Science.gov

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. Chemical and carbon-13 cross-polarization magic-angle spinning nuclear magnetic resonance characterization of logyard fines from British Columbia.

    PubMed

    Preston, C M; Forrester, P D

    2004-01-01

    Phasing out beehive burners and rising costs for landfilling have increased the need to widen options for utilization of the smaller size fractions of woody wastes generated during log handling and sawmilling in British Columbia. We characterized several size classes of logyard fines up to 16 mm sampled from coastal and interior operations. Total C, total N, ash, and condensed tannin concentrations were consistent with properties derived largely from wood, with varying proportions of bark and mixing with mineral soil. Especially for < 3-mm fractions, the latter resulted in high ash contents that would make them unsuitable for fuel. Solid-state 13C cross-polarization magic-angle spinning (CPMAS) nuclear magnetic resonance (NMR) spectra were consistent with the chemical data, with high O-alkyl intensity and similarity to naturally occurring woody forest floor; no samples were high in aromatic or phenolic C. Aqueous extracts of two < 16-mm fines, which accounted for only a small proportion of the total C, were enriched in alkyl C and had low or undetectable tannins. Application to forest sites might cause short-term immobilization of N, but also might include possible longer-term benefits from reduction of N loss after harvesting and restoration of soil organic matter in degraded sites. PMID:15074831

  3. Characterization of high-tannin fractions from humus by carbon-13 cross-polarization and magic-angle spinning nuclear magnetic resonance.

    PubMed

    Lorenz, Klaus; Preston, Caroline M

    2002-01-01

    Condensed tannins can be found in various parts of many plants. Unlike lignin there has been little study of their fate as they enter the soil organic matter pool and their influence on nutrient cycling, especially through their protein-binding properties. We extracted and characterized tannin-rich fractions from humus collected in 1998 from a black spruce [Picea mariana (Mill.) Britton et al.] forest in Canada where a previous study (1995) showed high levels (3.8% by weight) of condensed tannins. A reference tannin purified from black spruce needles was characterized by solution 13C nuclear magnetic resonance (NMR) as a pure procyanidin with mainly cis stereochemistry and an average chain length of four to five units. The colorimetric proanthocyanidin (PA) assay, standardized against the black spruce tannin, showed that both extracted humus fractions had higher tannin contents than the original humus (2.84% and 11.17% vs. 0.08%), and accounted for 32% of humus tannin content. Consistent with the results from the chemical assay, the aqueous fraction showed higher tannin signals in the 13C cross-polarization and magic-angle spinning (CPMAS) NMR spectrum than the emulsified one. As both tannin-rich humus fractions were depleted in N and high in structures derived from lignin and cutin, they did not have properties consistent with recaldtrant tannin-protein complexes proposed as a mechanism for N sequestration in humus. Further studies are needed to establish if tannin-protein structures in humus can be detected or isolated, or if tannins contribute to forest management problems observed in these ecosystems by binding to and slowing down the activity of soil enzymes. PMID:11931430

  4. Nuclear Magnetic Resonance Spectroscopy. Ring-Current Effects on Carbon-13 Chemical Shifts

    PubMed Central

    Vernet, Richard Du; Boekelheide, V.

    1974-01-01

    A comparison of the 13C nuclear magnetic resonance chemical shifts of some 15,16-dialkyl-15,16-dihydropyrenes with the corresponding 15,16-dialkyl-2,7,15,16-tetrahydropyrenes provides a measure of the effect of ring current on carbon-13 chemical shifts in which other effects may be expected to be negligibly small. The general conclusion is that the absolute magnitude of the ring-current effect is the same for carbon-13 as for protons when they occupy the same position in space relative to the aromatic ?-electron cloud. PMID:16578716

  5. Nuclear spin circular dichroism

    SciTech Connect

    Vaara, Juha; Rizzo, Antonio; Kauczor, Joanna; Norman, Patrick; Coriani, Sonia

    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.

  6. 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...

  7. 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.

  8. Natural abundance carbon 13 nuclear magnetic resonance spectroscopy of antifreeze glycoproteins

    SciTech Connect

    Berman, E.; Allerhand, A.; DeVries, A.L.

    1980-05-25

    Natural abundance /sup 13/C NMR spectroscopy (at 67.9 MHz) is used to study an aqueous solution of the antifreeze glycoproteins 3 to 6 from the Antarctic cod. Assignments of resonances to specific carbons of the known Ala-Ala-(..beta..Gal-(1 ..-->.. 3)-..cap alpha..-N-acetylgalactosamine)Thr repeating unit are presented. Some of the carbons of the proline residues of glycoprotein 6 are also identified. Spin-lattice relaxation times (at 30/sup 0/C), linewidths (at 35/sup 0/C), nuclear Overhauser enhancements (at 35/sup 0/C), and the temperature dependence of chemical shifts (from 0/sup 0/ to 75/sup 0/C) all strongly suggest that these antifreeze glycoproteins are predominantly or entirely flexible random coil polymers.

  9. 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.

  10. Characteristic spectral patterns in the carbon-13 nuclear magnetic resonance spectra of hexagonal and crenellated graphene fragments.

    PubMed

    zcan, Nergiz; Vhkangas, Jarkko; Lantto, Perttu; Vaara, Juha

    2014-06-23

    Nuclear magnetic resonance (NMR) spectroscopy is an important molecular characterisation method that may aid the synthesis and production of graphenes, especially the molecular-scale graphene nanoislands that have gathered significant attention due to their potential electronic and optical applications. Herein, carbon-13 NMR chemical shifts were calculated using density functional theory methods for finite, increasing-size fragments of graphene, hydrogenated graphene (graphane) and fluorinated graphene (fluorographene). Both concentric hexagon-shaped (zigzag boundary) and crenellated (armchair) fragments were investigated to gain information on the effect of different types of flake boundaries. Convergence trends of the (13)C chemical shift with respect to increasing fragment size and the boundary effects were found and rationalised in terms of low-lying electronically excited states. The results predict characteristic behaviour in the (13)C NMR spectra. Particular attention was paid to the features of the signals arising from the central carbon atoms of the fragments, for graphene and crenellated graphene on the one hand and graphane and fluorographene on the other hand, to aid the interpretation of the overall spectral characteristics. In graphene, the central nuclei become more shielded as the system size increases whereas the opposite behaviour is observed for graphane and fluorographene. The (13)C signals from some of the perimeter nuclei of the crenellated fragments obtain smaller and larger chemical shift values than central nuclei for graphene and graphane/fluorographene, respectively. The diameter of the graphenic quantum dots with zigzag boundary correlates well with the predicted carbon-13 chemical shift range, thus enabling estimation of the size of the system by NMR spectroscopy. The results provide data of predictive quality for future NMR analysis of the graphene nanoflake materials. PMID:24807480

  11. 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.

  12. Carbon-13 nuclear magnetic resonance study of metabolism of propionate by Escherichia coli.

    PubMed

    London, R E; Allen, D L; Gabel, S A; DeRose, E F

    1999-06-01

    We have evaluated the use of [1,2-13C2]propionate for the analysis of propionic acid metabolism, based on the ability to distinguish between the methylcitrate and methylmalonate pathways. Studies using propionate-adapted Escherichia coli MG1655 cells were performed. Preservation of the 13C-13C-12C carbon skeleton in labeled alanine and alanine-containing peptides involved in cell wall recycling is indicative of the direct formation of pyruvate from propionate via the methylcitrate cycle, the enzymes of which have recently been demonstrated in E. coli. Additionally, formation of 13C-labeled formate from pyruvate by the action of pyruvate-formate lyase is also consistent with the labeling of pyruvate C-1. Carboxylation of the labeled pyruvate leads to formation of [1,2-13C2]oxaloacetate and to multiply labeled glutamate and succinate isotopomers, also consistent with the flux through the methylcitrate pathway, followed by the tricarboxylic acid (TCA) cycle. Additional labeling of TCA intermediates arises due to the formation of [1-13C]acetyl coenzyme A from the labeled pyruvate, formed via pyruvate-formate lyase. Labeling patterns in trehalose and glycine are also interpreted in terms of the above pathways. The information derived from the [1, 2-13C2]propionate label is contrasted with information which can be derived from singly or triply labeled propionate and shown to be more useful for distinguishing the different propionate utilization pathways via nuclear magnetic resonance analysis. PMID:10348870

  13. A carbon-13 NMR spin-lattice relaxation study of the molecular conformation of the nootropic drug 2-oxopyrrolidin-1-ylacetamide

    NASA Astrophysics Data System (ADS)

    Baldo, M.; Grassi, A.; Guidoni, L.; Nicolini, M.; Pappalardo, G. C.; Viti, V.

    The spin-lattice relaxation times ( T1) of carbon-13 resonances of the drug 2-oxopyrrolidin- 1-ylacetamide ( 2OPYAC) were determined in CDCl 3 + DMSO and H 2O solutions to investigate the internal conformational flexibility. The measured T1s for the hydrogen-bearing carbon atoms of the 2-pyrrolidone ring fragment were diagnostic of a rigid conformation with respect to the acetamide linked moiety. The model of anisotropic reorientation of a rigid body was used to analyse the measured relaxation data in terms of a single conformation. Owing to the small number of T1 data available the fitting procedure for each of the possible conformations failed. The structure corresponding to the rigid conformation was therefore considered to be the one that is strongly stabilized by internal hydrogen bonding as predicted on the basis of theoretical MO ab initio quantum chemical calculations.

  14. A carbon-13 nuclear magnetic resonance study of the 3'-terminus of 16S ribosomal RNA of Escherichia coli specifically labeled with carbon-13 in the methylgroups of the m6(2)Am6(2)A sequence.

    PubMed

    Van Charldorp, R; Verhoeven, J J; Van Knippenberg, P H; Haasnoot, C A; Hilbers, C W

    1982-07-24

    30S ribosomes were isolated from a kasugamycin resistant mutant of E. coli that lacks methylgroups on two adjacent adenines in 16S ribosomal RNA. These ribosomes were methylated in vitro with a purified methylating enzyme and 5-S-adenosyl-(13C-methyl)-L-methionine chloride ((13C-methyl)-SAM) as methyldonor. After in situ cleavage of the 16S ribosomal RNA by the bacteriocin cloacin DF13, the 49 nucleotide fragment from the 3'-end of the RNA was isolated. The carbon-13 nuclear magnetic resonance spectra of the fragment at various temperatures were compared with those of 6-N-dimethyladenosine (m6(2)A) and 6-N-dimethyladenylyl-(3' leads to 5')-6-N-dimethyladenosine (m6(2)Am6(2)A). The data show that the two methylated adenines, which are part of a four membered hairpin loop, show a strong tendency to be stacked in analogy to the dinucleotide m6(2)Am6(2). PMID:6750555

  15. A carbon-13 nuclear magnetic resonance study of the 3'-terminus of 16S ribosomal RNA of Escherichia coli specifically labeled with carbon-13 in the methylgroups of the m6(2)Am6(2)A sequence.

    PubMed Central

    Van Charldorp, R; Verhoeven, J J; Van Knippenberg, P H; Haasnoot, C A; Hilbers, C W

    1982-01-01

    30S ribosomes were isolated from a kasugamycin resistant mutant of E. coli that lacks methylgroups on two adjacent adenines in 16S ribosomal RNA. These ribosomes were methylated in vitro with a purified methylating enzyme and 5-S-adenosyl-(13C-methyl)-L-methionine chloride ((13C-methyl)-SAM) as methyldonor. After in situ cleavage of the 16S ribosomal RNA by the bacteriocin cloacin DF13, the 49 nucleotide fragment from the 3'-end of the RNA was isolated. The carbon-13 nuclear magnetic resonance spectra of the fragment at various temperatures were compared with those of 6-N-dimethyladenosine (m6(2)A) and 6-N-dimethyladenylyl-(3' leads to 5')-6-N-dimethyladenosine (m6(2)Am6(2)A). The data show that the two methylated adenines, which are part of a four membered hairpin loop, show a strong tendency to be stacked in analogy to the dinucleotide m6(2)Am6(2). PMID:6750555

  16. 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.

  17. Nuclear spin noise imaging.

    PubMed

    Mller, Norbert; Jerschow, Alexej

    2006-05-01

    NMR images were obtained from the proton spin noise signals of a water-containing phantom, which was placed in the highly tuned, low-noise resonant circuit of a cryogenically cooled NMR probe in the presence of systematically varied magnetic field gradients. The spatially resolved proton spin density was obtained from the raw signal by a modified projection-reconstruction protocol. Although spin noise imaging is inherently less sensitive than conventional magnetic resonance imaging, it affords an entirely noninvasive visualization of the interior of opaque objects or subjects. Thus, tomography becomes possible even when neither x-ray nor radio frequency radiation can be applied for technical or safety reasons. PMID:16636281

  18. Detection of new temperature-dependent conformational transition in lysozyme by carbon-13 nuclear magnetic resonance spectroscopy.

    PubMed Central

    Cozzone, P J; Opella, S J; Jardetzky, O; Berthou, J; Jolls, P

    1975-01-01

    A specific temperature-dependent conformational transition of hen egg-white lysozyme, occurring between 20 degree C and 30 degree C in solution, has been detected by 13-C-nuclear magnetic resonance spectroscopy. Selective changes in the chemical shifts of aromatic residues, together with differences in the chemical shifts, and nuclear Overhauser enhancement in the carbonyl, carboxyl, and alpha-carbon regions of the spectrum point to the vicinity of subsites D and E as the primary locus of the structural change. PMID:1056017

  19. 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.

    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.

  20. 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)

  1. Molecular motions of [Beta]-carotene and a carotenoporphyrin dyad in solution. A carbon-13 NMR spin-lattice relaxation time study

    SciTech Connect

    Li, S.; Swindle, S.L.; Smith, S.K.; Nieman, R.A.; Moore, A.L.; Moore, T.A.; Gust, D. )

    1995-03-09

    Analysis of [sup 13]C NMR spin-lattice relaxation times (T[sub 1]) yields information concerning both overall tumbling of molecules in solution and internal rotations about single bonds. Relaxation time and nuclear Overhauser effect data have been obtained for [Beta]-carotene and two related molecules, squalane and squalene, for zinc meso-tetraphenylporphyrin, and for a dyad consisting of a porphyrin covalently linked to a carotenoid polyene through a trimethylene bridge. Squalane and squalene, which lack conjugated double bonds, behave essentially as limp string, with internal rotations at least as rapid as overall isotropic tumbling motions. In contrast, [Beta]-carotene reorients as a rigid rod, with internal motions which are too slow to affect relaxation times. Modeling it as an anisotropic rotor yields a rotational diffusion coefficient for motion about the major axis which is 14 times larger than that for rotation about axes perpendicular to that axis. The porphyrin reorients more nearly isotropically and features internal librational motions about the single bonds to the phenyl groups. The relaxation time data for the carotenoporphyrin are consistent with internal motions similar to those of a medieval military flail. 31 refs., 3 figs., 5 tabs.

  2. Control of electron spin decoherence in nuclear spin baths

    NASA Astrophysics Data System (ADS)

    Liu, Ren-Bao

    2011-03-01

    Nuclear spin baths are a main mechanism of decoherence of spin qubits in solid-state systems, such as quantum dots and nitrogen-vacancy (NV) centers of diamond. The decoherence results from entanglement between the electron and nuclear spins, established by quantum evolution of the bath conditioned on the electron spin state. When the electron spin is flipped, the conditional bath evolution is manipulated. Such manipulation of bath through control of the electron spin not only leads to preservation of the center spin coherence but also demonstrates quantum nature of the bath. In an NV center system, the electron spin effectively interacts with hundreds of 13 C nuclear spins. Under repeated flip control (dynamical decoupling), the electron spin coherence can be preserved for a long time (> 1 ms) . Thereforesomecharacteristicoscillations , duetocouplingtoabonded 13 C nuclear spin pair (a dimer), are imprinted on the electron spin coherence profile, which are very sensitive to the position and orientation of the dimer. With such finger-print oscillations, a dimer can be uniquely identified. Thus, we propose magnetometry with single-nucleus sensitivity and atomic resolution, using NV center spin coherence to identify single molecules. Through the center spin coherence, we could also explore the many-body physics in an interacting spin bath. The information of elementary excitations and many-body correlations can be extracted from the center spin coherence under many-pulse dynamical decoupling control. Another application of the preserved spin coherence is identifying quantumness of a spin bath through the back-action of the electron spin to the bath. We show that the multiple transition of an NV center in a nuclear spin bath can have longer coherence time than the single transition does, when the classical noises due to inhomogeneous broadening is removed by spin echo. This counter-intuitive result unambiguously demonstrates the quantumness of the nuclear spin bath. This work was supported by Hong Kong RGC/GRF CUHK402207, CUHK402209, and CUHK402410. The author acknowledges collaboration with Nan Zhao, Jian-Liang Hu, Sai Wah Ho, Jones T. K. Wan, and Jiangfeng Du.

  3. STM NMR and nuclear spin noise

    NASA Astrophysics Data System (ADS)

    Balatsky, A. V.; Fransson, J.; Mozyrsky, D.; Manassen, Yishay

    2006-05-01

    Fluctuations of an electronic spin can be revealed in the tunneling current fluctuations of a scanning tunneling microscope (STM). We consider fluctuations of the electronic spin due to coupling to nuclear spin. We argue that the noise spectroscopy of electronic spin can reveal the nuclear spin dynamics due to hyperfine coupling. We find that the STM tunneling current power spectrum develops hyperfine split satellites of the main lines at Larmor frequency and at zero frequency. We also address the role of the rf field that is at or near the resonance with the nuclear hyperfine field. This approach is similar to electron nuclear double resonance in that is allows one to detect nuclear spin dynamics indirectly through its effect on electronic spin.

  4. A Short Set of Carbon 13-NMR Correlation Tables.

    ERIC Educational Resources Information Center

    Brown, D. W.

    1985-01-01

    Presents a short set of carbon-13 nuclear magnetic resonance (NMR) tables. These tables not only serve pedagogic purposes but also allow students to do calculations rapidly and with acceptable accuracy for a wide variety of compounds. (JN)

  5. Molecular determinants for drug-receptor interactions. 8. Anisotropic and internal motions in morphine, nalorphine, oxymorphone, naloxone and naltrexone in aqueous solution by carbon-13 NMR spin-lattice relaxation times

    NASA Astrophysics Data System (ADS)

    Grassi, Antonio; Perly, Bruno; Pappalardo, Giuseppe C.

    1989-02-01

    Carbon-13 NMR spin-lattice relaxation times ( T1) were measured for morphine, oxymorphone, nalorphine, naloxone and naltrexone as hydrochloride salts in 2H 2O solution. The data refer to the molecules in the N-equatorial configuration. The experimental T1 values were interpreted using a model of anisotropic reorientation of a rigid body with superimposed internal motions of the flexible N-methyl, N-methyl-allyl and N-methyl-cyclopropyl fragments. The calculated internal motional rates were found to markedly decrease on passing from agonists to mixed (nalorphine) and pure (naloxone, naltrexone) antagonists. For these latter the observed trend of the internal flexibility about NC and CC bonds of the N-substituents is discussed in terms of a correlation with their relative antagonistic potencies. In fact, such an evidence of decreasing internal conformational dynamics in the order nalorphine, naloxone, naltrexone, appeared interestingly in line with the "two-state" model of opiate receptor operation mode proposed by Snyder.

  6. Carbon distribution in coals and coal macerals by cross polarization magic angle spinning carbon-13 nuclear magnetic resonance spectrometry

    SciTech Connect

    Wilson, M.A.; Pugmire, R.J.; Karas, J.; Alemany, L.B.; Woolfenden, W.R.; Grant, D.M.; Given, P.H.

    1984-01-01

    Conventional and dipolar dephasing CP/MAS /sup 13/C NMR experiments are reported on 63 coals and coal macerals from lignite to anthracite ranks (from the US, the United Kingdom, and Australia). While the conventional experiment can yield only f/sub a/ (the fraction of carbon that is sp/sub 2/ hybridized), the dipolar dephasing experiments provide estimates of four other structural parameters. Examination of the dipolar dephasing data reveals an overall increase. While loss of substituents from aromatic rings with little aromatic cross-linking occurs until the anthracite stage is reached, the dipolar dephasing experiments also yield decay constants for different functional groups that are similar to the decay constants obtained with simple organic compounds. Because full characterization of a sample by the dipolar approach has been developed for obtaining less precise f/sub a/sup a,H/, f/sub a/sup H/, f/sub Me/, and H/sub a/ values. The data so obtained are particularly useful for quickly comparing samples. 43 references, 7 tables, 9 figures.

  7. Nuclear spin conversion in diatomic molecules

    SciTech Connect

    Il'ichev, L. V. Shalagin, A. M.

    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})

  8. Liquid-state nuclear spin comagnetometers.

    PubMed

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

    2012-06-15

    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 19F 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 510(-9)??Hz, or about 510(-11)??Hz in ?1 day of integration. In a second version, spin precession of protons and 129Xe 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. PMID:23004267

  9. Detection and Control of Individual Nuclear Spins Using a Weakly Coupled Electron Spin

    SciTech Connect

    Taminiau, T.H.; Wagenaar, J.J.T.; van der Sar, T.; Jelezko, F.; Dobrovitski, Viatcheslav V.; Hanson, R.

