * excited state ionization * Pr 3+ * decay kinetics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.145, year: 2012

Novel lanthanide doped micro- and mesoporous solids. Characterization of ion-host-interactions, species distribution and luminescence properties using time-resolved luminescence spectroscopy; Neuartige Lanthanoid-dotierte mikro- und mesoporoese Feststoffe. Charakterisierung von Ion-Wirt-Wechselwirkungen, Speziesverteilung und Lumineszenzeigenschaften mittels zeitaufgeloester Lumineszenzspektroskopie

Energy Technology Data Exchange (ETDEWEB)

Gessner, Andre

2010-12-15

In this work lanthanide-doped microporous zeolites, microporous-mesoporous hybrid materials and mesoporous silicates were investigated regarding their luminescence properties and the ion-host-interactions using time-resolved luminescence spectroscopy. Thereby, time-resolved emission spectra (TRES) provide information in the wavelength and time domain. For the analysis of the TRES a broad set of analytic methods was applied and thus a corresponding ''toolbox'' developed. Fitting of the luminescence decays was performed with a discrete number of exponentials and supported by luminescence decay times distributions. Time-resolved area normalized emission spectra (TRANES), an advancement of TRES, could be used for the determination of the number of emissive lanthanide species in porous materials for the first time. Calculation of the decay-associated spectra (DAS) allowed the correlation of spectral information with luminescence decay times and thus delivered the luminescence spectra of the different europium species. For europium(III) we could use in addition the time-dependent asymmetry ratio and spectral evolution of the {sup 5}D{sub 0}-{sup 7}F{sub 0}-transition with time to obtain further information about the distribution of the lanthanide ions in the host material. Luminescence decay times and spectra allowed conclusions on the number of OH-oscillators in and the symmetry of the first coordination sphere. For the microporous and microporous-mesoporous materials were found different lanthanide species, which were characterized by the above mentioned methods. These lanthanide species can be found on different positions in the host material. One position is located deep in the pore system. Here, lanthanide ions are hardly accessible for water and mainly coordinated by framework oxygens. This results in long luminescence decay times and distorted coordination spheres. The second position can be found near or on the outer surface or in the

Stimulation of Cysteine-Coated CdSe/ZnS Quantum Dot Luminescence by meso-Tetrakis (p-sulfonato-phenyl) Porphyrin

Science.gov (United States)

Parra, Gustavo G.; Ferreira, Lucimara P.; Gonçalves, Pablo J.; Sizova, Svetlana V.; Oleinikov, Vladimir A.; Morozov, Vladimir N.; Kuzmin, Vladimir A.; Borissevitch, Iouri E.

2018-02-01

Interaction between porphyrins and quantum dots (QD) via energy and/or charge transfer is usually accompanied by reduction of the QD luminescence intensity and lifetime. However, for CdSe/ZnS-Cys QD water solutions, kept at 276 K during 3 months (aged QD), the significant increase in the luminescence intensity at the addition of meso-tetrakis (p-sulfonato-phenyl) porphyrin (TPPS4) has been observed in this study. Aggregation of QD during the storage provokes reduction in the quantum yield and lifetime of their luminescence. Using steady-state and time-resolved fluorescence techniques, we demonstrated that TPPS4 stimulated disaggregation of aged CdSe/ZnS-Cys QD in aqueous solutions, increasing the quantum yield of their luminescence, which finally reached that of the fresh-prepared QD. Disaggregation takes place due to increase in electrostatic repulsion between QD at their binding with negatively charged porphyrin molecules. Binding of just four porphyrin molecules per single QD was sufficient for total QD disaggregation. The analysis of QD luminescence decay curves demonstrated that disaggregation stronger affected the luminescence related with the electron-hole annihilation in the QD shell. The obtained results demonstrate the way to repair aged QD by adding of some molecules or ions to the solutions, stimulating QD disaggregation and restoring their luminescence characteristics, which could be important for QD biomedical applications, such as bioimaging and fluorescence diagnostics. On the other hand, the disaggregation is important for QD applications in biology and medicine since it reduces the size of the particles facilitating their internalization into living cells across the cell membrane.

Effect of particle size and morphology on the properties of luminescence in ZnWO4

International Nuclear Information System (INIS)

Lisitsyn, V.M.; Valiev, D.T.; Tupitsyna, I.A.; Polisadova, E.F.; Oleshko, V.I.; Lisitsyna, L.A.; Andryuschenko, L.A.; Yakubovskaya, A.G.; Vovk, O.M.

2014-01-01

We investigated pulsed photoluminescence and pulsed cathodoluminescence in ZnWO 4 crystals and composite materials based on dispersed powders of zinc tungstate in the polymer matrix. It is shown that the size of crystal particles affects the luminescence decay time in excitation by electron and laser radiation. The decay time obtained for the composite material with nanoparticles 25 nm and 100 nm in size is equal to 5 µs and 7 µs, respectively. Relative values of the light yield of composite containing zinc tungstate crystals in the form of rods are found to be larger in comparison with crystallites in the form of grains. The mechanisms of luminescence recombination in laser and electron excitation are discussed. - Highlights: • Pulsed photoluminescence and pulsed cathodoluminescence spectra and decay kinetics of nano- and microcrystals of zinc tungstate in the organosilicic matrix compared to a single crystal were studied. • The luminescence decay kinetics and life-time of the excited state depend on the size of particles in the composite materials and on the type of excitation. • The probability of excitation of luminescence centers responsible for the band at 490 nm is higher which is apparently due to the larger capture cross-section and quantum yield

X-ray excited optical luminescence (XEOL) and its application to porous silicon

International Nuclear Information System (INIS)

Hill, D.A.

1998-09-01

X-ray Excited Optical Luminescence (XEOL) is investigated as a local structural probe of the light-emitting sites in porous silicon. A detailed microscopic model of the XEOL process in porous silicon is proposed. A central aspect of the technique is an assessment of the spatial separation between the primary photoionisation event and subsequent optical radiative recombination. By constructing a Monte Carlo simulation of hot electron propagation in silicon using both elastic and inelastic scattering cross-sections, the mean minimum range of luminescence excitation can be calculated. This range is estimated as 546±1A for the silicon K-edge (∼ 1839eV), but is reduced to 8.9±0.1A for the silicon L 2,3 -edge (∼ 99eV). From known porous silicon properties, it is concluded that this mean minimum range is comparable to the actual range of excitation. Hence, more localised structural information may be obtained from L 2,3 -edge XEOL measurements. This important difference between the two spectra has been neglected in previous studies. Simultaneous measurements of the XEOL and total electron yield (TEY) x-ray absorption spectra (XAS) have been conducted at both the silicon K-edge and L 2,3 -edge for various porous silicon samples and related materials. Measurements have been conducted at the Si K-edge on a rapid thermally oxidised (RTO) porous silicon sample. XEOL spectra yield two distinct luminescence bands in the visible region. From multi-bunch wavelength-selective XEOL measurements, it is concluded that there are blue luminescent defective silica sites together with a red luminescent site originating from silicon-like material. The spectral time decay curve under pulsed x-ray excitation gives two distinct decay components; one fast in the range of a few nanoseconds and the other slow in the range of microseconds. Time-resolved XEOL measurements in single-bunch mode show that the fast band mirrors the blue wavelength XEOL whereas the slow band correlates with the

Structure and luminescent investigation of new Ln(III)-TTA complexes containing N-methyl-ε-caprolactam as ligand

Energy Technology Data Exchange (ETDEWEB)

Borges, Alex Santos, E-mail: alexb@ifes.edu.br [Coordenadoria de Química e Biologia, IFES, Vitória, ES 29040-780 (Brazil); Caliman, Ewerton Valadares [Coordenadoria de Engenharia Metalúrgica, IFES, Vitória, ES 29040-780 (Brazil); Dutra, José Diogo L. [Departamento de Química Fundamental, UFPE, Recife, PE 50590-470 (Brazil); Da Silva, Jeferson G. [Departamento de Farmácia, UFJF, Governador Valadares, MG 35010-17 (Brazil); Araujo, Maria Helena, E-mail: maria.araujo@pq.cnpq.br [Departamento de Química, UFMG, Belo Horizonte, MG 31270-901 (Brazil)

2016-02-15

The synthesis and photoluminescent properties of Ln(III)-TTA complexes (Ln=Eu(III) and Sm(III) ions; TTA=3-thenoyltrifluoroacetonate) with N-methyl-ε-caprolactam (NMC) are reported. The Ln complexes were characterized by elemental analysis, complexometric titration with EDTA and infrared spectroscopy. The molecular structures of the [Eu(TTA){sub 3}(NMC)(H{sub 2}O)] and [Sm(TTA){sub 3}(NMC)(H{sub 2}O)]·H{sub 2}O compounds were determined by single crystal X-ray crystallography. In these structures, the three TTA molecules are coordinated to the metal in anionic form as bidentate ligands, while the H{sub 2}O and NMC molecules are coordinated to the metal in neutral form as monodentated ligands. The coordination polyhedron around the Ln(III) atom can be described as square antiprismatic molecular geometry. The geometry of the [Eu(TTA){sub 3}(NMC)(H{sub 2}O)] complex was optimized with the Sparkle/RM1 model for Ln(III) complexes, allowing analysis of intramolecular energy transfer processes of the Eu(III) compound. The spectroscopic properties of the 4f{sup 6} intraconfigurational transitions of the Eu(III) complex were then studied experimentally and theoretically. The low value of emission quantum efficiency of {sup 5}D{sub 0} emitting level (η) of Eu(III) ion (ca. 36%) is due to the vibrational modes of the water molecule that act as luminescence quenching. In addition, the luminescence decay curves, the experimental intensity parameters (Ω{sub λ}), lifetimes (τ), radiative (A{sub rad}) and non-radiative (A{sub nrad}) decay rates, theoretical quantum yield (q{sub cal}) were also determined and discussed. - Highlights: • New Ln-TTA complexes with lactam were obtained and their luminescence investigated. • Jablonsky diagram for the Eu(III) complex shows the main channel for the IET process. • Data confirm the potentiality of the Eu(III) complex to produce red luminescence. • LUMPAC has provided useful information on the luminescence of the Eu

Effect of high-dose irradiation on the optically stimulated luminescence of Al{sub 2}O{sub 3}:C

Energy Technology Data Exchange (ETDEWEB)

Yukihara, E.G. E-mail: yukihara@thor.phy.okstate.edu; Whitley, V.H.; McKeever, S.W.S. E-mail: swsm@okstate.edu; Akselrod, A.E.; Akselrod, M.S

2004-06-01

This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al{sub 2}O{sub 3}:C, principally on the shape of the OSL decay curve and on the OSL sensitivity. The effect of the degree of deep trap filling on the OSL was also studied by monitoring the sensitivity changes after doses of beta irradiation and after step-annealing of samples previously irradiated with high doses. The OSL response to dose shows a linear-supralinear-saturation behavior, with a decrease in the response for doses higher than those required for saturation. This behavior correlates with the sensitivity changes observed in the samples annealed only to 773 K, which show sensitization for doses up to 20-50 Gy and desensitization for higher doses. Data from the step-annealing study leads to the suggestion that the sensitization is caused by the filling of deep electron traps, which become thermally unstable at 1100-1200 K, whereas the desensitization is caused by the filling of deep hole traps, which become thermally unstable at 800-875 K, along with a concomitant decrease in the concentration of recombination centers (F{sup +}-centers). Changes in the shape of the OSL decay curves are also observed at high doses, the decay becoming faster as the dose increases. These changes in the OSL decay curves are discussed in terms of multiple overlapping components, each characterized by different photoionization cross-sections. However, using numerical solutions of the rate equations for a simple model consisting of a main trap and a recombination center, it is shown that the kinetics of OSL process may also be partially responsible for the changes in the OSL curves at high doses in Al{sub 2}O{sub 3}:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed.

Characterization and Luminescence Properties of Color-Tunable Dy3+-Doped BaY2ZnO5 Nanophosphors

Science.gov (United States)

Sonika; Khatkar, S. P.; Khatkar, Avni; Kumar, Rajesh; Taxak, V. B.

2015-01-01

Dy3+-doped BaY2ZnO5 nanophosphors were successfully synthesized by use of a solution combustion process. The effects of sintering temperature and dysprosium concentration on the structural and luminescence characteristics of the phosphors were investigated. X-ray diffraction (XRD) analysis confirmed the formation of pure orthorhombic BaY2ZnO5 with the space group Pbnm at 1100°C. Morphological investigation revealed spherical nanoparticles with smooth surfaces. The luminescence features of the nanophosphor were studied by use of photoluminescence excitation (PLE) and photoluminescence emission (PL), with luminescence decay curves and color ( x, y) coordinates. On excitation at 355 nm, BaY2ZnO5 nanophosphor doped with trivalent dysprosium ion emits white light as a mixture of blue (4F9/2 → 6H15/2) and yellow (4F9/2 → 6H13/2) emission. Concentration quenching is explained on the basis of cross-relaxation between intermediate Dy3+ states. Thus, BaY2ZnO5:Dy3+ nanophosphor may be suitable for producing efficient white light for ultraviolet-light-emitting diodes (UV-LEDs), fluorescent lamps, and a variety of optical display panels.

Emergency dose estimation using optically stimulated luminescence from human tooth enamel

International Nuclear Information System (INIS)

Sholom, S.; DeWitt, R.; Simon, S.L.; Bouville, A.; McKeever, S.W.S.

2011-01-01

Human teeth were studied for potential use as emergency Optically Stimulated Luminescence (OSL) dosimeters. By using multiple-teeth samples in combination with a custom-built sensitive OSL reader, 60 Co-equivalent doses below 0.64 Gy were measured immediately after exposure with the lowest value being 27 mGy for the most sensitive sample. The variability of OSL sensitivity, from individual to individual using multiple-teeth samples, was determined to be 53%. X-ray and beta exposure were found to produce OSL curves with the same shape that differed from those due to ultraviolet (UV) exposure; as a result, correlation was observed between OSL signals after X-ray and beta exposure and was absent if compared to OSL signals after UV exposure. Fading of the OSL signal was 'typical' for most teeth with just a few of incisors showing atypical behavior. Typical fading dependences were described by a bi-exponential decay function with 'fast' (decay time around of 12 min) and 'slow' (decay time about 14 h) components. OSL detection limits, based on the techniques developed to-date, were found to be satisfactory from the point of view of medical triage requirements if conducted within 24 h of the exposure.

Emergency dose estimation using optically stimulated luminescence from human tooth enamel

Energy Technology Data Exchange (ETDEWEB)

Sholom, S., E-mail: sergey.sholom@okstate.edu [Oklahoma State University, Stillwater, OK (United States); DeWitt, R. [Oklahoma State University, Stillwater, OK (United States); Simon, S.L.; Bouville, A. [National Cancer Institute, National Institutes of Health, Bethesda, MD (United States); McKeever, S.W.S. [Oklahoma State University, Stillwater, OK (United States)

2011-09-15

Human teeth were studied for potential use as emergency Optically Stimulated Luminescence (OSL) dosimeters. By using multiple-teeth samples in combination with a custom-built sensitive OSL reader, {sup 60}Co-equivalent doses below 0.64 Gy were measured immediately after exposure with the lowest value being 27 mGy for the most sensitive sample. The variability of OSL sensitivity, from individual to individual using multiple-teeth samples, was determined to be 53%. X-ray and beta exposure were found to produce OSL curves with the same shape that differed from those due to ultraviolet (UV) exposure; as a result, correlation was observed between OSL signals after X-ray and beta exposure and was absent if compared to OSL signals after UV exposure. Fading of the OSL signal was 'typical' for most teeth with just a few of incisors showing atypical behavior. Typical fading dependences were described by a bi-exponential decay function with 'fast' (decay time around of 12 min) and 'slow' (decay time about 14 h) components. OSL detection limits, based on the techniques developed to-date, were found to be satisfactory from the point of view of medical triage requirements if conducted within 24 h of the exposure.

Luminescence properties of common salt (NaCl available in Nigeria for use as accident dosimeter in radiological emergency situation

Directory of Open Access Journals (Sweden)

Janet Ayobami Ademola

2017-04-01

Full Text Available In the event of a radiological accident or attack, it is important to assess and quantify radiation dose to the population. This could be done using materials in the vicinity that are sensitive to ionizing radiation. Common salt (NaCl is known to be a sensitive thermoluminescence (TL phosphor. Luminescence properties of common salt (NaCl used in Nigeria were investigated using an automated luminescence reader Risø TL/OSL-DA-15, with attention focused more on the Optically Stimulated Luminescence (OSL. Strong radiation-induced TL and OSL signals were observed. The TL peaks occurred at about 100 °C, 240 °C and 280 °C. The dose response of both the TL and OSL signals showed a linear relationship. From the OSL pulse anneal curve with TL curve, a preheat temperature of 190 °C for 10 s was found adequate for the OSL measurements. There was no significant difference in the OSL decay for stimulation temperatures of 100 and 120 °C. Fading experiment over a storage period of 14 days showed about 13 and 3% decrease in the OSL signal of sample 1 and sample 2, respectively. The ratios of measured to given dose for dose recovery test were within ±19% of unity. Within the limit of error the samples could be used as a complementary emergency dosimeter in radiological accident situation.

Luminescence Properties of Surface Radiation-Induced Defects in Lithium Fluoride

Science.gov (United States)

Voitovich, A. P.; Kalinov, V. S.; Martynovich, E. F.; Novikov, A. N.; Runets, L. P.; Stupak, A. P.

2013-11-01

Luminescence and luminescence excitation spectra are recorded for surface radiation-induced defects in lithium fluoride at temperatures of 77 and 293 K. The presence of three bands with relatively small intensity differences is a distinctive feature of the excitation spectrum. These bands are found to belong to the same type of defects. The positions of the peaks and the widths of the absorption and luminescence bands for these defects are determined. The luminescence decay time is measured. All the measured characteristics of these surface defects differ from those of previously known defects induced by radiation in the bulk of the crystals. It is found that the luminescence of surface defects in an ensemble of nanocrystals with different orientations is not polarized. The number of anion vacancies in the surface defects is estimated using the polarization measurements. It is shown that radiative scattering distorts the intensity ratios of the luminescence excitation bands located in different spectral regions.

Optimising the separation of quartz and feldspar optically stimulated luminescence using pulsed excitation

International Nuclear Information System (INIS)

Ankjaergaard, C.; Jain, M.; Thomsen, K.J.; Murray, A.S.

2010-01-01

In luminescence dating, the two most commonly used natural minerals, quartz and feldspar, are exposed to different dose rates in the natural environment, and so record different doses. The luminescence signals also have different stabilities. For accurate dosimetry, the signals from these two minerals must be separated, either by physical separation of the mineral grains, or by instrumental separation of the luminescence signals. The luminescence signals from quartz and feldspar have different luminescence lifetimes under pulsed optical stimulation. This difference in lifetime can be used to discriminate between the two signals from a mixed quartz-feldspar sample. The purpose of this study is to identify optimum measurement conditions for the best separation of quartz OSL from that of feldspar in a mixed sample using pulsed stimulation and time-resolved OSL. We integrate the signal from 5 μs after the LEDs are switched off until just before the LEDs are switched on again, with the pulse on-time equal to the pulse off-time of 50 μs. By using only the initial interval of the pulsed OSL decay curve (equivalent to 0.2 s of CW-OSL using blue light at 50 mW cm -2 ) we find that the quartz to feldspar pulsed OSL intensity ratio is at a maximum. By using these parameters with an additional infrared (IR) stimulation at 175 o C before measurement (to further reduce the feldspar signal intensity), we obtain a factor of 25 enhancement in signal separation compared to that from a conventional prior-IR CW measurement. This ratio can be further improved if the counting window in the pulse off-time is restricted to detect between 20 and 50 μs instead of the entire off-period.

Optical spectroscopy and luminescence properties of Ho3+ doped zinc fluorophosphate (ZFP) glasses for green luminescent device applications

Science.gov (United States)

Reddy Prasad, V.; Damodaraiah, S.; Ratnakaram, Y. C.

2018-04-01

Ho3+ doped zinc fluorophosphate (ZFP) glasses with molar chemical compositions, (60-x) NH4H2PO4+20ZnO+10BaF2+10NaF+xHo2O3 (where x = 0.1, 0.3, 0.5, 1.0 and 1.5 mol%) were prepared by melt quenching technique. These glasses were characterized through physical, structural, optical, excitation, luminescence and decay curve analysis. From the absorption spectra, spectral intensities (fexp and fcal), Judd-Ofelt intensity parameters (Ω2, Ω4 and Ω6), radiative transition probabilities (AT), radiative lifetimes (τR) and branching ratios (βR) were evaluated for all Ho3+ doped ZFP glass matrices. From the photoluminescence spectra, peak stimulated emission cross-sections (σP) were calculated for all Ho3+ doped ZFP glasses. The Ho3+ doped ZFP glasses show strong green emission at 545 nm and red emission at 656 nm under excitation, 450 nm. The measured lifetimes (τmeas) of (5S2)5F4 level of Ho3+ doped ZFP glasses were obtained from decay profiles. The CIE color coordinates of Ho3+ doped ZFP glasses were calculated from emission spectra and 1.0 mol% of Ho3+ doped ZFP glass matrix gives green emission. Hence, these results confirm that the Ho3+ doped ZFP glasses could be considered as a promising candidate for visible green laser applications.

Intrinsic and defect related luminescence in double oxide films of Al–Hf–O system under soft X-ray and VUV excitation

Energy Technology Data Exchange (ETDEWEB)

Pustovarov, V.A., E-mail: vpustovarov@bk.ru [Ural Federal University, 19 Mira Street, 620002 Yekaterinburg (Russian Federation); Smirnova, T.P.; Lebedev, M.S. [Nikolaev Institute of Inorganic Chemistry, Siberian Branch of Russian Academy of Science, Novosibirsk 630090 (Russian Federation); Gritsenko, V.A. [Institute of Semiconductor Physics, Siberian Branch of Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation); Novosibirsk National Research University, 2 Pirogova Street, 630090 Novosibirsk (Russian Federation); Kirm, M. [Institute of Physics, University of Tartu, 14c Ravila, 50411 Tartu (Estonia)

2016-02-15

Low temperature time-resolved luminescence spectra in the region of 2.5–9.5 eV under soft X-ray excitation as well as time-resolved luminescence excitation spectra in the UV–VUV region (3.7–12 eV) of solid solutions Al{sub x}Hf{sub y}O{sub 1−x−y} thin films were investigated. The values of x and Al/Hf ratio were determined from X-ray photoelectron srectroscopy data. Hafnia films and films mixed with alumina were grown in a flow-type chemical vapor deposition reactor with argon as a carrier gas. In addition, pure alumina films were prepared by the atomic layer deposition method. A strong emission band with the peak position at 4.4 eV and with the decay time in the μs-range was revealed for pure hafnia films. The emission peak at 7.74 eV with short nanosecond decay kinetics was observed in the luminescence spectra for pure alumina films. These emission bands were ascribed to the radiative decay of self-trapped excitons (an intrinsic luminescence) in pure HfO{sub 2} and Al{sub 2}O{sub 3} films, respectively. Along with intrinsic host emission, defect related luminescence bands with a larger Stokes shift were observed. In the emission spectra of the solid solution films (x=4; 17; 20 at%) the intrinsic emission bands are quenched and only the luminescence of defects (an anion vacancies) was observed. Based on transformation of the luminescence spectra and ns-luminescence decay kinetics, as well as changes in the time-resolved luminescence and luminescence excitation spectra, the relaxation processes in the films of solid solution are discussed. - Highlights: • Low temperature time−resolved PL spectra were studied in a broad range (1.5−9.5 eV). • We carried out a luminescent control of point defects (anion vacancies) and self−trapped excitons. • We observed photoluminescence of excitons bound on defects. • We observed changes of photoluminescence properties with varying ratio components.

Cerium luminescence in nd0 perovskites

International Nuclear Information System (INIS)

Setlur, A.A.; Happek, U.

2010-01-01

The luminescence of Ce 3+ in perovskite (ABO 3 ) hosts with nd 0 B-site cations, specifically Ca(Hf,Zr)O 3 and (La,Gd)ScO 3 , is investigated in this report. The energy position of the Ce 3+ excitation and emission bands in these perovskites is compared to those of typical Al 3+ perovskites; we find a Ce 3+ 5d 1 centroid shift and Stokes shift that are larger versus the corresponding values for the Al 3+ perovskites. It is also shown that Ce 3+ luminescence quenching is due to Ce 3+ photoionization. The comparison between these perovskites shows reasonable correlations between Ce 3+ luminescence quenching, the energy position of the Ce 3+ 5d 1 excited state with respect to the host conduction band, and the host composition. - Graphical abstract: Ce 3+ decay times versus temperature for perovskites with nd 0 B-site cations.

The recombination channels of luminescence excitation in YAG:Yb single crystalline films

International Nuclear Information System (INIS)

Zakharko, Ya.M.; Luchechko, A.P.; Ubizskii, S.B.; Syvorotka, I.I.; Martynyuk, N.V.; Syvorotka, I.M.

2007-01-01

Absorption and emission spectra, luminescence decay kinetics and thermostimulated luminescence of X-ray irradiated YAG:Yb single crystalline films were studied. Two emission bands peaked at 420 and 488 nm have been detected in the investigated films. The strong thermal quenching of luminescence band at 488 nm was observed above 160 K. The influence of growth conditions and annealing in air on the lifetime of Yb 3+ ion excited state in the IR spectral region have been revealed. The recombination mechanisms of the f-f transition at Yb 3+ ion excitation, as well as the mechanism of lifetime shortening for the excited Yb 3+ luminescence have been discussed

Effects of nanostructuring on luminescence properties of SrS:Ce,Sm phosphor: An experimental and phenomenological study

Science.gov (United States)

Yazdanmehr, Mohsen; Sadeghi, Hossein; Tehrani, Masoud Kavosh; Hashemifar, Seyed Javad; Mahdavi, Mohammad

2018-01-01

In this work, we employ various experimental techniques to illustrate the effects of nanostructuring on improvement of the luminescence properties of the polycrystalline SrS co-activated by cerium and samarium dopants (SrS : Ce , Sm). The nano and microstructure SrS : Ce , Sm powders were synthesized by the co-precipitation and solid state diffusion methods, respectively, followed by the spark plasma sintering (SPS) process to densify powders into pellet shape. It is observed that the photo-luminescence (PL), radio-luminescence (RL), and optically stimulated luminescence (OSL) emission intensity of the nanostructure samples are significantly improved with respect to the microstructure samples. Moreover, by using an accurate photomultiplier tube, we measured the CW-OSL decay curves of the samples to demonstrate much higher and faster sensitivity of the nanostructure SrS : Ce , Sm for in-flight and online OSL radiation dosimetry. The obtained absorption and emission spectra are used for phenomenology of the electronic band structure of the SrS : Ce , Sm micro and nano-phosphors inside the band gap. The proposed phenomenological electronic structures are then used to clarify the role of Ce3+ and Sm3+ localized energy levels in the luminescence properties of the nano and microstructure samples. It is argued that electronic transitions from the 2T2g state of Ce3+ and the 4G5/2 state of Sm3+ have strong contribution to the PL and RL emission spectra, while in the OSL mechanism, the Sm3+ 4G5/2 state is mainly responsible for electrons trapping.

Time-resolved luminescence studies in hydrogen uranyl phosphate intercalated with amines

Energy Technology Data Exchange (ETDEWEB)

Novo, Joao Batista Marques [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil)]. E-mail: jbmnovo@quimica.ufpr.br; Batista, Fabio Roberto [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil); Cunha, Carlos Jorge da [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil); Dias, Lauro Camargo Jr. [Departamento de Quimica, Universidade Federal do Parana, CP 19081, 81531-990 Curitiba-PR (Brazil); Teixeira Pessine, Francisco Benedito [Instituto de Quimica, Universidade Estadual de Campinas, CP 6154, 13084-971 Campinas-SP (Brazil)

2007-05-15

Time-resolved luminescence decays of intercalated compounds of hydrogen uranyl phosphate (HUP) with p-toluidinium (HUPPT), benzylaminium (HUPBZ), {alpha}-methylbenzylaminium (HUPMBZ) and hydroxylaminium (HUPHAM) were studied. The prepared compounds belong to the tetragonal P4/ncc space group and showed 00 l reflections shifted to lower angles relative to HUP, indicating that the intercalation increases the c parameter of the unit cell. The luminescence decays of the compounds with 100% of intercalation ratio (HUPHAM and HUPBZ) were analyzed by Global Analysis, assuming Lianos' stretched exponential as the model function, which can be applied to compounds with restricted geometry and mobile donor and quencher molecules. It was remarkable that the luminescence decays showed that the quenching of the emission of the uranyl ions by the intercalated protonated amines is not restricted by low dimensionality of the host uranyl phosphate, and that a diffusion mechanism occurs. Benzylaminium cation efficiently quenches the excited energy of the uranyl ions at close distance, but the long-range and long-lifetime quenching is hindered. A different situation is found in the case of the small hydroxylaminium cation, where the long distance diffusion of the species is fast, playing an important role in the quenching of the excited uranyl ions at longer times.

Time-resolved luminescence studies in hydrogen uranyl phosphate intercalated with amines

International Nuclear Information System (INIS)

Novo, Joao Batista Marques; Batista, Fabio Roberto; Cunha, Carlos Jorge da; Dias, Lauro Camargo Jr.; Teixeira Pessine, Francisco Benedito

2007-01-01

Time-resolved luminescence decays of intercalated compounds of hydrogen uranyl phosphate (HUP) with p-toluidinium (HUPPT), benzylaminium (HUPBZ), α-methylbenzylaminium (HUPMBZ) and hydroxylaminium (HUPHAM) were studied. The prepared compounds belong to the tetragonal P4/ncc space group and showed 00 l reflections shifted to lower angles relative to HUP, indicating that the intercalation increases the c parameter of the unit cell. The luminescence decays of the compounds with 100% of intercalation ratio (HUPHAM and HUPBZ) were analyzed by Global Analysis, assuming Lianos' stretched exponential as the model function, which can be applied to compounds with restricted geometry and mobile donor and quencher molecules. It was remarkable that the luminescence decays showed that the quenching of the emission of the uranyl ions by the intercalated protonated amines is not restricted by low dimensionality of the host uranyl phosphate, and that a diffusion mechanism occurs. Benzylaminium cation efficiently quenches the excited energy of the uranyl ions at close distance, but the long-range and long-lifetime quenching is hindered. A different situation is found in the case of the small hydroxylaminium cation, where the long distance diffusion of the species is fast, playing an important role in the quenching of the excited uranyl ions at longer times

Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by nanosecond pulse of soft X-ray source and/or UV laser

International Nuclear Information System (INIS)

Bruza, Petr; Fidler, Vlastimil; Nikl, Martin

2011-01-01

The practical applicability of the rare-earth doped scintillators in high-speed detectors is limited by the slow decay components in the temporal response of a scintillator. The study of origin and properties of material defects that induce the slow decay components is of major importance for the development of new scintillation materials. We present a table-top, time-domain UV-VIS luminescence spectrometer, featuring extended time and input sensitivity ranges and two excitation sources. The combination of both soft X-ray/XUV and UV excitation source allows the comparative measurements of luminescence spectra and decay kinetics of scintillators to be performed under the same experimental conditions. The luminescence of emission centers of a doped scintillator can be induced by conventional N 2 laser pulse, while the complete scintillation process can be initiated by a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of 4 ns duration. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu 3 Al 5 O 12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of the doped Ce 3+ ions was studied under 2.88 nm (430 eV) XUV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3.68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d 2 transition of Ce 3+ is directly excited. Furthermore, YAG:Ce and LuAG:Ce single crystals luminescence decay profiles are compared and discussed.

Sub-ppb level detection of uranium using ligand sensitized luminescence

International Nuclear Information System (INIS)

Kumar, Satendra; Maji, S.; Joseph, M.; Sankaran, K.

2015-01-01

Uranyl ion (UO 2 2+ ) is known to exhibit weak luminescence in aqueous medium due to poor molar absorptivity and low quantum yield. In order to enhance the luminescence of uranyl ion in aqueous medium, luminescence enhancing reagents such as H 3 PO 4 , H 2 SO 4 , HClO 4 have been widely used. Like lanthanides, uranyl luminescence can also be sensitized by using some organic ligands. Pyridine 2,6-dicarboxylic acid (PDA) has shown enhancement of luminescence of uranyl in aqueous medium. Enhancement in intensity is due to sensitization of uranyl luminescence by PDA. In order to see the effect of non-aqueous medium, in this work, luminescence of uranyl-PDA complex has been studied in acetonitrile medium. More than one order luminescence enhancement has been observed compared to UO 2 2+ - PDA complex in aqueous medium. The lifetime of uranyl luminescence of the complex in acetonitrile medium is 90 μs which is very high compared to 10 μs in aqueous medium, suggesting that the luminescence enhancement is a result of reduction in non-radiative decay channels in acetonitrile medium. The large enhancement of uranyl luminescence of uranyl-PDA complex in acetonitrile medium can be used for ultra-trace level detection of uranium. Linearity in the luminescence intensity has been observed over the uranium concentration range of 5 to 80 ppb and the detection limit calculated using the criterion of 3 σ is ~ 0.2 ppb. (author)

A Correlation Between the Intrinsic Brightness and Average Decay Rate of Gamma-Ray Burst X-Ray Afterglow Light Curves

Science.gov (United States)

Racusin, J. L.; Oates, S. R.; De Pasquale, M.; Kocevski, D.

2016-01-01

We present a correlation between the average temporal decay (alpha X,avg, greater than 200 s) and early-time luminosity (LX,200 s) of X-ray afterglows of gamma-ray bursts as observed by the Swift X-ray Telescope. Both quantities are measured relative to a rest-frame time of 200 s after the gamma-ray trigger. The luminosity â€" average decay correlation does not depend on specific temporal behavior and contains one scale-independent quantity minimizing the role of selection effects. This is a complementary correlation to that discovered by Oates et al. in the optical light curves observed by the Swift Ultraviolet Optical Telescope. The correlation indicates that, on average, more luminous X-ray afterglows decay faster than less luminous ones, indicating some relative mechanism for energy dissipation. The X-ray and optical correlations are entirely consistent once corrections are applied and contamination is removed. We explore the possible biases introduced by different light-curve morphologies and observational selection effects, and how either geometrical effects or intrinsic properties of the central engine and jet could explain the observed correlation.

Luminescence characteristics of quartz from the Southern Kenyan Rift Valley: Dose estimation using LM-OSL SAR

International Nuclear Information System (INIS)

Choi, J.H.; Duller, G.A.T.; Wintle, A.G.; Cheong, C.-S.

2006-01-01

Linearly modulated (LM) optically stimulated luminescence (OSL) measurements have revealed that some sedimentary quartz samples from the Kenyan Rift Valley do not have a fast OSL component, but contain a medium component and several slow components. It was impossible to recover a known dose for these samples using the conventional single-aliquot regenerative-dose (SAR) procedure. The dose-response curves and continuous wave (CW) OSL decay curves for these samples showed several undesirable properties for dating. We have compared various luminescence characteristics of these samples with other quartz samples from elsewhere in the world for which the SAR procedure has been shown to be appropriate; the latter were dominated by a fast OSL component. The characteristics include photoionisation cross-sections for each component and the relative proportions of the different components in the initial and total OSL signals. It was found that those samples that had greater than 90% of the initial 0.8 s of their OSL signal from the fast component were suitable for dating using the conventional SAR protocol. A novel method of displaying the relative contributions of the different OSL components in a ternary diagram is proposed. The thermal stability of each component was investigated using pulse-annealing experiments. We then examined the possibility of applying an LM-OSL SAR protocol to samples that have a substantial medium component

Luminescent emission of LiF: Mg, Ti exposed to UV radiation; Emision luminiscente del LiF: Mg, Ti expuesto a la radiacion UV

Energy Technology Data Exchange (ETDEWEB)

Estrada G, A. [Estudiante de Facultad de Ciencias, UNAM, Circuito Exterior, 04500 Mexico D.F. (Mexico); Castano M, V.M. [Centro de Fisica Aplicada y Tecnologia Avanzada, UNAM, Campus Juriquilla, Queretaro (Mexico); Cruz Z, E.; Garcia F, F. [Instituto de Ciencias Nucleares UNAM, A.P. 70-543 Mexico D.F. (Mexico)

2002-07-01

It was investigated the luminescent emission stimulated by heat (Tl) of LiF: Mg, Ti crystals which were exposed to UV radiation coming from a mercury lamp. Since this crystal depends on the thermal history, it has been used a thermal treatment consisting of a baking at 380 C during one hour for each reading and they were irradiated with UV. The brilliance curves between 5 and 840 minutes of exposure in the face of UV light were obtained. An important loss in the response, starting from 150 minutes of irradiation was observed. Also the relative intensity of the brilliance curve decay when the crystals being stored in darkness and room temperature conditions, which is according to the results in the literature about. (Author)

Cooperative effects in CdSe/ZnS-PEGOH quantum dot luminescence quenching by a water soluble porphyrin

International Nuclear Information System (INIS)

Borissevitch, I.E.; Parra, G.G.; Zagidullin, V.E.; Lukashev, E.P.; Knox, P.P.; Paschenko, V.Z.; Rubin, A.B.

2013-01-01

In this work we report on the study of the interaction of CdSe/ZnS-PEGOH 570 Quantum Dot (QD) with negatively charged meso-tetrakis(p-sulfonato-phenyl)porphyrin (TPPS 4 ) using optical absorption and fluorescence spectroscopies accompanied with time resolved “single photon counting” and dynamic and resonance light scattering techniques. In the steady-state experiments the QD luminescence quenching by TPPS 4 was well approximated by a square law. In the time-resolved experiments we observed a typical multi-exponential luminescence decay curve, successfully fitted by a bi-exponential approximation. At QD interaction with porphyrin the time quenching of both components was described by a linear Stern–Volmer dependence. The discrepancy between Stern–Volmer dependences in the steady-state and time resolved experiments may be due to formation of mixed m(TPPS 4 )+n(QD) complexes, in which one TPPS 4 molecule can quench several excited QDs. This idea is in accordance with the dynamic and resonance light scattering data, which demonstrate an increase of the scattering particle size at the TPPS 4 addition to QD solutions. - Highlights: ► Quantum Dot luminescence quenching by TPPS porphyrin was studied in water solutions. ► The size of particles in QD solutions possessed increase at the TPPS4 addition. ► Quenching of the QD luminescence by TPPS4 is realized in contact QD–porphyrin complexes. ► The formation of mixed quantum dot–porphyrin aggregates takes place.

Luminescence and color center distributions in K3YB6O12:Ce3+ phosphor

International Nuclear Information System (INIS)

Yang, Li; Wan, Yingpeng; Weng, Honggen; Huang, Yanlin; Chen, Cuili; Seo, Hyo Jin

2016-01-01

Polycrystalline Ce 3+ -doped K 3 YB 6 O 12 (1–14 mol%) phosphors were prepared by facile chemical sol–gel synthesis. The phase formation of the phosphors was confirmed by x-ray powder diffraction (XRD) analysis. The photoluminescence excitation spectra (PLE), emission spectra (PL) and the luminescence decay curves were tested. Under the near-UV light, the phosphors present the emission from blue color to yellowish green due to the allowed 4 f  –5 d transitions of Ce 3+ ions. The absolute quantum efficiency (QE) of K 3 YB 6 O 12 :Ce 3+ can reach 53% under the excitation of near-UV light. The luminescence thermal quenching of the phosphor was investigated by the temperature-dependent spectra. The crystallographic site of Ce 3+ ions in the lattice was identified and discussed on the basis of luminescence characteristics and structural data. There is only one isolated Ce 3+ center occupying the Y(II) sites in the lightly doped samples presenting a typical doublet emission profile. While the Ce 3+ multi-centers could be created with the enhancement of the doping levels, which could induce the distinct red-shift of the spectra due to the dipole–dipole interactions. The result in this work could be useful for the further investigation of other rare earth ions in this host. (paper)

Luminescence and circularly polarized luminescence of macrocyclic Eu(III) and Tb(III) complexes embedded in xerogel and sol-gel SiO2 glasses

International Nuclear Information System (INIS)

Morita, M.; Rau, D.; Kai, T.

2002-01-01

Luminescence, time-resolved luminescence, circularly polarized luminescence (CPL) and decay profiles of Ln(III)(15-crownether-5) (Ln=Ce, Sm, Eu, Tb) and Tb(III)-(R),(S)-cyclen derivative complexes doped in xerogel and sol-gel silica glasses are measured at temperatures down to 10 K to characterize luminescence properties and the electronic structure in the excited states. Luminescence spectral profiles and calculation of crystal field parameters (B 0 (2) ,B 2 (2) ) in the 5 D 0 → 7 F J (J=1,2) transition give evidence of the fact that the pentagonal and planar structure of Eu(III) (15-crownether-5) does hold in xerogel and sol-gel glasses prepared at temperatures below 100 deg. C. As annealing temperatures are increased from 80 deg. C to 750 deg. C, Eu(III) complexes in sol-gel glasses are found to decompose gradually to SiO 2 :Eu 3+ . Tb(III)-(R) and (S)-cyclen derivative complexes in xerogel reveal at room temperature and 10 K sharp CPL spectra with luminescence dissymmetry factors g lum =-0.1 and 0.1, respectively. These complexes doped in sol-gel glasses represent luminescence characteristics of rare earth ions encapsulated in the nano-porous host

Study of the luminescence properties of a natural amazonite

Energy Technology Data Exchange (ETDEWEB)

Correcher, V., E-mail: v.correcher@ciemat.es [CIEMAT, Av. Complutense 22, Madrid 28040 (Spain); Garcia-Guinea, J. [Museo Nacional de Ciencias Naturales, CSIC, C/Jose Gutierrez Abascal 2, Madrid 28006 (Spain)

2011-09-15

Most gemstones, being natural materials (silicates, carbonates, phosphates, etc.), exhibit luminescence emission. This property could be potentially employed for personal dosimetry in the case of radiation accident or radiological terrorism where conventional monitoring has not been established. We, herein, report on the thermoluminescence (TL), radioluminescence (RL) and infra-red stimulated luminescence (IRSL) response of a well-characterised natural amazonite (KAlSi{sub 3}O{sub 8}) that, due to its bright blue-green colour when polished, is used as a gemstone. The luminescence emission wavelengths, intensities and thermal kinetics of the amazonite luminescence curves reveal that the ultraviolet band measured on amazonite aliquots is similar to other common K-rich feldspars. On this basis, one can conclude (i) association between twinning and the UV-blue TL emission can be related to structural defects located in the twin-domain boundaries where ionic alkali-self-diffusion, irreversible water losses and irreversible dehydroxylation processes can be involved. (ii) Amazonite exhibits a complex structure with several planar defects (twinning and exsolution interphases which can hold hydroxyl groups, water molecules, etc.) and point defects (impurities, Na, Pb, Mn, etc.) that can act as luminescence centres, and in fact, green and red emissions are respectively associated with the presence of Mn and Fe impurities. Finally, (iv) the thermal stability tests performed on the TL emission of the amazonite confirm a continuum in the trap distribution, i.e. progressive changes in the glow curve shape, intensity and temperature position of the maximum peak.

Hormesis response of marine and freshwater luminescent bacteria to metal exposure

Directory of Open Access Journals (Sweden)

KAILI SHEN

2009-01-01

Full Text Available The stimulatory effect of low concentrations of toxic chemicals on organismal metabolism, referred to as hormesis, has been found to be common in the widely used luminescence bioassay. This paper aims to study the hormesis phenomenon in both marine and freshwater luminescent bacteria, named Photobacterium phosphorem and Vibrio qinghaiensis. The effects of Cu (II, Zn (II, Cd (II and Cr (VI on luminescence of these two bacteria were studied for 0 to 75 minutes exposure by establishing dose- and time-response curves. A clear hormesis phenomenon was observed in all four testing metals at low concentrations under the condition of luminescence assays.

Optical spectroscopy and luminescence quenching of LuI3:Ce3+

International Nuclear Information System (INIS)

Birowosuto, M.D.; Dorenbos, P.; Haas, J.T.M. de; Eijk, C.W.E. van; Kraemer, K.W.; Guedel, H.U.

2006-01-01

Optical spectroscopy of LuI 3 doped with Ce 3+ using ultraviolet and visible light excitation is reported. LuI 3 host excitation and emission and 4f-5d excitation and emission of Ce 3+ are observed. An empirical model based on crystal field splitting was used to estimate the energy of the highest 4f-5d excitation band. The crystal field splitting and centroid shift were compared to those of LuCl 3 :Ce 3+ and LuBr 3 :Ce 3+ . Temperature dependence of X-ray excited luminescence spectra shows thermal quenching, whereas that of the decay curve of Ce 3+ emission excited at the lowest 5d band of Ce 3+ does not indicate the presence of quenching of Ce 3+ emission for temperature below 625K. The quenching in LuI 3 :Ce 3+ therefore occurs before the 5d Ce 3+ emission takes place

Sensitive luminescent determination of DNA using the terbium(III)-difloxacin complex

International Nuclear Information System (INIS)

Yegorova, Alla V.; Scripinets, Yulia V.; Duerkop, Axel; Karasyov, Alexander A.; Antonovich, Valery P.; Wolfbeis, Otto S.

2007-01-01

The interaction of the terbium-difloxacin complex (Tb-DFX) with DNA has been examined by using UV-vis absorption and luminescence spectroscopy. The Tb-DFX complex shows an up to 85-fold enhancement of luminescence intensity upon titration with DNA. The long decay times allow additional detection schemes like time-resolved measurements in microplate readers to enhance sensitivity by off-gating short-lived background luminescence. Optimal conditions are found at equimolar concentrations of Tb 3+ and DFX (0.1 or 1 μM) at pH 7.4. Under these conditions, the luminescence intensity is linearly dependent on the concentration of ds-DNAs and ss-DNA between 1-1500 ng mL -1 and 4.5-270 ng mL -1 , respectively. The detection limit is 0.5 ng mL -1 for ds-DNAs and 2 ng mL -1 for ss-DNA. The mechanism for the luminescence enhancement was also studied

The research of characteristic difference of selected frequency luminescence for desert sand

International Nuclear Information System (INIS)

Liu Chao; Wei Mingjian; Li Huhou

2011-01-01

The characters of selected frequency luminescence of four groups of samples from Badain Jaran desert are measured by BG2003 luminescence spectrograph. The measurement subjects include selected frequency optical stimulate luminescence spectrum, selected frequency thermoluminescence spectrum and the dose response curve. A double-peak map is obtained by the result from all groups of data and spectrum. The difference is emerged between each group. The optical stimulate luminescence and thermoluminescence is applied in the measurement process. The dispersion of photon count on every response wavelength is analyzed. Based on the analysis, a better result can be gained by selected frequency thermoluminescence. (authors)

Doping the dots: doped quantum dots for luminescent solar concentrators

NARCIS (Netherlands)

Eilers, J.J.

2015-01-01

In this thesis, synthesis methods for luminescent organically capped colloidal ZnSe QDs of different sizes, ranging from 4.0 to 7.5 nm are reported. These QDs are analyzed using TEM, absorption spectroscopy, photoluminescence measurements and temperature dependent photoluminescence decay

Time-resolved luminescence of Eu2+-aggregate centers in CsBr crystals

International Nuclear Information System (INIS)

Zorenko, Yu.V.; Turchak, R.M.; Voznjak, T.I.; Stryganjuk, G.B.

2005-01-01

The luminescence of Eu 2+ -V Cs dipole centers and CsEuBr 3 aggregate centers, as well as the features of the energy transfer to these centers by excitons have been studied in CsBr:Eu crystals by means of investigation of the time-resolved emission spectra and luminescence decay kinetics under excitation by synchrotron radiation at RT. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Cooperative effects in CdSe/ZnS-PEGOH quantum dot luminescence quenching by a water soluble porphyrin

Energy Technology Data Exchange (ETDEWEB)

Borissevitch, I.E., E-mail: iourib@ffclrp.usp.br [Departamento de Fisica, Faculdade de Filosofia Ciencia e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes 3900, Ribeirao Preto, SP (Brazil); Parra, G.G. [Departamento de Fisica, Faculdade de Filosofia Ciencia e Letras de Ribeirao Preto, Universidade de Sao Paulo, Av. Bandeirantes 3900, Ribeirao Preto, SP (Brazil); Zagidullin, V.E.; Lukashev, E.P.; Knox, P.P.; Paschenko, V.Z.; Rubin, A.B. [Department of Biophysics, Faculty of Biology, M.V. Lomonosov Moscow State University, Vorobyovy Gory, 119991 Moscow (Russian Federation)

2013-02-15

In this work we report on the study of the interaction of CdSe/ZnS-PEGOH 570 Quantum Dot (QD) with negatively charged meso-tetrakis(p-sulfonato-phenyl)porphyrin (TPPS{sub 4}) using optical absorption and fluorescence spectroscopies accompanied with time resolved 'single photon counting' and dynamic and resonance light scattering techniques. In the steady-state experiments the QD luminescence quenching by TPPS{sub 4} was well approximated by a square law. In the time-resolved experiments we observed a typical multi-exponential luminescence decay curve, successfully fitted by a bi-exponential approximation. At QD interaction with porphyrin the time quenching of both components was described by a linear Stern-Volmer dependence. The discrepancy between Stern-Volmer dependences in the steady-state and time resolved experiments may be due to formation of mixed m(TPPS{sub 4})+n(QD) complexes, in which one TPPS{sub 4} molecule can quench several excited QDs. This idea is in accordance with the dynamic and resonance light scattering data, which demonstrate an increase of the scattering particle size at the TPPS{sub 4} addition to QD solutions. - Highlights: Black-Right-Pointing-Pointer Quantum Dot luminescence quenching by TPPS porphyrin was studied in water solutions. Black-Right-Pointing-Pointer The size of particles in QD solutions possessed increase at the TPPS4 addition. Black-Right-Pointing-Pointer Quenching of the QD luminescence by TPPS4 is realized in contact QD-porphyrin complexes. Black-Right-Pointing-Pointer The formation of mixed quantum dot-porphyrin aggregates takes place.

The behavior of thermally and optically stimulated luminescence of SrAl2O4:Eu2+,Dy3+ long persistent phosphor after blue light illumination

International Nuclear Information System (INIS)

Chernov, V.; Melendrez, R.; Pedroza-Montero, M.; Yen, W.M.; Barboza-Flores, M.

2008-01-01

The behavior of afterglow (AG), thermoluminescence (TL), infrared stimulated luminescence (IRSL) and phototransferred TL (PTTL) under thermal and/or infrared (IR) stimulation in blue (470 nm) light illuminated at room temperature (RT) SrAl 2 O 4 :Eu 2+ , Dy 3+ is presented. The TL glow curve consists of four peaks with maxima at about 340, 430, 560 and 680 K. The 340 and 440 K peaks are described well by second order kinetics with activation energies of 0.83 and 1.05 eV, respectively. The AG decay is fitted by the Becquerel's law with exponent 1.5 and correlates well with the thermal emptying of the traps responsible for the 340 K peak. The 340 and 430 K TL peak traps are destroyed under IR (830 nm) stimulation creating IRSL. IR stimulation after illumination with blue light and preliminary heating restore partially the 340 and 430 K TL peaks by phototransfer from deeper traps. The shape of the IRSL decay curves depends strongly on the preheating temperature and is determined by simultaneous refilling of the 340 and 430 K TL traps and their reverse filling due to phototransfer from the deeper traps under IR stimulation. The obtained data are interpreted by the transformation of Eu 2+ and Dy 3+ to Eu 3+ and Dy 2+ under blue light illumination and their reverse transformation under thermal or IR stimulation. The Eu 2+ ions are the luminescent centers and the Dy 2+ centers are the IR sensitive traps responsible for the TL peaks, AG and IRSL

Luminescence properties and energy transfer processes in YAG:Yb,Er single crystalline films

International Nuclear Information System (INIS)

Zorenko, Yu.; Gorbenko, V.; Savchyn, V.; Batentschuk, M.; Osvet, A.; Brabec, C.

2013-01-01

The paper is dedicated to the study of the optical properties of YAG:Yb,Er single-crystalline films (SCF) grown by liquid phase epitaxy. The absorption, cathodoluminescence and time-resolved photoluminescence spectra and photoluminescence decay curves were measured for the SCFs with different doping levels of Er 3+ (from 0.6 to 4.2 at.%) and Yb 3+ (from 0.1 to 0.6 at.%). The spectra, excited by synchrotron radiation in the fundamental absorption range of the YAG and in the intraionic absorption bands of both dopants, reveal energy transfer from the YAG host to the Er 3+ and Yb 3+ ions and between these ions. -- Highlights: •Growth of YAG:Yb,Er single crystalline films by LPE method. •Peculiarities of luminescence of YAG:Yb,Er films with different Er–Yb content. •Yb–Er energy transfer processes in YAG hosts

Luminescent hybrid films obtained by covalent grafting of terbium complex to silica network

International Nuclear Information System (INIS)

Liu Fengyi; Fu Lianshe; Wang Jun; Liu Ze; Li Huanrong; Zhang Hongjie

2002-01-01

Luminescent hybrid thin films consisting of terbium complex covalently bonded to a silica-based network have been obtained in situ via a sol-gel approach. A new monomer, N-(4-benzoic acid-yl), N'-(propyltriethoxysilyl)urea (PABI), has been synthesized by grafting isocyanatopropyltriethoxysilane (ICPTES) to p-aminobenzoic acid and characterized by 1 H NMR, IR and MS. The monomer acts as a ligand for Tb 3+ ion and as a sol-gel precursor. Band emission from Tb 3+ ion due to an efficient ligand-to-metal energy transfer was observed by UV excitation. The decay curves of Tb 3+ in the hybrid films were measured. The energy difference between the triplet state energy of PABI and the 5 D 4 level of Tb 3+ ion falls in the exciting range to sensitize Tb 3+ ion fluorescence

Optically stimulated luminescence dosimetry with gypsum wallboard (drywall)

International Nuclear Information System (INIS)

Thompson, J. W.; Burdette, K. E.; Inrig, E. L.; Dewitt, R.; Mistry, R.; Rink, W. J.; Boreham, D. R.

2010-01-01

Gypsum wallboard (drywall) represents an attractive target for retrospective dosimetry by optically stimulated luminescence (OSL) in the event of a radiological accident or malicious use of nuclear material. In this study, wallboard is shown to display a radiation-induced luminescence signal (RIS) as well as a natural background signal (NS), which is comparable in intensity to the RIS. Excitation and emission spectra show that maximum luminescence intensity is obtained for stimulation with blue light-emitting diodes (470 nm) and for detection in the ultraviolet region (290-370 nm). It is necessary to decrease the optical stimulation power dramatically in order to adequately separate the RIS from the interfering background signal. The necessary protocols are developed for accurately measuring the absorbed dose as low as 500 mGy and demonstrate that the RIS decays logarithmically with storage time, with complete erasure expected within 1-4 d. (authors)

Anomalous fading of the TL, Blue-SL and IR-SL signals of fluorapatite

International Nuclear Information System (INIS)

Tsirliganis, N.; Polymeris, G.; Loukou, Z.; Kitis, G.

2006-01-01

The thermoluminescence (TL), blue stimulated luminescence (BSL) and infrared stimulated luminescence (IRSL) signals of fluorapatite (originating from Durango, Mexico) were measured and found to exhibit strong anomalous fading (AF). The experimentally obtained OSL and IRSL decay curves were transformed into pseudo-linear modulated (pseudo-LM) decay curves. The resulting glow-curve shaped pseudo-LM decay curves were analyzed using a deconvolution analysis, similar to the one used for the glow-curve deconvolution (GCD) of TL glow-curves. It was found that the pseudo-LM OSL and IRSL decay curves consist of two components named fast and slow, respectively, and their individual contribution was estimated. The AF of the remnant TL, BSL and IRSL as a function of the storage time was fitted using the tunneling model equations and the fading rate g, in terms of percentage per decade was evaluated. According to the obtained g values, the AF of the BSL and IRSL is stronger than that of the TL. The AF of the fast component of BSL and IRSL is almost the same. The AF of the slow component of IRSL is, by approximately a factor of 2, stronger than that of the BSL

Reconstruction of thermally quenched glow curves in quartz

International Nuclear Information System (INIS)

Subedi, Bhagawan; Polymeris, George S.; Tsirliganis, Nestor C.; Pagonis, Vasilis; Kitis, George

2012-01-01

The experimentally measured thermoluminescence (TL) glow curves of quartz samples are influenced by the presence of the thermal quenching effect, which involves a variation of the luminescence efficiency as a function of temperature. The real shape of the thermally unquenched TL glow curves is completely unknown. In the present work an attempt is made to reconstruct these unquenched glow curves from the quenched experimental data, and for two different types of quartz samples. The reconstruction is based on the values of the thermal quenching parameter W (activation energy) and C (a dimensionless constant), which are known from recent experimental work on these two samples. A computerized glow-curve deconvolution (CGCD) analysis was performed twice for both the reconstructed and the experimental TL glow curves. Special attention was paid to check for consistency between the results of these two independent CGCD analyses. The investigation showed that the reconstruction attempt was successful, and it is concluded that the analysis of reconstructed TL glow curves can provide improved values of the kinetic parameters E, s for the glow peaks of quartz. This also leads to a better evaluation of the half-lives of electron trapping levels used for dosimetry and luminescence dating.

Luminescence of Tb.sup.3+./sup.-doped high silica glass under UV and X-ray excitation

Czech Academy of Sciences Publication Activity Database

Chewpraditkul, W.; Shen, Y.; Chen, D.; Beitlerová, Alena; Nikl, Martin

2013-01-01

Roč. 35, č. 3 (2013), s. 426-430 ISSN 0925-3467 R&D Projects: GA MŠk LH12185 Institutional support: RVO:68378271 Keywords : Tb 3+ * luminescence * luminescence decays * porous silica glass * scintillation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.075, year: 2013 http://dx.doi.org/10.1016/j.optmat.2012.09.012

Temperature dependent luminescence and energy transfer properties of Na2SrMg(PO4)2:Eu2+, Mn2+ phosphors.

