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Sample records for highly luminescent blue

  1. Effect of High-Temperature Annealing on Yellow and Blue Luminescence of Undoped GaN

    International Nuclear Information System (INIS)

    Chai Xu-Zhao; Zhou Dong; Liu Bin; Xie Zi-Li; Han Ping; Xiu Xiang-Qian; Chen Peng; Lu Hai; Zhang Rong; Zheng You-Dou

    2015-01-01

    The effect of high-temperature annealing on the yellow and blue luminescence of the undoped GaN is investigated by photoluminescence (PL) and x-ray photoelectron spectroscopy (XPS). It is found that the band-edge emission in the GaN apparently increases, and the yellow luminescence (YL) and blue luminescence (BL) bands dramatically decrease after annealing at 700°C. At the annealing temperature higher than 900°C, the YL and BL intensities show an enhancement for the nitrogen annealed GaN. This fact should be attributed to the increment of the Ga and N vacancies in the GaN decomposition. However, the integrated PL intensity of the oxygen annealed GaN decreases at the temperature ranging from 900°C to 1000°C. This results from the capture of many photo-generated holes by high-density surface states. XPS characterization confirms that the high-density surface states mainly originate from the incorporation of oxygen atoms into GaN at the high annealing temperature, and even induces the 0.34eV increment of the upward band bending for the oxygen annealed GaN at 1000°C. (paper)

  2. Hydrothermal synthesis of highly luminescent blue-emitting ZnSe(S) quantum dots exhibiting low toxicity

    Energy Technology Data Exchange (ETDEWEB)

    Mirnajafizadeh, Fatemeh; Ramsey, Deborah; McAlpine, Shelli [School of Chemistry, University of New South Wales, Sydney, NSW 2052 (Australia); Wang, Fan; Reece, Peter [School of Physics, University of New South Wales, Sydney, NSW 2052 (Australia); Stride, John Arron, E-mail: j.stride@unsw.edu.au [School of Chemistry, University of New South Wales, Sydney, NSW 2052 (Australia); Bragg Institute, Australian Nuclear Science and Technology Organisation, PMB 1, Menai, NSW 2234 (Australia)

    2016-07-01

    Highly luminescent quantum dots (QDs) that emit in the visible spectrum are of interest to a number of imaging technologies, not least that of biological samples. One issue that hinders the application of luminescent markers in biology is the potential toxicity of the fluorophore. Here we show that hydrothermally synthesized ZnSe(S) QDs have low cytotoxicity to both human colorectal carcinoma cells (HCT-116) and human skin fibroblast cells (WS1). The QDs exhibited a high degree of crystallinity, with a strong blue photoluminescence at up to 29% quantum yield relative to 4′,6-diamidino-2-phenylindole (DAPI) without post-synthetic UV-irradiation. Confocal microscopy images obtained of HCT-116 cells after incubation with the QDs highlighted the stability of the particles in cell media. Cytotoxicity studies showed that both HCT-116 and WS1 cells retain 100% viability after treatment with the QDs at concentrations up to 0.5 g/L, which makes them of potential use in biological imaging applications. - Highlights: • Highly luminescent ZnSe(S) QDs were synthesized using a simple, one-step hydrothermal method. • The as-synthesized QDs were found to be nontoxic in the presence of biological cells. • The QDs were stable in biological media with identical emission profile to that in water.

  3. Polarization memory of blue and red luminescence from nanocrystalline porous silicon treated by high-pressure water vapor annealing

    International Nuclear Information System (INIS)

    Gelloz, B.; Koyama, H.; Koshida, N.

    2008-01-01

    The polarization memory (PM) effect in the blue and red photoluminescence (PL) of p-type porous Si (PS) treated by high-pressure water vapor annealing (HWA) has been investigated. HWA induces a significant blue PL emission at about 450 nm, together with a drastic enhancement of the red PL intensity. The polarization memory of the red emission band is anisotropic and is in agreement with emission from quantum sized Si nanocrystals, whereas that of the blue band is high and isotropic, indicating an emission mechanism related to localized states in the amorphous Si oxide surrounding the Si skeleton of the PS layer after HWA. HWA does not induce any blue emission in PS that was electrochemically oxidized (ECO) beforehand because the electrochemically grown oxide tends to prevent the formation of blue-emitting amorphous oxide upon HWA. The PM of ECO-PS at low emission energies is anisotropic, but in a direction 45 deg. rotated compared to that of PS treated by HWA. This unique behavior may be related to the electrical nature of electrochemical oxidation. HWA increases the PM of ECO-PS. This could be attributed to the enhanced passivation induced by HWA

  4. Grassy Silica Nanoribbons and Strong Blue Luminescence

    Science.gov (United States)

    Wang, Shengping; Xie, Shuang; Huang, Guowei; Guo, Hongxuan; Cho, Yujin; Chen, Jun; Fujita, Daisuke; Xu, Mingsheng

    2016-09-01

    Silicon dioxide (SiO2) is one of the key materials in many modern technological applications such as in metal oxide semiconductor transistors, photovoltaic solar cells, pollution removal, and biomedicine. We report the accidental discovery of free-standing grassy silica nanoribbons directly grown on SiO2/Si platform which is commonly used for field-effect transistors fabrication without other precursor. We investigate the formation mechanism of this novel silica nanostructure that has not been previously documented. The silica nanoribbons are flexible and can be manipulated by electron-beam. The silica nanoribbons exhibit strong blue emission at about 467 nm, together with UV and red emissions as investigated by cathodoluminescence technique. The origins of the luminescence are attributed to various defects in the silica nanoribbons; and the intensity change of the blue emission and green emission at about 550 nm is discussed in the frame of the defect density. Our study may lead to rational design of the new silica-based materials for a wide range of applications.

  5. Point defects and the blue emission in fired quartz at high doses: a comparative luminescence and EPR study

    International Nuclear Information System (INIS)

    Woda, C.; Schilles, T.; Riser, U.; Mangini, A.; Wagner, G.A.

    2002-01-01

    The dose response of the 375 deg/ C, 470 nm TL peak in fired quartz is studied by using thermoluminescence emission spectra and monochromatic glow curves. The blue emission displays a significant sensitivity increase for doses in excess of 1000 Gy, subsequent saturation at 16 kGy and a pre-dose effect over the entire dose range. Comparison with the growth of the known electron paramagnetic resonance centres and radioluminescence emission spectra indicates that the [AlO 4 ] centre is the recombination site for the blue emission, whereas the electron trap remains unknown. The sensitivity change seems to be linked to the dose-induced reduction of the [GeO 4 /Li] centre. Possible mechanisms for the observed dose response are discussed. (author)

  6. Freestanding silicon quantum dots: origin of red and blue luminescence.

    Science.gov (United States)

    Gupta, Anoop; Wiggers, Hartmut

    2011-02-04

    In this paper, we studied the behavior of silicon quantum dots (Si-QDs) after etching and surface oxidation by means of photoluminescence (PL) measurements, Fourier transform infrared spectroscopy (FTIR) and electron paramagnetic resonance spectroscopy (EPR). We observed that etching of red luminescing Si-QDs with HF acid drastically reduces the concentration of defects and significantly enhances their PL intensity together with a small shift in the emission spectrum. Additionally, we observed the emergence of blue luminescence from Si-QDs during the re-oxidation of freshly etched particles. Our results indicate that the red emission is related to the quantum confinement effect, while the blue emission from Si-QDs is related to defect states at the newly formed silicon oxide surface.

  7. Bipolar highly solid-state luminescent phenanthroimidazole derivatives as materials for blue and white organic light emitting diodes exploiting either monomer, exciplex or electroplex emission

    OpenAIRE

    Butkutė, Rita; Lygaitis, Ramūnas; Mimaitė, Viktorija; Gudeika, Dalius; Volyniuk, Dmytro; Sini, Gjergji; Gražulevičius, Juozas Vidas

    2017-01-01

    Four phenanthroimidazole-based bipolar compounds having electron-donating carbazole or diphenylamino moieties were synthesized and characterized. All compounds form glasses and exhibit high glass transition temperatures ranging from 183 to 239 °C. Solid state blue emission was detected for all synthesized compounds and quantum yields in solid state reached 0.55. Room temperature hole and electron mobilities in the layers of phenanthroimidazole derivatives reached 3.14 × 10−4 and 5.69 × 10−4 c...

  8. Tuning into blue and red luminescence in dual-phase nano-glass–ceramics

    International Nuclear Information System (INIS)

    Chen, Daqin; Wan, Zhongyi; Zhou, Yang; Zhong, Jiasong; Ding, Mingye; Yu, Hua; Lu, Hongwei; Xiang, Weidong; Ji, Zhenguo

    2015-01-01

    Highlights: • Ga 2 O 3 and YF 3 dual-phase embedded glass ceramics were fabricated. • RE 3+ and Cr 3+ dopants incorporated into YF 3 and Ga 2 O 3 lattice respectively. • Intense blue and red emissions are simultaneously achieved in the sample. • Such glass ceramics had possible application in photosynthesis of plants. - Abstract: A series of γ-Ga 2 O 3 and β-YF 3 nanocrystals embedded dual-phase glass ceramics co-doped with rare earth (Eu 3+ or Tm 3+ ) and transition metal (Cr 3+ ) activators were successfully prepared by high-temperature melt-quenching to explore blue/red luminescent materials for potential application in photosynthesis of green plants. It is experimentally verified that Eu 3+ (or Tm 3+ ) ions partitioned into the crystallized orthorhombic YF 3 nanophases, while Cr 3+ ones entered into the precipitated cubic Ga 2 O 3 nanocrystals after glass crystallization. Such spatial separation of the different active ions in the dual-phase glass ceramics can effectively suppress adverse energy transfers between rare earth and transition metal ions, resulting in their independent and efficient luminescence. As an example, it is experimentally demonstrated that both intense Tm 3+ blue and Cr 3+ deep-red emissions are easily achieved in the Tm 3+ /Cr 3+ co-doped dual-phase glass ceramics

  9. Blue-green luminescent CdZnSeS nanocrystals synthesized with activated alkyl thiol

    International Nuclear Information System (INIS)

    Xia Xing; Liu Zuli; Du Guihuan; Li Yuebin; Ma Ming; Yao Kailun

    2012-01-01

    Semiconductor nanocrystals with blue-green luminescence are potentially useful in various applications, but the preparation has not been easy compared to regular semiconductor nanocrystals with emission in the orange-red range. In this research alloyed CdZnSeS nanocrystals with luminescence covering the wavelength range from 430 to 560 nm are obtained by a one-step method with the assistance of alkyl thiol compound 1-dodecanethiol, which serves both as the sulfur source and surface ligand. The luminescence of CdZnSeS nanocrystals can be tuned from blue to green by altering the Cd:Zn molar ratio. Besides, the amount of 1-dodecanethiol in the reaction mixture can influence the emission wavelength by restricting the growth of nanocrystals. The dual control of both particle composition and size has enabled the tuning of luminescence to cover the blue-green spectral window. This research presents a convenient method to synthesize nanocrystals with tunable blue-green emission; these materials can be useful in advanced technologies such as photovoltaics, lighting and display. - Highlights: → Obtained blue-green luminescent nanocrystals by a one-step process. → Alkyl thiol used as a sulfur source and a surface stabilizer to control particle size. → Luminescence color of NCs could be easily tuned by changing their composition and particle size simultaneously.

  10. Investigation of blue luminescence in Mg-doped nonpolar a-plane GaN

    International Nuclear Information System (INIS)

    Kim, Hogyoung; Song, Keun Man

    2014-01-01

    The temperature-dependent optical characteristics of blue luminescence (BL) band in Mg-doped nonpolar a-plane GaN films were investigated using photoluminescence (PL) measurements. For the sample with the highest Cp 2 Mg/TMGa ([Mg]/[Ga]) molar ratio, the BL band was shown to have two distinct peaks, one at about 2.95 eV and the other at about 2.75 eV, which were associated with the donor–acceptor pair (DAP) transitions between the one shallow Mg acceptor level and the two different deep donor levels. In contrast, a single broad BL band was observed for all other samples. Strong potential fluctuations caused by high compensation level in the sample with the highest [Mg]/[Ga] molar ratio might localize the carriers related to the 2.75 eV band, leading to the different emission characteristics in BL band as compared to other samples. -- Highlights: • The temperature-dependent optical characteristics of blue luminescence (BL) in Mg-doped nonpolar a-plane GaN were investigated using photoluminescence (PL) measurements. • At the highest [Mg]/[Ga] molar ratio, the BL was observed to have two distinct peaks at low temperatures. • The BL was associated with the one shallow Mg acceptor level and the two different Mg-related deep donor levels. • Strong potential fluctuations caused by high compensation level might localize the carriers

  11. Investigation of blue luminescence in Mg-doped nonpolar a-plane GaN

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Hogyoung [Department of Optometry, Seoul National University of Science and Technology, Seoul 139-743 (Korea, Republic of); Song, Keun Man, E-mail: skmmec@gmail.com [Korea Advanced Nano Fab Center, Suwon, Gyeonggi 443-770 (Korea, Republic of)

    2014-01-15

    The temperature-dependent optical characteristics of blue luminescence (BL) band in Mg-doped nonpolar a-plane GaN films were investigated using photoluminescence (PL) measurements. For the sample with the highest Cp{sub 2}Mg/TMGa ([Mg]/[Ga]) molar ratio, the BL band was shown to have two distinct peaks, one at about 2.95 eV and the other at about 2.75 eV, which were associated with the donor–acceptor pair (DAP) transitions between the one shallow Mg acceptor level and the two different deep donor levels. In contrast, a single broad BL band was observed for all other samples. Strong potential fluctuations caused by high compensation level in the sample with the highest [Mg]/[Ga] molar ratio might localize the carriers related to the 2.75 eV band, leading to the different emission characteristics in BL band as compared to other samples. -- Highlights: • The temperature-dependent optical characteristics of blue luminescence (BL) in Mg-doped nonpolar a-plane GaN were investigated using photoluminescence (PL) measurements. • At the highest [Mg]/[Ga] molar ratio, the BL was observed to have two distinct peaks at low temperatures. • The BL was associated with the one shallow Mg acceptor level and the two different Mg-related deep donor levels. • Strong potential fluctuations caused by high compensation level might localize the carriers.

  12. Tuning into blue and red luminescence in dual-phase nano-glass–ceramics

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Daqin, E-mail: dqchen@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Wan, Zhongyi; Zhou, Yang; Zhong, Jiasong; Ding, Mingye; Yu, Hua; Lu, Hongwei [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China); Xiang, Weidong [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); Ji, Zhenguo, E-mail: jizg@hdu.edu.cn [College of Materials & Environmental Engineering, Hangzhou Dianzi University, Hangzhou 310018 (China)

    2015-10-05

    Highlights: • Ga{sub 2}O{sub 3} and YF{sub 3} dual-phase embedded glass ceramics were fabricated. • RE{sup 3+} and Cr{sup 3+} dopants incorporated into YF{sub 3} and Ga{sub 2}O{sub 3} lattice respectively. • Intense blue and red emissions are simultaneously achieved in the sample. • Such glass ceramics had possible application in photosynthesis of plants. - Abstract: A series of γ-Ga{sub 2}O{sub 3} and β-YF{sub 3} nanocrystals embedded dual-phase glass ceramics co-doped with rare earth (Eu{sup 3+} or Tm{sup 3+}) and transition metal (Cr{sup 3+}) activators were successfully prepared by high-temperature melt-quenching to explore blue/red luminescent materials for potential application in photosynthesis of green plants. It is experimentally verified that Eu{sup 3+} (or Tm{sup 3+}) ions partitioned into the crystallized orthorhombic YF{sub 3} nanophases, while Cr{sup 3+} ones entered into the precipitated cubic Ga{sub 2}O{sub 3} nanocrystals after glass crystallization. Such spatial separation of the different active ions in the dual-phase glass ceramics can effectively suppress adverse energy transfers between rare earth and transition metal ions, resulting in their independent and efficient luminescence. As an example, it is experimentally demonstrated that both intense Tm{sup 3+} blue and Cr{sup 3+} deep-red emissions are easily achieved in the Tm{sup 3+}/Cr{sup 3+} co-doped dual-phase glass ceramics.

  13. The origin of luminescence from di[4-(4-diphenylaminophenyl)phenyl]sulfone (DAPSF), a blue light emitter: an X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) study.

    Science.gov (United States)

    Zhang, Duo; Zhang, Hui; Zhang, Xiaohong; Sham, Tsun-Kong; Hu, Yongfeng; Sun, Xuhui

    2016-03-07

    The electronic structure and optical properties of di[4-(4-diphenylaminophenyl)phenyl]sulfone (denoted as DAPSF), a highly efficient fluorophor, have been investigated using X-ray excited optical luminescence (XEOL) and X-ray absorption near edge structure (XANES) spectroscopy at excitation energies across the C, N, O K-edges and the sulfur K-edge. The results indicate that the blue luminescence is mainly related to the sulfur functional group.

  14. Blue and green luminescence of reduced graphene oxide quantum dots

    Czech Academy of Sciences Publication Activity Database

    Štengl, Václav; Bakardjieva, Snejana; Henych, Jiří; Lang, Kamil; Kormunda, M.

    2013-01-01

    Roč. 63, november (2013), s. 537-546 ISSN 0008-6223 Institutional support: RVO:61388980 Keywords : different solvents * graphene oxides * green luminescence * intensive cavitations * N-methyl-2-pyrrolidone Subject RIV: CA - Inorganic Chemistry Impact factor: 6.160, year: 2013

  15. The spatially resolved characterisation of Egyptian blue, Han blue and Han purple by photo-induced luminescence digital imaging.

    Science.gov (United States)

    Verri, G

    2009-06-01

    The photo-induced luminescence properties of Egyptian blue, Han blue and Han purple were investigated by means of near-infrared digital imaging. These pigments emit infrared radiation when excited in the visible range. The emission can be recorded by means of a modified commercial digital camera equipped with suitable glass filters. A variety of visible light sources were investigated to test their ability to excite luminescence in the pigments. Light-emitting diodes, which do not emit stray infrared radiation, proved an excellent source for the excitation of luminescence in all three compounds. In general, the use of visible radiation emitters with low emission in the infrared range allowed the presence of the pigments to be determined and their distribution to be spatially resolved. This qualitative imaging technique can be easily applied in situ for a rapid characterisation of materials. The results were compared to those for Egyptian green and for historical and modern blue pigments. Examples of the application of the technique on polychrome works of art are presented.

  16. Fabrication of blue luminescent MoS{sub 2} quantum dots by wet grinding assisted co-solvent sonication

    Energy Technology Data Exchange (ETDEWEB)

    Ali, Junaid; Siddiqui, Ghayas Uddin [Department of Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of); Choi, Kyung Hyun, E-mail: amm@jejunu.ac.kr [Department of Mechatronics Engineering, Jeju National University, Jeju (Korea, Republic of); Jang, Yunseok [Department of Printed Electronics, Korea Institute of Machinery & Materials, Daejeon, Republic of Korea (Korea, Republic of); Lee, Kangtaek [Department of Chemical and Biomolecular Engineering, Yonsei University (Korea, Republic of)

    2016-01-15

    Molybdenum disulfide (MoS{sub 2}) belongs to transition-metal dichalcogenides (TMDs) family and has vital position among 2D materials. Here, an efficient strategy for the synthesis of zero-dimensional MoS{sub 2} quantum dots (QDs) has been represented. This strategy consists of wet grinding of pristine MoS{sub 2} in N-methyl-2-pyrrolidone (NMP) followed by sonication in NMP and 1,2-dichlorobenzene (o-DCB). The efficacy of this approach to synthesize MoS{sub 2} QDs has been reported by analyzing the as synthesized MoS{sub 2} QDs by different characterization techniques such as high resolution transmission electron microscopy, energy dispersive x-ray spectroscopy, Raman spectroscopy, photoluminescence spectroscopy, Fourier transform infrared spectroscopy and UV–vis spectroscopy. The concentration (yield) of as synthesized MoS{sub 2} QDs was found to be 7 mg mL{sup −1}. Most of the MoS{sub 2} QDs were measured around 2–5 nm in size. The as synthesized MoS{sub 2} QDs showed distinct blue luminescence upon UV excitation. - Highlights: • Synthesis of MoS{sub 2} quantum dots. • Wet grinding of MoS{sub 2} flakes for 6 h in NMP. • Ultrasonication of MoS{sub 2} in NMP and DCB. • Particle size 2–5 nm and concentration 7 mg/ml. • MoS{sub 2} QDs showed blue luminescence.

  17. High temperature luminescence of ZnSe:Yb crystals

    Directory of Open Access Journals (Sweden)

    Makhniy V. P.

    2016-05-01

    Full Text Available The problem of obtaining of effective edge luminescence with high temperature stability in the zinc selenide crystals is discussed. This task is solved by using as the dopant rare-earth element yttrium, which is introduced into the undoped ZnSe crystal by diffusion method. Doping was carried out in an evacuated to 10 -4 Torr. and a sealed quartz ampoule, in the opposite ends of which is a sample and a mixture of the crushed Yb and Se. It has been found that the diffusion coefficient of yttrium at a temperature of 1400 K is about 5⋅10 -7 cm 2/sec. It is shown that in the luminescence spectra of ZnSe:Yb samples in the temperature range 295-470 K only blue band is observed. Dependencies of parameters of this band from the excitation level are typical for the annihilation of excitons at their inelastic scattering by free carriers. The efficacy of blue radiation at 300 K is about 30% and does not fall more than twice with increasing temperature up to 470 K, indicating its high thermal stability.

  18. Decay dynamics of blue-green luminescence in meso-porous MCM-41 nanotubes

    International Nuclear Information System (INIS)

    Lee, Y.C.; Liu, Y.L.; Wang, C.K.; Shen, J.L.; Cheng, P.W.; Cheng, C.F.; Ko, C.-H.; Lin, T.Y.

    2005-01-01

    Time-resolved photoluminescence (PL) was performed to investigate the decay of blue-green luminescence in MCM-41 nanotubes. The PL decay exhibits a clear nonexponential profile, which can be fitted by a stretched exponential function. In the temperature range from 50 to 300 K the photogenerated carriers become thermally activated with a characteristic energy of 29 meV, which is an indication of the phonon-assisted nonradiative process. The temperature dependence of the lifetime of PL decay has been explained using a model based on the radiative recombination of localized carriers and the phonon-assisted nonradiative recombination

  19. Theoretical studies of boron(III) complexes for the new blue luminescent material

    International Nuclear Information System (INIS)

    Lee, Jung Eun; Choi, Gyu Chul; Rim, Byung O.; Kim, Sung Min; Park, No Gill; Ha, Yun Kyoung; Kim, Young Sik

    2004-01-01

    Boron(III) complexes, BPh 2 (2-py-aza) and Bph 2 (2-py-in), are known as blue emitting materials. In this paper, we have studied various ligand effects of boron complex on the absorption (UV) and electroluminescence (EL) peaks computationally. To obtain optical properties, TD-DFT(B3LYP) methods are used with 6-31+G(d) basis set. It was found that EL peaks of those materials are calculated at 454 and 510 nm, which are considerably consistent with experimental data. From the results, we newly proposed two materials, BPh 2 (PBI-Me) and BPh 2 (PBI-Ph), as blue luminescent materials, whose calculated EL peaks are at 456 and 480 nm, respectively. Through the calculation results, newly designed compounds showed possibility as efficient and promising emitters in EL device

  20. Blue shift in the luminescence spectra of MEH-PPV films containing ZnO nanoparticles

    International Nuclear Information System (INIS)

    Ton-That, Cuong; Phillips, Matthew R.; Nguyen, Thien-Phap

    2008-01-01

    Luminescence properties of nanocomposites consisting of ZnO nanoparticles in a conjugated polymer, poly [2-methoxy-5-(2'-ethyl hexyloxy)-phenylene vinylene] (MEH-PPV), were investigated. Photoluminescence measurements reveal a blue shift in the emission spectrum of MEH-PPV upon incorporation of ZnO nanoparticles into the polymer film while the emission is increasingly quenched with increasing ZnO concentration. In contrast, the structure of the polymer and its conjugation length are not affected by the presence of ZnO nanoparticles (up to 16 wt% ZnO) as revealed by Raman spectroscopy. The blue shift and photoluminescence quenching are explained by the separation of photogenerated electron-hole pairs at the MEH-PPV/ZnO interface and the charging of the nanoparticles

  1. Synthesis of low-oxide blue luminescent alkyl-functionalized silicon nanoparticles with no nitrogen containing surfactant

    International Nuclear Information System (INIS)

    Thomas, Jason A.; Ashby, Shane P.; Huld, Frederik; Pennycook, Timothy J.; Chao, Yimin

    2015-01-01

    Of ever growing interest in the fields of physical chemistry and materials science, silicon nanoparticles show a great deal of potential. Methods for their synthesis are, however, often hazardous, expensive or otherwise impractical. In the literature, there is a safe, fast and cheap inverse micelle-based method for the production of alkyl-functionalized blue luminescent silicon nanoparticles, which nonetheless found limitations, due to undesirable Si-alkoxy and remaining Si–H functionalization. In the following work, these problems are addressed, whereby an optimisation of the reaction mechanism encourages more desirable capping, and the introduction of alcohol is replaced by the use of anhydrous copper (II) chloride. The resulting particles, when compared with their predecessors through a myriad of spectroscopic techniques, are shown to have greatly reduced levels of ‘undesirable’ capping, with a much lower surface oxide level; whilst also maintaining long-term air stability, strong photoluminescence and high yields

  2. Synthesis of low-oxide blue luminescent alkyl-functionalized silicon nanoparticles with no nitrogen containing surfactant

    Energy Technology Data Exchange (ETDEWEB)

    Thomas, Jason A.; Ashby, Shane P.; Huld, Frederik [University of East Anglia, School of Chemistry (United Kingdom); Pennycook, Timothy J. [SuperSTEM Laboratory, STFC Daresbury Campus (United Kingdom); Chao, Yimin, E-mail: y.chao@uea.ac.uk [University of East Anglia, School of Chemistry (United Kingdom)

    2015-05-15

    Of ever growing interest in the fields of physical chemistry and materials science, silicon nanoparticles show a great deal of potential. Methods for their synthesis are, however, often hazardous, expensive or otherwise impractical. In the literature, there is a safe, fast and cheap inverse micelle-based method for the production of alkyl-functionalized blue luminescent silicon nanoparticles, which nonetheless found limitations, due to undesirable Si-alkoxy and remaining Si–H functionalization. In the following work, these problems are addressed, whereby an optimisation of the reaction mechanism encourages more desirable capping, and the introduction of alcohol is replaced by the use of anhydrous copper (II) chloride. The resulting particles, when compared with their predecessors through a myriad of spectroscopic techniques, are shown to have greatly reduced levels of ‘undesirable’ capping, with a much lower surface oxide level; whilst also maintaining long-term air stability, strong photoluminescence and high yields.

  3. Magnetic enhancement of photoluminescence from blue-luminescent graphene quantum dots

    Science.gov (United States)

    Chen, Qi; Shi, Chentian; Zhang, Chunfeng; Pu, Songyang; Wang, Rui; Wu, Xuewei; Wang, Xiaoyong; Xue, Fei; Pan, Dengyu; Xiao, Min

    2016-02-01

    Graphene quantum-dots (GQDs) have been predicted and demonstrated with fascinating optical and magnetic properties. However, the magnetic effect on the optical properties remains experimentally unexplored. Here, we conduct a magneto-photoluminescence study on the blue-luminescence GQDs at cryogenic temperatures with magnetic field up to 10 T. When the magnetic field is applied, a remarkable enhancement of photoluminescence emission has been observed together with an insignificant change in circular polarization. The results have been well explained by the scenario of magnetic-field-controlled singlet-triplet mixing in GQDs owing to the Zeeman splitting of triplet states, which is further verified by temperature-dependent experiments. This work uncovers the pivotal role of intersystem crossing in GQDs, which is instrumental for their potential applications such as light-emitting diodes, photodynamic therapy, and spintronic devices.

  4. Selective excitation of the yellow and blue luminescence in n- and p-doped Gallium Nitride

    International Nuclear Information System (INIS)

    Colton, John S.

    2000-01-01

    GaN is an interesting material: technologically very useful, but still having many unexplained features. Two such features are the broad defect-related luminescence bands: the YL of n-type GaN and the BL of Mg-doped p-type GaN. We have employed selective excitation to investigate these bands. In the case of the YL, most of the previous evidence has supported a recombination model between distant donors and acceptors, most likely a transition involving a shallow donor to a deep acceptor. Our selective excitation experiments have resolved finer structures within the YL. Our results indicate that the YL in bulk samples is related to the YL in film samples. We suggest that selectively excited YL involves recombination at DAP complexes, rather than between spatially distant DAPs (however other recombination channels, including that of distant DAPs may become significant under other excitation conditions). Characteristics of the DAP complexes within our YL model include (a) an electron localization energy of around 60-70 meV, (b) a localized phonon energy of around 40 meV, and (c) excited states of the complex at 200 and 370 meV above the ground state. In the case of the BL, the deep defect responsible for the BL is unknown, and there may not even be a deep defect involved. Also in dispute is the role of potential fluctuations in the properties of the BL. Our results have been explain in a model whereby emission is from DAPs, and significant effects are produced by doping-related potential fluctuations and disorder. Characteristics of the our model for the BL include (a) an Urbach tail, having width E 0 = 33 meV, (b) a strong electron-LO phonon coupling occurring with a Frank-Condon shift of ∼ 180 meV between excitation and emission, (c) a mobility gap at 2.8 eV, separating highly mobile states and highly localized states, and (d) PL-like behavior for excitation energies larger than 2.8 eV, having a blue-shift with increasing excitation energy caused by the increased

  5. Synthesis of high luminescent carbon nanoparticles

    Science.gov (United States)

    Gvozdyuk, Alina A.; Petrova, Polina S.; Goryacheva, Irina Y.; Sukhorukov, Gleb B.

    2017-03-01

    In this article we report an effective and simple method for synthesis of high luminescent carbon nanodots (CDs). In our work as a carbon source sodium dextran sulfate (DS) was used because it is harmless, its analogs are used in medicine as antithrombotic compounds and blood substitutes after hemorrhage. was used as a substrate We investigated the influence of temperature parameters of hydrothermal synthesis on the photoluminescence (PL) intensity and position of emission maxima. We discovered that the PL intensity can be tuned by changing of synthesis temperature and CD concentration.

  6. Luminescent sensitization and blue shift emission of Ir(ppy){sub 2}(VPHD) by copolymerization with MMA

    Energy Technology Data Exchange (ETDEWEB)

    An Baoli, E-mail: blan@staff.shu.edu.cn [Department of Chemistry, College of Science, Shanghai University, Shanghai 200444 (China); Dai Fanzeng; Zhang Yanling; Song Jian; Huang, Xiao-Di [Department of Chemistry, College of Science, Shanghai University, Shanghai 200444 (China); Xu, Jia-Qiang, E-mail: xujiaqiang@shu.edu.cn [Department of Chemistry, College of Science, Shanghai University, Shanghai 200444 (China); State Key Laboratory of Transducer Technology, Shanghai Institute of Microsystem and Information Technology, Chinese Academy of Sciences, Shanghai 200050 (China)

    2011-08-15

    Ir(ppy){sub 2}(VPHD) (ppy=2-phenyl pyridine, VPHD=6-(4-vinylphenyl)-2,4-hexanedione) was copolymerized with methyl methacrylate (MMA). The copolymer had high quantum yield of 52.3{+-}0.5% in dilute ethyl acetate solution, and the yield increased around 45% than that of the iridium monomer. The maximum emission peaks for the copolymers shifted from 515 to 489 nm while the iridium complex content was less than 0.005 mol% in the feed. The blue emission at 489 nm and the green emission at 520 nm were analyzed by Lorenz function. They are attributed to {sup 1}MLCT and {sup 3}MLCT emissions, respectively. - Highlights: > PMMA-Ir(ppy){sub 2}(VPHD) as luminescent material with high yield of 53%. > The blue color emission at 489 nm from {sup 1}MLCT in conformity with Lorenz function. > The quantum yield for the copolymer increases 45% than that of the iridium monomer. > The {sup 3}MLCT Ex. intensity versus the monomer concentration is in conformity with Boltzmann function.

  7. Two-step excitation structure changes of luminescence centers and strong tunable blue emission on surface of silica nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Lei, E-mail: nanoyang@qq.com; Jiang, Zhongcheng; Dong, Jiazhang; Zhang, Liuqian [Hunan University, College of Materials Science and Engineering (China); Pan, Anlian, E-mail: anlian.pan@gmail.com; Zhuang, Xiujuan [Hunan University, Key Laboratory for Micro-Nano Physics and Technology of Hunan Province (China)

    2015-10-15

    We report a scheme for investigating two-step stimulated structure change of luminescence centers. Amorphous silica nanospheres with uniform diameter of 9–15 nm have been synthesized by Stöber method. Strong hydroxyl-related infrared-absorption band is observed in infrared spectrum. The surface hydroxyl groups exert great influence on the luminescent behavior of silica. They provide stable and intermediate energy states to accommodate excitation electrons. The existence of these surface states reduces the energy barrier of photochemical reactions, creating conditions for two-step excitation process. By carefully examining excitation and emission process, the nearest excitation band is absent in both optical absorption spectrum and excitation spectrum. This later generated state confirms the generation of new luminescence centers as well as the existence of photochemical reactions. Stimulated by different energies, two-step excitation process impels different photochemical reactions, prompting generation of different lattice defects on surface area of silica. Thereby, tunable luminescence is achieved. After thermal treatment, strong gap excitation band appears with the disappearance of strong surface excitation band. Strong blue luminescence also disappears. The research is significance to precise introducing structural defects and controlling position of luminescence peaks.

  8. Effects of Er3+ concentration on UV/blue upconverted luminescence and a three-photon process in the cubic nanocrystalline Y2O3:Er3+

    International Nuclear Information System (INIS)

    Wang Xin; Shan Guiye; Chao Kefu; Zhang Youlin; Liu Ruilin; Feng Liyun; Zeng Qinghui; Sun Yajuan; Liu Yichun; Kong Xianggui

    2006-01-01

    Ultraviolet (UV)/blue upconverted luminescent properties of the cubic Y 2 O 3 :Er 3+ nanocrystals as a function of the erbium concentration were investigated upon 488 nm Ar + laser excitation. The remarkable decrease of upconverted emission intensity and the quenching of the 2 P 3/2 → 4 I 11/2 / 4 I 13/2 transitions were observed in the Y 2 O 3 nanocrystals with high erbium concentration. The emission spectra and the exciting power dependence of upconverted luminescent intensities reveal that the possible upconversion mechanisms are excited-state absorption (ESA) and energy transfer (ET). Moreover, a UV/violet upconverted emission spectrum of nanocrystalline Y 2 O 3 :Er 3+ upon 980 nm light excitation was also observed and a three-photon process made a contribution to this upconverted emission

  9. Investigation of blue luminescence in Mg doped AlN films

    Energy Technology Data Exchange (ETDEWEB)

    Sun, Xiliang; Xiong, Juan, E-mail: xiongjuana@163.com; Zhang, Weihai; Liu, Lei; Gu, Haoshuang, E-mail: guhsh@hubu.edu.cn

    2015-02-05

    Highlights: • AlN films doped with 0.8–4.4 at.% Mg were deposited by magnetron sputtering. • Structural and photoluminescence properties of Mg-doped AlN films were synthesized in detailed. • A broad blue band centered at 420 nm and 440 nm was observed in Mg-doped AlN films. • An enhancement of A1 (TO) mod and a slightly blue-shift of E2 (high) mode were observed. - Abstract: The Al{sub 1−x}Mg{sub x}N thin films were deposited on (1 0 0) silicon substrates by magnetron sputtering. The structural and photoluminescence properties of the films with varying Mg concentrations were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), Raman spectra and photoluminescence (PL), respectively. The results clearly showed that the Mg atoms successfully incorporated into AlN, while the crystal structure of the films was maintained. The Raman spectra of Al{sub 1−x}Mg{sub x}N films reveals the enhancement of A{sub 1} (TO) mode, a slightly blue-shift and an augment in FWHM for E{sub 2} (high) phonon mode with increasing Mg content, which can be associated with the deterioration of (0 0 2) orientation and the appearance of (1 0 0) orientation. A broad blue band centered at 420 nm and 440 nm was observed in Mg-doped AlN films. It was suggested that the transitions from the shallow donor level not only to the ground state but also to the excited states of the deep level was responsible for the broad blue emission band. This work indicates the AlN film for the application in lighting emission devices.

  10. Optical luminescence from alkyl-passivated Si nanocrystals under vacuum ultraviolet excitation: Origin and temperature dependence of the blue and orange emissions

    OpenAIRE

    Chao, Y; Houlton, A; Horrocks, BR; Hunt, MRC; Poolton, NRJ; Yang, J; Šiller, L

    2006-01-01

    The origin and stability of luminescence are critical issues for Si nanocrystals which are intended for use as biological probes. The optical luminescence of alkyl-monolayer-passivated silicon nanocrystals was studied under excitation with vacuum ultraviolet photons (5.1–23 eV). Blue and orange emission bands were observed simultaneously, but the blue band only appeared at low temperatures (8.7 eV). At 8 K, the peak wavelengths of the emission bands were 430±2 nm (blue) and 600±2 nm (orange)....

  11. Thermally and optically stimulated luminescence of early medieval blue-green glass mosaics

    Energy Technology Data Exchange (ETDEWEB)

    Galli, A. E-mail: anna.galli@mater.unimib.it; Martini, M.; Montanari, C.; Sibilia, E

    2004-12-01

    The preliminary results of a study related to luminescent mechanisms in glass mosaic tesserae are presented. The samples came from a medieval glass deposit found during archaeological excavations in the S. Lorenzo Church in Milan. Energy Dispersive X-rays Fluorescence (EDXRF) measurements were performed to obtain information on the elemental composition of the materials. Thermally Stimulated Luminescence (TSL, both conventional and wavelength resolved) and Optically Stimulated Luminescence (OSL) analyses allowed to get information about traps and luminescence centres. The observed luminescence characteristics were close to that of quartz, showing the presence of an easy to bleach trap (300 deg. C, 1.95 eV) and of a hard to bleach trap (350 deg. C, 2.20 eV); charge transfer phenomena, involving the low-temperature peaks have been observed. There is a strong indication that the easy to bleach traps are responsible for both OSL and TSL emission at 300 deg. C.

  12. Thermally and optically stimulated luminescence of early medieval blue-green glass mosaics

    International Nuclear Information System (INIS)

    Galli, A.; Martini, M.; Montanari, C.; Sibilia, E.

    2004-01-01

    The preliminary results of a study related to luminescent mechanisms in glass mosaic tesserae are presented. The samples came from a medieval glass deposit found during archaeological excavations in the S. Lorenzo Church in Milan. Energy Dispersive X-rays Fluorescence (EDXRF) measurements were performed to obtain information on the elemental composition of the materials. Thermally Stimulated Luminescence (TSL, both conventional and wavelength resolved) and Optically Stimulated Luminescence (OSL) analyses allowed to get information about traps and luminescence centres. The observed luminescence characteristics were close to that of quartz, showing the presence of an easy to bleach trap (300 deg. C, 1.95 eV) and of a hard to bleach trap (350 deg. C, 2.20 eV); charge transfer phenomena, involving the low-temperature peaks have been observed. There is a strong indication that the easy to bleach traps are responsible for both OSL and TSL emission at 300 deg. C

  13. Raman scattering and luminescence of high-Tc superconducting oxides

    International Nuclear Information System (INIS)

    Eremenko, V.V.; Gnezdilov, V.P.; Fomin, V.I.; Fugol', I.Ya.; Samovarov, V.N.

    1989-01-01

    Raman and luminescence spectra of high-T c superconducting oxides are summarized, mainly YBa 2 Cu 3 O 7-σ and partly La 2-x Ba x CuO 4-σ . In raman spectra we succeeded to distinguish electron scattering to define the energy gap Δ in the superconducting state. The luminescence spectra are due to the emission of oxygen and interaction with conduction electrons. 70 refs.; 13 figs

  14. Highly concentrated zinc oxide nanocrystals sol with strong blue emission

    International Nuclear Information System (INIS)

    Vafaee, M.; Sasani Ghamsari, M.; Radiman, S.

    2011-01-01

    Highly concentrated ZnO sol was synthesized by an improved sol-gel method. Water was used as a modifier to control the sol-gel reaction and provide a way to increase the sol concentration. Concentration of ZnO in the prepared sol is higher than from other methods. Optical absorption and photoluminescence were used to investigate optical properties of the prepared sol. FTIR test was performed to study the influence of water on the compounds of as-prepared sol. The size and morphology of ZnO nanoparticles have been studied by HRTEM. The prepared colloidal ZnO nanocrystals have narrow size distribution (5-8 nm) and showed strong blue emission. The prepared sol has enough potential for optoelectronic applications. - Research highlights: → Novel sol-gel route has been employed to prepare highly concentrated ZnO colloidal nanocrystals. → Water has been used to control the sources of emission in synthesized material. → A strong blue luminescent material has been obtained.

  15. Anti-Stokes Luminescence in High Quality Quantum Wells

    Science.gov (United States)

    Vinattieri, A.; Bogani, F.; Miotto, A.; Ceccherini, S.

    1997-11-01

    We present a detailed investigation of the anti-Stokes (AS) luminescence which originates from exciton recombination when below gap excitation is used, in a set of high quality quantum well structures. We observe strong excitonic resonances in the AS signal as measured from photoluminescence and photoluminescence excitation spectra. We demonstrate that neither the electromagnetic coupling between the wells nor the morphological disorder can explain this up-conversion effect. Time-resolved luminescence data after ps excitation and fs correlation spectroscopy results provide clear evidence of the occurrence of a two-step absorption which is assisted by the exciton population resonantly excited by the first photon.

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

    DEFF Research Database (Denmark)

    Jain, M.; Singhvi, A.K.

    2001-01-01

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

  17. Luminescent and morphological study of Sr2CeO4 blue phosphor prepared from oxalate precursors

    International Nuclear Information System (INIS)

    Ferrari, Jefferson L.; Pires, Ana M.; Serra, Osvaldo A.; Davolos, Marian R.

    2011-01-01

    Luminescent and morphological studies of Sr 2 CeO 4 blue phosphor prepared from cerium-doped strontium oxalate precursor are reported. Powder samples were prepared from 5 and 25 mol% Ce 3+ -doped strontium oxalate as well as from a mechanical mixture of strontium oxalate and cerium oxalate at a 4:1 ratio, respectively. All the samples were characterized by XRD, IR, PLS, and SEM. The luminescent and structural properties of the Sr 2 CeO 4 material are little affected by the SrCO 3 remaining from precursors. The Sr 2 CeO 4 material consists in one-dimensional chains of edge-sharing CeO 6 octahedra that are linked together by Sr 2+ ions. The carbonate ion might be associated with oxygen ions of the linear chain, and also with the oxygen atoms located in the equatorial position, which consequently affects the charge transfer bands between O 2- and Ce 4+ . As observed by SEM, the morphological changes are related to each kind of precursor and thermal treatment, along with irregular powder particles within the size range 0.5-2 μm.

  18. Luminescent properties of UV excitable blue emitting phosphors MSr4(BO3)3:Ce3+ (M = Li and Na)

    International Nuclear Information System (INIS)

    Guo Chongfeng; Ding Xu; Seo, Hyo Jin; Ren Zhaoyu; Bai Jintao

    2011-01-01

    Research highlights: → Novel blue emitting phosphors borate MSr 4 (BO 3 ) 3 (M = Li or Na) were prepared first. → Luminescent properties of phosphors borate MSr 4 (BO 3 ) 3 (M = Li or Na) were investigated extensively as candidates of blue emitting phosphor used for UV excited LED. → The optimal concentrations of dopant Ce 3+ ions in compound MSr 4 (BO 3 ) 3 (M = Li or Na) were determined as 0.05 for Li and x = 0.09 for Na excited by UV light respectively. - Abstract: A series of Ce 3+ doped novel borate phosphors MSr 4 (BO 3 ) 3 (M = Li or Na) were successfully synthesized by traditional solid-state reaction. The crystal structures and the phase purities of samples were characterized by powder X-ray diffraction. The optimal concentrations of dopant Ce 3+ ions in compound MSr 4 (BO 3 ) 3 (M = Li or Na) were determined through the measurements of photoluminescence spectra of phosphors. Ce 3+ doped phosphors MSr 4 (BO 3 ) 3 (M = Li or Na) show strong broad band absorption in UV spectral region and bright blue emission under the excitation of 345 nm light. In addition, the temperature dependences of emission spectra of M 1+x Sr 4-2x Ce x (BO 3 ) 3 (M = Li or Na) phosphors with optimal composition x = 0.05 for Li and x = 0.09 for Na excited under 355 nm pulse laser were also investigated. The experimental results indicate that the M 1+x Sr 4-2x Ce x (BO 3 ) 3 (M = Li or Na) phosphors are promising blue emitting phosphors pumped by UV light.

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

    International Nuclear Information System (INIS)

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

    2009-01-01

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

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

    DEFF Research Database (Denmark)

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

    2009-01-01

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

  1. Luminescent Lanthanide Reporters for High-Sensitivity Novel Bioassays

    Energy Technology Data Exchange (ETDEWEB)

    Anstey, Mitchell R. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Fruetel, Julia A. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Foster, Michael E. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Hayden, Carl C. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Buckley, Heather L. [Sandia National Lab. (SNL-CA), Livermore, CA (United States); Arnold, John [Sandia National Lab. (SNL-CA), Livermore, CA (United States)

    2013-09-01

    Biological imaging and assay technologies rely on fluorescent organic dyes as reporters for a number of interesting targets and processes. However, limitations of organic dyes such as small Stokes shifts, spectral overlap of emission signals with native biological fluorescence background, and photobleaching have all inhibited the development of highly sensitive assays. To overcome the limitations of organic dyes for bioassays, we propose to develop lanthanide-based luminescent dyes and demonstrate them for molecular reporting applications. This relatively new family of dyes was selected for their attractive spectral and chemical properties. Luminescence is imparted by the lanthanide atom and allows for relatively simple chemical structures that can be tailored to the application. The photophysical properties offer unique features such as narrow and non-overlapping emission bands, long luminescent lifetimes, and long wavelength emission, which enable significant sensitivity improvements over organic dyes through spectral and temporal gating of the luminescent signal.Growth in this field has been hindered due to the necessary advanced synthetic chemistry techniques and access to experts in biological assay development. Our strategy for the development of a new lanthanide-based fluorescent reporter system is based on chelation of the lanthanide metal center using absorbing chromophores. Our first strategy involves "Click" chemistry to develop 3-fold symmetric chelators and the other involves use of a new class of tetrapyrrole ligands called corroles. This two-pronged approach is geared towards the optimization of chromophores to enhance light output.

  2. Blue emitting organic semiconductors under high pressure

    DEFF Research Database (Denmark)

    Knaapila, Matti; Guha, Suchismita

    2016-01-01

    This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure and inter......This review describes essential optical and emerging structural experiments that use high GPa range hydrostatic pressure to probe physical phenomena in blue-emitting organic semiconductors including π-conjugated polyfluorene and related compounds. The work emphasizes molecular structure...... and intermolecular self-organization that typically determine transport and optical emission in π-conjugated oligomers and polymers. In this context, hydrostatic pressure through diamond anvil cells has proven to be an elegant tool to control structure and interactions without chemical intervention. This has been...... and intermolecular interactions on optical excitations, electron–phonon interaction, and changes in backbone conformations. This picture is connected to the optical high pressure studies of other π-conjugated systems and emerging x-ray scattering experiments from polyfluorenes which provides a structure-property map...

  3. Blue luminescence in Tm3+-doped KGd(WO4)2 single crystals

    International Nuclear Information System (INIS)

    Gueell, F.; Mateos, X.; Gavalda, Jna.; Sole, R.; Aguilo, M.; Diaz, F.; Massons, J.

    2004-01-01

    Up-conversion blue emissions of trivalent thulium ions in monoclinic KGd(WO 4 ) 2 single crystals at 454 and 479 nm are reported for a single pump laser source at 688 nm. We grew thulium-doped KGd(WO 4 ) 2 single crystals at several concentrations from 0.1% to 10%. We recorded a polarized optical absorption spectrum for the 3 F 2 + 3 F 3 energy levels of thulium at room temperature and low temperature (6 K). From the low temperature emission spectra we determined the splitting of the 3 H 6 ground state. The blue emissions are characterized as a function of the dopant concentration and temperature from 10 K to room temperature. To our knowledge, this is the first time that sequential two-photon excitation process (STEP) generated blue emissions in thulium-doped single crystals with a single excitation wavelength

  4. High-power pure blue laser diodes

    Energy Technology Data Exchange (ETDEWEB)

    Ohta, M.; Ohizumi, Y.; Hoshina, Y.; Tanaka, T.; Yabuki, Y.; Goto, S.; Ikeda, M. [Development Center, Sony Shiroishi Semiconductor Inc., Miyagi (Japan); Funato, K. [Materials Laboratories, Sony Corporation, Kanagawa (Japan); Tomiya, S. [Materials Analysis Laboratory, Sony Corporation, Kanagawa (Japan)

    2007-06-15

    We successfully developed high-power and long-lived pure blue laser diodes (LDs) having an emission wavelength of 440-450 nm. The pure-blue LDs were grown by metalorganic chemical vapor deposition (MOCVD) on GaN substrates. The dislocation density was successfully reduced to {proportional_to}10{sup 6} cm{sup -2} by optimizing the MOCVD growth conditions and the active layer structure. The vertical layer structure was designed to have an absorption loss of 4.9 cm{sup -1} and an internal quantum efficiency of 91%. We also reduced the operating current density to 6 kA/cm{sup 2} under 750 mW continuous-wave operation at 35 C by optimizing the stripe width to 12 {mu}m and the cavity length to 2000 {mu}m. The half lifetimes in constant current mode are estimated to be longer than 10000 h. (copyright 2007 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. C8-structured carbon quantum dots: Synthesis, blue and green double luminescence, and origins of surface defects

    Science.gov (United States)

    Xifang, Chen; Wenxia, Zhang; Qianjin, Wang; Jiyang, Fan

    Carbon quantum dots (CQDs) have attracted great attention in the past few years due to their low cytotoxicity, exploited various synthesis methods, unexampled abundance of raw materials on earth, and robust near-infrared to near-UV luminescence. Carbon nanoparticles have applications in biological labeling, delivery of drugs and biological molecules into cells, and light emitting diodes and lasing. CQDs generally exist as nanodiamonds or graphite quantum dots according to previous research reports. In this study, we report the first synthesis of the third-allotrope CQDs through carbonization of sucrose and study their luminescence properties. These CQDs have a body-centered cubic structure and each lattice point is composed of eight atoms which form a sub-cube (so called C8 crystal structure). High-resolution transmission electron microscopy and X-ray diffraction confirm the C8 structure of the synthesized carbon nanocrystallites with an average size of 2 nm. The C8 CQDs exhibit double-band luminescence with two peaks centered at around 432 and 520 nm. The study based on the photoluminescence, UV-Vis absorption, Fourier-transform infrared, and X-ray photoelectron spectroscopies reveals that the green emission originates from the C=O related surface defect.

  6. Cultivating Fluorescent Flowers with Highly Luminescent Carbon Dots Fabricated by a Double Passivation Method.

    Science.gov (United States)

    Han, Shuai; Chang, Tao; Zhao, Haiping; Du, Huanhuan; Liu, Shan; Wu, Baoshuang; Qin, Shenjun

    2017-07-07

    In this work, we present the fabrication of highly luminescent carbon dots (CDs) by a double passivation method with the assistance of Ca(OH)₂. In the reaction process, Ca 2+ protects the active functional groups from overconsumption during dehydration and carbonization, and the electron-withdrawing groups on the CD surface are converted to electron-donating groups by the hydroxyl ions. As a result, the fluorescence quantum yield of the CDs was found to increase with increasing Ca(OH)₂ content in the reaction process. A blue-shift optical spectrum of the CDs was also found with increasing Ca(OH)₂ content, which could be attributed to the increasing of the energy gaps for the CDs. The highly photoluminescent CDs obtained (quantum yield: 86%) were used to cultivate fluorescent carnations by a water culture method, while the results of fluorescence microscopy analysis indicated that the CDs had entered the plant tissue structure.

  7. High resolution optically stimulated luminescence dating of a sediment core from the southwestern Sea of Okhotsk

    DEFF Research Database (Denmark)

    Sugisaki, S.; Buylaert, J. P.; Murray, A. S.

    2012-01-01

    (D-e), with stimulation by both infrared and blue light. The suitability of the measurement procedure was confirmed using dose recovery tests. A high resolution record (similar to 2 OSL ages/m) identified clear sedimentation rate changes down the core. The OSL ages are significantly dependent......Optically stimulated luminescence (OSL) dating is now widely accepted as a chronometer for terrestrial sediment. More recently, it has been suggested that OSL may also be useful in the dating of deep-sea marine sediments. In this paper, we test the usefulness of high resolution quartz OSL dating...... in application to a 19 m marine sediment core (MR0604-PC04A) taken from the southwestern Sea of Okhotsk, immediately to the north of Hokkaido, Japan. Fine-grained quartz (4 to 11 mu m) was chosen as the dosimeter, and a single-aliquot regenerative-dose protocol was used for the determination of equivalent dose...

  8. Characterisation of blue-light stimulated luminescence components in different quartz samples: Implications for dose measurement

    DEFF Research Database (Denmark)

    Jain, M.; Murray, A.S.; Bøtter-Jensen, L.

    2003-01-01

    -aliquot dose-evaluation protocols seem to be relatively free of complications when applied to quartz dominated by the fast OSL component coming from 325degreesC TL region, but this may not be true for quartz in which other components are more significant. An adequate understanding of how different OSL...... results from measurement of (a) sensitisation, (b) thermal stability, (c) recuperation, and (d) infrared response as a function of stimulation temperature from 3 different samples of sedimentary quartz selected on the basis of relative OSL contribution from different blue light stimulated linearly...

  9. Synthesis and Luminescent Characteristics of Ce3+-Activated Borosilicate Blue-Emitting Phosphors for LEDs

    OpenAIRE

    Yu, Hong; Chen, Jinlei; Gan, Shucai

    2016-01-01

    The phosphors Sr3B2SiO8:Ce3+ have been successfully synthesized via solid-state reaction process. Emission/excitation spectra and photoluminescence decay behaviors were investigated in detail. Under the excitation of 340 nm, the emission spectrum presented an asymmetry emission band extended from 350 to 600 nm, which with the main peak at 425 nm can be fitted in two peaks (23940 cm−1 and 21934 cm−1). The chromaticity coordinates of Sr3-xB2SiO8:xCe3+ are fixed in the blue region; when the inte...

  10. Study on luminescence characteristics of blue OLED with phosphor-doped host-guest structure

    Science.gov (United States)

    Wang, Zhen; Liu, Fei; Zheng, Xin; Chen, Ai; Xie, Jia-feng; Zhang, Wen-xia

    2018-05-01

    In this study, we design and fabricate phosphor-doped host-guest structure organic light-emitting diodes (OLEDs), where the blue-ray iridium complex electrophosphorescent material FIrpic acts as object material. Properties of the device can be accommodated by changing the host materials, dopant concentration and thickness of the light-emitting layer. The study shows that the host material N,N'-dicarbazolyl-3,5-benzene (mCP) has a higher triplet excited state energy level, which can effectively prevent FIrpic triplet excited state energy backtracking to host material, thus the luminous efficiency is improved. When mCP is selected as the host material, the thickness of the light-emitting layer is 30 nm and the dopant concentration is 8 wt%, the excitons can be effectively confined in the light-emitting region. As a result, the maximum current efficiency and the maximum brightness of the blue device can reach 15.5 cd/A and 7 196.3 cd/m2, respectively.

  11. Synthesis and Luminescent Characteristics of Ce3+-Activated Borosilicate Blue-Emitting Phosphors for LEDs

    Directory of Open Access Journals (Sweden)

    Hong Yu

    2016-01-01

    Full Text Available The phosphors Sr3B2SiO8:Ce3+ have been successfully synthesized via solid-state reaction process. Emission/excitation spectra and photoluminescence decay behaviors were investigated in detail. Under the excitation of 340 nm, the emission spectrum presented an asymmetry emission band extended from 350 to 600 nm, which with the main peak at 425 nm can be fitted in two peaks (23940 cm−1 and 21934 cm−1. The chromaticity coordinates of Sr3-xB2SiO8:xCe3+ are fixed in the blue region; when the intensity of Ce3+ reached the maximum, the chromaticity coordinate is (0.154, 0.088 which is more close to the standard CIE of blue light (0.140, 0.080. The results showed the kind of phosphor may have potential applications in the fields of UV-excited white LEDs.

  12. SMART design to control over conformation and molecular packing in blue luminescent oligofluorenes

    Science.gov (United States)

    Yu, Meng-Na; Ou, Chang-Jin; Liu, Bin; Xie, Ling-Hai; Lin, Jin-Yi; Wang, Sha-Sha; Wei, Ying; Huang, Wei

    2018-01-01

    The uncertainty evolution of conformation and molecular packing from solution to film is key challenge for the repeatability of procedures in organic optoelectronics. Herein, we observed the noncovalent force at the bulky groups to decode the supramolecular steric hindrance (SSH) effect and to propose synergistically molecular attractor-repulsor theory (SMART). The fine difference between ideal and real bulks were described and the SSH effect have been proved by two comparable stat-of-the-art models. The SMART design guide us to discover blue oligo/polydiarylfluorenes with beta phase as well as nanosheets with the paradigm of Interdigital Lipid Bilayer-like (ILB) mode. SMART address one kind of AR molecules with potential controllable behaviors. The design of bulk-withdraw and bulk-rich will exhibit the unreplaceable role in morphology-directed design that is just like the role of donor-acceptor molecular design of organic polymer semiconductors.

  13. Excellent green but less impressive blue luminescence from CsPbBr3 perovskite nanocubes and nanoplatelets

    Science.gov (United States)

    Ravi, Vikash Kumar; Swarnkar, Abhishek; Chakraborty, Rayan; Nag, Angshuman

    2016-08-01

    Green photoluminescence (PL) from CsPbBr3 nanocubes (˜11 nm edge-length) exhibits a high quantum yield (>80%), narrow spectral width (˜85 meV), and high reproducibility, along with a high molar extinction coefficient (3.5 × 106 M-1 cm-1) for lowest energy excitonic absorption. In order to obtain these combinations of excellent properties for blue (PL peak maximum, λ max CsPbBr3 nanocubes and nanoplatelets with various dimensions were prepared. Systematic increases in both the optical gap and transition probability for radiative excitonic recombination (PL lifetime 3-7 ns), have been achieved with the decreasing size of nanocubes. A high quantum yield (>80%) was also maintained, but the spectral width increased and became asymmetric for blue emitting CsPbBr3 nanocubes. Furthermore, PL was unstable and irreproducible for samples with λ max ˜ 460 nm, exhibiting multiple features in the PL. These problems arise because smaller (CsPbBr3 nanocubes have a tendency to form nanoplatelets and nanorods, eventually yielding inhomogeneity in the shape and size of blue-emitting nanocrystals. Reaction conditions were then modified achieving nanoplatelets, with strong quantum confinement along the thickness of the platelets, yielding blue emission. But inhomogeneity in the thickness of the nanoplatelets again broadens the PL compared to green-emitting CsPbBr3 nanocubes. Therefore, unlike high quality green emitting CsPbBr3 nanocubes, blue emitting CsPbBr3 nanocrystals of any shape need to be improved further.

  14. Highly luminescent Eu{sup 3+}-doped benzenetricarboxylate based materials

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Ivan G.N. [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil); Mustafa, Danilo, E-mail: dmustafa@iq.usp.br [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil); Andreoli, Bruno [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil); Felinto, Maria C.F.C. [Centro de Química do Meio Ambiente, Instituto de Pesquisas Energéticas e Nucleares, Av. Prof. Lineu Prestes 2242, São Paulo 05508-000, SP (Brazil); Malta, Oscar L. [Departamento de Química Fundamental, Universidade Federal de Pernambuco, Av. Prof. Moraes Rego, 1235, Recife 50670-90, PE (Brazil); Brito, Hermi F., E-mail: hefbrito@iq.usp.br [Departamento de Química Fundamental, Instituto de Química da Universidade de São Paulo, Av. Prof. Lineu Prestes 748, São Paulo 05508-900, SP (Brazil)

    2016-02-15

    [RE(TMA)] anhydrous complexes (RE{sup 3+}: Y, Gd and Lu) present high red emission intensity with a quantum efficiency (~45%) for the [Y(TMA):Eu{sup 3+}] complexes, due to the absence of non-radioactive decay pathways mediated by water molecules. The complexes were prepared in mild conditions. All the compounds are crystalline and thermostable up to 460 °C. Phosphorescence data of the complexes with Y, Gd and Lu show that the T{sub 1} state of the TMA{sup 3−} anion has energy higher than the {sup 5}D{sub 0} emitting level of the Eu{sup 3+} ion, indicating that the ligand can act as an intramolecular energy sensitizer. The photoluminescence properties of the doped materials were studied based on the excitation and emission spectra and luminescence decay curves. The experimental intensity parameters (Ω{sub λ}), lifetimes (τ), radiative (A{sub rad}) and non-radiative (A{sub nrad}) decay rates were determined and discussed. - Highlights: • Highly luminescent Europium doped anhydrous complexes. • Efficient monochromatic red light conversion molecular devices (LCMDs). • High emission quantum efficiencies.

  15. Facile synthetic method for pristine graphene quantum dots and graphene oxide quantum dots: origin of blue and green luminescence.

    Science.gov (United States)

    Liu, Fei; Jang, Min-Ho; Ha, Hyun Dong; Kim, Je-Hyung; Cho, Yong-Hoon; Seo, Tae Seok

    2013-07-19

    Pristine graphene quantum dots and graphene oxide quantum dots are synthesized by chemical exfoliation from the graphite nanoparticles with high uniformity in terms of shape (circle), size (less than 4 nm), and thickness (monolayer). The origin of the blue and green photoluminescence of GQDs and GOQDs is attributed to intrinsic and extrinsic energy states, respectively. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Highly luminescent and photostable quantum dot-silica monolith and its application to light-emitting diodes.

    Science.gov (United States)

    Jun, Shinae; Lee, Junho; Jang, Eunjoo

    2013-02-26

    A highly luminescent and photostable quantum dot-silica monolith (QD-SM) substance was prepared by preliminary surface exchange of the QDs and base-catalyzed sol-gel condensation of silica. The SM was heavily doped with 6-mercaptohexanol exchanged QDs up to 12 vol % (26 wt %) without particle aggregation. Propylamine catalyst was important in maintaining the original luminescence of the QDs in the SM during sol-gel condensation. The silica layer was a good barrier against oxygen and moisture, so that the QD-SM maintained its initial luminescence after high-power UV radiation (∼1 W) for 200 h and through the 150 °C LED encapsulant curing process. Green and red light-emitting QD-SMs were applied as color-converting layers on blue LEDs, and the external quantum efficiency reached up to 89% for the green QD-SM and 63% for the red one. A white LED made with a mixture of green and red QDs in the SM, in which the color coordinate was adjusted at (0.23, 0.21) in CIE1931 color space for a backlight application, showed an efficacy of 47 lm/W, the highest value yet reported.

  17. Synthesis, Thermal and Luminescence Characteristics of Eu-activated SrZn2Si2O7 as a Nanocrystalline Blue-emitting Phosphor for LEDs Application

    International Nuclear Information System (INIS)

    Sameie, H.; Salimi, R.; Alvani, A.A.S.; Sarabi, A.A.; Farsi, M.A.M.; Roohnikan, M.; Mohammadloo, H.E.; Tahriri, M.

    2011-01-01

    In this research, blue-emitting nanocrystalline phosphor SrZn 2 Si 2 O 7 : Eu 2+ was successfully synthesized with two routes: solid state reaction (SS) and sol-gel method (SG). The effects of preparation processes on the crystallization, morphology and optical properties were investigated by appropriate techniques. From the photoluminescence results, obtained phosphors emit strong blue light due to 4f 6 5d 1 ( 2 D)→4f 7 ( 8 S 7/2 ) transition of Eu 2+ ions which act as luminescence centers. The experimental results reveal that the excitation and emission intensities for SS are better than SG due to higher calcination temperature, whereas the samples synthesized by wet chemical method have relatively regular morphology. (author)

  18. Visible luminescence from highly textured Tb{sup 3+} doped RF sputtered zinc oxide films

    Energy Technology Data Exchange (ETDEWEB)

    Sreedharan, R. Sreeja; Krishnan, R. Reshmi; Bose, R. Jolly; Kavitha, V.S.; Suresh, S. [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India); Vinodkumar, R. [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India); Department of Physics, University College, Thiruvananthapuram, Kerala (India); Sudheer, S.K. [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India); Pillai, V.P. Mahadevan, E-mail: vpmpillai9@gmail.com [Department of Optoelectronics, University of Kerala, Thiruvananthapuram 695581, Kerala (India)

    2017-04-15

    Highly transparent, luminescent, c-axis oriented Tb{sup 3+} doped ZnO films are prepared by RF magnetron sputtering technique. The structural, morphological, optical and luminescence properties of these films are investigated as a function of Tb{sup 3+} doping concentration by X-ray diffraction (XRD), micro-Raman spectroscopy, atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), spectroscopic ellipsometry, UV-Visible spectroscopy and photoluminescence spectroscopy. The as-deposited films are found to be highly crystalline with wurtzite hexagonal phase of ZnO. The characteristic features of hexagonal wurtzite structure of ZnO, particularly the appearance of non-polar E{sub 2} modes are easily identified from the Raman spectra of the films. The surface morphology of the films revealed by FESEM and AFM images present a dense distribution of grains. The elemental analysis carried out using energy dispersive X-ray (EDX) spectra confirms the incorporation of Tb{sup 3+} ions in the ZnO lattice. The films are highly transparent in the visible region. Using ellipsometric analysis, the variation of refractive index, dielectric constant and thickness of the films are studied as a function of Tb{sup 3+} doping concentration. The photoluminescence spectra of the Tb{sup 3+} doped ZnO films recorded using an excitation radiation of wavelength 325 nm from a He-Cd laser exhibit visible luminescence ~430, 490, 516 and 542 nm. The origin of visible emissions ~490 and 542 nm in the doped films can be attributed to 5D{sub 4}→7F{sub 6} and 5D{sub 4}→7F{sub 5} transition of Tb{sup 3+} ion respectively. The intensity of the emission at 542 nm is found to be decreasing at higher doping concentration due to concentration quenching effect. The blue emission in the films can be attributed to the electron transition from shallow donor level formed by interstitial Zn atoms to the top of the valence band. The origin of the visible emission ~516 nm is attributed

  19. Studies on highly luminescent AgInS{sub 2} and Ag–Zn–In–S quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Xiang, Weidong, E-mail: xiangweidong001@126.com [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China); College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Xie, Cuiping; Wang, Jing; Zhong, Jiasong; Liang, Xiaojuan; Yang, Hailong; Luo, Le [College of Materials Science and Engineering, Tongji University, Shanghai 201804 (China); Chen, Zhaoping [College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035 (China)

    2014-03-05

    Highlights: • The quantum yield of the obtained ternary AgInS{sub 2} QDs was up to 62% with the emission peak of 642 nm under the excitation of 460 nm. • Colorful luminescent Ag–Zn–In–S QDs were obtained by adding Zn salts directly as well as Ag and In precursors. • The obtained highly luminescent quantum dots showed promising applications in the white light emitting diodes (W-LED). • The electroluminescence (EL) of AgInS{sub 2} QDs was observed in QD-LED device. -- Abstract: Silver indium sulfide (AIS) quantum dots (QDs) with different Ag/In molar ratios were synthesized via a hot-injection method. Intense photoluminescence (PL) originating from the donor–acceptor pair recombination were observed for all the samples and the emission peak blue-shifted from 739 to 632 nm, being similar to the behavior of the absorption onset as the Ag/In ratios decreased. The highest PL quantum yield (QY) of the obtained ternary AIS QDs was ca. 62% with an optimum ratio of Ag/In = 1/4. Compared with AIS QDs, when Zn ions were introduced, the absorption spectra of the obtained quaternary Ag–Zn–In–S QDs were blue-shifted, and their emission peaks moved to higher energies accordingly, showing a tunable emission from red to green by altering the band gap energy. In order to further study the electroluminescence (EL) as well as looking forward to the applications in the optoelectronic devices of the obtained highly luminescent nanoparticles, the colloidal AIS QDs were deposited as thin films to the sandwich-like structured QD-LED. The experimental results showed that the obtained EL device exhibited EL emission originated from QDs thin films by adjusting the turn on voltage, which is for the first time to realize EL of AIS QDs in such QD-LED.

