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Sample records for eu tm yb

  1. White light upconversion in Yb-sensitized (Tm, Ho)-doped KLu(WO4)2 nanocrystals: the effect of Eu incorporation.

    PubMed

    Barrera, E W; Pujol, M C; Carvajal, J J; Mateos, X; Solé, Rosa; Massons, J; Speghini, A; Bettinelli, M; Cascales, C; Aguiló, M; Díaz, F

    2014-01-28

    Monoclinic Yb-sensitized (Tm, Ho)-doped KLu(WO4)2 nanocrystals of ~100 nm size have been synthesized by the modified Pechini sol-gel method. Their diode laser near-infrared (~980 nm) excited upconversion emission properties have been characterized at power densities in the range 30-355 W cm(-2). Bright white light composed of blue ~475 nm, green ~540 nm, and red ~650 nm emissions, corresponding to Tm(3+ 1)G4 → (3)H6, Ho(3+ 5)S2, (5)F4 → (5)I8, and Ho(3+ 5)F5 → (5)I8 electronic transitions, respectively, was generated by adjusting the Yb, Tm, and Ho contents in KLu(WO4)2 nanocrystalline samples. Chromaticity coordinates of the emitted white light can be tuned by modifying the excitation power density. The effect of Tm and Ho on the luminescence dynamics has been described by analyzing the upconverted emission intensity dependence on the excitation power, as well as from Stokes and decay time measurements. The effect on upconversion properties of further codoping with Eu in these (Tm, Ho, Yb)-doped KLu(WO4)2 nanocrystals has also been studied.

  2. Structural and optical properties of lanthanide oxides grown by atomic layer deposition (Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb).

    PubMed

    Hansen, Per-Anders; Fjellvåg, Helmer; Finstad, Terje; Nilsen, Ola

    2013-08-14

    Ln2O3 thin films with optically active f-electrons (Ln = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Tm, Yb) have been grown on Si(100) and soda lime glass substrates by atomic layer deposition (ALD) using Ln(thd)3 (Hthd = 2,2,6,6-tetramethyl-3,5-heptanedione) and ozone as precursors. The temperature range for depositions was 200-400 °C. Growth rates were measured by spectroscopic ellipsometry and a region with a constant growth rate (ALD window) was found for Ln = Ho and Tm. All the compounds are grown as amorphous films at low temperatures, whereas crystalline films (cubic C-Ln2O3) are obtained above a certain temperature ranging from 300 to 250 °C for Nd2O3 to Yb2O3, respectively. AFM studies show that the films were smooth (rms < 1 nm) except for depositions at the highest temperatures. The refractive index was measured by spectroscopic ellipsometry and was found to depend on the deposition temperature. Optical absorption measurements show that the absorption from the f-f transitions depends strongly on the crystallinity of the material. The clear correlation between the degree of crystallinity, optical absorptions and refractive indices is discussed.

  3. Large-scale synthesis of Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres and their photoluminescence properties

    SciTech Connect

    Gao, Yu; Gong, Jian; Fan, Miaomiao; Fang, Qinghong; Wang, Na; Han, Wenchi; Xu, Zhenhe

    2012-12-15

    Graphical abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. Display Omitted Highlights: ► Lu{sub 2}O{sub 3}:Ln{sup 3+} microspheres were prepared by a precipitation followed by a calcination process. ► Lu{sub 2}O{sub 3}:Eu{sup 3+}/Tb{sup 3+} samples exhibit respective red or green emissions. ► Lu{sub 2}O{sub 3}:Yb{sup 3+}/Er{sup 3+}/Tm{sup 3+}/Ho{sup 3+} exhibit emissions of green, blue, yellow-green, respectively. ► These finding may find potential applications in bioanalysis and field emission displays. -- Abstract: In this work, multicolor and monodisperse Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+}, Tb{sup 3+}, Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) microspheres were prepared by a homogeneous precipitation method followed by a subsequent calcination process. X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), thermogravimetric analysis (TGA), scanning electron microscopy (SEM), transmission electron microscopy (TEM), photoluminescence (PL) spectra, and cathodoluminescence (CL) spectra were employed to characterize the samples. Upon ultraviolet and low-voltage electron beams excitation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Eu{sup 3+} and Tb{sup 3+}) samples exhibit respective bright red (Eu{sup 3+}, {sup 5}D{sub 0} → {sup 7}F{sub 2}) and green (Tb{sup 3+}, {sup 5}D{sub 4} → {sup 7}F{sub 5}) down-conversion (DC) emissions. Under 980 nm NIR irradiation, Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln{sup 3+} = Yb{sup 3+}/Er{sup 3+}, Yb{sup 3+}/Tm{sup 3+}, and Yb{sup 3+}/Ho{sup 3+}) exhibit characteristic up-conversion (UC) emissions of green (Er{sup 3+}, {sup 4}S{sub 3/2}, {sup 2}H{sub 11/2} → {sup 4}I{sub 15/2}), blue (Tm{sup 3+}, {sup 1}G{sub 4} → {sup

  4. Controlled synthesis and luminescence properties of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, Dy, Yb/Er, Yb/Tm, and Yb/Ho) phosphors by hydrothermal method versus pulsed laser deposition

    NASA Astrophysics Data System (ADS)

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Chandramohan, Rathinam

    2016-01-01

    Herein, we report on rare-earth (RE) activated Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, Dy, Yb/Er, Yb/Ho, and Yb/Tm) phosphors synthesized using a surfactant-mediated hydrothermal route. Timedependent experiments were performed, and the morphological evolution of the phosphors was studied. From prepared powder samples of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu and Yb/Er), nano-sized thin phosphor films were grown using pulsed laser deposition (PLD). The surface topography of the as-grown thin phosphor films was analyzed. The asprepared phosphors were characterized by structural and optical studies. The powder phosphor exhibited bi pyramid-like micro-architectures. Structural studies indicated that Ca0.5Y1-x(MoO4)2 possesses the scheelite tetragonal crystal structure. The down-conversion luminescence of Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Eu, Pr, Sm, Tb, and Dy) as powder phosphors and Eu3+ doped Ca0.5Y1-x(MoO4)2 thin phosphor film were studied. Upon irradiation with a 980 nm laser, the Ca0.5Y1-x(MoO4)2: xRE3+ (RE = Yb/Er, Yb/Ho, and Yb/Tm) powder phosphors and Ca0.5Y1-x(MoO4)2:xRE3+ (RE = Yb/Er) thin phosphor film showed intense up-converted visible emissions in green, yellow, and blue regions. The fluorescence decay time and color co-ordinates were determined for all synthesized phosphors. From the obtained results, the prepared powder and thin film phosphors are suggested to be suitable candidates for display and electro-luminescence applications. [Figure not available: see fulltext.

  5. Valence changes in TmSe by alloying with TmTe and EuSe

    NASA Astrophysics Data System (ADS)

    Batlogg, B.

    1981-01-01

    The valence of the Tm ions in mixed-valent TmSe has been influenced by alloying with TmTe and EuSe in order to study the interaction between intermediate-valent rare-earth ions as a function of the degree of valence mixing. Magnetic, elastic, electrical, and optical properties have been measured on TmSe1-xTex crystals for seven distinct compositions. The degree of valence mixing is increased as Se is replaced by Te up to ~ 20% and the material remains metallic. Whereas TmSe orders metamagnetically (TN=3 K), the Te-containing samples are spontaneously magnetized below 3-5 K. This increasing strength of the ferromagnetic interactions, accompanying the increase of valence mixing, is consistent with the model of a double exchange coupling of mixed-valent Tm ions. TmSe1-xTex with x>=0.5 is semiconducting, the Tm ions are divalent and the overall electronic structure is similar to the ones of the Sm, Eu, and Yb monochalcogenides. The only peculiarities are the narrow energy gaps (0.2 to 0.35 eV) which require pressures of some 20 to 30 kbar to be closed. The magnetic properties are dominated by the crystal-field-split 2F72 ground state, leading to ordering temperatures well below 1 K. As Eu replaces Tm in TmSe, it is divalent because of its highly stable 4f7 shell, whereas the Tm2+ 4f13 and Tm3+ 4f12 5d configurations are nearly degenerate: in Tm0.5Eu0.5Se they are separated by an energy gap of only 0.1 eV, which can be driven to zero with moderate external pressure (15 kbar). In the metallic Tm0.83Eu0.17Se, the Tm ions are of predominantly inhomogeneously mixed-valent character since the Eu ions, being larger in volume are thought to give rise to local deformations of the lattice.

  6. Spectral and Luminescent Properties of Oxyfluoride Glasses Codoped with (Yb3+, Eu3+) and (Yb3+, Tb3+)

    NASA Astrophysics Data System (ADS)

    Vilejshikova, E. V.; Loiko, P. A.; Rachkovskaya, G. E.; Zakharevich, G. B.; Yumashev, K. V.

    2016-09-01

    The spectral and luminescent properties of SiO2-PbO-PbF2-CdF2 oxyfl uoride glasses doped with Yb3+, Eu3+, and Tb3+ were investigated. The lifetime τ( 5D0) of Eu3+ in glasses doped with Eu2O3 was 1.73 ms; τ( 5D4) of Tb3+, 2.25 ms. Intense red and green up-conversion luminescence due to cooperative energy transfer from Yb3+—Yb3+ pairs to Eu3+ and Tb3+ was observed for glasses codoped with (Yb3+, Eu3+) and (Yb3+, Tb3+) upon excitation at 960 nm into the Yb3+ absorption band. Down-conversion luminescence of Yb3+ ions in the vicinity of ~1 μm was detected upon excitation by UV light of wavelength 355 nm.

  7. Spectroscopic and laser characterization of Yb,Tm:KLu(WO4)2 crystal

    NASA Astrophysics Data System (ADS)

    Loiko, P. A.; Serres, J. M.; Mateos, X.; Demesh, M. P.; Yasukevich, A. S.; Yumashev, K. V.; Petrov, V.; Griebner, U.; Aguiló, M.; Díaz, F.

    2016-01-01

    We report on a comprehensive spectroscopic and laser characterization of monoclinic Yb,Tm:KLu(WO4)2 crystals. Stimulated-emission cross-section spectra corresponding to the 3F4 → 3H6 transition of Tm3+ ions are determined. The radiative lifetime of the 3F4 state of Tm3+ ions is 0.82 ms. The maximum Yb3+ → Tm3+ energy transfer efficiency is 83.9% for 5 at.% Yb - 8 at.% Tm doping. The fractional heat loading for Yb,Tm:KLu(WO4)2 is 0.45 ± 0.05. Using a hemispherical cavity and 5 at.% Yb - 6 at.% Tm doped crystal, a maximum CW power of 227 mW is achieved at 1.983-2.011 μm with a maximum slope efficiency η = 14%. In the microchip laser set-up, the highest slope efficiency is 20% for a 5 at.% Yb- 8 at.% Tm doped crystal with a maximum output power of 201 mW at 1.99-2.007 μm. Operation of Yb,Tm:KLu(WO4)2 as a vibronic laser emitting at 2.081-2.093 μm is also demonstrated.

  8. Emission spectroscopy and energy transfer in Tm 3+, Tm 3+-Ho 3+ and Tm 3+-Yb 3+ doped tellurite fibers

    NASA Astrophysics Data System (ADS)

    Richards, Billy; Shen, Shaoxiong; Jha, Animesh

    2006-09-01

    This paper examines the steady state and time resolved emission spectroscopy of Tm 3+ doped and Tm 3+-Ho 3+, Tm 3+-Yb 3+ co-doped tellurite fibers for mid-IR fiber laser design which find applications for lidar. These doped fibers show promising properties for compact and tunable laser sources in the visible and mid-IR when pumped at 800 nm, 980 nm and 1480 nm which can be used for remote chemical sensing and atmospheric monitoring. Tellurite glass has a lower cut-off phonon energy than silica glass and is more environmentally stable than fluoride glass, and coupling these properties with its high rare-earth ion solubility and high refractive index make this glass a very interesting material in which to study the fluorescence properties of these rare earth ions. We have measured the mid-IR fluorescence properties in varying lengths of multi-mode and single-mode fiber for the 3H 4- 3H 6 (~1.85 μm), 3H 4- 3F 4 (~1.46 μm) transitions in Tm 3+ and the 5I 7- 5I 8 (~2.05 μm) transition in Ho 3+. We have also measured the visible emission from these fibers due to excited state absorption (ESA) as there is blue and green emission in Tm 3+ and Tm 3+-Ho 3+ doped fibers respectively when pumped at 800 nm, and strong red and blue emission in the Tm 3+-Yb 3+ when pumped at 980 nm. These results in fiber are compared to bulk glass results and are used to describe the pumping schemes and energy transfer mechanisms of these rare earth ions in tellurite fiber.

  9. Infrared luminescence of Tm{sup 3+}/Yb{sup 3+} codoped lanthanum aluminum germanate glasses

    SciTech Connect

    Zhang Qiang; Zhang Guang; Chen Guorong; Qiu Jianrong; Chen Danping

    2010-01-15

    Tm{sup 3+} doped and Tm{sup 3+}/Yb{sup 3+} codoped lanthanum aluminum germanate (LAG) glasses are prepared by melt-quenching method and characterized optically. Based on the measurement of absorption spectrum, Judd-Ofelt intensity parameters ({Omega}{sub 2},{Omega}{sub 4},{Omega}{sub 6}) are calculated. The radiation emission rates, branching ratios, and lifetimes of Tm{sup 3+} are calculated to evaluate the spectroscopic properties of Tm{sup 3+} in LAG glass. The infrared emission properties of the samples are investigated and the results show that the 1.8 {mu}m emission can be greatly enhanced by adding proper amount of Yb{sup 3+} under the excitation of 980 nm. The energy transfer processes of Yb{sup 3+}-Yb{sup 3+} and Yb{sup 3+}-Tm{sup 3+} are analyzed, and the results show that Yb{sup 3+} ions can transfer their energy to Tm{sup 3+} ions with high efficiency and large energy transfer coefficient.

  10. Up-conversion emission in KGd(WO 4 ) 2 single crystals triply-doped with Er 3+ /Yb 3+ /Tm 3+ , Tb 3+ /Yb 3+ /Tm 3+ and Pr 3+ /Yb 3+ /Tm 3+ ions

    NASA Astrophysics Data System (ADS)

    Kasprowicz, D.; Brik, M. G.; Majchrowski, A.; Michalski, E.; Głuchowski, P.

    2011-09-01

    Triply-doped single crystals KGd(WO 4) 2:Er 3+/Yb 3+/Tm 3+, KGd(WO 4) 2:Tb 3+/Yb 3+/Tm 3+ and KGd(WO 4) 2:Pr 3+/Yb 3+/Tm 3+ were grown by the Top Seeded Solution Growth (TSSG) method, with an aim of getting efficient up-converted multicolored luminescence, which subsequently can be used for generation of white light. Such an aim determined the choice of the triply doped compounds: excitation of the Yb 3+ ions in the infrared spectral region is followed by red, green and blue emission from other dopants. It was shown that all these systems exhibit multicolor up-conversion fluorescence under 980 nm laser irradiation. Detailed spectroscopic studies of their absorption and luminescence spectra were performed. From the analysis of the dependence of the intensity of fluorescence on the excitation power the conclusion was made about significant role played by the host's conduction band and other possible defects of the KGd(WO 4) 2 crystal lattice in the up-conversion processes.

  11. Near-infrared Downconversion in LuPO4: Tm3+, Yb3+ Phosphors.

    PubMed

    Li, Li; Wang, Yongjie; Shen, Jun; Chang, Wenxuan; Jin, Tianting; Wei, Xiantao; Tian, Ya

    2016-04-01

    Tm3+ and Yb3+ codoped LuPO4 phosphors were synthesized by the reverse-strike co-precipitation method. The obtained LuPO4:Tm3+,Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra, and decay lifetime to understand the observed near-infrared downconversion (DC) phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of LuPO4 and exhibit good crystallinity. The experimental results showed that the strong visible emission around 649 nm from Tm3+(1G4 --> 3F4) and near-infrared (NIR) emission around 1003 nm from Yb3+(2F5/2 --> 2F7/2) of LuPO4:Tm3+,Yb3+ phosphors were observed under 468 nm excitation, respectively. The Yb3+ concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches 30 mol%. The DC mechanism is also discussed in detail. PMID:27451658

  12. Near-infrared Downconversion in LuPO4: Tm3+, Yb3+ Phosphors.

    PubMed

    Li, Li; Wang, Yongjie; Shen, Jun; Chang, Wenxuan; Jin, Tianting; Wei, Xiantao; Tian, Ya

    2016-04-01

    Tm3+ and Yb3+ codoped LuPO4 phosphors were synthesized by the reverse-strike co-precipitation method. The obtained LuPO4:Tm3+,Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra, and decay lifetime to understand the observed near-infrared downconversion (DC) phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of LuPO4 and exhibit good crystallinity. The experimental results showed that the strong visible emission around 649 nm from Tm3+(1G4 --> 3F4) and near-infrared (NIR) emission around 1003 nm from Yb3+(2F5/2 --> 2F7/2) of LuPO4:Tm3+,Yb3+ phosphors were observed under 468 nm excitation, respectively. The Yb3+ concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches 30 mol%. The DC mechanism is also discussed in detail.

  13. Upconversion emission properties of CeO2: Tm3+, Yb3+ inverse opal photonic crystals

    NASA Astrophysics Data System (ADS)

    Cheng, Gong; Wu, Hangjun; Yang, Zhengwen; Liao, Jiayan; Lai, Shenfeng; Qiu, Jianbei; Song, Zhiguo

    2014-10-01

    The ordered and disordered templates were assembled by vertical deposition of polystyrene microspheres. The CeO2: Tm3+, Yb3+ precursor solution was used to infiltrate into the voids of the ordered and disordered templates, respectively. Then the ordered and disordered templates were calcined at 950°C in an air furnace, and the CeO2: Tm3+, Yb3+ inverse opals were obtained. The upconversion emissions from CeO2: Tm3+, Yb3+ inverse opals were suppressed due to the photon trapping caused by Bragg reflection of lattice planes when the upconversion emission band was in the range of the photonic band gaps in the inverse opals.

  14. Optical properties and laser performance of some Yb 3+, Er 3+ and Tm 3+-doped silicates

    NASA Astrophysics Data System (ADS)

    Souriau, J. C.; Romero, R.; Borel, C.; Wyon, Ch.; Li, C.; Moncorgé, R.

    1994-12-01

    This paper reports the main spectroscopic characterizations and laser experiments carried out on two new crystal hosts: the yttrium orthosilicate Y 2SiO 5 and the silicate oxyapatite SrY 4(SiO 4) 3O (hereafter noted SYS), doped with ytterbium and erbium for a 1.55 μm laser emission and with thulium for a 2 μm emission. Four new lasers have been demonstrated at 1.554 μm, 1.576 μm, 1.99 μm and 2.05 μm for respectively Yb, Er:SYS; Yb,Er:Y 2SiO 5; Tm:SYS and Tm:Y 2SiO 5. If for Yb,Er-codoped materials laser performances are still poor compared with the Yb,Er phosphate glass, the Tm-doped materials exhibit laser performances similar to the Tm: YAG and look very promising.

  15. Buffer-gas loaded MOTs for Ho, Yb,Tm, and Er

    NASA Astrophysics Data System (ADS)

    Chae, Eunmi; Drayna, Garrett; Hemmerling, Boerge; Hutzler, Nick; Ravi, Aakash; Collopy, Alejandra; Hummon, Matthew; Stuhl, Benjamin; Yeo, Mark; Ye, Jun; Doyle, John

    2014-05-01

    We report on direct loading of lanthanide atoms into MOTs from a two-stage slow buffer-gas beam source, which has a peak forward velocity of ~ 30 - 60 m/s, considerably lower than other beam implementations. The low velocity combined with species generality makes this source useful for loading magneto-optical traps (MOTs), especially for species that are not well suited to the traditional approach of oven plus Zeeman slower. We report loading MOTs with Yb, Tm, Er, and Ho, without any additional slowing stages. Application of a single frequency slowing laser to the buffer-gas beam of Yb results in an unprecedentedly high loading rate of 2 . 0 (1 . 0) ×1010 Yb atoms/s and 1 . 3 (0 . 7) ×108 Yb atoms in the MOT. We plan to use this versatile source to load a MOT with CaF, following the same general approach to that used with YO and SrF.

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

    NASA Astrophysics Data System (ADS)

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

    2016-05-01

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

  17. Upconversion emission in antimony-germanate double-clad optical fiber co-doped with Yb3+/Tm3+ ions

    NASA Astrophysics Data System (ADS)

    Kochanowicz, M.; Dorosz, D.; Zmojda, J.; Miluski, P.; Dorosz, J.; Pisarska, J.; Pisarski, W. A.

    2015-03-01

    In the paper upconversion luminescence properties in Yb3+/Tm3+ co-doped antimony-germanate glass and double-clad optical fiber were studied. The concentration of lanthanides, which has shown the highest upconversion emission intensity at 478 nm (1G4 → 3H6) and 650 nm (1G4 → 3F4), is 1Yb2O3/0.1Tm2O3 (mol%) as a result of exciting with a laser diode (976 nm). The lifetime of 2F5/2 (Yb3+) level decreases from 781 μs to 71 μs in the presence of Tm3+ 0.1-0.75 mol% respectively. Luminescence decay curve of glass co-doped with 1Yb2O3/0.75Tm2O3 suggests donor-donor fast migration followed by Tm3+ → Yb3+ energy transfer. Glass characterized by highest intensity of upconversion luminescence (1Yb2O3/0.1Tm2O3 mol%) was used as core of double-clad optical fiber made by modified rod-in-tube method. Mechanisms influencing differences in upconversion amplified spontaneous emission of the fabricated optical fiber and bulk glass were discussed. Reabsorption of the amplified spontaneous emission signal along the fibre resulting from Tm3+:3H6 → 1G4, transition was observed.

  18. Nanopatterned PMMA-Yb:Er/Tm:Lu2O3 composites with visible upconversion emissions.

    PubMed

    Han, X; Maiz, J; Mijangos, C; Zaldo, C

    2014-05-23

    Nanopillars, nanotubes and nanofibers of transparent polymethyl methacrylate (PMMA) polymer with Yb:Ln:Lu2O3 (Ln = Er or Tm) nanoparticles (NPs) (≈30-35 nm average size) have been prepared by infiltration of anodized aluminum oxide hexagonally nanopatterned templates. The outer diameter of these nanostructures is in the 330-400 nm range, with lengths up to 50 μm and a period distance of 430 nm. These nanostructures show visible upconversion (UC) emissions under excitation with 978 nm light. The steady state temperature of the polymer nanostructures is optically evidenced by the Er(3+) UC emission and optically controlled around the PMMA glass transition temperature by the excitation light, introducing a new method for NP storage in a solid and potential optically induced particle release. Full color emission is shown in tridoped (Yb:Er:Tm) samples. PMID:24784527

  19. Nanopatterned PMMA-Yb:Er/Tm:Lu2O3 composites with visible upconversion emissions

    NASA Astrophysics Data System (ADS)

    Han, X.; Maiz, J.; Mijangos, C.; Zaldo, C.

    2014-05-01

    Nanopillars, nanotubes and nanofibers of transparent polymethyl methacrylate (PMMA) polymer with Yb:Ln:Lu2O3 (Ln = Er or Tm) nanoparticles (NPs) (≈30-35 nm average size) have been prepared by infiltration of anodized aluminum oxide hexagonally nanopatterned templates. The outer diameter of these nanostructures is in the 330-400 nm range, with lengths up to 50 μm and a period distance of 430 nm. These nanostructures show visible upconversion (UC) emissions under excitation with 978 nm light. The steady state temperature of the polymer nanostructures is optically evidenced by the Er3+ UC emission and optically controlled around the PMMA glass transition temperature by the excitation light, introducing a new method for NP storage in a solid and potential optically induced particle release. Full color emission is shown in tridoped (Yb:Er:Tm) samples.

  20. Color Tunable and Upconversion Luminescence in Yb-Tm Co-Doped Yttrium Phosphate Inverse Opal Photonic Crystals.

    PubMed

    Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

    2016-04-01

    For this paper, YPO4: Tm, Yb inverse opals with the photonic band gaps at 475 nm and 655 nm were prepared by polystyrene colloidal crystal templates. We investigated the influence of photonic band gaps on the Tm-Yb upconversion emission which was in the YPO4: Tm Yb inverse opal photonic crystals. Comparing with the reference sample, significant suppression of both the blue and red upconversion luminescence of Tm3+ ions were observed in the inverse opals. The color purity of the blue emission was improved in the inverse opal by the suppression of red upconversion emission. Additionally, mechanism of upconversion emission in the inverse opal was discussed. We believe that the present work will be valuable for not only the foundational study of upconversion emission modification but also the development of new optical devices in upconversion lighting and display. PMID:27451700

  1. Color Tunable and Upconversion Luminescence in Yb-Tm Co-Doped Yttrium Phosphate Inverse Opal Photonic Crystals.

    PubMed

    Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

    2016-04-01

    For this paper, YPO4: Tm, Yb inverse opals with the photonic band gaps at 475 nm and 655 nm were prepared by polystyrene colloidal crystal templates. We investigated the influence of photonic band gaps on the Tm-Yb upconversion emission which was in the YPO4: Tm Yb inverse opal photonic crystals. Comparing with the reference sample, significant suppression of both the blue and red upconversion luminescence of Tm3+ ions were observed in the inverse opals. The color purity of the blue emission was improved in the inverse opal by the suppression of red upconversion emission. Additionally, mechanism of upconversion emission in the inverse opal was discussed. We believe that the present work will be valuable for not only the foundational study of upconversion emission modification but also the development of new optical devices in upconversion lighting and display.

  2. Synthesis, persistent luminescence, and thermoluminescence properties of yellow Sr3SiO5:Eu2+,RE3+ (RE=Ce, Nd, Dy, Ho, Er, Tm, Yb) and orange-red Sr(3-x)Ba(x)SiO5:Eu2+, Dy3+ phosphor.

    PubMed

    Li, Ye; Li, Baohong; Ni, Chenchen; Yuan, Shuxia; Wang, Jing; Tang, Qiang; Su, Qiang

    2014-02-01

    Sunlight-excitable orange or red persistent oxide phosphors with excellent performance are still in great need. Herein, an intense orange-red Sr3-xBaxSiO5:Eu(2+),Dy(3+) persistent luminescence phosphor was successfully developed by a two-step design strategy. The XRD patterns, photoluminescence excitation and emission spectra, and the thermoluminescence spectra were investigated in detail. By adding non-equivalent trivalent rare earth co-dopants to introduce foreign trapping centers, the persistent luminescence performance of Eu(2+) in Sr3SiO5 was significantly modified. The yellow persistent emission intensity of Eu(2+) was greatly enhanced by a factor of 4.5 in Sr3SiO5:Eu(2+),Nd(3+) compared with the previously reported Sr3SiO5:Eu(2+), Dy(3+). Furthermore, Sr ions were replaced with equivalent Ba to give Sr3-xBaxSiO5 :Eu(2+),Dy(3+) phosphor, which shows yellow-to-orange-red tunable persistent emissions from λ=570 to 591 nm as x is increased from 0 to 0.6. Additionally, the persistent emission intensity of Eu(2+) is significantly improved by a factor of 2.7 in Sr3-xBaxSiO5 :Eu(2+),Dy(3+) (x=0.2) compared with Sr3SiO5 :Eu(2+),Dy(3+). A possible mechanism for enhanced and tunable persistent luminescence behavior of Eu(2+) in Sr3-xBaxSiO5:Eu(2+),RE(3+) (RE=rare earth) is also proposed and discussed.

  3. Broadband telecommunication wavelength emission in Yb(3+)-Er(3+)-Tm(3+) co-doped nano-glassceramics.

    PubMed

    Tikhomirov, V K; Driesen, K; Görller-Walrand, C; Mortier, M

    2007-07-23

    Transparent Yb(3+), Er(3+) and Tm(3+) co-doped nano-glass-ceramics 3(SiO(2)2)9(AlO(1.5))31.5(CdF(2))18.5(PbF(2))5.5(ZnF(2)):3.5(Yb-Er-TmF(3)), mol%, have been prepared where co-dopants mostly partition in nano-crystals Pb(1-x) (Yb(3+),Er(3+),Tm(3+))(x)F(2+x) embedded in the glass network. The Yb(3+) ensures high absorption at 980 nm telecommunication pump wavelength and further phonon-mediated energy transfer to Er(3+) and Tm(3+) co-dopants. Er(3+) and Tm(3+) radiate overlapping emission bands from their lowest energy levels, with similar lifetime of about 9 ms, which cover the range between 1.50 to 1.70 mum. The lifetime of all higher levels of Er(3+) and Tm(3+) dopants is shorter than 70 mus due to short inter-dopant distances in the nano-crystals resulting in fast energy transfer to their lowest levels.

  4. Trapping processes in CaS:Eu{sup 2+},Tm{sup 3+}

    SciTech Connect

    Jia, Dongdong; Jia, Weiyi; Evans, D. R.; Dennis, W. M.; Liu, Huimin; Zhu, Jing; Yen, W. M.

    2000-09-15

    CaS:Eu{sup 2+},Tm{sup 3+} is a persistent red phosphor. Thermoluminescence was measured under different excitation and thermal treatment conditions. The results reveal that the charge defects, created by substituting Tm{sup 3+} for Ca{sup 2+}, serve as hole traps for the afterglow at room temperature. Tm{sup 3+} plays the role of deep electron trapping centers, capturing electrons either through the conduction band or directly from the excited Eu{sup 2+} ions. These two processes, in which two different sites of Tm{sup 3+} are involved, correspond to two traps with different depths. (c) 2000 American Institute of Physics.

  5. Intense ultraviolet upconversion emission from water-dispersed colloidal YF3:Yb3+/Tm3+ rhombic nanodisks.

    PubMed

    Qiu, Hailong; Chen, Guanying; Fan, Rongwei; Yang, Liming; Liu, Cheng; Hao, Shuwei; Sailor, Michael J; Ågren, Hans; Yang, Chunhui; Prasad, Paras N

    2014-01-21

    Intense ultraviolet upconversion emission has been observed in water-dispersed uniform rhombic nanodisks (side length of ~14 nm and thickness of ~2.5 nm) of YF3 co-doped with Yb(3+) sensitizer and Tm(3+) activator ions, when excited at ~980 nm.

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

    PubMed

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

    2016-04-01

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

  7. Quantum sized Ag nanocluster assisted fluorescence enhancement in Tm3+-Yb3+ doped optical fiber beyond plasmonics

    NASA Astrophysics Data System (ADS)

    Chattopadhyay, Rik; Haldar, Arindam; Paul, Mukul C.; Das, Shyamal; Bhadra, Shyamal K.

    2015-12-01

    We report a process for enhancing fluorescence emission from conventional rare earth ions in optical fiber by metal nanocluster (MNC) in nonresonant indirect pumping. The process is completely different from formal metal enhanced fluorescence phenomenon as the MNCs are too small in size to support localized surface plasmon and the excitation wavelength is far from plasmon resonance frequency. We used an established theory of two coupled oscillators to explain the simultaneous enhancement of Ytterbium (Yb3+) and Thulium (Tm3+) emission by silver (Ag) NCs under nonresonant pumping in optical fiber. The fiber is pumped with a 980 nm fiber pigtailed laser diode with input power of 20-100 mW to excite the Yb3+. Four times enhancement of Yb3+ emission of 900-1100 nm and Tm3+ upconversion emission around 474 nm, 650 nm, and 790 nm is observed in the fiber with Ag NCs.

  8. Broad-beam transmission data for new brachytherapy sources, Tm-170 and Yb-169.

    PubMed

    Granero, Domingo; Pérez-Calatayud, José; Ballester, Facundo; Bos, Adrie J J; Venselaar, Jack

    2006-01-01

    The characteristics of the radionuclides (170)Tm and (169)Yb are highly interesting for their use as high dose-rate brachytherapy sources. The introduction of brachytherapy equipment containing these sources will lead to smaller required thicknesses of the materials used in radiation protection barriers compared with the use of conventional sources such as (192)Ir and (137)Cs. The purpose of this study is to determine the required thicknesses of protection material for the design of the protecting walls. Using the Monte Carlo method, transmission data were derived for broad-beam geometries through lead and concrete barriers, from which the first half value layer and tenth value layer are obtained. In addition, the dose reduction in a simulated patient was studied to determine whether transmission in the patient is a relevant factor in radiation protection calculations. PMID:16030058

  9. Green up-conversion in Yb 3+-Tb 3+ and Yb 3+-Tm 3+-Tb 3+ doped fluoro-germanate bulk glass and fibre

    NASA Astrophysics Data System (ADS)

    Scarnera, V.; Richards, B.; Jha, A.; Jose, G.; Stacey, C.

    2010-12-01

    Yb 3+-Tb 3+ and Yb 3+-Tm 3+-Tb 3+ doped fluoro-germanate glass samples were fabricated in bulk and fibre form. Bright up-conversion has been obtained by exciting the samples with a 975 nm laser source, and the power dependence of the up-conversion intensities with respect to the excitation power has been characterised. Two mechanisms must be taken into account to explain the population of the 5D 4 level of the terbium ions in these experiments; namely multi excited state absorption (MESA) and cooperative up-conversion (CU). While in the Yb 3+-Tm 3+-Tb 3+ samples both MESA and CU contribute simultaneously to the 5D 4:Tb 3+ population, in the Yb 3+-Tb 3+ case a pure CU mechanism is responsible for the 5D 4:Tb 3+ population. In the fibre geometry, the re-absorption effect has been observed. The detrimental role of the re-absorption has been explained by characterising the up-conversion spectrum at different fibre lengths.

  10. Selective biosorption of lanthanide (La, Eu, Yb) ions by Pseudomonas aeruginosa

    SciTech Connect

    Texier, A.C.; Andres, Y.; Cloirec, P. le

    1999-02-01

    The ability of Pseudomonas aeruginosa to adsorb selectively La{sup 3+}, Eu{sup 3+}, and Yb{sup 3+} from aqueous solution was investigated. The lanthanide biosorption equilibrium obeyed the Brunauer-Emmett-Teller isotherm model, indicating multilayer adsorption. Determined levels of maximum adsorption capacities were 397 {micro}mol/g for lanthanum, 290 {micro}mol/g for europium and 326 {micro}mol/g for ytterbium. The results indicated that there were about 100 preferential sites for lanthanum per g of dry biomass. Experiments with mixed-cation solutions showed that the sequence of preferential biosorption was Eu{sup 3+} = Yb{sup 3+} > La{sup 3+}. Biomass dried at 37 and 70 C showed the same selective behavior as wet biomass. Inert microbial biomass dried at 37 C appeared to be the most efficient form for experimental use. The uptake of lanthanide by P. aeruginosa cells was not affected by the presence of sodium, potassium, calcium, chloride, sulfate and nitrate ions. Aluminum was a strong inhibitor of lanthanide ions biosorption. 87% of the total Al{sup 3+} was removed from the 3 mM solution, whereas only 8%, 20% and 3% of the total La{sup 3+}, Eu{sup 3+}, and Yb{sup 3+}, respectively, were sorbed from 3 mM solutions. The results suggested that cells of Pseudomonas aeruginosa may find promising applications for removal and separation of lanthanide ions from aqueous effluents.

  11. Near infrared quantum cutting of Na+ and Eu2+-Yb3+ couple activated SrF2 crystal

    NASA Astrophysics Data System (ADS)

    Yagoub, M. Y. A.; Swart, H. C.; Dhlamini, M. S.; Coetsee, E.

    2016-10-01

    Na+ and Eu2+-Yb3+ couple activated SrF2 phosphor powders were synthesized by the co-precipitation method. The structure and luminescence properties of the system were investigated. X-ray diffraction data indicated that a mixture of cubic SrF2 and NaYbF4 phases gradually formed with an increase in the Yb3+ ion doping concentration. Diffuse reflectance has been used to confirm the existence of europium in the divalent state. The possibility of quantum cutting in the Eu2+-Yb3+ ions co-doped SrF2 crystal was discussed. Energy transfer that occurred subsequently from Eu2+ to Yb3+ was followed by an intense near-infrared (NIR) (∼1000 nm) emission spectral range. Emission spectra and the fluorescence decay measurements have been utilized to demonstrate the cooperative energy transfer in the Eu2+-Yb3+ couple ions. The energy transfer was completed at high concentration and the Yb3+ ions emission's intensity was reduced as a result of concentration quenching. In addition from the photoluminescence data it was also evident that Na+ induced a significant change to the NIR emission.

  12. Energy transfer and visible-infrared quantum cutting photoluminescence modification in Tm-Yb codoped YPO(4) inverse opal photonic crystals.

    PubMed

    Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

    2015-08-01

    YPO4:  Tm, Yb inverse opal photonic crystals were successfully synthesized by the colloidal crystal templates method, and the visible-infrared quantum cutting (QC) photoluminescence properties of YPO4:  Tm, Yb inverse opal photonic crystals were investigated. We obtained tetragonal phase YPO4 in all the samples when the samples sintered at 950°C for 5 h. The visible emission intensity of Tm3+ decreased significantly when the photonic bandgap was located at 650 nm under 480 nm excitation. On the contrary, the QC emission intensity of Yb3+ was enhanced as compared with the no photonic bandgap sample. When the photonic bandgap was located at 480 nm, the Yb3+ and Tm3+ light-emitting intensity weakened at the same time. We demonstrated that the energy transfer between Tm3+ and Yb3+ is enhanced by the suppression of the red emission of Tm3+. Additionally, the mechanisms for the influence of the photonic bandgap on the energy transfer process of the Tm3+, Yb3+ codoped YPO4 inverse opal are discussed. PMID:26368098

  13. Energy transfer and visible-infrared quantum cutting photoluminescence modification in Tm-Yb codoped YPO(4) inverse opal photonic crystals.

    PubMed

    Wang, Siqin; Qiu, Jianbei; Wang, Qi; Zhou, Dacheng; Yang, Zhengwen

    2015-08-01

    YPO4:  Tm, Yb inverse opal photonic crystals were successfully synthesized by the colloidal crystal templates method, and the visible-infrared quantum cutting (QC) photoluminescence properties of YPO4:  Tm, Yb inverse opal photonic crystals were investigated. We obtained tetragonal phase YPO4 in all the samples when the samples sintered at 950°C for 5 h. The visible emission intensity of Tm3+ decreased significantly when the photonic bandgap was located at 650 nm under 480 nm excitation. On the contrary, the QC emission intensity of Yb3+ was enhanced as compared with the no photonic bandgap sample. When the photonic bandgap was located at 480 nm, the Yb3+ and Tm3+ light-emitting intensity weakened at the same time. We demonstrated that the energy transfer between Tm3+ and Yb3+ is enhanced by the suppression of the red emission of Tm3+. Additionally, the mechanisms for the influence of the photonic bandgap on the energy transfer process of the Tm3+, Yb3+ codoped YPO4 inverse opal are discussed.

  14. Thermal decomposition assisted synthesis and upconversion property of Fe3O4@YPO4:Tm/Yb hybrid nano-composite phosphor

    NASA Astrophysics Data System (ADS)

    Tiwari, S. P.; Kumar, K.; Rai, V. K.

    2015-06-01

    Hybrid nano-composite phosphor has been successfully synthesized through thermal decomposition method. The dual phase of samples assigned by XRD analysis shows the formation of nano-composite with crystallite size 20 nm and 12 nm for YPO4: Tm/Yb and Fe3O4@YPO4:Tm/Yb respectively. The FESEM images show the spherical shape and non agglomerated formation of nanoparticles. Three bands in upconversion emission mode were found in intense blue at 472 nm, red at 662 nm and NIR at 798 nm regions corresponding to1G4 → 3H6, 1G4 → 3F4 and 3H4 → 3H6 transition states respectively. The lifetime for1G4 → 3H6 level is found 1150 microsecond and 1400 microsecond for YPO4: Tm/Yb and Fe3O4@YPO4:Tm/Yb samples respectively.

  15. Mechanochemical preparation of nanocrystalline NaYF4:Gd3+/Yb3+/Tm3+: An efficient upconversion phosphor

    NASA Astrophysics Data System (ADS)

    Zhang, Jun; Riesen, Hans

    2015-11-01

    We report on a mechanochemical preparation route for NaYF4:Gd3+/Yb3+/Tm3+ nanoparticles by ball-milling NaF, YF3, GdF3, YbF3 and TmF3 at room temperature. An analysis by XRD and TEM demonstrates that the resulting materials are mainly (∼88% after 4 h ball-milling) in the hexagonal phase and are on the nanoscale with an average crystallite size of ∼20 nm. The prepared nanoparticles display efficient upconversion emission; upon excitation by a 980 nm laser diode, bright visible blue light emission can be observed. However, in accord with previous results, the strongest emission is observed in the NIR at 800 nm.

  16. Visible to near-infrared downconversion in Tm3+/Yb3+ co-doped chalcohalide glasses for solar spectra converter

    NASA Astrophysics Data System (ADS)

    Huang, Fei; Chen, Liyan; Han, Ying; Tang, Junzhou; Nie, Qiuhua; Zhang, Peiqing; Xu, Yinsheng

    2015-07-01

    Near-infrared downconversion which can be used to improve the utilization of solar spectral has drawn much attention. In this work, chalcohalide glasses with compositions of 50GeS2-25Ga2S3-25CsCl (in mol.%): 0.1 wt.% Tm2 S3 - x wt.% Yb2S3 (x = 0, 0.1, 0.2, 0.3) were synthesized by vacuumed melt-quenching method. Absorption spectra, emission spectra, excitation spectra, and decay measurements were performed to prove the occurrence of cooperative energy transfer from the 1G4 level of Tm3+ ions to two Yb3+ ions. Quantum efficiency depends on Yb3+ concentration is calculated, and the highest is 114.1%. The photon energy of Yb3+ emission around 1 μm well matched with the operation band gap of the crystalline Si, so the glasses could potentially be applied in Si-based solar cell.

  17. Formation enthalpies of LaLn'O3 (Ln'=Ho, Er, Tm and Yb) interlanthanide perovskites

    NASA Astrophysics Data System (ADS)

    Qi, Jianqi; Guo, Xiaofeng; Mielewczyk-Gryn, Aleksandra; Navrotsky, Alexandra

    2015-07-01

    High-temperature oxide melt solution calorimetry using 3Na2O·MoO3 at 802 °C was performed for interlanthanide perovskites LaLn'O3 (Ln'=Ho, Er, Tm and Yb) and lanthanide oxides (La2O3, Ho2O3, Er2O3, Tm2O3 and Yb2O3). The enthalpies of formation of these interlanthanide perovskites from binary lanthanide oxides at room temperature (25 °C) were determined to be -8.3±3.4 kJ/mol for LaHoO3, -9.9±3.0 kJ/mol for LaErO3, -10.8±2.7 kJ/mol for LaTmO3 and -12.3±2.9 kJ/mol for LaYbO3. There is a roughly linear relationships between these enthalpy values and the tolerance factor for these and for other LaM3+O3 (M=In, Sc, Ga, Al, Fe and Cr) perovskites, confirming that the distortion of the perovskites as results from ionic radius difference of A-site and B-site cations, is the main factor determining the stability of these compounds.

  18. Color tunability with temperature and pump intensity in Yb3+/Tm3+ codoped aluminosilicate glass under anti-Stokes excitation.

    PubMed

    Silva, W F; Eliel, G S N; dos Santos, P V; de Araujo, M T; Vermelho, M V D; Udo, P T; Astrath, N G C; Baesso, M L; Jacinto, C

    2010-07-21

    Pump and thermally induced color tunabilities were demonstrated in Yb(3+)/Tm(3+) codoped low silica calcium aluminosilicate (LSCAS) glass under anti-Stokes excitation at 1.064 microm. The effects of pump intensity and sample's temperature on the upconversion emissions and mainly on the color tunabilities (from 800 to 480 nm) were investigated. The results revealed a 20- and a threefold reductions at 800/480 nm ratio as, respectively, the pump intensity and sample's temperature were increased from 27 to 700 kW/cm(2) and from 296 to 577 K. These behaviors with pump intensity and temperature (a strong increase of the 480 nm emission in comparison with the 800 nm one) were attributed to the several efficient processes occurring in the LSCAS system (Yb(3+)-->Tm(3+) energy-transfer processes, easy saturations of the Yb(3+) and Tm(3+) excited states, and radiative emissions). Besides these assigns, the temperature dependence is mainly assigned to the temperature-dependent effective absorption cross section of the ytterbium sensitizer through the so-called multiphonon-assisted anti-Stokes excitation process. Theoretical analyses and fits of the experimental data provided quantitative information. PMID:20649337

  19. Color tunability with temperature and pump intensity in Yb3+/Tm3+ codoped aluminosilicate glass under anti-Stokes excitation.

    PubMed

    Silva, W F; Eliel, G S N; dos Santos, P V; de Araujo, M T; Vermelho, M V D; Udo, P T; Astrath, N G C; Baesso, M L; Jacinto, C

    2010-07-21

    Pump and thermally induced color tunabilities were demonstrated in Yb(3+)/Tm(3+) codoped low silica calcium aluminosilicate (LSCAS) glass under anti-Stokes excitation at 1.064 microm. The effects of pump intensity and sample's temperature on the upconversion emissions and mainly on the color tunabilities (from 800 to 480 nm) were investigated. The results revealed a 20- and a threefold reductions at 800/480 nm ratio as, respectively, the pump intensity and sample's temperature were increased from 27 to 700 kW/cm(2) and from 296 to 577 K. These behaviors with pump intensity and temperature (a strong increase of the 480 nm emission in comparison with the 800 nm one) were attributed to the several efficient processes occurring in the LSCAS system (Yb(3+)-->Tm(3+) energy-transfer processes, easy saturations of the Yb(3+) and Tm(3+) excited states, and radiative emissions). Besides these assigns, the temperature dependence is mainly assigned to the temperature-dependent effective absorption cross section of the ytterbium sensitizer through the so-called multiphonon-assisted anti-Stokes excitation process. Theoretical analyses and fits of the experimental data provided quantitative information.

  20. Properties of single crystalline AZn2Sb2 (A=Ca,Eu,Yb)

    SciTech Connect

    May, Andrew F; McGuire, Michael A; Ma, Jie; Delaire, Olivier A; Huq, Ashfia; Custelcean, Radu

    2012-01-01

    Single crystals of CaZn{sub 2}Sb{sub 2}, EuZn{sub 2}Sb{sub 2}, and YbZn{sub 2}Sb{sub 2} were grown from melts of nominal composition AZn{sub 5}Sb{sub 5} (A = Ca,Eu,Yb) with the excess melt being removed at 1073 K. The electrical transport properties are consistent with those previously reported for polycrystalline samples. This confirms that the p-type carrier concentrations ranging from 2 x 10{sup 19} cm{sup -3} to -1 x 10{sup 20} cm{sup -3} are intrinsic to these materials. Also consistent with transport in polycrystalline materials, the carrier mobility is found to be lowest in CaZn{sub 2}Sb{sub 2}, suggesting the trends in mobility and thermoelectric efficiency within these compounds are inherent to the material systems and not due to inhomogeneity or impurities in polycrystalline samples. These results suggest CaZn{sub 2}Sb{sub 2} has the strongest coupling between the doping/defects and the electronic framework. Magnetization measurements reveal an antiferromagnetic transition near 13 K in EuZn{sub 2}Sb{sub 2}, and the observed magnetic anisotropy indicates the spins align parallel and anti-parallel to c in the trigonal lattice. Powder neutron diffraction on polycrystalline samples of CaZn{sub 2}Sb{sub 2} and YbZn{sub 2}Sb{sub 2} reveals smooth lattice expansion to 1000 K, with c expanding faster than a. The Debye temperatures calculated from specific heat capacity data and the isotropic displacement parameters are found to correlate with the carrier mobility, with the CaZn{sub 2}Sb{sub 2} displaying the largest Debye temperature and smallest mobility.

  1. White light upconversion emissions in Er3+/Tm3+/Yb3+ tridoped oxyfluoride glass

    NASA Astrophysics Data System (ADS)

    Guan, Xiaoping; Xu, Wei; Zhu, Shuang; Song, Qiutong; Wu, Xijun; Liu, Hailong

    2015-10-01

    Rare earth ions doped glasses producing visible upconversion emissions are of great interest due to their potential applications in the photonics filed. In fact, practical application of upconversion emissions has been used to obtain color image displays and white light sources. However, there are few reports on the thermal effect on tuning the emission color of the RE doped materials. In this work, the Er3+/Tm3+/Yb3+ tridoped oxyfluoride glasses were prepared through high temperature solid-state method. Under a 980 nm diode laser excitation, the upconversion emissions from the samples were studied. At room-temperature, bright white luminescence, whose CIE chromaticity coordinate was about (0.28, 0.31), can be obtained when the excitation power was 120 mW. The emission color was changed by varying the intensity ratios between RGB bands, which are strongly dependent on the rare earth ions concentration. The temperature dependent color emissions were also investigated. As temperature increased, the intensities for the emission bands presented different decay rates, finally resulting in the changing of the CIE coordinate. When the temperature was 573 K, white light with color coordinate of (0.31, 0.33) was achieved, which matches well with the white reference (0.33, 0.33). The color tunability, high quality of white light and intense emission intensity make the transparent oxyfluoride glasses excellent candidates for applications in solid-state lighting.

  2. Composition tuning the upconversion emission in NaYF4:Yb/Tm hexaplate nanocrystals.

    PubMed

    Zhang, Hua; Li, Yujing; Lin, Yungchen; Huang, Yu; Duan, Xiangfeng

    2011-03-01

    Single crystal hexagonal NaYF4:Yb/Tm nanocrystals have been synthesized with uniform size, morphology and controlled chemical composition. Spectroscopic studies show that these nanocrystals exhibit strong energy upconversion emission when excited with a 980 nm diode laser, with two primary emission peaks centered around 452 nm and 476 nm. Importantly, the overall and relative emission intensity at these wavelengths can be readily tuned by controlling the concentration of the trivalent rare earth element dopants at the beginning of the synthesis which has been confirmed by EDX for the first time. Through systematic studies, the optimum rare earth ion doping concentration can be determined for the strongest emission intensity at the selected peak(s). Confocal microscopy studies show that the upconversion emission from individual NCs can be readily visualized. These studies demonstrate a rational approach for fine tuning the upconversion properties in rare-earth doped nanostructures and can broadly impact areas ranging from energy harvesting, energy conversion to biomedical imaging and therapeutics. PMID:21264435

  3. Solvent extraction behavior of trivalent Nd, Eu, Ho, and Yb with dibenzoylmethane at 80{degree}C

    SciTech Connect

    Gao, J.; Choppin, G.R.

    1995-05-01

    The extraction behavior of trivalent lanthanide ions (Nd, Eu, Ho and Yb) has been studied with dibenzoylmethane (DBM) at 80{degree}C using molten paraffin wax as diluent. In the range of pH 7 to 8, the extraction of lanthanide cations is greater than 90%. The ratio of Ln:DBM in the extracted species was determined to be 1:3 by the slope analysis method. The pH{sub 1/2} values of extraction and the extraction constants of Nd(III), Eu(III), Ho(III) and Yb(III) are reported. 22 refs., 2 figs., 1 tab.

  4. MOLTEN SALT SYNTHESIS OF YF3:Yb3+/Ln3+(Ln = Er3+, Tm3+) MICROSHEETS WITH MULTICOLOR UPCONVERSION LUMINESCENCE

    NASA Astrophysics Data System (ADS)

    Ding, Mingye; Lu, Chunhua; Cao, Linhai; Ni, Yaru; Xu, Zhongzi

    2013-12-01

    In this paper, highly crystalline YF3:Yb3+/Ln3+(Ln = Er3+, Tm3+) microsheets were successfully synthesized by a surfactant-free molten salt method for the first time. The results indicated that the as-obtained samples belonged to orthorhombic system and exhibited microsheets morphology with side lengths of 30 to 80 μm and wall thickness from 1 to 1.5 μm. By changing the dopant's species (Ln3+), multicolor (yellow and blue) upconversion emission can be observed in YF3:Yb3+/Ln3+ microsheets under 980 nm laser diode (LD) excitation. The upconversion mechanisms in co-doping YF3 samples were analyzed in detail based on the emission spectra. Importantly, this approach not only proposes a new alternative in synthesizing such materials, but also opens the possibility to meet the increasing commercial demand.

  5. Improved Near-Infrared Up-Conversion Emission of Tm3+ Sensitized by Yb3+ and Ho3+ in LuF3 Nanocrystals.

    PubMed

    Xu, Xuhui; Wu, Yumei; Bian, Wenjuan; Yu, Xue; Zhang, Buhao; Li, Qianyue; Qiu, Jianbei; Liu, BiTao

    2016-04-01

    In the present work, mono-disperse and uniform orthorhombic lutetium fluoride (LuF3) nanocrystals with an average size of about 35 nm have been successfully synthesized by a simple ionothermal method without any template. The infrared (IR) to visible up-conversion (UC) photoluminescence of LuF3 doped with Yb3+, Tm3+, and Ho3+ under 980 nm excitation was systemically studied. The intensity of near infrared (NIR) to visible up-conversion emission of Tm3+ was improved efficiently by adding Yb3+ and Ho3+ in LuF3, especially for the broad NIR emission band located at 812 nm. Meanwhile, compared to the Yb3+ and Tm3+ co-doped LuF3, the ratio of red to green emission in the Yb3+, TmS+, and HoS+ co-doped LuF3 changed greatly, and a bright yellowish-green emission was observed under 980 nm laser excitation. It shows that Yb3+, Tm3+ and Ho3+ co-doped LuF3 nanocrystals provided a potential application in vitro and in vivo bio-imaging, color displays and optical storage. PMID:27451685

  6. Highly improved upconversion luminescence in NaGd(WO4)2:Yb3+/Tm3+ inverse opal photonic crystals

    NASA Astrophysics Data System (ADS)

    Wang, Yunfeng; Xu, Wen; Cui, Shaobo; Xu, Sai; Yin, Ze; Song, Hongwei; Zhou, Pingwei; Liu, Xiaoyan; Xu, Lin; Cui, Haining

    2015-01-01

    The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb3+/Tm3+ inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm3+ ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL 1D2-3H6/3F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm3+ was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm3+ was largely improved due to the periodic macroporous structure.The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb3+/Tm3+ inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm3+ ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL 1D2-3H6/3F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was

  7. Formation enthalpies of LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) interlanthanide perovskites

    SciTech Connect

    Qi, Jianqi; Guo, Xiaofeng; Mielewczyk-Gryn, Aleksandra

    2015-07-15

    High-temperature oxide melt solution calorimetry using 3Na{sub 2}O·MoO{sub 3} at 802 °C was performed for interlanthanide perovskites LaLn'O{sub 3} (Ln'=Ho, Er, Tm and Yb) and lanthanide oxides (La{sub 2}O{sub 3}, Ho{sub 2}O{sub 3}, Er{sub 2}O{sub 3}, Tm{sub 2}O{sub 3} and Yb{sub 2}O{sub 3}). The enthalpies of formation of these interlanthanide perovskites from binary lanthanide oxides at room temperature (25 °C) were determined to be −8.3±3.4 kJ/mol for LaHoO{sub 3}, −9.9±3.0 kJ/mol for LaErO{sub 3}, −10.8±2.7 kJ/mol for LaTmO{sub 3} and −12.3±2.9 kJ/mol for LaYbO{sub 3}. There is a roughly linear relationships between these enthalpy values and the tolerance factor for these and for other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites, confirming that the distortion of the perovskites as results from ionic radius difference of A-site and B-site cations, is the main factor determining the stability of these compounds. - Graphical abstract: A linear relationship between the enthalpy of formation and the tolerance factor for interlanthanide LaLn'O{sub 3} (Ln'=Ho, Er, Tm, and Yb) and other LaM{sup 3+}O{sub 3} (M=In, Sc, Ga, Al, Fe and Cr) perovskites. - Highlights: • Interlanthanide perovskites were synthesized by solid state reactions. • Their enthalpies of formation were measured by oxide melt solution calorimetry. • ΔH{sub f,ox} shows a linear relationship with tolerance factor.

  8. Magnetic and transport properties of some Ln-Ba-Cu-O (Ln=Yb, Tm, Sm) superconducting oxides

    NASA Astrophysics Data System (ADS)

    Marcus, J.; Escribe-Filippini, C.; Schlenker, C.; Buder, R.; Devenyi, J.; Reydet, P. L.

    1987-07-01

    Powders of Yb-Ba-Cu-O, Tm-Ba-Cu-O and Sm-Ba-Cu-O have been synthetized. Electrical resistivity and magnetic susceptibility measurements show that they are superconducting with onset transition temperatures in the range 91 K - 85 K. The thermopower, in these oxides as well as in Sr xLa 2-xCuO 4-δ and Ba 2YCu 3O 7-δ, is found to be positive between T c and 300 K. Hysteresis of the diamagnetic magnetization is also reported.

  9. Energy Transfer and 1.8 µm Emission in Tm³⁺/Yb³⁺ Co-Doped LiYF₄Crystal.

    PubMed

    Yang, Shuo; Xia, Haiping; Zhang, Jiazhong; Jiang, Yongzhang; Gu, Xuemei; Zhang, Jianli; Wang, Dongjie; Jiang, Haochuan; Chen, Baojiu

    2016-01-01

    LiYF₄ single crystals co-doped with various Tm³⁺/Yb³⁺ concentrations were grown using the Bridg- man method. The luminescent properties of the crystals were investigated through emission spectra, emission cross section, and decay curves under excitation by 980 nm. Compared with the Tm³⁺ single-doped LiYF₄ crystal, an enhanced emission band from 1600 to 2150 nm was observed upon excitation of a 980 nm laser diode. The energy transfer from Yb³⁺ to Tm³⁺ and the optimum fluo- rescence emission around 1.80 µm of Tm³⁺ ion were investigated. The maximum emission cross section at 1.8 µm was calculated to be 1.48 x 10⁻²⁰ cm² according to the measured absorption spectrum. The high energy transfer efficiency of 86.5% from Yb³⁺ to Tm³⁺ ion demonstrate that the Yb³⁺ ions can efficiently sensitize the Tm³⁺ ions. PMID:27398484

  10. Pure and almost pure NIR emission of Tm and Tm,Yb-CeO2 under UV, X-ray and NIR up-conversion excitation: key roles of level selective antenna sensitization and charge-compensation.

    PubMed

    Avram, Daniel; Cojocaru, Bogdan; Urda, Adriana; Tiseanu, Ion; Florea, Mihaela; Tiseanu, Carmen

    2015-12-14

    Herein, we report on the pure and almost pure near-infrared (NIR) emission at around 807 nm observed for Tm(Yb) (co)-doped CeO2 nanoparticles (NPs) under UV, X-ray and NIR up-conversion excitation. The optical responses are attributed to the low-lying charge-transfer of CeO2 that acts as a selective antenna sensitizer of the Tm (3)H4 emission and Yb doping that lowers the local symmetry at Tm sites and introduces additional phonon modes. Selective antenna sensitization is also observed for Er/Ho (Yb) (co)-doped CeO2 NPs. To the best of our knowledge, this is a first study which correlates the down- and up-conversion emission properties of lanthanide(s)-(co) dopants with the CeO2 structure highlighting also the outstanding potential of these NPs in high-penetration tissue imaging and therapy.

  11. Pure and almost pure NIR emission of Tm and Tm,Yb-CeO2 under UV, X-ray and NIR up-conversion excitation: key roles of level selective antenna sensitization and charge-compensation.

    PubMed

    Avram, Daniel; Cojocaru, Bogdan; Urda, Adriana; Tiseanu, Ion; Florea, Mihaela; Tiseanu, Carmen

    2015-12-14

    Herein, we report on the pure and almost pure near-infrared (NIR) emission at around 807 nm observed for Tm(Yb) (co)-doped CeO2 nanoparticles (NPs) under UV, X-ray and NIR up-conversion excitation. The optical responses are attributed to the low-lying charge-transfer of CeO2 that acts as a selective antenna sensitizer of the Tm (3)H4 emission and Yb doping that lowers the local symmetry at Tm sites and introduces additional phonon modes. Selective antenna sensitization is also observed for Er/Ho (Yb) (co)-doped CeO2 NPs. To the best of our knowledge, this is a first study which correlates the down- and up-conversion emission properties of lanthanide(s)-(co) dopants with the CeO2 structure highlighting also the outstanding potential of these NPs in high-penetration tissue imaging and therapy. PMID:26411533

  12. 2.7 μm emission properties of Er3+/Yb3+/Eu3+: SrGdGa3O7 and Er3+/Yb3+/Ho3+: SrGdGa3O7 crystals

    NASA Astrophysics Data System (ADS)

    Xia, Houping; Feng, Jianghe; Ji, Yuexia; Sun, Yijian; Wang, Yan; Jia, Zhitai; Tu, Chaoyang

    2016-04-01

    Er3+/Yb3+/Eu3+: SrGdGa3O7 and Er3+/Yb3+/Ho3+: SrGdGa3O7 crystals were grown by Czochralski technology and detailed spectroscopic analyses were carried out. It was found that the spectra of Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal show weaker near-infrared emission and stronger mid-infrared emission as compared with Er3+/Yb3+: SrGdGa3O7 crystal. Furthermore, the lifetime of the 4I13/2 state decreases from 10.58 ms in Er3+/Yb3+: SrGdGa3O7 crystal to 6.87 ms in Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal, that is, the self-saturation for 2.7 μm laser in Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal is suppressed greatly. These results indicate that the doping of Eu3+ in Er3+/Yb3+: SrGdGa3O7 crystal is beneficial to improve the 2.7 μm laser. In contrast, introducing Ho3+ in Er3+/Yb3+: SrGdGa3O7 crystal is adverse to realize Er3+-activated MIR laser operation. So Er3+/Yb3+/Eu3+: SrGdGa3O7 crystal could be a potential MIR gain media for enhanced 2.7 μm laser.

  13. Enhanced NIR downconversion luminescence by precipitating nano Ca5(PO4)3F crystals in Eu2+-Yb3+ co-doped glass.

    PubMed

    Li, Chen; Song, Zhiguo; Li, Yongjin; Lou, Kai; Qiu, Jianbei; Yang, Zhengwen; Yin, Zhaoyi; Wang, Xue; Wang, Qi; Wan, Ronghua

    2013-10-01

    Eu(2+)-Yb(3+) co-doped transparent glass-ceramic containing nano-Ca5(PO4)3F (FAP) was prepared in reducing atmosphere. XRD and TEM analysis indicated that nano-FAP about 40 nm precipitated homogeneously in glass matrix after heat treatment. Confirmed by spectroscopy measurements, the crystal-like absorption and emission of Eu(2+) indicated the partition of Eu(2+) into FAP nanocrystals in glass ceramic. NIR emission due to the transition (2)F5/2→(2)F7/2 of Yb(3+) ions (about 980-1100 nm) was observed from glasses under ultraviolet excitation, ascribed to downconversion from Eu(2+) to Yb(3+), which can be enhanced by precipitating nano-FAP crystals. The results indicated that Eu(2+)-Yb(3+) co-doped glass-ceramic embedding with nano-FAP is a promising candidate as downconversion materials for enhancing conversion efficiency of solar cells.

  14. Tunable multicolor and white-light upconversion luminescence in Yb3+/Tm3+/Ho3+ tri-doped NaYF4 micro-crystals.

    PubMed

    Lin, Hao; Xu, Dekang; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

    2015-09-01

    NaYF4 micro-crystals with various concentrations of Yb(3+) /Tm(3+) /Ho(3+) were prepared successfully via a simple and reproducible hydrothermal route using EDTA as the chelating agent. Their phase structure and surface morphology were studied using powder X-ray diffraction (XRD) and scanning electron microscopy (SEM). The XRD patterns revealed that all the samples were pure hexagonal phase NaYF4. SEM images showed that Yb(3+)/Tm(3+)/Ho(3+) tri-doped NaYF4 were hexagonal micro-prisms. Upconversion photoluminescence spectra of Yb(3+)/Tm(3+)/Ho(3+) tri-doped NaYF4 micro-crystals with various dopant concentrations under 980 nm excitation with a 665 mW pump power were studied. Tunable multicolor (purple, purplish blue, yellowish green, green) and white light were achieved by simply adjusting the Ho(3+) concentration in 20%Yb(3+)/1%Tm(3+)/xHo(3+) tri-doped NaYF4 micro-crystals. Furthermore, white-light emissions could be obtained using different pump powers in 20%Yb(3+)/1%Tm(3+)/1%Ho(3+) tri-doped NaYF4 micro-crystals at 980 nm excitation. The pump power-dependent intensity relationship was studied and relevant energy transfer processes were discussed in detail. The results suggest that Yb(3+)/Tm(3+) Ho(3+) tri-doped NaYF4 micro-crystals have potential applications in optoelectronic devices such as photovoltaic, plasma display panel and white-light-emitting diodes.

  15. Correlative near-infrared light and cathodoluminescence microscopy using Y2O3:Ln, Yb (Ln = Tm, Er) nanophosphors for multiscale, multicolour bioimaging

    PubMed Central

    Fukushima, S.; Furukawa, T.; Niioka, H.; Ichimiya, M.; Sannomiya, T.; Tanaka, N.; Onoshima, D.; Yukawa, H.; Baba, Y.; Ashida, M.; Miyake, J.; Araki, T.; Hashimoto, M.

    2016-01-01

    This paper presents a new correlative bioimaging technique using Y2O3:Tm, Yb and Y2O3:Er, Yb nanophosphors (NPs) as imaging probes that emit luminescence excited by both near-infrared (NIR) light and an electron beam. Under 980 nm NIR light irradiation, the Y2O3:Tm, Yb and Y2O3:Er, Yb NPs emitted NIR luminescence (NIRL) around 810 nm and 1530 nm, respectively, and cathodoluminescence at 455 nm and 660 nm under excitation of accelerated electrons, respectively. Multimodalities of the NPs were confirmed in correlative NIRL/CL imaging and their locations were visualized at the same observation area in both NIRL and CL images. Using CL microscopy, the NPs were visualized at the single-particle level and with multicolour. Multiscale NIRL/CL bioimaging was demonstrated through in vivo and in vitro NIRL deep-tissue observations, cellular NIRL imaging, and high-spatial resolution CL imaging of the NPs inside cells. The location of a cell sheet transplanted onto the back muscle fascia of a hairy rat was visualized through NIRL imaging of the Y2O3:Er, Yb NPs. Accurate positions of cells through the thickness (1.5 mm) of a tissue phantom were detected by NIRL from the Y2O3:Tm, Yb NPs. Further, locations of the two types of NPs inside cells were observed using CL microscopy. PMID:27185264

  16. Correlative near-infrared light and cathodoluminescence microscopy using Y2O3:Ln, Yb (Ln = Tm, Er) nanophosphors for multiscale, multicolour bioimaging.

    PubMed

    Fukushima, S; Furukawa, T; Niioka, H; Ichimiya, M; Sannomiya, T; Tanaka, N; Onoshima, D; Yukawa, H; Baba, Y; Ashida, M; Miyake, J; Araki, T; Hashimoto, M

    2016-01-01

    This paper presents a new correlative bioimaging technique using Y2O3:Tm, Yb and Y2O3:Er, Yb nanophosphors (NPs) as imaging probes that emit luminescence excited by both near-infrared (NIR) light and an electron beam. Under 980 nm NIR light irradiation, the Y2O3:Tm, Yb and Y2O3:Er, Yb NPs emitted NIR luminescence (NIRL) around 810 nm and 1530 nm, respectively, and cathodoluminescence at 455 nm and 660 nm under excitation of accelerated electrons, respectively. Multimodalities of the NPs were confirmed in correlative NIRL/CL imaging and their locations were visualized at the same observation area in both NIRL and CL images. Using CL microscopy, the NPs were visualized at the single-particle level and with multicolour. Multiscale NIRL/CL bioimaging was demonstrated through in vivo and in vitro NIRL deep-tissue observations, cellular NIRL imaging, and high-spatial resolution CL imaging of the NPs inside cells. The location of a cell sheet transplanted onto the back muscle fascia of a hairy rat was visualized through NIRL imaging of the Y2O3:Er, Yb NPs. Accurate positions of cells through the thickness (1.5 mm) of a tissue phantom were detected by NIRL from the Y2O3:Tm, Yb NPs. Further, locations of the two types of NPs inside cells were observed using CL microscopy. PMID:27185264

  17. Correlative near-infrared light and cathodoluminescence microscopy using Y2O3:Ln, Yb (Ln = Tm, Er) nanophosphors for multiscale, multicolour bioimaging

    NASA Astrophysics Data System (ADS)

    Fukushima, S.; Furukawa, T.; Niioka, H.; Ichimiya, M.; Sannomiya, T.; Tanaka, N.; Onoshima, D.; Yukawa, H.; Baba, Y.; Ashida, M.; Miyake, J.; Araki, T.; Hashimoto, M.

    2016-05-01

    This paper presents a new correlative bioimaging technique using Y2O3:Tm, Yb and Y2O3:Er, Yb nanophosphors (NPs) as imaging probes that emit luminescence excited by both near-infrared (NIR) light and an electron beam. Under 980 nm NIR light irradiation, the Y2O3:Tm, Yb and Y2O3:Er, Yb NPs emitted NIR luminescence (NIRL) around 810 nm and 1530 nm, respectively, and cathodoluminescence at 455 nm and 660 nm under excitation of accelerated electrons, respectively. Multimodalities of the NPs were confirmed in correlative NIRL/CL imaging and their locations were visualized at the same observation area in both NIRL and CL images. Using CL microscopy, the NPs were visualized at the single-particle level and with multicolour. Multiscale NIRL/CL bioimaging was demonstrated through in vivo and in vitro NIRL deep-tissue observations, cellular NIRL imaging, and high-spatial resolution CL imaging of the NPs inside cells. The location of a cell sheet transplanted onto the back muscle fascia of a hairy rat was visualized through NIRL imaging of the Y2O3:Er, Yb NPs. Accurate positions of cells through the thickness (1.5 mm) of a tissue phantom were detected by NIRL from the Y2O3:Tm, Yb NPs. Further, locations of the two types of NPs inside cells were observed using CL microscopy.

  18. Simultaneous size and luminescence control of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) microcrystals via Li+ doping

    NASA Astrophysics Data System (ADS)

    Lin, Hao; Xu, Dekang; Teng, Dongdong; Yang, Shenghong; Zhang, Yueli

    2015-07-01

    Enhancement of upconversion (UC) luminescence is imperative for the applications of UC microcrystals (MCs). In this work, NaYF4:Yb3+/RE3+ (RE = Tm, Ho) MCs via Li+ doping were successfully prepared by a simple hydrothermal process with the assistance of citric acid. The UC luminescence intensities of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) are significantly enhanced via Li+ doping at different concentrations. Compared to Li+-absent sample, UC luminescence intensities of blue emission (477 nm) and red emission (649 nm) in NaYF4:Yb3+/Tm3+ MCs via 15 mol% Li+ doping are improved by 10 and 9 times, respectively; UC luminescence intensities of green emission (538 nm) and red emission (644 nm) in NaYF4:Yb3+/Ho3+ MCs via 15 mol% Li+ doping are improved by 12 and 3 times, respectively. The mechanism of the enhancement via Li+ doping is discussed in details, which may be attributed to the fact that Li+ doping can cause the distortion of the local symmetry around RE ions. Our results indicate that the enhanced UC luminescence of NaYF4:Yb3+/RE3+ (RE = Tm, Ho) MCs via Li+ doping may have potential applications in optoelectronic devices such as solar cells and plasma display panel.

  19. Hydrothermal synthesis of Yb3+, Tm3+ co-doped Gd6MoO12 and its upconversion properties

    NASA Astrophysics Data System (ADS)

    Di, Qiu-Mei; Sun, Yu-Mei; Xu, Qi-Guang; Han, Liu; Xue, Bing; Sun, Jia-Yue

    2015-06-01

    Yb3+, Tm3+ co-doped Gd6MoO12 phosphors with different morphologies are prepared by the hydrothermal method. The dendrites present different morphologies (including hexagonal prisms, spindles, and spheres) after changing the pH value and edetate disodium (EDTA) usage. It is found that each of the two factors plays a crucial role in forming different morphologies. The up-conversion (UC) luminescence is studied. Under 980-nm semiconductor laser excitation, relatively strong blue emission and weak red emission are observed. Finally, the effect of pumping power on the UC luminescence properties and the level diagram mechanism of Gd6MoO12:Yb3+/Tm3+ phosphor are also discussed. Project supported by the National Natural Science Foundation of China (Grant No. 20976002), the Beijing Natural Science Foundation, China (Grant No. 2122012), the Key Projects for Science and Technology of Beijing Education Commission, China (Grant No. KZ201310011013), and the Education and Research Fund of Guangdong Province, China (Grant No. 2011B090400100).

