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Sample records for stimulated luminescence properties

  1. Optically Stimulated Luminescence Properties Of Natural Schist

    NASA Astrophysics Data System (ADS)

    Stefanaki, E. C.; Afouxenidis, D.; Polymeris, G. S.; Sakalis, A.; Tsirliganis, N. C.; Kitis, G.

    Schist is a common siliciclastic geological material that has been extensively used in buildings as brick, tile and roofing slates. Its use, especially in the Mediterranean sea is widespread through the centuries. There are various examples from the ancient Greece, such as monuments from Knossos, Karthaia, as well as from modern Greece, such as traditional houses, etc. Schist is a metamorphic crystalline rock composed largely of silicon minerals, such as quartz, muscovite mica and feldspars. The type and composition of schists, as well as, the concentration of each mineral depends strongly on the type and the origin of the schist. Its past and modern use makes it a suitable candidate form archaeological dating, as well as, for retrospective dosimetry purposes. In the present work a preliminary characterization of schist is performed in order to investigate if some basic properties required for dating applications can be found in this material. The preliminary study concerns the optical stability, the sensitization and linearity of the Infrared Stimulated Luminescence (IRSL) resulting from feldspars, as well as the post IR Blue Optically Stimulated Luminescence (post - IR Blue OSL) resulting mostly from quartz. The results indicate that both signals are rapidly bleached when the sample is exposed to sunlight. The dose response was found to be linear for radiation doses at least up to 75 Gy for the IRSL signal and at least up to 25 Gy in the case of post - IR Blue OSL. The use of a single aliquot measurement protocol, due to the lack of sensitisation, extends the latter dose response linearity region up to 75 Gy for the post - IR Blue OSL signal of schist. Finally, the application of the double single-aliquot regenerative-dose protocol to schist was investigated, in order to recover,successfully, the equivalent dose in 4 - 11 μm grains of the compound.

  2. Thermoluminescence and optically stimulated luminescence properties of natural barytes.

    PubMed

    Kitis, G; Kiyak, N G; Polymeris, G S

    2010-12-01

    Heavy, baryte-loaded, concrete is commonly used as radiation shielding material around high energy particle accelerators. Concrete samples received from a shielding block located at CERN cite contain many crystalline inclusions which were identified as barytes by X-ray diffraction analysis and separated by their color, classified as white, orange and green. Basic properties of thermoluminescence (TL) and optically stimulated luminescence (OSL) signals of these barytes samples such as thermal and optical stability, repeatability and mainly the linearity of both their luminescence responses were investigated as a function of beta dose. These results are also discussed regarding detailed investigation on the correlation between TL and OSL signals and their implications for retrospective dosimetry. PMID:20620071

  3. On the photo and thermally stimulated luminescence properties of U doped SrBPO{sub 5}

    SciTech Connect

    Kumar, Mithlesh Mohapatra, M.; Natarajan, V.

    2014-12-15

    Highlights: • Synthesis of SrBPO{sub 5}:U phosphor by solid state route. • Confirmed the stabilization of uranium as UO{sub 2}{sup 2+}. • Evaluation of order of kinetics and trap parameters of the system. • ESR-TSL correlation of the observed glow peak. • Probable mechanism proposed for the TSL glow peak. - Abstract: Un-doped and uranium doped SrBPO{sub 5} samples were synthesized using solid-state reaction route and investigated for their photo and luminescence properties. Photoluminescence (PL) spectrum of uranium doped sample showed five peaks at 502, 524, 547, 569 and 597 nm. The average frequency of symmetric stretching of O=U=O in the ground electronic state was found to be about 757 cm{sup −1}. PL decay time measurements on the system confirmed the stabilization of uranium as UO{sub 2}{sup 2+} in the matrix. Thermally stimulated luminescence (TSL) measurements carried out on gamma irradiated SrBPO{sub 5}:U sample showed a glow peak at 390 °K, whose spectral characteristics was found to be typical of UO{sub 2}{sup 2+}. The trap parameters were evaluated using different heating rate method. Room temperature EPR data suggested the formation of borate and oxygen based radical centers in the gamma-irradiated sample. Detailed EPR-TSL correlation studies confirmed the destruction of the oxygen radical to be responsible for the observed glow peak.

  4. Orbital surveys of solar stimulated luminescence

    NASA Astrophysics Data System (ADS)

    Hemphill, W. R.; Theisen, A. F.; Tyson, R. M.; Granata, J. S.

    The Fraunhofer line discriminator (FLD) is an electro-optical device for imaging natural and manmade materials which have been stimulated to luminesce by the sun. An airborne FLD has been used to detect geochemically stressed vegetation, drought-stressed agricultural crops, industrial and residential pollution effluents, marine oil seeps, phosphate rock, uranium-bearing sandstone, and bioluminescent ocean plankton. Three-dimensional perspective plots of excitation and emission spectra, measured with a laboratory spectrometer, graphically depict similarities and differences in luminescence properties between sample materials. The laboratory data also include luminescence intensities at six Fraunhofer lines in the visible and near-infrared regions of the electromagnetic spectrum. Both the airborne and laboratory data suggest the feasibility of delineating and monitoring at least some of these luminescing materials from orbital altitude, such as a test flight aboard the Space Shuttle using an improved third-generation FLD.

  5. On optically stimulated luminescence properties of household salt as a retrospective dosemeter.

    PubMed

    Timar-Gabor, Alida; Trandafir, Oana

    2013-08-01

    Thermoluminescence (TL) and optically stimulated luminescence (OSL) in the UV (270-370 nm) spectral region have been investigated for five types of table salt (NaCl) available in Romanian supermarkets with a view to applying them in retrospective dosimetry. The salt samples gave bright TL signals with two main peaks at ∼100°C and at 300 or 260°C, depending on the origin of the salt and bright OSL signals under continuous stimulation with blue light. The OSL signal (stimulated at 100°C after a pre-heat of 10 s at 150°C) was used for investigations in a standard multiple aliquot procedure. The dose-response was found to be linear in the dose range investigated (up to ∼100 mGy) and the lower limit of detection for the samples varied from ∼0.01 to 14 mGy. These characteristics, along with the widespread abundance and low cost of household salt, confirm its potential as a retrospective dosemeter. PMID:23443414

  6. Luminescence properties and stimulated emission from Pr/sup 3 +/, Nd/sup 3 +/, and Er/sup 3 +/ ions in tetragonal lithium-lutecium fluoride

    SciTech Connect

    Kaminskii, A.A.; Markosyan, A.A.; Pelevin, A.V.; Polyakova, Y.A.; Sarkisov, S.E.

    1986-10-01

    This work continues an investigation of the scheelite-structure flourides by growing LiLuF/sub 4/ crystals containing Pr/sup 3 +/, Nd/sup 3 +/, Ho/sup 3 +/, and Er/sup 3 +/ ions by the Bridgman-Stockbarger method; the study of their absorption-luminescence properties and stimulated emission are also performed. Excitation of simulated emission in crystals 25 to 45 mm long and 6 mm in diameter with plane-parallel ends was accomplished by radiation from a pulsed xenon lamp. Continuous stimulated emission was also obtained at 300 K in LiLuF/sub 4//sup -/Nd/sup 3 +/ on pumping with radiation from an LNI tungsten lamp. Measurements of the orientational and intensity behavior for luminescence in the crystals indicates the possibility of their use for ultrashort stimulated emission pulses (nano- and pico-second duration) in the visible and near-IR at 300 K.

  7. Neutron dosimetry using optically stimulated luminescence

    NASA Astrophysics Data System (ADS)

    Miller, S. D.; Eschbach, P. A.

    1991-06-01

    The addition of thermoluminescent (TL) materials within hydrogenous matrices to detect neutron induced proton recoils for radiation dosimetry is a well known concept. Previous attempts to implement this technique have met with limited success, primarily due to the high temperatures required for TL readout and the low melting temperatures of hydrogen-rich plastics. Research in recent years PNL has produced a new Optically Stimulated Luminescence (OSL) technique known as the Cooled Optically Stimulated Luminescence (COSL) that offers, for the first time, the capability of performing extremely sensitive radiation dosimetry at low temperatures. In addition to its extreme sensitivity, the COSL technique offers multiple readout capability, limited fading in a one year period, and the capability of analyzing single grains within a hydrogenous matrix.

  8. Neutron dosimetry using optically stimulated luminescence

    SciTech Connect

    Miller, S.D.; Eschbach, P.A.

    1991-06-01

    The addition of thermoluminescent (TL) materials within hydrogenous matrices to detect neutron-induced proton recoils for radiation dosimetry is a well-known concept. Previous attempts to implement this technique have met with limited success, primarily due to the high temperatures required for TL readout and the low melting temperatures of hydrogen-rich plastics. Research in recent years at Pacific Northwest laboratories (PNL) has produced a new Optically Stimulated Luminescence (OSL) technique known as the Cooled Optically Stimulated Luminescence (COSL) that offers, for the first time, the capability of performing extremely sensitive radiation dosimetry at low temperatures. In addition to its extreme sensitivity, the COSL technique offers multiple readout capability, limited fading in a one-year period, and the capability of analyzing single grains within a hydrogenous matrix. 4 refs., 10 figs.

  9. Luminescent solar concentrator improvement by stimulated emission

    NASA Astrophysics Data System (ADS)

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W.; Schmidt, Timothy W.; Argyros, Alexander

    2015-12-01

    Luminescent solar concentrators (LSCs) offer the prospect of reducing the cost of solar energy, and are a promising candidate for building integrated photovoltaic (PV) structures. However, the realization of commercially viable efficiency of LSCs is currently hindered by reabsorption losses. In this work, a method is introduced for reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire length of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption, and directed by the seed laser towards a small target PV cell. A mathematical model of such a system is presented which identifies different physical parameters responsible for the power conversion efficiency and gives the net effective output power.

  10. Luminescent solar concentrators utilizing stimulated emission.

    PubMed

    Kaysir, Md Rejvi; Fleming, Simon; MacQueen, Rowan W; Schmidt, Timothy W; Argyros, Alexander

    2016-03-21

    Luminescent solar concentrators (LSCs) are an emerging technology that aims primarily to reduce the cost of solar energy, with great potential for building integrated photovoltaic (PV) structures. However, realizing LSCs with commercially viable efficiency is currently hindered by reabsorption losses. Here, we introduce an approach to reducing reabsorption as well as improving directional emission in LSCs by using stimulated emission. Light from a seed laser (potentially an inexpensive laser diode) passes through the entire area of the LSC panel, modifying the emission spectrum of excited dye molecules such that it is spectrally narrower, at wavelengths that minimize reabsorption to allow net gain in the system, and directed towards a small PV cell. A mathematical model, taking into account thermodynamic considerations, of such a system is presented which identifies key parameters and allows evaluation in terms of net effective output power. PMID:27136870

  11. Container Verification Using Optically Stimulated Luminescence

    SciTech Connect

    Tanner, Jennifer E.; Miller, Steven D.; Conrady, Matthew M.; Simmons, Kevin L.; Tinker, Michael R.

    2008-10-01

    Containment verification is a high priority for safeguards containment and surveillance. Nuclear material containers, safeguards equipment cabinets, camera housings, and detector cable conduit are all vulnerable to tampering. Even with a high security seal on a lid or door, custom-built hinges and interfaces, and special colors and types of finishes, the surfaces of enclosures can be tampered with and any penetrations repaired and covered over. With today’s technology, these repairs would not be detected during a simple visual inspection. Several suggested solutions have been to develop complicated networks of wires, fiber-optic cables, lasers or other sensors that line the inside of a container and alarm when the network is disturbed. This results in an active system with real time evidence of tampering but is probably not practical for most safeguards applications. A more practical solution would be to use a passive approach where an additional security feature was added to surfaces which would consist of a special coating or paint applied to the container or enclosure. One type of coating would incorporate optically stimulated luminescent (OSL) material. OSL materials are phosphors that luminesce in proportion to the ionizing radiation dose when stimulated with the appropriate optical wavelengths. The OSL fluoresces at a very specific wavelength when illuminated at another, very specific wavelength. The presence of the pre-irradiated OSL material in the coating is confirmed using a device that interrogates the surface of the enclosure using the appropriate optical wavelength and then reads the resulting luminescence. The presence of the OSL indicates that the integrity of the surface is intact. The coating itself could be transparent which would allow the appearance of the container to remain unchanged or the OSL material could be incorporated into certain paints or epoxies used on various types of containers. The coating could be applied during manufacturing

  12. Red persistent and photo-stimulated luminescence properties of SrCaSi5N8: Eu2+, Tm3+ solid solution

    NASA Astrophysics Data System (ADS)

    Wang, Jin; Zhang, Haoran; Lei, Bingfu; Dong, Hanwu; Zhang, Haiming; Liu, Yingliang; Lai, Nuolin; Fang, Yun; Chen, Zhijie

    2014-09-01

    The red persistent and photo-stimulated luminescent (PSL) nitride phosphor, SrCaSi5N8: Eu2+, Tm3+ solid solution, had been synthesized through conventional high temperature solid-state reaction. The SrCaSi5N8: Eu2+, Tm3+ phosphor shows strong photoluminescence (PL) and weak PSL (λem = 647 nm), both originating from the 4f65d-4f7 transition of Eu2+. Thermoluminescence (TL) glow curves measured at various stimulating conditions (UV excitation, in dark, laser stimulation after UV irradiation) show the same peak positions at 345 K and 360 K but great differences in the intensities. The afterglow decay curve presents excellent long-lasting red phosphorescence with a decay time of 30 min (⩾0.32 mcd/m2) after turning off the activating light. Moreover, the laser stimulated luminescence spectra, which feature sharp rising and falling edges (monitored at 647 nm) as the infrared laser diode (980 nm) excitation was turned on and off periodically, exhibit interesting rapidly responsive, erasable and rewritable abilities.

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

    NASA Astrophysics Data System (ADS)

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

    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.

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

    PubMed

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

    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. PMID:26606392

  15. An Optically Stimulated Luminescence Uranium Enrichment Monitor

    SciTech Connect

    Miller, Steven D.; Tanner, Jennifer E.; Simmons, Kevin L.; Conrady, Matthew M.; Benz, Jacob M.; Greenfield, Bryce A.

    2010-08-11

    The Pacific Northwest National Laboratory (PNNL) has pioneered the use of Optically Stimulated Luminescence (OSL) technology for use in personnel dosimetry and high dose radiation processing dosimetry. PNNL has developed and patented an alumina-based OSL dosimeter that is being used by the majority of medical X-ray and imaging technicians worldwide. PNNL has conceived of using OSL technology to passively measure the level of UF6 enrichment by attaching the prototype OSL monitor to pipes containing UF6 gas within an enrichment facility. The prototype OSL UF6 monitor utilizes a two-element approach with the first element open and unfiltered to measure both the low energy and high energy gammas from the UF6, while the second element utilizes a 3-mm thick tungsten filter to eliminate the low energy gammas and pass only the high energy gammas from the UF6. By placing a control monitor in the room away from the UF6 pipes and other ionizing radiation sources, the control readings can be subtracted from the UF6 pipe monitor measurements. The ratio of the shielded to the unshielded net measurements provides a means to estimate the level of uranium enrichment. PNNL has replaced the commercially available MicroStar alumina-based dosimeter elements with a composite of polyethylene plastic, high-Z glass powder, and BaFBr:Eu OSL phosphor powder at various concentrations. The high-Z glass was added in an attempt to raise the average “Z” of the composite dosimeter and increase the response. Additionally, since BaFBr:Eu OSL phosphor is optimally excited and emits light at different wavelengths compared to alumina, the commercially available MicroStar reader was modified for reading BaFBr:Eu in a parallel effort to increase reader sensitivity. PNNL will present the design and performance of our novel OSL uranium enrichment monitor based on a combination of laboratory and UF6 test loop measurements. PNNL will also report on the optimization effort to achieve the highest possible

  16. Luminescence properties of a Fibonacci photonic quasicrystal.

    PubMed

    Passias, V; Valappil, N V; Shi, Z; Deych, L; Lisyansky, A A; Menon, V M

    2009-04-13

    An active one-dimensional Fibonacci photonic quasi-crystal is realized via spin coating. Luminescence properties of an organic dye embedded in the quasi-crystal are studied experimentally and compared to theoretical simulations. The luminescence occurs via the pseudo-bandedge mode and follows the dispersion properties of the Fibonacci crystal. Time resolved luminescence measurement of the active structure shows faster spontaneous emission rate, indicating the effect of the large photon densities available at the bandedge due to the presence of critically localized states. The experimental results are in good agreement with the theoretical calculations for steady-state luminescence spectra. PMID:19365490

  17. Optically stimulated luminescence dosimetry with gypsum wallboard (drywall).

    PubMed

    Thompson, Jeroen W; Burdette, Kevin E; Inrig, Elizabeth L; Dewitt, Regina; Mistry, Rajesh; Rink, W Jack; Boreham, Douglas R

    2010-09-01

    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. PMID:20447939

  18. Determination of Landscape Diffusivity Using Optically Stimulated Luminescence and Infrared Stimulated Luminescence Techniques

    NASA Astrophysics Data System (ADS)

    Stang, D.; Rhodes, E. J.; Heimsath, A. M.

    2011-12-01

    As landscapes undergo surface lowering by weathering and erosion, soil formation, mixing and transport processes play a key role. Determining the rates of soil mixing and transport is key to developing reliable models of hillslope erosion and landscape development, and is important in establishing a value for landscape diffusivity in numerical simulations. Mixing processes include biological mechanisms such as grains moving by gravity within burrows or root holes, grains being transported upwards by burrowing animals such as moles, gophers, rabbits, spiders, ants and other organisms, or larger scale processes such as tree throw. Non-biological mechanisms include surface wash and other slope transport processes, frost heave, movement caused by wetting and drying cycles, and grain transport by water within sediment pores. As optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) signals are light sensitive, they are reset by daylight exposure each time quartz or feldspar grains are brought to the surface. After re-burial, signals slowly re-grow as the grains are exposed to environmental radiation. We have adopted two complementary approaches that can provide information on processes and rates of grain mixing. Firstly we measured the apparent age distribution of single grains of quartz from discrete depths, providing in-depth data on the full range of grain histories since their last surface encounter. Secondly, we measured contiguous 1 cm spits of sediment from monoliths (vertical columns of sediment approx. 10 x 10 cm) using bulk IRSL, dominated by emissions from feldspars. The second approach sums the signals from all feldspar grains, and provides a rapid method to identify features such as burrows and root holes, as well as rapidly deposited surface events (e.g. small debris flow lobes). Combining both approaches, we are able to quantify the magnitude and timing of macroscale mixing processes (e.g. burrows, sediment slugs), while also

  19. Monolithic Integrated Radiation Sensor Using Stimulated Luminescence From Alumina

    NASA Technical Reports Server (NTRS)

    McKeever, S. W. S.; Yukihara, E. G.; Stoebe, T. G.; Chen, T.-C.

    2005-01-01

    The project goal was to design and test a monolithic integrated device for radiation sensing, using optically stimulated luminescence (OSL) from Al2O3:C. The device would consist of GaN/InGaN-based components epitaxially grown on each side of a A12O3:C substrate. Radiation energy stored in the substrate would be stimulated by visible emission from a GaN light-emitting diode (LED) grown on one side of the device, and the OSL emission from the substrate (in the blue region of the spectrum) would be detected by the InGaN pi-n diode grown on the other side of the substrate. The primary application of the device would be in space radiation environments. Thus, two major research thrusts were launched during this project. Firstly, research at Oklahoma State University (Dr. Stephen W.S. McKeever and Dr. E.G. Yukihara) concentrated on characterization of the OSL properties of Al2O3:C in radiation fields typical of those experienced in low-Earth orbit. Secondly, research at the University of Washington (Co-Is, Dr. T.G. Stoebe and Dr. T. Chen) focused of device development and GaN/InGaN epitaxial growth. While progress in each line of research has been substantial, the ultimate goal (that of producing a working prototype device) has not yet been reached. We detail the research progress and identify outstanding issues in this paper.

  20. Optically stimulated luminescence signals of polymineral fine grains in the JSC Mars-1 soil simulant sample.

    PubMed

    Banerjee, D; Blair, M; Lepper, K; McKeever, S W S

    2002-01-01

    The results of various experiments which characterise the optically stimulated luminescence (OSL) signals from polymineral fine grains of a Martian soil simulant sample (JSC Mars-1) are presented. The blue-green stimulated luminescence signal has greater thermal stability than the infrared stimulated luminescence signal for pre-heat temperatures between 250 degrees C and 400 degrees C. Fading tests over a 2 month storage period at 20 degrees C indicate that in some aliquots of JSC Mars-1 both the blue-green stimulated luminescence and the infrared stimulated luminescence signals fade by as much as 50%, whereas in others there is no evidence of significant fading. Dose recovery experiments demonstrate that equivalent dose (measured/given) ratio varies from aliquot to aliquot, and the underestimation in dose is less than 5% for at least one aliquot, for both the infrared and blue-green stimulated luminescence signals. PMID:12382760

  1. Sedimentological processes in lahars: Insights from optically stimulated luminescence analysis

    NASA Astrophysics Data System (ADS)

    Muñoz-Salinas, Esperanza; Bishop, Paul; Zamorano, Jose-Juan; Sanderson, David

    2012-01-01

    A lahar is a sediment-laden flow capable of major destructive impacts on infrastructure and human life. How lahars transport sediment is thus a key issue for understanding lahar sedimentology and behavior, especially in terms of the lahar's hydraulic and rheological properties, which can be substantially altered as the lahar gains or loses material during its travel. In this research, we analyze lahar entrainment processes by evaluating luminescence signals (total photon counts) from lahar sediments using blue luminescence signals (BLSL). A portable OSL reader that analyzes several grams of polymineral and polygrain-size samples was applied. We use data from three lahars in the Tenenepanco and Huiloac gorges on Popocatépetl volcano (Mexico) to elucidate the ways in which lahars may gain, lose and transport sediment during flow. Sediment samples for luminescence analysis were taken through the full thickness of the lahar deposits at eight different sites for two lahars (1997 and 2001) and at one site for a lahar that occurred > 500 yrs ago. Mean luminescence values obtained for the 1997 lahar help to evaluate the relationship between the lahar entrainment processes and the drainage at the different sites. For the 2001 lahar this relationship was also established taking into account the channel slope. The main conclusion is that luminescence signals (total photon counts) can be used to detect entrained material in the flow because the bulked materials modify the final OSL signals. The application of this type of luminescence analysis thus has the potential to provide a better understanding of sediment entrainment in these sediment-laden flows.

  2. Luminescent properties of semiconductor photoelectrodes

    NASA Astrophysics Data System (ADS)

    Ellis, A. B.; Karas, B. R.

    1980-08-01

    The use of luminescent, n-type 5-1000-ppm CdS:Te and 10 ppm-CdS:Ag polycrystalline photoelectrodes as probes of recombination in photo-electrochemical cells is reported. Except for intensity, the emission spectra (lambda sub max, 600-700 nm) are insensitive to the presence of S2-/Sn2- electrolyte and to the excitation wavelengths and electrode potentials employed. With ultraband gap irradiation (lambda less than or = 500 nm) and aqueous S2-/Sn2- or Te2-/(Te2)2- electrolytes, optical energy is converted to electricity at 0.1-5% efficiency and to luminescence at 0.01-1.0% efficiency; the effects of surface preparation and grain boundaries in determining efficiency and discussed. Increasingly negative bias applied to CdS:Te and CdS:Ag photoanodes increases emission intensity by 15-100% while the photocurrent simultaneously declines to zero. Band gap edge 514.5-nm excitation yields smaller photocurrents and larger but much less potential dependent emission intensity. These results are consistent with the band bending model presently used to described photoelectrochemical phenomena.

  3. Fast neutron dosimeter using Cooled Optically Stimulated Luminescence (COSL)

    SciTech Connect

    Eschbach, P.A.; Miller, S.D.

    1991-10-01

    Data is presented that demonstrates the concept of a fast neutron dosimeter using Cooled Optically Stimulated Luminescence. CaF{sub 2}:Mn powder, compounded with polyethylene, was injection molded and pressed into 0.1-cm-thick sheets. The sheets were then cut to form dosimeters with dimensions, 1.25 cm by 1.25 cm. After a laser anneal, the dosimeters were exposed to various amounts (from 10 mSv to 100 mSv) of fast {sup 252}Cf neutrons. The exposed dosimeters were cooled to liquid nitrogen temperature, stimulated with laser light, and then allowed to warm up to room temperature whereupon the dose dependent luminescence was recorded with a photon counting system. When the control and gamma components were subtracted from the {sup 252}Cf response, a dose-dependent neutron response was observed. The design, construction, and preliminary performance of an automated system for the dose interrogation of individual CaF{sub 2}:Mn grains within the polyethylene matrix will also be discussed. The system uses a small CO{sub 2} laser to heat areas of the cooled dosimeter to room temperature. If the readout of very small grain within the plastic matrix is successful, it will enhance the neutron to gamma response of the dosimeter.

  4. Optically stimulated luminescence: Searching for new dosimetric materials

    NASA Astrophysics Data System (ADS)

    Yoshimura, E. M.; Yukihara, E. G.

    2006-09-01

    Optically stimulated luminescence (OSL) is increasingly being used as a dosimetric technique in various fields such as medical, environmental and space dosimetry, and sediment and archaeological dating. Nevertheless few compounds are suitable as OSL materials. In this work, a survey was made of various insulators, searching for candidates for new OSL dosimeters. Natural and synthetic crystals and glasses from numerous sources are included. Luminescence was stimulated with blue LEDs (470 nm) and with IR laser (830 nm) provided by an automatic reader. Irradiation was performed with a 90Sr/ 90Y beta source, and the emitted light was measured with a photomultiplier tube, protected with suitable optical filters. Thermoluminescence (TL) of the samples was also measured, with the same equipment, to evaluate the thermal and optical stability of the defects related to OSL and TL. Among the various investigated materials, Al 2O 3:Cr, Mg, Fe, MgAl 2O 4 spinels, Mg 2SiO 4:Tb, and natural fluorite show potential as OSL dosimeters. Some materials, as barium aluminoborate glasses, although showing intense OSL signals, present a high fading at room temperature. In that situation the OSL signal is related to low temperature TL peaks that also fade at room temperature. None of the investigated materials was specially prepared to be used as an OSL dosimeter, which means that work can be done, mainly in the impurity nature and content, in order to improve OSL signals and to overcome some of the shortcomings that were noticed.

  5. Luminescence properties of silicon-cellulose nanocomposite

    PubMed Central

    2012-01-01

    We have characterized the structure and luminescence properties for two-component material composed of nanocrystalline cellulose and nanocrystalline (less to 100 nm) silicon powder. An efficient and stable photoluminescence of nanocomposite, resistant to the influence of gas-phase oxidants, has been found. The obtained material has electret-like properties and demonstrates the possibility of multiple-recharging in an electric field near 5·103 V/cm at temperatures ranging from −70°C to 100°C. The presence of the electric field, as well as ozone or low-temperature plasma treatment, does not change the luminescence spectrum due to quantum size properties of silicon nanoparticles. We believe that these particles may appear in two states: both embedded in a cellulose matrix and in the form of mechanical mixture. PMID:22849811

  6. Luminescence properties of silicon-cellulose nanocomposite

    NASA Astrophysics Data System (ADS)

    Pikulev, Vitaly; Loginova, Svetlana; Gurtov, Valery

    2012-07-01

    We have characterized the structure and luminescence properties for two-component material composed of nanocrystalline cellulose and nanocrystalline (less to 100 nm) silicon powder. An efficient and stable photoluminescence of nanocomposite, resistant to the influence of gas-phase oxidants, has been found. The obtained material has electret-like properties and demonstrates the possibility of multiple-recharging in an electric field near 5·103 V/cm at temperatures ranging from -70°C to 100°C. The presence of the electric field, as well as ozone or low-temperature plasma treatment, does not change the luminescence spectrum due to quantum size properties of silicon nanoparticles. We believe that these particles may appear in two states: both embedded in a cellulose matrix and in the form of mechanical mixture.

  7. Identifying irradiated flours by photo-stimulated luminescence technique

    SciTech Connect

    Ramli, Ros Anita Ahmad; Yasir, Muhamad Samudi; Othman, Zainon; Abdullah, Wan Saffiey Wan

    2014-02-12

    Photo-stimulated luminescence (PSL) technique was used in this study to detect gamma irradiation treatment of five types of flours (corn, rice, tapioca, wheat and glutinous rice) at four different doses 0, 0.2, .05 and 1kGy. The signal level was compared with two threshold values (700 and 5000). With the exception of glutinous rice, all irradiated samples produced a strong signal above the upper threshold (5000 counts/60s). All control samples produced negative result with the signals below the lower threshold (700 counts/60s) suggesting that the samples have not been irradiated. Irradiated glutinous rice samples produced intermediate signals (700 - 5000 counts/60s) which were subsequently confirmed using calibrated PSL. The PSL signals remained stable after 90 days of storage. The findings of this study will be useful to facilitate control of food irradiation application in Malaysia.

  8. Identifying irradiated flours by photo-stimulated luminescence technique

    NASA Astrophysics Data System (ADS)

    Ramli, Ros Anita Ahmad; Yasir, Muhamad Samudi; Othman, Zainon; Abdullah, Wan Saffiey Wan

    2014-02-01

    Photo-stimulated luminescence (PSL) technique was used in this study to detect gamma irradiation treatment of five types of flours (corn, rice, tapioca, wheat and glutinous rice) at four different doses 0, 0.2, .05 and 1kGy. The signal level was compared with two threshold values (700 and 5000). With the exception of glutinous rice, all irradiated samples produced a strong signal above the upper threshold (5000 counts/60s). All control samples produced negative result with the signals below the lower threshold (700 counts/60s) suggesting that the samples have not been irradiated. Irradiated glutinous rice samples produced intermediate signals (700 - 5000 counts/60s) which were subsequently confirmed using calibrated PSL. The PSL signals remained stable after 90 days of storage. The findings of this study will be useful to facilitate control of food irradiation application in Malaysia.

  9. Protocols for Thermoluninescence and Optically Stimulated Luminescence Research at DOSAR

    SciTech Connect

    Bernal, SM

    2004-10-11

    The Life Sciences Division (LSD) of Oak Ridge National Laboratory (ORNL) has a long record of radiation dosimetry research at the Dosimetry Applications Research (DOSAR) facility complex. These facilities have been used by a broad segment of the research community to perform a variety of experiments in areas including, but not limited to, radiobiology, radiation dosimeter and instrumentation development and calibration, and materials testing in a variety of radiation environments. Collaborations with the University of Tennessee-Knoxville (UTK) have also led to important contributions in the area of archaeometry, particularly as it relates to the use of radiation dosimetry to date archaeological artifacts. This manual is to serve as the primary instruction and operation manual for dosimetric and archaeometric research at DOSAR involving thermoluminescence (TL) and optically stimulated luminescence (OSL). Its purpose is to (1) provide protocols for common practices associated with the research, (2) outline the relevant organizational structure, (3) identify the Quality Assurance plan, and (4) describe all the procedures, operations, and responsibilities for safe and proper operation of associated equipment. Each person who performs research at DOSAR using TL/OSL equipment is required to read the latest revision of this manual and be familiar with its contents, and to sign and date the manual's master copy indicating that the manual has been read and understood. The TL/OSL Experimenter is also required to sign the manual after each revision to signify that the changes are understood. Each individual is responsible for completely understanding the proper operation of the TL/OSL equipment used and for following the guidance contained within this manual. The instructions, protocols, and operating procedures in this manual do not replace, supersede, or alter the hazard mitigation controls identified in the Research Safety Summary (''Thermoluminescence/Optically Stimulated

  10. Optimized readout system for cooled optically stimulated luminescence

    NASA Astrophysics Data System (ADS)

    Miller, S. D.; Eschbach, P. A.

    1990-09-01

    Cooled Optically Stimulated Luminescence (COSL) in CaF2:Mn is an ionizing radiation dosimetry method recently developed at the Pacific Northwest Laboratory (PNL). In this method CaF2:Mn crystals irradiated by gamma radiation at room temperature are cooled to liquid nitrogen temperature (77 K), stimulated by ultraviolet laser light at 326 nm, and allowed to warm to room temperature. Light emission proportional to the gamma exposure occurs as the TLD warms from liquid nitrogen temperature to room temperature. The new method is an example of a highly sensitive phototransfer technique which could form the basis for future radiation dosimetry applications. Measurements to date have shown high potential for measuring gamma exposures in the range of 10 microR. The high sensitivity of the COSL technique is due in part to the larger quantum efficiency of radiative recombination at low temperatures and to the complete absence of the incandescent background associated with conventional thermoluminescent readout methods. Along with the potential for a system which is more sensitive than thermoluminescent readers, multiple COSL readouts can be performed with minimal reduction in the COSL intensity. The multiple readout capability can serve as a possible permanent dosimetry record, thus allowing the reanalysis of a questionable reading. In an attempt to optimize the sensitivity of the COSL method, a new readout system is being developed.

  11. Optically stimulated luminescence in doped NaF.

    PubMed

    Gaikwad, S U; Patil, R R; Kulkarni, M S; Bhatt, B C; Moharil, S V

    2016-05-01

    OSL in doped NaF is studied. Study shows that NaF:Mg,Cu,P phosphor possess good OSL properties having sensitivity comparable to that of commercially available Al2O3:C (Landauer Inc.). For the luminescence averaged over 3s the obtained OSL is 37% of that commercial available Al2O3:C. Of the several phosphors investigated, phosphor with impurities concentration Mg(0.01mol%), Cu(0.2mol%), P(1mol%) shows good OSL sensitivity good linearity in the 10mGy to 1Gy dose range and negligible fading. This sample shows a intense single TL peak around 350°C which gets depleted by 14% after the OSL readout. This imply that maximum OSL is coming from deep traps giving stability to the signal. The ease of preparation along with other good OSL properties will make this phosphor suitable for radiation dosimetry applications using OSL. PMID:26926379

  12. Pressure-Stimulated Synthesis and Luminescence Properties of Microcrystalline (Lu,Y)₃Al₅O₁₂:Ce³⁺ Garnet Phosphors.

    PubMed

    Atuchin, Victor V; Beisel, Nina F; Galashov, Eugeniy N; Mandrik, Egor M; Molokeev, Maxim S; Yelisseyev, Alexander P; Yusuf, Alexey A; Xia, Zhiguo

    2015-12-01

    The Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 phosphors were synthesized by solid state reaction at temperature 1623 K and pressure 1.5 × 10(7) Pa in (95% N2 + 5% H2) atmosphere. Under the conditions, the compounds crystallize in the form of isolated euhedral partly faceted microcrystals ∼19 μm in size. The crystal structures of the Lu2.98Ce0.01Y0.01Al5O12 and Y2.99Ce0.01Al5O12 garnets have been obtained by Rietveld analysis. The photoluminescence (PL) and X-ray excited luminescence (XL) spectra obtained at room temperature indicate broad asymmetric bands with maxima near 519 and 540 nm for Y2.99Ce0.01Al5O12 and Lu2.98Ce0.01Y0.01Al5O12, respectively. The light source was fabricated using the powder Lu2.98Ce0.01Y0.01Al5O12 phosphor and commercial blue-emitting n-UV LED chips (λ(ex) = 450 nm). It is found that the CIE chromaticity coordinates are (x = 0.388, y = 0.563) with the warm white light emission correlated color temperature (CCT) of 6400 K and good luminous efficiency of 110 lm/W. PMID:26544834

  13. Quantitative analysis of time-resolved infrared stimulated luminescence in feldspars

    NASA Astrophysics Data System (ADS)

    Pagonis, Vasilis; Ankjærgaard, Christina; Jain, Mayank; Chithambo, Makaiko L.

    2016-09-01

    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-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.

  14. A new method of retrospective radiation dosimetry: Optically stimulated luminescence in dental enamel

    SciTech Connect

    Godfrey-Smith, D.I.; Pass, B.

    1997-05-01

    Currently, retrospective biophysical radiation dosimetry lacks a technique that is sensitive, non-invasive, and portable. This has made reliable cause and effect relationships between radiation exposure and its outcomes in humans difficult to establish. Since optical technology is amenable to miniaturization, a search for optically stimulated luminescence in dental enamel was begun. The first successful detection of time dependent optically stimulated luminescence from {gamma} irradiated enamel was accomplished. This luminescence is absent in enamel that is not irradiated or that was heated following irradiation. Thermoluminescence observations were made concurrently with the optical measurements which clarified the role of the organic component of enamel. 20 refs., 5 figs.

  15. Conversion of the luminescence of laser dyes in opal matrices to stimulated emission

    SciTech Connect

    Alimov, O K; Basiev, T T; Orlovskii, Yu V; Osiko, V V; Samoilovich, M I

    2008-07-31

    The luminescence and laser characteristics of a synthetic opal matrix filled with organic dyes are studied upon excitation by nanosecond laser pulses. The appearance of stimulated emission in a partially ordered scattering medium is investigated. It is shown that if the luminescence spectrum of a dye (oxazine-17) is located far outside the photonic bandgap of the opal matrix, stimulated emission along a preferential direction in the (111) plane is observed when pumping exceeds a threshold even without an external optical cavity. The stimulated emission spectrum is considerably narrower than the luminescence spectrum and consists of several narrow lines located within the dye luminescence band. If the luminescence spectrum of a dye (rhodamine 6G) overlaps with the photonic bandgap of the opal matrix, a different picture is observed. The loss of radiation in the matrix leads to the red shift of the luminescence spectrum, while the stimulated emission as in the case of oxazine-17 lies is observed within the luminescence band. (active media, lasers, and amplifiers)

  16. Optically Stimulated Luminescence Response of Commercial SiO2 Optical Fiber

    SciTech Connect

    Bogard, James S; Espinosa Garcia, Guillermo

    2008-01-01

    The use of Optically Stimulated Luminescence (OSL) for radiation dosimetry has become increasingly popular in recent years. The OSL method is based on luminescence emitted from semiconductor materials stimulated with specific wavelengths of light, after being exposed to ionizing radiation. The OSL intensity is a function of the radiation dose absorbed by the material. This work complements previous studies by the authors of the thermoluminescence (TL) response by SiO{sub 2} commercial optical fiber exposed to ionizing radiation and provides preliminary results describing some of the material's OSL properties. Linear OSL response to beta-radiation dose, along with a consistent shape of the photon emission curve with time, were observed using a green/blue OSL excitation laser. The reproducibility of OSL response after repeated irradiations and the change in intensity with time were also examined. The search for and characterization of materials that exhibit this OSL response, in parallel with the continued development of OSL methodology and instrumentation, is an important scientific and commercial issue.

  17. Thermoluminescence and optically stimulated luminescence in various phases of doped Na2SO4

    NASA Astrophysics Data System (ADS)

    Gaikwad, S. U.; Patil, R. R.; Kulkarni, M. S.; Bhatt, B. C.; Moharil, S. V.

    2016-02-01

    The dependence of optically stimulated luminescence (OSL) and thermoluminescence (TL) response due to crystal phase in Cu and Cu,Mg-doped Na2SO4 was studied. Study shows that the slowly cooled samples which crystallize in phase V show good OSL sensitivity whereas the quenched samples of Na2SO4 which crystallize in phase III irrespective of doping show no OSL sensitivity. However, during storage when phase III samples get converted to phase V, samples show OSL sensitivity comparable to freshly prepared samples in phase V. Hence, it is observed that TL-OSL properties of doped Na2SO4 are phase dependent .This study will be helpful in developing OSL phosphors in which phase plays an important role in deciding the desired properties.

  18. Luminescent Cyclometalated Platinum and Palladium Complexes with Novel Photophysical Properties

    NASA Astrophysics Data System (ADS)

    Turner, Eric

    Organic light emitting diodes (OLEDs) is a rapidly emerging technology based on organic thin film semiconductors. Recently, there has been substantial investment in their use in displays. In less than a decade, OLEDs have grown from a promising academic curiosity into a multi-billion dollar global industry. At the heart of an OLED are emissive molecules that generate light in response to electrical stimulation. Ideal emitters are efficient, compatible with existing materials, long lived, and produce light predominantly at useful wavelengths. Developing an understanding of the photophysical processes that dictate the luminescent properties of emissive materials is vital to their continued development. Chapter 1 and Chapter 2 provide an introduction to the topics presented and the laboratory methods used to explore them. Chapter 3 discusses a series of tridentate platinum complexes. A synthetic method utilizing microwave irradiation was explored, as well as a study of the effects ligand structure had on the excited state properties. Results and techniques developed in this endeavor were used as a foundation for the work undertaken in later chapters. Chapter 4 introduces a series of tetradentate platinum complexes that share a phenoxy-pyridyl (popy) motif. The new molecular design improved efficiency through increased rigidity and modification of the excited state properties. This class of platinum complexes were markedly more efficient than those presented in Chapter 3, and devices employing a green emitting complex of the series achieved nearly 100% electron-to-photon conversion efficiency in an OLED device. Chapter 5 adapts the ligand structure developed in Chapter 4 to palladium. The resulting complexes exceed reported efficiencies of palladium complexes by an order of magnitude. This chapter also provides the first report of a palladium complex as an emitter in an OLED device. Chapter 6 discusses the continuation of development efforts to include carbazolyl

  19. Laboratory analysis and airborne detection of materials stimulated to luminesce by the sun

    USGS Publications Warehouse

    Hemphill, W.R.; Theisen, A.F.; Tyson, R.M.

    1984-01-01

    The Fraunhofer line discriminator (FLD) is an airborne electro-optical device used to image materials which have been stimulated to luminesce by the Sun. Such materials include uranium-bearing sandstone, sedimentary phosphate rock, marine oil seeps, and stressed vegetation. Prior to conducting an airborne survey, a fluorescence spectrometer may be used in the laboratory to determine the spectral region where samples of the target material exhibit maximum luminescence, and to select the optimum Fraunhofer line. ?? 1984.

  20. Structure and luminescence properties of tellurium(IV) complex compounds

    NASA Astrophysics Data System (ADS)

    Sedakova, T. V.; Mirochnik, A. G.; Karasev, V. E.

    2011-05-01

    Using the tellurium(IV) complex compounds as an example, we study the interrelation between the geometric structure and spectral luminescence properties. We find that, in the series of compounds of Te(IV), which are characterized by the island octahedral coordination of Te(IV) ions, the luminescence intensity depends on the degree of distortion of the Te(IV) coordination polyhedron, the Stokes shift, and the energy of the luminescence transition. We revealed that the considered series of Te(IV) compounds possess reversible thermochromic properties.

  1. Photostimulated luminescence properties of Eu2+ -doped barium aluminate phosphor.

    PubMed

    He, Quanlong; Qiu, Guangyu; Xu, Xuhui; Qiu, Jianbei; Yu, Xue

    2015-03-01

    An intense green photostimulated luminescence in BaAl2 O4 :Eu(2+) phosphor was prepared. The thermoluminescence results indicate that there are at least three types of traps (T1 , T2 , T3 ) with different trap depths in BaAl2 O4 :Eu(2+) phosphor according to the bands located at 327, 361 and 555 K, respectively, which are closely associated with the phosphor's long persistent luminescence and photostimulated luminescence properties. In addition, as a novel optical read-out form, a photostimulated persistent luminescence signal can be repeatedly obtained in BaAl2 O4 :Eu(2+) phosphor. This shows that re-trapping of the electron released from a deep trap plays an important role in photostimulated persistent luminescence. PMID:24954192

  2. MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry

    PubMed Central

    Oliveira, Luiz C.; Yukihara, Eduardo G.; Baffa, Oswaldo

    2016-01-01

    The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce3+ and Sm3+ emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy–30 Gy). The OSL associated with Ce3+ emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6–7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce3+, make this material also a strong candidate for 2D OSL dose mapping. PMID:27076349

  3. MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry

    NASA Astrophysics Data System (ADS)

    Oliveira, Luiz C.; Yukihara, Eduardo G.; Baffa, Oswaldo

    2016-04-01

    The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce3+ and Sm3+ emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy–30 Gy). The OSL associated with Ce3+ emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6–7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce3+, make this material also a strong candidate for 2D OSL dose mapping.

  4. MgO:Li,Ce,Sm as a high-sensitivity material for Optically Stimulated Luminescence dosimetry.

    PubMed

    Oliveira, Luiz C; Yukihara, Eduardo G; Baffa, Oswaldo

    2016-01-01

    The goal of this work was to investigate the relevant dosimetric and luminescent properties of MgO:Li3%,Ce0.03%,Sm0.03%, a newly-developed, high sensitivity Optically Stimulated Luminescence (OSL) material of low effective atomic number (Zeff = 10.8) and potential interest for medical and personal dosimetry. We characterized the thermoluminescence (TL), OSL, radioluminescence (RL), and OSL emission spectrum of this new material and carried out a preliminary investigation on the OSL signal stability. MgO:Li,Ce,Sm has a main TL peak at ~180 °C (at a heating rate of 5 °C/s) associated with Ce(3+) and Sm(3+) emission. The results indicate that the infrared (870 nm) stimulated OSL from MgO:Li,Ce,Sm has suitable properties for dosimetry, including high sensitivity to ionizing radiation (20 times that of Al2O3:C, under the measurement conditions) and wide dynamic range (7 μGy-30 Gy). The OSL associated with Ce(3+) emission is correlated with a dominant, practically isolated peak at 180 °C. Fading of ~15% was observed in the first hour, probably due to shallow traps, followed by subsequent fading of 6-7% over the next 35 days. These properties, together with the characteristically fast luminescence from Ce(3+), make this material also a strong candidate for 2D OSL dose mapping. PMID:27076349

  5. Luminescence and structural properties of oxyorthosilicate and Al2O3 nanophosphors

    SciTech Connect

    Blair, Michael W; Jacobsohn, Luiz G; Bennett, Bryan L; Tornga, Stephanie C; Muenchausen, Ross E; Yukihara, Eduardo G

    2008-01-01

    A large amount of research has been conducted on semiconducting quantum dots exploring quantum confinement effects. On the other hand, nanophosphors -- inorganic insulating nanostructured luminescent materials -- have received considerably less attention. Our research involving nanomaterials has then focused on the question: How does reduced dimensionality affect the physical and chemical behavior of nanophosphors? In order to partially answer this fundamental question, we have produced numerous oxides, among them Lu{sub 2}SiO{sub 5}Ce (LSO), Y{sub 2}SiO{sub 5}:Ce (YSO), Gd{sub 2}SiO{sub 5}:Ce (GSO), and Al{sub 2}O{sub 3}, and characterized their structural and luminescent properties. Structure, grain size, phase purity and chemical homogeneity in the nanoscale were determined using x-ray diffraction, transmission electron microscopy, and electron paramagnetic resonance. The luminescent properties of the nanophosphors were characterized by thermoluminescence, radioluminescence, photoluminescence, and optically stimulated luminescence. In this work, we present an overview of the nascent field of nanophosphors, and summarize the results obtained in our laboratory with particular emphasis on the luminescent properties.

  6. Remote auditing of radiotherapy facilities using optically stimulated luminescence dosimeters

    SciTech Connect

    Lye, Jessica Dunn, Leon; Kenny, John; Alves, Andrew; Lehmann, Joerg; Williams, Ivan; Kron, Tomas; Oliver, Chris; Butler, Duncan; Johnston, Peter; Franich, Rick

    2014-03-15

    Purpose: On 1 July 2012, the Australian Clinical Dosimetry Service (ACDS) released its Optically Stimulated Luminescent Dosimeter (OSLD) Level I audit, replacing the previous TLD based audit. The aim of this work is to present the results from this new service and the complete uncertainty analysis on which the audit tolerances are based. Methods: The audit release was preceded by a rigorous evaluation of the InLight® nanoDot OSLD system from Landauer (Landauer, Inc., Glenwood, IL). Energy dependence, signal fading from multiple irradiations, batch variation, reader variation, and dose response factors were identified and quantified for each individual OSLD. The detectors are mailed to the facility in small PMMA blocks, based on the design of the existing Radiological Physics Centre audit. Modeling and measurement were used to determine a factor that could convert the dose measured in the PMMA block, to dose in water for the facility's reference conditions. This factor is dependent on the beam spectrum. The TPR{sub 20,10} was used as the beam quality index to determine the specific block factor for a beam being audited. The audit tolerance was defined using a rigorous uncertainty calculation. The audit outcome is then determined using a scientifically based two tiered action level approach. Audit outcomes within two standard deviations were defined as Pass (Optimal Level), within three standard deviations as Pass (Action Level), and outside of three standard deviations the outcome is Fail (Out of Tolerance). Results: To-date the ACDS has audited 108 photon beams with TLD and 162 photon beams with OSLD. The TLD audit results had an average deviation from ACDS of 0.0% and a standard deviation of 1.8%. The OSLD audit results had an average deviation of −0.2% and a standard deviation of 1.4%. The relative combined standard uncertainty was calculated to be 1.3% (1σ). Pass (Optimal Level) was reduced to ≤2.6% (2σ), and Fail (Out of Tolerance) was reduced to >3

  7. Long persistent and optically stimulated luminescence behaviors of calcium aluminates with different trap filling processes

    SciTech Connect

    Zhang, Buhao; Xu, Xuhui; Li, Qianyue; Wu, Yumei; Qiu, Jianbei; Yu, Xue

    2014-09-15

    Properties of long persistent luminescence (LPL) and optically stimulated luminescence (OSL) of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} (R=Nd, Dy, Tm) materials were investigated. The observed phenomenon indicates that R{sup 3+} ions (R=Nd, Dy, Tm) have different effects on trap properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}. The greatly improved LPL performance was observed in Nd{sup 3+} co-doped samples, which indicates that the incorporation of Nd{sup 3+} creates suitable traps for LPL. While co-doping Tm{sup 3+} ions, the intensity of high temperature of thermoluminescence band in CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphors is enhanced for the formation of the most suitable traps which benefits the intense and stable OSL. These results suggest that the effective traps contributed to the LPL/OSL are complex, of which could be an aggregation formation with shallow and deep traps other than simple traps from co-doped R{sup 3+} ions. The mechanism presented in the end potentially provides explanations of why the OSL of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} exhibits different read-in/read-out performance as well. - Graphical abstract: OSL emission spectra of Ca{sub 0.995}Al{sub 2}O{sub 4}:0.0025Eu{sup 2+}, 0.0025R{sup 3+} (R=Nd, Dy, Tm) taken under varying stimulation time (0, 25, 50, 75, 100 s). Inset: Blue emission pictures under varying stimulation time. - Highlights: • The LPL and OSL properties of CaAl{sub 2}O{sub 4}:Eu{sup 2+}, R{sup 3+} were investigated. • An alternative approach to control the trap depth of CaAl{sub 2}O{sub 4}:Eu{sup 2+} phosphor was proposed. • A new oxide ETM phosphor exhibiting intense and stable OSL was explored.

  8. Detection of UV light based on chemically stimulated luminescence of crystal phosphors

    NASA Astrophysics Data System (ADS)

    Grankin, D. V.; Grankin, V. P.; Martysh, M. A.

    2016-06-01

    High-efficiency accommodation of heterogeneous-reaction energy via an electronic channel and the possibility of using this effect to design an ionizing (UV) radiation detector based on chemically stimulated luminescence have been investigated. Preliminary irradiation of a ZnS sample by UV light is found to cause a luminescence flash under subsequent exposure of the sample surface to a flux of hydrogen atoms. The flash intensity depends on the UV excitation level and increases by several orders of magnitude in comparison with an unirradiated sample. It is shown that a new method for detecting UV light using chemically stimulated luminescence of crystal phosphors accumulating light yield can be developed based on this effect.

  9. Polymorphic copper iodide clusters: insights into the mechanochromic luminescence properties.

    PubMed

    Benito, Quentin; Le Goff, Xavier F; Maron, Sébastien; Fargues, Alexandre; Garcia, Alain; Martineau, Charlotte; Taulelle, Francis; Kahlal, Samia; Gacoin, Thierry; Boilot, Jean-Pierre; Perruchas, Sandrine

    2014-08-13

    An in-depth study of mechanochromic and thermochromic luminescent copper iodide clusters exhibiting structural polymorphism is reported and gives new insights into the origin of the mechanochromic luminescence properties. The two different crystalline polymorphs exhibit distinct luminescence properties with one being green emissive and the other one being yellow emissive. Upon mechanical grinding, only one of the polymorphs exhibits great modification of its emission from green to yellow. Interestingly, the photophysical properties of the resulting partially amorphous crushed compound are closed to those of the other yellow polymorph. Comparative structural and optical analyses of the different phases including a solution of clusters permit us to establish a correlation between the Cu-Cu bond distances and the luminescence properties. In addition, the local structure of the [Cu4I4P4] cluster cores has been probed by (31)P and (65)Cu solid-state NMR analysis, which readily indicates that the grinding process modifies the phosphorus and copper atoms environments. The mechanochromic phenomenon is thus explained by the disruption of the crystal packing within intermolecular interactions inducing shortening of the Cu-Cu bond distances in the [Cu4I4] cluster core and eventually modification of the emissive state. These results definitely establish the role of cuprophilic interactions in the mechanochromism of copper iodide clusters. More generally, this study constitutes a step further into the understanding of the mechanism involved in the mechanochromic luminescent properties of metal-based compounds. PMID:25076411

  10. Persistent photoconductivity and optically stimulated luminescence in Zn0.8Mg0.2Se mixed crystals

    NASA Astrophysics Data System (ADS)

    Firszt, F.; McZyska, H.; Gowski, S.; Zakrzewski, J.; Strzakowski, K.; Wróbel, M.

    2004-03-01

    Photoelectric properties of Zn0.8Mg0.2Se mixed crystals grown by high pressure Bridgman method were investigated. Spectral distributions and temperature characteristics of photoconductivity as well as thermal and optical stimulation and quenching of luminescence and photoconductivity were measured. Relaxation of stored carriers were discussed in terms of random local potential fluctuation (RLPF) due to statistical fluctuations of composition. Based on the observed photoinduced phenomena in ZnxMg1-xSe, the potential applications of II-VI solid solutions for construction of optoelectronic devices were discussed.

  11. Dependence of the stimulated luminescence threshold in ZnO nanocrystals on their geometric shape

    SciTech Connect

    Gruzintsev, A. N. Redkin, A. N.; Barthou, C.

    2010-05-15

    The effect of the shape and dimensions of zinc oxide nanocrystals on the spontaneous luminescence decay times and the thresholds of stimulated luminescence in the ultraviolet spectral region is studied. It is shown that the columnar nanocrystals with hexagonal faceting exhibit the lowest threshold power of optical excitation for the diameters of the nanocavities are 100-200 nm, comparable to the absorption length for the excitation light. Different mechanisms of lasing are established for nanocrystals shaped as prisms and pyramids with a hexagonal base. Variations in the decay times and lasing thresholds can be attributed to different local densities of photon states in regularly shaped nanocrystals.

  12. Detection of surface impurity phases in high T.sub.C superconductors using thermally stimulated luminescence

    DOEpatents

    Cooke, D. Wayne; Jahan, Muhammad S.

    1989-01-01

    Detection of surface impurity phases in high-temperature superconducting materials. Thermally stimulated luminescence has been found to occur in insulating impurity phases which commonly exist in high-temperature superconducting materials. The present invention is sensitive to impurity phases occurring at a level of less than 1% with a probe depth of about 1 .mu.m which is the region of interest for many superconductivity applications. Spectroscopic and spatial resolution of the emitted light from a sample permits identification and location of the impurity species. Absence of luminescence, and thus of insulating phases, can be correlated with low values of rf surface resistance.

  13. Use of an airborne Fraunhofer line discriminator for the detection of solar stimulated luminescence

    USGS Publications Warehouse

    Watson, Robert D.; Hemphill, William R.

    1976-01-01

    Future work will include the integration of the FLO with a line scan imaging system in order to assess the contribution of two-dimensional spatial resolution to the interpretability and usefulness of luminescence data. It should also include 1) investigation of luminescence polarization of some materials, particularly metal stressed plants, 2) an assessment of the use of pulsed lasers to stimulate phosphorescence decay time in the nanosecond and microsecond ranges; and 3) a study to determine the feasibility of conducting an FLO experiment from the Space Shuttle or other spacecraft.

  14. Controlling electron trap depth to enhance optical properties of persistent luminescence nanoparticles for in vivo imaging.

    PubMed

    Maldiney, Thomas; Lecointre, Aurélie; Viana, Bruno; Bessière, Aurélie; Bessodes, Michel; Gourier, Didier; Richard, Cyrille; Scherman, Daniel

    2011-08-01

    Focusing on the use of nanophosphors for in vivo imaging and diagnosis applications, we used thermally stimulated luminescence (TSL) measurements to study the influence of trivalent lanthanide Ln(3+) (Ln = Dy, Pr, Ce, Nd) electron traps on the optical properties of Mn(2+)-doped diopside-based persistent luminescence nanoparticles. This work reveals that Pr(3+) is the most suitable Ln(3+) electron trap in the diopside lattice, providing optimal trap depth for room temperature afterglow and resulting in the most intense luminescence decay curve after X-ray irradiation. This luminescence dependency toward the electron trap is maintained through additional doping with Eu(2+), allowing UV-light excitation, critical for bioimaging applications in living animals. We finally identify a novel composition (CaMgSi(2)O(6):Eu(2+),Mn(2+),Pr(3+)) for in vivo imaging, displaying a strong near-infrared afterglow centered on 685 nm, and present evidence that intravenous injection of such persistent luminescence nanoparticles in mice allows not only improved but highly sensitive detection through living tissues. PMID:21702453

  15. Defect-related luminescent materials: synthesis, emission properties and applications.

    PubMed

    Zhang, Cuimiao; Lin, Jun

    2012-12-01

    Luminescent materials have found a wide variety of applications, including information displays, lighting, X-ray intensification and scintillation, and so on. Therefore, much effort has been devoted to exploring novel luminescent materials so far. In the past decade, defect-related luminescent materials have inspired intensive research efforts in their own right. This kind of luminescent material can be basically classified into silica-based materials, phosphate systems, metal oxides, BCNO phosphors, and carbon-based materials. These materials combine several favourable attributes of traditional commercially available phosphors, which are stable, efficient, and less toxic, being free of the burdens of intrinsic toxicity or elemental scarcity and the need for stringent, intricate, tedious, costly, or inefficient preparation steps. Defect-related luminescent materials can be produced inexpensively and on a large scale by many approaches, such as sol-gel process, hydro(solvo)thermal reaction, hydrolysis methods, and electrochemical methods. This review article highlights the recent advances in the chemical synthesis and luminescent properties of the defect-related materials, together with their control and tuning, and emission mechanisms (solid state physics). We also speculate on their future and discuss potential developments for their applications in lighting and biomedical fields. PMID:23019577

  16. Structural and luminescent properties of electron-irradiated silicon

    SciTech Connect

    Sobolev, N. A.; Loshachenko, A. S.; Aruev, P. N.; Kalyadin, A. E.; Shek, E. I.; Zabrodskiy, V. V.; Shtel'makh, K. F.; Vdovin, V. I.; Xiang, Luelue; Yang, Deren

    2014-02-21

    Structural defects induced by electron irradiation of p-Cz-Si wafers were identified. The influence of the annealing conditions in a chlorine-containing atmosphere on the structural and luminescent properties of the samples was examined. Light-emitting diodes based on electron-irradiated and high-temperature-annealed wafers were fabricated by a vapour-phase epitaxy technique and their luminescence properties were studied. A high-intensity dislocation-related D1 line was observed at 1.6 μm in the room-temperature electroluminescence spectrum.

  17. Luminescence and related properties of nanocrystalline porous silicon

    NASA Astrophysics Data System (ADS)

    Koshida, N.

    This document is part of subvolume C3 'Optical Properties' of volume 34 'Semiconductor quantum structures' of Landolt-Börnstein, Group III, Condensed Matter, on the optical properties of quantum structures based on group IV semiconductors. It discusses luminescence and related properties of nanocrystalline porous silicon. Topics include an overview of nanostructured silicon, its fabrication technology, and properties of nanocrystalline porous silicon such as confinement effects, photoluminescence, electroluminesce, carrier charging effects, ballistic transport and emission, and thermally induced acoustic emission.

  18. Synthesis and study of the luminescent properties of europium-doped yttrium niobate

    NASA Astrophysics Data System (ADS)

    Mester, A. Yu.; Mozharov, A. M.; Trofimov, A. N.; Zamoryanskaya, M. V.

    2016-05-01

    A method of synthesis of single-phase europium-doped yttrium niobate powders without using additional fluxes is developed. Using this method, a series of samples with different europium concentrations are synthesized. The phase composition, grain size, and luminescent properties of the synthesized powders are studied. The optimal dopant concentration corresponding to the maximum luminescence intensity is determined. It is shown that the decay time of the most intense luminescence line of europium decreases with increasing europium concentration. Comparative analysis of the luminescent properties of calcium tungstate and the luminescent properties of a synthesized sample with the highest luminescence intensity is performed.

  19. Luminescent properties of bismuth centres in aluminosilicate optical fibres

    SciTech Connect

    Bulatov, Lenar I; Mashinskii, Valerii M; Dvoirin, Vladislav V; Dianov, Evgenii M; Kustov, Evgenii F

    2010-02-28

    The shape and spectral position of the luminescence bands of bismuth-doped aluminosilicate glass fibres are shown to depend on excitation power and wavelength. This indicates that the red and IR luminescence bands are composed of several components. The absorption and radiative transitions involved are identified, and a diagram of energy levels and transitions is obtained for four modifications of a bismuth centre in different environments in the aluminosilicate glass network. The effect of local environment on the optical properties of the bismuth centres is examined. (optical fibres and waveguides)

  20. An affordable optically stimulated luminescent dosimeter reader utilizing multiple excitation wavelengths.

    PubMed

    Kearfott, Kimberlee J; West, W Geoffrey

    2015-10-01

    A lower-cost optically stimulated luminescence (OSL) reader with increased flexibility for pursuing laboratory research into OSL theory and application was designed and constructed. This was achieved by using off-the-shelf optical components and higher-power light emitting diodes. The resulting reader includes more wavelengths of excitation light than current commercial readers, as well as the ability to swap out filters and other components during an experiment. PMID:26142807

  1. Sensitivity to Stimulation, a Component of the Circadian Rhythm in Luminescence in Gonyaulax1

    PubMed Central

    Christianson, Roger; Sweeney, Beatrice M.

    1972-01-01

    A new method for the stimulation of bioluminescence in the dinoflagellate Gonyaulax polyedra is described. With this technique, in which cells flow through a capillary coil, it is possible to graduate the intensity of the stimulus by varying the flow rate. In continuous darkness, the threshold stimulus for cells in the middle of the day phase is greater than that for cells in the middle of the night phase. Some evidence suggests heterogeneity of sensitivity to stimulation among either cells or individual luminescent sources within a cell. At stimulus intensities much above threshold, the luminescence of both day- and night-phase cells is proportional to the number of cells within the capillary coil. Night-phase cells emit about 14 times as much light as do day-phase cells in continuous darkness. Single bioluminescent flashes from cells were recorded with a high speed camera. No significant difference in flash kinetics was found between cells in the day and the night phase in continuous darkness. Cells in the night phase emit a flash three to five times brighter than that from day-phase cells. About twice as many flashes are recorded in a given time from a population of night-phase cells. The activity of both luciferin and luciferase have been shown to vary rhythmically. The differences in threshold and number of flahses are evidence for a second component of the circadian rhythm in luminescence, a rhythm in sensitivity to stimulation. PMID:16658099

  2. Luminescence properties of lustre decorated majolica

    NASA Astrophysics Data System (ADS)

    Galli, A.; Martini, M.; Sibilia, E.; Padeletti, G.; Fermo, P.

    Luminescence measurements have been performed on several Italian Renaissance ceramic shards produced in central Italy, as well as on some others from Hispano-Moresque and Fatimid periods. The aim of this study was the characterisation of the raw materials used to manufacture lustre decorated majolica. At first, the thermoluminescence (TL) dating of all ceramic bodies was performed, because the shards lacked sure chronological attribution, having been provided by private collectors, or found during emergency restoration works or archaeological surveys. To characterise the defects and the recombination centers of the different components of the ceramics (ceramic body, glaze, glaze, and lustre), radioluminescence (RL) measurements have been performed on samples representative of each historical period. The dating results are reported, as well as the preliminary RL results.

  3. Optically stimulated luminescence in K2SO4:AEu (A=Ca,Na,Al)

    NASA Astrophysics Data System (ADS)

    More, Y. K.; Patil, R. R.; Wankhede, S. P.; Kulkarni, M. S.; Kumar, Munish; Bhatt, B. C.; Moharil, S. V.

    2015-08-01

    Optically stimulated luminescence in doped K2SO4 is reported. K2SO4 was prepared by simple melt quenched process using readymade potassium sulphate. Samples were doped with Eu and AEu (A=Ca, Na and Al). Out of these samples K2SO4:Eu and K2SO4:Ca,Eu shows good OSL response to 470 nm optical stimulation. K2SO4:Eu and K2SO4:Ca,Eu have the sensitivities comparable with that of commercial phosphor Al2O3:C (Landauer).

  4. Investigation of a BeO-based optically stimulated luminescence dosemeter.

    PubMed

    Sommer, M; Henniger, J

    2006-01-01

    The optical sensitivity of BeO-based luminophors has been well-known for many years. The optical stimulation of BeO with blue light is most effective. Then the dosemeters emit luminescent light in the ultraviolet-range around 325 nm. Matched on these facts a simple optically stimulated luminescence (OSL) treatment has been developed. Intense blue light-emitting diodes are used for cw-stimulation. A Hamamatsu solar blind photomultiplier detects the OSL-light. Good separation of both spectral ranges by optical filters is very important. The dosemeter has a linear dose response between approximately 20 muGy and >10 Gy. It was suggested, that a modification of stimulation conditions would allow measurements down to 1 muGy. Fading, photon energy dependence and reproducibility of OSL-signal correspond well with requirements to clinical and personal dosemeters. In addition, basic questions of the OSL-process in BeO have been investigated. A relevant point of interest was the dependency of the OSL-signal on stimulation power. PMID:16735572

  5. Photoelectric and luminescent properties of dysprosium-doped silver chloride

    SciTech Connect

    Novikov, G. F. Rabenok, E. V.; Bocharov, K. V.; Lichkova, N. V.; Ovchinnikov, O. V.; Latyshev, A. N.

    2011-02-15

    The influence of dysprosium doping on the photoelectric and luminescent properties of AgCl crystals is studied by methods of microwave photoconductivity and photoluminescence. Doping affects both the loss kinetics of photogenerated electrons and luminescence spectra and parameters of photostimulated burst of luminescence. It is shown that the charged [Dy{sub Ag}{sup {center_dot}{center_dot}} {center_dot} V Prime {sub Ag}]{sup {center_dot}} or neutral [Dy{sub Ag}{sup {center_dot}{center_dot}} {center_dot} 2V Prime {sub Ag}]{sup x} complexes are responsible for a new luminescence band peaked at 470 nm, which manifests itself at weight concentrations of the doping additive >10{sup -6}%. The long-wavelength shoulder at 570 nm in the photoluminescence spectra is attributed to intracenter transitions in the Dy{sup 3+} ions. The rate constant of the reaction of electron capture into the traps forming upon introduction of the dopant, k{sub t} = (3-5) Multiplication-Sign 10{sup -8} cm{sup 3} s{sup -1}, is evaluated. It is assumed that the traps are Dy{sup 3+} dysprosium ions.

  6. Optically stimulated luminescence in doped NaCl

    NASA Astrophysics Data System (ADS)

    Gaikwad, S. U.; Patil, R. R.; Kulkarni, M. S.; Bhatt, B. C.; Moharil, S. V.

    2016-05-01

    NaCl:Ca,Cu,P NaCl:Mg,Cu,P OSL phosphors are synthesized. Intense OSL is observed in these samples which is 14 times more than Al2O3:C. Same samples coated with PVA (poly vinyl actetae) polymer also show similar OSL properties and these coated samples are found to be less susceptible to the moisture due to protected layer of hydrophobic polymer. These coated samples may be useful as OSL dosimetersdue to high sensitivity and less or no susceptibility to moisture.

  7. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    SciTech Connect

    Song, Xue-Qin Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-15

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis([(2′-furfurylaminoformyl)phenoxyl]methyl)-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 6{sup 3}, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of Eu{sup III}, Tb{sup III} and Dy{sup III} complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in Eu{sup III}, Tb{sup III} and Dy{sup III} complexes can be efficiently sensitized by the ligand. - Graphical abstract: We present herein six lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display diverse structures but also possess strong luminescence properties. - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit diverse structures. • The luminescent properties of Tb{sup III}, Eu{sup III} and Dy{sup III} complexes are discussed in detail.

  8. The persistent luminescence and up conversion photostimulated luminescence properties of nondoped Mg2SnO4 material

    NASA Astrophysics Data System (ADS)

    Zhang, Jiachi; Yu, Minghui; Qin, Qingsong; Zhou, Hongliang; Zhou, Meijiao; Xu, Xuhui; Wang, Yuhua

    2010-12-01

    The nondoped Mg2SnO4 material with inverse spinel structure was synthesized by solid state reaction. This phosphor showed a broad green emission band covering 470-550 nm under 291 nm excitation, which was due to the recombination of F centers with holes. Stimulated by 980 nm infrared laser, the green photostimulated luminescence was first observed in a nondoped oxide. After ultraviolet irradiation, the green persistent luminescence of Mg2SnO4 could be seen in darkness for about 5 h. The decay curves revealed that the long persistent luminescence was governed by tunneling mechanism and it proved the presence of different trap clusters in Mg2SnO4. These trap clusters (such as [SnMg••-Oi″], [SnMg••-2e'], and [SnMg••-e″]) induced the trap levels with different depths in band gap and corresponded to the three components (at 110, 168, and 213 °C) of the thermoluminescence glow curve of Mg2SnO4. These trap levels with different depths were proved to be not independent. It revealed that the shallow traps (110 °C) and part of the deep traps (168 and 213 °C) were involved in the persistent luminescence. Meanwhile, all the shallow and deep traps were responsible for the photostimulated luminescence. Accordingly, the photoluminescence, persistent, and photostimulated luminescence mechanisms of the nondoped Mg2SnO4 material were first proposed.

  9. Pulsed Photon-Stimulated Luminescence (PPSL) as a tool in retrospective dosimetry.

    PubMed

    Niedermayer, M; Bayer, A

    2010-06-01

    The analysis of luminescence of minerals extracted from pottery and bricks is a well-known tool in retrospective dosimetry. In the past, the detection limit of this method has been reported to lie in general in the order of magnitude of about 10 mGy. For most applications in accidental dosimetry, this is more than sufficient. Still there are some applications, such as the determination of the natural dose if the samples are comparatively young and the doses involved are small (e.g. in epidemiological studies), where the possibility of determining much smaller doses is desirable. As the detection limit is often defined by the measurement background, in this study the application of the 'SURRC Pulsed Photostimulated Luminescence (PPSL) Irradiated Food Screening System (SURRC PPSL Irradiated Food Screening System)', where the measurement background is suppressed in a very innovative way, was tested for dosimetric purposes. Therefore, the luminescence parameters were determined for a set of nine samples of modern bricks. It was found that depending on individual samples, it was possible to determine values as small as a few 100 microGy. Herewith a new application for the 'SURRC PPSL Irradiated Food Screening System' presented itself and further applications in dose reconstruction became available. As to the dosimetric properties of the sample material, it was found that although all the samples were from different brickmakers and places throughout Germany, surprisingly the luminescence parameters were similar, so that it was possible to define a generalised measurement sequence. An interpretation is given. PMID:20085899

  10. Charge trapping induced by plasma in alumina electrode surface investigated by thermoluminescence and optically stimulated luminescence

    SciTech Connect

    Ambrico, P. F.; Ambrico, M.; Schiavulli, L.; Ligonzo, T.; Augelli, V.

    2009-02-02

    The plasma of a dielectric barrier discharge can fill traps in the alumina that cover the electrode. Trap energies and lifetimes are estimated by thermoluminescence and optically stimulated luminescence. Comparison with similar results for traps created by other radiation sources clarifies the mechanisms regulating this effect. Alumina's trap energies are approximately 1 eV, and the traps remain active for several days after plasma exposure. These results could be important to keep dielectric barrier discharge plasmas uniform since a trapped charge can be an electron reservoir.

  11. Optically stimulated luminescence in NaMgF{sub 3}:Eu{sup 2+}

    SciTech Connect

    Dotzler, C.; Williams, G. V. M.; Rieser, U.; Edgar, A.

    2007-09-17

    Optically stimulated luminescence (OSL) and thermoluminescence (TL) measurements were performed on polycrystalline NaMgF{sub 3}:Eu{sup 2+} as well as sintered and quenched NaMgF{sub 3}:Eu{sup 2+} after exposure to ionizing radiation. The authors find a range of TL traps and the sintering and quenching process reduces the concentration of shallow traps. The resultant time integrated OSL intensity is linear from microgray dose levels to approximately 100 Gy, and hence this material is suitable for a personal and environmental dosimetry, where low dose levels are encountered and high sensitivity is required.

  12. Stimulation of luminescence of mycelium of luminous fungus Neonothopanus nambi by ionizing radiation.

    PubMed

    Kobzeva, Tatiana V; Melnikov, Anatoly R; Karogodina, Tatiana Y; Zikirin, Samat B; Stass, Dmitri V; Molin, Yuri N; Rodicheva, Emma K; Medvedeva, Svetlana E; Puzyr, Alexey P; Burov, Andrey A; Bondar, Vladimir S; Gitelson, Joseph I

    2014-11-01

    The luminescent system of higher luminous fungi is not fully understood and the enzyme/substrate pair of the light emission reaction has not been isolated. It was suggested that luminescence of fungi involves oxidase-type enzymes, and reactive oxygen species are important for fungal light production. Generation of reactive oxygen species can be stimulated by ionizing irradiation, which has not been studied for luminous fungi. We report the effect of X-irradiation on the luminescence of fungus Neonothopanus nambi. Experiments were performed with mycelium on a home-built setup based on an X-ray tube and monochromator/photomultiplier tube. Application of X-rays does not change the emission spectrum, but after approximately 20 min of continuous irradiation, light production from unsupported mycelium starts growing and increases up to approximately five times. After peaking, its level decreases irrespective of the presence of X-irradiation. After staying at a certain level, light production collapses to zero, which is not related to the drying of the mycelium or thermal impact of radiation. The observed shape of kinetics is characteristic of a multistage and/or chain reaction. The time profile of light production must reflect the current levels of radicals present in the system and/or the activity of enzyme complexes involved in light production. PMID:24729569

  13. Constraining the age and formation of stone runs in the Falkland Islands using Optically Stimulated Luminescence

    NASA Astrophysics Data System (ADS)

    Hansom, James D.; Evans, David J. A.; Sanderson, David C. W.; Bingham, Robert G.; Bentley, Michael J.

    2008-02-01

    The stone runs of the Falkland Islands are thought to be periglacial blockfields but their age and detailed origin remain enigmatic. We examine the fine sediments that underlie two stone runs in order to establish whether Optically Stimulated Luminescence (OSL) dating is an appropriate technique to constrain the date of emplacement of the fine sediments and, hence, the stone runs. Six samples were collected from two accessible sections during the Scotia Centenary Antarctic expedition in 2003. All samples were used to explore the main luminescence characteristics of the sediment, followed by quartz SAR dating procedures on four of the samples. Age estimates range from in excess of 54 ka to 16 ka, suggesting that the overlying stone runs remained active until 16 ka or later. Saturation of luminescence from quartz limits age estimates for the oldest samples in the sequences, however these are not critical to define the upper limit to the emplacement age for the overlying stone runs. The sediments also contain feldspars and initial results suggest that these may be useful in extending the timescale further, but require further samples to be obtained from other parts of the sequence. Extending the method to other stone runs in the Port Stanley Formation may allow estimates of the age of stabilisation of the stone runs to be extended into the 1-250 ka timescale. Luminescence dating of the underlying sediments, used in conjunction with cosmogenic isotope dating of the surface boulders from a range of locations along the stone runs, appears to offer a useful route towards decoding the depositional history of these impressive deposits.

  14. Constraining Paleo-Glacier Dynamics Using Optically Stimulated Luminescence (OSL) Bedrock Exposure Dating

    NASA Astrophysics Data System (ADS)

    Brun, F.; Valla, P.; King, G. E.; Herman, F.

    2014-12-01

    Quantifying glacier dynamics over the late-Pleistocene remains an important challenge for understanding glacial response to climate change. Historical glacier reconstructions are spatially limited (e.g. the European Alps) and cover only the last ~100 yrs, restricting their use as paleoclimatic proxies. Bedrock dating methods such as Terrestrial Cosmogenic Nuclides (TCN) dating or lichenometry allows glacier fluctuations to be reconstructed over longer timescales. However, these methods have limited temporal resolution, and therefore do not enable accurate dating of recent glacier fluctuations (e.g. short glacier re-advances). Here, we use a novel in situ dating method based on Optically Stimulated Luminescence (OSL) to fill this temporal/spatial gap. OSL dating is based on the time-accumulation of trapped electrons in the lattice defects of minerals. OSL-exposure dating is based on the bleaching (i.e. resetting) of the minerals' luminescence signal when they are exposed to light (Sohbati et al., 2012 JGR-Solid Earth), which depends on exposure time, effective photon flux and light attenuation by minerals. We analyzed 10 samples in the Val d'Hérens (Swiss Alps) where post-LGM glacier dynamics remain poorly constrained and short glacier re-advances are thought to occur during the Holocene. Bedrock samples were drilled and small cores were sliced into 1-mm thick discs from which natural luminescence profiles were measured. We calibrated the luminescence model parameters using historically-exposed bedrock samples (~100 yr) near the Mont-Miné glacier, and used this on-site calibration to date surface exposure of glacial bedrock at various elevations along the valley; initial relative dating results are promising. Although OSL-exposure dating appears an efficient tool for historical glacier reconstructions, OSL bleaching over longer timescales (i.e. late-Pleistocene to Holocene) requires more investigation before use as a chronometer.

  15. Changes in optically stimulated luminescent dosimeter (OSLD) dosimetric characteristics with accumulated dose

    SciTech Connect

    Jursinic, Paul A.

    2010-01-15

    Purpose: A new type of in vivo dosimeter, an optically stimulated luminescent dosimeter (OSLD), has now become commercially available for clinical use. The OSLD is a plastic disk infused with aluminum oxide doped with carbon (Al{sub 2}O{sub 3}:C). Crystals of Al{sub 2}O{sub 3}:C, when exposed to ionizing radiation, store energy that is released as luminescence (420 nm) when the OSLD is illuminated with stimulation light (540 nm). The intensity of the luminescence depends on the dose absorbed by the OSLD and the intensity of the stimulation light. The effects of accumulated dose on OSLD response were investigated. Methods: The OSLDs used in this work were nanodot dosimeters, which were read with a MicroStar reader (Landauer, Inc., Glenwood, IL). Dose to the OSLDs was delivered by 6 MV x rays and gamma rays from Co-60 and Ir-192. The signal on the OSLDs after irradiation is removed by optical annealing with a 150 W tungsten-halogen lamp or a 14 W compact fluorescent lamp was investigated. Results: It was found that OSLD response to dose was supralinear and this response was altered with the amount of accumulated dose to the OSLD. The OSLD response can be modeled by a quadratic and an exponential equation. For accumulated doses up to 60 Gy, the OSLD sensitivity (counts/dose) decreases and the extent of supralinear increases. Above 60 Gy of accumulated dose the sensitivity increases and the extent of supralinearity decreases or reaches a plateau, depending on how the OSLDs were optically annealed. With preirradiation of OSLDs with greater than 1 kGy, it is found that the sensitivity reaches a plateau 2.5 folds greater than that of an OSLD with no accumulated dose and the supralinearity disappears. A regeneration of the luminescence signal in the dark after full optical annealing occurs with a half time of about two days. The extent of this regeneration signal depends on the amount of accumulated dose. Conclusions: For in vivo dosimetric measurements, a precision of

  16. Luminescent and thermochromic properties of tellurium(IV) halide complexes with cesium

    NASA Astrophysics Data System (ADS)

    Sedakova, T. V.; Mirochnik, A. G.