  20. Origin and Luminescence of Anomalous Red-Emitting Center in Rhombohedral Ba9Lu2Si6O24:Eu(2+) Blue Phosphor.

    Science.gov (United States)

    Liu, Yongfu; Zhang, Changhua; Cheng, Zhixuan; Zhou, Zhi; Jiang, Jun; Jiang, Haochuan

    2016-09-06

    We obtain a blue phosphor, Ba9Lu2Si6O24:Eu(2+) (BLS:Eu(2+)), which shows a strong emission peak at 460 nm and a weak tail from 460 to 750 nm. A 610 nm red emission is observed for the first time in this kind of rhombohedral structure material, which is much different from the same crystal structure of Ba9Sc2Si6O24:Eu(2+) and Ba9Y2Si6O24:Eu(2+). The luminescence properties and decays from 10 to 550 K are discussed. The new red emission arises from a trapped exciton state of Eu(2+) at the Ba site with a larger coordination number (12-fold). It exhibits abnormal luminescence properties with a broad bandwidth and a large Stokes shift. Under the 400 nm excitation, the external quantum efficiency of BLS:Eu(2+) is 45.4%, which is higher than the 35.7% for the commercial blue phosphor BAM:Eu(2+). If the thermal stability of BLS:Eu(2+) can be improved, it will show promising applications in efficient near-UV-based white LEDs.

  1. Highly visible-light luminescence properties of the carboxyl-functionalized short and ultrashort MWNTs

    International Nuclear Information System (INIS)

    Luo Yongsong; Xia Xiaohong; Liang Ying; Zhang Yonggang; Ren Qinfeng; Li Jialin; Jia Zhijie; Tang Yiwen

    2007-01-01

    Luminescence of the short multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups has been studied. The results show that the carboxyl-functionalized short MWNTs could emit luminescence and the emission peak appears at 500 nm with a corresponding optimal excitation wavelength centering at 310 nm. When the short MWNTs are filtered through 0.15 μm polytetrafluoroethylene (PTFE) membrane, the ultrashort MWNTs are obtained from the filtrate. An interesting feature for the ultrashort MWNTs is that the emission intensity is strengthened and the peak is slightly blue shifted to 460 nm. This result indicates that the luminescence properties of MWNTs are strongly affected by the tube length. After chemical oxidization cutting, defects and carboxylic acid groups at the tube end and/or sidewall can be produced; the more shorten of MWNTs, the better dispersion and carboxylic passivation of the nanotubes, and the more intense luminescence emissions. The broad emissions are logically attributed to the trapping of excitation energy by defect sites in the carboxyl-functionalized nanotube structure. - Graphical abstract: Luminescence of the short and ultrashort multiwalled carbon nanotubes (MWNTs) conjugated with carboxylic acid groups, which is logically attributed to the trapping of excitation energy by defect sites, has been studied

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

    International Nuclear Information System (INIS)

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

    2008-01-01

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

  3. Enhancement of blue upconversion luminescence in hexagonal NaYF{sub 4}:Yb,Tm by using K and Sc ions

    Energy Technology Data Exchange (ETDEWEB)

    Kale, Vishal, E-mail: vishal.kale@utu.fi; Soukka, Tero [University of Turku, Department of Biochemistry and Food Chemistry/Biotechnology (Finland); Hoelsae, Jorma; Lastusaari, Mika [University of Turku, Department of Chemistry (Finland)

    2013-08-15

    Hexagonal ({beta})-NaYF{sub 4} is recognized as one of the most efficient hosts for NIR to blue and green upconversion (UC). A new method to tune the blue UC emission in {beta}-NaYF{sub 4}:Yb,Tm nanocrystals through the possible substitution of the host material with different concentrations of K{sup +} and Sc{sup 3+} ions was investigated in detail. In this work, Na{sub 1-x}K{sub x}YF{sub 4}:Yb,Tm and NaY{sub 1-x}Sc{sub x}F{sub 4}:Yb,Tm nanocrystals were synthesized with varying Na:K and Y:Sc ratios. X-ray diffraction, transmission electron microscopy, and UC luminescence spectroscopy showed that size, morphology, and UC luminescence intensity were affected by the addition of K{sup +} and Sc{sup 3+} ions. Substituted ions disturbed the local symmetry and also resulted in changes in the crystal field. The distance between Yb{sup 3+} and Tm{sup 3+} was affected by different concentration of K{sup +} and Sc{sup 3+} ions, and those differences in the distance are responsible for tuning UC luminescence. This study revealed that when the concentration of K{sup +} and Sc{sup 3+} ions were nominally increased from 20 to 100 mol% during synthesis, hexagonal NaYF{sub 4} changed to structurally different KYF{sub 4} and Na{sub 3}ScF{sub 6} so that the solid solubility became difficult. We also demonstrate that the added K{sup +} does not enter into the NaYF{sub 4} lattice, but it still plays an important role by controlling the Na/R ratio. K{sup +} and Sc{sup 3+} ion concentration of 20 mol% during the synthesis was found to result in materials with size 30-35 nm, and shows ca. four times brighter UC emission than the previously reported lanthanide based nanocrystals. The enhancement in UC luminescence intensity makes upconversion nanophosphors versatile imaging tools for diagnosis.Graphical Abstract.

  4. Polarization memory of white luminescence of Ag nanoclusters dispersed in glass host.

    Science.gov (United States)

    Kuznetsov, A S; Tikhomirov, V K; Moshchalkov, V V

    2012-09-10

    A mechanism for white luminescence of Ag nanoclusters dispersed in oxyfluoride glass host has been revealed by studying a temperature dependence of its polarization memory. The spectral dependence of the polarization memory indicates the presence of a variety of Ag nanoclusters, particularly emitting in the blue, green and red. Temperature activated intercluster energy transfer has been found responsible for white luminescence. The means for increasing luminescence quantum yield have been suggested. This efficient white luminescence may be used in highly demanded devices, such as luminescent lamps, displays, color phosphors for LEDs, photovoltaic devices based on down shifting of solar spectrum.

  5. High-resolution light microscopy using luminescent nanoparticles.

    Science.gov (United States)

    Ohulchanskyy, Tymish Y; Roy, Indrajit; Yong, Ken-Tye; Pudavar, Haridas E; Prasad, Paras N

    2010-01-01

    This review presents recent progress in the development of the luminescent nanoparticles for confocal and multiphoton microscopy. Four classes of nanomaterials are discussed: (1) silica-based nanoparticles doped with fluorescent molecules, (2) gold nanoparticles, (3) semiconductor nanocrystals (quantum dots/rods), and (4) nanophosphors. Special considerations are given to recently developed imaging nanoprobes, such as (1) organically modified silica (ORMOSIL) nanoparticles doped with two-photon absorbing fluorophores, which exhibit aggregation-enhanced fluorescence (AEF), and (2) nanophosphors (ceramic nanoparticles containing luminescent lanthanoid ions). Advantages and disadvantages of every class of nanomaterials and their specific applications are briefly discussed.

  6. Luminescence decay in condensed argon under high energy excitation

    International Nuclear Information System (INIS)

    Carvalho, M.J.; Klein, G.

    1978-01-01

    α and β particles were used to study the luminescence of condensed argon. The scintillation decay has always two components independently of the phase and the kind of the exciting particles. Decay time constants are given for solid, liquid and also gaseous argon. Changes in the relative intensity values of the two components are discussed in terms of track effects

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-07-01

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

  8. Microscopic origin of the fast blue-green luminescence of chemically synthesized non-oxidized silicon quantum dots

    NARCIS (Netherlands)

    Dohnalova, K.; Fucikova, A.; Umesh, C.P.; Humpolickova, J.; Paulusse, Jos Marie Johannes; Valenta, J.; Zuilhof, H.

    2012-01-01

    The microscopic origin of the bright nanosecond blue-green photoluminescence (PL), frequently reported for synthesized organically terminated Si quantum dots (Si-QDs), has not been fully resolved, hampering potential applications of this interesting material. Here a comprehensive study of the PL

  9. Microscopic Origin of the Fast Blue-Green Luminescence from Chemically Synthesized Non-Oxidized Silicon Quantum Dots

    NARCIS (Netherlands)

    Dohnalová, K.; Gregorkiewicz, T.; Fucíková, A.; Valenta, J.; Umesh, C.; Paulusse, J.M.J.; Zuilhof, H.; Humpolícková, J.; Hof, van M.

    2012-01-01

    The microscopic origin of the bright nanosecond blue-green photoluminescence (PL), frequently reported for synthesized organically terminated Si quantum dots (Si-QDs), has not been fully resolved, hampering potential applications of this interesting material. Here a comprehensive study of the PL

  10. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu3+ phosphors and ceramics

    OpenAIRE

    Janulevičius, Matas; Marmokas, Paulius; Misevičius, Martynas; Grigorjevaitė, Julija; Mikoliūnaitė, Lina; Šakirzanovas, Simas; Katelnikovas, Artūras

    2016-01-01

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu3+ phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu3+ showed quantum yields up to 85%, what is suitable for commercial application. Temperature depend...

  11. High-luminosity blue and blue-green gallium nitride light-emitting diodes.

    Science.gov (United States)

    Morkoç, H; Mohammad, S N

    1995-01-06

    Compact and efficient sources of blue light for full color display applications and lighting eluded and tantalized researchers for many years. Semiconductor light sources are attractive owing to their reliability and amenability to mass manufacture. However, large band gaps are required to achieve blue color. A class of compound semiconductors formed by metal nitrides, GaN and its allied compounds AIGaN and InGaN, exhibits properties well suited for not only blue and blue-green emitters, but also for ultraviolet emitters and detectors. What thwarted engineers and scientists from fabricating useful devices from these materials in the past was the poor quality of material and lack of p-type doping. Both of these obstacles have recently been overcome to the point where highluminosity blue and blue-green light-emitting diodes are now available in the marketplace.

  12. Highly Water-Stable Lanthanide-Oxalate MOFs with Remarkable Proton Conductivity and Tunable Luminescence.

    Science.gov (United States)

    Zhang, Kun; Xie, Xiaoji; Li, Hongyu; Gao, Jiaxin; Nie, Li; Pan, Yue; Xie, Juan; Tian, Dan; Liu, Wenlong; Fan, Quli; Su, Haiquan; Huang, Ling; Huang, Wei

    2017-09-01

    Although proton conductors derived from metal-organic frameworks (MOFs) are highly anticipated for various applications including solid-state electrolytes, H 2 sensors, and ammonia synthesis, they are facing serious challenges such as poor water stability, fastidious working conditions, and low proton conductivity. Herein, we report two lanthanide-oxalate MOFs that are highly water stable, with so far the highest room-temperature proton conductivity (3.42 × 10 -3 S cm -1 ) under 100% relative humidity (RH) among lanthanide-based MOFs and, most importantly, luminescent. Moreover, the simultaneous response of both the proton conductivity and luminescence intensity to RH allows the linkage of proton conductivity with luminescence intensity. This way, the electric signal of proton conductivity variation versus RH will be readily translated to optical signal of luminescence intensity, which can be directly visualized by the naked eye. If proper lanthanide ions or even transition-metal ions are used, the working wavelengths of luminescence emissions can be further extended from visible to near infrared light for even wider-range applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Fabrication and spectroscopic studies on highly luminescent CdSe/CdS nanorod polymer composites

    NARCIS (Netherlands)

    Bomm, J.; Büchtemann, A.; Fiore, Angela; Manna, L.; Nelson, J.H.; Hill, D.; van Sark, W.G.J.H.M.

    2010-01-01

    Highly luminescent nanocomposites were prepared by incorporating CdSe/CdS core/shell nanorods into different polymer matrices. The resulting nanocomposites show high transparency of up to 93%. A photoluminescence quantum efficiency of 70% was obtained, with an optimum combination of nanorod (0.05 wt

  14. Characterization of Thymol blue Radiochromic dosimeters for high dose applications

    Directory of Open Access Journals (Sweden)

    Feras M. Aldweri

    2018-03-01

    Full Text Available Thymol blue (TB solutions and Thymol blue Polyvinyl Alcohol (TB-PVA films have been introduced as Radiochromic dosimeter for high dose applications. The dosimeters were irradiated with gamma ray (60Co source from 5 to 30 kGy for film, and from 0.150 kGy to 4 kGy for solution. The optical density of unirradiated and irradiated TB solution as well as TB-PVA film dosimeters were studied in terms of absorbance at 434 nm using UV/VIS spectrophotometer. The effects of scan temperature, light pre-gamma irradiation, dose rate, relative humidity and stability of the absorbance of solutions and films after irradiation were investigated. We found the dose sensitivity of TB solution and TB-PVA film dosimeters increases significantly with increases of the absorbed dose as well as with the increases of TB dye concentrations. The useful dose range of developed TB solutions and TB-PVA films dosimeters is in the range 0.125–1 kGy and of 5–20 kGy, respectively. Keywords: Dose sensitivity, Radio-chromic dosimeter, Thymol blue, Absorbance, Concentrations

  15. Luminescent properties of Eu2+-doped BaGdF5 glass ceramics a potential blue phosphor for ultra-violet light-emitting diode

    International Nuclear Information System (INIS)

    Zhang, Weihuan; Zhang, Yuepin; Ouyang, Shaoye; Zhang, Zhixiong; Wang, Qian; Xia, Haiping

    2015-01-01

    Eu 2+ doped transparent oxyfluoride glass ceramics containing BaGdF 5 nanocrystals were successfully fabricated by melt-quenching technique under a reductive atmosphere. The structure of the glass and glass ceramics were investigated by differential scanning calorimetry, X-ray diffraction (XRD), and transmission electron microscopy (TEM). The luminescent properties were investigated by transmission, excitation, and emission spectra. The decay time of the Gd 3+ ions at 312 nm excited with 275 nm were also investigated. The results of XRD and TEM indicated the existence of BaGdF5 nanocrystals in the transparent glass ceramics. The excitation spectra of Eu 2+ doped glass ceramics showed an excellent overlap with the main emission region of an ultraviolet light-emitting diode (UV-LED). Compared with the as-made glass, the emission of glass ceramics is much stronger by a factor of increasing energy transfer efficiency from Gd 3+ to Eu 2+ ions, the energy transfer efficiency from Gd 3+ to Eu 2+ ions was discussed. In addition, the chromaticity coordinates of glass and glass ceramics specimens were also discussed, which indicated that the Eu 2+ doped BaGdF 5 glass ceramics may be used as a potential blue-emitting phosphor for UV-LED

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

    International Nuclear Information System (INIS)

    Klick, D.I.

    1977-01-01

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

  17. Highly sensitive luminescence method of scandium determination in the products of metallurgical reprocessing

    International Nuclear Information System (INIS)

    Matveets, M.A.; Akhmetova, S.D.

    1988-01-01

    Highly sensitive reaction of scandium with 1,10-phenanthroline and eosin is used for the development of luminescence method of its determination in metallurgical products. The effect of interfering elements is eliminated by scandium extraction with monocarboxylic acids. The method permits to determine scandium content from 5 x 10 -5 % (Sr 0.15 - 0.25)

  18. High power blue LED development using different growth modes

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Dong S.; Florescu, Doru I.; Ramer, Jeff C.; Merai, Vinod; Parekh, Aniruddh; Begarney, Michael J.; Armour, Eric A. [Veeco TurboDisc Operations, 394 Elizabeth Avenue, Somerset, NJ 08873 (United States); Lu Dong [Veeco TurboDisc Operations, 394 Elizabeth Avenue, Somerset, NJ 08873 (United States); School of Engineering, Rutgers University, Piscataway, NJ 08854 (United States)

    2004-09-01

    Blue high brightness light emitting diodes (HB-LEDs) have been developed using different growth modes in the active layers. Piezoelectric field engineering improves the optical output power in multiple quantum well (MQW) LEDs by inserting an optimized transitional superlattice (TSL) before the active MQW layers. Within single quantum well (SQW) LEDs, quasi-Quantum Dot (QD) growth for Indium localization has been realized. The SQW LED output power exceeds the strain engineered MQW LEDs. The experimental data indicates that Indium localization enhances overall quantum efficiency and results in increased output power for HB-LEDs. (copyright 2004 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  19. Microscopic origin of the fast blue-green luminescence of chemically synthesized non-oxidized silicon quantum dots.

    Science.gov (United States)

    Dohnalová, Kateřina; Fučíková, Anna; Umesh, Chinnaswamy P; Humpolíčková, Jana; Paulusse, Jos M J; Valenta, Jan; Zuilhof, Han; Hof, Martin; Gregorkiewicz, Tom

    2012-10-22

    The microscopic origin of the bright nanosecond blue-green photoluminescence (PL), frequently reported for synthesized organically terminated Si quantum dots (Si-QDs), has not been fully resolved, hampering potential applications of this interesting material. Here a comprehensive study of the PL from alkyl-terminated Si-QDs of 2-3 nm size, prepared by wet chemical synthesis is reported. Results obtained on the ensemble and those from the single nano-object level are compared, and they provide conclusive evidence that efficient and tunable emission arises due to radiative recombination of electron-hole pairs confined in the Si-QDs. This understanding paves the way towards applications of chemical synthesis for the development of Si-QDs with tunable sizes and bandgaps. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Preparation of carbon quantum dots based high photostability luminescent membranes.

    Science.gov (United States)

    Zhao, Jinxing; Liu, Cui; Li, Yunchuan; Liang, Jiyuan; Liu, Jiyan; Qian, Tonghui; Ding, Jianjun; Cao, Yuan-Cheng

    2017-06-01

    Urethane acrylate (UA) was used to prepare carbon quantum dots (C-dots) luminescent membranes and the resultants were examined with FT-IR, mechanical strength, scanning electron microscope (SEM) and quantum yields (QYs). FT-IR results showed the polyurethane acrylate (PUA) prepolymer -C = C-vibration at 1101 cm -1 disappeared but there was strong vibration at1687cm -1 which was contributed from the-C = O groups in cross-linking PUA. Mechanical strength results showed that the different quantity of C-dots loadings and UV-curing time affect the strength. SEM observations on the cross-sections of the membranes are uniform and have no structural defects, which prove that the C-dots are compatible with the water-soluble PUA resin. The C-dot loading was increased from 0 to 1 g, the maximum tensile stress was nearly 2.67 MPa, but the tensile strain was decreased from 23.4% to 15.1% and 7.2% respectively. QYs results showed that the C-dots in the membrane were stable after 120 h continuous irradiation. Therefore, the C-dots photoluminescent film is the promising material for the flexible devices in the future applications. Copyright © 2016 John Wiley & Sons, Ltd.

  1. High-temperature peaks of thermostimulated luminescence in the ammonium halogens

    International Nuclear Information System (INIS)

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

    2003-01-01

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

  2. Creating high yield water soluble luminescent graphene quantum dots via exfoliating and disintegrating carbon nanotubes and graphite flakes.

    Science.gov (United States)

    Lin, Liangxu; Zhang, Shaowei

    2012-10-21

    We have developed an effective method to exfoliate and disintegrate multi-walled carbon nanotubes and graphite flakes. With this technique, high yield production of luminescent graphene quantum dots with high quantum yield and low oxidization can be achieved.

  3. Homogeneous Synthesis and Electroluminescence Device of Highly Luminescent CsPbBr3 Perovskite Nanocrystals.

    Science.gov (United States)

    Wei, Song; Yang, Yanchun; Kang, Xiaojiao; Wang, Lan; Huang, Lijian; Pan, Daocheng

    2017-03-06

    Highly luminescent CsPbBr 3 perovskite nanocrystals (PNCs) are homogeneously synthesized by mixing toluene solutions of PbBr 2 and cesium oleate at room temperature in open air. We found that PbBr 2 can be easily dissolved in nonpolar toluene in the presence of tetraoctylammonium bromide, which allows us to homogeneously prepare CsPbBr 3 perovskite quantum dots and prevents the use of harmful polar organic solvents, such as N,N-dimethylformamide, dimethyl sulfoxide, and N-methyl-2-pyrrolidone. Additionally, this method can be extended to synthesize highly luminescent CH 3 NH 3 PbBr 3 perovskite quantum dots. An electroluminescence device with a maximal luminance of 110 cd/m 2 has been fabricated by using high-quality CsPbBr 3 PNCs as the emitting layer.

  4. Design, synthesis and characterization of a highly luminescent Eu-complex monomer featuring thenoyltrifluoroacetone and 5-acryloxyethoxymethyl-8-hydroxyquinoline

    Energy Technology Data Exchange (ETDEWEB)

    Xu Cunjin [State Key Laboratory of Chemical Engineering, Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China); College of Material, Chemistry and Chemical Engineering, Hangzhou Normal University, Hangzhou 310036 (China); Li Bogeng, E-mail: bgli@zju.edu.cn [State Key Laboratory of Chemical Engineering, Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China); Wan Jintao; Bu Zhiyang [State Key Laboratory of Chemical Engineering, Department of Chemical and Biochemical Engineering, Zhejiang University, Hangzhou 310027 (China)

    2011-08-15

    A multi-functional ligand, 5-acryloxyethoxymethyl-8-hydroxyquinoline (Hamq), was synthesized, which contained a polymerizable C=C double bond for the copolymerization with other vinyl monomers and acted as photon antenna able to transfer energy to Eu{sup 3+} ions effectively. The triplet state energy of Hamq was determined to be 22,370 cm{sup -1} via the phosphorescence spectra of Hamq and its gadolinium complex. The title complex monomer Eu(tta){sub 2}(amq) was prepared by coordination reaction of Hamq with europium isopropoxide and 2-thenoyltrifluoroacetone (Htta) in dry organic solvents under argon atmosphere and characterized by elemental analysis and IR spectrum. The photophysical properties of the complex were studied in detail with UV-vis, luminescence spectra, luminescence lifetime and quantum yield. The complex exhibited nearly monochromatic red emission at 612 nm, a remarkable luminescence quantum yield at room temperature (30.6%) upon ligand excitation and a long {sup 5}D{sub 0} lifetime (389 {mu}s), which indicated that the ligand Hamq could sensitize the luminescence of Eu(III) ion efficiently in Eu(tta){sub 2}(amq), resulting in a strong luminescence of its copolymer poly[MMA-co-Eu(TTA){sub 2}(amq)] under UV excitation. The excellent luminescence properties of the complex made it not only a promising light-conversion molecular device but also an excellent luminescent monomer. - Highlights: >iWe designed and synthesized a highly luminescent Eu-complex monomer. > Quantum yield and lifetime of the complex are 30.6% and 389 {mu}s, respectively. > Excellent luminescence of the complex made it an excellent luminescent monomer.

  5. Conformal and highly luminescent monolayers of Alq3 prepared by gas-phase molecular layer deposition.

    Science.gov (United States)

    Räupke, André; Albrecht, Fabian; Maibach, Julia; Behrendt, Andreas; Polywka, Andreas; Heiderhoff, Ralf; Helzel, Jonatan; Rabe, Torsten; Johannes, Hans-Hermann; Kowalsky, Wolfgang; Mankel, Eric; Mayer, Thomas; Görrn, Patrick; Riedl, Thomas

    2014-01-22

    The gas-phase molecular layer deposition (MLD) of conformal and highly luminescent monolayers of tris(8-hydroxyquinolinato)aluminum (Alq3) is reported. The controlled formation of Alq3 monolayers is achieved for the first time by functionalization of the substrate with amino groups, which serve as initial docking sites for trimethyl aluminum (TMA) molecules binding datively to the amine. Thereby, upon exposure to 8-hydroxyquinoline (8-HQ), the self-limiting formation of highly luminescent Alq3 monolayers is afforded. The growth process and monolayer formation were studied and verified by in situ quartz crystal monitoring, optical emission and absorption spectroscopy, and X-ray photoelectron spectroscopy. The nature of the MLD process provides an avenue to coat arbitrarily shaped 3D surfaces and porous structures with high surface areas, as demonstrated in this work for silica aerogels. The concept presented here paves the way to highly sensitive luminescent sensors and dye-sensitized metal oxides for future applications (e.g., in photocatalysis and solar cells).

  6. Appearance of high submerged cavitating jet: The cavitation phenomenon and sono luminescence

    Directory of Open Access Journals (Sweden)

    Hutli Ezddin

    2013-01-01

    Full Text Available In order to study jet structure and behaviour of cloud cavitation within time and space, visualization of highly submerged cavitating water jet has been done using Stanford Optics 4 Quick 05 equipment, through endoscopes and other lenses with Drello3244 and Strobex Flash Chadwick as flashlight stroboscope. This included obligatory synchronization with several types of techniques and lenses. Images of the flow regime have been taken, allowing calculation of the non-dimensional cavitation cloud length under working conditions. Consequently a certain correlation has been proposed. The influencing parameters, such as; injection pressure, downstream pressure and cavitation number were experimentally proved to be very significant. The recordings of sono-luminescence phenomenon proved the collapsing of bubbles everywhere along the jet trajectory. In addition, the effect of temperature on sono-luminescence recordings was also a point of investigation. [Projekat Ministarstva nauke Republike Srbije, br. TR35046

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

    International Nuclear Information System (INIS)

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

    2013-01-01

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

  8. High-energy X-ray detection using organic luminescent materials: a novel application for radiation therapy

    International Nuclear Information System (INIS)

    Schimitberger, Thiago; Ferreira, Giovana Ribeiro; Silva, Mariana de Melo; Saraiva, M.F.; Bianchi, Rodrigo Fernando

    2010-01-01

    In this work, it is presented the characterization and fabrication of a novel ionizing radiation sensor for high energy X-ray (6 MeV). It is used organic luminescent materials usually applied in light-emitting and nanostructure device, but still few explored in radiation dosimetry. Organic solutions of tris(8-hydroxyquinolinato) aluminum - Alq_3 and poly[2-methoxy-5-(2'-ethylhexyloxy)-p-phenylene vinylene] - MEH-PPV were prepared to better study the impact of spectral overlap between the Alq_3 emission and MEH-PPV absorption. It is observed a blue-shift on the photoluminescence of the MEH-PPV/Alq_3 solution system from red-orange (λ_m_a_x = 598 nm) to green (λ_m_a_x = 545 nm) when the radiation dose changes from 0 to 100 Gy. This effect is attributed to the photooxidation process of MEH-PPV and was employed to design dose accumulation sensors in order to represent easily the radiation dose for cancer treatment. (author)

  9. A luminescent Lanthanide-free MOF nanohybrid for highly sensitive ratiometric temperature sensing in physiological range.

    Science.gov (United States)

    Zhou, You; Zhang, Denan; Zeng, Jin; Gan, Ning; Cuan, Jing

    2018-05-01

    Luminescent MOF materials with tunable emissions and energy/charge transfer processes have been extensively explored as ratiometric temperature sensors. However, most of the ratiometric MOF thermometers reported thus far are based on the MOFs containing photoactive lanthanides, which are potentially facing cost issue and serious supply shortage. Here, we present a ratiometric luminescent thermometer based on a dual-emitting lanthanide-free MOF hybrid, which is developed by encapsulation of a fluorescent dye into a robust nanocrystalline zirconium-based MOF through a one-pot synthesis approach. The structure and morphology of the hybrid product was characterized by Powder X-ray diffraction (PXRD), N 2 adsorption-desorption measurement and Scanning electron microscopy (SEM). The pore confinement effect well isolates the guest dye molecules and therefore suppresses the nonradiative energy transfer process between dye molecules. The incorporated dye emission is mainly sensitized by the organic linkers within MOF through fluorescence resonance energy transfer. The ratiometric luminescence of the MOF hybrid shows a significant response to temperature due to the thermal-related back energy transfer process from dye molecules and organic linkers, thus can be exploited for self-calibrated temperature sensing. The maximum thermometric sensitivity is 1.19% °C -1 in the physiological temperature range, which is among the highest for the ratiomtric MOF thermometers that operating in 25-45°C. The temperature resolution is better than 0.1°C over the entire operative range (20-60°C). By integrating the advantages of excellent stability, nanoscale nature, and high sensitivity and precision in the physiological temperature range, this dye@MOF hybrid might have potential application in biomedical diagnosis. What' more, this work has expanded the possibility of non-lanthanide luminescent MOF materials for the development of ratiometric temperature sensors. Copyright © 2018

  10. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu(3+) phosphors and ceramics.

    Science.gov (United States)

    Janulevicius, Matas; Marmokas, Paulius; Misevicius, Martynas; Grigorjevaite, Julija; Mikoliunaite, Lina; Sakirzanovas, Simas; Katelnikovas, Arturas

    2016-05-16

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu(3+) phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu(3+) showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu(3+) doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu(3+) phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour.

  11. Luminescence and luminescence quenching of highly efficient Y2Mo4O15:Eu3+ phosphors and ceramics

    Science.gov (United States)

    Janulevicius, Matas; Marmokas, Paulius; Misevicius, Martynas; Grigorjevaite, Julija; Mikoliunaite, Lina; Sakirzanovas, Simas; Katelnikovas, Arturas

    2016-01-01

    A good LED phosphor must possess strong enough absorption, high quantum yields, colour purity, and quenching temperatures. Our synthesized Y2Mo4O15:Eu3+ phosphors possess all of these properties. Excitation of these materials with near-UV or blue radiation yields bright red emission and the colour coordinates are relatively stable upon temperature increase. Furthermore, samples doped with 50% Eu3+ showed quantum yields up to 85%, what is suitable for commercial application. Temperature dependent emission spectra revealed that heavily Eu3+ doped phosphors possess stable emission up to 400 K and lose half of the efficiency only at 515 K. In addition, ceramic disks of Y2Mo4O15:75%Eu3+ phosphor with thickness of 0.71 and 0.98 mm were prepared and it turned out that they efficiently convert radiation of 375 and 400 nm LEDs to the red light, whereas combination with 455 nm LED yields purple colour. PMID:27180941

  12. Synthesis and Luminescence Properties of Blue Na(Sr0.97-xCa(x))PO4:0.03Eu2+ Phosphors for White Light Emitting Diode Applications.

    Science.gov (United States)

    Hakeem, D A; Park, K

    2015-07-01

    The crystal structure and luminescence properties of Na(Sr0.97-xCax)PO4:0.03Eu2+ (0 phosphors were studied, depending on the Ca2+ concentration. All the Na(Sr0.97-xCax)PO4:0.03Eu2+ phosphors had a hexagonal crystal structure. The excitation spectra of the prepared phosphors showed a broad band ranging from 250 to 420 nm, which arises due to the 4f-5d transitions of Eu2+ ions. Upon the excitation of 334 nm wavelength, the emission spectra showed a broad blue band ranging from 400 to 700 nm peaking at 450 nm. Among the prepared phosphors, the Na(Sr0.72Ca0.25)PO4:0.03Eu2+ showed the strongest emission intensity and could be applied as a blue emitting phosphor for UV-based w-LEDs.

  13. Characterization of three high efficiency and blue sensitive silicon photomultipliers

    Energy Technology Data Exchange (ETDEWEB)

    Otte, Adam Nepomuk, E-mail: otte@gatech.edu; Garcia, Distefano; Nguyen, Thanh; Purushotham, Dhruv

    2017-02-21

    We report about the optical and electrical characterization of three high efficiency and blue sensitive Silicon photomultipliers from FBK, Hamamatsu, and SensL. Key features of the tested devices when operated at 90% breakdown probability are peak photon detection efficiencies between 40% and 55%, temperature dependencies of gain and PDE that are less than 1%/°C, dark rates of ∼50 kHz/mm{sup 2} at room temperature, afterpulsing of about 2%, and direct optical crosstalk between 6% and 20%. The characteristics of all three devices impressively demonstrate how the Silicon-photomultiplier technology has improved over the past ten years. It is further demonstrated how the voltage and temperature characteristics of a number of quantities can be parameterized on the basis of physical models. The models provide a deeper understanding of the device characteristics over a wide bias and temperature range. They also serve as examples how producers could provide the characteristics of their SiPMs to users. A standardized parameterization of SiPMs would enable users to find the optimal SiPM for their application and the operating point of SiPMs without having to perform measurements thus significantly reducing design and development cycles.

  14. Highly Luminescent Lanthanide Complexes of 1 Hydroxy-2-pyridinones

    Energy Technology Data Exchange (ETDEWEB)

    University of California, Berkeley; Lawrence National Laboratory; Raymond, Kenneth; Moore, Evan G.; Xu, Jide; Jocher, Christoph J.; Castro-Rodriguez, Ingrid; Raymond, Kenneth N.

    2007-11-01

    The synthesis, X-ray structure, stability, and photophysical properties of several trivalent lanthanide complexes formed from two differing bis-bidentate ligands incorporating either alkyl or alkyl ether linkages and featuring the 1-hydroxy-2-pyridinone (1,2-HOPO) chelate group in complex with Eu(III), Sm(III) and Gd(III) are reported. The Eu(III) complexes are among some of the best examples, pairing highly efficient emission ({Phi}{sub tot}{sup Eu} {approx} 21.5%) with high stability (pEu {approx} 18.6) in aqueous solution, and are excellent candidates for use in biological assays. A comparison of the observed behavior of the complexes with differing backbone linkages shows remarkable similarities, both in stability and photophysical properties. Low temperature photophysical measurements for a Gd(III) complex were also used to gain insight into the electronic structure, and were found to agree with corresponding TD-DFT calculations for a model complex. A comparison of the high resolution Eu(III) emission spectra in solution and from single crystals also revealed a more symmetric coordination geometry about the metal ion in solution due to dynamic rotation of the observed solid state structure.

  15. Blue Emission in Proteins

    OpenAIRE

    Sarkar, Sohini; Sengupta, Abhigyan; Hazra, Partha; Mandal, Pankaj

    2014-01-01

    Recent literatures reported blue-green emission from amyloid fibril as exclusive signature of fibril formation. This unusual visible luminescence is regularly used to monitor fibril growth. Blue-green emission has also been observed in crystalline protein and in solution. However, the origin of this emission is not known exactly. Our spectroscopic study of serum proteins reveals that the blue-green emission is a property of protein monomer. Evidences suggest that semiconductor-like band struc...

  16. Refractive Index Tuning of Hybrid Materials for Highly Transmissive Luminescent Lanthanide Particle-Polymer Composites.

    Science.gov (United States)

    Kim, Paul; Li, Cheng; Riman, Richard E; Watkins, James

    2018-03-14

    High-refractive-index ZrO 2 nanoparticles were used to tailor the refractive index of a polymer matrix to match that of luminescent lanthanide-ion-doped (La 0.92 Yb 0.075 Er 0.005 F 3 ) light-emitting particles, thereby reducing scattering losses to yield highly transparent emissive composites. Photopolymerization of blends of an amine-modified poly(ether acrylate) oligomer and tailored quantities of ZrO 2 nanoparticles yielded optically transparent composites with tailored refractive indices between 1.49 and 1.69. By matching the refractive index of the matrix to that of La 0.92 Yb 0.075 Er 0.005 F 3 , composites with high transmittance (>85%) and low haze from the visible to infrared regions, bright 1530 nm optical emissions were achieved at solids loadings of La 0.92 Yb 0.075 Er 0.005 F 3 , ranging from 5 to 30 vol %. These optical results suggest that a hybrid matrix approach is a versatile strategy for the fabrication of functional luminescent optical composites of high transparency.

  17. Microwave synthesis of homogeneous and highly luminescent BCNO nanoparticles for the light emitting polymer materials

    Energy Technology Data Exchange (ETDEWEB)

    Iwasaki, Hideharu [Battery Materials Laboratory, Kurashiki Research Center, Kuraray Co., Ltd., 2045-1, Sakazu, Kurashiki, Okayama 710-0801 (Japan); Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739 8527 (Japan); Ogi, Takashi, E-mail: ogit@hiroshima-u.ac.jp [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739 8527 (Japan); Iskandar, Ferry [Department of Physics, Institute of Technology Bandung, Ganesha 10, Bandung 40132, West Java (Indonesia); Aishima, Kana; Okuyama, Kikuo [Department of Chemical Engineering, Graduate School of Engineering, Hiroshima University, 1-4-1 Kagamiyama, Higashi Hiroshima 739 8527 (Japan)

    2015-10-15

    Nano-sized boron carbon oxynitride (BCNO) phosphors around 50 nm containing no rare earth metal and free from color heterogeneity were synthesized from mixtures of boric acid, urea, and citric acid by microwave heating with substantially shorter reaction times and lower temperatures than in the conventional BCNO preparation method such as electric-furnace heating. The emission wavelength of the phosphors varied with the mixing ratio of raw materials and it was found that lowering the proportion of urea to boric acid or citric acid tended to increase the internal quantum yield and shorten the emission wavelength under excitation at 365 nm. It was also found for the first time that a light-emitting polymer could be synthesized from a mixture of the prepared BCNO nanoparticles and a polyvinyl alcohol. This polymer composite exhibited uniform dispersion and stabilization of the luminescence and had a high internal quantum yield of 54%, which was higher than that of the phosphor alone. - Highlights: • Nano-sized BCNO phosphor was synthesized via microwave heating. • BCNO nanophosphor has homogeneous and high luminescence. • Emission wavelength was tunable by changing the ratio of precursor components. • BCNO nanophosphor can be easily dispersed in a polyvinyl alcohol. • BCNO–polymer composite exhibited uniform high internal quantum yield.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2014-11-15

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

  19. Highly Luminescent, Water-Soluble Lanthanide Fluorobenzoates: Syntheses, Structures and Photophysics, Part I: Lanthanide Pentafluorobenzoates.

    Science.gov (United States)

    Kalyakina, Alena S; Utochnikova, Valentina V; Bushmarinov, Ivan S; Ananyev, Ivan V; Eremenko, Igor L; Volz, Daniel; Rönicke, Franziska; Schepers, Ute; Van Deun, Rik; Trigub, Alexander L; Zubavichus, Yan V; Kuzmina, Natalia P; Bräse, Stefan

    2015-12-01

    Highly luminescent, photostable, and soluble lanthanide pentafluorobenzoates have been synthesized and thoroughly characterized, with a focus on Eu(III) and Tb(III) complexes as visible emitters and Nd(III) , Er(III) , and Yb(III) complexes as infrared emitters. Investigation of the crystal structures of the complexes in powder form and as single crystals by using X-ray diffraction revealed five different structural types, including monomeric, dimeric, and polymeric. The local structure in different solutions was studied by using X-ray absorption spectroscopy. The photoluminescence quantum yields (PLQYs) of terbium and europium complexes were 39 and 15 %, respectively; the latter value was increased almost twice by using the heterometallic complex [Tb0.5 Eu0.5 (pfb)3 (H2 O)] (Hpfb=pentafluorobenzoic acid). Due to the effectively utilized sensitization strategy (pfb)(-) →Tb→Eu, a pure europium luminescence with a PLQY of 29 % was achieved. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. From Big Data to Big Displays High-Performance Visualization at Blue Brain

    KAUST Repository

    Eilemann, Stefan; Abdellah, Marwan; Antille, Nicolas; Bilgili, Ahmet; Chevtchenko, Grigory; Dumusc, Raphael; Favreau, Cyrille; Hernando, Juan; Nachbaur, Daniel; Podhajski, Pawel; Villafranca, Jafet; Schü rmann, Felix

    2017-01-01

    Blue Brain has pushed high-performance visualization (HPV) to complement its HPC strategy since its inception in 2007. In 2011, this strategy has been accelerated to develop innovative visualization solutions through increased funding and strategic

  1. Use of a highly sensitive two-dimensional luminescence imaging system to monitor endogenous bioluminescence in plant leaves

    Directory of Open Access Journals (Sweden)

    Flor-Henry Michel

    2004-11-01

    Full Text Available Abstract Background All living organisms emit spontaneous low-level bioluminescence, which can be increased in response to stress. Methods for imaging this ultra-weak luminescence have previously been limited by the sensitivity of the detection systems used. Results We developed a novel configuration of a cooled charge-coupled device (CCD for 2-dimensional imaging of light emission from biological material. In this study, we imaged photon emission from plant leaves. The equipment allowed short integration times for image acquisition, providing high resolution spatial and temporal information on bioluminescence. We were able to carry out time course imaging of both delayed chlorophyll fluorescence from whole leaves, and of low level wound-induced luminescence that we showed to be localised to sites of tissue damage. We found that wound-induced luminescence was chlorophyll-dependent and was enhanced at higher temperatures. Conclusions The data gathered on plant bioluminescence illustrate that the equipment described here represents an improvement in 2-dimensional luminescence imaging technology. Using this system, we identify chlorophyll as the origin of wound-induced luminescence from leaves.

  2. Li4SrCa(SiO4)2:Ce3+, a highly efficient near-UV and blue emitting orthosilicate phosphor

    International Nuclear Information System (INIS)

    Zhang, Jilin; Zhang, Weilu; Qiu, Zhongxian; Zhou, Wenli; Yu, Liping; Li, Zhiqiang; Lian, Shixun

    2015-01-01

    High quantum efficiency is a vital parameter of phosphors for practical application. An efficient near-UV and blue emitting phosphor Li 4 SrCa(SiO 4 ) 2 :Ce 3+ was synthesized by a traditional solid-state reaction, and luminescent properties were studied in detail. The Ce 3+ -activated phosphor can emit both a near-UV light centred at 345 nm and a blue light peaking at 420 nm when Ce 3+ occupies the Sr and Ca site, respectively. The internal quantum efficiency (IQE) of Li 4 SrCa(SiO 4 ) 2 :0.03Ce 3+ is as high as 97% under the excitation at 288 nm, while the external quantum efficiency (EQE) is 66%. The IQE and EQE values of Li 4 SrCa(SiO 4 ) 2 :0.03Ce 3+ under the excitation at 360 nm are 82% and 31%, respectively. - Highlights: • Phosphor Li 4 SrCa(SiO 4 ) 2 :Ce 3+ emits a near-UV (345 nm) and a blue light (420 nm). • Emission band at 345 nm originates from Ce 3+ on Sr site. • Emission band at 420 nm belongs to Ce 3+ on Ca site. • Internal quantum efficiency is 97% for Li 4 SrCa(SiO 4 ) 2 :0.03Ce 3+ excited at 288 nm

  3. Silver-induced reconstruction of an adeninate-based metal-organic framework for encapsulation of luminescent adenine-stabilized silver clusters.

    Science.gov (United States)

    Jonckheere, Dries; Coutino-Gonzalez, Eduardo; Baekelant, Wouter; Bueken, Bart; Reinsch, Helge; Stassen, Ivo; Fenwick, Oliver; Richard, Fanny; Samorì, Paolo; Ameloot, Rob; Hofkens, Johan; Roeffaers, Maarten B J; De Vos, Dirk E

    2016-05-21

    Bright luminescent silver-adenine species were successfully stabilized in the pores of the MOF-69A (zinc biphenyldicarboxylate) metal-organic framework, starting from the intrinsically blue luminescent bio-MOF-1 (zinc adeninate 4,4'-biphenyldicarboxylate). Bio-MOF-1 is transformed to the MOF-69A framework by selectively leaching structural adenine linkers from the original framework using silver nitrate solutions in aqueous ethanol. Simultaneously, bright blue-green luminescent silver-adenine clusters are formed inside the pores of the recrystallized MOF-69A matrix in high local concentrations. The structural transition and concurrent changes in optical properties were characterized using a range of structural, physicochemical and spectroscopic techniques (steady-state and time-resolved luminescence, quantum yield determination, fluorescence microscopy). The presented results open new avenues for exploring the use of MOFs containing luminescent silver clusters for solid-state lighting and sensor applications.

  4. High-resolution stratigraphy and multiple luminescence dating techniques to reveal the paleoseismic history of the central Dead Sea fault (Yammouneh fault, Lebanon)

    Science.gov (United States)

    Le Béon, Maryline; Tseng, Ya-Chu; Klinger, Yann; Elias, Ata; Kunz, Alexander; Sursock, Alexandre; Daëron, Mathieu; Tapponnier, Paul; Jomaa, Rachid

    2018-07-01

    Continuous sedimentation and detailed stratigraphy are key parameters for a complete paleo-earthquake record. Here, we present a new paleoseismological study across the main strike-slip fault branch of the Dead Sea fault in Lebanon. We aim to expand the current knowledge on local paleoseismicity and seismic behavior of strike-slip plate boundary faults and to explore the limitations of paleoseismology and dating methods. The trench, dug in the Jbab el-Homr basin, reveals a succession of remarkable, very thin (0.1 to 5 cm) palustrine and lacustrine layers, ruptured by at least 17 earthquakes. Absolute ages of 4 samples are obtained from three luminescence-dating techniques targeting fine-grain minerals. Blue-green stimulated luminescence (BGSL) on quartz and post-infrared infrared-stimulated luminescence at 225 °C on polymineral aliquots led to consistent ages, while ages from infrared-stimulated luminescence at 50 °C on polymineral aliquots appeared underestimated. The quartz BGSL ages are 26.9 ± 2.3 ka at 0.50 m depth and 30.8 ± 2.9 ka at 3.65 m depth. During this time period of 3.9 ka ([0; 9.1 ka]), 14 surface-rupturing events occurred with a mean return time of 280 years ([0; 650 years]) and probable clustering. This return time is much shorter than the 1127 ± 135 years return time previously determined at the Yammouneh site, located 30 km south. Although fault segmentation and temporal variations in the earthquake cycle remain possible causes for such different records, we argue that the high-resolution stratigraphy in Jbab is the main factor, enabling us to record small deformations related to smaller-magnitude events that may have been missed in the rougher strata of Yammouneh. Indeed, focusing only on larger events of Jbab, we obtain a mean return time of 720 years ([0; 1670 years]) that is compatible with the Yammouneh record.

  5. Optimizing Blue Persistent Luminescence in (Sr 1-δ Ba δ ) 2 MgSi 2 O 7: Eu 2+ ,Dy 3+ via Solid Solution for Use in Point-of-Care Diagnostics

    Energy Technology Data Exchange (ETDEWEB)

    Finley, Erin; Cobb, Angelica; Duke, Anna; Paterson, Andrew; Brgoch, Jakoah (Luminostics); (Houston)

    2016-11-04

    Inorganic persistent luminescent phosphors are an excellent class of optical reporters for enabling sensitive point-of-care diagnostics, particularly with smartphone-based biosensing devices in testing formats such as the lateral flow assay (LFA). Here, the development of persistent phosphors for this application is focused on the solid solution (Sr1-δBaδ)2MgSi2O7:Eu2+,Dy3+ (δ = 0, 0.125, 0.25, 0.375), which is prepared using a high-temperature solid-state reaction as confirmed by synchrotron X-ray powder diffraction. The substitution of barium for strontium enables control over the Eu2+ 5d-orbital crystal field splitting (CFS) as a tool for tuning the emission wavelength while maintaining luminescence lifetimes >9 min across the composition range. Thermoluminescence measurements of the solid solution provide evidence that trap states contribute to the persistent lifetimes with the trap depths also remaining constant as a function of composition. Time-gated luminescence images of these compounds are captured on a smartphone arranged in a layout to mimic a point-of-care test and demonstrate the viability of using these materials as optical reporters. Moreover, comparing the blue-emitting (Sr0.625Ba0.375)2MgSi2O7:Eu2+,Dy3+ and the green-emitting SrAl2O4:Eu2+,Dy3+ in a single LFA-type format shows these two compounds can be detected and resolved simultaneously, thereby permitting the development of a multiplexed LFA.

  6. NK sensitivity of neuroblastoma cells determined by a highly sensitive coupled luminescent method

    International Nuclear Information System (INIS)

    Ogbomo, Henry; Hahn, Anke; Geiler, Janina; Michaelis, Martin; Doerr, Hans Wilhelm; Cinatl, Jindrich

    2006-01-01

    The measurement of natural killer (NK) cells toxicity against tumor or virus-infected cells especially in cases with small blood samples requires highly sensitive methods. Here, a coupled luminescent method (CLM) based on glyceraldehyde-3-phosphate dehydrogenase release from injured target cells was used to evaluate the cytotoxicity of interleukin-2 activated NK cells against neuroblastoma cell lines. In contrast to most other methods, CLM does not require the pretreatment of target cells with labeling substances which could be toxic or radioactive. The effective killing of tumor cells was achieved by low effector/target ratios ranging from 0.5:1 to 4:1. CLM provides highly sensitive, safe, and fast procedure for measurement of NK cell activity with small blood samples such as those obtained from pediatric patients

  7. Regioselective aromatic substitution reactions of cyclometalated Ir(III) complexes: synthesis and photochemical properties of substituted Ir(III) complexes that exhibit blue, green, and red color luminescence emission.

    Science.gov (United States)

    Aoki, Shin; Matsuo, Yasuki; Ogura, Shiori; Ohwada, Hiroki; Hisamatsu, Yosuke; Moromizato, Shinsuke; Shiro, Motoo; Kitamura, Masanori

    2011-02-07

    In this manuscript, the regioselective halogenation, nitration, formylation, and acylation of Ir(tpy)(3) and Ir(ppy)(3) (tpy = 2-(4'-tolyl)pyridine and ppy = 2-phenylpyridine) and the subsequent conversions are described. During attempted bromination of the three methyl groups in fac-Ir(tpy)(3) using N-bromosuccinimide (NBS) and benzoyl peroxide (BPO), three protons at the 5'-position (p-position with respect to the C-Ir bond) of phenyl rings in tpy units were substituted by Br, as confirmed by (1)H NMR spectra, mass spectra, and X-ray crystal structure analysis. It is suggested that such substitution reactions of Ir complexes proceed via an ionic mechanism rather than a radical mechanism. UV-vis and luminescence spectra of the substituted Ir(III) complexes are reported. The introduction of electron-withdrawing groups such as CN and CHO groups at the 5'-position of tpy induces a blue shift of luminescence emission to about 480 nm, and the introduction of electron-donating groups such as an amino group results in a red shift to about 600 nm. A reversible change of emission for the 5'-amino derivative of Ir(tpy)(3), Ir(atpy)(3), between red and green occurs upon protonation and deprotonation.

  8. Suppressed speckle contrast of blue light emission out of white lamp with phosphors excited by blue laser diodes for high-brightness lighting applications

    Science.gov (United States)

    Kinoshita, Junichi; Ikeda, Yoshihisa; Takeda, Yuji; Ueno, Misaki; Kawasaki, Yoji; Matsuba, Yoshiaki; Heike, Atsushi

    2012-11-01

    The speckle contrast of blue light emission out of high-brightness white lamps using phosphors excited by InGaN/GaN blue laser diodes is evaluated as a measure of coherence. As a result, speckle contrast of as low as 1.7%, the same level as a blue light emitting diode, is obtained. This implies that the original blue laser light can be converted into incoherent light through lamp structures without any dynamic mechanisms. This unique speckle-free performance is considered to be realized by multiple scattering inside the lamp structure, the multi-longitudinal mode operation of the blue laser diodes, and the use of multiple laser diodes. Such almost-incoherent white lamps can be applied for general lighting without any nuisance of speckle noise and should be categorized as lamps rather than lasers in terms of laser safety regulation.

  9. Eu2+-doped Ba2GaB4O9Cl blue-emitting phosphor with high color purity for near-UV-pumped white light-emitting diodes

    Science.gov (United States)

    Gao, Zhiwen; Deng, Huajuan; Xue, Na; Jeong, Jung Hyun; Yu, Ruijin

    2018-01-01

    Eu2+-doped borate fluoride Ba2GaB4O9Cl was synthesized by the conventional high-temperature solid-state reaction. The crystal structure and luminescence properties of the phosphors, as well as their thermal luminescence quenching capabilities and CIE chromaticity coordinates were systematically investigated. Under the excitation at 340 nm, the phosphor exhibited an asymmetric broad-band blue emission with a peak at 445 nm, which is ascribed to the 4f-5d transition of Eu2+. It was further proved that energy transfer among the nearest neighbor ions is the major mechanism for concentration quenching of Eu2+ in Ba2-xGaB4O9Cl:xEu2+ phosphors. The luminescence quenching temperature is 432 K. The CIE color coordinates are very close to those of BaMgAl10O17:Eu2+ (BAM). All the properties indicated that the blue-emitting Ba2GaB4O9Cl:Eu2+ phosphor has potential application in white LEDs.

  10. Highly efficient greenish-blue platinum-based phosphorescent organic light-emitting diodes on a high triplet energy platform

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Y. L., E-mail: yilu.chang@mail.utoronto.ca; Gong, S., E-mail: sgong@chem.utoronto.ca; White, R.; Lu, Z. H., E-mail: zhenghong.lu@utoronto.ca [Department of Materials Science and Engineering, University of Toronto, 184 College St., Toronto, Ontario M5S 3E4 (Canada); Wang, X.; Wang, S., E-mail: wangs@chem.queensu.ca [Department of Chemistry, Queen' s University, 90 Bader Lane, Kingston, Ontario K7L 3N6 (Canada); Yang, C. [Department of Chemistry, Wuhan University, Wuhan 430072 (China)

    2014-04-28

    We have demonstrated high-efficiency greenish-blue phosphorescent organic light-emitting diodes (PHOLEDs) based on a dimesitylboryl-functionalized C^N chelate Pt(II) phosphor, Pt(m-Bptrz)(t-Bu-pytrz-Me). Using a high triplet energy platform and optimized double emissive zone device architecture results in greenish-blue PHOLEDs that exhibit an external quantum efficiency of 24.0% and a power efficiency of 55.8 lm/W. This record high performance is comparable with that of the state-of-the-art Ir-based sky-blue organic light-emitting diodes.

  11. Luminescence and scintillation of Eu.sup.2+./sup.-doped high silica glass

    Czech Academy of Sciences Publication Activity Database

    Chewpraditkul, W.; Chen, D.; Yu, B.; Zhang, Q.; Shen, Y.; Nikl, Martin; Kučerková, Romana; Beitlerová, Alena; Wanarak, C.; Phunpueok, A.

    2011-01-01

    Roč. 5, č. 1 (2011), s. 40-42 ISSN 1862-6254 R&D Projects: GA MŠk(CZ) ME10084 Institutional research plan: CEZ:AV0Z10100521 Keywords : glasses * Eu 2+ * luminescence * scintillation * time-resolved luminescence * porous materials Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.218, year: 2011

  12. Temperature dependence of luminescence for different surface flaws in high purity silica glass

    International Nuclear Information System (INIS)

    Fournier, J.; Grua, P.; Neauport, J.; Fargin, E.; Jubera, V.; Talaga, D.; Del Guerzo, A.; Raffy, G.; Jouannigot, S.

    2013-01-01

    In situ temperature dependence of the Photoluminescence under 325 nm irradiation is used to investigate defect populations existing in different surface flaws in high purity fused silica. Five photoluminescence bands peaking at 1.9, 2.1, 2.3, 2.63 and 3.11 eV have been detected in the spectral area ranging from 1.6 up to 3.6 eV. The Gaussian deconvolution of spectra allows dividing the five luminescence bands in two categories. The former corresponds to bands showing a significant intensity enhancement while temperature decreases; the latter corresponds to bands remaining insensitive to the temperature evolution. Such a behavior brings new information on defects involved in laser damage mechanism at 351 nm in nanosecond regime. (authors)

  13. Fabrication of highly luminescent InP/Cd and InP/CdS quantum dots

    International Nuclear Information System (INIS)

    Park, Jaehyun; Kim, Sunghoon; Kim, Sungwoo; Yu, Seung Tack; Lee, Bunyeoul; Kim, Sang-Wook

    2010-01-01

    Highly luminescent InP/Cd and InP/CdS core-shell QDs were fabricated by sequential addition of cadmium acetylacetonate and dodecanethiol to InP core solutions, which showed a red-shift in absorption and emission. ICP measurement revealed the existence of cadmium and TEM images showed the increased size of InP/CdS QDs. PXRD data identified zinc blend structures of InP and InP/CdS QDs, which indexed to the (1 1 1), (2 2 0) and (3 1 1) planes. The slight shift of peaks between InP and InP/CdS QDs can demonstrate the existence of CdS shell structures.

  14. A novel stable 3D luminescent uranyl complex for highly efficient and sensitive recognition of Ru3+ and biomolecules

    Science.gov (United States)

    Tian, Hong-Hong; Chen, Liang-Ting; Zhang, Rong-Lan; Zhao, Jian-She; Liu, Chi-Yang; Weng, Ng Seik

    2018-02-01

    A novel highly stable 3D luminescent uranyl coordination polymer, namely {[UO2(L)]·DMA}n (1), was assembled with uranyl salt and a glycine-derivative ligand [6-(carboxymethyl-amino)-4-oxo-4,5-dihydro-[1,3,5]triazin-2-ylamino]-acetic acid (H2L) under solvothermal reaction. Besides, It was found that complex 1 possesses excellent luminescent properties, particularly the efficient selectivity and sensitivity in the recognition of Ru3+, biomacromolecule bovine serum albumin (BSA), biological small molecules dopamine (DA), ascorbic acid (AA) and uric acid (UA) in the water solution based on a "turn-off" mechanism. Accordingly, the luminescent explorations also demonstrated that complex 1 could be acted as an efficient luminescent probe with high quenching efficiency and low detection limit for selectively detecting Ru3+ and biomolecules (DA, AA, UA and BSA). It was noted that the framework structure of complex 1 still remains highly stable after quenching, which was verified by powder X-ray diffraction (PXRD).

  15. Kinetics of infrared stimulated luminescence from feldspars

    DEFF Research Database (Denmark)

    Jain, Mayank; Sohbati, Reza; Guralnik, Benny

    2015-01-01

    thermal and optical, of the infrared stimulated luminescence signal from feldspar. Based on the application of this model, it is concluded that different infra-red stimulated luminescence emissions (UV, blue, yellow and far-red) follow the same kinetics, and, therefore, involve participation of the same...

  16. Pure zinc sulfide quantum dot as highly selective luminescent probe for determination of hazardous cyanide ion

    International Nuclear Information System (INIS)

    Shamsipur, Mojtaba; Rajabi, Hamid Reza

    2014-01-01

    A rapid and simple fluorescence method is presented for selective and sensitive determination of hazardous cyanide ion in aqueous solution based on functionalized zinc sulfide (ZnS) quantum dot (QD) as luminescent prob. The ultra-small ZnS QDs were synthesized using a chemical co-precipitation method in the presence of 2-mercaptoethanol (ME) as an efficient capping agent. The prepared pure ZnS QDs was applied as an optical sensor for determination of cyanide ions in aqueous solutions. ZnS nanoparticles have exhibited a strong fluorescent emission at about 424 nm. The fluorescence intensity of QDs is linearly proportional to the cyanide ion concentration in the range 2.44 × 10 −6 to 2.59 × 10 −5 M with a detection limit of 1.70 × 10 −7 M at pH 11. The designed fluorescent sensor possesses remarkable selectivity for cyanide ion over other anions such as Cl − , Br − , F − , I − , IO 3 − , ClO 4 − , BrO 3 − , CO 3 2− , NO 2 − , NO 3 − , SO 4 2− , S 2 O 4 2− , C 2 O 4 2− , SCN − , N 3 − , citrate and tartarate with negligible influences on the cyanide detection by fluorescence spectroscopy. - Highlights: • Preparation of functionalized ZnS quantum dots in aqueous media • Highly selective quantum dot based luminescent probe for determination of cyanide • Fast and sensitive determination of hazardous CN − by fluorescence quenching

  17. Pure zinc sulfide quantum dot as highly selective luminescent probe for determination of hazardous cyanide ion

    Energy Technology Data Exchange (ETDEWEB)

    Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com [Department of Chemistry, Razi University, Kermanshah (Iran, Islamic Republic of); Rajabi, Hamid Reza, E-mail: h.rajabi@mail.yu.ac.ir [Chemistry Department, Yasouj University, Yasouj 75918-74831 (Iran, Islamic Republic of)

    2014-03-01

    A rapid and simple fluorescence method is presented for selective and sensitive determination of hazardous cyanide ion in aqueous solution based on functionalized zinc sulfide (ZnS) quantum dot (QD) as luminescent prob. The ultra-small ZnS QDs were synthesized using a chemical co-precipitation method in the presence of 2-mercaptoethanol (ME) as an efficient capping agent. The prepared pure ZnS QDs was applied as an optical sensor for determination of cyanide ions in aqueous solutions. ZnS nanoparticles have exhibited a strong fluorescent emission at about 424 nm. The fluorescence intensity of QDs is linearly proportional to the cyanide ion concentration in the range 2.44 × 10{sup −6} to 2.59 × 10{sup −5} M with a detection limit of 1.70 × 10{sup −7} M at pH 11. The designed fluorescent sensor possesses remarkable selectivity for cyanide ion over other anions such as Cl{sup −}, Br{sup −}, F{sup −}, I{sup −}, IO{sub 3}{sup −}, ClO{sub 4}{sup −}, BrO{sub 3}{sup −}, CO{sub 3}{sup 2−}, NO{sub 2}{sup −}, NO{sub 3}{sup −}, SO{sub 4}{sup 2−}, S{sub 2}O{sub 4}{sup 2−}, C{sub 2}O{sub 4}{sup 2−}, SCN{sup −}, N{sub 3}{sup −}, citrate and tartarate with negligible influences on the cyanide detection by fluorescence spectroscopy. - Highlights: • Preparation of functionalized ZnS quantum dots in aqueous media • Highly selective quantum dot based luminescent probe for determination of cyanide • Fast and sensitive determination of hazardous CN{sup −} by fluorescence quenching.

  18. An alkaline one-pot reaction to synthesize luminescent Eu-BTC MOF nanorods, highly pure and water-insoluble, under room conditions

    Energy Technology Data Exchange (ETDEWEB)

    Medina-Velazquez, D. Y., E-mail: dyolotzin@correo.azc.uam.mx; Alejandre-Zuniga, B. Y.; Loera-Serna, S.; Ortiz, E. M. [Universidad Autónoma Metropolitana-Azcapotzalco, División de Ciencias Básicas e Ingeniería (Mexico); Morales-Ramirez, A. de J. [CIITEC IPN, Instituto Politécnico Nacional (Mexico); Garfias-Garcia, E. [Universidad Autónoma Metropolitana-Azcapotzalco, División de Ciencias Básicas e Ingeniería (Mexico); Garcia-Murillo, A. [CIITEC IPN, Instituto Politécnico Nacional (Mexico); Falcony, C. [Centro de Investigación y Estudios Avanzados, Departamento de Física (Mexico)

    2016-12-15

    The increasing demand for optoelectronic devices requires the development of luminescent materials with high luminescence efficiency and low energy demands, and the metalorganic frameworks (MOFs) with lanthanides ions offer great potential in this area. The metalorganic materials provide properties of flexibility, low density, low-cost methods of synthesis, and insolubility in water, which gives them an advantage over traditional phosphors. In this study, a benzenetricarboxylate ligand (BTC) with a Eu{sup 3+} MOF was synthesized, and its structural and luminescent properties were measured. The metalorganic compound was generated in a one-pot reaction from europium nitrate and trimesic acid precursors. Through characterization by X-ray diffraction powder, infrared spectroscopy, SEM structural characterization, and luminescent spectroscopy, the formation of Europium benzenetricarboxylate (Eu-BTC) MOF nanorods was tested and the calculated value was in the range of 30–60 nm. A red luminescent emission with high intensity was observed for all the procedures.

  19. Highly sensitive luminescent sensor for cyanide ion detection in aqueous solution based on PEG-coated ZnS nanoparticles.

    Science.gov (United States)

    Mehta, Surinder K; Salaria, Khushboo; Umar, Ahmad

    2013-03-15

    Using polyethylene glycol (PEG) coated ZnS nanoparticles (NPs), a novel and highly sensitive luminescent sensor for cyanide ion detection in aqueous solution has been presented. ZnS NPs have been used to develop efficient luminescence sensor which exhibits high reproducibility and stability with the lowest limit of detection of 1.29×10(-6) mol L(-1). The observed limit of detection of the fabricated sensor is ~6 times lower than maximum value of cyanide permitted by United States Environmental Protection Agency for drinking water (7.69×10(-6) mol L(-1)). The interfering studies show that the developed sensor possesses good selectivity for cyanide ion even in presence of other coexisting ions. Importantly, to the best of our knowledge, this is the first report which demonstrates the utilization of PEG- coated ZnS NPs for efficient luminescence sensor for cyanide ion detection in aqueous solution. This work demonstrates that rapidly synthesized ZnS NPs can be used to fabricate efficient luminescence sensor for cyanide ion detection. Copyright © 2013 Elsevier B.V. All rights reserved.

  20. Blue and green emissions with high color purity from nanocrystalline Ca2Gd8Si6O26:Ln (Ln = Tm or Er) phosphors

    International Nuclear Information System (INIS)

    Seeta Rama Raju, G.; Park, Jin Young; Jung, Hong Chae; Pavitra, E.; Moon, Byung Kee; Jeong, Jung Hyun; Yu, Jae Su; Kim, Jung Hwan; Choi, Haeyoung

    2011-01-01

    Graphical abstract: Highlights: → Nanocrystalline Ca 2 Gd 8 Si 6 O 26 (CGS):Tm 3+ and CGS:Er 3+ phosphors were prepared by solvothermal reaction method. → The visible luminescence properties of phosphors were investigated by exciting with ultraviolet (UV) or near-UV light and low voltage electron beam (0.5-5 kV). → The photoluminescence spectra of CGS:Tm 3+ under 359 nm excitation and CGS:Er 3+ under 380 nm excitation showed the strong blue ( 1 D 2 → 3 F 4 at 456 nm) and green ( 4 S 3/2 → 4 I 15/2 at 550 nm) colors with the color purity 87% and 96%, respectively → The low accelerating voltage cathodoluminescence spectra of CGS:Tm 3+ and CGS:Er 3+ showed the strong blue and green emissions with the high color purity 95% and 96%, respectively. → The obtained results are hint at the promising applications to produce high quality LEDs and FED devices. - Abstract: Blue and green light emissive nanocrystalline Ca 2 Gd 8 Si 6 O 26 (CGS):Tm 3+ and CGS:Er 3+ phosphors with high color purity were prepared by solvothermal reaction method. The structural and morphological properties of these phosphors were evaluated by the powder X-ray diffraction (XRD) and scanning electron microscopy, respectively. From the XRD results, Tm 3+ :CGS and Er 3+ :CGS phosphors had the characteristic peaks of oxyapatite in the hexagonal lattice structure. The visible luminescence properties of phosphors were obtained by ultraviolet (UV) or near-UV light and low voltage electron beam (0.5-5 kV) excitation. The photoluminescence and cathodoluminescence properties were investigated by changing the variation of Tm 3+ or Er 3+ concentrations and the acceleration voltage, respectively. The CGS:Tm 3+ phosphors exhibited the blue emission due to 1 D 2 → 3 F 4 transition, while the CGS:Er 3+ phosphors showed the green emission due to 4 S 3/2 → 4 I 15/2 transition. The color purity and chromaticity coordinates of the fabricated phosphors are comparable to or better than those of standard

  1. Achieving blue luminescence of Alq3 through the pull-push effect of the electron-withdrawing and electron-donating substituents

    International Nuclear Information System (INIS)

    Shi Minmin; Lin Jiajun; Shi Yuewen; Ouyang Mi; Wang Mang; Chen Hongzheng

    2009-01-01

    A novel blue-emissive Alq 3 derivative, tris-(4-methyl-6-fluoro-8-hydroxyquinoline) aluminum (6), has been designed and prepared. Because the strong electronegative F atom at 6-position lowers the HOMO significantly and the weak electron-donating methyl group at 4-position retains the drop of the LUMO, the band gap of 6 is broadened, and a blue-shift by 53 nm of the emission peak (λ em ) with substantially enhanced intensity is demonstrated when compared to that of Alq 3 . It is also found that 6 possesses good thermal stability and solubility in common solvents. Through theoretical simulations of the frontier orbitals, it is disclosed that 6's λ em can be blue-shifted further if methyl is replaced with a stronger electron-donating substituent, such as methoxy or N,N'-dimethylamino group.

