Sample records for carbon-13 nuclear spin

  1. Protein carbon-13 spin systems by a single two-dimensional nuclear magnetic resonance experiment

    SciTech Connect

    Oh, B.H.; Westler, W.M.; Darba, P.; Markley, J.L.

    1988-05-13

    By applying a two-dimensional double-quantum carbon-13 nuclear magnetic resonance experiment to a protein uniformly enriched to 26% carbon-13, networks of directly bonded carbon atoms were identified by virtue of their one-bond spin-spin couplings and were classified by amino acid type according to their particular single- and double-quantum chemical shift patterns. Spin systems of 75 of the 98 amino acid residues in a protein, oxidized Anabaena 7120 ferredoxin (molecular weight 11,000), were identified by this approach, which represents a key step in an improved methodology for assigning protein nuclear magnetic resonance spectra. Missing spin systems corresponded primarily to residues located adjacent to the paramagnetic iron-sulfur cluster. 25 references, 2 figures.

  2. Robust control of entanglement in a Nitrogen-vacancy centre coupled to a Carbon-13 nuclear spin in diamond

    E-print Network

    R. S. Said; J. Twamley

    2009-03-23

    We address a problem of generating a robust entangling gate between electronic and nuclear spins in the system of a single nitrogen-vacany centre coupled to a nearest Carbon-13 atom in diamond against certain types of systematic errors such as pulse-length and off-resonance errors. We analyse the robustness of various control schemes: sequential pulses, composite pulses and numerically-optimised pulses. We find that numerically-optimised pulses, produced by the gradient ascent pulse engineering algorithm (GRAPE), are more robust than the composite pulses and the sequential pulses. The optimised pulses can also be implemented in a faster time than the composite pulses.

  3. In vivo Carbon-13 Nuclear Magnetic Resonance Studies of Mammals

    NASA Astrophysics Data System (ADS)

    Alger, J. R.; Sillerud, L. O.; Behar, K. L.; Gillies, R. J.; Shulman, R. G.; Gordon, R. E.; Shaw, D.; Hanley, P. E.

    1981-11-01

    Natural abundance carbon-13 nuclear magnetic resonances (NMR) from human arm and rat tissues have been observed in vivo. These signals arise primarily from triglycerides in fatty tissue. Carbon-13 NMR was also used to follow, in a living rat, the conversion of C-1--labeled glucose, which was introduced into the stomach, to C-1--labeled liver glycogen. The carbon-13 sensitivity and resolution obtained shows that natural abundance carbon-13 NMR will be valuable in the study of disorders in fat metabolism, and that experiments with substrates labeled with carbon-13 can be used to study carbohydrate metabolism in vivo.

  4. Characterization of High-Tannin Fractions from Humus by Carbon-13 Cross-Polarization and Magic-Angle Spinning Nuclear Magnetic Resonance

    E-print Network

    Hemminga, Marcus A.

    Characterization of High-Tannin Fractions from Humus by Carbon-13 Cross-Polarization and Magic in Newfoundland with a permanent con- version from forest to heathland (Titus et al., 1995).Condensed tannins can characterized tannin-rich fractions from humus collected in 1998 from et al., 1998). Incubation experiments

  5. Solid-State Carbon-13 Nuclear Magnetic Resonance of Humic Acids at High Magnetic Field Strengths

    E-print Network

    Hemminga, Marcus A.

    commonplace in studies of humic substances in soils and sediments, but when modern high-field spectrometersSolid-State Carbon-13 Nuclear Magnetic Resonance of Humic Acids at High Magnetic Field Strengths were insignificant, and spectral interference due humic acids taken under a variety of conditions. We

  6. Carbon13 nuclear magnetic resonance spectra of keto steroids

    Microsoft Academic Search

    Hanne Eggert; Carl Djerassi

    1973-01-01

    Fourier transform C-13 nuclear magnetic resonance spectra were obtained ; and assigned for a complete series of keto steroids -the steroid skeletons being ; those of androstane and cholestane. The assignments were performed by comparing ; the spectra of these closely related compounds and correlating the shifts due to ; differences in structure, and by use of off-resonance decoupled spectra.

  7. Acceleration of carbon-13 spin-lattice relaxation times in amino acids by electrolytes.

    PubMed

    Tian, Jinping; Yin, Yingwu

    2004-07-01

    Measurements of the enhancement, by various electrolytes, of the spin-lattice relaxation time of carbon-13 at different locations in a number of amino acids are reported. Spin-lattice relaxation times T1 of all the carbons in amino acids generally tend to decrease with increase in the concentration of electrolytes, the largest effects often being observed for the charged carboxylate groups of the amino acids. Carboxylic carbons in amino acids are the sensitive 'acceptor' of the 13C spin-lattice relaxation accelerating effects offered by electrolytes, and the 13C spin-lattice relaxation accelerating ability of electrolytes decreases in the order Mg(ClO4)2 > MgCl2 > CaCl2 > NaCl > KCl > LiClO4 > NaOH. The mechanisms of the observed phenomena are discussed in terms of intermolecular interaction, paramagnetic impurities in electrolytes and other mechanisms; large contributions of intermolecular interactions with electrolytes are present on complex formation between amino acids and metal ions and the incoming 'unsaturation' of the primary solvation shell of cations with the increase in electrolyte concentration. PMID:15181635

  8. Nuclear spin circular dichroism

    SciTech Connect

    Vaara, Juha, E-mail: juha.vaara@iki.fi [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland)] [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, FIN-90014 Oulu (Finland); Rizzo, Antonio [Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa (Italy)] [Istituto per i Processi Chimico-Fisici del Consiglio Nazionale delle Ricerche (IPCF-CNR), Area della Ricerca, via G. Moruzzi 1, I-56124 Pisa (Italy); Kauczor, Joanna; Norman, Patrick [Department of Physics, Chemistry and Biology, Linköping University, S-58183 Linköping (Sweden)] [Department of Physics, Chemistry and Biology, Linköping University, S-58183 Linköping (Sweden); Coriani, Sonia, E-mail: coriani@units.it [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy)] [Dipartimento di Scienze Chimiche e Farmaceutiche, Università degli Studi di Trieste, Via L. Giorgieri 1, I-34127 Trieste (Italy)

    2014-04-07

    Recent years have witnessed a growing interest in magneto-optic spectroscopy techniques that use nuclear magnetization as the source of the magnetic field. Here we present a formulation of magnetic circular dichroism (CD) due to magnetically polarized nuclei, nuclear spin-induced CD (NSCD), in molecules. The NSCD ellipticity and nuclear spin-induced optical rotation (NSOR) angle correspond to the real and imaginary parts, respectively, of (complex) quadratic response functions involving the dynamic second-order interaction of the electron system with the linearly polarized light beam, as well as the static magnetic hyperfine interaction. Using the complex polarization propagator framework, NSCD and NSOR signals are obtained at frequencies in the vicinity of optical excitations. Hartree-Fock and density-functional theory calculations on relatively small model systems, ethene, benzene, and 1,4-benzoquinone, demonstrate the feasibility of the method for obtaining relatively strong nuclear spin-induced ellipticity and optical rotation signals. Comparison of the proton and carbon-13 signals of ethanol reveals that these resonant phenomena facilitate chemical resolution between non-equivalent nuclei in magneto-optic spectra.

  9. SUBSTITUENT EFFECTS AND ADDITIVITY IN THE CARBON-13 NUCLEAR MAGNETIC RESONANCE SPECTRA OF CHLORINATED NAPHTHALENES AND THEIR CHLORINATED NAPHTHOL METABOLITES

    EPA Science Inventory

    Carbon-13 and proton nuclear magnetic resonance spectra were obtained for 12 chlorinated naphthalenes and six chlorinated naphthols, some of which are metabolites of the naphthalenes. The validity of the use of additivity of chlorine and hydroxyl substituent effects to predict 13...

  10. Characterization of the International Humic Substances Society standard and reference fulvic and humic acids by solution state carbon-13 (13C) and hydrogen-1 (1H) nuclear magnetic resonance spectrometry

    USGS Publications Warehouse

    Thorn, Kevin A.; Folan, Daniel W.; MacCarthy, Patrick

    1989-01-01

    Standard and reference samples of the International Humic Substances Society have been characterized by solution state carbon-13 and hydrogen-1 nuclear magnetic resonance (NMR) spectrometry. Samples included the Suwannee River, soil, and peat standard fulvic and humic acids, the Leonardite standard humic acid, the Nordic aquatic reference fulvic and humic acids, and the Summit Hill soil reference humic acid. Aqueous-solution carbon-13 NMR analyses included the measurement of spin-lattice relaxation times, measurement of nuclear Overhauser enhancement factors, measurement of quantitative carbon distributions, recording of attached proton test spectra, and recording of spectra under nonquantitative conditions. Distortionless enhancement by polarization transfer carbon-13 NMR spectra also were recorded on the Suwannee River fulvic acid in deuterated dimethyl sulfoxide. Hydrogen-1 NMR spectra were recorded on sodium salts of the samples in deuterium oxide. The carbon aromaticities of the samples ranged from 0.24 for the Suwannee River fulvic acid to 0.58 for the Leonardite humic acid.

  11. Coherent manipulation of an NV center and one carbon nuclear spin

    NASA Astrophysics Data System (ADS)

    Scharfenberger, Burkhard; Munro, William J.; Nemoto, Kae

    2014-12-01

    We study a three-qubit system formed by the NV center's electronic and nuclear spin plus an adjacent spin 1/2 carbon 13C . Specifically, we propose a manipulation scheme utilizing the hyperfine coupling of the effective S=1 degree of freedom of the vacancy electrons to the two adjacent nuclear spins to achieve accurate coherent control of all three qubits.

  12. Carbon-13 nuclear magnetic resonance studies of cobalt transferrin and selected model compounds

    E-print Network

    Philen, Rossanne McElroy

    1975-01-01

    + 13 2- Preparation of Co -transferrin- CO . . 32 3 Carbon-13 nmr Data Collection. 3+ ~ . 13 2- Co -transferrin- CO 3 35 35 Model Compounds. 35 pH Studies of [Co(NH ) CO ]NO and 13 [Co(NH ) CO ]NO . . . . . . . . . . . . . . . . . . . 36 13... NMR Spectrometer Settings. . CHAPTER IV. RESULTS. Data. 36 37 37 Conclusions 60 REFERENCES 74 VITA 79 Figure 1, LIST OF FIGURES 3+ Geometry of Fe -transferrin-HCO binding site proposed by Wishnia (33). . . . . . . . . . . . . . 3 Figure 2...

  13. Natural abundance carbon-13 nuclear magnetic resonance studies of bovine white matter and myelin.

    PubMed

    Williams, E C; Cordes, E H

    1976-12-28

    Whole bovine white matter yields a poorly resolved natural abundance 13C nuclear magnetic resonance (NMR) spectrum. The spectrum principally reflects carbon atoms of the constituent membrane lipids: several resonances could be specifically assigned but no resonances attributable to cholesterol are detectable. Except for the methyl group at the terminus of fatty acyl chains, lipid carbons giving rise to the 13C NMR spectrum have values of spin-lattice relaxation time between 140 and 500 ms, indicating significant restrictions on segmental and rotational mibolities but consistent with a generally fluid structural organization. The 13C NMR spectrum of myelin isolated from bovine white matter is similar to that for the whole white matter itself. In both white matter and isolated meylin, the integrated intensities for several carbon atoms are considerably less than those for the same carbon atoms in total lipid extracts. The data for white matter and myelin are consistent with a model in which observed line broadening is due to restrictions in the amplitude of chain flexing rather than to severe restrictions on chain segmental motion. Failure to detect resonances of cholesterol ring system carbon atoms may reflect marked anisotropy of rotational reorientation. PMID:1009087

  14. A carbon-13 and proton nuclear magnetic resonance study of some experimental referee broadened-specification /ERBS/ turbine fuels

    NASA Technical Reports Server (NTRS)

    Dalling, D. K.; Pugmire, R. J.

    1982-01-01

    Preliminary results of a nuclear magnetic resonance (NMR) spectroscopy study of alternative jet fuels are presented. A referee broadened-specification (ERBS) aviation turbine fuel, a mixture of 65 percent traditional kerosene with 35 percent hydrotreated catalytic gas oil (HCGO) containing 12.8 percent hydrogen, and fuels of lower hydrogen content created by blending the latter with a mixture of HCGO and xylene bottoms were studied. The various samples were examined by carbon-13 and proton NMR at high field strength, and the resulting spectra are shown. In the proton spectrum of the 12.8 percent hydrogen fuel, no prominent single species is seen while for the blending stock, many individual lines are apparent. The ERBS fuels were fractionated by high-performance liquid chromatography and the resulting fractions analyzed by NMR. The species found are identified.

  15. Determination of alkylbenzenesulfonate surfactants in groundwater using macroreticular resins and carbon-13 nuclear magnetic resonance spectrometry

    SciTech Connect

    Thurman, E.M.; Willoughby, T.; Barber, L.B. Jr.; Thorn, K.A.

    1987-07-15

    Alkylbenzenesulfonate surfactants were determined in groundwater at concentrations as low as 0.3 mg/L. The method uses XAD-8 resin for concentration, followed by elution with methanol, separation of anionic and nonionic surfactants by anion exchange, quantitation by titration, and identification by TC nuclear magnetic resonance spectrometry. Laboratory standards and field samples containing straight-chain and branched-chain alkylbenzenesulfonates, sodium dodecyl sulfate, and alkylbenzene ethoxylates were studied. The XAD-8 extraction of surfactants from groundwater was completed in the field, which simplified sample preservation and reduced the cost of transporting samples.

  16. Nonheuristic Computer Determination of Molecular Structure Based Upon Carbon-13 Nuclear Magnetic Resonance Data. Branched Alkanes

    PubMed Central

    Burlingame, A. L.; Mcpherron, R. V.; Wilson, D. M.

    1973-01-01

    A computer-based system for elucidation of molecular structure is described for the branched alkanes, based upon 13C nuclear magnetic resonance data. All possible structures of a given carbon content are exhaustively generated in a DENDRAL-like manner, and scored according to the fit of their predicted spectral characteristics to those of the “unknown” alkane. The technique may be generalized to any class of organic compounds for which 13C chemical-shift additivity parameters are reliable, and shows promise for stereochemical elucidation. PMID:4519635

  17. Determination of alkylbenzenesulfonate surfactants in groundwater using macroreticular resins and carbon-13 nuclear magnetic resonance spectrometry

    USGS Publications Warehouse

    Thurman, E.M.; Willoughby, T.; Barber, L.B., Jr.; Thorn, K.A.

    1987-01-01

    Alkylbenzenesulfonate surfactants were determined in groundwater at concentrations as low as 0.3 mg/L. The method uses XAD-8 resin for concentration, followed by elution with methanol, separation of anionic and nonionic surfactants by anion exchange, quantitation by titration, and identification by 13C nuclear magnetic resonance spectrometry. Laboratory standards and field samples containing straight-chain and branched-chain alkylbenzenesulfonates, sodium dodecyl sulfate, and alkylbenzene ethoxylates were studied. The XAD-8 extraction of surfactants from groundwater was completed in the field, which simplified sample preservation and reduced the cost of transporting samples.

  18. Carbon-13 nuclear magnetic resonance spectroscopy of lipids: Differential line broadening due to cross-correlation effects as a probe of membrane structure

    SciTech Connect

    Oldfield, E.; Adebodun, F.; Chung, J.; Montez, B.; Ki Deok Park; Hongbiao Le; Phillips, B. (Univ. of Illinois, Urbana (United States))

    1991-11-19

    The authors have obtained proton-coupled carbon-13 nuclear magnetic resonance (NMR) spectra of a variety of lipid-water and lipid-drug-water systems, at 11.7 T, as a function of temperature, using the 'magic-angle' sample-spinning (MAS) NMR technique. The resulting spectra show a wide range of line shapes, due to interferences between dipole-dipole and dipole-chemical shielding anisotropy interactions. The differential line-broadening effects observed are particularly large for aromatic and olefinic (sp{sup 2}) carbon atom sites. Coupled spectra of the tricyclic antidepressants desipramine and imipramine, in 1,2-dimyristoyl-sn-glycero-3-phosphocholine-water mesophases, show well-resolved doublets having different line shapes for each of the four aromatic methine groups, due to selective averaging of the four C-H dipolar interactions due to rapid motion about the director (or drug C{sub 2}) axis. {sup 2}H NMR spectra of (2,4,6,8-{sup 2}H{sub 4})desipramine (and imipramine) in the same 1,2-dimyristoyl-sn-glycero-3-phosphocholine-water mesophase exhibit quadrupole splittings of {approximately}0-2 and {approximately}20 kHz, indicating an approximate magic-angle orientation of the C2-{sup 2}H({sup 1}H) and C8-{sup 2}H({sup 1}H) vectors with respect to an axis of motional averaging, in accord with the {sup 13}C NMR results. The good qualitative agreement between {sup 13}C and {sup 2}H NMR results suggests that useful orientational ({sup 2}H NMR like) information can be deduced from natural-abundance {sup 13}C NMR spectra of a variety of mobile solids.

  19. Application of solid state silicone-29 and carbon-13 nuclear magnetic resonance spectroscopy to the characterization of inorganic matter-humic complexes in Athabasca oil sands

    SciTech Connect

    Kotlyar, L.S.; Ripmeester, J.A.

    1988-06-01

    The ease of bitumen recovery from oil sand by hot or cold water separation techniques depends upon the surface properties of the components, especially water wet character of the clay and sand particles. Oil wetting of some of the oils and sand solids is believed to be caused by the presence of humic matter-non-crystalline inorganic complexes. Characterization of these complexes using solid state carbon-13 and silicon-29 magic spinning angle (MAS) NMR spectroscopy was the purpose of the present work.

  20. Carbon-13 and proton nuclear magnetic resonance analysis of shale-derived refinery products and jet fuels and of experimental referee broadened-specification jet fuels

    NASA Technical Reports Server (NTRS)

    Dalling, D. K.; Bailey, B. K.; Pugmire, R. J.

    1984-01-01

    A proton and carbon-13 nuclear magnetic resonance (NMR) study was conducted of Ashland shale oil refinery products, experimental referee broadened-specification jet fuels, and of related isoprenoid model compounds. Supercritical fluid chromatography techniques using carbon dioxide were developed on a preparative scale, so that samples could be quantitatively separated into saturates and aromatic fractions for study by NMR. An optimized average parameter treatment was developed, and the NMR results were analyzed in terms of the resulting average parameters; formulation of model mixtures was demonstrated. Application of novel spectroscopic techniques to fuel samples was investigated.

  1. Lactoperoxidase-catalyzed oxidation of thiocyanate ion: a carbon-13 nuclear magnetic resonance study of the oxidation products.

    PubMed

    Pollock, J R; Goff, H M

    1992-10-20

    Products formed from the lactoperoxidase (LPO) catalyzed oxidation of thiocyanate ion (SCN-) with hydrogen peroxide (H2O2) have been studied by 13C-NMR at pH 6 and pH 7. Ultimate formation of hypothiocyanite ion (OSCN-) as the major product correlates well with the known optical studies. The oxidation rate of SCN- appears to be greater at pH < or = 6.0. At [H2O2]/[SCN-] ratios of < or = 0.5, OSCN- is not formed immediately, but an unidentified intermediate is produced. At [H2O2]/[SCN-] > 0.5, SCN- appears to be directly oxidized to OSCN-. Once formed, OSCN- slowly degrades over a period of days to carbon dioxide (CO2), bicarbonate ion (HCO3-), and hydrogen cyanide (HCN). An additional, previously unrecognized product also appears after formation of OSCN-. On the basis of carbon-13 chemical shift information this new species is suggested to result from rearrangement of OSCN- to yield the thiooxime isomer, SCNO- or SCNOH. PMID:1390933

  2. High-spin nuclear spectroscopy

    SciTech Connect

    Diamond, R.M.

    1986-07-01

    High-spin spectroscopy is the study of the changes in nuclear structure, properties, and behavior with increasing angular momentum. It involves the complex interplay between collective and single-particle motion, between shape and deformation changes, particle alignments, and changes in the pairing correlations. A review of progress in theory, experimentation, and instrumentation in this field is given. (DWL)

  3. Electron spin decoherence in nuclear spin baths and dynamical decoupling

    SciTech Connect

    Zhao, N.; Yang, W.; Ho, S. W.; Hu, J. L.; Wan, J. T. K.; Liu, R. B. [Department of Physics, Chinese University of Hong Kong, Shatin, New Territories (Hong Kong)

    2011-12-23

    We introduce the quantum theory of the electron spin decoherence in a nuclear spin bath and the dynamical decoupling approach for protecting the electron spin coherence. These theories are applied to various solid-state systems, such as radical spins in molecular crystals and NV centers in diamond.

  4. Submillisecond Hyperpolarization of Nuclear Spins in Silicon

    NASA Astrophysics Data System (ADS)

    Hoehne, Felix; Dreher, Lukas; Franke, David P.; Stutzmann, Martin; Vlasenko, Leonid S.; Itoh, Kohei M.; Brandt, Martin S.

    2015-03-01

    In this Letter, we devise a fast and effective nuclear spin hyperpolarization scheme, which is, in principle, magnetic field independent. We use this scheme to experimentally demonstrate polarizations of up to 66% for phosphorus donor nuclear spins in bulk silicon, which are created within less than 100 ? s in a magnetic field of 0.35 T at a temperature of 5 K. The polarization scheme is based on a spin-dependent recombination process via weakly coupled spin pairs, for which the recombination time constant strongly depends on the relative orientation of the two spins. We further use this scheme to measure the nuclear spin relaxation time and find a value of ˜100 ms under illumination, in good agreement with the value calculated for nuclear spin flips induced by repeated ionization and deionization processes.

  5. Submillisecond hyperpolarization of nuclear spins in silicon.

    PubMed

    Hoehne, Felix; Dreher, Lukas; Franke, David P; Stutzmann, Martin; Vlasenko, Leonid S; Itoh, Kohei M; Brandt, Martin S

    2015-03-20

    In this Letter, we devise a fast and effective nuclear spin hyperpolarization scheme, which is, in principle, magnetic field independent. We use this scheme to experimentally demonstrate polarizations of up to 66% for phosphorus donor nuclear spins in bulk silicon, which are created within less than 100???s in a magnetic field of 0.35 T at a temperature of 5 K. The polarization scheme is based on a spin-dependent recombination process via weakly coupled spin pairs, for which the recombination time constant strongly depends on the relative orientation of the two spins. We further use this scheme to measure the nuclear spin relaxation time and find a value of ?100??ms under illumination, in good agreement with the value calculated for nuclear spin flips induced by repeated ionization and deionization processes. PMID:25839308

  6. Constituents of the leaves of Woodfordia fruticosa Kurz. I. Isolation, structure, and proton and carbon-13 nuclear magnetic resonance signal assignments of woodfruticosin (woodfordin C), an inhibitor of deoxyribonucleic acid topoisomerase II.

    PubMed

    Kadota, S; Takamori, Y; Nyein, K N; Kikuchi, T; Tanaka, K; Ekimoto, H

    1990-10-01

    Woodfruticosin (woodfordin C), a new cyclic dimeric hydrolyzable tannin having an inhibitory activity toward deoxyribonucleic acid (DNA) topoisomerase II, has been isolated from the leaves of Woodfordia fruticosa Kurz (Lythraceae) along with three known flavonol glycosides and three known flavonol glycoside gallates. The structure of wood fruticosin (woodfordin C) was determined by the use of two-dimensional nuclear magnetic resonance (2-D NMR) spectroscopy including heteronuclear multiple quantum coherence (HMQC) and heteronuclear multiple bond connectivity (HMBC) techniques. Detailed analyses of the proton and carbon-13 NMR (1H- and 13C-NMR) spectra of six known flavonoids were performed. PMID:1963810

  7. Liquid-state nuclear spin comagnetometers

    NASA Astrophysics Data System (ADS)

    Ledbetter, Micah; Pustelny, Szymon; Budker, Dmitry; Romalis, Michael; Blanchard, John; Pines, Alexander

    2012-06-01

    We discuss liquid-state nuclear spin comagnetometers based on mixtures of mutually miscible solvents, each rich in a different nuclear spin. In one version thereof, thermally polarized ^1H and ^19F nuclear spins in a mixture of pentane and hexafluorobenzene are monitored in 1 mG fields using alkali-vapor magnetometers. In a second version, ^1H and ^129Xe spins in a mixture of pentane and hyperpolarized liquid xenon are monitored with a superconducting quantum interference device. In the former case, we show that magnetic field fluctuations can be suppressed by a factor of about 3400 and that frequency resolution of about 5x10-11 Hz may be realized in roughly one day of integration. We discuss the application of liquid-state nuclear spin comagnetometers to precision measurements such as a search for spin-gravity coupling or a permanent electric dipole moment, as well as to sensitive gyroscopes.

  8. The NV center as a quantum actuator: time-optimal control of nuclear spins

    E-print Network

    Clarice D. Aiello; Paola Cappellaro

    2014-10-21

    Indirect control of qubits by a quantum actuator has been proposed as an appealing strategy to manipulate qubits that couple only weakly to external fields. While universal quantum control can be easily achieved when the actuator-qubit coupling is anisotropic, the efficiency of this approach is less clear. Here we analyze the time-efficiency of the quantum actuator control. We describe a strategy to find time-optimal control sequence by the quantum actuator and compare their gate times with direct driving, identifying regimes where the actuator control performs faster. As an example, we focus on a specific implementation based on the Nitrogen-Vacancy center electronic spin in diamond (the actuator) and nearby carbon-13 nuclear spins (the qubits).

  9. Nuclear spin conversion in diatomic molecules

    SciTech Connect

    Il'ichev, L. V., E-mail: leonid@iae.nsk.su; Shalagin, A. M. [Russian Academy of Sciences, Institute of Automation and Electrometry, Siberian Branch (Russian Federation)] [Russian Academy of Sciences, Institute of Automation and Electrometry, Siberian Branch (Russian Federation)

    2013-07-15

    A mechanism of the internal interaction in dimers that mixes different nuclear spin modifications has been proposed. It has been shown that the intramolecular current associated with transitions between electronic terms of different parities can generate different magnetic fields on nuclei, leading to transitions between spin modifications and to the corresponding changes in rotational states. In the framework of the known quantum relaxation process, this interaction initiates irreversible conversion of nuclear spin modifications. The estimated conversion rate for nitrogen at atmospheric pressure is quite high (10{sup -3}-10{sup -5} s{sup -1})

  10. Spin excitations in di-nuclear systems

    SciTech Connect

    Back, B.B.

    1990-01-01

    The spin excitations of products from two-body reactions have two sources: transfer of orbital motion into intrinsic spins via tangential friction and thermal excitations of di-nuclear spin modes. The relative importance of these two mechanisms is discussed for deep inelastic scattering, quasi-fission and spontaneous fission processes. The results of simple model calculations are compared to measured {gamma}-multiplicities in {sup 238}U induced quasi-fission reactions and it is concluded that the spin-excitation are only partially equilibrated during the interaction. 11 refs., 5 figs.

  11. Liquid-State Nuclear Spin Comagnetometers

    NASA Astrophysics Data System (ADS)

    Ledbetter, M. P.; Pustelny, S.; Budker, D.; Romalis, M. V.; Blanchard, J. W.; Pines, A.

    2012-06-01

    We discuss nuclear spin comagnetometers based on ultralow-field nuclear magnetic resonance in mixtures of miscible solvents, each rich in a different nuclear spin. In one version thereof, Larmor precession of protons and F19 nuclei in a mixture of thermally polarized pentane and hexafluorobenzene is monitored via a sensitive alkali-vapor magnetometer. We realize transverse relaxation times in excess of 20 s and suppression of magnetic field fluctuations by a factor of 3400. We estimate it should be possible to achieve single-shot sensitivity of about 5×10-9Hz, or about 5×10-11Hz in ?1 day of integration. In a second version, spin precession of protons and Xe129 nuclei in a mixture of pentane and hyperpolarized liquid xenon is monitored using superconducting quantum interference devices. Application to spin-gravity experiments, electric dipole moment experiments, and sensitive gyroscopes is discussed.

  12. The spin-temperature theory of dynamic nuclear polarization and nuclear spin-lattice relaxation

    NASA Technical Reports Server (NTRS)

    Byvik, C. E.; Wollan, D. S.

    1974-01-01

    A detailed derivation of the equations governing dynamic nuclear polarization (DNP) and nuclear spin lattice relaxation by use of the spin temperature theory has been carried to second order in a perturbation expansion of the density matrix. Nuclear spin diffusion in the rapid diffusion limit and the effects of the coupling of the electron dipole-dipole reservoir (EDDR) with the nuclear spins are incorporated. The complete expression for the dynamic nuclear polarization has been derived and then examined in detail for the limit of well resolved solid effect transitions. Exactly at the solid effect transition peaks, the conventional solid-effect DNP results are obtained, but with EDDR effects on the nuclear relaxation and DNP leakage factor included. Explicit EDDR contributions to DNP are discussed, and a new DNP effect is predicted.

  13. The physical state of osmoregulatory solutes in unicellular algae. A natural-abundance carbon-13 nuclear-magnetic-resonance relaxation study.

    PubMed Central

    Norton, R S; MacKay, M A; Borowitzka, L J

    1982-01-01

    Natural-abundance 13C n.m.r. spin-lattice relaxation-time measurements have been carried out on intact cells of the unicellular blue--green alga Synechococcus sp. and the unicellular green alga Dunaliella salina, with the aim of characterizing the environments of the organic osmoregulatory solutes in these salt-tolerant organisms. In Synechococcus sp., all of the major organic osmoregulatory solute, 2-O-alpha-D-glucopyranosylglycerol, is visible in spectra of intact cells. Its rotational motion in the cell is slower by a factor of approx. 2.4 than in aqueous solution, but the molecule is still freely mobile and therefore able to contribute to the osmotic balance. In D. salina, only about 60% of the osmoregulatory solute glycerol is visible in spectra of intact cells. The rotational mobility of this observable fraction is approximately half that found in aqueous solution, but the data also indicate that there is a significant concentration of some paramagnetic species in D. salina which contributes to the overall spin-lattice relaxation of the glycerol carbon atoms. The non-observable fraction, which must correspond to glycerol molecules that have very broad 13C resonances and that are in slow exchange with bulk glycerol, has not been properly characterized as yet, but may represent glycerol in the chloroplast. The implications of these findings in relation to the physical state of the cytoplasm and the mechanism of osmoregulation in these cells are discussed. PMID:6807296

  14. Optical switching of nuclear spin-spin couplings in semiconductors.

    PubMed

    Goto, Atsushi; Ohki, Shinobu; Hashi, Kenjiro; Shimizu, Tadashi

    2011-01-01

    Two-qubit operation is an essential part of quantum computation. However, solid-state nuclear magnetic resonance quantum computing has not been able to fully implement this functionality, because it requires a switchable inter-qubit coupling that controls the time evolutions of entanglements. Nuclear dipolar coupling is beneficial in that it is present whenever nuclear-spin qubits are close to each other, while it complicates two-qubit operation because the qubits must remain decoupled to prevent unwanted couplings. Here we introduce optically controllable internuclear coupling in semiconductors. The coupling strength can be adjusted externally through light power and even allows on/off switching. This feature provides a simple way of switching inter-qubit couplings in semiconductor-based quantum computers. In addition, its long reach compared with nuclear dipolar couplings allows a variety of options for arranging qubits, as they need not be next to each other to secure couplings. PMID:21730962

  15. Optical switching of nuclear spin–spin couplings in semiconductors

    PubMed Central

    Goto, Atsushi; Ohki, Shinobu; Hashi, Kenjiro; Shimizu, Tadashi

    2011-01-01

    Two-qubit operation is an essential part of quantum computation. However, solid-state nuclear magnetic resonance quantum computing has not been able to fully implement this functionality, because it requires a switchable inter-qubit coupling that controls the time evolutions of entanglements. Nuclear dipolar coupling is beneficial in that it is present whenever nuclear–spin qubits are close to each other, while it complicates two-qubit operation because the qubits must remain decoupled to prevent unwanted couplings. Here we introduce optically controllable internuclear coupling in semiconductors. The coupling strength can be adjusted externally through light power and even allows on/off switching. This feature provides a simple way of switching inter-qubit couplings in semiconductor-based quantum computers. In addition, its long reach compared with nuclear dipolar couplings allows a variety of options for arranging qubits, as they need not be next to each other to secure couplings. PMID:21730962

  16. Nuclear spin effects in optical lattice clocks

    SciTech Connect

    Boyd, Martin M.; Zelevinsky, Tanya; Ludlow, Andrew D.; Blatt, Sebastian; Zanon-Willette, Thomas; Foreman, Seth M.; Ye Jun [JILA, National Institute of Standards and Technology and University of Colorado, Department of Physics, University of Colorado, Boulder, Colorado 80309-0440 (United States)

    2007-08-15

    We present a detailed experimental and theoretical study of the effect of nuclear spin on the performance of optical lattice clocks. With a state-mixing theory including spin-orbit and hyperfine interactions, we describe the origin of the {sup 1}S{sub 0}-{sup 3}P{sub 0} clock transition and the differential g factor between the two clock states for alkaline-earth-metal(-like) atoms, using {sup 87}Sr as an example. Clock frequency shifts due to magnetic and optical fields are discussed with an emphasis on those relating to nuclear structure. An experimental determination of the differential g factor in {sup 87}Sr is performed and is in good agreement with theory. The magnitude of the tensor light shift on the clock states is also explored experimentally. State specific measurements with controlled nuclear spin polarization are discussed as a method to reduce the nuclear spin-related systematic effects to below 10{sup -17} in lattice clocks.

  17. Assignments in the Carbon-13 Nuclear Magnetic Resonance Spectra of Vitamin B12, Coenzyme B12, and Other Corrinoids: Application of Partially-Relaxed Fourier Transform Spectroscopy

    PubMed Central

    Doddrell, David; Allerhand, Adam

    1971-01-01

    High-resolution Fourier transform NMR at 15.08 MHz was used to observe the proton-decoupled natural-abundance 13C spectra of aqueous solutions of cobinamide dicyanide (0.067 M), cyanocobalamin (0.024 M), dicyanocobalamin (0.14 M), and coenzyme B12 (0.038 M). Assignments were made with the aid of chemical shift comparisons, off-resonance single-frequency proton decoupling, partially-relaxed Fourier transform spectra, and splittings arising from 13C-31P coupling. As expected, the 13C spectra of the coronoids were appreciably more informative than the corresponding proton spectra. Nearly all the lines in the 13C spectra of the corrinoids were well-resolved single-carbon resonances, in spite of the structural complexity. Partially relaxed 13C Fourier transform NMR spectra, which yield spin-lattice relaxation times of each resolved resonance, were found to be a very useful addition to the arsenal of NMR techniques. PMID:5280523

  18. Nuclear spin physics in quantum dots: An optical investigation

    NASA Astrophysics Data System (ADS)

    Urbaszek, Bernhard; Marie, Xavier; Amand, Thierry; Krebs, Olivier; Voisin, Paul; Maletinsky, Patrick; Högele, Alexander; Imamoglu, Atac

    2013-01-01

    The mesoscopic spin system formed by the 104-106 nuclear spins in a semiconductor quantum dot offers a unique setting for the study of many-body spin physics in the condensed matter. The dynamics of this system and its coupling to electron spins is fundamentally different from its bulk counterpart or the case of individual atoms due to increased fluctuations that result from reduced dimensions. In recent years, the interest in studying quantum-dot nuclear spin systems and their coupling to confined electron spins has been further fueled by its importance for possible quantum information processing applications. The fascinating nonlinear (quantum) dynamics of the coupled electron-nuclear spin system is universal in quantum dot optics and transport. In this article, experimental work performed over the last decade in studying this mesoscopic, coupled electron-nuclear spin system is reviewed. Here a special focus is on how optical addressing of electron spins can be exploited to manipulate and read out the quantum-dot nuclei. Particularly exciting recent developments in applying optical techniques to efficiently establish nonzero mean nuclear spin polarizations and using them to reduce intrinsic nuclear spin fluctuations are discussed. Both results critically influence the preservation of electron-spin coherence in quantum dots. This overall recently gained understanding of the quantum-dot nuclear spin system could enable exciting new research avenues such as experimental observations of spontaneous spin ordering or nonclassical behavior of the nuclear spin bath.

  19. Spectral assignment by carbon-13 autocorrelation spectroscopy

    NASA Astrophysics Data System (ADS)

    Turner, David L.

    A variety of techniques for generating two-dimensional autocorrelation spectra of coupled carbon-13 nuclei have been compared theoretically, and the optimization of the method is described with reference to the macrolide antibiotic tylactone.

  20. NUCLEAR SPIN ISOSPIN RESPONSES FOR LOW-ENERGY NEUTRINOS

    E-print Network

    Washington at Seattle, University of

    NUCLEAR SPIN ISOSPIN RESPONSES FOR LOW-ENERGY NEUTRINOS Hiroyasu EJIRI Nuclear Physics Laboratory@rcnp.osaka-u.ac.jp (H. Ejiri). Physics Reports 338 (2000) 265}351 Nuclear spin isospin responses for low-energy Research Center for Nuclear Physics, Osaka University, Ibaraki, Osaka, 567 Japan. E-mail address: ejiri

  1. Spin responses in correlated nuclear matter

    NASA Astrophysics Data System (ADS)

    Fabrocini, Adelchi

    1994-02-01

    Correlated Basis Function theory is used to compute the longitudinal and transverse dynamical spin responses in nuclear matter. The effect of the tensor correlations, induced by realistic nucleon-nucleon interactions, is studied in the isoscalar and isovector channels. Their inclusion brings the values of the ratio between the longitudinal and transverse responses close to unity and to the experimental estimates in medium-heavy nuclei.

  2. Locking electron spins into resonance by electron-nuclear feedback

    NASA Astrophysics Data System (ADS)

    Nowack, Katja

    2009-03-01

    All basic building blocks for spin-based quantum information processing using electron spins in GaAs quantum dots have recently been realized. Recent experiments have shown single-shot read-out of an individual spin [1], the implementation of the SWAP gate [2] and (magnetically induced) coherent single electron spin rotations [3]. However, the main drawback of using electron spins in a GaAs environment is the short spin coherence time, which is measured to be in the nanosecond range [2,4]. The source of this fast decoherence is the hyperfine interaction of the localized electron spin with the randomly fluctuating nuclear spins of the host lattice. The fluctuations of the nuclear spins have to be reduced to extend the electron spin coherence time. We therefore study the electron-nuclear spin interaction and use magnetically driven spin resonance to control the electron spin and indirectly manipulate the nuclear spins. We apply continuous microwave excitation to the electron spin and observe strong electron-nuclear feedback. One experimental signature of this feedback is the locking of the electron spin system into resonance with the microwaves. Once the electron spin is locked into resonance, this resonance condition remains fullfilled even when the external magnetic field or the microwave frequency is changed. This is due to dynamically build up nuclear polarizations (up to 500 mT) which generally counteract the external magnetic field. Locking of the electron spin system into resonance might indicate that the nuclear polarization exhibits stable configurations where fluctuations of the nuclear distribution are reduced [5]. [4pt] References [0pt] [1] J. M. Elzerman et al. , Nature 430, 431 (2004) [0pt] [2]. J. R. Petta et al., Science 309, 2180 (2005). [0pt] [3] F. H. L. Koppens et al., Nature 442, 766 (2006). [0pt] [4] F. H. L. Koppens et al., Phys. Rev. Lett. 100, 236802 (2008). [0pt] [5] J. Danon and Yu. V. Nazarov, private communication.

  3. The production of lipids alternately labelled with carbon-13.

    PubMed

    Boyle-Roden, Elizabeth; German, J B; Wood, B J B

    2003-07-01

    Chlorella cells were shown to have similar fatty acid profiles when grown photoautotrophically or if grown photoheterotrophically with ethanoate (acetate) as carbon source. When supplied with ethanoate labelled with carbon-13 in the methyl group, the alga incorporated it into fatty acids with retention of the sequence of labelling on alternate carbon atoms, thus providing a convenient method for synthesising lipids in a form useful for nuclear magnetic resonance (NMR) studies of lipids in situ in membranes. Marine algae used in fish farming may have higher levels of very highly unsaturated fatty acids; proposals for producing these compounds labelled with carbon-13 are, therefore, presented, based on using centrally labelled glycerol. The scope for producing other substances labelled in a form suitable for NMR studies, such as carotenoids, is discussed. PMID:12919810

  4. Coherent Control of a Single 29Si Nuclear Spin Qubit

    NASA Astrophysics Data System (ADS)

    Pla, Jarryd J.; Mohiyaddin, Fahd A.; Tan, Kuan Y.; Dehollain, Juan P.; Rahman, Rajib; Klimeck, Gerhard; Jamieson, David N.; Dzurak, Andrew S.; Morello, Andrea

    2014-12-01

    Magnetic fluctuations caused by the nuclear spins of a host crystal are often the leading source of decoherence for many types of solid-state spin qubit. In group-IV semiconductor materials, the spin-bearing nuclei are sufficiently rare that it is possible to identify and control individual host nuclear spins. This Letter presents the first experimental detection and manipulation of a single 29Si nuclear spin. The quantum nondemolition single-shot readout of the spin is demonstrated, and a Hahn echo measurement reveals a coherence time of T2=6.3 (7 ) ms —in excellent agreement with bulk experiments. Atomistic modeling combined with extracted experimental parameters provides possible lattice sites for the 29Si atom under investigation. These results demonstrate that single 29Si nuclear spins could serve as a valuable resource in a silicon spin-based quantum computer.

  5. Uncovering many-body correlations in nanoscale nuclear spin baths by central spin decoherence.

    PubMed

    Ma, Wen-Long; Wolfowicz, Gary; Zhao, Nan; Li, Shu-Shen; Morton, John J L; Liu, Ren-Bao

    2014-01-01

    Central spin decoherence caused by nuclear spin baths is often a critical issue in various quantum computing schemes, and it has also been used for sensing single-nuclear spins. Recent theoretical studies suggest that central spin decoherence can act as a probe of many-body physics in spin baths; however, identification and detection of many-body correlations of nuclear spins in nanoscale systems are highly challenging. Here, taking a phosphorus donor electron spin in a (29)Si nuclear spin bath as our model system, we discover both theoretically and experimentally that many-body correlations in nanoscale nuclear spin baths produce identifiable signatures in decoherence of the central spin under multiple-pulse dynamical decoupling control. We demonstrate that under control by an odd or even number of pulses, the central spin decoherence is principally caused by second- or fourth-order nuclear spin correlations, respectively. This study marks an important step toward studying many-body physics using spin qubits. PMID:25205440

  6. Uncovering many-body correlations in nanoscale nuclear spin baths by central spin decoherence

    PubMed Central

    Ma, Wen-Long; Wolfowicz, Gary; Zhao, Nan; Li, Shu-Shen; Morton, John J.L.; Liu, Ren-Bao

    2014-01-01

    Central spin decoherence caused by nuclear spin baths is often a critical issue in various quantum computing schemes, and it has also been used for sensing single-nuclear spins. Recent theoretical studies suggest that central spin decoherence can act as a probe of many-body physics in spin baths; however, identification and detection of many-body correlations of nuclear spins in nanoscale systems are highly challenging. Here, taking a phosphorus donor electron spin in a 29Si nuclear spin bath as our model system, we discover both theoretically and experimentally that many-body correlations in nanoscale nuclear spin baths produce identifiable signatures in decoherence of the central spin under multiple-pulse dynamical decoupling control. We demonstrate that under control by an odd or even number of pulses, the central spin decoherence is principally caused by second- or fourth-order nuclear spin correlations, respectively. This study marks an important step toward studying many-body physics using spin qubits. PMID:25205440

  7. Robust control of individual nuclear spins in diamond

    E-print Network

    Benjamin Smeltzer; Jean McIntyre; Lilian Childress

    2009-09-22

    Isolated nuclear spins offer a promising building block for quantum information processing systems, but their weak interactions often impede preparation, control, and detection. Hyperfine coupling to a proximal electronic spin can enhance each of these processes. Using the electronic spin of the nitrogen-vacancy center as an intermediary, we demonstrate robust initialization, single-qubit manipulation, and direct optical readout of 13C, 15N, and 14N nuclear spins in diamond. These results pave the way for nitrogen nuclear spin based quantum information architectures in diamond.

  8. Coherence of single spins coupled to a nuclear spin bath of varying density

    E-print Network

    N. Mizuochi; P. Neumann; F. Rempp; J. Beck; V. Jacques; P. Siyushev; K. Nakamura; D. Twitchen; H. Watanabe; S. Yamasaki; F. Jelezko; J. Wrachtrup

    2009-05-05

    The dynamics of single electron and nuclear spins in a diamond lattice with different 13C nuclear spin concentration is investigated. It is shown that coherent control of up to three individual nuclei in a dense nuclear spin cluster is feasible. The free induction decays of nuclear spin Bell states and single nuclear coherences among 13C nuclear spins are compared and analyzed. Reduction of a free induction decay time T2* and a coherence time T2 upon increase of nuclear spin concentration has been found. For diamond material with depleted concentration of nuclear spin, T2* as long as 30 microseconds and T2 of up to 1.8 ms for the electron spin has been observed. The 13C concentration dependence of T2* is explained by Fermi contact and dipolar interactions with nuclei in the lattice. It has been found that T2 decreases approximately as 1/n, where n is 13C concentration, as expected for an electron spin interacting with a nuclear spin bath.

  9. Nuclear spin-state mixing in the NH2 radical

    Microsoft Academic Search

    A. R. Airne; A. S. Brill

    2001-01-01

    Nuclear spin-state mixing affects magnetic resonance and relaxation, thereby providing means to obtain information about molecular and electronic structure and, through spin polarization of nuclear targets, nucleon structure. In this report a calculation of matrix elements of the intramolecular nuclear spin-state mixing Hamiltonian is formulated and carried out for the proton (deuteron) and 14N (15N) nuclei in isotopes of the

  10. Decoherence of coupled electron spins via nuclear spin dynamics in quantum dots

    NASA Astrophysics Data System (ADS)

    Yang, W.; Liu, R. B.

    2008-02-01

    In double quantum dots, the exchange interaction between two electron spins renormalizes the excitation energy of pair flips in the nuclear spin bath, which in turn modifies the non-Markovian bath dynamics. As the energy renormalization varies with the static Overhauser field mismatch between the quantum dots, the electron singlet-triplet decoherence resulting from the bath dynamics depends on sampling of nuclear spin states from an ensemble, leading to the transition from superexponential decoherence in single-sample dynamics to power-law decay under ensemble averaging. In contrast, the decoherence of a single electron spin in one dot is essentially the same for different choices of the nuclear spin configuration.

  11. Solid state quantum memory using the 31P nuclear spin

    E-print Network

    John J. L. Morton; Alexei M. Tyryshkin; Richard M. Brown; Shyam Shankar; Brendon W. Lovett; Arzhang Ardavan; Thomas Schenkel; Eugene E. Haller; Joel W. Ager; S. A. Lyon

    2008-06-30

    The transfer of information between different physical forms is a central theme in communication and computation, for example between processing entities and memory. Nowhere is this more crucial than in quantum computation, where great effort must be taken to protect the integrity of a fragile quantum bit. Nuclear spins are known to benefit from long coherence times compared to electron spins, but are slow to manipulate and suffer from weak thermal polarisation. A powerful model for quantum computation is thus one in which electron spins are used for processing and readout while nuclear spins are used for storage. Here we demonstrate the coherent transfer of a superposition state in an electron spin 'processing' qubit to a nuclear spin 'memory' qubit, using a combination of microwave and radiofrequency pulses applied to 31P donors in an isotopically pure 28Si crystal. The electron spin state can be stored in the nuclear spin on a timescale that is long compared with the electron decoherence time and then coherently transferred back to the electron spin, thus demonstrating the 31P nuclear spin as a solid-state quantum memory. The overall store/readout fidelity is about 90%, attributed to systematic imperfections in radiofrequency pulses which can be improved through the use of composite pulses. We apply dynamic decoupling to protect the nuclear spin quantum memory element from sources of decoherence. The coherence lifetime of the quantum memory element is found to exceed one second at 5.5K.

  12. Nuclear spin pair coherence in diamond for atomic scale magnetometry

    E-print Network

    Nan Zhao; Jian-Liang Hu; Sai-Wah Ho; Tsz-Kai Wen; R. B. Liu

    2010-03-23

    The nitrogen-vacancy (NV) centre, as a promising candidate solid state system of quantum information processing, its electron spin coherence is influenced by the magnetic field fluctuations due to the local environment. In pure diamonds, the environment consists of hundreds of C-13 nuclear spins randomly spreading in several nanometers range forming a spin bath. Controlling and prolonging the electron spin coherence under the influence of spin bath are challenging tasks for the quantum information processing. On the other hand, for a given bath distribution, many of its characters are encoded in the electron spin coherence. So it is natural to ask the question: is it possible to 'decode' the electron spin coherence, and extract the information about the bath structures? Here we show that, among hundreds of C-13 bath spins, there exist strong coupling clusters, which give rise to the millisecond oscillations of the electron spin coherence. By analyzing these oscillation features, the key properties of the coherent nuclear spin clusters, such as positions, orientations, and coupling strengths, could be uniquely identified. This addressability of the few-nuclear-spin cluster extends the feasibility of using the nuclear spins in diamond as qubits in quantum computing. Furthermore, it provides a novel prototype of single-electron spin based, high-resolution and ultra-sensitive detector for the chemical and biological applications.

  13. Electronic Spin Storage in an Electrically Readable Nuclear Spin Memory with a Lifetime >100 Seconds

    NASA Astrophysics Data System (ADS)

    McCamey, D. R.; Van Tol, J.; Morley, G. W.; Boehme, C.

    2010-12-01

    Electron spins are strong candidates with which to implement spintronics because they are both mobile and able to be manipulated. The relatively short lifetimes of electron spins, however, present a problem for the long-term storage of spin information. We demonstrated an ensemble nuclear spin memory in phosphorous-doped silicon, which can be read out electrically and has a lifetime exceeding 100 seconds. The electronic spin information can be mapped onto and stored in the nuclear spin of the phosphorus donors, and the nuclear spins can then be repetitively read out electrically for time periods that exceed the electron spin lifetime. We discuss how this memory can be used in conjunction with other silicon spintronic devices.

  14. Nuclear magnetometry studies of spin dynamics in quantum Hall systems

    NASA Astrophysics Data System (ADS)

    Fauzi, M. H.; Watanabe, S.; Hirayama, Y.

    2014-12-01

    We performed a nuclear magnetometry study on quantum Hall ferromagnet with a bilayer total filling factor of ?tot=2 . We found not only a rapid nuclear relaxation but also a sudden change in the nuclear-spin polarization distribution after a one-second interaction with a canted antiferromagnetic phase. We discuss the possibility of observing cooperative phenomena coming from nuclear-spin ensemble triggered by hyperfine interaction in quantum Hall system.

  15. Electron Spin Dephasing and Decoherence by Interaction with Nuclear Spins in Self-Assembled Quantum Dots

    NASA Technical Reports Server (NTRS)

    Lee, Seungwon; vonAllmen, Paul; Oyafuso, Fabiano; Klimeck, Gerhard; Whale, K. Birgitta

    2004-01-01

    Electron spin dephasing and decoherence by its interaction with nuclear spins in self-assembled quantum dots are investigated in the framework of the empirical tight-binding model. Electron spin dephasing in an ensemble of dots is induced by the inhomogeneous precession frequencies of the electron among dots, while electron spin decoherence in a single dot arises from the inhomogeneous precession frequencies of nuclear spins in the dot. For In(x)Ga(1-x) As self-assembled dots containing 30000 nuclei, the dephasing and decoherence times are predicted to be on the order of 100 ps and 1 (micro)s.

  16. Dependence of nuclear spin singlet lifetimes on RF spin-locking power Stephen J. DeVience a,

    E-print Network

    Rosen, Matthew S

    Dependence of nuclear spin singlet lifetimes on RF spin-locking power Stephen J. DeVience a: Received 6 January 2012 Revised 14 March 2012 Available online 28 March 2012 Keywords: Nuclear singlet of long-lived nuclear spin singlet states as a function of the strength of the RF spin-locking field

  17. Orbital instabilities and spin-symmetry breaking in coupled-cluster calculations of indirect nuclear spin–spin coupling constants

    Microsoft Academic Search

    Alexander A. Auer; Jürgen Gauss

    2009-01-01

    The effect of orbital instabilities is investigated for spin-symmetry breaking perturbations, namely the Fermi-contact (FC) and spin–dipole (SD) contributions to the indirect nuclear spin–spin coupling constants. For the CO and N2 molecules the FC and SD contributions have been calculated and orbital-stability analyses for various interatomic distances have been carried out. This includes calculations at the Hartree–Fock self-consistent field (HF-SCF),

  18. Spin Modes in Nuclei and Nuclear Forces

    SciTech Connect

    Suzuki, Toshio [Department of Physics and Graduate School of Integrated Basic Sciences, College of Humanities and Sciences, Nihon University, Sakurajosui 3-25-40, Setagaya-ku, Tokyo 156-8550 (Japan) and Center for Nuclear Study, University of Tokyo, Hirosawa, Wako-shi, Saitama, 351-0198 (Japan); Otsuka, Takaharu [Department of Physics and Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2011-05-06

    Spin modes in stable and unstable exotic nuclei are studied and important roles of tensor and three-body forces on nuclear structure are discussed. New shell model Hamiltonians, which have proper tensor components, are shown to explain shell evolutions toward drip-lines and spin properties of both stable and exotic nuclei, for example, Gamow-Teller transitions in {sup 12}C and {sup 14}C and an anomalous M1 transition in {sup 17}C. The importance and the necessity of the repulsive monopole corrections in isospin T = 1 channel to the microscopic two-body interactions are pointed out. The corrections are shown to lead to the proper shell evolutions in neutron-rich isotopes. The three-body force, in particular the Fujita-Miyazawa force induced by {Delta} excitations, is pointed out to be responsible for the repulsive corrections among the valence neutrons. The important roles of the three-body force on the energies and transitions in exotic oxygen and calcium isotopes are demonstrated.

  19. Nuclear spin pair coherence in diamond for atomic scale magnetometry

    E-print Network

    Zhao, Nan; Ho, Sai-Wah; Wen, Tsz-Kai; Liu, R B

    2010-01-01

    The nitrogen-vacancy (NV) centre, as a promising candidate solid state system of quantum information processing, its electron spin coherence is influenced by the magnetic field fluctuations due to the local environment. In pure diamonds, the environment consists of hundreds of C-13 nuclear spins randomly spreading in several nanometers range forming a spin bath. Controlling and prolonging the electron spin coherence under the influence of spin bath are challenging tasks for the quantum information processing. On the other hand, for a given bath distribution, many of its characters are encoded in the electron spin coherence. So it is natural to ask the question: is it possible to 'decode' the electron spin coherence, and extract the information about the bath structures? Here we show that, among hundreds of C-13 bath spins, there exist strong coupling clusters, which give rise to the millisecond oscillations of the electron spin coherence. By analyzing these oscillation features, the key properties of the cohe...

  20. Fast Electrical Control of Single Electron Spins in Quantum Dots with Vanishing Influence from Nuclear Spins

    NASA Astrophysics Data System (ADS)

    Yoneda, J.; Otsuka, T.; Nakajima, T.; Takakura, T.; Obata, T.; Pioro-Ladrière, M.; Lu, H.; Palmstrøm, C. J.; Gossard, A. C.; Tarucha, S.

    2014-12-01

    We demonstrate fast universal electrical spin manipulation with inhomogeneous magnetic fields. With fast Rabi frequency up to 127 MHz, we leave the conventional regime of strong nuclear-spin influence and observe a spin-flip fidelity >96 % , a distinct chevron Rabi pattern in the spectral-time domain, and a spin resonance linewidth limited by the Rabi frequency, not by the dephasing rate. In addition, we establish fast z rotations up to 54 MHz by directly controlling the spin phase. Our findings will significantly facilitate tomography and error correction with electron spins in quantum dots.

  1. Uncovering many-body correlations in nanoscale nuclear spin baths by central spin decoherence

    E-print Network

    Wen-Long Ma; Gary Wolfowicz; Nan Zhao; Shu-Shen Li; John J. L. Morton; Ren-Bao Liu

    2014-04-10

    Many-body correlations can yield key insights into the nature of interacting systems; however, detecting them is often very challenging in many-particle physics, especially in nanoscale systems. Here, taking a phosphorus donor electron spin in a natural-abundance 29Si nuclear spin bath as our model system, we discover both theoretically and experimentally that many-body correlations in nanoscale nuclear spin baths produce identifiable signatures in the decoherence of the central spin under multiple-pulse dynamical decoupling control. We find that when the number of decoupling -pulses is odd, central spin decoherence is primarily driven by second-order nuclear spin correlations (pairwise flip-flop processes). In contrast, when the number of -pulses is even, fourth-order nuclear spin correlations (diagonal interaction renormalized pairwise flip-flop processes) are principally responsible for the central spin decoherence. Many-body correlations of different orders can thus be selectively detected by central spin decoherence under different dynamical decoupling controls, providing a useful approach to probing many-body processes in nanoscale nuclear spin baths.

  2. Decoherence of proximate nuclear spin qubits in natural silicon

    E-print Network

    R. Guichard; S. J. Balian; G. Wolfowicz; P. A. Mortemousque; John J. L. Morton; T. S. Monteiro

    2015-03-14

    Hybrid qubit systems combining electronic spins with surrounding proximate nuclear spins registers offer a promising avenue towards quantum information processing, with even multi-spin error correction protocols recently demonstrated in diamond. For the important platform offered by cryogenically cooled spins of donors in natural silicon such as phosphorus Si:P, however, the coherence behaviour of proximate nuclear spins are not well understood. We propose here that there may be an important contribution from a few (of order 100 spin pairs) symmetrically sited nuclear spin impurity pairs ("equivalent pairs"), which were not previously considered, as their effect is negligible outside the frozen core around an electron. If equivalent pairs represent a measurable source of decoherence, nuclear coherence decays could provide sensitive probes of the symmetries of electronic wavefunctions. We compare this model with the effect of a very large nuclear spin bath (10^8 weakly contributing pairs) outside the frozen core. We obtain T_{2n} values of order 1 second for both models, confirming the suitability of proximate nuclei in silicon as very long-lived spin qubits, in either case.

  3. Room temperature hyperpolarization of nuclear spins in bulk

    PubMed Central

    Tateishi, Kenichiro; Negoro, Makoto; Nishida, Shinsuke; Kagawa, Akinori; Morita, Yasushi; Kitagawa, Masahiro

    2014-01-01

    Dynamic nuclear polarization (DNP), a means of transferring spin polarization from electrons to nuclei, can enhance the nuclear spin polarization (hence the NMR sensitivity) in bulk materials at most 660 times for 1H spins, using electron spins in thermal equilibrium as polarizing agents. By using electron spins in photo-excited triplet states instead, DNP can overcome the above limit. We demonstrate a 1H spin polarization of 34%, which gives an enhancement factor of 250,000 in 0.40 T, while maintaining a bulk sample (?0.6 mg, ?0.7 × 0.7 × 1 mm3) containing >1019 1H spins at room temperature. Room temperature hyperpolarization achieved with DNP using photo-excited triplet electrons has potentials to be applied to a wide range of fields, including NMR spectroscopy and MRI as well as fundamental physics. PMID:24821773

  4. Nuclear spin-induced Cotton-Mouton effect in molecules

    NASA Astrophysics Data System (ADS)

    Fu, Li-juan; Vaara, Juha

    2013-05-01

    In nuclear magneto-optic spectroscopy, effects of nuclear magnetization are detected in light passing through a sample containing spin-polarized nuclei. An optical analogue of nuclear magnetic resonance (NMR) chemical shift has been predicted and observed in the nuclear spin optical rotation of linearly polarized light propagating parallel to the nuclear magnetization. A recently proposed magneto-optic analogue of the NMR spin-spin coupling, the nuclear spin-induced Cotton-Mouton (NSCM) effect entails an ellipticity induced to linearly polarized light when passing through a medium with the nuclear spins polarized in a direction perpendicular to the light beam. Here we present a first-principles electronic structure formulation of NSCM in terms of response theory as well as ab initio and density-functional theory calculations for small molecules. The roles of basis set (we use completeness-optimized sets), electron correlation, and relativistic effects are discussed. It is found that the explicitly temperature-dependent contribution to NSCM, arising from the partial orientation of the molecules due to the nuclear magnetization, typically dominates the effect. This part of NSCM is proportional to the tensor product of molecular polarizability and the NMR direct dipolar coupling tensor. Hence, NSCM provides a means of investigating the dipolar coupling and, thus, molecular structure in a formally isotropic medium. Overall ellipticities of the order of magnitude of 10-8…10-7 rad/(M cm) are predicted for fully polarized nuclei. These should be detectable with modern instrumentation in the Voigt setup.

  5. Engineering Nuclear spin has now been associated with Nobel Prizes

    E-print Network

    Chemical Engineering Nuclear spin has now been associated with Nobel Prizes in Physics, Chemistry-2003, Professor Reimer won the Donald Sterling Noyce Prize, the AIChE Northern California Section Award and the UC

  6. Nuclear magnetic resonance spectroscopy with single spin sensitivity

    NASA Astrophysics Data System (ADS)

    Müller, C.; Kong, X.; Cai, J.-M.; Melentijevi?, K.; Stacey, A.; Markham, M.; Twitchen, D.; Isoya, J.; Pezzagna, S.; Meijer, J.; Du, J. F.; Plenio, M. B.; Naydenov, B.; McGuinness, L. P.; Jelezko, F.

    2014-08-01

    Nuclear magnetic resonance spectroscopy and magnetic resonance imaging at the ultimate sensitivity limit of single molecules or single nuclear spins requires fundamentally new detection strategies. The strong coupling regime, when interaction between sensor and sample spins dominates all other interactions, is one such strategy. In this regime, classically forbidden detection of completely unpolarized nuclei is allowed, going beyond statistical fluctuations in magnetization. Here we realize strong coupling between an atomic (nitrogen-vacancy) sensor and sample nuclei to perform nuclear magnetic resonance on four 29Si spins. We exploit the field gradient created by the diamond atomic sensor, in concert with compressed sensing, to realize imaging protocols, enabling individual nuclei to be located with Angstrom precision. The achieved signal-to-noise ratio under ambient conditions allows single nuclear spin sensitivity to be achieved within seconds.

  7. Nuclear magnetic resonance spectroscopy with single spin sensitivity

    PubMed Central

    Müller, C.; Kong, X.; Cai, J.-M.; Melentijevi?, K.; Stacey, A.; Markham, M.; Twitchen, D.; Isoya, J.; Pezzagna, S.; Meijer, J.; Du, J. F.; Plenio, M. B.; Naydenov, B.; McGuinness, L. P.; Jelezko, F.