    2012-09-28

    We experimentally isolate, characterize, and coherently control up to six individual nuclear spins that are weakly coupled to an electron spin in diamond. Our method employs multipulse sequences on the electron spin that resonantly amplify the interaction with a selected nuclear spin and at the same time dynamically suppress decoherence caused by the rest of the spin bath. We are able to address nuclear spins with interaction strengths that are an order of magnitude smaller than the electron spin dephasing rate. Our results provide a route towards tomography with single-nuclear-spin sensitivity and greatly extend the number of available quantum bits for quantum information processing in diamond.

  10. 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.

  11. Dynamic Nuclear Polarization by Electrical Spin Injection

    NASA Astrophysics Data System (ADS)

    Strand, Jonathan

    2004-03-01

    The hyperfine coupling between electrons and nuclei in GaAs can give rise to dynamic nuclear polarization (DNP) and plays an important role in many proposed spintronic devices. We have demonstrated that DNP can be driven by a spin-polarized current injected from Fe into a GaAs quantum well (QW). The samples are Schottky spin-LEDs in which a Fe contact is a source of spin-polarized electrons and a QW serves as a spin detector. Measurements are performed in a low magnetic field (<1 kOe) applied in the plane of the QW. In this geometry the QW electroluminescence polarization (ELP) is sensitive only to the component of the spin that precesses out of the QW plane after injection into the GaAs. We find that the precession frequency depends on both the applied field and a hyperfine field (B_N) due to polarized nuclei. The data are described by modeling the electron spin dynamics while incorporating the magnetocrystalline anisotropy of the Fe contact, spin relaxation in the QW, and an effective BN up to 1 T [1]. BN increases with increasing current density before saturating at current densities 10 A/cm^2. The DNP decreases with increasing temperature and is not detected above 80 K. Explicit signatures of DNP are observed via the time dependence of the ELP and resonant depolarization of nuclei by a time-dependent magnetic field (H_1) [2]. BN builds up exponentially with characteristic times of 20-45 seconds and persists for several minutes after the spin-polarized current is turned off. This approach to spin injection realizes the possibility of using DC electrical currents to inject and manipulate spin-polarized carriers in a semiconductor device. [1] J. Strand, et al., Phys. Rev. Lett. 91, 036602 (2003); [2] Appl. Phys. Lett. 83, 3335 (2003).

  12. Nuclear moment of inertia and spin distribution of nuclear levels

    SciTech Connect

    Alhassid, Y.; Fang, L.; Liu, S.; Bertsch, G.F.

    2005-12-15

    We introduce a simple model to calculate the nuclear moment of inertia at finite temperature. This moment of inertia describes the spin distribution of nuclear levels in the framework of the spin-cutoff model. Our model is based on a deformed single-particle Hamiltonian with pairing interaction and takes into account fluctuations in the pairing gap. We derive a formula for the moment of inertia at finite temperature that generalizes the Belyaev formula for zero temperature. We show that a number-parity projection explains the strong odd-even effects observed in shell model Monte Carlo studies of the nuclear moment of inertia in the iron region.

  13. 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

    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.

  14. 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; Hgele, 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.

  15. 29Si nuclear spins as a resource for donor spin qubits in silicon

    NASA Astrophysics Data System (ADS)

    Wolfowicz, Gary; Mortemousque, Pierre-André; Guichard, Roland; Simmons, Stephanie; Thewalt, Mike L. W.; Itoh, Kohei M.; Morton, John J. L.

    2016-02-01

    Nuclear spin registers in the vicinity of electron spins in solid state systems offer a powerful resource to address the challenge of scalability in quantum architectures. We investigate here the properties of 29Si nuclear spins surrounding donor atoms in silicon, and consider the use of such spins, combined with the donor nuclear spin, as a quantum register coupled to the donor electron spin. We find the coherence of the nearby 29Si nuclear spins is effectively protected by the presence of the donor electron spin, leading to coherence times in the second timescale—over two orders of magnitude greater than the coherence times in bulk silicon. We theoretically investigate the use of such a register for quantum error correction (QEC), including methods to protect nuclear spins from the ionisation/neutralisation of the donor, which is necessary for the re-initialisation of the ancillae qubits. This provides a route for multi-round QEC using donors in silicon.

  16. Nuclear spin squeezing via electric quadrupole interaction

    NASA Astrophysics Data System (ADS)

    Aksu Korkmaz, Ya?mur; Bulutay, Ceyhun

    2016-01-01

    Control over nuclear-spin fluctuations is essential for processes that rely on preserving the quantum state of an embedded system. For this purpose, squeezing is a viable alternative, so far that has not been properly exploited for the nuclear spins. Of particular relevance in solids is the electric quadrupole interaction (QI), which operates on nuclei having spin higher than 1/2. In its general form, QI involves an electric-field gradient (EFG) biaxiality term. Here, we show that as this EFG biaxiality increases, it enables continuous tuning of single-particle squeezing from the one-axis twisting to the two-axis countertwisting limits. A detailed analysis of QI squeezing is provided, exhibiting the intricate consequences of EFG biaxiality. The initial states over the Bloch sphere are mapped out to identify those favorable for fast initial squeezing, or for prolonged squeezings. Furthermore, the evolution of squeezing in the presence of a phase-damping channel and an external magnetic field are investigated. We observe that dephasing drives toward an antisqueezed terminal state, the degree of which increases with the spin angular momentum. Finally, QI squeezing in the limiting case of a two-dimensional EFG with a perpendicular magnetic field is discussed, which is of importance for two-dimensional materials, and the associated beat patterns in squeezing are revealed.

  17. Electron spin decoherence by interacting nuclear spins in quantum dot II: Coherent control

    NASA Astrophysics Data System (ADS)

    Liu, Ren-Bao; Yao, Wang; Sham, Lu J.

    2006-03-01

    Due to the hyperfine interaction, the nuclear spins in a quantum dot, driven by nuclear spin pair-wise flip-flops, evolve in different pathways in the Hilbert space for different electron spin states, resulting in the electron-nuclei entanglement and hence the electron spin decoherence. When the electron spin is flipped by a pulse, the nuclear spin states for different electron spin states swap their pathways, and could intersect in the Hilbert space, which disentangles the electron and the nuclei and hence restores the electron spin coherence. The coherence restoration by disentanglement and the conventional spin echo in ensemble dynamics are fundamentally different and generally occur at different time. Pulse sequences can be applied to force the disentanglement to coincide with the spin echo, making the coherence recovery observable in ensemble dynamics. This work was supported by NSF DMR-0403465, NSA/ARO, and DARPA/AFOSR.

  18. Impact of nuclear spin dynamics on electron transport through donors

    NASA Astrophysics Data System (ADS)

    Gorman, S. K.; Broome, M. A.; Baker, W. J.; Simmons, M. Y.

    2015-09-01

    We present an analysis of electron transport through two weakly coupled precision-placed phosphorus donors in silicon. In particular, we examine the (1,1)?(0,2) charge transition where we predict a type of current blockade driven entirely by the nuclear spin dynamics. Using this nuclear spin blockade mechanism, we devise a protocol to read out the state of single nuclear spins using electron-transport measurements only. We extend our model to include realistic effects such as Stark shifted hyperfine interactions and multidonor clusters. In the case of multidonor clusters we show how nuclear spin blockade can be alleviated, allowing for low magnetic field electron-spin measurements.

  19. Origin of the Cytoplasmic pH Changes during Anaerobic Stress in Higher Plant Cells. Carbon-13 and Phosphorous-31 Nuclear Magnetic Resonance Studies

    PubMed Central

    Gout, Elisabeth; Boisson, Anne-Marie; Aubert, Serge; Douce, Roland; Bligny, Richard

    2001-01-01

    We tested the contribution of nucleoside triphosphate (NTP) hydrolysis, ethanol, and organic acid syntheses, and H+-pump ATPases activity in the acidosis of anoxic sycamore (Acer pseudoplatanus) plant cells. Culture cells were chosen to alter NTP pools and fermentation with specific nutrient media (phosphate [Pi]-deprived and adenine- or glycerol-supplied). In vivo 31P- and 13C-nuclear magnetic resonance (NMR) spectroscopy was utilized to noninvasively measure intracellular pHs, Pi, phosphomonoesters, nucleotides, lactate, and ethanol. Following the onset of anoxia, cytoplasmic (cyt) pH (7.5) decreased to 6.8 within 4 to 5 min, whereas vacuolar pH (5.7) and external pH (6.5) remained stable. The NTP pool simultaneously decreased from 210 to <20 nmol g−1 cell wet weight, whereas nuceloside diphosphate, nucleoside monophosphate, and cyt pH increased correspondingly. The initial cytoplasmic acidification was at a minimum in Pi-deprived cells containing little NTP, and at a maximum in adenine-incubated cells showing the highest NTP concentration. Our data show that the release of H+ ions accompanying the Pi-liberating hydrolysis of NTP was the principal cause of the initial cyt pH drop and that this cytoplasmic acidosis was not overcome by H+ extrusion. After 15 min of anoxia, a partial cyt-pH recovery observed in cells supplied with Glc, but not with glycerol, was attributed to the H+-consuming ATP synthesis accompanying ethanolic fermentation. Following re-oxygenation, the cyt pH recovered its initial value (7.5) within 2 to 3 min, whereas external pH decreased abruptly. We suggest that the H+-pumping ATPase located in the plasma membrane was blocked in anoxia and quickly reactivated after re-oxygenation. PMID:11161048

  20. 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

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    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.

  2. Coherent manipulation of single electronic and nuclear spins in diamond

    NASA Astrophysics Data System (ADS)

    Childress, Lilian

    2008-05-01

    The complex environment of solid-state systems poses a central challenge for solid-state realizations of quantum bits. Nevertheless, we show that the solid-state environment of a single spin can be understood, controlled, and even utilized as a resource. Using coherent manipulation of a single electronic spin associated with a nitrogen-vacancy (NV) center in diamond, we probe the ^13C nuclear spin bath formed by impurities in the surrounding diamond lattice. We show that this environment is effectively separated into a set of individual, proximal ^13C nuclear spins which are coupled coherently to the electron spin, and the remainder of the ^13C nuclear spins, which cause the loss of coherence. By manipulating the NV center via microwave and optical excitation, we demonstrate robust, room-temperature initialization of the two-qubit register formed by the electronic spin and the nearest-neighbor ^13C nuclear spin. Within this register, arbitrary quantum states can be transferred between the electronic and nuclear spin, while the nuclear spin qubit can be well isolated from the electron spin, even during optical polarization and measurement of the electronic state. Finally, we observe coherent interactions between individual nuclear spins, and demonstrate that they have excellent coherence properties, approaching those of isolated atoms and ions. Combined with teleportation-based quantum gates, such registers offer a basis for scalable, optically coupled quantum information systems.

  3. Dynamic nuclear spin resonance in n-GaAs.

    PubMed

    Chen, Y S; Reuter, D; Wieck, A D; Bacher, G

    2011-10-14

    The dynamics of optically detected nuclear magnetic resonance is studied in n-GaAs via time-resolved Kerr rotation using an on-chip microcoil for rf field generation. Both optically allowed and optically forbidden NMR are observed with a dynamics controlled by the interplay between dynamic nuclear polarization via hyperfine interaction with optically generated spin-polarized electrons and nuclear spin depolarization due to magnetic resonance absorption. Comparing the characteristic nuclear spin relaxation rate obtained in experiment with master equation simulations, the underlying nuclear spin depolarization mechanism for each resonance is extracted. PMID:22107431

  4. Detection and manipulation of nuclear spin states in fermionic strontium

    SciTech Connect

    Stellmer, Simon; Grimm, Rudolf; Schreck, Florian

    2011-10-15

    Fermionic {sup 87}Sr has a nuclear spin of I=9/2, higher than any other element with a similar electronic structure. This large nuclear spin has many applications in quantum simulation and computation, for which preparation and detection of the spin state are requirements. For an ultracold {sup 87}Sr cloud, we show two complementary methods to characterize the spin-state mixture: optical Stern-Gerlach state separation and state-selective absorption imaging. We use these methods to optimize the preparation of a variety of spin-state mixtures by optical pumping and to measure an upper bound of the {sup 87}Sr spin-relaxation rate.

  5. Detection and manipulation of nuclear spin states in fermionic strontium

    NASA Astrophysics Data System (ADS)

    Stellmer, Simon; Grimm, Rudolf; Schreck, Florian

    2011-10-01

    Fermionic 87Sr has a nuclear spin of I=9/2, higher than any other element with a similar electronic structure. This large nuclear spin has many applications in quantum simulation and computation, for which preparation and detection of the spin state are requirements. For an ultracold 87Sr cloud, we show two complementary methods to characterize the spin-state mixture: optical Stern-Gerlach state separation and state-selective absorption imaging. We use these methods to optimize the preparation of a variety of spin-state mixtures by optical pumping and to measure an upper bound of the 87Sr spin-relaxation rate.

  6. Detecting and Polarizing Nuclear Spins with Double Resonance on a Single Electron Spin

    NASA Astrophysics Data System (ADS)

    London, P.; Scheuer, J.; Cai, J.-M.; Schwarz, I.; Retzker, A.; Plenio, M. B.; Katagiri, M.; Teraji, T.; Koizumi, S.; Isoya, J.; Fischer, R.; McGuinness, L. P.; Naydenov, B.; Jelezko, F.

    2013-08-01

    We report the detection and polarization of nuclear spins in diamond at room temperature by using a single nitrogen-vacancy (NV) center. We use Hartmann-Hahn double resonance to coherently enhance the signal from a single nuclear spin while decoupling from the noisy spin bath, which otherwise limits the detection sensitivity. As a proof of principle, we (i) observe coherent oscillations between the NV center and a weakly coupled nuclear spin and (ii) demonstrate nuclear-bath cooling, which prolongs the coherence time of the NV sensor by more than a factor of 5. Our results provide a route to nanometer scale magnetic resonance imaging and novel quantum information processing protocols.

  7. Inelastic electron tunneling spectroscopy of a single nuclear spin.

    PubMed

    Delgado, F; Fernndez-Rossier, J

    2011-08-12

    Detection of a single nuclear spin constitutes an outstanding problem in different fields of physics such as quantum computing or magnetic imaging. Here we show that the energy levels of a single nuclear spin can be measured by means of inelastic electron tunneling spectroscopy (IETS). We consider two different systems, a magnetic adatom probed with scanning tunneling microscopy and a single Bi dopant in a silicon nanotransistor. We find that the hyperfine coupling opens new transport channels which can be resolved at experimentally accessible temperatures. Our simulations evince that IETS yields information about the occupations of the nuclear spin states, paving the way towards transport-detected single nuclear spin resonance. PMID:21902416

  8. Nuclear-spin optical rotation in xenon

    NASA Astrophysics Data System (ADS)

    Savukov, I.

    2015-10-01

    The nuclear-spin optical rotation (NSOR) effect, which has potential applications in correlated nuclear-spin-resonance optical spectroscopy, has previously been explored experimentally and theoretically in liquid Xe. Calculations of the Xe NSOR constant are very challenging because the result is sensitive to correlations, relativistic effects, and the choice of basis, with strong cancellation between contributions from lowest and remaining states. The relativistic configuration-interaction many-body-theory approach, presented here, is promising because this approach has been successful in predicting various properties of noble-gas atoms, such as energies, oscillator strengths (OSs), Verdet constants, and photoionization cross sections. However, correlations become stronger along the sequence of noble-gas atoms and the theoretical accuracy in Xe is not as high as, for example, in neon and argon. To improve the accuracy of the Xe Verdet and NSOR constants, which are calculated as explicit sums over the excited states, theoretical values for the several lowest levels are replaced with empirical values of energies, OSs, and hyperfine structure constants. We found that the Xe Verdet constant is in excellent agreement with accurate measurements. To take into account liquid effects, empirical data for energy shifts were also used to correct the NSOR constant. The resulting Xe NSOR constant is in a good agreement with experiment, although the liquid-state effect is treated quite approximately.

  9. 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.

  10. Time-optimal polarization transfer from an electron spin to a nuclear spin

    NASA Astrophysics Data System (ADS)

    Yuan, Haidong; Zeier, Robert; Pomplun, Nikolas; Glaser, Steffen J.; Khaneja, Navin

    2015-11-01

    Polarization transfers from an electron spin to a nuclear spin are essential for various physical tasks, such as dynamic nuclear polarization in nuclear magnetic resonance and quantum information processing on hybrid electron-nuclear spin systems. We present time-optimal schemes for electron-nuclear polarization transfers which improve on conventional approaches, and we thereby establish an important class of faster controls. We highlight how time-optimal polarization transfers and their optimality are related to the time optimality of unitary transformations. Moreover, our work develops generally applicable analytic methods for analyzing the limits in controlling quantum systems.

  11. Self-quenching of nuclear spin dynamics in the central spin problem

    NASA Astrophysics Data System (ADS)

    Brataas, Arne; Rashba, Emmanuel I.

    2014-01-01

    We consider, in the framework of the central spin s =1/2 model, driven dynamics of two electrons in a double quantum dot subject to hyperfine interaction with nuclear spins and spin-orbit coupling. The nuclear subsystem dynamically evolves in response to Landau-Zener singlet-triplet transitions of the electronic subsystem controlled by external gate voltages. Without noise and spin-orbit coupling, subsequent Landau-Zener transitions die out after about 104 sweeps, the system self-quenches, and nuclear spins reach one of the numerous glassy dark states. We present an analytical model that captures this phenomenon. We also account for the multi-nuclear-specie content of the dots and numerically determine the evolution of around 107 nuclear spins in up to 2105 Landau-Zener transitions. Without spin-orbit coupling, self-quenching is robust and sets in for arbitrary ratios of the nuclear spin precession times and the waiting time between Landau-Zener sweeps as well as under moderate noise. In the presence of spin-orbit coupling of a moderate magnitude, and when the waiting time is in resonance with the precession time of one of the nuclear species, the dynamical evolution of nuclear polarization results in stroboscopic screening of spin-orbit coupling. However, small deviations from the resonance or strong spin-orbit coupling destroy this screening. We suggest that the success of the feedback loop technique for building nuclear gradients is based on the effect of spin-orbit coupling.

  12. 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-Ladrire, M.; Lu, H.; Palmstrm, 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.

  13. 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.

  14. Optically induced dynamic nuclear spin polarisation in diamond

    NASA Astrophysics Data System (ADS)

    Scheuer, Jochen; Schwartz, Ilai; Chen, Qiong; Schulze-Sünninghausen, David; Carl, Patrick; Höfer, Peter; Retzker, Alexander; Sumiya, Hitoshi; Isoya, Junichi; Luy, Burkhard; Plenio, Martin B.; Naydenov, Boris; Jelezko, Fedor

    2016-01-01

    The sensitivity of magnetic resonance imaging (MRI) depends strongly on nuclear spin polarisation and, motivated by this observation, dynamical nuclear spin polarisation has recently been applied to enhance MRI protocols (Kurhanewicz et al 2011 Neoplasia 13 81). Nuclear spins associated with the 13C carbon isotope (nuclear spin I = 1/2) in diamond possess uniquely long spin lattice relaxation times (Reynhardt and High 2011 Prog. Nucl. Magn. Reson. Spectrosc. 38 37). If they are present in diamond nanocrystals, especially when strongly polarised, they form a promising contrast agent for MRI. Current schemes for achieving nuclear polarisation, however, require cryogenic temperatures. Here we demonstrate an efficient scheme that realises optically induced 13C nuclear spin hyperpolarisation in diamond at room temperature and low ambient magnetic field. Optical pumping of a nitrogen-vacancy centre creates a continuously renewable electron spin polarisation which can be transferred to surrounding 13C nuclear spins. Importantly for future applications we also realise polarisation protocols that are robust against an unknown misalignment between magnetic field and crystal axis.

  15. 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

  16. Nuclear Spin Conversion in CH4: A Multichannel Relaxation Mechanism.

    PubMed

    Cacciani, Patrice; Coslou, Jean; Khelkhal, Mohamed; ?ermk, Peter; Puzzarini, Cristina

    2016-01-21

    Experiments on nuclear spin interconversion of ortho, para, and meta nuclear spin isomers of the methane molecule have been undertaken in gas phase and cryomatrices. Only the latter environment has led to the observation of the nuclear spin conversion. In this study, a quantitative explanation is given for the first time by considering the coupling of three relaxation paths: meta ? para, meta ? ortho, and ortho ? para. The global evolution of the three populations of spin isomers is thus described by two characteristic times, which have been calculated using the best values of the energy levels for the vibrational ground state, of the intramolecular magnetic interactions, and of the collisional relaxation rates, and for different pressure and temperature conditions. Such calculations also provide an indication for the proper choice of reliable scenarios for experimental separation of the spin isomers of methane. PMID:26681482

  17. Electronic read-out of a single nuclear spin using a molecular spin transistor

    NASA Astrophysics Data System (ADS)

    Balestro, Franck

    2013-03-01

    Thanks to recent advances of nanofabrication techniques, molecular electronics devices can address today the ultimate probing of electronic transport flowing through a single molecule. Not only this electronic current can show signatures of the molecular quantum levels but it can also detect the magnetic state of the molecule. As a consequence, an entirely novel research field called molecular spintronics in which quantum magnetism of molecular systems can be interfaced to nanoelectronics is now emerging. One of the recent challenges of this field was to probe by this current, not the only spin state of an electron, but the state of a single nuclear spin. Such an achievement was experimentally unimaginable a few years ago. Indeed, the magnetic signal carried by a single nuclear spin is a thousand times less than that of a single electron spin... Using a Single Molecular Magnet (TbPc2) as a molecular spin transistor in a three terminals configuration, the experiment consists in measuring the current changes when ones sweep the external magnetic field applied to the molecule. When the magnetic spin of the molecule changes its quantum state, a change of current is recorded. Because of the well-defined relationship that exists between the electron spin and nuclear spin carried by the nuclei of the Terbium atom, it is possible to perform the electronic read-out of the electronic spin state which, in turn give information on the state of a single nuclear spin. Application of this effect for quantum information manipulation and storage can be envisioned, as the observation of energy level lifetimes on the order of tens of seconds opens the way to coherent manipulations of a single nuclear spin. In collaboration with R. Vincent, Neel Institut - CNRS - UJF; S. Klyatskaya, Institut of Nanotechnology - KIT; M. Ruben, Institut of Nanotechnology - KIT; and W. Wernsdorfer, Neel Institut - CNRS - UJF.