  2. Luminescent zinc(ii) and copper(i) complexes for high-performance solution-processed monochromic and white organic light-emitting devices.

    Science.gov (United States)

    Cheng, Gang; So, Gary Kwok-Ming; To, Wai-Pong; Chen, Yong; Kwok, Chi-Chung; Ma, Chensheng; Guan, Xiangguo; Chang, Xiaoyong; Kwok, Wai-Ming; Che, Chi-Ming

    2015-08-01

    The synthesis and spectroscopic properties of luminescent tetranuclear zinc(ii) complexes of substituted 7-azaindoles and a series of luminescent copper(i) complexes containing 7,8-bis(diphenylphosphino)-7,8-dicarba- nido -undecaborate ligand are described. These complexes are stable towards air and moisture. Thin film samples of the luminescent copper(i) complexes in 2,6-dicarbazolo-1,5-pyridine and zinc(ii) complexes in poly(methyl methacrylate) showed emission quantum yields of up to 0.60 (for Cu-3 ) and 0.96 (for Zn-1 ), respectively. Their photophysical properties were examined by ultrafast time-resolved emission spectroscopy, temperature dependent emission lifetime measurements and density functional theory calculations. Monochromic blue and orange solution-processed OLEDs with these Zn(ii) and Cu(i) complexes as light-emitting dopants have been fabricated, respectively. Maximum external quantum efficiency (EQE) of 5.55% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.16, 0.19) were accomplished with the optimized Zn-1 -OLED while these values were, respectively 15.64% and (0.48, 0.51) for the optimized Cu-3 -OLED. Solution-processed white OLEDs having maximum EQE of 6.88%, CIE coordinates of (0.42, 0.44), and colour rendering index of 81 were fabricated by using these luminescent Zn(ii) and Cu(i) complexes as blue and orange light-emitting dopant materials, respectively.

  3. Luminescence nanothermometry

    Science.gov (United States)

    Jaque, Daniel; Vetrone, Fiorenzo

    2012-07-01

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

  4. Highly efficient deep-blue organic light emitting diode with a carbazole based fluorescent emitter

    Science.gov (United States)

    Sahoo, Snehasis; Dubey, Deepak Kumar; Singh, Meenu; Joseph, Vellaichamy; Thomas, K. R. Justin; Jou, Jwo-Huei

    2018-04-01

    High efficiency deep-blue emission is essential to realize energy-saving, high-quality display and lighting applications. We demonstrate here a deep-blue organic light emitting diode using a novel carbazole based fluorescent emitter 7-[4-(diphenylamino)phenyl]-9-(2-ethylhexyl)-9H-carbazole-2-carbonitrile (JV234). The solution processed resultant device shows a maximum luminance above 1,750 cd m-2 and CIE coordinates (0.15,0.06) with a 1.3 lm W-1 power efficiency, 2.0 cd A-1 current efficiency, and 4.1% external quantum efficiency at 100 cd m-2. The resulting deep-blue emission enables a greater than 100% color saturation. The high efficiency may be attributed to the effective host-to-guest energy transfer, suitable device architecture facilitating balanced carrier injection and low doping concentration preventing efficiency roll-off caused by concentration quenching.

  5. Manufacturing Gender Inequality in the New Economy: High School Training for Work in Blue-Collar Communities.

    Science.gov (United States)

    Sutton, April; Bosky, Amanda; Muller, Chandra

    2016-08-01

    Tensions between the demands of the knowledge-based economy and remaining, blue-collar jobs underlie renewed debates about whether schools should emphasize career and technical training or college-preparatory curricula. We add a gendered lens to this issue, given the male-dominated nature of blue-collar jobs and women's greater returns to college. Using the ELS:2002, this study exploits spatial variation in school curricula and jobs to investigate local dynamics that shape gender stratification. Results suggest a link between high school training and jobs in blue-collar communities that structures patterns of gender inequality into early adulthood. Although high school training in blue-collar communities reduced both men's and women's odds of four-year college enrollment, it had gender-divergent labor market consequences. Men in blue-collar communities took more blue-collar courses, had higher rates of blue-collar employment, and earned similar wages relative to otherwise comparable men from non-blue-collar communities. Women were less likely to work and to be employed in professional occupations, and they suffered severe wage penalties relative to their male peers and women from non-blue-collar communities. These relationships were due partly to high schools in blue-collar communities offering more blue-collar and fewer advanced college-preparatory courses. This curricular tradeoff may benefit men, but it appears to disadvantage women.

  6. Synthesis of highly luminescent Mn:ZnSe/ZnS nanocrystals in aqueous media

    International Nuclear Information System (INIS)

    Fang Zheng; Wu Ping; Zhong Xinhua; Yang Yongji

    2010-01-01

    High-quality water-dispersible Mn 2+ -doped ZnSe core/ZnS shell (Mn:ZnSe/ZnS) nanocrystals have been synthesized directly in aqueous media. Overcoating a high bandgap ZnS shell around the Mn:ZnSe cores can bring forward an efficient energy transfer from the ZnSe host nanocrystals to the dopant Mn. The quantum yields of the dopant Mn photoluminescence in the as-prepared water-soluble Mn:ZnSe/ZnS core/shell nanocrystals can be up to 35 ± 5%. The optical features and structure of the obtained Mn:ZnSe/ZnS core/shell nanocrystals have been characterized by UV-vis, PL spectroscopy, TEM, XRD and ICP elementary analysis. The influences of various experimental variables, including the Mn concentration, the Se/Zn molar ratio as well as the kind and amount of capping ligand used in the core production and shell deposition process, on the luminescent properties of the obtained Mn:ZnSe/ZnS nanocrystals have been systematically investigated.

  7. A portable luminescence dating instrument

    DEFF Research Database (Denmark)

    Kook, M.H.; Murray, A.S.; Lapp, Torben

    2011-01-01

    We describe a portable luminescence reader suitable for use in remote localities in the field. The instrument weighs about 8kg and is based around a 30mm bialkali photomultiplier detecting signals through a glass filter centered on 340nm. Stimulation is by 470nm blue LEDs (24W in total) operating...

  8. Advances in luminescence instrument systems

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Bulur, E.; Duller, G.A.T.

    2000-01-01

    We report on recent advances in the development of luminescence measurement systems and techniques at Riso. These include: (1) optical stimulation units based on new-generation powerful blue light (470 nm) emitting diodes providing up to 28 mW/cm(2) for OSL measurements; (2) an infrared (830 nm...

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

    Science.gov (United States)

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

    2017-11-01

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

  10. High Power, Thermally Optimized Blue Laser for Lidar, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — To enable widespread and rapid airborne bathymetric lidar to adequate depths in many ocean regions a low-cost, rugged, and high energy pulsed laser source must be...

  11. High Power, Thermally Optimized Blue Laser for Lidar, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — To enable widespread and rapid airborne bathymetric lidar to adequate depths in many ocean regions a low-cost, rugged, and high energy pulsed laser source must be...

  12. Highly Luminescent Dual Mode Polymeric Nanofiber-Based Flexible Mat for White Security Paper and Encrypted Nanotaggant Applications.

    Science.gov (United States)

    Gangwar, Amit Kumar; Gupta, Ashish; Kedawat, Garima; Kumar, Pawan; Singh, Bhanu Pratap; Singh, Nidhi; Srivastava, Avanish K; Dhakate, Sanjay R; Gupta, Bipin Kumar

    2018-05-23

    Increasing counterfeiting of important data, currency, stamp papers, branded products etc., has become a major security threat which could lead to serious damage to the global economy. Consequences of such damage are compelling for researchers to develop new high-end security features to address full-proof solutions. Herein, we report a dual mode flexible highly luminescent white security paper and nanotaggants composed of nanophosphors incorporated in polymer matrix to form a nanofiber-based mat for anti-counterfeiting applications. The dual mode nanofibers are fabricated by electrospinning technique by admixing the composite of NaYF 4 :Eu 3+ @NaYF 4 :Yb 3+ , Er 3+ nanophosphors in the polyvinyl alcohol solution. This flexible polymer mat derived from nanofibers appears white in daylight, while emitting strong red (NaYF 4 :Eu 3+ ) and green (NaYF 4 :Yb 3+ , Er 3+ ) colors at excitation wavelengths of 254 nm and 980 nm, respectively. These luminescent nanofibers can also be encrypted as a new class of nanotaggants to protect confidential documents. These obtained results suggest that highly luminescent dual mode polymeric nanofiber-based flexible white security paper and nanotaggants could offer next-generation high-end unique security features against counterfeiting. © 2018 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Microwave-assisted synthesis of highly luminescent N- and S-co-doped carbon dots as a ratiometric fluorescent probe for levofloxacin.

    Science.gov (United States)

    Li, Huiyu; Xu, Yuan; Ding, Jie; Zhao, Li; Zhou, Tianyu; Ding, Hong; Chen, Yanhua; Ding, Lan

    2018-01-10

    Uniform N- and S-co-doped carbon dots (NSCDs) with fluorescence quantum yields of up to 64% were synthesized via a one-step microwave-assisted method. Ammonium citrate and L-cysteine act as precursors, and synthesis is completed in 2.5 min using a 750 W microwave oven to give a 62% yield. The NSCDs show bright blue fluorescence (with excitation/emission peaks at 353/426 nm) and have narrow size distribution. On exposure to levofloxacin (LEV), the emission maximum shifts to 499 nm. This effect was used to design ratiometric (2-wavelength) assays for LEV. The fluorometric method (based on measurement of the fluorescence intensity ratio at 499 and 426 nm) has a detection limit of 5.1 μg·L -1 (3σ/k) and a linear range that extends from 0.01 to 70 mg·L -1 . The method was applied to the determination of LEV in three kinds of spiked water samples and has recoveries in the range from 98.6 to 106.8%. The fluorescent probe described here is highly selective and sensitive. Graphical Abstract Highly luminescent N- and S-co-doped carbon dots were synthesized using AC (ammonium citrate) and Cys (L-cysteine) by microwave-assisted method, and were applied to the visual and ratiometric fluorescence determination of LEV (levofloxacin).

  14. FPGA Implementation of Blue Whale Calls Classifier Using High-Level Programming Tool

    Directory of Open Access Journals (Sweden)

    Mohammed Bahoura

    2016-02-01

    Full Text Available In this paper, we propose a hardware-based architecture for automatic blue whale calls classification based on short-time Fourier transform and multilayer perceptron neural network. The proposed architecture is implemented on field programmable gate array (FPGA using Xilinx System Generator (XSG and the Nexys-4 Artix-7 FPGA board. This high-level programming tool allows us to design, simulate and execute the compiled design in Matlab/Simulink environment quickly and easily. Intermediate signals obtained at various steps of the proposed system are presented for typical blue whale calls. Classification performances based on the fixed-point XSG/FPGA implementation are compared to those obtained by the floating-point Matlab simulation, using a representative database of the blue whale calls.

  15. Pure zero-dimensional Cs4PbBr6 single crystal rhombohedral microdisks with high luminescence and stability.

    Science.gov (United States)

    Zhang, Haihua; Liao, Qing; Wu, Yishi; Chen, Jianwei; Gao, Qinggang; Fu, Hongbing

    2017-11-08

    Zero-dimensional (0D) perovskite Cs 4 PbBr 6 has been speculated to be an efficient solid-state emitter, exhibiting strong luminescense on achieving quantum confinement. Although several groups have reported strong green luminescence from Cs 4 PbBr 6 powders and nanocrystals, doubts that the origin of luminescence comes from Cs 4 PbBr 6 itself or CsPbBr 3 impurities have been a point of controversy in recent investigations. Herein, we developed a facile one-step solution self-assembly method to synthesize pure zero-dimensional rhombohedral Cs 4 PbBr 6 micro-disks (MDs) with a high PLQY of 52% ± 5% and photoluminescence full-width at half maximum (FWHM) of 16.8 nm. The obtained rhombohedral MDs were high quality single-crystalline as demonstrated by XRD and SAED patterns. We demonstrated that Cs 4 PbBr 6 MDs and CsPbBr 3 MDs were phase-separated from each other and the strong green emission comes from Cs 4 PbBr 6 . Power and temperature dependence spectra evidenced that the observed strong green luminescence of pure Cs 4 PbBr 6 MDs originated from direct exciton recombination in the isolated octahedra with a large binding energy of 303.9 meV. Significantly, isolated PbBr 6 4- octahedra separated by a Cs + ion insert in the crystal lattice is beneficial to maintaining the structural stability, depicting superior thermal and anion exchange stability. Our study provides an efficient approach to obtain high quality single-crystalline Cs 4 PbBr 6 MDs with highly efficient luminescence and stability for further optoelectronic applications.

  16. High-pressure luminescence spectroscopy of EuAl2O4 phosphor

    International Nuclear Information System (INIS)

    Zorenko, Yu.; Gorbenko, V.; Grinberg, M.; Turos-Matysiak, R.; Kuklinski, B.

    2007-01-01

    EuAl 2 O 4 powder phosphor was prepared by solid-state reaction of EuO and Al 2 O 3 oxides in vacuum. The influence of conditions of preparation on spectral lineshape of Eu 2+ emission was analyzed. It was found that the fluorescence spectra of vacuum-prepared EuAl 2 O 4 samples at 300 K present the superposition of three bands peaked at 430, 500 and 528 nm, corresponding to the 4f 6 5d 1 →4f 7 ( 8 S 7/2 ) transition of Eu 2+ ions in the different sites of EuAl 2 O 4 lattice. The luminescence of Eu 2+ centers in EuAl 2 O 4 host was also studied using the high-pressure spectroscopy up to 67 kbar. It was found that the bright green-yellow fluorescence of EuAl 2 O 4 at 300 K in the band peaked at 520-530nm range can be presented by superposition of two Gaussian sub-bands. The different pressure shifts -23 and -27cm -1 /kbar for two sub-bands were found. Such a structure of the emission spectrum was attributed to the existence of two different Eu 2+ centers in the Eu II 2+ sites of EuAl 2 O 4 lattice with higher coordination number

  17. Highly efficient luminescent solar concentrators based on earth-abundant indirect-bandgap silicon quantum dots

    Science.gov (United States)

    Meinardi, Francesco; Ehrenberg, Samantha; Dhamo, Lorena; Carulli, Francesco; Mauri, Michele; Bruni, Francesco; Simonutti, Roberto; Kortshagen, Uwe; Brovelli, Sergio

    2017-02-01

    Building-integrated photovoltaics is gaining consensus as a renewable energy technology for producing electricity at the point of use. Luminescent solar concentrators (LSCs) could extend architectural integration to the urban environment by realizing electrode-less photovoltaic windows. Crucial for large-area LSCs is the suppression of reabsorption losses, which requires emitters with negligible overlap between their absorption and emission spectra. Here, we demonstrate the use of indirect-bandgap semiconductor nanostructures such as highly emissive silicon quantum dots. Silicon is non-toxic, low-cost and ultra-earth-abundant, which avoids the limitations to the industrial scaling of quantum dots composed of low-abundance elements. Suppressed reabsorption and scattering losses lead to nearly ideal LSCs with an optical efficiency of η = 2.85%, matching state-of-the-art semi-transparent LSCs. Monte Carlo simulations indicate that optimized silicon quantum dot LSCs have a clear path to η > 5% for 1 m2 devices. We are finally able to realize flexible LSCs with performances comparable to those of flat concentrators, which opens the way to a new design freedom for building-integrated photovoltaics elements.

  18. A novel high color purity blue-emitting phosphor: CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Li, Jiangong, E-mail: lijiangong01@gmail.com [Department of Electronic Science and Engineering, Huanghuai University, Zhumadian 463000 (China); Yan, Huifang [Department of Foreign Languages and Literature, Huanghuai University, Zhumadian 463000 (China); Yan, Fengmei [Department of Chemistry and Chemical Engineering, Huanghuai University, Zhumadian 463000 (China)

    2016-07-15

    Graphical abstract: - Highlights: • A series of Tm{sup 3+}-doped CaBi{sub 2}B{sub 2}O{sub 7} blue-emitting phosphors were prepared. • The optimum doping content of Tm{sup 3+} ions was found. • The critical distance and concentration quenching mechanism was discussed. • The color purity of as prepared sample was analyzed and compared. - Abstract: A series of Tm{sup 3+}-doped CaBi{sub 2−x}B{sub 2}O{sub 7}:xTm{sup 3+} (0.02 ≤ x ≤ 0.12) blue-emitting phosphors with high color purity were prepared by solid-state reaction method. The crystal structure and luminescence properties of the as-prepared phosphors were studied. This phosphor shows a satisfactory blue performance (peak at 453 nm) due to the {sup 1}D{sub 2} → {sup 3}F{sub 4} transition of Tm{sup 3+} excited by 357 nm light. Investigation of Tm{sup 3+} content dependent emission spectra indicates that x = 0.04 is the optimum doping content of Tm{sup 3+} ions in the CaBi{sub 2}B{sub 2}O{sub 7} host. The critical distance and the concentration quenching mechanism were also investigated. In particular, the color purity of as prepared sample was analyzed and the result shows that the color purity of CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+} is higher than the commercial blue phosphor BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} (BAM:Eu{sup 2+}) and the latest reported Tm{sup 3+} doped blue phosphors. The present work suggests that the CaBi{sub 2}B{sub 2}O{sub 7}:Tm{sup 3+} phosphor is a potential blue-emitting candidate for the application in the near-UV WLEDs.

  19. Luminescent properties of Mg3Ca3(PO4)4: Eu2+ blue-emitting phosphor for white light emitting diodes

    International Nuclear Information System (INIS)

    Li Yinqun; Deng Degang; Wang Qian; Li Gaofeng; Hua Youjie; Jia Guohua; Huang Lihui; Zhao Shilong; Wang Huanping; Li Chenxia; Xu Shiqing

    2012-01-01

    A blue-emitting phosphor, Eu 2+ -activated Mg 3 Ca 3 (PO 4 ) 4 phosphor was synthesized by conventional solid-state reaction. X-ray powder diffraction (XRD) analysis confirmed the phase formation. Photoluminescence (PL) results showed that Mg 3 Ca 3 (PO 4 ) 4 : Eu 2+ could be efficiently excited by UV–visible light from 250 to 430 nm, which matched well with the emission wavelengths of near-UV and UV LED chips. The effects of the doped-Eu 2+ concentration in Mg 3 Ca 3 (PO 4 ) 4 : Eu 2+ on the PL were also investigated. The result reveals that Mg 3 Ca 3 (PO 4 ) 4 : Eu 2+ is a potential blue-emitting phosphor for white LEDs. - Graphical Abstract: The excitation spectra show a broad peak from 250 to 430 nm, which means Mg 3 Ca 3 (PO 4 ) 4 : Eu 2+ phosphor can be suitable for application in white LEDs excited by the near-UV and UV LEDs. The emission spectrum peaked at 456 nm with the full-width half-maximum (FWHM) of 102 nm is attributed to the 4f 6 5d 1 –4f 7 transition of the Eu 2+ ion. The asymmetric emission spectra show that Eu 2+ has more one emission center in Mg 3 Ca 3 (PO 4 ) 4 , which can be deconvoluted into at least four Gaussian components peaked at 423, 446, 483 and 510 nm. Highlights: ► Mg 3 Ca 3 (PO 4 ) 4 : Eu 2+ phosphor could be effectively excited by UV chips (360–430 nm). ► Mg 3 Ca 3 (PO 4 ) 4 : Eu 2+ phosphor is a potential blue-emitting phosphor for white LEDs. ► Mg 3 Ca 3 (PO 4 ) 4 : Eu 2+ phosphor shows a broadband emission.

  20. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2009-01-01

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

  1. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2008-01-01

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

  2. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2012-01-01

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

  3. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2009-01-01

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

  4. Luminescence dating

    International Nuclear Information System (INIS)

    Rieser, U.

    2013-01-01

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

  5. High luminescent L-cysteine capped CdTe quantum dots prepared at different reaction times

    Science.gov (United States)

    Kiprotich, Sharon; Onani, Martin O.; Dejene, Francis B.

    2018-04-01

    This paper reports a facile synthesis route of high luminescent L-cysteine capped CdTe quantum dots (QDs). The effect of reaction time on the growth mechanism, optical and physical properties of the CdTe QDs was investigated in order to find the suitability of them towards optical and medical applications. The representative high-resolution transmission microscopy (HRTEM) analysis showed that the as-obtained CdTe QDs appeared as spherical particles with excellent monodispersity. The images exhibited clear lattice fringes which are indicative of good crystallinity. The X-ray diffraction (XRD) pattern displayed polycrystalline nature of the QDs which correspond well to zinc blende phase of bulk CdTe. The crystallite sizes calculated from the Scherrer equation were less than 10 nm for different reaction times which were in close agreement with the values estimated from HRTEM. An increase in reaction time improved crystallinity of the sample as explained by highest peak intensity of the XRD supported by the photoluminescence emission spectra which showed high intensity at a longer growth time. It was observed that for prolonged growth time the emission bands were red shifted from about 517-557 nm for 5-180 min of reaction time due to increase in particle sizes. Ultraviolet and visible analysis displayed well-resolved absorption bands which were red shifted upon an increase in reaction time. There was an inverse relation between the band gap and reaction time. Optical band gap decreases from 3.98 to 2.59 eV with the increase in reaction time from 15 to 180 min.

  6. One-Step Preparation of Blue-Emitting (La,Ca)Si3(O,N)5:Ce3+ Phosphors for High-Color Rendering White Light-Emitting Diodes

    Science.gov (United States)

    Yaguchi, Atsuro; Suehiro, Takayuki; Sato, Tsugio; Hirosaki, Naoto

    2011-02-01

    Highly phase-pure (La,Ca)Si3(O,N)5:Ce3+ blue-emitting phosphors were successfully synthesized via the one-step solid-state reaction from the system La2O3-CaO-CeO2-Si3N4. The synthesized (La,Ca)Si3(O,N)5:Ce3+ exhibits tunable blue broadband emission with the dominant wavelength of 466-479 nm and the external quantum efficiency up to ˜45% under 380 nm near-UV (NUV) excitation. Spectral simulations of the trichromatic white light-emitting diodes (LEDs) using (La,Ca)Si3(O,N)5:Ce3+ demonstrated markedly higher color rendering index Ra values of 93-95, compared to 76-90 attained by the systems using a conventional BAM:Eu2+ phosphor or InGaN blue LED. The present achievement indicates the promising applicability of (La,Ca)Si3(O,N)5:Ce3+ as a blue luminescent source for NUV-converting high-color rendering white LEDs.

  7. Novel cookie-with-chocolate carbon dots displaying extremely acidophilic high luminescence

    Science.gov (United States)

    Lu, Siyu; Zhao, Xiaohuan; Zhu, Shoujun; Song, Yubin; Yang, Bai

    2014-10-01

    A fluorescent carbon dot with a cookie-with-chocolate film structure (about 5 × 5 μm2) showed a high fluorescence quantum yield (61.12%) at low pH. It was hydrothermally synthesized from l-serine and l-tryptophan. The formation mechanism of the film with carbon dots (CDs) was investigated. The film structure was formed by hydrogen bonding and π-π stacking interactions between aromatic rings. The strong blue fluorescence of the CDs increased under strong acidic conditions owing to the changes in the N-groups. These cookie-like CDs are attractive for their potential use as effective fluorescent probes for the sensitive detection of aqueous H+ and Fe3+.A fluorescent carbon dot with a cookie-with-chocolate film structure (about 5 × 5 μm2) showed a high fluorescence quantum yield (61.12%) at low pH. It was hydrothermally synthesized from l-serine and l-tryptophan. The formation mechanism of the film with carbon dots (CDs) was investigated. The film structure was formed by hydrogen bonding and π-π stacking interactions between aromatic rings. The strong blue fluorescence of the CDs increased under strong acidic conditions owing to the changes in the N-groups. These cookie-like CDs are attractive for their potential use as effective fluorescent probes for the sensitive detection of aqueous H+ and Fe3+. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr03965c

  8. Highly luminescent hybrid materials based on smectites with polyethylene glycol modified with rhodamine fluorophore

    Czech Academy of Sciences Publication Activity Database

    Sas, S.; Danko, M.; Bizovská, V.; Lang, Kamil; Bujdák, J.

    2017-01-01

    Roč. 138, MAR (2017), s. 25-33 ISSN 0169-1317 Institutional support: RVO:61388980 Keywords : Luminescent polymers * Rhodamine B * Molecular aggregation * Fluorescence * Optical materials Subject RIV: CA - Inorganic Chemistry OBOR OECD: Inorganic and nuclear chemistry Impact factor: 3.101, year: 2016

  9. Synthesis and spectroscopic behavior of highly luminescent Eu 3+-dibenzoylmethanate (DBM) complexes with sulfoxide ligands

    Science.gov (United States)

    Niyama, E.; Brito, H. F.; Cremona, M.; Teotonio, E. E. S.; Reyes, R.; Brito, G. E. S.; Felinto, M. C. F. C.

    2005-09-01

    In this paper the synthesis, characterization and photoluminescent behavior of the [RE(DBM) 3L 2] complexes (RE = Gd and Eu) with a variety of sulfoxide ligands; L = benzyl sulfoxide (DBSO), methyl sulfoxide (DMSO), phenyl sulfoxide (DPSO) and p-tolyl sulfoxide (PTSO) have been investigated in solid state. The emission spectra of the Eu 3+-β-diketonate complexes show characteristics narrow bands arising from the 5D 0 → 7F J ( J = 0-4) transitions, which are split according to the selection rule for C n, C nv or C s site symmetries. The experimental Judd-Ofelt intensity parameters ( Ω2 and Ω4), radiative ( Arad) and non-radiative ( Anrad) decay rates, and R02 for the europium complexes have been determined and compared. The highest value of Ω2 (61.9 × 10 -20 cm 2) was obtained to the complex with PTSO ligand, indicating that Eu 3+ ion is in the highly polarizable chemical environment. The higher values of the experimental quantum yield ( q) and emission quantum efficiency of the emitter 5D 0 level ( η) for the Eu-complexes with DMSO, DBSO and PTSO sulfoxides suggest that these complexes are promising Light Conversion Molecular Devices (LCMDs). The lower value of quantum yield ( q = 1%), for the hydrated complex [Eu(DBM) 3(H 2O)], indicates that the luminescence quenching occurs via multiphonon relaxation by coupling with the OH-oscillators from water molecule coordinated to rare earth ion. The pure red emission of the Eu-complexes has been confirmed by ( x, y) color coordinates.

  10. Highly luminescent, high-indium-content InGaN film with uniform composition and full misfit-strain relaxation

    Science.gov (United States)

    Fischer, A. M.; Wei, Y. O.; Ponce, F. A.; Moseley, M.; Gunning, B.; Doolittle, W. A.

    2013-09-01

    We have studied the properties of thick InxGa1-xN films, with indium content ranging from x ˜ 0.22 to 0.67, grown by metal-modulated epitaxy. While the low indium-content films exhibit high density of stacking faults and dislocations, a significant improvement in the crystalline quality and optical properties has been observed starting at x ˜ 0.6. Surprisingly, the InxGa1-xN film with x ˜ 0.67 exhibits high luminescence intensity, low defect density, and uniform full lattice-mismatch strain relaxation. The efficient strain relaxation is shown to be due to a critical thickness close to the monolayer range. These films were grown at low temperatures (˜400 °C) to facilitate indium incorporation and with precursor modulation to enhance surface morphology and metal adlayer diffusion. These findings should contribute to the development of growth techniques for nitride semiconductors under high lattice misfit conditions.

  11. Luminescent materials and their applications

    CERN Document Server

    Virk, Hardev Singh

    2015-01-01

    It is pertinent to note that Luminescence phenomenon has once again occupied a central stage with the announcement of Nobel Prize in October 2014 to three Japanese scientists. The discovery of Galium Nitride proved to be a revolutionary step forward in creation of Blue LEDs. With the advent of LED lamps we now have more long-lasting and more efficient alternatives to older light sources. The Volume under reference consists of 9 Chapters, written by experts in the area of Luminescent Materials. First 5 Chapters are contributed as Review Papers and the last 4 are based on Research Papers.Chapter

  12. Luminescence of the SrCl2:Pr crystals under high-energy excitation

    International Nuclear Information System (INIS)

    Antonyak, O.T.; Voloshinovskii, A.S.; Vistovskyy, V.V.; Stryganyuk, G.B.; Kregel, O.P.

    2014-01-01

    The present research was carried out in order to elucidate the mechanisms of energy transfer from the crystal lattice to Pr 3+ ions in SrCl 2 . The luminescence excitation and emission spectra as well as luminescence kinetics of the SrCl 2 :Pr single crystals containing 0.2 mol% Pr were investigated at 300 and 10 K using the vacuum ultraviolet (VUV) synchrotron radiation. The X-ray excited luminescence spectra of the SrCl 2 :Pr (C Pr =0.2 and 0.5 mol%) and SrCl 2 :Pr, K (C Pr =1.5 mol%; C K =1.5 mol%) crystals were studied at 294 and 80 K. Under optical excitation of the samples in the Pr 3+ absorption bands, there were observed five fast ultraviolet emissions assigned to the 4f 1 5d→4f 2 transitions, and two long-wave bands corresponding to the f–f transitions. Furthermore, the intrinsic emission bands of SrCl 2 were observed at 10 K. The X-ray excited luminescence spectrum of the SrCl 2 :Pr crystal containing 0.2 mol% Pr, besides intrinsic emission band near 400 nm, has got a long-wave band at about 490 nm of the Pr 3+ centers. There were not observed any emission bands of the Pr 3+ centers corresponding to the 4f 1 5d–4f 2 transitions in the X-ray excited luminescence spectrum of the SrCl 2 :Pr crystal. The possible mechanisms of energy transfer from the SrCl 2 matrix to the Pr 3+ centers are discussed. -- Highlights: • Spectral-luminescent properties of SrCl 2 :Pr have been investigated. • The identification of emission 4f–4f and 5d–4f bands of Pr 3+ ions was performed. • Adding of potassium prevents clustering of the Pr 3+ centers in the SrCl 2 :Pr, K crystals. • Under X-ray excitation at 80–300 K only Pr 3+ 4f–4f and intrinsic emission is observed

  13. Study on luminescence and thermal stability of blue-emitting Sr_5(PO_4)_3F: Eu"2"+phosphor for application in InGaN-based LEDs

    International Nuclear Information System (INIS)

    Liu, Jie; Zhang, Zhi-Ming; Wu, Zhan-Chao; Wang, Fang-Fang; Li, Zhen-Jiang

    2017-01-01

    Highlights: • A blue phosphor Sr_5(PO_4)_3F: Eu"2"+ was prepared at low temperature of 800 °C. • The broad excitation band of the phosphor matches well with NUV LED chips. • The phosphor shows high color purity and good color stability. • A bright blue-emitting LED was fabricated with this phosphor on an InGaN chip. - Abstract: A series of blue-emitting phosphors Sr_5(PO_4)_3F: Eu"2"+ were synthesized by traditional high temperature solid-state reaction method. The micro-morphology and photoluminescence properties of the phosphors were investigated. The Sr_5(PO_4)_3F: Eu"2"+ phosphors exhibit broad excitation spectra ranging from 250 to 420 nm, and an intense asymmetric blue emission band peaking at 435 nm. Two different Eu"2"+ emission centers in Sr_5(PO_4)_3F: Eu"2"+ phosphors were confirmed via their fluorescence properties. The concentration quenching mechanism, fluorescence lifetime and thermal stability of Sr_5(PO_4)_3F: Eu"2"+ phosphors were studied in detail. The thermal stability can be improved obviously by anion substitution. The CIE chromaticity coordinates of Sr_5(PO_4)_3F: Eu"2"+ phosphors with different Eu"2"+-doped concentrations were calculated. A blue light-emitting diode was fabricated by combination of a 370 nm InGaN chip and the prepared phosphor Sr_5(PO_4)_3F: Eu"2"+. The present work suggests that Sr_5(PO_4)_3F: Eu"2"+ is a potential phosphor applied in InGaN-based LEDs.

  14. Study on luminescence and thermal stability of blue-emitting Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}phosphor for application in InGaN-based LEDs

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Jie; Zhang, Zhi-Ming [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wu, Zhan-Chao, E-mail: wuzhan_chao@163.com [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Wang, Fang-Fang [State Key Laboratory Base of Eco-chemical Engineering, Laboratory of Inorganic Synthesis and Applied Chemistry, College of Chemistry and Molecular Engineering, Qingdao University of Science and Technology, Qingdao 266042 (China); Li, Zhen-Jiang, E-mail: zjli126@126.com [State Key Laboratory Base of Eco-chemical Engineering, College of Sino-German Science and Technology, Qingdao University of Science and Technology, 53 Zhengzhou Road, Qingdao 266042, Shandong (China)

    2017-07-15

    Highlights: • A blue phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} was prepared at low temperature of 800 °C. • The broad excitation band of the phosphor matches well with NUV LED chips. • The phosphor shows high color purity and good color stability. • A bright blue-emitting LED was fabricated with this phosphor on an InGaN chip. - Abstract: A series of blue-emitting phosphors Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} were synthesized by traditional high temperature solid-state reaction method. The micro-morphology and photoluminescence properties of the phosphors were investigated. The Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors exhibit broad excitation spectra ranging from 250 to 420 nm, and an intense asymmetric blue emission band peaking at 435 nm. Two different Eu{sup 2+} emission centers in Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were confirmed via their fluorescence properties. The concentration quenching mechanism, fluorescence lifetime and thermal stability of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors were studied in detail. The thermal stability can be improved obviously by anion substitution. The CIE chromaticity coordinates of Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} phosphors with different Eu{sup 2+}-doped concentrations were calculated. A blue light-emitting diode was fabricated by combination of a 370 nm InGaN chip and the prepared phosphor Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+}. The present work suggests that Sr{sub 5}(PO{sub 4}){sub 3}F: Eu{sup 2+} is a potential phosphor applied in InGaN-based LEDs.

  15. A high sensitivity optically stimulated luminescence scanning system for measurement of single sand-sized grains

    DEFF Research Database (Denmark)

    Duller, G.A.T.; Bøtter-Jensen, L.; Kohsiek, P.

    1999-01-01

    An instrument has been designed for the routine analysis of the optically stimulated luminescence signal from single grains of sand. The system is capable of analysing over 3000 individual grains in a single measurement sequence, and the OSL signal from each grain can be read in less than 3 s....... The design principles are described, along with preliminary measurements that illustrate the operation of the system and its capabilities....

  16. A Highly Luminescent Hexanuclear Molybdenum Cluster - A Promising Candidate toward Photoactive Materials

    Czech Academy of Sciences Publication Activity Database

    Kirakci, Kaplan; Kubát, Pavel; Dušek, Michal; Fejfarová, Karla; Šícha, Václav; Mosinger, Jiří; Lang, Kamil

    2012-01-01

    Roč. 2012, č. 19 (2012), s. 3107-3111 ISSN 1434-1948 R&D Projects: GA ČR(CZ) GAP204/11/0809; GA ČR GAP208/10/1678 Institutional support: RVO:61388980 ; RVO:61388955 ; RVO:68378271 Keywords : cluster compounds * luminescence * molybdenum * organic-inorganic hybrid composites * singlet oxygen Subject RIV: CA - Inorganic Chemistry Impact factor: 3.120, year: 2012

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

    Czech Academy of Sciences Publication Activity Database

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

    2012-01-01

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

  18. High resolution luminescence chronology for Xiashu Loess deposits of Southeastern China

    Science.gov (United States)

    Yi, Shuangwen; Li, Xusheng; Han, Zhiyong; Lu, Huayu; Liu, Jinfeng; Wu, Jiang

    2018-04-01

    Loess deposits in Xiashu are representative of such deposits in Southeastern China that are mainly distributed in the middle and lower reaches of the Yangtze River valley. These loess-paleosol sequences provide a key archive of past climate change in humid, subtropical regions. However, the ages of the sequences are not well constrained. In this study, the standard quartz single-aliquot regenerative (SAR) dose optically stimulated luminescence (OSL) and K-feldspar post-infrared infrared stimulated luminescence (post-IR IRSL; pIRIR290) methods are used to date two loess sequences in Nanjing region. Our results show that quartz SAR OSL and K-feldspar pIRIR290 ages are more or less indistinguishable from one another up to ∼50 ka. Beyond this age, the K-feldspar pIRIR ages increased systematically with deposition depth, agreeing well with the expected ages as far as ∼200 ka. On the basis of a fully independently-dated timescale, we are therefore able to propose, for the first time, a new age model for the Xiashu Loess deposits accumulated since the penultimate interglacial period. Using our newly obtained luminescence dating ages, we observe a marked difference between the loess accumulation rates in the two sequences, potentially forced by regional depositional processes and loess preservation.

  19. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    International Nuclear Information System (INIS)

    Miao Yan-Qin; Zhang Ai-Qin; Li Yuan-Hao; Wang Hua; Jia Hu-Sheng; Liu Xu-Guang; Gao Zhi-Xiang; Tsuboi Taijuf

    2015-01-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7, 7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. (paper)

  20. From Big Data to Big Displays High-Performance Visualization at Blue Brain

    KAUST Repository

    Eilemann, Stefan

    2017-10-19

    Blue Brain has pushed high-performance visualization (HPV) to complement its HPC strategy since its inception in 2007. In 2011, this strategy has been accelerated to develop innovative visualization solutions through increased funding and strategic partnerships with other research institutions. We present the key elements of this HPV ecosystem, which integrates C++ visualization applications with novel collaborative display systems. We motivate how our strategy of transforming visualization engines into services enables a variety of use cases, not only for the integration with high-fidelity displays, but also to build service oriented architectures, to link into web applications and to provide remote services to Python applications.

  1. Paleodosimetrical properties of sodium alkali feldspars and problems of luminescence dating of sediments

    International Nuclear Information System (INIS)

    Huett, Galina; Jaek, Ivar

    1996-01-01

    Emission spectra of natural alkali feldspars extracted from sediments are studied using a CCD-camera based high sensitivity spectrometer. Applying a semiconductor laser (860± 1 nm), two dominant emission bands, blue (410 nm) and orange (570 nm), are revealed in infrared optically stimulated luminescence (IROSL) spectra for the most of the sediments from Scandinavian sections. Luminescence and dosimetric al properties of the hole traps, the induced orange emission band typical of sodium alkali feldspars are studied. As a result, high light bleach ability but low stability of the dosimetric al information lit sodium alkali feldspars are established. Problems of luminescence dating of sediments based on the mixture of potassium-sodium alkali feldspars are discussed. (author)

  2. Aqueous synthesis of highly luminescent glutathione-capped Mn{sup 2+}-doped ZnS quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Kolmykov, Oleksii [Université de Lorraine, Laboratoire Réactions et Génie des Procédés (LRGP), UMR 7274, CNRS, 1 rue Grandville, BP 20451, 54001 Nancy Cedex (France); Coulon, Joël [Université de Lorraine, Laboratoire de Chimie Physique et Microbiologie pour l' Environnement (LCPME), UMR 7564, CNRS, Faculté de Pharmacie, 5 rue Albert Lebrun, 54000 Nancy (France); Lalevée, Jacques [Institut de Science des Matériaux de Mulhouse (IS2M), UMR 7361, CNRS, 15 rue Jean Starcky, 68093 Mulhouse (France); Alem, Halima; Medjahdi, Ghouti [Université de Lorraine, Institut Jean Lamour (IJL), UMR 7198, CNRS, BP 70239, 54506 Vandoeuvre-lès-Nancy Cedex (France); Schneider, Raphaël, E-mail: raphael.schneider@univ-lorraine.fr [Université de Lorraine, Laboratoire Réactions et Génie des Procédés (LRGP), UMR 7274, CNRS, 1 rue Grandville, BP 20451, 54001 Nancy Cedex (France)

    2014-11-01

    In this paper, an aqueous-based route has been developed to prepare highly luminescent glutathione (GSH)-capped Mn-doped ZnS quantum dots (QDs). The dots obtained have an average diameter of 4.3 nm and exhibit the Mn{sup 2+}-related orange luminescence with very low surface defect density. The highest photoluminescence was observed for a Mn{sup 2+} to Zn{sup 2+} molar ratio of 3%. Consecutive overcoating of the Mn:ZnS@GSH QDs by a ZnS shell was done, and the core/shell structured QDs exhibit a PL quantum yield of 23%. Transmission electron microscopy, X-ray powder diffraction, electron spin resonance, X-ray photoelectron spectroscopy, UV–visible spectroscopy and spectrofluorometry have been used to characterize the crystal structure, the doping status, and the optical properties of the doped-QDs. Our systematic investigation shows that Mn:ZnS/ZnS@GSH QDs are highly promising fluorescent labels in biological applications.

  3. Toward an ultra-high resolution community climate system model for the BlueGene platform

    International Nuclear Information System (INIS)

    Dennis, John M; Jacob, Robert; Vertenstein, Mariana; Craig, Tony; Loy, Raymond

    2007-01-01

    Global climate models need to simulate several small, regional-scale processes which affect the global circulation in order to accurately simulate the climate. This is particularly important in the ocean where small scale features such as oceanic eddies are currently represented with adhoc parameterizations. There is also a need for higher resolution to provide climate predictions at small, regional scales. New high-performance computing platforms such as the IBM BlueGene can provide the necessary computational power to perform ultra-high resolution climate model integrations. We have begun to investigate the scaling of the individual components of the Community Climate System Model to prepare it for integrations on BlueGene and similar platforms. Our investigations show that it is possible to successfully utilize O(32K) processors. We describe the scalability of five models: the Parallel Ocean Program (POP), the Community Ice CodE (CICE), the Community Land Model (CLM), and the new CCSM sequential coupler (CPL7) which are components of the next generation Community Climate System Model (CCSM); as well as the High-Order Method Modeling Environment (HOMME) which is a dynamical core currently being evaluated within the Community Atmospheric Model. For our studies we concentrate on 1/10 0 resolution for CICE, POP, and CLM models and 1/4 0 resolution for HOMME. The ability to simulate high resolutions on the massively parallel petascale systems that will dominate high-performance computing for the foreseeable future is essential to the advancement of climate science

  4. Sub-100 fs high average power directly blue-diode-laser-pumped Ti:sapphire oscillator

    Science.gov (United States)

    Rohrbacher, Andreas; Markovic, Vesna; Pallmann, Wolfgang; Resan, Bojan

    2016-03-01

    Ti:sapphire oscillators are a proven technology to generate sub-100 fs (even sub-10 fs) pulses in the near infrared and are widely used in many high impact scientific fields. However, the need for a bulky, expensive and complex pump source, typically a frequency-doubled multi-watt neodymium or optically pumped semiconductor laser, represents the main obstacle to more widespread use. The recent development of blue diodes emitting over 1 W has opened up the possibility of directly diode-laser-pumped Ti:sapphire oscillators. Beside the lower cost and footprint, a direct diode pumping provides better reliability, higher efficiency and better pointing stability to name a few. The challenges that it poses are lower absorption of Ti:sapphire at available diode wavelengths and lower brightness compared to typical green pump lasers. For practical applications such as bio-medicine and nano-structuring, output powers in excess of 100 mW and sub-100 fs pulses are required. In this paper, we demonstrate a high average power directly blue-diode-laser-pumped Ti:sapphire oscillator without active cooling. The SESAM modelocking ensures reliable self-starting and robust operation. We will present two configurations emitting 460 mW in 82 fs pulses and 350 mW in 65 fs pulses, both operating at 92 MHz. The maximum obtained pulse energy reaches 5 nJ. A double-sided pumping scheme with two high power blue diode lasers was used for the output power scaling. The cavity design and the experimental results will be discussed in more details.

  5. Selectively Modulating Triplet Exciton Formation in Host Materials for Highly Efficient Blue Electrophosphorescence.

    Science.gov (United States)

    Li, Huanhuan; Bi, Ran; Chen, Ting; Yuan, Kai; Chen, Runfeng; Tao, Ye; Zhang, Hongmei; Zheng, Chao; Huang, Wei

    2016-03-23

    The concept of limiting the triplet exciton formation to fundamentally alleviate triplet-involved quenching effects is introduced to construct host materials for highly efficient and stable blue phosphorescent organic light-emitting diodes (PhOLEDs). The low triplet exciton formation is realized by small triplet exciton formation fraction and rate with high binding energy and high reorganization energy of triplet exciton. Demonstrated in two analogue molecules in conventional donor-acceptor molecule structure for bipolar charge injection and transport with nearly the same frontier orbital energy levels and triplet excited energies, the new concept host material shows significantly suppressed triplet exciton formation in the host to avoid quenching effects, leading to much improved device efficiencies and stabilities. The low-voltage-driving blue PhOLED devices exhibit maximum efficiencies of 43.7 cd A(-1) for current efficiency, 32.7 lm W(-1) for power efficiency, and 20.7% for external quantum efficiency with low roll-off and remarkable relative quenching effect reduction ratio up to 41%. Our fundamental solution for preventing quenching effects of long-lived triplet excitons provides exciting opportunities for fabricating high-performance devices using the advanced host materials with intrinsically small triplet exciton formation cross section.

  6. High-performance blue phosphorescent OLEDs using energy transfer from exciplex.

    Science.gov (United States)

    Seino, Yuki; Sasabe, Hisahiro; Pu, Yong-Jin; Kido, Junji

    2014-03-12

    An efficient energy transfer from an exciplex between a sulfone and an arylamine derivatives to a blue phosphorescent emitter enables OLED performances among the best, of over 50 lm W(-1) at 100 cd m(-2) . The formation of the exciplex realizes a barrier-free hole-electron recombination pathway, thereby leading to high OLED performances with an extremely low driving voltage of 2.9 V at 100 cd m(-2) . © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Temperature dependent luminescence Cr3+doped GdAl3(BO3)4 and YAl3(BO3)4

    NARCIS (Netherlands)

    Malysa, B.; Meijerink, A; Jüstel, Thomas

    Chromium activated YAl3(BO3)4 (YAB) and GdAl3(BO3)4 (GAB) were synthesized and show efficient broad band near infrared emission under excitation in the UV, blue and orange spectral regions. Temperature dependent luminescence measurements for GAB:1%Cr3+ and YAB:1%Cr3+ reveal high quenching

  8. Highly luminescent nanostructures of CdS and ZnS prepared by microwaves heating: effect of sulphide concentration

    Energy Technology Data Exchange (ETDEWEB)

    Ortiz, Samuel; Gomez, Idalia; Elizondo, Perla [Facultad de Ciencias Quimicas, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, C.P. 66450 San Nicolas de los Garza (Mexico); Cavazos, Jose [Facultad de Ingenieria Mecanica y Electrica, Universidad Autonoma de Nuevo Leon, Av. Universidad s/n, C.P. 66450 San Nicolas de los Garza (Mexico)

    2010-11-15

    Nearly monodisperse and highly luminescent ZnS and CdS NPs were obtained by microwave irradiation. The ZnS and CdS NPs solutions were prepared by adding freshly prepared ZnSO{sub 4} or CdSO{sub 4} solution to a thioacetamide solution at pH 8 in the presence of sodium citrate in solution used as stabilizer. The precursors concentration were such that the sulphide ion concentrations were 3 x 10{sup -2} M, 6 x 10{sup -2} M and 8 x 10{sup -2} M, for each of these [S] concentrations the [Zn] or [Cd] content were fixed at 3 x 10{sup -2} M. NPs were prepared under microwave irradiation for 1 min at 905 W of power. The NPs samples were taken when the temperature descended to ambient temperature for further analysis. Effect of concentration of Cd and Zn ions were studied in the luminescence property. RXD, AFM, TEM and UV-Vis were used too as analytical equipment for characterization. (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  9. Luminescence and structural study of porous silicon films

    Science.gov (United States)

    Xie, Y. H.; Wilson, W. L.; Ross, F. M.; Mucha, J. A.; Fitzgerald, E. A.; Macaulay, J. M.; Harris, T. D.

    1992-03-01

    A combination of photoluminescence, TEM, and Fourier transform IR spectroscopy is used to investigate the luminescence properties of 3-micron thick, strongly emitting, and highly porous silicon films. TEMs indicate that these samples have structures of predominantly 6-7-nm size clusters. In the as-prepared films, there is a significant concentration of Si-H bonds which is gradually replaced by Si-O bonds during prolonged aging in air. Upon optical excitation these films exhibit strong visible emission, peaking at about 690 nm. The excitation edge is shown to be emission-wavelength dependent, revealing the inhomogeneous nature of both the initially photoexcited and luminescing species. The correlation of the spectral and structural information suggest that the source of the large blue shift of the visible emission compared to the bulk Si bandgap energy is due to quantum confinement in the nanometer-size Si clusters.

  10. luminescence properties

    Indian Academy of Sciences (India)

    1Faculty of Science and Arts, Department of Chemistry, Bozok University, Yozgat 66900, Turkey. 2Faculty of Science, Department of Chemistry, Erciyes ... synthesized by the conventional solid-state reaction method, their crystal structures and luminescence properties were investigated. X-ray diffraction patterns (XRD) ...

  11. High color rendering index white organic light-emitting diode using levofloxacin as blue emitter

    Science.gov (United States)

    Miao, Yan-Qin; Gao, Zhi-Xiang; Zhang, Ai-Qin; Li, Yuan-Hao; Wang, Hua; Jia, Hu-Sheng; Liu, Xu-Guang; Tsuboi, Taijuf

    2015-05-01

    Levofloxacin (LOFX), which is well-known as an antibiotic medicament, was shown to be useful as a 452-nm blue emitter for white organic light-emitting diodes (OLEDs). In this paper, the fabricated white OLED contains a 452-nm blue emitting layer (thickness of 30 nm) with 1 wt% LOFX doped in CBP (4,4’-bis(carbazol-9-yl)biphenyl) host and a 584-nm orange emitting layer (thickness of 10 nm) with 0.8 wt% DCJTB (4-(dicyanomethylene)-2-tert-butyl-6-(1,1,7,7-tetramethyljulolidin-4-yl-vinyl)-4H-pyran) doped in CBP, which are separated by a 20-nm-thick buffer layer of TPBi (2,2’,2”-(benzene-1,3,5-triyl)-tri(1-phenyl-1H-benzimidazole). A high color rendering index (CRI) of 84.5 and CIE chromaticity coordinates of (0.33, 0.32), which is close to ideal white emission CIE (0.333, 0.333), are obtained at a bias voltage of 14 V. Taking into account that LOFX is less expensive and the synthesis and purification technologies of LOFX are mature, these results indicate that blue fluorescence emitting LOFX is useful for applications to white OLEDs although the maximum current efficiency and luminance are not high. The present paper is expected to become a milestone to using medical drug materials for OLEDs. Project supported by the Program for New Century Excellent Talents in University of Ministry of Education of China (Grant No. NCET-13-0927), the International Science & Technology Cooperation Program of China (Grant No. 2012DFR50460), the National Natural Science Foundation of China (Grant Nos. 21101111 and 61274056), and the Shanxi Provincial Key Innovative Research Team in Science and Technology, China (Grant No. 2012041011).

  12. High-pressure homogenization associated hydrothermal process of palygorskite for enhanced adsorption of Methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Zhifang [Center of Eco-materials and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); University of the Chinese Academy of Sciences, Beijing 100049 (China); Wang, Wenbo [Center of Eco-materials and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); R& D Center of Xuyi Attapulgite Applied Technology, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Xuyi 211700 (China); Wang, Aiqin, E-mail: aqwang@licp.cas.cn [Center of Eco-materials and Green Chemistry, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000 (China); R& D Center of Xuyi Attapulgite Applied Technology, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Xuyi 211700 (China)

    2015-02-28

    Graphical abstract: - Highlights: • Palygorskite was modified by a homogenization associated hydrothermal process. • The crystal bundles of PAL were disaggregated efficiently after modification. • The adsorption of palygorskite for Methylene blue was greatly enhanced. • MB-loaded palygorskite exhibits excellent resistance to acid and alkali solution. - Abstract: Palygorskite (PAL) was modified by a high-pressure homogenization assisted hydrothermal process. The effects of modification on the morphology, structure and physicochemical properties of PAL were systematically investigated by Field-emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR), Brunauer–Emmett–Teller (BET) analysis, X-ray diffraction (XRD) and Zeta potential analysis techniques, and the adsorption properties were systematically evaluated using Methylene blue (MB) as the model dye. The results revealed that the crystal bundles were disaggregated and the PAL nanorods became more even after treated via associated high-pressure homogenization and hydrothermal process, and the crystal bundles were dispersed as nanorods. The intrinsic crystal structure of PAL was remained after hydrothermal treatment, and the pore size calculated by the BET method was increased. The adsorption properties of PAL for MB were evidently improved (from 119 mg/g to 171 mg/g) after modification, and the dispersion of PAL before hydrothermal reaction is favorable to the adsorption. The desorption evaluation confirms that the modified PAL has stronger affinity with MB, which is benefit to fabricate a stable organic–inorganic hybrid pigment.

  13. Searching for Models Exhibiting High Circularly Polarized Luminescence: the Electroactive Inherently Chiral Oligothiophenes.

    Science.gov (United States)

    Benincori, Tiziana; Appoloni, Giulio; Mussini, Patrizia Romana; Arnaboldi, Serena; Cirilli, Roberto; Quartapelle Procopio, Elsa; Panigati, Monica; Abbate, Sergio; Mazzeo, Giuseppe; Longhi, Giovanna

    2018-05-02

    Two new inherently chiral oligothiophenes characterized by the atropisomeric 3,3'-bithianaphtene scaffold functionalized with fused ring bithiophene derivatives, namely 4H-cyclopenta [2,1-b3:4b']dithiophene (CPDT) and dithieno[3,3-b:2',3'-d]pyrrole (DTP), were synthesized. The racemates were fully characterized and resolved into antipodes by enantioselective HPLC. The enantiomers were analyzed through different chiroptical techniques: electronic circular dichroism (ECD) and vibrational circular dichroism (VCD) were employed to attribute the absolute configuration (AC). Comparison of experimental and calculated VCD spectra confirmed the DFT calculated conformational characteristics. The compound functionalized with two CPDT units was oxidized with FeCl3 and ECD and CPL of the resulting material were measured. Circularly Polarized Luminescence (CPL) was measured in order to verify if inherently chiral oligothiophenes could be promising systems for chiral photonics applications. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Layer-by-layer assembly of multicolored semiconductor quantum dots towards efficient blue, green, red and full color optical films

    International Nuclear Information System (INIS)

    Zhang Jun; Li Qian; Di Xiaowei; Liu Zhiliang; Xu Gang

    2008-01-01

    Multicolored semiconductor quantum dots have shown great promise for construction of miniaturized light-emitting diodes with compact size, low weight and cost, and high luminescent efficiency. The unique size-dependent luminescent property of quantum dots offers the feasibility of constructing single-color or full-color output light-emitting diodes with one type of material. In this paper, we have demonstrated the facile fabrication of blue-, green-, red- and full-color-emitting semiconductor quantum dot optical films via a layer-by-layer assembly technique. The optical films were constructed by alternative deposition of different colored quantum dots with a series of oppositely charged species, in particular, the new use of cationic starch on glass substrates. Semiconductor ZnSe quantum dots exhibiting blue emission were deposited for fabrication of blue-emitting optical films, while semiconductor CdTe quantum dots with green and red emission were utilized for construction of green- and red-emitting optical films. The assembly of integrated blue, green and red semiconductor quantum dots resulted in full-color-emitting optical films. The luminescent optical films showed very bright emitting colors under UV irradiation, and displayed dense, smooth and efficient luminous features, showing brighter luminescence in comparison with their corresponding quantum dot aqueous colloid solutions. The assembled optical films provide the prospect of miniaturized light-emitting-diode applications.

  15. High Quantum Yield Blue Emission from Lead-Free Inorganic Antimony Halide Perovskite Colloidal Quantum Dots.

    Science.gov (United States)

    Zhang, Jian; Yang, Ying; Deng, Hui; Farooq, Umar; Yang, Xiaokun; Khan, Jahangeer; Tang, Jiang; Song, Haisheng

    2017-09-26

    Colloidal quantum dots (QDs) of lead halide perovskite have recently received great attention owing to their remarkable performances in optoelectronic applications. However, their wide applications are hindered from toxic lead element, which is not environment- and consumer-friendly. Herein, we utilized heterovalent substitution of divalent lead (Pb 2+ ) with trivalent antimony (Sb 3+ ) to synthesize stable and brightly luminescent Cs 3 Sb 2 Br 9 QDs. The lead-free, full-inorganic QDs were fabricated by a modified ligand-assisted reprecipitation strategy. A photoluminescence quantum yield (PLQY) was determined to be 46% at 410 nm, which was superior to that of other reported halide perovskite QDs. The PL enhancement mechanism was unraveled by surface composition derived quantum-well band structure and their large exciton binding energy. The Br-rich surface and the observed 530 meV exciton binding energy were proposed to guarantee the efficient radiative recombination. In addition, we can also tune the inorganic perovskite QD (Cs 3 Sb 2 X 9 ) emission wavelength from 370 to 560 nm via anion exchange reactions. The developed full-inorganic lead-free Sb-perovskite QDs with high PLQY and stable emission promise great potential for efficient emission candidates.

  16. Highly efficient blue OLEDs based on diphenylaminofluorenylstyrenes end-capped with heterocyclic aromatics

    Energy Technology Data Exchange (ETDEWEB)

    Oh, Suhyun [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Lee, Kum Hee; Kim, Young Kwan [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Yoon, Seung Soo, E-mail: ssyoon@skku.edu [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of)

    2012-10-15

    In this paper, we have designed four diphenylaminofluorenylstyrene derivatives end-capped with heterocyclic aromatic groups, such as 9-phenylcabazole, 4-dibenzofuran, 2-benzoxazole, 2-quinoxaline, respectively. These materials showed blue to red fluorescence with maximum emission wavelengths of 476–611 nm, respectively, which were dependent on the structural and electronic nature of end-capping groups. To explore the electroluminescent properties of these materials, multilayer OLEDs were fabricated in the following sequence: ITO/DNTPD (40 nm)/NPB (20 nm)/2% doped in MADN (20 nm)/Alq{sub 3} (40 nm)/Liq. (1 nm)/Al. Among those, a device exhibited a highly efficient blue emission with the maximum luminance of 14,480 cd/m{sup 2} at 9 V, the luminous efficiency of 5.38 cd/A at 20 mA/cm{sup 2}, power efficiency of 2.77 lm/W at 20 mA/cm{sup 2}, and CIE{sub x,y} coordinates of (0.147, 0.152) at 8 V, respectively.

  17. Toward an ultra-high resolution community climate system model for the BlueGene platform

    Energy Technology Data Exchange (ETDEWEB)

    Dennis, John M [Computer Science Section, National Center for Atmospheric Research, Boulder, CO (United States); Jacob, Robert [Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL (United States); Vertenstein, Mariana [Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, CO (United States); Craig, Tony [Climate and Global Dynamics Division, National Center for Atmospheric Research, Boulder, CO (United States); Loy, Raymond [Mathematics and Computer Science Division, Argonne National Laboratory, Argonne, IL (United States)

    2007-07-15

    Global climate models need to simulate several small, regional-scale processes which affect the global circulation in order to accurately simulate the climate. This is particularly important in the ocean where small scale features such as oceanic eddies are currently represented with adhoc parameterizations. There is also a need for higher resolution to provide climate predictions at small, regional scales. New high-performance computing platforms such as the IBM BlueGene can provide the necessary computational power to perform ultra-high resolution climate model integrations. We have begun to investigate the scaling of the individual components of the Community Climate System Model to prepare it for integrations on BlueGene and similar platforms. Our investigations show that it is possible to successfully utilize O(32K) processors. We describe the scalability of five models: the Parallel Ocean Program (POP), the Community Ice CodE (CICE), the Community Land Model (CLM), and the new CCSM sequential coupler (CPL7) which are components of the next generation Community Climate System Model (CCSM); as well as the High-Order Method Modeling Environment (HOMME) which is a dynamical core currently being evaluated within the Community Atmospheric Model. For our studies we concentrate on 1/10{sup 0} resolution for CICE, POP, and CLM models and 1/4{sup 0} resolution for HOMME. The ability to simulate high resolutions on the massively parallel petascale systems that will dominate high-performance computing for the foreseeable future is essential to the advancement of climate science.

  18. Highly luminescent InP/GaP/ZnS nanocrystals and their application to white light-emitting diodes.

    Science.gov (United States)

    Kim, Sungwoo; Kim, Taehoon; Kang, Meejae; Kwak, Seong Kwon; Yoo, Tae Wook; Park, Lee Soon; Yang, Ilseung; Hwang, Sunjin; Lee, Jung Eun; Kim, Seong Keun; Kim, Sang-Wook

    2012-02-29

    Highly stable and luminescent InP/GaP/ZnS QDs with a maximum quantum yield of 85% were synthesized by in situ method. The GaP shell rendered passivation of the surface and removed the traps. TCSPC data showed an evidence for the GaP shell. InP/GaP/ZnS QDs show better stability than InP/ZnS. We studied the optical properties of white QD-LEDs corresponding to various QD concentrations. Among various concentrations, the white QD-LEDs with 0.5 mL of QDs exhibited a luminous efficiency of 54.71 lm/W, Ra of 80.56, and CCT of 7864 K. © 2012 American Chemical Society

  19. Probing luminescence centers in Na rich feldspar

    DEFF Research Database (Denmark)

    Prasad, Amit Kumar; Lapp, Torben; Kook, Myung Ho

    2016-01-01

    our understanding of the luminescence mechanisms and recombination sites, in a sample of Na rich plagioclase feldspar (oligoclase). Both the UV and violet–blue emissions show resonant excitations arising from a distribution of energy levels. We propose, contrary to the general understanding...

  20. Nanostructured Ag-zeolite Composites as Luminescence-based Humidity Sensors

    Science.gov (United States)

    Dieu, Bjorn; Roeffaers, Maarten B.J.; Hofkens, Johan

    2016-01-01

    Small silver clusters confined inside zeolite matrices have recently emerged as a novel type of highly luminescent materials. Their emission has high external quantum efficiencies (EQE) and spans the whole visible spectrum. It has been recently reported that the UV excited luminescence of partially Li-exchanged sodium Linde type A zeolites [LTA(Na)] containing luminescent silver clusters can be controlled by adjusting the water content of the zeolite. These samples showed a dynamic change in their emission color from blue to green and yellow upon an increase of the hydration level of the zeolite, showing the great potential that these materials can have as luminescence-based humidity sensors at the macro and micro scale. Here, we describe the detailed procedure to fabricate a humidity sensor prototype using silver-exchanged zeolite composites. The sensor is produced by suspending the luminescent Ag-zeolites in an aqueous solution of polyethylenimine (PEI) to subsequently deposit a film of the material onto a quartz plate. The coated plate is subjected to several hydration/dehydration cycles to show the functionality of the sensing film. PMID:27911397

  1. Towards Luminescence Dating Of Mosaic Glass

    Science.gov (United States)

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

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

  2. Graphene-SnO2 composites for highly efficient photocatalytic degradation of methylene blue under sunlight.

    Science.gov (United States)

    Seema, Humaira; Christian Kemp, K; Chandra, Vimlesh; Kim, Kwang S

    2012-09-07

    Graphene sheets decorated with SnO(2) nanoparticles (RGO-SnO(2)) were prepared via a redox reaction between graphene oxide (GO) and SnCl(2). Graphene oxide (GO) was reduced to graphene (RGO) and Sn(2+) was oxidized to SnO(2) during the redox reaction, leading to a homogeneous distribution of SnO(2) nanoparticles on RGO sheets. The scanning electron microscopy (SEM) and transmission electron microscopy (TEM) images show uniform distribution of the nanoparticles on the RGO surface and high-resolution transmission electron microscopy (HRTEM) shows an average particle size of 3-5 nm. The RGO-SnO(2) composite showed an enhanced photocatalytic degradation activity for the organic dye methylene blue under sunlight compared to bare SnO(2) nanoparticles. This result leads us to believe that the RGO-SnO(2) composite could be used in catalytic photodegradation of other organic dyes.

  3. Monolithic blue LED series arrays for high-voltage AC operation

    Energy Technology Data Exchange (ETDEWEB)

    Ao, Jin-Ping [Satellite Venture Business Laboratory, University of Tokushima, Tokushima 770-8506 (Japan); Sato, Hisao; Mizobuchi, Takashi; Morioka, Kenji; Kawano, Shunsuke; Muramoto, Yoshihiko; Sato, Daisuke; Sakai, Shiro [Nitride Semiconductor Co. Ltd., Naruto, Tokushima 771-0360 (Japan); Lee, Young-Bae; Ohno, Yasuo [Department of Electrical and Electronic Engineering, University of Tokushima, Tokushima 770-8506 (Japan)

    2002-12-16

    Design and fabrication of monolithic blue LED series arrays that can be operated under high ac voltage are described. Several LEDs, such as 3, 7, and 20, are connected in series and in parallel to meet ac operation. The chip size of a single device is 150 {mu}m x 120 {mu}m and the total size is 1.1 mm x 1 mm for a 40(20+20) LED array. Deep dry etching was performed as device isolation. Two-layer interconnection and air bridge are utilized to connect the devices in an array. The monolithic series array exhibit the expected operation function under dc and ac bias. The output power and forward voltage are almost proportional to LED numbers connected in series. On-wafer measurement shows that the output power is 40 mW for 40(20+20) LED array under ac 72 V. (Abstract Copyright [2002], Wiley Periodicals, Inc.)

  4. Mineralizer-assisted high-pressure high-temperature synthesis and characterization of novel phosphorus nitride imides and luminescent alkaline earth metal (oxo)nitridophosphates

    International Nuclear Information System (INIS)

    Marchuk, Alexey

    2016-01-01

    The main objectives of this thesis were the synthesis, identification and structural characterization of new alkaline earth metal (oxo)nitridophopshates and phosphorus nitrides. Furthermore, luminescence properties of the resulting materials should be investigated and a connection between these properties and the respective structures should be established. For this purpose, a range of synthesis strategies was employed, including conventional solid-state syntheses in silica ampoules and high-pressure high-temperature syntheses using the multianvil technique. The emphasis of the synthetic part of this thesis lies on the development of new synthetic strategies in order to increase crystallinity of alkaline earth metal (oxo)nitridophosphates and thus accelerate their structure determination. This involves the selection of a suitable mineralizer and the investigation of its interaction with the respective starting materials. In addition, the analytical methods applied in this thesis in order to identify and characterize the compounds are just as essential as the synthesis strategies. X-ray diffraction on single crystals and on powders was carried out as the main analytical method while being supported by quantitative and qualitative 1 H and 31 P solid-state NMR measurements, FTIR and energy-dispersive X-ray (EDX) spectroscopy, as well as electron microscopy methods including both imaging and diffraction techniques. Implied by the large number of novel structures investigated, theoretical studies including topological analysis, calculations of lattice energies and bond-valence sums also played a major role in this thesis. Optical analysis methods such as reflectance spectroscopy, luminescence microscopy and photoluminescence measurements helped to determine the luminescence properties of some of the presented compounds.

  5. High-level methodology for carrying out combined red and blue teams

    CSIR Research Space (South Africa)

    Veerasamy, N

    2009-12-01

    Full Text Available This paper proposes a combined Red and Blue Team Methodology to guide the process of carrying out such security auditing and penetration testing tasks. Red and Blue Teams consist of various security auditing and penetration testing tasks which serve...