    2014-01-01

    Nuclear magnetic resonance spectroscopy and magnetic resonance imaging at the ultimate sensitivity limit of single molecules or single nuclear spins requires fundamentally new detection strategies. The strong coupling regime, when interaction between sensor and sample spins dominates all other interactions, is one such strategy. In this regime, classically forbidden detection of completely unpolarized nuclei is allowed, going beyond statistical fluctuations in magnetization. Here we realize strong coupling between an atomic (nitrogen–vacancy) sensor and sample nuclei to perform nuclear magnetic resonance on four 29Si spins. We exploit the field gradient created by the diamond atomic sensor, in concert with compressed sensing, to realize imaging protocols, enabling individual nuclei to be located with Angstrom precision. The achieved signal-to-noise ratio under ambient conditions allows single nuclear spin sensitivity to be achieved within seconds. PMID:25146503

  8. Optical hyperpolarization of 13C nuclear spins in nanodiamond ensembles

    E-print Network

    Q. Chen; I. Schwarz; F. Jelezko; A. Retzker; M. B. Plenio

    2015-04-09

    Here we propose and analyse in detail protocols that can achieve rapid hyperpolarization of 13C nuclear spins in randomly oriented ensembles of nanodiamonds at room temperature. Our protocols exploit a combination of optical polarization of electron spins in nitrogen-vacancy centers and the transfer of this polarization to 13C nuclei by means of microwave control to overcome the severe challenges that are posed by the random orientation of the nanodiamonds and their nitrogen-vacancy centers. Specifically, these random orientations result in exceedingly large energy variations of the electron spin levels that render the polarization and coherent control of the nitrogen-vacancy center electron spins as well as the control of their coherent interaction with the surrounding 13C nuclear spins highly inefficient. We address these challenges by a combination of an off-resonant microwave double resonance scheme in conjunction with a realization of the integrated solid effect which, together with adiabatic rotations of external magnetic fields or rotations of nanodiamonds, leads to a protocol that achieves high levels of hyperpolarization of the entire nuclear-spin bath in a randomly oriented ensemble of nanodiamonds even at room temperature. This hyperpolarization together with the long nuclear spin polarization lifetimes in nanodiamonds and the relatively high density of 13C nuclei has the potential to result in a major signal enhancement in 13C nuclear magnetic resonance imaging and suggests functionalized and hyperpolarized nanodiamonds as a unique probe for molecular imaging both in vitro and in vivo.

  9. Polarization of nuclear spins by a cold nanoscale resonator

    SciTech Connect

    Butler, Mark C.; Weitekamp, Daniel P. [A. A. Noyes Laboratory of Chemical Physics, California Institute of Technology, MC 127-72, Pasadena, California 91125 (United States)

    2011-12-15

    A cold nanoscale resonator coupled to a system of nuclear spins can induce spin relaxation. In the low-temperature limit where spin-lattice interactions are ''frozen out,'' spontaneous emission by nuclear spins into a resonant mechanical mode can become the dominant mechanism for cooling the spins to thermal equilibrium with their environment. We provide a theoretical framework for the study of resonator-induced cooling of nuclear spins in this low-temperature regime. Relaxation equations are derived from first principles, in the limit where energy donated by the spins to the resonator is quickly dissipated into the cold bath that damps it. A physical interpretation of the processes contributing to spin polarization is given. For a system of spins that have identical couplings to the resonator, the interaction Hamiltonian conserves spin angular momentum, and the resonator cannot relax the spins to thermal equilibrium unless this symmetry is broken by the spin Hamiltonian. The mechanism by which such a spin system becomes ''trapped'' away from thermal equilibrium can be visualized using a semiclassical model, which shows how an indirect spin-spin interaction arises from the coupling of multiple spins to one resonator. The internal spin Hamiltonian can affect the polarization process in two ways: (1) By modifying the structure of the spin-spin correlations in the energy eigenstates, and (2) by splitting the degeneracy within a manifold of energy eigenstates, so that zero-frequency off-diagonal terms in the density matrix are converted to oscillating coherences. Shifting the frequencies of these coherences sufficiently far from zero suppresses the development of resonator-induced correlations within the manifold during polarization from a totally disordered state. Modification of the spin-spin correlations by means of either mechanism affects the strength of the fluctuating spin dipole that drives the resonator. In the case where product states can be chosen as energy eigenstates, spontaneous emission from eigenstate populations into the resonant mode can be interpreted as independent emission by individual spins, and the spins relax exponentially to thermal equilibrium if the development of resonator-induced correlations is suppressed. When the spin Hamiltonian includes a significant contribution from the homonuclear dipolar coupling, the energy eigenstates entail a correlation specific to the coupling network. Simulations of dipole-dipole coupled systems of up to five spins suggest that these systems contain weakly emitting eigenstates that can trap a fraction of the population for time periods >>100/R{sub 0}, where R{sub 0} is the rate constant for resonator-enhanced spontaneous emission by a single spin 1/2. Much of the polarization, however, relaxes with rates comparable to R{sub 0}. A distribution of characteristic high-field chemical shifts tends to increase the relaxation rates of weakly emitting states, enabling transitions to states that can quickly relax to thermal equilibrium. The theoretical framework presented in this paper is illustrated with discussions of spin polarization in the contexts of force-detected nuclear-magnetic-resonance spectroscopy and magnetic-resonance force microscopy.

  10. Nuclear Spins in a Nanoscale Device for Quantum Information Processing

    E-print Network

    S. K. Ozdemir; A. Miranowicz; T. Ota; G. Yusa; N. Imoto; Y. Hirayama

    2006-12-29

    Coherent oscillations between any two levels from four nuclear spin states of I=3/2 have been demonstrated in a nanometre-scale NMR semiconductor device, where nuclear spins are all-electrically controlled. Using this device, we discuss quantum logic operations on two fictitious qubits of the I=3/2 system, and propose a quantum state tomography scheme based on the measurement of longitudinal magnetization, $M_z$.

  11. Nuclear spin qubits in a trapped-ion quantum computer

    E-print Network

    M. Feng; Y. Y. Xu; F. Zhou; D. Suter

    2009-04-26

    Physical systems must fulfill a number of conditions to qualify as useful quantum bits (qubits) for quantum information processing, including ease of manipulation, long decoherence times, and high fidelity readout operations. Since these conditions are hard to satisfy with a single system, it may be necessary to combine different degrees of freedom. Here we discuss a possible system, based on electronic and nuclear spin degrees of freedom in trapped ions. The nuclear spin yields long decoherence times, while the electronic spin, in a magnetic field gradient, provides efficient manipulation, and the optical transitions of the ions assure a selective and efficient initialization and readout.

  12. Nuclear-spin observation of noise spectra in semiconductors

    SciTech Connect

    Sasaki, Susumu; Nishimori, Masashi; Kawanago, Takashi [Department of Materials Science, Niigata University, Niigata 950-2181 (Japan); Yuge, Tatsuro [Yukawa Institute for Theoretical Physics, Kyoto University, Kyoto 606-8502 (Japan); Hirayama, Yoshiro [Department of Physics, Tohoku University, Sendai 980-8578, Japan and JST-ERATO Nuclear Spin Electronics Project, Sendai 980-8578 (Japan)

    2013-12-04

    We propose a systematic method of obtaining the spectra of noises that cause the decoherence of spins in solids. Based on this method, we experimentally show that this method can be applied to nuclear spins in semiconductors. We clarify that the spectral intensity must be derived from the long-time tail of the multiple-echo decay. To obtain higher-frequency noise, the inversion-pulse interval must be as short as possible, which required us to employ the alternating-phase Carr-Purcell sequence instead of the widely used Carr-Purcell Meiboom-Gill. For {sup 75}As nuclear spin in variously-doped GaAs, we observed a Lorentzian spectrum, instead of the commonly observed 1/f spectrum. This indicates that the nuclear spins are indeed in a coherently-controlled state.

  13. Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics

    E-print Network

    Seager, Sara

    Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics (Dated: February 5, 2014) In this experiment, the phenomenon of Nuclear Magnetic Resonance (NMR) is used to determine the magnetic moments that a particle with angular momentum I and magnetic moment µ = I placed in a uniform mag- netic field B0

  14. High spin nuclear structure studies using the spin spectrometer

    Microsoft Academic Search

    1986-01-01

    The gamma-gamma correlation technique is used to generate two-dimensional histograms of gamma ray energy from gamma-gamma coincidence data. The spin spectrometer at Oak Ridge National Laboratory is used to study the continuum gamma-rays from the reaction ¹°°Mo + ³⁴S at 144 MeV beam energy. Double and triple correlation spectra for transitions in rotational bands are obtained which exhibit characteristic valleys.

  15. Calculation of nuclear spin-spin coupling constants using frozen density embedding

    SciTech Connect

    Götz, Andreas W., E-mail: agoetz@sdsc.edu [San Diego Supercomputer Center, University of California San Diego, 9500 Gilman Dr MC 0505, La Jolla, California 92093-0505 (United States); Autschbach, Jochen [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000 (United States)] [Department of Chemistry, University at Buffalo, State University of New York, Buffalo, New York 14260-3000 (United States); Visscher, Lucas, E-mail: visscher@chem.vu.nl [Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, Theoretical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands)] [Amsterdam Center for Multiscale Modeling (ACMM), VU University Amsterdam, Theoretical Chemistry, De Boelelaan 1083, 1081 HV Amsterdam (Netherlands)

    2014-03-14

    We present a method for a subsystem-based calculation of indirect nuclear spin-spin coupling tensors within the framework of current-spin-density-functional theory. Our approach is based on the frozen-density embedding scheme within density-functional theory and extends a previously reported subsystem-based approach for the calculation of nuclear magnetic resonance shielding tensors to magnetic fields which couple not only to orbital but also spin degrees of freedom. This leads to a formulation in which the electron density, the induced paramagnetic current, and the induced spin-magnetization density are calculated separately for the individual subsystems. This is particularly useful for the inclusion of environmental effects in the calculation of nuclear spin-spin coupling constants. Neglecting the induced paramagnetic current and spin-magnetization density in the environment due to the magnetic moments of the coupled nuclei leads to a very efficient method in which the computationally expensive response calculation has to be performed only for the subsystem of interest. We show that this approach leads to very good results for the calculation of solvent-induced shifts of nuclear spin-spin coupling constants in hydrogen-bonded systems. Also for systems with stronger interactions, frozen-density embedding performs remarkably well, given the approximate nature of currently available functionals for the non-additive kinetic energy. As an example we show results for methylmercury halides which exhibit an exceptionally large shift of the one-bond coupling constants between {sup 199}Hg and {sup 13}C upon coordination of dimethylsulfoxide solvent molecules.

  16. Towards understanding global variability in ocean carbon-13

    Microsoft Academic Search

    Alessandro Tagliabue; Laurent Bopp

    2008-01-01

    We include a prognostic parameterization of carbon-13 into a global ocean-biogeochemistry model to investigate the spatiotemporal variability in ocean carbon-13 between 1860 and 2000. Carbon-13 was included in all 10 existing carbon pools, with dynamic fractionations occurring during photosynthesis, gas exchange and carbonate chemistry. We find that ocean distributions of ?13CDIC at any point in time are controlled by the

  17. High spin nuclear structure studies using the spin spectrometer

    SciTech Connect

    Lee, I.Y.

    1986-01-01

    The gamma-gamma correlation technique is used to generate two-dimensional histograms of gamma ray energy from gamma-gamma coincidence data. The spin spectrometer at Oak Ridge National Laboratory is used to study the continuum gamma-rays from the reaction /sup 100/Mo + /sup 34/S at 144 MeV beam energy. Double and triple correlation spectra for transitions in rotational bands are obtained which exhibit characteristic valleys. These valleys are shown to depend on the moment of inertia of the rotational bands and the gamma ray spreading width. 5 refs., 4 figs., 4 tabs. (DWL)

  18. Concerted two-dimensional NMR approaches to hydrogen-1, carbon-13, and nitrogen-15 resonance assignments in proteins

    SciTech Connect

    Stockman, B.J.; Reily, M.D.; Westler, W.M.; Ulrich, E.L.; Markley, J.L. (Univ. of Wisconsin, Madison (USA))

    1989-01-10

    When used in concert, one-bond carbon-carbon correlations, one-bond and multiple-bond proton-carbon correlations, and multiple-bond proton-nitrogen correlations, derived from two-dimensional (2D) NMR spectra of isotopically enriched proteins, provide a reliable method of assigning proton, carbon, and nitrogen resonances. In contrast to procedures that simply extend proton assignments to carbon or nitrogen resonances, this technique assigns proton, carbon, and nitrogen resonances coordinately on the basis of their integrated coupling networks. Redundant spin coupling pathways provide ways of resolving overlaps frequently encountered in homonuclear {sup 1}H 2D NMR spectra and facilitate the elucidation of complex proton spin systems. Carbon-carbon and proton-carbon couplings can be used to bridge the aromatic and aliphatic parts of proton spin systems; this avoids possible ambiguities that may result from the use of nuclear Overhauser effects to assign aromatic amino acid signals. The technique is illustrated for Anabaena 7120 flavodoxin and cytochrome c-553, both uniformly enriched with carbon-13 (26%) or nitrogen-15 (98%).

  19. Spin echo decay at low magnetic fields in a nuclear spin bath

    E-print Network

    L. Cywinski; V. V. Dobrovitski; S. Das Sarma

    2010-07-23

    We investigate theoretically the spin echo signal of an electron localized in a quantum dot and interacting with a bath of nuclear spins. We consider the regime of very low magnetic fields (corresponding to fields as low as a militesla in realistic GaAs and InGaAs dots). We use both the exact numerical simulations and the analytical theory employing the effective pure dephasing Hamiltonian. The comparison shows that the latter approach describes very well the spin echo decay at magnetic fields larger than the typical Overhauser field, and that the timescale at which this theory works is larger than previously expected. The numerical simulations are also done for very low values of electron spin splitting at which the effective Hamiltonian based theory fails quantitatively. Interestingly, the qualitative difference in the spin echo decay between the cases of a homonuclear and a heteronuclear bath (i.e. bath containing nuclear isotopes having different Zeeman energies), predicted previously using the effective Hamiltonian approach, is still visible at very low fields outside the regime of applicability of the analytical theory. We have found that the spin echo signal for a homonuclear bath oscillates with a frequency corresponding to the Zeeman splitting of the single nuclear isotope present in the bath. The physics behind this feature is similar to that of the electron spin echo envelope modulation (ESEEM). While purely isotropic hyperfine interactions are present in our system, the tilting of the electron precession axis at low fields may explain this result.

  20. Fast Room-Temperature Phase Gate on a Single Nuclear Spin in Diamond

    NASA Astrophysics Data System (ADS)

    Sangtawesin, S.; Brundage, T. O.; Petta, J. R.

    2014-07-01

    Nuclear spins support long lived quantum coherence due to weak coupling to the environment, but are difficult to rapidly control using nuclear magnetic resonance as a result of the small nuclear magnetic moment. We demonstrate a fast ˜500 ns nuclear spin phase gate on a N14 nuclear spin qubit intrinsic to a nitrogen-vacancy center in diamond. The phase gate is enabled by the hyperfine interaction and off-resonance driving of electron spin transitions. Repeated applications of the phase gate bang-bang decouple the nuclear spin from the environment, locking the spin state for up to ˜140 ?s.

  1. Single shot NMR on single, dark nuclear spins

    E-print Network

    Waldherr, G; Steiner, M; Neumann, P; Gali, A; Jelezko, F; Wrachtrup, J

    2010-01-01

    The electron and nuclear spins associated with the nitrogen-vacancy (NV) center in diamond are supposed to be building blocks for quantum computing devices and nanometer scale magnetometry operating under ambient conditions. For every such building block precise knowledge of the involved quantum states is crucial. Especially for solid state systems the corresponding hilbert space can be large. Here, we experimentally show that under usual operating conditions the NV color center exists in an equilibrium of two charge states (i.e. 70% in the usually used negative (NV-) and 30% in the neutral one (NV0)). Projective quantum non-demolition measurement of the nitrogen nuclear spin enables the detection even of the additional, optically inactive state. It turns out that the nuclear spin can be coherently driven also in NV0. However, its T1 ~ 90 ms and T2 ~ 6micro-s times are much shorter than in NV-, supposedly because of the dynamic Jahn-Teller effect.

  2. Quantum and classical correlations in electron-nuclear spin echo

    SciTech Connect

    Zobov, V. E., E-mail: rsa@iph.krasn.ru [Russian Academy of Sciences, Kirensky Institute of Physics, Siberian Branch (Russian Federation)

    2014-11-15

    The quantum properties of dynamic correlations in a system of an electron spin surrounded by nuclear spins under the conditions of free induction decay and electron spin echo have been studied. Analytical results for the time evolution of mutual information, classical part of correlations, and quantum part characterized by quantum discord have been obtained within the central-spin model in the high-temperature approximation. The same formulas describe discord in both free induction decay and spin echo although the time and magnetic field dependences are different because of difference in the parameters entering into the formulas. Changes in discord in the presence of the nuclear polarization ?{sub I} in addition to the electron polarization ?{sub S} have been calculated. It has been shown that the method of reduction of the density matrix to a two-spin electron-nuclear system provides a qualitatively correct description of pair correlations playing the main role at ?{sub S} ? ?{sub I} and small times. At large times, such correlations decay and multispin correlations ensuring nonzero mutual information and zero quantum discord become dominant.

  3. A Magnetic Switch for Spin-Catalyzed Interconversion of Nuclear Spin Yongjun Li,

    E-print Network

    Turro, Nicholas J.

    A Magnetic Switch for Spin-Catalyzed Interconversion of Nuclear Spin Isomers Yongjun Li, Xuegong guest@host complexes2­4 oH2@C60 and pH2@C60, respectively. We have developed5 the following procedure catalysts for the back conversion of *pH2@C60 to eH2@C60.5 We reasoned that if a derivative of H2@C60 could

  4. Spin dynamics of a confined electron interacting with magnetic or nuclear spins: A semiclassical approach

    NASA Astrophysics Data System (ADS)

    Dietl, Tomasz

    2015-03-01

    A physically transparent and mathematically simple semiclassical model is employed to examine dynamics in the central-spin problem. The results reproduce previous findings obtained by various quantum approaches and, at the same time, provide information on the electron spin dynamics and Berry's phase effects over a wider range of experimentally relevant parameters than available previously. This development is relevant to dynamics of bound magnetic polarons and spin dephasing of an electron trapped by an impurity or a quantum dot, and coupled by a contact interaction to neighboring localized magnetic impurities or nuclear spins. Furthermore, it substantiates the applicability of semiclassical models to simulate dynamic properties of spintronic nanostructures with a mesoscopic number of spins.

  5. Dynamic nuclear polarization from current-induced electron spin polarization

    NASA Astrophysics Data System (ADS)

    Trowbridge, C. J.; Norman, B. M.; Kato, Y. K.; Awschalom, D. D.; Sih, V.

    2014-08-01

    Current-induced electron spin polarization is shown to produce nuclear hyperpolarization through dynamic nuclear polarization. Saturated fields of several millitesla are generated upon the application of an electric field over a time scale of 100 s in InGaAs epilayers and measured using optical Larmor magnetometry. We show that, in contrast to previous demonstrations of current-induced dynamic nuclear polarization, the direction of the current relative to the crystal axis and external magnetic field may be used to control the magnitude and direction of the saturation nuclear field.

  6. Quantum Information Transport in Nuclear Spin Chains

    Microsoft Academic Search

    Paola Cappellaro; David Cory

    2007-01-01

    In many solid-state proposals for quantum computers, the transport of information over relatively short distances inside the quantum processor itself is an essential task, and one for which relying on photons, and therefore on a frequent exchanging of information between solid-state and light qubits, could be too costly. Quantum wires based on spins could be a viable alternative leading to

  7. Dynamics of a mesoscopic nuclear spin ensemble interacting with an optically driven electron spin

    NASA Astrophysics Data System (ADS)

    Stanley, M. J.; Matthiesen, C.; Hansom, J.; Le Gall, C.; Schulte, C. H. H.; Clarke, E.; Atatüre, M.

    2014-11-01

    The ability to discriminate between simultaneously occurring noise sources in the local environment of semiconductor InGaAs quantum dots, such as electric and magnetic field fluctuations, is key to understanding their respective dynamics and their effect on quantum dot coherence properties. We present a discriminatory approach to all-optical sensing based on two-color resonance fluorescence of a quantum dot charged with a single electron. Our measurements show that local magnetic field fluctuations due to nuclear spins in the absence of an external magnetic field are described by two correlation times, both in the microsecond regime. The nuclear spin bath dynamics show a strong dependence on the strength of resonant probing, with correlation times increasing by a factor of 4 as the optical transition is saturated. We interpret the behavior as motional averaging of both the Knight field of the resident electron spin and the hyperfine-mediated nuclear spin-spin interaction due to optically induced electron spin flips.

  8. Dynamics of a mesoscopic nuclear spin ensemble interacting with an optically driven electron spin

    E-print Network

    Megan J. Stanley; Clemens Matthiesen; Jack Hansom; Claire Le Gall; Carsten H. H. Schulte; Edmund Clarke; Mete Atatüre

    2014-11-17

    The ability to discriminate between simultaneously occurring noise sources in the local environment of semiconductor InGaAs quantum dots, such as electric and magnetic field fluctuations, is key to understanding their respective dynamics and their effect on quantum dot coherence properties. We present a discriminatory approach to all-optical sensing based on two-color resonance fluorescence of a quantum dot charged with a single electron. Our measurements show that local magnetic field fluctuations due to nuclear spins in the absence of an external magnetic field are described by two correlation times, both in the microsecond regime. The nuclear spin bath dynamics show a strong dependence on the strength of resonant probing, with correlation times increasing by a factor of four as the optical transition is saturated. We interpret the behavior as motional averaging of both the Knight field of the resident electron spin and the hyperfine-mediated nuclear spin-spin interaction due to optically-induced electron spin flips.

  9. Coherent control of hyperfine-coupled electron and nuclear spins for quantum information processing

    E-print Network

    Yang, Jamie Chiaming

    2008-01-01

    Coupled electron-nuclear spins are promising physical systems for quantum information processing: By combining the long coherence times of the nuclear spins with the ability to initialize, control, and measure the electron ...

  10. Ultrafast Nuclear Spin Polarization by Short Laser Pulses

    SciTech Connect

    Nakajima, Takashi [Institute of Advanced Energy, Kyoto University Gokasho, Uji, Kyoto 611-0011 (Japan)

    2008-02-06

    We propose a novel scheme to realize ultrafast nuclear spin polarization by short laser pulses. Combined use of the hyperfine interaction and the static electric field is the key for that. The idea is specifically applied to various isotopes of alkaline-earth atoms, Mg and Ca, with nuclear spin I = 1/2, 3/2, 5/2, and 7/2. After the detailed theoretical analysis, we find that spin-polarization as high as 88%, 66%, 33%, and 25%, respectively, for I = 1/2, 3/2, 5/2, and 7/2, can be attained in the time scale of a few to tens of ns, which is at least 2-3 orders of magnitude shorter than any known optical methods. Due to this ultrafast nature, our scheme is applicable not only for stable nuclei but also unstable nuclei with a lifetime as short as a few {mu}s.

  11. Longitudinal spin-dependent correlations in nuclear matter

    NASA Astrophysics Data System (ADS)

    Fabrocini, A.; Fantoni, S.

    1981-04-01

    A Jastrow-type wave function, with the two-body correlation factor depending on the spin-isospin state of the particles, is used for variational calculations of the energy per particle of infinite Fermi systems. Results are presented for nuclear matter and neutron matter using two semi-realistic potentials.

  12. Enrichment of nuclear spin isomers of molecules by bichromatic field

    NASA Astrophysics Data System (ADS)

    Chapovsky, P. L.; Wilson-Gordon, A. D.

    2015-03-01

    A theoretical model for the enrichment of nuclear spin isomers of molecules by two electromagnetic fields is developed. The fields are resonant with the rotational transitions in the ground electronic and vibrational state of the molecule. Numerical calculations reveal a complicated dependence of the isomer enrichment on the radiation frequencies that consists of three peaks with different shapes, widths and amplitudes.

  13. A silicon-based nuclear spin quantum computer

    Microsoft Academic Search

    B. E. Kane

    1998-01-01

    Quantum computers promise to exceed the computational efficiency of ordinary classical machines because quantum algorithms allow the execution of certain tasks in fewer steps. But practical implementation of these machines poses a formidable challenge. Here I present a scheme for implementing a quantum-mechanical computer. Information is encoded onto the nuclear spins of donor atoms in doped silicon electronic devices. Logical

  14. Spins as qubits: Quantum information processing by nuclear magnetic resonance

    E-print Network

    Suter, Dieter

    of the amount of energy dissipated per logical operation in successive generations of computer hardware. SomeSpins as qubits: Quantum information processing by nuclear magnetic resonance Dieter Suter1,a and T 2007; published online 5 February 2008 Storing information in quantum mechanical degrees of freedom

  15. Nuclear Spin Gyroscope Based on an Atomic Comagnetometer

    SciTech Connect

    Kornack, T.W.; Ghosh, R.K.; Romalis, M.V. [Department of Physics, Princeton University, Princeton, New Jersey 08550 (United States)

    2005-12-02

    We describe a nuclear spin gyroscope based on an alkali-metal-noble-gas comagnetometer. Optically pumped alkali-metal vapor is used to polarize the noble-gas atoms and detect their gyroscopic precession. Spin precession due to magnetic fields as well as their gradients and transients can be cancelled in this arrangement. The sensitivity is enhanced by using a high-density alkali-metal vapor in a spin-exchange relaxation free regime. With a K-{sup 3}He comagnetometer we demonstrate rotation sensitivity of 5x10{sup -7} rad s{sup -1} Hz{sup -1/2}, equivalent to a magnetic field sensitivity of 2.5 fT/Hz{sup 1/2}. The rotation signal can be increased by a factor of 10 using {sup 21}Ne with a smaller magnetic moment. The comagnetometer is also a promising tool in searches for anomalous spin couplings beyond the standard model.

  16. Engineering nuclear spin dynamics with optically pumped nitrogen-vacancy center

    E-print Network

    Ping Wang; Jiangfeng Du; Wen Yang

    2015-03-01

    We present a general theory for using an optically pumped diamond nitrogen-vacancy center as a tunable, non-equilibrium bath to control a variety of nuclear spin dynamics (such as dephasing, relaxation, squeezing, polarization, etc.) and the nuclear spin noise. It opens a new avenue towards engineering the dissipative and collective nuclear spin evolution and solves an open problem brought up by the $^{13}$C nuclear spin noise suppression experiment [E. Togan \\textit{et al}., Nature 478, 497 (2011)].

  17. Quantum read-out and fast initialization of nuclear spin qubits with electric currents

    E-print Network

    Noah Stemeroff; Rogerio de Sousa

    2011-10-01

    Nuclear spin qubits have the longest coherence times in the solid state, but their quantum read-out and initialization is a great challenge. We present a theory for the interaction of an electric current with the nuclear spins of donor impurities in semiconductors. The theory yields a sensitivity criterion for quantum detection of nuclear spin states using electrically detected magnetic resonance, as well as an all electrical method for fast nuclear spin qubit initialization.

  18. Nuclear moments of inertia at high spin

    SciTech Connect

    Deleplanque, M.A.

    1982-10-01

    The competition between collective motion and alignment at high spin can be evaluated by measuring two complementary dynamic moments of inertia. The first, I band, measured in ..gamma..-..gamma.. correlation experiments, relates to the collective properties of the nucleus. A new moment of inertia I/sub eff/ is defined here, which contains both collective and alignment effects. Both of these can be measured in continuum ..gamma..-ray spectra of rotational nuclei up to high frequencies. The evolution of ..gamma..-ray spectra for Er nuclei from mass 160 to 154 shows that shell effects can directly be observed in the spectra of the lighter nuclei.

  19. Dependence of nuclear spin singlet lifetimes on RF spin-locking power

    E-print Network

    Stephen J. DeVience; Ronald L. Walsworth; Matthew S. Rosen

    2012-01-06

    We measure the lifetime of long-lived nuclear spin singlet states as a function of the strength of the RF spin-locking field and present a simple theoretical model that agrees well with our measurements, including the low-RF-power regime. We also measure the lifetime of a long-lived coherence between singlet and triplet states that does not require a spin-locking field for preservation. Our results indicate that for many molecules, singlet states can be created using weak RF spin-locking fields: more than two orders of magnitude lower RF power than in previous studies. Our findings suggest that in many biomolecules, singlets and related states with enhanced lifetimes might be achievable in vivo with safe levels of RF power.

  20. Carbon-13 Labeling Used to Probe Cure and Degradation Reactions of High- Temperature Polymers

    NASA Technical Reports Server (NTRS)

    Meador, Mary Ann B.; Johnston, J. Christopher

    1998-01-01

    High-temperature, crosslinked polyimides are typically insoluble, intractible materials. Consequently, in these systems it has been difficult to follow high-temperature curing or long-term degradation reactions on a molecular level. Selective labeling of the polymers with carbon-13, coupled with solid nuclear magnetic resonance spectrometry (NMR), enables these reactions to be followed. We successfully employed this technique to provide insight into both curing and degradation reactions of PMR-15, a polymer matrix resin used extensively in aircraft engine applications.

  1. Probing the Dynamics of a Nuclear Spin Bath in Diamond through Time-Resolved Central Spin Magnetometry

    NASA Astrophysics Data System (ADS)

    Dréau, A.; Jamonneau, P.; Gazzano, O.; Kosen, S.; Roch, J.-F.; Maze, J. R.; Jacques, V.

    2014-09-01

    Using fast electron spin resonance spectroscopy of a single nitrogen-vacancy defect in diamond, we demonstrate real-time readout of the Overhauser field produced by its nuclear spin environment under ambient conditions. These measurements enable narrowing the Overhauser field distribution by postselection, corresponding to a conditional preparation of the nuclear spin bath. Correlations of the Overhauser field fluctuations are quantitatively inferred by analyzing the Allan deviation over consecutive measurements. This method allows us to extract the dynamics of weakly coupled nuclear spins of the reservoir.

  2. Dynamics of Overhauser Field under nuclear spin diffusion in a quantum dot

    E-print Network

    Zhe-Xuan Gong; Zhang-qi Yin; L. -M. Duan

    2009-12-22

    The coherence of electron spin can be significantly enhanced by locking the Overhauser field from nuclear spins using the nuclear spin preparation. We propose a theoretical model to calculate the long time dynamics of the Overhauser field under intrinsic nuclear spin diffusion in a quantum dot. We obtain a simplified diffusion equation that can be numerically solved and show quantitatively how the Knight shift and the electron-mediated nuclear spin flip-flop affect the nuclear spin diffusion. The results explain several recent experimental observations, where the decay time of Overhauser field is measured under different configurations, including variation of the external magnetic field, the electron spin configuration in a double dot, and the initial nuclear spin polarization rate.

  3. Investigation of the Possibility of Using Nuclear Magnetic Spin Alignment

    NASA Technical Reports Server (NTRS)

    Dent, William V., Jr.

    1998-01-01

    The goal of the program to investigate a "Gasdynamic fusion propulsion system for space exploration" is to develop a fusion propulsion system for a manned mission to the planet mars. A study using Deuterium and Tritium atoms are currently in progress. When these atoms under-go fusion, the resulting neutrons and alpha particles are emitted in random directions (isotropically). The probable direction of emission is equal for all directions, thus resulting in wasted energy, massive shielding and cooling requirements, and serious problems with the physics of achieving fusion. If the nuclear magnetic spin moments of the deuterium and tritium nuclei could be precisely aligned at the moment of fusion, the stream of emitted neutrons could be directed out the rear of the spacecraft for thrust and the alpha particles directed forward into an electromagnet ot produce electricity to continue operating the fusion engine. The following supporting topics are discussed: nuclear magnetic moments and spin precession in magnetic field, nuclear spin quantum mechanics, kinematics of nuclear reactions, and angular distribution of particles.

  4. Storing entanglement of nuclear spins via Uhrig dynamical decoupling

    SciTech Connect

    Roy, Soumya Singha; Mahesh, T. S. [Indian Institute of Science Education and Research, Pune 411008 (India); Agarwal, G. S. [Department of Physics, Oklahoma State University, Stillwater, Oklahoma 74078 (United States)

    2011-06-15

    Stroboscopic spin flips have already been shown to prolong the coherence times of quantum systems under noisy environments. Uhrig's dynamical decoupling scheme provides an optimal sequence for a quantum system interacting with a dephasing bath. Several experimental demonstrations have already verified the efficiency of such dynamical decoupling schemes in preserving single-qubit coherences. In this work we describe the experimental study of Uhrig's dynamical decoupling in preserving two-qubit entangled states using an ensemble of spin-1/2 nuclear pairs in solution state. We find that the performance of odd-order Uhrig sequences in preserving entanglement is superior to both even-order Uhrig sequences and periodic spin-flip sequences. We also find that there exists an optimal order of the Uhrig sequence in which a singlet state can be stored at high correlation for about 30 seconds.

  5. Storing entanglement of nuclear spins via Uhrig Dynamical Decoupling

    E-print Network

    Soumya Singha Roy; T. S. Mahesh; G. S. Agarwal

    2011-10-07

    Stroboscopic spin flips have already been shown to prolong the coherence times of quantum systems under noisy environments. Uhrig's dynamical decoupling scheme provides an optimal sequence for a quantum system interacting with a dephasing bath. Several experimental demonstrations have already verified the efficiency of such dynamical decoupling schemes in preserving single qubit coherences. In this work we describe the experimental study of Uhrig's dynamical decoupling in preserving two-qubit entangled states using an ensemble of spin-1/2 nuclear pairs in solution state. We find that the performance of odd-order Uhrig sequences in preserving entanglement is superior to both even-order Uhrig sequences and periodic spin-flip sequences. We also find that there exists an optimal length of the Uhrig sequence at which the decoherence time gets boosted from a few seconds to about 30 seconds.

  6. A high-precision carbon-13 shift thermometer for the temperature range 100-300 K

    PubMed

    Quast; Heubes; Dunger; Limbach

    1998-10-01

    The first carbon-13 shift thermometer for the temperature range of 100-300 K is based on the very rapid equilibration of a pair of semibullvalene valence tautomers. The temperature dependence of the equilibrium constant is reflected in strongly temperature-dependent shift differences Deltadelta between averaged signals, e.g., d(Deltadelta)/dT = 0.051 ppm K-1 at 300, 0.087 ppm K-1 at 200, and 0. 175 ppm K-1 at 110 K for the quaternary carbon atoms C2 and C6. At 37 temperatures T, which were measured with calibrated platinum resistance thermometers, shift differences Deltadelta were taken from nondecoupled carbon-13 spectra recorded from solutions of 1 in mixtures of chlorodifluoromethane and deuterated dimethyl ether without spinning. The least-squares fit of these Deltadelta vs T data to a polynomial equation of the fourth degree (Eq. [5], r2 = 0. 9999) allows the calculation of temperatures from measured shift differences with a standard deviation of 0.46 K and an estimated error of about 1 K. The heating effects of WALTZ-16 decoupling and the influence of solvents on Deltadelta are investigated. A comparison with existing NMR thermometers demonstrates the superior performance of the new carbon-13 shift thermometer with respect to precision and the accessible temperature range. Copyright 1998 Academic Press. PMID:9761699

  7. RF instrumentation and system design for coherent control of anisotropic hyperfine-coupled electron/nuclear spin qubits

    E-print Network

    Abutaleb, Mohamed Osama

    2010-01-01

    Coherent control is a fundamental challenge in quantum information processing (QIP). Our system of interest employs a local, isolated electron spin to coherently control nuclear spins. Coupled electron/nuclear spins are a ...

  8. Dynamic polarization of single nuclear spins by optical pumping of nitrogen-vacancy color centers in diamond at room temperature.

    PubMed

    Jacques, V; Neumann, P; Beck, J; Markham, M; Twitchen, D; Meijer, J; Kaiser, F; Balasubramanian, G; Jelezko, F; Wrachtrup, J

    2009-02-01

    We report a versatile method to polarize single nuclear spins in diamond, based on optical pumping of a single nitrogen-vacancy (NV) defect and mediated by a level anticrossing in its excited state. A nuclear-spin polarization higher than 98% is achieved at room temperature for the 15N nuclear spin associated with the NV center, corresponding to microK effective nuclear-spin temperature. We then show simultaneous initialization of two nuclear spins in the vicinity of a NV defect. Such robust control of nuclear-spin states is a key ingredient for further scaling up of nuclear-spin based quantum registers in diamond. PMID:19257552

  9. Manipulation of the nuclear spin ensemble in a quantum dot with chirped magnetic resonance pulses

    NASA Astrophysics Data System (ADS)

    Munsch, Mathieu; Wüst, Gunter; Kuhlmann, Andreas V.; Xue, Fei; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.; Poggio, Martino; Warburton, Richard J.

    2014-09-01

    The nuclear spins in nanostructured semiconductors play a central role in quantum applications. The nuclear spins represent a useful resource for generating local magnetic fields but nuclear spin noise represents a major source of dephasing for spin qubits. Controlling the nuclear spins enhances the resource while suppressing the noise. NMR techniques are challenging: the group III and V isotopes have large spins with widely different gyromagnetic ratios; in strained material there are large atom-dependent quadrupole shifts; and nanoscale NMR is hard to detect. We report NMR on 100,000 nuclear spins of a quantum dot using chirped radiofrequency pulses. Following polarization, we demonstrate a reversal of the nuclear spin. We can flip the nuclear spin back and forth a hundred times. We demonstrate that chirped NMR is a powerful way of determining the chemical composition, the initial nuclear spin temperatures and quadrupole frequency distributions for all the main isotopes. The key observation is a plateau in the NMR signal as a function of sweep rate: we achieve inversion at the first quantum transition for all isotopes simultaneously. These experiments represent a generic technique for manipulating nanoscale inhomogeneous nuclear spin ensembles and open the way to probe the coherence of such mesoscopic systems.

  10. Nuclear Magnetic Relaxation in METHYLENE-13 and METHYL-13 Coupled Spin Systems and Variable Angle Spinning Lineshape Analysis for Quadrupolar Nuclei with Half Integer Spins

    NASA Astrophysics Data System (ADS)

    Zheng, Zhiwen

    1992-01-01

    The carbon-13 multiplet spin-lattice relaxation in ^{13}CH_2 and ^{13}CH _3^in systems is studied in detail by various nonselective and selective pulse techniques. Simultaneous fitting of the resulting relaxation curves with various rates and initial conditions allows for the extraction of both auto- and cross-correlated dipolar spectral densities which can provide detailed information on the molecular anisotropic reorientation. In addition, the ^ {13}CH_3 coupled spin relaxation can characterize the methyl internal rotation dynamics. The cross-correlation between the dipolar and chemical shift anisotropy (CSA) interactions is found to be appreciable. Dipolar-CSA cross-correlated spectral densities introduce relaxation pathways that couple together magnetization modes with different spin inversion symmetries. Consideration of the dipolar-CSA cross-correlated spectral densities not only improves the accuracy of the measurement of dipolar spectral densities but also allows for the determination of the dipolar-CSA cross-correlated spectral densities themselves, providing a new measure of the anisotropy of the shielding tensor. NMR spectroscopy of quadrupolar nuclei in solids generally yields broad lines even when magic angle spinning is applied. Broadening of the central transition of quadrupolar nuclei with half integer spins is caused by the anisotropy of the second order quadrupolar interaction. A straightforward approach is presented that combines average Hamiltonian theory and a numerical solution of a classical banded matrix describing the equation of motion for a quadrupolar nucleus under variable angle sample spinning conditions. At either of two fourth rank magic angles, a simple three parameter lineshape is obtained, and the three breakpoints are related directly to the quadrupolar constant and its asymmetry parameter. The banded matrix method used in the simulations is computationally much more efficient than the standard method using Bessel functions.

  11. Solid effect in magic angle spinning dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Corzilius, Björn; Smith, Albert A.; Griffin, Robert G.

    2012-08-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ? _0 ^{ - 2} field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ? = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of 1H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear 1H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect.

  12. Solid effect in magic angle spinning dynamic nuclear polarization.

    PubMed

    Corzilius, Björn; Smith, Albert A; Griffin, Robert G

    2012-08-01

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic field DNP experiments because SE enhancements display an ?(0)(-2) field dependence. In particular, for nominally forbidden zero and double quantum SE transitions to be partially allowed, it is necessary for mixing of adjacent nuclear spin states to occur, and this leads to the observed field dependence. However, recently we have improved our instrumentation and report here an enhancement of ? = 91 obtained with the organic radical trityl (OX063) in magic angle spinning experiments performed at 5 T and 80 K. This is a factor of 6-7 higher than previous values in the literature under similar conditions. Because the solid effect depends strongly on the microwave field strength, we attribute this large enhancement to larger microwave field strengths inside the sample volume, achieved with more efficient coupling of the gyrotron to the sample chamber. In addition, we develop a theoretical model to explain the dependence of the buildup rate of enhanced nuclear polarization and the steady-state enhancement on the microwave power. Buildup times and enhancements were measured as a function of (1)H concentration for both trityl and Gd-DOTA. Comparison of the results indicates that for trityl the initial polarization step is the slower, rate-determining step. However, for Gd-DOTA the spread of nuclear polarization via homonuclear (1)H spin diffusion is rate-limiting. Finally, we discuss the applicability of the solid effect at fields > 5 T and the requirements to address the unfavorable field dependence of the solid effect. PMID:22894339

  13. Nuclear Spin Maser at Highly Stabilized Low Magnetic Field and Search for Atomic EDM

    SciTech Connect

    Yoshimi, A. [RIKEN Nishina Center, Hirosawa 2-1, Wako, Saitama 351-0198 (Japan); Asahi, K.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Tsuchiya, M.; Kagami, S. [Department of Physics, Tokyo Institute of Technology, Oh-okayama 2-12-1, Meguro, Tokyo 152-8551 (Japan)

    2009-08-04

    A nuclear spin maser is operated at a low static field through an active feedback scheme based on an optical nuclear spin detection and succeeding spin control by a transverse field application. The frequency stability of this optical-coupling spin maser is improved by installation of a low-noise current source for a solenoid magnet producing a static magnetic field in the maser operation. Experimental devices for application of the maser to EDM experiment are being developed.

  14. Hyperfine Interactions 127 (2000) 395398 395 Manifestation of nuclear spin-dependent P-odd

    E-print Network

    Kozlov, Mikhail G

    Hyperfine Interactions 127 (2000) 395­398 395 Manifestation of nuclear spin-dependent P-odd Nuclear Physics Institute, 188350 Gatchina, Leningrad district, Russia E-mail: porsev@thd.pnpi.spb.ru P-odd effects caused by the nuclear spin-dependent electron­nucleon interaction are con- sidered. P-odd

  15. Nuclear Hydrogen for Peak Electricity Production and Spinning Reserve

    SciTech Connect

    Forsberg, C.W.

    2005-01-20

    Nuclear energy can be used to produce hydrogen. The key strategic question is this: ''What are the early markets for nuclear hydrogen?'' The answer determines (1) whether there are incentives to implement nuclear hydrogen technology today or whether the development of such a technology could be delayed by decades until a hydrogen economy has evolved, (2) the industrial partners required to develop such a technology, and (3) the technological requirements for the hydrogen production system (rate of production, steady-state or variable production, hydrogen purity, etc.). Understanding ''early'' markets for any new product is difficult because the customer may not even recognize that the product could exist. This study is an initial examination of how nuclear hydrogen could be used in two interconnected early markets: the production of electricity for peak and intermediate electrical loads and spinning reserve for the electrical grid. The study is intended to provide an initial description that can then be used to consult with potential customers (utilities, the Electric Power Research Institute, etc.) to better determine the potential real-world viability of this early market for nuclear hydrogen and provide the starting point for a more definitive assessment of the concept. If this set of applications is economically viable, it offers several unique advantages: (1) the market is approximately equivalent in size to the existing nuclear electric enterprise in the United States, (2) the entire market is within the utility industry and does not require development of an external market for hydrogen or a significant hydrogen infrastructure beyond the utility site, (3) the technology and scale match those of nuclear hydrogen production, (4) the market exists today, and (5) the market is sufficient in size to justify development of nuclear hydrogen production techniques independent of the development of any other market for hydrogen. These characteristics make it an ideal early market for nuclear hydrogen.

  16. Suppression of nuclear spin bath fluctuations in self-assembled quantum dots induced by inhomogeneous strain

    NASA Astrophysics Data System (ADS)

    Chekhovich, E. A.; Hopkinson, M.; Skolnick, M. S.; Tartakovskii, A. I.

    2015-02-01

    Interaction with nuclear spins leads to decoherence and information loss in solid-state electron-spin qubits. One particular, ineradicable source of electron decoherence arises from decoherence of the nuclear spin bath, driven by nuclear–nuclear dipolar interactions. Owing to its many-body nature nuclear decoherence is difficult to predict, especially for an important class of strained nanostructures where nuclear quadrupolar effects have a significant but largely unknown impact. Here, we report direct measurement of nuclear spin bath coherence in individual self-assembled InGaAs/GaAs quantum dots: spin-echo coherence times in the range 1.2–4.5?ms are found. Based on these values, we demonstrate that strain-induced quadrupolar interactions make nuclear spin fluctuations much slower compared with lattice-matched GaAs/AlGaAs structures. Our findings demonstrate that quadrupolar effects can potentially be used to engineer optically active III-V semiconductor spin-qubits with a nearly noise-free nuclear spin bath, previously achievable only in nuclear spin-0 semiconductors, where qubit network interconnection and scaling are challenging.

  17. Suppression of nuclear spin bath fluctuations in self-assembled quantum dots induced by inhomogeneous strain

    PubMed Central

    Chekhovich, E.A.; Hopkinson, M.; Skolnick, M.S.; Tartakovskii, A.I.

    2015-01-01

    Interaction with nuclear spins leads to decoherence and information loss in solid-state electron-spin qubits. One particular, ineradicable source of electron decoherence arises from decoherence of the nuclear spin bath, driven by nuclear–nuclear dipolar interactions. Owing to its many-body nature nuclear decoherence is difficult to predict, especially for an important class of strained nanostructures where nuclear quadrupolar effects have a significant but largely unknown impact. Here, we report direct measurement of nuclear spin bath coherence in individual self-assembled InGaAs/GaAs quantum dots: spin-echo coherence times in the range 1.2–4.5?ms are found. Based on these values, we demonstrate that strain-induced quadrupolar interactions make nuclear spin fluctuations much slower compared with lattice-matched GaAs/AlGaAs structures. Our findings demonstrate that quadrupolar effects can potentially be used to engineer optically active III-V semiconductor spin-qubits with a nearly noise-free nuclear spin bath, previously achievable only in nuclear spin-0 semiconductors, where qubit network interconnection and scaling are challenging. PMID:25704639

  18. Stable Three-Axis Nuclear Spin Gyroscope in Diamond

    E-print Network

    Ajoy, Ashok

    2012-01-01

    We propose a sensitive and stable three-axis gyroscope in diamond. We achieve high sensitivity by exploiting the long coherence time of the N14 nuclear spin associated with the Nitrogen-Vacancy center in diamond, and the efficient polarization and measurement of its electronic spin. While the gyroscope is based on a simple Ramsey interferometry scheme, we use coherent control of the quantum sensor to improve its coherence time as well as its robustness against long-time drifts, thus achieving a very robust device with a resolution of 0.5mdeg/s/(Hz mm^3)^(1/2). In addition, we exploit the four axes of delocalization of the Nitrogen-Vacancy center to measure not only the rate of rotation, but also its direction, thus obtaining a compact three-axis gyroscope.

  19. Stable Three-Axis Nuclear Spin Gyroscope in Diamond

    E-print Network

    Ashok Ajoy; Paola Cappellaro

    2012-05-07

    We propose a sensitive and stable three-axis gyroscope in diamond. We achieve high sensitivity by exploiting the long coherence time of the N14 nuclear spin associated with the Nitrogen-Vacancy center in diamond, and the efficient polarization and measurement of its electronic spin. While the gyroscope is based on a simple Ramsey interferometry scheme, we use coherent control of the quantum sensor to improve its coherence time as well as its robustness against long-time drifts, thus achieving a very robust device with a resolution of 0.5mdeg/s/(Hz mm^3)^(1/2). In addition, we exploit the four axes of delocalization of the Nitrogen-Vacancy center to measure not only the rate of rotation, but also its direction, thus obtaining a compact three-axis gyroscope.

  20. Nuclear Magnetic Resonance (NMR) This technique observes signals from nuclear spins

    E-print Network

    Chen, Yang-Yuan

    magnetic moment () The Bohr model of H atom electron Nucleus I I = n I An intrinsic property of the nucleus Why & how to observe nuclear spins? Can be though of as a strange tiny magnet () #12;Timeline I 1946) 1960s: Solid state NMR ­ Waugh NMR imaging was demonstrated 1975: Fourier Imaging ­ R. Ernst Timeline

  1. Nuclear spin conversion of water inside fullerene cages detected by low-temperature nuclear magnetic resonance

    SciTech Connect

    Mamone, Salvatore, E-mail: s.mamone@soton.ac.uk; Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Denning, Mark; Carravetta, Marina; Whitby, Richard J.; Levitt, Malcolm H., E-mail: mhl@soton.ac.uk [School of Chemistry, University of Southampton, Southampton SO17 1BJ (United Kingdom); Lei, Xuegong; Li, Yongjun [Department of Chemistry, Columbia University, New York, New York 10027 (United States)] [Department of Chemistry, Columbia University, New York, New York 10027 (United States); Goh, Kelvin; Horsewill, Anthony J. [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)] [School of Physics and Astronomy, University of Nottingham, Nottingham NG7 2RD (United Kingdom)

    2014-05-21

    The water-endofullerene H{sub 2}O@C{sub 60} provides a unique chemical system in which freely rotating water molecules are confined inside homogeneous and symmetrical carbon cages. The spin conversion between the ortho and para species of the endohedral H{sub 2}O was studied in the solid phase by low-temperature nuclear magnetic resonance. The experimental data are consistent with a second-order kinetics, indicating a bimolecular spin conversion process. Numerical simulations suggest the simultaneous presence of a spin diffusion process allowing neighbouring ortho and para molecules to exchange their angular momenta. Cross-polarization experiments found no evidence that the spin conversion of the endohedral H{sub 2}O molecules is catalysed by {sup 13}C nuclei present in the cages.

  2. Estimation of optical chemical shift in nuclear spin optical rotation

    NASA Astrophysics Data System (ADS)

    Chen, Fang; Yao, Guo-hua; He, Tian-jing; Chen, Dong-ming; Liu, Fan-chen

    2014-05-01

    A recently proposed optical chemical shift in nuclear spin optical rotation (NSOR) is studied by theoretical comparison of NSOR magnitude between chemically non-equivalent or different element nuclei in the same molecule. Theoretical expressions of the ratio R between their NSOR magnitudes are derived by using a known semi-empirical formula of NSOR. Taking methanol, tri-ethyl-phosphite and 2-methyl-benzothiazole as examples, the ratios R are calculated and the results approximately agree with the experiments. Based on those, the important influence factors on R and chemical distinction by NSOR are discussed.

  3. Efficient room-temperature nuclear spin hyperpolarization of a defect atom in a semiconductor.

    PubMed

    Puttisong, Y; Wang, X J; Buyanova, I A; Geelhaar, L; Riechert, H; Ptak, A J; Tu, C W; Chen, W M

    2013-01-01

    Nuclear spin hyperpolarization is essential to future solid-state quantum computation using nuclear spin qubits and in highly sensitive magnetic resonance imaging. Though efficient dynamic nuclear polarization in semiconductors has been demonstrated at low temperatures for decades, its realization at room temperature is largely lacking. Here we demonstrate that a combined effect of efficient spin-dependent recombination and hyperfine coupling can facilitate strong dynamic nuclear polarization of a defect atom in a semiconductor at room temperature. We provide direct evidence that a sizeable nuclear field (~150 Gauss) and nuclear spin polarization (~15%) sensed by conduction electrons in GaNAs originates from dynamic nuclear polarization of a Ga interstitial defect. We further show that the dynamic nuclear polarization process is remarkably fast and is completed in <5 ?s at room temperature. The proposed new concept could pave a way to overcome a major obstacle in achieving strong dynamic nuclear polarization at room temperature, desirable for practical device applications. PMID:23612292

  4. NMR response of nuclear-spin helix in quantum wires with hyperfine and spin-orbit interaction

    NASA Astrophysics Data System (ADS)

    Stano, Peter; Loss, Daniel

    2014-11-01

    We calculate the nuclear magnetic resonance (NMR) response of a quantum wire where at low temperature a self-sustained electron-nuclear spin order is created. Our model includes the electron mediated Ruderman-Kittel-Kasuya-Yosida (RKKY) exchange, electron spin-orbit interactions, nuclear dipolar interactions, and the static and oscillating NMR fields, all of which play an essential role. The paramagnet to helimagnet transition in the nuclear system is reflected in an unusual response: it absorbs at a frequency given by the internal RKKY exchange field, rather than the external static field, whereas the latter leads to a splitting of the resonance peak.

  5. Dynamics of entanglement of two electron spins interacting with nuclear spin baths in quantum dots

    E-print Network

    Igor Bragar; ?ukasz Cywi?ski

    2014-11-23

    We study the dynamics of entanglement of two electron spins in two quantum dots, in which each electron is interacting with its nuclear spin environment. Focusing on the case of uncoupled dots, and starting from either Bell or Werner states of two qubits, we calculate the decay of entanglement due to hyperfine interaction with the nuclei. We mostly focus on the regime of magnetic fields in which the bath-induced electron spin flips play a role, for example their presence leads to appearance of entanglement sudden death at finite time for two qubits initialized in a Bell state. For these fields the intra-bath dipolar interactions and inhomogeneity of hyperfine couplings are irrelevant on timescales of coherence (and entanglement) decay, and most of the presented calculations are performed using the uniform-coupling approximation to the exact hyperfine Hamiltonian. We provide a comprehensive overview of entanglement decay in this regime, considering both free evolution of the qubits, and an echo protocol with simultaneous application of $\\pi$ pulses to the two spins. All the currently experimentally relevant bath states are considered: the thermal state, narrowed states (characterized by diminished uncertainty of one of the components of the Overhauser field) for two uncorrelated baths, and a correlated narrowed state with well-defined value of the $z$ component of the Overhauser field interdot gradient. While we mostly use concurrence to quantify the amount of entanglement in a mixed state of the two electron spins, we also discuss the predicted behavior of currently experimentally relevant entanglement witnesses, and in particular we give results for quantum teleportation fidelity using a partially disentangled state as a resource.

  6. Collisionally assisted, highly selective laser isotope separation of carbon-13

    Microsoft Academic Search

    M. Polianski; O. V. Boyarkin; T. R. Rizzo

    2004-01-01

    We have further developed our recently reported two-laser technique for highly selective molecular isotope separation of carbon-13 [Boyarkin, Kowalczyk, and Rizzo, J. Chem. Phys. 118, 93 (2003)] with the objective of increasing the yield. An essential feature of this approach in its original conception is the significant increase of isotopic selectivity that occurs through collisions during the time between the

  7. Nuclear Spin Orientation Dependence of Magnetoconductance: A New Method for Measuring the Spin of Charged Excitations in the QHE

    SciTech Connect

    Bowers, C.R.; Reno, J.L.; Simmons, J.A.; Vitkalov, S.A.

    1998-12-01

    A new method for measuring the spin of the electrically charged ground state excitations m the Q$j~j quantum Hall effect ia proposed and demonstmted for the tirst time in GaAs/AIGaAs nndtiquantum wells. The method is &sed on the nuclear spin orientation dependence of" the 2D dc conductivity y in the quantum Hall regime due to the nuclear hyperfine interaction. As a demonstration of this method the spin of the electrically charged excitations of the ground state is determined at filling factor v = 1.

  8. Carbon-13 nuclear magnetic resonance studies of glycolysis in protozoa

    E-print Network

    Rhoades, Teresa Ann

    1986-01-01

    , I. Scott. A ht gty ty 1 1 tt 1 t A E g1 ~gati h h studied by C NMR spectroscopy. The fate of C label was analyzed 13 13 in cell extracts and the glycolytic end products succinate, malate, acetate, and mannitol identified. Pathways of succinate... observed. ACKNOWLEDGMENTS I wish to express my gratitude to Dr. Neil Mackenzie for his gui- dance, patience, and support throughout this work. My sincere appre- ciation goes to Dr. Paul Fagerness for sharing his NMR expertise and to Dr. Ian l31agbrough...

  9. Experimental demonstration of stimulated polarization wave in a chain of nuclear spins

    E-print Network

    Jae-Seung Lee; Travis Adams; A. K. Khitrin

    2007-01-10

    A stimulated wave of polarization, which implements a simple mechanism of quantum amplification, is experimentally demonstrated in a chain of four J-coupled nuclear spins, irradiated by a weak radio-frequency transverse field. The "quantum domino" dynamics, a wave of flipped spins triggered by a flip of the first spin, has been observed in fully $^{13}$C-labeled sodium butyrate.

  10. Nuclear Polarization and Impurity-State Spin Relaxation Processes in Silicon

    Microsoft Academic Search

    David Pines; John Bardeen; Charles P. Slichter

    1957-01-01

    Two proposals are made for producing nuclear polarization by a transient analog of the Overhauser effect in the impurity-state electron spin resonance in silicon. The success of the proposal polarization schemes requires that the electron spin relaxation process in which the impurity nucleus and the electron simultaneously flip their spins be faster than those relaxation processes in which an electron

  11. Nuclear spin structure in dark matter search: The finite momentum transfer limit

    E-print Network

    V. A. Bednyakov; F. Simkovic

    2006-08-09

    Spin-dependent elastic scattering of weakly interacting massive dark matter particles (WIMP) off nuclei is reviewed. All available, within different nuclear models, structure functions S(q) for finite momentum transfer (q>0) are presented. These functions describe the recoil energy dependence of the differential event rate due to the spin-dependent WIMP-nucleon interactions. This paper, together with the previous paper ``Nuclear spin structure in dark matter search: The zero momentum transfer limit'', completes our review of the nuclear spin structure calculations involved in the problem of direct dark matter search.

  12. Nuclear spin structure in dark matter search: The finite momentum transfer limit

    NASA Astrophysics Data System (ADS)

    Bednyakov, V. A.; Šimkovic, F.

    2006-12-01

    Spin-dependent elastic scattering of weakly interacting massive dark matter particles (WIMP) off nuclei is reviewed. All available, within different nuclear models, structure functions S(q) for finite momentum transfer (q > 0) are presented. These functions describe the recoil energy dependence of the differential event rate due to the spin-dependent WIMP-nucleon interactions. This paper, together with the previous paper “Nuclear Spin Structure in Dark Matter Search: The Zero Momentum Transfer Limit,” completes our review of the nuclear spin structure calculations involved in the problem of direct dark matter search.

  13. Nuclear spin selection rules in chemical reactions by angular momentum algebra

    E-print Network

    Oka, Takeshi

    Nuclear spin selection rules in chemical reactions by angular momentum algebra Takeshi Oka by Quack using molecular symmetry group are derived by using angu- lar momentum algebra. Instead: Selection rules; Nuclear spin modifications; Angular momentum algebra; Ion-neutral reactions; Molecular ions

  14. Nuclear spin-lattice relaxation in the sodium anion, Na -

    NASA Astrophysics Data System (ADS)

    Holton, Dolores M.; Ellaboudy, Ahmed; Pyper, Nicholas C.; Edwards, Peter P.

    1986-02-01

    We report direct measurements of nuclear spin-lattice relaxation times (T1n) for the sodium anion, Na-, in solutions containing both sodium and a heavier alkali metal in 1,4,7,10-tetraoxacyclododecane (12-crown-4, 12C4). Nuclear spin-lattice relaxation in Na- is found to be essentially independent of the alkali counterion and to depend only weakly upon the concentration of sodide ion in solution. The temperature dependence of T1n for Na- was used to determine an activation energy for the processes responsible for spin relaxation. The results are consistent with a dominant, but very inefficient, quadrupolar relaxation mechanism which involves the modulation of the electric field gradient at Na- via the reorientation and/or translational motion of surrounding 12C4 molecules in the liquid. Furthermore, we find that solvation of Na- in 12C4 as well described by a model in which there is neither preferential orientation of 12C4 molecules nor a clearly identifiable first solvation shell around the sodide ion. Consistent with this description, the activation energies for the processes responsible for spin-lattice relaxation in Na- are close to those observed for the processes causing 1H and 13C relaxation in the neat liquid crown. We outline two methods, which take into account electron-electron correlation effects, for determining the Sternheimer antishielding factor ?2 for the sodium anion. The most realistic estimate for ?2 (-14.98) is used to calculate the NMR linewidth for Na- when it is associated with an uncomplexed (unsolvated) sodium cation and also in the contact and solvent-separated Na+-Na- ion pairs. A rms value of 0.03 MHz for the quadrupole coupling constant (e2qQ/?) of Na- in 12C4 solutions is deduced. We conclude that Na- in these solutions suffers only minor perturbations on its gas-phase electronic structure; neither does it exist as part of a contact or solvent-separated ion pair. It appears that the sodide ion represents the closest realization of a gas-like ionic moiety in solution.

  15. A 3D-Printed High Power Nuclear Spin Polarizer

    PubMed Central

    Nikolaou, Panayiotis; Coffey, Aaron M.; Walkup, Laura L.; Gust, Brogan M.; LaPierre, Cristen D.; Koehnemann, Edward; Barlow, Michael J.; Rosen, Matthew S.; Goodson, Boyd M.; Chekmenev, Eduard Y.

    2015-01-01

    Three-dimensional printing with high-temperature plastic is used to enable spin exchange optical pumping (SEOP) and hyperpolarization of xenon-129 gas. The use of 3D printed structures increases the simplicity of integration of the following key components with a variable temperature SEOP probe: (i) in situ NMR circuit operating at 84 kHz (Larmor frequencies of 129Xe and 1H nuclear spins), (ii) <0.3 nm narrowed 200 W laser source, (iii) in situ high-resolution near-IR spectroscopy, (iv) thermoelectric temperature control, (v) retroreflection optics, and (vi) optomechanical alignment system. The rapid prototyping endowed by 3D printing dramatically reduces production time and expenses while allowing reproducibility and integration of “off-the-shelf” components and enables the concept of printing on demand. The utility of this SEOP setup is demonstrated here to obtain near-unity 129Xe polarization values in a 0.5 L optical pumping cell, including ~74 ± 7% at 1000 Torr xenon partial pressure, a record value at such high Xe density. Values for the 129Xe polarization exponential build-up rate [(3.63 ± 0.15) × 10?2 min?1] and in-cell 129Xe spin?lattice relaxation time (T1 = 2.19 ± 0.06 h) for 1000 Torr Xe were in excellent agreement with the ratio of the gas-phase polarizations for 129Xe and Rb (PRb ~ 96%). Hyperpolarization-enhanced 129Xe gas imaging was demonstrated with a spherical phantom following automated gas transfer from the polarizer. Taken together, these results support the development of a wide range of chemical, biochemical, material science, and biomedical applications. PMID:24400919

  16. Frequency selective detection of nuclear quadrupole resonance (NQR) spin echoes

    NASA Astrophysics Data System (ADS)

    Somasundaram, Samuel D.; Jakobsson, Andreas; Smith, John A. S.; Althoefer, Kaspar A.