  18. Polarization of nuclear spins by a cold nanoscale resonator

    NASA Astrophysics Data System (ADS)

    Butler, Mark C.; Weitekamp, Daniel P.

    2011-12-01

    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/R0, where R0 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 R0. 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.

  19. Nuclear spin content and constraints on exotic spin-dependent couplings

    NASA Astrophysics Data System (ADS)

    Kimball, D. F. Jackson

    2015-07-01

    There are numerous recent and ongoing experiments employing a variety of atomic species to search for couplings of atomic spins to exotic fields. In order to meaningfully compare these experimental results, the coupling of the exotic field to the atomic spin must be interpreted in terms of the coupling to electron, proton, and neutron spins. Traditionally, constraints from atomic experiments on exotic couplings to neutron and proton spins have been derived using the single-particle Schmidt model for nuclear spin. In this model, particular atomic species are sensitive to either neutron or proton spin couplings, but not both. More recently, semi-empirical models employing nuclear magnetic moment data have been used to derive new constraints for non-valence nucleons. However, comparison of such semi-empirical models to detailed large-scale nuclear shell model calculations and analysis of known physical effects in nuclei show that existing semi-empirical models cannot reliably be used to predict the spin polarization of non-valence nucleons. The results of our re-analysis of nuclear spin content are applied to searches for exotic long-range monopole-dipole and dipole-dipole couplings of nuclei leading to significant revisions of some published constraints.

  20. Detecting and polarizing nuclear spins with double resonance on a single electron spin.

    PubMed

    London, P; Scheuer, J; Cai, J-M; Schwarz, I; Retzker, A; Plenio, M B; Katagiri, M; Teraji, T; Koizumi, S; Isoya, J; Fischer, R; McGuinness, L P; Naydenov, B; Jelezko, F

    2013-08-01

    We report the detection and polarization of nuclear spins in diamond at room temperature by using a single nitrogen-vacancy (NV) center. We use Hartmann-Hahn double resonance to coherently enhance the signal from a single nuclear spin while decoupling from the noisy spin bath, which otherwise limits the detection sensitivity. As a proof of principle, we (i)observe coherent oscillations between the NV center and a weakly coupled nuclear spin and (ii)demonstrate nuclear-bath cooling, which prolongs the coherence time of the NV sensor by more than a factor of 5. Our results provide a route to nanometer scale magnetic resonance imaging and novel quantum information processing protocols. PMID:23971612

  1. Nuclear magnetic resonance spectroscopy with single spin sensitivity.

    PubMed

    Mller, 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 (29)Si 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

  2. Robust dynamical decoupling sequences for individual-nuclear-spin addressing

    NASA Astrophysics Data System (ADS)

    Casanova, J.; Wang, Z.-Y.; Haase, J. F.; Plenio, M. B.

    2015-10-01

    We propose the use of non-equally-spaced decoupling pulses for high-resolution selective addressing of nuclear spins by a quantum sensor. The analytical model of the basic operating principle is supplemented by detailed numerical studies that demonstrate the high degree of selectivity and the robustness against static and dynamic control-field errors of this scheme. We exemplify our protocol with a nitrogen-vacancy-center-based sensor to demonstrate that it enables the identification of individual nuclear spins that form part of a large spin ensemble.

  3. Highly selective detection of individual nuclear spins with rotary echo on an electron spin probe

    DOE PAGESBeta

    Mkhitaryan, V. V.; Jelezko, F.; Dobrovitski, V. V.

    2015-10-26

    We consider an electronic spin, such as a nitrogen-vacancy center in diamond, weakly coupled to a large number of nuclear spins, and subjected to the Rabi driving with a periodically alternating phase. We show that by switching the driving phase synchronously with the precession of a given nuclear spin, the interaction to this spin is selectively enhanced, while the rest of the bath remains decoupled. The enhancement is of resonant character. The key feature of the suggested scheme is that the width of the resonance is adjustable, and can be greatly decreased by increasing the driving strength. Thus, the resonancemore » can be significantly narrowed, by a factor of 10–100 in comparison with the existing detection methods. Significant improvement in selectivity is explained analytically and confirmed by direct numerical many-spin simulations. As a result, the method can be applied to a wide range of solid-state systems.« less

  4. Highly selective detection of individual nuclear spins with rotary echo on an electron spin probe

    SciTech Connect

    Mkhitaryan, V. V.; Jelezko, F.; Dobrovitski, V. V.

    2015-10-26

    We consider an electronic spin, such as a nitrogen-vacancy center in diamond, weakly coupled to a large number of nuclear spins, and subjected to the Rabi driving with a periodically alternating phase. We show that by switching the driving phase synchronously with the precession of a given nuclear spin, the interaction to this spin is selectively enhanced, while the rest of the bath remains decoupled. The enhancement is of resonant character. The key feature of the suggested scheme is that the width of the resonance is adjustable, and can be greatly decreased by increasing the driving strength. Thus, the resonance can be significantly narrowed, by a factor of 10–100 in comparison with the existing detection methods. Significant improvement in selectivity is explained analytically and confirmed by direct numerical many-spin simulations. As a result, the method can be applied to a wide range of solid-state systems.

  5. Highly selective detection of individual nuclear spins with rotary echo on an electron spin probe

    NASA Astrophysics Data System (ADS)

    Mkhitaryan, V. V.; Jelezko, F.; Dobrovitski, V. V.

    2015-10-01

    We consider an electronic spin, such as a nitrogen-vacancy center in diamond, weakly coupled to a large number of nuclear spins, and subjected to the Rabi driving with a periodically alternating phase. We show that by switching the driving phase synchronously with the precession of a given nuclear spin, the interaction to this spin is selectively enhanced, while the rest of the bath remains decoupled. The enhancement is of resonant character. The key feature of the suggested scheme is that the width of the resonance is adjustable, and can be greatly decreased by increasing the driving strength. Thus, the resonance can be significantly narrowed, by a factor of 10100 in comparison with the existing detection methods. Significant improvement in selectivity is explained analytically and confirmed by direct numerical many-spin simulations. The method can be applied to a wide range of solid-state systems.

  6. Highly selective detection of individual nuclear spins with rotary echo on an electron spin probe

    PubMed Central

    Mkhitaryan, V. V.; Jelezko, F.; Dobrovitski, V. V.

    2015-01-01

    We consider an electronic spin, such as a nitrogen-vacancy center in diamond, weakly coupled to a large number of nuclear spins, and subjected to the Rabi driving with a periodically alternating phase. We show that by switching the driving phase synchronously with the precession of a given nuclear spin, the interaction to this spin is selectively enhanced, while the rest of the bath remains decoupled. The enhancement is of resonant character. The key feature of the suggested scheme is that the width of the resonance is adjustable, and can be greatly decreased by increasing the driving strength. Thus, the resonance can be significantly narrowed, by a factor of 10100 in comparison with the existing detection methods. Significant improvement in selectivity is explained analytically and confirmed by direct numerical many-spin simulations. The method can be applied to a wide range of solid-state systems. PMID:26497777

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

    SciTech Connect

    Götz, Andreas W.; Autschbach, Jochen; Visscher, Lucas

    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.

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

    NASA Astrophysics Data System (ADS)

    Götz, Andreas W.; Autschbach, Jochen; Visscher, Lucas

    2014-03-01

    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 199Hg and 13C upon coordination of dimethylsulfoxide solvent molecules.

  9. Vanishing current hysteresis under competing nuclear spin pumping processes in a quadruplet spin-blockaded double quantum dot

    SciTech Connect

    Amaha, S.; Hatano, T.; Tarucha, S.; Gupta, J. A.; Austing, D. G.

    2015-04-27

    We investigate nuclear spin pumping with five-electron quadruplet spin states in a spin-blockaded weakly coupled vertical double quantum dot device. Two types of hysteretic steps in the leakage current are observed on sweeping the magnetic field and are associated with bidirectional polarization of nuclear spin. Properties of the steps are understood in terms of bias-voltage-dependent conditions for the mixing of quadruplet and doublet spin states by the hyperfine interaction. The hysteretic steps vanish when up- and down-nuclear spin pumping processes are in close competition.

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

    NASA Astrophysics Data System (ADS)

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

    2015-11-01

    Dynamical nuclear polarization holds the key for orders of magnitude enhancements of nuclear magnetic resonance signals which, in turn, would enable a wide range of novel applications in biomedical sciences. However, current implementations of DNP require cryogenic temperatures and long times for achieving high polarization. Here we propose and analyze 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.

  11. Spin constraints on nuclear energy density functionals

    NASA Astrophysics Data System (ADS)

    Robledo, L. M.; Bernard, R. N.; Bertsch, G. F.

    2014-02-01

    The Gallagher-Moszkowski rule in the spectroscopy of odd-odd nuclei imposes a new spin constraint on the energy functionals for self-consistent mean field theory. The commonly used parametrization of the effective three-body interaction in the Gogny and Skyrme families of energy functionals is ill suited to satisfy the spin constraint. In particular, the Gogny parametrization of the three-body interaction has the spin dependence opposite to that required by the observed spectra. The two-body part has a correct sign, but in combination the rule is violated as often as not. We conclude that a new functional form is needed for the effective three-body interaction that can take into better account the different spin-isospin channels of the interaction.

  12. Dephasing due to Nuclear Spins in Large-Amplitude Electric Dipole Spin Resonance.

    PubMed

    Chesi, Stefano; Yang, Li-Ping; Loss, Daniel

    2016-02-12

    We analyze effects of the hyperfine interaction on electric dipole spin resonance when the amplitude of the quantum-dot motion becomes comparable or larger than the quantum dot's size. Away from the well-known small-drive regime, the important role played by transverse nuclear fluctuations leads to a Gaussian decay with characteristic dependence on drive strength and detuning. A characterization of spin-flip gate fidelity, in the presence of such additional drive-dependent dephasing, shows that vanishingly small errors can still be achieved at sufficiently large amplitudes. Based on our theory, we analyze recent electric dipole spin resonance experiments relying on spin-orbit interactions or the slanting field of a micromagnet. We find that such experiments are already in a regime with significant effects of transverse nuclear fluctuations and the form of decay of the Rabi oscillations can be reproduced well by our theory. PMID:26919009

  13. Dephasing due to Nuclear Spins in Large-Amplitude Electric Dipole Spin Resonance

    NASA Astrophysics Data System (ADS)

    Chesi, Stefano; Yang, Li-Ping; Loss, Daniel

    2016-02-01

    We analyze effects of the hyperfine interaction on electric dipole spin resonance when the amplitude of the quantum-dot motion becomes comparable or larger than the quantum dot's size. Away from the well-known small-drive regime, the important role played by transverse nuclear fluctuations leads to a Gaussian decay with characteristic dependence on drive strength and detuning. A characterization of spin-flip gate fidelity, in the presence of such additional drive-dependent dephasing, shows that vanishingly small errors can still be achieved at sufficiently large amplitudes. Based on our theory, we analyze recent electric dipole spin resonance experiments relying on spin-orbit interactions or the slanting field of a micromagnet. We find that such experiments are already in a regime with significant effects of transverse nuclear fluctuations and the form of decay of the Rabi oscillations can be reproduced well by our theory.

  14. 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.; Atatre, 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.

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

    SciTech Connect

    Zobov, V. E.

    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 β{sub I} in addition to the electron polarization β{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 β{sub S} ≈ β{sub I} and small times. At large times, such correlations decay and multispin correlations ensuring nonzero mutual information and zero quantum discord become dominant.

  16. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization

    NASA Astrophysics Data System (ADS)

    Mentink-Vigier, Frederic; Akbey, Ümit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva

    2015-09-01

    Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160 K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea -eb - n } during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This study also shows the complexity of the MAS-DNP process and therefore the necessity to rely on numerical simulations for understanding parametric dependencies of the enhancements. Finally an extension of the spin system up to five spins allowed us to probe the first steps of the transfer of polarization from the nuclei coupled to the electrons to further away nuclei, demonstrating a decrease in the spin-diffusion barrier under MAS conditions.

  17. Theoretical aspects of Magic Angle Spinning - Dynamic Nuclear Polarization.

    PubMed

    Mentink-Vigier, Frederic; Akbey, mit; Oschkinat, Hartmut; Vega, Shimon; Feintuch, Akiva

    2015-09-01

    Magic Angle Spinning (MAS) combined with Dynamic Nuclear Polarization (DNP) has been proven in recent years to be a very powerful method for increasing solid-state NMR signals. Since the advent of biradicals such as TOTAPOL to increase the nuclear polarization new classes of radicals, with larger molecular weight and/or different spin properties have been developed. These have led to unprecedented signal gain, with varying results for different experimental parameters, in particular the microwave irradiation strength, the static field, and the spinning frequency. Recently it has been demonstrated that sample spinning imposes DNP enhancement processes that differ from the active DNP mechanism in static samples as upon sample spinning the DNP enhancements are the results of energy level anticrossings occurring periodically during each rotor cycle. In this work we present experimental results with regards to the MAS frequency dependence of the DNP enhancement profiles of four nitroxide-based radicals at two different sets of temperature, 110 and 160K. In fact, different magnitudes of reduction in enhancement are observed with increasing spinning frequency. Our simulation code for calculating MAS-DNP powder enhancements of small model spin systems has been improved to extend our studies of the influence of the interaction and relaxation parameters on powder enhancements. To achieve a better understanding we simulated the spin dynamics of a single three-spin system {ea-eb-n} during its steady state rotor periods and used the Landau-Zener formula to characterize the influence of the different anti-crossings on the polarizations of the system and their necessary action for reaching steady state conditions together with spin relaxation processes. Based on these model calculations we demonstrate that the maximum steady state nuclear polarization cannot become larger than the maximum polarization difference between the two electrons during the steady state rotor cycle. This study also shows the complexity of the MAS-DNP process and therefore the necessity to rely on numerical simulations for understanding parametric dependencies of the enhancements. Finally an extension of the spin system up to five spins allowed us to probe the first steps of the transfer of polarization from the nuclei coupled to the electrons to further away nuclei, demonstrating a decrease in the spin-diffusion barrier under MAS conditions. PMID:26232770

  18. Optical Polarization of Nuclear Spins in Silicon Carbide.

    PubMed

    Falk, Abram L; Klimov, Paul V; Ivdy, Viktor; Szsz, Krisztin; Christle, David J; Koehl, William F; Gali, dm; Awschalom, David D

    2015-06-19

    We demonstrate optically pumped dynamic nuclear polarization of (29)Si nuclear spins that are strongly coupled to paramagnetic color centers in 4H- and 6H-SiC. The 99%1% degree of polarization that we observe at room temperature corresponds to an effective nuclear temperature of 5???K. By combining ab initio theory with the experimental identification of the color centers' optically excited states, we quantitatively model how the polarization derives from hyperfine-mediated level anticrossings. These results lay a foundation for SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for magnetic resonance imaging. PMID:26197014

  19. Optical Polarization of Nuclear Spins in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Falk, Abram L.; Klimov, Paul V.; Ivdy, Viktor; Szsz, Krisztin; Christle, David J.; Koehl, William F.; Gali, dm; Awschalom, David D.

    2015-06-01

    We demonstrate optically pumped dynamic nuclear polarization of 29Si nuclear spins that are strongly coupled to paramagnetic color centers in 4 H - and 6 H -SiC. The 9 9 % 1 % degree of polarization that we observe at room temperature corresponds to an effective nuclear temperature of 5 ? K . By combining ab initio theory with the experimental identification of the color centers' optically excited states, we quantitatively model how the polarization derives from hyperfine-mediated level anticrossings. These results lay a foundation for SiC-based quantum memories, nuclear gyroscopes, and hyperpolarized probes for magnetic resonance imaging.

  20. Hole - Nuclear Spin Interaction in Semiconductor Quantum Dots

    NASA Astrophysics Data System (ADS)

    Marie, Xavier

    2010-03-01

    Spins of localized electrons in semiconductor quantum dots (QDs) are attractive for future spintronic and quantum information devices since they are not subject to the classical spin relaxation mechanisms known for free carriers [1]. It is now well established that the main spin dephasing mechanism in QDs is due to the coupling of conduction electron spin with the randomly fluctuating nuclear spins (Fermi contact term) [2-5]. For a valence electron (or hole), this coupling is expected to be much weaker because of the p-symmetry of the valence band states and no experimental evidence of such a hole-nuclear spin interaction has been reported so far [6]. We have measured the carrier spin dynamics in p-doped InAs/GaAs quantum dots by pump probe and time-resolved photoluminescence experiments. We demonstrate that the hole spin dynamics in these QDs is governed by the interaction with randomly fluctuating nuclear spins [7]. Our calculations based on dipole-dipole coupling between the hole and the quantum dot nuclei lead to a hole spin dephasing time for an ensemble of dots of 15 ns in close agreement with experiments.[4pt] In collaboration with B. Eble, C. Testelin, F. Bernardot, and M. Chamarro, Institut des Nanosciences de Paris, Universit'e P. et M. Curie, CNRS, Paris, F-75015 France; A. Balocchi, T. Amand, and B. Urbaszek, Universit'e de Toulouse ; LPCNO, INSA-CNRS-UPS, 135 av. de Rangueil, 31077 Toulouse Cedex 4, France; and A. Lematre, Laboratoire de Photonique et de Nanostructures, CNRS, Route de Nozay, F-91460, Marcoussis, France. [4pt] [1] Spin Physics in Semiconductors, edited by M. D'Yakonov (Springer, Berlin, 2008) [0pt] [2] I. Merkulov et al, Phys. Rev. B 65, 205309 (2002) [0pt] [3] P.-F. Braun, X. Marie et al, PRL 94, 116601 (2005) [0pt] [4] A. C. Johnson et al , Nature 435, 925 (2005) [0pt] [5] A. Greilich et al, Science 313, 341(2006) [0pt] [6] S. Laurent et al, Phys. Rev. Lett. 94, 147401 (2005) [0pt] [7] B. Eble et al, Phys. Rev. Lett. 102, 146601 (2009)

  1. Nuclear Spin Gyroscope Based on an Atomic Comagnetometer

    SciTech Connect

    Kornack, T.W.; Ghosh, R.K.; Romalis, M.V.

    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.

  2. From conventional (neutron-proton) nuclear scissors to spin nuclear scissors

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    Investigations of the nuclear scissors mode in the frame of the Wigner Function Moments (WFM) method leading to the discovery of the new types of the nuclear collective motion are reviewed. It is demonstrated how the generalization of WFM method to take into account spin degrees of freedom allows one to reproduce all earlier described qualitative features of the conventional (neutron-proton) nuclear scissors (deformation dependence of the energy and transition probabilities, connection with isovector GQR implying the Fermi surface deformation, flows) and allows one to reveal a variety of new collective modes: isovector and isoscalar spin scissors, the relative motion of the orbital angular momentum and spin, isovector and isoscalar spin-vector GQR, spin-flip excitations.

  3. 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. )

    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%).

  4. Observation of scalar nuclear spinspin coupling in van der Waals complexes

    PubMed Central

    Ledbetter, Micah P.; Saielli, Giacomo; Bagno, Alessandro; Tran, Nhan; Romalis, Michael V.

    2012-01-01

    Scalar couplings between covalently bound nuclear spins are a ubiquitous feature in nuclear magnetic resonance (NMR) experiments, imparting valuable information to NMR spectra regarding molecular structure and conformation. Such couplings arise due to a second-order hyperfine interaction, and, in principle, the same mechanism should lead to scalar couplings between nuclear spins in unbound van der Waals complexes. Here, we report the first observation of scalar couplings between nuclei in van der Waals complexes. Our measurements are performed in a solution of hyperpolarized 129Xe and pentane, using superconducting quantum interference devices to detect NMR in 10mG fields, and are in good agreement with calculations based on density functional theory. van der Waals forces play an important role in many physical phenomena. The techniques presented here may provide a new method for probing such interactions.

  5. Decoherence-protected nuclear spin quantum register in diamond

    NASA Astrophysics Data System (ADS)

    Dobrovitski, Viatcheslav; Kuo, Wan Jung; Hanson, Ronald; Taminiau, Tim H.