  20. Uniform NaYF{sub 4}:Yb, Tm hexagonal submicroplates: Controlled synthesis and enhanced UV and blue upconversion luminescence

    SciTech Connect

    Huang, Wenjuan; Ding, Mingye; Huang, Hengming; Jiang, Chenfei; Song, Yan; Ni, Yaru; Lu, Chunhua; Xu, Zhongzi

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► β-NaYF{sub 4} phosphors as an excellent upconversion materials. ► Oleic acid can promote the transformation of α → β phase NaYF{sub 4}. ► The shape and size of β-NaYF{sub 4} submicroplate can be tuned by reactant concentration. ► Enhanced UV and blue peaks can be obtained by varying Yb{sup 3+} and Tm{sup 3+} concentration. -- Abstract: We reported the preparation of cubic (α-) and hexagonal (β-) NaYF{sub 4} particles in high boiling organic solvents 1-octadecene (ODE) and oleic acid (OA), through a thermal decomposition synthesis route. The as-prepared products were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), photoluminescence (PL) spectra. By tuning the OA/ODE volume ratio and reactant concentration, we could manipulate the morphology, size, and crystal structure of the products. Highly uniform β-NaYF{sub 4} submicroplates were obtained from α-NaYF{sub 4} nanoparticles by increasing the OA/ODE volume ratio, while the phase kept unchanged with the increasing of reactant concentration. Upconversion emissions from UV to NIR emissions were observed in β-NaYF{sub 4} hexagonal submicroplates under 980 nm laser diode excitation. In addition, the enhanced UV and blue upconversion emissions were obtained by varying Tm{sup 3+} and Yb{sup 3+} ion concentration.

  1. Hall and transverse even effects in the vicinity of a quantum critical point in Tm{sub 1-x}Yb{sub x}B{sub 12}

    SciTech Connect

    Sluchanko, N. E. Azarevich, A. N.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Anisimov, M. A.; Levchenko, A. V.; Filipov, V. B.; Shitsevalova, N. Yu.

    2012-09-15

    The angular, temperature, and magnetic field dependences of the resistance recorded in the Hall effect geometry are studied for the rare-earth dodecaboride Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions where the metal-insulator and antiferromagnetic-paramagnetic phase transitions are observed in the vicinity of the quantum critical point x{sub c} Almost-Equal-To 0.3. The measurements performed on high-quality single crystals in the temperature range 1.9-300 K for the first time have revealed the appearance of the second harmonic contribution, a transverse even effect in these fcc compounds near the quantum critical point. This contribution a is found to increase drastically both under the Tm-to-ytterbium substitution in the range x > x{sub c} and with an increase in the external magnetic field. Moreover, as the Yb concentration x increases, a negative peak of a significant amplitude appears on the temperature dependences of the Hall coefficient R{sub H}(T) for the Tm{sup 1-x}Yb{sub x}B{sub 12} compounds, in contrast to the invariable behavior R{sub H}(T) Almost-Equal-To const found for TmB{sub 12}. The complicated activation-type behavior of the Hall coefficient is observed at intermediate temperatures for x {>=} 0.5 with activation energies E{sub g}/k{sub B} Almost-Equal-To 200 K and E{sub a}/k{sub B} 55-75 K, and the sign inversion of R{sub H}(T) is detected at liquid-helium temperatures in the coherent regime. Renormalization effects in the electron density of states induced by variation of the Yb concentration are analyzed. The anomalies of the charge transport in Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions in various regimes (charge gap formation, intra-gap many-body resonance, and coherent regime) are discussed in detail and the results are interpreted in terms of the electron phase separation effects in combination with the formation of nanosize clusters of rare earth ions in the cage-glass state of the studied dodecaborides. The data obtained allow

  2. Remarkable enhancement of upconversion fluorescence and confocal imaging of PMMA Opal/NaYF(4):Yb(3+), Tm(3+)/Er(3+) nanocrystals.

    PubMed

    Yin, Ze; Zhu, Yongsheng; Xu, Wen; Wang, Jing; Xu, Sai; Dong, Biao; Xu, Lin; Zhang, Shuang; Song, Hongwei

    2013-05-01

    Novel PMMA opal photonic crystal/NaYF(4):Yb(3+), Tm(3+)/Er(3+) nanocrystal composites were fabricated and tremendous improvement in upconversion luminescence (UCL) was observed under infrared 980 nm excitation. They were also explored to improve brightness of cell images. PMID:23539518

  3. Investigation of upconversion luminescence in Yb3+/Tm3+/Ho3+ triply doped antimony-germanate glass and double-clad optical fiber

    NASA Astrophysics Data System (ADS)

    Zmojda, Jacek; Kochanowicz, Marcin; Miluski, Piotr; Righini, Giancarlo C.; Ferrari, Maurizio; Dorosz, Dominik

    2016-08-01

    The optical properties of novel antimony-germanate glass and optical fiber co-doped with Yb3+/Tm3+/Ho3+ ions were presented. White light luminescence in glass was observed as a result of energy transfer with upconversion between donor (Yb3+) and acceptors (Tm3+, Ho3+) ions under 976 nm excitation. The double-clad optical fiber with off-set core co-doped with Yb2O3/Tm2O3/Ho2O3 system was fabricated using a modified rod-in-tube technique. In glass co-doped with 0.5 mol%Yb2O3/0.1 mol%Tm2O3/0.2 mol%Ho2O3 the spectral distribution of three luminescence bands (478, 545 and 660 nm) corresponds to x = 0.35 and y = 0.32 CIE coordinates. In comparison to glass the optical fiber emission are located in the green region (CIE, x = 0.37, y = 0.49).

  4. Pulsed-laser-assisted synthesis of a Tm3+/Yb3+ co-doped CaMoO4 colloidal nanocrystal and its upconversion luminescence

    NASA Astrophysics Data System (ADS)

    Cho, Kyoungwon; Choi, Jaeha; Lee, Jung-Il; Ryu, Jeong Ho

    2016-01-01

    We report a novel synthetic route for the synthesis of Tm3+/Yb3+ co-doped calcium molybdate (CaMoO4) nanoparticles by using pulsed laser ablation in ethanol. The crystalline phase, particle morphology, particle size distribution, laser ablation mechanism, and upconversion (UC) luminescent properties are investigated. Stable colloidal suspensions consisting of well-dispersed Tm3+/Yb3+ co-doped CaMoO4 nanoparticles with a narrow size distribution could be obtained without any surfactant. Under 980-nm excitation, a Tm3+/Yb3+ co-doped nanocolloidal CaMoO4 suspension showed bright blue emission at a wavelength near 475 nm, which was generated by the 1G4 → 3H6 transition, and a weak red emission at a wavelength near 650 nm due to the 3F2 → 3H6 transition. The Tm3+/Yb3+ co-doped nanocrystalline CaMoO4 suspension exhibited a strong blue emission visible to the naked eyes, and a possible UC mechanism that depends on the pump-power dependence is discussed in detail.

  5. Lasing in a Tm : Yb{sub 3}Al{sub 5}O{sub 12} crystal pumped at 1.678 μm

    SciTech Connect

    Zavartsev, Yu D; Zagumennyi, A I; Kalachev, Yu L; Kutovoi, S A; Mikhailov, V A; Shcherbakov, I A

    2014-10-31

    The Yb{sub 3}Al{sub 5}O{sub 12} (YbAG) crystal is proposed as a matrix of Tm{sup 3+}-doped laser elements for two-micron lasers. A Tm : YbAG crystal of high optical quality is grown by the Czochralski method and its spectral and luminescent characteristics are studied. The luminescence decay time for the upper laser level {sup 3}F{sub 4} is measured to be 4.7 ms. Lasing in this crystal pumped by a 1.678-μm fibre laser is obtained at a wavelength of 2.02 μm for the first time. The total and slope efficiencies of the laser at room temperature and an output power up to 330 mW reach 33% and 41%, respectively. (lasers)

  6. Investigation on luminescence properties of Er3+-Yb3+-Tm3+ co-doped Gd2O3 hollow microspheres

    NASA Astrophysics Data System (ADS)

    Xu, Fang; Han, Wan-lei; Liu, Xiao-bo; Song, Ying-lin

    2011-06-01

    The Gd2O3 hollow microspheres have been successfully fabricated via carbonaceous polysaccharide microspheres as templates and urea as a precipitating agent, which involved the deposition of an inorganic coating on the surface of carbon microsphere, followed by heat treated 800°C for 4h. The obtained high uniform Gd2O3 microspheres with a spherical shape and hollow structure are uniform in size and distribution. The possible mechanism of evolution from glucose to carbonaceous polysaccharide microspheres and the chemical reaction of each step to form the final hollow spheres are proposed. The rare earth ion Ln3+ doped Gd2O3 (Ln = Er, Yb and Tm) hollow microspheres show bright up-conversion luminescence with different colors coming from different activator ions under ultraviolet or 980 nm light excitation, which may open new possibilities to synthesize other hollow spherical materials and extend their applications.

  7. Frequency upconversion luminescence from Yb{sup +3}-Tm{sup +3} codoped PbO-GeO{sub 2} glasses containing silver nanoparticles

    SciTech Connect

    Assumpcao, Thiago A. A.; Silva, Davinson M. da; Kassab, Luciana R. P.

    2009-09-15

    Infrared-to-visible and infrared-to-infrared frequency upconversion processes in Yb{sup 3+}-Tm{sup 3+} doped PbO-GeO{sub 2} glasses containing silver nanoparticles (NPs) were investigated. The experiments were performed by exciting the samples with a diode laser operating at 980 nm (in resonance with the Yb{sup 3+} transition {sup 2}F{sub 7/2}->{sup 2}F{sub 5/2}) and observing the photoluminescence (PL) in the visible and infrared regions due to energy transfer from Yb{sup 3+} to Tm{sup 3+} ions followed by excited state absorption in the Tm{sup 3+} ions. The intensified local field in the vicinity of the metallic NPs contributes for enhancement in the PL intensity at 480 nm (Tm{sup 3+}:{sup 1}G{sub 4}->{sup 3}H{sub 6}) and at 800 nm (Tm{sup 3+}:{sup 3}H{sub 4}->{sup 3}H{sub 6}).

  8. Investigation on upconversion luminescence properties of Gd2O3: Ho3+/Yb3+/Tm3+ nanotubes

    NASA Astrophysics Data System (ADS)

    Ye, Fei; Fang, Yu; Liu, Xiao-bo; Xu, Fang; Song, Ying-lin

    2013-09-01

    Lanthanide doped oxides nano materials have novel optical, physical and structural properties. Cubic Ho3+-Yb3+-Tm3+ co-doped Gd2O3 nanotubes are synthetize by a simple wet-chemical route at low temperature and ambient pressure followed by subsequent annealing heat treatment in muffle furnace. Nanotubes are formed by adjusting the pH value of reacting solution. The introduction of Yb3+ leads to strong visible upconversion luminescence and change the intensity ratio of the green, blue and red luminescence. In trichromatic laser display, research of how to enhance blue light is in the bottleneck period. In the experiment, the blue emission has been successfully improved. In certain doping ratio, distinct enhancement of blue emission and obvious degradation of green light have been observed, which is discussed in detail. X-Ray powder diffraction (XRD), scanning electron microscope (SEM) and upconversion (UC) emission spectra are used to characterize the sample. Strong and adjusted upconversion luminescence determine that the nano material is a potential candidate for applications of biological probe, color displays, lighting and photonics.

  9. van der Waals interactions and dipole polarizabilities of lanthanides: Tm(2F)-He and Yb(1S)-He potentials

    NASA Astrophysics Data System (ADS)

    Buchachenko, Alexei A.; Szczȩśniak, Małgorzata M.; Chałasiński, Grzegorz

    2006-03-01

    Anisotropic dipole polarizabilities of Tm(F2),Tm+2(F2), and Yb(S1) are calculated using the finite-field multireference averaged quadratic coupled cluster (MR-AQCC) (Tm and Tm+2) and RCCSD(T) (Yb) methods with small-core relativistic pseudopotentials ECP28MWB combined with the augmented ANO basis sets. The lanthanide atoms are strongly polarizable with the scalar part originating from the 6s electrons and the tensorial part from the open 4f shells. The adiabatic interaction potentials Σ+2,Π2,Δ2, and Φ2 of Tm(F2)-He and Tm+2(F2)-He were examined by the multireference approaches, multireference configuration interaction and MR-AQCC, using the basis sets designed in the polarizability calculations. A closed-shell lanthanide system Yb(S1)-He was included for comparison. The Tm-He Σ+2,Π2,Δ2, and Φ2 interaction potentials are very shallow and nearly degenerate (within 0.01cm-1), with the well depths in the range of 2.35-2.36cm-1 at R =6.17Å. The basis-set saturated well depths are expected to be larger by ca. 25%, as estimated using the bond-function augmented basis set. The interactions of lanthanide atoms with He are one order of magnitude less anisotropic than those involving first-row transition metal atoms. The suppression of anisotropy is chiefly attributed to the screening effected by the 6s shell. When these electrons are removed as in the di-cation complex Tm+2(F2)-He, the potentials deepen to a thousand wave number range and their anisotropy is enhanced 500-fold.

  10. Morphology control and multicolor up-conversion luminescence of GdOF:Yb3+/Er3+, Tm3+, Ho3+ nano/submicrocrystals.

    PubMed

    Zhang, Yang; Li, Xuejiao; Kang, Xiaojiao; Hou, Zhiyao; Lin, Jun

    2014-06-14

    In this paper, well defined GdOF:Yb(3+)/Er(3+), Tm(3+), Ho(3+) nano/submicrocrystals with multiform morphologies were prepared via the urea-based precipitation method without using any surfactants. The morphologies of the GdOF products, including spindles and spheres with different sizes (30-550 nm), could be easily modulated by changing the fluorine sources, and the possible formation mechanism has been presented. XRD, FT-IR, SEM, TEM, as well as up-conversion (UC) photoluminescence spectra were used to characterize the prepared samples. Under 980 nm NIR excitation, the relative emission intensities and emission colors of Yb(3+)/Er(3+), Yb(3+)/Tm(3+) and Yb(3+)/Ho(3+) doped GdOF could be precisely adjusted over a wide range by tuning the Yb(3+) doping concentration. The strategies for color tuning of UC emission proposed in the current system may be helpful to achieve efficient multicolor luminescence under 980 nm laser excitation. In addition, the corresponding UC mechanisms in the co-doping GdOF systems were analyzed in detail based on the emission spectra and the plot of luminescence intensity to pump power.

  11. Colour emission tunability in Ho3+-Tm3+-Yb3+ co-doped Y2O3 upconverted phosphor

    NASA Astrophysics Data System (ADS)

    Pandey, Anurag; Rai, Vineet Kumar

    2012-12-01

    The frequency upconversion (UC) emission throughout the visible region from the Y2O3:Ho3+-Tm3+-Yb3+ co-doped phosphors synthesized by using low temperature combustion process upon excitation with a diode laser operating at 980 nm have been presented. The colour emission tunability in co-doped phosphor has been observed on increasing the pump power and seen by the naked eyes. The tunability in colour emission has also been visualized by CIE chromaticity diagram. The variation in UC emission intensity of the 1G4 → 3H6 (Tm3+) and 5F3 → 5I8 (Ho3+) transitions lying in the blue region has been monitored with increase in the pump power and marked that their ratio can be used to determine the temperature. The developed phosphor has been used to record fingerprints. The observed most intense visible colour emission from the developed material may be used for photodynamic therapy and as an alternative of traditional fluorescent biolabels.

  12. Dissolution Mechanism of Upconverting AYF4:Yb,Tm (A = Na or K) Nanoparticles in Aqueous Media.

    PubMed

    Lisjak, Darja; Plohl, Olivija; Vidmar, Janja; Majaron, Boris; Ponikvar-Svet, Maja

    2016-08-16

    The dissolution of upconverting AYF4:Yb,Tm (A = Na or K) nanoparticles (UCNPs) in aqueous media was systematically studied. UCNPs with a cubic structure and sizes of between 10 and 33 nm were synthesized solvothermally in ethylene glycol at 200 °C. The UCNPs of both compositions showed an upconversion fluorescence emission characteristic of Tm(3+). The effects of the A cation, the particle size, the temperature, the pH, and the composition of the aqueous medium on the dissolution of the UCNPs were evaluated. The degree of dissolution was determined from the fraction of dissolved fluoride (F(-)) using potentiometry. Unexpectedly, the composition of aqueous media had the most significant effect on the dissolution of the UCNPs. The highest degree of dissolution and rate were measured for the phosphate-buffered saline (PBS), which can be explained by the formation of stable lanthanide compounds with phosphates. The degree of dissolution was much lower in water and in the phthalate buffer, which was attributed to the release of F(-) as a result of the hydrolysis of the UCNPs' surfaces. PMID:27459496

  13. Synthesis, structure, magnetism, and optical properties of theordered mixed-lanthanide sulfides gamma-LnLn'S3 (Ln=La, Ce; Ln'=Er, Tm,Yb)

    SciTech Connect

    Jin, G.B.; Choi, E.S.; Guertin, R.P.; Brooks, J.S.; Bray, T.H.; Booth, C.H.; Albrecht-Schmitt, T.E.

    2006-12-12

    {gamma}-LnLn{prime}S{sub 3} (Ln = La, Ce; Ln{prime} = Er, Tm, Yb) have been prepared as dark red to black single crystals by the reaction of the respective lanthanides with sulfur in a Sb{sub 2}S{sub 3} flux at 1000 C. This isotypic series of compounds adopts a layered structure that consists of the smaller lanthanides (Er, Tm, and Yb) bound by sulfide in six- and seven-coordinate environments that are connected together by the larger lanthanides (La and Ce) in eight- and nine-coordinate environments. The layers can be broken down into three distinct one-dimensional substructures containing three crystallographically unique Ln{prime} centers. The first of these is constructed from one-dimensional chains of edge-sharing [Ln{prime}S{sub 7}] monocapped trigonal prisms that are joined to equivalent chains via edge-sharing to yield ribbons. There are parallel chains of [Ln{prime}S{sub 6}] distorted octahedra that are linked to the first ribbons through corner-sharing. These latter units also share corners with a one-dimensional ribbon composed of parallel chains of [Ln{prime}S{sub 6}] polyhedra that edge-share both in the direction of chain propagation and with adjacent identical chains. Magnetic susceptibility measurements show Curie-Weiss behavior from 2 to 300 K with antiferromagnetic coupling, and no evidence for magnetic ordering. The {theta}{sub p} values range from -0.4 to -37.5 K, and spin-frustration may be indicated for the Yb-containing compounds. All compounds show magnetic moments substantially reduced from those calculated for the free ions. The optical band gaps for {gamma}-LaLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.6 eV, whereas {gamma}-CeLn{prime}S{sub 3} (Ln{prime} = Er, Tm, Yb) are approximately 1.3 eV.

  14. Tm3+/Yb3+ co-doped tellurite glass with silver nanoparticles for 1.85 μm band laser material

    NASA Astrophysics Data System (ADS)

    Huang, Bo; Zhou, Yaxun; Cheng, Pan; Zhou, Zizhong; Li, Jun; Jin, Wei

    2016-10-01

    Tm3+/Yb3+ co-doped tellurite glasses with different silver nanoparticles (Ag NPs) concentrations were prepared using the conventional melt-quenching technique and characterized by the UV/Vis/NIR absorption spectra, 1.85 μm band fluorescence emission spectra, transmission electron microscopy (TEM) images, differential scanning calorimeter (DSC) curves and X-ray diffraction (XRD) patterns to investigate the effects of Ag NPs on the 1.85 μm band spectroscopic properties of Tm3+ ions, thermal stability and structural nature of glass hosts. Under the excitation of 980 nm laser diode (LD), the 1.85 μm band fluorescence emission of Tm3+ ions enhances significantly in the presence of Ag NPs with average diameter of ∼8 nm and local surface Plasmon resonance (LSPR) band of ∼590 nm, which is mainly attributed to the increased local electric field induced by Ag NPs at the proximity of doped rare-earth ions on the basis of energy transfer from Yb3+ to Tm3+ ions. An improvement by about 110% of fluorescence intensity is observed in the Tm3+/Yb3+ co-doped tellurite glass containing 0.5 mol% amount of AgNO3 while the prepared glass samples possess good thermal stability and amorphous structural nature. Meanwhile, the Judd-Ofelt intensity parameters Ωt (t = 2,4,6), spontaneous radiative transition probabilities, fluorescence branching ratios and radiative lifetimes of relevant excited levels of Tm3+ ions were determined based on the Judd-Ofelt theory to reveal the enhanced effects of Ag NPs on the 1.85 μm band spectroscopic properties, and the energy transfer micro-parameters and phonon contribution ratios were calculated based on the non-resonant energy transfer theory to elucidate the energy transfer mechanism between Yb3+ and Tm3+ ions. The present results indicate that the prepared Tm3+/Yb3+ co-doped tellurite glass with an appropriate amount of Ag NPs is a promising lasing media applied for 1.85 μm band solid-state lasers and amplifiers.

  15. Near-infrared to visible upconversion in Tm3+ and Yb3+ codoped Lu2O3 nanocrystals synthesized by hydrothermal method.

    PubMed

    Li, Li; Zhang, Xingli; Wei, Xiantao; Wang, Guangchuan; Guo, Changxin

    2014-06-01

    Lutetium oxide nanocrystals codoped with Tm3+ and Yb3+ have been successfully synthesized via adjusting the pH values of the precursor solution in a hydrothermal method followed by a subsequent calcination process. The samples were systematically characterized by X-ray diffraction, field-emission scanning microscopy, Fourier transform infrared transmittance spectroscopy, and upconversion luminescent spectra. The experimental results show that the pH values of the precursor solution have great effects on the structural, morphological, and upconversion luminescent properties of Lu2O3:2%Yb3+, 0.2%Tm3+ nanocrystals. The as-formed lutetium oxide precursors could transform to cubic Lu2O3 with the same morphology and a slight shrinkage in size after a calcination process. The upconversion emission intensity of Lu2O3:2%Yb3+, 0.2%Tm3+ nanocrystals obtained from the precursor solution with pH = 9 is the strongest. The enhancement of the upconversion luminescence is suggested to be the consequence of reducing the number of OH- groups and the enlarged nanocrystals size. Strong blue and weak red emissions from the prepared nanocrystals were observed under 980 nm laser excitation, which were attributed to the 1G4 --> 3H6 and 1G4 --> 3F4 transitions of Tm3+ ion, respectively.

  16. Survey and research on up-conversion emission character and energy transition of Yb3+/Er3+/Tm3+ co-doped phosphate glass and glass ceramic

    NASA Astrophysics Data System (ADS)

    Yu, Yin; Song, Feng; Ming, Chengguo; Liu, Jiadong; Li, Wei; Liu, Yanling; Zhao, Hongyan

    2012-11-01

    By conventional high-temperature melting method, Yb3+/Er3+/Tm3+ co-doped phosphate glass was synthesized. After annealing the precursor glass, the phosphate glass ceramic (GC) was obtained. By measuring the X-ray diffraction (XRD) spectrum, it is proved that the LiYbP4O12 and Li6P6O18 nano-crystals have existed in the phosphate GC. The up-conversion (UC) emission intensity of the GC is obvious stronger compared to that of the glass. The reason is that the shorter distance between rare earth ions in the glass ceramic increases the energy transitions from the sensitized ions (Yb3+) to the luminous ions (Er3+ and Tm3+). By studying the dependence of UC emissions on the pump power, the 523 and 546 nm green emissions of Er3+ ions in the glass are two-photon processes. But in the glass ceramic, they are two/three-photon processes. The phenomenon implies that a three-photon process has participated in the population of the two green emissions. Using Dexter theory, we discuss the energy transitions of Er3+ and Tm3+. The results indicate the energy transition of Tm3+ to Er3+ is very strong in the GC, which changes the population mechanism of UC emissions of Er3+.

  17. Anomalous Hall effect in three ferromagnetic compounds: EuFe4Sb12 , Yb14MnSb11 , and Eu8Ga16Ge30

    NASA Astrophysics Data System (ADS)

    Sales, Brian C.; Jin, Rongying; Mandrus, David; Khalifah, Peter

    2006-06-01

    The Hall resistivity (ρxy) , resistivity (ρxx) , and magnetization of three metallic ferromagnets are investigated as a function of magnetic field and temperature. The three ferromagnets, EuFe4Sb12 (Tc≈84K) , Yb14MnSb11 (Tc≈53K) , and Eu8Ga16Ge30 (Tc≈36K) are Zintl compounds with carrier concentrations between 1×1021 and 3.5×1021cm-3 . The relative decrease in ρxx below Tc [ρxx(Tc)/ρxx(2K)] is 28, 6.5, and 1.3 for EuFe4Sb12 , Yb14MnSb11 , and Eu8Ga16Ge30 , respectively. The low carrier concentrations coupled with low magnetic anisotropies allow a relatively clean separation between the anomalous (ρxy') , and normal contributions to the measured Hall resistivity. For each compound the anomalous contribution in the zero field limit is fit to aρxx+σxyρxx2 for temperatures TEuFe4Sb12 , Yb14MnSb11 , and Eu8Ga16Ge30 , respectively, and is independent of temperature for T

  18. Pressure variation of 4f excitation energies in Eu and Tm metals

    NASA Astrophysics Data System (ADS)

    Herbst, J. F.; Wilkins, J. W.

    1987-08-01

    Calculations of 4f-electron excitation energies as functions of the Wigner-Seitz radius rWS in europium and thulium metals are reported. Crystal potentials are constructed by the renormalized-atom method for integrally-occupied 4f configurations, and each excitation energy is derived from a difference of band total energies. As rWS decreases for each metal the 6s and 5d levels are progressively depopulated, leading to enhancement of the 4f occupancy at elevated pressures. In particular our results predict a 4f7-->4f8 transition in Eu at a pressure P~44 Mbar and a 4f12-->4f13 transition in Tm at P~3 Mbar.

  19. Higher thermoelectric performance of Zintl phases (Eu0.5Yb0.5)1-xCaxMg2Bi2 by band engineering and strain fluctuation.

    PubMed

    Shuai, Jing; Geng, Huiyuan; Lan, Yucheng; Zhu, Zhuan; Wang, Chao; Liu, Zihang; Bao, Jiming; Chu, Ching-Wu; Sui, Jiehe; Ren, Zhifeng

    2016-07-19

    Complex Zintl phases, especially antimony (Sb)-based YbZn0.4Cd1.6Sb2 with figure-of-merit (ZT) of ∼1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic "electron-crystal, phonon-glass" nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg2Bi2 with a record thermoelectric performance. Phase-pure EuMg2Bi2 is successfully prepared with suppressed bipolar effect to reach ZT ∼ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ∼1.3 for Eu0.2Yb0.2Ca0.6Mg2Bi2 at 873 K. Density-functional theory (DFT) simulation indicates the alloying has no effect on the valence band, but does affect the conduction band. Such band engineering results in good p-type thermoelectric properties with high carrier mobility. Using transmission electron microscopy, various types of strains are observed and are believed to be due to atomic mass and size fluctuations. Point defects, strain, dislocations, and nanostructures jointly contribute to phonon scattering, confirmed by the semiclassical theoretical calculations based on a modified Debye-Callaway model of lattice thermal conductivity. This work indicates Bi-based (Ca,Yb,Eu)Mg2Bi2 is better than the Sb-based Zintl phases. PMID:27385824

  20. Higher thermoelectric performance of Zintl phases (Eu0.5Yb0.5)1-xCaxMg2Bi2 by band engineering and strain fluctuation.

    PubMed

    Shuai, Jing; Geng, Huiyuan; Lan, Yucheng; Zhu, Zhuan; Wang, Chao; Liu, Zihang; Bao, Jiming; Chu, Ching-Wu; Sui, Jiehe; Ren, Zhifeng

    2016-07-19

    Complex Zintl phases, especially antimony (Sb)-based YbZn0.4Cd1.6Sb2 with figure-of-merit (ZT) of ∼1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic "electron-crystal, phonon-glass" nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg2Bi2 with a record thermoelectric performance. Phase-pure EuMg2Bi2 is successfully prepared with suppressed bipolar effect to reach ZT ∼ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ∼1.3 for Eu0.2Yb0.2Ca0.6Mg2Bi2 at 873 K. Density-functional theory (DFT) simulation indicates the alloying has no effect on the valence band, but does affect the conduction band. Such band engineering results in good p-type thermoelectric properties with high carrier mobility. Using transmission electron microscopy, various types of strains are observed and are believed to be due to atomic mass and size fluctuations. Point defects, strain, dislocations, and nanostructures jointly contribute to phonon scattering, confirmed by the semiclassical theoretical calculations based on a modified Debye-Callaway model of lattice thermal conductivity. This work indicates Bi-based (Ca,Yb,Eu)Mg2Bi2 is better than the Sb-based Zintl phases.

  1. Higher thermoelectric performance of Zintl phases (Eu0.5Yb0.5)1-xCaxMg2Bi2 by band engineering and strain fluctuation

    NASA Astrophysics Data System (ADS)

    Shuai, Jing; Geng, Huiyuan; Lan, Yucheng; Zhu, Zhuan; Wang, Chao; Liu, Zihang; Bao, Jiming; Chu, Ching-Wu; Sui, Jiehe; Ren, Zhifeng

    2016-07-01

    Complex Zintl phases, especially antimony (Sb)-based YbZn0.4Cd1.6Sb2 with figure-of-merit (ZT) of ˜1.2 at 700 K, are good candidates as thermoelectric materials because of their intrinsic “electron-crystal, phonon-glass” nature. Here, we report the rarely studied p-type bismuth (Bi)-based Zintl phases (Ca,Yb,Eu)Mg2Bi2 with a record thermoelectric performance. Phase-pure EuMg2Bi2 is successfully prepared with suppressed bipolar effect to reach ZT ˜ 1. Further partial substitution of Eu by Ca and Yb enhanced ZT to ˜1.3 for Eu0.2Yb0.2Ca0.6Mg2Bi2 at 873 K. Density-functional theory (DFT) simulation indicates the alloying has no effect on the valence band, but does affect the conduction band. Such band engineering results in good p-type thermoelectric properties with high carrier mobility. Using transmission electron microscopy, various types of strains are observed and are believed to be due to atomic mass and size fluctuations. Point defects, strain, dislocations, and nanostructures jointly contribute to phonon scattering, confirmed by the semiclassical theoretical calculations based on a modified Debye-Callaway model of lattice thermal conductivity. This work indicates Bi-based (Ca,Yb,Eu)Mg2Bi2 is better than the Sb-based Zintl phases.

  2. Enhancement of 2.0 μm fluorescence emission in new Ho3+/Tm3+/Yb3+ tri-doped tellurite glasses

    NASA Astrophysics Data System (ADS)

    Cheng, Pan; Yang, Feng-jing; Zhou, Zi-zhong; Huang, Bo; Wu, Li-bo; Zhou, Ya-xun

    2016-09-01

    For enhancing the 2.0 μm band fluorescence of Ho3+, a certain amount of WO3 oxide was introduced into Ho3+/Tm3+/Yb3+ tri-doped tellurite glass prepared using melt-quenching technique. The prepared tri-doped tellurite glass was characterized by the absorption spectra, fluorescence emission and Raman scattering spectra, together with the stimulated absorption, emission cross-sections and gain coefficient. The research results show that the introduction of WO3 oxide can further improve the 2.0 μm band fluorescence emission through the enhanced phonon-assisted energy transfers between Ho3+/Tm3+/Yb3+ ions under the excitation of 980 nm laser diode (LD). Meanwhile, the maximum gain coefficient of Ho3+ at 2.0 μm band reaches about 2.36 cm-1. An intense 2.0 μm fluorescence emission can be realized.

  3. Spin reorientation, magnetization reversal, and negative thermal expansion observed in R F e0.5C r0.5O3 perovskites (R =Lu ,Yb ,Tm )

    NASA Astrophysics Data System (ADS)

    Pomiro, Fernando; Sánchez, Rodolfo D.; Cuello, Gabriel; Maignan, Antoine; Martin, Christine; Carbonio, Raúl E.

    2016-10-01

    Three members of the perovskite family R F e0.5C r0.5O3 (R =Lu ,Yb , and Tm) have been synthesized and characterized. A systematic study of the crystal and magnetic structures was performed by neutron powder diffraction combined with magnetization measurements. All these compounds crystallize in a Pbnm orthorhombic unit cell and they are already antiferromagnetic at room temperature. The study of the magnetic structure vs temperature showed the occurrence of a progressive spin reorientation from Γ4TM to Γ2TM for the transition metal sublattice, and in the Tm-based sample, a long-range magnetic order of the T m3 + sublattice was found (Γ8R) . These results are in excellent agreement with the magnetic susceptibility measurements. No spin reorientation is observed in the Lu-based sample for which a magnetization reversal at a compensation temperature Tcomp= 225 K was detected. A clear magnetostrictive effect was observed in the samples with R =Yb and Tm associated with a negative thermal expansion and was assigned to a magnetoelastic effect produced by repulsion between the magnetic moments of neighboring transition metal ions.

  4. Lasing in a Tm:Ho:Yb3Al5O12 crystal pumped into the 3H6 - 3F4 transition

    NASA Astrophysics Data System (ADS)

    Zavartsev, Yu D.; Zagumennyi, A. I.; Kalachev, Yu L.; Kutovoi, S. A.; Mikhailov, V. A.; Shcherbakov, I. A.

    2016-03-01

    A growth technology has been developed, and a Tm:Ho:Yb3Al5O12 laser crystal of high optical quality has been grown by Czochralski method. Its spectral and luminescent characteristics are studied. Lasing at a wavelength of 2100 nm is obtained under pumping into the absorption line on the 3H6 - 3F4 transition of the Tm3+ ion at a wavelength of 1678 nm. The slope and total (optical) efficiencies of the laser at an output power of up to 320 mW reach 41% and 30%, respectively.

  5. Tuning upconversion luminescence of LiYF4:Yb3+,Er3+/Tm3+/Ho3+ microcrystals synthesized through a molten salt process.

    PubMed

    Niu, Na; He, Fei; Wang, Liuzhen; Wang, Lin; Wang, Yan; Gai, Shili; Yang, Piaoping

    2014-05-01

    In this paper, well-defined tetragonal-phase LiYF4:Yb3+,Er3+/Tm3+/Ho3+ micro-crystals with octahedral morphology were successfully prepared through a surfactant-free molten salt process for the first time. By gradually increasing the LiF content in the NaNO3-KNO3 reaction medium, the crystal phase transforms from a mixture of YF3 and LiYF4 to pure tetragonal-phase LiYF4. The possible formation process for the phase and morphology evolution is also presented. Moreover, upon 980 nm laser diode (LD) excitation, the lanthanide ions (Yb3+, Er3+/Tm3+/Ho3+) doped LiYF4 crystals exhibit intense upconversion emission lights. By tuning the sensitizer concentrations of Yb3+ ions in LiYF4:Yb3+,Er3+, the relative intensities of green and red emissions can be precisely adjusted under single wavelength excitation. Consequently, multicolor upconversion emissions can be obtained. On the other hand, UC mechanisms were also given based on the emission spectra and the plot of luminescence intensity to pump power.

  6. Ultraviolet upconversion enhancement in triply doped NaYF4:Tm3+, Yb3+ particles: The role of Nd3+ or Gd3+ Co-doping

    NASA Astrophysics Data System (ADS)

    Pokhrel, Madhab; Valdes, Carolina; Mao, Yuanbing

    2016-08-01

    Upconversion (UC) particles are currently under intensive investigation, normally for their visible instead of ultraviolet (UV) light luminescence under near-infrared (NIR) irradiation. As a commonly studied host, NaYF4 in particular is known to have low phonon energy and high UC efficiency. Here, we present our work on enhancing UC luminescence in the UV region by adding a third dopant into a binary-doped NaYF4:Yb3+,Tm3+ host. More specifically, neodymium (Nd3+) or gadolinium (Gd3+) ions was co-doped into parent NaYF4:20mol%Yb3+,0.5mol%Tm3+ UC particles to enhance their UV UC luminescence. Experimental results demonstrated that these particles exhibited the highest degree of UV UC enhancements when co-doped with 0.05mol% Nd3+ or 2.0mol% Gd3+, expanding the potential of this type of materials into many possible applications by directly converting NIR irradiation into UV light. Fundamentally, the UV UC emission dependence of these triply doped NaYF4:Yb3+,Tm3+ particles with different Nd3+ and Gd3+ doping concentrations was investigated in terms of ground state absorption, excited state absorption and energy transfer UC mechanisms.

  7. Specific features of magnetoresistance during the antiferromagnet-paramagnet transition in Tm{sub 1-x}Yb{sub x}B{sub 12}

    SciTech Connect

    Sluchanko, N. E. Azarevich, A. N.; Bogach, A. V.; Glushkov, V. V.; Demishev, S. V.; Levchenko, A. V.; Filippov, V. B.; Shitsevalova, N. Yu.

    2013-05-15

    The transverse magnetoresistance {Delta}{rho}/{rho}(H, T) of Tm{sub 1-x}Yb{sub x}B{sub 12} single crystals is studied in the ytterbium concentration range corresponding to the antiferromagnet-paramagnet transition in a magnetic field up to 80 kOe at low temperatures. A magnetic H-T phase diagram is constructed for the antiferromagnetic state of substitutional Tm{sub 1-x}Yb{sub x}B{sub 12} solid solutions with x {<=} 0.1. The contributions to the magnetoresistance in the antiferromagnetic and paramagnetic phases of the dodecaborides under study are separated. Along with negative quadratic magnetoresistance -{Delta}{rho}/{rho} {proportional_to} H{sub 2}, the magnetically ordered phase of these compounds is found to have component {Delta}{rho}/{rho} {proportional_to} H that linearly changes in a magnetic field. The negative contribution to the magnetoresistance of Tm{sub 1-x}Yb{sub x}B{sub 12} is analyzed in terms of the Yosida model for a local magnetic susceptibility.

  8. White upconversion of rare-earth doped ZnO nanocrystals and its dependence on size of crystal particles and content of Yb3+ and Tm3+

    NASA Astrophysics Data System (ADS)

    Liu, Yunxin; Xu, Changfu; Yang, Qibin

    2009-04-01

    Rare earth (RE) doped ZnO nanocrystals were synthesized by chemical combustion method. Bright white upconversion (UC) luminescence with the CIE coordinates close to (0.33, 0.33) was obtained in Er+Tm+Yb tridoped ZnO nanocrystals under the excitation of a cost-effective 980 nm single-wavelength laser diode. The overall and relative UC luminescence intensities of RE doped ZnO nanocrystals were found to be depended highly on the diameter of crystal particles and the concentration of Yb3+ and Tm3+, for which the involved mechanisms were demonstrated. The investigation based on UC spectra, simplified energy level diagram, and excitation power dependence indicated that the remarkable enhancement of the green emission of the RE tridoped sample was due to a dual sensitization of Er3+ by Yb3+ and Tm3+ ions. The RE tridoped ZnO nanocrystals with the CIE coordinates close to (0.33, 0.33) are potentially suitable for the widely realistic application as the multicolor fluorescent labels, due to a fact that they could be cheaply and easily obtained and excited cost effectively.

  9. White upconversion emission in Y{sub 2}O{sub 3}:Er{sup 3+}–Tm{sup 3+}–Yb{sup 3+}phosphor

    SciTech Connect

    Rai, Vineet Kumar; Dey, Riya; Kumar, Kaushal

    2013-06-01

    Graphical abstract: Schematic energy level diagram of Er{sup 3+}–Yb{sup 3+}–Tm{sup 3+} system upon excitation at 980 nm. Highlights: ► Prepared the Er{sup 3+}–Tm{sup 3+}–Yb{sup 3+} codoped Y{sub 2}O{sub 3} phosphor. ► Excitation of the sample by 980 nm diode laser is studied. ► Explored the possibility of getting white light emission from the synthesized phosphor. ► Colour tunability of the prepared phosphor is studied. ► Temperature sensing behaviour is investigated using FIR studied. - Abstract: Er{sup 3+}–Tm{sup 3+}–Yb{sup 3+} codoped Y{sub 2}O{sub 3} phosphor has been synthesized by optimized combustion synthesis process and its white light upconversion emission property is investigated using cheap 980 nm diode laser excitation. Efficient red, green and blue light emission bands, necessary for attaining white light emission, are observed in the codoped sample. The concentration of each rare earth ion is adjusted to get the required emission. In this phosphor, interestingly, emission colour coordinates are found to almost independent on the excitation power density. The temperature sensing behaviour of the prepared samples has also been studied using fluorescence intensity ratio (FIR) technique.

  10. Plasmonic enhanced emissions from cubic NaYF4:Yb: Er/Tm nanophosphors

    PubMed Central

    Sudheendra, L.; Ortalan, Volkan; Dey, Sanchita; Browning, Nigel D.; Kennedy, I.M.

    2011-01-01

    A metal shell was used in this study to provide significant enhancement of the up-converted emission from cubic NaYF4 nanoparticles, creating a valuable composite material for labeling in biology and other applications – use of the cubic form of the material obviates the need to undertake a high temperature transformation to the naturally more efficient hexagonal phase. The NaYF4 matrix contained ytterbium sensitizer and an Erbium (Er) or Thulium (Tm) activator. The particle sizes of the as-synthesized nanoparticles were in the range of 20–40 nm with a gold shell thickness of 4–8 nm. The gold shell was macroscopically amorphous. The synthesis method was based on a citrate chelation. In this approach, we exploited the ability of the citrate ion to act as a reductant and stabilizer. Confining the citrate ion reductant on the nanophosphor surface rather than in the solution was critical to the gold shell formation. The plasmonic shell enhanced the up-conversion emission of Tm from visible and near-infrared regions by up to a factor of 8, in addition to imparting a visible color arising from the plasmon absorption of the gold shell. The up-conversion enhancement observed with Tm and Er were different for similar gold coverages, with local crystal field changes as a possible route to enhance up-conversion emission from high symmetry structural hosts. These novel up-converting nanophosphor particles combine the phosphor and features of a gold shell, providing a unique platform for many biological imaging and labeling applications. PMID:21709812

  11. Effect of Li{sup +} ions on enhancement of near-infrared upconversion emission in Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals

    SciTech Connect

    Li Dongyu; Wang Yuxiao; Zhang Xueru; Dong Hongxing; Shi Guang; Liu Lu; Song Yinglin

    2012-11-01

    Near-infrared (NIR) to NIR upconversion emission is investigated in Tm{sup 3+}/Yb{sup 3+}/Li{sup +} triply doped Y{sub 2}O{sub 3} nanocrystals. Li{sup +} ions doped in Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals can greatly enhance the NIR upconversion emission intensity of Tm{sup 3+} ions. The abnormal shift of the (222) diffraction peak position determined from x-ray diffraction measurements is discussed, by introducing Li{sup +} ions in the Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals. The cause of the enhancement is the modification of the local symmetry induced by the Li{sup +} ions, which increases the intra-4f transitions of Tm{sup 3+} ion. Li{sup +} ions doped in Y{sub 2}O{sub 3}:Tm{sup 3+}/Yb{sup 3+} nanocrystals also can reduce the OH groups, dissociate the Yb{sup 3+} and Tm{sup 3+} ion clusters, and create the oxygen vacancies, which are the other reasons for enhancing the upconversion emission intensities. This material may be promising for in vitro and in vivo bioimaging probes.

  12. Dual-mode, tunable color, enhanced upconversion luminescence and magnetism of multifunctional BaGdF5:Ln(3+) (Ln = Yb/Er/Eu) nanophosphors.

    PubMed

    Li, Honglan; Liu, Guixia; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

    2016-08-01

    A series of Yb(3+), Er(3+), and Eu(3+) ions doped BaGdF5 dual-mode (down-conversion (DC) and upconversion (UC)) luminescent nanophosphors were successfully prepared by a simple one-step hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDS), Fourier-transform infrared (FTIR) spectroscopy, photoluminescence (PL) spectroscopy, fluorescence lifetime measurements, and vibrating sample magnetometry (VSM) were utilized to characterize the samples. Under 274 nm UV light excitation, BaGd0.78-zF5:0.2Yb(3+),0.02Er(3+),zEu(3+) phosphors emitted orange emission. Under 980 nm NIR irradiation, intense up-converted visible green emissions were observed in BaGdF5:Yb(3+),Er(3+)/Eu(3+) samples. The mechanism of UC emissions involved two-photon absorption. In the Yb(3+),Er(3+),Eu(3+) co-doped BaGdF5 phosphors, the energy transfer processes from Gd(3+) to Eu(3+) and from Yb(3+) to Er(3+) were discussed. Tunable colors were visualised with the help of the Commission Internationale de L'Eclairage (CIE) chromaticity diagram and the processes responsible for the DC and UC emissions were discussed in detail. The enhanced up-conversion luminescence of Yb(3+),Er(3+)/Eu(3+) co-doped BaGdF5 nanophosphors (NPs) was realized by modifying the trisodium citrate (Cit(3-)) surfactant. Moreover, the as-prepared samples exhibited paramagnetic properties at room temperature. This type of multifunctional orange-green emitting nanophosphor has promising applications in solid state lasers, lighting, MRI, anti-counterfeiting, biolabels, and so on.

  13. Dual-mode, tunable color, enhanced upconversion luminescence and magnetism of multifunctional BaGdF5:Ln(3+) (Ln = Yb/Er/Eu) nanophosphors.

    PubMed

    Li, Honglan; Liu, Guixia; Wang, Jinxian; Dong, Xiangting; Yu, Wensheng

    2016-08-01

    A series of Yb(3+), Er(3+), and Eu(3+) ions doped BaGdF5 dual-mode (down-conversion (DC) and upconversion (UC)) luminescent nanophosphors were successfully prepared by a simple one-step hydrothermal method. X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectrometry (EDS), Fourier-transform infrared (FTIR) spectroscopy, photoluminescence (PL) spectroscopy, fluorescence lifetime measurements, and vibrating sample magnetometry (VSM) were utilized to characterize the samples. Under 274 nm UV light excitation, BaGd0.78-zF5:0.2Yb(3+),0.02Er(3+),zEu(3+) phosphors emitted orange emission. Under 980 nm NIR irradiation, intense up-converted visible green emissions were observed in BaGdF5:Yb(3+),Er(3+)/Eu(3+) samples. The mechanism of UC emissions involved two-photon absorption. In the Yb(3+),Er(3+),Eu(3+) co-doped BaGdF5 phosphors, the energy transfer processes from Gd(3+) to Eu(3+) and from Yb(3+) to Er(3+) were discussed. Tunable colors were visualised with the help of the Commission Internationale de L'Eclairage (CIE) chromaticity diagram and the processes responsible for the DC and UC emissions were discussed in detail. The enhanced up-conversion luminescence of Yb(3+),Er(3+)/Eu(3+) co-doped BaGdF5 nanophosphors (NPs) was realized by modifying the trisodium citrate (Cit(3-)) surfactant. Moreover, the as-prepared samples exhibited paramagnetic properties at room temperature. This type of multifunctional orange-green emitting nanophosphor has promising applications in solid state lasers, lighting, MRI, anti-counterfeiting, biolabels, and so on. PMID:27424659

  14. NIR to blue light upconversion in Tm3+/Yb3+ codoped BaTiO3 tellurite glass

    NASA Astrophysics Data System (ADS)

    Kumari, Astha; Rai, Vineet Kumar

    2015-05-01

    Upconversion is an interesting optical property, generally shown by rare-earth doped materials. This unusual optical behavior shown by these rare-earths doped materials are due to their peculiar atomic configuration and electronic transitions. Here, the Tm3+-Yb3+ codoped BaTiO3 glass with TeO2 as former has been prepared by conventional melt and quench technique and the upconversion property has been investigated with the help of near infrared (NIR) to Visible UC study. The generation of the visible UC bands around ˜ 476 nm, ˜ 653 nm, ˜ 702 nm and one NIR UC band at ˜795 nm are assigned due to the 1G4→ 3H6, 1G4→ 3F4, 3F2→ 3H6 and 3H4→ 3H6 transitions respectively. The generations of these upconversion bands have been discussed in detail with the help of energy level diagram. The colour coordinates corresponding to the prepared material have been shown with the help of CIE chromaticity diagram. These glasses can be very appropriately used in the fabrication of solid state laser and as NIR to blue light upconverter.

  15. Influence of the Synthesis Parameters on the Properties of NaYF4:Yb3+,Tm3+ Nanoparticles.

    PubMed

    Plohl, Olivija; Majaron, Boris; Ponikvar-Svet, Maja; Makovec, Darko; Lisjak, Darja

    2015-01-01

    Fluorescent nanoparticles, especially fluorides, have received a great deal of interest due to their optical properties, making them suitable for applications in bio-imaging. For this reason they need to exhibit a superior chemical stability in aqueous media. We have studied the influence of the synthesis parameters on the chemical stability of NaYF(4) nanoparticles co-doped with Yb(3+) and Tm(3+). These nanoparticles have different crystal structures, and were synthesized hydrothermally or with thermal decomposition. The samples were characterized with X-ray diffraction and transmission electron microscopy. The up-conversion fluorescence of nanoparticles dispersed in water was measured at 400-900 nm. The partial dissolution of the fluorine in water was detected with an ion-selective electrode for all the samples. The dissolution of the other constituent ions was analysed with an optical emission spectrometer using inductively coupled plasma. The nanoparticles with a hexagonal crystal structure and sizes of around 20 nm that were synthesized with thermal decomposition showed a superior chemical stability in water together with a superior up-conversion fluorescence yield. PMID:26680706

  16. Eu/sup 2 +/, Yb/sup 2 +/, and Es/sup 2 +/ coordination with sodium tetraphenylborate in water-ethanol solutions

    SciTech Connect

    Mikheev, N.B.; Kulyukhin, S.A.; Rumer, I.A.; Kamenskaya, A.N.

    1988-11-01

    Measurements have been made on the coordination of divalent lanthanoid s and actinoids with sodium tetraphenylborate (NaTPB) in water-ethanol solutions. Ln/sup 2 +/ and An/sup 2 +/ form cationic and neutral complexes. The coordination constants ..beta../sub 1/ and ..beta../sub 2/ have been determine: 6.5 and 25.7 for Yb/sup 2 +/, 1.7 and 52.7 for Eu/sup 2 +/, and 6.2 and 106.4 for Es/sup 2 +/. The trend indicates that the hydrated Es/sup 2 +/ is smaller than Yb/sup 2 +/ and Eu/sup 2 +/.

  17. Upconversion luminescence and blackbody radiation in tetragonal YSZ co-doped with Tm(3+) and Yb(3+).

    PubMed

    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

  18. Upconversion luminescence and blackbody radiation in tetragonal YSZ co-doped with Tm3+ and Yb3+

    NASA Astrophysics Data System (ADS)

    Soares, M. R. N.; Ferro, M.; Costa, F. M.; Monteiro, T.

    2015-11-01

    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 Tm3+ and Yb3+ 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 Tm3+ (4f12) under resonant excitation into the high energy 2S+1LJ multiplets. Under NIR excitation (980 nm), the samples placed in air display an intense NIR at ~800 nm due to the 1G4 --> 3H5/3H4 --> 3H6 transitions. Additionally, red, blue/green and ultraviolet UCL is observed arising from higher excited 1G4 and 1D2 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 Tm3+, 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 non-contact pressure

  19. Multifunctional Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles synthesized by reverse micelle method

    PubMed Central

    Gavrilović, Tamara V.; Jovanović, Dragana J.; Lojpur, Vesna; Dramićanin, Miroslav D.

    2014-01-01

    Synthesis of Eu3+- and Er3+/Yb3+-doped GdVO4 nanoparticles in reverse micelles and their multifunctional luminescence properties are presented. Using cyclohexane, Triton X-100, and n-pentanol as the oil, surfactant, and co-surfactant, respectively, crystalline nanoparticles with ~4 nm diameter are prepared at low temperatures. The particle size assessed using transmission electron microscopy is similar to the crystallite size obtained from X-ray diffraction measurements, suggesting that each particle comprises a single crystallite. Eu3+-doped GdVO4 nanoparticles emit red light through downconversion upon UV excitation. Er3+/Yb3+-doped GdVO4 nanoparticles exhibit several functions; apart from the downconversion of UV radiation into visible green light, they act as upconvertors, transforming near-infrared excitation (980 nm) into visible green light. The ratio of green emissions from 2H11/2 → 2I15/2 and 4S3/2 → 4I15/2 transitions is temperature dependent and can be used for nanoscale temperature sensing with near-infrared excitation. The relative sensor sensitivity is 1.11%K−1, which is among the highest sensitivities recorded for upconversion-luminescence-based thermometers. PMID:24572638

  20. Up-conversion luminescence in germanate glass and double-clad optical fibre co-doped with Yb3+/Eu3+ ions

    NASA Astrophysics Data System (ADS)

    Kochanowicz, M.; Zmojda, J.; Ragin, T.; Miluski, P.; Jelen, P.

    2016-09-01

    In the paper the analysis of up-conversion (UC) luminescence in 0.5Yb2O3/(0.25-1)Eu2O3 (mol.%) co-doped germanate glass and optical fibre has been investigated. Up-conversion emission of bands at 591, 616, 652, 701 nm to which correspond Eu3+: 5D0 → 7F1, 5D0 → 7F2, 5D0 → 7F3, 5D0 → 7F4 transitions, respectively was obtained as a result of cooperative energy transfer between Yb3+ and Eu3+ ions. The highest up-conversion emission (Yb3+ → Eu3+ energy transfer efficiency η = 24%) was obtained in 0.5Yb2O3/0.75Eu2O3 co-doped glass. Comparison of up-conversion and down-conversion luminescence spectra of bulk glass, glass fibre and different length double-clad optical fibre (up to 5 m) showed subtle differences in shape of the spectrum. In comparison to down - conversion emission (λexc = 405 nm) main UC luminescence band is red-shifted by 2 nm and is characterized by 5 nm greater full - width half - maximum (FWHM).

  1. "White" phosphor on the basis of Gd2(MoO4)3: Tm,Tb,Eu single crystal

    NASA Astrophysics Data System (ADS)

    Sinitsyn, V. V.; Redkin, B. S.; Kiselev, A. P.; Shmurak, S. Z.; Kolesnikov, N. N.; Kveder, V. V.; Ponyatovsky, E. G.

    2015-08-01

    A single-crystal sample of Gd2(MoO4)3 simultaneously doped with europium, terbium and thulium is grown. The Tm, Tb and Eu dopants are employed as the luminescent centers emitting light in the red, green and blue ranges. Spectroscopy investigation reveals that simultaneous luminescence of the centers of all three types to produce white light occurs only under the sample excitation with ultraviolet (UV) light within the wavelength range 350 < λ < 370 nm. A commercial UV light-emitting diode (LED) with λLED = 365 nm is applied in order to show that the Gd2(MoO4)3:Tm,Tb,Eu crystal converts its UV flux into white light. So, it is demonstrated that white light may be produced using one matrix with luminous centers of three types.

  2. Role of the stimulated radiation of Yb3+ ions in the formation of luminescence of the Y0.8Yb0.2F3:Tm3+ solid solution

    NASA Astrophysics Data System (ADS)

    Mikheev, A. V.; Kazakov, B. N.

    2015-09-01

    A new mechanism has been proposed for the transfer of the energy of exciting laser radiation through the donor subsystem (Yb3+) to acceptors (Tm3+), which induces multiphoton transitions in the acceptor subsystem. The coherence of the induced radiation of donors is of key importance in this mechanism. An analytical dependence of the intensity of the up-conversion luminescence of Tm3+ (1G4 → 3H6) ions in the Y0.8Yb0.2F3:Tm3+ system on the pump power at the steady-state excitation by 934-nm infrared radiation of a laser diode has been obtained using the mathematical technique of the theory of Poisson processes. In contrast to known mechanisms, this dependence approximates the experimental dependence well in a wide power range (200-1200 mW). The proposed model is applicable for any system where the energy of pump radiation is transferred to acceptors through the subsystem of donor ions.

  3. Quantum sized Ag nanocluster assisted fluorescence enhancement in Tm{sup 3+}-Yb{sup 3+} doped optical fiber beyond plasmonics

    SciTech Connect

    Chattopadhyay, Rik; Haldar, Arindam; Paul, Mukul C.; Das, Shyamal; Bhadra, Shyamal K.

    2015-12-07

    We report a process for enhancing fluorescence emission from conventional rare earth ions in optical fiber by metal nanocluster (MNC) in nonresonant indirect pumping. The process is completely different from formal metal enhanced fluorescence phenomenon as the MNCs are too small in size to support localized surface plasmon and the excitation wavelength is far from plasmon resonance frequency. We used an established theory of two coupled oscillators to explain the simultaneous enhancement of Ytterbium (Yb{sup 3+}) and Thulium (Tm{sup 3+}) emission by silver (Ag) NCs under nonresonant pumping in optical fiber. The fiber is pumped with a 980 nm fiber pigtailed laser diode with input power of 20–100 mW to excite the Yb{sup 3+}. Four times enhancement of Yb{sup 3+} emission of 900–1100 nm and Tm{sup 3+} upconversion emission around 474 nm, 650 nm, and 790 nm is observed in the fiber with Ag NCs.

  4. Synthetic and spectroscopic studies of vanadate glaserites I: Upconversion studies of doubly co-doped (Er, Tm, or Ho):Yb:K{sub 3}Y(VO{sub 4}){sub 2}

    SciTech Connect

    Kimani, Martin M. Chen, Hongyu McMillen, Colin D. Anker, Jeffery N. Kolis, Joseph W.

    2015-03-15

    The synthesis and upconversion properties of trigonal glaserite-type K{sub 3}Y(VO{sub 4}){sub 2} co-doped with Er{sup 3+}/Yb{sup 3+}, Ho{sup 3+}/Yb{sup 3+}, or Tm{sup 3+}/Yb{sup 3+} were studied. Powder samples were synthesized by solid state reactions at 1000 °C for 48 h, while well-formed hexagonal single crystals of the same were grown hydrothermally using 10 M K{sub 2}CO{sub 3} at 560–650 °C. Infrared-to-visible upconversion by Er{sup 3+}/Yb{sup 3+}, Ho{sup 3+}/Yb{sup 3+}, or Tm{sup 3+}/Yb{sup 3+} codoped-K{sub 3}Y(VO{sub 4}){sub 2} glaserite powder and single crystals was observed, and the upconversion spectral properties were studied as a function of different Er{sup 3+}, Tm{sup 3+}, Ho{sup 3+}, and Yb{sup 3+} ion concentrations. The process is observed under 980 nm laser diode excitation and leads to strong green (552 nm) and red (659 nm) emission for Er{sup 3+}/Yb{sup 3+}, green (549 nm) and red (664 nm) emission for Ho{sup 3+}/Yb{sup 3+}, and blue (475 nm) and red (647 nm) emission for Tm{sup 3+}/Yb{sup 3+}. The main mechanism that allows for up-conversion is attributed the energy transfer among Yb{sup 3+} and the various Er{sup 3+}/Ho{sup 3+}/Tm{sup 3+} ions in excited states. These results illustrate the large potential of co-doped alkali double vanadates for photonic applications involving optoelectronics devices. - Graphical abstract: Synthesis and upconversion in vanadate glaserites. - Highlights: • K{sub 3}Y(VO{sub 4}){sub 2} codoped with Er, Tm, or Ho:Yb were synthesized via solid-state and hydrothermal routes. • Upconversion properties are investigated. • The codoped compounds revealed efficient infrared-to-visible upconversion. • The presented compounds are potential host for solid state lighting.

  5. Lanthanide stannate pyrochlores Ln{sub 2}Sn{sub 2}O{sub 7} (Ln = Nd, Sm, Eu, Gd, Er, Yb) nanocrystals: Synthesis, characterization, and photocatalytic properties

    SciTech Connect

    Wang, Wanjun; Liang, Shijing; Bi, Jinhong; Yu, Jimmy C.; Wong, Po Keung; Wu, Ling

    2014-08-15

    Highlights: • Ln{sub 2}Sn{sub 2}O{sub 7} (Ln = Nd, Sm, Eu, Gd, Er, Yb) are synthesized by hydrothermal method. • Light absorption edge shows red shift with decreasing Ln{sup 3+} radius from Nd{sup 3+} to Yb{sup 3+}. • Ln{sub 2}Sn{sub 2}O{sub 7} shows increasing photocatalytic activity with the decease of Ln{sup 3+} radius. • Electronic configuration reaches 4f{sup 14} under light irradiation may decrease photocatalytic activity. • Hydroxyl radicals are detected to be the major reactive species. - Abstract: A series of lanthanide stannate pyrochlores Ln{sub 2}Sn{sub 2}O{sub 7} (Ln = Nd, Sm, Eu, Gd, Er, Yb) nanocrystals have been successfully synthesized via a facile hydrothermal route. With the decrease of Ln{sup 3+} radius, the light absorption edge of the as-prepared Ln{sub 2}Sn{sub 2}O{sub 7} shows a red shift from Nd{sup 3+} to Yb{sup 3+}. Their photocatalytic activities are found to be improved with the decrease of Ln{sup 3+} radius. However, the photocatalytic activity of Yb{sub 2}Sn{sub 2}O{sub 7} is a little lower than Er{sub 2}Sn{sub 2}O{sub 7}, although the Yb{sup 3+} radius is smaller than Er{sup 3+}, which may be attributed to the full-filled electronic configuration (4f{sup 14}) of surface Yb{sup 2+} intermediates (formed by Yb{sup 3+} trapping a photo-excited electron). The crystallite size and surface area play the most important role in determining the activities. Furthermore, hydroxyl radicals are detected to be the major reactive species during the photo-degradation process. Our findings provide insights in the fabrication of highly efficient stannate photocatalysts, thus enlarging the family of photocatalysts available.

  6. Cooperative reduction by Ln(2+) and Cp*(-) ions: synthesis and properties of Sm, Eu, and Yb complexes with 3,6-di-tert-butyl-o-benzoquinone.

    PubMed

    Pushkarevsky, Nikolay A; Ogienko, Mikhail A; Smolentsev, Anton I; Novozhilov, Igor N; Witt, Alexander; Khusniyarov, Marat M; Cherkasov, Vladimir K; Konchenko, Sergey N

    2016-01-21

    The first examples of samarium, europium, and ytterbium complexes with 3,6-di-tert-butyl-o-benzoquinone(3,6-dbbq) in the form of catecholate have been obtained by reactions of the quinone with the corresponding lanthanocenes, [LnCp2*(thf)n] (n = 1 or 2) in solution. In the course of the reactions lanthanide ions lose one or two Cp* ligands, which take part in reduction of a quinone molecule into a catecholate anion (dbcat, 2(-)). As a result of the reactions, Sm and Yb clearly yield dimeric complexes[(LnCp*)2(dbcat)2], where each Ln ion loses one Cp* ligand. Eu forms a trimeric complex [(EuCp*)-(Eu·thf)2(dbcat)3], in which one Eu ion is coordinated by one Cp* ligand, while two Eu ions have lost all Cp* ligands and are coordinated by THF molecules instead. Magnetic properties corroborate the assignment of oxidation states made on the basis of single-crystal X-ray diffraction: all the quinone ligands are present in the catecholate state; both Sm/Yb ions in the dimers are in the +3 oxidation state, whereas the Eu trimer contains two Eu(II) and one Eu(III) ions. Cyclovoltammetry studies show the presence of two reversible oxidation waves for all complexes, presumably concerned with the redox transitions of the dbcat ligands.

  7. Cooperative reduction by Ln(2+) and Cp*(-) ions: synthesis and properties of Sm, Eu, and Yb complexes with 3,6-di-tert-butyl-o-benzoquinone.

    PubMed

    Pushkarevsky, Nikolay A; Ogienko, Mikhail A; Smolentsev, Anton I; Novozhilov, Igor N; Witt, Alexander; Khusniyarov, Marat M; Cherkasov, Vladimir K; Konchenko, Sergey N

    2016-01-21

    The first examples of samarium, europium, and ytterbium complexes with 3,6-di-tert-butyl-o-benzoquinone(3,6-dbbq) in the form of catecholate have been obtained by reactions of the quinone with the corresponding lanthanocenes, [LnCp2*(thf)n] (n = 1 or 2) in solution. In the course of the reactions lanthanide ions lose one or two Cp* ligands, which take part in reduction of a quinone molecule into a catecholate anion (dbcat, 2(-)). As a result of the reactions, Sm and Yb clearly yield dimeric complexes[(LnCp*)2(dbcat)2], where each Ln ion loses one Cp* ligand. Eu forms a trimeric complex [(EuCp*)-(Eu·thf)2(dbcat)3], in which one Eu ion is coordinated by one Cp* ligand, while two Eu ions have lost all Cp* ligands and are coordinated by THF molecules instead. Magnetic properties corroborate the assignment of oxidation states made on the basis of single-crystal X-ray diffraction: all the quinone ligands are present in the catecholate state; both Sm/Yb ions in the dimers are in the +3 oxidation state, whereas the Eu trimer contains two Eu(II) and one Eu(III) ions. Cyclovoltammetry studies show the presence of two reversible oxidation waves for all complexes, presumably concerned with the redox transitions of the dbcat ligands. PMID:26674171

  8. Up-conversion emission in triply-doped Ho3+/Yb3+/Tm3+ KGd(WO4)2 single crystals

    NASA Astrophysics Data System (ADS)

    Kasprowicz, D.; Brik, M. G.; Majchrowski, A.; Michalski, E.; Głuchowski, P.

    2011-06-01

    Detailed spectroscopic studies of the triply doped KGd(WO4)2:Ho3+/Yb3+/Tm3+ single crystals (which exhibit multicolor up-conversion fluorescence) are reported for the first time. The absorption spectra of crystals were measured at 10 and 300 K; the room temperature luminescence spectra were excited at 980 nm wavelength. The dependence of the intensity of luminescence on the excitation power for three different concentration of Ho3+, Yb3+ and Tm3+ ions was investigated. Efficient green and red up-converted luminescence of Ho3+ ions and weak blue up-conversion luminescence of Tm3+ ions were observed in spectra. The red emission of Ho3+ ions is more intensive than their green emission. Dependence of the up-conversion luminescence intensity on the excitation power and impurities concentration was also studied; the number of phonon needed for efficient up-conversion was determined for each case. All possible energy transfer processes between different pairs of the impurity ions' energy levels are also discussed.

  9. [The Synthesis, Luminescence and Energy Transmission of NaLa(MoO4) 2 : Eu3+/Tb3+/Tm3+ Materials].

    PubMed

    Xu, Jing; Yan, Jing-hui; Han, Yu-ting; Qiao, Shu-liang; Yang, Bo; Li, Li; Liu, Cai-hong; Yau, Shuang; Zou, Ming-qiang

    2015-10-01

    A series of Eu3+ /Tb3+ /Tm3+ single/co-doped NaLa(MoO4)2 (NLM) phosphors have been synthesized by microemulsion-hydrothermal method. Phosphor crystal structure, morphology and luminescent properties were tested and studied by X-ray diffraction (XRD), scanning electron microscopy (SEM) and fluorescence spectroscopy. The results show that the prepared samples are all tetragonal single crystals. By way of substitution, the sites of La3+ are replaced by Eu3+, Tb3+ and Tm3+. Morphology of the samples are tetragonal sheet structure and the size of particles is 1 - 1.5 μm. When the doping concentration of Eu3+ is 9%, NLM : 9%Eu3+ phosphor emission peak is the strongest at 616 nm, the critical transfer distance (R(c)) between Eu3+ in the NLM matrix is about 15.20 Å at this time. At the emission spectrum of NLM : 9%Eu3+, the peak at 591 nm is the magnetic dipole transition of 5D0 to 7F1 of Eu3+. The peak at 616 nm is the electric dipole transition of 5D0 to 7 F2 of Eu3+. Electric dipole transition emission intensity is about 10 times of the strength of the magnetic dipole transition. This indicates that Eu3+ is located at noninversion symmetry site. By Fixing Eu3+ (Tb3+) concentration and varying the concentration of Tb3+ (Eu3+), the energy transfer mechanism between Eu3+ and Tb3+ was studied. By adjusting the Eu3+, Tb3+ and Tm3+ doping concentrations, tunable luminescence of visible light region is implemented under the single matrix. The luminescence of NLM x%Eu3+, y%Tb3+, z%Tm3+ phosphors are translated from blue (0.205, 0.135) to pseudo-white (0.305, 0.266) under 360 nm irradiation. PMID:26904805

  10. Investigation on up-conversion luminescence properties of novel transparent Ho3+-Tm3+-Yb3+ co-doped oxyfluoride glass ceramics

    NASA Astrophysics Data System (ADS)

    Liu, Xiao-bo; Han, Wan-lei; Xu, Fang; Song, Ying-lin

    2011-06-01

    In the present letter, the transparent oxyfluoride glass ceramics containing Ho3+-Tm3+-Yb3+:NaYF4 were successfully prepared by melt-quenching at 1400°C and subsequent heating at 650-680°C for 1~2 hours . X-ray diffraction (XRD) with Cu Kα radiation (λ=0.154nm) investigation revealed that NaYF4 nano-crystals in the glass ceramics was fabricated. Their sizes were determined by Sherrer's equation. The emission spectra red green and blue up-conversion (UC) under 980nm laser diode (LD) pumping and absorption spectra were measured. Luminescence measurements confirmed the partition of RE ions in nano-crystals NaYF4. The blue red and green UC radiations correspond to the transitions 1G4-3H6, 1G4-3H4 of Tm3+, 5F4, 5S2-5I8, 5F5-5I8, of Ho3+ ions, respectively. This is similar to that in Tm3+-Yb3+ and/or Ho3+-Yb3+ co-doped glass ceramics. To obtain upconversion fluorescence mechanisms, upconversion fluorescence intensity versus LD pump power were analyzed in view of energy levels of rare earth. Up-conversion mechanisms were discussed and the ratio between red, green and blue UC emission bands was found to be varied as a function of temperature of heat treatment and pump power. This result could be mainly attributed to the cross-relaxation between Ho3+ ions. The excellent optical properties and its convenient, low-cost synthesis of the present glass ceramic imply that it is an excellent substitution material for the unobtainable bulk NaYF4 crystal and may have potentially applications in tunable visible laser or many other fields.

  11. Depositing CdS nanoclusters on carbon-modified NaYF4:Yb,Tm upconversion nanocrystals for NIR-light enhanced photocatalysis

    NASA Astrophysics Data System (ADS)

    Tou, Meijie; Mei, Yuanyuan; Bai, Song; Luo, Zhenguo; Zhang, Yong; Li, Zhengquan

    2015-12-01

    High-quality hexagonal NaYF4:Yb,Tm upconversion nanocrystals (UCNs) prepared in organic solutions display uniform sizes and strong UC emissions, but they possess a hydrophobic surface which hinders combining them with various semiconductor nanocrystals (NCs) to form a hybrid NIR-activated photocatalyst. Herein we present a facile approach to modify hydrophobic UCNs with a uniform carbon layer and enable them with hydrophilicity and surface functionalization. The carbon shell provides a good substrate for enriching with metal ions and in situ generation of CdS nanoclusters on the particle surface which can utilize both the upconverted UV and visible emissions. The developed NaYF4:Yb,Tm@C@CdS nanoparticles are characterized with TEM, SEM, XRD, PL and UV-Vis spectra and their formation mechanism is elucidated. The products display good photocatalytic activity under visible light and obviously enhanced performance under Vis-NIR light, due to the efficient utilization of UC emissions and the strong adsorption capacity of the carbon shell. The working mechanism of the hybrid photocatalysts is also proposed.High-quality hexagonal NaYF4:Yb,Tm upconversion nanocrystals (UCNs) prepared in organic solutions display uniform sizes and strong UC emissions, but they possess a hydrophobic surface which hinders combining them with various semiconductor nanocrystals (NCs) to form a hybrid NIR-activated photocatalyst. Herein we present a facile approach to modify hydrophobic UCNs with a uniform carbon layer and enable them with hydrophilicity and surface functionalization. The carbon shell provides a good substrate for enriching with metal ions and in situ generation of CdS nanoclusters on the particle surface which can utilize both the upconverted UV and visible emissions. The developed NaYF4:Yb,Tm@C@CdS nanoparticles are characterized with TEM, SEM, XRD, PL and UV-Vis spectra and their formation mechanism is elucidated. The products display good photocatalytic activity under

  12. Optical properties of trigonal single crystals (Yb,Tm)Al{sub 3}(BO{sub 3}){sub 4} grown from fluxes based on the bismuth and lithium molybdates

    SciTech Connect

    Temerov, V. L. Sokolov, A. E.; Sukhachev, A. L.; Bovina, A. F.; Edel'man, I. S.; Malakhovskii, A. V.