    2016-02-01

    The spectral-luminescent and thermochromic properties of complex compounds of the composition Cs2TeHal6 (Hal = Cl, Br, I) are studied. The interrelation between the geometric structure and spectral-luminescent properties is studied using the example on complex compounds of tellurium(IV) halides with cesium. The Stokes shift and the luminescence intensity of Te(IV) ions with island octahedral coordination are found to depend on the position of the A band in the luminescence excitation spectra, the diffuse reflection, and the energy of the luminescent 3 P 1 → 1 S 0 transition of the tellurium(IV) ion. The maximum luminescence intensity and the minimum Stokes shift at 77 and 300 K are observed for Cs2TeCl6. The geometrical and electronic factors responsible for luminescence intensification in Te(IV) complexes under study are analyzed.

  17. Analytical modeling of relative luminescence efficiency of Al2O3:C optically stimulated luminescence detectors exposed to high-energy heavy charged particles.

    PubMed

    Sawakuchi, Gabriel O; Yukihara, Eduardo G

    2012-01-21

    The objective of this work is to test analytical models to calculate the luminescence efficiency of Al(2)O(3):C optically stimulated luminescence detectors (OSLDs) exposed to heavy charged particles with energies relevant to space dosimetry and particle therapy. We used the track structure model to obtain an analytical expression for the relative luminescence efficiency based on the average radial dose distribution produced by the heavy charged particle. We compared the relative luminescence efficiency calculated using seven different radial dose distribution models, including a modified model introduced in this work, with experimental data. The results obtained using the modified radial dose distribution function agreed within 20% with experimental data from Al(2)O(3):C OSLDs relative luminescence efficiency for particles with atomic number ranging from 1 to 54 and linear energy transfer in water from 0.2 up to 1368 keV µm(-1). In spite of the significant improvement over other radial dose distribution models, understanding of the underlying physical processes associated with these radial dose distribution models remain elusive and may represent a limitation of the track structure model. PMID:22173080

  18. Mesomorphic and luminescent properties of disubstituted polyacetylenes bearing biphenyl pendants

    NASA Astrophysics Data System (ADS)

    Lam, Jacky W. Y.; Law, Chi Kong; Dong, Yuping; Wang, Jiannong; Ge, Weikun; Tang, Ben Zhong

    2003-01-01

    Liquid crystalline and light emitting properties of two new disubstituted polyacetylenes bearing biphenyl pendants (-{(R)CC[(CH 2) 4OCO-Biph-OC 7H 15]} n-, RCH 3 ( 1), C 6H 5 ( 2), Biph=4,4 '-biphenylyl) were investigated. Whereas 1 formed enantiotropic nematic phase, 2 was non-mesomorphic. Upon photoexcitation, the THF solutions of 1 and 2 emitted strong UV and blue light of 369 and 460 nm, respectively, whose quantum efficiencies were higher than that of poly(1-phenyl-1-octyne), a highly luminescent disubstituted polyacetylene.

  19. Deep levels in high resistivity GaN detected by thermally stimulated luminescence and first-principles calculations

    NASA Astrophysics Data System (ADS)

    Gai, Yanqin; Li, Jingbo; Hou, Qifeng; Wang, Xiaoliang; Xiao, Hongling; Wang, Cuimei; Li, Jinmin

    2009-08-01

    Thermally stimulated luminescence spectroscopy has been applied to study the deep centres in unintentionally doped high resistivity GaN epilayers grown by the metal organic chemical vapour deposition method on c-sapphire substrates. Two trap states with activation energies of 0.12 and 0.62 eV are evaluated from two luminescence peaks at 141.9 and 294.7 K in the luminescence curve. Our spectroscopy measurement, in combination with more accurate first-principles studies, provided insights into the microscopic origin of these levels. Our investigations suggest that the lower level at 0.12 eV might originate from CN, which behaves as a hole trap state; the deeper level at 0.62 eV can be correlated with VGa that corresponds to the yellow luminescence band observed in low-temperature photoluminescence spectra.

  20. Photo- and thermally stimulated luminescence of polyminerals extracted from herbs and spices

    NASA Astrophysics Data System (ADS)

    Cruz-Zaragoza, E.; Marcazzó, J.; Chernov, V.

    2012-08-01

    Ionizing radiation processing is a widely employed method for preservative treatment of foodstuffs. Usually it is possible to detect irradiated herbs and spices by resorting to luminescence techniques, in particular photo- and thermostimulated luminescence. For these techniques to be useful, it is necessary to characterize the response to radiation of each particular herb or spice. In this work, the thermoluminescence (TL) and photostimulated luminescence (PSL) properties of inorganic polymineral fractions extracted from commercial herbs and spices previously irradiated for disinfestation purposes have been analyzed. Samples of mint, cinnamon, chamomile, paprika, black pepper, coriander and Jamaica flower were irradiated from 50 to 400 Gy by using a beta source. The X-ray diffraction (XRD) analysis has shown that the mineral fractions consist mainly of quartz and feldspars. The PSL and TL response as a function of the absorbed dose, and their fading at room temperature have been determined. The TL glow curves have been deconvolved in order to obtain characteristic kinetics parameters in each case. The results of this work show that PSL and TL are reliable techniques for detection and analysis of irradiated foodstuffs.

  1. Lanthanide coordination polymers: Synthesis, diverse structure and luminescence properties

    NASA Astrophysics Data System (ADS)

    Song, Xue-Qin; Lei, Yao-Kun; Wang, Xiao-Run; Zhao, Meng-Meng; Peng, Yun-Qiao; Cheng, Guo-Quan

    2014-10-01

    The new semirigid exo-bidentate ligand incorporating furfurysalicylamide terminal groups, namely, 1,4-bis{[(2‧-furfurylaminoformyl)phenoxyl]methyl}-2,5-bismethylbenzene (L) was synthesized and used as building blocks for constructing lanthanide coordination polymers with luminescent properties. The series of lanthanide nitrate complexes have been characterized by elemental analysis, IR spectroscopy, and X-ray diffraction analysis. The semirigid ligand L, as a bridging ligand, reacts with lanthanide nitrates forming three distinct structure types: chiral noninterpenetrated two-dimensional (2D) honeycomblike (6,3) (hcb, Schläfli symbol 63, vertex symbol 6 6 6) topological network as type I, 1D zigzag chain as type II and 1D trapezoid ladder-like chain as type III. The structural diversities indicate that lanthanide contraction effect played significant roles in the structural self-assembled process. The luminescent properties of EuIII, TbIII and DyIII complexes are discussed in detail. Due to the good match between the lowest triplet state of the ligand and the resonant energy level of the lanthanide ion, the lanthanide ions in EuIII, TbIII and DyIII complexes can be efficiently sensitized by the ligand.

  2. Luminescence properties of defects in GaN

    SciTech Connect

    Reshchikov, Michael A.; Morkoc, Hadis

    2005-03-15

    Gallium nitride (GaN) and its allied binaries InN and AIN as well as their ternary compounds have gained an unprecedented attention due to their wide-ranging applications encompassing green, blue, violet, and ultraviolet (UV) emitters and detectors (in photon ranges inaccessible by other semiconductors) and high-power amplifiers. However, even the best of the three binaries, GaN, contains many structural and point defects caused to a large extent by lattice and stacking mismatch with substrates. These defects notably affect the electrical and optical properties of the host material and can seriously degrade the performance and reliability of devices made based on these nitride semiconductors. Even though GaN broke the long-standing paradigm that high density of dislocations precludes acceptable device performance, point defects have taken the center stage as they exacerbate efforts to increase the efficiency of emitters, increase laser operation lifetime, and lead to anomalies in electronic devices. The point defects include native isolated defects (vacancies, interstitial, and antisites), intentional or unintentional impurities, as well as complexes involving different combinations of the isolated defects. Further improvements in device performance and longevity hinge on an in-depth understanding of point defects and their reduction. In this review a comprehensive and critical analysis of point defects in GaN, particularly their manifestation in luminescence, is presented. In addition to a comprehensive analysis of native point defects, the signatures of intentionally and unintentionally introduced impurities are addressed. The review discusses in detail the characteristics and the origin of the major luminescence bands including the ultraviolet, blue, green, yellow, and red bands in undoped GaN. The effects of important group-II impurities, such as Zn and Mg on the photoluminescence of GaN, are treated in detail. Similarly, but to a lesser extent, the effects of

  3. Synthesis and luminescence properties of KSrPO4:Eu2+ phosphor for radiation dosimetry

    NASA Astrophysics Data System (ADS)

    Palan, C. B.; Bajaj, N. S.; Omanwar, S. K.

    2016-05-01

    The KSrPO4: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 KSrPO4:Eu were studied. The PL spectra show blue emission under near UV excitation. It was advocated that KSrPO4:Eu phosphor not only show OSL sensitivity (0.47 times) but also gives faster decay in OSL signals than that of Al2O3: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.

  4. Independent evaluation of optically stimulated luminescence (OSL) 'dot' dosemeters for environmental monitoring.

    PubMed

    Timilsina, Bindu; Gesell, Thomas F

    2011-01-01

    Optically stimulated luminescence (OSL) 'dot' dosemeters (manufactured by Landauer®) are reported to have a high degree of environmental stability, high level of sensitivity and provide wide range of dose measuring capabilities from 0.05 mGy to 100 Gy. The optical read out method is fast and relatively simple and permits repeated read out, but few studies have been performed about its application in monitoring radiation in the environment. This study was initiated to independently test the performance of OSL dot dosemeters for the application of measuring doses of radiation in the outdoor environment. Testing was performed in the laboratory to evaluate reproducibility and stability and in the field to evaluate accuracy relative to calibrated high-pressure ionisation chambers. The results showed that OSL dot dosemeters had good reproducibility and stability in both laboratory and field tests and met the performance requirements of standards of the American National Standards Institute. PMID:20947590

  5. Detection of irradiated spices using photo-stimulated luminescence technique (PSL)

    SciTech Connect

    Ramli, Ros Anita Ahmad; Yasir, Muhamad Samudi; Othman, Zainon; Abdullah, Wan Saffiey Wan

    2014-09-03

    Photo-stimulated luminescence (PSL) technique was applied to detect irradiated black pepper (Piper nigrum), cinnamon (Cinnamomum verum) and turmeric (Curcuma longa) after dark storage for 1 day, 3 and 6 months. Using screening and calibrated PSL, all samples were correctly discriminated between non-irradiated and spices irradiated with doses 1, 5 and 10 kGy. The PSL photon counts (PCs) of irradiated spices increased with increasing dose, with turmeric showing highest sensitivity index to irradiation compared to black pepper and cinnamon. The differences in response are possibly attributed to the varying quantity and quality of silicate minerals present in each spice sample. PSL signals of all irradiated samples reduced after 3 and 6 months storage. The results of this study provide a useful database on the applicability of PSL technique for the detection of Malaysian irradiated spices.

  6. Detection of irradiated spices using photo-stimulated luminescence technique (PSL)

    NASA Astrophysics Data System (ADS)

    Ramli, Ros Anita Ahmad; Yasir, Muhamad Samudi; Othman, Zainon; Abdullah, Wan Saffiey Wan

    2014-09-01

    Photo-stimulated luminescence (PSL) technique was applied to detect irradiated black pepper (Piper nigrum), cinnamon (Cinnamomum verum) and turmeric (Curcuma longa) after dark storage for 1 day, 3 and 6 months. Using screening and calibrated PSL, all samples were correctly discriminated between non-irradiated and spices irradiated with doses 1, 5 and 10 kGy. The PSL photon counts (PCs) of irradiated spices increased with increasing dose, with turmeric showing highest sensitivity index to irradiation compared to black pepper and cinnamon. The differences in response are possibly attributed to the varying quantity and quality of silicate minerals present in each spice sample. PSL signals of all irradiated samples reduced after 3 and 6 months storage. The results of this study provide a useful database on the applicability of PSL technique for the detection of Malaysian irradiated spices.

  7. A gamma/neutron-discriminating, Cooled, Optically Stimulated Luminescence (COSL) dosemeter

    SciTech Connect

    Eschbach, P.A.; Miller, S.D.

    1992-07-01

    The Cooled Optically Stimulated Luminescence (COSL) of CaF{sub 2}:Mn (grain sizes from 0.1 to 100 microns) powder embedded in a hydrogenous matrix is reported as a function of fast-neutron dose. When all the CaF{sub 2}:Mn grains are interrogated at once, the COSL plastic dosemeters have a minimum detectable limit of 1 cSv fast neutrons; the gamma component from the bare {sup 252}cf exposure was determined with a separate dosemeter. We report here on a proton-recoil-based dosemeter that generates pulse height spectra, much like the scintillator of Hornyak, (2) to provide information on both the neutron and gamma dose.

  8. Depositional pathway tracing in glacial catchments using Optically Stimulated Luminescence dating

    NASA Astrophysics Data System (ADS)

    King, Georgina; Robinson, Ruth; Finch, Adrian

    2010-05-01

    Optically stimulated luminescence (OSL) dating is a direct Quaternary dating method which is utilised to date sedimentary horizons and landforms, and to constrain rates of geomorphological processes in a wide variety of environmental settings. Within cold environments, material suitable for radiocarbon dating is often absent, and OSL has been increasingly used to date glacial deposits. However, one of the prerequisites of OSL, that quartz grains are fully exposed to sunlight prior to deposition, is not necessarily fulfilled in some glacial environments, resulting in partial bleaching of luminescence signals during transport. Typical equivalent doses (De) distributions for partially bleached samples are overdispersed and skewed, which causes reduced precision in age determinations and potential age overestimation. The application of age models has been used by luminescence practitioners to overcome this limitation, however it is hypothesized here that these De distributions contain valuable information about the sampled deposit's depositional history and source. The degree of De overdispersion and the shape of the distribution are in part dependent on transport and depositional processes, and the initial overdispersion characteristics of the sediment source. Numerous depositional pathways operate with varying dominance within glacial catchments depending upon glacier behaviour, climate, bedrock type, catchment morphology, and sediment availability. Mobile sediment may be derived from, and transported within, paraglacial, subglacial, or supraglacial sources, and deposition may occur within ice-contact landforms or within a glaciofluvial environment. Valuable inferences about the transport and depositional pathways operating within an environment may be made if these different pathways have distinctive overdispersion characteristics. If tracing specific signatures is possible, it will provide a means through which the dominant sediment sources and depositional

  9. Optically and thermally stimulated luminescence of KMgF3:Ce3 and NaMgF3:Ce3+.

    PubMed

    Le Masson, N J M; Bos, A J J; Van Eijk, C W E; Furetta, C; Chaminade, J P

    2002-01-01

    The potentialities of optically stimulated luminescence (OSL) for personal dosimetry of ionising radiation have stimulated the search for new synthetic materials with good dosimetric properties. The sensitivity of two new OSL materials KMgF3 and NaMgF3 doped with Ce3+ ions has been evaluated and found to be of the same order of magnitude as that of Al2O3:C. Several other characteristics have also been investigated. Promising results for KMgF3:Ce are the high sensitivity and the low fading. However, this material suffers from a high self-dose due to the presence of 40K. NaMgF5:Ce is sensitive as well but shows strong fading. Interesting information on the mechanism has been obtained by correlating the signals of OSL and TL. Furthermore, the different bleachabilities under blue LED illumination of the strongly overlapping glow peaks allowed the extraction of one single peak for KMgF3:Ce3+. The results demonstrate new possibilities offered by the combination of TL and OSL. PMID:12382866

  10. WE-E-18A-04: Precision In-Vivo Dosimetry Using Optically Stimulated Luminescence Dosimeters and a Pulsed-Stimulating Dose Reader

    SciTech Connect

    Chen, Q; Herrick, A; Hoke, S; Burns, J

    2014-06-15

    Purpose: A new readout technology based on pulsed optically stimulating luminescence is introduced (microSTARii, Landauer, Inc, Glenwood, IL60425). This investigation searches for approaches that maximizes the dosimetry accuracy in clinical applications. Methods: The sensitivity of each optically stimulated luminescence dosimeter (OSLD) was initially characterized by exposing it to a given radiation beam. After readout, the luminescence signal stored in the OSLD was erased by exposing its sensing area to a 21W white LED light for 24 hours. A set of OSLDs with consistent sensitivities was selected to calibrate the dose reader. Higher order nonlinear curves were also derived from the calibration readings. OSLDs with cumulative doses below 15 Gy were reused. Before an in-vivo dosimetry, the OSLD luminescence signal was erased with the white LED light. Results: For a set of 68 manufacturer-screened OSLDs, the measured sensitivities vary in a range of 17.3%. A sub-set of the OSLDs with sensitivities within ±1% was selected for the reader calibration. Three OSLDs in a group were exposed to a given radiation. Nine groups were exposed to radiation doses ranging from 0 to 13 Gy. Additional verifications demonstrated that the reader uncertainty is about 3%. With an external calibration function derived by fitting the OSLD readings to a 3rd-order polynomial, the dosimetry uncertainty dropped to 0.5%. The dose-luminescence response curves of individual OSLDs were characterized. All curves converge within 1% after the sensitivity correction. With all uncertainties considered, the systematic uncertainty is about 2%. Additional tests emulating in-vivo dosimetry by exposing the OSLDs under different radiation sources confirmed the claim. Conclusion: The sensitivity of individual OSLD should be characterized initially. A 3rd-order polynomial function is a more accurate representation of the dose-luminescence response curve. The dosimetry uncertainty specified by the manufacturer

  11. Carboxylato- bis-dibenzoylmethanates of europium(III): Luminescence and magnetic properties

    NASA Astrophysics Data System (ADS)

    Tkachenko, I. A.; Petrochenkova, N. V.; Mirochnik, A. G.; Karasev, V. E.; Kavun, V. Ya.

    2012-04-01

    The luminescent and magnetic properties of europium(III) carboxylates, determined from the structure of Stark and Zeeman sublevels, are studied. It is found that the values of the λlum energy gap between the ground state 7 F 0 and 7 F 1 term in the luminescence spectra and λmagn obtained from magnetochemical measurements correlate well.

  12. Luminescence properties of Si-containing porous matrix–PbS nanoparticle systems

    SciTech Connect

    Tarasov, S. A. Aleksandrova, O. A.; Lamkin, I. A.; Maksimov, A. I.; Maraeva, E. V.; Mikhailov, I. I.; Moshnikov, V. A.; Musikhin, S. F.; Nalimova, S. S.; Permyakov, N. V.; Spivak, Yu. M.; Travkin, P. G.

    2015-12-15

    The luminescence properties of systems that contain lead-sulfide nanoparticles deposited onto substrates fabricated from porous silicon, oxidized porous silicon, and porous (tin-oxide)–(silicon-oxide) layers are studied. It is shown that the structure and composition of the matrix induce a strong effect on the luminescence spectra of colloidal quantum dots, defining their emission wavelength.

  13. Optically stimulated luminescence in LiCaAlF6:Eu2+ phosphor.

    PubMed

    More, Y K; Wankhede, S P; Moharil, S V; Kumar, Munish; Chougaonkar, M P

    2015-09-01

    Results on optically stimulated luminescence (OSL) in LiCaAlF6:Eu(2+) are reported. Continuous wave OSL signal as recorded using blue (470 nm) stimulation was found to be ~31% that of standard phosphor lithium magnesium phosphate. The rate of OSL depletion for standard phosphor lithium magnesium phosphate is only three times less as compared with that of LiCaAlF6:Eu(2+). Strong photoluminescence (PL) in the near ultraviolet region is observed for LiCaAlF6:Eu(2+) with the characteristic Eu(2+) emission at 369 nm for 254 nm excitation. The thermoluminescence (TL) glow peak for LiCaAlF6:Eu(2+) was observed at around 180°C. The glow peak was about six times more intense compared with the dosimetric peak of the well known thermoluminescence dosimetric (TLD) phosphor LiF-TLD 100. Thus this phosphor deserves much more attention than it has received until now and may be useful as a dosimetric material in radiation dosimetry. PMID:25620581

  14. Application of pulsed optically stimulated luminescence from surface soil to retrospective dosimetry

    NASA Astrophysics Data System (ADS)

    Fujita, Hiroki

    2014-11-01

    A novel pulsed optically stimulated luminescence (P-OSL) instrument was developed. The performance of the instrument was tested using natural quartz extracted from Japanese surface soil and feldspar in mineral specimens. The different P-OSL signals for quartz and feldspar were detected from their decay shape. It was found that the signal from feldspar decayed for 2-3 μs and the signal from quartz was measured at over 50 μs after the LED stimulation was switched off. By using a mixture of quartz and feldspar, the P-OSL protocol was improved to determine the irradiation dose. After irradiating a soil sample, a dose recovery test was conducted and the P-OSL protocol was found to be successful in reconstructing the irradiated dose with an on-time pulse of 4 and 10 μs for quartz and feldspar, respectively. Finally, a soil sample illuminated by a solar simulator was irradiated by a gamma source and then was used in the dose recovery test. The estimated dose agreed with the expected dose. From these results, it can be concluded that P-OSL dosimetry is suitable for the evaluation of the effects of a radiation accident, although further research using actual Japanese surface soil is required to improve the protocol.

  15. SU-E-T-264: Preliminary Results On New Optically Stimulated Luminescent Materials for Proton Therapy Dosimetry

    SciTech Connect

    Doull, B; Zheng, Y; Yukihara, E

    2014-06-01

    Purpose: The objective of this work is to test the premise that luminescence materials with less under-response to proton beams can be identified by testing their dose response to low-LET radiation. The goal is to develop new Optically Stimulated Luminescence (OSL) materials with improved response for proton therapy dosimetry. Methods: We first measured the dose response of new OSL materials, synthesized in our laboratory, to low-LET radiation (beta rays from a {sup 90}Sr/{sup 90}Y source) and selected two materials having different OSL saturation characteristics and good dosimetric properties, namely MgB4O7:Ce,Li and MgO:Li. Commercial Al2O3:C was also used for comparison. These materials were then irradiated at several depths along a pristine proton beam. The luminescence responses of the materials, relative to the entrance response, were compared with the depth dose profile measured by a multiple-layer ion chamber. Results: The OSL signals of MgB4O7:Ce,Li and MgO:Li were characterized for signal stability, dose response, and response to a clinical proton beam. The materials were also compared with the commercial Al2O3:C. The signals from both MgB4O7:Ce,Li and MgO:Li were relatively stable after a one day delay following irradiation. The low-LET dose response of the materials showed that, over the dose range investigated (up to ∼800 Gy), MgB4O7:Ce,Li did not saturate, whereas MgO:Li and Al2O3:C saturated at doses of ∼100 Gy. MgB4O7:Ce,Li showed less underresponse to proton beams than MgO:Li and Al2O3:C. Conclusion: In general the material with the highest saturation doses for low-LET radiation (MgB4O7:Ce,Li) showed the least under-response to proton beams, which suggests that it may be possible to develop better OSL materials for proton dosimetry if the dose response can be controlled during synthesis. Nevertheless, the degree in which the response to proton beams can be controlled remains to be determined. The research is funded by the Oklahoma Center for

  16. Experimental setup for camera-based measurements of electrically and optically stimulated luminescence of silicon solar cells and wafers.

    PubMed

    Hinken, David; Schinke, Carsten; Herlufsen, Sandra; Schmidt, Arne; Bothe, Karsten; Brendel, Rolf

    2011-03-01

    We report in detail on the luminescence imaging setup developed within the last years in our laboratory. In this setup, the luminescence emission of silicon solar cells or silicon wafers is analyzed quantitatively. Charge carriers are excited electrically (electroluminescence) using a power supply for carrier injection or optically (photoluminescence) using a laser as illumination source. The luminescence emission arising from the radiative recombination of the stimulated charge carriers is measured spatially resolved using a camera. We give details of the various components including cameras, optical filters for electro- and photo-luminescence, the semiconductor laser and the four-quadrant power supply. We compare a silicon charged-coupled device (CCD) camera with a back-illuminated silicon CCD camera comprising an electron multiplier gain and a complementary metal oxide semiconductor indium gallium arsenide camera. For the detection of the luminescence emission of silicon we analyze the dominant noise sources along with the signal-to-noise ratio of all three cameras at different operation conditions. PMID:21456750

  17. Thermally stimulated luminescence of naphthyl-substituted benzidine derivative and tris-8-(hydroxyquinoline) aluminum with and without metal layers

    SciTech Connect

    Forsythe, E.W.; Morton, D.C.; Gao, Y.

    1998-07-01

    Multilayer organic light emitting devices based on tris-8-(hydroxyquinoline) aluminum (Alq{sub 3}) and a naphthyl-substituted benzidine derivative (NPB) have demonstrated practical electroluminescence with a wide range of color. Trap states in these materials play an important role in the carrier transport as well as the light emission process. The authors report the first observation of thermally stimulated luminescence (TSL) from Alq{sub 3} and NPB. The TSL spectra from 8K to 300K were used to determine the trap states in Alq{sub 3} and NPB. The results for Alq{sub 3} show a significant trap distribution at 156K, which corresponds to a mean trap depth ranging from 0.18 to 0.12 eV, whereas the trap states in NPB are centered from 0.15 eV to 0.01 eV. The authors have used TSL to study the trap state properties of thin metal layers in the Alq{sub 3} films. In addition, they report photoluminescence as a function of temperature for Alq{sub 3}. TSL spectroscopy provides a technique to study the trap states in a specific layer of the device structure.

  18. Investigation of neutron converters for production of optically stimulated luminescence (OSL) neutron dosimeters using Al 2O 3:C

    NASA Astrophysics Data System (ADS)

    Mittani, J. C. R.; da Silva, A. A. R.; Vanhavere, F.; Akselrod, M. S.; Yukihara, E. G.

    2007-07-01

    This paper presents the optically stimulated luminescence (OSL) properties of neutron dosimeters in powder and in the form of pellets prepared with a mixture of Al 2O 3:C and neutron converters. The neutron converters investigated were high density polyethylene (HDPE), lithium fluoride (LiF), lithium fluoride 95% enriched with 6Li ( 6LiF), lithium carbonate 95% enriched with 6Li ( 6Li 2CO 3), boric acid enriched with 99% of 10B (H310BO) and gadolinium oxide (Gd 2O 3). The proportion of Al 2O 3:C and neutron converter in the mixture was varied to optimize the total OSL signal and neutron sensitivity. The neutron sensitivity and dose-response were determined for the OSL dosimeters using a bare 252Cf source and compared to the response of Harshaw TLD-600 and TLD-700 dosimeters ( 6LiF:Mg,Ti and 7LiF:Mg,Ti). The results demonstrate the possibility of developing an OSL dosimeter made of Al 2O 3:C powder and neutron converter with a neutron sensitivity (defined as the ratio between the 60Co equivalent gamma dose and the reference neutron absorbed dose) and neutron-gamma discrimination comparable to the TLD-600/TLD-700 combination. It was shown that the shape of the OSL decay curves varied with the type of the neutron converter, demonstrating the influence of the energy deposition mechanism and ionization density on the OSL process in Al 2O 3:C.

  19. Characterization of optically stimulated luminescence dosemeters to measure organ doses in diagnostic radiology

    PubMed Central

    Endo, A; Katoh, T; Kobayashi, I; Joshi, R; Sur, J; Okano, T

    2012-01-01

    Objective The aim of this study was to assess the characteristics of an optically stimulated luminescence dosemeter (OSLD) for use in diagnostic radiology and to apply the OSLD in measuring the organ doses by panoramic radiography. Methods The dose linearity, energy dependency and angular dependency of aluminium oxide-based OSLDs were examined using an X-ray generator to simulate various exposure settings in diagnostic radiology. The organ doses were then measured by inserting the dosemeters into an anthropomorphic phantom while using three panoramic machines. Results The dosemeters demonstrated consistent dose linearity (coefficient of variation<1.5%) and no significant energy dependency (coefficient of variation<1.5%) under the applied exposure conditions. They also exhibited negligible angular dependency (≤10%). The organ doses of the X-ray as a result of panoramic imaging by three machines were calculated using the dosemeters. Conclusion OSLDs can be utilized to measure the organ doses in diagnostic radiology. The availability of these dosemeters in strip form proves to be reliably advantageous. PMID:22116136

  20. Performance of Al2O3:C optically stimulated luminescence dosimeters for clinical radiation therapy applications.

    PubMed

    Hu, B; Wang, Y; Zealey, W

    2009-12-01

    A commercial Optical Stimulated Luminescence (OSL) dosimetry system developed by Landauer was tested to analyse the possibility of using OSL dosimetry for external beam radiotherapy planning checks. Experiments were performed to determine signal sensitivity, dose response range, beam type/energy dependency, reproducibility and linearity. Optical annealing processes to test OSL material reusability were also studied. In each case the measurements were converted into absorbed dose. The experimental results show that OSL dosimetry provides a wide dose response range, good linearity and reproducibility for the doses up to 800cGy. The OSL output is linear with dose up to 600cGy range showing a maximum deviation from linearity of 2.0% for the doses above 600cGy. The standard deviation in response of 20 dosimeters was 3.0%. After optical annealing using incandescent light, the readout intensity decreased by approximately 98% in the first 30 minutes. The readout intensity, I, decreased after repeated optical annealing as a power law, given by I infinity t (-1.3). This study concludes that OSL dosimetry can provide an alternative dosimetry technique for use in in-vivo dosimetry if rigorous measurement protocols are established. PMID:20169842

  1. The storage of bed material in mountain stream channels as assessed using Optically Stimulated Luminescence dating

    NASA Astrophysics Data System (ADS)

    Thompson, Chris; Rhodes, Ed; Croke, Jacky

    2007-01-01

    A detailed understanding of channel forming and maintenance processes in mountain streams requires some measurement and/or prediction of bed load transport and sediment mobility. Traditional field based measurements of such processes are problematic because of the high formative discharges characteristic of such streams. The application of Optically Stimulated Luminescence (OSL) dating is proposed here as a new way of determining actual residency times of fine sediments and consequently validating selected predictions for the entrainment of sediment in these streams. Model predictions of sediment mobility for selected step-pool and plane-bed channels in a mountain catchment in south eastern Australia are initially calculated using equations of hydraulic competence and the one-dimensional HEC-RAS model. Results indicate that floods exceeding bankfull with recurrence intervals up to 13 years are competent to mobilise the maximum overlying surface grain sizes at both sites. OSL minimum age model results from 7 samples of well bleached quartz in the fine matrix particles indicate general agreement with selected competence equations. The apparent long (100-1400 y) burial age of most of the mineral quartz, however, suggests that competent flows are not able to flush all subsurface fine-bed material. The depth of maximum bed load exchange (flushing) was limited to ≤ twice the depth of the overlying D90 grain size. Application of OSL in this study provides important insight into the nature of storage and flushing of matrix material in mountain streams.

  2. Thermally stimulated luminescence from vapor-transport-equilibrated LiTaO3 crystals

    NASA Astrophysics Data System (ADS)

    Chirila, M. M.; Garces, N. Y.; Halliburton, L. E.; Evans, D. R.; Route, R. K.; Fejer, M. M.

    2003-07-01

    Thermally stimulated luminescence (TSL), optical absorption, and electron paramagnetic resonance (EPR) have been used to characterize the emission of ultraviolet light from undoped LiTaO3. The crystals in this study were grown from a congruent melt and then subjected to a vapor-transport-equilibration (VTE) treatment. Two overlapping TSL peaks occur at 94 and 98 K, with each showing a 350 nm maximum in its spectral emission. These peaks are observed after a 77 K exposure of the crystals to x rays or lasers (266, 325, or 355 nm). Congruent crystals from the same boule (but not VTE treated) produced no measurable emission in similar experiments. During excitation of the VTE-treated crystals at 77 K, holes are localized on oxygen ions, either self-trapped or with a nearby stabilizer, and electrons are trapped at regular Ta5+ ions and at Fe3+ impurities (present at trace levels), where they form Ta4+ and Fe2+ ions. The hole centers and the Fe3+ ions have characteristic EPR spectra, and a broad optical absorption band peaking near 1600 nm is attributed to the Ta4+ electron center. Upon warming, the trapped hole centers formed during the initial excitation become unstable below 100 K and move to Ta4+ ions, thus causing radiative recombination in the TaO6 units.

  3. Studies on new neutron-sensitive dosimeters using an optically stimulated luminescence technique

    NASA Astrophysics Data System (ADS)

    Kulkarni, M. S.; Luszik-Bhadra, M.; Behrens, R.; Muthe, K. P.; Rawat, N. S.; Gupta, S. K.; Sharma, D. N.

    2011-07-01

    The neutron response of detectors prepared using α-Al 2O 3:C phosphor developed using a melt processing technique and mixed with neutron converters was studied in monoenergetic neutron fields. The detector pellets were arranged in two different pairs: α-Al 2O 3:C + 6LiF/α-Al 2O 3:C + 7LiF and α-Al 2O 3:C + high-density polyethylene/α-Al 2O 3:C + Teflon, for neutron dosimetry using albedo and recoil proton techniques. The optically stimulated luminescence response of the Al 2O 3:C + 6,7LiF dosimeter to radiation from a 252Cf source was 0.21, in terms of personal dose equivalent Hp(10) and relative to radiation from a 137Cs source. This was comparable to results obtained with similar detectors prepared using commercially available α-Al 2O 3:C phosphor. The Hp(10) response of the α-Al 2O 3:C + 6,7LiF dosimeters was found to decrease by more than two orders of magnitude with increasing neutron energy, as expected for albedo dosimeters. The response of the α-Al 2O 3:C + high-density polyethylene/α-Al 2O 3:C + Teflon dosimeters was small, of the order of 1% to 2% in terms of Hp(10) and relative to radiation from a 137Cs source, for neutron energies greater than 1 MeV.

  4. Investigation of spectroscopic properties, structure and luminescence spectra of Sm3+ doped zinc bismuth silicate glasses.

    PubMed

    Pal, I; Agarwal, A; Sanghi, S; Aggarwal, M P

    2013-01-15

    The glasses with compositions 20ZnO·(79.5-x)Bi2O3·xSiO2·0.5Sm2O3 (10≤x≤50, mol%) have been synthesized using normal melt-quench technique. Optical absorption and fluorescence spectra of the glasses were recorded at ambient temperature. Judd-Ofelt (J-O) theory has been successfully applied to characterize the absorption and luminescence spectra of these glasses. From the measured intensities of absorption bands of these glasses, the Judd-Ofelt parameters, Ωλ (λ=2, 4, 6) have been evaluated. The variation of Ω2 with Bi2O3 content has been attributed to changes in the asymmetry of the ligand field at the rare earth (RE) ion site (due to structural change) and to changes in RE-O covalency, whereas the variation of Ω6 is found to be strongly dependent on nephlauxetic effect. The shift of the hypersensitive band shows that the covalency of the RE-O decreases with decrease in Bi2O3 content in the host glass. Also, using J-O theory various radiative properties like spontaneous emission probability (Arad), radiative life time (τr), fluorescence branching ratio (βr) and stimulated emission cross-section (σ) for various emission bands of these glasses in the visible spectral region have been determined. A close correlation is observed between the Bi2O3 content and the spectroscopic, radiative and structural properties of the prepared glasses. The values of radiative properties indicated that 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions responsible for orange luminescence might be used in the development of materials for LED's and other optical devices in the visible region. PMID:23099163

  5. Characterization of Fundamental Luminescence Properties of the Mars Soil Simulant JSC Mars-1 and Their Relevance to Absolute Dating of Martian Eolian Sediments

    NASA Astrophysics Data System (ADS)

    Lepper, Kenneth; McKeever, Stephen W. S.

    2000-04-01

    This report explores the potential for luminescence dating techniques to provide absolute age determinations of eolian sediments on the surface of Mars, including those incorporated in the martian polar ice caps. Fundamental thermally and optically stimulated luminescence properties of bulk samples of JSC Mars-1 soil simulant are reported and their relevance to the development of dating procedures is discussed. The radiation-induced luminescence signals (both thermoluminescence, TL, and optically stimulated luminescence, OSL) from JSC Mars-1 are found to have a wide dynamic dose-response range, with the luminescence increasing linearly to the highest doses used (936 Gy), following irradiation with 90Sr/ 90Y beta particles. The signals are also susceptible to solar resetting, with the OSL signals decreasing to <10% of their original levels within the first 20 min of exposure to sunlight. The TL signal also decays rapidly, being reduced to ˜15% within the first 20 min, but reaches a stable, nonzero level at long bleaching times. Neither the TL nor the OSL signals exhibit fading (i.e., loss of signal after irradiation before TL or OSL readout), nor do they exhibit significant sensitivity changes upon repeated irradiation and readout. These three properties (wide dynamic range, solar bleaching, and signal stability) form a stable base for future investigation of the material for luminescence dating and form a preliminary step toward development of dating protocols for terrestrial analogs of Mars surface materials. We conclude that luminescence dating, properly developed, holds the potential to be a valuable tool for absolute dating of martian eolian sediments

  6. Crystal structures and optical properties of new quaternary strontium europium aluminate luminescent nanoribbons

    SciTech Connect

    Li, Xufan; Budai, John D.; Liu, Feng; Chen, Yu-Sheng; Howe, Jane Y.; Sun, Chengjun; Tischler, Jonathan Zachary; Meltzer, Richard; Pan, Zhengwei

    2014-11-12

    We report the synthesis and characterizations of three series of quaternary strontium europium aluminate (Sr-Eu-Al-O; SEAO) luminescent nanoribbons that show blue, green, and yellow luminescence from localized Eu2+ luminescent centers. These three series of SEAO nanoribbons are: blue luminescent, tetragonal Sr1-xEuxAl6O10 (0luminescent, monoclinic Sr1-xEuxAl2O4 (0luminescent, hexagonal Sr1-xEuxAl2O4 (0luminescence properties were investigated. These one-dimensional SEAO luminescent nanoribbons can function as both light generators and waveguides, and thus have promising potential as the building blocks in miniaturized photonic circuitry.

  7. Optically stimulated luminescence (OSL) as a chronometer for surface exposure dating

    NASA Astrophysics Data System (ADS)

    Sohbati, Reza; Murray, Andrew S.; Chapot, Melissa S.; Jain, Mayank; Pederson, Joel

    2012-09-01

    We pioneer a technique of surface-exposure dating based upon the characteristic form of an optically stimulated luminescence (OSL) bleaching profile beneath a rock surface; this evolves as a function of depth and time. As a field illustration of this new method, the maximum age of a premier example of Barrier Canyon Style (BCS) rock art in Canyonlands National Park, Utah, USA, is constrained. The natural OSL signal from quartz grains is measured from the surface to a depth of >10 mm in three different rock samples of the Jurassic Navajo Sandstone. Two samples are from talus with unknown daylight exposure histories; one of these samples was exposed at the time of sampling and one was buried and no longer light exposed. A third sample is known to have been first exposed 80 years ago and was still exposed at the time of sampling. First, the OSL-depth profile of the known-age sample is modeled to estimate material-dependent and environmental parameters. These parameters are then used to fit the model to the corresponding data for the samples of unknown exposure history. From these fits we calculate that the buried sample was light exposed for ˜700 years before burial and that the unburied sample has been exposed for ˜120 years. The shielded surface of the buried talus sample is decorated with rock art; this rock fell from the adjacent Great Gallery panel. Related research using conventional OSL dating suggests that this rockfall event occurred ˜900 years ago, and so we deduce that the rock art must have been created between ˜1600 and 900 years ago. Our results are the first credible estimates of exposure ages based on luminescence bleaching profiles. The strength of this novel OSL method is its ability to establish both ongoing and prior exposure times, at decadal to millennial timescales or perhaps longer (depending on the environmental dose rate) even for material subsequently buried. This has considerable potential in many archeological, geological and geo

  8. Luminescence properties of oxide coatings on aluminum alloys

    NASA Astrophysics Data System (ADS)

    Pershukevich, P. P.; Shabrov, D. V.; Osipov, V. P.; Schreiber, J.; Lapina, V. A.

    2011-09-01

    This is a study of the luminescence properties of coatings formed on aluminum alloys by anodizing in electrolytic solutions based on oxalic, sulfuric, and tartaric-sulfonic acids. At least two emission centers, with band maxima in the ranges of 390-410 and 470-510 nm, can be reliably identified in the photoluminescence spectra. The first type of center is characterized by single-band photoluminescence excitation spectra and the second, by two-band spectra. An analysis of the two-band photoluminescence excitation (PLE) spectra in the range of 470-510 nm shows that the position of the narrow short-wavelength PLE spectrum near 272 nm is independent of the type of acid used in the anodization process. The position and shape of the other PLE spectral bands depend both on the type of acid used and on the processing of the alloy or alumina surfaces. It is assumed that defect-free alumina centers are responsible for the 272 nm PLE band, while the other photoluminescence bands are caused primarily by different divacancies of oxygen ( {F_2^+} , F 2, and {F_2^{+2}} centers) whose origin is governed by the type of electrolyte.

  9. On the luminescence properties of CaSO4:Ce.

    PubMed

    Lapraz, D; Prevost, H; Iacconi, P; Guigues, C; Benabdesselam, M; Briand, D

    2002-01-01

    The luminescent properties of cerium doped calcium sulphate are studied: fluorescence and excitation spectra, optical absorption and thermoluminescence (TSL). It is known that, in rare earth doped CaSO4, only cerium induces a strong 400 degrees C TSL peak. In CaSO4:0.2%Ce samples synthesised under oxidising conditions, the recovery step of Ce3+ fluorescence is correlated with the 400 degrees C TSL peak readout, as mentioned by Nair er al. Our results indicate that an oxidation of Ce3+ ion does occur under X-irradiation (Ce3+ --> Ce4+), followed by a complete return to the trivalent state after thermal annealing at about 500 degrees C; our results confirm the hypothesis of Nair et al that Ce3+ ions are oxidised by ionising irradiation. So, a pure redox reaction seems the most probable for the 400 degrees C TSL peak of CaSO4:Ce. Moreover, the use of the 400 degrees C TSL peak for high temperature dosimetry applications is discussed. PMID:12382899

  10. Luminescence properties of YVO 4:Ln (Ln=Nd, Yb, and Yb-Er) nanoparticles

    NASA Astrophysics Data System (ADS)

    Buissette, V.; Huignard, A.; Gacoin, T.; Boilot, J.-P.; Aschehoug, P.; Viana, B.

    2003-06-01

    Concentrated colloidal solutions of well dispersed YVO 4:Ln (Ln=Nd, Yb, and Yb-Er) nanocrystals are synthesized through the precipitation of citrate complexes of rare earth salts with sodium orthovanadate. Luminescence spectra of aqueous suspensions of YVO 4:Nd or Yb are very similar to the bulk material, with lower lifetimes of the emitting level. After heating at 600 °C, the luminescence properties of silica capped YVO 4:Ln nanoparticles are significantly improved. In these conditions, YVO 4:Yb, Er nanoparticles exhibit green up-conversion luminescence and 1.55 μm emission of the erbium ion under infrared excitation of the ytterbium ion.

  11. Luminescence properties of undoped LiBaAlF6 single crystals.

    PubMed

    Omelkov, S I; Kirm, M; Feldbach, E; Pustovarov, V A; Cholakh, S O; Isaenko, L I

    2010-07-28

    This paper presents the results of the study of electronic excitations in undoped LiBaAlF(6) single crystals by means of luminescence spectroscopy and complimentary optical methods. The intrinsic emission at 4.2 eV due to self-trapped excitons was identified. The fast nanosecond defect-related luminescence was revealed at 3.0 eV. Both emissions degrade under electron beam irradiation, the most probable reason of which is defect creation introducing an additional non-radiative relaxation channel prohibiting energy transfer to luminescence centers. These defects can be recovered and luminescence intensity restored at higher temperatures (>200 K). The permanent damage by electron beam irradiation results only in overall growth of the absorption coefficient in the whole 1.5-6.5 eV spectral region studied. The analysis of thermally stimulated luminescence glow curves in the temperature range of 5-410 K revealed two shallow charge carrier traps with the activation energies of 0.22 and 0.33 eV, respectively. The luminescence of an impurity peaked at 2.5 eV was found and tentatively assigned to an oxygen-related emission center. PMID:21399311

  12. Use of Optically Stimulated Luminescence Imaging Plates and Reader for Arms Control Applications

    SciTech Connect

    Miller, Steven D.; Tomeraasen, Paul L.; Burghard, Brion J.; Traub, Richard J.

    2001-07-05

    Optically Stimulated Luminescence (OSL) technology has been pioneered at the Pacific Northwest National Laboratory (PNNL) for applications in personnel radiation dosimetry and commercially has become highly successful in replacing older technologies such as Thermoluminescence Dosimeters (TLDs) and film. OSL phosphors are used to measure radiation exposure by illuminating them with light after ionizing radiation exposure and measuring the amount of light emitted by the OSL phosphor. By using a two-dimensional plate of OSL material and raster scanning a light beam across the OSL plate a radiation pattern or image can be measured. The Arms Control community requires an electrons-free medium to measure the attributes of extent and symmetry on Pu pits in storage containers. OSL technology, used in the two-dimensional imaging mode, provides a means to measure these attributes with exposure times on the order of an hour. A special OSL reader has been built by PNNL to measure OSL imaging plates with a size of 20 cm by 30 cm. The reader uses 10 light emitting diode clusters with 10 corresponding photomultiplier tubes to measure an OSL imaging plate in less than 5 minutes. The resolution of each of the 10 measurement assemblies is 1 square-centimeter. A collimator assembly employing a Venetian-blind type collimator is used in conjunction with the OSL film to image the Pu pit within the storage container. The output of the OSL reader is a two dimensional array of intensities that will be used with the appropriate information barriers to measure extent and symmetry. This device also clearly distinguishes the difference between a point source and a distributed source. Details of the OSL technology, OSL reader system, collimator design, and system performance will be presented.

  13. An optically stimulated luminescence dosimeter for measuring patient exposure from imaging guidance procedures.

    PubMed

    Ding, George X; Malcolm, Arnold W

    2013-09-01

    There is a growing interest in patient exposure resulting from an x-ray imaging procedure used in image-guided radiation therapy. This study explores a feasibility to use a commercially available optically stimulated luminescence (OSL) dosimeter, nanoDot, for estimating imaging radiation exposure to patients. The kilovoltage x-ray sources used for kV-cone-beam CT (CBCT) imaging acquisition procedures were from a Varian on-board imager (OBI) image system. An ionization chamber was used to determine the energy response of nanoDot dosimeters. The chamber calibration factors for x-ray beam quality specified by half-value layer were obtained from an Accredited Dosimetry Calibration Laboratory. The Monte Carlo calculated dose distributions were used to validate the dose distributions measured by using the nanoDot dosimeters in phantom and in vivo. The range of the energy correction factors for the nanoDot as a function of photon energy and bow-tie filters was found to be 0.88-1.13 for different kVp and bow-tie filters. Measurement uncertainties of nanoDot were approximately 2-4% after applying the energy correction factors. The tests of nanoDot placed on a RANDO phantom and on patient's skin showed consistent results. The nanoDot is suitable dosimeter for in vivo dosimetry due to its small size and manageable energy dependence. The dosimeter placed on a patient's skin has potential to serve as an experimental method to monitor and to estimate patient exposure resulting from a kilovoltage x-ray imaging procedure. Due to its large variation in energy response, nanoDot is not suitable to measure radiation doses resulting from mixed beams of megavoltage therapeutic and kilovoltage imaging radiations. PMID:23920245

  14. Optically stimulated luminescence dating of aeolian sand in the otindag dune field and holocene climate change

    USGS Publications Warehouse

    Zhou, Y.L.; Lu, H.Y.; Mason, J.; Miao, X.D.; Swinehart, J.; Goble, R.

    2008-01-01

    The dune system in Otindag sand field of northern China is sensitive to climate change, where effective moisture and related vegetation cover play a controlling role for dune activity and stability. Therefore, aeolian deposits may be an archive of past environmental changes, possibly at the millennial scale, but previous studies on this topic have rarely been reported. In this study, thirty-five optically stimulated luminescence (OSL) ages of ten representative sand-paleosol profiles in Otindag sand field are obtained, and these ages provide a relatively complete and well-dated chronology for wet and dry variations in Holocene. The results indicate that widespread dune mobilization occurred from 9.9 to 8.2 ka, suggesting a dry early Holocene climate. The dunes were mainly stabilized between 8.0 and 2.7 ka, implying a relatively wet climate, although there were short-term penetrations of dune activity during this wet period. After ???2.3 ka, the region became dry again, as inferred from widespread dune activity. The "8.2 ka" cold event and the Little Ice Age climatic deterioration are detected on the basis of the dune records and OSL ages. During the Medieval Warm Period and the Sui-Tang Warm Period (570-770 AD), climate in Otindag sand field was relatively humid and the vegetation was denser, and the sand dunes were stabilized again. These aeolian records may indicate climate changes at millennial time scale during Holocene, and these climatic changes may be the teleconnection to the climate changes elsewhere in the world. ?? Science in China Press and Springer-Verlag GmbH 2008.

  15. An optically stimulated luminescence dosimeter for measuring patient exposure from imaging guidance procedures

    NASA Astrophysics Data System (ADS)

    Ding, George X.; Malcolm, Arnold W.

    2013-09-01

    There is a growing interest in patient exposure resulting from an x-ray imaging procedure used in image-guided radiation therapy. This study explores a feasibility to use a commercially available optically stimulated luminescence (OSL) dosimeter, nanoDot, for estimating imaging radiation exposure to patients. The kilovoltage x-ray sources used for kV-cone-beam CT (CBCT) imaging acquisition procedures were from a Varian on-board imager (OBI) image system. An ionization chamber was used to determine the energy response of nanoDot dosimeters. The chamber calibration factors for x-ray beam quality specified by half-value layer were obtained from an Accredited Dosimetry Calibration Laboratory. The Monte Carlo calculated dose distributions were used to validate the dose distributions measured by using the nanoDot dosimeters in phantom and in vivo. The range of the energy correction factors for the nanoDot as a function of photon energy and bow-tie filters was found to be 0.88-1.13 for different kVp and bow-tie filters. Measurement uncertainties of nanoDot were approximately 2-4% after applying the energy correction factors. The tests of nanoDot placed on a RANDO phantom and on patient's skin showed consistent results. The nanoDot is suitable dosimeter for in vivo dosimetry due to its small size and manageable energy dependence. The dosimeter placed on a patient's skin has potential to serve as an experimental method to monitor and to estimate patient exposure resulting from a kilovoltage x-ray imaging procedure. Due to its large variation in energy response, nanoDot is not suitable to measure radiation doses resulting from mixed beams of megavoltage therapeutic and kilovoltage imaging radiations.

  16. SU-E-T-75: Commissioning Optically Stimulated Luminescence Dosimeters for Fast Neutron Therapy

    SciTech Connect

    Young, L; Yang, F; Sandison, G; Woodworth, D; McCormick, Z

    2014-06-01

    Purpose: Fast neutrons therapy used at the University of Washington is clinically proven to be more effective than photon therapy in treating salivary gland and other cancers. A nanodot optically stimulated luminescence (OSL) system was chosen to be commissioned for patient in vivo dosimetry for neutron therapy. The OSL-based radiation detectors are not susceptible to radiation damage caused by neutrons compared to diodes or MOSFET systems. Methods: An In-Light microStar OSL system was commissioned for in vivo use by radiating Landauer nanodots with neutrons generated from 50.0 MeV protons accelerated onto a beryllium target. The OSLs were calibrated the depth of maximum dose in solid water localized to 150 cm SAD isocenter in a 10.3 cm square field. Linearity was tested over a typical clinical dose fractionation range i.e. 0 to 150 neutron-cGy. Correction factors for transient signal fading, trap depletion, gantry angle, field size, and wedge factor dependencies were also evaluated. The OSLs were photo-bleached between radiations using a tungsten-halogen lamp. Results: Landauer sensitivity factors published for each nanodot are valid for measuring photon and electron doses but do not apply for neutron irradiation. Individually calculated nanodot calibration factors exhibited a 2–5% improvement over calibration factors computed by the microStar InLight software. Transient fading effects had a significant impact on neutron dose reading accuracy compared to photon and electron in vivo dosimetry. Greater accuracy can be achieved by calibrating and reading each dosimeter within 1–2 hours after irradiation. No additional OSL correction factors were needed for field size, gantry angle, or wedge factors in solid water phantom measurements. Conclusion: OSL detectors are a useful for neutron beam in vivo dosimetry verification. Dosimetric accuracy comparable to conventional diode systems can be achieved. Accounting for transient fading effects during the neutron beam

  17. Optically stimulated luminescence dating of Holocene alluvial fans, East Anatolian Fault System, Turkey

    NASA Astrophysics Data System (ADS)

    Dogan, Tamer; Cetin, Hasan; Yegingil, Zehra; Topaksu, Mustafa; Yüksel, Mehmet; Duygun, Fırat; Nur, Necmettin; Yegingil, İlhami

    2015-07-01

    In this study, the optically stimulated luminescence dating technique was used to determine the time of deposition of alluvial sediment samples from the Türkoğlu-Antakya segment of the East Anatolian Fault System (EAFS) in Turkey. The double-single aliquot regenerative dose protocol on fine grain samples was used to estimate equivalent doses (De). Annual dose rate was computed using elemental concentration of uranium (U) and thorium (Th) determined by using thick-source alpha counting and potassium (K) concentrations using X-ray fluorescence and/or atomic absorption spectroscopy. The environmental dose was measured in situ using α-Al2O3:C chips inside plastic tubes for a year. The two different bulk sediment samples collected from the Islahiye trench yielded ages of 4.54 ± 0.28 and 2.91 ± 0.23 ka. We also obtained a 2.60 ± 0.18 ka age for the alluvial deposit in the Kıranyurdu trench and 2.31 ± 0.14 ka age for an excavation area called Malzeme Ocağı. These ages were consistent with the corresponding calibrated Carbon-14 (14C) ages of the region. The differences between the determined ages were insufficient to clearly distinguish the disturbance event from the effects of bioturbation, biological mixing, or other sources of De variation in the region. They provide a record of alluvial aggradation in the region and may determine undocumented historical earthquake events.

  18. Luminescent and triboluminescent properties of europium(III) hexafluoroacetylacetonate and trifluoroacetate complexes with triphenylphosphine oxide

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Mirochnik, A. G.

    2014-03-01

    Crystalline and strongly luminescent complexes of europium hexafluoroacetylacetonate and trifluoroacetate with triphenylphosphine oxide of Eu(HFAA)3 · 2TPPO and [Eu(TFA)3 · 2TPPO(H2O)]2 composition are synthesized that demonstrating triboluminescent properties. It is established that the measured photoluminescence and triboluminescence spectra of these noncentrosymmetric complex compounds are identical, due to the characteristic f- f-luminescence of the europium(III) ion.

  19. Spectroscopic studies on the lanthanide sensitized luminescence and chemiluminescence properties of fluoroquinolone with different structure.

    PubMed

    Sun, Chunyan; Ping, Hong; Zhang, Minwei; Li, Hongkun; Guan, Fengrui

    2011-11-01

    Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln(3+)). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb(3+)-FQ and Eu(3+)-FQ complexes have been investigated in this contribution. Ce(4+)-SO(3)(2-) in acidic conditions was taken as the CL system and sensitized CL intensities of Tb(3+)-FQ and Eu(3+)-FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb(3+)-FQ complexes show characteristic peaks of Tb(3+) at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb(3+)-ENX, Tb(3+)-NFLX, Tb(3+)-LMFX and Tb(3+)-FLRX display relatively strong emission intensity compared with Tb(3+)-OFLX, Tb(3+)-RFX, Tb(3+)-GFLX and Tb(3+)-SPFX. Quite weak peaks with unique characters of Eu(3+) at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu(3+)-ENX, but no notable sensitized luminescence and CL of Eu(3+) could be observed when Eu(3+) is added into other FQ. The distinct differences on emission intensity of Tb(3+)-FQ and Eu(3+)-FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln(3+). The different sensitized luminescence and CL signals among Tb(3+)-FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb(3+)-FQ and Eu(3+)-FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results. PMID:21821467

  20. Spectroscopic studies on the lanthanide sensitized luminescence and chemiluminescence properties of fluoroquinolone with different structure

    NASA Astrophysics Data System (ADS)

    Sun, Chunyan; Ping, Hong; Zhang, Minwei; Li, Hongkun; Guan, Fengrui

    2011-11-01

    Lanthanide sensitized luminescence and chemiluminescence (CL) are of great importance because of the unique spectral properties, such as long lifetime, large Stokes shifts, and narrow emission bands characteristic to lanthanide ions (Ln 3+). With the fluoroquinolone (FQ) compounds including enoxacin (ENX), norfloxacin (NFLX), lomefloxacin (LMFX), fleroxacin (FLRX), ofloxacin (OFLX), rufloxacin (RFX), gatifloxacin (GFLX) and sparfloxacin (SPFX), the luminescence and CL properties of Tb 3+-FQ and Eu 3+-FQ complexes have been investigated in this contribution. Ce 4+-SO 32- in acidic conditions was taken as the CL system and sensitized CL intensities of Tb 3+-FQ and Eu 3+-FQ complexes were determined by flow-injection analysis. The luminescence and CL spectra of Tb 3+-FQ complexes show characteristic peaks of Tb 3+ at 490 nm, 545 nm, 585 nm and 620 nm. Complexes of Tb 3+-ENX, Tb 3+-NFLX, Tb 3+-LMFX and Tb 3+-FLRX display relatively strong emission intensity compared with Tb 3+-OFLX, Tb 3+-RFX, Tb 3+-GFLX and Tb 3+-SPFX. Quite weak peaks with unique characters of Eu 3+ at 590 nm and 617 nm appear in the luminescence and CL spectra of Eu 3+-ENX, but no notable sensitized luminescence and CL of Eu 3+ could be observed when Eu 3+ is added into other FQ. The distinct differences on emission intensity of Tb 3+-FQ and Eu 3+-FQ might originate from the different energy gap between the triplet levels of FQ and the excited levels of the Ln 3+. The different sensitized luminescence and CL signals among Tb 3+-FQ complexes could be attributed to different optical properties and substituents of these FQ compounds. The detailed mechanism involved in the luminescence and CL properties of Tb 3+-FQ and Eu 3+-FQ complexes has been investigated by analyzing the luminescence and CL spectra, quantum yields, and theoretical calculation results.

  1. Application of optically stimulated luminescence technique to evaluate simultaneously accumulated and single doses with the same dosimeter

    NASA Astrophysics Data System (ADS)

    Malthez, Anna Luiza M. C.; Freitas, Marcelo B.; Yoshimura, Elisabeth M.; Button, Vera L. S. N.

    2014-02-01

    Optically stimulated luminescence dosimeters (OSLD) can be read several times with a negligible loss (degradation) of signal. In this work, we explore this OSL property to estimate simultaneously the accumulated and single doses using a unique Al2O3 dosimeter, irradiated repeated times along over 4 months. This was done through several irradiations of OSLD (Landauer Luxel Dots) with two energies (28 keV X-rays and 1.25 MeV Co-60 gamma rays) and several doses distributed over time. Thermoluminescent dosimeters (TLD) were used as a reference to compare the estimated doses obtained with OSLD. For each irradiation, and both energies, a calibration curve was evaluated with OSLD and TLD to estimate the dose values. The OSL readouts were made with a MicroStar (Landauer) OSL reader. To estimate background (BG) over time, a set of OSLD and TLD (Bycron TLD100) was not irradiated and BG was monitored at each readout section. After irradiations, the OSL and TL signals were converted to dose and values were compared. As a set of OSLD suffered no bleaching after the readouts, it was possible to estimate simultaneously the accumulated and single doses with a unique OSLD. Each single dose was estimated through the subtraction of successive accumulated doses determined for each single OSLD. We concluded that the single doses determined by OSL and TL techniques were compatible, and that the accumulated dose, obtained with OSL technique was comparable to the sum of single doses determined with TLD. We can conclude that using OSL technique and Al2O3 dosimeters it is possible to estimate simultaneously accumulated and single doses with the same dosimeter irradiated with low or high energy photons.

  2. Unusual luminescent properties of water: the major component of biological fluids

    NASA Astrophysics Data System (ADS)

    Lobyshev, Valentin I.; Shihlinskaya, Rogneda E.

    1997-05-01

    It was found that distilled water possesses weak luminescence in the near UV and visible regions of the spectrum. The excitation spectrum is complex and has two main maxima, at 270 and 310 nm. The corresponding emission spectra apart from a narrow lines due to Raman scattering are represented by wide lines at 360 and 410 nm and are determined by the inherent properties of water. The intensity of luminescence depends on the time of holding of a sample in a closed vessel and the addition of a small amount of both luminescent and non-luminescent dipeptides. The observed phenomena can not be reduced to the luminescence of admixtures in water, but is a result of unique properties of water, its structure and polymorphism. The effect of water 'hardening' occurring upon rapid cooling of a hot sample to a room temperature, in contrast to slow cooling, is discovered. It is attributed to the formation of a new steady state of an aqueous structure, indicating by very intensive luminescence band at 5450 nm. Relative intensities of the described bands of emission are greatly sensitive to weak fields of electromagnetic nature. The phenomena observed lead to the conclusion that water and aqueous solutions should be regarded as a continuous polymorphous containing defects structures which are in general non-equilibrium self-organizing systems.

  3. Spectroscopic properties and luminescence behavior of Nd3+ doped zinc alumino bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Mahamuda, Sk.; Swapna, K.; Srinivasa Rao, A.; Jayasimhadri, M.; Sasikala, T.; Pavani, K.; Rama Moorthy, L.

    2013-09-01

    Zinc Alumino Bismuth Borate (ZnAlBiB) glasses doped with different concentrations of neodymium are prepared by using the melt quenching technique to study their physical, absorption and luminescence properties to understand the lasing potentialities of these glasses. From the absorption spectra various spectroscopic parameters and Judd-Ofelt (JO) parameters are evaluated. These JO parameters are used to calculate the transition probability (A), radiative lifetime (τR), and branching ratios (βR) for most of the fluorescent levels of Nd3+. The emission spectra recorded for these glasses gives three prominent transitions 4F3/2→4I9/2, 4F3/2→4I11/2 and 4F3/2→4I13/2 for which effective band widths (ΔλP) and stimulated emission cross-sections (σse) are evaluated. Branching ratios and stimulated emission cross-sections measured for all these glasses show that the 4F3/2→4I11/2 transition under investigation has the potential for laser applications. The intensity of Nd3+ emission spectra increases with increasing concentrations of Nd3+ up to 1 mol% and beyond 1 mol% the concentration quenching is observed. The high stimulated emission cross-section and branching ratios from the present glasses suggests their potential for infrared lasers. From the absorption and emission spectral studies it was found that, 1 mol% of Nd3+ ion concentration is optimum for Zinc Alumino Bismuth Borate glasses to generate a strong laser emission at 1060 nm.

  4. The evaluation of CaF 2:Mn-polyethylene detectors with the aid of the optically stimulated luminescence (OSL)

    NASA Astrophysics Data System (ADS)

    Henniger, Jürgen; Horlbeck, Bernd; Hübner, Klaus; Prokert, Konrad

    1982-12-01

    A serious problem in using TL detectors for neutron dosimetry is their low sensitivity to fast neutrons. Therefore, radiator-detector combinations are employed. But in this case the restricted temperature stability of the radiator material is disadvantageous. This difficulty can be overcome by using the optically stimulated luminescence (OSL). The production of suitable detectors for OSL dosimetry and a convenient evaluation equipment are described. The results given for CaF 2:Mn-polyethylene detectors show that OSL evaluation is useful for dosimetry in mixed neutron gamma fields.

  5. Visible light stimulating dual-wavelength emission and O vacancy involved energy transfer behavior in luminescence for coaxial nanocable arrays

    SciTech Connect

    Yang, Lei; Dong, Jiazhang; Jiang, Zhongcheng; Pan, Anlian; Zhuang, Xiujuan

    2014-06-14

    We report a strategy to investigate O vacancy (V{sub O}) involved energy transfer and dual-wavelength yellow emission in coaxial nanocable. By electric field deposition and subsequent sol-gel template approach, ZnO:Tb/Y{sub 2}O{sub 3}:Eu coaxial nanocable arrays are synthesized. After visible light excitation, system is promoted to O vacancy charge transfer state of V{sub O}(0/+). In the following cross relaxation, energy transfer from V{sub O} to the excitation energy level of Tb{sup 3+} in ZnO:Tb core area. While in Y{sub 2}O{sub 3}:Eu shell area, energy transfer to the excitation energy level of Eu{sup 3+}. Subsequently, dual-wavelength emission is observed. By constructing nanocable with dual-wavelength emission, yellow luminescence is obtained. Adjust doping concentration of Eu{sup 3+} or Tb{sup 3+} in the range of 0.01–0.05, chromaticity coordinates of ZnO:Tb/Y{sub 2}O{sub 3}:Eu nanocable stably stays at yellow region in color space except ZnO:Tb{sub 0.01}/Y{sub 2}O{sub 3}:Eu{sub 0.01}. As Vo states act as media in energy transfer process in nanocablers, visible light can stimulate dual-wavelength emissions. Yellow luminescent nanocable arrays will have great applications in light-emitting diode luminescence.

  6. Visible light stimulating dual-wavelength emission and O vacancy involved energy transfer behavior in luminescence for coaxial nanocable arrays

    NASA Astrophysics Data System (ADS)

    Yang, Lei; Dong, Jiazhang; Jiang, Zhongcheng; Pan, Anlian; Zhuang, Xiujuan

    2014-06-01

    We report a strategy to investigate O vacancy (VO) involved energy transfer and dual-wavelength yellow emission in coaxial nanocable. By electric field deposition and subsequent sol-gel template approach, ZnO:Tb/Y2O3:Eu coaxial nanocable arrays are synthesized. After visible light excitation, system is promoted to O vacancy charge transfer state of VO(0/+). In the following cross relaxation, energy transfer from VO to the excitation energy level of Tb3+ in ZnO:Tb core area. While in Y2O3:Eu shell area, energy transfer to the excitation energy level of Eu3+. Subsequently, dual-wavelength emission is observed. By constructing nanocable with dual-wavelength emission, yellow luminescence is obtained. Adjust doping concentration of Eu3+ or Tb3+ in the range of 0.01-0.05, chromaticity coordinates of ZnO:Tb/Y2O3:Eu nanocable stably stays at yellow region in color space except ZnO:Tb0.01/Y2O3:Eu0.01. As Vo states act as media in energy transfer process in nanocablers, visible light can stimulate dual-wavelength emissions. Yellow luminescent nanocable arrays will have great applications in light-emitting diode luminescence.

  7. Constraining Middle Pleistocene Glaciations in Birmingham, England; Using Optical Stimulated Luminescence (OSL) Dating.

    NASA Astrophysics Data System (ADS)

    Gibson, S. M.; Gibbard, P. L.; Bateman, M. D.; Boreham, S.

    2014-12-01

    Birmingham is built on a complex sequence of Middle Pleistocene sediments, representing at least three lowland glaciations (MIS12, MIS6, and MIS2). British Geological Survey mapping accounts 75% of the land mass as Quaternary deposits; predominantly glacial-sandy tills, glacial-fluvial sands, clays and organic silts and peats. Understanding the age of fluvial-glacial outwash, related to specific glaciations, is critical in establishing a Geochronology of Birmingham. Shotton (1953) found a series of Middle Pleistocene glacial sediments, termed the Wolstonian, intermediate in age between MIS11 and MIS5e Interglacial's. Uncertainty surrounding the relation to East Anglian sequences developed by Rose (1987) implies Birmingham sequences should be referred to MIS12. Despite this, younger Middle Pleistocene glacial sequences occur in Birmingham, yet uncertainty has deepened over our understanding of the complex, inaccessible sediments, especially as deposits have similar extent with MIS2 sequences. Five Optical Stimulated Luminescence (OSL) dates from three sites around Birmingham have been sampled. East of Birmingham, ice advanced from the Irish Sea and later the North East. In Wolston, a sample of outwash sand, associated with the Thurssington Till, is dated. In Meriden, two samples of outwash sands, associated with a distal Oadby Till, are dated. West of Birmingham, ice advanced from the Welsh Ice Sheet. In Seisdon, two samples of an Esker and outwash sand, associated with a Ridgeacre Till, are dated. Correlation of OSL dates provide an important constraint on understanding the history of Birmingham. Using GSI3D modeling to correlate geochronology and sedimentology, the significance of OSL dating can be understood within the complex sequences (and regional stratigraphy), complimented by Cosmogenic and Palynology dates taken in South West and North East. OSL dating on Birmingham's outwash sands, deposited by extensive repeated Middle Pleistocene glaciations, asserts the

  8. On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy.

    PubMed

    Yusof, Fasihah Hanum; Ung, Ngie Min; Wong, Jeannie Hsiu Ding; Jong, Wei Loong; Ath, Vannyat; Phua, Vincent Chee Ee; Heng, Siew Ping; Ng, Kwan Hoong

    2015-01-01

    This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments. PMID:26052690

  9. On the Use of Optically Stimulated Luminescent Dosimeter for Surface Dose Measurement during Radiotherapy

    PubMed Central

    Yusof, Fasihah Hanum; Ung, Ngie Min; Wong, Jeannie Hsiu Ding; Jong, Wei Loong; Ath, Vannyat; Phua, Vincent Chee Ee; Heng, Siew Ping; Ng, Kwan Hoong

    2015-01-01

    This study was carried out to investigate the suitability of using the optically stimulated luminescence dosimeter (OSLD) in measuring surface dose during radiotherapy. The water equivalent depth (WED) of the OSLD was first determined by comparing the surface dose measured using the OSLD with the percentage depth dose at the buildup region measured using a Markus ionization chamber. Surface doses were measured on a solid water phantom using the OSLD and compared against the Markus ionization chamber and Gafchromic EBT3 film measurements. The effect of incident beam angles on surface dose was also studied. The OSLD was subsequently used to measure surface dose during tangential breast radiotherapy treatments in a phantom study and in the clinical measurement of 10 patients. Surface dose to the treated breast or chest wall, and on the contralateral breast were measured. The WED of the OSLD was found to be at 0.4 mm. For surface dose measurement on a solid water phantom, the Markus ionization chamber measured 15.95% for 6 MV photon beam and 12.64% for 10 MV photon beam followed by EBT3 film (23.79% and 17.14%) and OSLD (37.77% and 25.38%). Surface dose increased with the increase of the incident beam angle. For phantom and patient breast surface dose measurement, the response of the OSLD was higher than EBT3 film. The in-vivo measurements were also compared with the treatment planning system predicted dose. The OSLD measured higher dose values compared to dose at the surface (Hp(0.0)) by a factor of 2.37 for 6 MV and 2.01 for 10 MV photon beams, respectively. The measurement of absorbed dose at the skin depth of 0.4 mm by the OSLD can still be a useful tool to assess radiation effects on the skin dermis layer. This knowledge can be used to prevent and manage potential acute skin reaction and late skin toxicity from radiotherapy treatments. PMID:26052690

  10. Recent developments of optically stimulated luminescence materials and techniques for radiation dosimetry and clinical applications

    PubMed Central

    Pradhan, A. S.; Lee, J. I.; Kim, J. L.

    2008-01-01

    During the last 10 years, optically stimulated luminescence (OSL) has emerged as a formidable competitor not only to thermoluminescence dosimetry (TLD) but also to several other dosimetry systems. Though a large number of materials have been synthesized and studied for OSL, Al2O3:C continues to dominate the dosimetric applications. Re-investigations of OSL in BeOindicate that this material might provide an alternative to Al2O3:C. Study of OSL of electronic components of mobile phones and ID cards appears to have opened up a feasibility of dosimetry and dose reconstruction using the electronic components of gadgets of everyday use in the events of unforeseen situations of radiological accidents, including the event of a dirty bomb by terrorist groups. Among the newly reported materials, a very recent development of NaMgF3:Eu2+ appears fascinating because of its high OSL sensitivity and tolerable tissue equivalence. In clinical dosimetry, an OSL as a passive dosimeter could do all that TLD can do, much faster with a better or at least the same efficiency; and in addition, it provides a possibility of repeated readout unlike TLD, in which all the dose information is lost in a single readout. Of late, OSL has also emerged as a practical real-time dosimeter for in vivo measurements in radiation therapy (for both external beams and brachytherapy) and in various diagnostic radiological examinations including mammography and CT dosimetry. For in vivo measurements, a probe of Al2O3:C of size of a fraction of a millimeter provides the information on both the dose rate and the total dose from the readout of radioluminescence and OSL signals respectively, from the same probe. The availability of OSL dosimeters in various sizes and shapes and their performance characteristics as compared to established dosimeters such as plastic scintillation dosimeters, diode detectors, MOSFET detectors, radiochromic films, etc., shows that OSL may soon become the first choice for point dose

  11. Rare earth fluoride nano-/microstructures: hydrothermal synthesis, luminescent properties and applications.

    PubMed

    Zhao, Qian; Xu, Zhenhe; Sun, Yaguang

    2014-02-01

    Rare earth fluoride materials have attracted wide interest and come to the forefront in nanophotonics due to their distinct electrical, optical and magnetic properties as well as their potential applications in diverse fields such as optical telecommunication, lasers, biochemical probes, infrared quantum counters, and medical diagnostics. This review presents a comprehensive overview of the flourishing field of rare earth fluorides materials in the past decade. We summarize the recent research progress on the preparation, morphology, luminescent properties and application of rare earth fluoride-based luminescent materials by hydrothermal systems. Various rare earth fluoride materials are obtained by fine-tuning of experimental conditions, such as capping agents, fluoride source, acidity, temperature and reaction time. The controlled morphology, luminescent properties and application of the rare earth fluorides are briefly discussed with typical examples. PMID:24749449

  12. Luminescence properties of Yb:Er:KY3F10 nanophosphor and thermal treatment effects

    NASA Astrophysics Data System (ADS)

    Gomes, Laércio; Linhares, Horácio Marconi da Silva M. D.; Ichikawa, Rodrigo Uchida; Martinez, Luis Gallego; Baldochi, Sonia Licia

    2016-04-01

    In this work, we present the spectroscopic properties of KY3F10 nanocrystals activated with erbium and codoped with ytterbium ions. The most important processes that lead to the erbium upconversion of green and red emissions of Er3+ were identified. A time-resolved luminescence spectroscopy technique was employed to measure the luminescence decays of 4S3/2 and 4F9/2 excited levels of Er3+ and to determine the upconversion processes and the luminescence efficiencies of erbium in the visible. Analysis of the luminescence kinetics in Yb:Er:KY3F10 shows a rapid upconversion (Up1) for the green emission with a time constant of 0.31 μs after pulsed laser excitation at 972 nm for as synthesized nanocrystals, which is faster than the time constant measured for the bulk crystal (23 μs). In addition, it is observed a second upconversion process (non-resonant) (Up2) responsible for the red emission (Er3+), which competes with Up1 process. However, the luminescence efficiency of the green emission (4S3/2) is observed to be very low (1.6%) for the as synthesized nanocrystal (25 °C). Nevertheless, it increases with the nanopowder heat treatment reaching an efficiency of 99% (T = 550 °C) relative to the bulk crystal. Similar luminescence behavior was observed for the 4F9/2 level (Er3+) that emits red emission. X-ray diffraction analysis of nanopowder by Rietveld method reveled that the mean crystallite size remains unchanged (8.3-12.3 nm) after thermal treatments with T ∼ 400 °C, while the 4S3/2 luminescence efficiency strongly increases to 20%. The luminescence dynamics indicates that Er3+ ions distribution plays a determinant role in the luminescence efficiency of green and red emissions of Er3+ besides also the strong influence on the upconversions processes. The observed luminescence effect is caused by the non-uniform Er3+ (and Yb3+) ions distribution due to the nanocrystal grown, which introduces a concentration gradient that increases towards the nanoparticle

  13. A novel 2D porous indium coordination polymer with tunable luminescent property

    NASA Astrophysics Data System (ADS)

    Li, Xuejiao; Wang, Fangfang; Yang, He; Xu, Bo; Li, Cuncheng

    2016-08-01

    A new Indium coordination polymer [In(pda)1.5(phen)]n1 based on 1,4-phenylenediacetic acid (H2pda) and phen = 1,10-phenanthroline was obtained under hydrothermal condition and further characterized by single crystal X-ray analysis and other physicochemical studies such as infrared spectrum (IR), elemental analysis, thermogravimetric analysis (TGA) and powder X-ray diffraction (PXRD). Structure analysis reveals that complex 1 exhibits 2D porous (6,3) connected layer structure. Luminescent property of 1 was investigated both in the solid state and in different solvents and the results indicated that complex 1 demonstrates distinct solvent dependent luminescent property.

  14. Luminescent and magnetic properties of europium compounds with cinnamic acid

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Tkachenko, I. A.; Mirochnik, A. G.; Karasev, V. E.; Kavun, V. Ya.

    2011-03-01

    The temperature dependences of the molar magnetic susceptibility of luminescent europium compounds with cinnamic acid [Eu(Cin)3] n and Eu(Cin)3 · 2D · H2O (where Cin is the cinnamic acid anion and D is phen (1,10-phenanthroline) or dipy (2,2-dipyridyl)) were studied at temperatures from 300 to 2 K. The molar magnetic susceptibility of the compounds increased in the series Eu(Cin)3 · 2dipy · H2O < Eu(Cin)3 · 2phen · H2O < [Eu(Cin)3] n . The energy distances λlum between the 7 F 0 ground level and the 7 F 1 state in the luminescence spectra correlated well with λmagn obtained from magnetochemical data.

  15. Luminescence Properties of ScPO{sub 4} Single Crystals

    SciTech Connect

    Boatner, L.A.; Trukhin, A.N.

    1999-08-16

    Flux-grown ScPO{sub 4} single crystals exhibit a number of luminescence bands in their x-ray-excited luminescence spectra - including sharp lines arising from rare-earth elements plus a number of broad bands at 5.6 cV, 4.4 eV, and 3 eV. The band at 5.6 eV was attributed to a self-trapped exciton (STE) [l], and it could be excited at 7 eV and higher energies. This luminescence is strongly polarized (P = 70 %) along the optical axes of the crystal and exhibits a kinetic decay time constant that varies from several ns at room temperature to {approximately}10 {micro}s at 60 K and up to {approximately}1 ms at 10 K. It is assumed that the STE is localized on the SC ions. The band at 3 eV can be excited in the range of the ScPO{sub 4} crystal transparency (decay time = 3 to 4 {micro}s.) This band is attributed to a lead impurity that creates different luminescence centers. At high temperatures, the band at 4.4 eV is dominant in the x-ray-excited TSL and afterglow spectra. Its intensity increases with irradiation time beginning at zero at the initial irradiation time. The 4.4 eV band does not appear in a fast process under a pulsed electron beam, showing that accumulation is necessary for its observation. A sample of ScPO{sub 4} doped with vanadium exhibited a prevalent band at 4.4 eV at T = 480 K.

  16. Luminescent Properties of Terbium Aminobenzoates in Condensed Media

    NASA Astrophysics Data System (ADS)

    Meshkova, S. B.; Doga, P. G.; Kiriyak, A. V.; Kucher, A. A.

    2015-07-01

    The decrease in nonradiative deactivation of the luminescence excitation energy in a series of condensed media (true complex solution, viscous solution of water-soluble polymer, polymer fi lm) was studied using terbium complexes with aminobenzoic acids as examples. It was established that the infl uence of the water-soluble polymer was caused by the coordination of Tb3+ to it and the solution viscosity.

  17. Luminescent bichromophoric spiroindolones--synthesis and electronic properties.

    PubMed

    Schönhaber, Jan; Müller, Thomas J J

    2011-09-21

    Novel bichromophoric spirocyclic indolones have been synthesized by an insertion-coupling-isomerization-Diels-Alder domino reaction. The emission colors are strongly affected by the substituents: N-Boc leads to intense blue fluorescence, N-dansyl causes turquoise emission, whereas a 1-anthryl substituent on the butadiene results in yellow luminescence. The latter behavior is rationalized by TDDFT computations as a result of significant geometrical changes. PMID:21796319

  18. Photoluminescence, optically stimulated luminescence, and thermoluminescence study of RbMgF{sub 3}:Eu{sup 2+}

    SciTech Connect

    Dotzler, C.; Williams, G. V. M.; Robinson, J.; Rieser, U.