    2013-03-01

    We analyze the decoherence-protected operation of a quantum register based on the nuclear spins surrounding a nitrogen-vacancy (NV) center in diamond. Combination of the decoherence protection with the quantum gates is achieved by applying the decoupling pulses to the NV center's electronic spin in resonance with the motion of one of the nuclear spins. In this way, many weakly coupled (tens of kHz) nuclei located far from the NV center can be combined in a quantum register. We study the limits, set by realistic experimental parameters, on the size of such a register and on the duration of the quantum gates needed for its operation. We also consider the ways of accelerating the quantum gate operation, and integration of the decoherence-protected gates with the decoupling of the nuclear spins themselves. We conclude that creation of such registers is feasible with current experimental capabilities. Work at the Ames Laboratory was supported by the Department of Energy - Basic Energy Sciences under Contract No. DE-AC02-07CH11358.

  6. 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.

    2015-03-01

    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 14N nuclear spin qubit intrinsic to a nitrogen-vacancy center in high purity diamond. This phase gate is achieved by utilizing electron-nuclear hyperfine interaction. By driving off-resonant Rabi oscillations on the electronic spin, we can generate an arbitrary phase gate on the nuclear spin. We also demonstrate that repeated applications of ?-phase gates can bang-bang decouple the nuclear spin from the environment, locking the spin state for up to 140 ?s. Research was supported by the Sloan and Packard Foundations, the National Science Foundation through Awards DMR-0819860 and DMR-0846341, and the Army Research Office through PECASE Award W911NF-08-1-0189.

  7. Spin dynamics of density wave and frustrated spin systems probed by nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Lumata, Lloyd L.

    This dissertation encompasses my major experimental work using nuclear magnetic resonance (NMR) to probe the local magnetism and spin dynamics of two interesting systems in condensed matter: density wave and frustrated spin systems. Density waves are ordered ground states formed due to the instability in low-dimensions while frustrated spin systems inhibit long-range magnetic ordering due to their corner-shared triangular structure. The first part of this dissertation entails a discussion of the broken symmetry ground states in low dimensional systems: spin density waves (SDW), charge density waves (CDW), and spin-Peierls (SP) states. Simultaneous 77Se NMR and electrical transport is employed to investigate the spin density wave (SDW) ground state in the quasi-one-dimensional (Q1D) organic conductor (TMTSF)2PF6 and the field-induced spin density wave (FISDW) transitions in (TMTSF)2ClO4. Furthermore, angular-dependent measurements were taken at very high magnetic fields to probe the anisotropic properties of FISDW subphases, giving insight into the electronic structure in the quantum limit. The CDW and SP ground states in another Q1D organic conductor (Per)2Pt[mnt]2 were studied using 195Pt NMR revealing the breaking of the SP state at high magnetic fields. The role of doping in the electronic correlations of the newly discovered CDW-superconductor CuxTiSe 2 is revealed by 63Cu and 77Se NMR. The later part of this dissertation focuses on the kagome spin systems which show very interesting phenomena due to magnetic frustration. Using 69,71Ga NMR, the dynamical behavior of spins in the spin-liquid state in one of the first rare-earth kagome materials Pr3Ga 5SiO14 is described and compared with other existing frustrated spin systems. On the other hand, 93Nb NMR on structurally similar material Ba3NbFe3Si2O14 provides an opportunity to study multiferroicity in a geometrically frustrated lattice. This work shows how NMR contributes to the understanding of these two distinct classes of condensed matter systems.

  8. 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.

  9. Nuclear-spin-lattice relaxation in rhenium metal

    SciTech Connect

    Dimitropoulos, C.; Bucher, J.P.; Borsa, F.; Corti, M.

    1989-04-01

    Nuclear-spin-lattice relaxation measurements are presented for /sup 187/Re in Re metal as a function of temperature. The relaxation transition probabilities were extracted from the nuclear magnetization recovery curves both in high magnetic field (H/sub 0/ = 8 T) nuclear-magnetic-resonance experiments and in nuclear-quadrupole-resonance (H/sub 0/ = 0) experiments. It is found that the dominant relaxation mechanisms is due to magnetic rather then quadrupolar hyperfine interaction with W/sub M/ = 1.32 T. The data are analyzed in terms of the electronic structure of Re metal. The analysis confirms that Re is a ''weakly enhanced'' transition metal with a nuclear relaxation rate dominated by the s-contact hyperfine interaction.

  10. Storing entanglement of nuclear spins via Uhrig dynamical decoupling

    SciTech Connect

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

    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.

  11. Flux-vector model of spin noise in superconducting circuits: Electron versus nuclear spins and role of phase transition

    NASA Astrophysics Data System (ADS)

    LaForest, S.; de Sousa, Rogério

    2015-08-01

    Superconducting quantum interference devices (SQUIDs) and other superconducting circuits are limited by intrinsic flux noise with spectral density 1 /fα with α <1 whose origin is believed to be due to spin impurities. Here, we present a theory of flux noise that takes into account the vectorial nature of the coupling of spins to superconducting wires. We present explicit numerical calculations of the flux-noise power (spectral density integrated over all frequencies) for electron impurities and lattice nuclear spins under several different assumptions. The noise power is shown to be dominated by surface electron spins near the wire edges, with bulk lattice nuclear spins contributing ˜5 % of the noise power in aluminum and niobium wires. We consider the role of electron spin phase transitions, showing that the spin-spin correlation length (describing, e.g., the average size of ferromagnetic spin clusters) greatly impacts the scaling of flux noise with wire geometry. Remarkably, the flux-noise power is exactly equal to zero when the spins are polarized along the flux-vector direction, forming what we call a poloidal state. Flux noise is nonzero for other spin textures, but gets reduced in the presence of correlated ferromagnetic fluctuations between the top and bottom wire surfaces, where the flux vectors are antiparallel. This demonstrates that engineering spin textures and/or intersurface correlation provides a method to reduce flux noise in superconducting devices.

  12. Spin Density Matrices for Nuclear Density Functionals with Parity Violation

    NASA Astrophysics Data System (ADS)

    Barrett, Bruce; Giraud, Bertrand

    2010-11-01

    Within the context of the radial density functional [1], we apply the spin density matrix (SDM) used in atomic and molecular physics [2] to nuclear physics. The vector part of the SDM defines a ``hedgehog'' situation, which exists only if nuclear states contain some amount of parity violation. Thus, looking for the vector profile of the SDM could be used as a test for parity violation in nuclei. The difference between the scalar profile and the vector profile of the SDM will be illustrated by a toy model. [4pt] [1] B. G. Giraud, Phys. Rev. C 78, 014307 (2008).[0pt] [2] A. Goerling, Phys. Rev. A 47, 2783 (1993).

  13. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond

    NASA Astrophysics Data System (ADS)

    King, Jonathan P.; Jeong, Keunhong; Vassiliou, Christophoros C.; Shin, Chang S.; Page, Ralph H.; Avalos, Claudia E.; Wang, Hai-Jing; Pines, Alexander

    2015-12-01

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ~170,000 over thermal equilibrium. The signal of the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. Hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions.

  14. Monitoring nuclear spin-flip processes and measuring spin-diffusion constants via hole burning into the magnetization

    NASA Astrophysics Data System (ADS)

    Roos, M.; Micke, P.; Hempel, G.

    2012-05-01

    An NMR experiment is presented for measuring spin-diffusion coefficients and observing homonuclear spin-flip processes. The magnetization is erased or even inverted in a multitude of spatially confined regions containing only one or a few spins (hole burning'). During the following time evolution of these holes, the following three time regimes can be observed: (i) local spin dynamics, (ii) spin diffusion towards a uniform average magnetization, and (iii) longitudinal nuclear magnetic relaxation. The oscillating characteristic of magnetization exchange between neighboring protons is demonstrated on a liquid crystal.

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

    NASA Astrophysics Data System (ADS)

    Munsch, Mathieu; Wst, 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.

  16. Nuclear spin-spin coupling in a van der Waals-bonded system: xenon dimer.

    PubMed

    Vaara, Juha; Hanni, Matti; Jokisaari, Jukka

    2013-03-14

    Nuclear spin-spin coupling over van der Waals bond has recently been observed via the frequency shift of solute protons in a solution containing optically hyperpolarized (129)Xe nuclei. We carry out a first-principles computational study of the prototypic van der Waals-bonded xenon dimer, where the spin-spin coupling between two magnetically non-equivalent isotopes, J((129)Xe - (131)Xe), is observable. We use relativistic theory at the four-component Dirac-Hartree-Fock and Dirac-density-functional theory levels using novel completeness-optimized Gaussian basis sets and choosing the functional based on a comparison with correlated ab initio methods at the nonrelativistic level. J-coupling curves are provided at different levels of theory as functions of the internuclear distance in the xenon dimer, demonstrating cross-coupling effects between relativity and electron correlation for this property. Calculations on small Xe clusters are used to estimate the importance of many-atom effects on J((129)Xe - (131)Xe). Possibilities of observing J((129)Xe - (131)Xe) in liquid xenon are critically examined, based on molecular dynamics simulation. A simplistic spherical model is set up for the xenon dimer confined in a cavity, such as in microporous materials. It is shown that the on the average shorter internuclear distance enforced by the confinement increases the magnitude of the coupling as compared to the bulk liquid case, rendering J((129)Xe - (131)Xe) in a cavity a feasible target for experimental investigation. PMID:23514495

  17. Nuclear spin conversion in NH{sub 3}

    SciTech Connect

    Cacciani, P.; Cosleou, J.; Khelkhal, M.; Tudorie, M.; Puzzarini, C.; Pracna, P.

    2009-10-15

    The nuclear spin conversion (NSC) rate for a gas sample of NH{sub 3} is calculated in the framework of the quantum relaxation model. It is based on the knowledge of the vibration-inversion levels of the lowest vibrational states, the relaxation rates, and the intramolecular magnetic interactions. The magnitudes of the spin-spin and spin-rotation interaction terms have been obtained with the help of ab initio calculations. The value of the NSC at 296 K for a pressure of 1 Torr is 3.23x10{sup -6} s{sup -1} for {sup 14}NH{sub 3} and 9.15x10{sup -6} s{sup -1} for {sup 15}NH{sub 3}. A linear dependence of the NSC rates on the pressure is valid up to 1 atm for {sup 14}NH{sub 3} and up to 30 Torr for {sup 15}NH{sub 3}, where quasidegenerate ortho/para pairs are present in the excited {nu}{sub 2}=1 state.

  18. Imaging nuclear spins weakly coupled to a probe paramagnetic center

    NASA Astrophysics Data System (ADS)

    Laraoui, Abdelghani; Pagliero, Daniela; Meriles, Carlos A.

    2015-05-01

    Optically detected paramagnetic centers in wide-band-gap semiconductors are emerging as a promising platform for nanoscale metrology at room temperature. Of particular interest are applications where the center is used as a probe to interrogate other spins that cannot be observed directly. Using the nitrogen-vacancy (NV) center in diamond as a model system, we propose a strategy to determine the spatial coordinates of weakly coupled nuclear spins. The central idea is to label the target nucleus with a spin polarization that depends on its spatial location, which is subsequently revealed by making this polarization flow back to the NV for readout. Using extensive analytical and numerical modeling, we show that the technique can attain high spatial resolution depending on the NV lifetime and target spin location. No external magnetic field gradient is required, which circumvents complications resulting from changes in the direction of the applied magnetic field, and considerably simplifies the required instrumentation. Extensions of the present technique may be adapted to pinpoint the locations of other paramagnetic centers in the NV vicinity or to yield information on dynamical processes in molecules on the diamond surface.

  19. 129Xe EDM Search Experiment Using Active Nuclear Spin Maser

    NASA Astrophysics Data System (ADS)

    Sato, Tomoya; Ichikawa, Yuichi; Ohtomo, Yuichi; Sakamoto, Yu; Kojima, Shuichiro; Suzuki, Takahiro; Shirai, Hazuki; Chikamori, Masatoshi; Hikota, Eri; Miyatake, Hirokazu; Nanao, Tsubasa; Suzuki, Kunifumi; Tsuchiya, Masato; Inoue, Takeshi; Furukawa, Takeshi; Yoshimi, Akihiro; Bidinosti, Christopher P.; Ino, Takashi; Ueno, Hideki; Matsuo, Yukari; Fukuyama, Takeshi; Asahi, Koichiro

    An active nuclear spin maser, which enables a precision measurement of spin precession frequency, is employed in the experimental search for permanent electric dipole moment (EDM) in the diamagnetic atom 129Xe. In order to eliminate systematic errors which limit the sensitivity of the experiment to an EDM, the following tactics are adopted: (i) 3He comagnetometry for the cancellation of long-term drifts in the external magnetic fields and (ii) double-cell geometry for the mitigation of frequency shifts due to interaction of 129Xe spin with polarized Rb atoms. In the present work, the design for the double-cell has been changed and a magnetic shield-coil system to provide a highly homogeneous magnetic field has been newly introduced. Thanks to increased polarization and longer 3He spin relaxation time, the dual-species maser of 129Xe and 3He in a double-cell geometry operated successfully. Our experiment is now at the stage of assembling these separate technical elements in order to start the measurement of 129Xe EDM in the 10-28 ecm region.

  20. Solid effect in magic angle spinning dynamic nuclear polarization

    PubMed Central

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

    2012-01-01

    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 \\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{upgreek} \\usepackage{mathrsfs} \\setlength{\\oddsidemargin}{-69pt} \\begin{document} \\begin{equation*}\\omega _0 ^{ - 2}\\end{equation*} \\end{document}?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. PMID:22894339

  1. 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 ω _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 ɛ = 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.

  2. 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.

  3. Quantum Information Processing Experiments Using Nuclear and Electron Spins in Molecules

    NASA Astrophysics Data System (ADS)

    Kitagawa, Masahiro; Morita, Yasushi; Kagawa, Akinori; Negoro, Makoto

    Nuclear spins and electron spins in molecules have relatively long decoherence times, offer appropriate interactions for use in quantum gate operations, and can be controlled using magnetic resonance techniques. In this chapter, from the viewpoint of using these spins for quantum information processing, Hamiltonian engineering methods and hardware are developed for hyper precision control. Additionally, hyperpolarization techniques are developed for spin initialization, and a spin amplification method is developed for detection.

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

    NASA Astrophysics Data System (ADS)

    Bragar, Igor; Cywiński, Łukasz

    2015-04-01

    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 the 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 the appearance of entanglement sudden death at finite time for two qubits initialized in a Bell state. For these fields, the intrabath dipolar interactions and spatial inhomogeneity of hyperfine couplings are irrelevant on the time scale 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 π pulses to the two spins. All the currently relevant for experiments bath states are considered: the thermal state, narrowed states (characterized by diminished uncertainty of one of the components of the Overhauser field) of two uncorrelated baths, and a correlated narrowed state with a 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 show that their entanglement dynamics can be reconstructed from measurements of the currently relevant for experiments entanglement witnesses and the fidelity of quantum teleportation, performed using a partially disentangled state as a resource.

  5. 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.

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

    PubMed

    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

  7. 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.

  8. Spin and spin-isospin instabilities in asymmetric nuclear matter at zero and finite temperatures using Skyrme functionals

    SciTech Connect

    Chamel, N.; Goriely, S.

    2010-10-15

    Self-consistent mean-field methods based on phenomenological Skyrme effective interactions are known to exhibit spurious spin and spin-isospin instabilities both at zero and finite temperatures when applied to homogeneous nuclear matter at the densities encountered in neutron stars and in supernova cores. The origin of these instabilities is revisited in the framework of the nuclear energy density functional theory, and a simple prescription is proposed to remove them. The stability of several Skyrme parametrizations is reexamined.

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

    SciTech Connect

    Mamone, Salvatore Concistrè, Maria; Carignani, Elisa; Meier, Benno; Krachmalnicoff, Andrea; Johannessen, Ole G.; Denning, Mark; Carravetta, Marina; Whitby, Richard J.; Levitt, Malcolm H.; Lei, Xuegong; Li, Yongjun; Goh, Kelvin; Horsewill, Anthony J.

    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.

  10. Quenching of dynamic nuclear polarization by spinorbit coupling in GaAs quantum dots

    PubMed Central

    Nichol, John M.; Harvey, Shannon P.; Shulman, Michael D.; Pal, Arijeet; Umansky, Vladimir; Rashba, Emmanuel I.; Halperin, Bertrand I.; Yacoby, Amir

    2015-01-01

    The central-spin problem is a widely studied model of quantum decoherence. Dynamic nuclear polarization occurs in central-spin systems when electronic angular momentum is transferred to nuclear spins and is exploited in quantum information processing for coherent spin manipulation. However, the mechanisms limiting this process remain only partially understood. Here we show that spinorbit coupling can quench dynamic nuclear polarization in a GaAs quantum dot, because spin conservation is violated in the electronnuclear system, despite weak spinorbit coupling in GaAs. Using LandauZener sweeps to measure static and dynamic properties of the electron spinflip probability, we observe that the size of the spinorbit and hyperfine interactions depends on the magnitude and direction of applied magnetic field. We find that dynamic nuclear polarization is quenched when the spinorbit contribution exceeds the hyperfine, in agreement with a theoretical model. Our results shed light on the surprisingly strong effect of spinorbit coupling in central-spin systems. PMID:26184854

  11. 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

  12. 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.

  13. Nuclear Spin Locking and Extended Two-Electron Spin Decoherence Time in an InAs Quantum Dot Molecule

    NASA Astrophysics Data System (ADS)

    Chow, Colin; Ross, Aaron; Steel, Duncan; Sham, L. J.; Bracker, Allan; Gammon, Daniel

    2015-03-01

    The spin eigenstates for two electrons confined in a self-assembled InAs quantum dot molecule (QDM) consist of the spin singlet state, S, with J = 0 and the triplet states T-, T0 and T+, with J = 1. When a transverse magnetic field (Voigt geometry) is applied, the two-electron system can be initialized to the different states with appropriate laser excitation. Under the excitation of a weak probe laser, non-Lorentzian lineshapes are obtained when the system is initialized to either T- or T+, where T- results in a ``resonance locking'' lineshape while T+ gives a ``resonance avoiding '' lineshape: two different manifestations of hysteresis showing the importance of memory in the system. These observations signify dynamic nuclear spin polarization (DNSP) arising from a feedback mechanism involving hyperfine interaction between lattice nuclei and delocalized electron spins, and Overhauser shift due to nuclear spin polarization. Using pump configurations that generate coherent population trapping, the isolation of the electron spin from the optical excitation shows the stabilization of the nuclear spin ensemble. The dark-state lineshape measures the lengthened electron spin decoherence time, from 1 ns to 1 ?s. Our detailed spectra highlight the potential of QDM for realizing a two-qubit gate. This work is supported by NSF, ARO, AFOSR, DARPA, and ONR.

  14. Nuclear spin-dependent parity nonconservation in diatomic molecules

    NASA Astrophysics Data System (ADS)

    Murphree, Dennis Haaga, Jr.

    Nuclear spin-dependent parity nonconserving phenomena produce effects that are relevant to particle, nuclear, and atomic physics. They unite these increasingly disparate disciplines via the subtle effects of the weak force. Currently, weak interactions between nucleons present at best a confusing picture, and neutral weak coupling of leptons to baryons, even at high energy, is one of the most poorly characterized aspects of the Standard Model. Perhaps surprisingly, one of the most effective laboratories for studying parity violation is the diatomic molecule. The naturally close spacing of molecular hyperfine-rotational levels, which can be Zeeman shifted even closer to degeneracy, allows small parity violating effects to be enhanced dramatically. Here we describe the beginning of our experimental program to study nuclear spin-dependent parity nonconservation (NSD-PNC) using a beam of diatomic free radicals. Specifically, we seek to measure weak matrix elements connecting hyperfine-rotational states in a series of molecules, beginning with barium fluoride. Our experimental technique is based on a Stark interference method: we look for asymmetries in transitions that depend on the sign of an applied electric field. A key element in the experimental program is the magnetic field used to Zeeman shift the levels in our molecules to near crossing. Carefully controlling both the strength and uniformity of this field is critical to the success of the experiment. In order to measure the field over the wide range of values required by our experiment, both a completely novel nuclear magnetic resonance probe, as well as a unique field shimming apparatus and algorithm, were developed. A second important element in the program is the ability to detect the states of our molecules with as high a signal to noise as possible. To that end a new detection method based on a two-photon transition was developed. Both of these areas, which constitute the bulk of the author's contribution to the experimental program, are described in detail.

  15. Radioactive nuclear beams and the North American IsoSpin Laboratory (ISL) initiative

    SciTech Connect

    Casten, R.F.

    1992-01-01

    Radioactive nuclear beams (RNBs) offer exciting new research opportunities in fields as diverse as nuclear structure, nuclear reactions, astrophysics atomic, materials, and applied science. Their realization in new accelerator complexes also offers important technical challenges. Some of the nuclear physics possibilities afforded by RNBs, with emphasis on low spin nuclear structure, are discussed, accompanied by an outline of the ISL initiative and its status.

  16. Radioactive nuclear beams and the North American IsoSpin Laboratory (ISL) initiative

    SciTech Connect

    Casten, R.F.