    2008-12-15

    The conditions for synthesis of Yb{sub x}Tm{sub 1-x}Al{sub 3}(BO{sub 3}){sub 4} (x = 0, 0.1, 0.2, 1.0) single crystals from fluxes based on bismuth trimolybdate Bi{sub 2}Mo{sub 3}O{sub 12} and lithium molybdate Li{sub 2}MoO{sub 4} are investigated. It is proposed to grow them by the group method on seeds. The polarized optical absorption spectra are measured for two mutually orthogonal linear polarizations at temperatures of 100 and 300 K.

  13. An experimental design approach for hydrothermal synthesis of NaYF4: Yb3+, Tm3+ upconversion microcrystal: UV emission optimization

    NASA Astrophysics Data System (ADS)

    Kaviani Darani, Masoume; Bastani, Saeed; Ghahari, Mehdi; Kardar, Pooneh

    2015-11-01

    Ultraviolet (UV) emissions of hydrothermally synthesized NaYF4: Yb3+, Tm3+ upconversion crystals were optimized using the response surface methodology experimental design. In these experimental designs, 9 runs, two factors namely (1) Tm3+ ion concentration, and (2) pH value were investigated using 3 different ligands. Introducing UV upconversion emissions as responses, their intensity were separately maximized. Analytical methods such as XRD, SEM, and FTIR could be used to study crystal structure, morphology, and fluorescent spectroscopy in order to obtain luminescence properties. From the photo-luminescence spectra, emissions centered at 347, 364, 452, 478, 648 and 803 nm were observed. Some results show that increasing each DOE factor up to an optimum value resulted in an increase in emission intensity, followed by reduction. To optimize UV emission, as a final result to the UV emission optimization, each design had a suggestion.

  14. Multicolour upconversion emission from Ho{sup 3+}-Tm{sup 3+}-Yb{sup 3+} codoped CaMoO{sub 4} phosphor

    SciTech Connect

    Dey, Riya; Rai, Vineet Kumar

    2015-05-15

    The Ho{sup 3+}-Tm{sup 3+}-Yb{sup 3+} codoped CaMoO4 phosphor powder has been synthesized by chemical coprecipitation technique. For the structural investigation the X-ray diffraction analysis has been done. Multicolour upconversion (UC) emission in the visible region from the prepared material has been observed under the 980 nm near infrared (NIR) excitation. The UC emission bands ∼ 474 nm (blue), ∼ 541 nm (green) and ∼ 661 nm (red) region have been assigned as {sup 1}G{sub 4}→{sup 3}H{sub 6} (Tm{sup 3+}), {sup 5}F{sub 4}{sup 5}S{sub 2}→{sup 5}I{sub 8} (Ho{sup 3+}) and {sup 5}F{sub 5}→{sup 5}I{sub 8} (Ho{sup 3+}) transitions respectively.

  15. Intense upconversion luminescence and effect of local environment for Tm 3+/Yb 3+ co-doped novel TeO 2-BiCl 3 glass system

    NASA Astrophysics Data System (ADS)

    Wang, Guonian; Dai, Shixun; Zhang, Junjie; Wen, Lei; Yang, Jianhu; Jiang, Zhonghong

    2006-05-01

    We present the results of a study that uses theoretical and experimental methods to investigate the characteristics of the upconversion luminescence of Tm 3+/Yb 3+ codoped TeO 2-BiCl 3 glass system as a function of the BiCl 3 fraction. These glasses are potentially important in the design of upconversion fiber lasers. Effect of local environment around Tm 3+ on upconversion fluorescence intensity was analyzed by theoretical calculations. The structure and spectroscopic properties were investigated in the experiments by measuring the Raman spectra, IR transmission spectra, and absorption and fluorescence intensities at room temperature. The results indicate that blue luminescence quantum efficiency increases with increasing BiCl 3 content from 10 to 60 mol%, which were interpreted by the increase of asymmetry of glass structure, decrease of phonon energy and removing of OH - groups.

  16. Activation of SO2 with [(η(5) -C5 Me5 )2 Ln(THF)2 ] (Ln=Eu, Yb) leading to dithionite and sulfinate complexes.

    PubMed

    Klementyeva, Svetlana V; Gamer, Michael T; Schmidt, Anna-Corina; Meyer, Karsten; Konchenko, Sergey N; Roesky, Peter W

    2014-10-13

    The reaction of decamethylytterbocene [(η(5) -C5 Me5 )2 Yb(THF)2 ] with SO2 at low temperature gave two new compounds, namely, the Yb(III) dithionite/sulfinate complex [{(η(5) -C5 Me5 )2 Yb(μ3 ,1κ(2) O(1,3) ,2κ(3) O(2,2',4) -S2 O4 )}2 {(η(5) -C5 Me5 )Yb(μ,1κO,2κO'-C5 Me5 SO2 )}2 ] (1) and the Yb(III) dithionite complex [{(η(5) -C5 Me5 )2 Yb}2 (μ,1κ(2) O(1,3) ,2κ(2) O(2,4) -S2 O4 )] (2). After extraction of 1, the mixture was heated to give the dinuclear tetrasulfinate complex [{(η(5) -C5 Me5 )Yb}2 (μ,κO,κO'-C5 Me5 SO2 )4 ] (3 a). In contrast, from the reaction of [(η(5) -C5 Me5 )2 Eu(THF)2 ] with SO2 only the tetrasulfinate complex [{(η(5) -C5 Me5 )Eu}2 (μ,κO,κO'-C5 Me5 SO2 )4 ] (3 b) was isolated. Two major reaction pathways were observed: 1) reductive coupling of two SO2 molecules to form the dithionite anion S2 O4 (2-) ; and 2) nucleophilic attack of one metallocene C5 Me5 ligand on the sulfur atom of SO2 . The compounds presented are the first dithionite and sulfinate complexes of the f-elements.

  17. Highly improved upconversion luminescence in NaGd(WO₄)₂:Yb³⁺/Tm³⁺ inverse opal photonic crystals.

    PubMed

    Wang, Yunfeng; Xu, Wen; Cui, Shaobo; Xu, Sai; Yin, Ze; Song, Hongwei; Zhou, Pingwei; Liu, Xiaoyan; Xu, Lin; Cui, Haining

    2015-01-28

    The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb(3+)/Tm(3+) inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm(3+) ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL (1)D2-(3)H6/(3)F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm(3+) was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm(3+) was largely improved due to the periodic macroporous structure.

  18. Highly improved upconversion luminescence in NaGd(WO₄)₂:Yb³⁺/Tm³⁺ inverse opal photonic crystals.

    PubMed

    Wang, Yunfeng; Xu, Wen; Cui, Shaobo; Xu, Sai; Yin, Ze; Song, Hongwei; Zhou, Pingwei; Liu, Xiaoyan; Xu, Lin; Cui, Haining

    2015-01-28

    The upconversion luminescence (UCL) of rare earth (RE) ions doped nanomaterials has attracted extensive interest because of its wide and great potential applications. However, the lower UCL efficiency is still an obstacle for real applications. Photonic modulation is a novel way to improve the efficiency of UCL. In this work, NaGd(WO4)2:Yb(3+)/Tm(3+) inverse opal photonic crystals (IOPCs) were fabricated through the polymethylmethacrylate (PMMA) template and the modification of the IOPC structure on the emission spectra and dynamics of Tm(3+) ions was systemically studied. It is interesting to observe that in the IOPCs, the high-order UCL (1)D2-(3)H6/(3)F4 was relatively enhanced. At the same time, the local thermal effect induced by laser irradiation was suppressed. Furthermore, the overall intensity ratio of visible UCL to near-infrared (NIR) down-conversion luminescence (DCL) was 2.8-8 times improved than that of the grinded reference (REF) and independent of the photonic stop band (PSB). The studies on UCL dynamics indicated that the nonradiative transition rate of Tm(3+) was considerably suppressed. The facts above indicated that in the IOPCs the UCL efficiency of Tm(3+) was largely improved due to the periodic macroporous structure. PMID:25493336

  19. Hydrothermal synthesis of BaYbF5:Tm3+ nanoparticles for dual-modal upconversion near-infrared luminescence and magnetic resonance imaging

    NASA Astrophysics Data System (ADS)

    Liu, Ping; Miu, Wei

    2016-04-01

    In this paper, we demonstrate multifunctional upconversion nanoparticles with intense near-infrared emission and unique magnetic properties for dual-modal upconversion luminescent bioimaging and T2-weighted magnetic resonance imaging. High-quality BaYbF5:Tm3+ nanoparticles are synthesized via a hydrophobic method and then converted to be hydrophilic via a hydrochloric acid treatment. The as-synthesized nanoparticles are cubic phase and about 6 nm in diameter with narrow size distribution. The intense near-infrared emission makes these nanoparticles can be acted as bio-probes in upconversion luminescent bioimaging with deep tissue penetration. Besides, these nanoparticles can also be used as T2-weighted contrast agents in magnetic resonance imaging due to the high value of relaxation rate (r2 = 4.05) in 0.55 T. This finding may have further bio-applications in the future due to the high performance of these BaYbF5:Tm3+ nanoparticles in dual-modal bioimaging.

  20. The Crystal Structure of Impurity Centers Tm^{2+} and Eu^{2+} in SrCl2 : Ab Initio Calculations

    NASA Astrophysics Data System (ADS)

    Chernyshev, V. A.; Serdcev, A. V.; Petrov, V. P.; Nikiforov, A. E.

    2016-01-01

    Ab initio calculations of the impurity centers Tm^{2+} thulium and europium Eu^{2+} in SrCl2 and MeF2 (Me = Ca, Sr, Ba) were carried out at low (zero) temperature. The crystal structure of impurity centers was investigated. Charge density maps show that the bonds formed by the rare-earth ions have an ionic character. The crystal structures, lattice dynamics, and band structures of MeF2 and SrCl2 were calculated at low temperature. Ab initio calculations were performed in periodic CRYSTAL code within the framework of the MO LCAO approach by using hybrid DFT functionals.

  1. Effect of C6+ Ion Irradiation on structural and electrical properties of Yb and Eu doped Bi1.5 Zn0.92 Nb1.5 O6.92 pyrochlores

    NASA Astrophysics Data System (ADS)

    Yumak, Mehmet; Mergen, Ayhan; Qureshi, Anjum; Singh, N. L.

    2015-03-01

    Pyrochlore general formula of A2B2X7 where A and B are cations and X is an anion Pyrochlore compounds exhibit semiconductor, metallic or ionic conduction properties, depending on the doping, compositions/ substituting variety of cations and oxygen partial pressure. Ion beam irradiation can induce the structural disordering by mixing the cation and anion sublattices, therefore we aim to inevestigate effects of irradiation in pyrochlore compounds. In this study, Eu and Yb-doped Bi1.5Zn0.92Nb1.5O6.92 (Eu-BZN, Yb-BZN) Doping effect and single phase formation of Eu-BZN, Yb-BZN was characterized by X-ray diffraction technique (XRD). Radiation-induced effect of 85 MeV C6+ ions on Eu-BZN, Yb-BZN was studied by XRD, scanning electron microscopy (SEM) and temperature dependent dielectric measurements at different fluences. XRD results revealed that the ion beam-induced structural amorphization processes in Eu-BZN and Yb-BZN structures. Our results suggested that the ion beam irradiation induced the significant change in the temprature depndent dielectric properties of Eu-BZN and Yb-BZN pyrochlores due to the increased oxygen vacancies as a result of cation and anion disordering. Department of Metallurgical and Materials Eng., Marmara University, Istanbul-81040, Turkey.

  2. The action mechanism of TiO{sub 2}:NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} cathode buffer layer in highly efficient inverted organic solar cells

    SciTech Connect

    Liu, Chunyu; Chen, Huan; Zhao, Dan; Shen, Liang; He, Yeyuan; Guo, Wenbin E-mail: chenwy@jlu.edu.cn; Chen, Weiyou E-mail: chenwy@jlu.edu.cn

    2014-08-04

    We report the fabrication and characteristics of organic solar cells with 6.86% power conversion efficiency (PCE) by doping NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} into TiO{sub 2} cathode buffer layer. The dependence of devices performance on doping concentration of NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} is investigated. Results indicate that short-circuit current density (J{sub sc}) has an apparent improvement, leading to an enhancement of 22.7% in PCE for the optimized doping concentration of 0.05 mmol ml{sup −1} compared to the control devices. NaYF{sub 4}:Yb{sup 3+},Tm{sup 3+} nanoparticles (NPs) can play threefold roles, one is that the incident light in visible region can be scattered by NaYF{sub 4} NPs, the second is that solar irradiation in infrared region can be better utilized by Up-conversion effect of Yb{sup 3+} and Tm{sup 3+} ions, the third is that electron transport property in TiO{sub 2} thin film can be greatly improved.

  3. Wideband saturable absorption in few-layer molybdenum diselenide (MoSe₂) for Q-switching Yb-, Er- and Tm-doped fiber lasers.

    PubMed

    Woodward, R I; Howe, R C T; Runcorn, T H; Hu, G; Torrisi, F; Kelleher, E J R; Hasan, T

    2015-07-27

    We fabricate a free-standing molybdenum diselenide (MoSe2) saturable absorber by embedding liquid-phase exfoliated few-layer MoSe2 flakes into a polymer film. The MoSe2-polymer composite is used to Q-switch fiber lasers based on ytterbium (Yb), erbium (Er) and thulium (Tm) gain fiber, producing trains of microsecond-duration pulses with kilohertz repetition rates at 1060 nm, 1566 nm and 1924 nm, respectively. Such operating wavelengths correspond to sub-bandgap saturable absorption in MoSe2, which is explained in the context of edge-states, building upon studies of other semiconducting transition metal dichalcogenide (TMD)-based saturable absorbers. Our work adds few-layer MoSe2 to the growing catalog of TMDs with remarkable optical properties, which offer new opportunities for photonic devices. PMID:26367663

  4. Thermal evolution of the spin ordering at the concomitant spin-orbital rearrangement temperature in RVO3 (R=Lu, Yb and Tm)

    NASA Astrophysics Data System (ADS)

    Sarkar, Tapati; Ivanov, Sergey A.; Bazuev, G. V.; Nordblad, Per; Mathieu, Roland

    2016-07-01

    Synthesis, crystal structure and magnetization measurements of phase pure polycrystalline RVO3 (R=Lu, Yb and Tm) are reported. The compounds were stabilized in the orthorhombic structure by thermal treatment of the respective precursors (RVO4) in a reducing atmosphere. Special pressure treatment was carried out during the synthesis to ensure phase pure samples without secondary phases. Magnetization measurements reveal the presence of two spin ordering temperatures in the samples. Interestingly, at the lower spin ordering temperature, TSO2, the uncompensated excess moment of the antiferromagnetic spin structure has different field dependences above and below TSO2, causing a jump in the thermal evolution of the magnetization that changes sign with increasing field strength. This jump is associated with the reported magnetic and orbital rearrangement in the samples, and the different spin configurations in the C- and G-type antiferromagnetic structures.

  5. Double pulse laser deposition of polymer nanocomposite: NaYF4:Tm3+,Yb3+ films for optical sensors and light emitting applications

    NASA Astrophysics Data System (ADS)

    Darwish, Abdalla M.; Wilson, Simeon; Sarkisov, Sergey; Patel, Darayas

    2013-09-01

    The main objective of this paper is to demonstrate the feasibility of producing operationally Nanocomposite polymeric thin films for sensor and light emitting applications using the innovative modified double pulsed laser deposition (DPLD) technique. The existing PLD vacuum chamber was modified to accommodate multiple wavelength laser beams for in-situ-double-ablation/Deposition (DPLD) of multiple targets of host and dopants. Special design was made for cooling of the target to the threshold of the polymer ablation without interrupting the continuity of the ablation process. Multilayered of nanocomposites of acrylic polymers and nanoparticles of NaYF4:Tm3+ ,Yb3+ are fabricated using ultra-violet (UV) radiation (355 nm) ablating polymer targets and near-infra-red (near-IR) radiation (1064 nm) ablating inorganic targets. The films were characterized using the reflected high energy electron diffraction (RHEED), XRD , XRF, AFM, and FTIR absorption spectroscopy and tested as possible chemical sensors and light emitters.

  6. Real-time, non-invasive monitoring of hydrogel degradation using LiYF4:Yb(3+)/Tm(3+) NIR-to-NIR upconverting nanoparticles.

    PubMed

    Jalani, Ghulam; Naccache, Rafik; Rosenzweig, Derek H; Lerouge, Sophie; Haglund, Lisbet; Vetrone, Fiorenzo; Cerruti, Marta

    2015-07-14

    To design a biodegradable hydrogel as cell support, one should know its in vivo degradation rate. A technique commonly used to track gel degradation is fluorescence spectroscopy. However, the fluorescence from conventional fluorophores quickly decays, and the fluorophores are often moderately cytotoxic. Most importantly, they require ultraviolet or visible (UV-Vis) light as the excitation source, which cannot penetrate deeply through biological tissues. Lanthanide-doped upconverting nanoparticles (UCNPs) are exciting alternatives to conventional fluorophores because they can convert near-infrared (NIR) to UV-Vis-NIR light via a sequential multiphoton absorption process referred to as upconversion. NIR light can penetrate up to few cm inside tissues, thus making these UCNPs much better probes than conventional fluorophores for in vivo monitoring. Also, UCNPs have narrow emission bands, high photoluminescence (PL) signal-to-noise ratio, low cytotoxicity and good physical and chemical stability. Here, we show a nanocomposite system consisting of a biodegradable, in situ thermogelling injectable hydrogel made of chitosan and hyaluronic acid encapsulating silica-coated LiYF4:Yb(3+)/Tm(3+) UCNPs. We use these UCNPs as photoluminescent tags to monitor the gel degradation inside live, cultured intervertebral discs (IVDs) over a period of 3 weeks. PL spectroscopy and NIR imaging show that NIR-to-NIR upconversion of LiYF4:Yb(3+)/Tm(3+)@SiO2 UCNPs allows for tracking of the gel degradation in living tissues. Both in vitro and ex vivo release of UCNPs follow a similar trend during the first 5 days; after this time, ex vivo release becomes faster than in vitro, indicating a faster gel degradation ex vivo. Also, the amount of released UCNPs in vitro increases continuously up to 3 weeks, while it plateaus after 15 days inside the IVDs showing a homogenous distribution of UCNPs throughout the IVD tissue. This non-invasive optical method for real time, live tissue imaging holds

  7. Real-time, non-invasive monitoring of hydrogel degradation using LiYF4:Yb(3+)/Tm(3+) NIR-to-NIR upconverting nanoparticles.

    PubMed

    Jalani, Ghulam; Naccache, Rafik; Rosenzweig, Derek H; Lerouge, Sophie; Haglund, Lisbet; Vetrone, Fiorenzo; Cerruti, Marta

    2015-07-14

    To design a biodegradable hydrogel as cell support, one should know its in vivo degradation rate. A technique commonly used to track gel degradation is fluorescence spectroscopy. However, the fluorescence from conventional fluorophores quickly decays, and the fluorophores are often moderately cytotoxic. Most importantly, they require ultraviolet or visible (UV-Vis) light as the excitation source, which cannot penetrate deeply through biological tissues. Lanthanide-doped upconverting nanoparticles (UCNPs) are exciting alternatives to conventional fluorophores because they can convert near-infrared (NIR) to UV-Vis-NIR light via a sequential multiphoton absorption process referred to as upconversion. NIR light can penetrate up to few cm inside tissues, thus making these UCNPs much better probes than conventional fluorophores for in vivo monitoring. Also, UCNPs have narrow emission bands, high photoluminescence (PL) signal-to-noise ratio, low cytotoxicity and good physical and chemical stability. Here, we show a nanocomposite system consisting of a biodegradable, in situ thermogelling injectable hydrogel made of chitosan and hyaluronic acid encapsulating silica-coated LiYF4:Yb(3+)/Tm(3+) UCNPs. We use these UCNPs as photoluminescent tags to monitor the gel degradation inside live, cultured intervertebral discs (IVDs) over a period of 3 weeks. PL spectroscopy and NIR imaging show that NIR-to-NIR upconversion of LiYF4:Yb(3+)/Tm(3+)@SiO2 UCNPs allows for tracking of the gel degradation in living tissues. Both in vitro and ex vivo release of UCNPs follow a similar trend during the first 5 days; after this time, ex vivo release becomes faster than in vitro, indicating a faster gel degradation ex vivo. Also, the amount of released UCNPs in vitro increases continuously up to 3 weeks, while it plateaus after 15 days inside the IVDs showing a homogenous distribution of UCNPs throughout the IVD tissue. This non-invasive optical method for real time, live tissue imaging holds

  8. Impact of codopant ions on 2.5-3.0 μm emission of Er3+:4I11/2→4I13/2 transition in Yb,Er,Eu:LaYSGG crystal

    NASA Astrophysics Data System (ADS)

    Wang, Yan; Li, Jianfu; Zhu, Zhaojie; You, Zhenyu; Xu, Jinlong; Tu, Chaoyang

    2015-12-01

    The crystal of 1 at% Yb3+, 10 at% Er3+ and 0.1 at% Eu3+ triply doped La0.3Y2.7Sc2Ga3O12 (abbr. as Yb,Er,Eu:LaYSGG) was grown for the first time by using a Czochralski technique. Its absorption, near-infrared and mid-infrared fluorescence spectra, as well as the fluorescence decay curves of Er:4I13/2 and 4I11/2 levels were measured at room temperature. The spectroscopic properties including the absorption and emission cross-sections as well as the fluorescence lifetimes of the title crystal were revealed and compared with 10 at% Er3+:Y3Sc2Ga3O12 crystal. Spectral analyses show that the sensitization of Yb3+ ion leads to an enhanced 2.5-3.0 μm emission corresponding to Er3+:4I11/2→4I13/2 transition in the grown crystal, meanwhile, the depopulation of Eu3+ ion from Er3+ inhibits the self-termination effect successfully. The energy transfer mechanism was discussed; the energy transfer efficiencies of Yb3+→Er3+ (ET1) and Er3+→Eu3+ (ET2) were estimated to be 94.8% and 93.9%, respectively. The results indicates that Yb,Er,Eu:LaYSGG crystal is a good candidate for LD pumped mid-infrared laser.

  9. Blue and NIR emission from nanostructured Tm3+/  Yb3+ co-doped SiO2–Ta2O5 for photonic applications

    NASA Astrophysics Data System (ADS)

    Cardoso Muscelli, Wesley; de Oliveira Lima, Karmel; Thomaz Aquino, Felipe; Rocha Gonçalves, Rogéria

    2016-05-01

    This paper reports on the synthesis of Tm3+/Yb3+ co-doped SiO2–Ta2O5 nanocomposites prepared by a sol–gel route. XRD analysis revealed initial crystallization of the L-Ta2O5 structure dispersed in the silica host, which depended on lanthanide concentration. Vibrational spectroscopy showed low OH groups content, SiO2–Ta2O5 nanocomposite formation, and controlled phase separation characterized by the presence of Ta2O5 nanoparticles. Emission in the near infrared was evident and also depended on lanthanide concentration and excitation wavelength. Direct excitation on the host promoted NIR luminescence; higher intensity emerged at 980 nm, attributed to Yb3+ ions. Excitation of the Tm3+ excited levels elicited energy transfer between Tm3+ and Yb3+ ions. Excitation of the Tm3+ levels (visible range) and the host (UV) promoted emission in the S telecom band for all the samples. Excitation at 980 nm gave rise to upconversion emissions at 476 nm (blue) and 793 nm (NIR). At higher lanthanide concentration, the presence of a dominant cross-relaxation process reduced the blue emission with respect to the NIR emission. The color coordinates were similar to the coordinates of standard blue. All these luminescent properties make the synthesized materials potential candidates for photonic applications like energy converting devices, solar concentrators, and blue emitters.

  10. Synthesis, characterisation and properties of rare earth oxyselenides A4O4Se3 (A = Eu, Gd, Tb, Dy, Ho, Er, Yb and Y).

    PubMed

    Tuxworth, Andrew J; Wang, Chun-Hai; Evans, John S O

    2015-02-21

    Rare earth oxyselenides A4O4Se3 (A = Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb and Y) were synthesised using solid state reactions and three new structure types (β, γ, and δ) were observed. A4O4Se3 materials adopt either the α (A = Nd, Sm), β (A = Eu), γ (A = Gd, Tb) or δ (A = Dy, Ho, Er, Yb, Y) structure depending on the rare earth radius. Each structure type contains alternating [A2O2](2+) and Se(2-)/Se2(2-) layers. Different ordered and disordered arrangements of Se(2-) and [Se-Se](2-) give the Se layer flexibility and lead to the four different structure types observed. The volume coefficients of expansion for A4O4Se3 ranged from +1.746(9) × 10(-5) to +2.237(3) × 10(-5) K(-1) from 12 to 300 K; no structural phase transitions were observed in this temperature range. Diffuse reflection spectra show A4O4Se3 are semiconductors with band gap Eg 1.02-1.46 eV. Gd4O4Se3, Dy4O4Se3, and Tb4O4Se3 samples show antiferromagnetic ordering with Néel temperature, TN, of 7-9 K. DFT calculations confirm the two different valence states of Se(2-) and Se2(2-) in Eu4O4Se3. PMID:25581725

  11. Effects of water on Eu/sup 2 +/, Yb/sup 2 +/, and Es/sup 2 +/ cocrystallization in the Sr(Sm)SO/sub 4/-ethanol system

    SciTech Connect

    Mikheev, N.B.; Kamenskaya, A.N.; Kulyukhin, S.A.

    1988-11-01

    Measurements have been made on the effects of water on the cocrystallization of divalent europium, ytterbium, and einsteinium in the Sr(Sm)SO/sub 4/-ethanol system. Water levels from 3 to 6 M affect the Eu/sup 2 +/ and Yb/sup 2 +/ cocrystallization coefficients, while above 6 M, they do not alter. With divalent einsteinium, there are changes in the coefficient up to (H/sub 2/O) = 10 M. The effects of the water concentration on the solubility have been examined for the sulfates of these three elements.

  12. Enhancement of near-infrared to near-infrared upconversion emission in the CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opals.

    PubMed

    Wu, Hangjun; Yang, Zhengwen; Liao, Jiayan; Lai, Shenfeng; Qiu, Jianbei; Song, Zhiguo; Yang, Yong; Zhou, Dacheng

    2014-02-15

    In this Letter, CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opal with near-infrared to near-infrared upconversion emission was prepared by polystyrene colloidal crystal templates, and the influence of photonic bandgap on the upconversion emission was investigated. Comparing with the reference sample, suppression of the blue or red upconversion luminescence was observed in the inverse opals. It is interesting that the near-infrared upconversion emission located at about 803 nm was enhanced due to the inhibition of visible upconversion emission in the inverse opals. Additionally, the variety of upconversion emission mechanisms was observed and discussed in the CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opals. PMID:24562241

  13. Enhancement of near-infrared to near-infrared upconversion emission in the CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opals.

    PubMed

    Wu, Hangjun; Yang, Zhengwen; Liao, Jiayan; Lai, Shenfeng; Qiu, Jianbei; Song, Zhiguo; Yang, Yong; Zhou, Dacheng

    2014-02-15

    In this Letter, CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opal with near-infrared to near-infrared upconversion emission was prepared by polystyrene colloidal crystal templates, and the influence of photonic bandgap on the upconversion emission was investigated. Comparing with the reference sample, suppression of the blue or red upconversion luminescence was observed in the inverse opals. It is interesting that the near-infrared upconversion emission located at about 803 nm was enhanced due to the inhibition of visible upconversion emission in the inverse opals. Additionally, the variety of upconversion emission mechanisms was observed and discussed in the CeO₂: Er³⁺, Tm³⁺, Yb³⁺ inverse opals.

  14. Near-infrared photocatalysts of BiVO4/CaF2:Er3+, Tm3+, Yb3+ with enhanced upconversion properties

    NASA Astrophysics Data System (ADS)

    Huang, Shouqiang; Zhu, Nanwen; Lou, Ziyang; Gu, Lin; Miao, Chen; Yuan, Haiping; Shan, Aidang

    2014-01-01

    Upconversion photocatalysts have the potential to absorb the near-infrared (NIR) light in solar energy and improve the photocatalytic performance. A hierarchical upconversion photocatalyst of BiVO4 (BVO)/CaF2:Er3+, Tm3+, Yb3+ (CF) combined with the narrow-band semiconductor of BVO and the luminescence agent of CF to enhance upconversion properties was synthesized via the hydrothermal method. The CF particles were deposited homogeneously on the surface of the BVO/CF composite with regular dendritic structure, which led to efficient upconversion emissions. The upconversion emission intensity of the BVO/CF composite was 8 times higher than that of pure CF, through tailoring the crystal symmetry of lanthanide ions by Bi3+ ions. The upconverted ultraviolet (361 and 379 nm), violet (408 nm), and blue (485 nm) light was able to excite BVO for photocatalysis in BVO/CF under NIR irradiation, which improved the degradation rate of methyl orange (MO).Upconversion photocatalysts have the potential to absorb the near-infrared (NIR) light in solar energy and improve the photocatalytic performance. A hierarchical upconversion photocatalyst of BiVO4 (BVO)/CaF2:Er3+, Tm3+, Yb3+ (CF) combined with the narrow-band semiconductor of BVO and the luminescence agent of CF to enhance upconversion properties was synthesized via the hydrothermal method. The CF particles were deposited homogeneously on the surface of the BVO/CF composite with regular dendritic structure, which led to efficient upconversion emissions. The upconversion emission intensity of the BVO/CF composite was 8 times higher than that of pure CF, through tailoring the crystal symmetry of lanthanide ions by Bi3+ ions. The upconverted ultraviolet (361 and 379 nm), violet (408 nm), and blue (485 nm) light was able to excite BVO for photocatalysis in BVO/CF under NIR irradiation, which improved the degradation rate of methyl orange (MO). Electronic supplementary information (ESI) available: Additional tables and figures. See

  15. Photoluminescence of rare-earth ion (Eu3+, Tm3+, and Er3+)-doped and co-doped ZnNb2O6 for solar cells

    NASA Astrophysics Data System (ADS)

    Gao, Sen-Pei; Qian, Yan-Nan; Wang, Biao

    2015-08-01

    Visible converted emissions produced at an excitation of 286 nm in ZnNb2O6 ceramics doped with rare-earth ions (RE = Eu3+, Tm3+, Er3+ or a combination of these ions) were investigated with the aim of increasing the photovoltaic efficiency of solar cells. The structure of RE:ZnNb2O6 ceramics was confirmed by x-ray diffraction patterns. The undoped ZnNb2O6 could emit a blue emission under 286-nm excitation, which is attributed to the self-trapped excitons’ recombination of the efficient luminescence centers of edge-shared NbO6 groups. Upon 286-nm excitation, Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 ceramics showed blue, green, and red emissions, which correspond to the transitions of 5D0 → 7FJ (J = 1-4) (Eu3+), 1G4 → 3H6 (Tm3+), and 2H11/2/4S3/2 → 4I15/2 (Er3+), respectively. The calculated CIE chromaticity coordinates of Eu:ZnNb2O6, Tm:ZnNb2O6, and Er:ZnNb2O6 are (0.50, 0.31), (0.14, 0.19), and (0.29, 0.56), respectively. RE ion-co-doped ZnNb2O6 showed a combination of characteristic emissions. The chromaticity coordinates of Eu/Tm:ZnNb2O6, Eu/Er:ZnNb2O6, and Tm/Er:ZnNb2O6 were calculated to be (0.29, 0.24), (0.45, 0.37), and (0.17, 0.25). Project supported by the National Natural Science Foundation of China (Grant Nos. 10572155 and 10732100) and the Research Fund for the Doctoral Program of Ministry of Education, China (Grant No. 20130171130003).

  16. Structural and thermoelectric properties of BaRCo{sub 4}O{sub 7} (R = Dy, Ho, Er, Tm, Yb, and Lu)

    SciTech Connect

    Wong-Ng, W.; Yan, Y.; Liu, G.; Xie, W.; Tritt, T.; Kaduk, J.; Thomas, E.

    2011-12-01

    The structure and thermoelectric properties of a series of barium lanthanide cobaltites, BaRCo{sub 4}O{sub 7} (R = Dy, Ho, Er, Tm, Yb, and Lu), which were prepared using the spark plasma synthesis technique, have been investigated. The space group of these compounds was re-determined and confirmed to be P31c instead of the reported P6{sub 3}mc. The lattice parameters a and c range from 6.26279(2) Angst to 6.31181(6) Angst , and from 10.22468(6) Angst to 10.24446(15) Angst for R = Lu to Dy, respectively. The crystal structure of BaRCo{sub 4}O{sub 7} is built up from Kagome sheets of CoO{sub 4} tetrahedra, linked by triangular layers of CoO{sub 4} tetrahedra. The values of figure of merit (ZT) of the BaRCo{sub 4}O{sub 7} samples were determined to be around 0.02 at 800 K. X-ray diffraction patterns of these samples have been determined and submitted to the Powder Diffraction File.

  17. Measurement of Quantum Yield and Upconversion Brightness in Red, Blue and Green on NIR Excited M2O2S:Yb/Er/Ho/Tm Phosphors

    NASA Astrophysics Data System (ADS)

    Beeks, Ivan; Kumar, Ajith G.; Sardar, Dhiraj K.

    2015-03-01

    A series of broadly color tunable upconversion phosphors were synthesized from M2O2S (M=Y,Gd,La) using a flux fusion method. We investigate their upconversion properties as a function of the dopant concentrations and excitation power density. The phosphor compositions were determined for their upconversion characteristics under 800, 980 and 1550 nm excitations. By measuring the quantum yield and luminous brightness, we investigate their potential applications in biomedical imaging as well as NIR display applications. Results are compared with the well-known upconversion phosphor NaYF4:Yb/Er/Ho/Tm and found that the M2O2S phosphor systems are more efficient compared to NaYF4. By adopting various synthesis protocols, we were able to examine M2O2S in the size range of 10 nm to 10 μm. This research is supported by the National Science Foundation Partnerships for Research and Education in Materials (NSF-PREM) Grant N0-DMR-0934218.

  18. NIR to blue light upconversion in Tm{sup 3+}/Yb{sup 3+} codoped BaTiO{sub 3} tellurite glass

    SciTech Connect

    Kumari, Astha Rai, Vineet Kumar

    2015-05-15

    Upconversion is an interesting optical property, generally shown by rare-earth doped materials. This unusual optical behavior shown by these rare-earths doped materials are due to their peculiar atomic configuration and electronic transitions. Here, the Tm{sup 3+}-Yb{sup 3+} codoped BaTiO{sub 3} glass with TeO{sub 2} as former has been prepared by conventional melt and quench technique and the upconversion property has been investigated with the help of near infrared (NIR) to Visible UC study. The generation of the visible UC bands around ∼ 476 nm, ∼ 653 nm, ∼ 702 nm and one NIR UC band at ∼795 nm are assigned due to the {sup 1}G{sub 4}→ {sup 3}H{sub 6}, {sup 1}G{sub 4}→ {sup 3}F{sub 4}, {sup 3}F{sub 2}→ {sup 3}H{sub 6} and {sup 3}H{sub 4}→ {sup 3}H{sub 6} transitions respectively. The generations of these upconversion bands have been discussed in detail with the help of energy level diagram. The colour coordinates corresponding to the prepared material have been shown with the help of CIE chromaticity diagram. These glasses can be very appropriately used in the fabrication of solid state laser and as NIR to blue light upconverter.

  19. Ultraviolet-driven white light generation from oxyfluoride glass co-doped with Tm{sup 3+}-Tb{sup 3+}-Eu{sup 3+}

    SciTech Connect

    Kuznetsov, A. S.; Nikitin, A.; Tikhomirov, V. K.; Shestakov, M. V.; Moshchalkov, V. V.

    2013-04-22

    Tm{sup 3+}-Tb{sup 3+}-Eu{sup 3+} co-doped oxyfluoride glasses, doped with about 3.0 mol. % TmF{sub 3}, 0.25 mol. % TbF{sub 3}, and 0.25 mol. % EuF{sub 3}, have been prepared by melt quenching technique. Under excitation at commercial 365 nm, the rare-earth co-dopants are all directly excited and emit in the blue, green, and red, respectively, without appreciable energy transfer amongst the co-dopants. Tint of the white luminescence can be adjusted by changing the ratio of the co-dopants. Properties of the glass host promote excellent dissolution of the co-dopants and low non-radiative decay rate. The white emission at 365 nm excitation is suitable for light emitting diodes applications.

  20. Synthesis, Characterization, and Application of Core–Shell Co0.16Fe2.84O4@NaYF4(Yb, Er) and Fe3O4@NaYF4(Yb, Tm) Nanoparticle as Trimodal (MRI, PET/SPECT, and Optical) Imaging Agents

    PubMed Central

    2015-01-01

    Multimodal nanoparticulate materials are described, offering magnetic, radionuclide, and fluorescent imaging capabilities to exploit the complementary advantages of magnetic resonance imaging (MRI), positron emission tomography/single-photon emission commuted tomography (PET/SPECT), and optical imaging. They comprise Fe3O4@NaYF4 core/shell nanoparticles (NPs) with different cation dopants in the shell or core, including Co0.16Fe2.84O4@NaYF4(Yb, Er) and Fe3O4@NaYF4(Yb, Tm). These NPs are stabilized by bisphosphonate polyethylene glycol conjugates (BP-PEG), and then show a high transverse relaxivity (r2) up to 326 mM–1 s–1 at 3T, a high affinity to [18F]-fluoride or radiometal-bisphosphonate conjugates (e.g., 64Cu and 99mTc), and fluorescent emissions from 500 to 800 nm under excitation at 980 nm. The biodistribution of intravenously administered particles determined by PET/MR imaging suggests that negatively charged Co0.16Fe2.84O4@NaYF4(Yb, Er)-BP-PEG (10K) NPs cleared from the blood pool more slowly than positively charged NPs Fe3O4@NaYF4(Yb, Tm)-BP-PEG (2K). Preliminary results in sentinel lymph node imaging in mice indicate the advantages of multimodal imaging. PMID:26172432

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

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

  2. Controllable chrominance and highly improved luminescent quantum yield of YV(1-x)P(x)O4: Tm, Dy, Eu inverse opal white light phosphors.

    PubMed

    Zhou, Pingwei; Zhu, Yongsheng; Xu, Wen; Xu, Lin; Song, Hongwei

    2013-11-01

    In this work, rare earth (RE) ions tri-doped YV(1-x)P(x)O(4): RE(3+) (RE = Tm, Dy, Eu) inverse opal photonic crystals (IOPCs) were fabricated by the PMMA template method, which demonstrated efficient white light emissions under ultraviolet excitation. It is significant to observe that the chrominance of the white light could be largely modulated by the photonic stop band of the IOPCs. And more, the photoluminescence quantum yield in the IOPCs was largely improved over the grinded reference (REF) because the undesired energy transfer (ET) process was effectively restrained. PMID:24216800

  3. Photoluminescence properties of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) activated NaInW{sub 2}O{sub 8} wolframite host lattice

    SciTech Connect

    Asiri Naidu, S.; Boudin, S.; Varadaraju, U.V.; Raveau, B.

    2012-01-15

    The photoluminescence (PL) studies on NaIn{sub 1-x}RE{sub x}W{sub 2}O{sub 8}, with RE=Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+} phases have shown that the relative contribution of the host lattice and of the intra-f-f emission of the activators to the PL varies with the nature of the rare earth cation. In the case of Dy{sup 3+} and Tm{sup 3+} activators, with yellow and blue emission, respectively, the energy transfer from host to the activator plays a major role. In contrast for Eu{sup 3+}, with intense red emission, the host absorption is less pronounced and the intra-f-f transitions of the Eu{sup 3+} ions play a major role, whereas for Tb{sup 3+} intra-f-f transitions are only observed, giving rise to green emission. - Graphical abstract: NaInW{sub 2}O{sub 8} double tungstate doped with Eu{sup 3+}, Dy{sup 3+}, Tb{sup 3+}and Tm{sup 3+} shows characteristic emission of intense red for Eu{sup 3+}, yellow for Dy{sup 3+}, green for Tb{sup 3+} and blue for Tm{sup 3+}. Highlights: Black-Right-Pointing-Pointer Characteristic emissions of rare earths (Eu{sup 3+}, Tb{sup 3+}, Dy{sup 3+} and Tm{sup 3+}) are observed NaInW{sub 2}O{sub 8} wolframite. Black-Right-Pointing-Pointer Energy transfer from host to the activators (Eu{sup 3+} Dy{sup 3+} Tm{sup 3+} is observed. Black-Right-Pointing-Pointer PL properties of rare earth ions depend on minor structural variations in the host lattice.

  4. Lattice dynamics of rare-earth titanates with the structure of pyrochlore R 2Ti2O7 ( R = Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu): Ab initio calculation

    NASA Astrophysics Data System (ADS)

    Chernyshev, V. A.; Petrov, V. P.; Nikiforov, A. E.

    2015-05-01

    The ab initio calculation has been performed for the crystal structure and the phonon spectrum of titanates with the structure of pyrochlore R 2Ti2O7 ( R = Gd-Lu). The frequencies and types of fundamental vibrations have been found. For R = Tb, Tm, and Yb, this calculation has been carried out for the first time; furthermore, there is no available information on experimental studies of the phonon spectrum for Tm and Yb. The influence of hydrostatic pressure to 35 GPa on the structure, dynamics, and elastic properties of the Gd2Ti2O7 lattice has been investigated. The dependence of the phonon frequencies on the pressure has been obtained. The calculations have predicted that the relative change in the pyrochlore structure volume during compression at pressures to 35 GPa is well described by the third-order Birch-Murnaghan equation of states. The results of the calculations agree with the available experimental data. It has been shown that the structural, dynamic, and elastic properties of the R 2Ti2O7 crystal lattice can be adequately described in the case where the inner shells of the RE ion up to 4 f are replaced by the pseudopotential.

  5. EPR study of the ground state of Mn2+ impurity ions in alumoborates MAl3(BO3)4 (M = Y, Eu, Tm)

    NASA Astrophysics Data System (ADS)

    Prokhorov, А А; Prokhorov, A. D.; Chernush, L. F.; Dyakonov, V. P.; Szymczak, H.; Dejneka, A.

    2015-06-01

    New data about the ground state of the Mn2+ impurity ions in a series of single crystals of alumbrados MAl3(BO3)4, where M = Y,Eu,Tm were obtained. The electron paramagnetic resonance (EPR) spectra of the Mn2+ spectra were studied, the parameters of the spin Hamiltonian describing the angular dependence of the spectrum were defined. It was shown that Mn2+ ions substitute trivalent ions of rare earth metals without changing the symmetry of the substitution site. The charge compensation process was found to be a nonlocal one. The cooling of the crystals leads to the increase of the splitting of the ground state, which is associated with the anisotropy of the thermal expansion coefficient. It was shown that an application of the superposition model to explain the distortions induced by an impurity Mn2+ ion has some limitations. The EPR linewidth of the Mn2+ ion in the TmAl3(BO3)4 crystal increases with increasing temperature as a result of the dipole-dipole and exchange interactions with the excited states of the host lattice Tm3+ ion.

  6. Crystal Structures and Reference Powder Patterns of BaR2ZnO5 (R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, and Tm)

    PubMed Central

    Kaduk, J. A.; Wong-Ng, W.; Greenwood, W.; Dillingham, J.; Toby, B. H.

    1999-01-01

    Reference x-ray powder patterns and the crystal structures of the lanthanide compounds, BaR2ZnO5, in which R = La, Nd, Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm, were determined by the x-ray Rietveld refinement technique. A structural trend was confirmed for this series of compounds. The compounds with smaller ionic radii (R = Sm, Eu, Gd, Dy, Ho, Y, Er, or Tm) are isostructural to the orthorhombic “green phase” (BaY2CuO5). The lattice parameters for compounds with R = Tm to Sm range from a = 7.01855(9) Å to 7.20452(14) Å, b = 12.25445 (17) Å to 12.5882(2) Å, and c = 5.6786(14) Å to 5.81218(11) Å, respectively. R is sevenfold coordinated inside a monocapped trigonal prism. These prisms share edges to form wave-like chains parallel to the long b-axis. The BaR2ZnO5 compounds which contain larger size R (La and Nd) crystallize in the tetragonal space group I4/mcm. The lattice parameters are a = 6.90982(10) and c = 11.5977(2) Å for BaLa2ZnO5, and a = 6.75979(5) Å and c = 11.54560(12) Å for BaNd2ZnO5. The structure consists of ZnO4 tetrahedra (instead of planar CuO4 groups as found in BaR2CuO5) with 10-fold coordinated bicapped square prismatic Ba and 8-fold coordinated bicapped trigonal prismatic R ions between them. The reference x-ray powder patterns will be submitted to the Powder Diffraction File (PDF).

  7. NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}, Er{sup 3+}/Yb{sup 3+}) microspheres: the synthesis and optical properties

    SciTech Connect

    Gao, Zhiyi; Wang, Zhiying; Fu, Linlin; Yang, Xingxing; Fu, Zuoling; Wu, Zhijian; Jeong, Jung Hyun

    2015-10-15

    The strong green upconversion (UC) emission were observed in various Er{sup 3+}, Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples synthesized via a hydrothermal route. The UC intensity depends on the dopant concentration, and the optimal UC emission was obtained in NaLa(MoO{sub 4}){sub 2}: 0.02Er{sup 3+}/0.10 Yb{sup 3+}. - Highlights: • The NaLa(MoO{sub 4}){sub 2} microspheres doped with Eu{sup 3+}, Sm{sup 3+} and Er{sup 3+}/Yb{sup 3+} were synthesized by a hydrothermal method. • The effects of the EDTA in the initial solution crystal phase and morphology were studied. • The down-conversion luminescence properties of NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}) were investigated. • The UC luminescence properties and mechanism of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} was discussed. - Abstract: NaLa(MoO{sub 4}){sub 2}: RE{sup 3+} (RE{sup 3+} = Eu{sup 3+}, Sm{sup 3+}) microspheres have been synthesized at 180 °C via a facile EDTA-mediated hydrothermal route. X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), photoluminescence (PL) spectra were employed to characterize the samples. It was found that the amount of EDTA in the initial solution was responsible for crystal phase and shape determination. The effect of Eu{sup 3+} and Sm{sup 3+} doping concentrations on the luminescent intensity was also investigated in details. Furthermore, the up-conversion (UC) emissions have been observed in a series of Er{sup 3+}/Yb{sup 3+} co-doped NaLa(MoO{sub 4}){sub 2} samples. Concentration dependent studies revealed that the optimal composition was realized for a 2% Er{sup 3+} and 10% Yb{sup 3+}-doping concentration.

  8. Observation of superconductivity at 30~46 K in A(x)Fe₂Se₂(A = Li, Na, Ba, Sr, Ca, Yb, and Eu).

    PubMed

    Ying, T P; Chen, X L; Wang, G; Jin, S F; Zhou, T T; Lai, X F; Zhang, H; Wang, W Y

    2012-01-01

    New iron selenide superconductors by intercalating smaller-sized alkali metals (Li, Na) and alkaline earths using high-temperature routes have been pursued ever since the discovery of superconductivity at about 30 K in KFe₂Se₂, but all have failed so far. Here we demonstrate that a series of superconductors with enhanced T(c) = 30∼46 K can be obtained by intercalating metals, Li, Na, Ba, Sr, Ca, Yb, and Eu in between FeSe layers by the ammonothermal method at room temperature. Analysis on their powder X-ray diffraction patterns reveals that all the main phases can be indexed based on body-centered tetragonal lattices with a∼3.755-3.831 Å while c∼15.99-20.54 Å. Resistivities show the corresponding sharp transitions at 45 K and 39 K for NaFe₂Se₂ and Ba₀.₈Fe₂Se₂, respectively, confirming their bulk superconductivity. These findings provide a new starting point for studying the properties of these superconductors and an effective synthetic route for the exploration of new superconductors as well. PMID:22645642

  9. Crystal structures of RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) studied by single crystal X-ray diffraction

    SciTech Connect

    Gribanov, Alexander; Grytsiv, Andriy; Rogl, Peter; Seropegin, Yurii; Giester, Gerald

    2009-07-15

    The crystal structures of ternary compounds RPt{sub 3-x}Si{sub 1-y}(R=Y, Tb, Dy, Ho, Er, Tm, Yb) have been elucidated from X-ray single crystal CCD data. All compounds are isotypic and crystallize in the tetragonal space group P4/mbm. The general formula RPt{sub 3-x}Si{sub 1-y} arises from defects: x{approx}0.20, y{approx}0.14. The crystal structure of RPt{sub 3-x}Si{sub 1-y} can be considered as a packing of four types of building blocks which derive from the CePt{sub 3}B-type unit cell by various degrees of distortion and Pt, Si-defects. - Graphical Abstract: Electron density in RPt{sub 3-x}Si{sub 1-y} at 0, 1/2 , 0.

  10. Doxorubicin-loaded NaYF4:Yb/Tm-TiO2 inorganic photosensitizers for NIR-triggered photodynamic therapy and enhanced chemotherapy in drug-resistant breast cancers.

    PubMed

    Zeng, Leyong; Pan, Yuanwei; Tian, Ying; Wang, Xin; Ren, Wenzhi; Wang, Shouju; Lu, Guangming; Wu, Aiguo

    2015-07-01

    The combination therapy has exhibited important potential for the treatment of cancers, especially for drug-resistant cancers. In this report, bi-functional nanoprobes based on doxorubicin (DOX)-loaded NaYF4:Yb/Tm-TiO2 inorganic photosensitizers (FA-NPs-DOX) were synthesized for in vivo near infrared (NIR)-triggered inorganic photodynamic therapy (PDT) and enhanced chemotherapy to overcome the multidrug resistance (MDR) in breast cancers. Using the up-conversion luminescence (UCL) performance of NaYF4:Yb/Tm converting near-infrared (NIR) into ultraviolent (UV) lights, reactive oxygen species (ROS) were triggered from TiO2 inorganic photosensitizers for PDT under the irradiation of a 980 nm laser, by which the deep-penetration and low photo-damage could be reached. Moreover, nanocarrier delivery and folic acid (FA) targeting promoted the cellular uptake, and accelerated the release of DOX in drug-sensitive MCF-7 and resistant MCF-7/ADR cells. The toxicity assessment in vitro and in vivo revealed the good biocompatibility of the as-prepared FA-NPs-DOX nanocomposites. By the combination of enhanced chemotherapy and NIR-triggered inorganic PDT, the viability of MCF-7/ADR cells could decrease by 53.5%, and the inhibition rate of MCF-7/ADR tumors could increase up to 90.33%, compared with free DOX. Therefore, the MDR of breast cancers could be obviously overcome by enhanced chemotherapy and NIR-triggered inorganic PDT of FA-NPs-DOX nanocomposites under the excitation of a 980 nm laser.

  11. High-throughput and microwave investigation of rare earth phosphonatoethanesulfonates-Ln(O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}) (Ln=Ho, Er, Tm, Yb, Lu, Y)

    SciTech Connect

    Sonnauer, Andreas

    2008-11-15

    Following the strategy of using bifunctional phosphonic acids for the synthesis of new metal phosphonates, the flexible ligand 2-phosphonoethanesulfonic acid, H{sub 2}O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}H (H{sub 3}L), was used in a high-throughput (HT) and microwave investigation of rare earth phosphonatoethanesulfonates. The HT-investigation led to six isotypic compounds Ln(O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}) with Ln=Ho (1), Er (2), Tm (3), Yb (4), Lu (5) and Y (6). The syntheses were scaled-up in glass reactor tubes in order to obtain larger amounts for a detailed characterization. Based on these results all compounds could be also synthesized by microwave-assisted heating and the influence of reaction time and stirring rate during the synthesis was established. For compound 2 the crystal structure was determined by single-crystal X-ray diffraction. The compounds contain isolated slightly distorted LnO{sub 6} octahedra that are connected by the phosphonate and sulfonate groups into a three-dimensional framework. Thermogravimetric investigations demonstrate the high thermal stability of the compounds up to 460 deg. C. - Graphical abstract: A high-throughput and microwave investigation of the System LnX{sub 3}/H{sub 2}O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}/NaOH/H{sub 2}O led to six new compounds Ln(O{sub 3}P-C{sub 2}H{sub 4}-SO{sub 3}) with Ln=Ho, Er, Tm, Yb, Lu, Y.

  12. New high pressure rare earth tantalates RE{sub x}Ta{sub 2}O{sub 5+1.5x} (RE=La, Eu, Yb)

    SciTech Connect

    Zibrov, Igor P.; Filonenko, Vladimir P.; Zakharov, Nikolai D.; Nikishina, Elena E.; Lebedeva, Elena N.

    2013-07-15

    Rare earth tantalates La{sub 0.075}Ta{sub 2}O{sub 5.113}, Eu{sub 0.089}Ta{sub 2}O{sub 5.134} and Yb{sub 0.051}Ta{sub 2}O{sub 5.077} have been prepared by solid state reaction at P=7.0 GPa and T=1050–1100 °C and studied by X-ray diffraction, thermal analysis and electron microscopy. Low hydrated amorphous tantalum, lanthanum, europium and ytterbium hydroxides were used as starting materials. Aqueous as well as anhydrous compounds were obtained. Title tantalates are crystallized in the structure type of F–Ta{sub 2}O{sub 5} [Zibrov et al. Russ. J. Inorg. Chem. 48 (2003) 464–471] [5]. The structure was refined by the Rietveld method from X-ray powder diffractometer data: La{sub 0.075}Ta{sub 2}O{sub 5.113}, a=10.5099(2), b=7.2679(1), c=6.9765(1) Å, V=532.90(1) Å{sup 3}, Z=6, space group Ibam; Eu{sub 0.089}Ta{sub 2}O{sub 5.134}, a=10.4182(3), b=7.2685(1), c=6.9832(1) Å, V=528.80(2) Å{sup 3}, Z=6, space group Ibam; Yb{sub 0.051}Ta{sub 2}O{sub 5.077}, a=10.4557(2), b=7.3853(1), c=6.8923(1) Å, V=532.21(1) Å{sup 3}, Z=6, space group Ibam. RE atoms do not replace the tantalum in its positions but the only water in the channels of the structure. Highly charged cations RE{sup +3} compress the unit cell so that its volume becomes less than that of F–Ta{sub 2}O{sub 5}. Significant decrease of the unit cell volume after water removal from the structure is possible due to the puckering of pentagonal bipyramid layers and change of the corrugation angle in the layer. - Graphical abstract: The structure of RE{sub x}Ta{sub 2}O{sub 5+1.5x} and its HRTEM image (“A” arrows show empty channel, “B” arrows show filled channel). - Highlights: • We synthesized new tantalates of RE under high pressure high temperature conditions. • RE atoms replace water molecules in the channels of the structure. • Aqueous as well as anhydrous tantalates were obtained. • Highly charged cations RE{sup +3} compress the unit cell decreasing RE–O distances.

  13. NaYF4:Yb,Tm nanocrystals and TiO2 inverse opal composite films: a novel device for upconversion enhancement and solid-based sensing of avidin.

    PubMed

    Xu, Sai; Xu, Wen; Wang, Yunfeng; Zhang, Shuang; Zhu, Yongsheng; Tao, Li; Xia, Lei; Zhou, Pingwei; Song, Hongwei

    2014-06-01

    Upconversion luminescence (UCL) detection based on rare-earth doped upconversion nanocrystals (UCNCs) as probes has been proved to exhibit a large anti-Stokes shift, no autofluorescence from biological samples, and no photobleaching. However, it is still a challenge to achieve a stable, reproducible solid-based UCL biosensor because of ineffective UCL of the UCNCs. In this work, we fabricated TiO2 inverse opal photonic crystals (IOPCs)/NaYF4:Yb(3+),Tm(3+) (Er(3+)) UCNC composite films, which can tremendously improve the overall UCL of Tm(3+) as high as 43-fold. Based on the fluorescence resonance energy transfer (FRET) and the specific interaction between biotin and avidin, a novel solid-based UC biosensor is presented for sensing avidin. This solid-based detection system is convenient for detection, and also can offer two parameters for detecting trace amounts of avidin, namely, the emission intensity and the fluorescence decay time. The sensor has a high sensitivity of 34 pmol(-1), a good linear relationship of 0.996 and a low detection limit of 48 pmol. It also exhibits excellent long-time photostability, and the absence of autofluorescence, and thus may have great potential for versatile applications in biodetection. PMID:24752220

  14. Ag{sub 2}O dependent up-conversion luminescence properties in Tm{sup 3+}/Er{sup 3+}/Yb{sup 3+} co-doped oxyfluorogermanate glasses

    SciTech Connect

    Hu, Yuebo; Qiu, Jianbei Song, Zhiguo; Zhou, Dacheng

    2014-02-28

    Up-conversion (UC) luminescence properties of Ag/Tm{sup 3+}/Er{sup 3+}/Yb{sup 3+} co-doped oxyfluorogermanate glasses have been studied to assess the effective role of silver nanoparticles as a sensitizer for Tm{sup 3+} and Er{sup 3+} ions. The X-ray diffraction patterns obtained in this work do not reveal any crystalline phase in the glass. However, the absorption spectra reveal that surface plasmons resonance band of Ag undergoes a distinct split with two maxima and a very broad absorption peak with a background that extends toward the near infrared (NIR) with the increasing of Ag{sub 2}O added concentration. Transmission electron microscope images confirm that silver nanoparticles have been precipitated from matrix glasses and show their distribution, size, and shapes. In addition, changes in UC luminescence intensity of four emission bands 476, 524, 546, and 658 nm corresponding to {sup 1}G{sub 4} → {sup 3}H{sub 6} (Tm{sup 3+}), ({sup 2}H{sub 11/2}, {sup 4}S{sub 3/2}) → {sup 4}I{sub 15/2} (Er{sup 3+}), and {sup 4}F{sub 9/2} → {sup 4}I{sub 15/2} (Er{sup 3+}) transitions, respectively, as a function of silver addition to the base composition have been measured under 980 nm excitation. It is confirmed that Ag{sub 2}O added concentration plays an important role in increasing the UC luminescence intensity; however, further increase in Ag{sub 2}O added concentration reduces the intensity.

  15. Up/down conversion luminescence and charge compensation investigation of Ca0.5Y1-x(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors

    NASA Astrophysics Data System (ADS)

    Mahalingam, Venkatakrishnan; Thirumalai, Jagannathan; Krishnan, Rajagopalan; Mantha, Srinivas

    2016-01-01

    Microstructures of Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors were prepared via the solid-state reaction method. X-ray diffraction, scanning electron microscopy and photoluminescence were used to characterize the prepared phosphor samples. The results reveal that the phosphor samples have single phase scheelite structures with tetragonal symmetry of I41/a. The down/up conversion photoluminescence of the Ca0.5Y(1-x)(WO4)2:xLn3+ (Ln = Pr, Sm, Eu, Tb, Dy, Yb/Er) phosphors properties reveal characteristic visible emissions. The energy transfer process, fluorescence lifetime and color coordinates are discussed in detail. Furthermore, the phosphor Ca0.5Y(1-x)(WO4)2:xPr3+ co-doped with alkali chlorides shows the enhancement of luminescence, which was found in the sodium chloride co-doped powder phosphor. The photometric characteristics indicate the suitability of the inorganic powder phosphors for solid-state lighting and display applications.

  16. Synthetic and spectroscopic studies of vanadate glaserites II: Photoluminescence studies of Ln:K{sub 3}Y(VO{sub 4}){sub 2} (Ln=Eu, Er, Sm, Ho, or Tm)

    SciTech Connect

    Kimani, Martin M. McMillen, Colin D. Kolis, Joseph W.

    2015-03-15

    Glaserite-type potassium yttrium double vanadates (K{sub 3}Y(VO{sub 4}){sub 2}) doped with Eu{sup 3+}, Er{sup 3+}, Sm{sup 3+}, Ho{sup 3+}, or Tm{sup 3+} have been synthesized by solid state reactions at 1000 °C for 48 h and their photoluminescence properties investigated. Efficient energy transfer from the vanadate group to the rare earth ion has been established by photoluminescence investigation. Ultraviolet excitation into the metal to ligand charge transfer band of the vanadate groups results in orange-red, blue and green emissions from Eu{sup 3+} (592 nm), Sm{sup 3+} (602 nm), Tm{sup 3+} (475 nm), Er{sup 3+} (553 nm), and Ho{sup 3+} (541–551 nm) dopant ions. The emission intensities of the lanthanide-doped K{sub 3}Y(VO{sub 4}){sub 2} powders were studied as a function of dopant ion concentrations. Over the concentration ranges studied, no emission quenching was observed for Eu{sup 3+} or Ho{sup 3+} dopants, while Er{sup 3+}, Sm{sup 3+} and Tm{sup 3+} dopants did exhibit such effects for dopant ion concentrations greater than 5%, probably due to cross relaxation processes. - Graphical abstract: Synthesis and photoluminescence in vanadate glaserites. - Highlights: • K{sub 3}Y(VO{sub 4}){sub 2} doped with Eu, Er, Tm, Sm, or Ho were synthesized via solid-state reactions. • Photoluminescence properties are investigated. • The lanthanide doped K{sub 3}Y(VO{sub 4}){sub 2} compounds revealed efficient energy transfer from the vanadate group to the rare earth ions. • The presented compounds are promising materials for light display systems, lasers, and optoelectronic devices.

  17. Correlation between slow magnetic relaxation and the coordination structures of a family of linear trinuclear Zn(II)-Ln(III)-Zn(II) complexes (Ln = Tb, Dy, Ho, Er, Tm and Yb).

    PubMed

    Maeda, Moe; Hino, Shiori; Yamashita, Kei; Kataoka, Yumiko; Nakano, Motohiro; Yamamura, Tomoo; Kajiwara, Takashi

    2012-11-28

    Six linear trinuclear [Ln{Zn(L)(AcO)}(2)]BPh(4) complexes (H(2)L denotes the Schiff-base ligand formed by a condensation reaction between ethylenediamine and two equivalents of o-vanillin), including Ln = Tb (1), Dy (2), Ho (3), Er (4), Tm (5) and Yb (6) were synthesized and were confirmed to be isostructural via X-ray crystallographic analyses. The Ln(III) ion in each complex is deca-coordinated by four equatorial oxygen donors from the methoxo groups of the Schiff-base ligands, two oxygen donors from the acetate anions and four axial oxygen donors from the phenoxo groups of the Schiff-base ligands. AC susceptibility measurements, with an oscillating frequency of 10 to 10,000 Hz, revealed that 1, 2, 4 and 6 show slow magnetic relaxation under a 1000 Oe DC bias field, which occurs via a single process, as confirmed by the semi-circular Cole-Cole plots. These complexes are considered to be field-induced single-molecule magnets under these conditions. The presence or absence of the slow magnetic relaxation process is discussed by correlating the characteristic magnetic anisotropy of each Ln(III) ion with the ligand field anisotropy.

  18. Structure determination of KScS₂, RbScS₂ and KLnS₂ (Ln = Nd, Sm, Tb, Dy, Ho, Er, Tm and Yb) and crystal-chemical discussion.

    PubMed

    Havlák, Lubomír; Fábry, Jan; Henriques, Margarida; Dušek, Michal

    2015-07-01

    The title structures of KScS2 (potassium scandium sulfide), RbScS2 (rubidium scandium sulfide) and KLnS2 [Ln = Nd (potassium neodymium sufide), Sm (potassium samarium sulfide), Tb (potassium terbium sulfide), Dy (potassium dysprosium sulfide), Ho (potassium holmium sulfide), Er (potassium erbium sulfide), Tm (potassium thulium sulfide) and Yb (potassium ytterbium sulfide)] are either newly determined (KScS2, RbScS2 and KTbS2) or redetermined. All of them belong to the α-NaFeO2 structure type in agreement with the ratio of the ionic radii r(3+)/r(+). KScS2, the member of this structural family with the smallest trivalent cation, is an extreme representative of these structures with rare earth trivalent cations. The title structures are compared with isostructural alkali rare earth sulfides in plots showing the dependence of several relevant parameters on the trivalent cation crystal radius; the parameters thus compared are c, a and c/a, the thicknesses of the S-S layers which contain the respective constituent cations, the sulfur fractional coordinates z(S(2-)) and the bond-valence sums. PMID:26146403

  19. Enhanced dual contrast agent, Co(2+)-doped NaYF4:Yb(3+),Tm(3+) nanorods, for near infrared-to-near infrared upconversion luminescence and magnetic resonance imaging.

    PubMed

    Xia, Ao; Zhang, Xiaofeng; Zhang, Jun; Deng, Yunyun; Chen, Qiang; Wu, Shishan; Huang, Xiaohua; Shen, Jian

    2014-11-01

    Dual-modality imaging with magnetic resonance (MR) and upconversion luminescence (UCL) is a promising technique for molecular imaging in biomedical research. Multifunctional lanthanide-based nanoparticles have been widely investigated as agents for contrast enhanced MR and fluorescence imaging. However, the use of rare earth fluoride nanoparticles for dual-modality imaging of T2-weighted MR and UCL is rarely reported. We find that NaYF4:Yb(3+),Tm(3+),Co(2+) (MUC) nanorods can be applied as a high-performance dual contrast agent for both T2-weighted MR and UCL dual-modality imaging. After modification with 6-O-carboxymethyl chitosan (OCC), MUC nanorods can be endocytosed by cells without showing signs of cytotoxicity. High-quality UCL images of living cells incubated with MUC-OCC nanorods were acquired on a near-infrared (NIR) confocal microscopy under the excitation at 980 nm. Moreover, MUC-OCC nanorods display high transverse (r2) relaxivities in vitro. The application of low-dose MUC-OCC nanorods for NIR-to-NIR UCL and MR dual-modality in vivo imaging was also carried out successfully. In addition, the toxicity of MUC-OCC nanorods was evaluated by MTT assay, serological tests and histological analysis of visceral organs.

  20. Large electric polarization in high pressure synthesized orthorhombic manganites RMnO3 (R=Ho,Tm,Yb and Lu) by using the double-wave PE loop measurements

    NASA Astrophysics Data System (ADS)

    Chai, Y. S.; Oh, Y. S.; Manivannan, N.; Yang, Y. S.; Kim, Kee Hoon; Feng, S. M.; Wang, L. J.; Jin, C. Q.

    2009-03-01

    The magnitude of electric polarization via the conventional pyroelectric current and/or PE loop measurements often is ambiguous due to resistive components of the sample. To avoid this, a new technique called the double-wave method has been recently developed [1], in which only hysteretic PE components can be measured. Using this technique, we have measured the ferroelectric polarization of the orthorhombic RMnO3 (R=Ho, Tm, Yb, and Lu) synthesized under high pressure. Large remnant polarization Pr up to 920 μC/m^2 is observed at 10 K for LuMnO3. Furthermore, the Pr vs. temperature data from the PE loop has shown consistency with that measured through the pyroelectric current measurements, supporting a theoretical prediction of large polarization in the E-type spin structure in this system [2]. We also discuss the influence of thermal histories on the ferroelectric domain dynamics and possible internal bias field effects originating from oxygen vacancies in RMnO3. [1] M. Fukunaga, et al. J. Phys. Soc. Jpn. 77, 064706 (2008). [2] I. A. Sergienko, et al. Phys. Rev. Lett., 97, 227204 (2006)

  1. Anomalous Hall Effect in Three Ferromagnets: EuFe4Sb12, Yb14MnSb11, and Eu8Ga16Ge30

    SciTech Connect

    Sales, Brian C; Jin, Rongying; Mandrus, David; Khalifah, Peter

    2006-01-01

    The Hall resistivity ({rho}{sub xy}), resistivity ({rho}{sub xx}), and magnetization of three metallic ferromagnets are investigated as a function of magnetic field and temperature. The three ferromagnets, EuFe{sub 4}Sb{sub 12} (T{sub c}{approx}84 K), Yb{sub 14}MnSb{sub 11} (T{sub c}{approx}53 K), and Eu{sub 8}Ga{sub 16}Ge{sub 30} (T{sub c}{approx}36 K) are Zintl compounds with carrier concentrations between 1 x 10{sup 21} and 3.5 x 10{sup 21} cm{sup -3}. The relative decrease in {rho}{sub xx} below T{sub c} [{rho}{sub xx}(T{sub c})Y{rho}{sub xx}(2 K)] is 28, 6.5, and 1.3 for EuFe{sub 4}Sb{sub 12}, Yb{sub 14}MnSb{sub 11}, and Eu{sub 8}Ga{sub 16}Ge{sub 30}, respectively. The low carrier concentrations coupled with low magnetic anisotropies allow a relatively clean separation between the anomalous ({rho}{sub xy}), and normal contributions to the measured Hall resistivity. For each compound the anomalous contribution in the zero field limit is fit to a{rho}{sub xx}+{sigma}{sub xy}{rho}{sub xx}{sup 2} for temperatures TEuFe{sub 4}Sb{sub 12}, Yb{sub 14}MnSb{sub 11}, and Eu{sub 8}Ga{sub 16}Ge{sub 30}, respectively, and is independent of temperature for T

  2. The high-pressure synthesis and characterization of some praseodymium-substituted rare-earth-based R{sub 2}Ba{sub 4}Cu{sub 7}O{sub 14-{delta}} (R = Nd, Eu, Tm)

    SciTech Connect

    Teng-Ming Chen; Kao, F.S.

    1997-08-01

    The formation of phases in the (R{sub 1-x}Pr{sub x}){sub 2}Ba{sub 4}Cu{sub 7}O{sub 14+{delta}} (Pr-doped R247; R = Nd, Eu, Tm) system with x = 0-1.0 was investigated. Samples of the title series were synthesized at 980-990{degree}C at 25 bar O{sub 2}, followed by annealing at 300{degree}C under 130 bar O{sub 2} for 30 hr. Oxygen content of the samples has been determined by iodometric titration. Single-phased samples has been determined by iodometric titration. Single-phased samples were obtained with x smaller than or equal to 0.3, 0.4, and 0.4 for R = Nd, Eu, and Tm, respectively, as indicated by X-ray diffraction measurements. With increasing amount of Pr substituting for R, the cell dimensions of the Pr-doped R247 phases were found to expand steadily, whereas the corresponding structural orthorhombicity was observed to decrease systematically. Superconducting transition temperatures (T{sub c}`s) of the title phases were found to be significantly suppressed upon Pr doping, as indicated by field-cooled temperature-dependent magnetization studies. The effect of Pr substitution on T{sub c}`s of R247 (R = Y, Eu, Er, Tm, Nd, Dy) phases was investigated and compared as a function of R{sup 3+} radii, but no size dependence effect was observed. In addition, field-dependent magnetization studies for a series of (Eu{sub 1-x}Pr{sub x}){sub 2}Ba{sub 4}Cu{sub 7}O{sub 14+{delta}} samples with x = 0, 0.2, and 0.4, respectively, are also reported.

  3. Preparation and spectroscopic properties of rare-earth (RE) (RE = Sm, Eu, Tb, Dy, Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) phosphate in vacuum ultraviolet region

    SciTech Connect

    Zhang, Zhi-Jun; Lin, Xiao; Zhao, Jing-Tai; Zhang, Guo-Bin

    2013-02-15

    Graphical abstract: Display Omitted Highlights: ► We report the VUV spectroscopic properties of rare-earth ions in K{sub 2}LnZr(PO{sub 4}){sub 3}. ► The O{sup 2−}-Eu{sup 3+} charge transfer bands at about 220 nm have been observed. ► The 4f–5d spin-allowed and spin-forbidden transitions of Tb{sup 3+} have been observed. ► There is energy transfer between the host and rare-earth activators. -- Abstract: Rare earth (RE = Sm, Eu, Tb, Dy and Tm)-activated K{sub 2}LnZr(PO{sub 4}){sub 3} (Ln = Y, La, Gd and Lu) have been synthesized by solid-state reaction method, and their vacuum ultraviolet (VUV) excitation luminescent characteristics have been investigated. The band in the wavelength range of 130–157 nm and the other one range from 155 to 216 nm with the maximum at about 187 nm in the VUV excitation spectra of these compounds are attributed to the host lattice absorption and O–Zr charge transfer transition, respectively. The charge transfer bands (CTB) of O{sup 2−}-Sm{sup 3+}, O{sup 2−}-Dy{sup 3+} and O{sup 2−}-Tm{sup 3+}, in Sm{sup 3+}, Dy{sup 3+} and Tm{sup 3+}-activated samples, have not been obviously observed probably because the 2p electrons of oxygen are tightly bound to the zirconium ion in the host lattice. For Eu{sup 3+}-activated samples, the relatively weak O{sup 2−}-Eu{sup 3+} CTB at about 220 nm is observed. And for Tb{sup 3+}-activated samples, the bands at 223 and 258 nm are related to the 4f-5d spin-allowed and spin-forbidden transitions of Tb{sup 3+}, respectively. It is observed that there is energy transfer between the host lattice and the luminescent activators (e.g. Eu{sup 3+}, Tb{sup 3+}). From the standpoint of luminescent efficiency, color purity and chemical stability, K{sub 2}GdZr(PO{sub 4}){sub 3}:Sm{sup 3+}, Eu{sup 3+}, Tb{sup 3+} are attractive candidates for novel yellow, red, green-emitting PDP phosphors.