  6. Cyclometalated Iridium(III) Carbene Phosphors for Highly Efficient Blue Organic Light-Emitting Diodes.

    Science.gov (United States)

    Chen, Zhao; Wang, Liqi; Su, Sikai; Zheng, Xingyu; Zhu, Nianyong; Ho, Cheuk-Lam; Chen, Shuming; Wong, Wai-Yeung

    2017-11-22

    Five deep blue carbene-based iridium(III) phosphors were synthesized and characterized. Interestingly, one of them can be fabricated into deep blue, sky blue and white organic light-emitting diodes (OLEDs) through changing the host materials and exciton blocking layers. These deep and sky blue devices exhibit Commission Internationale de l'Éclairage (CIE) coordinates of (0.145, 0.186) and (0.152, 0.277) with external quantum efficiency (EQE) of 15.2% and 9.6%, respectively. The EQE of the deep blue device can be further improved up to 19.0% by choosing a host with suitable energy level of its lowest unoccupied molecular orbital (LUMO).

  7. Luminescent screens

    International Nuclear Information System (INIS)

    Lu, C.-I.

    1982-01-01

    Luminescent screens which are useful for such purposes as intensifying screens for radiographs are comprised of a support bearing a layer of finely divided particles of a phosphor dispersed in a cross-linked polymeric matrix formed by heat-curing of a coating composition comprising an unsaturated cross-linkable polymer, a polymerizable acrylic monomer, a thermoplastic polyurethane elastomer, and a heat-activatable polymerization initiator. The phosphor layer includes voids formed by evaporation of an evaporable component which is present in the coating composition from which such layer is formed. (author)

  8. Crystal structure and luminescence properties of (Ca{sub 2.94-x}Lu{sub x}Ce{sub 0.06})(Sc{sub 2-y}Mg{sub y})Si{sub 3}O{sub 12} phosphors for white LEDs with excellent colour rendering and high luminous efficiency

    Energy Technology Data Exchange (ETDEWEB)

    Liu Yongfu; Zhang Xia; Hao Zhendong; Lu Wei; Liu Xingyuan; Zhang Jiahua [Key Laboratory of Excited State Processes, Changchun Institute of Optics, Fine Mechanics and Physics, Chinese Academy of Sciences, 3888 Eastern South Lake Road, Changchun 130033 (China); Wang Xiaojun, E-mail: zhangjh@ciomp.ac.cn [Department of Physics, Georgia Southern University, Statesboro, GA 30460 (United States)

    2011-02-23

    Lu-modified (Ca{sub 2.94-x}Lu{sub x}Ce{sub 0.06})(Sc{sub 2-y}Mg{sub y})Si{sub 3}O{sub 12} (CLSMS : Ce{sup 3+}) yellow emitting phosphors are prepared by a solid-state reaction. Controllable luminescent intensity and emitting colour are studied as a function of Lu and Mg contents. Fixing the Mg content to be 1, the effect of Lu content on crystal phase formation, luminescence properties and temperature characteristics is studied. It is revealed that the Lu-induced luminescent enhancement is the result of an increase in absorbance of Ce{sup 3+} rather than the internal quantum efficiency. Intense and broadband emission is realized by controlling the Lu content to obtain a pure CLSMS crystal phase. The maximum luminescence intensity is obtained at x = 0.54, which is as high as 156% of the Lu-free phosphor. The Lu-containing phosphor also exhibits better temperature characteristics for its big activation energy (0.20 eV) than the Lu-free one (0.18 eV). Combining the present phosphor with a blue light-emitting diode (LED) chip, a white LED with an excellent colour rendering index R{sub a} of 86 and a high luminous efficiency of 86 lm W{sup -1} is obtained. The results of the present study demonstrate that the CLSMS : Ce{sup 3+} phosphors show a good performance and are attractive candidates for commercial applications when used in white LEDs.

  9. Tunable white light of a Ce3+,Tb3+,Mn2+ triply doped Na2Ca3Si2O8 phosphor for high colour-rendering white LED applications: tunable luminescence and energy transfer.

    Science.gov (United States)

    Lü, Wei; Xu, Huawei; Huo, Jiansheng; Shao, Baiqi; Feng, Yang; Zhao, Shuang; You, Hongpeng

    2017-07-18

    A tunable white light emitting Na 2 Ca 3 Si 2 O 8 :Ce 3+ ,Tb 3+ ,Mn 2+ phosphor with a high color rendering index (CRI) has been prepared. Under UV excitation, Na 2 Ca 3 Si 2 O 8 :Ce 3+ phosphors present blue luminescence and exhibit a broad excitation ranging from 250 to 400 nm. When codoping Tb 3+ /Mn 2+ ions into Na 2 Ca 3 Si 2 O 8 , energy transfer from Ce 3+ to Tb 3+ and Ce 3+ to Mn 2+ ions is observed from the spectral overlap between Ce 3+ emission and Tb 3+ /Mn 2+ excitation spectra. The energy-transfer efficiencies and corresponding mechanisms are discussed in detail. The mechanism of energy transfer from Ce 3+ to Tb 3+ is demonstrated to be a dipole-quadrupole mechanism by the Inokuti-Hirayama model. The wavelength-tunable white light can be realized by coupling the emission bands centered at 440, 550 and 590 nm ascribed to the contribution from Ce 3+ , Tb 3+ and Mn 2+ , respectively. The commission on illumination value of color tunable emission can be tuned by controlling the content of Ce 3+ , Tb 3+ and Mn 2+ . Temperature-dependent luminescence spectra proved the good thermal stability of the as-prepared phosphor. White LEDs with CRI = 93.5 are finally fabricated using a 365 nm UV chip and the as-prepared Na 2 Ca 3 Si 2 O 8 :Ce 3+ ,Tb 3+ ,Mn 2+ phosphor. All the results suggest that Na 2 Ca 3 Si 2 O 8 :Ce 3+ ,Tb 3+ ,Mn 2+ can act as potential color-tunable and single-phase white emission phosphors for possible applications in UV based white LEDs.

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

    Czech Academy of Sciences Publication Activity Database

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

    2013-01-01

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

  11. Gap state related blue light emitting boron-carbon core shell structures

    International Nuclear Information System (INIS)

    Singh, Paviter; Kaur, Manpreet; Singh, Bikramjeet; Kaur, Gurpreet; Singh, Kulwinder; Kumar, Akshay; Kumar, Manjeet; Bala, Rajni; Thakur, Anup

    2016-01-01

    Boron-carbon core shell structures have been synthesized by solvo-thermal synthesis route. The synthesized material is highly pure. X-ray diffraction analysis confirms the reduction of reactants in to boron and carbon. Scanning Electron Microscopy (SEM) analysis showed that the shell is uniform with average thickness of 340 nm. Photo luminescence studies showed that the material is blue light emitting with CIE color coordinates: x=0.16085, y=0.07554.

  12. High luminescent fibers with hybrid SiO2-coated CdTe nanocrystals fabricated by electrospinning technique

    International Nuclear Information System (INIS)

    Cao, Yongqiang; Liu, Ning; Yang, Ping; Shi, Ruixia; Ma, Qian; Zhang, Aiyu; Zhu, Yuanna; Wang, Junpeng; Wang, Jianrong

    2015-01-01

    The polyvinylpyrrolidone (PVP) hybrid luminescent micro-/nanofibers doped with the novel hybrid SiO 2 -coated CdTe nanocrystals (HS-CdTe NCs) have been fabricated for the first time via the electrospinning technique. The morphologies and photoluminescence (PL) emissions of HS-CdTe/PVP micro-/nanofibers prepared by doping the HS-CdTe NCs with the different PL peak wavelength (571, 616, and 643 nm) in PVP fibers were investigated by optical and PL microscope. The results revealed that all the HS-CdTe/PVP hybrid fibers showed an ultralong length for several hundreds of micrometers and a relatively uniform diameter of 1000 ∼ 1200 nm. The hybrid fibers displayed a wavelength-tunable PL emission, determining by the PL of doped HS-CdTe NCs. Moreover, similar to the original PL properties of HS-CdTe NCs before the electrospinning, the HS-CdTe/PVP fibers also showed a series of superior PL properties, such as narrow and symmetry PL spectrum, high, and uniform brightness. For comparison purpose, we also prepared three CdTe/PVP hybrid fibers by doping the 553 nm, 600 nm, and 633 nm PL-emitting CdTe NCs respectively in PVP electrospinning fibers. The characterization results showed that, the obtained three CdTe/PVP hybrid fibers had a basically satisfactory micro-/nanofiber morphology with a long length and relatively uniform diameter, but all the fibers exhibited very weak PL emissions. The enormous contrast in PL properties between HS-CdTe/PVP and CdTe/PVP fibers should mainly be ascribed to the different connection modes of ligands with the NCs and the passivation effect of inert hybrid silica shell on HS-CdTe. It is hopeful that the high luminescent HS-CdTe/PVP micro-/nanofibers with the tunable PL peak wavelength would be a good candidate in the optical sensor, light-emitting devices (LEDs), nanometer-scale waveguides, and the other related photonic materials. - Highlights: • The HS-CdTe/PVP electrospun hybrid fibers were fabricated for the first time. • The

  13. Material for a luminescent solar concentrator

    Science.gov (United States)

    Andrews, L.J.

    1984-01-01

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

  14. Luminescent Properties of Sr4Si3O8Cl4:Eu2+, Bi3+ Phosphors for Near UV InGaN-Based Light-Emitting-Diodes

    Directory of Open Access Journals (Sweden)

    Wangqing Shen

    2015-12-01

    Full Text Available Sr4Si3O8Cl4 co-doped with Eu2+, Bi3+ were prepared by the high temperature reaction. The structure and luminescent properties of Sr4Si3O8Cl4:Eu2+, Bi3+ were investigated. With the introduction of Bi3+, luminescent properties of these phosphors have been optimized. Compared with Sr3.90Si3O8Cl4:0.10Eu2+, the blue-green phosphor Sr3.50Si3O8Cl4:0.10Eu2+, 0.40Bi3+ shows stronger blue-green emission with broader excitation in near-UV range. Bright blue-green light from the LED means this phosphor can be observed by the naked eye. Hence, it may have an application in near UV LED chips.

  15. Highly Luminescent Phase-Stable CsPbI3 Perovskite Quantum Dots Achieving Near 100% Absolute Photoluminescence Quantum Yield.

    Science.gov (United States)

    Liu, Feng; Zhang, Yaohong; Ding, Chao; Kobayashi, Syuusuke; Izuishi, Takuya; Nakazawa, Naoki; Toyoda, Taro; Ohta, Tsuyoshi; Hayase, Shuzi; Minemoto, Takashi; Yoshino, Kenji; Dai, Songyuan; Shen, Qing

    2017-10-24

    Perovskite quantum dots (QDs) as a new type of colloidal nanocrystals have gained significant attention for both fundamental research and commercial applications owing to their appealing optoelectronic properties and excellent chemical processability. For their wide range of potential applications, synthesizing colloidal QDs with high crystal quality is of crucial importance. However, like most common QD systems such as CdSe and PbS, those reported perovskite QDs still suffer from a certain density of trapping defects, giving rise to detrimental nonradiative recombination centers and thus quenching luminescence. In this paper, we show that a high room-temperature photoluminescence quantum yield of up to 100% can be obtained in CsPbI 3 perovskite QDs, signifying the achievement of almost complete elimination of the trapping defects. This is realized with our improved synthetic protocol that involves introducing organolead compound trioctylphosphine-PbI 2 (TOP-PbI 2 ) as the reactive precursor, which also leads to a significantly improved stability for the resulting CsPbI 3 QD solutions. Ultrafast kinetic analysis with time-resolved transient absorption spectroscopy evidence the negligible electron or hole-trapping pathways in our QDs, which explains such a high quantum efficiency. We expect the successful synthesis of the "ideal" perovskite QDs will exert profound influence on their applications to both QD-based light-harvesting and -emitting devices.

  16. Deep-blue efficient OLED based on NPB with little efficiency roll-off under high current density

    Science.gov (United States)

    Liu, Jian

    2017-03-01

    NPB usually is used as a hole-transport layer in OLED. In fact, it is a standard pure blue-emission material. However, its light-emitting efficiency in OLED is low due to emissive nature of organic material. Herein, a deep-blue OLDE based on NPB was fabricated. The light-emitting efficiency of the device demonstrates a moderate value, and efficiency roll-off is little under high current density. The device demonstrates that the electroplex's emission decreases with increasing electric field intensity.

  17. Uranyl fluoride luminescence in acidic aqueous solutions

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  18. A global and high-resolution assessment of the green, blue and grey water footprint of wheat

    NARCIS (Netherlands)

    Mekonnen, Mesfin; Hoekstra, Arjen Ysbert

    2010-01-01

    The aim of this study is to estimate the green, blue and grey water footprint of wheat in a spatially-explicit way, both from a production and consumption perspective. The assessment is global and improves upon earlier research by taking a high-resolution approach, estimating the water footprint of

  19. High-Brightness Blue Light-Emitting Diodes Enabled by a Directly Grown Graphene Buffer Layer.

    Science.gov (United States)

    Chen, Zhaolong; Zhang, Xiang; Dou, Zhipeng; Wei, Tongbo; Liu, Zhiqiang; Qi, Yue; Ci, Haina; Wang, Yunyu; Li, Yang; Chang, Hongliang; Yan, Jianchang; Yang, Shenyuan; Zhang, Yanfeng; Wang, Junxi; Gao, Peng; Li, Jinmin; Liu, Zhongfan

    2018-06-08

    Single-crystalline GaN-based light-emitting diodes (LEDs) with high efficiency and long lifetime are the most promising solid-state lighting source compared with conventional incandescent and fluorescent lamps. However, the lattice and thermal mismatch between GaN and sapphire substrate always induces high stress and high density of dislocations and thus degrades the performance of LEDs. Here, the growth of high-quality GaN with low stress and a low density of dislocations on graphene (Gr) buffered sapphire substrate is reported for high-brightness blue LEDs. Gr films are directly grown on sapphire substrate to avoid the tedious transfer process and GaN is grown by metal-organic chemical vapor deposition (MOCVD). The introduced Gr buffer layer greatly releases biaxial stress and reduces the density of dislocations in GaN film and In x Ga 1- x N/GaN multiple quantum well structures. The as-fabricated LED devices therefore deliver much higher light output power compared to that on a bare sapphire substrate, which even outperforms the mature process derived counterpart. The GaN growth on Gr buffered sapphire only requires one-step growth, which largely shortens the MOCVD growth time. This facile strategy may pave a new way for applications of Gr films and bring several disruptive technologies for epitaxial growth of GaN film and its applications in high-brightness LEDs. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  20. Highly stable colloidal TiO2 nanocrystals with strong violet-blue emission

    International Nuclear Information System (INIS)

    Ghamsari, Morteza Sasani; Gaeeni, Mohammad Reza; Han, Wooje; Park, Hyung-Ho

    2016-01-01

    Improved sol–gel method has been applied to prepare highly stable colloidal TiO 2 nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO 2 colloidal nanocrystals. HRTEM showed that the diameter of TiO 2 colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO 2 colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO 2 sample has enough potential for optoelectronics applications.

  1. Highly stable colloidal TiO{sub 2} nanocrystals with strong violet-blue emission

    Energy Technology Data Exchange (ETDEWEB)

    Ghamsari, Morteza Sasani, E-mail: msghamsari@yahoo.com [Laser & Optics Research School, NSTRI, 11155-3486 Tehran (Iran, Islamic Republic of); Gaeeni, Mohammad Reza [Laser & Optics Research School, NSTRI, 11155-3486 Tehran (Iran, Islamic Republic of); Han, Wooje; Park, Hyung-Ho [Department of Materials Science and Engineering, Yonsei University, 50 Yonsei-ro, Seodaemun-gu, Seoul 120-749 (Korea, Republic of)

    2016-10-15

    Improved sol–gel method has been applied to prepare highly stable colloidal TiO{sub 2} nanocrystals. The synthesized titania nanocrystals exhibit strong emission in the violet-blue wavelength region. Very long evolution time was obtained by preventing the sol to gel conversion with reflux process. FTIR, XRD, UV–vis absorption, photoluminescence and high resolution transmission electron microscope (HRTEM) were used to study the optical properties, crystalline phase, morphology, shape and size of prepared TiO{sub 2} colloidal nanocrystals. HRTEM showed that the diameter of TiO{sub 2} colloidal nanocrystals is about 5 nm. Although the PL spectra show similar spectral features upon excitation wavelengths at 280, 300 and 350 nm, but their emission intensities are significantly different from each other. Photoluminescence quantum yield for TiO{sub 2} colloidal nanocrystals is estimated to be 49% with 280 nm excitation wavelength which is in agreement and better than reported before. Obtained results confirm that the prepared colloidal TiO{sub 2} sample has enough potential for optoelectronics applications.

  2. High-pressure homogenization associated hydrothermal process of palygorskite for enhanced adsorption of Methylene blue

    Science.gov (United States)

    Zhang, Zhifang; Wang, Wenbo; Wang, Aiqin

    2015-02-01

    Palygorskite (PAL) was modified by a high-pressure homogenization assisted hydrothermal process. The effects of modification on the morphology, structure and physicochemical properties of PAL were systematically investigated by Field-emission scanning electron microscopy (FESEM), Transmission electron microscopy (TEM), Fourier transform infrared spectrometry (FTIR), Brunauer-Emmett-Teller (BET) analysis, X-ray diffraction (XRD) and Zeta potential analysis techniques, and the adsorption properties were systematically evaluated using Methylene blue (MB) as the model dye. The results revealed that the crystal bundles were disaggregated and the PAL nanorods became more even after treated via associated high-pressure homogenization and hydrothermal process, and the crystal bundles were dispersed as nanorods. The intrinsic crystal structure of PAL was remained after hydrothermal treatment, and the pore size calculated by the BET method was increased. The adsorption properties of PAL for MB were evidently improved (from 119 mg/g to 171 mg/g) after modification, and the dispersion of PAL before hydrothermal reaction is favorable to the adsorption. The desorption evaluation confirms that the modified PAL has stronger affinity with MB, which is benefit to fabricate a stable organic-inorganic hybrid pigment.

  3. Preparation of high-purity Pr(3+) doped Ge–Ga–Sb–Se glasses with intensive middle infrared luminescence

    Energy Technology Data Exchange (ETDEWEB)

    Karaksina, E.V.; Shiryaev, V.S., E-mail: shiryaev@ihps.nnov.ru; Kotereva, T.V.; Churbanov, M.F.

    2016-02-15

    Glass materials with high emission characteristics and low content of limiting impurities are required for creation of devices for middle infrared (mid-IR) fiber optics. The paper presents the results of preparation of high-purity Pr{sup 3+}-doped Ga{sub x}Ge{sub y}Sb{sub z}Se{sub 1−(x+y+z)} (x=3÷4, y=20÷26, z=5÷11) glasses. The multi-stage technique for synthesis of these glasses is developed. It is based on chemical distillation purification of glass components and the transport reaction for purification of gallium. Transmitting, as well as thermal and luminescent properties of glasses are investigated. The content of limiting impurities of oxygen, carbon and hydrogen in the glass samples was ≤0.2 ppm wt. The 1300–3000 ppm wt Pr{sup 3+}-doped Ga–Ge–Sb–Se bulk glasses exhibit an intensive photoluminescence in the spectral range of 3.5–5.5 μm.

  4. Synthesis and Features of Luminescent Bromo- and Iodohectorite Nanoclay Materials

    Directory of Open Access Journals (Sweden)

    Hellen Silva Santos

    2017-11-01

    Full Text Available The smectites represent a versatile class of clay minerals with broad usage in industrial applications, e.g., cosmetics, drug delivery, bioimaging, etc. Synthetic hectorite Na0.7(Mg5.5Li0.3[Si8O20](OH4 is a distinct material from this class due to its low-cost production method that allows to design its structure to match better the applications. In the current work, we have synthesized for the first time ever nanoclay materials based on the hectorite structure but with the hydroxyl groups (OH− replaced by Br− or I−, yielding bromohectorite (Br-Hec and iodohectorite (I-Hec. It was aimed that these materials would be used as phosphors. Thus, OH− replacement was done to avoid luminescence quenching by multiphonon de-excitation. The crystal structure is similar to nanocrystalline fluorohectorite, having the d001 spacing of 14.30 Å and 3 nm crystallite size along the 00l direction. The synthetic materials studied here show strong potential to act as host lattices for optically active species, possessing mesoporous structure with high specific surface area (385 and 363 m2 g−1 for Br-Hec and I-Hec, respectively and good thermal stability up to 800 °C. Both materials also present strong blue-green emission under UV radiation and short persistent luminescence (ca. 5 s. The luminescence features are attributed to Ti3+/TiIV impurities acting as the emitting center in these materials.

  5. Highly luminescent and ultrastable CsPbBr{sub 3} perovskite quantum dots incorporated into a silica/alumina monolith

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhichun; Kong, Long; Huang, Shouqiang; Li, Liang [School of Environmental Science and Engineering, Shanghai Jiao Tong University (China)

    2017-07-03

    We successfully prepared QDs incorporated into a silica/alumina monolith (QDs-SAM) by a simple sol-gel reaction of an Al-Si single precursor with CsPbBr{sub 3} QDs blended in toluene solution, without adding water and catalyst. The resultant transparent monolith exhibits high photoluminescence quantum yields (PLQY) up to 90 %, and good photostability under strong illumination of blue light for 300 h. We show that the preliminary ligand exchange of didodecyl dimethyl ammonium bromide (DDAB) was very important to protect CsPbBr{sub 3} QDs from surface damages during the sol-gel reaction, which not only allowed us to maintain the original optical properties of CsPbBr{sub 3} QDs but also prevented the aggregation of QDs and made the monolith transparent. The CsPbBr{sub 3} QDs-SAM in powder form was easily mixed into the resins and applied as color-converting layer with curing on blue light-emitting diodes (LED). The material showed a high luminous efficacy of 80 lm W{sup -1} and a narrow emission with a full width at half maximum (FWHM) of 25 nm. (copyright 2017 Wiley-VCH Verlag GmbH and Co. KGaA, Weinheim)

  6. Highly Luminescent and Ultrastable CsPbBr3 Perovskite Quantum Dots Incorporated into a Silica/Alumina Monolith.

    Science.gov (United States)

    Li, Zhichun; Kong, Long; Huang, Shouqiang; Li, Liang

    2017-07-03

    We successfully prepared QDs incorporated into a silica/alumina monolith (QDs-SAM) by a simple sol-gel reaction of an Al-Si single precursor with CsPbBr 3 QDs blended in toluene solution, without adding water and catalyst. The resultant transparent monolith exhibits high photoluminescence quantum yields (PLQY) up to 90 %, and good photostability under strong illumination of blue light for 300 h. We show that the preliminary ligand exchange of didodecyl dimethyl ammonium bromide (DDAB) was very important to protect CsPbBr 3 QDs from surface damages during the sol-gel reaction, which not only allowed us to maintain the original optical properties of CsPbBr 3 QDs but also prevented the aggregation of QDs and made the monolith transparent. The CsPbBr 3 QDs-SAM in powder form was easily mixed into the resins and applied as color-converting layer with curing on blue light-emitting diodes (LED). The material showed a high luminous efficacy of 80 lm W -1 and a narrow emission with a full width at half maximum (FWHM) of 25 nm. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Understanding and arresting degradation in highly efficient blue emitting BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} phosphor—A longstanding technological problem

    Energy Technology Data Exchange (ETDEWEB)

    Shanker, Ravi; Khan, A.F.; Kumar, Raj; Chander, H.; Shanker, V.; Chawla, Santa, E-mail: santa@mail.nplindia.ernet.in

    2013-11-15

    Blue emitting BaMgAl{sub 10}O{sub 17}:Eu{sup 2+} (BAM) phosphor is indispensable for Plasma Display panel and lighting because of high luminescence efficiency. However, thermal degradation (annealing in air at 500–600 °C) of BAM (upto ∼30%) remains an intriguing problem for display industry worldwide. In the present study, a systematic approach is pursued to develop highly efficient BAM phosphor that exhibits least degradation, understand the role of Eu{sup 2+} site occupancy in such BAM phosphor and encapsulate individual phosphor grains with a shell of silica nanoparticles. The approaches lead to highly efficient BAM:Eu{sup 2+} phosphor that showed no degradation against thermal baking (annealing at 500 °C in air) for both UV and VUV radiation under UV and VUV excitation. An optimum solid state chemical route including precursor phases, dopant concentration, and thermal regimes has been evolved to develop BAM. Emission from Eu{sup 2+} occupying three different sites is identified with energetically stable anti Beevers Ross as the dominant contributor. Coating by nano sized amorphous silica sol with subsequent sintering lead to uniform silica shell. This nano silica layer also helps to enhance the luminescence from phosphor grains. -- Highlights: • Synthesis process optimization done to obtain BAM:Eu{sup 2+} phosphor of high QE (95%). • Site occupancy of Eu{sup 2+} ions in BAM lattice and its relation to stability analyzed. • Individual phosphor grains coated by layer of silica nanoparticles. • Preferred Eu{sup 2+} site occupancy and inert silica layer arrested thermal degradation in BAM. • Developed BAM:Eu{sup 2+} phosphor with high QE is completely thermal degradation resistant.

  8. Highly efficient phosphorescent blue and white organic light-emitting devices with simplified architectures

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Chih-Hao, E-mail: chc@saturn.yzu.edu.tw [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Ding, Yong-Shung; Hsieh, Po-Wei; Chang, Chien-Ping; Lin, Wei-Chieh [Department of Photonics Engineering, Yuan Ze University, Chung-Li, Taiwan 32003 (China); Chang, Hsin-Hua, E-mail: hhua3@mail.vnu.edu.tw [Department of Electro-Optical Engineering, Vanung University, Chung-Li, Taiwan 32061 (China)

    2011-09-01

    Blue phosphorescent organic light-emitting devices (PhOLEDs) with quantum efficiency close to the theoretical maximum were achieved by utilizing a double-layer architecture. Two wide-triplet-gap materials, 1,3-bis(9-carbazolyl)benzene and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, were employed in the emitting and electron-transport layers respectively. The opposite carrier-transport characteristics of these two materials were leveraged to define the exciton formation zone and thus increase the probability of recombination. The efficiency at practical luminance (100 cd/m{sup 2}) was as high as 20.8%, 47.7 cd/A and 31.2 lm/W, respectively. Furthermore, based on the design concept of this simplified architecture, efficient warmish-white PhOLEDs were developed. Such two-component white organic light-emitting devices exhibited rather stable colors over a wide brightness range and yielded electroluminescence efficiencies of 15.3%, 33.3 cd/A, and 22.7 lm/W in the forward directions.

  9. High surface area mesoporous activated carbon-alginate beads for efficient removal of methylene blue.

    Science.gov (United States)

    Nasrullah, Asma; Bhat, A H; Naeem, Abdul; Isa, Mohamed Hasnain; Danish, Mohammed

    2018-02-01

    High surface area mesoporous activated carbon-alginate (AC-alginate) beads were successfully synthesized by entrapping activated carbon powder derived from Mangosteen fruit peel into calcium-alginate beads for methylene blue (MB) removal from aqueous solution. The structure and surface characteristics of AC-alginate beads were analyzed using Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscopy (SEM) and surface area analysis (S BET ), while thermal properties were tested using thermogravimetric analysis (TGA). The effect of AC-alginate dose, pH of solution, contact time, initial concentration of MB solution and temperature on MB removal was elucidated. The results showed that the maximum adsorption capacity of 230mg/g was achieved for 100mg/L of MB solution at pH 9.5 and temperature 25°C. Furthermore, the adsorption of MB on AC-alginate beads followed well pseudo-second order equation and equilibrium adsorption data were better fitted by the Freundlich isotherm model. The findings reveal the feasibility of AC-alginate beads composite to be used as a potential and low cost adsorbent for removal of cationic dyes. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Nanostructured High Performance Ultraviolet and Blue Light Emitting Diodes for Solid State Lighting

    Energy Technology Data Exchange (ETDEWEB)

    Arto V. Nurmikko; Jung Han

    2007-03-31

    We report on research results in this project which synergize advanced material science approaches with fundamental optical physics concepts pertaining to light-matter interaction, with the goal of solving seminal problems for the development of very high performance light emitting diodes (LEDs) in the blue and near ultraviolet for Solid State Lighting applications. Accomplishments in the duration of the contract period include (i) new means of synthesizing AlGaN and InN quantum dots by droplet heteroepitaxy, (ii) synthesis of AlGaInN nanowires as building blocks for GaN-based microcavity devices, (iii) progress towards direct epitaxial alignment of the dense arrays of nanowires, (iv) observation and measurements of stimulated emission in dense InGaN nanopost arrays, (v) design and fabrication of InGaN photonic crystal emitters, and (vi) observation and measurements of enhanced fluorescence from coupled quantum dot and plasmonic nanostructures. The body of results is presented in this report shows how a solid foundation has been laid, with several noticeable accomplishments, for innovative research, consistent with the stated milestones.

  11. Highly efficient phosphorescent blue and white organic light-emitting devices with simplified architectures

    International Nuclear Information System (INIS)

    Chang, Chih-Hao; Ding, Yong-Shung; Hsieh, Po-Wei; Chang, Chien-Ping; Lin, Wei-Chieh; Chang, Hsin-Hua

    2011-01-01

    Blue phosphorescent organic light-emitting devices (PhOLEDs) with quantum efficiency close to the theoretical maximum were achieved by utilizing a double-layer architecture. Two wide-triplet-gap materials, 1,3-bis(9-carbazolyl)benzene and 1,3,5-tri[(3-pyridyl)-phen-3-yl]benzene, were employed in the emitting and electron-transport layers respectively. The opposite carrier-transport characteristics of these two materials were leveraged to define the exciton formation zone and thus increase the probability of recombination. The efficiency at practical luminance (100 cd/m 2 ) was as high as 20.8%, 47.7 cd/A and 31.2 lm/W, respectively. Furthermore, based on the design concept of this simplified architecture, efficient warmish-white PhOLEDs were developed. Such two-component white organic light-emitting devices exhibited rather stable colors over a wide brightness range and yielded electroluminescence efficiencies of 15.3%, 33.3 cd/A, and 22.7 lm/W in the forward directions.

  12. High-throughput screening for cellobiose dehydrogenases by Prussian Blue in situ formation.

    Science.gov (United States)

    Vasilchenko, Liliya G; Ludwig, Roland; Yershevich, Olga P; Haltrich, Dietmar; Rabinovich, Mikhail L

    2012-07-01

    Extracellular fungal flavocytochrome cellobiose dehydrogenase (CDH) is a promising enzyme for both bioelectronics and lignocellulose bioconversion. A selective high-throughput screening assay for CDH in the presence of various fungal oxidoreductases was developed. It is based on Prussian Blue (PB) in situ formation in the presence of cellobiose (<0.25 mM), ferric acetate, and ferricyanide. CDH induces PB formation via both reduction of ferricyanide to ferrocyanide reacting with an excess of Fe³⁺ (pathway 1) and reduction of ferric ions to Fe²⁺ reacting with the excess of ferricyanide (pathway 2). Basidiomycetous and ascomycetous CDH formed PB optimally at pH 3.5 and 4.5, respectively. In contrast to the holoenzyme CDH, its FAD-containing dehydrogenase domain lacking the cytochrome domain formed PB only via pathway 1 and was less active than the parent enzyme. The assay can be applied on active growing cultures on agar plates or on fungal culture supernatants in 96-well plates under aerobic conditions. Neither other carbohydrate oxidoreductases (pyranose dehydrogenase, FAD-dependent glucose dehydrogenase, glucose oxidase) nor laccase interfered with CDH activity in this assay. Applicability of the developed assay for the selection of new ascomycetous CDH producers as well as possibility of the controlled synthesis of new PB nanocomposites by CDH are discussed. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  13. Highly Efficient White Organic Light Emitting Diodes Using New Blue Fluorescence Emitter.

    Science.gov (United States)

    Kim, Seungho; Kim, Beomjin; Lee, Jaehyun; Yu, Young-Jun; Park, Jongwook

    2015-07-01

    Two different emitting compounds, 1-[1,1';3',1"]Terphenyl-5'-yl-6-(10-[1,1';3',1"]terpheny-5'-yl- anthracen-9-yl)-pyrene (TP-AP-TP) and Poly-phenylene vinylene derivative (PDY 132) were used to white OLED device. By incorporating adjacent blue and yellow emitting layers in a multi-layered structure, highly efficient white emission has been attained. The device was fabricated with a hybrid configuration structure: ITO/PEDOT (40 nm)/PDY-132 (8-50 nm)/ NPB (10 nm)/TP-AP-TP (30 nm)/Alq3 (20 nm)/LiF (1 nm)/Al (200 nm). After fixing TP-AP-TP thickness of 30 nm by evaporation, PDY-132 thickness varied with 8, 15, 35, and 50 nm by spin coating in device. The luminance efficiency of the white devices at 10 mA/cm2 were 2.93 cd/A-6.55 cd/A. One of white devices showed 6.55 cd/A and white color of (0.290, 0.331).

  14. High-Performance CuInS 2 Quantum Dot Laminated Glass Luminescent Solar Concentrators for Windows

    Energy Technology Data Exchange (ETDEWEB)

    Bergren, Matthew R. [UbiQD, Inc., Los Alamos, New Mexico 87544, United States; Makarov, Nikolay S. [UbiQD, Inc., Los Alamos, New Mexico 87544, United States; Ramasamy, Karthik [UbiQD, Inc., Los Alamos, New Mexico 87544, United States; Jackson, Aaron [UbiQD, Inc., Los Alamos, New Mexico 87544, United States; Guglielmetti, Rob [National Renewable Energy Laboratory, Golden, Colorado 80401, United States; McDaniel, Hunter [UbiQD, Inc., Los Alamos, New Mexico 87544, United States

    2018-01-30

    Building-integrated sunlight harvesting utilizing laminated glass luminescent solar concentrators (LSCs) is proposed. By incorporating high quantum yield (>90%), NIR-emitting CuInS2/ZnS quantum dots into the polymer interlayer between two sheets of low-iron float glass, a record optical efficiency of 8.1% is demonstrated for a 10 cm x 10 cm device that transmits ~44% visible light. After completing prototypes by attaching silicon solar cells along the perimeter of the device, the electrical power conversion efficiency was certified at 2.2% with a black background and at 2.9% using a reflective substrate. This 'drop-in' LSC solution is particularly attractive because it fits within the existing glazing industry value chain with only modest changes to typical glazing products. Performance modeling predicts >1 GWh annual electricity production for a typical urban skyscraper in most major U.S. cities, enabling significant energy cost savings and potentially 'net-zero' buildings.

  15. Highly efficient upconversion luminescence in hexagonal NaYF4:Yb3+, Er3+ nanocrystals synthesized by a novel reverse microemulsion method

    Science.gov (United States)

    Gunaseelan, M.; Yamini, S.; Kumar, G. A.; Senthilselvan, J.

    2018-01-01

    A new reverse microemulsion system is proposed for the first time to synthesize NaYF4:Yb,Er nanocrystals, which demonstrated high upconversion emission in 550 and 662 nm at 980 nm diode laser excitation. The reverse microemulsion (μEs) system is comprised of CTAB and oleic acid as surfactant and 1-butanol co-surfactant and isooctane oil phase. The surfactant to water ratio is able to tune the microemulsion droplet size from 14 to 220 nm, which eventually controls the crystallinity and particulate morphology of NaYF4:Yb,Er. Also, the microemulsion precursor and calcination temperature plays certain role in transforming the cubic NaYF4:Yb,Er to highly luminescent hexagonal crystal structured upconversion material. Single phase hexagonal NaYF4:YbEr nanorod prepared by water-in-oil reverse microemulsion (μEs) gives intense red upconversion emission. Both nanosphere and nanorod shaped NaYF4:Yb,Er was obtained, but nanorod morphology resulted an enhanced upconversion luminescence. The structural, morphological, thermal and optical luminescence properties of the NaYF4:Yb,Er nanoparticles are discussed in detail by employing powder X-ray diffraction, dynamic light scattering, high resolution electron microscopy, TGA-DTA, UV-DRS, FTIR and photoluminescence spectroscopy. Intense upconversion emission achieved in the microemulsion synthesized NaYF4:Yb3+,Er3+ nanocrystal can make it as useful optical phosphor for solar cell applications.

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

    International Nuclear Information System (INIS)

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

    2004-01-01

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

  17. High speed visible light communication using blue GaN laser diodes

    Science.gov (United States)

    Watson, S.; Viola, S.; Giuliano, G.; Najda, S. P.; Perlin, P.; Suski, T.; Marona, L.; Leszczyński, M.; Wisniewski, P.; Czernecki, R.; Targowski, G.; Watson, M. A.; White, H.; Rowe, D.; Laycock, L.; Kelly, A. E.

    2016-10-01

    GaN-based laser diodes have been developed over the last 20 years making them desirable for many security and defence applications, in particular, free space laser communications. Unlike their LED counterparts, laser diodes are not limited by their carrier lifetime which makes them attractive for high speed communication, whether in free space, through fiber or underwater. Gigabit data transmission can be achieved in free space by modulating the visible light from the laser with a pseudo-random bit sequence (PRBS), with recent results approaching 5 Gbit/s error free data transmission. By exploiting the low-loss in the blue part of the spectrum through water, data transmission experiments have also been conducted to show rates of 2.5 Gbit/s underwater. Different water types have been tested to monitor the effect of scattering and to see how this affects the overall transmission rate and distance. This is of great interest for communication with unmanned underwater vehicles (UUV) as the current method using acoustics is much slower and vulnerable to interception. These types of laser diodes can typically reach 50-100 mW of power which increases the length at which the data can be transmitted. This distance could be further improved by making use of high power laser arrays. Highly uniform GaN substrates with low defectivity allow individually addressable laser bars to be fabricated. This could ultimately increase optical power levels to 4 W for a 20-emitter array. Overall, the development of GaN laser diodes will play an important part in free space optical communications and will be vital in the advancement of security and defence applications.

  18. Direct sequencing of mitochondrial DNA detects highly divergent haplotypes in blue marlin (Makaira nigricans).

    Science.gov (United States)

    Finnerty, J R; Block, B A

    1992-06-01

    We were able to differentiate between species of billfish (Istiophoridae family) and to detect considerable intraspecific variation in the blue marlin (Makaira nigricans) by directly sequencing a polymerase chain reaction (PCR)-amplified, 612-bp fragment of the mitochondrial cytochrome b gene. Thirteen variable nucleotide sites separated blue marlin (n = 26) into 7 genotypes. On average, these genotypes differed by 5.7 base substitutions. A smaller sample of swordfish from an equally broad geographic distribution displayed relatively little intraspecific variation, with an average of 1.3 substitutions separating different genotypes. A cladistic analysis of blue marlin cytochrome b variants indicates two major divergent evolutionary lines within the species. The frequencies of these two major evolutionary lines differ significantly between Atlantic and Pacific ocean basins. This finding is important given that the Atlantic stocks of blue marlin are considered endangered. Migration from the Pacific can help replenish the numbers of blue marlin in the Atlantic, but the loss of certain mitochondrial DNA haplotypes in the Atlantic due to overfishing probably could not be remedied by an influx of Pacific fish because of their absence in the Pacific population. Fishery management strategies should attempt to preserve the genetic diversity within the species. The detection of DNA sequence polymorphism indicates the utility of PCR technology in pelagic fishery genetics.

  19. Highly efficient blue and warm white organic light-emitting diodes with a simplified structure

    International Nuclear Information System (INIS)

    Li, Xiang-Long; Chen, Dongcheng; Cai, Xinyi; Liu, Ming; Cao, Yong; Su, Shi-Jian; Ouyang, Xinhua; Ge, Ziyi

    2016-01-01

    Two blue fluorescent emitters were utilized to construct simplified organic light-emitting diodes (OLEDs) and the remarkable difference in device performance was carefully illustrated. A maximum current efficiency of 4.84 cd A"−"1 (corresponding to a quantum efficiency of 4.29%) with a Commission Internationale de l’Eclairage (CIE) coordinate of (0.144, 0.127) was achieved by using N,N-diphenyl-4″-(1-phenyl-1H-benzo[d]imidazol-2-yl)-[1, 1′:4′, 1″-terphenyl]-4-amine (BBPI) as a non-doped emission layer of the simplified blue OLEDs without carrier-transport layers. In addition, simplified fluorescent/phosphorescent (F/P) hybrid warm white OLEDs without carrier-transport layers were fabricated by utilizing BBPI as (1) the blue emitter and (2) the host of a complementary yellow phosphorescent emitter (PO-01). A maximum current efficiency of 36.8 cd A"−"1 and a maximum power efficiency of 38.6 lm W"−"1 were achieved as a result of efficient energy transfer from the host to the guest and good triplet exciton confinement on the phosphorescent molecules. The blue and white OLEDs are among the most efficient simplified fluorescent blue and F/P hybrid white devices, and their performance is even comparable to that of most previously reported complicated multi-layer devices with carrier-transport layers. (paper)

  20. Fabrication and Spectral Properties of Wood-Based Luminescent Nanocomposites

    Directory of Open Access Journals (Sweden)

    Xianjun Li

    2014-01-01

    Full Text Available Pressure impregnation pretreatment is a conventional method to fabricate wood-based nanocomposites. In this paper, the wood-based luminescent nanocomposites were fabricated with the method and its spectral properties were investigated. The results show that it is feasible to fabricate wood-based luminescent nanocomposites using microwave modified wood and nanophosphor powders. The luminescent strength is in positive correlation with the amount of phosphor powders dispersed in urea-formaldehyde resin. Phosphors absorb UV and blue light efficiently in the range of 400–470 nm and show a broad band of bluish-green emission centered at 500 nm, which makes them good candidates for potential blue-green luminescent materials.

  1. High pressure luminescence studies of localized excitations in ZnS doped with Pb2+ and Mn2+

    International Nuclear Information System (INIS)

    House, G.L.; Drickamer, H.G.

    1977-01-01

    High pressure luminescence measurements have been made on ZnS doped with Pb +2 and Mn +2 . The data include changes in peak energy and shape, integrated intensities, and lifetimes. These localized emissions are treated in terms of a single configuration coordinate model. For Pb +2 the emission peak shifted to lower energy by a moderate amount and narrowed. For excitation in the Pb +2 absorption the intensity was independent of pressure, which is consistent with the fact that the energy barrier for radiationless return to the ground state was high at all pressures. For excitation in the ZnS absorption edge the intensity decreased significantly with pressure above about 80 kbar. Data on shifts of the conduction band with pressure would indicate that one is approaching a transition from a direct to indirect transition at high pressure so that decrease in emission intensity may be associated with decreased absorption efficiency. The Mn+ 2 emission peak shifted strongly to lower energy with increasing pressure. The direction and magnitude of the shift were consistent with the predictions of ligand field theory. The intensity doubled in 100 kbar, while the lifetime decreased by roughly a factor of 2. These results could be described in terms of a model for a phonon assisted transition. In addition, peak location, intensity, and lifetime measurements were made on ZnS:Pb:Mn. There is clear evidence of energy transfer by exchange, but in addition there is a nonradiative process in the doubly doped crystal which affects both intensities and lifetimes

  2. Unclonable Security Codes Designed from Multicolor Luminescent Lanthanide-Doped Y2O3 Nanorods for Anticounterfeiting.

    Science.gov (United States)

    Kumar, Pawan; Nagpal, Kanika; Gupta, Bipin Kumar

    2017-04-26

    The duplicity of important documents has emerged as a serious problem worldwide. Therefore, many efforts have been devoted to developing easy and fast anticounterfeiting techniques with multicolor emission. Herein, we report the synthesis of multicolor luminescent lanthanide-doped Y 2 O 3 nanorods by hydrothermal method and their usability in designing of unclonable security codes for anticounterfeiting applications. The spectroscopic features of nanorods are probed by photoluminescence spectroscopy. The Y 2 O 3 :Eu 3+ , Y 2 O 3 :Tb 3+ , and Y 2 O 3 :Ce 3+ nanorods emit hypersensitive red (at 611 nm), strong green (at 541 nm), and bright blue (at 438 nm) emissions at 254, 305, and 381 nm, respectively. The SEM and TEM/HRTEM results reveal that these nanorods have diameter and length in the range of 80-120 nm and ∼2-5 μm, respectively. The two-dimensional spatially resolved photoluminescence intensity distribution in nanorods is also investigated by using confocal photoluminescence microscopic technique. Further, highly luminescent unclonable security codes are printed by a simple screen printing technique using luminescent ink fabricated from admixing of lanthanide doped multicolor nanorods in PVC medium. The prospective use of these multicolor luminescent nanorods provide a new opportunity for easily printable, highly stable, and unclonable multicolor luminescent security codes for anti-counterfeiting applications.

  3. Is Green better than Blue? The Danish JHA opt-out and the Unilateral attempt to attrack highly skilled labour

    DEFF Research Database (Denmark)

    Wind, Marlene; Adamo, Silvia

    2015-01-01

    In 20–30 years Denmark will, just like the rest of the EU, be in need of an increasing number of highly skilled workers from outside the EU to sustain its welfare society. While the EU has adopted a common Blue Card aiming at making it possible for foreign workers to live and work in most of the EU......, Denmark has, due to its opt-out in Justice and Home Affairs, chosen its own Green Card Scheme. This article looks into this choice and compares the recent Danish attempt to attract high skilled workers with the Blue Card directive. It analyses the differences and similarities between the two schemes...... and investigates why initiatives to attract highly skilled workers have not been successful at either the Danish nor the European level....

  4. Ultrasensitive direct competitive FLISA using highly luminescent quantum dot beads for tuning affinity of competing antigens to antibodies

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Sicheng; Zhou, Yaofeng; Huang, Xiaolin [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Yu, Ruijin [College of Science, Northwest A& F University, Yangling, Shaanxi 712100 (China); Lai, Weihua [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China); Xiong, Yonghua, E-mail: yhxiongchen@163.com [State Key Laboratory of Food Science and Technology, Nanchang University, Nanchang 330047 (China)

    2017-06-15

    Herein, for the first time we report a novel direct competitive fluorescence-linked immunosorbent assay (dcFLISA) for the ultrasensitive detection of ochratoxin A (OTA) by introducing a large size polymer beads loaded with quantum dots (QBs) as carrier of competing antigen for decreasing binding affinity to antibody and enhancing the fluorescent signal intensity. When using 255 nm QBs as carrier of competing antigen, the equilibrium dissociation constant of QB based competing antigen to antibodies can be tuned to 100 times higher than that of the horseradish peroxidase (HRP) based competing antigen by controlling labeled amounts of antigen on the surface of QBs. Various parameters that influenced the sensitivity of dcFLISA were investigated and optimized. Under optimum detection parameters, the dynamic linear range of developed dcFLISA for detecting OTA was established at 0.05 pg/mL to 1.56 pg/mL with a half maximal inhibitory concentration at 0.14 ± 0.04 pg/mL (n = 5), which is three orders of magnitude lower than that of conventional HRP-based dcELISA (0.24 ng/mL). The developed FLISA is also highly accurate, reliable, and shows no cross reaction to other mycotoxins. In summary, the proposed method offers a straightforward approach to improve the sensitivity of direct competitive immunoassay for trace small chemical molecule detection in food quality control, environmental monitoring, and clinical diagnosis. - Highlights: • Highly luminescent QBs were used as a carrier of competing antigen for ultrasensitive detection of OTA. • It is the first time to use a large size QBs as a carrier for tuning affinity of competing antigen to antibodies. • IC{sub 50} value of QB-based dcFLISA is three orders of magnitude lower than that of HRP-based dcELISA.

  5. Ultrasensitive direct competitive FLISA using highly luminescent quantum dot beads for tuning affinity of competing antigens to antibodies

    International Nuclear Information System (INIS)

    Xiong, Sicheng; Zhou, Yaofeng; Huang, Xiaolin; Yu, Ruijin; Lai, Weihua; Xiong, Yonghua

    2017-01-01

    Herein, for the first time we report a novel direct competitive fluorescence-linked immunosorbent assay (dcFLISA) for the ultrasensitive detection of ochratoxin A (OTA) by introducing a large size polymer beads loaded with quantum dots (QBs) as carrier of competing antigen for decreasing binding affinity to antibody and enhancing the fluorescent signal intensity. When using 255 nm QBs as carrier of competing antigen, the equilibrium dissociation constant of QB based competing antigen to antibodies can be tuned to 100 times higher than that of the horseradish peroxidase (HRP) based competing antigen by controlling labeled amounts of antigen on the surface of QBs. Various parameters that influenced the sensitivity of dcFLISA were investigated and optimized. Under optimum detection parameters, the dynamic linear range of developed dcFLISA for detecting OTA was established at 0.05 pg/mL to 1.56 pg/mL with a half maximal inhibitory concentration at 0.14 ± 0.04 pg/mL (n = 5), which is three orders of magnitude lower than that of conventional HRP-based dcELISA (0.24 ng/mL). The developed FLISA is also highly accurate, reliable, and shows no cross reaction to other mycotoxins. In summary, the proposed method offers a straightforward approach to improve the sensitivity of direct competitive immunoassay for trace small chemical molecule detection in food quality control, environmental monitoring, and clinical diagnosis. - Highlights: • Highly luminescent QBs were used as a carrier of competing antigen for ultrasensitive detection of OTA. • It is the first time to use a large size QBs as a carrier for tuning affinity of competing antigen to antibodies. • IC_5_0 value of QB-based dcFLISA is three orders of magnitude lower than that of HRP-based dcELISA.

  6. Non-Doped Sky-Blue OLEDs Based on Simple Structured AIE Emitters with High Efficiencies at Low Driven Voltages.

    Science.gov (United States)

    Islam, Amjad; Zhang, Dongdong; Peng, Ruixiang; Yang, Rongjuan; Hong, Ling; Song, Wei; Wei, Qiang; Duan, Lian; Ge, Ziyi

    2017-09-05

    Blue organic light-emitting diodes (OLEDs) are necessary for flat-panel display technologies and lighting applications. To make more energy-saving, low-cost and long-lasting OLEDs, efficient materials as well as simple structured devices are in high demand. However, a very limited number of blue OLEDs achieving high stability and color purity have been reported. Herein, three new sky-blue emitters, 1,4,5-triphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEI), 1-(4-methoxyphenyl)-4,5-diphenyl-2-(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (TPEMeOPhI) and 1-phenyl-2,4,5-tris(4-(1,2,2-triphenylvinyl)phenyl)-1H-imidazole (3TPEI), with a combination of imidazole and tetraphenylethene groups, have been developed. High photoluminescence quantum yields are obtained for these materials. All derivatives have demonstrated aggregation-induced emission (AIE) behavior, excellent thermal stability with high decomposition and glass transition temperatures. Non-doped sky-blue OLEDs with simple structure have been fabricated employing these materials as emitters and realized high efficiencies of 2.41 % (4.92 cd A -1 , 2.70 lm W -1 ), 2.16 (4.33 cd A -1 , 2.59 lm W -1 ) and 3.13 % (6.97 cd A -1 , 4.74 lm W -1 ) for TPEI, TPEMeOPhI and 3TPEI, with small efficiency roll-off. These are among excellent results for molecules constructed from the combination of imidazole and TPE reported so far. The high performance of a 3TPEI-based device shows the promising potential of the combination of imidazole and AIEgen for synthesizing efficient electroluminescent materials for OLED devices. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Highly luminescent colloidal Eu(3)+-doped KZnF(3) nanoparticles for the selective and sensitive detection of Cu(II) ions.

    Science.gov (United States)

    Sarkar, Shyam; Chatti, Manjunath; Mahalingam, Venkataramanan

    2014-03-17

    This article describes a green synthetic approach to prepare water dispersible perovskite-type Eu3+-doped KZnF3 nanoparticles, carried out using environmentally friendly microwave irradiation at low temperature (85 8C) with water as a solvent. Incorporation of Eu3+ ions into the KZnF3 matrix is confirmed by strong red emission upon ultraviolet (UV) excitation of the nanoparticles. The nanoparticles are coated with poly(acrylic acid) (PAA), which enhances the dispersibility of the nanoparticles in hydrophilic solvents. The strong red emission from Eu3+ ions is selectively quenched upon addition of CuII ions, thus making the nanoparticles a potential CuII sensing material. This sensing ability is highly reversible by the addition of ethylenediaminetetraacetic acid (EDTA), with recovery of almost 90% of the luminescence. If the nanoparticles are strongly attached to a positively charged surface, dipping the surface in a CuII solution leads to the quenching of Eu3+ luminescence, which can be recovered after dipping in an EDTA solution. This process can be repeated for more than five cycles with only a slight decrease in the sensing ability. In addition to sensing, the strong luminescence from Eu3+-doped KZnF3 nanoparticles could be used as a tool for bioimaging.

  8. Feldspar, Infrared Stimulated Luminescence

    DEFF Research Database (Denmark)

    Jain, Mayank

    2014-01-01

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

  9. Highly Sensitive Luminescence Assessment of Bile Acid Using a Balofloxacin-Europium(III) Probe in Micellar Medium

    International Nuclear Information System (INIS)

    Cai, Huan; Zhao, Fang; Si, Hailin; Zhang, Shuaishuai; Wang, Chunchun; Qi, Peirong

    2012-01-01

    A novel and simple method of luminescence enhancement effect for the determination of trace amounts of bile acid was proposed. The procedure was based on the luminescence intensity of the balofloxacin-europium(III) complex that could be strongly enhanced by bile acid in the presence of sodium dodecyl benzene sulfonate (SDBS). Under the optimum conditions, the enhanced luminescence intensity of the system exhibited a good linear relationship with the bile acid concentration in the range 5.0 Χ 10 -9 - 7.0 Χ 10 -7 mol L -1 with a detection limit of 1.3 Χ 10 -9 mol L.1 (3σ). The relative standard deviation (RSD) was 1.7% (n = 11) for 5.0 Χ 10 -8 mol L -1 bile acid. The applicability of the method to the determination of bile acid was demonstrated by investigating the effect of potential interferences and by analyzing human serum and urine samples. The possible enhancement mechanism of luminescence intensity in balofloxacin-europium(III)-bile acid-SDBS system was also discussed briefly

  10. Photophysical studies of highly luminescent europium(III) and terbium(III) complexes functionalized with amino and mercapto groups

    Energy Technology Data Exchange (ETDEWEB)

    Souza, E.R.; Monteiro, J.H.S.K.; Mazali, I.O.; Sigoli, F.A., E-mail: fsigoli@iqm.unicam.br

    2016-02-15

    This work proposes the replacement of coordinated-water molecules from the precursor complexes [Ln(aba){sub 3}(H{sub 2}O)] and [Ln(tta){sub 3}(H{sub 2}O){sub 2}], (Ln=Eu{sup 3+}, Gd{sup 3+} or Tb{sup 3+}, aba{sup −}=aminobenzoate, tta{sup −}=thenoyltrifluoroacetonate) by the ligands mercaptobenzoate (mba{sup −}), mercaptopropionate (mpa{sup −}), phenanthroline (phen), dimethylformamide (dmf) and acetoacetanilide (aaa{sup −}), leading to anionic or neutral amino (–NH{sub 2}) or mercapto (–SH) functionalized-lantanides (III) complexes with reasonable emission quantum yields for potential application on fluorescence microscopy of biological moieties. The complexes photophysical properties were studied using luminescence spectroscopy and theoretical models to determine the transfer and back energy transfer rates and quantum yields, that were compared with experimental ones. The anionic complexes [Eu(tta){sub 3}(L)]{sup −} showed high quantum yield values and their sensitization efficiency are in the range of 39–81%. The overlay of the ground state geometries, obtained from the Sparkle/PM3 model, of the complexes [Eu(tta){sub 3}(aba)]{sup −}, [Eu(tta){sub 3}(mba)]{sup −} and [Eu(tta){sub 3}(mpa)]{sup −}, suggest similar coordination polyhedrons occupied by the europium(III). The highest transfer rates T→{sup 5}D{sub 1,0} were obtained for the anionic complexes [Eu(tta){sub 3}(L)]{sup −} which might be a result of the low triplet level energies and R{sub L} values. - Highlights: • Lanthanides functionalized-complexes. • Free mercapto and amino groups. • Covalence degree of Eu-ligands. • Energy transfer rates. • Intrinsic and absolute quantum yields and sensitization.

  11. Oxide/polymer nanocomposites as new luminescent materials

    Science.gov (United States)

    Vollath, D.; Szabó, D. V.; Schlabach, S.

    2004-06-01

    It is demonstrated that nanocomposites, consisting of an electrically insulating oxide core and PMMA coating exhibit strong luminescence. This luminescence is connected to the interface, where PMMA is bond via a carboxylate bonding to the surface. In this case, luminescence is originated at the carbonyl group of the coating polymer. With decreasing particle size, this emission shows a blue shift, following a law inversely the ones found for quantum confinement systems. For semi-conducting oxides, such as ZnO, this interface related emission is found additionally to quantum confinement phenomena.

  12. Guided Growth of Horizontal ZnSe Nanowires and their Integration into High-Performance Blue-UV Photodetectors.

    Science.gov (United States)

    Oksenberg, Eitan; Popovitz-Biro, Ronit; Rechav, Katya; Joselevich, Ernesto

    2015-07-15

    Perfectly aligned horizontal ZnSe nano-wires are obtained by guided growth, and easily integrated into high-performance blue-UV photodetectors. Their crystal phase and crystallographic orientation are controlled by the epitaxial relations with six different sapphire planes. Guided growth paves the way for the large-scale integration of nanowires into optoelectronic devices. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2017-03-15

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

  14. Novel and easy access to highly luminescent Eu and Tb doped ultra-small CaF2, SrF2 and BaF2 nanoparticles - structure and luminescence.

    Science.gov (United States)

    Ritter, Benjamin; Haida, Philipp; Fink, Friedrich; Krahl, Thoralf; Gawlitza, Kornelia; Rurack, Knut; Scholz, Gudrun; Kemnitz, Erhard

    2017-02-28

    A universal fast and easy access at room temperature to transparent sols of nanoscopic Eu 3+ and Tb 3+ doped CaF 2 , SrF 2 and BaF 2 particles via the fluorolytic sol-gel synthesis route is presented. Monodisperse quasi-spherical nanoparticles with sizes of 3-20 nm are obtained with up to 40% rare earth doping showing red or green luminescence. In the beginning luminescence quenching effects are only observed for the highest content, which demonstrates the unique and outstanding properties of these materials. From CaF 2 :Eu10 via SrF 2 :Eu10 to BaF 2 :Eu10 a steady increase of the luminescence intensity and lifetime occurs by a factor of ≈2; the photoluminescence quantum yield increases by 29 to 35% due to the lower phonon energy of the matrix. The fast formation process of the particles within fractions of seconds is clearly visualized by exploiting appropriate luminescence processes during the synthesis. Multiply doped particles are also available by this method. Fine tuning of the luminescence properties is achieved by variation of the Ca-to-Sr ratio. Co-doping with Ce 3+ and Tb 3+ results in a huge increase (>50 times) of the green luminescence intensity due to energy transfer Ce 3+ → Tb 3+ . In this case, the luminescence intensity is higher for CaF 2 than for SrF 2 , due to a lower spatial distance of the rare earth ions.

  15. One-pot synthesis of highly luminescent InP/ZnS nanocrystals without precursor injection.

    Science.gov (United States)

    Li, Liang; Reiss, Peter

    2008-09-03

    InP/ZnS core/shell nanocrystals are prepared using a single-step heating-up method relying on the difference in reactivity of the applied InP and ZnS precursors. The obtained particles exhibit size-dependent emission in the range of 480-590 nm, a fluorescence quantum yield of 50-70%, and high photostability.

  16. The effect of high pressure on the luminescent properties of coumarin 153

    CERN Document Server

    Li Hong; He Li Ming; Wu Shi Kang; Li Yi; Yang Guo Qiang

    2002-01-01

    A dual-fluorescence emitting behaviour of coumarin 153 powder has been detected at high pressure while at ambient pressure the dye exhibits only single-band emission. Because of the strong electron-withdrawal group at site 7, these two fluorescent peaks can be ascribed to local excited state emission and charge transfer state emission, respectively.

  17. Highly luminescent pure-red-emitting fluorinated β-diketonate europium(III) complex for full solution-processed OLEDs

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Joao P. [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, Coimbra P-3004-516 (Portugal); Serviço de Medicina Nuclear, SESARAM E.P.E., Avenida Luís de Camões 57, Funchal 9004-514, Madeira (Portugal); Martín-Ramos, Pablo [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, Coimbra P-3004-516 (Portugal); Higher Technical School of Telecommunications Engineering, Universidad de Valladolid, Campus Miguel Delibes, Paseo Belén 15, Valladolid 47011 (Spain); Coya, Carmen, E-mail: carmen.coya@urjc.es [Escuela Superior de Ciencias Experimentales y Tecnología (ESCET), Universidad Rey Juan Carlos, Madrid 28933 (Spain); Silva, Manuela Ramos [CEMDRX, Physics Department, Universidade de Coimbra, Rua Larga, Coimbra P-3004-516 (Portugal); Eusebio, M. Ermelinda S. [Chemistry Department, Faculdade de Ciências e Tecnologia, Universidade de Coimbra, Coimbra P-3004-535 (Portugal); Andrés, Alicia de [Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (CSIC), Cantoblanco, Madrid 28049 (Spain); Álvarez, Ángel L. [Escuela Superior de Ciencias Experimentales y Tecnología (ESCET), Universidad Rey Juan Carlos, Madrid 28933 (Spain); Martín-Gil, Jesús [Advanced Materials Laboratory, ETSIIAA, Universidad de Valladolid, Avenida de Madrid 44, Palencia 34004 (Spain)

    2015-03-15

    Current manufacturing technologies for OLEDs involve the use of expensive high vacuum techniques and call for thermal stability requirements which are not fulfilled by many materials. These problems disappear when the OLED films are deposited directly from solution. In this study, we have designed, synthesized and characterized a novel octacoordinated complex, Tris(1-(4-chlorophenyl)-4,4,4-trifluoro-1, 3-butanedionate)mono(bathophenanthroline) europium(III), to be used as a “complex-only” emissive layer in wet-processed OLEDs. Upon excitation in the UV region, very efficient energy transfer from the ligands to Eu{sup 3+} takes place, giving rise to intense red emission with very high monochromaticity (R=19), both in powder and as a thin film. The decay times of 754 µs (powder) and 620 µs (thin film) are comparable to those of the most efficient Eu{sup 3+} β-diketonate complexes reported to date. The same energy transfer leading to saturated red and narrow emission is also observed in the OLED device (glass/ITO/PEDOT:PSS/[Eu(cbtfa){sub 3}(bath)]/Ca/Al) when biased at >5.2 V. Its high quantum efficiency (∼60%), good thermal stability up to 200 °C and adequate thin film forming properties make this material a promising chromophore for cost-effective OLEDs. - Highlights: • A highly fluorinated europium(III) octacoordinated complex, [Eu(cbtfa)3(bath)], has been synthesized and its structure elucidated by single crystal X-ray diffraction. • The chosen coordination environment is well-suited for sensitizing the luminescence of the Eu{sup 3+} ion, achieving very efficient energy transfer from the organic ligands (excited in the UV region) to the rare earth ion, leading to highly efficient (Q∼60% in crystalline powder and Q∼50% in thin film) and saturated red photoluminescence. • The material has also been integrated into a single active layer, full solution-processed OLED, with ITO/PEDOT:PSS/[Eu(cbtfa)3(bath)]/ Ca/Al structure.

  18. Dosimetry of Al2O3 optically stimulated luminescent dosimeter at high energy photons and electrons

    Science.gov (United States)

    Yusof, M. F. Mohd; Joohari, N. A.; Abdullah, R.; Shukor, N. S. Abd; Kadir, A. B. Abd; Isa, N. Mohd

    2018-01-01

    The linearity of Al2O3 OSL dosimeters (OSLD) were evaluated for dosimetry works in clinical photons and electrons. The measurements were made at a reference depth of Zref according to IAEA TRS 398:2000 codes of practice at 6 and 10 MV photons and 6 and 9 MeV electrons. The measured dose was compared to the thermoluminescence dosimeters (TLD) and ionization chamber commonly used for dosimetry works for higher energy photons and electrons. The results showed that the measured dose in OSL dosimeters were in good agreement with the reported by the ionization chamber in both high energy photons and electrons. A reproducibility test also reported excellent consistency of readings with the OSL at similar energy levels. The overall results confirmed the suitability of OSL dosimeters for dosimetry works involving high energy photons and electrons in radiotherapy.

  19. Polar-solvent-free colloidal synthesis of highly luminescent alkylammonium lead halide perovskite nanocrystals

    Science.gov (United States)

    Vybornyi, Oleh; Yakunin, Sergii; Kovalenko, Maksym V.

    2016-03-01

    A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2.A novel synthesis of hybrid organic-inorganic lead halide perovskite nanocrystals (CH3NH3PbX3, X = Br or I) that does not involve the use of dimethylformamide or other polar solvents is presented. The reaction between methylamine and PbX2 salts is conducted in a high-boiling nonpolar solvent (1-octadecene) in the presence of oleylamine and oleic acid as coordinating ligands. The resulting nanocrystals are characterized by high photoluminescence quantum efficiencies of 15-50%, outstanding phase purity and tunable shapes (nanocubes, nanowires, and nanoplatelets). Nanoplatelets spontaneously assemble into micrometer-length wires by face-to-face stacking. In addition, we demonstrate amplified spontaneous emission from thin films of green-emitting CH3NH3PbBr3 nanowires with low pumping thresholds of 3 μJ cm-2. Electronic supplementary information (ESI) available: Materials and methods, additional figures. See DOI: 10.1039/c5nr06890h

  20. High-pressure cell for luminescence studies of condensed phases at low temperatures

    International Nuclear Information System (INIS)

    Variano, B.F.; Brenner, H.C.; Daniels, W.B.

    1986-01-01

    A clamped optical cell for high-pressure low-temperature fluorescence and phosphorescence studies is described. A particular innovation is the use of a bifurcated fiber-optic lightguide to enable sample illumination and emission collection with a single optical window. This very simple type of cell is adaptable to a variety of optical setups and is easily assembled and disassembled for sample mounting

  1. Luminescence of CsPbBr3 films under high-power excitation

    OpenAIRE

    高橋, 一彰; 斎藤, 忠昭; 近藤, 新一; 浅田, 拡志

    2004-01-01

    Highly excited photoluminescence of CsPbBr3 has been measured for thin films prepared by crystallization from the amorphous phase into microcrystalline/ polycrystalline states. With the increase of excitation intensity, there occurs jumping of the dominant emission band from a free-exciton band to a new band originating from exciton-exciton inelastic collision. Stimulated emission is observed for the new band at very low threshold excitation intensities of the order of 10kW/cm2.

  2. Luminescence of a new class of UV-blue-emitting phosphors MSi2O2-deltaN2+2/3delta:Ce3+ (M = Ca, Sr, Ba)

    NARCIS (Netherlands)

    Li, Y.Q.; With, de G.; Hintzen, H.T.J.M.

    2005-01-01

    The luminescence properties of Ce3+,Na+-codoped MSi2O22dN2+2/3d (M 5 Ca, Sr, Ba) are reported. The undoped and Ce3+,Na+-codoped MSi2O22dN2+2/3d powders were prepared by a solid-state reaction at temperatures between 1300–1400 uC under N2–H2 (10%) atmosphere in the system MO–SiO2–Si3N4 (M 5 Ca, Sr,

  3. LUMINESCENCE DETERMINATION OF ETODOLAC

    Directory of Open Access Journals (Sweden)

    A. V. Yegorova

    2015-02-01

    Full Text Available A highly sensitive, simple and rapid method for determination of non-steroidal anti- inflammatory drug – etodolac (Et in washings from surfaces of pharmaceutical equipment have been proposed. The intensity of native luminescence of water-n-propanol solutions of etodolac (λex= 274 nm; λlum= 350 nm was used as the analytical signal. The calibration graph is linear in the concentration range 0.014-2.3 μg/ml, the limit of detection is 0.5 ng/ml.

  4. Luminescence and electrification in a flow of dielectric liquids through narrow channels

    Science.gov (United States)

    Margulis, M. A.; Pil'Gunov, V. N.