    2009-01-15

    Optically stimulated luminescence (OSL) and thermoluminescence are observed in polycrystalline RbMgF{sub 3}:Eu{sup 2+} after x-ray, {gamma}-ray, or {beta} irradiation. The main electron traps are F-centers but there are other unidentified traps. The main hole traps at room temperature are probably Eu{sup 3+} and thermal or optical stimulation leads to electron-hole recombination at the Eu{sup 3+} site and Eu{sup 2+} emissions arising from {sup 6}P{sub J} to {sup 8}S{sub 7/2} and 4f{sup 5}d(E{sub g}) to {sup 8}S{sub 7/2} transitions. We find that some of the electron traps can be emptied by infrared stimulation and all of the electron traps can be emptied by white light stimulation. The OSL dark decay is long and exceeds 5 days for traps that are emptied by white light stimulation after initial infrared bleaching. Our results show that this compound can be used as a radiation dosimeter for intermediate dose levels where the {sup 87}Rb self-dose does not significantly affect the dose reading.

  19. Structure and luminescent properties of complex compounds of tellurium(IV) with ammonium bases

    NASA Astrophysics Data System (ADS)

    Sedakova, T. V.; Mirochnik, A. G.

    2015-07-01

    Using tellurium(IV) complex compounds with outer-sphere ammonium cations as an example, we have studied the interrelation between their geometric structure and spectral-luminescent properties. In the series of compounds of tellurium(IV), which are characterized by the island octahedral coordination of Te(IV) ions, the luminescence intensity has been found to depend on the degree of distortion of the coordination polyhedron of the Te(IV) ion, the position of the A band in diffuse reflection spectra, and the energy of the luminescence transition 3 P 1 → 1 S 0 of the tellurium(IV) ion. We have revealed that the considered Te(IV) complexes possess reversible thermochromic properties.

  20. Luminescent properties of europium(III) and terbium(III) complexes with para- and ortho-ethoxybenzoic acids

    NASA Astrophysics Data System (ADS)

    Panyushkin, V. T.; Mutuzova, M. Kh.; Shamsutdinova, M. Kh.

    2016-02-01

    The luminescent properties of europium(III) and terbium(III) complexes with para- and ortho-ethoxybenzoic acids are studied. The excitation energies of the triplet states of ligands are determined, a hypothesis is made about the efficient luminescence of europium(III) and terbium(III) complexes, the geometry of the coordination polyhedron of a europium complex is established, and the luminescence quantum yields of the complexes in solution are determined.

  1. Application of the optically stimulated luminescence (OSL) technique for mouse dosimetry in micro-CT imaging

    SciTech Connect

    Vrigneaud, Jean-Marc; Courteau, Alan; Oudot, Alexandra; Collin, Bertrand; Ranouil, Julien; Morgand, Loïc; Raguin, Olivier; Walker, Paul; Brunotte, François

    2013-12-15

    Purpose: Micro-CT is considered to be a powerful tool to investigate various models of disease on anesthetized animals. In longitudinal studies, the radiation dose delivered by the micro-CT to the same animal is a major concern as it could potentially induce spurious effects in experimental results. Optically stimulated luminescence dosimeters (OSLDs) are a relatively new kind of detector used in radiation dosimetry for medical applications. The aim of this work was to assess the dose delivered by the CT component of a micro-SPECT (single-photon emission computed tomography)/CT camera during a typical whole-body mouse study, using commercially available OSLDs based on Al{sub 2}O{sub 3}:C crystals.Methods: CTDI (computed tomography dose index) was measured in micro-CT with a properly calibrated pencil ionization chamber using a rat-like phantom (60 mm in diameter) and a mouse-like phantom (30 mm in diameter). OSLDs were checked for reproducibility and linearity in the range of doses delivered by the micro-CT. Dose measurements obtained with OSLDs were compared to those of the ionization chamber to correct for the radiation quality dependence of OSLDs in the low-kV range. Doses to tissue were then investigated in phantoms and cadavers. A 30 mm diameter phantom, specifically designed to insert OSLDs, was used to assess radiation dose over a typical whole-body mouse imaging study. Eighteen healthy female BALB/c mice weighing 27.1 ± 0.8 g (1 SD) were euthanized for small animal measurements. OLSDs were placed externally or implanted internally in nine different locations by an experienced animal technician. Five commonly used micro-CT protocols were investigated.Results: CTDI measurements were between 78.0 ± 2.1 and 110.7 ± 3.0 mGy for the rat-like phantom and between 169.3 ± 4.6 and 203.6 ± 5.5 mGy for the mouse-like phantom. On average, the displayed CTDI at the operator console was underestimated by 1.19 for the rat-like phantom and 2.36 for the mouse

  2. Nanoscale coordination polymers exhibiting luminescence properties and NMR relaxivity

    NASA Astrophysics Data System (ADS)

    Chelebaeva, Elena; Larionova, Joulia; Guari, Yannick; Ferreira, Rute A. S.; Carlos, Luis D.; Trifonov, Alexander A.; Kalaivani, Thangavel; Lascialfari, Alessandro; Guérin, Christian; Molvinger, Karine; Datas, Lucien; Maynadier, Marie; Gary-Bobo, Magali; Garcia, Marcel

    2011-03-01

    This article presents the first example of ultra-small (3-4 nm) magneto-luminescent cyano-bridged coordination polymer nanoparticles Ln0.333+Gdx3+/[Mo(CN)8]3- (Ln = Eu (x = 0.34), Tb (x = 0.35)) enwrapped by a natural biocompatible polymer chitosan. The aqueous colloidal solutions of these nanoparticles present a luminescence characteristic of the corresponding lanthanides (5D0 --> 7F0-4 (Eu3+) or the 5D4 --> 7F6-2 (Tb3+)) under UV excitation and a green luminescence of the chitosan shell under excitation in the visible region. Magnetic Resonance Imaging (MRI) efficiency, i.e. the nuclear relaxivity, measurements performed for Ln0.333+Gdx3+/[Mo(CN)8]3- nanoparticles show r1p and r2p relaxivities slightly higher than or comparable to the ones of the commercial paramagnetic compounds Gd-DTPA® or Omniscan® indicating that our samples may potentially be considered as a positive contrast agent for MRI. The in vitro studies performed on these nanoparticles show that they maybe internalized into human cancer and normal cells and well detected by fluorescence at the single cell level. They present high stability even at low pH and lack of cytotoxicity both in human cancer and normal cells.This article presents the first example of ultra-small (3-4 nm) magneto-luminescent cyano-bridged coordination polymer nanoparticles Ln0.333+Gdx3+/[Mo(CN)8]3- (Ln = Eu (x = 0.34), Tb (x = 0.35)) enwrapped by a natural biocompatible polymer chitosan. The aqueous colloidal solutions of these nanoparticles present a luminescence characteristic of the corresponding lanthanides (5D0 --> 7F0-4 (Eu3+) or the 5D4 --> 7F6-2 (Tb3+)) under UV excitation and a green luminescence of the chitosan shell under excitation in the visible region. Magnetic Resonance Imaging (MRI) efficiency, i.e. the nuclear relaxivity, measurements performed for Ln0.333+Gdx3+/[Mo(CN)8]3- nanoparticles show r1p and r2p relaxivities slightly higher than or comparable to the ones of the commercial paramagnetic compounds Gd

  3. Composition-Dependent Luminescent Properties of GeO2-Eu2O3-Ag Films

    NASA Astrophysics Data System (ADS)

    Bokshyts, Yu. V.

    2013-05-01

    An effect of Eu3+-precursor on the luminescent properties of GeO2-Eu2O3-Ag films was studied. This effect can be attributed to the different phase compositions of europium compounds after heat treatment and the change of structural parameters of the environment for europium ions.

  4. Luminescent and triboluminescent properties of europium(III) complex with cinnamic acid

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Mirochnik, A. G.; Nagornyi, I. G.

    2014-10-01

    An intensely emitting crystalline europium(III) complex with cinnamic acid [Eu(Cin)3] n and exhibiting triboluminescent properties is synthesized. It is established that the measured photo- and triboluminescence spectra are identical for the above polymeric non-centrosymmetric complex and are determined by the characteristic f-f luminescence of the europium(III) ion.

  5. Luminescence properties of mechanically milled and laser irradiated ZnO

    NASA Astrophysics Data System (ADS)

    Radoi, R.; Fernández, P.; Piqueras, J.; Wiggins, M. S.; Solis, J.

    2003-07-01

    The effect of mechanical milling on the luminescence properties of ZnO microcrystalline samples has been studied by means of cathodoluminescence in a scanning electron microscope. The samples consisted of pressed pellets of commercially available ZnO powder which were ball milled to investigate the possibility of nanocrystalline ZnO formation. Changes observed in the relative intensities of the characteristic ultraviolet and green band of ZnO are discussed in terms of defects generated during milling. The effect of nano- and picosecond pulsed laser irradiation on the particle size and luminescence of the milled samples has been also investigated.

  6. Luminescent and kinetic properties of the polystyrene composites based on BaF2 nanoparticles

    NASA Astrophysics Data System (ADS)

    Demkiv, T. M.; Halyatkin, O. O.; Vistovskyy, V. V.; Gektin, A. V.; Voloshinovskii, A. S.

    2016-02-01

    Luminescence-kinetic properties of polystyrene composites based on BaF2 nanoparticles were studied. The electron emission from the nanoparticles due to the photoelectric effect is the main luminescence excitation mechanism in the case of polystyrene composites loaded with small BaF2 nanoparticles (~20 nm). Scintillation pulse of polystyrene composites possesses only fast decay component with the time constant τ~2 ns, and its emission intensity considerably exceeds the one for pure polystyrene scintillator upon the X-ray excitations.

  7. Luminescence properties after X-ray irradiation for dosimetry

    NASA Astrophysics Data System (ADS)

    Hong, Duk-Geun; Kim, Myung-Jin

    2016-05-01

    To investigate the luminescence characteristics after exposure to X-ray radiation, we developed an independent, small X-ray irradiation system comprising a Varian VF-50J mini X-ray generator, a Pb collimator, a delay shutter, and an Al absorber. With this system, the apparent dose rate increased linearly to 0.8 Gy/s against the emission current for a 50 kV anode potential when the shutter was delayed for an initial 4 s and the Al absorber was 300 µm thick. In addition, an approximately 20 mm diameter sample area was irradiated homogeneously with X rays. Based on three-dimensional (3D) thermoluminescence (TL) spectra, the small X-ray irradiator was considered comparable to the conventional 90Sr/90Y beta source even though the TL intensity from beta irradiation was higher than that from X-ray irradiation. The single aliquot regenerative (SAR) growth curve for the small X-ray irradiator was identical to that for the beta source. Therefore, we concluded that the characteristics of the small X-ray irradiator and the conventional 90Sr/90Y beta source were similar and that X ray irradiation had the potential for being suitable for use in luminescence dosimetry.

  8. Luminescent properties of compounds of europium(III) with quinaldic acid and β-diketones

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.; Mirochnik, A. G.

    2015-12-01

    We have obtained luminescent complex compounds of europium(III) with quinaldic acid and β- diketones of composition Eu(Quin)2β-dic • H;2O, where Quin is the anion of quinaldic acid, and β-dic is the anion of acetylacetone (acac), benzoylacetone (bzac), or dibenzoylmethane (dbm). The spectral properties of the obtained compounds have been examined. The joint presence of quinaldic acid and β-diketone in the coordination sphere of europium(III) leads to a broadening of the absorption spectral range of the investigated complex compounds. We have found that the "anomalous" Stark structure of luminescence spectra and the luminescence quenching of complexes at 300 K are determined by the occurrence of a high-lying ligand-europium(III) charge-transfer state.

  9. Crystallization-Dependent Luminescence Properties of Ce:LuPO4.

    PubMed

    Sun, Congting; Li, Xingxing; Wang, Hao; Xue, Dongfeng

    2016-03-21

    The luminescence properties of Ce:LuPO4 depend on both the Ce(3+) center and the host lattice. In this article, we studied the dependence of the luminescence properties of Ce:LuPO4 on both the doping concentration of Ce(3+) and the size and morphology of the LuPO4 matrix at micro- and nanosize regimes. The crystalline behavior of Ce:LuPO4, including its size and shape, was investigated via precursor transformation crystallization. On the basis of this crystallization approach, Ce:LuPO4 hollow nanospheres, nanorods, and regular tetrahedrons were obtained. For micro- and nanostructured Ce:LuPO4, the surface-induced chemical bonding architecture can be effectively varied by controlling the size of the crystalline material and its geometry. Our experimental observations demonstrate that one-dimensional Ce:LuPO4 nanorods doped with 0.1 mol % Ce(3+) possess the best performance among the as-prepared samples. The significant anisotropy of Ce:LuPO4 nanorods can result in a larger specific surface area and enhanced luminescence properties. Moreover, the improved luminescence property of Ce:LuPO4 nanostructures can also be optimized by increasing the preferential anisotropic chemical bonding architecture to regulate the 5d level of Ce(3+). Our work also shows that the photoluminescence emission intensity of Ce:LuPO4 nanorods is increased as the surface area normal to their axial direction increases. From the standpoint of crystallization, the luminescence properties of Ce(3+) in nano- and microsize matrixes can be well-optimized by controlling the crystalline behavior of the host lattice under proper synthesis conditions. PMID:26863291

  10. Optically stimulated luminescence and thermoluminescence efficiencies for high-energy heavy charged particle irradiation in Al2O3:C

    NASA Technical Reports Server (NTRS)

    Yukihara, E. G.; Gaza, R.; McKeever, S. W. S.; Soares, C. G.

    2004-01-01

    The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The efficiencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four different HCPs beams (150 MeV/u 4He, 400 MeV/u 12C, 490 MeV/u 28Si, and 500 MeV/u 56Fe). The efficiencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the efficiency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C depends on the type of radiation, and, in principle, this can be used to extract information concerning the LET of an unknown radiation field. The response of the dosimeters to low-LET radiation was also investigated for doses in the range from about 1-1000 Gy. These data were used to explain the different efficiency values obtained for the different materials and techniques, as well as the LET dependence of the CW-OSL decay curve shape. c2003 Elsevier Ltd. All rights reserved.

  11. Thermally stimulated luminescence glow curve structure of β-irradiated CaB4O7:Dy.

    PubMed

    Akın, Aycan; Ekdal, Elçin; Arslanlar, Yasemin Tuncer; Ayvacıklı, Mehmet; Karalı, Turgay; Can, Nurdoğan

    2015-09-01

    Thermally stimulated luminescence glow curves of CaB4O7:Dy samples after β-irradiation showed glow peaks at ~335, 530 and 675 K, with a heating rate of 2 K/s. The main peak at 530 K was analyzed using the Tmax-Tstop method and was found to be composed of at least five overlapping glow peaks. A curve-fitting program was used to perform computerized glow curve deconvolution (CGCD) analysis of the complex peak of the dosimetric material of interest. The kinetic parameters, namely activation energy (E) and frequency factor (s), associated with the main glow peak of CaB4O7:Dy at 520 K were evaluated using peak shape (PS) and isothermal luminescence decay (ILD) methods. In addition, the kinetics was determined to be first order (b =1) by applying the additive dose method. The activation energies and frequency factors obtained using PS and ILD methods are calculated to be 0.72 and 0.72 eV and 8.76 × 10(5) and 1.44 × 10(6) /s, respectively. PMID:25428760

  12. Optically stimulated luminescence and thermoluminescence efficiencies for high-energy heavy charged particle irradiation in Al2O3:C.

    PubMed

    Yukihara, E G; Gaza, R; McKeever, S W S; Soares, C G

    2004-02-01

    The thermally and optically stimulated luminescence (TL and OSL) response to high energy heavy-charged particles (HCPs) was investigated for two types of Al2O3:C luminescence dosimeters. The OSL signal was measured in both continuous-wave (CW) and pulsed mode. The efficiencies of the HCPs at producing TL or OSL, relative to gamma radiation, were obtained using four different HCPs beams (150 MeV/u 4He, 400 MeV/u 12C, 490 MeV/u 28Si, and 500 MeV/u 56Fe). The efficiencies were determined as a function of the HCP linear energy transfer (LET). It was observed that the efficiency depends on the type of detector, measurement technique, and the choice of signal. Additionally, it is shown that the shape of the CW-OSL decay curve from Al2O3:C depends on the type of radiation, and, in principle, this can be used to extract information concerning the LET of an unknown radiation field. The response of the dosimeters to low-LET radiation was also investigated for doses in the range from about 1-1000 Gy. These data were used to explain the different efficiency values obtained for the different materials and techniques, as well as the LET dependence of the CW-OSL decay curve shape. PMID:14672096

  13. Luminescent properties of Mn2+ doped apatite nanophosphors

    NASA Astrophysics Data System (ADS)

    Ravindranadh, K.; Ravikumar, R. V. S. S. N.; Rao, M. C.

    2016-05-01

    Nanophosphors have been extensively investigated during the last decade due to their various high-performance application potential such as lamp industry, radiation dosimetry, X-ray imaging and colour display. The synthesis of inorganic nanophosphors using both ionizing radiation (IR) or UV light represents very promising technological field. Alkaline earth nanophosphors gathered a lot of attention in past decades because they are considered to be excellent host materials. Transition-metal oxides are well known luminescent emitters in the visible spectral region. Mn2+ doped calcium-lithium hydroxyapatite (CLHA) nanophosphors were prepared by mechanochemical synthesis. The prepared samples were characterized by photoluminescence studies. Photoluminescence spectra of Mn2+ doped CLHA nanophosphors exhibited green and strong orange emission bands at 534, 577 nm respectively under the excitation wavelength of 365 nm. The CIE chromaticity coordinates were also calculated from emission spectra for Mn2+ doped CLHA nanophosphors.

  14. Synthesis and luminescent properties of novel soluble quinacridones

    NASA Astrophysics Data System (ADS)

    Liu, Peihua; Chang, Chen-Pin; Tian, He

    2002-02-01

    Some novel 2, 5, 9, 12- tetra-substituted quinacridones were synthesized. The comparison of absorption spectra and fluorescence spectra of these soluble quinacridones between in solutions and in solid film indicated that the formation of intermolecular hydrogen bonds in the crystalline was obstructed by N-alkylation. These compounds have good solubility in common solvents such as dichloromethane, chloroform, acetone, DMF etc. The good solubility provides an opportunity for a higher doping concentration of the quinacridone fluorophore chromophore in the application of photoelectronic devices. The longer fluorescence lifetimes (ca. 20 ns) of these soluble quinacridones were measured by single-photon counting technique, which seems to be hopeful for the luminescence application. The EL device made with the soluble quinacridone show a luminance of 150 cd/m2 and injected current as high as 400 mA/ cm2 at 18 V.

  15. Dose response of commercially available optically stimulated luminescent detector, Al2O3:C for megavoltage photons and electrons.

    PubMed

    Kim, Dong Wook; Chung, Weon Kuu; Shin, Dong Oh; Yoon, Myonggeun; Hwang, Ui-Jung; Rah, Jeong-Eun; Jeong, Hojin; Lee, Sang Yeob; Shin, Dongho; Lee, Se Byeong; Park, Sung Yong

    2012-04-01

    This study examined the dose response of an optically stimulated luminescence dosemeter (OSLD) to megavoltage photon and electron beams. A nanoDot™ dosemeter was used to measure the dose response of the OSLD. Photons of 6-15 MV and electrons of 9-20 MeV were delivered by a Varian 21iX machine (Varian Medical System, Inc. Milpitas, CA, USA). The energy dependency was <1 %. For the 6-MV photons, the dose was linear until 200 cGy. The superficial dose measurements revealed photon irradiation to have an angular dependency. The nanoDot™ dosemeter has potential use as an in vivo dosimetric tool that is independent of the energy, has dose linearity and a rapid response compared with normal in vivo dosimetric tools, such as thermoluminescence detectors. However, the OSLD must be treated very carefully due to the high angular dependency of the photon beam. PMID:21636557

  16. Optically stimulated luminescence from Al 2O 3:C irradiated with 10-60 MeV protons

    NASA Astrophysics Data System (ADS)

    Edmund, J. M.; Andersen, C. E.; Greilich, S.; Sawakuchi, G. O.; Yukihara, E. G.; Jain, M.; Hajdas, W.; Mattsson, S.

    2007-09-01

    We investigated the potential use of Al 2O 3:C for medical proton dosimetry. Detector crystals coupled to fiber-optic cables were irradiated in proton beams with energies from 10 to 60 MeV. The key finding is that the initial intensity of the optically stimulated luminescence (OSL) signal is energy independent for small detectors (<0.5 mm) and relatively small doses (<0.3 Gy). This feature is related to the supralinearity of the detectors dose-response to low linear energy transfer (LET) radiation. The results show that our system can be used in medical proton dosimetry without LET-dependent correction factors in the dose and energy interval investigated.

  17. Luminescent Properties of Cerium Doped Potassium Iodide Single Crystals in Response to γ-irradiation.

    PubMed

    Bangaru, S; Saradha, K; Muralidharan, G

    2015-05-01

    Potassium iodide doped with cerium ions were prepared by Bridgemann Stockbarger technique and investigated by optical absorption, Photoluminescence(PL), Thermoluminescence(TL), Photostimulated Luminescence(PSL) and TL emission. The optical absorption measurement indicates that F and V centers are formed in the crystals during the γ-ray irradiation process. Optical absorption and Photoluminescence studies confirm the presence of cerium ions in the trivalent state. Spectral distribution under the Thermoluminescence Emission(TLE) and Optically Stimulated Luminescence(OSL) support the idea that the defect annihilation process to be due to thermal release of F-electron in KI:Ce(3+) crystals. Both Ce(3+) and Ce(2+) emissions were observed in the Thermoluminescence emission of the crystals. Thermoluminescence(TL) has been identified to be due to thermal release of electron produced during colouration process. PMID:25744528

  18. Surface contamination detection by means of near-infrared stimulation of thermal luminescence

    SciTech Connect

    Carrieri, Arthur H.; Roese, Erik S

    2006-02-01

    A method for remotely detecting liquid chemical contamination on terrestrial surfaces is presented. Concurrent to irradiation by an absorbing near-infrared beam, the subject soil medium liberates radiance called thermal luminescence (TL) comprising middle-infrared energies (numir) that is scanned interferometrically in beam duration tau. Cyclic states of absorption and emission by the contaminant surrogate are rendered from a sequential differential-spectrum measurement [deltaS(numir,tau)] of the scanned TL. Detection of chemical warfare agent simulant wetting soil is performed in this manner, for example, through pattern recognition of its unique, thermally dynamic, molecular vibration resonance bands on display in the deltaS(numir,tau) metric.

  19. The synthesis, structure, magnetic and luminescent properties of a new tetranuclear dysprosium (III) cluster

    SciTech Connect

    Chen, Yen-Han; Tsai, Yun-Fan; Lee, Gene-Hsian; Yang, En-Che

    2012-01-15

    The synthesis and characterization of [Dy{sub 4}(dhampH{sub 3}){sub 4}(NO{sub 3}){sub 2}](NO{sub 3}){sub 2} (1), a new tetranuclear dysprosium (III) complex, is described. The compound was characterized by its X-ray structure, magnetic properties as well as the luminescent spectra. The compound crystallizes in a P1-bar space group with a zig-zag linear form of geometry. The ac magnetic susceptibilities of the molecule indicate that it is a magnetic molecule with a slow magnetization relaxation. The molecule also exhibits an emission spectrum that was confirmed to be ligand based. These results indicate that this molecule has both a slow magnetization relaxation (that could be potentially a SMM) and luminescent properties. - Graphical Abstract: A new tetranuclear dysprosium (III) complex [Dy{sub 4}(dhampH{sub 3}){sub 4}(NO{sub 3}){sub 2}](NO{sub 3}){sub 2} is synthesized and reported in this paper. This molecule has luminescence and can potentially act as a SMM. Highlights: Black-Right-Pointing-Pointer A new designed ligand (dhampH{sub 5}) was syntheisized. Black-Right-Pointing-Pointer A new tetra-dysprosium cluster [Dy{sub 4}(dhampH{sub 3}){sub 4}(NO{sub 3}){sub 2}](NO{sub 3}){sub 2} was made. Black-Right-Pointing-Pointer Slow magnetization relaxation phenomenon was observed. Black-Right-Pointing-Pointer Ligand-based luminescence was observed.

  20. Highly luminescent Sm(III) complexes with intraligand charge-transfer sensitization and the effect of solvent polarity on their luminescent properties.

    PubMed

    Lo, Wai-Sum; Zhang, Junhui; Wong, Wing-Tak; Law, Ga-Lai

    2015-04-20

    Samarium complexes with the highest quantum yields to date have been synthesized, and their luminescence properties were studied in 12 solvents. Sensitization via a nontriplet intraligand charge-transfer pathway was also successfully demonstrated in solution states with good quantum yields. PMID:25835302

  1. Characterizations and luminescence properties of annealed porous silicon films

    NASA Astrophysics Data System (ADS)

    Songyan, Chen; Kashkarov, P. K.; Timoshenko, V. Yu; Baolin, Liu; Bingxi, Jiang

    2003-01-01

    Porous silicon (PS) samples were prepared by common electrochemical etching in HF-based electrolytes. Significantly increased current density (150 mA/cm 2) during anodization led to the accumulation of oxygen on the internal surface of the pores in the PS. Annealing of the samples was achieved in plasma of hydrogen for 15-30 min. During annealing at higher temperature (420-450°C) for 15 min or at lower temperature (250°C) for a longer time (30 min), the hydride coverage of the internal surface of the pores was replaced by a high-quality suboxide partially oxidized hydride layer or suboxide layer, as was shown by the evolution of infra-red absorption spectra due to annealing. Efficient violet and blue emissions were observed in these samples, which could be the result of the recombination of non-equilibrium carriers via an impurity center in the suboxide layer. In the sample that has a suboxide partially oxidized hydride layer, the luminescence mechanism needs a further investigation.

  2. Synthesis and optical properties of macrocyclic lanthanide(III) chelates as new reagents for luminescent biolabeling.

    PubMed

    Deslandes, Sébastien; Galaup, Chantal; Poole, Robert; Mestre-Voegtlé, Béatrice; Soldevila, Stéphanie; Leygue, Nadine; Bazin, Hervé; Lamarque, Laurent; Picard, Claude

    2012-11-14

    The convenient and efficient synthesis of two macrocyclic ligands (15- and 18-membered) based on a dipyrido-6,7,8,9-tetrahydrophenazine (dpqc) or 2,2':6',2''-terpyridine (tpy) heterocycle and a DTTA (diethylenetriaminetriacetic acid) skeleton is described. In these ligands the DTTA skeleton contains an additional extracyclic functionality (NH(2) group) suitable for covalent attachment to bioactive molecules. These octa- and nonadentate ligands form very stable and luminescent neutral lanthanide complexes in aqueous solutions at physiological pH. The corresponding Eu(III) and Tb(III) complexes are characterized by a maximum absorption wavelength compatible with nitrogen laser excitation (337 nm) and attractive lifetimes and quantum yields. Further introduction of a maleimide bioconjugatable handle in the Eu(III) complexes was investigated and a valuable luminescence brightness above 1500 dm(3) mol(-1) cm(-1) at 337 nm was obtained with the corresponding Eu(III) tpy-derivative. Finally, these two luminescent chelates were grafted onto thiol residues of a model antibody (Mab GSS11) without loss of their luminescent properties. PMID:23011114

  3. Structural, spectral-luminescent, and lasing properties of nanostructured Tm : CaF{sub 2} ceramics

    SciTech Connect

    Ryabochkina, P A; Lyapin, A A; Osiko, Vyacheslav V; Fedorov, Pavel P; Ushakov, S N; Kruglova, M V; Sakharov, N V; Garibin, E A; Gusev, P E; Krutov, M A

    2012-09-30

    The structure and the spectral-luminescent properties of CaF{sub 2} - TmF{sub 3} fluoride ceramics and single crystals are studied. AFM investigations revealed a layered nanostructure of grains, which was not observed in reference samples of single crystals. It is found that the spectral-luminescent properties of CaF{sub 2} - TmF{sub 3} ceramics and single crystals are similar. Lasing at the {sup 3}F{sub 4} {yields} {sup 3}H{sub 6} transition of Tm{sup 3+} ions in CaF{sub 2} - TmF{sub 3} ceramics (wavelength 1898 nm) under diode pimping is obtained for the first time. (laser applications and other topics in quantum electronics)

  4. Effects of Synthesis Process on Luminescence Properties and Structure of Mesoporous Carbon-Silica Nanocomposite

    NASA Astrophysics Data System (ADS)

    Sato, Koji; Ishikawa, Yukari; Ishii, Yosuke; Kawasaki, Shinji; Muto, Shunsuke; Yamamoto, Yuta

    2012-08-01

    The effects of hydrolysis and polycondensation reactions for synthesizing light-emitting mesoporous carbon-silica (MPCS) nanocomposite on the structure, chemical bonding state, and luminescence properties of MPCS were investigated by controlling the concentration (0.02 to 5 M) of HCl, which was used as a catalyst for hydrolysis and polycondensation. The progress of hydrolysis and polycondensation reactions provides a nanometer-order pore/wall structure and results in a strong light-emitting property. The pore/wall structure was obtained using HCl at concentrations of 0.2 M and higher, but it became disordered with increasing HCl concentration (2 and 5 M). The luminescence color of the MPCS nanocomposite can be changed from yellowish-white to bluish-white by changing the concentration of HCl.

  5. Lanthanide-organic complexes based on polyoxometalates: Solvent effect on the luminescence properties

    SciTech Connect

    Tang Qun; Liu Shuxia; Liang Dadong; Ma Fengji; Ren Guojian; Wei Feng; Yang Yuan; Li Congcong

    2012-06-15

    A series of lanthanide-organic complexes based on polyoxometalates (POMs) [Ln{sub 2}(DNBA){sub 4}(DMF){sub 8}][W{sub 6}O{sub 19}] (Ln=La(1), Ce(2), Sm(3), Eu(4), Gd(5); DNBA=3,5-dinitrobenzoate; DMF=N,N-dimethylformamide) has been synthesized. These complexes consist of [W{sub 6}O{sub 19}]{sup 2-} and dimeric [Ln{sub 2}(DNBA){sub 4}(DMF){sub 8}]{sup 2+} cations. The luminescence properties of 4 are measured in solid state and different solutions, respectively. Notably, the emission intensity increases gradually with the increase of solvent permittivity, and this solvent effect can be directly observed by electrospray mass spectrometry (ESI-MS). The analyses of ESI-MS show that the eight coordinated solvent DMF units of dimeric cation are active. They can move away from dimeric cations and exchange with solvent molecules. Although the POM anions escape from 3D supramolecular network, the dimeric state structure of [Ln{sub 2}(DNBA){sub 4}]{sup 2+} remains unchanged in solution. The conservation of red luminescence is attributed to the maintenance of the aggregated state structures of dimeric cations. - Graphical abstract: 3D POMs-based lanthanide-organic complexes performed the solvent effect on the luminescence property. The origin of such solvent effect can be understood and explained on the basis of the existence of coordinated active sites by the studies of ESI-MS. Highlights: Black-Right-Pointing-Pointer The solvent effect on the luminescence property of POMs-based lanthanide-organic complexes. Black-Right-Pointing-Pointer ESI-MS analyses illuminate the correlation between the structure and luminescence property. Black-Right-Pointing-Pointer The dimeric cations have eight active sites of solvent coordination. Black-Right-Pointing-Pointer The aggregated state structure of dimer cation remains unchanged in solution. Black-Right-Pointing-Pointer Luminescence associating with ESI-MS is a new method for investigating the interaction of complex and solvent.

  6. Electronic structure and spectral-luminescent properties of 1,2,4,6-tetrasubstituted pyridinium salts

    SciTech Connect

    Korunova, A.F.; Krainov, I.P.; Protsenko, E.G.

    1985-09-01

    The structure of the electronic excitation of 1,2,4,6-tetrasubstituted pyridinium salts was studied by quantum-chemical calculations carried out by the SCF PPP CI method, using excitation-localization numbers on the atoms and fragments, and interfragmentary charge transfer numbers. The nature of the absorption bands observed in the spectra and certain structural factors causing the spectral-luminescent properties were established.

  7. Effect of ultrasonic treatment on photoelectric and luminescent properties of ZnSe crystals

    SciTech Connect

    Zobov, E. M. Zobov, M. E.; Gabibov, F. S.; Kamilov, I. K.; Manyakhin, F. I.; Naimi, E. K.

    2008-03-15

    The results of the effect of ultrasonic treatment of ZnSe crystals on the structure of the energy spectrum of electronic states of centers with deep levels forming photoelectric and luminescent properties of this compound are presented. It is for the first time proved experimentally that the climb of edge dislocations under the effect of ultrasound leads to regrouping and generation of defects forming deep levels, which manifest themselves in phenomena of photosensitivity and radiative recombination.

  8. Optically Stimulated Luminescence Dating of Glacial Outwash Spanning the Last Glacial Cycle on the Western Olympic Peninsula, Washington, USA

    NASA Astrophysics Data System (ADS)

    Marshall, K. J.; Thackray, G. D.; Rittenour, T. M.

    2012-12-01

    Valley glaciers in the Olympic Mountains, Washington coalesced and advanced onto the Pacific coastal lowlands six times during Late Pleistocene time. With each advance, the valley glaciers constructed extensive landforms and thick stratigraphic sequences. Along the coast of the Olympic Peninsula, between the Hoh and Queets Rivers, wave-cut sea cliffs expose alternating sequences of outwash fans formed during periods of glacial advance and marine transgressive facies formed during periods of sea-level high stand. Previous work, encompassing geomorphic mapping of inland and coastal outcrops, stratigraphy, stratigraphic correlation, and radiocarbon dating, established a provisional glacial chronology for the Olympic coast, but was limited to the range of radiocarbon dating. Within the sea cliffs, three primary units of outwash were identified: the Hoh Oxbow (MIS 3), Lyman Rapids (MIS 4 or 5b), and Steamboat Creek outwash (MIS 6 or older). The outwash units are generally bounded by interglacial sea-level high stand sediments or interstadial terrestrial sediment. Our new investigations utilize detailed sedimentology and stratigraphy, mapping of geomorphic sequences, and optically stimulated luminescence (OSL) dating to extend and solidify the coastal glacial chronology. OSL methods provide a means to date outwash sequences directly and enable dating of previously undateable older sediments. The quartz in these sediments appears to be fully bleached and retains the luminescence signal. Furthermore, at two locations where both radiocarbon and OSL methods were applied on the same sediments, the ages are indistinguishable, indicating that OSL is reliable in these settings. Preliminary OSL ages from the outwash units indicate valley glacier advances on the Olympic Peninsula during Hoh Oxbow (MIS 3, ca. 30-50 ka), Lyman Rapids (MIS 4, ca. 50-80 ka), and Steamboat Creek (MIS 5d or older, >/= 105 ka). Additionally, general sediment fining up-section suggests a decrease in

  9. Luminescence Properties of Sm3+/Eu3+ Co-Doped ZnO Quantum Dots.

    PubMed

    Liu, Fengyi; Li, Hong; Hu, Yajing; Na, Jin; Mou, Yun; Yang, Kun; Ye, Zuhu; Li, Mingyue; Xie, Ya-Hong

    2016-04-01

    In order to improve luminescence properties of semiconductor ZnO quantum dots (QDs), Sm3+/Eu3+ co-doped ZnO QDs have been controllably synthesized by sol-gel method in this paper. ZnO QDs have a spherical shape with mean diameter at about 5-6 nm, which was characterized by high-resolution transmission electron microscopy (HRTEM). ZnO QDs have hexagonal wurtzite structure with parts of Sm3+ and Eu3+ incorporated into the lattice, which was demonstrated by X-ray Diffraction (XRD). Luminescence properties at room temperature (RT) of different amount of Sm3+ and 2 mol% Eu3+ doped ZnO QDs were examined in-depth by optical spectra. In contrast to the Pr3+/Eu3+ co-doped fluorescent performance researched in our previous study, the photoluminescence (PL) spectra indicates the unique luminescence properties of Sm3+/Eu3+ co-doped ZnO QDs. In addition, fluorescence lifetimes were obtained to illustrate the luminous mechanism. PMID:27451672

  10. Developments in optically stimulated luminescence and photo-transferred thermoluminescence dating of young sediments: Application to a 2000-year sequence of flood deposits

    NASA Astrophysics Data System (ADS)

    Murray, A. S.

    1996-02-01

    This paper demonstrates how optically stimulated luminescence (OSL) and photo-transferred thermoluminescence (PTTL) can be used to date young (0-2000 year-old) flood deposits on the bank of a major river in the Southern Tablelands of southeastern Australia. Quartz grains extracted from these deposits do not show a detectable dose-dependent sensitivity change following optical stimulation. This allows a recently proposed regeneration-based protocol (SARA) to be used to estimate the equivalent dose ( De) acquired since burial. For the oldest sample, a dependence of De on pre-heat temperature is removed by heating to at least 180 °C for 10 s before stimulation. Values of De are reported for six samples using both OSL and PTTL. Values ranged between 0.4 and 6.5 Gy, with overall uncertainties usually <7%; the values of De obtained using OSL and PTTL are in agreement. Dose rates are calculated from detailed analyses of environmental radionuclide concentrations, and the resulting luminescence dates range from 100 ± 13 to 1920 ± 130 years before present; the uncertainties include systematic effects. For two layers where there is age control by 14C dates, the luminescence dates are in good agreement. Unfortunately, the limitations of the 14C data preclude firm conclusions about the size of any effective age-residual at deposition for the luminescence samples, although this is likely to be <50-100 years. It is concluded that luminescence dating offers a considerable improvement over other techniques, including 14C, for recently transported fluvial sediments.

  11. Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties.

    PubMed

    Nadort, Annemarie; Zhao, Jiangbo; Goldys, Ewa M

    2016-07-01

    Upconversion photoluminescence is a nonlinear effect where multiple lower energy excitation photons produce higher energy emission photons. This fundamentally interesting process has many applications in biomedical imaging, light source and display technology, and solar energy harvesting. In this review we discuss the underlying physical principles and their modelling using rate equations. We discuss how the understanding of photophysical processes enabled a strategic influence over the optical properties of upconversion especially in rationally designed materials. We subsequently present an overview of recent experimental strategies to control and optimize the optical properties of upconversion nanoparticles, focussing on their emission spectral properties and brightness. PMID:26986473

  12. Lanthanide upconversion luminescence at the nanoscale: fundamentals and optical properties

    NASA Astrophysics Data System (ADS)

    Nadort, Annemarie; Zhao, Jiangbo; Goldys, Ewa M.

    2016-07-01

    Upconversion photoluminescence is a nonlinear effect where multiple lower energy excitation photons produce higher energy emission photons. This fundamentally interesting process has many applications in biomedical imaging, light source and display technology, and solar energy harvesting. In this review we discuss the underlying physical principles and their modelling using rate equations. We discuss how the understanding of photophysical processes enabled a strategic influence over the optical properties of upconversion especially in rationally designed materials. We subsequently present an overview of recent experimental strategies to control and optimize the optical properties of upconversion nanoparticles, focussing on their emission spectral properties and brightness.

  13. Optically stimulated luminescence age controls on late Pleistocene and Holocene coastal lithosomes, North Carolina, USA

    USGS Publications Warehouse

    Mallinson, D.; Burdette, K.; Mahan, S.; Brook, G.

    2008-01-01

    Luminescence ages from a variety of coastal features on the North Carolina Coastal Plain provide age control for shoreline formation and relative sea-level position during the late Pleistocene. A series of paleoshoreline ridges, dating to Marine Isotope Stage (MIS) 5a and MIS 3 have been defined. The Kitty Hawk beach ridges, on the modern Outer Banks, yield ages of 3 to 2??ka. Oxygen-isotope data are used to place these deposits in the context of global climate and sea-level change. The occurrence of MIS 5a and MIS 3 shorelines suggests that glacio-isostatic adjustment (GIA) of the study area is large (ca. 22 to 26??m), as suggested and modeled by other workers, and/or MIS 3 sea level was briefly higher than suggested by some coral reef studies. Correcting the shoreline elevations for GIA brings their elevation in line with other sea-level indicators. The age of the Kitty Hawk beach ridges places the Holocene shoreline well west of its present location at ca. 3 to 2??ka. The age of shoreline progradation is consistent with the ages of other beach ridge complexes in the southeast USA, suggesting some regionally contemporaneous forcing mechanism. ?? 2007 University of Washington.

  14. Investigation of radiation-induced free radicals and luminescence properties in fresh pomegranate fruits.

    PubMed

    Shahbaz, Hafiz M; Akram, Kashif; Ahn, Jae-Jun; Kwon, Joong-Ho

    2013-05-01

    Radiation-induced free radicals and luminescence properties were investigated in γ-irradiated (0-3 kGy) pomegranate ( Punica granatum L.) fruits. Photostimulated luminescence (PSL) analysis showed limited applicability, and only 3 kGy-irradiated pomegranates showed positive PSL values (>5000 PCs). Thermoluminescence (TL) glow curve features, such as intensity and the presence of maximum glow peak in radiation-specific temperature range (150-250 °C), provided definite proof of irradiation, and the TL ratios (TL1/TL2) also confirmed the reliability of TL results. Scanning electron microscopy energy dispersive X-ray (SEM-EDX) analysis of the separated minerals showed that feldspar and quartz minerals were responsible for the luminescence properties. Radiation-induced cellulose radicals were detected in the seeds and rinds by ESR analysis. The ESR results were better in freeze-dried samples than in alcohol-extracted ones. A positive correlation was found between the ESR and TL signal intensities and irradiation doses; however, the most promising detection of the irradiation status was possible through TL analysis. PMID:23565691

  15. Four new lanthanide-organic frameworks: selective luminescent sensing and magnetic properties.

    PubMed

    Ning, Yan; Wang, Lu; Yang, Guo-Ping; Wu, Yunlong; Bai, Nannan; Zhang, Wenyan; Wang, Yao-Yu

    2016-08-01

    Four new isostructural lanthanide-organic frameworks, [Ln(L)(H2O)2]·H2O·CH3CN (1-Ln) (Ln = Eu, Tb, Dy, and Gd), have been successfully synthesized via solvothermal reactions with a semi-rigid V-shaped multicarboxylate ligand 2-(2',4'-dicarboxylphenoxy) benzoic acid (H3L) and Ln(NO3)3·6H2O. 1-Ln shows 2D layer-by-layer frameworks with interlayer channels decorated by carboxylate groups. 1-Eu exhibits excellent luminescence properties, and therefore, is chosen as a probe for sensing different metal ions and anions. Consequently, 1-Eu displays high selectivity and sensitivity for Fe(3+) and Cr(6+) ions, simultaneously, through the luminescence quenching effect, and thus, should be an excellent candidate for probing these pollutant metal ions. In addition, antiferromagnetic exchange interactions also exist between the Dy(3+) ions in 1-Dy. PMID:27464998

  16. Synthesis and Luminescence Properties of Transparent Nanocrystalline GdF3:Tb Glass-Ceramic Scintillator.

    PubMed

    Lee, Gyuhyon; Savage, Nicholas; Wagner, Brent; Zhang, Yuelan; Jacobs, Benjamin; Menkara, Hisham; Summers, Christopher; Kang, Zhitao

    2014-03-01

    Transparent glass-ceramic containing rare-earth doped halide nanocrystals exhibits enhanced luminescence performance. In this study, a glass-ceramic with Tb doped gadolinium fluoride nanocrystals embedded in an aluminosilicate glass matrix is investigated for X-ray imaging applications. The nanocrystalline glass-ceramic scintillator was prepared by a melt-quench method followed by an anneal. The GdF3:Tb nanocrystals precipitated within the oxide glass matrix during the processing and their luminescence and scintillation properties were investigated. In this nanocomposite scintillator system, the incorporation of high atomic number Gd compound into the glass matrix increases the X-ray stopping power of the glass scintillator, and effective energy transfer between Gd(3+) and Tb(3+) ions in the nanocrystals enhances the scintillation efficiency. PMID:24610960

  17. Synthesis and Luminescence Properties of Transparent Nanocrystalline GdF3:Tb Glass-Ceramic Scintillator

    PubMed Central

    Lee, Gyuhyon; Savage, Nicholas; Wagner, Brent; Zhang, Yuelan; Jacobs, Benjamin; Menkara, Hisham; Summers, Christopher; Kang, Zhitao

    2014-01-01

    Transparent glass-ceramic containing rare-earth doped halide nanocrystals exhibits enhanced luminescence performance. In this study, a glass-ceramic with Tb doped gadolinium fluoride nanocrystals embedded in an aluminosilicate glass matrix is investigated for X-ray imaging applications. The nanocrystalline glass-ceramic scintillator was prepared by a melt-quench method followed by an anneal. The GdF3:Tb nanocrystals precipitated within the oxide glass matrix during the processing and their luminescence and scintillation properties were investigated. In this nanocomposite scintillator system, the incorporation of high atomic number Gd compound into the glass matrix increases the X-ray stopping power of the glass scintillator, and effective energy transfer between Gd3+ and Tb3+ ions in the nanocrystals enhances the scintillation efficiency. PMID:24610960

  18. Synthesis and Thermally Stimulated Luminescence of Polycrystalline Sr{sub 1-x}Eu{sub x}B{sub 4}O{sub 7}

    SciTech Connect

    Dubovik, M.F.; Korshikova, T.I.; Parkhomenko, S.V.; Tolmachev, A.V.

    2005-12-15

    Specific features of the solid-phase synthesis of Sr{sub 1-x}Eu{sub x}B{sub 4}O{sub 7} (x 0-0.15) in air are studied. The photo- and thermally stimulated luminescence of Sr{sub 1-x}Eu{sub x}B{sub 4}O{sub 7} is investigated in the range of Eu content 0.01 < x < 0.15. The main energy parameters of traps are determined. It is shown that the peak of thermally stimulated luminescence at T = 380 K can be related to the decomposition and radiative relaxation of the [Eu{sup 3+}{sub Sr{sup 2}{sup +}} F{sup +} center] pair.

  19. Time-evolving photo-induced changes of luminescent and spectral properties of PbS quantum dots sols

    NASA Astrophysics Data System (ADS)

    Evstropiev, S. K.; Kislyakov, I. M.; Bagrov, I. V.; Belousova, I. M.; Kiselev, V. M.

    2016-05-01

    Light irradiation influence on spectral and luminescent properties of PbS sol, stabilized by high-molecular polyvinylpyrrolidone, was studied as a time-evolving process. Uniform and stable for at least three months PbS/PVP suspensions were obtained with an average quantum dots size of 4 nm. Photoluminescent spectra of the suspensions showed wide intensive emission at 1000-1400 nm upon excitation by visible light. Luminescence intensities of all the suspensions demonstrate nonlinear dependences on the exciting radiation intensity. Experimental results show that light irradiation during luminescence measurements even with low excitation power density can significantly change luminescent and spectral properties of PbS quantum dots. The dependences found can be useful in preparation of a variety of quantum dots-containing photonics materials.

  20. Ti:Sapphire micro-structures by femtosecond laser inscription: Guiding and luminescence properties

    NASA Astrophysics Data System (ADS)

    Ren, Yingying; Jiao, Yang; Vázquez de Aldana, Javier R.; Chen, Feng

    2016-08-01

    We report on the fabrication of buried cladding waveguides with different diameters in a Ti:Sapphire crystal by femtosecond laser inscription. The propagation properties are studied, showing that the cladding waveguides could support near- to mid-infrared waveguiding at both TE and TM polarizations. Confocal micro-photoluminescence experiments reveal that the original fluorescence properties in the waveguide region are very well preserved, while it suffers from a strong quenching at the centers of laser induced filaments. Broadband waveguide fluorescence emissions with high efficiency are realized, indicating the application of the cladding waveguides in Ti:Sapphire as compact broadband luminescence sources in biomedical fields.

  1. Near-real-time radiotherapy dosimetry using optically stimulated luminescence of Al{sub 2}O{sub 3}:C: Mathematical models and preliminary results

    SciTech Connect

    Gaza, R.; McKeever, S.W.S.; Akselrod, M.S.

    2005-04-01

    In this paper we report investigations aimed toward applying optically stimulated luminescence (OSL) of Al{sub 2}O{sub 3}:C for near-real-time medical dosimetry, especially in radiotherapy. The classical mathematical model normally used for the description of OSL phenomena was expanded to predict the behavior of the luminescence signal in the case when the OSL sample is simultaneously irradiated and optically stimulated. The predictions obtained were used to develop different measurement approaches and correction algorithms for the luminescence signals, thus enabling dose estimation from OSL during rather then after the irradiation procedure. Radiation probes with diameters of less than 1 mm, suitable for the envisioned in-vivo measurements were constructed by attaching small Al{sub 2}O{sub 3}:C crystals to optical fiber cables. The OSL fiber probes and a purpose-built, portable OSL stimulation and readout system were used to measure doses at speeds up to 1 data point every 3s, under irradiation at dose rates of the same order of magnitude as those found in conventional radiotherapy techniques. The corrected OSL signal was found to be proportional to the absorbed dose, and accurately followed sudden transitions in the irradiation dose rate.

  2. Optically stimulated luminescence in vivo dosimetry for radiotherapy: physical characterization and clinical measurements in (60)Co beams.

    PubMed

    Mrčela, I; Bokulić, T; Izewska, J; Budanec, M; Fröbe, A; Kusić, Z

    2011-09-21

    A commercial optically stimulated luminescence (OSL) dosimetry system was investigated for in vivo dosimetry in radiation therapy. Dosimetric characteristics of InLight dot dosimeters and a microStar reader (Landauer Inc.) were tested in (60)Co beams. The reading uncertainty of a single dosimeter was 0.6%. The reproducibility of a set of dosimeters after a single irradiation was 1.6%, while in repeated irradiations of the same dosimeters it was found to be 3.5%. When OSL dosimeters were optically bleached between exposures, the reproducibility of repeated measurements improved to 1.0%. Dosimeters were calibrated for the entrance dose measurements and a full set of correction factors was determined. A pilot patient study that followed phantom validation testing included more than 100 measured fields with a mean relative difference of the measured entrance dose from the expected dose of 0.8% and the standard deviation of 2.5%. In conclusion, these results demonstrate that OSL dot dosimeters represent a valid alternative to already established in vivo dosimetry systems. PMID:21873767

  3. Optically stimulated luminescence dating of late Holocene raised strandplain sequences adjacent to Lakes Michigan and Superior, Upper Peninsula, Michigan, USA

    USGS Publications Warehouse

    Argyilan, Erin P.; Forman, Steven L.; Johnston, John W.; Wilcox, Douglas A.

    2005-01-01

    This study evaluates the accuracy of optically stimulated luminescence to date well-preserved strandline sequences at Manistique/Thompson bay (Lake Michigan), and Tahquamenon and Grand Traverse Bays (Lake Superior) that span the past ∼4500 yr. The single aliquot regeneration (SAR) method is applied to produce absolute ages for littoral and eolian sediments. SAR ages are compared against AMS and conventional 14C ages on swale organics. Modern littoral and eolian sediments yield SAR ages 14C ages on swale organics. Significant variability in 14C ages >2000 cal yr B.P. complicates comparison to SAR ages at all sites. However, a SAR age of 4280 ± 390 yr (UIC913) on ridge77 at Tahquamenon Bay is consistent with regional regression from the high lake level of the Nipissing II phase ca. 4500 cal yr B.P. SAR ages indicate a decrease in ridge formation rate after ∼1500 yr ago, likely reflecting separation of Lake Superior from lakes Huron and Michigan. This study shows that SAR is a credible alternative to 14C methods for dating littoral and eolian landforms in Great Lakes and other coastal strandplains where 14C methods prove problematic.

  4. Feasibility study of an optically-stimulated luminescent nanodot dosimeter (OSLnD) in high-energy photon beams

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Young; Park, Sung-Kwang; Kim, Yon-Lae; Suh, Tae-Suk; Shin, Jung-Wook; Oh, Kyoung-Min; Nam, Sang-Hee; Kim, Jong-Eon; Min, Byung-In; Jo, Sun-Mi; Oh, Won-Young

    2014-10-01

    In-vivo dosimetry is essential to verify the position and the intensity of the radiation therapy, such as cranio-spinal irradiation (CSI) and total body irradiation (TBI). Various kinds of devices, such as a thermo-luminesence dosimeters (TLDs), metal-oxide semiconductor field effect transistors (MOSFETs), semiconductor diodes, and gafchromic films, are used in in-vivo dosimetry, and these have their respective pros and cons. An optically-stimulated luminescent nanodot dosimeter (OSLnD) made of Al2O3: C was developed to measure the radiation dose during diagnostics, but it is now used for clinical purposes. In this study, the characteristics of the OSLnD, such as its dose rate dependency, dose linearity, angular dependency, and field junction, were investigated under a 6 MV X-ray beam. The OSLnD showed a linear response at doses from 20 to 300 cGy in the dose linearity test. Also, the dose rate dependency was shown to be less than 3%, angular dependency to be less than 2%. The experimental results proved the OSLnD to be useful for measurements of the external dose and for intensity modulated radiotherapy (IMRT) in clinical radiotherapy.

  5. Luminescent properties of rare earth ions in one-dimensional oxide nanowires.

    PubMed

    Song, Hongwei; Yu, Lixin; Yang, LinMei; Lu, Shaozhe

    2005-09-01

    Rare-earth doped one-dimensional oxide nanowires including LaPO4, La2O3, and Gd2O3 were synthesized by the hydrothermal method. Their luminescent properties including local environments, electronic transitions, energy transfer, and frequency up-conversion luminescence processes were systematically studied. In LaPO4:Eu and La2O3:Eu nanowires, different symmetry sites of Eu3+ ions were identified, which obviously differed from those of the corresponding micrometer-sized particles. This was attributed to crystal field degeneration in the fringe along the length axis. In LaPO4:Eu nanowires, the electronic transition rate of 5D1-sigmaJ7FJ increased approximately 2 times over that of the zero-dimensional nanoparticles and micrometer-sized particles, which was related to the variation of dipole field induced by shape anisotropy. Considering the nonradiative relaxations, meanwhile, the luminescent quantum efficiency for 5D1-sigmaJ7FJ transitions of Eu3+ in nanowires increased 100% over that in nanoparticles and 20% over that in micrometer particles. In Gd2O3:Eu3+, LaPO4:Ce3+, and LaPO4:Tb3+ nanowires and micrometer-sized particles, the electronic transition rate of rare earths had only a little variation. In LaPO4:Ce3+/Tb3+ nanowires, the energy transfer rate of Ce3+--> Tb3+ decreased 3 times compared to that in micrometer rods. Despite this, the brightness for the 5D4-7F5 green emissions of Tb3+ increased several times due to decreased energy transfer from the excited states higher than 5D4 to some defect levels. In Gd2O3:Er3+/Yb3+ nanocrystals, as the shape varied from nanopapers to nanowires, the relative intensity of up-conversion luminescence of 2H(11/2)/4S(3/2)-4I(15/2) and 4F(9/2)-4I(15/2) to the infrared down-conversion luminescence of 4I(13/2)-4I(15/2) increased remarkably, indicating efficient up-conversion luminescence. Our present results indicate that rare-earth-doped oxide nanowires is a type of new and efficient phosphors. PMID:16193968

  6. Luminescent properties of Er and Si co-implanted silicates

    NASA Astrophysics Data System (ADS)

    Pellegrino, P.; Garrido, B.; Lebour, Y.; Moreno, J. A.; Garcia, C.; Morante, J. R.; Bettotti, P.; Pavesi, L.; Prassas, M.

    2005-02-01

    An extensive research for optical active materials at 1540 nm is currently being carried out, on the steam of the strong need for optoelectronic devices which can be integrated with the mainstream Si technology. The formation of silica films doped with Er and Si clusters has been shown as one of the promising approaches. We explored the emission properties of different silicate glasses co-implanted with silicon and Er ions to various doses. As starting materials we used soda-lime and aluminium silicates, glasses which show a larger optical bandwidth than silica at 1540 nm. A Si multi-implantation scheme has been adopted for a planar profile. The best conditions to precipitate Si and activate the Er atoms have been investigated. Optimal annealing temperatures have been found around 500 °C, depending on the particular composition of the original glass substrate. The structural analysis of the resulting structures ensures that the best emission properties are the ones for which a phase separation between the implanted Si and the matrix occurs, even without the formation of crystalline aggregates. A comprehensive study of the emission properties is given as a function of the matrix characteristics, Si and Er content, excitation wavelength and power density. It is shown an increase of the emission enhancement of the Er atoms due to the presence of Si cluster when increasing the excitation power. Modelling of the interaction between the absorbing Si nanoprecipitates and the emitting Er atoms has been carried out, in order to estimate the relevant physical parameters which describe the PL process.

  7. Luminescent CdTe and CdSe semiconductor nanocrystals: preparation, optical properties and applications.

    PubMed

    Wang, Ying

    2008-03-01

    The novel optical and electrical properties of luminescent semiconductor nanocrystals are appealing for ultrasensitive multiplexing and multicolor applications in a variety of fields, such as biotechnology, nanoscale electronics, and opto-electronics. Luminescent CdSe and CdTe nanocrystals are archetypes for this dynamic research area and have gained interest from diverse research communities. In this review, we first describe the advances in preparation of size- and shape-controlled CdSe and CdTe semiconductor nanocrystals with the organometallic approach. This article gives particular focus to water soluble nanocrystals due to the increasing interest of using semiconductor nanocrystals for biological applications. Post-synthetic methods to obtain water solubility, the direct synthesis routes in aqueous medium, and the strategies to improve the photoluminescence efficiency in both organic and aqueous phase are discussed. The shape evolution in aqueous medium via self-organization of preformed nanoparticles is a versatile and powerful method for production of nanocrystals with different geometries, and some recent advances in this field are presented with a qualitative discussion on the mechanism. Some examples of CdSe and CdTe nanocrystals that have been applied successfully to problems in biosensing and bioimaging are introduced, which may profoundly impact biological and biomedical research. Finally we present the research on the use of luminescent semiconductor nanocrystals for construction of light emitting diodes, solar cells, and chemical sensors, which demonstrate that they are promising building blocks for next generation electronics. PMID:18468108

  8. Influence of peculiarities of electronic excitation relaxation on luminescent properties of MgWO4

    NASA Astrophysics Data System (ADS)

    Krutyak, N. R.; Spassky, D. A.; Tupitsyna, I. A.; Dubovik, A. M.

    2016-07-01

    Luminescent properties of magnesium tungstate monocrystals grown by two different methods are studied. Only the exciton luminescence of these crystals themselves is observed. Temperature dependence of the low-energy range in the luminescence excitation spectra is described by the Urbach rule. Slope coefficient σ0 = 0.74 obtained from this dependence implies autolocalization of the excitons in MgWO4. The processes of electronic excitations relaxation are considered depending on the structure of valence band in MgWO4 and in other wolframites, ZnWO4 and CdWO4. In contrast to ZnWO4 and CdWO4, the d-states of the cation do not participate in formation of the MgWO4 valence band. Using the excitation spectra measured in the range of the fundamental absorption (4-20 eV), it is shown that this difference manifests itself in relaxation of electronic excitations and may be the cause of the relatively low light yield of MgWO4.

  9. Luminescence properties of Cr-doped silica sol gel glasses

    NASA Astrophysics Data System (ADS)

    Strek, Wieslaw; Lukowiak, Edward; Deren, Przemyslaw J.; Maruszewski, K.; Trabjerg, Ib; Koepke, Czeslaw; Malashkevich, G. E.; Gaishun, Vladimir E.

    1997-11-01

    The emission of Cr-doped silica glass obtained by the sol- gel method is characterized by an orange broad band with a maximum at 610 nm. Its nature is examined by the absorption, excited state absorption, emission, excitation and lifetime measurements over a wide range of temperature and for different concentration of Cr ions. Our measurement show that in spite of fact that the absorption properties of Cr- doped silica sol-gel glass are predominantly associated with Cr4+ centers, the observed in visible range emission can be assigned neither to Cr3+ nor to Cr4+ ions. The discussion of the nature of observed emission was carried out for all possible valencies of the Cr ions. In conclusion is suggested that it may be ascribed to the transitions on the monovalent Cr1+ ion. The reducing agents occurring during the sol-gel process and leading to lowering the Cr valency are discussed.

  10. Study of luminescence, color and paramagnetic centers properties of albite

    NASA Astrophysics Data System (ADS)

    Cano, Nilo F.; dos Santos, Lara H. E.; Chubaci, Jose F. D.; Watanabe, Shigueo

    2015-02-01

    A sample of natural albite, NaAlSi3O8, from the state of Minas Gerais, Brazil, has been investigated. The mineral is a solid solution of K-feldspar (4600 ppm - K) and Ca-feldspar (1100 ppm - Ca). The TL spectra of natural and the pre-annealed at high temperature albite presented a very intense band around 275 nm and weaker bands around 400 and 560 nm. Other TL properties have been investigated through monochromatic (275 nm and 400 nm) glow curves. The EPR spectrum measured at low temperature (77 K) shows the typical 11 lines signal due to Al-O--Al center superposed on Fe3+ signal around g = 2.0. The EPR spectra above 260 K show only g = 2.0 signal due to Fe3+ ions.

  11. Persistent luminescence and photocatalytic properties of Ga2O3:Cr3+,Zn2+ phosphors

    NASA Astrophysics Data System (ADS)

    Wang, Yinhai; Xu, Ke; Li, Darong; Zhao, Hui; Hu, Zhengfa

    2014-09-01

    Ga2O3:Cr3+0.01, Zn2+0.005 and Ga2O3:Cr3+0.01 phosphors were synthesized by the high temperature solid state reaction. The emission and excitation spectra, persistent luminescence decay curve, thermoluminescence curve and photocatalytic properties were measured. The emission and excitation spectra indicate that the Zn2+ doping has no effect on photoluminescent properties of Ga2O3:Cr3+0.01. The red persistent luminescence of Ga2O3:Cr3+0.01, Zn2+0.005 could be observed for 20 min by naked eye. The thermoluminescence (TL) curve shows that a suitable trap was introduced into the Ga2O3:Cr3+ host by Zn2+ doping. The photocatalytic activity toward rhodamineB (RhB) was obtained to evaluate photocatalytic properties by Zn2+ doping. The results indicate that the Zn2+ doping could improve the photocatalytic properties of Ga2O3:Cr3+0.01 phosphors. It was considered that the new traps play an important role for trapping the electrons or holes to decrease the combination of the electrons and holes producing by the light irradiation and increase the photocatalytic activity.

  12. Research on the spectral properties of luminescent carbon dots

    NASA Astrophysics Data System (ADS)

    Lin, Li-ping; Wang, Xin-Xing; Lin, Shao-Qin; Zhang, Li-Hong; Lin, Chang-Qing; Li, Zhi-Ming; Liu, Jia-Ming

    This paper is trying to research the developing status of carbon dots (CDs), and the results show that the simple, rapid and high yield synthetic methods for CDs and the application of CDs in biological science and analysis field will certainly become an inevitable development trend in the future. The CDs obtained by microwave possess excellent optical properties including UV-Vis absorption, fluorescence and room temperature phosphorescence. Under the conditions of 30 °C and 10 min, the fluorescence signal (F) of CDs not only could be enhanced by hexadecyltrimethylammonium bromide (CTAB), Triton X-100, Na2S, Na2C2O4 and NH3.H2O, but also could be quenched by sodium dodecyl sulfate, KBrO3, K2S2O8, NaIO4, ascorbic acid, NaBH4, HNO3, HCl, H2SO4, CH3COOH and most metal ions, with the λemmax blue or red shifting in varying degrees, indicating the potential values of CDs in analytical application. Besides, the sensitive response of F to pH showed the promise of developing a new pH sensor with CDs.

  13. Studies of LSO:Tb radio-luminescence properties using white beam hard X-ray synchrotron irradiation

    NASA Astrophysics Data System (ADS)

    Cecilia, A.; Rack, A.; Pelliccia, D.; Douissard, P.-A.; Martin, T.; Couchaud, M.; Dupré, K.; Baumbach, T.

    A radio-luminescence set-up was installed at the synchrotron light source ANKA to characterise scintillators under the high X-ray photon flux density of white beam synchrotron radiation. The system allows for investigating the radio-luminescence spectrum of the material under study as well as analysing in situ changes of its scintillation behaviour (e.g. under heat load and/or intensive ionising radiation). In this work we applied the radio-luminescence set-up for investigating the radiation damage effects on the luminescence properties of a new kind of thin single crystal scintillator for high resolution X-ray imaging based on a layer of modified Lu2SiO5 grown by liquid phase epitaxy on a dedicated substrate within the framework of an EC project (SCINTAX).

  14. Assembly-Induced Enhancement of Cu Nanoclusters Luminescence with Mechanochromic Property.

    PubMed

    Wu, Zhennan; Liu, Jiale; Gao, Yang; Liu, Huiwen; Li, Tingting; Zou, Haoyang; Wang, Zhigang; Zhang, Kai; Wang, Yue; Zhang, Hao; Yang, Bai

    2015-10-14

    Metal nanoclusters (NCs) as a new class of phosphors have attracted a great deal of interest owing to their unique electronic structure and subsequently molecule-like optical properties. However, limited successes have been achieved in producing the NCs with excellent luminescent performance. In this paper, we demonstrate the significant luminescence intensity enhancement of 1-dodecanethiol (DT)-capped Cu NCs via self-assembly strategy. By forming compact and ordered assemblies, the original nonluminescent Cu NCs exhibit strong emission. The flexibility of self-assembly allows to further control the polymorphism of Cu NCs assemblies, and hence the emission properties. Comparative structural and optical analysis of the polymorphic NCs assemblies permits to establish a relationship between the compactness of assemblies and the emission. First, high compactness reinforces the cuprophilic Cu(I)···Cu(I) interaction of inter- and intra-NCs, and meanwhile, suppresses intramolecular vibration and rotation of the capping ligand of DT, thus enhancing the emission intensity of Cu NCs. Second, as to the emission energy that depends on the distance of Cu(I)···Cu(I), the improved compactness increases average Cu(I)···Cu(I) distance by inducing additional inter-NCs cuprophilic interaction, and therewith leads to the blue shift of NCs emission. Attributing to the assembly mediated structural polymorphism, the NCs assemblies exhibit distinct mechanochromic and thermochromic luminescent properties. Metal NCs-based white light-emitting diodes are further fabricated by employing the NCs assemblies with blue-green, yellow, and red emissions as phosphors. PMID:26397821

  15. Morphological, luminescence and structural properties of nanocrystalline silicon thin films

    SciTech Connect

    Ali, Atif Mossad; Kobayashi, Hikaru; Inokuma, Takao; Al-Hajry, Ali

    2013-03-15

    Highlights: ► The PL spectra showed two stronger peaks and one weaker peak. ► The PL peak energies and optical band-gap values were found higher than 1.12 eV. ► The structural change from an amorphous to nanocrystalline with increasing [SiH{sub 4}]. - Abstract: Nanocrystalline silicon (nc-Si) thin films deposited by plasma-enhanced chemical vapor deposition at various silane flow rates ([SiH{sub 4}]) are studied. The characterization of these films by high-resolution transmission electron microscopy, Raman spectroscopy and X-ray diffraction reveals that no film and very thin film is deposited at [SiH{sub 4}] = 0.0 and 0.1 sccm, respectively. In addition, the structural change from an amorphous to a nanocrystalline phase occurs at around [SiH{sub 4}] = 0.2 sccm. In this study, the importance of arriving species at surfaces and precursors is clearly demonstrated by the effect of a small addition of SiH{sub 4} on the frequency and width of a Raman peak and the structure of the grown film. The infrared spectroscopic analysis shows no hydrogen incorporation in the nc-Si film deposited at the low value of [SiH{sub 4}]. However, the intensity of the peak around 2100 cm{sup −1} due to SiH decreases with increasing [SiH{sub 4}]. All fabricated films give photoluminescence in the range between 1.7 and 2.4 eV at room temperature, indicating enlargement of the band-gap energy. The presence of very small crystallites leads to the appearance of quantum confinement effects. The variations of the photoluminescence energy and spectral width are well correlated with the structural properties of the films such as crystallite size, crystalline volume fraction, and the density of Si-H bonds.

  16. Spectral and temporal luminescent properties of Eu(III) in humic substance solutions from different origins

    NASA Astrophysics Data System (ADS)

    Brevet, Julien; Claret, Francis; Reiller, Pascal E.

    2009-10-01

    Although a high heterogeneity of composition is awaited for humic substances, their complexation properties do not seem to greatly depend on their origins. The information on the difference in the structure of these complexes is scarce. To participate in the filling of this lack, a study of the spectral and temporal evolution of the Eu(III) luminescence implied in humic substance (HS) complexes is presented. Seven different extracts, namely Suwannee River fulvic acid (SRFA) and humic acid (SRHA), and Leonardite HA (LHA) from the International Humic Substances Society (USA), humic acid from Gorleben (GohyHA), and from the Kleiner Kranichsee bog (KFA, KHA) from Germany, and purified commercial Aldrich HA (PAHA), were made to contact with Eu(III). Eu(III)-HS time-resolved luminescence properties were compared with aqueous Eu 3+ at pH 5. Using an excitation wavelength of 394 nm, the typical bi-exponential luminescence decay for Eu(III)-HS complexes is common to all the samples. The components τ1 and τ2 are in the same order of magnitude for all the samples, i.e., 40 ≤ τ1 (μs) ≤ 60, and 145 ≤ τ2 (μs) ≤ 190, but significantly different. It is shown that different spectra are obtained from the different groups of samples. Terrestrial extract on the one hand, i.e. LHA/GohyHA, plus PAHA, and purely aquatic extracts on the other hand, i.e., SRFA/SRHA/KFA/KHA, induce inner coherent luminescent properties of Eu(III) within each group. The 5D 0 → 7F 2 transition exhibits the most striking differences. A slight blue shift is observed compared to aqueous Eu 3+ ( λmax = 615.4 nm), and the humic samples share almost the same λmax ≈ 614.5 nm. The main differences between the samples reside in a shoulder around λ ≈ 612.5 nm, modelled by a mixed Gaussian-Lorentzian band around λ ≈ 612 nm. SRFA shows the most intense shoulder with an intensity ratio of I612.5/ I614.7 = 1.1, KFA/KHA/SRHA share almost the same ratio I612.5/ I614.7 = 1.2-1.3, whilst the LHA

  17. Spectral and temporal luminescent properties of Eu(III) in humic substance solutions from different origins.

    PubMed

    Brevet, Julien; Claret, Francis; Reiller, Pascal E

    2009-10-01

    Although a high heterogeneity of composition is awaited for humic substances, their complexation properties do not seem to greatly depend on their origins. The information on the difference in the structure of these complexes is scarce. To participate in the filling of this lack, a study of the spectral and temporal evolution of the Eu(III) luminescence implied in humic substance (HS) complexes is presented. Seven different extracts, namely Suwannee River fulvic acid (SRFA) and humic acid (SRHA), and Leonardite HA (LHA) from the International Humic Substances Society (USA), humic acid from Gorleben (GohyHA), and from the Kleiner Kranichsee bog (KFA, KHA) from Germany, and purified commercial Aldrich HA (PAHA), were made to contact with Eu(III). Eu(III)-HS time-resolved luminescence properties were compared with aqueous Eu(3+) at pH 5. Using an excitation wavelength of 394 nm, the typical bi-exponential luminescence decay for Eu(III)-HS complexes is common to all the samples. The components tau(1) and tau(2) are in the same order of magnitude for all the samples, i.e., 40 luminescent properties of Eu(III) within each group. The (5)D(0) --> (7)F(2) transition exhibits the most striking differences. A slight blue shift is observed compared to aqueous Eu(3+) (lambda(max) = 615.4 nm), and the humic samples share almost the same lambda(max) approximately 614.5 nm. The main differences between the samples reside in a shoulder around lambda approximately 612.5 nm, modelled by a mixed Gaussian-Lorentzian band around lambda approximately 612 nm. SRFA shows the most intense shoulder with an intensity ratio of I(612.5)/I(614.7) = 1.1, KFA

  18. Site characterization using a portable optically stimulated luminescence reader: delineating disrupted stratigraphy in Holocene eolian deposits on the Canadian Great Plains

    NASA Astrophysics Data System (ADS)

    Munyikwa, K.; Gilliland, K.; Gibson, T.; Plumb, E.

    2012-12-01

    The use of portable optically stimulated luminescence (POSL) readers to elucidate on complex depositional sequences has been demonstrated in a number of recent studies. POSL readers are robust versions of the traditional lab-bound luminescence readers and they can be used in the field, allowing for rapid decisions to be made when collecting samples for dating. Furthermore, in contrast with lab-bound readers, POSL readers can perform measurements on bulk samples, negating the need to carry out time-intensive mineralogical separations. The POSL reader is equipped with both infra-red and blue light (OSL) stimulating sources such that signal separation during measurement can be carried out by selectively exciting feldspar using the IR source (IRSL) after which a quartz dominant signal is obtained from the same sample using post-IR blue OSL. The signals obtained are then plotted to give luminescence profiles that depict the variation of the luminescence signal with depth. Signal intensities depend on mineralogical concentrations, grain luminescence sensitivities, dose rates as well as on burial ages of the grains. Where all these variables, apart from the burial age, are held constant up the depositional sequence the luminescence profile serves as a proxy for the chronostratigraphy. As a contribution to a growing archive of studies that have employed POSL readers to unravel complex depositional sequences, this study uses a POSL system developed by the Scottish Universities Environmental Research Centre to characterize the stratigraphy at an archaeological site that lies next to an oilfield plant located on a Holocene fossil dune landscape in southern Alberta, Canada. Oilfield activity was initiated at the site several decades ago and it involved the laying of pipelines below ground which disturbed considerable archaeological deposits. Subsequent work led to the discovery of the archeological site which was previously occupied by ancestral indigenous peoples at various

  19. SU-E-T-600: In Vivo Dosimetry for Total Body and Total Marrow Irradiations with Optically Stimulated Luminescence Dosimeters

    SciTech Connect

    Niedbala, M; Save, C; Cygler, J

    2014-06-01

    Purpose: To evaluate the feasibility of using optically stimulated luminescence dosimeters (OSLDs) for in-vivo dosimetry of patients undergoing Total Body and Total Marrow Irradiations (TBI and TMI). Methods: TBI treatments of 12 Gy were delivered in 6 BID fractions with the patient on a moving couch under a static 10 MV beam (Synergy, Elekta). TMI treatments of 18 Gy in 9 BID fractions were planned and delivered using a 6 MV TomoTherapy unit (Accuray). To provide a uniform dose to the entire patient length, the treatment was split into 2 adjacent fields junctioned in the thigh region. Our standard clinical practice involves in vivo dosimetry with MOSFETs for each TBI fraction and TLDs for at least one fraction of the TMI treatment for dose verification. In this study we also used OSLDs. Individual calibration coefficients were obtained for the OSLDs based on irradiations in a solid water phantom to the dose of 50 cGy from Elekta Synergy 10 MV (TBI) and 6 MV (TMI) beams. Calibration coefficients were calculated based on the OSLDs readings taken 2 hrs post-irradiation. For in vivo dosimetry OSLDs were placed alongside MOSFETs for TBI patients and in approximately the same locations as the TLDs for TMI patients. OSLDs were read 2 hours post treatment and compared to the MOSFET and TLD results. Results: OSLD measured doses agreed within 5% with MOSFET and TLD results, with the exception of the junction region in the TMI patient due to very high dose gradient and difficulty of precise and reproducible detector placement. Conclusion: OSLDs are useful for in vivo dosimetry of TBI and TMI patients. The quick post-treatment readout is an advantage over TLDs, allowing the results to be obtained between BID fractions, while wireless detectors are advantageous over MOSFETs for treatments involving a moving couch.

  20. Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy.

    PubMed

    Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

    2015-01-01

    The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (-50 to -6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies. PMID:26151914

  1. Characterization of a commercially-available, optically-stimulated luminescent dosimetry system for use in computed tomography.

    PubMed

    Lavoie, Lindsey; Ghita, Monica; Brateman, Libby; Arreola, Manuel

    2011-09-01

    Optically-stimulated luminescent (OSL) nanoDot dosimeters, commercially available from Landauer, Inc. (Glenwood, IL), were assessed for use in computed tomography (CT) for erasure and reusability, linearity and reproducibility of response, and angular and energy response in different scattering conditions. Following overnight exposure to fluorescent room light, the residual signal on the dosimeters was 2%. The response of the dosimeters to identical exposures was consistent, and reported doses were within 4% of each other. The dosimeters responded linearly with dose up to 1 Gy. The dosimeter response to the CT beams decreased with increased tube voltage, showing up to a -16% difference when compared to a 0.6-cm(3) NIST-traceable calibrated ionization chamber for a 135 kVp CT beam. The largest range in percent difference in dosimeter response to scatter at central and peripheral positions inside CTDI phantoms was 14% at 80 kVp CT tube voltage, when compared to the ionization chamber. The dosimeters responded uniformly to x-ray tube angle over the ranges of increments of 0° to 75° and 105° to 180° when exposed in air, and from 0° to 360° when exposed inside a CTDI phantom. While energy and scatter correction factors should be applied to dosimeter readings for the purpose of determining absolute doses, these corrections are straightforward but depend on the accuracy of the ionization chamber used for cross-calibration. The linearity and angular responses, combined with the ability to reuse the dosimeters, make this OSL system an excellent choice for clinical CT dose measurements. PMID:21799346

  2. Effect of high-dose irradiation on the optically stimulated luminescence of Al2O3:C

    NASA Technical Reports Server (NTRS)

    Yukihara, E. G.; Whitley, V. H.; McKeever, S. W. S.; Akselrod, A. E.; Akselrod, M. S.

    2004-01-01

    This paper examines the effect of high-dose irradiation on the optically stimulated luminescence (OSL) of Al2O3: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+ -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 Al2O3:C. Finally, the implication of these results for the dosimetry of heavy charged particles is discussed. c2004 Elsevier Ltd. All rights reserved.

  3. Evaluation of an X-Ray Dose Profile Derived from an Optically Stimulated Luminescent Dosimeter during Computed Tomographic Fluoroscopy

    PubMed Central

    Hasegawa, Hiroaki; Sato, Masanori; Tanaka, Hiroshi

    2015-01-01

    The purpose of this study was to evaluate scatter radiation dose to the subject surface during X-ray computed tomography (CT) fluoroscopy using the integrated dose ratio (IDR) of an X-ray dose profile derived from an optically stimulated luminescent (OSL) dosimeter. We aimed to obtain quantitative evidence supporting the radiation protection methods used during previous CT fluoroscopy. A multislice CT scanner was used to perform this study. OSL dosimeters were placed on the top and the lateral side of the chest phantom so that the longitudinal direction of dosimeters was parallel to the orthogonal axis-to-slice plane for measurement of dose profiles in CT fluoroscopy. Measurement of fluoroscopic conditions was performed at 120 kVp and 80 kVp. Scatter radiation dose was evaluated by calculating the integrated dose determined by OSL dosimetry. The overall percent difference of the integrated doses between OSL dosimeters and ionization chamber was 5.92%. The ratio of the integrated dose of a 100-mm length area to its tails (−50 to −6 mm, 50 to 6 mm) was the lowest on the lateral side at 80 kVp and the highest on the top at 120 kVp. The IDRs for different measurement positions were larger at 120 kVp than at 80 kVp. Similarly, the IDRs for the tube voltage between the primary X-ray beam and scatter radiation was larger on the lateral side than on the top of the phantom. IDR evaluation suggested that the scatter radiation dose has a high dependence on the position and a low dependence on tube voltage relative to the primary X-ray beam for constant dose rate fluoroscopic conditions. These results provided quantitative evidence supporting the radiation protection methods used during CT fluoroscopy in previous studies. PMID:26151914

  4. Exposure to static magnetic field stimulates quorum sensing circuit in luminescent Vibrio strains of the Harveyi clade.