Science.gov (United States)

Geng, Dongling; Shang, Mengmeng; Zhang, Yang; Lian, Hongzhou; Lin, Jun

2013-11-21

Eu(2+) singly and Eu(2+)/Mn(2+) co-doped Na2SrMg(PO4)2 (NSMP) phosphors have been prepared via a high-temperature solid-state reaction process. Upon UV excitation of 260-360 nm, the NSMP:xEu(2+) phosphors exhibit a violet band located at 399 nm and a blue band centered at 445 nm, which originate from Eu(2+) ions occupying two different crystallographic sites: Eu(2+)(I) and Eu(2+)(II), respectively. Excitation wavelengths longer than 380 nm can selectively excite Eu(2+)(II) to emit blue light. Energy transfer processes in the Eu(2+)(I)-Eu(2+)(II) and Eu(2+)-Mn(2+) pairs have been observed and investigated by luminescence spectra and decay curves. The emission color of as-prepared samples can be tuned by changing the relative concentrations of Eu(2+) and Mn(2+) ions and adjusting the excitation wavelength. Under UV excitation of 323 nm, the absolute quantum yield of NSMP:0.005Eu(2+) is 91%, which is higher than most of the other Eu(2+)-doped phosphors reported previously. The temperature dependent luminescence properties and decay curves (4.3-450 K) of NSMP:Eu(2+) and NSMP:Eu(2+), Mn(2+) phosphors have been studied in detail. Thermal quenching of Eu(2+) has been observed while the emission band of Mn(2+) shows a blue-shift and an abnormal increase of intensity with increasing temperature. The unusual thermal quenching behavior indicates that the NSMP compound can serve as a good lattice host for Mn(2+) ions which can be used as a red-emitting phosphor. Additionally, the lifetimes for Eu(2+)(I) and Eu(2+)(II) increase with increasing temperatures.

Ion irradiation effect of alumina and its luminescence

Energy Technology Data Exchange (ETDEWEB)

Aoki, Yasushi; Yamamoto, Shunya; Naramoto, Hiroshi [Japan Atomic Energy Research Inst., Takasaki, Gunma (Japan). Takasaki Radiation Chemistry Research Establishment; My, N T

1997-03-01

The luminescence spectra of single crystalline alpha-alumina and ruby which has 0.02% of Cr{sub 2}O{sub 3} as a impurity, induced by 200 keV He{sup +} and Ar{sup +} irradiation were measured at room temperature as a function of irradiation dose. The analysis of the measured spectra showed the existence of three main luminescence features in the wavelength region of 250 to 350 nm, namely anionic color centers, F-center at 411 nm and F{sup +}-center at 330 nm and a band observed around 315 nm. As alpha-alumina was irradiated with He{sup +}, F-center and F{sup +}-center luminescence grew and decayed, but the behaviors of those were different from each other. It seems that a concentration quenching occurred on the F-center luminescence in the dose range above 1x10{sup 14} He/cm{sup 2}. Furthermore, F-center luminescence was strongly suppressed in ruby, compared with that in alumina. On the other hand, the luminescence band around 315 nm appeared only in the early stage of irradiation and did not show its growth part. The dose dependent behavior was similar to that of Cr{sup 3+} emission at 695 nm (R-line) in ruby in both cases of He{sup +} and Ar{sup +} irradiation. Based on the experimental results mentioned above, the processes of defect formation and excitation in alumina in the early stage of ion irradiation will be discussed. (author)

Optical absorption, luminescence, and energy transfer processes studies for Dy3+/Tb3+-codoped borate glasses for solid-state lighting applications

Science.gov (United States)

Lakshminarayana, G.; Kaky, Kawa M.; Baki, S. O.; Lira, A.; Caldiño, U.; Kityk, I. V.; Mahdi, M. A.

2017-10-01

By using melt quenching technique, good optical quality singly doped Dy3+ or Tb3+ and Dy3+/Tb3+-codoped borate glasses were synthesized and studied by optical absorption, excitation, emission and decay lifetimes curve analysis. Following the absorption spectrum, the evaluated Judd-Ofelt (J-O) intensity parameters (Ωλ (λ = 2, 4 and 6)) were used to calculate the transition probability (AR), the branching ratio (βR), and the radiative lifetime (τR) for different luminescent transitions such as 4I15/2 → 6H15/2, 4F9/2 → 6H15/2, 4F9/2 → 6H13/2, 4F9/2 → 6H11/2 and 4F9/2 → 6H9/2,6F11/2 for the 0.5 mol % singly Dy3+-doped glass. The βR calculated (65%) indicates that for lasing applications, 4F9/2 → 6H13/2 emission transition is highly suitable. For all the Dy3+/Tb3+-codoped glasses, Tb3+: 5D3→7F6 emission decay lifetime curves are found to be non-exponential in nature for different concentrations of Dy3+ codoping. Using the Inokuti-Hirayama model, these nonexponential decay curves were analyzed to identify the nature of the energy transfer (ET) processes and here the electric dipole-dipole interaction is dominant for the ET. Based on the excitation and emission spectra and decay lifetimes curve analysis, the cross relaxation and ET processes between Dy3+ and Tb3+ were confirmed. For the 0.5 mol % Tb3+ and 2.0 mol % Dy3+-codoped glass, the evaluated Tb3+→Dy3+ ET efficiency (η) is found to be 45% under 369 nm excitation. Further, for Tb3+/Dy3+ -codoped glasses, an enhancement of Tb3+ green emission is observed up to 1.5 mol % Dy3+ codoping, and this is due to the non-radiative resonant ET from Dy3+ to Tb3+ upon 395 nm excitation. For singly 0.5 mol % Dy3+ or 0.5 mol % Tb3+-doped glass, the calculated color coordinates (x,y) and correlated color temperatures (CCT) represent the neutral white or warm white light regions, whereas Dy3+/Tb3+-codoped glasses (x,y) and CCT values fall in the yellowish green region with respect to the different Dy3

A luminescence lifetime assisted ratiometric fluorimeter for biological applications

Science.gov (United States)

Lam, Hung; Kostov, Yordan; Rao, Govind; Tolosa, Leah

2009-12-01

In general, the most difficult task in developing devices for fluorescence ratiometric sensing is the isolation of signals from overlapping emission wavelengths. Wavelength discrimination can be achieved by using monochromators or bandpass filters, which often lead to decreased signal intensities. The result is a device that is both complex and expensive. Here we present an alternative system—a low-cost standalone optical fluorimeter based on luminescence lifetime assisted ratiometric sensing (LARS). This paper describes the principle of this technique and the overall design of the sensor device. The most significant innovation of LARS is the ability to discriminate between two overlapping luminescence signals based on differences in their luminescence decay rates. Thus, minimal filtering is required and the two signals can be isolated despite significant overlap of luminescence spectra. The result is a device that is both simple and inexpensive. The electronic circuit employs the lock-in amplification technique for the signal processing and the system is controlled by an onboard microcontroller. In addition, the system is designed to communicate with external devices via Bluetooth.

Influence of excitonic effects on luminescence quantum yield in silicon

Energy Technology Data Exchange (ETDEWEB)

Sachenko, A.V.; Kostylyov, V.P.; Vlasiuk, V.M. [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 prospect Nauky, 03028 Kyiv (Ukraine); Sokolovskyi, I.O., E-mail: isokolovskyi@mun.ca [V. Lashkaryov Institute of Semiconductor Physics, NAS of Ukraine, 41 prospect Nauky, 03028 Kyiv (Ukraine); Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, NL, A1B 3X7 Canada (Canada); Evstigneev, M. [Department of Physics and Physical Oceanography, Memorial University of Newfoundland, St. John' s, NL, A1B 3X7 Canada (Canada)

2017-03-15

Nonradiative exciton lifetime in silicon is determined by comparison of the experimental and theoretical curves of bulk minority charge carriers lifetime on doping and excitation levels. This value is used to analyze the influence of excitonic effects on internal luminescence quantum yield at room temperature, taking into account both nonradiative and radiative exciton lifetimes. A range of Shockley-Hall-Reed lifetimes is found, where excitonic effects lead to an increase of internal luminescence quantum yield.

Scintillation and optical stimulated luminescence of Ce-doped CaF2

International Nuclear Information System (INIS)

Yanagida, Takayuki; Fujimoto, Yutaka; Watanabe, Kenichi; Fukuda, Kentaro; Kawaguchi, Noriaki; Miyamoto, Yuka; Nanto, Hidehito

2014-01-01

Scintillation and optical stimulated luminescence of Ce 0.1–20% doped CaF 2 crystals prepared by Tokuyama Corp. were investigated. In X-ray induced scintillation spectra, luminescence due to Ce 3+ 5d–4f transition appeared around 320 nm with typically 40 ns decay time. By 241 Am 5.5 MeV α-ray irradiation, 0.1% doped one showed the highest scintillation light yield and the light yield monotonically decreased with Ce concentrations. Optically stimulated luminescence after X-ray irradiation was observed around 320 nm under 550 or 830 nm stimulation in all samples. As a result, intensities of optically stimulated luminescence were proportional to Ce concentrations. Consequently, scintillation and optically stimulated luminescence resulted to have a complementary relation in Ce-doped CaF 2 system. - Highlights: • Optical, scintillation, and OSL properties of Ce 0.1–20% doped CaF 2 were studied. • Scintillation light yield exhibited inverse proportionality to Ce concentrations. • OSL intensities showed proportionality to Ce concentrations. • Complementary relation of scintillation and OSL was experimentally confirmed

Luminescence in undoped CaYAl{sub 3}O{sub 7} produced via the Pechini method

Energy Technology Data Exchange (ETDEWEB)

Bispo, Giordano F.C., E-mail: gfredericoc@gmail.com [Physics Department, Federal University of Sergipe, 49100-000 São Cristovão, SE (Brazil); Andrade, Adriano B.; S Bezerra, Claudiane dos [Physics Department, Federal University of Sergipe, 49100-000 São Cristovão, SE (Brazil); Teixeira, Verônica C.; Galante, Douglas [Brazilian Synchrotron Light Laboratory, Brazilian Center for Research in Energy and Materials, 13083-970 Campinas, SP (Brazil); Valerio, Mário E.G. [Physics Department, Federal University of Sergipe, 49100-000 São Cristovão, SE (Brazil)

2017-02-15

The luminescent properties of CaYAl{sub 3}O{sub 7} (CYAM) were carried out in undoped powder samples produced via Pechini method. The thermal analysis combined with XRD measurements showed that 1000 °C/4 h is the best condition for the CYAM synthesis. Morphological analysis showed submicrometric particles with irregular shape. Photoluminescence (PL) emission and excitation spectra were studied with excitation in the ultraviolet and vacuum ultraviolet spectral region using synchrotron radiation. The CYAM band gap energy was measured and found to be around 6.8 eV. Low intense emission band around 4.4 eV, upon excitation at 6.5 eV, was assigned to the self-trapped excitons (STE) that are generated during the VUV excitation. Three main emission bands peaking at 2.57, 2.94 and 3.23 eV are responsible for most of the PL emission and radioluminescence (RL) emission in CYAM. Time-resolved measurements under pulsed 4.7 eV light showed that the PL decay curve is composed by 3 main processes with very short lifetime, smaller than 30 ns, and a small amount of long time constant process. Time-resolved RL measurements exciting with 4056 eV photons, above the Ca K edge, showed that the decay curve is composed by two processes with time constants around 27 and 130 ns and a small component due to a long decay constant bigger. All this features allowed the identification of the main emissions centres at 2.94 and 3.23 eV to the F{sup +} centres, while the emission centre at 2.57 eV is due to the F type centre.

Long-lived visible luminescence of UV LEDs and impact on LED excited time-resolved fluorescence applications

International Nuclear Information System (INIS)

Jin, D; Connally, R; Piper, J

2006-01-01

We report the results of a detailed study of the spectral and temporal properties of visible emission from three different GaN-based ultraviolet (UV) light emitting diodes (UV LEDs). The primary UV emission in the 360-380 nm band decays rapidly (less than 1 μs) following switch-off; however, visible luminescence (470-750 nm) with a decay lifetime of tens of microseconds was observed at approximately 10 -4 of the UV intensity. For applications of UV LEDs in time-resolved fluorescence (TRF) employing lanthanide chelates, the visible luminescence from the LEDs competes with the target Eu 3+ or Tb 3+ fluorescence in both spectral and temporal domains. A UV band-pass filter (Schott UG11 glass) was therefore used to reduce the visible luminescence of the UV LEDs by three orders of magnitude relative to UV output to yield a practical excitation source for TRF

Luminescence properties of the Sm-doped borate glasses

International Nuclear Information System (INIS)

Kindrat, I.I.; Padlyak, B.V.; Drzewiecki, A.

2015-01-01

The optical absorption and photoluminescence (emission and excitation) spectra as well as decay kinetics of a series of the Sm-doped glasses with Li 2 B 4 O 7 , LiKB 4 O 7 , CaB 4 O 7 , and LiCaBO 3 compositions were investigated and analysed. The Li 2 B 4 O 7 :Sm, LiKB 4 O 7 :Sm, CaB 4 O 7 :Sm, and LiCaBO 3 :Sm glasses of high optical quality have been obtained from the corresponding polycrystalline compounds in the air atmosphere, using a standard glass technology. On the basis of electron paramagnetic resonance (EPR) and optical spectra analysis it was shown that the samarium impurity is incorporated into the glass network as Sm 3+ (4f 5 , 6 H 5/2 ) ions, exclusively. All observed 4f – 4f transitions of the Sm 3+ centres in the optical absorption and luminescence spectra of the investigated glasses are identified. Most intense emission band of the Sm 3+ ions peaked about 598 nm ( 4 G 5/2 → 6 H 7/2 transition) is characterised by a single exponential decay with typical lifetime values, which depend on the basic glass composition as well as concentration and local structure of the Sm 3+ luminescence centres. The quantum efficiency has been evaluated for observed transitions of the Sm 3+ centres using obtained experimental lifetimes and radiative lifetimes calculated by Judd–Ofelt theory. The calculated high quantum efficiencies and measured quantum yields of luminescence show that the investigated borate glasses are perspective luminescence materials. Energy transfer from the Ce 3+ non-controlled impurity and intrinsic luminescence centres to the Sm 3+ centres has been observed. Peculiarities of the Sm 3+ local structure in the network of investigated glasses have been discussed based on the obtained spectroscopic results and structural data. - Highlights: • The Sm-doped Li 2 B 4 O 7 , LiKB 4 O 7 , CaB 4 O 7 , and LiCaBO 3 glasses of high quality were obtained. • EPR, optical absorption and luminescence spectra of Sm 3+ ions in obtained glasses were

Luminescence of CdSe/ZnS quantum dots infiltrated into an opal matrix

International Nuclear Information System (INIS)

Gruzintsev, A. N.; Emelchenko, G. A.; Masalov, V. M.; Yakimov, E. E.; Barthou, C.; Maitre, A.

2009-01-01

The effect of the photonic band gap in the photonic crystal, the synthesized SiO 2 opal with embedded CdSe/ZnS quantum dots, on its luminescence in the visible spectral region is studied. It is shown that the position of the photonic band gap in the luminescence and reflectance spectra for the infiltrated opal depends on the diameter of the constituent nanospheres and on the angle of recording the signal. The optimal conditions for embedding the CdSe/ZnS quantum dots from the solution into the opal matrix are determined. It is found that, for the opal-CdSe/ZnS nanocomposites, the emission intensity decreases and the luminescence decay time increases in the spatial directions, in which the spectral positions of the photonic band gap and the luminescence peak of the quantum dots coincide.

Effect of potential barrier growth of auto-localized excitons decay on radiation defects in AHC at low lattice symmetry

International Nuclear Information System (INIS)

Shunkeev, K.; Sagimbaeva, Sh.; Shunkeev, S.

2007-01-01

Effect of auto-localized excitons (ALE) luminescence strengthening is conditioned by two mechanisms: either decrease of potential barrier divided of quasi-free states and auto-localized states or decrease of emission-less channel effectiveness of exciton decay on primary radiation defects. In considered range (80 K) all excitons are only in auto-localized state. Therefore a realization of the first mechanism is improbable, For instant, in KI crystal at 80-100 K luminescence of free exciton is completely putting out, and ALE luminescence has maximal intensity. It is known that in the temperature range when ALE luminescence putting out is beginning an effectiveness of radiation defects is beginning to grow. This effect is related with predominating at that time emission-less exciton decay on radiation defects (F-H pairs). Experimentally by luminescence spectroscopy method activation energy of temperature putting out of ALE in AHC under uniaxial deformation. It is revealed, that increase of activation energy value has observed in a number of crystals: KBr→NaCl→KI→Na Br→CsBr→RbI. It is concluded, that effect of ALE intensity building-up and decrease of effectiveness of radiation defect formation are interpreted by growth of potential barrier of ALE decay into radiation defects under low symmetry of AHC lattice of low-temperature uniaxial deformation

Combustion synthesis and preliminary luminescence studies of ...

Indian Academy of Sciences (India)

The polycrystalline sample of LiBaPO4 : Tb3+ (LBPT) was successfully synthesized by solution combustion synthesis and studied for its luminescence characteristics. The thermoluminescence (TL) glow curve of LBPT material consists of two peaks at 204.54 and 251.21°C. The optimum concentration was 0.005 mol to ...

Structure, luminescence, and dynamics of Eu2O3 nanoparticles in MCM-41

International Nuclear Information System (INIS)

Chen, Wei; Joly, Alan G.; Kowalchuk, George A.; Malm, Jan-Olle; Huang, Yining; Bovin, Jan-Olov

2001-01-01

The structure, luminescence spectroscopy, and lifetime decay dynamics of Eu2O3 nanoparticles formed in MCM-41 have been investigated. Both X-ray diffraction and high resolution transmission electron microscope observations indicate that Eu2O3 nanoparticles of monoclinic structure are formed inside channels of MCM-41 by heating at 140 C. However, heat treatment at 600 and 700 C causes migration of Eu2O3 from the MCM-41 channels forming nanoparticles of cubic structure outside of the MCM-41 channels. The feature of the hypersensitive 5D0? 7F2 emission profile of Eu3+ is used to follow the structural changes. Photoluminescence lifetimes show the existence of short (< 1 microsecond) and long (microsecond to millisecond) components for each sample. The fast decay is attributed to quenching by surface states of the nanoparticles or energy transfer to the MCM-41 while the longer time decays show the effects of concentration quenching. The monoclinic sample prepared at 140 C shows a higher luminescence intensity than the cubic samples or the bulk powder

Synthesis and luminescence characteristics of Dy{sup 3+} doped KLa(PO{sub 3}){sub 4}

Energy Technology Data Exchange (ETDEWEB)

Chemingui, S.; Ferhi, M., E-mail: ferhi.mounir@gmail.com; Horchani-Naifer, K.; Férid, M.

2015-10-15

Polycrystalline powders of KLa{sub (1−x)}Dy{sub x}(PO{sub 3}){sub 4} (x=0.5%, 1%, 5% and 10%) with linear chain have been grown by solid state reaction. The obtained powders are characterized by X-ray powder diffraction, FTIR and Raman spectroscopies. Emission, excitation spectra and decay curves analysis have been used to study the spectroscopic properties of Dy{sup 3+} in KLa(PO{sub 3}){sub 4}. The photoluminescence spectra show two characteristic blue and yellow bands of Dy{sup 3+}. The yellow-to-blue emission intensity ratios and CIE chromaticity coordinates have been determined from emission spectra to evaluate the emitted light as function of Dy{sup 3+} concentration. The measured decay rates for {sup 4}F{sub 9/2}→{sup 6}H{sub 15/2} deviated from exponential to non-exponential shape with increase of Dy{sup 3+} concentration. The observed non-exponential behavior of the decay curve has been fitted to Inokuti–Hirayama model, which indicates that the energy transfer between the donor and the acceptor is of dipole–dipole nature. The energy transfer, between the donor (excited Dy{sup 3+}) and the acceptor (unexcited Dy{sup 3+}), increases with Dy{sup 3+} ions concentration. - Highlights: • Polycrystalline powders of KLa{sub (1−x)}Dy{sub x}(PO{sub 3}){sub 4} were grown by solid state reaction. • The obtained samples are characterized by XRD, FTIR and Raman spectroscopies. • The luminescent properties of Dy{sup 3+} in KLa(PO{sub 3}){sub 4} are investigated. • Lifetime and chromatic coordinates depend strongly on Dy{sup 3+} concentration. • White and blue emissions are obtained at high and low concentration, respectively.

Optimizing white light luminescence in Dy3+-doped Lu3Ga5O12 nano-garnets

International Nuclear Information System (INIS)

Haritha, P.; Linganna, K.; Venkatramu, V.; Martín, I. R.; Monteseguro, V.; Rodríguez-Mendoza, U. R.; Babu, P.; León-Luis, S. F.; Jayasankar, C. K.; Lavín, V.

2014-01-01

Trivalent dysprosium-doped Lu 3 Ga 5 O 12 nano-garnets have been prepared by sol-gel method and characterized by X-ray powder diffraction, high-resolution transmission electron microscopy, dynamic light scattering, and laser excited spectroscopy. Under a cw 457 nm laser excitation, the white luminescence properties of Lu 3 Ga 5 O 12 nano-garnets have been studied as a function of the optically active Dy 3+ ion concentration and at low temperature. Decay curves for the 4 F 9/2 level of Dy 3+ ion exhibit non-exponential nature for all the Dy 3+ concentrations, which have been well-fitted to a generalized energy transfer model for a quadrupole-quadrupole interaction between Dy 3+ ions without diffusion. From these data, a simple rate-equations model can be applied to predict that intense white luminescence could be obtained from 1.8 mol% Dy 3+ ions-doped nano-garnets, which is in good agreement with experimental results. Chromaticity color coordinates and correlated color temperatures have been determined as a function of temperature and are found to be within the white light region for all Dy 3+ concentrations. These results indicate that 2.0 mol% Dy 3+ ions doped nano-garnet could be useful for white light emitting device applications

A luminescence-optical spectroscopy study of Rb2KTiOF5 single crystals

Science.gov (United States)

Pustovarov, V. A.; Ogorodnikov, I. N.; Kozlov, A. V.; Isaenko, L. I.

2018-06-01

Large single crystals of Rb2KTiOF5 (RKTF), grown by slow solidification method, were studied (7-400 K) for various types of optical and radiation effects. The optical absorption spectra, the parameters of the Urbach rule at 293 K (σ = 0.24 and EU = 105 meV), the low-temperature reflection spectra (T = 7 K, E = 3.7-22 eV) were determined. The luminescence spectra (1.2-6.2 eV) and luminescence decay kinetics are studied upon excitation by a nanosecond electron beam (PCL), ultraviolet and vacuum ultraviolet light (PL), or X-rays radiation (XRL). PL excitation spectra under selective photoexcitation by synchrotron radiation (E = 3.7-22 eV, T = 7 K), temperature dependences of the intensity of steady-state XRL in different emission bands, as well as thermoluminescence (7-400 K) are studied. In the visible spectral region, we detected three luminescence bands that were attributed to radiative annihilation of intrinsic excitons (2.25 eV), recombination-type luminescence (2.1 eV) and luminescence of higher TiOF5 complexes (1.9 eV). The exponential component with lifetime of about 19 μs was revealed in the PCL decay kinetics at 2.25 eV. The low-energy onset of the intrinsic host absorption Ec = 3.55 eV was determined on the basis of the experimental data obtained. Spectra of optical constants were calculated by the Kramers-Krönig method, the energy of the onset of the interband transitions Eg = 4.2 eV was determined, and the main peaks of the optical spectra were identified.

Dynamics of Charged Excitons and Biexcitons in CsPbBr3 Perovskite Nanocrystals Revealed by Femtosecond Transient-Absorption and Single-Dot Luminescence Spectroscopy.

Science.gov (United States)

Yarita, Naoki; Tahara, Hirokazu; Ihara, Toshiyuki; Kawawaki, Tokuhisa; Sato, Ryota; Saruyama, Masaki; Teranishi, Toshiharu; Kanemitsu, Yoshihiko

2017-04-06

Metal-halide perovskite nanocrystals (NCs) are promising photonic materials for use in solar cells, light-emitting diodes, and lasers. The optoelectronic properties of these devices are determined by the excitons and exciton complexes confined in their NCs. In this study, we determined the relaxation dynamics of charged excitons and biexcitons in CsPbBr 3 NCs using femtosecond transient-absorption (TA), time-resolved photoluminescence (PL), and single-dot second-order photon correlation spectroscopy. Decay times of ∼40 and ∼200 ps were obtained from the TA and PL decay curves for biexcitons and charged excitons, respectively, in NCs with an average edge length of 7.7 nm. The existence of charged excitons even under weak photoexcitation was confirmed by the second-order photon correlation measurements. We found that charged excitons play a dominant role in luminescence processes of CsPbBr 3 NCs. Combining different spectroscopic techniques enabled us to clarify the dynamical behaviors of excitons, charged excitons, and biexcitons.

Luminescence properties of the Sm-doped borate glasses

Energy Technology Data Exchange (ETDEWEB)

Kindrat, I.I. [University of Zielona Góra, Institute of Physics, Division of Spectroscopy of Functional Materials, 4a Szafrana Street, 65-516 Zielona Góra (Poland); Padlyak, B.V., E-mail: B.Padlyak@if.uz.zgora.pl [University of Zielona Góra, Institute of Physics, Division of Spectroscopy of Functional Materials, 4a Szafrana Street, 65-516 Zielona Góra (Poland); Vlokh Institute of Physical Optics, 23 Dragomanov Street, 79-005 Lviv (Ukraine); Drzewiecki, A. [University of Zielona Góra, Institute of Physics, Division of Spectroscopy of Functional Materials, 4a Szafrana Street, 65-516 Zielona Góra (Poland)

2015-10-15

The optical absorption and photoluminescence (emission and excitation) spectra as well as decay kinetics of a series of the Sm-doped glasses with Li{sub 2}B{sub 4}O{sub 7}, LiKB{sub 4}O{sub 7}, CaB{sub 4}O{sub 7}, and LiCaBO{sub 3} compositions were investigated and analysed. The Li{sub 2}B{sub 4}O{sub 7}:Sm, LiKB{sub 4}O{sub 7}:Sm, CaB{sub 4}O{sub 7}:Sm, and LiCaBO{sub 3}:Sm glasses of high optical quality have been obtained from the corresponding polycrystalline compounds in the air atmosphere, using a standard glass technology. On the basis of electron paramagnetic resonance (EPR) and optical spectra analysis it was shown that the samarium impurity is incorporated into the glass network as Sm{sup 3+} (4f{sup 5}, {sup 6}H{sub 5/2}) ions, exclusively. All observed 4f – 4f transitions of the Sm{sup 3+} centres in the optical absorption and luminescence spectra of the investigated glasses are identified. Most intense emission band of the Sm{sup 3+} ions peaked about 598 nm ({sup 4}G{sub 5/2} → {sup 6}H{sub 7/2} transition) is characterised by a single exponential decay with typical lifetime values, which depend on the basic glass composition as well as concentration and local structure of the Sm{sup 3+} luminescence centres. The quantum efficiency has been evaluated for observed transitions of the Sm{sup 3+} centres using obtained experimental lifetimes and radiative lifetimes calculated by Judd–Ofelt theory. The calculated high quantum efficiencies and measured quantum yields of luminescence show that the investigated borate glasses are perspective luminescence materials. Energy transfer from the Ce{sup 3+} non-controlled impurity and intrinsic luminescence centres to the Sm{sup 3+} centres has been observed. Peculiarities of the Sm{sup 3+} local structure in the network of investigated glasses have been discussed based on the obtained spectroscopic results and structural data. - Highlights: • The Sm-doped Li{sub 2}B{sub 4}O{sub 7}, LiKB{sub 4}O{sub 7}, Ca

Luminescence thermometry with Eu{sup 3+} doped GdAlO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Lojpur, Vesna, E-mail: vesna.lojpur@yahoo.com; Ćulubrk, Sanja; Medić, Mina; Dramicanin, Miroslav

2016-02-15

Eu{sup 3+} doped GdAlO{sub 3} powder synthesized by solid state reaction was investigated for application in luminescence thermometry. Phase composition of material was confirmed by X-ray powder diffraction analysis. The photoluminescence emission spectra were collected under excitation of 399 nm, while elevating the temperature of the sample from the room temperature to 793 K. Emissions from {sup 5}D{sub 1}→{sup 7}F{sub 1} and {sup 5}D{sub 0}→{sup 7}F{sub 2} characteristic transitions of Eu{sup 3+} ions are selected for the temperature-dependence study using the fluorescence intensity ratio method. Emission decay curves measured at the strongest emission peak centered at 614 nm were recorded in a same temperature range. Data analysis showed that thermometry by fluorescence intensity ratio method can be used over the temperature region 293–793 K with the maximal relative sensitivity of 2.96% K{sup −1} (at 293 K). Temporal dependence of emission (lifetime) provides temperature sensing from 620 to 793 K with the maximal relative sensitivity of 2.28% K{sup −1}. - Highlights: • GdAlO{sub 3}: 4 at% of Eu{sup 3+} can be used for luminescence thermometry in the 293–793 K range. • Combined FIR and lifetime thermometry provide >0.5% K{sup −1} relative sensitivity. • Temperature dependence of lifetime is well described energy gap law model.

Luminescent decay and spectra of impurity-activated alkali halides under high pressure

International Nuclear Information System (INIS)

Klick, D.I.

1977-01-01

The effect of high pressure on the luminescence of alkali halides doped with the transition-metal ions Cu + and Ag + and the heavy-metal ions In + and Tl + was investigated to 140 kbar. Measurement of spectra allowed the prediction of kinetic properties, and the predictions agree with lifetime data

Determination of the kinetic parameters of BeO using isothermal decay method

International Nuclear Information System (INIS)

Nieto, Juan Azorin; Vega, Claudia Azorin; Montalvo, Teodoro Rivera; Cabrera, Eugenio Torijano

2016-01-01

Most of the existing methods for obtaining the frequency factors make use of the trap depth (activation energy) making some assumptions about the order of the kinetics. This causes inconsistencies in the reported values of trapping parameters due that the values of the activation energy obtained by different methods differ appreciably among them. Then, it is necessary to use a method independent of the trap depth making use of the isothermal luminescence decay (ILD) method. The trapping parameters associated with the prominent glow peak of BeO (280 °C) are reported using ILD method. As a check, the trap parameters are also calculated by glow curve shape (Chen's) method after isolating the prominent glow peak by thermal cleaning technique. Our results show a very good agreement between the trapping parameters calculated by the two methods. ILD method was used for determining the trapping parameters of BeO. Results obtained applying this method are in good agreement with those obtained using other methods, except in the value of the frequency factor. - Highlights: • Kinetic parameters of BeO were determined. • Isothermal decay method was used. • Frecuency factor not agree with those obtained by other methods.

An algorithm for unified analysis on the thermoluminescence glow curve

International Nuclear Information System (INIS)

Chung, K.S.; Park, C.Y.; Lee, J.I.; Kim, J.L.

2014-01-01

An algorithm was developed to integrally handle excitation by radiation, relaxation and luminescence by thermal or optical stimulation in thermoluminescence (TL) and optically stimulated luminescence (OSL) processes. This algorithm reflects the mutual interaction between traps through a conduction band. Electrons and holes are created by radiation in the beginning, and these electrons move to the trap through the conduction band. These holes move to the recombination center through a valence band. The ratio of the electrons allocated to each trap differs with the recombination probability and these values also relevant to the process of luminescence. Accordingly, the glow curve can be interpreted by taking the rate of electron–hole pairs created by ionizing radiation as a unique initial condition. This method differs from the conventional method of interpreting the measured glow curve with the initial electron concentration allocated to each trap at the end of irradiation. A program using the Visual Studio's C# subsystem was made to realize such a developed algorithm. To verify this algorithm it was applied to LiF:Mg,Cu,Si. The TL glow curve was deconvoluted with a model of five traps, one deep trap and one recombination center (RC). - Highlights: • TL glow curve deconvolution employing interacting model. • Simulation both irradiation and TL readout stages for various dose level. • Application in the identification TL kinetics of LiF:Mg,Cu,Si TLD

High-temperature peaks of thermostimulated luminescence in the ammonium halogens

International Nuclear Information System (INIS)

Kim, L.M.; Musenova, Eh.K.; Mukhamedrakhimov, K.U.

2003-01-01

The ammonium halogen crystals (AHC) are the close analogs of the alkali halogen crystals by the type of chemical bonds and crystal lattice structure. The ammonium halogen after irradiation by X-rays within 80-300 K range have two peaks of thermo-stimulation luminescence. Its maximums in dependence of anions type are in the 110-120 K and 170-180 K ranges. The first range is related with activation of auto-localized holes migration, and the second one - with the NH 3 + defects decay. Experimentally is established, that the pure ammonium halogens have memory about the previous irradiation at heating up to 300 K. After repeat irradiation the recombination luminescence high-temperature peak's shoulder is appearing. The second luminescence peak's shoulder revealing does not depend on the impurity center nature. It is known, that in the AHC there is the next thermo-stimulation luminescence peak within 340-360 K. The thermal annealing of this peak leads to the memory effect disappearance. So, the observing phenomenon is related with own defect of the matrix in the cation sublattice. Experimentally is established, that at a room temperature the AHC memorizing about previous irradiation during 20 h

Luminescence as a new detection method for non-relativistic highly ionizing particles in water/ice neutrino telescopes

Energy Technology Data Exchange (ETDEWEB)

Pollmann, Anna [Bergische Universitaet Wuppertal (Germany); Collaboration: IceCube-Collaboration

2016-07-01

Cosmic ray detectors use air as a radiator for luminescence. In water and ice detectors Cherenkov light is the dominant light producing mechanism when the particle velocity exceeds the Cherenkov threshold, approximately three quarters of the speed of light. Luminescence is produced by highly ionizing particles passing through matter due to the excitation of the surrounding atoms. The observables of luminescence, such as the wavelength spectrum and decay times, are highly dependent on the properties of the medium. Therefore, the results of measurements, in which luminescence was produced by particles passing through water or ice, vary by two orders of magnitude in intensity. It is shown that, even for the most conservative intensity value, luminescence can be used as a detection method for highly ionizing particles with velocities below the Cherenkov threshold. These could be magnetic monopoles or other massive and highly penetrating exotic particles. In the most optimistic case, luminescence contributes even to the light output of standard model particles.

Synthesis and luminescence properties of KMgF{sub 3}:Tm{sup 3+} fluoro perovskite

Energy Technology Data Exchange (ETDEWEB)

Perez C, L.; Cruz Z, E. [UNAM, Instituto de Ciencias Nucleares, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico); Marcazzo, J. [UNICEN, Instituto de Fisica Arroyo Seco, Gral. Pinto 399, B7000GHG Tandil (Argentina); Hernandez A, J. M.; Murrieta S, H., E-mail: ecruz@nucleares.unam.mx [UNAM, Instituto de Fisica, Circuito Exterior, Ciudad Universitaria, 04510 Mexico D. F. (Mexico)

2015-10-15

This paper presents the thermoluminescent (Tl) and radio luminescent (Rl) properties of the KMgF{sub 3} doped with Tm{sup 3+} ions at different concentration (0.05, 0.1, 0.2, 0.5 and 1.0 mol %). The KMgF{sub 3} binary compound was synthesized by solid state reaction. The characterization of the powder material was carried out by X-ray diffraction, scanning electron microscopy and by semiquantitative EDS analysis. The luminescence property of the powder and chips with Teflon samples was studied by thermoluminescence and radioluminescence phenomena. The Tl response as a function of the given dose was analyzed in the range between 0.5 Gy and 2500 Gy and a good linear response was obtained. Tl glow curves of KMgF{sub 3}:Tm show two overlapped peaks with maximums about 101, 146 degrees C and resolved peaks at 313 and 397 degrees C. The reproducibility of the Tl signal was tested and less than 5 % was obtained. The Tl signal decay was analyzed during a period of 33 days. Furthermore, the glow curve structure was studied by the thermal bleaching and the kinetics parameters values were obtained by a deconvolution process. On the other hand, the Rl response of different concentrations of thulium under beta irradiation was studied and the maximum of light output has been obtained for KMgF{sub 3} fluoro perovskite doped with 0.5 mol % of Tm{sup 3+} . The Rl spectrum showed the emission peaks at 455 and 360 nm, which can be ascribed to the {sup 1}D{sub 2}-{sup 3} F{sub 4} and {sup 1}D{sub 2}-{sup 3}H{sub 6} transitions of the Tm{sup 3+} ions. (Author)

Sensitivity equation for quantitative analysis with multivariate curve resolution-alternating least-squares: theoretical and experimental approach.

Science.gov (United States)

Bauza, María C; Ibañez, Gabriela A; Tauler, Romà; Olivieri, Alejandro C

2012-10-16

A new equation is derived for estimating the sensitivity when the multivariate curve resolution-alternating least-squares (MCR-ALS) method is applied to second-order multivariate calibration data. The validity of the expression is substantiated by extensive Monte Carlo noise addition simulations. The multivariate selectivity can be derived from the new sensitivity expression. Other important figures of merit, such as limit of detection, limit of quantitation, and concentration uncertainty of MCR-ALS quantitative estimations can be easily estimated from the proposed sensitivity expression and the instrumental noise. An experimental example involving the determination of an analyte in the presence of uncalibrated interfering agents is described in detail, involving second-order time-decaying sensitized lanthanide luminescence excitation spectra. The estimated figures of merit are reasonably correlated with the analytical features of the analyzed experimental system.

Preparation and determination of the luminescent characteristics of ZrO2 in powder

International Nuclear Information System (INIS)

Rivera M, T.; Olvera T, L.; Azorin N, J.; Soto E, A.M.; Velazquez O, C.; Campero C, A.

2004-01-01

In this work the luminescent characteristics of the ZrO 2 are presented using the method of Thermally Stimulated Luminescence (TSL), also called thermoluminescence (Tl). The powders of ZrO 2 were obtained by two preparation methods: for precipitation and for evaporation of Sol-gel. The luminescent characteristics of the ZrO 2 are determined using a lamp of radiation of UV light and a radiation source of beta particles of 90 Sr/ 90 Y. Using the method of thermal stimulation the curve representative thermoluminescent of the previously irradiated material was obtained. The curve Tl of the ZrO 2 irradiated with UV light presents a maximum in 180 C. Likewise, the spectrum of the curve Tl of the ZrO 2 irradiated with particles beta presents a maximum centered in 181 C. While using gamma radiation like excitement source one has a spectrum with a peak centered in 184 C. When subjecting the materials obtained by sol-gel to a process of calcination at 1000 C for 24 hours a curved Tl it presents with two maxim in 185 and in 290 C respectively. The intensity of the response induced in the material it is a decisive factor to continue studying the dosimetric characteristics of the ZrO 2 what allows to consider it as a potential material to use it in the beta particle dosimetry and of the UV light using the thermoluminescence method (Tl). (Author)

Influence of pre-measurement thermal treatment on OSL of synthetic quartz measured at room temperature

International Nuclear Information System (INIS)

Kale, Y.D.; Gandhi, Y.H.

2008-01-01

Much effort has been made to study the influence of pre-measurement thermal treatment and ionizing radiation on quartz specimens owing to its use in a large number of applications. Optically stimulated luminescence (OSL) being a structured and sensitive phenomenon promises to correlate the responsible color center and luminescence emission. OSL studies on quartz with such conditions can reveal many significant results. The aim of the present investigation is to understand the effect of annealing temperature on OSL characteristics of synthetic quartz recorded at room temperature. At identical annealing duration and β-dose, the shape of OSL decay curve remains non-exponential; when specimens annealed at lower temperature (∼400 deg. C). The shape of decay curve changes to exponential in nature along with rise in OSL intensity when the specimen was given higher temperature of annealing (>400 deg. C). The effects of such protocol on pattern of OSL sensitivity as well as area under the OSL decay curve are also presented here. The presence of shallow traps, when OSL decay curve was recorded at room temperature seems to be responsible for the changes in OSL pattern. The influence of shallow traps is attributed to non-exponential decay of OSL recorded at room temperature

Luminescence nanothermometry

Science.gov (United States)

Jaque, Daniel; Vetrone, Fiorenzo

2012-07-01

The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed.The current status of luminescence nanothermometry is reviewed in detail. Based on the main parameters of luminescence including intensity, bandwidth, bandshape, polarization, spectral shift and lifetime, we initially describe and compare the different classes of luminescence nanothermometry. Subsequently, the various luminescent materials used in each case are discussed and the mechanisms at the root of the luminescence thermal sensitivity are described. The most important results obtained in each case are summarized and the advantages and disadvantages of these approaches are discussed. This work was supported by the Universidad Autónoma de Madrid and Comunidad Autónoma de Madrid (Project S2009/MAT-1756), by the Spanish Ministerio de Educacion y Ciencia (MAT2010-16161) and by Caja Madrid Foundation.

Luminescence properties of a nanoporous freshwater diatom.

Science.gov (United States)

Goswami, Bondita; Choudhury, Amarjyoti; Buragohain, Alak K

2012-01-01

Freshwater diatom frustules show special optical properties. In this paper we observed luminescence properties of the freshwater diatom Cyclotella meneghiniana. To confirm the morphological properties we present scanning electron microscopy (SEM) images. X-ray diffraction (XRD) studies were carried out to visualize the structural properties of the frustules, confirming that silica present in diatom frustules crystallizes in an α-quartz structure. Study of the optical properties of the silica frustules of diatoms using ultra-violet-visible (UV-vis) spectroscopy and photoluminescence spectroscopy confirmed that the diatom C. meneghiniana shows luminescence in the blue region of the electromagnetic spectrum when irradiated with UV light. This property of diatoms can be exploited to obtain many applications in day-to-day life. Also, using time-resolved photoluminescence spectroscopy (TRPL) it was confirmed that this species of diatom shows bi-exponential decay. Copyright © 2011 John Wiley & Sons, Ltd.

New luminescence measurement facilities in retrospective dosimetry

DEFF Research Database (Denmark)

Lapp, Torben; Jain, Mayank; Thomsen, Kristina Jørkov

2012-01-01

), this facility has been used to measure natural doses in feldspar using the decaying NIR RL signal.Secondly, we present a method for mapping radiation field of the built-in 90Sr/90Y β-source and estimating grain-location specific dose-rates. This is important for the accuracy of single grain results, when......This paper gives a review of recent developments in luminescence measurement facilities on the Risø TL/OSL reader including radio-luminescence (RL), exo-electron and violet stimulation attachments, and a method for characterising and if necessary correcting for beta irradiation source non...... radiation field is spatially non-uniform across the sample area. We document the effect of this correction method and further investigate on the effect of lifting the source to achieve a better dose-rate uniformity.Finally we summarise two recently-developed novel facilities to help investigate (i) the time...

Synthesis of mixed ligand europium complexes: Verification of predicted luminescence intensification

International Nuclear Information System (INIS)

Lima, Nathalia B.D.; Silva, Anderson I.S.; Gonçalves, Simone M.C.; Simas, Alfredo M.

2016-01-01

Mixed ligand europium complexes are predicted to be more luminescent than what would be expected from their corresponding repeating ligand compounds according to a conjecture recently advanced by our research group; a conjecture that has already been validated for strongly luminescent europium complexes. In this article, we seek to further verify the validity of this conjecture for complexes which are much more symmetric, and which thus display lower levels of luminescence. Accordingly, we synthesized complexes Eu(DBM) 3 (L) 2 , and all novel mixed ligand combinations Eu(DBM) 3 (L,L') with L and L' equal to DBSO, PTSO, and TPPO. The syntheses were carried out via displacement reactions from the starting complex Eu(DBM) 3 (H 2 O) 2 , passing through the intermediates Eu(DBM) 3 (L) 2 and finally, by displacement of L by L', arriving at Eu(DBM) 3 (L,L'). The ligands L obey the following order of displacement TPPO>PTSO>DBSO>H 2 O, which had been previously described by our group. In the present article, we further show that this displacement order could have been predicted by Sparkle/RM1 thermochemical calculations. Subsequently, we determined the radiative decay rates, A rad , for all six compounds by photophysical measurements. As expected, results show that the measured A rad values for all novel mixed ligand complexes are larger than the average of the A rad values for the corresponding repeating ligand coordination compounds. In conclusion, the present article does broaden the scope of our conjecture, which enunciates that an increase in the diversity of ligands around the europium ion tends to intensify the luminescence. - Highlights: • Mixed ligand europium complexes are predicted to be more luminescent than repeating ligand ones. • Radiative decay rates increase with structural coordination asymmetry. • The non-ionic ligands displacement order in substitution reactions is TPPO>PTSO>DBSO>H 2 O. • Sparkle/RM1 correctly predicts the

Reduction of precursor decay anomaly in single crystal lithium fluoride

Science.gov (United States)

Sano, Yukio

2000-08-01

The purpose of this study is to reveal that the precursor decay anomaly in single crystal lithium fluoride is reduced by Sano's decay curve [Y. Sano, J. Appl. Phys. 85, 7616 (1999)], which is much smaller in slope than Asay's decay curve [J. R. Asay, G. R. Fowles, G. E. Duvall, M. H. Miles, and R. F. Tinder, J. Appl. Phys. 43, 2132 (1972)]. To this end, strain, particle, velocity, and stress in a precursor and near the leading edge of the follower changing with time along Sano's decay curve are first analyzed quantitatively. The analysis verified the existence of degenerate contraction waves I and II and a subrarefaction wave R', and the decay process [Y. Sano, J. Appl. Phys. 77, 3746 (1995)] caused in sequence by evolving followers C, I, II, R', Rb. Next, inequalities relating decay rates qualitatively to plastic strain rates at the leading edge of the follower, which are derived using the properties of the followers, are incorporated into the analysis. Calculation results showed that the plastic strain rates were reduced by low decay rates. This indicates that the precursor decay anomaly might be greatly reduced by Sano's decay curve.

Comparison of the luminescent properties of Lu3Al5O12:Pr crystals and films under synchrotron radiation excitation

International Nuclear Information System (INIS)

Zorenko, Yu.; Gorbenko, V.; Zorenko, T.; Voznyak, T.; Nizankovskiy, S.

2016-01-01

The work is dedicated to comparative investigation of the luminescent properties of Lu 3 Al 5 O 12 :Pr(LuAG:Pr) single crystals and single crystalline films using excitation by synchrotron radiation with an energy of 3.7–25 eV in the exciton range of LuAG host. We have found that the differences in the excitation spectra and luminescence decay kinetics of LuAG:Pr crystals and films are caused by involving the LuAl antisite defects and oxygen vacancies in the crystals and Pb 2+ flux related dopants in the films in the excitation processes of the Pr 3+ luminescence. Taking into account these differences, we have determined the energy structure of the Pr 3+ ions in LuAG host and estimated the differences in the energies of creation of excitons bound with the isolated Pr 3+ ions in LuAG:Pr films and the dipole Pr–LuAl antisite defect centers in the crystal counterpart. - Highlights: • Comparison of the luminescent properties of LuAG:Pr single crystals and films. • Superposition of the Pr 3+ and defect centers luminescence of LuAG:Pr crystal. • Different creation energies of an excitons bound with the Pr 3+ in LuAG:Pr crystals and films. • More faster decay kinetics of the Pr 3+ luminescence in LuAG:Pr films. • Low content of slow emission component in LuAG:Pr films.

submitter Preparation and luminescence properties of ZnO:Ga – polystyrene composite scintillator

CERN Document Server

Burešová, Hana; Turtos, Rosana Martinez; Jarý, Vítězslav; Mihóková, Eva; Beitlerová, Alena; Pjatkan, Radek; Gundacker, Stefan; Auffray, Etiennette; Lecoq, Paul; Nikl, Martin; Čuba, Václav

2016-01-01

Highly luminescent ZnO:Ga-polystyrene composite (ZnO:Ga-PS) with ultrafast subnanosecond decay was prepared by homogeneous embedding the ZnO:Ga scintillating powder into the scintillating organic matrix. The powder was prepared by photo-induced precipitation with subsequent calcination in air and Ar/H2 atmospheres. The composite was subsequently prepared by mixing the ZnO:Ga powder into the polystyrene (10 wt% fraction of ZnO:Ga) and press compacted to the 1 mm thick pellet. Luminescent spectral and kinetic characteristics of ZnO:Ga were preserved. Radioluminescence spectra corresponded purely to the ZnO:Ga scintillating phase and emission of polystyrene at 300-350 nm was absent. These features suggest the presence of non-radiative energy transfer from polystyrene host towards the ZnO:Ga scintillating phase which is confirmed by the measurement of X-ray excited scintillation decay with picosecond time resolution. It shows an ultrafast rise time below the time resolution of the experiment (18 ps) and a single-...

Luminescent properties and energy transfer of Gd{sup 3+}/Eu{sup 3+} co-doped cubic CaCO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Sun, Yidi; Zou, Haifeng; Zhang, Bowen; Zhou, Xiuqing; Song, Yanhua; Zheng, Keyan [College of Chemistry, Jilin University, Changchun 130012 (China); Shi, Zhan [State Key Laboratory of Inorganic Synthesis and Preparative Chemistry, College of Chemistry, Jilin University, Changchun 130012 (China); Sheng, Ye, E-mail: shengye@jlu.edu.cn [College of Chemistry, Jilin University, Changchun 130012 (China)

2016-10-15

Gd{sup 3+} and Eu{sup 3+} ions co-doped CaCO{sub 3} nanoparticles have been successfully synthesized via carbonization method. The emission spectra of co-doped CaCO{sub 3} phosphors in the range of VUV–vis spectral were studied. The results reveal that the co-doped CaCO{sub 3} phosphors show intense red emission in the VUV range because of the Gd{sup 3+} ions as sensitizers. The energy transfer process from Gd{sup 3+} to Eu{sup 3+} in CaCO{sub 3}:Gd{sup 3+}/Eu{sup 3+} phosphors was investigated and discussed in terms of the luminescence spectra and the decay curves, which demonstrated that the energy transfer of Gd{sup 3+}→Eu{sup 3+} is efficient. The mechanism of energy transfer from Gd{sup 3+} to Eu{sup 3+} is a resonant transfer, in which electric dipole–dipole interaction plays a leading role. Furthermore, the effect of doping concentration of Eu{sup 3+} ions on the energy transfer efficiency was also investigated. From the photoluminescence (PL) spectra, it was also found that the incorporation of Na{sup +} ions into CaCO{sub 3}:Gd{sup 3+}/Eu{sup 3+} could lead to a remarkable increase of luminescent intensity due to the charge compensation.

Radioactive decay of the late-time light curves of GRB-SNe

Science.gov (United States)

Misra, Kuntal; Fruchte, Andrew Steven

2018-04-01

We present the late-time Hubble Space Telescope observations of two GRB associated supernovae, GRB 030329/SN 2003dh and XRF 060218/SN 2006aj. Using the multi-color data upto ˜ 320 days after the burst, we constrain the late-time decay nature of these supernovae. The decay rates of SN 2003dh are steeper than SN 2006aj. A comparison with two other GRB supernovae, GRB 980425/SN 1998bw and the supernova associated with XRF 020903, shows that the decay rates of SN 2003dh are similar to XRF 020903 and those of SN 2006aj are similar to SN 1998bw. The late-time decay rates are steeper than the 56Co?56Fe radioactive decay rate (0.0098 mag day-1) indicating that there is some leakage of gamma-rays.

Preparation and photophysical properties of luminescent nanoparticles based on lanthanide doped fluorides (LaF3:Ce3+, Gd3+, Eu3+), obtained in the presence of different surfactants

International Nuclear Information System (INIS)

Runowski, Marcin; Lis, Stefan

2014-01-01

Highlights: • Synthesis of nanocrystalline lanthanide fluorides doped with Eu 3+ ions. • Inorganic nanomaterials exhibiting bright red luminescence. • Luminescence enhancement by energy transfer (ET) from Ce 3+ → Gd 3+ to Eu 3+ ions. • Decreased agglomeration and morphology control using organic modifiers/surfactants. • Absolute and relative quantum yield (QY) comparison. - Abstract: A series of nanomaterials composed of LaF 3 :Ce 3+ 10%, Gd 3+ 30%, Eu 3+ 1% was synthesized via a facile co-precipitation approach. The reaction between appropriate lanthanide (Ln 3+ ) and fluoride ions resulted in the formation of crystalline, Ln 3+ doped fluorides and was performed in the presence of a series of organic modifiers, acting as surfactants and anti-agglomeration agents. Modifiers such as polyacrylic acid (PAA), ethylenediaminetetraacetic acid (EDTA), citric acid and oleylamine most significantly influenced the morphology and spectroscopic properties of the products. The product obtained in the presence of PAA was composed of the smallest nanoparticles (ca. 5–6 nm), with narrow size/shape distribution. All fluorides synthesized exhibited intensive, bright red luminescence under UV irradiation (λ ex ≈ 250 nm), because of the presence of Eu 3+ ions in their structure. The efficient intensity of luminescence was a result of indirect excitation, via energy transfer (ET) phenomena occurring in the system (Ce 3+ → Gd 3+ → Eu 3+ ). The structure and morphology of the obtained nanomaterials were established by powder X-ray Diffraction (XRD) and Transmission Electron Microscopy (TEM) measurements. Optical properties of the obtained compounds were studied and discussed on the basis of excitation emission spectra and luminescence decay curves. On the basis of the performed measurements, luminescence quantum yield (absolute and relative) and radiative lifetimes were calculated and analyzed. FT-IR spectroscopy was applied to examine the presence of molecules of

Mechanism of luminescent emission in BaY2F8 scintillators doped with rare earths

International Nuclear Information System (INIS)

Santos, Ana Carolina de Mello

2013-01-01

In this work samples of Barium Yttrium Fluoride (BaY 2 F 8 -BaYF) doped with different concentrations of Tb 3+ , Er 3+ , Tm 3+ e Nd 3+ ions were characterized, aiming their application in radiation detection devices using their scintillating properties. Two types of samples were produced, polycrystalline samples, obtained via solid state reaction and single crystals, obtained via the floating zone melting method. The radioluminescence measurements (RL) revealed that the samples doped with 2.0 or 3.0 % Tb showed RL intensity at 545 nm two times higher than samples of CsI:Tl, although the total scintillation yield was smaller when compared to this commercial scintillator. Thermoluminescence (TL) results showed that all doped samples exhibited the same peak at 123°C, which is characteristic of the matrix (BaY 2 F 2 ). Comparison of the areas under the TL and RL curves for Tb 3+ and Nd 3+ doped BaYF revealed that the trapping centers are competing with the scintillation of the samples. However, this was not true for the Er 3+ and Tm 3+ doped samples and it was found that the scintillation yield is independent of the trap concentration up to a certain concentration limit. From this point on, the scintillation yields started increasing as the trap concentration increased. The radiation damage defects in BaYF:Tb 3+ were studied via optical absorption (OA) and correlated with TL, showing that trapping centers are connected to the color centers. All samples exhibited different luminescence decay processes with time constants ranging from microseconds, for the fast processes, milliseconds, for the intermediate ones, and phosphorescent processes with decay time on the order of seconds. For the Nd 3+ doped samples, very fast decay process was also found with time constants of about 60ns and that is an indication that this material can be used in fast detection systems, although its scintillation efficiency was weak. The combined results obtained with these techniques together

Mathematical aspects of ground state tunneling models in luminescence materials

International Nuclear Information System (INIS)

Pagonis, Vasilis; Kitis, George

2015-01-01

Luminescence signals from a variety of natural materials have been known to decrease with storage time at room temperature due to quantum tunneling, a phenomenon known as anomalous fading. This paper is a study of several mathematical aspects of two previously published luminescence models which describe tunneling phenomena from the ground state of a donor–acceptor system. It is shown that both models are described by the same type of integral equation, and two new analytical equations are presented. The first new analytical equation describes the effect of anomalous fading on the dose response curves (DRCs) of naturally irradiated samples. The DRCs in the model were previously expressed in the form of integral equations requiring numerical integration, while the new analytical equation can be used immediately as a tool for analyzing experimental data. The second analytical equation presented in this paper describes the anomalous fading rate (g-Value per decade) as a function of the charge density in the model. This new analytical expression for the g-Value is tested using experimental anomalous fading data for several apatite crystals which exhibit high rate of anomalous fading. The two new analytical results can be useful tools for analyzing anomalous fading data from luminescence materials. In addition to the two new analytical equations, an explanation is provided for the numerical value of a constant previously introduced in the models. - Highlights: • Comparative study of two luminescence models for feldspars. • Two new analytical equations for dose response curves and anomalous fading rate. • The numerical value z=1.8 of previously introduced constant in models explained.

Luminescence of La3+ and Sc3+ impurity centers in YAlO3 single-crystalline films

International Nuclear Information System (INIS)

Zorenko, Yu.; Gorbenko, V.; Voznyak, T.; Zorenko, T.; Nikl, M.; Nejezchleb, K.