    2006-05-01

    Nuclear Quadrupole Resonance (NQR) is a radio frequency (RF) technique that can be used to detect the presence of quadrupolar nuclei, such as the 14N nucleus prevalent in many explosives and narcotics. The technique has been hampered by low signal-to-noise ratios and is further aggravated by the presence of RF interference (RFI). To ensure accurate detection, proposed detectors should exploit the rich form of the NQR signal. Furthermore, the detectors should also be robust to any remaining residual interference, left after suitable RFI mitigation has been employed. In this paper, we propose a new NQR data model, particularly for the realistic case where multiple pulse sequences are used to generate trains of spin echoes. Furthermore, we refine two recently proposed approximative maximum likelihood (AML) detectors, enabling the algorithm to optimally exploit the data model of the entire echo train and also incorporate knowledge of the temperature dependent spin-echo decay time. The AML-based detectors ensure accurate detection and robustness against residual RFI, even when the temperature of the sample is not precisely known, by exploiting the dependencies of the NQR resonant lines on temperature. Further robustness against residual interference is gained as the proposed detector is frequency selective; exploiting only those regions of the spectrum where the NQR signal is expected. Extensive numerical evaluations based on both simulated and measured NQR data indicate that the proposed Frequency selective Echo Train AML (FETAML) detector offers a significant improvement as compared to other existing detectors.

  17. Efficient, highly selective laser isotope separation of carbon-13

    Microsoft Academic Search

    M. N. Polianski; T. R. Rizzo; O. V. Boyarkin

    2006-01-01

    We recently demonstrated an original approach to highly selective laser isotope separation of carbon-13 that employs vibrational overtone pre-excitation of CF3H together with infrared multiphoton dissociation [O.V. Boyarkin, M. Kowalczyk, T.R. Rizzo, J. Chem. Phys. 118, 93 (2003)]. The practical implementation of this approach was complicated by the long absorption path length needed for the overtone excitation laser beam. In

  18. Ultrafast control of nuclear spins using only microwave pulses: towards switchable solid-state quantum gates

    E-print Network

    George Mitrikas; Yiannis Sanakis; Georgios Papavassiliou

    2009-10-13

    We demonstrate the control of the alpha-proton nuclear spin, I=1/2, coupled to the stable radical CH(COOH)2, S=1/2, in a gamma-irradiated malonic acid single crystal using only microwave pulses. We show that, depending on the state of the electron spin mS=+/-1/2, the nuclear spin can be locked in a desired state or oscillate between mI=+1/2 and mI=-1/2 on the nanosecond time scale. This approach provides a fast and efficient way of controlling nuclear spin qubits and also enables the design of switchable spin-based quantum gates by addressing only the electron spin.

  19. Separating subspectra from cross-polarization magic-angle spinning nuclear magnetic resonance spectra by proton spin relaxation editing

    Microsoft Academic Search

    Roger H. Newman; Leo M. Condron

    1995-01-01

    Differences in proton spin relaxation time constants can be exploited to edit cross-polarization magic-angle spinning nuclear magnetic resonance (CP-MAS NMR) spectra of heterogeneous mixtures of different types of organic matter. This paper describes an extension of the editing procedure from two-component to three-component mixtures. Clean separation of 13C NMR subspectra was achieved for three synthetic polymers mixed as powders. Applying

  20. Spin interference in the spin density matrix of a compound nucleus in reactions of nuclear fission by cold polarized neutrons

    Microsoft Academic Search

    S. G. Kadmensky; L. V. Titova; V. E. Bunakov

    2011-01-01

    Spin density matrices of neutron resonance states of a compound nucleus formed in the reaction of capture of a polarized neutron\\u000a by a non-oriented target nucleus for different directions of neutron polarization vector are constructed within the quantum\\u000a fission theory. The obtained spin matrices are used to calculate T-odd asymmetries in differential cross sections of ternary\\u000a nuclear fission with the

  1. Phase-Sensitive Probes of Nuclear Polarization in Spin-Blockaded Quantum Dots

    NASA Astrophysics Data System (ADS)

    Rudner, Mark; Neder, Izhar; Levitov, Leonid; Halperin, Bertrand

    2010-03-01

    Semiconducting quantum dots provide a platform for investigating the quantum many-body dynamics of coupled electron and nuclear spins. The phenomenon of spin blockade, wherein the Pauli exclusion principle requires electrons to flip their spins in order to pass through the system [1], is an invaluable tool in this pursuit. We describe a new regime of coupled electron and nuclear spin dynamics in spin-blockaded quantum dots where the hyperfine coupling to nuclear spins competes with a purely electronic spin-flip mechanism, such as the spin-orbit interaction or coupling to an inhomogeneous Zeeman field [M. S. Rudner et al., arXiv:0909.0060]. We show that the long-lived coherence of the nuclear spin bath plays a crucial role and leads to a range of new surprising phenomena. In particular, a purely electrical detection of coherent nuclear precession can be realized. Recent results of Foletti et al. [arXiv:0801.3613] suggest that this interesting new regime is now within experimental reach. [1] K. Ono et al. Science 297, 1313 (2002).

  2. Atomic-Scale Nuclear Spin Imaging Using Quantum-Assisted Sensors in Diamond

    NASA Astrophysics Data System (ADS)

    Ajoy, A.; Bissbort, U.; Lukin, M. D.; Walsworth, R. L.; Cappellaro, P.

    2015-01-01

    Nuclear spin imaging at the atomic level is essential for the understanding of fundamental biological phenomena and for applications such as drug discovery. The advent of novel nanoscale sensors promises to achieve the long-standing goal of single-protein, high spatial-resolution structure determination under ambient conditions. In particular, quantum sensors based on the spin-dependent photoluminescence of nitrogen-vacancy (NV) centers in diamond have recently been used to detect nanoscale ensembles of external nuclear spins. While NV sensitivity is approaching single-spin levels, extracting relevant information from a very complex structure is a further challenge since it requires not only the ability to sense the magnetic field of an isolated nuclear spin but also to achieve atomic-scale spatial resolution. Here, we propose a method that, by exploiting the coupling of the NV center to an intrinsic quantum memory associated with the nitrogen nuclear spin, can reach a tenfold improvement in spatial resolution, down to atomic scales. The spatial resolution enhancement is achieved through coherent control of the sensor spin, which creates a dynamic frequency filter selecting only a few nuclear spins at a time. We propose and analyze a protocol that would allow not only sensing individual spins in a complex biomolecule, but also unraveling couplings among them, thus elucidating local characteristics of the molecule structure.

  3. Atomic-scale nuclear spin imaging using quantum-assisted sensors in diamond

    E-print Network

    Ashok Ajoy; Ulf Bissbort; Mikhail D. Lukin; Ronald L. Walsworth; Paola Cappellaro

    2014-07-11

    Nuclear spin imaging at the atomic level is essential for the understanding of fundamental biological phenomena and for applications such as drug discovery. The advent of novel nano-scale sensors has given hope of achieving the long-standing goal of single-protein, high spatial-resolution structure determination in their natural environment and ambient conditions. In particular, quantum sensors based on the spin-dependent photoluminescence of Nitrogen Vacancy (NV) centers in diamond have recently been used to detect nanoscale ensembles of external nuclear spins. While NV sensitivity is approaching single-spin levels, extracting relevant information from a very complex structure is a further challenge, since it requires not only the ability to sense the magnetic field of an isolated nuclear spin, but also to achieve atomic-scale spatial resolution. Here we propose a method that, by exploiting the coupling of the NV center to an intrinsic quantum memory associated with the Nitrogen nuclear spin, can reach a tenfold improvement in spatial resolution, down to atomic scales. The spatial resolution enhancement is achieved through coherent control of the sensor spin, which creates a dynamic frequency filter selecting only a few nuclear spins at a time. We propose and analyze a protocol that would allow not only sensing individual spins in a complex biomolecule, but also unraveling couplings among them, thus elucidating local characteristics of the molecule structure.

  4. Nuclear Spin Cooling Using Overhauser-Field Selective Coherent Population Trapping

    NASA Astrophysics Data System (ADS)

    Issler, M.; Kessler, E. M.; Giedke, G.; Yelin, S.; Cirac, I.; Lukin, M. D.; Imamoglu, A.

    2010-12-01

    We show that a quantum interference effect in optical absorption from two electronic spin states of a solid-state emitter can be used to prepare the surrounding environment of nuclear spins in well-defined states, thereby suppressing electronic spin dephasing. The coupled electron-nuclei system evolves into a coherent population trapping state by optical-excitation-induced nuclear-spin diffusion for a broad range of initial optical detunings. The spectroscopic signature of this evolution where the single-electron strongly modifies its environment is a drastic broadening of the dark resonance in optical absorption experiments. The large difference in electronic and nuclear time scales allows us to verify the preparation of nuclear spins in the desired state.

  5. Energy levels and decoherence properties of single electron and nuclear spins in a defect center in diamond

    E-print Network

    I. Popa; T. Gaebel; M. Domhan; C. Wittmann; F. Jelezko; J. Wrachtrup

    2004-09-12

    The coherent behavior of the single electron and single nuclear spins of a defect center in diamond and a 13C nucleus in its vicinity, respectively, are investigated. The energy levels associated with the hyperfine coupling of the electron spin of the defect center to the 13C nuclear spin are analyzed. Methods of magnetic resonance together with optical readout of single defect centers have been applied in order to observe the coherent dynamics of the electron and nuclear spins. Long coherence times, in the order of microseconds for electron spins and tens of microseconds for nuclear spins, recommend the studied system as a good experimental approach for implementing a 2-qubit gate.

  6. Boundary between the thermal and statistical polarization regimes in a nuclear spin ensemble

    SciTech Connect

    Herzog, B. E.; Cadeddu, D.; Xue, F.; Peddibhotla, P.; Poggio, M., E-mail: martino.poggio@unibas.ch [Department of Physics, University of Basel, Klingelbergstrasse 82, 4056 Basel (Switzerland)

    2014-07-28

    As the number of spins in an ensemble is reduced, the statistical fluctuations in its polarization eventually exceed the mean thermal polarization. This transition has now been surpassed in a number of recent nuclear magnetic resonance experiments, which achieve nanometer-scale detection volumes. Here, we measure nanometer-scale ensembles of nuclear spins in a KPF{sub 6} sample using magnetic resonance force microscopy. In particular, we investigate the transition between regimes dominated by thermal and statistical nuclear polarization. The ratio between the two types of polarization provides a measure of the number of spins in the detected ensemble.

  7. Dynamic polarization of single nuclear spins by optical pumping of NV color centers in diamond at room temperature

    E-print Network

    V. Jacques; P. Neumann; J. Beck; M. Markham; D. Twitchen; J. Meijer; F. Kaiser; G. Balasubramanian; F. Jelezko; J. Wrachtrup

    2009-02-10

    We report a versatile method to efficiently polarize single nuclear spins in diamond, which is based on optical pumping of a single NV color center and mediated by a level-anti crossing in its excited state. A nuclear spin polarization higher than 98% is achieved at room temperature for the 15N nuclear spin associated to the NV center, corresponding to $\\mu$K effective nuclear spin temperature. We then show simultaneous deterministic initialization of two nuclear spins (13C and 15N) in close vicinity to a NV defect. Such robust control of nuclear spin states is a key ingredient for further scaling up of nuclear-spin based quantum registers in diamond.

  8. Conditional control of donor nuclear spins in silicon using Stark shifts

    E-print Network

    Gary Wolfowicz; Matias Urdampilleta; Mike L. W. Thewalt; Helge Riemann; Nikolai V. Abrosimov; Peter Becker; Hans-Joachim Pohl; John J. L. Morton

    2014-05-28

    Electric fields can be used to tune donor spins in silicon using the Stark shift, whereby the donor electron wave function is displaced by an electric field, modifying the hyperfine coupling between the electron spin and the donor nuclear spin. We present a technique based on dynamic decoupling of the electron spin to accurately determine the Stark shift, and illustrate this using antimony donors in isotopically purified silicon-28. We then demonstrate two different methods to use a DC electric field combined with an applied resonant radio-frequency (RF) field to conditionally control donor nuclear spins. The first method combines an electric-field induced conditional phase gate with standard RF pulses, and the second one simply detunes the spins off-resonance. Finally, we consider different strategies to reduce the effect of electric field inhomogeneities and obtain above 90% process fidelities.

  9. Accessing long-lived nuclear singlet states between chemically equivalent spins without breaking symmetry

    PubMed Central

    Feng, Yesu; Davis, Ryan M.; Warren, Warren S.

    2013-01-01

    Long-lived nuclear spin states could greatly enhance the applicability of hyperpolarized nuclear magnetic resonance. Using singlet states between inequivalent spin pairs has been shown to extend the signal lifetime by more than an order of magnitude compared to the spin lattice relaxation time (T1), but they have to be prevented from evolving into other states. In the most interesting case the singlet is between chemically equivalent spins, as it can then be inherently an eigenstate. However this presents major challenges in the conversion from bulk magnetization to singlet. In the only case demonstrated so far, a reversible chemical reaction to break symmetry was required. Here we present a pulse sequence technique that interconverts between singlet spin order and bulk magnetization without breaking the symmetry of the spin system. This technique is independent of field strength and is applicable to a broad range of molecules. PMID:23505397

  10. Sensitivity of nuclear-quadrupole double-resonance detection of half-integer spin nuclei.

    PubMed

    Seliger, J; Zagar, V

    2008-10-01

    The sensitivity of the Slusher and Hahn's nuclear quadrupole double resonance technique is calculated in general for an arbitrary nuclear spin S of the quadrupole nuclei and for an arbitrary asymmetry parameter eta of the electric field gradient tensor. The nuclear spin S=5/2 ((17)O, (25)Mg, ...) is treated in details. The influence of the cross-relaxation rate between the quadrupole nuclei and the abundant spin system on the sensitivity of double resonance is discussed. The results of the theoretical analysis are applied in the analysis of the (1)H-(17)O nuclear quadrupole double resonance spectra in p-toluenesulfonamide and 2-nitrobenzoic acid. The 17O nuclear quadrupole resonance frequencies from a sulfonamide group are determined for the first time. The proton-oxygen cross-relaxation rates and the proton local frequency in zero external magnetic field are experimentally determined from the nuclear quadrupole double resonance spectra. PMID:18644741

  11. Spin-pseudospin intertwined excitation at the ? = 1 bilayer quantum Hall state investigated by nuclear-spin relaxation

    SciTech Connect

    Tsuda, S.; Nguyen, M. H. [Graduate School of Science, Kyoto University, Kyoto 606-8502 (Japan); Terasawa, D.; Fukuda, A. [Department of Physics, Hyogo College of Medicine, Nishinomiya 663-8501 (Japan); Zheng, Y. D.; Arai, T.; Sawada, A. [Research Center for Low Temperatures and Materials Sciences, Kyoto University, Kyoto 606-8501 (Japan); Ezawa, Z. F. [Advanced Meson Science Laboratory, Riken, Wako 980-8578 (Japan)

    2013-12-04

    We investigate the electron spin degree of freedom at the imbalanced density bilayer ? = 1 quantum Hall states using the resistively detected nuclear-spin-lattice relaxation rate 1/T{sub 1}. Our measurements reveal a continuous change in 1/T{sub 1} for ? = 1 to 0, suggesting that the balanced density ? = 1 state also exhibits electron-spin fluctuations. Moreover, the value of 1/T{sub 1} in the back layer (the layer from which electrons are transferred to the front layer) increases at intermediate density imbalance states. This indicates that the low-energy electron-spin mode, similar to a mode observed in Skyrmion crystals, might extend across the two layers.

  12. Nuclear-Spin Gyroscope Based on an Atomic Co-Magnetometer

    NASA Technical Reports Server (NTRS)

    Romalis, Michael; Komack, Tom; Ghost, Rajat

    2008-01-01

    An experimental nuclear-spin gyroscope is based on an alkali-metal/noblegas co-magnetometer, which automatically cancels the effects of magnetic fields. Whereas the performances of prior nuclear-spin gyroscopes are limited by sensitivity to magnetic fields, this gyroscope is insensitive to magnetic fields and to other external perturbations. In addition, relative to prior nuclear-spin gyroscopes, this one exhibits greater sensitivity to rotation. There is commercial interest in development of small, highly sensitive gyroscopes. The present experimental device could be a prototype for development of nuclear spin gyroscopes suitable for navigation. In comparison with fiber-optic gyroscopes, these gyroscopes would draw less power and would be smaller, lighter, more sensitive, and less costly.

  13. Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization

    E-print Network

    Barnes, Alexander B.

    We describe a cryogenic sample exchange system that dramatically improves the efficiency of magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments by reducing the time required to change samples and by ...

  14. Atomic-Scale Nuclear Spin Imaging Using Quantum-Assisted Sensors in Diamond

    E-print Network

    Bissbort, U.

    Nuclear spin imaging at the atomic level is essential for the understanding of fundamental biological phenomena and for applications such as drug discovery. The advent of novel nanoscale sensors promises to achieve the ...

  15. Nuclear spin relaxation in a vinylidene fluoride and trifluoroethylene copolymer 70/30

    E-print Network

    Boyer, Edmond

    563 Nuclear spin relaxation in a vinylidene fluoride and trifluoroethylene copolymer 70/30 I phase paraélectrique (au-dessus du point de Curie). Abstract. 2014 The spin dynamics of hydrogen fluoride (PVF2) is known to possess a polar crystalline 3 phase were the chains are in the all

  16. The determination of the in situ structure by nuclear spin contrast variation

    SciTech Connect

    Stuhrmann, H.B. [GKSS Forschungszentrum, Geesthacht (Germany); Nierhaus, K.H. [Max-Planch-Institut fuer Molekulare Genetik, Berlin (Germany)

    1994-12-31

    Polarized neutron scattering from polarized nuclear spins in hydrogenous substances opens a new way of contrast variation. The enhanced contrast due to proton spin polarization was used for the in situ structure determination of tRNA of the functional complex of the E.coli ribosome.

  17. Lattice dynamics in spin-crossover nanoparticles through nuclear inelastic scattering

    NASA Astrophysics Data System (ADS)

    Félix, Gautier; Mikolasek, Mirko; Peng, Haonan; Nicolazzi, William; Molnár, Gábor; Chumakov, Aleksandr I.; Salmon, Lionel; Bousseksou, Azzedine

    2015-01-01

    We used nuclear inelastic scattering (NIS) to investigate the lattice dynamics in [Fe(pyrazine)(Ni(CN)4)] spin crossover nanoparticles. The vibrational density of states of iron was extracted from the NIS data, which allowed to determine characteristic thermodynamical and lattice dynamical parameters as well as their spin-state dependence. The optical part of the NIS spectra compares well with the Raman scattering data reflecting the expansion/contraction of the coordination octahedron during the spin transition. From the acoustic part, we extracted the sound velocity in the low-spin (vLS=2073 ±31 m s-1) and high-spin (vHS=1942 ±23 m s-1) states of the particles. The spin-state dependence of this parameter is of primary interest to rationalize the spin-transition behavior in solids as well as its dynamics and finite size effects.

  18. Multipulse operation and optical detection of nuclear spin coherence in a GaAs/AlGaAs quantum well.

    PubMed

    Kondo, Y; Ono, M; Matsuzaka, S; Morita, K; Sanada, H; Ohno, Y; Ohno, H

    2008-11-14

    We demonstrate manipulation of nuclear spin coherence in a GaAs/AlGaAs quantum well by optically detected nuclear magnetic resonance (NMR). A phase shift of the Larmor precession of photoexcited electron spins is detected to read out the hyperfine-coupled nuclear spin polarization. Multipulse NMR sequences are generated to control the population and examine the phase coherence in quadrupolar-split spin-3/2 75As nuclei. The phase coherence among the multilevel nuclear spin states is addressed by application of pulse sequences that are used in quantum gate operations. PMID:19113379

  19. Nuclear Spin Gyroscope Based on an Atomic Comagnetometer T. W. Kornack, R. K. Ghosh, and M. V. Romalis

    E-print Network

    Romalis, Mike

    Nuclear Spin Gyroscope Based on an Atomic Comagnetometer T. W. Kornack, R. K. Ghosh, and M. V; published 29 November 2005) We describe a nuclear spin gyroscope based on an alkali their gyroscopic precession. Spin precession due to magnetic fields as well as their gradients and transients can

  20. Universal dynamics of quantum spin decoherence in a nuclear spin bath Yi-Ya Tian, Pochung Chen, and Daw-Wei Wang

    E-print Network

    Wang, Daw-Wei

    Universal dynamics of quantum spin decoherence in a nuclear spin bath Yi-Ya Tian, Pochung Chen, and Daw-Wei Wang Physics Department, National Tsing-Hua University, Hsinchu, Taiwan 30013, Republic systematically investigate the universal spin decoherence dynamics of a localized electron in an arbitrary

  1. From special unitary groups SU/(2I+1) to nuclear spin statistical weights

    NASA Astrophysics Data System (ADS)

    Ruoff, A.

    2003-06-01

    Following a suggestion of S.R. Polo, Galbraith [J. Chem. Phys. 68 (1978) 1677] was the first to obtain nuclear spin statistical weights for molecules of the type XY4 (T d) , XY5 (D 3h) , and XY6 (O h) starting from special unitary groups. In the present contribution, an analogous but simpler method is presented allowing the calculation of nuclear spin statistical weights of rigid molecules belonging to all important molecular point groups. The molecules under consideration may contain more than one set of identical nuclei with spins up to 3. The method proposed can easily be extended to nonrigid molecules.

  2. Spin-asymmetry energy of nuclear matter Physik-Department T39, Technische Universitt Mnchen, D-85747 Garching, Germany

    E-print Network

    Weise, Wolfram

    Spin-asymmetry energy of nuclear matter N. Kaiser Physik-Department T39, Technische Universität the density-dependent spin-asymmetry energy S kf of isospin-symmetric nuclear matter in the three of freedom in the description of the nuclear many- body dynamics. The contributions to the energy per

  3. Nuclear Spin Dynamics in Double Quantum Dots: Multi-Stability, Dynamical Polarization, Criticality and Entanglement

    E-print Network

    Martin J. A. Schuetz; Eric M. Kessler; Lieven M. K. Vandersypen; J. Ignacio Cirac; Geza Giedke

    2014-05-30

    We theoretically study the nuclear spin dynamics driven by electron transport and hyperfine interaction in an electrically-defined double quantum dot (DQD) in the Pauli-blockade regime. We derive a master-equation-based framework and show that the coupled electron-nuclear system displays an instability towards the buildup of large nuclear spin polarization gradients in the two quantum dots. In the presence of such inhomogeneous magnetic fields, a quantum interference effect in the collective hyperfine coupling results in sizable nuclear spin entanglement between the two quantum dots in the steady state of the evolution. We investigate this effect using analytical and numerical techniques, and demonstrate its robustness under various types of imperfections.

  4. Fluctuations of the tunneling bias created by nuclear spins in molecular nanomagnet Fe-8.

    NASA Astrophysics Data System (ADS)

    Fine, Boris; Tupitsyn, Igor; Stamp, Philip

    2002-03-01

    By now, it has been shown both theoretically and experimentally, that the fluctuations of the tunneling bias due to nuclear spins play a prominent role in the tunneling of magnetization in molecular nanoclusters Fe-8. In the present work, we develop the theoretical description of these fluctuations. Our result is that the fluctuation spectrum of the ``nuclear'' bias has two components: fast and slow. The fast component is due to the misalignment between the direction of the local magnetic field and the nuclear spin projection that contributes to the bias, while the slow component is due to the diffusion of the Zeeman energy of nuclear spins across the crystal. We have computed the time-dependent correlation functions associated with the both components of the fluctuation spectrum.

  5. hal-00133055,version1-29Mar2007 Nuclear spin interferences in bulk water at room temperature.

    E-print Network

    Boyer, Edmond

    hal-00133055,version1-29Mar2007 Nuclear spin interferences in bulk water at room temperature. J in NMR pacs 03.67.-a: Quantum information pacs 67.57.Lm: Spin dynamics Abstract Nuclear spin interference in a static mag- netic field B0 4.7 T. For a homogeneity of B0 of the order of B0/B0 = 2 · 10-8 , the nuclear

  6. Spin-labeled heparins as polarizing agents for dynamic nuclear polarization.

    PubMed

    Dollmann, Björn C; Kleschyov, Andrei L; Sen, Vasily; Golubev, Valery; Schreiber, Laura M; Spiess, Hans W; Münnemann, Kerstin; Hinderberger, Dariush

    2010-12-01

    A potentially biocompatible class of spin-labeled macromolecules, spin-labeled (SL) heparins, and their use as nuclear magnetic resonance (NMR) signal enhancers are introduced. The signal enhancement is achieved through Overhauser-type dynamic nuclear polarization (DNP). All presented SL-heparins show high (1)H DNP enhancement factors up to E=-110, which validates that effectively more than one hyperfine line can be saturated even for spin-labeled polarizing agents. The parameters for the Overhauser-type DNP are determined and discussed. A striking result is that for spin-labeled heparins, the off-resonant electron paramagnetic resonance (EPR) hyperfine lines contribute a non-negligible part to the total saturation, even in the absence of Heisenberg spin exchange (HSE) and electron spin-nuclear spin relaxation (T(1ne)). As a result, we conclude that one can optimize the use of, for example, biomacromolecules for DNP, for which only small sample amounts are available, by using heterogeneously distributed radicals attached to the molecule. PMID:20960494

  7. Sensing and atomic-scale structure analysis of single nuclear spin clusters in diamond

    E-print Network

    Fazhan Shi; Xi Kong; Pengfei Wang; Fei Kong; Nan Zhao; Ren-Bao Liu; Jiangfeng Du

    2013-09-25

    Single-molecule nuclear magnetic resonance (NMR) is a crown-jewel challenge in the field of magnetic resonance spectroscopy and has important applications in chemical analysis and in quantum computing. Recently, it becomes possible to tackle this grand challenge thanks to experimental advances in preserving quantum coherence of nitrogen-vacancy (NV) center spins in diamond as a sensitive probe and theoretical proposals on atomic-scale magnetometry via dynamical decoupling control. Through decoherence measurement of NV centers under dynamical decoupling control, sensing of single $^{13}\\textbf{C}$ at nanometer distance has been realized. Toward the ultimate goal of structure analysis of single molecules, it is highly desirable to directly measure the interactions within single nuclear spin clusters. Here we sensed a single $^{13}\\textbf{C}$-$^{13}\\textbf{C}$ nuclear spin dimer located about 1 nm from the NV center and characterized the interaction between the two nuclear spins, by measuring NV center spin decoherence under various dynamical decoupling control. From the measured interaction we derived the spatial configuration of the dimer with atomic-scale resolution. These results demonstrate that central spin decoherence under dynamical decoupling control is a feasible probe for NMR structure analysis of single molecules.

  8. Nuclear spin lattice relaxation and electric field gradient in liquid indium†

    Microsoft Academic Search

    F. A. Rossini; E. Geissler; E. M. Dickson; W. D. Knight

    1967-01-01

    We have measured the nuclear spin lattice relaxation time in liquid indium from 130°C to 300°C to be: 1\\/T1=(1.98 × 0.0082T) × 103 sec-1. The relaxation rate consists of two significant parts: (1\\/T1)K from the nuclear magnetic hyperfine interaction, and (1\\/T1)Q from the nuclear quadrupole interaction. We calculate (1\\/T1)K from the the modified Korringa relation using a correction factor of

  9. Nuclear spin lattice relaxation and electric field gradient in liquid indium

    Microsoft Academic Search

    F. A. Rossini; E. Geissler; E. M. Dickson; W. D. Knight

    1967-01-01

    We have measured the nuclear spin lattice relaxation time in liquid indium from 130°C to 300°C to be: 1\\/T1=(1.98 × 0.0082T) × 10 sec. The relaxation rate consists of two significant parts: (1\\/T1)K from the nuclear magnetic hyperfine interaction, and (1\\/T1)Q from the nuclear quadrupole interaction. We calculate (1\\/T1)K from the the modified Korringa relation using a correction factor of

  10. TAUTOMERISM AND SITE OF PROTONATION OF 1-METHYLCYTOSINE: PROOF BY NUCLEAR MAGNETIC RESONANCE SPIN-SPIN COUPLING.

    PubMed

    MILES, H T; BRADLEY, R B; BECKER, E D

    1963-12-20

    New nuclear magnetic resonance data lead to a completely unambiguous proof that the predominant tautomeric form of 1-methylcytosine is the amino form and that in acid solution the molecule protonates at 3-N. The close similarity of the nuclear magnetic resonance spectra of this compound to the spectra of the cytosine nucleosides indicates that these structures also exist in the nucleosides. These conclusions are reached on the basis of the spectra of analogs labeled with N15 and of the proton spin decoupling measurements made at low temperature. PMID:14075685

  11. Universal control and error correction in multi-qubit spin registers in diamond

    E-print Network

    T. H. Taminiau; J. Cramer; T. van der Sar; V. V. Dobrovitski; R. Hanson

    2013-09-26

    Quantum registers of nuclear spins coupled to electron spins of individual solid-state defects are a promising platform for quantum information processing. Pioneering experiments selected defects with favourably located nuclear spins having particularly strong hyperfine couplings. For progress towards large-scale applications, larger and deterministically available nuclear registers are highly desirable. Here we realize universal control over multi-qubit spin registers by harnessing abundant weakly coupled nuclear spins. We use the electron spin of a nitrogen-vacancy centre in diamond to selectively initialize, control and read out carbon-13 spins in the surrounding spin bath and construct high-fidelity single- and two-qubit gates. We exploit these new capabilities to implement a three-qubit quantum-error-correction protocol and demonstrate the robustness of the encoded state against applied errors. These results transform weakly coupled nuclear spins from a source of decoherence into a reliable resource, paving the way towards extended quantum networks and surface-code quantum computing based on multi-qubit nodes.

  12. Separation and conversion dynamics of nuclear-spin isomers of gaseous methanol.

    PubMed

    Sun, Zhen-Dong; Ge, Meihua; Zheng, Yujun

    2015-01-01

    All symmetrical molecules with non-zero nuclear spin exist in nature as nuclear-spin isomers (NSIs). However, owing to the lack of experimental information, knowledge is rare about interconversions of NSIs of gaseous molecules with torsional symmetry. Here we report our separation and conversion observations on NSI-torsion-specific transition systems of gaseous methanol from a light-induced drift experiment involving partially spatial separation of the ortho and para isomers. We find that vibrationally excited molecules of the methanol spin isomer have a smaller collision cross-section than their ground-state counterparts. Interconversion of the enriched ortho isomer with the para isomer, which is generally considered improbable, has been quantitatively studied by sensitive detections of the spectral intensities. Rather counterintuitively, this reveals that the interconversion is inhibited with increasing pressure. Our results suggest that the spin conversion mechanism in methanol is via a quantum relaxation process with the quantum Zeno effect induced by molecular collisions. PMID:25880882

  13. Nuclear states and shapes at high spin. [Good review

    SciTech Connect

    Diamond, R.M.

    1980-08-01

    As angular momentum is added to a nucleus, the balance of forces acting upon it to determine its shape, moment of inertia, mode of rotation, and type of level structure may undergo a series of changes. At relatively low spins a deformed nucleus will rotate collectively, and one may see the effect of Coriolis antipairing in gradually increasing the moment of inertia. Around spin 12 to 16 h-bar there may be an abrupt change (backbending) when a pair of high-j nucleons unpairs and the nucleons align with the axis of rotation; this process allows the nucleus to slow its collective rotation. This process, the start of a sharing of angular momentum between single-particle motion and the collective rotation, gives a lower total energy and corresponds to a change toward triaxiality in the shape of the nucleus. At much higher spins discrete ..gamma..-ray transitions can no longer be observed. This is the regime of continuum spectra; all the information on these high-spin states (to 65 h-bar) is contained in these continuum cascades. Knowledge is accumulating on how to study these spectra, experimentally and theoretically, and new techniques offer promise of revealing a great deal of information about the shapes and properties of very high spin states. 71 references, 34 figures.

  14. Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves

    SciTech Connect

    Thurber, Kent R., E-mail: thurberk@niddk.nih.gov; Tycko, Robert [Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States)] [Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520 (United States)

    2014-05-14

    We report solid state {sup 13}C and {sup 1}H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, {sup 1}H and cross-polarized {sup 13}C NMR signals from {sup 15}N,{sup 13}C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T{sub 1e} is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations.

  15. Perturbation of nuclear spin polarizations in solid state NMR of nitroxide-doped samples by magic-angle spinning without microwaves.

    PubMed

    Thurber, Kent R; Tycko, Robert

    2014-05-14

    We report solid state (13)C and (1)H nuclear magnetic resonance (NMR) experiments with magic-angle spinning (MAS) on frozen solutions containing nitroxide-based paramagnetic dopants that indicate significant perturbations of nuclear spin polarizations without microwave irradiation. At temperatures near 25 K, (1)H and cross-polarized (13)C NMR signals from (15)N,(13)C-labeled L-alanine in trinitroxide-doped glycerol/water are reduced by factors as large as six compared to signals from samples without nitroxide doping. Without MAS or at temperatures near 100 K, differences between signals with and without nitroxide doping are much smaller. We attribute most of the reduction of NMR signals under MAS near 25 K to nuclear spin depolarization through the cross-effect dynamic nuclear polarization mechanism, in which three-spin flips drive nuclear polarizations toward equilibrium with spin polarization differences between electron pairs. When T1e is sufficiently long relative to the MAS rotation period, the distribution of electron spin polarization across the nitroxide electron paramagnetic resonance lineshape can be very different from the corresponding distribution in a static sample at thermal equilibrium, leading to the observed effects. We describe three-spin and 3000-spin calculations that qualitatively reproduce the experimental observations. PMID:24832263

  16. Universal Long-time Behavior of Nuclear Spin Decays in a Solid

    E-print Network

    Steven W. Morgan; Boris V. Fine; Brian Saam

    2008-05-13

    Magnetic resonance studies of nuclear spins in solids are exceptionally well suited to probe the limits of statistical physics. We report experimental results indicating that isolated macroscopic systems of interacting nuclear spins possess the following fundamental property: spin decays that start from different initial configurations quickly evolve towards the same long-time behavior. This long-time behavior is characterized by the shortest ballistic microscopic timescale of the system and therefore falls outside of the validity range for conventional approximations of statistical physics. We find that the nuclear free induction decay and different solid echoes in hyperpolarized solid xenon all exhibit sinusoidally modulated exponential long-time behavior characterized by identical time constants. This universality was previously predicted on the basis of analogy with resonances in classical chaotic systems.

  17. Sideband cooling while preserving coherences in the nuclear spin state in group-II-like atoms.

    PubMed

    Reichenbach, Iris; Deutsch, Ivan H

    2007-09-21

    We propose a method for laser cooling group-II-like atoms without changing the quantum state of their nuclear spins, thus preserving coherences that are usually destroyed by optical pumping in the cooling process. As group-II-like atoms have a (1)S(0) closed-shell ground state, nuclear spin and electronic angular momentum are decoupled, allowing for their independent manipulation. The hyperfine interaction that couples these degrees of freedom in excited states can be suppressed through the application of external magnetic fields. Our protocol employs resolved-sideband cooling on the forbidden clock transition, (1)S(0) --> (3)P(0), with quenching via coupling to the rapidly decaying (1)P(1) state, deep in the Paschen-Back regime. This makes it possible to laser cool neutral atomic qubits without destroying the quantum information stored in their nuclear spins, as shown in two examples, (171)Yb and (87)Sr. PMID:17930500

  18. Nuclear magnetic relaxation in [sup 13]CH[sub 2] and [sup 13]CH[sub 3] coupled spin systems and variable angle spinning lineshape analysis for quadrupolar nuclei with half integer spins

    SciTech Connect

    Zheng, Z.

    1992-01-01

    The carbon-13 multiplet spin-lattice relaxation in [sup 13]CH[sub 2] and [sup 13]CH[sub 3] spin systems is studied in detail by various nonselective and selective pulse techniques. Simultaneous fitting of the resulting relaxation curves with various rates and initial conditions allows for the extraction of both auto- and cross-correlated dipolar spectral densities which can provide detailed information on the molecular anisotropic reorientation. In addition, the [sup 13]CH[sub 3] coupled spin relaxation can characterize the methyl internal rotation dynamics. The cross-correlation between the dipolar and chemical shift anisotropy (CSA) interactions is found to be appreciable. Dipolar-CSA cross-correlated spectral densities introduce relaxation pathways that couple together magnetization modes with different spin inversion symmetries. Consideration of the dipolar-CSA cross-correlated spectral densities not only improves the accuracy of the measurement of dipolar spectral densities but also allows for the determination of the dipolar-CSA cross-correlated spectral densities themselves, providing a new measure of the anisotropy of the shielding tensor. NMR spectroscopy of quadrupolar nuclei in solids generally yields broad lines even when magic angle spinning is applied. Broadening of the central transition of quadrupolar nuclei with half integer spins is caused by the anisotropy of the second order quadrupolar interaction. A straightforward approach is presented that combines average Hamiltonian theory and a numerical solution of a classical banded matrix describing the equation of motion for a quadrupolar nucleus under variable angle sample spinning conditions. At either of two fourth rank magic angles, a simple three parameter lineshape is obtained, and the three breakpoints are related directly to the quadrupolar constant and its asymmetry parameter.

  19. Theory for cross effect dynamic nuclear polarization under magic-angle spinning in solid state nuclear magnetic resonance: The importance of level crossings

    NASA Astrophysics Data System (ADS)

    Thurber, Kent R.; Tycko, Robert

    2012-08-01

    We present theoretical calculations of dynamic nuclear polarization (DNP) due to the cross effect in nuclear magnetic resonance under magic-angle spinning (MAS). Using a three-spin model (two electrons and one nucleus), cross effect DNP with MAS for electron spins with a large g-anisotropy can be seen as a series of spin transitions at avoided crossings of the energy levels, with varying degrees of adiabaticity. If the electron spin-lattice relaxation time T1e is large relative to the MAS rotation period, the cross effect can happen as two separate events: (i) partial saturation of one electron spin by the applied microwaves as one electron spin resonance (ESR) frequency crosses the microwave frequency and (ii) flip of all three spins, when the difference of the two ESR frequencies crosses the nuclear frequency, which transfers polarization to the nuclear spin if the two electron spins have different polarizations. In addition, adiabatic level crossings at which the two ESR frequencies become equal serve to maintain non-uniform saturation across the ESR line. We present analytical results based on the Landau-Zener theory of adiabatic transitions, as well as numerical quantum mechanical calculations for the evolution of the time-dependent three-spin system. These calculations provide insight into the dependence of cross effect DNP on various experimental parameters, including MAS frequency, microwave field strength, spin relaxation rates, hyperfine and electron-electron dipole coupling strengths, and the nature of the biradical dopants.

  20. Interaction induced deformation in momentum distribution of spin polarized nuclear matter

    E-print Network

    T. Frick; H. Müther; A. Sedrakian

    2002-03-19

    Effects of spin polarization on the structure of symmetric nuclear matter and pure neutron matter are investigated. We show that the spin polarization induces a deformation of the Fermi spheres for nucleons with spin parallel and opposite to the polarization axes. This feature can be related to the structure of the one pion exchange contribution to a realistic nucleon-nucleon interaction. While the anisotropies in the momentum distribution lower the energy of the system by small amount, the associated variations of the single particle energies with the angle between the polarization axis and the particle momentum are significant.

  1. Spin and temperature dependence of nuclear deformation using alpha-gamma angular correlations

    Microsoft Academic Search

    N. G. Nicolis; D. G. Sarantites; L. A. Adler; F. A. Dilmanian; K. Honkanen; Z. Majka; L. G. Sobotka; Z. Li; T. M. Semkow; J. R. Beene

    1987-01-01

    Alpha-particle angular distributions with respect to the spin direction of residual nuclei have been measured in heavy-ion fusion reactions. The spin direction was determined by measuring the ..gamma..-ray angular distributions, for each event, using the spin spectrometer. ..cap alpha..-particle anisotropies have been extracted for the compound nuclear systems: ¹¹°Sn*(94 MeV), ¹¹⁴Sn*(80 MeV), ¹³⁸Nd*(82 MeV), ¹⁶⁴Yb*(67 MeV) and ¹⁷°Yb*(135 MeV) as

  2. Effect of electron spin dynamics on solid-state dynamic nuclear polarization performance.

    PubMed

    Siaw, Ting Ann; Fehr, Matthias; Lund, Alicia; Latimer, Allegra; Walker, Shamon A; Edwards, Devin T; Han, Song-I

    2014-09-21

    For the broadest dissemination of solid-state dynamic nuclear polarization (ssDNP) enhanced NMR as a material characterization tool, the ability to employ generic mono-nitroxide radicals as spin probes is critical. A better understanding of the factors contributing to ssDNP efficiency is needed to rationally optimize the experimental condition for the practically accessible spin probes at hand. This study seeks to advance the mechanistic understanding of ssDNP by examining the effect of electron spin dynamics on ssDNP performance at liquid helium temperatures (4-40 K). The key observation is that bi-radicals and mono-radicals can generate comparable nuclear spin polarization at 4 K and 7 T, which is in contrast to the observation for ssDNP at liquid nitrogen temperatures (80-150 K) that finds bi-radicals to clearly outperform mono-radicals. To rationalize this observation, we analyze the change in the DNP-induced nuclear spin polarization (Pn) and the characteristic ssDNP signal buildup time as a function of electron spin relaxation rates that are modulated by the mono- and bi-radical spin concentration. Changes in Pn are consistent with a systematic variation in the product of the electron spin-lattice relaxation time and the electron spin flip-flop rate that constitutes an integral saturation factor of an inhomogeneously broadened EPR spectrum. We show that the comparable Pn achieved with both radical species can be reconciled with a comparable integral EPR saturation factor. Surprisingly, the largest Pn is observed at an intermediate spin concentration for both mono- and bi-radicals. At the highest radical concentration, the stronger inter-electron spin dipolar coupling favors ssDNP, while oversaturation diminishes Pn, as experimentally verified by the observation of a maximum Pn at an intermediate, not the maximum, microwave (?w) power. At the maximum ?w power, oversaturation reduces the electron spin population differential that must be upheld between electron spins that span a frequency difference matching the (1)H NMR frequency-characteristic of the cross effect DNP. This new mechanistic insight allows us to rationalize experimental conditions where generic mono-nitroxide probes can offer competitive ssDNP performance to that of custom designed bi-radicals, and thus helps to vastly expand the application scope of ssDNP for the study of functional materials and solids. PMID:24968276

  3. Collisionally assisted, highly selective laser isotope separation of carbon-13.

    PubMed

    Polianski, M; Boyarkin, O V; Rizzo, T R

    2004-12-15

    We have further developed our recently reported two-laser technique for highly selective molecular isotope separation of carbon-13 [Boyarkin, Kowalczyk, and Rizzo, J. Chem. Phys. 118, 93 (2003)] with the objective of increasing the yield. An essential feature of this approach in its original conception is the significant increase of isotopic selectivity that occurs through collisions during the time between the overtone preexcitation laser pulse and the multiphoton dissociation pulse. We demonstrate here that under certain conditions, this collisional enhancement of the selectivity works equally well when the two pulses are overlapped in time, allowing the overall isotopic selectivity of the process to remain high while achieving a significant increase in the absolute dissociation yield. We also find that proper shaping of the CO2 laser dissociation pulse makes the fluence required for dissociation sufficiently low to allow irradiation of a large reaction volume by unfocused laser beams. Together, these factors may make this laser isotope separation scheme competitive with existing separation methods. PMID:15634141

  4. Studies of nuclear rotational bands with the spin spectrometer

    Microsoft Academic Search

    L. L. Riedinger; M. P. Carpenter; L. H. Courtney; V. P. Janzen

    1987-01-01

    In the last few years increasingly sophisticated gamma-ray spectrometer arrays have been built at a number of laboratories around the world. These instruments, coupled with versatile heavy-ion accelerators, are capable of probing the detailed behaviour of atomic nuclei under extreme conditions of angular momentum and temperature. Characteristics of one such detector array, the Spin Spectrometer at Oak Ridge National Laboratory,

  5. Fast Nuclear Spin Hyperpolarization of Phosphorus in Silicon D. R. McCamey,1,* J. van Tol,2

    E-print Network

    McCamey, Dane

    is important for a number of its applications. Utilizing the nuclear spin of phosphorus donors as quantum bitsFast Nuclear Spin Hyperpolarization of Phosphorus in Silicon D. R. McCamey,1,* J. van Tol,2 G. W of phosphorus donors in silicon. This polarization is reached with a time constant of $150 sec

  6. Coupled nuclear spin relaxation and internal rotations in magnesium fluosilicate hexahydrate.

    NASA Technical Reports Server (NTRS)

    Utton, D. B.; Tsang, T.

    1972-01-01

    Both proton and fluorine nuclear spin-lattice relaxations have been studied by the 180- to 90-deg pulse method in magnesium fluosilicate hexahydrate at 25 and 13 MHz over the temperature range from 170 to 350 K. Observed nonexponential behavior of the nuclear magnetic relaxation is explained by internal rotations of the doubly charged negative fluosilicate ions and doubly charged positive magnesium hexahydrate ions.

  7. Nuclear-Powered Millisecond Pulsars and the Maximum Spin Frequency of Neutron Stars

    E-print Network

    Deepto Chakrabarty; Edward H. Morgan; Michael P. Muno; Duncan K. Galloway; Rudy Wijnands; Michiel van der Klis; Craig B. Markwardt

    2003-07-01

    Millisecond pulsars are neutron stars (NSs) that are thought to have been spun-up by mass accretion from a stellar companion. It is unknown whether there is a natural brake for this process, or if it continues until the centrifugal breakup limit is reached at submillisecond periods. Many NSs that are accreting from a companion exhibit thermonuclear X-ray bursts that last tens of seconds, caused by unstable nuclear burning on their surfaces. Millisecond brightness oscillations during bursts from ten NSs (as distinct from other rapid X-ray variability that is also observed) are thought to measure the stellar spin, but direct proof of a rotational origin has been lacking. Here, we report the detection of burst oscillations at the known spin frequency of an accreting millisecond pulsar, and we show that these oscillations always have the same rotational phase. This firmly establishes burst oscillations as nuclear-powered pulsations tracing the spin of accreting NSs, corroborating earlier evidence. The distribution of spin frequencies of the 11 nuclear-powered pulsars cuts off well below the breakup frequency for most NS models, supporting theoretical predictions that gravitational radiation losses can limit accretion torques in spinning up millisecond pulsars.

  8. Coherent storage of microwave excitations in rare-earth nuclear spins

    E-print Network

    Gary Wolfowicz; Hannes Maier-Flaig; Robert Marino; Alban Ferrier; Hervé Vezin; John J. L. Morton; Philippe Goldner

    2014-12-23

    Interfacing between various elements of a computer - from memory to processors to long range communication - will be as critical for quantum computers as it is for classical computers today. Paramagnetic rare earth doped crystals, such as Nd$^{3+}$:Y$_2$SiO$_5$ (YSO), are excellent candidates for such a quantum interface: they are known to exhibit long optical coherence lifetimes (for communication via optical photons), possess a nuclear spin (memory) and have in addition an electron spin that can offer hybrid coupling with superconducting qubits (processing). Here we study two of these three elements, demonstrating coherent storage and retrieval between electron and $^{145}$Nd nuclear spin states in Nd$^{3+}$:YSO. We find nuclear spin coherence times can reach 9 ms at $\\approx 5$ K, about two orders of magnitude longer than the electron spin coherence, while quantum state and process tomography of the storage/retrieval operation reveal an average state fidelity of 0.86. The times and fidelities are expected to further improve at lower temperatures and with more homogeneous radio-frequency excitation.

  9. Anomalous nuclear spin relaxation of adsorbed helium-3

    Microsoft Academic Search

    Brian P. Cowan

    1983-01-01

    Within the framework of a general theory of two-dimensional NMR we are able to elucidate certain anomalous features of spin relaxation in adsorbed and porous systems. We explain the linear dependence of relaxation time on applied magnetic field, and this is demonstrated to be related to the relative insensitivity ofT1to temperature. We also show thatT1remains field dependent on the “fast”

  10. Two-dimensional NMR studies of staphylococcal nuclease. 2. Sequence-specific assignments of carbon-13 and nitrogen-15 signals from the nuclease H124L-thymidine 3 prime ,5 prime -bisphosphate-Ca sup 2+ ternary complex

    SciTech Connect

    Wang, J.; Hinck, A.P.; Loh, S.N.; Markley, J.L. (Univ. of Wisconsin, Madison (USA))

    1990-01-09

    Samples of staphylococcal nuclease H124L (cloned protein overproduced in Escherichia coli whose sequence is identical with that of the nuclease isolated from the V8 strain of Staphylococcus aureus) were labeled uniformly with carbon-13 (26% ul {sup 13}C), uniformly with nitrogen-15 (95% ul {sup 15}N), and specifically by incorporating nitrogen-15-labeled leucine ((98% {sup 15}N)Leu) or carbon-13-labeled lysine ((26% ul {sup 13}C)Lys), arginine ((26% ul {sup 13}C)Arg), or methionine ((26% ul {sup 13}C)Met). Solutions of the ternary complexes of these analogues (nuclease H124L-pdTp-Ca{sup 2+}) at pH 5.1 (H{sub 2}O) or pH 5.5 ({sup 2}H{sub 2}O) at 45{degree}C were analyzed as appropriate to the labeling pattern by multinuclear two-dimensional (2D) NMR experiments spectrometer fields of 14.09 and 11.74 T. The results have assisted in spin system assignments and in identification of secondary structural elements. Nuclear Overhauser enhancements (NOE's) characteristic of antiparellel {beta}-sheet (d{sub {alpha}{alpha} }NOE's) were observed in the {sup 1}H({sup 13}C)-SBC-NOE spectrum of the nuclease ternary complex labeled uniformly with {sup 13}C. NOE's characteristic of {alpha}-helix were observed in the {sup 1}H({sup 15}N)SBC-NOE spectrum of the complex prepared from protein labeled uniformly with {sup 15}N. The assignments obtained from these multinuclear NMR studies have confirmed and extended assignments based on {sup 1}H({sup 1}H) 2D NMR experiments.

  11. Solid effect in magic angle spinning dynamic nuclear polarization

    E-print Network

    Smith, Albert A.

    For over five decades, the solid effect (SE) has been heavily utilized as a mechanism for performing dynamic nuclear polarization (DNP). Nevertheless, it has not found widespread application in contemporary, high magnetic ...

  12. Nuclear spin dependence of the reaction of H3+ with H2. I. Kinetics and modeling

    NASA Astrophysics Data System (ADS)

    Crabtree, Kyle N.; Tom, Brian A.; McCall, Benjamin J.

    2011-05-01

    The chemical reaction H_3^+ + H2 ? H2 + H_3^+ is the simplest bimolecular reaction involving a polyatomic, yet is complex enough that exact quantum mechanical calculations to adequately model its dynamics are still unfeasible. In particular, the branching fractions for the "identity," "proton hop," and "hydrogen exchange" reaction pathways are unknown, and to date, experimental measurements of this process have been limited. In this work, the nuclear-spin-dependent steady-state kinetics of the H_3^+ + H2 reaction is examined in detail, and employed to generate models of the ortho:para ratio of H_3^+ formed in plasmas of varying ortho:para H2 ratios. One model is based entirely on nuclear spin statistics, and is appropriate for temperatures high enough to populate a large number of H_3^+ rotational states. Efforts are made to include the influence of three-body collisions in this model by deriving nuclear spin product branching fractions for the H_5^+ + H2 reaction. Another model, based on rate coefficients calculated using a microcanonical statistical approach, is appropriate for lower-temperature plasmas in which energetic considerations begin to compete with the nuclear spin branching fractions. These models serve as a theoretical framework for interpreting the results of laboratory studies on the reaction of H_3^+ with H2.

  13. Angular dependence of nuclear spin echo decay in thin-film yttrium iron garnet

    Microsoft Academic Search

    G. N. Abelyashev; S. N. Polulyah; V. N. Berzhanskij; N. A. Sergeev

    1995-01-01

    The angular dependence of the nuclear spin echo decay of 57Fe in monocrystalline thin-film Y3Fe5O12 was measured. The experimental results for the octahedral Fe3+ a-ions were explained by the orientation fluctuations of the electron magnetization about the local symmetry axis.

  14. Nuclear Spin Relaxation and Molecular Interactions of a Novel Triazolium-Based Ionic Liquid

    SciTech Connect

    Allen, Jesse J.; Schneider, Yanika; Kail, Brian W.; Luebke, David R.; Nulwala, Hunaid; Damodaran, Krishnan

    2013-04-11

    Nuclear spin relaxation, small-angle X-ray scattering (SAXS), and electrospray ionization mass spectrometry (ESI-MS) techniques are used to determine supramolecular arrangement of 3-methyl-1-octyl-4-phenyl-1H-triazol-1,2,3-ium bis(trifluoromethanesulfonyl)imide [OMPhTz][Tf{sub 2}N], an example of a triazolium-based ionic liquid. The results obtained showed first-order thermodynamic dependence for nuclear spin relaxation of the anion. First-order relaxation dependence is interpreted as through-bond dipolar relaxation. Greater than first-order dependence was found in the aliphatic protons, aromatic carbons (including nearest neighbors), and carbons at the end of the aliphatic tail. Greater than first order thermodynamic dependence of spin relaxation rates is interpreted as relaxation resulting from at least one mechanism additional to through-bond dipolar relaxation. In rigid portions of the cation, an additional spin relaxation mechanism is attributed to anisotropic effects, while greater than first order thermodynamic dependence of the octyl side chain’s spin relaxation rates is attributed to cation–cation interactions. Little interaction between the anion and the cation was observed by spin relaxation studies or by ESI-MS. No extended supramolecular structure was observed in this study, which was further supported by MS and SAXS. nuclear Overhauser enhancement (NOE) factors are used in conjunction with spin–lattice relaxation time (T{sub 1}) measurements to calculate rotational correlation times for C–H bonds (the time it takes for the vector represented by the bond between the two atoms to rotate by one radian). The rotational correlation times are used to represent segmental reorientation dynamics of the cation. A combination of techniques is used to determine the segmental interactions and dynamics of this example of a triazolium-based ionic liquid.

  15. The role of level anti-crossings in nuclear spin hyperpolarization.

    PubMed

    Ivanov, Konstantin L; Pravdivtsev, Andrey N; Yurkovskaya, Alexandra V; Vieth, Hans-Martin; Kaptein, Robert

    2014-08-01

    Nuclear spin hyperpolarization is an important resource for increasing the sensitivity of NMR spectroscopy and MRI. Signal enhancements can be as large as 3-4 orders of magnitude. In hyperpolarization experiments, it is often desirable to transfer the initial polarization to other nuclei of choice, either protons or insensitive nuclei such as (13)C and (15)N. This situation arises primarily in Chemically Induced Dynamic Nuclear Polarization (CIDNP), Para-Hydrogen Induced Polarization (PHIP), and the related Signal Amplification By Reversible Exchange (SABRE). Here we review the recent literature on polarization transfer mechanisms, in particular focusing on the role of Level Anti-Crossings (LACs) therein. So-called "spontaneous" polarization transfer may occur both at low and high magnetic fields. In addition, transfer of spin polarization can be accomplished by using especially designed pulse sequences. It is now clear that at low field spontaneous polarization transfer is primarily due to coherent spin-state mixing under strong coupling conditions. However, thus far the important role of LACs in this process has not received much attention. At high magnetic field, polarization may be transferred by cross-relaxation effects. Another promising high-field technique is to generate the strong coupling condition by spin locking using strong radio-frequency fields. Here, an analysis of polarization transfer in terms of LACs in the rotating frame is very useful to predict which spin orders are transferred depending on the strength and frequency of the B1 field. Finally, we will examine the role of strong coupling and LACs in magnetic-field dependent nuclear spin relaxation and the related topic of long-lived spin-states. PMID:25142733

  16. Coherent transfer of nuclear spin polarization in field-cycling NMR experiments

    SciTech Connect

    Pravdivtsev, Andrey N.; Yurkovskaya, Alexandra V.; Ivanov, Konstantin L., E-mail: ivanov@tomo.nsc.ru [International Tomography Center, Siberian Branch of the Russian Academy of Science, Institutskaya 3a, Novosibirsk 630090 (Russian Federation); Novosibirsk State University, Pirogova 2, Novosibirsk 630090 (Russian Federation); Vieth, Hans-Martin [Institut für Experimental Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195 (Germany)] [Institut für Experimental Physik, Freie Universität Berlin, Arnimallee 14, Berlin 14195 (Germany)

    2013-12-28

    Coherent polarization transfer effects in a coupled spin network have been studied over a wide field range. The transfer mechanism is based on exciting zero-quantum coherences between the nuclear spin states by means of non-adiabatic field jump from high to low magnetic field. Subsequent evolution of these coherences enables conversion of spin order in the system, which is monitored after field jump back to high field. Such processes are most efficient when the spin system passes through an avoided level crossing during the field variation. The polarization transfer effects have been demonstrated for N-acetyl histidine, which has five scalar coupled protons; the initial spin order has been prepared by applying RF-pulses at high magnetic field. The observed oscillatory transfer kinetics is taken as a clear indication of a coherent mechanism; level crossing effects have also been demonstrated. The experimental data are in very good agreement with the theoretical model of coherent polarization transfer. The method suggested is also valid for other types of initial polarization in the spin system, most notably, for spin hyperpolarization.

  17. Dynamic nuclear polarization and Hanle effect in (In,Ga)As/GaAs quantum dots. Role of nuclear spin fluctuations

    SciTech Connect

    Gerlovin, I. Ya. [Spin Optics Laboratory, Saint Petersburg State University, Petrodvorets, 198504 St. Petersburg (Russian Federation); Cherbunin, R. V.; Ignatiev, I. V.; Kuznetsova, M. S.; Verbin, S. Yu. [Spin Optics Laboratory, Saint Petersburg State University, Petrodvorets, 198504 St. Petersburg, Russia and Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund (Germany); Flisinski, K.; Bayer, M. [Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund (Germany); Reuter, D.; Wieck, A. D. [Angewandte Festkörperphysik, Ruhr-Universität Bochum, D-44780 Bochum (Germany); Yakovlev, D. R. [Experimentelle Physik 2, Technische Universität Dortmund, D-44221 Dortmund, Germany and A. F. Ioffe Physical-Technical Institute, Russian Academy of Sciences, 194021 St. Petersburg (Russian Federation)

    2013-12-04

    The degree of circular polarization of photoluminescence of (In,Ga)As quantum dots as a function of magnetic field applied perpendicular to the optical axis (Hanle effect) is experimentally studied. The measurements have been performed at various regimes of the optical excitation modulation. The analysis of experimental data has been performed in the framework of a vector model of regular nuclear spin polarization and its fluctuations. The analysis allowed us to evaluate the magnitude of nuclear polarization and its dynamics at the experimental conditions used.

  18. Advances and applications of dynamic-angle spinning nuclear magnetic resonance

    SciTech Connect

    Baltisberger, J.H.

    1993-06-01

    This dissertation describes nuclear magnetic resonance experiments and theory which have been developed to study quadrupolar nuclei (those nuclei with spin greater than one-half) in the solid state. Primarily, the technique of dynamic-angle spinning (DAS) is extensively reviewed and expanded upon in this thesis. Specifically, the improvement in both the resolution (two-dimensional pure-absorptive phase methods and DAS angle choice) and sensitivity (pulse-sequence development), along with effective spinning speed enhancement (again through choice of DAS conditions or alternative multiple pulse schemes) of dynamic-angle spinning experiment was realized with both theory and experimental examples. The application of DAS to new types of nuclei (specifically the {sup 87}Rb and {sup 85}Rb nuclear spins) and materials (specifically amorphous solids) has also greatly expanded the possibilities of the use of DAS to study a larger range of materials. This dissertation is meant to demonstrate both recent advances and applications of the DAS technique, and by no means represents a comprehensive study of any particular chemical problem.

  19. All-optical NMR in semiconductors provided by resonant cooling of nuclear spins interacting with electrons in the resonant spin amplification regime

    NASA Astrophysics Data System (ADS)

    Zhukov, E. A.; Greilich, A.; Yakovlev, D. R.; Kavokin, K. V.; Yugova, I. A.; Yugov, O. A.; Suter, D.; Karczewski, G.; Wojtowicz, T.; Kossut, J.; Petrov, V. V.; Dolgikh, Yu. K.; Pawlis, A.; Bayer, M.

    2014-08-01

    Resonant cooling of different nuclear isotopes manifested in optically induced nuclear magnetic resonances (NMR) is observed in n-doped CdTe/(Cd,Mg)Te and ZnSe/(Zn,Mg)Se quantum wells and for donor-bound electrons in ZnSe:F and GaAs epilayers. By time-resolved Kerr rotation used in the regime of resonant spin amplification, we can expand the range of magnetic fields where the effect can be observed up to nuclear Larmor frequencies of 170 kHz. The mechanism of the resonant cooling of the nuclear spin system is analyzed theoretically. The developed approach allows us to model the resonant spin amplification signals with NMR features.

  20. Spin-orbit decomposition of ab initio nuclear wave functions

    NASA Astrophysics Data System (ADS)

    Johnson, Calvin W.

    2015-03-01

    Although the modern shell-model picture of atomic nuclei is built from single-particle orbits with good total angular momentum j , leading to j -j coupling, decades ago phenomenological models suggested that a simpler picture for 0 p -shell nuclides can be realized via coupling of the total spin S and total orbital angular momentum L . I revisit this idea with large-basis, no-core shell-model calculations using modern ab initio two-body interactions and dissect the resulting wave functions into their component L - and S -components. Remarkably, there is broad agreement with calculations using the phenomenological Cohen-Kurath forces, despite a gap of nearly 50 years and six orders of magnitude in basis dimensions. I suggest that L -S decomposition may be a useful tool for analyzing ab initio wave functions of light nuclei, for example, in the case of rotational bands.

  1. The influence of fertilizer nitrogen and season on the carbon-13 abundance of wheat straw

    Microsoft Academic Search

    D. S. Jenkinson; K. Coleman; D. D. Harkness

    1995-01-01

    Carbon-13 abundance, expressed as ?13C in ‰, was measured in wheat straw grown between 1984 and 1989 on the Broadbalk Continuous Wheat Experiment at Rothamsted.\\u000a In all six years, straw grown without fertilizer N contained less carbon-13 (i.e.?13C was more negative) than straw grown with fertilizer, although the magnitude of this difference varied with year. In a dry\\u000a year, when

  2. Shell structure at high spin and the influence on nuclear shapes

    SciTech Connect

    Khoo, T.L.; Chowdhury, P.; Ahmad, I.

    1982-01-01

    Nuclear structure at high spin is influenced by a combination of liquid-drop and shell-structure effects. For N < 86 both contribute towards the occurrence along the yrast line of high-spin oblate aligned-particle configurations. Shell effects are mainly responsible for the prolate deformation of nuclei with N > 90. The competition between oblate and prolate driving effects leads to a prolate-to-oblate shape transition in /sup 154/Dy/sub 88/. The role of rotation-aligned configurations in the shape change is discussed.

  3. Investigation of a new model of dipolar-coupled nuclear spin relaxation and applications of dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Sorte, Eric G.