    2009-08-01

    Blue-violet luminescence was observed in a mineral oil, which appeared under hydrodynamic cavitation conditions in a channel orifice 1 mm in diameter in a transparent throttling device at inlet pressures higher than 2 MPa. The appearance of electric pulses when a dielectric liquid flew through a thin channel orifice was observed much earlier than luminescence arose. A device for continuously scanning electric potential along a flow without disturbing it was developed. According to the oscillograms obtained, the electric signal was high-frequency, could not be synchronized, and its separate peaks reached 1000 mV. Light emission flux decreased as the temperature of the liquid increased to 30-35°C and inlet pressure grew. The appearance of luminescence and its intensity depended on the sharpness of the entrance edge of the throttle. Studies of hydrodynamic luminescence revealed hysteresis of light emission. A mechanism of localized light emission based on an important role played by electrokinetic phenomena was suggested.

  5. Fabrication of fluorescent composite with ultrafast aqueous synthesized high luminescent CdTe quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Lei, E-mail: mejswu@ust.hk; Chen, Haibin, E-mail: mejswu@ust.hk, E-mail: mejswu@ust.hk; Wu, Jingshen, E-mail: mejswu@ust.hk, E-mail: mejswu@ust.hk [Department of Mechanical and Aerospace Engineering, The Hong Kong University of Science and Technology, Hong Kong and Fok Ying Tung Graduate School, The Hong Kong University of Science and Technology (Hong Kong); Bi, Xianghong, E-mail: takubatch@gmail.com [Fok Ying Tung Graduate School, The Hong Kong University of Science and Technology (Hong Kong)

    2014-05-15

    Without precursor preparation, inert gas protection and enormous amount of additives and reductants, CdTe quantum dots (QDs) can be rapidly synthesized with high quality. A 600 nm photoluminescence peak wavelength could be obtained within 1 hour's refluxing through minimal addition of 1,2-diaminoethane (DAE). The theoretical design for the experiments are illustrated and further proved by the characterization results with different concentrations and reagents. On the other hand, generation of CdTe QDs was found even under room temperature by applying droplet quantity of DAE. This indicates that QDs can be synthesized with simply a bottle and no enormous additives required. The QDs were mixed into the epoxy matrix through solution casting method with cetyltrimethylammonium (CTA) capping for phase transfer. The acquired epoxy based nanocomposite exhibits good transparency, compatibility and fluorescence.

  6. The correlation of blue shift of photoluminescence and morphology of silicon nanoporous

    Energy Technology Data Exchange (ETDEWEB)

    Al-Jumaili, Batool E. B., E-mail: batooleneaze@gmail.com [Department of Physics, (UPM), Serdang, Selangor 43400 (Malaysia); Department of Physics, Anbar University (Iraq); Talib, Zainal A.; Josephine, L.Y.; Paiman, Suriati B.; Muh’d, Ibrahim B.; Mofdal, Manahil E. E. [Department of Physics, (UPM), Serdang, Selangor 43400 (Malaysia); Ahmed, Naser M.; Abdulateef, Sinan A. [School of Physics, USM, 11800 Penang (Malaysia); Al-Jumaily, Abdulmajeed H. J. [Department of Computer and Communication Systems Engineering, Universiti Putra Malaysia (UPM), Serdang, Selangor 43400 (Malaysia); Ramizy, Asmiet [Department of Physics, Anbar University (Iraq)

    2016-07-06

    Porous silicon with diameters ranging from 6.41 to 7.12 nm were synthesized via electrochemical etching by varied anodization current density in ethanoic solutions containing aqueous hydrofluoric acid up to 65 mA/cm{sup 2}.The luminescence properties of the nanoporous at room temperature were analyzed via photoluminescence spectroscopy. Photoluminescence PL spectra exhibit a broad emission band in the range of 360-700 nm photon energy. The PL spectrum has a blue shift in varied anodization current density; the blue shift incremented as the existing of anodization although the intensity decreased. The current blue shift is owning to alteration of silicon nanocrystal structure at the superficies. The superficial morphology of the PS layers consists of unified and orderly distribution of nanocrystalline Si structures, have high porosity around (93.75%) and high thickness 39.52 µm.

  7. Comparison of Cottonwood Dendrochronology and Optically Stimulated Luminescence Geochronometers Along a High Plains Meandering River, Powder River, Montana, USA

    Science.gov (United States)

    Hasse, T. R.; Schook, D. M.

    2017-12-01

    Geochronometers at centennial scales can aid our understanding of process rates in fluvial geomorphology. Plains cottonwood trees (Populus deltoides ssp. Monilifera) in the high plains of the United States are known to germinate on freshly created deposits such as point bars adjacent to rivers. As the trees mature they may be partially buried (up to a few meters) by additional flood deposits. Cottonwood age gives a minimum age estimate of the stratigraphic surface where the tree germinated and a maximum age estimate for overlying sediments, providing quantitative data on rates of river migration and sediment accumulation. Optically Stimulated Luminescence (OSL) of sand grains can be used to estimate the time since the sand grains were last exposed to sunlight, also giving a minimum age estimate of sediment burial. Both methods have disadvantages: Browsing, partial burial, and other damage to young cottonwoods can increase the time required for the tree to reach a height where it can be sampled with a tree corer, making the germination point a few years to a few decades older than the measured tree age; fluvial OSL samples can have inherited age (when the OSL age is older than the burial age) if the sediment was not completely bleached prior to burial. We collected OSL samples at 8 eroding banks of the Powder River Montana, and tree cores at breast height (±1.2 m) from cottonwood trees growing on the floodplain adjacent to the OSL sample locations. Using the Minimum Age Model (MAM) we found that OSL ages appear to be 500 to 1,000 years older than the adjacent cottonwood trees which range in age (at breast height) from 60 to 185 years. Three explanations for this apparent anomaly in ages are explored. Samples for OSL could be below a stratigraphic unconformity relative to the cottonwood germination elevation. Shallow samples for OSL could be affected by anthropogenic mixing of sediments due to plowing and leveling of hay fields. The OSL samples could have

  8. Highly luminescent N, S- Co-doped carbon dots and their direct use as mercury(II) sensor

    International Nuclear Information System (INIS)

    Wang, Yu; Kim, Sung-Hoon; Feng, Liang

    2015-01-01

    Heteroatom doping has been proven as an efficient way to improve the fluorescent efficiency of carbon dots. Co-doping with heteroatoms may introduce more active sites to carbon dots, which would broaden applications of CDs in sensing. In this work, highly luminescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized through a facile one-step microwave assisted method by using citric acid and rubeanic acid as carbon, nitrogen, and sulfur sources. The well-isolated NSCDs not only exhibit an enhanced fluorescent efficiency with a relatively high quantum yield up to 17.6%, but also show potential use as a multi-sensing platform based on their fluorescence “on-off-on” and color changing behaviors. The NSCDs can be directly used for the selective determination of mercury cations without any functionalization. The detection limit is approximately calculated as 0.18 μM and linear range is 0–20 μM. The sensing mechanism is proposed as coordination reaction induced by oligomers upon the carbon core. Furthermore, in the presence of cyanide anions, the fluorescence shows linear recovery associated with the concentration of cyanide, indicating its potential usage for the detection of cyanide ion. The optimized pH range for such fluorescence “on-off-on” sensing system is investigated as pH 6–8, suggesting potential applications in bio-sensing and imaging area. In addition, by adding hydrosulfide anion to NSCDs@Hg 2+ complex, a notable color change could be clearly observed due to the formation of fuscous HgS. In application, a handy test paper for direct and rapid detection of Hg 2+ is manufactured for the evaluation of usage of NSCDs in the real circumstance. - Highlights: • NSCDs were synthesized by using citric acid and rubeanic acid. • NSCDs exhibited an enhanced fluorescent efficiency with high QY up to 17.6%. • NSCDs presented good sensing performance to mercury ions. • NSCDs showed potential use as a multi-sensing platform

  9. Highly luminescent N, S- Co-doped carbon dots and their direct use as mercury(II) sensor

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu [Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China); Department of Advanced Organic Materials Science and Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Kim, Sung-Hoon, E-mail: shokim@knu.ac.kr [Department of Advanced Organic Materials Science and Engineering, Kyungpook National University, Daegu, 702-701 (Korea, Republic of); Feng, Liang, E-mail: fengl@dicp.ac.cn [Key Lab of Separation Science for Analytical Chemistry, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023 (China)

    2015-08-26

    Heteroatom doping has been proven as an efficient way to improve the fluorescent efficiency of carbon dots. Co-doping with heteroatoms may introduce more active sites to carbon dots, which would broaden applications of CDs in sensing. In this work, highly luminescent nitrogen and sulfur co-doped carbon dots (NSCDs) were synthesized through a facile one-step microwave assisted method by using citric acid and rubeanic acid as carbon, nitrogen, and sulfur sources. The well-isolated NSCDs not only exhibit an enhanced fluorescent efficiency with a relatively high quantum yield up to 17.6%, but also show potential use as a multi-sensing platform based on their fluorescence “on-off-on” and color changing behaviors. The NSCDs can be directly used for the selective determination of mercury cations without any functionalization. The detection limit is approximately calculated as 0.18 μM and linear range is 0–20 μM. The sensing mechanism is proposed as coordination reaction induced by oligomers upon the carbon core. Furthermore, in the presence of cyanide anions, the fluorescence shows linear recovery associated with the concentration of cyanide, indicating its potential usage for the detection of cyanide ion. The optimized pH range for such fluorescence “on-off-on” sensing system is investigated as pH 6–8, suggesting potential applications in bio-sensing and imaging area. In addition, by adding hydrosulfide anion to NSCDs@Hg{sup 2+} complex, a notable color change could be clearly observed due to the formation of fuscous HgS. In application, a handy test paper for direct and rapid detection of Hg{sup 2+} is manufactured for the evaluation of usage of NSCDs in the real circumstance. - Highlights: • NSCDs were synthesized by using citric acid and rubeanic acid. • NSCDs exhibited an enhanced fluorescent efficiency with high QY up to 17.6%. • NSCDs presented good sensing performance to mercury ions. • NSCDs showed potential use as a multi-sensing platform.

  10. Luminescent tracks of high-energy photoemitted electrons accelerated by plasmonic fields

    Directory of Open Access Journals (Sweden)

    Di Vece Marcel

    2015-12-01

    Full Text Available The emission of an electron from a metal nanostructure under illumination and its subsequent acceleration in a plasmonic field forms a platform to extend these phenomena to deposited nanoparticles, which can be studied by state-of-the-art confocal microscopy combined with femtosecond optical excitation. The emitted and accelerated electrons leave defect tracks in the immersion oil, which can be revealed by thermoluminescence. These photographic tracks are read out with the confocal microscope and have a maximum length of about 80 μm, which corresponds to a kinetic energy of about 100 keV. This energy is consistent with the energy provided by the intense laser pulse combined with plasmonic local field enhancement. The results are discussed within the context of the rescattering model by which electrons acquire more energy. The visualization of electron tracks originating from plasmonic field enhancement around a gold nanoparticle opens a new way to study with confocal microscopy both the plasmonic properties of metal nano objects as well as high energy electron interaction with matter.

  11. Pure Cs4PbBr6: Highly Luminescent Zero-Dimensional Perovskite Solids

    KAUST Repository

    Saidaminov, Makhsud I.

    2016-09-26

    So-called zero-dimensional perovskites, such as Cs4PbBr6, promise outstanding emissive properties. However, Cs4PbBr6 is mostly prepared by melting of precursors that usually leads to a coformation of undesired phases. Here, we report a simple low-temperature solution-processed synthesis of pure Cs4PbBr6 with remarkable emission properties. We found that pure Cs4PbBr6 in solid form exhibits a 45% photoluminescence quantum yield (PLQY), in contrast to its three-dimensional counterpart, CsPbBr3, which exhibits more than 2 orders of magnitude lower PLQY. Such a PLQY of Cs4PbBr6 is significantly higher than that of other solid forms of lower-dimensional metal halide perovskite derivatives and perovskite nanocrystals. We attribute this dramatic increase in PL to the high exciton binding energy, which we estimate to be ∼353 meV, likely induced by the unique Bergerhoff–Schmitz–Dumont-type crystal structure of Cs4PbBr6, in which metal-halide-comprised octahedra are spatially confined. Our findings bring this class of perovskite derivatives to the forefront of color-converting and light-emitting applications.

  12. High pressure study of viscosity effects on the luminescence of tetracyanobenzene EDA complexes

    Science.gov (United States)

    Thomas, Michele Moisio; Drickamer, H. G.

    1981-03-01

    High pressure fluorescence studies fron 0-10 kbar have been performed on electron donor-acceptor (EDA) complexes of s-tetracyanobenzene (TCNB) with a series of aromatic hydrocarbons. Four solvents were used, 2,2,4,4,6,8,8 heptamethylnonane (HMN), methylcyclohexane (MCH), 2,6,10,14 tetramethylpentadecane (TMPD), and a mixture of MCH and HMN. A viscosity range from 0.006 to 10 000 poise was covered at constant temperature. As pressure (viscosity) increased the fluorescence spectrum shifted from one dominated by emission from the equilibrium (EQ) excited singlet state to one dominated by Franck-Condon (FC) singlet emission. Lifetime measurements for the complexes of o-xylene and p-xylene with TCNB as well as one mesitylene complex yielded the two radiative rates (kEQ and kFC) as well as the rate of internal conversion from FC to the EQ excited state to (kIC). The results are discussed in terms of the rate of relaxation of the solvent compared with the rate kFC. It was found that kIC correlated very well with the solvent viscosity.

  13. A preliminary research of characteristic of selected frequency luminescence for debris flow in Jiangjiagou valley

    International Nuclear Information System (INIS)

    Liu Zhaowen; Wei Mingjian; Li Dongxu; Pan Baolin; Ge Yonggang

    2009-01-01

    Four debris flow samples were separated from Nidepin, Duozhao and Dawazigou valleys in Jiangjiagou valley area, Yunnan province. They were measured with BG2003 luminescence spectrograph. The characteristic spectra of the selected frequency luminescence of samples from the different locations were obtained. The wave length of emission photons from samples of Dawazigou valley and Jiangjia valley are 300, 310, 320, 400 and 460 nm when it was using blue light (488)nm excited. When the green light (532 nm) has been used to excited, the wave length of emission photons from samples of Dawazigou valley and Duozhao valley are similar high at 310 and 320 nm. Furthermore, using the green light excited the samples from desert sand at the same lab condition; the number of absorbed photons of samples from desert sand is much higher than from debris flow. (authors)

  14. Single photon detection and signal analysis for high sensitivity dosimetry based on optically stimulated luminescence with beryllium oxide

    Science.gov (United States)

    Radtke, J.; Sponner, J.; Jakobi, C.; Schneider, J.; Sommer, M.; Teichmann, T.; Ullrich, W.; Henniger, J.; Kormoll, T.

    2018-01-01

    Single photon detection applied to optically stimulated luminescence (OSL) dosimetry is a promising approach due to the low level of luminescence light and the known statistical behavior of single photon events. Time resolved detection allows to apply a variety of different and independent data analysis methods. Furthermore, using amplitude modulated stimulation impresses time- and frequency information into the OSL light and therefore allows for additional means of analysis. Considering the impressed frequency information, data analysis by using Fourier transform algorithms or other digital filters can be used for separating the OSL signal from unwanted light or events generated by other phenomena. This potentially lowers the detection limits of low dose measurements and might improve the reproducibility and stability of obtained data. In this work, an OSL system based on a single photon detector, a fast and accurate stimulation unit and an FPGA is presented. Different analysis algorithms which are applied to the single photon data are discussed.

  15. Forensic Analysis of Blue Ball point Pen Inks on Questioned Documents by High Performance Thin Layer Chromatography Technique (HPTLC)

    International Nuclear Information System (INIS)

    Lee, L.C.; Siti Mariam Nunurung; Abdul Aziz Ishak

    2014-01-01

    Nowadays, crimes related to forged documents are increasing. Any erasure, addition or modification in the document content always involves the use of writing instrument such as ball point pens. Hence, there is an evident need to develop a fast and accurate ink analysis protocol to solve this problem. This study is aimed to determine the discrimination power of high performance thin layer chromatography (HPTLC) technique for analyzing a set of blue ball point pen inks. Ink samples deposited on paper were extracted using methanol and separated via a solvent mixture of ethyl acetate, methanol and distilled water (70: 35: 30, v/ v/ v). In this method, the discrimination power of 89.40 % was achieved, which confirm that the proposed method was able to differentiate a significant number of pen-pair samples. In addition, composition of blue pen inks was found to be homogeneous (RSD < 2.5 %) and the proposed method showed good repeatability and reproducibility (RSD < 3. 0%). As a conclusion, HPTLC is an effective tool to separate blue ball point pen inks. (author)

  16. Investigation into scanning tunnelling luminescence microscopy

    International Nuclear Information System (INIS)

    Manson-Smith, S.K.

    2001-01-01

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

  17. Highly sensitive sorption-luminescence determination of trace europium with preconcentration on silica chemically modified with iminodiacetic acid

    International Nuclear Information System (INIS)

    Voronina, R.D.; Zorov, N.B.

    2007-01-01

    Features of a sorption-luminescence method for the determination of trace europium were studied. The method includes the preliminary sorption of europium at pH 7.1 from solutions with silica chemically modified with iminodiacetic acid, the subsequent treatment of the sorbent with 2-thenoyltrifluoroacetone at pH 8.0, and the measurement of the intensity of luminescence of the surface three-component europium complex at 613 nm. The effect of moisture as the quencher of luminescence of the surface europium complex was studied, and techniques for its removal were proposed. Sorption in the static mode provides the detection limit of europium of 7 x 10 -5 g/ml. The calibration plot is linear in the range of two orders of magnitude of europium concentration in solutions. The relative standard deviation in the determination of 1.5 x 10 -2 μg/ml europium is 5%. In the dynamic mode of sorption from 1000 ml of an analyzed solution with the use of sorption-desorption, the detection limit of europium of 8 x 10 -7 μg/ml was attained [ru

  18. A highly selective and non-reaction based chemosensor for the detection of Hg2+ ions using a luminescent iridium(III complex.

    Directory of Open Access Journals (Sweden)

    Daniel Shiu-Hin Chan

    Full Text Available We report herein a novel luminescent iridium(III complex with two hydrophobic carbon chains as a non-reaction based chemosensor for the detection of Hg(2+ ions in aqueous solution (<0.002% of organic solvent attributed to the probe solution. Upon the addition of Hg(2+ ions, the emission intensity of the complex was significantly enhanced and this change could be monitored by the naked eye under UV irradiation. The iridium(III complex shows high specificity for Hg(2+ ions over eighteen other cations. The system is capable of detecting micromolar levels of Hg(2+ ions, which is within the range of many chemical systems.

  19. Detection of food irradiation with luminescence methods

    International Nuclear Information System (INIS)

    Anderle, H.

    1997-06-01

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

  20. Luminescence and energy transfer

    Energy Technology Data Exchange (ETDEWEB)

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

    1980-01-01

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

  1. Formation of highly toxic hydrogen cyanide upon ruby laser irradiation of the tattoo pigment phthalocyanine blue

    Science.gov (United States)

    Schreiver, Ines; Hutzler, Christoph; Laux, Peter; Berlien, Hans-Peter; Luch, Andreas

    2015-08-01

    Since laser treatment of tattoos is the favored method for the removing of no longer wanted permanent skin paintings, analytical, biokinetics and toxicological data on the fragmentation pattern of commonly used pigments are urgently required for health safety reasons. Applying dynamic headspace—gas chromatography with mass spectrometric detection (DHS—GC/MS) and comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GCxGC—ToF-MS), we identified 1,2-benzene dicarbonitrile, benzonitrile, benzene, and the poisonous gas hydrogen cyanide (HCN) as main fragmentation products emerging dose-dependently upon ruby laser irradiation of the popular blue pigment copper phthalocyanine in suspension. Skin cell viability was found to be significantly compromised at cyanide levels of ≥1 mM liberated during ruby laser irradiation of >1.5 mg/ml phthalocyanine blue. Further, for the first time we introduce pyrolysis-GC/MS as method suitable to simulate pigment fragmentation that may occur spontaneously or during laser removal of organic pigments in the living skin of tattooed people. According to the literature such regular tattoos hold up to 9 mg pigment/cm2 skin.

  2. Improved methylene blue two-phase titration method for determining cationic surfactant concentration in high-salinity brine.

    Science.gov (United States)

    Cui, Leyu; Puerto, Maura; López-Salinas, José L; Biswal, Sibani L; Hirasaki, George J

    2014-11-18

    The methylene blue (MB) two-phase titration method is a rapid and efficient method for determining the concentrations of anionic surfactants. The point at which the aqueous and chloroform phases appear equally blue is called Epton's end point. However, many inorganic anions, e.g., Cl(-), NO3(-), Br(-), and I(-), can form ion pairs with MB(+) and interfere with Epton's end point, resulting in the failure of the MB two-phase titration in high-salinity brine. Here we present a method to extend the MB two-phase titration method for determining the concentration of various cationic surfactants in both deionized water and high-salinity brine (22% total dissolved solid). A colorless end point, at which the blue color is completely transferred from the aqueous phase to the chloroform phase, is proposed as titration end point. Light absorbance at the characteristic wavelength of MB is measured using a spectrophotometer. When the absorbance falls below a threshold value of 0.04, the aqueous phase is considered colorless, indicating that the end point has been reached. By using this improved method, the overall error for the titration of a permanent cationic surfactant, e.g., dodecyltrimethylammonium bromide, in deionized (DI) water and high-salinity brine is 1.274% and 1.322% with limits of detection (LOD) of 0.149 and 0.215 mM, respectively. Compared to the traditional acid-base titration method, the error of this improved method for a switchable cationic surfactant, e.g., tertiary amine surfactant (Ethomeen C12), is 2.22% in DI water and 0.106% with LOD of 0.369 and 0.439 mM, respectively.

  3. Sintering process of Eu doped luminescent glass prepared from porous glass

    International Nuclear Information System (INIS)

    Akai, T; Murakami, M; Yamashita, M; Okajima, T; Umesaki, N

    2011-01-01

    Eu doped high silica glass prepared by sintering porous glass exhibits blue luminescence with high quantum efficiency. In this work, we studied effects of sintering temperature on valance state of europium ion. To investigate a change of valance state of Eu, X-ray absorption near edge structure (XANES) spectroscopy measurements were carried out. Intensity of blue emission at around 430nm drastically increases when the sintering temperature is above 1000 deg. C. From XANES spectra, it is found that almost all the Eu exist as Eu 3+ in a samples sintered below 900 deg. C, while more than 70% of Eu exist as Eu 2+ in the sample sintered at 1050 deg. C and 1100 deg. C. The drastic change of oxidation state of europium ion between 900 and 1050 deg. C is discussed in relation to the structural change probed by infrared (IR) spectroscopy.

  4. Highly Luminescent 2D-Type Slab Crystals Based on a Molecular Charge-Transfer Complex as Promising Organic Light-Emitting Transistor Materials.

    Science.gov (United States)

    Park, Sang Kyu; Kim, Jin Hong; Ohto, Tatsuhiko; Yamada, Ryo; Jones, Andrew O F; Whang, Dong Ryeol; Cho, Illhun; Oh, Sangyoon; Hong, Seung Hwa; Kwon, Ji Eon; Kim, Jong H; Olivier, Yoann; Fischer, Roland; Resel, Roland; Gierschner, Johannes; Tada, Hirokazu; Park, Soo Young

    2017-09-01

    A new 2:1 donor (D):acceptor (A) mixed-stacked charge-transfer (CT) cocrystal comprising isometrically structured dicyanodistyrylbenzene-based D and A molecules is designed and synthesized. Uniform 2D-type morphology is manifested by the exquisite interplay of intermolecular interactions. In addition to its appealing structural features, unique optoelectronic properties are unveiled. Exceptionally high photoluminescence quantum yield (Φ F ≈ 60%) is realized by non-negligible oscillator strength of the S 1 transition, and rigidified 2D-type structure. Moreover, this luminescent 2D-type CT crystal exhibits balanced ambipolar transport (µ h and µ e of ≈10 -4 cm 2 V -1 s -1 ). As a consequence of such unique optoelectronic characteristics, the first CT electroluminescence is demonstrated in a single active-layered organic light-emitting transistor (OLET) device. The external quantum efficiency of this OLET is as high as 1.5% to suggest a promising potential of luminescent mixed-stacked CT cocrystals in OLET applications. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  5. Highly sensitive and selective cartap nanosensor based on luminescence resonance energy transfer between NaYF4:Yb,Ho nanocrystals and gold nanoparticles.

    Science.gov (United States)

    Wang, Zhijiang; Wu, Lina; Shen, Baozhong; Jiang, Zhaohua

    2013-09-30

    Fluorescent detection is an attractive method for the detection of toxic chemicals. However, most chemosensors that are currently utilized in fluorescent detection are based on organic dyes or quantum dots, which suffer from instability, high background noise and interference from organic impurities in solution, which can also be excited by UV radiation. In the present research, we developed a novel NaYF4:Yb,Ho/Au nanocomposite-based chemosensor with high sensitivity (10 ppb) and selectivity over competing analytes for the detection of the insecticide cartap. This nanosensor is excited with a 970-nm laser instead of UV radiation to give an emission peak at 541 nm. In the presence of cartap, the nanocomposites aggregate, resulting in enhanced luminescence resonance energy transfer between the NaYF4:Yb,Ho nanocrystals and the gold nanoparticles, which decreases the emission intensity at 541 nm. The relative luminescence intensity at 541 nm has a linear relationship with the concentration of cartap in the solution. Based on this behavior, the developed nanosensor successfully detected cartap in farm produce and water samples with satisfactory results. Copyright © 2013 Elsevier B.V. All rights reserved.

  6. Metal-Organic Framework Nanosheets for Fast-Response and Highly Sensitive Luminescent Sensing of Fe3+

    DEFF Research Database (Denmark)

    Xu, Hui; Iversen, Bo Brummerstedt

    of graphene, Since the discovery of graphene, series of two-dimensional (2-D) nanosheets materials such as metal oxides, metal hydroxides, transition metal chalcogenides (TMDs), boron nitride (BN) and black phosphorus have been of great interests, and have been extensively investigated for applications...... in electronics, lithium-ion batteries, catalysis and mechanical properties, etc. 2-D MOF nanosheets materials, as a new member of the 2-D nanomaterials family, are still at the very early stage. However, to the best of our knowledge, the 2-D MOF nanosheets materials for luminescent sensing have been rarely...

  7. Luminescent beam stop

    Energy Technology Data Exchange (ETDEWEB)

    Bryant, Diane; Morton, Simon A.

    2017-10-25

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

  8. Luminescence detection of shellfish

    International Nuclear Information System (INIS)

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

    1996-01-01

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

  9. Recent developments in luminescent solar concentrators

    Science.gov (United States)

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

    2014-10-01

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

  10. Time-resolved luminescence from feldspars: New insight into fading

    DEFF Research Database (Denmark)

    Tsukamoto, S.; Denby, P.M.; Murray, A.S.

    2006-01-01

    Time-resolved infrared optically stimulated luminescence (IR-OSL) signals of K- and Na-feldspar samples extracted from sediments were measured in UV, blue and red detection windows, using a fast photon counter and pulsed IR stimulation (lambda = 875 nm). We observe that the relative contribution ...

  11. Synthesis and luminescence in sol–gel auto-combustion ...

    Indian Academy of Sciences (India)

    2017-11-14

    Nov 14, 2017 ... Eu-doped CaSnO3 showed broad blue emission centred about 434 nm, a ... symmetry [5]. Recently, luminescence properties of rare-earth-cation- ... able attention due to their abundant emission colours based on their 4f–4f or ...

  12. [Structure and luminescence properties of Ga2O3 : Cr3+ by Al doping].

    Science.gov (United States)

    Wang, Xian-Sheng; Wan, Min-Hua; Wang, Yin-Hai; Zhao, Hui; Hu, Zheng-Fa; Li, Hai-Ling

    2013-11-01

    The Al doping gallate phosphor (Ga(1-x)Al(x))2O3 : Cr3+ (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5) was synthesized by a high temperature solid-state reaction method. The X-ray diffractions show that the phase of the phosphors remains to be Ga2 O3 structure with increase in the contents of Al3+ ion. Beside, the fact that the X-ray diffraction peak shifts towards big angles with increasing Al3+ ions content shows that Al3+ ions entered the Ga2 O3 lattice. The peaks of the excitation spectra located at 258, 300, 410 and 550 nm are attributed to the band to band transition of the matrix, charge transfer band transition, and 4A2 --> 4T1 and 4A2 --> 4T2 transition of Cr3+ ions, respectively. Those excitation spectrum peak positions show different degrees of blue shift with the increase in the Al3+ ions content. The blue shift of the first two peaks are due to the band gap energy of substrate and the electronegativity between Cr3+ ions and ligands increasing, respectively. The blue shift of the energy level transition of Cr3+ ion is attributed to crystal field strength increasing. The Cr3+ ion luminescence changes from a broadband emission to a narrow-band emission with Al3+ doping, because the emission of Cr3+ ion changed from 4 T2 --> 4A2 to 2E --> 4A2 transition with the crystal field change after Al3+ ions doping. The Al3+ ions doping improved the long afterglow luminescence properties of samples, and the sample showed a longer visible near infrared when Al3+ ions content reaches 0.5. The thermoluminescence curve shows the sample with suitable trap energy level, and this is also the cause of the long afterglow luminescence materials.

  13. Luminescence and Luminescence Quenching of K2Bi(PO4)(MoO4):Eu3+ Phosphors with Efficiencies Close to Unity.

    Science.gov (United States)

    Grigorjevaite, Julija; Katelnikovas, Arturas

    2016-11-23

    A very good light emitting diode (LED) phosphor must have strong absorption, high quantum efficiency, high color purity, and high quenching temperature. Our synthesized K 2 Bi(PO 4 )(MoO 4 ):Eu 3+ phosphors possess all of the mentioned properties. The excitation of these phosphors with the near-UV or blue radiation results in a bright red luminescence dominated by the 5 D 0 → 7 F 2 transition at ∼615 nm. Color coordinates are very stable when changing Eu 3+ concentration or temperature in the range of 77-500 K. Furthermore, samples doped with 50% and 75% Eu 3+ showed quantum efficiencies close to 100% which is a huge benefit for practical application. Temperature dependent luminescence measurements showed that phosphor performance increases with increasing Eu 3+ concentration. K 2 Eu(PO 4 )(MoO 4 ) sample at 400 K lost only 20% of the initial intensity at 77 K and would lose half of the intensity only at 578 K. Besides, the ceramic disks with thicknesses of 0.33 and 0.89 mm were prepared from K 2 Eu(PO 4 )(MoO 4 ) powder, and it turned out that they efficiently converted the radiation of 375 nm LED to the red light. The conversion of 400 nm LED radiation to the red light was not complete; thus, the light sources with various tints of purple color were obtained. The combination of ceramic disks with 455 nm LED yielded the light sources with tints of blue color due to the low absorption of ceramic disk in this spectral range. In addition, these phosphors possess a very unique emission spectra; thus, they could also be applied in luminescent security pigments.

  14. Controlled fabrication of luminescent and magnetic nanocomposites

    Science.gov (United States)

    Ma, Yingxin; Zhong, Yucheng; Fan, Jing; Huang, Weiren

    2018-03-01

    Luminescent and magnetic multifunctional nanocomposite is in high demand and widely used in many scales, such as drug delivery, bioseparation, chemical/biosensors, and so on. Although lots of strategies have been successfully developed for the demand of multifunctional nanocomposites, it is not easy to prepare multifunctional nanocomposites by using a simple method, and satisfy all kinds of demands simultaneously. In this work, via a facile and versatile method, luminescent nanocrystals and magnetic nanoparticles were successfully synthesized through self-assembly under vigorous stirring and ultrasonic treatment. These multifunctional nanocomposites are not only water stable but also find wide application such as magnetic separation and concentration with a series of moderate speed, multicolor fluorescence at different emission wavelength, high efficiency of the excitation and emission, and so on. By changing different kinds of luminescent nanocrystals and controlling the amount of luminescent and magnetic nanoparticles, a train of multifunctional nanocomposites was successfully fabricated via a versatile and robust method.

  15. Structural, luminescent and thermal properties of blue SrAl{sub 2}O{sub 4}:Eu{sup 2+}, Dy{sup 3+} phosphor filled low-density polyethylene composites

    Energy Technology Data Exchange (ETDEWEB)

    Bem, D.B. [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Luyt, A.S. [Department of Chemistry, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Dejene, F.B., E-mail: dejenebf@qwa.ufs.ac.z [Department of Physics, University of the Free State (Qwaqwa Campus), Private Bag X13, Phuthaditjhaba 9866 (South Africa); Botha, J.R. [Department of Physics, Nelson Mandela Metropolitan University, P.O. Box 70000, Port Elizabeth 6031 (South Africa); Swart, H.C. [Department of Physics, University of the Free State, P.O. Box 339, Bloemfontein 9300 (South Africa)

    2009-12-01

    The performance of nanophase luminophors is usually compromised by environmentally induced degradation. In this study, composites of low density polyethylene (LDPE) with various concentrations of the blue-emitting europium and dysprosium co-doped strontium aluminate (SrAl{sub 2}O{sub 4}:Eu{sup 2+},Dy{sup 3+}) phosphor were investigated. The blue long-lasting phosphorescence of the composites was observed in the dark after removal of the excitation light. X-ray diffraction analysis revealed the presence of the SrAl{sub 2}O{sub 4} phase in the composites. PL spectra of the composites have two sets of peaks, major broad bands peaking at about 4855 A and minor ones at wavelengths between 4115 and 4175 A, attributed to the 4f-5d transition of Eu{sup 2+}. DSC and TGA results show that the introduction of the phosphor in LDPE matrix caused a slight reduction in the crystallinity of LDPE but a significant increase in the stability of the composites.

  16. Effect of high current density to defect generation of blue LED and its characterization with transmission electron microscope

    Science.gov (United States)

    Gunawan, R.; Sugiarti, E.; Isnaeni; Purawiardi, R. I.; Widodo, H.; Muslimin, A. N.; Yuliasari; Ronaldus, C. E.; Prastomo, N.; Hastuty, S.

    2018-03-01

    The optical, electrical and structural characteristics of InGaN-based blue light-emitting diodes (LEDs) were investigated to identify the degradation of LED before and after current injection. The sample was injected by high current of 200 A/cm2 for 5 and 20 minutes. It was observed that injection of current shifts light intensity and wavelength characteristics that indicated defect generation. Transmission Electron Microscopy (TEM) characterization was carried out in order to clarify the structure degradation caused by defect in active layer which consisted of 14 quantum well with thickness of about 5 nm and confined with barrier layer with thickness of about 12 nm. TEM results showed pre-existing defect in LED before injection with high current. Furthermore, discontinue and edge defect was found in dark spot region of LED after injection with high current.

  17. Growth of filamentous blue-green algae at high temperatures: a source of biomass for renewable fuels

    Energy Technology Data Exchange (ETDEWEB)

    Timourian, H.; Ward, R.L.; Jeffries, T.W.

    1977-08-17

    The growth of filamentous blue-green algae (FBGA) at high temperatures in outdoor, shallow solar ponds is being investigated. The temperature of the 60-m/sup 2/ ponds can be controlled to an average temperature of 45/sup 0/C. The growth of FBGA at high temperatures offers an opportunity, not presently available from outdoor algal ponds or energy farms, to obtain large amounts of biomass. Growth of algae at high temperatures results in higher yields because of increased growth rate, the higher light intensity that can be used before saturating the photosynthetic process, easier maintenance of selected FBGA strains, and fewer predators to decimate culture. Additional advantages of growing FBGA as a source of biomass include: bypassing the limitations of nutrient sources, because FBGA fix their own nitrogen and require only CO/sub 2/ when inorganic nutrients are recycled; toleration of higher salinity and metal ion concentrations; and easier and less expensive harvesting procedures.

  18. Electron beam induced coloration and luminescence in layered structure of WO3 thin films grown by pulsed dc magnetron sputtering

    International Nuclear Information System (INIS)

    Karuppasamy, A.; Subrahmanyam, A.

    2007-01-01

    Tungsten oxide thin films have been deposited by pulsed dc magnetron sputtering of tungsten in argon and oxygen atmosphere. The as-deposited WO 3 film is amorphous, highly transparent, and shows a layered structure along the edges. In addition, the optical properties of the as-deposited film show a steplike behavior of extinction coefficient. However, the electron beam irradiation (3.0 keV) of the as-deposited films results in crystallization, coloration (deep blue), and luminescence (intense red emission). The above changes in physical properties are attributed to the extraction of oxygen atoms from the sample and the structural modifications induced by electron bombardment. The present method of coloration and luminescence has a potential for fabricating high-density optical data storage device

  19. Bright white upconversion luminescence from Er3+/Tm3+/Yb3+-doped titanate-based glasses prepared by aerodynamic levitation method

    Science.gov (United States)

    Zhang, Minghui; Yu, Jianding; Jiang, Wan; Liu, Yan; Ai, Fei; Wen, Haiqin; Jiang, Meng; Yu, Huimei; Pan, Xiuhong; Tang, Meibo; Gai, Lijun

    2017-10-01

    Aerodynamic levitation method was employed to prepare Er3+/Tm3+/Yb3+-doped titanate-based glasses. DTA results show that the glass performs high thermal stability with the glass transition temperature of 799 °C. The interaction among rare earth ions has been discussed by adjusting the relative concentration. Er3+ ions can quench the upconversion luminescence of Tm3+ ions. Tm3+ ions play a strong role in quenching the emissions of Er3+ and Tm3+ when the content of Tm3+ ions is greater than or equal 0.05. From the view of the ratio of red emission to green emission, Tm3+ ions can improve the red emission of Er3+ ions to some extent in contrast with the green emissions of Er3+ ions. 980 nm incident laser can be efficiently absorbed by Yb3+ ions. The relative intensity of red, green, and blue upconversion luminescence has been tuned to obtain white light. The composition with white upconversion luminescence of the color coordinate (0.291, 0.3292) has been found. Moreover, white upconversion luminescence mechanism is a two-photon process of ET, ESA, and cooperative sensitization. Rare earth ions doped titanate-based glasses with bright upconversion luminescence perform potential applications in color display, back light, et al.

  20. High innate attractiveness to black targets in the blue blowfly, Calliphora vomitoria (L.) (Diptera: Calliphoridae).

    Science.gov (United States)

    Benelli, Giovanni; Otranto, Domenico; Caselli, Alice; Romano, Donato; Remorini, Damiano; Di Giuseppe, Graziano; Stefanini, Cesare; Mele, Marcello; Canale, Angelo

    2018-06-01

    Calliphora vomitoria is a myiasis-causing fly in many animal species including humans. The control of blowflies is still anchored on the use of chemicals. However, mass trapping and lure-and-kill techniques represent a promising alternative to pesticides. Visual and olfactory cues are the main stimuli routing the fly's landing behavior. Notably, color attractiveness has been barely explored in flies of medical and veterinary importance, with special reference to blowflies. In this study, we investigated the innate color preferences in C. vomitoria adults, testing binary combinations of painted targets under laboratory conditions. The identity of tested species C. vomitoria was confirmed by DNA sequencing (18S and cox1 genes). C. vomitoria flies showed a significant preference for black colored targets in all tested binary color combinations, after 5, 15, 30 and 60 min of exposure. Black targets were significantly preferred over blue, red, yellow and white ones. Spectral characteristics of all tested color combinations were quantified and the innate attraction of blowflies towards black targets was discussed in relation to their behavioral ecology. To the best of our knowledge, this is the first report on innate color preferences in the Calliphora genus. Our findings can be useful to develop new, cheap and reliable monitoring traps as well as "lure and kill" tools to control blowfly pests. Copyright © 2018 Elsevier B.V. All rights reserved.

  1. World without borders-genetic population structure of a highly migratory marine predator, the blue shark (Prionace glauca).

    Science.gov (United States)

    Veríssimo, Ana; Sampaio, Íris; McDowell, Jan R; Alexandrino, Paulo; Mucientes, Gonzalo; Queiroz, Nuno; da Silva, Charlene; Jones, Catherine S; Noble, Leslie R

    2017-07-01

    Highly migratory, cosmopolitan oceanic sharks often exhibit complex movement patterns influenced by ontogeny, reproduction, and feeding. These elusive species are particularly challenging to population genetic studies, as representative samples suitable for inferring genetic structure are difficult to obtain. Our study provides insights into the genetic population structure one of the most abundant and wide-ranging oceanic shark species, the blue shark Prionace glauca, by sampling the least mobile component of the populations, i.e., young-of-year and small juveniles (<2 year; N  = 348 individuals), at three reported nursery areas, namely, western Iberia, Azores, and South Africa. Samples were collected in two different time periods (2002-2008 and 2012-2015) and were screened at 12 nuclear microsatellites and at a 899-bp fragment of the mitochondrial control region. Our results show temporally stable genetic homogeneity among the three Atlantic nurseries at both nuclear and mitochondrial markers, suggesting basin-wide panmixia. In addition, comparison of mtDNA CR sequences from Atlantic and Indo-Pacific locations also indicated genetic homogeneity and unrestricted female-mediated gene flow between ocean basins. These results are discussed in light of the species' life history and ecology, but suggest that blue shark populations may be connected by gene flow at the global scale. The implications of the present findings to the management of this important fisheries resource are also discussed.

  2. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa.

    Directory of Open Access Journals (Sweden)

    Theoharis eOuzounis

    2015-02-01

    Full Text Available To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. ’Batavia’ (green and cv. ‘Lollo Rossa’ (red] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T lamps yielding 90 (±10 µmol m-2 s-1 for up to 20 hr, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED light treatments were Control (no blue addition, 1B 06-08 (Blue light at 45 µmol m-2 s-1 from 06:00 to 08:00, 1B 21-08 (Blue light at 45 µmol m-2 s-1 from 21:00 to 08:00, 2B 17-19 (Blue at 80 µmol m-2 s-1 from 17:00 to 19:00, and (1B 17-19 Blue at 45 µmol m-2 s-1from 17:00 to 19:00. Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  3. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa.

    Science.gov (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-01-01

    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. "Batavia" (green) and cv. "Lollo Rossa" (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m(-2) s(-1) for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m(-2) s(-1) from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m(-2) s(-1) from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m(-2) s(-1) from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m(-2) s(-1) from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent.

  4. Predawn and high intensity application of supplemental blue light decreases the quantum yield of PSII and enhances the amount of phenolic acids, flavonoids, and pigments in Lactuca sativa

    Science.gov (United States)

    Ouzounis, Theoharis; Razi Parjikolaei, Behnaz; Fretté, Xavier; Rosenqvist, Eva; Ottosen, Carl-Otto

    2015-01-01

    To evaluate the effect of blue light intensity and timing, two cultivars of lettuce [Lactuca sativa cv. “Batavia” (green) and cv. “Lollo Rossa” (red)] were grown in a greenhouse compartment in late winter under natural light and supplemental high pressure sodium (SON-T) lamps yielding 90 (±10) μmol m−2 s−1 for up to 20 h, but never between 17:00 and 21:00. The temperature in the greenhouse compartments was 22/11°C day/night, respectively. The five light-emitting diode (LED) light treatments were Control (no blue addition), 1B 06-08 (Blue light at 45 μmol m−2 s−1 from 06:00 to 08:00), 1B 21-08 (Blue light at 45 μmol m−2 s−1 from 21:00 to 08:00), 2B 17-19 (Blue at 80 μmol m−2 s−1 from 17:00 to 19:00), and 1B 17-19 (Blue at 45 μmol m−2 s−1 from 17:00 to 19:00). Total fresh and dry weight was not affected with additional blue light; however, plants treated with additional blue light were more compact. The stomatal conductance in the green lettuce cultivar was higher for all treatments with blue light compared to the Control. Photosynthetic yields measured with chlorophyll fluorescence showed different response between the cultivars; in red lettuce, the quantum yield of PSII decreased and the yield of non-photochemical quenching increased with increasing blue light, whereas in green lettuce no difference was observed. Quantification of secondary metabolites showed that all four treatments with additional blue light had higher amount of pigments, phenolic acids, and flavonoids compared to the Control. The effect was more prominent in red lettuce, highlighting that the results vary among treatments and compounds. Our results indicate that not only high light level triggers photoprotective heat dissipation in the plant, but also the specific spectral composition of the light itself at low intensities. However, these plant responses to light are cultivar dependent. PMID:25767473

  5. Highly luminescent core-shell InP/ZnX (X = S, Se) quantum dots prepared via a phosphine synthetic route.

    Science.gov (United States)

    Mordvinova, Natalia; Vinokurov, Alexander; Kuznetsova, Tatiana; Lebedev, Oleg I; Dorofeev, Sergey

    2017-01-24

    Here we report a simple method for the creation of highly luminescent core-shell InP/ZnX (X = S, Se) quantum dots (QDs) on the basis of a phosphine synthetic route. In this method a Zn precursor was added to the reaction mixture at the beginning of the synthesis to form an In(Zn)P alloy structure, which promoted the formation of a ZnX shell. Core-shell InP/ZnX QDs exhibit highly intensive emission with a quantum yield over 50%. The proposed method is primarily important for practical applications. Advantages of this method compared to the widely used SILAR technique are discussed. We further demonstrate that the SILAR approach consisting of consequent addition of Zn and chalcogen precursors to pre-prepared non-doped InP colloidal nanoparticles is not quite suitable for shell growth without the addition of special activator agents or the use of very reactive precursors.

  6. Combinatorial search for green and blue phosphors of high thermal stabilities under UV excitation based on the K(Sr1-x-y)PO4:Tb3+ xEu2+y system.

    Science.gov (United States)

    Chan, Ting-Shan; Liu, Yao-Min; Liu, Ru-Shi

    2008-01-01

    The present investigation aims at the synthesis of KSr 1-x-y PO 4:Tb(3+) x Eu(2+) y phosphors using the combinatorial chemistry method. We have developed square-type arrays consisting of 121 compositions to investigate the optimum composition and luminescence properties of KSrPO 4 host matrix under 365 nm ultraviolet (UV) light. The optimized compositions of phosphors were found to be KSr 0.93PO 4:Tb(3+) 0.07 (green) and KSr 0.995PO 4:Eu(2+) 0.005 (blue). These phosphors showed good thermal luminescence stability better than commercially available YAG:Ce at temperature above 200 degrees C. The result indicates that the KSr 1-x-y PO 4:Tb(3+) x Eu (2+)y can be potentially useful as a UV radiation-converting phosphor for light-emitting diodes.

  7. Red, green, and blue lanthanum phosphate phosphors obtained via surfactant-controlled hydrothermal synthesis

    International Nuclear Information System (INIS)

    Sousa Filho, Paulo C. de; Serra, Osvaldo A.

    2009-01-01

    A new solution route for the obtainment of highly pure luminescent rare-earth orthophosphates in hydrothermal conditions was developed. By starting from soluble precursors (lanthanide tripolyphosphato complexes, i.e. with P 3 O 10 5- as a complexing agent and as an orthophosphate source) and by applying surfactants in a water/toluene medium, the precipitations are confined to reverse micelle structures, thus yielding nanosized and homogeneous orthophosphates. The method was employed to obtain lanthanide-activated lanthanum phosphates, which can be applied as red (LaPO 4 :Eu 3+ ), green (LaPO 4 :Ce 3+ ,Tb 3+ ) and blue (LaPO 4 :Tm 3+ ) phosphors. The produced materials were analyzed by powder X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and luminescence spectroscopy (emission, excitation, lifetimes and chromaticity coordinates).

  8. Nature and mechanism of blue glow of corundum crystals; new point of view

    International Nuclear Information System (INIS)

    Bessonova, T.S.; Zabara, A.S.

    1987-01-01

    The photoluminescence and radioluminescence spectra were investigated for corrundum crystals grown by Verneil method with following thermal treatment in different conditions: 1) annealing in oxygen 8p=10 5 Pa, T=1770 K, t=5x10 5 s); 2) vacuum annealing (p=10 -3 Pa, T=2220 K, t=10 5 s); 3) annelaing in high reducing atmosphere. Two kinds of luminescence processes is shown to exist at 415-420 nm. Blue glow with δ ∼ 55 nm (band halfwidth) is due to anion vacancies while glow with δ ∼ 100 nm is caused by titanium ions of valancy 4. mechanisms of mentioned kinds of luminescence and their distinctive features presented. New model of electron transitions in Al 2 O 3 -lattice including anion vacancie for different excitation means is proposed

  9. Luminescence properties of a nanoporous freshwater diatom.

    Science.gov (United States)

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

    2012-01-01

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

  10. Electrostatic probes in luminescent discharges

    International Nuclear Information System (INIS)

    Cunha Raposo, C. da.

    1980-01-01

    A system to produce luminescent type plasma by continuos discharge and ionization by high frequency was constructed. The ionization was done in the air and in the argon under pressures from 3 to 10 mmHg. The parameters of a non magnetized collisional plasma and the parameters of a magnetized plasma such as, density, eletron temperature and potential, using a Langmuir probe with plane geometry, were determined. (M.C.K.) [pt

  11. Evolution of blue-flowered species of genus Linum based on high-throughput sequencing of ribosomal RNA genes.

    Science.gov (United States)

    Bolsheva, Nadezhda L; Melnikova, Nataliya V; Kirov, Ilya V; Speranskaya, Anna S; Krinitsina, Anastasia A; Dmitriev, Alexey A; Belenikin, Maxim S; Krasnov, George S; Lakunina, Valentina A; Snezhkina, Anastasiya V; Rozhmina, Tatiana A; Samatadze, Tatiana E; Yurkevich, Olga Yu; Zoshchuk, Svyatoslav A; Amosova, Аlexandra V; Kudryavtseva, Anna V; Muravenko, Olga V

    2017-12-28

    The species relationships within the genus Linum have already been studied several times by means of different molecular and phylogenetic approaches. Nevertheless, a number of ambiguities in phylogeny of Linum still remain unresolved. In particular, the species relationships within the sections Stellerolinum and Dasylinum need further clarification. Also, the question of independence of the species of the section Adenolinum still remains unanswered. Moreover, the relationships of L. narbonense and other species of the section Linum require further clarification. Additionally, the origin of tetraploid species of the section Linum (2n = 30) including the cultivated species L. usitatissimum has not been explored. The present study examines the phylogeny of blue-flowered species of Linum by comparisons of 5S rRNA gene sequences as well as ITS1 and ITS2 sequences of 35S rRNA genes. High-throughput sequencing has been used for analysis of multicopy rRNA gene families. In addition to the molecular phylogenetic analysis, the number and chromosomal localization of 5S and 35S rDNA sites has been determined by FISH. Our findings confirm that L. stelleroides forms a basal branch from the clade of blue-flowered flaxes which is independent of the branch formed by species of the sect. Dasylinum. The current molecular phylogenetic approaches, the cytogenetic analysis as well as different genomic DNA fingerprinting methods applied previously did not discriminate certain species within the sect. Adenolinum. The allotetraploid cultivated species L. usitatissimum and its wild ancestor L. angustifolium (2n = 30) could originate either as the result of hybridization of two diploid species (2n = 16) related to the modern L. gandiflorum and L. decumbens, or hybridization of a diploid species (2n = 16) and a diploid ancestor of modern L. narbonense (2n = 14). High-throughput sequencing of multicopy rRNA gene families allowed us to make several adjustments to the

  12. Blue gods, blue oil, and blue people.

    Science.gov (United States)

    Fairbanks, V F

    1994-09-01

    Studies of the composition of coal tar, which began in Prussia in 1834, profoundly affected the economies of Germany, Great Britain, India, and the rest of the world, as well as medicine and surgery. Such effects include the collapse of the profits of the British indigo monopoly, the growth in economic power of Germany based on coal tar chemistry, and an economic crisis in India that led to more humane tax laws and, ultimately, the independence of India and the end of the British Empire. Additional consequences were the development of antiseptic surgery and the synthesis of a wide variety of useful drugs that have eradicated infections and alleviated pain. Many of these drugs, particularly the commonly used analgesics, sulfonamides, sulfones, and local anesthetics, are derivatives of aniline, originally called "blue oil" or "kyanol." Some of these aniline derivatives, however, have also caused aplastic anemia, agranulocytosis, and methemoglobinemia (that is, "blue people"). Exposure to aniline drugs, particularly when two or three aniline drugs are taken concurrently, seems to be the commonest cause of methemoglobinemia today.

  13. Luminescence and scintillation of Ce.sup.3+./sup.-doped oxide glass with high Gd.sub.2./sub.O.sub.3./sub. concentration

    Czech Academy of Sciences Publication Activity Database

    Chewpraditkul, W.; He, X.; Chen, D.; Shen, Y.; Sheng, Q.; Yu, B.; Nikl, Martin; Kučerková, Romana; Beitlerová, Alena; Wanarak, C.; Phunpueok, A.

    2011-01-01

    Roč. 208, č. 12 (2011), s. 2830-2832 ISSN 1862-6300 R&D Projects: GA MŠk(CZ) ME10084 Institutional research plan: CEZ:AV0Z10100521 Keywords : Ce 3+ * light yield * luminescence * oxide glasses * scintillation * time-resolved luminescence Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.463, year: 2011

  14. Luminescence of high density electron-hole plasma in CdS and CdSe in a wide temperature range

    International Nuclear Information System (INIS)

    Yoshida, H.; Shionoya, S.

    1983-01-01

    Time-resolved spectra of the spontaneous luminescence of the high density electron-hole plasma (EHP) in CdS and CdSe are observed in a wide range of temperature which is surely higher than the calculated critical temperature for electron-hole liquid formation, in order to carry forward discussion on dynamic nature of the EHP previously observed in 4.2 K experiments. Spectra in the late stage are analyzed, and obtained values of the reduced bandgap energy and chemical potential are compared with those theoretically calculated for higher temperatures. The aspects of the change of the spectral shape in the late stage are hard to understand. Unfortunately no clear conclusion is drawn on the nature of the EHP produced at 4.2 K. The only thing one can say is that the condensed electron-hole liquid state, which is in equilibrium with the exciton state, is not realized. (author)

  15. 1,2,4-Triazines in the Synthesis of Bipyridine Bisphenolate ONNO Ligands and Their Highly Luminescent Tetradentate Pt(II) Complexes for Solution-Processable OLEDs.

    Science.gov (United States)

    Pander, Piotr; Bulmer, Rachel; Martinscroft, Ross; Thompson, Stuart; Lewis, Frank W; Penfold, Thomas J; Dias, Fernando B; Kozhevnikov, Valery N

    2018-04-02

    This article describes a convenient method for the synthesis of ONNO-type tetradentate 6,6'-bis(2-phenoxy)-2,2'-bipyridine (bipyridine bisphenolate, BpyBph) ligands and their platinum(II) complexes. The methodology includes the synthesis of 1,2,4-triazine precursors followed by their transformation to functionalized pyridines by the Boger reaction. Two complementary routes employing 3,3'- and 5,5'-bis-triazines allow a modification of the central pyridine rings in different positions, which was exemplified by the introduction of cyclopentene rings. The new ligands were used to prepare highly luminescent ONNO-type Pt(II) complexes. The position of the cyclopentene rings significantly influences the solubility and photophysical properties of these complexes. Derivatives with closely positioned cyclopentene rings are soluble in organic solvents and proved to be the best candidate for solution-processable organic light-emitting devices (OLEDs), showing efficient single-dopant candlelight electroluminescence.

  16. A High Power InGaN-Based Blue-Violet Laser Diode Array with a Broad-Area Stripe

    International Nuclear Information System (INIS)

    Chen Ping; Zhao De-Gang; Feng Mei-Xin; Jiang De-Sheng; Liu Zong-Shun; Yang Hui; Zhang Li-Qun; Li De-Yao; Liu Jian-Ping; Wang Hui; Zhu Jian-Jun; Zhang Shu-Ming; Zhang Bao-Shun

    2013-01-01

    An array of high power InGaN/GaN multi-quantum-well laser diodes with a broad waveguide is fabricated. The laser diode structure is grown on a GaN substrate by metal-organic chemical vapor deposition. The laser diode array consists of five emitter stripes which share common electrodes on one laser chip. The electrical and optical characteristics of the laser diode array are investigated under the pulse current injection with 10kHz frequency and 100 ns pulse width. The laser diode array emits at the wavelength of 409 nm, which is located in the blue-violet region, and the threshold current is 2.9 A. The maximum output light peak power is measured to be 7.5 W at the wavelength of 411.8 nm under the current of 25 A

  17. ECOCURE BLUE – NEW COLD BOX SYSTEM WITH ULTRA-HIGH EFFICIENCY AND AS LOW AS POSSIBLE EMISSIONS

    Directory of Open Access Journals (Sweden)

    P. N. Vacelet

    2018-01-01

    Full Text Available By omitting materials subject to the labeling requirement in part 1 cold-box resin, Düker GmbH from Laufach can achieve an impressive reduction in emissions.Emission and workplace exposure limit values represent major challenges for foundries, and are becoming increasingly important due to every stricter statutory regulations. In particular, compliance with emission guidelines is essential in safeguarding company sites, and is now of equal significance as technical and economic issues. Modern foundries such as Düker GmbH from Laufachpursue a sustainable corporate policy in which the three pillars of cost-effectiveness, social responsibility and environmental protection are accorded equal importance. Düker’s example shows how the use of the new ECOCURE BLUE technology supports environmental protection and occupational health and safety, while also facilitating efficient, highly productive core production. 

  18. Blue emission of Eu{sup 2+}-doped translucent alumina

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Yan [Kazuo Inamori School of Engineering, New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States); Wei, Hua [Scintillation Materials Research Center, University of Tennessee, Knoxville 37996 (United States); Zhang, Lihua; Kisslinger, Kim [Center for Functional Nanomaterials, Brookhaven National Laboratory, Upton, NY 11973-5000 (United States); Melcher, Charles L. [Scintillation Materials Research Center, University of Tennessee, Knoxville 37996 (United States); Wu, Yiquan, E-mail: wuy@alfred.edu [Kazuo Inamori School of Engineering, New York State College of Ceramics, Alfred University, Alfred, NY 14802 (United States)

    2015-12-15

    Inorganic scintillators are very important in medical and industrial measuring systems in the detection and measurement of ionizing radiation. In addition to Ce{sup 3+}, a widely used dopant ion in oxide scintillators, divalent Europium (Eu{sup 2+}) has shown promise as a high-luminescence, fast-response luminescence center useful in the detection of ionizing radiation. In this research, aluminum oxide (Al{sub 2}O{sub 3}) was studied as a host material for the divalent europium ion. Polycrystalline samples of Eu{sup 2+}-doped translucent Al{sub 2}O{sub 3} were fabricated, and room temperature luminescence behavior was observed. Al{sub 2}O{sub 3} ceramics doped with 0.1 at% Eu{sup 2+} were fabricated with a relative density of 99.75% theoretical density and in-line transmittance of 22% at a wavelength of 800 nm. The ceramics were processed by a gel-casting method, followed by sintering under high vacuum. The gelling agent, a copolymer of isobutylene and maleic anhydride, is marketed under the commercial name ISOBAM, and has the advantage of simultaneously acting as both a gelling agent and as a dispersant. The microstructure and composition of the vacuum-sintered Eu{sup 2+}:Al{sub 2}O{sub 3} were characterized by Scanning Electric Microscopy (SEM), Transmission Electron Microscopy (TEM), and Energy-dispersive X-ray spectroscopy (EDS). The phase composition was determined by X-ray diffraction measurements (XRD) combined with Rietveld analysis. The photoluminescence behavior of the Eu{sup 2+}:Al{sub 2}O{sub 3} was characterized using UV light as the excitation source, which emitted blue emission at 440 nm. The radio-luminescence of Eu{sup 2+}:Al{sub 2}O{sub 3} was investigated by illumination with X-ray radiation, showing three emission bands at 376 nm, 575 nm and 698 nm. Multiple level traps at different depths were detected in the Eu{sup 2+}:Al{sub 2}O{sub 3} by employing thermoluminescence measurements. - Highlights: • Eu{sup 2+} : Al{sub 2}O{sub 3} was

  19. One pot synthesis of highly luminescent polyethylene glycol anchored carbon dots functionalized with a nuclear localization signal peptide for cell nucleus imaging.

    Science.gov (United States)

    Yang, Lei; Jiang, Weihua; Qiu, Lipeng; Jiang, Xuewei; Zuo, Daiying; Wang, Dongkai; Yang, Li

    2015-04-14

    Strong blue fluorescent polyethylene glycol (PEG) anchored carbon nitride dots (CDs@PEG) with a high quantum yield (QY) of 75.8% have been synthesized by a one step hydrothermal treatment. CDs with a diameter of ca. 6 nm are well dispersed in water and present a graphite-like structure. Photoluminescence (PL) studies reveal that CDs display excitation-dependent behavior and are stable under various test conditions. Based on the as-prepared CDs, we designed novel cell nucleus targeting imaging carbon dots functionalized with a nuclear localization signal (NLS) peptide. The favourable biocompatibilities of CDs and NLS modified CDs (NLS-CDs) are confirmed by in vitro cytotoxicity assays. Importantly, intracellular localization experiments in MCF7 and A549 cells demonstrate that NLS-CDs could be internalized in the nucleus and show blue light, which indicates that CDs may serve as cell nucleus imaging probes.

  20. Study of the luminescence properties of a natural amazonite

    Energy Technology Data Exchange (ETDEWEB)

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

    2011-09-15

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

  1. Highly luminescent InP/GaP/ZnS QDs emitting in the entire color range via a heating up process.

    Science.gov (United States)

    Park, Joong Pill; Lee, Jae-Joon; Kim, Sang-Wook

    2016-07-20

    InP-based quantum dots (QDs) have attracted much attention for use in optical applications, and several types of QDs such as InP/ZnS, InP/ZnSeS, and InP/GaP/ZnS have been developed. However, early synthetic methods that involved rapid injection at high temperatures have not been able to reproducibly produce the required optical properties. They were also not able to support commercialization efforts successfully. Herein, we introduce a simple synthetic method for InP/GaP/ZnS core/shell/shell QDs via a heating process. The reaction was completed within 0.5 h and a full color range from blue to red was achieved. For emitting blue color, t-DDT was applied to prevent particle growth. From green to orange, color variation was achieved by adjusting the quantity of myristic acid. Utilizing large quantities of gallium chloride led to red color. With this method, we produced high-quality InP/GaP/ZnS QDs (blue QY: ~40%, FWHM: 50 nm; green QY: ~85%, FWHM: 41 nm; red QY: ~60%, FWHM: 65 nm). We utilized t-DDT as a new sulfur source. Compared with n-DDT, t-DDT was more reactive, which allowed for the formation of a thicker shell.

  2. Highly luminescent InP/GaP/ZnS QDs emitting in the entire color range via a heating up process

    Science.gov (United States)

    Park, Joong Pill; Lee, Jae-Joon; Kim, Sang-Wook

    2016-07-01

    InP-based quantum dots (QDs) have attracted much attention for use in optical applications, and several types of QDs such as InP/ZnS, InP/ZnSeS, and InP/GaP/ZnS have been developed. However, early synthetic methods that involved rapid injection at high temperatures have not been able to reproducibly produce the required optical properties. They were also not able to support commercialization efforts successfully. Herein, we introduce a simple synthetic method for InP/GaP/ZnS core/shell/shell QDs via a heating process. The reaction was completed within 0.5 h and a full color range from blue to red was achieved. For emitting blue color, t-DDT was applied to prevent particle growth. From green to orange, color variation was achieved by adjusting the quantity of myristic acid. Utilizing large quantities of gallium chloride led to red color. With this method, we produced high-quality InP/GaP/ZnS QDs (blue QY: ~40%, FWHM: 50 nm green QY: ~85%, FWHM: 41 nm red QY: ~60%, FWHM: 65 nm). We utilized t-DDT as a new sulfur source. Compared with n-DDT, t-DDT was more reactive, which allowed for the formation of a thicker shell.

  3. Plasmon-enhanced optically stimulated luminescence

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-10-15

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

  4. Plasmon-enhanced optically stimulated luminescence

    International Nuclear Information System (INIS)

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

    2015-10-01

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

  5. FY 1995 Blue Book: High Performance Computing and Communications: Technology for the National Information Infrastructure

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — The Federal High Performance Computing and Communications HPCC Program was created to accelerate the development of future generations of high performance computers...

  6. Near-Infrared Quantum Cutting Long Persistent Luminescence

    OpenAIRE

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

    2016-01-01

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

  7. Na-rich feldspar as a luminescence dosimeter in infrared stimulated luminescence (IRSL) dating

    DEFF Research Database (Denmark)

    Sohbati, Reza; Murray, Andrew; Jain, Mayank

    2013-01-01

    on geological origin and erosion history, but the dosimetry of K-rich feldspar grains extracted from rocks is complicated because the internal dose rate is very dependent on the original feldspar grain size. The in situ grain size information is lost during the crushing process used to separate the grains...... settings for which independent age control is available. The blue and yellow luminescence emissions are measured for IR stimulation at 50 °C (IR50), and post-IR IR stimulation at 290 °C (pIRIR290). Thermal stability experiments imply that the corresponding signals in both emissions have comparable thermal...... stabilities and that all signals have similar recombination kinetics and are thermally stable over geological timescales. The IR50 doses measured using blue and yellow emissions are similar to or lower than quartz doses while pIRIR290 blue doses are higher than those from yellow emission and quartz doses...

  8. Blue 450nm high power semiconductor continuous wave laser bars exceeding rollover output power of 80W

    Science.gov (United States)

    König, H.; Lell, A.; Stojetz, B.; Ali, M.; Eichler, C.; Peter, M.; Löffler, A.; Strauss, U.; Baumann, M.; Balck, A.; Malchus, J.; Krause, V.

    2018-02-01

    Industrial material processing like cutting or welding of metals is rather energy efficient using direct diode or diode pumped solid state lasers. However, many applications cannot be addressed by established infrared laser technology due to fundamental material properties of the workpiece: For example materials like copper or gold have too low absorption in the near infrared wavelength range to be processed efficiently by use of existing high power laser systems. The huge interest to enable high power kW systems with more suitable wavelengths in the blue spectral range triggered the German funded research project 'BLAULAS': Therein the feasibility and capability of CW operating high power laser bars based on the GaN material system was investigated by Osram and Laserline. High performance bars were enabled by defeating fundamental challenges like material quality as well as the chip processes, both of which differ significantly from well-known IR laser bars. The research samples were assembled on actively cooled heat sinks with hard solder technology. For the first time an output power of 98W per bar at 60A drive current was achieved. Conversion efficiency as high as 46% at 50W output power was demonstrated.

  9. Development of a Computational Steering Framework for High Performance Computing Environments on Blue Gene/P Systems

    KAUST Repository

    Danani, Bob K.

    2012-07-01

    Computational steering has revolutionized the traditional workflow in high performance computing (HPC) applications. The standard workflow that consists of preparation of an application’s input, running of a simulation, and visualization of simulation results in a post-processing step is now transformed into a real-time interactive workflow that significantly reduces development and testing time. Computational steering provides the capability to direct or re-direct the progress of a simulation application at run-time. It allows modification of application-defined control parameters at run-time using various user-steering applications. In this project, we propose a computational steering framework for HPC environments that provides an innovative solution and easy-to-use platform, which allows users to connect and interact with running application(s) in real-time. This framework uses RealityGrid as the underlying steering library and adds several enhancements to the library to enable steering support for Blue Gene systems. Included in the scope of this project is the development of a scalable and efficient steering relay server that supports many-to-many connectivity between multiple steered applications and multiple steering clients. Steered applications can range from intermediate simulation and physical modeling applications to complex computational fluid dynamics (CFD) applications or advanced visualization applications. The Blue Gene supercomputer presents special challenges for remote access because the compute nodes reside on private networks. This thesis presents an implemented solution and demonstrates it on representative applications. Thorough implementation details and application enablement steps are also presented in this thesis to encourage direct usage of this framework.