2008-01-01

The luminescence of La Y 3+ and Sc Y 3+ and Sc Al 3+ centers created by lanthanum and scandium ions at Y 3+ and Al 3+ cation sites of YAlO 3 perovskite lattice was investigated. The features of emission of excitons localized at the mentioned centers in YAlO 3 :La and YAlO 3 :Sc single-crystalline films were analyzed by means of time-resolved emission spectroscopy and luminescence decay kinetics measurements under excitation by synchrotron radiation at 9 and 300 K

Color-tunable up-conversion emission of luminescent-plasmonic, core/shell nanomaterials – KY{sub 3}F{sub 10}:Yb{sup 3+},Tm{sup 3+}/SiO{sub 2}-NH{sub 2}/Au

Energy Technology Data Exchange (ETDEWEB)

Runowski, Marcin, E-mail: runowski@amu.edu.pl

2017-06-15

Multifunctional luminescent-plasmonic KY{sub 3}F{sub 10}:Yb{sup 3+},Tm{sup 3+}/SiO{sub 2}-NH{sub 2}/Au nanomaterials were successfully obtained. The lanthanide-doped fluoride nanoparticles (NPs), synthesized under hydrothermal conditions exhibited bright blue up-conversion luminescence (λ{sub ex}=980 nm). Such lanthanide nanocrystals (20–40 nm) were coated with amine modified silica shell, forming core/shell nanostructures. Their surface was further uniformly covered with ultra-small gold NPs (4–7 nm). The as-prepared luminescent-plasmonic core/shell nanomaterials exhibited tunable up-conversion emission, due to the interactions between plasmonic and luminescent phases. The emission of Tm{sup 3+} ion was affected by the surface Au NPs, which exhibited strong plasmonic absorption in the visible range (450–650 nm). The increasing amount of the surface Au NPs, led to the significant alterations in a ratio of the Tm{sup 3+} emission bands. The NIR band ({sup 3}H{sub 4}→{sup 3}H{sub 6}) was unchanged, whereas the ratio and relative intensity of the bands in a visible range ({sup 1}G{sub 4}→{sup 3}H{sub 6} and {sup 1}G{sub 4}→{sup 3}F{sub 4}) was altered. This led to the significant change of the emission spectra shape and influenced color of emission, tuning it from bright blue to blue-violet. The products obtained were characterized by transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), powder X-ray diffraction (XRD), UV–vis absorption spectroscopy and luminescence spectroscopy (excitation/emission spectra and luminescence decay curves).

Synthesis and spectroscopic behavior of highly luminescent trinuclear europium complexes with tris-β-diketone ligand

Energy Technology Data Exchange (ETDEWEB)

Wang, Dunjia, E-mail: dunjiawang@163.com; Pi, Yan; Liu, Hua; Wei, Xianhong; Hu, Yanjun; Zheng, Jing

2014-11-15

Highlights: • Synthesis of the tris-β-diketone ligand and its trinuclear europium complexes. • Photoluminescence behavior of trinuclear europium complexes. • Analysis of the Judd–Ofelt intensity parameters (Ω{sub t}), lifetime (τ) and quantum yield (η). - Abstract: A new tris-β-diketone ligand, 2-[4,6-bis-(1-benzoyl-2-oxo-2-phenyl-ethyl)-[1,3,5]triazin-2-yl] -1,3-diphenyl-propane-1,3-dione (H{sub 3}L), and its trinuclear europium complexes, Eu{sub 3}(DBM){sub 6}L (C1), Eu{sub 3}(DBM){sub 6}(Bipy){sub 3}L (C2) and Eu{sub 3}(DBM){sub 6}(Phen){sub 3}L (C3) were synthesized and their spectroscopic behaviors were studied by FT-IR, {sup 1}H NMR, UV–vis and photoluminescence spectroscopic techniques. These europium complexes exhibited the characteristic emission bands that arise from the {sup 5}D{sub 0} → {sup 7}F{sub J} (J = 0–4) transitions of the europium ion in solid state. The Ω{sub 2} and Ω{sub 4} intensity parameters, lifetime (τ) and luminescence quantum yield (η) were calculated according to the emission spectra and luminescence decay curves in solid state. The results indicated that these trinuclear europium complexes displayed a longer lifetime (τ) and higher luminescence quantum efficiency (η), especially complexes C2 (τ = 0.820 ms, η = 46.5%) and C3 (τ = 0.804 ms, η = 47.4%), which due to the effect of two additional europium ion lumophors and the introduction of the third ligands, Bipy or Phen in trinuclear complexes. Their Ω{sub 2} values demonstrated that the europium ion in these complexes is in a highly polarizable chemical environment.

SPORT: A new sub-nanosecond time-resolved instrument to study swift heavy ion-beam induced luminescence - Application to luminescence degradation of a fast plastic scintillator

Science.gov (United States)

Gardés, E.; Balanzat, E.; Ban-d'Etat, B.; Cassimi, A.; Durantel, F.; Grygiel, C.; Madi, T.; Monnet, I.; Ramillon, J.-M.; Ropars, F.; Lebius, H.

2013-02-01

We developed a new sub-nanosecond time-resolved instrument to study the dynamics of UV-visible luminescence under high stopping power heavy ion irradiation. We applied our instrument, called SPORT, on a fast plastic scintillator (BC-400) irradiated with 27-MeV Ar ions having high mean electronic stopping power of 2.6 MeV/μm. As a consequence of increasing permanent radiation damages with increasing ion fluence, our investigations reveal a degradation of scintillation intensity together with, thanks to the time-resolved measurement, a decrease in the decay constant of the scintillator. This combination indicates that luminescence degradation processes by both dynamic and static quenching, the latter mechanism being predominant. Under such high density excitation, the scintillation deterioration of BC-400 is significantly enhanced compared to that observed in previous investigations, mainly performed using light ions. The observed non-linear behaviour implies that the dose at which luminescence starts deteriorating is not independent on particles' stopping power, thus illustrating that the radiation hardness of plastic scintillators can be strongly weakened under high excitation density in heavy ion environments.

Spectroscopic properties of chromium(III) in zirconium barium fluoride glass (ZBLA)

International Nuclear Information System (INIS)

Balda, R.; Fernandez, J.; Illarramendi, M.A.; Elejalde, M.J.

1988-01-01

The optical properties of trivalent chromium ions in ZBLA glass have been studied for different concentrations of Cr 3 + . Optical absorption, luminescence and lifetimes have been investigated in a wide range of temperatures. The relative quantum efficiencies of these systems have been determined from the integrated luminescence decay curves as a function of the excitation wavelength

Laboratory fading rates of various luminescence signals from feldspar-rich sediment extracts

DEFF Research Database (Denmark)

Thomsen, Kristina Jørkov; Murray, A.S.; Jain, Mayank

2008-01-01

Feldspar as a retrospective dosimeter is receiving more and more attention because of its useful luminescence properties; in particular the dose response curve extends to significantly higher doses than quartz. However, feldspars have one major disadvantage; both the thermoluminescence (TL...

Synthesis and luminescence properties of KSrPO{sub 4}:Eu{sup 2+} phosphor for radiation dosimetry

Energy Technology Data Exchange (ETDEWEB)

Palan, C. B., E-mail: chetanpalan27@yahoo.in [Department of Physics, Sant Gadge Baba Amravati University, Amravati-444602 (India); Bajaj, N. S. [Toshniwal ACS College, Sengaon, Hingoli-431542 (India); Omanwar, S. K.

2016-05-06

The KSrPO{sub 4}:Eu phosphor was synthesized via solid state method. The structural and morphological characterizations were done through XRD (X-ray diffraction) and SEM (Scanning Electronic Microscope). Additionally, the photoluminescence (PL), thermoluminescence (TL) and optically Stimulated luminescence (OSL) properties of powder KSrPO{sub 4}:Eu were studied. The PL spectra show blue emission under near UV excitation. It was advocated that KSrPO{sub 4}:Eu phosphor not only show OSL sensitivity (0.47 times) but also gives faster decay in OSL signals than that of Al{sub 2}O{sub 3}:C (BARC) phosphor. The TL glow curve consist of two shoulder peaks and the kinetics parameters such as activation energy and frequency factors were determined by using peak shape method and also photoionization cross-sections of prepared phosphor was calculated. The radiation dosimetry properties such as minimum detectable dose (MDD), dose response and reusability were reported.

On the half-life of luminescence signals in dosimetric applications: A unified presentation

Science.gov (United States)

Pagonis, V.; Kitis, G.; Polymeris, G. S.

2018-06-01

Luminescence signals from natural and man-made materials are widely used in dosimetric and dating applications. In general, there are two types of half-lives of luminescence signals which are of importance to experimental and modeling work in this research area. The first type of half-life is the time required for the population of the trapped charge in a single trap to decay to half its initial value. The second type of half-life is the time required for the luminescence intensity to drop to half of its initial value. While there a handful of analytical expressions available in the literature for the first type of half-life, there are no corresponding analytical expressions for the second type. In this work new analytical expressions are derived for the half-life of luminescence signals during continuous wave optical stimulation luminescence (CW-OSL) or isothermal luminescence (ITL) experiments. The analytical expressions are derived for several commonly used luminescence models which are based on delocalized transitions involving the conduction band: first and second order kinetics, empirical general order kinetics (GOK), mixed order kinetics (MOK) and the one-trap one-recombination center (OTOR) model. In addition, half-life expressions are derived for a different type of luminescence model, which is based on localized transitions in a random distribution of charges. The new half-life expressions contain two parts. The first part is inversely proportional to the thermal or optical excitation rate, and depends on the experimental conditions and on the cross section of the relevant luminescence process. The second part is characteristic of the optical and/or thermal properties of the material, as expressed by the parameters in the model. A new simple and quick method for analyzing luminescence signals is developed, and examples are given of applying the new method to a variety of dosimetric materials. The new test allows quick determination of whether a set of

Co-doping effects on luminescence and scintillation properties of Ce doped Lu3Al5O12 scintillator

International Nuclear Information System (INIS)

Kamada, Kei; Nikl, Martin; Kurosawa, Shunsuke; Beitlerova, Alena; Nagura, Aya; Shoji, Yasuhiro; Pejchal, Jan; Ohashi, Yuji; Yokota, Yuui; Yoshikawa, Akira

2015-01-01

The Mg, Ca, Sr and Ba 200 ppm co-doped Ce:Lu 3 Al 5 O 12 single crystals were prepared by micro pulling down method. Absorption and luminescence spectra were measured together with several other scintillation characteristics, namely the scintillation decay and light yield to reveal the effect of the co-doping. The scintillation decays were accelerated by both Mg and Ca co-dopants. The Mg co-doped samples showed the fastest decay and the highest light yield among the co-doped samples

Correlated decay curve measurement of the lifetime of the 4p2sup(p)sup(o) term in Ge IV

International Nuclear Information System (INIS)

Pinnington, E.H.; Bahr, J.L.; Irwin, D.J.G.

1981-01-01

An ANDC analysis of beam-foil decay curves for the 4s-4p, 4p-4d and 4p-5s transitions in Ge IV yield 4p lifetimes 0.91 +- 0.05 ns (j = 1/2) and 0.82 +- 0.05 ns (j = 3/2) and hence a 4s-4p multiplet f value of 0.77 +- 0.05, in excellent agreement with MCHF and RHF (+core polarization) calculations. (orig.)

Long lasting yellow phosphorescence and photostimulated luminescence in Sr3SiO5 : Eu2+ and Sr3SiO5 : Eu2+, Dy3+ phosphors

International Nuclear Information System (INIS)

Sun Xiaoyuan; Zhang Jiahua; Zhang Xia; Luo Yongshi; Wang Xiaojun

2008-01-01

We report the observation of long lasting yellow phosphorescence and photostimulated luminescence (PSL) in Sr 3 SiO 5 : Eu 2+ and Sr 3 SiO 5 : Eu 2+ , Dy 3+ phosphors. The decay patterns of phosphorescence and thermoluminescence curves demonstrate that introduction of Dy 3+ into Sr 3 SiO 5 : Eu 2+ can generate a large number of shallow traps and deep traps. The generated deep traps prolong the phosphorescence up to 6 h after UV irradiation. The PSL is studied under 808 nm excitation. Slow rising and falling edges of the emission in Sr 3 SiO 5 : Eu 2+ , Dy 3+ are observed, showing a retrapping process by the generated shallow traps due to co-doping Dy 3+ .

Luminescence and scintillation of Ce.sup.3+./sup.- doped high silica glass

Czech Academy of Sciences Publication Activity Database

Chewpraditkul, W.; Shen, Y.; Chen, D.; Yu, B.; Průša, Petr; Nikl, Martin; Beitlerová, Alena; Wanarak, C.

2012-01-01

Roč. 34, č. 11 (2012), s. 1762-1766 ISSN 0925-3467 R&D Projects: GA MŠk LH12185 Institutional research plan: CEZ:AV0Z10100521 Keywords : Ce 3+ * luminescence * porous materials * scintillation * photoluminescence decay Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.918, year: 2012 http://dx.doi.org/10.1016/j.optmat.2012.04.012

On the role of non-bridging oxygen centers in the red luminescence emission from silicon nanocrystals

Energy Technology Data Exchange (ETDEWEB)

Borsella, Elisabetta; D' Amato, Rosaria; Fabbri, Fabio [ENEA, C. R. Frascati, via E. Fermi 45, 00044 Frascati, Roma (Italy); Falconieri, Mauro [ENEA, C. R. Casaccia, via Anguillarese 301, 00123 Roma (Italy); Trave, Enrico [Physical Chemistry Department, Universita Ca' Foscari Venezia, Dorsoduro 2137, 30123 Venezia (Italy); Bello, Valentina; Mattei, Giovanni [Physics Department, Universita degli Studi di Padova, Via Marzolo 8, 35131 Padova (Italy); Nie, Yaru; Wang, Dayang [Max Planck Institute of Colloids and Interfaces, 14424 Potsdam (Germany)

2011-03-15

The process responsible for visible-near infrared luminescence emission in Si nanostructures has been generating significant controversy for years. The debate has focused on whether light emission is originated by recombination of quantum confined excitons or by defects located at the surface. It is experimentally difficult to distinguish the two contributions since both are size-dependent. Moreover, all the studies were performed on different systems and consequently the comparisons were not free from ambiguities. Here we relate the spectroscopic properties of pyrolytic Si nanocrystals, aged in air, and after complete conversion to amorphous silica by alkali etching-assisted oxidation. The strong resemblance of the spectral and time decay behavior of the red PL emission in both systems (surface oxidized nanocrystalline Si and amorphous silica sample) indicates that this emission is dominated by defects in the silicon oxide. The strongly non-exponential time behavior of the photo-luminescence emission in both systems can be modeled as the sum of exponential decays from the emitting defects, thus ruling out the interpretation in terms of the so-called ''stretched exponential'' decay. Using this model we also obtained the emission energy and inhomogeneous linewidth of the luminescent defects, allowing us to identify them as the non-bridging oxygen hole centers. The emission energy of these defects depends strongly on their physical and chemical environment and can produce a shift apparently due to the size effect. (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Growth and luminescent properties of the Ce, Pr doped NaCl single crystals grown by the modified micro-pulling-down method

International Nuclear Information System (INIS)

Yokota, Yuui; Yanagida, Takayuki; Fujimoto, Yutaka; Nikl, Martin; Yoshikawa, Akira

2010-01-01

We have investigated luminescent properties of nondope, Ce and Pr doped NaCl [nondope NaCl, Ce:NaCl, Pr:NaCl] single crystals grown by a modified micro-pulling-down method with a removable chamber system. Nondope, Ce 1% and Pr 1% doped NaCl crystals with a single phase of NaCl structure were obtained and the crystals indicated general crystal quality by the X-ray rocking curve measurement. For the nondope NaCl and Pr:NaCl crystals, the transmittance spectra indicated almost more than 60% in the wavelength from 200 to 800 nm and an absorption of Ce 3+ ion was observed in the transmittance spectrum of Ce:NaCl crystal. The emission spectrum originated from Ce 3+ 5d-4f transition appeared around 300 nm in the photoluminescence spectrum and the decay time was 19.7 ns.

Further investigations into the luminescence of silver-activated ZnS:CdS phosphors containing nickel and cobalt

International Nuclear Information System (INIS)

Elmanharawy, M.S.; Eid, A.H.

1978-01-01

An attempt has been made to explain the luminescence of (ZnS : CdS : Ag : Ni : Co) phosphors using the uniform luminescence centre model of zinc sulphide. The phosphors investigated give rise to characteristic glow curves with a number of peaks depending on the cobalt content. The emitted thermoluminescence consists of two bands: a yellow band at 5900 A and another in the red region of the spectrum (7000 A). These peak wavelengths coincide reasonably well with values of 5800 A and 6800 A predicted by the uniform luminescence centre model. It is suggested that the yellow terhmoluminescence takes place with the participation of the conduction band while electron transfer via the conduction band from traps to separated luminescence centres is assumed for the red glow. (author)

Luminescence properties of In(Zn)P alloy core/ZnS shell quantum dots

Science.gov (United States)

Thuy, Ung Thi Dieu; Reiss, Peter; Liem, Nguyen Quang

2010-11-01

Chemically synthesized InP/ZnS core/shell quantum dots (QDs) are studied using time-resolved photoluminescence spectroscopy and x-ray diffraction. Zinc stearate, which is added during the synthesis of the InP core, significantly improves the optical characteristics of the QDs. The luminescence quantum yield (QY) reaches 60%-70% and the emission is tunable from 485 to 586 nm by varying the Zn2+:In3+ molar ratio and growth temperature. The observed increased Stokes shift, luminescence decay time, and QY in the presence of Zn are rationalized by the formation of an In(Zn)P alloy structure that causes band-edge fluctuation to enhance the confinement of the excited carriers.

Thermal and electron stimulated luminescence of natural bones, commercial hydroxyapatite and collagen.

Science.gov (United States)

Roman-Lopez, J; Correcher, V; Garcia-Guinea, J; Rivera, T; Lozano, I B

2014-01-01

The luminescence (cathodoluminescence and thermoluminescence) properties of natural bones (Siberian mammoth and adult elephant), commercial hydroxyapatite and collagen were analyzed. Chemical analyses of the natural bones were determined using by Electron Probe Micro-Analysis (EMPA). Structural, molecular and thermal characteristics were determined by X-ray Diffraction (XRD), Raman spectroscopy and Differential Thermal and Thermogravimetric analysis (DTA-TG). Cathodoluminescence (CL) spectra of natural bones and collagen showed similar intense broad bands at 440 and 490 nm related to luminescence of the tetrahedral anion [Formula: see text] or structural defects. A weaker luminescence exhibited at 310 nm could be attributed to small amount of rare earth elements (REEs). Four luminescent bands at 378, 424, 468 and 576 nm were observed in the commercial hydroxyapatite (HAP). Both natural bones and collagen samples exhibited natural thermoluminescence (NTL) with well-defined glow curves whereas that the induced thermoluminescence (ITL) only appears in the samples of commercial hydroxyapatite and collagen. Additional explanations for the TL anomalous fading of apatite, as a crucial difficulty performing dosimetry and dating, are also considered. Copyright © 2013 Elsevier B.V. All rights reserved.

Characterization and luminescent properties of thermally annealed olivines

International Nuclear Information System (INIS)

Colin-Garcia, Maria; Correcher, Virgilio; Garcia-Guinea, Javier; Heredia-Barbero, Alejandro; Roman-Lopez, Jesus; Ortega-Gutierrez, Fernando; Negron-Mendoza, Alicia; Ramos-Bernal, Sergio

2013-01-01

Olivine is an iron-magnesium solid solution silicate (Mg,Fe) 2 SiO 4 and it is probably one of the most abundant mineral phase in the Solar System, it is present in the primitive carbonaceous meteorites (i.e Allende), and in ordinary chondritic meteorite, comets or terrestrial planets. The olivine grains in those bodies have been exposed to different radiation sources like UV, electrons, cosmic radiation, etc. Here, we explore the effect of ionizing and non ionizing radiation on the luminescence emission of the two well-characterised olivine samples from Mexico and Spain by means of cathodoluminescence and thermoluminescence. The analyses by X-ray dispersive energies in the scanning electron microscopy show differences between the samples in the amount of iron and magnesium and also show traces of rare elements. Olivine exhibits spectral cathodoluminescence emissions of low intensity, explained for the quenching of the luminescence of the iron, and sharp signals assigned as impurities. Cathodoluminescence and thermoluminescence glow curves of the natural, and UV induced olivine samples were obtained. Our results show that thermal treatments at 1100 °C change the mineral molecular structure and the luminescence properties of this mineral phase. These results confirm an active participation of physical factors influencing the luminescent properties of olivine. -- Highlights: ► Luminescent properties of two olivines samples (Mexican and Spanish) were explored. ► EDS show different iron and magnesium content and traces of rare elements on both. ► Olivine exhibits spectral CL emissions of low intensity due to the quenching of iron. ► Treatments at 1100 °C change the mineral structure and its response to UV radiation

Luminescence dating

International Nuclear Information System (INIS)

Rieser, U.

2013-01-01

The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materials in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs.

Luminescence dating

International Nuclear Information System (INIS)

Rieser, U.

2009-01-01

The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materals in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs.

Luminescence dating

International Nuclear Information System (INIS)

Rieser, U.

2008-01-01

The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materals in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs

Luminescence dating

International Nuclear Information System (INIS)

Rieser, U.

2012-01-01

The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materials in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs.

Luminescence dating

International Nuclear Information System (INIS)

Rieser, U.

2009-01-01

The luminescence techniques have evolved over the last 40 years to a powerful dating instrument in archaeology and geoscience. Depending on how the luminescence is stimulated, one distinguishes the phenomena of thermoluminescence (TL), optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL). Each of these phenomena has its specific potential for dating various archaeological materals in the time range from medieval back to palaeolithic periods, or, speaking in geological terms, for dating of Holocene and late Pleistocene objects. The OSL and IRSL techniques are sometimes treated together as 'optical dating'. The luminescence techniques differ from other major dating techniques, such as 14 C, essentially by their applicability to inorganic materials, their wide age-range from about 100 years to more than 100,000 years and the kind of datable events which are the last exposure to heat or to light. (author). 10 refs., 3 figs

Ab initio calculations of cross luminescence materials

International Nuclear Information System (INIS)

Kanchana, V.

2016-01-01

Abintio calculations have been performed to study the structural, electronic, and optical properties of ABX 3 (A=alkali, B=alkaline-earth, and X=halide) compounds. The ground state properties are calculated using the pseudopotential method with the inclusion of van der Waals interaction, which we find inevitable in reproducing the experimental structure properties in alkali iodides because of its layered structure. All calculations were performed using the Full-Potential Linearized Augmented Plane Wave method. The band structures are plotted with various functionals and we find the newly developed Tran and Blaha modified Becke-Johnson potential to improve the band gap significantly. The optical properties such as complex dielectric function, refractive index, and absorption spectra are calculated which clearly reveal the optically isotropic nature of these materials though being structurally anisotropic, which is the key requirement for ceramic scintillators. Cross luminescence materials are very interesting because of its fast decay. One of the major criteria for the cross luminescence to happen is the energy difference between valence band and next deeper core valence band being lesser when compared to energy gap of the compound, so that radiative electronic transition may occur between valence band and core valence band. We found this criteria to be satisfied in all the studied compounds leading to cross luminescence except for KSrI 3 , RbSrI 3 . The present study suggest that among the six compounds studied, CsSrI 3 , CsMgCl 3 , CsCaCl 3 , and CsSrCl 3 compounds are cross luminescence materials, which is well explained from the band structure, optical properties calculations. Chlorides are better scintillators that iodides and CsMgCl 3 is found to be promising one among the studied compounds. Apart from these materials we have also discussed electronic structure and optical properties of other scintillator compounds. (author)

Process for producing a self luminescent material

Energy Technology Data Exchange (ETDEWEB)

Abe, E

1962-01-28

A self luminescent material is produced by a process comprising applying a hydroxide or fluoride of promethium-147 suspended in a medium of paraffinic acid to the surface of a fluorescent body. Promethium-147 decays with a half-life of 2.6 years and emits beta-rays but not alpha- and gamma-rays so that it is suitable for manufacturing self luminescent materials. A chloride of promethium-147 cannot be employed because its structure is destroyed by acids. Although fluorides and hydroxides of promethium-147 are difficult to mix with the fluorescent body material, they become mixable when paraffinic acids containing from 12 to 20 carbon atoms, (for example, steric acid, palmitic acid and margaric acid) are used as a medium. In embodiments, the self luminescent materials are prepared by either neutralization of a promethium-147 chloride solution having a specific radioactivity of 1.2 c/cc. with an ammonium hydroxide solution to form gelatinous hydroxide, or the reaction of a promethium-147 chloride solution with H/sub 2/SiF/sub 6/ by heating at 80/sup 0/C to form a fluoride of promethium-147. The products have a specific radioactivity of 8 to 12 mc/g. These products are suspended in vehicles of polystyrene and methacrylic resin to produce the self luminescent coating materials. Tests show that the initical brightness is comparatively high, the decreasing rate of brightness is small, no blackening effects by alpha-rays occur and costs are low. The brightness of the coating containing promethium-147 is 82-85 after 5 days, 100-105 after 100 days and 82-92 after 180 days. With respect to the coating containing radium the values are 31-70 after 5 days, 28-49 after 100 days and 19-31 after 180 days.

Dependence of cross-relaxation on temperature and concentration from the 1D2 level of Pr3+ in YPO4

International Nuclear Information System (INIS)

Collins, John; Geen, Megan; Bettinelli, M.; Di Bartolo, B.

2012-01-01

We report on the role of cross-relaxation in the decay of the 1 D 2 level of trivalent Pr in YPO 4 in crystals with Pr concentrations of 0.1%, 1%, 2%, and 5%. We have found that the 1 D 2 level decay is purely radiative in the low-doped system. As the Pr concentration is increased, the 1 D 2 luminescence is quenched due to a cross-relaxation energy transfer between two Pr ions. The temporal behavior of the 1 D 2 luminescence following pulsed excitation has been monitored in each sample at temperatures between 30 K and 300 K, and all decay curves were fit to the Yokota–Tanimoto model. The decay times decrease as temperature increases, due to an increase in both the radiative rate and the energy transfer rate with temperature. There is little evidence of diffusion at any temperature, even in the more concentrated samples. We have also fit the decay curves using the LumiTrans computer simulation. A comparison of the fits to the decay curves of the two methods is presented. - Highlights: ► We present data on the decay of the 1 D 2 level of Pr in YPO 4 from 30–300 K. ► We determine the 1 D 2 cross-relaxation rate throughout that temperature range. ► Fits to the data indicate diffusion among the Pr ions is negligible. ► Radiative efficiencies of the 1 D 2 level are determined.

Thermal stability of the F centre in KC1 between 80 and 300 K; Estabilidad termica del centro F' en KC1 entre 80 y 300 K

Energy Technology Data Exchange (ETDEWEB)

Garcia Codovila, C

1974-07-01

After shining an F spark light of high intensity upon a coloured sample of KC1, the annealing of the induced F1 band and the decay of the induced luminescence are observed. This luminescence is produced by the electrons returning to the anion vacancies through the F* state. From the annealing characteristics of the F1 band between 80 and 300 K, we conclude that at least six thermally activated processes ase involved. The luminescence decay curves also show evidence of six the thermally activated processes which correlate quite wall in magnitude with those from the F1 band anneal. We conclude that the luminescence and annealing of the F1 band are aspects of the same process, and some explanations are suggested involving the interaction of F1 centres and electron traps. (Author) 41 refs.

Thermal stability of the F centre in KC1 between 80 and 300 K; Estabilidad termica del centro F' en KC1 entre 80 y 300 K

Energy Technology Data Exchange (ETDEWEB)

Garcia Codovila, C.

1974-07-01

After shining an F spark light of high intensity upon a coloured sample of KC1, the annealing of the induced F1 band and the decay of the induced luminescence are observed. This luminescence is produced by the electrons returning to the anion vacancies through the F* state. From the annealing characteristics of the F1 band between 80 and 300 K, we conclude that at least six thermally activated processes ase involved. The luminescence decay curves also show evidence of six the thermally activated processes which correlate quite wall in magnitude with those from the F1 band anneal. We conclude that the luminescence and annealing of the F1 band are aspects of the same process, and some explanations are suggested involving the interaction of F1 centres and electron traps. (Author) 41 refs.

Thermal stability of the F centre in KC1 between 80 and 300 K

International Nuclear Information System (INIS)

Garcia Codovila, C.

1974-01-01

After shining an F spark light of high intensity upon a coloured sample of KC1, the annealing of the induced F1 band and the decay of the induced luminescence are observed. This luminescence is produced by the electrons returning to the anion vacancies through the F* state. From the annealing characteristics of the F1 band between 80 and 300 K, we conclude that at least six thermally activated processes ase involved. The luminescence decay curves also show evidence of six the thermally activated processes which correlate quite wall in magnitude with those from the F1 band anneal. We conclude that the luminescence and annealing of the F1 band are aspects of the same process, and some explanations are suggested involving the interaction of F1 centres and electron traps. (Author) 41 refs

Dosimetry based on thermally and optically stimulated luminescence

International Nuclear Information System (INIS)

Agersnap Larsen, Niels

1999-01-01

Thermally Stimulated Luminescence (TL) and Optically Stimulated Luminescence (OSL) properties of quartz and α-Al 2 O 3 have been investigated. Anneling-induced OSL and TL sensitivity changes in quartz has been investigated by experiments and modelling. This study does not support a pre-dose effect to account for the observed annealing-induced sensitivity change. The experimental data indicates a more simple mechanism that involves alteration of the concentration of the defect centers. Results from modelling of removal or creation of defect centers comparing well with experimentally obtained data. Thermal quenching of luminescence for the main emission center, the F-center, in α-Al 2 O 3 :C has been investigated by analysing TL curves obtained at different heating rates. The thermal quenching dependence of luminescence is found to follow the classical Mott-Seitz expression. Basic investigations of OSL properties of αAl 2 O 3 :C, including: the thermal depth of the OSL traps, the temperature dependence of OSL, and the OSL stimulation spectra. Simultaneous measurements of TL and thermally stimulated conductivity (TSC) are presented for γ-irradiated αAl 2 O 3 :C. Activation energy analysis of the data reveals a superposition of several first-order TL and TSC peaks caused by release of charge carriers from a distribution of trapping states. Furthermore a description of an experimental method developed to determine the sign of the thermally released charge carriers has been presented. (au)

Natural and laboratory OSL growth curve–Verification of the basic assumption of luminescence dating

International Nuclear Information System (INIS)

Kijek, N.; Chruścińska, A.

2016-01-01

The basic assumption of luminescence dating is the equality between the growth curve of OSL generated by the natural radiation and the OSL growth curve reconstructed in laboratory conditions. The dose rates that generate the OSL in nature and in laboratory experiments differ by about ten orders of magnitude. Recently some discrepancies between the natural and laboratory growth curves have been observed. It is important to establish their reasons in order to introduce appropriate correction into the OSL dating protocol or to find a test that allows to eliminate the samples which should not be used for dating. For this purpose, both growth curves, natural and laboratory, were reconstructed by means of computer simulations of the processes occurring in the sample during its deposition time in environment as well as those which occur in a laboratory during dating procedure. The simulations were carried out for three models including one shallow trap, two OSL traps, one disconnected deep and one luminescence center. The OSL model for quartz can be more complex than the one used in the presented simulations, but in spite of that the results show effects of growth curves discrepancies similar to those observed in experiments. It is clear that the consistency of growth curves is not a general feature of the OSL processes, but rather a result of an advantageous configuration of trap parameters. The deep disconnected traps play the key role and their complete filling before the zeroing of OSL signal is a necessary condition of the growth curves' consistency. - Highlights: • Process of OSL growth curve generation in nature and in laboratory was simulated. • Discrepancies between the natural and the laboratory growth curves are observed. • Deep disconnected traps play the key role in growth curve inequality. • Empty deep traps before zeroing of OSL cause the inequality of growth curves.

Luminescence and energy transfer

Energy Technology Data Exchange (ETDEWEB)

Blasse, G; Bleijenberg, K C; Powell, R C

1980-01-01

This paper deals with the luminescence of uranate centres in solids. The luminescence properties are influenced by the coordination number of the hexavalent uranium ion and by the crystallographic surroundings of the uranate centre. Transitions playing a role in the luminescence processes within the octahedral UO/sub 6//sup 6 -/ group are discussed using the results from both theoretical and experimental studies on another octahedral uranium complex: UF/sub 6/. The luminescence of the octahedral uranate group in oxidic compounds is discussed. Attention is paid to the vibrational structure, which is observed in the luminescence spectra at low temperatures and to the temperature quenching of the luminescence. The temperature quenching of the uranate luminescence in uranium-doped tungstates with ordered perovskite structure can be described in terms of a three state single configurational coordinate diagram. The complicated luminescence spectra of uranium-activated sodium fluoride (NaF-U) crystals have been unraveled using chemical variation of the crystal compositions and using site selective laser excitation techniques. Four different luminescent uranate centres have been observed in NaF-U. A model for the configurations of the luminescent centres has been deduced using the results from ionic conductivity experiments.

Investigation of the yield process by deformation luminescence of X-ray irradiated KCl:Ca2+

International Nuclear Information System (INIS)

Nakamura, S.; Ida, K.; Ohgaku, T.

2011-01-01

It is found that deformation luminescence gives us information about the microscopic yield process of X-ray irradiated KCl:Ca 2+ . The stress-strain curve has a macroscopic yield point. But we find that luminescence appears to start before the macroscopic yield. This means that dislocation begin to move before the macroscopic yield because deformation luminescence is attributed to radiation-induced dislocation motion. The beginning of luminescence is considered to be the microscopic yield. Investigating the dependence of microscopic yield stress on strain rate and impurity concentration gives us additional information. The activation volume obtained from the dependence of microscopic yield stress on strain rate is comparable to the value estimated from the concentration of impurity. Then the dislocation starts to move overcoming impurity-vacancy dipoles as obstacles to dislocation motion. The dislocation density starts to increase at the microscopic yield point and then sharply increases to the macroscopic yield.

On the OSL curve shape and preheat treatment of electronic components from portable electronic devices

DEFF Research Database (Denmark)

Woda, Clemens; Greilich, Steffen; Beerten, Koen

2010-01-01

The shape of the OSL decay curve and the effect of longer time delays between accidental exposure and readout of alumina-rich electronic components from portable electronic devices are investigated. The OSL decay curve follows a hyperbolic decay function, which is interpreted as an approximation ...

The luminescence of CaWO4: Bi single crystals

International Nuclear Information System (INIS)

Zorenko, Yu.; Pashkovsky, M.; Voloshinovskii, A.; Kuklinski, B.; Grinberg, M.

2006-01-01

Influence of doping with Bi 3+ ions and Bi 3+ -Na + or Bi 3+ -Li + ions pairs on luminescence, emission kinetics and light yield of CaWO 4 crystals has been investigated. It has been shown that under excitation in the A-band at 272 and 287nm, related to the Bi 3+ ions absorption, the luminescence peaked at 468nm decaying with time τ=0.41μs is observed. For bismuth concentration 50-500ppm and the equimolar concentrations of the Bi 3+ ions accompanied by Na + or Li + ions compensators the significant suppression of the phosphorescence peaked at 520nm, related to the defect WO 3 -V O complex, and an improvement of scintillation characteristics of the CaWO 4 are noticed. Energy transfer from the defect WO 3 -V O and regular WO 4 2- oxy-anions to Bi 3+ ions have been observed at room temperatures and discussed

Synthesis and luminescence properties of novel LiSrPO{sub 4}:Dy{sup 3+} phosphor

Energy Technology Data Exchange (ETDEWEB)

Sun, Jiayue, E-mail: jiayue_sun@126.com [School of Science, Beijing Technology and Business University, Beijing 100048 (China); Zhang, Xiangyan [School of Science, Beijing Technology and Business University, Beijing 100048 (China); Xia, Zhiguo, E-mail: xiazg426@yahoo.com.cn [School of Materials Sciences and Technology, China University of Geosciences, Beijing 100083 (China); Du, Haiyan [School of Science, Beijing Technology and Business University, Beijing 100048 (China)

2011-11-15

Graphical abstract: Novel LiSrPO4:Dy{sup 3+} phosphors were synthesized by solid-state reaction, and Dy{sup 3+}-doped concentration dependent luminescence properties, concentration quenching effect and the decay times were investigated in detail. Highlights: {yields} LiSrPO{sub 4}:Dy{sup 3+} could be excited by UV light and exhibited blue and yellow emission. {yields} Concentration quenching effect of LiSrPO{sub 4}:Dy{sup 3+} samples were investigated in detail. {yields} Decay times are estimated to be 0.57-0.89 ms for Dy{sup 3+} in LiSrPO{sub 4} host. -- Abstract: Novel LiSrPO{sub 4}:Dy{sup 3+} phosphors for white light-emitting diodes (w-LEDs) were synthesized by the conventional solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the phase formation of LiSrPO{sub 4}:Dy{sup 3+} materials. Luminescence properties results showed that the phosphor could be efficiently excited by the UV-vis light region from 250 to 460 nm, and it exhibited blue (483 nm) and yellow (574 nm) emission corresponding to {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 15/2} transitions and {sup 4}F{sub 9/2} {yields} {sup 6}H{sub 13}/{sub 2} transitions, respectively. The luminescence intensity of LiSrPO{sub 4}:xDy{sup 3+} phosphor firstly increased and then decreased with increasing Dy{sup 3+} concentration, and reached the maximum at x = 0.03. It was found that concentration quenching occurred as a result of dipole-dipole interaction according to the Dexter's theory. The decay time was also determined for various concentrations of Dy{sup 3+} in LiSrPO{sub 4}.

Growth and luminescent properties of the Ce, Pr doped NaCl single crystals grown by the modified micro-pulling-down method

Energy Technology Data Exchange (ETDEWEB)

Yokota, Yuui, E-mail: y-yokota@tagen.tohoku.ac.j [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University/2-1-1, Katahira, Aoba-ku, Sendai (Japan); Yanagida, Takayuki; Fujimoto, Yutaka [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University/2-1-1, Katahira, Aoba-ku, Sendai (Japan); Nikl, Martin [Institute of Physics, Academy of Sciences of the Czech Republic/6253, Prague (Czech Republic); Yoshikawa, Akira [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University/2-1-1, Katahira, Aoba-ku, Sendai (Japan); New Industry Creation Hatchery Center (NICHe), Tohoku University/2-1-1, Katahira, Aoba-ku, Sendai (Japan)

2010-03-15

We have investigated luminescent properties of nondope, Ce and Pr doped NaCl [nondope NaCl, Ce:NaCl, Pr:NaCl] single crystals grown by a modified micro-pulling-down method with a removable chamber system. Nondope, Ce 1% and Pr 1% doped NaCl crystals with a single phase of NaCl structure were obtained and the crystals indicated general crystal quality by the X-ray rocking curve measurement. For the nondope NaCl and Pr:NaCl crystals, the transmittance spectra indicated almost more than 60% in the wavelength from 200 to 800 nm and an absorption of Ce{sup 3+} ion was observed in the transmittance spectrum of Ce:NaCl crystal. The emission spectrum originated from Ce{sup 3+} 5d-4f transition appeared around 300 nm in the photoluminescence spectrum and the decay time was 19.7 ns.

Electric field dependence of the total excimer luminescence of xenon excited below the atomic ionization limit

International Nuclear Information System (INIS)

Anon.

1987-01-01

In the spectral region of interest (i.e., 11.1 eV ≤ h nu ≤ 11.9 eV), the photoionization yield of electrons from excited-state dimers of xenon, increases monotonically to relatively high values (e.g., Y(11.7 eV) = 0.43 electrons/absorbed photon). It is also known however, that the luminescence intensity excited by photons in this region is quite high, even at low pressures. These two observations can be reconciled only by assuming that one of the processes leading to excimer luminescence involves dimer-ion + electron recombination. If this assumption is correct, application of an electric field, with concomitant collection of the free charges generated by the incident photons, should lead to a decrease in luminescence intensity; moreover, this decrease should follow the energy dependence of the photoionization yield function. The present report demonstrates experimentally that this is indeed the case. Such experiments combining luminescence and electric fields were made, until now, only by high-energy excitation. In this case the deconvolution of the various decay channels is hardly possible

Streamer chamber: pion decay

CERN Multimedia

1992-01-01

The real particles produced in the decay of a positive pion can be seen in this image from a streamer chamber. Streamer chambers consist of a gas chamber through which a strong pulsed electric field is passed, creating sparks as a charged particle passes through it. A magnetic field is added to cause the decay products to follow curved paths so that their charge and momentum can be measured.

Luminescence properties of Y3Al5O12:Ce nanoceramics

International Nuclear Information System (INIS)

Zorenko, Yu.; Voznyak, T.; Gorbenko, V.; Zych, E.; Nizankovski, S.; Dan'ko, A.; Puzikov, V.

2011-01-01

Comparative analysis of the luminescent properties of Y 3 Al 5 O 12 :Ce (YAG:Ce) transparent optical ceramics (OS) with those of single crystal (SC) and single crystalline film (SCF) analogues has been performed under excitation by pulsed synchrotron radiation in the fundamental absorption range of YAG host. It has been shown that the properties of YAG:Ce OC are closer to the properties of the SCF counterpart, where Y Al antisite defects are completely absent, rather than to the properties of SC of this garnet with large concentration of Y Al antisite defects. At the same time, the luminescence spectra of YAG:Ce OC show weak emission bands in the 200-470 nm range related to Y Al antisite defects and charged oxygen vacancies (F + and F centers). YAG:Ce OS also possesses significantly larger contribution of slow components in the Ce 3+ luminescence decay under high-energy excitation in comparison with SC and SCF of this garnet due to the involvement of antisite defects, charged oxygen vacancies as well as boundaries of grains in the energy transfer processes from the host to the Ce 3+ ions.

Variables and potential models for the bleaching of luminescence signals in fluvial environments

Science.gov (United States)

Gray, Harrison J.; Mahan, Shannon

2015-01-01

Luminescence dating of fluvial sediments rests on the assumption that sufficient sunlight is available to remove a previously obtained signal in a process deemed bleaching. However, luminescence signals obtained from sediment in the active channels of rivers often contain residual signals. This paper explores and attempts to build theoretical models for the bleaching of luminescence signals in fluvial settings. We present two models, one for sediment transported in an episodic manner, such as flood-driven washes in arid environments, and one for sediment transported in a continuous manner, such as in large continental scale rivers. The episodic flow model assumes that the majority of sediment is bleached while exposed to sunlight at the near surface between flood events and predicts a power-law decay in luminescence signal with downstream transport distance. The continuous flow model is developed by combining the Beer–Lambert law for the attenuation of light through a water column with a general-order kinetics equation to produce an equation with the form of a double negative exponential. The inflection point of this equation is compared with the sediment concentration from a Rouse profile to derive a non-dimensional number capable of assessing the likely extent of bleaching for a given set of luminescence and fluvial parameters. Although these models are theoretically based and not yet necessarily applicable to real-world fluvial systems, we introduce these ideas to stimulate discussion and encourage the development of comprehensive bleaching models with predictive power.

Tb{sup 3+}/Eu{sup 3+}: YF{sub 3} nanophase embedded glass ceramics: Structural characterization, tunable luminescence and temperature sensing behavior

Energy Technology Data Exchange (ETDEWEB)

Chen, Daqin, E-mail: dqchen@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018 (China); Wang, Zhongyi; Zhou, Yang [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018 (China); Huang, Ping, E-mail: phuang@fjirsm.ac.cn [State Key Laboratory of Structural Chemistry, Fujian Institute of Research on The Structure of Matter, Chinese Academy of Sciences, Fuzhou, Fujian 350002 (China); Ji, Zhenguo, E-mail: jizg@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou, 310018 (China)

2015-10-15

Tb{sup 3+}/Eu{sup 3+} co-doped transparent bulk glass ceramics containing orthorhombic β-YF{sub 3} nanocrystals were successfully synthesized by melt-quenching and subsequent heating. The partition of the active centers into the YF{sub 3} crystalline lattice was confirmed by elemental mapping in the scanning transmission electron microscope, emission spectra and decay curves. As a consequence, Tb{sup 3+} → Eu{sup 3+} energy transfer was demonstrated to be more efficient in the glass ceramic than in the precursor glass, which resulted in color tunable luminescence by simply modifying Eu{sup 3+} content and induced the linearly temperature-dependent fluorescence intensity ratio between the Tb{sup 3+}: {sup 5}D{sub 4} → {sup 7}F{sub 5} transition and the Eu{sup 3+}: {sup 5}D{sub 0} → {sup 7}F{sub 4} one in the Tb{sup 3+}/Eu{sup 3+} co-doped glass ceramic. It is expected that the investigated glass ceramic might be a promising candidate for solid-state lighting as well as optical temperature sensor. - Highlights: • Lanthanide doped glass ceramics containing YF{sub 3} nanocrystals were fabricated. • Tb{sup 3+} and Eu{sup 3+} dopants were confirmed to incorporate into YF{sub 3} lattice. • Tunable luminescence was realized via Tb{sup 3+} → Eu{sup 3+} energy transfer. • Linearly temperature-dependent fluorescence intensity ratio was detected.

Dosimetry based on thermally and optically stimulated luminescence

Energy Technology Data Exchange (ETDEWEB)

Agersnap Larsen, Niels

1999-01-01

Thermally Stimulated Luminescence (TL) and Optically Stimulated Luminescence (OSL) properties of quartz and {alpha}-Al{sub 2}O{sub 3} have been investigated. Anneling-induced OSL and TL sensitivity changes in quartz has been investigated by experiments and modelling. This study does not support a pre-dose effect to account for the observed annealing-induced sensitivity change. The experimental data indicates a more simple mechanism that involves alteration of the concentration of the defect centers. Results from modelling of removal or creation of defect centers comparing well with experimentally obtained data. Thermal quenching of luminescence for the main emission center, the F-center, in {alpha}-Al{sub 2}O{sub 3}:C has been investigated by analysing TL curves obtained at different heating rates. The thermal quenching dependence of luminescence is found to follow the classical Mott-Seitz expression. Basic investigations of OSL properties of {alpha}Al{sub 2}O{sub 3}:C, including: the thermal depth of the OSL traps, the temperature dependence of OSL, and the OSL stimulation spectra. Simultaneous measurements of TL and thermally stimulated conductivity (TSC) are presented for {gamma}-irradiated {alpha}Al{sub 2}O{sub 3}:C. Activation energy analysis of the data reveals a superposition of several first-order TL and TSC peaks caused by release of charge carriers from a distribution of trapping states. Furthermore a description of an experimental method developed to determine the sign of the thermally released charge carriers has been presented. (au) 8 tabs., 59 ills., 90 refs.

Near-infrared spectral downshifting in Sr$_{(3−x)}$(VO$_4$)

Indian Academy of Sciences (India)

infrared (NIR) radiation in Sr 3 (VO 4 ) 2 :Nd 3 + phosphor is reported. The prepared materials were characterized by X-ray powder diffraction(XRD) and photoluminescence (PL) properties along with steady state luminescence time decay curves ...

Photon cascade luminescence from Pr3+ ions in LiPrP4O12 polyphosphate

International Nuclear Information System (INIS)

Shalapska, T; Stryganyuk, G; Romanyshyn, Yu; Demchenko, P; Voloshinovskii, A; Trots, D; Gektin, A; Dorenbos, P

2010-01-01

The spectral-kinetic properties of luminescence from LiY 1-x Pr x P 4 O 12 (x = 1, 0.1) phosphors are studied in the 10-300 K temperature range upon excitation within the UV-VUV spectral range. The luminescence observed for LiPrP 4 O 12 at low temperatures is attributed to both intra-configurational 4f 2 → 4f 2 and inter-configurational 4f5d → 4f 2 radiative transitions of Pr 3+ . The temperature dependence of emission and the decay kinetics of Pr 3+ luminescence from LiY 1-x Pr x P 4 O 12 (x = 1, 0.1) phosphors are explained by temperature stimulated transitions from the 1 S 0 to the Pr 3+ 4f5d state. At low temperatures, the energy potential barrier between the 1 S 0 and 4f5d states is 0.014 eV for LiPrP 4 O 12 . The spectral overlap of the 1 S 0 and 4f5d states of Pr 3+ in LiY 0.9 Pr 0.1 P 4 O 12 determines the luminescence properties in the entire temperature range studied.

Defect-induced luminescence in sol-gel silica samples doped with Co(II) at different concentrations

Energy Technology Data Exchange (ETDEWEB)

Jimenez-Sandoval, S. [Centro de Investigacion y Estudios Avanzados, Queretaro, Apdo. Postal 1-798, Queretaro, Qro. 76001 (Mexico); Estevez, M. [Fisica Aplicada y Tecnologia Avanzada, UNAM, Apdo. Postal 1-1010, Queretaro, Qro. 76000 (Mexico); Pacheco, S. [Instituto Mexicano del Petroleo, Av. 100 metros (Mexico); Vargas, S. [Fisica Aplicada y Tecnologia Avanzada, UNAM, Apdo. Postal 1-1010, Queretaro, Qro. 76000 (Mexico); Rodriguez, R. [Fisica Aplicada y Tecnologia Avanzada, UNAM, Apdo. Postal 1-1010, Queretaro, Qro. 76000 (Mexico)], E-mail: rogelior@servidor.unam.mx

2007-12-20

The defect-induced luminescence properties of silica samples prepared by the sol-gel method and doped with Co(II) are reported. Silica monoliths doped with different concentrations of Co(II) were laser irradiated (He-Ne 632.8 nm) producing fluorescence. However, this fluorescence is exponentially reduced with the irradiation time, to practically disappear. The rate the fluorescence decays can be well modeled with a double exponential function of the irradiation time, containing two different relaxation times; a baseline is also required to take into account some residual fluorescence. The characteristic times involved in this luminescence quenching process are in the range of seconds. This luminescence suppression can be associated to the local heating produced by the laser irradiation when focused in a small area (2 {mu}m in diameter) on the sample. This heating process reduces physical (grain boundaries, surface states) and chemical (oxygen vacancies produced by the dopant) defects in the sample.

P 8: Table-top instrumentation for time-resolved luminescence spectroscopy of solids excited by soft X-ray from a laser induced plasma source and/or UV-VIS laser

International Nuclear Information System (INIS)

Bruza, P.; Fidler, V.; Nikl, M.

2010-01-01

The design and use of a novel, table-top UV-VIS luminescence spectrometer with two excitation sources is described: a soft X-ray/XUV pulse excitation from the laser-produced plasma in gas puff target of about 4 ns duration, and a conventional N 2 pulse laser excitation at 337 nm (or any other UV-VIS pulse laser excitation). The XUV plasma source generates photons of either quasi-monochromatic (N target, E = 430 eV) or wide (Ar target, E = 200 ∼ 600 eV) spectral range. A combination of both X-ray/XUV and UV-VIS excitation in one experimental apparatus allows to perform comparative luminescence spectra and kinetics measurements under the same experimental conditions. In order to demonstrate the spectrometer, the UV-VIS luminescence spectra and decay kinetics of cerium doped Lu 3 Al 5 O 12 single crystal (LuAG:Ce) scintillator excited by XUV and UV radiation were acquired. Luminescence of doped Ce 3+ ions was studied under XUV 430 eV excitation from the laser-produced nitrogen plasma, and compared with the luminescence under 337 nm (3,68 eV) UV excitation from nitrogen laser. In the former case the excitation energy is deposited in the LuAG host, while in the latter the 4f-5d transition of Ce 3+ is directly excited. Furthermore, LuAG:Ce single crystals and single crystalline films luminescence decay profiles are compared and discussed. (authors)

Highly sensitive time resolved singlet oxygen luminescence detection using LEDs as the excitation source

International Nuclear Information System (INIS)

Hackbarth, S; Schlothauer, J; Preuss, A; Röder, B

2013-01-01

For the first time singlet oxygen luminescence kinetics in living cells were detected at high precision using LED light for excitation. As LED technology evolves, the light intensity emitted by standard LEDs allows photosensitized singlet oxygen luminescence detection in solution and cell suspensions. We present measurements superior to those of most actual laser powered setups regarding precision of singlet oxygen kinetics in solutions and cell suspensions. Data presented here show that LED based setups allow the determination of the photosensitizer triplet and singlet oxygen decay times in vitro with an accuracy of 0.1 μs. This enables monitoring of the photosensitizer efficiency and interaction with the cellular components using illumination doses small enough not to cause cell death. (letter)

Decay power evaluation for licensing analysis

International Nuclear Information System (INIS)

Tran, H.; Schrock, V.E.

1987-01-01

The ANSI/ANS 5.1-1979 Standard on Decay Power in shutdown reactors has been available as the basis for accident analysis for the past 7 yr. The US Nuclear Regulatory Commission has made a commitment to use this standard in new licensing approaches and has approved a licensing model for boiling water. More sweeping changes in the licensing rules are currently under review that will involve the use of best-estimate models and a statistical evaluation of the uncertainty (95% confidence level) in the key results. The structure of the decay power standard is well suited for such applications because it provides a statistically meaningful uncertainty in the decay power from fission products. The normalized decay power is a function specific to each point in the reactor volume due to the fact that the fuel composition develops a spatial dependence as burnup proceeds and decay power depends on the mix of fissioning nuclides. For reactor safety calculations it is desirable to employ a single temporal decay power function for the whole core inasmuch as many variations of accident parameters are required. This is the usual approach in large system thermal-hydraulics codes. Such a single representative or generic curve for a specified total operating power history can be acceptable but at the expense of some increase in the uncertainty. In this paper, the author present a method of evaluating the additional uncertainty in the decay power associated with use of a generic curve

SrAl2O4:Eu2+ (1%) luminescence under UV, VUV and electron beam excitation

Science.gov (United States)

Nazarov, M.; Mammadova, S.; Spassky, D.; Vielhauer, S.; Abdullayeva, S.; Huseynov, A.; Jabbarov, R.

2018-01-01

This paper reports the luminescence properties of nanosized SrAl2O4:Eu2+ (1%) phosphors. The samples were prepared by combustion method at 600 °C, followed by annealing of the resultant combustion ash at 1000 °C in a reductive (Ar + H2) atmosphere. X-ray diffraction (XRD), photo luminescence (PL) and cathodoluminescence (CL) analysis and thermal stimulated luminescence (TSL) method were applied to characterize the phosphor. For the first time a peak at 375 nm was observed in CL spectra of SrAl2O4:Eu2+ (1%) nanophosphors. Luminescence excitation spectra analysis have shown that this peak is related to crystal defects. Also in TSL curve one strong peak was observed in the region above room temperature (T = 325 K), which is attributed to lattice defects, namely oxygen vacancies. A green LED was fabricated by the combination of the SrAl2O4:Eu2+ (1%) nanosized phosphor and a 365 nm UV InGaN chip.

Study of charmonium rare decays

International Nuclear Information System (INIS)

Brient, J.C.

1986-09-01

This thesis presents the study of rare decays of charmonium states formed in the interaction of an antiproton beam with an hydrogen gas jet target. Electromagnetic final states are used to sign the charmonium state formation (e + e - , e + e - + Χ, γγ). The selection of events used a two arms non magnetic spectrometer, with a charged track system, a threshold Cerenkov counter to tag the electron (positron), and an e.m. calorimeter. Energy scan technic have been used to observe the resonant formation through the excitation curves. Parameters of the states (mass, total and partial widths) are extracted from these curves using a statistical analysis. Two types of decays have been studied in this thesis: 1 P 1 charmonium state decay to the ψ (signed by its e + e - decay). In the energy scan around the center of gravity of the P charmonium states, we observe a cluster of 5 events, in a narrow mass range. This cluster correspond to a 2.7 σ signal. The most probable interpretation of this signal is given by a narrow resonance, with a mass of 3526. MeV. Due to the properties (mass, width and decay) of this signal, this could be interpreted as the 1 P 1 charmonium state. 2 photons decay of the η c and Χ 2 . 22 γγ events are observed, 15 in the η c region, and 7 in the Χ 2 region. This sample is interpreted as a direct observation of η c and Χ 2 decay into γγ. Parameters of these decays, (γγ partial width), are extracted using a maximum likekihood analysis. Theoretical models of charmonium explain correctly the properties of the charmonium, including the results presented in this thesis. 57 refs [fr

Limits to depletion of blue-green light stimulated luminescence in feldspars: Implications for quartz dating

DEFF Research Database (Denmark)

Jain, M.; Singhvi, A.K.

2001-01-01

stimulation curve of otherwise pure quartz. In this study, the functional relationship between the infra-red stimulated luminescence (IRSL) and BGSL of feldspars, (1) at different preheats, and (2) with IR bleaching at different stimulation temperatures and durations, is examined. The results suggest two trap...

Persistent luminescence and thermoluminescence of UV/VIS -irradiated SrAl2O4: Eu2+, Dy3+ phosphor

International Nuclear Information System (INIS)

Pereyda-Pierre, C.; Meléndrez, R.; García, R.; Pedroza-Montero, M.; Barboza-Flores, M.

2011-01-01

The persistent luminescence and thermoluminescence properties of SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors excited with UV–VIS light in the 200–500 nm region were investigated. The thermoluminescence glow curve was found to be composed of peaks around 70, 125 and 245 °C. The persistent luminescence and thermoluminescence excitation spectra exhibited a broad band around 300–500 nm centered at 400 and 420 nm respectively. A linear behavior of the integrated thermoluminescence intensity and persistent luminescence versus irradiation time was found for the first 60 s. The charge detrapping from the 70 °C trapping levels was the major contributor to the observed persistent luminescence at room temperature. The SrAl 2 O 4 : Eu 2+ , Dy 3+ phosphors have suitable properties to be applied as storage and persistent luminescence UV–VIS irradiation dose phosphor. -- Highlights: ► SrAl 2 O 4 :Eu 2+ , Dy 3+ persistent luminescence and thermoluminescence was measured. ► The phosphor was irradiated with UV–VIS photons in the 200–500 nm wavelength range. ► SrAl 2 O 4 :Eu 2+ , Dy 3+ behaves adequately as persistent and storage UV–VIS dosimeter. ► The persistent luminescence dosimetry does not require heat or light stimulation.