  4. An investigation of structural parameters and magnetic and optical properties of EuLn{sub 2}Q{sub 4} (Ln=Tb-Lu, Q=S, Se)

    SciTech Connect

    Jin Gengbang; Choi, Eun Sang; Guertin, Robert P.; Albrecht-Schmitt, Thomas E.

    2008-01-15

    EuLn{sub 2}Q{sub 4} (Ln=Tb-Lu; Q=S, Se) has been synthesized using Sb{sub 2}Q{sub 3} (Q=S, Se) fluxes at 1000 deg. C. These compounds crystallize in a CaFe{sub 2}O{sub 4}-type three-dimensional channel structure that is built from edge-shared double rutile chains of [LnQ{sub 6}] octahedra running down the b-axis. Each double chain is connected at the vertices to four other double chains to form open channels where bicapped trigonal prismatic Eu{sup 2+} ions reside. All of these compounds show antiferromagnetic ordering with Neel temperatures, T{sub N}{approx}3-4 K. The optical band gaps for EuTb{sub 2}Se{sub 4}, EuDy{sub 2}Se{sub 4}, EuHo{sub 2}Se{sub 4}, EuEr{sub 2}Se{sub 4}, EuTm{sub 2}Se{sub 4}, EuYb{sub 2}Se{sub 4} EuLu{sub 2}Se{sub 4}, and EuYb{sub 2}S{sub 4} are found to be 2.0, 1.8, 1.8, 1.7, 1.8, 1.3, 1.7, and 1.6 eV, respectively. - Graphical abstract: A view of the three-dimensional channel structure of EuYb{sub 2}S{sub 4} down the b-axis.

  5. Structural and Magnetothermal Properties of Compounds: Yb5SixGe4-x,Sm5SixGe4-x, EuO, and Eu3O4

    SciTech Connect

    Ahn, Kyunghan

    2007-01-01

    The family of R5SixGe4-x alloys demonstrates a variety of unique physical phenomena related to magneto-structural transitions associated with reversible breaking and reforming of specific bonds that can be controlled by numerous external parameters such as chemical composition, magnetic field, temperature, and pressure. Therefore, R5SixGe4-x systems have been extensively studied to uncover the mechanism of the extraordinary magneto-responsive properties including the giant magnetoresistance (GMR) and colossal magnetostriction, as well as giant magnetocaloric effect (GMCE). Until now, more than a half of possible R5SixGe4-x pseudobinary systems have been completely or partially investigated with respect to their crystallography and phase relationships (R = La, Pr, Nd, Gd, Tb, Dy, Er, Lu, Y). Still, there are other R5SixGe4-x systems (R = Ce, Sm, Ho, Tm, and Yb) that are not studied yet. Here, we report on phase relationships and structural, magnetic, and thermodynamic properties in the Yb5SixGe4-xand Sm5SixGe4-x pseudobinary systems, which may exhibit mixed valence states. The crystallography, phase relationships, and physical properties of Yb5SixGe4-x alloys with 0 ≤ x ≤ 4 have been examined by using single crystal and powder x-ray diffraction at room temperature, and dc magnetization and heat capacity measurements between 1.8 K and 400 K in magnetic fields ranging from 0 to 7 T. Unlike the majority of R5SixGe4-x systems studied to date, where R is the rare earth metal, all Yb-based germanide-silicides with the 5:4 stoichiometry crystallize in the same Gd5Si4-type structure. The magnetic properties of Yb5SixGe4-x materials are nearly composition

  6. Near infrared emission of TbAG:Ce3+,Yb3+ phosphor for solar cell applications

    NASA Astrophysics Data System (ADS)

    Meshram, N. D.; Yadav, P. J.; Pathak, A. A.; Joshi, C. P.; Moharil, S. V.

    2016-05-01

    Luminescent materials doped with rare earth ions are used for many devices such as optical amplifiers in telecommunication, phosphors for white light emitting diodes (LEDs), displays, and so on. Recently, they also have attracted a great interest for photovoltaic applications to improve solar cell efficiency by modifying solar spectrum. Crystal silicon (c-Si) solar cells most effectively convert photons of energy close to the semiconductor band gap. The mis-match between the incident solar spectrum and the spectral response of solar cells is one of the main reasons to limit the cell efficiency. The efficiency limit of the c-Si has been estimated to be 29% by Shockley and Queisser. However, this limit is estimated to be improved up to 38.4% by modifying the solar spectrum by a quantum cutting (down converting) phosphor which converts one photon of high energy into two photons of lower energy. The phenomenon such as the quantum cutting or the down conversion of rare earth ions have been investigated since Dexter reported the possibility of a luminescent quantum yield greater than unity in 1957. In the past, the quantum cutting from a vacuum ultraviolet photon to visible photons for Pr3+, Gd3+,Gd3+-Eu3+, and Er3+-Tb3+ had been studied. Recently, a new quantum cutting phenomenon from visible photon shorter than 500 nm to two infrared photons for Tb3+-Yb3+, Pr3+-Yb3+, and Tm3+-Yb3+ has been reported. The Yb3+ ion is suitable as an acceptor and emitter because luminescent quantum efficiency of Yb3+ is close to 100% and the energy of the only excited level of Yb3+ (1.2 eV) is roughly in accordance with the band gap of Si (1.1 eV). In addition, the Ce3+-doped Tb3Al5O12 (TbAG), used as a phosphor for white LED, has broad absorption bands in the range of 300-500 nm due to strong ligand field and high luminescent quantum efficiency. Therefore, the Ce3+ ions in the TbAG can be suitable as an excellent sensitizing donor for down conversion materials of Si solar cells. In this

  7. Complexation behavior of Eu(III), Tb(III), Tm(III), and Am(III) with three 1,10-phenanthroline-type ligands: insights from density functional theory.

    PubMed

    Yang, Yanqiu; Fang, Yu; Liu, Jun; Hu, Shiyuan; Hu, Sheng; Yang, Liang; Wang, Dawei; Zhang, Huabei; Luo, Shunzhong

    2015-07-01

    Extraction complexes of Eu(III), Tb(III), Tm(III), and Am(III) with three 1,10-phenanthroline-type ligands have been studied, primarily using density functional theory (DFT). The same accuracies and optimized structural geometries were obtained whether optimization of the [ML2(NO3)](2+) complexes was performed at the B3LYP/6-31G(d)/RECP or the MP2/6-31G(d)/RECP level of theory. Calculations carried out at the B3LYP/6-311G(d, p)/RECP level of theory indicated that solvation does not favor the formation of these complexes. Moreover, the ΔGg and ΔGsolv values for the reactions leading to the formation of [LnL2(NO3)](2+) complexes were seen to decrease with increasing atomic number of the lanthanide (from Eu to Tb to Tm). In addition, when a strongly hydrophobic benzo[e][1,2,4]triazine group was created in each ligand, ligand selectivity for actinides/lanthanides in acidic media improved. Even greater ligand selectivity for actinides/lanthanides in acidic media was obtained when a 5,6-diphenyl-1,2,4-triazine group was created in each ligand instead of a benzo[e][1,2,4]triazine group. Vibrational analysis and NMR spectroscopic analysis were also performed on all of the studied ligands and the metal complexes that included them. Further in-depth investigations should be undertaken in this field. PMID:26141789

  8. Development of the EpiOcular(TM) eye irritation test for hazard identification and labelling of eye irritating chemicals in response to the requirements of the EU cosmetics directive and REACH legislation.

    PubMed

    Kaluzhny, Yulia; Kandárová, Helena; Hayden, Patrick; Kubilus, Joseph; d'Argembeau-Thornton, Laurence; Klausner, Mitchell

    2011-09-01

    The recently implemented 7th Amendment to the EU Cosmetics Directive and the EU REACH legislation have heightened the need for in vitro ocular test methods. To address this need, the EpiOcular(TM) eye irritation test (EpiOcular-EIT), which utilises the normal (non-transformed) human cell-based EpiOcular tissue model, has been developed. The EpiOcular-EIT prediction model is based on an initial training set of 39 liquid and 21 solid test substances and uses a single exposure period and a single cut-off in tissue viability, as determined by the MTT assay. A chemical is classified as an irritant (GHS Category 1 or 2), if the tissue viability is ≤ 60%, and as a non-irritant (GHS unclassified), if the viability is > 60%. EpiOcular-EIT results for the training set, along with results for an additional 52 substances, which included a range of alcohols, hydrocarbons, amines, esters, and ketones, discriminated between ocular irritants and non-irritants with 98.1% sensitivity, 72.9% specificity, and 84.8% accuracy. To ensure the long-term commercial viability of the assay, EpiOcular tissues produced by using three alternative cell culture inserts were evaluated in the EpiOcular-EIT with 94 chemicals. The assay results obtained with the initial insert and the three alternative inserts were very similar, as judged by correlation coefficients (r²) that ranged from 0.82 to 0.96. The EpiOcular-EIT was pre-validated in 2007/2008, and is currently involved in a formal, multi-laboratory validation study sponsored by the European Cosmetics Association (COLIPA) under the auspices of the European Centre for the Validation of Alternative Methods (ECVAM). The EpiOcular-EIT, together with EpiOcular's long history of reproducibility and proven utility for ultra-mildness testing, make EpiOcular a useful model for addressing current legislation related to animal use in the testing of potential ocular irritants.

  9. Chemical bond parameters and photoluminescence of a natural-white-light Ca{sub 9}La(VO{sub 4}){sub 7}:Tm{sup 3+},Eu{sup 3+} with one O{sup 2−}→V{sup 5+} charge transfer and dual f-f transition emission centers

    SciTech Connect

    Li, Ling; Liu, Xiao Guang; Noh, Hyeon Mi; Jeong, Jung Hyun

    2015-01-15

    The relationship between the photoluminescence properties and the crystal structure of undoped, Eu{sup 3+} or/ and Tm{sup 3+} singly or codoped Ca{sub 9}La(VO{sub 4}){sub 7} (CLaVO) samples was discussed. Under the excitation of UV light, CLaVO:Tm{sup 3+}, CLaVO, and CLaVO:Eu{sup 3+} exhibit the characteristic emissions of Tm{sup 3+} ({sup 1}G{sub 4}→{sup 3}H{sub 6}, blue), O{sup 2−}→V{sup 5+} charge transfer (CT), and Eu{sup 3+} ({sup 5}D{sub 0}→{sup 7}F{sub 2}, red), respectively. By adjusting the doping concentration of Tm{sup 3+} and Eu{sup 3+} ions in CLaVO, a natural white emission in a single composition with the color temperature at 6181 K was obtained. Based on the dielectric theory of complex crystal, the chemical bond parameters of La-O and V-O bonds were quantitatively calculated. The standard deviation of environmental factor of every bond (EFSD), which can be expressed as σ(h{sub e{sub i}})=√((1/N)∑{sub i=1}{sup N}(h{sub e{sub i}}−μ){sup 2}) (h{sub e{sub i}}=(f{sub c{sub i}}α{sub b{sub i}}){sup 1/2}Q{sub B{sub i}} and μ=(1/N)∑{sub i=1}{sup N}h{sub e{sub i}}), was proposed to quantitatively express the distortion degree of VO{sub 4}{sup 3−} from that of an ideal tetrahedron. The maximum change of EFSD comes from the [VO{sub 4}]{sup −} tetrahedra in CLaVO sample by comparison with that of EFSD of isostructural Ca{sub 9}Gd(VO{sub 4}){sub 7}. This is possible the key reason that the undoped CLaVO sample has self-activated emission while the self-activated emission of its isostructural Ca{sub 9}Gd(VO{sub 4}){sub 7} sample cannot be found. The quantitative calculation also demonstrated that the broad excitation bands at 319 nm in CLaVO:Tm and at 335 nm in CLaVO:Eu were due to the O-V2 and O-V3 (overlap with O-V2) CT, not the CT energy of O{sup 2−}-Eu1{sup 3+} (O{sup 2−}-Tm1{sup 3+}), O{sup 2−}-Eu2{sup 3+} (O{sup 2−}-Tm2{sup 3+}), and O{sup 2−}-Eu3{sup 3+} (O{sup 2−}-Tm3{sup 3+}). The environmental factors surrounding the

  10. tmRDB (tmRNA database).

    PubMed

    Knudsen, B; Wower, J; Zwieb, C; Gorodkin, J

    2001-01-01

    The tmRNA database (tmRDB) is maintained at the University of Texas Health Science Center at Tyler, Texas, and accessible on the World Wide Web at the URL http://psyche.uthct.edu/dbs/tmRDB/tmRDB.++ +html. Mirror sites are located at Auburn University, Auburn, Alabama (http://www.ag.auburn.edu/mirror/tmRDB/) and the Institute of Biological Sciences, Aarhus, Denmark (http://www.bioinf.au. dk/tmRDB/). The tmRDB provides information and citation links about tmRNA, a molecule that combines functions of tRNA and mRNA in trans-translation. tmRNA is likely to be present in all bacteria and has been found in algae chloroplasts, the cyanelle of Cyanophora paradoxa and the mitochondrion of the flagellate Reclinomonas americana. This release adds 26 new sequences and corresponding predicted tmRNA-encoded tag peptides for a total of 86 tmRNAs, ordered alphabetically and phylogenetically. Secondary structures and three-dimensional models in PDB format for representative molecules are being made available. tmRNA alignments prove individual base pairs and are generated manually assisted by computational tools. The alignments with their corresponding structural annotation can be obtained in various formats, including a new column format designed to improve and simplify computational usability of the data.

  11. Triaxial strongly deformed bands in {sup 160,161}Tm

    SciTech Connect

    Teal, C.; Lagergren, K.; Aguilar, A.; Riley, M. A.; Hartley, D. J.; Simpson, J.; Joss, D. T.; Carpenter, M. P.; Janssens, R. V. F.; Lauritsen, T.; Lister, C. J.; Zhu, S.; Garg, U.; Kondev, F. G.; Wang, X.; Ragnarsson, I.

    2008-07-15

    High-spin states in {sup 160,161}Tm were populated using the {sup 128}Te({sup 37}Cl, 5n and 4n) reactions at a beam energy of 170 MeV. Emitted {gamma} rays were detected in the Gammasphere spectrometer. Two rotational bands with high moments of inertia were discovered, one assigned to {sup 160}Tm, while the other tentatively assigned to {sup 161}Tm. These sequences display features similar to bands observed in neighboring Er, Tm, Yb, and Lu nuclei which have been discussed in terms of triaxial strongly deformed structures. Cranked Nilsson Strutinsky calculations have been performed that predict well-deformed triaxial shapes at high spin in {sup 160,161}Tm.

  12. Glass-ceramic nuclear waste forms obtained by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th): Study of the crystallization from the surface

    NASA Astrophysics Data System (ADS)

    Loiseau, P.; Caurant, D.

    2010-07-01

    Glass-ceramic materials containing zirconolite (nominally CaZrTi 2O 7) crystals in their bulk can be envisaged as potential waste forms for minor actinides (Np, Am, Cm) and Pu immobilization. In this study such matrices are synthesized by crystallization of SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th) as surrogates. A thin partially crystallized layer containing titanite and anorthite (nominally CaTiSiO 5 and CaAl 2Si 2O 8, respectively) growing from glass surface is also observed. The effect of the nature and concentration of surrogates on the structure, the microstructure and the composition of the crystals formed in the surface layer is presented in this paper. Titanite is the only crystalline phase able to significantly incorporate trivalent lanthanides whereas ThO 2 precipitates in the layer. The crystal growth thermal treatment duration (2-300 h) at high temperature (1050-1200 °C) is shown to strongly affect glass-ceramics microstructure. For the system studied in this paper, it appears that zirconolite is not thermodynamically stable in comparison with titanite growing form glass surface. Nevertheless, for kinetic reasons, such transformation (i.e. zirconolite disappearance to the benefit of titanite) is not expected to occur during interim storage and disposal of the glass-ceramic waste forms because their temperature will never exceed a few hundred degrees.

  13. Glass-ceramic nuclear waste forms obtained from SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 glasses containing lanthanides (Ce, Nd, Eu, Gd, Yb) and actinides (Th): study of internal crystallization

    NASA Astrophysics Data System (ADS)

    Loiseau, P.; Caurant, D.; Baffier, N.; Mazerolles, L.; Fillet, C.

    2004-10-01

    Glass-ceramic waste forms such as zirconolite (nominally CaZrTi 2O 7) based ones can be envisaged as good candidates for minor actinides or Pu immobilization. Such materials, in which the actinides (or lanthanides used as actinide surrogates) would be preferentially incorporated into zirconolite crystals homogeneously dispersed in a durable glassy matrix, can be prepared by controlled crystallization (nucleation + crystal growth) of parent glasses belonging to the SiO 2-Al 2O 3-CaO-ZrO 2-TiO 2 system. In this work we present the effects of the nature of the minor actinide surrogate (Ce, Nd, Eu, Gd, Yb, Th) on the structure, the microstructure and the composition of the zirconolite crystals formed in the bulk of the glass-ceramics. The amount of lanthanides and thorium incorporated into zirconolite crystals is discussed in relation with the capacity of the glass to accommodate these elements and of the crystals to incorporate them in the calcium and zirconium sites of their structure.

  14. Uniform and well-dispersed YbVO4 hierarchical nanoarchitectures: synthesis and luminescence properties.

    PubMed

    Xu, Zhenhe; Zhao, Qian; Liu, Tao; Wang, Liming; Bian, Shasha

    2013-01-01

    The YbVO4 micro-doughnuts were successfully fabricated by a facile hydrothermal method. X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and photoluminescence (PL) were used to characterize the resulting samples. The diameter and thickness of YbVO4 micro-doughnuts are around 750 nm and 480 nm, respectively. It is found that trisodium citrate (Na3Cit) is essential for obtaining YbVO4 microdoughnuts. Moreover, the crystal growth process was thoroughly discussed through a series of time-dependent experiments and a possible formation mechanism was proposed. Furthermore, the up-conversion (UC) luminescent properties as well as the emission mechanisms of YbVO4:Ln3+ (Ln3+ = Er3+, Tm3+ and Ho3+) microcrystals were systematically investigated.

  15. High Pressure Measurements of the Resistivity of β-YbAlB4

    NASA Astrophysics Data System (ADS)

    Tomita, T.; Kuga, K.; Uwatoko, Y.; Nakatsuji, S.

    2015-03-01

    The electric resistivity ρ(T) under hydrostatic pressure up to 8 GPa was measured above 2 K using a high-quality single crystal of the Yb-based heavy fermion system β-YbAlB4. We found pressure-induced magnetic ordering above the critical pressure Pc ≈ 2.4 GPa. This phase transition temperature TM is enhanced with pressure and reaches 30 K at a pressure of 8 GPa, which is the highest transition temperature for the Yb-based heavy fermion compounds. In contrast, the resistivity is insensitive to pressure below Pc and exhibits the T-linear behavior in the temperature range between 2 and 20 K. Our results indicate that quantum criticality for β-YbAlB4 is also located near Pc in addition to the ambient pressure.

  16. Optical study of archetypical valence-fluctuating Eu systems.

    PubMed

    Guritanu, V; Seiro, S; Sichelschmidt, J; Caroca-Canales, N; Iizuka, T; Kimura, S; Geibel, C; Steglich, F

    2012-12-14

    We have investigated the optical conductivity of the prominent valence-fluctuating compounds EuIr(2)Si(2) and EuNi(2)P(2) in the infrared energy range to get new insights into the electronic properties of valence-fluctuating systems. For both compounds, we observe upon cooling the formation of a renormalized Drude response, a partial suppression of the optical conductivity below 100 meV, and the appearance of a midinfrared peak at 0.15 eV for EuIr(2)Si(2) and 0.13 eV for EuNi(2)P(2). Most remarkably, our results show a strong similarity with the optical spectra reported for many Ce- or Yb-based heavy-fermion metals and intermediate valence systems, although the phase diagrams and the temperature dependence of the valence differ strongly between Eu systems and Ce- or Yb-based systems. This suggests that the hybridization between 4f and conduction electrons, which is responsible for the properties of Ce and Yb systems, plays an important role in valence-fluctuating Eu systems.

  17. Damping in Yb nuclei

    SciTech Connect

    Stephens, F.S.; Deleplanque, M.A.; Lee, I.Y.; Ward, D.; Fallon, P.; Cromaz, M.; Macchiavelli, A.O.; Clark, R.M.; Diamond, R.M.; Gorgen, A.

    2002-07-01

    In a mixture of three Yb nuclei, we find the rotational damping widths vary from 180 keV at 1.1 MeV {gamma}-ray energy to 290 keV at 1.5 MeV, and the average compound damping widths (or spreading widths) vary from 40 keV at 1.1 MeV {gamma}-ray energy to 60 keV at 1.3 MeV. The simulations also suggest extensive motional narrowing.

  18. Sulfate Exchange of the Nitrate-Type Layered Hydroxide Nanosheets of Ln2(OH)5NO3· nH2O for Better Dispersed and Multi-color Luminescent Ln2O3 Nanophosphors (Ln = Y0.98RE0.02, RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm)

    NASA Astrophysics Data System (ADS)

    Wu, Xiaoli; Liu, Weigang; Li, Ji-Guang; Zhu, Qi; Li, Xiaodong; Sun, Xudong

    2016-07-01

    Through restricting thickness growth by performing coprecipitation at the freezing temperature of ~4 °C, solid-solution nanosheets (up to 5-nm thick) of the Ln2(OH)5NO3· nH2O layered hydroxide (Ln = Y0.98RE0.02; RE = Pr, Sm, Eu, Tb, Dy, Ho, Er, and Tm, respectively) were directly synthesized without performing conventional exfoliation. In situ exchange of the interlayer NO3 - with SO4 2- produced a sulfate derivative [Ln2(OH)5(SO4)0.5· nH2O] of the same layered structure and two-dimensional crystallite morphology but substantially contracted d 002 basal spacing (from ~0.886 to 0.841 nm). The sulfate derivative was systematically compared against its nitrate parent in terms of crystal structure and phase/morphology evolution upon heating. It is shown that the interlayer SO4 2-, owing to its bonding with the hydroxide main layer, significantly raises the decomposition temperature from ~600 to 1000 °C to yield remarkably better dispersed oxide nanopowders via a monoclinic Ln2O2SO4 intermediate. The resultant (Y0.98RE0.02)2O3 nanophosphors were studied for their photoluminescence to show that the emission color, depending on RE3+, spans a wide range in the Commission Internationale de l'Eclairage (CIE) chromaticity diagram, from blue to deep red via green, yellow, orange, and orange red.

  19. Ultraviolet upconversion luminescence of Gd{sup 3+} and Eu{sup 3+} in nano-structured glass ceramics

    SciTech Connect

    Lin, Hang; Chen, Daqin; Yu, Yunlong; Yang, Anping; Zhang, Rui; Wang, Yuansheng

    2012-02-15

    Highlights: Black-Right-Pointing-Pointer Ultraviolet upconversion emissions of Eu{sup 3+} and Gd{sup 3+} are rarely studied. Black-Right-Pointing-Pointer Nanostructured glass ceramic is developed as a host for ultraviolet upconversion. Black-Right-Pointing-Pointer Ultraviolet upconversion signal are found greatly enhanced after crystallization. Black-Right-Pointing-Pointer It is promising for fabricating novel ultraviolet upconversion lasers. -- Abstract: Ultraviolet multiphoton upconversion emissions of Eu{sup 3+} ({sup 5}H{sub 3-7}, {sup 5}G{sub 2-6}, {sup 5}L{sub 6} {yields} {sup 7}F{sub 0}) and Gd{sup 3+} ({sup 6}I{sub J}, {sup 6}P{sub J} {yields} {sup 8}S{sub 7/2}) are studied in the Eu{sup 3+} (or Gd{sup 3+}) doped SiO{sub 2}-Al{sub 2}O{sub 3}-NaF-YF{sub 3} precursor glasses and glass ceramics containing {beta}-YF{sub 3} nanocrystals, under continuous-wavelength 976 nm laser pumping. It is experimentally demonstrated that energy transfer from Yb{sup 3+} to Tm{sup 3+}, then further to Eu{sup 3+} or Gd{sup 3+} is responsible for the upconversion process. Compared to those in the precursor glasses, the upconversion emission intensities in the glass ceramics are greatly enhanced, owing to the participation of rare earth ions into the low-phonon-energy environment of {beta}-YF{sub 3} nanocrystals. Hopefully, the studied glass ceramics may find potential applications in the field of ultraviolet solid-state lasers.

  20. Pressure dependence of the emission in CaF2 : Yb2+

    NASA Astrophysics Data System (ADS)

    Mahlik, S.; Lazarowska, A.; Grinberg, M.; Wells, J.-P. R.; Reid, M. F.

    2015-08-01

    We present a detailed spectroscopic investigation of CaF2 doped with Yb2+ performed at high hydrostatic pressure which is applied in a diamond anvil cell. At ambient pressure and at temperatures lower than 175 K, the luminescence consists of a single broad band peaked at 18 500 cm-1, attributed to the recombination of impurity-trapped excitons. Increasing pressure causes the luminescence to be observable at higher temperature. At a pressure of 72 kbar luminescence can be observed up to 275 K. The emission lineshape does not strongly depend on pressure below 85 kbar. However, at 85 kbar it is blue shifted to 21 630 cm-1. This is attributed to the known phase transition of the CaF2 crystal from cubic to the orthorhombic phase. The absolute energy of the ground and 4f135d states of Yb2+ as well as the energy of the impurity-trapped exciton with respect to valence and conduction bands have been estimated. The results, are discussed in comparison with the pressure dependences observed for the luminescence of BaF2 : Eu2+ and CaF2 : Eu2+. The difference between the spectral properties of Eu2+ and Yb2+ is attributable to the fact that the ground and 4f65d states of Eu2+ are placed deeper in the CaF2 bandgap than the ground and excited 4f135d states of Yb2+, whereas the energies of the impurity-trapped exciton states for Yb2+ and Eu2+ with respect to the conduction band are approximately the same.

  1. CLOMP_TM

    2012-06-01

    The CLOMP_TM benchmark was developed to measure the overheads of various mechanisms used to guarantee the generation of correct results in threaded code even when multiple threads might be accessing and/or updating the same memory location at the same time. This includes widely supported mechanisms like OpenMP Atomic and Open MP Critical as well as new mechanisms like Transactional Memory (TM) and Speculative Execution (SE) of threads. The CLOMP_TM benchmark is highly configurable to allowmore » a variety of problem sizes, atomic update region sizes, and potential race condition opportunities to be studied. A wide variety of checks are done on the results to verify the expected answer was actuallyl generated. Thus CLOMP_TM can be used both to measure the overhead for various mechanisms and to check the correctness of their implementation.« less

  2. A broadening temperature sensitivity range with a core-shell YbEr@YbNd double ratiometric optical nanothermometer

    NASA Astrophysics Data System (ADS)

    Marciniak, L.; Prorok, K.; Francés-Soriano, L.; Pérez-Prieto, J.; Bednarkiewicz, A.

    2016-02-01

    The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle based optical nano-thermometer under single ~808 nm wavelength photo-excitation from around ΔT = 150 K to over ΔT = 300 K (150-450 K). Such engineered nanocrystals are suitable for remote optical temperature measurements in technology and biotechnology at the sub-micron scale.The chemical architecture of lanthanide doped core-shell up-converting nanoparticles can be engineered to purposely design the properties of luminescent nanomaterials, which are typically inaccessible to their homogeneous counterparts. Such an approach allowed to shift the up-conversion excitation wavelength from ~980 to the more relevant ~808 nm or enable Tb or Eu up-conversion emission, which was previously impossible to obtain or inefficient. Here, we address the issue of limited temperature sensitivity range of optical lanthanide based nano-thermometers. By covering Yb-Er co-doped core nanoparticles with the Yb-Nd co-doped shell, we have intentionally combined temperature dependent Er up-conversion together with temperature dependent Nd --> Yb energy transfer, and thus have expanded the temperature response range ΔT of a single nanoparticle

  3. Extension of excitation functions up to 50 MeV for activation products in deuteron irradiations of Pr and Tm targets

    NASA Astrophysics Data System (ADS)

    Hermanne, A.; Tárkányi, F.; Takács, S.; Ditrói, F.

    2016-09-01

    Extension up to 50 MeV incident deuteron energy is presented for excitation functions of activation products formed in monoisotopic Tm (169Tm) and Pr (141Pr). By stacked foil irradiations direct and/or cumulative production of 140,139m,138Nd, 138mPr, 141,139,137m,135Ce on Pr and 166,169Yb, 166,167,168Tm on Tm targets were measured. Confirmation of earlier experimental results for all investigated radionuclides is found and the influence of the higher energy on thick target yields and batch production of medically relevant radionuclides (140Nd, 139Pr (as decay product of 139mNd), 166,169Yb, 167Tm) is discussed. A comparison of experimental values with TALYS1.6 code results (predicted values from TENDL-2015 on-line library) shows a better description of the (d,pxn) reactions than older ones.

  4. Yb:S-FAP Lasers

    SciTech Connect

    Schaffers, K I

    2004-01-20

    It has recently been reported that several high power, diode-pumped laser systems have been developed based on crystals of Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F]. The Mercury Laser, at Lawrence Livermore National Laboratory, is the most prominent system using Yb:S-FAP and is currently producing 23J at 5 Hz in a 15 nsec pulse, based on partial activation of the system. In addition, a regenerative amplifier is being developed at Waseda University in Japan and has produced greater than 12 mJ with high beam quality at 50Hz repetition rate. Q-peak has demonstrated 16 mJ of maximum energy/output pulse in a multi-pass, diode side-pumped amplifier and ELSA in France is implementing Yb:S-FAP in a 985 nm pump for an EDFA, producing 250 mW. Growth of high optical quality crystals of Yb:S-FAP is a challenge due to multiple crystalline defects. However, at this time, a growth process has been developed to produce high quality 3.5 cm diameter Yb:S-FAP crystals and a process is under development for producing 6.5 cm diameter crystals.

  5. Thermoelectric Properties of Yb_14MnSb_11

    NASA Astrophysics Data System (ADS)

    Carr, C. W.; Klavins, P.; Shelton, R. N.; Kauzlarich, S. M.; Snyder, G. J.

    2000-03-01

    A class of compounds with the general formula R_14MnPn_11 (where R=Eu, Yb, Ca, Sr, Ba and Pn=P, As, Sb, Bi) have been studied for their interesting structural and magnetic properties.(Kauzlarich, S.M., Chemistry, Structure, and Bonding of Zintl Phases and Ions, (VCH Publishers, New York, 1996).) The compounds range from semiconducting to metallic across the series and exhibit colossal magnetoresistive properties at low temperatures. Preliminary measurements of one of these compounds, Yb_14MnSb_11, indicate that it may have potential as a new thermoelectric material. Recently it has been shown that atomic displacement parameters can be used to calculate the thermal conductivity of materials and that this method may prove useful in identifying new thermoelectric materials.(Sales, B.C., et al., J. Solid State Chem., vol. 146 (1999).) We utilize this method to estimate the thermal properties for the Zintl compound Yb_14MnSb_11. The estimated values will be compared with values measured by the 3-omega method.

  6. Thermal expansion of a Au-Al-Yb intermediate valence quasicrystal

    NASA Astrophysics Data System (ADS)

    Watanuki, T.; Kashimoto, S.; Ishimasa, T.; Machida, A.; Yamamoto, S.; Tanaka, Y.; Mizumaki, M.; Kawamura, N.; Watanabe, S.

    2015-06-01

    The thermal expansion of a Au-Al-Yb intermediate-valence quasicrystal has been studied. X-ray diffraction measurements showed zero thermal expansion below 50 K. By comparison with an isostructural Au-Al-Tm quasicrystal, the contribution of the Yb valence variation was extracted, and it was shown that its negative thermal expansion component compensated for the positive thermal expansion of the original lattice. On cooling, the Yb contribution grew steeply below approximately 155 K down to the lowest experimental temperature of 5 K, due to enlargement of the Yb atomic radius, which was caused by the valence shift toward the divalent state. Additionally, a larger Yb contribution to the thermal expansion was demonstrated in a crystalline approximant to this quasicrystal. The magnitude of this contribution was approximately 1.4 times larger than in the case of the quasicrystal itself, resulting in a slight negative thermal expansion below 50 K. A heterogeneous valence model for the quasicrystal that we proposed previously accounts for this magnitude difference.

  7. Rare earth-copper-magnesium compounds RECu 9Mg 2 ( RE=Y, La-Nd, Sm-Ho, Yb) with ordered CeNi 3-type structure

    NASA Astrophysics Data System (ADS)

    Solokha, P.; Pavlyuk, V.; Saccone, A.; De Negri, S.; Prochwicz, W.; Marciniak, B.; Różycka-Sokołowska, E.

    2006-10-01

    A series of ternary compounds RECu 9Mg 2 ( RE=Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Yb) have been synthesized via induction melting of elemental metal ingots followed by annealing at 400 °C for 4 weeks. Scanning electron microscopy (SEM) coupled with energy dispersive X-ray spectroscopy (EDXS) was used for examining microstructure and phase composition. These phases crystallize with an ordered version of the binary hexagonal structure type first reported for CeNi 3. The crystal structure was solved for TbCu 9Mg 2 from single crystal X-ray counter data (TbCu 9Mg 2-structure type, P6 3/mmc-space group, hP24-Pearson symbol, a=0.49886 (7) nm, c=1.61646 (3) nm, RF=0.0474 for 190 unique reflections). The Rietveld refinement of the X-ray powder diffraction patterns of RECu 9Mg 2 confirmed the same crystal structure for the reported rare earth metals. The unit cell volumes for RECu 9Mg 2 smoothly follow the lanthanide contraction. The existence of a RECu 9Mg 2 phase was excluded for RE=Er and Tm under the investigated experimental conditions.

  8. GEOMAG[TM] Paradoxes

    ERIC Educational Resources Information Center

    Defrancesco, Silvia; Logiurato, Fabrizio; Karwasz, Grzegorz

    2007-01-01

    As often happens, a lot of physics can come out of a toy. What we found interesting is the observation of the magnetic field produced by different configurations built with GEOMAG[TM]. This toy provides small magnetic bars and steel spheres to play with. Amusing 3-D structures can be built; nevertheless, this possibility is not so obvious. Indeed,…

  9. Highly Efficient Tm-Doped Yttrium Aluminum Garnet Ceramic Laser Based on the Novel Fiber-Bulk Hybrid Configuration

    NASA Astrophysics Data System (ADS)

    Liu, Jun; Shen, Deyuan; Huang, Haitao; Zhang, Xiaoqi; Tang, Dingyuan; Fan, Dianyuan

    2013-09-01

    A polycrystalline ceramic Tm3+-doped yttrium aluminum garnet (Tm:Y3Al5O12, Tm:YAG) laser based on the novel fiber-bulk hybrid configuration is demonstrated using a high-power and tunable Er,Yb co-doped fiber laser as the pump source. Lasing characteristics of a 4.0 at. % Tm:YAG ceramic are investigated at different pump wavelengths from 1617 to 1625 nm. With an output coupler of 10% transmission, a maximum output power of 3.9 W is obtained at 2013.2 nm under an 8.8 W incident pump power at the Tm:YAG absorption peak of 1620.4 nm, corresponding to a slope efficiency of 50.1% with respect to the incident pump power.

  10. Fabrication of Yb-123 Tapes

    SciTech Connect

    Athur, S.; Balachandran, U.; Salama, K.

    2000-11-15

    While Bi-2223 tapes have been the workhorses of the superconductor industry, their poor performance in applied magnetic fields restrict their use to below 30 K. Melt-processing of Ag-clad Yb-123 PIT tapes offers a simple and scalable technique for fabricating long-length HTS conductors capable of being used at 77 K. Under reduced oxygen partial pressure, the peritectic temperature of Yb-123 is below the melting point of Ag, and this facilitates the adaptation of melt-texturing methods for fabricating these tapes. The effect of melt-processing temperature on current density was also explored; a temperature of 965 C yielded optimal critical current values. The critical current density achieved at 4.2 K was 20,000 A/cm{sup 2}, corresponding to a critical current of 52 A. Based on the above results, an optimal processing zone for melt-processing of Ag-clad Yb-123 tapes was determined. These results hold promise for melt-processing of Ag-clad Yb-123 tapes as an alternative to Bi-2223 PIT technology.

  11. Synthesis, crystal structure, and magnetism of A2Co12As7 (A=Ca, Y, Ce-Yb)

    NASA Astrophysics Data System (ADS)

    Tan, Xiaoyan; Ovidiu Garlea, V.; Chai, Ping; Geondzhian, Andrey Y.; Yaroslavtsev, Alexander A.; Xin, Yan; Menushenkov, Alexey P.; Chernikov, Roman V.; Shatruk, Michael

    2016-04-01

    Ternary intermetallics, A2Co12As7 (A=Ca, Y, Ce-Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the Zr2Fe12P7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior of A2Co12As7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100-140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr-Sm to ferromagnetic for A=Ce and Eu-Yb. Polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce2Co12As7 and Nd2Co12As7, respectively.

  12. Optical refrigeration of Yb3+:YAG nanocrystals

    NASA Astrophysics Data System (ADS)

    Nemova, Galina; Kashyap, Raman

    2015-03-01

    We have theoretically investigated the laser cooling process in Yb3+:YAG nanocrystals. We have developed an approach, which permits not only estimate the cooling process in Yb3+:YAG nanocrystals but compare this process with the laser cooling of the Yb3+:YAG bulk samples. The temperature dependences of all parameters of the system are taken into account. The cooperative effects such as re-absorption, the energy migration and cooperative luminescence have been considered.

  13. Upconversion luminescence in Yb 3+-doped yttrium aluminum garnets

    NASA Astrophysics Data System (ADS)

    Xu, Xiaodong; Zhao, Zhiwei; Song, Pingxin; Jiang, Benxue; Zhou, Guoqing; Xu, Jun; Deng, Peizhen; Bourdet, Gilbert; Christophe Chanteloup, Jean; Zou, Ji-Ping; Fulop, Annabelle

    2005-03-01

    In this paper, we present results on upconversion luminescence performed on Yb 3+-doped yttrium aluminum garnets under 940 nm excitation. The upconversion luminescence was ascribed to Yb 3+ cooperative luminescence and the presence of rare earth impurity ions. The cooperative luminescence spectra as a function of Yb concentration were measured and the emission intensity variation with Yb concentration was discussed. Yb 3+ energy migration quenched the cooperative luminescence of Yb:YAG crystals with doping level over 15 at%.

  14. Mode instability thresholds for Tm-doped fiber amplifiers pumped at 790 nm.

    PubMed

    Smith, Arlee V; Smith, Jesse J

    2016-01-25

    We use a detailed numerical model of stimulated thermal Rayleigh scattering to compute mode instability thresholds in Tm(3+)-doped fiber amplifiers. The fiber amplifies 2040 nm light using a 790 nm pump. The cross-relaxation process is strong, permitting power efficiencies of 60%. The predicted instability thresholds are compared with those in similar Yb(3+)-doped fiber amplifiers with 976 nm pump and 1060 nm signal, and are found to be higher, even though the heat load is much higher in Tm-doped amplifiers. The higher threshold in the Tm-doped fiber is attributed to its longer signal wavelength, and to stronger gain saturation, due in part to cross-relaxation heating. PMID:26832480

  15. Mode instability thresholds for Tm-doped fiber amplifiers pumped at 790 nm.

    PubMed

    Smith, Arlee V; Smith, Jesse J

    2016-01-25

    We use a detailed numerical model of stimulated thermal Rayleigh scattering to compute mode instability thresholds in Tm(3+)-doped fiber amplifiers. The fiber amplifies 2040 nm light using a 790 nm pump. The cross-relaxation process is strong, permitting power efficiencies of 60%. The predicted instability thresholds are compared with those in similar Yb(3+)-doped fiber amplifiers with 976 nm pump and 1060 nm signal, and are found to be higher, even though the heat load is much higher in Tm-doped amplifiers. The higher threshold in the Tm-doped fiber is attributed to its longer signal wavelength, and to stronger gain saturation, due in part to cross-relaxation heating.

  16. Thermoluminescence responses of the Yb- and Yb-Tb-doped SiO2 optical fibers to 6-MV photons.

    PubMed

    Sahini, M H; Hossain, I; Wagiran, H; Saeed, M A; Ali, H

    2014-09-01

    Characteristics of the thermoluminescence (TL) responses of Yb- and Yb-Tb-doped optical fibers irradiated with 6MV photons are reported. The concentration of Yb in the Yb-doped optical fiber was 0.26mol%; the concentrations of Yb and Tb in the Yb-Tb-doped optical fiber were 0.62 and 0.2mol%, respectively. The TL dose responses are linear in the dose range 0.5-4Gy. The radiation sensitivity of the Yb-Tb material is almost two orders of magnitude higher than the sensitivity of the material doped with Yb alone.

  17. The tmRNA website

    DOE PAGES

    Hudson, Corey M.; Williams, Kelly P.

    2014-11-05

    We report that the transfer-messenger RNA (tmRNA) and its partner protein SmpB act together in resolving problems arising when translating bacterial ribosomes reach the end of mRNA with no stop codon. Their genes have been found in nearly all bacterial genomes and in some organelles. The tmRNA Website serves tmRNA sequences, alignments and feature annotations, and has recently moved to http: //bioinformatics.sandia.gov/tmrna/. New features include software used to find the sequences, an update raising the number of unique tmRNA sequences from 492 to 1716, and a database of SmpB sequences which are served along with the tmRNA sequence from themore » same organism.« less

  18. The tmRNA website

    SciTech Connect

    Hudson, Corey M.; Williams, Kelly P.

    2014-11-05

    We report that the transfer-messenger RNA (tmRNA) and its partner protein SmpB act together in resolving problems arising when translating bacterial ribosomes reach the end of mRNA with no stop codon. Their genes have been found in nearly all bacterial genomes and in some organelles. The tmRNA Website serves tmRNA sequences, alignments and feature annotations, and has recently moved to http: //bioinformatics.sandia.gov/tmrna/. New features include software used to find the sequences, an update raising the number of unique tmRNA sequences from 492 to 1716, and a database of SmpB sequences which are served along with the tmRNA sequence from the same organism.

  19. The tmRNA website.

    PubMed

    Hudson, Corey M; Williams, Kelly P

    2015-01-01

    The transfer-messenger RNA (tmRNA) and its partner protein SmpB act together in resolving problems arising when translating bacterial ribosomes reach the end of mRNA with no stop codon. Their genes have been found in nearly all bacterial genomes and in some organelles. The tmRNA Website serves tmRNA sequences, alignments and feature annotations, and has recently moved to http://bioinformatics.sandia.gov/tmrna/. New features include software used to find the sequences, an update raising the number of unique tmRNA sequences from 492 to 1716, and a database of SmpB sequences which are served along with the tmRNA sequence from the same organism.

  20. Structure and bonding in Yb4MgGe4: Yb2+/Yb3+ mixed-valency and charge separation.

    PubMed

    Tobash, Paul H; Bobev, Svilen

    2006-03-22

    Reported are the synthesis and the structural characterization of a new derivative of the RE5Tt4 family (RE = Rare-earth; Tt = Tetrel, = Si, Ge, i.e., group 14 element), Yb5-xMgxGe4 (x approximately 1). Crystal data for Yb4.04(1)Mg0.96(1)Ge4 at 23 degrees C: orthorhombic, space group Pnma (No. 62), Z = 4; a = 7.155(2) A, b = 14.769(5) A, c = 7.688(2) A; V = 812.5(4) A3. This phase is an example of a substitution of lanthanide metal (Yb) with a nonmagnetic element (Mg) within this structure type. Its structure can alternatively be described as an intergrowth of the hypothetical Yb2MgGe2, which features flat infinite [MgGe2]4- layers and the hypothetical YbGe with [Ge2]6- dimers. The flat [MgGe2]4- layers propagate in two dimensions (a and c), and they are offset by a distance of 1/4.a with respect to one another and are interspaced with layers of [Ge2]6- dimers and Yb cations filling the space between them. According to the structural and physical property data, Yb4MgGe4 is a heterogeneous mixed-valent compound, i.e. a system where one of the two symmetry-inequivalent Yb sites has atoms in closed-shell Yb2+ configuration, whereas the Yb3+ cations occupy a different crystallographic site.

  1. Synthesis, crystal structure, and magnetism of A2Co12As7 (A=Ca, Y, Ce–Yb)

    DOE PAGES

    Tan, Xiaoyan; Ovidiu Garlea, V.; Chai, Ping; Geondzhian, Andrey Y.; Yaroslavtsev, Alexander A.; Xin, Yan; Menushenkov, Alexey P.; Chernikov, Roman V.; Shatruk, Michael

    2015-08-28

    In this study, ternary intermetallics, A2Co12As7 (A=Ca, Y, Ce–Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the Zr2Fe12P7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior ofmore » A2Co12As7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100–140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr–Sm to ferromagnetic for A=Ce and Eu–Yb. Finally, polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce2Co12As7 and Nd2Co12As7, respectively.« less

  2. Phase equilibrium and intermediate phases in the Eu-Sb system

    SciTech Connect

    Abdusalyamova, M.N.

    2011-10-15

    Rapid heating rate thermal analysis, X-ray diffraction, fluorescence spectrometry, and differential dissolution method were used to study the high-temperature phase equilibrium in the Eu-Sb system within the composition range between 37 and 96 at% Sb. The techniques were effective in determination of the vapor-solid-liquid equilibrium since intermediate phases except Eu{sub 4}Sb{sub 3} evaporated incongruently after melting. A thermal procedure was developed to determine the liquidus and solidus lines of the T-x diagram. Six stable phases were identified: two phases, EuSb{sub 2} and Eu{sub 4}Sb{sub 3}, melt congruently at 1045{+-}10 deg. C and 1600{+-}15 deg. C, the Eu{sub 2}Sb{sub 3}, Eu{sub 11}Sb{sub 10}, Eu{sub 5}Sb{sub 4}, and Eu{sub 5}Sb{sub 3} phases melt incongruently at 850{+-}8 deg. C, 950{+-}10 deg. C, 1350{+-}15 deg. C, and 1445{+-}15 deg. C, respectively. The exact composition shifting of Sb-rich decomposable phases towards Eu{sub 4}Sb{sub 3}, the most refractory compound, was determined. The topology of the Eu-Sb phase diagram was considered together with that of the Yb-Sb system. - Graphical abstract: The high-temperature range of the T-x phase diagram for the Eu-Sb system. Highlights: > The phase relations in the Eu-Sb system were studied over a large composition and temperature scale. > The liquidus and solidus lines of the T-x diagram were well established using effective techniques. > In the system, six binary phases are stable and they melt incongruently except EuSb{sub 2} and Eu{sub 4}Sb{sub 3}. > Incongruent evaporation was found to be typical of all the phases besides Eu{sub 4}Sb{sub 3}.

  3. CaF2:Yb laser ceramics

    NASA Astrophysics Data System (ADS)

    Akchurin, M. Sh.; Basiev, T. T.; Demidenko, A. A.; Doroshenko, M. E.; Fedorov, P. P.; Garibin, E. A.; Gusev, P. E.; Kuznetsov, S. V.; Krutov, M. A.; Mironov, I. A.; Osiko, V. V.; Popov, P. A.

    2013-01-01

    CaF2:Yb fluoride laser ceramics, prepared by hot-forming, exhibit the same optical properties as starting single crystals. Slope efficiency of the Сa0.95Yb0.05F2.05 is equal to 35% in the pulsed mode of laser operation. Decrease of ytterbium concentration in CaF2:Yb samples down to 3 mol.% resulted in the essential improvement of Сa0.97Yb0.03F2.03 thermal conductivity from 3.5 to 4.5 W/m K, but slightly decreased (down to 30%) slope efficiency of the samples under both pulsed and CW mode of operation. Alternative hot-pressing synthesis of CaF2:Yb fluoride laser ceramics provided materials with superior mechanical properties (microhardness Н = 3.2 GPa and fracture toughness К1С = 0.65 МPа m1/2) in comparison with hot-formed and/or single crystal CaF2:Yb specimens. For the first time, lasing has been observed for the novel aforementioned hot-pressed CaF2:Yb ceramics.

  4. Unconventional T-H Phase Diagram in the Noncentrosymmetric Compound Yb2Fe12P7

    NASA Astrophysics Data System (ADS)

    Baumbach, R. E.; Hamlin, J. J.; Shu, L.; Zocco, D. A.; O'Brien, J. R.; Ho, P.-C.; Maple, M. B.

    2010-09-01

    The temperature-(T-)magnetic-field (H) phase diagram for the noncentrosymmetric compound YbFeP, determined from electrical resistivity (ρ), specific heat (C), and magnetization (M) measurements on single crystal specimens, is reported. This system exhibits a crossover from a magnetically ordered non-Fermi-liquid (NFL) phase at low H to another NFL phase at higher H. The crossover occurs near the value of H where the magnetic ordering temperature (TM) is no longer observable in C(T,H)/T and ρ(T,H), but not where TM extrapolates smoothly to T=0K at a possible quantum critical point (QCP). This indicates the occurrence of a quantum phase transition between the two NFL phases. The lack of a clear relationship between the extrapolated QCP and NFL behavior suggests an unconventional route to the NFL ground states.

  5. Collapse dynamics of a {sup 176}Yb-{sup 174}Yb Bose-Einstein condensate

    SciTech Connect

    Chaudhary, G. K.; Ramakumar, R.

    2010-06-15

    In this paper, we present a theoretical study of a two-component Bose-Einstein condensate composed of ytterbium (Yb) isotopes in a three-dimensional anisotropic harmonic potential. The condensate consists of a mixture of {sup 176}Yb atoms which have a negative s-wave scattering length and {sup 174}Yb atoms having a positive s-wave scattering length. We study the ground-state as well as dynamic properties of this two-component condensate. Due to the attractive interactions between {sup 176}Yb atoms, the condensate of {sup 176}Yb undergoes a collapse when the particle number exceeds a critical value. The critical number and the collapse dynamics are modified due to the presence of {sup 174}Yb atoms. We use coupled two-component Gross-Pitaevskii equations to study the collapse dynamics. The theoretical results obtained are in reasonable agreement with the experimental results of Fukuhara et al. [Phys. Rev. A 79, 021601(R) (2009)].

  6. Anomalies in the Young modulus at structural phase transitions in rare-earth cobaltites RBaCo{sub 4}O{sub 7} (R = Y, Tm-Lu)

    SciTech Connect

    Kazei, Z. A. Snegirev, V. V.; Andreenko, A. S.; Kozeeva, L. P.

    2011-08-15

    The elastic properties of rare-earth cobaltites RBaCo{sub 4}O{sub 7} (R = Y, Tm-Lu) have been experimentally studied in the temperature range of 80-300 K. The strong softening of the Young modulus {Delta}E(T)/E{sub 0} Almost-Equal-To -(0.1-0.2) of cobaltites with Lu and Yb ions has been revealed, which is due to the instability of the crystal structure upon cooling and is accompanied by an inverse jump at the second-order structural phase transition. The softening of the Young modulus and the jump at the phase transition decrease by an order of magnitude and the transition temperature T{sub s} and hysteresis {Delta}T{sub s} increase from a compound with Lu to that with Tm. A large softening of the Young modulus at the structural transition in Lu- and Yb cobaltites indicates that the corresponding elastic constant goes to zero, whereas this constant in Tm cobaltite is not a 'soft' mode of the phase transition. It has been found that the structural phase transition in Lu- and Yb cobaltites is accompanied by a large absorption maximum at the phase transition point and an additional maximum in the low-temperature phase and absorption anomalies in Tm cobaltite is an order of magnitude smaller.

  7. Monodisperse lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm): morphology controlled synthesis, up-conversion luminescence and in vitro cell imaging

    NASA Astrophysics Data System (ADS)

    Zhang, Yang; Li, Xuejiao; Hou, Zhiyao; Lin, Jun

    2014-05-01

    Lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm) nano/micro-materials with a variety of well-defined morphologies including nanorods, nanospindles, nanorod-bundles and nanospheres, have been successfully synthesized via a facile precipitation technique followed by a heating treatment. It is found that the pH values, fluoride sources and dosage of urea in the initial reaction systems play critical roles in the morphology determination of the LnOF products and the possible formation mechanism for these diverse architectures has been presented. XRD, FT-IR, TG-DTA, SEM, TEM, as well as up-conversion (UC) luminescence spectra are used to characterize the synthesized samples. Under 980 nm NIR laser excitation, red, green and blue UC luminescence are observed from Yb3+/Er3+, Yb3+/Ho3+ and Yb3+/Tm3+ co-doped YOF nanospheres. The MTT assay indicates that YOF nanospheres exhibit good biocompatibility. Especially, the emission spectrum of YOF: 0.20Yb3+, 0.04Er3+ nanospheres is dominated by a single red emission at 660 nm, which falls into the ``optical window'' of biological tissues. The application of YOF: 0.20Yb3+, 0.04Er3+ nanospheres in the cell imaging is also investigated, which shows a bright-red emission without background noise.Lanthanide oxyfluorides LnOF (Ln = Y, La, Pr-Tm) nano/micro-materials with a variety of well-defined morphologies including nanorods, nanospindles, nanorod-bundles and nanospheres, have been successfully synthesized via a facile precipitation technique followed by a heating treatment. It is found that the pH values, fluoride sources and dosage of urea in the initial reaction systems play critical roles in the morphology determination of the LnOF products and the possible formation mechanism for these diverse architectures has been presented. XRD, FT-IR, TG-DTA, SEM, TEM, as well as up-conversion (UC) luminescence spectra are used to characterize the synthesized samples. Under 980 nm NIR laser excitation, red, green and blue UC luminescence are

  8. Visualization of 2-μm radiation by BiF3:Ho3+ and BiF3:Ho3+/Yb3+ ceramics

    NASA Astrophysics Data System (ADS)

    Savikin, A. P.; Egorov, A. S.; Budruev, A. V.; Grishin, I. A.

    2016-06-01

    A series of ceramic samples of the compositions BiF3:1%Ho3+, BiF3:4%Ho3+, BiF3:1%Ho3+ + 1%Yb3+, and BiF3:1%Ho3+ + 3%Yb3+ is synthesized and the conversion of Tm:YLF laser radiation (λ = 1908 nm) is studied. The luminescence spectra exhibit bands in the regions of 490, 545, and 650 nm. The kinetic measurements of the afterglow of the green and red bands show that the population of the 5 S 2 and 5 F 4 states in the BiF3:1%Ho3+ samples occurs due to successive absorption of excitation photons, while the 5 F 5 level of Ho3+ is populated due to the ion-ion interaction. Codoping with Yb3+ leads to a decrease in the visualization threshold power density to 2 W/cm2.

  9. The peculiarities of local structure of YbNi2 and YbCo2 intermetallics synthesized at high pressure.

    NASA Astrophysics Data System (ADS)

    Chernysheva, O. V.; Menushenkov, A. P.; Tsvyashchenko, A. V.; Fomicheva, L. N.; Ivanov, A. A.; Kuznetsov, A. V.

    2016-09-01

    Local structure of YbCo2 and YbNi2 was investigated by EXAFS and XANES spectroscopy. It was found that the bond Yb-Co(Ni) has the highest static disorder and its length increases with temperature decrease, while all other bonds remain almost unchanged. This phenomenon may be caused by short-range magnetic ordering at temperatures above the phase transition. XANES measurements above ZIII-Yb absorption edge in YbCo2 and YbNi2 revealed that both compounds have almost the same density of free 5d-states

  10. Listening and Legos[TM

    ERIC Educational Resources Information Center

    Morris, Pamela

    2012-01-01

    This simple exercise, performed in teams, gives students practice in listening to instructions, particularly when there are restrictions for the communication. The teams compete in a limited amount of time to build a Lego[TM] structure based on the instructions of one team member. Which team listens the best and is most successful?

  11. 75 FR 5068 - Lock + TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-01

    ... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Lock + \\TM\\ Hydro Friends Fund XXXIII, LLC; Notice of Preliminary Permit Application Accepted for Filing and Soliciting Comments, Motions To Intervene, and Competing Applications January 22, 2010. On January 8,...

  12. 75 FR 5071 - Lock + TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-02-01

    ..., Chairman and CEO, Hydro Green Energy, LLC., 5090 Richmond Avenue, Suite 290, Houston, TX 77056, (877) 556... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Lock + \\TM\\ Hydro Friends Fund XXXI, LLC; Notice of Preliminary...

  13. Group delay dispersion measurement of Yb:Gd(2)SiO(5), Yb:GdYSiO(5) and Yb:LuYSiO(5)crystal with white-light interferometry.

    PubMed

    Yang, Weijian; Li, Jing; Zhang, Fan; Zhang, Yuanyang; Zhang, Zhigang; Zhao, Guangjun; Zheng, Lihe; Xu, Jun; Su, Liangbi

    2007-06-25

    We report the measured group delay dispersion (GDD) of new crystals Yb:Gd(2)SiO,(5)(Yb:GSO), Yb:GdYSiO(5) (Yb:GYSO) and Yb:LuYSiO(5) (Yb:LYSO) over wavelengths from 1000nm to 1200nm, with a white-light interferometer. Those GDD data should be useful for the dispersion compensation for femtosecond pulse generation in the lasers with these new crystals as the gain media.

  14. Modified LaRC(TM)-IA Polyimides

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Chang, Alice C.; Hou, Tan H.; Working, Dennis C.

    1994-01-01

    Modified versions of thermoplastic polyimide LaRC(TM)-IA incorporate various amounts of additional, rigid moieties into backbones of LaRC(TM)-IA molecules. Modified versions more resistant to solvents and exhibit higher glass-transition temperatures, yet retain melt-flow processability of unmodified LaRC(TM)-IA.

  15. 75 FR 2129 - Lock+TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-01-14

    ... Energy Regulatory Commission Lock+ TM Hydro Friends Fund XXX, LLC; Notice of Preliminary Permit... January 6, 2010. On November 13, 2009, Lock+ TM Hydro Friends Fund XXX, LLC filed an application, pursuant...,018 megawatt-hours. Applicant Contact: Wayne F. Krouse, Lock+ TM Hydro Friends Fund XXX, LLC,...

  16. Cryogenically-cooled Yb:YGAG ceramic picosecond oscillator

    NASA Astrophysics Data System (ADS)

    Mužik, J.; Jelínek, M.; Miura, T.; Smrž, M.; Endo, A.; Mocek, T.; Kubeček, V.

    2016-04-01

    In this work, a passively mode-locked Yb:YGAG (Yb:Y3Ga2Al3O12) ceramic laser generating picosecond pulses at liquid-nitrogen temperature is demonstrated. The Yb:YGAG has a similar structure to Yb:YAG, but its emission bandwidth at cryogenic temperature remains much broader, which is advantageous for ultrashort pulse generation and amplification. Using this laser material, a stable train of pulses at a wavelength of 1026 nm was obtained, with measured pulse duration of 2.4 ps, which is more than four times shorter than that achieved with a cryogenically-cooled Yb:YAG.

  17. Evidence from Tm anomalies for non-CI refractory lithophile element proportions in terrestrial planets and achondrites

    NASA Astrophysics Data System (ADS)

    Barrat, J. A.; Dauphas, N.; Gillet, P.; Bollinger, C.; Etoubleau, J.; Bischoff, A.; Yamaguchi, A.

    2016-03-01

    Thulium is a heavy rare earth element (REE) whose geochemical behavior is intermediate between Er and Yb, and that is not expected to be decoupled from these elements during accretion of planetary bodies and geological processes. However, irregularities in REE volatilities at higher temperature could have decoupled the REEs relative to one another during the early stages of condensation of the solar nebula. Indeed, positive Tm anomalies are found in some refractory inclusions from carbonaceous chondrites, and it is possible that large scale nebular reservoirs displaying positive or negative Tm anomalies were formed during the early history of the solar system. We analyzed a series of meteorites and terrestrial rocks in order to evaluate the existence of Tm anomalies in planetary materials. Relative to CIs (Ivuna-type carbonaceous chondrites), carbonaceous chondrites display unresolved or positive Tm anomalies, while most of the noncarbonaceous chondrites show slightly negative Tm anomalies. Quantification of these anomalies in terrestrial samples is complicated when samples display fractionated heavy REE patterns. Taking this effect into account, we show that the Earth, Mars, Vesta, the aubrite and ureilite parent bodies display small negative anomalies (Tm/Tm∗ ≈ 0.975), very similar to those found in ordinary and enstatite chondrites. We suggest that a slight negative Tm anomaly relative to CI is a widespread feature of the materials from the inner solar system. This finding suggests that CI chondrites may not be appropriate for normalizing REE abundances of most planetary materials as they may be enriched in a high-temperature refractory component with non-solar composition. The presence of Tm anomalies at a bulk planetary scale is, to this day, the strongest piece of evidence that refractory lithophile elements are not present in constant CI proportions in planetary bodies.

  18. Spectroscopic studies of Yb3+-doped rare earth orthosilicate crystals

    NASA Astrophysics Data System (ADS)

    Campos, S.; Denoyer, A.; Jandl, S.; Viana, B.; Vivien, D.; Loiseau, P.; Ferrand, B.

    2004-06-01

    Infrared transmission and Raman scattering have been used to study Raman active phonons and crystal-field excitations in Yb3+-doped yttrium, lutetium and scandium orthosilicate crystals (Y2SiO5 (YSO), Lu2SiO5 (LSO) and Sc2SiO5 (SSO)), which belong to the same C2h6 crystallographic space group. Energy levels of the Yb3+ ion 2F5/2 manifold are presented. In the three hosts, Yb3+ ions experience high crystal field strength, particularly in Yb:SSO. Satellites in the infrared transmission spectra have been detected for the first time in the Yb3+-doped rare earth orthosilicates. They could be attributed to perturbed Yb3+ sites of the lattices or to magnetically coupled Yb3+ pairs.

  19. The tmRNA ribosome rescue system

    PubMed Central

    Janssen, Brian D.; Hayes, Christopher S.

    2012-01-01

    The bacterial tmRNA quality control system monitors protein synthesis and recycles stalled translation complexes in a process termed “ribosome rescue”. During rescue, tmRNA acts first as a transfer RNA to bind stalled ribosomes, then as a messenger RNA to add the ssrA peptide tag to the C-terminus of the nascent polypeptide chain. The ssrA peptide targets tagged peptides for proteolysis, ensuring rapid degradation of potentially deleterious truncated polypeptides. Ribosome rescue also facilitates turnover of the damaged messages responsible for translational arrest. Thus, tmRNA increases the fidelity of gene expression by promoting the synthesis of full-length proteins. In addition to serving as a global quality control system, tmRNA also plays important roles in bacterial development, pathogenesis and environmental stress responses. This review focuses on the mechanism of tmRNA-mediated ribosome rescue and the role of tmRNA in bacterial physiology. PMID:22243584

  20. Magnetization and transport properties of single crystalline RPd2P2 (R=Y, La-Nd, Sm-Ho, Yb)

    NASA Astrophysics Data System (ADS)

    Drachuck, Gil; Böhmer, Anna E.; Bud'ko, Sergey L.; Canfield, Paul C.

    2016-11-01

    Single crystals of RPd2P2 (R=Y, La-Nd, Sm-Ho, Yb) were grown out of a high temperature solution rich in Pd and P and characterized by room-temperature powder X-ray diffraction, anisotropic temperature- and field-dependent magnetization and temperature-dependent in-plane resistivity measurements. In this series, YPd2P2 and LaPd2P2 YbPd2P2 (with Yb2+) are non-local-moment bearing. Furthermore, YPd2P2 and LaPd2P2 are found to be superconducting with Tc ≃ 0.75 and 0.96 K respectively. CePd2P2 and PrPd2P2 magnetically order at low temperature with a ferromagnetic component along the crystallographic c-axis. The rest of the series manifest low temperature antiferromagnetic ordering. EuPd2P2 has Eu2+ ions and both EuPd2P2 and GdPd2P2 have isotropic paramagnetic susceptibilities consistent with L=0 and J = S = 7/2 and exhibit multiple magnetic transitions. For R=Eu-Dy, there are multiple, T > 1.8 K transitions in zero applied magnetic field and for R=Nd, Eu, Gd, Tb, and Dy there are clear metamagnetic transitions at T=2.0 K for H < 55 kOe. Strong anisotropies arising mostly from crystal electric field (CEF) effects were observed for most magnetic rare earths with L ≠ 0. The experimentally estimated CEF parameters B20 were calculated from the anisotropic paramagnetic θab and θc values and compared to theoretical trends across the rare earth series. The ordering temperatures as well as the polycrystalline averaged paramagnetic Curie-Weiss temperature, θave, were extracted from magnetization and resistivity measurements, and compared to the de-Gennes factor.

  1. Dysfunction of Rice Mitochondrial Membrane Induced by Yb3+.

    PubMed

    Gao, Jia-Ling; Wu, Man; Liu, Wen; Feng, Zhi-Jiang; Zhang, Ye-Zhong; Jiang, Feng-Lei; Liu, Yi; Dai, Jie

    2015-12-01

    Ytterbium (Yb), a widely used rare earth element, is treated as highly toxic to human being and adverseness to plant. Mitochondria play a significant role in plant growth and development, and are proposed as a potential target for ytterbium toxicity. In this paper, the biological effect of Yb(3+) on isolated rice mitochondria was investigated. We found that Yb(3+) with high concentrations (200 ~ 600 μM) not only induced mitochondrial membrane permeability transition (mtMPT), but also disturbed the mitochondrial ultrastructure. Moreover, Yb(3+) caused the respiratory chain damage, ROS formation, membrane potential decrease, and mitochondrial complex II activity reverse. The results above suggested that Yb(3+) with high concentrations could induce mitochondrial membrane dysfunction. These findings will support some valuable information to the safe application of Yb-based agents. PMID:26305923

  2. Magnetic properties of EuLn{sub 2}O{sub 4} (Ln=rare earths)

    SciTech Connect

    Hirose, Keiichi; Doi, Yoshihiro; Hinatsu, Yukio

    2009-07-15

    Ternary rare earth oxides EuLn{sub 2}O{sub 4} (Ln=Gd, Dy-Lu) were prepared. They crystallized in an orthorhombic CaFe{sub 2}O{sub 4}-type structure with space group Pnma. {sup 151}Eu Moessbauer spectroscopic measurements show that the Eu ions are in the divalent state. All these compounds show an antiferromagnetic transition at 4.2-6.3 K. From the positive Weiss constant and the saturation of magnetization for EuLu{sub 2}O{sub 4}, it is considered that ferromagnetic chains of Eu{sup 2+} are aligned along the b-axis of the orthorhombic unit cell, with neighboring Eu{sup 2+} chains antiparallel. When Ln=Gd-Tm, ferromagnetically aligned Eu{sup 2+} ions interact with the Ln{sup 3+} ions, which would overcome the magnetic frustration of triangularly aligned Ln{sup 3+} ions and the EuLn{sub 2}O{sub 4} compounds show a simple antiferromagnetic behavior. - Graphical abstract: Ternary rare earth oxides EuLn{sub 2}O{sub 4} (Ln=Gd, Dy-Lu) crystallized in an orthorhombic CaFe{sub 2}O{sub 4}-type structure with space group Pnma. Moessbauer spectroscopic measurements show that the Eu ions are in the divalent state. All these compounds show an antiferromagnetic transition at 4.2-6.3 K. It is considered that ferromagnetic chains of Eu{sup 2+} are aligned along the b-axis of the orthorhombic unit cell, with neighboring Eu{sup 2+} chains antiparallel.

  3. Scaling of Yb-Fiber Frequency Combs

    NASA Astrophysics Data System (ADS)

    Ruehl, Axel; Marcinkevicius, Andrius; Fermann, Martin E.; Hartl, Ingmar

    2010-06-01

    Immediately after their introduction in 1999, femtosecond laser frequency combs revolutionized the field of precision optical frequency metrology and are key elements in many experiments. Frequency combs based on femtosecond Er-fiber lasers based were demonstrated in 2005, allowing additionally rugged, compact set-ups and reliable unattended long-term operation. The introduction of Yb-fiber technology led to an dramatic improvement in fiber-comb performance in various aspects. Low-noise Yb-fiber femtosecond oscillators enabled a reduction of relative comb tooth linewidth to the sub-Hz level as well as scaling of the fundamental comb spacings up to 1 GHz. This is beneficial for any frequency-domain comb application due to the higher power per comb-mode. Many spectroscopic applications require, however, frequency combs way beyond the wavelength range accessible with broad band laser materials, so nonlinear conversion and hence higher peak intensity is required. We demonstrated power scaling of Yb-fiber frequency combs up to 80 W average power in a strictly linear chirped-pulse amplification schemes compatible with low-noise phase control. These high-power Yb-fiber-frequency combs facilitated not only the extension to the mid-IR spectral region. When coupled to a passive enhancement cavity, the average power can be further scaled to the kW-level opening new capabilities for XUV frequency combs via high-harmonic generation. All these advances of fiber-based frequency combs will trigger many novel applications both in fundamental and applied sciences. Schibli et al., Nature Photonics 2 355 (2008). Hartl et al., MF9 in Advanced Solid-State Photonics. 2009, Optical Society of America. Ruehl et al., AWC7 in Advanced Solid-State Photonics. 2010, Optical Society of America. Adler et al., Optics Letters 34 1330 (2009). Yost et al., Nature Physics 5 815 (2009).

  4. Melt processing of Yb-123 tapes

    SciTech Connect

    Athur, S. P.; Balachandran, U.; Salama, K.

    2000-02-17

    The innovation of a simple, scalable process for manufacturing long-length conductors of HTS is essential to potential commercial applications such as power cables, magnets, and transformers. In this paper the authors demonstrate that melt processing of Yb-123 tapes made by the PIT route is an alternative to the coated conductor and Bi-2223 PIT tape fabrication techniques. Ag-clad Yb-123 tapes were fabricated by groove rolling and subsequently, melt processed in different oxygen partial pressures in a zone-melting furnace with a gradient of 140 C/cm. The transition temperatures measured were found to be around 81 K undermost processing conditions. EPMA of the tapes processed under different conditions show the 123 phase to be Ba deficient and Cu and Yb rich. Critical current was measured at various temperatures from 77 K to 4.2 K. The J{sub c} increased with decrease in pO{sub 2}. The highest I{sub c} obtained was 52 A at 4.2 K.

  5. YB-1 protein: functions and regulation.

    PubMed

    Lyabin, Dmitry N; Eliseeva, Irina A; Ovchinnikov, Lev P

    2014-01-01

    The Y-box binding protein 1 (YB-1, YBX1) is a member of the family of DNA- and RNA-binding proteins with an evolutionarily ancient and conserved cold shock domain. It falls into a group of intrinsically disordered proteins that do not follow the classical rule 'one protein-one function' but introduce a novel principle stating that a disordered structure suggests many functions. YB-1 participates in a wide variety of DNA/RNA-dependent events, including DNA reparation, pre-mRNA transcription and splicing, mRNA packaging, and regulation of mRNA stability and translation. At the cell level, the multiple activities of YB-1 are manifested as its involvement in cell proliferation and differentiation, stress response, and malignant cell transformation. WIREs RNA 2014, 5:95-110. doi: 10.1002/wrna.1200 CONFLICT OF INTEREST: The authors have declared no conflicts of interest for this article. For further resources related to this article, please visit the WIREs website.

  6. Yb doping concentration and temperature influence on Yb:LuAG thermal lensing

    NASA Astrophysics Data System (ADS)

    Veselský, Karel; Šulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Škoda, Václav

    2016-03-01

    The aim of this study was to investigate whether refractive power of thermal lens for Yb:LuAG crystal at cryogenic temperatures depends on Yb doping concentration which has not been examined yet. The three measured Yb:LuAG laser rods samples (length of 3 mm, diameter 3 mm, AR @ 0.94 μm and 1.03 μm, doping concentration 5.4, 8.4 and 16.6 at. % Yb/Lu) were mounted in the temperature controlled copper holder of the liquid nitrogen cryostat. Samples were longitudinally pumped with fiber coupled CW laser diode at 0.930 μm with the focal point 0.4 mm in diameter. The 38 mm long semi-hemispherical laser resonator consisted of a flat pump mirror (HR @ 1.03 μm and HT 0.94 μm) and curved output coupler (r=500 mm) of reflectivity 94 % @ 1.06 μm. The refractive power of thermal lens was estimated indirectly by measuring of change in the position of focused laser beam focal point. The measurement was performed for constant absorbed power of 10 W in temperature range from 80 up to 240 K. It was observed that cryogenic cooling caused reduction of thermal lens power, which increased linearly with increasing temperature. For temperatures from 80 to 160 K refractive power was identical for all concentration. For higher temperature the refractive power of thermal lens increased with increasing Yb3+ concentration. Presented study shows that application of cryogenic temperature leads to reduction of thermal effect even for high dopant concentration in Yb:LuAG crystal. This is essential for reaching of high output power while maintaining high beam quality.