  10. Azure B, a metabolite of methylene blue, is a high-potency, reversible inhibitor of monoamine oxidase

    Energy Technology Data Exchange (ETDEWEB)

    Petzer, Anél, E-mail: 12264954@nwu.ac.za [Unit for Drug Research and Development, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520 (South Africa); Harvey, Brian H. [Division of Pharmacology, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520 (South Africa); Wegener, Gregers [Centre for Psychiatric Research, Aarhus University Hospital-Risskov, Skovagervej 2, 8240 Risskov (Denmark); Petzer, Jacobus P. [Division of Pharmaceutical Chemistry, School of Pharmacy, North-West University, Private Bag X6001, Potchefstroom, 2520 (South Africa)

    2012-02-01

    Methylene blue (MB) has been shown to act at multiple cellular and molecular targets and as a result possesses diverse medical applications. Among these is a high potency reversible inhibition of monoamine oxidase A (MAO-A) that may, at least in part, underlie its adverse effects but also its psycho- and neuromodulatory actions. MB is metabolized to yield N-demethylated products of which azure B, the monodemethyl species, is the major metabolite. Similar to MB, azure B also displays a variety of biological activities and may therefore contribute to the pharmacological profile of MB. Based on these observations, the present study examines the interactions of azure B with recombinant human MAO-A and -B. The results show that azure B is a potent MAO-A inhibitor (IC{sub 50} = 11 nM), approximately 6-fold more potent than is MB (IC{sub 50} = 70 nM) under identical conditions. Measurements of the time-dependency of inhibition suggest that the interaction of azure B with MAO-A is reversible. Azure B also reversibly inhibits the MAO-B isozyme with an IC{sub 50} value of 968 nM. These results suggest that azure B may be a hitherto under recognized contributor to the pharmacology and toxicology of MB by blocking central and peripheral MAO-A activity and as such needs to be considered during its use in humans and animals. Highlights: ► Methylene blue (MB) is a known potent MAO-A inhibitor. ► Azure B, the major metabolite of MB, is more potent as a MAO-A inhibitor. ► Azure B may be a contributor to the CNS pharmacology and toxicology of MB.

  11. Solution-processed small molecules as mixed host for highly efficient blue and white phosphorescent organic light-emitting diodes.

    Science.gov (United States)

    Fu, Qiang; Chen, Jiangshan; Shi, Changsheng; Ma, Dongge

    2012-12-01

    The widely used hole-transporting host 4,4',4″-tris(N-carbazolyl)-triphenylamine (TCTA) blended with either a hole-transporting or an electron-transporting small-molecule material as a mixed-host was investigated in the phosphorescent organic light-emitting diodes (OLEDs) fabricated by the low-cost solution-process. The performance of the solution-processed OLEDs was found to be very sensitive to the composition of the mixed-host systems. The incorporation of the hole-transporting 1,1-bis[(di-4-tolylamino)phenyl]cyclohexane (TAPC) into TCTA as the mixed-host was demonstrated to greatly reduce the driving voltage and thus enhance the efficiency due to the improvement of hole injection and transport. On the basis of the mixed-host of TCTA:TAPC, we successfully fabricated low driving voltage and high efficiency blue and white phosphorescent OLEDs. A maximum forward viewing current efficiency of 32.0 cd/A and power efficiency of 25.9 lm/W were obtained in the optimized mixed-host blue OLED, which remained at 29.6 cd/A and 19.1 lm/W at the luminance of 1000 cd/m(2) with a driving voltage as low as 4.9 V. The maximum efficiencies of 37.1 cd/A and 32.1 lm/W were achieved in a single emissive layer white OLED based on the TCTA:TAPC mixed-host. Even at 1000 cd/m(2), the efficiencies still reach 34.2 cd/A and 23.3 lm/W and the driving voltage is only 4.6 V, which is comparable to those reported from the state-of-the-art vacuum-evaporation deposited white OLEDs.

  12. Positron-Induced Luminescence

    Science.gov (United States)

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

    2018-04-01

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

  13. Electron-Rich 4-Substituted Spirobifluorenes: Toward a New Family of High Triplet Energy Host Materials for High-Efficiency Green and Sky Blue Phosphorescent OLEDs.

    Science.gov (United States)

    Quinton, Cassandre; Thiery, Sébastien; Jeannin, Olivier; Tondelier, Denis; Geffroy, Bernard; Jacques, Emmanuel; Rault-Berthelot, Joëlle; Poriel, Cyril

    2017-02-22

    We report herein a detailed structure-properties relationship study of the first examples of electron-rich 4-substituted spirobifluorenes for organic electronic applications, namely, 4-phenyl-N-carbazole-spirobifluorene (4-PhCz-SBF) and 4-(3,4,5-trimethoxyphenyl)-spirobifluorene (4-Ph(OMe) 3 -SBF). The incorporation of the electron-rich moieties in the ortho position of the biphenyl linkage (position C4) induces unique properties, very different from those previously described in the literature for this family of semiconductors. Both dyes can be readily synthesized, possess high triplet energies and excellent thermal stability, and their HOMO energy levels are highly increased compared to those of other 4-substituted SBFs. We also provide in this work the first rationalization of the peculiar fluorescence of 4-substituted SBFs. Finally, the present dyes have been successfully incorporated as host in green and blue phosphorescent organic light-emitting diodes with high performance either for the green (EQE of 20.2%) or the blue color (EQE of 9.6%). These performances are, to the best of our knowledge, among the highest reported to date for 4-substituted SBF derivatives.

  14. FY 1992 Blue Book: Grand Challenges: High Performance Computing and Communications

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — High performance computing and computer communications networks are becoming increasingly important to scientific advancement, economic competition, and national...

  15. FY 1993 Blue Book: Grand Challenges 1993: High Performance Computing and Communications

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — High performance computing and computer communications networks are becoming increasingly important to scientific advancement, economic competition, and national...

  16. FY 1996 Blue Book: High Performance Computing and Communications: Foundations for America`s Information Future

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — The Federal High Performance Computing and Communications HPCC Program will celebrate its fifth anniversary in October 1996 with an impressive array of...

  17. FY 1997 Blue Book: High Performance Computing and Communications: Advancing the Frontiers of Information Technology

    Data.gov (United States)

    Networking and Information Technology Research and Development, Executive Office of the President — The Federal High Performance Computing and Communications HPCC Program will celebrate its fifth anniversary in October 1996 with an impressive array of...

  18. Realizing Highly Efficient Solution-Processed Homojunction-Like Sky-Blue OLEDs by Using Thermally Activated Delayed Fluorescent Emitters Featuring an Aggregation-Induced Emission Property.

    Science.gov (United States)

    Wu, Kailong; Wang, Zian; Zhan, Lisi; Zhong, Cheng; Gong, Shaolong; Xie, Guohua; Yang, Chuluo

    2018-04-05

    Two new blue emitters, i.e., bis-[2-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( o-ACSO2) and bis-[3-(9,9-dimethyl-9,10-dihydroacridine)-phenyl]-sulfone ( m-ACSO2), with reserved fine thermally activated delayed fluorescent (TADF) nature and simply tuned thermal and optoelectronic properties, were synthesized by isomer engineering. The meta-linking compound, i.e., m-ACSO2, obtains the highest photoluminescence quantum yield with a small singlet-triplet energy gap, a moderate delayed fluorescent lifetime, excellent solubility, and neat film homogeneity. Due to its unique aggregation-induced emission (AIE) character, neat film-based heterojunction-like organic light-emitting diodes (OLEDs) are achievable. By inserting an excitonic inert exciton-blocking layer, the PN heterojunction-like emission accompanied by intefacial exciplex was shifted to a homojunction-like channel mainly from the AIE emitter itself, providing a new tactic to generate efficient blue color from neat films. The solution-processed nondoped sky-blue OLED employing m-ACSO2 as emitter with homojunction-like emission achieved a maximum external quantum efficiency of 17.2%. The design strategies presented herein provide practical methods to construct efficient blue TADF dyes and realize high-performance blue TADF devices.

  19. A facile approach to prepare porous cup-stacked carbon nanotube with high performance in adsorption of methylene blue.

    Science.gov (United States)

    Gong, Jiang; Liu, Jie; Jiang, Zhiwei; Wen, Xin; Mijowska, Ewa; Tang, Tao; Chen, Xuecheng

    2015-05-01

    Novel porous cup-stacked carbon nanotube (P-CSCNT) with special stacked morphology consisting of many truncated conical graphene layers was synthesized by KOH activating CSCNT from polypropylene. The morphology, microstructure, textural property, phase structure, surface element composition and thermal stability of P-CSCNT were investigated by field-emission scanning electron microscope, transmission electron microscope (TEM), high-resolution TEM, N2 sorption, X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy and thermal gravimetric analysis. A part of oblique graphitic layers were etched by KOH, and many holes with a diameter of several to a doze of nanometers connecting inner tube with outside were formed, which endowed P-CSCNT with high specific surface area (558.7 m(2)/g), large pore volume (1.993 cm(3)/g) and abundant surface functional groups. Subsequently, P-CSCNT was used for adsorption of methylene blue (MB) from wastewater. Langmuir model closely fitted the adsorption results, and the maximum adsorption capacity of P-CSCNT was as high as 319.1mg/g. This was ascribed to multiple adsorption mechanisms including pore filling, hydrogen bonding, π-π and electrostatic interactions. Pseudo second-order kinetic model was more valid to describe the adsorption behavior. Besides, P-CSCNT showed good recyclablity and reusability. These results demonstrated that P-CSCNT had potential application in wastewater treatment. Copyright © 2015 Elsevier Inc. All rights reserved.

  20. High-Performance Doping-Free Hybrid White OLEDs Based on Blue Aggregation-Induced Emission Luminogens.

    Science.gov (United States)

    Liu, Baiquan; Nie, Han; Lin, Gengwei; Hu, Shiben; Gao, Dongyu; Zou, Jianhua; Xu, Miao; Wang, Lei; Zhao, Zujin; Ning, Honglong; Peng, Junbiao; Cao, Yong; Tang, Ben Zhong

    2017-10-04

    Doping-free white organic light-emitting diodes (DF-WOLEDs) have aroused research interest because of their simple properties. However, to achieve doping-free hybrid WOLEDs (DFH-WOLEDs), avoiding aggregation-caused quenching is challenging. Herein, blue luminogens with aggregation-induced emission (AIE) characteristics, for the first time, have been demonstrated to develop DFH-WOLEDs. Unlike previous DFH-WOLEDs, both thin (10 nm) AIE luminogen (AIEgen) can be used for devices, enhancing the flexibility. Two-color devices show (i) pure-white emission, (ii) high CRI (85), and (iii) high efficiency. Particularly, 19.0 lm W 1- is the highest for pure-white DF-WOLEDs, while 35.0 lm W 1- is the best for two-color hybrid WOLEDs with CRI ≥ 80. A three-color DFH-WOLED shows broad color-correlated temperature span (2301-11628 K), (i) the first sunlight-like OLED (2500-8000 K) operating at low voltages, (ii) the broadest span among sunlight-like OLED, and (iii) possesses comparable efficiency with the best doping counterpart. Another three-color DFH-WOLED exhibits CRI > 90 at ≥3000 cd m -2 , (i) the first DF-WOLED with CRI ≥ 90 at high luminances, and (ii) the CRI (92.8) is not only the highest among AIE-based WOLEDs but also the highest among DF-WOLEDs. Such findings may unlock an alternative concept to develop DFH-WOLEDs.

  1. Manipulation of Thermally Activated Delayed Fluorescence of Blue Exciplex Emission: Fully Utilizing Exciton Energy for Highly Efficient Organic Light Emitting Diodes with Low Roll-Off.

    Science.gov (United States)

    Wang, Zixing; Wang, Hedan; Zhu, Jun; Wu, Peng; Shen, Bowen; Dou, Dehai; Wei, Bin

    2017-06-28

    The application of exciplex energy has become a unique way to achieve organic light-emitting diodes (OLEDs) with high efficiencies, low turn-on voltage, and low roll-off. Novel δ-carboline derivatives with high triplet energy (T 1 ≈ 2.92 eV) and high glass transition temperature (T g ≈ 153 °C) were employed to manipulate exciplex emissions in this paper. Deep blue (peak at 436 nm) and pure blue (peak at 468 nm) thermally activated delayed fluorescence (TADF) of exciplex OLEDs were demonstrated by utilizing them as emitters with the maximum current efficiency (CE) of 4.64 cd A -1 , power efficiency (PE) of 2.91 lm W -1 , and external quantum efficiency (EQE) of 2.36%. Highly efficient blue phosphorescent OLEDs doped with FIrpic showed a maximum CE of 55.6 cd A -1 , PE of 52.9 lm W -1 , and EQE of 24.6% respectively with very low turn on voltage at 2.7 V. The devices still remain high CE of 46.5 cd A -1 at 100 cd m -2 , 45.4 cd A -1 at 1000 cd m -2 and 42.3 cd A -1 at 5000 cd m -2 with EQE close to 20% indicating low roll-off. Manipulating blue exciplex emissions by chemical structure gives an ideal strategy to fully utilize all exciton energies for lighting of OLEDs.

  2. Ratiometric highly sensitive luminescent nanothermometers working in the room temperature range. Applications to heat propagation in nanofluids

    Science.gov (United States)

    Brites, Carlos D. S.; Lima, Patrícia P.; Silva, Nuno J. O.; Millán, Angel; Amaral, Vitor S.; Palacio, Fernando; Carlos, Luís D.

    2013-07-01

    There is an increasing demand for accurate, non-invasive and self-reference temperature measurements as technology progresses into the nanoscale. This is particularly so in micro- and nanofluidics where the comprehension of heat transfer and thermal conductivity mechanisms can play a crucial role in areas as diverse as energy transfer and cell physiology. Here we present two luminescent ratiometric nanothermometers based on a magnetic core coated with an organosilica shell co-doped with Eu3+ and Tb3+ chelates. The design of the hybrid host and chelate ligands permits the working of the nanothermometers in a nanofluid at 293-320 K with an emission quantum yield of 0.38 +/- 0.04, a maximum relative sensitivity of 1.5% K-1 at 293 K and a spatio-temporal resolution (constrained by the experimental setup) of 64 × 10-6 m/150 × 10-3 s (to move out of 0.4 K - the temperature uncertainty). The heat propagation velocity in the nanofluid, (2.2 +/- 0.1) × 10-3 m s-1, was determined at 294 K using the nanothermometers' Eu3+/Tb3+ steady-state spectra. There is no precedent of such an experimental measurement in a thermographic nanofluid, where the propagation velocity is measured from the same nanoparticles used to measure the temperature.There is an increasing demand for accurate, non-invasive and self-reference temperature measurements as technology progresses into the nanoscale. This is particularly so in micro- and nanofluidics where the comprehension of heat transfer and thermal conductivity mechanisms can play a crucial role in areas as diverse as energy transfer and cell physiology. Here we present two luminescent ratiometric nanothermometers based on a magnetic core coated with an organosilica shell co-doped with Eu3+ and Tb3+ chelates. The design of the hybrid host and chelate ligands permits the working of the nanothermometers in a nanofluid at 293-320 K with an emission quantum yield of 0.38 +/- 0.04, a maximum relative sensitivity of 1.5% K-1 at 293 K and a spatio

  3. Dress Codes Blues: An Exploration of Urban Students' Reactions to a Public High School Uniform Policy

    Science.gov (United States)

    DaCosta, Kneia

    2006-01-01

    This qualitative investigation explores the responses of 22 U.S. urban public high school students when confronted with their newly imposed school uniform policy. Specifically, the study assessed students' appraisals of the policy along with compliance and academic performance. Guided by ecological human development perspectives and grounded in…

  4. A quality assurance initiative for commercial-scale production in high-throughput cryopreservation of blue catfish sperm.

    Science.gov (United States)

    Hu, E; Liao, T W; Tiersch, T R

    2013-10-01

    Cryopreservation of fish sperm has been studied for decades at a laboratory (research) scale. However, high-throughput cryopreservation of fish sperm has recently been developed to enable industrial-scale production. This study treated blue catfish (Ictalurus furcatus) sperm high-throughput cryopreservation as a manufacturing production line and initiated quality assurance plan development. The main objectives were to identify: (1) the main production quality characteristics; (2) the process features for quality assurance; (3) the internal quality characteristics and their specification designs; (4) the quality control and process capability evaluation methods, and (5) the directions for further improvements and applications. The essential product quality characteristics were identified as fertility-related characteristics. Specification design which established the tolerance levels according to demand and process constraints was performed based on these quality characteristics. Meanwhile, to ensure integrity throughout the process, internal quality characteristics (characteristics at each quality control point within process) that could affect fertility-related quality characteristics were defined with specifications. Due to the process feature of 100% inspection (quality inspection of every fish), a specific calculation method, use of cumulative sum (CUSUM) control charts, was applied to monitor each quality characteristic. An index of overall process evaluation, process capacity, was analyzed based on in-control process and the designed specifications, which further integrates the quality assurance plan. With the established quality assurance plan, the process could operate stably and quality of products would be reliable. Copyright © 2013 Elsevier Inc. All rights reserved.

  5. Synthesis, characterization and electroluminescence of two highly-twisted non-doped blue light-emitting materials

    Science.gov (United States)

    Gong, Xiaojie; Pan, Yipeng; Xie, Xiang; Tong, Tong; Chen, Runfeng; Gao, Deqing

    2018-04-01

    Two pyrene derivatives, substituted with 2-methylnaphthalene units on 1,3-position and 1,6-position of pyrene backbones, were designed and synthesized. DFT calculation confirmed that the two molecules were highly twisted and the dihedral angles between pyrene backbone and naphthalene unit were over 80°, being attributed to the steric hindrance of ortho-methyl group and the substitution position of pyrene itself. As a result, the intermolecular aggregation was greatly inhibited in the solid state, being beneficial for suppressing the fluorescence quenching. By analyzing the optical and thermal properties, it was found that the π-π conjugation extension could be adjusted and a balance for high fluorescent efficiency and avoiding quenching at the same time could be reached, which may guide the molecular design in the future. The electroluminescence properties of the non-doped devices were enhanced with the double hole-transporting layers by optimizing the energy level matching. The stable blue EL emission, with the Commission Internationaled'Eclairage (CIEx,y) color coordinates of (0.15, 0.13) and (0.15, 0.11) at 7, 8, 9 and 10 V respectively, was obtained.

  6. Changes in the Mg profile and in dislocations induced by high temperature annealing of blue LEDs

    Science.gov (United States)

    Meneghini, M.; Trivellin, N.; Berti, M.; Cesca, T.; Gasparotto, A.; Vinattieri, A.; Bogani, F.; Zhu, D.; Humphreys, C. J.; Meneghesso, G.; Zanoni, E.

    2013-03-01

    The efficiency of the injection and recombination processes in InGaN/GaN LEDs is governed by the properties of the active region of the devices, which strongly depend on the conditions used for the growth of the epitaxial material. To improve device quality, it is very important to understand how the high temperatures used during the growth process can modify the quality of the epitaxial material. With this paper we present a study of the modifications in the properties of InGaN/GaN LED structures induced by high temperature annealing: thermal stress tests were carried out at 900 °C, in nitrogen atmosphere, on selected samples. The efficiency and the recombination dynamics were evaluated by photoluminescence measurements (both integrated and time-resolved), while the properties of the epitaxial material were studied by Secondary Ion Mass Spectroscopy (SIMS) and Rutherford Backscattering (RBS) channeling measurements. Results indicate that exposure to high temperatures may lead to: (i) a significant increase in the photoluminescence efficiency of the devices; (ii) a decrease in the parasitic emission bands located between 380 nm and 400 nm; (iii) an increase in carrier lifetime, as detected by time-resolved photoluminescence measurements. The increase in device efficiency is tentatively ascribed to an improvement in the crystallographic quality of the samples.

  7. Multifunctional Optical Sensors for Nanomanometry and Nanothermometry: High-Pressure and High-Temperature Upconversion Luminescence of Lanthanide-Doped Phosphates-LaPO4/YPO4:Yb3+-Tm3.

    Science.gov (United States)

    Runowski, Marcin; Shyichuk, Andrii; Tymiński, Artur; Grzyb, Tomasz; Lavín, Víctor; Lis, Stefan

    2018-05-23

    Upconversion luminescence of nano-sized Yb 3+ and Tm 3+ codoped rare earth phosphates, that is, LaPO 4 and YPO 4 , has been investigated under high-pressure (HP, up to ∼25 GPa) and high-temperature (293-773 K) conditions. The pressure-dependent luminescence properties of the nanocrystals, that is, energy red shift of the band centroids, changes of the band ratios, shortening of upconversion lifetimes, and so forth, make the studied nanomaterials suitable for optical pressure sensing in nanomanometry. Furthermore, thanks to the large energy difference (∼1800 cm -1 ), the thermalized states of Tm 3+ ions are spectrally well-separated, providing high-temperature resolution, required in optical nanothermometry. The temperature of the system containing such active nanomaterials can be determined on the basis of the thermally induced changes of the Tm 3+ band ratio ( 3 F 2,3 → 3 H 6 / 3 H 4 → 3 H 6 ), observed in the emission spectra. The advantage of such upconverting optical sensors is the use of near-infrared light, which is highly penetrable for many materials. The investigated nanomanometers/nanothermometers have been successfully applied, as a proof-of-concept of a novel bimodal optical gauge, for the determination of the temperature of the heated system (473 K), which was simultaneously compressed under HP (1.5 and 5 GPa).

  8. Posthuman blues

    CERN Document Server

    Tonnies, Mac

    2013-01-01

    Posthuman Blues, Vol. I is first volume of the edited version of the popular weblog maintained by author Mac Tonnies from 2003 until his tragic death in 2009. Tonnies' blog was a pastiche of his original fiction, reflections on his day-to-day life, trenchant observations of current events, and thoughts on an eclectic range of material he culled from the Internet. What resulted was a remarkably broad portrait of a thoughtful man and the complex times in which he lived, rendered with intellige...

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

    International Nuclear Information System (INIS)

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

    2010-01-01

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

  10. High-Resolution Forest Canopy Height Estimation in an African Blue Carbon Ecosystem

    Science.gov (United States)

    Lagomasino, David; Fatoyinbo, Temilola; Lee, Seung-Kuk; Simard, Marc

    2015-01-01

    Mangrove forests are one of the most productive and carbon dense ecosystems that are only found at tidally inundated coastal areas. Forest canopy height is an important measure for modeling carbon and biomass dynamics, as well as land cover change. By taking advantage of the flat terrain and dense canopy cover, the present study derived digital surface models (DSMs) using stereophotogrammetric techniques on high-resolution spaceborne imagery (HRSI) for southern Mozambique. A mean-weighted ground surface elevation factor was subtracted from the HRSI DSM to accurately estimate the canopy height in mangrove forests in southern Mozambique. The mean and H100 tree height measured in both the field and with the digital canopy model provided the most accurate results with a vertical error of 1.18-1.84 m, respectively. Distinct patterns were identified in the HRSI canopy height map that could not be discerned from coarse shuttle radar topography mission canopy maps even though the mode and distribution of canopy heights were similar over the same area. Through further investigation, HRSI DSMs have the potential of providing a new type of three-dimensional dataset that could serve as calibration/validation data for other DSMs generated from spaceborne datasets with much larger global coverage. HSRI DSMs could be used in lieu of Lidar acquisitions for canopy height and forest biomass estimation, and be combined with passive optical data to improve land cover classifications.

  11. Breadnut peel as a highly effective low-cost biosorbent for methylene blue: Equilibrium, thermodynamic and kinetic studies

    Directory of Open Access Journals (Sweden)

    Linda B.L. Lim

    2017-05-01

    Full Text Available This work reports the potential use of peel of breadnut, Artocarpus camansi, as an effective low-cost biosorbent for the removal of methylene blue (MB. Oven dried A. camansi peel (ACP, which had a point of zero charge at pH = 4.8, showed maximum biosorption capacity which was far superior to most literature reported fruit biomasses, including samples that have been activated. Isotherm studies on biosorption of MB onto ACP gave a maximum biosorption capacity of 409 mg g−1. The Langmuir model was found to give the best fit among various isotherm models investigated and error analyses performed. Kinetics studies were fast with 50% dye being removed in less than 8 min from a 50 mg L−1 dye solution and further, kinetics followed the pseudo second order. Thermodynamic studies indicated that the biosorption process was both spontaneous and exothermic. Fourier transform infrared (FT-IR of ACP before and after MB adsorption was investigated. It can be concluded that oven dried breadnut peel is a highly promising low-cost biosorbent with great potential for the removal of MB.

  12. Deep Learning Identifies High-z Galaxies in a Central Blue Nugget Phase in a Characteristic Mass Range

    Science.gov (United States)

    Huertas-Company, M.; Primack, J. R.; Dekel, A.; Koo, D. C.; Lapiner, S.; Ceverino, D.; Simons, R. C.; Snyder, G. F.; Bernardi, M.; Chen, Z.; Domínguez-Sánchez, H.; Lee, C. T.; Margalef-Bentabol, B.; Tuccillo, D.

    2018-05-01

    We use machine learning to identify in color images of high-redshift galaxies an astrophysical phenomenon predicted by cosmological simulations. This phenomenon, called the blue nugget (BN) phase, is the compact star-forming phase in the central regions of many growing galaxies that follows an earlier phase of gas compaction and is followed by a central quenching phase. We train a convolutional neural network (CNN) with mock “observed” images of simulated galaxies at three phases of evolution— pre-BN, BN, and post-BN—and demonstrate that the CNN successfully retrieves the three phases in other simulated galaxies. We show that BNs are identified by the CNN within a time window of ∼0.15 Hubble times. When the trained CNN is applied to observed galaxies from the CANDELS survey at z = 1–3, it successfully identifies galaxies at the three phases. We find that the observed BNs are preferentially found in galaxies at a characteristic stellar mass range, 109.2–10.3 M ⊙ at all redshifts. This is consistent with the characteristic galaxy mass for BNs as detected in the simulations and is meaningful because it is revealed in the observations when the direct information concerning the total galaxy luminosity has been eliminated from the training set. This technique can be applied to the classification of other astrophysical phenomena for improved comparison of theory and observations in the era of large imaging surveys and cosmological simulations.

  13. Luminescence imaging using radionuclides: a potential application in molecular imaging

    International Nuclear Information System (INIS)

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

    2011-01-01

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

  14. The nature of unusual luminescence in natural calcite, CaCO3

    Energy Technology Data Exchange (ETDEWEB)

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

    2008-11-01

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

  15. Geology along the Blue Ridge Parkway in Virginia

    Science.gov (United States)

    Carter, Mark W.; Southworth, C. Scott; Tollo, Richard P.; Merschat, Arthur J.; Wagner, Sara; Lazor, Ava; Aleinikoff, John N.

    2017-01-01

    Detailed geologic mapping and new SHRIMP (sensitive high-resolution ion microprobe) U-Pb zircon, Ar/Ar, Lu-Hf, 14C, luminescence (optically stimulated), thermochronology (fission-track), and palynology reveal the complex Mesoproterozoic to Quaternary geology along the ~350 km length of the Blue Ridge Parkway in Virginia. Traversing the boundary of the central and southern Appalachians, rocks along the parkway showcase the transition from the para-autochthonous Blue Ridge anticlinorium of northern and central Virginia to the allochthonous eastern Blue Ridge in southern Virginia. From mile post (MP) 0 near Waynesboro, Virginia, to ~MP 124 at Roanoke, the parkway crosses the unconformable to faulted boundary between Mesoproterozoic basement in the core of the Blue Ridge anticlinorium and Neoproterozoic to Cambrian metasedimentary and metavolcanic cover rocks on the western limb of the structure. Mesoproterozoic basement rocks comprise two groups based on SHRIMP U-Pb zircon geochronology: Group I rocks (1.2-1.14 Ga) are strongly foliated orthogneisses, and Group II rocks (1.08-1.00 Ga) are granitoids that mostly lack obvious Mesoproterozoic deformational features.Neoproterozoic to Cambrian cover rocks on the west limb of the anticlinorium include the Swift Run and Catoctin Formations, and constituent formations of the Chilhowee Group. These rocks unconformably overlie basement, or abut basement along steep reverse faults. Rocks of the Chilhowee Group are juxtaposed against Cambrian rocks of the Valley and Ridge province along southeast- and northwest-dipping, high-angle reverse faults. South of the James River (MP 64), Chilhowee Group and basement rocks occupy the hanging wall of the nearly flat-lying Blue Ridge thrust fault and associated splays.South of the Red Valley high-strain zone (MP 144.5), the parkway crosses into the wholly allochthonous eastern Blue Ridge, comprising metasedimentary and meta-igneous rocks assigned to the Wills Ridge, Ashe, and Alligator

  16. Cleavage Luminescence from Cleaved Indium Phosphide

    International Nuclear Information System (INIS)

    Dong-Guang, Li

    2008-01-01

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

  17. [Synthesis of reserve polyhydroxyalkanoates by luminescent bacteria].

    Science.gov (United States)

    Boiandin, A N; Kalacheva, G S; Rodicheva, E K; Volova, T G

    2008-01-01

    The ability of marine luminescent bacteria to synthesize polyesters of hydroxycarboxylic acids (polyhydroxyalkanoates, PHA) as reserve macromolecules was studied. Twenty strains from the collection of the luminescent bacteria CCIBSO (WDSM839) of the Institute of Biophysics, Siberian Branch, Russian Academy of Sciences, assigned to different taxa (Photobacterium leiognathi, Ph. phosphoreum, Vibrio harveyi, and V. fischeri) were analyzed. The most productive strains were identified, and the conditions ensuring high polymer yields in batch culture (40-70% of the cell dry mass weight) were determined. The capacity of synthesizing two- and three-component polymers containing hydroxybutyric acid as the main monomer and hydroxyvaleric and hydroxyhexanoic acids was revealed in Ph. leiognathi and V. harveyi strains. The results allow luminescent microorganisms to be regarded as new producers of multicomponent polyhydroxyalkanoates.

  18. Sub-ppb level detection of uranium using ligand sensitized luminescence

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  19. Luminescent lanthanide coordination polymers

    Energy Technology Data Exchange (ETDEWEB)

    Ma, L.; Evans, O.R.; Foxman, B.M.; Lin, W.

    1999-12-13

    One-dimensional lanthanide coordination polymers with the formula Ln(isonicotinate){sub 3}(H{sub 2}O){sub 2} (Ln = Ce, Pr, Nd, Sm, Eu, Tb; 1a-f) were synthesized by treating nitrate or perchlorate salts of Ln(III) with 4-pyridinecarboxaldehyde under hydro(solvo)thermal conditions. Single-crystal and powder X-ray diffraction studies indicate that these lanthanide coordination polymers adopt two different structures. While Ce(III), Pr(III), and Nd(III) complexes adopt a chain structure with alternating Ln-(carboxylate){sub 2}-Ln and Ln-(carboxylate){sub 4}-Ln linkages, Sm(III), Eu(III), and Tb(III) complexes have a doubly carboxylate-bridged infinite-chain structure with one chelating carboxylate group on each metal center. In both structures, the lanthanide centers also bind to two water molecules to yield an eight-coordinate, square antiprismatic geometry. The pyridine nitrogen atoms of the isonicotinate groups do not coordinate to the metal centers in these lanthanide(III) complexes; instead, they direct the formation of Ln(III) coordination polymers via hydrogen bonding with coordinated water molecules. Photoluminescence measurements show that Tb(isonicotinate){sub 3}(H{sub 2}O){sub 2} is highly emissive at room temperature with a quantum yield of {approximately}90%. These results indicate that highly luminescent lanthanide coordination polymers can be assembled using a combination of coordination and hydrogen bonds. Crystal data for 1a: monoclinic space group P2{sub 1}/c, a = 9.712(2) {angstrom}, b = 19.833(4) {angstrom}, c = 11.616(2) {angstrom}, {beta} = 111.89(3){degree}, Z = 4. Crystal data for 1f: monoclinic space group C2/c, a = 20.253(4) {angstrom}, b = 11.584(2) {angstrom}, c = 9.839(2) {angstrom}, {beta} = 115.64(3){degree}, Z = 8.

  20. Pyridine substituted spirofluorene derivative as an electron transport material for high efficiency in blue organic light-emitting diodes

    Energy Technology Data Exchange (ETDEWEB)

    Jeon, Soon Ok; Yook, Kyoung Soo; Lee, Jun Yeob, E-mail: leej17@dankook.ac.k

    2010-11-01

    The quantum efficiency of blue fluorescent organic light-emitting diodes was enhanced by 20% using a pyridine substituted spirofluorene-benzofluorene derivative as an electron transport material. 2',7'-Di(pyridin-3-yl)spiro[benzofluorene-7,9'-fluorene] (SPBP) was synthesized and it was used as the electron transport material to block the hole leakage from the emitting layer. The improvement of the quantum efficiency and power efficiency of the blue fluorescent organic light-emitting diodes using the SPBP was investigated.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2004-06-01

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

  2. Luminescence study of spodumene

    International Nuclear Information System (INIS)

    Isotani, S.; Fujii, A.T.; Antonini, R.; Pontuschka, W.M.; Rabani, S.R.; Furtado, W.W.

    1990-02-01

    A comparative study is made of the luminescence of five kinds of spodumene from Minas Gerais, Brazil, studied previously by optical absorption spectroscopy. Natural gemstones are used which, in the course of the experiments, were irradiated with X-rays. (L.C.) [pt

  3. Silicon: electrochemistry and luminescence

    NARCIS (Netherlands)

    Kooij, Ernst Stefan

    1997-01-01

    The electrochemistry of crystalline and porous silicon and the luminescence from porous silicon has been studied. One chapter deals with a model for the anodic dissolution of silicon in HF solution. In following chapters both the electrochemistry and various ways of generating visible

  4. Three luminescent d{sup 10} metal coordination polymers assembled from a semirigid V-shaped ligand with high selective detecting of Cu{sup 2+} ion and nitrobenzene

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Wei-Ping [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorg. Chem., College of Chemistry & Materials Science, Northwest University, Xi’an 710069 (China); Institute of Functional Materials, College of Chemistry and Pharmaceutical Engineering, Sichuan University of Science & Engineering, Zigong 643000 (China); Liu, Ping; Liang, Yu-Tong; Cui, Lin; Xi, Zheng-Ping [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorg. Chem., College of Chemistry & Materials Science, Northwest University, Xi’an 710069 (China); Wang, Yao-Yu, E-mail: wyaoyu@nwu.edu.cn [Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education, Shaanxi Key Laboratory of Physico-Inorg. Chem., College of Chemistry & Materials Science, Northwest University, Xi’an 710069 (China)

    2015-08-15

    Three 2D luminescent coordination polymers with helical frameworks, [ZnL{sub 2}]{sub n} (1) and ([ML{sub 2}]·(H{sub 2}O)){sub n} (M=Zn (2), Cd (3)) (HL=4-((2-methyl-1 H-imidazol-1-yl)methyl)benzoic acid), have been assembled under hydro(solvo)thermal conditions. Complex 1 is in chiral space group and displays a rare 2D→2D 2-fold parallel interpenetrated layer network with two types of chiral double helixes. Interestingly, the single crystal structure analyses indicate the coexistence of enantiomers la and 1b in one pot, while the bulk crystallization of 1 are racemic mixtures based on the CD measurement. 2 and 3 are isostructural, in the structure, there are two kinds of 2D chiral helical-layers which stack in an -ABAB- sequence leading to the overall structure are mesomer and achiral. All compounds display intense luminescence in solid state at room temperature with high chemical and thermal stability. More importantly, 1 has been successfully applied in the detection of Cu{sup 2+} ions in aqueous media and nitrobenzene and the probable detecting mechanism was also discussed. - Graphical abstract: Three luminescent d{sup 10} metal coordination polymers with helical-layer based on 4-((2-methyl-1H-imidazol-1-yl)methyl)benzoic acid have been obtained. Compound 1 shows high selective detecting for Cu{sup 2+} ion in aqueous and nitrobenzene. - Highlights: • Three coordination polymers with chiral helical-layer have been obtained. • 1 Can luminescent detect Cu{sup 2+} ion in aqueous media and nitrobenzene. • Racemic mixture or mesomer compounds can be obtained by controlling the reaction conditions.

  5. The high cost of fine print. Antitrust case against a major Blue Cross plan may redefine terms of contract negotiations.

    Science.gov (United States)

    Evans, Melanie; Blesch, Gregg

    2010-10-25

    With its challenge to Michigan Blues contracts with some hospitals, the Justice Department is doing something it hasn't in more than 10 years. The move means insurers need to carefully vet contracts for similar issues. "This signals they're still in the enforcement business as it relates to healthcare insurance," says lawyer David Marx Jr.

  6. Piezoelectrically-induced stress-luminescence phenomenon in CaAl2O4:Eu2+

    International Nuclear Information System (INIS)

    Wei, Yongbin; Wu, Zheng; Jia, Yanmin; Liu, Yongsheng

    2015-01-01

    Piezoelectrically-induced stress-luminescence in the CaAl 2 O 4 :Eu 2+ was investigated. Blue light that was visible to the naked eye could be observed in the dark when a pulse force of ∼7.7 kN was applied to the sample. The intensity of the stress-luminescence strongly depended on the magnitude of the applied force during a pulse cycle. The intensity decreased with repetitive application of pulse stress and was completely recovered after irradiation with ultraviolet light. It is suggested that the stress-luminescence effect in CaAl 2 O 4 :Eu 2+ arises from the piezoelectrically-induced de-trapping of the charge carriers. A CaAl 2 O 4 :Eu 2+ ceramic that exhibits a stress-luminescence effect has potential applications in smart stress optically-sensing devices. - Highlights: • The strong induced stress-luminescence in CaAl 2 O 4 :Eu 2+ was observed. • The stress-luminescent intensity strongly depends on the magnitude of force. • The stress-luminescence could be completely recovered after the UV irradiation. • The strong stress-luminescent effect is potential in stress-light sensors

  7. China Mobile: Expanding "Blue Ocean"

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    Driving force is crucial for realizing high-speed growth. The strong driving force from "Blue Ocean Strategy" is an important advantage for China Mobile to realize harmonious and leap-forward development.

  8. From plasmon-induced luminescence enhancement in gold nanorods to plasmon-induced luminescence turn-off: a way to control reshaping.

    Science.gov (United States)

    Molinaro, Céline; Marguet, Sylvie; Douillard, Ludovic; Charra, Fabrice; Fiorini-Debuisschert, Céline

    2018-04-24

    Two-photon luminescence (TPL) turn-off in small single gold nanorods (GNRs) exposed to increased resonant femtosecond laser excitation (800 nm wavelength, pulse energy density varying from 125 μJ cm-2 to 2.5 mJ cm-2) is investigated. The origin is shown to be a photo-induced decrease of the rod aspect ratio. This aspect ratio reduction could reasonably be assigned to gold atom diffusion away from the rod tips, where hot spots are localized. The two-photon luminescence signal can be recovered after a blue-shift of the incident excitation wavelength. No change in the excitation wavelength results in an out of resonance excitation of the rods and thus a reduced absorption, acting as feedback to stabilize the GNR shape and size. A theoretical analysis is presented evidencing limited thermal effects in the femtosecond regime for small nanoparticles, in good agreement with complementary topographic characterizations using scanning electron microscopy (SEM) and atomic force microscopy (AFM). We show finally that TPL reveals itself as a highly sensitive tool to follow tiny changes resulting from the photo-induced reshaping of GNRs.

  9. Effect of structure, size and copper doping on the luminescence properties of ZnS

    Energy Technology Data Exchange (ETDEWEB)

    Kamal, Ch. Satya [Crystal Growth and Nanoscience Research Centre, Government College (A), Rajahmundry, Andhra Pradesh 533 105 (India); Mishra, R.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Patel, Dinesh K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Casali Center for Applied Chemistry, The Hebrew University of Jerusalem, 9190401 (Israel); Rao, K. Ramachandra, E-mail: drkrcr@gmail.com [Crystal Growth and Nanoscience Research Centre, Government College (A), Rajahmundry, Andhra Pradesh 533 105 (India); Sudarsan, V., E-mail: vsudar@barc.gov.in [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India); Vatsa, R.K. [Chemistry Division, Bhabha Atomic Research Centre, Mumbai 400085 (India)

    2016-09-15

    Highlights: • Blue and green emission intensity form ZnS is sensitive to crystallographic form. • For ZnS nanoparticles, emission characteristics are not affected by copper doping. • Cu solubility poor in ZnS nanoparticles compared to corresponding bulk. - Abstract: Luminescence properties of wurtzite and cubic forms of bulk ZnS have been investigated in detail and compared with that of ZnS nanoparticles. Blue emission observed in both hexagonal and cubic forms of undoped bulk ZnS is explained based on electron–hole recombination involving electron in conduction band and hole trapped in Zn{sup 2+} vacancies where as green emission arises due to electron hole recombination from Zn{sup 2+} and S{sup 2−} vacancies. Conversion of wurtzite form to cubic form is associated with relative increase in intensity of green emission due to increased defect concentration brought about by high temperature heat treatment. Copper doping in ZnS, initially leads to formation of both Cu{sub Zn} and Cu{sub i} (interstitial copper) centers, and latter to mainly Cu{sub Zn} centers as revealed by variation in relative intensities of blue and green emission from the samples.

  10. Doping-free white organic light-emitting diodes without blue molecular emitter: An unexplored approach to achieve high performance via exciplex emission

    Science.gov (United States)

    Luo, Dongxiang; Xiao, Ye; Hao, Mingming; Zhao, Yu; Yang, Yibin; Gao, Yuan; Liu, Baiquan

    2017-02-01

    Doping-free white organic light-emitting diodes (DF-WOLEDs) are promising for the low-cost commercialization because of their simplified device structures. However, DF-WOLEDs reported thus far in the literature are based on the use of blue single molecular emitters, whose processing can represent a crucial point in device manufacture. Herein, DF-WOLEDs without the blue single molecular emitter have been demonstrated by managing a blue exciplex system. For the single-molecular-emitter (orange or yellow emitter) DF-WOLEDs, (i) a color rendering index (CRI) of 81 at 1000 cd/m2 can be obtained, which is one of the highest for the single-molecular-emitter WOLEDs, or (ii) a high efficiency of 35.4 lm/W can be yielded. For the dual-molecular-emitter (yellow/red emitters) DF-WOLED, a high CRI of 85 and low correlated color temperature of 2376 K at 1000 cd/m2 have been simultaneously achieved, which has not been reported by previous DF-WOLEDs. Such presented findings may unlock an alternative avenue to the simplified but high-performance WOLEDs.

  11. Effect of Al/Ga substitution on the structural and luminescence properties of Y3(Al1-xGax)5O12: Ce3+ phosphors

    Science.gov (United States)

    Fu, Sheng; Tan, Jin; Bai, Xin; Yang, Shanjie; You, Lei; Du, Zhengkang

    2018-01-01

    As candidates for display and lighting materials, a series of gallium-substituted cerium-doped yttrium aluminum garnet (Y3(GaxAl1-x)5O12: Ce3+) phosphors were synthesized by high temperature solid-state reaction. The phases, morphology, luminescence spectra and thermal stability of the phosphors were investigated. The volatilization of Ga2O3 induces the constituents out of stoichiometric ratio and different impurities in the system. The excitation and emission spectra occur red shift (339 nm - 351 nm) and blue shift (465 nm - 437 nm), and blue shift (541 nm - 517 nm), respectively. The spectra have no further blue shift and the luminescence intensity decrease with x over 0.4. Combining crystal structure with PL spectrum, the distortion of dodecahedron and crystal field splitting of 5d level of Ce3+ are influenced by Ga3+ in octahedral coordination polyhedron rather than tetrahedron. The crystalline perfection and Ga3+ occupying the tetrahedron induce less garnet phase formation, more impurities and the 5d level located in the conductive bands, thus accounting for the x = 0.4 turning points of the PL and PLE intensity. Based on the thermal quenching and CIE, the Y3(GaxAl1-x)5O12: Ce3+0.06 phosphors have great potential for use on the w-LED.

  12. High-efficiency pyrene-based blue light emitting diodes: Aggregation suppression using a calixarene 3D-scaffold

    KAUST Repository

    Chan, Khaileok

    2012-01-01

    An efficient blue light emitting diode based on solution processable pyrene-1,3-alt-calix[4]arene is demonstrated, providing a record current efficiency of 10.5 cd A -1 in a simple non-doped OLED configuration. Complete suppression of pyrene aggregation in the solid state is achieved by controlling chromophore dispersion using the 1,3-alt-calix[4]arene scaffold. © 2012 The Royal Society of Chemistry.

  13. A highly conspicuous mineralized composite photonic architecture in the translucent shell of the blue-rayed limpet

    OpenAIRE

    Li, Ling; Kolle, Stefan; Weaver, James C.; Ortiz, Christine; Aizenberg, Joanna; Kolle, Mathias

    2015-01-01

    Many species rely on diverse selections of entirely organic photonic structures for the manipulation of light and the display of striking colours. Here we report the discovery of a mineralized hierarchical photonic architecture embedded within the translucent shell of the blue-rayed limpet Patella pellucida. The bright colour of the limpet’s stripes originates from light interference in a periodically layered zig-zag architecture of crystallographically co-oriented calcite lamellae. Beneath t...

  14. A Novel Approach to Synthesise a Dual-Mode Luminescent Composite Pigment for Uncloneable High-Security Codes to Combat Counterfeiting.

    Science.gov (United States)

    Kanika; Kumar, Pawan; Singh, Satbir; Gupta, Bipin Kumar

    2017-12-01

    A strategy is demonstrated to protect valuable items, such as currency, pharmaceuticals, important documents, etc. against counterfeiting, by marking them with luminescent security codes. These luminescent security codes were printed by employing luminescent ink formulated from a cost effective dual-mode luminescent composite pigment of Gd 1.7 Yb 0.2 Er 0.1 O 3 and Zn 0.98 Mn 0.02 S phosphors using commercially available PVC Gold medium. In the composite, Gd 1.7 Yb 0.2 Er 0.1 O 3 and Zn 0.98 Mn 0.02 S account for upconversion and downconversion processes, respectively. The synthesis procedure of the composite involves the admixing of Gd 1.7 Yb 0.2 Er 0.1 O 3 nanorods and Zn 0.98 Mn 0.02 S phosphor, synthesised by hydrothermal and facile solid-state reaction methods, respectively. The structural, morphological, microstructural, and photoluminescent features of Gd 1.7 Yb 0.2 Er 0.1 O 3 nanorods, Zn 0.98 Mn 0.02 S phosphor and composite were characterised by using XRD, SEM, TEM, and photoluminescence (PL) techniques, respectively. The distribution of PL intensity of the printed pattern was examined by using confocal PL mapping microscopy. The obtained results reveal that security codes printed using ink formulated from this bi-luminescent composite pigment provide dual-stage security against counterfeiting. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Hydrothermal synthesis of polyethylenimine-protected high luminescent Pt-nanoclusters and their application to the detection of nitroimidazoles

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Na [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China); College of Materials Science and Engineering, Jilin Institute of Chemical Technology, Jilin, 132022 (China); Li, Hong-Wei, E-mail: lihongwei@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China); Wu, Yuqing, E-mail: yqwu@jlu.edu.cn [State Key Laboratory of Supramolecular Structure and Materials, College of Chemistry, Jilin University, Changchun, 130012 (China)

    2017-03-15

    A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths, and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body. - Highlights: • This paper provides the first hydrothermal synthesis of platinum nanoclusters. • The prepared polyethylenimine-protected platinum nanoclusters possess high quantum yield of 28%. • A new method to detect trace amount of metronidazole in urine is proposed.

  16. Hydrothermal synthesis of polyethylenimine-protected high luminescent Pt-nanoclusters and their application to the detection of nitroimidazoles

    International Nuclear Information System (INIS)

    Xu, Na; Li, Hong-Wei; Wu, Yuqing

    2017-01-01

    A novel one-step hydrothermal synthesis of highly fluorescent platinum nanoclusters protected by polyethylenimine (Pt-NCs@PEI) is described. The products are characterized well by UV–vis absorption, fluorescence spectra, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM) imaging. The Pt-NCs@PEI possess high quantum yield at 28%, which is the relatively high one among the reported Pt-NCs; especially, the synthesis is in one-step and the reaction time is much shorter (<1 h) than the related methods. In addition, the Pt-NCs@PEI have large Stocks-shift (∼150 nm), high tolerability to the extreme pH and high ionic strengths, and excellent photo-stability under UV–vis irradiation, lay the foundation for the practical bio-applications. Finally, the obtained Pt-NCs@PEI are used to determine trace amount of metronidazole (MTZ) in buffer solution in showing a linear response over a concentration range of 0.25–300 μM and a low detection limit of 0.1 μM. Furthermore, the related investigation on response mechanism will be helpful to design and synthesize new metal nanoclusters as fluorescent probe to detect the trace amount of harmful medicine residuum as nitroimidazoles in human body. - Highlights: • This paper provides the first hydrothermal synthesis of platinum nanoclusters. • The prepared polyethylenimine-protected platinum nanoclusters possess high quantum yield of 28%. • A new method to detect trace amount of metronidazole in urine is proposed.

  17. Splitting of the luminescent excited state of the uranyl ion

    International Nuclear Information System (INIS)

    Flint, C.D.; Sharma, P.; Tanner, P.A.

    1982-01-01

    The luminescence spectra of some uranyl compounds has been studied. It has been proposed that the splitting of the luminescent excited state of the uranyl ion is due to a descent in symmetry experienced by the uranyl ion when it is placed in a crystal field. In recent years there has been developed a highly successful model of the electronic structure of the uranyl ion. In this paper the authors use this model to interpret the luminescence spectra of a variety of uranyl compounds

  18. Luminescent solar concentrator

    Directory of Open Access Journals (Sweden)

    Tugce Tosun

    2015-07-01

    Full Text Available Luminescent solar concentrator (LSC is a device that has luminescent molecules embedding or topping polymeric or glass waveguide to generate electricity from sunlight with a photovoltaic cell attachment. LSCs can be employed both in small and large scale projects, independent on the direction or angle of the surface with respect to the sun, promising more freedom for integration in urban environments compared to the traditional PV systems. The aim of the SEB&C PDEng project is to investigate the applicability of this innovative technology in the built environment and to bridge the gap of knowledge linking societal, design and technological aspects. The final goal is to exhibit potential application concepts of LSC developed by co-creative methods at SPARK campus which is a hub for open innovation in built environment. Necessity of a paradigm shift towards sustainable and smart cities came into being due to the significant increase in energy demand of the buildings. The challenge is to increase renewable sources in the energy mix while designing aesthetic environments. Thus, building integrated renewable energy technologies represent a great opportunity to help overcome this current challenge. Smart energy, energy efficiency and use of renewable sources are key aspects to be considered nowadays and many innovative technologies need further exploitation to be commercially viable, such as luminescent solar concentrator.

  19. Quantitative luminescence imaging system

    Science.gov (United States)

    Erwin, David N.; Kiel, Johnathan L.; Batishko, Charles R.; Stahl, Kurt A.

    1990-01-01

    The QLIS images and quantifies low-level chemiluminescent reactions in an electromagnetic field. It is capable of real time nonperturbing measurement and simultaneous recording of many biochemical and chemical reactions such as luminescent immunoassays or enzyme assays. The system comprises image transfer optics, a low-light level digitizing camera with image intensifying microchannel plates, an image process or, and a control computer. The image transfer optics may be a fiber image guide with a bend, or a microscope, to take the light outside of the RF field. Output of the camera is transformed into a localized rate of cumulative digitalized data or enhanced video display or hard-copy images. The system may be used as a luminescent microdosimetry device for radiofrequency or microwave radiation, as a thermal dosimeter, or in the dosimetry of ultra-sound (sonoluminescence) or ionizing radiation. It provides a near-real-time system capable of measuring the extremely low light levels from luminescent reactions in electromagnetic fields in the areas of chemiluminescence assays and thermal microdosimetry, and is capable of near-real-time imaging of the sample to allow spatial distribution analysis of the reaction. It can be used to instrument three distinctly different irradiation configurations, comprising (1) RF waveguide irradiation of a small Petri-dish-shaped sample cell, (2) RF irradiation of samples in a microscope for the microscopie imaging and measurement, and (3) RF irradiation of small to human body-sized samples in an anechoic chamber.

  20. Bright upconversion luminescence and increased Tc in CaBi2Ta2O9:Er high temperature piezoelectric ceramics

    International Nuclear Information System (INIS)

    Peng Dengfeng; Wang Xusheng; Yao Xi; Xu Chaonan; Lin Jian; Sun Tiantuo

    2012-01-01

    Er 3+ doped CaBi 2 Ta 2 O 9 (CBT) bismuth layered-structure high temperature piezoelectric ceramics were synthesized by the traditional solid state method. The upconversion (UC) emission properties of Er 3+ doped CBT ceramics were investigated as a function of Er 3+ concentration and incident pump power. A bright green upconverted emission was obtained under excitation 980 nm at room temperature. The observed strong green and weak red emission bands corresponded to the transitions from 4 S 3/2 and 4 F 9/2 to 4 I 15/2 , respectively. The dependence of UC emission intensity on pumping power indicated that a three-photon process was involved in UC emissions. Studies of dielectric with temperature have also been carried out. Introduction of Er increased the Curie temperature of CBT, thus, making this ceramic suitable for sensor applications at higher temperatures. Because of its strong up-converted emission and increased Tc, the multifunctional high temperature piezoelectric ceramic may be useful in high temperature sensor, fluorescence thermometry, and optical-electro integration applications.

  1. Holographic patterning of luminescent photopolymer nanocomposites

    International Nuclear Information System (INIS)

    Sakhno, Oksana V.; Smirnova, Tatiana N.; Goldenberg, Leonid M.; Stumpe, Joachim

    2008-01-01

    Volume phase gratings in the photopolymerisable composites, containing luminescent nanoparticles have been fabricated for the first time. Nanoparticles of LaPO 4 , doped by Ce 3+ and Tb 3+ ions (the trade name is REN-X-green) with high luminescence quantum yield were used as a luminescent inorganic additive. The holographic gratings in such materials are formed as a result of the diffusion distribution of the nanoparticles during exposure of photopolymerisable composites to interference pattern. The influence of the pre-polymer formulation and the holographic patterning parameters on the grating formation is comprehensively investigated. The use of the optimised pre-polymer syrup containing two monomers with sufficiently different polymerisation rates allows fabrication of gratings with diffraction efficiency up to 80% at low optical losses (< 5%) (20 μm film thickness). To obtain maximum diffraction efficiency the intensity and the period of the interference pattern were optimised for each formulation. In addition maximum diffraction efficiency was achieved with the nanocomposites containing 30-32 wt.% of nanoparticles. On the other hand the highest possible modulation of the nanoparticles' concentration was obtained for the concentration of about 20 wt.%. In this case maximum ordering of the nanoparticles in the polymer matrix is achieved. The photoluminescence of the nanoparticles within the homogeneous polymer film and within the grating has been measured. The example application of the photopolymerisable composite containing luminescence inorganic nanoparticles in holographic security technology has been demonstrated

  2. Luminescent passive-oxidized silicon quantum dots as biological staining labels and their cytotoxicity effects at high concentration

    International Nuclear Information System (INIS)

    Fujioka, Kouki; Manabe, Noriyoshi; Hanada, Sanshiro; Hoshino, Akiyoshi; Yamamoto, Kenji; Hiruoka, Masaki; Sato, Keisuke; Hirakuri, Kenji; Miyasaka, Ryosuke; Tilley, Richard D; Manome, Yoshinobu

    2008-01-01

    Semiconductor quantum dots (QDs) hold some advantages over conventional organic fluorescent dyes. Due to these advantages, they are becoming increasingly popular in the field of bioimaging. However, recent work suggests that cadmium based QDs affect cellular activity. As a substitute for cadmium based QDs, we have developed photoluminescent stable silicon quantum dots (Si-QDs) with a passive-oxidation technique. Si-QDs (size: 6.5 ± 1.5 nm) emit green light, and they have been used as biological labels for living cell imaging. In order to determine the minimum concentration for cytotoxicity, we investigated the response of HeLa cells. We have shown that the toxicity of Si-QDs was not observed at 112 μg ml -1 and that Si-QDs were less toxic than CdSe-QDs at high concentration in mitochondrial assays and with lactate dehydrogenase (LDH) assays. Especially under UV exposure, Si-QDs were more than ten times safer than CdSe-QDs. We suggest that one mechanism for the cytotoxicity is that Si-QDs can generate oxygen radicals and these radicals are associated with membrane damages. This work has demonstrated the suitability of Si-QDs for bioimaging in lower concentration, and their cytotoxicity and one toxicity mechanism at high concentration

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

    Energy Technology Data Exchange (ETDEWEB)

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

    2015-04-01

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

  4. Facile and high spatial resolution ratio-metric luminescence thermal mapping in microfluidics by near infrared excited upconversion nanoparticles

    International Nuclear Information System (INIS)

    Wang, Yu; Li, Shunbo; Wen, Weijia; Cao, Wenbin

    2016-01-01

    A local area temperature monitor is important for precise control of chemical and biological processes in microfluidics. In this work, we developed a facile method to realize micron spatial resolution of temperature mapping in a microfluidic channel quickly and cost effectively. Based on the temperature dependent fluorescence emission of NaYF 4 :Yb 3+ , Er 3+ upconversion nanoparticles (UCNPs) under near-infrared irradiation, ratio-metric imaging of UCNPs doped polydimethylsiloxane can map detailed temperature distribution in the channel. Unlike some reported strategies that utilize temperature sensitive organic dye (such as Rhodamine) to achieve thermal sensing, our method is highly chemically inert and physically stable without any performance degradation in long term operation. Moreover, this method can be easily scaled up or down, since the spatial and temperature resolution is determined by an optical imaging system. Our method supplied a simple and efficient solution for temperature mapping on a heterogeneous surface where usage of an infrared thermal camera was limited

  5. Development of optically stimulated luminescence reader systems in BARC

    International Nuclear Information System (INIS)

    Kulkarni, M.S.

    2008-01-01

    BARC has very vast experience in the development of thermoluminescence (TL) reader systems both for routine personnel monitoring and research application. However, optically stimulated luminescence (OSL) related instrumentation is a recent development in BARC. The increasing popularity of OSL technique in the radiation dosimetry applications in the recent past has driven investigation and developmental programme in the OSL measurement facilities at BARC. As the consequence of the efforts directed towards the indigenous development of OSL reader system, OSL readers with various readout modes like continuous wave (CW) OSL mode, linear intensity modulated OSL (LM-OSL), pulsed OSL (POSL) have been developed. In addition to these conventional modes of operation a novel non-linear OSL mode (NL-OSL) has also been developed for the OSL measurements. This paper reviews the details of the development of OSL reader system including experience with high intensity blue/green LED stimulation light source and detection system. Also discussed are recently developed versatile integrated TL/OSL reader systems for TL and OSL measurements. (author)

  6. Ion beam induced luminescence from diamond using an MeV ion microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Bettiol, A A; Jamieson, D N; Prawer, S; Allen, M G [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1994-12-31

    Analysis of the luminescence induced by a MeV ion beam offers the potential to provide useful information about the chemical properties of atoms in crystals to complement the information provided by more traditional Ion Beam Analysis (IBA) such as Rutherford Backscattering Spectrometry (RBS), ion channeling and Particle Induced X-ray Emission (PIXE). Furthermore, the large penetration depth of the MeV ion beam offers several advantages over the relatively shallow penetration of keV electrons typically employed in cathodoluminescence. An Ion Beam Induced Luminescence (IBIL) detection system was developed for the Melbourne microprobe that allows the spatial mapping of the luminescence signal along with the signals from RBS and PIXE. Homoepitaxial diamond growth has been studied and remarkable shifts in the characteristic blue luminescence of diamond towards the green were observed in the overgrowth. This has been tentatively identified as being due to transition metal inclusions in the epitaxial layers. 8 refs., 2 refs.

  7. Ion beam induced luminescence from diamond using an MeV ion microprobe

    Energy Technology Data Exchange (ETDEWEB)

    Bettiol, A.A.; Jamieson, D. N.; Prawer, S.; Allen, M.G. [Melbourne Univ., Parkville, VIC (Australia). School of Physics

    1993-12-31

    Analysis of the luminescence induced by a MeV ion beam offers the potential to provide useful information about the chemical properties of atoms in crystals to complement the information provided by more traditional Ion Beam Analysis (IBA) such as Rutherford Backscattering Spectrometry (RBS), ion channeling and Particle Induced X-ray Emission (PIXE). Furthermore, the large penetration depth of the MeV ion beam offers several advantages over the relatively shallow penetration of keV electrons typically employed in cathodoluminescence. An Ion Beam Induced Luminescence (IBIL) detection system was developed for the Melbourne microprobe that allows the spatial mapping of the luminescence signal along with the signals from RBS and PIXE. Homoepitaxial diamond growth has been studied and remarkable shifts in the characteristic blue luminescence of diamond towards the green were observed in the overgrowth. This has been tentatively identified as being due to transition metal inclusions in the epitaxial layers. 8 refs., 2 refs.

  8. Luminescence imaging of water during alpha particle irradiation

    Science.gov (United States)

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

    2016-05-01

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

  9. Luminescence imaging of water during alpha particle irradiation

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-05-21

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

  10. Facile and high spatial resolution ratio-metric luminescence thermal mapping in microfluidics by near infrared excited upconversion nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Yu; Li, Shunbo; Wen, Weijia, E-mail: phwen@ust.hk [Department of Physics, KAUST-HKUST Joint Micro/Nanofluidic Laboratory, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Cao, Wenbin [Nano Science and Technology Program, Department of Physics, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong)

    2016-02-01

    A local area temperature monitor is important for precise control of chemical and biological processes in microfluidics. In this work, we developed a facile method to realize micron spatial resolution of temperature mapping in a microfluidic channel quickly and cost effectively. Based on the temperature dependent fluorescence emission of NaYF{sub 4}:Yb{sup 3+}, Er{sup 3+} upconversion nanoparticles (UCNPs) under near-infrared irradiation, ratio-metric imaging of UCNPs doped polydimethylsiloxane can map detailed temperature distribution in the channel. Unlike some reported strategies that utilize temperature sensitive organic dye (such as Rhodamine) to achieve thermal sensing, our method is highly chemically inert and physically stable without any performance degradation in long term operation. Moreover, this method can be easily scaled up or down, since the spatial and temperature resolution is determined by an optical imaging system. Our method supplied a simple and efficient solution for temperature mapping on a heterogeneous surface where usage of an infrared thermal camera was limited.

  11. Selective high capacity adsorption of Congo red, luminescence and antibacterial assessment of two new cadmium(II) coordination polymers

    Science.gov (United States)

    Beheshti, Azizolla; Nozarian, Kimia; Ghamari, Narges; Mayer, Peter; Motamedi, Hossein

    2018-02-01

    Coordination polymers [CdCl(NCS)L]n (1) and {[Cd2I4(L)2]·H2O·DMF}n (2) (where L = 1, 1-(1,4-butanediyl)bis(1,3-dihydro-3-methyl-1H-imidazole- 2-thione)) were synthesized and structurally characterized. Compounds 1 and 2 both possess a tetrahedral arrangement with CdS2NCl and CdS2I2 cores, respectively. In these structures, the flexible thione ligands adopt a μ- bridging coordination mode to form 1D chains along the b-axis. The 1D chains are join together by C-H--Cl hydrogen bonds (in 1) and water molecules (in 2) to create a 2D supramolecular framework with an ABAB…packing mode. Remarkably, compounds 1 and 2 in particular polymer 1 exhibit excellent capacity to adsorb Congo red (CR) with high selectivity. The experimental data demonstrate that the mechanism of sorption process can be described by the Elovich and pseudo second order kinetic models for 1 and 2, respectively. Furthermore, the possible mechanism of CR absorption was investigated by UV-Vis and solid state fluorescence spectra for the title polymers. In addition, the antibacterial assessment of these compounds have also been studied.

  12. Luminescent zinc(ii) and copper(i) complexes for high-performance solution-processed monochromic and white organic light-emitting devices† †Electronic supplementary information (ESI) available: Experimental procedures, device performances, and computational details. CCDC 1054456, 1400003 and 1400004. For ESI and crystallographic data in CIF or other electronic format see DOI: 10.1039/c4sc03161j Click here for additional data file. Click here for additional data file.

    Science.gov (United States)

    Cheng, Gang; So, Gary Kwok-Ming; To, Wai-Pong; Chen, Yong; Kwok, Chi-Chung; Ma, Chensheng; Guan, Xiangguo; Chang, Xiaoyong; Kwok, Wai-Ming

    2015-01-01

    The synthesis and spectroscopic properties of luminescent tetranuclear zinc(ii) complexes of substituted 7-azaindoles and a series of luminescent copper(i) complexes containing 7,8-bis(diphenylphosphino)-7,8-dicarba-nido-undecaborate ligand are described. These complexes are stable towards air and moisture. Thin film samples of the luminescent copper(i) complexes in 2,6-dicarbazolo-1,5-pyridine and zinc(ii) complexes in poly(methyl methacrylate) showed emission quantum yields of up to 0.60 (for Cu-3) and 0.96 (for Zn-1), respectively. Their photophysical properties were examined by ultrafast time-resolved emission spectroscopy, temperature dependent emission lifetime measurements and density functional theory calculations. Monochromic blue and orange solution-processed OLEDs with these Zn(ii) and Cu(i) complexes as light-emitting dopants have been fabricated, respectively. Maximum external quantum efficiency (EQE) of 5.55% and Commission Internationale de l'Eclairage (CIE) coordinates of (0.16, 0.19) were accomplished with the optimized Zn-1-OLED while these values were, respectively 15.64% and (0.48, 0.51) for the optimized Cu-3-OLED. Solution-processed white OLEDs having maximum EQE of 6.88%, CIE coordinates of (0.42, 0.44), and colour rendering index of 81 were fabricated by using these luminescent Zn(ii) and Cu(i) complexes as blue and orange light-emitting dopant materials, respectively. PMID:29142704

  13. Synthesis and highly visible-induced photocatalytic activity of CNT-CdSe composite for methylene blue solution

    Directory of Open Access Journals (Sweden)

    Chen Ming-Liang

    2011-01-01

    Full Text Available Abstract Carbon nanotube-cadmium selenide (CNT-CdSe composite was synthesized by a facile hydrothermal method derived from multi-walled carbon nanotubes as a stating material. The as-prepared products were characterized by X-ray diffraction, scanning electron microscopy with energy dispersive X-ray analysis, transmission electron microscopy (TEM, and UV-vis diffuse reflectance spectrophotometer. The as-synthesized CNT-CdSe composite efficiently catalyzed the photodegradation of methylene blue in aqueous solutions under visible-light irradiation, exhibiting higher photocatalytic activity.

  14. Highly efficient and stable white organic light emitting diode base on double recombination zones of phosphorescent blue/orange emitters.

    Science.gov (United States)

    Lee, Seok Jae; Koo, Ja Ryong; Lim, Dong Hwan; Park, Hye Rim; Kim, Young Kwan; Ha, Yunkyoung

    2011-08-01

    We demonstrated efficient and stable white phosphorescent organic light-emitting diodes (OLEDs) with double-emitting layers (D-EMLs), which were comprised of two emissive layers with a hole transport-type host of N,N'-dicarbazolyl-3,5-benzene (mCP) and a electron transport-type host of 2,2',2"-(1,3,5-benzenetryl)tris(1-phenyl)-1H-benzimidazol (TPBi) with blue/orange emitters, respectively. We fabricated two type white devices with single emitting layer (S-EML) and D-EML of orange emitter, maintaining double recombination zone of blue emitter. In addition, the device architecture was developed to confine excitons inside the D-EMLs and to manage triplet excitons by controlling the charge injection. As a result, light-emitting performances of white OLED with D-EMLs were improved and showed the steady CIE coordinates compared to that with S-EML of orange emitter, which demonstrated the maximum luminous efficiency and external quantum efficiency were 21.38 cd/A and 11.09%. It also showed the stable white emission with CIE(x,y) coordinates from (x = 0.36, y = 0.37) at 6 V to (x = 0.33, y = 0.38) at 12 V.