    This work presents the results of various investigations using various techniques of hyperpolarizing the nuclei of atoms. Hyperpolarization implies magnetic order in excess of the thermal order obtained naturally as described by Curie's law. The main portion of this work presents the results of a detailed experimental exploration of predictions arising from a new model of transverse nuclear spin relaxation in quantum systems, based on possible manifestations of microscopic chaos in quantum systems. Experiments have been carried out on a number of hyperpolarized xenon samples, each differing in its relative percentage of xenon isotopes in order to vary the homonuclear and heteronuclear dipole couplings in the spin system. The experiments were performed under a variety of conditions in an attempt to observe the behaviors predicted by the model. Additionally, much more extensive measurements were made on a number of samples of solid CaF2 in both single crystal and powder forms. These samples, although thermally polarized, were observed with superior signal to noise ratios than even the hyperpolarized xenon solids, allowing for more precise measurements for comparison to the theory. This work thus contains the first experimental evidence for the majority of the model's predictions. Additionally, this work contains the first precise measurements of the frequency-shift enhancement parameters for 129Xe and krypton in the presence of spin-polarized Rb. The determination of these important numbers will be useful to many groups who utilize spin-exchange optical pumping in their labs. This work built on the prior knowledge of a precise number for the frequency-shift enhancement parameter of 3He in Rb vapor. Finally, I detail work using NMR to detect nuclear-spin polarization enhancement in silicon phosphorus by a novel, photo-induced hyperpolarization technique developed by the Boehme research group at the University of Utah. Significant nuclear polarization enhancements were observed by the Boehme group due to electron-photon interactions in semiconductor soilds; these enhancements were observed by their effects on the ambient electrons and measured with electron spin resonance techniques. The work described here details experiments to observe the enhanced nuclear polarization by directly measuring the intensity increase in an NMR measurement. I will conclude this dissertation with a brief appendix giving a summary of one additional project involving the use of high pressure fluorinated gas NMR to measure the internal topology and characteristics of energy-rich oil shales.

  4. Spin

    Microsoft Academic Search

    Klaus Hentschel

    According to quantum mechanics, spin—the intrinsic angular momentum of an electron, nucleus, or elementary particle at rest—is\\u000a a decidedly nonclassical concept. The ? spin statistics theorem of ? quantum statistics distinguishes bosons and fermions\\u000a obeying ? Bose-Einstein statistics or ? Fermi-Dirac statistics, respectively, depending on whether the particle's spin is\\u000a an even or odd multiple of h\\/2, with h =

  5. Preparation of Non-equilibrium Nuclear Spin States in Double Quantum Dots

    E-print Network

    M. Gullans; J. J. Krich; J. M. Taylor; B. I. Halperin; M. D. Lukin

    2014-07-25

    We theoretically study the dynamic polarization of lattice nuclear spins in GaAs double quantum dots containing two electrons. In our prior work [Phys. Rev. Lett. 104, 226807 (2010)] we identified three regimes of long-term dynamics, including the build up of a large difference in the Overhauser fields across the dots, the saturation of the nuclear polarization process associated with formation of so-called "dark states," and the elimination of the difference field. In particular, when the dots are different sizes we found that the Overhauser field becomes larger in the smaller dot. Here we present a detailed theoretical analysis of these problems including a model of the polarization dynamics and the development of a new numerical method to efficiently simulate semiclassical central-spin problems. When nuclear spin noise is included, the results agree with our prior work indicating that large difference fields and dark states are stable configurations, while the elimination of the difference field is unstable; however, in the absence of noise we find all three steady states are achieved depending on parameters. These results are in good agreement with dynamic nuclear polarization experiments in double quantum dots.

  6. High-pressure magic angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Hoyt, David W.; Turcu, Romulus V. F.; Sears, Jesse A.; Rosso, Kevin M.; Burton, Sarah D.; Felmy, Andrew R.; Hu, Jian Zhi

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure rotor loading/reaction chamber for in situ sealing and re-opening of the high-pressure MAS rotor, and a MAS probe with a localized RF coil for background signal suppression, is reported. The unusual technical challenges associated with development of a reusable high-pressure MAS rotor are addressed in part by modifying standard ceramics for the rotor sleeve by abrading the internal surface at both ends of the cylinder. In this way, not only is the advantage of ceramic cylinders for withstanding very high-pressure utilized, but also plastic bushings can be glued tightly in place so that other removable plastic sealing mechanisms/components and O-rings can be mounted to create the desired high-pressure seal. Using this strategy, sealed internal pressures exceeding 150 bars have been achieved and sustained under ambient external pressure with minimal loss of pressure for 72 h. As an application example, in situ13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg 2SiO 4) reacted with supercritical CO 2 and H 2O at 150 bar and 50 °C are reported, with relevance to geological sequestration of carbon dioxide.

  7. Spin-dipole strength functions of 4He with realistic nuclear forces

    NASA Astrophysics Data System (ADS)

    Horiuchi, W.; Suzuki, Y.

    2013-03-01

    Both isoscalar and isovector spin-dipole excitations of 4He are studied using realistic nuclear forces in the complex scaling method. The ground state of 4He and discretized continuum states with J?=0-,1-,2- for A=4 nuclei are described in explicitly correlated Gaussians reinforced with global vectors for angular motion. Two- and three-body decay channels are specifically treated to take into account final state interactions. The observed resonance energies and widths of the negative-parity levels are all in fair agreement with those calculated from both the spin-dipole and electric-dipole strength functions as well as the energy eigenvalues of the complex scaled Hamiltonian. Spin-dipole sum rules, both non-energy-weighted and energy-weighted, are discussed in relation to tensor correlations in the ground state of 4He.

  8. Room-temperature high-speed nuclear-spin quantum memory in diamond

    E-print Network

    J. H. Shim; I. Niemeyer; J. Zhang; D. Suter

    2013-01-03

    Quantum memories provide intermediate storage of quantum information until it is needed for the next step of a quantum algorithm or a quantum communication process. Relevant figures of merit are therefore the fidelity with which the information can be written and retrieved, the storage time, and also the speed of the read-write process. Here, we present experimental data on a quantum memory consisting of a single $^{13}$C nuclear spin that is strongly coupled to the electron spin of a nitrogen-vacancy (NV) center in diamond. The strong hyperfine interaction of the nearest-neighbor carbon results in transfer times of 300 ns between the register qubit and the memory qubit, with an overall fidelity of 88 % for the write - storage - read cycle. The observed storage times of 3.3 ms appear to be limited by the T$_1$ relaxation of the electron spin. We discuss a possible scheme that may extend the storage time beyond this limit.

  9. Optical and Nuclear Spin Spectroscopy in PRASEODYMIUM(3+):LANTHANUM Fluoride by Optical Pumping

    NASA Astrophysics Data System (ADS)

    Wald, Lawrence Leroy

    A Stark Modulated Optical Pumping (SMOP) technique was used as a sensitive probe of optical hole-burning to study the effects of nuclear spin interactions in Pr ^{3+}:LaF_3. The results of two experiments are reported. In the first experiment, the SMOP technique is applied for optical detection of the NQR spectrum of the Pr^{3+} optical ground state. Frequency and linewidth variations of the Pr ^{3+} ground state hyperfine levels for different positions within the main ^3 H_4(Gamma1) -^1D_2(Gamma 1) inhomogeneous optical line and satellite transitions of Pr^{3+}:LaF _3 are observed. A linear increase in the broadening of the Pr^{3+} hyperfine transitions, without a shift of central frequency, is measured as the laser is tuned toward the wings of the inhomogeneous optical transition. The linear variation is attributed to electric quadrupole broadening caused by changes in local density of point defects across the Stark broadened optical transition. The optically detected NQR spectra of the satellite transitions associated with Pr ion pairs are shifted in frequency, and for most satellites are narrower in width than the NQR spectra found in the wings of the main inhomogeneous optical line. In the second experiment, direct evidence for the presence of a spin diffusion barrier or "frozen core" in Pr^{3+}:LaF _3 is observed by examining the cross relaxation between the Pr and F nuclei in a magnetic field chosen so that a pair of the optical ground state Pr^ {3+} hyperfine energy levels matches the F splitting or a multiple of the F splitting. This level crossing condition allows resonant flip-flop interactions with the nearest neighbor frozen core fluorine spins to re-populate Pr^{3+} hyperfine levels emptied by laser hole-burning, and is detected as enhanced absorption of the laser beam. The coupling of core fluorine spins to bulk fluorine spins during Pr-F cross-relaxation is measured by NMR of the bulk fluorine spin magnetization. The rate of cross relaxation between the Pr spins and the bulk F spins measured in this way is at least three to four orders of magnitude slower than that expected in the absence of a spin diffusion barrier. This reduction of coupling indicates nearly complete de-tuning of the frozen core F spins immediately surrounding the Pr^{3+} ion, cutting off resonant coupling with the bulk F spins.

  10. 1H nuclear spin relaxation of liquid water from molecular dynamics simulations.

    PubMed

    Calero, C; Martí, J; Guàrdia, E

    2015-02-01

    We have investigated the nuclear spin relaxation properties of (1)H in liquid water with the help of molecular dynamics simulations. We have computed the (1)H nuclear spin relaxation times T1 and T2 and determined the contribution of the different interactions to the relaxation at different temperatures and for different classical water models (SPC/E, TIP3P, TIP4P, and TIP4P/2005). Among the water models considered, the TIP4P/2005 model exhibits the best agreement with the experiment. The same analysis was performed with Car-Parrinello ab initio molecular dynamics simulations of bulk water at T = 330 K, which provided results close to the experimental values at room temperature. To complete the study, we have successfully accounted for the temperature-dependence of T1 and T2 in terms of a simplified model, which considers the reorientation in finite angle jumps and the diffusive translation of water molecules. PMID:25584483

  11. Nuclear Spins as Quantum Testbeds: Singlet States, Quantum Correlations, and Delayed-choice Experiments

    E-print Network

    Soumya Singha Roy

    2012-10-28

    Nuclear Magnetic Resonance (NMR) forms a natural test-bed to perform quantum information processing (QIP) and has so far proven to be one of the most successful quantum information processors. The nuclear spins in a molecule treated as quantum bits or qubits which are the basic building blocks of a quantum computer. The development of NMR over half a century puts it in a platform where we can utilize its excellent control techniques over an ensemble of spin systems and perform quantum computation in a highly controlled way. Apart from a successful quantum information processor, NMR is also a highly powerful quantum platform where many of the potentially challenging quantum mechanical experiments can be performed.

  12. The Low-Temperature Nuclear Spin Equilibrium of H_3^+ in Collisions with H_2

    NASA Astrophysics Data System (ADS)

    Grussie, Florian; Berg, Max H.; Wolf, Andreas; Kreckel, Holger; Crabtree, Kyle N.; McCall, Benjamin J.; Gartner, Sabrina; Schlemmer, Stephan

    2013-06-01

    Observations of H_3^+ in diffuse molecular clouds have revealed that the ratio of its ortho and para nuclear spin modifications are not in thermodynamic equilibrium with the environment. This discrepancy could be explained if the reaction H_3^+ + H_2 to H_2 + H_3^+, which interconverts the nuclear spin modifications of H_3^+, has a nonthermal outcome at low temperatures, possibly arising from nuclear spin selection rules on systems of identical fermions. While the nuclear spin dependence of this reaction has previously been investigated experimentally, the prior measurements were limited to temperatures above ˜130 K, well above the 50-70 K typical of diffuse molecular clouds. To investigate whether the outcome of the H_3^+ + H_2 reaction is nonthermal, H_3^+ ions were allowed to interact with H_2 in the temperature-controlled environment of a 22-pole radiofrequency ion trap, and the relative abundances of ortho- and para-H_3^+ at steady state were measured using action spectroscopy. By carefully controlling the ortho:para ratio of the H_2 samples in conjunction with the ion trap temperature, the outcome of the reaction was observed to be close to thermodynamic equilibrium over the temperature range of 45-100 K. Thus, the nonequilibrium ortho:para ratio of H_3^+ observed in diffuse molecular clouds does not arise from a nonthermal outcome of the H_3^+ + H_2 reaction at low temperature. This implies that the origin of the discrepancy lies in the respective formation and destruction mechanisms of H_3^+.

  13. Nuclear Ground State Spins of the Francium Isotopes 208-213, 220-222Fr

    Microsoft Academic Search

    C. Ekström; S. Ingelman; G. Wannberg; M. Skarestad

    1978-01-01

    The nuclear ground state spins of some francium isotopes have been measured using on-line atomic-beam magnetic resonance techniques. The following results have been obtained: 208Fr I = 7, 209Fr I = 9\\/2, 210Fr I = 6, 211Fr I = 9\\/2, 212Fr I = 5, 213Fr I = 9\\/2, 220Fr I = 1, 221Fr I = 5\\/2 and 222Fr I =

  14. Discrimination of nuclear spin isomers exploiting the excited state dynamics of a quinodimethane derivative

    SciTech Connect

    Obaid, Rana [Institut für Theoretische Chemie, Universität Wien, Währinger Str. 17, 1090 Wien (Austria); Faculty of Pharmacy, Al-Quds University, Abu Dis, Palestine (Country Unknown); Kinzel, Daniel; Oppel, Markus, E-mail: markus.oppel@univie.ac.at; González, Leticia [Institut für Theoretische Chemie, Universität Wien, Währinger Str. 17, 1090 Wien (Austria)

    2014-10-28

    Despite the concept of nuclear spin isomers (NSIs) exists since the early days of quantum mechanics, only few approaches have been suggested to separate different NSIs. Here, a method is proposed to discriminate different NSIs of a quinodimethane derivative using its electronic excited state dynamics. After electronic excitation by a laser field with femtosecond time duration, a difference in the behavior of several quantum mechanical operators can be observed. A pump-probe experimental approach for separating these different NSIs is then proposed.

  15. Relativistic theory of nuclear spin-rotation tensor with kinetically balanced rotational London orbitals

    SciTech Connect

    Xiao, Yunlong; Zhang, Yong; Liu, Wenjian, E-mail: liuwjbdf@gmail.com [Beijing National Laboratory for Molecular Sciences, Institute of Theoretical and Computational Chemistry, State Key Laboratory of Rare Earth Materials Chemistry and Applications, College of Chemistry and Molecular Engineering, and Center for Computational Science and Engineering, Peking University, Beijing 100871 (China)

    2014-10-28

    Both kinetically balanced (KB) and kinetically unbalanced (KU) rotational London orbitals (RLO) are proposed to resolve the slow basis set convergence in relativistic calculations of nuclear spin-rotation (NSR) coupling tensors of molecules containing heavy elements [Y. Xiao and W. Liu, J. Chem. Phys. 138, 134104 (2013)]. While they perform rather similarly, the KB-RLO Ansatz is clearly preferred as it ensures the correct nonrelativistic limit even with a finite basis. Moreover, it gives rise to the same “direct relativistic mapping” between nuclear magnetic resonance shielding and NSR coupling tensors as that without using the London orbitals [Y. Xiao, Y. Zhang, and W. Liu, J. Chem. Theory Comput. 10, 600 (2014)].

  16. Relativistic theory of nuclear spin-rotation tensor with kinetically balanced rotational London orbitals

    NASA Astrophysics Data System (ADS)

    Xiao, Yunlong; Zhang, Yong; Liu, Wenjian

    2014-10-01

    Both kinetically balanced (KB) and kinetically unbalanced (KU) rotational London orbitals (RLO) are proposed to resolve the slow basis set convergence in relativistic calculations of nuclear spin-rotation (NSR) coupling tensors of molecules containing heavy elements [Y. Xiao and W. Liu, J. Chem. Phys. 138, 134104 (2013)]. While they perform rather similarly, the KB-RLO Ansatz is clearly preferred as it ensures the correct nonrelativistic limit even with a finite basis. Moreover, it gives rise to the same "direct relativistic mapping" between nuclear magnetic resonance shielding and NSR coupling tensors as that without using the London orbitals [Y. Xiao, Y. Zhang, and W. Liu, J. Chem. Theory Comput. 10, 600 (2014)].

  17. Nuclear tetrahedral states and high-spin states studied using quantum number projection method

    E-print Network

    S. Tagami; M. Shimada; Y. Fujioka; Y. R. Shimizu; J. Dudek

    2014-04-21

    We have recently developed an efficient method of performing the full quantum number projection from the most general mean-field (HFB type) wave functions including the angular momentum, parity as well as the proton and neutron particle numbers. With this method, we have been investigating several nuclear structure mechanisms. In this report, we discuss the obtained quantum rotational spectra of the tetrahedral nuclear states formulating certain experimentally verifiable criteria, of the high-spin states, focussing on the wobbling- and chiral-bands, and of the drip-line nuclei as illustrative examples.

  18. Deep Inelastic Scattering of Polarized Electrons off Polarized $^3$HE: Nuclear Effects and the Neutron Spin Structure Function

    E-print Network

    C. Ciofi degli Atti; E. Pace; G. Salme`; S. Scopetta

    1993-10-22

    Nuclear effects in Deep Inelastic Scattering of polarized electrons off polarized $^3$He are analyzed in terms of a spin dependent spectral function taking into account $S'$ and $D$ waves in $^3$He, as well as Fermi motion and binding effects. A simple and reliable equation relating the neutron and $^3$He spin structure functions is proposed.

  19. Nuclear structure aspects of spin-independent WIMP scattering off xenon

    E-print Network

    Vietze, L; Menéndez, J; Haxton, W C; Schwenk, A

    2014-01-01

    We study the structure factors for spin-independent WIMP scattering off xenon based on state-of-the-art large-scale shell-model calculations, which are shown to yield a good spectroscopic description of all experimentally relevant isotopes. Our results are based on the leading scalar one-body currents only. At this level and for the momentum transfers relevant to direct dark matter detection, the structure factors are in very good agreement with the phenomenological Helm form factors used to give experimental limits for WIMP-nucleon cross sections. In contrast to spin-dependent WIMP scattering, the spin-independent channel, at the one-body level, is less sensitive to nuclear structure details. In addition, we explicitly show that the structure factors for inelastic scattering are suppressed by ~ 10^{-4} compared to the coherent elastic scattering response. This implies that the detection of inelastic scattering will be able to discriminate clearly between spin-independent and spin-dependent scattering. Finall...

  20. Nuclear structure aspects of spin-independent WIMP scattering off xenon

    E-print Network

    L. Vietze; P. Klos; J. Menéndez; W. C. Haxton; A. Schwenk

    2015-02-19

    We study the structure factors for spin-independent WIMP scattering off xenon based on state-of-the-art large-scale shell-model calculations, which are shown to yield a good spectroscopic description of all experimentally relevant isotopes. Our results are based on the leading scalar one-body currents only. At this level and for the momentum transfers relevant to direct dark matter detection, the structure factors are in very good agreement with the phenomenological Helm form factors used to give experimental limits for WIMP-nucleon cross sections. In contrast to spin-dependent WIMP scattering, the spin-independent channel, at the one-body level, is less sensitive to nuclear structure details. In addition, we explicitly show that the structure factors for inelastic scattering are suppressed by ~ 10^{-4} compared to the coherent elastic scattering response. This implies that the detection of inelastic scattering will be able to discriminate clearly between spin-independent and spin-dependent scattering. Finally, we provide fits for all calculated structure factors.

  1. Exactly solvable spin dynamics of an electron coupled to a large number of nuclei; the electron-nuclear spin echo in a quantum dot

    SciTech Connect

    Kozlov, G. G. [St. Petersburg State University, Institute of Physics (Russian Federation)], E-mail: gkozlov@photonics.phys.spbu.ru

    2007-10-15

    The model used to describe the spin dynamics in quantum dots after optical excitation is considered. Problems of the electron-spin polarization decay and the dependence of the steady-state polarization on magnetic field are solved on the basis of exact diagonalization of the model Hamiltonian. An important role of the nuclear state is shown and methods of its calculation for different regimes of optical excitation are proposed. The effect of spin echo generation after application of a {pi} pulse of a magnetic field is predicted for the system under consideration.

  2. Nuclear spin dependence of hydrogenic plasmas in the laboratory and the diffuse interstellar medium

    NASA Astrophysics Data System (ADS)

    Crabtree, K. N.; Indriolo, N.; Kreckel, H.; Kauffman, C. A.; Tom, B. A.; Becka, E.; McGuire, B. A.; McCall, B. J.

    2011-05-01

    Observations of diffuse molecular clouds have shown that the excitation temperature T(H_3^+) derived from the (J,K) = (1,0) (ortho) and (1,1) (para) rotational levels of H_3^+ does not necessarily agree with the kinetic temperature (T01) inferred from UV measurements of H_2. In four of the five diffuse molecular cloud sight lines for which both H_3^+ and H_2 observations are available, T(H_3^+) is lower than T01 by 30 K. The reaction H_3^+ + H_2 ? H_2 + H_3^+ is expected to thermalize the H_3^+ nuclear spin distribution, but the interplay of nuclear spin selection rules and energetic restrictions at the low temperatures of the diffuse interstellar medium may prevent full thermalization at steady state. Alternatively, the nonthermal distribution could arise if H_3^+ does not experience a sufficient number of thermalizing collisions with H_2 during its lifetime. We have studied the nuclear spin dependence of the reaction of H_3^+ with H_2 in the laboratory by measuring the ortho:para ratio of H_3^+ formed in plasmas of varying ortho:para H_2 ratios. This study was performed in a hollow cathode cell which enabled the first measurements of this reaction at low temperature (130 K). From these measurements, we derived the ratio of the ``proton hop'' and ``hydrogen exchange'' rate coefficients as a function of temperature. The ratio, ?, was found to decrease with temperature, already reaching the statistical limit of 0.5 at a temperature of 130 K. Knowledge of ? enables modeling of the ortho:para ratio of H_3^+ in diffuse molecular clouds. We have modeled the nuclear spin dependence of the formation, thermalization, and destruction processes of H_3^+, and found that the nonthermal distribution is not caused by nuclear spin selection rules or energetic restrictions in the H_3^+ + H_2 reaction. Rather, it is likely caused by incomplete thermalization prior to H_3^+ destruction via electron dissociative recombination.

  3. Nuclear Spin Dependence of Hydrogenic Plasmas in the Laboratory and the Diffuse Interstellar Medium

    NASA Astrophysics Data System (ADS)

    Crabtree, Kyle N.; Indriolo, Nick; Kreckel, Holger; Kauffman, Carrie A.; Tom, Brian A.; Beçka, Eftalda; McGuire, Brett A.; McCall, Benjamin J.

    2011-10-01

    Observations of diffuse molecular clouds have shown that the excitation temperature T(H3+) derived from the (J,K) = (1,0) (ortho) and (1,1) (para) rotational levels of H3+ does not necessarily agree with the kinetic temperature (T01) inferred from UV measurements of H2. In four of the five diffuse molecular cloud sight lines for which both H3+ and H2 observations are available, T(H3+) is lower than T01 by 30 K. The reaction H3+ + H2 ? H2 + H3+ is expected to thermalize the H3+ nuclear spin distribution, but the interplay of nuclear spin selection rules and energetic restrictions at the low temperatures of the diffuse interstellar medium may prevent full thermalization at steady state. Alternatively, the nonthermal distribution could arise if H3+ does not experience a sufficient number of thermalizing collisions with H2 during its lifetime. We have studied the nuclear spin dependence of the reaction of H3+ with H2 in the laboratory by measuring the ortho:para ratio of H3+ formed in plasmas of varying ortho:para H2 ratios. This study was performed in a hollow cathode cell which enabled the first measurements of this reaction at low temperature (130 K). From these measurements, we derived the ratio of the "proton hop" and "hydrogen exchange" rate coefficients as a function of temperature. The ratio, ?, was found to decrease with temperature, already reaching the statistical limit of 0.5 at a temperature of 130 K. Knowledge of ? enables modeling of the ortho:para ratio of H3+ in diffuse molecular clouds. We have modeled the nuclear spin dependence of the formation, thermalization, and destruction processes of H3+, and found that the nonthermal distribution is not caused by nuclear spin selection rules or energetic restrictions in the H3+ + H2 reaction. Rather, it is likely caused by incomplete thermalization prior to H3+ destruction via electron dissociative recombination.

  4. Nuclear Magnetic Spin-Noise and Unusual Relaxation of Oxygen-17 in Water

    NASA Astrophysics Data System (ADS)

    Bendet-Taicher, Eli

    Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) have evolved into widely used techniques, providing diagnostic power in medicine and material sciences due to their high precision and non-invasive nature. Due to the small population differences between spin energy states, a significant sensitivity problem for NMR arises. The low sensitivity of NMR is probably its greatest limitation for applications to biological systems. An alternative probe tuning strategy based on the spin-noise response for application in standard one-dimensional and common high-resolution multidimensional standard biomolecular NMR experiments has shown an increase of up to 50% signal-to-noise (SNR) in one-dimensional NMR experiments and an increase of up to 22% in multi-dimensional ones. The method requires the adjustment of the optimal tuning condition, which may be offset by several hundreds kHz from the conventional tuning settings using the noise response of the water protons as an indicator. This work is described in the first part of the thesis (chapters 2--3). The second part (Chapter 4) of the thesis deals with anomalous oxygen-17 NMR relaxation behavior in water. Oxygen-17 (17O), which has spin of 5/2 and a natural abundance of 0.0373% possesses an electric quadrupole moment. Spin-lattice and spin-spin relaxation occur by the quadrupole interaction, while the J-coupling to 1H spins and exchange are deciding factors. T1 and T2 of 17O in water have been previously measured over a large range of temperatures. The spin-spin relaxation times of 17O as a function of temperature show an anomalous behaviour, expressed by a local maximum at the temperature of maximum density (TMD) of water. It is shown that the same anomalous behaviour shifts to the respective temperatures of maximum density for H2O/D2O solutions with different compositions and salt concentrations. This phenomenon can be correlated to the pH dependency of T2 of 17O in water, and water proton exchange rates at low temperatures that are close to TMD. The investigation of these effects forms the second topic in my thesis. In Chapter 1, some concepts of NMR are introduced as a background to the research work presented. In addition, quadrupolar dynamics of spin-5/2 nuclei is presented to provide the theoretical basis to understand the underlying concepts in Chapter 4. Chapters 2,3 are dedicated to the spin-noise phenomenon and its applications in enhancing SNR, which are based on recent articles, which I authored and co-authored [1, 2]. Chapter 4 is dedicated to research work that centers on the unusual spin-spin relaxation of 17O in water around the TMD. [1] E. Bendet-Taicher, N. Muller, A. Jerschow, Dependence of NMR noise line shapes on tuning, matching, and transmission line properties, Concepts Magn. Reson., 44 (2014) 1--11. [2] M. Nausner, M. Goger, E. Bendet-Taicher, J. Schlagnitweit, A. Jerschow, N. Muller, Signal enhancement in protein NMR using the spin-noise tuning optimum, J Biomol Nmr, 48 (2010) 157--167.

  5. Rotor design for high pressure magic angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Turcu, Romulus V. F.; Hoyt, David W.; Rosso, Kevin M.; Sears, Jesse A.; Loring, John S.; Felmy, Andrew R.; Hu, Jian Zhi

    2013-01-01

    High pressure magic angle spinning (MAS) nuclear magnetic resonance (NMR) with a sample spinning rate exceeding 2.1 kHz and pressure greater than 165 bar has never been realized. In this work, a new sample cell design is reported, suitable for constructing cells of different sizes. Using a 7.5 mm high pressure MAS rotor as an example, internal pressure as high as 200 bar at a sample spinning rate of 6 kHz is achieved. The new high pressure MAS rotor is re-usable and compatible with most commercial NMR set-ups, exhibiting low 1H and 13C NMR background and offering maximal NMR sensitivity. As an example of its many possible applications, this new capability is applied to determine reaction products associated with the carbonation reaction of a natural mineral, antigorite ((Mg,Fe2+)3Si2O5(OH)4), in contact with liquid water in water-saturated supercritical CO2 (scCO2) at 150 bar and 50 °C. This mineral is relevant to the deep geologic disposal of CO2, but its iron content results in too many sample spinning sidebands at low spinning rate. Hence, this chemical system is a good case study to demonstrate the utility of the higher sample spinning rates that can be achieved by our new rotor design. We expect this new capability will be useful for exploring solid-state, including interfacial, chemistry at new levels of high-pressure in a wide variety of fields.

  6. Quadrupolar spectra of nuclear spins in strained InGaAs quantum dots

    E-print Network

    Ceyhun Bulutay

    2012-05-01

    Self-assembled quantum dots (QDs) are born out of lattice mismatched ingredients where strain plays an indispensable role. Through the electric quadrupolar coupling, strain affects the magnetic environment as seen by the nuclear spins. To guide prospective single-QD nuclear magnetic resonance (NMR) as well as dynamic nuclear spin polarization experiments, an atomistic insight to the strain and quadrupolar field distributions is presented. A number of implications of the structural and compositional profile of the QD have been identified. A high aspect ratio of the QD geometry enhances the quadrupolar interaction. The inclined interfaces introduce biaxiality and the tilting of the major quadrupolar principal axis away from the growth axis; the alloy mixing of gallium into the QD enhances both of these features while reducing the quadrupolar energy. Regarding the NMR spectra, both Faraday and Voigt geometries are investigated, unraveling in the first place the extend of inhomogeneous broadening and the appearance of the normally-forbidden transitions. Moreover, it is shown that from the main extend of the NMR spectra the alloy mole fraction of a single QD can be inferred. By means of the element-resolved NMR intensities it is found that In nuclei has a factor of five dominance over those of As. In the presence of an external magnetic field, the borderlines between the quadrupolar and Zeeman regimes are extracted as 1.5 T for In and 1.1 T for As nuclei. At these values the nuclear spin depolarization rates of the respective nuclei get maximized due to the noncollinear secular hyperfine interaction with a resident electron in the QD.

  7. Free-induction decay and envelope modulations in a narrowed nuclear spin bath

    E-print Network

    W. A. Coish; Jan Fischer; Daniel Loss

    2009-11-21

    We evaluate free-induction decay for the transverse components of a localized electron spin coupled to a bath of nuclear spins via the Fermi contact hyperfine interaction. Our perturbative treatment is valid for special (narrowed) bath initial conditions and when the Zeeman energy of the electron $b$ exceeds the total hyperfine coupling constant $A$: $b>A$. Using one unified and systematic method, we recover previous results reported at short and long times using different techniques. We find a new and unexpected modulation of the free-induction-decay envelope, which is present even for a purely isotropic hyperfine interaction without spin echoes and for a single nuclear species. We give sub-leading corrections to the decoherence rate, and show that, in general, the decoherence rate has a non-monotonic dependence on electron Zeeman splitting, leading to a pronounced maximum. These results illustrate the limitations of methods that make use of leading-order effective Hamiltonians and re-exponentiation of short-time expansions for a strongly-interacting system with non-Markovian (history-dependent) dynamics.

  8. Symmetry rearrangement of spin and isospin symmetries and the collective modes in nuclear matter

    SciTech Connect

    He, H. [Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, (Canada) T6G 2Jl] [Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, (Canada) T6G 2Jl; [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (CANADA); [China Institute of Atomic Energy, P.O. Box 275, Beijing, (China); Khanna, F.C. [Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, (Canada) T6G 2Jl] [Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, (Canada) T6G 2Jl; [TRIUMF, 4004 Wesbrook Mall, Vancouver, British Columbia, V6T 2A3 (CANADA); Umezawa, H. [Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, (Canada) T6G 2Jl] [Department of Physics, Theoretical Physics Institute, University of Alberta, Edmonton, Alberta, (Canada) T6G 2Jl

    1997-05-01

    A consistent theory of the spin and isospin excitations in an infinite nuclear system is formulated based on the Ward Takahashi (W{endash}T) relations among various many point Green{close_quote}s functions, which are derived from the requirement of the rotational invariance in spin and isospin space, SU(4). Collective modes are found to be six Nambu{endash}Goldstone bosons, called spin, isospin, and spin-isospin waves, which appear as a result of the symmetry rearrangement of the SU(4) symmetry. The W{endash}T relations are used to determine correlations among collective modes and to obtain a consistent expression for the static susceptibility beyond the random phase approximation. A consistent picture of the isovector collective excitations and their relationship to numerous experimental results is established. A partially conserved isovector current, analogous to a partially conserved axial current, in the symmetry rearrangement of isospin symmetry is established. This helps to define non-pertubatively the finite energy shift due to the explicit symmetry breaking terms. {copyright} 1997 Academic Press, Inc.

  9. Parity mixing of pair at nuclear surface due to spin-orbit potential in $^{18}$F

    E-print Network

    Kanada-En'yo, Yoshiko

    2014-01-01

    We investigate the structure of $^{18}$F with the microscopic wave function based on the three-body $^{16}$O+$p$+$n$ model. In the calculation of the generator coordinate method (GCM) of the three-body model, $T=0$ energy spectra of $J^\\pi=1^+$, $3^+$, and $5^+$ states and $T=1$ spectra of $J^\\pi=0^+$, $2^+$ states in $^{18}$F are described reasonably. Based on the dinucleon picture, the effect of the spin-orbit force on the $T=0$ and $T=1$ $pn$ pairs around the $^{16}$O core is discussed. The $T=1$ pair in the $J^\\pi=0^+$ state gains the spin-orbit potential energy involving the odd-parity mixing in the pair. The spin-orbit potential energy gain with the parity mixing is not so efficient for the $T=0$ pair in the $J^\\pi=1^+$ state. The parity mixing in the pair is regarded as the internal symmetry breaking of the pair in the spin-orbit potential at the nuclear surface.

  10. Ab initio nuclear shielding parameters and spin-rotation coupling constants of FBO, ClBO and FBS

    NASA Astrophysics Data System (ADS)

    Gatehouse, Bethany

    1998-05-01

    Ab initio nuclear shielding parameters and nuclear spin-rotation coupling constants of FBO, ClBO and FBS have been calculated using the multi-configuration self consistent field (MCSCF) method. The dependence of these parameters upon the basis set and active space employed in the calculation was investigated. The results are compared with the experimental values obtained from microwave spectra.

  11. Nuclear magnetic resonance study of spin relaxation and magnetic field gradients in maple leaves.

    PubMed

    McCain, D C

    1995-09-01

    1H Nuclear magnetic resonance techniques were used to measure the distributions of spin-spin relaxation times, T2, and of magnetic field gradients in both the chloroplast and nonchloroplast water compartments of maple leaves (Acer platanoides). Results showed that encounters between water molecules and membranes inside chloroplasts provide an inefficient relaxation mechanism; i.e., chloroplast membranes interact weakly with water molecules. Gradient measurements indirectly measured the sizes of chloroplasts by showing that water in the chloroplasts is confined to small compartments a few microns in diameter. A comparison between measured gradients and gradients calculated for a model leaf indicated that chloroplasts are somewhat more likely to occupy positions along cell walls adjacent to air spaces, but also they may be found in the interiors of cells. PMID:8519965

  12. Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds.

    PubMed

    Panich, A M; Sergeev, N A; Shames, A I; Osipov, V Yu; Boudou, J-P; Goren, S D

    2015-02-25

    Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and (13)C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of (13)C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment. PMID:25646270

  13. Magic radio-frequency dressing of nuclear spins in high-accuracy optical clocks.

    PubMed

    Zanon-Willette, Thomas; de Clercq, Emeric; Arimondo, Ennio

    2012-11-30

    A Zeeman-insensitive optical clock atomic transition is engineered when nuclear spins are dressed by a nonresonant radio-frequency field. For fermionic species as (87)Sr, (171)Yb, and (199)Hg, particular ratios between the radio-frequency driving amplitude and frequency lead to "magic" magnetic values where a net cancelation of the Zeeman clock shift and a complete reduction of first-order magnetic variations are produced within a relative uncertainty below the 10(-18) level. An Autler-Townes continued fraction describing a semiclassical radio-frequency dressed spin is numerically computed and compared to an analytical quantum description including higher-order magnetic field corrections to the dressed energies. PMID:23368116

  14. Impact of hadronic and nuclear corrections on global analysis of spin-dependent parton distributions

    SciTech Connect

    Jimenez-Delgado, Pedro [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Accardi, Alberto [Hampton University, Hampton, VA (United States); Thomas Jefferson National Accelerator Facility, Newport News, VA (United States); Melnitchouk, Wally [Thomas Jefferson National Accelerator Facility, Newport News, VA (United States)

    2014-02-01

    We present the first results of a new global next-to-leading order analysis of spin-dependent parton distribution functions from the most recent world data on inclusive polarized deep-inelastic scattering, focusing in particular on the large-x and low-Q^2 regions. By directly fitting polarization asymmetries we eliminate biases introduced by using polarized structure function data extracted under nonuniform assumptions for the unpolarized structure functions. For analysis of the large-x data we implement nuclear smearing corrections for deuterium and 3He nuclei, and systematically include target mass and higher twist corrections to the g_1 and g_2 structure functions at low Q^2. We also explore the effects of Q^2 and W^2 cuts in the data sets, and the potential impact of future data on the behavior of the spin-dependent parton distributions at large x.

  15. Size dependence of 13C nuclear spin-lattice relaxation in micro- and nanodiamonds

    NASA Astrophysics Data System (ADS)

    Panich, A. M.; Sergeev, N. A.; Shames, A. I.; Osipov, V. Yu; Boudou, J.-P.; Goren, S. D.

    2015-02-01

    Size dependence of physical properties of nanodiamond particles is of crucial importance for various applications in which defect density and location as well as relaxation processes play a significant role. In this work, the impact of defects induced by milling of micron-sized synthetic diamonds was studied by magnetic resonance techniques as a function of the particle size. EPR and 13C NMR studies of highly purified commercial synthetic micro- and nanodiamonds were done for various fractions separated by sizes. Noticeable acceleration of 13C nuclear spin-lattice relaxation with decreasing particle size was found. We showed that this effect is caused by the contribution to relaxation coming from the surface paramagnetic centers induced by sample milling. The developed theory of the spin-lattice relaxation for such a case shows good compliance with the experiment.

  16. EDM measurement in 129Xe atom using dual active feedback nuclear spin maser

    NASA Astrophysics Data System (ADS)

    Sato, T.; Ichikawa, Y.; Ohtomo, Y.; Sakamoto, Y.; Kojima, S.; Funayama, C.; Suzuki, T.; Chikamori, M.; Hikota, E.; Tsuchiya, M.; Furukawa, T.; Yoshimi, A.; Bidinosti, C. P.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.; Asahi, K.

    2014-12-01

    The technique of an active nuclear spin maser is adopted in the search for electric dipole moment in a diamagnetic atom 129Xe. In order to reduce systematic uncertainties arising from long-term drifts of the external magnetic field and from the contact interaction between longitudinal polarized Rb atoms and 129Xe spin, a 3He comagnetometer with a double-cell geometry was employed. The remaining shift, which turned out to show some correlation with the cell temperature, was mitigated by stabilizing the cell temperature. As a result, the frequency drift of the 129Xe maser was reduced from 12 mHz to 700 ?Hz, and the determination precision of frequency of 8.7 nHz was obtained for a 2×104 s measurement time using the double-cell geometry cell.

  17. Optical measurement of the effect of electric fields on the nuclear spin coherence of rare-earth ions in solids.

    PubMed

    Macfarlane, R M; Arcangeli, A; Ferrier, A; Goldner, Ph

    2014-10-10

    We show that the coherence properties of the nuclear spin states of rare-earth ions in solids can be manipulated by small applied electric fields. This was done by measuring the Stark effect on the nuclear quadrupole transitions of (151)Eu in Y(2)SiO(5) (YSO) using a combination of Raman heterodyne optical detection and Stark modulated quadrupole echoes to achieve high sensitivity. The measured Stark coefficients were 0.42 and 1.0 Hz cm/V for the two quadrupole transitions at 34.54 and 46.20 MHz, respectively. The long decoherence time of the nuclear spin states (25 ms) allowed us to make the measurements in very low electric fields of ? 10 V/cm, which produced 100% modulation of the nuclear spin echo, and to measure Stark shifts of ? 1 Hz or 20 ppm of the inhomogeneous linewidth. PMID:25375743

  18. Nuclear spin-lattice relaxation from fractional wobbling in a cone

    E-print Network

    A. E. Sitnitsky

    2011-06-29

    We consider nuclear spin-lattice relaxation rate resulted from a fractional diffusion equation for anomalous rotational wobbling in a cone. The mechanism of relaxation is assumed to be due to dipole-dipole interaction of nuclear spins and is treated within the framework of the standard Bloemberger, Purcell, Pound - Solomon scheme. We consider the general case of arbitrary orientation of the cone axis relative the magnetic field. The BPP-Solomon scheme is shown to remain valid for systems with the distribution of the cone axes depending only on the tilt relative the magnetic field but otherwise being isotropic. We consider the case of random isotropic orientation of cone axes relative the magnetic field taking place in powders. Also we consider the case of their predominant orientation along or opposite the magnetic field and that of their predominant orientation transverse to the magnetic field which may be relevant for, e.g., liquid crystals. Besides we treat in details the model case of the cone axis directed along the magnetic field. The latter provides direct comparison of the limiting case of our formulas with the textbook formulas for ordinary isotropic rotational diffusion. We show that the present model enables one to obtain naturally the well known power law for Larmor frequency dependence of the spin-lattice relaxation rate. The latter is observed in some complex systems. From this law the dependence of the fractional diffusion coefficient on the fractional index is obtained to have a rather simple functional form. The dependence of the spin-lattice relaxation rate on the cone half-width for the case of ordinary rotational diffusion yields results similar to those predicted by the model-free approach.

  19. Nuclear spin optical rotation and Faraday effect in gaseous and liquid water.

    PubMed

    Pennanen, Teemu S; Ikäläinen, Suvi; Lantto, Perttu; Vaara, Juha

    2012-05-14

    Nuclear spin optical rotation (NSOR) of linearly polarized light, due to the nuclear spins through the Faraday effect, provides a novel probe of molecular structure and could pave the way to optical detection of nuclear magnetization. We determine computationally the effects of the liquid medium on NSOR and the Verdet constant of Faraday rotation (arising from an external magnetic field) in water, using the recently developed theory applied on a first-principles molecular dynamics trajectory. The gas-to-liquid shifts of the relevant antisymmetric polarizability and, hence, NSOR magnitude are found to be -14% and -29% for (1)H and (17)O nuclei, respectively. On the other hand, medium effects both enhance the local electric field in water and, via bulk magnetization, the local magnetic field. Together these two effects partially cancel the solvation influence on the single-molecular property. We find a good agreement for the hydrogen NSOR with a recent pioneering experiment on H(2)O(l). PMID:22583295

  20. Achievement of high nuclear spin polarization using lanthanides as low-temperature NMR relaxation agents.

    PubMed

    Peat, David T; Horsewill, Anthony J; Köckenberger, Walter; Perez Linde, Angel J; Gadian, David G; Owers-Bradley, John R

    2013-05-28

    Many approaches are now available for achieving high levels of nuclear spin polarization. One of these methods is based on the notion that as the temperature is reduced, the equilibrium nuclear polarization will increase, according to the Boltzmann distribution. The main problem with this approach is the length of time it may take to approach thermal equilibrium at low temperatures, since nuclear relaxation times (characterized by the spin-lattice relaxation time T1) can become very long. Here, we show, by means of relaxation time measurements of frozen solutions, that selected lanthanide ions, in the form of their chelates with DTPA, can act as effective relaxation agents at low temperatures. Differential effects are seen with the different lanthanides that were tested, holmium and dysprosium showing highest relaxivity, while gadolinium is ineffective at temperatures of 20 K and below. These observations are consistent with the known electron-spin relaxation time characteristics of these lanthanides. The maximum relaxivity occurs at around 10 K for Ho-DTPA and 20 K for Dy-DTPA. Moreover, these two agents show only modest relaxivity at room temperature, and can thus be regarded as relaxation switches. We conclude that these agents can speed up solid state NMR experiments by reducing the T1 values of the relevant nuclei, and hence increasing the rate at which data can be acquired. They could also be of value in the context of a simple low-cost method of achieving several-hundred-fold improvements in polarization for experiments in which samples are pre-polarized at low temperatures, then rewarmed and dissolved immediately prior to analysis. PMID:23588269

  1. Comparison of different methods for calculating the paramagnetic relaxation enhancement of nuclear spins as a function of the magnetic field

    NASA Astrophysics Data System (ADS)

    Belorizky, Elie; Fries, Pascal H.; Helm, Lothar; Kowalewski, Jozef; Kruk, Danuta; Sharp, Robert R.; Westlund, Per-Olof

    2008-02-01

    The enhancement of the spin-lattice relaxation rate for nuclear spins in a ligand bound to a paramagnetic metal ion [known as the paramagnetic relaxation enhancement (PRE)] arises primarily through the dipole-dipole (DD) interaction between the nuclear spins and the electron spins. In solution, the DD interaction is modulated mostly by reorientation of the nuclear spin-electron spin axis and by electron spin relaxation. Calculations of the PRE are in general complicated, mainly because the electron spin interacts so strongly with the other degrees of freedom that its relaxation cannot be described by second-order perturbation theory or the Redfield theory. Three approaches to resolve this problem exist in the literature: The so-called slow-motion theory, originating from Swedish groups [Benetis et al., Mol. Phys. 48, 329 (1983); Kowalewski et al., Adv. Inorg. Chem. 57, (2005); Larsson et al., J. Chem. Phys. 101, 1116 (1994); T. Nilsson et al., J. Magn. Reson. 154, 269 (2002)] and two different methods based on simulations of the dynamics of electron spin in time domain, developed in Grenoble [Fries and Belorizky, J. Chem. Phys. 126, 204503 (2007); Rast et al., ibid. 115, 7554 (2001)] and Ann Arbor [Abernathy and Sharp, J. Chem. Phys. 106, 9032 (1997); Schaefle and Sharp, ibid. 121, 5387 (2004); Schaefle and Sharp, J. Magn. Reson. 176, 160 (2005)], respectively. In this paper, we report a numerical comparison of the three methods for a large variety of parameter sets, meant to correspond to large and small complexes of gadolinium(III) and of nickel(II). It is found that the agreement between the Swedish and the Grenoble approaches is very good for practically all parameter sets, while the predictions of the Ann Arbor model are similar in a number of the calculations but deviate significantly in others, reflecting in part differences in the treatment of electron spin relaxation. The origins of the discrepancies are discussed briefly.

  2. Motional narrowing of 13C dipolar magic-angle-spinning nuclear magnetic resonance spectra

    NASA Astrophysics Data System (ADS)

    Ohe, Hiroshi; Kubo, Atsushi; Katada, Motomi; Sano, Hirotoshi

    1990-09-01

    The effects of molecular motions on the dipolar coupled 13C magic-angle-spinning (MAS) nuclear magnetic resonance (NMR) spectra of alkane—urea inclusion compounds and bis(ethylammonium) hexachlorostannate were investigated. The contact time dependences of 13C cross-polarization (CP) MAS NMR spectra were measured for the tridecane—urea inclusion compounds at the Hartman—Hahn condition and at the off-Hartman—Hahn condition. Rotational echoes were observed at a multiple of the rotational periods both in the dipolar dephasing experiments and the CP experiments. These rotational echo shapes were analyzed by the presently proposed theory.

  3. The Carbon-13 Pockets in AGB Stars and Their Fingerprints in Mainstream SiC Grains

    NASA Astrophysics Data System (ADS)

    Liu, N.; Davis, A. M.; Gallino, R.; Savina, M. R.; Bisterzo, S.; Gyngard, F.; Dauphas, N.; Pellin, M. J.

    2014-09-01

    Strontium, Zr, and Ba isotopic compositions of mainstream presolar SiC grains are used to constrain the concentration and distribution of carbon-13, the main neutron source for the s-process, in the intershell region of asymptotic giant branch stars.

  4. Carbon13 Depletion in a Hydrothermal Vent Mussel: Suggestion of a Chemosynthetic Food Source

    Microsoft Academic Search

    Greg H. Rau; John I. Hedges

    1979-01-01

    Tissues of a mytilid mussel from the Clambake I hydrothermal vent in the Galapagos Rift zone are strikingly depleted in carbon-13 relative to the tissues of other marine organisms. The stable carbon isotope composition of this mussel suggests that chemoautotrophic bacteria present in the hydrothermal waters are a major food source for filter-feeding organisms in this abyssal environment.

  5. Effect of spin-orbit nuclear charge density corrections due to the anomalous magnetic moment on halonuclei

    SciTech Connect

    Ong, A.; Berengut, J. C.; Flambaum, V. V. [School of Physics, University of New South Wales, Sydney 2052 (Australia)

    2010-07-15

    In this paper we consider the contribution of the anomalous magnetic moments of protons and neutrons to the nuclear charge density. We show that the spin-orbit contribution to the mean-square charge radius, which has been neglected in recent nuclear calculations, can be important in light halonuclei. We estimate the size of the effect in helium, lithium, and beryllium nuclei. It is found that the spin-orbit contribution represents a approx2% correction to the charge density at the center of the {sup 7}Be nucleus. We derive a simple expression for the correction to the mean-square charge radius due to the spin-orbit term and find that in light halonuclei it may be larger than the Darwin-Foldy term and comparable to finite size corrections. A comparison of experimental and theoretical mean-square radii including the spin-orbit contribution is presented.

  6. The effect of spin-orbit nuclear charge density corrections due to the anomalous magnetic moment on halonuclei

    E-print Network

    A. Ong; J. C. Berengut; V. V. Flambaum

    2010-06-29

    In this paper we consider the contribution of the anomalous magnetic moments of protons and neutrons to the nuclear charge density. We show that the spin-orbit contribution to the mean-square charge radius, which has been neglected in recent nuclear calculations, can be important in light halonuclei. We estimate the size of the effect in helium, lithium, and beryllium nuclei. It is found that the spin-orbit contribution represents a ~2% correction to the charge density at the center of the Be-7 nucleus. We derive a simple expression for the correction to the mean-square charge radius due to the spin-orbit term and find that in light halonuclei it may be larger than the Darwin-Foldy term and comparable to finite size corrections. A comparison of experimental and theoretical mean-square radii including the spin-orbit contribution is presented.

  7. (2)H-decoupling-accelerated (1)H spin diffusion in dynamic nuclear polarization with photoexcited triplet electrons.

    PubMed

    Negoro, M; Nakayama, K; Tateishi, K; Kagawa, A; Takeda, K; Kitagawa, M

    2010-10-21

    In dynamic nuclear polarization (DNP) experiments applied to organic solids for creating nonequilibrium, high (1)H spin polarization, an efficient buildup of (1)H polarization is attained by partially deuterating the material of interest with an appropriate (1)H concentration. In such a dilute (1)H spin system, it is shown that the (1)H spin diffusion rate and thereby the buildup efficiency of (1)H polarization can further be enhanced by continually applying radiofrequency irradiation for deuterium decoupling during the DNP process. As experimentally confirmed in this work, the electron spin polarization of the photoexcited triplet state is mainly transferred only to those (1)H spins, which are in the vicinity of the electron spins, and (1)H spin diffusion transports the localized (1)H polarization over the whole sample volume. The (1)H spin diffusion coefficients are estimated from DNP repetition interval dependence of the initial buildup rate of (1)H polarization, and the result indicates that the spin diffusion coefficient is enhanced by a factor of 2 compared to that without (2)H decoupling. PMID:20969400

  8. A high-performance Fortran code to calculate spin- and parity-dependent nuclear level densities

    NASA Astrophysics Data System (ADS)

    Sen'kov, R. A.; Horoi, M.; Zelevinsky, V. G.

    2013-01-01

    A high-performance Fortran code is developed to calculate the spin- and parity-dependent shell model nuclear level densities. The algorithm is based on the extension of methods of statistical spectroscopy and implies exact calculation of the first and second Hamiltonian moments for different configurations at fixed spin and parity. The proton-neutron formalism is used. We have applied the method for calculating the level densities for a set of nuclei in the sd-, pf-, and pf+g- model spaces. Examples of the calculations for 28Si (in the sd-model space) and 64Ge (in the pf+g-model space) are presented. To illustrate the power of the method we estimate the ground state energy of 64Ge in the larger model space pf+g, which is not accessible to direct shell model diagonalization due to the prohibitively large dimension, by comparing with the nuclear level densities at low excitation energy calculated in the smaller model space pf. Program summaryProgram title: MM Catalogue identifier: AENM_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/AENM_v1_0.html Program obtainable from: CPC Program Library, Queen's University, Belfast, N. Ireland Licensing provisions: Standard CPC licence, http://cpc.cs.qub.ac.uk/licence/licence.html No. of lines in distributed program, including test data, etc.: 193181 No. of bytes in distributed program, including test data, etc.: 1298585 Distribution format: tar.gz Programming language: Fortran 90, MPI. Computer: Any architecture with a Fortran 90 compiler and MPI. Operating system: Linux. RAM: Proportional to the system size, in our examples, up to 75Mb Classification: 17.15. External routines: MPICH2 (http://www.mcs.anl.gov/research/projects/mpich2/) Nature of problem: Calculating of the spin- and parity-dependent nuclear level density. Solution method: The algorithm implies exact calculation of the first and second Hamiltonian moments for different configurations at fixed spin and parity. The code is parallelized using the Message Passing Interface and a master-slaves dynamical load-balancing approach. Restrictions: The program uses two-body interaction in a restricted single-level basis. For example, GXPF1A in the pf-valence space. Running time: Depends on the system size and the number of processors used (from 1 min to several hours).

  9. Radiative Lifetime for Nuclear Spin Conversion of Water-Ion H_2O^+

    NASA Astrophysics Data System (ADS)

    Tanaka, Keiichi; Harada, Kensuke; Oka, Takeshi

    2013-06-01

    Nuclear spin conversion interaction of the water ion, H_2O^+, has been studied to derive the spontaneous emission lifetime between the ortho- and para-levels. The H_2O^+ ion is a radical with ^2 B _1 electronic ground state and the off-diagonal electron spin-nuclear spin interaction term, T_{ab} (S_a? I_b + S_b? I_a), connects para and ortho levels, because ? {I} = {I}_1 - {I}_2 has nonvanishing matrix elements between I = 0 and 1. The T_{ab} coupling constant, derived by an ab initio calculation in MRD-CI/Bk level to be 72 MHz, is larger than that of H_2O by 4 orders of magnitude, makes the ortho to para conversion of H_2O^+ faster than that of H_2O by 8 orders of magnitude and possibly competitive with other astrophysical processes. Last year we reported ortho and para coupling channels below 900 cm^{-1} caused by accidental near degeneracy of rotational levels. For example, hyperfine components of the 4_{2,2}(o) and 3_{3,0}(p) levels mix each other by 1.2 x 10^{-3} due to the near degeneracy (? E = 0.417 cm^{-1}), but the lower lying 1_{0,1}(p) and 1_{1,1}(o) levels mix only by 8.9 x 10^{-5} because of their large separation (? E = 16.27 cm^{-1}). In the present study, we solved the radiative rate equations including all the rotational levels below 900 cm^{-1} to give the o-p conversion lifetime to be 0.451, 3.27, 398 and 910 years for the equilibrium o/p ratio of 3.00, 3.00, 4.52, and 406 when the radiation temperature T_r is 100, 60, 20 and 5 K. These results qualitatively help to understand the observed high o/p ratio of 4.8 ± 0.5 (corresponding to the nuclear spin temperature of 21 K) toward Sgr B2, but they are too slow to compete with the reaction by collision unless the number of density of H_2 in the region is very low (n˜1 cm^{-3}) or the radiative temperature is very high (T_r > 50K). K. Tanaka, K. Harada, and T. Oka, the 67th OSU Symposium MG06, 2012. P. Schilke, et al., A&A 521, L11 (2010). K. Tanaka, K. Harada, and T. Oka, J. Phys. Chem. A, in press.

  10. Study of spin polarized nuclear matter and finite nuclei with finite range simple effective interaction

    NASA Astrophysics Data System (ADS)

    Behera, B.; Viñas, X.; Routray, T. R.; Centelles, M.

    2015-04-01

    The properties of spin polarized pure neutron matter and symmetric nuclear matter (SNM) are studied using the finite range simple effective interaction, upon its parametrization revisited. Out of the total twelve parameters involved, we now determine ten of them from nuclear matter (NM), against the nine parameters in our earlier calculation, as required in order to have predictions in both spin polarized NM and finite nuclei in unique manner being free from uncertainty found using the earlier parametrization. The information on the effective mass splitting in polarized neutron matter of the microscopic calculations is used to constrain the one more parameter, that was earlier determined from finite nucleus, and in doing so the quality of the description of finite nuclei is not compromised. The interaction with the new set of parameters is used to study the possibilities of ferromagnetic and antiferromagnetic transitions in completely polarized SNM. Emphasis is given to analyse the results analytically, as far as possible, to elucidate the role of the interaction parameters involved in the predictions.

  11. Writing electronic ferromagnetic states in a high-temperature paramagnetic nuclear spin system

    E-print Network

    D. O. Soares-Pinto; J. Teles; A. M. Souza; E. R. deAzevedo; R. S. Sarthour; T. J. Bonagamba; M. S. Reis; I. S. Oliveira

    2011-06-30

    In this paper we use the Nuclear Magnetic Resonance (NMR) to write eletronic states of a ferromagnetic system into a high-temperature paramagnetic nuclear spins. Through the control of phase and duration of radiofrequency pulses we set the NMR density matrix populations, and apply the technique of quantum state tomography to experimentally obtain the matrix elements of the system, from which we calculate the temperature dependence of magnetization for different magnetic fields. The effects of the variation of temperature and magnetic field over the populations can be mapped in the angles of spins rotations, carried out by the RF pulses. The experimental results are compared to the Brillouin functions of ferromagnetic ordered systems in the mean field approximation for two cases: the mean field is given by (i) $B=B_0+\\lambda M$ and (ii) $B=B_0+\\lambda M + \\lambda^\\prime M^3$, where $B_0$ is the external magnetic field, and $\\lambda, \\lambda^\\prime$ are mean field parameters. The first case exhibits second order transition, whereas the second case has first order transition with temperature hysteresis. The NMR simulations are in good agreement with the magnetic predictions.

  12. Nuclear spin relaxation of sodium cations in bacteriophage Pf1 solutions D. N. Sobieski, N. R. Krueger, S. Vyas,a

    E-print Network

    Augustine, Mathew P.

    Nuclear spin relaxation of sodium cations in bacteriophage Pf1 solutions D. N. Sobieski, N. R The nuclear magnetic resonance NMR spectra for the I=3/2 23 Na cation dissolved into filamentous bacteriophage

  13. Spin projection in the shell model Monte Carlo method and the spin distribution of nuclear level densities

    E-print Network

    Y. Alhassid; S. Liu; H. Nakada

    2006-07-27

    We introduce spin projection methods in the shell model Monte Carlo approach and apply them to calculate the spin distribution of level densities for iron-region nuclei using the complete $(pf+g_{9/2})$-shell. We compare the calculated distributions with the spin-cutoff model and extract an energy-dependent moment of inertia. For even-even nuclei and at low excitation energies, we observe a significant suppression of the moment of inertia and odd-even staggering in the spin dependence of level densities.

  14. Relativistic four-component calculations of indirect nuclear spin-spin couplings with efficient evaluation of the exchange-correlation response kernel

    NASA Astrophysics Data System (ADS)

    K?ístková, Anežka; Komorovsky, Stanislav; Repisky, Michal; Malkin, Vladimir G.; Malkina, Olga L.

    2015-03-01

    In this work, we report on the development and implementation of a new scheme for efficient calculation of indirect nuclear spin-spin couplings in the framework of four-component matrix Dirac-Kohn-Sham approach termed matrix Dirac-Kohn-Sham restricted magnetic balance resolution of identity for J and K, which takes advantage of the previous restricted magnetic balance formalism and the density fitting approach for the rapid evaluation of density functional theory exchange-correlation response kernels. The new approach is aimed to speedup the bottleneck in the solution of the coupled perturbed equations: evaluation of the matrix elements of the kernel of the exchange-correlation potential. The performance of the new scheme has been tested on a representative set of indirect nuclear spin-spin couplings. The obtained results have been compared with the corresponding results of the reference method with traditional evaluation of the exchange-correlation kernel, i.e., without employing the fitted electron densities. Overall good agreement between both methods was observed, though the new approach tends to give values by about 4%-5% higher than the reference method. On the average, the solution of the coupled perturbed equations with the new scheme is about 8.5 times faster compared to the reference method.

  15. Energy-Level Related Nuclear-Spin Effects and Super-Hyperfine Spectral Patterns: how Molecules do Self-Nmr

    NASA Astrophysics Data System (ADS)

    Harter, William; Mitchell, Justin

    2009-06-01

    At several points in his defining works on molecular spectroscopy, Herzberg notes that ``because nuclear moments ldots are so very slight ldots transitions between species ldots are very strictly forbiddenldots '' Herzberg's most recent statement of such selection rules pertained to spherical top spin-species. It has since been shown that spherical top species (as well as those of lower symmetry molecules) converge exponentially with momentum quanta J and K to degenerate level clusters wherein even ``very slight'' nuclear fields and moments cause pervasive resonance and total spin species mixing. Ultra-high resolution spectra of Borde, et .al and Pfister et .al shows how SF_6 and SiF_4 Fluorine nuclear spin levels rearrange from total-spin multiplets to NMR-like patterns as their superfine structure converges. Similar super-hyperfine effects are anticipated for lower symmetry molecules exhibiting converging superfine level-clusters. Examples include PH_3 molecules and asymmetric tops. Following this we consider models that treat nuclear spins as coupled rotors undergoing generalized Hund-case transitions from spin-lab-momentum coupling to various spin-rotor correlations. G. A. Herzberg, Electronic Spectra of Polyatomic Molecules, (Von Norstrand Rheinhold 1966) p. 246. W G. Harter and C. W Patterson, Phys. Rev. A 19, 2277 (1979) W. G. Harter, Phys. Rev. A 24, 192 (1981). Ch. J. Borde, J. Borde, Ch. Breant, Ch. Chardonnet, A. Van Lerberghe, and Ch. Salomon, in Laser Spectroscopy VII, T. W Hensch and Y. R. Shen, eds. (Springer-Verlag, Berlin, 1985). O. Pfister, F. Guernet, G. Charton, Ch. Chardonnet, F. Herlemont, and J. Legrand, J. Opt. Soc. Am. B 10, 1521 (1993). O. Pfister, Ch. Chardonnet, and Ch. J. Bordè, Phys. Rev. Lett. 76, 4516 (1996) S. N. Yurchenko, W. Thiel, S. Patchkovskii, and P. Jensen, Phys. Chem. Chem. Phys.7, 573 (2005)

  16. Solid state nuclear magnetic resonance with magic-angle spinning and dynamic nuclear polarization below 25 K

    PubMed Central

    Thurber, Kent R.; Potapov, Alexey; Yau, Wai-Ming; Tycko, Robert

    2012-01-01

    We describe an apparatus for solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS) at 20–25 K and 9.4 Tesla. The MAS NMR probe uses helium to cool the sample space and nitrogen gas for MAS drive and bearings, as described earlier (Thurber et al., J. Magn. Reson. 2008) [1], but also includes a corrugated waveguide for transmission of microwaves from below the probe to the sample. With a 30 mW circularly polarized microwave source at 264 GHz, MAS at 6.8 kHz, and 21 K sample temperature, greater than 25-fold enhancements of cross-polarized 13C NMR signals are observed in spectra of frozen glycerol/water solutions containing the triradical dopant DOTOPA-TEMPO when microwaves are applied. As demonstrations, we present DNP-enhanced one-dimensional and two-dimensional 13C MAS NMR spectra of frozen solutions of uniformly 13C-labeled L-alanine and melittin, a 26-residue helical peptide that we have synthesized with four uniformly 13C-labeled amino acids. PMID:23238592

  17. Nuclear Jacobi and Poincaré transitions at high spins and temperatures: Account of dynamic effects and large-amplitude motion

    NASA Astrophysics Data System (ADS)

    Mazurek, K.; Dudek, J.; Maj, A.; Rouvel, D.