  7. Monodisperse and core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} (Ln=Eu, Tb, Dy, Sm, Er, Ho, and Tm) spherical particles: A facile synthesis and luminescent properties

    SciTech Connect

    Xu, Zhenhe; Feng, Bin; Bian, Shasha; Liu, Tao; Wang, Mingli; Gao, Yu; Sun, Di; Gao, Xin; Sun, Yaguang

    2012-12-15

    The core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles were realized by coating the Lu{sub 2}O{sub 3}:Ln{sup 3+} phosphors onto the surface of non-aggregated, monodisperse and spherical SiO{sub 2} particles by the Pechini sol-gel method. The as-synthesized products were characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), energy-dispersive X-ray (EDX) spectra, scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), photolumiminescence (PL), and low-voltage cathodoluminescence (CL). The results indicate that the 800 Degree-Sign C annealed sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores, in spherical shape with a narrow size distribution. The as-obtained particles show strong light emission with different colors corresponding to different Ln{sup 3+} ions under ultraviolet-visible light excitation and low-voltage electron beams excitation, which have potential applications in fluorescent lamps and field emission displays. - Graphical Abstract: Representative SEM and TEM images of the core-shell structured SiO{sub 2}-Lu{sub 2}O{sub 3}:Eu{sup 3+} particles; CIE chromaticity diagram showing the emission colors for SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+}; Multicolor emissions of SiO{sub 2}-Lu{sub 2}O{sub 3}:Ln{sup 3+} particles. Highlights: Black-Right-Pointing-Pointer The core-shell particles were realized by coating the phosphors onto the surface of SiO{sub 2} particles. Black-Right-Pointing-Pointer The sample consists of crystalline Lu{sub 2}O{sub 3} shells and amorphous SiO{sub 2} cores. Black-Right-Pointing-Pointer The particles show different light emission colors corresponding to Ln{sup 3+} ions. Black-Right-Pointing-Pointer They have potential applications in fluorescent lamps and field emission displays.

  8. ERIC/TM--A Growing Resource.

    ERIC Educational Resources Information Center

    Rudner, Lawrence M.; Wise, Lauress L.

    The Educational Resources Information Center (ERIC) is one of the major bibliographic databases in the world. The ERIC Clearinghouse on Tests, Measurement, and Evaluation (ERIC/TM) contributes to this database by acquiring, selecting, and processing documents pertaining to all aspects of testing, evaluation, and learning theory. The ERIC/TM has…

  9. A Review of "Integrity[TM]"

    ERIC Educational Resources Information Center

    Veldkamp, Bernard P.

    2008-01-01

    Integrity[TM], an online application for testing both the statistical integrity of the test and the academic integrity of the examinees, was evaluated for this review. Program features and the program output are described. An overview of the statistics in Integrity[TM] is provided, and the application is illustrated with a small simulation study.…

  10. Transmission electron microscopy study of the MgS–Tm{sub 2}S{sub 3} system

    SciTech Connect

    Varadé-López, R.; Ávila-Brande, D.; Urones-Garrote, E.; Otero-Díaz, L.C.

    2015-09-15

    This work presents the structural–microstructural characterization of the NaCl-derivative MgS–Tm{sub 2}S{sub 3} system, which can be formulated by the expression Mg{sub (1−x)}Tm{sub (2/3)x}□{sub (1/3)x}S (□→cation vacancy). Transmission electron microscopy observations show the transition between NaCl-type and spinel-type structures when 0 ≤x≤ 0.75. The increase of Tm content in the solid solution provokes the increase of the spinel-type phase proportion, which intergrows with the NaCl-type crystals. When x≥0.75, some phases derived from NaCl-type structure through the chemical twinning at the unit cell level crystallographic operation are observed, such as CT-MgTm{sub 2}S{sub 4} and CT-MgTm{sub 4}S{sub 7}. The existence and nature of the extended defects observed along the c direction of these structures are characterized by means of Scanning-Transmission electron microscopy high-angle dark field imaging, which allows observing the presence of quasi ordered crystals with new possible complex stoichiometries at atomic resolution. - Graphical abstract: HAADF-STEM image of a disordered CT-MgYb{sub 2}S{sub 4} crystal. The disordered twin-slab sequences are marked by arrows. - Highlights: • Structural evolution of the Mg{sub (1−x)}Tm{sub (2/3)x}□{sub (1/3)x}S system was characterized by means of TEM. • The increase in Tm content provokes the transition from NaCl to spinel-type structure up to x=0.75. • Chemical twinned phases CT-MgTm{sub 2}S{sub 4} and CT-MgTm{sub 4}S{sub 7} are observed at high Tm contents. • Extended defects in CT-crystals are characterized with atomic resolution STEM-HAADF images.

  11. Constitutive and functional expression of YB-1 in microglial cells.

    PubMed

    Keilhoff, G; Titze, M; Esser, T; Langnaese, K; Ebmeyer, U

    2015-08-20

    Y-box-binding protein (YB-1) is a member of the cold-shock protein family and participates in a wide variety of DNA/RNA-dependent cellular processes including DNA repair, transcription, mRNA splicing, packaging, and translation. At the cellular level, YB-1 is involved in cell proliferation and differentiation, stress responses, and malignant cell transformation. A general role for YB-1 during inflammation has also been well described; however, there are minimal data concerning YB-1 expression in microglia, which are the immune cells of the brain. Therefore, we studied the expression of YB-1 in a clinically relevant global ischemia model for neurological injury following cardiac arrest. This model is characterized by massive neurodegeneration of the hippocampal CA1 region and the subsequent long-lasting activation of microglia. In addition, we studied YB-1 expression in BV-2 cells, which are an accepted microglia culture model. BV-2 cells were stressed by oxygen/glucose deprivation (OGD), OGD-relevant mediators, lipopolysaccharide (LPS), and phagocytosis-inducing cell debris and nanoparticles. Using quantitative polymerase chain reaction (PCR), we show constitutive expression of YB-1 transcripts in unstressed BV-2 cells. The functional upregulation of the YB-1 protein was demonstrated in microglia in vivo and in BV-2 cells in vitro. All stressors except for LPS were potent enhancers of the level of YB-1 protein, which appears to be regulated primarily by proteasomal degradation and, to a lesser extent, by the activation (phosphorylation) of the translation initiation factor eIF4E. The proteasome of BV-2 cells is impaired by OGD, which results in decreased protein degradation and therefore increased levels of YB-1 protein. LPS induces proteasome activity, which enables the level of YB-1 protein to remain at control levels despite enhanced protein ubiquitination. The proteasome inhibitor MG-132 was able to increase YB-1 protein levels in control and LPS

  12. Thermodynamics of the hydration equilibrium derived from the luminescence spectra of the solid state for the case of the Eu-EDTA system.

    PubMed

    Janicki, R; Mondry, A

    2015-11-28

    The luminescence properties of two compounds, [C(NH2)3][Eu(EDTA)(H2O)3] (I) and [C(NH2)3]2[Yb0.97Eu0.03(EDTA)(H2O)2]ClO4·6H2O (II), were determined. The weighted sum of luminescence spectra of I and II was used to reproduce the spectra of the Eu-EDTA system in aqueous solution in the temperature range 276-363 K. By implementing this method it was possible to determine the thermodynamic functions (ΔH = 18113 ± 506 J mole(-1) and ΔS = 62.5 ± 4.9 J mole(-1) K(-1)) of the reaction [Eu(EDTA)(H2O)3](-)⇆ [Eu(EDTA)(H2O)2](-) + H2O, which is difficult using other methods.

  13. Anisotropic magnetization and transport properties of RAgSb{sub 2} (R=Y, La-Nd, Sm, Gd-Tm)

    SciTech Connect

    Myers, Kenneth D.

    1999-11-08

    This study of the RAgSb{sub 2} series of compounds arose as part of an investigation of rare earth intermetallic compounds containing antimony with the rare earth in a position with tetragonal point symmetry. Materials with the rare earth in a position with tetragonal point symmetry frequently manifest strong anisotropies and rich complexity in the magnetic properties, and yet are simple enough to analyze. Antimony containing intermetallic compounds commonly possess low carrier densities and have only recently been the subject of study. Large single grain crystals were grown of the RAgSb{sub 2} (R=Y, La-Nd, Sm, Gd-Tm) series of compounds out of a high temperature solution. This method of crystal growth, commonly known as flux growth is a versatile method which takes advantage of the decreasing solubility of the target compound with decreasing temperature. Overall, the results of the crystal growth were impressive with the synthesis of single crystals of LaAgSb{sub 2} approaching one gram. However, the sample yield diminishes as the rare earth elements become smaller and heavier. Consequently, no crystals could be grown with R=Yb or Lu. Furthermore, EuAgSb{sub 2} could not be synthesized, likely due to the divalency of the Eu ion. For most of the RAgSb{sub 2} compounds, strong magnetic anisotropies are created by the crystal electric field splitting of the Hund's rule ground state. This splitting confines the local moments to lie in the basal plane (easy plane) for the majority of the members of the series. Exceptions to this include ErAgSb{sub 2} and TmAgSb{sub 2}, which have moments along the c-axis (easy axis) and CeAgSb{sub 2}, which at intermediate temperatures has an easy plane, but exchange coupling at low temperatures is anisotropic with an easy axis. Additional anisotropy is also observed within the basal plane of DyAgSb{sub 2}, where the moments are restricted to align along one of the {l_angle}110{r_angle} axes. Most of the RAgSb{sub 2} compounds

  14. From stable divalent to valence-fluctuating behaviour in Eu(Rh(1-x)Ir(x))2Si2 single crystals.

    PubMed

    Seiro, Silvia; Geibel, Christoph

    2011-09-21

    We have succeeded in growing high-quality single crystals of the valence-fluctuating system EuIr(2)Si(2), the divalent Eu system EuRh(2)Si(2) and the substitutional alloy Eu(Rh(1-x)Ir(x))(2)Si(2) across the range 0 < x < 1, which we characterized by means of x-ray diffraction, energy-dispersive x-ray spectroscopy, specific heat, magnetization and resistivity measurements. On increasing x, the divalent Eu ground state subsists up to x = 0.25 with a slight increase in Néel temperature, while for 0.3≤x < 0.7 a sharp hysteretic change in susceptibility and resistivity marks the first-order valence transition. For x≳0.7 the broad feature observed in the physical properties is characteristic of the continuous valence evolution beyond the critical end point of the valence transition line, and the resistivity is reminiscent of Kondo-like behaviour while the Sommerfeld coefficient indicates a mass renormalization of at least a factor of 8. The resulting phase diagram is similar to those reported for polycrystalline Eu(Pd(1-x)Au(x))(2)Si(2) and EuNi(2)(Si(1-x)Ge(x))(2), confirming its generic character for Eu systems, and markedly different to those of homologue Ce and Yb systems, which present a continuous suppression of the antiferromagnetism accompanied by a very smooth evolution of the valence. We discuss these differences and suggest them to be related to the large polarization energy of the Eu half-filled 4f shell. We further argue that the changes in the rare earth valence between RRh(2)Si(2) and RIr(2)Si(2) (R = Ce, Eu, Yb) are governed by a purely electronic effect and not by a volume effect.

  15. Structural, morphological and spectroscopic properties of Eu{sup 3+}-doped rare earth fluorides synthesized by the hydrothermalmethod

    SciTech Connect

    Grzyb, Tomasz; Runowski, Marcin; Szczeszak, Agata; Lis, Stefan

    2013-04-15

    Rare earth fluorides (REF{sub 3}, RE=Y, La, Gd or Yb) doped with 5% of Eu{sup 3+} ions were synthesized via the hydrothermal method and their physicochemical properties were compared. The synthesis was carried out in an aqueous medium at elevated pressure and temperature. The reaction was performed in situ, with use of NaBF{sub 4} as a source of fluoride ions. Structural and morphological properties of obtained nanophosphors were characterized with the use of powder X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Synthesized products were nanocrystalline with hexagonal or orthorhombic crystal structures. They showed different morphology, from nanoplates to nanorings, depending on the used REF{sub 3} fluoride as the host for the Eu{sup 3+} ions. The elemental composition was confirmed by the energy-dispersive X-ray spectroscopy (EDX) results. Spectroscopic properties were investigated by measuring the excitation and emission spectra. Also luminescence lifetimes were determined. The synthesized materials showed bright red luminescence, due to the presence of Eu{sup 3+} ions in their structure. - Graphical abstract: Luminescence spectra of the REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd and Yb) fluorides and their TEM images as background. Highlights: ► Nanocrystalline fluorides were synthesized using modified hydrothermal method. ► Structural and morphological properties of in situ prepared nanomaterials were studied. ► Luminescence properties of REF{sub 3}:Eu{sup 3+} (RE=Y, La, Gd, Yb) were compared and investigated.

  16. Growth and spectroscopic properties of Er,Yb : YCOB crystals

    NASA Astrophysics Data System (ADS)

    Yu, Young Moon; Jin Ju, Jung; Cha, Myoungsik

    2001-07-01

    High quality Yb 3+ and Er 3+ co-doped YCa 4O(BO 3) 3 crystals were grown by the Czochralski method. Phase relationships between Y 3+/Yb 3+/Er 3+ and Ca 2+/B 3+ in the vicinity of the stoichiometric composition of YCa 4O(BO 3) 3 were discussed. The calculated absorption and emission cross sections were estimated. Efficient energy transfer from the excited Yb 3+ to the Er 3+ leads to strong emissions in the wavelength range of 1510-1580 nm peaking at 1535 nm. Lifetime of Er- 4I 11/2 was measured to be 1.23 ms. The energy transfer efficiency of 97% for Er 0.02Yb 0.2Y 0.78Ca 4O(BO 3) 3 crystal was estimated from the reduced lifetimes of the Yb 3+- 2F 5/2 level.

  17. Nanosecond cryogenic Yb:YAG disk laser

    SciTech Connect

    Perevezentsev, E A; Mukhin, I B; Kuznetsov, I I; Vadimova, O L; Palashov, O V

    2014-05-30

    A cryogenic Yb:YAG disk laser is modernised to increase its average and peak power. The master oscillator unit of the laser is considerably modified so that the pulse duration decreases to several nanoseconds with the same pulse energy. A cryogenic disk laser head with a flow-through cooling system is developed. Based on two such laser heads, a new main amplifier is assembled according to an active multipass cell scheme. The total small-signal gain of cryogenic cascades is ∼10{sup 8}. (lasers)

  18. Evaluation of 169Yb decay data.

    PubMed

    Bé, Marie-Martine; Schönfeld, Eckart; Morel, Jean

    2002-01-01

    This evaluation of the complete decay scheme of 169Yb sums up the recent measurements carried out during an international exercise in which 11 laboratories were involved, and also takes into account other independent experiments. As a result of the numerous high-quality measurements available, the decay scheme is shown to be highly consistent. The half-life is determined to be 32.018 (5)d, and the emission probabilities of the two reference gamma lines of 198 and 307 keV are recommended to be 35.93 (12)% and 10.046 (45)%, respectively.

  19. Ternary rare earth-lanthanide sulfides. [Re = Eu, Sm or Yb

    DOEpatents

    Takeshita, Takuo; Gschneidner, K.A. Jr.; Beaudry, B.J.

    1986-03-06

    Disclosed is a new ternary rare earth sulfur compound having the formula La/sub 3-x/M/sub x/S/sub 4/, where M is europium, samarium, or ytterbium, with x = 0.15 to 0.8. The compound has good high-temperature thermoelectric properties and exhibits long-term structural stability up to 1000/sup 0/C.

  20. Eu{sub 3}F{sub 4}S{sub 2}: Synthesis, crystal structure, and magnetic properties of the mixed-valent europium(II,III) fluoride sulfide EuF{sub 2}.(EuFS){sub 2}

    SciTech Connect

    Grossholz, Hagen; Hartenbach, Ingo; Kotzyba, Gunter; Poettgen, Rainer; Trill, Henning; Mosel, Bernd D.; Schleid, Thomas

    2009-11-15

    Using the method to synthesize rare-earth metal(III) fluoride sulfides MFS (M=Y, La, Ce-Lu), in some cases we were able to obtain mixed-valent compounds such as Yb{sub 3}F{sub 4}S{sub 2} instead. With Eu{sub 3}F{sub 4}S{sub 2} another isotypic representative has now been synthesized. Eu{sub 3}F{sub 4}S{sub 2} (tetragonal, I4/mmm, a=400.34(2), c=1928.17(9) pm, Z=2) is obtained from the reaction of metallic europium, elemental sulfur, and europium trifluoride in a molar ratio of 5:6:4 within seven days at 850 deg. C in silica-jacketed gas-tightly sealed platinum ampoules. The single-phase product consists of black plate-shaped single crystals with a square cross section, which can be obtained from a flux using equimolar amounts of NaCl as fluxing agent. The crystal structure is best described as an intergrowth structure, in which one layer of CaF{sub 2}-type EuF{sub 2} is followed by two layers of PbFCl-type EuFS when sheeted parallel to the (001) plane. Accordingly there are two chemically and crystallographically different europium cations present. One of them (Eu{sup 2+}) is coordinated by eight fluoride anions in a cubic fashion, the other one (Eu{sup 3+}) exhibits a monocapped square antiprismatic coordination sphere with four F{sup -} and five S{sup 2-} anions. Although the structural ordering of the different charged europium cations is plausible, a certain amount of charge delocalization with some polaron activity has to take place, which is suggested by the black color of the title compound. Temperature dependent magnetic susceptibility measurements of Eu{sub 3}F{sub 4}S{sub 2} show Curie-Weiss behavior with an experimental magnetic moment of 8.19(5) mu{sub B} per formula unit and a paramagnetic Curie temperature of 0.3(2) K. No magnetic ordering is observed down to 4.2 K. In accordance with an ionic formula splitting like (Eu{sup II})(Eu{sup III}){sub 2}F{sub 4}S{sub 2} only one third of the europium centers in Eu{sub 3}F{sub 4}S{sub 2} carry permanent

  1. VentureStar(tm) Payload Processing Concept

    NASA Technical Reports Server (NTRS)

    Sharp, Susan

    1998-01-01

    The philosophy and the operations concept of the VentureStar(tm) payload processing system is presented. The goal of VentureStar(tm) operations is to provide low cost access to space. This is to be achieved through the design of the vehicle, and operability of the ground system. Specifically, this is to be accomplished through rapid turnaround cycles, increased launch rate, high system reliability and availability and reduced required operations personnel. This is presented in viewgraph format.

  2. LaRC(TM)-IA Copolyimides

    NASA Technical Reports Server (NTRS)

    St. Clair, Terry L.; Chang, Alice C.

    1995-01-01

    Copolyimides modified versions of LaRC(TM)-IA thermoplastic polyimide formulated by incorporating moieties of 3,3',4,4'-benzophenonetetracarboxylic dianhydride (BTDA) and, alternatively, isophthaloyldiphthalic anhydride (IDPA) into LaRC(TM)-IA polymer backbones. Exhibit higher glass-transition temperatures and retain greater fractions of lower-temperature shear moduli at higher temperatures. Copolyimides spun into fibers or used as adhesives, molding powders, or matrix resins in many applications, especially in fabrication of strong, lightweight structural components of aircraft.

  3. Evidence that the TM1-TM2 loop contributes to the rho1 GABA receptor pore.

    PubMed

    Filippova, Natalia; Wotring, Virginia E; Weiss, David S

    2004-05-14

    Considerable evidence indicates the second transmembrane domain (TM2) of the gamma-aminobutyric acid (GABA) receptor lines the integral ion pore. To further delineate the structures that constitute the ion pore and selectivity filter of the rho1 GABA receptor, we used the substituted cysteine accessibility method with charged reagents to identify anion- and cation-accessible surfaces. Twenty-one consecutive residues were mutated to cysteine, one at a time, in the presumed intracellular end of the first transmembrane domain (TM1; Ala(271)-Met(276)), the entire linker connecting TM1 to TM2 (Leu(277)-Arg(287)), and the presumed intracellular end of TM2 (Ala(288)-Ala(291)). Positively (MTSEA(+)) and negatively (pCMBS(-)) charged sulfhydryl reagents, as well as Cd(2+), were added extracellularly to test accessibility of the engineered cysteines. Four of the mutants, all at the intracellular end of TM2 (R287C, V289C, P290C, A291C), were accessible to positively charged reagents, whereas seven mutants (A271C, T272C, L277C, W279C, V280C, P290C, A291C) were functionally modified by negatively charged pCMBS(-). These seven modified residues were at the intracellular end of TM2, in the TM1-TM2 linker, and at the intracellular end of TM1. In nearly all cases (excluding P290C), the rate and the degree of modification were state-dependent, with greater accessibility in the presence of agonist. Select cysteine mutants were combined with a point mutation (A291E) that converted the pore from chloride- to non-selective. In this case, positively charged reagents could modify residues in the TM1-TM2 linker (Leu(277) and Val(280)), supporting the notion that the modifying reagents were reaching their target through the pore. Taken together, our results suggest that, up to its intracellular end, the TM2 domain is not charge selective. In addition, we propose that the TM1-TM2 linker and the intracellular end of TM1 are along the pathway of the permeating ion. These findings may lend new

  4. The tmRNA website: reductive evolution of tmRNA in plastids and other endosymbionts.

    PubMed

    Gueneau de Novoa, Pulcherie; Williams, Kelly P

    2004-01-01

    tmRNA combines tRNA- and mRNA-like properties and ameliorates problems arising from stalled ribosomes. Research on the mechanism, structure and biology of tmRNA is served by the tmRNA website (http://www.indiana.edu/~ tmrna), a collection of sequences, alignments, secondary structures and other information. Because many of these sequences are not in GenBank, a BLAST server has been added; another new feature is an abbreviated alignment for the tRNA-like domain only. Many tmRNA sequences from plastids have been added, five found in public sequence data and another 10 generated by direct sequencing; detection in early-branching members of the green plastid lineage brings coverage to all three primary plastid lineages. The new sequences include the shortest known tmRNA sequence. While bacterial tmRNAs usually have a lone pseudoknot upstream of the mRNA segment and a string of three or four pseudoknots downstream, plastid tmRNAs collectively show loss of pseudoknots at both postions. The pseudoknot-string region is also too short to contain the usual pseudoknot number in another new entry, the tmRNA sequence from a bacterial endosymbiont of insect cells, Tremblaya princeps. Pseudoknots may optimize tmRNA function in free-living bacteria, yet become dispensible when the endosymbiotic lifestyle relaxes selective pressure for fast growth.

  5. Synthesis and structure of nanocrystalline mixed Ce–Yb silicates

    SciTech Connect

    Małecka, Małgorzata A. Kępiński, Leszek

    2013-07-15

    Graphical abstract: - Highlights: • New method of synthesis of nanocrystalline mixed lanthanide silicates is proposed. • Formation of A-type (Ce{sub 1−y}Yb{sub y}){sub 2}Si{sub 2}O{sub 7} in well dispersed Ce{sub 1−x}Yb{sub x}O{sub 2−(x/2)}–SiO{sub 2} system. • Formation of Yb{sub y}Ce{sub 9.33−y}(SiO{sub 4}){sub 6}O{sub 2} in agglomerated Ce{sub 1−x}Yb{sub x}O{sub 2−(x/2)}–SiO{sub 2} system. - Abstract: This work presents results of studies on synthesis and structure of mixed, nanocrystalline Ce–Yb silicates. Using TEM, XRD and FTIR we showed that heat treatment of nanocrystalline Ce{sub 1−x}Yb{sub x}O{sub 2−(x/2)} (x = 0.3, 0.5) mixed oxide supported on amorphous silica in reducing atmosphere, results in formation of Ce–Yb mixed silicates. Dispersion of the oxide on the silica surface and thus a local lanthanide/Si atomic ratio determines the stoichiometry of the silicate. Oxide crystallites uniformly dispersed on the silica surface transformed into A-(Ce{sub 1−y}Yb{sub y}){sub 2}Si{sub 2}O{sub 7} disilicate, while the agglomerated nanoparticles converted into Yb{sub y}Ce{sub 9.33−y}(SiO{sub 4}){sub 6}O{sub 2} oxyapatite silicate as an intermediate phase.

  6. Optical properties of Yb ions in GaN epilayer

    NASA Astrophysics Data System (ADS)

    Jadwisienczak, W. M.; Lozykowski, H. J.

    2003-07-01

    In recent years, an important effort in semiconductor materials research has been devoted to III-nitrides semiconductors doped with rare earth ions due to the high potential of these materials in light-emitting device applications. Ytterbium (Yb 3+) is one of a few lanthanide ions which have not been investigated as an optically active center in these materials yet. In this paper we report the observation of luminescence from GaN films grown on sapphire (0 0 0 1) substrate by metal organic chemical vapor deposition and doped by implantation with Yb 3+ ions. The high resolution photo- and cathodoluminescence spectra of GaN:Yb 3+ were studied at different excitation conditions in temperatures ranging from 8 to 330 K and revealed weak thermal quenching. The luminescence emission lines are assigned to transitions between the spin-orbit levels 2F 5/2 → 2F 7/2 of Yb 3+ (4f 13). The analysis of the Yb luminescence spectra allowed us to suggest the energy level diagram of the crystal-field-split 4f 13 levels for the Yb ion center. The most probable lattice location of Yb in GaN is the substitutional Ga site. Furthermore, the luminescence kinetics of internal transitions of Yb 3+ incorporated in GaN was investigated by means of decay and time-resolved luminescence measurements. It was found that the ytterbium decay is non-exponential with dominant exponential term of ˜100 μs with little dependence on the ambient temperature. The results indicate that Yb-doped GaN epilayer may be suitable as a material for near infrared optoelectronic devices.

  7. New ternary phosphides and arsenides. Syntheses, crystal structures, physical properties of Eu{sub 2}ZnP{sub 2}, Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}

    SciTech Connect

    Wang, Jian; Xia, Sheng-Qing; Tao, Xu-Tang; Schäfer, Marion C.; Bobev, Svilen

    2013-09-15

    Three new europium pnictides Eu{sub 2}ZnP{sub 2}, Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3} have been synthesized and their structures were determined by single-crystal X-ray diffraction. Eu{sub 2}ZnP{sub 2} is isotypic with Yb{sub 2}CdSb{sub 2} (Cmc2{sub 1} (No. 36); cell parameters a=4.1777(7) Å, b=15.925(3) Å, c=7.3008(12) Å), while the latter two compounds crystallize with the Ba{sub 2}Cd{sub 2}Sb{sub 3} structure type (C2/m (No. 12); cell parameters a=15.653(5)/16.402(1) Å, b=4.127(1)/4.445(4) Å, c=11.552(4)/12.311(1) Å and β=126.647(4)/126.515(7)° for Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}, respectively). Magnetic susceptibility measurements in the interval 5–300 K confirm paramagnetic behavior and effective magnetic moments characteristic of Eu{sup 2+} ([Xe] 4f{sup 7}) ground states. Temperature-dependent electrical conductivity measurements also prove that Eu{sub 2}Cd{sub 2}As{sub 3} is a semiconducting compound with a narrow band gap of 0.059 eV below 100 K. According to TG/DSC analyses, Eu{sub 2}Cd{sub 2}As{sub 3} starts to decompose at about 950 K. - Graphical abstract: A polyhedral view of the crystal structure of new pnictides Eu{sub 2}T{sub 2}Pn{sub 3} (T=Zn or Cd; Pn=P or As). Display Omitted - Highlights: • Three new ternary pnictide Zintl compounds, Eu{sub 2}ZnP{sub 2}, Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}, have been synthesized and characterized. • The europium cations are divalent and ferromagnetically coupled in both Eu{sub 2}Zn{sub 2}P{sub 3} and Eu{sub 2}Cd{sub 2}As{sub 3}. • Eu{sub 2}Cd{sub 2}As{sub 3} has a very small band gap of 0.06 eV and starts to decompose over 950 K.

  8. Synthesis, crystal structure, and magnetism of A2Co12As7 (A=Ca, Y, Ce–Yb)

    SciTech Connect

    Tan, Xiaoyan; Ovidiu Garlea, V.; Chai, Ping; Geondzhian, Andrey Y.; Yaroslavtsev, Alexander A.; Xin, Yan; Menushenkov, Alexey P.; Chernikov, Roman V.; Shatruk, Michael

    2015-08-28

    In this study, ternary intermetallics, A2Co12As7 (A=Ca, Y, Ce–Yb), have been synthesized by annealing mixtures of elements in molten Bi at 1223 K. The materials obtained crystallize in the P63/m variant of the Zr2Fe12P7 structure type. The unit cell volume shows a monotonic decrease with the increasing atomic number of the rare-earth metal, with the exception of Ce-, Eu-, and Yb-containing compounds. An examination of these outliers with X-ray absorption near edge structures (XANES) spectroscopy revealed mixed valence of Ce, Eu, and Yb, with the average oxidation states of +3.20(1), +2.47(5), and +2.91(1), respectively, at room temperature. Magnetic behavior of A2Co12As7 is generally characterized by ferromagnetic ordering of Co 3d moments at 100–140 K, followed by low-temperature ordering of rare-earth 4f moments. The 3d-4f magnetic coupling changes from antiferromagnetic for A=Pr–Sm to ferromagnetic for A=Ce and Eu–Yb. Finally, polarized neutron scattering experiments were performed to support the postulated ferro- and ferrimagnetic ground states for Ce2Co12As7 and Nd2Co12As7, respectively.

  9. Er and Yb isotope fractionation in planetary materials

    NASA Astrophysics Data System (ADS)

    Albalat, Emmanuelle; Telouk, Philippe; Albarède, Francis

    2012-11-01

    Terrestrial planets are depleted in volatile elements relative to solar abundances. Little is known, however, about volatility at the high temperatures relevant to asteroidal collisions and to the giant lunar impact. Although refractory rare-earth elements have overall similar crystallochemical properties, some differ in their temperatures of condensation from the nebular gas. This is the case for Yb, which condenses at ˜1490K and in the vapor is mostly in elemental form. By contrast, Er, largely present as ErO, condenses at ˜1660K. We analyzed the Er and Yb isotopic compositions in 33 terrestrial basalts, garnets, different classes of chondrites and achondrites, and lunar samples by MC-ICP-MS. The range of mass-dependent isotope fractionation is larger for Yb (0.43‰ per amu) than Er (0.23‰) isotopes. For terrestrial rocks, a positive correlation between δYb and La/Yb suggests that the isotopic differences between Er and Yb can be accounted for by the presence of small fractions of Yb2+. Yb is isotopically heavy in kimberlite and light in garnets. Ytterbium behaves similarly to Fe, with Yb3+ being more incompatible than the much less abundant Yb2+. In addition, the coexistence of divalent and trivalent sites in the garnet structure and the preference of heavy isotopes for stable bonds makes Yb in garnet isotopically light. The deficit of heavy Yb isotopes in lunar basaltic samples relative to the Earth, chondrites, and eucrites provides new evidence that the Moon formed by the condensation of silicate vapor in the aftermath of the giant lunar impact. Separation of vapor from melt and of heavy from light isotopes is first expected during the adiabatic expansion of the initial vapor plume. Subsequently, friction between melt and gas tends to further enrich the Moon feeding zone in silicate vapor to compensate the inward migration of melt out of the pre-lunar disk. A major consequence of interpreting the present lunar data by vapor/melt segregation is that the

  10. Calorimetry Study of the Phase Diagrams of EuNi2Ge2 and Eu2Ni3Ge5 under Pressure

    NASA Astrophysics Data System (ADS)

    Esakki Muthu, Sankaran; Braithwaite, Daniel; Salce, Bernard; Nakamura, Ai; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2016-09-01

    We report here the phase diagrams of EuNi2Ge2 and Eu2Ni3Ge5 studied by ac calorimetry under pressure using a diamond anvil cell. We follow the antiferromagnetic transition for EuNi2Ge2 up to 1.5 GPa. The sudden disappearance of magnetic order at around 2 GPa is confirmed, consistent with the probable occurrence of a first-order valence transition near that pressure. The ac calorimetry results on Eu2Ni3Ge5 clearly show two antiferromagnetic transitions, and suggest that magnetic order persists up to higher pressure than previously expected. At high pressure, where heavy-fermion behavior has been reported, the Néel temperature is decreasing, and magnetic order is expected to disappear at an extrapolated pressure of 12-14 GPa. A semi quantitative analysis of the pressure dependence of the specific heat does not show any large changes, but is compatible with a moderate enhancement of γ. The phase diagrams of Yb and Ce heavy fermion systems are compared and discussed with our system.

  11. Laser tunability in Yb 3+:YCa 4O(BO 3) 3 {Yb:YCOB}

    NASA Astrophysics Data System (ADS)

    Shah, L.; Ye, Q.; Eichenholz, J. M.; Hammons, D. A.; Richardson, M.; Chai, B. H. T.; Peale, R. E.

    1999-08-01

    Tunable laser operation in Yb:YCOB from 1018 to 1087 nm pumped by 1.4 W from a Ti:Sapphire laser tuned to 900 nm is demonstrated. The combination of the ability to grow large crystals with high optical quality, broad infrared emission, diode pumpable absorption bands, and a significant non-linear coefficient makes this material very promising for use in tunable and ultrafast laser systems.

  12. EU pharmaceutical expenditure forecast

    PubMed Central

    Urbinati, Duccio; Rémuzat, Cécile; Kornfeld, Åsa; Vataire, Anne-Lise; Cetinsoy, Laurent; Aballéa, Samuel; Mzoughi, Olfa; Toumi, Mondher

    2014-01-01

    Background and Objectives With constant incentives for healthcare payers to contain their pharmaceutical budgets, forecasting has become critically important. Some countries have, for instance, developed pharmaceutical horizon scanning units. The objective of this project was to build a model to assess the net effect of the entrance of new patented medicinal products versus medicinal products going off-patent, with a defined forecast horizon, on selected European Union (EU) Member States’ pharmaceutical budgets. This model took into account population ageing, as well as current and future country-specific pricing, reimbursement, and market access policies (the project was performed for the European Commission; see http://ec.europa.eu/health/healthcare/key_documents/index_en.htm). Method In order to have a representative heterogeneity of EU Member States, the following countries were selected for the analysis: France, Germany, Greece, Hungary, Poland, Portugal, and the United Kingdom. A forecasting period of 5 years (2012–2016) was chosen to assess the net pharmaceutical budget impact. A model for generics and biosimilars was developed for each country. The model estimated a separate and combined effect of the direct and indirect impacts of the patent cliff. A second model, estimating the sales development and the risk of development failure, was developed for new drugs. New drugs were reviewed individually to assess their clinical potential and translate it into commercial potential. The forecast was carried out according to three perspectives (healthcare public payer, society, and manufacturer), and several types of distribution chains (retail, hospital, and combined retail and hospital). Probabilistic and deterministic sensitivity analyses were carried out. Results According to the model, all countries experienced drug budget reductions except Poland (+€41 million). Savings were expected to be the highest in the United Kingdom (−€9,367 million), France

  13. Eu doping and reduction into barium orthophosphates

    NASA Astrophysics Data System (ADS)

    Santos, Ricardo D. S.; dos S. Rezende, Marcos V.

    2016-08-01

    We investigated Eu3+ and Eu2+ ion incorporation and the reduction of Eu3+ ions in a LiBaPO4 lattice using atomistic simulations based on lattice energy minimization. We predicted the most probable sites occupied by Eu3+ and Eu2+ ions, and the related charge-compensation mechanisms involved in these substitutions to the most provable reduction agent for Eu reduction. It was found that Eu3+and Eu2+ ions are the most energetically favorable for incorporation at Ba site. In the case of the Eu3+ ion, charge compensation by the LiBa‧ antisite is the most provable. Eu3+ reduction involving a H2 reduction atmosphere is the most favorable. Our results reveal that Eu3+ and Eu2+ position plays an important role in the luminescence characteristic and in the persistent luminescence mechanisms related to LiBaPO4.

  14. Sympathetic cooling of 171 Yb+ qubit ions on a scalable ion trap chip using Yb isotopes

    NASA Astrophysics Data System (ADS)

    Kwon, Yeong-Dae; Ahn, Jun Sik; Hong, Seokjun; Lee, Minjae; Cheon, Hongjin; Cho, Dongil ``Dan''; Kim, Taehyun

    2016-05-01

    To achieve ion trap based large-scale quantum computing devices, motional states of qubit ions must be regulated against heating from ion transportation or noise on the chip surface while leaving internal states of the ions intact. Sympathetic cooling is a natural solution for this problem, but trapping two different species of ions generally requires two sets of optical devices including separate lasers for each ion type, increasing the complexity and the cost of the setup. We tested Doppler-cooled 174 Yb+ ions to sympathetically cool 171 Yb+ qubit ions. Since these two isotopes have energy levels close to each other, the optical setup can be vastly simplified. We also verified that the tail of non-ideally focused cooling beam and the scattered light from the surface create excited state population in the 171 Yb+ qubit ions, as expected. This leads to occasional spontaneous emission events, which currently limits the coherence time of our qubit to a few seconds. We will also discuss our plans for optimizing the experiment, which may increase the coherence time by one or two orders of magnitude. This work was partially supported by ICT R&D program of MSIP/IITP. [10043464, Development of quantum repeater technology for the application to communication systems].

  15. QCD For Intel(R) Xeon Phi(tm) and Xeon(tm) processors

    SciTech Connect

    Joo, Balint

    2014-09-11

    This library provides a library containing highly optimized Wilson-Dslash, Wilson Clover operator and Krylov subspace solvers for Lattice QCD simulations. The library is targeted at Intel(R) Xeon Phi(tm), and Intel(R) Xeon(tm) processors.

  16. Cage Structure Formation of Singly Doped Aluminum Cluster Cations Al n TM + ( TM = Ti, V, Cr)

    NASA Astrophysics Data System (ADS)

    Lang, Sandra M.; Claes, Pieterjan; Neukermans, Sven; Janssens, Ewald

    2011-09-01

    Structural information on free transition metal doped aluminum clusters, Al n TM + ( TM = Ti, V, Cr), was obtained by studying their ability for argon physisorption. Systematic size ( n = 5 - 35) and temperature ( T = 145 - 300 K) dependent investigations reveal that bare Al n + clusters are inert toward argon, while Al n TM + clusters attach one argon atom up to a critical cluster size. This size is interpreted as the geometrical transition from surface-located dopant atoms to endohedrally doped aluminum clusters with the transition metal atom residing in an aluminum cage. The critical size, n crit , is found to be surprisingly large, namely n crit = 16 and n crit = 19 - 21 for TM = V, Cr, and TM = Ti, respectively. Experimental cluster-argon bond dissociation energies have been derived as function of cluster size from equilibrium mass spectra and are in the 0.1-0.3 eV range.

  17. Modeling Cr-to-Tm and Cr-to-Tm-to-Ho energy transfer in YAG crystals

    NASA Technical Reports Server (NTRS)

    Swetits, John J.

    1991-01-01

    A systematic analysis of energy transfer processes in crystals of YAG doped with varying concentrations of Cr and Tm is described. Both spectral measurements and measurements of the temporal response to pulsed excitation are used to give independent determinations of the microscopic interaction parameter for Cr to Tm transfer. The different factors in influencing the temperature dependence of the Cr to Tm transfer are discussed. The dependence of the Tm cross-relaxation rate on Tm concentration is determined.

  18. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    DOE PAGES

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squaredmore » Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.« less

  19. Charge transfer processes and ultraviolet induced absorption in Yb:YAG single crystal laser materials

    NASA Astrophysics Data System (ADS)

    Rydberg, S.; Engholm, M.

    2013-06-01

    Charge transfer (CT) transitions and UV induced color centers in Yb:YAG single crystals have been investigated. A simultaneous pair formation of a stable Yb2+ ion and a hole related (O-) color center (hole polaron) are observed through a CT-process. Slightly different types of hole related color centers are formed in Yb:YAG crystals containing small levels of iron impurities. Furthermore, excitation spectroscopy on the UV irradiated Yb:YAG samples could confirm an energy transfer process between Yb3+ and Yb2+ ions. The findings are important for an increased knowledge of the physical loss mechanisms observed in Yb-doped laser materials, such as the nonlinear decay process in Yb:YAG crystals as well as the photodarkening phenomenon in Yb-doped fiber lasers.

  20. Level densities and gamma-ray strength functions in 170,171,172-Yb

    SciTech Connect

    Agvaanluvsan, U; Schiller, A; Becker, J; Bernstein, L; Garrett, P; Guttormsen, M; Mitchell, G; Rekstad, J; Siem, S; Voinov, A; Younes, W

    2004-07-28

    Level densities and radiative strength functions in {sup 171}Yb and {sup 170}Yb nuclei have been measured using the {sup 171}Yb({sup 3}He{sup 3}He{gamma}){sup 171}Yb and {sup 171}Yb({sup 3}He,{alpha}{gamma}){sup 170}Yb reactions. New data on {sup 171}Yb are compared to a previous measurement for {sup 171}Yb from the {sup 172}Yb({sup 3}He,{alpha}{gamma}){sup 171}Yb reaction. Systematics of level densities and radiative strength functions in {sup 170,171,172}Yb are established. The entropy excess in {sup 171}Yb relative to the even-even nuclei {sup 170,172}Yb due to the unpaired neutron quasiparticle is found to be approximately 2k{sub B}. Results for the radiative strength function from the two reactions lead to consistent parameters characterizing the ''pygmy'' resonances. Pygmy resonances in the {sup 170,172}Yb populated by the ({sup 3}He,{alpha}) reaction appear to be split into two components for both of which a complete set of resonance parameters are obtained.

  1. Application of Yb:YAG short pulse laser system

    DOEpatents

    Erbert, Gaylen V.; Biswal, Subrat; Bartolick, Joseph M.; Stuart, Brent C.; Crane, John K.; Telford, Steve; Perry, Michael D.

    2004-07-06

    A diode pumped, high power (at least 20W), short pulse (up to 2 ps), chirped pulse amplified laser using Yb:YAG as the gain material is employed for material processing. Yb:YAG is used as the gain medium for both a regenerative amplifier and a high power 4-pass amplifier. A single common reflective grating optical device is used to both stretch pulses for amplification purposes and to recompress amplified pulses before being directed to a workpiece.

  2. Materials Data on EuTmCuS3 (SG:63) by Materials Project

    SciTech Connect

    Kristin Persson

    2014-11-02

    Computed materials data using density functional theory calculations. These calculations determine the electronic structure of bulk materials by solving approximations to the Schrodinger equation. For more information, see https://materialsproject.org/docs/calculations

  3. Lifetimes of high-spin states in {sup 162}Yb

    SciTech Connect

    Carpenter, M.P.; Janssens, R.V.F.; Henry, R.G.

    1995-08-01

    A measurement on lifetimes of high-spin states in the yrast and near-yrast rotational bands in {sup 162}Yb was carried out at ATLAS in order to determine the evolution of collectivity as a function of angular momentum using the {sup 126}Te({sup 40}Ar,4n){sup 162}Yb reaction at 170 MeV. Previous lifetime measurements in the {sup 164,166,168}Yb isotopes showed a dramatic decrease in the transition quadrupole moment Q{sub t} with increasing spin. It was suggested that this decrease in Q{sub t} is brought about by the rotationally-induced deoccupation of high-j configurations, mainly i{sub 13/2} neutrons. If this interpretation is correct, the heavier isotopes should have a larger decrease in Q{sub t} than the lighter mass nuclides due to the position of the Fermi surface in the i{sub 13/2} subshell. Indeed, {sup 160}Yb does not show a clear decrease in Q{sub t} at high spin. No high spin lifetime information exists for {sup 162}Yb, thus this experiment fills the gap of measured Q{sub t}`s in the light Yb series. The data is currently being analyzed.

  4. Nanoscale Conducting and Insulating Domains on YbB6

    NASA Astrophysics Data System (ADS)

    Hoffman, Jennifer; Zhu, Zhihuai; He, Yang; Kim, Dae-Jeong; Fisk, Zachary

    Recent photoemission studies on YbB6 reported a metallic surface but without f-states pinned at the Fermi level, in contradiction to the theoretical prediction of YbB6 as a topological Kondo insulator. Thus the topological nature of YbB6 remains unclear and requires a study that can distinguish trivial surface structure and non-trivial topological effects derived from the bulk. We use scanning tunneling microscopy and spectroscopy (STM/STS) to provide a real-space microscopic picture of the surface electronic structure in YbB6. We observe coexisting nanoscale metallic and insulating surface terminations. The surface conductivity of each termination reflects the degree of downward or upward band bending that is determined by the surface polarity. In addition to demonstrating that surface metallically in YbB6 stems from band bending at the polar surface, our study suggests the utility of YbB6 for creating spin-polarized p-n junctions at the atomic scale. We acknowledge funding from the National Science Foundation, DMR-1410480.

  5. Linearly polarized single TM mode terahertz waveguide.

    PubMed

    Li, Haisu; Ren, Guobin; Atakaramians, Shaghik; Kuhlmey, Boris T; Jian, Shuisheng

    2016-09-01

    We design a hollow-core terahertz (THz) waveguide guiding a single linearly polarized mode. This is achieved using a hybrid cladding, where we introduce a ring of subwavelength structures, including metal wires and air-holes. The wire-based cladding is extremely anisotropic, reflecting only transverse magnetic (TM) modes. The polarization of TM modes is further manipulated by replacing some wires with air-holes. Numerical simulations confirm the guidance of only an x-polarized TM2 mode over 0.36-0.46 THz in a wavelength-scale core (diameter of 1 mm). The propagation losses are of the order 0.25  dB/cm, with low bend losses <0.3  dB/cm at 0.4 THz for a bend radius of 5 cm. PMID:27607958

  6. Multimodal bioimaging using rare earth doped Gd2O2S: Yb/Er phosphor with upconversion luminescence and magnetic resonance properties.

    PubMed

    Ajithkumar, G; Yoo, Benjamin; Goral, Dara E; Hornsby, Peter J; Lin, Ai-Ling; Ladiwala, Uma; Dravid, Vinayak P; Sardar, Dhiraj K

    2013-03-21

    While infrared upconversion imaging using halide nanoparticles are so common the search for a very efficient halide free upconverting phosphors is still lacking. In this article we report Gd2O2S:Yb/Er,YbHo,YbTm systems as a very efficient alternative phosphors that show upconversion efficiency comparable or even higher than existing halide phosphors. While the majority of rare earth dopants provide the necessary features for optical imaging, the paramagnetic Gd ion also contributes to the magnetic imaging,thereby resulting in a system with bimodal imaging features. Results from imaging of the nanoparticles together with aggregates of cultured cells have suggested that imaging of the particles in living animals may be possible. In vitro tests revealed no signficant toxicity because no cell death was observed when the nanoparticles were in the presence of growing cells in culture. Measurement of the magnetization of the phosphor shows that the particles are strongly magnetic, thus making them suitable as an MRI agent.

  7. Spectroscopic properties and laser performances of Yb:YCOB and potential of the Yb:LaCOB material

    NASA Astrophysics Data System (ADS)

    Aron, A.; Aka, G.; Viana, B.; Kahn-Harari, A.; Vivien, D.; Druon, F.; Balembois, F.; Georges, P.; Brun, A.; Lenain, N.; Jacquet, M.

    2001-02-01

    In order to increase the compacity of the Yb-doped lasers, YCOB (Ca 4Y(BO 3) 3) materials with high ytterbium concentration have been characterized. Large 15 at.% and 35 at.% ytterbium-doped single crystals were grown by the Czochralski pulling method. Spectroscopic and laser properties have been investigated and laser tests performed under titanium sapphire and diode pumping at 976 nm. Low thresholds under Ti:Sa pumping (50 mW) and high slope efficiency under diode pumping (66%) have been obtained. The optical quality and the distribution of Yb 3+ dopant through the highly doped crystals is discussed. First results on the Yb:LaCOB crystals grown by the Czochralski process, containing 46Yb 3+ at.%, are also presented.

  8. 10 W single-mode Er/Yb co-doped all-fiber amplifier with suppressed Yb-ASE

    NASA Astrophysics Data System (ADS)

    Sobon, G.; Sliwinska, D.; Abramski, K. M.; Kaczmarek, P.

    2014-02-01

    In this work we demonstrate a single-frequency, single-mode all-fiber master oscillator power amplifier (MOPA) source, based on erbium-ytterbium co-doped double-clad fiber emitting 10 W of continuous wave power at 1565 nm. In the power amplifier stage, the amplified spontaneous emission from Yb3+ ions (Yb-ASE) is forced to recirculate in a loop resonator in order to provide stable lasing at 1060 nm. The generated signal acts as an additional pump source for the amplifier and is reabsorbed by the Yb3+ ions in the active fiber, allowing an increase in the efficiency and boosting the output power. The feedback loop also protects the amplifier from parasitic lasing or self-pulsing at a wavelength of 1 μm. This allows one to significantly scale the output power in comparison to a conventional setup without any Yb-ASE control.

  9. Landsat TM and ETM+ Thermal Band Calibration

    NASA Technical Reports Server (NTRS)

    Barsi, Julia A.; Hook, Simon J.; Palluconi, Frank D.; Schott, John R.; Raqueno, Nina G.

    2006-01-01

    Landsat-5 Thematic Mapper (TM) has been imaging the Earth since March 1984 and Landsat-7 Enhanced Thematic Mapper Plus (ETM+) was added to the series of Landsat instruments in April 1999. The stability and calibration of the ETM+ has been monitored extensively since launch. Though not monitored for many years, TM now has a similar system in place to monitor stability and calibration. University teams have been evaluating the on-board calibration of the instruments through ground-based measurements since 1999. This paper considers the calibration efforts for the thermal band, Band 6, of both the Landsat-5 and Landsat-7 instruments.

  10. Beta-Decay Study of ^{150}Er, ^{152}Yb, and ^{156}Yb: Candidates for a Monoenergetic Neutrino Beam Facility

    SciTech Connect

    Estevez Aguado, M. E.; Algora, A.; Rubio, B.; Bernabeu, J.; Nacher, E.; Tain, J. L.; Gadea, A.; Agramunt, J.; Burkard, K.; Hueller, W.; Doring, J.; Kirchner, R.; Mukha, I.; Plettner, C.; Roeckl, E.; Grawe, H.; Collatz, R.; Hellstrom, M.; Cano-Ott, D.; Karny, M.; Janas, Z.; Gierlik, M.; Plochocki, A.; Rykaczewski, Krzysztof Piotr; Batist, L.; Moroz, F.; Wittman, V.; Blazhev, A.; Valiente, J. J.; Espinoza, C.

    2011-01-01

    The beta decays of ^{150}Er, ^{152}Yb, and ^{156}Yb nuclei are investigated using the total absorption spectroscopy technique. These nuclei can be considered possible candidates for forming the beam of a monoenergetic neutrino beam facility based on the electron capture (EC) decay of radioactive nuclei. Our measurements confirm that for the cases studied, the EC decay proceeds mainly to a single state in the daughter nucleus.

  11. Physical properties of superbulky lanthanide metallocenes: synthesis and extraordinary luminescence of [Eu(II)(Cp(BIG))2] (Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl).

    PubMed

    Harder, Sjoerd; Naglav, Dominik; Ruspic, Christian; Wickleder, Claudia; Adlung, Matthias; Hermes, Wilfried; Eul, Matthias; Pöttgen, Rainer; Rego, Daniel B; Poineau, Frederic; Czerwinski, Kenneth R; Herber, Rolfe H; Nowik, Israel

    2013-09-01

    The superbulky deca-aryleuropocene [Eu(Cp(BIG))2], Cp(BIG) = (4-nBu-C6H4)5-cyclopentadienyl, was prepared by reaction of [Eu(dmat)2(thf)2], DMAT = 2-Me2N-α-Me3Si-benzyl, with two equivalents of Cp(BIG)H. Recrystallizyation from cold hexane gave the product with a surprisingly bright and efficient orange emission (45% quantum yield). The crystal structure is isomorphic to those of [M(Cp(BIG))2] (M = Sm, Yb, Ca, Ba) and shows the typical distortions that arise from Cp(BIG)⋅⋅⋅Cp(BIG) attraction as well as excessively large displacement parameter for the heavy Eu atom (U(eq) = 0.075). In order to gain information on the true oxidation state of the central metal in superbulky metallocenes [M(Cp(BIG))2] (M = Sm, Eu, Yb), several physical analyses have been applied. Temperature-dependent magnetic susceptibility data of [Yb(Cp(BIG))2] show diamagnetism, indicating stable divalent ytterbium. Temperature-dependent (151)Eu Mössbauer effect spectroscopic examination of [Eu(Cp(BIG))2] was examined over the temperature range 93-215 K and the hyperfine and dynamical properties of the Eu(II) species are discussed in detail. The mean square amplitude of vibration of the Eu atom as a function of temperature was determined and compared to the value extracted from the single-crystal X-ray data at 203 K. The large difference in these two values was ascribed to the presence of static disorder and/or the presence of low-frequency torsional and librational modes in [Eu(Cp(BIG))2]. X-ray absorbance near edge spectroscopy (XANES) showed that all three [Ln(Cp(BIG))2] (Ln = Sm, Eu, Yb) compounds are divalent. The XANES white-line spectra are at 8.3, 7.3, and 7.8 eV, for Sm, Eu, and Yb, respectively, lower than the Ln2O3 standards. No XANES temperature dependence was found from room temperature to 100 K. XANES also showed that the [Ln(Cp(BIG))2] complexes had less trivalent impurity than a [EuI2(thf)x] standard. The complex [Eu(Cp(BIG))2] shows already at room temperature

  12. Biosimilar regulation in the EU.

    PubMed

    Kurki, Pekka; Ekman, Niklas

    2015-01-01

    In the EU, the EMA has been working with biosimilars since 1998. This experience is crystallized in the extensive set of guidelines, which range from basic principles to details of clinical trials. While the guidance may appear complicated, it has enabled the development of biosimilars, of which 21 have managed to get marketing authorization. Currently marketed biosimilars in the EU have a good track record in safety and traceability. No biosimilars have been withdrawn from the market because of safety concerns. The most controversial issues with biosimilars are immunogenicity and extrapolation of therapeutic indications. The available data for these topics do not raise concerns among EU regulators. Interchangeability and substitution are regulated by individual EU member states. PMID:26294076

  13. HSP60 interacts with YB-1 and affects its polysome association and subcellular localization

    SciTech Connect

    Ohashi, Sachiyo; Atsumi, Megumi; Kobayashi, Shunsuke

    2009-08-07

    YB-1 is a DNA/RNA-binding protein which, in the cytoplasm, associates with polysomes and regulates translation. However, YB-1 has a novel nuclear localization signal, and its nuclear accumulation is correlated with cancer induction. Here we designated the amino-acid sequence as YB-NLS and demonstrated that YB-NLS is necessary for the nuclear translocation of overexpressed YB-1 in NG108-15 cells. In addition, we found that a heat shock protein, HSP60, binds to YB-NLS in the cytoplasm. Interestingly, when HSP60 expression was repressed, an increase of polysome-associated YB-1 was observed in heavy-sedimenting fractions on a sucrose gradient. Overexpression of HSP60 resulted in a decrease of YB-1 in the heavy-sedimenting fractions and suppression of YB-NLS activity. Furthermore, the NLS-deleted YB-1 was apparently associated with the heavy-sedimenting polysomes. These results suggest that HSP60 interacts with YB-1 at the YB-NLS region and acts as a regulator of polysome association and the subcellular distribution of YB-1.

  14. Associations with Minspeak[TM] Icons

    ERIC Educational Resources Information Center

    van der Merwe, Elmarie; Alant, Erna

    2004-01-01

    Although the Minspeak[TM] approach is used on communication devices worldwide, little research has been conducted on its applicability within specific cultural contexts. The impact that users' familiarity of symbols and associations can have on learnability necessitates more systematic research. This study was an investigation into the…

  15. TE and TM pass integrated optic polarizers

    NASA Astrophysics Data System (ADS)

    Madaan, Divya; Kaur, Davinder; Sharma, V. K.; Kapoor, A.

    2016-05-01

    A four layer integrated optical waveguide is studied, in which a high index buffer is used along with the metal cladding. The structure can act both as TE and TM pass polarizer. We have designed it for λ=1.55 µm which corresponds to telecommunication wavelength. TiO2 is used as a buffer layer with Au as metal cladding. When metal clad optical waveguides with a high index buffer layer are used there is periodic coupling between lossless modes of waveguide and the lossy modes supported by high index buffer layer with metal clad. We present theoretical results of the effect of buffer thickness on the mode index and the losses. The TM Pass polarizer with TE and TM losses, 1029.19dB/cm and 59.67dB/cm respectively are obtained. Also, TE Pass polarizer with TM and TE losses 1444.74dB/cm and 238.51dB/cm respectively are obtained.

  16. Defying Gravity Using Jenga[TM] Blocks

    ERIC Educational Resources Information Center

    Tan, Yin-Soo; Yap, Kueh-Chin

    2007-01-01

    This paper describes how Jenga[TM] blocks can be used to demonstrate the physics of an overhanging tower that appears to defy gravity. We also propose ideas for how this demonstration can be adapted for the A-level physics curriculum. (Contains 8 figures and 1 table.)

  17. The Neuroscience of PowerPoint[TM

    ERIC Educational Resources Information Center

    Horvath, Jared Cooney

    2014-01-01

    Many concepts have been published relevant to improving the design of PowerPoint[TM] (PP) presentations for didactic purposes, including the redundancy, modality, and signaling principles of multimedia learning. In this article, we review the recent neuroimaging findings that have emerged elucidating the neural structures involved in many of these…

  18. 75 FR 78236 - Lock+TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-15

    ... would be sold to a local utility. Applicant Contact: Mr. Mark R. Stover, Hydro Green Energy LLC, 5090... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Lock+\\TM\\ Hydro Friends Fund XLVII, FFP Missouri 16, LLC, et al.; Notice...

  19. 75 FR 78233 - Lock+TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-15

    ... sold to a local utility. Applicant Contact: Mr. Mark R. Stover, Hydro Green Energy LLC, 5090 Richmond... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Lock+\\TM\\ Hydro Friends Fund XXXVII; FFP Missouri 6, LLC; Solia...

  20. 75 FR 78234 - Lock+TM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-12-15

    ... Contact: Mr. Mark R. Stover, Hydro Green Energy LLC, 5090 Richmond Avenue 390, Houston, TX 77056; phone... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF ENERGY Federal Energy Regulatory Commission Lock+ TM Hydro Friends Fund XXXVIII, FFP Missouri 12, LLC, et al.; Notice...

  1. Crystal field excitations of YbMn2Si2

    NASA Astrophysics Data System (ADS)

    Mole, R. A.; Hofmann, M.; Adroja, D. T.; Moze, O.; Campbell, S. J.

    2013-12-01

    The crystal field excitations of the rare earth intermetallic compound YbMn2Si2 have been measured by inelastic neutron scattering over the temperature range 2.5-50 K. The YbMn2Si2 spectra exhibit three low energy excitations (~3-7 meV) in the antiferromagnetic AFil region above the magnetic phase transition at TN2 = 30(5) K. The crystal field parameters have been determined for YbMn2Si2 in the antiferromagnetic AFil region. A further two inelastic excitations (~9 meV, 17 meV) are observed below TN2=30(5) K, the temperature at which the high temperature antiferromagnetic structure is reported to exhibit doubling of the magnetic cell. Energy level diagrams have been determined for Yb3+ ions in the different sites above (single site) and below the magnetic transition temperature (two sites). The excitation energies for both sites are shown to be temperature independent with the temperature dependences of the transition intensities for the two sites described well by a simple Boltzmann model. The spectra below TN2 cannot be described fully in terms of molecular field models based on either a single Yb3+ site or two Yb3+ sites. This indicates that the magnetic behaviour of YbMn2Si2 is more complicated than previously considered. The inability to account fully for excitations below the magnetic phase transition may be due to an, as yet, unresolved structural transition associated with the magnetic transition.

  2. CCRS proposal for evaluating LANDSAT-4 MSS and TM data

    NASA Technical Reports Server (NTRS)

    Strome, W. M.; Cihlar, J.; Goodenough, D. G.; Guertin, F. E. (Principal Investigator); Guindon, B.; Murphy, J.; Butlin, J. M.; Duff, P.; Fitzgerald, A.; Grieve, G.

    1984-01-01

    The measurement of registration errors in LANDSAT MSS data is discussed as well as the development of a revised algorithm for the radiometric calibration of TM data and the production of a geocoded TM image.

  3. Interactions of CT DNA with hexagonal NaYF4 co-doped with Yb3+/Tm3+ upconversion particles

    NASA Astrophysics Data System (ADS)

    Yuan, Xiuxue; Gu, Wenchao; Xiao, Mengsi; Xie, Wenli; Wei, Shaohua; Zhou, Lin; Zhou, Jiahong; Shen, Jian

    2015-02-01

    The interaction of UCPs with CT DNA are studied in detail by zeta potential, Energy dispersive spectrometer (EDS) spectroscopy, Thermogravimetric (TGA) analysis, DNA melting determination and various spectroscopic techniques including Ultraviolet-Visible (UV-Vis) absorption, fluorescence, circular dichroism (CD), Fourier transform infrared (FTIR) and Raman spectroscopy. The results indicate that CT DNA can assemble on the surface of UCPs mainly by relative stronger hydrophobic force and electrostatic binding, and the predominant interaction site is the deoxyribosyl phosphate backbone of CT DNA. Moreover, after interacting with UCPs, the double helix structure of DNA is undamaged.

  4. Near-IR photoactivation using mesoporous silica-coated NaYF4:Yb,Er/Tm upconversion nanoparticles.

    PubMed

    Gnanasammandhan, Muthu Kumara; Idris, Niagara Muhammad; Bansal, Akshaya; Huang, Kai; Zhang, Yong

    2016-04-01

    Photoactivation is a process in which light is used to 'activate' photolabile therapeutics. As a therapeutic strategy, its advantages are that it is noninvasive and that a high degree of spatial and temporal control is possible. However, conventional photoactivation techniques are hampered by the limited penetration depth of the UV and visible lights to which the photosensitive compounds are responsive. Here we describe a protocol for the use of upconversion nanoparticles (UCNs) as light transducers to convert deeply penetrating near-infrared (NIR) light to UV-visible wavelengths matching that of the absorption spectrum of photosensitive therapeutics. This allows the use of deep-penetrating and biologically friendly NIR light instead of low-penetrating and/or toxic visible or UV lights for photoactivation. In this protocol, we focus on two photoactivation applications: photodynamic therapy (PDT) and photoactivated control of gene expression. We describe how to prepare and characterize the UCNs, as well as how to check their function in biochemical assays and in cells. For both applications, the UCNs are coated with mesoporous silica for easy loading of the therapeutics. For PDT, the UCNs are coated with polyethylene glycol (PEG) for stabilization and folic acid for tumor targeting and then loaded with photosensitizers that would be expected to kill cells by singlet oxygen production; the nanoparticles are injected intravenously. For photoactivated control of gene expression, knockdown of essential tumor genes is achieved using UCNs loaded with caged nucleic acids, which are injected intratumorally. The whole process from nanoparticle synthesis to animal studies takes ∼36 d. PMID:26963631

  5. Relative radiometric calibration of LANDSAT TM reflective bands

    NASA Technical Reports Server (NTRS)

    Barker, J. L.

    1984-01-01

    Raw thematic mapper (TM) calibration data from pre-launch tests and in-orbit acquisitions from LANDSAT 4 and 5 satellites are analyzed to assess the radiometric characteristics of the TM sensor. A software program called TM radiometric and algorithmic performance program (TRAPP) was used for the majority of analyses. Radiometric uncertainty in the final TM image originates from: (1) scene variability (solar irradiance and atmospheric scattering); (2) optical and electrical variability of the sensor; and (3) variability introduced during image processing.

  6. Investigation of loss processes of Tm and Tm,Ho in YAG

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Bair, C. H.; Inge, A. T.; Hess, R. V.

    1991-01-01

    The loss of excitation from various manifolds of Tm and Tm,Ho in YAG as a function of temperature and concentration is studied. Two probable loss mechanisms - a Tm up-conversion and a Ho up-conversion - are identified. A 785-nm CW diode laser with 400-nW peak power was focused to a small spot on the sample. The emission from the sample observed at 90 deg was monitored through a monochromator with slits open to 3 mm. Intensity of emission was measured by varying the power of the excitation source using a set of neutral density filters. Power is reported as the percentage of the peak power, and the intensity curves were normalized below 20 percent of transmission. The fact that there is emission above the pump energy indicates an up-conversion from excited manifolds. Nonlinear changes in the intensity of the emission from the Tm 3F4 manifold with the pump power reveals a loss of excitation from this manifold. The linear dependence of the 5I7 manifold emission with pump power at low Tm and high Ho concentrations and the gain of energy in the 5I6 manifold of Ho indicate that the 5I7 manifold loss is due to the coupling of Tm and Ho ions.

  7. High-pressure synthesis, crystal structure, and structural relationship of the first ytterbium fluoride borate Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9}

    SciTech Connect

    Haberer, Almut; Huppertz, Hubert

    2009-04-15

    Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} was synthesized under high-pressure/high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 deg. C, representing the first known ytterbium fluoride borate. The compound exhibits isolated BO{sub 3}-groups next to ytterbium cations and fluoride anions, showing a structure closely related to the other known rare-earth fluoride borates RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}. Monoclinic Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} crystallizes in space group C2/c with the lattice parameters a=2028.2(4) pm, b=602.5(2) pm, c=820.4(2) pm, and beta=100.63(3){sup o} (Z=4). Three different ytterbium cations can be identified in the crystal structure, each coordinated by nine fluoride and oxygen anions. None of the five crystallographically independent fluoride ions is coordinated by boron atoms, solely by trigonally-planar arranged ytterbium cations. In close proximity to the above mentioned compounds RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}, Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9} can be described via alternating layers with the formal compositions 'YbBO{sub 3}' and 'YbF{sub 3}' in the bc-plane. - Graphical abstract: High-pressure/high-temperature synthesis (multianvil technique) led to the first ytterbium fluoride borate Yb{sub 5}(BO{sub 3}){sub 2}F{sub 9}, built up from isolated BO{sub 3}-groups. The compound shows structural relations to the known rare-earth fluoride borates RE{sub 3}(BO{sub 3}){sub 2}F{sub 3} (RE=Sm, Eu, Gd) and Gd{sub 2}(BO{sub 3})F{sub 3}.

  8. Design of highly doped Yb3+ fiber ring laser

    NASA Astrophysics Data System (ADS)

    Huang, Xiu-jiang; Liu, Yong-zhi; Sui, Zhan; Li, Ming-zhong; Lin, Hong-huan; Wang, Jian-jun; Zhao, De-shuang; Wang, Feng-rui; Chen, Ji-xin

    2005-01-01

    Ytterbium-doped silica fibers exhibit very broad absorption and emission bands, from 800nm to 1064nm for absorption and 970nm to 1200nm for emission. Therefore wide band lasers can be obtained using a wide variety of pump lasers. In this paper, the characteristics of high-doped Yb3+ fiber are analyzed and verified by experiment and a highly-doped Yb3+ fiber ring laser with short cavity has been presented. Comparing with normal Yb3+doped fiber, the relationship between the important characteristics of the Yb3+doped fiber laser such as threshold power, output power and laser parameters such as pump power, fiber length, output couple ratio is analyzed. Numerical results are coincident with the experiment phenomenon very well. A 1053 nm pulse has been achieved in our fiber laser. The output power is 6mW as pump power is 110mW and the slope efficiency is 17%. The Yb3+ fiber laser we produced can be used as a stable source in obtaining ultrafast pulse, fiber sense and optical communications.

  9. Yb3+/Ho3+-codoped antimony-silicate optical fiber

    NASA Astrophysics Data System (ADS)

    Żmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

    The emission properties of Yb3+/Ho3+-codoped antimony-silicate optical fiber has been investigated. Luminescence at 2.1 μm corresponding to 5I7--> 5I8 transition in holmium was obtained by energy transfer between Yb3+ and Ho3+ ions. According to the Dexter-Miyakawa model, the parameters of energy migration CDD of the 2F5/2 (Yb3+) <--> 2F5/2 (Yb3+) transition and direct energy transfer CDA of the 2F5/2 (Yb3+) --> 5I6 (Ho3+) transition was calculated. The optimization of the activator content and the concentration ratio were conducted with the purpose of maximizing the efficiency of energy transfer. It made possible to select best-suited glass which was used to manufacture double-clad optical fiber. Strong and narrow bands of spontaneous emission which formed as a result of energy transfer between ytterbium and holmium ions were observed in the fiber under exciting with radiation at 978 nm wavelength.

  10. Yb3+/Ho3+-codoped antimony-silicate optical fiber

    NASA Astrophysics Data System (ADS)

    Żmojda, Jacek; Dorosz, Dominik; Kochanowicz, Marcin; Miluski, Piotr; Dorosz, Jan

    2012-05-01

    The emission properties of Yb3+/Ho3+-codoped antimony-silicate optical fiber has been investigated. Luminescence at 2.1 μm corresponding to 5I7--> 5I8 transition in holmium was obtained by energy transfer between Yb3+ and Ho3+ ions. According to the Dexter-Miyakawa model, the parameters of energy migration CDD of the 2F5/2 (Yb3+) <--> 2F5/2 (Yb3+) transition and direct energy transfer CDA of the 2F5/2 (Yb3+) --> 5I6 (Ho3+) transition was calculated. The optimization of the activator content and the concentration ratio were conducted with the purpose of maximizing the efficiency of energy transfer. It made possible to select best-suited glass which was used to manufacture double-clad optical fiber. Strong and narrow bands of spontaneous emission which formed as a result of energy transfer between ytterbium and holmium ions were observed in the fiber under exciting with radiation at 978 nm wavelength.

  11. Pioneers--The "Engineering byDesign[TM]" Network

    ERIC Educational Resources Information Center

    Burke, Barry N.

    2006-01-01

    This article discusses the standards-based instruction model, Engineering byDesign[TM] (EbD), and a network of teachers called the Engineering byDesign[TM] Network. Engineering byDesign[TM] is the only standards-based national model for Grades K-12 that delivers technological literacy which was developed by the International Technology Education…

  12. Radiative lifetime measurements of some Tm I and Tm II levels by time-resolved laser spectroscopy

    NASA Astrophysics Data System (ADS)

    Tian, Yanshan; Wang, Xinghao; Yu, Qi; Li, Yongfan; Gao, Yang; Dai, Zhenwen

    2016-04-01

    Radiative lifetimes of 88 levels of Tm I in the energy range 22 791.176-48 547.98 cm-1 and 29 levels of Tm II in the range 27 294.79-65 612.85 cm-1 were measured by time-resolved laser-induced fluorescence spectroscopy in laser-ablation plasma. The lifetime values obtained are in the range from 15.4 to 7900 ns for Tm I and from 36.5 to 1000 ns for Tm II. To the best of our knowledge, 77 lifetimes of Tm I and 22 lifetimes of Tm II are reported for the first time. Good agreements between the present results and the previous experimental values were achieved for both Tm I and Tm II.

  13. Use of Yb(III) Centered Near Infra-Red (NIR) Luminescence to Determine the Hydration State of a 3,2-HOPO based MRI-Contrast Agent

    SciTech Connect

    Moore, Evan G.; Seitz, Michael; Raymond, Kenneth N.

    2008-06-09

    It has been more than a decade since the first reports of [Gd(Tren-Me-3,2-HOPO)(H{sub 2}O){sub 2}] as a potential new class of magnetic resonance imaging contrast agent (MRI-CA). The defining feature of these 1-methyl-3-hydroxypyridin-2-one (Me-3,2-HOPO) based compounds has been the use of a hexadentate ligand design, and hence an increase in the number of metal bound water molecules, without sacrificing complex stability compared to the typically octadentate contrast agents used commercially. Since that time, significant advances in the properties of these chelates have been steadily reported, including improvements in relaxivity, incorporation into macromolecular architectures and, recently, the first direct verification of solution structure using the discovery of Eu(III) centered luminescence with the isomeric 1-hydroxypyridin-2-one (1,2-HOPO) chelate as a sensitizing chromophore. Nonetheless, it has remained frustrating that direct measurements of the inner sphere hydration state, q, using luminescence techniques with the parent Me-3,2-HOPO compounds have remained elusive, even when direct laser excitation of weakly absorbing f-f transitions were employed (eg. for Eu(III) complexes). This failing can likely be traced to the presence of a low lying LMCT state which efficiently quenches metal based emission. Instead, estimates of the q and hence solution structure have relied on the fitting of relaxivity data to the Solomon-Bloembergen-Morgan equations or, where sufficiently soluble in aqueous solution, studies on the temperature dependence of the paramagnetic contribution to the water {sup 17}O NMR transverse relaxation rate. Recently, Beeby et al reported on a qualitative equation to determine inner sphere hydration based on the change in lifetimes for Yb(III) in going from H{sub 2}O to D{sub 2}O solution, and we reasoned that the lower energy accepting state of Yb(III) may lie below the LMCT state which quenches Eu(III) emission, and hence may facilitate

  14. Reliability and Validity of the Zephyr[TM] BioHarness[TM] to Measure Respiratory Responses to Exercise

    ERIC Educational Resources Information Center

    Hailstone, Jono; Kilding, Andrew E.