    PubMed

    Talà, Adelfia; Delle Side, Domenico; Buccolieri, Giovanni; Tredici, Salvatore Maurizio; Velardi, Luciano; Paladini, Fabio; De Stefano, Mario; Nassisi, Vincenzo; Alifano, Pietro

    2014-01-01

    In this study, the evidence of electron-dense magnetic inclusions with polyhedral shape in the cytoplasm of Harveyi clade Vibrio strain PS1, a bioluminescent bacterium living in symbiosis with marine organisms, led us to investigate the behavior of this bacterium under exposure to static magnetic fields ranging between 20 and 2000 Gauss. When compared to sham-exposed, the light emission of magnetic field-exposed bacteria growing on solid medium at 18°C ±0.1°C was increased up to two-fold as a function of dose and growth phase. Stimulation of bioluminescence by magnetic field was more pronounced during the post-exponential growth and stationary phase, and was lost when bacteria were grown in the presence of the iron chelator deferoxamine, which caused disassembly of the magnetic inclusions suggesting their involvement in magnetic response. As in luminescent Vibrio spp. bioluminescence is regulated by quorum sensing, possible effects of magnetic field exposure on quorum sensing were investigated. Measurement of mRNA levels by reverse transcriptase real time-PCR demonstrated that luxR regulatory gene and luxCDABE operon coding for luciferase and fatty acid reductase complex were significantly up-regulated in magnetic field-exposed bacteria. In contrast, genes coding for a type III secretion system, whose expression was negatively affected by LuxR, were down-regulated. Up-regulation of luxR paralleled with down-regulation of small RNAs that mediate destabilization of luxR mRNA in quorum sensing signaling pathways. The results of experiments with the well-studied Vibrio campbellii strain BB120 (originally classified as Vibrio harveyi) and derivative mutants unable to synthesize autoinducers suggest that the effects of magnetic fields on quorum sensing may be mediated by AI-2, the interspecies quorum sensing signal molecule. PMID:24960170

  5. Exposure to Static Magnetic Field Stimulates Quorum Sensing Circuit in Luminescent Vibrio Strains of the Harveyi Clade

    PubMed Central

    Talà, Adelfia; Delle Side, Domenico; Buccolieri, Giovanni; Tredici, Salvatore Maurizio; Velardi, Luciano; Paladini, Fabio; De Stefano, Mario; Nassisi, Vincenzo; Alifano, Pietro

    2014-01-01

    In this study, the evidence of electron-dense magnetic inclusions with polyhedral shape in the cytoplasm of Harveyi clade Vibrio strain PS1, a bioluminescent bacterium living in symbiosis with marine organisms, led us to investigate the behavior of this bacterium under exposure to static magnetic fields ranging between 20 and 2000 Gauss. When compared to sham-exposed, the light emission of magnetic field-exposed bacteria growing on solid medium at 18°C ±0.1°C was increased up to two-fold as a function of dose and growth phase. Stimulation of bioluminescence by magnetic field was more pronounced during the post-exponential growth and stationary phase, and was lost when bacteria were grown in the presence of the iron chelator deferoxamine, which caused disassembly of the magnetic inclusions suggesting their involvement in magnetic response. As in luminescent Vibrio spp. bioluminescence is regulated by quorum sensing, possible effects of magnetic field exposure on quorum sensing were investigated. Measurement of mRNA levels by reverse transcriptase real time-PCR demonstrated that luxR regulatory gene and luxCDABE operon coding for luciferase and fatty acid reductase complex were significantly up-regulated in magnetic field-exposed bacteria. In contrast, genes coding for a type III secretion system, whose expression was negatively affected by LuxR, were down-regulated. Up-regulation of luxR paralleled with down-regulation of small RNAs that mediate destabilization of luxR mRNA in quorum sensing signaling pathways. The results of experiments with the well-studied Vibrio campbellii strain BB120 (originally classified as Vibrio harveyi) and derivative mutants unable to synthesize autoinducers suggest that the effects of magnetic fields on quorum sensing may be mediated by AI-2, the interspecies quorum sensing signal molecule. PMID:24960170

  6. Supramolecular assembly of borate with quaternary ammonium: Crystal structure and tunable luminescent properties

    SciTech Connect

    Liang, Jie; Wang, Yong-gang; Wang, Ying-xia; Liao, Fu-hui; Lin, Jian-hua

    2013-04-15

    A new borate [C{sub 6}H{sub 16}N][B{sub 5}O{sub 6}(OH){sub 4}] (1) is synthesized hydrothermally by the reaction of isopropyltrimethylammonium hydroxide with boric acid. It crystallizes in the triclinic space group P-1 with the parameters a=9.1578(10) Å, b=9.372(9) Å, c=9.9812(10) Å, α=66.508(2)°, β=74.751(2)°, γ=81.893(2)°. The [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions are interlinked via hydrogen bonding forming a 3D supramolecular network containing large cavities, where reside the (CH{sub 3}){sub 3}(i-C{sub 3}H{sub 7}) N{sup +} cations. This borate shows tunable luminescent properties with temperature, heating-treatment, exciting-light, and solvents. The fluorescent intensity of 1 enhances 6-fold with decreasing the temperature from 25 K to 78 K. By treatment under different temperatures, the luminescence of 1 shifted from blue to white and the sample treated at 230 °C emits bright white light to naked eyes. The hybrid borate can disperse in different solvents, and shows a red-shifted and intense emission in polar solvents. - Graphical abstract: The new quaternary ammonium borate [C{sub 6}H{sub 17}N][B{sub 5}O{sub 6}(OH){sub 4}] contains a 3D supramolecular network formed by hydrogen bond linked [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions and shows tunable luminescent properties with temperature, excitation light, and solvents. Highlights: ► A novel quaternary ammonium borate was synthesized. ► It possesses a supramolecular network fomed by H-bonded [B{sub 5}O{sub 6}(OH){sub 4}]{sup −} anions. ► This borate shows tunable luminescent properties with temperature, heating treatment, excitation light, and solvents.

  7. Determination of trapping parameters from thermally stimulated luminescence glow curves of Mn-doped Li2B4O7 phosphor

    NASA Astrophysics Data System (ADS)

    Manam, J.; Sharma, S. K.

    The determination of trapping parameters such as order of kinetics, activation energy and frequency factor is one of the most important studies in the field of thermally stimulated luminescence (TSL). A polycrystalline sample of Mn-doped Li2B4O7 was prepared by melting method. The formation of the doped compound was checked by Fourier transform infrared study. The TSL study of the Mn-doped lithium tetraborate sample shows two glow peaks at 190 °C and 310 °C, of which the intensity of the 310 °C glow peak is the maximum. In this paper, the trapping parameters associated with the prominent glow peak of Mn-doped lithium tetraborate were reported using the isothermal luminescence decay and glow curve shape (Chen's) methods. Our results show a very good agreement between the trapping parameters calculated by the two methods.

  8. Luminescent Eu2O3 nanocrystals by Aspalathus linearis' extract: structural and optical properties

    NASA Astrophysics Data System (ADS)

    Diallo, Abdoulaye; Mothudi, Bakang M.; Manikandan, Elayaperumal; Maaza, Malik

    2016-04-01

    This contribution reports on the synthesis and the main physical properties of europium oxide nanocrystals synthesized for the first time by a completely green physical-chemistry process using Aspalathus linearis' leaves natural extract as an effective chelating agent. The structural and optical properties of such biosynthesized nanocrystals were investigated by electron microscopy, selective electron diffraction, energy dispersive spectroscopy, x-rays diffraction, Raman and x-rays photoelectron spectroscopies, as well as room-temperature photoluminescence. The luminescence properties of such cubic nanocrystals with a 16.5 nm average size were characterized by an intense red emission centered at 614.8 nm (D05-F37) with an average time decay of 7.808 μs.

  9. Optical filtering and luminescence property of some molybdates prepared by combustion synthesis

    SciTech Connect

    Yadav, P. J.; Joshi, C. P.; Moharil, S. V.

    2014-10-15

    As an important class of lanthanide inorganic compounds, rare earth ions doped molybdates have gained much attention due to their attractive luminescence and structural properties, supporting various promising applications as phosphor materials in the fields such as white light-emitting diodes, optical fibers, biolabel, lasers, and so on. The molybdate family has promising trivalent cation conducting properties and most of the optical properties result from electron transitions of the 4f shell, which are greatly affected by the composition and structures of rare-earth compounds. In this paper we report the molybdate CaMoO{sub 4}:Eu{sup 3+} for red SSL and Bi{sub 1.4}Y{sub 0.6}MoO{sub 6}, Y{sub 6}MoO{sub 12} for optical filtering, prepared by one step combustion synthesis.

  10. WE-D-17A-06: Optically Stimulated Luminescence Detectors as ‘LET-Meters’ in Proton Beams

    SciTech Connect

    Granville, D; Sahoo, N; Sawakuchi, GO

    2014-06-15

    Purpose: To demonstrate and evaluate the potential of optically stimulated luminescence (OSL) detectors (OSLDs) for measurements of linear energy transfer (LET) in therapeutic proton beams. Methods: Batches of Al2O2:C OSLDs were irradiated with an absorbed dose of 0.2 Gy in un-modulated proton beams of varying LET (0.67 keV/μm to 2.58 keV/μm). The OSLDs were read using continuous wave (CW-OSL) and pulsed (P-OSL) stimulation modes. We parameterized and calibrated three characteristics of the OSL signals as functions of LET: CW-OSL curve shape, P-OSL curve shape and the ratio of the two OSL emission band intensities (ultraviolet/blue ratio). Calibration curves were created for each of these characteristics to describe their behaviors as functions of LET. The true LET values were determined using a validated Monte Carlo model of the proton therapy nozzle used to irradiate the OSLDs. We then irradiated batches of OSLDs with an absorbed dose of 0.2 Gy at various depths in two modulated proton beams (140 MeV, 4 cm wide spread-out Bragg peak (SOBP) and 250 MeV, 10 cm wide SOBP). The LET values were calculated using the OSL response and the calibration curves. Finally, measured LET values were compared to the true values determined using Monte Carlo simulations. Results: The CW-OSL curve shape, P-OSL curve shape and the ultraviolet/blue-ratio provided proton LET estimates within 12.4%, 5.7% and 30.9% of the true values, respectively. Conclusion: We have demonstrated that LET can be measured within 5.7% using Al2O3:C OSLDs in the therapeutic proton beams used in this investigation. From a single OSLD readout, it is possible to measure both the absorbed dose and LET. This has potential future applications in proton therapy quality assurance, particularly for treatment plans based on optimization of LET distributions. This research was partially supported by the Natural Sciences and Engineering Research Council of Canada.

  11. Re-evaluating the tephrochronology of the Palouse Loess, Washington State, using optically stimulated luminescence dating and single-shard major- and trace-element analyses

    NASA Astrophysics Data System (ADS)

    King, G. E.; Roberts, H. M.; Pearce, N. J.; Gaylord, D.; Sweeney, M.; Duller, G. A.; Smith, V.

    2013-12-01

    Tephra derived from Mount St Helens (MSH) are a critical component of the tephrochronology of the Palouse Loess region, Washington State, USA. New analyses of both source-proximal and -distal tephra units from Washington State using paired major-element and LA-ICP-MS trace-element geochemistry have been undertaken. These analyses reveal that MSH tephra commonly employed to constrain the timing of loess deposition, including tephra from MSH eruptive sets S (~16 ka) and M (~22 ka), cannot be differentiated using major-element chemistry alone. Further, some distal tephra in the Palouse Loess which were previously assigned as MSH Set S on the basis of major-element geochemistry or stratigraphy are now suggested through trace-element analysis to be other tephra, including MSH Set M. Additional support for this re-evaluation of these Palouse Loess tephra units has been provided by luminescence dating of loess that brackets the tephra units. Single-aliquot optically stimulated luminescence (OSL) methods developed for quartz (e.g. Wintle and Murray, 2006), and a new method proposed for dating feldspars (Thomsen et al., 2008; using the ';post-IR IRSL' signal) have been applied at several sites. The ages generated are stratigraphically consistent within each site, and show agreement between the two luminescence methods. Whilst these newly generated luminescence ages are not consistent in all cases with previously published tephra assignments, they are consistent with the revised tephrochronology proposed on the basis of new trace-element geochemistry. This combination of major- plus trace-element geochemistry and luminescence chronology provides a coherent picture of the tephrochronology of the sites examined in the Palouse. More broadly, this highlights the importance of combining both detailed geochemistry and geochronology in areas where tephra are geochemically indistinct. References Wintle A.G. and Murray, A.S., 2006. A review of quartz optically stimulated luminescence

  12. Effect of the glass melting condition on the processing of phosphate-based glass-ceramics with persistent luminescence properties

    NASA Astrophysics Data System (ADS)

    Massera, J.; Gaussiran, M.; Głuchowski, P.; Lastusaari, M.; Petit, L.; Hölsä, J.; Hupa, L.

    2016-02-01

    In this paper, we discuss the impact of the temperature and the duration of the melting on the persistent luminescence properties of phosphate glasses within the P2O5-Na2O-CaO and P2O5-Na2O-SrO systems prepared using a standard melting process in normal atmosphere by adding Sr4Al14O25:Eu2+,Dy3+ microparticles in the glass batch before melting. Glasses with persistent luminescence properties can be successfully prepared if the melting conditions are carefully controlled.

  13. Photon energy dependence of three fortuitous dosemeters from personal electronic devices, measured by optically stimulated luminescence.

    PubMed

    Beerten, Koen; Vanhavere, Filip

    2010-08-01

    New data are presented with regard to the relative OSL sensitivity of three different emergency dosemeters irradiated to various photon energies approximately between 48 and 1250 keV using blue excitation light. Investigated components extracted from commonly worn objects include those from USB flash drives (alumina substrate), mobile phones (Ba-rich silicate) and credit cards (chip card module). Several basic properties have been investigated such as the overall radiation sensitivity, the shape of the decay curve and fading of the OSL signal. An increase of the sensitivity for low energies relative to (60)Co gamma rays can be observed for the three dosemeters, the increase being very pronounced for the Ba-rich component (factor of 10) and less pronounced for the chip card module (factor of 2). It is concluded that proper dose correction factors for photon energy have to be applied in order to accurately determine the absorbed dose to tissue. The OSL sensitivity to neutron irradiation was investigated as well, but this was found to be less than the gamma sensitivity. PMID:20304766

  14. Study of thermoluminescence (TL) and optically stimulated luminescence (OSL) from α-keratin protein found in human hairs and nails: potential use in radiation dosimetry.

    PubMed

    Mishra, D R; Soni, A; Rawat, N S; Bokam, G

    2016-05-01

    The thermoluminescence (TL) and optically stimulated luminescence (OSL) properties of human nails and hairs containing α-keratin proteins have been investigated. For the present studies, black hairs and finger nails were selectively collected from individuals with ages between 25 and 35 years. The collected hairs/nails were cut to a size of < 1 mm and cleaned with distilled water to remove dirt and other potential physical sources of contamination. All samples were optically beached with 470 nm of LED light at 60 mW/cm(2) intensity and irradiated by a (60)Co γ source. The hair and nail samples showed overlapping multiple TL glow peaks in the temperature range from 70 to 210 ° C. Continuous wave (CW)-OSL measurements of hair samples at a wavelength of 470 nm showed the presence of two distinct OSL components with photoionization cross section (PIC) values of about 1.65 × 10(-18) cm(2) and about 3.48 × 10(-19) cm(2), while measurements of nail samples showed PIC values of about 6.98 × 10(-18) cm(2) and about 8.7 × 10(-19) cm(2), respectively. This difference in PIC values for hair and nail samples from the same individual is attributed to different arrangement of α-keratin protein concentrations in the samples. The OSL sensitivity was found to vary ± 5 times among nail and hair samples from different individuals, with significant fading (60% in 11 h) at room temperature. The remaining signal (after fading) can be useful for dose estimation when a highly sensitive OSL reader is used. In the absorbed dose range of 100 mGy-100 Gy, both the TL and OSL signals of hair and nail samples showed linear dose dependence. The results obtained in the present study suggest that OSL using hair and nail samples may provide a supplementary method of dose estimation in radiological and nuclear emergencies. PMID:26846648

  15. Time-resolved optically stimulated luminescence and spectral emission features of α-Al2O3:C

    NASA Astrophysics Data System (ADS)

    Chithambo, M. L.; Nyirenda, A. N.; Finch, A. A.; Rawat, N. S.

    2015-09-01

    This report is concerned with the influence of measurement temperature on luminescence lifetime and on the spectral emission features of luminescence from α-Al2O3:C. The lifetimes were determined from time-resolved luminescence spectra. Spectral measurements were done using thermoluminescence and X-ray excited optical luminescence. The emission spectra of α-Al2O3:C studied in this work shows prominent bands at 330, 380 and 420 nm associated with vacancies in the oxygen sub-lattice in α-Al2O3:C and an additional band at 695 nm due to Cr substitution for Al. Emission bands below 500 nm are independent of temperature below 125 °C but widen with temperature. Direct evidence of thermal quenching of the 420 nm emission band is provided. Beyond 200 °C, the 380 and 420 nm bands merge and widen, with the 420 nm emission dominant. Before the onset of thermal quenching, luminescence lifetimes are affected by retrapping both in the shallow- and in the main electron trap. This was deduced from features of time-resolved luminescence spectra measured from samples with and without the shallow trap. Additional measurements with temperature decreasing from 160 to 20 °C, after phototransfer as well as after a considerable delay between irradiation and measurement, suggest that the change in lifetimes could also be related to other factors including slight shifts in emission wavelength for the 380 and 420 nm emissions.

  16. Luminescence properties of potassium aluminoborate glasses with copper(I) ions at cryogenic temperatures

    NASA Astrophysics Data System (ADS)

    Babkina, A. N.; Sidorov, A. I.; Shirshnev, P. S.

    2014-04-01

    Luminescence spectra of potassium aluminoborate glasses with copper(I) ions have been recorded in the temperature range from +20 to -196°C. It is shown that a decrease in the glass temperature gives rise to thermochromic luminescence, which manifests itself as a red shift of the luminescence band, a value of which reaches 95 nm. This spectral shift is accompanied by a decrease in the luminescence-band amplitude by 30%.

  17. Crystal structures and optical properties of new quaternary strontium europium aluminate luminescent nanoribbons

    DOE PAGESBeta

    Li, Xufan; Budai, John D.; Liu, Feng; Chen, Yu-Sheng; Howe, Jane Y.; Sun, Chengjun; Tischler, Jonathan Zachary; Meltzer, Richard; Pan, Zhengwei

    2014-11-12

    We report the synthesis and characterizations of three series of quaternary strontium europium aluminate (Sr-Eu-Al-O; SEAO) luminescent nanoribbons that show blue, green, and yellow luminescence from localized Eu2+ luminescent centers. These three series of SEAO nanoribbons are: blue luminescent, tetragonal Sr1-xEuxAl6O10 (01-xEuxAl2O4 (01-xEuxAl2O4 (0

  18. Effect of Trace Fe3+ on Luminescent Properties of CaWO4: Pr3+ Phosphors

    NASA Astrophysics Data System (ADS)

    Wang, Ke; Feng, Xu; Feng, Wenlin; Shi, Shasha; Li, Yao; Zhang, Chao

    2016-01-01

    Fe3+ undoped and doped CaWO4: Pr3+ phosphors have been successfully synthesised by using the solid-state reaction method. The products were characterised by powder X-ray diffraction (XRD), photoluminescence (PL) and fluorescence lifetime testing techniques, respectively. The mean crystallite size (50.7 nm) of CaWO4: Pr3+ is obtained from powder XRD data. PL spectra of both Fe3+ undoped and doped CaWO4: Pr3+ phosphors exhibit excitation peaks at 214, 449, 474, and 487 nm under monitor wavelength at 651 nm, and emission peaks at 532, 558, 605, 621, 651, 691, 712, and 736 nm under blue light (λem=487 nm) excitation. The effect of trace Fe3+ on luminescence properties of CaWO4: Pr3+ phosphor is studied by controlling the doping concentration of Fe3+. The results show that radioactive energy transfers from luminescence centre Pr3+ to quenching centre Fe3+ occurred in Fe3+ doped CaWO4: Pr3+ phosphors. With the increasing concentration of Fe3+, the energy transfer from Pr3+ to Fe3+ is enhanced, and the emission intensity of CaWO4: Pr3+ will be lower. The decay times (5.22 and 4.99 μs) are obtained for typical samples Ca0.995WO4: Pr3+0.005 and Ca0.99275WO4: Pr3+0.005, Fe3+0.00225, respectively. This work shows that nonferrous phosphors can improve the luminescent intensity of the phosphors.

  19. Radiation damage and luminescence properties of gamma aluminum oxynitride transparent ceramic

    NASA Astrophysics Data System (ADS)

    Du, Xinhua; Yao, Shiyue; Jin, Xihai; Chen, Haohong; Li, Weifeng; Liang, Bo

    2015-09-01

    This paper reports on the radiation damage of gamma aluminum oxynitride (γ-AlON) transparent ceramic, which remarkably degrades UV-vis transparency and hence limits its applications in optoelectronic devices. The radiation-induced optical absorption of the as-sintered γ-AlON consists of at least two subbands: one is in the UV region with a peak at 270 nm and the other optical absorption band centers at 550 nm, covering the whole visible light spectrum, which makes the sample colored. Interestingly, all the radiation-induced color centers can be completely ‘bleached’ by low temperature annealing. In the thermoluminescence curve, we observed a broad luminescence in the range of 25-300 °C with the peak at 120 °C. Furthermore, the x-ray excited luminescence spectra revealed that there exist multiple emission centers in the γ-AlON. Based on this experimental fact, the radiation damage and luminescent mechanisms were studied. These optical properties of the γ-AlON are considered to be related to defect states. In the as-sintered γ-AlON, charge balancing is realized by the co-existence of \\text{V}\\text{Al}\\prime\\prime \\prime and \\text{O}\\text{N}\\bullet , and the predominant defect form is ≤ft[\\text{V}\\text{Al}\\prime\\prime \\prime-\\text{3O}\\text{N}\\bullet\\right] , which is optically inactive and no optical absorption occurs. However, isolated \\text{V}\\text{Al}\\prime\\prime \\prime and \\text{O}\\text{N}\\bullet can be formed by irradiation and it is these that are responsible for the radiation damage of γ-AlON transparent ceramic. In the end, the UV absorption and visible-light absorption in the irradiated sample were ascribed to VAl-related and ON-related intrinsic defects, respectively.

  20. Synthesis, structure, luminescence and photocatalytic properties of an uranyl-2,5-pyridinedicarboxylate coordination polymer

    NASA Astrophysics Data System (ADS)

    Si, Zhen-Xiu; Xu, Wei; Zheng, Yue-Qing

    2016-07-01

    An uranium coordination polymer, namely [(UO2(pydc)(H2O)]·H2O (1) (H2pydc=2,5-pyridinedicarboxylic acid), has been obtained by hydrothermal method and characterized by X-ray single crystal structure determination. Structural analysis reveals that complex 1 exhibits 1D chain coordination polymer, in which UO22+ ions are bridged by 2,5-pyridinedicarboxylate ligands and the chains are connected into a 3D supramolecular network by O-H···O hydrogen bond interactions and π-π stacking interactions. The photocatalytic properties of 1 for degradation of methylene blue (MB), Rhodamine B (RhB) and methyl orange (MO) under Hg-lamp irradiation have been performed, and the amount of the catalyst as well as Hg-lamp irradiation with different power on the photodegradation efficiency of MB have been investigated. Elemental analyses, infrared spectroscopy, TG-DTA analyses and luminescence properties were also discussed.

  1. Synthesis and luminescence properties of water dispersible Eu3+-doped boehmite nanoparticles

    NASA Astrophysics Data System (ADS)

    Caiut, J. M. A.; Ribeiro, S. J. L.; Messaddeq, Y.; Dexpert-Ghys, J.; Verelst, M.; Dexpert, H.

    2007-11-01

    Nanocrystallized boehmite γ-AlOOH·nH2O had been synthesized by spray-drying (SD) of a solution of aluminium tri-sec-butoxide peptized by nitric acid. The sub-micronic spherical particles obtained had an average diameter of 500 nm and were built of 100 nm or less platelet-like sub-particles. The average crystallite size calculated from XRD was 1.6 nm following the \\vec {b} axis (i.e. one unit cell) and 3-4 nm perpendicular to \\vec {b} . As a result of the nanometric sizes of crystallites, there was a large surface free for water adsorption and it was found to be n = 1.18 ± 0.24H2O per AlOOH. The SD spheres spontaneously dispersed in water at room temperature and formed stable—over months—suspensions with nanometre-size particles (25-85 nm). Luminescent europium-doped nanocrystallized boehmites AlOOH:Eu (Al0.98Eu0.02OOH·nH2O) were synthesized the same way by SD and demonstrated the same crystallization properties and morphologies as the undoped powders. It is inferred from the Eu3+ luminescence spectroscopy that partly hydrated europium species are immobilized on the boehmite nanocrystals where they are directly bonded to α(OH) groups of the AlOOH surface. The europium coordination is schematically written [Eu3+(OH)α(H2O)7-α/2 ]. The europium-doped boehmite from SD spontaneously dispersed in water: the luminescence spectroscopy proves that most of the Eu3+ ions were detached from the NPs during water dispersion. The AlOOH:Eu nanoparticles were modified by the amine acid asparagine (ASN). The modification aimed to render the NPs compatible for further bio-functionalization. After surface modification, the NPs easily dispersed in water; the luminescence spectra after dispersion prove that the Eu3+ ions were held at the boehmite surface.

  2. Synthesis, characterization and luminescence properties of Eu3+-doped hydroxyapatite nanocrystal and the thermal treatment effects

    NASA Astrophysics Data System (ADS)

    Silva, Flávia R. O.; de Lima, Nelson B.; Bressiani, Ana Helena A.; Courrol, Lilia C.; Gomes, Laércio

    2015-09-01

    In this work, we present the synthesis, characterization and the luminescence properties of Ca10(PO4)6(OH)2 (hydroxyapatite/HAp) nanocrystals doped with europium trivalent ions. The most important processes that lead to europium emissions in the visible region were identified. Eu:HAp nanopowder excited at 394 nm (or 460 nm) exhibits several emissions: (i) weak emissions at 579 nm, 592 nm and 616 nm due to the 5D0 → 7F0, 5D0 → 7F1 and 5D0 → 7F2 transitions, respectively, with europium ion occupying site I in hydroxyapatite structure and (ii) strong emissions due to the 5D0 → 7F0 (574 nm), 5D0 → 7F1 (602 nm) and 5D0 → 7F2 (610-630 nm) transitions, when Eu3+ is occupying site II. The emission spectrum and the time-resolved luminescence analysis showed that the HAp nanocrystals (nanopowder) thermally treated at temperature (T) between 500 and 800 °C have a change in the initial Eu3+ site distribution of 100 % of Eu3+ at site I to a more stable one where the majority of europium ions are at site II: 30% remains at site I and 70% migrates to site II. In addition, an enhancement of the Eu3+ emission intensity is observed due to the increasing crystallite size. A time-resolved luminescence investigation using a short pulse laser excitation at 460 nm was employed to measure the luminescence decays and to determine the most important mechanisms involved in the deexcitation process of 5D0 excited state of Eu3+, where it is seen a fast (2.9 μs) energy transfer from Eu3+- site I (donor) to Eu3+- site II (acceptor) in the thermally treated nanopowders with T > 500 °C. The initial presence of 100% of Eu3+ at site I in the synthesized nanocrystals is gradually modified by the thermal treatments with temperatures above 500 °C by thermal activation of Ca2+ vacancy (the charge compensator) diffusion through the HAp lattice, which propitiates the Ca2+- vacancies and Eu3+ ions to exchange positions in the lattice. By this thermal activated mechanism, Eu3+ ion migrates

  3. Two novel 2D lanthanide sulfate frameworks: Syntheses, structures, and luminescence properties

    NASA Astrophysics Data System (ADS)

    Li, Zhong-Yi; Zhang, Chi; Zhang, Fu-Li; Zhang, Fu-Qiang; Zhang, Xiang-Fei; Li, Su-Zhi; Cao, Guang-Xiu; Zhai, Bin

    2016-03-01

    Two novel lanthanide-sulfate compounds, [Ln2(SO4)3(H2O)8] (Ln = Tb (1) and Dy (2)), have been synthesized under hydrothermal reactions. X-ray crystal structure analyses reveal that 1 and 2 are isomorphous and crystallize in monoclinic C2/c pace group, showing a layered structure. The layers bear a rare quasi-honeycomb metal arrangement, which is fastened by μ3 = η1:η1:η1 and μ2 = η1:η1 sulfates. If assigning the μ3 = η1:η1:η1 sulfate as a 3-connected node and the Ln3+ ion as a 4-connected node, the network can be rationalized as a binodal (3,4)-connected V2O5 topology with a Schäfli symbol of (42·63·8) (42·6). In addition, the infrared, thermogravimetric analysis and luminescent properties were also studied. Complexes 1 and 2 exhibit outstanding thermal stability and characteristic terbium and dysprosium luminescence.

  4. Supramolecular assembly of borate with quaternary ammonium: Crystal structure and tunable luminescent properties

    NASA Astrophysics Data System (ADS)

    Liang, Jie; Wang, Yong-gang; Wang, Ying-xia; Liao, Fu-hui; Lin, Jian-hua

    2013-04-01

    A new borate [C6H16N][B5O6(OH)4] (1) is synthesized hydrothermally by the reaction of isopropyltrimethylammonium hydroxide with boric acid. It crystallizes in the triclinic space group P-1 with the parameters a=9.1578(10) Å, b=9.372(9) Å, c=9.9812(10) Å, α=66.508(2)°, β=74.751(2)°, γ=81.893(2)°. The [B5O6(OH)4]- anions are interlinked via hydrogen bonding forming a 3D supramolecular network containing large cavities, where reside the (CH3)3(i-C3H7) N+ cations. This borate shows tunable luminescent properties with temperature, heating-treatment, exciting-light, and solvents. The fluorescent intensity of 1 enhances 6-fold with decreasing the temperature from 25 K to 78 K. By treatment under different temperatures, the luminescence of 1 shifted from blue to white and the sample treated at 230 °C emits bright white light to naked eyes. The hybrid borate can disperse in different solvents, and shows a red-shifted and intense emission in polar solvents.

  5. Hydrothermal synthesis and luminescence properties of KLa):Eu3+ phosphor

    NASA Astrophysics Data System (ADS)

    Yang, Zaifa; Sun, Yumei; Han, Liu; Xu, Denghui; Sun, Jiayue

    2016-04-01

    KLa):Eu3+ phosphors were prepared by the hydrothermal method. The after tuning of synthesis time and the ratio of the ethylene glycol to water ratio made the phosphor present different morphologies, including peanut-like shape and spheres. The samples were characterized by x-ray diffraction (XRD), scanning electron microscope (SEM), diffuse reflectance spectrum, and fluorescence spectrum. Under the excitation of 397 nm near-ultraviolet, the typical red emission produced by Eu3+ ions can be observed. And the phosphors show strong red light around 612 nm, attributed to D→F transition of Eu ion. The luminescence properties of the as-prepared phosphors were studied based on changing the synthesis condition. It is found that the synthesis time and the changing of the ratio of ethylene glycol to water play the crucial role in the formation of morphology. The optimum dopant concentration of Eu ions in KLa):Eu3+ is around 7 mol. %. Moreover, the fluorescence decay curve and thermal stability of luminescence were also investigated in detail. The Commission International de I'Eclairage coordinates of KLa):0.07Eu3+ located in the red reddish region. All the results suggest that KLa):0.07Eu3+ might be a promising reddish-orange emitting phosphor used in white light-emitting diodes (w-LED).

  6. Luminescence and scintillation properties of BaF2sbnd Ce transparent ceramic

    NASA Astrophysics Data System (ADS)

    Luo, Junming; Sahi, Sunil; Groza, Michael; Wang, Zhiqiang; Ma, Lun; Chen, Wei; Burger, Arnold; Kenarangui, Rasool; Sham, Tsun-Kong; Selim, Farida A.

    2016-08-01

    Cerium doped Barium Fluoride (BaF2sbnd Ce) transparent ceramic was fabricated and its luminescence and scintillation properties were studied. The photoluminescence shows the emission peaks at 310 nm and 323 nm and is related to the 5d-4f transitions in Ce3+ ion. Photo peak at 511 keV and 1274 keV were obtained with BaF2sbnd Ce transparent ceramic for Na-22 radioisotopes. Energy resolution of 13.5% at 662 keV is calculated for the BaF2sbnd Ce transparent ceramic. Light yield of 5100 photons/MeV was recorded for BaF2sbnd Ce(0.2%) ceramic and is comparable to its single crystal counterpart. Scintillation decay time measurements shows fast component of 58 ns and a relatively slow component of 434 ns under 662 keV gamma excitation. The slower component in BaF2sbnd Ce(0.2%) ceramic is about 200 ns faster than the STE emission in BaF2 host and is associated with the dipole-dipole energy transfer from the host matrix to Ce3+ luminescence center.

  7. Persistently luminescent and photocatalytic properties of ZnGa2O4 phosphors

    NASA Astrophysics Data System (ADS)

    Li, Darong; Wang, Yinhai; Xu, Ke; Li, Lei; Hu, Zhengfa

    2015-04-01

    The phosphors ZnGa2O4 were synthesized via high temperature solid-state reaction. The crystal structure, photoluminescence, persistent luminescence, and photocatalytic properties of ZnGa2O4 were studied in detail. The x-ray diffraction patterns showed that some remaining phases of ZnO and β-Ga2O3 appeared with the excess amount of ZnO and Ga2O3, respectively. The results of the Raman spectra indicated that the first order Raman active modes of ZnGa2O4 were attributed to O2- ions and Zn2+ ions in tetrahedral sites. The phosphors exhibited a broad-band emission around 430 nm, which could be ascribed to the Ga-O transition of regular octahedral sites in the spinel lattice of ZnGa2O4. It also exhibited the emission peak around 430 nm shift to longer wavelength with the amount of the excess ZnO. The persistent luminescence of ZnGa2O4 could be observed for 10 min by naked eyes at room temperature under 254 nm ultraviolet (UV) excitation. In addition, photocatalytic activity test showed that ZnGa2O4 exhibited excellent photocatalytic activity for the degradation of Rhodamine B by the UV irradiation. It was indicated that the traps played an important role in trapping the electrons or holes to decrease the combination of the holes or electrons producing by the irradiation.

  8. Hydrothermal Synthesis and Luminescence Property of Nanoscaled BiPO4:Eu3+ Powders.

    PubMed

    Shi, Xiaolei; Liu, Yun; Zhang, Jin; Zhang, Kun; Li, Peng; Zuo, Haoqiang

    2016-04-01

    A series of Bi1-xPO4:xEu3+ phosphors were prepared using a simple hydrothermal method. The effects of pH and Eu3+ doping on the structure, morphology and luminescence properties of BiPO4:Eu3+ were investigated systematically. X-ray diffraction (XRD) and field emission scanning electron microscope (FE-SEM) results reveal that the as-prepared BiPO4 crystals are in a low temperature monoclinic phase (LTMP), and have a rod-like structure with a size in the range of 1-5 µm at pH 1. Increasing the pH to 2 transforms the BiPO4 to its hexagonal phase (HP), with peanut-like structures ranging from 50 to 150 nm. At pH 1, when the doping level is increased to 0.07, the phase transformation from LTMP to HP occurs, meaning that the amount of HP components increase with increasing Eu3+ doping. Furthermore, all the diffraction peaks of the Bi1-xPO4:xEu3+ can be fitted very well to HP when x = 0.11. The photoluminescence (PL) spectra suggest that orange-red luminescence can be observed in the series of BiPO4:Eu3+ phosphors, and that concentration quenching occurs when x = 0.07. PMID:27451718

  9. Syntheses, crystal structures, magnetic and luminescence properties of five novel lanthanide complexes of nitronyl nitroxide radical

    SciTech Connect

    Wang, Ya-Li; Gao, Yuan-Yuan; Ma, Yue; Wang, Qing-Lun; Li, Li-Cun; Liao, Dai-Zheng

    2013-06-01

    Five novel Ln(III) complexes based on a new nitronyl nitroxide radical have been synthesized, characterized structurally and magnetically: [Ln(hfac)₃(NITPh-3-Br-4-OMe)₂] (Ln(III)=Eu(1), Gd(2), Tb(3), Dy(4), Ho(5); hfac=hexafluoroacetylacetonate; and NITPh-3-Br-4-OMe=2-3´-Br-4´-methoxyphenyl-4,4,5,5 -tetramethylimidazoline-1-oxyl-3-oxide). The single-crystal structures analyses show that these complexes have similar mononuclear tri-spin structures, in which central Ln(III) ions are all eight coordinated by three hfac molecules and two NITPh-3-Br-4-OMe radicals. The variable-temperature magnetic susceptibility studies reveal the antiferromagnetic interactions between the paramagnetic ions (Ln(III) and radicals) in complexes 1, 2, 3 and 5 and ferromagnetic interaction in complex 4. The luminescence characterizations of complexes Eu(1), Tb(3) and Dy(4) are also studied in this paper. - Graphical abstract: Using a novel halogen phenyl-substituted nitronyl-nitroxide radical, we obtained and characterized five isostructural lanthanide mononuclear tri-spin compounds. Highlights: • A new halogen phenyl-substituted nitronyl-nitroxide radical was designed. • Five new Ln(III) radical complexes have been synthesized and characterized. • The reasonable evaluation the magnetic interactions between Ln(III) ions and radical is meaningful. • These complexes show good luminescent properties.

  10. Tuning the cellular uptake properties of luminescent heterobimetallic iridium(III)-ruthenium(II) DNA imaging probes.

    PubMed

    Wragg, Ashley; Gill, Martin R; Turton, David; Adams, Harry; Roseveare, Thomas M; Smythe, Carl; Su, Xiaodi; Thomas, Jim A

    2014-10-20

    The synthesis of two new luminescent dinuclear Ir(III)-Ru(II) complexes containing tetrapyrido[3,2-a:2',3'-c:3'',2''-h:2''',3'''-j]phenazine (tpphz) as the bridging ligand is reported. Unlike many other complexes incorporating cyclometalated Ir(III) moieties, these complexes display good water solubility, allowing the first cell-based study on Ir(III)-Ru(II) bioprobes to be carried out. Photophysical studies indicate that emission from each complex is from a Ru(II) excited state and both complexes display significant in vitro DNA-binding affinities. Cellular studies show that each complex is rapidly internalised by HeLa cells, in which they function as luminescent nuclear DNA-imaging agents for confocal microscopy. Furthermore, the uptake and nuclear targeting properties of the complex incorporating cyclometalating 2-(4-fluorophenyl)pyridine ligands around its Ir(III) centre is enhanced in comparison to the non-fluorinated analogue, indicating that fluorination may provide a route to promote cell uptake of transition-metal bioprobes. PMID:25208528

  11. Microsphere morphology tuning and photo-luminescence properties of monoclinic Y2WO6

    NASA Astrophysics Data System (ADS)

    Gao, Hong; Bai, Yulong; Zhang, Junying; Tang, Zilong

    2015-04-01

    Effects of the solution pH value and reaction time on the precursor morphology and photoluminescence properties are investigated for hydrothermally prepared monoclinic Y2WO6 phosphors. In the near-neutral environment, sodium dodecyl benzene sulfonate (SDBS) surfactant forms small microspheres micelles as template to synthesize microspherical precursor. H+ ions concentration affects the arrangement of negative ionic surfactant SDBS. As a result, jujube-liked and popcorn-like loose microspheres formed at low pH value. When the pH value is 5.2 and the hydrothermal reaction time reaches 24 h, respectively, the strongest luminescent intensity can be obtained. Under this condition, the precursor presented regular microsphere with diameter of 4.0 μm. After high-temperature heat treatment, the obtained phosphor particles still exhibit microsphere-like shape. Therefore, we provide an effective method to tune the morphology of Y2WO6 phosphors and study the relationship between morphology and luminescent performance.

  12. Time-resolved optically stimulated luminescence of Al2O3:C for ion beam therapy dosimetry

    NASA Astrophysics Data System (ADS)

    Yukihara, Eduardo G.; Doull, Brandon A.; Ahmed, Md; Brons, Stephan; Tessonnier, Thomas; Jäkel, Oliver; Greilich, Steffen

    2015-09-01

    The objective of this study was to characterize the time-resolved (TR) optically stimulated luminescence (OSL) from Al2O3:C detectors and investigate methodologies to improve the accuracy of these detectors in ion beam therapy dosimetry, addressing the reduction in relative response to high linear energy transfer (LET) particles common to solid-state detectors. Al2O3:C OSL detectors (OSLDs) were exposed to proton, 4He, 12C and 16O beams in 22 particle/energy combinations and read using a custom-built TR-OSL reader. The OSL response {{r}\\text{OSL}} , relative to 60Co gamma dose to water, and the ratio between the UV and blue OSL emission bands of Al2O3:C (UV/blue ratio) were determined as a function of the LET. Monte-Carlo simulations with the multi-purpose interaction and transport code FLUKA were used to estimate the absorbed doses and particle energy spectra in the different irradiation conditions. The OSL responses {{r}\\text{OSL}} varied from 0.980 (0.73 keV μm-1) to 0.288 (120.8 keV μm-1). The OSL UV/blue ratio varied by a factor of two in the investigated LET range, but the variation for 12C beams was only 11%. OSLDs were also irradiated at different depths of carbon ion spread-out Bragg peaks (SOBPs), where it was shown that doses could be obtained with an accuracy of  ±2.0% at the entrance channel and within the SOBP using correction factors calculated based on the OSL responses obtained in this study. The UV/blue ratio did not allow accurate estimation of the dose-averaged LET for 12C SOBPs, although the values obtained can be explained with the data obtained in this study and the additional information provided by the Monte-Carlo simulations. The results demonstrate that accurate OSLD dosimetry can be performed in ion beam therapy using appropriate corrections for the OSL response.

  13. Photoluminescence, thermally stimulated luminescence and electron paramagnetic resonance investigations of Tb{sup 3+} doped SrBPO{sub 5}

    SciTech Connect

    Kumar, Mithlesh; Seshagiri, T.K.; Kadam, R.M.; Godbole, S.V.

    2011-09-15

    Graphical abstract: EPR spectra of BOHC's in 2 kGy {gamma}-irradiated SrBPO{sub 5}:Tb sample using Receiver Gain RG = 4 x 10{sup 4}, Modulation Amplitude MA = 0.25 G, Microwave power setting 6.3 mW: (A) un-annealed sample recorded at 300 K, (B) un-annealed sample recorded at 100 K and (C) sample annealed at 550 K for 10 min and recorded at 100 K. Highlights: {yields} PL studies on Tb doped SrBPO{sub 5} phosphor have shown emission due to Tb{sup 3+} associated with {sup 5}D{sub 3} {yields} {sup 7}F{sub J} and {sup 5}D{sub 4} {yields} {sup 7}F{sub J} (J = 3, 4, 5 and 6) transitions. {yields} The EPR studies on {gamma}-irradiated samples revealed formation of three types of boron oxygen hole trapped centres viz., BOHC{sub 1}, BOHC{sub 2} and BOHC{sub 3} and an electron trapped centre. {yields} The TSL peak at 475 K was associated with the thermal destruction of BOHC{sub 2}. -- Abstract: Trap level spectroscopic studies were carried out on {gamma}-irradiated Tb (1 mole%) doped SrBPO{sub 5} were carried out using photoluminescence (PL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) techniques. The incorporation of Tb in the 3+ oxidation state was ascertained from PL studies. Life time for Tb{sup 3+} emission corresponding to the intense transition {sup 5}D{sub 4} {yields} {sup 7}F{sub 5} at 543 nm was determined. The spectral characteristics of the TSL glows have shown that Tb{sup 3+} ions act as the emission center for the glow peak at 475 K. The trap parameters of the glow peak were determined. EPR investigations at room temperature/77 K revealed the stabilization of three boron oxygen hole trapped centers (BOHC's) and oxygen centered radicals such as O{sup -} and O{sub 2}{sup -} and trapped electrons in room temperature {gamma}-irradiated samples. TSL glow peak at 475 K was found to be associated with recombination of electron released from trapped electron center and the BOHC{sub 2} center.

  14. Angular dependence of dose sensitivity of nanoDot optically stimulated luminescent dosimeters in different radiation geometries

    SciTech Connect

    Jursinic, Paul A.

    2015-10-15

    Purpose: A type of in vivo dosimeter, an optically stimulated luminescent dosimeter, OSLD, may have dose sensitivity that depends on the angle of incidence of radiation. This work measures how angular dependence of a nanoDot changes with the geometry of the phantom in which irradiation occurs and with the intrinsic structure of the nanoDot. Methods: The OSLDs used in this work were nanoDot dosimeters (Landauer, Inc., Glenwood, IL), which were read with a MicroStar reader (Landauer, Inc., Glenwood, IL). Dose to the OSLDs was delivered by 6 MV x-rays. NanoDots with various intrinsic sensitivities were irradiated in numerous phantoms that had geometric shapes of cylinders, rectangles, and a cube. Results: No angular dependence was seen in cylindrical phantoms, cubic phantoms, or rectangular phantoms with a thickness to width ratio of 0.3 or 1.5. An angular dependence of 1% was observed in rectangular phantoms with a thickness to width of 0.433–0.633. A group of nanoDots had sensitive layers with mass density of 2.42–2.58 g/cm{sup 3} and relative sensitivity of 0.92–1.09 and no difference in their angular dependence. Within experimental uncertainty, nanoDot measurements agree with a parallel-plate ion chamber at a depth of maximum dose. Conclusions: When irradiated in cylindrical, rectangular, and cubic phantoms, nanoDots show a maximum angular dependence of 1% or less at an incidence angle of 90°. For a sample of 78 new nanoDots, the range of their relative intrinsic sensitivity is 0.92–1.09. For a sample of ten nanoDots, on average, the mass in the sensitive layer is 73.1% Al{sub 2}O{sub 3}:C and 26.9% polyester. The mass density of the sensitive layer of a nanoDot disc is between 2.42 and 2.58 g/cm{sup 3}. The angular dependence is not related to Al{sub 2}O{sub 3}:C loading of the nanoDot disc. The nanoDot at the depth of maximum dose has no more angular dependence than a parallel-plate ion chamber.

  15. An assessment of the utility of optically-stimulated luminescence to date sediments from Lakes Malawi, Bosumtwi, and Tanganyika, Africa

    NASA Astrophysics Data System (ADS)

    Gomez, J.; Forman, S. L.; Pierson, J.; Scholz, C.; Peck, J.; Heil, C.; King, J.; Shanahan, T.; Overpeck, J.; Koeberl, C.; Milkereit, B.

    2005-12-01

    An exciting recent development in geochronology is the advent of optically-stimulated luminescence (OSL) for dating late Quaternary sediments. OSL signal of mineral grains is reset by exposure to sunlight prior to deposition and a time-sensitive charge is acquired from exposure to ionizing radiation post burial. The OSL signal is highly sensitive to solar resetting, with background counts rendered after few minutes of sunlight exposure. OSL geochronology can yield decadal resolution in the past 1000 years, a period of limited precision for radiocarbon dating and potentially date sediment spanning the past 200 to 400 ka. Nearly continuous sedimentary records from African lakes provide unparalleled opportunities to develop new OSL dating approaches to constrain hydro-climatic events in the tropics. A variety of OSL geochronologic approaches are attempted for sediments from Lakes Malawi, Bosumtwi and Tanganyika providing an internal test of reproducibility. Accuracy is assessed by OSL dating levels with radiocarbon ages and with correlated chronologic control e.g. from the sediment magnetic signature or sediment carbon to atmosphere methane relations. The fine-grained (3-11 micron) polymineral and quartz fractions and for coarser levels the quartz fine sand is extracted for dating. Additive and regenerative dose procedures using multiple and single aliquots under blue, green and infrared light exposure are used to estimate the post-burial paleodose. A regenerative procedure with dose normalization and stepped preheating (140-180° C) provides a particularly robust approach for dating sediments greater than 75 ka. OSL emissions for sediment from Lake Malawi for the past ca. 100 ka are not at saturated dose and are amenable for dating by a variety of methods. In contrast sediments from Lake Bosumtwi, with a probable Sahel dust source, exhibit saturation in OSL signal for sediments ca. 100 ka old, necessitating the using of regenerative approaches. The concordance

  16. Time-resolved optically stimulated luminescence of Al2O3:C for ion beam therapy dosimetry.

    PubMed

    Yukihara, Eduardo G; Doull, Brandon A; Ahmed, Md; Brons, Stephan; Tessonnier, Thomas; Jäkel, Oliver; Greilich, Steffen

    2015-09-01

    The objective of this study was to characterize the time-resolved (TR) optically stimulated luminescence (OSL) from Al2O3:C detectors and investigate methodologies to improve the accuracy of these detectors in ion beam therapy dosimetry, addressing the reduction in relative response to high linear energy transfer (LET) particles common to solid-state detectors. Al2O3:C OSL detectors (OSLDs) were exposed to proton, (4)He, (12)C and (16)O beams in 22 particle/energy combinations and read using a custom-built TR-OSL reader. The OSL response rOSL, relative to (60)Co gamma dose to water, and the ratio between the UV and blue OSL emission bands of Al2O3:C (UV/blue ratio) were determined as a function of the LET. Monte-Carlo simulations with the multi-purpose interaction and transport code FLUKA were used to estimate the absorbed doses and particle energy spectra in the different irradiation conditions. The OSL responses rOSL varied from 0.980 (0.73 keV μm(-1)) to 0.288 (120.8 keV μm(-1)). The OSL UV/blue ratio varied by a factor of two in the investigated LET range, but the variation for (12)C beams was only 11%. OSLDs were also irradiated at different depths of carbon ion spread-out Bragg peaks (SOBPs), where it was shown that doses could be obtained with an accuracy of ± 2.0% at the entrance channel and within the SOBP using correction factors calculated based on the OSL responses obtained in this study. The UV/blue ratio did not allow accurate estimation of the dose-averaged LET for (12)C SOBPs, although the values obtained can be explained with the data obtained in this study and the additional information provided by the Monte-Carlo simulations. The results demonstrate that accurate OSLD dosimetry can be performed in ion beam therapy using appropriate corrections for the OSL response. PMID:26270884

  17. Quasi-spherical LuBO{sub 3} nanoparticles: Synthesis, formation, and luminescence properties

    SciTech Connect

    Gao, Yu; Yang, Feng; Han, Wenchi; Fang, Qinghong; Xu, Zhenhe

    2014-03-01

    Graphical abstract: Quasi-spherical LuBO3 nanoparticles have been prepared via a facile hydrothermal route. The possible growth mechanism and the luminescent properties of the as-prepared microcrystals have been discussed. - Highlights: • LuBO{sub 3} nanoparticles were prepared by a facile hydrothermal route. • The Eu{sup 3+} and Tb{sup 3+}-doped LuBO{sub 3} products show strong red and green emissions. • This method may be more widely applicable in the design of other rare-earth compounds. - Abstract: Quasi-spherical LuBO{sub 3} nanoparticles have been successfully synthesized by a designed hydrothermal conversion method. The Lu(OH)CO{sub 3} nanoparticles were first prepared by a simple homogeneous precipitation method. Subsequently, LuBO{sub 3} nanoparticles were synthesized at the expense of the Lu(OH)CO{sub 3} nanoparticles during a hydrothermal conversion process. The conversion process from the Lu(OH)CO{sub 3} precursor to LuBO{sub 3} nanoparticles was investigated by time-dependent experiments. Moreover, the as-obtained Eu{sup 3+} and Tb{sup 3+}-doped LuBO{sub 3} products show strong characteristic red and green emissions under ultraviolet excitation and low-voltage electron beam excitation, respectively. This work sheds some light on the knowledge of conversion of different kind of lutetium compounds, and the luminescent properties have potential applications in fluorescent lamps and field emission displays. More importantly, this simple method is expected to allow the large-scale production of other complex rare-earth compounds with controllable morphologies and sizes, and exploration of the morphology and photoluminescence properties.

  18. Density functional theory predictions for blue luminescence and nonlinear optical properties of carbon-doped gallium nitride

    NASA Astrophysics Data System (ADS)

    Hu, XiaoLin; Zhang, YongFan; Zhuang, NaiFeng; Li, JunQian

    2010-12-01

    The TD-B3LYP method and the plane-wave formalism of DFT method were applied to predict the blue luminescence and nonlinear optical effect of C-doped GaN, respectively. The introduction of carbon dopant will generate different acceptor or donor levels, which are mainly composed by p electronic state, within the energy gap of GaN. Exploring the calculated luminescence spectra based on the optimized excited-state structure, C N:GaN exhibits high luminescence intensity and has nice monochromatic property. In addition, the corresponding second-order nonlinear optical coefficients are considerable, χ(2)xzx=-15.07 pm/V and χ(2)zzz=26.91 pm/V, which are about 28 times and 50 times of the second-order optical coefficient of KDP crystal.

  19. Luminescence properties of compounds of europium(III) with quinaldic acid and phosphor-containing neutral ligands

    NASA Astrophysics Data System (ADS)

    Kalinovskaya, I. V.

    2016-06-01

    Luminescent complex mixed-ligand compounds of europium(III) with quinaldic acid and phosphor- containing neutral ligands have been obtained. Their composition and structure have been determined. The thermal and spectral-luminescent properties of the obtained complex mixed-ligand compounds of europium( III) have been studied. It is shown that, during thermolysis, a water molecule and neutral ligand are detached in two stages with endothermic effects. It is established that quinaldinate ion is coordinated to europium(III) ion in a bidentate fashion. The Stark structure of the 5 D 0-7 F j ( j = 0, 1, 2) transitions in low-temperature luminescence spectra of complex compounds of europium(III) has been analyzed.

  20. Aqueous based synthesis of CdSe/ZnS Q-dots: Study on luminescence properties and cytotoxicity

    NASA Astrophysics Data System (ADS)

    Painuly, Diksha; Bhatt, Anugya; Krishnan, V. Kalliyana

    2013-06-01

    Present study aims to modify the thioacid capped CdSe Quantum-dots (Q-dots) surface by ZnS coating by direct synthesis in aqueous medium. CS formation was confirmed by red shift as well as enhancement in the luminescence peak compared to bare Q-dots. Effects of processing parameters during the shell preparation such as core concentration and sulphur concentration on the luminescence properties of CS have been studied. Processing parameters have been optimized at maximum luminescence efficiency. Cytocompatibility behavior was found to be better for CS compared to their bare Q-dots counterpart after evaluation. Cytotoxicity of CS has been further evaluated by changing the sulphur concentration and after aging for 8 days.

  1. Effects of Co content on the structural, luminescence, and ferromagnetic properties of Zn1-xCoxSy films

    NASA Astrophysics Data System (ADS)

    Ni, Wei-Shih; Lin, Yow-Jon

    2012-09-01

    This study investigates the effect of Co content on the structural, luminescence, and ferromagnetic properties of sol-gel Zn1-xCoxSy films by x-ray diffraction, photoluminescence, energy dispersive spectrometer, atomic force microscopy, and alternating gradient magnetometer measurements. It is shown that Co doping may lead to weakened intensity of the defect-related luminescence and the intensity of the defect-related luminescence decreases with increasing Co content. Changes in Co concentration are important issues for improving crystal quality of ZnS films. It is also found that the defects play important roles in determining the ferromagnetic characteristics of the Zn1-xCoxSy films.

  2. Synthesis, characterisation, optical and luminescence properties of CoAl{sub 2}O{sub 4}

    SciTech Connect

    Agilandeswari, K.; Kumar, A. Ruban

    2015-06-24

    Solid state method has been used as an efficient method to synthesize blue pigment CoAl{sub 2}O{sub 4} at a temperature of 800°C. The products were characterized by powder X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FTIR), UV-Visible diffuse reflectance spectroscopy (DRS) and luminescent spectroscopy. X-ray diffraction pattern confirmed the formation of single phase CoAl{sub 2}O{sub 4}. Optical properties of CoAl{sub 2}O{sub 4} ceramic shows an energy band gap in the range of 3.10eV. The emission spectra of spinel CoAl{sub 2}O{sub 4} in the visible region confirmed the presence of tetrahedral coordinated Co{sup 2+} ions.

  3. Polyaniline-coated upconversion nanoparticles with upconverting luminescent and photothermal conversion properties for photothermal cancer therapy

    PubMed Central

    Xing, Yadong; Li, Luoyuan; Ai, Xicheng; Fu, Limin

    2016-01-01

    In this study, we developed a nanosystem based on upconversion nanoparticles (UCNPs) coated with a layer of polyaniline nanoparticles (PANPs). The UCNP induces upconversion luminescence for imaging and photothermal conversion properties are due to PANPs. In vitro experiments showed that the UCNPs-PANPs were nontoxic to cells even at a high concentration (800 µg mL−1). Blood analysis and histological experiments demonstrated that the UCNPs-PANPs exhibited no apparent toxicity in mice in vivo. Besides their efficacy in photothermal cancer cell ablation, the UCNP-PANP nanosystem was found to achieve an effective in vivo tumor ablation effect after irradiation using an 808 nm laser. These results demonstrate the potential of the hybrid nanocomposites for use in imaging-guided photothermal therapy. PMID:27621625

  4. Synthesis of Firefly Luciferin Analogues and Evaluation of the Luminescent Properties.

    PubMed

    Ioka, Shuji; Saitoh, Tsuyoshi; Iwano, Satoshi; Suzuki, Koji; Maki, Shojiro A; Miyawaki, Atsushi; Imoto, Masaya; Nishiyama, Shigeru

    2016-06-27

    Five new firefly luciferin (1) analogues were synthesized and their light emission properties were examined. Modifications of the thiazoline moiety in 1 were employed to produce analogues containing acyclic amino acid side chains (2-4) and heterocyclic rings derived from amino acids (5 and 6) linked to the benzothiazole moiety. Although methyl esters of all of the synthetic derivatives exhibited chemiluminescence activity, only carboluciferin (6), possessing a pyrroline-substituted benzothiazole structure, had bioluminescence (BL) activity (λmax =547 nm). Results of bioluminescence studies with AMP-carboluciferin (AMP=adenosine monophosphate) and AMP-firefly luciferin showed that the nature of the thiazoline mimicking moiety affected the adenylation step of the luciferin-luciferase reaction required for production of potent BL. In addition, BL of 6 in living mice differed from that of 1 in that its luminescence decay rate was slower. PMID:27220106

  5. Influence of substrate miscut angle on surface morphology and luminescence properties of AlGaN

    SciTech Connect

    Kusch, Gunnar Edwards, Paul R.; Bruckbauer, Jochen; Martin, Robert W.; Li, Haoning; Parbrook, Peter J.; Sadler, Thomas C.

    2014-03-03

    The influence of substrate miscut on Al{sub 0.5}Ga{sub 0.5} N layers was investigated using cathodoluminescence (CL) hyperspectral imaging and secondary electron imaging in an environmental scanning electron microscope. The samples were also characterized using atomic force microscopy and high resolution X-ray diffraction. It was found that small changes in substrate miscut have a strong influence on the morphology and luminescence properties of the AlGaN layers. Two different types are resolved. For low miscut angle, a crack-free morphology consisting of randomly sized domains is observed, between which there are notable shifts in the AlGaN near band edge emission energy. For high miscut angle, a morphology with step bunches and compositional inhomogeneities along the step bunches, evidenced by an additional CL peak along the step bunches, are observed.

  6. The morphology, microstructure, and luminescent properties of CdS/CdTe films

    SciTech Connect

    Al-Jassim, M.M.; Dhere, R.G.; Jones, K.M.; Hasoon, F.S.; Sheldon, P.

    1998-09-01

    This paper is concerned with the characterization of CdS/CdTe polycrystalline thin films for solar cells. The morphology, microstructure, and luminescent properties are studied by a powerful array of characterization techniques. The presence of pinholes in 100-nm thick CdS is observed. The microstructure of CdS and CdTe films is shown to be heavily faulted polycrystalline. The effect of deposition temperature on the grain size and the microstructure is investigated. The interdiffusion of sulfur and tellurium at the CdS/CdTe interface is studied for the first time by a nanoprobe technique. Considerable amount of sulfur is detected in CdTe in the vicinity of the interface of samples deposited at 625 C. The recombination behavior of grain boundaries and intragrain defects is investigated in as-deposited and heat-treated samples.

  7. Luminescent Rhenium(I) Pyridyldiaminocarbene Complexes: Photophysics, Anion-Binding, and CO2-Capturing Properties.

    PubMed

    Ng, Chi-On; Cheng, Shun-Cheung; Chu, Wing-Kin; Tang, Kin-Man; Yiu, Shek-Man; Ko, Chi-Chiu

    2016-08-15

    A series of luminescent isocyanorhenium(I) complexes with chelating acyclic diaminocarbene ligands (N^C) has been synthesized and characterized. Two of these carbene complexes have also been structurally characterized by X-ray crystallography. These complexes show blue-to-red phosphorescence, with the emission maxima not only considerably varied with a change in the number of ancillary isocyanide ligands but also extremely sensitive to the electronic and steric nature of the substituents on the acyclic diaminocarbene ligand. A detailed study with the support of density functional theory calculations revealed that the lowest-energy absorption and phosphorescence of these complexes in a degassed CH2Cl2 solution are derived from the predominantly metal-to-ligand charge-transfer [dπ(Re) → π*(N^C)] excited state. The unprecedented anion-binding and CO2-capturing properties of the acyclic diaminocarbene have also been described. PMID:27458842

  8. Polyaniline-coated upconversion nanoparticles with upconverting luminescent and photothermal conversion properties for photothermal cancer therapy.

    PubMed

    Xing, Yadong; Li, Luoyuan; Ai, Xicheng; Fu, Limin

    2016-01-01

    In this study, we developed a nanosystem based on upconversion nanoparticles (UCNPs) coated with a layer of polyaniline nanoparticles (PANPs). The UCNP induces upconversion luminescence for imaging and photothermal conversion properties are due to PANPs. In vitro experiments showed that the UCNPs-PANPs were nontoxic to cells even at a high concentration (800 µg mL(-1)). Blood analysis and histological experiments demonstrated that the UCNPs-PANPs exhibited no apparent toxicity in mice in vivo. Besides their efficacy in photothermal cancer cell ablation, the UCNP-PANP nanosystem was found to achieve an effective in vivo tumor ablation effect after irradiation using an 808 nm laser. These results demonstrate the potential of the hybrid nanocomposites for use in imaging-guided photothermal therapy. PMID:27621625

  9. Synthesis, characterisation, optical and luminescence properties of CoAl2O4

    NASA Astrophysics Data System (ADS)

    Agilandeswari, K.; Kumar, A. Ruban

    2015-06-01

    Solid state method has been used as an efficient method to synthesize blue pigment CoAl2O4 at a temperature of 800°C. The products were characterized by powder X-ray diffraction (XRD), Fourier transformer infrared spectroscopy (FTIR), UV-Visible diffuse reflectance spectroscopy (DRS) and luminescent spectroscopy. X-ray diffraction pattern confirmed the formation of single phase CoAl2O4. Optical properties of CoAl2O4 ceramic shows an energy band gap in the range of 3.10eV. The emission spectra of spinel CoAl2O4 in the visible region confirmed the presence of tetrahedral coordinated Co2+ ions.

  10. Gamma irradiation effects on the luminescence properties of SrBPO5: Sm

    NASA Astrophysics Data System (ADS)

    Mohapatra, M.; Kumar, M.; Natarajan, V.; Godbole, S. V.

    2014-10-01

    Samarium doped SrBPO5 phosphor was synthesized by a high temperature solid state reaction route and its luminescence properties were investigated before and after gamma irradiation. A photo-acoustic spectroscopic technique was used to record the excitation/absorption spectrum of the sample. Photoluminescence studies on the sample prior to gamma irradiation confirmed the presence of Sm3+ at an asymmetric site. After 2 kGy of gamma irradiation, the sample showed strong afterglow without any external source that lasted for several minutes. Thermoluminescence (TSL) studies revealed the presence of glow peak at 323 K for the system. Electron spin resonance (ESR) studies suggested the formation of borate and oxygen based radical centers in the gamma irradiated system. Detailed ESR-TSL correlation study confirmed the destruction of the oxygen radical to be responsible for the observed glow peak. Based on the findings, a probable mechanism was proposed for the glow peak and observed afterglow.

  11. Red persistent luminescence and magnetic properties of nanomaterials for multimodal imaging

    NASA Astrophysics Data System (ADS)

    Rosticher, C.; Chanéac, C.; Viana, B.; Fortin, M. A.; Lagueux, J.; Faucher, L.

    2014-03-01

    We present a new generation of nanotracers with persistent luminescence properties in the red-near IR range for small animal imaging. Silicates, oxysulfides and calcium phosphates nanoparticles doped with transition metal and lanthanide ions were developed in this aim. We have focused our attention in this paper on the biocompatible TCP/HAp phosphate compounds doped with Eu, Mn, Dy and on the Gd2O2S:Eu, Mg, Ti materials in the form of nanoparticles. All the nanosensors were hydrothermally synthesized and if the phosphate has a very high interest due to its biocompatibility Gd2O2S:Eu, Mg, Ti was investigated as a multimodal agent for possible in vivo optical imaging and MRI imaging.

  12. Synthesis, crystal structure and luminescent property of heterometallic d10-d8 porous complex

    NASA Astrophysics Data System (ADS)

    Zhang, Mei-Li; Wang, Ji-Jiang; Chen, Xiao-Li

    2015-02-01

    One new heterometallic complex [Cd2Cu(BTC)2(H2O)2]ṡ2H2O (1) (BTC = benzene-1,3,5-tricarboxylate), has been synthesized and characterized by elemental analysis and single-crystal X-ray diffraction techniques. The structure indicates that the complex 1 crystallizes in triclinic, space group Pī, in which, the carboxylate groups of BTC ligand adopt μ2-η1:η1, and μ2-η2:η1 coordination modes, bridging Cd(II) and Cu(II) atoms to generate 2D Cd-BTC bilayer then to a (4,6)-connected open 3D framework with 1D channels occupied by guest water molecules. In addition, thermal gravimetric analysis (TGA) and luminescent property of 1 were investigated.

  13. Synthesis, characterization and luminescent properties of lanthanide complexes with a novel multipodal ligand

    NASA Astrophysics Data System (ADS)

    Yan, Zhen-Zhong; Hou, Na; Wang, Cong-Min

    2015-02-01

    Solid complexes of lanthanide nitrates with an novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2‧-furfurylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level (T1) of the ligand matches better the resonance level of Tb(III) than other lanthanide ions.

  14. Synthesis, characterization and luminescent properties of lanthanide complexes with a novel multipodal ligand.

    PubMed

    Yan, Zhen-Zhong; Hou, Na; Wang, Cong-Min

    2015-02-25

    Solid complexes of lanthanide nitrates with an novel multipodal ligand, 1,2,4,5-tetramethyl-3,6-bis{N,N-bis[((2'-furfurylaminoformyl)phenoxyl)ethyl]-aminomethyl}-benzene (L) have been synthesized and characterized by elemental analysis, infrared spectra and molar conductivity measurements. At the same time, the luminescent properties of the Sm(III), Eu(III), Tb(III) and Dy(III) nitrate complexes in solid state were investigated. Under the excitation of UV light, these complexes exhibited characteristic emission of central metal ions. The lowest triplet state energy level of the ligand indicates that the triplet state energy level (T1) of the ligand matches better the resonance level of Tb(III) than other lanthanide ions. PMID:25305620

  15. Investigation of InGaN/GaN laser degradation based on luminescence properties

    NASA Astrophysics Data System (ADS)

    Wen, Pengyan; Zhang, Shuming; Liu, Jianping; Li, Deyao; Zhang, Liqun; Sun, Qian; Tian, Aiqin; Zhou, Kun; Zhou, Taofei; Yang, Hui

    2016-06-01

    Degradation of InGaN/GaN laser diode (LD) is investigated based on the luminescence properties. Gradual degradation of the LD is presented with the threshold current increase and the slope efficiency decrease. The cathodoluminescence and photoluminescence characterizations of the LD show a dislocation independent degradation of the active region under the ridge. Detailed studies on the temperature-dependent micro-photoluminescence and the electroluminescence indicate that the degradation of the LD is attributed to the generation of non-radiative recombination centers in the local multiple quantum well regions with lower indium content. The activation energy of the non-radiative recombination centers is about 10.2 meV.

  16. Synthesis, crystal structure, and luminescence properties of a new europium silicate.

    PubMed

    Liu, Wei; Ji, Ying; Wang, Ying; Sun, Qiushi; Zhao, Xudong; Liu, Xiaoyang; Jia, Xiaopeng

    2016-06-21

    A new europium silicate, NaEuSi3O7(OH)2 (denoted as 1), was synthesized under high-temperature and high-pressure conditions, and structurally characterized by single-crystal and powder X-ray diffraction (XRD) analyses. The single-crystal XRD analysis of 1 revealed that its structure was based on SiO4 tetrahedron single chains, which were connected together by the EuO6 polyhedron via vertex oxygen atoms forming a three-dimensional framework of 1. It contained 4, 6-ring channels along the [010] direction, which were delimited by the SiO4 tetrahedron and EuO6 polyhedron. The Na(+) ions were located in the 6-ring channels along the [010] direction to achieve the charge balance. The luminescence properties of 1 were also investigated. PMID:27221581

  17. High efficiency green-luminescent LaPO 4:Ce,Tb hierarchical nanostructures: Synthesis, characterization, and luminescence properties

    NASA Astrophysics Data System (ADS)

    Fu, Zhenxiao; Bu, Wenbo

    2008-08-01

    High efficiency green-luminescent LaPO 4:Ce,Tb hierarchical nanostructures with uniform spindle shape have been successfully constructed by a simple Pluronic P123-assisted hydrothermal approach via self-assembling from single-crystalline nanowires. Their morphologies and structures were examined by scanning and transmission electron microscopy. The resulting uniform spindle-shaped microstructures are composed of several tens of aligned single-crystalline nanowires. The surfactant Pluronic P123 was found to play a crucial role in achieving uniform morphology of the final product as compared with the same material but synthesized without the surfactant Pluronic P123. These LaPO 4:Ce,Tb spindle-shaped microstructures show efficient photoluminescence which is associated with its surface smoothness, high crystallization and uniform morphologies of the micro-architectures.

  18. Structure and luminescence properties of thermally nitrided Ga{sub 2}O{sub 3} nanowires

    SciTech Connect

    Kim, Hyunsu; Jin, Changhyun; Park, Sunghoon; Lee, Wan In; Lee, Chongmu

    2013-02-15

    Graphical abstract: The as-synthesized Ga{sub 2}O{sub 3} nanowires exhibited a broad emission band at approximately 570 nm in the green region. In contrast, the thermally nitrided Ga{sub 2}O{sub 3} nanowires exhibited a much stronger emission band at approximately 455 nm in the blue region. Display Omitted Highlights: ► The structure and luminescence properties of thermally nitrided Ga{sub 2}O{sub 3} nanowires were examined. ► A uniform GaN shell layer was formed on the surface of the nanowires by thermal nitridation. ► The as-synthesized Ga{sub 2}O{sub 3} nanowires exhibited a broad yellow emission. ► The nitrided Ga{sub 2}O{sub 3} nanowires exhibited a much stronger blue emission band due to the GaN shell layer. -- Abstract: The structure and luminescence properties of thermally nitrided Ga{sub 2}O{sub 3} nanowires were examined. Transmission electron microscopy and X-ray diffraction confirmed the formation of a uniform GaN shell layer on the surface of the nanowires by thermal nitridation. The core and shell of the nitrided nanowires were monoclinic-structured single crystal Ga{sub 2}O{sub 3} and wurtzite-type hexagonal close-packed-structured single crystal GaN, respectively. The as-synthesized Ga{sub 2}O{sub 3} nanowires exhibited a broad emission band at approximately 570 nm in the yellow region. In contrast, the nitrided Ga{sub 2}O{sub 3} nanowires exhibited a much stronger emission band at approximately 455 nm in the blue region, which must originate from the newly formed GaN shell layer.

  19. Synthesis, structure and luminescence properties of lanthanide complex with a new tetrapodal ligand featuring salicylamide arms

    SciTech Connect

    Song Xueqin; Wen Xiaoguang; Liu Weisheng; Wang Daqi

    2010-01-15

    A new tetrapodal ligand 1,1,1-tetrakis{l_brace}[(2'-(2-furfurylaminoformyl))phenoxyl]methyl{r_brace}methane (L) has been prepared and their coordination chemistry with Ln{sup III} ions has been investigated. The structure of {l_brace}[Ln{sub 4}L{sub 3}(NO{sub 3}){sub 12}].H{sub 2}O{r_brace}{sub i}nfinity (Ln=Nd, Eu)] shows the binodal 4,3-connected three-dimensional interpenetration coordination polymers with topology of a (8{sup 6}){sub 3}(8{sup 3}){sub 4} notation. [DyL(NO{sub 3}){sub 3}(H{sub 2}O){sub 2}].0.5CH{sub 3}OH and [ErL(NO{sub 3}){sub 3}(H{sub 2}O) (CH{sub 3}OH)].CH{sub 3}COCH{sub 3} is a 1:1 mononuclear complex with interesting supramolecular features. The structure of [NdL(H{sub 2}O){sub 6}].3ClO{sub 4}.3H{sub 2}O is a 2:1 mononuclear complex which further self-assembled through hydrogen bond to form a three-dimensional supramolecular structures. The result presented here indicates that both subtle variation of the terminal group and counter anions can be applied in the modulation of the overall molecular structures of lanthanide complex of salicylamide derivatives due to the structure specialties of this type of ligand. The luminescence properties of the Eu{sup III} complex are also studied in detail. - Grapical Abstract: We present here a series of zero- to three-dimensional lanthanide coordination structures and luminescence properties of Eu(III) complex of a new tetrapodal ligand.

  20. Luminescence Properties of SrCaS:Cu Thin Film Phosphors

    NASA Astrophysics Data System (ADS)

    Mohammed, Edris; Park, Won; Tong, Wusheng; Stock, Stuart; Summers, Chris

    2000-03-01

    Luminescence Properties of SrxCa1-xS:Cu Thin Film Phosphors E. Mohammed, W. Park, W. Tong, S. Stock and C. J. Summers Phosphor Technology Center of Excellence Georgia Institute of Technology, Atlanta, GA 30332-0560 The luminescence properties of MBE grown thin film SrCaS:Cu phosphors are investigated. 10K photoluminescence (PL) results showed a broad emission band of Cu that shifted between 2.98eV and 2.58eV, with a large increase in linewidth ranging from 0.36eV for CaS:Cu to 0.49eV as the Sr composition was increased. The significant increase in linewidth suggested that the broad emission band of Cu was composed of two closely spaced bands suggesting a possible spin-orbit or Jahn-Teller splitting of the emitting level. Curve fitting of the 10K PL showed that the splitting varied from 100meV for x=0 to 240 meV for x=0.98. In the excitation spectra, the optical absorption edge shifted from 5.1eV to 4.7eV while the energies of the two direct excitation bands of Cu shifted from 4.4 to 4.8eV and 4.0 to 4.2eV respectively. The crystal field parameter 10Dq obtained from experiments showed a linear as the composition of Sr was varied between x=0 to x=0.98 and the result was in excellent agreement with crystal field calculations.

  1. High resolution shallow geologic characterization of a late Pleistocene eolian environment using ground penetrating radar and optically stimulated luminescence techniques: North Carolina, USA

    USGS Publications Warehouse

    Mallinson, D.; Mahan, S.; Moore, Christine

    2008-01-01

    Geophysical surveys, sedimentology, and optically-stimulated luminescence age analyses were used to assess the geologic development of a coastal system near Swansboro, NC. This area is a significant Woodland Period Native American habitation and is designated the "Broad Reach" archaeological site. 2-d and 3-d subsurface geophysical surveys were performed using a ground penetrating radar system to define the stratigraphic framework and depositional facies. Sediment samples were collected and analyzed for grain-size to determine depositional environments. Samples were acquired and analyzed using optically stimulated luminescence techniques to derive the depositional age of the various features. The data support a low eolian to shallow subtidal coastal depositional setting for this area. Li-DAR data reveal ridge and swale topography, most likely related to beach ridges, and eolian features including low-relief, low-angle transverse and parabolic dunes, blowouts, and a low-relief eolian sand sheet. Geophysical data reveal dominantly seaward dipping units, and low-angle mounded features. Sedimentological data reveal mostly moderately-well to well-sorted fine-grained symmetrical to coarse skewed sands, suggesting initial aqueous transport and deposition, followed by eolian reworking and bioturbation. OSL data indicate initial coastal deposition prior to ca. 45,000 yBP, followed by eolian reworking and low dune stabilization at ca. 13,000 to 11,500 yBP, and again at ca. 10,000 yBP (during, and slightly after the Younger Dryas chronozone).

  2. Impact of firing on the OSL luminescence properties of natural quartz: A case study

    NASA Astrophysics Data System (ADS)

    Koul, D. K.; Polymeris, G. S.; Soni, A.; Kulkarni, M. S.

    2016-03-01

    A comprehensive study was carried out to observe the impact of firing on the behavior of different features of the optically stimulated luminescence (OSL) signal of geological quartz. The different features which could influence its use in different applications were studied. A comparison of nature of (i) thermoluminescence (TL) glow curves, (ii) OSL decay curves, (iii) pulse annealing curves, (iv) fast and slow components and (v) thermally transferred OSL (TT-OSL) emission of unfired and fired samples suggested a profound influence of thermal firing on the OSL signal. The composition of the OSL signal was seen to get altered by firing treatment; the magnitude of slow component losing its dominance to the fast component. This was true of pulse annealing also, the fired curve looked different from the unfired one. TT-OSL was observed to be larger in unfired sample as compared to the fired sample. Finally, firing was seen to enable reliable dose recovery using single aliquot regenerative (SAR) method, which has not been the case with the unfired sample studied here.

  3. Stored luminescence computed tomography.

    PubMed

    Cong, Wenxiang; Wang, Chao; Wang, Ge

    2014-09-01

    Phosphor nanoparticles made of doped semiconductors and pre-excited by x-ray radiation were recently reported for their luminescence emission in the range of 650-770 nm upon near-infrared (NIR) light stimulation. These nanophosphors can be functionalized as optical probes for molecular imaging. In this paper, we present stored luminescence computed tomography to reconstruct a nanophosphor distribution in an object. The propagation of x rays in a biological object allows significantly better localization and deeper penetration. Moreover, the nanophosphors, which are pre-excited with collimated x-ray beams or focused x-ray waves, can be successively stimulated for stored luminescence emissions by variable NIR stimulation patterns. The sequentially detected luminescence signals provide more information of a nanophosphor spatial distribution for more accurate image reconstruction and higher image resolution. A realistic numerical study is performed to demonstrate the feasibility and merits of the proposed approach. PMID:25321362

  4. Relative optically stimulated luminescence and thermoluminescence efficiencies of Al{sub 2}O{sub 3}:C dosimeters to heavy charged particles with energies relevant to space and radiotherapy dosimetry

    SciTech Connect

    Sawakuchi, G. O.; Yukihara, E. G.; McKeever, S. W. S.; Benton, E. R.; Gaza, R.; Uchihori, Y.; Yasuda, N.; Kitamura, H.

    2008-12-15

    This article presents a comprehensive characterization of the thermoluminescence (TL) and optically stimulated luminescence (OSL) relative luminescence efficiencies of carbon-doped aluminum (Al{sub 2}O{sub 3}:C) for heavy charged particles (HCPs) with atomic numbers ranging from 1 (proton) to 54 (xenon) and energies ranging from 7 to 1000 MeV/u, and investigates the dependence of the Al{sub 2}O{sub 3}:C response on experimental conditions. Relative luminescence efficiency values are presented for 19 primary charge/energy combinations, plus 31 additional charge/energy combinations obtained by introducing absorbers in the primary beam. Our results show that for energies of hundreds of MeV/u the data can be described by a single curve of relative luminescence efficiency versus linear energy transfer (LET). This information is needed to compensate for the reduced OSL efficiency to high-LET particles in such applications as space dosimetry. For lower energies, the relative luminescence efficiency as function of LET cannot be described by a single curve; instead, it separates into different components corresponding to different particles. We also present data on the low-LET dose response of Al{sub 2}O{sub 3}:C, measured under the same experimental conditions in which the relative luminescence efficiencies to HCPs were obtained, providing information relevant to future theoretical investigations of HCP energy deposition and luminescence production in Al{sub 2}O{sub 3}:C.

  5. Luminescence properties of monoclinic Cu{sub 4}I{sub 4}(Piperidine){sub 4}

    SciTech Connect

    Jalilian, Ehsan; Liao, Rong-Zhen; Himo, Fahmi; Lidin, Sven

    2011-08-15

    Highlights: {yields} A new modification of Cu{sub 4}I{sub 4}Pip{sub 4} has been produced under hydrothermal conditions. {yields} This modification have fluorescence properties when it is exposed to UV light. {yields} The fluorescence properties was characterized with fluorescence spectrophotometer. {yields} Quantum mechanical calculations was also performed. -- Abstract: A new modification of Cu{sub 4}I{sub 4}Pip{sub 4} has been synthesized under hydrothermal conditions. X-ray crystallography revealed that this compound crystallized in the monoclinic system and consists of a tetrahedral core with composition Cu{sub 4}I{sub 4}, in which each Cu atom is coordinated by a piperidine molecule via the N atom. In contrast to a previously reported modification of Cu{sub 4}I{sub 4}Pip{sub 4}, the present modification shows luminescent properties when exposed to UV-light. In addition, we have used time-dependent density functional theory calculations to characterize both compounds in term of both absorption and emission.