    2015-03-01

    We present a theoretical analysis of the competition between the so-called nuclear Jacobi and Poincaré shape transitions as a function of spin at high temperatures. The latter condition implies the method of choice, a realistic version of the nuclear liquid drop model, here the Lublin-Strasbourg drop model. We address specifically the fact that the Jacobi and Poincaré shape transitions are accompanied by the flattening of the total nuclear energy landscape as a function of the relevant deformation parameters, which enforces large-amplitude oscillation modes that need to be taken into account. For that purpose we introduce an approximate form of the collective Schrödinger equation whose solutions are used to calculate the most probable deformations associated with the nuclear Jacobi and Poincaré transitions. We discuss selected aspects of the new description focusing on the critical-spin values for both types of these transitions.

  18. Nuclear Spin of H_3^+ and H_2 in Dense Molecular Clouds

    NASA Astrophysics Data System (ADS)

    Crabtree, Kyle N.; McCall, Benjamin J.

    2012-06-01

    The ortho:para ratio of H_2 is a critical parameter for deuterium fractionation in cold, dense quiescent cores. The dominant reservoir for interstellar deuterium is in the inert molecule HD, but the exothermic reaction H_3^+ + HD ? H_2D^+ + H_2 + 220 K (and H_2D^+ + HD, etc.) can yield highly reactive species capable of distributing deuterium to other molecules. The barrier to the reverse reaction, however, can be overcome even at temperatures below 10 K when ortho-H_2 (o-H_2) reacts with H_2D^+ (or D_2H^+, D_3^+), as ortho-H_2 possesses ˜170 K of internal rotational energy in its ground state. Recent modeling work has demonstrated the importance of o-H_2 in cold, dense, highly depleted cores using a chemical network that includes all nuclear spin modifications of H_3^+, H_2, and their isotopologues, but the initial o-H_2 fraction is taken as a parameter in the model. Observationally or computationally constraining this quantity would aid in understanding deuterium fractionation in dense cores. To learn about the initial o-H_2 fraction in a cold core, we have modeled the chemistry of non-depleted dense interstellar clouds from which cold cores are thought to form. A simplified gas-phase chemical network consisting of 28 species and ˜170 reactions is combined with a physical model of a dense cloud, including time-dependent physical conditions. Included in the network are the nuclear spin modifications of H_2, H_2^+, and H_3^+, as well as nuclear spin dependent rate coefficients for the thermalization reactions H_2 + H^+ and H_3^+ + H_2. By modeling the time-dependent chemistry, we find that the ortho:para ratio of H_2 requires 10^7-10^8 years to reach steady state under ``standard'' dense cloud conditions, which is at least on the order of the cloud lifetime. The timescale depends on the ionization rate, the rate coefficients of the various H_3^+ + H_2 reactions, and the relative abundances of H_3^+ and H^+, but is largely insensitive to the total density and temperature. Even at steady state, the o-H_2 fraction is calculated to be >0.5% at 10 K, which is several orders of magnitude above its value at thermodynamic equilibrium. The prospects for using observations of the ortho:para ratio of H_3^+ as a probe of the H_2 ortho:para ratio will be discussed.

  19. Indirect two-dimensional J spectroscopy: Measurement of proton multiplet structure via carbon-13 signals

    NASA Astrophysics Data System (ADS)

    Morris, Gareth A.

    The problem of determining proton-proton couplings in overcrowded spectra can, in favorable cases, be solved using two-dimensional NMR spectroscopy to correlate proton multiplet structure with carbon-13 chemical shifts. The method proposed is based on a recent experiment described by Bodenhausen, modified to suppress heteronuclear couplings. Spectra are presented illustrating the application of the new technique to the sugars sucrose and raffinose.

  20. The Low-temperature Nuclear Spin Equilibrium of H+ 3 in Collisions with H2

    NASA Astrophysics Data System (ADS)

    Grussie, F.; Berg, M. H.; Crabtree, K. N.; Gärtner, S.; McCall, B. J.; Schlemmer, S.; Wolf, A.; Kreckel, H.

    2012-11-01

    Recent observations of H2 and H+ 3 in diffuse interstellar sightlines revealed a difference in the nuclear spin excitation temperatures of the two species. This discrepancy comes as a surprise, as H+ 3 and H2 should undergo frequent thermalizing collisions in molecular clouds. Non-thermal behavior of the fundamental H+ 3/H2 collision system at low temperatures was considered as a possible cause for the observed irregular populations. Here, we present measurements of the steady-state ortho/para ratio of H+ 3 in collisions with H2 molecules in a temperature-variable radiofrequency ion trap between 45 and 100 K. The experimental results are close to the expected thermal outcome and they agree very well with a previous micro-canonical model. We briefly discuss the implications of the experimental results for the chemistry of the diffuse interstellar medium.

  1. The Low-Temperature Nuclear Spin Equilibrium of H3+ in Collisions with H2

    E-print Network

    Grussie, F; Crabtree, K N; Gaertner, S; McCall, B J; Schlemmer, S; Wolf, A; Kreckel, H

    2012-01-01

    Recent observations of H2 and H3+ in diffuse interstellar sightlines revealed a difference in the nuclear spin excitation temperatures of the two species. This discrepancy comes as a surprise, as H3+ and H2 should undergo frequent thermalizing collisions in molecular clouds. Non-thermal behavior of the fundamental H3+ / H2 collision system at low temperatures was considered as a possible cause for the observed irregular populations. Here, we present measurements of the steady-state ortho/para ratio of H3+ in collisions with H2 molecules in a temperature-variable radiofrequency ion trap between 45-100 K. The experimental results are close to the expected thermal outcome and they agree very well with a previous micro-canonical model. We briefly discuss the implications of the experimental results for the chemistry of the diffuse interstellar medium.

  2. A Statistical Model for Describing Spectral Diffusion Effects in Electron Spin Echo (ESE) and Electron Nuclear Double Resonance (ENDOR) Experiments

    Microsoft Academic Search

    M. Franke; W. Windsch

    1976-01-01

    A statistical model for an EPR line broadened by dipolar electron-nuclear interaction is proposed. This makes it possible for the effect of spectral diffusion on the width and intensity of ENDOR signals to be determined from electron spin echo experiments. In this paper, various ENDOR mechanisms are discussed in addition to a calculation of the variation in both Boltzmann factor

  3. Fast radio-frequency amplitude modulation in multiple-quantum magic-angle-spinning nuclear magnetic resonance: Theory and experiments

    E-print Network

    Frydman, Lucio

    Fast radio-frequency amplitude modulation in multiple-quantum magic-angle-spinning nuclear magnetic of this experiment has been the poor efficiency of the radio-frequency pulses used in converting multiple-modulated radio-frequency pulses, and which can yield substantial signal and even resolution enhancements over

  4. Magnetization transfer modes in scalar-coupled spin systems investigated by selective two-dimensional nuclear magnetic resonance exchange experiments

    Microsoft Academic Search

    Lorenzo di Bari; Jozef Kowalewski; Geoffrey Bodenhausen

    1990-01-01

    Longitudinal nuclear magnetic relaxation in coupled two-spin systems is discussed in terms of magnetization transfermodes, a generalization of the magnetization modes commonly used in the discussion of one-dimensional NMR relaxation experiments. The symmetry properties of the transfer modes and their relationship to the elements of the usual Redfield relaxation matrix are discussed. Experimental strategies for measuring the amplitudes of the

  5. Nuclear spin relaxation of {sup 129}Xe due to persistent xenon dimers

    SciTech Connect

    Berry-Pusey, B. N.; Anger, B. C.; Laicher, G.; Saam, B. [Department of Physics, University of Utah, Salt Lake City, Utah 84112-0830 (United States)

    2006-12-15

    We have measured longitudinal nuclear relaxation rates of {sup 129}Xe in Xe-N{sub 2} mixtures at densities below 0.5 amagats in a magnetic field of 8.0 T. We find that intrinsic spin relaxation in this regime is principally due to fluctuations in the intramolecular spin-rotation (SR) and chemical-shift-anisotropy (CSA) interactions, mediated by the formation of {sup 129}Xe-Xe persistent dimers. Our results are consistent with previous work done in one case at much lower applied fields where the CSA interaction is negligible and in another case at much higher gas densities where transient xenon dimers mediate the interactions. We have verified that a large applied field suppresses the persistent-dimer mechanism, consistent with standard relaxation theory, allowing us to measure room-temperature gas-phase relaxation times T{sub 1} for {sup 129}Xe greater than 25 h at 8.0 T. These data also yield a maximum possible low-field T{sub 1} for pure xenon gas at room temperature of 5.45{+-}0.2 h. The coupling strengths for the SR and CSA interactions that we extract are in fair agreement with estimates based both on previous experimental work and on ab initio calculations. Our results have potential implications for the production and storage of large quantities of hyperpolarized {sup 129}Xe for use in various applications.

  6. Test of Parity-Conserving Time-Reversal Invariance Using Polarized Neutrons and Nuclear Spin Aligned Holmium

    E-print Network

    P. R. Huffman; N. R. Roberson; W. S. Wilburn; C. R. Gould; D. G. Haase; C. D. Keith; B. W. Raichle; M. L. Seely; J. R. Walston

    1996-05-24

    A test of parity-conserving, time-reversal non-invariance (PC TRNI) has been performed in 5.9 MeV polarized neutron transmission through nuclear spin aligned holmium. The experiment searches for the T-violating five-fold correlation via a double modulation technique - flipping the neutron spin while rotating the alignment axis of the holmium. Relative cross sections for spin-up and spin-down neutrons are found to be equal to within $1.2 \\times 10^{-5}$ (80\\% confidence). This is a two order of magnitude improvement compared to traditional detailed balance studies of time reversal, and represents the most precise test of PC TRNI in a dynamical process.

  7. Nuclear spin imaging with hyperpolarized nuclei created by brute force method

    NASA Astrophysics Data System (ADS)

    Tanaka, Masayoshi; Kunimatsu, Takayuki; Fujiwara, Mamoru; Kohri, Hideki; Ohta, Takeshi; Utsuro, Masahiko; Yosoi, Masaru; Ono, Satoshi; Fukuda, Kohji; Takamatsu, Kunihiko; Ueda, Kunihiro; Didelez, Jean-P.; Prossati, Giorgio; de Waard, Arlette

    2011-05-01

    We have been developing a polarized HD target for particle physics at the SPring-8 under the leadership of the RCNP, Osaka University for the past 5 years. Nuclear polarizaton is created by means of the brute force method which uses a high magnetic field (~17 T) and a low temperature (~ 10 mK). As one of the promising applications of the brute force method to life sciences we started a new project, "NSI" (Nuclear Spin Imaging), where hyperpolarized nuclei are used for the MRI (Magnetic Resonance Imaging). The candidate nuclei with spin ½hslash are 3He, 13C, 15N, 19F, 29Si, and 31P, which are important elements for the composition of the biomolecules. Since the NMR signals from these isotopes are enhanced by orders of magnitudes, the spacial resolution in the imaging would be much more improved compared to the practical MRI used so far. Another advantage of hyperpolarized MRI is that the MRI is basically free from the radiation, while the problems of radiation exposure caused by the X-ray CT or PET (Positron Emission Tomography) cannot be neglected. In fact, the risk of cancer for Japanese due to the radiation exposure through these diagnoses is exceptionally high among the advanced countries. As the first step of the NSI project, we are developing a system to produce hyperpolarized 3He gas for the diagnosis of serious lung diseases, for example, COPD (Chronic Obstructive Pulmonary Disease). The system employs the same 3He/4He dilution refrigerator and superconducting solenoidal coil as those used for the polarized HD target with some modification allowing the 3He Pomeranchuk cooling and the following rapid melting of the polarized solid 3He to avoid the depolarization. In this report, the present and future steps of our project will be outlined with some latest experimental results.

  8. Optically addressable nuclear spins in a solid with a six-hour coherence time

    NASA Astrophysics Data System (ADS)

    Zhong, Manjin; Hedges, Morgan P.; Ahlefeldt, Rose L.; Bartholomew, John G.; Beavan, Sarah E.; Wittig, Sven M.; Longdell, Jevon J.; Sellars, Matthew J.

    2015-01-01

    Space-like separation of entangled quantum states is a central concept in fundamental investigations of quantum mechanics and in quantum communication applications. Optical approaches are ubiquitous in the distribution of entanglement because entangled photons are easy to generate and transmit. However, extending this direct distribution beyond a range of a few hundred kilometres to a worldwide network is prohibited by losses associated with scattering, diffraction and absorption during transmission. A proposal to overcome this range limitation is the quantum repeater protocol, which involves the distribution of entangled pairs of optical modes among many quantum memories stationed along the transmission channel. To be effective, the memories must store the quantum information encoded on the optical modes for times that are long compared to the direct optical transmission time of the channel. Here we measure a decoherence rate of 8 × 10-5 per second over 100 milliseconds, which is the time required for light transmission on a global scale. The measurements were performed on a ground-state hyperfine transition of europium ion dopants in yttrium orthosilicate (151Eu3+:Y2SiO5) using optically detected nuclear magnetic resonance techniques. The observed decoherence rate is at least an order of magnitude lower than that of any other system suitable for an optical quantum memory. Furthermore, by employing dynamic decoupling, a coherence time of 370 +/- 60 minutes was achieved at 2 kelvin. It has been almost universally assumed that light is the best long-distance carrier for quantum information. However, the coherence time observed here is long enough that nuclear spins travelling at 9 kilometres per hour in a crystal would have a lower decoherence with distance than light in an optical fibre. This enables some very early approaches to entanglement distribution to be revisited, in particular those in which the spins are transported rather than the light.

  9. Optically addressable nuclear spins in a solid with a six-hour coherence time.

    PubMed

    Zhong, Manjin; Hedges, Morgan P; Ahlefeldt, Rose L; Bartholomew, John G; Beavan, Sarah E; Wittig, Sven M; Longdell, Jevon J; Sellars, Matthew J

    2015-01-01

    Space-like separation of entangled quantum states is a central concept in fundamental investigations of quantum mechanics and in quantum communication applications. Optical approaches are ubiquitous in the distribution of entanglement because entangled photons are easy to generate and transmit. However, extending this direct distribution beyond a range of a few hundred kilometres to a worldwide network is prohibited by losses associated with scattering, diffraction and absorption during transmission. A proposal to overcome this range limitation is the quantum repeater protocol, which involves the distribution of entangled pairs of optical modes among many quantum memories stationed along the transmission channel. To be effective, the memories must store the quantum information encoded on the optical modes for times that are long compared to the direct optical transmission time of the channel. Here we measure a decoherence rate of 8 × 10(-5) per second over 100 milliseconds, which is the time required for light transmission on a global scale. The measurements were performed on a ground-state hyperfine transition of europium ion dopants in yttrium orthosilicate ((151)Eu(3+):Y2SiO5) using optically detected nuclear magnetic resonance techniques. The observed decoherence rate is at least an order of magnitude lower than that of any other system suitable for an optical quantum memory. Furthermore, by employing dynamic decoupling, a coherence time of 370 ± 60 minutes was achieved at 2 kelvin. It has been almost universally assumed that light is the best long-distance carrier for quantum information. However, the coherence time observed here is long enough that nuclear spins travelling at 9 kilometres per hour in a crystal would have a lower decoherence with distance than light in an optical fibre. This enables some very early approaches to entanglement distribution to be revisited, in particular those in which the spins are transported rather than the light. PMID:25567283

  10. Fractionated Mercury Isotopes in Fish: The Effects of Nuclear Mass, Spin, and Volume

    NASA Astrophysics Data System (ADS)

    Das, R.; Odom, A. L.

    2007-12-01

    Mercury is long known as a common environmental contaminant. In methylated form it is even more toxic and the methylation process is facilitated by microbial activities. Methyl mercury easily crosses cell membrane and accumulates in soft tissues of fishes and finally biomagnifies with increasing trophic levels. Natural variations in the isotopic composition of mercury have been reported and such variations have emphasized mass dependent fractionations, while theory and laboratory experiments indicate that mass-independent isotopic fractionation (MIF) effects are likely to be found as well. This study focuses on the MIF of mercury isotopes in the soft tissues of fishes. Samples include both fresh water and marine fish, from different continents and oceans. Approximately 1 gm of fish soft tissue was dissolved in 5 ml of conc. aqua regia for 24 hrs and filtered through a ¬¬¬100 ?m filter paper and diluted with DI water. Hg is measured as a gaseous phase generated by reduction of the sample with SnCl2 in a continuous- flow cold-vapor generator connected to a Thermo-Finnigan Neptune MC-ICPMS. To minimize instrumental fractionation isotope ratios were measured by sample standard bracketing and reported as ?‰ relative to NIST SRM 3133 Hg standard where ?AHg = [(A Hg/202Hg)sample/(A Hg/202Hg)NIST313] -1 ×1000‰. In this study we have measured the isotope ratios 198Hg/202Hg, 199Hg/202Hg, 200Hg/202Hg, 201Hg/202Hg and 204Hg/202Hg. In all the fish samples ?198Hg, ?200Hg, ?202Hg, ?204Hg define a mass- dependent fractionation sequence, where as the ?199Hg and ?201Hg depart from the mass- dependent fractionation line and indicate an excess of the odd-N isotopes. The magnitude of the deviation (?AHg where A=199 or 201) as obtained by difference between the measured ?199Hg and ?201Hg of the samples and the value obtained by linear scaling defined by the even-N isotopes ranges from approximately 0.2 ‰ to 3‰. The ratios of ?199Hg /?201Hg range from 0.8 to 1.3, and thus more than one mass-independent isotope effect is inferred. MIF of mercury can be caused by the nuclear volume effect. Schauble, 2007 has calculated nuclear volume fractionation scaling factors for a number of common mercury chemical species in equilibrium with Hg° vapor. From his calculations the nuclear field shift effect is larger in ?199Hg than in ?201Hg by approximately a factor of two. The predominant mercury chemical species in fish is methylmercury cysteine. From the experimental studies of Buchachenko and others (2004) on the reaction of methylmercury chloride with creatine kinase it seems reasonable to predicted that the thiol functional groups of cysteine gets enriched in 199Hg and 201Hg. Here the magnetic isotope effect (MIE) produces a kinetic partial separation of isotopes with non-zero nuclear spin quantum numbers from the even-N isotopes. The ratio of enrichment of ?201Hg /?199Hg is predicted from theory to be 1.11, which is the ratio of the magnetic moments of 199Hg and 201Hg. Because mercury possesses two odd-N isotopes, it is possible to detect and evaluate the effects of two distinct, mass-independent isotope fractionating processes. From the data obtained on fish samples, we can deconvolute the contributions of the isotope effects of nuclear mass, spin and volume. For these samples the role of spin or the magnetic isotope effect is the most dominant.

  11. Chemical characterization of pigment gallstones using /sup 13/C nuclear magnetic resonance analysis

    SciTech Connect

    Woolfenden, W.R. (Univ. of Utah, Salt Lake City); Grant, D.M.; Straight, R.C.; Englert, E. Jr.

    1982-07-30

    The unique ability of Carbon-13 nuclear magnetic resonance analysis with cross polarization/magic angle spinning techniques to investigate chemical structures of solids is used to probe the chemical characteristics of several gallstone types. New pulse program techniques are used to distinguish various carbon atoms in studying the polymeric nature of the black bilirubinoid pigment of pigment gallstones. Evidence for the involvement of the carboxyl group and noninvolvement of vinyl groups of bilirubinoids in the polymeric bond formation is presented. Conjugated bilirubin structures are found to be present in some solid residues from pigment stones extracted with acidic methanol/chloroform.

  12. Optical detection of anisotropic g-factor and nuclear spin polarization in a single CdTe quantum well

    NASA Astrophysics Data System (ADS)

    Yan, Li-Ping; Kurosawa, Masahiro; Hsu, Wei-Ting; Chang, Wen-Hao; Adachi, Satoru

    2015-03-01

    Longitudinal and in-plane electron g-factors, and a nuclear spin polarization (NSP) have been evaluated precisely in a CdTe/Cd0.85Mg0.15Te single quantum well by using the time-resolved Kerr rotation and double lock-in detection techniques. Resident electron spin polarization (RESP) was formed via the negative trion formation and recombination, and RESP gave rise to NSP in an oblique magnetic field configuration. We observed the effective nuclear field of a few mT which was weak compared with that in III–V semiconductor nanostructures as expected, but the nuclear field can be converted to the maximal NSP of 12% in Faraday geometry.

  13. A new type of nuclear collective motion - the spin scissors mode

    E-print Network

    E. B. Balbutsev; I. V. Molodtsova; P. Schuck

    2013-01-11

    The coupled dynamics of low lying modes and various giant resonances are studied with the help of the Wigner Function Moments method on the basis of Time Dependent Hartree-Fock equations in the harmonic oscillator model including spin-orbit potential plus quadrupole-quadrupole and spin-spin residual interactions. New low lying spin dependent modes are analyzed. Special attention is paid to the spin scissors mode.

  14. Dynamic-angle spinning and double rotation of quadrupolar nuclei

    SciTech Connect

    Mueller, K.T. (Lawrence Berkeley Lab., CA (United States) California Univ., Berkeley, CA (United States). Dept. of Chemistry)

    1991-07-01

    Nuclear magnetic resonance (NMR) spectroscopy of quadrupolar nuclei is complicated by the coupling of the electric quadrupole moment of the nucleus to local variations in the electric field. The quadrupolar interaction is a useful source of information about local molecular structure in solids, but it tends to broaden resonance lines causing crowding and overlap in NMR spectra. Magic- angle spinning, which is routinely used to produce high resolution spectra of spin-{1/2} nuclei like carbon-13 and silicon-29, is incapable of fully narrowing resonances from quadrupolar nuclei when anisotropic second-order quadrupolar interactions are present. Two new sample-spinning techniques are introduced here that completely average the second-order quadrupolar coupling. Narrow resonance lines are obtained and individual resonances from distinct nuclear sites are identified. In dynamic-angle spinning (DAS) a rotor containing a powdered sample is reoriented between discrete angles with respect to high magnetic field. Evolution under anisotropic interactions at the different angles cancels, leaving only the isotropic evolution of the spin system. In the second technique, double rotation (DOR), a small rotor spins within a larger rotor so that the sample traces out a complicated trajectory in space. The relative orientation of the rotors and the orientation of the larger rotor within the magnetic field are selected to average both first- and second-order anisotropic broadening. The theory of quadrupolar interactions, coherent averaging theory, and motional narrowing by sample reorientation are reviewed with emphasis on the chemical shift anisotropy and second-order quadrupolar interactions experienced by half-odd integer spin quadrupolar nuclei. The DAS and DOR techniques are introduced and illustrated with application to common quadrupolar systems such as sodium-23 and oxygen-17 nuclei in solids.

  15. High-fidelity gate operations with the coupled nuclear and electron spins of a nitrogen-vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Everitt, Mark S.; Devitt, Simon; Munro, W. J.; Nemoto, Kae

    2014-05-01

    In this article we investigate the dynamics of a single negatively charged nitrogen-vacancy center (NV-) coupled to the spin of the nucleus of a 15-nitrogen atom and show that high-speed, high-fidelity gate operations are possible without the need for complicated composite pulse sequences. These operations include both the electron and nuclear spin rotations, as well as an entangling gate between them. These are the primitive gates one will need within a quantum node of a distributed communication network.

  16. Electron-nuclear spin control in charged semiconductor quantum dots by electrical currents through micro-coils

    NASA Astrophysics Data System (ADS)

    Kim, Jungtaek; Puls, J.; Chen, Y. S.; Bacher, G.; Henneberger, F.

    2010-04-01

    We have fabricated micrometer-sized single-turn coils on top of charged CdSe/ZnSe quantum dot heterostructures by lithographical techniques. Current injection creates magnetic fields in the some 10 mT range, strong enough to modulate the hyperfine interaction. The very low coil inductance allows for generation of fast field transients. We demonstrate local control of the resident electron spin as well as read-out of the nuclear spin state on the 10 ns time scale by electrical current pulses.

  17. Carbon-13 nuclear magnetic resonance studies of metabolism in Crithidia fasciculata

    E-print Network

    McCloskey, Diane Elizabeth

    1986-01-01

    Chairman of Advisory Committee: Dr. A. I. Scott Pathways of metabolism utilized by the mosquito parasite Crithidia fasciculara have been investigated using "C NMR spectroscopy. Analysis of the complex "C-"C coupling patterns derived from uniformly... LIST OF SCHEMES LIST OF FIGURES INTRODUCTION MATERIALS AND METHODS V1 V111 15 Growth of Crithidia Fascicuiara Metabolic Experiments Substrates NMR Spectroscopy Analytical Methods RESULTS AND DISCUSSION 15 IB 20 20 21 24 Aerobic...

  18. Carbon-13 nuclear magnetic resonance study of mixed micelles. Variation of interchain distances and conformational equilibria

    SciTech Connect

    De Weerd, R.J.E.M.; De Hann, J.W.; Van de Ven, L.J.M.; Achten, M.; Buck, H.M.

    1982-06-24

    Observed /sup 13/C NMR chemical shift changes with respect to their single micelles upon mixed-micelle formation of potassium dodecanoate and short-chain potassium carboxylates (hexanoate up to and including decanoate) are described in all but one case to increasing distances between the apolar ends of the long amphiphile chains as compared with its single micelle. Only for dodecanoate-hexanoate micellar systems can a different conformational equilibrium of the dodecanoate chain not be excluded. Furthermore, recently observed solvent effects upon mixing of n-alkanes of different chain lengths are compared with both the decanoate and nonanoate chemical shift changes upon mixing with the dodecanoate amphiphiles. This leads to the conclusion that the former detergents are mainly subject to increased intermolecular chain packing. Observed effects for the octanoate and heptanoate are not as pronounced, and these surfactants should be considered as borderline cases, while the hexanoate undergoes conformational changes toward more extended forms. 46 references.

  19. Suppression of nuclear spin diffusion at a GaAs/AlGaAs interface measured with a single quantum dot nano-probe

    E-print Network

    A. E. Nikolaenko; E. A. Chekhovich; M. N. Makhonin; I. W. Drouzas; A. B. Vankov; J. Skiba-Szymanska; M. S. Skolnick; P. Senellart; A. Lemaitre; A. I. Tartakovskii

    2009-01-15

    Nuclear spin polarization dynamics are measured in optically pumped individual GaAs/AlGaAs interface quantum dots by detecting the time-dependence of the Overhauser shift in photoluminescence (PL) spectra. Long nuclear polarization decay times of ~ 1 minute have been found indicating inefficient nuclear spin diffusion from the GaAs dot into the surrounding AlGaAs matrix in externally applied magnetic field. A spin diffusion coefficient two orders lower than that previously found in bulk GaAs is deduced.

  20. Microwave Field Distribution in a Magic Angle Spinning Dynamic Nuclear Polarization NMR Probe

    PubMed Central

    Nanni, Emilio A.; Barnes, Alexander B.; Matsuki, Yoh; Woskov, Paul P.; Corzilius, Björn; Griffin, Robert G.; Temkin, Richard J.

    2011-01-01

    We present a calculation of the microwave field distribution in a magic angle spinning (MAS) probe utilized in dynamic nuclear polarization (DNP) experiments. The microwave magnetic field (B1S) profile was obtained from simulations performed with the High Frequency Structure Simulator (HFSS) software suite, using a model that includes the launching antenna, the outer Kel-F stator housing coated with Ag, the RF coil, and the 4 mm diameter sapphire rotor containing the sample. The predicted average B1S field is 13µT/W1/2, where S denotes the electron spin. For a routinely achievable input power of 5 W the corresponding value is ? SB1S = 0.84 MHz. The calculations provide insights into the coupling of the microwave power to the sample, including reflections from the RF coil and diffraction of the power transmitted through the coil. The variation of enhancement with rotor wall thickness was also successfully simulated. A second, simplified calculation was performed using a single pass model based on Gaussian beam propagation and Fresnel diffraction. This model provided additional physical insight and was in good agreement with the full HFSS simulation. These calculations indicate approaches to increasing the coupling of the microwave power to the sample, including the use of a converging lens and fine adjustment of the spacing of the windings of the RF coil. The present results should prove useful in optimizing the coupling of microwave power to the sample in future DNP experiments. Finally, the results of the simulation were used to predict the cross effect DNP enhancement (?) vs. ?1S/(2?) for a sample of 13C-urea dissolved in a 60:40 glycerol/water mixture containing the polarizing agent TOTAPOL; very good agreement was obtained between theory and experiment. PMID:21382733

  1. Shell-model study of spin modes in nuclei and nuclear forces

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio; Otsuka, Takaharu; Honma, Michio; Tsunoda, Naofumi

    2015-02-01

    Spin-dependent modes in nuclei are studied by shell-model method with the use of new shell-model Hamiltonians which properly take into account important roles of tensor interactions. New Hamiltonians can describe spin degrees of freedom in nuclei remarkably well. Nuclear weak processes at stellar environments are investigated based on these successes. New neutrino-nucleus reaction cross sections on 12C are applied to light-element synthesis in supernova explosions. The production rate for 11B/7Li is pointed out to be useful to determine v-oscillation parameters, in particular, v-mass hierarchy. New e-capture rates in Ni isotopes are obtained and implications for element synthesis are discussed. The monopole-based universal interaction is applied to study structure of p-sd shell nuclei and 40Ar as well as v-induced reactions on 40Ar. Repulsive corrections in the isospin T=1 monopoles are shown to be important for proper shell evolutions in neutron-rich carbon isotopes. The repulsive correction is pointed out to be due to three-body forces, in particular, the Fujita-Miyazawa force. Roles of the three-body forces on the shell evolution of neutron-rich calcium isotopes, the closed- shell nature of 48 Ca and M1 transition in 48 Ca are studied on top of the two-body G-matrix obtained by including core-polarization effects in larger spaces (<=24hslash?). Effects of the inclusion of g9/2-shell are also discussed.

  2. Nuclear magnetic resonance relaxivities: investigations of ultrahigh-spin lanthanide clusters from 10 MHz to 1.4 GHz.

    PubMed

    Machado, Julyana R; Baniodeh, Amer; Powell, Annie K; Luy, Burkhard; Krämer, Steffen; Guthausen, Gisela

    2014-11-10

    Paramagnetic relaxation enhancement is often explored in magnetic resonance imaging in terms of contrast agents and in biomolecular nuclear magnetic resonance (NMR) spectroscopy for structure determination. New ultrahigh-spin clusters are investigated with respect to their NMR relaxation properties. As their molecular size and therefore motional correlation times as well as their electronic properties differ significantly from those of conventional contrast agents, questions about a comprehensive characterization arise. The relaxivity was studied by field-dependent longitudinal and transverse NMR relaxometry of aqueous solutions containing Fe(III)(10)Dy(III)(10) ultrahigh-spin clusters (spin ground state 100/2). The high-field limit was extended to 32.9 T by using a 24 MW resistive magnet and an ultrahigh-frequency NMR setup. Interesting relaxation dispersions were observed; the relaxivities increase up to the highest available fields, which indicates a complex interplay of electronic and molecular correlation times. PMID:25115895

  3. Observation of satellite signals due to scalar coupling to spin-1\\/2 isotopes in solid-state nuclear magnetic resonance spectroscopy

    Microsoft Academic Search

    Adriana Iuga; Dinu Iuga; Albert R. Cross; Michael Gerken; Paul Hazendonk

    2007-01-01

    A method is introduced to select the signal from a spin-1\\/2 nucleus I specifically bound to another spin-1\\/2 nucleus S for solid-state magic angle spinning nuclear magnetic resonance (NMR) spectroscopy via correlation through the heteronuclear J coupling. This experiment is analogous to the bilinear rotation decoupling (BIRD) sequence in liquid-state NMR spectroscopy which selects for signals from 1H directly bound

  4. Ground state moments and spins of neutron-rich K and Al isotopes as probes for changes in nuclear structure

    NASA Astrophysics Data System (ADS)

    Neyens, G.

    2013-07-01

    This contribution focusses on recent measurements of nuclear moments and spins using two complementary methods. The ground state magnetic moments and spins of the exotic isotopes 49,51K have been measured at the ISOLDE facility at CERN using bunched-beam high-resolution collinear laser spectroscopy. The re-inversion of the ground state spin from I = 1/2 in 47,49K back to the normal I = 3/2 in 51K has been established. At GANIL (Caen, France) the quadrupole moment of the 33Al ground state has been measured using the continuous-beam ?-nuclear magnetic resonance method applied to a spin-polarized beam produced at the LISE fragment separator. The large value establishes a very mixed wave function with about equal amounts of normal and neutron particle-hole excited configurations contributing to its ground state wave function. This illustrates the transitional nature of isotopes at the border of the island-of-inversion.

  5. Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization

    PubMed Central

    Barnes, Alexander B.; Mak-Jurkauskas, Melody L.; Matsuki, Yoh; Bajaj, Vikram S.; van der Wel, Patrick C. A.; DeRocher, Ronald; Bryant, Jeffrey; Sirigiri, Jagadishwar R.; Temkin, Richard J.; Lugtenburg, Johan; Herzfeld, Judith; Griffin, Robert G.

    2009-01-01

    We describe a cryogenic sample exchange system that dramatically improves the efficiency of magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments by reducing the time required to change samples and by improving long-term instrument stability. Changing samples in conventional cryogenic MAS DNP/NMR experiments involves warming the probe to room temperature, detaching all cryogenic, RF, and microwave connections, removing the probe from the magnet, replacing the sample, and reversing all the previous steps, with the entire cycle requiring a few hours. The sample exchange system described here — which relies on an eject pipe attached to the front of the MAS stator and a vacuum jacketed dewar with a bellowed hole — circumvents these procedures. To demonstrate the excellent sensitivity, resolution, and stability achieved with this quadruple resonance sample exchange probe, we have performed high precision distance measurements on the active site of the membrane protein bacteriorhodopsin. We also include a spectrum of the tripeptide N-f-MLF-OH at 100 K which shows 30 Hz linewidths. PMID:19356957

  6. Cryogenic sample exchange NMR probe for magic angle spinning dynamic nuclear polarization.

    PubMed

    Barnes, Alexander B; Mak-Jurkauskas, Melody L; Matsuki, Yoh; Bajaj, Vikram S; van der Wel, Patrick C A; Derocher, Ronald; Bryant, Jeffrey; Sirigiri, Jagadishwar R; Temkin, Richard J; Lugtenburg, Johan; Herzfeld, Judith; Griffin, Robert G

    2009-06-01

    We describe a cryogenic sample exchange system that dramatically improves the efficiency of magic angle spinning (MAS) dynamic nuclear polarization (DNP) experiments by reducing the time required to change samples and by improving long-term instrument stability. Changing samples in conventional cryogenic MAS DNP/NMR experiments involves warming the probe to room temperature, detaching all cryogenic, RF, and microwave connections, removing the probe from the magnet, replacing the sample, and reversing all the previous steps, with the entire cycle requiring a few hours. The sample exchange system described here-which relies on an eject pipe attached to the front of the MAS stator and a vacuum jacketed dewar with a bellowed hole-circumvents these procedures. To demonstrate the excellent sensitivity, resolution, and stability achieved with this quadruple resonance sample exchange probe, we have performed high precision distance measurements on the active site of the membrane protein bacteriorhodopsin. We also include a spectrum of the tripeptide N-f-MLF-OH at 100K which shows 30 Hz linewidths. PMID:19356957

  7. Breit interaction effects in relativistic theory of the nuclear spin-rotation tensor

    NASA Astrophysics Data System (ADS)

    Aucar, I. Agustín; Gómez, Sergio S.; Giribet, Claudia G.; Ruiz de Azúa, Martín C.

    2013-09-01

    In this work, relativistic effects on the nuclear spin-rotation (SR) tensor originated in the electron-nucleus and electron-electron Breit interactions are analysed. To this end, four-component numerical calculations were carried out in model systems HX (X=H,F,Cl,Br,I). The electron-nucleus Breit interaction couples the electrons and nuclei dynamics giving rise to a purely relativistic contribution to the SR tensor. Its leading order in 1/c is of the same value as that of relativistic corrections on the usual second order expression of the SR tensor considered in previous work [I. A. Aucar, S. S. Gómez, J. I. Melo, C. G. Giribet, and M. C. Ruiz de Azúa, J. Chem. Phys. 138, 134107 (2013)], 10.1063/1.4796461, and therefore it is absolutely necessary to establish its relative importance. For the sake of completeness, the corresponding effect originating in the electron-electron Breit interaction is also considered. It is verified that in all cases these Breit interactions yield only very small corrections to the SR tensors of both the X and H nuclei in the present series of compounds. Results of the present work strongly suggest that in order to achieve experimental accuracy in the theoretical study of the SR tensor both electron-nucleus and electron-electron Breit effects can be safely neglected.

  8. Modeling the Influence of Nuclear Spin in the Reaction of H_3^+ with H_2

    NASA Astrophysics Data System (ADS)

    Crabtree, Kyle N.; Tom, Brian A.; McCall, Benjamin J.

    2011-06-01

    The reaction H_3^+ + H_2 ? H_2 + H_3^+ is among the simplest of bimolecular chemical reactions, and may play an important role in determining the ortho:para ratios of H_3^+ and H_2 in interstellar environments. Despite its apparent simplicity, the kinetics of this reaction is not well understood, particularly the branching fractions of the proton hop and hydrogen exchange reaction pathways. In this contribution, we present a series of steady state chemical models that show how this reaction can be studied in the laboratory with spectroscopy. Our first model is based entirely on nuclear spin statistics, appropriate for high temperature, low pressure plasmas. This model is then extended to account for the possibility of a small number of three-body collisions which could influence the interpretation of spectroscopic measurements of the H_3^+ + H_2 binary reaction. Our final model employs rate coefficients calculated using a microcanonical statistical approach which takes into account energetic restrictions on certain reaction pathways, which may become important at lower temperatures. These models are directly aimed at extracting kinetic information about the H_3^+ + H_2 reaction from laboratory spectra of hydrogenic plasmas.

  9. Nuclear spin dependence of the reaction of H3+ with H2. II. Experimental measurements

    NASA Astrophysics Data System (ADS)

    Crabtree, Kyle N.; Kauffman, Carrie A.; Tom, Brian A.; Beçka, Eftalda; McGuire, Brett A.; McCall, Benjamin J.

    2011-05-01

    The nuclear spin dependence of the chemical reaction H_3^+ + H2 ? H2 + H_3^+ has been studied in a hollow cathode plasma cell. Multipass infrared direct absorption spectroscopy has been employed to monitor the populations of several low-energy rotational levels of ortho- and para-H_3^+ (o-H_3^+ and p-H_3^+) in hydrogenic plasmas of varying para-H2 (p-H2) enrichment. The ratio of the rates of the proton hop (kH) and hydrogen exchange (kE) reactions ? ? kH/kE is inferred from the observed p-H_3^+ fraction as a function of p-H2 fraction using steady-state chemical models. Measurements have been performed both in uncooled (Tkin ˜ 350 K) and in liquid-nitrogen-cooled (Tkin ˜ 135 K) plasmas, marking the first time this reaction has been studied at low temperature. The value of ? has been found to decrease from 1.6 ± 0.1 at 350 K to 0.5 ± 0.1 at 135 K.

  10. -Supplementary Material -Electrical read-out of individual nuclear spin trajectories in a single-molecule magnet

    E-print Network

    . Terbium Double-Decker 1 S3. Nuclear Spin Read-Out 2 S4. Quantum Tunnelling of Magnetization 3 S5. Quantum magnetic field sweeps in three dimensions at field sweep rates up to 0.2 T/s. S2. TERBIUM DOUBLE-DECKER We used a Terbium (III) bis-phthalocyanine single molecule magnet (SMM), which is a metal-organic com

  11. Coherence time of the nuclear spin of ionized phosphorus donors in ^28Si at liquid He and room temperature

    NASA Astrophysics Data System (ADS)

    Thewalt, Michael L. W.; Saeedi, Kamyar; Simmons, Stephanie; Morton, John J. L.

    2013-03-01

    Remarkable coherence times have recently been reported for the nuclear spin of dilute neutral ^31P in highly enriched ^28Si [1]. For ionized ^31P, the removal of the hyperfine-coupled electron should result in a nuclear spin even more decoupled from the environment, and hence even longer coherence times at cryogenic temperatures. The coherence time of ionized ^31P was recently observed in natural Si, and while the nuclear coherence time was indeed much longer than the electron coherence time measured in the same device, it was limited to 18 ms due to both the presence of ^29Si as well as the readout mechanism being employed [2]. Here we report on coherence time measurements for ionized ^31P in the same ^28Si samples used for the previous [1] neutral donor study. In addition to the promise of longer cryogenic coherence times, the removal of the hyperfine-coupled electron should result in a profound change in the temperature dependence of T2. For the neutral donor, the electron T1 decreases very rapidly with increasing temperature, and even at 4.2 K the nuclear T2 is limited by the electron T1 [1]. This mechanism is absent for the ionized donor, and we will report on nuclear coherence time measurements for ionized ^31P at room temperature.[4pt] [1] M. Steger et al., Science 336, 1280 (2012).[0pt] [2] L. Dreher et al., Phys. Rev. Lett. 108, 027602 (2012).

  12. Population and decay of high-spin states in /sup 157-161/Yb: evolution of nuclear shapes as a function spin and neutron number

    SciTech Connect

    Jaeaeskelaeinen, M.; Sarantites, D.G.; Dilmanian, F.A.; Woodward, R.; Puchta, H.; Beene, J.R.; Halbert, M.L.; Hattula, J.; Hensley, D.C.; Barker, J.H.

    1982-01-01

    The population and decay of the entry states in /sup 157-161/Yb and /sup 155-158/Er from the reactions of 136- and 149-MeV /sup 20/Ne with /sup 144/Nd and /sup 146/Nd have been investigated with the Spin Spectrometer gated with a Ge detector. Statistical-model calculations reproduce the main features of the entry state populations. The entry lines, as a function of multiplicity, M/sub ..gamma../ show changes in slope at high M/sub ..gamma../ which are due to changes in the decay mode as a result of changes in nuclear structure. Energy spectra of the continuum ..gamma..-rays and angular distributions as a function of M/sub ..gamma../ show the onset of a dipole component localized at 650 +- 100 keV accompanied by an equally intense quadrupole component at twice the energy that continues to evolve to higher energies with increasing multiplicity. For /sup 157/ /sup 158/ /sup 159/ /sup 160/ /sup 161/Yb the dipole component appears at M/sub ..gamma../ = 21,22,23,25, and 27 (at spin I approx. = 38,40,42,45, and 50), respectively. At precisely these multiplicities the entry lines show a decrease in slope. In /sup 158/Yb the dipole component disappears at M/sub ..gamma../ = 28 and the entry line resumes its original slope. The results are consistent with the following picture. At low spins for /sup 157/ /sup 158/Yb the nuclear shapes evolve from prolate to slightly oblate particle-aligned structures. At I approx. = 38,40,42,45, and 50 the /sup 157/ /sup 158/ /sup 159/ /sup 160/ /sup 161/Yb nuclei, respectively, develop high-K rotational bands which may be built on oblate structures with large deformation (epsilon approx. = 0.3). At I = 49 a transition to triaxial shape appears to occur in /sup 158/Yb.

  13. Population and decay of high-spin states in /sup 157/-/sup 161/Yb: evolution of nuclear shapes as a function of spin and neutron number

    SciTech Connect

    Jaeaeskelaeinen, M.; Sarantites, D.G.; Dilmanian, F.A.; Woodward, R.; Puchta, H.; Beene, J.R.; Halbert, M.L.; Hattula, J.; Hensley, D.C.; Barker, J.H.

    1981-01-01

    The population and decay of the entry states in /sup 157/-/sup 161/Yb and /sup 155/-/sup 158/Er from the reactions of 136- and 149-MeV /sup 20/Ne with /sup 144/Nd and /sup 146/Nd have been investigated with the Spin Spectrometer gated with a Ge detector. Statistical-model calculations reproduce the main features of the entry state populations. The entry lines, as a function of multiplicity, M/sub ..gamma../, show changes in slope at high M/sub ..gamma../ which are due to changes in the decay mode as a result of changes in nuclear structure. Energy spectra of the continuum ..gamma..-rays and angular distributions as a function of M/sub ..gamma../ show the onset of a dipole component localized at 650 +- 100 keV accompanied by an equally intense quadrupole component at twice the energy that continues to evolve to higher energies with increasing multiplicity. For /sup 157/,/sup 158/,/sup 159/,/sup 160/,/sup 161/Yb the dipole component appears at M/sub ..gamma../ = 21, 22, 23, 25, and 27 (at spin I approx. = 38, 40, 42, 45, and 50), respectively. At precisely these multiplicities the entry lines show a decrease in slope. In /sup 158/Yb the dipole component disappears at M/sub ..gamma../ = 28 and the entry line resumes its original slope. The results are consistent with the following picture. At low spins for /sup 157/,/sup 158/Yb the nuclear shapes evolve from prolate to slightly oblate particle-aligned structures. At I approx. = 38, 40, 42, 45, and 50 the /sup 157/,/sup 158/,/sup 159/,/sup 160/,/sup 161/Yb nuclei, respectively, develop high-K rotational bands which may be built on oblate structures with large deformation (element of approx. = 0.3). At I = 49 a transition to triaxial shape appears to occur in /sup 158/Yb. 22 references.

  14. Large-scale nuclear structure calculations for spin-dependent WIMP scattering with chiral effective field theory currents

    E-print Network

    P. Klos; J. Menéndez; D. Gazit; A. Schwenk

    2015-01-23

    We perform state-of-the-art large-scale shell-model calculations of the structure factors for elastic spin-dependent WIMP scattering off 129,131Xe, 127I, 73Ge, 19F, 23Na, 27Al, and 29Si. This comprehensive survey covers the non-zero-spin nuclei relevant to direct dark matter detection. We include a pedagogical presentation of the formalism necessary to describe elastic and inelastic WIMP-nucleus scattering. The valence spaces and nuclear interactions employed have been previously used in nuclear structure calculations for these mass regions and yield a good spectroscopic description of these isotopes. We use spin-dependent WIMP-nucleus currents based on chiral effective field theory (EFT) at the one-body level and including the leading long-range two-body currents due to pion exchange, which are predicted in chiral EFT. Results for all structure factors are provided with theoretical error bands due to the nuclear uncertainties of WIMP currents in nuclei.

  15. Quantum state tomography of large nuclear spins in a semiconductor quantum well: Robustness against errors as quantified by condition numbers

    E-print Network

    Adam Miranowicz; Sahin K. Ozdemir; Jiri Bajer; Go Yusa; Nobuyuki Imoto; Yoshiro Hirayama; Franco Nori

    2014-10-09

    We discuss methods of quantum state tomography for solid-state systems with a large nuclear spin $I=3/2$ in nanometer-scale semiconductors devices based on a quantum well. Due to quadrupolar interactions, the Zeeman levels of these nuclear-spin devices become nonequidistant, forming a controllable four-level quantum system (known as quartit or ququart). The occupation of these levels can be selectively and coherently manipulated by multiphoton transitions using the techniques of nuclear magnetic resonance (NMR) [Yusa et al., Nature (London) 434, 101 (2005)]. These methods are based on an unconventional approach to NMR, where the longitudinal magnetization $M_z$ is directly measured. This is in contrast to the standard NMR experiments and tomographic methods, where the transverse magnetization $M_{xy}$ is detected. The robustness against errors in the measured data is analyzed by using condition numbers. We propose several methods with optimized sets of rotations. The optimization is applied to decrease the number of NMR readouts and to improve the robustness against errors, as quantified by condition numbers. An example of state reconstruction, using Monte Carlo methods, is presented. Tomographic methods for quadrupolar nuclei with higher-spin numbers (including $I=7/2$) are also described.

  16. Flexible nuclear screening approximation to the two-electron spin–orbit coupling based on ab initio parameterization

    SciTech Connect

    Chalupský, Jakub, E-mail: jakub@ims.ac.jp; Yanai, Takeshi [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan)] [Department of Theoretical and Computational Molecular Science, Institute for Molecular Science, Okazaki, Aichi 444-8585 (Japan)

    2013-11-28

    The derivation, implementation, and validation of a new approximation to the two-electron spin–orbit coupling (SOC) terms is reported. The approximation, referred to as flexible nuclear screening spin–orbit, is based on the effective one-electron spin–orbit operator and accounts for two-electron SOC effects by screening nuclear charges. A highly flexible scheme for the nuclear screening is developed, mainly using parameterization based on ab initio atomic SOC calculations. Tabulated screening parameters are provided for contracted and primitive Gaussian-type basis functions of the ANO-RCC basis set for elements from H to Cm. The strategy for their adaptation to any other Gaussian basis set is presented and validated. A model to correct for the effect of splitting of transition metal d orbitals on their SOC matrix elements is introduced. The method is applied to a representative set of molecules, and compared to exact treatment and other approximative approaches at the same level of relativistic theory. The calculated SOC matrix elements are in very good agreement with their “exact” values; deviation below 1% is observed on average. The presented approximation is considered to be generally applicable, simple to implement, highly efficient, and accurate.

  17. Flexible nuclear screening approximation to the two-electron spin-orbit coupling based on ab initio parameterization

    NASA Astrophysics Data System (ADS)

    Chalupský, Jakub; Yanai, Takeshi

    2013-11-01

    The derivation, implementation, and validation of a new approximation to the two-electron spin-orbit coupling (SOC) terms is reported. The approximation, referred to as flexible nuclear screening spin-orbit, is based on the effective one-electron spin-orbit operator and accounts for two-electron SOC effects by screening nuclear charges. A highly flexible scheme for the nuclear screening is developed, mainly using parameterization based on ab initio atomic SOC calculations. Tabulated screening parameters are provided for contracted and primitive Gaussian-type basis functions of the ANO-RCC basis set for elements from H to Cm. The strategy for their adaptation to any other Gaussian basis set is presented and validated. A model to correct for the effect of splitting of transition metal d orbitals on their SOC matrix elements is introduced. The method is applied to a representative set of molecules, and compared to exact treatment and other approximative approaches at the same level of relativistic theory. The calculated SOC matrix elements are in very good agreement with their "exact" values; deviation below 1% is observed on average. The presented approximation is considered to be generally applicable, simple to implement, highly efficient, and accurate.

  18. Nuclear Spin Symmetry Conservation and Relaxation in Water (1H216O) Studied by Cavity Ring-Down (CRD) Spectroscopy of Supersonic Jets

    NASA Astrophysics Data System (ADS)

    Manca Tanner, Carine; Quack, Martin; Schmidiger, David

    2013-10-01

    We report high resolution near-infrared laser spectra of water seeded in a supersonic jet expansion of argon probed by cavity ring-down spectroscopy (CRDS) in the R branch of the 2-3 band (above 7500 cm-1) at several effective temperatures T < 30 K. Our goal is to study nuclear spin symmetry conservation and relaxation. For low mole fractions of water in the gas mixture, we obtained the lowest rotational temperatures and observed nuclear spin symmetry conservation, in agreement with theoretical expectation for inelastic collisions of isolated H2O molecules with Ar and similar to a previous series of experiments with other small molecules in supersonic jet expansions. However, for the highest mole fractions of water, which we used (xH2O < 1.6%), we obtained slightly higher rotational temperatures and observed nuclear spin symmetry relaxation, which cannot be explained by the intramolecular quantum relaxation mechanism in the monomer H2O. The nuclear spin symmetry relaxation observed is, indeed, seen to be related to the formation of water clusters at the early stage of the supersonic jet expansion. Under these conditions, two mechanisms can contribute to nuclear spin symmetry relaxation. The results are discussed in relation to claims of the stability of nuclear spin isomers of H2O in the condensed phase and briefly also to astrophysical spectroscopy.

  19. Theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis-, and trans-1,2-difluoroethylenes

    NASA Astrophysics Data System (ADS)

    Nozirov, Farhod; Kupka, Teobald; Stachów, Micha?

    2014-04-01

    A theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis- and trans-1,2-difluoroethylenes is reported. The results obtained using density functional theory (DFT) combined with large basis sets and gauge-independent atomic orbital calculations were critically compared with experiment and conventional, higher level correlated electronic structure methods. Accurate structural, vibrational, and NMR parameters of difluoroethylenes were obtained using several density functionals combined with dedicated basis sets. B3LYP/6-311++G(3df,2pd) optimized structures of difluoroethylenes closely reproduced experimental geometries and earlier reported benchmark coupled cluster results, while BLYP/6-311++G(3df,2pd) produced accurate harmonic vibrational frequencies. The most accurate vibrations were obtained using B3LYP/6-311++G(3df,2pd) with correction for anharmonicity. Becke half and half (BHandH) density functional predicted more accurate 19F isotropic shieldings and van Voorhis and Scuseria's ?-dependent gradient-corrected correlation functional yielded better carbon shieldings than B3LYP. A surprisingly good performance of Hartree-Fock (HF) method in predicting nuclear shieldings in these molecules was observed. Inclusion of zero-point vibrational correction markedly improved agreement with experiment for nuclear shieldings calculated by HF, MP2, CCSD, and CCSD(T) methods but worsened the DFT results. The threefold improvement in accuracy when predicting 2J(FF) in 1,1-difluoroethylene for BHandH density functional compared to B3LYP was observed (the deviations from experiment were -46 vs. -115 Hz).

  20. Theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis-, and trans-1,2-difluoroethylenes

    SciTech Connect

    Nozirov, Farhod, E-mail: teobaldk@gmail.com, E-mail: farhod.nozirov@gmail.com [Department of Physics, 4513 Manhattan College Parkway Riverdale, New York 10471 (United States)] [Department of Physics, 4513 Manhattan College Parkway Riverdale, New York 10471 (United States); Stachów, Micha?, E-mail: michal.stachow@gmail.com [Faculty of Chemistry, Opole University, 48, Oleska Street, 45-052 Opole (Poland)] [Faculty of Chemistry, Opole University, 48, Oleska Street, 45-052 Opole (Poland); Kupka, Teobald, E-mail: teobaldk@gmail.com, E-mail: farhod.nozirov@gmail.com

    2014-04-14

    A theoretical prediction of nuclear magnetic shieldings and indirect spin-spin coupling constants in 1,1-, cis- and trans-1,2-difluoroethylenes is reported. The results obtained using density functional theory (DFT) combined with large basis sets and gauge-independent atomic orbital calculations were critically compared with experiment and conventional, higher level correlated electronic structure methods. Accurate structural, vibrational, and NMR parameters of difluoroethylenes were obtained using several density functionals combined with dedicated basis sets. B3LYP/6-311++G(3df,2pd) optimized structures of difluoroethylenes closely reproduced experimental geometries and earlier reported benchmark coupled cluster results, while BLYP/6-311++G(3df,2pd) produced accurate harmonic vibrational frequencies. The most accurate vibrations were obtained using B3LYP/6-311++G(3df,2pd) with correction for anharmonicity. Becke half and half (BHandH) density functional predicted more accurate {sup 19}F isotropic shieldings and van Voorhis and Scuseria's ?-dependent gradient-corrected correlation functional yielded better carbon shieldings than B3LYP. A surprisingly good performance of Hartree-Fock (HF) method in predicting nuclear shieldings in these molecules was observed. Inclusion of zero-point vibrational correction markedly improved agreement with experiment for nuclear shieldings calculated by HF, MP2, CCSD, and CCSD(T) methods but worsened the DFT results. The threefold improvement in accuracy when predicting {sup 2}J(FF) in 1,1-difluoroethylene for BHandH density functional compared to B3LYP was observed (the deviations from experiment were ?46 vs. ?115 Hz)

  1. Spin transition in iron(II) complexes induced by heat, pressure, light, and nuclear decay

    Microsoft Academic Search

    P. Gütlich

    1987-01-01

    The phenomenon of temperature-dependent spin transition will be introduced and the numerous chemical and physical influences\\u000a affecting the spin transition characteristics will be discussed. We shall mainly concentrate on the spin crossover system\\u000a [Fe(2-pic)3]X2Sol (2-pic=2-aminomethylpyridine; X=Cl, Br; Sol=C2H5OH, CH3OH) and demonstrate how the behaviour of the spin transition5T2g(Oh)?1A1g(Oh) is influenced by substituting the metalion, the non-coordinating anions X, the crystal

  2. Matrix Isolation Spectroscopy and Nuclear Spin Conversion of NH3 and ND3 in Solid Parahydrogen

    NASA Astrophysics Data System (ADS)

    Ruzi, Mahmut; Anderson, David T.

    2013-10-01

    We present matrix isolation infrared absorption spectra of NH3 and ND3 trapped in solid parahydrogen (pH2) at temperatures around 1.8 K. We used the relatively slow nuclear spin conversion (NSC) of NH3 and ND3 in freshly deposited pH2 samples as a tool to assign the sparse vibration-inversion-rotation (VIR) spectra of NH3 in the regions of the -2, -4, 2-4, -1, and -3 bands and ND3 in the regions of the -2, -4, -1, and -3 fundamentals. Partial assignments are also presented for various combination bands of NH3. Detailed analysis of the -2 bands of NH3 and ND3 indicates that both isotopomers are nearly free rotors; that the vibrational energy is blue-shifted by 1-2%; and that the rotational constants and inversion tunneling splitting are 91-94% and 67-75%, respectively, of the gas-phase values. The line shapes of the VIR absorptions are narrow (0.2-0.4 cm-1) for upper states that cannot rotationally relax and broad (>1 cm-1) for upper states that can rotationally relax. We report and assign a number of NH3-induced infrared absorption features of the pH2 host near 4150 cm-1, along with a cooperative transition that involves simultaneous vibrational excitation of a pH2 molecule and rotation-inversion excitation of NH3. The NSCs of NH3 and ND3 were found to follow first-order kinetics with rate constants at 1.8 K of k = 1.88(16) - 10-3 s-1 and k = 1.08(8) - 10-3 s-1, respectively. These measured rate constants are compared to previous measurements for NH3 in an Ar matrix and with the rate constants measured for other dopant molecules isolated in solid pH2.

  3. Matrix isolation spectroscopy and nuclear spin conversion of NH3 and ND3 in solid parahydrogen.

    PubMed

    Ruzi, Mahmut; Anderson, David T

    2013-10-01

    We present matrix isolation infrared absorption spectra of NH3 and ND3 trapped in solid parahydrogen (pH2) at temperatures around 1.8 K. We used the relatively slow nuclear spin conversion (NSC) of NH3 and ND3 in freshly deposited pH2 samples as a tool to assign the sparse vibration-inversion-rotation (VIR) spectra of NH3 in the regions of the ?2, ?4, 2?4, ?1, and ?3 bands and ND3 in the regions of the ?2, ?4, ?1, and ?3 fundamentals. Partial assignments are also presented for various combination bands of NH3. Detailed analysis of the ?2 bands of NH3 and ND3 indicates that both isotopomers are nearly free rotors; that the vibrational energy is blue-shifted by 1-2%; and that the rotational constants and inversion tunneling splitting are 91-94% and 67-75%, respectively, of the gas-phase values. The line shapes of the VIR absorptions are narrow (0.2-0.4 cm(-1)) for upper states that cannot rotationally relax and broad (>1 cm(-1)) for upper states that can rotationally relax. We report and assign a number of NH3-induced infrared absorption features of the pH2 host near 4150 cm(-1), along with a cooperative transition that involves simultaneous vibrational excitation of a pH2 molecule and rotation-inversion excitation of NH3. The NSCs of NH3 and ND3 were found to follow first-order kinetics with rate constants at 1.8 K of k = 1.88(16) × 10(-3) s(-1) and k = 1.08(8) × 10(-3) s(-1), respectively. These measured rate constants are compared to previous measurements for NH3 in an Ar matrix and with the rate constants measured for other dopant molecules isolated in solid pH2. PMID:23594210

  4. Water, hydrogen, deuterium, carbon, carbon-13, and oxygen-18 content of selected lunar material

    USGS Publications Warehouse

    Friedman, I.; O'Neil, J.R.; Adami, L.H.; Gleason, J.D.; Hardcastle, K.

    1970-01-01

    The water content of the breccia is 150 to 455 ppm, with a ??D from -580 to -870 per mil. Hydrogen gas content is 40 to 53 ppm with a ??D of -830 to -970 per mil. The CO2 is 290 to 418 ppm with S 13C = + 2.3 to + 5.1 per mil and ??18O = 14.2 to 19.1 per mil. Non-CO2 carbon is 22 to 100 ppm, ??18C = -6.4 to -23.2 per mil. Lunar dust is 810 ppm H2O (D = 80 ppm) and 188 ppm total carbon (??13C = -17.6 per mil). The 18O analyses of whole rocks range from 5.8 to 6.2 per mil. The temperature of crystallization of type B rocks is 1100?? to 1300??C, based on the oxygen isotope fractionation between coexisting plagioclase and ilmenite.

  5. Nuclear spin-dependent interactions: searches for WIMP, axion and topological defect dark matter, and tests of fundamental symmetries

    NASA Astrophysics Data System (ADS)

    Stadnik, Y. V.; Flambaum, V. V.

    2015-03-01

    We calculate the proton and neutron spin contributions for nuclei using semi-empirical methods, as well as a novel hybrid ab initio/semi-empirical method, for interpretation of experimental data. We demonstrate that core-polarisation corrections to ab initio nuclear shell model calculations generally reduce discrepancies in proton and neutron spin expectation values from different calculations. We derive constraints on the spin-dependent P,T-violating interaction of a bound proton with nucleons, which for certain ranges of exchanged pseudoscalar boson masses improve on the most stringent laboratory limits by several orders of magnitude. We derive a limit on the CPT and Lorentz-invariance-violating parameter GeV, which improves on the most stringent existing limit by a factor of 8, and we demonstrate sensitivities to the parameters and at the level - GeV, which is a one order of magnitude improvement compared to the corresponding existing sensitivities. We extend previous analysis of nuclear anapole moment data for Cs to obtain new limits on several other CPT and Lorentz-invariance-violating parameters: GeV, , GeV and.

  6. Theory of long-lived nuclear spin states in methyl groups and quantum-rotor induced polarisation

    NASA Astrophysics Data System (ADS)

    Dumez, Jean-Nicolas; Hâkansson, Pär; Mamone, Salvatore; Meier, Benno; Stevanato, Gabriele; Hill-Cousins, Joseph T.; Roy, Soumya Singha; Brown, Richard C. D.; Pileio, Giuseppe; Levitt, Malcolm H.

    2015-01-01

    Long-lived nuclear spin states have a relaxation time much longer than the longitudinal relaxation time T1. Long-lived states extend significantly the time scales that may be probed with magnetic resonance, with possible applications to transport and binding studies, and to hyperpolarised imaging. Rapidly rotating methyl groups in solution may support a long-lived state, consisting of a population imbalance between states of different spin exchange symmetries. Here, we expand the formalism for describing the behaviour of long-lived nuclear spin states in methyl groups, with special attention to the hyperpolarisation effects observed in 13CH3 groups upon rapidly converting a material with low-barrier methyl rotation from the cryogenic solid state to a room-temperature solution [M. Icker and S. Berger, J. Magn. Reson. 219, 1 (2012)]. We analyse the relaxation properties of methyl long-lived states using semi-classical relaxation theory. Numerical simulations are supplemented with a spherical-tensor analysis, which captures the essential properties of methyl long-lived states.

  7. Cosmogonic Indicators in the Jupiter-family Comet 103P/Hartley-2: Deuterium Abundance and Nuclear Spin Temperature

    NASA Astrophysics Data System (ADS)

    Bonev, Boncho P.; Gibb, Erika L.; Disanti, Michael A.; Villanueva, Geronimo L.; Mumma, Michael J.; Kuan, Yi-Jehng; Charnley, Steven B.; Magee-Sauer, Karen; Combi, Michael R.

