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Effects of Finite Lattice Heat Capacity on Spin Lattice Relaxation: Theory and Numerical Analysis

Description: Report discussing the transient magnetic behavior of a paramagnetic substance, after an initial disturbance, considered theoretically for a variety of situations in which the lattice temperature rises as a result of energy flow from the magnetic (electron spin) system. Next, the opposite extreme is considered - that in which the resonant and remaining modes are totally uncoupled. Finally, there is a consideration of the case of spins coupled only to the resonant phonons, which in turn are coupl… more
Date: August 1, 1967
Creator: Peterson, Robert L.
Partner: UNT Libraries Government Documents Department
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Changes of the spin dynamics in perovskite and bilayer manganite.

Description: The authors report a series of {micro}SR measurements performed on single crystals of La{sub 1-x}Sr{sub x}MnO{sub 3} (0 {le} x {le} 0.125) and on a polycrystalline bilayer manganite La{sub 2-2x}Sr{sub 1+2x}Mn{sub 2}O{sub 7} (x = 0.52). They find that the temperature dependence of the spin-lattice relaxation rate is strongly dependent on the hole doping and the associated changes in the magnetic structure. The systems have competing, anisotropic interactions, leading to a complex interplay of ch… more
Date: July 2, 2002
Creator: Coldea, A. I.; Blundell, S. J.; Steer, C. A.; Pratt, F. L.; Prabhakaran, D. & Mitchell, J. F.
Partner: UNT Libraries Government Documents Department
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27Al and 1H Solid State NMR Studies Show Evidence of TiAl3 and TiH2 in Ti-doped NaAlH4

Description: Previous X-ray Diffraction (XRD) and Nuclear Magnetic Resonance (NMR) studies on Ti-doped NaAlH{sub 4} revealed the reaction products of two heavily doped (33.3 at.%) samples that were solvent-mixed and mechanically-milled. This investigation revealed that nano-crystalline or amorphous Al{sub 2}O{sub 3} forms from the possible coordination of aluminum with oxygen atom of the furan ring system from added tetrahydrofuran (THF) in the solvent-mixed sample, and that TiAl{sub 3} forms in mechanicall… more
Date: May 26, 2005
Creator: Herberg, J; Maxwell, R & Majzoub, E
Partner: UNT Libraries Government Documents Department
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(129)Xe NMR of Mesoporous Silicas

Description: The porosities of three mesoporous silica materials were characterized with {sup 129}Xe NMR spectroscopy. The materials were synthesized by a sol-gel process with r = 0, 25, and 70% methanol by weight in an aqueous cetyltrimethylammonium bromide solution. Temperature dependent chemical shifts and spin lattice relaxation times reveal that xenon does not penetrate the pores of the largely disordered (r= 70%) silica. For both r = 0 and 25%, temperature dependent resonances corresponding to physiso… more
Date: April 23, 1999
Creator: Anderson, M.T.; Asink, R.A.; Kneller, J.M. & Pietrass, T.
Partner: UNT Libraries Government Documents Department
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Investigation of wettability by NMR microscopy and spin-lattice relaxation

Description: The wettability of reservoir rock has an important impact on the efficiency of oil recovery processes and the distribution of oil and water within the reservoir. One of the potentially useful tools for wettability measurements is nuclear magnetic resonance (NMR) and spin-lattice relaxation. More recently using NMR microscopy NIPER has developed the capability of imaging one- and two-phase fluid systems in reservoir rock at resolutions to 25 microns. Effects seen in the images of fluids within t… more
Date: November 1, 1993
Creator: Doughty, D. A. & Tomutsa, Liviu
Partner: UNT Libraries Government Documents Department
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Application of NMR spectroscopy and multidimensional imaging to the gelcasting process and in-situ real-time monitoring of cross-linking polyacrylamide gels

Description: In the gelcasting process, a slurry of ceramic powder in a solution of organic monomers is cast in a mold. The process is different from injection molding in that it separates mold-filling from setting during conversion of the ceramic slurry to a formed green part. In this work, NMR spectroscopy and imaging have been conducted for in-situ monitoring of the gelation process and for mapping the polymerization. {sup 1}H nuclear magnetic resonance spectra have been obtained during polymerization of… more
Date: April 1, 1995
Creator: Ahuja, S.; Dieckman, S.L. & Gopalsami, N.
Partner: UNT Libraries Government Documents Department
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Characterization of amorphous material in shocked quartz by NMR spectroscopy

Description: Nuclear magnetic resonance (NMR) analysis of the recovered products from a series of controlled explosive shock-loading experiments on quartz powders was performed to investigate shock-induced amorphization processes. Silicon-29 NMR spectroscopy is an excellent probe of the local bonding environment of silicon in minerals and is capable of detecting and characterizing amorphous and disordered components. NMR spectra obtained for the recovered material exhibit a narrow resonance associated with … more
Date: August 1, 1993
Creator: Assink, R. A.; Boslough, M. B. & Cygan, R. T.
Partner: UNT Libraries Government Documents Department
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Unusual relaxation dynamics in La{sub 1-x}Ca{sub x}MnO{sub 3}(X=0.33 and 0.67)