  6. Luminescence properties of phosphate phosphor Ba3Y(PO4)3:Sm3+

    NASA Astrophysics Data System (ADS)

    Yang, Fu; Liu, Yufeng; Tian, Xiaodong; Dong, Guoyi; Yu, Quanmao

    2015-05-01

    A series of reddish orange-emitting phosphate phosphors Ba3Y1-x(PO4)3:xSm3+(0.01≤x≤0.20) were synthesized by solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of as-synthesized phosphors. The optimized phosphors Ba3Y0.95(PO4)3:0.05Sm3+ present several excitation bands from 300 to 500 nm, and exhibit intense reddish orange-emitting properties. The energy transfer type between Sm3+ ions was confirmed as d-d interaction by using Van Uitert model. The chromatic properties of the typical sample Ba3Y(PO4)3:0.05Sm3+ phosphor have been found to have chromaticity coordinates of (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. These results indicated that Ba3Y(PO4)3:Sm3+ phosphors have potential applications in the field of lighting and display due to their effective excitation in the near-ultraviolet range.

  7. The response of thermally and optically stimulated luminescence from Al2O3:C to high-energy heavy charged particles

    NASA Technical Reports Server (NTRS)

    Gaza, R.; Yukihara, E. G.; McKeever, S. W. S.

    2004-01-01

    The thermoluminescence (TL) and optically stimulated luminescence (OSL) response of Al2O3 dosimeters to high-energy heavy charged particles (HCP) has been studied using the heavy ion medical accelerator at Chiba, Japan. The samples were Al2O3 single-crystal chips, of the type usually known as TLD-500, and Luxel(TM) dosimeters (Al2O3:C powder in plastic) from Landauer Inc. The samples were exposed to 4He (150 MeV/u), 12C (400 MeV/u), 28Si (490 MeV/us) and 56Fe (500 MeV/u) ions, with linear energy transfer values covering the range from 2.26 to 189 keV/micrometers in water and doses from 1 to 100 mGy (to water). A 90Sr/90Y beta source, calibrated against a 60Co secondary standard, was used for calibration purposes. For OSL, we used both continuous-wave OSL measurements (CW-OSL, using green light stimulation at 525 nm) and pulsed OSL measurements (POSL, using 532 nm stimulation from a Nd:YAG Q-switched laser). The efficiencies (eta HCP, gamma) of the different HCPs at producing OSL or TL were observed to depend not only upon the linear energy transfer (LET) of the HCP, but also upon the sample type (single crystal chip or Luxel(TM)) and the luminescence method used to define the signal--i.e. TL, CW-OSL initial intensity, CW-OSL total area, or POSL. Observed changes in shape of the decay curve lead to potential methods for extracting LET information of unknown radiation fields. A discussion of the results is given, including the potential use of OSL from Al2O3 in the areas of space radiation dosimetry and radiation oncology. c2004 Elsevier Ltd. All rights reserved.

  8. The response of thermally and optically stimulated luminescence from Al2O3:C to high-energy heavy charged particles.

    PubMed

    Gaza, R; Yukihara, E G; McKeever, S W S

    2004-01-01

    The thermoluminescence (TL) and optically stimulated luminescence (OSL) response of Al2O3 dosimeters to high-energy heavy charged particles (HCP) has been studied using the heavy ion medical accelerator at Chiba, Japan. The samples were Al2O3 single-crystal chips, of the type usually known as TLD-500, and Luxel(TM) dosimeters (Al2O3:C powder in plastic) from Landauer Inc. The samples were exposed to 4He (150 MeV/u), 12C (400 MeV/u), 28Si (490 MeV/us) and 56Fe (500 MeV/u) ions, with linear energy transfer values covering the range from 2.26 to 189 keV/micrometers in water and doses from 1 to 100 mGy (to water). A 90Sr/90Y beta source, calibrated against a 60Co secondary standard, was used for calibration purposes. For OSL, we used both continuous-wave OSL measurements (CW-OSL, using green light stimulation at 525 nm) and pulsed OSL measurements (POSL, using 532 nm stimulation from a Nd:YAG Q-switched laser). The efficiencies (eta HCP, gamma) of the different HCPs at producing OSL or TL were observed to depend not only upon the linear energy transfer (LET) of the HCP, but also upon the sample type (single crystal chip or Luxel(TM)) and the luminescence method used to define the signal--i.e. TL, CW-OSL initial intensity, CW-OSL total area, or POSL. Observed changes in shape of the decay curve lead to potential methods for extracting LET information of unknown radiation fields. A discussion of the results is given, including the potential use of OSL from Al2O3 in the areas of space radiation dosimetry and radiation oncology. PMID:15856574

  9. SU-E-CAMPUS-T-05: Preliminary Results On a 2D Dosimetry System Based On the Optically Stimulated Luminescence of Al2O3

    SciTech Connect

    Ahmed, M; Eller, S; Yukihara, E; Schnell, E; Ahmad, S; Akselrod, M; Hanson, O

    2014-06-15

    Purpose: To develop a precise 2D dose mapping technique based on the optically stimulated luminescence (OSL) from Al{sub 2}O{sub 3} films for medical applications. Methods: A 2D laser scanning reader was developed using fast F{sup +}-center (lifetime of <7 ns) and slow F-center (lifetime of 35 ms) OSL emission from newly developed Al{sub 2}O{sub 3} films (Landauer Inc.). An algorithm was developed to correct images for both material and system properties. Since greater contribution of the F??-center emission in the recorded signal increases the readout efficiency and robustness of image corrections, Al{sub 2}O{sub 3}:C,Mg film samples are being investigated in addition to Al{sub 2}O{sub 3}:C samples. Preliminary investigations include exposure of the films to a 6 MV photon beam at 10 cm depth in solid water phantom with an SSD of 100 cm, using a 10 cm × 10 cm flat field or a 4 cm × 4 cm field with a 60° wedge filter. Kodak EDR2 radiographic film and EBT2 Gafchromic film were also exposed for comparison. Results: The results indicate that the algorithm is able to correct images and calculate 2D dose. For the wedge field irradiation, the calculated dose at the center of the field was 0.9 Gy for Al{sub 2}O{sub 3}:C and 0.87 Gy for Al{sub 2}O{sub 3}:C,Mg, whereas, the delivered dose was 0.95 Gy. A good qualitative agreement of the dose profiles was obtained between the OSL films and EDR2 and EBT2 films. Laboratory tests using a beta source suggest that a large dynamic range (10{sup −2}−10{sup 2} Gy) can be achieved using this technique. Conclusion: A 2D dosimetry system and an in-house image correction algorithm were developed for 2D film dosimetry in medical applications. The system is in the preliminary stage of development, but the data demonstrates the feasibility of this approach. This work was supported by Landauer, Inc.

  10. Enhanced UV Emission From Silver/ZnO And Gold/ZnO Core-Shell Nanoparticles: Photoluminescence, Radioluminescence, And Optically Stimulated Luminescence

    NASA Astrophysics Data System (ADS)

    Guidelli, E. J.; Baffa, O.; Clarke, D. R.

    2015-09-01

    The optical properties of core-shell nanoparticles consisting of a ZnO shell grown on Ag and Au nanoparticle cores by a solution method have been investigated. Both the ZnO/Ag and ZnO/Au particles exhibit strongly enhanced near-band-edge UV emission from the ZnO when excited at 325 nm. Furthermore, the UV intensity increases with the metal nanoparticle concentration, with 60-fold and 17-fold enhancements for the ZnO/Ag and ZnO/Au, core-shell nanoparticles respectively. Accompanying the increase in UV emission, there is a corresponding decrease in the broad band defect emission with nanoparticle concentration. Nonetheless, the broad band luminescence increases with laser power. The results are consistent with enhanced exciton emission in the ZnO shells due to coupling with surface plasmon resonance of the metal nanoparticles. Luminescence measurements during and after exposure to X-rays also exhibit enhanced UV luminescence. These observations suggest that metal nanoparticles may be suitable for enhancing optical detection of ionizing radiation.

  11. Enhanced UV Emission From Silver/ZnO And Gold/ZnO Core-Shell Nanoparticles: Photoluminescence, Radioluminescence, And Optically Stimulated Luminescence.

    PubMed

    Guidelli, E J; Baffa, O; Clarke, D R

    2015-01-01

    The optical properties of core-shell nanoparticles consisting of a ZnO shell grown on Ag and Au nanoparticle cores by a solution method have been investigated. Both the ZnO/Ag and ZnO/Au particles exhibit strongly enhanced near-band-edge UV emission from the ZnO when excited at 325 nm. Furthermore, the UV intensity increases with the metal nanoparticle concentration, with 60-fold and 17-fold enhancements for the ZnO/Ag and ZnO/Au, core-shell nanoparticles respectively. Accompanying the increase in UV emission, there is a corresponding decrease in the broad band defect emission with nanoparticle concentration. Nonetheless, the broad band luminescence increases with laser power. The results are consistent with enhanced exciton emission in the ZnO shells due to coupling with surface plasmon resonance of the metal nanoparticles. Luminescence measurements during and after exposure to X-rays also exhibit enhanced UV luminescence. These observations suggest that metal nanoparticles may be suitable for enhancing optical detection of ionizing radiation. PMID:26365945

  12. Luminescent properties of lithium-phosphate-borate glasses doped with Tb3+/ Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Valiev, D. T.; Stepanov, S. A.; Cong, Liu

    2016-02-01

    The luminescence of Li2O-B2O3-P2O5-CaF2 scintillation glass doped Tb3+, Eu3+ under different types of excitation sources are investigated. Changing the europium concentration of 0.5 to 1 wt% leads changes in luminescence intensity of Tb3+ ions. The luminescence spectrum of the Tb3+ ions are depend on the concentration of Eu3+. It was found, that the luminescence decay kinetics of terbium ion in the band 543 nm depending on the concentration of europium and from type of excitation. The difference in the nature of the luminescence decay kinetics of glasses under pulsed photo- and electronic excitation discussed.

  13. Swift heavy ion induced modifications of luminescence and mechanical properties of polypropylene/ZnO nanocomposites

    NASA Astrophysics Data System (ADS)

    Maniks, J.; Grigorjeva, L.; Zabels, R.; Millers, D.; Bochkov, I.; Zicans, J.; Ivanova, T.; Grabis, J.

    2014-05-01

    The effect of irradiation with 150 MeV Kr ions at fluencies 1011 and 1012 ions/cm2 on luminescence of PP/ZnO nanocomposites and PP matrix has been studied. In unirradiated composite the luminescence is comparatively weak and is contributed mainly by the excitonic luminescence of ZnO. Irradiation of nanocomposite and PP matrix leads to a strong increase of luminescence intensity in a wide spectral range of 360-600 nm. It follows from the obtained results that the enhancement of luminescence originates mainly from the broken bonds in PP matrix. Ion-induced scission of polymer bonds and fragmentation of polymer chains is deduced also from the nanoindentation tests which show a remarkable reduction of hardness for the irradiated samples.

  14. Mutifuntional GdPO4:Eu3+ hollow spheres: synthesis and magnetic and luminescent properties.

    PubMed

    Zhang, Lihui; Yin, Meili; You, Hongpeng; Yang, Mei; Song, Yanhua; Huang, Yeju

    2011-11-01

    Mondispersed submicrometer GdPO(4):Eu(3+) hollow spheres were synthesized via an effective one-pot hydrothermal process. These hollow spheres have the average diameter of 200 nm, and the shell thickness is about 20 nm. The surface of the spheres consists of a number of nanorods with diameters of about 10 nm and lengths of about 50-80 nm. Both magnetic and luminescent properties of the obtained Eu(3+)-doped GdPO(4) hollow spheres were investigated. The hysteresis plot (M-H) analysis result indicates their paramagnetic property. The fluorescence spectra demonstrate that they emit orange-red color light originated from the (5)D(0) → (7)F(J) transitions of the Eu(3+) ions. Therefore, the obtained GdPO(4) hollow spheres hold promise for encapsulate drugs with controlled release. Moreover, the GdPO(4):Eu(3+) hollow spheres are attributes for bimodal magnetic resonance imaging (MRI)/optical bioimaging labeling. PMID:21970439

  15. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties

    NASA Astrophysics Data System (ADS)

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-Gai; Wu, Xiaowen; Zhang, Shaowei

    2016-03-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties.

  16. Structural, magnetic and luminescent properties of lanthanide complexes with N-salicylideneglycine.

    PubMed

    Vančo, Ján; Trávníček, Zdeněk; Kozák, Ondřej; Boča, Roman

    2015-01-01

    A series of anionic heavy lanthanide complexes, involving the N-salicylideneglycinato(2-) Schiff base ligand (salgly) and having the general formula K[Ln(salgly)₂(H₂O)₂]∙H₂O (1-6), where Ln stands for Gd, Tb, Dy, Ho, Er and Tm, was prepared using the one-pot template synthesis. The complexes were thoroughly characterized by elemental and Thermogravimetric/Differential Thermal Analyses (TG/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), and photoluminescence spectroscopies, electrospray-ionization mass spectrometry, and their magnetic properties were studied by temperature-dependent dc magnetic measurements using the superconducting quantum interference device (SQUID). The X-ray structure of the terbium(III) complex (2), representing the unique structure between the lanthanide complexes of N-salicylideneamino acids, was determined. The results of spectral and structural studies revealed the isostructural nature of the prepared complexes, in which the lanthanide ion is octacoordinated by two O,N,O-donor salgly ligands and two aqua ligands. The analysis of magnetic data confirmed that the complexes behave as paramagnets obeying the Curie law. The results of photoluminescence spectral studies of the complexes showed the different origin in their luminescent properties between the solid state and solution. An antenna effect of the Schiff base ligand was observed in a powder form of the complex only, while it acts as a fluorophore in a solution. PMID:25927576

  17. Structural, Magnetic and Luminescent Properties of Lanthanide Complexes with N-Salicylideneglycine

    PubMed Central

    Vančo, Ján; Trávníček, Zdeněk; Kozák, Ondřej; Boča, Roman

    2015-01-01

    A series of anionic heavy lanthanide complexes, involving the N-salicylideneglycinato(2-) Schiff base ligand (salgly) and having the general formula K[Ln(salgly)2(H2O)2]∙H2O (1–6), where Ln stands for Gd, Tb, Dy, Ho, Er and Tm, was prepared using the one-pot template synthesis. The complexes were thoroughly characterized by elemental and Thermogravimetric/Differential Thermal Analyses (TG/DTA), Fourier Transform Infrared Spectroscopy (FT-IR), and photoluminescence spectroscopies, electrospray-ionization mass spectrometry, and their magnetic properties were studied by temperature-dependent dc magnetic measurements using the superconducting quantum interference device (SQUID). The X-ray structure of the terbium(III) complex (2), representing the unique structure between the lanthanide complexes of N-salicylideneamino acids, was determined. The results of spectral and structural studies revealed the isostructural nature of the prepared complexes, in which the lanthanide ion is octacoordinated by two O,N,O-donor salgly ligands and two aqua ligands. The analysis of magnetic data confirmed that the complexes behave as paramagnets obeying the Curie law. The results of photoluminescence spectral studies of the complexes showed the different origin in their luminescent properties between the solid state and solution. An antenna effect of the Schiff base ligand was observed in a powder form of the complex only, while it acts as a fluorophore in a solution. PMID:25927576

  18. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties.

    PubMed

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-Gai; Wu, Xiaowen; Zhang, Shaowei

    2016-01-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties. PMID:26940294

  19. Morphology controlling method for amorphous silica nanoparticles and jellyfish-like nanowires and their luminescence properties

    PubMed Central

    Liu, Haitao; Huang, Zhaohui; Huang, Juntong; Xu, Song; Fang, Minghao; Liu, Yan-gai; Wu, Xiaowen; Zhang, Shaowei

    2016-01-01

    Uniform silica nanoparticles and jellyfish-like nanowires were synthesized by a chemical vapour deposition method on Si substrates treated without and with Ni(NO3)2, using silicon powder as the source material. Composition and structural characterization using field emission scanning electron microscopy, transmission electron microscopy, energy dispersive X-ray spectroscopy and fourier-transform infrared spectroscopy showed that the as-prepared products were silica nanoparticles and nanowires which have amorphous structures. The form of nanoparticles should be related to gas-phase nucleation procedure. The growth of the nanowires was in accordance with vapour-liquid-solid mechanism, followed by Ostwald ripening to form the jellyfish-like morphology. Photoluminescence and cathodoluminescence measurements showed that the silica products excited by different light sources show different luminescence properties. The emission spectra of both silica nanoparticles and nanowires are due to the neutral oxygen vacancies (≡Si-Si≡). The as-synthesized silica with controlled morphology can find potential applications in future nanodevices with tailorable photoelectric properties. PMID:26940294

  20. Synthesis and luminescent properties of ternary complex Eu(UVA)3Phen in nano-TiO2

    NASA Astrophysics Data System (ADS)

    Lü, Yu-guang; Gong, Zhong-ping; Gao, Hong-bing; Zhou, Shu-jing; Lü, Kui-lin; Wang, Ying; A, Du; Du, Hao-ran; Zhang, Li; Zhang, Fu-jun

    2015-01-01

    By introducing 2-hydroxy-4-methoxy-benzophenone (UVA) and 1,10-phenanthroline (Phen) as the ligands, the ternary rare earth complex of Eu(UVA)3Phen is synthesized, and it is characterized by elemental analysis, mass spectra (MS) and infrared (IR) and ultraviolet (UV) spectroscopy. Results show that the Eu(III) in complex emits strong red luminescence when it is excited by UV light, and it has higher sensitized luminescent efficiency and longer lifetime. The organic-inorganic thin film of complex Eu(UVA)3Phen doped with nano-TiO2 is prepared, and the nano-TiO2 is used in the luminescence layer to change the luminescence property of Eu(UVA)3Phen. It is found that there is an efficient energy transfer process between ligands and metal ions. Moreover, in an indium tin oxide (ITO)/poly(N-vinylcar-bazole) (PVK)/Eu(UVA)3Phen/Al device, Eu3+ can be excited by intramolecular ligand-to-metal energy transfer process. The main peak of emission at 613 nm is attributed to 5D0→7F2 transition of the Eu3+, and this process results in the enhanced red emission.

  1. The influence of silver-ion doping using ion implantation on the luminescence properties of Er-Yb silicate glasses

    NASA Astrophysics Data System (ADS)

    Stanek, S.; Nekvindova, P.; Svecova, B.; Vytykacova, S.; Mika, M.; Oswald, J.; Mackova, A.; Malinsky, P.; Spirkova, J.

    2016-03-01

    A set of zinc-silicate glasses with different ratios of erbium and ytterbium was fabricated. To achieve Ag-rich thin films in a sub-surface layer, ion-implantation technique at an energy of 1.2 MeV and 1.7 MeV with a fluence of 1 × 1016 cm-2 was used. Post-implantation annealing was also applied. Changes in the spectroscopic and lasing properties of erbium ions as a function of implantation fluence of silver were studied with the aim to assess the positive effect of silver as a sensitiser of erbium luminescence. Therefore, absorption spectra in the visible range as well as luminescence spectra in the near-infrared range were measured and partially also the 4I11/2-4I15/2 transition of the erbium ion was studied. The results showed that silver positively influenced luminescence intensity at 1530 nm by increasing it almost three times. The biggest increase was achieved in glass with the highest concentration of erbium. Luminescence lifetime was not significantly influenced by the presence of silver and still remained around 10 ms.

  2. Luminescence properties and electronic structure of Ce{sup 3+}-doped gadolinium aluminum garnet

    SciTech Connect

    Dotsenko, V.P.; Berezovskaya, I.V.; Voloshinovskii, A.S.; Zadneprovski, B.I.; Efryushina, N.P.

    2015-04-15

    Highlights: • The luminescence properties of Ce{sup 3+} ions in (Y, Gd){sub 3}Al{sub 5}O{sub 12} are analyzed. • The Gd{sup 3+} → Y{sup 3+} substitution leads to increasing of Ce{sup 3+} noncubic crystal field splitting parameter. • The excitation spectra for the Ce{sup 3+} emission in GdAG contain bands at 6.67, 7.75, and 9.76 eV. • These features are due to the Ce{sup 3+}-bound exciton formation and O 2p → Al 3s, 3p transitions. • Contributions from Al atoms to the conduction-band density of states are quite essential. - Abstract: Yttrium-gadolinium aluminum garnets (YGdAG) doped with Ce{sup 3+} ions have been prepared by co-precipitation method. The luminescent properties of Ce{sup 3+} ions in Gd{sub 3(1−x)}Ce{sub 3x}Al{sub 5}O{sub 12} (x = 0.01) have been studied upon excitation in the 2–20 eV region. The substitution of Gd{sup 3+} for Y{sup 3+} in the garnet structure results in broadening the emission band and shifting its maximum towards the longer wavelengths. It was found that in addition to the 4f → 5d excitation bands of Ce{sup 3+} ions, the excitation spectra for the Ce{sup 3+} emission contain bands at 6.67, 7.75, and 9.76 eV. These bands are attributed to the Ce{sup 3+}-bound exciton formation and O 2p → Al 3s, 3p transitions, respectively. Although gadolinium states dominate near the bottom of the conduction band of Gd{sub 3}Al{sub 5}O{sub 12}, contributions from Al{sub tetr} and Al{sub oct} atoms to the conduction-band density of states are evaluated as quite essential.

  3. Effects of growth altitude on chemical constituents and delayed luminescence properties in medicinal rhubarb.

    PubMed

    Sun, Mengmeng; Li, Li; Wang, Mei; van Wijk, Eduard; He, Min; van Wijk, Roeland; Koval, Slavik; Hankemeier, Thomas; van der Greef, Jan; Wei, Shengli

    2016-09-01

    To improve the quality control of herbal drugs, there has been a major shift from evaluating individual chemicals to evaluating multiple-constituent chemicals, given the multi-pharmacology nature of herbal drugs. Therefore, rapid, systematic assays are needed in order to assess the quality of medicinal herbs using a comprehensive, integrated approach. Light-induced delayed luminescence (DL) is used to measure decaying long-term ultra-weak photon emissions following excitation with light. DL is considered to be a sensitive indicator for characterizing the properties of biological systems and herbal medicines with various therapeutic properties. The aim of this study was to examine the feasibility of using DL as a novel quality-assessment tool using rhubarb material as a model system, and to establish the correlation between DL parameters and the chemical constituents of rhubarb. Raw roots and rhizomes were collected from rhubarb (Rheum palmatum L.) at various elevations in western China. HPLC analysis was used to identify fourteen bioactive constituents. Five DL parameters were calculated from the DL decay curves of the rhubarb samples. Statistical tools, including principal component analysis, were used to classify the rhubarb samples using data obtained using two different assays. Finally, Spearman's correlation coefficient was calculated to quantify the correlation between the bioactive compounds and corresponding DL parameters. We found that both the chemical analysis and DL measurements reflect variations in the quality of rhubarb due to environment factor. The DL parameters were correlated significantly with the bioactive chemical constituents. Our results indicate that DL is a promising tool for evaluating multiple constituents and for assessing the therapeutic properties of herbal medicines. Thus, DL may be used as part of a comprehensive system for assessing the quality and/or therapeutic properties of herbal medicines. PMID:27327125

  4. The Upconversion Luminescence Properties of Er3+/Tm3+, Yb3+-Codoped Cubic BaLiF3.

    PubMed

    Qiang, Qinping; Guo, Linna; Han, Lili; Wang, Yuhua

    2016-04-01

    Cubic BaLiF3 samples were prepared using a facile surfactant-assisted hydrothermal-microemulsion method. The samples were characterized by X-ray Diffraction (XRD) and Scanning Electron Microscopy (SEM). The upconversion luminescence (UCL) properties of the Er3+/Tm3+, Yb3+- codoped BaLiF3 samples were measured under a 980 nm excitation wavelength. Moreover, the effects of varying the concentration of Li+ ions on the luminescence properties of Er3+, Yb3+ codoped BaLiF3 were also investigated. The Tm3+, Yb3+ codoped BaLiF3 samples displayed multi-color emissions. This behavior can be explained by the pump power dependence of the upconversion emissions and the energy levels diagram. PMID:27451695

  5. Effect of irradiation on the luminescence properties of low-dimensional SiGe/Si(001) heterostructures

    SciTech Connect

    Novikov, A. V. Yablonskiy, A. N.; Platonov, V. V.; Obolenskiy, S. V.; Lobanov, D. N.; Krasilnik, Z. F.

    2010-03-15

    This study is concerned with the effect of irradiation on the luminescence properties of low-dimensional Si/Ge heterostructures with different degrees of spatial localization of charge carriers. It is shown that the radiation stability of Si/Ge heterostructures is improved with increasing efficiency of localization of charge carriers in the structures. The spatial localization of charge carriers in the SiGe nanostructures decreases the probability of nonradiative recombination of charge carriers at radiation defects produced in the Si matrix. It is demonstrated that, among the structures explored in the study, the highest radiation stability of luminescence properties is inherent in the multilayered structures containing self-assembled Ge(Si) nanoislands, in which the most efficient spatial localization of charge carriers is attained. In this case, the localization is three- and two-dimensional, correspondingly, for holes in the islands and for electrons in the Si layers that separate neighboring layers containing the islands.

  6. Dating human occupation at Toca do Serrote das Moendas, São Raimundo Nonato, Piauí-Brasil by electron spin resonance and optically stimulated luminescence.

    PubMed

    Kinoshita, Angela; Skinner, Anne R; Guidon, Niede; Ignacio, Elaine; Felice, Gisele Daltrini; Buco, Cristiane de A; Tatumi, Sonia; Yee, Márcio; Figueiredo, Ana Maria Graciano; Baffa, Oswaldo

    2014-12-01

    Excavation of Toca do Serrote das Moendas, in Piauí state, Brazil revealed a great quantity of fossil wild fauna associated with human remains. In particular, fossils of a cervid (Blastocerus dichotomus) were found, an animal frequently pictured in ancient rock wall paintings. In a well-defined stratum, two loose teeth of this species were found in close proximity to human bones. The teeth were independently dated by electron spin resonance (ESR) in two laboratories. The ages obtained for the teeth were 29 ± 3 ka (thousands of years) and 24 ± 1 ka. The concretion layer capping this stratum was dated by optically stimulated luminescence (OSL) of the quartz grains to 21 ± 3 ka. As these values were derived independently in three different laboratories, using different methods and equipment, these results are compelling evidence of early habitation in this area. PMID:25456825

  7. Luminescence properties of Tm3+/Yb3+ codoped lead alumina bismuth borate glasses

    NASA Astrophysics Data System (ADS)

    Goud, K. Krishna Murthy; Reddy, M. Chandra Shekhar; Rao, B. Appa

    2016-05-01

    This paper reports on the spectroscopic properties of Yb3+ and Tm3+ codoped lead alumina bismuth borate glasses. Optical absorption spectra of these Samples were recorded at room temperature in the wavelength range 350-2000 nm. The absorption spectra exhibited the bands at 658 nm (3H6→3F2), 686 nm (3H6→3F3), 792 nm (3H6→3H4), 1211 nm (3H6→3H5) and 1663 nm (3H6→3F4) due to Tm3+ ions. The band at 977 nm (2F7/2→2F5/2) is due to Yb3+ ions. Optical band gap (Eopt) and Urbach energy (ΔE) values were calculated from the spectra. It was observed that the value of optical band gap decreases with increase in the concentration of Tm3+ ions. The upconversion luminescence spectra were measured under excitation of 980 nm laser diode, and the intense blue (470 nm) and green (656 nm) emission were simultaneously observed at room temperature. A proposed upconversion mechanism involving energy transfer from Yb3+ to Tm3+ has been presented.

  8. Luminescence and scintillation properties of Lu3Al5O12 nanoceramics sintered by SPS method

    NASA Astrophysics Data System (ADS)

    Pejchal, Jan; Babin, Vladimir; Beitlerova, Alena; Kucerkova, Romana; Panek, Dalibor; Barta, Jan; Cuba, Vaclav; Yamaji, Akihiro; Kurosawa, Shunsuke; Mihokova, Eva; Ito, Akihiko; Goto, Takashi; Nikl, Martin; Yoshikawa, Akira

    2016-03-01

    Ce-doped lutetium aluminum garnet Lu3Al5O12 (LuAG) nanoceramics were fabricated at 1600 °C and 1700 °C by spark-plasma sintering (SPS) method from nano-powders prepared by radiation synthesis. Both undoped and Ce-doped LuAG ceramic samples were also prepared from the nano-powders at 1700 °C with significantly increased pre-heating rate. The backscattered electron images revealed large amount of pores in all the Ce-doped samples causing their significant opacity. On the other hand, very large grains and no pores were revealed in the undoped sample, which was the only transparent one. The radioluminescence measurements revealed superior overall scintillation efficiency of the samples sintered at the temperature 1700 °C, and their defect emission in the UV region was ascribed to oxygen-vacancy-related defects such as F+ centers. The photoluminescence decay of the defect emission was characterized by an extremely fast decay time of a few nanoseconds. Influence of sintering procedure and subsequent annealing on the luminescence and scintillation properties is discussed.

  9. Luminescence properties of rare earth doped metal oxide nanostructures: A case of Eu-ZnO

    NASA Astrophysics Data System (ADS)

    Sahu, D.; Acharya, B. S.; Panda, N. R.

    2016-05-01

    The present study reports the growth and luminescence properties of Eu doped ZnO nanostructures. The experiment has been carried out by synthesizing the materials by simple wet-chemical method. X-ray diffraction (XRD) studies show expansion of ZnO lattice with the incorporation of Eu ions which has been confirmed from the appearance of Eu2O3 as a minor phase in the XRD pattern. The estimation of crystallite size from XRD results matches closely with the results obtained from transmission electron microscopy. Further, these results show the formation of nanosized Eu-ZnO particles of average size around 60 nm stacked on each other. FTIR studies show the presence of both Zn-O and Eu-O modes in the spectra supporting the results obtained from XRD. The interesting results obtained from photoluminescence (PL) measurements show the presence of both band edge emission in UV region and the defect emissions in violet, blue and green region. The appearance of 5D0→7FJ transitions of Eu3+ ions in red region clearly suggests the possible occurrence of energy transfer between the energy states of ZnO host and Eu3+ ions.

  10. Synthesis and the luminescent properties of europium-activated Ca 2SnO 4 phosphors

    NASA Astrophysics Data System (ADS)

    Chen, Yu-Chung; Chang, Yen-Hwei; Tsai, Bin-Siang

    2005-12-01

    The synthesis and photoluminescent (PL) properties of calcium stannate crystals doped with europium grown by mechanically activated in a high energy vibro-mill have been investigated. The characteristics of Ca2SnO4:Eu3+ phosphors were found to depend on the amounts of europium ions. The XRD profiles revealed that the system, (Ca1-xEux)2SnO4, could form stable solid solutions in the composition range of x = 0-7% after being calcined at 1200 °C. The calcined powders emit bright red luminescence centered at 618 nm due to 5D0 → 7F2 electric dipole transition. Both XRD data and the emission ratio of (5D0 → 7F2)/(5D0 → 7F1) reveal that the site symmetry of Eu3+ ions decreases with increasing doping concentration. The maximum PL intensity has been obtained for 7 mol% concentration of Eu3+ in Ca2SnO4.

  11. Structural and luminescent properties of KY(1-x)DyxBO3 phosphors.

    PubMed

    G, Sowjanya; L, Rama Moorthy; Ch, Basavapoornima; C K, Jayasankar

    2017-01-01

    Yttrium borate phosphors (KY(1-x)DyxBO3) doped with Dy(3+) ions were synthesized by the solid-state reaction method. The structural and morphological characteristics were studied by XRD, FTIR and SEM measurements. Luminescent properties of different concentrations of KY(1-x)DyxBO3 phosphors were investigated from the excitation, emission and decay analyses. The emission spectra exhibited characteristic blue (460-500nm) and yellow (555-610nm) bands of Dy(3+) ions which combines to give white light. The evaluated color co-ordinates (x, y) were found to lie within the white light region of CIE chromaticity diagram. All the decay curves of Dy(3+) ions exhibited non-exponential nature and the experimental lifetimes for the (4)F9/2 excited level were found to decrease from 0.87, 0.47, 0.35, 0.26 and 0.13ms with the increase of Dy(3+) ion concentrations from 0.05, 0.1, 0.15, 0.2 and 0.3mol%, respectively. In order to understand the energy transfer mechanism, the decay curves were fitted to Inokutti-Hirayama model and found that the energy transfer is of dipole-dipole type. From the results of these investigations, it is concluded that the KY(1-x)DyxBO3 phosphors are more useful for white light emitting diodes. PMID:27442292

  12. Synthesis, Characterization and Luminescence Properties of Rod-Like LaPO4:Eu3+ Nanostructures.

    PubMed

    Peng, Li; Yun, Liu; Xiaolei, Shi; Yaxin, Guo; Gangqiang, Zhu

    2016-04-01

    Large-scale, rod-like nanostructures of LaPO4:Eu3+ phosphors were synthesized using a simple hydrothermal method. The phase composition, structure and morphology of the final products were characterized by XRD, FE-SEM and TEM. Highly crystalline material was obtained as confirmed by X-ray powder diffraction measurements. The FE-SEM and TEM observations indicate that the obtained LaPO4:Eu3+ nanorods have a diameter of about 10-20 nm, and a length of about 100-600 nm. Meanwhile, the excitation and emission spectra of the products at room temperature were measured using a fluorescence spectrometer. The effects of pH and Eu3+-doping on the morphology and luminescence properties of the as-prepared powders were investigated. The photoluminescence (PL) spectra show that the emission intensity of the LaPO4:Eu3+ phosphors improved with increases in concentrations of Eu3+ from 3 mol% to 14 mol%, and then decreased for higher concentrations. PMID:27451758

  13. Synthesis and properties of new luminescent hole transporting materials containing triphenylamine and carbazole units

    NASA Astrophysics Data System (ADS)

    Gao, Wenzheng; Wang, Shirong; Xiao, Yin; Li, Xianggao

    2012-12-01

    Two new blue luminescent hole transporting materials (HTM) containing triphenylamine, carbazole units and olefinic linkers (TM1 and TM2) were synthesized via Wittig reaction and characterized by 1H NMR, FT-IR, and HRMS. The compounds show good solubility in common organic solvents such as dichloromethane, chloroform, tetrahydrofuran and dimethyl formamide. Their optical, electrochemical and crystalline properties were investigated by using UV-Vis, photoluminescence (PL) spectra, cyclic voltammetry (CV) and differential scanning calorimetry (DSC), respectively. Quantum-chemical calculation was performed to obtain their optimized structures and the electron distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels. The UV-Vis absorption and PL spectra of the two compounds in solid state were found to be similar to that when they were in dilute THF, which suggests that these compounds remain as an amorphous state in solid films. CV measurements show that the two compounds embody suitable HOMO levels (in a range of -5.28 to -5.23 eV) for hole injection, which is consistent with the calculation consequence. Two compounds possess high glass-transition temperature (Tg) at 96.61 and 90.74 °C for TM1 and TM2, respectively, suggesting the two compounds could form stable amorphous glassy states. The experimental results show that the synthesized compounds have great potential for application in organic light-emitting devices (OLEDs).

  14. Synthesis and properties of new luminescent hole transporting materials containing triphenylamine and carbazole units.

    PubMed

    Gao, Wenzheng; Wang, Shirong; Xiao, Yin; Li, Xianggao

    2012-12-01

    Two new blue luminescent hole transporting materials (HTM) containing triphenylamine, carbazole units and olefinic linkers (TM1 and TM2) were synthesized via Wittig reaction and characterized by (1)H NMR, FT-IR, and HRMS. The compounds show good solubility in common organic solvents such as dichloromethane, chloroform, tetrahydrofuran and dimethyl formamide. Their optical, electrochemical and crystalline properties were investigated by using UV-Vis, photoluminescence (PL) spectra, cyclic voltammetry (CV) and differential scanning calorimetry (DSC), respectively. Quantum-chemical calculation was performed to obtain their optimized structures and the electron distribution of the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) energy levels. The UV-Vis absorption and PL spectra of the two compounds in solid state were found to be similar to that when they were in dilute THF, which suggests that these compounds remain as an amorphous state in solid films. CV measurements show that the two compounds embody suitable HOMO levels (in a range of -5.28 to -5.23 eV) for hole injection, which is consistent with the calculation consequence. Two compounds possess high glass-transition temperature (T(g)) at 96.61 and 90.74 °C for TM1 and TM2, respectively, suggesting the two compounds could form stable amorphous glassy states. The experimental results show that the synthesized compounds have great potential for application in organic light-emitting devices (OLEDs). PMID:22958979

  15. Characterization and luminescence properties of Sr3Gd): Sm3+ orange-red phosphor

    NASA Astrophysics Data System (ADS)

    Yang, Zaifa; Xu, Denghui; Sun, Jiayue; Sun, Yumei; Du, Haiyan

    2015-10-01

    Reddish-orange emitting phosphors, Sr3Gd): Sm3+, were successfully synthesized by a conventional solid-state reaction. The crystal structure of the phosphors was characterized by x-ray diffraction. The excitation spectra and emission spectra were utilized to characterize the luminescence properties of the as-prepared phosphors. The results show that the phosphor consisted of some sharp emission peaks of Sm3+ ions centered at 564, 600, 647, and 707 nm, respectively. The critical distance of Sr3Gd0.93): 0.07Sm3+ was calculated to be 19.18 Å and the lifetime value of the sample was 1.63 ms. The band gap of Sr3Gd) was estimated to be about 2.74 eV from the diffuse reflection spectrum. The optimum doping concentration is 7 mol. % and the quenching occurs via dipole-dipole interaction according to Dexter's theory. The Commission Internationale de L'Eclairage value of Sr3Gd): Sm3+ phosphors presented that it has high color purity. These results indicated that the Sr3Gd): Sm3+ may be a promising reddish-orange emitting phosphor for cost-effective near ultraviolet white light-emitting diodes.

  16. Synthesis and Luminescence Properties of Core/Shell ZnS:Mn/ZnO Nanoparticles

    NASA Astrophysics Data System (ADS)

    Jiang, Daixun; Cao, Lixin; Liu, Wei; Su, Ge; Qu, Hua; Sun, Yuanguang; Dong, Bohua

    2009-01-01

    In this paper the influence of ZnO shell thickness on the luminescence properties of Mn-doped ZnS nanoparticles is studied. Transmission electron microscopy (TEM) images showed that the average diameter of ZnS:Mn nanoparticles is around 14 nm. The formation of ZnO shells on the surface of ZnS:Mn nanoparticles was confirmed by X-ray diffraction (XRD) patterns, high-resolution TEM (HRTEM) images, and X-ray photoelectron spectroscopy (XPS) measurements. A strong increase followed by a gradual decline was observed in the room temperature photoluminescence (PL) spectra with the thickening of the ZnO shell. The photoluminescence excitation (PLE) spectra exhibited a blue shift in ZnO-coated ZnS:Mn nanoparticles compared with the uncoated ones. It is shown that the PL enhancement and the blue shift of optimum excitation wavelength are led by the ZnO-induced surface passivation and compressive stress on the ZnS:Mn cores.

  17. Molten salt synthesis and luminescent properties of YVO4:Ln (Ln = Eu3+, Dy3+) nanophosphors.

    PubMed

    Liu, Chenglu; Wang, Fang; Jia, Peiyun; Lin, Jun; Zhou, Zhiqiang

    2012-01-01

    Eu3+ and Dy(3+)-doped YVO4 nanocrystallites were successfully prepared at 400 degrees C in equal moles of NaNO3 and KNO3 molten salts. X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, transmission electronic microscopy (TEM), photoluminescence (PL) spectrum and lifetime were used to characterize the nanocrystallites. XRD results demonstrate that NaOH concentration and annealing temperature play important roles in phase purity and crystallinity of the nanocrystallites, the optimum NaOH concentration and annealing temperature being 6:40 and 400 degrees C respectively. TEM micrographs show the nanocrystallites are well crystallized with a cubic morphology in an average grain size of about 18 nm. Upon excitation of the vanadate group at 314 nm, YVO4:Eu3+ and YVO4:Dy3+ nanocrystallites exhibit the characteristic emission of Eu3+ and Dy3+, which indicates that there is an energy transfer from the vanadate group to the rare earth ions. Moreover, the structure and luminescent properties of the nanocrystallites were compared with their bulk counterparts with same composition in detail. PMID:22523959

  18. Luminescence properties of individual empty and water-filled single-walled carbon nanotubes.

    PubMed

    Cambré, Sofie; Santos, Silvia M; Wenseleers, Wim; Nugraha, Ahmad R T; Saito, Riichiro; Cognet, Laurent; Lounis, Brahim

    2012-03-27

    The influence of water filling on the photoluminescence (PL) properties of SWCNTs is studied by ensemble and single-molecule PL spectroscopy. Red-shifted PL and PL excitation spectra are observed upon water filling for 16 chiralities and can be used to unambiguously distinguish empty SWCNTs from filled ones. The effect of water filling on the optical transitions is well-reproduced by a continuum dielectric constant model previously developed to describe the influence of the nanotube outer environment. Empty nanotubes display narrower luminescence lines and lower inhomogeneous broadening, signatures of reduced extrinsic perturbations. The radial breathing mode phonon sideband is clearly observed in the PL spectrum of small diameter empty tubes, and a strong exciton-phonon coupling is measured for this vibration. Biexponential PL decays are observed for empty and water-filled tubes, and only the short-living component is influenced by the water filling. This may be attributed to a shortening of the radiative lifetime of the bright state by the inner dielectric environment. PMID:22314108

  19. New ages for Middle and Later Stone Age deposits at Mumba rockshelter, Tanzania: optically stimulated luminescence dating of quartz and feldspar grains.

    PubMed

    Gliganic, Luke A; Jacobs, Zenobia; Roberts, Richard G; Domínguez-Rodrigo, Manuel; Mabulla, Audax Z P

    2012-04-01

    The archaeological deposits at Mumba rockshelter, northern Tanzania, have been excavated for more than 70 years, starting with Margit and Ludwig Köhl-Larsen in the 1930s. The assemblages of Middle Stone Age (MSA) and Later Stone Age (LSA) artefacts collected from this site constitute the type sequences for these cultural phases in East Africa. Despite its archaeological importance, however, the chronology of the site is poorly constrained, despite the application since the 1980s of several dating methods (radiocarbon, uranium-series and amino acid racemisation) to a variety of materials recovered from the deposits. Here, we review these previous chronologies for Mumba and report new ages obtained from optically stimulated luminescence (OSL) and infrared stimulated luminescence (IRSL) measurements on single grains of quartz and multi-grain aliquots of potassium (K) feldspar from the MSA and LSA deposits. Measurements of single grains of quartz allowed the rejection of unrepresentative grains and the application of appropriate statistical models to obtain the most reliable age estimates, while measurements of K-feldspars allowed the chronology to be extended to older deposits. The seven quartz ages and four K-feldspar ages provide improved temporal constraints on the archaeological sequence at Mumba. The deposits associated with the latest Kisele Industry (Bed VI-A) and the earliest Mumba Industry (Bed V) are dated to 63.4 ± 5.7 and 56.9 ± 4.8 ka (thousands of years ago), respectively, thus constraining the time of transition between these two archaeological phases to ~60 ka. An age of 49.1 ± 4.3 ka has been obtained for the latest deposits associated with the Mumba Industry, which show no evidence for post-depositional mixing and contain ostrich eggshell (OES) beads and abundant microlithics. The Nasera Industry deposits (Bed III) contain large quantities of OES beads and date to 36.8 ± 3.4 ka. We compare the luminescence ages with the previous chronologies for

  20. Near Infrared Luminescence Properties of Mn(5+): Ca5(PO4)3F

    NASA Technical Reports Server (NTRS)

    Davis, Valetta R.; Hoemmerich, Uwe; Loutts, George B.

    1997-01-01

    We report a spectroscopic investigation of Mn(5+) doped Ca5(PO4)(sub 3)F or FAP. Mn(5+) doped crystals have recently attracted world wide attention for potential solid-state laser applications. Following optical excitation of Mn: FAP with the 600 nm output of a Nd: YAG OPO laser system, we observed a strong near infrared luminescence centered at around 1150 nm. The room temperature luminescence decay time was measured to be approximately 635 microseconds. We attribute the infrared luminescence to the(1)E yields (3)A2 transition of tetrahedrally coordinated Mn5+ ions located in a strong crystal field environment. Absorption, luminescence and lifetime data of Mn: FAP will be presented and discussed.

  1. One-step synthesis and luminescence properties of tetragonal double tungstates nanocrystals.

    PubMed

    Wang, Z J; Zhang, Y L; Zhong, J P; Yao, H H; Wang, J; Wu, M M; Meijerink, A

    2016-08-25

    A versatile one-step thermolysis protocol is demonstrated to produce a uniform dispersion of tetragonal double tungstates NaRE(WO4)2 (RE = rare earth) nanocrystals (NCs). Oriented attachment in the [001] direction occurred. Doping with luminescent RE(3+) ions resulted in highly luminescent NCs showing characteristic line emission of the dopant as well as a blue emission assigned to surface adsorbed organic species. PMID:27524472

  2. Synthesis, crystal structure and luminescence properties of lanthanide coordination polymers with a new semirigid bridging thenylsalicylamide ligand

    SciTech Connect

    Song, Xue-Qin Wang, Li; Zhao, Meng-Meng; Wang, Xiao-Run; Peng, Yun-Qiao; Cheng, Guo-Quan

    2013-09-15

    Two new lanthanide coordination polymers based on a semirigid bridging thenylsalicylamide ligand ([Ln{sub 2}L{sub 3}(NO{sub 3}){sub 6}]·(C{sub 4}H{sub 8}O{sub 2}){sub 2}){sub ∞} were obtained and characterized by elemental analysis, X-ray diffraction, IR and TGA measurements. The two compounds are isostructure and possess one dimensional trapezoid ladder-like chain built up from the connection of isolated LnO{sub 3}(NO{sub 3}){sub 3} polyhedra (distorted monocapped antisquare prism) through the ligand. The photoluminescence analysis suggest that there is an efficient ligand-to-Ln(III) energy transfer in Tb(III) complex and the ligand is an efficient “antenna” for Tb(III). From a more general perspective, the results demonstrated herein provide the possibility of controlling the formation of the desired lanthanide coordination structure to enrich the crystal engineering strategy and enlarge the arsenal for developing excellent luminescent lanthanide coordination polymers. - Graphical abstract: We present herein one dimensional lanthanide coordination polymers of a new semirigid exo-bidentate ligand which not only display interesting structures but also possess strong luminescence properties. Display Omitted - Highlights: • We present lanthanide coordination polymers of a new semirigid exo-bidentate ligand. • The lanthanide coordination polymers exhibit interesting structures. • The luminescent properties of Tb(III) complexes are discussed in detail.

  3. Hydrothermal Synthesis and Luminescent Properties of Eu3+ Doped Sr3Al2O6 Phosphor for White LED.

    PubMed

    Li, Xu; Pan, Heng; Tang, Aiwei; Zhang, Jinping; Guan, Li; Su, Hongxin; Dong, Guoyi; Yang, Zhiping; Wang, Huike; Teng, Feng

    2016-04-01

    Eu3+ ions doped Sr3Al2O6 phosphors were successfully synthesized via a hydrothermal method. The precursor was prepared by low temperature hydrothermal method using ammonia as both alkaline source and precipitator. Then the final product was obtained by high temperature sintering. In addition, the structures, morphologies, and luminescent properties of as-prepared products were thoroughly characterized by X-ray powder diffraction (XRD), Scanning electron microscopy (SEM), Fluorescence spectroscopy (PL). XRD shown a single phase Sr3Al2O6 prepared by a facile hydrothermal method at 250 °C for 10 h. In the PL spectra of as-prepared samples, the optimal value of Eu3+ concentration is 2 mol%. From the fluorescent spectra, the emission peaks of Sr3Al2O6: Eul+ phosphors are centered at around 591 nm, and the excitation peaks are centered at around 233 nm, 323 nm, 394 nm, and 468 nm, respectively, which were assigned to the characteristic transition of Eu3+ ions. The influence of ammonia, and the synthesis temperature on the luminescent properties of Sr3Al206: Eu3+ phosphors were studied in detail. The alkaline earth aluminates luminescent materials activated by rare earth ions have good prospects in the field of new-generation light sources. PMID:27451652

  4. Preparation and luminescence properties of phosphors of rare earth complexes based on polyoxotungstates

    SciTech Connect

    Wen, He-Rui; Lu, Xiao-Neng; Liao, Jin-Sheng; Zhang, Cai-Wei; You, Hang-Ying; Liu, Cai-Ming

    2015-08-15

    Highlights: • Three new phosphors of rare earth complexes based on polyoxotungstates were synthesized. • [Eu(PW{sub 11}O{sub 39}){sub 2}]{sup 11−} (1) emits red light which used as potential red light materials. • [Sm(PW{sub 11}O{sub 39}){sub 2}] {sup 11−} (2) emits strong orange-red light at 598.7 nm. • [Dy(PW{sub 11}O{sub 39}){sub 2}] {sup 11−} (3) emits white light which used as potential white light materials. - Abstract: Three new phosphors of rare earth complexes based on polyoxotungstates, K{sub 3}Cs{sub 8}[Eu(PW{sub 11}O{sub 39}){sub 2}]·11H{sub 2}O (1), K{sub 3}Cs{sub 8}[Sm(PW{sub 11}O{sub 39}){sub 2}]·10H{sub 2}O (2), and K{sub 5}Cs{sub 6}[Dy(PW{sub 11}O{sub 39}){sub 2}]·15H{sub 2}O (3) have been prepared and characterized. The crystallographic analyses reveal that these compounds consist of two monovacant keggin anions [PW{sub 11}O{sub 39}]{sup 7−} connected by a rare earth ion in a sandwich structure. The investigations of photoluminescence properties show that phosphor 1 emits strong red light at 614 and 702 nm, 2 emits strong orange-red light at 598.7 nm, and 3 exists two strong emissions at 479 nm (blue) and 574 nm (orange). The luminescence properties suggest that the 1 can be applied as the potential red-emitting crystal phosphor, and the 3 may be regarded as a potential white light material for LEDs.

  5. Self-Assembled NaTb1-xEux(MoO4)2: Synthesis and Luminescence Properties.

    PubMed

    Liu, Xiaoqing; Qu, Lingnan; Wang, Shuo; Li, Lv; Su, Yiguo; Wang, Xiaojing

    2016-04-01

    Novel 3D Eu3+ doped NaTb(MoO4)2 composites were successfully self-assembled by a facile hydrothermal treatment. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM) and photoluminescence (PL) spectra were used to characterize the structures, morphologies and the luminescent properties of as-prepared products. Emission and excitation spectra showed that the phosphor exhibits a dominant red emission at 615 nm with excitation wavelength of 465 nm at room temperature. The emission intensity increased with the increase of Eu3+ concentrations for the investigated range of 2-10 mol% Eu3+ doping in NaTb(MoO4)2. The doping of Eu3+ results in a distorted Eu-0. cluster and enhanced luminescence intensity. PMID:27451692

  6. Structural and up-conversion luminescence properties in Tm3+/Yb3+-codoped heavy metal oxide-halide glasses.

    PubMed

    Sun, Hongtao; Duan, Zhongchao; Zhou, Gang; Yu, Chunlei; Liao, Meisong; Hu, Lili; Zhang, Junjie; Jiang, Zhonghong

    2006-01-01

    Tm3+/Yb3+-codoped heavy metal oxide-halide glasses have been synthesized by conventional melting and quenching method. Structural properties were obtained based on the Raman spectra, indicating that halide ion has an important influence on the phonon density and maximum phonon energy of host glasses. Intense blue and weak red emissions centered at 477 and 650 nm, corresponding to the transitions 1G4-->3H6 and 1G4-->3H4, respectively, were observed at room temperature. The possible up-conversion mechanisms are discussed and estimated. With increasing halide content, the up-conversion luminescence intensity and blue luminescence lifetimes of Tm3+ ion increase notably. Our results show that with the substitution of halide ion for oxygen ion, the decrease of phonon density and maximum phonon energy of host glasses both contribute to the enhanced up-conversion emissions. PMID:15950531

  7. [Modification and luminescence properties of transparent Lu2SiO5 : Ce3+ thin-film phosphors].

    PubMed

    Fan, Yang-Yang; Liu, Xiao-Lin; Gu, Mu; Ni, Chen; Huang, Shi-Ming; Liu, Bo

    2011-02-01

    To achieve high-spatial-resolution for X-ray imaging and flat panel display, transparent thin-film phosphors have been attracted much attention in recent years. In comparison with conventional powder phosphors, the transparent thin-film phosphors have some outstanding advantages such as high contrast and resolution, superior thermal conductivity and better adhesion. Cerium-doped lutetium oxyorthosilicate Lu2 SiO5 (LSO) is one promising candidate due to its high density (7.4 g x cm(-3)), high light yield (27 300 photons x MeV(-1)), short decay time (40 ns), and excellent chemical stability. The sol-gel method is one of the most important techniques for deposition of functional thin films, because it possesses a number of advantages over conventional film formation techniques, such as low processing temperature, easy coating of large surfaces, homogenous multicomponent films, and cheap equipments. In X-ray imaging application, the thickness of the thin-film phosphor is the most important factor, which can increase X-ray absorption of the film and then strengthen its luminescence intensity. In the present work, transparent LSO : Ce film was successfully prepared using sol-gel method and spin-coating technique by using inorganic salts as raw materials, 2-methoxyethanol as solvent, and poly (ethylene glycol) (PEG) as modifier without inert atmosphere. The effect of PEG on the luminescence properties of the film was investigated in detail. The results indicated that PEG200 played an important role in the formation of LSO : Ce film, improving its quality and luminescent intensity. The film thickness of 0.9 microm was achieved after 5 times of coating. The luminescence properties of the film were studied. Their performances were good, which implied that the film would have promising applications in high-spatial-resolution X-ray imaging and flat panel display devices. PMID:21510377

  8. Rare earth doped LiYbF{sub 4} phosphors with controlled morphologies: Hydrothermal synthesis and luminescent properties

    SciTech Connect

    Huang, Wenjuan; Lu, Chunhua; Jiang, Chenfei; Jin, Junyang; Ding, Mingye; Ni, Yaru; Xu, Zhongzi

    2012-06-15

    Highlights: ► LiYbF{sub 4} microparticles as an excellent upconverting materials. ► High temperature and long time can favor high crystalline LiYbF{sub 4} microparticles. ► The shape of LiYbF{sub 4} microparticles can be tuned by the molar ratio of EDTA to Yb{sup 3+}. ► Bright green emission can be obtained by changing the doping concentration of Er{sup 3+}. -- Abstract: High quality monodisperse LiYbF{sub 4} microparticles with shape of octahedron had been prepared via a facile hydrothermal route. The crystalline phase, size, morphology and luminescence properties were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), photoluminescence (PL) spectra and Commission Internationale de L’Eclairage (CIE 1931) chromaticity coordinates, respectively. The influences of reaction temperature, reaction time and the molar ratio of EDTA to Yb{sup 3+} on the crystal phases and shapes of as-prepared products had been investigated in detail. The upconversion (UC) luminescence properties of LiYb{sub 1−x}F{sub 4}:xEr{sup 3+} (x =0.1, 0.2, 0.5, 1, 2, 5 and 10 mol%) particles with octahedral microstructures were studied under 976 nm excitation. The results showed that the luminescence colors of the corresponding products could be tuned to bright green by changing the doping concentration of Er{sup 3+} ion. The luminescence mechanisms for the doped Er{sup 3+} ion were thoroughly analyzed, showing great potential in applications such as biolabels, displays and other optical technologies.

  9. Spectral and Luminescence Properties of Sols and Coatings Containing CdS/ZnS QDs and Polyvinylpyrrolidone

    NASA Astrophysics Data System (ADS)

    Evstrop'ev, K. S.; Gatchin, Yu. A.; Evstrop'ev, S. K.; Dukel'skii, K. V.; Kislyakov, I. M.; Pegasova, N. A.; Bagrov, I. V.

    2016-03-01

    Spectral and luminescence properties of sols and composition coatings containing cadmium and zinc sulfides and high-molecular polyvinylpyrrolidone have been studied. It is shown that the absorption spectra of colloidal solutions in the UV spectral range are determined by the quantum-confinement effect and exhibit a dependence of the absorption edge on the size of cadmium sulfide nanocrystals. The size of forming particles of metal sulfides has been found to decrease with an increase in the relative content of polyvinylpyrrolidone. It is shown that the order of mixing of the initial components when synthesizing sols also determines the difference in the size of forming particles and their spectral properties.

  10. Multichannel dosemeter and Al2O3:C optically stimulated luminescence fibre sensors for use in radiation therapy: evaluation with electron beams.

    PubMed

    Magne, S; Auger, L; Bordy, J M; de Carlan, L; Isambert, A; Bridier, A; Ferdinand, P; Barthe, J

    2008-01-01

    This article proposes an innovative multichannel optically stimulated luminescence (OSL) dosemeter for on-line in vivo dose verification in radiation therapy. OSL fibre sensors incorporating small Al(2)O(3):C fibre crystals (TLD(500)) have been tested with an X-ray generator. A reproducible readout procedure should reduce the fading-induced uncertainty ( approximately - 1% per decade). OSL readouts are temperature-dependent [ approximately 0.3% K(-1) when OSL stimulation is performed at the same temperature as irradiation; approximately 0.16% K(-1) after thermalisation (20 degrees C)]. Sensor calibration and depth-dose measurements with electron beams have been performed with a Saturne 43 linear accelerator in reference conditions at CEA-LNHB (ionising radiation reference laboratory in France). Predosed OSL sensors show a good repeatability in multichannel operation and independence versus electron energy in the range (9, 18 MeV). The difference between absorbed doses measured by OSL and an ionisation chamber were within +/-0.9% (for a dose of about 1 Gy) despite a sublinear calibration curve. PMID:18757901

  11. Investigation on three new metal carboxydiphosphonates: Syntheses, structures, magnetic and luminescent properties

    SciTech Connect

    Tang Sifu; Pan Xiaobo; Lv Xiaoxia; Zhao Xuebo

    2013-01-15

    A new multifunctionalized phosphoric acid, (2-(diphosphonomethylamino)nicotinic acid, Py(COOH)(NHCH--(PO{sub 3}H{sub 2}){sub 2}), H{sub 5}L{sup 1}), has been employed as ligand for the construction of new metal phosphonates. By reacting it with different metal chlorides under hydrothermal condition, three new transition metal phosphonates, namely, [Co{sub 2}(HL{sup 1})(H{sub 2}O){sub 5}][H{sub 2}O]{sub 3} (1), Zn(H{sub 3}L{sup 1}) (2) and [Cd(H{sub 3}L{sup 1})(H{sub 2}O){sub 2}][H{sub 2}O] (3) were successfully obtained. The single-crystal structure measurements indicated that the coordination mode of ligand H{sub 5}L{sup 1} is metal-dependant and results in different structures. For compound 1, it features 2D layered structure. Whereas compounds 2 and 3 have 1D chain structures. Under the excitation of 250 nm light, both compounds 2 and 3 show intraligand and ligand to metal charge transfer (LMCT) emission bands at about 415 and 420 nm, respectively. Magnetic study shows that compound 1 displays antiferromagnetic behavior. - Graphical abstract: Three new metal phosphonates were synthesized from a multifunctionalized phosphonate ligand and different metal chlorides. Their structures, thermal stabilities, luminescent and magnetic properties were characterized. Highlights: Black-Right-Pointing-Pointer Three new metal phosphonates were synthesized under hydrothermal conditions. Black-Right-Pointing-Pointer Compound 1 exhibits 2D layered structure. Black-Right-Pointing-Pointer Compounds 2 and 3 have 1D infinite chain structures. Black-Right-Pointing-Pointer Compound 1 displays antiferromagnetic behavior. Black-Right-Pointing-Pointer Compounds 2 and 3 show intraligand and ligand to metal charge transfer emission bands.

  12. Luminescence properties of dysprosium doped di-calcium di-aluminium silicate phosphors

    NASA Astrophysics Data System (ADS)

    Tiwari, Geetanjali; Brahme, Nameeta; Sharma, Ravi; Bisen, D. P.; Sao, Sanjay K.; Tigga, Shalinta

    2016-08-01

    A Dysprosium doped di-calcium di-aluminium silicate phosphor emitting long-lasting white light was prepared and investigated. Phosphors were synthesized by combustion-assisted method. The effect of doping concentration on the crystal structure and luminescence properties of Ca2Al2SiO7:Dy3+ phosphors were investigated. The phase structure, surface morphology, particle size, elemental analysis was analyzed by using X-ray diffraction (XRD), transmission electron microscope (TEM), Scanning electron microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDX) techniques. X-ray diffraction (XRD) profiles showed that all peaks could be attributed to the tetragonal Ca2Al2SiO7 phase when the sample was annealed at 1100 °C. The increase in TL intensity indicates that the concentration of traps increases with UV irradiation. Under the UV-excitation, the Thermoluminescence (TL) emission spectra of Ca2Al2SiO7:Dy3+ phosphor shows the characteristic emission of Dy3+ peaking at 484 nm (blue), 583 nm (yellow) and 680 nm (red), originating from the transitions of 4F9/2 → 6H15/2, 4F9/2 → 6H13/2 and 4F9/2 → 6H11/2. Photoluminescence (PL) decay has also reported and it indicates that Ca2Al2SiO7:Dy3+ phosphor contains fast decay and slow decay process. The peak of Mechanoluminescence (ML) intensity increases linearly with increasing impact velocity of the moving piston. The possible mechanism of Thermoluminescence (TL), Photoluminescence (PL) and Mechanoluminescence (ML) of this white light emitting long lasting phosphor is also investigated.

  13. Three-Dimensional Assembly of Yttrium Oxide Nanosheets into Luminescent Aerogel Monoliths with Outstanding Adsorption Properties.

    PubMed

    Cheng, Wei; Rechberger, Felix; Niederberger, Markus

    2016-02-23

    The preparation of macroscopic materials from two-dimensional nanostructures represents a great challenge. Restacking and random aggregation to dense structures during processing prevents the preservation of the two-dimensional morphology of the nanobuilding blocks in the final body. Here we present a facile solution route to ultrathin, crystalline Y2O3 nanosheets, which can be assembled into a 3D network by a simple centrifugation-induced gelation method. The wet gels are converted into aerogel monoliths of macroscopic dimensions via supercritical drying. The as-prepared, fully crystalline Y2O3 aerogels show high surface areas of up to 445 m(2)/g and a very low density of 0.15 g/cm(3), which is only 3% of the bulk density of Y2O3. By doping and co-doping the Y2O3 nanosheets with Eu(3+) and Tb(3+), we successfully fabricated luminescent aerogel monoliths with tunable color emissions from red to green under UV excitation. Moreover, the as-prepared gels and aerogels exhibit excellent adsorption capacities for organic dyes in water without losing their structural integrity. For methyl blue we measured an unmatched adsorption capacity of 8080 mg/g. Finally, the deposition of gold nanoparticles on the nanosheets gave access to Y2O3-Au nanocomposite aerogels, proving that this approach may be used for the synthesis of catalytically active materials. The broad range of properties including low density, high porosity, and large surface area in combination with tunable photoluminescence makes these Y2O3 aerogels a truly multifunctional material with potential applications in optoelectronics, wastewater treatment, and catalysis. PMID:26756944

  14. Structure–mechanical property correlations in mechanochromic luminescent crystals of boron difluoride dibenzoylmethane derivatives

    PubMed Central

    Krishna, Gamidi Rama; Devarapalli, Ramesh; Prusty, Rajesh; Liu, Tiandong; Fraser, Cassandra L.; Ramamurty, Upadrasta; Reddy, Chilla Malla

    2015-01-01

    The structure and mechanical properties of crystalline materials of three boron difluoride dibenzoylmethane (BF2dbm) derivatives were investigated to examine the correlation, if any, among mechanochromic luminescence (ML) behaviour, solid-state structure, and the mechanical behaviour of single crystals. Qualitative mechanical deformation tests show that the crystals of BF2dbm(tBu)2 can be bent permanently, whereas those of BF2dbm(OMe)2 exhibit an inhomogeneous shearing mode of deformation, and finally BF2dbmOMe crystals are brittle. Quantitative mechanical analysis by nano­indentation on the major facets of the crystals shows that BF2dbm(tBu)2 is soft and compliant with low values of elastic modulus, E, and hardness, H, confirming its superior suceptibility for plastic deformation, which is attributed to the presence of a multitude of slip systems in the crystal structure. In contrast, both BF2dbm(OMe)2 and BF2dbmOMe are considerably stiffer and harder with comparable E and H, which are rationalized through analysis of the structural attributes such as the intermolecular interactions, slip systems and their relative orientation with respect to the indentation direction. As expected from the qualitative mechanical behaviour, prominent ML was observed in BF2dbm(tBu)2, whereas BF2dbm(OMe)2 exhibits only a moderate ML and BF2dbmOMe shows no detectable ML, all examined under identical conditions. These results confirm that the extent of ML in crystalline organic solid-state fluorophore materials can be correlated positively with the extent of plasticity (low recovery). In turn, they offer opportunities to design new and improved efficient ML materials using crystal engineering principles. PMID:26594368

  15. Luminescence properties of Eu-complex formations into ordered mesoporous silica particles obtained by the spray pyrolysis process

    NASA Astrophysics Data System (ADS)

    Rocha, Lucas A.; Freiria, Janaina do C.; Caiut, José Maurício A.; Ribeiro, Sidney J. L.; Messaddeq, Younes; Verelst, Marc; Dexpert-Ghys, Jeannette

    2015-08-01

    Ordered mesoporous, highly luminescent SiO2 particles have been synthesized by spray pyrolysis from solutions containing tetraethylorthosilicate (TEOS), Eu(NO3)3.6H2O, and cetyltrimethylammonium bromide (CTAB) as structure-directing agents. The 1,10-phenantroline (Phen) molecules were coordinated in a post-synthesis step by a simple wet impregnation method. In addition, other matrices were also prepared by the encapsulation of europium complex Eu(fod)3 (where fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) into mesoporous silica, and then the Phen molecules were encapsulated by different impregnation steps, after which the luminescence properties were investigated. The obtained materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Powders with polydisperse spherical grains were obtained, displaying an ordered hexagonal array of mesochannels. Luminescence results revealed that Phen molecules had been successfully coordinated as an additional ligand in the Eu(fod)3 complex into the channels of the mesoporous particles without disrupting the structure.

  16. Controllable synthesis and luminescence properties of TiO2:Eu3+ nanorods, nanoparticles and submicrospheres by hydrothermal method

    NASA Astrophysics Data System (ADS)

    Qi, Xiaofei; Song, Yanhua; Sheng, Ye; Zhang, Hongguang; Zhao, Huan; Shi, Zhan; Zou, Haifeng

    2014-12-01

    Eu3+-doped TiO2 nanocrystals with three kinds of morphologies (nanorods, nanoparticles, and submicrospheres) have been successfully fabricated in cetyltrimethylammonium bromide (CTAB)/water/cyclohexane/n-pentanol reverse micelle by hydrothermal method for the first time and their photoluminescence (PL) properties have also been studied. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), FT-IR, and PL spectra were used to characterize the samples. The acidic and alkaline conditions of the microemulsion play an important role in determining the geometric morphologies of the final products. TiO2:Eu3+ with three different morphologies all exist only in anatase phase and show high luminescence intensity without further calcinations, which show its advantages of energy saving. The shape of emission spectra was independent of the morphologies of the products but the luminescence intensity of the TiO2:Eu3+ materials is strongly dependent on their morphology. The results show that TiO2:Eu3+ nanorods possess the strongest luminescence intensity among the three nanostructured samples.

  17. Luminescence properties of Eu-complex formations into ordered mesoporous silica particles obtained by the spray pyrolysis process.

    PubMed

    Rocha, Lucas A; Freiria, Janaina do C; Caiut, José Maurício A; Ribeiro, Sidney J L; Messaddeq, Younes; Verelst, Marc; Dexpert-Ghys, Jeannette

    2015-08-21

    Ordered mesoporous, highly luminescent SiO2 particles have been synthesized by spray pyrolysis from solutions containing tetraethylorthosilicate (TEOS), Eu(NO3)3.6H2O, and cetyltrimethylammonium bromide (CTAB) as structure-directing agents. The 1,10-phenantroline (Phen) molecules were coordinated in a post-synthesis step by a simple wet impregnation method. In addition, other matrices were also prepared by the encapsulation of europium complex Eu(fod)3 (where fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octanedionato) into mesoporous silica, and then the Phen molecules were encapsulated by different impregnation steps, after which the luminescence properties were investigated. The obtained materials were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), powder x-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy. Powders with polydisperse spherical grains were obtained, displaying an ordered hexagonal array of mesochannels. Luminescence results revealed that Phen molecules had been successfully coordinated as an additional ligand in the Eu(fod)3 complex into the channels of the mesoporous particles without disrupting the structure. PMID:26222799

  18. Anodic luminescence, structural, photoluminescent, and photocatalytic properties of anodic oxide films grown on niobium in phosphoric acid

    NASA Astrophysics Data System (ADS)

    Stojadinović, Stevan; Tadić, Nenad; Radić, Nenad; Stefanov, Plamen; Grbić, Boško; Vasilić, Rastko

    2015-11-01

    This article reports on properties of oxide films obtained by anodization of niobium in phosphoric acid before and after the dielectric breakdown. Weak anodic luminescence of barrier oxide films formed during the anodization of niobium is correlated to the existence of morphological defects in the oxide layer. Small sized sparks generated by dielectric breakdown of formed oxide film cause rapid increase of luminescence intensity. The luminescence spectrum of obtained films on niobium under spark discharging is composed of continuum radiation and spectral lines caused by electronic spark discharging transitions in oxygen and hydrogen atoms. Oxide films formed before the breakdown are amorphous, while after the breakdown oxide films are partly crystalline and mainly composed of Nb2O5 hexagonal phase. The photocatalytic activity of obtained oxide films after the breakdown was investigated by monitoring the degradation of methyl orange. Increase of the photocatalytic activity with time is related to an increase of oxygen vacancy defects in oxide films formed during the process. Also, higher concentration of oxygen vacancy defects in oxide films results in higher photoluminescence intensity.

  19. Sol-gel synthesis and luminescent properties of red-emitting Y(P,V)O4:Eu(3+) phosphors.

    PubMed

    Zhang, Xinguo; Zhou, Fangxiang; He, Pei; Zhang, Min; Gong, Menglian

    2016-02-01

    Eu(3+)-activated Y(P,V)O4 phosphors were prepared by the EDTA sol-gel method, and the corresponding morphologies and luminescent properties were investigated. The sample particles were relatively spheroid with size of 2-3 µm and had a smooth surface. The excitation spectra for Y(P,V)O4:Eu(3+) consisted of three strong excitation bands in the 200-350 nm range, which were attributed to a Eu(3+)- O(2-) charge-transfer band and (1)A1-(1) T1/(1) T2 transitions in VO4(3-). The as-synthesized phosphors exhibited a highly efficient red luminescence at 613 nm due to the Eu(3+5) D0-(7) F2 electric dipole transition. With the increase in the V(5+)/P(5+) ratio, the luminescence intensity of the red phosphor under UV excitation was greatly improved due to enhanced VO4(3-) → Eu(3+) energy transfer. PMID:26097078

  20. Exceptional Oxygen Sensing Properties of New Blue Light-Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

    PubMed Central

    Borisov, Sergey M.; Fischer, Roland; Saf, Robert; Klimant, Ingo

    2016-01-01

    New europium(III) and gadolinium(III) complexes bearing 8-hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state-of-the-art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow-band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g. in multi-analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state-of-the-art oxygen indicators particularly for such applications as e.g. food packaging. PMID:27158252

  1. Investigation on upconversion luminescence properties of Gd2O3: Ho3+/Yb3+/Tm3+ nanotubes

    NASA Astrophysics Data System (ADS)

    Ye, Fei; Fang, Yu; Liu, Xiao-bo; Xu, Fang; Song, Ying-lin

    2013-09-01

    Lanthanide doped oxides nano materials have novel optical, physical and structural properties. Cubic Ho3+-Yb3+-Tm3+ co-doped Gd2O3 nanotubes are synthetize by a simple wet-chemical route at low temperature and ambient pressure followed by subsequent annealing heat treatment in muffle furnace. Nanotubes are formed by adjusting the pH value of reacting solution. The introduction of Yb3+ leads to strong visible upconversion luminescence and change the intensity ratio of the green, blue and red luminescence. In trichromatic laser display, research of how to enhance blue light is in the bottleneck period. In the experiment, the blue emission has been successfully improved. In certain doping ratio, distinct enhancement of blue emission and obvious degradation of green light have been observed, which is discussed in detail. X-Ray powder diffraction (XRD), scanning electron microscope (SEM) and upconversion (UC) emission spectra are used to characterize the sample. Strong and adjusted upconversion luminescence determine that the nano material is a potential candidate for applications of biological probe, color displays, lighting and photonics.

  2. Effect of ultraviolet irradiation on luminescence properties of undoped ZnS and ZnS:Ag nanoparticles

    SciTech Connect

    Qu Hua; Cao Lixin; Su Ge; Liu Wei; Sun Yuanguang; Dong Bohua

    2009-11-01

    Undoped ZnS and ZnS:Ag nanoparticles have been prepared through hydrothemal synthesis. The changes of luminescence properties induced by ultraviolet irradiation have been investigated. For both samples, the initial slight increase in luminescence is ascribed to the fast electron filling, while the succedent decrease is supposed to be caused by nonradiative pathways originating from some unknown photochemical products. The more remarkable decrease in ZnS:Ag is put down to the segregation of Ag on the surfaces of ZnS:Ag nanoparticles. Multipeaks Gaussian fitting is applied to the emission spectra. The fitting peaks around 490 nm in both samples are related with the surface states emission and the fitting peaks around 456 nm in ZnS nanoparticles and 443 nm in ZnS:Ag nanoparticles are attributed to the type of donor-acceptor pair luminescence, which corresponds to the transition between different donor levels and acceptor levels in different samples. A model of stretched exponential function is used to fit the fluorescence decay spectra. Result shows that the introduction of Ag{sup +} ions causes a spectacular lifetime shortening of ZnS. Experiment result also verifies the model as that the lifetimes of both samples are notably shortened after irradiation for 2 h.

  3. Polarization properties of long-lived stimulated photon echo

    NASA Astrophysics Data System (ADS)

    Reshetov, V. A.; Popov, E. N.

    2015-01-01

    The polarization properties of the long-lived stimulated photon echo formed on the transition ja → jb with the atomic levels degenerate in the projections of the angular momenta are studied theoretically. The two particular transitions ja = 1 → jb = 0 and ja = 1 → jb = 1 with degenerate ground state ja = 1 are discussed. For the transitions ja = 1 → jb = 1 the polarizations and areas of the first (‘write’) and the third (‘read’) excitation pulses are found when the echo polarization faithfully reproduces the arbitrary polarization of the weak (single-photon) second (‘information’) pulse, so that this echo scheme may implement the quantum memory for a single-photon polarization qubit, while for the transitions ja = 1 → jb = 0 it is shown, that the echo polarization differs from that of the second pulse at any conditions.

  4. Effects of thermally grown native oxides on the luminescence properties of compound semiconductors

    NASA Astrophysics Data System (ADS)

    Islam, M. R.; Dupuis, R. D.; Curtis, A. P.; Stillman, G. E.

    1996-08-01

    Data are presented on the luminescence characteristics of GaAs layers adjacent to native-oxide regions derived from epitaxial AlGaAs and InAlP films. The native-oxide ``window'' layers capping the epitaxial structures are formed by the oxidation of the exposed Al0.9Ga0.1As and In0.48Al0.52P cladding layers. Extensive photoluminescence and time-resolved photoluminescence studies performed at 300 K show that both the luminescence intensity and lifetime from GaAs ``active regions'' drop dramatically when the adjacent AlGaAs window layer is oxidized completely. However, there is a marked increase in the efficiency and decay time of the luminescence with the oxidation of InAlP window layers which are grown immediately above the GaAs layer.

  5. Calibration of the Al2O3:C optically stimulated luminescence (OSL) signal for linear energy transfer (LET) measurements in therapeutic proton beams.

    PubMed

    Granville, Dal A; Sahoo, Narayan; Sawakuchi, Gabriel O

    2014-08-01

    Optically stimulated luminescence (OSL) detectors (OSLDs) have shown potential for measurements of linear energy transfer (LET) in proton therapy beams. However, the technique lacks the efficiency needed for clinical implementation, and a faster, simpler approach to LET measurements is desirable. The goal of this work was to demonstrate and evaluate the potential of calibrating Al2O3:C OSLDs for LET measurements using new methods. We exposed batches of OSLDs to unmodulated proton beams of varying LET and calibrated three parameters of the resulting OSL signals as functions of fluence-averaged LET (ϕ-LET) and dose-averaged LET (D-LET). These three parameters included the OSL curve shape evaluated under continuous wave stimulation (CW-OSL), the OSL curve shape evaluated under pulsed stimulation (P-OSL), and the intensity ratio of the two main emission bands in the Al2O3:C OSL emission spectrum (ultraviolet [UV]/blue ratio). To test the calibration, we then irradiated new batches of OSLDs in modulated proton beams of varying LET, and used the OSL signal parameters to calculate ϕ-LET and D-LET under these new test conditions. Using the P-OSL curve shape, D-LET was measured within 5.7% of the expected value. We conclude that from a single 10 s readout (following initial calibration), both the absorbed dose and LET in proton therapy beams can be measured using OSLDs. This has potential future applications in the quality assurance of proton therapy treatment plans, particularly for those that may account for LET or relative biological effectiveness in their optimization. The methods demonstrated in this work may also be applicable to other particle therapy beams, including carbon ion beams. PMID:25029434

  6. Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles

    PubMed Central

    Burunkova, Julia A; Denisiuk, Ihor Yu; Zhuk, Dmitri I; Daroczi, Lajos; Csik, Attila; Kokenyesi, Sándor

    2016-01-01

    Summary Rare-earth-doped optical materials are important for light sources in optoelectronics, as well as for efficient optical amplification elements and other elements of photonics. On the basis of the previously developed method of anhydrous, low-temperature synthesis of Er/Yb oxides from their chlorides we fabricated proper nanoparticles with defined parameters and used them for the development of optically transparent, luminescent polymer nanocomposite with low optical scattering, suitable for direct, light-induced formation of photonic elements. Introduction of preformed gold nanoparticles in such a nanocomposite was also performed and an enhancement of luminescence due to the influence of plasmon effects was detected. PMID:27335752

  7. Fabrication and properties of luminescence polymer composites with erbium/ytterbium oxides and gold nanoparticles.

    PubMed

    Burunkova, Julia A; Denisiuk, Ihor Yu; Zhuk, Dmitri I; Daroczi, Lajos; Csik, Attila; Csarnovics, István; Kokenyesi, Sándor

    2016-01-01

    Rare-earth-doped optical materials are important for light sources in optoelectronics, as well as for efficient optical amplification elements and other elements of photonics. On the basis of the previously developed method of anhydrous, low-temperature synthesis of Er/Yb oxides from their chlorides we fabricated proper nanoparticles with defined parameters and used them for the development of optically transparent, luminescent polymer nanocomposite with low optical scattering, suitable for direct, light-induced formation of photonic elements. Introduction of preformed gold nanoparticles in such a nanocomposite was also performed and an enhancement of luminescence due to the influence of plasmon effects was detected. PMID:27335752

  8. Mechanoresponsive Luminescent Molecular Assemblies: An Emerging Class of Materials.

    PubMed

    Sagara, Yoshimitsu; Yamane, Shogo; Mitani, Masato; Weder, Christoph; Kato, Takashi

    2016-02-01

    The possibility to change the molecular assembled structures of organic and organometallic materials through mechanical stimulation is emerging as a general and powerful concept for the design of functional materials. In particular, the photophysical properties such as photoluminescence color, quantum yield, and emission lifetime of organic and organometallic fluorophores can significantly depend on the molecular packing, enabling the development of molecular materials with mechanoresponsive luminescence characteristics. Indeed, an increasing number of studies have shown in recent years that mechanical force can be utilized to change the molecular arrangement, and thereby the optical response, of luminescent molecular assemblies of π-conjugated organic or organometallic molecules. Here, the development of such mechanoresponsive luminescent (MRL) molecular assemblies consisting of organic or organometallic molecules is reviewed and emerging trends in this research field are summarized. After a brief introduction of mechanoresponsive luminescence observed in molecular assemblies, the concept of "luminescent molecular domino" is introduced, before molecular materials that show turn-on/off of photoluminescence in response to mechanical stimulation are reviewed. Mechanically stimulated multicolor changes and water-soluble MRL materials are also highlighted and approaches that combine the concept of MRL molecular assemblies with other materials types are presented in the last part of this progress report. PMID:26461848

  9. Pickled luminescent silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Boukherroub, R.; Morin, S.; Wayner, D. D. M.; Lockwood, D. J.