    2011-01-01

    The Zephyr[TM] BioHarness[TM] (Zephyr Technology, Auckland, New Zealand) is a wireless physiological monitoring system that has the ability to measure respiratory rate unobtrusively. However, the ability of the BioHarness[TM] to accurately and reproducibly determine respiratory rate across a range of intensities is currently unknown. The aim of…

  15. High-spin states in Yb156 and structure evolutions at large angular momenta in even-A Yb isotopes

    NASA Astrophysics Data System (ADS)

    Li, Z. Y.; Hua, H.; Wang, S. Y.; Meng, J.; Li, Z. H.; Li, X. Q.; Xu, F. R.; Liu, H. L.; Zhang, S. Q.; Ye, Y. L.; Jiang, D. X.; Zheng, T.; Ma, L. Y.; Lu, F.; Fan, F. Y.; Han, L. Y.; Wang, H.; Xiao, J.; Chen, D.; Fang, X.; Lou, J. L.; Zhou, S. G.; Zhu, L. H.; Wu, X. G.; Li, G. S.; He, C. Y.; Liu, Y.; Li, X. Q.; Hao, X.; Pan, B.; Li, L. H.

    2008-06-01

    High-spin states of Yb156 have been studied via the Sm144(O16,4n)Yb156 fusion-evaporation reaction at beam energy 102 MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. In the present work, the negative-parity sequence above the 25- state was found to be irregular and fragment into many parallel branches. This pattern may related to the excitation from the nucleon in the Z=64,N=82 core. The characteristics of alignment plot and E-GOS curve for the positive-parity yrast sequence in Yb156 indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. Based on a systematic summary of the available experimental alignments for the even-A Yb156,158,160,162,164 isotopes, the structural evolutions induced by the increase in angular momentum, as well as by the change in neutron numbers, in these even-A Yb isotopes have been discussed in comparison with the cranked Woods-Saxon-Strutinsky calculations by means of total-Routhian-surface (TRS) methods.

  16. Point-contact spectroscopy of YbBe13

    NASA Astrophysics Data System (ADS)

    Nowack, A.; Wasser, S.; Schlabitz, W.; Kvitnitskaya, O. E.; Fisk, Z.

    1997-12-01

    Among rare-earth and actinide Be13 intermetallic compounds, YbBe13 is anomalous, with evidence for mixed-valence and heavy-fermion behavior. The resistivity is comparatively low and the resulting large mean free path enables point-contact spectroscopy in the ballistic regime. In the d2V/dI2 characteristics of point contacts between YbBe13 and normal metals, measured at temperatures between 0.2 and 40 K, we find structures due to crystal-field and Kondo scattering. The characteristics show a pronounced asymmetry, which we explain by the enhanced effective electronic mass in YbBe13 and by a shift of the chemical potential in the contact region due to the nonthermal occupation of excited crystal-field levels.

  17. Unique magnetic structure of YbCo2Si2

    NASA Astrophysics Data System (ADS)

    Mufti, N.; Kaneko, K.; Hoser, A.; Gutmann, M.; Geibel, C.; Krellner, C.; Stockert, O.

    2016-07-01

    We report on the results of powder and single-crystal neutron diffraction to investigate the magnetic order in YbCo2Si2 below the Néel temperature TN=1.7 K in detail. Two different magnetically ordered phases can clearly be distinguished. At lowest temperatures a commensurate magnetic structure with a propagation vector k1=(0.25 0.25 1 ) is found, while the intermediate phase (T >0.9 K) is characterized by an incommensurate magnetic structure with k2=(0.25 0.086 1 ) . The magnetic structure in YbCo2Si2 is in marked contrast to all other known R Co2Si2 compounds (R = rare earth element) likely due to some itineracy of the Yb 4 f states being responsible for the magnetism.

  18. 980 nm narrow linewidth Yb-doped phosphate fiber laser

    NASA Astrophysics Data System (ADS)

    Li, Pingxue; Yao, Yifei; Hu, Haowei; Chi, Junjie; Yang, Chun; Zhao, Ziqiang; Zhang, Guangju

    2014-12-01

    A narrow-linewidth ytterbium (Yb)-doped phosphate fiber laser based on fiber Bragg grating (FBG) operating around 980 nm is reported. Two different kinds of cavity are applied to obtain the 980 nm narrow-linewidth output. One kind of the cavity consists of a 0.35 nm broadband lindwidth high-reflection FBG and the Yb-doped phosphate fiber end with 0° angle, which generates a maximum output power of 25 mW. The other kind of resonator is composed of a single mode Yb-doped phosphate fiber and a pair of FBGs. Over 10.7 mW stable continuous wave are obtained with two longitudinal modes at 980 nm. We have given a detailed analysis and discussion for the results.

  19. Yb:YAG Lasers for Space Based Remote Sensing

    NASA Technical Reports Server (NTRS)

    Ewing, J.J.; Fan, T. Y.

    1998-01-01

    Diode pumped solid state lasers will play a prominent role in future remote sensing missions because of their intrinsic high efficiency and low mass. Applications including altimetry, cloud and aerosol measurement, wind velocity measurement by both coherent and incoherent methods, and species measurements, with appropriate frequency converters, all will benefit from a diode pumped primary laser. To date the "gold standard" diode pumped Nd laser has been the laser of choice for most of these concepts. This paper discusses an alternate 1 micron laser, the YB:YAG laser, and its potential relevance for lidar applications. Conceptual design analysis and, to the extent possible at the time of the conference, preliminary experimental data on the performance of a bread board YB:YAG oscillator will be presented. The paper centers on application of YB:YAG for altimetry, but extension to other applications will be discussed.

  20. Sequential growth of sandwiched NaYF4:Yb/Er@NaYF4:Yb@NaNdF4:Yb core-shell-shell nanoparticles for photodynamic therapy

    NASA Astrophysics Data System (ADS)

    Peng, Huang-Yong; Ding, Bin-Bin; Ma, Yin-Chu; Sun, Shi-Qi; Tao, Wei; Guo, Yan-Chuan; Guo, Hui-Chen; Yang, Xian-Zhu; Qian, Hai-Sheng

    2015-12-01

    Upconversion (UC) nanostructures have attracted much interest for their extensive biological applications. In this work, we describe a sequential synthetic route to prepare sandwiched NaYF4:Yb/Er@NaYF4:Yb@NaNdF4:Yb core-shell upconversion nanoparticles. The as-prepared products were investigated by X-ray diffraction (XRD) and transmission electron microscopy (TEM, JEM 2100F), respectively. The as-prepared core-shell nanoparticles of NaYF4:Yb/Er@NaYF4:Yb@NaNdF4:Yb are composed of elliptical nanoparticles with a length of 80 nm and width of 42 nm, which show efficient upconversion fluorescence excited at 808 nm indicating the formation of core-shell-shell sandwiched nanostructures. In addition, the as-prepared sandwiched NaYF4:Yb/Er@NaYF4:Yb@NaNdF4:Yb core-shell upconversion nanoparticles also show strong upconversion fluorescence excited at 980 nm. Amphiphilic mPEG2k-b-PEBEP6K copolymers (denoted as PPE) were chosen to transfer these hydrophobic UCNPs into the aqueous phase for biological application. In vitro photodynamic therapy of cancer cells show that the viability of cells incubated with the nanoparticles loaded with MC 540 was significantly lower as compared to the nanoparticles without photosensitizers exposed to NIR laser.

  1. Determination of the 151Eu(n,γ)152Eu and 153Eu(n,γ)154Eu Reaction Cross Sections at Thermal Neutron Energy

    NASA Astrophysics Data System (ADS)

    Basunia, M. S.; Firestone, R. B.; Révay, Zs.; Choi, H. D.; Belgya, T.; Escher, J. E.; Hurst, A. M.; Krtička, M.; Szentmiklósi, L.; Sleaford, B.; Summers, N. C.

    2014-05-01

    We have measured partial γ-ray cross sections following neutron capture in enriched 151Eu and 153Eu targets at the cold-neutron-beam facility of the Budapest Research Reactor. The cross sections were standardized using a stoichiometric natEuCl3 target with the well-known 1951-keV γ-ray cross section from the 35Cl(n,γ)36Cl reaction at the cold-neutron-beam facility of the Garching Research Reactor. The γ-ray cross sections were corrected for effective g-factors. These data were combined with the structural information of 152Eu and 154Eu given in the Evaluated Nuclear Structure Data File to produce capture γ-ray level schemes. The total radiative capture cross sections of the 151Eu(n,γ)152Eu and 153Eu(n,γ)154Eu reactions were determined by summing the experimental transition intensities from known levels with simulated intensities of transitions from higher excitations to the ground- or metastable-state. The individual 151Eu(n,γ)152Eu and 151Eu(n,γ)152gEu reaction cross sections disagree with values in the literature. However, the total cross section of the 151Eu(n,γ)152Eu reaction does agree with those values. Also, our deduced cross section for the 153Eu(n,γ)154Eu reaction closely follows the data in the literature. These results are supported by an earlier standardization experiment done at the Budapest Research Reactor using a target of Eu2O3 solution in H2SO4.

  2. Evaluating LANDSAT-4 MSS and TM data

    NASA Technical Reports Server (NTRS)

    Strome, W. M.; Cihlar, J.; Goodenough, D. G.; Guertin, F. E. (Principal Investigator); Murphy, J. M.; Grieve, G.; Simard, R.; Horler, D.; Ahern, F. J.

    1984-01-01

    Interband line pixel misregistrations were determined for the four MSS bands of the Mistassini, Ontario scene and multitemporal registration of LANDSAT-4 products were tested for two different geocoded scenes. Line and pixel misregistrations are tabulated as determined by the manual ground control points and the digital band to band correlation techniques. A method was developed for determining the spectral information content of TM images for forestry applications.

  3. Preliminary Evaluation of TM for Soils Information

    NASA Technical Reports Server (NTRS)

    Thompson, D. R.; Henderson, K. E.; Houston, A. G.; Pitts, D. E.

    1984-01-01

    Thematic mapper data acquired over Mississippi County, Arkansas, were examined for utility in separating soil associations within generally level alluvium deposited by the Mississippi River. The 0.76 to 0.90 micron (Band 4) and the 1.55 to 1.75 micron (Band 5) were found to separate the different soil associations fairly well when compared to the USDA-SCS general soil map. The thermal channel also appeared to provide information at this level. A detailed soil survey was available at the field level along with ground observations of crop type, plant height, percent cover and growth stage. Soils within the fields ranged from uniform to soils that occur as patches of sand that stand out strongly against the intermingled areas of dark soil. Examination of the digital values of individual TM bands at the field level indicates that the influence of the soil is greater in TM than it was in MSS bands. The TM appears to provide greater detail of within field variability caused by soils than MSS and thus should provide improved information relating to crop and soil properties. However, this soil influence may cause crop identification classification procedures to have to account for the soil in their algorithms.

  4. Cryogenic Tm:YAP microchip laser

    NASA Astrophysics Data System (ADS)

    Hubka, Zbyněk.; Å ulc, Jan; Jelínková, Helena; Nejezchleb, Karel; Å koda, Václav

    2016-04-01

    The spectral characteristics of laser active media, and thus those of the laser output, are temperature dependent. Specifically, in almost every crystal host, cooling to low temperatures leads to better heat removal, a higher efficiency and output power, and a reduced lasing threshold. Tm-ion doped lasers have an emission wavelength around 2 μm and are important in medicine for soft tissue cutting and hemostasis, as well as in LIDAR or atmosphere sensing technology. This paper presents the performance-temperature dependency of a 4 at. % doped Tm:YAP microchip. During the experiment the Tm:YAP crystal was placed inside an evacuated liquid nitrogen cryostat on a cooling finger. As its temperature was varied from 80 K to 340 K, changes were observed in the absorption spectrum, ranging from 750 nm to 2000 nm and in the fluorescence spectrum from 1600 nm to 2050 nm. Fluorescence lifetime was seen to rise and fall with decreasing temperature. The laser was pumped by a 792 nm laser diode and at 80 K the maximum output peak power of the laser was 4.6 W with 23 % slope efficiency and 0.6 W threshold, compared to 2.4 W output peak power, 13 % slope efficiency and 3.3 W threshold when at 340 K. The laser emission wavelength changed from 1883 nm to 1993 nm for 80 K and 300 K, respectively.

  5. Synchrotron Radiation Diffraction Study of YbInCu4

    NASA Astrophysics Data System (ADS)

    Utsumi, Yuki; Sato, Hitoshi; Moriyoshi, Chikako; Kuroiwa, Yoshihiro; Namatame, Hirofumi; Taniguchi, Masaki; Hiraoka, Koichi; Kojima, Kenichi; Sugimoto, Kunihisa

    2011-05-01

    The structural change of an YbInCu4 single crystal has been investigated associated with the first-order valence-transition at TV = 42 K using synchrotron radiation diffraction. The Yb-Cu and In-Cu interatomic distances abruptly increase below TV, following the lattice expansion with no change in the C15b-type crystal structure. We find that the distance between Cu ions forming the Cu4 cluster in the crystal is almost unchanged across the valence transition. No abrupt change in the thermal rotational motion of the Cu4 cluster is observed at TV.

  6. Investigation of lasing characteristics of domestic Yb : YAG laser ceramics

    NASA Astrophysics Data System (ADS)

    Snetkov, I. L.; Palashov, O. V.; Osipov, V. V.; Mukhin, I. B.; Maksimov, R. N.; Shitov, V. A.; Luk'yashin, K. E.

    2016-07-01

    We report on the synthesis and laser characteristics of Yb3+-doped yttrium aluminium garnet (Y3Al5O12) optical ceramics. The ceramics was produced by solid-phase reactive sintering of a mixture of Yb (5 at %) : Y2O3 and Al2O3 nanopowders synthesised by laser ablation, using additional calcination of the mixture before compaction. In a thin disk geometry, multiwatt laser oscillation was obtained at a wavelength of 1030 nm with a power of 5.2 W and a slope efficiency of 37.0% at a pump pulse period-toduration ratio of 5.72.

  7. Measurements of optical Feshbach resonances of 174Yb atoms

    NASA Astrophysics Data System (ADS)

    Kim, Min-Seok; Lee, Jeongwon; Lee, Jae Hoon; Shin, Y.; Mun, Jongchul

    2016-10-01

    We present measurements of the optical Feshbach resonances (OFRs) of 174Yb atoms for the intercombination transition. We measure the photoassociation (PA) spectra of a pure 174Yb Bose-Einstein condensate (BEC) and determine the dependence of OFRs on PA laser intensities and frequencies for four least-bound vibrational levels near the intercombination transition. We confirm that our measurements are consistent with the temporal decay of a BEC subjected to a PA beam in the vicinity of the fourth vibrational level from the dissociation limit.

  8. EU Space Awareness: Initial implemenation

    NASA Astrophysics Data System (ADS)

    Russo, Pedro

    2015-08-01

    EU Space Awareness uses the excitement of space to attract young people into science and technology and stimulate European and global citizenship. The project will show children and teenagers the opportunities offered by space science and engineering and inspire primary-school children when their curiosity is high and their value systems are being formed. EU Space Awareness, a 3-year project, has started in March 2015 with 10 partner organisations and 15 network nodes in 17 European countries and the IAU Office of Astronomy for Development. During this talk we will give a update about the intial implementation of the project and its relevant for astronomy for development.

  9. Tuning Upconversion Emission of β-NaGdF4:Yb+/Ho3+ Nanorods Through Yb3+.

    PubMed

    Gao, Fangqi; Gao, Wei; Wang, Ruibo; Yan, Longxiang; Li, Jinping; Zheng, Hairong

    2016-04-01

    Yb3+/Ho3+ doped hexagonal NaGdF4 nanocrystals are synthesized through solvothermal method, for which pure hexagonal phased nanorods are presented. The concentration influence of Yb3+ ions on the sample morphology and fluorescence emission of Ho3+ is investigated. It is found that the sample size is changed from 25 nm to 125 nm and the upconversion emission is tuned from green to yellow when the concentration of Yb3+ ions is increased from 5.0 mol% to 50.0 mol%. The possible upconversion mechanism and the improvement of crystallinity are carefully investigated. It is suggested that the cross-relaxation process between Ho3+ ions promotes the red emission and quenches the green emission. PMID:27451703

  10. High pressure synthesis of a new phase of YbAg2: Structure, valence of Yb and properties

    DOE PAGES

    Tsvyashchenko, A. V.; Menushenkov, A. P.; Sidorov, V. A.; Petrova, A. E.; Fomicheva, L. N.; Chernysheva, O. V.; Lebed, Yu. B.; Axenov, S. N.; Bud’ko, S. L.; Sun, Liling; et al

    2015-08-05

    The new phase of YbAg2 was obtained using high-pressure and high-temperature reaction. YbAg2 crystallizes in the MgZn2 structure (the space group P63/mmc space group, No 194) with a = 5.68153(3) Å and c = 9.31995(7) Å and the unit cell volume V = 260.54(3) Å3. The XANES analysis showed that the valence state of Yb is +2.8. The low-temperature dependences of the electrical resistivity and magnetic susceptibility can be adequately described by a T2 term that supports the Fermi-liquid picture. Furthermore, the Kadowaki–Woods relation gives a low value of the degeneracy (N = 2).

  11. High pressure synthesis of a new phase of YbAg2: Structure, valence of Yb and properties

    SciTech Connect

    Tsvyashchenko, A. V.; Menushenkov, A. P.; Sidorov, V. A.; Petrova, A. E.; Fomicheva, L. N.; Chernysheva, O. V.; Lebed, Yu. B.; Axenov, S. N.; Bud’ko, S. L.; Sun, Liling; Zhao, Zhongxian

    2015-08-05

    The new phase of YbAg2 was obtained using high-pressure and high-temperature reaction. YbAg2 crystallizes in the MgZn2 structure (the space group P63/mmc space group, No 194) with a = 5.68153(3) Å and c = 9.31995(7) Å and the unit cell volume V = 260.54(3) Å3. The XANES analysis showed that the valence state of Yb is +2.8. The low-temperature dependences of the electrical resistivity and magnetic susceptibility can be adequately described by a T2 term that supports the Fermi-liquid picture. Furthermore, the Kadowaki–Woods relation gives a low value of the degeneracy (N = 2).

  12. Absolute calibration accuracy of L4 TM and L5 TM sensor image pairs

    USGS Publications Warehouse

    Chander, G.; Micijevic, E.

    2006-01-01

    The Landsat suite of satellites has collected the longest continuous archive of multispectral data of any land-observing space program. From the Landsat program's inception in 1972 to the present, the Earth science user community has benefited from a historical record of remotely sensed data. However, little attention has been paid to ensuring that the data are calibrated and comparable from mission to mission, Launched in 1982 and 1984 respectively, the Landsat 4 (L4) and Landsat 5 (L5) Thematic Mappers (TM) are the backbone of an extensive archive of moderate resolution Earth imagery. To evaluate the "current" absolute accuracy of these two sensors, image pairs from the L5 TM and L4 TM sensors were compared. The approach involves comparing image statistics derived from large common areas observed eight days apart by the two sensors. The average percent differences in reflectance estimates obtained from the L4 TM agree with those from the L5 TM to within 15 percent. Additional work to characterize the absolute differences between the two sensors over the entire mission is in progress.

  13. Magnetization and transport properties of single crystalline RPd2P2 (R=Y, La–Nd, Sm–Ho, Yb)

    DOE PAGES

    Drachuck, Gil; Böhmer, Anna E.; Bud'ko, Sergey L.; Canfield, Paul C.

    2016-05-27

    Single crystals of RPd2P2 (R=Y, La–Nd, Sm–Ho, Yb) were grown out of a high temperature solution rich in Pd and P and characterized by room-temperature powder X-ray diffraction, anisotropic temperature- and field-dependent magnetization and temperature-dependent in-plane resistivity measurements. In this series, YPd2P2 and LaPd2P2 YbPd2P2 (with Yb2+) are non-local-moment bearing. Furthermore, YPd2P2 and LaPd2P2 are found to be superconducting with Tc≃0.75 and 0.96 K respectively. CePd2P2 and PrPd2P2 magnetically order at low temperature with a ferromagnetic component along the crystallographic c-axis. The rest of the series manifest low temperature antiferromagnetic ordering. EuPd2P2 has Eu2+ ions and both EuPd2P2 and GdPd2P2 have isotropic paramagnetic susceptibilities consistent with L =0 and J=S=more » $$\\frac{7}{2}$$ and exhibit multiple magnetic transitions. For R=Eu–Dy, there are multiple, T>1.8 K transitions in zero applied magnetic field and for R=Nd, Eu, Gd, Tb, and Dy there are clear metamagnetic transitions at T=2.0 K for H< 55 kOe. Strong anisotropies arising mostly from crystal electric field (CEF) effects were observed for most magnetic rare earths with L≠0. The experimentally estimated CEF parameters B$_2^0$ were calculated from the anisotropic paramagnetic θab and θc values and compared to theoretical trends across the rare earth series. Lastly, the ordering temperatures as well as the polycrystalline averaged paramagnetic Curie–Weiss temperature, θave, were extracted from magnetization and resistivity measurements, and compared to the de-Gennes factor.« less

  14. Optical properties of Yb-doped Y 2SiO 5 thin films

    NASA Astrophysics Data System (ADS)

    Denoyer, A.; Jandl, S.; Viana, B.; Guillot-Noël, O.; Goldner, P.; Pelenc, D.; Thibault, F.

    2007-11-01

    Yb-doped Y2SiO5 thin films Raman active phonons and crystal-field (CF) excitations have been studied by Raman spectroscopy and infrared transmission, and compared to the single crystals results. The thin films, grown on Y2SiO5 undoped substrate, have been co-doped with Ge, Gd or La in order to adjust the lattice mismatch. Raman active phonon bandwidths indicate that thin films present less strains and defects than single crystals. Interesting thin films properties, such as Yb3+ site occupancies and Yb3+-Yb3+ pair interaction types, may be adjusted by the co-dopants. Infrared absorption shows notably that La3+ is a good co-doping ion to enhance selectively one of the two Yb sites and pair satellite contributions. Ge and Gd co-dopants may also be used to form independently Yb3+-Yb3+ ion pairs with either ferromagnetic or antiferromagnetic dominant interactions.

  15. Fabrication and XAFS analysis of Yb3+ doped yttrium lanthanum oxide transparent ceramics

    NASA Astrophysics Data System (ADS)

    Jiang, Cen; Yang, Qiuhong; Lu, Qing; Zhang, Haojia

    2013-12-01

    (YbxY0.90-xLa0.10)2O3 (x = 0.01-0.10) transparent ceramics were fabricated and their structural properties were investigated. The XRD showed our samples exhibited single cubic Y2O3 phase. The lattice parameters were refined with the Rietveld method. The compact structure and an average grain size of 40-50 μm were revealed by the microstructure. The local fine structure around Yb ions was investigated by using the XAFS (X-ray absorption fine structure) technique. The results showed that: the local structure around Yb ions in the samples with different concentration of Yb ions was basically similar, and Yb ions replaced Y position to form the solid solution. The Yb ions were trivalent. With the concentration of Yb2O3 increased, the coordination number (N) and first shell Yb-O bond length (R) decreased, and the degree of disorder (σ) increased.

  16. Optical waveguide formed in Yb:GdCOB and Yb:YCOB crystals by 3.0MeV O+ implantation

    NASA Astrophysics Data System (ADS)

    Jiao, Yang

    2013-07-01

    Planar optical waveguides were formed in Yb:GdCOB and Yb:YCOB crystals by 3.0 MeV O+ ion implantation at fluence of 2 × 1015 ions/cm2 at room temperature, respectively. The prism coupling method was performed to characterize the dark-mode property of the waveguides. The refractive index profiles in the waveguides were reconstructed by reflectivity calculation method (RCM). The results show that after the implantation, a 1.5 μm-wide region with enhanced refractive-index was formed beneath the sample surfaces to act as waveguide structures for both Yb:GdCOB and Yb:YCOB.

  17. Laser brackets debonding: Tm:YAP and ClarityTM SL self-ligating appliance system

    NASA Astrophysics Data System (ADS)

    Dostálová, Tatjana; Jelínková, Helena; Šulc, Jan; Koranda, Petr; Němec, Michal; Jelínek, Michal; Fibrich, Martin; Michalik, Pavel; Miyagi, Mitsunobu

    2010-02-01

    The study demonstrates the possibility of using Tm:YAP laser radiation for the removing ceramic brackets. The amount of enamel loss and residual resin on teeth has been evaluated. A diode-pumped Tm:YAP microchip laser generating at wavelength 1.9 μm was used for the debonding process. The transmission and absorption measurement of the basic elements - bracket, adhesive resin, and enamel was analyzed to explain the source of the heat and bracket debonding. Quantitative measurements are made for visualizing enamel surface before and after a self-ligating bonding technique. Temperature rise observation during the debonding procedure - from 0.5 to 2 W power - has improved the accuracy of assessment. The results were evaluated by CCD camera and scanning electron microscope. From the measurements it is possible to conclude that continuously running small diode pumped Tm:YAP microchip laser having output power 1W can remove the ceramic bracket without enamel iatrogenic damage.

  18. Genome-wide analysis of the human Alu Yb-lineage

    PubMed Central

    2004-01-01

    The Alu Yb-lineage is a 'young' primarily human-specific group of short interspersed element (SINE) subfamilies that have integrated throughout the human genome. In this study, we have computationally screened the draft sequence of the human genome for Alu Yb-lineage subfamily members present on autosomal chromosomes. A total of 1,733 Yb Alu subfamily members have integrated into human autosomes. The average ages of Yb-lineage subfamilies, Yb7, Yb8 and Yb9, are estimated as 4.81, 2.39 and 2.32 million years, respectively. In order to determine the contribution of the Alu Yb-lineage to human genomic diversity, 1,202 loci were analysed using polymerase chain reaction (PCR)-based assays, which amplify the genomic regions containing individual Yb-lineage subfamily members. Approximately 20 per cent of the Yb-lineage Alu elements are polymorphic for insertion presence/absence in the human genome. Fewer than 0.5 per cent of the Yb loci also demonstrate insertions at orthologous positions in non-human primate genomes. Genomic sequencing of these unusual loci demonstrates that each of the orthologous loci from non-human primate genomes contains older Y, Sg and Sx Alu family members that have been altered, through various mechanisms, into Yb8 sequences. These data suggest that Alu Yb-lineage subfamily members are largely restricted to the human genome. The high copy number, level of insertion polymorphism and estimated age indicate that members of the Alu Yb elements will be useful in a wide range of genetic analyses. PMID:15588477

  19. TE/TM Simulations of Interferometric Measurements

    NASA Technical Reports Server (NTRS)

    Houshmand, Bijan

    2000-01-01

    Interferometric synthetic aperture radar (IFSAR) measurements at X-, C-, L-, and P-band are used to derive ground topography at meter level resolution. Interpretation of the derived topography requires attention due to the complex interaction of the radar signal with ground cover. The presence of penetrable surfaces such as vegetation, and tree canopies poses a challenge since the depth of penetration depends on a number of parameters such as the operating radar frequency, polarization, incident angle, as well as terrain structure. The dependence of the reconstructed topography on polarization may lead to the characterization of the ground cover. Simulation of interferometric measurements is useful for interpretation of the derived topography (B. Houshmand, Proceedings of URSI, 314, 1997). In this talk , time domain simulations for interferometric measurement for TE- and TM- polarization are presented. Time domain simulation includes the effects of the surface material property as well geometry comparable the radar signal wavelength (B. Houshmand, Proceedings of the URSI, 25, 1998). The IFSAR simulation is carried out in two steps. First, the forward scattering data is generated based on full wave analysis. Next, the electromagnetic information is inverted to generate surface topography. This inversion is based on the well known IFSAR processing technique which is composed of signal compression, and formation of an interferogram. The full wave forward scattering data is generated by the scattered-field formulation of the FDTD algorithm. The simulation is carried out by exciting the computational domain by a radar signal. The scattered field is then computed and translated to the receiving interferometric antennas using the time-domain Huygen's principle. The inversion process starts by compressing the time-domain data. The range compressed data from both receivers are then coregistered to form an interferogram. The resulting interferogram is then related to the

  20. Post-adsorption process of Yb phosphate nano-particle formation by Saccharomyces cerevisiae

    NASA Astrophysics Data System (ADS)

    Jiang, MingYu; Ohnuki, Toshihiko; Tanaka, Kazuya; Kozai, Naofumi; Kamiishi, Eigo; Utsunomiya, Satoshi

    2012-09-01

    In this study, we have investigated the post-adsorption process of ytterbium (Yb) phosphate nano-particle formation by Saccharomyces cerevisiae (yeast). The yeast grown in P-rich medium were exposed to 1.44 × 10-4 mol/L Yb(III) solution for 2-120 h, and 2 months at 25 ± 1 °C at an initial pH of 3, 4, or 5, respectively. Ytterbium concentrations in solutions decreased as a function of exposure time. Field-emission scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy (FESEM), transmission electron microscopy (TEM), and synchrotron-based extended X-ray absorption fine structure (EXAFS) analyses revealed that nano-sized blocky Yb phosphate with an amorphous phase formed on the yeast cells surfaces in the solutions with Yb. These nano-sized precipitates that formed on the cell surfaces remained stable even after 2 months of exposure at 25 ± 1 °C around neutral pHs. The EXAFS data revealed that the chemical state of the accumulated Yb on the cell surfaces changed from the adsorption on both phosphate and carboxyl sites at 30 min to Yb phosphate precipitates at 5 days, indicating the Yb-phosphate precipitation as a major post-adsorption process. In addition, the precipitation of Yb phosphate occurred on cell surfaces during 7 days of exposure in Yb-free solution after 2 h of exposure (short-term Yb adsorption) in Yb solution. These results suggest that the released P from the inside of yeast cells reacted with adsorbed Yb on cell surfaces, resulting in the formation of Yb precipitates, even though no P was added to the exposure solution. In an abiotic system, the EXAFS data showed that the speciation of sorbed Yb on the reference materials, carboxymethyl cellulose and Ln resin, did not change even when the Yb was exposed to P solution, without forming Yb phosphate precipitates. This result strongly suggests that the cell surface of the yeast plays an important role in the Yb-phosphate precipitation process, not only as a carrier of the

  1. Graphing Calculators, the CBL2[TM] and TI-Interactive[TM] in High School Science.

    ERIC Educational Resources Information Center

    Molnar, Bill

    This collection of activities is designed to show how TI-Interactive[TM] and Calculator-based Laboratories (CBL) can be used to explore topics in high school science. The activities address such topics as specific heat, Boyle's Law, Newton's Law of Cooling, and Antarctic Ozone Levels. Teaching notes and calculator instructions are included as are…

  2. Optical Properties of Tm(3+) Ions in Alkali Germanate Glass

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.; Barnes, Norman P.; Reichle, Donald J.; Jiang, Shibin

    2006-01-01

    Tm-doped alkali germanate glass is investigated for use as a laser material. Spectroscopic investigations of bulk Tm-doped germanate glass are reported for the absorption, emission and luminescence decay. Tm:germanate shows promise as a fiber laser when pumped with 0.792 m diodes because of low phonon energies. Spectroscopic analysis indicates low nonradiative quenching and pulsed laser performance studies confirm this prediction by showing a quantum efficiency of 1.69.

  3. High-efficiency wavelength and polarization selective grating-waveguide structures for Yb:YAG thin-disk lasers

    NASA Astrophysics Data System (ADS)

    Rumpel, Martin; Abdou Ahmed, Marwan; Voss, Andreas; Graf, Thomas

    2012-06-01

    We report on Grating Waveguide Structures (GWS) with a high diffraction efficiency used in Littrow configuration to select (and tune) the wavelength of an Yb:YAG thin-disk laser. The structures are composed of a multilayer HR coating, on which an additional low index layer (SiO2) and high index layer (Ta2O5) was deposited. A binary grating with a period of 580 nm is etched on top of the structure with a groove depth of 87 nm for GWS 1 and 72 nm for GWS 2. The simulation results show that the diffraction efficiency in the -1st order can reach a value of 99.99% for TE polarization, whereas it is only about 20% for TM polarization at 1030 nm. The grating was fabricated by standard interference lithography followed by a dry etching process to the desired groove depth. The spectroscopic measurement exhibited a diffraction efficiency of 99.6% for GWS 1 at 1030 nm and 99.7% for GWS 2 at 1048 nm. The devices were placed as end-mirror into the resonator of a Yb:YAG thin-disk laser. An output power of up to 110 W could be obtained from the laser in fundamental-mode operation (M2 ~ 1.2) with GWS 1, corresponding to an optical efficiency of ηoo = 36.2%. In multi-mode operation (M2 ~ 6) a power of 325 W with ηoo = 53.2% could be extracted. The spectral bandwidth of the emitted beam was measured using an Optical Spectrum Analyzer (OSA) to be less than 20 pm in fundamental-mode. We also showed a continuous wavelength tuning range of 46 nm for GWS 1 and of 38 nm for GWS 2. With a commercially available Stokes polarimeter the degree of linear polarization (DOLP) was measured to be higher than 98.6% over the whole power and wavelength tuning range.

  4. Mechanism of tantalum adhesion on SiLK{sup TM}

    SciTech Connect

    Hu Yue; Yang Shuowang; Chen Xiantong; Lu Dong; Feng Yuanping; Wu Ping

    2005-09-19

    Tantalum adhesion on SiLK{sup TM} was investigated using first-principles method based on density functional theory. Phenylene groups were found to play a major role and the adjacent semi-benzene rings also contribute significantly to Ta adhesion on SiLK{sup TM}. In addition, the degradation effects of H{sub 2}/He reactive plasma clean on Ta adhesion on SiLK{sup TM} was investigated. Based on our findings, argon plasma treatment was suggested and implemented after reactive plasma cleaning process, which resulted in integration of SiLK{sup TM} with Cu up to seven metal layers.

  5. Radiometric comparison of the Landsat-5 TM and MSS sensors

    NASA Astrophysics Data System (ADS)

    Royer, Alain; Charbonneau, Lise; Brochu, Richard; Murphy, Jennifer M.; Teillet, Philippe M.

    1987-04-01

    The radiometric accuracy of Landsat-5 TM data and MSS data is evaluated. The TM and MSS images employed in the study were recorded simultaneously over Montreal on August 4, 1984. The radiometric and geometric correction procedures of the Canada Center for Remote Sensing are described. TM and MSS normalized and corrected apparent reflectances computed for 11 different cover types (four water areas, three urban areas having different densities, and four vegetative surfaces) are compared. It is observed that the normalized and corrected apparent reflectances from TM and MSS correlate well; and the usefulness of the processing procedure is validated.

  6. Different Scanning Instruments Comparison: MOMS And TM

    NASA Astrophysics Data System (ADS)

    Fusco, L.; Hsu, A.

    1986-11-01

    The Modular Optoelectronic Multispectral Scanner (MOMS), a CCD type sensor, was flown on two Shuttle missions, STS-7 and STS-11, for experimental purpose. Two MOMS scenes from STS-11 mission were given to the Earthnet Programme Office, European Space Agency for image quality analysis. However, the Thematic Mapper (TM) data from Landsat 5 which represent the state-of-the-art of current remote sensing technology are the only available auxiliary data. Based on some primitive analyses using the TM data as reference, we can conclude as follows: 1) The registration accuracy between the two MOMS spectral bands is good. However, the algorithm for the radiometric calibration of MOMS detectors must be improved to remove the striping pattern caused by the inappropriate adjustment of radiometric values. 2) The projected ground pixel size of 20 x 20m was degraded by some unknown factors and the actual resolution of the MOMS data is much larger than the projected 20m ground size. For the time being, the geoscientific applications of the MOMS data are rather limited.

  7. YB-1 overexpression promotes a TGF-β1-induced epithelial–mesenchymal transition via Akt activation

    SciTech Connect

    Ha, Bin; Lee, Eun Byul; Cui, Jun; Kim, Yosup; Jang, Ho Hee

    2015-03-06

    The Y-box binding protein-1 (YB-1) is a transcription/translation regulatory protein, and the expression thereof is associated with cancer aggressiveness. In the present study, we explored the regulatory effects of YB-1 during the transforming growth factor-β1 (TGF-β1)-induced epithelial-to-mesenchymal transition (EMT) in lung adenocarcinoma cells. Downregulation of YB-1 increased E-cadherin promoter activity, and upregulation of YB-1 decreased promoter activity, suggesting that the YB-1 level may be correlated with the EMT. TGF-β1 induced YB-1 expression, and TGF-β1 translocated cytosolic YB-1 into the nucleus. YB-1 overexpression promoted TGF-β1-induced downregulation of epithelial markers, upregulation of mesenchymal markers, and cell migration. Moreover, YB-1 overexpression enhanced the expression of E-cadherin transcriptional repressors via TGF-β1-induced Akt activation. Our findings afford new insights into the role played by YB-1 in the TGF-β1 signaling pathway. - Highlights: • YB-1 regulates E-cadherin expression in A549 cells. • TGF-β1 induces upregulating and nuclear localization of YB-1. • YB-1 overexpression accelerates TGF-β1-induced EMT and cell migration. • YB-1 regulates Snail and Slug expression via Akt activation.

  8. Spectrum and energy levels of the Yb4+ free ion (Yb V)

    NASA Astrophysics Data System (ADS)

    Meftah, Ali; Wyart, Jean-François; Tchang-Brillet, Wan-Ü. Lydia; Blaess, Christophe; Champion, Norbert

    2013-10-01

    The spectrum of ionized ytterbium produced by a sliding spark source was recorded on the 10 m high resolution vacuum ultraviolet normal-incidence spectrograph of the Meudon Observatory. About 1080 lines attributed to Yb V, hitherto unknown, have been identified. The analysis of this spectrum established all the energy levels of the ground configuration 4f12 and, respectively 174, 12 and 43 levels of the excited configurations 4f115d,4f116s and 4f116p. The theoretical calculations by means of the Cowan codes included a least-squares optimization of the relevant radial parameters by minimizing the differences between calculated and experimental level energies, which led to mean errors of 55 cm-1 for the 56 even parity levels and 51 cm-1 for the 186 odd parity ones. Interactions with the unknown core-excited configurations 5p54f13, 5p54f126p, 5p54f125d and 5p54f126s were taken into account.

  9. Physical properties and superconductivity of skutterudite-related Yb3Co4.3Sn12.7 and Yb3Co4Ge13

    NASA Astrophysics Data System (ADS)

    Mudryk, Ya; Grytsiv, A.; Rogl, P.; Dusek, C.; Galatanu, A.; Idl, E.; Michor, H.; Bauer, E.; Godart, C.; Kaczorowski, D.; Romaka, L.; Bodak, O.

    2001-08-01

    Rietveld analysis was performed for the intermetallics Yb3Co4.3Sn12.7 and Yb3Co4Ge13 crystallizing with the closely related structure types, Yb3Rh4Sn13 and Yb3Co4Ge13. Below Tc = 3.4 K Yb3Co4.3Sn12.7 crosses over into a type-II superconducting ground state with Hc2(0)~2.5 T. Yb3Co4Ge13 stays in the normal state down to 300 mK. The γ value of 2.3(2) mJ gat-1 K-2 and the Debye temperature ΘD = 207(5) K deduced from the specific heat as well as Tc correspond to that of elementary Sn, thus indicating conventional BCS superconductivity. Hydrostatic pressure applied to Yb3Co4.3Sn12.7 reveals both an overall decrease of the absolute resistivity values, as well as a decrease of Tc, which vanishes for a critical pressure below 10 kbar. The magnetoresistance of both Yb-based compounds is positive at low temperature but does not exceed 8% in fields of 12 T. The Seebeck coefficient has a maximum value of about 18 µV K-1 at T~250 K. LIII and magnetic susceptibility measurements reveal intermediate valence: 2.66(3) and 2.18(3) for Yb3Co4Ge13 and Yb3Co4.3Sn12.7, respectively.

  10. Comparative 3-D Modeling of tmRNA

    PubMed Central

    Burks, Jody; Zwieb, Christian; Müller, Florian; Wower, Iwona; Wower, Jacek

    2005-01-01

    Background Trans-translation releases stalled ribosomes from truncated mRNAs and tags defective proteins for proteolytic degradation using transfer-messenger RNA (tmRNA). This small stable RNA represents a hybrid of tRNA- and mRNA-like domains connected by a variable number of pseudoknots. Comparative sequence analysis of tmRNAs found in bacteria, plastids, and mitochondria provides considerable insights into their secondary structures. Progress toward understanding the molecular mechanism of template switching, which constitutes an essential step in trans-translation, is hampered by our limited knowledge about the three-dimensional folding of tmRNA. Results To facilitate experimental testing of the molecular intricacies of trans-translation, which often require appropriately modified tmRNA derivatives, we developed a procedure for building three-dimensional models of tmRNA. Using comparative sequence analysis, phylogenetically-supported 2-D structures were obtained to serve as input for the program ERNA-3D. Motifs containing loops and turns were extracted from the known structures of other RNAs and used to improve the tmRNA models. Biologically feasible 3-D models for the entire tmRNA molecule could be obtained. The models were characterized by a functionally significant close proximity between the tRNA-like domain and the resume codon. Potential conformational changes which might lead to a more open structure of tmRNA upon binding to the ribosome are discussed. The method, described in detail for the tmRNAs of Escherichia coli, Bacillus anthracis, and Caulobacter crescentus, is applicable to every tmRNA. Conclusion Improved molecular models of biological significance were obtained. These models will guide in the design of experiments and provide a better understanding of trans-translation. The comparative procedure described here for tmRNA is easily adopted for the modeling the members of other RNA families. PMID:15958166

  11. Simultaneously optimizing fluorescent and paramagnetic properties of bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning

    SciTech Connect

    Wu, Xiaofeng; Hu, Shigang; Tan, Congbing; Liu, Yunxin

    2015-04-15

    Graphical abstract: Crystal field tuning is a powerful approach for simultaneously enhancing the optical and magnetic properties of lanthanide-doped NaGdF{sub 4} bi-functional nanocrystals. - Abstract: Here, we show the simultaneous enhancement of fluorescent and paramagnetic properties in bifunctional NaGdF{sub 4}:Yb{sup 3+}/Er{sup 3+} nanocrystals by crystal field tuning. The energy level splitting calculation indicates, that lanthanide ionic pairs La{sup 3+}/Lu{sup 3+} introduced into the NaGdF{sub 4} host can modify the crystal field around emitters (e.g., Er{sup 3+} and Tm{sup 3+}) and sensitizers (e.g., Yb{sup 3+}) that result in the broadening of crystal field splitting of energy levels and the abundant multi-site distribution of upconversion luminescence. The optimization of the paramagnetic properties in NaGdF{sub 4} doped with emitters and sensitizers is ascribed to the lowering of anti-ferromagnetic coupling.

  12. 78 FR 28258 - mPower\\TM\\ Design-Specific Review Standard

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-05-14

    ... COMMISSION mPower\\TM\\ Design-Specific Review Standard AGENCY: Nuclear Regulatory Commission. ACTION: Design-Specific Review Standard (DSRS) for the mPower\\TM\\ Design; request for comment. SUMMARY: The U.S. Nuclear... the mPower\\TM\\ design (mPower\\TM\\ DSRS). The purpose of the mPower\\TM\\ DSRS is to more fully...

  13. Crystallization of BaF2-ZnF2-YbF3-ThF4 glass

    NASA Technical Reports Server (NTRS)

    Garcia, Roberto; Doremus, Robert H.; Ko, Sen-Hou; Margraf, Tracey; Bansal, Narottam P.

    1988-01-01

    The phases and the rates of crystallization in a Ba-Zn-Yb-Th fluoride glass were studied using differential scanning calorimetry, XRD, and observational and chemical SEM analyses. The crystallizing phases that were identified included a BaYbTh fluoride, ZnF2, and YbF3. The BaYbTh fluoride crystallized first at about 450 C, and ZnF2, which was excluded from this phase, crystallized at its surfaces. At higher temperatures, the BaYbTh fluoride phase decomposed partially to BaThF6 and YbF3 phases.

  14. Governance in EU illicit drugs policy.

    PubMed

    Edwards, Carel; Galla, Maurice

    2014-09-01

    This commentary represents the authors' views on EU governance in illicit drug policy, a field in which they were active for more than 10 years between them. EU drug policy has a narrow legal basis in the European Treaties and is mostly non-binding. The main policy instruments are 8-year EU Drug Strategies, underpinned by 4-year Action Plans which set out specific objectives at national, EU or international level. The approach that guides EU drug policy is known as the 'balanced approach'. It is remarkably restrained and reflects the reality that very few Member States have either the socio-political culture or the resources to consistently apply the punitive sanctions foreseen by the UN conventions. An important feature of EU governance in the field of drugs is the proactive support that is provided to non-governmental organisations both within the EU as well as in accession, associated or third countries. At a global level, the EU is a major financial aid donor also in this field. This position is not however reflected in corresponding political clout for the EU within the UN system. EU governance on drugs has made it possible for many of its Member States to accommodate the problem rather than to "solve" what by all the evidence from the last 100 years may well be insoluble, at least by means of criminalisation and prohibition. The big question is where EU drug policy is headed in the next few years. The EU has been promoting measures and practices that target real problems. It has done so without indulging too much in unhelpful rhetoric. However, like all successful formulae this one also has a sell-by date. EU governance in the field of drugs cannot afford to stand still. It needs to find a second wind.

  15. Thermal quenching of photoluminescence of Eu3+ ions in an Eu(fod)3 complex

    NASA Astrophysics Data System (ADS)

    Gerasimova, V. I.; Zavorotnyi, Yu. S.; Rybaltovskii, A. O.; Taraeva, A. Yu.

    2006-05-01

    We have studied the photoluminescence (PL) spectra of Eu3+ ions in the complex Eu(fod)3 (fod = 6,6,7,7,8,8,8-heptafluoro-2,2-dimethyl-3,5-octadione) and also in polymers doped with Eu(fod)3 with the help of supercritical carbon dioxide. We have established that in the temperature range 20°C 100°C, we observe thermal quenching of the photoluminescence of Eu3+ ions, and this quenching is most efficient in polycrystalline Eu(fod)3 powder and Eu(fod)3-doped polypropylene.

  16. Diffusion of Excitation in GGG:Yb3+ Laser Crystal

    NASA Astrophysics Data System (ADS)

    Kisialiou, I. G.; Ivakin, E. V.

    2015-01-01

    The excitation diffusion coefficient DE is measured directly in laser crystals by the optical method of high-frequency dynamic gratings. DE for Gd3Ga5O12:Yb3+ (21 at.%) crystal is found to be 3·10-9 cm3/s at room temperature and 1.2·10-8 cm3/s at 190°C. In KYW:Yb3+ (20 at.%) crystal no excitation diffusion is observed under the same experimental conditions. It is shown that DE is affected by the activator concentration, the temperature, and the probability of radiationless energy exchange between neighboring active impurity ions, which depends on the minimal distance between donor and acceptor.

  17. Social Stories[TM] for Children with Disabilities

    ERIC Educational Resources Information Center

    Reynhout, Georgina; Carter, Mark

    2006-01-01

    A review of the empirical research literature on Social Stories[TM] is presented, including a descriptive review and single-subject meta-analysis of appropriate studies. Examination of data suggests the effects of Social Stories[TM] are highly variable. Interpretations of extant studies are frequently confounded by inadequate participant…

  18. Social Stories[TM]: A Possible Theoretical Rationale

    ERIC Educational Resources Information Center

    Reynhout, Georgina; Carter, Mark

    2011-01-01

    Social Stories[TM] are an intervention widely used with individuals with autism spectrum disorders (ASD). This paper discusses a possible theoretical rationale that might account for the purported efficacy of Social Stories[TM]. Attributes of individuals with ASD in relation to Social Story intervention including difficulties with theory of mind…

  19. Accelerated Reader[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2010

    2010-01-01

    "Accelerated Reader"[TM] is a guided reading intervention used to supplement regular reading instruction in K-12 classrooms. Its aim is to improve students' reading skills through reading practice and quizzes on the books students read. The "Accelerated Reader"[TM] program calls for students to select and read a book and then take a computerized…

  20. Utilising eduroam[TM] Architecture in Building Wireless Community Networks

    ERIC Educational Resources Information Center

    Huhtanen, Karri; Vatiainen, Heikki; Keski-Kasari, Sami; Harju, Jarmo

    2008-01-01

    Purpose: eduroam[TM] has already been proved to be a scalable, secure and feasible way for universities and research institutions to connect their wireless networks into a WLAN roaming community, but the advantages of eduroam[TM] have not yet been fully discovered in the wireless community networks aimed at regular consumers. This aim of this…

  1. Accelerated Math[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2010

    2010-01-01

    "Accelerated Math"[TM], published by Renaissance Learning, is a software tool used to customize assignments and monitor progress in mathematics for students in grades 1-12. "Accelerated Math"[TM] creates individualized assignments that align with state standards and national guidelines, scores student work, and generates formative feedback through…

  2. SpellRead[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2013

    2013-01-01

    "SpellRead"[TM], formerly known as "SpellRead Phonological Auditory Training"[R], is a small-group literacy program for struggling readers in grades 2-12. "SpellRead"[TM] integrates the auditory and visual aspects of the reading process and emphasizes specific skill mastery through systematic and explicit instruction. Students are taught to…

  3. Accelerated Math[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2011

    2011-01-01

    "Accelerated Math"[TM], published by Renaissance Learning, is a software tool used to customize assignments and monitor progress in math for students in grades 1-12. The "Accelerated Math"[TM] software creates individualized assignments aligned with state standards and national guidelines, scores student work, and generates reports on student…

  4. 75 FR 61479 - Western Passage OCGenTM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Energy Regulatory Commission Western Passage OCGen\\TM\\ Power Project; Notice of Preliminary Permit... permit, pursuant to section 4(f) of the Federal Power Act, proposing to study the feasibility of the Western Passage OCGen\\TM\\ Power Project, located in Western Passage, in the vicinity of the City...

  5. 75 FR 61480 - Cobscook Bay OCGenTM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-05

    ... Energy Regulatory Commission Cobscook Bay OCGen\\TM\\ Power; Notice of Preliminary Permit Application..., pursuant to section 4(f) of the Federal Power Act, proposing to study the feasibility of the Cobscook Bay OCGen\\TM\\ Power Project, located in the Cobscook Bay, near the City of Eastport, Washington...

  6. Disability Awareness Night[TM]: 2006 Honorees, Sponsors, Teams

    ERIC Educational Resources Information Center

    Exceptional Parent, 2006

    2006-01-01

    This article presents the 2006 honorees, sponsors, and teams for the Disability Awareness Night[TM]. Disability Awareness Night[TM] is a unique and powerful community outreach program. Its vision is to continue to raise awareness outside of the community of individuals with disabilities to continue the goal that this program will open doors to…

  7. Full Immersive Virtual Environment Cave[TM] in Chemistry Education

    ERIC Educational Resources Information Center

    Limniou, M.; Roberts, D.; Papadopoulos, N.

    2008-01-01

    By comparing two-dimensional (2D) chemical animations designed for computer's desktop with three-dimensional (3D) chemical animations designed for the full immersive virtual reality environment CAVE[TM] we studied how virtual reality environments could raise student's interest and motivation for learning. By using the 3ds max[TM], we can visualize…

  8. Doors to Discovery[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2007

    2007-01-01

    "Doors to Discovery"[TM] is an early childhood curriculum that uses thematic units to engage young children and support them as they build an understanding of their world. "Doors to Discovery"[TM] literacy activities are used to encourage children's development in a number of areas identified by research as the foundation for early literacy…

  9. Relative radiometric calibration of LANDSAT TM reflective bands

    NASA Technical Reports Server (NTRS)

    Barker, J. L.

    1984-01-01

    A common scientific methodology and terminology is outlined for characterizing the radiometry of both TM sensors. The magnitude of the most significant sources of radiometric variability are discussed and methods are recommended for achieving the exceptional potential inherent in the radiometric precision and accuracy of the TM sensors.

  10. Inside Linden Lab: Second Life [TM] for Educators

    ERIC Educational Resources Information Center

    Atkinson, Tom

    2008-01-01

    A new culture called Second Life [TM] has emerged that promises innovative strategies for everything from social interactions to business. Some educators believe it may hold new and unique opportunities for teaching and learning. Second Life [TM] (SL) is the creation of Linden Labs, a San Francisco-based corporation defined by its creators as "an…

  11. Water quality mapping using Landsat TM imagery

    NASA Astrophysics Data System (ADS)

    Lim, H. S.; MatJafri, M. Z.; Abdullah, K.; Alias, A. N.; Wong, C. J.; Mustapha-Rosli, M. R.; Mohd Saleh, N.

    2009-05-01

    Environmental monitoring through the method of traditional ship sampling is time consuming and requires a high survey cost. The objective of this study is to evaluate the feasibility of Landsat TM imagery for total suspended solids (TSS) mapping using a newly developed algorithm over Penang Island. The study area is the seawater region around Penang Island, Malaysia. Water samples were collected during a 3-hour period simultaneously with the satellite image acquisition and later analyzed in the laboratory above the study area. The samples locations were determined using a handheld GPS. The satellite image was geometrically corrected using the second order polynomial transformation. The satellite image also was atmospheric corrected by using ATCOR2 image processing software. The digital numbers for each band corresponding to the sea-truth locations were extracted and then converted into reflectance values for calibration of the water quality algorithm. The proposed algorithm is based on the reflectance model that is a function of the inherent optical properties of water, which can be related to its constituent's concentrations. The generated algorithm was developed for three visible wavelenghts, red, green and blue for this study. Results indicate that the proposed developed algorithm was superior based on the correlation coefficient (R) and root-mean-square deviation (RMS) values. Finally the proposed algorithm was used for TSS mapping at Penang Island, Malaysia. The generated TSS map was colour-coded for visual interpretation and image smoothing was performed on the map to remove random noise. This preliminary study has produced a promising result. This study indicates that the empirical algorithm is suitable for TSS mapping around Penang Island by using satellite Landsat TM data.

  12. Blue laser cooling transitions in Tm I

    NASA Astrophysics Data System (ADS)

    Kolachevsky, N.; Akimov, A.; Tolstikhina, I.; Chebakov, K.; Sokolov, A.; Rodionov, P.; Kanorski, S.; Sorokin, V.

    2007-12-01

    We have studied possible candidates for laser cooling transitions in 169Tm in the spectral region of 410-420 nm. By means of saturation absorption spectroscopy, we have measured the hyperfine structure and rates of two nearly closed cycling transitions from the ground state 4f136s2(2F0)(Jg=7/2) to upper states 4f12(3H5)5d3/26s2(Je=9/2) at 410.6 nm and 4f12(3F4)5d5/26s2(Je=9/2) at 420.4 nm and evaluated the life times of the excited levels as 15.9(8) ns and 48(6) ns, respectively. Decay rates from these levels to neighboring opposite-parity levels are evaluated by means of Hartree-Fock calculations. We conclude that the strong transition at 410.6 nm has an optical leak rate of less then 2×10-5 and can be used for efficient laser cooling of 169Tm from a thermal atomic beam. The hyperfine structure of two other even-parity levels, which can be excited from the ground state at 409.5 nm and 418.9 nm, is also measured by the same technique. In addition, we give a calculated value of 7(2) s-1 for the rate of magnetic-dipole transition at 1.14 μm between the fine structure levels (Jg=7/2)↔(J’g=5/2) of the ground state which can be considered as a candidate for applications in atomic clocks.

  13. Efficient lasing in Yb:(YLa)2O3 ceramics

    NASA Astrophysics Data System (ADS)

    Snetkov, I. L.; Mukhin, I. B.; Balabanov, S. S.; Permin, D. A.; Palashov, O. V.

    2015-02-01

    A high-optical-quality sample of Yb0.1Y1.7La0.2O3 ceramics is prepared using a recently developed technique of selfpropagating high-temperature synthesis of rare-earth-doped yttrium oxide nanopowder from acetate - nitrates of metals. Its optical and spectral characteristics are studied, and quasi-cw lasing at a wavelength of 1033 nm is achieved with a power of 7 W and a slope efficiency of 25%.

  14. Differential Control of Interleukin-6 mRNA Levels by Cellular Distribution of YB-1

    PubMed Central

    Kang, Sujin; Lee, Taeyun A.; Ra, Eun A.; Lee, Eunhye; Choi, Hyun jin; Lee, Sungwook; Park, Boyoun

    2014-01-01

    Cytokine production is essential for innate and adaptive immunity against microbial invaders and must be tightly controlled. Cytokine messenger RNA (mRNA) is in constant flux between the nucleus and the cytoplasm and in transcription, splicing, or decay; such processes must be tightly controlled. Here, we report a novel function of Y-box-binding protein 1 (YB-1) in modulating interleukin-6 (IL-6) mRNA levels in a cell type-specific manner. In lipopolysaccharide (LPS)-stimulated macrophages, YB-1 interacts with IL-6 mRNA and actively transports it to the extracellular space by YB-1-enriched vesicles, resulting in the proper maintenance of intracellular IL-6 mRNA levels. YB-1 secretion occurs in a cell type-specific manner. Whereas macrophages actively secret YB-1, dendritic cells maintain it predominantly in the cytoplasm even in response to LPS. Intracellular YB-1 has the distinct function of regulating IL-6 mRNA stability in dendritic cells. Moreover, because LPS differentially regulates the expression of histone deacetylase 6 (HDAC6) in macrophages and dendritic cells, this stimulus might control YB-1 acetylation differentially in both cell types. Taken together, these results suggest a unique feature of YB-1 in controlling intracellular IL-6 mRNA levels in a cell type-specific manner, thereby leading to functions that are dependent on the extracellular and intracellular distribution of YB-1. PMID:25398005

  15. Yb-based heavy fermion compounds and field tuned quantum chemistry

    SciTech Connect

    Mun, Eundeok

    2010-01-01

    The motivation of this dissertation was to advance the study of Yb-based heavy fermion (HF) compounds especially ones related to quantum phase transitions. One of the topics of this work was the investigation of the interaction between the Kondo and crystalline electric field (CEF) energy scales in Yb-based HF systems by means of thermoelectric power (TEP) measurements. In these systems, the Kondo interaction and CEF excitations generally give rise to large anomalies such as maxima in ρ(T) and as minima in S(T). The TEP data were use to determine the evolution of Kondo and CEF energy scales upon varying transition metals for YbT2Zn20 (T = Fe, Ru, Os, Ir, Rh, and Co) compounds and applying magnetic fields for YbAgGe and YbPtBi. For YbT2Zn20 and YbPtBi, the Kondo and CEF energy scales could not be well separated in S(T), presumably because of small CEF level splittings. A similar effect was observed for the magnetic contribution to the resistivity. For YbAgGe, S(T) has been successfully applied to determine the Kondo and CEF energy scales due to the clear separation between the ground state and thermally excited CEF states. The Kondo temperature, TK, inferred from the local maximum in S(T), remains finite as magnetic field increases up to 140 kOe. In this dissertation we have examined the heavy quasi-particle behavior, found near the field tuned AFM quantum critical point (QCP), with YbAgGe and YbPtBi. Although the observed nFL behaviors in the vicinity of the QCP are different between YbAgGe and YbPtBi, the constructed H-T phase diagram including the two crossovers are similar. For both YbAgGe and YbPtBi, the details of the quantum criticality turn out to be complicated. We expect that YbPtBi will provide an additional example of field tuned quantum criticality, but clearly there are further experimental investigations left and more ideas needed to understand the basic physics of field-induced quantum

  16. Valence state change and defect centers induced by infrared femtosecond laser in Yb:YAG crystals

    SciTech Connect

    Wang, Xinshun Liu, Yang; Zhao, Panjuan; Guo, Zhongyi; Li, Yan; Qu, Shiliang

    2015-04-21

    The broad band upconversion luminescence in Yb{sup 3+}:YAG crystal has been observed in experiments under the irradiation of focused infrared femtosecond laser. The dependence of the fluorescence intensity on the pump power shows that the upconversion luminescence is due to simultaneous two-photon absorption process, which indicates that the broad emission bands at 365 and 463 nm could be assigned to the 5d → 4f transitions of Yb{sup 2+} ions and the one at 692 nm could be attributed to the electron-hole recombination process on (Yb{sup 2+}-F{sup +}) centers. The absorption spectra of the Yb:YAG crystal samples before and after femtosecond laser irradiation, and after further annealing reveal that permanent valence state change of Yb ions from Yb{sup 3+} to Yb{sup 2+} and (Yb{sup 2+}-F{sup +}) centers have been induced by infrared femtosecond laser irradiation in Yb{sup 3+}:YAG crystal.

  17. Nuclear YB-1 expression as a negative prognostic marker in nonsmall cell lung cancer.

    PubMed

    Gessner, C; Woischwill, C; Schumacher, A; Liebers, U; Kuhn, H; Stiehl, P; Jürchott, K; Royer, H D; Witt, C; Wolff, G

    2004-01-01

    The human Y-box binding protein, YB-1, is a multifunctional protein that regulates gene expression. Nuclear expression of YB-1 has been associated with chemoresistance and poor prognosis of tumour patients. Representative samples from autopsied material of primary tumours from 77 patients with NSCLC were investigated by immunohistochemistry for subcellular distribution of YB-1 and p53, in order to evaluate the prognostic role of nuclear expression of YB-1. Cytoplasmic YB-1 expression was found in all tumour samples, whereas nuclear expression was only observed in 48%. There was no correlation with histological classification, clinical parameters or tumour size, stage and metastasis status. However, patients with positive nuclear YB-1 expression in tumours showed reduced survival times when compared with patients without nuclear expression. Including information about the histology and mutational status for p53 increased the prognostic value of nuclear YB-1. Patients with nuclear YB-1 expression and p53 mutations had the worst prognosis (median survival 3 months), while best outcome was found in patients with no nuclear YB-1 and wildtype p53 (median survival 15 months). This suggests that the combined analysis of both markers allows a better identification of subgroups with varying prognosis. Nuclear expression of Y-box binding protien seems to be an independent prognostic marker.

  18. Spectroscopy of 155Yb: Structure evolution in the N =85 isotones

    NASA Astrophysics Data System (ADS)

    Li, X. Q.; Xu, C.; Zhang, S. Q.; Hua, H.; Meng, J.; Bark, R. A.; Chen, Q. B.; Niu, C. Y.; Han, R.; Wyngaardt, S. M.; Wang, S. Y.; Wang, S.; Qi, B.; Liu, L.; Zhu, L. H.; Shi, Z.; Zhang, G. L.; Sun, B. H.; Le, X. Y.; Song, C. Y.; Ye, Y. L.; Jiang, D. X.; Xu, F. R.; Li, Z. H.; Sun, J. J.; Shi, Y.; Zhao, P. W.; Liang, W. Y.; Li, C. G.; Wang, C. G.; Chen, X. C.; Li, Z. H.; Sun, D. P.; Liu, C.; Li, Z. Q.; Jones, P.; Lawrie, E. A.; Lawrie, J. J.; Wiedeking, M.; Bucher, T. D.; Dinoko, T.; Kheswa, B. V.; Makhathini, L.; Majola, S. N. T.; Ndayishimye, J.; Noncolela, S. P.; Shirinda, O.; Gál, J.; Kalinka, G.; Molnár, J.; Nyakó, B. M.; Timár, J.; Juhász, K.; Arogunjo, M.

    2016-08-01

    High-spin states in 155Yb have been studied via the 144Sm(16O,5 n )155Yb reaction at a beam energy of 118 MeV. One negative-parity and one positive-parity cascade built on the ν f7 /2 and ν i13 /2 states, respectively, are established for the first time. The structures observed in 155Yb are compared with those in the neighboring N =85 isotones and with semiempirical shell-model (SESM) calculations. According to adiabatic and configuration-fixed constrained triaxial covariant density functional theory (CDFT) calculations, a coexistence of prolate and oblate shapes is predicted to exist in 155Yb.

  19. X-RAY ABSORPTION SPECTROSCOPY OF YB3+-DOPED OPTICAL FIBERS

    SciTech Connect

    Citron, Robert; Kropf, A.J.

    2008-01-01

    Optical fibers doped with Ytterbium-3+ have become increasingly common in fiber lasers and amplifiers. Yb-doped fibers provide the capability to produce high power and short pulses at specific wavelengths, resulting in highly effective gain media. However, little is known about the local structure, distribution, and chemical coordination of Yb3+ in the fibers. This information is necessary to improve the manufacturing process and optical qualities of the fibers. Five fibers doped with Yb3+ were studied using Extended X-ray Absorption Fine Structure (EXAFS) spectroscopy and X-ray Absorption Near Edge Spectroscopy (XANES), in addition to Yb3+ mapping. The Yb3+ distribution in each fiber core was mapped with 2D and 1D intensity scans, which measured X-ray fluorescence over the scan areas. Two of the five fibers examined showed highly irregular Yb3+ distributions in the core center. In four of the five fibers Yb3+ was detected outside of the given fiber core dimensions, suggesting possible Yb3+ diffusion from the core, manufacturing error, or both. X-ray absorption spectroscopy (XAS) analysis has so far proven inconclusive, but did show that the fibers had differing EXAFS spectra. The Yb3+ distribution mapping proved highly useful, but additional modeling and examination of fiber preforms must be conducted to improve XAS analysis, which has been shown to have great potential for the study of similar optical fi bers.

  20. The Yb-doped aluminosilicate fibers photodarkening mechanism based on the charge-transfer state excitation

    NASA Astrophysics Data System (ADS)

    Rybaltovsky, A. A.; Bobkov, K. K.; Velmiskin, V. V.; Umnikov, A. A.; Shestakova, I. A.; Guryanov, A. N.; Likhachev, M. E.; Bubnov, M. M.; Dianov, E. M.

    2014-03-01

    We have studied the photodarkening effect in fiber preforms with an ytterbium-doped aluminosilicate glass core. The room-temperature stable Yb2+ ions formation in the glass matrix under both UV- and NIR-pumping irradiation was revealed by the method of absorption spectra analysis and the fluorescence spectroscopy technique. Comparative studies of preforms and crystals samples luminescence spectra, obtained under UV-excitation, were performed. A general mechanism of Yb2+ ions and aluminium oxygen-hole centers (Al-OHC) formation as a result of photoinduced process of Yb3+ ions excitation to "charge-transfer state" (CTS) was found for both Yb:YAG crystal and aluminosilicate glass.

  1. Thermoluminescence properties of ZnO and ZnO:Yb nanophosphors

    SciTech Connect

    Pal, U.; Melendrez, R.; Chernov, V.; Barboza-Flores, M.

    2006-10-30

    ZnO and ZnO:Yb thermoluminescence nanophosphors have been developed and tested under beta radiation. Spherical nanoparticles of sizes ranging from 130 to 1200 nm were prepared through a glycol mediated chemical synthesis. The Yb doping had a thermoluminescence quenching effect compared to undoped ZnO. The 5% Yb concentration produced a low fading, a single thermoluminescence glow peak structure, and a dose linearity behavior adequate for thermoluminescence dosimetry applications. The ZnO:Yb nanophosphor has a great potential as a dosimeter for monitoring in ionizing radiation fields.

  2. Quasi-millimeter-wave absorption behavior in Y/Yb-stabilized zirconia ceramics

    NASA Astrophysics Data System (ADS)

    Teranishi, Takashi; Akiyama, Naoki; Ayano, Keiko; Hayashi, Hidetaka; Kishimoto, Akira; Fujimori, Kazuhiro; Hoshina, Takuya; Takeda, Hiroaki; Tsurumi, Takaaki

    2012-06-01

    Broadband dielectric spectra from 10 to 1014 Hz were acquired for 8 mol. % Y2O3/Yb2O3-stabilized zirconia (8YSZ and 8YbSZ) ceramics that related the dipole and ionic polarization losses to the absorption efficiency of electromagnetic irradiation. For 24 GHz irradiation, 8YSZ exhibited a higher absorption efficiency than 8YbSZ, resulting in a higher dielectric loss. The difference in the dielectric loss was interpreted as the difference in the loss of the dipoles originating from the fluctuations in the defect associations (Y'ZrVo ¨ and Yb'ZrVo ¨).

  3. Interplay between YB-1 and IL-6 promotes the metastatic phenotype in breast cancer cells

    PubMed Central

    Castellana, Bàrbara; Aasen, Trond; Moreno-Bueno, Gema; Dunn, Sandra E.; Ramón y Cajal, Santiago

    2015-01-01

    Epithelial to mesenchymal transition (EMT) induces cell plasticity and promotes metastasis. The multifunctional oncoprotein Y-box binding protein-1 (YB-1) and the pleiotropic cytokine interleukin 6 (IL-6) have both been implicated in tumor cell metastasis and EMT, but via distinct pathways. Here, we show that direct interplay between YB-1 and IL-6 regulates breast cancer metastasis. Overexpression of YB-1 in breast cancer cell lines induced IL-6 production while stimulation with IL-6 increased YB-1 expression and YB-1 phosphorylation. Either approach was sufficient to induce EMT features, including increased cell migration and invasion. Silencing of YB-1 partially reverted the EMT and blocked the effect of IL-6 while inhibition of IL-6 signaling blocked the phenotype induced by YB-1 overexpression, demonstrating a clear YB-1/IL-6 interdependence. Our findings describe a novel signaling network in which YB-1 regulates IL-6, and vice versa, creating a positive feed-forward loop driving EMT-like metastatic features during breast cancer progression. Identification of signaling partners or pathways underlying this co-dependence may uncover novel therapeutic opportunities. PMID:26512918

  4. Renal threshold phosphate concentration (TmPO4/GFR).

    PubMed Central

    Kruse, K; Kracht, U; Göpfert, G

    1982-01-01

    The ratio of maximum rate of renal tubular reabsorption of phosphate to glomerular filtration rate (TmPO4/GFR) was determined in 546 schoolchildren, aged between 6 and 17.9 years, using the nomogram of Walton and Bijvoet.1 TmPO4/GFR correlated with chronological age in girls and boys and in each remained significantly higher than in adults. TmPO4/GFR in the children correlated neither with fasting serum immunoreactive calcitonin and parathyroid hormone levels nor with the urinary cyclic AMP excretion. The study showed a parallel decrease in TmPO4/GFR, excretion of total hydroxyproline and serum alkaline phosphatase activities after puberty, with a significant relationship of both these indices of bone turnover to TmPO4/GFR values. This indicates that the high renal phosphate threshold of children may be an important factor for bone mineralisation by providing high extracellular inorganic phosphate concentrations during normal growth. PMID:6280622

  5. Interfacial effects in Fe/4d TM multilayers (abstract)

    SciTech Connect

    Tomaz, M.A.; Antel, W.J., Jr.; Harp, G.R.; OBrien, W.L.

    1997-04-01

    We have studied Fe/TM multilayers (TM=Mo, Nb, Ru, Rh, Pd) using x-ray magnetic circular dischroism, magneto-optical Kerr effect, and x-ray diffraction. A diverse set of magnetic behaviors emerges from the analysis. We focus on the behavior which can be attributed to the existence of a physical interface between different chemical species. In particular, we have measured an enhanced Fe moment in some cases (TM=Ru, Mo, Rh, Pd) yet not in others (TM=Nb). These results will be discussed, including the relative orbital and spin moments and the effects of alloying at the interface. The measured induced moments in the TM layer will be presented as well where applicable. {copyright} {ital 1997 American Institute of Physics.}

  6. Comparison of classification schemes for MSS and TM data

    NASA Technical Reports Server (NTRS)

    Anuta, P. E.; Bartolucci, L. A.; Lozano-Garcia, D. F.; Valdes, J. A.; Valenzuela, C. R.

    1984-01-01

    The launch of the Landsat-4 satellite in July 1982 provided the first full coverage from space of the 0.4-12 micron spectrum of the earth scene. In addition to the green, red, and near IR bands of the MSS, the TM provides a band in the blue, two in the middle IR, and one thermal IR. The paper describes spectral class analysis of coincident MSS and TM data to evaluate the contribution of the additional TM bands. In addition, various classifiers are available which were applied to the TM data. In the spectral class analysis, twice the number of separable classes was found in the TM data compared to the MSS data.