    1992-12-01

    Radioactive nuclear beams (RNBs) offer exciting new research opportunities in fields as diverse as nuclear structure, nuclear reactions, astrophysics atomic, materials, and applied science. Their realization in new accelerator complexes also offers important technical challenges. Some of the nuclear physics possibilities afforded by RNBs, with emphasis on low spin nuclear structure, are discussed, accompanied by an outline of the ISL initiative and its status.

  17. Nanometre-scale nuclear-spin device for quantum information processing

    NASA Astrophysics Data System (ADS)

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

    2006-05-01

    We have developed semiconductor point contact devices in which nuclear spins in a nanoscale region are coherently controlled by all-electrical methods. Different from the standard nuclear-magnetic resonance technique, the longitudinal magnetization of nuclear spins is directly detected by measuring resistance, resulting in ultra-sensitive detection of the microscopic quantity of nuclear spins. All possible coherent oscillations have been successfully demonstrated between two levels from four nuclear spin states of I = 3/2 nuclei. Quantum information processing is discussed based on two fictitious qubits of an I = 3/2 system and methods are described for performing arbitrary logical gates both on one and two qubits. A scheme for quantum state tomography based on Mz-detection is also proposed. As the starting point of quantum manipulations, we have experimentally prepared the effective pure states for the I = 3/2 nuclear spin system.

  18. Manipulation and measurement of nuclear spin over the quantum Hall regime for quantum information processing

    NASA Astrophysics Data System (ADS)

    Mani, R. G.; Johnson, W. B.; Narayanamurti, V.

    2002-12-01

    We propose a method for the management of nuclear spin immersed in a confined quantum Hall electronic system that is characterized by: (a) the application of the Overhauser effect for dynamic nuclear polarization, (b) spin measurement using electrical resistance detection techniques, (c) spin control with microwave/radio frequency methods, and (d) the utilization of the electronic spin exciton as a possible mobile spin transfer mechanism for the eventual realization of a logic gate. Concepts involved in this approach are illustrated with experimental results.

  19. Nuclear depolarization and absolute sensitivity in magic-angle spinning cross effect dynamic nuclear polarization.

    PubMed

    Mentink-Vigier, Frédéric; Paul, Subhradip; Lee, Daniel; Feintuch, Akiva; Hediger, Sabine; Vega, Shimon; De Paëpe, Gaël

    2015-09-14

    Over the last two decades solid state Nuclear Magnetic Resonance has witnessed a breakthrough in increasing the nuclear polarization, and thus experimental sensitivity, with the advent of Magic Angle Spinning Dynamic Nuclear Polarization (MAS-DNP). To enhance the nuclear polarization of protons, exogenous nitroxide biradicals such as TOTAPOL or AMUPOL are routinely used. Their efficiency is usually assessed as the ratio between the NMR signal intensity in the presence and the absence of microwave irradiation εon/off. While TOTAPOL delivers an enhancement εon/off of about 60 on a model sample, the more recent AMUPOL is more efficient: >200 at 100 K. Such a comparison is valid as long as the signal measured in the absence of microwaves is merely the Boltzmann polarization and is not affected by the spinning of the sample. However, recent MAS-DNP studies at 25 K by Thurber and Tycko (2014) have demonstrated that the presence of nitroxide biradicals combined with sample spinning can lead to a depolarized nuclear state, below the Boltzmann polarization. In this work we demonstrate that TOTAPOL and AMUPOL both lead to observable depolarization at ≈110 K, and that the magnitude of this depolarization is radical dependent. Compared to the static sample, TOTAPOL and AMUPOL lead, respectively, to nuclear polarization losses of up to 20% and 60% at a 10 kHz MAS frequency, while Trityl OX63 does not depolarize at all. This experimental work is analyzed using a theoretical model that explains how the depolarization process works under MAS and gives new insights into the DNP mechanism and into the spin parameters, which are relevant for the efficiency of a biradical. In light of these results, the outstanding performance of AMUPOL must be revised and we propose a new method to assess the polarization gain for future radicals. PMID:26235749

  20. Long-range photon-mediated gate scheme between nuclear spin qubits in diamond

    NASA Astrophysics Data System (ADS)

    Auer, Adrian; Burkard, Guido

    2016-01-01

    Defect centers in diamond are exceptional solid-state quantum systems that can have exceedingly long electron and nuclear spin coherence times. So far, single-qubit gates for the nitrogen nuclear spin, a two-qubit gate with a nitrogen-vacancy (NV) center electron spin, and entanglement between nearby nitrogen nuclear spins have been demonstrated. Here, we develop a scheme to implement a universal two-qubit gate between two distant nitrogen nuclear spins. Virtual excitation of an NV center that is embedded in an optical cavity can scatter a laser photon into the cavity mode; we show that this process depends on the nuclear spin state of the nitrogen atom. If two NV centers are simultaneously coupled to a common cavity mode and individually excited, virtual cavity photon exchange can mediate an effective interaction between the nuclear spin qubits, conditioned on the spin state of both nuclei, which implements a universal controlled-Z gate. We predict operation times below 10 ? s , which is four orders of magnitude faster than the decoherence time of nuclear spin qubits in diamond.

  1. Single-shot readout of multiple nuclear spin qubits in diamond under ambient conditions.

    PubMed

    Drau, A; Spinicelli, P; Maze, J R; Roch, J-F; Jacques, V

    2013-02-01

    We use the electronic spin of a single nitrogen-vacancy defect in diamond to observe the real-time evolution of neighboring single nuclear spins under ambient conditions. Using a diamond sample with a natural abundance of (13)C isotopes, we first demonstrate high fidelity initialization and single-shot readout of an individual (13)C nuclear spin. By including the intrinsic (14)N nuclear spin of the nitrogen-vacancy defect in the quantum register, we then report the simultaneous observation of quantum jumps linked to both nuclear spin species, providing an efficient initialization of the two qubits. These results open up new avenues for diamond-based quantum information processing including active feedback in quantum error correction protocols and tests of quantum correlations with solid-state single spins at room temperature. PMID:23432227

  2. Resolving remote nuclear spins in a noisy bath by dynamical decoupling design

    NASA Astrophysics Data System (ADS)

    Ma, Wenchao; Shi, Fazhan; Xu, Kebiao; Wang, Pengfei; Xu, Xiangkun; Rong, Xing; Ju, Chenyong; Duan, Chang-Kui; Zhao, Nan; Du, Jiangfeng

    2015-09-01

    We experimentally resolve several weakly coupled nuclear spins in diamond using a series of dynamical decoupling controls. Some nuclear spin signals, hidden by decoherence under ordinary dynamical decoupling controls, are shifted forward in time domain to the coherence time range and thus rescued from the fate of being submerged by the noisy spin bath. In this way, more and remote single nuclear spins are resolved. Additionally, the field of detection can be continuously tuned on subnanoscale. This method extends the capacity of nanoscale magnetometry and may be applicable in other systems for high-resolution noise spectroscopy.

  3. Theory of single nuclear spin detection in magnetic resonance force microscopy

    NASA Astrophysics Data System (ADS)

    Chemudupati, Srinivasa; Tsifrinovich, Vladimir

    2008-10-01

    We develop a theory for the measurement of a nuclear spin state in a paramagnetic atom with Oscillating Cantilever-Driven Adiabatic Reversals (OSCAR) in Magnetic Resonance Force Microscopy (MRFM). In this theory, we use a semi-classical approach where the electron-nuclear spin system, with hyperfine interaction, is treated quantum mechanically and the motion of the ferromagnetic particle on the cantilever tip is treated classically. Our computations support the idea of the measurement of a nuclear spin state by detection of a single electron spin.

  4. Temperature dependence of nuclear spin coherence in E u3 + :Y2Si O5

    NASA Astrophysics Data System (ADS)

    Arcangeli, Andrea; Macfarlane, Roger M.; Ferrier, Alban; Goldner, Philippe

    2015-12-01

    We have measured the temperature dependence of the spin-lattice relaxation and dephasing of the two nuclear quadrupole transitions in the 7F0 ground state of 151Eu in yttrium orthosilicate up to 21 K. Spin-lattice relaxation (T1) is dominated by an Orbach process and decoherence comes from 87Y nuclear spin fluctuations at low temperatures and is T1 limited at higher temperatures. The different contributions to relaxation and dephasing are evaluated.

  5. High-fidelity readout and control of a nuclear spin qubit in silicon.

    PubMed

    Pla, Jarryd J; Tan, Kuan Y; Dehollain, Juan P; Lim, Wee H; Morton, John J L; Zwanenburg, Floris A; Jamieson, David N; Dzurak, Andrew S; Morello, Andrea

    2013-04-18

    Detection of nuclear spin precession is critical for a wide range of scientific techniques that have applications in diverse fields including analytical chemistry, materials science, medicine and biology. Fundamentally, it is possible because of the extreme isolation of nuclear spins from their environment. This isolation also makes single nuclear spins desirable for quantum-information processing, as shown by pioneering studies on nitrogen-vacancy centres in diamond. The nuclear spin of a (31)P donor in silicon is very promising as a quantum bit: bulk measurements indicate that it has excellent coherence times and silicon is the dominant material in the microelectronics industry. Here we demonstrate electrical detection and coherent manipulation of a single (31)P nuclear spin qubit with sufficiently high fidelities for fault-tolerant quantum computing. By integrating single-shot readout of the electron spin with on-chip electron spin resonance, we demonstrate quantum non-demolition and electrical single-shot readout of the nuclear spin with a readout fidelity higher than 99.8 percent-the highest so far reported for any solid-state qubit. The single nuclear spin is then operated as a qubit by applying coherent radio-frequency pulses. For an ionized (31)P donor, we find a nuclear spin coherence time of 60 milliseconds and a one-qubit gate control fidelity exceeding 98 percent. These results demonstrate that the dominant technology of modern electronics can be adapted to host a complete electrical measurement and control platform for nuclear-spin-based quantum-information processing. PMID:23598342

  6. Nuclear Spin Dependent Parity Violation in Diatomic Molecules

    NASA Astrophysics Data System (ADS)

    Altuntas, Emine; Ammon, Jeffrey; Cahn, Sidney; Demille, David; Kozlov, Mikhail; Paolino, Richard

    2015-05-01

    Nuclear spin-dependent parity violation (NSD-PV) effects arise from exchange of the Z0 boson between electrons and the nucleus, and from interaction of electrons with the nuclear anapole moment, a parity-odd magnetic moment. The latter scales with nucleon number of the nucleus A as A 2 / 3 , whereas the Z0 coupling is independent of A. Thus the former is the dominant source of NSD-PV for nuclei with A >= 20. We study NSD-PV effects using diatomic molecules, where signals are dramatically amplified by bringing rotational levels of opposite parity close to degeneracy in a strong magnetic field. Using a Stark-interference technique we measure the NSD-PV interaction matrix element. We present results that demonstrate statistical sensitivity to NSD-PV effects surpassing that of any previous atomic parity violation measurement, using the test system 138Ba19F. We also discuss investigations of systematics due to non-reversing stray E-fields, Enr together with B-field inhomogeneities, and short-term prospects for measuring the nuclear anapole moment of 137Ba. In the long term, our technique is sufficiently general and sensitive to enable measurements across a broad range of nuclei.

  7. A 3D-printed high power nuclear spin polarizer.

    PubMed

    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

    2014-01-29

    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 (129)Xe and (1)H 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 (129)Xe 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 (129)Xe polarization exponential build-up rate [(3.63 0.15) 10(-2) min(-1)] and in-cell (129)Xe 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 (129)Xe and Rb (PRb ? 96%). Hyperpolarization-enhanced (129)Xe 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

  8. Antiferromagnetic nuclear spin helix and topological superconductivity in 13C nanotubes

    NASA Astrophysics Data System (ADS)

    Hsu, Chen-Hsuan; Stano, Peter; Klinovaja, Jelena; Loss, Daniel

    2015-12-01

    We investigate the Ruderman-Kittel-Kasuya-Yosida (RKKY) interaction arising from the hyperfine coupling between localized nuclear spins and conduction electrons in interacting 13C carbon nanotubes. Using the Luttinger liquid formalism, we show that the RKKY interaction is sublattice dependent, consistent with the spin susceptibility calculation in noninteracting carbon nanotubes, and it leads to an antiferromagnetic nuclear spin helix in finite-size systems. The transition temperature reaches up to tens of mK, due to a strong boost by a positive feedback through the Overhauser field from ordered nuclear spins. Similar to GaAs nanowires, the formation of the helical nuclear spin order gaps out half of the conduction electrons, and is therefore observable as a reduction of conductance by a factor of 2 in a transport experiment. The nuclear spin helix leads to a density wave combining spin and charge degrees of freedom in the electron subsystem, resulting in synthetic spin-orbit interaction, which induces nontrivial topological phases. As a result, topological superconductivity with Majorana fermion bound states can be realized in the system in the presence of proximity-induced superconductivity without the need of fine tuning the chemical potential. We present the phase diagram as a function of system parameters, including the pairing gaps, the gap due to the nuclear spin helix, and the Zeeman field perpendicular to the helical plane.

  9. 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.

  10. Measurement of untruncated nuclear spin interactions via zero- to ultralow-field nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Blanchard, J. W.; Sjolander, T. F.; King, J. P.; Ledbetter, M. P.; Levine, E. H.; Bajaj, V. S.; Budker, D.; Pines, A.

    2015-12-01

    Zero- to ultralow-field nuclear magnetic resonance (ZULF NMR) provides a new regime for the measurement of nuclear spin-spin interactions free from the effects of large magnetic fields, such as truncation of terms that do not commute with the Zeeman Hamiltonian. One such interaction, the magnetic dipole-dipole coupling, is a valuable source of spatial information in NMR, though many terms are unobservable in high-field NMR, and the coupling averages to zero under isotropic molecular tumbling. Under partial alignment, this information is retained in the form of so-called residual dipolar couplings. We report zero- to ultralow-field NMR measurements of residual dipolar couplings in acetonitrile-2-13C aligned in stretched polyvinyl acetate gels. This permits the investigation of dipolar couplings as a perturbation on the indirect spin-spin J coupling in the absence of an applied magnetic field. As a consequence of working at zero magnetic field, we observe terms of the dipole-dipole coupling Hamiltonian that are invisible in conventional high-field NMR. This technique expands the capabilities of zero- to ultralow-field NMR and has potential applications in precision measurement of subtle physical interactions, chemical analysis, and characterization of local mesoscale structure in materials.

  11. Nuclear spin scissors - new type of collective motion

    NASA Astrophysics Data System (ADS)

    Balbutsev, E. B.; Molodtsova, I. V.

    2014-09-01

    The coupled dynamics of the orbital and spin scissors modes is 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. The relation between our results and the recent experimental data is discussed.

  12. New type of nuclear collective motion: The spin scissors mode

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    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.

  13. Influence of spin polarizability on liquid gas phase transition in the nuclear matter

    NASA Astrophysics Data System (ADS)

    Rezaei, Z.; Bigdeli, M.; Bordbar, G. H.

    2015-10-01

    In this paper, we investigate the liquid gas phase transition for the spin polarized nuclear matter. Applying the lowest order constrained variational (LOCV) method, and using two microscopic potentials, AV18 and UV14+TNI, we calculate the free energy, equation of state (EOS), order parameter, entropy, heat capacity and compressibility to derive the critical properties of spin polarized nuclear matter. Our results indicate that for the spin polarized nuclear matter, the second-order phase transition takes place at lower temperatures with respect to the unpolarized one. It is also shown that the critical temperature of our spin polarized nuclear matter with a specific value of spin polarization parameter is in good agreement with the experimental result.

  14. Spin Responses in Nuclei and Nuclear Weak Processes in Stars

    NASA Astrophysics Data System (ADS)

    Suzuki, Toshio

    2015-04-01

    New shell-model Hamiltonians which can successfuly describe spin-dependent transition rates in nuclei are applied to study nuclear weak processes in stars. New v-induced reaction cross sections in 12C and 56Fe evaluated by the new Hamiltonians are shown to reproduce well the experimental data. Nucleosynthesis of light elements in supernova explosions (SNe) as well as v oscillation effects are discussed with the new cross sections. Electron capture and ?-decay rates in stellar environments are re-evaluated in fp- and sd-shell nuclei. Nucleosynthesis in Type-Ia SNe, rp-process and X-ray burst are discussed with the new reaction rates in Ni isotopes. Important roles of accurate e-capture and ?-decay rates in sd-shell nuclei on the cooling of stars with 8-10 solar masses by nuclear URCA processes and the fate of the stars are demonstrated. ?-decay half-lives of waiting-point nuclei at N =126 are evaluated by shell- model calculations, and r-process nucleosynthesis up to Th and U region in both core-collapse SNe and binary neutron star mergers are studied.

  15. (Evolution of nuclear collectivity at high spins and temperatures)

    SciTech Connect

    Baktash, C.

    1989-09-28

    The traveler attended and presented an invited talk entitled Evolution of nuclear collectivity at high spins and temperatures'' at the XII Workshop on Nuclear Physics at Iguazu Falls, Argentina. Following the conference, the traveler visited the TANDAR Laboratory in Buenos Aires, Argentina, for two weeks. This trip was the first by one of the principal investigators of an ORNL-TANDAR exchange program that was recently approved and funded by the NSF. The results of the extensive consultations that the traveler had with his Argentine collaborators, A. J. Kreiner and G. Garcia-Bermudez, can be summarized as follows: (1) discussed the spectroscopy work on several nuclei of common interest that are being studied at the two laboratories, (2) agreed on the first joint experiments to be performed at the Holifield and TANDAR facilities, (3) developed a tentative timetable for the future visits by both groups, and (4) continued with the analysis of data on {sup 82}Sr taken earlier at ORNL in collaboration with Dr. Garcia-Bermudez.

  16. Room-temperature coupling between electrical current and nuclear spins in OLEDs

    NASA Astrophysics Data System (ADS)

    Malissa, H.; Kavand, M.; Waters, D. P.; van Schooten, K. J.; Burn, P. L.; Vardeny, Z. V.; Saam, B.; Lupton, J. M.; Boehme, C.

    2014-09-01

    The effects of external magnetic fields on the electrical conductivity of organic semiconductors have been attributed to hyperfine coupling of the spins of the charge carriers and hydrogen nuclei. We studied this coupling directly by implementation of pulsed electrically detected nuclear magnetic resonance spectroscopy in organic light-emitting diodes (OLEDs). The data revealed a fingerprint of the isotope (protium or deuterium) involved in the coherent spin precession observed in spin-echo envelope modulation. Furthermore, resonant control of the electric current by nuclear spin orientation was achieved with radiofrequency pulses in a double-resonance scheme, implying current control on energy scales one-millionth the magnitude of the thermal energy.

  17. Recursive polarization of nuclear spins in diamond at arbitrary magnetic fields

    SciTech Connect

    Pagliero, Daniela; Laraoui, Abdelghani; Henshaw, Jacob D.; Meriles, Carlos A.

    2014-12-15

    We introduce an alternate route to dynamically polarize the nuclear spin host of nitrogen-vacancy (NV) centers in diamond. Our approach articulates optical, microwave, and radio-frequency pulses to recursively transfer spin polarization from the NV electronic spin. Using two complementary variants of the same underlying principle, we demonstrate nitrogen nuclear spin initialization approaching 80% at room temperature both in ensemble and single NV centers. Unlike existing schemes, our approach does not rely on level anti-crossings and is thus applicable at arbitrary magnetic fields. This versatility should prove useful in applications ranging from nanoscale metrology to sensitivity-enhanced NMR.

  18. Distal and proximal ligand interactions in heme proteins: Correlations between C-O and Fe-C vibrational frequencies, oxygen-17 and carbon-13 nuclear magnetic resonance chemical shifts, and oxygen-17 nuclear quadrupole coupling constants in C sup 17 O- and sup 13 CO-labeled species

    SciTech Connect

    Ki Deok Park; Guo, K.; Adebodun, F.; Chiu, M.L.; Sligar, S.G.; Oldfield, E. )

    1991-03-05

    The authors have obtained the oxygen-17 nuclear magnetic resonance (NMR) spectra of a variety of C{sup 17}O-labeled heme proteins, including sperm whale (Physeter catodon) myoglobin, two synthetic sperm whale myoglobin mutants (His E7 {yields} Val E7; His E7 {yields} Phe E7), adult human hemoglobin, rabbit (Oryctolagus cuniculus) hemoglobin, horseradish (Cochlearia armoracia) peroxidase isoenzymes A and C, and Caldariomyces fumago chloroperoxidase, in some cases as a function of pH, and have determined their isotropic {sup 17}O NMR chemical shifts, {delta}{sub i}, and spin-lattice relaxation times, T{sub 1}. They have also obtained similar results on a picket fence prophyrin. The results show an excellent correlation between the infrared C-O vibrational frequencies, {nu}(C-O), and {delta}{sub i}, between {nu}(C-O) and the {sup 17}O nuclear quadrupole coupling constant, and as expected between e{sup 2}qQ/h and {delta}{sub i}. The results suggest the IR and NMR measurements reflect the same interaction, which is thought to be primarily the degree of {pi}-back-bonding from Fe d to CO {pi}* orbitals, as outlined previously.