    2001-05-01

    In freshly prepared porous Si, the newly exposed silicon-nanostructure surface is protected with a monolayer of hydrogen, which is very reactive and oxidizes in air leading to a loss of luminescence intensity and a degradation of the electronic properties. We report a surface passivation approach based on organic modification that stabilizes the luminescence. This novel 'pickling' process not only augments the desired optoelectronic properties, but also is adaptable to further chemical modification for integration into chemical and biophysical sensors.

  10. Method of measuring luminescence of a material

    DOEpatents

    Miller, Steven D.

    2015-12-15

    A method of measuring luminescence of a material is disclosed. The method includes applying a light source to excite an exposed material. The method also includes amplifying an emission signal of the material. The method further includes measuring a luminescent emission at a fixed time window of about 10 picoseconds to about 10 nanoseconds. The luminescence may be radio photoluminescence (RPL) or optically stimulated luminescence (OSL).

  11. Influence of ZnO nanorod on the luminescent and electrical properties of fluorescent dye-doped polymer nanocomposite

    NASA Astrophysics Data System (ADS)

    Zhang, T.; Xu, Z.; Qian, L.; Tao, D. L.; Teng, F.; Xu, X. R.

    2006-11-01

    The luminescent properties of fluorescent dye-doped polymer dispersed with ZnO nanorods were investigated. Embedding ZnO nanorods in blend film results in a blue-shifted emission of fluorescent dye. It is accounted for in terms of the difference in permittivity between inorganic oxide nano-material and dye-doped polymer. Moreover, polymer light-emitting diodes with the addition of ZnO nanorods showed the lower threshold voltage and the higher charge current and electroluminescence efficiency.

  12. Effect of microwave treatment on the luminescence properties of CdS and CdTe:Cl Single Crystals

    SciTech Connect

    Red’ko, R. A. Budzulyak, S. I.; Korbutyak, D. V.; Lotsko, A. P.; Vakhnyak, N. D.; Demchyna, L. A.; Kalytchuk, S. M.; Konakova, R. V.; Milenin, V. V.; Bykov, Yu. V. Egorov, S. V.; Eremeev, A. G.

    2015-07-15

    The effect of microwave radiation on the luminescence properties of CdS and CdTe:Cl single crystals is studied. It is established that the exposure of these semiconductors to short-term (≤30 s) microwave radiation substantially modifies their impurity and defect structure. The mechanisms of transformation of the defect subsystem of II–VI single crystals upon microwave treatment are discussed. It is shown that the experimentally observed changes are defined by the nonthermal effects of microwave radiation at a power density of 7.5 W cm{sup –2}; at 90 W cm{sup –2}, nonthermal effects are prevailing.

  13. Alkynyl bridged cyclometalated Ir2M2 clusters: impact of the heterometal in the photo- and electro-luminescence properties.

    PubMed

    Fernández-Cestau, Julio; Giménez, Nora; Lalinde, Elena; Montaño, Patricia; Moreno, M Teresa; Sánchez, Sergio; Weber, Michael D; Costa, Rubén D

    2016-02-28

    We report two unprecedent alkynyl bridging cyclometalated clusters [Ir2M2(ppy)4(μ-C[triple bond, length as m-dash]CC6H4-OMe3)4] where M is Ag (2) and Cu (3), which display distinctive luminescence properties. While 2 features a green phosphorescence/electroluminescence nature located at the ppy ligands ((3)LC), 3 shows an orange emission confined to the metals and alkynyl groups having a mixed (3)L'C/(3)L'MCT/(3)MMCT (L' = alkynyl) nature. PMID:26827753

  14. Influence of optical gaps on signal and noise properties of luminescent screen x-ray detectors

    NASA Astrophysics Data System (ADS)

    Koch, Andreas

    2004-05-01

    X-ray detection with luminescent screens requires optical signal transfer as an intermediate step between x-ray detection and conversion to an electronic signal. Luminescent screens may be granular (phosphor screens), structured (e.g. CsI) or transparent (scintillators). The optical signal is imaged with lenses, fibre optics, electron optics or by proximity focussing to an electronic detector. Poor focussing or poor optical contact may degrade the signal and noise transfer characteristics, i.e. modulation transfer function (MTF) and detective quantum efficiency (DQE). The case when x-rays are detected with granular luminescent screens, imaged onto flat panel electronic detectors is considered here. The detector assembly often requires layers of glue or protective thin films creating optical gaps, in which light is spread, hence spatial resolution is degraded. The noise spectrum is not necessarily changed the same way. Its exact shape depends on the dominant noise sources in a given detector configuration under the specific operating conditions: The noise of the primary x-ray quanta, noise aliasing and direct x-ray detection by the electronic detection layer are the main contributions in this investigation. Especially at high spatial frequencies small optical gaps in conjunction with white quantum noise from direct x-ray absorption of the electronic imager degrade DQE: A gap of 40 μm between luminescent screen and detector reduces the DQE by 33% at the Nyquist frequency. This was demonstrated with an a-Si imager of 143-μm pixel size and a Lanex Fine luminescent screen operated at 100 kV.

  15. Slip rate determination along the Southern Dead Sea fault: optically stimulated luminescence, 10Be cosmogenic radionuclide, and 14C ages brought face to face

    NASA Astrophysics Data System (ADS)

    Le Beon, Maryline; Jaiswal, Manoj; Kunz, Alexander; Al-Qaryouti, Mahmoud; Burr, George; Klinger, Yann; Moumani, Khaled; Chen, Yue-Gau; Abdelghafoor, Mohammed; Suppe, John

    2014-05-01

    Active tectonics studies are often limited by difficulties in accurately and precisely dating Late Quaternary alluvial deposits that commonly lack organic matter or date beyond the 14C dating limit. This is illustrated at a site called Fidan, in arid southern Jordan, where a series of alluvial fans are laterally offset by the southern Dead Sea fault. Geodetic, geomorphic and geologic studies converge to a fault slip rate of 5 ± 2 mm/a. Yet, Late Pleistocene slip rate at Fidan cover a wide range due to the dispersion of 10Be cosmogenic radionuclide (CRN) ages. The maximum slip rate since ~100 ka is up to a value of 11 mm/a, possibly suggesting significant variations in fault activity with time. In order to reduce the uncertainty on the Late Pleistocene slip rate and draw further conclusions regarding the fault seismic behavior, we implement complementary dating using optically stimulated luminescence (OSL) techniques on both quartz and K-feldspar minerals and using 14C when possible. OSL measurements include a newly developed technique called post-infra-red infra-red stimulated luminescence at 290°C (pIR290). We extensively sampled surface levels F2 and F4, digging ~50-cm deep pits into the geomorphic surfaces. Annual dose rates were determined in the laboratory from both geochemical analysis of the sediment and gamma-ray spectrometry. Due to sediment heterogeneity, we consider gamma-ray spectrometry as more reliable because it is based on a larger volume of sediment. Quartz OSL ages and preliminary pIR290 results on K-feldspars give consistent Early Holocene ages of 9-14 ka for F2, also in agreement with a 14C age of 13 ka from a landsnail shell. 10Be CRN exposure ages on F2 were significantly older, with 37 ± 4 ka, probably due to inheritance. On F4, 10Be CRN exposure ages showed a scattered distribution, from ~50 ka to ~120 ka, with most samples comprised in the mean interval of 87 ± 26 ka. Quartz OSL ages from 5 locations on F4 are comprised between 32 ± 3

  16. Crystal structures and luminescent properties of lanthanide nitrate coordination polymers with structurally related amide type bridging podands

    SciTech Connect

    Wang, Qing; Yan, Xuhuan; Zhang, Hongrui; Liu, Weisheng; Tang, Yu; Tan, Minyu

    2011-01-15

    A one-dimensional linear chain coordination polymer [ErL{sup I}(NO{sub 3}){sub 3}(CH{sub 3}CO{sub 2}Et)]{sub n} (L{sup I}=1,2-bis{l_brace}[(2'-furfurylaminoformyl)phenoxyl]methyl{r_brace}benzene) and a one-dimensional zig-zag coordination polymer {l_brace}[TbL{sup II}(NO{sub 3}){sub 3}(H{sub 2}O)].(H{sub 2}O){r_brace}{sub n} (L{sup II}=1,2-bis{l_brace}[2'-(2-pyridylmethylaminoformyl)phenoxyl]methyl{r_brace}benzene) were assembled by two structurally related bridging podands L{sup I} and L{sup II} which have uniform skeleton and different terminal groups. In {l_brace}[TbL{sup II}(NO{sub 3}){sub 3}(H{sub 2}O)].(H{sub 2}O){r_brace}{sub n}, the neutral chains were linked by the hydrogen bonding interactions between the free and coordinated water molecules from two different directions to interpenetrate into a 3D supramolecular structure. At the same time, the luminescent properties of the solid Tb(III) nitrate complexes of these podands were investigated at room temperature. The lowest triplet state energy levels T{sub 1} of the podands L{sup I} and L{sup II} indicate that the triplet state energy levels of the antennae are both above the lowest excited resonance level of {sup 5}D{sub 4} of Tb{sup 3+} ion. Thus the absorbed energy could be transferred from ligands to the central Tb{sup 3+} ions. And the influence of the hydrogen bonding on the luminescence efficiencies of the coordination polymers was also discussed. -- Graphical Abstract: Two one-dimensional lanthanide coordination polymers were assembled by two structurally related bridging podands, and the effects of the structures on luminescent properties of the solid Tb(III) nitrate complexes were investigated. Display Omitted Research highlights: > Two structurally related amide type bridging ligands were designed and synthesized. > Two one dimensional lanthanide nitrate coordination polymers were obtained. > The structure effects on luminescent properties of the terbium complexes were discussed.

  17. Ex-Situ Stress Measurements in Polycrystalline Ceramics Using Photo-Stimulated Luminescence Spectroscopy and High-Energy X-Rays

    SciTech Connect

    Raghavan, Seetha; Imbrie, Peter K.

    2009-09-14

    The photo-stimulated luminescence spectroscopy (PSLS) technique provides the means to establish stress dependencies of the well-known R-line peak positions in polycrystalline alumina. The uniaxial compression tests presented in this paper, which determine the coefficients describing this piezospectroscopic (PS) behavior, tackle two previously unexplored areas. Firstly, the vibronic band peaks in the emission spectrum are introduced here, and the PS coefficients of several peaks within these bands are established. These results set the foundation for the exploitation of vibronic band peakshifts, along with the R-lines, in order to provide the non-symmetric components of the stress tensor and therefore the measurement of the complete stress state in polycrystalline alumina. Secondly, high-energy X-rays serve as an ex-situ stress measurement method upon which the optical fluorescence shifts are based, thereby advancing the accuracy of PS coefficient determination in a unique approach. The results of PSLS and synchrotron X-ray experiments are presented here and used in conjunction to reveal new information on the PS behavior of polycrystalline alumina.

  18. Luminescence properties of nanosized Y3Al5O12Ce3+ phosphor synthesized by liquid phase precursor method.

    PubMed

    Jo, Deok Su; Linh, Dang Thi My; Masaki, Takaki; Yoon, Dae Ho

    2014-11-01

    A novel liquid-phase precursor (LPP) method using precursor nanoparticles (PNs) is proposed to synthesize yttrium aluminum garnet nano-sized phosphor (Y3Al5O12:Ce3+, nano-YAG:Ce) at 1100-1500 degrees C for 5 h. The influences of the heat-treatment and morphology properties of the PNs on the luminescence properties of the nano-YAG:Ce phosphor were investigated. Nano-YAG:Ce phosphor with better morphology and high luminescence efficiency was obtained with heat-treatment of PNs at 1200 degrees C. With more heat treatment, the phosphor particles agglomerated more, and the emission intensity increased. The broad photoluminescence excitation (PLE) and photoluminescence (PL) spectra of the nano-YAG:Ce phosphor were centered at 341 nm and 466 nm, respectively, due to the 4f --> 5d energy transition. The nonsymmetrical emission spectra range of 470-750 nm was centered at 529.2 nm due to the 5d --> 4f energy transition of Ce3+. The nano-YAG:Ce, and micro-YAG:Ce phosphors synthesized by the LPP method using precursor microparticles (PMs) and PNs were investigated and compared. PMID:25958522

  19. Electrical, luminescent, and deep trap properties of Si doped n-GaN grown by pendeo epitaxy

    NASA Astrophysics Data System (ADS)

    Polyakov, A. Y.; Smirnov, N. B.; Yakimov, E. B.; Lee, In-Hwan; Pearton, S. J.

    2016-01-01

    Electrical and luminescent properties and deep trap spectra of Si doped GaN films grown by maskless epitaxial lateral overgrowth (MELO) are reported. The dislocation density in the wing region of the structure was 106 cm-2, while in the seed region it was 108 cm-2. The major electron traps present had activation energy of 0.56 eV and concentrations in the high 1015 cm-3 range. A comparison of diffusion length values and 0.56 eV trap concentration in MELO GaN and epitaxial lateral overgrowth (ELOG) GaN showed a good correlation, suggesting these traps could be effective in carrier recombination. The doped MELO films were more uniform in their electrical properties than either ELOG films or undoped MELO films. We also discuss the differences in deep trap spectra and luminescence spectra of low-dislocation-density MELO, ELOG, and bulk n-GaN samples grown by hydride vapor phase epitaxy. It is suggested that the observed differences could be caused by the differences in oxygen and carbon contamination levels.

  20. Structural and luminescence properties of Y(2-x)GeMoO8:REx (RE = Eu, Tb) phosphors.

    PubMed

    Li, Naixu; Zhou, Jiancheng; Sun, Yueming

    2014-08-01

    Y(2-x)GeMoO8:REx (RE = Eu, Tb) phosphors were synthesized using a facile sol-gel method. The morphology and structure of the phosphors were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray diffraction (XRD); while their luminescent properties were investigated by photoluminescence (PL) spectrometry. Our results reveal that all of these Y(2-x)GeMoO8:REx (RE = Eu, Tb) phosphors adopted the tetragonal phase, belonging to Scheelite (CaWO4 ) structure. The obtained YGeMoO8:Eu phosphors exhibit a strong emission in the red light range which can be assigned to the (5)D0  → (7)F2 transition of Eu(3+) when it is excited at 459 nm. Under 392 and 489 nm excitation, the YGeMoO8:Tb phosphors present predominant green emission ((5)D4  → (7)F5) at 540 nm. The highest emission of the phosphors can be achieved by adjusting the doping concentration to be 0.25 for Eu(3+) and 0.15 for Tb(3+), respectively. The promising luminescence properties of these materials indicate that they can be potentially applied to white-light-emitting diodes. PMID:23832824

  1. Electrical and luminescent properties and deep traps spectra in GaN nanopillar layers prepared by dry etching

    NASA Astrophysics Data System (ADS)

    Polyakov, A. Y.; Jeon, Dae-Woo; Smirnov, N. B.; Govorkov, A. V.; Kozhukhova, E. A.; Yakimov, E. B.; Lee, In-Hwan

    2012-10-01

    Electrical properties, microcathodoluminescence spectra, and spectra of deep traps were studied for nanopillar structures prepared by dry etching of undoped GaN films using natural masks formed by Ni nanoparticles. It is shown that as-prepared nanopillar structures have low bandedge intensity, very high leakage current of Schottky diodes, their electrical properties are determined by 0.2 eV electron traps or, after etching in aqua regia, 0.14 eV electron traps that are commonly associated with radiation defects. Deep levels transient spectroscopy spectra measured after aqua regia etching are dominated by 1 eV electron traps, other common radiation defects. Annealing at 600 °C is instrumental in eliminating the 0.2 eV and 0.14 eV electron traps, but not the 1 eV traps. A higher temperature annealing at 900 °C is required for strongly suppressing the latter and increasing the bandedge luminescence peak magnitude by 2 times compared to control sample. The best results in terms of luminescence efficiency increase are produced by additional etching in aqueous solution of KOH, but subsequent etching in aqua regia is necessary to suppress excessive surface leakage due to surface contamination by the KOH treatment.

  2. Luminescence properties and compositions of contaminating inorganic minerals separated from gamma-irradiated fresh and white ginsengs from different areas

    PubMed Central

    Ahn, Jae-Jun; Akram, Kashif; Jeong, Mi-Seon; Kwak, Ji-Young; Park, Eun-Joo; Kwon, Joong-Ho

    2013-01-01

    Gamma-irradiation (0-7 kGy) of ginseng is permitted in Korea for the purpose of microbial decontamination; with strict labeling, traceability and monitoring requirements. An identification study was conducted to determine the photostimulated-luminescence (PSL) and thermoluminescence (TL) properties of gamma-irradiated fresh and white ginsengs cultivated in different areas. Dosedependent PSL-based screening was possible for white ginseng samples; however, inappropriate results from non-irradiated fresh ginseng samples were obtained, showing intermediate (700 to 5,000) or positive (T2 >5,000, irradiated) PSL counts due to the abundance of minerals on the surfaces of the samples. TL analysis of separated minerals from all non-irradiated samples gave TL glow curves of low intensity with a maximum peak after 300℃. However, well-defined irradiation-specific (high intensity with a maximum peak at about 200℃) glow curves were observed for all the irradiated samples, regardless of their type and origins. TL ratios (first glow curve /second glow curve) were also determined to confirm the irradiated (>0.1) and non-irradiated (<0.1) results. SEM-EDX (scanning electron microscope-energy dispersive X-ray) and XRD (X-ray diffraction) spectroscopic analyses showed that feldspar and quartz minerals were the main source for the typical radiation-specific luminescence properties. PMID:24235863

  3. Investigation of luminescent properties of LaF3:Nd3+ nanoparticles

    NASA Astrophysics Data System (ADS)

    Wyrwas, Marek; Miluski, Piotr; Zmojda, Jacek; Kochanowicz, Marcin; Jelen, Piotr; Sitarz, Maciej; Dorosz, Dominik

    2015-09-01

    Lanthanum fluoride nanoparticles doped with Nd3+ ions obtained via solvothermal method have been presented. Doped nanoparticles were prepared in two-step method. Firstly rare-earth chlorides were synthesized from oxides and then they were used to prepare LaF3 particles. The luminescence spectra shows typical for crystalline materials Stark splitting at 880 nm corresponding 4F3/2 to 4I9/2 level transition and 1060 nm matching 4F3/2 to 4I11/2 level transition. The highest luminescence intensity was achieved for sample doped with 0.75% wt. of Nd3+, and the longest decay time for sample doped with 0.5% wt. which reached 328 μs. The XRD pattern analysis confirmed that obtained material consists of crystalline LaF3, the grain size was estimated from Sherrer's formula and equaled about 25nm.

  4. Spectral Luminescent Properties of the Glycine Molecule in a Gas Discharge

    NASA Astrophysics Data System (ADS)

    General, A. A.; Migovich, M. I.; Kelman, V. A.; Zhmenyak, Yu. V.; Zvenigorodsky, V. V.

    2016-01-01

    We have experimentally studied the luminescence spectra of glycine powder in the plasma of a repetitively pulsed longitudinal discharge in argon-glycine and helium-glycine mixtures. We have identified the main fragments of the glycine molecule emitting in the 200-1000 nm region. The emitting molecules due to fragmentation of glycine and dissociation of the carboxyl (-COOH) and amino (-NH2) groups are nitrogen, carbon monoxide, and cyanogen molecules.

  5. Optically stimulated luminescence (OSL) response of Al2O3:C, BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors.

    PubMed

    Kumar, Pratik; Bahl, Shaila; Sahare, P D; Kumar, Surender; Singh, Manveer

    2015-12-01

    This paper investigates the optically stimulated luminescence (OSL) response of BaFCl:Eu and K2Ca2(SO4)3:Eu phosphors for different doses and bleaching durations. The results have also been compared with the commercially available Landauer Al2O3:C (Luxel®) dosemeter. Nanocrystalline K2Ca2(SO4)3:Eu is known to be a sensitive thermoluminescent phosphor, but its OSL response is hardly reported. At first, pellets of nanocrystalline K2Ca2(SO4)3:Eu powder were prepared by adding Teflon as a binder. Their OSL signal was compared with that of the material in pure form, i.e. without adding the binder (in 100:1 ratio). It was observed that adding the binder does not appreciably affect the OSL intensity. On comparison with the commercially available Al2O3:C from Landauer, it was found that K2Ca2(SO4)3:Eu is around 15 times less sensitive than Al2O3:C. 'Homemade' BaFCl:Eu phosphor has also been studied. The intensity of BaFCl:Eu was ∼20 times more than the standard Al2O3:C dosemeter and ∼200 times more sensitive than K2Ca2(SO4)3:Eu in the dose range of 13-200 cGy. OSL dosemeters are believed to give luminescence signal even if they are read before, i.e. multiple reading may be possible under suitable conditions after single exposure. This was also checked for all the prepared dosemeters and it was found that Al2O3:C showed the least decrease of <2 %, followed by BaFCl:Eu of 15 % and K2Ca2(SO4)3:Eu with 20 %. Finally, Al2O3:C and BaFCl:Eu phosphors were also studied for their optical bleaching durations to which the respective signals get completely removed so that the phosphor can be re-used. It was observed that BaFCl:Eu is bleached faster and more easily than Al2O3:C. PMID:25646524

  6. Synthesis and luminescence properties of ZnGa2O4 spinel doped with Co2+ and Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Duan, Xiulan; Yu, Fapeng; Wu, Yuanchun

    2012-11-01

    ZnGa2O4 nanopowders doped with Co2+ and Eu3+ ions, including dual doping, have been synthesized by citrate sol-gel method, and characterized by X-ray powder diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). Results show that ZnGa2O4 spinels were produced by calcining the gel above 500 °C, with the crystallite size of 16-30 nm in the temperature range of 500-900 °C. Co2+ ions are located at the tetrahedral sites of ZnGa2O4 spinel by replacing Zn2+, and Eu3+ ions are incorporated in the defect regions at the grain boundaries. The emission spectra of Eu-doped ZnGa2O4 nanopowders display an intense emission at 615 nm belonging to 5D0-7F2 transition of Eu3+ ions. With the introduction of Co into Eu-doped ZnGa2O4, the emission intensity at 615 nm decreases, while the luminescence at 680 nm due to tetrahedral Co2+ increases. The result indicates that the energy transfer occurred from Eu3+ to Co2+ ions. The energy transfer was also studied by the luminescence decay behavior. The emission of Co and Eu Co-doped ZnGa2O4 also changed with annealing temperature. The luminescence properties of the doped ZnGa2O4 nanopowders can be controlled by the variation of Co and Eu doping concentration and annealing temperature.

  7. Fabrication and upconversion luminescence properties of YF3:Er3+ hollow nanofibers via monoaxial electrospinning combined with fluorination method.

    PubMed

    Li, Dan; Dong, Xiangting; Yu, Wensheng; Wang, Jinxian; Liu, Guixia

    2014-06-01

    YF3:Er3+ hollow nanofibers were successfully fabricated via fluorination of the relevant Y2O3:Er3+ hollow nanofibers which were obtained by calcining the electrospun PVP/[Y(NO3)3 + Er(NO3)3] composite nanofibers. The morphology and properties of the products were investigated in detail by X-ray diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), and fluorescence spectrometer. YF3:Er3+ hollow nanofibers were pure orthorhombic phase with space group Pnma and were hollow-centered structure with the mean diameter of 172 +/- 23 nm, and YF3:Er3+ hollow nanofibers were composed of nanoparticles with the diameter ranging from 30 nm to 50 nm. Upconversion emission spectrum analysis manifested that YF3:Er3+ hollow nanofibers emitted strong green and weak red upconversion emission centering at 524 nm, 543 nm and 653 nm, respectively. The green emissions and the red emission were respectively originated from 2H11/2/4S3/2 --> 4I15/2 and 4F9/2 --> 4I15/2 energy levels transitions of the Er3+ ions. Moreover, the emitting colors of YF3:Er3+ hollow nanofibers were located in the green region in CIE chromaticity coordinates diagram. The luminescent intensity of YF3:Er3+ hollow nanofibers was increased remarkably with the increasing doping concentration of Er3+ ions. The possible formation mechanism of YF3:Er3+ upconversion luminescence hollow nanofibers was also discussed. This preparation technique could be applied to prepare other rare earth fluoride upconversion luminescence hollow nanofibers. PMID:24738372

  8. Characterisation of the luminescence properties of BAM:Eu2+ particles as a tracer for thermographic particle image velocimetry

    NASA Astrophysics Data System (ADS)

    Fond, Benoit; Abram, Christopher; Beyrau, Frank

    2015-12-01

    Thermographic phosphor particles are seeded into the flow as tracers for simultaneous temperature and velocity measurements in fluids. Several studies using different phosphors as gas-phase tracers have been published in recent years. However, little is known about their emission characteristics when they are dispersed as individual particles in the fluid. In this paper, the luminescence properties of BAM:Eu2+ particles, a phosphor with favourable characteristics (short luminescence lifetime, blue emission spectrum, high quantum efficiency), are thoroughly investigated in the gas phase. Using a recently developed particle-counting tool, the emission intensity per particle is measured over a wide range of conditions, including for various temperatures from 300 to 920 K, in air and in pure nitrogen. The luminescence emission per particle is shown to drop with temperature, but to be insensitive to the seeding density and to the oxygen content over the tested range. Together with a spectroscopic study, and a statistical error analysis, these results are used to predict the temperature precision of the technique under various conditions for different filter combinations and to assess the current upper temperature limit of this phosphor for practical applications. Potential additional sources of uncertainty are also investigated, including cross-dependencies of the measured intensity ratio on the seeding density, excitation fluence and oxygen partial pressure in the gas phase. Only a weak dependence on the laser fluence is observed, while the measured intensity ratio is shown to be insensitive to both seeding density and the oxygen volume fraction. Finally, the saturation behaviour of the phosphorescence emission is examined, through theoretical considerations and measurements performed with different excitation schemes in an attempt to increase signal levels. In conclusion, this paper confirms that BAM:Eu2+ is a very suitable tracer for measurements in turbulent flows

  9. Photoluminescence and long persistent luminescence properties of a novel green emitting phosphor Sr3TaAl3Si2O14:Tb3+

    NASA Astrophysics Data System (ADS)

    Xue, Feihong; Hu, Yihua; Ju, Guifang; Chen, Li; He, Miao; Wang, Tao; Jin, Yahong; Zhang, Shaoan; Lin, Jun

    2016-06-01

    A series of green emitting persistent phosphors Sr3TaAl3Si2O14:Tb3+ were synthesized via a conventional solid-state reaction method. These phosphors show a green persistent luminescence dominated at ~542 nm at room temperature after irradiated by 254 nm ultraviolet light for minutes. X-ray diffraction, scanning micrograph images, photoluminescence spectra, decay curves, afterglow spectra and thermal luminescence were performed to investigate the physical properties of the persistent phosphors. The influence of Tb3+ concentrations on the photoluminescence and long persistent luminescence properties was studied. The optimal concentration of Tb3+ ions for the best afterglow characteristic was experimentally to be 0.5 mol%. A feasible model was proposed on the basis of experimental results to discuss mechanism of long afterglow in Sr3TaAl3Si2O14:Tb3+ in detail.

  10. Synthesis and luminescent properties of Sr3Al2O5Cl2: Eu2+, Dy3+ rod-like nanocrystals

    NASA Astrophysics Data System (ADS)

    Wang, Zhengliang; Zhang, Qiuhan; Rong, Meizhu; Tan, Huiying; Wang, Qin; Zhou, Qiang; Chen, Guo

    2016-08-01

    White long afterglow phosphor with nano-rods, Sr3Al2O5Cl2: Eu2+, Dy3+, has been successfully synthesized by the solid state reaction. Their structure, morphology, scanning electron microscopy, luminescent properties and long afterglow properties were investigated by X-ray diffraction, transmission electron microscopy luminescence spectra and the luminescence decay curve. The obtained phosphor Sr3Al2O5Cl2: Eu2+, Dy3+ exhibits two broad emission bands, which are located at ∼445 nm and ∼590 nm, respectively. White light can be observed from this phosphor with appropriate CIE values (x = 0.357, y = 0.332). The white afterglow duration of this phosphor is about 0.5 h (>0.35 mcd/m2).

  11. Investigation of luminescence and spectroscopic properties of Nd3+ions in cadmium alkali borate glasses

    NASA Astrophysics Data System (ADS)

    Mohan, Shaweta; Thind, Kulwant Singh

    2016-07-01

    Neodymium doped cadmium alkali borate glasses having composition 20CdOsbnd 20R2Osbnd 59.5H3BO3sbnd 0.5Nd2O3; (R = Li, Na and K) were prepared by conventional melt-quenching technique. The amorphous nature of the glasses was confirmed by X-ray diffraction studies. The physical properties such as density, refractive index, molar volume, rare earth ion concentration etc. were determined. Optical absorption and fluorescence spectra were recorded. The Judd-Ofelt theory was applied on the optical absorption spectra of the glasses to evaluate the three phenomenological intensity parameters Ω2, Ω4 and Ω6. These parameters were in turn used to predict the radiative properties such as the radiative transition probability (A), radiative lifetime (τR) and branching ratio (βR) for the fluorescent levels of Nd3+ ion in the present glass series. The lasing efficiency of the prepared glasses has been characterized by the spectroscopic quality factor (Ω4/Ω6), the value of which is in the range of 0.2-1.5, typical for Nd3+ in different laser hosts. The variation of Ω2 with the change in alkali oxide has been attributed to the changes in the asymmetry of the ligand field at the rare earth ion site. The shift of the hypersensitive bands, study of the oscillator strengths and the variation of the spectral profile of the transition 4I9/2 → 4F7/2 + 4S3/2 indicate a maximum covalency of Ndsbnd O bond for glass with potassium ions. From the fluorescence spectra, peak wavelength (λp), effective line widths (Δλeff) and stimulated emission cross-section (σp) have been obtained for the three transitions 4F3/2 → 4I9/2,4F3/2 → 4I11/2 and4F3/2 → 4I13/2 of Nd3+ ion. The relatively high values of σp obtained for Nd3+ in present glass system suggest that these materials can be considered as suitable candidates for laser applications. The glass with potassium ions shows the highest value of the stimulated emission cross-section.

  12. Structure-Triggered High Quantum Yield Luminescence and Switchable Dielectric Properties in Manganese(II) Based Hybrid Compounds.

    PubMed

    Wang, Zhong-Xia; Li, Peng-Fei; Liao, Wei-Qiang; Tang, Yuanyuan; Ye, Heng-Yun; Zhang, Yi

    2016-04-01

    Two new manganese(II) based organic-inorganic hybrid compounds, C11 H21 Cl3 MnN2 (1) and C11 H22 Cl4 MnN2 (2), with prominent photoluminescence and dielectric properties were synthesized by solvent modulation. Compound 1 with novel trigonal bipyramidal geometry exhibits bright red luminescence with a lifetime of 2.47 ms and high quantum yield of 35.8 %. Compound 2 with tetrahedral geometry displays intense long-lived (1.54 ms) green light emission with higher quantum yield of 92.3 %, accompanied by reversible solid-state phase transition at 170 K and a distinct switchable dielectric property. The better performance of 2 results from the structure, including a discrete organic cation moiety and inorganic metal anion framework, which gives the cations large freedom of motion. PMID:26864910

  13. A novel cobalt (I) coordination polymer with mixed thiocyanate and quinoline ligands: crystal structure, magnetism and luminescent properties.

    PubMed

    Li, Lei; Chen, Shuai; Zhou, Rui-Min; Bai, Yan; Dang, Dong-Bin

    2014-01-01

    A new Co(I) one-dimensional coordination polymer [Co(SCN)(ql)]n (ql=quinoline) (1) has been synthesized and characterized by IR, elemental analysis, TG technique and X-ray crystallography. Co(I) atom has a distorted trigonal pyramidal N2S2 (1) environment with two S atoms and one N atom from three μ-1,1,3-thiocyanate bridge ligands and one N atom from ql ligand. Two S atoms from two μ-1,1,3-SCN- bridging ligands bridge two centers to obtain bimetallic 4-membered ring. Adjacent 4-membered rings are linked by a pair of μ-1,1,3-SCN- bridging ligands to form a 1D stair-case like chain. The luminescent properties and magnetic properties of the polymer 1 were investigated in the solid state. PMID:24211622

  14. Preparation and luminescent properties of lanthanide (Eu3+ and Tb3+) complexes grafted to 3-aminopropyltriethoxysilane by covalent bonds

    NASA Astrophysics Data System (ADS)

    Zhang, Wenjun; Wang, Haiyan

    2015-12-01

    A novel precursor PMA-Si was synthesized by modifying 1,2,4,5-benzene-tetracarboxylic acid (PMA) with 3-aminopropyltriethoxysilane (APTES). Then the hybrids were prepared by PMA-Si coordinating to lanthanide ions (Eu3+ and Tb3+) in sol-gel process. In order to improve luminescent efficiency, 1,10-Phenanthroline (Phen) was introduced to the system as the second ligand. As-prepared compounds in sol condition were coated on quartz plates to form a layer of thin film, which was different from other similar hybrids. The properties of the hybrids were characterized by FT-IR, fluorescence spectra, TG and SEM. The results showed that the obtained materials enhanced thermal stability, mechanical resistances, waterproofness as well as machining properties.

  15. Effects of Eu substituting positions and concentrations on luminescent, dielectric, and magnetic properties of SrTiO3 ceramics

    NASA Astrophysics Data System (ADS)

    Jiang, Chunge; Fang, Liang; Shen, Mingrong; Zheng, Fengang; Wu, Xinglong

    2009-02-01

    The structural, luminescent, dielectric, and magnetic properties of multifunction Eu3+-doped SrTiO3 (STO) ceramics were investigated at room temperature. Three different charge compensation mechanisms were realized by substituting Eu ion at different sites. It was found that the multifunction properties of the samples strongly depended on the substituting positions of Eu ion. Compared with Eu substitution at Sr or Ti site samples, the photoluminescence intensities and dielectric constant of both Sr and Ti sites substituted samples were obviously enhanced, mainly ascribed to the small lattice distortion and unique charge compensation mechanism. A linear magnetization-magnetic field behavior revealed the paramagnetic nature of the Eu3+ doped STO and was sensitive to the Eu doping concentrations.

  16. Luminescence and scintillation properties of La- and La,Ag-doped CsPbCl3 single crystals

    NASA Astrophysics Data System (ADS)

    Watanabe, Kei; Koshimizu, Masanori; Yanagida, Takayuki; Fujimoto, Yutaka; Asai, Keisuke

    2016-02-01

    We analyzed the luminescence and scintillation properties of CsPbCl3 single crystals. La and Ag were chosen as the dopants, although Ag proved to have little effect on the scintillation properties. In the photoluminescence spectra, in addition to the free exciton band at 425 nm, an additional band was observed at 440 nm at low temperatures for the La-doped crystals. The scintillation spectrum of the undoped crystal was composed of the free exciton band and a broad band at 600 nm, which is ascribed to lattice defects. The La doping strongly suppressed both the broad band and the slow scintillation component, which is ascribed to the emission at lattice defects.

  17. Hydrothermal approach for the shape-selective SrSO4:Eu2+ microcrystals and its luminescence properties

    NASA Astrophysics Data System (ADS)

    Di, Qiumei; Han, Liu; Xu, Qiguang; Sun, Guangchao; Sun, Jiayue

    2015-03-01

    Electron trapping materials SrSO4:Eu2+ with various sizes and shapes were prepared by hydrothermal method with the assistance of fatty alcohol polyoxyethylene (3) ether (AEO-3) aqueous solution. Changing the molar ratios of [Sr2+]/[SO4 2-], the dendrites varied from needle, rod to octagonal and hexagonal disk architectures with sizes about 500 nm-4 μm width and 4-10 μm length. The growth mechanics of the particles was discussed to obtain a better understanding on their formation process. In the photoluminescence property investigations of SrSO4:Eu2+, the observed broadband was well identified with the electronic transition configurations of Eu2+. The thermal stability and electron trapping luminescence properties were also characterized.

  18. Synthesis, characterization and luminescent properties of europium complexes with 2,4,6-tris-(2-pyridyl)-s-triazine as highly efficient sensitizers.

    PubMed

    Kang, Jie; Chen, Ying-Nan; Wang, Ai-Ling; Li, Hai-Yan; Qu, Yan-Rong; Zhang, Hai-Xia; Chu, Hai-Bin; Zhao, Yong-Liang

    2015-12-01

    Using 2,4,6-tris-(2-pyridyl)-s-triazine (TPTZ) as a neutral ligand, and p-hydroxybenzoic acid, terephthalic acid and nitrate as anion ligands, five novel europium complexes have been synthesized. These complexes were characterized using elemental analysis, rare earth coordination titrations, UV/vis absorption spectroscopy and infrared spectroscopy. Luminescence spectra, luminescence lifetime and quantum efficiency were investigated and the mechanism discussed in depth. The results show that the complexes have excellent emission intensities, long emission lifetimes and high quantum efficiencies. The superior luminescent properties of the complexes may be because the triplet energy level of the ligands matches well with the lowest excitation state energy level of Eu(3+). Moreover, changing the ratio of the ligands and metal ions leads to different luminescent properties. Among the complexes, Eu2(TPTZ)2(C8H4O4)(NO3)4(C2H5OH)·H2O shows the strongest luminescence intensity, longest emission lifetime and highest quantum efficiency. PMID:25829339

  19. Versatile lanthanide-azide complexes with azide/carboxylate/hydroxy mixed bridged chain exhibiting magnetic and luminescent properties

    SciTech Connect

    Wang Haichao; Xue Min; Guo Qian; Zhao Jiongpeng; Liu Fuchen; Ribas, Joan

    2012-03-15

    Two new lanthanide-azide complexes, [Ln{sub 2}(N{sub 3})(isonic){sub 2}(OH){sub 3}(Hisonic)(H{sub 2}O)]{sub n} (Ln=Yb for 1 and Tb for 2, isonic=isonicotinate), were obtained in hydrothermal condition. X-ray diffraction analysis indicated the two complexes are isomorphic chain structure in which the Ln{sup III} ions are mixed bridged by the azide anions, hydroxyl anions and carboxylate groups of the isonicotinate ligands. Further studies indicated weak antiferromagnetic interactions between the Ln{sup III} ions in 1 and 2, and complex 2 exhibit green sensitized Luminescent character of Tb{sup III} ion. - Graphical abstract: Two new 1D lanthanide-azide complexes, [Ln{sub 2}(N{sub 3})(isonic){sub 2}(OH){sub 3}(Hisonic)(H{sub 2}O)]{sub n} (Ln=Yb{sup III} for 1 and Tb{sup III} for 2, isonic=isonicotinate), were synthesized by hydrothermal reaction and exhibit interesting magnetism and fluorescence properties. Highlights: Black-Right-Pointing-Pointer The research provided a new method for synthesizing lanthanide-azide complexes. Black-Right-Pointing-Pointer The complexes have an interesting azide/hydroxyl/carboxylate mixed bridged1D chain structure. Black-Right-Pointing-Pointer The antiferromagnetic coupling between the complexes and 2 displays green luminescence.

  20. Molten-salt synthesis and composition-dependent luminescent properties of barium tungsto-molybdate-based solid solution phosphors

    NASA Astrophysics Data System (ADS)

    Xiang-Hong, He; Zhao-Lian, Ye; Ming-Yun, Guan; Ning, Lian; Jian-Hua, Sun

    2016-02-01

    Pr3+-activated barium tungsto-molybdate solid solution phosphor Ba(Mo1-zWz)O4:Pr3+ is successfully fabricated via a facile molten-salt approach. The as-synthesized microcrystal is of truncated octahedron and exhibits deep-red-emitting upon blue light excitation. Powder x-ray diffraction and Raman spectroscopy techniques are utilized to investigate the formation of solid solution phosphor. The luminescence behaviors depend on the resulting composition of the microcrystals with fixed Pr3+-doping concentration, while the host lattices remain in a scheelite structure. The forming solid solution via the substitution of [WO4] for [MoO4] can significantly enhance its luminescence, which may be due to the fact that Ba(Mo1-zWz)O4:Pr3+ owns well-defined facets and uniform morphologies. Owing to its properties of high phase purity, well-defined facets, highly uniform morphologies, exceptional chemical and thermal stabilities, and stronger emission intensity, the resulting solid solution phosphor is expected to find potential applications in phosphor-converted white light-emitting diodes (LEDs). Project supported by the Construction Fund for Science and Technology Innovation Group from Jiangsu University of Technology, China, the Key Laboratory of Atmospheric Environment Monitoring and Pollution Control, China (Grant No. KHK1409), the Priority Academic Program Development of Jiangsu Higher Education Institutions, China, and the National Natural Science Foundation of China (Grant No. 21373103).

  1. Single pot synthesis of pyridine-N-oxide based polymeric complexes of cadmium and manganese: Crystal structure and luminescence property

    NASA Astrophysics Data System (ADS)

    Mondal, Sandip; Guha, Averi; Suresh, Eringathodi; Jana, Atish Dipankar; Banerjee, Arpita

    2012-12-01

    Two new polymeric complexes of cadmium(II) and manganese(II) with Pyridine-N-oxide (pyo) mediated by thiocyanate and dicyanamide (dca) anions have been synthesized and characterized by X-ray single crystal structure analysis. The structural analyses reveal that complexes [Cd(pyo)2(SCN)2]n (1) and [Mn(pyo)2(dca)2]n (2) [where, pyo = pyridine-N-oxide; dca = dicyanamide] are 2D coordination polymers. In complex 1 hexa-coordinated Cd(II) centers posses distorted octahedral coordination environments. Each Cd(II) is coordinated by four SCN- in end to end fashion forming a zigzag chain and two pyo monodentate ligands bridge two adjacent Cd(II) centers leading to a two-dimensional sheet structure. In complex 2 hexa-coordinated Mn(II) centers posses octahedral coordination environments. The coordination polymer constitute a 2D polymeric sheet and has a (4, 4) grid network architecture Successive stacking of coordination polymeric sheets are enforced by inter layer OH⋯O and OH⋯N hydrogen bonding. The luminescence properties of these two polynuclear complexes in solid state were studied and complex 1 exhibits higher luminescence intensity than 2.

  2. Synthesis and Luminescent Properties of CaSnO3:Eu Nanopowder Prepared by a Sol-Gel Route.

    PubMed

    Fu, Xiaoyan; Zhao, Tuyuan; Zhang, Yan; Chen, Yibin; Zhang, Hongwu

    2016-04-01

    Luminescent properties of nanocrystalline CaSnO3:1%Eu have been investigated in order to develop novel red phosphors. The results indicate that high-quality nanoparticles with controlled stoichiometry and microstructure were prepared by a sol-gel method using citric acid and EDTA as complexes. There are two broad excitation bands located at 240 and 270 nm existing in the excitation spectrum in addition to the characteristic excitation peaks of Eu3+. Further investigations show that the excitation band located at 240 nm can be assigned to the host absorption while the Eu-O charge transfer is responsible for the 270 nm excitation band. These results indicate that the host can efficiently transfer energy to the Eu3+ ions. The more important is that since the symmetry of Eu3+ ions is lower, the pure red emission (5D9 --> 7F2 transition located at 618 nm) is predominant over all the emission. This means CaSnO3:Eu is a potential candidate for red luminescent materials. PMID:27451726

  3. Upconversion luminescence properties of Er(3+)-Bi3+ codoped CaSnO3 nanocrystals with perovskite structure.

    PubMed

    Pang, Xinling; Zhang, Ying; Ding, Linghong; Su, Zhaohui; Zhang, W F

    2010-03-01

    New phosphor nanocrystals of ASnO3:Er3+ (A = Ca, Sr, and Ba) and CaSnO3:Er(3+)-Bi3+ were prepared by a hydrothermal method. Their structures were examined by X-ray diffraction and Raman spectroscopy. Upconversion luminescence properties of the Er3+ ions in these host materials were investigated upon excitation at 980 nm. Green emission bands of Er3+ around 528 and 545 nm were more favorable in CaSnO3 than in SrSnO3 and BaSnO3. This was interpreted in terms of a crystal structural distortion and configuration coordinate model. The investigation of the upconversion luminescence of Er(3+)-Bi3+codoped CaSnO3 nanocrystals indicates that Bi3+ ions could largely sensitize the emission of Er3+ ions which was attributed to the efficient energy transfer from Bi3+ to Er3+ ions and the modification of the local symmetry of Er3+ ions. The results show that the CaSnO3:Er(3+)-Bi3+ nanocrystals have potential application for fabricating visible upconversion devices. PMID:20355589

  4. Preparation and luminescence properties of orange-red Ba3Y(PO4)3:Sm3+ phosphors

    NASA Astrophysics Data System (ADS)

    Xu, Qiguang; Xu, Denghui; Sun, Jiayue

    2015-04-01

    Ba3Y(PO4)3:Sm3+ phosphors were prepared by a high temperature solid-state reaction in air. X-ray diffraction (XRD), photoluminescence spectra and temperature-dependent emission spectra were utilized to characterize the structure and luminescence properties of the as-prepared phosphor. The results show that the phosphor can be efficiently excited by ultraviolet light and emit a satisfactory orange-red performance, nicely, fitting in well with the widely used UV LED chip. Under 403 nm excitation, the 4G5/2 → 6HJ (J = 5/2, 7/2, 9/2, and 11/2) emissions of Sm3+ are obviously observed. The optimum doping concentration is 5 mol% and corresponding quenching behavior is ascribed to be electric dipole-dipole interaction according to Dexter's theory. The temperature dependent luminescence of Ba3Y(PO4)3:Sm3+ phosphor is also discussed, and the activation energy for thermal quenching is calculated as 0.34 eV. Furthermore, the chromaticity coordinates of Ba3Y(PO4)3:Sm3+ phosphor are calculated to be (0.5558, 0.4380) and the lifetime values of Ba3Y0.995(PO4)3:0.005Sm3+ was 2.45 ms.

  5. Redox and luminescent properties of robust and air-stable N-heterocyclic carbene group 4 metal complexes.

    PubMed

    Romain, Charles; Choua, Sylvie; Collin, Jean-Paul; Heinrich, Martine; Bailly, Corinne; Karmazin-Brelot, Lydia; Bellemin-Laponnaz, Stéphane; Dagorne, Samuel

    2014-07-21

    Robust and air-stable homoleptic group 4 complexes of the type M(L)2 [1-3; M = Ti, Zr, Hf; L = dianionic bis(aryloxide) N-heterocyclic carbene (NHC) ligand] were readily synthesized from the NHC proligand 1,3-bis(3,5-di-tert-butyl-2-hydroxyphenyl)imidazolinium chloride (H3L,Cl) and appropriate group 4 precursors. As deduced from cyclic voltammetry studies, the homoleptic bis-adduct zirconium and hafnium complexes 2 and 3 can also be oxidized, with up to four one-electron-oxidation signals for the zirconium derivative 2 (three reversible signals). Electron paramagnetic resonance data for the one-electron oxidation of complexes 1-3 agree with the formation of ligand-centered species. Compounds 2 and 3 are luminescent upon excitation in the absorption band at 362 nm with emissions at 485 and 534 nm with good quantum yields (ϕ = 0.08 and 0.12) for 2 and 3, respectively. In contrast, the titanium complex 1 does not exhibit luminescent properties upon excitation in the absorption band at 310 and 395 nm. Complexes 2 and 3 constitute the first examples of emissive nonmetallocene group 4 metal complexes. PMID:24957272

  6. Synthesis and the luminescent properties of the Nd3+ ions doped three kinds of fluoride nanocrystals in organic solvents

    NASA Astrophysics Data System (ADS)

    Chen, Zhuo; Tian, Changyong; Bo, Shuhui; Liu, Xinhou; Zhen, Zhen

    2015-10-01

    Oleic acid (OA)-modified LaF3:Nd, NaYF4:Nd and CaF2:Nd nanocrystals (NCs) with the different Nd3+ ion concentration (2% and 5%) have been prepared. The structure and morphology of NCs were identified by XRD, TEM, FT-IR and TGA. The size of OA-modified NC is a mean diameter of 5-10 nm and can be dispersed in common organic solvents to form a transparent solution. The optical loss of NCs in organic solvent is the first time to discuss in this work. The luminescence properties of NCs were also characterized and studied by fluorescence spectrometer. The nanoparticles in solid and in the solution all exhibited the strong emission at the 1060 nm when the materials were excited around 800 nm. Compared with the LaF3 and CaF2 matrix, NaYF4 as the host can protect the Nd3+ ions more efficiently away from the nonradiative transitions. The longest luminescent lifetime of the solid NaYF4:2%Nd NCs was up to 136 μs, and the little difference of the fluorescence lifetime existed between the NCs in solid state and in solution. The low optical loss in organic solvent indicated that the Nd3+ ions-doped fluoride NCs are promising materials for optical amplification fields.

  7. SU-E-T-585: Optically-Stimulated Luminescent Dosimeters for Monitoring Pacemaker Dose in Radiation Therapy

    SciTech Connect

    Apicello, L; Riegel, A; Jamshidi, A

    2015-06-15

    Purpose: A sufficient amount of ionizing radiation can cause failure to components of pacemakers. Studies have shown that permanent damage can occur after a dose of 10 Gy and minor damage to functionality occurs at doses as low as 2 Gy. Optically stimulated thermoluminescent dosimeters (OSLDs) can be used as in vivo dosimeters to predict dose to be deposited throughout the treatment. The purpose of this work is to determine the effectiveness of using OSLDs for in vivo dosimetry of pacemaker dose. Methods: As part of a clinical in vivo dosimetry experience, OSLDs were placed at the site of the pacemaker by the therapist for one fraction of the radiation treatment. OSLD measurements were extrapolated to the total dose to be received by the pacemaker during treatment. A total of 79 measurements were collected from November 2011 to December 2013 on six linacs. Sixty-six (66) patients treated in various anatomical sites had the dose of their pacemakers monitored. Results: Of the 79 measurements recorded, 76 measurements (96 %) were below 2 Gy. The mean and standard deviation were 50.12 ± 76.41 cGy. Of the 3 measurements that exceeded 2 Gy, 2 measurements matched the dose predicted in the treatment plan and 1 was repeated after an unexpectedly high Result. The repeated measurement yielded a total dose less than 2 Gy. Conclusion: This analysis suggests OSLDs may be used for in vivo monitoring of pacemaker dose. Further research should be performed to assess the effect of increased backscatter from the pacemaker device.

  8. SU-E-T-315: The Change of Optically Stimulated Luminescent Dosimeters (OSLDs) Sensitivity by Accumulated Dose and High Dose

    SciTech Connect

    Han, S; Jung, H; Kim, M; Ji, Y; Kim, K; Choi, S; Park, S; Yoo, H; Yi, C

    2014-06-01

    Purpose: The objective of this study is to evaluate radiation sensitivity of optical stimulated luminance dosimeters (OSLDs) by accumulated dose and high dose. Methods: This study was carried out in Co-60 unit (Theratron 780, AECL, and Canada) and used InLight MicroStar reader (Landauer, Inc., Glenwood, IL) for reading. We annealed for 30 min using optical annealing system which contained fluorescent lamps (Osram lumilux, 24 W, 280 ∼780 nm). To evaluate change of OSLDs sensitivity by repeated irradiation, the dosimeters were repeatedly irradiated with 1 Gy. And whenever a repeated irradiation, we evaluated OSLDs sensitivity. To evaluate OSLDs sensitivity after accumulated dose with 5 Gy, We irradiated dose accumulatively (from 1 Gy to 5 Gy) without annealing. And OSLDs was also irradiated with 15, 20, 30 Gy to certify change of OSLDs sensitivity after high dose irradiation. After annealing them, they were irradiated with 1Gy, repeatedly. Results: The OSLDs sensitivity increased up to 3% during irradiating seven times and decreased continuously above 8 times. That dropped by about 0.35 Gy per an irradiation. Finally, after 30 times irradiation, OSLDs sensitivity decreased by about 7%. For accumulated dose from 1 Gy to 5 Gy, OSLDs sensitivity about 1 Gy increased until 4.4% after second times accumulated dose compared with before that. OSLDs sensitivity about 1 Gy decreased by 1.6% in five times irradiation. When OSLDs were irradiated ten times with 1Gy after irradiating high dose (10, 15, 20 Gy), OSLDs sensitivity decreased until 6%, 9%, 12% compared with it before high dose irradiation, respectively. Conclusion: This study certified OSLDs sensitivity by accumulated dose and high dose. When irradiated with 1Gy, repeatedly, OSLDs sensitivity decreased linearly and the reduction rate of OSLDs sensitivity after high dose irradiation had dependence on irradiated dose.

  9. Monodisperse spherical mesoporous Eu-doped TiO2 phosphor particles and the luminescence properties

    NASA Astrophysics Data System (ADS)

    Yin, Jianbo; Xiang, Liqin; Zhao, Xiaopeng

    2007-03-01

    Monodisperse spherical and mesoporous Eu-doped TiO2 phosphor particles were prepared by nonionic surfactant-assisted soft-chemistry method. It is shown that the phosphor particles possess submicron diameter of about 250nm and narrow size distribution. Under ultraviolet irradiation the particles show characteristic luminescence corresponding to D05-Fj7 of Eu3+. Especially, the calcined particles consisted of mesopores and semicrystalline framework shows the strongest photoluminescence compared to the amorphous particles without annealing and the completely crystalline particles annealed at higher temperature. This is attributed to the energy transfer from titania nanocrystallite to Eu3+ ions dispersed in glassy amorphous titania region.

  10. Preparation and luminescent properties of GdOF:Ce, Tb nanoparticles and their transparent PMMA nanocomposites

    NASA Astrophysics Data System (ADS)

    Cai, Wen; Wang, Aiwu; Fu, Li; Hu, Jie; Rao, Tingke; Wang, Junqing; Zhong, Jiasong; Xiang, Weidong

    2015-05-01

    GdOF:Ce, Tb nanoparticles and their poly (methyl methacrylate) (PMMA) nanocomposites have been successfully prepared by a thermolysis route and thermal polymerization of methyl methacrylate (MMA) monomer, respectively. The obtained nanoparticles and nanocomposites are characterized by XRD, EDS, TEM, FTIR, TGA, UV-Vis and PL spectrum. The as-synthesized transparent GdOF:Ce, Tb/PMMA nanocomposites exhibit green photoluminescence under the irradiation of 254 nm UV lamp due to the incorporation of luminescent GdOF:Ce, Tb nanoparticles into the PMMA matrix. The present route would provide a general strategy to prepare other functional nanocomposites.

  11. Luminescence Properties of Eu2+-Doped Red-Emitting Sr-Containing Sialon Phosphor

    NASA Astrophysics Data System (ADS)

    Fukuda, Yumi; Okada, Aoi; Keiko Albessard, Ariane

    2012-06-01

    We developed a Eu2+-doped red-emitting Sr-containing sialon phosphor Sr2Si7Al3ON13:Eu2+ that could play a very important role in high color rendering of white light-emitting diodes (LEDs) for solid-state lighting. It realizes both high efficiency and small thermal quenching under excitation by blue light, which are essential for operation in a high-temperature atmosphere. It shows a highly efficient red luminescence whose external quantum efficiency reaches 73% for 450 nm excitation. These features show that this red-emitting phosphor has high potential for application to white LEDs.

  12. Measurements of Thermally Stimulated Luminescence in Gamma-Irradiated Ultra-High Molecular Weight Polyethylene in the Presence of Vitamin E

    NASA Astrophysics Data System (ADS)

    Abdi, Dereje; Jahan, Muhammed; Walters, Benjamin

    2011-03-01

    Thermally stimulated luminescence (TSL) was detected in medical grade ultra-high molecular weight polyethylene (UHMWPE) GUR 1020 (Ticona) after gamma irradiation at room temperature (22circ; C) in air or nitrogen and subsequent heating from 22circ; C to 399circ; C using a commercial TSL apparatus (Thermec). A typical TSL glow curve exhibits two major glow peaks near 116circ; C and 200circ; C with a weak shoulder near 250circ; C. Additional glow peak is observed near 140circ; C in GUR 1020E (UHMWPE containing 0.1% vitamin E (alpha-tocopherol (α -T)). Full-width-at-half-max (FWHM) and activation energy for each peak were found as follows. 116circ; C: 40circ; C, 1.2 eV; 140circ; C: 40circ; C, 1.3 eV; 200circ; C: 64circ; C, 1.0 eV; 250circ; C: 56circ; C, 1.5 eV. The glow peaks seem to follow a kinetic order of 1.5. While the 116&-circ; C glow is produced in all irradiated samples, the 200circ; - and 250&-circ; C peaks are produced when irradiation is performed in air, suggesting that these latter glow peaks are associated with the oxygen-centered species and the former (at 116circ; C) with polyethylene (PE) radicals. The 140&-circ; C peak could result from thermal breakdown of vitamin E radical (α -T-O*). Irradiation dose, 30, 65 or 100 kGy, simply changes the TSL intensity without affecting the TSL characteristic. Vitamin E, which is used as an antioxidant, does not seem to affect the TSL in UHMWPE. NSF Center for Biosurfaces and the University of Memphis.

  13. Optically Stimulated Luminescence Response to Ionizing Radiation of Red Bricks (SiO2, Al2O3, and Fe2O3) Used as Building Materials

    SciTech Connect

    Bogard, James S; Espinosa Garcia, Guillermo

    2007-01-01

    Quartz is the most common mineral in our environment. It is found in granite, hydrothermal veins and volcanic rocks, as well as in sedimentary deposits derived from such solid materials. These sediments are also made into building materials, such as bricks and pottery. Thus the potential use of a dose reconstruction technique based on quartz grains is enormous, whether as a dating tool in archaeology and quaternary geology, or in nuclear accident dosimetry. This work describes the Optically Stimulated Luminescence (OSL) response of red brick to ionizing radiation. The bricks, from the state of Puebla, Mexico, represent another class of materials that can be used in retrospective dosimetry following nuclear or radiological incidents. The chemical composition of fifteen bricks (three samples from five different brick factories) was determined, using energy dispersive spectroscopy (EDS), be primarily SiO{sub 2}, Al{sub 2}O{sub 3} and Fe{sub 2}O{sub 3} and is believed to be representative for this common building material. Individual aliquots from these bricks were powdered in agate mortars and thermally annealed. Replicate samples of the aliquots were then irradiated with beta particles from a sealed source of {sup 90}Sr/{sup 90}Y. The OSL response was measured with a Daybreak Model 2200 High-Capacity OSL Reader System. We present here for this material the characteristic OSL response to beta particles; the reproducibility of the OSL response; the linearity of the response in the dose range 0.47 Gy to 47 Gy; and the fading characteristics.

  14. The age of three Middle Palaeolithic sites: Single-grain optically stimulated luminescence chronologies for Pech de l'Azé I, II and IV in France.

    PubMed

    Jacobs, Zenobia; Jankowski, Nathan R; Dibble, Harold L; Goldberg, Paul; McPherron, Shannon J P; Sandgathe, Dennis; Soressi, Marie

    2016-06-01

    Optically stimulated luminescence (OSL) measurements were made on individual, sand-sized grains of quartz from Middle Palaeolithic deposits at three sites (Pech de l'Azé I, II and IV) located close to one another in the Dordogne region of southwest France. We were able to calculate OSL ages for 69 samples collected from these three sites. These ages reveal periods of occupation between about 180 and 50 thousand years ago. Our single-grain OSL chronologies largely support previous age estimates obtained by thermoluminescence dating of burnt flints at Pech IV, electron spin resonance dating of tooth enamel at Pech I, II and IV and radiocarbon dating of bone at Pech I and IV, but provide a more complete picture due to the ubiquitous presence of sand-sized quartz grains used in OSL dating. These complete chronologies for the three sites have allowed us to compare the single-grain ages for similar lithic assemblages among the three sites, to test the correlations among them previously proposed by Bordes in the 1970s, and to construct our own correlative chronological framework for the three sites. This shows that similar lithic assemblages occur at around the same time, and that where a lithic assemblage is unique to one or found at two of the Pech sites, there are no deposits of chronologically equivalent age at the other Pech site(s). We interpret this to mean that, at least for these Pech de l'Azé sites, the Mousterian variants show temporal ordering. Whether or not this conclusion applies to the wider region and beyond, the hypothesis that Mousterian industrial variation is temporally ordered cannot be refuted at this time. PMID:27260176

  15. Energy dependence measurement of small-type optically stimulated luminescence (OSL) dosimeter by means of characteristic X-rays induced with general diagnostic X-ray equipment.

    PubMed

    Takegami, Kazuki; Hayashi, Hiroaki; Okino, Hiroki; Kimoto, Natsumi; Maehata, Itsumi; Kanazawa, Yuki; Okazaki, Tohru; Hashizume, Takuya; Kobayashi, Ikuo

    2016-01-01

    For X-ray inspections by way of general X-ray equipment, it is important to measure an entrance-skin dose. Recently, a small optically stimulated luminescence (OSL) dosimeter was made commercially available by Landauer, Inc. The dosimeter does not interfere with the medical images; therefore, it is expected to be a convenient detector for measuring personal exposure doses. In an actual clinical situation, it is assumed that X-rays of different energies will be detected by a dosimeter. For evaluation of the exposure dose measured by a dosimeter, it is necessary to know the energy dependence of the dosimeter. Our aim in this study was to measure the energy dependence of the OSL dosimeter experimentally in the diagnostic X-ray region. Metal samples weighing several grams were irradiated and, in this way, characteristic X-rays having energies ranging from 8 to 85 keV were generated. Using these mono-energetic X-rays, the dosimeter was irradiated. Simultaneously, the fluence of the X-rays was determined with a CdTe detector. The energy-dependent efficiency of the dosimeter was derived from the measured value of the dosimeter and the fluence. Moreover, the energy-dependent efficiency was calculated by Monte-Carlo simulation. The efficiency obtained in the experiment was in good agreement with that of the simulation. In conclusion, our proposed method, in which characteristic X-rays are used, is valuable for measurement of the energy dependence of a small OSL dosimeter in the diagnostic X-ray region. PMID:26589210

  16. Thermal annealing effects on ultra-violet luminescence properties of Gd doped AlN

    SciTech Connect

    Kita, Takashi; Ishizu, Yuta; Tsuji, Kazuma; Harada, Yukihiro; Chigi, Yoshitaka; Nishimoto, Tetsuro; Tanaka, Hiroyuki; Kobayashi, Mikihiro; Ishihara, Tsuguo; Izumi, Hirokazu

    2015-04-28

    We studied energy transfer from AlN to doped Gd{sup 3+} ions as a function of the post-thermal annealing temperature. Gd-doped AlN thin films were deposited on fused-silica substrates using a reactive radio-frequency magnetron sputtering technique. The film is a c-axis oriented polycrystal. The intra-orbital electron transition in Gd{sup 3+} showed an atomically sharp luminescence at 3.9 eV (318 nm). The photoluminescence (PL) excitation spectrum exhibited a resonant peak, indicating efficient energy transfer from the host AlN crystal to Gd{sup 3+} ions. The PL intensity increases approximately ten times by thermal annealing. The PL decay lifetime becomes long with annealing, and mid-gap luminescence relating to the crystal defects in AlN was also found to be reduced by annealing. These results suggest that energy dissipation of excited carriers in AlN was suppressed by annealing, and the efficiency of energy transfer into Gd{sup 3+} was improved.

  17. Preparation and luminescence properties of ZnO:Ga - polystyrene composite scintillator.

    PubMed

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

    2016-07-11

    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-exponential decay with the decay time around 500 ps. PMID:27410805

  18. Luminescence properties of [Ru(bpy) 2MDHIP] 2+ modulated by the introduction of DNA, copper(II) ion and EDTA

    NASA Astrophysics Data System (ADS)

    Chen, Miaojing; Li, Hong; Li, Qian; Xu, Zhenghe

    2010-05-01

    The luminescence properties of [Ru(bpy) 2MDHIP] 2+ (bpy = 2,2'-bipyridine, MDHIP = 2,4-dihydrophenyl-imidazo[4,5-f][1,10]phenanthroline) in the absence and presence of DNA modulated by the introduction of Cu 2+ ion and EDTA have been investigated. It is found that the ruthenium(II) complex can insert and stack between the base pairs of calf thymus DNA with MDHIP ligand, and the intramolecular hydrogen bond is located inside of the DNA. The presence of DNA can enhance the luminescence intensities of [Ru(bpy) 2MDHIP] 2+ both in buffer solution and on an ITO surface. Moreover, the luminescence intensities of [Ru(bpy) 2MDHIP] 2+ and DNA-bound [Ru(bpy) 2MDHIP] 2+ are quenched by Cu 2+, and next recovered by the addition of EDTA. The repetitive luminescence-modulations have been achieved through the introduction of equimolar Cu 2+ and EDTA, respectively. In addition, it becomes evident that the number of luminescence-modulation cycles for [Ru(bpy) 2MDHIP] 2+ in the absence and presence of DNA is influenced by the cumulative concentrations of CuEDTA, generated successively by the strong coordination of Cu 2+ to EDTA.

  19. Temperature lags of luminescence measurements in a commercial luminescence reader

    NASA Astrophysics Data System (ADS)

    Kitis, George; Kiyak, Nafiye G.; Polymeris, George S.

    2015-09-01

    The temperature recorded in thermoluminescence and optically stimulated luminescence equipments is not the temperature of the sample but that of the heating element on which the thermocouple is attached. Depending upon the rate of heating, a temperature difference appears between the samples and the heating element, termed as temperature lag, which could have serious effects on the curve shapes and trapping parameters. In the present work the temperature lag effect is studied in a newly developed luminescence equipment measuring both thermoluminescence and optically stimulated luminescence. It is found that the temperature lag could be large for heating rates above 2 K/s and it is strongly dependent upon the sample holder. A simple approximation method is proposed in order to both predict as well as correct for temperature lag effects in luminescence measurements.

  20. Influence of chromium interaction with native and impurity defects on optical and luminescence properties of ZnSe:Cr crystals

    NASA Astrophysics Data System (ADS)

    Radevici, I.; Sushkevich, K.; Colibaba, G.; Sirkeli, V.; Huhtinen, H.; Nedeoglo, N.; Nedeoglo, D.; Paturi, P.

    2013-11-01

    Luminescent properties of the chromium doped zinc selenide crystals with various concentrations of the doping impurity in 0.03-0.30 at. % range within the temperature interval from 6 K to 300 K were studied. Chromium doping was performed in various technological processes: during the growth by chemical vapor transport method; during the growth from melt; by thermal diffusion from the Bi + Cr melt or by thermal diffusion from gas. Possibility of chromium-bound excitons formation was shown, as well as chromium impurity participation in formation of emission bands in IR spectral region. A mechanism of chromium doping impurity interaction with uncontrolled background impurities and zinc selenide structural defects was proposed based on experimental data. An assumption about resonant energy transfer between double charged chromium ions and complexes based on crystals vacancy defects was made.

  1. Easily Accessible Rare-Earth-Containing Phosphonium Room-Temperature Ionic Liquids: EXAFS, Luminescence, and Magnetic Properties.

    PubMed

    Alvarez-Vicente, Jorge; Dandil, Sahra; Banerjee, Dipanjan; Gunaratne, H Q Nimal; Gray, Suzanne; Felton, Solveig; Srinivasan, Geetha; Kaczmarek, Anna M; Van Deun, Rik; Nockemann, Peter

    2016-06-16

    A range of liquid rare earth chlorometallate complexes with the alkyl-phosphonium cation, [P666 14](+), has been synthesized and characterized. EXAFS confirmed the predominant liquid-state speciation of the [LnCl6](3-) ion in the series with Ln = Nd, Eu, Dy. The crystal structure of the shorter-alkyl-chain cation analogue [P4444](+) has been determined and exhibits a very large unit cell. The luminescence properties, with visible-light emissions of the liquid Tb, Eu, Pr, and Sm and the NIR emissions for the Nd and Er compounds, were determined. The effective magnetic moments were measured and fitted for the Nd, Tb, Ho, Dy, Gd, and Er samples. PMID:27203286

  2. Luminescence properties of Tb3+ doped Sr2SnO4 green phosphor in UV/VUV regions.

    PubMed

    Srinivas, M; Rao, B Appa; Vithal, M; Rao, P Raghava

    2013-01-01

    Polycrystalline Sr2SnO4 phosphors doped with Tb(3+) were prepared by conventional solid-state reaction method. Materials were characterized by powder XRD and EDS techniques. The luminescence properties of these materials were investigated under UV and VUV excitation. Upon excitation at 272 nm, phosphors exhibited intense emissions at 492 and 543 nm due to (5)D4 → (7)F6 and (5)D4 → (7)F5 transitions of Tb(3+) ions, respectively. Materials also exhibited strong emissions from these transitions under VUV excitation at 147, 173 and 230 nm. Quantitative analysis of the spectra indicated probable applications of these phosphors for PDP and other display devices as green emitting phosphors. PMID:22733625

  3. Synthesis and spectral luminescent properties of certain pyridine and quinoline analogs of isomeric distyrylnaphthalenes and styryl- and distrylanthracenes

    SciTech Connect

    Vernigor, E.M.; Koz'menko, M.V; Lebedev, S.A.; Luk'yanets, E.A.; Savvina, L.P.; Shalaev, V.K.

    1987-12-01

    A series of pyridine and quinoline analogs of isomeric distyrylnaphthalenes and styryl- and distyrylanthracenes has been synthesized. Their spectral-luminescent properties were studied. Compounds whose structures are sterically hindered in the ground state have the highest Stokes' shift. The compounds synthesized have a trans-configuration; in their IR spectra there are absorption bands in the 970-990 cm/sup -1/ region, characteristic for trans-disubstituted alkenes. In the PMR spectrum of 9,10-di(..beta..-(4-pyridyl)vinyl)anthracene, two doublets of the AB spin system are observed with chemical shifts of 6.91 and 7.37 ppm, belonging to the vinyl protons. The SSCC (J = 16.5 Hz) indicates a trans-configuration of this compound.

  4. Synthesis of Ba2SiO4:Eu(2+) by a Hybrid Process and Its Luminescent Properties.

    PubMed

    Park, Jung Hye; Ahn, Wonsik; Kim, Young Jin

    2015-10-01

    Ba2SiO4:Eu(2+) powders were prepared using a sol-gel-combustion (hybrid) process with tetraethyl orthosilicate (TEOS) and colloidal silica (C-SiO2) as Si sources. The effects of the silicon sources and preparation conditions on phase formation and luminescent properties were investigated. The B2S:Eu(2+) powders synthesized with TEOS were composed of the irregular particles, whereas C-SiO2 was more conducive to uniform particle distribution for the Ba2SiO4:Eu(2+) powders, leading to the enhancement of the emission intensity. The photoluminescence spectra of the synthesized powders exhibited broad excitation bands spanning 250 to 450 nm, and strong green-emission bands, whose intensities and positions were heavily dependent on the concentration of Eu(2+) and Sr(2+) substituted for Ba(2+) in Ba2SiO4. PMID:26726479

  5. Down-conversion luminescence and its temperature-sensing properties from Er3+-doped sodium bismuth titanate ferroelectric thin films

    NASA Astrophysics Data System (ADS)

    Wang, Shanshan; Zheng, Shanshan; Zhou, Hong; Pan, Anlian; Wu, Guangheng; Liu, Jun-ming

    2015-11-01

    Here, we demonstrate outstanding temperature-sensing properties from Na0.5Bi0.49Er0.01TiO3 (NBT:Er) thin films. The perovskite phase for them is stable in the temperature range from 80 to 440 K. Interestingly, the Er doping enhances the ferroelectric polarization and introduces local dipolar, which are positive for temperature sensing. Pumped by a 488-nm laser, the NBT:Er thin films show strong green luminescence with two bands around 525 and 548 nm. The intensity ratio I 525/ I 548 can be used for temperature sensing, and the maximum sensitivity is about 2.3 × 10-3 K-1, higher than that from Er-doped silicon oxide. These suggest NBT:Er thin film is a promising candidate for temperature sensor.

  6. Luminescence properties and energy transfer in Eu2+, Mn2+ codoped Na(Sr,Ba)PO4 phosphor

    NASA Astrophysics Data System (ADS)

    Zhang, Qiuhong; Ni, Haiyong; Wang, Lingli

    2014-03-01

    Eu2+ and Mn2+ singly doped and codoped Na(Sr,Ba)PO4 phosphors were synthesized, and their luminescent properties were investigated. A broad blue emission and a broad orange emission band were observed in Na(Sr,Ba)PO4:Eu2+, Mn2+ phosphor. The resonant-type energy transfer from Eu2+ to Mn2+ was demonstrated, and the energy transfer efficiency was also calculated according to their emission spectra. Based on the principle of energy transfer, the emission intensity ration of Eu2+ and Mn2+ could be appropriately tuned by adjusting the contents of activators. Due to the strong absorption in the 250-400 nm range, Na(Sr,Ba)PO4:Eu2+, Mn2+ phosphor could be used as a potential candidate for near-UV white light-emitting diodes (LEDs).

  7. Study of a Strong Luminescent Core Shell Nanocomposite of Europium Complex Coated on Gold Nanoparticles: Synthesis and Properties

    NASA Astrophysics Data System (ADS)

    Khuyen, Hoang Thi; Huong, Tran Thu; Tung, Do Khanh; Thu, Phung Thi; Binh, Nguyen Thanh; Minh, Le Quoc; Anh, Tran Kim; Diep, Lai Ngoc; Lien, Nghiem Thi Ha; Tuan, Pham Anh

    2016-08-01

    The large Stokes shifts and long lifetimes observed for lanthanide complexes are especially important for bioimaging. To incorporate the benefits of lanthanide lumophores into nanoscale probes, size-tunable gold nanoparticles (GNPs) coated with luminescent europium(III) complexes were synthesized using a modified Stober method with in situ doping of europium(III) complexes with tri- n-octylphosphineoxide (TOPO) and naphthoyl trifluoroacetone (NTA) ligands. The results show that the integration of europium(III) complexes with GNPs significantly extends their absorption band towards the visible region. Emission spectrum of these GNPs coated with europium(III) complexes shows the characteristic 5D0 → 7F n ( n = 1, 2, 3, 4) transitions of an Eu(III) ion. Their fluorescence lifetime of 460 μs was observed. The effect of different sizes of GNPs on their photophysical properties was also investigated.

  8. Study of a Strong Luminescent Core Shell Nanocomposite of Europium Complex Coated on Gold Nanoparticles: Synthesis and Properties

    NASA Astrophysics Data System (ADS)

    Khuyen, Hoang Thi; Huong, Tran Thu; Tung, Do Khanh; Thu, Phung Thi; Binh, Nguyen Thanh; Minh, Le Quoc; Anh, Tran Kim; Diep, Lai Ngoc; Lien, Nghiem Thi Ha; Tuan, Pham Anh

    2016-05-01

    The large Stokes shifts and long lifetimes observed for lanthanide complexes are especially important for bioimaging. To incorporate the benefits of lanthanide lumophores into nanoscale probes, size-tunable gold nanoparticles (GNPs) coated with luminescent europium(III) complexes were synthesized using a modified Stober method with in situ doping of europium(III) complexes with tri-n-octylphosphineoxide (TOPO) and naphthoyl trifluoroacetone (NTA) ligands. The results show that the integration of europium(III) complexes with GNPs significantly extends their absorption band towards the visible region. Emission spectrum of these GNPs coated with europium(III) complexes shows the characteristic 5D0 → 7F n (n = 1, 2, 3, 4) transitions of an Eu(III) ion. Their fluorescence lifetime of 460 μs was observed. The effect of different sizes of GNPs on their photophysical properties was also investigated.

  9. Study of the structure and luminescent properties of terbium complex intercalated Zn/Al layered double hydroxide

    NASA Astrophysics Data System (ADS)

    Gao, Xiaorui; Xie, Juan; Yin, Yaobing; Hao, Yongjing; Lian, Yiwei

    2016-01-01

    Terbium complex of ethylenediaminetetraacetate ([Tb(EDTA)]-) intercalated Zn/Al layered double hydroxide (LDH), as an inorganic-organic green-emitting phosphor, was synthesized through an ion exchange method. X-ray powder diffraction (XRD) and Fourier transform infrared (FTIR) spectra exhibit a successful intercalation of [Tb(EDTA)]- anions between the hydroxide sheets of the LDH. The basal spacing of 14.5 Å indicate a vertical arrangement of [Tb(EDTA)]- anions with the maximal dimension in the gallery is adopted. The luminescent properties of this material were studied by excitation and emission spectra. The results show that the strongest emission peak of Tb3+ ion occurs at 544 nm. This material may supply a candidate of green light emitting phosphor.

  10. Photoinduced energy transfer across non-covalent bonds in the nanoscale: cyclodextrin hosts with enhanced luminescent properties for guest communication.

    PubMed

    Faiz, Jonathan A; Kyllonen, Lasse E P; Contreras-Carballada, Pablo; Williams, René M; De Cola, Luisa; Pikramenou, Zoe

    2009-05-28

    Two photoactive cyclodextrin hosts have been prepared and studied in participation on photophysical processes, one with a ruthenium tris(bipyridyl) core which forms a trimeric host and the other with an appended anthracene unit. An acetylide functionalized bipyridyl cyclodextrin, , was prepared by palladium coupling of mono-6-propargyl permethylated beta-CD and 4-bromo-2,2'-bipyridine. The ruthenium complex, [Ru(3)]Cl(2), shows luminescence from the (3)MLCT centered at 650 nm with a quantum yield of 0.044 and a lifetime at room temperature of 1.1 micros in aerated aqueous solution. The enhanced luminescence properties have been attributed to extra delocalisation afforded by the three propargyl units appended to the complex and the stabilization of the MLCT state. An anthracene functionalised cyclodextrin was prepared from mono-6-O-p-toluenesulfonyl permethylated beta-cyclodextrin and 9-anthracene methanol. It shows fluorescence at room temperature with a maximum at 400 nm with a lifetime of 7 ns. Transient absorption spectroscopy has been used to elucidate the excited state properties of [Ru(3)]Cl(2) and hosts. A broad band centered around 600 nm in the [Ru(3)]Cl(2) transient spectrum corresponds to the absorption of the pi-radical anion of the ethynyl fragment of ligand and in a signal at 595 nm was observed, corresponding to the absorption of the anthracene excited singlet state. We used a bisadamantyl guest to assemble the two hosts and studied the energy transfer from the ruthenium core to the anthracene unit by steady state emission spectroscopy. The photoinduced energy transfer process in assemblies of host with ruthenium or osmium metalloguests, [Ru(biptpy)(tpy)](NO(3))(2) and [Os(biptpy)(tpy)](NO(3))(2), was studied by femtosecond transient spectroscopy and steady state emission spectroscopy. The singlet state of the anthracene pendant unit acted as a donor to the MLCT of the Ru(II) or Os(II) metalloguests. An energy transfer rate from the singlet

  11. Thermally Stimulated Luminescence of hbox {Y}2{Si}{O}5{:} {Ce}^{3+} Commercial Phosphor Powder and Thin Films

    NASA Astrophysics Data System (ADS)

    Debelo, N. G.; Dejene, F. B.; Roro, Kittessa

    2016-07-01

    We report on the thermoluminescence (TL) properties of hbox {Y}2{Si}{O}5{:} {Ce}^{3+} phosphor powder and thin films. For the phosphor powder, the TL intensity increases with an increase in UV dose for up to 20 min and then decreases. The TL intensity peak shifts slightly to higher-temperature region at relatively high heating rates, but with reduced peak intensity. Important TL kinetic parameters, such as the activation energy ( E) and the frequency factor ( s), were calculated from the glow curves using a variable heating rate method, and it was found that the glow peaks obey first-order kinetics. For the films, broad TL emissions over a wide temperature range with reduced intensity relative to that of the powder were observed. The maxima of the TL glow peaks of the films deposited in oxygen ambient and vacuum shift toward higher temperature relative to the TL peak position of the film deposited in an argon environment. Vacuum environment resulted in the formation of a deep trap relative to oxygen and argon environments. Furthermore, the structure of hbox {Y}2{Si}{O}5{:} {Ce}^{3+} phosphor powder transformed from {x}2-monoclinic polycrystalline phase to {x}1-monoclinic polycrystalline phase, for deposition at low substrate temperature.