  7. Charge transfer in cold Yb++Rb collisions

    NASA Astrophysics Data System (ADS)

    Sayfutyarova, Elvira R.; Buchachenko, Alexei A.; Yakovleva, Svetlana A.; Belyaev, Andrey K.

    2013-05-01

    Charge-transfer cold Yb++ Rb collision dynamics is investigated theoretically using high-level ab initio potential energy curves, dipole moment functions, and nonadiabatic coupling matrix elements. Within the scalar-relativistic approximation, the radiative transitions from the entrance A1Σ+ to the ground X1Σ+ state are found to be the only efficient charge-transfer pathway. The spin-orbit coupling does not open other efficient pathways, but alters the potential energy curves and the transition dipole moment for the A-X pair of states. The radiative, as well as the nonradiative, charge-transfer cross sections calculated within the 10-3-10 cm-1 collision energy range exhibit all features of the Langevin ion-atom collision regime, including a rich structure associated with centrifugal barrier tunneling (orbiting) resonances. Theoretical rate coefficients for two Yb isotopes agree well with those measured by immersing Yb+ ions in an ultracold Rb ensemble in a hybrid trap. Possible origins of discrepancy in the product distributions and relations to previously studied similar processes are discussed.

  8. Comparative toxicity of nanoparticulate/bulk Yb₂O₃ and YbCl₃ to cucumber (Cucumis sativus).

    PubMed

    Zhang, Peng; Ma, Yuhui; Zhang, Zhiyong; He, Xiao; Guo, Zhi; Tai, Renzhong; Ding, Yayun; Zhao, Yuliang; Chai, Zhifang

    2012-02-01

    With the increasing utilization of nanomaterials, there is a growing concern for the potential environmental and health effects of them. To assess the environmental risks of nanomaterials, better knowledge about their fate and toxicity in plants are required. In this work, we compared the phytotoxicity of nanoparticulate Yb(2)O(3), bulk Yb(2)O(3), and YbCl(3)·6H(2)O to cucumber plants. The distribution and biotransformation of the three materials in plant roots were investigated in situ by TEM, EDS, as well as synchrotron radiation based methods: STXM and NEXAFS. The decrease of biomass was evident at the lowest concentration (0.32 mg/L) when exposed to nano-Yb(2)O(3), while at the highest concentration, the most severe inhibition was from YbCl(3). The inhibition was dependent on the actual amount of toxic Yb uptake by the cucumber plants. In the intercellular regions of the roots, Yb(2)O(3) particles and YbCl(3) were all transformed to YbPO(4). We speculate that the dissolution of Yb(2)O(3) particles induced by the organic acids exuded from roots played an important role in the phytotoxicity. Only under the nano-Yb(2)O(3) treatment, YbPO(4) deposits were found in the cytoplasm of root cells, so the phytotoxicity might also be attributed to the Yb internalized into the cells.

  9. 76 FR 38618 - Proposed Information Collection; Comment Request; StormReadyTM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-07-01

    ...Ready\\TM\\, TsunamiReady\\TM\\ and StormReady/TsunamiReady\\TM\\ Application Forms AGENCY: National Oceanic... TsunamiReady and StormReady/TsunamiReady programs also in this information collection, is a...

  10. Monodisperse core-shell structured up-conversion Yb(OH)CO₃@YbPO₄:Er³+ hollow spheres as drug carriers.

    PubMed

    Xu, Zhenhe; Ma, Ping'an; Li, Chunxia; Hou, Zhiyao; Zhai, Xuefeng; Huang, Shanshan; Lin, Jun

    2011-06-01

    In this work, we report a facile solution-phase synthesis of monodisperse core-shell structured Yb(OH)CO₃@YbPO₄ hollow spheres (size around 380 nm) by utilizing the colloidal sphere of Yb(OH)CO₃ as the sacrificial template via the Kirkendall effect. The Er³+ doped Yb(OH)CO₃@YbPO₄ core-shell hollow spheres can be prepared similarly, which exhibit strong green emission under 980 nm NIR laser excitation even after loading with drug molecules. Most importantly, the sample can be used as an effective drug delivery carrier. The biocompatibility test on L929 fibroblast cells using MTT assay reveals low cytotoxicity of the system. A typical anticancer drug, doxorubicin hydrochloride (DOX), is used for drug loading, and the release properties, cytotoxicity, uptake behavior and therapeutic effects were examined. It is found that DOX is shuttled into cell by core-shell hollow spheres carrier and released inside cells after endocytosis, and the DOX-loaded spheres exhibited greater cytotoxicity than free DOX. These results indicate that the core-shell Er³+ doped Yb(OH)CO₃@YbPO₄ hollow spheres have potential for drug loading and delivery into cancer cells to induce cell death.

  11. Exchange interaction in the YbCrBr3-9 mixed dimer:  The origin of a strong Yb3+-Cr3+ exchange anisotropy

    NASA Astrophysics Data System (ADS)

    Mironov, V. S.; Chibotaru, L. F.; Ceulemans, A.

    2003-01-01

    The superexchange interaction between Yb3+ and Cr3+ ions in the mixed YbCrBr3-9 bioctahedral face-sharing dimer is quantitatively analyzed using a modified kinetic exchange theory, which is adapted to a realistic description of the electronic structure of lanthanide ions in solids. The general procedure of the calculation of the 4f-3d anisotropic exchange spin Hamiltonian is presented and applied to the YbCrBr3-9 dimer. The spin-Hamiltonian of the Yb3+-Cr3+ exchange interaction is found to be extremely anisotropic, H=JzSzYbSzCr+J⊥(SxYbSxCr+SyYbSyCr), with the antiferromagnetic Jz and ferromagnetic J⊥ parameters, where SμYb and SμCr (μ=x,y,z) are the components of the effective spin SYb=1/2 of the Yb3+ ion (corresponding to the ground Γ6 Kramers doublet) and the true spin SCr=3/2 of the Cr3+ ion, respectively. The calculated exchange parameters are quite consistent with the experimental data (Jz=-5.16 cm-1 and J⊥=+4.19 cm-1) at reasonable values of the Yb→Cr and Yb←Cr charge transfer energies. The contributions to the Jz and J⊥ exchange parameters from the individual states of the 4f12-3d4 and 4f14-3d2 charge transfer configurations are analyzed in detail and general regularities are established. Our results indicate that a very strong 4f-3d exchange anisotropy can appear even in the absence of the crystal-field anisotropy on the lanthanide ion.

  12. Intracellular distribution of TM4SF1 and internalization of TM4SF1-antibody complex in vascular endothelial cells

    SciTech Connect

    Sciuto, Tracey E.; Merley, Anne; Lin, Chi-Iou; Richardson, Douglas; Liu, Yu; Li, Dan; Dvorak, Ann M.; Dvorak, Harold F.; Jaminet, Shou-Ching S.

    2015-09-25

    Transmembrane-4 L-six family member-1 (TM4SF1) is a small plasma membrane-associated glycoprotein that is highly and selectively expressed on the plasma membranes of tumor cells, cultured endothelial cells, and, in vivo, on tumor-associated endothelium. Immunofluorescence microscopy also demonstrated TM4SF1 in cytoplasm and, tentatively, within nuclei. With monoclonal antibody 8G4, and the finer resolution afforded by immuno-nanogold transmission electron microscopy, we now demonstrate TM4SF1 in uncoated cytoplasmic vesicles, nuclear pores and nucleoplasm. Because of its prominent surface location on tumor cells and tumor-associated endothelium, TM4SF1 has potential as a dual therapeutic target using an antibody drug conjugate (ADC) approach. For ADC to be successful, antibodies reacting with cell surface antigens must be internalized for delivery of associated toxins to intracellular targets. We now report that 8G4 is efficiently taken up into cultured endothelial cells by uncoated vesicles in a dynamin-dependent, clathrin-independent manner. It is then transported along microtubules through the cytoplasm and passes through nuclear pores into the nucleus. These findings validate TM4SF1 as an attractive candidate for cancer therapy with antibody-bound toxins that have the capacity to react with either cytoplasmic or nuclear targets in tumor cells or tumor-associated vascular endothelium. - Highlights: • Anti-TM4SF1 antibody 8G4 was efficiently taken up by cultured endothelial cells. • TM4SF1–8G4 internalization is dynamin-dependent but clathrin-independent. • TM4SF1–8G4 complexes internalize along microtubules to reach the perinuclear region. • Internalized TM4SF1–8G4 complexes pass through nuclear pores into the nucleus. • TM4SF1 is an attractive candidate for ADC cancer therapy.

  13. Tuning Mixed-Valent Eu(2+) /Eu(3+) in Strontium Formate Frameworks for Multichannel Photoluminescence.

    PubMed

    Liu, Wei; Liu, Lijia; Wang, Yanlong; Chen, Lanhua; McLeod, John A; Yang, Linju; Zhao, Jia; Liu, Zhiyong; Diwu, Juan; Chai, Zhifang; Albrecht-Schmitt, Thomas E; Liu, Guokui; Wang, Shuao

    2016-08-01

    Cooperative performance of mixed-valent Eu(2+) /Eu(3+) in single-compound phosphors offers significant advantages in color rendering and luminescence efficiency, but their synthesis is challenging because of Eu(2+) oxidation. Using the tunable nature of the metal-ion nodes in metal-organic frameworks (MOFs), we present an in situ reduction and crystallization route for preparing MOFs and doping Eu(2+) /Eu(3+) with a controlled ratio. These materials exhibit rich photoluminescence, including intrinsic- and sensitized-emissions of Eu(2+) and Eu(3+) , and long-lived luminescence from charge transfer. Color rendering can be easily achieved by fine-tuning the valence states of Eu. A linear relation between temperature and the intensity ratio of Eu(2+) /Eu(3+) emissions provides outstanding properties for applications as self-calibrated luminescent thermometers with a wide working temperature range. Further incorporation of Tb(3+) into the MOFs results in white light, utilizing all Eu(2+) ,Tb(3+) , and Eu(3+) emissions in a single crystalline lattice. PMID:27305606

  14. Fabrication and photoluminescence properties of Cr:YAG and Yb,Cr:YAG transparent ceramic

    NASA Astrophysics Data System (ADS)

    Chen, Xingtao; Lu, Tiecheng; Wei, Nian; Lu, Zhongwen; Chen, Lijia; Zhang, Qinghua; Cheng, Gang; Qi, Jianqi

    2015-11-01

    Cr:YAG and Yb/Cr:YAG transparent ceramics containing Ca as charge counter element were fabricated by vacuum sintering technique using the co-precipitation synthesis of raw powders. Their spectral and luminescence properties as well as the influence of Cr3+ concentration on the optical properties of Yb,Cr:YAG ceramic were investigated. Results show the transmittance of 10 at.% Yb, 0.25 at.% Cr:YAG and 0.25 at.% Cr:YAG reaches 83% at 1200 nm and 81% at 1400 nm, respectively. And the Yb,Cr:YAG ceramics exhibit a pore free structure with an average grain size of about 5 μm. After annealing, most of Cr3+ ions transform into Cr4+. In the case of excitation wavelength of 440 nm, a sharp emission peak of 694 nm appeared in the Yb,Cr:YAG ceramic before annealing and the band enhanced with the increase of the Cr3+ concentration, which is attributed to the 4T2g-4A2g fluorescence transition. The emission spectrums and fluorescence decays manifest that both the luminescent intensity and the lifetimes of Yb,Cr:YAG are lower than Yb:YAG ceramic and the lifetimes of Yb,Cr:YAG and Yb:YAG are 0.93 and 2.38 ms, respectively. This results demonstrate the existence of the ground state absorption of Cr4+ in the Yb,Cr:YAG ceramic. Experimental evidence proved that Yb,Cr:YAG transparent ceramics could be a potential material for passive self-Q-switched solid-state laser.

  15. Unified formalism for TE and TM beam propagators

    NASA Astrophysics Data System (ADS)

    Poladian, Leon; Ladouceur, Francois J.

    1998-07-01

    The unification of transverse electric (TE) and transverse magnetic (TM) beam propagation algorithms is made possible through a transformation which converts the wave equation for TM fields in planar waveguides into a form identical to the corresponding TE wave equation. The transformation can be applied to any smoothly varying waveguide. This transformation can be made independently of any paraxial or other approximations. Thus, any TE propagation algorithm can also be applied immediately to TM fields without additional approximations. This includes the classical fast Fourier transform beam propagator, which has not previously been applied successfully to TM propagation. We also specifically develop a Finite Difference Beam Propagation Method that applies to both TE and TM propagation in 1D (planar) geometry. Previous implementations for the TM case involve an approximation that in certain circumstances leads to severe errors (including the totally unphysical occurrence of field amplification). This is the first TM propagator which exactly conserves power. We also investigate the role of the reference background wavenumber (or index) and clarify its role as it is dynamically adapted. The algorithms proposed are easily adaptable to wide-angle beam propagators and to modern transparent boundary conditions. The extension of these ideas to rapidly varying structures (such as Bragg gratings) is also briefly discussed.

  16. TE, TM modes photorefractive surface waves and their coupling

    NASA Astrophysics Data System (ADS)

    Zhang, T. H.; Shao, W. W.; Li, K.; Liu, X. S.; Xu, J. J.

    2008-03-01

    The nonlinear equations of photorefractive surface waves (PR SWs) with diffusion mechanism are established and calculated numerically for both TE mode and TM mode and their coupling for the first time. The characteristics of TE mode and TM mode are analyzed, such as propagation constants, spatial distribution, penetration depths etc. For relative larger propagation constant, most of the surface wave energy is concentrated on the Ax component of TM mode, and the penetration depth of Ay of TE mode is always larger than that of Ax of TM mode because electro-optical coefficient r13 is always smaller than r33 in general PRC. As a result, the energy of the PR SW is better confined near the surface for TM mode than that for TE mode. When both TE and TM modes PR SWs are present, they will be coupled drastically and the Ax component of TM mode and Ay component of TE mode resonate in the volume of PR medium. As a result, the PR SWs cannot remain decay, and the light energy can not be confined near the surface steadily and the modes are destroyed. The results provide the theoretical instructions and are very significant to generate steady and high density PR SW in practice.

  17. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    SciTech Connect

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.

  18. Ends of the line for tmRNA-SmpB

    SciTech Connect

    Hudson, Corey M.; Lau, Britney Y.; Williams, Kelly P.

    2014-08-13

    Genes for the RNA tmRNA and protein SmpB, partners in the trans-translation process that rescues stalled ribosomes, have previously been found in all bacteria and some organelles. We validate recent identification of tmRNA homologs in oomycete mitochondria by finding partner genes from oomycete nuclei that target SmpB to the mitochondrion. Exhaustive search now identifies a small number of complete, often highly derived, bacterial genomes that appear to lack a functional copy of one or the other partner gene (but not both). Three groups with reduced genomes have lost the central loop of SmpB, which is thought to improve alanylation and EF-Tu activation: Carsonella, Hodgkinia and the hemplasmas (hemotropic Mycoplasma). Carsonella has also lost the SmpB C-terminal tail, thought to stimulate the decoding center of the ribosome. Carsonella moreover exhibits gene overlap such that tmRNA maturation should produce a non-stop smpB mRNA, and one isolate exhibits complete degradation of the tmRNA gene yet its smpB shows no evidence for relaxed selective constraint. After loss of the SmpB central loop in the hemoplasmas, a subclade apparently lost tmRNA. At least some of the tmRNA/SmpB-deficient strains appear to further lack the ArfA and ArfB backup systems for ribosome rescue. The most frequent neighbors of smpB are the tmRNA gene, a ratA/rnfH unit, and the gene for RNaseR, a known physical and functional partner of tmRNA-SmpB. The tmRNA Website has moved and been updated, adding an SmpB sequence database (http://bioinformatics.sandia.gov/tmrna).

  19. Ends of the line for tmRNA-SmpB

    DOE PAGES

    Hudson, Corey M.; Lau, Britney Y.; Williams, Kelly P.

    2014-08-13

    Genes for the RNA tmRNA and protein SmpB, partners in the trans-translation process that rescues stalled ribosomes, have previously been found in all bacteria and some organelles. We validate recent identification of tmRNA homologs in oomycete mitochondria by finding partner genes from oomycete nuclei that target SmpB to the mitochondrion. Exhaustive search now identifies a small number of complete, often highly derived, bacterial genomes that appear to lack a functional copy of one or the other partner gene (but not both). Three groups with reduced genomes have lost the central loop of SmpB, which is thought to improve alanylation andmore » EF-Tu activation: Carsonella, Hodgkinia and the hemplasmas (hemotropic Mycoplasma). Carsonella has also lost the SmpB C-terminal tail, thought to stimulate the decoding center of the ribosome. Carsonella moreover exhibits gene overlap such that tmRNA maturation should produce a non-stop smpB mRNA, and one isolate exhibits complete degradation of the tmRNA gene yet its smpB shows no evidence for relaxed selective constraint. After loss of the SmpB central loop in the hemoplasmas, a subclade apparently lost tmRNA. At least some of the tmRNA/SmpB-deficient strains appear to further lack the ArfA and ArfB backup systems for ribosome rescue. The most frequent neighbors of smpB are the tmRNA gene, a ratA/rnfH unit, and the gene for RNaseR, a known physical and functional partner of tmRNA-SmpB. The tmRNA Website has moved and been updated, adding an SmpB sequence database (http://bioinformatics.sandia.gov/tmrna).« less

  20. Review of Tm and Ho Materials; Spectroscopy and Lasers

    NASA Technical Reports Server (NTRS)

    Walsh, Brian M.

    2008-01-01

    A review of Tm and Ho materials is presented, covering some fundamental aspects on the spectroscopy and laser dynamics in both single and co-doped systems. Following an introduction to 2- m lasers, applications and historical development, the physics of quasi-four level lasers, energy transfer and modeling are discussed in some detail. Recent developments in using Tm lasers to pump Ho lasers are discussed, and seen to offer some advantages over conventional Tm:Ho lasers. This article is not intended as a complete review, but as a primer for introducing concepts and a resource for further study.

  1. Relative Radiometric Calibration of LANDSAT TM Reflective Bands

    NASA Technical Reports Server (NTRS)

    Barker, J. L.

    1985-01-01

    Results and recommendations pertaining to the characterization of the relative radiometric calibration of the protoflight thematic mapper (TM/PF) on the LANDSAT-4 satellite are presented. Some preliminary pre-launch and in-orbit results are also included from the flight model (TM/F) on LANDSAT-5. A common scientific methodology and terminology is outlined for characterizing the radiometry of both TM sensors. The magnitude of the most significant sources of radiometric variability are discussed and methods are recommended for achieving the exceptional potential inherent in the radiometric precision and accuracy of the sensors.

  2. Quasi four-level Tm:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Hutcheson, Ralph L. (Inventor); Rodriguez, Waldo J. (Inventor)

    1997-01-01

    A quasi four-level solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG-based host material doped to a final concentration between about 2% and about 7% thulium (Tm) ions. For the more heavily doped final concentrations, the LuAG-based host material is a LuAG seed crystal doped with a small concentration of Tm ions. Laser diode arrays are disposed transversely to the laser crystal for energizing the Tm ions.

  3. Stimulated Raman adiabatic passage in Tm{sup 3+}:YAG

    SciTech Connect

    Alexander, A. L.; Lauro, R.; Louchet, A.; Chaneliere, T.; Le Goueet, J. L.

    2008-10-01

    We report on the experimental demonstration of stimulated Raman adiabatic passage in a Tm{sup 3+}:YAG crystal. Tm{sup 3+}:YAG is a promising material for use in quantum information processing applications, but as yet there are few experimental investigations of coherent Raman processes in this material. We investigate the effect of inhomogeneous broadening and Rabi frequency on the transfer efficiency and the width of the two-photon spectrum. Simulations of the complete Tm{sup 3+}:YAG system are presented along with the corresponding experimental results.

  4. Tm:germanate Fiber Laser: Tuning And Q-switching

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Walsh, Brian M.; Reichle, Donald J.; DeYoung, R. J.; Jiang, Shibin

    2007-01-01

    A Tm:germanate fiber laser produced >0.25 mJ/pulse in a 45 ns pulse. It is capable of producing multiple Q-switched pulses from a single p ump pulse. With the addition of a diffraction grating, Tm:germanate f iber lasers produced a wide, but length dependent, tuning range. By s electing the fiber length, the tuning range extends from 1.88 to 2.04 ?m. These traits make Tm:germanate lasers suitable for remote sensin g of water vapor.

  5. Preparation, Biological Evaluation and Dosimetry Studies of 175Yb-Bis-Phosphonates for Palliative Treatment of Bone Pain

    PubMed Central

    Fakhari, Ashraf; Jalilian, Amir R.; Yousefnia, Hassan; Shanehsazzadeh, Saeed; Samani, Ali Bahrami; Daha, Fariba Johari; Ardestani, Mehdi Shafiee; Khalaj, Ali

    2015-01-01

    Objective: Optimized production and quality control of ytterbium-175 (Yb-175) labeled pamidronate and alendronate complexes as efficient agents for bone pain palliation has been presented. Methods: Yb-175 labeled pamidronate and alendronate (175Yb-PMD and 175Yb-ALN) complexes were prepared successfully at optimized conditions with acceptable radiochemical purity, stability and significant hydroxyapatite absorption. The biodistribution of complexes were evaluated up to 48 h, which demonstrated significant bone uptake ratios for 175Yb-PAM at all-time intervals. It was also detected that 175Yb-PAM mostly washed out and excreted through the kidneys. Results: The performance of 175Yb-PAM in an animal model was better or comparable to other 175Yb-bone seeking complexes previously reported. Conclusion: Based on calculations, the total body dose for 175Yb-ALN is 40% higher as compared to 175Yb-PAM (especially kidneys) indicating that 175Yb-PAM is probably a safer agent than 175Yb-ALN. PMID:27529886

  6. ASTROCULTURE (TM) root metabolism and cytochemical analysis

    NASA Technical Reports Server (NTRS)

    Porterfield, D. M.; Barta, D. J.; Ming, D. W.; Morrow, R. C.; Musgrave, M. E.

    2000-01-01

    Physiology of the root system is dependent upon oxygen availability and tissue respiration. During hypoxia nutrient and water acquisition may be inhibited, thus affecting the overall biochemical and physiological status of the plant. For the Astroculture (TM) plant growth hardware, the availability of oxygen in the root zone was measured by examining the changes in alcohol dehydrogenase (ADH) activity within the root tissue. ADH activity is a sensitive biochemical indicator of hypoxic conditions in plants and was measured in both spaceflight and control roots. In addition to the biochemical enzyme assays, localization of ADH in the root tissue was examined cytochemically. The results of these analyses showed that ADH activity increased significantly as a result of spaceflight exposure. Enzyme activity increased 248% to 304% in dwarf wheat when compared with the ground controls and Brassica showed increases between 334% and 579% when compared with day zero controls. Cytochemical staining revealed no differences in ADH tissue localization in any of the dwarf wheat treatments. These results show the importance of considering root system oxygenation in designing and building nutrient delivery hardware for spaceflight plant cultivation and confirm previous reports of an ADH response associated with spaceflight exposure.

  7. YB-1 Synthesis Is Regulated by mTOR Signaling Pathway

    PubMed Central

    Lyabin, Dmitry N.; Eliseeva, Irina A.; Ovchinnikov, Lev P.

    2012-01-01

    YB-1 is a eukaryotic protein with numerous intra- and extracellular functions based on its ability to interact with RNA, DNA, and many proteins. In spite of achievements in studying its functions, regulation of YB-1 synthesis in the cell remains poorly understood. In the current study Western and Northern blotting were used to determine the amounts of YB-1 and YB-1 mRNA in rabbit organs and several cell lines. As found, in the majority of studied eukaryotic cells a considerable proportion of YB-1 mRNA was stored in free mRNPs, i.e., was poorly translated. Also, we demonstrated that YB-1 synthesis depended on conditions that determined the rate of cell division. Specific suppression of YB-1 synthesis resulted from inhibition of the mTOR signaling pathway with inhibitor PP242, but not rapamycin. Experiments on reporter constructs showed that dependence of YB-1 mRNA translation on activity of the mTOR signaling pathway was dictated by 5′ untranslated regions of this mRNA, irrelatively of the TOP-like sequences at the beginning of 5′ UTR. PMID:23285076

  8. Cold shock protein YB-1 is involved in hypoxia-dependent gene transcription.

    PubMed

    Rauen, Thomas; Frye, Bjoern C; Wang, Jialin; Raffetseder, Ute; Alidousty, Christina; En-Nia, Abdelaziz; Floege, Jürgen; Mertens, Peter R

    2016-09-16

    Hypoxia-dependent gene regulation is largely orchestrated by hypoxia-inducible factors (HIFs), which associate with defined nucleotide sequences of hypoxia-responsive elements (HREs). Comparison of the regulatory HRE within the 3' enhancer of the human erythropoietin (EPO) gene with known binding motifs for cold shock protein Y-box (YB) protein-1 yielded strong similarities within the Y-box element and 3' adjacent sequences. DNA binding assays confirmed YB-1 binding to both, single- and double-stranded HRE templates. Under hypoxia, we observed nuclear shuttling of YB-1 and co-immunoprecipitation assays demonstrated that YB-1 and HIF-1α physically interact with each other. Cellular YB-1 depletion using siRNA significantly induced hypoxia-dependent EPO production at both, promoter and mRNA level. Vice versa, overexpressed YB-1 significantly reduced EPO-HRE-dependent gene transcription, whereas this effect was minor under normoxia. HIF-1α overexpression induced hypoxia-dependent gene transcription through the same element and accordingly, co-expression with YB-1 reduced HIF-1α-mediated EPO induction under hypoxic conditions. Taken together, we identified YB-1 as a novel binding factor for HREs that participates in fine-tuning of the hypoxia transcriptome. PMID:27524241

  9. Photoelectron spectra of thulium atoms encapsulated C82 fullerene, Tm2@C82 (III) and Tm2C2@C82 (III)

    NASA Astrophysics Data System (ADS)

    Miyazaki, Takafumi; Tokumoto, Youji; Sumii, Ryohei; Yagi, Hajime; Izumi, Noriko; Shinohara, Hisanori; Hino, Shojun

    2014-03-01

    Ultraviolet photoelectron spectra (UPS) and X-ray photoelectron spectra (XPS) of two thulium atoms and thulium-carbide cluster entrapped fullerenes, Tm2@C82 (III) and Tm2C2@C82 (III), were measured using synchrotron radiation and MgKα X-ray light sources. The UPS spectral onset energy of these endohedral fullerenes is around 0.9 eV, which is smaller than that of 1.2 eV of empty C82. The UPS of Tm2@C82 (III) and Tm2C2@C82 (III) resemble each other. Further, the UPS of Tm2@C82 (III), Y2@C82-C3v and Er2@C82-C3v are almost identical and as well as are Tm2C2@C82 (III), Y2C2@C82-C3v and Er2C2@C82-C3v. The XPS Tm4d5/2 peaks of Tm2@C82 and Tm2C2@C82 appear at higher binding energy region than that of Tm@C82, which suggests the oxidation states of Tm atoms in Tm2@C82 (III) and Tm2C2@C82 are higher than that in Tm@C82.

  10. Distribution of 152Eu and 154Eu in the 'alluvial soil-rhizosphere-plant roots' system.

    PubMed

    Kropatcheva, Marya; Chuguevsky, Alexei; Melgunov, Mikhail

    2012-04-01

    Accumulation of (152)Eu and (15)(4)Eu isotopes in bulk soil and rhizosphere soil in the near-field zone of influence of the Krasnoyarsk Mining and Chemical Combine was studied. An uneven distribution of specific activity of Eu isotopes was observed, with the gross specific activities of the isotopes in the bulk soil exceeding those of the rhizosphere. In the most contaminated locations the fine and the coarse granulometric fractions are enriched with the isotopes. A laboratory experiment indicated potential removal of soluble Eu isotopes by river flood waters may amount to 3% of the total Eu in both bulk and rhizosphere soils. The root system of plants growing in the contaminated territory accumulates (152)Eu and (154)Eu, although the isotopes were not discovered in aboveground parts of plants. Root-hairs were found to be the most contaminated.

  11. Lattice vibration and absorbance of Er:Yb:YCOB single crystals

    NASA Astrophysics Data System (ADS)

    Lu, Gui-Wu; Li, Chun-Xi; Wang, Wen-Chuan; Wang, Zi-Hao; Xia, Hai-Rui; Zhang, Huai-Jin; Meng, Xian-Lin; Li, Li-Xia

    2003-01-01

    Er 3+- and Yb 3+-doped yttrium calcium oxoborate Er:Yb:YCa 4O(BO 3) 3 (Er:Yb:YCOB) crystallizes with a fluorapatite-type structure in the monoclinic system. Its lattice vibrational modes were calculated by using space group theory, and Raman spectra were measured at room temperature with different scattering geometry projects. The experiments show that the characteristic lattice vibrational modes of Er:Yb:YCOB crystal arise mainly from the internal vibrations of the BO3, CaO6, and YO 6 groups. The three-dimensional network structure of Er:Yb:YCOB crystal is identified, and its excellent nonlinear optical (NLO) properties are mainly attributed to the BO 3 clusters that connects all the distorted YO 6 and CaO 6 octahedral clusters together. The combination of the strong absorption at 976 nm and the strong emission at 1537 nm makes this material very promising for use in an infrared laser system.

  12. Fabrication and characterization of highly transparent Yb3+: Y2O3 ceramics

    NASA Astrophysics Data System (ADS)

    Ning, Kaijie; Wang, Jun; Luo, Dewei; Ma, Jie; Zhang, Jian; Dong, Zhi Li; Kong, Ling Bing; Tang, Ding Yuan

    2015-12-01

    Highly transparent Yb3+ doped Y2O3 (Yb3+: Y2O3) ceramics was fabricated by a solid-state reaction method using ZrO2 and La2O3 as additives. The morphology of the prepared powder was investigated and the phase of the sintered Yb3+: Y2O3 ceramics sample was identified. The microstructure, transmittance spectrum, Vickers hardness and fracture toughness for the as-sintered Yb3+: Y2O3 ceramics were measured. The average grain size was about 9.11 μm and the transmittance at the wavelength of 2000 nm was about 82.0%, which was 99% of the theoretical value. ZrO2 and La2O3 were useful additives for highly transparent Yb3+: Y2O3 ceramics fabrication and mechanical properties improvement.

  13. A novel type of splayed ferromagnetic order observed in Yb2Ti2O7.

    PubMed

    Yaouanc, A; Dalmas de Réotier, P; Keller, L; Roessli, B; Forget, A

    2016-10-26

    The pyrochlore insulator Yb2Ti2O7 has attracted the attention of experimentalists and theoreticians alike for about 15 years. Conflicting neutron diffraction data on the possible existence of magnetic Bragg reflections at low temperature have been published. Here we report the observation of magnetic Bragg reflections by neutron powder diffraction at 60 mK. The magnetic diffraction pattern is analyzed using representation theory. We find Yb2Ti2O7 to be a splayed ferromagnet as reported for Yb2Sn2O7, a sibling compound with also dominating ferromagnetic interactions as inferred from the positive Curie-Weiss temperature. However, the configuration of the magnetic moment components perpendicular to the easy axis is of the all-in-all-out type in Yb2Ti2O7 while it is two-in-two-out in the Yb2Sn2O7. An overall experimental picture of the magnetic properties emerges. PMID:27557664

  14. Enhancement of Tb-Yb quantum cutting emission by inverse opal photonic crystals

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Qiu, Jianbei; Song, Zhiguo; Yang, Zhengwen; Yin, Zhaoyi; Zhou, Dacheng; Wang, Siqin

    2016-04-01

    Yb3+, Tb3+ co-doped YPO4 inverse opal photonic crystal was prepared directly by sol-gel technique in combination with self-assembly method. With the influence of the photonic band gap, quantum cutting emission of Tb3+, Yb3+ was investigated in photonic crystals by photoluminescence and fluorescence lifetime. The result clearly shows that, when the spontaneous emission of donor Tb3+ is inhibited by photonic band gap, Tb3+-Yb3+ quantum cutting quantum efficiency from Tb3+ to Yb3+ could be enhanced from 131.2% to 140.5%. The mechanisms for the influence of the photonic band gap on quantum cutting process of Tb3+ and Yb3+ are discussed. We believe that the present work will be valuable for the foundational study of quantum cutting energy transfer process and application of quantum cutting optical devices in spectral modification materials for silicon solar cells.

  15. A novel type of splayed ferromagnetic order observed in Yb2Ti2O7

    NASA Astrophysics Data System (ADS)

    Yaouanc, A.; Dalmas de Réotier, P.; Keller, L.; Roessli, B.; Forget, A.

    2016-10-01

    The pyrochlore insulator Yb2Ti2O7 has attracted the attention of experimentalists and theoreticians alike for about 15 years. Conflicting neutron diffraction data on the possible existence of magnetic Bragg reflections at low temperature have been published. Here we report the observation of magnetic Bragg reflections by neutron powder diffraction at 60 mK. The magnetic diffraction pattern is analyzed using representation theory. We find Yb2Ti2O7 to be a splayed ferromagnet as reported for Yb2Sn2O7, a sibling compound with also dominating ferromagnetic interactions as inferred from the positive Curie-Weiss temperature. However, the configuration of the magnetic moment components perpendicular to the easy axis is of the all-in-all-out type in Yb2Ti2O7 while it is two-in-two-out in the Yb2Sn2O7. An overall experimental picture of the magnetic properties emerges.

  16. Noncoding RNAs that associate with YB-1 alter proliferation in prostate cancer cells

    PubMed Central

    Liu, Teresa T.; Arango-Argoty, Gustavo; Li, Zhihua; Lin, Yuefeng; Kim, Sang Woo; Dueck, Anne; Ozsolak, Fatih; Monaghan, A. Paula; Meister, Gunter; DeFranco, Donald B.; John, Bino

    2015-01-01

    The highly conserved, multifunctional YB-1 is a powerful breast cancer prognostic indicator. We report on a pervasive role for YB-1 in which it associates with thousands of nonpolyadenylated short RNAs (shyRNAs) that are further processed into small RNAs (smyRNAs). Many of these RNAs have previously been identified as functional noncoding RNAs (http://www.johnlab.org/YB1). We identified a novel, abundant, 3′-modified short RNA antisense to Dicer1 (Shad1) that colocalizes with YB-1 to P-bodies and stress granules. The expression of Shad1 was shown to correlate with that of YB-1 and whose inhibition leads to an increase in cell proliferation. Additionally, Shad1 influences the expression of additional prognostic markers of cancer progression such as DLX2 and IGFBP2. We propose that the examination of these noncoding RNAs could lead to better understanding of prostate cancer progression. PMID:25904138

  17. Noncoding RNAs that associate with YB-1 alter proliferation in prostate cancer cells.

    PubMed

    Liu, Teresa T; Arango-Argoty, Gustavo; Li, Zhihua; Lin, Yuefeng; Kim, Sang Woo; Dueck, Anne; Ozsolak, Fatih; Monaghan, A Paula; Meister, Gunter; DeFranco, Donald B; John, Bino

    2015-06-01

    The highly conserved, multifunctional YB-1 is a powerful breast cancer prognostic indicator. We report on a pervasive role for YB-1 in which it associates with thousands of nonpolyadenylated short RNAs (shyRNAs) that are further processed into small RNAs (smyRNAs). Many of these RNAs have previously been identified as functional noncoding RNAs (http://www.johnlab.org/YB1). We identified a novel, abundant, 3'-modified short RNA antisense to Dicer1 (Shad1) that colocalizes with YB-1 to P-bodies and stress granules. The expression of Shad1 was shown to correlate with that of YB-1 and whose inhibition leads to an increase in cell proliferation. Additionally, Shad1 influences the expression of additional prognostic markers of cancer progression such as DLX2 and IGFBP2. We propose that the examination of these noncoding RNAs could lead to better understanding of prostate cancer progression. PMID:25904138

  18. Spectroscopic and thermal characterizations of Yb:LaF3 single crystal

    NASA Astrophysics Data System (ADS)

    Hong, Jiaqi; Zhang, Lianhan; Hang, Yin; Xu, Min

    2016-10-01

    A Yb3+ doped LaF3 laser crystal was detailed investigated by both spectroscopic and thermal measurements. A peak absorption at 974 nm with FWHM broader than 60 nm makes the crystal suitable to InGaAs LDs. Fluorescence spectrum and calculated spectroscopic parameters show potential of Yb:LaF3 crystal to laser operations around 1009 nm. A relatively long fluorescence lifetime of 2.92 ms was detected for Yb3+:2F5/2 manifold. The thermal diffusivity and specific heat capacity in the range of 300-575 K were studied to calculate the thermal conductivity of Yb:LaF3. The results indicate that the Yb:LaF3 crystal is a good candidate for diode-pumped ∼1 μm solid-state laser applications.

  19. {beta}-decay study of {sup 150}Er, {sup 152}Yb, and {sup 156}Yb: Candidates for a monoenergetic neutrino beam facility

    SciTech Connect

    Estevez Aguado, M. E.; Algora, A.; Rubio, B.; Bernabeu, J.; Nacher, E.; Tain, J. L.; Gadea, A.; Agramunt, J.; Burkard, K.; Hueller, W.; Doering, J.; Kirchner, R.; Mukha, I.; Plettner, C.; Roeckl, E.; Grawe, H.; Collatz, R.; Hellstroem, M.; Cano-Ott, D.; Karny, M.

    2011-09-15

    The {beta} decays of {sup 150}Er, {sup 152}Yb, and {sup 156}Yb nuclei are investigated using the total absorption spectroscopy technique. These nuclei can be considered possible candidates for forming the beam of a monoenergetic neutrino beam facility based on the electron capture (EC) decay of radioactive nuclei. Our measurements confirm that for the cases studied the EC decay proceeds mainly to a single state in the daughter nucleus.

  20. High-spin states in odd-odd 168Tm

    SciTech Connect

    Cardona, M. A.; Hojman, D.; Davidson, J.; Davidson, M.; Kreiner, A. J.; Bazzacco, D.; Lenzi, S. M.; Rossi Alvarez, C.; Blasi, N.; Debray, M. E.; Levinton, G.; Marti, G.; De Poli, M.; Napoli, D. R.; Lo Bianco, G.

    2007-02-12

    High-spin states in 168Tm were investigated by means of {gamma}-ray spectroscopy techniques using the GASP multidetector array. Rotational bands have been established and identified in terms of their configurations.

  1. Observation of the second proton alignment in {sup 160}Tm

    SciTech Connect

    Lagergren, K.; Riley, M.A.; Campbell, D.B.; Simpson, J.; Appelbe, D.E.; Joss, D.T.; Bednarczyk, P.; Chandler, C.; Choy, P.T.W.; Paul, E.S.; Curien, D.

    2005-11-01

    High-spin states in the doubly odd nucleus {sup 160}Tm have been investigated using the {sup 130}Te({sup 35}Cl,5n) reaction and the Euroball {gamma}-ray detector array. The previously established rotational structures in {sup 160}Tm were extended, leading to the first observation of the second (h{sub 11/2}){sup 2} proton band crossing in this nucleus. This crossing is found to occur at a higher rotational frequency in {sup 160}Tm than in lighter Tm isotopes. This trend resembles that of the first (h{sub 11/2}){sup 2} proton band crossing found in neighboring Er nuclei and is associated with a predicted increase in deformation as a function of neutron number in these isotopes.

  2. DigitalGlobe(TM) Incorporated Corporate and System Update

    NASA Technical Reports Server (NTRS)

    Thomassie, Brett

    2007-01-01

    This viewgraph presentation describes a system update of Quickbird, the world's highest resolution commercial imaging satellite, operated by DigitalGlobe (TM) Incorporated. A satellite comparison of Quickbird, WorldView-60, and WorldView-110 is also presented.

  3. Characterization of vapour-transport-equilibrated Yb(/Er):LiNbO3 crystals

    NASA Astrophysics Data System (ADS)

    Zhang, De-Long; Wong, W. H.; Pun, E. Y. B.

    2004-11-01

    Visible and infrared absorption, Raman scattering, x-ray powder diffraction and scanning electron microscope (SEM) have been used to characterize Er/Yb (0.6 mol%/0.3 mol%) codoped and singly Yb-doped (1.2 mol%) Z-cut LiNbO3 crystals that were vapour-transport-equilibrated (VTE) at 1110 and 1120 °C for 100, 120 and 220 h in a Li-rich atmosphere. Optical absorption edge and 153 cm-1 E(TO) phonon linewidth have been used to roughly evaluate the composition of the crystals. The results obtained show that the VTE treatment has brought all crystals towards stoichiometric composition. As a relatively strong VTE condition was adopted, the treatment results in the formation of submicron-sized ErNbO4 (+YbNbO4) and YbNbO4 flat polyhedron-like precipitates in the Er/Yb:LiNbO3 and Yb:LiNbO3 crystals, respectively. On the other hand, a relatively weak VTE procedure cannot induce the precipitation of both the singly and doubly doped crystals. The characteristic optical absorptions, characteristic x-ray diffractions, crystalline structure and crystallographic morphology of the ErNbO4 and YbNbO4 precipitates are discussed, summarized and compared with those of singly Er-doped LiNbO3 crystals reported previously. The absorption characteristics of the unprecipitated Er/Yb codoped and singly Yb-doped crystals are also summarized and compared with the case of singly Er doping. An atomic force microscope has been used to further verify the SEM results and to evaluate the roughness of the surface of precipitated crystals. Optical absorption measurement was also carried out on a precipitated Er/Yb codoped crystal with polished surfaces to verify that the precipitates grow not only on the surface of the crystal but also in the bulk.

  4. Synthesis, crystal structure and physical properties of Yb11Bi10 -xSnx

    NASA Astrophysics Data System (ADS)

    Liang, Ying; Cardoso-Gil, Raul; Schnelle, Walter; Zhao, Jing-Tai; Grin, Yuri

    2013-04-01

    The intermetallic phase Yb11Bi10 -xSnx (x = 0 and 4.8) crystallizing in the Ho11Ge10 structure type was synthesized and characterized. The crystal structure was established by single-crystal X-ray diffraction data in the tetragonal space group I4/mmm (no.139), Pearson code tI84, Z = 4, a = 12.2043(4) Å, c = 17.7227(9) Å, and V = 2639.7(2) Å3, Rgt(F) = 0.040, 763 observed reflections for Yb11Bi10, and a = 12.0183(5) Å, c = 17.413(1) Å, and V = 2515.1(2) Å3, Rgt(F) = 0.027, 762 observed reflections for Yb11Bi5.2Sn4.8. The crystal structure of Yb11Bi10 contains three discrete anionic moieties: isolated Bi3- anions, Bi24- dimers and Bi44- squares. In Yb11Bi5.2Sn4.8, the square units are formed solely by Sn, and the structure shows a mixed Bi/Sn occupancy at the 8i and 16m Wyckoff sites. Magnetization measurements show that the title phase contains ytterbium exclusively in the 4f14 configuration up to 400 K. The Yb-LIII X-ray absorption spectrum attests also the presence of Yb with a 4f14 (Yb2+) configuration for Yb11Bi10, while the average valence of ytterbium was found to be 2.09 for Yb11Bi5.2Sn4.8.

  5. K = 6+ Isomers in Hf, yb and W Nuclei

    NASA Astrophysics Data System (ADS)

    Rath, Aswini Kumar; Walker, P. M.; Praharaj, C. R.; Xu, F. R.

    Using deformed Hartree-Fock and angular momentum projection (PHF) technique we try to understand the intrinsic structure and the systematics in the life times of K = 6+ isomers in the Hf isotopes (in 172-178Hf nuclei) and N = 104 Yb, Hf and W isotones. The band structure in 172Hf is reasonably well reproduced. The variation in the B(E2;2+ → 0+) values in the Hf isotopes as well as N = 104 isotones are well reproduced. The calculated K-forbidden E2 transition probabilities from the isomer bandheads to the 4+ yrast states qualitatively explain the variation of the lifetimes with N and Z.

  6. Resonant photoemission of oxidized Yb: Experiment and theory

    NASA Astrophysics Data System (ADS)

    Schmidt-May, J.; Gerken, F.; Nyholm, R.; Davis, L. C.

    1984-11-01

    The oxidation-induced valence change of Yb leads to a single 4f hole in the ground state. The creation of the 4f13 configuration which does not exist for any pure rare-earth metal makes it possible to analyze the 4d-->4f Fano resonance for a simple system experimentally as well as theoretically. Calculated Fano profiles for the 4f12 final-state multiplets are in good agreement with photoemission measurements taken with the FLIPPER monochromator at Hamburger Synchrotron-strahlungslabor, Deutsches Elektronen-Synchrotron, using synchrotron radiation from the storage ring DORIS.

  7. Chicken Y-box proteins chk-YB-1b and chk-YB-2 repress translation by sequence-specific interaction with single-stranded RNA.

    PubMed Central

    Swamynathan, S K; Nambiar, A; Guntaka, R V

    2000-01-01

    Y-Box proteins comprise a large family of multifunctional proteins with a wide spectrum of activities in both transcription and translational regulation of gene expression. Earlier, we have reported on the involvement of chk-YB-2 in transcriptional regulation of Rous sarcoma virus long terminal repeats and the involvement of chk-YB-1b in transcriptional regulation of alpha1(I) collagen genes. Here, we have investigated the potential role of chk-YB-2 and chk-YB-1b in RNA metabolism. We report that chk-YB-2 and chk-YB-1b are localized predominantly in the cytoplasm and that they both can bind single-stranded RNA in a sequence-specific and reversible manner. Well-conserved cold-shock domain, N-terminal proline-rich domain and the alternating clusters of acidic and basic amino acids located in the C-terminal ends of these two proteins were all found to be necessary for their RNA-binding ability. Further, we demonstrate that these two proteins inhibit translation in vitro and that binding to RNA is required for this inhibition. The significance of these results is discussed. PMID:10816422

  8. In-Situ Growth of Yb2O3 Layer for Sublimation Suppression for Yb14MnSb11 Thermoelectric Material for Space Power Applications

    NASA Technical Reports Server (NTRS)

    Nesbitt, James A.; Opila, Elizabeth J.; Nathal, Michael V.

    2012-01-01

    The compound Yb14MnSb11 is a p-type thermoelectric material of interest to the National Aeronautics and Space Administration (NASA) as a candidate replacement for the state-of-the-art Si-Ge used in current radioisotope thermoelectric generators (RTGs). Ideally, the hot end of this leg would operate at 1000 C in the vacuum of space. Although Yb14MnSb11 shows the potential to double the value of the thermoelectric figure of merit (zT) over that of Si-Ge at 1000 C, it suffers from a high sublimation rate at elevated temperatures and would require a coating in order to survive the required RTG lifetime of 14 years. The purpose of the present work is to measure the sublimation rate of Yb14MnSb11 and to investigate sublimation suppression for this material. This paper reports on the sublimation rate of Yb14MnSb11 at 1000 C (approximately 3 x 10(exp -3) grams per square centimeter hour) and efforts to reduce the sublimation rate with an in situ grown Yb2O3 layer. Despite the success in forming thin, dense, continuous, and adherent oxide scales on Yb14MnSb11, the scales did not prove to be sublimation barriers.

  9. Flashlamp-pumped Ho:Tm:Cr:LuAG laser

    NASA Technical Reports Server (NTRS)

    Jani, Mahendra G. (Inventor); Barnes, Norman P. (Inventor); Murray, Keith E. (Inventor); Kokta, Milan R. (Inventor)

    1997-01-01

    A room temperature solid-state laser is provided. A laser crystal is disposed in a laser cavity. The laser crystal has a LuAG host material doped with a concentration of about 0.35% Ho ions, about 5.57% Tm ions and at least about 1.01% Cr ions. A broadband energizing source such as a flashlamp is disposed transversely to the laser crystal to energize the Ho ions, Tm ions and Cr ions.

  10. Spectroscopic and lasing properties of Ho:Tm:LuAG

    NASA Technical Reports Server (NTRS)

    Barnes, Norman P.; Filer, Elizabeth D.; Naranjo, Felipe L.; Rodriguez, Waldo J.; Kokta, Milan R.

    1993-01-01

    Ho:Tm:LuAG has been grown, examined spectroscopically, and lased at 2.1 microns. Ho:Tm:LuAG was selected for this experimental investigation when quantum-mechanical modeling predicted that it would be a good laser material for Ho laser operation on one of the 5I7 to 5I8 transitions. Lasing was achieved at 2.100 microns, one of the three wavelengths predicted to be most probable for laser action.

  11. Luminescence studies on Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses for WLED applications

    NASA Astrophysics Data System (ADS)

    Vijayakumar, M.; Uma, V.; Arunkumar, S.; Marimuthu, K.

    2015-06-01

    Dy3+ and Dy3+:Eu3+ co-doped boro-phosphate glasses have been prepared and optically characterized using absorption, luminescence and decay measurements. The Nephelauxetic ratios (β), Bonding parameters (δ) and Judd-Ofelt (JO) intensity parameters Ωλ (λ = 2, 4 and 6) were calculated to study the nature of the environment around the RE3+ ions in the prepared glasses. The yellow to blue (Y/B) intensity ratio and the chromaticity color coordinates were calculated from the luminescence measurements. The lifetimes of the 4F9/2 excited level were measured using decay curves and is found to decrease in the Dy3+:Eu3+ co-doped glass due to the occurrence of resonant energy transfer between Dy3+-Eu3+ ions and the non-exponential decay rates have been fitted with Inokuti-Hirayama (IH) model. The decay curves are well fitted for S= 6 suggesting that the interaction between active ions for the energy transfer is of dipole-dipole nature.

  12. Calibration of the EU Oxybarometer for Nakhlites

    NASA Technical Reports Server (NTRS)

    Makishima, J.; McKay, G.; Le, L.; Miyamoto; Mikouchi, T.

    2006-01-01

    Martian meteorites have various characteristics, which are direct clues to understanding the petrogenesis of Mars rocks. The variation in oxidation state among the Martian meteorites must have important implications for redox conditions of the Martian crust/mantle and overall differentiation on Mars. Wadhwa [1] and Herd et al. [2] reported that Martian basalts were formed under a range of oxidation states, suggesting complex petrogenesis processes. The nakhlites, which have rather different characteristics from basaltic shergottites, may give us additional clues to Martian petrogenesis. The oxidation states of meteorites are usually described by the oxygen fugacity (fO2) under which the meteorites crystallized. One of the methods to estimate the oxygen fugacity is the depth of Eu anomaly. Eu(2+)/Eu(3+) is determined by the oxygen fugacity and partitioning is different for Eu(2+) and Eu(3+). Therefore, the depth of Eu anomaly in a mineral is a function of the oxygen fugacity and the Eu2+/Eu3+ in the melt from which the mineral crystallized. This method has some advantages over another major method, the two-oxide oxybarometer [3], which can more easily be affected by subsolidus processes. The Eu oxybarometer can analyze the cores of the earliest formed crystals in Martian meteorites, which means it can give us a better indication of the oxygen fugacity of the parent melt. The calibration of the Eu oxybarometer has been done with the basaltic shergottites before [4]. However, it has never been applied to nakhlites (Oe et al. [5] measured the depth of Eu anomaly in the synthetic pyroxene only at QFM). Partition coefficients are strongly affected by phase compositions, especially pyroxene Ca content and melt Al content [e.g., 5,6]. The composition of nakhlite pyroxene is rather different from basaltic shergottite pyroxene. Thus, there may be problems in applying the Eu oxybarometer calibration for the basaltic shergottites [7] to nakhlites. Thus, we report in this

  13. Traffic at the tmRNA Gene

    PubMed Central

    Williams, Kelly P.

    2003-01-01

    A partial screen for genetic elements integrated into completely sequenced bacterial genomes shows more significant bias in specificity for the tmRNA gene (ssrA) than for any type of tRNA gene. Horizontal gene transfer, a major avenue of bacterial evolution, was assessed by focusing on elements using this single attachment locus. Diverse elements use ssrA; among enterobacteria alone, at least four different integrase subfamilies have independently evolved specificity for ssrA, and almost every strain analyzed presents a unique set of integrated elements. Even elements using essentially the same integrase can be very diverse, as is a group with an ssrA-specific integrase of the P4 subfamily. This same integrase appears to promote damage routinely at attachment sites, which may be adaptive. Elements in arrays can recombine; one such event mediated by invertible DNA segments within neighboring elements likely explains the monophasic nature of Salmonella enterica serovar Typhi. One of a limited set of conserved sequences occurs at the attachment site of each enterobacterial element, apparently serving as a transcriptional terminator for ssrA. Elements were usually found integrated into tRNA-like sequence at the 3′ end of ssrA, at subsites corresponding to those used in tRNA genes; an exception was found at the non-tRNA-like 3′ end produced by ssrA gene permutation in cyanobacteria, suggesting that, during the evolution of new site specificity by integrases, tropism toward a conserved 3′ end of an RNA gene may be as strong as toward a tRNA-like sequence. The proximity of ssrA and smpB, which act in concert, was also surveyed. PMID:12533482

  14. Effect of silver nanoparticles on the 1.53 μm fluorescence in Er3+/Yb3+ codoped tellurite glasses

    NASA Astrophysics Data System (ADS)

    Wu, Libo; Zhou, Yaxun; Zhou, Zizhong; Cheng, Pan; Huang, Bo; Yang, Fengjing; Li, Jun

    2016-07-01

    Improving the spectroscopic properties of rare earth (RE) doped glass materials is a challenging task. In the present work the metallic silver nanoparticles (Ag NPs) were embedded into Er3+/Yb3+ codoped tellurite glasses with composition TeO2-Bi2O3-TiO2, prepared using melt-quenching and subsequent heat-treated techniques, and the improved effect of Ag NPs on the 1.53 μm band fluorescence of Er3+ ions was investigated. About 24 h heat-treatment of Er3+/Yb3+ codoped tellurite glass containing 1 mol % amount of AgNO3 at the temperature 370 °C yielded the well-dispersed and near-spherical Ag NPs with ∼11.4 nm average diameter as evidenced by transmission electron microscopy (TEM) image. The intense 1.53 μm band fluorescence was observed in the prepared Er3+/Yb3+ codoped tellurite glasses under the excitation of 980 nm and was further improved with the presence of Ag NPs in the glass matrix, which is attributed to the enhanced local electric field around doped RE ions induced by Ag NPs and the possible energy transfer from Ag NPs to Er3+ ions. The enhanced local electric field was well demonstrated by comparing the variation of emission spectra of hypersensitive probe Eu3+ ions in tellurite glasses with and without Ag NPs. From the Judd-Ofelt analysis, it was also found that the value of Ω6 intensity parameter increased slightly with the increase of Ag NPs concentration in a certain range, also confirming the possibility of realizing strong fluorescence emission. In addition, the amorphous structural nature was demonstrated by the measured X-ray diffraction (XRD) patterns with no sharp diffraction peak. The enhanced 1.53 μm band fluorescence indicates that the Er3+/Yb3+ codoped tellurite glass with an appropriate amount of Ag NPs is a promising candidate for the development of Er3+-doped fiber amplifiers (EDFAs) applied in the WDM systems.

  15. Efficient Yb³⁺:CaGdAlO₄ bulk and femtosecond-laser-written waveguide lasers.

    PubMed

    Hasse, Kore; Calmano, Thomas; Deppe, Bastian; Liebald, Christoph; Kränkel, Christian

    2015-08-01

    We report on, to the best of our knowledge, the first fs-laser-written waveguide laser in Yb3+:CaGdAlO4 (Yb:CALGO). With Yb:CALGO crystals grown in our labs, we obtained a slope efficiency of 69% and up to 2.4 W of continuous wave (cw) output power in a waveguide-laser configuration. Moreover, bulk laser experiments with Yb:CALGO were performed, and slope efficiencies up to 73%, optical-to-optical efficiencies of 65%, and maximum cw output powers of 3.3 W were reached. These are the highest efficiencies in the laser configuration with Yb:CALGO.

  16. Experimental evidence for the formation of divalent ytterbium in the photodarkening process of Yb-doped fiber lasers.

    PubMed

    Rydberg, S; Engholm, M

    2013-03-25

    In this work we present experimental evidence that the valence instability of the ytterbium ion play a key role for the observed photodarkening mechanism in Yb-doped fiber lasers. Luminescence and excitation spectroscopy performed on UV irradiated Yb/Al doped silica glass preforms and near-infrared diode pumped photodarkened fibers show a concentration increase of Yb(2+) ions. A concentration decrease in Yb(3+) could also be observed for the UV irradiated preform. The findings contribute to an increased understanding of the kinetic processes related to photodarkening in Yb-doped high power fiber lasers.

  17. Study of Eu{sup 3+} → Eu{sup 2+} reduction in BaAl{sub 2}O{sub 4}:Eu prepared in different gas atmospheres

    SciTech Connect

    Rezende, Marcos V. dos S.; Valerio, Mário E.G.; Jackson, Robert A.

    2015-01-15

    Highlights: • The effect of different gas atmospheres on the Eu reduction process was studied. • The Eu reduction was monitored analyzing XANES region at the Eu L{sub III}-edge. • Hydrogen reducing agent are the most appropriate gas for Eu{sup 2+} stabilization. • Only a part of the Eu ions can be stabilized in the divalent state. • A model of Eu reduction process is proposed. - Abstract: The effect of different gas atmospheres such as H{sub 2}(g), synthetic air, carbon monoxide (CO) and nitrogen (N{sub 2}) on the Eu{sup 3+} → Eu{sup 2+} reduction process during the synthesis of Eu-doped BaAl{sub 2}O{sub 4} was studied using synchrotron radiation. The Eu{sup 3+} → Eu{sup 2+} reduction was monitored analyzing XANES region when the sample are excited at the Eu L{sub III}-edge. The results show that the hydrogen reducing agent are the most appropriate gas for Eu{sup 2+} stabilization in BaAl{sub 2}O{sub 4} and that only a part of the Eu ions can be stabilized in the divalent state. A model of Eu reduction process, based on the incorporation of charge compensation defects, is proposed.

  18. Magnetic and Fermi Surface Properties of Ferromagnets EuPd2 and EuPt2

    NASA Astrophysics Data System (ADS)

    Nakamura, Ai; Akamine, Hiromu; Ashitomi, Yousuke; Honda, Fuminori; Aoki, Dai; Takeuchi, Tetsuya; Matsubayashi, Kazuyuki; Uwatoko, Yoshiya; Tatetsu, Yasutomi; Maehira, Takahiro; Hedo, Masato; Nakama, Takao; Ōnuki, Yoshichika

    2016-08-01

    We succeeded in growing single crystals of the ferromagnets EuPd2 and EuPt2 with the Laves-type cubic structure by the Bridgman method, namely, heating constituting materials in a Mo crucible up to a high temperature of about 1500 °C. The ferromagnetic properties of EuPd2 and EuPt2 with Curie temperatures of 74 and 100 K, respectively, were confirmed from the results of electrical resistivity, specific heat, and magnetization measurements. The ordered moment is 7 μB/Eu, revealing the Eu-divalent ferromagnetism. The present Eu-divalent electronic state is found to be robust against high pressures of up to 8 GPa and is not changed into the Eu-trivalent state. We also carried out de Haas-van Alphen (dHvA) experiments for EuPd2. The detected dHvA branches in EuPd2 are well explained by the relativistic linearized augmented plane wave (RLAPW) energy band calculations for SrPd2, revealing a closed hole Fermi surface and compensated four closed electron Fermi surfaces.

  19. Emerging food safety issues: An EU perspective.

    PubMed

    McEvoy, John D G

    2016-05-01

    Safe food is the right of every citizen of the European Union (EU). A comprehensive and dynamic framework of food and feed safety legislation has been put in place and the EU's executive arm - the European Commission - is responsible for ensuring that the EU member states apply food law consistently. Similarly, the Commission plays an important role in ensuring that imported food meets the EU's stringent food safety standards. Consumer perceptions of unsafe food tend to focus on acute outbreaks of bacterial or viral origin. In recent years there have been a number of diverse food crises associated with fraudulent activity which may (e.g. melamine in dairy products in China) or may not (e.g. the horse meat scandal in the EU) represent a genuine food safety risk. Well publicized incidents of chronic exposure to chemical contamination in the EU (e.g. dioxins in meat and mycotoxins in nuts) have required robust coordinated policy responses from the Commission. Despite the decreasing incidence of non-compliant residues of veterinary medicinal products and banned substances in animal products, EU consumers are increasingly concerned about the use of such products in food-producing animals, including in the context of the build-up of antimicrobial resistance in animals and transfer to humans. The Commission plays a key role in coordination of the EU member states' responses to such incidents, in risk management, and in preparation for emerging issues. This paper focuses on how the EU as a whole has dealt with a number of food crises, and what can be learned from past incidents. Copyright © 2016 John Wiley & Sons, Ltd. PMID:27443205

  20. Yb integrates piRNA intermediates and processing factors into perinuclear bodies to enhance piRISC assembly.

    PubMed

    Murota, Yukiko; Ishizu, Hirotsugu; Nakagawa, Shinichi; Iwasaki, Yuka W; Shibata, Shinsuke; Kamatani, Miharu K; Saito, Kuniaki; Okano, Hideyuki; Siomi, Haruhiko; Siomi, Mikiko C

    2014-07-10

    PIWI-interacting RNAs (piRNAs) direct Piwi to repress transposons and maintain genome integrity in Drosophila ovarian somatic cells. piRNA maturation and association with Piwi occur at perinuclear Yb bodies, the centers of piRNA biogenesis. Here, we show that piRNA intermediates arising from the piRNA cluster flamenco (flam) localize to perinuclear foci adjacent to Yb bodies, termed Flam bodies. RNAi-based screening of piRNA factors revealed that Flam body formation depends on Yb, the core component of Yb bodies, while Piwi and another Yb body component, Armitage, are dispensable for formation. Abolishing the RNA-binding activity of Yb disrupts both Flam bodies and Yb bodies. Yb directly binds flam, but not transcripts from neighboring protein-coding genes. Thus, Yb integrates piRNA intermediates and piRNA processing factors selectively into Flam bodies and Yb bodies, respectively. We suggest that Yb is a key upstream factor in the cytoplasmic phase of the piRNA pathway in ovarian somatic cells. PMID:24953657

  1. Effects of gamma-irradiation and air annealing on Yb-doped Y3Al5O12 single crystal.

    PubMed

    Zeng, Xionghui; Xu, Xiaodong; Wang, Xiaodan; Zhao, Zhiwei; Zhao, Guangjun; Xu, Jun

    2008-03-01

    The effects of gamma-irradiation on the air-annealed 10at.% Yb:Y(3)Al(5)O(12) (YAG) and air annealing on the gamma-irradiated 10at.% Yb:YAG have been studied by the difference absorption spectra before and after treatment. The gamma-irradiation and air annealing led to opposite changes of the absorption properties of the Yb:YAG crystal. After air annealing, the gamma-irradiation induced centers were totally removed and the concentration of Fe(3+) and Yb(3+) were lightly increased. For the first time, the gamma-irradiation induced valence changes between Yb(3+) and Yb(2+) ions in Yb:YAG crystals have been observed.

  2. Elevated serum dehydroepiandrosterone sulfate levels in practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs.

    PubMed

    Glaser, J L; Brind, J L; Vogelman, J H; Eisner, M J; Dillbeck, M C; Wallace, R K; Chopra, D; Orentreich, N

    1992-08-01

    Serum dehydroepiandrosterone sulfate (DHEA-S) levels were measured in 270 men and 153 women who were experienced practitioners of the Transcendental Meditation (TM) and TM-Sidhi programs, mental techniques practiced twice daily, sitting quietly with the eyes closed. These were compared according to sex and 5-year age grouping to 799 male and 453 female nonmeditators. The mean DHEA-S levels in the TM group were higher in all 11 of the age groups measured in women and in 6 of 7 5-year age groups over 40 in men. There were no systematic differences in younger men. Simple regression using TM-group data revealed that this effect was independent of diet, body mass index, and exercise. The mean TM-group levels measured in all women and in the older men were generally comparable to those of nonmeditator groups 5 to 10 years younger. These findings suggest that some characteristics of TM practitioners are modifying the age-related deterioration in DHEA-S secretion by the adrenal cortex.

  3. Microwave sintering of Yb:YAG transparent laser ceramics

    NASA Astrophysics Data System (ADS)

    Esposito, Laura; Piancastelli, Andreana; Bykov, Yury; Egorov, Sergei; Eremeev, Anatolii

    2013-02-01

    Reactive sintering of YAG based ceramics is generally performed under high vacuum in graphite-free furnaces in order to guarantee the elimination of pores and absence of any contamination. An alternative densification technique is the field assisted process such as spark plasma sintering and microwave sintering. Both of these methods are characterized by very fast heating rates, low sintering temperatures and short sintering times. The microwave sintering process is different from electric resistance heating since heat is generated in the bulk of the powder compact through electromagnetic radiation absorption and creates within its body uniform temperature distribution. Microwave sintering of laser ceramics is advantageously distinguished by the absence of any elements having high temperature such as electric heaters or dies which materials can contaminate the sintered parts. In addition, the inverse temperature distribution that exists within the body under volumetric microwave heating is favorable for elimination of porosity. Microwave sintering of Yb:YAG samples were tested and the obtained results are presented. The samples were sintered on a gyrotron-based system operating at a frequency of 24 GHz with microwave power up to 6 kW. Reactive sintering of YAG doped with 1.0, 5.0, and 9.8 at.% Yb2O3 was performed in different temperature-time regimes. The microstructure and the optical transmittance of the obtained samples were compared to those of samples obtained by conventional high vacuum sintering.

  4. (Gd,Yb,Tb)PO4 up-conversion nanocrystals for bimodal luminescence-MR imaging

    NASA Astrophysics Data System (ADS)

    Debasu, Mengistie L.; Ananias, Duarte; Pinho, Sonia L. C.; Geraldes, Carlos F. G. C.; Carlos, Luís D.; Rocha, João

    2012-07-01

    Up-conversion (Gd,Yb,Tb)PO4 materials and their potential for bimodal imaging have received little attention in the literature. Herein, we report the first study on the up-conversion emission of (Gd,Yb,Tb)PO4 nanocrystals synthesized via a hydrothermal method at 150 °C. These materials exhibit ultraviolet, blue and green up-conversion emissions upon excitation with a 980 nm continuous wave laser diode. The intensity of the blue-emission band at 479 nm, ascribed to the cooperative up-conversion emission of a pair of excited Yb3+ ions, depends on the Yb3+/Tb3+ concentration ratio, calcination temperature and particle size. Strong green up-conversion emission of Tb3+ is observed at 543 nm for the 5D4 --> 7F5 transition. Relaxometry measurements reveal that the nanocrystals are efficient T2-weighted (negative) contrast agents which, combined with visible-light emission generated by infrared excitation, affords them considerable potential for being used in bimodal, photoluminescence-magnetic resonance, imaging.Up-conversion (Gd,Yb,Tb)PO4 materials and their potential for bimodal imaging have received little attention in the literature. Herein, we report the first study on the up-conversion emission of (Gd,Yb,Tb)PO4 nanocrystals synthesized via a hydrothermal method at 150 °C. These materials exhibit ultraviolet, blue and green up-conversion emissions upon excitation with a 980 nm continuous wave laser diode. The intensity of the blue-emission band at 479 nm, ascribed to the cooperative up-conversion emission of a pair of excited Yb3+ ions, depends on the Yb3+/Tb3+ concentration ratio, calcination temperature and particle size. Strong green up-conversion emission of Tb3+ is observed at 543 nm for the 5D4 --> 7F5 transition. Relaxometry measurements reveal that the nanocrystals are efficient T2-weighted (negative) contrast agents which, combined with visible-light emission generated by infrared excitation, affords them considerable potential for being used in bimodal

  5. Passive mode-locking of acentric Yb-doped borate crystals

    NASA Astrophysics Data System (ADS)

    Petrov, V.; Mateos, X.; Schmidt, A.; Rivier, S.; Griebner, U.; Zhang, H.; Wang, J.; Li, J.; Liu, J.

    2010-05-01

    Passive mode locking of the self-frequency doubling Yb:YAB and Yb:YCOB crystals with a saturable absorber mirror is studied at the fundamental wavelength with diode pumping. All essential polarization orientations including the self-frequency doubling configuration are considered. For the first time sub-90 fs pulses at the fundamental are obtained with both materials and the improvement in terms of pulse length in comparison to previous work is about 2.3 times (Yb:YAB) and 2.8 times (Yb:YCOB). The Yb:YAB laser generates pulses as short as 87 fs at 1050 nm with a 0.4% output coupler. The shortest pulses (76 fs) are obtained with a Y-cut Yb:YCOB for E ∥ Z. With an output coupler of 0.4% the oscillation wavelength is 1056 nm. For E ∥ X the mode-locked Yb:YCOB laser operates on a different Stark transition (at longer wavelengths) than for E ∥ gg and E ∥ Z.

  6. Investigation of Er3+, Yb3+, Nd3+ doped yttrium calcium oxyborate for photon upconversion applications

    NASA Astrophysics Data System (ADS)

    Kalidasan, M.; Baskar, K.; Dhanasekaran, R.

    2016-07-01

    In this work, investigation have been done on polycrystalline yttrium calcium oxyborate (YCa4O(BO3)3) for the realization of existence of second harmonic generation and other photon upconversion processes as concurrent effect with the aid of Er, Yb, Nd trivalent lanthanide ions. Pure, Er:Yb co-doped and Er:Yb:Nd triply-doped YCa4O(BO3)3 samples were prepared through solid state reaction and the phase identification has been done using powder X-ray diffraction spectral analysis. FTIR spectra show that the dopants increases the absorption of functional groups and modifies the lattice vibrational modes of YCa4O(BO3)3. The spectral overlap of optical absorption bands of Er3+, Yb3+, Nd3+ ions in 840 nm-1070 nm region indicates the prospect of energy transfer between these ions. The photoluminescence spectrum of Er:Yb:Nd triply doped sample show good enhancement compared to pure and Er:Yb co-doped YCa4O(BO3)3 samples. In the photon upconversion test carried out using 1064 nm Nd:YAG laser YCa4O(BO3)3:Er:Yb:Nd sample produced green light with efficiency higher than the other two samples. Surface morphology of the samples was recorded using field emission scanning electron microscope and analysed. The elemental composition of the samples has been confirmed by energy dispersive X-ray spectral analysis.

  7. Synthesis and tunable luminescent properties of Eu-doped Ca2NaSiO4F - Coexistence of the Eu2+ and Eu3+ centers

    NASA Astrophysics Data System (ADS)

    Xie, Mubiao; Li, Dongyu; Zhu, Guoxian; Pan, Rongkai; Fu, Xionghui

    Novel phosphors Ca2NaSiO4F:Eu were synthesized successfully by the conventional solid-state method in CO atmosphere, and their spectroscopic properties in UV-vis region were investigated. The photoluminescence properties show that Eu3+ ions were partially reduced to Eu2+ in Ca2NaSiO4F. As a result of radiation and re-absorption energy transfer from Eu2+ to Eu3+, both Eu2+ bluish-green emission at around 520 nm and Eu3+ red emission are observed in the emission spectra under the n-UV light excitation. Furthermore, the ratio between Eu2+ and Eu3+ emissions varies with increasing content of overall Eu. Because relative intensity of the red component from Eu3+ became systematically stronger, white light emission can be realized by combining the emission of Eu2+ and Eu3+ in a single host lattice under n-UV light excitation. These results indicate that the Ca2NaSiO4F:Eu phosphors have potential applications as a n-UV convertible phosphor for light-emitting diodes.

  8. Formation, optical properties, and electronic structure of thin Yb silicide films on Si(111)

    NASA Astrophysics Data System (ADS)

    Galkin, N. G.; Maslov, A. M.; Polyarnyi, V. O.

    2005-06-01

    Continuous very thin (2.5-3.0 nm) and thin (16-18 nm) ytterbium suicide films with some pinhole density (3×107- 1×108 cm-2) have been formed on Si(111) by solid phase epitaxy (SPE) and reactive deposition epitaxy (RDE) growth methods on templates. The stoichiometric ytterbium suicide (YbSi2) formation has shown in SPE grown films by AES and EELS data. Very thin Yb suicide films grown by RDE method had the silicon enrichment in YbSi2 suicide composition. The analysis of LEED data and AFM imaging has shown that ytterbium suicide films had non-oriented blocks with the polycrystalline structure. The analysis of scanning region length dependencies of the root mean square roughness deviation (σR(L)) for grown suicide films has shown that the formation of ytterbium suicide in SPE and RDE growth methods is determined by the surface diffusion of Yb atoms during the three-dimensional growth process. Optical functions (n, k, α, ɛ1, ɛ2, Im ɛ1-1, neff, ɛeff) of ytterbium silicide films grown on Si(1 1 1) have been calculated from transmittance and reflectance spectra in the energy range of 0.1-6.2 eV. Two nearly discrete absorption bands have been observed in the electronic structure of Yb silicide films with different composition, which connected with interband transitions on divalent and trivalent Yb states. It was established that the reflection coefficient minimum in R-spectra at energies higher 4.2 eV corresponds to the state density minimum in Yb suicide between divalent and trivalent Yb states. It was shown from optical data that Yb silicide films have the semi-metallic properties with low state densities at energies less 0.4 eV and high state densities at 0.5-2.5 eV.