Long-time Luminescence Kinetics of Localized excitons and conduction Band Edges Smearing in ZnSe(1-c)Tec Solid Solutions

DEFF Research Database (Denmark)

Klochikhin, O.; Ogloblin, S. G.; Permogorov, S.

2000-01-01

It is shown that the integrated luminescence intensity of localized excitons in solid solutions ZnSe(1 - c)Tec has a component slowly decaying with time. After the excitation above the mobility threshold, the long-time intensity decreases exponentially, with a fractional exponent changing from...

Structural and luminescence properties of Mn2+ ions doped calcium zinc borophosphate glasses

International Nuclear Information System (INIS)

Wan, Ming Hua; Wong, Poh Sum; Hussin, Rosli; Lintang, Hendrik O.; Endud, Salasiah

2014-01-01

Highlights: • FT-IR revealed that the network structures are from borate and phosphate network. • The PL spectrum exhibits a green emission band at 582 nm ( 4 T 1g → 6 A 1g ). • As the concentration of Mn 2+ ions is increased, the emission band had been red shifted. • These glasses are found to have potential applications as luminescent optical materials. - Abstract: Calcium zinc borophosphate glasses (CaZnBP) doped with various concentrations of Mn 2+ ions and borate and phosphate as variable were prepared using conventional melt quenching technique. The structure of obtained glasses were examined by means of use: X-ray diffraction (XRD) and fourier transform infrared (FT-IR). XRD analysis confirmed amorphous nature of glass samples. The FT-IR spectra reveals the presence of both borate and phosphate vibrational modes in the prepared glasses. The doping of Mn 2+ ions (2–10 mol%) shows no significant changes in the main IR vibrational bands. Optical properties were studied by measuring the near infrared photoluminescence (PL) spectra. CaZnBP glasses exhibited intense green emission peak (582 nm) (tetrahedral symmetry), which is assigned to a transition from the upper 4 T 1g → 6 A 1g ground state of Mn 2+ ions. As the concentration of Mn 2+ ions increases, the emission band increases from 582 nm to 650 nm and exhibited a red light emission (octahedral symmetry). The decay curves of 4 T 1g level were examined for all concentrations and the measured lifetimes are found to depend strongly on Mn 2+ concentrations. From the emission characteristic parameters of 6 A 1g (S) level, it shows that the CaZnBP glasses could have potential applications as luminescent optical materials, visible lasers and fluorescent display devices

Luminescence of Lanthanoides (Rare-earth elements) – Probes of structural variations in minerals

International Nuclear Information System (INIS)

Lenz, C.

2015-01-01

This cumulative PhD thesis summarises several individual studies on the luminescence of REE (rare-earth elements; i.e., trivalent lanthanoides), which are typically incorporated in accessory minerals such as zircon, titanite, monazite–(Ce) and xenotime–(Y). A main objective of these studies is to examine the powerfulness of REE luminescence-spectroscopy as structural probe. In particular, this concerns the potential use of REE3+ emissions in characterising structural disorder of their accessory host minerals as caused by radiation damage and/or compositional heterogeneity. Especially the former (i.e., mineral disorder due to radiation damage) is of interest to Earth and materials scientists, for instance for the understanding of changed physicochemical properties of initially crystalline materials that are affected by structural damage as caused by the radioactive decay of actinides. Moreover, a substantial contribution of the studies presented lies in the field of basic properties of the REE luminescence of natural accessory minerals. First, the investigations have addressed the identification of diverse REE species in diverse natural host minerals (which is done using synthetic REE-doped analogues). Second, factors that may bias the quantitative estimation of spectroscopic parameters have been studied, including effects of experimental parameters (crystal orientation and temperature) and the samples’ compositional heterogeneity. The results will be particularly useful to the growing community of Earth scientists who apply REE luminescence-spectroscopy in studying geological materials. (author) [de

Decay Curves and Half-Lives of Gamma-Emitting States from a Study of Prompt Fission Gamma Radiation

Energy Technology Data Exchange (ETDEWEB)

Albinsson, H [Chalmers Univ. of Technology, Goeteborg (SE)

1971-04-15

Measurements were made on the time distributions of the prompt gamma radiation emitted from fragments in the thermal-neutron induced fission of 235U. The gamma radiation emitted during different time intervals after the fission event was studied with the help of a collimator, the position of which was changed along the path of the fragments. In this way decay curves were obtained from which half-lives could be estimated. Time components with half-lives of 7.5, 18 and 60 ps were found and their relative intensities were calculated. Half-lives and associated intensities are in good agreement with earlier data from uranium and californium fission. Problems involved in this type of study are discussed. The collimator technique has proved to be effective for determination of half lives down to less than 10 ps

Luminescent beam stop

Energy Technology Data Exchange (ETDEWEB)

Bryant, Diane; Morton, Simon A.

2017-10-25

This disclosure provides systems, methods, and apparatus related to beam stops. In one aspect, a device comprises a luminescent material, a beam stop plate, and an optical fiber. The luminescent material is a parallelepiped having a first side and a second side that are squares and having a third side that is a rectangle or a square. The first side and the second side are perpendicular to the third side. The beam stop plate is attached to the first side of the luminescent material. The optical fiber has a first end and a second end, with the first end of the optical fiber attached to the third side of the luminescent material.

Luminescence of Ce.sup.3+./sup.- and Eu.sup.2+./sup.- doped silica glassesunder UV and X-ray excitation

Czech Academy of Sciences Publication Activity Database

Chewpraditkul, W.; Shen, Y.; Chen, D.; Nikl, Martin; Beitlerová, Alena

2013-01-01

Roč. 15, 1-2 (2013), s. 94-98 ISSN 1454-4164 R&D Projects: GA MŠk LH12185 Institutional support: RVO:68378271 Keywords : Ce 3+ * Eu 2+ * luminescence * photoluminescence decay * porous materials * scintillation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.563, year: 2013

Luminescence lifetimes in quartz: dependence on annealing temperature prior to beta irradiation

International Nuclear Information System (INIS)

Galloway, R.B.

2002-01-01

It is well known that the thermal history of a quartz sample influences the optically stimulated luminescence sensitivity of the quartz. It is found that the optically stimulated luminescence lifetime, determined from time resolved spectra obtained with pulsed stimulation, also depends on past thermal treatment. For samples at 20 deg. C during stimulation, the lifetime depends on beta dose and on duration of preheating at 220 deg. C prior to stimulation for quartz annealed at 600 deg. C and above, but is independent of these factors for quartz annealed at 500 deg. C and below. For stimulation at higher temperatures, the lifetime becomes shorter if the sample is held at temperatures above 125 deg. C during stimulation, in a manner consistent with thermal quenching. A single exponential decay is all that is required to fit the time resolved spectra for un-annealed quartz regardless of the temperature during stimulation (20-175 deg. C), or to fit the time resolved spectra from all samples held at 20 deg. C during stimulation, regardless of annealing temperature (20-1000 deg. C). An additional shorter lifetime is found for some combinations of annealing temperature and temperature during stimulation. The results are discussed in terms of a model previously used to explain thermal sensitisation. The luminescence lifetime data are best explained by the presence of two principal luminescence centres, their relative importance depending on the annealing temperature, with a third centre involved for limited combinations of annealing temperature and temperature during stimulation

Mid-IR Lasers: Challenges Imposed by the Population Dynamics of the Gain System

Science.gov (United States)

2010-09-01

MicroSystems (IOMS) Central-Field Approximation: Perturbations 1. a) Non-centrosymmetric splitting (Coulomb interaction) ⇒ total orbital angular momentum b...Accordingly: ⇒ total electron-spin momentum 2. Spin-orbit coupling (“LS” coupling) ⇒ total angular momentum lanthanides: intermediate coupling (LS / jj) 3...MicroSystems (IOMS) Luminescence Decay Curves Rate-equation for decay: Solution ( Bernoulli -Eq.): Linearized solution: T. Jensen, Ph.D. Thesis, Univ. Hamburg

Analysis of luminescence from common salt (NaCl) for application to retrospective dosimetry

International Nuclear Information System (INIS)

Spooner, N.A.; Smith, B.W.; Williams, O.M.; Creighton, D.F.; McCulloch, I.; Hunter, P.G.; Questiaux, D.G.; Prescott, J.R.

2011-01-01

Thermoluminescence (TL), Optically-Stimulated Luminescence (OSL) and Infrared-Stimulated Luminescence (IRSL) emitted from a set of 19 salt (NaCl) samples were studied for potential application to retrospective dosimetry. TL emission spectra revealed intense TL emissions from most samples, centred on 590 nm; UV and blue emissions were also found. Significant thermally-induced sensitivity changes were observed and TL, OSL and IRSL growth curves were measured. Pulse anneal analysis was performed, as was quantitative imaging of the TL, OSL and IRSL to assess sample heterogeneity. Kinetic analysis found lifetimes at 20 °C of the 200 °C and 240 °C TL peaks to be 0.6 ka and 4 ka respectively; sufficient for application to retrospective dosimetry.

A method for searching the possible deviations from exponential decay law

International Nuclear Information System (INIS)

Tran Dai Nghiep; Vu Hoang Lam; Tran Vien Ha

1993-01-01

A continuous kinetic function approach is proposed for analyzing the experimental decay curves. In the case of purely exponential behaviour, the values of kinetic function are the same at different ages of the investigated radionuclide. The deviation from main decay curve could be found by a comparison of experimental kinetic function values with those obtained in purely exponential case. (author). 12 refs

Statistical analysis of time-resolved emission from ensembles of semiconductor quantum dots: Interpretation of exponential decay models

DEFF Research Database (Denmark)

Van Driel, A.F.; Nikolaev, I.S.; Vergeer, P.

2007-01-01

We present a statistical analysis of time-resolved spontaneous emission decay curves from ensembles of emitters, such as semiconductor quantum dots, with the aim of interpreting ubiquitous non-single-exponential decay. Contrary to what is widely assumed, the density of excited emitters...... and the intensity in an emission decay curve are not proportional, but the density is a time integral of the intensity. The integral relation is crucial to correctly interpret non-single-exponential decay. We derive the proper normalization for both a discrete and a continuous distribution of rates, where every...... decay component is multiplied by its radiative decay rate. A central result of our paper is the derivation of the emission decay curve when both radiative and nonradiative decays are independently distributed. In this case, the well-known emission quantum efficiency can no longer be expressed...

Further investigations into pulsed optically stimulated luminescence from feldspars using blue and green light

DEFF Research Database (Denmark)

Ankjærgaard, Christina; Jain, Mayank; Kalchgruber, R.

2009-01-01

The purpose of this paper is to investigate characteristics of luminescence signals resulting from pulsed optical stimulation of feldspars and thereby to understand the underlying processes giving rise to the signal. Fourteen different feldspar specimens were investigated using time-resolved opti......The purpose of this paper is to investigate characteristics of luminescence signals resulting from pulsed optical stimulation of feldspars and thereby to understand the underlying processes giving rise to the signal. Fourteen different feldspar specimens were investigated using time...... suggests that the TR-OSL signal decay is governed by the recombination process and not by the excited state lifetime. Furthermore data from the TR-OSL signal dependence on stimulation time and preheat temperature suggest that the recombination process may not be a sum of exponentials, although the model...... cannot be rejected definitively....

Investigations on luminescence behavior of Er3+/Yb3+ co-doped boro-tellurite glasses

Science.gov (United States)

Maheshvaran, K.; Arunkumar, S.; Venkata Krishnaiah, K.; Marimuthu, K.

2015-01-01

Er3+/Yb3+ co-doped boro-tellurite glasses with the chemical composition 30TeO2+(24 - x)B2O3 + 15SrO + 10BaO + 10Li2O + 10LiF + 1Er2O3 + xYb2O3 (where x = 0, 0.1, 0.5, 1 and 2 in wt%) have been prepared and their luminescence behavior were studied and reported. Absorption spectral measurements have been used to derive the Judd-Ofelt (JO) intensity parameters from the experimental and calculated oscillator strength values following the JO theory. The various lasing parameters such as stimulated emission cross-section (σEp), experimental and calculated branching ratios (βR) and radiative lifetime (τcal) for the 2H9/2 → 4I15/2, 4S3/2 → 4I15/2 and 4I13/2 → 4I15/2 emission transitions were determined using the JO intensity parameters. The absorption and emission cross-section values for the 4I13/2 → 4I15/2 emission band have been calculated using McCumbar theory and the Gain cross-section for the 4I13/2 → 4I15/2 emission transition also obtained. The upconversion emission mechanism have been studied through various energy transfer processes and the intensity of the upconversion emission transitions are found to increase with the increase in Yb3+ ion concentration. The luminescence decay curves corresponding to the 4I13/2 → 4I15/2 transition of the Er3+/Yb3+ co-doped boro-tellurite glasses under 980 nm excitation wavelength have also been studied and reported in the present work.

Persistent luminescence, TL and OSL characterization of beta irradiated SrAl2O4:Eu2+, Dy3+ combustion synthesized phosphor

International Nuclear Information System (INIS)

Zúñiga-Rivera, N.J.; García, R.; Rodríguez-Mijangos, R.; Chernov, V.; Meléndrez, R.; Pedroza-Montero, M.; Barboza-Flores, M.

2014-01-01

The persistent luminescence (PLUM), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of strontium aluminates co-doped with Eu +2 and Dy +3 exposed to beta radiation is reported. The phosphor was synthesized by the combustion synthesis method employing a highly exothermic redox reaction between the metal nitrates [Al(NO 3 ) 3 , Sr(NO 3 ) 2 , Eu(NO 3 ) 3 and Dy(NO 3 ) 3 ] and organic fuel carbohydrazide (CH 6 N 4 O). The long decay PLUM emission, TL and OSL were measured as a function of beta radiation dose. A wide emission band centered at 510 nm (green) related to Eu 2+ ions and lattice defects were observed for the synthesized samples. The presence of a variety of defects and aggregates were responsible for the observed broad 100 °C peaked TL glow curve of the irradiated sample which is composed of several overlapped TL peaks. The existence of multiple trapping levels, with different trapping/detrapping probabilities, is behind the particular features for the PLUM, TL and OSL emissions. We conclude that in the SrAl 2 O 4 :Eu 2+ , Dy 3+ phosphors, the low temperature TL peaked around 30–75 °C is responsible for the PLUM emission and those around 100 °C were related to very stable trapping states which provide suitable radiation storage properties to be used as a PLUM/TL/OSL radiation phosphor

Limestone: some observations on luminescence in the region of 360 nm

International Nuclear Information System (INIS)

Galloway, R.B.

2003-01-01

An empirical study of luminescence around 360 nm from limestone is presented. Thermoluminescence glow curves from natural limestone show broad peaks at 440 deg. C, 350 deg. C, 530 deg. C and 286 deg. C in order of decreasing amplitude in contrast to the usual observation, for luminescence around 535 nm, of a sharp peak at 286 deg. C with a broader less intense peak at 350 deg. C. Recuperation occurs around 350 deg. C and 525 deg. C, which has a time dependence consistent with quantum tunnelling. Dependent on the history of heating and light exposure of the sample, sharp peaks at about 325 deg. C and 425 deg. C can be observed. Laboratory irradiated limestone shows a peak at 140 deg. C. The stimulation of luminescence by light of 470 nm with preheating at 145 deg. C for 300 s, shows an increasing signal for successive cycles of measurement associated with the heating, light exposure having little influence. Beta irradiation of a sample, with the same measurement conditions, gives a signal which increases in proportion to radiation dose but which does not survive storage for 17 h. Time resolved luminescence spectra, with no preheating, show a luminescence lifetime between stimulation and emission of less than a few μs for natural limestone, and an exponential increase in signal with increase in temperature (over the rang 20-167 deg. C) during stimulation. A signal proportional to laboratory applied beta dose is measurable at room temperature, with lifetime between stimulation and emission of this signal of 35 μs, but it does not survive heating to 100 deg. C

Measuring modulated luminescence using non-modulated stimulation: Ramping the sample period

DEFF Research Database (Denmark)

Poolton, N.R.J.; Bøtter-Jensen, L.; Andersen, C.E.

2003-01-01

. Directly analogous results to LM-OSL can, however, be achieved with non-modulated excitation sources, by ramping the sample period (RSP) of luminescence detection. RSP-OSL has the distinct advantage over LM-OSL in that, since the excitation remains at full power, data accumulation times (that can...... be considerable) can be reduced by typically 50%. RSP methods are universally applicable and can be employed, for example, where the excitation source is constant heat, rather than light: here, iso-thermal decay of phosphorescence becomes recorded as a sequence of peaks, corresponding to de-trapping of charge...

Delayed Luminescence and Biophotons from Biological Materials

Science.gov (United States)

Knoesel, Ernst; Hann, Patrick; Garzon, Maria; Pfeiffer, Erik; Lofland, Samuel

2008-03-01

There has recently been increased interest in the field of biophotonics, since it is a non-invasive technique. Many biological systems, such as yeast, bacteria, leaves, seeds, and algae display the unusual phenomenon of a weak, delayed luminescence on the timescale of seconds to minutes after transient illumination. It is also observed that the time decay of the biophotonic emission is not exponential, even after the delay, and that there can be oscillations in intensity with time, which depend on the duration of the illumination. Results from two types of yeast, i.e. bread yeast, and saccharomyces, as well as those from several types of algae are presented. Possible mechanisms for the source of the ultraweak photon emission are discussed.

Luminescence detection of shellfish

International Nuclear Information System (INIS)

Sanderson, D.C.W.; Carmichael, L.A.; Spencer, J.Q.; Naylor, J.D.

1996-01-01

The Scottish Universities Research and Reactor Centre (SURRC) has been active in the development and application of luminescence techniques in the detection of irradiated foods, in support of UK legislation. Thermoluminescence (TL), photostimulated luminescence (PSL) and photo-transfer luminescence (PTTL) are radiation-specific phenomena which arise due to energy stored by trapped charge carriers following irradiation. The energy released following stimulation is accompanied by detectable luminescence. The TL method involves preparation of pure silicate extracts from the sample and subsequent TL analysis, whereas PSL uses stimulation by electromagnetic radiation (visible, or near visible wavelengths) thus avoiding heating the sample. (author)

Spectroscopic and visible luminescence properties of rare earth ions in lead fluoroborate glasses

Energy Technology Data Exchange (ETDEWEB)

Anjaiah, G. [Department of Physics, Osmania University, Hyderabad 500007 (India); Nayab Rasool, SK. [Department of Physics, Sri Venkateswara University, Tirupati 517502 (India); Kistaiah, P., E-mail: pkistaiah@yahoo.com [Department of Physics, Osmania University, Hyderabad 500007 (India)

2015-03-15

The lanthanide doped lead lithium calcium zinc fluoroborate glasses (LLCZFB:Ln) of composition 20PbF{sub 2}+10Li{sub 2}O+5Cao+5ZnO+59B{sub 2}O{sub 3}+1Ln{sub 2}O{sub 3} (where Ln=Sm, Eu and Dy in mol%) were prepared by conventional melt quench technique. The amorphous nature of these glasses was confirmed by X-ray diffraction studies. The glass transition temperatures (T{sub g}) were studied by DSC analysis. The glass structure and spectroscopic properties were investigated using optical absorption, vibrational and fluorescence spectra. The FT-IR spectra and Raman spectra reveal the presence of BO{sub 3}, BO{sub 4} and non-bridging oxygen's. The Judd–Ofelt intensity parameters Ω{sub λ} (λ=2, 4, 6) were determined from the spectral intensities of absorption bands. These parameters were used to calculate the radiative parameters such as radiative transition probability (A{sub R}), radiative life time (τ{sub R}) and branching ratio (β{sub r}) for various excited luminescent states of rare earth ions. The visible emission spectra for different rare earth ions were recorded by exciting the samples at different wavelengths and the decay rates for the different rare earth ions were measured. Using the emission spectra, full width half maxima (FWFM), stimulated emission cross section (σ{sup E}{sub p}) were evaluated. The nature of decay profiles of {sup 4}F{sub 9/2}, {sup 4}G{sub 5/2} and {sup 5}D{sub 0} states of Dy, Sm and Eu ions respectively are analyzed. Comparison of luminescence features of these glasses and also with those reported for different glass hosts indicates that the LLCZFB:Dy glass has strong luminescence in the visible region. - Highlights: • LLCZFB:Ln glasses are prepared with Ln: Sm, Eu and Dy. • Glasses are characterized by XRD, FTIR, Raman, absorption and emission spectra. • J–O theory is used to calculate different radiative properties. • Green, yellow and red emissions are observed. • Glasses are useful for the development

Spectral Analysis of Chinese Medicinal Herbs Based on Delayed Luminescence

Directory of Open Access Journals (Sweden)

Jingxiang Pang

2016-01-01

Full Text Available Traditional Chinese medicine (TCM plays a critical role in healthcare; however, it lacks scientific evidence to support the multidimensional therapeutic effects. These effects are based on experience, and, to date, there is no advanced tool to evaluate these experience based effects. In the current study, Chinese herbal materials classified with different cold and heat therapeutic properties, based on Chinese medicine principles, were investigated using spectral distribution, as well as the decay probability distribution based on delayed luminescence (DL. A detection system based on ultraweak biophoton emission was developed to determine the DL decay kinetics of the cold and heat properties of Chinese herbal materials. We constructed a mathematical model to fit the experimental data and characterize the properties of Chinese medicinal herbs with different parameters. The results demonstrated that this method has good reproducibility. Moreover, there is a significant difference (p<0.05 in the spectral distribution and the decay probability distribution of Chinese herbal materials with cold and heat properties. This approach takes advantage of the comprehensive nature of DL compared with more reductionist approaches and is more consistent with TCM principles, in which the core comprises holistic views.

Luminescence and energy transfer of Tb3+-doped BaO-Gd2O3-Al2O3-B2O3-SiO2 glasses.

Science.gov (United States)

Zuo, Chenggang; Huang, Jinze; Liu, Shaoyou; Xiao, Anguo; Shen, Youming; Zhang, Xiangyang; Zhou, Zhihua; Zhu, Ligang

2017-12-05

Transparent Tb 3+ -doped BaO-Gd 2 O 3 -Al 2 O 3 -B 2 O 3 -SiO 2 glasses with the greater than 4g/cm 3 were prepared by high temperature melting method and its luminescent properties have been investigated by measured UV-vis transmission, excitation, emission and luminescence decay spectra. The transmission spectrum shows there are three weak absorption bands locate at about 312, 378 and 484nm in the glasses and it has good transmittance in the visible spectrum region. Intense green emission can be observed under UV excitation. The effective energy transfer from Gd 3+ ion to Tb 3+ ion could occur and sensitize the luminescence of Tb 3+ ion. The green emission intensity of Tb 3+ ion could change with the increasing SiO 2 /B 2 O 3 ratio in the borosilicate glass matrix. With the increasing concentration of Tb 3+ ion, 5 D 4 → 7 F J transitions could be enhanced through the cross relaxation between the two nearby Tb 3+ ions. Luminescence decay time of 2.12ms from 546nm emission is obtained. The results indicate that Tb 3+ -doped BaO-Gd 2 O 3 -Al 2 O 3 -B 2 O 3 -SiO 2 glasses would be potential scintillating material for applications in X-ray imaging. Copyright © 2017 Elsevier B.V. All rights reserved.

Further investigations into pulsed optically stimulated luminescence from feldspars using blue and green light

International Nuclear Information System (INIS)

Ankjaergaard, C.; Jain, M.; Kalchgruber, R.; Lapp, T.; Klein, D.; McKeever, S.W.S.; Murray, A.S.; Morthekai, P.

2009-01-01

The purpose of this paper is to investigate characteristics of luminescence signals resulting from pulsed optical stimulation of feldspars and thereby to understand the underlying processes giving rise to the signal. Fourteen different feldspar specimens were investigated using time-resolved optically stimulated luminescence (TR-OSL), and these signals can be mathematically described as a sum of 4 exponential components (a, b, c, d). The slowest component, d, increases with the duration of the light pulse as expected from the exponential model. The stimulation temperature dependence experiment suggests that the TR-OSL signal decay is governed by the recombination process and not by the excited state lifetime. Furthermore data from the TR-OSL signal dependence on stimulation time and preheat temperature suggest that the recombination process may not be a sum of exponentials, although the model cannot be rejected definitively.

Dark Matter Decays from Nonminimal Coupling to Gravity.

Science.gov (United States)

Catà, Oscar; Ibarra, Alejandro; Ingenhütt, Sebastian

2016-07-08

We consider the standard model extended with a dark matter particle in curved spacetime, motivated by the fact that the only current evidence for dark matter is through its gravitational interactions, and we investigate the impact on the dark matter stability of terms in the Lagrangian linear in the dark matter field and proportional to the Ricci scalar. We show that this "gravity portal" induces decay even if the dark matter particle only has gravitational interactions, and that the decay branching ratios into standard model particles only depend on one free parameter: the dark matter mass. We study in detail the case of a singlet scalar as a dark matter candidate, which is assumed to be absolutely stable in flat spacetime due to a discrete Z_{2} symmetry, but which may decay in curved spacetimes due to a Z_{2}-breaking nonminimal coupling to gravity. We calculate the dark matter decay widths and we set conservative limits on the nonminimal coupling parameter from experiments. The limits are very stringent and suggest that there must exist an additional mechanism protecting the singlet scalar from decaying via this gravity portal.

Luminescence of highly excited nonpolar a-plane GaN and AlGaN/GaN multiple quantum wells

International Nuclear Information System (INIS)

Jursenas, S.; Kuokstis, E.; Miasojedovas, S.; Kurilcik, G.; Zukauskas, A.; Chen, C.Q.; Yang, J.W.; Adivarahan, V.; Asif Khan, M.

2004-01-01

Carrier recombination dynamics in polar and nonpolar GaN epilayers and GaN/AlGaN multiple quantum wells grown over sapphire substrates with a various crystallographic orientation were studied under high photoexcitation by 20 ps laser pulses. The transient luminescence featured a significant enhancement on nonradiative recombination of free carriers for nonpolar a-plane GaN epilayers compared to conventional c-plane samples. The epitaxial layer overgrowth technique was demonstrated to significantly improve the quality of nonpolar a-plane films. This was proved by more than 40-fold increase in luminescence decay time (430 ps compared to ≤ 10 ps in the ordinary a-plane epilayer). Under high-excitation regime, a complete screening of built-in electric field by free carriers in multiple quantum wells grown on c-plane and r-plane sapphire substrates was achieved. Under such high excitation, luminescence efficiency and carrier lifetime of multiple quantum wells were shown to be determined by the substrate quality. (author)

Preparation and characterization of Tb3+ and Tb(sal)3.nH2O doped PC:PMMA blend

International Nuclear Information System (INIS)

Dwivedi, Y.; Singh, A.K.; Prakash, Rajiv; Rai, S.B.

2011-01-01

Tb doped polycarbonate:poly(methyl methacrylate) (Tb-PC:PMMA) blend was prepared with varying proportions of PC and PMMA. Thermal and spectroscopic properties of the doped polymer have been investigated employing Fourier Transform Infrared (FTIR) absorption and differential scanning calorimetric (DSC) techniques. PC:PMMA blend (with 10 wt% PC and 90 wt% PMMA) shows better miscibility. Optical properties of the dopant Tb 3+ ions have been investigated using UV-vis absorption and fluorescence excited by 355 nm radiation. It is seen that luminescence intensity of Tb 3+ ion depends on PC:PMMA ratio and on Tb 3+ ion concentration. Concentration quenching is seen for TbCl 3 .6H 2 O concentration larger than 4 wt%. Addition of salicylic acid to the polymer blend increases the luminescence from Tb 3+ ions. Luminescence decay curve analysis affirms the non-radiative energy transfer from salicylic acid to Tb 3+ ions, which is identified as the reason behind this enhancement. - Highlights: → Blend formation is confirmed at PC/90PMMA, using FTIR and DSC techniques. → Absorption and bandgap studies of blend and parent components were studied. → Optical properties of Tb and Tb(sal) 3 .nH 2 O complex have been studied in PC/PMMA blend. → Luminescence decay curves confirm non-radiative energy transfer from Sal to Tb 3+ ions.

Difference in luminescence sensitivity of coarse-grained quartz from deserts of northern China

International Nuclear Information System (INIS)

Zheng, C.X.; Zhou, L.P.; Qin, J.T.

2009-01-01

The luminescence sensitivity of coarse quartz extracted from desert sands in northern China was investigated. In general, the western deserts' samples are shown to be less sensitive than samples from the eastern deserts with respect to both OSL and the 110 deg. C TL peak. However, internal scatter among different aliquots of the same sample is observed for these two signals, which have already been normalized by weight. Laboratory dosing/bleach experiments indicate that earth surface processes, such as repeated burial and transportation can cause the sensitivity change and suggest that they may be responsible for the internal scatter. An intrinsic property of quartz was explored via the luminescence response to thermal activation to a maximum temperature of 700 deg. C. The thermal activation curves obtained with quartz from western and central deserts are similar, except one sample from Gurbantungut, which follows the pattern of eastern samples. The differences in quartz luminescence sensitivity exhibited by OSL/110 deg. C TL sensitivity and response to thermal activation are in accordance with the published results of geochemical studies.

Luminescent chiral ionic Ir(III) complexes: Synthesis and photophysical properties

Energy Technology Data Exchange (ETDEWEB)

Ricciardi, Loredana, E-mail: loredana.ricciardi@unical.it [CNR NANOTEC-Istituto di Nanotecnologia U.O.S. Cosenza, 87036 Arcavacata di Rende (CS) (Italy); La Deda, Massimo; Ionescu, Andreea; Godbert, Nicolas; Aiello, Iolinda; Ghedini, Mauro [MAT-INLAB (Laboratorio di Materiali Molecolari Inorganici), LASCAMM and CR INSTM, Unità INSTM della Calabria, Dipartimento di Chimica e Tecnologie Chimiche, Università della Calabria, 87036 Arcavacata di Rende (CS) (Italy); Fusè, Marco, E-mail: marco.fuse@unimi.it [Dipartimento di Scienze Farmaceutiche, Università di Milano, Via Golgi 19, 20133 Milano (Italy); Rimoldi, Isabella; Cesarotti, Edoardo [Dipartimento di Scienze Farmaceutiche, Università di Milano, Via Golgi 19, 20133 Milano (Italy)

2016-02-15

Three homologous series of luminescent octahedral ionic Ir(III) complexes (1–12) with a dual stereogenic center of general formula {sup Δ,Λ} {sup (R,S)}[(ppy){sub 2}Ir(R-campy)]X, where ppy=2-phenylpyridine, R-campy=2-methyl-5,6,7,8-tetrahydroquinolin-8-amine (Me-campy) or 8-amino-5,6,7,8-tetrahydroquinolines (H-campy) and as counterions X{sup −}=Cl{sup −} or CH{sub 3}COO{sup −} have been synthesized and characterized. The NMR characterization of each complex highlighted the diastereoisomeric purity and the absolute configuration has been confirmed by Electronic Circular Dichroism spectroscopy. The absorption and the luminescence properties of the compounds in solution and in solid state have been investigated by UV–vis, steady-state emission and time-correlated single-photon counting spectroscopy. The obtained results from the 12 compounds highlight the difficult to correlate photophysical properties in solution to the stereochemistry, while excited states decay studies of the solid state samples indicate a correlation between photophysics and packing mode which is affected by the different stereochemistry. - Highlights: • Luminescent chiral ionic Ir(III) complexes have been synthesized and characterized. • Presence in the same structure of two stereogenic centers. • Use of camphorsulfonate as resolving anion to obtain enantiomerically pure samples. • Stereoisomers produce aggregates with different emitting properties. • Lifetimes from solid samples show the presence of AIPE.

Positron-Induced Luminescence

Science.gov (United States)

Stenson, E. V.; Hergenhahn, U.; Stoneking, M. R.; Pedersen, T. Sunn

2018-04-01

We report on the observation that low-energy positrons incident on a phosphor screen produce significantly more luminescence than electrons do. For two different wide-band-gap semiconductor phosphors (ZnS:Ag and ZnO:Zn), we compare the luminescent response to a positron beam with the response to an electron beam. For both phosphors, the positron response is significantly brighter than the electron response, by a factor that depends strongly on incident energy (0-5 keV). Positrons with just a few tens of electron-volts of energy (for ZnS:Ag) or less (for ZnO:Zn) produce as much luminescence as is produced by electrons with several kilo-electron-volts. We attribute this effect to valence band holes and excited electrons produced by positron annihilation and subsequent Auger processes. These results demonstrate a valuable approach for addressing long-standing questions about luminescent materials.

Up conversion luminescence of Yb3+–Er3+ codoped CeO2 nanocrystals with imaging applications

International Nuclear Information System (INIS)

Cho, Jung-Hyun; Bass, Michael; Babu, Suresh; Dowding, Janet M.; Self, William T.; Seal, Sudipta

2012-01-01

The effects of Yb 3+ doping on up conversion in Yb 3+ –Er 3+ co-doped cerium oxide nanocrystals are reported. Green emission around 545 and 560 nm attributed to the 2 H 11/2 , 4 S 3/2 → 4 I 15/2 transitions and red emission around 660 and 680 nm due to 4 F 9/2 → 4 I 15/2 transitions under 975 nm excitation were studied at room temperature. Both green and red emission intensities increase as the Yb 3+ concentration increases from 0%. Emission strength starts to decrease after the Yb 3+ concentration exceeds a critical amount. The green emission strength peaks around 1% Yb 3+ concentration while the red emission strength peaks around 4%. An explanation of competition between different decay mechanisms is presented to account for the luminescence dependence on Yb 3+ concentration. Also, the application of up converting nanoparticles in biomedical imaging is demonstrated. - Highlights: ► Up conversion in Yb 3+ –Er 3+ co-doped cerium oxide nanocrystals. ► Different decay mechanisms determine luminescence efficiency. ► Up converting nanoparticles in biomedical imaging is demonstrated.

Luminescence from metals and insulators

International Nuclear Information System (INIS)

Crawford, O.H.

1985-01-01

The term luminescence is normally applied to light emission that is not explainable by the mechanisms discussed by the other speakers in this meeting. Specifically, it is not transition radiation, surface plasmon radiation, or bremsstrahlung. One normally thinks of luminescence as arising from one-electron transitions within a medium. This talk consists of an overview of luminescence from condensed matter under irradiation by either energetic particles or photons. The author begins with organic molecules, where luminescence is best understood, and then discusses inorganic insulators and metals. Finally, the dependence of yield upon projectile species and velocity is discussed, and predictions are made concerning the relative effectiveness of electrons, protons, and hydrogen atoms in exciting luminescence

Life-time resolved emission spectra in CdCl2 crystals

International Nuclear Information System (INIS)

Kawabata, S.; Nakagawa, H.; Kitaura, M.

2005-01-01

The emission spectrum of CdCl 2 is composed of ultraviolet (UV) and yellow (Y) bands peaking at 3.70 and 2.30 eV, respectively. In order to determine the initial states of the Y-luminescence, decay curves of the Y-emission were measured at 8K by varying emission energy in the range from 1.64 eV to 3.13 eV. The observed decay curves are composed of two or three exponential components. The values of lifetime for them were 900, 460 and 60 μs. The emission spectrum for each decay component, i.e., life-time resolved emission spectrum, was analyzed by the observed decay curves. The emission spectrum for the component of 460 μs lifetime exhibits a dominant band at 2.30 eV and a satellite band at 3.03 eV. The emission spectrum for the component of 60 μs lifetime is reproduced by the three Gaussian bands peaking at 2.21, 2.65 and 2.87 eV. For the component of 900 μs lifetime, only a single band appears at 1.73 eV. The origin of the emission bands in life-time resolved emission spectra is briefly discussed, and the initial states of Y-luminescence are explained by the excited states of a [Cd 2+ Cl - 6 ] 4- complex molecular ion. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Study of the absorption and energy transfer processes in inorganic luminescent materials in the UV and VUV region; Etude des processus d`absorption et de transfert d`energie au sein de materiaux inorganiques luminescents dans le domaine UV et VUV

Energy Technology Data Exchange (ETDEWEB)

Mayolet, A

1995-11-29

In order to find a green emitting phosphor showing high quantum efficiency and a short decay time which can be used in the color Plasma Display Panels developed by Thomson-TTE-TIV company, a VUV spectrophotometer built at IPN Orsay, using the synchrotron radiation from the SUPER-ACO storage ring as an excitation source, allow us the simultaneous recording of the luminescence excitation and diffuse reflectivity spectra of the inorganic compounds in the UV-VUV range. In addition, this experimental set-up enable us to determine the luminescence quantum efficiency of phosphors in the whole energy range of investigation. The chemical synthesis of rare-earth ortho-- and metaborate and rare-earth ortho- and metaphosphate doped with trivalent lanthanide ions cerium, praseodymium, europium and terbium have been made. The energy variation of the thresholds of the luminescence excitation mechanisms in function of the nature and the structure of the host matrix is discussed. We have determined the influence of the nephelauxetic effect and the crystal field intensity on the energy of the f-d inter-configuration transitions. The variation of the luminescence quantum efficiency of the dopant ion is interpreted through the `impurity bound exciton` model. The systematic comparison of the cerium and terbium trivalent ions spectroscopic properties in the Y(AG)G host lattice series stands to reason that the self-ionized state of the luminescent center plays an important role in the rate of the non radiative relaxation. It is the redox power of the host matrix which imposes to the luminescent center, the energy of this state. (author) 134 refs.

Thermally and optically stimulated luminescence of new ZnO nano phosphors exposed to beta radiation

International Nuclear Information System (INIS)

Cruz V, C.; Burruel I, S.E.; Grijalva M, H.; Chernov, V.; Bernal, R.

2006-01-01

In this work, we report the thermoluminescence (TL) and the optically stimulated luminescence (OSL) of ZnO nano phosphors obtained by thermal annealing of ZnS powders synthesized by precipitation in a chemical bath deposition reaction. To obtain nanocrystalline ZnO, ZnS pellet-shaped samples were subjected to a sintering process at 700 C during 24 under air atmosphere. Some samples were exposed to beta particles in the 0.15-10.15 kGy dose range and the integrated thermoluminescence as a function of dose increased as dose increased, with no saturation clue for the tested doses. Computerized glow-curve deconvolution of the experimental TL curves in individual peaks revealed a second order kinetics. In order to test the BOSL (Blue Optically Stimulated Luminescence) response, samples were beta irradiated with doses up to 600 Gy, showing an increasing OSL intensity as dose increases. From the experimental results that we have obtained, we conclude that the new ZnO phosphors under investigation are good candidates to be used as dosimetric materials. (Author)

Performance of a novel multiple-signal luminescence sediment tracing method

Science.gov (United States)

Reimann, Tony

2014-05-01

Optically Stimulated Luminescence (OSL) is commonly used for dating sediments. Luminescence signals build up due to exposure of mineral grains to natural ionizing radiation, and are reset when these grains are exposed to (sun)light during sediment transport and deposition. Generally, luminescence signals can be read in two ways, potentially providing information on the burial history (dating) or the transport history (sediment tracing) of mineral grains. In this study we use a novel luminescence measurement procedure (Reimann et al., submitted) that simultaneously monitors six different luminescence signals from the same sub-sample (aliquot) to infer the transport history of sand grains. Daylight exposure experiments reveal that each of these six signals resets (bleaches) at a different rate, thus allowing to trace the bleaching history of the sediment in six different observation windows. To test the feasibility of luminescence sediment tracing in shallow-marine coastal settings we took eight sediment samples from the pilot mega-nourishment Zandmotor in Kijkduin (South-Holland). This site provides relatively controlled conditions as the morphological evolution of this nourishment is densely monitored (Stive et al., 2013). After sampling the original nourishment source we took samples along the seaward facing contour of the spit that was formed from August 2011 (start of nourishment) to June 2012 (sampling). It is presumed that these samples originate from the source and were transported and deposited within the first year after construction. The measured luminescence of a sediment sample was interpolated onto the daylight bleaching curve of each signal to assign the Equivalent Exposure Time (EET) to a sample. The EET is a quantitative measure of the full daylight equivalent a sample was exposed to during sediment transport, i.e. the higher the EET the longer the sample has been transported or the more efficient it has been exposed to day-light during sediment

Study of the absorption and energy transfer processes in inorganic luminescent materials in the UV and VUV region

International Nuclear Information System (INIS)

Mayolet, A.

1995-01-01

In order to find a green emitting phosphor showing high quantum efficiency and a short decay time which can be used in the color Plasma Display Panels developed by Thomson-TTE-TIV company, a VUV spectrophotometer built at IPN Orsay, using the synchrotron radiation from the SUPER-ACO storage ring as an excitation source, allow us the simultaneous recording of the luminescence excitation and diffuse reflectivity spectra of the inorganic compounds in the UV-VUV range. In addition, this experimental set-up enable us to determine the luminescence quantum efficiency of phosphors in the whole energy range of investigation. The chemical synthesis of rare-earth ortho-- and metaborate and rare-earth ortho- and metaphosphate doped with trivalent lanthanide ions cerium, praseodymium, europium and terbium have been made. The energy variation of the thresholds of the luminescence excitation mechanisms in function of the nature and the structure of the host matrix is discussed. We have determined the influence of the nephelauxetic effect and the crystal field intensity on the energy of the f-d inter-configuration transitions. The variation of the luminescence quantum efficiency of the dopant ion is interpreted through the 'impurity bound exciton' model. The systematic comparison of the cerium and terbium trivalent ions spectroscopic properties in the Y(AG)G host lattice series stands to reason that the self-ionized state of the luminescent center plays an important role in the rate of the non radiative relaxation. It is the redox power of the host matrix which imposes to the luminescent center, the energy of this state. (author)

Resonance-shifting luminescent solar concentrators

Energy Technology Data Exchange (ETDEWEB)

Giebink, Noel Christopher; Wiederrecht, Gary P.; Wasielewski, Michael R.

2018-01-23

An optical system and method to overcome luminescent solar concentrator inefficiencies by resonance-shifting, in which sharply directed emission from a bi-layer cavity into a glass substrate returns to interact with the cavity off-resonance at each subsequent reflection, significantly reducing reabsorption loss en route to the edges. In one embodiment, the system comprises a luminescent solar concentrator comprising a transparent substrate, a luminescent film having a variable thickness; and a low refractive index layer disposed between the transparent substrate and the luminescent film.

Luminescence of UO2+sub(2(aq)) + FU+sub(2(aq)) and evidence for the formation of a new inorganic radiative exciplex in aqueous solution

International Nuclear Information System (INIS)

Deschaux, M.; Marcantonatos, M.D.

1981-01-01

Steady-state and time-resolved luminescence measurements, as well as decays of excited UO 2 2+ + FUO 2 + in aqueous solution, show the formation of a radiative exciplex, resulting from the interaction of *FUO 2 H + with UO 2 2+ , similarly to the *U 2 O 4 H 4+ exciplex already reported. Lifetimes and evaluations of the luminescence yields of the *UO 2 2+ , *FUO 2 + and of the exciplex of probable *(O(F)UOHOUO) 3+ composition, are given. The overall heat of the exciplex formation is estimated. (author)

Feldspar, Infrared Stimulated Luminescence

DEFF Research Database (Denmark)

Jain, Mayank

2014-01-01

This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars.......This entry primarily concerns the characteristics and the origins of infrared-stimulated luminescence in feldspars....

Evidence against solar influence on nuclear decay constants

Directory of Open Access Journals (Sweden)

S. Pommé

2016-10-01

Full Text Available The hypothesis that proximity to the Sun causes variation of decay constants at permille level has been tested and disproved. Repeated activity measurements of mono-radionuclide sources were performed over periods from 200 days up to four decades at 14 laboratories across the globe. Residuals from the exponential nuclear decay curves were inspected for annual oscillations. Systematic deviations from a purely exponential decay curve differ from one data set to another and are attributable to instabilities in the instrumentation and measurement conditions. The most stable activity measurements of alpha, beta-minus, electron capture, and beta-plus decaying sources set an upper limit of 0.0006% to 0.008% to the amplitude of annual oscillations in the decay rate. Oscillations in phase with Earth's orbital distance to the Sun could not be observed within a 10−6 to 10−5 range of precision. There are also no apparent modulations over periods of weeks or months. Consequently, there is no indication of a natural impediment against sub-permille accuracy in half-life determinations, renormalisation of activity to a distant reference date, application of nuclear dating for archaeology, geo- and cosmochronology, nor in establishing the SI unit becquerel and seeking international equivalence of activity standards.

X-ray excited optical luminescence of polynuclear aromatic hydrocarbons

Energy Technology Data Exchange (ETDEWEB)

Oestreich, G.J.

1979-05-01

X-ray excited optical luminescence (XEOL) coupled with time resolved spectroscopy was employed to analyze polynuclear aromatic hydrocarbons (PAH) in n-alkane solvents at 10 K. A pulsed XEOL system which was designed around minicomputer control of a medical x-ray unit was developed. Computer software which generated variable width x-ray pulses, monitored timing reference pulses, controlled data acquisition, and analyzed data was written. Phosphorescence decay constants of several PAHs were determined. Synthetic mixtures of zone refined PAHs were prepared and time resolved with the pulsed XEOL technique. Analytical results obtained from the five component mixtures of PAHs at the part per million level were tabulated. Systematic improvements and further development of the pulsed XEOL method were considered.

Time-resolved measurements of luminescence

Energy Technology Data Exchange (ETDEWEB)

Collier, Bradley B. [Department of Biomedical Engineering, 408 Mechanical Engineering Office Building, Spence Street, Texas A and M University, College Station, TX 77843 (United States); McShane, Michael J., E-mail: mcshane@tamu.edu [Department of Biomedical Engineering, 408 Mechanical Engineering Office Building, Spence Street, Texas A and M University, College Station, TX 77843 (United States); Materials Science and Engineering Program, 408 Mechanical Engineering Office Building, Spence Street, Texas A and M University, College Station, TX 77843 (United States)

2013-12-15

Luminescence sensing and imaging has become more widespread in recent years in a variety of industries including the biomedical and environmental fields. Measurements of luminescence lifetime hold inherent advantages over intensity-based response measurements, and advances in both technology and methods have enabled their use in a broader spectrum of applications including real-time medical diagnostics. This review will focus on recent advances in analytical methods, particularly calculation techniques, including time- and frequency-domain lifetime approaches as well as other time-resolved measurements of luminescence. -- Highlights: • Developments in technology have led to widespread use of luminescence lifetime. • Growing interest for sensing and imaging applications. • Recent advances in approaches to lifetime calculations are reviewed. • Advantages and disadvantages of various methods are weighed. • Other methods for measurement of luminescence lifetime also described.

Time-resolved measurements of luminescence

International Nuclear Information System (INIS)

Collier, Bradley B.; McShane, Michael J.

2013-01-01

Luminescence sensing and imaging has become more widespread in recent years in a variety of industries including the biomedical and environmental fields. Measurements of luminescence lifetime hold inherent advantages over intensity-based response measurements, and advances in both technology and methods have enabled their use in a broader spectrum of applications including real-time medical diagnostics. This review will focus on recent advances in analytical methods, particularly calculation techniques, including time- and frequency-domain lifetime approaches as well as other time-resolved measurements of luminescence. -- Highlights: • Developments in technology have led to widespread use of luminescence lifetime. • Growing interest for sensing and imaging applications. • Recent advances in approaches to lifetime calculations are reviewed. • Advantages and disadvantages of various methods are weighed. • Other methods for measurement of luminescence lifetime also described

Methodology of measurement of thermal neutron time decay constant in Canberra 35+ MCA system

International Nuclear Information System (INIS)

Drozdowicz, K.; Gabanska, B.; Igielski, A.; Krynicka, E.; Woznicka, U.

1993-01-01

A method of the thermal neutron time decay constant measurement in small bounded media is presented. A 14 MeV pulsed neutron generator is the neutron source. The system of recording of a die-away curve of thermal neutrons consists of a 3 He detector and of a multichannel time analyzer based on analyzer Canberra 35+ with multi scaler module MCS 7880 (microsecond range). Optimum parameters for the measuring system are considered. Experimental verification of a dead time of the instrumentation system is made and a count-loss correction is incorporated into the data treatment. An attention is paid to evaluate with a high accuracy the fundamental mode decay constant of the registered decaying curve. A new procedure of the determination of the decay constant by a multiple recording of the die-away curve is presented and results of test measurements are shown. (author). 11 refs, 12 figs, 4 tabs

Methodology of measurement of thermal neutron time decay constant in Canberra 35+ MCA system

Energy Technology Data Exchange (ETDEWEB)

Drozdowicz, K; Gabanska, B; Igielski, A; Krynicka, E; Woznicka, U [Institute of Nuclear Physics, Cracow (Poland)

1994-12-31

A method of the thermal neutron time decay constant measurement in small bounded media is presented. A 14 MeV pulsed neutron generator is the neutron source. The system of recording of a die-away curve of thermal neutrons consists of a {sup 3}He detector and of a multichannel time analyzer based on analyzer Canberra 35+ with multi scaler module MCS 7880 (microsecond range). Optimum parameters for the measuring system are considered. Experimental verification of a dead time of the instrumentation system is made and a count-loss correction is incorporated into the data treatment. An attention is paid to evaluate with a high accuracy the fundamental mode decay constant of the registered decaying curve. A new procedure of the determination of the decay constant by a multiple recording of the die-away curve is presented and results of test measurements are shown. (author). 11 refs, 12 figs, 4 tabs.

Methodology of measurement of thermal neutron time decay constant in Canberra 35+ MCA system

Energy Technology Data Exchange (ETDEWEB)

Drozdowicz, K.; Gabanska, B.; Igielski, A.; Krynicka, E.; Woznicka, U. [Institute of Nuclear Physics, Cracow (Poland)

1993-12-31

A method of the thermal neutron time decay constant measurement in small bounded media is presented. A 14 MeV pulsed neutron generator is the neutron source. The system of recording of a die-away curve of thermal neutrons consists of a {sup 3}He detector and of a multichannel time analyzer based on analyzer Canberra 35+ with multi scaler module MCS 7880 (microsecond range). Optimum parameters for the measuring system are considered. Experimental verification of a dead time of the instrumentation system is made and a count-loss correction is incorporated into the data treatment. An attention is paid to evaluate with a high accuracy the fundamental mode decay constant of the registered decaying curve. A new procedure of the determination of the decay constant by a multiple recording of the die-away curve is presented and results of test measurements are shown. (author). 11 refs, 12 figs, 4 tabs.

Facile one-step hydrothermal synthesis and luminescence properties of Eu{sup 3+}-doped NaGd(WO{sub 4}){sub 2} nanophosphors

Energy Technology Data Exchange (ETDEWEB)

Jiang, Zehan; Cai, Peiqing; Chen, Cuili; Pu, Xipeng; Kim, Sun Il, E-mail: sikim@pknu.ac.kr; Jin Seo, Hyo, E-mail: hjseo@pknu.ac.kr

2017-06-01

Eu{sup 3+}-doped NaGd(WO{sub 4}){sub 2} nanophosphors were synthesized via a facile one-step hydrothermal method without any surfactants or a further heat treatment. X-ray powder diffraction (XRD), scanning electron microscope (SEM), fourier transform infrared spectroscopy (FT-IR), the photoluminescence (PL) excitation and emission spectra, and decay curves were used to characterize NaGd(WO{sub 4}){sub 2}:Eu{sup 3+} phosphors. The results show that the Eu{sup 3+}-concentration has little influence on the structure and morphology of the as-synthesized samples. However, pH value plays a vital role on the structure and morphology of NaGd(WO{sub 4}){sub 2}. The well-crystallized sheet-like NaGd(WO{sub 4}){sub 2} phosphors can be obtained only at pH = 5–7. On the basis of the time-dependent synthesis, a possible growth mechanism of sheet-like architectures is proposed. The luminescence properties of NaGd{sub 1-x}Eu{sub x}(WO{sub 4}){sub 2} (0 ≤ x ≤ 1) are investigated. It is found that the charge transfer band of Eu{sup 3+} shifts to lower energy and broadens with increasing the Eu{sup 3+}-concentration. - Highlights: • NaGd(WO{sub 4}){sub 2}:Eu{sup 3+} nanosheets were synthesized by facile one-step hydrothermal method. • Luminescence properties of NaGd(WO{sub 4}){sub 2}:Eu{sup 3+} phosphor were firstly reported. • The CT band of Eu{sup 3+} depends strongly on Eu{sup 3+}-concentrations.

Structural and luminescence properties of Gd{sub 2}Si{sub 2}O{sub 7}:Ce prepared by solution combustion followed by heat treatment

Energy Technology Data Exchange (ETDEWEB)

Shinde, Seema; Pitale, Shreyas; Singh, S.G.; Ghosh, M.; Tiwari, B.; Sen, S.; Gadkari, S.C., E-mail: gadkari@barc.gov.in; Gupta, S.K.

2015-05-05

Highlights: • Synthesis of triclinic and orthorhombic phases of Gd{sub 2}Si{sub 2}O{sub 7}:Ce by a two step process. • Method involves solution combustion followed by a post heat treatment. • Ce concentration is found to affect the orthorhombic phase formation temperature. • First time reporting a double exponential decay in nano sized Gd{sub 2}Si{sub 2}O{sub 7}:Ce. - Abstract: A method comprising solution combustion followed by a heat treatment has been employed to synthesize cerium doped gadolinium pyrosilicate (Gd{sub 2}Si{sub 2}O{sub 7}:Ce, or GPS:Ce) compounds. The powder obtained after the combustion was annealed at 1200 °C for 4 h and 1600 °C for 3 h to synthesize triclinic and orthorhombic phases of the GPS, respectively. Structural and morphological characterizations of the synthesized compounds were carried out using X-ray diffraction and electron microscopy (SEM, TEM) techniques. A change in the enthalpy was observed in the differential thermal analysis data as a consequence of triclinic to orthorhombic phase transition in the GPS. Luminescence spectra and fluorescence decay time were measured at room temperature to characterize emission centers created in GPS compounds doped with trivalent rare earth ion (Ce{sup 3+}). The triclinic GPS:Ce phase exhibited photoluminescence peaks at 379 nm and 410 nm while for the orthorhombic phase emissions at 353 nm and 380 nm were observed. A multi-component exponential decay pattern of the luminescence is observed for both the GPS:Ce phases. In addition, samples of the orthorhombic GPS:Ce were found to exhibit X-ray excited luminescence (XEL)

Advantages and disadvantages of luminescence dosimetry

Energy Technology Data Exchange (ETDEWEB)

Olko, Pawel, E-mail: Pawel.Olko@ifj.edu.p [Institute of Nuclear Physics Polish Academy of Science (IFJ PAN), Krakow (Poland)

2010-03-15

Owing to their excellent dosimetric properties, luminescence detectors of ionizing radiation are now extensively applied in individual dosimetry services. The most frequently used personal dosemeters are based on Optically Stimulated Luminescence (OSL), radiophotoluminescence (RPL) or thermoluminescence (TL). Luminescence detectors have also found several applications in clinical dosimetry, especially around new radiation modalities in radiotherapy, such as Intensity Modulated Radiotherapy (IMRT) or ion beam radiotherapy. Requirements of luminescence detectors applied in individual and clinical dosimetry and some recent developments in luminescence of detectors and techniques leading to significant improvements of the functionality and accuracy of dosimetry systems are reviewed and discussed.

Soft X-ray excited optical luminescence from functional organic materials

Energy Technology Data Exchange (ETDEWEB)

Sham, T.K., E-mail: tsham@uwo.ca

2015-10-01

Highlights: • Many functional organic materials convert X-ray energy into visible light. • The X-ray induced luminescence (XEOL) across an absorption edge can be site and excitation channel specific. • XEOL is composition, morphology, size and crystallinity dependent. • XEOL using the time structure of a synchrotron can reveal the decay and energy transfer dynamics of the sample. • The combined use of XEOL and XAS in the analysis of functional organic materials is illustrated. - Abstract: This brief report reviews some of the recent findings in the study of synchrotron based X-ray excited optical luminescence (XEOL) from representative organic light emitting device (OLED) and related functional organic materials. The systems of interest include Alq{sub 3}, aluminium tris(8-hydroxylquinoline); Ru(bipy){sub 3}{sup 2+}, tris-(2,2-bipyridine) ruthenium(II); Ir(bpy){sub 3}, tris(2-phenyl-bipyridine)iridium; PVK (poly(N-vinylcarbazole)) and [Au{sub 2}(dppe)(bipy)]{sup 2+}, a Au(I) polymer containing 1,2-bis(diphenylphosphino)ethane and the 4,40-bipyridyl ligands, as well as TBPe (2,5,8,11-tetra-tert-butylperylene) polyhedral crystals and fluorescein isothiocyanate (FITC) and FITC-labelled proteins. It is shown that tunable and pulsed X-rays from synchrotron light sources enable the detailed tracking of the optical properties of organic functional materials by monitoring the luminescence in both the energy and time domain as the excitation energy is scanned across an element-specific absorption edge. The use of XEOL and X-ray absorption spectroscopy (XAS) in materials analysis is illustrated.

Influence of lead-related centers on luminescence of Ce3+ and Pr3+ centers in single crystalline films of aluminium perovskites and garnets

International Nuclear Information System (INIS)

Babin, V.; Gorbenko, V.; Krasnikov, A.; Makhov, A.; Nikl, M.; Zazubovich, S.; Zorenko, Yu.

2010-01-01

Luminescence characteristics of Ce 3+ - and Pr 3+ -doped aluminium perovskite (LuAlO 3 , YAlO 3 ) and garnet (Lu 3 Al 5 O 12 , Y 3 Al 5 O 12 ) single crystalline films, prepared by the liquid phase epitaxy method with the use of the PbO-based flux, were investigated by the time-resolved spectroscopy methods in the 80-300 K temperature range. The influence of various lead-related centers on the characteristics of the Ce 3+ - and Pr 3+ -related luminescence centers was studied. It was found that the presence of lead-related centers in the single crystalline films results in a decrease of the quantum efficiency and appearance of undesirable slow components in the luminescence decay kinetics. The possibilities of improving the scintillation characteristics of the single crystalline films were considered.