  19. Qubit Control Limited by Spin-Lattice Relaxation in a Nuclear Spin-Free Iron(III) Complex.

    PubMed

    Zadrozny, Joseph M; Freedman, Danna E

    2015-12-21

    High-spin transition metal complexes are of interest as candidates for quantum information processing owing to the tunability of the pairs of MS levels for use as quantum bits (qubits). Thus, the design of high-spin systems that afford qubits with stable superposition states is of primary importance. Nuclear spins are a potent instigator of superposition instability; thus, we probed the Ph4P(+) salt of the nuclear spin-free complex [Fe(C5O5)3](3-) (1) to see if long-lived superpositions were possible in such a system. Continuous-wave and pulsed electron paramagnetic resonance (EPR) spectroscopic measurements reveal a strong EPR transition at X-band that can be utilized as a qubit. However, at 5 K the coherent lifetime, T2, for this resonance is 721(3) ns and decreases rapidly with increasing temperature. Simultaneously, the spin-lattice relaxation time is extremely short, 11.33(1) ?s, at 5 K, and also rapidly decreases with increasing temperature. The coincidence of these two temperature-dependent data sets suggests that T2 in 1 is strongly limited by the short T1. Importantly, these results highlight the need for new design parameters in pursuit of high-spin species with appreciable coherence times. PMID:26650962

  20. 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

  1. Electrically generated nuclear spin polarization in In.04Ga.96As

    NASA Astrophysics Data System (ADS)

    Trowbridge, Christopher; Norman, Benjamin; Kato, Yuichiro K.; Awschalom, David; Sih, Vanessa

    2013-03-01

    The promises of lower power consumption and simple interfacing to magnetic storage has driven interest in the development of spintronics, in which devices could take advantage of electron spin as a means to store, move, and process data. Due to its long lifetime in moderate fields, nuclear polarization could serve as intermediate timescale data storage in both classical spintronic and quantum computation schemes. Here, we investigate the role of nuclear spins in materials with electrically driven spin polarization. The electron spin polarization generated by electrical current in a non-magnetic semiconductor is transferred via dynamic nuclear polarization to the nuclei. The resulting nuclear field is interrogated using Larmor magnetometry. We measure nuclear field as a function of current, applied magnetic field, and temperature. Polarization decay dynamics and the role of nuclei in devices are also discussed.

  2. Nuclear surface properties and spin-orbit potential in a modified derivative coupling model

    NASA Astrophysics Data System (ADS)

    Hua, Guo; Chossy, T. V.; Stocker, W.

    2000-01-01

    Based on the Zimnyi-Moszkowski derivative coupling Lagrangian plus tensor-coupling term, calculations of symmetric semi-infinite nuclear matter and finite nuclei have been performed. Our results show that with increasing tensor coupling the spin-orbit potential is considerably improved, but the surface tension and the surface thickness decrease to values too low compared with experiment. In addition, the effects of the ?-meson mass on nuclear surface properties, on the spin-orbit potential as well as on nuclear binding energies are discussed. No parameter set could be found that leads to good surface properties even if energies and spin-orbit splittings are realistic.

  3. 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.

    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.

  4. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond.

    PubMed

    King, Jonathan P; Jeong, Keunhong; Vassiliou, Christophoros C; Shin, Chang S; Page, Ralph H; Avalos, Claudia E; Wang, Hai-Jing; Pines, Alexander

    2015-01-01

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of (13)C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ?170,000 over thermal equilibrium. The signal of the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. Hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions. PMID:26639147

  5. Room-temperature in situ nuclear spin hyperpolarization from optically pumped nitrogen vacancy centres in diamond

    PubMed Central

    King, Jonathan P.; Jeong, Keunhong; Vassiliou, Christophoros C.; Shin, Chang S.; Page, Ralph H.; Avalos, Claudia E.; Wang, Hai-Jing; Pines, Alexander

    2015-01-01

    Low detection sensitivity stemming from the weak polarization of nuclear spins is a primary limitation of magnetic resonance spectroscopy and imaging. Methods have been developed to enhance nuclear spin polarization but they typically require high magnetic fields, cryogenic temperatures or sample transfer between magnets. Here we report bulk, room-temperature hyperpolarization of 13C nuclear spins observed via high-field magnetic resonance. The technique harnesses the high optically induced spin polarization of diamond nitrogen vacancy centres at room temperature in combination with dynamic nuclear polarization. We observe bulk nuclear spin polarization of 6%, an enhancement of ∼170,000 over thermal equilibrium. The signal of the hyperpolarized spins was detected in situ with a standard nuclear magnetic resonance probe without the need for sample shuttling or precise crystal orientation. Hyperpolarization via optical pumping/dynamic nuclear polarization should function at arbitrary magnetic fields enabling orders of magnitude sensitivity enhancement for nuclear magnetic resonance of solids and liquids under ambient conditions. PMID:26639147

  6. 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

  7. Electrical current and coupled electron-nuclear spin dynamics in double quantum dots

    NASA Astrophysics Data System (ADS)

    Giavaras, G.; Lambert, Neill; Nori, Franco

    2013-03-01

    We examine electronic transport in a spin-blockaded double quantum dot. We show that by tuning the strength of the spin-orbit interaction the current flowing through the double dot exhibits a dip at zero magnetic field or a peak at a magnetic field for which the two-electron energy levels anticross. This behavior is due to the dependence of the singlet-triplet mixing on the field and spin-orbit amplitude. We derive approximate expressions for the current as a function of the amplitudes of the states involved in the transport. We also consider an alternative model that takes into account a finite number of nuclear spins and study the resulting coupled dynamics between electron and nuclear spins. We show that if the spin ensemble is in a thermal state there are regular oscillations in the transient current followed by quasichaotic revivals akin to those seen in a thermal Jaynes-Cummings model.

  8. Cross polarization from spins I =1/2 to spins S =1 in nuclear magnetic resonance with magic angle sample spinning

    NASA Astrophysics Data System (ADS)

    Gopalakrishnan, Karthik; Bodenhausen, Geoffrey

    2006-05-01

    Spin locking of the nuclear magnetization of a spin with S =1 such as deuterium in the presence of a radio-frequency field under magic angle spinning (MAS) is described in terms of adiabatic modulations of the energy levels. In a brief initial period, part of the initial density operator nutates about the Hamiltonian and is dephased. The remaining spin-locked state undergoes persistent oscillatory transfer processes between various coherences with a periodicity given by the rotation of the sample. While all crystallites in the powder undergo such periodic transfer processes, the phases of the oscillations depend on the angle ? of the crystallites. The angle ? is the azimuthal angle defining the orientation of the unique axis of the quadrupolar interaction tensor in a rotor-fixed frame. The theory is extended to describe cross-polarization between spins S =1 and I =1/2 under MAS. There are four distinct Hartmann-Hahn matching conditions that correspond to four zero-quantum matching conditions, all of which are shifted and broadened compared to their spin S =1/2 counterparts. These matching conditions are further split into a family of sideband conditions separated by the spinning frequency. The theory allows the calculation of both shifts and broadening factors of the matching conditions, as verified by simulations and experiments.

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

    NASA Astrophysics Data System (ADS)

    Flix, Gautier; Mikolasek, Mirko; Peng, Haonan; Nicolazzi, William; Molnr, Gbor; 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.

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

    SciTech Connect

    Stuhrmann, H.B.; Nierhaus, K.H.

    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.

  11. Theory of box-model hyperfine couplings and transport signatures of long-range nuclear-spin coherence in a quantum-dot spin valve

    NASA Astrophysics Data System (ADS)

    Chesi, Stefano; Coish, W. A.

    2015-06-01

    We have theoretically analyzed coherent nuclear-spin dynamics induced by electron transport through a quantum-dot spin valve. The hyperfine interaction between electron and nuclear spins in a quantum dot allows for the transfer of angular momentum from spin-polarized electrons injected from ferromagnetic or half-metal leads to the nuclear spin system under a finite voltage bias. Accounting for a local nuclear-spin dephasing process prevents the system from becoming stuck in collective dark states, allowing a large nuclear polarization to be built up in the long-time limit. After reaching a steady state, reversing the voltage bias induces a transient current response as the nuclear polarization is reversed. Long-range nuclear-spin coherence leads to a strong enhancement of spin-flip transition rates (by an amount proportional to the number of nuclear spins) and is revealed by an intense current burst, analogous to superradiant light emission. The crossover to a regime with incoherent spin flips occurs on a relatively long-time scale, on the order of the single-nuclear-spin dephasing time, which can be much longer than the time scale for the superradiant current burst. This conclusion is confirmed through a general master equation. For the two limiting regimes (coherent/incoherent spin flips), the general master equation recovers our simpler treatment based on rate equations, but is also applicable at intermediate dephasing. Throughout this work, we assume uniform hyperfine couplings, which yield the strongest coherent enhancement. We propose realistic strategies, based on isotopic modulation and wave-function engineering in core-shell nanowires, to realize this analytically solvable "box-model" of hyperfine couplings.

  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. Microscopic control of 29Si nuclear spins near phosphorus donors in silicon

    NASA Astrophysics Data System (ADS)

    Jrvinen, J.; Zvezdov, D.; Ahokas, J.; Sheludyakov, S.; Vainio, O.; Lehtonen, L.; Vasiliev, S.; Fujii, Y.; Mitsudo, S.; Mizusaki, T.; Gwak, M.; Lee, SangGap; Lee, Soonchil; Vlasenko, L.

    2015-09-01

    We demonstrate an efficient control of 29Si nuclear spins for specific lattice sites near 31P donors in silicon at temperatures below 1 K and in a high magnetic field of 4.6 T. Excitation of the forbidden electron-nuclear transitions leads to a pattern of well-resolved holes and peaks in the electron spin resonance (ESR) lines of 31P . The pattern originates from dynamic polarization (DNP) of the 29Si nuclear spins near the donors via the solid effect. DNP of 29Si is demonstrated also with the Overhauser effect where the allowed ESR transitions are excited. In this case mostly the remote 29Si nuclei having weak interaction with the donors are polarized, which results in a single hole and a sharp peak pair in the ESR spectrum. Our work shows that the solid effect can be used for initialization of 29Si nuclear spin qubits near the donors.

  14. Knight shift and nuclear spin relaxation in Fe/n -GaAs heterostructures

    NASA Astrophysics Data System (ADS)

    Christie, K. D.; Geppert, C. C.; Patel, S. J.; Hu, Q. O.; Palmstrøm, C. J.; Crowell, P. A.

    2015-10-01

    We investigate the dynamically polarized nuclear spin system in Fe/n -GaAs heterostructures using the response of the electron-spin system to nuclear magnetic resonance (NMR) in lateral spin-valve devices. The hyperfine interaction is known to act more strongly on donor-bound electron states than on those in the conduction band. We provide a quantitative model of the temperature dependence of the occupation of donor sites. With this model we calculate the ratios of the hyperfine and quadrupolar nuclear relaxation rates of each isotope. For all temperatures measured, quadrupolar relaxation limits the spatial extent of nuclear spin polarization to within a Bohr radius of the donor sites and is directly responsible for the isotope dependence of the measured NMR signal amplitude. The hyperfine interaction is also responsible for the 2 kHz Knight shift of the nuclear resonance frequency that is measured as a function of the electron-spin accumulation. The Knight shift is shown to provide a measurement of the electron-spin polarization that agrees qualitatively with standard spin transport measurements.

  15. Nuclear spin-polarized fuel in inertial fusion

    SciTech Connect

    More, R.M.

    1983-08-01

    This Letter examines the possibility of using spin-polarized DT fuel for inertial-confinement fusion. Analytic models and estimates are developed to determine whether an initial spin-polarized state would survive target irradiation and implosion. It is found that collisional depolarization cross sections are not large enough to give significant depolarization, and that the short duration of inertial-fusion implosions precludes spin resonance for magnetic fields that can be reasonably expected in the target fuel.

  16. Nuclear Spin-Polarized Fuel in Inertial Fusion

    NASA Astrophysics Data System (ADS)

    More, Richard M.

    1983-08-01

    This Letter examines the possibility of using spin-polarized DT fuel for inertial-confinement fusion. Analytic models and estimates are developed to determine whether an initial spin-polarized state would survive target irradiation and implosion. It is found that collisional depolarization cross sections are not large enough to give significant depolarization, and that the short duration of inertial-fusion implosions precludes spin resonance for magnetic fields that can be reasonably expected in the target fuel.

  17. Description of 158Er at Ultrahigh Spin in Nuclear Density Functional Theory

    SciTech Connect

    Afanasjev, A. V.; Nazarewicz, Witold

    2012-01-01

    Rotational bands in 158Er at ultrahigh spin have been studied in the framework of relativistic and nonrelativistic nuclear density-functional theories. Consistent results are obtained across the theoretical models used but some puzzles remain when confronted with experiment. Namely, the many-body configurations which provide good description of experimental transition quadrupole moments and dynamic moments of inertia require substantial increase of the spins of observed bands as compared with experimental estimates, which are still subject to large uncertainties. If, however, the theoretical spin assignments turned out to be correct, experimental band 1 in 158Er would be the highest spin structure ever observed.

  18. Probing a single nuclear spin in a silicon single electron transistor

    NASA Astrophysics Data System (ADS)

    Delgado, F.; Aguado, R.; Fernndez-Rossier, J.

    2012-08-01

    We study single electron transport across a single Bi dopant in a silicon nanotransistor to assess how the strong hyperfine coupling with the Bi nuclear spin I = 9/2 affects the transport characteristics of the device. In the sequential tunneling regime we find that at, temperatures in the range of 100 mK, dI/dV curves reflect the zero field hyperfine splitting as well as its evolution under an applied magnetic field. Our non-equilibrium quantum simulations show that nuclear spins can be partially polarized parallel or antiparallel to the electronic spin just tuning the applied bias.

  19. Classical nature of nuclear spin noise near clock transitions of Bi donors in silicon

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

    Whether a quantum bath can be approximated as classical Gaussian noise is a fundamental issue in central spin decoherence and also of practical importance in designing noise-resilient quantum control. Spin qubits based on bismuth donors in silicon have tunable interactions with nuclear spin baths and are first-order insensitive to magnetic noise at so-called clock transitions (CTs). This system is therefore ideal for studying the quantum/classical Gaussian nature of nuclear spin baths since the qubit-bath interaction strength determines the back-action on the baths and hence the adequacy of a Gaussian noise model. We develop a Gaussian noise model with noise correlations determined by quantum calculations and compare the classical noise approximation to the full quantum bath theory. We experimentally test our model through a dynamical decoupling sequence of up to 128 pulses, finding good agreement with simulations and measuring electron spin coherence times approaching 1 snotably using natural silicon. Our theoretical and experimental study demonstrates that the noise from a nuclear spin bath is analogous to classical Gaussian noise if the back-action of the qubit on the bath is small compared to the internal bath dynamics, as is the case close to CTs. However, far from the CTs, the back-action of the central spin on the bath is such that the quantum model is required to accurately model spin decoherence.

  20. Spin Noise Detection of Nuclear Hyperpolarization at 1.2?K.

    PubMed

    Pschko, Maria Theresia; Vuichoud, Basile; Milani, Jonas; Bornet, Aurlien; Bechmann, Matthias; Bodenhausen, Geoffrey; Jannin, Sami; Mller, Norbert

    2015-12-01

    We report proton spin noise spectra of a hyperpolarized solid sample of commonly used "DNP (dynamic nuclear polarization) juice" containing TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide) and irradiated by a microwave field at a temperature of 1.2?K in a magnetic field of 6.7?T. The line shapes of the spin noise power spectra are sensitive to the variation of the microwave irradiation frequency and change from dip to bump, when the electron Larmor frequency is crossed, which is shown to be in good accordance with theory by simulations. Small but significant deviations from these predictions are observed, which can be related to spin noise and radiation damping phenomena that have been reported in thermally polarized systems. The non-linear dependence of the spin noise integral on nuclear polarization provides a means to monitor hyperpolarization semi-quantitatively without any perturbation of the spin system by radio frequency irradiation. PMID:26477605

  1. Coupling and control in coherently driven and asymmetrically synchronized hybrid electron-nuclear spin system

    NASA Astrophysics Data System (ADS)

    Berec, V.

    2016-02-01

    We study the coupling and control adaptation of a hybrid electron-nuclear spin system using the laser mediated proton beam in MeV energy regime. The asymmetric control mechanism is based on exact optimization of both: the measure of exchange interaction and anisotropy of the hyperfine interaction induced in the resonance with optimal channeled protons (CP) superfocused field, allowing manipulation over arbitrary localized spatial centers while addressing only the electron spin. Using highly precise and coherent proton channeling regime we have obtained efficient pulse shaping separator technique aimed for spatio-temporal engineering of quantum states, introducing a method for control of nuclear spins, which are coupled via anisotropic hyperfine interactions in isolated electron spin manifold, without radio wave (RW) pulses. The presented method can be efficiently implemented in synchronized spin networks with the purpose to facilitate preservation and efficient transfer of experimentally observed quantum particle states, contributing to the overall background noise reduction.

  2. High temperature spin dynamics in linear magnetic chains, molecular rings, and segments by nuclear magnetic resonance

    SciTech Connect

    Adelnia, Fatemeh; Lascialfari, Alessandro; Mariani, Manuel; Ammannato, Luca; Caneschi, Andrea; Rovai, Donella; Winpenny, Richard; Timco, Grigore; Corti, Maurizio Borsa, Ferdinando

    2015-05-07

    We present the room temperature proton nuclear magnetic resonance (NMR) nuclear spin-lattice relaxation rate (NSLR) results in two 1D spin chains: the Heisenberg antiferromagnetic (AFM) Eu(hfac){sub 3}NITEt and the magnetically frustrated Gd(hfac){sub 3}NITEt. The NSLR as a function of external magnetic field can be interpreted very well in terms of high temperature spin dynamics dominated by a long time persistence of the decay of the two-spin correlation function due to the conservation of the total spin value for isotropic Heisenberg chains. The high temperature spin dynamics are also investigated in Heisenberg AFM molecular rings. In both Cr{sub 8} closed ring and in Cr{sub 7}Cd and Cr{sub 8}Zn open rings, i.e., model systems for a finite spin segment, an enhancement of the low frequency spectral density is found consistent with spin diffusion but the high cut-off frequency due to intermolecular anisotropic interactions prevents a detailed analysis of the spin diffusion regime.

  3. 29Si nuclear spin relaxation in microcrystals of plastically deformed Si: B samples

    NASA Astrophysics Data System (ADS)

    Koplak, O. V.; Morgunov, R. B.

    2016-02-01

    Single crystals and microcrystals Si: B enriched with 29Si isotopes have been studied using nuclear magnetic resonance and electron paramagnetic resonance (EPR) in the temperature range from 300 to 800 K. It has been found that an increase in the temperature from 300 to 500 K leads to a change in the kinetics of the relaxation of the saturated nuclear spin system. At 300 K, the relaxation kinetics corresponds to direct electron-nuclear interaction with inhomogeneously distributed paramagnetic centers introduced by the plastic deformation of the crystals. At 500 K, the spin relaxation occurs through the nuclear spin diffusion and electron-nuclear interaction with an acceptor impurity. It has been revealed that the plastic deformation affects the EPR spectra at 9 K.

  4. Strongly polarizing weakly coupled 13C nuclear spins with optically pumped nitrogen-vacancy center

    PubMed Central

    Wang, Ping; Liu, Bao; Yang, Wen

    2015-01-01

    Enhancing the polarization of nuclear spins surrounding the nitrogen-vacancy (NV) center in diamond has recently attracted widespread attention due to its various applications. Here we present an analytical formula that not only provides a clear physical picture for the recently observed polarization reversal of strongly coupled13C nuclei over a narrow range of magnetic field [H. J. Wang et al., Nat. Commun. 4, 1940 (2013)], but also demonstrates the possibility to strongly polarize weakly coupled13C nuclei. This allows sensitive magnetic field control of the 13C nuclear spin polarization for NMR applications and significant suppression of the 13C nuclear spin noise to prolong the NV spin coherence time. PMID:26521962

  5. Strongly polarizing weakly coupled (13)C nuclear spins with optically pumped nitrogen-vacancy center.

    PubMed

    Wang, Ping; Liu, Bao; Yang, Wen

    2015-01-01

    Enhancing the polarization of nuclear spins surrounding the nitrogen-vacancy (NV) center in diamond has recently attracted widespread attention due to its various applications. Here we present an analytical formula that not only provides a clear physical picture for the recently observed polarization reversal of strongly coupled(13)C nuclei over a narrow range of magnetic field [H. J. Wang et al., Nat. Commun. 4, 1940 (2013)], but also demonstrates the possibility to strongly polarize weakly coupled (13)C nuclei. This allows sensitive magnetic field control of the (13)C nuclear spin polarization for NMR applications and significant suppression of the (13)C nuclear spin noise to prolong the NV spin coherence time. PMID:26521962

  6. Strongly polarizing weakly coupled 13C nuclear spins with optically pumped nitrogen-vacancy center

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Liu, Bao; Yang, Wen

    2015-11-01

    Enhancing the polarization of nuclear spins surrounding the nitrogen-vacancy (NV) center in diamond has recently attracted widespread attention due to its various applications. Here we present an analytical formula that not only provides a clear physical picture for the recently observed polarization reversal of strongly coupled13C nuclei over a narrow range of magnetic field [H. J. Wang et al., Nat. Commun. 4, 1940 (2013)], but also demonstrates the possibility to strongly polarize weakly coupled13C nuclei. This allows sensitive magnetic field control of the 13C nuclear spin polarization for NMR applications and significant suppression of the 13C nuclear spin noise to prolong the NV spin coherence time.