Description: Muon spin relaxation studies on powders of this system show that the dynamic relaxation function changes from exponential above the magnetic transition temperature to stretched exponential below the critical temperature ({Tc}=274 K for x=0.33, T{sub N}=150 K for x=0. 67). This suggests a spatially inhomogeneous distribution of very slow Mn-ion correlation times characteristic of diffusive relaxational dynamics. An anomalously small applied field destroys the dynamical signature of the (ferro)ma… more
Date: July 1996
Creator: Heffner, R. H.; Le, L.; MacLaughlin, D. E.; Luke, G. M.; Kojima, K.; Nachumi, B. et al.
Partner: UNT Libraries Government Documents Department
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Observation of the vortex lattice melting by NMR spin-lattice relaxation in the mixed state

Description: For anisotropic layered superconductors the effect of moving vortices on the nuclear spin magnetization is calculated. Current is supposed to flow along layers, and applied magnetic field is tilted with respect to c-axis. In the solid phase the motion of the vortex lattice produces an alternating magnetic field perpendicular to the applied field which causes the decay of the spin-echo amplitude. This decay rate will display an array of peaks as a function of frequency. In the liquid phase this … more
Date: January 1, 1994
Creator: Bulaevskii, L. N.; Hammel, P. C. & Vinokur, V. M.
Partner: UNT Libraries Government Documents Department
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Magnetic relaxation -- coal swelling, extraction, pore size. Quarterly technical progress report, October 1, 1993--December 31, 1993

Description: During this quarter, the CW (continuous wave) and pulsed EPR (electron paramagnetic resonance) have been examined of the swelled Argonne Premium whole coals and the swelled residues of these coals. The CW EPR spectra will not be of high quality due to the unexpectedly microwave-lossy character of the pyridine used for swelling. Being relatively unaffected by this characteristic, the pulsed EPR measurements of the spin relaxation times of the broad (non-inertinite) and narrow (inertinite) macera… more
Date: December 31, 1993
Creator: Doetschman, D. C.
Partner: UNT Libraries Government Documents Department
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In-situ imaging of charge carriers in an electrochemical cell.

Description: A toroid cavity nuclear magnetic resonance (NMR) detector capable of quantitatively recording radial concentration profiles, diffusion constants, displacements of charge carriers, and radial profiles of spin-lattice relaxation time constants was employed to investigate the charge/discharge cycle of a solid-state electrochemical cell. One-dimensional radial concentration profiles (1D-images) of ions solvated in a polyethylene oxide matrix were recorded by {sup 19}F and {sup 7}Li NMR for several … more
Date: January 30, 1998
Creator: Gerald, R. E., II
Partner: UNT Libraries Government Documents Department
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Linear chain of classical Heisenberg spins with three or four spin interactions

Description: The free energy of a classical Heisenberg chain with three or four spin interactions is shown to equal that of a spin-infinity Ising model. The two-spin Heisenberg correlation function equals a many-spin Ising correlation function and can oscillate with distance.
Date: January 1, 1979
Creator: Barma, M.
Partner: UNT Libraries Government Documents Department
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I: Low Frequency NMR and NQR Using a dc SQUID. II: Variable-temperature 13C CP/MAS of Organometallics

Description: NMR and NQR at low frequencies are difficult prospects due to small nuclear spin polarization. Furthermore, the sensitivity'of the inductive pickup circuitry of standard spectrometers is reduced as the frequency is lowered. I have used a cw-SQUID (Superconducting QUantum Interference Device) spectrometer, which has no such frequency dependence, to study the local atomic environment of {sup 14}N via the quadrupolar interaction. Because {sup 14}N has spin I = 1 and a 0-6 MHz frequency range, it i… more
Date: November 29, 1995
Creator: Ziegeweid, M.A.
Partner: UNT Libraries Government Documents Department
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Development of a functionalized Xenon biosensor

Description: NMR-based biosensors that utilize laser-polarized xenon offer potential advantages beyond current sensing technologies. These advantages include the capacity to simultaneously detect multiple analytes, the applicability to in vivo spectroscopy and imaging, and the possibility of remote amplified detection. Here we present a detailed NMR characterization of the binding of a biotin-derivatized caged-xenon sensor to avidin. Binding of functionalized xenon to avidin leads to a change in the chemica… more
Date: March 25, 2004
Creator: Spence, Megan M.; Ruiz, E. Janette; Rubin, Seth M.; Lowery, Thomas J.; Winssinger, Nicolas; Schultz, Peter G. et al.
Partner: UNT Libraries Government Documents Department
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Characterization of MgO powders for use in thermal batteries

Description: Ten commercial MgO powders were evaluated for their suitability to act as a binder in the separator of thermal batteries to immobilize the electrolyte when it is molten. One brand in particular, Maglite S from Calgon, outperformed all the others. This report describes the results of a characterization study of this MgO as well as similar materials from other commercial vendors. The study objective was to define the critical properties of Maglite S MgO that are responsible for its superior perfo… more
Date: September 1, 1996
Creator: Guidotti, R.A. & Reinhardt, W.
Partner: UNT Libraries Government Documents Department
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Ultrafast optical pump terahertz-probe spectroscopy of strongly correlated electron materials.