  9. Efficient Nd3+→Yb3+ energy transfer processes in high phonon energy phosphate glasses for 1.0 μm Yb3+ laser

    NASA Astrophysics Data System (ADS)

    Rivera-López, F.; Babu, P.; Basavapoornima, Ch.; Jayasankar, C. K.; Lavín, V.

    2011-06-01

    Efficient Nd3+→Yb3+ resonant and phonon-assisted energy transfer processes have been observed in phosphate glasses and have been studied using steady-state and time-resolved optical spectroscopies. Results indicate that the energy transfer occurs via nonradiative electric dipole-dipole processes and is enhanced with the concentration of Yb3+ acceptor ions, having an efficiency higher than 75% for the glass doped with 1 mol% of Nd2O3 and 4 mol% of Yb2O3. The luminescence decay curves show a nonexponential character and the energy transfer microscopic parameter calculated with the Inokuti-Hirayama model gives a value of 240 × 10-40 cm6 s-1, being one of the highest reported in the literature for Nd3+-Yb3+ co-doped matrices. From the steady-state experimental absorption and emission cross-sections, a general expression for estimating the microscopic energy transfer parameter is proposed based upon the theoretical methods developed by Miyakawa and Dexter and Tarelho et al. This expression takes into account all the resonant mechanisms involved in an energy transfer processes together with other phonon-assisted nonvanishing overlaps. The value of the Nd3+→Yb3+ energy transfer microscopic parameter has been calculated to be 200 × 10-40 cm6 s-1, which is in good agreement with that obtained from the Inokuti-Hirayama fitting. These results show the importance of the nonresonant phonon-assisted Nd3+→Yb3+ energy transfer processes and the great potential of these glasses as active matrices in the development of multiple-pump-channel Yb3+ lasers.

  10. [EuCliD 5TM Clinic Variance Report: a means to improve the safety of patients and staff].

    PubMed

    Oggero, Anna Rita; Palmieri, Veronica; Cerreto, Maria; Manna, Luisa; Lettieri, Iolanda; Napoli, Antonio; Ravone, Virginia; Pelliccia, Francesco; Moretti, Manuela; Parisotto, Maria Teresa

    2010-01-01

    The collection of information about events in the healthcare sector has been documented internationally for more than 25 years. Incident reporting is used for the structured acquisition of information about adverse events to improve patient and healthcare staff safety, prepare corrective action, and prevent event recurrence in the future. The establishment of an incident reporting system requires that the staff involved should be capable of recognizing events which require reporting. The aim of this work was to encourage operators to use the incident reporting system and gradually achieve 100% compliance in the reporting of adverse events and corrective and preventive actions taken. The project was carried out by the staff of one NephroCare dialysis center. The parameters observed were how many times the Variance Report was used, how problems were analyzed, and how many times and by what means the medical and nursing staff took action to correct problems. Ten months from the start of the project 100% reporting was achieved. All selected adverse advents were correctly reported and corrective or preventive action was taken to improve patient care and dialysis center organization. Only effective feedback on the results achieved in terms of safety and tangible improvements by staff will allow the number of reports to be kept high, and maintain participants' compliance with the incident reporting system over the long term.

  11. Thermodynamic and transport properties of single crystalline RCo2Ge2 (R=Y, La–Nd, Sm–Tm)

    SciTech Connect

    Kong, Tai; Cunningham, Charles E.; Taufour, Valentin; Budko, Sergey L.; Buffon, Malinda L.C.; Lin, Xiao; Emmons, Heather; Canfield, Paul C.

    2014-05-01

    Single crystals of RCo2Ge2 (R=Y, La–Nd, Sm–Tm) were grown using a self-flux method and were characterized by room-temperature powder X-ray diffraction; anisotropic, temperature and field dependent magnetization; temperature and field dependent, in-plane resistivity; and specific heat measurements. In this series, the majority of the moment-bearing members order antiferromagnetically; YCo2Ge2 and LaCo2Ge2 are non-moment-bearing. Ce is trivalent in CeCo2Ge2 at high temperatures, and exhibits an enhanced electronic specific heat coefficient due to the Kondo effect at low temperatures. In addition, CeCo2Ge2 shows two low-temperature anomalies in temperature-dependent magnetization and specific heat measurements. Three members (R=Tb–Ho) have multiple phase transitions above 1.8 K. Eu appears to be divalent with total angular momentum L =0. Both EuCo2Ge2 and GdCo2Ge2 manifest essentially isotropic paramagnetic properties consistent with J =S =7/2. Clear magnetic anisotropy for rare-earth members with finite L was observed, with ErCo2Ge2 and TmCo2Ge2 manifesting planar anisotropy and the rest members manifesting axial anisotropy. The experimentally estimated crystal electric field (CEF) parameters B 20 were calculated from the anisotropic paramagnetic θ ab and θ c values and follow a trend that agrees well with theoretical predictions. The ordering temperatures, TNTN, as well as the polycrystalline averaged paramagnetic Curie–Weiss temperature, Θavg, for the heavy rare-earth members deviate from the de Gennes scaling, as the magnitude of both is the highest for Tb, which is sometimes seen for extremely axial systems. Except for SmCo2Ge2, metamagnetic transitions were observed at 1.8 K for all members that ordered antiferromagnetically.

  12. Continuous wave Yb:YCOB cyan lasers with KTP as the sum-frequency converter

    NASA Astrophysics Data System (ADS)

    Lan, Ruijun; Cheng, Hao; Yang, Guang

    2015-12-01

    All-solid-state cyan laser at 500 nm range are reported based on a Yb:YCa4O(BO3)3 (Yb:YCOB) crystal and a type-II phase matched KTiOPO4 (KTP) crystal. The 503 nm cyan laser is obtained by the sum-frequency mixing (SFM) of 974 nm pump wave and 1042 nm fundamental wave. To the best of our knowledge, this is the first cyan laser demonstrated with Yb-doped YCOB crystal. A dual-wavelength laser at 505 and 525 nm is also obtained, which origins from the simultaneous SFM and self-frequency doubling.

  13. Strong excited state absorption (ESA) in Yb-doped fiber lasers

    NASA Astrophysics Data System (ADS)

    Engholm, Magnus; Rydberg, Sara; Hammarling, Krister

    2013-03-01

    Excited state absorption (ESA) measurements performed on Yb-doped silica bers show the onset of a strong absorption band in the visible range. In this work, we perform experiments to investigate the possibility for ESA to be part of the induced optical losses (photodarkening) observed in Yb-doped ber lasers. Our results indicate that an ESA process, from the 2F5/2 excited state manifold in the Yb3+ ion to the charge-transfer state with absorption bands in the UV range, may constitute a transfer route for pump- and laser photons in the near-infrared range.

  14. Incorporation of Yb 3+ ions in multicomponent phase-separated fibre glass preforms

    NASA Astrophysics Data System (ADS)

    Oppo, C. I.; Corpino, R.; Ricci, P. C.; Paul, M. C.; Das, S.; Pal, M.; Bhadra, S. K.; Yoo, S.; Kalita, M. P.; Boyland, A. J.; Sahu, J. K.; Ghigna, P.; d'Acapito, F.

    2012-02-01

    The local environment around Yb 3+ ions in silica-based optic fibre preforms has been studied in specimens with different composition and submitted to different annealing processes. The formation upon annealing of nano-sized particles of YbPO 4 has been evidenced by X-ray Absorption Spectroscopy whereas optical luminescence present Stark-split states in the anti-Stokes lines, typical of a structurally ordered phase. This evidences the preferential location of Yb in highly coordinated phosphate environment, with remarkable effects of such ordered phase on the optical response of the system. This study confirms and extends analogous observations done in previous literature on Erbium in similar glasses.

  15. Yb:FAP and related materials, laser gain medium comprising same, and laser systems using same

    DOEpatents

    Krupke, William F.; Payne, Stephen A.; Chase, Lloyd L.; Smith, Larry K.

    1994-01-01

    An ytterbium doped laser material remarkably superior to all others, including Yb:YAG, comprises Ytterbium doped apatite (Yb:Ca.sub.5 (PO.sub.4).sub.3 F) or Yb:FAP, or ytterbium doped crystals that are structurally related to FAP. The new laser material is used in laser systems pumped by diode pump sources having an output near 0.905 microns or 0.98 microns, such as InGaAs and AlInGaAs, or other narrowband pump sources near 0.905 microns or 0.98 microns. The laser systems are operated in either the conventional or ground state depletion mode.

  16. Czochralski growth of Yb doped oxyapatite for high power laser application

    NASA Astrophysics Data System (ADS)

    Yoshikawa, A.; Fujiwara, C.; Sato, H.; Nishi, T.; Ohta, H.; Fukuda, T.; Waseda, Y.; Boulon, G.; Ito, M.; Guyot, Y.; Lebbou, K.

    2004-09-01

    Ca 8(La,Yb) 2(PO 4) 6O 2 (Yb:CLPA) single crystals with the apatite-type structure could be grown from the melt using the Czochralski method. Grown crystal was 18 mm in diameter and 110 mm in length. It is transparent with slightly blue color. Neither visible inclusion nor crack was observed. Thermal conductivity of Yb:CLPA was calculated from the values of thermal diffusivity, heat capacity measurement and density. Luminescent characterization was carried out from the results of emission, absorption and Raman spectrum.

  17. Synthesis and spectroscopic characterization of Yb3+ in Ca1-XYbXF2+X crystals

    NASA Astrophysics Data System (ADS)

    Ito, M.; Goutaudier, C.; Guyot, Y.; Lebbou, K.; Fukuda, T.; Boulon, G.

    2004-11-01

    Ca1-XYbXF2+X crystals were grown by two different methods: simple melting under CF{4} atmosphere and laser heated pedestal growth (LHPG) method under Ar atmosphere. Spectroscopic characterization has been carried out to separate different crystallographic site in Ca1-XYbXF2+X crystals and to identify Stark's levels of Yb3+ transitions. Experimental decay time dependence of Yb3+ concentration was analyzed by using concentration gradient fiber in order to understand concentration quenching mechanisms. Energy transfer to unexpected rare earth impurities observed by up-conversion emission spectra in visible region under IR Yb3+ ion pumping seems to be an efficient process.

  18. Enhanced 5-µm emission in Tm,Tb: KPb2Br5 and Tm,Nd:KPb2Br5 for mid-infrared laser applications

    NASA Astrophysics Data System (ADS)

    Bluiett, A. G.; Peele, D.; Norman, K.; Brown, E.; Hommerich, U.; Trivedi, S. B.; Zavada, J. M.

    2010-02-01

    We report on the 5 μm emission characteristics and energy transfer properties of Tb3+ doped KPb2Br5 and Nd3+ doped KPb2Br5 sensitized by Tm3+ ions. A series of co-doped samples of Tm,Tb: KPb2Br5 and Tm,Nd: KPb2Br5 samples were prepared from purified starting materials of PbBr2, KBr, and rare earth halides. Resonant excitation into the 3H6 --> 3F4 absorption transition of Tm3+ at ~1760 nm resulted in an enhanced 5 μm emission from Tb3+ and Nd3+ ions in Tm,Tb: KPb2Br5 and Tm,Nd: KPb2Br5, respectively. The existence of energy transfer between Tm --> Tb and Tm --> Nd was further evidenced by the quenching of the emission decay times of the 3F4 --> 3H6 transition of Tm3+ in doubly doped Tm,Tb: KPb2Br5 and Tm,Nd: KPb2Br5 compared to singly doped Tm: KPb2Br5.

  19. Mid-infrared emission characteristics and energy transfer processes in doubly doped Tm, Tb: KPb 2Br 5 and Tm, Nd: KPb 2Br 5

    NASA Astrophysics Data System (ADS)

    Bluiett, A. G.; Peele, D.; Norman, K.; Brown, E.; Hömmerich, U.; Trivedi, S. B.; Zavada, J. M.

    2011-05-01

    We present spectroscopic studies on the ˜5 μm mid-infrared emission and energy transfer properties of Tb 3+ doped KPb 2Br 5 and Nd 3+ doped KPb 2Br 5 sensitized by Tm 3+ ions. A series of co-doped Tm, Tb: KPb 2Br 5 and Tm, Nd: KPb 2Br 5 samples were prepared from purified starting materials of PbBr 2, KBr, and rare-earth bromides. Resonant excitation into the 3H 6 → 3F 4 absorption transition of Tm 3+ at ˜1.76 μm resulted in an enhanced 5 μm emission from Tb 3+ and Nd 3+ ions in Tm, Tb: KPb 2Br 5 and Tm, Nd: KPb 2Br 5, respectively. The existence of energy transfer between Tm → Tb and Tm → Nd in KPB was further evidenced by the quenching of the emission decay times of the 3F 4 → 3H 6 transition of Tm 3+ in doubly doped Tm, Tb: KPb 2Br 5 and Tm, Nd: KPb 2Br 5 compared to singly doped Tm: KPb 2Br 5.

  20. Electronic structure of YbGa1.15Si0:85 and YbGaxGe2-x probed by resonant x-ray emission and photoelectron spectroscopies

    SciTech Connect

    Yamaoka, Hitoshi; Jarrige, Ignace; Tsujii, Naohito; Imai, Motoharu; Lin, Jung-Fu; Matsunami, Masaharu; Eguchi, Ritsuko; Arita, Masashi; Shimada, Kenya; Namatame, Hirofumi; Taniguchi, Masaki; Taguchi, Munetaka; Senba, Yasunori; Ohashi, Haruhiko; Hiraoka, Nozomu; Ishii, Hirofumi; Tsuei, Ku-Ding

    2011-03-31

    We performed an x-ray spectroscopic study combining resonant x-ray emission spectroscopy (RXES) and photoelectron spectroscopy on the superconducting ternary silicide YbGa 1.15 Si 0.85 and nonsuperconducting ternary germanide YbGax Ge2-x (x = 1.0 and 1.1). The Yb valence for all three compounds is found to be about 2.3. In YbGa1.15 Si0.85 no temperature dependence of the Yb valence is observed in the RXES spectra in the temperature range of 7–300 K, while the valence shows a drastic increase under pressure from the Yb2+ state partially including itinerant electrons to the localized Yb3+ state. Differences are observed in the valence-band spectra of the photoelectron spectroscopy between YbGa1.15 Si0.85 and YbGax Ge2-x , which may be attributed to the difference of crystal structure. We conclude that both the crystal structure of the planar GaSi layer in YbGa1.15 Si0.85 and the resultant electronic structure may have a crucial role in the occurrence of superconductivity.

  1. Performance of Landsat TM in ship detection in turbid waters

    NASA Astrophysics Data System (ADS)

    Wu, Guofeng; de Leeuw, Jan; Skidmore, Andrew K.; Liu, Yaolin; Prins, Herbert H. T.

    2009-02-01

    The visible and near infrared bands of Landsat have limitations for detecting ships in turbid water. The potential of TM middle infrared bands for ship detection has so far not been investigated. This study analyzed the performance of the six Landsat TM visible and infrared bands for detecting dredging ships in the turbid waters of the Poyang Lake, China. A colour composite of principal components analysis (PCA) components 3, 2 and 1 of a TM image was used to randomly select 81 dredging ships. The reflectance contrast between ships and adjacent water was calculated for each ship. A z-score and related p-value were used to assess the ship detection performance of the six Landsat TM bands. The reflectance contrast was related to water turbidity to analyze how water turbidity affected the capability of ship identification. The results revealed that the TM middle infrared bands 5 and 7 better discriminated vessels from surrounding waters than the visible and near infrared bands 1-4. A significant relation between reflectance contrast and water turbidity in bands 1-4 could explain the limitations of bands 1-4; while water turbidity has no a significant relation to the reflectance contrast of bands 5 and 7. This explains why bands 5 and 7 detect ships better than bands 1-4.

  2. Metal atom dynamics in superbulky metallocenes: a comparison of (Cp(BIG))2Sn and (Cp(BIG))2Eu.

    PubMed

    Harder, Sjoerd; Naglav, Dominik; Schwerdtfeger, Peter; Nowik, Israel; Herber, Rolfe H

    2014-02-17

    Cp(BIG)2Sn (Cp(BIG) = (4-n-Bu-C6H4)5cyclopentadienyl), prepared by reaction of 2 equiv of Cp(BIG)Na with SnCl2, crystallized isomorphous to other known metallocenes with this ligand (Ca, Sr, Ba, Sm, Eu, Yb). Similarly, it shows perfect linearity, C-H···C(π) bonding between the Cp(BIG) rings and out-of-plane bending of the aryl substituents toward the metal. Whereas all other Cp(BIG)2M complexes show large disorder in the metal position, the Sn atom in Cp(BIG)2Sn is perfectly ordered. In contrast, (119)Sn and (151)Eu Mößbauer investigations on the corresponding Cp(BIG)2M metallocenes show that Sn(II) is more dynamic and loosely bound than Eu(II). The large displacement factors in the group 2 and especially in the lanthanide(II) metallocenes Cp(BIG)2M can be explained by static metal disorder in a plane parallel to the Cp(BIG) rings. Despite parallel Cp(BIG) rings, these metallocenes have a nonlinear Cpcenter-M-Cpcenter geometry. This is explained by an ionic model in which metal atoms are polarized by the negatively charged Cp rings. The extent of nonlinearity is in line with trends found in M(2+) ion polarizabilities. The range of known calculated dipole polarizabilities at the Douglas-Kroll CCSD(T) level was extended with values (atomic units) for Sn(2+) 15.35, Sm(2+)(4f(6) (7)F) 9.82, Eu(2+)(4f(7) (8)S) 8.99, and Yb(2+)(4f(14) (1)S) 6.55. This polarizability model cannot be applied to predominantly covalently bound Cp(BIG)2Sn, which shows a perfectly ordered structure. The bent geometry of Cp*2Sn should therefore not be explained by metal polarizability but is due to van der Waals Cp*···Cp* attraction and (to some extent) to a small p-character component in the Sn lone pair.

  3. High-spin states in {sup 156}Yb and structure evolutions at large angular momenta in even-A Yb isotopes

    SciTech Connect

    Li, Z. Y.; Hua, H.; Wang, S. Y.; Meng, J.; Li, Z. H.; Li, X. Q.; Xu, F. R.; Liu, H. L.; Zhang, S. Q.; Ye, Y. L.; Jiang, D. X.; Zheng, T.; Ma, L. Y.; Lu, F.; Fan, F. Y.; Han, L. Y.; Wang, H.; Xiao, J.; Chen, D.; Fang, X.

    2008-06-15

    High-spin states of {sup 156}Yb have been studied via the {sup 144}Sm({sup 16}O,4n){sup 156}Yb fusion-evaporation reaction at beam energy 102 MeV. The positive-parity yrast band and negative-parity cascade have been extended up to higher-spin states, respectively. In the present work, the negative-parity sequence above the 25{sup -} state was found to be irregular and fragment into many parallel branches. This pattern may related to the excitation from the nucleon in the Z=64,N=82 core. The characteristics of alignment plot and E-GOS curve for the positive-parity yrast sequence in {sup 156}Yb indicate that this nucleus may undergo an evolution from quasivibrational to quasirotational structure with increasing angular momentum. Based on a systematic summary of the available experimental alignments for the even-A {sup 156,158,160,162,164}Yb isotopes, the structural evolutions induced by the increase in angular momentum, as well as by the change in neutron numbers, in these even-A Yb isotopes have been discussed in comparison with the cranked Woods-Saxon-Strutinsky calculations by means of total-Routhian-surface (TRS) methods.

  4. YB-1 expression promotes epithelial-to-mesenchymal transition in prostate cancer that is inhibited by a small molecule fisetin.

    PubMed

    Khan, Mohammad Imran; Adhami, Vaqar Mustafa; Lall, Rahul Kumar; Sechi, Mario; Joshi, Dinesh C; Haidar, Omar M; Syed, Deeba Nadeem; Siddiqui, Imtiaz Ahmad; Chiu, Shing-Yan; Mukhtar, Hasan

    2014-05-15

    Epithelial-to-mesenchymal transition (EMT) plays an important role in prostate cancer (PCa) metastasis. The transcription/translation regulatory Y-box binding protein-1 (YB-1) is known to be associated with cancer metastasis. We observed that YB-1 expression increased with tumor grade and showed an inverse relationship with E-cadherin in a human PCa tissue array. Forced YB-1 expression induced a mesenchymal morphology that was associated with down regulation of epithelial markers. Silencing of YB-1 reversed mesenchymal features and decreased cell proliferation, migration and invasion in PCa cells. YB-1 is activated directly via Akt mediated phosphorylation at Ser102 within the cold shock domain (CSD). We next identified fisetin as an inhibitor of YB-1 activation. Computational docking and molecular dynamics suggested that fisetin binds on the residues from β1 - β4 strands of CSD, hindering Akt's interaction with YB-1. Calculated free binding energy ranged from -11.9845 to -9.6273 kcal/mol. Plasmon Surface Resonance studies showed that fisetin binds to YB-1 with an affinity of approximately 35 µM, with both slow association and dissociation. Fisetin also inhibited EGF induced YB-1 phosphorylation and markers of EMT both in vitro and in vivo. Collectively our data suggest that YB-1 induces EMT in PCa and identify fisetin as an inhibitor of its activation.

  5. Crossover from a heavy fermion to intermediate valence state in noncentrosymmetric Yb2Ni12(P,As)7

    PubMed Central

    Jiang, W. B.; Yang, L.; Guo, C. Y.; Hu, Z.; Lee, J. M.; Smidman, M.; Wang, Y. F.; Shang, T.; Cheng, Z. W.; Gao, F.; Ishii, H.; Tsuei, K. D.; Liao, Y. F.; Lu, X.; Tjeng, L. H.; Chen, J. M.; Yuan, H. Q.

    2015-01-01

    We report measurements of the physical properties and electronic structure of the hexagonal compounds Yb2Ni12Pn7 (Pn = P, As) by measuring the electrical resistivity, magnetization, specific heat and partial fluorescence yield x-ray absorption spectroscopy (PFY-XAS). These demonstrate a crossover upon reducing the unit cell volume, from an intermediate valence state in Yb2Ni12As7 to a heavy-fermion paramagnetic state in Yb2Ni12P7, where the Yb is nearly trivalent. Application of pressure to Yb2Ni12P7 suppresses TFL, the temperature below which Fermi liquid behavior is recovered, suggesting the presence of a quantum critical point (QCP) under pressure. However, while there is little change in the Yb valence of Yb2Ni12P7 up to 30 GPa, there is a strong increase for Yb2Ni12As7 under pressure, before a near constant value is reached. These results indicate that any magnetic QCP in this system is well separated from strong valence fluctuations. The pressure dependence of the valence and lattice parameters of Yb2Ni12As7 are compared and at 1 GPa, there is an anomaly in the unit cell volume as well as a change in the slope of the Yb valence, indicating a correlation between structural and electronic changes. PMID:26626431

  6. TM digital image products for applications. [computer compatible tapes

    NASA Technical Reports Server (NTRS)

    Barker, J. L.; Gunther, F. J.; Abrams, R. B.; Ball, D.

    1984-01-01

    The image characteristics of digital data generated by LANDSAT 4 thematic mapper (TM) are discussed. Digital data from the TM resides in tape files at various stages of image processing. Within each image data file, the image lines are blocked by a factor of either 5 for a computer compatible tape CCT-BT, or 4 for a CCT-AT and CCT-PT; in each format, the image file has a different format. Nominal geometric corrections which provide proper geodetic relationships between different parts of the image are available only for the CCT-PT. It is concluded that detector 3 of band 5 on the TM does not respond; this channel of data needs replacement. The empty bin phenomenon in CCT-AT images results from integer truncations of mixed-mode arithmetric operations.

  7. Intracellular distribution of TM4SF1 and internalization of TM4SF1-antibody complex in vascular endothelial cells.

    PubMed

    Sciuto, Tracey E; Merley, Anne; Lin, Chi-Iou; Richardson, Douglas; Liu, Yu; Li, Dan; Dvorak, Ann M; Dvorak, Harold F; Jaminet, Shou-Ching S

    2015-09-25

    Transmembrane-4 L-six family member-1 (TM4SF1) is a small plasma membrane-associated glycoprotein that is highly and selectively expressed on the plasma membranes of tumor cells, cultured endothelial cells, and, in vivo, on tumor-associated endothelium. Immunofluorescence microscopy also demonstrated TM4SF1 in cytoplasm and, tentatively, within nuclei. With monoclonal antibody 8G4, and the finer resolution afforded by immuno-nanogold transmission electron microscopy, we now demonstrate TM4SF1 in uncoated cytoplasmic vesicles, nuclear pores and nucleoplasm. Because of its prominent surface location on tumor cells and tumor-associated endothelium, TM4SF1 has potential as a dual therapeutic target using an antibody drug conjugate (ADC) approach. For ADC to be successful, antibodies reacting with cell surface antigens must be internalized for delivery of associated toxins to intracellular targets. We now report that 8G4 is efficiently taken up into cultured endothelial cells by uncoated vesicles in a dynamin-dependent, clathrin-independent manner. It is then transported along microtubules through the cytoplasm and passes through nuclear pores into the nucleus. These findings validate TM4SF1 as an attractive candidate for cancer therapy with antibody-bound toxins that have the capacity to react with either cytoplasmic or nuclear targets in tumor cells or tumor-associated vascular endothelium. PMID:26241677

  8. Graphene Q-switched Yb:KYW planar waveguide laser

    SciTech Connect

    Kim, Jun Wan; Young Choi, Sun; Jun Ahn, Kwang; Yeom, Dong-Il E-mail: rotermun@ajou.ac.kr; Rotermund, Fabian E-mail: rotermun@ajou.ac.kr; Aravazhi, Shanmugam; Pollnau, Markus; Griebner, Uwe; Petrov, Valentin; Bae, Sukang

    2015-01-15

    A diode-pumped Yb:KYW planar waveguide laser, single-mode Q-switched by evanescent-field interaction with graphene, is demonstrated for the first time. Few-layer graphene grown by chemical vapor deposition is transferred onto the top of a guiding layer, which initiates stable Q-switched operation in a 2.4-cm-long waveguide laser operating near 1027 nm. Average output powers up to 34 mW and pulse durations as short as 349 ns are achieved. The measured output beam profile, clearly exhibiting a single mode, agrees well with the theoretically calculated mode intensity distribution inside the waveguide. As the pump power is increased, the repetition rate and pulse energy increase from 191 to 607 kHz and from 7.4 to 58.6 nJ, respectively, whereas the pulse duration decreases from 2.09 μs to 349 ns.

  9. Progress toward 174Yb BEC realization for Quantum Simulation

    NASA Astrophysics Data System (ADS)

    Mun, Jongchul; Lee, Jeongwon; Lee, Jae Hoon; Noh, Jiho

    2015-05-01

    We report the progress in building our experimental setup for 174Yb BEC. The experimental setup consists of the conventional Zeeman slower and new type of magneto-optical trap(MOT), which we propose and demonstrate for alkaline-earth-metal-like atoms. This new type of MOT, which we call core-shell MOT, utilizes both the broad 1S0 -->1P1 transition and the narrow 1S0 -->3P1 transition in two spatialy seperated regions. Experimental implementation of this scheme showed both faster loading and high atom numbers, by more than two orders and one order of magnitude respectively, compared to conventional MOT schemes. We plan to further cool and transfer the atomic sample into a science chamber by displacing an optical dipole trap using an optically compensated zoom-lens. The atoms will be loaded into an optical lattice for quantum simulations.

  10. Development of 171Yb optical lattice clock at KRISS

    NASA Astrophysics Data System (ADS)

    Mun, Jongchul; Park, Chang Yong; Yu, Dai-Hyuk; Lee, Won-Kyu; Eon Park, Sang; Kwon, Taeg Yong; Lee, Sang-Bum

    2012-06-01

    We measured the absolute frequency of the optical clock transition 1S0 (F = 1/2) - 3P0 (F = 1/2) of 171Yb atoms confined in a one-dimensional optical lattice and it was determined to be 518 295 836 590 865.7 (9.2) Hz. The measured frequency was calibrated to the Coordinated Universal Time (UTC) by using an optical frequency comb of which frequency was phase-locked to a hydrogen maser as a flywheel oscillator traceable to the UTC. The magic wavelength was also measured as 394 798.48 (79) GHz. The results are in good agreement with two previous measurements of other institutes within the specified uncertainty of this work.

  11. A new vision of photodarkening in Yb3+-doped fibers

    NASA Astrophysics Data System (ADS)

    Peretti, Romain; Gonnet, Cédric; Jurdyc, Anne-Marie

    2012-02-01

    Yb3+-doped fiber is one of the most promising hosts for high-power fiber lasers [1]. However, in the late 1990s, photodarkening effect, i.e., the creation of color centers induced by light, was observed and reported [2]. Like in other rare-earth-doped materials, a broad visible and near infrared absorption band appears during laser operation, which strongly lowers the laser efficiency. We have shown how thulium impurities, present at the parts-per-billion weights (ppb) level in the raw doping material, can induce UV emission which in turn creates defects responsible for photodarkening in ytterbium-doped continuous-wave fiber lasers [3]. This new vision is not in contradiction with others but it gives for the first time a possible explanation for UV defect creation by an infrared beam.

  12. Doppler-free Yb spectroscopy with the fluorescence spot technique

    SciTech Connect

    Nizamani, Altaf H.; McLoughlin, James J.; Hensinger, Winfried K.

    2010-10-15

    We demonstrate a simple technique to measure the resonant frequency of the 398.9-nm {sup 1}S{sub 0}{leftrightarrow}{sup 1}P{sub 1} transition for the different Yb isotopes. The technique, which works by observing and aligning fluorescence spots, has enabled us to measure transition frequencies and isotope shifts with an accuracy of 60 MHz. We provide wavelength measurements for the transition that differ from previously published work. Our technique also allows for the determination of Doppler-shifted transition frequencies for photoionization experiments when the atomic beam and the laser beam are not perpendicular and furthermore allows us to determine the average velocity of the atoms along the direction of the atomic beam.

  13. Precise curvature measurement of Yb:YAG thin disk

    NASA Astrophysics Data System (ADS)

    Muzik, Jiri; Chyla, Michal; Nagisetty, Siva S.; Miura, Taisuke; Mann, Klaus; Endo, Akira; Mocek, Tomas

    2015-01-01

    We are developing an Yb:YAG thin disk regenerative amplifier operating at 1 kHz repetition rate which should deliver output of 100 W of average power which corresponds to the pulse energy of 100 mJ. In order to achieve such high output energy, large size mode matching on a thin-disk is required to avoid optical damage but on the other hand, larger mode area is more susceptible to the influence of optical phase distortions (OPD's) thus limits achievable pulse energy and beam quality. We developed a compact setup allowing precise measurement of the thin-disk deformations by implementation of a Hartmann-Shack wavefront sensor and a single mode probe laser diode. In comparison to the interferometric measurement methods, our approach brings a number of advantages like simplicity of alignment, compactness and robustness, at the same time keeping the high precision of measurement in a range of few nanometers.

  14. Identification of Candida haemulonii Complex Species: Use of ClinProTools(TM) to Overcome Limitations of the Bruker Biotyper(TM), VITEK MS(TM) IVD, and VITEK MS(TM) RUO Databases.

    PubMed

    Grenfell, Rafaella C; da Silva Junior, Afonso R; Del Negro, Gilda M B; Munhoz, Regina B; Gimenes, Viviane M F; Assis, Diego M; Rockstroh, Anna C; Motta, Adriana L; Rossi, Flavia; Juliano, Luiz; Benard, Gil; de Almeida Júnior, João N

    2016-01-01

    Candida haemulonii is now considered a complex of two species and one variety: C. haemulonii sensu stricto, Candida duobushaemulonii and the variety C. haemulonii var. vulnera. Identification (ID) of these species is relevant for epidemiological purposes and for therapeutic management, but the different phenotypic commercial systems are unable to provide correct species ID for these emergent pathogens. Hence, we evaluated the MALDI-TOF MS performance for the ID of C. haemulonii species, analyzing isolates/strains of C. haemulonii complex species, Candida pseudohaemulonii and Candida auris by two commercial platforms, their databases and softwares. To differentiate C. haemulonii sensu sctricto from the variety vulnera, we used the ClinProTools(TM) models and a single-peak analysis with the software FlexAnalysis(TM). The Biotyper(TM) database gave 100% correct species ID for C. haemulonii sensu stricto, C. pseudohaemulonii and C. auris, with 69% of correct species ID for C. duobushaemulonii. Vitek MS(TM) IVD database gave 100% correct species ID for C. haemulonii sensu stricto, misidentifying all C. duobushaemulonii and C. pseudohaemulonii as C. haemulonii, being unable to identify C. auris. The Vitek MS(TM) RUO database needed to be upgraded with in-house SuperSpectra to discriminate C. haemulonii sensu stricto, C. duobushaemulonii, C. pseudohaemulonii, and C. auris strains/isolates. The generic algorithm model from ClinProTools(TM) software showed recognition capability of 100% and cross validation of 98.02% for the discrimination of C. haemulonii sensu stricto from the variety vulnera. Single-peak analysis showed that the peaks 5670, 6878, or 13750 m/z can distinguish C. haemulonii sensu stricto from the variety vulnera.

  15. NIR emission from Yb3+-Er3+ ions in Y2Sn2O7 host

    NASA Astrophysics Data System (ADS)

    Nigam, Sandeep; Sarkar, Kaustabh; Prasad, A. I.; Sudarsan, V.; Vatsa, R. K.

    2015-06-01

    Er and Yb-Er co-doped Y2Sn2O7 both in the bulk and nano-size dimensions were prepared via co-precipitation method and investigated for their photoluminescence properties. Characteristic near Infra-Red (NIR) emission at 1530 nm due to4I13/2→4I15/2 transition of Er3+ was observed in both bulk and nanoparticles of Er doped as well as Yb-Er co-doped Y2Sn2O7. Intensity of emission improves systematically with increase in heat treatment temperature and the bulk sample show improved luminescence with crystal field splitting. Co-doping Y2Sn2O7: Er with Yb3+ ions enhances the NIR emission intensity from Er3+ ion, which is attributed to energy transfer. Excitation spectra also revealed the back energy transfer from Er3+ to Yb3+ ion.

  16. Discrete-fibre subpicosecond oscillator-amplifier based on a Yb:KYW laser

    SciTech Connect

    Kobtsev, S M; Kukarin, S V

    2007-11-30

    A hybrid subpicosecond system based on a Yb:KYW laser and a Yb fibre amplifier made by using the GTWave technology is studied. The system pumped by the 980-nm, 12-W cw radiation emits 0.9-ps, 40-nJ pulses at a pulse repetition rate of 100 MHz and an average power of 4 W. The central emission wavelength of the system can be tuned in the pulsed regime from 1038 to 1053 nm and from 1030 to 1070 nm in the cw regime. The gain of the Yb fibre GTWave amplifier is measured for the first time within the tuning range of the Yb:KYW laser. (lasers)

  17. Diytterbium(II) lithium indium(III) digermanide, Yb2LiInGe2

    PubMed Central

    You, Tae-Soo; Bobev, Svilen

    2010-01-01

    The title compound, Yb2LiInGe2, a new ordered quaternary inter­metallic phase, crystallizes with the ortho­rhom­bic Ca2LiInGe2 type (Pearson code oP24). The crystal structure contains six crystallographically unique sites in the asymmetric unit, all in special positions with site symmetry .m.. The structure is complex and based on [InGe4] tetra­hedra, which share corners in two directions, forming layers parallel to (001). Yb atoms fill square-pyramidal (Yb1) and octa­hedral (Yb2) inter­stices between the [InGe4/2] layers, while the small Li+ atoms fill tetra­hedral sites. PMID:21578989

  18. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    NASA Astrophysics Data System (ADS)

    Fang, H. S.; Qiu, S. R.; Zheng, L. L.; Schaffers, K. I.; Tassano, J. B.; Caird, J. A.; Zhang, H.

    2008-08-01

    Yb:S-FAP [Yb 3+:Sr 5(PO 4) 3F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF 2-rich melts often encounters cracks during the post-growth cool-down stage. To suppress cracking during cool-down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool-down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented, which produced high-quality, crack-free Yb:S-FAP crystals.

  19. Yb:YAG ceramic-based laser driver for Inertial Fusion Energy (IFE)

    NASA Astrophysics Data System (ADS)

    Vetrovec, John; Copeland, Drew A.; Litt, Amardeep S.

    2016-03-01

    We report on a new class of laser amplifiers for inertial confinement fusion (ICF) drivers based on a Yb:YAG ceramic disk in an edge-pumped configuration and cooled by a high-velocity gas flow. The Yb lasant offers very high efficiency and low waste heat. The ceramic host material has a thermal conductivity nearly 15-times higher than the traditionally used glass and it is producible in sizes suitable for a typical 10- to 20-kJ driver beam line. The combination of high lasant efficiency, low waste heat, edge-pumping, and excellent thermal conductivity of the host, enable operation at 10 to 20 Hz at over 20% wall plug efficiency while being comparably smaller and less costly than recently considered face-pumped alternative drivers using Nd:glass, Yb:S-FAP, and cryogenic Yb:YAG. Scalability of the laser driver over a broad range of sizes is presented.

  20. Optimization of the cooling profile to achieve crack-free Yb:S-FAP crystals

    SciTech Connect

    Fang, H; Qiu, S; Kheng, L; Schaffers, K; Tassano, J; Caird, J; Zhang, H

    2007-08-20

    Yb:S-FAP [Yb{sup 3+}:Sr{sub 5}(PO{sub 4}){sub 3}F] crystals are an important gain medium for diode-pumped laser applications. Growth of 7.0 cm diameter Yb:S-FAP crystals utilizing the Czochralski (CZ) method from SrF{sub 2}-rich melts often encounter cracks during the post growth cool down stage. To suppress cracking during cool down, a numerical simulation of the growth system was used to understand the correlation between the furnace power during cool down and the radial temperature differences within the crystal. The critical radial temperature difference, above which the crystal cracks, has been determined by benchmarking the simulation results against experimental observations. Based on this comparison, an optimal three-stage ramp-down profile was implemented and produced high quality, crack-free Yb:S-FAP crystals.

  1. Centrosome maturation requires YB-1 to regulate dynamic instability of microtubules for nucleus reassembly

    PubMed Central

    Kawaguchi, Atsushi; Asaka, Masamitsu N.; Matsumoto, Ken; Nagata, Kyosuke

    2015-01-01

    Microtubule formation from the centrosome increases dramatically at the onset of mitosis. This process is termed centrosome maturation. However, regulatory mechanisms of microtubule assembly from the centrosome in response to the centrosome maturation are largely unknown. Here we found that YB-1, a cellular cancer susceptibility protein, is required for the centrosome maturation. Phosphorylated YB-1 accumulated in the centrosome at mitotic phase. By YB-1 knockdown, microtubules were found detached from the centrosome at telophase and an abnormal nuclear shape called nuclear lobulation was found due to defective reassembly of nuclear envelope by mis-localization of non-centrosomal microtubules. In conclusion, we propose that YB-1 is important for the assembly of centrosomal microtubule array for temporal and spatial regulation of microtubules. PMID:25740062

  2. Alumina Paste Layer as a Sublimation Suppression Barrier for Yb14MnSb11

    NASA Technical Reports Server (NTRS)

    Paik, Jong-Ah; Caillat, Thierry

    2010-01-01

    Sublimation is a major cause of degradation of thermoelectric power generation systems. Most thermoelectric materials tend to have peak values at the temperature where sublimation occurs. A sublimation barrier is needed that is stable at operating temperatures, inert against thermoelectric materials, and able to withstand thermal cycling stress. A porous alumina paste layer is suitable as a sublimation barrier for Yb14MnSb11. It can accommodate stress generated by the thermal expansion discrepancy between the suppression layer and thermoelectric materials. Sublimation suppression is achieved by filling pores naturally with YbO2, a natural byproduct of sublimation. YbO2 generated during the sublimation of Yb14MnSb11 fills the porous structure of the alumina paste, causing sublimation to decrease with time as the pores become filled.

  3. Combining Yb and Li: Rapid Quantum Degenerate Gas Production and Interacting Mixtures

    NASA Astrophysics Data System (ADS)

    Green, Alaina; Roy, Richard; Bowler, Ryan; Gupta, Subhadeep

    2016-05-01

    We detail a readily adaptable method for optimizing evaporative cooling efficiency in optical dipole traps (ODTs), reducing the production time of quantum degenerate gases. Utilizing the time-averaged 'painting' potential of a rapidly moving laser beam, we dynamically shape the trap over the course of evaporation to produce 174 Yb Bose-Einstein condensates of (0.5-1.0) × 105 atoms in (1.6-1.8) seconds. We also report on interaction studies in the quantum degenerate Bose-Fermi 174 Yb-6 Li mixture in the BEC-BCS crossover. Additionally, we present work on photoassociation spectroscopy on 6 Li-Yb mixtures and the production of YbLi* molecules in a dual magneto-optical trap, a first step toward coherent production of ultracold 2 Σ molecules.

  4. Influence of deposition parameters on residual stress of YbF3 thin film

    NASA Astrophysics Data System (ADS)

    Zhang, Yao-ping; Fan, Jun-qi; Long, Guo-yun

    2016-01-01

    YbF3 was proposed as a substitute for ThF4 in anti-reflection or reflection coatings for the infrared range, and the residual stress of YbF3 thin film using APS plasma ion assisted deposition(PIAD) was studied. From the results, we found the anode voltage of PIAD has a large effect on the residual stress of YbF3 thin film, and the refractive index of YbF3 produced with PIAD was higher than without it, with a possible reason close to packing density. Finally, we produced multi-layer reflection coating on a 260mm diameter mono-crystalline silicon substrate. Its surface contour was approximately 0.240λ (λ=632.8nm), and the absorption was lower than 200ppm, which can satisfy the practical requirement.

  5. Superconductivity of Au-Ge-Yb Approximants with Tsai-Type Clusters

    NASA Astrophysics Data System (ADS)

    Deguchi, Kazuhiko; Nakayama, Mika; Matsukawa, Shuya; Imura, Keiichiro; Tanaka, Katsumasa; Ishimasa, Tsutomu; Sato, Noriaki K.

    2015-02-01

    We report the emergence of bulk superconductivity in Au64.0Ge22.0Yb14.0 and Au63.5Ge20.5Yb16.0 below 0.68 and 0.36 K, respectively. This is the first observation of superconductivity in Tsai-type crystalline approximants of quasicrystals. The Tsai-type cluster center is occupied by Au and Ge ions in the former approximant, and by an Yb ion in the latter. For magnetism, the latter system shows a larger magnetization than the former. To explain this observation, we propose a model that the cluster-center Yb ion is magnetic. The relationship between the magnetism and the superconductivity is also discussed.

  6. High-average-power diode-pumped Yb: YAG lasers

    SciTech Connect

    Avizonis, P V; Beach, R; Bibeau, C M; Emanuel, M A; Harris, D G; Honea, E C; Monroe, R S; Payne, S A; Skidmore, J A; Sutton, S B

    1999-10-01

    A scaleable diode end-pumping technology for high-average-power slab and rod lasers has been under development for the past several years at Lawrence Livermore National Laboratory (LLNL). This technology has particular application to high average power Yb:YAG lasers that utilize a rod configured gain element. Previously, this rod configured approach has achieved average output powers in a single 5 cm long by 2 mm diameter Yb:YAG rod of 430 W cw and 280 W q-switched. High beam quality (M{sup 2} = 2.4) q-switched operation has also been demonstrated at over 180 W of average output power. More recently, using a dual rod configuration consisting of two, 5 cm long by 2 mm diameter laser rods with birefringence compensation, we have achieved 1080 W of cw output with an M{sup 2} value of 13.5 at an optical-to-optical conversion efficiency of 27.5%. With the same dual rod laser operated in a q-switched mode, we have also demonstrated 532 W of average power with an M{sup 2} < 2.5 at 17% optical-to-optical conversion efficiency. These q-switched results were obtained at a 10 kHz repetition rate and resulted in 77 nsec pulse durations. These improved levels of operational performance have been achieved as a result of technology advancements made in several areas that will be covered in this manuscript. These enhancements to our architecture include: (1) Hollow lens ducts that enable the use of advanced cavity architectures permitting birefringence compensation and the ability to run in large aperture-filling near-diffraction-limited modes. (2) Compound laser rods with flanged-nonabsorbing-endcaps fabricated by diffusion bonding. (3) Techniques for suppressing amplified spontaneous emission (ASE) and parasitics in the polished barrel rods.

  7. 75 FR 62767 - Grant of Interim Extension of the Term of U.S. Patent No. 4,919,140; AndaraTM

    Federal Register 2010, 2011, 2012, 2013, 2014

    2010-10-13

    ...,140; Andara TM OFS TM System AGENCY: United States Patent and Trademark Office. ACTION: Notice of... the medical device Andara TM OFS TM System and a method of using the Andara TM OFS TM System. The application indicates that a Humanitarian Device Exemption, HDE 070002, for the medical device Andara TM...

  8. Enhanced rock discrimination using Landsat-5 Thematic Mapper (TM) data

    NASA Technical Reports Server (NTRS)

    Blodget, H. W.; Andre, C. G.; Marcell, R. F.

    1985-01-01

    The application of TM data to rock discrimination is discussed. Sixteen specific terrains derived from geologic maps are examined on TM images of the Arabian shield obtained on Apr. 14, 1984; visual enhancement procedures are applied to the images. The rock types observed in the test site are described; the major sedimentary formations in the test area are laterite and sandstone. The data reveal that the layered rocks in the outcrop consist of a variety of metamorphosed volcanics, metamorphosed sediments, and amphibolite, and the intrusive complex is composed of several classes of mafic and acidic rocks.

  9. Optimizing Yb concentration of fiber amplifiers in the presence of transverse modal instabilities and photodarkening.

    PubMed

    Lægsgaard, Jesper

    2016-03-10

    The Yb concentration of double-clad optical fiber amplifiers is numerically optimized with respect to maximizing the transverse modal instability threshold in the presence of absorption arising from photodarkening. The pump cladding area is scaled with the Yb concentration to approximately maintain the pump absorption in operation. It is found that approximate analytical expressions can predict the optimized concentration levels found in numerical simulations with sufficient accuracy to be useful in fiber design. PMID:26974790

  10. "Half-sandwich" Yb(III) single-ion magnets with metallacrowns.

    PubMed

    Li, Quan-Wen; Liu, Jun-Liang; Jia, Jian-Hua; Chen, Yan-Cong; Liu, Jiang; Wang, Long-Fei; Tong, Ming-Liang

    2015-06-28

    The first "half-sandwich" Yb(III) single-ion magnets (SIMs) based on [12-MCZn(ii)-4] are reported, in which the central ytterbium ion is coordinated by YbO8 geometry in D4d symmetry. The anisotropic barrier is extracted from the analysis of static, dynamic magnetism and emission spectrum offering an insight into the magneto-optical correlation.

  11. Synthesis, Structure, and Transport Properties of YbSb2Te4 and YbSb4Te7 for Thermoelectric Applications

    NASA Technical Reports Server (NTRS)

    Guloy, Amado S.

    2005-01-01

    Very little work has been done in the Yb-Sb-Te system of compounds. Exploratory synthesis of various compounds in the system has been performed in the search for new thermoelectric materials. The compounds in the system were examined due to the fact that the system is known to act as a concentrated Kondo system, a heavy fermion. Heavy fermions are known to possess high densities of state which are useful in thermoelectric applications. TWO compounds in the system, YbSb2Te4 and YbSb4Te7, have been successfully synthesized in bulk by two methods: low temperature mechanical alloying and high temperature direct synthesis. The Hall mobility, Seebeck coefficient, electrical resistivity, and thermal conductivity were measured on both the unannealed and annealed compounds up to 550 C to determine the dimensionless thermoelectric figure of merit, ZT. The results indicate that both compounds make promising candidates for use in thermoelectric devices.

  12. Spectroscopic characterization of dynamical processes for Tm,Ho:YAG lasers

    NASA Technical Reports Server (NTRS)

    Armagan, G.; Buoncristiani, A. M.; Edwards, W. C.; Inge, A. T.; Dibartolo, B.

    1991-01-01

    The energy transfer processes in Tm,Ho:YAG lasers were investigated in spectral studies and measurements of the temporal response to pulsed excitation. These processes include the population of the 3H4 pump band of Tm, cross-relaxation in Tm, the transfer of energy from Tm to Ho, and various loss mechanisms. It was found that the Tm cross-relaxation is due to a dipole-dipole interaction between Tm ions and that the rate of this process is a function of temperature and ion concentration.

  13. Do supranational EU institutions make a difference? EU asylum law before and after ‘communitarization’

    PubMed Central

    Ripoll Servent, Ariadna; Trauner, Florian

    2014-01-01

    ABSTRACT This article examines whether the empowerment of the European Union's (EU) supranational institutions has had an impact on the development of EU asylum. By systematically investigating EU asylum law before and after ‘communitarization’, it argues that its ‘policy core’ has maintained a high degree of continuity. An advocacy coalition under the leadership of the interior ministers managed to co-opt pivotal actors in the newly empowered European Commission and European Parliament. By contenting themselves with changes of secondary order, these EU institutions accepted and institutionalized the restrictive and weakly integrated core of EU asylum set by the Council in the first negotiation round. Their role and decisions were driven not only by the negotiation dynamics and political expediency, but also by new inter- and intra-institutional norms fostering consensual practices. PMID:26924934

  14. Perceived Distributive Fairness of EU Transfer Payments, Outcome Favorability, Identity, and EU-Tax Compliance.

    PubMed

    Hartner, Martina; Rechberger, Silvia; Kirchler, Erich; Wenzel, Michael

    2011-01-01

    In a representative UK study (N = 1000) the link between distributive fairness perceptions, outcome favorability, identity, and tax compliance was researched in the context of European transfer payments. Results showed that both forms of tax compliance (i.e., individual and collective EU-tax compliance) were influenced by perceived distributive fairness judgments of EU transfer payments. Fairness itself was related to perceived outcome favorability (i.e., whether their own nation benefits from the EU in financial as well as socio-political terms). Additionally, national identifiers (i.e., people identifying with their own nation, but not with Europe) perceived EU membership as unbeneficial in financial as well as in socio-political terms and thus considered the transfer payments as less fair. Dual identifiers (i.e., people identifying with their own nation and with Europe) perceived the socio-political outcomes from EU membership as more beneficial and thus evaluated the transfer payments as fairer.

  15. Kinematics at the intersection of the Garlock and Death Valley fault zones, California: Integration of TM data and field studies. LANDSAT TM investigation proposal TM-019

    NASA Technical Reports Server (NTRS)

    Abrams, Michael; Verosub, Ken

    1987-01-01

    Processing and interpretation of Thematic Mapper (TM) data, extensive field work, and processing of SPOT data were continued. Results of these analyses led to the testing and rejecting of several of the geologic/tectonic hypotheses concerning the continuation of the Garlock Fault Zone (GFZ). It was determined that the Death Valley Fault Zone (DVFZ) is the major through-going feature, extending at least 60 km SW of the Avawatz Mountains. Two 5 km wide fault zones were identified and characterized in the Soda and Bristol Mountains, forming a continuous zone of NW trending faulting. Geophysical measurements indicate a buried connection between the Avawatz and the Soda Mountains Fault Zone. Future work will involve continued field work and mapping at key locations, further analyses of TM data, and conclusion of the project.

  16. Near-Infrared Quantum Cutting in Yb3+ Doped SrMoO4 Phosphors.

    PubMed

    Luo, Xiaobing; Shen, Jun; Huang, He; Xu, Lu; Wang, Zhixiang; Chen, Yang; Li, Li

    2016-04-01

    Efficient near-infrared (NIR) quantum cutting (QC) has been demonstrated in Yb3+ doped SrMoO4 phosphors synthesized by the high-temperature solid-state reaction method. The obtained SrMoO4:Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra and decay lifetime to understand the observed near-infrared quantum cutting phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of SrMoO4 and exhibit good crystallinity. The experimental results showed that the strong visible molybdate (MoO2-(4)) emission around 493 nm and near-infrared (NIR) emission around 1000 nm from Yb3+(2F(5/2)-->2F(7/2)) of SrMoO4:Yb3+ phosphors were observed under ultraviolet (290 nm) excitation. The Yb + concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches as high as 10 mol%. The cooperative energy transfer (CET) mechanism was also discussed in detail. The broadband NIR QC phosphors may possibly have potential application in enhancing the conversion efficiency of solar cells.

  17. Lanthanide near infrared imaging in living cells with Yb3+ nano metal organic frameworks.

    PubMed

    Foucault-Collet, Alexandra; Gogick, Kristy A; White, Kiley A; Villette, Sandrine; Pallier, Agnès; Collet, Guillaume; Kieda, Claudine; Li, Tao; Geib, Steven J; Rosi, Nathaniel L; Petoud, Stéphane

    2013-10-22

    We have created unique near-infrared (NIR)-emitting nanoscale metal-organic frameworks (nano-MOFs) incorporating a high density of Yb(3+) lanthanide cations and sensitizers derived from phenylene. We establish here that these nano-MOFs can be incorporated into living cells for NIR imaging. Specifically, we introduce bulk and nano-Yb-phenylenevinylenedicarboxylate-3 (nano-Yb-PVDC-3), a unique MOF based on a PVDC sensitizer-ligand and Yb(3+) NIR-emitting lanthanide cations. This material has been structurally characterized, its stability in various media has been assessed, and its luminescent properties have been studied. We demonstrate that it is stable in certain specific biological media, does not photobleach, and has an IC50 of 100 μg/mL, which is sufficient to allow live cell imaging. Confocal microscopy and inductively coupled plasma measurements reveal that nano-Yb-PVDC-3 can be internalized by cells with a cytoplasmic localization. Despite its relatively low quantum yield, nano-Yb-PVDC-3 emits a sufficient number of photons per unit volume to serve as a NIR-emitting reporter for imaging living HeLa and NIH 3T3 cells. NIR microscopy allows for highly efficient discrimination between the nano-MOF emission signal and the cellular autofluorescence arising from biological material. This work represents a demonstration of the possibility of using NIR lanthanide emission for biological imaging applications in living cells with single-photon excitation.

  18. Lanthanide near infrared imaging in living cells with Yb3+ nano metal organic frameworks

    PubMed Central

    Foucault-Collet, Alexandra; Gogick, Kristy A.; White, Kiley A.; Villette, Sandrine; Pallier, Agnès; Collet, Guillaume; Kieda, Claudine; Li, Tao; Geib, Steven J.; Rosi, Nathaniel L.; Petoud, Stéphane

    2013-01-01

    We have created unique near-infrared (NIR)–emitting nanoscale metal-organic frameworks (nano-MOFs) incorporating a high density of Yb3+ lanthanide cations and sensitizers derived from phenylene. We establish here that these nano-MOFs can be incorporated into living cells for NIR imaging. Specifically, we introduce bulk and nano-Yb-phenylenevinylenedicarboxylate-3 (nano-Yb-PVDC-3), a unique MOF based on a PVDC sensitizer-ligand and Yb3+ NIR-emitting lanthanide cations. This material has been structurally characterized, its stability in various media has been assessed, and its luminescent properties have been studied. We demonstrate that it is stable in certain specific biological media, does not photobleach, and has an IC50 of 100 μg/mL, which is sufficient to allow live cell imaging. Confocal microscopy and inductively coupled plasma measurements reveal that nano-Yb-PVDC-3 can be internalized by cells with a cytoplasmic localization. Despite its relatively low quantum yield, nano-Yb-PVDC-3 emits a sufficient number of photons per unit volume to serve as a NIR-emitting reporter for imaging living HeLa and NIH 3T3 cells. NIR microscopy allows for highly efficient discrimination between the nano-MOF emission signal and the cellular autofluorescence arising from biological material. This work represents a demonstration of the possibility of using NIR lanthanide emission for biological imaging applications in living cells with single-photon excitation. PMID:24108356

  19. Near-Infrared Quantum Cutting in Yb3+ Doped SrMoO4 Phosphors.

    PubMed

    Luo, Xiaobing; Shen, Jun; Huang, He; Xu, Lu; Wang, Zhixiang; Chen, Yang; Li, Li

    2016-04-01

    Efficient near-infrared (NIR) quantum cutting (QC) has been demonstrated in Yb3+ doped SrMoO4 phosphors synthesized by the high-temperature solid-state reaction method. The obtained SrMoO4:Yb3+ phosphors were characterized by X-ray diffraction (XRD), diffuse reflectance spectra, photoluminescence (PL) spectra and decay lifetime to understand the observed near-infrared quantum cutting phenomena. The XRD results show that all the prepared phosphors can be readily indexed to the pure tetragonal phase of SrMoO4 and exhibit good crystallinity. The experimental results showed that the strong visible molybdate (MoO2-(4)) emission around 493 nm and near-infrared (NIR) emission around 1000 nm from Yb3+(2F(5/2)-->2F(7/2)) of SrMoO4:Yb3+ phosphors were observed under ultraviolet (290 nm) excitation. The Yb + concentration dependence of luminescent properties and lifetimes of both the visible and NIR emissions have also been investigated. The quenching concentration of Yb3+ ions approaches as high as 10 mol%. The cooperative energy transfer (CET) mechanism was also discussed in detail. The broadband NIR QC phosphors may possibly have potential application in enhancing the conversion efficiency of solar cells. PMID:27451655

  20. Growth, structural, thermal, electrical and nonlinear optical properties of Yb3+ doped KTiOPO4

    NASA Astrophysics Data System (ADS)

    Sadhasivam, S.; Perumal, Rajesh Narayana; Ramasamy, P.

    2016-07-01

    The KTiOPO4:Yb (KTP:Yb) crystal has been grown by flux growth at high temperature (~ 1243-1223K). KTP:Yb crystallizes in the orthorhombic crystal system with Pna21 space group. Ytterbium presence was analyzed in the grown crystal by EDAX analysis. The existence of Ti3+ color center has been evaluated using electron paramagnetic spin resonance spectrum. The Raman spectroscopic techniques were used to study the effect of Yb3+ in KTP crystal. Thermal diffusivity, thermal conductivity and specific heat capacity of grown crystal were studied. At low frequency, the dielectric constant decreases sharply in the frequency region of 104 Hz. The electrical conductivity along the [001] is low (9.0435×10-7 S/cm) for 60 kHz at 300 K. The temperature dependent variation of electric conductivity was found for [010] and [001] of KTP:Yb. The effect of Yb3+ doping in second harmonic generation of KTP was studied.

  1. Ammonothermal Synthesis, Crystal Structure, and Properties of the Ytterbium(II) and Ytterbium(III) Amides and the First Two Rare-Earth-Metal Guanidinates, YbC(NH)3 and Yb(CN3H4)3.

    PubMed

    Görne, Arno L; George, Janine; van Leusen, Jan; Dück, Gerald; Jacobs, Philipp; Chogondahalli Muniraju, Naveen Kumar; Dronskowski, Richard

    2016-06-20

    We report the oxidation-controlled synthesis of the ytterbium amides Yb(NH2)2 and Yb(NH2)3 and the first rare-earth-metal guanidinates YbC(NH)3 and Yb(CN3H4)3 from liquid ammonia. For Yb(NH2)2, we present experimental atomic displacement parameters from powder X-ray diffraction (PXRD) and density functional theory (DFT)-derived hydrogen positions for the first time. For Yb(NH2)3, the indexing proposal based on PXRD arrives at R3̅, a = 6.2477(2) Å, c = 17.132(1) Å, V = 579.15(4) Å(3), and Z = 6. The oxidation-controlled synthesis was also applied to make the first rare-earth guanidinates, namely, the doubly deprotonated YbC(NH)3 and the singly deprotonated Yb(CN3H4)3. YbC(NH)3 is isostructural with SrC(NH)3, as derived from PXRD (P63/m, a = 5.2596(2) Å, c = 6.6704(2) Å, V = 159.81(1) Å(3), and Z = 2). Yb(CN3H4)3 crystallizes in a structure derived from the [ReO3] type, as studied by powder neutron diffraction (Pn3̅, a = 13.5307(3) Å, V = 2477.22(8) Å(3), and Z = 8 at 10 K). Electrostatic and hydrogen-bonding interactions cooperate to stabilize the structure with wide and empty channels. The IR spectra of the guanidinates are compared with DFT-calculated phonon spectra to identify the vibrational modes. SQUID magnetometry shows that Yb(CN3H4)3 is a paramagnet with isolated Yb(3+) (4f(13)) ions. A CONDON 2.0 fit was used to extract all relevant parameters. PMID:27248288

  2. Photoluminescence properties and energy levels of RE (RE = Pr, Sm, Er, Tm) in layered-CaZnOS oxysulfide

    SciTech Connect

    Zhang, Zhi-Jun; Feng, Ang; Chen, Xiang-Yang; Zhao, Jing-Tai

    2013-12-07

    RE{sup 3+} (RE = Pr, Sm, Er, Tm)-activated CaZnOS samples were prepared by a solid-state reaction method at high temperature, and their photoluminescence properties were investigated. Doping with RE{sup 3+} (RE = Pr, Sm, Er, Tm) into layered-CaZnOS resulted in typical RE{sup 3+} (RE = Pr, Sm, Er, Tm) f-f line absorptions and emissions, as well as the charge transfer band of Sm{sup 3+} at about 3.3 eV. The energy level scheme containing the position of the 4f and 5d levels of all divalent and trivalent lanthanide ions with respect to the valence and conduction bands of CaZnOS has been constructed based on the new data presented in this work, together with the data from literature on Ce{sup 3+} and Eu{sup 2+} doping in CaZnOS. The detailed energy level scheme provides a platform for interpreting the optical spectra and could be used to comment on the valence stability of the lanthanide ions in CaZnOS.

  3. Thermoelectric and magnetic properties of Yb2MgSi2 prepared by spark plasma sintering method

    NASA Astrophysics Data System (ADS)

    Kubouchi, M.; Hayashi, K.; Miyazaki, Y.

    2016-08-01

    An intermediate-valence compound, Yb2MgSi2, has been prepared using a spark plasma sintering method. The magnetic susceptibility and thermoelectric properties of Yb2MgSi2 are measured in the temperature range from 5 to 300 K. From the magnetic susceptibility results, Yb valence of the Yb2MgSi2 is evaluated. As compared with YbAl3, which is one of the promising thermoelectric materials that can be used at low temperatures, Yb2MgSi2 exhibits a lower absolute value of Seebeck coefficient, higher electrical resistivity, and lower thermal conductivity over the measured temperature range. A maximum dimensionless figure of merit, ZT, of 0.0018 is achieved at around 200 K.

  4. Luminescent and lasing characteristics of heavily doped Yb{sup 3+}:KY(WO{sub 4}){sub 2} crystals

    SciTech Connect

    Kisel', V E; Troshin, A E; Shcherbitskii, V G; Kuleshov, N V; Pavlyuk, A A; Brunner, F; Paschotta, R; Morier-Genoud, F; Keller, U

    2006-04-30

    The luminescence decay times are measured taking into account reabsorption for KY(WO{sub 4}){sub 2}:Yb(KYW:Yb) crystals with atomic concentrations of active ions from 0.2% to 30%. The radiative lifetime of Yb{sup 3+} ions was measured to be 233 {mu}s. The cw output power of 1.46 and 1.62 W was achieved with the slope efficiency 52% and 47% for Yb:KYW lasers with the atomic concentration of Yb{sup 3+} ions equal to 10% and 30%, respectively. Using a semiconductor mirror with a saturable absorber (SESAM) in the passive mode-locking regime, pulses of duration 194 and 180 fs were obtained at wavelengths of 1042 and 1039 nm for crystals with Yb{sup 3+} concentrations equal to 10% and 30%, respectively, the average output power being 0.63 and 0.75 W. (lasers and amplifiers)

  5. Conductively Cooled Ho:Tm:LuLiF Laser Amplifier

    NASA Technical Reports Server (NTRS)

    Bai, Yingxin; Yu, Jirong; Trieu, Bo; Petros, M.; Petzar, Paul; Lee, Hyung; Singh, U.

    2008-01-01

    A conductively-cooled Ho:Tm:LuLiF laser head can amplify 80mJ/340ns probe pulses into 400mJ when the pump pulse energy is close to amplified spontaneous emission (ASE) threshold, 5.6J. For a small signal, the double-pass amplification exceeds 25.

  6. Thortveitite-type Tm2Si2O7

    PubMed Central

    Kahlenberg, Volker; Aichholzer, Paul

    2014-01-01

    Single crystals of dithulium disilicate, Tm2Si2O7, were obtained in flux synthesis experiments in the system SiO2–Tm2O3–LiF at ambient pressure. The compound belongs to the group of sorosilicates, i.e. it is based on [Si2O7]-units and crystallizes in the thortveitite (Sc2Si2O7) structure type. The Tm3+ cation (site symmetry .2.) occupies a distorted octa­hedral site, with Tm—O bond lengths in the range 2.217 (4)–2.289 (4) Å. Each of the octa­hedra shares three of its edges with adjacent [TmO6] groups, resulting in the formation of layers parallel to (001). The individual [SiO4] tetra­hedra are more regular, i.e. the differences between the bond lengths between Si and the bridging and non-bridging O atoms are not very pronounced. The layers containing the octa­hedra and the sheets containing the [Si2O7] groups (point group symmetry 2/m) form an alternating sequence. Linkage is provided by sharing common oxygen vertices. PMID:25161507

  7. Doors to Discovery[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2013

    2013-01-01

    "Doors to Discovery"]TM] is a preschool literacy curriculum that uses eight thematic units of activities to help children build fundamental early literacy skills in oral language, phonological awareness, concepts of print, alphabet knowledge, writing, and comprehension. The eight thematic units cover topics such as nature, friendship, communities,…

  8. Supporting Moral Development: The Virtues Project[TM

    ERIC Educational Resources Information Center

    de Moor, Gerrit

    2011-01-01

    The Virtues Project[TM] was founded in Canada in 1991 by Linda Kavelin Popov, Dan Popov, and John Kavelin who were concerned about the level of violence among families and youth. In studying sacred traditions and cultures around the world, they identified a set of common virtues. These were used to develop a pedagogical model that has applications…

  9. "Headsprout Early Reading" [TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2009

    2009-01-01

    "Headsprout Early Reading"[TM] is an Internet-based supplemental early literacy curriculum consisting of forty 20-minute animated episodes that are designed to teach phonemic awareness, phonics, fluency, vocabulary, and comprehension. The program adapts to a child's responses, providing additional instruction and review if a child does not choose…

  10. Herman Method[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2010

    2010-01-01

    The "Herman Method"[TM] teaches reading in small groups of up to three students. The curriculum provides instruction in phonemic awareness, phonics, fluency, vocabulary, and reading comprehension, while also teaching spelling and writing. It contains 20 modules of instruction through a fifth grade level. Each module includes a reading, spelling,…

  11. CPR[TM]: Adopting an Out-of-Discipline Innovation

    ERIC Educational Resources Information Center

    Strong, Kay E.

    2008-01-01

    Calibrated Peer Review[TM] (CPR) is a web-based instructional tool that encourages "writing gain for students" without adding "grading pain for the instructor!" The use of CPR provides students frequent opportunities to hone both writing as well as peer review skills in a guided environment. And once an assignment is authored, instructors have…

  12. Information Retention from PowerPoint[TM] and Traditional Lectures

    ERIC Educational Resources Information Center

    Savoy, April; Proctor, Robert W.; Salvendy, Gavriel

    2009-01-01

    The benefit of PowerPoint[TM] is continuously debated, but both supporters and detractors have insufficient empirical evidence. Its use in university lectures has influenced investigations of PowerPoint's effects on student performance (e.g., overall quiz/exam scores) in comparison to lectures based on overhead projectors, traditional lectures…

  13. Single-frequency lasing of monolithic Ho,Tm:YLF

    NASA Technical Reports Server (NTRS)

    Koch, Grady J.; Deyst, John P.; Storm, Mark E.

    1993-01-01

    Single-frequency lasing in monolithic crystals of holmium-thulium-doped YLF (Ho,Tm:YLF) is reported. A maximum single-frequency output power of 6 mW at a wavelength of 2.05 microns is demonstrated. Frequency tuning is also described.

  14. An Excel[TM] Model of a Radioactive Series

    ERIC Educational Resources Information Center

    Andrews, D. G. H.

    2009-01-01

    A computer model of the decay of a radioactive series, written in Visual Basic in Excel[TM], is presented. The model is based on the random selection of cells in an array. The results compare well with the theoretical equations. The model is a useful tool in teaching this aspect of radioactivity. (Contains 4 figures.)

  15. Non-explosive actuation for the ORBCOMM (TM) satellite

    NASA Technical Reports Server (NTRS)

    Robinson, Anthony; Courtney, Craig; Moran, Tom

    1995-01-01

    Spool-based non-explosive actuator (NEA) devices are used for three important holddown and release functions during the establishment of the ORBCOMM (TM) constellation. Non-explosive separation nuts are used to restrain and release the 26 individual satellites into low earth orbit. Cable release mechanisms based on the same technology are used to release the solar arrays and antenna boom.

  16. Montessori(TM) Math by Colors [CD Rom.

    ERIC Educational Resources Information Center

    1995

    Montessori(TM) Learning Software programs are purportedly built upon the core concept of the Montessori philosophy, that a major path to intellectual development is through a child's hands and senses. Math by Colors, recommended for ages 4 to 8, encourages hands-on discovery by allowing the child to choose the right color from the assembled paint…

  17. Tilted axis rotation in odd-odd {sup 164}Tm

    SciTech Connect

    Reviol, W.; Riedinger, L.L.; Wang, X.Z.; Zhang, J.Y.

    1996-12-31

    Ten band structures are observed in {sup 164}Tm, among them sets of parallel and anti-parallel couplings of the proton and neutron spins. The Tilted Axis Cranking scheme is applied for the first time to an odd-odd nucleus in a prominent region of nuclear deformation.

  18. VERB [TM] Summer Scorecard: Increasing Tween Girls' Vigorous Physical Activity

    ERIC Educational Resources Information Center

    Alfonso, Moya L.; Thompson, Zachary; McDermott, Robert J.; Colquitt, Gavin; Jones, Jeffery A.; Bryant, Carol A.; Courtney, Anita H.; Davis, Jenna L.; Zhu, Yiliang

    2013-01-01

    Objective: We assessed changes in the frequency of self-reported physical activity (PA) among tween girls exposed and not exposed to the VERB [TM] Summer Scorecard (VSS) intervention in Lexington, Kentucky, during 2004, 2006, and 2007. Methods: Girls who reported 0-1 day per week of PA were classi?ed as having "little or no" PA. Girls who reported…

  19. Magnetization reversal in TmCrO{sub 3}

    SciTech Connect

    Yoshii, Kenji

    2012-11-15

    Highlights: ► We observed two magnetization reversals in TmCrO{sub 3}. ► The reversal at 28 K is attributed to antiparallel coupling between Cr{sup 3+} and Tm{sup 3+}. ► The other reversal originates from spin reorientation. ► Magnetocaloric effect is observed at the spin reorientation temperature. ► Characteristic magnetization switching is demonstrated. -- Abstract: The perovskite chromite TmCrO{sub 3} shows magnetization reversal at two temperatures. The reversal at ∼28 K is attributed to the antiparallel coupling between Tm{sup 3+} and Cr{sup 3+} moments, while that at the lower temperature (∼6–7 K) is rooted in a rotation of the magnetic moments. Magnetocaloric measurements offer a relatively large entropy change (∼4–5 J kg{sup −1} K{sup −1}) at the lower temperature. The reversal at ∼28 K is accompanied by a sign change of an exchange-bias-like field. The absence of the training effect suggests that this behavior is rooted in unidirectional magnetic anisotropy. The existence of the two magnetization reversals offers the characteristic switching of magnetization. For example, the magnetization is flipped without changing the direction of the applied magnetic field.

  20. Fluency Formula[TM]. What Works Clearinghouse Intervention Report

    ERIC Educational Resources Information Center

    What Works Clearinghouse, 2007

    2007-01-01

    "Fluency Formula"[TM] is a supplemental curriculum designed to promote reading fluency for first- through sixth-grade students. The program emphasizes automatic recognition of words, decoding accuracy, and oral expressiveness as the foundation for building reading fluency. A daily 10- to 15-minute lesson is delivered in the classroom. Students…