Luminescence and scintillation properties of YAG:Ce single crystal and optical ceramics

CERN Document Server

Mihóková, E; Mareš, J A; Beitlerová, A; Vedda, A; Nejezchleb, K; Blažek, K; D’Ambrosio, C

2007-01-01

We use various techniques to study optical and scintillation properties of Ce-doped yttrium aluminum garnet, Y3Al5O12 (YAG:Ce), in the form of a high-quality industrial single crystal. This was compared to optical ceramics prepared from YAG:Ce nanopowders. We present experimental data in the areas of optical absorption, radioluminescence, scintillation decay, photoelectron yield, thermally stimulated luminescence and radiation-induced absorption. The results point to an interesting feature—the absence of antisite (YAl, i.e. Y at the Al site) defects in optical ceramics. The scintillation decay of the ceramics is faster than that of the single crystal, but its photoelectron yield (measured with 1 μs integration time) is about 30–40% lower. Apart from the photoelectron yield value the YAG:Ce optical ceramic is fully comparable to a high quality industrial YAG:Ce single crystal and can become a competitive scintillator material.

Enhanced UV luminescence from InAlN quantum well structures using two temperature growth

International Nuclear Information System (INIS)

Zubialevich, Vitaly Z.; Sadler, Thomas C.; Dinh, Duc V.; Alam, Shahab N.; Li, Haoning; Pampili, Pietro; Parbrook, Peter J.

2014-01-01

InAlN/AlGaN multiple quantum wells (MQWs) emitting between 300 and 350 nm have been prepared by metalorganic chemical vapor deposition on planar AlN templates. To obtain strong room temperature luminescence from InAlN QWs a two temperature approach was required. The intensity decayed weakly as the temperature was increased to 300 K, with ratios I PL (300 K)/I PL (T) max up to 70%. This high apparent internal quantum efficiency is attributed to the exceptionally strong carrier localization in this material, which is also manifested by a high Stokes shift (0.52 eV) of the luminescence. Based on these results InAlN is proposed as a robust alternative to AlGaN for ultraviolet emitting devices. - Highlights: • InAlN quantum wells with AlGaN barriers emitting in near UV successfully grown using quasi-2T approach. • 1 nm AlGaN capping of InAlN quantum wells used to avoid In desorption during temperature ramp to barrier growth conditions. • Strong, thermally resilient luminescence obtained as a result of growth optimization. • Promise of InAlN as an alternative active region for UV emitters demonstrated

Relative level populations in S VI after beam-foil excitation, obtained from ANDC analyses of measured decay curves

International Nuclear Information System (INIS)

Engstroem, L.

1983-01-01

This paper reports the relative population of the levels 3p, 3d, 4d, 5d, 4f, 5g, 6g, 6h, 7h, 7i, 8i and 8k in Na-like sulfur, S VI, after beam-foil excitation at an energy of 3 MeV. For the first time the ANDC technique has been used to obtain the relative efficiency calibration of the detection system at discrete points in the wavelength interval 400-5000 A, from the analyses of measured decay curves. The advantages and limitations of this method are discussed. The populations obtained with this new technique are compared to previous measurements in multiply ionized atoms. The preferential population of the 3p and 3d levels observed in other Na-like ions is now accurately established. For the higher lying levels an almost constant population is observed. (Auth.)

Luminescence and structure of manganese(II) halogenides. Pt. 1

International Nuclear Information System (INIS)

Oelkrug, D.; Kempny, W.

1976-01-01

The luminescence decay times tau and luminescence intensities I of the mixed crystals Mnsub(x)Cdsub(1-x)Hal 2 (Hal = Bl, Br, J; x 6 -octahedra and of some compounds A 2 MnHal 4 (A = large cation) with unlinked MnHal 4 -tetrahedra were investigated between 4.2 K and 295 K. In Osub(h)-coordinated compounds tau decreases with increasing temperature, most strongly in the iodide namely by a factor of five. On the other hand I correspondingly increases to the same extent so that in all cases I x tau = const. That justifies the assumption of quantum yields independent of temperature with the ideal value of one. In Tsub(d)-coordinated compounds tau and I taken as such are constant in the whole temperature range. The Osub(h) - Tsub(d) contrast in tau and I is attributed to oscillator strengths either dependent on temperature or constant. In the case of MnHal 6 coordination the dependency on temperature may be expressed by the function ctgh(hνc/2kT), (νsub(J) = 80, νsub(Br) = 140, νsub(Cl) = 190 cm -1 ), νsup(Hal) very well corresponding with the mean value of the odd optical k = 0 phonons in the CdHal 2 lattice. (orig.) [de

Scintillation and optical properties of Sn-doped Ga2O3 single crystals

Science.gov (United States)

Usui, Yuki; Nakauchi, Daisuke; Kawano, Naoki; Okada, Go; Kawaguchi, Noriaki; Yanagida, Takayuki

2018-06-01

Sn-doped Ga2O3 single crystals were synthesized by the Floating Zone (FZ) method. In photoluminescence (PL) under the excitation wavelength of 280 nm, we observed two types of luminescence: (1) defect luminescence due to recombination of the donor/acceptor pairs which appears at 430 nm and (2) the nsnp-ns2 transitions of Sn2+ which appear at 530 nm. The PL and scintillation decay time curves of the Sn-doped samples were approximated by a sum of exponential decay functions. The faster two components were ascribed to the defect luminescence, and the slowest component was owing to the nsnp-ns2 transitions. In the pulse height spectrum measurements under 241Am α-rays irradiation, all the Sn-doped Ga2O3 samples were confirmed to show a full energy absorption peak but the undoped one. Among the present samples, the 1% Sn-doped sample exhibited the highest scintillation light yield (1,500 ± 150 ph/5.5 MeV-α).

Magnetic and luminescent hybrid nanomaterial based on Fe{sub 3}O{sub 4} nanocrystals and GdPO{sub 4}:Eu{sup 3+} nanoneedles

Energy Technology Data Exchange (ETDEWEB)

Runowski, Marcin; Grzyb, Tomasz; Lis, Stefan, E-mail: blis@amu.edu.pl [Adam Mickiewicz University, Department of Rare Earths, Faculty of Chemistry (Poland)

2012-10-15

A bifunctional hybrid nanomaterial, which can show magnetic and luminescent properties, was obtained. A magnetic phase was synthesized as a core/shell type composite. Nanocrystalline magnetite, Fe{sub 3}O{sub 4} was used as the core and was encapsulated in a silica shell. The luminescent phase was GdPO{sub 4} doped with Eu{sup 3+} ions, as the emitter. The investigated materials were synthesized using a coprecipitation method. Encapsulated Fe{sub 3}O{sub 4} was 'trapped' in a nano-scaffold composed of GdPO{sub 4} crystalline nanoneedles. When an external magnetic field was applied, this hybrid composite was attracted in one direction. Also, the luminescent phase can move simultaneously with magnetite due to a 'trapping' effect. The structure and morphology of the obtained nanocomposites were examined with the use of transmission electron microscopy and X-ray powder diffraction. Spectroscopic properties of the Eu{sup 3+}-doped nanomaterials were studied by measuring their excitation and emission spectra as well as their luminescence decay times.Graphical Abstract.

What is the origin of concentration quenching of Cu"+ luminescence in glass?

International Nuclear Information System (INIS)

Jiménez, José A.

2016-01-01

Monovalent copper-doped luminescent glasses are attractive materials for white light-emitting devices, photonic waveguides, and solar spectral conversion in photovoltaic cells. However, the occurrence of concentration quenching in such is not fully understood at present. In this work, calcium-phosphate glasses with high concentrations of luminescent Cu"+ ions have been prepared by a simple melt-quench method via CuO and SnO co-doping. The aim is to elucidate the origin of concentration quenching of Cu"+ light emission. A spectroscopic characterization was carried out by optical absorption and photoluminescence (PL) spectroscopy including emission decay dynamics. The concentrations of both CuO and SnO dopants were varied as 5, 10 and 15 mol%. Monovalent copper content is estimated in the CuO/SnO-containing glasses following the assessment of the concentration dependence of Cu"2"+ absorption in the visible for CuO singly-doped glasses. Contrary to the conventionally acknowledged direct Cu"+→Cu"2"+ transfer, the data supports a Cu"+–Cu"+ energy migration channel at the origin of the PL quenching.

Luminescence properties of undoped CsCaCl3 and CsSrCl3 crystalline scintillators

International Nuclear Information System (INIS)

Fujimoto, Yutaka; Saeki, Keiichiro; Koshimizu, Masanori; Asai, Keisuke; Yanagida, Takayuki

2015-01-01

Intrinsic luminescence properties of undoped CsCaCl 3 and CsSrCl 3 crystalline scintillators were studied. The crystal samples were grown by a vertical Bridgman method. Photoluminescence spectra of the crystals showed Auger-free luminescence (AFL) at 310 nm and self-trapped emission (STE) at 400 nm for CsCaCl 3 and 465 nm for CsSrCl 3 , when vacuum ultraviolet (VUV) light at 84 nm and 160 nm excited the crystals. X-ray excited radioluminescence spectra of the crystals showed some emission bands in the 280-600 nm wavelength range, which are owing to AFL, STE, and other origins such as lattice defects and impurities. Scintillation light yield was 400-300 ph/MeV, and the principal scintillation decay time about 2.5 ns and 12 ns for CsCaCl 3 and 1.8 ns and 13 ns for CsSrCl 3 . (author)

Bound states in curved quantum waveguides

International Nuclear Information System (INIS)

Exner, P.; Seba, P.

1987-01-01

We study free quantum particle living on a curved planar strip Ω of a fixed width d with Dirichlet boundary conditions. It can serve as a model for electrons in thin films on a cylindrical-type substrate, or in a curved quantum wire. Assuming that the boundary of Ω is infinitely smooth and its curvature decays fast enough at infinity, we prove that a bound state with energy below the first transversal mode exists for all sufficiently small d. A lower bound on the critical width is obtained using the Birman-Schwinger technique. (orig.)

Luminescence properties of Yb:Nd:Tm:KY3F10 nanophosphor and thermal treatment effects

International Nuclear Information System (INIS)

Gomes, Laércio; Linhares, Horácio Marconi da Silva M.D.; Ichikawa, Rodrigo Uchida; Martinez, Luis Gallego; Ranieri, Izilda Marcia

2015-01-01

In this work, we present the spectroscopic properties of KY 3 F 10 (KY3F) nanocrystals activated with thulium and codoped with ytterbium and neodymium ions. The most important processes that lead to the thulium upconversion emissions in the blue region were identified. A time-resolved luminescence spectroscopy technique was employed to measure the luminescence decays and to determine the most important mechanisms involved in the upconversion process that populates 1 G 4 (Tm 3+ ) excited states. Analysis of the energy-transfer processes dynamics using selective pulsed-laser excitations in Yb:Nd:Tm, Nd:KY3F nanocrystals shows that the direct energy transfer from Nd 3+ to Tm 3+ ions is the mechanism responsible for the 78% of the blue upconversion luminescence in the Yb:Nd:Tm:KY3F when compared with the Yb:Nd:Tm:KY3F bulk crystal for an laser excitation at 802 nm. An investigation of the 1 G 4 level luminescence kinetic of Tm 3+ in Yb/Nd/Tm system revealed that the luminescence efficiency ( 1 G 4 ) starts with a very low value (0.38%) for the synthesized nanocrystal (as grown) and strongly increases to 97% after thermal treatment at 550 °C for 6 h under argon flow. As a consequence of the thermal treatment at T=550 °C, the contributions of the (Nd×Tm) (Up 1 ) and (Nd×Yb×Tm) (Up 2 ) upconversion processes to the 1 G 4 luminescence are 33% (Up 1 ) and 67% for Up 2 . Up 2 process represented by Nd 3+ ( 4 F 3/2 )→Yb 3+ ( 2 F 7/2 ) followed by Yb 3+ ( 2 F 5/2 )→Tm ( 3 H 4 )→Tm 3+ ( 1 G 4 ) was previously reported as the main mechanism to produce the blue luminescence in Yb:Nd:Tm:YLiF 4 and KY 3 F 10 bulk crystals. Results of X-ray diffraction analysis of nanopowder using the Rietveld method reveled that crystallite sizes remain unchanged (12–14 nm) after thermal treatments with T≤400 °C, while the 1 G 4 luminescence efficiency strongly increases from 0.38% (T=25 °C) to 12% (T=400 °C). Results shown that the Nd 3+ ions distribution has a concentration

Seismic Moment and Recurrence using Luminescence Dating Techniques: Characterizing brittle fault zone materials suitable for luminescence dating

Science.gov (United States)

Tsakalos, E.; Lin, A.; Bassiakos, Y.; Kazantzaki, M.; Filippaki, E.

2017-12-01

During a seismic-geodynamic process, frictional heating and pressure are generated on sediments fragments resulting in deformation and alteration of minerals contained in them. The luminescence signal enclosed in minerals crystal lattice can be affected and even zeroed during such an event. This has been breakthrough in geochronological studies as it could be utilized as a chronometer for the previous seismic activity of a tectonically active area. Although the employment of luminescence dating has in some cases been successfully described, a comprehensive study outlining and defining protocols for routine luminescence dating applied to neotectonic studies has not been forthcoming. This study is the experimental investigation, recording and parameterization of the effects of tectonic phenomena on minerals luminescence signal and the development of detailed protocols for the standardization of the luminescence methodology for directly dating deformed geological formations, so that the long-term temporal behaviour of seismically active faults could be reasonably understood and modeled. This will be achieved by: a) identifying and proposing brittle fault zone materials suitable for luminescence dating using petrological, mineralogical and chemical analyses and b) investigating the "zeroing" potential of the luminescence signal of minerals contained in fault zone materials by employing experimental simulations of tectonic processes in the laboratory, combined with luminescence measurements on samples collected from real fault zones. For this to be achieved, a number of samples collected from four faults of four different geographical regions will be used. This preliminary-first step of the study presents the microstructural, and mineralogical analyses for the characterization of brittle fault zone materials that contain suitable minerals for luminescence dating (e.g., quartz and feldspar). The results showed that the collected samples are seismically deformed fault

Test of nonexponential deviations from decay curve of 52V using continuous kinetic function method

International Nuclear Information System (INIS)

Tran Dai Nghiep; Vu Hoang Lam; Vo Tuong Hanh; Do Nguyet Minh; Nguyen Ngoc Son

1993-01-01

The present work is aimed at a formulation of an experimental approach to search the proposed description of an attempt to test them in case of 52 V. Some theoretical description of decay processes are formulated in clarified forms. The continuous kinetic function (CKF) method is used for analysis of experimental data and CKF for purely exponential case is considered as a standard for comparison between theoretical and experimental data. The degree of agreement is defined by the factor of goodness. Typical deviations of oscillation behavior of 52 V decay were observed in a wide range of time. The proposed deviation related to interaction between decay products and environment is research. A complex type of decay is discussed. (author). 10 refs, 2 tabs, 5 figs

Luminescence characteristics of Pb2+ centres in undoped and Ce3+-doped Lu3Al5O12 single-crystalline films and Pb2+→Ce3+ energy transfer processes

International Nuclear Information System (INIS)

Babin, V.; Gorbenko, V.; Makhov, A.; Mares, J.A.; Nikl, M.; Zazubovich, S.; Zorenko, Yu.

2007-01-01

At 4.2-350 K, the steady-state and time-resolved emission and excitation spectra and luminescence decay kinetics were studied under excitation in the 2.5-15 eV energy range for the undoped and Ce 3+ -doped Lu 3 Al 5 O 12 (LuAG) single-crystalline films grown by liquid phase epitaxy method from the PbO-based flux. The spectral bands arising from the single Pb 2+ -based centres were identified. The processes of energy transfer from the host lattice to Pb 2+ and Ce 3+ ions and from Pb 2+ to Ce 3+ ions were investigated. Competition between Pb 2+ and Ce 3+ ions in the processes of energy transfer from the LuAG crystal lattice was evidenced especially in the exciton absorption region. Due to overlap of the 3.61 eV emission band of Pb 2+ centres with the 3.6 eV absorption band of Ce 3+ centres, an effective nonradiative energy transfer from Pb 2+ ions to Ce 3+ ions takes place, resulting in the appearance of slower component in the luminescence decay kinetics of Ce 3+ centres and decrease of the Ce 3+ -related luminescence intensity

Field enhanced luminescence of irradiated organics due to electron tunnelling

International Nuclear Information System (INIS)

Charlesby, A.

1981-01-01

Many organic materials, following exposure to high energy radiation at low temperatures, continue to emit light for long periods. One possible mechanism is that electrons trapped near their parent cations can tunnel back over long times depending on trap depth and distance. This luminescence can be greatly enhanced by the post-radiation application of an external electric field. Calculations on the kinetics of recombination by tunnelling for various trap depths and distances are extended to allow for the effect of an electrical field subsequently applied. The quantitative results lead to two methods of assessing trap depth, depending on immediate light enhancement and on its subsequent decay. The effect of field reversal is also explained. (author)

Luminescent properties in films of ZrO2: Dy

International Nuclear Information System (INIS)

Martinez, R. C.; Guzman, J.; Rivera, T.; Ceron, P.; Montes, E.; Guzman, D.; Garcia H, M.; Falcony, C.; Azorin, J.

2014-08-01

In this work the luminescent characterization of zirconium oxide (ZrO 2 ) films impure with dysprosium (Dy +3 ) is reported, obtained by means of the ultrasonics spray pyrolysis technique. The films were deposited on glass substrates (Corning), in a temperatures interval of 400 to 550 grades C, using as precursor elements Zirconium oxide chloride octahydrate (ZrOCl 2 ·8H 2 O) and Dysprosium tri-chloride (DyCl 3 ), dissolved in deionized water, varying the concentration of the contaminated from the 1 to 20 atomic % with relationship to the zirconium in solution. The luminescent characterization was analyzed by means of photoluminescence and thermoluminescence. The photoluminescence results showed a spectrum with three maxima which correspond to the electronic transitions 4 F 9/2 - 6 H 15/2 , 4 F 9/2 - 6 H 13/2 and 4 F 9/2 - 6 H 11/2 characteristics of the Dy 3+ ion. The thermoluminescence (Tl) response when being exposed to a monochrome UV beam in 240 nm showed a wide curve that exhibits a maxim centered in 200 grades C. The Tl response of ZrO 2 :Dy in function of the dose was shown lineal in the interval of 24 mJ/cm 2 to 432 mJ/cm 2 . A study of the repeatability and dissipation of the ZrO 2 :Dy Tl response is included. Considering the shown previous results we can conclude that the ZrO 2 in film form obtained by spray pyrolysis has luminescent properties in 240 nm. (Author)

Bi3+–Pr3+ energy transfer processes and luminescent properties of LuAG:Bi,Pr and YAG:Bi,Pr single crystalline films

International Nuclear Information System (INIS)

Zorenko, Y.; Gorbenko, V.; Savchyn, V.; Zorenko, T.; Nikl, M.; Mares, J.A.; Beitlerova, A.; Jary, V.

2013-01-01

Absorption, cathodoluminescence, excitation spectra of photoluminescence (PL) and PL decay kinetics were studied at 300 K for the double doped with Bi 3+ –Pr 3+ and separately doped with Bi 3+ and Pr 3+ Lu 3 Al 5 O 12 (LuAG) and Y 3 Al 5 O 12 (YAG) single crystalline film (SCF) phosphors grown by the liquid phase epitaxy method. The emission bands in the UV range arising from the intrinsic radiative transitions of Bi 3+ based centers, and emission bands in the visible range, related to the luminescence of excitons localized around Bi 3+ based centers, were identified both in Bi–Pr and Bi-doped LuAG and YAG SCFs. The energy transfer processes from the host lattice simultaneously to Bi 3+ and Pr 3+ ions and from Bi 3+ to Pr 3+ ions were investigated. Competition between Pr 3+ and Bi 3+ ions in the energy transfer processes from the LuAG and YAG hosts was evidenced. The strong decrease of the intensity of Pr 3+ luminescence both in LuAG:Pr and YAG:Pr SCFs phosphors, grown from Bi 2 O 3 flux, is observed due to the quenching influence of Bi 3+ flux related impurity. Due to overlap of the UV emission band of Bi 3+ centers with the f–d absorption bands of Pr 3+ ions in the UV range and the luminescence of excitons localized around Bi ions with the f–f absorption bands of Pr 3+ ions in the visible range, an effective energy transfer from Bi 3+ ions to Pr 3+ ions takes place in LuAG:Bi,Pr and YAG:Bi,Pr SCFs, resulting in the appearance of slower component in the decay kinetics of the Pr 3+ d–f luminescence. -- Highlights: • Bi and Pr doped film phosphor grown by liquid phase epitaxy method. • Energy transfer from Bi 3+ to Pr 3+ ions. • Strong quenching of the Pr 3+ luminescence by Bi 3+ co-dopant

Hydrothermal synthesis, characterization, and luminescence of Ca_2B_2O_5:RE (RE = Eu"3"+, Tb"3"+, Dy"3"+) nanofibers

International Nuclear Information System (INIS)

Yang, Li; Wan, Yingpeng; Li, Yuze; Pu, Yinfu; Huang, Yanlin; Chen, Cuili; Seo, Hyo Jin

2016-01-01

Ca_2B_2O_5:RE (RE = Eu"3"+, Tb"3"+, Dy"3"+) nanofibers were synthesized by the hydrothermal reaction method. The structural refinement was conducted on the base of the X-ray powder diffraction (XRD) measurements. The surface properties of the Ca_2B_2O_5:RE (RE = Eu"3"+, Tb"3"+, Dy"3"+) nanofibers were investigated by the measurements such as the scanning electron microscope (SEM), transmission electron microscope (TEM), and the energy dispersive spectrum (EDS). The nanofiber has a diameter of about 100 nm and a length of several micrometers. The luminescence properties such as photoluminescence excitation (PLE) and emission spectra (PL), decay lifetime, color coordinates, and the absolute internal quantum efficiency (QE) were reported. Ca_2B_2O_5:Eu"3"+ nanofibers show the red luminescence with CIE coordinates of (x = 0.41, y = 0.51) and the luminescence lifetime of 0.63 ms. The luminescence of Ca_2B_2O_5:Tb"3"+ nanofibers is green color (x = 0.29, y = 0.53) with the lifetime of 2.13 ms. However, Dy"3"+-doped Ca_2B_2O_5 nanofibers present a single-phase white-color phosphor with the fluorescence decay of 3.05 ms. Upon near-UV excitation, the absolute quantum efficiency is measured to be 65, 35, and 37 % for Eu"3"+-, Tb"3"+-, Dy"3"+-doped Ca_2B_2O_5 nanofibers, respectively. It is suggested that Ca_2B_2O_5:RE (RE = Eu"3"+, Tb"3"+, Dy"3"+) nanofibers could be an efficient phosphor for lighting and display.

Structural and luminescence properties of Mn{sup 2+} ions doped calcium zinc borophosphate glasses

Energy Technology Data Exchange (ETDEWEB)

Wan, Ming Hua, E-mail: wanminghua819@gmail.com [Phosphor Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Wong, Poh Sum, E-mail: pohsumwong@gmail.com [Phosphor Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Hussin, Rosli, E-mail: roslihussin@utm.my [Phosphor Research Group, Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Lintang, Hendrik O., E-mail: hendrik@ibnusina.utm.my [Catalytic Science and Technology (CST) Research Group, Ibnu Sina Institute for Fundamental Science Studies, Universiti Teknologi Malaysia, Skudai 81310, Johor (Malaysia); Endud, Salasiah, E-mail: salasiah@kimia.fs.utm.my [Department of Chemistry, Faculty of Science, Universiti Teknologi Malaysia, 81310 UTM Johor Bahru, Johor (Malaysia)

2014-05-15

Highlights: • FT-IR revealed that the network structures are from borate and phosphate network. • The PL spectrum exhibits a green emission band at 582 nm ({sup 4}T{sub 1g} → {sup 6}A{sub 1g}). • As the concentration of Mn{sup 2+} ions is increased, the emission band had been red shifted. • These glasses are found to have potential applications as luminescent optical materials. - Abstract: Calcium zinc borophosphate glasses (CaZnBP) doped with various concentrations of Mn{sup 2+} ions and borate and phosphate as variable were prepared using conventional melt quenching technique. The structure of obtained glasses were examined by means of use: X-ray diffraction (XRD) and fourier transform infrared (FT-IR). XRD analysis confirmed amorphous nature of glass samples. The FT-IR spectra reveals the presence of both borate and phosphate vibrational modes in the prepared glasses. The doping of Mn{sup 2+} ions (2–10 mol%) shows no significant changes in the main IR vibrational bands. Optical properties were studied by measuring the near infrared photoluminescence (PL) spectra. CaZnBP glasses exhibited intense green emission peak (582 nm) (tetrahedral symmetry), which is assigned to a transition from the upper {sup 4}T{sub 1g} → {sup 6}A{sub 1g} ground state of Mn{sup 2+} ions. As the concentration of Mn{sup 2+} ions increases, the emission band increases from 582 nm to 650 nm and exhibited a red light emission (octahedral symmetry). The decay curves of {sup 4}T{sub 1g} level were examined for all concentrations and the measured lifetimes are found to depend strongly on Mn{sup 2+} concentrations. From the emission characteristic parameters of {sup 6}A{sub 1g} (S) level, it shows that the CaZnBP glasses could have potential applications as luminescent optical materials, visible lasers and fluorescent display devices.

Application of the thermoluminescent (TL) and optically stimulated luminescence (OSL) dosimetry techniques to determinate the isodose curves in a cancer treatment planning simulation using Volumetric Modulated Arc Therapy - VMAT

International Nuclear Information System (INIS)

Bravim, Amanda

2015-01-01

The Volumetric Modulated Arc Therapy (VMAT) is an advance technique of Intensity Modulated Radiation Therapy (IMRT). This progress is due to the continuous gantry rotation with the radiation beam modulation providing lower time of the patient treatment. This research aimed the verification of the isodose curves in a simulation of a vertebra treatment with spinal cord protection using the thermoluminescent (TL) and optically stimulated luminescence (OSL) dosimetry techniques and the LiF:Mg,Ti (TLD-100), CaS0 4 :Dy and Al 2 0 3 :C dosimeters and LiF:Mg,Ti micro dosimeters (TLD-100). The dosimeters were characterized using PMMA plates of 30 x 30 x 30 cm 3 and different thickness. All irradiations were done using Truebeam STx linear accelerator of Hospital Israelita Albert Einstein, with 6 MV photons beam. After the dosimeter characterization, they were irradiated according the specific planning simulation and using a PMMA phantom developed to VMAT measurements. This irradiation aimed to verify the isodose curves of the treatment simulation using the two dosimetry techniques. All types of dosimeters showed satisfactory results to determine the dose distribution but analysing the complexity of the isodose curves and the proximity of them, the LiF:Mg,Ti micro dosimeter showed the most appropriate for use due to its small dimensions. Regarding the best technique, as both technique showed satisfactory results, the TL technique presents less complex to be used because the most of the radiotherapy departments already have a TL laboratory. The OSL technique requires more care and greater investment in the hospital. (author)

UV light induced red emission in Eu3+-doped zincborophosphate glasses

Science.gov (United States)

Hima Bindu, S.; Siva Raju, D.; Vinay Krishna, V.; Rajavardhana Rao, T.; Veerabrahmam, K.; Linga Raju, Ch.

2016-12-01

This paper reports the preparation of transparent zincborophosphate (ZBP) glasses doped with Eu3+ ions by the conventional melt quenching technique. The prepared glasses were characterized using powder XRD, FTIR, optical absorption, photoluminescence and decay curves. Judd-Ofelt (JO) intensity parameters calculated under various constraints using absorption and emission spectra. These JO intensity parameters have been used to predict the radiative properties such as radiative life time, branching ratios and stimulated emission cross section of the 5D0→7FJ (J = 0-4) transitions. Decay curves for the 5D0 level of Eu3+ ions shows single exponential for all concentrations. Luminescence properties of 5D0→7F2 transitions of Eu3+ions have revealed that the present ZBP:Eu3+ glasses have significant in optical applications at around 613 nm. An intense red luminescence has been observed due to 5D0→7F2 transition of Eu3+ ion in these glasses. From the CIE color coordinate diagram, it is observed that the present glass system is prominent material for red emission.

Luminescence dosemeter of the Al{sub 2}O{sub 3}:Er,Yb

Energy Technology Data Exchange (ETDEWEB)

Goncalves, Katia A.; Ventieri, Alexandre; Bitencourt, Jose F.S. [Universidade de Sao Paulo (EP/USP), SP (Brazil). Escola Politecnica. Dept. de Engenharia Eletrica; Mittani, Juan C.R.; Tatumi, Sonia H. [Faculdade de Tecnologia de Sao Paulo (CEETEPS), SP (Brazil)

2011-07-01

The present work deals with the thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) properties of {alpha}-Al{sub 2}O{sub 3}: Er,Yb obtained by sol gel process. Nanocrystals formations composed by Er{sub 2}O{sub 3}, Yb{sub 2}O{sub 3} and Yb{sub 3}Al{sub 5}O{sub 12} were observed by TEM images, EDS, electron beam diffraction and RXD, located at the surface of the alumina grains. The sample codoped with 1mol% of Er and 2 mol% of Yb supplied the best results for TL and OSL responses. The growth of the intensity of dosimetric TL peak at 205 deg C was linear with gamma radiation doses and the same behavior was observed in OSL growth curve. The luminescence fading of the sample after a dose of 5 Gy was found initially for a period of 30 days and minimum detectable dose measured for TL was 60.78 mGy and for OSL was 13.09 mGy. (author)

Investigation into scanning tunnelling luminescence microscopy

International Nuclear Information System (INIS)

Manson-Smith, S.K.

2001-01-01

This work reports on the development of a scanning tunnelling luminescence (STL) microscope and its application to the study of Ill-nitride semiconductor materials used in the production of light emitting devices. STL microscopy is a technique which uses the high resolution topographic imaging capabilities of the scanning tunnelling microscope (STM) to generate high resolution luminescence images. The STM tunnelling current acts as a highly localised source of electrons (or holes) which generates luminescence in certain materials. Light generated at the STM tunnelling junction is collected concurrently with the height variation of the tunnelling probe as it is scanned across a sample surface, producing simultaneous topographic and luminescence images. Due to the very localised excitation source, high resolution luminescence images can be obtained. Spectroscopic resolution can be obtained by using filters. Additionally, the variation of luminescence intensity with tunnel current and with bias voltage can provide information on recombination processes and material properties. The design and construction of a scanning tunnelling luminescence microscope is described in detail. Operating under ambient conditions, the microscope has several novel features, including a new type of miniature inertial slider-based approach motor, large solid-angle light collection optical arrangement and a tip-height regulation system which requires the minimum of operator input. (author)

Optically stimulated luminescence from quartz measured using the linear modulation technique

International Nuclear Information System (INIS)

Bulur, E.; Boetter-Jensen, L.; Murray, A.S.

2000-01-01

The optically stimulated luminescence (OSL) from heated natural quartz has been investigated using the linear modulation technique (LMT), in which the excitation light intensity is increased linearly during stimulation. In contrast to conventional stimulation, which usually produces a monotonically decreasing signal, linearly increasing the stimulation power gives peaks in the signal as a function of time. In cases where the OSL signal contains more than one component, the linear increase in power of the stimulation light may result in a curve containing overlapping peaks, where the most easily stimulated component occurs at a shorter time. This allows the separation of the overlapping OSL components, which are assumed to originate from different traps. The LM-OSL curve from quartz shows an initial peak followed by a broad one. Deconvolution using curve fitting has shown that the composite OSL curve from quartz can be approximated well by using a linear combination of first-order peaks. In addition to the three known components, i.e. fast, medium and slow components from continuous-wave-OSL studies, an additional slow component is also identified for the first time. The dose responses and thermal stabilities of the various components are also studied

Polymeric Luminescent Compositions Doped with Beta-Diketonates Boron Difluoride as Material for Luminescent Solar Concentrator

Science.gov (United States)

Khrebtov, A. A.; Fedorenko, E. V.; Reutov, V. A.

2017-11-01

In this paper we investigated polymeric luminescent compositions based on polystyrene doped with beta diketonates boron difluoride. Transparent films with effective absorption in the ultraviolet and blue regions of the spectrum were obtained. Polymeric luminescent compositions based on the mixture of dyes allow expanding the absorption region and increase the radiation shift. A luminescent solar concentrator consisting of a glass plate coated with such film can be used for photovoltaic window application.

Sample and plume luminescence in fast heavy ion induced desorption

International Nuclear Information System (INIS)

Tuszynski, W.; Koch, K.; Hilf, E.R.

1996-01-01

The luminescence arising in 252 Cf-fission fragment induced desorption events has been measured using the time-correlated single photon counting technique. Photons emitted from the sample have been guided from a plasma desorption ion source to a photodetector by an optical fibre. Spectra and decay functions have been obtained using thin layers of Coronene or POPOP as samples. The results are strongly dependent on the acceleration field applied for ion extraction. Approximately 10 photons per fission fragment have been produced when applying no accelerating voltage. The results clearly show that these photons come from radiative electronic relaxations of molecules in the solid sample. Considerably more photons per fission fragment have been produced when applying a positive acceleration voltage. The intensity increases almost linearly for acceleration fields below 10 kV/cm and saturates at a nearly 10-fold higher value when compared to no acceleration. The intensity is also affected by the homogeneity of the accelerating field. These additional photons are attributed to radiative electronic relaxations of desorbed neutral molecules in the plume excited by inelastic collisions with accelerated positive ions. No additional photons have been observed when extracting negative ions. The negative ions produced do obviously not hit and/or excite desorbed neutral molecules, presumably due to their specific desorption characteristics. The experimental data have been analyzed by comparing with the cw and time-resolved sample luminescence obtained by optical excitation. The findings demonstrate that valuable information on ion-solid interactions, on specific desorption quantities and on processes in the plume can be obtained by measuring and analyzing the luminescence induced by the impact of high energy primary ions. (orig.)

LHCb Turbo++ Slimming: Inclusive B Hadron Decay Product Selection

CERN Document Server

Bogensberger, David

2016-01-01

My summer student project focused on reducing the turbo++ output bandwidth for B meson decays at LHCb. The aim is to discard as many of the background tracks as possible, while still retaining almost all of the signal events. I analysed the ability to distinguish signal from background tracks, by considering four different B meson decays, while using signal definitions for just one particular decay, as well as for a general type of decay. I added tracks to a triggered turbo candidate, to reconstruct the B meson. I used a boosted decision tree and an artificial neural network to classify events, and compared the resulting ROC curves.

What is the origin of concentration quenching of Cu{sup +} luminescence in glass?

Energy Technology Data Exchange (ETDEWEB)

Jiménez, José A., E-mail: jimenez.materials@gmail.com

2016-10-01

Monovalent copper-doped luminescent glasses are attractive materials for white light-emitting devices, photonic waveguides, and solar spectral conversion in photovoltaic cells. However, the occurrence of concentration quenching in such is not fully understood at present. In this work, calcium-phosphate glasses with high concentrations of luminescent Cu{sup +} ions have been prepared by a simple melt-quench method via CuO and SnO co-doping. The aim is to elucidate the origin of concentration quenching of Cu{sup +} light emission. A spectroscopic characterization was carried out by optical absorption and photoluminescence (PL) spectroscopy including emission decay dynamics. The concentrations of both CuO and SnO dopants were varied as 5, 10 and 15 mol%. Monovalent copper content is estimated in the CuO/SnO-containing glasses following the assessment of the concentration dependence of Cu{sup 2+} absorption in the visible for CuO singly-doped glasses. Contrary to the conventionally acknowledged direct Cu{sup +}→Cu{sup 2+} transfer, the data supports a Cu{sup +}–Cu{sup +} energy migration channel at the origin of the PL quenching.

Preparation and determination of the luminescent characteristics of ZrO{sub 2} in powder; Preparacion y determinacion de las caracteristicas luminiscentes del ZrO{sub 2} en polvo

Energy Technology Data Exchange (ETDEWEB)

Rivera M, T. [ESIME-IPN Unidad Culhuacan Mexico D.F. (Mexico); Olvera T, L.; Azorin N, J.; Soto E, A.M.; Velazquez O, C.; Campero C, A. [UAM-I, 09340 Mexico D.F. (Mexico)

2004-07-01

In this work the luminescent characteristics of the ZrO{sub 2} are presented using the method of Thermally Stimulated Luminescence (TSL), also called thermoluminescence (Tl). The powders of ZrO{sub 2} were obtained by two preparation methods: for precipitation and for evaporation of Sol-gel. The luminescent characteristics of the ZrO{sub 2} are determined using a lamp of radiation of UV light and a radiation source of beta particles of {sup 90}Sr/{sup 90}Y. Using the method of thermal stimulation the curve representative thermoluminescent of the previously irradiated material was obtained. The curve Tl of the ZrO{sub 2} irradiated with UV light presents a maximum in 180 C. Likewise, the spectrum of the curve Tl of the ZrO{sub 2} irradiated with particles beta presents a maximum centered in 181 C. While using gamma radiation like excitement source one has a spectrum with a peak centered in 184 C. When subjecting the materials obtained by sol-gel to a process of calcination at 1000 C for 24 hours a curved Tl it presents with two maxim in 185 and in 290 C respectively. The intensity of the response induced in the material it is a decisive factor to continue studying the dosimetric characteristics of the ZrO{sub 2} what allows to consider it as a potential material to use it in the beta particle dosimetry and of the UV light using the thermoluminescence method (Tl). (Author)

Luminescence sensitivity changes in quartz

CERN Document Server

Wintle, A G

1999-01-01

In the luminescence dating of sedimentary or heated quartz, some heat treatment is usually applied to the sample immediately prior to the measurement of the optically stimulated luminescence. In this paper we report experiments on a 30,000-year-old sedimentary quartz, in which we use the luminescence response to a test dose to monitor the changes in sensitivity that are caused by holding the quartz at temperatures from 160 to 280 deg. C for times from 10 s to 22 h. For an optically bleached sample, the monitoring is by both optically stimulated luminescence and the 110 deg. C TL peak; both luminescence signals are shown to have the same sensitisation (i.e. activation energy) characteristics. For natural or laboratory irradiated samples only the 110 deg. C TL peak can be used; sensitivity increases of up to a factor of 1.3 and 3 are observed for the natural and laboratory irradiated aliquots, respectively. Up to four exponential components are used to deconvolve the sensitivity change data; the dominant compon...

Luminescence in medical image science

Energy Technology Data Exchange (ETDEWEB)

Kandarakis, I.S., E-mail: kandarakis@teiath.gr

2016-01-15

Radiation detection in Medical Imaging is mostly based on the use of luminescent materials (scintillators and phosphors) coupled to optical sensors. Materials are employed in the form of granular screens, structured (needle-like) crystals and single crystal transparent blocks. Storage phosphors are also incorporated in some x-ray imaging plates. Description of detector performance is currently based on quality metrics, such as the Luminescence efficiency, the Modulation Transfer Function (MTF), the Noise Power Spectrum (NPS) and the Detective Quantum Efficiency (DQE) can be defined and evaluated. The aforementioned metrics are experimental evaluated for various materials in the form of screens. A software was designed (MINORE v1) to present image quality measurements in a graphical user interface (GUI) environment. Luminescence efficiency, signal and noise analysis are valuable tools for the evaluation of luminescent materials as candidates for medical imaging detectors. - Highlights: • Luminescence based medical imaging detectors. • Image science: MTF, NPS, DQE. • Phosphors screens light emission efficiency experimental evaluation. • Theoretical models for estimation of phosphor screen properties. • Software for medical image quality metrics.

Surface Temperature Measurements from a Stator Vane Doublet in a Turbine Engine Afterburner Flame Using a YAG:Tm Thermographic Phosphor

Science.gov (United States)

Eldridge, J. I.; Walker, D. G.; Gollub, S. L.; Jenkins, T. P.; Allison, S. W.

2015-01-01

Luminescence-based surface temperature measurements were obtained from a YAG:Tm-coated stator vane doublet exposed to the afterburner flame of a J85 test engine at University of Tennessee Space Institute (UTSI). The objective of the testing was to demonstrate that reliable surface temperatures based on luminescence decay of a thermographic phosphor producing short-wavelength emission could be obtained from the surface of an actual engine component in a high gas velocity, highly radiative afterburner flame environment. YAG:Tm was selected as the thermographic phosphor for its blue emission at 456 nm (1D23F4 transition) and UV emission at 365 nm (1D23H6 transition) because background thermal radiation is lower at these wavelengths, which are shorter than those of many previously used thermographic phosphors. Luminescence decay measurements were acquired using a probe designed to operate in the afterburner flame environment. The probe was mounted on the sidewall of a high-pressure turbine vane doublet from a Honeywell TECH7000 turbine engine coated with a standard electron-beam physical vapor deposited (EB-PVD) 200-m-thick TBC composed of yttria-stabilized zirconia (YSZ) onto which a 25-m-thick YAG:Tm thermographic phosphor layer was deposited by solution precursor plasma spray (SPPS). Spot temperature measurements were obtained by measuring luminescence decay times at different afterburner power settings and then converting decay time to temperature via calibration curves. Temperature measurements using the decays of the 456 and 365 nm emissions are compared. While successful afterburner environment measurements were obtained to about 1300C with the 456 nm emission, successful temperature measurements using the 365 nm emission were limited to about 1100C due to interference by autofluorescence of probe optics at short decay times.

Plasmon-enhanced optically stimulated luminescence

International Nuclear Information System (INIS)

Guidelli, E. J.; Baffa, O.; Ramos, A. P.

2015-10-01

Full text: Optically Stimulated Luminescence dosimeters (OSLD) have been largely used for personal, medical, and industrial radiation dosimetry. Developing highly sensitive and small-sized radiation detectors and dosimeters is essential for improving spatial resolution and consequently diagnosis quality and treatment efficacy in the case of applications in radiodiagnosis and radiation therapy, for instance. Conventional methods to improve the OSLD sensitivity consist of doping and co-doping the host materials with atoms of other elements, thereby increasing the amount of trapping and/or luminescent centers. Our group is researching on the use of the plasmon properties of noble metal nanoparticles to increase OSL intensity. Upon incidence of a light beam with appropriate resonant wavelengths, the oscillation of the free electrons at the nanoparticle surface originates the Localized Surface Plasmons (LSP) and the consequent plasmon resonance band. The interaction between the LSP and the surrounding luminescent material leads to new optical properties largely employed for enhancing several luminescent processes. Here we will show our results regarding the use of LSP to increase OSLD sensitivity. The interaction between the traps/luminescent centers and the plasmons depends on the distance between them, on the plasmon resonance band intensity and position, as well as on the surrounding medium. Therefore, the plasmon-enhanced luminescence is a promising tool to develop more sensitive and miniaturized OSLD. (Author)

Plasmon-enhanced optically stimulated luminescence

Energy Technology Data Exchange (ETDEWEB)

Guidelli, E. J.; Baffa, O. [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Fisica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil); Ramos, A. P., E-mail: ederguidelli@gmail.com [Universidade de Sao Paulo, Faculdade de Filosofia, Ciencias e Letras de Ribeirao Preto, Departamento de Quimica, Av. Bandeirantes 3900, 14040-901 Ribeirao Preto, Sao Paulo (Brazil)

2015-10-15

Full text: Optically Stimulated Luminescence dosimeters (OSLD) have been largely used for personal, medical, and industrial radiation dosimetry. Developing highly sensitive and small-sized radiation detectors and dosimeters is essential for improving spatial resolution and consequently diagnosis quality and treatment efficacy in the case of applications in radiodiagnosis and radiation therapy, for instance. Conventional methods to improve the OSLD sensitivity consist of doping and co-doping the host materials with atoms of other elements, thereby increasing the amount of trapping and/or luminescent centers. Our group is researching on the use of the plasmon properties of noble metal nanoparticles to increase OSL intensity. Upon incidence of a light beam with appropriate resonant wavelengths, the oscillation of the free electrons at the nanoparticle surface originates the Localized Surface Plasmons (LSP) and the consequent plasmon resonance band. The interaction between the LSP and the surrounding luminescent material leads to new optical properties largely employed for enhancing several luminescent processes. Here we will show our results regarding the use of LSP to increase OSLD sensitivity. The interaction between the traps/luminescent centers and the plasmons depends on the distance between them, on the plasmon resonance band intensity and position, as well as on the surrounding medium. Therefore, the plasmon-enhanced luminescence is a promising tool to develop more sensitive and miniaturized OSLD. (Author)

Thermally stimulated luminescence and persistent luminescence of β-irradiated YAG:Pr"3"+ nanophosphors produced by combustion synthesis

International Nuclear Information System (INIS)

Santacruz-Gomez, K.; Meléndrez, R.; Gil-Tolano, M.I.; Jimenez, J.A.; Makale, M.T.; Barboza-Flores, M.; Castaneda, B.; Soto-Puebla, D.; Pedroza-Montero, M.; McKittrick, J.; Hirata, G.A.

2016-01-01

In this work, the thermally stimulated luminescence (TSL) and persistent luminescence (PLUM) properties of praseodymium doped yttrium aluminum garnet (YAG:Pr"3"+) exposed to β-irradiation are reported. X-ray diffraction (XRD) confirms a single phase of YAG obtained by the combustion method. Transmission electron microscopy (TEM) shows that powder particles appear to be irregular crystals with an average size of 67 nm. TSL glow-curve deconvolution of YAG:Pr"3"+ after β-irradiation consist in six peaks centered at 394, 450, 467, 543, 637 and 705 K. The TSL fading and PLUM signals were found to be associated with at least with two different kinds of traps, corresponding to the peaks located at 394, 450 and 467 K. YAG:Pr"3"+ nanophosphors analyzed in this work showed interesting features about the dosimetric sensitivity as well as the reproducibility for both TSL/PLUM techniques, with good linearity dose response. These results indicate that nanocrystalline YAG:Pr3"+ is a good candidate for dosimetric applications in the range of 80 mGy-20 Gy. - Highlights: • β-irradiated YAG:Pr"3"+ TSL consist in 394, 450, 467, 543, 637 and 705 K peaks. • YAG:Pr"3"+ is a good candidate for dosimetry in the range of 80 mGy-20 Gy. • PLUM can be potentially used for in vivo, in situ and quasi in real time dosimetry.

Thermoluminescence glow curves of irradiated PMMA and low density polyethylene

International Nuclear Information System (INIS)

Matsuda, Koji; Nakase, Yoshiaki; Kumakiri, Yasuhito; Tsuji, Yoshio.

1985-03-01

Light emission from polymers is observed when polymers preirradiated with ionizing radiation at low temperature are heated gradually. The light emission is supposedly resulted from recombination of electrons with active centers produced in polymers or from some other processes involving charge transfer, but no definite explanation has been given at present on the thermoluminescent centers. This report describes our studies on the effects of impurities contained in polymers and pressure of ambient gases on the thermoluminescent glow curve of PMMA and low density polyethylene, which are often used for plastic film dosimeters. In the glow curve of PMMA, only one peak was observed at 110 K in an H 2 or He atmosphere at 760 Torr, but the intensity of the peak decreased with decreasing the H 2 or He gas pressure. At 10 -5 Torr H 2 or He atmosphere the peak disappered, and two sharp peaks appeared in the temperature range from 200 to 250 K. On the other hand, in the glow curve of low density polyethylene, three peaks were observed at 120 K, 180 K and 250 K in the presence of H 2 or He gas at 760 Torr. The effects of pressure of ambient gases and impurities in the polyethylene on these peaks indicate that the peak at 120 K is due to luminescent center produced on the surface or just below the surface of the matrix by collision of excited atoms or molecules of gases with polymer molecules, the peak at 120 K is originated from impurities in the matrix, and the peak at 250 0 K corresponds to luminescent center produced in polyethylene matrix. (author)

Luminescence of LiH(D):Ru monocrystals

International Nuclear Information System (INIS)

Sabirzyanov, A.A.; Oparin, D.V.; Pilipenko, G.I.; Gavrilov, F.F.

1993-01-01

Luminescence of lithium hydride (deuteride) activated by ruthenium is recorded for the first time. The features connected with the structure and oscillations of the basic lattice are detected in luminescence spectrum. The qualitative model of luminescence spectrum is suggested

Life-time resolved emission spectra in CdI2 crystals

International Nuclear Information System (INIS)

Kawabata, Seiji; Nakagawa, Hideyuki

2007-01-01

The emission spectrum of CdI 2 is composed of ultraviolet (UV), green (G) and yellow (Y and Y') bands peaking at 3.38, 2.50, 2.16 and 2.25 eV, respectively. In order to determine the initial states of the Y- and G-luminescence, decay curves have been measured at 6 and 80 K by varying emission energy. The observed decay curves are composed of two or three exponential components. These decay components were named τ 1 , τ 2 , τ 3 , τ 3' and τ 4 . The emission spectrum for each decay component, i.e., the life-time resolved emission spectrum, was constructed from the observed decay curves. At 6 K, three bands at 2.12, 2.49 and 2.64 eV are obtained for τ 1 , τ 2 and τ 3 components, respectively. At 80 K, a dominant band for the τ 4 component and a weak band for the τ 3' component appear on the same energy position at 2.25 eV. The origin of each emission band in the life-time resolved emission spectra will be briefly discussed

Optically stimulated luminescence (OSL) of dental enamel for retrospective assessment of radiation exposure

International Nuclear Information System (INIS)

Yukihara, E.G.; Mittani, J.; McKeever, S.W.S.; Simon, S.L.

2007-01-01

This paper briefly reviews the optically stimulated luminescence (OSL) properties of dental enamel and discusses the potential and challenges of OSL for filling the technology gap in biodosimetry required for medical triage following a radiological/nuclear accident or terrorist event. The OSL technique uses light to stimulate a radiation-induced luminescence signal from materials previously exposed to ionizing radiation. This luminescence originates from radiation-induced defects in insulating crystals and is proportional to the absorbed dose of ionizing radiation. In our research conducted to date, we focused on fundamental investigations of the OSL properties of dental enamel using extracted teeth and tabletop OSL readers. The objective was to obtain information to support the development of the necessary instrumentation for retrospective dosimetry using dental enamel in laboratory, or for in situ and non-invasive accident dosimetry using dental enamel in emergency triage. An OSL signal from human dental enamel was detected using blue, green, or IR stimulation. Blue/green stimulation associated with UV emission detection seems to be the most appropriate combination in the sense that there is no signal from un-irradiated samples and the shape of the OSL decay is clear. Improvements in the minimum detection level were achieved by incorporating an ellipsoidal mirror in the OSL system to maximize light collection. Other possibilities to improve the sensitivity and research steps necessary to establish the feasibility of the technique for retrospective assessment of radiation exposure are also discussed

Luminescence and scintillation properties of Ce-doped Cs2ZnCl4 crystals

Science.gov (United States)

Sugawara, K.; Koshimizu, M.; Yanagida, T.; Fujimoto, Y.; Haruki, R.; Nishikido, F.; Kishimoto, S.; Asai, K.

2015-03-01

In this study, we have synthesized scintillation materials based on Ce-doped Cs2ZnCl4 crystals. The light yield was enhanced by up to 20% by doping Cs2ZnCl4 with Ce3+ ions. In the scintillation time profiles, fast components exhibited decay time constants on the order of nanoseconds, which was ascribed to Auger-free luminescence (AFL). The light yield of the AFL component decreased at 10 mol% Ce3+ concentration, which is mainly attributed to the reabsorption of AFL photons inside the crystals by Ce3+ ions, as seen in the scintillation spectra. Long components had decay time constants of approximately 30 ns. In addition, at 10 mol% Ce3+ concentration, a prominent band appeared at approximately 500 nm in the scintillation spectrum, which was not observed in the photoluminescence spectra. The long components in the scintillation time profiles and the 500 nm band in the scintillation spectra were tentatively attributed to self-trapped excitons perturbed by Ce3+ ions.

Material for a luminescent solar concentrator

Science.gov (United States)

Andrews, L.J.

1984-01-01

A material for use in a luminescent solar concentrator, formed by ceramitizing the luminescent ion Cr/sup 3 +/ with a transparent ceramic glass containing mullite. The resultant material has tiny Cr/sup 3 +/-bearing crystallites dispersed uniformly through an amorphous glass. The invention combines the high luminescent efficiency of Cr/sup 3 +/ in the crystalline phase with the practical and economical advantages of glass technology.

Persistent luminescence, TL and OSL characterization of beta irradiated SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+} combustion synthesized phosphor

Energy Technology Data Exchange (ETDEWEB)

Zúñiga-Rivera, N.J. [Departamento de Física, Posgrado en Nanotecnología, Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico); García, R.; Rodríguez-Mijangos, R.; Chernov, V.; Meléndrez, R.; Pedroza-Montero, M. [Departamento de Investigación en Física, Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico); Barboza-Flores, M., E-mail: mbarboza@cifus.uson.mx [Departamento de Investigación en Física, Universidad de Sonora, Hermosillo, Sonora 83000 (Mexico)

2014-05-01

The persistent luminescence (PLUM), thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of strontium aluminates co-doped with Eu{sup +2} and Dy{sup +3} exposed to beta radiation is reported. The phosphor was synthesized by the combustion synthesis method employing a highly exothermic redox reaction between the metal nitrates [Al(NO{sub 3}){sub 3}, Sr(NO{sub 3}){sub 2}, Eu(NO{sub 3}){sub 3} and Dy(NO{sub 3}){sub 3}] and organic fuel carbohydrazide (CH{sub 6}N{sub 4}O). The long decay PLUM emission, TL and OSL were measured as a function of beta radiation dose. A wide emission band centered at 510 nm (green) related to Eu{sup 2+} ions and lattice defects were observed for the synthesized samples. The presence of a variety of defects and aggregates were responsible for the observed broad 100 °C peaked TL glow curve of the irradiated sample which is composed of several overlapped TL peaks. The existence of multiple trapping levels, with different trapping/detrapping probabilities, is behind the particular features for the PLUM, TL and OSL emissions. We conclude that in the SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+} phosphors, the low temperature TL peaked around 30–75 °C is responsible for the PLUM emission and those around 100 °C were related to very stable trapping states which provide suitable radiation storage properties to be used as a PLUM/TL/OSL radiation phosphor.

Virulence of luminescent and non-luminescent isogenic vibrios towards gnotobiotic Artemia franciscana larvae and specific pathogen-free Litopenaeus vannamei shrimp.

Science.gov (United States)

Phuoc, L H; Defoirdt, T; Sorgeloos, P; Bossier, P

2009-04-01

This study was conducted to test the virulence of luminescent (L) and non-luminescent (NL) isogenic strains of Vibrio campbellii LMG21363, Vibrio harveyi BB120 (wild type) and quorum-sensing mutant strains derived from the wild type such as Vibrio harveyi BB152, BB170, MM30 and BB886. The NL strains could be obtained by culturing rifampicin-resistant luminescent strains in the dark under static condition. The virulence of the L and NL strains was tested in gnotobiotic Artemia franciscana larvae challenged with 10(4) CFU ml(-1) of bacteria. All luminescent isogenic tested strains showed higher virulence compared to the NL strains. The virulence of L and NL V. campbellii and V. harveyi BB120 was also tested in specific pathogen-free juvenile shrimp upon intramuscular injection with 10(6) CFU of bacteria. In contrast with Artemia, there was no significant difference in mortality between the groups challenged with L and NL strains (P > 0.05). The non-luminescent strains were not able to revert back to the luminescent state and quorum sensing did not influence this phenotypic shift. Luminescent Vibrio strains can switch to a non-luminescent state by culturing them in static conditions. The NL strains become less virulent as verified in Artemia. The luminescent state of Vibrio cells in a culture needs to be verified in order to assure maintenance of virulence.

X-ray-excited optical luminescence of protein crystals: a new tool for studying radiation damage during diffraction data collection.

Science.gov (United States)

Owen, Robin L; Yorke, Briony A; Pearson, Arwen R

2012-05-01

During X-ray irradiation protein crystals radiate energy in the form of small amounts of visible light. This is known as X-ray-excited optical luminescence (XEOL). The XEOL of several proteins and their constituent amino acids has been characterized using the microspectrophotometers at the Swiss Light Source and Diamond Light Source. XEOL arises primarily from aromatic amino acids, but the effects of local environment and quenching within a crystal mean that the XEOL spectrum of a crystal is not the simple sum of the spectra of its constituent parts. Upon repeated exposure to X-rays XEOL spectra decay non-uniformly, suggesting that XEOL is sensitive to site-specific radiation damage. However, rates of XEOL decay were found not to correlate to decays in diffracting power, making XEOL of limited use as a metric for radiation damage to protein crystals. © 2012 International Union of Crystallography

A computer method for simulating the decay of radon daughters

International Nuclear Information System (INIS)

Hartley, B.M.