  15. Luminescence dating of Netherland's sediments

    NARCIS (Netherlands)

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

    2007-01-01

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

  16. On the Binary Nature of Massive Blue Hypergiants: High-resolution X-Ray Spectroscopy Suggests That Cyg OB2 12 is a Colliding Wind Binary

    Energy Technology Data Exchange (ETDEWEB)

    Oskinova, L. M.; Hamann, W.-R.; Shenar, T.; Sander, A. A. C.; Todt, H.; Hainich, R. [Institute for Physics and Astronomy, University Potsdam, D-14476 Potsdam (Germany); Huenemoerder, D. P. [Massachusetts Institute of Technology, Kavli Institute for Astrophysics and Space Research, 70 Vassar St., Cambridge, MA 02139 (United States); Ignace, R., E-mail: lida@astro.physik.uni-potsdam.de [Department of Physics and Astronomy, East Tennessee State University, Johnson City, TN 37663 (United States)

    2017-08-10

    The blue hypergiant Cyg OB2 12 (B3Ia{sup +}) is a representative member of the class of very massive stars in a poorly understood evolutionary stage. We obtained its high-resolution X-ray spectrum using the Chandra observatory. PoWR model atmospheres were calculated to provide realistic wind opacities and to establish the wind density structure. We find that collisional de-excitation is the dominant mechanism depopulating the metastable upper levels of the forbidden lines of the He-like ions Si xiv and Mg xii. Comparison between the model and observations reveals that X-ray emission is produced in a dense plasma, which could reside only at the photosphere or in a colliding wind zone between binary components. The observed X-ray spectra are well-fitted by thermal plasma models, with average temperatures in excess of 10 MK. The wind speed in Cyg OB2 12 is not high enough to power such high temperatures, but the collision of two winds in a binary system can be sufficient. We used archival data to investigate the X-ray properties of other blue hypergiants. In general, stars of this class are not detected as X-ray sources. We suggest that our new Chandra observations of Cyg OB2 12 can be best explained if Cyg OB2 12 is a colliding wind binary possessing a late O-type companion. This makes Cyg OB2 12 only the second binary system among the 16 known Galactic hypergiants. This low binary fraction indicates that the blue hypergiants are likely products of massive binary evolution during which they either accreted a significant amount of mass or already merged with their companions.

  17. Development and implementation of a remote audit tool for high dose rate (HDR) Ir-192 brachytherapy using optically stimulated luminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Casey, Kevin E.; Kry, Stephen F.; Howell, Rebecca M.; Followill, David [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 and The University of Texas Graduate School of Biomedical Sciences at Houston, Houston, Texas 77030 (United States); Alvarez, Paola; Lawyer, Ann [Department of Radiation Physics, The University of Texas MD Anderson Cancer Center, Houston, Texas 77030 (United States)

    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

  18. Development and implementation of a remote audit tool for high dose rate (HDR) Ir-192 brachytherapy using optically stimulated luminescence dosimetry

    International Nuclear Information System (INIS)

    Casey, Kevin E.; Kry, Stephen F.; Howell, Rebecca M.; Followill, David; Alvarez, Paola; Lawyer, Ann

    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 cm 3 prototype phantom that had two slots capable of holding Al 2 O 3 :C OSLDs (nanoDots; Landauer, Glenwood, IL) and a single channel capable of accepting all 192 Ir HDR brachytherapy sources in current clinical use in the United States. The authors irradiated the phantom with Nucletron and Varian 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 L = (−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 60 Co irradiation. Separate block correction factors were determined for current versions of both Nucletron and Varian 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 criterion for source strength audits under a

  19. Luminescence from metals and insulators

    International Nuclear Information System (INIS)

    Crawford, O.H.

    1985-01-01

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

  20. A luminescent nisin biosensor

    Science.gov (United States)

    Immonen, Nina; Karp, Matti

    2006-02-01

    Nisin is a lantibiotic, an antibacterial peptide produced by certain Lactococcus lactis strains that kills or inhibits the growth of other bacteria. Nisin is widely used as a food preservative, and its long-time use suggests that it can be generally regarded as safe. We have developed a method for determining the amount of nisin in food samples that is based on luminescent biosensor bacteria. Bacterial luciferase operon luxABCDE was inserted into plasmid pNZ8048, and the construct was transformed by electroporation into Lc. lactis strain NZ9800, whose ability to produce nisin has been erased by deletion of the gene nisA. The operon luxABCDE has been modified to be functional in gram-positive bacteria to confer a bioluminescent phenotype without the requirement of adding an exogenous substrate. In the plasmid pNZ8048, the operon was placed under control of the nisin-inducible nisA promoter. The chromosomal nisRK genes of Lc. lactis NZ9800 allow it to sense nisin in the environment and relay this signal via signal transduction proteins NisK and NisR to initiate transcription from nisA promoter. In the case of our sensor bacteria, this leads to production of luciferase and, thus, luminescence that can be directly measured from living bacteria. Luminescence can be detected as early as within minutes of induction. The nisin assay described here provides a detection limit in the sub-picogram level per ml, and a linear area between 1 - 1000 pg/ml. The sensitivity of this assay exceeds the performance of all previously published methods.

  1. The extended Beer-Lambert theory for ray tracing modeling of LED chip-scaled packaging application with multiple luminescence materials

    Science.gov (United States)

    Yuan, Cadmus C. A.

    2015-12-01

    Optical ray tracing modeling applied Beer-Lambert method in the single luminescence material system to model the white light pattern from blue LED light source. This paper extends such algorithm to a mixed multiple luminescence material system by introducing the equivalent excitation and emission spectrum of individual luminescence materials. The quantum efficiency numbers of individual material and self-absorption of the multiple luminescence material system are considered as well. By this combination, researchers are able to model the luminescence characteristics of LED chip-scaled packaging (CSP), which provides simple process steps and the freedom of the luminescence material geometrical dimension. The method will be first validated by the experimental results. Afterward, a further parametric investigation has been then conducted.

  2. Influence of Nano sized Silicon Oxide on the Luminescent Properties of Zn O Nanoparticles

    International Nuclear Information System (INIS)

    Shvalagin, V.; Grodziuk, G.; Kurmach, M.; Granchak, V.; Sarapulova, O.; Sherstiuk, V.

    2016-01-01

    For practical use of nano sized zinc oxide as the phosphor its luminescence quantum yields should be maximized. The aim of this work was to enhance luminescent properties of Zn O nanoparticles and obtain high-luminescent Zn O/SiO 2 composites using simpler approaches to colloidal synthesis. The luminescence intensity of zinc oxide nanoparticles was increased about 3 times by addition of silica nano crystals to the source solutions during the synthesis of Zn O nanoparticles. Then the quantum yield of luminescence of the obtained Zn O/SiO 2 composites is more than 30%. Such an impact of silica is suggested to be caused by the distribution of Zn O nano crystals on the surface of silica, which reduces the probability of separation of photo generated charges between the zinc oxide nanoparticles of different sizes, and as a consequence, there is a significant increase of the luminescence intensity of Zn O nanoparticles. This way of increasing nano-Zn O luminescence intensity facilitates its use in a variety of devices, including optical ultraviolet and visible screens, luminescent markers, antibacterial coatings, luminescent solar concentrators, luminescent inks for security printing, and food packaging with abilities of informing consumers about the quality and safety of the packaged product.

  3. Influence of Nanosized Silicon Oxide on the Luminescent Properties of ZnO Nanoparticles

    Directory of Open Access Journals (Sweden)

    Vitaliy Shvalagin

    2016-01-01

    Full Text Available For practical use of nanosized zinc oxide as the phosphor its luminescence quantum yields should be maximized. The aim of this work was to enhance luminescent properties of ZnO nanoparticles and obtain high-luminescent ZnO/SiO2 composites using simpler approaches to colloidal synthesis. The luminescence intensity of zinc oxide nanoparticles was increased about 3 times by addition of silica nanocrystals to the source solutions during the synthesis of ZnO nanoparticles. Then the quantum yield of luminescence of the obtained ZnO/SiO2 composites is more than 30%. Such an impact of silica is suggested to be caused by the distribution of ZnO nanocrystals on the surface of silica, which reduces the probability of separation of photogenerated charges between the zinc oxide nanoparticles of different sizes, and as a consequence, there is a significant increase of the luminescence intensity of ZnO nanoparticles. This way of increasing nano-ZnO luminescence intensity facilitates its use in a variety of devices, including optical ultraviolet and visible screens, luminescent markers, antibacterial coatings, luminescent solar concentrators, luminescent inks for security printing, and food packaging with abilities of informing consumers about the quality and safety of the packaged product.

  4. Luminescence quartz dating of lime mortars. A first research approach

    International Nuclear Information System (INIS)

    Zacharias, N.; Mauz, B.; Michael, C.T.

    2002-01-01

    Lime mortars mixed with sand are well suited for connecting structural materials, like stones and bricks, due to the mechanical properties this material exhibits. Their extensive use in architectural and decorative works during the last 4000 years motivated the introduction of the 'Luminescence clock' for age determination of mortars. The same principles as for quartz optically stimulated luminescence (OSL) dating of sediments were applied for age estimation of a mortar fragment removed from a Byzantine church monument dated by archaeological means to 1050-1100 years ago (the first half of the 10th century). The OSL from the quartz was monitored under blue light stimulation and UV detection, using a single-aliquot-regenerative-dose protocol. The quartz-OSL dating of the mortar resulted in 870±230 a. TL polymineral fine grain dating was also performed on a brick fragment which was connected to the mortar, resulting in a TL age of 1095±190 a. (author)

  5. Naturally Efficient Emitters: Luminescent Organometallic Complexes Derived from Natural Products

    Science.gov (United States)

    Zhang, Wen-Hua; Young, David J.

    2013-08-01

    Naturally occurring molecules offer intricate structures and functionality that are the basis of modern medicinal chemistry, but are under-represented in materials science. Herein, we review recent literature describing the use of abundant and relatively inexpensive, natural products for the synthesis of ligands for luminescent organometallic complexes used for organic light emitting diodes (OLEDs) and related technologies. These ligands are prepared from the renewable starting materials caffeine, camphor, pinene and cinchonine and, with the exception of caffeine, impart performance improvements to the emissive metal complexes and resulting OLED devices, with emission wavelengths that span the visible spectrum from blue to red. The advantages of these biologically-derived molecules include improved solution processibility and phase homogeneity, brighter luminescence, higher quantum efficiencies and lower turn-on voltages. While nature has evolved these carbon-skeletons for specific purposes, they also offer some intriguing benefits in materials science and technology.

  6. Highly efficient and simplified phosphorescence white organic light-emitting diodes based on synthesized deep-blue host and orange emitter

    Energy Technology Data Exchange (ETDEWEB)

    Koo, Ja Ryong; Lee, Seok Jae; Hyung, Gun Woo; Kim, Bo Young; Lee, Dong Hyung [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of); Kim, Woo Young [Department of Green Energy and Semiconductor Engineering, Hoseo University, Asan 336-795 (Korea, Republic of); Lee, Kum Hee [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Yoon, Seung Soo, E-mail: ssyoon@skku.edu [Department of Chemistry, Sungkyunkwan University, Suwon 440-746 (Korea, Republic of); Kim, Young Kwan, E-mail: kimyk@hongik.ac.kr [Department of Information Display, Hongik University, Seoul 121-791 (Korea, Republic of)

    2013-10-01

    The authors have demonstrated a highly efficient and stable phosphorescent white organic light-emitting diode (WOLED), which has been achieved by doping only one orange phosphorescent emitter, Bis(5-benzoyl-2-(4-fluorophenyl)pyridinato-C,N)iridium(III) acetylacetonate into an appropriate deep blue phosphorescent host, 4,4'-bis(4-(triphenylsilyl)phenyl)-1,1'-binaphthyl as an emitting layer (EML). The WOLED has been achieved by effective confinement of triplet excitons to emit a warm white color. The optimized WOLED, with a simple structure as a hole transporting layer-EML-electron transporting layer, showed a maximum luminous efficiency of 22.38 cd/A, a maximum power efficiency of 12.01 lm/W, a maximum external quantum efficiency of 7.32%, and CIEx,y coordinates of (0.38,0.42) at 500 cd/m{sup 2}, respectively. - Highlights: • Highly efficient phosphorescent white organic light-emitting diode (WOLED) • Single emitting layer consists of synthesized deep blue host and orange emitter • The WOLED with high EL efficiencies due to efficient triplet exciton confinement.

  7. Luminescence from cavitation bubbles deformed in uniform pressure gradients

    Science.gov (United States)

    Supponen, Outi; Obreschkow, Danail; Kobel, Philippe; Farhat, Mohamed

    2017-09-01

    Presented here are observations that demonstrate how the deformation of millimetric cavitation bubbles by a uniform pressure gradient quenches single-collapse luminescence. Our innovative measurement system captures a broad luminescence spectrum (wavelength range, 300-900 nm) from the individual collapses of laser-induced bubbles in water. By varying the bubble size, driving pressure, and perceived gravity level aboard parabolic flights, we probed the limit from aspherical to highly spherical bubble collapses. Luminescence was detected for bubbles of maximum radii within the previously uncovered range, R0=1.5 -6 mm, for laser-induced bubbles. The relative luminescence energy was found to rapidly decrease as a function of the bubble asymmetry quantified by the anisotropy parameter ζ , which is the dimensionless equivalent of the Kelvin impulse. As established previously, ζ also dictates the characteristic parameters of bubble-driven microjets. The threshold of ζ beyond which no luminescence is observed in our experiment closely coincides with the threshold where the microjets visibly pierce the bubble and drive a vapor jet during the rebound. The individual fitted blackbody temperatures range between Tlum=7000 and Tlum=11 500 K but do not show any clear trend as a function of ζ . Time-resolved measurements using a high-speed photodetector disclose multiple luminescence events at each bubble collapse. The averaged full width at half-maximum of the pulse is found to scale with R0 and to range between 10 and 20 ns.

  8. Too much food may cause reduced growth of blue mussels (Mytilus edulis) – Test of hypothesis and new ‘high Chl a BEG-model’

    DEFF Research Database (Denmark)

    Larsen, Poul S.; Lüskow, Florian; Riisgård, Hans Ulrik

    2018-01-01

    Growth of the blue mussel (Mytilus edulis) is closely related to the biomass of phytoplankton (expressed as concentration of chlorophyll a, Chl a), but the effect of too much food in eutrophicated areas has so far been overlooked. The hypothesis addressed in the present study suggests that high Chl...... a concentrations (> about 8 μg Chl a l−1) result in reduced growth because mussels are not evolutionarily adapted to utilize such high phytoplankton concentrations and to physiologically regulate the amount of ingested food in such a way that the growth rate remains high and constant. We first make a comparison...... the effect of Chl a, but the present study shows that too much food may cause reduced growth of mussels in eutrophicated marine areas regardless of high or moderate salinity above about 10 psu....

  9. Luminescence dating in archaeology

    International Nuclear Information System (INIS)

    Wintle, A.G.

    2001-01-01

    Thermoluminescence (TL) dating is routinely applied to burnt lithic material. Simple fires are capable of enabling stones weighing a few hundred grams to reach 450 o C, thus zeroing the TL signal. TL dates have been obtained for Upper and Lower Paleolithic sites in Europe and the Near East. TL dating continues to be used for dating pottery and for authentification of ceramic works of art. Some recent studies report the use of optically stimulated luminescence (OSL) (also know as photoluminescence) for dating very small samples of quartz, e.g. from small pieces of pottery or frm metallurgical slag The major recent advance has been in the development of a reliable laboratory procedure for using the OSL signal from quartz to obtain the past radiation exposure. The quartz OSL signal is extremely sensitive to light and is reduced to a negligible level on exposure to direct sunlight for radionuclides during burial, signal to date san.sized quartz grains extracted from sediments, The OSL signal is stimulated by 470 nm light from emitting diodes and the detected using flirters centred on 340 nm A similar signal can be obtained from feldspar grain when are exposed to infrared wavelengths around 880 nm. The infrared stimulated luminescence (IRSL) signals is also rapidly depleted by exposure to sunlight, and dating of colluvial deposits from archaeological sites has been reported

  10. Single-mode pumped high air-fill fraction photonic crystal fiber taper for high-power deep-blue supercontinuum sources

    DEFF Research Database (Denmark)

    Sørensen, Simon Toft; Larsen, Casper; Jakobsen, Christian

    2014-01-01

    Dispersion control with axially nonuniform photonic crystal fibers (PCFs) permits supercontinuum (SC) generation into the deep-blue from an ytterbium pump laser. In this Letter, we exploit the full degrees of freedom afforded by PCFs to fabricate a fiber with longitudinally increasing air-fill fr...

  11. Sky-blue emitting bridged diiridium complexes: beneficial effects of intramolecular π-π stacking.

    Science.gov (United States)

    Congrave, Daniel G; Hsu, Yu-Ting; Batsanov, Andrei S; Beeby, Andrew; Bryce, Martin R

    2018-02-06

    The potential of intramolecular π-π interactions to influence the photophysical properties of diiridium complexes is an unexplored topic, and provides the motivation for the present study. A series of diarylhydrazide-bridged diiridium complexes functionalised with phenylpyridine (ppy)-based cyclometalating ligands is reported. It is shown by NMR studies in solution and single crystal X-ray analysis that intramolecular π-π interactions between the bridging and cyclometalating ligands rigidify the complexes leading to high luminescence quantum efficiencies in solution and in doped films. Fluorine substituents on the phenyl rings of the bridge promote the intramolecular π-π interactions. Notably, these non-covalent interactions are harnessed in the rational design and synthesis of the first examples of highly emissive sky-blue diiridium complexes featuring conjugated bridging ligands, for which they play a vital role in the structural and photophysical properties. Experimental results are supported by computational studies.

  12. Blue-Green Algae

    Science.gov (United States)

    ... that taking a specific blue-green algae product (Super Blue-Green Algae, Cell Tech, Klamath Falls, OR) ... system. Premenstrual syndrome (PMS). Depression. Digestion. Heart disease. Memory. Wound healing. Other conditions. More evidence is needed ...

  13. Assessment of the impact of climate change on spatiotemporal variability of blue and green water resources under CMIP3 and CMIP5 models in a highly mountainous watershed

    Science.gov (United States)

    Fazeli Farsani, Iman; Farzaneh, M. R.; Besalatpour, A. A.; Salehi, M. H.; Faramarzi, M.

    2018-04-01

    The variability and uncertainty of water resources associated with climate change are critical issues in arid and semi-arid regions. In this study, we used the soil and water assessment tool (SWAT) to evaluate the impact of climate change on the spatial and temporal variability of water resources in the Bazoft watershed, Iran. The analysis was based on changes of blue water flow, green water flow, and green water storage for a future period (2010-2099) compared to a historical period (1992-2008). The r-factor, p-factor, R 2, and Nash-Sutcliff coefficients for discharge were 1.02, 0.89, 0.80, and 0.80 for the calibration period and 1.03, 0.76, 0.57, and 0.59 for the validation period, respectively. General circulation models (GCMs) under 18 emission scenarios from the IPCC's Fourth (AR4) and Fifth (AR5) Assessment Reports were fed into the SWAT model. At the sub-basin level, blue water tended to decrease, while green water flow tended to increase in the future scenario, and green water storage was predicted to continue its historical trend into the future. At the monthly time scale, the 95% prediction uncertainty bands (95PPUs) of blue and green water flows varied widely in the watershed. A large number (18) of climate change scenarios fell within the estimated uncertainty band of the historical period. The large differences among scenarios indicated high levels of uncertainty in the watershed. Our results reveal that the spatial patterns of water resource components and their uncertainties in the context of climate change are notably different between IPCC AR4 and AR5 in the Bazoft watershed. This study provides a strong basis for water supply-demand analyses, and the general analytical framework can be applied to other study areas with similar challenges.

  14. A highly luminescent dinuclear Eu(III) complex based on 4,4'-bis (4'',4'',4''-trifluoro-1'',3''-dioxobutyl)-o-terphenyl for light-emitting diodes

    International Nuclear Information System (INIS)

    Liu Shenggui; He Pei; Wang Huihui; Shi Jianxin; Gong Menglian

    2009-01-01

    A dinuclear Eu(III) complex Eu 2 (btbt) 3 .4H 2 O.CH 3 CH 2 OH.N(CH 2 CH 3 ) 3 was synthesized, where H 2 (btbt) was 4,4'-bis (4'',4'',4'',-trifluoro-1'',3''-dioxobutyl)-o-terphenyl. The composition and structure of the complex were characterized by elemental analysis, IR, UV-vis and FAB-MS spectroscopy. The complex emits the characteristic red luminescence of Eu 3+ ion due to the 5 D 0 → 7 F J (J = 0-4) transitions under ∼395 nm-light excitation with good luminescent quantum efficiency (32%) and exhibits high thermal stability (337 deg. C). Bright red light-emitting diodes (LEDs) were fabricated by coating the complex onto a ∼395 nm-emitting InGaN chip. When the mass ratio of the red phosphor to the silicone is 1:30, the efficiency of the fabricated LEDs with the europium complex is 0.98 lm w -1 . The CIE chromaticity coordinates of the LEDs are x = 0.6057 and y = 0.3137, which are close to the National Television Standard Committee (NTSC) standard values for red color. The results indicate that the complex may act as a red component in the fabrication of near UV InGaN-based white light-emitting diodes with high color-rendering index.

  15. CW operation of high-power blue laser diodes with polished facets on semi-polar ( 20 2 ¯ 1 ¯ ) GaN substrates

    KAUST Repository

    Pourhashemi, A.; Farrell, R.M.; Cohen, D.A.; Becerra, D.L.; DenBaars, S.P.; Nakamura, S.

    2016-01-01

    Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

  16. CW operation of high-power blue laser diodes with polished facets on semi-polar ( 20 2 ¯ 1 ¯ ) GaN substrates

    KAUST Repository

    Pourhashemi, A.

    2016-10-11

    Continuous wave (CW) operation of high-power blue laser diodes (LDs) with polished facets on semi-polar (202̅1̅) gallium nitride (GaN) substrates is demonstrated. Ridge waveguide LDs were fabricated using indium GaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 452 nm, the peak two-facet CW output power from an LD with uncoated facets was 1.71 W at a current of 3 A, corresponding to an optical power density of 32.04 MW/cm2 on each facet. The dependence of output power on current did not change with repeated CW measurements, indicating that the polished facets did not degrade under high-power CW operation. These results show that polished facets are a viable alternative to cleaved or etched facets for high-power CW semi-polar LDs.

  17. Highly Luminescent Dinuclear Platinum(II) Complexes Incorporating Bis-Cyclometallating Pyrazine-Based Ligands: A Versatile Approach to Efficient Red Phosphors

    OpenAIRE

    Culham, Stacey; Lanoe, Pierre-Henri; Whittle, Victoria; Durrant, Marcus; Williams, Gareth; Kozhevnikov, Valery

    2013-01-01

    A series of luminescent dinuclear platinum(II) complexes incorporating diphenylpyrazine-based bridging ligands ((LH2)-H-n) has been prepared. Both 2,5-diphenylpyrazine ((LH2)-H-2) and 2,3-diphenylpyrazine ((LH2)-H-3) are able to undergo cyclometalation of the two phenyl rings, with each metal ion binding to the two nitrogen atoms of the central heterocycle, giving, after treatment with the anion of dipivaloyl methane (dpm), complexes of formula \\{Pt(dpm)\\}(2)L-n. These compounds are isomers o...

  18. Neutron dosimetry using optically stimulated luminescence

    International Nuclear Information System (INIS)

    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

  19. Anomalous enhancement of nanodiamond luminescence upon heating

    Science.gov (United States)

    Khomich, A. A.; Kudryavtsev, O. S.; Dolenko, T. A.; Shiryaev, A. A.; Fisenko, A. V.; Konov, V. I.; Vlasov, I. I.

    2017-02-01

    Characteristic photoluminescence (PL) of nanodiamonds (ND) of different origin (detonation, HPHT, extracted from meteorite) was studied in situ at high temperatures in the range 20-450 °C. Luminescence was excited using 473 nm laser and recorded in the range 500-800 nm. In contrast to decrease of point defect PL in bulk diamond with temperature, we found that the ND luminescence related to ND surface defects increases almost an order of magnitude upon heating to 200-250 °C. The observed effect reveals that water adsorbed on ND surfaces efficiently quenches PL; water desorption on heating leads to dramatic increase of the radiative de-excitation.

  20. Upconversion luminescence and blackbody radiation in tetragonal YSZ co-doped with Tm(3+) and Yb(3+).

    Science.gov (United States)

    Soares, M R N; Ferro, M; Costa, F M; Monteiro, T

    2015-12-21

    Lanthanide doped inorganic nanoparticles with upconversion luminescence are of utmost importance for biomedical applications, solid state lighting and photovoltaics. In this work we studied the downshifted luminescence, upconversion luminescence (UCL) and blackbody radiation of tetragonal yttrium stabilized zirconia co-doped with Tm(3+) and Yb(3+) single crystals and nanoparticles produced by laser floating zone and laser ablation in liquids, respectively. The photoluminescence (PL) and PL excitation (PLE) were investigated at room temperature (RT). PL spectra exhibit the characteristic lines in UV, blue/green, red and NIR regions of the Tm(3+) (4f(12)) under resonant excitation into the high energy (2S+1)LJ multiplets. Under NIR excitation (980 nm), the samples placed in air display an intense NIR at ∼800 nm due to the (1)G4→(3)H5/(3)H4→(3)H6 transitions. Additionally, red, blue/green and ultraviolet UCL is observed arising from higher excited (1)G4 and (1)D2 multiplets. The power excitation dependence of the UCL intensity indicated that 2-3 low energy absorbed photons are involved in the UCL for low power levels, while for high powers, the identified saturation is dependent on the material size with a enhanced effect on the NPs. The temperature dependence of the UCL was investigated for single crystals and targets used in the ablation. An overall increase of the integrated intensity was found to occur between 12 K and the RT. The thermally activated process is described by activation energies of 10 meV and 30 meV for single crystals and targets, respectively. For the NPs, the UCL was found to be strongly sensitive to pressure conditions. Under vacuum conditions, instead of the narrow lines of the Tm(3+), a wide blackbody radiation was detected, responsible for the change in the emission colour from blue to orange. This phenomenon is totally reversible when the NPs are placed at ambient pressure. The UCL/blackbody radiation in the nanosized material exhibits

  1. The Blue Marble

    Science.gov (United States)

    2002-01-01

    This spectacular Moderate Resolution Imaging Spectroradiometer (MODIS) 'blue marble' image is based on the most detailed collection of true-color imagery of the entire Earth to date. Using a collection of satellite-based observations, scientists and visualizers stitched together months of observations of the land surface, oceans, sea ice, and clouds into a seamless, true-color mosaic of every square kilometer (.386 square mile) of our planet. Most of the information contained in this image came from MODIS, illustrating MODIS' outstanding capacity to act as an integrated tool for observing a variety of terrestrial, oceanic, and atmospheric features of the Earth. The land and coastal ocean portions of this image is based on surface observations collected from June through September 2001 and combined, or composited, every eight days to compensate for clouds that might block the satellite's view on any single day. Global ocean color (or chlorophyll) data was used to simulate the ocean surface. MODIS doesn't measure 3-D features of the Earth, so the surface observations were draped over topographic data provided by the U.S. Geological Survey EROS Data Center. MODIS observations of polar sea ice were combined with observations of Antarctica made by the National Oceanic and Atmospheric Administration's AVHRR sensor-the Advanced Very High Resolution Radiometer. The cloud image is a composite of two days of MODIS imagery collected in visible light wavelengths and a third day of thermal infra-red imagery over the poles. A large collection of imagery based on the blue marble in a variety of sizes and formats, including animations and the full (1 km) resolution imagery, is available at the Blue Marble page. Image by Reto Stockli, Render by Robert Simmon. Based on data from the MODIS Science Team

  2. Temperature and Pressure Sensors Based on Spin-Allowed Broadband Luminescence of Doped Orthorhombic Perovskite Structures

    Science.gov (United States)

    Eldridge, Jeffrey I. (Inventor); Chambers, Matthew D. (Inventor)

    2014-01-01

    Systems and methods that are capable of measuring pressure or temperature based on luminescence are discussed herein. These systems and methods are based on spin-allowed broadband luminescence of sensors with orthorhombic perovskite structures of rare earth aluminates doped with chromium or similar transition metals, such as chromium-doped gadolinium aluminate. Luminescence from these sensors can be measured to determine at least one of temperature or pressure, based on either the intense luminescence of these sensors, even at high temperatures, or low temperature techniques discussed herein.

  3. Improved photocatalytic activity of highly ordered TiO{sub 2} nanowire arrays for methylene blue degradation

    Energy Technology Data Exchange (ETDEWEB)

    Lv, Xiaojun, E-mail: xjlv@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Key Laboratory of Photochemical Conversion and Optoelectronic Materials and HKU-CAS Joint Laboratory on New Materials, Chinese Academy of Sciences, Beijing 100190 (China); Zhang, Hao; Chang, Haixin [WPI-Advanced Institute for Materials Research, Tohoku University, Sendai 980-8578 (Japan)

    2012-10-15

    Although many efforts have been done on the photocatalytic properties of anodic TiO{sub 2} nanotubes, much less work is done on the photocatalytic performance of TiO{sub 2} nanowires. Self-organized anodic TiO{sub 2} nanowire arrays have been fabricated using a simple electrochemical approach and used as photocatalysts in photodegradation of methylene blue (MB) dyes. Here we found for the first time TiO{sub 2} nanowires have better photocatalytic properties and incident photon-to-current efficiency (IPCE) than TiO{sub 2} nanotubes. N doped TiO{sub 2} nanowires showed further enhancement in photodegradation activity and photocurrent response in the visible region. Such TiO{sub 2} nanowires are expected to have great potential in photodegradation of pollutants, photovoltaic solar energy conversion and water splitting for hydrogen generation as well. -- Highlights: Black-Right-Pointing-Pointer TiO{sub 2} nanowire arrays electrode fabricated via anodizing Ti foil. Black-Right-Pointing-Pointer TiO{sub 2} nanowire arrays have higher photodegradation activity. Black-Right-Pointing-Pointer N doped TiO{sub 2} nanowires enhanced visible-light photocatalytic activity.

  4. Study of the electroluminescence of highly stereoregular poly(N-pentenyl-carbazole) for blue and white OLEDs

    Science.gov (United States)

    Liguori, R.; Botta, A.; Pragliola, S.; Rubino, A.; Venditto, V.; Velardo, A.; Aprano, S.; Maglione, M. G.; Prontera, C. T.; De Girolamo Del Mauro, A.; Fasolino, T.; Minarini, C.

    2017-06-01

    The electroluminescence (EL) of isotactic and syndiotactic poly(N-pentenyl-carbazole) (PPK), achieved by coordination polymerization, is studied in order to investigate the interrelation between the polymer tacticity and their physical-chemical properties. The use of these polymers in organic light-emitting diode (OLED) fabrication is also explored. Thermal and x-ray diffraction analyses of PPKs show that the isotactic stereoisomer is semicrystalline, whereas the syndiotactic one is amorphous. Optical analysis of both stereoisomers, carried out on film samples, reveals the presence of two different excimers: ‘sandwich-like’ and ‘partially overlapping’. Nevertheless, the emission intensity ratio between ‘sandwich-like’ and ‘partially overlapping’ excimers is higher in the isotactic than in the syndiotactic stereoisomer. Using the synthesized polymers as OLED emitting layers, the influence of the polymer tacticity on the EL properties of the device is highlighted. In detail, while blue OLEDs are obtained by using the syndiotactic stereoisomer, OLEDs with a multilayer structure fabricated with the isotactic stereoisomer emit white light. The contribution of three different emissions (fluorescence, phosphorescence and electromer emissions) with comparable intensities to the detected white light is discussed.

  5. Efficient degradation of Methylene Blue dye over highly reactive Cu doped strontium titanate (SrTiO3) nanoparticles photocatalyst under visible light.

    Science.gov (United States)

    Rahman, Qazi Inamur; Ahmad, Musheer; Misra, Sunil Kumar; Lohani, Minaxi

    2012-09-01

    Visible light induced photocatalysts of Cu doped SrTiO3 (Cu/SrTiO3) nanoparticles with the size -60-75 nm were prepared via facile sol-gel method. The morphological, optical, crystalline properties and compositions of synthesized Cu/SrTiO3 nanoparticles were thoroughly characterized by field emission scanning electron microscopy (FE-SEM), powder X-ray diffraction (XRD), ultra violet-visible spectroscopy (UV-Vis) and energy dispersive X-ray (EDX). A significant red shift in the UV-diffused reflectance spectrum was observed and the absorption edge shifted to visible region by the Cu doping. Surprisingly, the band gap of SrTiO3 was changed from 3.2 eV drop to 2.96 eV. The photocatalytic activity of the synthesized Cu/SrTiO3 nanoparticles was demonstrated for the degradation of Methylene Blue dye under visible light irradiation. The formation of new acceptor region in Cu/SrTiO3 was responsible for high photocatalytic activity of Cu/SrTiO3 nanoparticles. The results showed that the Methylene Blue dye was degraded by -66% within time span of 2 h over the Cu/SrTiO3 nanoparticles. This dye degradation reaction followed the Langmuir-Hinshelwood kinetics and also exhibited first order reaction rate. The calculated rate constant for the degradation reaction following first order kinetics was k = 0.0016 min(-1).

  6. Red photoluminescent property and modification of WO3:Eu3+ inverse opal for blue light converted LEDs

    Science.gov (United States)

    Ruan, Jiufeng; Yang, Zhengwen; Huang, Anjun; Chai, Zhuangzhuang; Qiu, Jianbei; Song, Zhiguo

    2018-01-01

    Blue light converted light-emitting diodes is of great significance as a candidate for next generation lighting. In this work, the WO3:Eu3+ inverse opal photonic crystals were prepared and their luminescence properties were studied. The results demonstrated that the main excitation peak of WO3:Eu3+ inverse opals were located at 465 nm. The red luminescence peak at the 613 nm was observed in the WO3:Eu3+ inverse opal upon 465 nm excitation, exhibiting better red color purity. The influence of photonic band gap on the photoluminescence of WO3:Eu3+ inverse opal was obtained. When the red luminescence peak is in the regions of the photonic band gap and the edge of the band-gap, the red luminescence suppression and enhancement was observed respectively. The WO3:Eu3+ inverse opals may be a promising candidate for the blue light converted LEDs.

  7. Investigating the use of Egyptian blue in Roman Egyptian portraits and panels from Tebtunis, Egypt

    Science.gov (United States)

    Ganio, Monica; Salvant, Johanna; Williams, Jane; Lee, Lynn; Cossairt, Oliver; Walton, Marc

    2015-11-01

    The use of the pigment Egyptian blue is investigated on a corpus of fifteen mummy portraits and Roman-period paintings from Tebtunis, Egypt, housed in the Phoebe A. Hearst Museum of Anthropology at the University of California, Berkeley. Egyptian blue has a strong luminescence response in the near infrared that can be exploited to created wide-field images noninvasively showing the distribution of the pigment on a work of art. A growing body of publications in the last decade highlights the increasing use of this tool and its sensitive detection limits. However, the technique is not wavelength specific. Both excitation and emission occur in a broad range. Although Egyptian blue has a strong emission in the NIR, a myriad of other compounds may emit light in this spectral region when excited in the visible. The limited number of studies including complementary analysis to verify the presence of Egyptian blue does not allow its identification on the basis of NIR luminescence alone. Through the use of in situ X-ray fluorescence and X-ray diffraction, and scanning electron microscopy/energy-dispersive spectroscopy of cross sections, this paper confirms the identification of Egyptian blue by NIR luminescence in unexpected areas, i.e., those not blue in appearance.

  8. Thermo-luminescent dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Reither, M; Schorn, B; Schneider, E

    1981-01-01

    The development of paediatric radiology which began in the late 195O's has been characterised by the need to limit the dose of ionising radiation to which the child is subjected. The aim has been to keep radiation exposure as low as possible by the introduction of suitable techniques and by the development of new methods. It is therefore surprising that studies in dosimetry in the paediaytric age range have only been carried out in recent years. One reason for this may have been the fact that a suitable technique of measurement was not available at the time. The introduction of solid state dosimetry based on thermo-luminescence, first into radiotherapy (1968) and subsequently into radiodiagnosis, has made it possible to abandon the previously widely used ionisation chamber. The purpose of the present paper is to indicate the suitability of this form of dose measurement for paediatric radiological purposes and to stimulate its application in this field.

  9. Persistent luminescence nanothermometers

    Science.gov (United States)

    Martín Rodríguez, Emma; López-Peña, Gabriel; Montes, Eduardo; Lifante, Ginés; García Solé, José; Jaque, Daniel; Diaz-Torres, Luis Armando; Salas, Pedro

    2017-08-01

    Persistent phosphorescence nanoparticles emitting in the red and near-infrared spectral regions are strongly demanded as contrast nanoprobes for autofluorescence free bioimaging and biosensing. In this work, we have developed Sr4Al14O25:Eu2+, Cr3+, Nd3+ nanopowders that produce persistent red phosphorescence peaking at 694 nm generated by Cr3+ ions. This emission displays temperature sensitivity in the physiological temperature range (20-60 °C), which makes these nanoparticles potentially useful as fluorescence (contactless) nanothermometers operating without requiring optical excitation. Nd3+ ions, which act as shallow electron traps for the red Cr3+ persistent emission, also display infrared emission bands, extending the fluorescence imaging capability to the second biological window. This unique combination of properties makes these nanoparticles multifunctional luminescent probes with great potential applications in nanomedicine.

  10. Irradiation route to aqueous synthesis of highly luminescent ZnSe quantum dots and its function as a copper ion fluorescence sensor

    Energy Technology Data Exchange (ETDEWEB)

    Rao, Yeluri Narayana; Datta, Aparna [UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8 Bidhannagar, Kolkata 700 098 (India); Das, Satyendra K. [Radiochemistry Division, Variable Energy Cyclotron Centre, 1/AF Bidhannagar, Kolkata 700 064 (India); Saha, Abhijit, E-mail: abhijit@alpha.iuc.res.in [UGC-DAE Consortium for Scientific Research, Kolkata Centre, III/LB-8 Bidhannagar, Kolkata 700 098 (India)

    2016-08-15

    Highlights: • Radiation chemical technique can provide a useful route for synthesis of ZnSe QDs. • Chelating nature of ethylene diamine is exploited for capping nanoparticles. • ZnSe QDs can be a suitable sensitive alternative to toxic cadmium-based system. • Cu(II) ion is probed by QDs in the presence of other physiologically relevant ions. - Abstract: Size-controlled synthesis of stable ZnSe QDs with narrow distribution in aqueous environment through conventional soft chemical method still poses a challenge. The proposed radiation assisted strategy demonstrates aqueous synthesis of stable, monodisperse and luminescent ZnSe QDs capped with chelating ethylene diamine under ambient conditions and at room temperature. Radiation chemical method facilitates in slow and in-situ release of selenium ion from sodium selenosulfate. The concentrations of precursors, such as zinc salt, selenium source, ethylene diamine and absorbed radiation (7–90 kGy) dose were optimized for obtaining good quality particles. Selective quenching of luminescence of as-synthesized quantum dots (QDs) by Cu{sup 2+} ions vis-à-vis other physiologically important cations provide evidence for use of ZnSe quantum dots as alternative to toxic Cd-based quantum dots to probe Cu{sup 2+} ions. The linear relation of ratio of loss in emission intensity as a function of concentration of Cu(II) indicates detection limit in nano-molar range.

  11. Towards dating Quaternary sediments using the quartz Violet Stimulated Luminescence (VSL) signal

    DEFF Research Database (Denmark)

    Ankjærgaard, C.; Jain, Mayank; Wallinga, J.

    2013-01-01

    Quaternary sediments using the violet (402 nm) stimulated luminescence (VSL) signal of quartz.We develop and test a new post-blue VSL single aliquot regenerative dose dating protocol, and demonstrate that the VSL signal originates from a deep trap at about 1.9 eV with a thermal lifetime of 1011 years at 10......Quartz optically stimulated luminescence (OSL) dating is widely used to determine the time of deposition and burial of Late Quaternary sediments. Application of the method is usually limited to the past 150,000 years due to early saturation of the OSL signal. Here we explore the potential to date...

  12. Highly efficient blue organic light emitting device using indium-free transparent anode Ga:ZnO with scalability for large area coating

    International Nuclear Information System (INIS)

    Wang Liang; Matson, Dean W.; Polikarpov, Evgueni; Swensen, James S.; Bonham, Charles C.; Cosimbescu, Lelia; Gaspar, Daniel J.; Padmaperuma, Asanga B.; Berry, Joseph J.; Ginley, David S.

    2010-01-01

    Organic light emitting devices have been achieved with an indium-free transparent anode, Ga doped ZnO (GZO). A large area coating technique was used (RF magnetron sputtering) to deposit the GZO films onto glass. The respective organic light emitting devices exhibited an operational voltage of 3.7 V, an external quantum efficiency of 17%, and a power efficiency of 39 lm/W at a current density of 1 mA/cm 2 . These parameters are well within acceptable standards for blue OLEDs to generate a white light with high enough brightness for general lighting applications. It is expected that high-efficiency, long-lifetime, large area, and cost-effective white OLEDs can be made with these indium-free anode materials.

  13. Reflection measurements for luminescent powders

    Science.gov (United States)

    Kroon, R. E.

    2018-04-01

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

  14. Ecosystem and human health impacts from increased corn production: vulnerability assessment of exposure to high nitrate concentrations in groundwater and blue baby syndrome

    Science.gov (United States)

    Garcia, V.; Cooter, E. J.

    2013-12-01

    The Renewable Fuel Standard (RFS) requires oil refiners to reach a target of 15 billion gallons of corn-based ethanol by 2022. However, there are concerns that the broad-scale use of corn as a source of ethanol may lead to unintended economic and environmental consequences. This study applies the geophysical relationships captured with linked meteorological, air quality and agriculture models to examine the impact of corn production before enactment of the RFS in 2002 and at the height of the RFS targets in 2022. In particular, we investigate the probability of high-levels of nitrate in groundwater resulting from increased corn production and then relate this vulnerability to the potential for infants to acquire Methemoglobinemia, or 'Blue Baby Syndrome'. Blue Baby Syndrome (BBS) is a potentially fatal condition that occurs when the hemoglobin (Fe2+) in an infant's red blood cells is oxidized to methemoglobin (Fe3+), preventing the uptake of oxygen from the baby's blood. Exposure to high levels of nitrate in groundwater occur near the intersection of areas where surface water can more readily leach into shallow aquifers, wells are the main source of drinking water, and high nitrogen inputs exist. We use a coupled meteorological, agricultural and air quality model to identify areas vulnerable to increased nitrate contamination and associated risk to acquiring BBS. We first verify the relationship between predictive variables (e.g., nitrogen deposition and fertilization rates, landcover, soils and aquifer type) and nitrate groundwater levels by applying a regression model to over 800 nitrate measurements taken from wells located throughout the US (Figure 1). We then apply the regression coefficients to the coupled model output to identify areas that are at an increased risk for high nitrate groundwater levels in 2022. Finally, we examine the potential change in risk for acquiring BBS resulting from increased corn production by applying an Oral Reference Dose (Rf

  15. Luminescence enhancement in irradiated polyethylene

    International Nuclear Information System (INIS)

    Charlesby, A.; Owen, G.P.

    1976-01-01

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

  16. Insight into highly efficient removal of cadmium and methylene blue by eco-friendly magnesium silicate-hydrothermal carbon composite

    Science.gov (United States)

    Xiong, Ting; Yuan, Xingzhong; Chen, Xiaohong; Wu, Zhibin; Wang, Hou; Leng, Lijian; Wang, Hui; Jiang, Longbo; Zeng, Guangming

    2018-01-01

    Water pollution is one of the forefront environmental problems. Due to the simplification, flexibility and low cost, the adsorption becomes one of the most fashionable technology and the exploitation of adsorbents has drawn greatly attention. In this study, a novel magnesium silicate-hydrothermal carbon composite (MS-C) was synthesized by facile hydrothermal carbonization and used to remove the cadmium (Cd(II)) and methylene blue (MB) from wastewater. It was shown that the porous and lump-like magnesium silicate (MS) was decorated with multiple hydrothermal carbon (HC) via the Csbnd Osbnd Si covalent bonding. Further, the adsorption behavior of Cd(II) and MB based on the MS, HC, and MS-C were systematically investigated. The equilibrium data of both Cd(II) and MB were fitted well with Langmuir model. Compared to pure MS and HC, the adsorption capacity of composite was significantly improved, accompanied by the maximum adsorption capacity of 108 mg/g for Cd(II) and 418 mg/g for MB, respectively. In the Cd(II)-MB binary system, the adsorption of Cd(II) was favored in comparison with that of MB. The removal of Cd(II) was mainly ascribed to electrostatic attraction and the ion exchange interaction. Meanwhile, the adsorption of MB onto adsorbent was driven by the electrostatic attraction, π-π interaction and hydrogen bond. In view of these empirical results and real water treatment, the environmental friendly and low-cost MS-C holds a potential for separate or simultaneous removal of Cd(II) and MB in practical applications.

  17. Process for producing a self luminescent material

    Energy Technology Data Exchange (ETDEWEB)

    Abe, E

    1962-01-28

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

  18. Blue light emitting diodes for optical stimulation of quartz in retrospective dosimetry and dating

    DEFF Research Database (Denmark)

    Bøtter-Jensen, L.; Duller, G.A.T.; Murray, A.S.

    1999-01-01

    Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LE......, preliminary results from ramping the blue light power output with time are demonstrated. It is shown that this technique enables the separation of OSL components with differing stimulation rates.......Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LEDs...... (470 nm) gives order of magnitude greater rate of stimulation in quartz than that from conventional blue-green light filtered from a halogen lamp. A practical blue LED OSL configuration is described. From comparisons of OSL decay curves produced by green and blue light sources, and by examination...

  19. A Radiation Dosimetry Method Using Pulsed Optically Stimulated Luminescence

    International Nuclear Information System (INIS)

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

    1999-01-01

    A method for the determination of absorbed radiation dose is described based on pulsed optically stimulated luminescence (POSL). The method relies upon the stimulation of an irradiated sample with a train of light pulses from a suitable light source (e.g. a laser) using a wavelength which is within the range of wavelengths corresponding to the radiation-induced optical absorption in the irradiated sample. The subsequent emitted light, due to the detrapping of trapped charges and their subsequent recombination with charge of the opposite sign, is synchronously detected in the period between each stimulation pulse. The total luminescence is summed over the desired number of stimulation pulses and this forms the measured POSL signal. By monitoring the emitted light only in the period between stimulation pulses one can reduce the optical filtering required to discriminate between the stimulation light and the emission light; in this way a high measurement efficiency, and, therefore, a high radiation sensitivity (luminescence intensity per unit absorbed dose) is achieved. Key parameters in the method are the intrinsic luminescence lifetime for the material being used as the luminescent detector, the width of the optical stimulation pulse, and the period between pulses. For optimum operation the measurement parameters should be such that both the pulse width and the time between pulses are much less than the luminescence lifetime. By appropriate choice of the power of the optical stimulation, the frequency of the stimulation pulses, and the total stimulation period, one can also re-measure the absorbed dose several times. In this way, a re-read capability is available with the procedure. The method is illustrated using light from a 2nd-harmonic Nd:YAG laser, with irradiated, anion-deficient aluminium oxide as the luminescent detector material. (author)

  20. Dating Last Interglacial Coastal Systems Using New Feldspar Luminescence Technologies

    Science.gov (United States)

    Lamothe, M.

    2017-12-01

    The recent explosion in new luminescence dating technologies offers new opportunities to explore Quaternary marine coastal facies and landforms. However, tectonic and climatic processes controlling the development of Pleistocene coastal lithosomes are commonly obscured by their poorly constrained geological age. Luminescence dating of feldspar probes one order of magnitude deeper into geological time than radiocarbon and more than 5 times the current age range of quartz optically-stimulated luminescence, routinely used in luminescence dating. However, feldspar luminescence stimulated by infrared photons (eg IRSL) is hampered by anomalous fading. Successful correction methods developed by us over the last 15 years did produce sound chronologies but the fading-corrected ages carried large uncertainties. New approaches initiated by other laboratories, mainly in Europe, have isolated high temperature post-IRSL luminescence as this signal seems to be only slightly affected by fading. However, the gain in stability seems to be lessened due to bleachibility issues, generating age overestimations. We developed a novel protocol known as post-isothermal IRSL dating (Pit-IR) that focuses on a dual system of luminescence signals, probing low (50C) and medium (225C) temperature IRSL signals following isothermal treatments of various intensities. These protocols have been tested on Last interglacial coastal sediments in strikingly different GIA contexts along the Atlantic coastal areas of SE USA as well as from Morocco, Brazil and LIG sites in the Mediterranean basin. A systematic analysis of these results would suggest that a) falling-stages sequences are more commonly preserved as the OSL/IRSL ages are preferentially dating from the end of the MIS5e high stand and b) MIS5a marine sediments may be detectable away from areas generally thought to be affected by peripheral bulge collapse.

  1. Blue shift of CdSe/ZnS nanocrystal-labels upon DNA-hybridization

    Directory of Open Access Journals (Sweden)

    Palme Klaus

    2008-05-01

    Full Text Available Abstract Luminescence color multiplexing is one of the most intriguing benefits, which might occur by using semiconductor Quantum Dots (QDs as labels for biomolecules. It was found, that the luminescence of QDs can be quenched, and replaced by a luminescence peak at approximately 460 nm on hybridization with certain regions of Arabidopsis thaliana tissue. This effect is site selective, and it is unclear whether it occurs due to an energy transfer process, or due to quenching and scattering of the excitation light. The article describes methods for phase-transfer of differently coloured, hydrophobically ligated QDs, coupling of DNA strands to the QD's surface, and hybridization of the labelled DNA to different cell types of Arabidopsis thaliana. The reason for the luminescence blue-shift was studied systematically, and narrowed down to the above mentioned causes.

  2. Blue-light emitting triazolopyridinium and triazoloquinolinium salts

    KAUST Repository

    Carboni, Valentina; Su, Xin; Qian, Hai; Aprahamian, Ivan; Credi, Alberto

    2017-01-01

    Compounds that emit blue light are of interest for applications that include optoelectronic devices and chemo/biosensing and imaging. The design and synthesis of small organic molecules that can act as high-efficiency deep-blue-light emitters

  3. High-brightness semipolar (2021¯) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications

    KAUST Repository

    Shen, Chao

    2016-05-25

    A high-brightness, droop-free, and speckle-free InGaN/GaN quantum well blue superluminescent diode (SLD) was demonstrated on a semipolar (2021) GaN substrate. The 447-nm emitting SLD has a broad spectral linewidth of 6.3 nm at an optical power of 123 mW. A peak optical power of 256 mW was achieved at 700 mA CW injection current. By combining YAG:Ce phosphor, SLD-generated white light shows a color-rendering index (CRI) of 68.9 and a correlated color temperature (CCT) of 4340 K. The measured frequency response of the SLD revealed a -3 dB bandwidth of 560 MHz, thus demonstrating the feasibility of the device for both solid-state lighting (SSL) and visible-light communication (VLC) applications. © 2016 Optical Society of America.

  4. High-power blue laser diodes with indium tin oxide cladding on semipolar (202{sup ¯}1{sup ¯}) GaN substrates

    Energy Technology Data Exchange (ETDEWEB)

    Pourhashemi, A., E-mail: pourhashemi@engr.ucsb.edu; Farrell, R. M.; Cohen, D. A.; Speck, J. S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); DenBaars, S. P.; Nakamura, S. [Materials Department, University of California, Santa Barbara, California 93106 (United States); Department of Electrical and Computer Engineering, University of California, Santa Barbara, California 93106 (United States)

    2015-03-16

    We demonstrate a high power blue laser diode (LD) using indium tin oxide as a cladding layer on semipolar oriented GaN. These devices show peak output powers and external quantum efficiencies comparable to state-of-the-art commercial c-plane devices. Ridge waveguide LDs were fabricated on (202{sup ¯}1{sup ¯}) oriented GaN substrates using InGaN waveguiding layers and GaN cladding layers. At a lasing wavelength of 451 nm at room temperature, an output power of 2.52 W and an external quantum efficiency of 39% were measured from a single facet under a pulsed injection current of 2.34 A. The measured differential quantum efficiency was 50%.

  5. High-brightness semipolar (2021¯) blue InGaN/GaN superluminescent diodes for droop-free solid-state lighting and visible-light communications

    KAUST Repository

    Shen, Chao; Ng, Tien Khee; Leonard, John T.; Pourhashemi, Arash; Nakamura, Shuji; DenBaars, Steven P.; Speck, James S.; Alyamani, Ahmed Y.; El-desouki, Munir M.; Ooi, Boon S.

    2016-01-01

    A high-brightness, droop-free, and speckle-free InGaN/GaN quantum well blue superluminescent diode (SLD) was demonstrated on a semipolar (2021) GaN substrate. The 447-nm emitting SLD has a broad spectral linewidth of 6.3 nm at an optical power of 123 mW. A peak optical power of 256 mW was achieved at 700 mA CW injection current. By combining YAG:Ce phosphor, SLD-generated white light shows a color-rendering index (CRI) of 68.9 and a correlated color temperature (CCT) of 4340 K. The measured frequency response of the SLD revealed a -3 dB bandwidth of 560 MHz, thus demonstrating the feasibility of the device for both solid-state lighting (SSL) and visible-light communication (VLC) applications. © 2016 Optical Society of America.

  6. Stability of luminescence in LaPO4, LaPO4 :RE(3+) (RE = Dy, Eu) nanophosphors.

    Science.gov (United States)

    Pimpalshende, D M; Dhoble, S J

    2015-03-01

    The property of high refractive index, low solubility in water as well as stability to high temperature variation of lanthanum phosphate (LaPO4 ) proved it was the most effective candidate for the production of display lamps, and plasma display panel devices and sensors. The morphological and nanostructural characteristics play a key role in the working efficiency of the luminescent material. These properties can be controlled by the synthesis method, which we have adopted in this paper. We have prepared LaPO4 nanoparticles at a relatively low temperature (110 ºC) in polyethylene glycol medium by using a wet chemical one-step synthesis. The phase composition and structural properties of the sample have been characterized by X-ray diffraction, Fourier transform infrared, transmission electron microscopy and the luminescent property by photoluminescence and thermoluminescence. The samples were well crystallized and the average crystallite size of 15 nm has been calculated for pure LaPO4 using the Debye-Scherrer equation. The result from heat-treated samples shows the phase combination and morphological structure of the powder depend on the annealing temperature. The heat treatment changes the structure of LaPO4 from cuboid rods to fine grains at about 600 °C. The emission spectrum of LaPO4 shows the broad emission band at 368 nm and shoulder at 465 nm with emission of blue color when monitored at an excitation wavelength at 256 nm. The stability of phosphor has been studied with respect to humidity, temperature, doping, doping concentration, γ-ray exposures, etc. The prepared nanosized phosphors were thermally stable and may be a promising blue phosphor for lighting technology as well as radiation dosimetry. Copyright © 2014 John Wiley & Sons, Ltd.

  7. Luminescent features of sol–gel derived rare-earth multi-doped oxyfluoride nano-structured phosphors for white LED application

    International Nuclear Information System (INIS)

    Gouveia-Neto, A.S.; Silva, A.F. da; Bueno, L.A.; Costa, E.B. da

    2012-01-01

    Rare-earth doped oxyfluoride 75SiO 2 :25PbF 2 nano-structured phosphors for white-light-emitting diodes were synthesized by thermal treatment of precursor sol–gel derived glasses. Room temperature luminescence features of Eu 3+ , Sm 3+ , Tb 3+ , Eu 3+ /Tb 3+ , and Sm 3+ /Tb 3+ ions incorporated into low-phonon-energy PbF 2 nanocrystals dispersed in the aluminosilicate glass matrix and excited with UV light emitting diode were investigated. The luminescence spectra exhibited strong emission signals in the red (600, 610, 625, and 646 nm), green (548 and 560 nm), and blue (485 nm) wavelength regions. White-light emission was observed in Sm/Tb and Eu/Tb double-doped activated phosphors employing UV-LED excitation at 395 nm. The dependence of the luminescence emission intensities upon annealing temperature and rare-earth concentration was also examined. The results indicated that there exist optimum annealing temperature and activator ion concentration in order to obtain intense visible emission light with high color rendering index. The study suggests that the nanocomposite phosphor based upon 75SiO 2 :25PbF 2 host herein reported is a promising contender for white-light LED applications. - Highlights: ► White-light emission in double-doped activated phosphors employing UV-LED excitation. ► Luminescent features of europium, samarium, and terbium in nanocrystals dispersed in aluminosilicate glass. ► New nanocomposite phosphor host for white-light LED applications.

  8. Goldenphilicity: Luminescent gold compounds

    International Nuclear Information System (INIS)

    Sansores, L.E.

    2002-01-01

    In the solids and molecules different types of bonds are presented depending on the involved atoms, covalent bonds are common among elements of open shell, where more bond orbitals are filled than anti bond orbitals. It is expected that ionic bonds among closed shell atoms which have charges of opposite sign. Bonds type Van der Waals are presented among molecules which have a bipolar moment. It would not be expected bonds among zero charge species, or more generally with the same nominal charge and in any case the attractive forces would be very small. In fact it is expected that two metallic cations to be repelled each other. There recently is evidence that in organic or organometallic compounds could exist attractive interactions between two cations of the d 8 -d 10 -s 2 families. These bonds are weak but stronger than those of Van der Waals. They are compared with the hydrogen bonds. In this work it was reviewed some examples in which the goldenphilicity plays an important role in the luminescence that the gold complexes present. Examples of mono, bi and trinuclear and the structures that these organometallic compounds could take are examined. (Author)

  9. High resolution cathodoluminescence spectroscopy of carbonate cementation in Khurmala Formation (Paleocene-L. Eocene) from Iraqi Kurdistan Region, Northern Iraq

    Science.gov (United States)

    Omer, Muhamed F.; Omer, Dilshad; Zebari, Bahroz Gh.

    2014-12-01

    A combination of high resolution cathodoluminsecnce-spectroscopy (HRS-CL) with spatial electron microprobe analysis and optical microscopy is used to determine paragenesis and history of cementation in the limestones and dolostones of Khurmala Formation which is exposed in many parts of Northern Iraq. Khurmala Formation was subjected to different diagenetic processes such as micritization, compaction, dissolution, neomorphism, pyritization and cementation that occurred during marine to shallow burial stages and culminated during intermediate to deep burial later stages. Five dolomite textures are recognized and classified according to crystal size distribution and crystal-boundary shape. Dolomitization is closely associated with the development of secondary porosity that pre-and postdates dissolution and corrosion; meanwhile such porosity was not noticed in the associated limestones. Microprobe analysis revealed three types of cement, calcite, dolomite and ankerite which range in their luminescence from dull to bright. Cathodoluminescence study indicated four main texture generations. These are (1) unzoned microdolomite of planar and subhedral shape, with syntaxial rim cement of echinoderm that show dull to red luminescence, (2) equant calcite cements filling interparticle pores which shows dull luminescence and weak zonal growth, (3.1) homogenous intrinsic blue stoichiometric calcite with dull luminescence and without activators, (3.2) coarse blocky calcite cement with strong oscillatory zoning and bright orange luminescence which postdates other calcite cements, (4) ankerite cement with red to orange, non-luminescence growth zonation which is the last formed cement.

  10. Aging characteristics of blue InGaN micro-light emitting diodes at an extremely high current density of 3.5 kA cm−2

    International Nuclear Information System (INIS)

    Tian, Pengfei; Liu, Ran; Althumali, Ahmad; Gu, Erdan; Watson, Ian M; Dawson, Martin D

    2016-01-01

    The aging characteristics of blue InGaN micro-light emitting diodes (micro-LEDs) with different sizes have been studied at an extremely high current density 3.5 kA cm −2 for emerging micro-LED applications including visible light communication (VLC), micro-LED pumped organic lasers and optogenetics. The light output power of micro-LEDs first increases and then decreases due to the competition of Mg activation in p-GaN layer and defect generation in the active region. The smaller micro-LEDs show less light output power degradation compared with larger micro-LEDs, which is attributed to the lower junction temperature of smaller micro-LEDs. It is found that the high current density without additional junction temperature cannot induce significant micro-LED degradation at room temperature but the combination of the high current density and high junction temperature leads to strong degradation. Furthermore, the cluster LEDs, composed of a micro-LED array, have been developed with both high light output power and less light output degradation for micro-LED applications in solid state lighting and VLC. (paper)

  11. Synthesis and tunable luminescence properties of Eu2+ and Tb3+-activated Na2Ca4(PO4)3F phosphors based on energy transfer

    International Nuclear Information System (INIS)

    Zhou, Jun; Xia, Zhiguo; You, Hongpeng; Shen, Kai; Yang, Mengxia; Liao, Libing

    2013-01-01

    A series of color-tunable blue–green emitting Na 2 Ca 4 (PO 4 ) 3 F:Eu 2+ ,Tb 3+ phosphors were prepared by a high temperature solid-state reaction. Their luminescence properties reveal that there is an efficient energy transfer from Eu 2+ to Tb 3+ ions via a dipole–quadrupole mechanism where Eu 2+ ions exhibit a strong excitation band in near ultraviolet (UV) region, matching well with the dominant emission band of near UV (350–420 nm) LED chips, and Eu 2+ and Tb 3+ ions can give characteristic blue and green emission light. The varied color of the phosphors from blue to green can be achieved by properly tuning the relative ratio of Eu 2+ to Tb 3+ dopant through the energy transfer from Eu 2+ to Tb 3+ ions. Thermal quenching luminescence results reveal that Na 2 Ca 4 (PO 4 ) 3 F:Eu 2+ ,Tb 3+ exhibits good thermal stability. These results demonstrate that Tb 3+ ion with low 4f–4f absorption efficiency in near UV region can play the role of an activator in narrow green-emitting phosphor through efficient energy feeding by allowing 4f–5d absorption of Eu 2+ with high oscillator strength. The present Eu 2+ –Tb 3+ codoped Na 2 Ca 4 (PO 4 ) 3 F phosphor will have potential application for the near UV white LEDs. - Highlights: ► Color-tunable blue–green Na 2 Ca 4 (PO 4 ) 3 F:Eu 2+ ,Tb 3+ phosphors were prepared. ► Eu 2+ –Tb 3+ energy transfer process and mechanism discussed. ► Thermal quenching properties of blue and green phosphors were studied.

  12. Circularly polarized luminescence of syndiotactic polystyrene

    Science.gov (United States)

    Rizzo, Paola; Abbate, Sergio; Longhi, Giovanna; Guerra, Gaetano

    2017-11-01

    Syndiotactic polystyrene (s-PS) films, when crystallized from the amorphous state by temporary sorption of non-racemic guest molecules (like carvone) not only exhibit unusually high optical activity, both in the UV-Visible and Infrared ranges, but also present circularly polarized luminescence (CPL) with high dissymmetry ratios (g = ΔI/I values in the range 0.02-0.03). Experimental evidences provide support, rather than to the usual molecular circular dichroism, to a supramolecular chiral optical response being extrinsic to the site of photon absorption and emission, possibly associated with a helical morphology of s-PS crystallites.

  13. Developing luminescent lamps with a narrowband emission spectrum and a methodology for testing them

    Energy Technology Data Exchange (ETDEWEB)

    Deviatykh, E.V.; Prokudova, M.A.; Solov' eva, A.B.

    1981-01-01

    During the building of luninescent lamps with tripolar luminophors, several types of narrowband rare-earth luminophors were examined that emit in the blue (lambda maximum=450-455 nanometers), the green (lambda maximum=542-544 namometers) and the red (lambda maximum is approximately equal to 610 nanometers) portions of the spectrum. The basic characteristics of these luminophors are given: the granular composition, emission spectrum and excitation, quantum output, relative brightness, photo and thermal stability, etc. The LBTsT 40 white luminescent lamp with a luminophor composition containing L-47 and L-48 aluminates, and with yttrium oxide (L-49), generated 75-79 lumens per watt after 100 hours of operation. R /sub a/ =83. Efforts are made to develop a luminescent lamp with a perfected luminophor in a 26 millimeter bulb with luminescence of 93 to 100 lumens per watt.

  14. Luminescence sensitivity changes in quartz

    CERN Document Server

    Wintle, A G

    1999-01-01

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

  15. Luminescence in medical image science

    Energy Technology Data Exchange (ETDEWEB)

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

    2016-01-15

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

  16. Emission of blue light from hydrogenated amorphous silicon carbide

    Science.gov (United States)

    Nevin, W. A.; Yamagishi, H.; Yamaguchi, M.; Tawada, Y.

    1994-04-01

    THE development of new electroluminescent materials is of current technological interest for use in flat-screen full-colour displays1. For such applications, amorphous inorganic semiconductors appear particularly promising, in view of the ease with which uniform films with good mechanical and electronic properties can be deposited over large areas2. Luminescence has been reported1 in the red-green part of the spectrum from amorphous silicon carbide prepared from gas-phase mixtures of silane and a carbon-containing species (usually methane or ethylene). But it is not possible to achieve blue luminescence by this approach. Here we show that the use of an aromatic species-xylene-as the source of carbon during deposition results in a form of amorphous silicon carbide that exhibits strong blue luminescence. The underlying structure of this material seems to be an unusual combination of an inorganic silicon carbide lattice with a substantial 'organic' π-conjugated carbon system, the latter dominating the emission properties. Moreover, the material can be readily doped with an electron acceptor in a manner similar to organic semiconductors3, and might therefore find applications as a conductivity- or colour-based chemical sensor.

  17. Dermatoscopy of blue vitiligo.

    Science.gov (United States)

    Chandrashekar, L

    2009-07-01

    Blue vitiligo is a distinct variant of vitiligo characterized by a blue-grey appearance of the skin, which corresponds histologically with absence of epidermal melanocytes and presence of numerous dermal melanophages. A 23-year-old woman of Indian origin with Fitzpatrick skin type V presented with a 1-month history of normoaesthetic depigmented macules over the right forearm, dorsa of the hands and right areola. The macule over the right forearm had a bluish tinge. A clinical diagnosis of vitiligo vulgaris with blue vitiligo was made. Dermatoscopy of the interface between the blue macule and the hypopigmented macule revealed a linear depigmented macule in the centre with multiple blue dots and absence of epidermal melanin on the side of the blue macule, and reticular pigmentation with a few depigmented macules and scattered blue dots over the side of the hypopigmented macule. Blue vitiligo was described previously in a patient seropositive for human immunodeficiency virus, and believed to represent postinflammatory hyperpigmentation in areas bordering the vitiliginous patches as a result of psoralen ultraviolet A treatment. This case is unusual because of its rarity and the description of the associated dermatoscopical findings.

  18. Blue Ocean Thinking

    Science.gov (United States)

    Orem, Donna

    2016-01-01

    This article describes a concept called the "blue ocean thinking strategy," developed by W. Chan Kim and Renée Mauborgne, professors at INSEAD, an international graduate school of business in France. The "blue ocean" thinking strategy considers opportunities to create new markets for services, rather than focusing solely on…

  19. Study on the relationship of protease production and luminescence in Vibrio harveyi.

    Science.gov (United States)

    Nakayama, T; Nomura, N; Matsumura, M

    2006-07-01

    To demonstrate that Vibrio harveyi produces various types of toxins and how the production of those toxins is related with luminescence. Luminescence and toxicity of eight V. harveyi were evaluated. We demonstrated that all V. harveyi emitting luminescence were isolated from marine organisms and also showed that they were highly pathogenic when compared with culture collection V. harveyi based on cytotoxic assay test. On the contrary, V. harveyi isolated from shrimp farm showed no luminescence but showed high pathogenicity based on toxicity test. The effect of protease inhibitors on pathogenicity and luminescence was also investigated. We demonstrated that light emission of pathogenic V. harveyi remarkably decreased after addition of protease inhibitor. Furthermore, extracellular proteins from cell-free culture supernatant of luminescent and nonluminescent V. harveyi were compared using SDS-PAGE analysis. Results showed that there were differences in molecular weight and amount of proteins. Vibrio harveyi parasiting marine organisms have both luminescence and pathogenicity. Based on this study, luminescence and protease toxin activity in V. harveyi are related. Moreover, this paper clarified that V. harveyi produces various types of toxins. The current study demonstrated that V. harveyi produces two kinds of toxins, haemolysin and protease toxin. It may be clear roots of V. harveyi toxin.