  7. Electron spin coherence and electron nuclear double resonance of Bi donors in natural Si

    NASA Astrophysics Data System (ADS)

    Morton, John; Simmons, Stephanie; George, Richard; Witzel, Wayne; Riemann, H.; Abrosimov, Nikolai; Notzel, N.; Thewalt, Mike

    2011-03-01

    We have shown that the electron spin coherence times of Si:Bi donors in natural silicon are limited by the same mechanism of spectral diffusion as seen in Si:P, though the smaller Bohr radius of the Bi donor leads to ~ 30 % longer T2 times (up to 0.8~ms). We have mapped out the 36 ENDOR transitions observable at X-band arising from the I = 9 / 2 nuclear spin of 209 Bi, going up to 1.3~GHz. We also demonstrate the transfer of electron spin coherence to and from the 209 Bi nuclear spin with a fidelity of ~ 63 % . Using pulsed ESR at W-band (100~GHz), we observe optically-induced dynamic nuclear polarisation, consistent with the mechanism of exciton capture proposed in by T. Sekiguchi et al.. Finally, we explore the zero-field splitting of 7.5~GHz in this system, within the context of coupling to superconducting resonators.

  8. Theory of nuclear spin dephasing and relaxation by optically illuminated nitrogen-vacancy center

    NASA Astrophysics Data System (ADS)

    Wang, Ping; Yang, Wen

    2015-11-01

    Dephasing and relaxation of the nuclear spins coupled to the nitrogen-vacancy (NV) center during optical initialization and readout is an important issue for various applications of this hybrid quantum register. Here we present both an analytical description and a numerical simulation for this process, which agree reasonably with the experimental measurements. For an NV center under cyclic optical transition, our analytical formulas not only provide a clear physical picture, but also allow control of the nuclear spin dissipation by tuning an external magnetic field. For more general optical pumping, our analytical formulas reveal a significant contribution to the nuclear spin dissipation due to electron random hopping into/out of the m = 0 (or m=+/- 1) subspace. This contribution is not suppressed, even under saturated optical pumping and/or vanishing magnetic field, thus providing a possible solution to the puzzling observation of nuclear spin dephasing in zero perpendicular magnetic field Dutt et al (2007 Science 316 1312). It also implies that enhancing the degree of optical spin polarization of the nitrogen-vacancy center can reduce the effect of optically induced nuclear spin dissipation.

  9. Testing for parity violation in nuclei using spin density matrices for nuclear density functionals

    NASA Astrophysics Data System (ADS)

    Barrett, B. R.; Giraud, B. G.

    2015-06-01

    The spin density matrix (SDM) used in atomic and molecular physics is revisited for nuclear physics, in the context of the radial density functional theory. The vector part of the SDM defines a hedgehog situation, which exists only if nuclear states contain some amount of parity violation. A toy model is given as an illustrative example.

  10. Nuclear spin-spin coupling anisotropy in the van der Waals-bonded 129Xe dimer.

    PubMed

    Jokisaari, Jukka; Vaara, Juha

    2013-07-21

    The spin-spin coupling constant, J, in the van der Waals-bonded (129)Xe-(129)Xe dimer cannot be determined experimentally because of the magnetic equivalence of the two nuclei. In contrast, the anisotropy of the coupling tensor, ΔJ, can be obtained from the so called effective dipole-dipole coupling determined in a solid state inclusion compound whose cages accommodate two xenon atoms. For the determination of the experimental ΔJ((129)Xe, (129)Xe) we exploited the data reported earlier in this journal. [D. H. Brouwer et al., Phys. Chem. Chem. Phys., 2007, 9, 1093.] The experimental value and the value obtained from relativistic first-principles computation are in perfect agreement. To the best of our knowledge this is the first investigation of spin-spin coupling anisotropy in a van der Waals-bonded system. PMID:23743998

  11. Spin-dependent structure functions in nuclear matter and the polarized EMC effect.

    PubMed

    Clot, I C; Bentz, W; Thomas, A W

    2005-07-29

    An excellent description of both spin-independent and spin-dependent quark distributions and structure functions has been obtained with a modified Nambu--Jona-Lasinio model, which is free of unphysical thresholds for nucleon decay into quarks--hence incorporating an important aspect of confinement. We utilize this model to investigate nuclear medium modifications to structure functions and find that we are readily able to reproduce both nuclear matter saturation and the experimental F2N(A)/F2N ratio, that is, the European Muon Collaboration (EMC) effect. Applying this framework to determine g1p(A), we find that the ratio g1p(A)/g1p differs significantly from unity, with the quenching caused by the nuclear medium being about twice that of the spin-independent case. This represents an exciting result, which, if confirmed experimentally, will reveal much about the quark structure of nuclear matter. PMID:16090869

  12. Nuclear spin dynamics in double quantum dots: Multistability, dynamical polarization, criticality, and entanglement

    NASA Astrophysics Data System (ADS)

    Schuetz, M. J. A.; Kessler, E. M.; Vandersypen, L. M. K.; Cirac, J. I.; Giedke, G.

    2014-05-01

    We theoretically study the nuclear spin dynamics driven by electron transport and hyperfine interaction in an electrically defined double quantum dot 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.

  13. Coherent Storage of Microwave Excitations in Rare-Earth Nuclear Spins

    NASA Astrophysics Data System (ADS)

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

    2015-05-01

    Interfacing between various elements of a computerfrom memory to processors to long range communicationwill be as critical for quantum computers as it is for classical computers today. Paramagnetic rare-earth doped crystals, such as Nd3 +?Y2SiO5 (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 Nd 145 nuclear spin states in Nd3 +?YSO . We find nuclear spin coherence times can reach 9 ms at 5 K , about 2 orders of magnitude longer than the electron spin coherence, while quantum state and process tomography of the storage or retrieval operation between the electron and nuclear spin 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.

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

    PubMed

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

    2015-05-01

    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+):Y2SiO5(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 ?5??K, about 2 orders of magnitude longer than the electron spin coherence, while quantum state and process tomography of the storage or retrieval operation between the electron and nuclear spin 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. PMID:25978214

  15. High-selectivity detection of single nuclear spins using rotary echo on a nitrogen-vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Mkhitaryan, Vagharsh; Dobrovitski, Viatcheslav

    2014-03-01

    The properties of the nitrogen-vacancy (NV) centers in diamond make them an excellent tool for nanoscale spin detection and sensing, capable of detecting individual nuclear spins located 0.5-1 nm away. However, the selectivity of the current methods is limited. We show that the rotating-frame control of the NV center's electron spin can improve the sensing selectivity 10-1000 times in comparison with the existing methods. We employ periodically changing Rabi driving (multiple rotary echo) with a precisely chosen period, corresponding to the precession of the given nuclear spin. The rotary echo decouples the NV center from most nuclear spins, efficiently protecting coherence. At the same time, the given nuclear spin, whose precession fits a stringent resonance condition, does not decouple, and can be detected by its decohering impact on the NV spin. We evaluate the resolution and sensitivity of this detection scheme analytically, and verify the results by numerical simulations.

  16. Interfacing nuclear spins in quantum dots to a cavity or traveling-wave fields

    NASA Astrophysics Data System (ADS)

    Schwager, Heike; Cirac, J. Ignacio; Giedke, Gza

    2010-04-01

    In this paper, we show how to realize a quantum interface between optical fields and the polarized nuclear spins in a singly charged quantum dot, which is strongly coupled to a high-finesse optical cavity. Effective direct coupling between cavity and nuclear spins is obtained by adiabatically eliminating the (far detuned) excitonic and electronic states. The requirements for mapping qubit and continuous variable states of cavity or traveling-wave fields to the collective nuclear spin are investigated: for cavity fields, we consider adiabatic passage processes to transfer the states. It is seen that a significant improvement in cavity lifetimes beyond present-day technology would be required for a quantum interface. We then turn to a scheme that couples the nuclei to the output field of the cavity and does not require a long-lived cavity. We show that the lifetimes reported in the literature and the recently achieved nuclear polarization of ~90% allow both high-fidelity read-out and write-in of quantum information between the nuclear spins and the output field. We discuss the performance of the scheme and provide a convenient description of the dipolar dynamics of the nuclei for highly polarized spins, demonstrating that this process does not affect the performance of our protocol.

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

    SciTech Connect

    Thurber, Kent R. Tycko, Robert

    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.

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

    PubMed Central

    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

  19. Detection and Manipulation of the Statistical Fluctuations in Nuclear Spin Ensembles Using Magnetic Resonance Force Microscopy

    NASA Astrophysics Data System (ADS)

    Mamin, H. J.

    2005-03-01

    We have detected and manipulated the naturally occurring ?N statistical polarization in nuclear spin ensembles using MRFM. We have studied fluorine nuclei in CaF2, as well as protons in the polymer PMMA and the protein collagen. The ensembles studied contained of order 10^8 nuclear spins, corresponding to volumes of order (200nm)^3, which resulted in statistical polarizations of order 10^4 net spins. We have also implemented a scheme similar to one proposed by Weitekamp et al, in which we suppressed the effect of the statistical uncertainty so as to extract meaningful information from time-averaged measurements. In this way, we have successfully made nutation and transverse spin relaxation measurements in a nominally unpolarized sample of CaF2 at low temperatures.

  20. Organic electronics. Room-temperature coupling between electrical current and nuclear spins in OLEDs.

    PubMed

    Malissa, H; Kavand, M; Waters, D P; van Schooten, K J; Burn, P L; Vardeny, Z V; Saam, B; Lupton, J M; Boehme, C

    2014-09-19

    The effects of external magnetic fields on the electrical conductivity of organic semiconductors have been attributed to hyperfine coupling of the spins of the charge carriers and hydrogen nuclei. We studied this coupling directly by implementation of pulsed electrically detected nuclear magnetic resonance spectroscopy in organic light-emitting diodes (OLEDs). The data revealed a fingerprint of the isotope (protium or deuterium) involved in the coherent spin precession observed in spin-echo envelope modulation. Furthermore, resonant control of the electric current by nuclear spin orientation was achieved with radiofrequency pulses in a double-resonance scheme, implying current control on energy scales one-millionth the magnitude of the thermal energy. PMID:25237097

  1. 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

  2. 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.

  3. Mechanism for nuclear and electron spin excitation by radio frequency current

    NASA Astrophysics Data System (ADS)

    Müllegger, Stefan; Rauls, Eva; Gerstmann, Uwe; Tebi, Stefano; Serrano, Giulia; Wiespointner-Baumgarthuber, Stefan; Schmidt, Wolf Gero; Koch, Reinhold

    2015-12-01

    Recent radio frequency scanning tunneling spectroscopy (rf-STS) experiments have demonstrated nuclear and electron spin excitations up to ±12 ℏ in a single molecular spin quantum dot (qudot). Despite the profound experimental evidence, the observed independence of the well-established dipole selection rules is not described by existing theory of magnetic resonance—pointing to a new excitation mechanism. Here we solve the puzzle of the underlying mechanism by discussing the relevant mechanistic steps. At the heart of the mechanism, periodic transient charging and electric polarization due to the rf-modulated tunneling process cause a periodic asymmetric deformation of the adsorbed qudot, enabling efficient spin transitions via spin-phonon-like coupling. The mechanism has general relevance for a broad variety of different spin qudots exhibiting internal mechanical degrees of freedom (organic molecules, doped semiconductor qudots, nanocrystals, etc.).

  4. Nanoscale torsional resonator for polarization and spectroscopy of nuclear spins.

    PubMed

    Butler, Mark C; Norton, Valerie A; Weitekamp, Daniel P

    2010-10-22

    We propose a torsional resonator that couples to the transverse spin dipole of an attached sample. The absence of relative motion eliminates a source of friction that would otherwise hinder nanoscale implementation. Enhanced spontaneous emission induced by the resonator relaxes the longitudinal spin dipole at a rate of ?1??s? in the low-temperature limit. With signal averaging, single-proton magnetic resonance spectroscopy appears feasible at ?10??mK and a high magnetic field, while single-shot sensitivity is practical for samples with at least tens of protons in a volume of ?5??nm. PMID:21231080

  5. 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

  6. Dynamics of nuclear spin measurement in a mesoscopic solid-state quantum computer

    NASA Astrophysics Data System (ADS)

    Berman, Gennady P.; Campbell, David K.; Doolen, Gary D.; Nagaev, Kirill E.

    2000-04-01

    We study numerically the process of nuclear spin measurement in a solid-state quantum computer of the type proposed by Kane, by calculating the quantum dynamics of two coupled nuclear spins on 31 P donors implanted in 28 Si. We estimate the time of the `quantum swap operation' - the minimum measurement time required for the reliable transfer of quantum information from the nuclear spin subsystem to the electronic subsystem. Our calculations show that for realistic values of the parameters this time is of the order of icons/Journals/Common/tau" ALT="tau" ALIGN="TOP"/> swap ~5 10-5 s. We also calculate the probability of error for typical values of the external noise.

  7. Interaction of Strain and Nuclear Spins in Silicon: Quadrupolar Effects on Ionized Donors

    NASA Astrophysics Data System (ADS)

    Franke, David P.; Hrubesch, Florian M.; Knzl, Markus; Becker, Hans-Werner; Itoh, Kohei M.; Stutzmann, Martin; Hoehne, Felix; Dreher, Lukas; Brandt, Martin S.

    2015-07-01

    The nuclear spins of ionized donors in silicon have become an interesting quantum resource due to their very long coherence times. Their perfect isolation, however, comes at a price, since the absence of the donor electron makes the nuclear spin difficult to control. We demonstrate that the quadrupolar interaction allows us to effectively tune the nuclear magnetic resonance of ionized arsenic donors in silicon via strain and determine the two nonzero elements of the S tensor linking strain and electric field gradients in this material to S11=1.5 1022 V /m2 and S44=6 1022 V /m2 . We find a stronger benefit of dynamical decoupling on the coherence properties of transitions subject to first-order quadrupole shifts than on those subject to only second-order shifts and discuss applications of quadrupole physics including mechanical driving of magnetic resonance, cooling of mechanical resonators, and strain-mediated spin coupling.

  8. Nuclear-Spin Selection Rules in the Chemistry of Interstellar Nitrogen Hydrides

    NASA Astrophysics Data System (ADS)

    Rist, Claire; Faure, Alexandre; Hily-Blant, Pierre; Le Gal, Romane

    2013-10-01

    Nitrogen hydrides are at the root of the nitrogen chemistry in interstellar space. The detailed modeling of their gas phase formation, however, requires the knowledge of nuclear-spin branching ratios for chemical reactions involving multiprotonated species. We investigate in this work the nuclear-spin selection rules in both exothermic and near thermoneutral ion-molecule reactions involved in the synthesis of ammonia, assuming full scrambling of protons in the reaction complexes. The formalism of Oka [ J. Mol. Spectrosc. 2004, 228, 635 ] is employed for highly exothermic ion-molecule and dissociative recombination reactions. For thermoneutral reactions, a simple state-to-state statistical approach is suggested, which is in qualitative agreement with both quantum scattering and microcanonical statistical calculations. This model is applied to the seven atom reaction NH4+ + H2, of possible importance in the nuclear-spin thermalization of ammonia.

  9. Nuclear-spin selection rules in the chemistry of interstellar nitrogen hydrides.

    PubMed

    Rist, Claire; Faure, Alexandre; Hily-Blant, Pierre; Le Gal, Romane

    2013-10-01

    Nitrogen hydrides are at the root of the nitrogen chemistry in interstellar space. The detailed modeling of their gas phase formation, however, requires the knowledge of nuclear-spin branching ratios for chemical reactions involving multiprotonated species. We investigate in this work the nuclear-spin selection rules in both exothermic and near thermoneutral ionmolecule reactions involved in the synthesis of ammonia, assuming full scrambling of protons in the reaction complexes. The formalism of Oka [ J. Mol. Spectrosc. 2004, 228, 635] is employed for highly exothermic ionmolecule and dissociative recombination reactions. For thermoneutral reactions, a simple state-to-state statistical approach is suggested, which is in qualitative agreement with both quantum scattering and microcanonical statistical calculations. This model is applied to the seven atom reaction NH4(+) + H2, of possible importance in the nuclear-spin thermalization of ammonia. PMID:23461639

  10. Vector Model Of Electron Spin Echo Envelope Modulation Due To Nuclear Hyperfine And Zeeman Interactions

    SciTech Connect

    Maryasov, Alexander G.; Bowman, Michael K. ); Tsvetkov, Yuri D.

    2002-12-01

    The transverse electron spin magnetization of a paramagnetic center with effective spin S=? interacting with nonquadrupolar nuclei may be presented as a function of pairs of nuclei magnetization vectors which process around the effective magnetic field directions. Each vector of the pair starts its precession perpendicular to both effective fields. The FID signal is proportional to the scalar product of the vectors for nuclear spin I=?. The ESE signal can be described using two pairs of magnetization vectors. The ESE shape is not equal to two back-to-back FID signals except in the absence of ESE envelope modulation. A recursion relation is obtained which allows calculation of ESE signals for larger nuclear spins in the absence of NQI. This relation can be used to calculate the time course of the ESE signal for arbitrary nuclear spin as a function of the nuclear magnetization vectors. Although this formalism allows quantitative calculation of modulation from nuclei, it also provides a qualitative means of visualizing the modulation based on simple magnetization vectors.

  11. 93Nb Nuclear Spin-Spin Relaxation in the Low-Dimensional Antiferromagnet Fe0.25NbS2

    NASA Astrophysics Data System (ADS)

    Okubo, Noriaki

    2007-11-01

    93Nb nuclear spin-spin relaxation has been examined in the low-dimensional antiferromagnet Fe0.25NbS2 between 4.2 K and 300 K. The relaxation is characterized by two T2's. The temperature dependence is discussed together with the origin of the disappearance of the fast decay at low temperatures.

  12. 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.

  13. Effect of nuclear spin symmetry in cold and ultracold reactions: D + para/ortho-H2

    NASA Astrophysics Data System (ADS)

    Simbotin, Ionel; Ct, Robin

    2015-06-01

    We report results for reaction and vibrational quenching of the collision D with para-H2(v,j=0) and ortho-H2(v,j=1) at cold and ultracold temperatures. We investigate the effect of nuclear spin symmetry for barrier dominated processes (0?slant v?slant 4) and for one barrierless case (v = 5). We find resonant structures for energies in the range corresponding to 0.01-10 K, which depend on the nuclear spin of H2, arising from contributions of specific partial waves. We discuss the implications on the results in this benchmark system for ultracold chemistry.

  14. Relativistic Force Field: Parametrization of (13)C-(1)H Nuclear Spin-Spin Coupling Constants.

    PubMed

    Kutateladze, Andrei G; Mukhina, Olga A

    2015-11-01

    Previously, we reported a reliable DU8 method for natural bond orbital (NBO)-aided parametric scaling of Fermi contacts to achieve fast and accurate prediction of proton-proton spin-spin coupling constants (SSCC) in (1)H NMR. As sophisticated NMR experiments for precise measurements of carbon-proton SSCCs are becoming more user-friendly and broadly utilized by the organic chemistry community to guide and inform the process of structure determination of complex organic compounds, we have now developed a fast and accurate method for computing (13)C-(1)H SSCCs. Fermi contacts computed with the DU8 basis set are scaled using selected NBO parameters in conjunction with empirical scaling coefficients. The method is optimized for inexpensive B3LYP/6-31G(d) geometries. The parametric scaling is based on a carefully selected training set of 274 ((3)J), 193 ((2)J), and 143 ((1)J) experimental (13)C-(1)H spin-spin coupling constants reported in the literature. The DU8 basis set, optimized for computing Fermi contacts, which by design had evolved from optimization of a collection of inexpensive 3-21G*, 4-21G, and 6-31G(d) bases, offers very short computational (wall) times even for relatively large organic molecules containing 15-20 carbon atoms. The most informative SSCCs for structure determination, i.e., (3)J, were computed with an accuracy of 0.41 Hz (rmsd). The new unified approach for computing (1)H-(1)H and (13)C-(1)H SSCCs is termed "DU8c". PMID:26414291

  15. Inhomogeneous nuclear spin polarization induced by helicity-modulated optical excitation of fluorine-bound electron spins in ZnSe

    NASA Astrophysics Data System (ADS)

    Heisterkamp, F.; Greilich, A.; Zhukov, E. A.; Kirstein, E.; Kazimierczuk, T.; Korenev, V. L.; Yugova, I. A.; Yakovlev, D. R.; Pawlis, A.; Bayer, M.