1988-01-01

The analytical equations representing the decay of a series of radioactive atoms through a number of daughter products are well known. These equations are for an idealized case in which the expectation value of the number of atoms which decay in a certain time can be represented by a smooth curve. The real curve of the total number of disintegrations from a radioactive species consists of a series of Heaviside step functions, with the steps occurring at the time of the disintegration. The disintegration of radioactive atoms is said to be random but this random behaviour is such that a single species forms an ensemble of which the times of disintegration give a geometric distribution. Numbers which have a geometric distribution can be generated by computer and can be used to simulate the decay of one or more radioactive species. A computer method is described for simulating such decay of radioactive atoms and this method is applied specifically to the decay of the short half life daughters of radon 222 and the emission of alpha particles from polonium 218 and polonium 214. Repeating the simulation of the decay a number of times provides a method for investigating the statistical uncertainty inherent in methods for measurement of exposure to radon daughters. This statistical uncertainty is difficult to investigate analytically since the time of decay of an atom of polonium 218 is not independent of the time of decay of subsequent polonium 214. The method is currently being used to investigate the statistical uncertainties of a number of commonly used methods for the counting of alpha particles from radon daughters and the calculations of exposure

Study of N-13 decay on time using continuous kinetic function method

International Nuclear Information System (INIS)

Tran Dai Nghiep; Vu Hoang Lam; Nguyen Ngoc Son; Nguyen Duc Thanh

1993-01-01

The decay function from radioisotope 13 N formed in the reaction 14 N(γ,n) 13 N was registered by high resolution gamma spectrometer in multiscanning mode with gamma energy 511 keV. The experimental data was processed by common and kinetic function method. The continuous comparison of the decay function on time permits to determinate possible deviation from purely exponential decay curve. The results were described by several decay theories. The degrees of corresponding between theories and experiment were evaluated by goodness factor. A complex type of decay was considered. (author). 9 refs, 2 tabs, 6 figs

Luminescence of uranyl ion complexed with 2,6-pyridine dicarboxylic acid as ligand in acetonitrile medium. Observation of co-luminescence

Energy Technology Data Exchange (ETDEWEB)

Maji, Siuli; Kumar, Satendra; Sankaran, Kannan [Indira Ghandi Centre for Atomic Research, Tamil Nadu (India). Materials Chemistry Div.

2017-10-01

Luminescence from UO{sub 2}{sup 2+} (uranyl ion) complexed with 2,6-pyridine dicarboxylic acid (PDA) has been studied using acetonitrile (MeCN) as solvent between pH 1.0 and 6.0. The enhancement in luminescence intensity because of sensitization by PDA in the non-aqueous environment provided by the MeCN is found to be one order better than in aqueous medium. The luminescence is further enhanced by about four times following the addition of Y{sup 3+}; a process known as co-luminescence. This is the first study on co-luminescence of uranyl ion in its PDA complex. Lifetime studies indicate the presence of two species having different micro-environments. Formations of both intra and inter molecular complexes are believed to be responsible for enhancement due to co-luminescence.

Luminescence of uranyl ion complexed with 2,6-pyridine dicarboxylic acid as ligand in acetonitrile medium. Observation of co-luminescence

International Nuclear Information System (INIS)

Maji, Siuli; Kumar, Satendra; Sankaran, Kannan

2017-01-01

Luminescence from UO_2"2"+ (uranyl ion) complexed with 2,6-pyridine dicarboxylic acid (PDA) has been studied using acetonitrile (MeCN) as solvent between pH 1.0 and 6.0. The enhancement in luminescence intensity because of sensitization by PDA in the non-aqueous environment provided by the MeCN is found to be one order better than in aqueous medium. The luminescence is further enhanced by about four times following the addition of Y"3"+; a process known as co-luminescence. This is the first study on co-luminescence of uranyl ion in its PDA complex. Lifetime studies indicate the presence of two species having different micro-environments. Formations of both intra and inter molecular complexes are believed to be responsible for enhancement due to co-luminescence.

Receptor-Targeted Luminescent Silver Bionanoparticles

NARCIS (Netherlands)

Bunschoten, Anton; Chin, Patrick T.K.; Buckle, Tessa; Linden, van der Marte; Barendregt, Arjan; Verheijen, Marcel A.; Leeuwen, van Fijs W.B.

2016-01-01

Luminescent Ag nanoclusters (Ag-NC) provide the next generation in bionanoparticles, wherein the luminescence (650 nm) and large Stokes shift of these inorganic nanoclusters are favorable for biological imaging. By combining these characteristics with those of human serum albumin (HSA; a protein

Reflection measurements for luminescent powders

Science.gov (United States)

Kroon, R. E.

2018-04-01

Luminescent materials are useful in applications varying from lighting and display technologies to document security features and medical research, amongst many others. Measurement of the excitation range is an important consideration, and absorption bands are often determined from a decrease in the measured diffuse reflectance of the material using a ultraviolet-visible (UV-vis) spectrophotometer with an integrating sphere. Such a system may provide questionable results when used to measure the reflectance of a luminescence material, which is demonstrated for a Tb doped silica phosphor, because the system cannot differentiate between the reflected light and luminescence. It is shown that more reliable results are achieved for this phosphor by measuring the reflectance using a synchronous zero-offset scan in a fluorescence spectrometer equipped with an integrating sphere. This method is therefore recommended instead of traditional reflectance measurements using a UV-vis spectrophotometer for luminescent powders.

Near-Infrared Quantum Cutting Long Persistent Luminescence

OpenAIRE

Zou, Zehua; Feng, Lin; Cao, Cheng; Zhang, Jiachi; Wang, Yuhua

2016-01-01

By combining the unique features of the quantum cutting luminescence and long persistent luminescence, we design a new concept called ?near-infrared quantum cutting long persistent luminescence (NQPL)?, which makes it possible for us to obtain highly efficient (>100%) near-infrared long persistent luminescence in theory. Guided by the NQPL concept, we fabricate the first NQPL phosphor Ca2Ga2GeO7:Pr3+,Yb3+. It reveals that both the two-step energy transfer of model (I) and the one-step energy ...

Enhancing and quenching luminescence with gold nanoparticle films: the influence of substrate on the luminescent properties

International Nuclear Information System (INIS)

Guidelli, Eder José; Baffa, Oswaldo; Ramos, Ana Paula

2016-01-01

Gold nanoparticle (AuNP) films were sputtered over glass and aluminum substrates to enhance optically stimulated luminescence (OSL), a luminescent technique employed for radiation detection, from x-ray irradiated NaCl nanocrystals. The AuNP films deposited over glass led to enhanced-OSL emission, whereas the AuNP films deposited on aluminum substrates quenched the OSL emission. The enhanced-OSL intensity is proportional to the optical density of the film's plasmon resonance band at the stimulation wavelength. For the case of the AuNP/aluminum films, the luminescence quenching diminishes, and OSL intensity partially recovers upon increasing the distance between the AuNPs and the aluminum substrates, and between the luminescent nanocrystals and the AuNP films. These results suggest that plasmonic interactions between the emitter nanocrystals, the localized surface plasmons (LSP) of the AuNPs, and the substrate are responsible for the OSL enhancement and quenching. In this sense, the substrate dictates whether LSP relaxation occurs by radiative or non-radiative transisitions, leading to enhanced or quenched OSL, respectively. Therefore, besides showing that AuNP films can enhance and/or tune the sensitivity of luminescent radiation detectors, and demonstrating OSL as a new technique to investigate mechanisms of plasmon-enhanced luminescence, these results bring insights on how substrates strongly modify the optical properties of AuNP films. (paper)

Luminescence and excited state dynamics of Bi{sup 3+} centers in Y{sub 2}O{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Babin, V. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Chernenko, K., E-mail: nuclearphys@yandex.ru [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Peter the Great Saint-Petersburg Polytechnic University, Polytekhnicheskaya 29, 195251 St. Petersburg (Russian Federation); Lipińska, L. [Institute of Electronic Materials Technology, Wólczyńska 133, 01919 Warsaw (Poland); Mihokova, E.; Nikl, M. [Institute of Physics AS CR, Cukrovarnicka 10, 16200 Prague (Czech Republic); Schulman, L.S. [Physics Department, Clarkson University, Potsdam, NY 13699-5820 (United States); Shalapska, T. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Suchocki, A. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Institute of Physics, University of Bydgoszcz, Weyssenhoffa 11, 85072 Bydgoszcz (Poland); Zazubovich, S. [Institute of Physics, University of Tartu, Ravila 14c, 50411 Tartu (Estonia); Zhydachevskii, Ya. [Institute of Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw (Poland); Lviv Polytechnic National University, Bandera 12, 79646 Lviv (Ukraine)

2015-11-15

Photoluminescence of Y{sub 2}O{sub 3}:Bi nanopowder synthesized by the modified sol–gel method is studied using time-resolved luminescence spectroscopy in the 4.2–300 K temperature range. Bi{sup 3+} ions are substituted for Y{sup 3+} ions in two different crystal lattice sites, one having S{sub 6} symmetry (Bi(S{sub 6})) and the other C{sub 2} symmetry (Bi(C{sub 2})). The luminescence characteristics of these two centers are found to have strongly different electron–phonon interactions. The luminescence of Bi(S{sub 6}) and Bi(C{sub 2}) centers peak at 3.04 eV and 2.41 eV, respectively, and arise from the radiative decay of the triplet relaxed excited state (RES) of Bi{sup 3+} ions. The model and structure of the RES, responsible for the luminescence of Bi(S{sub 6}) and Bi(C{sub 2}) centers in Y{sub 2}O{sub 3}:Bi, as well as radiative and nonradiative processes, taking place in the excited states of these centers, are investigated. The parameters of the triplet RES (the separation between the metastable and radiative levels and probabilities of radiative and nonradiative transitions from these levels) are determined. Low-temperature quenching of the triplet luminescence of these centers is explained by nonradiative quantum tunneling transitions from the metastable minima of their triplet RES to closely located defect- or exciton-related levels. - Highlights: • Photoluminescence of Bi{sup 3+} centers of two types in Y{sub 2}O{sub 3}:Bi is investigated. • Bi(S{sub 6}) and Bi(C{sub 2}) centers reveal strongly different electron–phonon interaction. • Radiative and nonradiative processes in their triplet excited states are clarified. • Low-temperature luminescence quenching in Bi(S{sub 6}) and Bi(C{sub 2}) centers is studied. • New fast weak ≈2.9 eV emission is suggested to arise from Bi(C{sub 2}) centers.

Preparation and luminescence properties of Ce3+ and Ce3+/Tb(3+)-activated Y4Si2O7N2 phosphors.

Science.gov (United States)

Xia, Zhiguo; Wu, Weiwei

2013-09-28

Ce(3+) and Ce(3+)/Tb(3+)-activated Y4Si2O7N2 phosphors are synthesized by the solid-state method, which can be efficiently excited by near ultraviolet (UV) light emitting diode (LED) chips. The PL spectrum of Y4Si2O7N2:Ce(3+) shows a broad hump between 380 and 650 nm, assigned to the electron transition from the 4f energy level to different 5d sub levels of the Ce(3+) ions at different Y(3+) sites. The color of the Y4Si2O7N2:Ce(3+) phosphor can shift from blue to green by introducing Tb(3+). In addition, the energy transfer process from Ce(3+) to Tb(3+) in the Y4Si2O7N2 host was investigated and discussed in terms of both the luminescence spectra and decay curves. The energy transfer critical distance has been calculated and evaluated by the concentration quenching method. Therefore, the Ce(3+) and Ce(3+)/Tb(3+)-activated Y4Si2O7N2 phosphors can serve as key materials for phosphor-converted white-light UV-LEDs.

Influence of tellurite on lifetime for samarium doped lanthanum lead borate glass

Science.gov (United States)

Madhu, A.; Eraiah, B.

2018-04-01

Samarium substituted tellurium lanthanum lead borate glass is prepared using melt quenching technique. Luminescence spectra have been recorded upon excitation with 402 nm various transitions from 4G5/2 level, for samarium doped tellurite glasses are studied and also lifetime for all the samples exhibit single exponential behaviour of decay curve. Luminescence spectra of present glasses show quenching effect due to cross-relation channels of samarium ions. The lifetime of glass samples decrease as the tellurite concentration is decreased. So, it evidences that to attain longer lifetime for lasing material one can tune the host by selecting concentration of tellurite.

Decay and Snapback in Superconducting Accelerator Magnets

CERN Document Server

Haverkamp, M

2003-01-01

This thesis deals with the explanation and compensation of the effects 'decay' and 'snapback' in superconducting accelerator magnets, in particular in those used in the new Large Hardron Collider at CERN. During periods of constant magnet excitation, as for example during the injection of particles in the storage ring, the magnetic field in superconducting accelerator magnets shows a decay behavior. As soon as the particles are accelerated, the magnets are ramped, and the magnetic field 'snaps back' to the original hysteresis curve. Decay and snapback affect the beam in the machine and have tobe compensated precisely in order to avoid losses of particles. The research presented in this thesis is a step towards a better understanding of 'decay' and 'snapback' in superconducting particle accelerators. The thesis provides tools for the prediction and compensation of both effects in the magnets, and for the analysis of correlations between different magnet parameters.

Luminescence dating of Netherland's sediments

NARCIS (Netherlands)

Wallinga, J.; Davids, F.; Dijkmans, J.W.A.

2007-01-01

Over the last decades luminescence dating techniques have been developed that allow earth scientists to determine the time of deposition of sediments. In this contribution we revity: 1) the development of the methodology, 2) tests of the reliability of luminescence dating on Netherlands' sediments;

Luminescence enhancement of uranyl ion by benzoic acid in acetonitrile

International Nuclear Information System (INIS)

Satendra Kumar; Maji, S.; Joseph, M.; Sankaran, K.

2014-01-01

Uranyl ion is known for its characteristic green luminescence and therefore luminescence spectroscopy is a suitable technique for characterizing different uranyl species. In aqueous medium, luminescence of uranyl ion is generally weak due to its quenching by water molecules and therefore in order to enhance the luminescence of uranyl ion in aqueous medium, luminescence enhancing reagents such as H 3 PO 4 , H 2 SO 4 , HCIO 4 have been widely used. The other method to enhance the uranyl luminescence is by ligand sensitized luminescence, a method well established for lanthanides. In this work, luminescence of uranyl ion is found to be enhanced by benzoic acid in acetonitrile medium. In aqueous medium benzoic acid does not enhance the uranyl luminescence although it forms 1:1 and 1:2 complexes with uranyl ion. Luminescence spectra of uranyl benzoate revealed that enhancement is due to sensitization of uranyl luminescence by benzoate ions. UV-Vis spectroscopy has been utilized to characterize the specie formed in the in acetonitrile medium. UV-Vis spectroscopy along with luminescence spectra revealed that the specie to be tribenzoate complex of uranyl (UO 2 (C 6 H 5 COO) 3 ) - having D 3 h symmetry. (author)

The TL and room temperature OSL properties of the glow peak at 110 deg. C in natural milky quartz: A case study

International Nuclear Information System (INIS)

Polymeris, George S.; Afouxenidis, Dimitrios; Tsirliganis, Nestor C.; Kitis, George

2009-01-01

The LM-OSL signal of quartz, while measured at room temperature, is dominated by an intermediate, broad and intense OSL component, so that its contribution and general characteristics are derived very accurately. Through a series of dose-response, bleaching and thermal decay at room temperature experiments, in conjunction with curve fitting studies, a component resolved analysis is carried out studying the correlation between this specific component, termed as LM-OSL component C 2 and the 110 deg. C TL glow peak in quartz. The dose-response of these two luminescence components behaves exactly similar being linear at low doses and saturating at almost 100 Gy. Both signals decay exponentially under illumination, providing identical optical detrapping cross-section values. Residual of both luminescence signals after thermal decay at room temperature follows an exponential law, yielding similar mean half-lives. All previous luminescence features provide strong evidence for the electron trap being the same for both the 110 deg. C TL trap and the LM-OSL component C 2 . The results of the present work are very promising and clearly support the possibility of extrapolating the TL pre-dose methodology to the OSL pre-dose effect using only the LM-OSL component C 2

Dissolution glow curve in LLD

International Nuclear Information System (INIS)

Haverkamp, U.; Wiezorek, C.; Poetter, R.

1990-01-01

Lyoluminescence dosimetry is based upon light emission during dissolution of previously irradiated dosimetric materials. The lyoluminescence signal is expressed in the dissolution glow curve. These curves begin, depending on the dissolution system, with a high peak followed by an exponentially decreasing intensity. System parameters that influence the graph of the dissolution glow curve, are, for example, injection speed, temperature and pH value of the solution and the design of the dissolution cell. The initial peak does not significantly correlate with the absorbed dose, it is mainly an effect of the injection. The decay of the curve consists of two exponential components: one fast and one slow. The components depend on the absorbed dose and the dosimetric materials used. In particular, the slow component correlates with the absorbed dose. In contrast to the fast component the argument of the exponential function of the slow component is independent of the dosimetric materials investigated: trehalose, glucose and mannitol. The maximum value, following the peak of the curve, and the integral light output are a measure of the absorbed dose. The reason for the different light outputs of various dosimetric materials after irradiation with the same dose is the differing solubility. The character of the dissolution glow curves is the same following irradiation with photons, electrons or neutrons. (author)

Recent developments in luminescent solar concentrators

Science.gov (United States)

van Sark, W. G. J. H. M.

2014-10-01

High efficiency photovoltaic devices combine full solar spectrum absorption and effective generation and collection of charge carriers, while commercial success depends on cost effectiveness in manufacturing. Spectrum modification using down shifting has been demonstrated in luminescent solar concentrators (LSCs) since the 1970s, as a cheap alternative for standard c-Si technology. LSCs consist of a highly transparent plastic plate, in which luminescent species are dispersed, which absorb incident light and emit light at a red-shifted wavelength, with high quantum efficiency. Material issues have hampered efficiency improvements, in particular re-absorption of light emitted by luminescent species and stability of these species. In this contribution, approaches are reviewed on minimizing re-absorption, which should allow surpassing the 10% luminescent solar concentrator efficiency barrier.

Quartz fast component opticallystimulated luminescence: Towards routine extraction for dating applications

International Nuclear Information System (INIS)

Shen, Zhixiong; Lang, Andreas

2016-01-01

Using an uncontaminated fast component is a key for improving the reliability of quartz OSL dating for many deposits. So far no approach to extract the fast component of quartz OSL has routinely been adopted for dating practice. Key challenges for extracting fast components are (1) the difficulty of finding a unique solution in curve-fitting deconvolution of OSL decay curves and (2) the relatively poor dating precision when using experimental fast component extraction. Here, a simple mathematic solution for fast component extraction is presented that is not relying on curve-fitting deconvolution and can easily be adopted into routine dating practices. By using specifically selected data points from smoothed OSL decay curves, the precision of equivalent doses calculated using the extracted fast component can be improved over equivalent doses calculated using bulk OSL. The fast component extraction is tested on a group of age-constrained samples containing both insufficiently bleached and sufficiently bleached deposits. Fast component OSL ages are as accurate as bulk OSL ages for the sufficiently bleached deposits, but more accurate for samples where bulk OSL is affected by insufficient bleaching. We also demonstrate how using a curve smoothing procedure can improve dating precision in case of both sufficiently and insufficiently bleached deposits. - Highlights: • A simple mathematical method to extract quartz OSL fast component is presented. • The method can be adopted in D_e calculation programs for routine extraction. • The method leads to an increase in accuracy and precision of D_e. • The method works for relatively dim samples with low signal-to-noise ratios.

Review of present trends in luminescence research

International Nuclear Information System (INIS)

Williams, F.; Delaware Univ., Newark

1981-01-01

The difficulties of a comprehensive review of the broad and diverse branches of molecular and solid-state luminescence research are noted. This review is thus limited to selective topics. Some general concepts and trends are then introduced, including: luminescence excitation as a collective excitation of a many-body problem, encompassing in some cases the source and probe in its formulation; continuing trends towards extremal conditions of experiments and towards inhomogeneous and structured materials, from man-made superlattices to biological materials; and increased attention to applications of luminescence research to lamps, displays, solar devices and biological research. Representative recent and new specific research areas include: site selection spectroscopy and 'hole burning'; picosecond delayed coherent anti-Stokes Raman scattering; computer simulation of dynamical processes in luminescence; electron-hole expansion from the Fermi pressure of e-h plasmas; and hot electron phenomena and hot luminescence. Finally some pending problems in luminescence research, such as reconciling the configuration coordinate model and the electronic band theory and clarifying multi-phonon non-radiative processes, are discussed. (orig.)

Development and measurement of luminescence properties of Ce-doped Cs2LiGdBr6 crystals irradiated with X-ray, γ-ray and proton beam

Science.gov (United States)

Jang, Jonghun; Kim, H. J.; Rooh, Gul; Kim, Sunghwan

2017-12-01

The effect of higher Ce-concentration on the luminescence and scintillation properties of Cs2LiGdBr6 single crystals are studied. We used the Bridgman method for the growth of Ce-doped Cs2LiGdBr6 single crystals. Luminescence properties of the grown crystals are measured by X-ray and proton excitations. We measured the pulse height and fluorescence decay time spectra of Cs2LiGdBr6:Ce3+ with a bi-alkali photo multiplier tube (PMT) under γ-ray excitation from 137Cs source. Improvements in the scintillation properties are observed with the increase of Ce-concentration in the lattice. Detailed procedure of the crystal growth is also discussed.

Tunneling decay of self-gravitating vortices

Directory of Open Access Journals (Sweden)

Dupuis Éric

2018-01-01

Full Text Available We investigate tunneling decay of false vortices in the presence of gravity, in which vortices are trapped in the false vacuum of a theory of scalar electrodynamics in three dimensions. The core of the vortex contains magnetic flux in the true vacuum, while outside the vortex is the appropriate topologically nontrivial false vacuum. We numerically obtain vortex solutions which are classically stable; however, they could decay via tunneling. To show this phenomenon, we construct the proper junction conditions in curved spacetime. We find that the tunneling exponent for the vortices is half that for Coleman-de Luccia bubbles and discuss possible future applications.

Luminescence imaging of water during alpha particle irradiation

Science.gov (United States)

Yamamoto, Seiichi; Komori, Masataka; Koyama, Shuji; Toshito, Toshiyuki

2016-05-01

The luminescence imaging of water using the alpha particle irradiation of several MeV energy range is thought to be impossible because this alpha particle energy is far below the Cerenkov-light threshold and the secondary electrons produced in this energy range do not emit Cerenkov-light. Contrary to this consensus, we found that the luminescence imaging of water was possible with 5.5 MeV alpha particle irradiation. We placed a 2 MBq of 241Am alpha source in water, and luminescence images of the source were conducted with a high-sensitivity, cooled charge-coupled device (CCD) camera. We also carried out such imaging of the alpha source in three different conditions to compare the photon productions with that of water, in air, with a plastic scintillator, and an acrylic plate. The luminescence imaging of water was observed from 10 to 20 s acquisition, and the intensity was linearly increased with time. The intensity of the luminescence with the alpha irradiation of water was 0.05% of that with the plastic scintillator, 4% with air, and 15% with the acrylic plate. The resolution of the luminescence image of water was better than 0.25 mm FWHM. Alpha particles of 5.5 MeV energy emit luminescence in water. Although the intensity of the luminescence was smaller than that in air, it was clearly observable. The luminescence of water with alpha particles would be a new method for alpha particle detection and distribution measurements in water.

Luminescence imaging of water during alpha particle irradiation

Energy Technology Data Exchange (ETDEWEB)

Yamamoto, Seiichi, E-mail: s-yama@met.nagoya-u.ac.jp [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine (Japan); Komori, Masataka; Koyama, Shuji [Radiological and Medical Laboratory Sciences, Nagoya University Graduate School of Medicine (Japan); Toshito, Toshiyuki [Department of Proton Therapy Physics, Nagoya Proton Therapy Center, Nagoya City West Medical Center (Japan)

2016-05-21

The luminescence imaging of water using the alpha particle irradiation of several MeV energy range is thought to be impossible because this alpha particle energy is far below the Cerenkov-light threshold and the secondary electrons produced in this energy range do not emit Cerenkov-light. Contrary to this consensus, we found that the luminescence imaging of water was possible with 5.5 MeV alpha particle irradiation. We placed a 2 MBq of {sup 241}Am alpha source in water, and luminescence images of the source were conducted with a high-sensitivity, cooled charge-coupled device (CCD) camera. We also carried out such imaging of the alpha source in three different conditions to compare the photon productions with that of water, in air, with a plastic scintillator, and an acrylic plate. The luminescence imaging of water was observed from 10 to 20 s acquisition, and the intensity was linearly increased with time. The intensity of the luminescence with the alpha irradiation of water was 0.05% of that with the plastic scintillator, 4% with air, and 15% with the acrylic plate. The resolution of the luminescence image of water was better than 0.25 mm FWHM. Alpha particles of 5.5 MeV energy emit luminescence in water. Although the intensity of the luminescence was smaller than that in air, it was clearly observable. The luminescence of water with alpha particles would be a new method for alpha particle detection and distribution measurements in water.

Extended reactivity trace curves for nuclear power control with no power shooting

Energy Technology Data Exchange (ETDEWEB)

Ratemi, W M; Elbuni, M S [Faculty of engineering, Al Fateh universty Tripoli (Libyan Arab Jamahiriya)

1995-10-01

This paper introduces a new concept of reactivity trace curve (RTC) for nuclear power control with no power shooting. The concept is based on recent work of bernard et al. on the dynamic period of nuclear reactors. RTC-method is simulated for both a static effective decay constant corresponding to a one-group delayed neutrons model, and a dynamic effective decay constant corresponding to a six-group delayed neutrons model. A fitting to the RTC of a six-group reactor model resulted in a closed from formula for the RTC that couples the effect of both static and dynamic decay constants. Hence, introducing two `fingerprints` for the reactor in concern to identify a closed from RTC formula capable of controlling the reactor power. Integration of the RTC with control rod integral curves results in the {rho}-z-t diagram. This diagram relates the amount of recommended reactivity (RTC), the position of control rod, and the time required for power control. 8 figs.

Extended reactivity trace curves for nuclear power control with no power shooting

International Nuclear Information System (INIS)

Ratemi, W. M.; Elbuni, M. S.

1995-01-01

This paper introduces a new concept of reactivity trace curve (RTC) for nuclear power control with no power shooting. The concept is based on recent work of bernard et al. on the dynamic period of nuclear reactors. RTC-method is simulated for both a static effective decay constant corresponding to a one-group delayed neutrons model, and a dynamic effective decay constant corresponding to a six-group delayed neutrons model. A fitting to the RTC of a six-group reactor model resulted in a closed from formula for the RTC that couples the effect of both static and dynamic decay constants. Hence, introducing two 'fingerprints' for the reactor in concern to identify a closed from RTC formula capable of controlling the reactor power. Integration of the RTC with control rod integral curves results in the ρ-z-t diagram. This diagram relates the amount of recommended reactivity (RTC), the position of control rod, and the time required for power control. 8 figs

Luminescence and scintillation properties of Rb2HfCl6 crystals

International Nuclear Information System (INIS)

Saeki, Keiichiro; Wakai, Yuki; Fujimoto, Yutaka; Koshimizu, Masanori; Asai, Keisuke; Yanagida, Takayuki; Nakauchi, Daisuke

2016-01-01

We developed a scintillator based on a Rb 2 HfCl 6 crystal as a ternary halide crystal with intrinsic luminescence. In the photoluminescence spectra, two emission bands are observed at 383 and 434 nm. The 434 nm emission band for Rb 2 HfCl 6 may be attributed to [HfCl 6 ] 2- complex ion or [ZrCl 6 ] 2- impurity, since the Rb 2 HfCl 6 contained Zr as impurity at 0.62 mol %. The radioluminescence band is observed at 420 nm and can be attributed to the same origin as the photoluminescence band at 434 nm. The scintillation decay-time constants were 0.84 and 5.4 μs. The light yield was estimated to be 24,100 photons/MeV. (author)

Towards Luminescence Dating Of Mosaic Glass

Science.gov (United States)

Galli, A.; Martini, M.; Sibila, E.; Villa, I.

The possibility of dating archaeological glass by means of luminescent techniques has been investigated in recent years, despite the difficulties of this application, mainly linked to the amorphous structure of the material. We focused in particular on mosaic glass, after the encouraging results obtained on byzantine and medieval samples. Further studies were devoted to the comprehension of the luminescent mechanisms in silica glasses, and to the investigation of the relationships between luminescence, colouring or opacifier ions and crystalline phase of the vitreous matrix. The results of a study on the dosimetric characteristics of thermoluminescence (TL) and Optically Stimulated Luminescence (OSL) of a few medieval blue-green mosaic glasses from the San Lorenzo church (Milan) are presented, and the experimental protocols established to identify their suitability for dating are discussed.

MeV ion irradiation effects on the luminescence properties of Si-implanted SiO{sub 2}-thin films

Energy Technology Data Exchange (ETDEWEB)

Chulapakorn, T.; Primetzhofer, D. [Uppsala University, Department of Physics and Astronomy, P.O. Box 516, 751 20 Uppsala (Sweden); Sychugov, I.; Suvanam, S.S.; Linnros, J.; Hallen, A. [Royal Institute of Technology (KTH), School of Information and Communication Technology, P.O. Box Electrum 229, 164 40 Kista (Sweden)

2016-12-15

The effects of MeV heavy ion irradiation at varying fluence and flux on excess Si, introduced in SiO{sub 2} by keV ion implantation, are investigated by photoluminescence (PL). From the PL peak wavelength (λ) and decay lifetime (τ), two PL sources are distinguished: (i) quasi-direct recombination of excitons of Si-nanoparticles (SiNPs), appearing after thermal annealing (λ > 720 nm, τ ∝ μs), and (ii) fast-decay PL, possibly due to oxide-related defects (λ ∝ 575-690 nm, τ ∝ ns). The fast-decay PL (ii) observed before and after ion irradiation is induced by ion implantation. It is found that this fast-decay luminescence decreases for higher irradiation fluence of MeV heavy ions. After thermal annealing (forming SiNPs), the SiNP PL is reduced for samples irradiated by MeV heavy ions but found to stabilize at higher level for higher irradiation flux; the (ii) band vanishes as a result of annealing. The results are discussed in terms of the influence of electronic and nuclear stopping powers. (copyright 2016 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

Charge recombination processes in minerals studied using optically stimulated luminescence and time-resolved exo-electrons

DEFF Research Database (Denmark)

Tsukamoto, Sumiko; Murray, Andrew; Ankjærgaard, Christina

2010-01-01

electron concentration in the conduction band. In this study, TR-OSE and time-resolved optically stimulated luminescence (TR-OSL) were measured for the first time using quartz, K-feldspar and NaCl by stimulating the samples using pulsed blue LEDs at different temperatures between 50 and 250 °C after beta...... irradiation and preheating to 280 °C. The majority of TR-OSE signals from all the samples decayed much faster than TR-OSL signals irrespective of the stimulation temperatures. This suggests that the lifetime of OSL in these dosimeters arises mainly from the relaxation of an excited state of the recombination...

Luminescence properties of Yb:Nd:Tm:KY{sub 3}F{sub 10} nanophosphor and thermal treatment effects

Energy Technology Data Exchange (ETDEWEB)

Gomes, Laércio, E-mail: lgomes@ipen.br [Centro de Lasers e Aplicações, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Butantã, P.O. Box 11049, São Paulo, SP o5422-970 (Brazil); Linhares, Horácio Marconi da Silva M.D. [Centro de Lasers e Aplicações, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Butantã, P.O. Box 11049, São Paulo, SP o5422-970 (Brazil); Ichikawa, Rodrigo Uchida; Martinez, Luis Gallego [Departamento de Ciências dos Materiais, Instituto de Pesquisas Energéticas e Nucleares (Brazil); Ranieri, Izilda Marcia [Centro de Lasers e Aplicações, Instituto de Pesquisas Energéticas e Nucleares, IPEN-CNEN/SP, Butantã, P.O. Box 11049, São Paulo, SP o5422-970 (Brazil)

2015-01-15

In this work, we present the spectroscopic properties of KY{sub 3}F{sub 10} (KY3F) nanocrystals activated with thulium and codoped with ytterbium and neodymium ions. The most important processes that lead to the thulium upconversion emissions in the blue region were identified. A time-resolved luminescence spectroscopy technique was employed to measure the luminescence decays and to determine the most important mechanisms involved in the upconversion process that populates {sup 1}G{sub 4} (Tm{sup 3+}) excited states. Analysis of the energy-transfer processes dynamics using selective pulsed-laser excitations in Yb:Nd:Tm, Nd:KY3F nanocrystals shows that the direct energy transfer from Nd{sup 3+} to Tm{sup 3+} ions is the mechanism responsible for the 78% of the blue upconversion luminescence in the Yb:Nd:Tm:KY3F when compared with the Yb:Nd:Tm:KY3F bulk crystal for an laser excitation at 802 nm. An investigation of the {sup 1}G{sub 4} level luminescence kinetic of Tm{sup 3+} in Yb/Nd/Tm system revealed that the luminescence efficiency ({sup 1}G{sub 4}) starts with a very low value (0.38%) for the synthesized nanocrystal (as grown) and strongly increases to 97% after thermal treatment at 550 °C for 6 h under argon flow. As a consequence of the thermal treatment at T=550 °C, the contributions of the (Nd×Tm) (Up{sub 1}) and (Nd×Yb×Tm) (Up{sub 2}) upconversion processes to the {sup 1}G{sub 4} luminescence are 33% (Up{sub 1}) and 67% for Up{sub 2}. Up{sub 2} process represented by Nd{sup 3+} ({sup 4}F{sub 3/2})→Yb{sup 3+} ({sup 2}F{sub 7/2}) followed by Yb{sup 3+} ({sup 2}F{sub 5/2})→Tm ({sup 3}H{sub 4})→Tm{sup 3+} ({sup 1}G{sub 4}) was previously reported as the main mechanism to produce the blue luminescence in Yb:Nd:Tm:YLiF{sub 4} and KY{sub 3}F{sub 10} bulk crystals. Results of X-ray diffraction analysis of nanopowder using the Rietveld method reveled that crystallite sizes remain unchanged (12–14 nm) after thermal treatments with T≤400 °C, while the

Decay correction methods in dynamic PET studies

International Nuclear Information System (INIS)

Chen, K.; Reiman, E.; Lawson, M.

1995-01-01

In order to reconstruct positron emission tomography (PET) images in quantitative dynamic studies, the data must be corrected for radioactive decay. One of the two commonly used methods ignores physiological processes including blood flow that occur at the same time as radioactive decay; the other makes incorrect use of time-accumulated PET counts. In simulated dynamic PET studies using 11 C-acetate and 18 F-fluorodeoxyglucose (FDG), these methods are shown to result in biased estimates of the time-activity curve (TAC) and model parameters. New methods described in this article provide significantly improved parameter estimates in dynamic PET studies

Luminescent amine sensor based on europium(III) chelate.

Science.gov (United States)

Petrochenkova, Nataliya V; Mirochnik, Anatolii G; Emelina, Tatyana B; Sergeev, Alexander A; Leonov, Andrei A; Voznesenskii, Sergey S

2018-07-05

The effect of methylamine vapor on luminescence of Eu(III) tris-benzoylacetonate (I) immobilized in thin-layer chromatography plates has been investigated. It has been revealed that interaction of I with analyte vapor results in increase of the intensity of Eu(III) luminescence. The mechanism of the effect of methylamine vapors on intensification of the Eu(III) luminescence has been suggested using the data of IR spectroscopy and quantum chemistry calculations. The mechanism of luminescence sensitization consists in bonding of an analyte molecule with a water molecule into the coordination sphere of Eu(III). As a result, the bond of a water molecule with the luminescence centre weakens, rigid structural fragment including europium ion, water and methylamine molecules forms. The presence of such fragment must naturally promote decrease of influence of OH-vibrations on luminescence of the complex I. Copyright © 2018 Elsevier B.V. All rights reserved.

Silica nanoparticles with a substrate switchable luminescence

International Nuclear Information System (INIS)

Bochkova, O D; Mustafina, A R; Fedorenko, S V; Konovalov, A I

2011-01-01

Silica nanoparticles with visible (Tb and Ru doped), near IR (Yb doped) and dual visible-near IR luminescence (Ru-Yb doped) were obtained by reverse w/o microemulsion procedure. Plenty of luminescent complexes (from 4900 to 10000) encapsulated into each nanoparticle ensures the intensive luminescence of nanoparticles and their applicability as biomarkers. The silica surface decoration by definite anchor groups is the required step for the gaining to these nanoparticles marking and sensing functions. Thus covalent and non-covalent surface modification of these nanoparticles was developed to provide the binding with biotargets and sensing of anions. The dicationic surfactant coating of negatively charged Tb(III)-TCAS doped silica nanoparticles was chosen as the basis for the anion responsible system. The reversible insertion of the quenching anions (namely phenol red) into the surfactant based layer at the surface of luminescent nanoparticles switches off the Tb-centered luminescence. In turn the reversible reestablishment of the luminescence results from the competitive insertion of the non-quenching anions into the surfactant layer at the silica/water interface. The hydrophobic anions exemplified by dodecylsulfates versus hydrophilic ones (hydrophosphates) are preferable in the competition with phenol red anions.

Jellium-model calculation for monomer and dimer decays of some potassium clusters

International Nuclear Information System (INIS)

Saito, Susumu; Cohen, M.L.; Lawrence Berkeley Lab., CA

1989-01-01

We have studied several decay processes of potassium clusters and found that a dimer-decay mechanism can explain the observed lowest abundance of K 10 in the K n mass spectra. Total-energy curves for decay processes are calculated using a jellium-background model for positive-ion cores and the local-spin-density-functional approximation for valence electrons. The energy-barrier height for a dimer decay of K 10 from the energy-minimum point is found to be 0.18 eV, which is a reasonable magnitude for the decay to take place thermally in the experiment. The monomer decay of K 9 and the dimer decay of K 11 , which are expected to be the most favorable decays of K 9 and K 11 , are found to have high barriers. Monomer and dimer decays of K 8 are also studied and the monomer decay is found to be more favorable, in accord with the high-nozzle-temperature mass spectrum. (orig.)

Linking fluorescence induction curve and biomass in herbicide screening.

Science.gov (United States)

Christensen, Martin G; Teicher, Harald B; Streibig, Jens C

2003-12-01

A suite of dose-response bioassays with white mustard (Sinapis alba L) and sugar beet (Beta vulgaris L) in the greenhouse and with three herbicides was used to analyse how the fluorescence induction curves (Kautsky curves) were affected by the herbicides. Bentazone, a photosystem II (PSII) inhibitor, completely blocked the normal fluorescence decay after the P-step. In contrast, fluorescence decay was still obvious for flurochloridone, a PDS inhibitor, and glyphosate, an EPSP inhibitor, which indicated that PSII inhibition was incomplete. From the numerous parameters that can be derived from OJIP-steps of the Kautsky curve the relative changes at the J-step [Fvj = (Fm - Fj)/Fm] was selected to be a common response parameter for the herbicides and yielded consistent dose-response relationships. Four hours after treatment, the response Fvj on the doses of bentazone and flurochloridone could be measured. For glyphosate, the changes of the Kautsky curve could similarly be detected 4 h after treatment in sugar beet, but only after 24 hs in S alba. The best prediction of biomass in relation to Fvj was found for bentazone. The experiments were conducted between May and August 2002 and showed that the ambient temperature and solar radiation in the greenhouse could affect dose-response relationships. If the Kautsky curve parameters should be used to predict the outcome of herbicide screening experiments in the greenhouse, where ambient radiation and temperature can only partly be controlled, it is imperative that the chosen fluorescence parameters can be used to predict accurately the resulting biomass used in classical bioassays.

Quenching methods for background reduction in luminescence-based probe-target binding assays

Energy Technology Data Exchange (ETDEWEB)

Cai, Hong [Los Alamos, NM; Goodwin, Peter M [Los Alamos, NM; Keller, Richard A [Los Alamos, NM; Nolan, Rhiannon L [Santa Fe, NM

2007-04-10

Background luminescence is reduced from a solution containing unbound luminescent probes, each having a first molecule that attaches to a target molecule and having an attached luminescent moiety, and luminescent probe/target adducts. Quenching capture reagent molecules are formed that are capable of forming an adduct with the unbound luminescent probes and having an attached quencher material effective to quench luminescence of the luminescent moiety. The quencher material of the capture reagent molecules is added to a solution of the luminescent probe/target adducts and binds in a proximity to the luminescent moiety of the unbound luminescent probes to quench luminescence from the luminescent moiety when the luminescent moiety is exposed to exciting illumination. The quencher capture reagent does not bind to probe molecules that are bound to target molecules and the probe/target adduct emission is not quenched.

Dynamic View on Nanostructures: A Technique for Time Resolved Optical Luminescence Using Synchrotron Light Pulses at SRC, APS, and CLS

International Nuclear Information System (INIS)

Heigl, F.; Jurgensen, A.; Zhou, X.-T.; Lam, S.; Murphy, M.; Ko, J.Y.P.; Sham, T.K.; Rosenberg, R.A.; Gordon, R.; Brewe, D.; Regier, T.; Armelao, L.

2007-01-01

We present an experimental technique using the time structure of synchrotron radiation to study time resolved X-ray excited optical luminescence. In particular we are taking advantage of the bunched distribution of electrons in a synchrotron storage ring, giving short x-ray pulses (10-10 2 picoseconds) which are separated by non-radiating gaps on the nano- to tens of nanosecond scale - sufficiently wide to study a broad range of optical decay channels observed in advanced nanostructured materials.

Hardness ratio evolutionary curves of gamma-ray bursts expected by the curvature effect

International Nuclear Information System (INIS)

Qin, Y.-P.; Su, C.-Y.; Fan, J. H.; Gupta, A. C.

2006-01-01

We have investigated the gamma-ray bursts (GRBs) pulses with a fast rise and an exponential decay phase, assumed to arise from relativistically expending fireballs, and found that the curvature effect influences the evolutionary curve of the corresponding hardness ratio (hereafter HRC). We find, due to the curvature effect, the evolutionary curve of the pure hardness ratio (when the background count is not included) would peak at the very beginning of the curve, and then would undergo a drop-to-rise-to-decay phase. In the case of the raw hardness ratio (when the background count is included), the curvature effect would give rise to several types of evolutionary curve, depending on the hardness of a burst. For a soft burst, an upside down pulse of its raw HRC would be observed; for a hard burst, its raw HRC shows a pulselike profile with a sinkage in its decaying phase; for a very hard burst, the raw HRC possesses a pulselike profile without a sinkage in its decaying phase. For a pulselike raw HRC as shown in the case of the hard and very hard bursts, its peak would appear in advance of that of the corresponding light curve, which was observed previously in some GRBs. For illustration, we have studied here the HRC of GRB 920216, GRB 920830, and GRB 990816 in detail. The features of the raw HRC expected in the hard burst are observed in these bursts. A fit to the three bursts shows that the curvature effect alone could indeed account for the predicted characteristics of HRCs. In addition, we find that the observed hardness ratio tends to be harder at the beginning of the pulses than what the curvature effect could predict and be softer at the late time of the pulses. We believe this is an evidence showing the existence of intrinsic hard-to-soft radiation which might be due to the acceleration-to-deceleration mode of shocks

SPOTTED STAR LIGHT CURVES WITH ENHANCED PRECISION

International Nuclear Information System (INIS)

Wilson, R. E.

2012-01-01

The nearly continuous timewise coverage of recent photometric surveys is free of the large gaps that compromise attempts to follow starspot growth and decay as well as motions, thereby giving incentive to improve computational precision for modeled spots. Due to the wide variety of star systems in the surveys, such improvement should apply to light/velocity curve models that accurately include all the main phenomena of close binaries and rotating single stars. The vector fractional area (VFA) algorithm that is introduced here represents surface elements by small sets of position vectors so as to allow accurate computation of circle-triangle overlap by spherical geometry. When computed by VFA, spots introduce essentially no noticeable scatter in light curves at the level of one part in 10,000. VFA has been put into the Wilson-Devinney light/velocity curve program and all logic and mathematics are given so as to facilitate entry into other such programs. Advantages of precise spot computation include improved statistics of spot motions and aging, reduced computation time (intrinsic precision relaxes needs for grid fineness), noise-free illustration of spot effects in figures, and help in guarding against false positives in exoplanet searches, where spots could approximately mimic transiting planets in unusual circumstances. A simple spot growth and decay template quantifies time profiles, and specifics of its utilization in differential corrections solutions are given. Computational strategies are discussed, the overall process is tested in simulations via solutions of synthetic light curve data, and essential simulation results are described. An efficient time smearing facility by Gaussian quadrature can deal with Kepler mission data that are in 30 minute time bins.

Decay Power Calculation for Safety Analysis of Innovative Reactor Systems

International Nuclear Information System (INIS)

Shwageraus, E.; Fridman, E.

2008-01-01

In this work, we verified the decay heat calculation capabilities of BGCore computer code system developed recently at Ben-Gurion University. Decay power was calculated for a typical UO 2 fuel in Pressurized Water Reactor environment using BGCore code and using procedure prescribed by the ANS/ANSI-2005 standard. Very good agreement between the two methods was obtained. Once BGCore calculation capabilities were verified, we calculated decay power as a function of time after shutdown for various reactors with innovative fuels, for which no standard procedure is currently available. Notable differences were observed for decay power of the advanced reactors as compared with conventional UO 2 LWR. The observed differences suggest that the design of new reactors safety systems must be based on corresponding decay power curves for each individual case in order to assure the desired performance of such systems. (authors)

Data reading with the aid of one-photon and two-photon luminescence in three-dimensional optical memory devices based on photochromic materials

International Nuclear Information System (INIS)

Akimov, Denis A; Zheltikov, Aleksei M; Koroteev, Nikolai I; Naumov, A N; Fedotov, Andrei B; Magnitskiy, Sergey A; Sidorov-Biryukov, D A; Sokolyuk, N T

1998-01-01

The problem of nondestructive reading of the data stored in the interior of a photochromic sample was analysed. A comparison was made of the feasibility of reading based on one-photon and two-photon luminescence. A model was proposed for the processes of reading the data stored in photochromic molecules with the aid of one-photon and two-photon luminescence. In addition to photochromic transitions, account was taken of the transfer of populations between optically coupled transitions in molecules under the action of the exciting radiation. This model provided a satisfactory description of the kinetics of decay of the coloured form of bulk samples of spiropyran and made it possible to determine experimentally the quantum yield of the reverse photoreaction as well as the two-photon absorption cross section of the coloured form. Measurements were made of the characteristic erasure times of the data stored in a photochromic medium under one-photon and two-photon luminescence reading conditions. It was found that the use of two-photon luminescence made it possible to enhance considerably the contrast and localisation of the optical data reading scheme in three-dimensional optical memory devices. The experimental results were used to estimate the two-photon absorption cross section of the coloured form of a sample of indoline spiropyran in a polymethyl methacrylate matrix. (laser applications and other topics in quantum electronics)

Triggering on hadronic tau decays: ATLAS meets the challenge

CERN Document Server

Scarcella, M J; The ATLAS collaboration

2011-01-01

Hadronic tau decays play a crucial role in taking Standard Model measurements as well as in the search for physics beyond the Standard Model. However, hadronic tau decays are difficult to identify and trigger on due to their resemblance to QCD jets. Given the large production cross section of QCD processes, designing and operating a trigger system with the capability to efficiently select hadronic tau decays, while maintaining the rate within the bandwidth limits, is a difficult challenge. This contribution will summarize the status and performance of the ATLAS tau trigger system during the 2011 data taking period, emphasizing the key elements of the online selection. Different methods that have been explored to obtain the trigger efficiency curves from data will be shown. Finally, the status of the measurements, which include hadronic tau decays in the final state, will be summarized. In light of the vast statistics collected in 2011, future prospects for triggering on hadronic tau decays in this exciting ne...

Optical and luminescence properties of Dy3+ doped sodium silicate glass

Science.gov (United States)

Srisittipokakun, N.; Kaewkhao, J.

2017-07-01

The aim of the present work is to study the optical and luminescence properties of Dy2O3 doped Na2O-BaO-Bi2O3-SiO2 glasses. The Dy3+ ion is chosen as dopant because it emits three visible bands, blue (470-485 nm; 4F9/2→6H15/2), yellow (570-580 nm; 4F9/2→6H13/2) and red (640-655 nm; 4F9/2→6H11/2) luminescence and finds its applications in the fields of laser, white LEDs, telecommunication technology and display devices. NaBaBiSiDy glasses with the compositions of (30-x)SiO2: 10Bi2O3: 30Na2O: 30BaO: xDy2O3 where x=0.0, 0.1, 0.5, 1.0, 1.5 and 2.0 mol% were prepared by melt-quenching technique and characterized by using density, optical absorption photoluminescence (PL) and decay rate measurements as function of different concentrations. The density (ρ), molar volume (VM) and refractive index obtained were found to increase with increase in the concentration of Dy2O3 in the glass matrix. The chromaticity coordinates were calculated from emission spectra and analyzed with CIE color diagram and appear in the white light region under ultraviolet excitation.

Leptogenesis and gravity: Baryon asymmetry without decays

Energy Technology Data Exchange (ETDEWEB)

McDonald, J.I., E-mail: pymcdonald@swansea.ac.uk; Shore, G.M., E-mail: g.m.shore@swansea.ac.uk

2017-03-10

A popular class of theories attributes the matter-antimatter asymmetry of the Universe to CP-violating decays of super-heavy BSM particles in the Early Universe. Recently, we discovered a new source of leptogenesis in these models, namely that the same Yukawa phases which provide the CP violation for decays, combined with curved-spacetime loop effects, lead to an entirely new gravitational mechanism for generating an asymmetry, driven by the expansion of the Universe and independent of the departure of the heavy particles from equilibrium. In this Letter, we build on previous work by analysing the full Boltzmann equation, exploring the full parameter space of the theory and studying the time-evolution of the asymmetry. Remarkably, we find regions of parameter space where decays play no part at all, and where the baryon asymmetry of the Universe is determined solely by gravitational effects.

Apparatus for reducing solvent luminescence background emissions

Energy Technology Data Exchange (ETDEWEB)

Affleck, Rhett L. (Los Alamos, NM); Ambrose, W. Patrick (Los Alamos, NM); Demas, James N. (Charlottesville, VA); Goodwin, Peter M. (Jemez Springs, NM); Johnson, Mitchell E. (Pittsburgh, PA); Keller, Richard A. (Los Alamos, NM); Petty, Jeffrey T. (Los Alamos, NM); Schecker, Jay A. (Sante Fe, NM); Wu, Ming (Los Alamos, NM)

1998-01-01

The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

Phonon transport across nano-scale curved thin films

Energy Technology Data Exchange (ETDEWEB)

Mansoor, Saad B.; Yilbas, Bekir S., E-mail: bsyilbas@kfupm.edu.sa

2016-12-15

Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.

Phonon transport across nano-scale curved thin films

International Nuclear Information System (INIS)

Mansoor, Saad B.; Yilbas, Bekir S.

2016-01-01

Phonon transport across the curve thin silicon film due to temperature disturbance at film edges is examined. The equation for radiative transport is considered via incorporating Boltzmann transport equation for the energy transfer. The effect of the thin film curvature on phonon transport characteristics is assessed. In the analysis, the film arc length along the film centerline is considered to be constant and the film arc angle is varied to obtain various film curvatures. Equivalent equilibrium temperature is introduced to assess the phonon intensity distribution inside the curved thin film. It is found that equivalent equilibrium temperature decay along the arc length is sharper than that of in the radial direction, which is more pronounced in the region close to the film inner radius. Reducing film arc angle increases the film curvature; in which case, phonon intensity decay becomes sharp in the close region of the high temperature edge. Equivalent equilibrium temperature demonstrates non-symmetric distribution along the radial direction, which is more pronounced in the near region of the high temperature edge.

Optically stimulated luminescence (OSL) and some other luminescence images from granite slices exposed with radiations

International Nuclear Information System (INIS)

Hashimoto, T.; Notoya, S.; Ojima, T.; Hoteida, M.

1995-01-01

Optically stimulated luminescence (OSL) images of some X- and γ-irradiated granite slices were obtained using photon detection through a 570 nm bandpass filter with diode-laser excitation of 910 nm. Alternative photo-induced phosphorescence (PIP) images, which were colour photographed immediately after the sunlight exposure of slice samples, were also found to be helpful in the observation of the luminescence properties and to filter selection for OSL measurements. These OSL and PIP images were compared with some other colour luminescence images, including thermoluminescence images (TLCI) and after-glow images (AGCI). It was obvious that there exists a variety of coloured emissions derived mainly from feldspar constituents and these were found to be dependent on the geological history or metamorphism of the granites. (Author)

Time-resolved luminescence spectroscopy of trace uranyl in wet sand

International Nuclear Information System (INIS)

Freed, D.

1993-01-01

The objective of the project was to develop a technique to observe and characterize the behaviour of uranium in unsaturated groundwater flow systems, particularly with regard to unstable ''fingered'' flow, which could drastically reduce time of travel. The actual experimental work described was a study of the feasibility of detecting uranyl at the parts-per-billion level in aqueous solution by means of its luminescence spectrum. A high-power UV laser was used to excite aqueous uranyl in a wet sand mixture; the characteristic green phosphorescence emitted in the decay transition was detected by a photomultiplier tube; and the amplified signal was sent to an oscilloscope in communication with Macintosh data acquisition software. At the time of the conference, a more sophisticated sample configuration for imaging the flow of uranyl was already under development. 5 refs., 3 figs

Time-resolved luminescence spectroscopy of trace uranyl in wet sand

Energy Technology Data Exchange (ETDEWEB)

Freed, D [Massachusetts Inst. of Tech., Cambridge, MA (United States)

1994-12-31

The objective of the project was to develop a technique to observe and characterize the behaviour of uranium in unsaturated groundwater flow systems, particularly with regard to unstable ``fingered`` flow, which could drastically reduce time of travel. The actual experimental work described was a study of the feasibility of detecting uranyl at the parts-per-billion level in aqueous solution by means of its luminescence spectrum. A high-power UV laser was used to excite aqueous uranyl in a wet sand mixture; the characteristic green phosphorescence emitted in the decay transition was detected by a photomultiplier tube; and the amplified signal was sent to an oscilloscope in communication with Macintosh data acquisition software. At the time of the conference, a more sophisticated sample configuration for imaging the flow of uranyl was already under development. 5 refs., 3 figs.

Modern luminescence spectroscopy of minerals and materials

CERN Document Server

Gaft, Michael; Panczer, Gerard

2005-01-01

Luminescence Spectroscopy of Minerals and Materials presents an overview of the general concepts in luminescence spectroscopy as well as experimental methods and their interpretation. Special emphasis is laid on the fluorescence lifetime and the determination of time-resolved spectra. This method enables the exposure of new luminescence in minerals previously hidden by more intensive centers. Specialists in the fields of solid state physics, chemistry and spectroscopy will find a wealth of new information in this unique book.

MOlecular MAterials Property Prediction Package (MOMAP) 1.0: a software package for predicting the luminescent properties and mobility of organic functional materials

Science.gov (United States)

Niu, Yingli; Li, Wenqiang; Peng, Qian; Geng, Hua; Yi, Yuanping; Wang, Linjun; Nan, Guangjun; Wang, Dong; Shuai, Zhigang

2018-04-01

MOlecular MAterials Property Prediction Package (MOMAP) is a software toolkit for molecular materials property prediction. It focuses on luminescent properties and charge mobility properties. This article contains a brief descriptive introduction of key features, theoretical models and algorithms of the software, together with examples that illustrate the performance. First, we present the theoretical models and algorithms for molecular luminescent properties calculation, which includes the excited-state radiative/non-radiative decay rate constant and the optical spectra. Then, a multi-scale simulation approach and its algorithm for the molecular charge mobility are described. This approach is based on hopping model and combines with Kinetic Monte Carlo and molecular dynamics simulations, and it is especially applicable for describing a large category of organic semiconductors, whose inter-molecular electronic coupling is much smaller than intra-molecular charge reorganisation energy.

Photoluminescence spectroscopies and temperature-dependent luminescence of Mn{sup 4+} in BaGe{sub 4}O{sub 9} phosphor

Energy Technology Data Exchange (ETDEWEB)

Zhang, Shaoan; Hu, Yihua, E-mail: huyh@gdut.edu.cn

2016-09-15

New non-rare-earth red phosphor BaGe{sub 4}O{sub 9}:Mn{sup 4+} was prepared successfully via the traditional solid state reaction method. The luminescent performance was investigated by the steady-state photoluminescence (PL) and temperature-dependent PL/decay measurements. The excitation band of BaGe{sub 4}O{sub 9}:Mn{sup 4+} phosphor covers a broad spectral region from 250 nm to 500 nm, which matches well with the commercial near-UV and blue LEDs. The concentration quenching of Mn{sup 4+} in BaGe{sub 4}O{sub 9}:Mn{sup 4+} occurs at a low content of 0.5% due to the dipole–dipole interaction. We gained insight into the temperature-dependent relative emission intensity of BaGe{sub 4}O{sub 9}:Mn{sup 4+} phosphor, and determined the luminescence quenching temperature and the activation energy for thermal quenching (∆E) to be ~150 K and ~0.17 eV, respectively.

Red luminescence from Eu3+-doped TeO2-WO3-GeO2 glasses for solid state lasers

Science.gov (United States)

Subrahmanyam, Tallam; Gopal, Kotalo Rama; Suvarna, Reniguntla Padma; Jamalaiah, Bungala Chinna

2018-05-01

Eu3+-doped oxyfluoro tellurite (TWGEu) glasses were prepared by conventional melt quenching method. The optical band gap energy and covalence between Eu3+ and O2-/F- ions were determined from optical absorption spectra. Using the 5D0 → 7F1,2,4 emission transitions, the Ω2 and Ω4 intensity parameters were determined. These intensity parameters were used to evaluate the radiative parameters such as emission probability rate (AR), luminescence branching ratio (βR) and radiative life time (τR) of 5D0 → 7FJ transitions. The laser characteristic parameters such as stimulated emission cross-section, gain bandwidth and quantum efficiency were determined. The luminescence decay profiles of 5D0 emission level were well fitted to single exponential function for all the concentrations. The experimental results show that the 0.5 mol% of Eu3+-doped TWGEu glass could be the best choice to design red laser sources.