    2010-08-01

    Using NIRSPEC at Keck-2, we propose sensitive high-resolution observations of the coma of comet 103P/Hartley-2. We will (1) search for HDO and CH_3D, (2) measure the nuclear spin temperature of formaldehyde, and (3) perform spatially resolved measurements of the spin and rotational temperature of water in the coma. These investigations are coordinated with radio observations targeting DCN and HDCO. The proposed program addresses problems of interdisciplinary interest with cosmogonic and astrobiological implications, including the origin of cometary organics and the (widely disputed) question of the deuterium enrichment of cometary water compared with Earth's oceans. The proposed measurements are far from routine: HDO and CH_3D are still to be securely detected in the infrared, while the spin temperature of cometary formaldehyde has not been measured. The close (~0.1 AU from Earth) bright apparition of Hartley-2, coupled with the cross-dispersed capabilities of NIRSPEC, provides a very rare opportunity to conduct deep searches and study these cosmogonic parameters (D/H and spin temperature) in unprecedented detail. The NSF Astronomy and Astrophysics Research Grants program is supporting the proposed studies through award AST-0807939.

  8. Unraveling multi-spin effects in rotational resonance nuclear magnetic resonance using effective reduced density matrix theory

    SciTech Connect

    SivaRanjan, Uppala; Ramachandran, Ramesh, E-mail: rramesh@iisermohali.ac.in [Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Manauli, P.O. Box-140306, Mohali, Punjab (India)] [Department of Chemical Sciences, Indian Institute of Science Education and Research (IISER) Mohali, Sector 81, Manauli, P.O. Box-140306, Mohali, Punjab (India)

    2014-02-07

    A quantum-mechanical model integrating the concepts of reduced density matrix and effective Hamiltonians is proposed to explain the multi-spin effects observed in rotational resonance (R{sup 2}) nuclear magnetic resonance (NMR) experiments. Employing this approach, the spin system of interest is described in a reduced subspace inclusive of its coupling to the surroundings. Through suitable model systems, the utility of our theory is demonstrated and verified with simulations emerging from both analytic and numerical methods. The analytic results presented in this article provide an accurate description/interpretation of R{sup 2} experimental results and could serve as a test-bed for distinguishing coherent/incoherent effects in solid-state NMR.

  9. Carbon13 and Carbon14 Abundances in Alaskan Aquatic Organisms: Delayed Production from Peat in Arctic Food Webs

    Microsoft Academic Search

    Donald M. Schell

    1983-01-01

    Inputs of terrestrial peat carbon to the nearshore Alaskan Beaufort Sea from erosion and fluvial transport are of the same magnitude as in situ primary production within 10 kilometers of shore. Nevertheless, carbon-13\\/carbon-12 ratios and carbon-14 abundances in marine organisms show that only small amounts of the terrestrial carbon are transferred beyond the microbial level. Freshwater organisms, however, are heavily

  10. Effect of delta ferrite on impact properties of low carbon 13Cr–4Ni martensitic stainless steel

    Microsoft Academic Search

    P. Wang; S. P. Lu; N. M. Xiao; D. Z. Li; Y. Y. Li

    2010-01-01

    The effect of delta ferrite on impact properties of low carbon 13Cr–4Ni martensitic stainless steel was studied by instrumented Charpy impact, SEM fractographic analysis and EDS. The experimental results indicated the presence of delta ferrite did not change the upper and lower shelf energy of the steel apparently, while lowered the impact energy remarkably in the transition temperature range and

  11. Relativistic nuclear corrections to the spin structure function of the deuteron in the light-cone variables

    SciTech Connect

    Pavlov, F. F., E-mail: f.pavlov@tuexph.stu.neva.ru [St. Petersburg State Polytechnic University (Russian Federation)

    2012-06-15

    The relativistic deuteron has been considered in the light-cone formalism as a system of two strongly interacting nucleons (two-nucleon approximation). The technique for the calculation of the average helicity of the proton in the deuteron has been considered in the light-cone variables. A receipt has been pro-posed for the consistent calculation of relativistic nuclear corrections to the average helicity of the proton in the deuteron and to the spin structure function of the deuteron g{sub 1}{sup D}. Relativistic-correction-induced change in the Bjorken sum rule has been discussed.

  12. Nuclear Magnetic Resonance Spectroscopy Applications: Proton NMR In Biological Objects Subjected To Magic Angle Spinning

    SciTech Connect

    Wind, Robert A.; Hu, Jian Zhi

    2005-01-01

    Proton NMR in Biological Objects Submitted to Magic Angle Spinning, In Encyclopedia of Analytical Science, Second Edition (Paul J. Worsfold, Alan Townshend and Colin F. Poole, eds.), Elsevier, Oxford 6:333-342. Published January 1, 2005. Proposal Number 10896.

  13. ? nuclear magnetic resonance and electron spin resonance of amorphous hydrogenated carbon

    NASA Astrophysics Data System (ADS)

    Blinc, R.; Arcon, D.; Cevc, P.; Pocsik, I.; Koos, M.; Trontelj, Z.; Jaglicic, Z.

    1998-08-01

    The temperature dependences of the 0953-8984/10/30/019/img9 and 0953-8984/10/30/019/img10 magnetization recovery and spin-lattice relaxation times as well as the 0953-8984/10/30/019/img9 NMR spectra have been studied between 300 K and 4 K. The observed short and nearly temperature independent proton and 0953-8984/10/30/019/img9 spin-lattice relaxation times demonstrate that the dominant spin-lattice relaxation mechanism is spin diffusion to paramagnetic impurities. The fact that the magnetization recovery curves clearly deviate from the single-exponential form expected for the case of spin diffusion and randomly distributed paramagnetic centres demonstrates that the paramagnetic centres aggregate in clusters. Superparamagnetic freezing effects expected for such an inhomogeneous distribution are indeed seen below 50 K in the temperature dependence of the electron spin-resonance (ESR) intensity, the 0953-8984/10/30/019/img9 NMR spectra and the SQUID magnetization measurements which show a distinct magnetic hysteresis loop.

  14. Rotational spectrum and carbon-13 hyperfine structure of the C3H, C5H, C6H, and C7H radicals

    NASA Astrophysics Data System (ADS)

    McCarthy, M. C.; Thaddeus, P.

    2005-05-01

    By means of Fourier transform microwave spectroscopy of a supersonic molecular beam, we have detected the singly substituted carbon-13 isotopic species of C5H, C6H, and C7H. Hyperfine structure in the rotational transitions of the lowest-energy fine structure component (?1/22 for C5H and C7H, and ?3/22 for C6H) of each species was measured between 6 and 22GHz, and precise rotational, centrifugal distortion, ?-doubling, and C13 hyperfine coupling constants were determined. In addition, resolved hyperfine structure in the lowest rotational transition (J=3/2?1/2) of the three C13 isotopic species of C3H was measured by the same technique. By combining the centimeter-wave measurements here with previous millimeter-wave data, a complete set of C13 hyperfine coupling constants were derived to high precision for each isotopic species. Experimental structures (r0) have been determined for C5H and the two longer carbon-chain radicals, and these are found to be in good agreement with the predictions of high-level coupled-cluster calculations. C3H, C5H, and C7H exhibit a clear alternation in the magnitude and sign of the C13 hyperfine coupling constants along the carbon-chain backbone. Because the electron spin density is nominally zero at the central carbon atom of C3H, C5H, and C7H, and at alternating sets of carbon atoms of C5H and C7H, owing to spin polarization, almost all of the C13 coupling constants at these atoms are small in magnitude and negative in sign. Spin-polarization effects are known to be important for the Fermi-contact (bF) term, but prior to the work here they have generally been neglected for the hyperfine terms a, c, and d.

  15. Utilization of site-directed spin labeling and high-resolution heteronuclear nuclear magnetic resonance for global fold determination of large proteins with limited nuclear overhauser effect data.

    PubMed

    Battiste, J L; Wagner, G

    2000-05-01

    To test whether distances derived from paramagnetic broadening of (15)N heteronuclear single quantum coherence (HSQC) resonances could be used to determine the global fold of a large, perdeuterated protein, we used site-directed spin-labeling of 5 amino acids on the surface of (15)N-labeled eukaryotic translation initiation factor 4E (eIF4E). eIF4E is a 25 kDa translation initiation protein, whose solution structure was previously solved in a 3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate hydrate (CHAPS) micelle of total molecular mass approximately 45-50 kDa. Distance-dependent line broadening consistent with the three-dimensional structure of eIF4E was observed for all spin-label substitutions. The paramagnetic broadening effects (PBEs) were converted into distances for modeling by a simple method comparing peak heights in (15)N-HSQC spectra before and after reduction of the nitroxide spin label with ascorbic acid. The PBEs, in combination with HN-HN nuclear Overhauser effects (NOEs) and chemical shift index (CSI) angle restraints, correctly determined the global fold of eIF4E with a backbone precision of 2.3 A (1.7 A for secondary structure elements). The global fold was not correctly determined with the HN-HN NOEs and CSI angles alone. The combination of PBEs with simulated restraints from another nuclear magnetic resonance (NMR) method for global fold determination of large proteins (methyl-protonated, highly deuterated samples) improved the quality of calculated structures. In addition, the combination of the two methods simulated from a crystal structure of an all alpha-helical protein (40 kDa farnesyl diphoshphate synthase) correctly determined the global fold where neither method individually was successful. These results show the potential feasibility of obtaining medium-resolution structures for proteins in the 40-100 kDa range via NMR. PMID:10820006

  16. The importance of nuclear spin diffusion as an angularly independent relaxation mechanism controlling the matrix ENDOR response of radicals in molecular crystals

    NASA Astrophysics Data System (ADS)

    Schlick, Shulamith; Kevan, Larry; Toriyama, K.; Iwasaki, M.

    1981-01-01

    In the generalized matrix ENDOR line shape model [P.A. Narayana et al., J. Chem. Phys., 67, 1990 (1977)] the ENDOR intensity is controlled by the nuclear spin lattice relaxation rate formulated as an angularly dependent electron-nuclear dipolar contribution and an angularly independent intrinsic bulk nuclear relaxation contribution. Comparison of this model with single crystal data [L. Kevan et al., J. Chem. Phys., 70, 5006 (1979)] showed that the angularly independent relaxation rate must be more rapid than the intrinsic bulk nuclear relaxation rate. Here we identify the angularly independent relaxation rate with nuclear spin diffusion and apply this interpretation quantitatively to data on methyl radicals in lithium acetate dihydrate crystals and to the radiation generated CH3CH(NH3)?OOH- radical in alanine at 77 K.

  17. Temperature-dependent dynamical nuclear polarization bistabilities in double quantum dots in the spin-blockade regime

    NASA Astrophysics Data System (ADS)

    Lunde, Anders Mathias; López-Monís, Carlos; Vasiliadou, Ioanna A.; Bonilla, Luis L.; Platero, Gloria

    2013-07-01

    The interplay of dynamical nuclear polarization (DNP) and leakage current through a double quantum dot in the spin-blockade regime is analyzed. A finite DNP is built up due to a competition between hyperfine (HF) spin-flip transitions and another inelastic escape mechanism from the triplets, which block transport. We focus on the temperature dependence of the DNP for zero energy detuning (i.e., equal electrostatic energy of one electron in each dot and a singlet in the right dot). Our main result is the existence of a transition temperature, below which the DNP is bistable, so a hysteretic leakage current versus external magnetic field B appears. This is studied in two cases: (i) close to the crossing of the three triplet energy levels near B=0, where spin-blockade is lifted due to the inhomogeneity of the effective magnetic field from the nuclei. (ii) At higher B-fields, where the two spin-polarized triplets simultaneously cross two different singlet energy levels. We develop simplified models leading to different transition temperatures Tc,TT and Tc,ST for the crossing of the triplet levels and the singlet-triplet level crossings, respectively. We find Tc,TT analytically to be given solely by the HF couplings, whereas Tc,ST depends on various parameters and Tc,ST>Tc,TT. The key idea behind the existence of the transition temperatures at zero energy detuning is the suppression of energy absorption compared to emission in the inelastic HF transitions. Finally, by comparing the rate equation results with Monte Carlo simulations, we discuss the importance of having both HF interaction and another escape mechanism from the triplets to induce a finite DNP.

  18. 63Cu nuclear magnetic resonance study of Pr1.85Ce0.15Cu1 - xNixO4: Ni-induced spin density oscillation and modification of the low energy spin fluctuations

    NASA Astrophysics Data System (ADS)

    Williams, G. V. M.; Jurkutat, M.; Rybicki, D.; Haase, J.

    2011-02-01

    We report the results from a 63Cu nuclear magnetic resonance (NMR) study of the electron-doped high temperature superconducting cuprate (HTSC) Pr1.85Ce0.15Cu1 - xNixO4. We find that Ni induces a magnetic broadening of the 63Cu NMR spectra that can be interpreted in terms of an induced spin density oscillation about the Ni site, similar to that reported from 63Cu NMR measurements on the hole-doped HTSCs when Zn is partially substituted for Cu. There is also an additional temperature-dependent contribution to the 63Cu spin-lattice relaxation rate that can be interpreted in terms of an Ni-induced modification of the low energy spin fluctuations. Furthermore, the spin fluctuations are intrinsically spatially inhomogeneous and additional inhomogeneities are induced by Ni.

  19. The Nuclear Responses for Double Beta Neutrinos and Double Spin Isospin Resonances by Using of Double Charge Exchange Heavey Ion Reaction

    NASA Astrophysics Data System (ADS)

    Takahisa, K.; Akimune, H.; Ejiri, H.; Fujimura, H.; Fujiwara, M.; Hara, K.; Hasimoto, H.; Hatanaka, K.; Itahasi, T.; Kawabata, T.; Kawase, K.; Koreeda, Y.; Maehara, N.; Mordechai, S.; Nagai, Y.; Nakanishi, K.; Ninomiya, S.; Shima, T.; Tanaka, M.; Umehara, S.; Umisedo, S.; Yoshida, H. P.; Yoshida, S.; Yoshimura, M.; Yosoi, M.

    2005-12-01

    To study double spin-isospin responses in view of the ??? decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher ?L excitations.

  20. On the origin of high- spin states in nuclear fission fragments

    E-print Network

    G. Mouze; C. Ythier; S. Hachem

    2011-03-28

    In the "nucleon-phase" model of binary fission, the transfer of nucleons between an A =126 {\\guillemotleft} nucleon core {\\guillemotright} and the primordial "cluster" can explain both the formation of high- spin states and the saw-tooth behavior of the variation, as a function of fragment mass, of the average angular momentum.

  1. Nuclear spin-orbit interaction and T-odd angular correlations in ternary fission

    E-print Network

    A. L. Barabanov

    2014-07-08

    T-odd angular correlations in ternary fission of 233-U and 235-U nuclei by slow polarized neutrons are not related to TRI (time reversal invariance) violation, but are caused by an effective spin-orbit interaction in the final state.

  2. Devices and process for high-pressure magic angle spinning nuclear magnetic resonance

    DOEpatents

    Hoyt, David W; Sears, Jr., Jesse A; Turcu, Romulus V.F.; Rosso, Kevin M; Hu, Jian Zhi

    2014-04-08

    A high-pressure magic angle spinning (MAS) rotor is detailed that includes a high-pressure sample cell that maintains high pressures exceeding 150 bar. The sample cell design minimizes pressure losses due to penetration over an extended period of time.

  3. Nuclear Configurations in the Spin-Orbit Coupling Model. I. Empirical Evidence

    Microsoft Academic Search

    Maria Goeppert Mayer

    1950-01-01

    An extreme one particle model of the nucleus is proposed. The model is based on the succession of energy levels of a single particle in a potential between that of a three-dimensional harmonic oscillator and a square well. (1) Strong spin orbit coupling leading to inverted doublets is assumed. (2) An even number of identical nucleons are assumed to couple

  4. Applications of carbon-13 and sodium-23 NMR in the study of plants, animal, and human cells

    SciTech Connect

    Sillerud, L.O.; Heyser, J.W.; Han, C.H.; Bitensky, M.W.

    1984-01-01

    Carbon-13 and sodium-23 NMR have been applied to the study of a variety of plant, animal and human cell types. Sodium NMR, in combination with dysprosium shift reagents, has been used to monitor sodium transport kinetics in salt-adapted, and non-adapted cells of P. milliaceum and whole D. spicata plants. The sodium content of human erythrocytes and leukemic macrophages was measured. Carbon-13 NMR was used to determine the structure and metabolism of rat epididymal fat pad adipocytes in real time. Insulin and isoproterenol-stimulated triacylglycerol turnover could be monitored in fat cell suspensions. (1-/sup 13/C) glucose was used as a substrate to demonstrate futile metabolic cycling from glucose to glycerol during lypolysis. Cell wall polysaccharide synthesis was followed in suspensions of P. milliaceum cells using (1-/sup 13/C) glucose as a precursor. These results illustrate the wide range of living systems which are amenable to study with NMR. 14 refs., 21 figs.

  5. Dynamic carbon 13 breath tests for the study of liver function and gastric emptying.

    PubMed

    Bonfrate, Leonilde; Grattagliano, Ignazio; Palasciano, Giuseppe; Portincasa, Piero

    2015-02-01

    In gastroenterological practice, breath tests (BTs) are diagnostic tools used for indirect, non-invasive assessment of several pathophysiological metabolic processes, by monitoring the appearance in breath of a metabolite of a specific substrate. Labelled substrates originally employed radioactive carbon 14 ((14)C) and, more recently, the stable carbon 13 isotope ((13)C) has been introduced to label specific substrates. The ingested (13)C-substrate is metabolized, and exhaled (13)CO2 is measured by mass spectrometry or infrared spectroscopy. Some (13)C-BTs evaluate specific (microsomal, cytosolic, and mitochondrial) hepatic metabolic pathways and can be employed in liver diseases (i.e. simple liver steatosis, non-alcoholic steato-hepatitis, liver fibrosis, cirrhosis, hepatocellular carcinoma, drug and alcohol effects). Another field of clinical application for (13)C-BTs is the assessment of gastric emptying kinetics in response to liquids ((13)C-acetate) or solids ((13)C-octanoic acid in egg yolk or in a pre-packed muffin or the (13)C-Spirulina platensis given with a meal or a biscuit). Studies have shown that (13)C-BTs, used for gastric emptying studies, yield results that are comparable to scintigraphy and can be useful in detecting either delayed- (gastroparesis) or accelerated gastric emptying or changes of gastric kinetics due to pharmacological effects. Thus, (13)C-BTs represent an indirect, cost-effective and easy method of evaluating dynamic liver function and gastric kinetics in health and disease, and several other potential applications are being studied. PMID:25339354

  6. Dynamic carbon 13 breath tests for the study of liver function and gastric emptying

    PubMed Central

    Bonfrate, Leonilde; Grattagliano, Ignazio; Palasciano, Giuseppe; Portincasa, Piero

    2015-01-01

    In gastroenterological practice, breath tests (BTs) are diagnostic tools used for indirect, non-invasive assessment of several pathophysiological metabolic processes, by monitoring the appearance in breath of a metabolite of a specific substrate. Labelled substrates originally employed radioactive carbon 14 (14C) and, more recently, the stable carbon 13 isotope (13C) has been introduced to label specific substrates. The ingested 13C-substrate is metabolized, and exhaled 13CO2 is measured by mass spectrometry or infrared spectroscopy. Some 13C-BTs evaluate specific (microsomal, cytosolic, and mitochondrial) hepatic metabolic pathways and can be employed in liver diseases (i.e. simple liver steatosis, non-alcoholic steato-hepatitis, liver fibrosis, cirrhosis, hepatocellular carcinoma, drug and alcohol effects). Another field of clinical application for 13C-BTs is the assessment of gastric emptying kinetics in response to liquids (13C-acetate) or solids (13C-octanoic acid in egg yolk or in a pre-packed muffin or the 13C-Spirulina platensis given with a meal or a biscuit). Studies have shown that 13C-BTs, used for gastric emptying studies, yield results that are comparable to scintigraphy and can be useful in detecting either delayed- (gastroparesis) or accelerated gastric emptying or changes of gastric kinetics due to pharmacological effects. Thus, 13C-BTs represent an indirect, cost-effective and easy method of evaluating dynamic liver function and gastric kinetics in health and disease, and several other potential applications are being studied. PMID:25339354

  7. Spin polarization of 29P produced through low energy nuclear reaction

    NASA Astrophysics Data System (ADS)

    Yaguchi, M.; Mihara, M.; Fukuda, M.; Nishimura, D.; Uenishi, H.; Iwamoto, K.; Wakabayashi, M.; Ohno, J.; Kamisho, Y.; Morita, Y.; Minamisono, T.; Matsuta, K.

    2013-05-01

    Spin polarization of short-lived ?-emitting nucleus 29P ( I ? = 1/2 + , T 1/2 = 4.14 s) produced through the 28P( d, n) 29P reaction was studied as functions of the incident deuteron energy E d and the recoil angle ? of 29P. New optimum condition was found at E d = 3.3 MeV and ? = 30° where polarization of 29P is -(4.1 ± 0.7) %.

  8. Research program in nuclear and solid state physics. [including pion absorption spectra and muon spin precession

    NASA Technical Reports Server (NTRS)

    1974-01-01

    The survey of negative pion absorption reactions on light and medium nuclei was continued. Muon spin precession was studied using an iron target. An impulse approximation model of the pion absorption process implied that the ion will absorb almost exclusively on nucleon pairs, single nucleon absorption being suppressed by energy and momentum conservation requirements. For measurements on both paramagnetic and ferromagnetic iron, the external magnetic field was supplied by a large C-type electromagnet carrying a current of about 100 amperes.

  9. Calculation of nuclear-spin-dependent parity nonconservation in s-d transitions of Ba{sup +}, Yb{sup +}, and Ra{sup +} ions

    SciTech Connect

    Dzuba, V. A.; Flambaum, V. V. [School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia)

    2011-05-15

    We use correlation potential and many-body perturbation theory techniques to calculate spin-independent and nuclear-spin-dependent parts of the parity nonconserving amplitudes of the transitions between the 6s{sub 1/2} ground state and the 5d{sub 3/2} excited state of Ba{sup +} and Yb{sup +} and between the 7s{sub 1/2} ground state and the 6d{sub 3/2} excited state of Ra{sup +}. The results are presented in a form convenient for the extracting of the constants of nuclear-spin-dependent interaction (such as, e.g., anapole moment) from the measurements.

  10. Direct observation of low energy nuclear spin excitations in HoCrO3 by high resolution neutron spectroscopy.

    PubMed

    Chatterji, T; Jalarvo, N; Kumar, C M N; Xiao, Y; Brückel, Th

    2013-07-17

    We have investigated low energy nuclear spin excitations in the strongly correlated electron compound HoCrO3. We observe clear inelastic peaks at E = 22.18 ± 0.04 ?eV in both energy loss and gain sides. The energy of the inelastic peaks remains constant in the temperature range 1.5-40 K at which they are observed. The intensity of the inelastic peak increases at first with increasing temperature and then decreases at higher temperatures. The temperature dependence of the energy and intensity of the inelastic peaks is very unusual compared to that observed in other Nd, Co, V and also simple Ho compounds. Huge quasielastic scattering appears at higher temperatures presumably due to the fluctuating electronic moments of the Ho ions that get increasingly disordered at higher temperatures. The strong quasielastic scattering may also originate in the first Ho crystal-field excitations at about 1.5 meV. PMID:23779198

  11. Magnetization transfer modes in scalar-coupled spin systems investigated by selective two-dimensional nuclear magnetic resonance exchange experiments

    NASA Astrophysics Data System (ADS)

    Di Bari, Lorenzo; Kowalewski, Jozef; Bodenhausen, Geoffrey

    1990-12-01

    Longitudinal nuclear magnetic relaxation in coupled two-spin systems is discussed in terms of magnetization transfer modes, a generalization of the magnetization modes commonly used in the discussion of one-dimensional NMR relaxation experiments. The symmetry properties of the transfer modes and their relationship to the elements of the usual Redfield relaxation matrix are discussed. Experimental strategies for measuring the amplitudes of the transfer modes are discussed and various selective two-dimensional exchange (``soft-NOESY'') methods are proposed. Experimental data are presented for Exifone, a small organic molecule, and the auto- and cross-correlation spectral densities, the magnitudes of the proton chemical shift anisotropies, and the strengths of the dipolar interaction are derived from the spectra.

  12. Anti-symmetric spin-orbit force in the effective interaction for the shell model and its effect on nuclear structure

    SciTech Connect

    Tsunoda, N.; Shimizu, N. [Department of Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, I-80126 (Japan); Otsuka, T. [Department of Science, University of Tokyo, 7-3-1, Hongo, Bunkyo-ku, I-80126 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku Tokyo, 113-0033 (Japan) and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI (United States); Suzuki, T. [Department of Physics, College of Humanities and Sciences, Nihon University, Sakurajosui 3, Tokyo 156-8550 (Japan)

    2011-05-06

    Anti-symmetric spin-orbit force (ALS) in the effective interaction for the shell model and its effect on nuclear structure is discussed. We investigate possible origins of the ALS and the effects on the level schemes of several nuclei.

  13. Evolution of nuclear shapes in /sup 157/-/sup 161/Yb as a function of spin and neutron number

    SciTech Connect

    Jaeaeskelaeinen, M.; Sarantites, D.G.; Dilmanian, F.A.; Woodward, R.; Puchta, H.; Beene, J.R.; Hattula, J.; Halbert, M.L.; Hensley, D.C.; Barker, J.H.

    1982-01-01

    The population distributions of the entry states, the entry lines versus multiplicity, the energy spectra and the angular distributions of the continuum ..gamma..-rays as a function of multiplicity in /sup 157/-/sup 161/Yb from the reactions of 136 MeV and 149 MeV /sup 20/Ne with /sup 144/Nd and /sup 146/Nd have been investigated with a 4pi multidetector system gated with a Ge detector. The observed entry lines and ..gamma..-decay modes indicate change for N = 87 - 9l Yb isotopes suggests an evolution of nuclear shapes from prolate at low spins to particle aligned oblate structure for /sup 157/Yb and /sup 158/Yb followed by the onset of high-K bands built on largely deformed oblate states at increasingly higher spin between 38 and 50 n with increasing neutron number for /sup 157/-/sup 161/Yb. Furthermore evidence for an evolution to triaxial shape at I approx. = 50 for /sup 158/Yb was found. 23 references.

  14. The first-principles treatment of the electron-correlation and spin-orbital effects in uranium mononitride nuclear fuels.

    PubMed

    Gryaznov, Denis; Heifets, Eugene; Kotomin, Eugene

    2012-04-01

    The DFT+U calculations were employed in a detailed study of the strong electron correlation effects in a promising nuclear fuel-uranium mononitride (UN). A simple method for solving the multiple minima problem in DFT+U simulations and insure obtaining the correct ground state is suggested and applied. The crucial role of spin-orbit interactions in reproduction of the U atom total magnetic moment is demonstrated. Basic material properties (the lattice constants, the spin- and total magnetic moments on U atoms, the magnetic ordering, and the density of states) were calculated varying the Hubbard U-parameter. By varying the tetragonal unit cell distortion, the meta-stable states have been carefully identified and analyzed. The difference in the magnetic and structural properties obtained for the meta-stable and ground states is discussed. The optimal effective Hubbard parameter U(eff) = 1.85 eV reproduces correctly the UN anti-ferromagnetic ordering, and only slightly overestimates the experimental total magnetic moment of the U atom and the unit cell volume. PMID:22362264

  15. Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: Longitudinal relaxation dispersion for a dipole-coupled spin-1/2 pair

    NASA Astrophysics Data System (ADS)

    Chang, Zhiwei; Halle, Bertil

    2013-10-01

    In complex biological or colloidal samples, magnetic relaxation dispersion (MRD) experiments using the field-cycling technique can characterize molecular motions on time scales ranging from nanoseconds to microseconds, provided that a rigorous theory of nuclear spin relaxation is available. In gels, cross-linked proteins, and biological tissues, where an immobilized macromolecular component coexists with a mobile solvent phase, nuclear spins residing in solvent (or cosolvent) species relax predominantly via exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings. The physical or chemical exchange processes that dominate the MRD typically occur on a time scale of microseconds or longer, where the conventional perturbation theory of spin relaxation breaks down. There is thus a need for a more general relaxation theory. Such a theory, based on the stochastic Liouville equation (SLE) for the EMOR mechanism, is available for a single quadrupolar spin I = 1. Here, we present the corresponding theory for a dipole-coupled spin-1/2 pair. To our knowledge, this is the first treatment of dipolar MRD outside the motional-narrowing regime. Based on an analytical solution of the spatial part of the SLE, we show how the integral longitudinal relaxation rate can be computed efficiently. Both like and unlike spins, with selective or non-selective excitation, are treated. For the experimentally important dilute regime, where only a small fraction of the spin pairs are immobilized, we obtain simple analytical expressions for the auto-relaxation and cross-relaxation rates which generalize the well-known Solomon equations. These generalized results will be useful in biophysical studies, e.g., of intermittent protein dynamics. In addition, they represent a first step towards a rigorous theory of water 1H relaxation in biological tissues, which is a prerequisite for unravelling the molecular basis of soft-tissue contrast in clinical magnetic resonance imaging.

  16. 19F and 31P magic-angle spinning nuclear magnetic resonance of antimony(III)-doped fluorapatite phosphors: Dopant sites and spin diffusion

    NASA Astrophysics Data System (ADS)

    Moran, Liam B.; Berkowitz, Jeffery K.; Yesinowski, James P.

    1992-03-01

    Phosphors based on calcium fluorapatite [Ca5F(PO4)3] doped with small amounts of Sb3+ as an activator are used in most fluorescent lamps. We have used quantitative 19F and 31P magic-angle spinning nuclear magnetic resonance (MAS-NMR) to study seven samples of calcium fluorapatite containing 0.0-3.0 wt % Sb3+ in order to determine the site of antimony substitution. The 31P MAS-NMR spectra of fluorapatite containing 3.0, 2.1, and 1.3 wt % antimony contain a single sharp peak at 2.8 ppm indistinguishable from undoped fluorapatite, and show no additional peaks attributable to the influence of antimony. The 31P MAS-NMR spectra of the model compounds SbPO4, Sr1.03Ca8.97F2(PO4)6, Sr5F(PO4)3, and Ba5F(PO4)3 were also obtained. The 19F MAS-NMR spectra of the antimony-doped samples exhibit, in addition to the main peak at 64.0 ppm (downfield from C6F6) arising from unperturbed fluorapatite, a shoulder at 65.6 ppm, and a sharp peak at 68.6 ppm. The measured spin-lattice relaxation times T1 of these antimony-related peaks are equal in all cases to that of the main peak in a given sample, and vary from 129 to 378 sec, indicating that these peaks arise from apatitic fluoride ions perturbed by antimony. Quantitative studies reveal that the 68.6-ppm peak arises from two fluoride ions and the 65.6-ppm shoulder from one fluoride ion per Sb3+ ion incorporated into the lattice. The selective population anti-z and rate of transfer to adjacent nuclei (SPARTAN) pulse sequence used to measure spin diffusion by selectively inverting the 68.6-ppm peak reveals the presence of cross-relaxation to the main peak at 64.0 ppm, but not to the shoulder at 65.6 ppm. Each Sb3+ ion thus appears to be perturbing fluoride ions in at least two different chains. An additional peak at 73.1 ppm observed in some samples is assigned to a second type of antimony(III) substitution, with a single fluoride ion perturbed by each antimony ion. The results in total provide detailed support for a substitution model in which antimony(III) occupies a phosphate site in the apatite lattice, with a SbO3-3 group replacing a PO3-4 group. Two types of substitution at this site appear to occur, depending upon which oxygen atom is replaced by the antimony lone electron pair.

  17. Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: Longitudinal relaxation dispersion for spin I = 1

    NASA Astrophysics Data System (ADS)

    Nilsson, Tomas; Halle, Bertil

    2012-08-01

    The frequency dependence of the longitudinal relaxation rate, known as the magnetic relaxation dispersion (MRD), can provide a frequency-resolved characterization of molecular motions in complex biological and colloidal systems on time scales ranging from 1 ns to 100 ?s. The conformational dynamics of immobilized proteins and other biopolymers can thus be probed in vitro or in vivo by exploiting internal water molecules or labile hydrogens that exchange with a dominant bulk water pool. Numerous water 1H and 2H MRD studies of such systems have been reported, but the widely different theoretical models currently used to analyze the MRD data have resulted in divergent views of the underlying molecular motions. We have argued that the essential mechanism responsible for the main dispersion is the exchange-mediated orientational randomization (EMOR) of anisotropic nuclear (electric quadrupole or magnetic dipole) couplings when internal water molecules or labile hydrogens escape from orientationally confining macromolecular sites. In the EMOR model, the exchange process is thus not just a means of mixing spin populations but it is also the direct cause of spin relaxation. Although the EMOR theory has been used in several studies to analyze water 2H MRD data from immobilized biopolymers, the fully developed theory has not been described. Here, we present a comprehensive account of a generalized version of the EMOR theory for spin I = 1 nuclides like 2H. As compared to a previously described version of the EMOR theory, the present version incorporates three generalizations that are all essential in applications to experimental data: (i) a biaxial (residual) electric field gradient tensor, (ii) direct and indirect effects of internal motions, and (iii) multiple sites with different exchange rates. In addition, we describe and assess different approximations to the exact EMOR theory that are useful in various regimes. In particular, we consider the experimentally important dilute regime, for which approximate analytical results are derived. As shown by the analytical expressions, and confirmed by exact numerical calculations, the dispersion is governed by the pure nuclear quadrupole resonance frequencies in the ultraslow-motion regime, where the relaxation rate also exhibits a much stronger dependence on the electric field gradient asymmetry than in the motional-narrowing regime.

  18. Solid-State Dynamic Nuclear Polarization at 263 GHz: Spectrometer Design and Experimental Results

    E-print Network

    Rosay, Melanie

    Dynamic Nuclear Polarization (DNP) experiments transfer polarization from electron spins to nuclear spins with microwave irradiation of the electron spins for enhanced sensitivity in nuclear magnetic resonance (NMR) ...

  19. First Step Toward Ultrafast Nuclear-Spin Polarization: All-optical Control and Direct Detection of Ultrafast Electron-Spin Polarization Using Femtosecond Laser Pulses

    SciTech Connect

    Nakajima, Takashi [Institute of Advanced Energy, Kyoto University, Gokasho, Uji, Kyoto 611-0011 (Japan); RIKEN - Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Matsuo, Yukari; Kobayashi, Tohru [RIKEN - Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)

    2009-08-04

    We demonstrate the first experimental observation of ultrafast electron-spin polarization upon photoionization using femtosecond and nanosecond lasers. For the optical detection of electron-spin polarization we measure the laser-induced fluorescence of photoions. The experimental results agree well with our theoretical results obtained by solving the time-dependent Schroedinger equations.

  20. Element-sensitive measurement of the hole-nuclear spin interaction in quantum dots

    NASA Astrophysics Data System (ADS)

    Chekhovich, E. A.; Glazov, M. M.; Krysa, A. B.; Hopkinson, M.; Senellart, P.; Lemaître, A.; Skolnick, M. S.; Tartakovskii, A. I.

    2013-02-01

    It has been proposed that valence-band holes can form robust spin qubits owing to their weaker hyperfine coupling compared with electrons. However, it was demonstrated recently that the hole hyperfine interaction is not negligible, although a consistent picture of the mechanism controlling its magnitude is still lacking. Here we address this problem by measuring the hole hyperfine constant independently for each chemical element in InGaAs/GaAs, InP/GaInP and GaAs/AlGaAs quantum dots. Contrary to existing models we find that the hole hyperfine constant has opposite signs for cations and anions and ranges from -15% to +15% relative to that for electrons. We attribute such changes to the competing positive contributions of p-symmetry atomic orbitals and the negative contributions of d-orbitals. These findings yield information on the orbital composition of the valence band and enable a fundamentally new approach for verification of computed Bloch wavefunctions in semiconductor nanostructures. Furthermore, we show that the contribution of cationic d-orbitals leads to a new mechanism of hole spin decoherence.

  1. Intermediate energy neutrons at WNR. Spin-isospin and energy dependence of the NN interaction and the nuclear response

    SciTech Connect

    Taddeucci, T.N.

    1995-02-01

    This report summarizes results of nuclear physics studies using intermediate energy (50-800 MeV) neutron probes carried out over the past five years using the Neutron Time-of-Flight (NTOF) Facility and Optically-Pumped Ion Source (OPPIS) at LAMPF and the `white` neutron source at the Weapons Neutron Research (WNR) facility. LAMPF did significant work in polarization transfer, while WNR took advantage of the wide neutron energy spectrum available to study energy dependent effects. The major focus of experiments with intermediate energy neutron probes for the next five years will be to explore fundamental details of the spin-isospin and energy dependence of the NN interaction and the nuclear response. To achieve this goal, the WNR white neutron source will be used for nucleon-nucleon and nucleon-nucleus interaction studies over a broad continuous range of incident neutron energy. Measurement of polarization observables using polarized targets or polarized beam should be possible, and will add an important extra dimension to these studies.

  2. Very long nuclear relaxation times of spin polarized helium 3 in metal coated cells

    Microsoft Academic Search

    Werner Heil; Hubert Humblot; Ernst Otten; Matthias Schafer; Reinhard Sarkau; Michèle Leduc

    1995-01-01

    We obtained very long relaxation times T1 of up to 120 h for the nuclear polarization of an optically pumped helium 3 gas. The glass containers were internally coated with metallic films such as bismuth or cesium. These findings will have applications in the field of helium magnetometers and polarized targets.

  3. Observation of Optical Chemical Shift by Precision Nuclear Spin Optical Rotation Measurements and Calculations

    E-print Network

    Romalis, Mike

    and Calculations Junhui Shi, Suvi Ikalainen, Juha Vaara,¶ and Michael V. Romalis*,§ Department of Chemistry The rotation of light polarization is similar to the Faraday effect caused by a nuclear magnetic field to Faraday rotation changes by more than a factor of 2 for the simple chemicals studied. We apply the recent

  4. Effect of nuclear spin on chemical reactions and internal molecular rotation

    SciTech Connect

    Sterna, L.L.

    1980-12-01

    Part I of this dissertation is a study of the magnetic isotope effect, and results are presented for the separation of /sup 13/C and /sup 12/C isotopes. Two models are included in the theoretical treatment of the effect. In the first model the spin states evolve quantum mechanically, and geminate recombination is calculated by numerically integrating the collision probability times the probability the radical pair is in a singlet state. In the second model the intersystem crossing is treated via first-order rate constants which are average values of the hyperfine couplings. Using these rate constants and hydrodynamic diffusion equations, an analytical solution, which accounts for all collisions, is obtained for the geminate recombination. The two reactions studied are photolysis of benzophenone and toluene and the photolytic decomposition of dibenzylketone (1,3-diphenyl-2-propanone). No magnetic isotope effect was observed in the benzophenone reaction. /sup 13/C enrichment was observed for the dibenzylketone reaction, and this enrichment was substantially enhanced at intermediate viscosities and low temperatures. Part II of this dissertation is a presentation of theory and results for the use of Zeeman spin-lattice relaxation as a probe of methyl group rotation in the solid state. Experimental results are presented for the time and angular dependences of rotational polarization, the methyl group magnetic moment, and methyl-methyl steric interactions. The compounds studied are 2,6-dimethylphenol, methyl iodide, 1,4,5,8-tetramethylanthracene, 1,4,5,8-tetramethylnaphthalene, 1,2,4,5-tetramethylbenzene, and 2,3-dimethylmaleicanhydride.

  5. Nuclear magnetic resonance data of C16H25AsS3

    NASA Astrophysics Data System (ADS)

    Mikhova, B. M.

    This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  6. Nuclear magnetic resonance data of C15H23AsS2

    NASA Astrophysics Data System (ADS)

    Mikhova, B. M.

    This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  7. Long-time behavior of nuclear spin decays in various lattices

    SciTech Connect

    Sorte, E. G.; Saam, B. [Department of Physics, University of Utah, 115 South 1400 East, Salt Lake City, UT 84112-0830 (United States); Fine, B. V. [Institute of Theoretical Physics, University of Heidelberg, Philosophenweg 19, 69120 Heidelberg (Germany)

    2011-02-01

    The transverse NMR decays of {sup 129}Xe in polycrystalline xenon were recently shown to have a universal property: in the long-time regime these decays all converge to the same sinusoidally modulated exponential function irrespective of the initial transverse spin configuration prepared by a sequence of one or more radio frequency pulses. The present work constitutes a more comprehensive survey of this phenomenon. It examines transverse decays for several different isotopic concentrations of {sup 129}Xe, employs additional pulse sequences, and performs similar measurements in a different material: {sup 19}F in single-crystal and polycrystalline CaF{sub 2}. With the possible exception of polycrystalline CaF{sub 2} where the observation of the long-time behavior is limited by the experimental resolution, all these systems display the long-time universal behavior characterized by particular values of the exponential decay coefficient and beat frequency that were unique for each lattice. This behavior has been theoretically predicted based on the notion of microscopic chaos.

  8. Mechanism of nuclear spin-lattice relaxation and its field dependence for ultraslow atomic motion

    SciTech Connect

    Mefed, A. E. [Russian Academy of Sciences, Fryazino Branch, Kotel'nikov Institute of Radio Engineering and Electronics (Russian Federation)], E-mail: aem228@ire216.msk.su

    2008-10-15

    The contribution of ultraslow self-diffusion of polycrystalline benzene molecules to the spin-lattice relaxation of protons is studied as a function of effective magnetic field H{sub 2} in a doubly rotating frame (DRF). Proton relaxation time T{sub 1{rho}}{sub {rho}} is measured by direct recording of NMR in a rotating frame (RF). The effective fields have a 'magic' orientation corresponding to angles arccos(1/{radical}3) in the RF and {pi}/2 in the DRF so that the secular part of the dipole-dipole interactions of protons is suppressed in two orders of perturbation theory, while the nonsecular part becomes predominant. It is found that the diffusion contribution of benzene molecules to proton relaxation time T{sub 1{rho}}{sub {rho}} is a linear function of the square of field H{sub 2} and exhibits all peculiarities typical of the model of strong collisions generalized to only fluctuating nonsecular dipole interactions in fields exceeding the local field. This means that the model can also be employed in the given conditions. It is shown that perfect agreement with such a dependence can also be obtained in the model of weak collisions if we take into account the concept of the locally effective quantization field, whose magnitude and direction are controlled by the vector sum of field H{sub 2}, and the nonsecular local field perpendicular to it.

  9. Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization

    SciTech Connect

    Lafon, Olivier [Universite de Lille Nord de France; Thankamony, Aany S. Lilly [Universite de Lille Nord de France; Kokayashi, Takeshi [Ames Laboratory; Carnevale, Diego [Ecole Polytechnique Federale de Lausanne; Vitzthum, Veronika [Ecole Polytechnique Federale de Lausanne; Slowing, Igor I. [Ames Laboratory; Kandel, Kapil [Ames Laboratory; Vezin, Herve [Universite de Lille Nord de France; Amoureux, Jean-Paul [Universite de Lille Nord de France; Bodenhausen, Geoffrey [Ecole Polytechnique Federale de Lausanne; Pruski, Marek [Ames Laboratory

    2012-12-21

    We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H–1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements ?on/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to ?on/off ? 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.

  10. Evaluation of nitrogen nuclear hyperfine and quadrupole coupling parameters for the proximal imidazole in myoglobin-azide, -cyanide, and -mercaptoethanol complexes by electron spin echo envelope modulation spectroscopy.

    PubMed

    Magliozzo, R S; Peisach, J

    1993-08-24

    Electron spin echo envelope modulation (ESEEM) spectroscopy and computer simulation of spectra has been used to evaluate the nitrogen nuclear hyperfine and quadrupole coupling parameters for the proximal imidazole nitrogen directly coordinated to iron in three low-spin heme complexes, myoglobin-azide, -cyanide, and -mercaptoethanol (MbN3, MbCN, and MbRS). The variability in the weak electron-nuclear coupling parameters reveals the electronic flexibility within the heme group that depends on properties of the exogenous ligands. For example, the isotropic component of the nitrogen nuclear hyperfine coupling ranges from 4.4 MHz for MbN3 to 2.2 MHz for both MbCN and MbRS. The weaker coupling in MbCN and MbRS is taken as evidence for delocalization of unpaired electron spin from iron into the exogenous anionic ligands. The value of e2Qq, the nuclear quadrupole coupling constant for the axial imidazole nitrogen in MbCN and MbRS, was 2.5 MHz but was significantly larger, 3.2 MHz, in MbN3. This large value is considered evidence for a weakened sigma bond between the proximal imidazole and ferric iron in this form, and for a feature contributing to the origin of the high spin-low spin equilibrium exhibited by MbN3 [Beetlestone, J., & George, P. (1964) Biochemistry 5, 707-714]. The ESEEM results have allowed a correlation to be made between the orientation of the g tensor axes, the orientation of the p-pi orbital of the proximal imidazole nitrogen, and sigma- and pi-bonding features of the axial ligands. Furthermore, the proximal imidazole is suggested to act as a pi-acceptor in low-spin heme complexes in order to support strong sigma electron donation from the lone pair orbital to iron. An evaluation of the nitrogen nuclear hyperfine coupling parameters for the porphyrin pyrrole sites in MbRS reveals a large inequivalence in isotropic components consistent with an orientation of rhombic axes (and g tensor axes) that eclipses the Fe-Npyrrole vector directions. PMID:8395204

  11. Nuclear magnetic resonance spectra for l > 1 spins in dynamically heterogeneous systems with chemical exchange among environments.

    PubMed Central

    Zhang, H; Bryant, R G

    1995-01-01

    Nuclear magnetic resonance spectra for nuclei with spin l > 1 are considered in cases in which the observed nucleus may sample a rotationally immobilized and an isotropic environment that are coupled by a chemical exchange process. Spectra are simulated for the central (1/2, -1/2) transition for a 3/2 nucleus as a function of the concentrations of the two environments and as a function of the exchange rate between them. It is shown that a crucial feature determining the shape of the observable spectra is the spatial extent or the local order in the immobilized phase. In the case for which all rotationally immobilized sites sampled by the exchanging nucleus are identically oriented but where there is a distribution of these microdomain orientations with respect to the magnetic field direction, a powder pattern for the central transition is observed that carries whatever dynamic information may be derived from it. In the fast exchange limit, the width of the powder pattern scales inversely with the concentration of the isotropic environment as usual. In the intermediate exchange regimes, a complex line shape results that may mask the anisotropic character of the spectrum. In the slow exchange limit, superposition of the spectral contributions results; however, if the isotropic environment concentration is significantly larger than the anisotropic environment concentration, the anisotropic contribution is very difficult to detect because of the dynamic range problem and the possibly large difference in the effective line widths. In the case for which the exchanging nucleus samples a considerable distribution of rotationally immobilized site orientations, the anisotropic character of the spectrum is lost and a super-Lorentzian line shape results. These effects are demonstrated experimentally by 35Cl nuclear magnetic resonance spectra obtained on a lamellar liquid crystal that is modified with the addition of a thiolmercurate to provide a site of large quadrupole coupling constant and with cross-linked bovine serum albumin gels. PMID:7647258

  12. Tweezers for parahydrogen: a metal-free probe of nonequilibrium nuclear spin states of H? molecules.

    PubMed

    Zhivonitko, Vladimir V; Telkki, Ville-Veikko; Chernichenko, Konstantin; Repo, Timo; Leskelä, Markku; Sumerin, Victor; Koptyug, Igor V

    2014-01-15

    To date, only metal-containing hydrogenation catalysts have been utilized for producing substantial NMR signal enhancements by means of parahydrogen-induced polarization (PHIP). Herein, we show that metal-free compounds known as molecular tweezers are useful in this respect. It is shown that ansa-aminoborane tweezers QCAT provided (20-30)-fold signal enhancements of parahydrogen-originating hydrogens in (1)H NMR spectra. Nuclear polarization transfer from the polarized hydrogens to (11)B nuclei leads to a 10-fold enhancement in the (11)B NMR spectrum. Moreover, our results indicate that dihydrogen activation by QCAT and CAT tweezers is carried out in a pairwise manner, and PHIP can be used for understanding the activation mechanism in metal-free catalytic systems in general. PMID:24359087

  13. THE LOW-TEMPERATURE NUCLEAR SPIN EQUILIBRIUM OF H{sup +} {sub 3} IN COLLISIONS WITH H{sub 2}

    SciTech Connect

    Grussie, F.; Berg, M. H.; Wolf, A.; Kreckel, H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Crabtree, K. N.; McCall, B. J. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Gaertner, S.; Schlemmer, S., E-mail: holger.kreckel@mpi-hd.mpg.de [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany)

    2012-11-01

    Recent observations of H{sub 2} and H{sup +} {sub 3} in diffuse interstellar sightlines revealed a difference in the nuclear spin excitation temperatures of the two species. This discrepancy comes as a surprise, as H{sup +} {sub 3} and H{sub 2} should undergo frequent thermalizing collisions in molecular clouds. Non-thermal behavior of the fundamental H{sup +} {sub 3}/H{sub 2} collision system at low temperatures was considered as a possible cause for the observed irregular populations. Here, we present measurements of the steady-state ortho/para ratio of H{sup +} {sub 3} in collisions with H{sub 2} molecules in a temperature-variable radiofrequency ion trap between 45 and 100 K. The experimental results are close to the expected thermal outcome and they agree very well with a previous micro-canonical model. We briefly discuss the implications of the experimental results for the chemistry of the diffuse interstellar medium.

  14. Nuclear spin dependence of the reaction of H{sub 3}{sup +} with H{sub 2}. II. Experimental measurements

    SciTech Connect

    Crabtree, Kyle N.; Kauffman, Carrie A.; Tom, Brian A.; Becka, Eftalda; McGuire, Brett A. [Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States); McCall, Benjamin J. [Departments of Chemistry, Astronomy, and Physics, University of Illinois, Urbana, Illinois 61801 (United States)

    2011-05-21

    The nuclear spin dependence of the chemical reaction H{sub 3}{sup +}+ H{sub 2}{yields} H{sub 2} +H{sub 3}{sup +} has been studied in a hollow cathode plasma cell. Multipass infrared direct absorption spectroscopy has been employed to monitor the populations of several low-energy rotational levels of ortho- and para-H{sub 3}{sup +} (o-H{sub 3}{sup +} and p-H{sub 3}{sup +}) in hydrogenic plasmas of varying para-H{sub 2} (p-H{sub 2}) enrichment. The ratio of the rates of the proton hop (k{sup H}) and hydrogen exchange (k{sup E}) reactions {alpha}{identical_to}k{sup H}/k{sup E} is inferred from the observed p-H{sub 3}{sup +} fraction as a function of p-H{sub 2} fraction using steady-state chemical models. Measurements have been performed both in uncooled (T{sub kin}{approx} 350 K) and in liquid-nitrogen-cooled (T{sub kin}{approx} 135 K) plasmas, marking the first time this reaction has been studied at low temperature. The value of {alpha} has been found to decrease from 1.6 {+-} 0.1 at 350 K to 0.5 {+-} 0.1 at 135 K.

  15. Radiation-induced oxidation and reduction of guanine: Electron spin resonance--electron nuclear double resonance studies of irradiated guanosine cyclic monophosphate

    SciTech Connect

    Kim, H.; Budzinski, E.E.; Box, H.C.

    1989-02-01

    Two free radicals are identified by electron spin resonance--electron nuclear double resonance (ESR-ENDOR) spectroscopy in single crystals of guanosine 3',5'-cyclic monophosphate x irradiated at 4.2 K. The two absorptions are attributed to the anion and cation formed on the guanine moiety. The characteristics of the cation absorption are consistent with those postulated previously for guanine cation presumed to form in irradiated DNA.

  16. Nuclear spin dependence of the reaction of H{sub 3}{sup +} with H{sub 2}. I. Kinetics and modeling

    SciTech Connect

    Crabtree, Kyle N.; Tom, Brian A. [Department of Chemistry, University of Illinois, Urbana, Illinois 61801 (United States); McCall, Benjamin J. [Departments of Chemistry, Astronomy, and Physics, University of Illinois, Urbana, Illinois 61801 (United States)

    2011-05-21

    The chemical reaction H{sub 3}{sup +}+ H{sub 2}{yields} H{sub 2}+H{sub 3}{sup +} is the simplest bimolecular reaction involving a polyatomic, yet is complex enough that exact quantum mechanical calculations to adequately model its dynamics are still unfeasible. In particular, the branching fractions for the ''identity,''''proton hop,'' and ''hydrogen exchange'' reaction pathways are unknown, and to date, experimental measurements of this process have been limited. In this work, the nuclear-spin-dependent steady-state kinetics of the H{sub 3}{sup +}+ H{sub 2} reaction is examined in detail, and employed to generate models of the ortho:para ratio of H{sub 3}{sup +} formed in plasmas of varying ortho:para H{sub 2} ratios. One model is based entirely on nuclear spin statistics, and is appropriate for temperatures high enough to populate a large number of H{sub 3}{sup +} rotational states. Efforts are made to include the influence of three-body collisions in this model by deriving nuclear spin product branching fractions for the H{sub 5}{sup +}+ H{sub 2} reaction. Another model, based on rate coefficients calculated using a microcanonical statistical approach, is appropriate for lower-temperature plasmas in which energetic considerations begin to compete with the nuclear spin branching fractions. These models serve as a theoretical framework for interpreting the results of laboratory studies on the reaction of H{sub 3}{sup +} with H{sub 2}.

  17. Carbon-13 Labeled Polymers: An Alternative Tracer for Depth Profiling of Polymer Films and

    E-print Network

    . Mass spectra of 13C-PS and 12C-PS were also analyzed using a PHI TRIFT I time-of-flight mass spec forward recoil spec- trometry (FRES),7 nuclear reaction analysis (NRA),8 and second- ary ion mass and Multilayers Using Secondary Ion Mass Spectrometry S. E. Harton, F. A. Stevie, Z. Zhu, and H. Ade*,§ Department

  18. Detection of a Spin-Triplet Superconducting Phase in Oriented Polycrystalline U_{2}PtC_{2} Samples Using ^{195}Pt Nuclear Magnetic Resonance.

    PubMed

    Mounce, A M; Yasuoka, H; Koutroulakis, G; Ni, N; Bauer, E D; Ronning, F; Thompson, J D

    2015-03-27

    Nuclear magnetic resonance (NMR) measurements on the ^{195}Pt nucleus in an aligned powder of the moderately heavy-fermion material U_{2}PtC_{2} are consistent with spin-triplet pairing in its superconducting state. Across the superconducting transition temperature and to much lower temperatures, the NMR Knight shift is temperature independent for field both parallel and perpendicular to the tetragonal c axis, expected for triplet equal-spin pairing superconductivity. The NMR spin-lattice relaxation rate 1/T_{1}, in the normal state, exhibits characteristics of ferromagnetic fluctuations, compatible with an enhanced Wilson ratio. In the superconducting state, 1/T_{1} follows a power law with temperature without a coherence peak giving additional support that U_{2}PtC_{2} is an unconventional superconductor. Bulk measurements of the ac susceptibility and resistivity indicate that the upper critical field exceeds the Pauli limiting field for spin-singlet pairing and is near the orbital limiting field, an additional indication for spin-triplet pairing. PMID:25860768

  19. Comparison of Solid-State Carbon13 Nuclear Magnetic Resonance and Organic Matter Biomarkers for Assessing Soil Organic Matter Degradation

    Microsoft Academic Search

    Myrna J. Simpson; Angelika Otto; Xiaojuan Feng

    2008-01-01

    Soil organic matter (SOM) is a heterogeneous mixture of compounds that are derived from a number of sources. Therefore, trying to assess the stage of SOM alteration is challeng- ing. Recently, our research has proposed a number of degradation parameters based on the measurement of SOM biomarkers. These biomarkers, which can be attributed to a specifi c organism source and

  20. STRUCTURES OF SOME KEPONE PHOTOPRODUCTS AND RELATED CHLORINATED PENTACYCLODECANES BY CARBON-13 AND PROTON NUCLEAR MAGNETIC RESONANCE

    EPA Science Inventory

    The pesticide Kepone, 1,1a,3,3a,4,5,5a,5b,6-decachlorooctahydro-1,3,4-metheno-2H-cyclobuta(cd)pentalen-2-one, the related compounds mirex, kelevan, a monohydro photoproduct of kelevan, kepone alcohol, kepone hydrate, and the mono- and dihydro photoproducts of Kepone hydrate and t...

  1. Indole alkaloids of Rauwolfia reflexa. Carbon-13 nuclear magnetic resonance structural analysis of the bis(indole) alkaloid flexicorine

    SciTech Connect

    Chatterjee, A. (Univ. College of Science, Calcutta, India); Ghosh, A.K.; Hagaman, E.W.

    1982-01-01

    The /sup 13/C NMR spectra analysis of the new bis(indole) alkaloid flexicorine and of its chemically modified derivatives were used to determine the structure of the natural base. Flexicorine is, apparently, the first 10'-hydroxy N'-unsubstituted indoline which preferentially exists in the original iminoquinone form. 2 tables.

  2. Indole alkaloids of Rauwolfia reflexa. Carbon13 nuclear magnetic resonance structural analysis of the bis(indole) alkaloid flexicorine

    Microsoft Academic Search

    A. Chatterjee; A. K. Ghosh; E. W. Hagaman

    1982-01-01

    The ¹³C NMR spectra analysis of the new bis(indole) alkaloid flexicorine and of its chemically modified derivatives were used to determine the structure of the natural base. Flexicorine is, apparently, the first 10'-hydroxy N'-unsubstituted indoline which preferentially exists in the original iminoquinone form. 2 tables.

  3. CARBON-13 NUCLEAR MAGNETIC RESONANCE. 13C CHEMICAL SHIFTS AND 13C-199HG COUPLING CONSTANTS FOR SOME ORGANOMERCURY COMPOUNDS

    EPA Science Inventory

    The (13)C shieldings and (13)C-(199)Hg coupling constants of fourteen phenyl- and seven alkyl- and alkenyl-mercury compounds have been obtained. Substituent effects on the (13)C shieldings are similar to those in nonmercurated phenyl compounds, with a similar relationship between...

  4. Nuclear Spin Effects in the Reactions of H3^+ with H2 and Electrons

    NASA Astrophysics Data System (ADS)

    Kreckel, Holger; Crabtree, Kyle; Kauffman, Carrie; Tom, Brian; Novotny, Oldrich; Berg, Max; Bing, Dennis; Buhr, Henrik; Krantz, Claude; Lestinsky, Michael; Mendes, Mario; Nordhorn, Christian; Stutzel, Julia; Wolf, Andreas; Thomas, Richard; McCall, Benjamin

    2010-03-01

    H3^+ is the simplest polyatomic molecule. It is widely used as a benchmark for theoretical calculations of molecular spectroscopy and reaction dynamics, and also plays a pivotal role as the cornerstone of interstellar chemistry. In Urbana, we have investigated the proton hop/exchange reaction H3^+ + H2 -> (H5^+)^* -> H2 + H3^+ for the first time at low temperatures. This reaction is the simplest bimolecular reaction involving a polyatomic, and is also the most common bimolecular reaction in the universe. Our experiments have revealed the branching ratio between proton hop and exchange, and appear to explain the observed ortho:para ratio of H3^+ in diffuse interstellar clouds. At the TSR storage ring of the Max Planck Institute for Nuclear Physics in Heidelberg, we have performed high-resolution measurements of the dissociative recombination (DR) cross sections of cold H3^+ in different mixtures of its lowest ortho and para quantum states. These measurements represent an important step towards the first state-selected DR measurements.

  5. Using Bio-Functionalized Magnetic Nanoparticles and Dynamic Nuclear Magnetic Resonance to Characterize the Time-Dependent Spin-Spin Relaxation Time for Sensitive Bio-Detection

    PubMed Central

    Liao, Shu-Hsien; Chen, Kuen-Lin; Wang, Chun-Min; Chieh, Jen-Jie; Horng, Herng-Er; Wang, Li-Min; Wu, C. H.; Yang, Hong-Chang

    2014-01-01

    In this work, we report the use of bio-functionalized magnetic nanoparticles (BMNs) and dynamic magnetic resonance (DMR) to characterize the time-dependent spin-spin relaxation time for sensitive bio-detection. The biomarkers are the human C-reactive protein (CRP) while the BMNs are the anti-CRP bound onto dextran-coated Fe3O4 particles labeled as Fe3O4-antiCRP. It was found the time-dependent spin-spin relaxation time, T2, of protons decreases as time evolves. Additionally, the ?T2 of of protons in BMNs increases as the concentration of CRP increases. We attribute these to the formation of the magnetic clusters that deteriorate the field homogeneity of nearby protons. A sensitivity better than 0.1 ?g/mL for assaying CRP is achieved, which is much higher than that required by the clinical criteria (0.5 mg/dL). The present MR-detection platform shows promise for further use in detecting tumors, viruses, and proteins. PMID:25397920

  6. Using bio-functionalized magnetic nanoparticles and dynamic nuclear magnetic resonance to characterize the time-dependent spin-spin relaxation time for sensitive bio-detection.

    PubMed

    Liao, Shu-Hsien; Chen, Kuen-Lin; Wang, Chun-Min; Chieh, Jen-Jie; Horng, Herng-Er; Wang, Li-Min; Wu, C H; Yang, Hong-Chang

    2014-01-01

    In this work, we report the use of bio-functionalized magnetic nanoparticles (BMNs) and dynamic magnetic resonance (DMR) to characterize the time-dependent spin-spin relaxation time for sensitive bio-detection. The biomarkers are the human C-reactive protein (CRP) while the BMNs are the anti-CRP bound onto dextran-coated Fe3O4 particles labeled as Fe3O4-antiCRP. It was found the time-dependent spin-spin relaxation time, T2, of protons decreases as time evolves. Additionally, the ?T2 of of protons in BMNs increases as the concentration of CRP increases. We attribute these to the formation of the magnetic clusters that deteriorate the field homogeneity of nearby protons. A sensitivity better than 0.1 ?g/mL for assaying CRP is achieved, which is much higher than that required by the clinical criteria (0.5 mg/dL). The present MR-detection platform shows promise for further use in detecting tumors, viruses, and proteins. PMID:25397920

  7. Isotopic multiplets in the carbon-13 NMR spectra of aniline derivatives and nucleosides with partially deuterated amino groups: effects of intra- and intermolecular hydrogen bonding

    SciTech Connect

    Reuben, J.

    1987-01-21

    In aniline derivatives, the carbon-13 resonances of atoms bearing partially deuterated amino groups, as well as the resonances of vicinal carbon atoms, appear as multiplets. This phenomenon, which is due to upfield deuterium isotope effects on carbon-13 chemical shifts, is observed under conditions of slow hydrogen exchange (e.g., in Me/sub 2/SO solutions). The effects are larger for groups engaged in intramolecular hydrogen bonds. Empirical expressions are presented that relate isotope effects with amino proton chemical shifts and hydrogen bond energies. Isotopic multiplets are also observed in the carbon-13 NMR spectra of partially deuterated nucleosides. The multiplet structure is altered upon formation of base pairs. These results are interpreted in terms of hydrogen exchange reactions involving uridine (or thymidine) hydrogen-bonded dimers or changes in hydrogen bond energies upon formation of guanosine-cytidine complexes. Estimates are given for the energies of individual hydrogen bonds in Watson-Crick base pairs.

  8. Intermediate energy spin physics. Appendix 6

    SciTech Connect

    Igo, G.