  20. Background-free, high sensitivity staining of proteins in one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gels using a luminescent ruthenium complex.

    Science.gov (United States)

    Berggren, K; Chernokalskaya, E; Steinberg, T H; Kemper, C; Lopez, M F; Diwu, Z; Haugland, R P; Patton, W F

    2000-07-01

    SYPRO Ruby dye is a permanent stain comprised of ruthenium as part of an organic complex that interacts noncovalently with proteins. SYPRO Ruby Protein Gel Stain provides a sensitive, gentle, fluorescence-based method for detecting proteins in one-dimensional and two-dimensional sodium dodecyl sulfate-polyacrylamide gels. Proteins are fixed, stained from 3h to overnight and then rinsed in deionized water or dilute methanol/acetic acid solution for 30 min. The stain can be visualized using a wide range of excitation sources commonly used in image analysis systems including a 302 nm UV-B transilluminator, 473 nm second harmonic generation (SHG) laser, 488 nm argon-ion laser, 532 nm yttrium-aluminum-garnet (YAG) laser, xenon arc lamp, blue fluorescent light bulb or blue light-emitting diode (LED). The sensitivity of SYPRO Ruby Protein Gel Stain is superior to colloidal Coomassie Brilliant Blue (CBB) stain or monobromobimane labeling and comparable with the highest sensitivity silver or zinc-imidazole staining procedures available. The linear dynamic range of SYPRO Ruby Protein Gel stain extends over three orders of magnitude, which is vastly superior to silver, zinc-imidazole, monobromobimane and CBB stain. The fluorescent stain does not contain superfluous chemicals (formaldehyde, glutaraldehyde, Tween-20) that frequently interfere with peptide identification in mass spectrometry. While peptide mass profiles are severely altered in protein samples prelabeled with monobromobimane, successful identification of proteins by peptide mass profiling using matrix-assisted laser desorption/ionization mass spectrometry was easily performed after protein detection with SYPRO Ruby Protein Gel stain.

  1. Luminescent properties of Na2CaSiO4:Eu2+ and its potential application in white light emitting diodes

    International Nuclear Information System (INIS)

    Wang, Zhijun; Li, Panlai; Li, Ting; Zhang, Xing; Li, Qingxuan; Yang, Zhiping; Guo, Qinglin

    2013-01-01

    Graphical abstract: Na 2 CaSiO 4 :Eu 2+ phosphor can be effectively excited by an ultraviolet and near-ultraviolet light, and produce a bright blue emission centered at 436 nm. The CIE chromaticity coordinations (x, y) of Na 2 CaSiO 4 :Eu 2+ (NSCE)/Li 2 SrSiO 4 :Eu 2+ (LSSE) vary with the molar ratio of the two constituents. When NSCE/LSSE is 1:3, the CIE chromaticity coordination is (0.332, 0.346), which is close to that of the natural sunlight (0.33, 0.33). The results indicate that Na 2 CaSiO 4 :Eu 2+ may be a promising blue phosphor for UV chip-based multi-phosphor converted white light emitting diodes. Highlights: ► Na 2 CaSiO 4 :Eu 2+ shows the blue emission with a peak at 436 nm and broad excitation band in the UV/n-UV range. ► White light with CIE coordinates (0.332, 0.346) is generated by mixing the blue phosphor with the Li 2 SrSiO 4 :Eu 2+ yellow phosphor. ► Na 2 CaSiO 4 :Eu 2+ would be a promising blue phosphor candidate for UV chip-based multi-phosphor converted white LEDs. - Abstract: A novel blue phosphor Na 2 CaSiO 4 :Eu 2+ is synthesized by a high temperature solid-state reaction, and its luminescent properties are systematically studied. Na 2 CaSiO 4 :Eu 2+ can be effectively excited by the 354 nm radiation, and create blue emission (436 nm). The emission intensity of Na 2 CaSiO 4 :Eu 2+ is influenced by the Eu 2+ doping content, and the optimal doping content is 1.5%, and the concentration quenching mechanism of Eu 2+ in Na 2 CaSiO 4 can be attributed to the multipolar interaction. The white light with CIE coordinates (0.332, 0.346) is generated by mixing the blue phosphor Na 2 CaSiO 4 :Eu 2+ with the yellow phosphor Li 2 SrSiO 4 :Eu 2+ . The results indicate that Na 2 CaSiO 4 :Eu 2+ may be a potential blue emitting phosphor for UV chip-based multi-phosphor converted white light emitting diodes

  2. Hierarchically ordered macro-mesoporous ZnS microsphere with reduced graphene oxide supporter for a highly efficient photodegradation of methylene blue

    Energy Technology Data Exchange (ETDEWEB)

    Sookhakian, M., E-mail: m.sokhakian@gmail.com [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); Amin, Y.M. [Department of Physics, University of Malaya, Kuala Lumpur 50603 (Malaysia); Basirun, W.J. [Department of Chemistry, University of Malaya, Kuala Lumpur 50603 (Malaysia); Centre of Research in Nanotechnology and Catalysis (NanoCat), Institute of Postgraduate Studies, University Malaya, Kuala Lumpur 50603 (Malaysia)

    2013-10-15

    A facile one-pot method for the fabrication of high quality self-assembled hierarchically ordered macro-mesoporous ZnS microsphere–reduced graphene oxide (RGO) composite without the use of templates or surfactants is described. During the hydrothermal process, reduced graphene oxide (RGO) was loaded into the ZnS microsphere by in situ reduction of graphene oxide added in the self-assembly system. The morphology and structure of the as-prepared composites were confirmed by X-ray diffraction, high resolution transmission electron microscopy, energy dispersive X-ray analysis, Fourier transform infrared spectroscopy and Raman spectroscopy. Incorporation of reduced graphene oxide as an excellent electron-transporting material effectively suppresses the charge recombination. Hence, a significant enhancement in the photocatalytic efficiency for the photodegradation of methylene blue was observed with the ZnS–RGO composite, compared to the pure ZnS. Overall, this research results may lay down new vistas for the in situ fabrication of the ZnS–RGO composite as a highly efficient photocatalysis under visible-light irradiation and their applications in environmental protection.

  3. High Power Efficiency Solution-Processed Blue Phosphorescent Organic Light-Emitting Diodes Using Exciplex-Type Host with a Turn-on Voltage Approaching the Theoretical Limit.

    Science.gov (United States)

    Ban, Xinxin; Sun, Kaiyong; Sun, Yueming; Huang, Bin; Ye, Shanghui; Yang, Min; Jiang, Wei

    2015-11-18

    Three solution-processable exciplex-type host materials were successfully designed and characterized by equal molar blending hole transporting molecules with a newly synthesized electron transporting material, which possesses high thermal stability and good film-forming ability through a spin-coating technique. The excited-state dynamics and the structure-property relationships were systematically investigated. By gradually deepening the highest occupied molecular orbital (HOMO) level of electron-donating components, the triplet energy of exciplex hosts were increased from 2.64 to 3.10 eV. Low temperature phosphorescence spectra demonstrated that the excessively high triplet energy of exciplex would induce a serious energy leakage from the complex state to the constituting molecule. Furthermore, the low energy electromer state, which only exists under the electroexcitation, was found as another possible channel for energy loss in exciplex-based phosphorescent organic light-emitting diodes (OLEDs). In particular, as quenching of the exciplex-state and the triplet exciton were largely eliminated, solution-processed blue phosphorescence OLEDs using the exciplex-type host achieved an extremely low turn-on voltage of 2.7 eV and record-high power efficiency of 22.5 lm W(-1), which were among the highest values in the devices with identical structure.

  4. Zero- and two-dimensional hybrid carbon phosphors for high colorimetric purity white light-emission.

    Science.gov (United States)

    Ding, Yamei; Chang, Qing; Xiu, Fei; Chen, Yingying; Liu, Zhengdong; Ban, Chaoyi; Cheng, Shuai; Liu, Juqing; Huang, Wei

    2018-03-01

    Carbon nanomaterials are promising phosphors for white light emission. A facile single-step synthesis method has been developed to prepare zero- and two-dimensional hybrid carbon phosphors for the first time. Zero-dimensional carbon dots (C-dots) emit bright blue luminescence under 365 nm UV light and two-dimensional nanoplates improve the dispersity and film forming ability of C-dots. As a proof-of-concept application, the as-prepared hybrid carbon phosphors emit bright white luminescence in the solid state, and the phosphor-coated blue LEDs exhibit high colorimetric purity white light-emission with a color coordinate of (0.3308, 0.3312), potentially enabling the successful application of white emitting phosphors in the LED field.

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

    Science.gov (United States)

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

    2013-11-21

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

  6. Luminescence characterization of a sodium rich feldspar

    International Nuclear Information System (INIS)

    Correcher, V.; Sanchez M, L.; Garcia G, J.; Rivera, T.

    2006-01-01

    This paper reports on the radioluminescence (RL) and thermoluminescence (TL) properties of a sodium rich feldspar ((Na,K)[AlSi 3 O 8 ]) with a mean molecular composition of orthoclase (Or) and albite (Ab) of Or 1 Ab 99 . Despite the complexity of the luminescence signals of the sample, it is possible to determine six different emission bands at about 300, 380, 420, 460, 550 and 680 nm. The 300 nm emission can be associated to structural defects related to the recombination process in which the Na + ion diffusion-limited is involved. The UV-blue emission band at (i) 380 nm is characteristic of mineral phases containing SiO 4 tetrahedral and could be related to intrinsic defects in the lattice, (ii) the 420 nm band could be associated to the presence of Cu (II) ions placed next to the hole traps or the recombination on a centre formed from a hole-oxygen atom adjacent to two Al atoms (Al-O-Al) and (iii) the 460 nm waveband could be due to the presence of Ti 4+ . The green and red emissions are respectively associated to the presence of Mn 2+ and Fe 3+ ions. The ratio between the relative intensities, peaked at 290 (the more intense waveband) and 550 nm is about 10:1 in both TL and RL; this fact indicates that the efficiency of recombination centres does no changes regardless on the type of the process. (Author)

  7. On luminescence lifetimes in quartz

    International Nuclear Information System (INIS)

    Chithambo, M.L.; Galloway, R.B.

    2000-01-01

    In this paper we present results of investigations concerning the time dependence of luminescence emission relative to the time of stimulation in quartz. Measurements of time-resolved spectra were performed on a new versatile pulsed light emitting diode system using 525 nm stimulation, an 11 μs duration pulse, a repetition rate of 11 kHz and a 64 μs dynamic range. Effects on luminescence lifetime resulting from sample treatments such as optical stimulation, irradiation, and preheating, are reported

  8. Red, green, blue and white light upconversion emission in Yb3+/Tm3+/Ho3+ co-doped tellurite glasses

    International Nuclear Information System (INIS)

    Desirena, H; De la Rosa, E; Meza, O; Salas, P

    2011-01-01

    Several Yb 3+ /Tm 3+ /Ho 3+ co-doped transparent TeO 2 -ZnO-Na 2 O-Yb 2 O 3 -Ho 2 O 3 -Tm 2 O 3 glasses were prepared and luminescence properties were characterized. Simultaneous red, green and blue (RGB) emission were obtained after excitation at 970 nm. Colour emission was tuned from multicolour to white light with colour coordinate (0.32, 0.33) matching very well with the white reference (0.33, 0.33). Changes in colour emission were obtained by varying the intensity ratios between RGB bands that are strongly concentration dependent because of the interaction of co-dopants. The colour tunability, high quality of white light and high intensity of the emitted signal make these transparent glasses excellent candidates for applications in solid-state lighting.

  9. The blues broaden, but the nasty narrows: attentional consequences of negative affects low and high in motivational intensity.

    Science.gov (United States)

    Gable, Philip; Harmon-Jones, Eddie

    2010-02-01

    Positive and negative affects high in motivational intensity cause a narrowing of attentional focus. In contrast, positive affects low in motivational intensity cause a broadening of attentional focus. The attentional consequences of negative affects low in motivational intensity have not been experimentally investigated. Experiment 1 compared the attentional consequences of negative affect low in motivational intensity (sadness) relative to a neutral affective state. Results indicated that low-motivation negative affect caused attentional broadening. Experiment 2 found that disgust, a high-motivation negative affect not previously investigated in attentional studies, narrowed attentional focus. These experiments support the conceptual model linking high-motivation affective states to narrowed attention and low-motivation affective states to broadened attention.

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

    International Nuclear Information System (INIS)

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

    2014-01-01

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

  11. Luminescent properties of praseodymium in some fluorides

    International Nuclear Information System (INIS)

    Potapov, A.S.; Rodnyj, P.A.; Mikhrin, S.B.; Magunov, I.R.

    2005-01-01

    Influence of diverse factors on efficiency of the Pr 3+ cascade emission in BaF 2 : Pr and SrAlF 5 : Pr. The effect of the environment of the luminescence center on the mutual position of the lowest 5d and the 4f level 1 S 0 of Pr 3+ ion is considered. PrF 3 clustering in BaF 2 is observed at a high praseodymium concentration. The promising potential of magnesium as a charge compensator for praseodymium in SrAlF 5 is demonstrated [ru

  12. Fabrication and properties of highly luminescent materials from Tb(OH)3-SiO2 and Tb(OH)3-SiO2:Eu3+ nanotubes

    International Nuclear Information System (INIS)

    Tran Thu Huong; Tran Kim Anh; Le Quoc Minh

    2009-01-01

    Luminescent nanomaterials with one-dimensional (1D) structures have attracted much attention due to their unique properties and potential applications in nanophotonics and nanobiophotonics. In this paper, we report a synthesis of terbium - hydroxide - at - silica Tb(OH) 3 -SiO 2 and Tb(OH) 3 -SiO 2 :Eu 3+ nanotubes. Terbium - hydroxide tubes were synthesized by soft template method. The size of the tubes can be controlled precisely and have outer diameters ranging from 80 to 120 nm, wall thickness of about 30 nm, and lengths ranging from 300 to 800 nm. To fabricate core/shell materials, the seed growth method is used. FESEM, X-ray diffraction, Raman spectra of Tb(OH) 3 and Tb(OH) 3 -SiO 2 nanotubes were investigated. The photoluminescence (PL) spectrum of Tb(OH) 3 under 325 nm excitation consists of four main peaks at 488, 542, 582, and 618 nm. Furthermore, a preliminary suggestion for the mechanism of growth of the Tb(OH) 3 nanotubes using the soft - template synthesis technique has been proposed. The PL intensity from Tb(OH) 3 -SiO 2 or Tb(OH) 3 -SiO 2 :Eu 3+ nanotubes is much stronger than that of Tb(OH) 3 .

  13. Fiber-coupled Luminescence Dosimetry in Therapeutic and Diagnostic Radiology

    DEFF Research Database (Denmark)

    Andersen, Claus Erik

    2011-01-01

    . Some crystalline phosphors, such as carbon-doped aluminium oxide (Al2O3:C) have the ability to store charge produced in the crystal during irradiation. The stored charge may later be released by fiber-guided laser light under emission of so-called optically stimulated luminescence (OSL). The OSL signal......Fiber-coupled luminescence dosimetry is an emerging technology with several potentially attractive features of relevance for uses in therapeutic and diagnostic radiology: direct water equivalence (i.e. no significant perturbation of the radiation field in a water phantom or a patient), sub......-mm detector size, high dynamic range (below a mGy to several Gy), microsecond time resolution, and absence of electrical wires or other electronics in the dosimeter probe head. Fiber-coupled luminescence dosimetry systems typically consist of one or more small samples of phosphor, e.g. a mg of plastic...

  14. Afterglow luminescence in sol-gel/Pechini grown oxide materials: persistence or phosphorescence process? (Conference Presentation)

    Science.gov (United States)

    Sontakke, Atul; Ferrier, Alban; Viana, Bruno

    2017-03-01

    Persistent luminescence and phosphorescence, both yields afterglow luminescence, but are completely different mechanisms. Persistent luminescence involves a slow thermal release of trapped electrons stored in defect states, whereas the phosphorescence is caused due to triplet to singlet transition [1,2]. Many persistent luminescence phosphors are based on oxide inorganic hosts, and exhibit long afterglow luminescence after ceasing the excitation. We observed intense and long afterglow luminescence in sol-gel/pechini grown inorganic oxides, and as a first interpretation thought to be due to persistence mechanism. However, some of these materials do not exhibit defect trap centers, and a detailed investigation suggested it is due to phosphorescence, but not the persistence. Phosphorescence is not common in inorganic solids, and that too at room temperature, and therefore usually misinterpreted as persistence luminescence [3]. Here we present a detailed methodology to distinguish phosphorescence from persistence luminescence in inorganic solids, and the process to harvest highly efficient long phosphorescence afterglow at room temperature. 1. Jian Xu, Setsuhisa Tanabe, Atul D. Sontakke, Jumpei Ueda, Appl. Phys. Lett. 107, 081903 (2015) 2. Sebastian Reineke, Marc A. Baldo, Scientific Reports, 4, 3797 (2014) 3. Pengchong Xue, Panpan Wang, Peng Chen, Boqi Yao, Peng Gong, Jiabao Sun, Zhenqi Zhang, Ran Lu, Chem. Sci. (2016) DOI: 10.1039/C5SC03739E

  15. Advantages and disadvantages of luminescence dosimetry

    Energy Technology Data Exchange (ETDEWEB)

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

    2010-03-15

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

  16. Novel Mechano-Luminescent Sensors Based on Piezoelectric/Electroluminescent Composites

    Directory of Open Access Journals (Sweden)

    Yunzhang Fang

    2011-04-01

    Full Text Available A high-sensitivity mechano-luminescent sensor was fabricated on the basis of piezoelectric/electroluminescent composites. The working principle of this mechano-luminescent sensor was elucidated by analyzing the relationship between the piezoelectric-induced charges and the electroluminescent effects. When a stress is applied on the piezoelectric layer, electrical charges will be induced at both the top and bottom sides of the piezoelectric layer. The induced electrical charges will lead to a light output from the electroluminescent layer, thus producing a mechano-luminescence effect. By increasing the vibration strength or frequency applied, the mechano-luminescence output can be obviously enhanced. Mechano-luminescence sensors have potential in smart stress-to-light devices, such as foot-stress-distribution-diagnosis systems and dynamic-load-monitors for bridge hanging cables.

  17. Organic scintillators with long luminescent lifetimes for radiotherapy dosimetry

    DEFF Research Database (Denmark)

    Beierholm, Anders Ravnsborg; Lindvold, Lars René; Andersen, Claus Erik

    2011-01-01

    of experiments performed using two organic scintillators, one commercially available and one custom made. The luminescent lifetimes of the scintillators have been measured using i) optical excitation by pulsed UV light, and ii) irradiative excitation using high-energy X-rays from a linac. A luminescent lifetime...... component on the order of 20 μs was estimated for the custom-made organic scintillator, while the commercial scintillator exhibited a fast component of approximately 5 ns lifetime (7 ns as stated by the manufacturer) and an approximate 10 μs lifetime slow component. Although these lifetimes are not long...

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

    International Nuclear Information System (INIS)

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

    2015-01-01

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

  19. One-Pot Route towards Active TiO2 Doped Hierarchically Porous Cellulose: Highly Efficient Photocatalysts for Methylene Blue Degradation

    Directory of Open Access Journals (Sweden)

    Xiaoxia Sun

    2017-03-01

    Full Text Available In this study, novel photocatalyst monolith materials were successfully fabricated by a non-solvent induced phase separation (NIPS technique. By adding a certain amount of ethyl acetate (as non-solvent into a cellulose/LiCl/N,N-dimethylacetamide (DMAc solution, and successively adding titanium dioxide (TiO2 nanoparticles (NPs, cellulose/TiO2 composite monoliths with hierarchically porous structures were easily formed. The obtained composite monoliths possessed mesopores, and two kinds of macropores. Scanning Electron Microscope (SEM, Energy Dispersive Spectroscopy (EDS, Fourier Transform Infrared Spectroscopy (FT-IR, X-ray Diffraction (XRD, Brunauer-Emmett-Teller (BET, and Ultraviolet-visible Spectroscopy (UV-Vis measurements were adopted to characterize the cellulose/TiO2 composite monolith. The cellulose/TiO2 composite monoliths showed high efficiency of photocatalytic activity in the decomposition of methylene blue dye, which was decomposed up to 99% within 60 min under UV light. Moreover, the composite monoliths could retain 90% of the photodegradation efficiency after 10 cycles. The novel NIPS technique has great potential for fabricating recyclable photocatalysts with highly efficiency.

  20. Blue ocean strategy.

    Science.gov (United States)

    Kim, W Chan; Mauborgne, Renée

    2004-10-01

    Despite a long-term decline in the circus industry, Cirque du Soleil profitably increased revenue 22-fold over the last ten years by reinventing the circus. Rather than competing within the confines of the existing industry or trying to steal customers from rivals, Cirque developed uncontested market space that made the competition irrelevant. Cirque created what the authors call a blue ocean, a previously unknown market space. In blue oceans, demand is created rather than fought over. There is ample opportunity for growth that is both profitable and rapid. In red oceans--that is, in all the industries already existing--companies compete by grabbing for a greater share of limited demand. As the market space gets more crowded, prospects for profits and growth decline. Products turn into commodities, and increasing competition turns the water bloody. There are two ways to create blue oceans. One is to launch completely new industries, as eBay did with online auctions. But it's much more common for a blue ocean to be created from within a red ocean when a company expands the boundaries of an existing industry. In studying more than 150 blue ocean creations in over 30 industries, the authors observed that the traditional units of strategic analysis--company and industry--are of limited use in explaining how and why blue oceans are created. The most appropriate unit of analysis is the strategic move, the set of managerial actions and decisions involved in making a major market-creating business offering. Creating blue oceans builds brands. So powerful is blue ocean strategy, in fact, that a blue ocean strategic move can create brand equity that lasts for decades.

  1. Too much food may cause reduced growth of blue mussels (Mytilus edulis) - Test of hypothesis and new 'high Chl a BEG-model'

    Science.gov (United States)

    Larsen, Poul S.; Lüskow, Florian; Riisgård, Hans Ulrik

    2018-04-01

    Growth of the blue mussel (Mytilus edulis) is closely related to the biomass of phytoplankton (expressed as concentration of chlorophyll a, Chl a), but the effect of too much food in eutrophicated areas has so far been overlooked. The hypothesis addressed in the present study suggests that high Chl a concentrations (> about 8 μg Chl a l-1) result in reduced growth because mussels are not evolutionarily adapted to utilize such high phytoplankton concentrations and to physiologically regulate the amount of ingested food in such a way that the growth rate remains high and constant. We first make a comparison of literature values for actually measured weight-specific growth rates (μ, % d-1) of small (20 to 25 mm) M. edulis, either grown in controlled laboratory experiments or in net bags in Danish waters, as a function of Chl a. A linear increase up to about μ = 8.3% d-1 at 8.1 μg Chl a l-1 fits the "standard BEG-model" after which a marked decrease takes place, and this supports the hypothesis. A "high Chl a BEG-model", applicable to newly settled post-metamorphic and small juvenile (non-spawning) mussels in eutrophicated Danish and other temperate waters, is developed and tested, and new data from a case study in which the growth of mussels in net bags was measured along a Chl a gradient are presented. Finally, we discuss the phenomenon of reduced growth of mussels in eutrophicated areas versus a possible impact of low salinity. It is concluded that it is difficult to separate the effect of salinity from the effect of Chl a, but the present study shows that too much food may cause reduced growth of mussels in eutrophicated marine areas regardless of high or moderate salinity above about 10 psu.

  2. Comparison of a novel high-power blue diode laser (λ=442 nm) with Ho:YAG (λ=2100 nm), Tm fiber (λ=1940 nm), and KTP (λ=532 nm) lasers for soft tissue ablation

    Science.gov (United States)

    Vinnichenko, Victoriya; Kovalenko, Anastasiya; Arkhipova, Valeriya; Yaroslavsky, Ilya; Altshuler, Gregory; Gapontsev, Valentin

    2018-02-01

    Three lasers were directly compared, including the Ho:YAG laser (λ = 2100 nm), Tm fiber laser (λ = 1940 nm) operating in 3 different modes (CW, regular pulse, and super pulse), and blue diode laser (λ = 442 nm) for vaporization and coagulation efficiency for treating blood-rich soft tissues, ex vivo, in a porcine kidney model at quasi-contact cutting in water. In addition, experimental results were compared with published data on performance of KTP laser (λ = 532 nm) at similar experimental settings (Power = 60 W and cutting speed = 2 mm/s). Tm fiber laser in pulsed mode and blue laser produced highest vaporization rates of 3.7 and 3.4 mm3/s, respectively. Tm fiber laser (in both CW and pulsed modes) also produced the largest coagulation zone among the laser sources tested. A carbonization zone was observed for Tm fiber laser in CW and pulsed modes, as well as for the blue diode laser. Tm fiber laser in super-pulse mode and Ho:YAG laser both resulted in irregular coagulation zones without carbonization. Comparison with known data for KTP laser revealed that tissue effects of the blue laser are similar to that of the KTP laser. These results suggest that the combination of the two lasers (Tm fiber and blue diode) in one system may achieve high cutting efficiency and optimal coagulation for hemostasis during surgical treatment. Ex vivo testing of the combined system revealed feasibility of this approach. The combination of the CW Tm fiber laser (120W) and the blue diode laser (60W) emitting through a combination tip were compared with CW 120 W Tm fiber laser alone and 120 W Ho:YAG laser. Vaporization rates measured 34, 28, and 6 mm3/s, and coagulation zones measured 0.6, 1.3, and 1.7 mm, respectively. A carbonization zone was only observed with CW Tm fiber laser. The vaporization rate of combined CW Tm fiber laser / blue diode laser was comparable to published data for KTP laser for equivalent total power. Thus, high-power blue diode laser, Tm fiber laser, and

  3. Hydrothermal synthesis, characterization and luminescent ...

    Indian Academy of Sciences (India)

    Home; Journals; Bulletin of Materials Science; Volume 39; Issue 4. Hydrothermal synthesis, characterization and luminescent properties of lanthanide-doped NaLaF 4 nanoparticles. JIGMET LADOL HEENA KHAJURIA SONIKA KHAJURIA ... Keywords. Citric acid; X-ray diffraction; down-conversion emission; energy transfer.

  4. Hydrothermal synthesis, characterization and luminescent ...

    Indian Academy of Sciences (India)

    that nanoparticles have cylindrical shape and crystalline nature of nanoparticles was confirmed by SAED patterns. Down- conversion (DC) luminescent properties of doped NaLaF4 were also .... Figure 1 shows the XRPD patterns of undoped NaLaF4 and .... which can be assigned to the transitions from the 7F6 ground.

  5. Origin of blue photoluminescence from colloidal silicon nanocrystals fabricated by femtosecond laser ablation in solution.

    Science.gov (United States)

    Hao, H L; Wu, W S; Zhang, Y; Wu, L K; Shen, W Z

    2016-08-12

    We present a detailed investigation into the origin of blue emission from colloidal silicon (Si) nanocrystals (NCs) fabricated by femtosecond laser ablation of Si powder in 1-hexene. High resolution transmission electron microscopy and Raman spectroscopy observations confirm that Si NCs with average size 2.7 nm are produced and well dispersed in 1-hexene. Fourier transform infrared spectrum and x-ray photoelectron spectra have been employed to reveal the passivation of Si NCs surfaces with organic molecules. On the basis of the structural characterization, UV-visible absorption, temperature-dependent photoluminescence (PL), time-resolved PL, and PL excitation spectra investigations, we deduce that room-temperature blue luminescence from colloidal Si NCs originates from the following two processes: (i) under illumination, excitons first form within colloidal Si NCs by direct transition at the X or Γ (Γ25 → Γ'2) point; (ii) and then some trapped excitons migrate to the surfaces of colloidal Si NCs and further recombine via the surface states associated with the Si-C or Si-C-H2 bonds.

  6. Dominant ultraviolet-blue photoluminescence of ZnO embedded into synthetic opal

    International Nuclear Information System (INIS)

    Abrarov, S.M.; Yuldashev, Sh.U.; Kim, T.W.; Lee, S.B.; Kwon, H.Y.; Kang, T.W.

    2005-01-01

    The temperature-dependent photoluminescence (PL) characteristics of zinc oxide (ZnO) embedded into the voids of synthetic opal were studied. ZnO was infiltrated into opal from aqueous solution with zinc nitrate precursor followed by thermal annealing. The PL spectra of the ZnO powder exhibit very high and broad emission peaks in the green region due to crystal defects, such as oxygen vacancies and zinc ion interstitials. In contrast to the PL spectra of ZnO powder, nanocrystals of ZnO embedded into the voids of FCC packed opal matrix exhibit dominant ultraviolet (UV)-blue and rapidly decreasing green PL emissions with decreasing temperature. The temperature-dependent PL characteristics show that the green band suppression in the ZnO nanocrystals is due to the influence of photonic crystal. The infiltration of nanoparticles into synthetic opal may be used for the fabrication of polycrystalline ZnO with dominant UV-blue PL. These results indicate that the luminescent materials embedded into photonic crystal may be promising for the fabrication of the RGB pixels in full-color displays

  7. Biocompatible and highly luminescent near-infrared CuInS₂/ZnS quantum dots embedded silica beads for cancer cell imaging.

    Science.gov (United States)

    Foda, Mohamed F; Huang, Liang; Shao, Feng; Han, He-You

    2014-02-12

    Bright and stable CuInS2/ZnS@SiO2 nanoparticles with near-infrared (NIR) emission were competently prepared by incorporating the as-prepared hydrophobic CuInS2/ZnS quantum dots (QDs) directly into lipophilic silane micelles and subsequently an exterior silica shell was formed. The obtained CuInS2/ZnS@SiO2 nanoparticles homogeneously comprised both single-core and multicore remarkable CuInS2/ZnS QDs, while the silica shell thickness could be controlled to within 5-10 nm and their overall size was 17-25 nm. Also, the functionalized CuInS2/ZnS QDs encapsulated in the silica spheres, expedited their bioconjugation with holo-Transferrin (Tf) for further cancer cell imaging. The CuInS2/ZnS@SiO2 nanoparticles not only showed a dominant NIR band-edge luminescence at 650-720 nm with a quantum yield (QY) between 30 and 50%, without a recognized photoluminescence (PL) red shift, but also exhibited excellent PL and colloidal stability in aqueous media. Impressively, the cytotoxicity studies revealed minor suppression on cell viability under both CuInS2/ZnS@SiO2 and CuInS2/ZnS@SiO2@Tf concentrations up to 1 mg/mL. The application in live-cell imaging revealed that the potential of CuInS2/ZnS QDs as biocompatible, robust, cadmium-free, and brilliant NIR emitters is considered promising for fluorescent labels.

  8. Increased viability and resilience of haemolymph cells in blue mussels following pre-treatment with acute high-dose gamma irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Jaeschke, B. [Stockholm University (Sweden)

    2014-07-01

    In an initial experiment, blue mussels (Mytilus edulis) were exposed to a range of acute high doses of gamma radiation in the laboratory. Haemolymph was extracted and the haemocytes (blood cells) were scored for cell viability (% living cells) under a microscope, directly after irradiation (0.04, 0.4 or 4 Gy) and again after a subsequent treatment with hydrogen peroxide in vitro (final H{sub 2}O{sub 2} conc.: 0.2 μM). Cell viability in controls (0 Gy) was approximately 100% and no cell death was observable from radiation exposure alone. When treated with H{sub 2}O{sub 2} a decrease in cell viability was seen across all treatments, however this decrease in viability was reduced with increasing radiation pre-treatment (0 Gy = 53%; 0.04 Gy = 66%; 0.4 Gy = 75%; 4 Gy = 83%). To investigate the mechanism for this therapeutic effect observed, the experiment was repeated. Using mussels from a different location, the same, but more extensive method of irradiation (0[control], 0.04, 0.4 Gy, 5 or 40 Gy) and H{sub 2}O{sub 2} treatment was used. Additional haemolymph sub-samples were taken for analysis of catalase concentration. In this second experiment, viability of cells from controls was only 62%, indicating the mussels were in a poorer condition than those of the previous experiment. The lowest level of radiation exposure (0.04 Gy) further decreased the viability (56%). However, at higher doses the viability was increased compared to control, which then gradually declined with increasing dose (0.4 Gy = 75%; 5 Gy = 72%; 40 Gy = 65%). Catalase analysis demonstrated a complimentary pattern of activity of the antioxidant in the haemolymph, directly correlating with radiation dose (0 Gy = 0.2 U; 0.04 Gy = 0.1 U; 0.4 Gy = 1.3 U; 5 Gy = 0.9 U; 40 Gy = 0.1 Gy). Treatment with H{sub 2}O{sub 2} decreased cell viability across all treatments, but no pattern between radiation treatments was discernable. The results indicate that an acute dose of radiation not only has negligible

  9. Blue Ribbon Panel Report

    Science.gov (United States)

    An NCI Cancer Currents blog by the NCI acting director thanking the cancer community for contributing to the Cancer Moonshot Blue Ribbon Panel report, which was presented to the National Cancer Advisory Board on September 7.

  10. Northeast Atlantic blue whiting

    OpenAIRE

    Heino, Mikko

    2010-01-01

    Heino, M. 2010. Northeast Atlantic blue whiting. In Life cycle spatial patterns of small pelagic fish in the Northeast Atlantic, pp. 59-64. Ed by P. Petitgas. ICES Cooperative Research Report 306. ICES, Copenhagen.

  11. New York Blue

    Data.gov (United States)

    Federal Laboratory Consortium — New York Blue is used cooperatively by the Laboratory and Stony Brook University as part of the New York Center for Computation Sciences. Ranked as the 28th fastest...

  12. Hybrid Monolith of Graphene/TEMPO-Oxidized Cellulose Nanofiber as Mechanically Robust, Highly Functional, and Recyclable Adsorbent of Methylene Blue Dye

    Directory of Open Access Journals (Sweden)

    Asif Hussain

    2018-01-01

    Full Text Available Herein we demonstrate first report on fabrication, characterization, and adsorptive appraisal of graphene/cellulose nanofibers (GO/CNFs monolith for methylene blue (MB dye. Series of hybrid monolith (GO/CNFs were assembled via urea assisted self-assembly method. Hybrid materials were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction patterns, Raman spectroscopy, elemental analysis, thermogravimetric curve analysis, specific surface area, surface charge density measurement, and compressional mechanical analysis. It was proposed that strong chemical interaction (mainly hydrogen bonding was responsible for the formation of hybrid assembly. GO/CNFs monolith showed mechanically robust architecture with tunable pore structure and surface properties. GO/CNFs adsorbent could completely remove trace to moderate concentrations of MB dye and follow pseudo-second-order kinetics model. Adsorption isotherm behaviors were found in the following order: Langmuir isotherm > Freundlich isotherm > Temkin isotherm model. Maximum adsorption capacity of 227.27 mg g−1 was achieved which is much higher than reported graphene based monoliths and magnetic adsorbent. Incorporation of nanocellulose follows exponential relationship with dye uptake capacities. High surface charge density and specific surface area were main dye adsorptive mechanism. Regeneration and recycling efficiency was achieved up to four consecutive cycles with cost-effective recollection and zero recontamination of treated water.

  13. Piezoelectrically-induced stress-luminescence phenomenon in CaAl{sub 2}O{sub 4}:Eu{sup 2+}

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Yongbin [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Wu, Zheng, E-mail: wuzheng@zjnu.cn [College of Geography and Environmental Sciences, Zhejiang Normal University, Jinhua 321004 (China); Jia, Yanmin, E-mail: ymjia@zjnu.edu.cn [Department of Physics, Zhejiang Normal University, Jinhua 321004 (China); Liu, Yongsheng [Department of Physics, Shanghai University of Electric Power, Shanghai 200090 (China)

    2015-10-15

    Piezoelectrically-induced stress-luminescence in the CaAl{sub 2}O{sub 4}:Eu{sup 2+} was investigated. Blue light that was visible to the naked eye could be observed in the dark when a pulse force of ∼7.7 kN was applied to the sample. The intensity of the stress-luminescence strongly depended on the magnitude of the applied force during a pulse cycle. The intensity decreased with repetitive application of pulse stress and was completely recovered after irradiation with ultraviolet light. It is suggested that the stress-luminescence effect in CaAl{sub 2}O{sub 4}:Eu{sup 2+} arises from the piezoelectrically-induced de-trapping of the charge carriers. A CaAl{sub 2}O{sub 4}:Eu{sup 2+} ceramic that exhibits a stress-luminescence effect has potential applications in smart stress optically-sensing devices. - Highlights: • The strong induced stress-luminescence in CaAl{sub 2}O{sub 4}:Eu{sup 2+} was observed. • The stress-luminescent intensity strongly depends on the magnitude of force. • The stress-luminescence could be completely recovered after the UV irradiation. • The strong stress-luminescent effect is potential in stress-light sensors.

  14. Polymethylmethacrylate-based luminescent solar concentrators with bottom-mounted solar cells

    International Nuclear Information System (INIS)

    Zhang, Yi; Sun, Song; Kang, Rui; Zhang, Jun; Zhang, Ningning; Yan, Wenhao; Xie, Wei; Ding, Jianjun; Bao, Jun; Gao, Chen

    2015-01-01

    Graphical abstract: - Highlights: • Bottom-mounted luminescent solar concentrators on dye-doped plates were studied. • The mechanism of transport process was proposed. • The fabricated luminescent solar concentrator achieved a gain of 1.38. • Power conversion efficiency of 5.03% was obtained with cell area coverage of 27%. • The lowest cost per watt of $1.89 was optimized with cell area coverage of 18%. - Abstract: Luminescent solar concentrators offer an attractive approach to concentrate sunlight economically without tracking, but the narrow absorption band of luminescent materials hinders their further development. This paper describes bottom-mounted luminescent solar concentrators on dye-doped polymethylmethacrylate plates that absorb not only the waveguided light but also the transmitted sunlight and partial fluorescent light in the escape cone. A series of bottom-mounted luminescent solar concentrators with size of 78 mm × 78 mm × 7 mm were fabricated and their gain and power conversion efficiency were investigated. The transport process of the waveguided light and the relationship between the bottom-mounted cells were studied to optimize the performance of the device. The bottom-mounted luminescent solar concentrator with cell area coverage of 9% displayed a cell gain of 1.38, to our best knowledge, which is the highest value for dye-doped polymethylmethacrylate plate luminescent solar concentrators. Power conversion efficiency as high as 5.03% was obtained with cell area coverage of 27%. Furthermore, the bottom-mounted luminescent solar concentrator was found to have a lowest cost per watt of $1.89 with cell area coverage of 18%. These results suggested that the fabricated bottom-mounted luminescent solar concentrator may have a potential in low-cost building integrated photovoltaic application

  15. Design, synthesis and luminescence properties of Ba2 YB2 O6 Cl- and Ba2 YB2 O6 F-based phosphors.

    Science.gov (United States)

    Chen, Wanping; Yang, Xin; Liu, Yan; Dai, Xiaoyan

    2015-05-01

    Using a high-temperature solid-state reaction, the chlorine in Ba2 YB2 O6 Cl is gradually replaced by F, and a new compound with the nominal chemical formula Ba2 YB2 O6 F and two phosphors doped with Ce(3+) and Eu(3+) , respectively, are obtained. X-Ray diffraction and photoluminescence spectroscopy are used to characterize the as-synthesized samples. The as-synthesized Ba2 YB2 O6 Cl exhibits bright blue emission in the spectral range ~ 330-410 nm with a maximum around 363 nm under X-ray or UV excitation. Ba2 YB2 O6 F:0.01Ce(3+) exhibits blue emission in the range ~ 340-570 nm with a maximum around 383 nm. Ba2 YB2 O6 F:0.01Eu(3+) exhibits a predominantly (5) D0 -(7)  F2 emission (~610 nm) and the relative intensities of the (5) D0 -(7)  F0,1,2 emissions are tunable under different wavelength UV excitation. The luminescence behaviors of the two phosphors are explained simply in terms of the host composition and site occupancy probability of Ce(3+) and Eu(3+) , respectively. The results indicate that these phosphors have potential application as a blue phosphor or as a red phosphor. Copyright © 2014 John Wiley & Sons, Ltd.

  16. Development of optically stimulated luminescence techniques using natural minerals and ceramics, and their application to retrospective dosimetry

    Energy Technology Data Exchange (ETDEWEB)

    Boetter-Jensen, L

    2000-09-01

    This thesis summarises research and development of optically stimulated luminescence (OSL) and its applications by the author at Risoe National Laboratory, up to 1999. These developments have been directed primarily at retrospective accident dosimetry and luminescence dating. Experimental investigations include the studies of OSL properties of the natural minerals quartz and feldspars and the artificial materials porcelain and aluminium oxide (Al{sub 2}O{sub 3}). Blue light emitting diodes and infrared laser diodes are shown to provide simple and practical alternatives to broad-band light and visible laser stimulation. The development of OSL apparatus designed for the rapid measurement of single grains of phosphors also opens up a new area of luminescence measurement, allowing the detailed examination of dose distributions within a multiple-grain sample. This is of particular importance to the studies of incompletely reset geological sediments, and to accident dosimetry measurements using unheated materials. Al{sub 2}O{sub 3}:C single crystals are tested as environmental OSL dosemeters for assessing both the natural background photon radiation dose rates in the field and the natural dose rates inside bricks collected for accident dose evaluation. Environmental doses of the order of few {mu}Gy are measured with high precision. UV photo-stimulated luminescence spectra obtained from porcelain samples are used to confirm that the main component responsible for the OSL signal from porcelain is Al{sub 2}O{sub 3}. OSL single-aliquot regenerative-dose (SAR) techniques are used with quartz extracted from Chernobyl bricks to determine the accrued dose after the accident. This has improved the measurement precision significantly, from about 5-6 % using traditional methods to now less than 2 %. Depth-dose profiles measured in Chernobyl bricks are compared with those obtained in the laboratory using different gamma sources and these comparisons show that the average energy of

  17. Development of optically stimulated luminescence techniques using natural minerals and ceramics, and their application to retrospective dosimetry

    International Nuclear Information System (INIS)

    Boetter-Jensen, L.

    2000-09-01

    This thesis summarises research and development of optically stimulated luminescence (OSL) and its applications by the author at Risoe National Laboratory, up to 1999. These developments have been directed primarily at retrospective accident dosimetry and luminescence dating. Experimental investigations include the studies of OSL properties of the natural minerals quartz and feldspars and the artificial materials porcelain and aluminium oxide (Al 2 O 3 ). Blue light emitting diodes and infrared laser diodes are shown to provide simple and practical alternatives to broad-band light and visible laser stimulation. The development of OSL apparatus designed for the rapid measurement of single grains of phosphors also opens up a new area of luminescence measurement, allowing the detailed examination of dose distributions within a multiple-grain sample. This is of particular importance to the studies of incompletely reset geological sediments, and to accident dosimetry measurements using unheated materials. Al 2 O 3 :C single crystals are tested as environmental OSL dosemeters for assessing both the natural background photon radiation dose rates in the field and the natural dose rates inside bricks collected for accident dose evaluation. Environmental doses of the order of few μGy are measured with high precision. UV photo-stimulated luminescence spectra obtained from porcelain samples are used to confirm that the main component responsible for the OSL signal from porcelain is Al 2 O 3 . OSL single-aliquot regenerative-dose (SAR) techniques are used with quartz extracted from Chernobyl bricks to determine the accrued dose after the accident. This has improved the measurement precision significantly, from about 5-6 % using traditional methods to now less than 2 %. Depth-dose profiles measured in Chernobyl bricks are compared with those obtained in the laboratory using different gamma sources and these comparisons show that the average energy of the accident radiation was

  18. Luminescence properties of Ca2 Ga2 SiO7 :RE phosphors for UV white-light-emitting diodes.

    Science.gov (United States)

    Jiao, Mengmeng; Lv, Wenzhen; Lü, Wei; Zhao, Qi; Shao, Baiqi; You, Hongpeng

    2015-03-16

    A series of Eu(2+) -, Ce(3+) -, and Tb(3+) -doped Ca2 Ga2 SiO7 phosphors is synthesized by using a high-temperature solid-state reaction. The powder X-ray diffraction and structure refinement data indicate that our prepared phosphors are single phased and the phosphor crystalizes in a tetrahedral system with the ${P\\bar 42m}$ (113) space group. The Eu(2+) - and Ce(3+) -doped phosphors both have broad excitation bands, which match well with the UV light-emitting diodes chips. Under irradiation of λ=350 nm, Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) have green and blue emissions, respectively. Luminescence of Ca2 Ga2 SiO7 :Tb(3+) , Li(+) phosphor varies with the different Tb(3+) contents. The thermal stability and energy-migration mechanism of Ca2 Ga2 SiO7 :Eu(2+) are also studied. The investigation results indicate that the prepared Ca2 Ga2 SiO7 :Eu(2+) and Ca2 Ga2 SiO7 :Ce(3+) , Li(+) samples show potential as green and blue phosphors, respectively, for UV-excited white-light-emitting diodes. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Mechano-luminescence studies of nano ZnMgAl10O17:Eu phosphor under UV irradiation

    Science.gov (United States)

    Verma, Akshkumar; Verma, Ashish; Panda, Maheswar

    2018-05-01

    ZnMgAl10O17:Eu nano phosphors were prepared successfully, using the combustion route by employing urea as a fuel. The structural, and Morphological, properties were measured using x-ray diffraction (XRD) Scanning electron microscopy (SEM) transition electron microscopy. The BET surface area of sample were found to be of ˜13.92 m2/g. The ML (Mechano-luminescence) were measured to the home made instrument. The phosphor showed more strong and high ML intensity to the without UV irradiated material. Therefore ZnMgAl10O17:Eu2+ phosphor may use as a damage sensor and dosimetry material. The ML emission spectra of the Zn0.99MgAl10O17:Eu0.01 phosphor showed the characteristic Eu2+ emission peaks ˜453nm (blue) originating from the transitions 4f65d1→4f7, Therefore ZnMgAl10O17:Eu2+ phosphor may use as a blue phosphor material.

  20. Luminescence behaviour of beryl (aquamarine variety) from Turkey

    International Nuclear Information System (INIS)

    Katı, M.I.; Türemis, M.; Keskin, I.C.; Tastekin, B.; Kibar, R.; Çetin, A.; Can, N.

    2012-01-01

    Natural blue-green beryl from Turkey has been investigated using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and Cathodoluminescence (CL). Beryl has the chemical formula Be 3 Al 2 Si 6 O 18 and is hexagonal with space group P6/mcc. Chemical analyses of the beryl sample utilised inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for major oxides and trace elements. It shows that the beryl sample is rich in Cs (531 ppm) and contains low concentrations of transition-metal ions, in total 2.29 wt.% Fe, 269 ppm Mn, V<5 ppm and Cr 20 ppm. Ideas on the origin of the green colour of this mineral are presented. The CL spectrum of the bulk sample display intense broad band emission from ∼360 to ∼800 nm. - Highlights: ► Natural blue-green beryl from Turkey were investigated by SEM-EDS, XRD, CL. ► Luminescence behaviour of Natural blue-green beryl. ► The samples exhibit an intense broad band emission from ∼360 to ∼800 nm.

  1. Luminescence behaviour of beryl (aquamarine variety) from Turkey

    Energy Technology Data Exchange (ETDEWEB)

    Kat Latin-Small-Letter-Dotless-I , M.I.; Tueremis, M.; Keskin, I.C.; Tastekin, B.; Kibar, R.; Cetin, A. [Celal Bayar University, Faculty of Arts and Sciences, Physics Department, 45140 Manisa (Turkey); Can, N., E-mail: cannurdogan@yahoo.com [Celal Bayar University, Faculty of Arts and Sciences, Physics Department, 45140 Manisa (Turkey)

    2012-10-15

    Natural blue-green beryl from Turkey has been investigated using scanning electron microscopy-energy-dispersive spectroscopy (SEM-EDS), X-ray diffraction (XRD) and Cathodoluminescence (CL). Beryl has the chemical formula Be{sub 3}Al{sub 2}Si{sub 6}O{sub 18} and is hexagonal with space group P6/mcc. Chemical analyses of the beryl sample utilised inductively coupled plasma-atomic emission spectroscopy (ICP-AES) for major oxides and trace elements. It shows that the beryl sample is rich in Cs (531 ppm) and contains low concentrations of transition-metal ions, in total 2.29 wt.% Fe, 269 ppm Mn, V<5 ppm and Cr 20 ppm. Ideas on the origin of the green colour of this mineral are presented. The CL spectrum of the bulk sample display intense broad band emission from {approx}360 to {approx}800 nm. - Highlights: Black-Right-Pointing-Pointer Natural blue-green beryl from Turkey were investigated by SEM-EDS, XRD, CL. Black-Right-Pointing-Pointer Luminescence behaviour of Natural blue-green beryl. Black-Right-Pointing-Pointer The samples exhibit an intense broad band emission from {approx}360 to {approx}800 nm.

  2. A green emissive amorphous fac-Alq3 solid generated by grinding crystalline blue fac-Alq3 powder.

    Science.gov (United States)

    Bi, Hai; Chen, Dong; Li, Di; Yuan, Yang; Xia, Dandan; Zhang, Zuolun; Zhang, Hongyu; Wang, Yue

    2011-04-14

    A novel green emissive Alq(3) solid with a facial isomeric form has been obtained by grinding the typical blue luminescent fac-Alq(3) crystalline powder. This is the first report, to the best of our knowledge, that a fac-Alq(3) isomer emits green light.

  3. Self-reduction process and enhanced blue emission in SrAl{sub 2}Si{sub 2}O{sub 8}: Eu, Tb via electron transfer from Tb{sup 3+} to Eu{sup 3+}

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Hongwei; Wang, Lili; Li, Minhong; Ran, Weiguang; Deng, Zhihan; Houzong, Ruizhi; Shi, Jinsheng [Department of Chemistry and Pharmaceutical Science, Qingdao Agricultural University, Qingdao 266109, Shandong, (China)

    2017-06-15

    Eu, Tb co-doped SrAl{sub 2}Si{sub 2}O{sub 8} luminescent materials were synthesized via a high-temperature solid-state reaction. Excitation spectra of SrAl{sub 2}Si{sub 2}O{sub 8}: Eu{sup 2+} gives two broad excitation bands maximizing at 270 and 330 nm, resulting from splitting Eu{sup 2+} energy levels in octahedral crystal field. Eu single doped SrAl{sub 2}Si{sub 2}O{sub 8} luminescent material exhibits two emission bands at about 406 and 616 nm. Intensity of the blue emission from Eu{sup 2+} is always strong, compared with that of the red emission band of Eu{sup 3+}. Reduction from Eu{sup 3+} to Eu{sup 2+} can be explained with the model of charge compensation. Blue emission in SrAl{sub 2}Si{sub 2}O{sub 8}: xEu was strengthened after incorporation of Tb, which can be explained by electron transfer from Tb{sup 3+} to Eu{sup 3+} (Tb{sup 3+} + Eu{sup 3+} → Tb{sup 4+} + Eu{sup 2+}). Under 230 nm excitation, intensity of Tb{sup 3+} emission was nearly unchanged and that of Eu{sup 2+} was increased, obviously due to the delivery of more electrons to Eu{sup 3+}. The strongest emission of Eu{sup 2+} in 0.09Eu/0.06Tb co-doped SrAl{sub 2}Si{sub 2}O{sub 8} and excited at 270 and 330 nm was remarkably enhanced by about four times compared to that of 0.15Eu Single doped SrAl{sub 2}Si{sub 2}O{sub 8}. All of the results indicate that SrAl{sub 2}Si{sub 2}O{sub 8}:xEu, yTb are potential blue emitting luminescent materials for UV-LEDs. More importantly, this research may provide a new perspective in designing broad band blue luminescent materials. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Violet-blue photoluminescence from Si nanoparticles with zinc-blende structure synthesized by laser ablation in liquids

    Directory of Open Access Journals (Sweden)

    P. Liu

    2013-02-01

    Full Text Available Violet-blue luminescence from Si nanostructures has been widely investigated, because of its potential use in optoelectronic and bioimaging devices. However, the emission mechanism in multiform Si nanomaterials remains unclear. In this contribution, Si nanocrystals (NCs with zincblende structure and visible violet-blue emission are prepared by electric field assisted laser ablation in liquids. While subsequent annealing of the Si NCs weakens their blue emission dramatically. We investigate the origin of the violet-blue emission by monitoring crystal structure transitions and photoluminescence during different treatments of the Si NCs. The results indicate that the violet-blue emission cannot simply be ascribed to quantum confinement effects or the presence of general surface states on the Si NCs. Instead, we propose that excitons are formed within the Si NCs by direct transitions at Γ or X points, which can be induced during the formation of the zincblende structure, and are a most possible origin of the violet-blue luminescence. Furthermore, defects in the metastable Si NCs are also expected to play an important role in violet-blue emission. This study not only gives clear and general insight into the physical origins of violet-blue emission from Si NCs, it also provides useful information for designing optoelectronic devices based on Si NCs.

  5. High electron mobility through the edge states in random networks of c-axis oriented wedge-shaped GaN nanowalls grown by molecular beam epitaxy

    International Nuclear Information System (INIS)

    Bhasker, H. P.; Dhar, S.; Sain, A.; Kesaria, Manoj; Shivaprasad, S. M.

    2012-01-01

    Transport and optical properties of random networks of c-axis oriented wedge-shaped GaN nanowalls grown spontaneously on c-plane sapphire substrates through molecular beam epitaxy are investigated. Our study suggests a one dimensional confinement of carriers at the top edges of these connected nanowalls, which results in a blue shift of the band edge luminescence, a reduction of the exciton-phonon coupling, and an enhancement of the exciton binding energy. Not only that, the yellow luminescence in these samples is found to be completely suppressed even at room temperature. All these changes are highly desirable for the enhancement of the luminescence efficiency of the material. More interestingly, the electron mobility through the network is found to be significantly higher than that is typically observed for GaN epitaxial films. This dramatic improvement is attributed to the transport of electrons through the edge states formed at the top edges of the nanowalls.

  6. Highly efficient Fenton and enzyme-mimetic activities of NH2-MIL-88B(Fe) metal organic framework for methylene blue degradation.

    Science.gov (United States)

    He, Jianchuan; Zhang, Yao; Zhang, Xiaodan; Huang, Yuming

    2018-03-26

    Here, we show that NH 2 -MIL-88B(Fe) can be used as a peroxidase-like catalyst for Fenton-like degradation of methylene blue (MB) in water. The iron-based NH 2 -MIL-88B(Fe) metal organic framework (MOF) was synthesized by a facile and rapid microwave heating method. It was characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, powder X-ray diffraction, and the Brunauer-Emmett-Teller method. The NH 2 -MIL-88B(Fe) MOF possesses intrinsic oxidase-like and peroxidase-like activities. The reaction parameters that affect MB degradation were investigated, including the solution pH, NH 2 -MIL-88B(Fe) MOF and H 2 O 2 concentrations, and temperature. The results show that the NH 2 -MIL-88B(Fe) MOF exhibits a wide working pH range (pH 3.0-11.0), temperature tolerance, and good recyclability for MB removal. Under the optimal conditions, complete removal of MB was achieved within 45 min. In addition, removal of MB was above 80% after five cycles, showing the good recyclability of NH 2 -MIL-88B(Fe). The NH 2 -MIL-88B(Fe) MOF has the features of easy preparation, high efficiency, and good recyclability for MB removal in a wide pH range. Electron spin resonance and fluorescence probe results suggest the involvement of hydroxyl radicals in MB degradation. These findings provide new insight into the application of high-efficient MOF-based Fenton-like catalysts for water purification.

  7. Blue Light Emitting Diodes for Optical Stimulation of Quartz in Retrospective Dosimetry and Dating (invited paper)

    International Nuclear Information System (INIS)

    Botter-Jensen, L.; Duller, G.A.T.; Murray, A.S.; Banerjee, D.

    1999-01-01

    Recently developed blue light emitting diodes (LEDs) for the optical stimulation of quartz for use in routine optically stimulated luminescence (OSL) dating and retrospective dosimetry have been tested. For similar power densities, it was found that the higher energy light provided by the blue LEDs (470 nm) gives order of magnitude greater rate of stimulation in quartz than that from conventional blue-green light filtered from a halogen lamp. A practical blue LED OSL configuration is described. From comparisons of OSL decay curves produced by green and blue light sources, and by examination of the dependence of the blue LED OSL on preheat temperature, it is deduced that there is no evidence that the blue LEDs stimulate deep traps in a different manner from broadband filtered light. It is concluded that blue LEDs offer a practical alternative to existing stimulation sources. They have the significant advantages that the life-time is indefinite, and the output can be controlled electronically; this allows the power to be readily controlled by software. Unlike a filtered light source, there are no electromechanical parts, and the switch on/off times are about 10 times faster than a shutter. Finally, preliminary results from ramping the blue light power output with time are demonstrated. It is shown that this technique enables the separation of OSL components with differing stimulation rates. (author)

  8. Nervous control of photophores in luminescent fishes.

    Science.gov (United States)

    Zaccone, Giacomo; Abelli, Luigi; Salpietro, Lorenza; Zaccone, Daniele; Macrì, Battesimo; Marino, Fabio

    2011-07-01

    Functional studies of the autonomic innervation in the photophores of luminescent fishes are scarce. The majority of studies have involved either the stimulation of isolated photophores or the modulatory effects of adrenaline-induced light emission. The fish skin is a highly complex organ that performs a wide variety of physiological processes and receives extensive nervous innervations. The latter includes autonomic nerve fibers of spinal sympathetic origin having a secretomotor function. More recent evidence indicates that neuropeptide-containing nerve fibers, such as those that express tachykinin and its NK1 receptor, neuropeptide Y, or nitric oxide, may also play an important role in the nervous control of photophores. There is no anatomical evidence that shows that nNOS positive (nitrergic) neurons form a population distinct from the secretomotor neurons with perikarya in the sympathetic ganglia. The distribution and function of the nitrergic nerves in the luminous cells, however, is less clear. It is likely that the chemical properties of the sympathetic postganglionic neurons in the ganglia of luminescent fishes are target-specific, such as observed in mammals. Copyright © 2010 Elsevier GmbH. All rights reserved.

  9. The luminescent chamber and its use in high-energy physics experiments; La chambre a luminescence: son emploi dans les experiences de physique des hautes energies; Lyuminestsentnaya kamera i ee ispol'zovanie v ehksperimentakh, provodimykh v fizike vysokikh ehnergij; La camara luminiscente y su empleo en experimentos de fisica de elevada energia

    Energy Technology Data Exchange (ETDEWEB)

    Jones, L W; Perl, M L [Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI (United States); Lawrence Radiation Laboratory, University of California, Berkeley, CA (United States)

    1962-04-15

    A luminescent chamber has been employed for the first time in experiments in high-energy particle physics. At the Bevatron of the Lawrence Radiation Laboratory, particle tracks in activated sodium-iodide crystals were photographed using a cascade system of three-image intensifier tubes. In one experiment, elastic pion-proton scattering was studied using two arrays of scintillator, each 20 cm long, one to observe the scattered pion and the other the recoil proton from a liquid hydrogen target. Scintillation counters selected only nearly-coplanar events to be recorded; however the final criteria for elastic scattering were the kinematics of the recorded tracks. About 1000 elastic events were photographed at each of three incident pion moments up to 2.5 MeV/c. In a second experiment a single-scintillator array 10 x 10 x 20 cm{sup 3} was used to observe stopping recoil protons from inelastic pion scattering (single pion production) at three incident pion momenta. Again several thousand events were recorded. The range and angle of the recoil proton uniquely determined the momentum transfer and the centre-of-mass energy of the di-pion system which were the relevant kinematical parameters in this problem. In these experiments post-event triggering and five-microsecond time-resolution were achieved by gating the second image tube on a signal from the scintillation-counter electronics. The design and successful execution of these experiments are discussed in this paper, with particular reference to the relevant details of the image tubes, the scintillation counters and the electronic systems. Experience has also been gained in the analysis of the track photographs, particularly regarding the accuracy obtainable and reliability of the physics thus obtained. In conclusion, the future evolution of the luminescent chamber is explored, considering the image intensifier tubes and scintillators under current development. The role of the luminescent chamber in future highenergy

  10. Blue-emitting dinuclear N-heterocyclic dicarbene gold(I) complex featuring a nearly unit quantum yield

    KAUST Repository

    Baron, Marco

    2012-02-06

    Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au 2(RIm-Y-ImR) 2](PF 6) 2 (R = Me, Cy; Y = (CH 2) 1-4, o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me, Y = (CH 2) 3 exhibit an intense blue emission (λ max = 450 nm) with a high quantum yield (Φ em = 0.96). The X-ray crystal structure of this complex is characterized by a rather short intramolecular Au•••Au distance (3.272 Ǻ). Time dependent density functional theory (TDDFT) calculations have been used to calculate the UV/vis properties of the ground state as well as of the first excited state of the complex, the latter featuring a significantly shorter Au•••Au distance. © 2012 American Chemical Society.

  11. Blue-emitting dinuclear N-heterocyclic dicarbene gold(I) complex featuring a nearly unit quantum yield

    KAUST Repository

    Baron, Marco; Tubaro, Cristina; Biffis, Andrea; Basato, Marino; Graiff, Claudia; Poater, Albert; Cavallo, Luigi; Armaroli, Nicola; Accorsi, Gianluca

    2012-01-01

    Dinuclear N-heterocyclic dicarbene gold(I) complexes of general formula [Au 2(RIm-Y-ImR) 2](PF 6) 2 (R = Me, Cy; Y = (CH 2) 1-4, o-xylylene, m-xylylene) have been synthesized and screened for their luminescence properties. All the complexes are weakly emissive in solution whereas in the solid state some of them show significant luminescence intensities. In particular, crystals or powders of the complex with R = Me, Y = (CH 2) 3 exhibit an intense blue emission (λ max = 450 nm) with a high quantum yield (Φ em = 0.96). The X-ray crystal structure of this complex is characterized by a rather short intramolecular Au•••Au distance (3.272 Ǻ). Time dependent density functional theory (TDDFT) calculations have been used to calculate the UV/vis properties of the ground state as well as of the first excited state of the complex, the latter featuring a significantly shorter Au•••Au distance. © 2012 American Chemical Society.

  12. Luminescence of LiH(D):Ru monocrystals

    International Nuclear Information System (INIS)

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

    1993-01-01

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

  13. Luminescence centers in bismuth orthogermanate

    International Nuclear Information System (INIS)

    Bordun, O.M.

    2001-01-01

    The luminescence and photoexcitation spectra of single crystals,ceramics,and thin films of Bi 4 Ce 3 O 1 2 are studied.The decomposition of the luminescence spectra into elementary components by the Alentsev-Fock method showed that they consist of three bands with maxima at 2.7,2.4,and 2.05 eV.The bands with maxima at 2.7 and 2.4 eV are assigned to the emission of self-trapped Frenkel excitons describing the excited state of a (BiO 6 ) 9- molecular ion. Emission bands with maxima at 2.0 5 eV are assigned to recombination on traps caused by structural defects

  14. X-ray luminescent glasses

    International Nuclear Information System (INIS)

    Takahashi, T.; Yamada, O.

    1981-01-01

    X-ray luminescent glasses comprising a divalent cation such as an alkaline earth metal or other divalent cations such as pb, cd, or zn, and certain rare earth metaphosphates are suitable as vitreous, x-ray phosphors or x-ray luminescent glass fibers in an x-ray intensifying screen. The glasses have the composition n(Mo X p2o5)((1-y)tb2o3 X yce2o3 X 3p2o5) wherein N is greater than zero but less than or equal to 16, M is an alkaline earth metal or other divalent cation such as pb, cd, or zn, and Y is greater than or equal to zero but less than one

  15. Dyes adsorption blue vegetable and blue watercolor by natural zeolites modified with surfactants

    International Nuclear Information System (INIS)

    Jardon S, C. C.; Olguin G, M. T.; Diaz N, M. C.

    2009-01-01

    In this work was carried out the dyes removal blue vegetable and blue watercolor of aqueous solutions, to 20 C, at different times and using a zeolite mineral of Parral (Chihuahua, Mexico) modified with hexadecyl trimethyl ammonium bromide or dodecyl trimethyl ammonium bromide. The zeolite was characterized before and after of its adaptation with NaCl and later with HDTMABr and DTMABr. For the materials characterization were used the scanning electron microscopy of high vacuum; elementary microanalysis by X-ray spectroscopy of dispersed energy and X-ray diffraction techniques. It was found that the surfactant type absorbed in the zeolite material influences on the adsorption process of the blue dye. Likewise, the chemical structure between the vegetable blue dye and the blue watercolor, determines the efficiency of the color removal of the water, by the zeolites modified with the surfactants. (Author)

  16. Apparatus for reducing solvent luminescence background emissions

    Energy Technology Data Exchange (ETDEWEB)

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

    1998-01-01

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

  17. Modern luminescence spectroscopy of minerals and materials

    CERN Document Server

    Gaft, Michael; Panczer, Gerard

    2005-01-01

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

  18. High quality diet improves lipid metabolic profile and breeding performance in the blue-footed booby, a long-lived seabird.

    Directory of Open Access Journals (Sweden)

    Erick González-Medina

    Full Text Available Understanding the role of diet in the physiological condition of adults during reproduction and hence its effect on reproductive performance is fundamental to understand reproductive strategies in long-lived animals. In birds, little is known about the influence of the quality of food consumed at the beginning of the reproductive period and its short-term effects on reproductive performance. To assess the role of diet in the physiological condition of female blue-footed booby, Sula nebouxii (BFBO, during reproduction we evaluated whether individual differences in diet (assessed by using δ13C and δ15N values of whole blood from female birds and muscle tissue of the principal prey species prior to egg laying and during incubation influenced their lipid metabolic profile (measured as triglyceride levels and C:N ratio and their reproductive performance (defined by laying date, clutch size and hatching success. Females with higher δ15N values in their blood during the courtship and incubation periods had a higher lipid metabolic profile, earlier laying date, greater clutch size (2-3 eggs and higher hatching success. Females that laid earlier and more eggs (2-3 eggs consumed more Pacific anchoveta (Cetengraulis mysticetus and Pacific thread herring (Opisthonema libertate than did other females. These two prey species also had high amounts of lipids (C:N ratio and caloric content (Kcal/g fresh weight. The quality of food consumed by females at the beginning of reproduction affected their physiological condition, as well as their short-term reproductive performance. Our work emphasizes the importance of determining the influence of food quality during reproduction to understand the reproductive decisions and consequences in long-lived animals.

  19. Handbook of luminescent semiconductor materials

    CERN Document Server

    Bergman, Leah

    2011-01-01

    Photoluminescence spectroscopy is an important approach for examining the optical interactions in semiconductors and optical devices with the goal of gaining insight into material properties. With contributions from researchers at the forefront of this field, Handbook of Luminescent Semiconductor Materials explores the use of this technique to study semiconductor materials in a variety of applications, including solid-state lighting, solar energy conversion, optical devices, and biological imaging. After introducing basic semiconductor theory and photoluminescence principles, the book focuses

  20. Luminescence studies on phosphor screens

    International Nuclear Information System (INIS)

    Panayiotakis, G.; Nomikos, C.; Bakas, A.; Proimos, B.

    1994-01-01

    We report our results on x-ray phosphor screens prepared of some new materials focusing attention on their efficiency under fluoroscopy conditions, on optimization conditions and on comparisons among the various materials. All data are presented in absolute values. A theoretical model is presented, that takes into account the granular structure of the screens, permitting the explanation and prediction of the luminescence properties of the screens. (authors)