Sample dependent correlation between TL and LM-OSL in Al2O3:C

International Nuclear Information System (INIS)

Dallas, G.I.; Polymeris, G.S.; Stefanaki, E.C.; Afouxenidis, D.; Tsirliganis, N.C.; Kitis, G.

2008-01-01

Al 2 O 3 :C single crystals are known to exhibit different, sample dependent, glow-curve shapes. The relation between the Thermoluminescence (TL) traps and the linear modulated optically stimulation luminescence (LM-OSL) traps is of high importance. In the present work a correlation study is attempted using 23 single crystals with dimensions between 400 and 500μm. The correlation study involved two steps. In the first step, both TL glow curves and LM-OSL decay curves are deconvoluted and a one-to-one correlation between TL peaks and LM-OSL components is attempted. In the second step the TL glow-curves are corrected for thermal quenching, the corrected curves are deconvoluted and a new correlation between TL and LM-OSL individual components is performed

Decay Power Calculation for Safety Analysis of Innovative Reactor Systems

Energy Technology Data Exchange (ETDEWEB)

Shwageraus, E.; Fridman, E. [Department of Nuclear Engineering, Ben-Gurion University of the Negev Beer-Sheva 84105 (Israel)

2008-07-01

In this work, we verified the decay heat calculation capabilities of BGCore computer code system developed recently at Ben-Gurion University. Decay power was calculated for a typical UO{sub 2} fuel in Pressurized Water Reactor environment using BGCore code and using procedure prescribed by the ANS/ANSI-2005 standard. Very good agreement between the two methods was obtained. Once BGCore calculation capabilities were verified, we calculated decay power as a function of time after shutdown for various reactors with innovative fuels, for which no standard procedure is currently available. Notable differences were observed for decay power of the advanced reactors as compared with conventional UO{sub 2} LWR. The observed differences suggest that the design of new reactors safety systems must be based on corresponding decay power curves for each individual case in order to assure the desired performance of such systems. (authors)

Photoluminescence, reddish orange long persistent luminescence and photostimulated luminescence properties of praseodymium doped CdGeO3 phosphor

International Nuclear Information System (INIS)

Jin, Yahong; Hu, Yihua; Chen, Li; Fu, Yinrong; Mu, Zhongfei; Wang, Tao; Lin, Jun

2014-01-01

Highlights: • A novel phosphor CdGeO 3 :Pr 3+ was synthesized successfully. • The persistent luminescence properties of CdGeO 3 :Pr 3+ were studied. • The photostimulated luminescence properties of CdGeO 3 :Pr 3+ were investigated. • The persistent and photostimulated luminescence mechanisms were discussed in detail. - Abstract: Praseodymium doped CdGeO 3 phosphors were prepared successfully by a conventional high temperature solid-state reaction method. It showed reddish orange long persistent luminescence (LPL) after the short UV-irradiation. The reddish orange photostimulated luminescence (PSL) was also observed upon near infrared stimulation at 980 nm after per-exposure into UV light. The origin of LPL and PSL was identified with the emission from Pr 3+ ions with the aid of traps in host lattice. The optimal concentration of Pr 3+ ions for the brightest photoluminescence (PL) emission and the best LPL characteristic were experimentally to be about 3% and 0.5 mol%, respectively. The trapping and de-trapping processes of charge carriers between shallower and deep traps were illustrated. A model was proposed on the basis of experimental results to study the mechanisms of LPL and PSL

Detection of food irradiation with luminescence methods

International Nuclear Information System (INIS)

Anderle, H.

1997-06-01

Food irradiation is applied as method for the preservation of foods, the prevention of food spoilage and the inhibition of food-borne pathogens. Doses exceeding 10 kGy (10 kJ/kg) are not recommended by the WHO. The different legislation requires methods for the detection and the closimetry of irradiated foods. Among the physical methods based on the radiation-induced changes in inorganic, nonhygroscopic crystalline solids are thermoluminescence (TL), photostimulated luminescence (PSL) and lyoluminescence (LL) measurement. The luminescence methods were tested on natural minerals. Pure quartz, feldspars, calcite, aragonite and dolomite of known origin were irradiated, read out and analyzed to determine the influence of luminescence-activators and deactivators. Carbonate minerals show an orange-red TL easily detectable by blue-sensitive photomultiplier tubes. TIL-inactive carbonate samples may be identified by a lyoluminescence method using the reaction of trapped irradiation-generated charge carriers with the solvent during crystal-lattice breakup. The fine-ground mineral is dissolved in an alkaline complexing agent/chemiluminescence sensitizer/chemiluminescence catalyst (EDTA/luminol/hemin) reagent mixture. The TL and PSL of quartz is too weak to contribute a significant part for the corresponding signals in polymineral dust. Alkali and soda feldspar show intense TL and PSL. The temperature maxima in the TL glow curves allow a clear distinction. PSL does not give this additional information, it suffers from bleaching by ambient light and requires light-protection. Grain disinfestated with low irradiation doses (500 Gy) may not identified by both TL and PSL measurement. The natural TL of feldspar particles may be overlap with the irradiation-induced TL of other minerals. As a routine method, irradiated spices are identified with TL measurement. The dust particles have to be enriched by heavy-liquid flotation and centrifugation. The PSL method allows a clear

Changes of fluorescent spectral features after successive rare earth doping of gadolinium oxide powders

Energy Technology Data Exchange (ETDEWEB)

Kuznik, W. [Chemical Department, Silesian University of Technology, Gliwice (Poland); Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Brik, M.G. [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Cieslik, I.; Majchrowski, A.; Jaroszewicz, L. [Institute of Applied Physics, Military University of Technology, Kaliskiego 2, 00-908 Warsaw (Poland); AlZayed, N.S. [Physics and Astronomy Dept., College of Science, P.O. Box 2455, King Saud University, Riyadh 11451 (Saudi Arabia); El-Naggar, A.M. [Physics and Astronomy Dept., College of Science, P.O. Box 2455, King Saud University, Riyadh 11451 (Saudi Arabia); Permanent address: Physics department, Faculty of Science, Ain Shams University, Abassia, Cairo 11566 (Egypt); Sildos, I.; Lange, S.; Kiisk, V. [Institute of Physics, University of Tartu, Riia 142, Tartu 51014 (Estonia); Kityk, I.V., E-mail: ikityk@el.pcz.czest.pl [Electrical Engineering Department, Czestochowa University of Technology, Armii Krajowej 17, Czestochowa (Poland); Physics and Astronomy Dept., College of Science, P.O. Box 2455, King Saud University, Riyadh 11451 (Saudi Arabia)

2012-01-15

Highlights: > Principally new phosphors based on rare earth moped Gd{sub 2}O{sub 3} are obtained. > The time-resolved fluorescent spectra show drastic changes with the doping. > Temperature measurements were done. - Abstract: We present a complex fluorescence study of a series of gadolinium oxide polycrystalline powders singly, doubly and triply doped with trivalent rare earth ions (Er{sup 3+}, Tb{sup 3+}, and Dy{sup 3+}), to explore a possibility of their use as materials for white light emitting diodes. The excitation and luminescence spectra along with the decay kinetics were measured in the temperature range from 6 to 300 K. The luminescence efficiency was studied within the visible spectral range, i.e. -400 nm to 750 nm under excitation by 355 nm third harmonic Nd:YAG laser pulses. Singly doped Er{sup 3+} sample gave stronger luminescence signals, but others showed significantly larger decay lifetimes. The successive rare earths doping leads to substantial changes of the spectral positions due to the up-conversion processes. In the singly (Er{sup 3+}) doped sample, following the time resolved spectrum and decay curves, there are two different types of emissions: at 660 nm and at shorter wavelengths (below 640 nm) the red emission's lifetime is ten times longer than at shorter wavelengths. The singly doped sample shows unclear temperature-dependence of luminescence with lifetime at 550 nm (the longest at 100 K, similarly at 6 K and 300 K) and achieved luminous efficacy 73.5 lm/W.

Asymptotic scalings of developing curved pipe flow

Science.gov (United States)

Ault, Jesse; Chen, Kevin; Stone, Howard

2015-11-01

Asymptotic velocity and pressure scalings are identified for the developing curved pipe flow problem in the limit of small pipe curvature and high Reynolds numbers. The continuity and Navier-Stokes equations in toroidal coordinates are linearized about Dean's analytical curved pipe flow solution (Dean 1927). Applying appropriate scaling arguments to the perturbation pressure and velocity components and taking the limits of small curvature and large Reynolds number yields a set of governing equations and boundary conditions for the perturbations, independent of any Reynolds number and pipe curvature dependence. Direct numerical simulations are used to confirm these scaling arguments. Fully developed straight pipe flow is simulated entering a curved pipe section for a range of Reynolds numbers and pipe-to-curvature radius ratios. The maximum values of the axial and secondary velocity perturbation components along with the maximum value of the pressure perturbation are plotted along the curved pipe section. The results collapse when the scaling arguments are applied. The numerically solved decay of the velocity perturbation is also used to determine the entrance/development lengths for the curved pipe flows, which are shown to scale linearly with the Reynolds number.

Quartz luminescence response to a mixed alpha-beta field: Investigations on Romanian loess

DEFF Research Database (Denmark)

Constantin, Daniela; Jain, Mayank; Murray, Andrew S.

2015-01-01

-OSL laboratory dose response curves do not reflect the growth of the OSL signal in nature. A main difference in coarse- and fine-grained quartz dating lies in the alpha irradiation history, but the effect of mixed alpha-beta fields has so far received little attention. In the present study we investigate whether...... the alpha dose experienced by fine grains over geological cycles of irradiation and bleaching may have an effect on the saturation characteristics of the laboratory dose response. By applying time resolved optically stimulated luminescence we confirm that the OSL signals induced in quartz by alpha and beta...

Mobile interstitial model and mobile electron model of mechano-induced luminescence in coloured alkali halide crystals

International Nuclear Information System (INIS)

Chandra, B.P.; Singh, Seema; Ojha, Bharti; Shrivastava, R.G.

1996-01-01

A theoretical study is made on the mobile interstitial and mobile electron models of mechano-induced luminescence in coloured alkali halide crystals. Equations derived indicate that the mechanoluminescence intensity should depend on several factors like strain rate, applied stress, temperature, density of F-centres and volume of crystal. The equations also involve the efficiency and decay time of mechanoluminescence. Results of mobile interstitial and mobile electron models are compared with the experimental observations, which indicated that the latter is more suitable as compared to the former. From the temperature dependence of ML, the energy gaps between the dislocation band and ground state of F-centre is calculated which are 0.08, 0.072 and 0.09 eV for KCl, KBr and NaCl crystals, respectively. The theory predicts that the decay of ML intensity is related to the process of stress relaxation in crystals. (author). 33 refs., 5 figs., 1 tab

Cleavage Luminescence from Cleaved Indium Phosphide

International Nuclear Information System (INIS)

Dong-Guang, Li

2008-01-01

We outline the experiments performed to gain further information about the structure and properties of cleaved InP surfaces. The experiments involved detecting the luminescence produced after cleaving thin InP plates within a high vacuum, by a process of converting the luminescence to an electrical signal which could be amplified and measured accurately. The experimental results show that the detected luminescence durations from cleaved InP are usually only about 10μs. It is believed that this time represents the time of travel of the crack with the actual recombination time being much shorter. Strong signals could also be picked up from cleaved InP in air

Luminescent converter of neodymium laser radiation

International Nuclear Information System (INIS)

Ryba-Romanowski, W.; Golab, S.

1992-01-01

The new luminescent converter of neodymium laser radiation has been worked out. Activated inorganic compounds of ytterbium and erbium ions has been used as luminescent agent. The multi-component inorganic glass containing tellurium oxide as well as boron, sodium, magnesium and zinc oxides has been applied as a converter matrix

Thermoluminescent dosimetry and of optically stimulated luminescence of diamond films grown up by the chemical vapor deposition technique exposed to beta radiation

International Nuclear Information System (INIS)

Melendrez A, R.; Barboza F, M.

2002-01-01

A study of the dosimetric properties through the thermoluminescence (Tl) and Optically stimulated luminescence (Lobe) in diamond films grown up by the chemical vapor deposition (Dq) techniques was realized.The films under study have thickness of 6, 12, 180 and 500 microns. The dose range was from 0 to 1.5 KGy, observing for the case of the thermoluminescent dosimetry a linear behavior in the range 0-300 Gy and a supra linearity effect in the range from 300-1500 Gy. For the case of the dosimetry by means of LOE a linear behavior in the range (0-300 Gy) without be enough for the saturation was observed, although some samples exhibit a linear behavior until 1500 Gy (6 microns). The irradiation was realized with a source of Strontium 90 of (40 mCi) and the photoestimulation for realizing the measures of LOE was realized using diodes emitting of laser light (470 nm) which generate until 50 MW/cm 2 . The Tl peak which was used to realize the dosimetry such Tl as LOE was that located around 340 C degrees in the brilliance curve which presents another peaks centered around of 110, 190, and 340 C degrees, depending on the film. It was realized a study of the Tl signal drop and it was observed that after 3 hours the signal was stable reaching a decay of 15 %. the analysis of the drop in the Tl signal, immediately after to irradiate and after to photoestimulate with the blue light laser for observing the LOE, indicated that exists a fall in all the Tl peaks, decaying in greater proportion those of more low temperature. (Author)

Leptogenesis and gravity: Baryon asymmetry without decays

Directory of Open Access Journals (Sweden)

J.I. McDonald

2017-03-01

Full Text Available A popular class of theories attributes the matter-antimatter asymmetry of the Universe to CP-violating decays of super-heavy BSM particles in the Early Universe. Recently, we discovered a new source of leptogenesis in these models, namely that the same Yukawa phases which provide the CP violation for decays, combined with curved-spacetime loop effects, lead to an entirely new gravitational mechanism for generating an asymmetry, driven by the expansion of the Universe and independent of the departure of the heavy particles from equilibrium. In this Letter, we build on previous work by analysing the full Boltzmann equation, exploring the full parameter space of the theory and studying the time-evolution of the asymmetry. Remarkably, we find regions of parameter space where decays play no part at all, and where the baryon asymmetry of the Universe is determined solely by gravitational effects.

Luminescence spectroscopy with synchrotron radiation: History, highlights, future

International Nuclear Information System (INIS)

Zimmerer, Georg

2006-01-01

Luminescence spectroscopy and the investigation of dynamical processes with synchrotron radiation (SR) started about 35 years ago in nearly all SR laboratories existing at that time. In the present paper, the pioneering experiments are particularly emphasized. The exciting development is illustrated presenting highlights for the whole period from the beginning to the present day. The highlights are taken from fields like exciton self-trapping, inelastic electron-electron scattering, optically stimulated desorption, cross luminescence, or probing of cluster properties with luminescence spectroscopic methods. More technological aspects play a role in present day's experiments, like quantum cutting in rare-earth-doped insulators. Promising two-photon excitation and light amplification experiments with SR will be included, as well as the first results obtained in a luminescence experiment with selective Vaccum ultraviolet-free electron laser excitation. Finally, a few ideas concerning the future development of luminescence spectroscopy with SR will be sketched

Temperature dependence of fluorescence decay time and emission spectrum of bismuth germanate

International Nuclear Information System (INIS)

Melcher, C.L.; Liberman, A.; Schweitzer, J.S.; Simonetti, J.

1985-01-01

Bismuth germanate has become an increasingly popular replacement for NaI(Tl) scintillators in recent years, mainly due to its higher detection efficiency. However, its scintillation efficiency and fluorescence decay time are strongly temperature dependent. Optimum performance of detector systems which employ BGO crystals depends on knowledge of the BGO pulse shape and intensity and its emission spectrum at the operating temperature of the detector. Measurements of these quantities are presented over the temperature range -47 0 C to +111 0 C. Although the emission spectrum shifts only slightly over this temperature range, the scintillation efficiency and fluorescence decay time are strongly temperature dependent. In addition to the usefulness of these data for optimizing detector design, the results imply that luminescence quenching in BGO cannot be characterized by a single thermal activation to a radiationless transition but that a more complex model is required to characterize the light output from BGO crystals

Chemisorptive luminescence on γ-irradiated magnesium oxide

International Nuclear Information System (INIS)

Breakspere, R.J.; Read, R.L.

1976-01-01

The intensity of a chemisorptive luminescence produced on MgO by oxygen at room temperature is increased by prior γ-irradiation of the MgO, under vacuum, before adsorption. This enhancement of the luminescence increases with radiation dose up to 1.9 x 10 6 rad and is attributed to the interaction between the F + sub (s) centres produced by the radiation and oxygen molecules arriving at the surface from the gas phase. In this work, the spectrum of the emitted luminescence could not be measured. (author)

New systematics of cluster- and alpha-decay half lives

International Nuclear Information System (INIS)

Poenaru, D.N.; Greiner, W.

1994-01-01

Available as short communication only. The cluster (or 'exotic') radioactivities belong to a rich variety of nuclear decay modes which are phenomena intermediate between fission and alpha decay. In this contribution a single universal curve for the logarithm of the partial half-life for each kind of cluster radioactivity of even-even parent nuclei is presented. This handy relationship reproduces well the up to now 14 even-even half-life measurements within a ratio of 3.86 or rms=0.587 orders of magnitude. Its universality consists in the fact that instead of having different lines for various parent nuclei, like in the 'classical' systematics (Geiger-Nuttall plot) one can get practically only one line for each decay mode. (Author) 1 Fig., 2 Refs

LM-OSL signals from some insulators: an analysis of the dependency of the detrapping probability on stimulation light intensity

DEFF Research Database (Denmark)

Bulur, E.; Bøtter-Jensen, L.; Murray, A.S.

2001-01-01

Optically stimulated luminescence (OSL) signals from various insulators including quartz, Al2O3 : C, BeO and NaCl have been studied using the linear modulation OSL (LM-OSL) technique. LM-OSL is based on the linear increase of the stimulation light power from zero to a maximum during the measurement...... is not always correct. The initial decay rates of the blue (similar to 470 nm) light stimulated constant power OSL decay curves were examined to test the relation between the detrapping rates and the stimulation light intensity. In SiO2, Al2O3 : C and BeO a linear relation between the detrapping rates....... The resultant OSL curve initially increases and then decays after reaching a maximum, The analysis of LM-OSL data usually assumes a linear relationship between the detrapping rate and the stimulation light intensity. However, experiments carried out using various insulators have shown that this assumption...

Recombination dynamics and internal quantum efficiency in InGaN

International Nuclear Information System (INIS)

Murotani, Hideaki; Andoh, Hiroya; Tsukamoto, Takehiko; Sugiura, Toko; Yamada, Yoichi; Tabata, Takuya; Honda, Yoshio; Yamaguchi, Masahito; Amano, Hiroshi

2014-01-01

Recombination dynamics and internal quantum efficiency (IQE) of green luminescent InGaN nanowires with different crystalline qualities have been studied by means photoluminescence (PL) and time-resolved PL spectroscopy. Temperature- and excitation-power-density-dependent PL spectroscopy enabled to evaluate the IQE as a function of excitation power density. The shape of the efficiency curves at low temperature strongly depended on the magnitude of nonradiative recombination processes. This leads to the misestimation of the IQE in the lower quality nanowire. In addition, the PL decay curves were well described by a double exponential function both at 6 and 300 K. The PL decay time of the faster component was affected by nonradiative recombination processes even at low temperature. This indicated that the radiative recombination lifetime cannot be estimated from the PL decay time in the lower quality nanowire. (copyright 2014 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

Europium enabled luminescent nanoparticles for biomedical applications

Energy Technology Data Exchange (ETDEWEB)

Syamchand, S.S., E-mail: syamchand.ss@gmail.com; Sony, G., E-mail: emailtosony@gmail.com

2015-09-15

Lanthanide based nanoparticles are receiving great attention ought to their excellent luminescent and magnetic properties and find challenging biomedical applications. Among the luminescent lanthanide NPs, europium based NPs (Eu-NPs) are better candidates for immunoassay and imaging applications. The Eu-NPs have an edge over quantum dots (QDs) by means of their stable luminescence, long fluorescence lifetime, sharp emission peaks with narrow band width, lack of blinking and biocompatibility. This review surveys the synthesis and properties of a variety of Eu-NPs consolidated from different research articles, for their applications in medicine and biology. The exquisite luminescent properties of Eu-NPs are explored for developing biomedical applications such as immunoassay and bioimaging including multimodal imaging. The biomedical applications of Eu-NPs are mostly diagnostic in nature and mainly focus on various key analytes present in biological systems. The luminescent properties of europium enabled NPs are influenced by a number of factors such as the site symmetry, the metal nanoparticles, metal ions, quantum dots, surfactants, morphology of Eu-NPs, crystal defect, phenomena like antenna effect and physical parameters like temperature. Through this review we explore and assimilate all the factors which affect the luminescence in Eu-NPs and coil a new thread of parameters that control the luminescence in Eu-NPs, which would provide further insight in developing Eu-based nanoprobes for future biomedical prospects. - Highlights: • The review describes 14 major factors that influence the luminescence properties of europium enabled luminescent nanoparticles (Eu-NPs). • Surveys different types of europium containing nanoparticles that have been reported for their biomedical applications. • Eu-NPs are conveniently divided into four different categories, based on the type of the substrates involved. The four categories are (1) virgin Eu-substrate based NPs; (2

Europium enabled luminescent nanoparticles for biomedical applications

International Nuclear Information System (INIS)

Syamchand, S.S.; Sony, G.

2015-01-01

Lanthanide based nanoparticles are receiving great attention ought to their excellent luminescent and magnetic properties and find challenging biomedical applications. Among the luminescent lanthanide NPs, europium based NPs (Eu-NPs) are better candidates for immunoassay and imaging applications. The Eu-NPs have an edge over quantum dots (QDs) by means of their stable luminescence, long fluorescence lifetime, sharp emission peaks with narrow band width, lack of blinking and biocompatibility. This review surveys the synthesis and properties of a variety of Eu-NPs consolidated from different research articles, for their applications in medicine and biology. The exquisite luminescent properties of Eu-NPs are explored for developing biomedical applications such as immunoassay and bioimaging including multimodal imaging. The biomedical applications of Eu-NPs are mostly diagnostic in nature and mainly focus on various key analytes present in biological systems. The luminescent properties of europium enabled NPs are influenced by a number of factors such as the site symmetry, the metal nanoparticles, metal ions, quantum dots, surfactants, morphology of Eu-NPs, crystal defect, phenomena like antenna effect and physical parameters like temperature. Through this review we explore and assimilate all the factors which affect the luminescence in Eu-NPs and coil a new thread of parameters that control the luminescence in Eu-NPs, which would provide further insight in developing Eu-based nanoprobes for future biomedical prospects. - Highlights: • The review describes 14 major factors that influence the luminescence properties of europium enabled luminescent nanoparticles (Eu-NPs). • Surveys different types of europium containing nanoparticles that have been reported for their biomedical applications. • Eu-NPs are conveniently divided into four different categories, based on the type of the substrates involved. The four categories are (1) virgin Eu-substrate based NPs; (2

luminescence properties

Indian Academy of Sciences (India)

1Faculty of Science and Arts, Department of Chemistry, Bozok University, Yozgat 66900, Turkey. 2Faculty of Science, Department of Chemistry, Erciyes ... synthesized by the conventional solid-state reaction method, their crystal structures and luminescence properties were investigated. X-ray diffraction patterns (XRD) ...

Deposition of radon decay products on the skin of balneotherapy patients in Gastein

International Nuclear Information System (INIS)

Tempfer, H.; Schober, A.; Lettner, H.; Hofmann, W.; Foisner, W.; Steger, F.

2001-01-01

In Bad Gastein and Bad Hofgastein, radon-rich thermal water is used for the treatment of various diseases, especially for Morbus Bechterew, a degenerative illness of the spinal column. One of the therapeutic applications of the thermal water is the exposition of patients in 450 1 bathtubs (''Best'sche Wanne''). To check the hypothesis that the radon decay products contribute to the therapeutic effect, the adsorption behaviour of radon decay products was examined. A group of patients was exposed to the thermal water for 20 minutes. Immediately after leaving the bathtub, the activities were measured at several locations of the human body (forearms, belly, lower legs) by alpha spectrometry. The activities of the decay products 218 Po, 214 Pb and 214 Bi/ 214 Po were determined from the measured spectra and decay curves. In order to study the time dependence of the decay product adsorption, one test person was exposed for 10, 20, to 30, 40 and 60 minutes; afterwards the decay curves were recorded again over a period of 30 minutes. The results showed that the activities of the decay products on the skin can differ appreciably. On the one hand, the distribution on the body surface seems to be quite inhomogeneous, on the other hand, the deposition varies considerably from person to person. As a result of this, skin activities varied between 1.2 and 4.1 Bq/cm 2 . The exposition and measurement of copper and PVC plates confirmed earlier results, that the deposition of radon decay products in water on artificial surfaces is much less than that on living surfaces. In conclusion, the remarkably high decay product activities on the skin does indeed suggest a positive correlation with the observed therapeutic effects. (orig.) [de

Luminescent properties of fluorophosphate glasses with lead chalcogenides molecular clusters

International Nuclear Information System (INIS)

Kolobkova, E.V.; Kukushkin, D.S.; Nikonorov, N.V.; Shakhverdov, T.A.; Sidorov, A.I.; Vasiliev, V.N.

2015-01-01

Fluorophosphate glasses containing lead, selenium, and sulfur exhibit an intense luminescence in the 400–620 nm spectral region when excited by the 240–420 nm radiation. This luminescence is due to the presence of (PbSe) n and/or (PbS) n molecular clusters in the glasses, which appear in the as-prepared glasses before quantum dots formation. The thermal treatment at temperatures less than the glass transition temperature results in the red-shift of the luminescence bands and in an increase in the luminescence intensity. Heating the thermally treated glass samples leads to the reversible thermal quenching of the luminescence. - Highlights: • Fluorophosphate glasses with Pb, Se, and S ions contain (PbSe) n or (PbS) n molecular clusters. • (PbSe) n and (PbS) n molecular clusters possess luminescence in the visible with UV excitation. • Heating the glass leads to the reversible thermal quenching of the luminescence

Status of the Japanese decay heat standard

International Nuclear Information System (INIS)

Katakura, Jun-ichi

1992-01-01

Fission product decay heat power plays an important role in the safety evaluation of nuclear power plants, especially for the analysis of hypothetical reactor accident scenarios. The ANS-5.1 decay heat standard for safety evaluation issued in 1979 has been used widely, even in Japan. Since the issuance of the standard, several improvements have been made to measurements and summation calculations. Summation calculations, in particular, have improved because of the adoption of theoretically calculated decay energies for nuclides with incomplete decay data. Taking into consideration those improvements, the Atomic Energy Society of Japan (AESJ) organized a research committee on a standard for decay heat power in nuclear reactors in 1987. The committee issued its recommendation after more than 2 yr discussion. After the AESJ recommendation, the Nuclear Safety Commission of Japan also began to discuss whether the recommendation should be included in its regulatory guide. The commission concluded in 1992 that the recommendation should be approved for licensing analysis of reactors if three times the uncertainties attached to the recommendation are included in the analysis. The AESJ recommendation may now be used for the safety evaluation of reactors in Japan in addition to the standards already used, which include ANS-5.1 (1973), General Electric Corporation (GE) curve, and ANS-5.1 (1979)

Luminescent polymethyl methacrylate modified by gamma radiation

International Nuclear Information System (INIS)

Morais, Guilherme F.; Forster, Pedro L.; Marchini, Leonardo G.; Lugao, Ademar B.; Parra, Duclerc F.

2011-01-01

Thin films of PMMA (polymethyl methacrylate) doped with luminescent complexes have been studied and developed for applications in advanced technologies. The problem of stability of these films is focused in this study. Films stabilization by reaction with fluorinated monomers is a recent study that aims to increase its luminescence properties for long time. The films were prepared by dilution of PMMA in chloroform with addition of europium complex, at proportion of 5% by weight of polymer. The luminescent polymer films were obtained by casting. Thin layer slides of the film were separated in three parts. One was reacted with fluorinated monomers (C 2 F 4 ) in closed reactor for 48 hours. A second part was reacted with C 2 F 4 after irradiation in gamma source at 5 kGy in simultaneous process. The last part was used as obtained. The luminescent polymer matrices were characterized using the techniques of infrared (FTIR) and thermogravimetry (TGA/DTG). Samples of the films were, in presence of fluorine monomers, exposed to ionizing radiation in dose of 5 kGy, for react with monomers in the doped polymer surface. In this case the effects of radiation were evaluated on the luminescent films. (author)

Zero-reabsorption doped-nanocrystal luminescent solar concentrators.

Science.gov (United States)

Erickson, Christian S; Bradshaw, Liam R; McDowall, Stephen; Gilbertson, John D; Gamelin, Daniel R; Patrick, David L

2014-04-22

Optical concentration can lower the cost of solar energy conversion by reducing photovoltaic cell area and increasing photovoltaic efficiency. Luminescent solar concentrators offer an attractive approach to combined spectral and spatial concentration of both specular and diffuse light without tracking, but they have been plagued by luminophore self-absorption losses when employed on practical size scales. Here, we introduce doped semiconductor nanocrystals as a new class of phosphors for use in luminescent solar concentrators. In proof-of-concept experiments, visibly transparent, ultraviolet-selective luminescent solar concentrators have been prepared using colloidal Mn(2+)-doped ZnSe nanocrystals that show no luminescence reabsorption. Optical quantum efficiencies of 37% are measured, yielding a maximum projected energy concentration of ∼6× and flux gain for a-Si photovoltaics of 15.6 in the large-area limit, for the first time bounded not by luminophore self-absorption but by the transparency of the waveguide itself. Future directions in the use of colloidal doped nanocrystals as robust, processable spectrum-shifting phosphors for luminescent solar concentration on the large scales required for practical application of this technology are discussed.

Synchrotron radiation studies on luminescence of Eu2+-doped LaCl3 microcrystals embedded in a NaCl matrix

International Nuclear Information System (INIS)

Savchyn, P.V.; Vistovskyy, V.V.; Pushak, A.S.; Voloshinovskii, A.S.; Gektin, A.V.; Pankratov, V.; Popov, A.I.

2012-01-01

LaCl 3 :Eu 2+ microcrystals dispersed in the NaCl matrix have been obtained in the NaCl–LaCl 3 (1 mol.%)–EuCl 3 (0.1 mol.%) crystalline system. The low-temperature luminescent properties of these microcrystals have been studied upon the VUV and UV excitation by the synchrotron radiation. The spectroscopic parameters as well as decay time constants of Eu 2+ -doped LaCl 3 host have been established. The excitation mechanism of divalent europium centers through energy transfer and reabsorption is discussed.

Intrinsic luminescence of un-doped borate glasses

International Nuclear Information System (INIS)

Kindrat, I.I.; Padlyak, B.V.; Drzewiecki, A.

2017-01-01

The nature of intrinsic luminescence in the un-doped borate glasses of different compositions has been investigated using spectroscopic methods including photoluminescence, optical absorption, electron paramagnetic resonance (EPR), and thermally stimulated luminescence (TSL). The un-doped borate glasses with Li 2 B 4 O 7 , LiKB 4 O 7 , CaB 4 O 7 , and LiCaBO 3 basic compositions were obtained from corresponding polycrystalline compounds in the air with usage the standard technology of glasses. Three different broad emission bands in the UV–Visible spectral range have been observed under different wavelength of photoexcitation. The luminescence kinetics of the observed emission bands have been registered and analysed. The nature and possible mechanisms of the intrinsic luminescence in the investigated borate glasses are considered and discussed based on the obtained results and referenced data.

Oxide/polymer nanocomposites as new luminescent materials

Science.gov (United States)

Vollath, D.; Szabó, D. V.; Schlabach, S.

2004-06-01

It is demonstrated that nanocomposites, consisting of an electrically insulating oxide core and PMMA coating exhibit strong luminescence. This luminescence is connected to the interface, where PMMA is bond via a carboxylate bonding to the surface. In this case, luminescence is originated at the carbonyl group of the coating polymer. With decreasing particle size, this emission shows a blue shift, following a law inversely the ones found for quantum confinement systems. For semi-conducting oxides, such as ZnO, this interface related emission is found additionally to quantum confinement phenomena.

A comparative study of the models dealing with localized and semi-localized transitions in thermally stimulated luminescence

International Nuclear Information System (INIS)

Kumar, Munish; Kher, R K; Bhatt, B C; Sunta, C M

2007-01-01

Different models dealing with localized and semi-localized transitions, namely Chen-Halperin, Mandowski and the model based on the Braunlich-Scharmann (BS) approach are compared. It has been found that for recombination dominant situations (r > 1, the three models differ. This implies that for localized transitions under recombination dominant situations, the Chen-Halperin model is the best representative of the thermally stimulated luminescence (TSL) process. It has also been found that for the TSL glow curves arising from delocalized recombination in Mandowski's semi-localized transitions model, the double peak structure of the TSL glow curve is a function of the radiation dose as well as of the heating rate. Further, the double peak structure of the TSL glow curves arising from delocalized recombination disappears at low doses as well as at higher heating rates. It has also been found that the TSL glow curves arising from delocalized recombination in the semi-localized transitions model based on the BS approach do not exhibit double peak structure as observed in the Mandowski semi-localized transitions model

Application of luminescence techniques in retrospective dosimetry

DEFF Research Database (Denmark)

Bøtter-Jensen, L.; Jungner, H.

1999-01-01

Luminescence signals measured from minerals within bricks or ceramic samples can provide information about the absorbed radiation dose. This feature has for several years been used in dating archaeological and geological samples and recently luminescence techniques have been intensively used far ...

Luminescence at the end of the tunnelling - Investigating charge transfer mechanisms and luminescence dating methods for feldspar minerals

NARCIS (Netherlands)

Kars, R.H.

2014-01-01

This thesis comprises analyses of mineral physics with an application in geology and archeology. The thesis contributes to the development of feldspar luminescence dating methods in order to extend the applicable age range of feldspar luminescence dating in the Quaternary (last 2.6 Ma). The research

Luminescence and the light emitting diode the basics and technology of leds and the luminescence properties of the materials

CERN Document Server

Williams, E W; Pamplin, BR

2013-01-01

Luminescence and the Light Emitting Diode: The Basics and Technology of LEDS and the Luminescence Properties of the Materials focuses on the basic physics and technology of light emitting diodes (LEDS) and pn junction lasers as well as their luminescence properties. Optical processes in semiconductors and the useful devices which can be made are discussed. Comprised of 10 chapters, this book begins with an introduction to the crystal structure and growth, as well as the optical and electrical properties of LED materials. The detailed fabrication of the LED is then considered, along with the lu

A facile synthesis approach and impact of shell formation on morphological structure and luminescent properties of aqueous dispersible NaGdF{sub 4}:Yb/Er upconversion nanorods

Energy Technology Data Exchange (ETDEWEB)

Ansari, Anees A., E-mail: aneesaansari@gmail.com [King Saud University, King Abdullah Institute for Nanotechnology (Saudi Arabia); Yadav, Ranvijay; Rai, S. B. [Banaras Hindu University, Department of Physics (India)

2016-12-15

A general facile synthesis approach was used for fabrication of highly emissive aqueous dispersible hexagonal phase upconversion luminescent NaGdF{sub 4}:Yb/Er nanorods (core NRs) through metal complex decomposition process. An inert NaGdF{sub 4} and porous silica layers were grafted surrounding the surface of each and every NRs to enhance their luminescence efficiency and colloidal dispersibility in aqueous environment. Optical properties in terms of band gap energy of core, core/shell, and silica-coated core/shell/SiO{sub 2} nanorods were observed to investigate the influence of surface coating, which was gradually decreased after surface coating because of increase crystalline size after growth of inert and silica shells. The inert shell formation before silica surface grafting, upconversion luminescence intensity was greatly improved by about 20 times, owing to the effective surface passivation of the seed core and, therefore, protection of Er{sup 3+} ion in the core from the nonradiative decay caused by surface defects. Moreover, after silica coating, core/shell nanorods shows strong upconversion luminescence property similar to the hexagonal upconversion core NRs. It is expected that these NaGdF{sub 4}:Yb/Er@NaGdF{sub 4}@SiO{sub 2} (core/shell/SiO{sub 2}) NRs including highly upconversion emissive and aqueous dispersible properties make them an ideal materials for various photonic-based potential applications such as in upconversion luminescent bioimaging, magnetic resonance imaging, and photodynamic therapy.

Ratiometric Time-Gated Luminescence Probe for Nitric Oxide Based on an Apoferritin-Assembled Lanthanide Complex-Rhodamine Luminescence Resonance Energy Transfer System.

Science.gov (United States)

Tian, Lu; Dai, Zhichao; Liu, Xiangli; Song, Bo; Ye, Zhiqiang; Yuan, Jingli

2015-11-03

Using apoferritin (AFt) as a carrier, a novel ratiometric luminescence probe based on luminescence resonance energy transfer (LRET) between a Tb(3+) complex (PTTA-Tb(3+)) and a rhodamine derivative (Rh-NO), PTTA-Tb(3+)@AFt-Rh-NO, has been designed and prepared for the specific recognition and time-gated luminescence detection of nitric oxide (NO) in living samples. In this LRET probe, PTTA-Tb(3+) encapsulated in the core of AFt is the energy donor, and Rh-NO, a NO-responsive rhodamine derivative, bound on the surface of AFt is the energy acceptor. The probe only emits strong Tb(3+) luminescence because the emission of rhodamine is switched off in the absence of NO. Upon reaction with NO, accompanied by the turn-on of rhodamine emission, the LRET from Tb(3+) complex to rhodamine occurs, which results in the remarkable increase and decrease of the long-lived emissions of rhodamine and PTTA-Tb(3+), respectively. After the reaction, the intensity ratio of rhodamine emission to Tb(3+) emission, I565/I539, is ∼24.5-fold increased, and the dose-dependent enhancement of I565/I539 shows a good linearity in a wide concentration range of NO. This unique luminescence response allowed PTTA-Tb(3+)@AFt-Rh-NO to be conveniently used as a ratiometric probe for the time-gated luminescence detection of NO with I565/I539 as a signal. Taking advantages of high specificity and sensitivity of the probe as well as its good water-solubility, biocompatibility, and cell membrane permeability, PTTA-Tb(3+)@AFt-Rh-NO was successfully used for the luminescent imaging of NO in living cells and Daphnia magna. The results demonstrated the efficacy of the probe and highlighted it's advantages for the ratiometric time-gated luminescence bioimaging application.

Novel Mechano-Luminescent Sensors Based on Piezoelectric/Electroluminescent Composites

Directory of Open Access Journals (Sweden)

Yunzhang Fang

2011-04-01

Full Text Available A high-sensitivity mechano-luminescent sensor was fabricated on the basis of piezoelectric/electroluminescent composites. The working principle of this mechano-luminescent sensor was elucidated by analyzing the relationship between the piezoelectric-induced charges and the electroluminescent effects. When a stress is applied on the piezoelectric layer, electrical charges will be induced at both the top and bottom sides of the piezoelectric layer. The induced electrical charges will lead to a light output from the electroluminescent layer, thus producing a mechano-luminescence effect. By increasing the vibration strength or frequency applied, the mechano-luminescence output can be obviously enhanced. Mechano-luminescence sensors have potential in smart stress-to-light devices, such as foot-stress-distribution-diagnosis systems and dynamic-load-monitors for bridge hanging cables.

The crystal structure and luminescence quenching of poly- and single-crystalline KYW{sub 2}O{sub 8}:Tb{sup 3+}

Energy Technology Data Exchange (ETDEWEB)

Schwung, Sebastian [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Rytz, Daniel, E-mail: rytz@fee-io.de [Forschungsinstitut für mineralische und metallische Werkstoffe-Edelsteine/ Edelmetalle-GmbH (FEE), Struthstraße 2, 55743 Idar-Oberstein (Germany); Heying, Birgit; Rodewald, Ute Ch.; Niehaus, Oliver [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30 48149 Münster (Germany); Enseling, David [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Jüstel, Thomas, E-mail: tj@fh-muenster.de [Fachbereich Chemieingenieurwesen, Fachhochschule Münster, Stegerwaldstraße 39, 48565 Steinfurt (Germany); Pöttgen, Rainer, E-mail: pottgen@uni-muenster.de [Institut für Anorganische und Analytische Chemie, Universität Münster, Corrensstrasse 30 48149 Münster (Germany)

2015-10-15

Terbium-substituted KYW{sub 2}O{sub 8} single crystals of high optical quality were grown by the top seeded solution growth technique. The degree of yttrium–terbium mixed occupancy was determined for two samples through structure refinements on the basis of single crystal X-ray diffractometer data. Temperature dependent magnetic susceptibility data underline the paramagnetic nature of terbium doped crystals. No magnetic ordering is evident down to 2 K. Luminescence measurements yield the typical excitation and emission spectra as expected for Tb{sup 3+} activated materials. The decay time of Tb{sup 3+} decreases linearly with the Tb{sup 3+} concentration, while the excess of thermal quenching does not change significantly. At about 405 K the decay time is reduced by roughly 50% relative to the low-temperature value, both for the powders as for the single crystals. - Highlights: • Single crystalline and powder series of K(Y,Tb)W{sub 2}O{sub 8.} • Refined XRD data of high quality crystals. • Linear decrease of the decay time with Tb{sup 3+} content.

Photoinduced proton transfer coupled with energy transfer: Mechanism of sensitized luminescence of terbium ion by salicylic acid doped in polymer.

Science.gov (United States)

Misra, Vinita; Mishra, Hirdyesh

2008-06-28

In the present work, excited state intramolecular proton transfer (ESIPT) in salicylic acid (SA) monoanion and subsequent sensitization of Tb(3+) ion in polyvinyl alcohol (PVA) have been studied. The study has been carried out both by steady state and time domain fluorescence measurement techniques at room temperature. It is found that the SA completely ionizes and exists as monoanion in PVA. It exhibits a large Stokes shifted blue emission (10 000 cm(-1)) due to ESIPT and shows a decay time of 6.85 ns. On the other hand, Tb(3+) ion shows a very weak green emission and a decay time of approximately 641 mus in PVA film. Upon incorporating Tb(3+) ion in SA doped PVA film, both intensity and decay time of SA decrease and sensitized emission from Tb(+3) ion along with 3.8 mus rise time is observed. Energy transfer is found to take place both from excited singlet as well as triplet states. A brief description of the properties of the present system from the viewpoint of luminescent solar collector material is addressed.

Increasing lanthanide luminescence by use of the RETEL effect.

Science.gov (United States)

Leif, Robert C; Vallarino, Lidia M; Becker, Margie C; Yang, Sean

2006-08-01

Luminescent lanthanide complexes produce emissions with the narrowest-known width at half maximum; however, their significant use in cytometry required an increase in luminescence intensity. The companion review, Leif et al., Cytometry 2006;69A:767-778, described a new technique for the enhancement of lanthanide luminescence, the Resonance Energy Transfer Enhanced Luminescence (RETEL) effect, which increases luminescence and is compatible with standard slide microscopy. The luminescence of the europium ion macrocyclic complex, EuMac, was increased by employing the RETEL effect. After adding the nonluminescent gadolinium ion complex of the thenoyltrifluoroacetonate (TTFA) ligand or the sodium salt of TTFA in ethanol solution, the EuMac-labeled sample was allowed to dry. Both a conventional arc lamp and a time-gated UV LED served as light sources for microscopic imaging. The emission intensity was measured with a CCD camera. Multiple time-gated images were summed with special software to permit analysis and effective presentation of the final image. With the RETEL effect, the luminescence of the EuMac-streptavidin conjugate increased at least six-fold upon drying. Nuclei of apoptotic cells were stained with DAPI and tailed with 5BrdUrd to which a EuMac-anti-5BrdU conjugate was subsequently attached. Time-gated images showed the long-lived EuMac luminescence but did not show the short-lived DAPI fluorescence. Imaging of DNA-synthesizing cells with an arc lamp showed that both S phase and apoptotic cells were labeled, and that their labeling patterns were different. The images of the luminescent EuMac and fluorescent DAPI were combined to produce a color image on a white background. This combination of simple chemistry, instrumentation, and presentation should make possible the inexpensive use of the lanthanide macrocycles, Quantum Dyes, as molecular diagnostics for cytological and histopathological microscopic imaging. (c) 2006 International Society for Analytical

Luminescent solar concentrator

Directory of Open Access Journals (Sweden)

Tugce Tosun

2015-07-01

Full Text Available Luminescent solar concentrator (LSC is a device that has luminescent molecules embedding or topping polymeric or glass waveguide to generate electricity from sunlight with a photovoltaic cell attachment. LSCs can be employed both in small and large scale projects, independent on the direction or angle of the surface with respect to the sun, promising more freedom for integration in urban environments compared to the traditional PV systems. The aim of the SEB&C PDEng project is to investigate the applicability of this innovative technology in the built environment and to bridge the gap of knowledge linking societal, design and technological aspects. The final goal is to exhibit potential application concepts of LSC developed by co-creative methods at SPARK campus which is a hub for open innovation in built environment. Necessity of a paradigm shift towards sustainable and smart cities came into being due to the significant increase in energy demand of the buildings. The challenge is to increase renewable sources in the energy mix while designing aesthetic environments. Thus, building integrated renewable energy technologies represent a great opportunity to help overcome this current challenge. Smart energy, energy efficiency and use of renewable sources are key aspects to be considered nowadays and many innovative technologies need further exploitation to be commercially viable, such as luminescent solar concentrator.

Statistical analysis of time-resolved emission from ensembles of semiconductor quantum dots: interpretations of exponantial decay models

NARCIS (Netherlands)

van Driel, A.F.; Nikolaev, I.; Vergeer, P.; Lodahl, P.; Vanmaekelbergh, D.; Vos, Willem L.

2007-01-01

We present a statistical analysis of time-resolved spontaneous emission decay curves from ensembles of emitters, such as semiconductor quantum dots, with the aim of interpreting ubiquitous non-single-exponential decay. Contrary to what is widely assumed, the density of excited emitters and the

Polymethylmethacrylate-based luminescent solar concentrators with bottom-mounted solar cells

International Nuclear Information System (INIS)

Zhang, Yi; Sun, Song; Kang, Rui; Zhang, Jun; Zhang, Ningning; Yan, Wenhao; Xie, Wei; Ding, Jianjun; Bao, Jun; Gao, Chen

2015-01-01

Graphical abstract: - Highlights: • Bottom-mounted luminescent solar concentrators on dye-doped plates were studied. • The mechanism of transport process was proposed. • The fabricated luminescent solar concentrator achieved a gain of 1.38. • Power conversion efficiency of 5.03% was obtained with cell area coverage of 27%. • The lowest cost per watt of $1.89 was optimized with cell area coverage of 18%. - Abstract: Luminescent solar concentrators offer an attractive approach to concentrate sunlight economically without tracking, but the narrow absorption band of luminescent materials hinders their further development. This paper describes bottom-mounted luminescent solar concentrators on dye-doped polymethylmethacrylate plates that absorb not only the waveguided light but also the transmitted sunlight and partial fluorescent light in the escape cone. A series of bottom-mounted luminescent solar concentrators with size of 78 mm × 78 mm × 7 mm were fabricated and their gain and power conversion efficiency were investigated. The transport process of the waveguided light and the relationship between the bottom-mounted cells were studied to optimize the performance of the device. The bottom-mounted luminescent solar concentrator with cell area coverage of 9% displayed a cell gain of 1.38, to our best knowledge, which is the highest value for dye-doped polymethylmethacrylate plate luminescent solar concentrators. Power conversion efficiency as high as 5.03% was obtained with cell area coverage of 27%. Furthermore, the bottom-mounted luminescent solar concentrator was found to have a lowest cost per watt of $1.89 with cell area coverage of 18%. These results suggested that the fabricated bottom-mounted luminescent solar concentrator may have a potential in low-cost building integrated photovoltaic application

Luminescence properties and dynamical processes of energy transfer in BiPO{sub 4}: Tb{sup 3+},Eu{sup 3+} phosphor

Energy Technology Data Exchange (ETDEWEB)

Zhong, Jianming; Zhao, Weiren, E-mail: zwren123@126.com; Song, Enhai; Deng, Yongqiang

2014-10-15

A series of new emission-tunable phosphors Bi{sub 0.95−y}PO{sub 4}:0.05Tb{sup 3+},yEu{sup 3+} were synthesized by a facile hydrothermal method with surfactant-free environment. XRD results indicated that phosphors possess the standard BiPO{sub 4} monoclinic structure. From the luminescence spectra and decay curves, the energy transfer from Tb{sup 3+} to Eu{sup 3+} was confirmed. The efficient Tb{sup 3+} to Eu{sup 3+} energy transfer can be used to tune the emission color from green, yellow to orange by simply changing the concentration of europium, making the materials have potential applications in three-color-based displays and white light illumination. Finally, the energy transfer mechanism between Tb{sup 3+} and Eu{sup 3+} was demonstrated to be the electric quadrupole–quadrupole interaction based on Dexter's energy transfer formula and the Inokuti–Hirayama model. - Highlights: • BiPO{sub 4}: Tb{sup 3+}, Eu{sup 3+} phosphor was synthesized by a facile hydrothermal method. • Energy transfer from Tb{sup 3+} to Eu{sup 3+} in BiPO{sub 4} was firstly studied. • The Q–Q interaction is the main mechanism for energy transfer from Tb{sup 3+} to Eu{sup 3+}. • BiPO{sub 4}: Tb{sup 3+}, Eu{sup 3+} has potential applications in white LEDs and display devices.

Contrast and decay of cathodoluminescence from phosphor particles in a scanning electron microscope

Energy Technology Data Exchange (ETDEWEB)

Engelsen, Daniel den; Harris, Paul G.; Ireland, Terry G., E-mail: terry.ireland@brunel.ac.uk; Fern, George R.; Silver, Jack

2015-10-15

Cathodoluminescence (CL) studies are reported on phosphors in a field emission scanning electron microscope (FESEM). ZnO: Zn and other luminescent powders manifest a bright ring around the periphery of the particles: this ring enhances the contrast. Additionally, particles resting on top of others are substantially brighter than underlying ones. These phenomena are explained in terms of the combined effects of electrons backscattered out of the particles, together with light absorption by the substrate. The contrast is found to be a function of the particle size and the energy of the primary electrons. Some phosphor materials exhibit a pronounced comet-like structure at high scan rates in a CL-image, because the particle continues to emit light after the electron beam has moved to a position without phosphor material. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. The effect of phosphor saturation on the determination of decay times by CL-microscopy was also investigated. - Highlights: • Contrast enhancement are observed in secondary electron and cathodoluminescent images of phosphor particles sitting on top of others. • Backscattered electrons largely explain the observed contrast enhancement. • After glow effects in CL-micrographs of phosphors enable the determination of decay times. • Phosphor saturation can be used to determine the decay time of individual spectral transitions.

Photoluminescence, afterglow and thermoluminescence in SrAl2O4:Eu2+,Dy3+ irradiated with blue and UV light

International Nuclear Information System (INIS)

Chernov, V.; Piters, T.M.; Melendrez, R.; Yen, W.M.; Cruz-Zaragoza, E.; Barboza-Flores, M.

2007-01-01

The luminescence in SrAl 2 O 4 :Eu 2+ ,Dy 3+ under continuous excitation is quite different from the 'standard' intra-ion photoluminescence (PL) and gradually grows during hundreds of seconds before reaching the saturation (photo-charging effect). In this work, we report the behavior of photo-charging effect under the blue and UV light irradiation at temperatures between 20 and 370 K, as well as afterglow (AG) and thermoluminescence (TL) observed after the irradiation termination. At 20 K the photo-charging effect is absent. With increasing temperature the photo-charging effect appears as a result of PL decreasing due to competitive trapping process with activation energy of 0.17 eV. The AG decay curves are described well by the Becquerel's law with the exponent close to 1. The AG decay time is about 10-50 s and practically does not depend on temperature. The TL glow curve exhibits at least seven partially overlapped peaks with maxima at 50, 65, 80, 155, 200, 250 and 290 K. The emission spectra of Eu 2+ consist of two bands at 450 and 520 nm. Both the bands are the same for the PL, AG and TL spectra, but their ratio depends on temperature and the luminescence type

SIMULTANEOUS MEASUREMENT OF FREE RADICAL DECAY IN POLYMERIZATION OF MMA INITIATED BY AIBN USING ESR AND ITS KINETIC MODEL

Institute of Scientific and Technical Information of China (English)

Ping Xia; Qing-song Hu; Xiao-lan Qian; Xul-in Jiang; De-yue Yan

2001-01-01

The kinetics of free radical decay in the polymerization of MMA initiated by AIBN was studied by means of ESR spectroscopy. It was found that the curves of radical decay are strongly associated with the reaction temperature, the initiator concentration and the solvent. In the case of the radical polymerization carried out at high temperature or in solution, the radical concentration first reached a maximum, then declined monotonously with reaction time. It was also found that the greater the amount of initiator or the higher the temperature, the more rapidly the radicals decay. When the bulk polymerization was implemented at a relatively low temperature, the curves of radical decay became more complicated, i.e.,the radical concentration rapidly rose to a maximum, then dropped to a minimum, finally increased again with reaction time.Taking into account the diffusion effect, a semi-empirical equation is suggested to describe the kinetics of propagating radical decay.

Kinetics of infrared stimulated luminescence from feldspars

DEFF Research Database (Denmark)

Jain, Mayank; Sohbati, Reza; Guralnik, Benny

2015-01-01

thermal and optical, of the infrared stimulated luminescence signal from feldspar. Based on the application of this model, it is concluded that different infra-red stimulated luminescence emissions (UV, blue, yellow and far-red) follow the same kinetics, and, therefore, involve participation of the same...

EC/β+ decay of 161Er

International Nuclear Information System (INIS)

Kalinnikov, V.G.; Ibraheem, Y.S.; Stegailov, V.I.

2004-01-01

Full text: The study of odd-proton nuclei in rare-earth region has been performed to get more information on the nuclear structure of these nuclei. In the framework of a program at the ISOL complex of YASNAPP-2 at JINR to study the decay of odd-nuclei, 161 Er has been investigated. The experiments have been focused on the 161 Ho level scheme populated in the EC/β + decay of 161 Er for which a few results have been previously reported [1,2]. Spectra of single γ-ray, γ-γ coincidence and internal conversion electrons were measured. There are appreciable disagreements between results of some γ-ray intensities obtained by us and in [2]. The greatest difference was for relative γ-ray intensity of the 11.28 keV, which has reported value I γ ∼ 10 (I γ 211 =1000) in [2], but this leads to an overpopulation of the 211 keV level by 14% of the decay [3]. The relative intensities of transitions with Eγ γ211 =1000). Inaccuracy of Iγ in [2] is probably due to a sudden change in the efficiency curve of their Ge(Li) detector in the low energy region while our HPGe detector feature a much smoother variation in the efficiency curve in this γ-ray energy region. Besides, the levels earlier introduced by us in [4], three new levels in 161 Ho were proposed from γ-γ coincidences at energies 693.2 keV, 859.6 keV, and 957.97 keV. Spins, parities and Nilsson quantum characteristics of some 161 Ho levels were established

Process for obtaining luminescent glass layers

International Nuclear Information System (INIS)

Heindi, R.; Robert, A.

1984-01-01

Process for obtaining luminescent glass layers, application to the production of devices provided with said layers and to the construction of photoscintillators. The process comprises projecting onto a support, by cathodic sputtering, the material of at least one target, each target including silica and at least one chemical compound able to give luminescent centers, such as a cerium oxide, so as to form at least one luminescent glass layer of the said support. The layer or layers formed preferably undergo a heat treatment such as annealing in order to increase the luminous efficiency thereof. It is in this way possible to form a scintillating glass layer on the previously frosted entrance window of a photomultiplier in order to obtain an integrated photoscintillator

Luminescent polymethyl methacrylate modified by gamma radiation

Energy Technology Data Exchange (ETDEWEB)

Morais, Guilherme F. [Faculdade de Tecnologia de Sao Paulo (FATEC-ZL), Sao Paulo, SP (Brazil); Forster, Pedro L.; Marchini, Leonardo G.; Lugao, Ademar B.; Parra, Duclerc F., E-mail: dfparra@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

2011-07-01

Thin films of PMMA (polymethyl methacrylate) doped with luminescent complexes have been studied and developed for applications in advanced technologies. The problem of stability of these films is focused in this study. Films stabilization by reaction with fluorinated monomers is a recent study that aims to increase its luminescence properties for long time. The films were prepared by dilution of PMMA in chloroform with addition of europium complex, at proportion of 5% by weight of polymer. The luminescent polymer films were obtained by casting. Thin layer slides of the film were separated in three parts. One was reacted with fluorinated monomers (C{sub 2}F{sub 4}) in closed reactor for 48 hours. A second part was reacted with C{sub 2}F{sub 4} after irradiation in gamma source at 5 kGy in simultaneous process. The last part was used as obtained. The luminescent polymer matrices were characterized using the techniques of infrared (FTIR) and thermogravimetry (TGA/DTG). Samples of the films were, in presence of fluorine monomers, exposed to ionizing radiation in dose of 5 kGy, for react with monomers in the doped polymer surface. In this case the effects of radiation were evaluated on the luminescent films. (author)

A novel low cost pulse excitation source to study trap spectroscopy of persistent luminescent materials

Science.gov (United States)

Chandrasekhar, Ngangbam; Singh, Nungleppam Monorajan; Gartia, R. K.

2018-04-01

Luminescent techniques require one or the other source of excitations which may vary from high cost X-rays, γ-rays, β-rays etc. to low cost LED. Persistent luminescent materials or Glow-in-the-Dark phosphors are the optical harvesters which store the optical energy from day light illuminating a whole night. They are so sensitive that they can be excited even with the low light of firefly. Therefore, instead of using a high cost excitation source authors have developed a low cost functioning of excitation source controlling short pulses of LED to excite persistent phosphors with the aid of ExpEYES Junior (Hardware/software framework developed by IUAC, New Delhi). Using this, the authors have excited the sample under investigation upto 10 ms. Trap spectroscopy of the pre-excited sample with LED is studied using Thermoluminescence (TL) technique. In this communication, development of the excitation source is discussed and demonstrate the its usefulness in the study of trap spectroscopy of commercially available CaS:Eu2+, Sm3+. Trapping parameters are also evaluated using Computerized Glow Curve Deconvolution (CGCD) technique.