  12. Influence of technological conditions upon the luminescence properties of ZnTe-ZnSe heterostructures grown by liquid-phase epitaxy

    SciTech Connect

    Skobeeva, V.M.; Semenyuk, L.N.; Serdyuk V.V.

    1986-08-01

    This paper studies the luminescence characteristics of the components of ZnTe-ZnSe hetero-structures obtained by liquid-phase epitaxy of ZnTe and SnSe substrates oriented in the (III) plane; the epitaxy was based on a solution-melt in metal (Sn, Bi). The influence of the metal melt and the technological conditions of crystal growing upon the luminescence properties of the ZnSe substrate is studied. The authors followed the changes in the ZnSe luminescence spectrum in each stage of the study. Typical photoluminescence spectra is shown of ZnSe single crystals which had been grown recently and annealed in liquid Zn. When ZnTe-ZnSe heterostructures are produced by liquid phase epitaxy from solution melts in Bi and Sn, the radiative properties of ZnSe substrates do not change because disturbances of stoichiometry are prevented. The luminescence properties of ZnSe substrates which were subjected to annealing can be described by the concepts of annealing ZnSe with copper.

  13. Dual modal in vivo imaging using upconversion luminescence and enhanced computed tomography properties

    NASA Astrophysics Data System (ADS)

    Zhang, Guo; Liu, Yanlan; Yuan, Qinghai; Zong, Chenghua; Liu, Jianhua; Lu, Lehui

    2011-10-01

    In vivo upconversion luminescence (UCL) imaging, exhibiting favorable characteristics such as high photostability, no blinking, sharp emission lines, and long lifetimes, is recognized as the excellent and significant photoluminescence imaging for the future. To develop the imaging system with high visual sensitivity and tissue penetration, the functional molecules with X-ray computed tomography (CT) contrast were grafted onto upconversion nanoparticles to obtain β-NaYF4:18% Yb3+,2%Er3+@SiO2-I/PEG (UCNPs@SiO2-I/PEG) nanoprobes. These nanoprobes are water-soluble, have low cytotoxicity, and possess excellent UCL and remarkable CT contrast. Of particular note is that, besides the element iodine, rare earth elements (Y, Yb, and Er) present in the nanoprobes also show CT contrast. Moreover, no background autofluorescence signal is found in in vivo UCL images. We believe that these nanoprobes with dual modal in vivo imaging of UCL and CT can serve as a promising platform for clinical diagnosis or biomedical studies.In vivo upconversion luminescence (UCL) imaging, exhibiting favorable characteristics such as high photostability, no blinking, sharp emission lines, and long lifetimes, is recognized as the excellent and significant photoluminescence imaging for the future. To develop the imaging system with high visual sensitivity and tissue penetration, the functional molecules with X-ray computed tomography (CT) contrast were grafted onto upconversion nanoparticles to obtain β-NaYF4:18% Yb3+,2%Er3+@SiO2-I/PEG (UCNPs@SiO2-I/PEG) nanoprobes. These nanoprobes are water-soluble, have low cytotoxicity, and possess excellent UCL and remarkable CT contrast. Of particular note is that, besides the element iodine, rare earth elements (Y, Yb, and Er) present in the nanoprobes also show CT contrast. Moreover, no background autofluorescence signal is found in in vivo UCL images. We believe that these nanoprobes with dual modal in vivo imaging of UCL and CT can serve as a promising

  14. Temperature-dependent luminescent properties of Eu-Tb complexes synthesized in situ in gel glass

    NASA Astrophysics Data System (ADS)

    Liu, Yan; Qian, Guodong; Wang, Zhiyu; Wang, Minquan

    2005-02-01

    The chelates of europium and terbium with hexafluoroacetylacetone (HFA) and triphenylphoshine oxide (TPPO), Eu /Tb(HFA)3(TPPO)2, have been synthesized in situ in gel glasses with various concentrations of Eu3+ and Tb3+ ions. The photoluminescence spectra have been measured and the characteristic transitions of Tb3+ and Eu3+ have been observed. Due to the variance of energy transfer efficiencies from Tb3+ to Eu3+, the intensity ratios of europium luminescent band to terbium band vary remarkably with measurement temperatures. In addition, the Förster mechanism has been proved to be responsible for the energy transfer between Eu3+ and Tb3+. The materials doped with Eu /Tb(HFA)3(TPPO)2 are promising for being used as a temperature detector and thermal-sensitive probe of optical fiber sensor.

  15. Tuning of the sensing properties of luminescent Eu(3+) complexes towards the nitrate anion.

    PubMed

    Piccinelli, Fabio; Leonzio, Marco; Bettinelli, Marco; Monari, Magda; Grazioli, Cristian; Melchior, Andrea; Tolazzi, Marilena

    2016-02-28

    A new family of imine-based ligands containing pyridine or furan as an aromatic donating ring [N,N'-bis(2-pyridylmethylidene)-1,2-(R,R + S,S)-cyclohexanediamine, L1; N,N'-bis(2-furanylmethylidene)-1,2-(R,R + S,S)-cyclohexanediamine, L2 and N,N'-bis(2-thienylmethylidene)-1,2-(R,S)-cyclohexanediamine, L3] has been prepared in high yield by means of an easy synthetic protocol. Their trifluoromethansulphonate (CF3SO3(-), OTf(-)) Eu(iii) complexes have been employed for luminescence sensing of the NO3(-) anion in an anhydrous acetonitrile solution. Spectrophotometric titrations have been carried out to define the speciation in the solution and study the formation of ternary species occurring with the addition of NO3(-) anions. The sensing response towards this anion is strongly dependent on the nature of the ligand, the stoichiometry of the complexes and their concentration. PMID:26782359

  16. Luminescence and electrical properties of single ZnO/MgO core/shell nanowires

    SciTech Connect

    Grinblat, Gustavo; Comedi, David; Bern, Francis; Barzola-Quiquia, José; Esquinazi, Pablo; Tirado, Mónica

    2014-03-10

    To neutralise the influence of the surface of ZnO nanowires for photonics and optoelectronic applications, we have covered them with insulating MgO film and individually contacted them for electrical characterisation. We show that such a metal-insulator-semiconductor-type nanodevice exhibits a high diode ideality factor of 3.4 below 1 V. MgO shell passivates ZnO surface states and provides confining barriers to electrons and holes within the ZnO core, favouring excitonic ultraviolet radiative recombination, while suppressing defect-related luminescence in the visible and improving electrical conductivity. The results indicate the potential use of ZnO/MgO nanowires as a convenient building block for nano-optoelectronic devices.

  17. Aggregation of dye molecules and its influence on the spectral luminescent properties of solutions

    NASA Astrophysics Data System (ADS)

    Yuzhakov, V. I.

    1992-06-01

    The principal results of studies carried out in recent years on the molecular aggregation of organic dyes and pigments in solutions are examined and surveyed in the present review. Attention is concentrated on the influence of association on the photoenergetics of the dye molecules. Theoretical studies on the spectral-luminescent spectroscopic characteristics of the molecular aggregates are briefly considered. Studies on the anisotropy of the absorption and on the emission from the associated species are described. Investigations of the concentration depolarisation and concentration quenching of the fluorescence of dye solutions are subjected to a critical analysis. The results of studies of the mixed association of dye molecules and of its influence on the lasing characteristics of the solutions are presented. The physicochemical conditions affecting the efficiency of the association process are examined. The bibliography includes 251 references.

  18. Luminescence properties and optical dephasing in a glass-ceramic containing sodium-niobate nanocrystals

    NASA Astrophysics Data System (ADS)

    Almeida, E.; de S. Menezes, L.; de Araújo, Cid B.; Lipovskii, A. A.

    2011-06-01

    Photoluminescence (PL) and degenerate four-wave-mixing (DFWM) experiments were performed in a silica-niobic composite containing NaNbO3 nanocrystals. The PL results indicate the presence of in-gap states attributed to excitons in the nanocrystals and defect centers. The luminescence of the samples becomes more intense at low temperatures, indicating that nonradiative relaxations dominate the dynamics of the in-gap states. The DFWM experiments allowed for measurements of the homogeneous relaxation time, (20 ± 3) fs, of the third-order polarization at room temperature. The main contributions to the dynamics of the electronic response are attributed to the trapping of electrons in the in-gap states and to carrier and phonon scattering.

  19. Porous heterometallic Cd(II)-Ca(II)-terephthalate: Synthesis, structure, luminescent and gas adsorption properties

    NASA Astrophysics Data System (ADS)

    Liu, Haiping; Dong, Yanli; Ren, Hailiang

    2016-03-01

    A new heterometallic poly(dihydrate-one and a half terephthalate-cadmium calcium) coordination polymer, namely [CdCa(pdc)1.5(H2O)2]n (1, H2pdc = terephthalic acid), has been successfully obtained by the solvothermal reactions of H2pdc, Cd(NO3)2·4H2O and Ca(NO3)2·4H2O. Single crystal X-ray diffraction analysis reveals that compound 1 features a 3D porous framework based on 1D chain subunits. Moreover, compound 1 is luminescent and exhibits high adsorption capacities for H2, CH4 and CO2 at room temperature.

  20. Optical fiber spectroscopy: A study of the luminescent properties of the europium ion for thermal sensors

    NASA Technical Reports Server (NTRS)

    Buoncristiani, A. Martin

    1992-01-01

    Recently, there has been interest in developing a distributed temperature sensor integrated into an optical fiber. Such a system would allow embedding of the optical fiber within or on a structural material to provide for continuous monitoring of the material's temperature. Work has already begun on the development of a temperature sensor using the temperature dependent emission spectra from the lanthanide rare earths doped into crystalline hosts. The lifetime, the linewidth and the integrated intensity of this emission are each sensitive to changes in the temperature and can provide a basis for thermometry. One concept for incorporating this phenomena into an optical fiber based sensor involves bonding the optically active material to the cladding of an optical fiber and allowing the luminescent light to couple into the the fiber by the evanescent wave. Experimental work developing this concept has already been reported. Measurements of the linewidth of Eu3+:Y2O3, diffused into a fiber, made by Albin clearly show a strong and regular dependence on temperature over the range of 300 to 1000 K. We report here on a study of the temperature dependence of the lineshape of the emission at 611 nm using the data in references. We focus attention on understanding the general behavior of the Eu3+:Y2O3 system. Building upon understanding of this system we will be able to establish the physical criterial for a good optical fiber based temperature sensor and then to examine available data on other lanthanide rare earths and transition metal ions to determine the best luminescent system for temperature sensing in an optical fiber.

  1. Luminescence property and emission enhancement of YbAlO3:Mn4+ red phosphor by Mg2+ or Li+ ions

    NASA Astrophysics Data System (ADS)

    Cao, Renping; Luo, Wenjie; Xu, Haidong; Luo, Zhiyang; Hu, Qianglin; Fu, Ting; Peng, Dedong

    2016-03-01

    YbAlO3:Mn4+, YbAlO3:Mn4+, Li+, and YbAlO3:Mn4+, Mg2+ phosphors are synthesized by high temperature solid-state reaction method in air. Their crystal structures and luminescence properties are investigated. Photoluminescence excitation (PLE) spectrum monitored at 677 nm contains broad PLE band with three PLE peaks located at ∼318, 395, and 470 nm within the range 220-600 nm. Emission spectra with excitation 318 and 470 nm exhibit three emission band peaks located at ∼645, 677, and 700 nm in the range of 610-800 nm and their corresponding chromaticity coordinates are about (x = 0.6942, y = 0.3057). The possible luminous mechanism of Mn4+ ion is analyzed by the simple energy level diagram of Mn4+ ion. The optimum Mn4+-doped concentration in YbAlO3:Mn4+ phosphor is about 0.4 mol% and the luminescence lifetime of YbAlO3:0.4%Mn4+ phosphor is ∼0.59 ms. Emission intensity of YbAlO3:0.4%Mn4+ phosphor can be enhanced ∼6 times after Mg2+ ion is co-doped and it is ∼2 times when Li+ ion is co-doped. The content in the paper is useful to research new Mn4+-doped luminescence materials and improve luminescence property of other Mn4+-doped phosphors.

  2. Functional properties of flagellin as a stimulator of innate immunity

    PubMed Central

    Lu, Yuan; Swartz, James R.

    2016-01-01

    We report the development of a well-defined flagellin-based nanoparticle stimulator and also provide a new mechanism of action model explaining how flagellin-triggered innate immunity has evolved to favor localized rather than potentially debilitating systemic immune stimulation. Cell-free protein synthesis (CFPS) was used to facilitate mutational analysis and precisely orientated display of flagellin on Hepatitis B core (HBc) protein virus-like particles (VLPs). The need for product stability and an understanding of mechanism of action motivated investigations indicating that the D0 domain of flagellin is sensitive to amino acid sequence independent hydrolysis – apparently due to the need for structural flexibility during natural flagellin polymerization. When D0-stabilized flagellin was attached to HBc VLPs with the D0 domain facing outward, flagellin’s tendency to polymerize caused the VLPs to precipitate. However, attaching the D0 domain to the VLP surface produced a stable nanoparticle adjuvant. Surprisingly, attaching only 2 flagellins per VLP provided the same 1 pM potency as did VLPs with about 33 attached flagellins suggesting that the TLR5 receptor is highly effective in delivering its intracellular signal. These observations suggest that flagellin’s protease sensitivity, tendency to aggregate, and very high affinity for TLR5 receptors limit its systemic distribution to favor localized immune stimulation. PMID:26755208

  3. Estimating dose to implantable cardioverter-defibrillator outside the treatment fields using a skin QED diode, optically stimulated luminescent dosimeters, and LiF thermoluminescent dosimeters

    SciTech Connect

    Chan, Maria F.; Song, Yulin; Dauer, Lawrence T.; Li Jingdong; Huang, David; Burman, Chandra

    2012-10-01

    The purpose of this work was to determine the relative sensitivity of skin QED diodes, optically stimulated luminescent dosimeters (OSLDs) (microStar Trade-Mark-Sign DOT, Landauer), and LiF thermoluminescent dosimeters (TLDs) as a function of distance from a photon beam field edge when applied to measure dose at out-of-field points. These detectors have been used to estimate radiation dose to patients' implantable cardioverter-defibrillators (ICDs) located outside the treatment field. The ICDs have a thin outer case made of 0.4- to 0.6-mm-thick titanium ({approx}2.4-mm tissue equivalent). A 5-mm bolus, being the equivalent depth of the devices under the patient's skin, was placed over the ICDs. Response per unit absorbed dose-to-water was measured for each of the dosimeters with and without bolus on the beam central axis (CAX) and at a distance up to 20 cm from the CAX. Doses were measured with an ionization chamber at various depths for 6- and 15-MV x-rays on a Varian Clinac-iX linear accelerator. Relative sensitivity of the detectors was determined as the ratio of the sensitivity at each off-axis distance to that at the CAX. The detector sensitivity as a function of the distance from the field edge changed by {+-} 3% (1-11%) for LiF TLD-700, decreased by 10% (5-21%) for OSLD, and increased by 16% (11-19%) for the skin QED diode (Sun Nuclear Corp.) at the equivalent depth of 5 mm for 6- or 15-MV photon energies. Our results showed that the use of bolus with proper thickness (i.e., {approx}d{sub max} of the photon energy) on the top of the ICD would reduce the scattered dose to a lower level. Dosimeters should be calibrated out-of-field and preferably with bolus equal in thickness to the depth of interest. This can be readily performed in clinic.

  4. Development and implementation of a remote audit tool for high dose rate (HDR) Ir-192 brachytherapy using optically stimulated luminescence dosimetry

    PubMed Central

    Casey, Kevin E.; Alvarez, Paola; Kry, Stephen F.; Howell, Rebecca M.; Lawyer, Ann; Followill, David

    2013-01-01

    Purpose: The aim of this work was to create a mailable phantom with measurement accuracy suitable for Radiological Physics Center (RPC) audits of high dose-rate (HDR) brachytherapy sources at institutions participating in National Cancer Institute-funded cooperative clinical trials. Optically stimulated luminescence dosimeters (OSLDs) were chosen as the dosimeter to be used with the phantom. Methods: The authors designed and built an 8 × 8 × 10 cm3 prototype phantom that had two slots capable of holding Al2O3:C OSLDs (nanoDots; Landauer, Glenwood, IL) and a single channel capable of accepting all 192Ir HDR brachytherapy sources in current clinical use in the United States. The authors irradiated the phantom with Nucletron and Varian 192Ir HDR sources in order to determine correction factors for linearity with dose and the combined effects of irradiation energy and phantom characteristics. The phantom was then sent to eight institutions which volunteered to perform trial remote audits. Results: The linearity correction factor was kL = (−9.43 × 10−5 × dose) + 1.009, where dose is in cGy, which differed from that determined by the RPC for the same batch of dosimeters using 60Co irradiation. Separate block correction factors were determined for current versions of both Nucletron and Varian 192Ir HDR sources and these vendor-specific correction factors differed by almost 2.6%. For the Nucletron source, the correction factor was 1.026 [95% confidence interval (CI) = 1.023–1.028], and for the Varian source, it was 1.000 (95% CI = 0.995–1.005). Variations in lateral source positioning up to 0.8 mm and distal/proximal source positioning up to 10 mm had minimal effect on dose measurement accuracy. The overall dose measurement uncertainty of the system was estimated to be 2.4% and 2.5% for the Nucletron and Varian sources, respectively (95% CI). This uncertainty was sufficient to establish a ±5% acceptance criterion for source strength audits under a formal RPC

  5. Technical Note: Precision and accuracy of a commercially available CT optically stimulated luminescent dosimetry system for the measurement of CT dose index

    PubMed Central

    Vrieze, Thomas J.; Sturchio, Glenn M.; McCollough, Cynthia H.

    2012-01-01

    Purpose: To determine the precision and accuracy of CTDI100 measurements made using commercially available optically stimulated luminescent (OSL) dosimeters (Landaur, Inc.) as beam width, tube potential, and attenuating material were varied. Methods: One hundred forty OSL dosimeters were individually exposed to a single axial CT scan, either in air, a 16-cm (head), or 32-cm (body) CTDI phantom at both center and peripheral positions. Scans were performed using nominal total beam widths of 3.6, 6, 19.2, and 28.8 mm at 120 kV and 28.8 mm at 80 kV. Five measurements were made for each of 28 parameter combinations. Measurements were made under the same conditions using a 100-mm long CTDI ion chamber. Exposed OSL dosimeters were returned to the manufacturer, who reported dose to air (in mGy) as a function of distance along the probe, integrated dose, and CTDI100. Results: The mean precision averaged over 28 datasets containing five measurements each was 1.4% ± 0.6%, range = 0.6%–2.7% for OSL and 0.08% ± 0.06%, range = 0.02%–0.3% for ion chamber. The root mean square (RMS) percent differences between OSL and ion chamber CTDI100 values were 13.8%, 6.4%, and 8.7% for in-air, head, and body measurements, respectively, with an overall RMS percent difference of 10.1%. OSL underestimated CTDI100 relative to the ion chamber 21/28 times (75%). After manual correction of the 80 kV measurements, the RMS percent differences between OSL and ion chamber measurements were 9.9% and 10.0% for 80 and 120 kV, respectively. Conclusions: Measurements of CTDI100 with commercially available CT OSL dosimeters had a percent standard deviation of 1.4%. After energy-dependent correction factors were applied, the RMS percent difference in the measured CTDI100 values was about 10%, with a tendency of OSL to underestimate CTDI relative to the ion chamber. Unlike ion chamber methods, however, OSL dosimeters allow measurement of the radiation dose profile. PMID:23127052

  6. Optically stimulated luminescence (OSL) of carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) for film dosimetry in radiotherapy

    SciTech Connect

    Schembri, V.; Heijmen, B. J. M.

    2007-06-15

    Introduction and Purpose: Conventional x-ray films and radiochromic films have inherent challenges for high precision radiotherapy dosimetry. Here we have investigated basic characteristics of optically stimulated luminescence (OSL) of irradiated films containing carbon-doped aluminum oxide (Al{sub 2}O{sub 3}:C) for dosimetry in therapeutic photon and electron beams. Materials and Methods: The OSL films consist of a polystyrene sheet, with a top layer of a mixture of single crystals of Al{sub 2}O{sub 3}:C, ground into a powder, and a polyester base. The total thickness of the films is 0.3 mm. Measurements have been performed in a water equivalent phantom, using 4, 6, 10, and 18 MV photon beams, and 6-22 MeV electron beams. The studies include assessment of the film response (acquired OSL signal/delivered dose) on delivered dose (linearity), dose rate (1-6 Gy/min), beam quality, field size and depth (6 MV, ranges 4x4-30x30 cm{sup 2}, d{sub max}-35 cm). Doses have been derived from ionization chamber measurements. OSL films have also been compared with conventional x-ray and GafChromic films for dosimetry outside the high dose area, with a high proportion of low dose scattered photons. In total, 787 OSL films have been irradiated. Results: Overall, the OSL response for electron beams was 3.6% lower than for photon beams. Differences between the various electron beam energies were not significant. The 6 and 18 MV photon beams differed in response by 4%. No response dependencies on dose rate were observed. For the 6 MV beam, the field size and depth dependencies of the OSL response were within {+-}2.5%. The observed inter-film response variation for films irradiated with the same dose varied from 1% to 3.2% (1 SD), depending on the measurement day. At a depth of 20 cm, 5 cm outside the 20x20 cm{sup 2} 6 and 18 MV beams, an over response of 17% was observed. In contrast to GafChromic and conventional x-ray films, the response of the Al{sub 2}O{sub 3}:C films is linear

  7. Development and implementation of a remote audit tool for high dose rate (HDR) Ir-192 brachytherapy using optically stimulated luminescence dosimetry

    SciTech Connect

    Casey, Kevin E.; Kry, Stephen F.; Howell, Rebecca M.; Followill, David; Alvarez, Paola; Lawyer, Ann

    2013-11-15

    Purpose: The aim of this work was to create a mailable phantom with measurement accuracy suitable for Radiological Physics Center (RPC) audits of high dose-rate (HDR) brachytherapy sources at institutions participating in National Cancer Institute-funded cooperative clinical trials. Optically stimulated luminescence dosimeters (OSLDs) were chosen as the dosimeter to be used with the phantom.Methods: The authors designed and built an 8 × 8 × 10 cm{sup 3} prototype phantom that had two slots capable of holding Al{sub 2}O{sub 3}:C OSLDs (nanoDots; Landauer, Glenwood, IL) and a single channel capable of accepting all {sup 192}Ir HDR brachytherapy sources in current clinical use in the United States. The authors irradiated the phantom with Nucletron and Varian {sup 192}Ir HDR sources in order to determine correction factors for linearity with dose and the combined effects of irradiation energy and phantom characteristics. The phantom was then sent to eight institutions which volunteered to perform trial remote audits.Results: The linearity correction factor was k{sub L}= (−9.43 × 10{sup −5}× dose) + 1.009, where dose is in cGy, which differed from that determined by the RPC for the same batch of dosimeters using {sup 60}Co irradiation. Separate block correction factors were determined for current versions of both Nucletron and Varian {sup 192}Ir HDR sources and these vendor-specific correction factors differed by almost 2.6%. For the Nucletron source, the correction factor was 1.026 [95% confidence interval (CI) = 1.023–1.028], and for the Varian source, it was 1.000 (95% CI = 0.995–1.005). Variations in lateral source positioning up to 0.8 mm and distal/proximal source positioning up to 10 mm had minimal effect on dose measurement accuracy. The overall dose measurement uncertainty of the system was estimated to be 2.4% and 2.5% for the Nucletron and Varian sources, respectively (95% CI). This uncertainty was sufficient to establish a ±5% acceptance

  8. Technical Note: Precision and accuracy of a commercially available CT optically stimulated luminescent dosimetry system for the measurement of CT dose index

    SciTech Connect

    Vrieze, Thomas J.; Sturchio, Glenn M.; McCollough, Cynthia H.

    2012-11-15

    Purpose: To determine the precision and accuracy of CTDI{sub 100} measurements made using commercially available optically stimulated luminescent (OSL) dosimeters (Landaur, Inc.) as beam width, tube potential, and attenuating material were varied. Methods: One hundred forty OSL dosimeters were individually exposed to a single axial CT scan, either in air, a 16-cm (head), or 32-cm (body) CTDI phantom at both center and peripheral positions. Scans were performed using nominal total beam widths of 3.6, 6, 19.2, and 28.8 mm at 120 kV and 28.8 mm at 80 kV. Five measurements were made for each of 28 parameter combinations. Measurements were made under the same conditions using a 100-mm long CTDI ion chamber. Exposed OSL dosimeters were returned to the manufacturer, who reported dose to air (in mGy) as a function of distance along the probe, integrated dose, and CTDI{sub 100}. Results: The mean precision averaged over 28 datasets containing five measurements each was 1.4%{+-} 0.6%, range = 0.6%-2.7% for OSL and 0.08%{+-} 0.06%, range = 0.02%-0.3% for ion chamber. The root mean square (RMS) percent differences between OSL and ion chamber CTDI{sub 100} values were 13.8%, 6.4%, and 8.7% for in-air, head, and body measurements, respectively, with an overall RMS percent difference of 10.1%. OSL underestimated CTDI{sub 100} relative to the ion chamber 21/28 times (75%). After manual correction of the 80 kV measurements, the RMS percent differences between OSL and ion chamber measurements were 9.9% and 10.0% for 80 and 120 kV, respectively. Conclusions: Measurements of CTDI{sub 100} with commercially available CT OSL dosimeters had a percent standard deviation of 1.4%. After energy-dependent correction factors were applied, the RMS percent difference in the measured CTDI{sub 100} values was about 10%, with a tendency of OSL to underestimate CTDI relative to the ion chamber. Unlike ion chamber methods, however, OSL dosimeters allow measurement of the radiation dose profile.

  9. SU-D-304-06: Measurement of LET in Patient-Specific Proton Therapy Treatment Fields Using Optically Stimulated Luminescence Detectors

    SciTech Connect

    Granville, DA; Sahoo, N; Sawakuchi, GO

    2015-06-15

    Purpose: To investigate the use of optically stimulated luminescence (OSL) detectors (OSLDs) for measurements of dose-averaged linear energy transfer (LET) in patient-specific proton therapy treatment fields. Methods: We used Al{sub 2}O{sub 3}:C OSLDs made from the same material as commercially available nanoDot OSLDs from Landauer, Inc. We calibrated two parameters of the OSL signal as functions of LET in therapeutic proton beams: the ratio of the ultraviolet and blue emission intensities (UV/blue ratio) and the OSL curve shape. These calibration curves were created by irradiating OSLDs in passively scattered beams of known LET (0.96 to 3.91 keV/µm). The LET values were determined using a validated Monte Carlo model of the beamline. We then irradiated new OSLDs with the prescription dose (16 to 74 cGy absorbed dose to water) at the center of the spread-out Bragg peak (SOBP) of four patient-specific treatment fields. From readouts of these OSLDs, we determined both the UV/blue ratio and OSL curve shape parameters. Combining these parameters with the calibration curves, we were able to measure LET using the OSLDs. The measurements were compared to the theoretical LET values obtained from Monte Carlo simulations of the patient-specific treatments fields. Results: Using the UV/blue ratio parameter, we were able to measure LET within 3.8%, 6.2%, 5.6% and 8.6% of the Monte Carlo value for each of the patient fields. Similarly, using the OSL curve shape parameter, LET measurements agreed within 0.5%, 11.0%, 2.5% and 7.6% for each of the four fields. Conclusion: We have demonstrated a method to verify LET in patient-specific proton therapy treatment fields using OSLDs. The possibility of enhancing biological effectiveness of proton therapy treatment plans by including LET in the optimization has been previously shown. The LET verification method we have demonstrated will be useful in the quality assurance of such LET optimized treatment plans. DA Granville received

  10. Synthesis, structure and luminescence property of 2D lanthanide complexes with 3-fluorophthalate and oxalate

    SciTech Connect

    Cha, Yu-E; Li, Xia; Song, Shuang

    2012-12-15

    Complexes [Ln{sub 2}(fpht){sub 2}(ox)(H{sub 2}O){sub 4}]{center_dot}H{sub 2}O (Ln=Sm 1, Eu 2, Tb 3 and Dy 4; fpht=3-fluorophthalate and ox=oxalate) have been synthesized and structurally characterized by single crystal X-ray diffraction. The four complexes possess similar 2D framework structures constructed from Ln-fpht double-stranded helices and ox linkages. Complexes 2 and 3 display the characteristic emission {sup 5}D{sub 0}{yields}{sup 7}F{sub J} (J=0-4) transitions of Eu(III) ion and {sup 5}D{sub 4}{yields}{sup 7}F{sub J} (J=6-3) transitions of Tb(III) ion, respectively. The emission decay curves reveal a monoexponential behavior yielding the lifetime values of 0.266{+-}0.002 ms for 2 and 0.733{+-}0.002 ms for 3. The emission spectrum of 1 shows three weak bands corresponding to the characteristic emission {sup 4}G{sub 5/2}{yields}{sup 6}H{sub 5/2}, {sup 4}G{sub 5/2}{yields}{sup 6}H{sub 7/2} and {sup 4}G{sub 5/2}{yields}{sup 6}H{sub 9/2} transitions of Sm(III) ion. The emission spectrum of 4 displays a broad band centered at 438 nm, which comes from the {pi}{sup Low-Asterisk }-{pi} transition of the ligand. - Graphical abstract: Complexes [Ln{sub 2}(fpht){sub 2}(ox)(H{sub 2}O){sub 4}]{center_dot}H{sub 2}O (fpht=3-fluorophthalate, ox=oxalate) possess 2D structures. Sm(III), Eu(III) and Tb(III) complexes show the characteristic fluorescent emission of the Ln(III). Dy(III) complex displays ligand-based luminescent behavior. Highlights: Black-Right-Pointing-Pointer [Ln{sub 2}(fpht){sub 2}(ox)(H{sub 2}O){sub 4}]{center_dot}H{sub 2}O (fpht=3-fluorophthalate; ox=oxalate) show 2D structures. Black-Right-Pointing-Pointer The 2D structures are constructed from Ln-fpht double-stranded helices and ox linkage. Black-Right-Pointing-Pointer The Sm(III), Eu(III) and Tb(III) complexes show the characteristic emission of the Ln(III) ions. Black-Right-Pointing-Pointer Dy(III) complex displays ligand-based luminescent behavior.

  11. Synthesis and luminescence properties of encapsulated sol-gel glass samarium complexes

    NASA Astrophysics Data System (ADS)

    Zaitoun, M. A.; Momani, K.; Jaradat, Q.; Qurashi, I. M.

    2013-11-01

    Luminescence efficiency of lanthanide complexes generally largely depend on the choice of the organic ligand and the host matrix in which these complexes are doped. Two Sm(III) complexes, namely: Sm(III) dithicarbamate - Sm(L1)3B [L1 = (R)2NCS2B, R = C2H5 and B = 1,10-phenanthroline] and Sm(III) complex with the polytonic ligand L2 = N‧, N‧2-bis[(1E)-1-(2-pyridyl)ethylidene]ethanedihydrazide {Sm2-L2-(CH3COO)2; L2 = C16H16N6O2} are synthesized, these complexes are then trapped in sol-gel glass. Room temperature luminescence of Sm(L1)3B and {Sm2-L2-(CH3COO)2} complexes encapsulated in sol-gel glass are studied using a spectrofluorometer. Up on excitation by a UV light, ligand L1B absorbs this light and transfers it into the Sm(III) ions and emission bands were observed in the visible region and were attributed to f-f transitions of Sm(III). The observed emission indicated an efficient L1B ligand as a sensitizer, while ligand L2 shows no ability to work as a sensitizer. The branching ratio I4G5/2→6H9/2/I4G5/2→6H7/2) of electric dipole transition to magnetic dipole transition was used as an effective spectroscopic probe to predict symmetry of the site in which Sm(III) is located. The encapsulation of the Samaium complexes was performed for three reasons: (i) before rare earth (RE)-doped sol-gel glasses can be used in applications such as laser materials, several fluorescence quenching mechanisms must be overcome, we show in this work that lanthanide fluorescence is greatly enhanced by chelation and selecting a suitable host matrix (sol-gel) to accommodate the lanthanide complex, (ii) to improve the stability of the phosphor with efficient and high color-purity characteristics under ultraviolet excitation and (iii) this work provides a framework for preparing transparent composite glasses that are robust hosts to study the fundamental interactions between nano-materials and light.

  12. Platinum diimine bis(acetylide) complexes: Synthesis, characterization, and luminescence properties

    SciTech Connect

    Hissler, M.; Connick, W.B.; Geiger, D.K.; McGarrah, J.E.; Lipa, D.; Lachicotte, R.J.; Eisenberg, R.

    2000-02-07

    A new set of luminescent platinum(II) diimine complexes has been synthesized and characterized. The anionic ligands in these complexes are arylacetylides. The complexes are brightly emissive in fluid solution with relative emission quantum yields {phi}{sub em} ranging from 3 x 10{sup {minus}3} to 10{sup {minus}1}. Two series of complexes have been investigated. The first has the formula Pt(Rphen)(C{equivalent{underscore}to}CC{sub 6}H{sub 5}){sub 2} where Rphen is 1,10-phenanthroline substituted in the 5-position with R = H, Me, Cl, Br, NO{sub 2}, or C{equivalent{underscore}to}CC{sub 6}H{sub 5}, while the second has the formula Pt(dbbpy)(C{equivalent{underscore}to}CC{sub 6}H{sub 4}X){sub 2} where dbbpy = 4,4{prime}-di(tert-butyl)bipyridine and X = H, Me, F, or NO{sub 2}. From NMR, IR, and electronic spectroscopies, all of the complexes are assigned a square planar coordination geometry with cis-alkynyl ligands. The crystal structure of Pt(phen)(C{equivalent{underscore}to}CC{sub 6}H{sub 4}CH{sub 3}){sub 2} confirms this assignment. All of the complexes exhibit an absorption band at ca. 400 nm that corresponds to a Pt d {r{underscore}arrow} {pi}{asterisk}{sub diimine} charge-transfer transition. The variation of {lambda}{sub max} for this band with substituent variation supports this assignment. From similar changes in the energy of the solution luminescence as a function of substituents R and X, the emissive excited state is also of MLCT origin, but with spin-forbidden character on the basis of excited-state lifetime measurements (0.01--5.6 {mu}s). The complexes undergo electron-transfer quenching, showing good Stern-Volmer behavior using 10-methylphenothiazine and N,N,N{prime},N{prime}-tetramethylbenzidine as reductive quenchers. Excited-state reduction potentials are estimated on the basis of a simple thermochemical analysis. Crystal data for Pt(phen)(C{equivalent{underscore}to}CC{sub 6}H{sub 4}CH{sub 3}){sub 2}: monoclinic, space group C2/c, a = 19

  13. Platinum diimine bis(acetylide) complexes: synthesis, characterization, and luminescence properties.

    PubMed

    Hissler, M; Connick, W B; Geiger, D K; McGarrah, J E; Lipa, D; Lachicotte, R J; Eisenberg, R

    2000-02-01

    A new set of luminescent platinum(II) diimine complexes has been synthesized and characterized. The anionic ligands in these complexes are arylacetylides. The complexes are brightly emissive in fluid solution with relative emission quantum yields phiem ranging from 3 x 10(-3) to 10(-1). Two series of complexes have been investigated. The first has the formula Pt(Rphen)(C...CC6H5)2 where Rphen is 1,10-phenanthroline substituted in the 5-position with R = H, Me, Cl, Br, NO2, or C...CC6H5, while the second has the formula Pt(dbbpy)(C=CC6H4X)2 where dbbpy = 4,4'-di(tert-butyl)bipyridine and X = H, Me, F, or NO2. From NMR, IR, and electronic spectroscopies, all of the complexes are assigned a square planar coordination geometry with cis-alkynyl ligands. The crystal structure of Pt(phen)(Ce-CC6H4CH3)2 confirms this assignment. All of the complexes exhibit an absorption band at ca. 400 nm that corresponds to a Pt d-->pi*diimine charge-transfer transition. The variation of lambdamax for this band with substituent variation supports this assignment. From similar changes in the energy of the solution luminescence as a function of substituents R and X, the emissive excited state is also of MLCT origin, but with spin-forbidden character on the basis of excited-state lifetime measurements (0.01-5.6 micros). The complexes undergo electron-transfer quenching, showing good Stern-Volmer behavior using 10-methylphenothiazine and N,N,N',N'-tetramethylbenzidine as reductive quenchers. Excited-state reduction potentials are estimated on the basis of a simple thermochemical analysis. Crystal data for Pt(phen)(C...CC6H4CH3)2: monoclinic, space group C2/c, a = 19.0961(1) A, b = 10.4498(1) A, c = 11.8124(2) A, beta = 108.413(1) degrees, V = 2236.49 A3, number of reflections 1614, number of variables 150, R1 = 0.0163, wR2 (I > 2sigma) = 0.0410. PMID:11229561

  14. Understanding the infrared to visible upconversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals

    SciTech Connect

    Adhikari, Rajesh; Choi, Jinhyuk; Narro-García, R.; De la Rosa, E.; Sekino, Tohru; Lee, Soo Wohn

    2014-08-15

    In this paper we report the infrared to visible upconversion luminescence properties of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals synthesized via microwave assisted sol–gel processing route. Structural, morphological and upconversion luminescence properties were investigated by X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), UV–vis diffuse reflectance spectroscopy (UV–vis DRS) and Upconversion Photoluminescence spectra analysis. Results revealed that the oval shaped BaMoO{sub 4} nanocrystals ranging in size from 40 to 60 nm having tetragonal scheelite crystal structure were obtained by sol–gel route. The infrared to visible upconversion luminescence has been investigated in Er{sup 3+}/Yb{sup 3+} co-doped in BaMoO{sub 4}with different Yb{sup 3+} concentrations. Intense green upconversion emissions around 528, 550 nm, and red emission at 657 nm corresponding to the {sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}, and {sup 4}F{sub 9/2} transitions, respectively to the {sup 4}I{sub 15/2} ground state were observed when excited by CW laser radiation at 980 nm. The green emissions were greatly enhanced after the addition of sensitizer (Yb{sup 3+} ions). The effect of Yb{sup 3+} on the upconversion luminescence intensity was analyzed and explained in terms of the energy transfer process based. The reported work establishes the understanding of molybdates as an alternative host material for upconversion luminescence. - Graphical abstract: Infrared to visible upconversion luminescence of Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals. - Highlights: • Nanocrystals were synthesized by microwave assisted sol–gel processing route. • Strong green emissions were observed in Er{sup 3+}/Yb{sup 3+} co-doped BaMoO{sub 4} nanocrystals. • Provides an insight on Upconversion luminescence properties of oxides host materials.

  15. Boron clusters in luminescent materials.

    PubMed

    Mukherjee, Sanjoy; Thilagar, Pakkirisamy

    2016-01-21

    In recent times, luminescent materials with tunable emission properties have found applications in almost all aspects of modern material sciences. Any discussion on the recent developments in luminescent materials would be incomplete if one does not account for the versatile photophysical features of boron containing compounds. Apart from triarylboranes and tetra-coordinate borate dyes, luminescent materials consisting of boron clusters have also found immense interest in recent times. Recent studies have unveiled the opportunities hidden within boranes, carboranes and metalloboranes, etc. as active constituents of luminescent materials. From simple illustrations of luminescence, to advanced applications in LASERs, OLEDs and bioimaging, etc., the unique features of such compounds and their promising versatility have already been established. In this review, recent revelations about the excellent photophysical properties of such materials are discussed. PMID:26574714

  16. Structure and Luminescence Properties of Eu3+-Doped Cubic Mesoporous Silica Thin Films

    PubMed Central

    2010-01-01

    Eu3+ ions-doped cubic mesoporous silica thin films with a thickness of about 205 nm were prepared on silicon and glass substrates using triblock copolymer as a structure-directing agent using sol–gel spin-coating and calcination processes. X-ray diffraction and transmission electron microscopy analysis show that the mesoporous silica thin films have a highly ordered body-centered cubic mesoporous structure. High Eu3+ ion loading and high temperature calcination do not destroy the ordered cubic mesoporous structure of the mesoporous silica thin films. Photoluminescence spectra show two characteristic emission peaks corresponding to the transitions of5D0-7F1 and 5D0-7F2 of Eu3+ ions located in low symmetry sites in mesoporous silica thin films. With the Eu/Si molar ratio increasing to 3.41%, the luminescence intensity of the Eu3+ ions-doped mesoporous silica thin films increases linearly with increasing Eu3+ concentration. PMID:20672132

  17. Uncommon Pyrazoyl-Carboxyl Bifunctional Ligand-Based Microporous Lanthanide Systems: Sorption and Luminescent Sensing Properties.

    PubMed

    Li, Gao-Peng; Liu, Ge; Li, Yong-Zhi; Hou, Lei; Wang, Yao-Yu; Zhu, Zhonghua

    2016-04-18

    Seven new isostructural lanthanide metal-organic frameworks (Ln-MOFs), [Ln(Hpzbc)2(NO3)]·H2O (1-Ln, Ln = Nd(3+), Sm(3+), Eu(3+), Gd(3+), Tb(3+), Er(3+), and Yb(3+) ions, H2pzbc = 3-(1H-pyrazol-3-yl) benzoic acid), with one-dimensional (1D) channels decorated by nitrate anions and pyrazoyl groups have been constructed. 1-Ln, as revealed by structural analysis, represent uncommon microporous 3D Ln-pyrazoyl-carboxyl systems using pyrazoyl-carboxyl bifunctional ligands as bridges. The luminescent investigations show that 1-Eu is an excellent MOF-based fluorescent probe, with high sensitivity, selectivity, and simple regeneration, for environmentally relevant Fe(3+) and Cr2O7(2-) ions. 1-Eu also presents highly selective capture for CO2 over N2 and CH4 due to the multiple binding sites for CO2 molecules, which were supported by Grand Canonical Monte Carlo (GCMC) simulations. PMID:27022691

  18. Synthesis and Luminescence Properties of La2W2O9:Eu3+ Micron-Crystals.

    PubMed

    Zhang, Jiao; Yang, Yanmin; Yu, Fang; Liu, Yanzhou; Han, Boning; Mi, Chao; Liu, Linlin

    2016-04-01

    La2W2O9:2%Eu3+ phosphors were synthesized by a typical hydrothermal procedure. The samples were characterized by X-ray diffraction and scanning electron microscope (SEM). X-ray diffraction analysis showed that a stock solution pH value equal to 9 is the ideal value, while the crystallization of the hydroxyl sodium yttrium tungstate crystal is improved by increasing the PH values of stock solution within limits. Meanwhile, SEMs of different pH values were recorded. Additionally, photo-luminescence excitation (PLE) and emission (PL) spectra were measured. It was found that this phosphor can be effectively excited by C-T band (266 nm) and ultraviolet light 342 nm. The wave-lengths at 342 nm fit in nicely with the whole visible region, thus the La2W2O9:2%Eu3+ phosphors emit white light. Furthermore, the annealing temperature's impact on PLE and PL spectra was also studied. The Eu3+-doped La2W2O9 phosphor may be a better candidate than current method for solid-state lighting applications. PMID:27451723

  19. Synthesis, structure and luminescence property of the three ternary and quaternary europium complexes

    NASA Astrophysics Data System (ADS)

    Li, X.; Jin, L. P.; Zheng, X. J.; Lu, S. Z.; Zhang, J. H.

    2002-04-01

    Three binuclear europium complexes containing bidentate and tridentate bridging carboxylates with diimines, namely [Eu( m-MOBA) 2NO 3phen] 2, [Eu(2,3-DMOBA) 2NO 3phen] 2 and [Eu(2,3-DMOBA) 3bpy] 2 ( m-MOBA=3-methoxybenzoate, 2,3-DMOBA=2,3-dimethoxy-benzoate, phen=1,10-phenanthroline, bpy=2,2'-bipyridine), have been synthesized and characterized by X-ray diffraction. The two europium(III) ions in each dimer are bridged by the four carboxylato groups in which two of them are the bidentate bridging mode, and the other two the tridentate bridging mode. The crystallographic data and combination bands of infrared spectra of the [Eu( m-MOBA) 2NO 3phen] 2 and the [Eu(2,3-DMOBA) 2NO 3phen] 2 complexes show that the nitrato group is bidentate, and thus each europium(III) ion in the complexes is coordinated with seven oxygen atoms and two nitrogen atoms from phen, leading to a dimeric structure with coordination number 9. Excitation and emission spectra of the europium complexes were observed at 77 K. The 5D0→ 7FJ ( J=0-4) luminescence spectra show that the europium(III) ion site in the crystals of the three europium complexes has C1 symmetry. The slightly different chemical environments of the europium(III) ions in the [Eu(2,3-DMOBA) 3bpy] 2 complex is confirmed by its emission spectra.

  20. Effect of Eu, Tb codoping on the luminescent properties of Y2O3 hollow microspheres

    NASA Astrophysics Data System (ADS)

    Jiu, Hongfang; Fu, Yuehua; Zhang, Lixin; Sun, Yixin; Wang, Yuanzhong

    2012-12-01

    Y2O3:Eu3+, Tb3+ hollow microspheres are prepared with different doping concentration of Eu3+ and Tb3+ ions and synthesizing temperatures from 700 to 1000 °C via a urea-based homogeneous precipitation technique with colloidal melamine formaldehyde (MF) microspheres as templates followed by a subsequent calcination process. The resulted hollow microspheres were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and photoluminescence (PL) spectroscopy. The results of XRD indicate that the crystallinity of the synthesized samples increases with enhancing the calcination temperature. The photoluminescence spectra indicate the Eu3+ and Tb3+ co-doped Y2O3 microspheres show five main emission peaks: three at 591, 609 and 629 nm originate from Eu3+ and two at 482 and 541 nm originate from Tb3+, under excitation of 250-340 nm irradiation. The luminescence color could be changed by varying the excitation wavelength. Different concentrations of Eu3+ and Tb3+ ions were induced into the Y2O3 lattice and the energy transfer from Tb3+ to Eu3+ ions in these phosphors was found.

  1. Template synthesis and luminescence properties of TiO{sub 2}:Eu{sup 3+} nanotubes

    SciTech Connect

    Zhao, Huan; Zheng, Keyan; Sheng, Ye; Li, Hongbo; Zhang, Hongguang; Qi, Xiaofei; Shi, Zhan; Zou, Haifeng

    2014-02-15

    Uniform TiO{sub 2}:Eu{sup 3+} nanotubes have been successfully synthesized through a simple solvothermal process with carbon nanotubes (CNTs) as templates, free of any surfactant or catalyst. X-ray diffraction (XRD) results demonstrate that the product is a pure anatase phase of TiO{sub 2}. Scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images indicate that the as-obtained TiO{sub 2}:Eu{sup 3+} nanotubes are uniform in size and distribution, and the thickness of the wall is about 8 nm. The possible formation mechanism has also been proposed. The luminescent spectrum shows that TiO{sub 2}:Eu{sup 3+} nanotubes exhibit a red emission at 612 nm due to the {sup 5}D{sub 0}→{sup 7}F{sub 2} transition. Furthermore, this synthetic route is promising for the preparation of other one-dimensional inorganic nanomaterials because of its simplicity and the low cost of the starting reagents. - Graphical abstract: This picture is the illustration for the formation process of TiO{sub 2}:Eu{sup 3+} nanotubes. Display Omitted - Highlights: • TiO{sub 2}:Eu{sup 3+} nanotubes have been prepared through a simple solvothermal process. • The TiO{sub 2}:Eu{sup 3+} nanotubes are uniform in size and distribution. • Under UV light excitation, the TiO{sub 2}:Eu{sup 3+} nanotubes show strong red emission.

  2. Preparation, characterization and oxygen sensing properties of luminescent carbon dots assembled mesoporous silica microspheres.

    PubMed

    Wang, Li; Zhang, Haoran; Zhou, Xiaohua; Liu, Yingliang; Lei, Bingfu

    2016-09-15

    In this paper, our effort was focused on preparation and oxygen sensing of luminescence carbon dots (CDs) assembled hollow mesoporous silica microspheres (HMSMs) and mesoporous silica microspheres (MSMs). MSMs doped with CDs showed shorter response time and recovery time comparing with HMSMs doped with CDs. This feature can be attributed to ordered channel structure of mesoporous carrier which can promote the gas diffusion effectively. While HMSMs doped with CDs shows a higher oxygen quenching response and the degree of quenching reach 80.35%. The response time was determined to be about 7s and the emission intensities of the samples were effectively reduced as the concentration of oxygen increased. These results indicate that the system we have developed can be used for oxygen detection in wide concentration range and is especially accurate for very low oxygen concentrations. The obtained CDs grafted hollow mesoporous silica microspheres (HMSMs) and mesoporous silica microspheres (MSMs) samples appears to be a promising sensing material for environmental detection application and would also find applications in catalyst, electrode, or related fields. PMID:27309945

  3. Utilizing Nanofabrication to Construct Strong, Luminescent Materials

    SciTech Connect

    Chen, Wei; Huang, Gang; Lu, Hong B.; McCready, David E.; Joly, Alan G.; Bovin, Jan-Olov

    2006-05-28

    Luminescent materials have been utilized widely in applications from lighting to sensing. The new development of technologies based on luminescence properties requires the materials to have high luminescence efficiency and mechanical strength. In this article, we report the fabrication of luminescent materials possessing high mechanical strength by nanofabrication with polyvinyl alcohol used as a stabilizer or coupling agent. X-ray diffraction and high resolution transmission microscope observations reveal that the nanocomposite sample contains ZnS and ZnO nanoparticles as well as kozoite and sodium nitrate. The mechanical strength and hardness of these nanocomposite materials are higher than polycarbonate and some carbon nanotube reinforced nanocomposites. Strong luminescence is observed in the new nanocomposites and the luminescence intensity does not degrade following up to 30 minutes of X-ray irradiation. Our results indicate that nanofabrication may provide a good method to improve the mechanical strength of luminescent materials for some applications in which high strength luminescent materials are needed.

  4. The Luminescent Oligothiophene p-FTAA Converts Toxic Aβ1–42 Species into Nontoxic Amyloid Fibers with Altered Properties*

    PubMed Central

    Civitelli, Livia; Sandin, Linnea; Nelson, Erin; Khattak, Sikander Iqbal; Kågedal, Katarina

    2016-01-01

    Aggregation of the amyloid-β peptide (Aβ) in the brain leads to the formation of extracellular amyloid plaques, which is one of the pathological hallmarks of Alzheimer disease (AD). It is a general hypothesis that soluble prefibrillar assemblies of the Aβ peptide, rather than mature amyloid fibrils, cause neuronal dysfunction and memory impairment in AD. Thus, reducing the level of these prefibrillar species by using molecules that can interfere with the Aβ fibrillation pathway may be a valid approach to reduce Aβ cytotoxicity. Luminescent-conjugated oligothiophenes (LCOs) have amyloid binding properties and spectral properties that differ when they bind to protein aggregates with different morphologies and can therefore be used to visualize protein aggregates. In this study, cell toxicity experiments and biophysical studies demonstrated that the LCO p-FTAA was able to reduce the pool of soluble toxic Aβ species in favor of the formation of larger insoluble nontoxic amyloid fibrils, there by counteracting Aβ-mediated cytotoxicity. Moreover, p-FTAA bound to early formed Aβ species and induced a rapid formation of β-sheet structures. These p-FTAA generated amyloid fibrils were less hydrophobic and more resistant to proteolysis by proteinase K. In summary, our data show that p-FTAA promoted the formation of insoluble and stable Aβ species that were nontoxic which indicates that p-FTAA might have therapeutic potential. PMID:26907684

  5. The Luminescent Oligothiophene p-FTAA Converts Toxic Aβ1-42 Species into Nontoxic Amyloid Fibers with Altered Properties.

    PubMed

    Civitelli, Livia; Sandin, Linnea; Nelson, Erin; Khattak, Sikander Iqbal; Brorsson, Ann-Christin; Kågedal, Katarina

    2016-04-22

    Aggregation of the amyloid-β peptide (Aβ) in the brain leads to the formation of extracellular amyloid plaques, which is one of the pathological hallmarks of Alzheimer disease (AD). It is a general hypothesis that soluble prefibrillar assemblies of the Aβ peptide, rather than mature amyloid fibrils, cause neuronal dysfunction and memory impairment in AD. Thus, reducing the level of these prefibrillar species by using molecules that can interfere with the Aβ fibrillation pathway may be a valid approach to reduce Aβ cytotoxicity. Luminescent-conjugated oligothiophenes (LCOs) have amyloid binding properties and spectral properties that differ when they bind to protein aggregates with different morphologies and can therefore be used to visualize protein aggregates. In this study, cell toxicity experiments and biophysical studies demonstrated that the LCO p-FTAA was able to reduce the pool of soluble toxic Aβ species in favor of the formation of larger insoluble nontoxic amyloid fibrils, there by counteracting Aβ-mediated cytotoxicity. Moreover, p-FTAA bound to early formed Aβ species and induced a rapid formation of β-sheet structures. These p-FTAA generated amyloid fibrils were less hydrophobic and more resistant to proteolysis by proteinase K. In summary, our data show that p-FTAA promoted the formation of insoluble and stable Aβ species that were nontoxic which indicates that p-FTAA might have therapeutic potential. PMID:26907684

  6. Effect of potassium iodide on luminescent and photovoltaic properties of organic solar cells P3HT-PCBM

    NASA Astrophysics Data System (ADS)

    Ibrayev, N. Kh; Afanasyev, D. A.; Zhapabaev, K. A.

    2016-02-01

    It has been investigated spectral-luminescence properties of polymer films, doped with potassium iodide (KI). Using of KI didn't lead to the gradual changes of optical density of polymer films and the range of band gap semiconductor polymer P3HT. The fluorescence intensity of P3HT decreased and changed by use of KI. Using of 1% KI in polymer leaded to decrease of fluorescence lifetime. Influence of heavy atom on photovoltaic effect of organic solar cells has been investigated. 1% of KI in polymer film leaded to decrease of Isc and slightly decrease of Uoc. Investigation shows that magnetic field does not affect on photovoltaic properties of cells P3HT-PCBM. Magnetic field increased of open circuit voltage and short circuit current of solar cells with 1% of KI. Study of electrical impedance of cells revealed the magnetic sensivity of solar cells with KI additives. The lifetime of free charge carriers increased in the magnetic field for solar cells with KI additives.

  7. Synthesis, crystal structures and luminescent properties of zinc(II) metal–organic frameworks constructed from terpyridyl derivative ligand

    SciTech Connect

    Yang, Xiao-Le; Shangguan, Yi-Qing; Hu, Huai-Ming Xu, Bing; Wang, Bao-Cheng; Xie, Juan; Yuan, Fei; Yang, Meng-Lin; Dong, Fa-Xin; Xue, Gang-Lin

    2014-08-15

    Five zinc(II) metal–organic frameworks, [Zn{sub 3}(344-pytpy){sub 2}Cl{sub 6}]{sub n}·n(H{sub 2}O) (1), [Zn(344-pytpy)(ox)]{sub n} (2), [Zn{sub 2}(344-pytpy)(bdc){sub 2}]{sub n}·1.5n(H{sub 2}O) (3), [Zn{sub 2}(344-pytpy){sub 2} (sfdb){sub 2}]{sub n}·1.5n(H{sub 2}O) (4) and [Zn{sub 3}(344-pytpy){sub 2}(btc){sub 2}]{sub n}·2n(H{sub 2}O) (5), (344-pytpy=4′-(3-pyridyl)-4,2′:6′,4″-terpyridine, H{sub 2}ox=oxalic acid, H{sub 2}bdc=1,4-benzenedi-carboxylic acid, H{sub 2}sfdb=4,4′-sulfonyldibenzoic acid and H{sub 3}btc=1,3,5-benzene-tricarboxylic acid) have been prepared by hydrothermal reactions. Compound 1 is a 1D chain structure, in which 344-pytpy ligand links three Zn{sup II} centers through three of terminal N-donors. Compound 2 is a 4-connected 3D framework with the dia topological net and the Schläfli symbol of 6{sup 6}. Compound 3 displays a unusual 3-fold interpenetrating 3D coordination network which exhibits a new intriguing (3,3,4)-connected topological net with the Schläfli symbol of (4.8{sup 2})(4.8{sup 5})(8{sup 3}). Compound 4 features a two-fold interpenetrating 4-connected 2D framework with the sql topological net and the Schläfli symbol of (4{sup 4}.6{sup 2}). Compound 5 is a new self-interpenetrating (3,3,4,4)-connected topological net with the Schläfli symbol of (6.8{sup 2}){sub 2}(6{sup 2}.8{sup 2}.10.12)(6{sup 2}.8{sup 3}.10){sub 2}(6{sup 2}.8){sub 2}. The luminescence properties of 1–5 have been investigated by emission spectra and they possess great thermal stabilities which can be stable up to around 400 °C. - Graphical abstract: Five new Zn(II) metal–organic frameworks based on dicarboxylate and terpyridyl derivative ligands have been synthesized by hydrothermal reactions, giving networks from 1D to 3D structures. The thermal stability and luminescent property have been investigated. - Highlights: • Five zinc(II) metal–organic frameworks have been prepared under hydrothermal conditions. • Their crystal and

  8. Pulsed-Laser-Induced Simple Synthetic Route for Tb(3)Al(5)O(12):Ce Colloidal Nanocrystals and Their Luminescent Properties.

    PubMed

    Mhin, Sung Wook; Ryu, Jeong Ho; Kim, Kang Min; Park, Gyeong Seon; Ryu, Han Wool; Shim, Kwang Bo; Sasaki, Takeshi; Koshizaki, Naoto

    2009-01-01

    Cerium-doped Tb(3)Al(5)O(12) (TAG:Ce(3+)) colloidal nanocrystals were synthesized by pulsed laser ablation (PLA) in de-ionized water and lauryl dimethylaminoacetic acid betain (LDA) aqueous solution for luminescent bio-labeling application. The influence of LDA molecules on the crystallinity, crystal morphology, crystallite size, and luminescent properties of the prepared TAG:Ce(3+) colloidal nanocrystals was investigated in detail. When the LDA solution was used, smaller average crystallite size, narrower size distribution, and enhanced luminescence were observed. These characteristics were explained by the effective role of occupying the oxygen defects on the surface of TAG:Ce(3+) colloidal nanocrystal because the amphoteric LDA molecules were attached by positively charged TAG:Ce(3+) colloidal nanocrystals. The blue-shifted phenomena found in luminescent spectra of the TAG:Ce(3+) colloidal nanocrystals could not be explained by previous crystal field theory. We discuss the 5d energy level of Ce(3+) with decreased crystal size with a phenomenological model that explains the relationship between bond distance with 5d energy level of Ce(3+) based on the concept of crystal field theory modified by covalency contribution. PMID:20596420

  9. Pulsed-Laser-Induced Simple Synthetic Route for Tb3Al5O12:Ce3+ Colloidal Nanocrystals and Their Luminescent Properties

    NASA Astrophysics Data System (ADS)

    Mhin, Sung Wook; Ryu, Jeong Ho; Kim, Kang Min; Park, Gyeong Seon; Ryu, Han Wool; Shim, Kwang Bo; Sasaki, Takeshi; Koshizaki, Naoto

    2009-08-01

    Cerium-doped Tb3Al5O12 (TAG:Ce3+) colloidal nanocrystals were synthesized by pulsed laser ablation (PLA) in de-ionized water and lauryl dimethylaminoacetic acid betain (LDA) aqueous solution for luminescent bio-labeling application. The influence of LDA molecules on the crystallinity, crystal morphology, crystallite size, and luminescent properties of the prepared TAG:Ce3+ colloidal nanocrystals was investigated in detail. When the LDA solution was used, smaller average crystallite size, narrower size distribution, and enhanced luminescence were observed. These characteristics were explained by the effective role of occupying the oxygen defects on the surface of TAG:Ce3+ colloidal nanocrystal because the amphoteric LDA molecules were attached by positively charged TAG:Ce3+ colloidal nanocrystals. The blue-shifted phenomena found in luminescent spectra of the TAG:Ce3+ colloidal nanocrystals could not be explained by previous crystal field theory. We discuss the 5d energy level of Ce3+ with decreased crystal size with a phenomenological model that explains the relationship between bond distance with 5d energy level of Ce3+ based on the concept of crystal field theory modified by covalency contribution.

  10. Quantum chemistry-based interpretations on the lowest triplet state of luminescent lanthanides complexes. Part 1. Relation between the triplet state energy of hydroxamate complexes and their luminescence properties.

    PubMed

    Gutierrez, Fabien; Tedeschi, Christine; Maron, Laurent; Daudey, Jean-Pierre; Poteau, Romuald; Azema, Joëlle; Tisnès, Pierre; Picard, Claude

    2004-05-01

    In this paper, we evaluate the potential use of theoretical calculations to obtain an energy scale of the lowest ligand-centred triplet excited state in luminescent terbium(III) complexes. In these complexes, non-radiative deactivation of the terbium emitting state via a back-energy transfer process (T1<--Tb(5D4)) is a common quenching process. Consequently the prediction of the energy gap between these two excited states should be useful for programming highly luminescent Tb(III) systems. We report on a strategy based upon experimental and theoretical investigations of the excited state properties of a series of four simple aromatic hydroxamate ligands coordinated to Tb(III) and Gd(III) ions. By using previously reported crystallographic data, the structural and energies properties of these systems were investigated in the ground and first excited triplet states at the density functional theory (DFT) level of calculations. Our theoretical results are consistent with a triplet excited state T1 which is localised on one ligand only and whose the energy level is independent of the lanthanide ion nature (Tb(III), Gd(III)). A good agreement between the calculated adiabatic transition energies and experimental data derived from emission spectra is obtained when a corrective term is considered. These satisfactory results are an indication that this type of modelling can lead to discriminate in terms of the position of the lowest ligand triplet energy level the best antenna among a family of chromophoric compounds. In addition this theoretical approach has provided indications that the difference between the adiabatic transition energies of all the investigated complexes can be mainly explained by metal-ligand electrostatic interactions. The influence of the number of antennae on the quantum yield and the luminescence lifetime is discussed. PMID:15252626

  11. Chromophore-labelled, luminescent platinum complexes: syntheses, structures, and spectroscopic properties.

    PubMed

    Stacey, Oliver J; Ward, Benjamin D; Coles, Simon J; Horton, Peter N; Pope, Simon J A

    2016-06-21

    Ligands based upon 4-carboxamide-2-phenylquinoline derivatives have been synthesised with solubilising octyl hydrocarbon chains and tethered aromatic chromophores to give naphthyl (), anthracenyl () and pyrenyl () ligand variants, together with a non-chromophoric analogue () for comparison. (1)H NMR spectroscopic studies of the ligands showed that two non-interchangeable isomers exist for and while only one isomer exists for and . Supporting DFT calculations on suggest that the two isomers may be closely isoenergetic with a relatively high barrier to exchange of ca. 100 kJ mol(-1). These new ligands were cyclometalated with Pt(ii) to give complexes [Pt()(acac)] (acac = acetylacetonate). The spectroscopically characterised complexes were studied using multinuclear NMR spectroscopy including (195)Pt{(1)H} NMR studies which revealed δPtca. -2785 ppm for [Pt()(acac)]. X-ray crystallographic studies were undertaken on [Pt()(acac)] and [Pt()(acac)], each showing the weakly distorted square planar geometry at Pt(ii); the structure of [Pt()(acac)] showed evidence for intermolecular Pt-Pt interactions. The UV-vis. absorption studies show that the spectral profiles for [Pt()(acac)] are a composite of the organic chromophore centred bands and a broad (1)MLCT (5d → π*) band (ca. 440 nm) associated with the complex. Luminescence studies showed that complexes [Pt()(acac)] are dual emissive with fluorescence characteristic of the tethered fluorophore and long-lived phosphorescence attributed to (3)MLCT emission. In the case of the pyrenyl derivative, [Pt()(acac)], the close energetic matching of the (3)MLCT and (3)LCpyr excited states led to an elongation of the (3)MLCT emission lifetime (τ = 42 μs) under degassed solvent conditions, suggestive of energy transfer processes between the two states. PMID:27241625

  12. Syntheses, structures and luminescence properties of lanthanide coordination polymers with helical character

    SciTech Connect

    Zhou Ruisha; Cui Xiaobing; Song Jiangfeng; Xu Xiaoyu; Xu Jiqing Wang Tiegang

    2008-08-15

    A series of lanthanide coordination polymers, (Him){sub n}[Ln(ip){sub 2}(H{sub 2}O)]{sub n} [Ln=La(1), Pr(2), Nd(3) and Dy(4), H{sub 2}ip=isophthalic acid, im=imidazole] and [Y{sub 2}(ip){sub 3}(H{sub 2}O){sub 2}]{sub n}.nH{sub 2}O (5), have been synthesized and characterized by elemental analyses, infrared (IR), ultraviolet-visible-near infrared (UV-Vis-NIR) and single-crystal X-ray diffraction analyses. The isostructural compounds 1-4 possess 3-D structures with three different kinds of channels. Compound 5 features a 2-D network making of two different kinds of quadruple-helical chains. Compounds 2 and 3 present the characteristic emissions of Pr(III) and Nd(III) ions in NIR region, respectively. Compound 4 shows sensitized luminescence of Dy(III) ions in visible region. - Graphical abstract: A series of lanthanide coodination polymers, (Him){sub n}[Ln(ip){sub 2}(H{sub 2}O)]{sub n} [Ln=La(1), Pr(2), Nd(3) and Dy(4)] and [Y{sub 2}(ip){sub 3}(H{sub 2}O){sub 2}]{sub n}.nH{sub 2}O (5), have been reported. The isostructural compounds 1-4 possess 3-D structures with three different kinds of channels. Compound 5 displays a 2-D network making of two kinds of quadruple-helical chains. Display Omitted.

  13. Unexpected luminescent and quenching properties of metalloporphyrins in Langmuir-Blodgett structures: application to relative air-humidity sensing

    NASA Astrophysics Data System (ADS)

    Papkovsky, Dmitry B.; Ponomarev, Gely V.; Chernov, Sergey F.; Kurochkin, Ilya N.

    1993-05-01

    Monomolecular thin solid films containing water-soluble Pt- and Pd-porphyrins were prepared and transferred onto solid supports. Surface active charged polymer on the basis of alkylated polyethyleneimine was used to improve extraction of the dye from aqueous solution to the interface. The solid-state materials obtained which showed intense long-decay luminescence were studied by optical methods with emphasis to luminescence quenching and lifetime measurements. The results were applied to quenched-luminescence lifetime-based sensing of relative air humidity. A corresponding fiber-optic prototype device was developed.

  14. Luminescence properties of Eu-activated alkaline and alkaline-earth silicate Na{sub 2}Ca{sub 3}Si{sub 6}O{sub 16}

    SciTech Connect

    Wang, Jing; Huang, Yanlin; Wang, Xigang; Qin, Lin; Seo, Hyo Jin

    2014-07-01

    Highlights: • A novel yellow-emitting alkaline and alkaline-earth silicate Na{sub 2}Ca{sub 3}Si{sub 6}O{sub 16}:Eu{sup 2+} was first developed. • Under excitation with UV or near UV light the silicate presents broad emission band centered at 580 nm. - Abstract: Yellow-emitting phosphors of Na{sub 2}Ca{sub 3}Si{sub 6}O{sub 16}:Eu{sup 2+} was prepared by wet chemistry sol–gel method. X-ray powder diffraction and SEM measurements were applied to characterize the structure and morphology, respectively. The luminescence properties were investigated by the photoluminescence excitation and emission spectra, decay curve (lifetimes), CIE coordinates and the internal quantum efficiencies. The excitation spectra can match well with the emission light of near UV-LED chips (360–400 nm). Na{sub 2}Ca{sub 3}Si{sub 6}O{sub 16}:Eu{sup 2+} presents a symmetric emission band from 4f{sup 6}5d{sup 1} ⟶ 4f{sup 7}({sup 8}S{sub 7/2}) transitions of Eu{sup 2+} ions on doping below 3.0 mol%. On increasing Eu-doping levels, the sample contains two kinds of emission centers, i.e., Eu{sup 2+} and Eu{sup 3+} ions, which present the characteristic broad band (5d ⟶ 4f) and narrower (4f ⟶ 4f) luminescence lines, respectively. The energy transfer, the luminescence thermal stability (activation energy ΔE for thermal quenching) and luminescence mechanism of Na{sub 2}Ca{sub 3}Si{sub 6}O{sub 16}:Eu{sup 2+} phosphors were discussed by analyzing the relationship between the luminescence characteristics and the crystal structure.

  15. Structural, vibrational and luminescence properties of the (1−x)CaWO{sub 4}−xCdWO{sub 4} system

    SciTech Connect

    Taoufyq, A.; Guinneton, F.; Valmalette, J-C.; Arab, M.; Benlhachemi, A.; Bakiz, B.; Villain, S.; and others

    2014-11-15

    In the present work, we investigate the structural, microstructural, vibrational and luminescence properties of the system (1−x)CaWO{sub 4}−xCdWO{sub 4} with x ranging between 0 and 1. Polycrystalline samples were elaborated using a coprecipitation technique followed by thermal treatment at 1000 °C. The samples were then characterized using X-ray diffraction, scanning electron microscopy, Raman spectroscopy and luminescence analyses. X-ray diffraction profile analyses using Rietveld method showed that two kinds of solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4} having scheelite and wolframite structures, with respectively tetragonal and monoclinic crystal cells, were observed, with a biphasic system for compositions x=0.6 and 0.7. The scanning electron microscopy experiments showed a complex evolution of morphologies and crystallite sizes as x increased. The vibration modes of Raman spectra were characteristic of composition-dependent disordered solid solutions with decreasing wavenumbers as x increased. Luminescence experiments were performed under UV-laser light irradiation. The energies of emission bands increased linearly with cadmium composition x. The integrated intensity of luminescence reached a maximum value for the substituted wolframite phase with composition x=0.8. - Graphical abstract: Luminescence on UV excitation (364.5 nm) of (1−x)CaWO{sub 4−x}CdWO{sub 4} system, elaborated from coprecipitation technique at 1000 °C, with 0luminescence intensity for the composition x=0.8. - Highlights: • Solid solutions Ca{sub 1−x}Cd{sub x}WO{sub 4} are elaborated from coprecipitation technique. • The structures of two types of solid solutions are refined using Rietveld method. • A maximum of luminescence is obtained for an intermediate composition x=0.8.

  16. Facile Template-Free Fabrication of the hollow sea cucumber-like TbF{sub 3} and luminescent properties

    SciTech Connect

    Gao, Yu; Shi, Shan; Fang, Qinghong; Yang, Feng; Xu, Zhenhe

    2014-12-15

    Graphical abstract: Hollow sea cucumber-like TbF{sub 3} has been prepared via a facile hydrothermal route. The possible growth mechanism and the luminescent properties of the as-prepared sample have been discussed. - Highlights: • TbF3 particles were prepared by a facile hydrothermal route. • TbF3 product show strong green emission. • This method may be more widely applicable in the design of other rare-earth compounds. - Abstract: Hollow sea cucumber-like TbF{sub 3} was successfully fabricated by a self-assembled hydrothermal method. The crystal structure, morphology and photoluminescence properties of the as-prepared TbF{sub 3} crystals were investigated. The results revealed that the as-prepared TbF{sub 3} sample has orthorhombic structure and composed of monodispersed 3D hollow sea cucumber-like particles. The possible formation mechanism for sea cucumber-like TbF{sub 3} is presented in detail. Additionally, the as-prepared sample possesses property of down-conversion photoluminescence. The excitation spectrum of TbF{sub 3} sample was obtained by monitoring the emission of Tb{sup 3+} at 545 nm was composed of the characteristics f–f transition lines within the Tb{sup 3+} 4f{sup 8} configuration. Under the UV light irradiation, the emission spectrum exhibited four obvious lines centered at 491, 545, 588, and 620 nm, which was corresponding to the {sup 5}D{sub 4} → {sup 7}F{sub J} (J = 6, 5, 4, 3) transitions of the Tb{sup 3+} ions in the TbF{sub 3} nanoparticles.

  17. X-ray photoelectron spectroscopy and luminescent properties of Y2O3:Bi3+ phosphor

    NASA Astrophysics Data System (ADS)

    Jafer, R. M.; Coetsee, E.; Yousif, A.; Kroon, R. E.; Ntwaeaborwa, O. M.; Swart, H. C.

    2015-03-01

    X-ray photoelectron spectroscopy (XPS) results provided proof for the blue and green emission of Bi3+ in the Y2O3:Bi3+ phosphor. The Y2O3:Bi3+ phosphor was successfully prepared by the combustion process during the investigation of down-conversion materials for Si solar cell application. The X-ray diffraction (XRD) patterns indicated that a single-phase cubic crystal structure with the Ia3 space group was formed. X-ray photoelectron spectroscopy (XPS) showed that the Bi3+ ion replaces the Y3+ ion in two different coordination sites in the Y2O3 crystal structure. The O 1s peak shows five peaks, two which correlate with the O2- ion in Y2O3 in the two different sites, two which correlate with O2- in Bi2O3 in the two different sites and the remaining peak relates to hydroxide. The Y 3d spectrum shows two peaks for the Y3+ ion in the Y2O3 structure in two different sites and the Bi 4f spectrum shows the Bi3+ ion in the two different sites in Bi2O3. The photoluminescence (PL) results showed three broad emission bands in the blue and green regions under ultraviolet excitation, which were also present for panchromatic cathodoluminescence (CL) results. These three peaks have maxima at ∼3.4, 3.0 and 2.5 eV. The PL emission ∼3.0 eV (blue emission) showed two excitation bands centered at ∼3.7 and 3.4 eV while the PL emission at ∼2.5 eV (green emission) showed a broad excitation band from ∼4 to 3.4 eV. The panchromatic CL images were obtained for selected wavelengths at (2.99 ± 0.08) eV (for blue emission) and (2.34 ± 0.06) eV (for green emission). These luminescence results correlate with the XPS results that show that there are two different Bi3+ sites in the host lattice.

  18. Comparative dose evaluations between XVI and OBI cone beam CT systems using Gafchromic XRQA2 film and nanoDot optical stimulated luminescence dosimeters

    SciTech Connect

    Giaddui, Tawfik; Cui Yunfeng; Galvin, James; Yu Yan; Xiao Ying

    2013-06-15

    Purpose: To investigate the effect of energy (kVp) and filters (no filter, half Bowtie, and full Bowtie) on the dose response curves of the Gafchromic XRQA2 film and nanoDot optical stimulated luminescence dosimeters (OSLDs) in CBCT dose fields. To measure surface and internal doses received during x-ray volume imager (XVI) (Version R4.5) and on board imager (OBI) (Version 1.5) CBCT imaging protocols using these two types of dosimeters. Methods: Gafchromic XRQA2 film and nanoDot OSLD dose response curves were generated at different kV imaging settings used by XVI (software version R4.5) and OBI (software version 1.5) CBCT systems. The settings for the XVI system were: 100 kVp/F0 (no filter), 120 kVp/F0, and 120 kVp/F1 (Bowtie filter), and for the OBI system were: 100 kVp/full fan, 125 kVp/full fan, and 125 kVp/half fan. XRQA2 film was calibrated in air to air kerma levels between 0 and 11 cGy and scanned using reflection scanning mode with the Epson Expression 10000 XL flat-bed document scanner. NanoDot OSLDs were calibrated on phantom to surface dose levels between 0 and 14 cGy and read using the inLight{sup TM} MicroStar reader. Both dosimeters were used to measure in field surface and internal doses in a male Alderson Rando Phantom. Results: Dose response curves of XRQA2 film and nanoDot OSLDs at different XVI and OBI CBCT settings were reported. For XVI system, the surface dose ranged between 0.02 cGy in head region during fast head and neck scan and 4.99 cGy in the chest region during symmetry scan. On the other hand, the internal dose ranged between 0.02 cGy in the head region during fast head and neck scan and 3.17 cGy in the chest region during chest M20 scan. The average (internal and external) dose ranged between 0.05 cGy in the head region during fast head and neck scan and 2.41 cGy in the chest region during chest M20 scan. For OBI system, the surface dose ranged between 0.19 cGy in head region during head scan and 4.55 cGy in the pelvis region during

  19. Synthesis, crystal structures, luminescence and catalytic properties of two d¹⁰ metal coordination polymers constructed from mixed ligands.

    PubMed

    Wang, Xiao-xiao; Zhang, Ming-xi; Yu, Baoyi; Van Hecke, Kristof; Cui, Guang-hua

    2015-03-15

    Two new coordination polymers [Cd(bmb)(hmph)]n (1), {[Ag(bmb)]·H2btc}n (2) (bmb=1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2hmph=homophthalic acid, H3btc=1,3,5-benzenetetracarboxylic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, XRPD and elemental analysis. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 6(6) topology. Complex 2 shows a 1D helix chain structure connected by L1 ligands, which is finally extended into a rarely 2D 4L2 supramolecular network via C-H⋯O hydrogen bond interactions. In addition, the luminescence and catalytic properties of the two complexes for the degradation of the methyl orange azo dye in a Fenton-like process were presented. The degradation efficiency of the methyl orange azo dye for 1 and 2 are 56% and 96%, respectively. PMID:25576941

  20. Luminescence and energy transfer properties of Sr3Y(PO4)3:Ce3+, Mn2+ phosphors

    NASA Astrophysics Data System (ADS)

    Lin, Jun; Hu, Yihua; Chen, Li; Wang, Zhonghua; Zhang, Shaoan

    2016-03-01

    A series of highly efficient Sr3-yY1-x(PO4)3:xCe3+,yMn2+(SYP:xCe3+, Mn2+) phosphors have been prepared via a solid state reaction. The XRD (X-ray diffraction) data, PL (photoluminescence) and PLE (photoluminescence excitation) properties and ET (energy transfer) mechanism of obtained phosphors were discussed. When prepared in air, the self-reducing process of turning Ce4+ into Ce3+ can be found in SYP:xCe3+ phosphor. A bright red light emission was presented in the Ce3+ and Mn2+ co-doping samples via the efficient ET from the sensitizer Ce3+ to Mn2+, which is ascribed to electric multipolar interaction between these two kinds of ions. The critical concentration of Ce3+ in SrY1-x(PO4)3:xCe3+ and Mn2+ in Sr3-yY1-x(PO4)3:xCe3+, yMn2+ are x=0.07 and y=0.15, respectively. In addition, the ET efficiency reach 51.6% when the luminescence intensity of Ce3+ is half of that in the absence of Mn2+ and the concentration of Mn2+ is 0.15. The emission color of the phosphors were also clarify by CIE coordinate briefly.

  1. Structural and luminescence properties of heavily doped radio-frequency-sputtered ZnTe:Cu thin films

    SciTech Connect

    El Akkad, Fikry Mathai, Maneesh

    2015-09-07

    We report on the structural and luminescence properties of ZnTe:Cu films containing Cu concentrations up to 12 at. % and prepared using rf magnetron sputtering. The lattice parameters of the various crystalline phases prevailing at different Cu concentrations (cubic, hexagonal, and orthorhombic) are calculated and compared with literature results on films prepared using other techniques. Study of the steady state photoluminescence and excitation spectra revealed the presence of three donor impurities involved in the well-known band at ∼1.70 eV (peak L) attributed to self-activated transition. One of these donors is merging partially with the conduction band and the two others have mutually overlapping density of states with maxima at 0.29 eV and 0.45 eV below the conduction band edge. Another donor that is resonant with the conduction continuum is responsible for a higher energy emission band (peak H). The density of states of this donor has a maximum at 0.57 eV above the conduction band edge for a copper concentration of 8.2 at. %. The emission peak H undergoes a blue shift and its intensity increases sharply relative to the intensity of the L peak with the increase of Cu concentration. Moreover, the H emission extends to photon energies higher than the band gap. A possible interpretation of the behaviour of the peak H in terms of recombination involving the resonant states is suggested.

