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Ultrafast Mid-Infrared Intra-Excitonic Response of Individualized Single-Walled Carbon Nanotubes

Description: The quasi-1D confinement and reduced screening of photoexcited charges in single-walled carbon nanotubes (SWNTs) entails strongly-enhanced Coulomb interactions and exciton binding energies. Such amplified electron-hole (e-h) correlations have important implications for both fundamental physics and optoelectronic applications of nanotubes. The availability of"individualized" SWNT ensembles with bright and structured luminescence has rendered specific tube chiralities experimentally acc… more
Date: June 29, 2009
Creator: Wang, Jigang; Graham, Matt W.; Ma, Yingzhong; Fleming, Graham R. & Kaindl, Robert A.
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Partner: UNT Libraries Government Documents Department
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Me-3,2-HOPO Complexes of Near Infra-Red (NIR) Emitting Lanthanides: Efficient Sensitization of Yb(III) and Nd(III) in Aqueous Solution

Description: The synthesis, X-ray structure, solution stability, and photophysical properties of several trivalent lanthanide complexes of Yb(III) and Nd(III) using both tetradentate and octadentate ligand design strategies and incorporating the 1-methyl-3-hydroxy-pyridin-2-one (Me-3,2-HOPO) chelate group are reported. Both the Yb(III) and Nd(III) complexes have emission bands in the Near Infra-Red (NIR) region, and this luminescence is retained in aqueous solution ({Phi}{sub tot}{sup Yb} {approx} 0.09-0.22… more
Date: November 10, 2009
Creator: Moore, Evan G.; Xu, Jide; Dodani, Sheel; Jocher, Christoph; D'Aleo, Anthony; Seitz, Michael et al.
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Partner: UNT Libraries Government Documents Department
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Quest for Environmentally-Benign Ligands for Actinide Separations: Thermodynamic, Spectroscopic, and Structural Characterization of U(VI) Complexes with Oxa-Diamide and Related Ligands

Description: Complexation of U(VI) with N,N,N{prime},N{prime}-tetramethyl-3-oxa-glutaramide (TMOGA) and N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) was studied in comparison with their dicarboxylate analog, oxydiacetic acid (ODA). Thermodynamic parameters, including stability constants, enthalpy and entropy of complexation, were determined by spectrophotometry, potentiometry and calorimetry. Single-crystal X-ray diffractometry, EXAFS spectroscopy, FT-IR absorption and laser-induced luminescence spectroscopy … more
Date: January 5, 2009
Creator: Source, Advanced Light; Tian, Guoxin; Rao, Linfeng; Teat, Simon J. & Liu, Guokui
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Partner: UNT Libraries Government Documents Department
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Crystal growth and scintillation properties of strontium iodide scintillators

Description: Single crystals of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na were grown from anhydrous iodides by the vertical Bridgman technique in evacuated silica ampoules. Growth rates were of the order of 5-30 mm/day. Radioluminescence spectra of SrI{sub 2}:Eu and SrI{sub 2}:Ce/Na exhibit a broad band due to Eu{sup 2+} and Ce{sup 3+} emission, respectively. The maximum in the luminescence spectrum of SrI{sub 2}:Eu is found at 435 nm. The spectrum of SrI{sub 2}:Ce/Na exhibits a doublet peaking at 404 and 435 nm a… more
Date: June 1, 2009
Creator: van Loef, Edgar; Wilson, Cody; Cherepy, Nerine; Payne, Steven; Choong, Woon-Seng; Moses, William W. et al.
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Partner: UNT Libraries Government Documents Department
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Circularly Polarized Luminescence in Enantiopure Europium and Terbium Complexes with Modular, All-Oxygen Donor Ligands