Photostimulated luminescence from a fluorobromozirconate glass-ceramic and the effect of crystallite size and phase

CERN Document Server

Secu, M; Spaeth, J M; Edgar, A; Williams, G V M; Rieser, U

2003-01-01

We report a systematic study of the photoluminescence (PL), photostimulated luminescence (PSL) and thermostimulated luminescence (TSL) from europium-and bromine-doped fluorozirconate glass-ceramics. Eu sup 2 sup + ions in the as-prepared glass show no PL, but after suitable thermal annealing hexagonal phase and orthorhombic phase barium bromide crystallites are precipitated and PL is observed from Eu sup 2 sup + ions in these crystallites. Room temperature PSL is observed from the orthorhombic phase, with an efficiency which is up to 9% of the well known crystalline storage phosphor BaFBr:Eu sup 2 sup +. The emission is at 404 nm, and there is a maximum in the stimulation at 580 nm. We associate the PSL with an optically quenchable peak in the glow curve, which has an activation energy of 1.20 eV and attribute this feature to a perturbed F centre. Room temperature PSL from glass-ceramics containing predominantly the hexagonal phase of BaBr sub 2 has a relative efficiency of less than 0.07%. The resultant trap...

On luminescence lifetimes in quartz

International Nuclear Information System (INIS)

Chithambo, M.L.; Galloway, R.B.

2000-01-01

In this paper we present results of investigations concerning the time dependence of luminescence emission relative to the time of stimulation in quartz. Measurements of time-resolved spectra were performed on a new versatile pulsed light emitting diode system using 525 nm stimulation, an 11 μs duration pulse, a repetition rate of 11 kHz and a 64 μs dynamic range. Effects on luminescence lifetime resulting from sample treatments such as optical stimulation, irradiation, and preheating, are reported

Origin of slow low-temperature luminescence in undoped and Ce-doped Y.sub.2./sub.SiO.sub.5./sub. and Lu.sub.2./sub.SiO.sub.5./sub. single crystals

Czech Academy of Sciences Publication Activity Database

Jarý, Vítězslav; Krasnikov, A.; Nikl, Martin; Zazubovich, S.

2015-01-01

Roč. 252, č. 2 (2015), s. 274-281 ISSN 0370-1972 R&D Projects: GA ČR GAP204/12/0805 Institutional support: RVO:68378271 Keywords : decay kinetics * luminescence * Lu 2 SiO 5 * time-resolved spectra * Y 2 SiO 5 Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.522, year: 2015

Fabrication of luminescent porous silicon with stain etches and evidence that luminescence originates in amorphous layers

Science.gov (United States)

Fathauer, R. W.; George, T.; Ksendzov, A.; Lin, T. L.; Pike, W. T.; Vasquez, R. P.; Wu, Z.-C.

1992-01-01

Simple immersion of Si in stain etches of HF:HNO3:H2O or NaNO2 in aqueous HF was used to produce films exhibiting luminescence in the visible similar to that of anodically-etched porous Si. All of the luminescent samples consist of amorphous porous Si in at least the near surface region. No evidence was found for small crystalline regions within these amorphous layers.

Photonic band edge assisted spontaneous emission enhancement from all Er3+ 1-D photonic band gap structure

Science.gov (United States)

Chiasera, A.; Meroni, C.; Varas, S.; Valligatla, S.; Scotognella, F.; Boucher, Y. G.; Lukowiak, A.; Zur, L.; Righini, G. C.; Ferrari, M.

2018-06-01

All Er3+ doped dielectric 1-D Photonic Band Gap Structure was fabricated by rf-sputtering technique. The structure was constituted by of twenty pairs of SiO2/TiO2 alternated layers doped with Er3+ ions. The scanning electron microscopy was used to check the morphology of the structure. Transmission measurements put in evidence the stop band in the range 1500 nm-1950 nm. The photoluminescence measurements were obtained by optically exciting the sample and detecting the emitted light in the 1.5 μm region at different detection angles. Luminescence spectra and luminescence decay curves put in evidence that the presence of the stop band modify the emission features of the Er3+ ions.

Enhanced green upconversion by controlled ceramization of Er3+–Yb3+ co-doped sodium niobium tellurite glass–ceramics for low temperature sensors

International Nuclear Information System (INIS)

Suresh Kumar, J.; Pavani, K.; Graça, M.P.F.; Soares, M.J.

2014-01-01

Highlights: • Upconversion luminescence improved in glass–ceramics compared to host glass. • Judd–Ofelt and radiative parameters calculated. • NIR decay curve results concur the results of improved luminescence. • Temperature dependent upconversion support the use of materials for sensors. - Abstract: Tellurite based glasses are well-known for their upconversion properties besides having a disadvantage of low mechanical strength dragging them away from practical applications. The present work deals with preparation of sodium niobium tellurite (SNT) glasses using melt quenching method, in which small quantities of boron and silicon in the form of oxides are added to improve their mechanical properties. Controlled heat treatment is performed to ceramize the prepared glasses based on the thermal data given by DTA. XRD and SEM profiles of the glass–ceramics which confirmed the formation of crystalline monoclinic Sodium Tellurium Niobium Oxide (Na 1.4 Nb 3 Te 4.9 O 18 ) phase (JCPDS card No. 04–011-7556). Upconversion measurements in the visible region were made for the prepared Er 3+ –Yb 3+ co-doped glasses and glass–ceramics with 980 nm laser excitation varying the laser power and concentration of Er 3+ ions. Results showed that the upconversion luminescence intensity was enhanced by ten times in SNT glass–ceramics compared to that in the SNT glasses. Decay curves give evidence of high performance of glass–ceramics compared to glasses due to ceramization and structural changes. Temperature dependent visible upconversion was performed to test the ability of efficient SNT glass–ceramic at low temperatures and variation of upconversion intensities was studied

Controlled fabrication of luminescent and magnetic nanocomposites

Science.gov (United States)

Ma, Yingxin; Zhong, Yucheng; Fan, Jing; Huang, Weiren

2018-03-01

Luminescent and magnetic multifunctional nanocomposite is in high demand and widely used in many scales, such as drug delivery, bioseparation, chemical/biosensors, and so on. Although lots of strategies have been successfully developed for the demand of multifunctional nanocomposites, it is not easy to prepare multifunctional nanocomposites by using a simple method, and satisfy all kinds of demands simultaneously. In this work, via a facile and versatile method, luminescent nanocrystals and magnetic nanoparticles were successfully synthesized through self-assembly under vigorous stirring and ultrasonic treatment. These multifunctional nanocomposites are not only water stable but also find wide application such as magnetic separation and concentration with a series of moderate speed, multicolor fluorescence at different emission wavelength, high efficiency of the excitation and emission, and so on. By changing different kinds of luminescent nanocrystals and controlling the amount of luminescent and magnetic nanoparticles, a train of multifunctional nanocomposites was successfully fabricated via a versatile and robust method.

Analysis of subnanosecond fluorescence decay curves with a 5GHz real time detection system

International Nuclear Information System (INIS)

Cunin, B.; Heisel, F.; Knispel, G.; Miehe, J.A.; Sipp, B.

1975-01-01

This paper presents a detailed description and a review on the characteristics of a fast vacuum photoelectric cell associated with a high speed cathode ray tube. In addition, this system is used to measure short-lived fluorescence decay times [fr

Solubility limit and luminescence properties of Eu{sup 3+} ions in Al{sub 2}O{sub 3} powder

Energy Technology Data Exchange (ETDEWEB)

Onishi, Yuya; Nakamura, Toshihiro, E-mail: tnakamura@gunma-u.ac.jp; Adachi, Sadao, E-mail: adachi@gunma-u.ac.jp

2016-08-15

Al–Eu–O compounds are synthesized from Al{sub 2}O{sub 3}:Eu{sub 2}O{sub 3}=(1–x):x mixtures (x=0–0.15) by the metal organic decomposition method and subsequently calcined at various temperatures from T{sub c}=750 to 1200 °C in dry O{sub 2} atmosphere. The structural and luminescence properties of these compounds are investigated using X-ray diffraction analysis, photoluminescence (PL) analysis, PL excitation spectroscopy, and luminescence lifetime measurements. The present study focuses on the effects of the Eu{sub 2}O{sub 3} addition (x) on the material and phosphor properties of Al{sub 2}O{sub 3}:Eu{sup 3+}. The stable phase of α-Al{sub 2}O{sub 3} is synthesized at T{sub c}>1100 °C and cubic γ-Al{sub 2}O{sub 3} phase at T{sub c}≤1100 °C. The calcination temperature dependence of the PL intensity yields an activation of E{sub a}~0.8 eV for Eu{sup 3+} ions in the Al{sub 2}O{sub 3} host. The luminescence decay time is determined to be ~0.8 ms, independent of x. Temperature dependence of the PL intensity at T=20–450 K exhibits thermal quenching behavior with energies of 17 meV and 0.28 eV at low (<200 K) and high temperatures (>200 K), respectively. The solubility limit of Eu{sup 3+} ions in α-Al{sub 2}O{sub 3} is determined to be ~1%. The schematic energy-level diagram of Eu{sup 3+} in α-Al{sub 2}O{sub 3} is also proposed for the sake of a better understanding of the luminescence process of this phosphor system.

The analysis of time-resolved optically stimulated luminescence: I. Theoretical considerations

International Nuclear Information System (INIS)

Chithambo, M L

2007-01-01

This is the first of two linked papers on the analysis of time-resolved optically stimulated luminescence. This paper focusses on a theoretical basis of analytical methods and on methods for interpretation of time-resolved luminescence spectra and calculation of luminescence throughput. Using a comparative analysis of the principal features of time-resolved luminescence and relevant analogues from steady state optical stimulation, formulae for configuring a measurement system for optimum performance are presented. We also examine the possible use of stretched-exponential functions for analysis of time-resolved optically stimulated luminescence spectra

Luminescence and radiocarbon dating of raised beach sediments, Bunger Hills, East Antarctica

International Nuclear Information System (INIS)

Augustinus, P.C.; Duller, G.A.T.

2002-01-01

Luminescence and radiocarbon dating of raised marine sediments from the Bunger Hills, East Antarctica, demonstrates that luminescence methods can be applied to such poorly bleached sediments as long as the luminescence behaviour of the sediments is understood. This is essential as the complete zeroing of the luminescence signal due to light exposure is required to allow an accurate age for the sediment accumulation. Unfortunately, independent checks on the luminescence ages are rare. In the present study, some independent age control is provided by AMS radiocarbon ages from shell obtained from and adjacent to the luminescence dated horizons, although the radiocarbon ages may suffer to some degree from variability in the marine reservoir effect. Application of the single aliquot luminescence technique to feldspar grains from the marine sediments demonstrated that the luminescence behaviour of the sediments was complex. For each sample, 18 replicate paleodose estimates were used to demonstrate whether the sediments were well bleached before deposition. Optically, well-bleached samples give younger luminescence ages, whilst poorly bleached samples often give excessively old ages compared to the associated radiocarbon-dated material. (author)

Magnetic-luminescent spherical particles synthesized by ultrasonic spray pyrolysis

International Nuclear Information System (INIS)

Michel, Norma L; Hirata, Gustavo A; Flores, Dora L

2015-01-01

The combination of magnetic and luminescent properties in a single particle system, opens-up a wide range of potential applications in biotechnology and biomedicine. In this work, we performed the synthesis of magnetic-luminescent Gd 2 O 3 :Eu 3+ @Fe 2 O 3 particles by ultrasonic spray pyrolysis performed in a tubular furnace. In order to achieve the composite formation, commercial superparamagnetic Fe 3 O 4 nanoparticles were coated with a luminescent Eu 3+ -doped Gd 2 O 3 shell in a low-cost one-step process. The spray pyrolysis method yields deagglomerated spherical shape magneto/luminescent particles. The photoluminescence spectra under UV excitation (λ Exc = 265 nm) of the magnetic Gd 2 O 3 :Eu 3+ @Fe 2 O 3 compound showed the characteristic red emission of Eu 3+ (λ Em = 612 nm). This magneto/luminescent system will find applications in biomedicine and biotechnology. (paper)

Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars

DEFF Research Database (Denmark)

Pagonis, Vasilis; Ankjærgaard, Christina; Jain, Mayank

2016-01-01

Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IR...

On the doubly ionized states of Ar2 and their intra- and interatomic decay to Ar23+

International Nuclear Information System (INIS)

Stoychev, Spas D.; Kuleff, Alexander I.; Tarantelli, Francesco; Cederbaum, Lorenz S.

2008-01-01

Potential energy curves of the Auger state Ar + (2p -1 )-Ar, the different one- and two-site dicationic states Ar 2 ++ (with energies in the range of 32-77 eV), and the lowest two-site tricationic states Ar ++ -Ar + (with energies in the range of 64-76 eV) computed using elaborated ab initio methods are reported. The accessible relaxation channels of the electronic states of Ar ++ -Ar populated by Auger decay are studied. In particular, we study in detail the interatomic Coulombic decay following the population of one-site satellite states of Ar ++ (3s -1 3p -1 )-Ar recently observed experimentally. Other relaxation pathways of Ar ++ -Ar, including radiative charge transfer, nuclear dynamics through curve crossing, and intra-atomic decay processes are also investigated

Exciton luminescence in CdxMn1-xTe compounds

International Nuclear Information System (INIS)

Caraman, M.; Gashin, P.; Metelitsa, Snejana; Nicorici, Valentina; Nicorici, A.

2002-01-01

The Cd x Mn 1-x Te (0.5 7 W/cm 2 . The luminescence spectra were observed at 78 K. The results of the study had shown that the presence of relatively narrow luminescence peaks localized in the region of the fundamental absorption edge is characteristic for these spectra and for the majority of the crystals a wide maximum in the long wavelength region is observed. The luminescence maxima with an accuracy of ∼ 5 meV correspond to the resonance energy of the excitons of the state with n=1 determined from the absorption spectra. Hence, these maxima can be considered as exciton luminescence stimulated either by the excitons of the state n=1 or bounded to the exciton ionization centers. From the analysis of the absorption and exciton luminescence spectra one can make a conclusion about the fact that the homogeneity extent of the crystals decreases from CdTe to the compounds with x= 0.8 - 0.7 and slightly increases at the x decrease to 0.5. The exciton luminescence lines in CdTe and Cd 0.99 Mn 0.01 Te crystals is shifting by 7 - 10 meV relatively to the lines of free excitons absorption. This fact is explained by the fact that in these crystals, probably, excitons bounding to the lattice inherited defects with the binding energy of 7 - 10 meV participate in the luminescence. In the long wavelength region a wide peak is observed on which the impurity lines are not displayed. In the luminescence spectra of CdTe with 0.1%. As crystals three maxima at 1.51 eV, 1.46 eV and 1.42 eV are revealed. For pure CdTe the maximum at 1.4 eV is also revealed. These maxima are explained by the luminescence through the recombination levels localized at 0.46 eV. (authors)

DECSERVIS-2: A tool for natural decay series mass flow simulation

International Nuclear Information System (INIS)

Azzam, Saad; Suksi, Juhani; Ammann, Michael

2009-01-01

After the publication of 'DECSERVIS: a tool for radioactive decay series visualisation' we have further developed our DECSERVIS software. With the new tool DECSERVIS-2 one can simulate radioactive decay chains in open systems, i.e. when the concentrations of nuclides change also due to mass flows. Decay chains can be simulated under continuous and successive nuclide mass flow events into and out from the system and in freely determined time intervals. Simulation output for the entire decay chain (nuclide activity, mass, number of nuclides, nuclide ratios) can be presented as a function of time with various graphical presentations such as solid curve and column diagrams or animation. In this paper we introduce DECSERVIS-2 and demonstrate its use with simulation examples. DECSERVIS-2 is easy to use and has been designed with an eye on the demands of teaching.

Study of the liquid water luminescence induced by charged particles

International Nuclear Information System (INIS)

Rusu, Mircea; Stere, Oana; Haiduc, Maria; Caramete, Laurentiu

2004-01-01

Many observations suggested that liquid water (with impurities) could give a luminescence output when irradiated with charged particles. We investigate theoretical and practical possibility of detecting such luminescence. Preliminary results on this possibility are presented, and a layout of the device proposed for measuring luminescence is given. (authors)

Hydrothermal synthesis, characterization, and luminescence of Ca{sub 2}B{sub 2}O{sub 5}:RE (RE = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanofibers

Energy Technology Data Exchange (ETDEWEB)

Yang, Li; Wan, Yingpeng; Li, Yuze; Pu, Yinfu; Huang, Yanlin, E-mail: huang@suda.edu.cn [Soochow University, State and Local Joint Engineering Laboratory for Novel Functional Polymeric Materials, College of Chemistry, Chemical Engineering and Materials Science (China); Chen, Cuili; Seo, Hyo Jin, E-mail: hjseo@pknu.ac.kr [Pukyong National University, Department of Physics and Interdisciplinary Program of Biomedical Engineering (Korea, Republic of)

2016-04-15

Ca{sub 2}B{sub 2}O{sub 5}:RE (RE = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanofibers were synthesized by the hydrothermal reaction method. The structural refinement was conducted on the base of the X-ray powder diffraction (XRD) measurements. The surface properties of the Ca{sub 2}B{sub 2}O{sub 5}:RE (RE = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanofibers were investigated by the measurements such as the scanning electron microscope (SEM), transmission electron microscope (TEM), and the energy dispersive spectrum (EDS). The nanofiber has a diameter of about 100 nm and a length of several micrometers. The luminescence properties such as photoluminescence excitation (PLE) and emission spectra (PL), decay lifetime, color coordinates, and the absolute internal quantum efficiency (QE) were reported. Ca{sub 2}B{sub 2}O{sub 5}:Eu{sup 3+} nanofibers show the red luminescence with CIE coordinates of (x = 0.41, y = 0.51) and the luminescence lifetime of 0.63 ms. The luminescence of Ca{sub 2}B{sub 2}O{sub 5}:Tb{sup 3+} nanofibers is green color (x = 0.29, y = 0.53) with the lifetime of 2.13 ms. However, Dy{sup 3+}-doped Ca{sub 2}B{sub 2}O{sub 5} nanofibers present a single-phase white-color phosphor with the fluorescence decay of 3.05 ms. Upon near-UV excitation, the absolute quantum efficiency is measured to be 65, 35, and 37 % for Eu{sup 3+}-, Tb{sup 3+}-, Dy{sup 3+}-doped Ca{sub 2}B{sub 2}O{sub 5} nanofibers, respectively. It is suggested that Ca{sub 2}B{sub 2}O{sub 5}:RE (RE = Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+}) nanofibers could be an efficient phosphor for lighting and display.

Flight testing of a luminescent surface pressure sensor

Science.gov (United States)

Mclachlan, B. G.; Bell, J. H.; Espina, J.; Gallery, J.; Gouterman, M.; Demandante, C. G. N.; Bjarke, L.

1992-01-01

NASA ARC has conducted flight tests of a new type of aerodynamic pressure sensor based on a luminescent surface coating. Flights were conducted at the NASA ARC-Dryden Flight Research Facility. The luminescent pressure sensor is based on a surface coating which, when illuminated with ultraviolet light, emits visible light with an intensity dependent on the local air pressure on the surface. This technique makes it possible to obtain pressure data over the entire surface of an aircraft, as opposed to conventional instrumentation, which can only make measurements at pre-selected points. The objective of the flight tests was to evaluate the effectiveness and practicality of a luminescent pressure sensor in the actual flight environment. A luminescent pressure sensor was installed on a fin, the Flight Test Fixture (FTF), that is attached to the underside of an F-104 aircraft. The response of one particular surface coating was evaluated at low supersonic Mach numbers (M = 1.0-1.6) in order to provide an initial estimate of the sensor's capabilities. This memo describes the test approach, the techniques used, and the pressure sensor's behavior under flight conditions. A direct comparison between data provided by the luminescent pressure sensor and that produced by conventional pressure instrumentation shows that the luminescent sensor can provide quantitative data under flight conditions. However, the test results also show that the sensor has a number of limitations which must be addressed if this technique is to prove useful in the flight environment.

Recent Advances on Luminescent Enhancement-Based Porous Silicon Biosensors.

Science.gov (United States)

Jenie, S N Aisyiyah; Plush, Sally E; Voelcker, Nicolas H

2016-10-01

Luminescence-based detection paradigms have key advantages over other optical platforms such as absorbance, reflectance or interferometric based detection. However, autofluorescence, low quantum yield and lack of photostability of the fluorophore or emitting molecule are still performance-limiting factors. Recent research has shown the need for enhanced luminescence-based detection to overcome these drawbacks while at the same time improving the sensitivity, selectivity and reducing the detection limits of optical sensors and biosensors. Nanostructures have been reported to significantly improve the spectral properties of the emitting molecules. These structures offer unique electrical, optic and magnetic properties which may be used to tailor the surrounding electrical field of the emitter. Here, the main principles behind luminescence and luminescence enhancement-based detections are reviewed, with an emphasis on europium complexes as the emitting molecule. An overview of the optical porous silicon microcavity (pSiMC) as a biosensing platform and recent proof-of-concept examples on enhanced luminescence-based detection using pSiMCs are provided and discussed.

X-ray luminescent glasses

International Nuclear Information System (INIS)

Takahashi, T.; Yamada, O.

1981-01-01

X-ray luminescent glasses comprising a divalent cation such as an alkaline earth metal or other divalent cations such as pb, cd, or zn, and certain rare earth metaphosphates are suitable as vitreous, x-ray phosphors or x-ray luminescent glass fibers in an x-ray intensifying screen. The glasses have the composition n(Mo X p2o5)((1-y)tb2o3 X yce2o3 X 3p2o5) wherein N is greater than zero but less than or equal to 16, M is an alkaline earth metal or other divalent cation such as pb, cd, or zn, and Y is greater than or equal to zero but less than one

Determination of uranium by luminescent method (tablet variant)

International Nuclear Information System (INIS)

Sergeev, A.N.; Yufa, B.Ya.

1985-01-01

A new tablet variant of luminescent determination of uranium in rocks is developed. The analytical process includes the following operations: sample decomposition, uranium separation from luminescence quencher impurities, preparation of luminescent sample (tablet), photometry of the tablet. The method has two variants developed: the first one is characterized by a more hard decomposition, sample mass being 0.2 g; the second variant has a better detection limit (5x10 -6 %), the sample mass being 0.2-1 g. Procedures of the sample preparation for both variants of analysis are described

Characteristics of pulsed photo-stimulated luminescence and thermoluminescence for the identification of gamma irradiated poultry eggs

International Nuclear Information System (INIS)

Bhatti, I.A.; Kwon, J.-H.

2006-01-01

Pulsed photo-stimulated luminescence (PPSL) is a simple screening method that can be employed qualitatively at the spot for the detection of eggs treated with ionizing radiation. In spite of the variations in the results during storage, the eggs of ostrich, duck, hen and quail irradiated to doses of 0, 1, 2 and 3 kGy, most of the samples were correctly identified up to six months during storage after irradiation. Thermoluminescence (TL) technique was also tried by using eggshells in order to confirm the PPSL results. TL glow curves were recorded between the temperatures 50 to 400 degree C at the rate of 5 degree per second for all the control and irradiated samples. On the basis of integrated areas of first glow curves (TL1), the glow curve ratios (TL1/TL2) and the shapes of maxima of TL1, the irradiation treatment of all the eggs was confirmed. Furthermore, the presence of calcite and aragonite minerals that cause the TL signal in the eggshells were studied using X-ray diffraction spectrometry. (authors)

Characteristics of pulsed photo-stimulated luminescence and thermoluminescence for the identification of gamma irradiated poultry eggs

International Nuclear Information System (INIS)

Bhatti, I.A.; Kwon, J.-H.; Ur-rehman, S.

2007-01-01

Pulsed photo-stimulated luminescence (PPSL) is a simple screening method that can be employed qualitatively at the spot for the detection of eggs treated with ionizing radiation. Due to the variations in the results during storage, the eggs of ostrich, duck, hen, and quail were irradiated to doses of 0, 1, 2, and 3 kGy. Most of the samples were incorrectly identified during storage after four months of irradiation. Thermoluminescence (TL) technique was also tried by using egg shells in order to confirm the irradiation treatment in eggs. TL glow curves were recorded between the temperatures 50 degree C to 400 degree C at the rate of 5 degree/s for all the control and irradiated samples. On the basis of integrated areas of first glow curves (TL1), the glow curve ratios (TL1/TL2) and the shapes of maxima of TL1, the irradiation treatment of all the eggs was confirmed. Furthermore, the presence of calcite and aragonite minerals that cause the TL signal in the egg shells were studied using X-ray diffraction spectrometry. (authors)

Fabrication and Spectral Properties of Wood-Based Luminescent Nanocomposites

Directory of Open Access Journals (Sweden)

Xianjun Li

2014-01-01

Full Text Available Pressure impregnation pretreatment is a conventional method to fabricate wood-based nanocomposites. In this paper, the wood-based luminescent nanocomposites were fabricated with the method and its spectral properties were investigated. The results show that it is feasible to fabricate wood-based luminescent nanocomposites using microwave modified wood and nanophosphor powders. The luminescent strength is in positive correlation with the amount of phosphor powders dispersed in urea-formaldehyde resin. Phosphors absorb UV and blue light efficiently in the range of 400–470 nm and show a broad band of bluish-green emission centered at 500 nm, which makes them good candidates for potential blue-green luminescent materials.

Enhancement of Cerenkov luminescence imaging by dual excitation of Er(3+,Yb(3+-doped rare-earth microparticles.

Directory of Open Access Journals (Sweden)

Xiaowei Ma

Full Text Available Cerenkov luminescence imaging (CLI has been successfully utilized in various fields of preclinical studies; however, CLI is challenging due to its weak luminescent intensity and insufficient penetration capability. Here, we report the design and synthesis of a type of rare-earth microparticles (REMPs, which can be dually excited by Cerenkov luminescence (CL resulting from the decay of radionuclides to enhance CLI in terms of intensity and penetration.Yb(3+- and Er(3+- codoped hexagonal NaYF4 hollow microtubes were synthesized via a hydrothermal route. The phase, morphology, and emission spectrum were confirmed for these REMPs by power X-ray diffraction (XRD, scanning electron microscopy (SEM, and spectrophotometry, respectively. A commercial CCD camera equipped with a series of optical filters was employed to quantify the intensity and spectrum of CLI from radionuclides. The enhancement of penetration was investigated by imaging studies of nylon phantoms and nude mouse pseudotumor models.the REMPs could be dually excited by CL at the wavelengths of 520 and 980 nm, and the emission peaks overlaid at 660 nm. This strategy approximately doubled the overall detectable intensity of CLI and extended its maximum penetration in nylon phantoms from 5 to 15 mm. The penetration study in living animals yielded similar results.this study demonstrated that CL can dually excite REMPs and that the overlaid emissions in the range of 660 nm could significantly enhance the penetration and intensity of CL. The proposed enhanced CLI strategy may have promising applications in the future.

K2SO4 and LiKSO4 crystals luminescence

International Nuclear Information System (INIS)

Charapiev, B.; Nurakhmetov, T.N.

2002-01-01

In the paper a nature of X-ray and tunnel luminescence in LiKSO 4 and Li 2 SO 4 ·H 2 O crystals are discussed. It is shown, that X-ray luminescence and Li 2 SO 4 ·H 2 O and LiKSO 4 appeals in the result of electrons recombination with auto-localized holes (SO 4 - ), and tunnel luminescence appeals at electrons transfer from ground state of electron center into hole center capture ground state. Under heating of irradiated crystal de-localized holes at recombination moment with electron capture centers are forming auto-localized excitons, which are disintegrating with photon emitting, and so X-ray luminescence spectrum and thermally induces luminescence peaks are coinciding. Nature of radiation appealing in LiKSO 4 at ultraviolet excitation is discussing

Time-resolved luminescence from quartz: An overview of contemporary developments and applications

Energy Technology Data Exchange (ETDEWEB)

Chithambo, M.L., E-mail: m.chithambo@ru.ac.za [Department of Physics and Electronics, Rhodes University, PO BOX 94, Grahamstown 6140 (South Africa); Ankjærgaard, C. [Soil Geography and Landscape Group, Wageningen University Netherlands Centre for Luminescence Dating, Droevendaalsesteeg 3, 6708 PB Wageningen, The Netherlands (Netherlands); Pagonis, V. [McDaniel College, Physics Department, Westminster, MD 21157 (United States)

2016-01-15

Time-resolved optical stimulation of luminescence has become established as a key method for measurement of optically stimulated luminescence from quartz, feldspar and α-Al{sub 2}O{sub 3}:C, all materials of interest in dosimetry. The aim of time-resolved optical stimulation is to separate in time the stimulation and emission of luminescence. The luminescence is stimulated from a sample using a brief light pulse and the emission monitored during stimulation in the presence of scattered stimulating light or after pulsing, over photomultiplier noise only. Although the use of the method in retrospective dosimetry has been somewhat limited, the technique has been successfully applied to study mechanisms in the processes leading up to luminescence emission. The main means for this has been the temperature dependence of the luminescence intensity as well as the luminescence lifetimes determined from time-resolved luminescence spectra. In this paper we review some key developments in theory and applications to quartz including methods of evaluating lifetimes, techniques of evaluating kinetic parameters using both the dependence of luminescence intensity and lifetime on measurement temperature, and of lifetimes on annealing temperature. We then provide an overview of some notable applications such as separation of quartz signals from a quartz–feldspar admixture and the utility of the dynamic throughput, a measure of luminescence measured as a function of the pulse width. The paper concludes with some suggestions of areas where further exploration would advance understanding of dynamics of luminescence in quartz and help address some outstanding problems in its application.

Luminescence of Bi3+ ions in Y3Al5O12:Bi single crystalline films

International Nuclear Information System (INIS)

Zorenko, Yu.; Gorbenko, V.; Voznyak, T.; Vistovsky, V.; Nedilko, S.; Nikl, M.

2007-01-01

The absorption and cathodoluminescence spectra of single crystalline films (SCF) of Y 3 Al 5 O 12 :Bi garnet depending on Bi concentration were analyzed. For consideration of the nature of the UV and visible Bi-related emission bands the time-resolved luminescence of Bi 3+ (ns 2 ) ions in YAG:Bi SCF was studied at 10 K under excitation by synchrotron radiation. The difference in the excitation spectra and emission decay of the UV and visible bands has been explained via radiative relaxation from the 3 P 1,0 excited states to the 1 S 0 ground state of the isolated and pair/clustered Bi 3+ emission centers in the garnet lattice, respectively

Luminescence properties of some food dye-stuffs

International Nuclear Information System (INIS)

Astanov, S.Kh.; Muminova, Z.A.; Urunov, R.G.

2004-01-01

The luminescence properties of the natural food dye-stuffs and vitamins in temperature range of 300-5.2 K are studied. On the basis of experimental data on quantum yields of the fluorescence, trans-cis-isomerization and luminescence of the molecular oxygen the main ways of the inactivation of electronic excitations in researching compounds have been defined. (author)

Method and apparatus for reducing solvent luminescence background emissions

Energy Technology Data Exchange (ETDEWEB)

Affleck, Rhett L. (Los Alamos, NM); Ambrose, W. Patrick (Los Alamos, NM); Demas, James N. (Charlottesville, VA); Goodwin, Peter M. (Jemez Springs, NM); Johnson, Mitchell E. (Pittsburgh, PA); Keller, Richard A. (Los Alamos, NM); Petty, Jeffrey T. (Los Alamos, NM); Schecker, Jay A. (Santa Fe, NM); Wu, Ming (Los Alamos, NM)

1998-01-01

The detectability of luminescent molecules in solution is enhanced by reducing the background luminescence due to impurity species also present in the solution. A light source that illuminates the solution acts to photolyze the impurities so that the impurities do not luminesce in the fluorescence band of the molecule of interest. Molecules of interest may be carried through the photolysis region in the solution or may be introduced into the solution after the photolysis region.

Luminescence properties and gamma-ray response of the Ce and Ca co-doped (Gd,Y)F3 single crystals

International Nuclear Information System (INIS)

Kamada, Kei; Yanagida, Takayuki; Fujimoto, Yutaka; Fukabori, Akihiro; Yoshikawa, Akira; Nikl, Martin

2011-01-01

The Ca0.5% and Ce1%, 3%, 7%, 10% co-doped Gd 0.5 Y 0.5 F 3 single crystals were grown by the μ-PD method. In the Ca0.5% and Ce3% co-doped sample, Ce 3+ -perturbed luminescence at 380 nm was observed with 32.4 ns photoluminescence decay time. The energy transfer in the sequence of the regular Ce 3+ → (Gd 3+ ) n → the perturbed Ce 3+ sites was evidenced through observation of decay time shortening of the regular Ce 3+ and Gd 3+ centers and the change between the Gd 3+ and Ce 3+ -perturbed emission intensity. The gamma-ray excited scintillation response of the Ca0.5%, Ce7% co-doped Gd 0.5 Y 0.5 F 3 sample was investigated with the help of the pulse height spectra and the light yield, energy resolution and non-proportionality was evaluated in the interval of energies of 59.4-1274 keV.

Development of luminescent pH sensor films for monitoring bacterial growth through tissue.

Science.gov (United States)

Wang, Fenglin; Raval, Yash; Chen, Hongyu; Tzeng, Tzuen-Rong J; DesJardins, John D; Anker, Jeffrey N

2014-02-01

Although implanted medical devices (IMDs) offer many benefits, they are susceptible to bacterial colonization and infections. Such infections are difficult to treat because bacteria could form biofilms on the implant surface, which reduce antibiotics penetration and generate local dormant regions with low pH and low oxygen. In addition, these infections are hard to detect early because biofilms are often localized on the surface. Herein, an optical sensor film is developed to detect local acidosis on an implanted surface. The film contains both upconverting particles (UCPs) that serve as a light source and a pH indicator that alters the luminescence spectrum. When irradiated with 980 nm light, the UCPs produce deeply penetrating red light emission, while generating negligible autofluorescence in the tissue. The basic form of the pH indicator absorbs more of upconversion luminescence at 661 nm than at 671 nm and consequently the spectral ratio indicates pH. Implanting this pH sensor film beneath 6-7 mm of porcine tissue does not substantially affect the calibration curve because the peaks are closely spaced. Furthermore, growth of Staphylococcus epidermidis on the sensor surface causes a local pH decrease that can be detected non-invasively through the tissue. Copyright © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Luminescent properties of composite scintillators based on PPO and o-POPOP doped SiO{sub 2} xerogel matrices

Energy Technology Data Exchange (ETDEWEB)

Viagin, O., E-mail: viagin@isma.kharkov.ua [Institute for Scintillation Materials of NAS of Ukraine, 60 Science Ave., 61001 Kharkiv (Ukraine); Masalov, A.; Bespalova, I.; Zelenskaya, O.; Tarasov, V.; Seminko, V.; Voloshina, L. [Institute for Scintillation Materials of NAS of Ukraine, 60 Science Ave., 61001 Kharkiv (Ukraine); Zorenko, Yu. [Institute of Physics of Kazimierz Wielki University of Bydgoszcz, 2 Powstańców Wielkopolskich str., 85-090 Bydgoszcz (Poland); Malyukin, Yu. [Institute for Scintillation Materials of NAS of Ukraine, 60 Science Ave., 61001 Kharkiv (Ukraine)

2016-11-15

New composite scintillation detectors were obtained by incorporation of PPO and o-POPOP organic scintillators into porous sol–gel silica matrices. Composites possess high photoluminescence intensity and decay time in nanosecond range. The absolute light yield of composite scintillators at excitation by alpha-radiation is about 4000–5000 photons/MeV and the pulse–height resolution is about 30%. The investigations of time-resolved luminescence of composites performed under excitation by synchrotron radiation in the 3.7–25 eV range have shown that the non-radiative energy transfer between host matrix and dopant molecules occurs via singlet states of SiO{sub 2} oxygen-deficient centers.

Luminescent materials and their applications

CERN Document Server

Virk, Hardev Singh

2015-01-01

It is pertinent to note that Luminescence phenomenon has once again occupied a central stage with the announcement of Nobel Prize in October 2014 to three Japanese scientists. The discovery of Galium Nitride proved to be a revolutionary step forward in creation of Blue LEDs. With the advent of LED lamps we now have more long-lasting and more efficient alternatives to older light sources. The Volume under reference consists of 9 Chapters, written by experts in the area of Luminescent Materials. First 5 Chapters are contributed as Review Papers and the last 4 are based on Research Papers.Chapter

Paper-based biodetection using luminescent nanoparticles.

Science.gov (United States)

Ju, Qiang; Noor, M Omair; Krull, Ulrich J

2016-05-10

Point-of-care and in-field technologies for rapid, sensitive and selective detection of molecular biomarkers have attracted much interest. Rugged bioassay technology capable of fast detection of markers for pathogens and genetic diseases would in particular impact the quality of health care in the developing world, but would also make possible more extensive screening in developed countries to tackle problems such as those associated with water and food quality, and tracking of infectious organisms in hospitals and clinics. Literature trends indicate an increasing interest in the use of nanomaterials, and in particular luminescent nanoparticles, for assay development. These materials may offer attributes for development of assays and sensors that could achieve improvements in analytical figures of merit, and provide practical advantages in sensitivity and stability. There is opportunity for cost-efficiency and technical simplicity by implementation of luminescent nanomaterials as the basis for transduction technology, when combined with the use of paper substrates, and the ubiquitous availability of cell phone cameras and associated infrastructure for optical detection and transmission of results. Luminescent nanoparticles have been described for a broad range of bioanalytical targets including small molecules, oligonucleotides, peptides, proteins, saccharides and whole cells (e.g., cancer diagnostics). The luminescent nanomaterials that are described herein for paper-based bioassays include metal nanoparticles, quantum dots and lanthanide-doped nanocrystals. These nanomaterials often have broad and strong absorption and narrow emission bands that improve opportunity for multiplexed analysis, and can be designed to provide emission at wavelengths that are efficiently processed by conventional digital cameras. Luminescent nanoparticles can be embedded in paper substrates that are designed to direct fluid flow, and the resulting combination of technologies can offer

Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

Science.gov (United States)

Dieu, Bjorn; Roeffaers, Maarten B.J.; Hofkens, Johan

2016-01-01

Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film. PMID:27911397

Retrospective dosimetry using Japanese brick quartz: A way forward despite an unstable fast decaying OSL signal

DEFF Research Database (Denmark)

Fujita, Hiroki; Jain, Mayank; Murray, A.S.

2011-01-01

signals has been carried out towards identification of common source traps. It is observed that OSL from Japanese brick quartz shows unusual luminescence characteristics; in particular, the initial fast decaying OSL signal contains a dominant (>90%) thermally unstable component related to the 85 °C TL...... peak, which necessitates a prior heat treatment. A single-aliquot regenerative-dose (SAR) protocol is developed and tested using thermal treatments intended to isolate a stable dosimetric signal. A minimum detection limit of 65 mGy is then estimated using this protocol. Following irradiation using 60Co...... of Japanese brick quartz examined here can be used to derive precise estimates of accident dose, and, possibly to distinguish between sources of gamma radiation in a nuclear accident. To our knowledge, this is the first report on the existence of an unstable fast decaying OSL signal in quartz derived from...

Energy localization and decay in highly ionic crystals

International Nuclear Information System (INIS)

Williams, R.T.; Thoma, E.D.; Bunton, P.H.

1994-01-01

Luminescence from localized states in pure wide-gap crystals is examined from the perspective of modern fast scintillator requirements. Recent advances in the understanding of self-trapped excitons are summarized with regard to excited-state configurations, spectra, and luminescence efficiency. As an example, the fast luminescence of partially quenched type I STEs (self-trapped excitons) in RbI offers tunable-lifetime subnanosecond pulses which could be useful for timing applications. The possible role of hole localization in cross luminescence is discussed. Stokes-shifted luminescence in some pure rare-earth fluoride crystals probably originates from self-trapped excitons of forms to be discussed

[Synthesis of reserve polyhydroxyalkanoates by luminescent bacteria].

Science.gov (United States)

Boiandin, A N; Kalacheva, G S; Rodicheva, E K; Volova, T G

2008-01-01

The ability of marine luminescent bacteria to synthesize polyesters of hydroxycarboxylic acids (polyhydroxyalkanoates, PHA) as reserve macromolecules was studied. Twenty strains from the collection of the luminescent bacteria CCIBSO (WDSM839) of the Institute of Biophysics, Siberian Branch, Russian Academy of Sciences, assigned to different taxa (Photobacterium leiognathi, Ph. phosphoreum, Vibrio harveyi, and V. fischeri) were analyzed. The most productive strains were identified, and the conditions ensuring high polymer yields in batch culture (40-70% of the cell dry mass weight) were determined. The capacity of synthesizing two- and three-component polymers containing hydroxybutyric acid as the main monomer and hydroxyvaleric and hydroxyhexanoic acids was revealed in Ph. leiognathi and V. harveyi strains. The results allow luminescent microorganisms to be regarded as new producers of multicomponent polyhydroxyalkanoates.

Photoluminescence decay lifetime measurements of hemicyanine derivatives of different alkyl chain lengths

International Nuclear Information System (INIS)

Shim, Taekyu; Lee, Myounghee; Kim, Sungho; Sung, Jaeho; Rhee, Bum Ku; Kim, Doseok; Kim, Hyunsung; Yoon, Kyung Byung

2004-01-01

The fluorescence upconversion setup for the detection of photoluminescence (PL) decay lifetime with subpicosecond time resolution was constructed, and the photoluminescence phenomena of several hemicyanine dyes with alkyl chains of different chain lengths tethered to the N atom of the pyridine moiety (HC-n, n=6, 15, 22) in methanol were investigated. The average decay lifetimes of the solutions determined from the measured data by multi-order exponential decay curve fitting were ∼27 ps at the PL peak wavelength. It was found that the PL decay properties did not depend on the alkyl chain length in the molecule, implying that the twist of the alkylpyridinium ring of the molecule is not possible as a nonfluorescing relaxation pathway. The time-dependent PL spectra constructed from the PL lifetime data showed the dynamic Stokes shift of ∼1000 cm -1

Influence of Nanosized Silicon Oxide on the Luminescent Properties of ZnO Nanoparticles

Directory of Open Access Journals (Sweden)

Vitaliy Shvalagin

2016-01-01

Full Text Available For practical use of nanosized zinc oxide as the phosphor its luminescence quantum yields should be maximized. The aim of this work was to enhance luminescent properties of ZnO nanoparticles and obtain high-luminescent ZnO/SiO2 composites using simpler approaches to colloidal synthesis. The luminescence intensity of zinc oxide nanoparticles was increased about 3 times by addition of silica nanocrystals to the source solutions during the synthesis of ZnO nanoparticles. Then the quantum yield of luminescence of the obtained ZnO/SiO2 composites is more than 30%. Such an impact of silica is suggested to be caused by the distribution of ZnO nanocrystals on the surface of silica, which reduces the probability of separation of photogenerated charges between the zinc oxide nanoparticles of different sizes, and as a consequence, there is a significant increase of the luminescence intensity of ZnO nanoparticles. This way of increasing nano-ZnO luminescence intensity facilitates its use in a variety of devices, including optical ultraviolet and visible screens, luminescent markers, antibacterial coatings, luminescent solar concentrators, luminescent inks for security printing, and food packaging with abilities of informing consumers about the quality and safety of the packaged product.

On the correlation between annealing and variabilities in pulsed-luminescence from quartz

International Nuclear Information System (INIS)

Chithambo, M.L.

2006-01-01

Properties of luminescence lifetimes in quartz related to annealing between 500 and 900 deg. C have been investigated. The luminescence was pulse-stimulated at 470nm from sets of granular quartz annealed at 500, 600, 700, 800, and 900 deg. C. The lifetimes decrease with annealing temperature from about 42 to 33μs when the annealing temperature is increased from 500 to 900 deg. C. Luminescence lifetimes are most sensitive to duration of annealing at 600 deg. C, decreasing from 40.2+/-0.7μs by as much as 7μs when the duration of annealing is changed from 10 to 60min. However, at 800-900 deg. C lifetimes are essentially independent of annealing temperature at about 33μs. Increasing the exciting beta dose causes an increase in the lifetimes of the stimulated luminescence in the sample annealed at 800 deg. C but not in those annealed at either 500 or 600 deg. C. The temperature-resolved distribution of luminescence lifetimes is affected by thermal quenching of luminescence. These features may be accounted for with reference to two principal luminescence centres involved in the luminescence emission process

Luminescence characteristics of dental ceramics for retrospective dosimetry: a preliminary study

International Nuclear Information System (INIS)

Bailiff, I.K.; Correcher, V.; Delgado, A.; Goksu, Y.; Huebner, S.

2002-01-01

Ceramic materials that are widely employed in dental prosthetics and repairs exhibit luminescent properties. Because of their use in the body, these materials are potentially of interest in situations where retrospective dosimetry for individuals is required but where monitoring was not planned. The luminescent properties of dental ceramics obtained in Germany, Spain and the UK were examined. Linear dose-response characteristics were obtained in the range <100 mGy to 10 Gy using thermoluminescence (TL), optically stimulated luminescence and infrared-stimulated luminescence measurement techniques. Measurements of time-resolved luminescence were also performed to examine the nature of the luminescence recombination under visible (470 nm) and IR (855 nm) stimulation. The results obtained by TL and optically stimulated techniques suggest that there may be deeper traps than previously observed in certain types of dental ceramic. Such traps may be less susceptible to optical and athermal fading than was reported in earlier studies. (author)

Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars

Energy Technology Data Exchange (ETDEWEB)

Pagonis, Vasilis, E-mail: vpagonis@mcdaniel.edu [McDaniel College, Physics Department, Westminster, MD 21157 (United States); Ankjærgaard, Christina [Soil Geography and Landscape Group & Netherlands Centre for Luminescence dating, Wageningen University, PO Box 47, 6700 AA Wageningen (Netherlands); Jain, Mayank [Center for Nuclear Technologies, Technical University of Denmark, DTU Risø Campus, Roskilde (Denmark); Chithambo, Makaiko L. [Department of Physics and Electronics, Rhodes University, PO BOX 94, Grahamstown 6140 (South Africa)

2016-09-15

Time-resolved infrared-stimulated luminescence (TR-IRSL) from feldspar samples is of importance in the field of luminescence dating, since it provides information on the luminescence mechanism in these materials. In this paper we present new analytical equations which can be used to analyze TR-IRSL signals, both during and after short infrared stimulation pulses. The equations are developed using a recently proposed kinetic model, which describes localized electronic recombination via tunneling between trapped electrons and recombination centers in luminescent materials. Recombination is assumed to take place from the excited state of the trapped electron to the nearest-neighbor center within a random distribution of luminescence recombination centers. Different possibilities are examined within the model, depending on the relative importance of electron de-excitation and recombination. The equations are applied to experimental TR-IRSL data of natural feldspars, and good agreement is found between experimental and modeling results.

Growth and luminescent properties of Yb3+--doped oxide single crystals for scintillator application

International Nuclear Information System (INIS)

Yoshikawa, A.; Ogino, H.; Shim, J.B.; Nikl, M.; Solovieva, N.; Fukuda, T.

2004-01-01

Rod-shaped (Lu 1-x Yb x ) 3 Al 5 O 12 with x=0.05, 0.15, 0.30 and (Y 1-x Yb x )AlO 3 with x=0.05, 0.10, 0.30 single crystals were grown by the micro-pulling-down method. Edge-defined film-fed growth method was used to prepare (Y 0.9 Yb 0.1 )VO 4 crystal, while Ca 8 (La 1.98 Yb 0.02 )(PO 4 ) 6 O 2 crystal was grown by the Czochralski method. Luminescence of these crystals was studied with main attention paid to the charge transfer emission of Yb 3+ . Temperature tuned decay times in the time scale of units--tens of nanosecond was measured as a feature possibly interesting for an application in scintillation detectors in positron emission tomography

Luminescence dating at Rose cottage cave: a progress report

CSIR Research Space (South Africa)

Woodborne, S

1997-10-01

Full Text Available Deal with infrared-stimulated luminescence and thermoluminescence dates from Rose Cottage Cave in South Africa. Discrepancy between luminescence and radiocarbon dates; Concentration of radioactive elements in sediments before and after leaching...

Luminescence basic concepts, applications and instrumentation

CERN Document Server

Virk, Hardev Singh

2014-01-01

The word luminescence was first used by a German physicist, Eilhardt Wiedemann, in 1888. He also classified luminescence into six kinds according to the method of excitation. No better basis of classification is available today. He recognized photoluminescence, thermoluminescence, electroluminescence, crystalloluminescence, triboluminescence, and chemiluminescence. The designations are obvious, characterized by the prefix. This Volume consists of 9 Chapters, including 8 Review Papers and one Case Study. The first two papers are based on OLEDs. Organic light emitting diodes (OLEDs) have been th

Defect-Induced Luminescence of a Self-Activated Borophosphate Phosphor

Science.gov (United States)

Han, Bing; Liu, Beibei; Dai, Yazhou; Zhang, Jie

2018-05-01

A self-activated borophosphate phosphor Ba3BPO7 was prepared via typical solid-state reaction in thermal-carbon reduction atmosphere. The structural and luminescence properties were investigated using x-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, and photoluminescence spectroscopy. Upon excitation with ultraviolet (UV) light, the as-prepared phosphor shows bright greenish-yellow emission with a microsecond-level fluorescence lifetime, which could result from the oxygen vacancies produced in the process of solid-state synthesis. The possible luminescence mechanism is proposed. Through the introduction of defects in the host, this work realizes visible luminescence in a pure borophosphate compound that does not contain any rare earth or transition metal activators, so it is helpful to develop defect-related luminescent materials in view of energy conservation and environmental protection for sustainable development.

Synthesis and luminescence enhancement of CaTiO{sub 3}:Bi{sup 3+} yellow phosphor by codoping Al{sup 3+}/B{sup 3+} ions

Energy Technology Data Exchange (ETDEWEB)

Cao, Renping, E-mail: jxcrp@163.com; Fu, Ting; Xu, Haidong; Luo, Wenjie; Peng, Dedong; Chen, Zhiquan; Fu, Jingwei

2016-07-25

CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors are synthesized by solid-state reaction method in air. With excitation 272 and 320 nm, broad PL band peaking at 555 nm with full width at half maximum ∼200 nm is observed in the range of 400–800 nm due to the {sup 3}P{sub 1,0} → {sup 1}S{sub 0} transitions of Bi{sup 3+} ion. PLE spectrum monitored at 555 nm contains two PLE band peaking at ∼272 and 320 nm within the range 230–420 nm owing to metal-to-metal charge-transfer and {sup 1}S{sub 0} → {sup 3}P{sub 1} transition of Bi{sup 3+} ion, respectively. The optimal Bi{sup 3+} doping concentration in CaTiO{sub 3}:Bi{sup 3+} phosphor is about 0.5 mol%. Luminescence properties of CaTiO{sub 3}:Bi{sup 3+} phosphor may be improved obviously by co-doping Al{sup 3+}/B{sup 3+} ions, and its emission intensity can be enhanced 13–15 times after Al{sup 3+} ion is co-doped. Luminous mechanism of CaTiO{sub 3}:Bi{sup 3+} phosphor is analyzed by energy level diagram of Bi{sup 3+} ion. Decay curve and time-resolved spectra confirm that only a single type of Bi{sup 3+} luminescence center exists in CaTiO{sub 3}:Bi{sup 3+} phosphor. - Graphical abstract: PL spectra of CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors and the corresponding pictures under 365 nm UV lamp. - Highlights: • CaTiO{sub 3}:Bi{sup 3+} and CaTiO{sub 3}:Bi{sup 3+}, Al{sup 3+}/B{sup 3+} phosphors are synthesized by solid-state reaction in air. • Broadband emission with FWHM ∼200 nm is observed within the range 400–800 nm. • Luminescence properties of CaTiO{sub 3}:Bi{sup 3+} phosphor can be improved by codoping Al{sup 3+}/B{sup 3+} ions. • PL intensity of CaTiO{sub 3}:Bi{sup 3+} phosphor can be enhanced 13–15 times after Al{sup 3+} ion is codoped.

Luminescent properties of terbium complex with phenylanthranilic acid

International Nuclear Information System (INIS)

Alakaeva, L.A.; Kalazhokova, I.A.; Naurzhanova, F.Kh.

1990-01-01

Existence of terbium luminescence reaction in complex with phenanthranilic acid (FAA) is ascertained. The optimal conditions of terbium complexing with FAA are found. The ratio of components in the complex is 1:1. The influence of foreign rare earth in terbium luminescence intensity in complex with FAA is studied

Doped luminescent materials and particle discrimination using same

Science.gov (United States)

Doty, F. Patrick; Allendorf, Mark D; Feng, Patrick L

2014-10-07

Doped luminescent materials are provided for converting excited triplet states to radiative hybrid states. The doped materials may be used to conduct pulse shape discrimination (PSD) using luminescence generated by harvested excited triplet states. The doped materials may also be used to detect particles using spectral shape discrimination (SSD).

Polarization memory of white luminescence of Ag nanoclusters dispersed in glass host.

Science.gov (United States)

Kuznetsov, A S; Tikhomirov, V K; Moshchalkov, V V

2012-09-10

A mechanism for white luminescence of Ag nanoclusters dispersed in oxyfluoride glass host has been revealed by studying a temperature dependence of its polarization memory. The spectral dependence of the polarization memory indicates the presence of a variety of Ag nanoclusters, particularly emitting in the blue, green and red. Temperature activated intercluster energy transfer has been found responsible for white luminescence. The means for increasing luminescence quantum yield have been suggested. This efficient white luminescence may be used in highly demanded devices, such as luminescent lamps, displays, color phosphors for LEDs, photovoltaic devices based on down shifting of solar spectrum.

Radiation induced coloring of glasses measured during and after electron irradiation

International Nuclear Information System (INIS)

Swyler, K.J.; Hardy, W.H. II; Levy, P.W.

1975-01-01

The growth of color centers during irradiation, and the decay after irradiation, were studied in two glasses using recently developed equipment for making optical absorption and luminescence measurements during and after electron irradiation. The glasses studied were NBS 710, a soda-lime silicate glass, and NBS 711, a lead silicate glass. Both glasses exhibit similar coloring characteristics. The radiation-induced absorption spectra consists of a weak gaussian shaped band in the visible, a stronger gaussian band in the ultraviolet, and a band edge ''shift'' which may be accurately approximated by a third gaussian band. For all absorption bands, the color center vs dose (or irradiation time) curves can be accurately resolved into two saturating exponential and one linear component. The decay curves obtained after the irradiation is terminated can be accurately expressed by three exponential components. Coloring and decay curves made at different dose rates indicate that the processes responsible for decay after irradiation and electron hole recombination during irradiation play important roles in determining the rate and extent of coloring. Results are qualitatively in agreement with some very simple kinetic treatments for color center formation. In some, but not all, respects the quantitative agreement is also good. Lastly, the results indicate that it is necessary to make measurements during irradiation to establish the formation kinetics of color centers that are unstable at the bombardment temperature. (U.S.)

Principal and secondary luminescence lifetime components in annealed natural quartz

International Nuclear Information System (INIS)

Chithambo, M.L.; Ogundare, F.O.; Feathers, J.

2008-01-01

Time-resolved luminescence spectra from quartz can be separated into components with distinct principal and secondary lifetimes depending on certain combinations of annealing and measurement temperature. The influence of annealing on properties of the lifetimes related to irradiation dose and temperature of measurement has been investigated in sedimentary quartz annealed at various temperatures up to 900 deg. C. Time-resolved luminescence for use in the analysis was pulse stimulated from samples at 470 nm between 20 and 200 deg. C. Luminescence lifetimes decrease with measurement temperature due to increasing thermal effect on the associated luminescence with an activation energy of thermal quenching equal to 0.68±0.01eV for the secondary lifetime but only qualitatively so for the principal lifetime component. Concerning the influence of annealing temperature, luminescence lifetimes measured at 20 deg. C are constant at about 33μs for annealing temperatures up to 600 0 C but decrease to about 29μs when the annealing temperature is increased to 900 deg. C. In addition, it was found that lifetime components in samples annealed at 800 deg. C are independent of radiation dose in the range 85-1340 Gy investigated. The dependence of lifetimes on both the annealing temperature and magnitude of radiation dose is described as being due to the increasing importance of a particular recombination centre in the luminescence emission process as a result of dynamic hole transfer between non-radiative and radiative luminescence centres

The interpretation of quartz optically stimulated luminescence equivalent dose versus time plots

International Nuclear Information System (INIS)

Bailey, R.M.

2000-01-01

Numerical modelling has shown that the form of the quartz OSL shine plateau (hereafter 'D e (t)-plot') is influenced by the effects of phototransferred TL in the ∼110 deg. C region. It is suggested also that the presence of multiple OSL components (as described by Partial bleaching and the decay form characteristics of quartz OSL. Radiat. Meas., 27, 123-136. The form of the optically stimulated luminescence signal of quartz: implications of dating. Unpublished PhD thesis, University of London) affects the form of the D e (t)-plot. Laboratory measurements of a fully reset and artificially dosed sample yielded non-flat D e (t)-plots, the deviation being greater for the larger of the two simulated palaeodoses, in accordance with theoretical predictions. It is suggested that the so-called 'shine plateau' test is of limited use in assessing the bleaching history of quartz sediments