  2. Synthesis, luminescence properties, and energy transfer of novel CaWO4:Eu3+, Mn2+ red phosphor

    NASA Astrophysics Data System (ADS)

    Cao, Renping; Xu, Haidong; Peng, Dedong; Jiang, Shenhua; Luo, Zhiyang; Li, Wensheng; Yu, Xiaoguang

    2015-12-01

    Novel CaWO4:Eu3+, Mn2+ red phosphor is synthesized by solid-state reaction method in air. CaWO4:Eu3+, Mn2+ phosphor with excitation 268 and 394 nm emits red light with chromaticity coordinates (x = 0.6403, y = 0.3593). The strongest emission bands peaking at ∼615 nm is attributed to 5D0 → 7F2 of Eu3+ ion. Strong excitation band peaking at ∼394 nm indicates that the phosphor may be excited by near UV (∼394 nm) chip. Emission intensity of CaWO4:Eu3+, Mn2+ phosphor with excitation 268 nm is ∼2 times stronger than that of CaWO4:Eu3+ phosphor owing to energy transfer between Eu3+ ion and Mn2+ ion. Energy transfer from WO4 2 - group and Eu3+ ion to Mn2+ ion in CaWO4:Eu3+, Mn2+ phosphor may be explained via luminescence properties. Luminous mechanism is analyzed by energy level diagrams of WO4 2 - group, Mn2+ and Eu3+ ion. The paper content is helpful to develop and research other novel phosphors.

  3. Influence of Sm{sub 2}O{sub 3} on the crystallization and luminescence properties of boroaluminosilicate glasses

    SciTech Connect

    Zhang Yan; Lu Chunhua; Sun Liyan; Xu Zhongzi Ni Yaru

    2009-01-08

    Sm{sub 2}O{sub 3}-doped SiO{sub 2}-B{sub 2}O{sub 3}-Al{sub 2}O{sub 3}-BaO glasses were prepared by melting method in order to study the influence of Sm{sub 2}O{sub 3} on the crystallization behavior and luminescence properties. Differential scanning calorimetry (DSC), X-ray diffraction (XRD) and photoluminescence (PL) spectroscopy were used to characterize the rare earth glasses and the crystalline phases after heat-treatment. The course of phase separation and devitrification of the glasses were also investigated. The results show that the thermal stability of the glasses decreases with the increase of content of Sm{sub 2}O{sub 3}. The crystalline phase changed from SmAl{sub 2.07}(B{sub 4}O{sub 10})O{sub 0.6} to SmBO{sub 3}. Divalent Sm{sup 2+} ions were detected in the crystallization product after heat-treatment. The valence transformation from Sm{sup 3+} to Sm{sup 2+} in the crystal suggests the samarium atoms entering the barium sites. The charge carried in vacancy defect induced by the substitution led to the partial reduction process. The reduction of Sm{sup 3+} ions was promoted by the increasing of Sm{sub 2}O{sub 3} content or the extending of heat-treated holding time in boroaluminosilicate glass.

  4. Structural and luminescence properties of heavily doped radio-frequency-sputtered ZnTe:Cu thin films

    NASA Astrophysics Data System (ADS)

    El Akkad, Fikry; Mathai, Maneesh

    2015-09-01

    We report on the structural and luminescence properties of ZnTe:Cu films containing Cu concentrations up to 12 at. % and prepared using rf magnetron sputtering. The lattice parameters of the various crystalline phases prevailing at different Cu concentrations (cubic, hexagonal, and orthorhombic) are calculated and compared with literature results on films prepared using other techniques. Study of the steady state photoluminescence and excitation spectra revealed the presence of three donor impurities involved in the well-known band at ˜1.70 eV (peak L) attributed to self-activated transition. One of these donors is merging partially with the conduction band and the two others have mutually overlapping density of states with maxima at 0.29 eV and 0.45 eV below the conduction band edge. Another donor that is resonant with the conduction continuum is responsible for a higher energy emission band (peak H). The density of states of this donor has a maximum at 0.57 eV above the conduction band edge for a copper concentration of 8.2 at. %. The emission peak H undergoes a blue shift and its intensity increases sharply relative to the intensity of the L peak with the increase of Cu concentration. Moreover, the H emission extends to photon energies higher than the band gap. A possible interpretation of the behaviour of the peak H in terms of recombination involving the resonant states is suggested.

  5. Ligand Symmetry Modulation for Designing Mixed-Ligand Metal-Organic Frameworks: Gas Sorption and Luminescence Sensing Properties.

    PubMed

    Chen, Di-Ming; Tian, Jia-Yue; Liu, Chun-Sen

    2016-09-01

    Herein, we report the synthesis of a new mixed-linker Zn(II)-based metal-organic framework (MOF), {[Zn2(atz)2(bpydb)](DMA)8}n (1) (atz = deprotonated 3-amino-1,2,4-triazole, bpydb = deprotonated 4,4'-(4,4'-bipyridine-2,6-diyl) dibenzoic acid, DMA = N,N-dimethylacetamide), through symmetry modulation of a triazole ligand. The desymmetrized triazole linkers not only bond to the Zn(II) ions to result in a new helical Zn-triazolate chain building unit but also lead to the formation of a highly porous framework (N2 uptake: 617 cm(3)/g; BET surface area: 2393 m(2)/g) with 1D helical channels. The adsorption properties of desolved 1 were investigated by H2, C2H2, CO2, and CH4 sorption experiments, which showed that 1 exhibited high uptake capacity for H2 at 77 K and C2H2 around room temperature. More importantly, the high C2H2 uptake capacity but low binding energy makes this MOF a promising candidate for effective C2H2 capture from C2H2/CO2 and C2H2/CH4 mixed gases with low regenerative energy cost. In addition, 1 shows potential application for the luminescence sensing of small aromatic molecules picric acid (PA) and p-xylene (PX). PMID:27494087

  6. Morphology control and luminescence properties of BaMgAl 10O 17:Eu 2+ phosphors prepared by spray pyrolysis

    NASA Astrophysics Data System (ADS)

    Zhou, Yonghui; Lin, Jun

    2005-02-01

    Starting from the aqueous solutions of metal nitrates with citric acid and polyethylene glycol (PEG) as additives, BaMgAl 10O 17:Eu 2+ (BAM:Eu 2+) phosphors were prepared by a two-step spray pyrolysis (SP) method. X-ray powder diffraction (XRD), scanning electron microscopy (SEM) and photoluminescence spectra were used to characterize the resulted BAM:Eu 2+ phosphors. The obtained BAM:Eu 2+ phosphor particles have spherical shape, submicron size (0.5-3 μm). The effects of process conditions of the spray pyrolysis, such as molecular weight and concentration of PEG, on the morphology and luminescence properties of phosphor particles were investigated. Adequate amount of PEG was necessary for obtaining spherical particles, and the optimum emission intensity could be obtained when the concentration of PEG was 0.03 g/ml in the precursor solution. Moreover, the emission intensity of the phosphors increased with increasing of metal ion concentration in the solution. Compared with the BAM:Eu 2+ phosphor prepared by citrate-gel method, spherical BAM:Eu 2+ phosphor particles showed a higher emission intensity.

  7. Synthesis, Luminescence Properties and Energy Transfer of CaZrO3:Sm3+, Bi3+ Phosphor

    NASA Astrophysics Data System (ADS)

    Cao, Renping; Han, Peng; Luo, Wenjie; Fu, Ting; Luo, Zhiyang; Liu, Pan; Chen, Zhiquan; Yu, Xiaoguang

    2016-07-01

    Novel CaZrO3:Sm3+, Bi3+ phosphor is synthesized by a solid-state reaction method in air and the crystal structures and luminescence properties are investigated. The emission spectrum with excitation 308 nm contains emission of Sm3+ and Bi3+ ions at the same time; however, it only has an emission of Sm3+ ion with excitation 408 nm. Emission intensity of CaZrO3:Sm3+ phosphor can be enhanced about four times owing to energy transfer from the Bi3+ ion to the Sm3+ ion and with the fluxing agent role of Bi3+ ion when Bi3+ ion is co-doped. The possible luminous mechanism is analyzed by energy level diagrams of Bi3+ and Sm3+ ions and the energy transfer process in CaZrO3:Sm3+, Bi3+ phosphor. The experimental results indicate that, hopefully, CaZrO3:Sm3+, Bi3+ phosphor can be used as a reddish orange phosphor candidate for white light-emitting diodes based on near an ultraviolet (~408 nm) chip.

  8. Synthesis, Luminescence Properties and Energy Transfer of CaZrO3:Sm3+, Bi3+ Phosphor

    NASA Astrophysics Data System (ADS)

    Cao, Renping; Han, Peng; Luo, Wenjie; Fu, Ting; Luo, Zhiyang; Liu, Pan; Chen, Zhiquan; Yu, Xiaoguang

    2016-04-01

    Novel CaZrO3:Sm3+, Bi3+ phosphor is synthesized by a solid-state reaction method in air and the crystal structures and luminescence properties are investigated. The emission spectrum with excitation 308 nm contains emission of Sm3+ and Bi3+ ions at the same time; however, it only has an emission of Sm3+ ion with excitation 408 nm. Emission intensity of CaZrO3:Sm3+ phosphor can be enhanced about four times owing to energy transfer from the Bi3+ ion to the Sm3+ ion and with the fluxing agent role of Bi3+ ion when Bi3+ ion is co-doped. The possible luminous mechanism is analyzed by energy level diagrams of Bi3+ and Sm3+ ions and the energy transfer process in CaZrO3:Sm3+, Bi3+ phosphor. The experimental results indicate that, hopefully, CaZrO3:Sm3+, Bi3+ phosphor can be used as a reddish orange phosphor candidate for white light-emitting diodes based on near an ultraviolet (~408 nm) chip.

  9. Two new pyridine-2,3-dicarboxylate coordination polymers prepared from zerovalent metal precursor: Syntheses, luminescent and magnetic properties

    NASA Astrophysics Data System (ADS)

    Semerci, Fatih; Yeşilel, Okan Zafer; Soylu, Mustafa Serkan; Yerli, Yusuf; Dal, Hakan

    2014-02-01

    Two new K+/Cu(II) and Zn(II) coordination polymers with pyridine-2,3-dicarboxylate (pydc), {K2[Cu(μ-pydc)2]·3H2O}n (1) and {[Zn(μ-pydc)(H2O)(4-mim)]·H2O}n (2) (4-mim=4-methylimidazole) have been synthesized from zerovalent metal and characterized by IR, EPR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. In the sandwiched 3D anionic framework of 1, pydc ligands exhibit hexadentate coordination; tridentate coordination bond with Cu(II) and tridentate ionic interaction with K+ ions. {K2[Cu(μ-pydc)2]·3H2O}n shows a rare topology consists of three dimensional (3,4,5)-connected network with the point symbol of {42.6}2{42.84}{43.6.86}2. The distorted square pyramidal geometry of 2 is completed with an nitrogen atom from 4-mim and aqua ligand to form a 1D polynuclear structure. The hydrogen bonds link the 1D chains into 3D architecture. The temperature dependent magnetic property of complex 1 has been studied. Complex 2 exhibits unusual yellow luminescence in the solid state at room temperature.

  10. Luminescent properties of blue emitting phosphor SrZn2(PO4)2:Eu2+ for white LEDs

    NASA Astrophysics Data System (ADS)

    Lu, Wei; Liu, Yu-fei; Wang, Ying; Wang, Zhi-jun; Pang, Li-bin

    2015-11-01

    Blue emitting phosphor SrZn2(PO4)2:Eu2+ is synthesized by a high temperature solid state method, and the luminescent properties are investigated. At the 330 nm radiation excitation, SrZn2(PO4)2:Eu2+ presents an emission band at 416 nm, which is assigned to the 4f65d1→4f7 transition of Eu2+ ion. The concentration quenching effect of Eu2+ in SrZn2(PO4)2 has been validated and proved to be a resonant type via a dipole-dipole interaction. The critical distance ( R c) of Eu2+ in SrZn2(PO4)2 is calculated to be 3.244 nm. The Commission International de I'Eclairage (CIE) chromaticity coordinates of SrZn2(PO4)2:Eu2+ locate at the blue region, such as (0.150, 0.072). The results indicate that the SrZn2(PO4)2:Eu2+ phosphor may have potential applications in white light emitting diodes (LEDs).

  11. Syntheses, structures and luminescent properties of a series of 3D lanthanide coordination polymers with tripodal semirigid ligand

    SciTech Connect

    Qin Junsheng; Du Dongying; Chen Lei; Sun Xiuyun; Lan Yaqian; Su Zhongmin

    2011-02-15

    Reactions of the tripodal bridging ligand 5-(4-carboxy-phenoxy)-isophthalic acid (abbreviated as H{sub 3}cpia) with lanthanide salts lead to the formation of a family of different coordination polymers, that is, [Ln(cpia)(H{sub 2}O){sub 2}]{sub n}.nH{sub 2}O (Ln=Ce (1), Pr (2), Nd (3), Sm (4), Eu (5), Gd (6), Dy (7), Er (8), Tm (9) and Y (10)) in the presence of formic acid or diethylamine, which are characterized by elemental analysis, IR spectrum, thermogravimetric analysis (TGA), XRPD spectrum and single-crystal X-ray diffraction. Compounds 1-10 are isostructural and exhibit three-dimensional microporous frameworks. Furthermore, the photoluminescent properties of 4, 5 and 7 have been studied in detail. -- Graphical abstract: Reactions of the tripodal bridging ligand (H{sub 3}cpia) with lanthanide ions lead to the formation of a series of coordination polymers in the presence of formic acid or diethylamine. Display Omitted Research Highlights: {yields} Ten new lanthanides-based coordination polymers (1-10) have been synthesized. {yields} 1-10 exhibit 3D (4,8)-connected fluorite topology networks with 1D channel parallel to the b-axis. {yields} Compounds 4, 5 and 7 exhibit characteristic luminescence of Sm{sup 3+}, Eu{sup 3+} and Dy{sup 3+} ions, respectively.

  12. Synthesis, crystal structures, luminescence and catalytic properties of two d10 metal coordination polymers constructed from mixed ligands

    NASA Astrophysics Data System (ADS)

    Wang, Xiao-xiao; Zhang, Ming-xi; Yu, Baoyi; Van Hecke, Kristof; Cui, Guang-hua

    2015-03-01

    Two new coordination polymers [Cd(bmb)(hmph)]n (1), {[Ag(bmb)]·H2btc}n (2) (bmb = 1,4-bis(2-methylbenzimidazol-1-ylmethyl)benzene, H2hmph = homophthalic acid, H3btc = 1,3,5-benzenetetracarboxylic acid) were synthesized under hydrothermal conditions and characterized by single-crystal X-ray diffraction methods, IR spectroscopy, TGA, XRPD and elemental analysis. Complex 1 features a 3D threefold interpenetrating dia array with a 4-connected 66 topology. Complex 2 shows a 1D helix chain structure connected by L1 ligands, which is finally extended into a rarely 2D 4L2 supramolecular network via C-H⋯O hydrogen bond interactions. In addition, the luminescence and catalytic properties of the two complexes for the degradation of the methyl orange azo dye in a Fenton-like process were presented. The degradation efficiency of the methyl orange azo dye for 1 and 2 are 56% and 96%, respectively.

  13. Influence of surface coating on structural, morphological and optical properties of upconversion-luminescent LaF3:Yb/Er nanoparticles

    NASA Astrophysics Data System (ADS)

    Ansari, Anees A.; Yadav, Ranvijay; Rai, S. B.

    2016-07-01

    LaF3:Yb/Er (core), LaF3:Yb/Er@LaF3 (core/shell) and LaF3:Yb/Er@LaF3@SiO2 (core/shell/SiO2) nanoparticles were synthesized using citric-acid-based complexation process. X-ray diffraction, transmission electron microscopy, energy-dispersive X-ray analysis, optical absorption, band-gap energy ( E g), Fourier transform infrared and upconversion emission spectroscopy were employed to investigate the structural, morphological and optical properties of the synthesized core and core/shell/SiO2 nanoparticles. These core/shell/SiO2 nanoparticles can be well dispersed in aqueous solvents to form clear colloidal solution. The optical band-gap energy was decreased after shell formation due to increase in the crystalline size. The growth of an inactive and porous silica layers simultaneously on the surface of luminescent core-nanoparticles resulting an increase in average crystalline size of the nanoparticles. As-prepared inert shell-coated core/shell nanoparticles show intensive upconversion-luminescence as compared to the seed-core and silica-surface-modified core/shell/SiO2 nanoparticles because luminescent ions (Yb3+ and Er3+) ions located at the particle surface were protected from the non-radiative decay arising from surface dangling bonds and capping agent. However, our study revealed that there was only a slight reduction in upconversion efficiency for the silica-modified core/shell nanoparticles, indicating that upconversion properties of the upconversion nanoparticles are largely preserved in the core/shell/SiO2 nanoparticles. Absorption and upconversion-luminescence properties were examined for future application in the development of optical devices as well as optical bioprobes.

  14. Temporal properties of inferior colliculus neurons to photonic stimulation in the cochlea

    PubMed Central

    Tan, Xiaodong; Young, Hunter; Matic, Agnella Izzo; Zirkle, Whitney; Rajguru, Suhrud; Richter, Claus-Peter

    2015-01-01

    Infrared neural stimulation (INS) may be beneficial in auditory prostheses because of its spatially selective activation of spiral ganglion neurons. However, the response properties of single auditory neurons to INS and the possible contributions of its optoacoustic effects are yet to be examined. In this study, the temporal properties of auditory neurons in the central nucleus of the inferior colliculus (ICC) of guinea pigs in response to INS were characterized. Spatial selectivity of INS was observed along the tonotopically organized ICC. Trains of laser pulses and trains of acoustic clicks were used to evoke single unit responses in ICC of normal hearing animals. In response to INS, ICC neurons showed lower limiting rates, longer latencies, and lower firing efficiencies. In deaf animals, ICC neurons could still be stimulated by INS while unresponsive to acoustic stimulation. The site and spatial selectivity of INS both likely shaped the temporal properties of ICC neurons. PMID:26311831

  15. Luminescent, dielectric, and ferroelectric properties of Pr doped Bi{sub 7}Ti{sub 4}NbO{sub 21} multifunctional ceramics

    SciTech Connect

    Zou, Hua; Hui, Xinwei; Wang, Xusheng Li, Jun; Li, Yanxia; Yao, Xi; Peng, Dengfeng

    2013-12-14

    Pr doped Bi{sub 7}Ti{sub 4}NbO{sub 21} (BTN) multifunctional ceramics were prepared by a conventional sintering technique and their luminescent, dielectric, and ferroelectric properties were investigated. The X-ray diffraction data showed that the samples were single phase, and the scanning electron microscopy image indicated that the ceramics had flake-like grains with uniform thickness. The red emission was observed under the ultraviolet and blue light excitation at room temperature. The thermal quench of luminescence was measured and the result indicated that Pr doped BTN ceramics might be potentially applied in luminescent probes and temperature sensors. With the increasing Pr{sup 3+} content, the intensity of the photoluminescence increased initially and then decreased due to concentration quenching; The Curie temperature T{sub c} was slightly shifted to the lower temperature; the ferroelectric properties was almost unchanged by doping. As a new multifunctional material, the Pr doped BTN ceramics could be used for a wide range of application, such as integrated electro-optical devices.

  16. The effect of urea:nitrate ratio on the structure and luminescence properties of YVO4:Dy3+ phosphors

    NASA Astrophysics Data System (ADS)

    Foka, K. E.; Dejene, B. F.; Swart, H. C.

    2016-01-01

    YVO4:Dy3+ phosphor has been successfully synthesised using combustion method. The dependence of the properties of YVO4:Dy3+ phosphor upon urea:nitrate concentration was investigated. The single tetragonal phase was observed by x-ray diffraction spectra. A highly crystalline YVO4:Dy3+ sample was obtained when increasing the ratio of the urea to 2. The estimated crystalline sizes from the Scherrer's formula were found to be 20, 38, 33, 30, and 27 nm for the sample prepared with the ratio of 1, 2, 2.5, 3 and 4, respectively. The formation of agglomerated particles was observed by Scanning electron microscope images and it was observed that when increasing the concentration of urea further, flake-like particles formed. The diffuse reflectance spectra of YVO4:Dy3+ with various ratios of urea indicated that the determined optical band gap was ranging from 3.3 to 2.3 eV. Luminescence properties of YVO4:Dy3+ showed that the phosphor emit yellow colour at 573 nm and blue colour at 482 nm corresponding to 4F9/2→6H13/2 and 4F9/2→6H15/2 transitions, respectively. A very weak band at 663 nm which correspond to the 4F9/2→6H11/2 transition was also observed. It was found that the Photoluminescent emission intensity increased with an increase in the ratio of urea and reached a maximum at 2 then decreased when increasing the ratio of urea further.

  17. Control of Lanthanide Coordination Environment: Synthesis, Structure, and Oxygen-Sensitive Luminescence Properties of an Eight-Coordinate Tb(III) Complex.

    PubMed

    Nakai, Hidetaka; Seo, Juncheol; Kitagawa, Kazuhiro; Goto, Takahiro; Nonaka, Kyoshiro; Matsumoto, Takahiro; Ogo, Seiji

    2016-07-01

    Coordination environment of the Tb(3+) ion in oxygen-sensitive luminescent complexes can be successfully controlled through the size of alkyl substituents on ligands {((RMe)ArOH)4cyclen} (R = tBu or Me; cyclen = 1,4,7,10-tetraazacyclododecane); a newly prepared eight-coordinate complex 1(tBu) shows higher oxygen sensitivity (KSV = 17 600) and lower luminescence quantum yield (Φ = 0.67 under N2) than those of the previously reported seven-coordinate analogues 1(Me) and [{((MeMe)ArO)3tacn}Tb(III)(THF)] (KSV = 12 600 and 8300, Φ = 0.91 and 0.91 under N2, respectively; tacn = 1,4,7-triazacyclononane; THF = tetrahydrofuran). The oxygen-sensitive mechanism is discussed on the basis of the photophysical properties of the corresponding Gd(III) complexes. PMID:27326826

  18. Sol-gel synthesis of micro and nanocrystalline BaAl2O4:Eu3+ powders and their luminescence properties

    NASA Astrophysics Data System (ADS)

    Wiglusz, R. J.; Grzyb, T.

    2013-12-01

    In this paper, we report the obtention of barium aluminate (BaAl2O4) powders doped with Eu3+ ions by the sol-gel method heat-treated at 900 and 1000 °C for 3 h. XRD patterns indicated that the powders have orthorhombic structure with a high crystallite dispersion. The powders have size at submicron scale. They are a strong red emitting materials when are irradiated by ultraviolet light (250 nm). Measured emission and excitation luminescence spectra demonstrated characteristic spectroscopic properties of Eu3+ ions. Recorded luminescence decays and emission spectra were base for calculation of Judd-Ofelt intensity parameters. A detailed analysis of calculated parameters in connection with observed structural and spectroscopic measurements has been done and described.

  19. Deep ultraviolet photoconductive and near-infrared luminescence properties of Er3+-doped β-Ga2O3 thin films

    NASA Astrophysics Data System (ADS)

    Wu, Zhenping; Bai, Gongxun; Qu, Yingyu; Guo, Daoyou; Li, Linghong; Li, Peigang; Hao, Jianhua; Tang, Weihua

    2016-05-01

    Highly oriented ( 2 ¯ 01 ) Er3+-doped β-Ga2O3 (Er:Ga2O3) thin films with different doping concentrations were grown on (0001) sapphire substrates using radio frequency magnetron sputtering. The crystal structure, optical absorption, near-infrared luminescence, and ultraviolet photoresponse properties of Er:Ga2O3 films were systematically studied. The evolution of lattice and energy band gap with increasing doping level confirms the chemical substitution of Er3+ ions into the Ga2O3 crystal lattice. The down-shifting near-infrared luminescence (˜1538 nm: ascribed to Er3+: 4I13/2-4I15/2) was observed under ultraviolet excitation. Moreover, an obvious deep ultraviolet photoresponse was also obtained in the formed thin films.

  20. Combustion synthesis and luminescence properties of yellow-emitting phosphors Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+}

    SciTech Connect

    Xia, Zhiguo; Liao, Libing; Zhang, Zepeng; Wang, Yafang

    2012-02-15

    Graphical abstract: A yellow-emitting phosphor Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+} was firstly synthesized by the solution-combustion method. The photoluminescence excitation and emission spectra, temperature dependence of luminescence intensity, and luminescence lifetime of the phosphor were investigated. Highlights: Black-Right-Pointing-Pointer Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+} phosphor was synthesized by a solution-combustion method. Black-Right-Pointing-Pointer Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+} showed an intense yellow emission band centered at 569 nm with the CIE coordinate of (0.453, 0.526). Black-Right-Pointing-Pointer The temperature dependent luminescence property and mechanism of Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+} were studied. -- Abstract: Yellow-emitting phosphor Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+} was synthesized by a solution-combustion method. The phase structure and microstructure were determined by the X-ray diffraction (XRD) and scanning electron microscope (SEM) analysis, respectively. The as-prepared Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+} phosphor absorbed near ultraviolet and blue light of 320-500 nm, and showed an intense yellow emission band centered at 569 nm with the CIE coordinate of (0.453, 0.526). The lifetime of Eu{sup 2+} ions in Ca{sub 2}BO{sub 3}Cl:Eu{sup 2+} phosphor was measured, furthermore the temperature dependent luminescence property and mechanism were studied, which also testified that the present phosphor had a promising potential for white light-emitting diodes.

  1. Two new pyridine-2,3-dicarboxylate coordination polymers prepared from zerovalent metal precursor: Syntheses, luminescent and magnetic properties

    SciTech Connect

    Semerci, Fatih; Yeşilel, Okan Zafer; Soylu, Mustafa Serkan; Yerli, Yusuf; Dal, Hakan

    2014-02-15

    Two new K{sup +}/Cu(II) and Zn(II) coordination polymers with pyridine-2,3-dicarboxylate (pydc), (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} (1) and ([Zn(µ-pydc)(H{sub 2}O)(4-mim)]·H{sub 2}O){sub n} (2) (4-mim=4-methylimidazole) have been synthesized from zerovalent metal and characterized by IR, EPR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. In the sandwiched 3D anionic framework of 1, pydc ligands exhibit hexadentate coordination; tridentate coordination bond with Cu(II) and tridentate ionic interaction with K{sup +} ions. (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} shows a rare topology consists of three dimensional (3,4,5)-connected network with the point symbol of (4{sup 2}.6){sub 2}(4{sup 2}.8{sup 4})(4{sup 3}.6.8{sup 6}){sub 2}. The distorted square pyramidal geometry of 2 is completed with an nitrogen atom from 4-mim and aqua ligand to form a 1D polynuclear structure. The hydrogen bonds link the 1D chains into 3D architecture. The temperature dependent magnetic property of complex 1 has been studied. Complex 2 exhibits unusual yellow luminescence in the solid state at room temperature. - Graphical abstract: Two new K{sup +}/Cu(II) and Zn(II) coordination polymers with pyridine-2,3-dicarboxylate (pydc), (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} (1) and ([Zn(µ-pydc)(H{sub 2}O)(4-mim)]·H{sub 2}O){sub n} (2) (4-mim=4-methylimidazole) have been synthesized from zerovalent metal and characterized by IR, EPR spectroscopy, thermal analysis and single crystal X-ray diffraction techniques. The water soluble (K{sub 2}[Cu(μ-pydc){sub 2}]·3H{sub 2}O){sub n} shows three dimensional a rare 3,4,5-connected network with the point symbol of (4{sup 2}.6){sub 2}(4{sup 2}.8{sup 4})(4{sup 3}.6.8{sup 6}){sub 2}. The temperature dependent magnetic property of complex 1 has been studied. Complex 2 exhibits unusual yellow luminescence in the solid state at room temperature. Display Omitted - Highlights: • Water

  2. Investigating the interfacial properties of electrochemically roughened platinum electrodes for neural stimulation.

    PubMed

    Weremfo, Alexander; Carter, Paul; Hibbert, D Brynn; Zhao, Chuan

    2015-03-01

    Platinum electrodes have been electrochemically roughened (roughness factors up to 430) and evaluated for use as neural stimulation electrodes. The roughened electrodes show superior interfacial properties with increasing surface roughness. The roughened electrode (fR = 250) has a charge injection limit of 1.0 mC cm(-2) (400 μs pulse width), which is superior to that of titanium nitride (0.87 mC cm(-2)) but comparable to that of carbon nanotubes (1.0-1.6 mC cm(-2)). The surface roughness can also be optimized for different neural stimulation applications based on the available charge density at a particular pulse width of stimulation. The roughened platinum electrodes demonstrated good mechanical stability under harsh ultrasonication and electrochemical stability under continuous biphasic stimulation, indicating the potential of this biological interface to be safe and stable. PMID:25669232

  3. Intercalation of Varied Sulfonates into a Layered MOC: Confinement-Caused Tunable Luminescence and Novel Properties.

    PubMed

    Wen, Yuehong; Sheng, Tianlu; Zhu, Xiaoquan; Zhang, Hao; Zhuo, Chao; Hu, Shengmin; Cao, Wenhai; Wu, Xintao

    2016-04-01

    The pores/channels of porous 3D metal-organic frameworks (MOFs) have been widely applied to incorporate gas, solvent, or organic molecules. On the contrary, the utilization of the interlamellar void of layered metal-organic complexes (MOCs) remains underappreciated, although it is more flexible and available to accommodate molecules with different sizes. In this work, diverse sulfonates have been intercalated purposely into an identical layered MOC, which constructed various novel intercalation compounds possessing fluorescent, white-light emitting, photochromic, homochiral, or nonlinear optical (NLO) properties. With the help of single-crystal X-ray diffraction, their structures and the mutual interactions between the MOC host and the sulfonate guests were characterized. The properties of the guest molecules were tuned and meanwhile some new performances were generated after confining them into the interlayer region. Such a hybrid approach provides an efficient strategy to design and prepare multifunctional materials. PMID:26919304

  4. Polythiophenes based on pyrene as pendant group: Synthesis, structural characterization and luminescent properties

    NASA Astrophysics Data System (ADS)

    González-Juárez, E.; Güizado-Rodríguez, M.; Barba, V.; Melgoza-Ramírez, M.; Rodríguez, M.; Ramos-Ortíz, G.; Maldonado, J. L.

    2016-01-01

    Novel polythiophenes (PTs) derived from 3-alkylthiophenes (R = hexyl, octyl) and a thiophene functionalized with pyrene chromophore were synthesized. A homopolymer and copolymers were obtained by using different stoichiometric ratios, and their photophysical properties were investigated. Physicochemically characterized by FT-IR, 1H NMR, UV-vis, DSC-TGA and GPC as well as fluorescence spectroscopy, the new PTs reached moderate molecular weight distributions, exhibited good thermal properties and were easily processable for depositing films of satisfactory optical quality with third-order nonlinear optical susceptibilities of approximately 10-12 esu. The new PTs showed absorption and emission bands ranging from 346 to 430 nm, and from 450 to 570 nm, respectively, with quantum yields between 0.07 and 0.25. In addition, nanoparticles were obtained from the PTs by using the mini-emulsion technique. Their spectroscopic characteristics and morphology were determined by means of UV-vis spectroscopy and SEM analysis.

  5. Local transport properties investigation by correlating hyperspectral and confocal luminescence images

    NASA Astrophysics Data System (ADS)

    El-Hajje, G.; Ory, D.; Guillemoles, J.-F.; Lombez, L.

    2016-03-01

    In the present study, we develop a contactless optical characterization tool that quantifies and maps the trapping defects density within a thin film photovoltaic device. This is achieved by probing time-resolved photoluminescence and numerically reconstructing the experimental decays under several excitation conditions. The values of defects density in different Cu(In,Ga)Se2 solar cells were extracted and linked to photovoltaic performances such as the open-circuit voltage. In the second part of the work, the authors established a micrometric map of the trapping defects density. This revealed areas within the thin film CIGS solar cell with low photovoltaic performance and high trapping defects density. This proves that the developed tool can be used to qualify and quantify the buffer layer/absorber interface properties. The final part of the work was dedicated to finding the origin of the spatial fluctuations of the thin film transport properties. To do so, we started by establishing a micrometric map of the absolute quasi-Fermi levels splitting within the same CIGS solar cell, using the hyperspectral imager. A correlation is obtained between the map of quasi-Fermi levels splitting of and the map of the trapping defects density. The latter is found to be the origin of the frequently observed spatial fluctuations of thin film materials properties.

  6. Luminescence properties and optical absorption of X ray-irradiated KBr: Ce3(+), Tb(3+) crystals.

    PubMed

    Bangaru, S; Saradha, K; Muralidharan, G

    2015-03-01

    This paper reports that KBr doubly doped with Tb(3+) and Ce(3+) were prepared by Bridgman-Stockbarger method and characterized by Optical absorption, Photoluminescence (PL), Thermoluminescence (TL), Photo stimulated emission (PSL) and TL emission, after X-ray irradiation have been observed. The optical absorption measurement indicates that F and Z3 centers are formed in the crystal during X-ray irradiation process. It was attempted to incorporate a broad band of Ce(3+) sensitizer into the narrow band emission of Tb(3+) in the KBr host without reduction of emission intensity. Co-doping of Ce(3+) ions in KBr:Tb(3+) crystal showed a broad band emission due to the d-f transition of Ce(3+) and a reduction in the intensity of emission peaks due to (5)days → (7)F6 transition of Tb(3+) when they were excited at 250 nm. These results supported that an effective energy transfer occurs from Ce(3+) to Tb(3+) in the KBr host. Co-doping Ce(3+) ions greatly intensified the excitation peak at 260 nm for the emission at 390 nm of Tb(3+) which means that more lattice defects, involved in the energy absorption and transfer to Tb(3+), are formed by the Ce(3+) co-doping. The integrated light intensity is two orders of magnitude higher as compared to the undoped samples for similar doses of irradiation and heating rate. Thermoluminescence process has been identified due to thermal mobilization of F-electrons and this causes peaks at 371 K and at 427 K, 457 K in KBr: Ce(3+), Tb(3+) crystals. The defects generated by irradiation were monitored by optical absorption and trap parameters for the TL process were calculated and presented. PMID:25585645

  7. Lanthanide coordination polymers based on multi-donor ligand containing pyridine and phthalate moieties: Structures, luminescence and magnetic properties

    SciTech Connect

    Feng, Xun; Liu, Lang; Wang, Li-Ya; Song, Hong-Liang; Qiang Shi, Zhi; Wu, Xu-Hong; Ng, Seik-Weng

    2013-10-15

    A new family of five lanthanide-organic coordination polymers incorporating multi-functional N-hetrocyclic dicarboxylate ligand, namely, [Ln{sub 2}(Hdpp){sub 2}(dpp){sub 2}]{sub n}Ln=Pr(1), Eu(2), Gd(3), Dy(4), Er(5) (H{sub 2}dpp=1-(3, 4-dicarboxyphenyl) pyridin-4-ol) have been fabricated successfully through solvothermal reaction of 1-(3,4-dicarboxyphenyl)-4-hydroxypyridin-1-ium chloride with trivalent lanthanide salts, and have been characterized systematically. The complexes 1–5 are isomorphous and isostructural. They all feature three dimensional (3D) frameworks based on the interconnection of 1D double chains composed of the binuclear moiety [Ln{sub 2}(Hdpp){sub 2}]{sup 4+} basic carboxylate as secondary building unit (SBU). The results of magnetic analysis shows the same bridging fashion of carboxylic group in this case results in the different magnetic properties occurring within lanthanide polymers. Moreover, the Eu(III) and Dy(III) complexes display characteristic luminescence emission in the visible regions. - Graphical abstract: A new family of lanthanide-organic frameworks incorporating multi-donor twisted ligand has been fabricated successfully, and has been characterized systematically. The complexes 1–5 are isostructural, and all feather three dimensional (3D) frameworks based on the interconnection of 1D double stride chains composed of the binuclear moiety [Ln{sub 2}(Hdpp){sub 2}]{sup 2+} basic carboxylate as secondary building unit (SBU). Display Omitted - Highlights: • New family of lanthanide–organic coordination polymers incorporating multifunctional N-hetrocyclic dicarboxylate ligand has been fabricated. • They have been characterized systematically. • They all feather three dimensional frameworks based on the binuclear moiety of [Ln{sub 2}(Hdpp){sub 2}]{sup 2+}. • The Eu(III) and Dy(III) analogues exhibit intense photoluminescence.

  8. Phenyl substituted Mg porphyrazines: The effect of annulation of a chalcogen-containing heterocycle on the spectral-luminescent properties

    NASA Astrophysics Data System (ADS)

    Knyukshto, V. N.; Volkovich, D. I.; Gladkov, L. L.; Kuzmitsky, V. A.; Ul-Haque, A.; Popkova, I. A.; Stuzhin, P. A.; Solovyov, K. N.

    2012-10-01

    We have performed complex experimental and theoretical investigations of the spectral-luminescent properties and electronic structure of new phthalocyanine analogs, Mg octaphenylporphyrazine and its derivatives with an annulated thiadiazole or selenadiazole ring instead of two phenyl groups. Fluorescence characteristics have been determined at 293 and 77 K: emission, excitation, and fluorescence polarization spectra; fluorescence quantum yield φ F , and lifetime τ F . Annulation of a five-membered chalcogen-containing heterocycle leads to splitting of the long-wavelength absorption band Q(0-0) and to the bathochromic shift of its longest wavelength component Q x (0-0), which increase upon passage from S to Se. At the same time, the fluorescence quantum yield φ F and lifetime τ F decrease, which is related to the intramolecular heavy-atom effect. The geometric structure of the ground state of the Mg porphyrazine molecules has been determined based on the density functional theory (DFT), and excited electronic states have been calculated with modified parametrization of the INDO/S method, INDO/Sm. Semiquantitatively, the calculated level positions of the lowest Q states and spectral shifts of Mg octaphenylporphyrazine and S-derivative agree with experimental data. For the range of the Soret band, calculated transition energies and their intensity distributions substantially depend on the dihedral angle γ between a phenyl ring and porphyrazine macrocycle. We show that, based on calculations at the angle γ = 60°, bands in the observed absorption spectra can be assigned with an accuracy of ˜2000 cm-1.

  9. Improved properties of phosphor-filled luminescent down-shifting layers: reduced scattering, optical model, and optimization for PV application

    NASA Astrophysics Data System (ADS)

    Solodovnyk, Anastasiia; Lipovšek, Benjamin; Forberich, Karen; Stern, Edda; Krč, Janez; Batentschuk, Miroslaw; Topič, Marko; Brabec, Christoph J.

    2015-12-01

    We studied the optical properties of polymer layers filled with phosphor particles in two aspects. First, we used two different polymer binders with refractive indices n = 1.46 and n = 1.61 (λ = 600 nm) to decrease Δn with the phosphor particles (n = 1.81). Second, we prepared two particle size distributions D50 = 12 μm and D50 = 19 μm. The particles were dispersed in both polymer binders in several volume concentrations and coated onto glass with thicknesses of 150 - 600 μm. We present further a newly developed optical model for simulation and optimization of such luminescent down-shifting (LDS) layers. The model is developed within the ray tracing framework of the existing optical simulator CROWM (Combined Ray Optics / Wave Optics Model), which enables simulation of standalone LDS layers as well as complete solar cells (including thick and thin layers) enhanced by the LDS layers for an improved solar spectrum harvesting. Experimental results and numerical simulations show that the layers of the higher refractive index binder with larger particles result in the highest optical transmittance in the visible light spectrum. Finally we proved that scattering of the phosphor particles in the LDS layers may increase the overall light harvesting in the solar cell. We used numerical simulations to determine optimal layer composition for application in realistic thin-film photovoltaic devices. Surprisingly LDS layers with lower measured optical transmittance are more efficient when applied onto the solar cells due to graded refractive index and efficient light scattering. Therefore, our phosphor-filled LDS layers could possibly complement other light-coupling techniques in photovoltaics.

  10. A series of coordination polymers based on a V-shaped multicarboxylate and bisimidazole ligands: Synthesis, characterization and luminescent properties

    NASA Astrophysics Data System (ADS)

    Guo, Huadong; Yan, Yongnian; Guo, Xianmin; Wang, Nan; Qi, Yanjuan

    2016-03-01

    Based on a V-shaped multicarboxylic acid and various bisimidazole ligands, six new coordination polymers, namely, [Zn4(otba) (1,4-bix)4]·3H2O (1), [Ni4(otba)2(1,4-bix)3(H2O)2]·2H2O (2), [Zn2(H2otba)2(bib) (H2O)2] (3), [Cd2(H2otba)2(bib)]·2H2O (4), [Zn3(otba)2(bidpe)2(H2O)2] (5), [Ni2(H2otba)2(bidpe)3(H2O)2]·H2O (6) (H4otba = 3,5,3‧,5‧-oxytetrabenzoic acid, 1,4-bix = 1,2-bis(imidazol-1-ylmethyl)benzene, bib = 1,4-bis(imidazol-1-yl)benzene and bidpe = 4,4'-bis(imidazol-1-yl)diphenyl ether) have been hydrothermally synthesized and structurally characterized. Compound 1 displays an uncommon hexanodal 3D 4-connected network. Compound 2 features a trinodal 3D (4, 4, 6)-connected framework. Compound 3 shows an interesting polythreaded 1D→3D species. Compound 4 exhibits a binodal 3D (3, 8)-connected network. Compound 5 displays a three-fold interpenetration of trinodal (3, 3, 4)-connected network. Compound 6 shows a five-fold interpenetration of five-connected bilayer network. The luminescent properties of compounds 1, 3, 4 and 5 were also measured.

  11. Synthesis and Luminescent Properties of Poly(9-(3-vinyl-phenyl)-phenanthrene).

    PubMed

    Yang, Garam; Lee, Hayoon; Lee, Suji; Jung, Hyocheol; Shin, Hwangyu; Lee, Jaehyun; Park, Jongwook

    2016-02-01

    Recently, interest of polymer light-emitting diode (PLED) fabricated from conjugated polymer has augmented because PLED has advantage property that is well-suited to flexible lighting and solution processed device. In this presentation, we suggest a new polymer host based on phenanthrene, poly(9-(3-Vinyl-phenyl)-phenanthrene) (PVPP). It can be easily synthesized through simple synthetic methods which are Suzuki and Wittig reactions. PVPP film can be obtained from spin coating with solution used by common solvent. It exhibited PL maximum value of 381 nm and broad PL spectrum. Energy transfer smoothly occurred when the three dopants for green, red and yellow were used in PVPP. PMID:27433663

  12. Spectroscopic, luminescent and laser properties of nanostructured CaF2:Tm materials

    NASA Astrophysics Data System (ADS)

    Lyapin, A. A.; Fedorov, P. P.; Garibin, E. A.; Malov, A. V.; Osiko, V. V.; Ryabochkina, P. A.; Ushakov, S. N.

    2013-08-01

    The laser quality transparent СаF2:Tm fluoride ceramics has been prepared by hot forming. Comparative study of absorption and emission spectra of СаF2:Tm (4 mol.% TmF3) ceramic and single crystal samples demonstrated that these materials possess almost identical spectroscopic properties. Laser oscillations of СаF2:Tm ceramics were obtained at 1898 nm under diode pumping, with the slope efficiency of 5.5%. Also, the continuous-wave (CW) laser have been obtained for СаF2:Tm single crystal at 1890 nm pumped by a diode laser was demonstrated.

  13. Luminescent properties of SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} and its luminescence improvement by incorporating A{sup +} (A=Li, Na, and K)

    SciTech Connect

    Li, Panlai Wang, Zhijun Yang, Zhiping; Guo, Qinglin

    2014-12-15

    A novel green phosphor SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} is synthesized by a high temperature solid-state method, and its luminescent property is investigated. X-ray diffraction patterns of SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} indicate a similarity crystalline phase to SrZn{sub 2}(PO{sub 4}){sub 2}. SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} shows green emission under 369 nm excitation, and the prominent luminescence in green (544 nm) due to {sup 5}D{sub 4}–{sup 7}F{sub 5} transition of Tb{sup 3+}. For the 544 nm emission, excitation spectrum has several excitation band from 200 nm to 400 nm. Emission intensity of SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} is influenced by Tb{sup 3+} concentration, and concentration quenching effect of Tb{sup 3+} in SrZn{sub 2}(PO{sub 4}){sub 2} is also observed. With incorporating A{sup +} (A=Li, Na, and K) as compensator charge, the emission intensity of SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} can be obviously enhanced. CIE color coordinates of SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} locate in the green region. The results indicate this phosphor may be a potential application in white LEDs. - Graphical abstract: SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} can produce green emission under near-UV excitation, and its luminescent properties can be improved by incorporating A{sup +} (A=Li, Na, and K). - Highlights: • SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} can produce green emission under near-UV excitation. • Concentration quenching effect of Tb{sup 3+} in SrZn{sub 2}(PO{sub 4}){sub 2} is observed. • Emission intensities of SrZn{sub 2}(PO{sub 4}){sub 2}:Tb{sup 3+} are enhanced by codoped A{sup +} (A=Li, Na, K)

  14. Structural and light up-conversion luminescence properties of Er3+-Yb3+-W6+ substituted Bi4Ti3O12

    NASA Astrophysics Data System (ADS)

    Bokolia, Renuka; Rai, Vineet K.; Chauhan, Lalita; Sreenivas, K.

    2016-05-01

    The structural and light up-conversion (UC) luminescence properties of W6+ substituted Bi3.79Er0.03Yb0.18Ti3-xWxO12 (0 ≤ x ≤ 0.10) ceramics prepared by solid state reaction method have been investigated. X-ray diffraction (XRD) confirms the formation of single phase material with orthorhombic structure. A decrease in the lattice parameters and unit cell volume is observed with increasing W content. Strong UC luminescence at 527, 548 and 662 nm is seen under an excitation of 980 nm for an optimum W content (x = 0.06) and is attributed to the transitions 2H11/2 →4I15/2, 4S3/2 →4I15/2 and 4F9/2 →4I15/2 respectively. The improved UC luminescence is ascribed to the reduced defects such as oxygen vacancies and change in the crystal field around Er3+ ions due to B-site (Ti4+) substitution with W6+ ions. Enhanced UC emission is observed for an optimum content of w6+ in the prepared composition Bi3.79Er0.03Yb0.18Ti3-xWxO12 for x = 0.06.

  15. Luminescence properties of phosphate phosphor Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+}

    SciTech Connect

    Yang, Fu; Liu, Yufeng; Tian, Xiaodong; Dong, Guoyi; Yu, Quanmao

    2015-05-15

    A series of reddish orange-emitting phosphate phosphors Ba{sub 3}Y{sub 1−x}(PO{sub 4}){sub 3}:xSm{sup 3+}(0.01≤x≤0.20) were synthesized by solid-state reaction. X-ray diffraction and photoluminescence spectra were utilized to characterize the structure and luminescence properties of as-synthesized phosphors. The optimized phosphors Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} present several excitation bands from 300 to 500 nm, and exhibit intense reddish orange-emitting properties. The energy transfer type between Sm{sup 3+} ions was confirmed as d–d interaction by using Van Uitert model. The chromatic properties of the typical sample Ba{sub 3}Y(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor have been found to have chromaticity coordinates of (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. These results indicated that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors have potential applications in the field of lighting and display due to their effective excitation in the near-ultraviolet range. - Graphical abstract: The color coordinates for 5 mol% Sm{sup 3+} doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphor were calculated to be (0.583, 0.405), which are located in reddish orange region under the excitation of 401 nm. The peaks of Ba{sub 3}Y{sub 0.95}(PO{sub 4}){sub 3}:0.05Sm{sup 3+} phosphor with the highest emission intensity at 600 nm are broader than those of Y{sub 2}O{sub 3}:Eu{sup 3+} and Y{sub 2}O{sub 2}S:Eu{sup 3+} phosphors. All these characteristics suggest that Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} phosphors are suitable for near-UV (370–410 nm) excitation and can be applicable to near UV-based WLEDs. ▪ - Highlights: • Different concentration Sm{sup 3+}-doped Ba{sub 3}Y(PO{sub 4}){sub 3} phosphors were fabricated by solid state method. • The optimized phosphors present the several excitation bands from 300 to 500 nm. • The Ba{sub 3}Y(PO{sub 4}){sub 3}:Sm{sup 3+} shows bright reddish orange

  16. Characterization and luminescence properties of CaMgSi2O6:Eu2+ blue phosphor.

    PubMed

    Chandrakar, P; Baghel, R N; Bisen, D P; Chandra, B P

    2015-11-01

    A blue CaMgSi2O6:Eu(2+) phosphor was prepared by the solid-state reaction method and the phosphor characterized in terms of crystal structure, particle size, photoluminescence (PL), thermoluminescence (TL) and mechanoluminescence (ML) properties using X-ray diffraction (XRD), transmission electron microscopy (TEM), PL spectroscopy, TLD reader and ML impact technique. The XRD result shows that phosphor is formed in a single phase and has a monoclinic structure with the space group C2/c. Furthermore, the PL excitation spectra of Eu(2+) -doped CaMgSi2 O6 phosphor showed a strong band peak at 356 nm and the PL emission spectrum has a peak at 450 nm. The depths and frequency factors of trap centers were calculated using the TL glow curve by deconvolution method in which the trap depths were found to be 0.48 and 0.61 eV. The formation of CaMgSi2O6:Eu(2+) phosphor was confirmed by Fourier transform infrared spectroscopy. The ML intensity increased linearly with the impact velocity of the piston used to deform the phosphor. It was shown that the local piezoelectricity-induced electron bombardment model is responsible for the ML emission. Finally, the optical properties of CaMgSi2O6:Eu(2+) phosphors are discussed. PMID:25665136

  17. Magnetic and luminescent properties of manganese-doped ZnSe crystals

    NASA Astrophysics Data System (ADS)

    Sirkeli, Vadim P.; Nedeoglo, Dmitrii D.; Nedeoglo, Natalia D.; Radevici, Ivan V.; Sobolevskaia, Raisa L.; Sushkevich, Konstantin D.; Lähderanta, Erkki; Lashkul, Alexander V.; Laiho, Reino; Biethan, Jens-Peter; Yilmazoglu, Oktay; Pavlidis, Dimitris; Hartnagel, Hans L.

    2012-09-01

    Magnetic and photoluminescent properties of manganese-doped ZnSe crystals with different impurity concentrations were investigated. The concentration of Mn2+ ions in ZnSe crystals has been varied from 0.01 to 0.3 at%. Magnetic and photoluminescent studies have confirmed the introduction of Mn in ZnSe crystals. It was established that Mn2+ ions are responsible for the emission bands with maximum at 616 nm and 633 nm, which correspond to 4T2→6A1 and 4T1→6A1 intracentre transitions of Mn2+ ions respectively. It was found that the concentration quenching of the photoluminescent bands is associated with Mn2+ ions, which are due to the formation of Mn-Mn clusters. Magnetic properties studies have shown that at high doping levels the manganese atoms form Mn-Mn clusters in ZnSe. From the temperature dependence of magnetic susceptibility of ZnSe:Mn crystals that follows the Curie-Weiss law, it was possible to estimate the Curie-Weiss temperature Θ(x) and the effective Mn-Mn antiferromagnetic exchange constant (J1).

  18. Excited States and Luminescent Properties of UO2F2 and Its Solvated Complexes in Aqueous Solution

    SciTech Connect

    Su, Jing; Wang, Zheming; Pan, Duoqiang; Li, Jun

    2014-07-21

    The electronic absorption and emission spectra of free UO2F2 and its water solvated complexes below 32 000 cm–1 are investigated at the levels of ab initio CASPT2 and CCSD(T) with inclusion of scalar relativistic and spin–orbit coupling effects. The influence of the water coordination on the electronic spectra of UO2F2 is explored by investigating the excited states of solvated complexes (H2O)nUO2F2 (n = 1–3). In these uranyl complexes, water coordination is found to have appreciable influence on the 3Δ (Ω = 1g) character of the luminescent state and on the electronic spectral shape. The simulated luminescence spectral curves based on the calculated spectral parameters of (H2O)nUO2F2 from CCSD(T) approach agree well with experimental spectra in aqueous solution at both near-liquid-helium temperature and room temperature. The possible luminescence spectra of free UO2F2 in gas phase are predicted on the basis of CASPT2 and CCSD(T) results, respectively, by considering three symmetric vibration modes. Finally, the effect of competition between spin–orbit coupling and ligand field repulsion on the luminescent state properties is discussed.

  19. Luminescence properties of core-shell structured SiO{sub 2}-CaMoO{sub 4}:Eu{sup 3+} phosphor

    SciTech Connect

    Ju Xiaoxia; Li Xueming; Yang Yuling; Li Wulin; Tao Chuanyi; Feng Wenlin

    2012-03-15

    Uniform SiO{sub 2}-CaMoO{sub 4}:Eu{sup 3+} red phosphor has been synthesized by sol-gel method, and its luminescence properties have been studied by fluorescence spectrometer. The structure and morphology of the SiO{sub 2}-CaMoO{sub 4}:Eu{sup 3+} red phosphor have been investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and FT-IR spectrometer. Results indicate that phosphor particles have a core-shell structure and the thickness of the SiO{sub 2}-shell is about 60 nm. In addition, the luminescent intensity of SiO{sub 2}-CaMoO{sub 4}:Eu{sup 3+} red phosphor has been greatly enhanced with respect to CaMoO{sub 4}:Eu{sup 3+} phosphor. But the lifetime {tau} value of SiO{sub 2}-coated CaMoO{sub 4}:Eu{sup 3+} is slightly smaller than that of non-coated CaMoO{sub 4}:Eu{sup 3+}. - Graphical abstract: A SiO{sub 2} nano-layer with thickness of 60 nm and good uniformity was successfully coated on the surface of CaMoO{sub 4}:Eu{sup 3+} phosphor. This coating greatly increases luminescent intensity of the phosphor. Highlights: Black-Right-Pointing-Pointer SiO{sub 2}-CaMoO{sub 4}:Eu{sup 3+} was successfully synthesized by sol-gel method. Black-Right-Pointing-Pointer The SiO{sub 2} nano-layer increases luminescent intensity of the phosphor. Black-Right-Pointing-Pointer The SiO{sub 2} nano-layer reduces fluorescence lifetime of the phosphor.

  20. A novel contrast agent with rare earth-doped up-conversion luminescence and Gd-DTPA magnetic resonance properties

    NASA Astrophysics Data System (ADS)

    Lu, Qing; Wei, Daixu; Cheng, Jiejun; Xu, Jianrong; Zhu, Jun

    2012-08-01

    The magnetic-luminescent multifunctional nanoparticles based on Gd-DTPA and NaYF4:Yb, Er were successfully synthesized by the conjugation of activated DTPA and silica-coated/surface-aminolated NaYF4:Yb, Er nanoparticles through EDC/NHS coupling chemistry. The as-prepared products were characterized by powder X-ray diffraction, transmission electron microscopy, dynamic light scattering, energy dispersive X-ray analysis, and fourier transform infrared spectrometry. The room-temperature upconversion luminescent spectra and T1-weighted maps of the obtained nanoparticles were carried out by 980 nm NIR light excitation and a 3T MR imaging scanner, respectively. The results indicated that the as-synthesized multifunctional nanoparticles with small size, highly solubility in water, and both high MR relaxivities and upconversion luminescence may have potential usage for MR imaging in future.

  1. A novel contrast agent with rare earth-doped up-conversion luminescence and Gd-DTPA magnetic resonance properties

    SciTech Connect

    Lu Qing; Wei Daixu; Cheng Jiejun; Xu Jianrong; Zhu Jun

    2012-08-15

    The magnetic-luminescent multifunctional nanoparticles based on Gd-DTPA and NaYF{sub 4}:Yb, Er were successfully synthesized by the conjugation of activated DTPA and silica-coated/surface-aminolated NaYF{sub 4}:Yb, Er nanoparticles through EDC/NHS coupling chemistry. The as-prepared products were characterized by powder X-ray diffraction, transmission electron microscopy, dynamic light scattering, energy dispersive X-ray analysis, and fourier transform infrared spectrometry. The room-temperature upconversion luminescent spectra and T{sub 1}-weighted maps of the obtained nanoparticles were carried out by 980 nm NIR light excitation and a 3T MR imaging scanner, respectively. The results indicated that the as-synthesized multifunctional nanoparticles with small size, highly solubility in water, and both high MR relaxivities and upconversion luminescence may have potential usage for MR imaging in future. - Graphical abstract: We have synthesized magnetic-luminescent multifunctional nanoparticles based on Gd-DTPA and NaYF4:Yb, Er by the conjugation of activated DTPA and silica-coated/surface-aminolated NaYF4:Yb, Er nanoparticles through EDC/NHS coupling chemistry. Highlights: Black-Right-Pointing-Pointer A novel magnetic-luminescent multifunctional nanoparticles are synthesized. Black-Right-Pointing-Pointer The nanoparticles are highly efficient for luminescence and T{sub 1}-weighted MR imaging. Black-Right-Pointing-Pointer The nanoparticles are small in size and highly solubility in water. Black-Right-Pointing-Pointer The nanoparticles hold great potential usage for future biomedical engineering.

  2. Luminescence properties of Sm{sup 3+} impurities in strontium lithium bismuth borate glasses

    SciTech Connect

    Rajesh, D.; Ratnakaram, Y. C.; Seshadri, M.; Balakrishna, A.

    2012-06-05

    In the present work, different concentrations of Sm{sup 3+}-doped strontium lithium bismuth borate glasses (SLBiB) were prepared by melt quench technique. The amorphous nature of the prepared glass samples was confirmed by X-ray diffraction and SEM analysis. Using the J-O intensity parameters, emission and decay measurements various radiative properties are studied. The nature of decay curves of {sup 4}G{sub 5/2} level for different Sm{sup 3+} ion concentrations in SLBiB glasses has been analyzed. The intensities of observed emission peaks and measured lifetimes decrease with the increase of Sm{sup 3+} ion concentration which may be due to energy transfer between excited Sm{sup 3+} ions through cross-relaxations and resonant energy channels.

  3. Synthesis and luminescence properties of pyrazolone derivatives and their terbium complexes.

    PubMed

    Xiao, Haihua; Jiang, Xi; Li, Dong; Wu, Limin; Zhang, Wu; Guo, Dongcai

    2015-08-01

    Seven novel pyrazolone derivatives were synthesized and characterized by (1) H NMR and (13) C NMR spectra, mass spectra, infrared spectra and elemental analysis. Their terbium complexes were prepared and characterized by elemental analysis, EDTA titrimetric analysis, UV/vis spectra, infrared spectra and molar conductivity, as well as thermal analysis. The fluorescence properties and fluorescence quantum yields of the complexes were investigated at room temperature. The results indicated that pyrazolone derivatives had good energy-transfer efficiency for the terbium ion. All the terbium complexes emitted green fluorescence characteristic of terbium ions, possessed strong fluorescence intensity, and showed relatively high fluorescence quantum yields. Cyclic voltammograms of the terbium complexes were studied and the highest occupied molecular orbital (HOMO) and lowest occupied molecular orbital (LUMO) energy levels of these complexes were estimated. PMID:25352448

  4. Luminescence properties of Ce 3+-Dy 3+ codoped aluminium oxide films

    NASA Astrophysics Data System (ADS)

    Martínez-Martínez, R.; Rivera, S.; Yescas-Mendoza, E.; Álvarez, E.; Falcony, C.; Caldiño, U.

    2011-06-01

    Photoluminescence properties of CeCl 3 and DyCl 3 codoped aluminium oxide films deposited by the ultrasonic spray pyrolysis technique were characterized by excitation, emission and decay time spectroscopy. When excited by ultraviolet radiation the films emit a combination of blue and yellow wavelengths through an efficient energy transfer from Ce 3+ to Dy 3+ ions (up to around 77%). From spectroscopic data it is inferred that such energy transfer is nonradiative in nature taking place between Ce 3+ and Dy 3+ clusters through a short-range interaction mechanism. In the Ce 3+ doped single film the chromaticity coordinates are in the purplish blue region, whereas that in the cerium and dysprosium codoped films the coordinates move toward the white light emission region.

  5. The Effect of Mg Doping on Structural and Luminescent Properties of Barium Strontium Titanate (BST)

    NASA Astrophysics Data System (ADS)

    Khare, A.; Chauhan, N.

    Pure and Mg doped barium strontium titanate (BST) phosphor samples are prepared by solid state reaction (SSR) method at 1300 °c. The prepared samples are characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-VIS absorption spectroscopy. The optical properties are studied in terms of mechanoluminescence (ML) and thermoluminescence (TL). The XRD results reveal perovskite structure of samples with XRD peaks corresponding to planes (100), (110), (111), (200) and (211). The SEM micrographs exhibit agglomeration of particles of different shapes. The particle size calculated using SEM and XRD data is found to lie in nano range. The ML intensity is found to depend on applied load while the TL intensity increases with increasing irradiation time.

  6. Luminescence properties of ZnO layers grown on Si-on-insulator substrates

    SciTech Connect

    Kumar, Bhupendra; Gong, Hao; Vicknesh, S.; Chua, S. J.; Tripathy, S.

    2006-10-02

    The authors report on the photoluminescence properties of polycrystalline ZnO thin films grown on compliant silicon-on-insulator (SOI) substrates by radio frequency magnetron sputtering. The ZnO thin films on SOI were characterized by micro-Raman and photoluminescence (PL) spectroscopy. The observation of E{sub 2}{sup high} optical phonon mode near 438 cm{sup -1} in the Raman spectra of the ZnO samples represents the wurtzite crystal structure. Apart from the near-band-edge free exciton (FX) transition around 3.35 eV at 77 K, the PL spectra of such ZnO films also showed a strong defect-induced violet emission peak in the range of 3.05-3.09 eV. Realization of such ZnO layers on SOI would be useful for heterointegration with SOI-based microelectronics and microelectromechanical systems.

  7. Investigation of structural, morphological, luminescent and thermal properties of combusted aluminium-based iron oxide

    NASA Astrophysics Data System (ADS)

    Shinde, S. S.; Rajpure, K. Y.

    2010-12-01

    Nanocomposites of aluminium integrated hematite α-Fe 2O 3 are synthesized by combustion route using aqueous solutions of AR grade ferric trichloride and aluminium nitrate as precursors. The influence of aluminium incorporation on to the morphology, XPS, photoluminescence and thermal properties has been investigated. The FESEM and AFM micrographs depict that the samples are compact and have homogeneously distributed grains of varying sizes (˜20-60 nm). Chemical composition and valence states of constituent elements in hematite are analyzed by XPS. In room temperature photoluminescence (PL) study, we observed strong violet emission around 436 nm without any deep-level emission and a small PL FWHM indicating that the concentrations of defects are responsible for deep-level emissions. The specific heat and thermal conductivity study shows the phonon conduction behavior is dominant. We studied interparticle interactions using complex impedance spectroscopy. We report a new potential candidate for its possible applications in optoelectronics and magnetic devices.

  8. Syntheses, structural analyses and luminescent property of four alkaline-earth coordination polymers

    SciTech Connect

    Zhang, Sheng; Qu, Xiao-Ni; Xie, Gang; Wei, Qing; Chen, San-Ping

    2014-02-15

    Four alkaline-earth coordination polymers, [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized and characterized by single-crystal X-ray diffraction. Compounds 1 and 2 afford 2D layer networks generated by one-dimensional chains containing the [Ba{sub 2}O{sub 11}N] units. Compound 3 is of 2D mixed-metal coordination network formed by one-dimensional chain units, while 4 is of a 3D heterometallic framework. Interestingly, 1 and 2 can undergo reversible SCSC structural transformation upon dehydration/rehydration of coordinated water molecules. In addition, the π–π stacking interactions dominate fluorescent properties of compounds 1 and 2. - Graphical abstract: Four new coordination polymers [Ba(Pzdc)(H{sub 2}O)]{sub n} (1), [Ba(Pzdc)]{sub n} (2), [AgSr(Pzdc)(NO{sub 3})(H{sub 2}O)]{sub n} (3), [Ag{sub 2}Ca(Pzdc){sub 2}(H{sub 2}O)]{sub n} (4) (H{sub 2}Pzdc=2, 3-pyrazinedicarboxylic acid) have been synthesized. Compounds 1–3 display 2D topology structures and compound 4 exhibits a 3D topology structure. Fortunately, 1 and 2 undergo reversible dehydration/rehydration of coordinated water molecules. Display Omitted - Highlights: • All structures are generated by 1D chains. • 1 and 2 show reversible dehydration/rehydration of coordinated water molecules. • The π–π stacking interactions dominate fluorescent properties of compounds 1 and 2.

  9. Effect of Ce concentration on luminescence properties of Gd3Ga3Al2O12:Ce nanocrystals

    NASA Astrophysics Data System (ADS)

    Singh, K. V.; Singh, J. P.; Shinde, S.; Singh, A. K.; Tyagi, M.

    2016-05-01

    Gd3Ga3Al2O12 (GGAG) polycrystalline nano-powders doped with different Ce concentrations were prepared by a co-precipitation method followed by heat treatment at 1000°C for 24 h in air and Ar ambient. Structural and morphological studies show that the synthesized powder is pure phase having nanometer (30-50 nm) particle size. Luminescence studies carried out using UV and X-ray excitations revealed a decrease in the luminescence intensity for a Ce concentration greater than 0.5 mol% due to the concentration quenching.

  10. Tb(3+)-containing supramolecular hydrogels: luminescence properties and reversible sol-gel transitions induced by external stimuli.

    PubMed

    Ma, Xinxian; Yu, Dawei; Tang, Ning; Wu, Jincai

    2014-07-14

    A dual-responsive green-light-emitting supramolecular metal hydrogel (G-gel) was prepared by the reaction of a simple hydrazide-functionalized benzimidazole ligand (L) with Tb(NO3)3. The green luminescence of gelator L is enhanced in the G-gel due to the coordination effect between L and Tb(3+). In addition, the G-gel shows different luminescence when in a semisolid state (gel) and in a solid state (xerogel). Remarkable reversible sol-gel transitions induced by temperature or pH were observed for this G-gel. PMID:24871688

  11. Preparation and characterization of bifunctional dendrimer modified Fe{sub 3}O{sub 4}/CdTe nanoparticles with both luminescent and superparamagnetic properties

    SciTech Connect

    Wang, Xiuling; Gu, Yinjun; Dong, Shuling; Zhao, Qin; Liu, Yongjian

    2015-10-15

    Highlights: • The fluorescent superparamagnetic dendrimeric Fe{sub 3}O{sub 4}/CdTe nanoparticles are synthesized in this paper. • The synthesized nanocomposites maintain excellent magnetic properties. • The synthesized nanocomposites maintain highly luminescent markers with narrow emission bands. - Abstract: Magnetic nanoparticles Fe{sub 3}O{sub 4} were prepared by hydrothermal coprecipitation of ferric and ferrous ions using NaOH. The surface modification of Fe{sub 3}O{sub 4} nanoparticle by dendrimers has rendered the nanoparticle surface with enriched amine groups which facilitated the adsorption and conjugation of thioglycolic acid (TGA) modified CdTe quantum dots to form a stable hybrid nanostructure. Three generations (first generation: G0F, second generation: G1F, third generation: G3F) of bifunctional dendrimeric Fe{sub 3}O{sub 4}/CdTe nanoparticles were successfully prepared using this technique and characterized by microscopy. The optical and magnetic properties of the dendrimeric Fe{sub 3}O{sub 4}/CdTe nanoparticle were also investigated. The microscopic study reveals 3 different sizes for 3 generations, 16 nm (G0F), 31 nm (G1F) and 47 nm (G3F). Among three generations of nanoparticles, the G1F has the best optical property with a luminescent quantum yield of 25.6% and the G0F has the best magnetic property with a saturation magnetization of 19.3 emμ/g.

  12. Electrochemical properties of titanium nitride nerve stimulation electrodes: an in vitro and in vivo study.

    PubMed

    Meijs, Suzan; Fjorback, Morten; Jensen, Carina; Sørensen, Søren; Rechendorff, Kristian; Rijkhoff, Nico J M

    2015-01-01

    The in vivo electrochemical behavior of titanium nitride (TiN) nerve stimulation electrodes was compared to their in vitro behavior for a period of 90 days. Ten electrodes were implanted in two Göttingen minipigs. Four of these were used for electrical stimulation and electrochemical measurements. Five electrodes were kept in Ringer's solution at 37.5°C, of which four were used for electrical stimulation and electrochemical measurements. The voltage transients measured in vivo were 13 times greater than in vitro at implantation and they continued to increase with time. The electrochemical properties in vivo and the tissue resistance (Rtissue) followed a similar trend with time. There was no consistent significant difference between the electrochemical properties of the in vivo and in vitro electrodes after the implanted period. The differences between the in vivo and in vitro electrodes during the implanted period show that the evaluation of electrochemical performance of implantable stimulation electrodes cannot be substituted with in vitro measurements. After the implanted period, however, the performance of the in vivo and in vitro electrodes in saline was similar. In addition, the changes observed over time during the post-implantation period regarding the electrochemical properties of the in vivo electrodes and Rtissue were similar, which indicates that these changes are due to the foreign body response to implantation. PMID:26300717

  13. Electrochemical properties of titanium nitride nerve stimulation electrodes: an in vitro and in vivo study

    PubMed Central

    Meijs, Suzan; Fjorback, Morten; Jensen, Carina; Sørensen, Søren; Rechendorff, Kristian; Rijkhoff, Nico J. M.

    2015-01-01

    The in vivo electrochemical behavior of titanium nitride (TiN) nerve stimulation electrodes was compared to their in vitro behavior for a period of 90 days. Ten electrodes were implanted in two Göttingen minipigs. Four of these were used for electrical stimulation and electrochemical measurements. Five electrodes were kept in Ringer's solution at 37.5°C, of which four were used for electrical stimulation and electrochemical measurements. The voltage transients measured in vivo were 13 times greater than in vitro at implantation and they continued to increase with time. The electrochemical properties in vivo and the tissue resistance (Rtissue) followed a similar trend with time. There was no consistent significant difference between the electrochemical properties of the in vivo and in vitro electrodes after the implanted period. The differences between the in vivo and in vitro electrodes during the implanted period show that the evaluation of electrochemical performance of implantable stimulation electrodes cannot be substituted with in vitro measurements. After the implanted period, however, the performance of the in vivo and in vitro electrodes in saline was similar. In addition, the changes observed over time during the post-implantation period regarding the electrochemical properties of the in vivo electrodes and Rtissue were similar, which indicates that these changes are due to the foreign body response to implantation. PMID:26300717

  14. Magnetic and upconverted luminescent properties of multifunctional lanthanide doped cubic KGdF4 nanocrystals.

    PubMed

    Yang, L W; Zhang, Y Y; Li, J J; Li, Y; Zhong, J X; Chu, Paul K

    2010-12-01

    Lanthanide (Ln3+) doped KGdF4 (Ln=Yb3+, Er3+, Ho3+, Tm3+) nanocrystals with a mean diameter of approximately 12 nm were synthesized by a hydrothermal method using oleic acid as a stabilizing agent at 180 °C. The nanocrystals crystallize in the cubic phase as α-NaGdF4. When excited by a 980 nm laser, these Ln3+ doped nanocrystals exhibit multicolor up-conversion (UC) emissions in red, yellow, blue and white. The calculated color coordinates demonstrate that white UC emission (CIE-X=0.352, CIE-Y=0.347) can be obtained by varying the dopant concentrations in the Yb3+/Ho3+/Tm3+ triply-doped nanocrystals to yield different RGB emission intensities. The measured field dependence of magnetization (M-H curves) of the KGdF4 nanocrystals shows their paramagnetic characteristics that can be ascribed to the non-interacting localized nature of the magnetic moment of Gd3+ ions. Moreover, low temperature thermal treatment can enhance UC properties, magnetization and magnetic mass susceptibility of Ln3+ doped KGdF4 nanocrystals. The multifunctional Ln3+ doped KGdF4 nanocrystals have potential applications in color displays, bioseparation, and optical-magnetic dual modal nanoprobes in biomedical imaging. PMID:20877853

  15. Rapid synthesis and luminescence properties of Sr3SiO5:Eu2+ phosphors

    NASA Astrophysics Data System (ADS)

    Sun, Jiacheng; Mi, Xiaoyun; Ma, Jing; Su, Jiangang; Xia, Wei; Zhang, Lei; Bai, Zhaohui; Zhang, Xiyan

    2016-03-01

    Sr3SiO5:Eu2+ phosphors were synthesized rapidly through a microwave sintering method with the presence of activated carbon powder. The detailed composition and morphology were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The influences of sintering time, fluxing agent (BaF2) content and rare earth ion doping concentration on its photoluminescence (PL) properties were also investigated. It was clear in PL spectra that a broad emission band peaking at 570nm was obtained in as-prepared phosphors under a blue light excitation. Meanwhile, non-radiative transitions between Eu2+ ions in the Sr3SiO5 host had also been demonstrated to be attributable to dipole-dipole interactions, and the critical distance calculated by the quenching concentration was estimated to be 10.56 Å. The samples were uniform in diameter and regular in morphology. In other words, the Sr3SiO5:Eu2+ phosphors possessed a potential application for white light emitting diodes (LEDs).

  16. Preparation and Luminescent Properties of Sm3+-Doped High Thermal Stable Sodium Yttrium Orthosilicate Phosphor.

    PubMed

    Xue, Na; Hei, Zhoufei; Zhao, Ze; Wang, Jing; Wang, Ting; Li, Mengxue; Noh, Hyeon Mi; Jeong, Jung Hyun; Yu, Ruijin

    2016-04-01

    Orange-red-emitting sodium yttrium orthosilicate NaYSiO4:xSm3+ (x = 0.005, 0.01, 0.02, 0.05, 0.10, 0.15, and 0.20) were synthesized. The phase structure and photoluminescence properties of these phosphors were investigated. The emission spectrum obtained by excitation into 406 nm contains exclusively the characteristic emissions of Sm3+ at 571 nm, 602 nm, 648 nm, and 710 nm, which correspond to the transitions from 4G5/2 to 6H5/2, 6H7/2, 6H9/2, and 6H11/2 of Sm3+, respectively. The strongest one is located at 602 nm due to the 4G5/2 --> 6H7/2 transition of Sm3+, generating bright orange-red light. The optimum dopant concentration of Sm3+ ions in NaYSiO4:xSm3+ is around 2 mol%, and the critical transfer distance of Sm3+ is calculated as 23 Å. The thermal quenching temperature is above 500 K. The fluorescence lifetime of Sm3+ in NaYSiO4:0.02Sm3+ is 1.83 ms. The NaYSiO4:Sm3+ phosphors may be potentially used as red phosphors for white light emitting diodes. PMID:27451656

  17. Effect of lead fluoride incorporation on the structure and luminescence properties of tungsten sodium phosphate glasses

    NASA Astrophysics Data System (ADS)

    Nardi, Rachel Prado Russo Delorenzo; Braz, Celso Eduardo; de Camargo, Andrea S. S.; Ribeiro, Sidney J. L.; Rocha, Lucas A.; Cassanjes, Fábia Castro; Poirier, Gael

    2015-11-01

    Tungsten phosphate glasses are known to be promising materials for several applications in optics such as non linear optical properties, lower phonon energy or photochromic effects related with tungsten oxide incorporation inside the phosphate network. In this study, lead fluoride has been incorporated in a 60NaPO3-40WO3 glass composition according to the ternary molar compositions (100 - x)[0.6NaPO3-0.4WO3]-xPbF2 with x varying from 0 to 60 mol%. The structural changes as a function of composition were investigated by thermal analysis, UV-visible absorption, Raman spectroscopy, X-ray diffraction of the crystallized samples, and Eu3+ emission in the visible. While DSC analyzes points out a strong decrease in the glass network connectivity and higher crystallization tendency with increasing PbF2 contents, Raman spectra clearly identify a progressive incorporation of PbF2 in the phosphate network with the formation of terminal Psbnd F and Wsbnd F bonds. These results are also in agreement with the crystallization of β-PbF2 observed for the most lead fluoride concentrated samples. Investigation of Eu3+ emission data in the visible showed longer 5D0 excited state lifetime values and higher quantum efficiencies. These results are discussed in terms of the assumption of higher local symmetry around Eu3+ with increasing PbF2 contents.

  18. Tin-doped rutile titanium dioxide nanowires: luminescence, gas sensor, and field emission properties.

    PubMed

    Wu, Jyh Ming

    2012-02-01

    Sn-doped rutile TiO2 nanowires were synthesized by a thermal reactive evaporation route. Field emission scanning electron microscopy (FESEM) imaging reveals that the Sn-doped TiO2 nanowires exhibited diameters of 80-150 nm and 2-3 microns in length. High-resolution transmission electron microscopy (HRTEM) imaging makes it possible to observe that Sn-doped TiO2 nanowires show a certain lattices fringe of approximately 0.32 nm, which demonstrates that the nanowires are single crystalline with rutile structure and grow along the [110] axis. Cathodoluminescence (CL) reflected that on the surface of Sn-doped TiO2 nanowires, many oxygen vacancies and defect states were formed during the crystal growth. These defect states raised a broad emission peak around the red-orange band. The ethanol sensing properties of Sn-doped rutile TiO2 nanowires at a temperature of 190 degrees C for the ethanol concentrations of 50, 100, 150, 200, 400, 500, and 600 ppm, correspond to the sensor' sensitivity of 7, 12, 18, 19, 23, and 26%, respectively. The sensitivity increased with an increase in the ethanol concentration. As-synthesized TiO2 nanowires revealed a turn-on field, approximately 5.1 V/microm, at a current density of 1 microAcm(-2). PMID:22629973

  19. Luminescence properties of ZnS:Cu, Eu semiconductor nanocrystals synthesized by a hydrothermal process

    NASA Astrophysics Data System (ADS)

    Xin, Mei; Hu, Li-Zhong

    2013-08-01

    ZnS:Cu, Eu nanocrystals with an average diameter of ~ 80 nm are synthesized using a hydrothermal approach at 200 °C. The photoluminescence (PL) properties of the ZnS:Cu, Eu nanocrystals before and after annealing, as well as the doping form of Eu, are studied. The as-synthesized samples are characterized by X-ray diffraction, scanning electron microscopy, inductively coupled plasma-atomic emission spectrometry, and the excitation and emission spectra (PL). The results show that both Cu and Eu are indeed incorporated into the ZnS matrix. Compared with the PL spectrum of the Cu mono-doped sample, the PL emission intensity of the Cu and Eu-codoped sample increases and a peak appears at 516 nm, indicating that Eu3+ ions, which act as an impurity compensator and activator, are incorporated into the ZnS matrix, forming a donor level. Compared with the unannealed sample, the annealed one has an increased PL emission intensity and the peak position has a blue shift of 56 nm from 516 nm to 460 nm, which means that Eu3+ ions reduce to Eu2+ ions, thereby leading to the appearance of Eu2+ characteristic emission and generating effective host-to-Eu2+ energy transfer. The results indicate the potential applications of ZnS:Cu, Eu nanoparticles in optoelectronic devices.

  20. Hollow GdPO4:Eu3+ microspheres: Luminescent properties and applications as drug carrier

    NASA Astrophysics Data System (ADS)

    Tang, Yanxia; Mei, Rui; Yang, Shaokun; Tang, Hongxia; Yin, Wenzhong; Xu, Yongchun; Gao, Yaping

    2016-04-01

    GdPO4:Eu3+ samples were synthesized by a hydrothermal process using melamine formaldehyde (MF) as template. The X-ray diffraction (XRD) patterns and the Fourier Transform Infrared (FTIR) spectrum suggested that GdPO4:Eu3+ has a hexagonal phase. The scanning electron microscope (SEM) and transmission electron microscope (TEM) images showed that the obtained GdPO4:Eu3+ are hollow microspheres with diameters in the range of 1-1.5 μm. Under the excitation at 245 nm, hexagonal GdPO4:Eu3+ hollow microspheres showed emission bands originating from the 5D0 → 7FJ (J = 1, 2, 3 and 4) transitions of Eu3+. The drug release properties of hexagonal GdPO4:Eu3+ hollow microspheres were exhibited by the doxorubicin hydrochloride (DOX) release test. The biocompatibility of hexagonal GdPO4:Eu3+ hollow microsphere was tested by the standard 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. The results indicated that hollow GdPO4:Eu3+ microspheres have potential applications in biomedicine fields.