Description: The modular syntheses of three new octadentate, enantiopure ligands are reported, one with the bidentate chelating unit 2-hydroxyisophthalamide (IAM) and two with bidentate 1-hydroxy-2-pyridinone (1,2-HOPO) units. A new design principle is introduced for the chiral, non-racemic hexamines which constitute the central backbones for the presented class of ligands. The terbium(III) complex of the IAM ligand, as well as the europium(III) complexes of the 1,2-HOPO ligands, are synthesized and charact… more
Date: June 4, 2009
Creator: Seitz, Michael; Do, King; Ingram, Andrew; Moore, Evan; Muller, Gilles & Raymond, Kenneth
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Partner: UNT Libraries Government Documents Department
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Using the Antenna Effect as a Spectroscopic Tool; Photophysics and Solution Thermodynamics of the Model Luminescent Hydroxypyridonate Complex [EuIII(3,4,3-LI(1,2-HOPO))]-

Description: While widely used in bioassays, the spectrofluorimetric method described here uses the antenna effect as a tool to probe the thermodynamic parameters of ligands that sensitize lanthanide luminescence. The Eu3+ coordination chemistry, solution thermodynamic stability and photophysical properties of the spermine-based hydroxypyridonate octadentate chelator 3,4,3-LI(1,2-HOPO) are reported. The complex [EuIII(3,4,3-LI(1,2-HOPO))]- luminesces with a long lifetime (805 mu s) and a quantum yield of 7.… more
Date: November 20, 2009
Creator: Abergel, Rebecca J.; D'Aleo, Anthony; Ng Pak Leung, Clara; Shuh, David & Raymond, Kenneth
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Partner: UNT Libraries Government Documents Department
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Aryl Bridged 1-Hydroxypyridin-2-one: Effect of the Bridge on the Eu(III) Sensitization Process

Description: The efficiency of Eu3+ luminescence by energy transfer from an antenna ligand can be strongly dependent on the metal ion coordination geometry. The geometric component of the Eu(III) sensitization has been probed using series of tetradentate 1,2-HOPO derivatives that are connected by bridges of varying length and geometry. The ligands are N,N'-(1,2-phenylene)bis(1-hydroxy-6-oxo-1,6-dihydropyridine-2-carboxamide) for the ligand (L{sup 1}), 1-hydroxy-N-(2-(1-hydroxy-6-oxo-1,6-dihydropyridine-2-ca… more
Date: June 17, 2009
Creator: D'Aleo, Anthony; Moore, Evan G.; Szigethy, Geza; Xu, Jide & Raymond, Kenneth N.
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Partner: UNT Libraries Government Documents Department
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BaBrI:Eu2 + , a new bright scintillator

Description: The scintillation properties of BaBrI:Eu2+ are reported. Crystals were produced by the vertical Bridgman technique in a sealed quartz ampoule. Excellent scintillation properties were measured. A light yield of 81,0007 +- 3000 photons per MeV (ph/MeV) of absorbed gamma-ray energy was measured. An energy resolution (FWHM over peak position) of 4.870.5percent was observed for the 662keV full absorption peak. Pulsed X-ray luminescence measurements show two exponential decay components of 297 and 48… more
Date: November 7, 2009
Creator: Bourret-Courchesne, E.D.; Bizarri, G.; Hanrahan, S.M.; Gundiah, G.; Yan, Z. & Derenzo, S.E.
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Partner: UNT Libraries Government Documents Department
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A [Cyclentetrakis(methylene)]tetrakis[2-hydroxybenzamide]Ligand That Complexes and Sensitizes Lanthanide(III) Ions

Description: The synthesis of a cyclen derivative containing four isophthalamide groups (L{sup 1}) is described. The spectroscopic properties of the Ln(III) complexes of L{sup 1} (Ln = Gd, Tb, Yb, Eu) reveal changes of the UV/visible absorption, circular dichroism absorption, luminescence and circularly polarized luminescence properties. It is shown that at least two metal complex species are present in solution, whose relative amounts are pH dependent. When at pH > 8.0, an intense long lived emission is… more
Date: April 30, 2009
Creator: D'Aleo, Anthony; Xu, Jide; Do, King; Muller, Gilles & Raymond, Kenneth N.
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Partner: UNT Libraries Government Documents Department
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