    1983-01-01

    Topics include nuclear information from proton spin observables in elastic scattering, nuclear information from proton spin observables in inelastic scattering, recent measurements at the HRS utilizing a focal plane polarimeter, proton spin observables in natural parity transitions, and proton spin transfer observables in unnatural parity transitions. 47 references.

  9. Nitrogen nuclear spin flips in nitroxide spin probes of different sizes in glassy o-terphenyl: Possible relation with alpha- and beta-relaxations

    Microsoft Academic Search

    N. P. Isaev; S. A. Dzuba

    2011-01-01

    The pulsed electron-electron double resonance (ELDOR) technique was employed to study nitroxide spin probes of three different sizes dissolved in glassy o-terphenyl. A microwave pulse applied to the central hyperfine structure (hfs) component of the nitroxide electron paramagnetic resonance spectrum was followed by two echo-detecting pulses of different microwave frequency to probe the magnetization transfer (MT) to the low-field hfs

  10. Nitrogen nuclear spin flips in nitroxide spin probes of different sizes in glassy o-terphenyl: Possible relation with ?- and ?-relaxations

    Microsoft Academic Search

    N. P. Isaev; S. A. Dzuba

    2011-01-01

    The pulsed electron-electron double resonance (ELDOR) technique was employed to study nitroxide spin probes of three different sizes dissolved in glassy o-terphenyl. A microwave pulse applied to the central hyperfine structure (hfs) component of the nitroxide electron paramagnetic resonance spectrum was followed by two echo-detecting pulses of different microwave frequency to probe the magnetization transfer (MT) to the low-field hfs

  11. A nuclear magnetic resonance spectrometer concept for hermetically sealed magic angle spinning investigations on highly toxic, radiotoxic, or air sensitive materials

    NASA Astrophysics Data System (ADS)

    Martel, L.; Somers, J.; Berkmann, C.; Koepp, F.; Rothermel, A.; Pauvert, O.; Selfslag, C.; Farnan, I.

    2013-05-01

    A concept to integrate a commercial high-resolution, magic angle spinning nuclear magnetic resonance (MAS-NMR) probe capable of very rapid rotation rates (70 kHz) in a hermetically sealed enclosure for the study of highly radiotoxic materials has been developed and successfully demonstrated. The concept centres on a conventional wide bore (89 mm) solid-state NMR magnet operating with industry standard 54 mm diameter probes designed for narrow bore magnets. Rotor insertion and probe tuning take place within a hermetically enclosed glovebox, which extends into the bore of the magnet, in the space between the probe and the magnet shim system. Oxygen-17 MAS-NMR measurements demonstrate the possibility of obtaining high quality spectra from small sample masses (˜10 mg) of highly radiotoxic material and the need for high spinning speeds to improve the spectral resolution when working with actinides. The large paramagnetic susceptibility arising from actinide paramagnetism in (Th1-xUx)O2 solid solutions gives rise to extensive spinning sidebands and poor resolution at 15 kHz, which is dramatically improved at 55 kHz. The first 17O MAS-NMR measurements on NpO2+x samples spinning at 55 kHz are also reported. The glovebox approach developed here for radiotoxic materials can be easily adapted to work with other hazardous or even air sensitive materials.

  12. Mixing of parity of a nucleon pair at the nuclear surface due to the spin-orbit potential in 18F

    NASA Astrophysics Data System (ADS)

    Kanada-En'yo, Yoshiko; Kobayashi, Fumiharu

    2014-11-01

    We investigate the structure of 18F with the microscopic wave function based on the three-body 16O+p +n model. In the calculation of the generator coordinate method of the three-body model, T =0 energy spectra of J?=1+ ,3+, and 5+ states and T =1 spectra of J?=0+ ,2+ states in 18F are described reasonably. Based on the dinucleon picture, the effect of the spin-orbit force on the T =0 and T =1 p n pairs around the 16O core is discussed. The T =1 pair in the J?=0+ state gains the spin-orbit potential energy involving the odd-parity mixing in the pair. The spin-orbit potential energy gain with the parity mixing is not so efficient for the T =0 pair in the J?=1+ state. The parity mixing in the pair is regarded as the internal symmetry breaking of the pair in the spin-orbit potential at the nuclear surface.

  13. Nuclear Quadrupole Resonance and Electron Spin Resonance in C(NH2)3Al(SO4)2.6H2O and Isomorphous Compounds

    Microsoft Academic Search

    Gerald Burns

    1961-01-01

    The temperature dependence of the nuclear quadrupole coupling parameters, eQqh, of Al and Ga has been measured in the ferroelectric compound C(NH2)3Al(SO4)2.6H2O (GAlSH) and three other isomorphous compounds that result when Ga replaces Al and SeO4 replaces SO4. Measurements were also made on deuterated GAlSH. The temperature dependence of the electron spin resonance (ESR) of Cr3+, substituted for Al or

  14. Intermolecular Structure Determination of Amyloid Fibrils with 2 Magic-Angle Spinning and Dynamic Nuclear Polarization NMR

    E-print Network

    Bayro, Marvin J.

    We describe magic-angle spinning NMR experiments designed to elucidate the interstrand architecture of amyloid fibrils. Three methods are introduced for this purpose, two being based on the analysis of long-range [superscript ...

  15. THE EFFECTS OF PARAMAGNETIC RELAXATION REAGENTS ON 15N SPIN RELAXATION AND THE USE OF GD(DPM)3 AS A NITROGEN-15 NUCLEAR MAGNETIC RESONANCE SPIN LABEL

    EPA Science Inventory

    Electron-nuclear relaxation times (T(1) sup e's) for (15)N and (13)C in natural abundance are measured for a series of amines of a wide range of pK(a)s using four paramagnetic relaxation reagents that are soluable in organic solutions. Cr(acac)3 and Cr(dpm)3 are seen to affect th...

  16. Twelve-spin "Schrodinger cat"

    E-print Network

    Jae-Seung Lee; A. K. Khitrin

    2005-08-01

    Pseudopure "cat" state, a superposition of quantum states with all spins up and all spins down, is experimentally demonstrated for a system of twelve dipolar-coupled nuclear spins of fully 13C-labeled benzene molecule oriented in a liquid-crystalline matrix.

  17. Nuclear quadrupole spin-lattice relaxation in Bi{sub 4}Ge{sub 3}O{sub 12} single crystals doped with atoms of d or f elements. Crystal field effects in compounds exhibiting anomalous magnetic properties

    SciTech Connect

    Orlov, V. G., E-mail: orlov@mbslab.kiae.ru; Sergeev, G. S. [Russian Research Center 'Kurchatov Institute' (Russian Federation); Asaji, Tetsuo [Nihon University, Department of Chemistry, College of Humanities and Sciences (Japan); Kravchenko, E. A. [Russian Academy of Sciences, Institute of General and Inorganic Chemistry (Russian Federation); Kargin, Yu. F. [Russian Academy of Sciences, State Institute of Metallurgy and Material Science (Russian Federation)

    2010-02-15

    The nuclear quadrupole spin-lattice relaxation was studied in the range 4.2-300 K for single crystals of Bi{sub 4}Ge{sub 3}O{sub 12} doped with minor amounts (the tenth fractions of mol%) of paramagnetic atoms of Cr, Nd, and Gd. Unusual spin dynamic features were recently found for these crystals at room temperature: a dramatic (up to 8-fold) increase in the effective nuclear quadrupole spin-spin relaxation time T{sub 2}* occurred upon doping the pure Bi{sub 4}Ge{sub 3}O{sub 12} sample. Unlike T{sub 2}*, the effective spin-lattice relaxation time T{sub 1}* at room temperature differs insignificantly for both doped and pure samples. But at lower temperatures, the samples exhibit considerably different behavior of the spin-lattice relaxation with temperature, which is caused by different contributions to the relaxation process of the dopant paramagnetic atoms. The distinctive maximum in the temperature dependence of the spin-lattice relaxation time for the Nd-doped crystal is shown to result from the crystal electric field effects.

  18. PHYSICAL REVIEW B 90, 085311 (2014) All-optical NMR in semiconductors provided by resonant cooling of nuclear spins interacting

    E-print Network

    Suter, Dieter

    the polarization of the photoluminescence [4­9] or as Faraday and Kerr rotation [10] (for reviews see Refs. [11-oriented electrons in semiconductors. All-optical NMR has also been realized on the basis of the time-resolved pump-probe Faraday/Kerr rotation technique, where the coherent Larmor precession of the electron spins is detected

  19. Carbon13 NMR spectroscopy

    Microsoft Academic Search

    E. Breitmaier; W. Voelter

    1987-01-01

    Features in this edition are references (over 1,000), profuse illustration, a discussion of modern pulse techniques for spectral analysis, and extensive and thorough cataloguing of chemical shift data (over 200 pages) in readily accessible form. An attractive feature is the use of structural formulae with shifts inscribed in the structure. This new edition has been completely revised to take into

  20. Spatial and Temporal Variations in Stable Carbon (?13C) and Nitrogen (?15N) Isotopic Composition of Symbiotic Scleractinian Corals

    PubMed Central

    Nahon, Sarah; Richoux, Nicole B.; Kolasinski, Joanna; Desmalades, Martin; Ferrier Pages, Christine; Lecellier, Gael; Planes, Serge; Berteaux Lecellier, Véronique

    2013-01-01

    Tropical scleractinian corals are considered autotrophic as they rely mainly on photosynthesis-derived nutrients transferred from their photosymbionts. Corals are also able to capture and ingest suspended particulate organic matter, so heterotrophy can be an important supplementary trophic pathway to optimize coral fitness. The aim of this in situ study was to elucidate the trophic status of 10 coral species under contrasted environmental conditions in a French Polynesian lagoon. Carbon (?13C) and nitrogen (?15N) isotopic compositions of coral host tissues and photosymbionts were determined at 3 different fringing reefs during wet and dry seasons. Our results highlighted spatial variability in stable isotopic compositions of both coral host tissues and photosymbionts. Samples from the site with higher level of suspended particulate matter were 13C-depleted and 15N-enriched relative to corals and photosymbionts from less turbid sites. However, differences in both ?13C and ?15N between coral host tissues and their photosymbionts (?host-photosymbionts 13C and ?host-photosymbionts 15N) were small (0.27 ± 0.76‰ and 1.40 ± 0.90‰, respectively) and similar at all sites, thus indicating no general increases in the heterotrophic pathway. Depleted ?13C and enriched ?15N values of coral host tissues measured at the most turbid site were explained by changes in isotopic composition of the inorganic nutrients taken up by photosymbionts and also by changes in rate of isotopic fractionation with environmental conditions. Our results also highlighted a lack of significant temporal variations in ?13C and ?15N values of coral host and photosymbiont tissues and in ?host-photosymbionts 13C and ?host-photosymbionts 15N values. This temporal stability indicated that corals remained principally autotrophic even during the wet season when photosymbiont densities were lower and the concentrations of phytoplankton were higher. Increased coral heterotrophy with higher food availability thus appears to be species-specific. PMID:24312542

  1. Spatial and temporal variations in stable carbon (?(13)C) and nitrogen (?(15)N) isotopic composition of symbiotic scleractinian corals.

    PubMed

    Nahon, Sarah; Richoux, Nicole B; Kolasinski, Joanna; Desmalades, Martin; Ferrier Pages, Christine; Lecellier, Gael; Planes, Serge; Berteaux Lecellier, Véronique

    2013-01-01

    Tropical scleractinian corals are considered autotrophic as they rely mainly on photosynthesis-derived nutrients transferred from their photosymbionts. Corals are also able to capture and ingest suspended particulate organic matter, so heterotrophy can be an important supplementary trophic pathway to optimize coral fitness. The aim of this in situ study was to elucidate the trophic status of 10 coral species under contrasted environmental conditions in a French Polynesian lagoon. Carbon (?(13)C) and nitrogen (?(15)N) isotopic compositions of coral host tissues and photosymbionts were determined at 3 different fringing reefs during wet and dry seasons. Our results highlighted spatial variability in stable isotopic compositions of both coral host tissues and photosymbionts. Samples from the site with higher level of suspended particulate matter were (13)C-depleted and (15)N-enriched relative to corals and photosymbionts from less turbid sites. However, differences in both ?(13)C and ?(15)N between coral host tissues and their photosymbionts (?(host-photosymbionts 13)C and ?(host-photosymbionts 15)N) were small (0.27 ± 0.76‰ and 1.40 ± 0.90‰, respectively) and similar at all sites, thus indicating no general increases in the heterotrophic pathway. Depleted ?(13)C and enriched ?(15)N values of coral host tissues measured at the most turbid site were explained by changes in isotopic composition of the inorganic nutrients taken up by photosymbionts and also by changes in rate of isotopic fractionation with environmental conditions. Our results also highlighted a lack of significant temporal variations in ?(13)C and ?(15)N values of coral host and photosymbiont tissues and in ?(host-photosymbionts 13)C and ?(host-photosymbionts 15)N values. This temporal stability indicated that corals remained principally autotrophic even during the wet season when photosymbiont densities were lower and the concentrations of phytoplankton were higher. Increased coral heterotrophy with higher food availability thus appears to be species-specific. PMID:24312542

  2. Anatomical types of leaves and assimilating shoots and carbon 13C\\/ 12C isotope fractionation in Chinese representatives of Salsoleae s.l. (Chenopodiaceae)

    Microsoft Academic Search

    Zhibin Wen; Mingli Zhang

    2011-01-01

    To examine the anatomical types in Salsoleae s.l., and evaluate carbon isotope fractionation values for identifying the respective photosynthetic pathway, a total of 34 species representing 12 genera of Salsoleae s.l. in China were examined using light microscopy and carbon 13C\\/12C isotope fractionation. There are nine leaf anatomical types, namely, Sympegmoid (Sympegmoid type, Sympegmoid type II), Salsoloid with hypodermis (Salsola

  3. Studies of the spin-isospin response of the nuclear continuum using intermediate energy hadrons. Final technical report

    SciTech Connect

    Baker, F.T.

    1999-11-01

    The work supported by this grant has had two main thrusts. One involved study of the spin, isospin, and multipole content of the continuum of nuclei, a continuation and completion of work done at LAMPF, Saturne, and TRIUMF. Most of the work has used ({bar p}, {bar p}{prime}) or ({bar d}, {bar d}{prime}) reactions, measuring spin observable to infer properties of the target nuclei. Publications resulting from this work have included seven refereed articles and letters, five abstracts and conference talks, one of which was invited. The second thrust involved preparatory work for experiments at CEBAF. The author was involved in Hall A work and the construction, installation, and initial experiments using the proton focal plane polarimeter. Experiments began in 1997 and no referred publications have yet been completed; ten abstracts and conference talks have been published.

  4. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI

    Microsoft Academic Search

    James P. Yesinowski; Harold D. Ladouceur; Andrew P. Purdy; Joel B. Miller

    2010-01-01

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves 63Cu, 65Cu, and 127I variable temperature MAS-NMR experiments on samples of gamma-CuI, a Cu+-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical

  5. Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI

    Microsoft Academic Search

    James P. Yesinowski; Harold D. Ladouceur; Andrew P. Purdy; Joel B. Miller

    2010-01-01

    We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves 63Cu, 65Cu, and 127I variable temperature MAS-NMR experiments on samples of ?-CuI, a Cu+-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical

  6. Spin-noise correlations and spin-noise exchange driven by low-field spin-exchange collisions

    E-print Network

    A. T. Dellis; M. Loulakis; I. K. Kominis

    2014-09-28

    The physics of spin exchange collisions have fueled several discoveries in fundamental physics and numerous applications in medical imaging and nuclear magnetic resonance. We here report on the experimental observation and theoretical justification of spin-noise exchange, the transfer of spin-noise from one atomic species to another. The signature of spin-noise exchange is an increase of the total spin-noise power at low magnetic fields, on the order of 1 mG, where the two-species spin-noise resonances overlap. The underlying physical mechanism is the two-species spin-noise correlation induced by spin-exchange collisions.

  7. Nuclear

    NSDL National Science Digital Library

    Iowa Public Television. Explore More Project

    2004-01-01

    What part does nuclear energy play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to the uranium atom as an energy source. Here students read about the history of nuclear energy, how energy is derived from uranium, and benefits of nuclear energy. Information is also provided about limitations, particularly disposal problems and radioactivity, and geographical considerations of nuclear power in the United States. Thought-provoking questions afford students chances to reflect on what they've read about the uses of nuclear power. Articles and information on new nuclear plant design and nuclear accidents are available from a sidebar. Five energy-related PBS NewsHour links are provided. A web link to the U.S. Nuclear Regulatory Commission is included. Copyright 2005 Eisenhower National Clearinghouse

  8. Nuclear spins, magnetic moments, and quadrupole moments of Cu isotopes from N=28 to N=46: Probes for core polarization effects

    SciTech Connect

    Vingerhoets, P.; Avgoulea, M.; Bissell, M. L.; De Rydt, M.; Neyens, G. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, B-3001 Leuven (Belgium); Flanagan, K. T. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, B-3001 Leuven (Belgium); IPN Orsay, F-91940 Orsay Cedex (France); Billowes, J.; Cheal, B.; Mane, E. [School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Blaum, K.; Schug, M. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Brown, B. A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Forest, D. H.; Tungate, G. [School of Physics and Astronomy, The University of Birmingham, Birmingham B15 2TT (United Kingdom); Geppert, Ch.; Noertershaeuser, W. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Institut fuer Kernchemie, Johannes Gutenberg-Universitaet Mainz, D-55128 Mainz (Germany); Honma, M. [Center for Mathematical Sciences, University of Aizu, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Kowalska, M. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Kraemer, J.; Krieger, A. [Institut fuer Kernchemie, Johannes Gutenberg-Universitaet Mainz, D-55128 Mainz (Germany)

    2010-12-15

    Measurements of the ground-state nuclear spins and magnetic and quadrupole moments of the copper isotopes from {sup 61}Cu up to {sup 75}Cu are reported. The experiments were performed at the CERN online isotope mass separator (ISOLDE) facility, using the technique of collinear laser spectroscopy. The trend in the magnetic moments between the N=28 and N=50 shell closures is reasonably reproduced by large-scale shell-model calculations starting from a {sup 56}Ni core. The quadrupole moments reveal a strong polarization of the underlying Ni core when the neutron shell is opened, which is, however, strongly reduced at N=40 due to the parity change between the pf and g orbits. No enhanced core polarization is seen beyond N=40. Deviations between measured and calculated moments are attributed to the softness of the {sup 56}Ni core and weakening of the Z=28 and N=28 shell gaps.

  9. Recent developments in solid-state magic-angle spinning, nuclear magnetic resonance of fully and significantly isotopically labelled peptides and proteins.

    PubMed Central

    Straus, Suzana K

    2004-01-01

    In recent years, a large number of solid-state nuclear magnetic resonance (NMR) techniques have been developed and applied to the study of fully or significantly isotopically labelled ((13)C, (15)N or (13)C/(15)N) biomolecules. In the past few years, the first structures of (13)C/(15)N-labelled peptides, Gly-Ile and Met-Leu-Phe, and a protein, Src-homology 3 domain, were solved using magic-angle spinning NMR, without recourse to any structural information obtained from other methods. This progress has been made possible by the development of NMR experiments to assign solid-state spectra and experiments to extract distance and orientational information. Another key aspect to the success of solid-state NMR is the advances made in sample preparation. These improvements will be reviewed in this contribution. Future prospects for the application of solid-state NMR to interesting biological questions will also briefly be discussed. PMID:15306412

  10. Nuclear spins, magnetic moments and quadrupole moments of Cu isotopes from N = 28 to N = 46: probes for core polarization effects

    E-print Network

    P. Vingerhoets; K. T. Flanagan; M. Avgoulea; J. Billowes; M. L. Bissell; K. Blaum; B. A. Brown; B. Cheal; M. De Rydt; D. H. Forest; Ch. Geppert; M. Honma; M. Kowalska; J. Kramer; A. Krieger; E. Mane; R. Neugart; G. Neyens; W. Nortershauser; T. Otsuka; M. Schug; H. H. Stroke; G. Tungate; D. T. Yordanov

    2010-11-24

    Measurements of the ground-state nuclear spins, magnetic and quadrupole moments of the copper isotopes from 61Cu up to 75Cu are reported. The experiments were performed at the ISOLDE facility, using the technique of collinear laser spectroscopy. The trend in the magnetic moments between the N=28 and N=50 shell closures is reasonably reproduced by large-scale shell-model calculations starting from a 56Ni core. The quadrupole moments reveal a strong polarization of the underlying Ni core when the neutron shell is opened, which is however strongly reduced at N=40 due to the parity change between the $pf$ and $g$ orbits. No enhanced core polarization is seen beyond N=40. Deviations between measured and calculated moments are attributed to the softness of the 56Ni core and weakening of the Z=28 and N=28 shell gaps.

  11. Orientation of functional groups of soil organic matter on the surface of water repellent soils determined by pulse saturation magic angle spinning (PSTMAS) nuclear magnetic resonance (NMR) spectroscopy

    NASA Astrophysics Data System (ADS)

    Hiradate, Syuntaro; Kawamoto, Ken; Senani Wijewardana, Nadeeka; Müller, Karin; Møldrup, Per; Clothier, Brent; Komatsu, Toshiko

    2014-05-01

    Orientation of functional groups of soil organic matter on soil particles plays a crucial role in the occurrence of soil water repellency. In addition to a general method to characterize soil organic matter using cross polarization magic angle spinning (CPMAS) nuclear magnetic resonance (NMR) technique, we determined the surface orientation of functional groups in water repellent soils by using pulse saturation magic angle spinning (PSTMAS) NMR technique. A preliminary experiment confirmed that the PSTMAS NMR spectrum successfully determined the high mobility of methyl group of octadecylsilylated silica gels when a comparison was made with that of CPMAS NMR. This means that the methyl group oriented towards the outside of the silica gel particle. Similarly, for an experimental system consisting of mixtures of octadecylsilylated silica gel and dimethyl sulfoxide (DMSO), the extremely high mobility of methyl group derived from DMSO was detected using the same methodology. For water repellent soils from Japan and New Zealand, it was found that the methyl and methylene groups were highly mobile. In contrast, the NMR signals of aromatic moiety, another hydrophobic moiety of soil organic matter, were not as intense in PSTMAS compared with CPMAS. From these results, we conclude that alkyl moiety (methyl and methylene groups) would be oriented towards the outside of the soil particle and would play an important role in the appearance of water repellency of soils.

  12. Temperature-scanned magnetic resonance and the evidence of two-way transfer of a nitrogen nuclear spin hyperfine interaction in coupled NV-N pairs in diamond

    NASA Astrophysics Data System (ADS)

    Babunts, R. A.; Soltamova, A. A.; Tolmachev, D. O.; Soltamov, V. A.; Gurin, A. S.; Anisimov, A. N.; Preobrazhenskii, V. L.; Baranovi, P. G.

    2012-06-01

    New method for the detection of magnetic resonance signals versus temperature is developed on the basis of the temperature dependence of the spin Hamiltonian parameters of the paramagnetic system under investigation. The implementation of this technique is demonstrated on the nitrogen-vacancy (NV) centers in diamonds. Single NV defects and their ensembles are suggested to be almost inertialess temperature sensors. The hyperfine structure of the 14N nitrogen nuclei of the nitrogen-vacancy center appears to be resolved in the hyperfine structure characteristic of the hyperfine interaction between NV and an N s center (substitutional nitrogen impurity) in the optically detected magnetic resonance spectra of the molecular NV-N s complex. Thus, we show that a direct evidence of the two-way transfer of a nitrogen nuclear spin hyperfine interaction in coupled NV-N s pairs was observed. It is shown that more than 3-fold enhancement of the NV optically detected magnetic resonance signal can be achieved by using water as a collection optics medium.

  13. NMR multiple quantum coherences in quasi-one-dimensional spin systems: Comparison with ideal spin-chain dynamics

    E-print Network

    Zhang, Wenxian

    The [superscript 19]F spins in a crystal of fluorapatite have often been used to experimentally approximate a one-dimensional spin system. Under suitable multipulse control, the nuclear-spin dynamics may be modeled to first ...

  14. A study of the order-disorder, solid-solid phase transition of (+)-camphor using nuclear magnetic resonance with cross-polarization and magic-angle spinning

    E-print Network

    Crook, Russell Allan

    1986-01-01

    defined as the relative frequency difference between that observed for the sample and that for a suitable reference, generally tetramethylsilane ( TMS ). The value of 6 is positive for all carbon-13 nuclei which absorb at higher 6 10 (v sample... frequency than the reference. u TMS )/(uTMS ) at constant B (33) 0 w'here and v are the NMR absorption frequencies sample TMS of the sample and TMS respectively. Since shielding constants are small, the value of u in the denominator can be substituted...

  15. Leading Edge Spinning the Web of Cell Fate

    E-print Network

    Corces, Victor G.

    Leading Edge Minireview Spinning the Web of Cell Fate Kevin Van Bortle1 and Victor G. Corces1,* 1 involved in spinning the web of cell fate. Chromatin at the Nuclear Lamina The nuclear lamina is a thin

  16. Origin of cluster spin glass and nuclear Schottky anomaly in Mn50Ni38.5Sn11.5 alloy

    NASA Astrophysics Data System (ADS)

    Ray, Mayukh K.; Bagani, K.; Mukhopadhyay, P. K.; Banerjee, S.

    2015-02-01

    The magnetic ground state of the Mn50Ni38.5Sn11.5 alloy is investigated through dc/ac magnetization and low-temperature (?0.15 \\text{K}) specific-heat (Cp(T)) measurements. The dc and ac magnetization measurements indicate that the system can be identified as a cluster spin glass (CSG) phase in a ferromagnetic (FM) background, and as a conjunction of these two phases an exchange bias effect (EBE) is observed in this system. The presence of coexisting phases is further supported by our Cp(T) measurement. We attribute the existence of the CSG phase to the antiferromagnetic (AFM) interaction arising from the Mn-Mn antisite disorder which further enhances through martensite transformation. The anomalous increase of C p below 0.7 K is due to the nuclear Schottky anomaly arising from the hyperfine splitting of the nuclear levels of Mn atoms. Detailed reasons for the observed behaviours are discussed in the paper.

  17. Resonant microwave cavity for 8.512 GHz optically detected electron spin resonance with simultaneous nuclear magnetic resonance

    E-print Network

    Hart, Gus

    with simultaneous nuclear magnetic resonance J. S. Colton1,a and L. R. Wienkes2 1 Department of Physics magnetic resonance ODMR experiments. The cylindrical quasi-TE011 mode cavity is designed to fit in a 1 in. magnet bore to allow the sample to be optically accessed and to have an adjustable resonant frequency

  18. 14N nuclear quadrupole resonance and proton spin–lattice relaxation study of phase transition in pyridazine perchlorate

    Microsoft Academic Search

    J. Seliger; V. Žagar; T. Asaji

    2009-01-01

    The temperature dependence of the 14N nuclear quadrupole resonance frequencies in pyridazine perchlorate has been measured by double resonance. The results show that in the low temperature phase the pyridazinium ions are static, while in the high temperature phase the ions reorient around the normal to the plane of the ring between six equivalent orientations in agreement with the X-ray

  19. Exact analysis of polycrystalline electron spin echo envelope modulation including mutual nuclear arrangements and quadrupole interactions and its application to methyl radicals in irradiated crystals of lithium acetate dihydrate

    NASA Astrophysics Data System (ADS)

    Iwasaki, Machio; Toriyama, Kazumi

    1985-06-01

    The method of exact analysis including mutual nuclear arrangements and quadrupole interactions is developed for electron spin echo envelope modulation (ESEM) from polycrystalline samples using the formulation in an arbitrary laboratory coordinate system, which makes it possible to perform an exact angular integration. In order to assess polycrystalline ESEM by comparing with electron nuclear double resonance (ENDOR) data, the method is applied to analyze deuterium hyperfine modulation on the two-pulse electron spin echo (ESE) envelope decay observed for methyl radicals radiolytically produced in CD3COOLi ? 2H2O and CH3COOLi ? 2D2O. The results are totally consistent with our previous study by single crystal 1H ENDOR. Through this application, importance of the nuclear quadrupole term is also shown based on the exact method. The rigid deuterons in the water of crystallization show a marked quadrupole effect as compared with those in the freely rotating CD3 group. The contributions from the distant nuclei to the modulation pattern are also studied by the exact method using the crystallographic data. We have further clarified that the origin of the disagreement of a previous Li ESEM with our ENDOR is mainly in the use of a unit spin density on the spin probe despite its reduction by delocalization to the environment.

  20. Nuclear magnetic resonance studies of blends containing poly(ethylene terephthalate) (PET) and poly(p-hydroxybenzoic acid-co-p-hydroxynaphthoic acid) (Vectra-A)

    Microsoft Academic Search

    Pei Tang; Jeffrey A. Reimer; Morton M. Denn

    1993-01-01

    Solid-state NMR techniques are used to characterize the interfacial interactions and morphology in Vectra-A\\/PET blends. Two-dimensional rotor-driven [sup 13]C spin diffusion NMR and indirect detection of [sup 1]H spin-lattice relaxation (T[sub 1]) are used to determine the extent of intimate molecular mixing, carbon-13 magic angle spinning line shapes emanating from methylene carbons in PET are used to monitor the conformation

  1. Microtesla MRI with dynamic nuclear polarization

    NASA Astrophysics Data System (ADS)

    Zotev, Vadim S.; Owens, Tuba; Matlashov, Andrei N.; Savukov, Igor M.; Gomez, John J.; Espy, Michelle A.

    2010-11-01

    Magnetic resonance imaging at microtesla fields is a promising imaging method that combines the pre-polarization technique and broadband signal reception by superconducting quantum interference device (SQUID) sensors to enable in vivo MRI at microtesla-range magnetic fields similar in strength to the Earth magnetic field. Despite significant advances in recent years, the potential of microtesla MRI for biomedical imaging is limited by its insufficient signal-to-noise ratio due to a relatively low sample polarization. Dynamic nuclear polarization (DNP) is a widely used approach that allows polarization enhancement by 2-4 orders of magnitude without an increase in the polarizing field strength. In this work, the first implementation of microtesla MRI with Overhauser DNP and SQUID signal detection is described. The first measurements of carbon-13 NMR spectra at microtesla fields are also reported. The experiments were performed at the measurement field of 96 ?T, corresponding to Larmor frequency of 4 kHz for protons and 1 kHz for carbon-13. The Overhauser DNP was carried out at 3.5-5.7 mT fields using rf irradiation at 120 MHz. Objects for imaging included water phantoms and a cactus plant. Aqueous solutions of metabolically relevant sodium bicarbonate, pyruvate, alanine, and lactate, labeled with carbon-13, were used for NMR studies. All the samples were doped with TEMPO free radicals. The Overhauser DNP enabled nuclear polarization enhancement by factor as large as -95 for protons and as large as -200 for carbon-13, corresponding to thermal polarizations at 0.33 T and 1.1 T fields, respectively. These results demonstrate that SQUID-based microtesla MRI can be naturally combined with Overhauser DNP in one system, and that its signal-to-noise performance is greatly improved in this case. They also suggest that microtesla MRI can become an efficient tool for in vivo imaging of hyperpolarized carbon-13, produced by low-temperature dissolution DNP.

  2. Low Energy Nuclear Reaction Cross Sections for a Secondary High-Spin Isomeric Nuclear Beam (^18F^m) in Silicon

    Microsoft Academic Search

    D. A. Roberts; F. D. Becchetti; J. Janecke; M. Y. Lee; T. W. O'Donnell; K. Pham; R. E. Warner; R. M. Ronningen; H. W. Wilschut

    1996-01-01

    A 30 MeV\\/u primary ^17O primary beam has been used to produce a 22.3 MeV\\/u ^18F^m ( J^pi=5^+, E_x=1.1 MeV) isomeric secondary beam via the single nucleon transfer reaction ^17O(^12C,^11B)^18F. The total nuclear reaction cross section for ^18F^m , ^18F_g.s and ^16O in silicon were measured, and will be presented, in an X-Y-DeltaE-E detector telescope consisting of seven thin silicon

  3. Scalable spin amplification with a gain over a hundred.

    PubMed

    Negoro, Makoto; Tateishi, Kenichiro; Kagawa, Akinori; Kitagawa, Masahiro

    2011-07-29

    We propose a scalable and practical implementation of spin amplification which does not require individual addressing nor a specially tailored spin network. We have demonstrated a gain of 140 in a solid-state nuclear spin system of which the spin polarization has been increased to 0.12 using dynamic nuclear polarization with photoexcited triplet electron spins. Spin amplification scalable to a higher gain opens the door to the single spin measurement for a readout of quantum computers as well as practical applications of nuclear magnetic resonance spectroscopy to infinitesimal samples which have been concealed by thermal noise. PMID:21867053

  4. The gas phase ion/molecule chemistry of the carbon- 13 labeled ketenyl and methyl ketenyl anions with CS2, COS, and CO2

    NASA Astrophysics Data System (ADS)

    Robinson, Marin S.; Davico, Gustavo E.; Bierbaum, Veronica M.; Depuy, Charles H.

    1994-10-01

    A flowing afterglow-selected ion flow tube apparatus was used to study the gas phase ion/molecule chemistry of carbon-13 labeled ketenyl anions (H=C=O) with CS2, COS and CO2. In all cases, the ketenyl anion adds to the carbonyl carbon of the neutral; the resulting adduct undergoes subsequent cyclization and elimination, forming the thioketenyl anion (H=C=S) in the reactions with CS2 and COS, and a degenerate anion in the reaction with CO2 in which the C=O group of the ketenyl anion and that of CO2 are exchanged. In the reaction of the ketenyl anion with COS, both sulfur and oxygen participate in cyclization. After addition to carbon, sulfur undergoes cyclization approximately four times faster than oxygen, but all reactions eventually cyclize through oxygen before cleavage to product. An unexpectedly small reaction efficiency was observed in the reaction of the ketenyl anion with CS2. To explain this finding, we propose that energy randomization in the initially formed adduct is slow, thereby increasing the probability of decomposition. The reactions of carbon-13 labeled methyl ketenyl anions (CH3=C=O) with CS2, COS, and CO2 were also studied and produce analogous results.

  5. Increasing Quantum Dot Electron Spin Coherence with Persistent Spin Narrowing

    Microsoft Academic Search

    Bo Sun; Colin Chow; Allan Bracker; Daniel Gammon; Lu Sham; Duncan Steel

    2011-01-01

    We demonstrate reproducible initialization of the Overhauser field in a single InAs self-assembled quantum dot using the hole assisted nuclear feedback mechanism. This fixes the mean the Overhauser field to a value determined by two pump lasers and dramatically reduces the statistical broadening of the electron spin resonance arising from averaging over the nuclear spin ensemble, (1\\/T2*). By initializing for

  6. Nuclear Spin Lattice Relaxation and Conductivity Studies of the Non-Arrhenius Conductivity Behavior in Lithium Fast Ion Conducting Sulfide Glasses

    SciTech Connect

    Benjamin Michael Meyer

    2003-05-31

    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 of ethanol in gasoline. Consumers are increasingly demanding that energy sources be more powerful, more durable, and, ultimately, more cost efficient. Fast Ionic Conducting (FIC) glasses are a material that offers great potential for the development of new batteries and/or fuel cells to help inspire the energy density of battery power supplies. This dissertation probes the mechanisms by which ions conduct in these glasses. A variety of different experimental techniques give a better understanding of the interesting materials science taking place within these systems. This dissertation discusses Nuclear Magnetic Resonance (NMR) techniques performed on FIC glasses over the past few years. These NMR results have been complimented with other measurement techniques, primarily impedance spectroscopy, to develop models that describe the mechanisms by which ionic conduction takes place and the dependence of the ion dynamics on the local structure of the glass. The aim of these measurements was to probe the cause of a non-Arrhenius behavior of the conductivity which has been seen at high temperatures in the silver thio-borosilicate glasses. One aspect that will be addressed is if this behavior is unique to silver containing fast ion conducting glasses. more specifically, this study will determine if a non-Arrhenius correlation time, {tau}, can be observed in the Nuclear Spin Lattice Relaxation (NSLR) measurements. If so, then can this behavior be modeled with a new single distribution of activation energies (DAE) to calculate the corresponding conductivity and relaxation rates as a function of temperature and frequency?

  7. BLACK HOLE-NEUTRON STAR MERGERS WITH A HOT NUCLEAR EQUATION OF STATE: OUTFLOW AND NEUTRINO-COOLED DISK FOR A LOW-MASS, HIGH-SPIN CASE

    SciTech Connect

    Deaton, M. Brett; Duez, Matthew D. [Department of Physics and Astronomy, Washington State University, Pullman, WA 99164 (United States); Foucart, Francois; O'Connor, Evan [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario M5S 3H8 (Canada); Ott, Christian D.; Scheel, Mark A.; Szilagyi, Bela [TAPIR, MC 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Kidder, Lawrence E.; Muhlberger, Curran D., E-mail: mbdeaton@wsu.edu, E-mail: m.duez@wsu.edu [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)

    2013-10-10

    Neutrino emission significantly affects the evolution of the accretion tori formed in black hole-neutron star mergers. It removes energy from the disk, alters its composition, and provides a potential power source for a gamma-ray burst. To study these effects, simulations in general relativity with a hot microphysical equation of state (EOS) and neutrino feedback are needed. We present the first such simulation, using a neutrino leakage scheme for cooling to capture the most essential effects and considering a moderate mass (1.4 M{sub ?} neutron star, 5.6 M{sub ?} black hole), high-spin (black hole J/M {sup 2} = 0.9) system with the K{sub 0} = 220 MeV Lattimer-Swesty EOS. We find that about 0.08 M{sub ?} of nuclear matter is ejected from the system, while another 0.3 M{sub ?} forms a hot, compact accretion disk. The primary effects of the escaping neutrinos are (1) to make the disk much denser and more compact, (2) to cause the average electron fraction Y{sub e} of the disk to rise to about 0.2 and then gradually decrease again, and (3) to gradually cool the disk. The disk is initially hot (T ? 6 MeV) and luminous in neutrinos (L{sub ?} ? 10{sup 54} erg s{sup –1}), but the neutrino luminosity decreases by an order of magnitude over 50 ms of post-merger evolution.

  8. Taurine detected using high-resolution magic angle spinning (1)H nuclear magnetic resonance: A potential indicator of early myocardial infarction.

    PubMed

    Yang, Yunlong; Yang, Lin; Zhang, Yue; Gu, Xinghua; Xu, Danling; Fang, Fang; Sun, Aijun; Wang, Keqiang; Yu, Yihua; Zuo, Ji; Ge, Junbo

    2013-03-01

    Magnetic resonance spectroscopy (MRS) is a unique non-invasive method for detecting cardiac metabolic changes. However, MRS in cardiac diagnosis is limited due to insensitivity and low efficiency. Taurine (Tau) is the most abundant free amino acid in the myocardium. We hypothesized that Tau levels may indicate myocardial ischemia and early infarction. Sprague-Dawley rats were divided into seven groups according to different time points during the course of myocardial ischemia, which was induced by left anterior descending coronary artery ligation. Infarcted myocardial tissue was obtained for high-resolution magic angle spinning (1)H nuclear magnetic resonance (NMR) analysis. Results were validated via high-performance liquid chromatography. The Tau levels in the ischemic myocardial tissue were reduced significantly within 5 min compared with those in the control group (relative ratio from 20.27±6.48 to 8.81±0.04, P<0.05) and were maintained for 6 h post-ischemia. Tau levels declined more markedly (56.5%) than creatine levels (48.5%) at 5 min after ligation. This suggests that Tau may have potential as an indicator in the early detection of myocardial ischemia by (1)H MRS. PMID:23408155

  9. Taurine detected using high-resolution magic angle spinning 1H nuclear magnetic resonance: A potential indicator of early myocardial infarction

    PubMed Central

    YANG, YUNLONG; YANG, LIN; ZHANG, YUE; GU, XINGHUA; XU, DANLING; FANG, FANG; SUN, AIJUN; WANG, KEQIANG; YU, YIHUA; ZUO, JI; GE, JUNBO

    2013-01-01

    Magnetic resonance spectroscopy (MRS) is a unique non-invasive method for detecting cardiac metabolic changes. However, MRS in cardiac diagnosis is limited due to insensitivity and low efficiency. Taurine (Tau) is the most abundant free amino acid in the myocardium. We hypothesized that Tau levels may indicate myocardial ischemia and early infarction. Sprague-Dawley rats were divided into seven groups according to different time points during the course of myocardial ischemia, which was induced by left anterior descending coronary artery ligation. Infarcted myocardial tissue was obtained for high-resolution magic angle spinning 1H nuclear magnetic resonance (NMR) analysis. Results were validated via high-performance liquid chromatography. The Tau levels in the ischemic myocardial tissue were reduced significantly within 5 min compared with those in the control group (relative ratio from 20.27±6.48 to 8.81±0.04, P<0.05) and were maintained for 6 h post-ischemia. Tau levels declined more markedly (56.5%) than creatine levels (48.5%) at 5 min after ligation. This suggests that Tau may have potential as an indicator in the early detection of myocardial ischemia by 1H MRS. PMID:23408155

  10. Investigation of humic acid N with X-ray photoelectron spectroscopy: Effect of acid hydrolysis and comparison with 15N cross polarization\\/magic angle spinning nuclear magnetic resonance spectroscopy

    Microsoft Academic Search

    Tomonori Abe; Nagamitu Maie; Akira Watanabe

    2005-01-01

    Nitrogen in humic substances has an important function as a reservoir of plant nutrient. To elucidate the stability of humic acid N in soil with respect to chemical structure, X-ray photoelectron spectroscopy (XPS) and 15N cross polarization\\/magic angle spinning nuclear magnetic resonance (CPMAS NMR) spectroscopy were applied to humic acids with various degrees of humification. The composition of the non-hydrolyzable

  11. Effects of Clay Fraction and Temperature on the H2O Self-Diffusivity in Hectorite Gel: A Pulsed-Field-Gradient Spin-Echo Nuclear Magnetic Resonance Study

    Microsoft Academic Search

    Yoshito Nakashima

    2000-01-01

    Self-diffusion coefficients of H20 molecules in Na-rich hectorite gel were measured by IH nuclear magnetic resonance (NMR). Spin-echo pulse sequences with magnetic field gradient pulses for the translational diffusion measurement were applied to the hectorite gel at the Larmor frequency of 20 MHz. Effects of clay fraction (0-51.2 wt. %) and temperature (20.0-60.3~ were studied. The results show: (1) Phenomenologically,

  12. Geometrical spin symmetry and spin

    SciTech Connect

    Pestov, I. B., E-mail: pestov@theor.jinr.ru [Joint Institute for Nuclear Research (Russian Federation)

    2011-07-15

    Unification of General Theory of Relativity and Quantum Mechanics leads to General Quantum Mechanics which includes into itself spindynamics as a theory of spin phenomena. The key concepts of spindynamics are geometrical spin symmetry and the spin field (space of defining representation of spin symmetry). The essence of spin is the bipolar structure of geometrical spin symmetry induced by the gravitational potential. The bipolar structure provides a natural derivation of the equations of spindynamics. Spindynamics involves all phenomena connected with spin and provides new understanding of the strong interaction.

  13. THz Dynamic Nuclear Polarization NMR

    E-print Network

    Nanni, Emilio Alessandro

    Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The ...

  14. On Spin Fluctuations in Dense Matter and Skyrme Interactions

    SciTech Connect

    Sagawa, H.; Margueron, J. [Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, 965-8580 Fukushima (Japan)

    2009-05-07

    A modification of the standard Skyrme interaction is proposed so that the spin and spin-isospin instability is removed. The new terms are density dependent and modify only the spin p-h interaction in the case of spin-saturated system. The Landau parameters are examined to improve spin and spin-isospin properties of Skyrme interactions in finite nuclei and nuclear matter.

  15. Spinning angle optical calibration apparatus

    DOEpatents

    Beer, Stephen K. (Morgantown, WV); Pratt, II, Harold R. (Morgantown, WV)

    1991-01-01

    An optical calibration apparatus is provided for calibrating and reproducing spinning angles in cross-polarization, nuclear magnetic resonance spectroscopy. An illuminated magnifying apparatus enables optical setting an accurate reproducing of spinning "magic angles" in cross-polarization, nuclear magnetic resonance spectroscopy experiments. A reference mark scribed on an edge of a spinning angle test sample holder is illuminated by a light source and viewed through a magnifying scope. When the "magic angle" of a sample material used as a standard is attained by varying the angular position of the sample holder, the coordinate position of the reference mark relative to a graduation or graduations on a reticle in the magnifying scope is noted. Thereafter, the spinning "magic angle" of a test material having similar nuclear properties to the standard is attained by returning the sample holder back to the originally noted coordinate position.

  16. Spin caloritronics.

    PubMed

    Bauer, Gerrit E W; Saitoh, Eiji; van Wees, Bart J

    2012-05-01

    Spintronics is about the coupled electron spin and charge transport in condensed-matter structures and devices. The recently invigorated field of spin caloritronics focuses on the interaction of spins with heat currents, motivated by newly discovered physical effects and strategies to improve existing thermoelectric devices. Here we give an overview of our understanding and the experimental state-of-the-art concerning the coupling of spin, charge and heat currents in magnetic thin films and nanostructures. Known phenomena are classified either as independent electron (such as spin-dependent Seebeck) effects in metals that can be understood by a model of two parallel spin-transport channels with different thermoelectric properties, or as collective (such as spin Seebeck) effects, caused by spin waves, that also exist in insulating ferromagnets. The search to find applications--for example heat sensors and waste heat recyclers--is on. PMID:22522639

  17. Spectroscopy of composite solid-state spin environments for improved metrology with spin ensembles

    NASA Astrophysics Data System (ADS)

    Bar-Gill, Nir; Pham, Linh; Belthangady, Chinmay; Lesage, David; Cappellaro, Paola; Maze, Jeronimo; Lukin, Mikhail; Yacoby, Amir; Walsworth, Ronald

    2012-02-01

    For precision coherent measurements with ensembles of quantum spins the relevant Figure-of-Merit (FOM) is the product of spin density and coherence lifetime, which is generally limited by the dynamics of spin coupling to the environment. Significant effort has been invested in understanding the causes of decoherence in a diverse range of spin systems in order to increase the FOM and improve measurement sensitivity. Here, we apply a coherent spectroscopic technique to characterize the dynamics of a composite solid-state spin environment consisting of Nitrogen-Vacancy (NV) color centers in room temperature diamond coupled to baths of electronic spin (N) and nuclear spin (13C) impurities. For diamond samples with a wide range of NV densities and impurity spin concentrations we employ a dynamical decoupling technique to minimize coupling to the environment, and find similar values for the FOM, which is three orders of magnitude larger than previously achieved in any room-temperature solid-state spin system, and thus should enable greatly improved precision spin metrology. We also identify a suppression of electronic spin bath dynamics in the presence of a nuclear spin bath of sufficient nuclear spin concentration. This suppression could inform efforts to engineer samples with even larger FOM for solid-state spin ensemble metrology and collective quantum information processing.

  18. Analysis of metabolic characteristics in a rat model of chronic pancreatitis using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy

    PubMed Central

    TIAN, BING; MA, CHAO; WANG, JIAN; PAN, CHUN-SHU; YANG, GEN-JIN; LU, JIAN-PING

    2015-01-01

    Pathological and metabolic alterations co-exist and co-develop in the progression of chronic pancreatitis (CP). The aim of the present study was to investigate the metabolic characteristics and disease severity of a rat model of CP in order to determine associations in the observed pathology and the metabolites of CP using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR). Wistar rats (n=36) were randomly assigned into 6 groups (n=6 per group). CP was established by administering dibutyltin dichloride solution into the tail vein. After 0, 7, 14, 21, 28 and 35 days, the pancreatic tissues were collected for pathological scoring or for HR-MAS NMR. Correlation analyses between the major pathological scores and the integral areas of the major metabolites were determined. The most representative metabolites, aspartate, betaine and fatty acids, were identified as possessing the greatest discriminatory significance. The Spearman’s rank correlation coefficients between the pathology and metabolites of the pancreatic tissues were as follows: Betaine and fibrosis, 0.454 (P=0.044); betaine and inflammatory cell infiltration, 0.716 (P=0.0001); aspartate and fibrosis, ?0.768 (P=0.0001); aspartate and inflammatory cell infiltration, ?0.394 (P=0.085); fatty acid and fibrosis, ?0.764 (P=0.0001); and fatty acid and inflammatory cell infiltration, ?0.619 (P=0.004). The metabolite betaine positively correlated with fibrosis and inflammatory cell infiltration in CP. In addition, aspartate negatively correlated with fibrosis, but exhibited no significant correlation with inflammatory cell infiltration. Furthermore, the presence of fatty acids negatively correlated with fibrosis and inflammatory cell infiltration in CP. HR-MAS NMR may be used to analyze metabolic characteristics in a rat model of different degrees of chronic pancreatitis. PMID:25338744

  19. Magic angle spinning nuclear magnetic resonance characterization of voltage-dependent anion channel gating in two-dimensional lipid crystalline bilayers.

    PubMed

    Eddy, Matthew T; Andreas, Loren; Teijido, Oscar; Su, Yongchao; Clark, Lindsay; Noskov, Sergei Y; Wagner, Gerhard; Rostovtseva, Tatiana K; Griffin, Robert G

    2015-02-01

    The N-terminus of the voltage-dependent anion channel (VDAC) has been proposed to contain the mechanistically important gating helices that modulate channel opening and closing. In this study, we utilize magic angle spinning nuclear magnetic resonance (MAS NMR) to determine the location and structure of the N-terminus for functional channels in lipid bilayers by measuring long-range (13)C-(13)C distances between residues in the N-terminus and other domains of VDAC reconstituted into DMPC lipid bilayers. Our structural studies show that the distance between A14 C? in the N-terminal helix and S193 C? is ?4-6 Å. Furthermore, VDAC phosphorylation by a mitochondrial kinase at residue S193 has been claimed to delay mitochondrial cell death by causing a conformational change that closes the channel, and a VDAC-Ser193Glu mutant has been reported to show properties very similar to those of phosphorylated VDAC in a cellular context. We expressed VDAC-S193E and reconstituted it into DMPC lipid bilayers. Two-dimensional (13)C-(13)C correlation experiments showed chemical shift perturbations for residues located in the N-terminus, indicating possible structural perturbations to that region. However, electrophysiological data recorded on VDAC-S193E showed that channel characteristics were identical to those of wild type samples, indicating that phosphorylation of S193 does not directly affect channel gating. The combination of NMR and electrophysiological results allows us to discuss the validity of proposed gating models. PMID:25545271

  20. Initialization and readout of spin chains for quantum information transport

    Microsoft Academic Search

    Gurneet Kaur; Paola Cappellaro

    2012-01-01

    Linear chains of spins acting as quantum wires are a promising approach for achieving scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test bed for the experimental study of quantum information transport, as they closely emulate a one-dimensional spin chain, while magnetic resonance techniques can be used to drive the spin chain dynamics and probe the

  1. Nuclear Magnetic Resonance Spectroscopy. 13C Fourier Transform Spectra of ?8- and ?9-Tetrahydrocannabinol

    PubMed Central

    Hawkins, Bruce L.; Roberts, John D.

    1973-01-01

    Carbon-13 nuclear magnetic resonance spectra have been taken of ?8- and ?9-tetrahydrocannabinol. The absorptions have been assigned to specific carbons with the aid of off-resonance and selective proton-decoupling experiments, as well as by chemical-shift comparison with model compounds. PMID:4515603

  2. Vibrational properties of the polymeric spin crossover (SCO) Fe(II) complexes [{Fe(4-amino-1,2,4-triazole)3}X2]n: a nuclear inelastic scattering (NIS), Raman and DFT study.

    PubMed

    Rackwitz, Sergej; Wolny, Juliusz A; Muffler, Kai; Achterhold, Klaus; Rüffer, Rudolf; Garcia, Yann; Diller, Rolf; Schünemann, Volker

    2012-11-14

    The vibrational properties of the cationic spin crossover (SCO) coordination polymers [{Fe(4-amino-1,2,4-triazole)(3)}(+2)](n) containing the anions chlorine, methanosulfonate and 1-naphthalenesulfonate have been studied via nuclear inelastic scattering of synchrotron radiation (NIS) as well as by Raman spectroscopy. Although the different anions have a strong influence on the spin crossover temperature, they have little effect on the positions of the spin marker bands in the NIS and Raman spectra. By comparing the line positions of the NIS spin marker bands with those observed by Raman spectroscopy, it has been possible to distinguish vibrations symmetry (A(u) or A(g)) because modes of A(u) and A(g) symmetries are NIS active, but only the A(g) modes are Raman active. The normal mode analysis of charge compensated cationic pentameric and hexameric model structures which have been obtained by density functional calculations reproduces the experimentally observed mode frequencies and the geometry optimization reproduces iron-ligand distances reported for these and related SCO coordination complexes. The effect of charge compensation appears to be independent of the choice of the functional and the basis set which shows that DFT calculations using B3LYP in conjunction with the basis set CEP-31G are a time effective approach in order to study vibrational properties of Fe(II) SCO compounds. PMID:23032912

  3. Proton and deuterium nuclear spin relaxation study of the SmA and SmC* phases of BP8Cl-d17 : a self-consistent analysis.

    PubMed

    Ferraz, A; Zhang, J; Sebastião, P J; Ribeiro, A C; Dong, Ronald Y

    2014-10-01

    A self-consistent analysis of proton and deuterium nuclear spin relaxation times in the smectic phases of a partially deuterated smectogen is presented here. Proton spin-lattice relaxation times T(1Z) were measured as a function of Larmor frequency over a range of 1?kHz to 300?MHz at selected temperatures. Deuterium spin relaxation times T(1Z) and T(1Q) were measured as a function of temperature at two different magnetic fields in the smectic A phase. The deuterium data provide dynamic parameters such as rotational diffusion constants and internal jump rates as well as the nematic order parameter S. The proton data are analyzed using a number of relaxation mechanisms, one of which is the molecular reorientation. It is found helpful in these latter analyses to use the nematic order parameter and to fix the contribution from molecular reorientations determined by the deuterium spin relaxation. The fits to the proton T(1) frequency and temperature dispersions by the remaining relaxation mechanisms such as layer undulations and translational self-diffusion will be discussed for the smectic A and chiral smectic C phases. PMID:25132369

  4. Kinetics of alpha-mannosidase action on various alpha-D-mannopyranosyl linkages in hen ovalbumin glycopeptides as monitored by carbon 13 nuclear magnetic resonance spectroscopy.

    PubMed

    Berman, E; Allerhand, A

    1981-07-10

    We show that 13C NMR spectroscopy is a practical method for following the kinetics of enzymatic digestion of individual carbohydrate residues of glycopeptides and for determining the structures of the products of partial digestions. Specifically, we study the jack bean alpha-mannosidase digestion of the two hen ovalbumin glycopeptides Man alpha 1 leads to 6(Man alpha 1 leads to 3)Man alpha 1 leads to 6(Man alpha 1 leads to 2Man alpha 1 leads to 3)Man beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc beta 1 leads to Asn (Compound A) and Man alpha 1 leads to 6(Man alpha 1 leads to 3)Man alpha 1 leads to 6(Man alpha 1 leads to 3)Man beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc beta 1 leads to Asn (Compound B). The reported "rule" that jack bean alpha-mannosidase hydrolyzes Man alpha 1 leads to 2Man and Man alpha 1 leads to 6Man linkages at least 15 times faster than Man alpha 1 leads to 3Man linkages (Tai, T., Yamashita, K., Ogata-Arakawa, M., Koide, N., Muramatsu, T., Iwashita, S., Inoue, Y., and Kobata, A. (1975) J. Biol. Chem. 250, 8569-8575) is not of general validity. Although the Man alpha 1 leads to 2Man (alpha) linkage of Compound A is the first one to be digested, the Man alpha 1 leads to 3Man (beta) linkage is hydrolyzed next, faster than the Man alpha 1 leads to 6Man (alpha) linkage. The Man alpha 1 leads to 3Man (alpha) linkage is hydrolyzed very slowly. We show that it is practical to use 13C NMR spectroscopy to determine when the enzymatic digestion should be halted to isolate derivatives such as Man alpha 1 leads to 6(Man alpha 1 leads to 3)Man alpha 1 leads to 6Man beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc beta 1 leads to Asn and Man alpha 1 leads to 3Man alpha 1 leads to 6Man beta 1 leads to 4GlcNAc beta 1 leads to 4GlcNAc beta 1 leads to Asn. PMID:7240235

  5. Determination of the position of the N-O function in substituted pyrazine N-oxides by chemometric analysis of carbon-13 nuclear magnetic resonance data

    NASA Astrophysics Data System (ADS)

    Butler, Matias; Cabrera, Gabriela M.

    2013-07-01

    Investigations were carried out applying NMR spectroscopy for the unambiguous determination of the position of the N-oxide function in a set of 2-substituted pyrazine N-oxides synthesized in our group. Applying chemometric techniques of multivariate analysis to the 13C NMR chemical shifts data set, useful relationships for identifying the position of the N-oxide group relative to the substituent were unraveled. The relationships obtained were rationalized in terms of the molecular structures and refined. As a result, an index of N-oxidation (INOx) was defined, computed simply contrasting the average 13C NMR chemical shifts of each pair of carbon atoms bonded to a nitrogen atom. The effect of the substituent was included through a factor x (subscript of INO) close to unity, multiplying the average containing the substituted carbon atom. The approach was successful in recognizing the position of the N-oxide in all the cases studied, as revealed by the sign of INOx (positive for 1-N-oxides and negative for 4-N-oxides). The scope of the methodology was further tested using the 13C NMR chemical shifts of disubstituted pyrazine N-oxides from the literature data.

  6. High-spin properties from energy-energy correlation studies using the spin spectrometer

    SciTech Connect

    Lee, I.Y.

    1982-01-01

    The continuum ..gamma.. rays from /sup 130/Ce were studied using the spin spectrometer. One-dimensional and two-dimensional spectra were analyzed as a function of angle, spin and entry energy. Spin and temperature dependence of nuclear properties were observed.

  7. Nuclear collective dynamics

    Microsoft Academic Search

    D. Bucurescu; V. Ceausescu; N. V. Zamfir

    1983-01-01

    Topics discussed in this International Summer School of Nuclear Physics include time dependent and Hartree-Fock methods in quantum mechanics and nuclear models; angular momentum, high spin states, giant resonance, nuclear deformation, collective model and excitations; nuclear molecules; heavy ion reactions; fission reactions; and inertial confinement.

  8. Quantitative Determination of Chemical Processes by Dynamic Nuclear Polarization Enhanced Nuclear Magnetic Resonance Spectroscopy

    E-print Network

    Zeng, Haifeng

    2012-07-16

    Dissolution dynamic nuclear polarization (DNP) provides several orders of magnitude of NMR signal enhancement by converting the much larger electron spin polarization to nuclear spin polarization. Polarization occurs at low temperature (1.4K...

  9. Carbon-13 NMR studies of salt shock-induced carbohydrate turnover in the marine cyanobacterium Agmenellum quadruplicatum

    NASA Technical Reports Server (NTRS)

    Tel-Or, E.; Spath, S.; Packer, L.; Mehlhorn, R. J.

    1986-01-01

    Carbon turnover in response to abrupt changes in salinity, including the mobilization of glycogen for use in osmoregulation was studied with pulse-chase strategies utilizing nuclear magnetic resonance (NMR)-silent and NMR-detectable 12C and 13C isotopes, respectively. Growth of Agmenellum quadruplicatum in 30%-enriched 13C bicarbonate provided sufficient NMR-detectability of intracellular organic osmoregulants for these studies. A comparison of NMR spectra of intact cells and their ethanol extracts showed that the intact cell data were suitable for quantitative work, and, when combined with ESR measurements of cell volumes, yielded intracellular glucosylglycerol concentrations without disrupting the cells. NMR pulse-chase experiments were used to show that 13C-enriched glycogen, which had previously been accumulated by the cells under nitrogen-limited growth at low salinities, could be utilized for the synthesis of glucosylglycerol when the cells were abruptly transferred to hypersaline media, but only in the light. It was also shown that the accumulation of glucosylglycerol in the light occurred on a time scale similar to that of cell doubling. Depletion of glucosylglycerol when cells abruptly transferred to lower salinities appeared to be rapid--the intracellular pool of this osmoregulant was decreased 2-fold within 2 hours of hypotonic shock.

  10. Initialization and readout of spin chains for quantum information transport

    E-print Network

    Kaur, Gurneet

    Linear chains of spins acting as quantum wires are a promising approach for achieving scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test bed for the experimental study of quantum ...

  11. 1-Cyclohepta-2,4,6-trienyl-selanes--a 77Se NMR study: indirect nuclear 77Se--13C spin-spin coupling constants and application of density functional theory (DFT) calculations.

    PubMed

    Wrackmeyer, Bernd; Hernández, Zureima García; Herberhold, Max

    2007-03-01

    1-Cyclohepta-2,4,6-trienyl-selanes Se(C(7)H(7))(2) (2c), R--Se--C(7)H(7) with R = Bu, (t)Bu, Ph, 4-F--C(6)H(4) (12a,b,c,d) were prepared by the reaction of the corresponding silanes, Si(SeMe(3))(2) and R--Se--SiMe(3), respectively, with tropylium bromide C(7)H(7)Br. In spite of the low stability of the selanes even in dilute solutions and at low temperature, they could be characterised by their (1)H, (13)C and (77)Se NMR parameters. Coupling constants (1)J((77)Se,(13)C) were measured and calculated by DFT methods at the B3LYP/6-311+G(d,p) level of theory. The comparison of experimental and calculated coupling constants (1)J((77)Se,(13)C) included numerous selenium carbon compounds with largely different Se--C bonds, revealing a satisfactory agreement. Both the spin-dipole (SD) and the paramagnetic spin-orbital (PSO) terms contributed significantly to the spin-spin coupling interaction, in addition to the Fermi contact (FC) term. PMID:17183533

  12. Transfer of spin angular momentum from Cs vapor to nearby Cs salts through laser-induced spin currents

    SciTech Connect

    Ishikawa, K.; Patton, B.; Olsen, B. A.; Jau, Y.-Y.; Happer, W. [Graduate School of Material Science, University of Hyogo, Ako-gun, Hyogo 678-1297 (Japan); Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

    2011-06-15

    Optical pumping of alkali-metal atoms in vapor cells causes spin currents to flow to the cell walls where excess angular momentum accumulates in the wall nuclei. Experiments reported here indicate that the substantial enhancement of the nuclear-spin polarization of salts at the cell walls is primarily due to the nuclear-spin current, with a lesser contribution from the electron-spin current of the vapor.

  13. Estimating groundwater mixing and origin in an overexploited aquifer in Guanajuato, Mexico, using stable isotopes (strontium-87, carbon-13, deuterium and oxygen-18).