Description: We have used optical-pump far-infrared probe spectroscopy to probe the low energy electron dynamics of high temperature superconductors and colossal magnetoresistance manganites. For the superconductor YBa2Cu3O7, picosecond conductivity measurements probe the interplay between Cooper-pairs and quasiparticles. In optimally doped films, the recovery time for long-range phase-coherent pairing increases from {approx}1.5 ps at 4K to {approx}3.5 ps near Tc, consistent with the closing of the supercon… more
Date: January 1, 2001
Creator: Averitt, R. D. (Richard D.); Taylor, Antoinette J.,; Thorsmølle, V. K. (Verner K.); Jia, Quanxi; Lobad, A. I. & Trugman, S. A. (Stuart A.)
Partner: UNT Libraries Government Documents Department
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Fusion with highly spin polarized HD and D{sub 2}. Final report, December 14, 1990--December 13, 1991

Description: This report discusses the following topics relating to inertial confinement with spin polarized hydrogen targets: low temperature implementation of mating a target to omega; dilution-refrigerator cold-entry and retrieval system; target shell tensile strength characterization at low temperatures; and proton and deuteron spin-lattice relaxation measurements in HD in the millikelvin temperature range. (LSP)
Date: June 29, 1992
Creator: Honig, A.
Partner: UNT Libraries Government Documents Department
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Synthesis and Study of Unconventional f-Electron Metals

Description: Research efforts described in this progress report concentrated on the synthesis and exploration of f-electron based materials exhibiting novel properties at low temperatures and on the development of a new experimental technique for low temperatures and high magnetic fields. Specific problems studied included non-Fermi liquid behavior and experimental verifications of novel theories concerned with strong electron correlations. The discovery of non-Fermi liquid behavior has been one of the majo… more
Date: July 25, 2002
Creator: Andraka, Bohdan
Partner: UNT Libraries Government Documents Department
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{sup 9}Be and {sup 11}B NMR study of superconductivity in boron doped UBe{sub 13}

Description: We present {sup 9}Be and {sup 11}B NMR spin-lattice relaxation rate (1/T{sub 1}) measurements in UBe{sub 13-x}B{sub x} for x = 0.03 and 0.07 over the temperature range 0.096 K to 2 K. The temperature dependence of 1/T{sub 1} shows a strong B concentration dependence, especially at low temperatures. We interpret this behavior as consistent with gapless superconductivity induced by the addition of B impurities. The ratio of the {sup 9}Be to {sup 11}B 1/T{sub 1} increases with decreasing temperatu… more
Date: June 9, 1994
Creator: Ahrens, E. T.; Heffner, R. H.; Hammel, P. C.; Reyes, A. P.; Smith, J. L. & Clark, W. G.
Partner: UNT Libraries Government Documents Department
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Nuclear Spin Lattice Relaxation and Conductivity Studies of the Non-Arrhenius Conductivity Behavior in Lithium Fast Ion Conducting Sulfide Glasses

Description: As time progresses, the world is using up more of the planet's natural resources. Without technological advances, the day will eventually arrive when these natural resources will no longer be sufficient to supply all of the energy needs. As a result, society is seeing a push for the development of alternative fuel sources such as wind power, solar power, fuel cells, and etc. These pursuits are even occurring in the state of Iowa with increasing social pressure to incorporate larger percentages … more
Date: May 31, 2003
Creator: Meyer, Benjamin Michael
Partner: UNT Libraries Government Documents Department
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Beam chopper development at LAMPF

Description: In order to reduce pileup limitations on ..mu..SR data rates, a fast chopper for surface muon beams was built and tested at LAMPF. The system allowed one muon at a time to be stopped in a ..mu..SR sample in the following way: A surface beam from the LAMPF Stopped Muon Channel was focused through a crossed-field beam separator and onto a chopper slit. With the separator E and B fields adjusted properly, the beam could pass through the slit. The beam to the ..mu..SR sample was turned on or off (c… more
Date: January 1, 1986
Creator: Hutson, R. L.; Cooke, D. W.; Heffner, R. H.; Schillaci, M. E.; Dodds, S. A. & Gist, G. A.
Partner: UNT Libraries Government Documents Department
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Nuclear magnetic resonance and the question of 5F electron localization in the actinides

Description: Nuclear magnetic resonance results are presented for a number of NaCl-type compounds and cubic Laves-phase type compounds of uranium, neptunium, and plutonium. Special emphasis is placed on the Knight shift and spin-lattice relaxation time measurements and their interpretation in terms of localized or itinerant pictures of the 5Line integral electrons.
Date: January 1, 1976
Creator: Fradin, F. Y.
Partner: UNT Libraries Government Documents Department
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