    PubMed

    Horst, Axel; Mahlknecht, Jürgen; Merkel, Broder J

    2007-12-01

    Stable Isotopes (strontium-87, deuterium and oxygen-18, carbon-13) have been used to reveal different sources of groundwater and mixing processes in the aquifer of the Silao-Romita Valley in the state of Guanajuato, Mexico. Calcite dissolution appeared to be the main process of strontium release leading to relatively equal (87)Sr/(86)Sr ratios of 0.7042-0.7062 throughout the study area which could be confirmed by samples of carbonate rocks having similar Sr ratios (0.7041-0.7073). delta(13)C values (-11.91- -6.87 per thousand VPDB) of groundwaters confirmed the solution of carbonates but indicated furthermore influences of soil-CO(2). Deuterium and (18)O contents showed a relatively narrow range of-80.1- -70.0 per thousand VSMOW and -10.2- -8.8 per thousand, VSMOW, respectively but are affected by evaporation and mixing processes. The use of delta(13)C together with (87)Sr/(86)Sr revealed three possible sources: (i) carbonate-controlled waters showing generally higher Sr-concentrations, (ii) fissure waters with low-strontium contents and (iii) infiltrating water which is characterized by low delta(13)C and (87)Sr/(86)Sr ratios. The third component is affected by evaporation processes taking place before and during infiltration which might be increased by extraction and reinfiltration (irrigation return flow). PMID:18041622

  14. Gordon Conference on Nuclear Research

    SciTech Connect

    Austin, S.M.

    1983-09-01

    Session topics were: quarks and nuclear physics; anomalons and anti-protons; the independent particle structure of nuclei; relativistic descriptions of nuclear structure and scattering; nuclear structure at high excitation; advances in nuclear astrophysics; properties of nuclear material; the earliest moments of the universe; and pions and spin excitations in nuclei.

  15. Protecting a Solid-State Spin from Decoherence Using Dressed Spin States

    NASA Astrophysics Data System (ADS)

    Golter, D. Andrew; Baldwin, Thomas K.; Wang, Hailin

    2014-12-01

    We report experimental studies of dressing an electron spin in diamond with resonant and continuous microwave fields to protect the electron spin from magnetic fluctuations induced by the nuclear spin bath. We use optical coherent population trapping (CPT) to probe the energy level structure, optically induced spin transitions, and spin decoherence rates of the dressed spin states. Dressing an electron spin with resonant microwaves at a coupling rate near 1 MHz leads to a 50 times reduction in the linewidth of the spin transition underlying the CPT process, limited by transit-time broadening. Compared with dynamical decoupling, where effects of the bath are averaged out at specific times, the dressed spin state provides a continuous protection from decoherence.

  16. Constraints on anomalous spin-spin interactions from spin-exchange collisions

    NASA Astrophysics Data System (ADS)

    Jackson Kimball, D. F.; Boyd, Alec; Budker, D.

    2010-12-01

    A comparison between existing measurements and calculated cross sections for spin exchange between alkali-metal atoms and noble gases (specifically sodium and helium) is used to constrain anomalous spin-dependent forces between nuclei at the atomic scale (~10-8 cm). Combined with existing stringent limits on anomalous short-range, spin-dependent couplings of the proton, the dimensionless coupling constant for an axial vector interaction of the neutron arising from exchange of a boson of mass ?100 eV is constrained to be gAn/4??c<2×10-3. Constraints are established for a velocity- and spin-dependent interaction ?(I·v)(K·v), where I and K are the nuclear spins of He and Na, respectively, and v is the relative velocity of the atoms. Constraints on torsion gravity are also considered.

  17. Quantum spin coherence in halogen-modified Cr$_7$Ni molecular nanomagnets

    E-print Network

    Danielle Kaminski; Amy L. Webber; Christopher J. Wedge; Junjie Liu; Grigore A. Timco; Inigo J. Vitorica-Yrezabal; Eric J. L. McInnes; Richard E. P. Winpenny; Arzhang Ardavan

    2014-10-30

    Among the factors determining the quantum coherence of the spin in molecular magnets is the presence and the nature of nuclear spins in the molecule. We have explored modifying the nuclear spin environment in Cr$_7$Ni-based molecular nanomagnets by replacing hydrogen atoms with deuterium or the halogen atoms, fluorine or chlorine. We find that the spin coherence, studied at low temperatures by pulsed electron spin resonance, is modified by a range of factors, including nuclear spin and magnetic moment, changes in dynamics owing to nuclear mass, and molecular morphology changes.

  18. Carbon-13 variation in limestone on an aquifer-wide scale and its effect on ground-water radiocarbon dating models

    SciTech Connect

    Mayo, A.L.

    1985-01-01

    A number of ground-water radiocarbon dating models exist. Sensitivity analysis has shown that with certain plausible combinations of input data, the model results are appreciably dependent on the 13-C content of the mineral carbon reservoir used. It is common practice to fix this value, in many cases based on a single analysis or an estimate. This study examines the natural variations observed in the parameter on a variety of scales. Carbon-13 variations in the Mooney Falls Member of the Redwall Limestone were studied. Nine sampling sites were selected, ranging from 6 kilometers to one hundred kilometers apart. Two samples were taken from each site, one from about 1 meter and one from about 6 meters above the base. Results show differences in 13-C as great as 4 per thousand delta/sup 13/C vs PDB of the fracture surfaces and bulk rock. This is important since the infiltrating ground water interacts with these surfaces while the 13-C contents of the bulk rock is generally used in the models. This may lead to differences of several hundred to some thousand years in the estimated age of the waters. The general conclusions from this study are that: 1) there are conditions in ground-water dating under which it is misleading to assume that natural 13-C variations in the mineral carbon reservoir are negligible, and 2) there are conditions under which it is important to assure that the 13-C value used in modeling represents the composition of the material with which the water interacts rather than the bulk rock.

  19. Spin and spin-isospin instabilities and Landau parameters of Skyrme interactions with tensor correlations

    SciTech Connect

    Cao Ligang [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000 (China); Dipartimento di Fisica, Universita degli Studi di Milano, via Celoria 16, Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, Milano (Italy); Colo, Gianluca [Dipartimento di Fisica, Universita degli Studi di Milano, via Celoria 16, Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, Milano (Italy); Sagawa, Hiroyuki [Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8560 (Japan)

    2010-04-15

    The Landau parameters of Skyrme interactions in the spin and spin-isospin channels are studied using various Skyrme effective interactions with and without tensor correlations. We focus on the role of the tensor terms on the spin and spin-isospin instabilities that can occur in nuclear matter above saturation density. We point out that these instabilities are realized in nuclear matter at the critical density of about two times the saturation density for all the adopted parameter sets. The critical density is shown to be very much dependent not only on the choice of the Skyrme parameter set, but also on the inclusion of the tensor terms.

  20. Population and decay of high-spin states in ¹⁵⁷⁻¹⁶¹Yb: evolution of nuclear shapes as a function spin and neutron number

    Microsoft Academic Search

    M. Jaeaeskelaeinen; D. G. Sarantites; F. A. Dilmanian; R. Woodward; H. Puchta; J. R. Beene; M. L. Halbert; J. Hattula; D. C. Hensley; J. H. Barker

    1982-01-01

    The population and decay of the entry states in ¹⁵⁷⁻¹⁶¹Yb and ¹⁵⁵⁻¹⁵⁸Er from the reactions of 136- and 149-MeV ²°Ne with ¹⁴⁴Nd and ¹⁴⁶Nd have been investigated with the Spin Spectrometer gated with a Ge detector. Statistical-model calculations reproduce the main features of the entry state populations. The entry lines, as a function of multiplicity, M\\/sub ..gamma..\\/ show

  1. Population and decay of high-spin states in ¹⁵⁷⁻sup 161\\/Yb: evolution of nuclear shapes as a function of spin and neutron number

    Microsoft Academic Search

    M. Jaeaeskelaeinen; D. G. Sarantites; F. A. Dilmanian; R. Woodward; H. Puchta; J. R. Beene; M. L. Halbert; J. Hattula; D. C. Hensley; J. H. Barker

    1981-01-01

    The population and decay of the entry states in ¹⁵⁷⁻sup 161\\/Yb and ¹⁵⁵⁻sup 158\\/Er from the reactions of 136- and 149-MeV ²°Ne with ¹⁴⁴Nd and ¹⁴⁶Nd have been investigated with the Spin Spectrometer gated with a Ge detector. Statistical-model calculations reproduce the main features of the entry state populations. The entry lines, as a function of multiplicity, M\\/sub ..gamma..\\/,

  2. Emergent spin

    SciTech Connect

    Creutz, Michael, E-mail: creutz@bnl.gov

    2014-03-15

    Quantum mechanics and relativity in the continuum imply the well known spin–statistics connection. However for particles hopping on a lattice, there is no such constraint. If a lattice model yields a relativistic field theory in a continuum limit, this constraint must “emerge” for physical excitations. We discuss a few models where a spin-less fermion hopping on a lattice gives excitations which satisfy the continuum Dirac equation. This includes such well known systems such as graphene and staggered fermions. -- Highlights: •The spin–statistics theorem is not required for particles on a lattice. •Spin emerges dynamically when spinless fermions have a relativistic continuum limit. •Graphene and staggered fermions are examples of this phenomenon. •The phenomenon is intimately tied to chiral symmetry and fermion doubling. •Anomaly cancellation is a crucial feature of any valid lattice fermion action.

  3. Adiabatic quantum computing with spin qubits hosted by molecules.

    PubMed

    Yamamoto, Satoru; Nakazawa, Shigeaki; Sugisaki, Kenji; Sato, Kazunobu; Toyota, Kazuo; Shiomi, Daisuke; Takui, Takeji

    2015-01-28

    A molecular spin quantum computer (MSQC) requires electron spin qubits, which pulse-based electron spin/magnetic resonance (ESR/MR) techniques can afford to manipulate for implementing quantum gate operations in open shell molecular entities. Importantly, nuclear spins, which are topologically connected, particularly in organic molecular spin systems, are client qubits, while electron spins play a role of bus qubits. Here, we introduce the implementation for an adiabatic quantum algorithm, suggesting the possible utilization of molecular spins with optimized spin structures for MSQCs. We exemplify the utilization of an adiabatic factorization problem of 21, compared with the corresponding nuclear magnetic resonance (NMR) case. Two molecular spins are selected: one is a molecular spin composed of three exchange-coupled electrons as electron-only qubits and the other an electron-bus qubit with two client nuclear spin qubits. Their electronic spin structures are well characterized in terms of the quantum mechanical behaviour in the spin Hamiltonian. The implementation of adiabatic quantum computing/computation (AQC) has, for the first time, been achieved by establishing ESR/MR pulse sequences for effective spin Hamiltonians in a fully controlled manner of spin manipulation. The conquered pulse sequences have been compared with the NMR experiments and shown much faster CPU times corresponding to the interaction strength between the spins. Significant differences are shown in rotational operations and pulse intervals for ESR/MR operations. As a result, we suggest the advantages and possible utilization of the time-evolution based AQC approach for molecular spin quantum computers and molecular spin quantum simulators underlain by sophisticated ESR/MR pulsed spin technology. PMID:25501117

  4. Shallow Donors in Silicon as Electron and Nuclear

    E-print Network

    Ahlers, Guenter

    · Electronics depends on the charge of the electron · Using the spin: spin transport electronics Datta-Das SpinShallow Donors in Silicon as Electron and Nuclear Spin Qubits Johan van Tol National High Magnetic computing · Spin qubits · Relaxation · Manipulation · Readout · FEL EPR #12;(Gordon) Moore's law · "The

  5. Structural characterization of sputtered hydrogenated amorphous carbon films by solid state nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Cho, Gyunggoo; Yen, Bing K.; Klug, Christopher A.

    2008-07-01

    Solid state nuclear magnetic resonance (NMR) methods have been used to investigate the effect of H content on the structure of sputtered hydrogenated amorphous carbon a-C:H films. Carbon-13 NMR spectra of a-C:H consist of two broad peaks at 135 and 40 ppm, which correspond to the sp2 and sp3 carbons, respectively. Surprisingly, the sp2/sp3 carbon ratio (2.0±0.3) is relatively independent of the H content in the range of 13%-35%. Hence, all a-C:H films contain approximately 66% graphitelike sp2 carbon. Cross polarization and spectral editing experiments reveal that the nonprotonated (quaternary) sp3 carbon fraction reaches as high as 30% at low H concentrations of 13%-23%. As the H content exceeds 23%, however, quaternary carbon bonds are terminated by H atoms to form protonated sp3 carbons, such as methylene (CH2) and methine (CH). Our results show that the hardness of a-C:H correlates with the quaternary carbon fraction rather than the sp2/sp3 ratio, as commonly believed. We also report the first extensive studies of both H1 and C13 spin-lattice relaxation for sputtered a-C:H. Relaxation data for hydrogen and carbon indicate that the unpaired electrons are probably equally distributed among sp2 and sp3 carbons. Moreover, the number of unpaired electrons in the a-C:H samples is relatively independent of H content, as revealed by spin counting experiments. C13 and H1 magnetization recovery curves for samples with H content up to 28% can be fitted with a single exponential, which is in contrast to the biexponential behavior reported for plasma-enhanced chemical vapor deposition (PECVD) a-C:H films. Hence, our results for sputtered a-C:H films do not support the model of proton-rich and proton-deficient regions proposed for PECVD carbon.

  6. Multi-planar image formation using NMR spin echoes

    Microsoft Academic Search

    P. Mansfield

    1977-01-01

    A new method of two- or three-dimensional spin density imaging by nuclear magnetic resonance (NMR) is proposed, which exploits the properties of spin echoes in time- dependent magnetic field gradients. An analysis shows that simultaneous observation and differentiation of signals, arising from all spins distributed in a plane or set of planes within the specimen, is possible. The method is

  7. Protein-tyrosyl radical interactions in photosystem II studied by electron spin resonance and electron nuclear double resonance spectroscopy: comparison with ribonucleotide reductase and in vitro tyrosine.

    PubMed

    Hoganson, C W; Babcock, G T

    1992-12-01

    The stable tyrosine radical in photosystem II, YD*, has been studied by ESR and ENDOR spectroscopies to obtain proton hyperfine coupling constants from which the electron spin density distribution can be deduced. Simulations of six previously published ESR spectra of PSII (one at Q band; five at X band, of which two were after specific deuteration and two others were of oriented membranes) can be achieved by using a single set of magnetic parameters that includes anisotropic proton hyperfine tensors, an anisotropic g tensor, and noncoincident axis systems for the g and A tensors. From the spectral simulation of the oriented samples, the orientation of the phenol head group of YD* with respect to the membrane plane has been determined. A similar orientation for YZ*, the redox-active tyrosine in PSII that mediates electron transfer between P680 and the oxygen-evolving complex, is expected. ENDOR spectra of YD* in PSII preparations from spinach and Synechocystis support the set of hyperfine coupling constants but indicate that small differences between the two species exist. Comparison with the results of spectral simulations for tyrosyl radicals in ribonucleotide reductase from prokaryotes or eukaryotes and with in vitro radicals indicates that the spin density distribution remains that of an odd-alternant radical but that interactions with the protein can shift spin density within this basic pattern. The largest changes in spin density occur at the tyrosine phenol oxygen and at the ring carbon para to the oxygen, which indicates that mechanisms exist in the protein environment for fine-tuning the chemical and redox properties of the radical species. PMID:1332777

  8. Nuclear Magnetic Resonance Spectroscopy

    NSDL National Science Digital Library

    2011-05-18

    This website serves as a primer for understanding the fundamentals of NMR spectroscopy. Plenty of useful figures and animations that enhance the understanding of nuclear spin, shielding, and how these phenomena serve as the basis for NMR.

  9. Classical gravitational spin-spin interaction

    E-print Network

    W. B. Bonnor

    2002-01-30

    I obtain an exact, axially symmetric, stationary solution of Einstein's equations for two massless spinning particles. The term representing the spin-spin interaction agrees with recently published approximate work. The spin-spin force appears to be proportional to the inverse fourth power of the coordinate distance between the particles.

  10. Imaging spin injection & spin transport in semiconductors

    E-print Network

    Duisburg-Essen, Universität

    /off switching of current (resistance) via spin orientation · Exploits spin of electrons Datta & Das, Appl. PhysImaging spin injection & spin transport in semiconductors Scott Crooker National High Magnetic Garlid & Paul Crowell School of Physics and Astronomy, University of Minnesota 50 m Imaging spin

  11. A Straightforward Way to Determine Relative Intensities of Spin-Spin Splitting Lines of Equivalent Nuclei in NMR Spectra.

    ERIC Educational Resources Information Center

    Orcutt, Ronald H.

    1987-01-01

    Describes a simple way of obtaining a set of relative intensities of spin-spin splitting lines using Pascal's triangle rather than calculating binomial coefficients. Provides tables showing Pascal's triangle and the relative intensities of multiplets for a range of nuclear spins. (TW)

  12. First Evidence of Double Spin Isospin Excitation

    NASA Astrophysics Data System (ADS)

    Takahisa, Keiji

    2007-06-01

    To study double spin-isospin responses in view of the ??0? decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. This is the first evidence of double spin isospin excitation. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher ?L excitations.

  13. First Evidence of Double Spin Isospin Excitation

    SciTech Connect

    Takahisa, Keiji [Research Center for Nuclear Physics, Osaka University, Mihogaoka 10-1, Ibaraki, Osaka, 567-0047 (Japan)

    2007-06-13

    To study double spin-isospin responses in view of the {beta}{beta}0{nu} decays, double charge-exchange nuclear reactions have measured at RCNP. We have succeeded to measure the double charge exchange reaction by means of heavy ion reaction. From these experiments, we conclude that the (11B,11Li) reaction at 70 MeV/nucleon is a good spectroscopic tool. This is the first evidence of double spin isospin excitation. We believe that the reaction can be well applied to the study of pure spin-flip nuclear responses in higher-excited regions including DGT and higher {delta}L excitations.

  14. Spin distribution of the H-cluster in the H(ox)-CO state of the [FeFe] hydrogenase from Desulfovibrio desulfuricans: HYSCORE and ENDOR study of (14)N and (13)C nuclear interactions.

    PubMed

    Silakov, Alexey; Wenk, Brian; Reijerse, Eduard; Albracht, Simon P J; Lubitz, Wolfgang

    2009-02-01

    Hydrogenases are enzymes which catalyze the reversible cleavage of molecular hydrogen into protons and electrons. In [FeFe] hydrogenases the active center is a 6Fe6S cluster, referred to as the "H-cluster." It consists of the redox-active binuclear subcluster ([2Fe](H)) coordinated by CN(-) and CO ligands and the cubane-like [4Fe-4S](H) subcluster which is connected to the protein via Cys ligands. One of these Cys ligands bridges to the [2Fe](H) subcluster. The CO-inhibited form of [FeFe] hydrogenase isolated from Desulfovibrio desulfuricans was studied using advanced EPR methods. In the H(ox)-CO state the open coordination site at the [2Fe](H) subcluster is blocked by extrinsic CO, giving rise to an EPR-active S = 1/2 species. The CO inhibited state was prepared with (13)CO and illuminated under white light at 273 K. In this case scrambling of the CO ligands occurs. Three (13)C hyperfine couplings of 17.1, 7.4, and 3.8 MHz (isotropic part) were observed and assigned to (13)CO at the extrinsic, the bridging, and the terminal CO-ligand positions of the distal iron, respectively. No (13)CO exchange of the CO ligand to the proximal iron was observed. The hyperfine interactions detected indicate a rather large distribution of the spin density over the terminal and bridging CO ligands attached to the distal iron. Furthermore, (14)N nuclear spin interactions were measured. On the basis of the observed (14)N hyperfine couplings, which result from the CN(-) ligands of the [2Fe](H) subcluster, it has been concluded that there is very little unpaired spin density on the cyanides of the binuclear subcluster. PMID:19011912

  15. Experimental data confronts nuclear structure

    SciTech Connect

    Garrett, J.D.

    1988-01-01

    The physical content of experimental data for a variety of excitation energies and angular momenta is summarized. The specific nuclear structure questions which these data address are considered. The specific regions discussed are: low-spin data near the particle separation thresholds; low-spin data at intermediate excitation energies; high-spin, near-yrast data and high-spin data at larger excitation energies. 63 refs., 14 figs., 1 tab.

  16. Effectiveness of classical spin simulations for describing NMR relaxation of quantum spins

    NASA Astrophysics Data System (ADS)

    Elsayed, Tarek A.; Fine, Boris V.

    2015-03-01

    We investigate the limits of effectiveness of classical spin simulations for predicting free induction decays (FIDs) measured by solid-state nuclear magnetic resonance on systems of quantum nuclear spins. The specific limits considered are associated with the range of interaction, the size of individual quantum spins, and the long-time behavior of the FID signals. We compare FIDs measured or computed for lattices of quantum spins (mainly spins 1/2) with the FIDs computed for the corresponding lattices of classical spins. Several cases of excellent quantitative agreement between quantum and classical FIDs are reported along with the cases of gradually decreasing quality of the agreement. We formulate semiempirical criteria defining the situations, when classical simulations are expected to accurately reproduce quantum FIDs. Our findings indicate that classical simulations may be a quantitatively accurate tool of first-principles calculations for a broad class of macroscopic systems, where individual quantum microscopic degrees of freedom are far from the classical limit.

  17. (13)C spin-lattice relaxation in nanodiamonds in static and magic angle spinning regimes.

    PubMed

    Sergeev, N A; Panich, A M; Olszewski, M; Shenderova, O; Goren, S D

    2015-01-01

    We report on (13)C nuclear spin-lattice relaxation time (T1) dependence on the magic-angle-spinning (MAS) rate in powder nanodiamond samples. We confirm that the relaxation is caused by interaction of nuclear spins with fluctuating electron spins of localized paramagnetic defects. It was found that T1 is practically not affected by MAS for small particles, while for larger particles with lower defect density T1 is different in static and MAS regimes and reveals elongation with increasing MAS rate. This effect is attributed to suppression of nuclear spin diffusion by MAS. We propose an approach that describes T1 dependence on the MAS rate and allows quantitative analysis of this effect. PMID:25465482

  18. Research highlights with the spin spectrometer

    SciTech Connect

    Sarantites, D.G.; Jaeaeskelaeinen, M.; Dilmanian, F.A.; Puchta, H.; Woodward, R.; Beene, J.R.; Hensley, D.C.; Halbert, M.L.; Hattula, J.; Barker, J.H.

    1982-01-01

    The excitation energy and angular momentum dependence of the entry states in fusion reactions measured with the spin spectrometer is discussed. A new decay mode involving the onset of localized stretched dipole radiation at half the accompanying stretched E2 collective radiation is found in /sup 157 -161/Yb. The appearance of this mode correlates smoothly with neutron number and spin. Possible interpretations are presented in terms of the evolution of the nuclear shapes from prolate to aligned-quasiparticle oblate to collective oblate and then to triaxial. Evidence for nuclear deformation that increases with spin at very high excitation is presented based on ..cap alpha..-particle angular distributions measured relative to the spin direction, using a new method for deriving the spin alignment.

  19. Spin ejector

    DOEpatents

    Andersen, John A. (Alburquerque, NM); Flanigan, John J. (Alburquerque, NM); Kindley, Robert J. (Alburquerque, NM)

    1978-01-01

    The disclosure relates to an apparatus for spin ejecting a body having a flat plate base containing bosses. The apparatus has a base plate and a main ejection shaft extending perpendicularly from the base plate. A compressible cylindrical spring is disposed about the shaft. Bearings are located between the shaft and the spring. A housing containing a helical aperture releasably engages the base plate and surrounds the shaft bearings and the spring. A piston having an aperture follower disposed in the housing aperture is seated on the spring and is guided by the shaft and the aperture. The spring is compressed and when released causes the piston to spin eject the body.

  20. Evolution of Nuclear Spectra with Nuclear Forces

    E-print Network

    R. B. Wiringa; Steven C. Pieper

    2002-07-16

    We first define a series of NN interaction models ranging from very simple to fully realistic. We then present Green's function Monte Carlo calculations of light nuclei to show how nuclear spectra evolve as the nuclear forces are made increasingly sophisticated. We find that the absence of stable five- and eight-body nuclei depends crucially on the spin, isospin, and tensor components of the nuclear force.

  1. Quantum discord in the central spin model

    E-print Network

    V. E. Zobov

    2014-11-14

    The quantum properties of dynamic correlations in a system of an electron spin surrounded by nuclear spins under the conditions of free induction decay (FID) and spin echo have been studied. Analytical results for the time evolution of mutual information, classical part of correlations, and quantum part characterized by quantum discord have been obtained within the central spin model in the high-temperature approximation. The same formulas describe the quantum discord in both the FID and the spin echo although the forms of the dependences are different because of difference in the parameters entering into the formulas. Discord of the spin echo compared with the FID has a strong dependence on time at short times, and it tends to zero with decreasing of the magnetic field, whereas in the case of the FID it reaches a plateau.

  2. Relaxation-optimized transfer of spin order in Ising spin chains

    SciTech Connect

    Stefanatos, Dionisis; Khaneja, Navin [Division of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138 (United States); Glaser, Steffen J. [Department of Chemistry, Technische Universitaet Muenchen, 85747 Garching (Germany)

    2005-12-15

    In this paper, we present relaxation optimized methods for the transfer of bilinear spin correlations along Ising spin chains. These relaxation optimized methods can be used as a building block for the transfer of polarization between distant spins on a spin chain, a problem that is ubiquitous in multidimensional nuclear magnetic resonance spectroscopy of proteins. Compared to standard techniques, significant reduction in relaxation losses is achieved by these optimized methods when transverse relaxation rates are much larger than the longitudinal relaxation rates and comparable to couplings between spins. We derive an upper bound on the efficiency of the transfer of the spin order along a chain of spins in the presence of relaxation and show that this bound can be approached by the relaxation optimized pulse sequences presented in the paper.

  3. Optical control of one and two hole spins in interacting quantum dots

    Microsoft Academic Search

    Alex Greilich; Samuel G. Carter; Danny Kim; Allan S. Bracker; Daniel Gammon

    2011-01-01

    A single hole spin in a semiconductor quantum dot has emerged as a quantum bit that is potentially superior to an electron spin. A key feature of holes is that they have a greatly reduced hyperfine interaction with nuclear spins, which is one of the biggest difficulties in working with an electron spin. It is now essential to show that

  4. RHIC SPIN FLIPPER COMMISSIONING.

    SciTech Connect

    BAI,M.LUCCIO,A.U.MACKAY,W.W.RANJBAR,V.ROSER,T.

    2002-09-09

    An ac dipole with horizontally oriented oscillating magnetic field (spin flipper) was installed in RHIC to reverse the spin direction in the presence of two full Siberian snakes, thereby reducing the systematic errors for the spin physics experiments in RHIC. With two full snakes, the spin vector completes one full precession around the vertical direction in two revolutions, and the spin depolarization resonances due to the machine imperfections and betatron oscillations are eliminated. Since the spin flipper provides an oscillating horizontal dipole field, a ''spin resonance'' can occur if the spin flipper frequency is placed in the neighborhood of the spin precession frequency [1,2,3]. By slowly sweeping the spin flipper frequency across the spin precession frequency, a full spin flip can be achieved. This paper reports the results of the RHIC spin flipper commissioned during the RHIC 2002 polarized proton run. By running the spin flipper at a slightly different configuration, one can also measure the spin precession tune.

  5. A quantum spin transducer based on nanoelectromechanical resonator arrays

    NASA Astrophysics Data System (ADS)

    Rabl, P.; Kolkowitz, S. J.; Koppens, F. H. L.; Harris, J. G. E.; Zoller, P.; Lukin, M. D.

    2010-08-01

    Isolated electronic and nuclear spins in solids are at present being actively explored for potential quantum-computing applications. Spin degrees of freedom provide an excellent quantum memory, owing to their weak magnetic interactions with the environment. For the same reason, however, it is difficult to achieve controlled interactions of spins over distances larger than tens of nanometres. Here we propose a new realization of a quantum data bus for spin qubits where spins are coupled to the motion of magnetized mechanical resonators through magnetic-field gradients. Provided that the mechanical system is charged, the magnetic moments associated with spin qubits can be effectively amplified to enable a coherent spin-spin coupling over long distances through Coulomb forces. Our approach is applicable to a wide class of electronic spin qubits, which can be localized near magnetized tips and can be used for the implementation of hybrid quantum-computing architectures.

  6. Spin pumping and spin Seebeck effect

    NASA Astrophysics Data System (ADS)

    Saitoh, Eiji

    2012-02-01

    Utilization of a spin current, a flow of electrons' spins in a solid, is the key technology in spintronics that will allow the achievement of efficient magnetic memories and computing devices. In this technology, generation and detection of spin currents are necessary. Here, we review inverse spin-Hall effect and spin-current-generation phenomena recently discovered both in metals and insulators: inverse spin-Hall effect, spin pumping, and spin Seebeck effect. (1)Spin pumping and spin torque in a Mott insulator system We found that spin pumping and spin torque effects appear also at an interface between Pt and an insulator YIG.. This means that we can connect a spin current carried by conduction electrons and a spin-wave spin current flowing in insulators. We demonstrate electric signal transmission by using these effects and interconversion of the spin currents [1]. (2) Spin Seebeck effect We have observed, by using the inverse spin-Hall effect [2], spin voltage generation from a heat current in a NiFe, named the spin-Seebeck effect [3]. Surprisingly, spin-Seebeck effect was found to appear even in insulators [4], a situation completely different from conventional charge Seebeck effect. The result implies an important role of elementary excitation in solids beside charge in the spin Seebeck effect. In the talk, we review the recent progress of the research on this effect. This research is collaboration with K. Ando, K. Uchida, Y. Kajiwara, S. Maekawa, G. E. W. Bauer, S. Takahashi, and J. Ieda. [4pt] [1] Y. Kajiwara and E. Saitoh et al. Nature 464 (2010) 262. [0pt] [2] E. Saitoh et al., Appl. Phys. Lett. 88 (2006) 182509. [0pt] [3] K. Uchida and E. Saitoh et al., Nature 455 (2008)778. [0pt] [4] K. Uchida and E. Saitoh et al.,Nature materials 9 (2010) 894 - 897.

  7. Quantum Decoherence of the Central Spin in a Sparse System of Dipolar Coupled Spins

    E-print Network

    Wayne M. Witzel; Malcolm S. Carroll; Lukasz Cywinski; S. Das Sarma

    2012-08-02

    The central spin decoherence problem has been researched for over 50 years in the context of both nuclear magnetic resonance and electron spin resonance. Until recently, theoretical models have employed phenomenological stochastic descriptions of the bath-induced noise. During the last few years, cluster expansion methods have provided a microscopic, quantum theory to study the spectral diffusion of a central spin. These methods have proven to be very accurate and efficient for problems of nuclear-induced electron spin decoherence in which hyperfine interactions with the central electron spin are much stronger than dipolar interactions among the nuclei. We provide an in-depth study of central spin decoherence for a canonical scale-invariant all-dipolar spin system. We show how cluster methods may be adapted to treat this problem in which central and bath spin interactions are of comparable strength. Our extensive numerical work shows that a properly modified cluster theory is convergent for this problem even as simple perturbative arguments begin to break down. By treating clusters in the presence of energy detunings due to the long-range (diagonal) dipolar interactions of the surrounding environment and carefully averaging the effects over different spin states, we find that the nontrivial flip-flop dynamics among the spins becomes effectively localized by disorder in the energy splittings of the spins. This localization effect allows for a robust calculation of the spin echo signal in a dipolarly coupled bath of spins of the same kind, while considering clusters of no more than 6 spins. We connect these microscopic calculation results to the existing stochastic models. We, furthermore, present calculations for a series of related problems of interest for candidate solid state quantum bits including donors and quantum dots in silicon as well as nitrogen-vacancy centers in diamond.

  8. PREFACE: SPIN2010 - Preface for Conference Proceedings

    NASA Astrophysics Data System (ADS)

    Ströher, Hans; Rathmann, Frank

    2011-03-01

    SPIN2010, the 19th International Spin Physics Symposium, took place between 27 September and 2 October, 2010 on the campus of Forschungszentrum Jülich GmbH (FZJ) in Jülich, Germany. The scientific program of this Symposium included many topics related to spin phenomena in particle and nuclear physics as well as those in related fields. The International Spin Physics Symposium series has combined the High Energy Spin Symposia and the Nuclear Polarization Conferences since 2000. The most recent two Symposia were held in Virginia, USA (October 2008) and in Kyoto, Japan (October 2006). The meeting was opened by the chairman of the Board of Management of Jülich Forschungszentrum, Professor Achim Bachem, who cordially welcomed the participants from all over the world and gave a brief introduction to the Center and the research conducted there. The scientific program consisted of plenary sessions and parallel sessions and included the following topics: Fundamental symmetries and spin Spin structure of hadrons Spin physics beyond the Standard Model Spin in hadronic reactions Spin physics with photons and leptons Spin physics in nuclear reactions and nuclei Acceleration, storage, and polarimetry of polarized beams Polarized ion and lepton sources and targets Future facilities and experiments Medical and technological applications of spin physics The 6-day symposium had about 300 participants. In total 35 plenary talks (including 3 summaries of other spin physics meetings) and 163 contributed talks were given. The contents of many of these can be found in the present contributions, arranged according to the above topics and the time sequence. In addition, a public lecture on "Drall in der Quantenwelt", presented by H O Meyer (Bloomington) was received very well. Participants had the option to visit the Cooler synchrotron COSY at the Nuclear Physics Institute (IKP) and the 9.4 T MRT-PET hybrid scanner at the Institute of Neuroscience and Medicine (INM), two unique facilities at FZJ, and many made the most of the opportunity. We gratefully acknowledge the financial support from Brookhaven National Laboratory (BNL, USA), Forschungszentrum Jülich (FZJ), the International Union of Pure And Applied Physics (IUPAP), Thomas Jefferson Laboratory (JLab, USA), Helmholtz Institute Mainz (HIM, Germany) and the Virtual Institute on Spin and Strong QCD (VI-QCD) of the Helmholtz Association (HGF). We would also like to thank the local people from IKP and other institutions of FZJ for their contributions and help - without them we would not have been able to organize this great meeting. The current proceedings comprise written contributions of many of the presentations during SPIN2010; however, due to the recent incident in Japan, a number of our colleagues from there were unfortunately not able to deliver their write-ups in due time. This volume was edited by Ralf Gebel, Christoph Hanhart, Andro Kacharava, Andreas Lehrach, Bernd Lorentz, Nikolai N Nikolaev, Andreas Nogga, Frank Rathmann, and Hans Ströher. The next symposium - SPIN2012 - will be held at the Joint Institute for Nuclear Research (JINR) in Dubna (Russia) in 2012. We are looking forward to meeting you there. Important conference-related links: SPIN2010 Web-site: https://www.congressa.de/SPIN2010/ Article in CERN Courier: http://cerncourier.com/cws/article/cern/45451 Spin Physics Committee: http://www.spin-community.org Jülich, April 2011 - Hans Ströher, Frank Rathmann (Chairs SPIN2010) Conference photograph

  9. Interpretation of the longitudinal (13)C nuclear spin relaxation and chemical shift data for five bromoazaheterocycles supported by nonrelativistic and relativistic DFT calculations.

    PubMed

    Wody?ski, Artur; Kraska-Dziadecka, Anna; Kubica, Dominika; Gryff-Keller, Adam

    2015-01-22

    The longitudinal relaxation times of (13)C nuclei and NOE enhancement factors for 2-bromopyridine (1), 6-bromo-9-methylpurine (2), 3,5-dibromopyridine (3), 2,4-dibromopyrimidine (4), and 2,4,6-tribromopyrimidine (5) have been measured at 25 °C and B0 = 11.7 T. The most important contributions to the overall relaxation rates of nonbrominated carbons, i.e., the relaxation rates due to the (13)C-(1)H dipolar interactions and the shielding anisotropy mechanism, have been separated out. For 3 and 5, additionally, the T2,Q((14)N) values have been established from (14)N NMR line widths. All of these data have been used to determine rotational diffusion tensors for the investigated molecules. The measured saturation recovery curves of brominated carbons have been decomposed into two components to yield relaxation times, which after proper corrections provided parameters characterizing the scalar relaxation of the second kind for (13)C nuclei of (79)Br- and (81)Br-bonded carbons. These parameters and theoretically calculated quadrupole coupling constants for bromine nuclei have allowed the values of one-bond (13)C-(79)Br spin-spin coupling constants to be calculated. Independently, the coupling constants and magnetic shielding constants of the carbon nuclei have been calculated theoretically using the nonrelativistic and relativistic DFT methods F/6-311++G(2d,p)/PCM and so-ZORA/F/TZ2P/COSMO (F = BHandH or B3LYP), respectively. The agreement between the experimental and theoretical values of these parameters is remarkably dependent on the theoretical method used. PMID:25536066

  10. Hybridization and Spin Decoherence in Heavy-Hole Quantum Dots

    NASA Astrophysics Data System (ADS)

    Fischer, Jan; Loss, Daniel

    2010-12-01

    We theoretically investigate the spin dynamics of a heavy hole confined to an unstrained III-V semiconductor quantum dot and interacting with a narrowed nuclear-spin bath. We show that band hybridization leads to an exponential decay of hole-spin superpositions due to hyperfine-mediated nuclear pair flips, and that the accordant single-hole-spin decoherence time T2 can be tuned over many orders of magnitude by changing external parameters. In particular, we show that, under experimentally accessible conditions, it is possible to suppress hyperfine-mediated nuclear-pair-flip processes so strongly that hole-spin quantum dots may be operated beyond the “ultimate limitation” set by the hyperfine interaction which is present in other spin-qubit candidate systems.

  11. Single-atom spin qubits in silicon

    NASA Astrophysics Data System (ADS)

    Dzurak, Andrew

    2013-03-01

    Spin qubits in silicon are excellent candidates for scalable quantum information processing (QIP) due to their long coherence times and the enormous investment in silicon MOS technology. Here I discuss qubits based upon single phosphorus (P) dopant atoms in Si [1]. Projective readout of such qubits had proved challenging until single-shot measurement of a single donor electron spin was demonstrated [2] using a silicon single electron transistor (Si-SET) and the process of spin-to-charge conversion. The measurement gave readout fidelities 90% and spin lifetimes T1e 6 s [2], opening the path to demonstration of electron and nuclear spin qubits in silicon. Integrating an on-chip microwave transmission line enabled single-electron spin resonance (ESR) of the P donor electron. We used this to demonstrate Rabi oscillations of the electron spin qubit, while a Hahn echo sequence revealed electron spin coherence times T2e 0.2 ms [3]. This time is expected to become much longer in isotopically enriched ^28Si devices. We also achieved single-shot readout of the ^31P nuclear spin (with fidelity 99.6%) by monitoring the two hyperfine-split ESR lines of the P donor system. By applying (local) NMR pulses we demonstrated coherent control of the nuclear spin qubit, giving a coherence time T2n 60 ms. [4pt] [1] B.E. Kane, Nature 393, 133 (1998). [2] A. Morello et al., Nature 467, 687 (2010). [3] J.J. Pla et al., Nature 489, 541 (2012).

  12. Spin quantum computation in silicon nanostructures

    E-print Network

    S. Das Sarma; Rogerio de Sousa; Xuedong Hu; Belita Koiller

    2004-11-30

    Proposed silicon-based quantum-computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing Si technology infrastructure. Electronic and nuclear spins of shallow donors (e.g. phosphorus) in Si are ideal candidates for qubits in such proposals because of their long spin coherence times due to their limited interactions with their environments. For these spin qubits, shallow donor exchange gates are frequently invoked to perform two-qubit operations. We discuss in this review a particularly important spin decoherence channel, and bandstructure effects on the exchange gate control. Specifically, we review our work on donor electron spin spectral diffusion due to background nuclear spin flip-flops, and how isotopic purification of silicon can significantly enhance the electron spin dephasing time. We then review our calculation of donor electron exchange coupling in the presence of degenerate silicon conduction band valleys. We show that valley interference leads to orders of magnitude variations in electron exchange coupling when donor configurations are changed on an atomic scale. These studies illustrate the substantial potential that donor electron/nuclear spins in silicon have as candidates for qubits and simultaneously the considerable challenges they pose. In particular, our work on spin decoherence through spectral diffusion points to the possible importance of isotopic purification in the fabrication of scalable solid state quantum computer architectures. We also provide a critical comparison between the two main proposed spin-based solid state quantum computer architectures, namely, shallow donor bound states in Si and localized quantum dot states in GaAs.

  13. Spin quantum computation in silicon nanostructures

    NASA Astrophysics Data System (ADS)

    Sarma, S. Das; Sousa, Rogerio de; Hu, Xuedong; Koiller, Belita

    2005-03-01

    Proposed silicon-based quantum-computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing Si technology infrastructure. Electronic and nuclear spins of shallow donors (e.g. phosphorus) in Si are ideal candidates for qubits in such proposals because of their long spin coherence times due to their limited interactions with their environments. For these spin qubits, shallow donor exchange gates are frequently invoked to perform two-qubit operations. We discuss in this review a particularly important spin decoherence channel, and bandstructure effects on the exchange gate control. Specifically, we review our work on donor electron spin spectral diffusion due to background nuclear spin flip-flops, and how isotopic purification of silicon can significantly enhance the electron spin dephasing time. We then review our calculation of donor electron exchange coupling in the presence of degenerate silicon conduction band valleys. We show that valley interference leads to orders of magnitude variations in electron exchange coupling when donor configurations are changed on an atomic scale. These studies illustrate the substantial potential that donor electron/nuclear spins in silicon have as candidates for qubits and simultaneously the considerable challenges they pose. In particular, our work on spin decoherence through spectral diffusion points to the possible importance of isotopic purification in the fabrication of scalable solid state quantum computer architectures. We also provide a critical comparison between the two main proposed spin-based solid state quantum computer architectures, namely, shallow donor bound states in Si and localized quantum dot states in GaAs.

  14. Implementation of State Transfer Hamiltonians in Spin Chains with Magnetic Resonance Techniques

    E-print Network

    Cappellaro, Paola

    2014-01-01

    Nuclear spin systems and magnetic resonance techniques have provided a fertile platform for experimental investigation of quantum state transfer in spin chains. From the first observation of polarization transfer, predating ...

  15. Resolving Spin-Orbit- and Hyperfine-Mediated Electric Dipole Spin Resonance in a Quantum Dot

    NASA Astrophysics Data System (ADS)

    Shafiei, M.; Nowack, K. C.; Reichl, C.; Wegscheider, W.; Vandersypen, L. M. K.

    2013-03-01

    We investigate the electric manipulation of a single-electron spin in a single gate-defined quantum dot. We observe that so-far neglected differences between the hyperfine- and spin-orbit-mediated electric dipole spin resonance conditions have important consequences at high magnetic fields. In experiments using adiabatic rapid passage to invert the electron spin, we observe an unusually wide and asymmetric response as a function of the magnetic field. Simulations support the interpretation of the line shape in terms of four different resonance conditions. These findings may lead to isotope-selective control of dynamic nuclear polarization in quantum dots.

  16. Nuclear Magnetic Resonance Technology for Medical Studies

    NASA Astrophysics Data System (ADS)

    Budinger, Thomas F.; Lauterbur, Paul C.

    1984-10-01

    Nuclear magnetic resonance proton imaging provides anatomical definition of normal and abnormal tissues with a contrast and detection sensitivity superior to those of x-ray computed tomography in the human head and pelvis and parts of the cardiovascular and musculoskeletal systems. Recent improvements in technology should lead to advances in diagnostic imaging of the breast and regions of the abdomen. Selected-region nuclear magnetic resonance spectroscopy of protons, carbon-13, and phosphorus-31 has developed into a basic science tool for in vivo studies on man and a unique tool for clinical diagnoses of metabolic disorders. At present, nuclear magnetic resonance is considered safe if access to the magnet environment is controlled. Technological advances employing field strengths over 2 teslas will require biophysical studies of heating and static field effects.

  17. Optical pumping production of spin polarized hydrogen

    SciTech Connect

    Knize, R.J.; Happer, W.; Cecchi, J.L.

    1984-09-01

    There has been much interest recently in the production of large quantities of spin polarized hydrogen in various fields, including controlled fusion, quantum fluids, high energy, and nuclear physics. One promising method for the development of large quantities of spin polarized hydrogen is the utilization of optical pumping with a laser. Optical pumping is a process in which photon angular momentum is converted into electron and nuclear spin. The advent of tunable CW dye lasers (approx. 1 watt) allows the production of greater than 10/sup 18/ polarized atoms/sec. We have begun a program at Princeton to investigate the physics and technology of using optical pumping to produce large quantities of spin polarized hydrogen. Initial experiments have been done in small closed glass cells. Eventually, a flowing system, open target, or polarized ion source could be constructed.

  18. Nuclear effects in atomic transitions

    Microsoft Academic Search

    Adriana Palffy

    2010-01-01

    Atomic electrons are sensitive to the properties of the nucleus they are bound to, such as nuclear mass, charge distribution, spin, magnetization distribution, or even excited level scheme. These nuclear parameters are reflected in the atomic transition energies. A very precise determination of atomic spectra may thus reveal information about the nucleus, otherwise hardly accessible via nuclear physics experiments. This

  19. Spin quantum computation in silicon nanostructures

    Microsoft Academic Search

    S. Das Sarma; Rogerio de Sousa; Xuedong Hu; Belita Koiller

    2005-01-01

    Proposed silicon-based quantum-computer architectures have attracted attention because of their promise for scalability and their potential for synergetically utilizing the available resources associated with the existing Si technology infrastructure. Electronic and nuclear spins of shallow donors (e.g. phosphorus) in Si are ideal candidates for qubits in such proposals because of their long spin coherence times due to their limited interactions

  20. Nuclear scales

    SciTech Connect

    Friar, J.L.

    1998-12-01

    Nuclear scales are discussed from the nuclear physics viewpoint. The conventional nuclear potential is characterized as a black box that interpolates nucleon-nucleon (NN) data, while being constrained by the best possible theoretical input. The latter consists of the longer-range parts of the NN force (e.g., OPEP, TPEP, the {pi}-{gamma} force), which can be calculated using chiral perturbation theory and gauged using modern phase-shift analyses. The shorter-range parts of the force are effectively parameterized by moments of the interaction that are independent of the details of the force model, in analogy to chiral perturbation theory. Results of GFMC calculations in light nuclei are interpreted in terms of fundamental scales, which are in good agreement with expectations from chiral effective field theories. Problems with spin-orbit-type observables are noted.

  1. Nuclear Magnetic Resonance Coupling Constants and Electronic Structure in Molecules.

    ERIC Educational Resources Information Center

    Venanzi, Thomas J.

    1982-01-01

    Theory of nuclear magnetic resonance spin-spin coupling constants and nature of the three types of coupling mechanisms contributing to the overall spin-spin coupling constant are reviewed, including carbon-carbon coupling (neither containing a lone pair of electrons) and carbon-nitrogen coupling (one containing a lone pair of electrons).…

  2. Structural characterization and physical properties of P2O5-CaO-Na2O-TiO2 glasses by Fourier transform infrared, Raman and solid-state magic angle spinning nuclear magnetic resonance spectroscopies.

    PubMed

    Kiani, Azadeh; Hanna, John V; King, Scott P; Rees, Gregory J; Smith, Mark E; Roohpour, Nima; Salih, Vehid; Knowles, Jonathan C

    2012-01-01

    Phosphate-based glasses have been investigated for tissue engineering applications. This study details the properties and structural characterization of titanium ultra-phosphate glasses in the 55(P(2)O(5))-30(CaO)-(25-x)(Na(2)O)-x(TiO(2)) (0?x?5) system, which have been prepared via melt-quenching techniques. Structural characterization was achieved by a combination of X-ray diffraction (XRD), and solid-state nuclear magnetic resonance, Raman and Fourier transform infrared spectroscopies. Physical properties were also investigated using density, degradation and ion release studies; additionally, differential thermal analysis was used for thermal analysis of these glasses. The results show that with the addition of TiO(2) the density and glass transition temperature increased whereas the degradation and ion release properties are decreased. From XRD data, TiP(2)O(7) and CaP(2)O(6) were detected in 3 and 5 mol.% TiO(2)-containing glasses. Magic angle spinning nuclear magnetic resonance results confirmed that as TiO(2) is incorporated into the glass; the amount of Q(3) increases as the amount of Q(2) consequently decreases, indicating increasing polymerization of the phosphate network. Spectroscopy results also showed that the local structure of glasses changes with increasing TiO(2) content. As TiO(2) is incorporated into the glass, the phosphate connectivity increases, indicating that the addition of TiO(2) content correlates unequivocally with an increase in glass stability. PMID:21930253

  3. Solid-State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 1. Crystallinity, Morphology, and the Direct Influence of Fe3+ on Nuclear Spins

    NSDL National Science Digital Library

    Vanderhart, D. L.

    2001-01-01

    Several exfoliated nylon-6/clay nanocomposites (NnC’s) were investigated and compared with pure nylon-6 using solid-state NMR, both proton and 13C. NnC’s had nominally 5 mass % clay and were generated both by blending and by in situ polymerization (IsP). Most of the studied NnC’s contained layered, naturally occurring montmorillonite clays having nonstoichiometric amounts of nonexchangeable Mg2+ and Fe3+ ions that substitute into octahedral Al3+ sites along the midplane of the 1-nm-thick clay layers. The Fe3+ ions impart a useful paramagnetism to the clay. Each Mg2+ ion leaves an embedded negative charge that must be neutralized with some cation at the surface of the clay. All clays were initially treated with a cationic so-called organic modifier (OM), often a substituted ammonium ion, which increases the clay layer spacing, attaching ionically to the surface of the clay layers. Clay is found to promote growth of the ç-crystalline phase of nylon-6 for both blended and IsP NnC’s; R-crystallites are characteristic of the pure nylon-6. Stability of the ç-phase to annealing at 214 °C was investigated. Conversion of ç- to R-crystallinity during annealing was minimal, except for an injection-molded IsP NnC, which had been exposed to a temperature of 295 °C during molding. This high processing temperature produced an irreversible change. An attempt was made to understand, at least qualitatively, the nature of the spectral density of magnetic fluctuations associated with the paramagnetic Fe3+ sites in the clay. For this purpose, we looked directly at the influence of Fe3+ on the 13C and proton observables in organically modified clays (OMC). We agree with other investigators that the spectral density of paramagnetic fluctuations at the surface of the clay is determined mainly by spin-exchange interactions between Fe3+ sites; thus, the spectral density can be altered by changing the Fe3+ concentration. Moreover, we find that the spectral density is very wide, having strong contributions all the way from mid-kHz fluctuations to MHz fluctuations near the proton Larmor frequencies. Significant variations in the R/ç ratio were also observed in the injection-molded disk, which reflect either a processing-induced heterogeneity in clay dispersion or a significant variation in cooling history from region to region. Proton spin diffusion and multiple-pulse methods were utilized to compare morphologies for a diamagnetic NnC and nylon-6 with the same thermal histories. Long spacing, crystallinity, and the mobility of the noncrystalline nylon-6 segments are very similar for NnC’s and nylon-6.

  4. Seeing spin dynamics in atomic gases

    E-print Network

    Dan M. Stamper-Kurn

    2014-12-31

    The dynamics of internal spin, electronic orbital, and nuclear motion states of atoms and molecules have preoccupied the atomic and molecular physics community for decades. Increasingly, such dynamics are being examined within many-body systems composed of atomic and molecular gases. Our findings sometimes bear close relation to phenomena observed in condensed-matter systems, while on other occasions they represent truly new areas of investigation. I discuss several examples of spin dynamics that occur within spinor Bose-Einstein gases, highlighting the advantages of spin-sensitive imaging for understanding and utilizing such dynamics.

  5. Mechanism of Solid-State Thermolysis of Ammonia Boraine: 15N NMR Study Using Fast Magic-Angle Spinning and Dynamic Nuclear Polarization

    SciTech Connect

    Kobayashi, Takeshi [Ames Laboratory; Gupta, Shalabh [Ames Laboratory; Caporini, Marc A [Bruker BioSpin Corporation; Pecharsky, Vitalij K [Ames Laboratory; Pruski, Marek [Ames Laboratory

    2014-08-28

    The solid-state thermolysis of ammonia borane (NH3BH3, AB) was explored using state-of-the-art 15N solid-state NMR spectroscopy, including 2D indirectly detected 1H{15N} heteronuclear correlation and dynamic nuclear polarization (DNP)-enhanced 15N{1H} cross-polarization experiments as well as 11B NMR. The complementary use of 15N and 11B NMR experiments, supported by density functional theory calculations of the chemical shift tensors, provided insights into the dehydrogenation mechanism of AB—insights that have not been available by 11B NMR alone. Specifically, highly branched polyaminoborane derivatives were shown to form from AB via oligomerization in the “head-to-tail” manner, which then transform directly into hexagonal boron nitride analog through the dehydrocyclization reaction, bypassing the formation of polyiminoborane.

  6. Single-crystal and powder electron-nuclear double resonance of RbCl:O-2: A comparison between the spin Hamiltonian parameters obtained from both experiments

    NASA Astrophysics Data System (ADS)

    van Doorslaer, S.; Callens, F.; Maes, F.; Boesman, E.

    1995-05-01

    In this work a single-crystal ENDOR study of RbCl:O-2 is presented. The angular variation of two sets of 85Rb and 87Rb ENDOR transitions is investigated. The corresponding superhyperfine (SHF) and nuclear-quadrupole coupling tensors are determined. These ENDOR results can be explained only by assuming a monovacancy model, i.e., O-2 replacing a single Cl- ion. The linewidth of the EPR signals is shown to be determined by the Rb SHF interaction. The corresponding powder ENDOR study of RbCl:O-2 is also presented. The powder ENDOR spectra could be simulated using the single-crystal data. Finally, from this simulation procedure a fitting program is derived to obtain information from powder ENDOR spectra of analogous systems.

  7. Nuclear Spin--Lattice Relaxation Study for 4f Electron State in CeT2Al10 (T = Ru, Os, and Fe): Comparison with RKKY System NdRu2Al10

    NASA Astrophysics Data System (ADS)

    Matsumura, Masahiro; Tomita, Naoya; Tanimoto, Sakiyo; Kawamura, Yukihiro; Kobayashi, Riki; Kato, Harukazu; Nishioka, Takashi; Tanida, Hiroshi; Sera, Masafumi

    2013-02-01

    In order to uncover the 4f electron state as a background for the emergence of the novel phase below T0 in CeT2Al10 (T = Ru, Os), the nuclear spin--lattice relaxation rate 1/T1 in the well-localized RKKY system NdRu2Al10 was measured and compared with that in CeRu2Al10. The value of 1/T1 in NdRu2Al10 with TN=2.4 K, which follows de Gennes scaling from TN=16 K in GdRu2Al10, shows a characteristic T-dependence for localized systems, 1/T1=a/(b+cT), with the constants a, b, and c. On the other hand, in CeRu2Al10, 1/T1 at temperatures higher than T*˜ 60 K also follows the same function if the Korringa relaxation is subtracted, indicating that the Ce 4f electron in CeRu2Al10 is in a localized state at least down to T*. Below the characteristic temperature T*, the downward deviation of 1/T1 from the above function might be ascribed to the beginning of Kondo coherence as proposed previously. Further comparison with CeT2Al10 compounds suggests that T* becomes more than 200 K in T = Os and that a coherent Kondo semiconducting state finally emerges in T = Fe.

  8. Unusual long-range spin-spin coupling in fluorinated polyenes: a mechanistic analysis.

    PubMed

    Gräfenstein, Jürgen; Cremer, Dieter

    2007-11-01

    Nuclear magnetic resonance (NMR) is a prospective means to realize quantum computers. The performance of a NMR quantum computer depends sensitively on the properties of the NMR-active molecule used, where one requirement is a large indirect spin-spin coupling over large distances. F-F spin-spin coupling constants (SSCCs) for fluorinated polyenes F-(CH==CH)n-F (n=1cdots, three dots, centered5) are >9 Hz across distances of more than 10 A. Analysis of the F,F spin-spin coupling mechanism with our recently developed decomposition of J into Orbital Contributions with the help of Orbital Currents and Partial Spin Polarization (J-OCOC-PSP=J-OC-PSP) method reveals that coupling is dominated by the spin-dipole (SD) term due to an interplay between the pi lone-pair orbitals at the F atoms and the pi(C2n) electron system. From our investigations we conclude that SD-dominated SSCCs should occur commonly in molecules with a contiguous pi-electron system between the two coupling nuclei and that a large SD coupling generally is the most prospective way to provide large long-range spin-spin coupling. Our results give guidelines for the design of suitable active molecules for NMR quantum computers. PMID:17994839

  9. Vibrational properties of the trinuclear spin crossover complex [Fe3(4-(2'-hydroxy-ethyl)-1,2,4-triazole)6(H2O)6](CF3SO3)6: a nuclear inelastic scattering, IR, Raman and DFT study.

    PubMed

    Wolny, Juliusz A; Rackwitz, Sergej; Achterhold, Klaus; Garcia, Yann; Muffler, Kai; Naik, Anil D; Schünemann, Volker

    2010-11-28

    The vibrational properties of the trimeric iron complex [Fe(3)(4-(2'-hydroxy-ethyl)-1,2,4-triazole)(6)(H(2)O)(6)](CF(3)SO(3))(6) which serves as a model of the 1D iron coordination polymers based on 1,2,4-triazoles have been investigated by nuclear inelastic scattering of synchrotron radiation (NIS), as well as by Raman and infrared (IR) spectroscopy. The system reveals a soft spin crossover involving only the central iron atom with its FeN(6) core, while the terminal FeN(3)O(3) units show no spin transition. The NIS spectra of the central low-spin isomer exhibit a number of marker bands in the 350-450 cm(-1) region which have not been detected in the Raman spectra. The density functional theory (DFT) calculations allowed the assignment of these bands to Fe-N bending and stretching modes. A characteristic high-spin marker mode has been identified and discriminated from the iron-ligand modes of the terminal iron atoms. This characteristic central Fe-N mode has been observed experimentally at 245 cm(-1) and theoretically at 255 cm(-1). Contrary to mononuclear centrosymmetric Fe complexes, some of the symmetric vibrations of the trimeric complex involving iron movements are observed by NIS. Furthermore the DFT calculations displayed the importance of the coulombic repulsion between metal ions for the geometry and stability of a given spin isomer. PMID:20931141

  10. Projective measurement in nuclear magnetic resonance

    E-print Network

    Jae-Seung Lee; A. K. Khitrin

    2006-05-02

    It is demonstrated that nuclear magnetic resonance experiments using pseudopure spin states can give possible outcomes of projective quantum measurement and probabilities of such outcomes. The physical system is a cluster of six dipolar-coupled nuclear spins of benzene in a liquid-crystalline matrix. For this system with the maximum total spin S=3, the results of measuring $S_X$ are presented for the cases when the state of the system is one of the eigenstates of $S_Z$.

  11. Optical polarization of nuclear ensembles in diamond

    E-print Network

    Ran Fischer; Andrey Jarmola; Pauli Kehayias; Dmitry Budker

    2013-01-21

    We report polarization of a dense nuclear-spin ensemble in diamond and its dependence on magnetic field and temperature. The polarization method is based on the transfer of electron spin polarization of negatively charged nitrogen vacancy color centers to the nuclear spins via the excited-state level anti-crossing of the center. We polarize 90% of the 14N nuclear spins within the NV centers, and 70% of the proximal 13C nuclear spins with hyperfine interaction strength of 13-14 MHz. Magnetic-field dependence of the polarization reveals sharp decrease in polarization at specific field values corresponding to cross-relaxation with substitutional nitrogen centers, while temperature dependence of the polarization reveals that high polarization persists down to 50 K. This work enables polarization of the 13C in bulk diamond, which is of interest in applications of nuclear magnetic resonance, in quantum memories of hybrid quantum devices, and in sensing.

  12. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2010-06-29

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  13. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2009-10-27

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  14. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2007-12-11

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  15. Spin microscope based on optically detected magnetic resonance

    DOEpatents

    Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

    2009-11-10

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  16. Visualization of an entangled channel spin-1 system

    SciTech Connect

    Sirsi, Swarnamala; Adiga, Veena [Department of Physics, Yuvaraja's College, University of Mysore, Mysore-05 (India)

    2010-08-15

    Covariance matrix formalism gives powerful entanglement criteria for continuous as well as finite dimensional systems. We use this formalism to study a mixed channel spin-1 system which is well known in nuclear reactions. A spin-j state can be visualized as being made up of 2j spinors which are represented by a constellation of 2j points on a Bloch sphere using Majorana construction. We extend this formalism to visualize an entangled mixed spin-1 system.

  17. Experimental Heat-Bath Cooling of Spins

    E-print Network

    Gilles Brassard; Yuval Elias; José M. Fernandez; Haggai Gilboa; Jonathan A. Jones; Tal Mor; Yossi Weinstein; Li Xiao

    2014-04-28

    Algorithmic cooling (AC) is a method to purify quantum systems, such as ensembles of nuclear spins, or cold atoms in an optical lattice. When applied to spins, AC produces ensembles of highly polarized spins, which enhance the signal strength in nuclear magnetic resonance (NMR). According to this cooling approach, spin-half nuclei in a constant magnetic field are considered as bits, or more precisely, quantum bits, in a known probability distribution. Algorithmic steps on these bits are then translated into specially designed NMR pulse sequences using common NMR quantum computation tools. The $algorithmic$ cooling of spins is achieved by alternately combining reversible, entropy-preserving manipulations (borrowed from data compression algorithms) with $selective$ $reset$, the transfer of entropy from selected spins to the environment. In theory, applying algorithmic cooling to sufficiently large spin systems may produce polarizations far beyond the limits due to conservation of Shannon entropy. Here, only selective reset steps are performed, hence we prefer to call this process "heat-bath" cooling, rather than algorithmic cooling. We experimentally implement here two consecutive steps of selective reset that transfer entropy from two selected spins to the environment. We performed such cooling experiments with commercially-available labeled molecules, on standard liquid-state NMR spectrometers. Our experiments yielded polarizations that $bypass$ $Shannon's$ $entropy$-$conservation$ $bound$, so that the entire spin-system was cooled. This paper was initially submitted in 2005, first to Science and then to PNAS, and includes additional results from subsequent years (e.g. for resubmission in 2007). The Postscriptum includes more details.

  18. Spin-Lattice Relaxation Times in 1H NMR Spectroscopy.

    ERIC Educational Resources Information Center

    Wink, Donald J.

    1989-01-01

    Discussed are the mechanisms of nuclear magnetic relaxation, and applications of relaxation times. The measurement of spin-lattice relaxations is reviewed. It is stressed that sophisticated techniques such as these are becoming more important to the working chemist. (CW)

  19. Subriemannian geodesics and optimal control of spin systems

    Microsoft Academic Search

    Navin Khaneja; Steffen Glaser; Roger Brockett

    2002-01-01

    Nuclear Magnetic Resonance (NMR) Spectroscopy in solution is an important modality for extracting structural information of macromolecules. In NMR spectroscopy, radio frequency electromagnetic pulses axe used to manipulate spin states of atomic nuclei. Pulse sequences that accomplish a desired spin control should be as short as possible in order to minimize the effects of thermal relaxation, and to optimize the

  20. Multiple-spin coherence transfer in linear Ising spin chains and beyond: numerically-optimized pulses and experiments

    Microsoft Academic Search

    Manoj Nimbalkar; Robert Zeier; Jorge L. Neves; S. Begam Elavarasi; Haidong Yuan; Navin Khaneja; Kavita Dorai; Steffen J. Glaser

    2011-01-01

    We study multiple-spin coherence transfers in linear Ising spin chains with nearest neighbor couplings. These constitute a model for efficient information transfers in future quantum computing devices and for many multi-dimensional experiments for the assignment of complex spectra in nuclear magnetic resonance spectroscopy. We complement prior analytic techniques for multiple-spin coherence transfers with a systematic numerical study where we obtain