    2015-12-01

    Optically induced nuclear spin polarization in a fluorine-doped ZnSe epilayer is studied by time-resolved Kerr rotation using resonant excitation of donor-bound excitons. Excitation with helicity-modulated laser pulses results in a transverse nuclear spin polarization, which is detected as a change of the Larmor precession frequency of the donor-bound electron spins. The frequency shift in dependence on the transverse magnetic field exhibits a pronounced dispersion-like shape with resonances at the fields of nuclear magnetic resonance of the constituent zinc and selenium isotopes. It is studied as a function of external parameters, particularly of constant and radio frequency external magnetic fields. The width of the resonance and its shape indicate a strong spatial inhomogeneity of the nuclear spin polarization in the vicinity of a fluorine donor. A mechanism of optically induced nuclear spin polarization is suggested based on the concept of resonant nuclear spin cooling driven by the inhomogeneous Knight field of the donor-bound electron.

  16. Nuclear Spin Relaxation Characteristic of Submonolayer He Films in Nanochannels

    NASA Astrophysics Data System (ADS)

    Matsushita, Taku; Kawai, Ryosuke; Kuze, Atsushi; Hieda, Mitsunori; Wada, Nobuo

    2014-04-01

    In order to obtain information on dynamics of helium films in the nondegenerate fluid region, we have performed a pulsed-NMR experiment at 3.29 MHz on He films adsorbed in straight 2.4 nm channels of FSM silicates down to 0.54 K. In general, the spin-lattice and spin-spin relaxation times and were explained in terms of the two-dimensional Bloembergen-Purcell-Pound model for dipolar relaxation. Temperature dependences of in submonolayer He films show a minimum, indicating that the dipolar-field correlation time is about s. The temperature of the minimum monotonically lowers with increasing coverage, suggesting that He adatoms become more mobile at higher coverages. The low-dimensional property of He adatoms is observed as the separation of and above where . On the other hand, several features specific to films in the nanochannel geometry were also found. Especially, the temperature dependence of becomes very small just below and shows a shoulder at lower temperatures. This anomaly has not been observed in He adsorbed in wider pores or on flat surfaces, so that it is considered to be characteristic of He films confined in narrow channels with a diameter of a few nm.

  17. NMR Investigation of Optical Polarization of Nuclear Spins in GaAs

    NASA Astrophysics Data System (ADS)

    Paravastu, Anant; Hayes, Sophia; Schwickert, Birgit; Reimer, Jeffrey; Dinh, Long; Balooch, Mehdi

    2003-03-01

    Light-induced nuclear spin alignments have been measured in GaAs as a function of photon energy, irradiation time, and sample temperature using NMR spectroscopy at 9.4 Tesla and 10 to 50 K. Significant optical enhancements were observed at a range of photon energies, starting just below the band gap and persisting through 100 meV above the gap. Irradiation above the band gap resulted in thermally activated NMR signal enhancements while sub band gap irradiation did not. Short and long irradiation time dependencies revealed insights into the nature of cross relaxation between electronic nuclear spins, contradicting mechanisms based on either localized electron-nuclear contact at defect sites or cross relaxation between nuclei and free electrons. We propose that the presence of a mobile or delocalized enabling electronic species characterized by a long electron-nuclear correlation time, such as an exciton, is necessary in any mechanism which explains the data.

  18. Two-dimensional NMR studies of staphylococcal nuclease: Evidence for conformational heterogeneity from hydrogen-1, carbon-13, and nitrogen-15 spin systems assignments of the aromatic amino acids in 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. )

    1990-05-01

    A combination of multinuclear two-dimensional NMR experiments served to identify and assign the combined {sup 1}H, {sup 13}C, and {sup 15}N spin systems of the single tryptophan, three phenylalanines, three histidines, and seven tyrosines of staphylococcal nuclease H124L in its ternary complex with calcium and thymidine 3{prime},5{prime}-bisphosphate at pH 5.1 (H{sub 2}O) or pH* 5.5 ({sup 2}H{sub 2}O). Samples of recombinant nuclease were labeled with {sup 13}C or {sup 15}N as appropriate to individual NMR experiments: uniformly with {sup 15}N (all sites to >95%), uniformly with {sup 13}C (all sites to 26%), selectively with {sup 13}C (single amino acids uniformly labeled to >26%), or selectively with {sup 15}N (single amino acids uniformly labeled to >95%). NMR data used in the analysis included single-bond and multiple-bond {sup 1}H-{sup 13}C and multiple-bond {sup 1}H-{sup 15}N correlations, {sup 1}H-{sup 13}C single-bond correlations with Hartmann-Hahn relay ({sup 1}H({sup 13}C)SBC-HH), and {sup 1}H-{sup 13}C single-bond correlation with NOE relay ({sup 1}H({sup 13}C)SBC-NOE). The aromatic protons of the spin systems were identified from {sup 1}H({sup 13}C)SBC-HH data, and the nonprotonated aromatic ring carbons were identified from {sup 1}H-{sup 13}C multiple-bond correlations. Measurement of NOE buildup rates between protons on different aromatic residues of the major ternary complex species yielded a number of interproton distances that could be compared with those from X-ray structures of the wild-type nuclease ternary complex with calcium and thymidine 3{prime},5{prime}-bisphosphate.

  19. Muon spin relaxation and hyperfine-enhanced Pr141 nuclear spin dynamics in Pr(Os,Ru)4Sb12 and (Pr,La)Os4Sb12

    NASA Astrophysics Data System (ADS)

    Shu, Lei; Maclaughlin, D. E.; Aoki, Y.; Tunashima, Y.; Yonezawa, Y.; Sanada, S.; Kikuchi, D.; Sato, H.; Heffner, R. H.; Higemoto, W.; Ohishi, K.; Ito, T. U.; Bernal, O. O.; Hillier, A. D.; Kadono, R.; Koda, A.; Ishida, K.; Sugawara, H.; Frederick, N. A.; Yuhasz, W. M.; Sayles, T. A.; Yanagisawa, T.; Maple, M. B.

    2007-07-01

    Zero- and longitudinal-field muon spin relaxation experiments have been carried out in the alloy series Pr(Os1-xRux)4Sb12 and Pr1-yLayOs4Sb12 to elucidate the anomalous dynamic muon spin relaxation observed in these materials. The damping rate ? associated with this relaxation varies with temperature, applied magnetic field, and dopant concentrations x and y in a manner consistent with the hyperfine enhancement of Pr141 nuclear spins first discussed by Bleaney [Physica (Utrecht) 69, 317 (1973)]. This mechanism arises from Van Vleck-like admixture of magnetic Pr3+ crystalline-electric-field-split excited states into the nonmagnetic singlet ground state by the nuclear hyperfine coupling, thereby increasing the strengths of spin-spin interactions between Pr141 and muon spins and within the Pr141 spin system. We find qualitative agreement with this scenario and conclude that electronic spin fluctuations are not directly involved in the dynamic muon spin relaxation.

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

    SciTech Connect

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

    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.

  1. Spin polarized asymmetric nuclear matter and neutron star matter within the lowest order constrained variational method

    SciTech Connect

    Bordbar, G. H.; Bigdeli, M.

    2008-01-15

    In this paper, we calculate properties of the spin polarized asymmetrical nuclear matter and neutron star matter, using the lowest order constrained variational (LOCV) method with the AV{sub 18}, Reid93, UV{sub 14}, and AV{sub 14} potentials. According to our results, the spontaneous phase transition to a ferromagnetic state in the asymmetrical nuclear matter as well as neutron star matter do not occur.

  2. Splitting of the one-body potential in spin-polarized isospin-symmetric nuclear matter

    SciTech Connect

    Sammarruca, Francesca

    2010-08-15

    Spin-polarized symmetric nuclear matter is studied within the Dirac-Brueckner-Hartree-Fock approach. We pay particular attention to the difference between the one-body potentials of upward and downward polarized nucleons. This is formally analogous to the Lane potential for isospin-asymmetric nuclear matter. We point out the necessity for additional information on this fundamentally important quantity and suggest ways to constrain it.

  3. On nuclear spin statistics in rotational transition intensities in tetrahedral AB4 molecules

    NASA Technical Reports Server (NTRS)

    Rosenberg, A.; Susskind, J.

    1979-01-01

    A general expression is derived for the integrated intensity of rotational transitions in the vibronic ground state of tetrahedral molecules, taking into account the nuclear spin statistics. It is shown that the ratio of this expression to previously published spin-free integrated intensities depends only on the tensor character N of the operator driving the transition, the appropriate rotational quantum numbers J and J', and the nuclear spin of the identical nuclei. Tables are given for N = 3, 4 and J no more than 50, which enable the calculation of integrated intensities for octopole and hexadecapole collision-induced dipole-moment transitions, centrifugal-distortion-induced dipole-moment transitions, and centrifugal-distortion-induced anisotropic-polarizability-tensor Raman transitions.

  4. Coherent Population Trapping of a Single Nuclear Spin Under Ambient Conditions

    NASA Astrophysics Data System (ADS)

    Jamonneau, P.; Hétet, G.; Dréau, A.; Roch, J.-F.; Jacques, V.

    2016-01-01

    We demonstrate coherent population trapping of a single nuclear spin in a room-temperature solid. To this end, we exploit a three-level system with a Λ configuration in the microwave domain, which consists of nuclear spin states addressed through their hyperfine coupling to the electron spin of a single nitrogen-vacancy defect in diamond. Moreover, the Λ -scheme relaxation is externally controlled through incoherent optical pumping and separated in time from consecutive coherent microwave excitations. Such a scheme allows us (i) to monitor the sequential accumulation of population into the dark state and (ii) to reach a novel regime of coherent population trapping dynamics for which periodic arrays of dark resonances can be observed, owing to multiple constructive interferences. This Letter offers new prospects for quantum state preparation, information storage in hybrid quantum systems, and metrology.

  5. Coherent Population Trapping of a Single Nuclear Spin Under Ambient Conditions.

    PubMed

    Jamonneau, P; Htet, G; Drau, A; Roch, J-F; Jacques, V

    2016-01-29

    We demonstrate coherent population trapping of a single nuclear spin in a room-temperature solid. To this end, we exploit a three-level system with a ? configuration in the microwave domain, which consists of nuclear spin states addressed through their hyperfine coupling to the electron spin of a single nitrogen-vacancy defect in diamond. Moreover, the ?-scheme relaxation is externally controlled through incoherent optical pumping and separated in time from consecutive coherent microwave excitations. Such a scheme allows us (i)to monitor the sequential accumulation of population into the dark state and (ii)to reach a novel regime of coherent population trapping dynamics for which periodic arrays of dark resonances can be observed, owing to multiple constructive interferences. This Letter offers new prospects for quantum state preparation, information storage in hybrid quantum systems, and metrology. PMID:26871331

  6. Deterministic preparation of Dicke states of donor nuclear spins in silicon by cooperative pumping

    NASA Astrophysics Data System (ADS)

    Luo, Yu; Yu, Hongyi; Yao, Wang

    2012-04-01

    For donor nuclear spins in silicon, we show how to deterministically prepare various symmetric and asymmetric Dicke states which span a complete basis of the many-body Hilbert space. The state preparation is realized by cooperative pumping of nuclear spins by coupled donor electrons, and the required controls are in situ to the prototype Kane proposal for quantum computation. This scheme only requires a subgigahertz donor exchange coupling, which can be readily achieved without atomically precise donor placement, and hence it offers a practical way to prepare multipartite entanglement of spins in silicon with current technology. All desired Dicke states appear as the steady state under various pumping scenarios, and therefore the preparation is robust and does not require accurate temporal controls. Numerical simulations with realistic parameters show that Dicke states of 10-20 qubits can be prepared with high fidelity in the presence of decoherence and unwanted dynamics.

  7. Electric readout and storage concepts for electron and nuclear spin states in silicon

    NASA Astrophysics Data System (ADS)

    Boehme, Christoph

    2011-10-01

    A variety of concepts utilizing spins in semiconductors for information storage and processing have been proposed in recent years. One of these concepts [1] uses the phosphorous nucleus in crystalline silicon as a quantum bit, an approach which combines longest known spin coherence times and, therefore, spin storage times, with already existing, well developed and highly reliable, crystalline silicon nano-technology. Our research is focused on implementations of electric readout devices for electron- and nuclear-spins in silicon. I will review different experiments which show how donor electrons [2-4] and nuclear [5] spins of phosphorous atoms in crystalline silicon can be used as a electrically readable spin memories with long storage times for classical and quantum information and how nuclear spin qubits can be initialized [6].[4pt] [1] B. E. Kane, Nature 393, 133 (1998).[0pt] [2] A. R. Stegner, C. Boehme, H. Huebl, M. Stutzmann, K. Lips, M. S. Brandt, Nature Physics 2, 835 (2006). [0pt] [3] S.-Y. Paik, S.-Y. Lee, W. J. Baker, D. R. McCamey, and C. Boehme, Phys. Rev. B 81, 075214 (2010).[0pt] [4] G. W. Morley, D. R. McCamey, H. A. Seipel, L.-C. Brunel, J. van Tol, C. Boehme, Phys. Rev. Lett. 101, 207602 (2008).[0pt] [5] D. R. McCamey, J. van Tol, G. W. Morley, C. Boehme, Science 330, 1652 (2010).[0pt] [6] D. R. McCamey, J. van Tol, G. W. Morley, C. Boehme, Phys. Rev. Lett. 102, 027601 (2009).

  8. 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 chains spin relaxation rates is attributed to cationcation 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 spinlattice relaxation time (T{sub 1}) measurements to calculate rotational correlation times for CH 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.

  9. Spin dynamics under the Hamiltonian varying with time in discrete steps: Molecular dynamics-based simulation of electron and nuclear spin relaxation in aqueous nickel(II)

    NASA Astrophysics Data System (ADS)

    Odelius, Michael; Ribbing, Carl; Kowalewski, Jozef

    1996-03-01

    A method of calculating the time correlation functions for electron spin is proposed, based on solving the time-dependent Schrdinger equation for a spin Hamiltonian that contains a term varying randomly in discrete time steps. It is applied to the study of electron spin relaxation in aqueous solution of nickel(II) ions with S=1. The random term in the spin Hamiltonian in this case is the zero-field splitting (ZFS) interaction. The method is evaluated by an application to a model system (the pseudorotation model) for which an analytical solution to the electron spin relaxation problem is known. The same method is then employed to study the electron and nuclear spin dynamics in a system where the time variation of the zero-field splitting is obtained by a combination of ab initio quantum chemistry and molecular dynamics simulations.

  10. Nuclear Spin Dependent Chemistry of the Trihydrogen Cation in Diffuse Interstellar Clouds

    NASA Astrophysics Data System (ADS)

    Crabtree, Kyle

    2015-05-01

    The trihydrogen cation, H3+,long thought to be the species responsible for initiating ion-molecule chemistry in the interstellar medium, was first observed in interstellar clouds twenty years ago. Since its detection, this cation has been used to infer temperatures, densities, cloud sizes, and the local cosmic ray ionization rate. However, in diffuse molecular clouds the excitation temperature of its two nuclear spin modifications, ortho (I = 3 / 2) and para-H3+(I = 1 / 2) is found to differ markedly from the cloud kinetic temperature inferred from the spin modifications of molecular hydrogen (H2) in the same environment. A steady state analysis of the chemical kinetics of ortho and para-H3+suggests that the interplay of thermalizing collisions with H2 and nuclear spin dependent dissociative recombination with electrons may result in a nonthermal excitation temperature. Each of these processes is complex. Collisions between H3+and H2 must obey selection rules based on conservation of nuclear spin angular momentum, and the allowed spin conversion reactions, which proceed through the fluxional (H5+)* intermediate, each have different statistical weights and energetic requirements. Meanwhile, theoretical and experimental studies of H3+electron recombination carried out over the past 40 years have yielded rates that span 4 orders of magnitude in range. We will present experimental measurements of the nuclear spin dependence of the reactions of H3+with H2 and with electrons, as well as astronomical observations of H3+in diffuse molecular clouds and time-dependent chemical modeling of these environments. Astrochemical models incorporating the latest experimental data still do not satisfactorily explain the observed excitation temperature in diffuse molecular clouds, and point to the need for state-selective measurements of the H3+electron recombination rate.

  11. Irreversible adiabatic decoherence of dipole-interacting nuclear-spin pairs coupled with a phonon bath

    NASA Astrophysics Data System (ADS)

    Domínguez, F. D.; González, C. E.; Segnorile, H. H.; Zamar, R. C.

    2016-02-01

    We study the quantum adiabatic decoherence of a multispin array, coupled with an environment of harmonic phonons, in the framework of the theory of open quantum systems. We follow the basic formal guidelines of the well-known spin-boson model, since in this framework it is possible to derive the time dependence of the reduced density matrix in the adiabatic time scale, without resorting to coarse-graining procedures. However, instead of considering a set of uncoupled spins interacting individually with the boson field, the observed system in our model is a network of weakly interacting spin pairs; the bath corresponds to lattice phonons, and the system-environment interaction is generated by the variation of the dipole-dipole energy due to correlated shifts of the spin positions, produced by the phonons. We discuss the conditions that the model must meet in order to fit within the adiabatic regime. By identifying the coupling of the dipole-dipole spin interaction with the low-frequency acoustic modes as the source of decoherence, we calculate the decoherence function of the reduced spin density matrix in closed way, and estimate the decoherence rate of a typical element of the reduced density matrix in one- and three-dimensional models of the spin array. Using realistic values for the various parameters of the model we conclude that the dipole-phonon mechanism can be particularly efficient to degrade multispin coherences, when the number of active spins involved in a given coherence is high. The model provides insight into the microscopic irreversible spin dynamics involved in the buildup of quasiequilibrium states and in the coherence leakage during refocusing experiments in nuclear magnetic resonance of crystalline solids.

  12. Two-dimensional NMR studies of staphylococcal nuclease: evidence for conformational heterogeneity from hydrogen-1, carbon-13, and nitrogen-15 spin system assignments of the aromatic amino acids in the nuclease H124L-thymidine 3',5'-bisphosphate-Ca2+ ternary complex.

    PubMed

    Wang, J F; Hinck, A P; Loh, S N; Markley, J L

    1990-05-01

    A combination of multinuclear two-dimensional NMR experiments served to identify and assign the combined 1H, 13C, and 15N spin systems of the single tryptophan, three phenylalanines, three histidines, and seven tyrosines of staphylococcal nuclease H124L in its ternary complex with calcium and thymidine 3',5'-bisphosphate at pH 5.1 (H2O) or pH 5.5 (2H2O). Samples of recombinant nuclease were labeled with 13C or 15N as appropriate to individual NMR experiments: uniformly with 15N (all sites to greater than 95%), uniformly with 13C (all sites to 26%), selectively with 13C (single amino acids uniformly labeled to 26%), or selectively with 15N (single amino acids uniformly labeled to greater than 95%). NMR data used in the analysis included single-bond and multiple-bond 1H-13C and multiple-bond 1H-15N correlations, 1H-13C single-bond correlation with Hartmann-Hahn relay (1H[13C]SBC-HH), and 1H-13C single-bond correlation with NOE relay (1H[13C]SBC-NOE). The aromatic protons of the spin systems were identified from 1H[13C]SBC-HH data, and the nonprotonated aromatic ring carbons were identified from 1H-13C multiple-bond correlations. Sequence-specific assignments were made on the basis of observed NOE relay connectivities between assigned 1H alpha-13C alpha or 1H beta-13C beta direct cross peaks in the aliphatic region [Wang, J., LeMaster, D. M., & Markley, J. L. (1990) Biochemistry 29, 88-101] and 1H delta-13C delta direct cross peaks in the aromatic region of the 1H[13C]SBC-NOE spectrum. The His121 1H delta 2 resonance, which has an unusual upfield shift (at 4.3 ppm in the aliphatic region), was assigned from 1H[13C]SBC, 1H[13C]MBC, and 1H[15N]MBC data. Evidence for local structural heterogeneity in the ternary complex was provided by doubled peaks assigned to His46, one tyrosine, and one phenylalanine. Measurement of NOE buildup rates between protons on different aromatic residues of the major ternary complex species yielded a number of interproton distances that could be compared with those from X-ray structures of the wild-type nuclease ternary complex with calcium and thymidine 3',5'-bisphosphate [Cotton, F. A., Hazen, E. E., Jr., & Legg, M. J. (1979) Proc. Natl. Acad. Sci. U.S.A. 76, 2551-2555; Loll, P. J., & Lattman, E. E. (1989) Proteins: Struct., Funct., Genet. 5, 183-201]. The unusual chemical shift of His121 1H delta 2 is consistent with ring current calculations from either X-ray structure. PMID:2361141

  13. Spin Noise Detection of Nuclear Hyperpolarization at 1.2 K

    PubMed Central

    Pöschko, Maria Theresia; Vuichoud, Basile; Milani, Jonas; Bornet, Aurélien; Bechmann, Matthias; Bodenhausen, Geoffrey; Jannin, Sami; Müller, Norbert

    2015-01-01

    We report proton spin noise spectra of a hyperpolarized solid sample of commonly used “DNP (dynamic nuclear polarization) juice” containing TEMPOL (4-hydroxy-2,2,6,6-tetramethylpiperidine N-oxide) and irradiated by a microwave field at a temperature of 1.2 K in a magnetic field of 6.7 T. The line shapes of the spin noise power spectra are sensitive to the variation of the microwave irradiation frequency and change from dip to bump, when the electron Larmor frequency is crossed, which is shown to be in good accordance with theory by simulations. Small but significant deviations from these predictions are observed, which can be related to spin noise and radiation damping phenomena that have been reported in thermally polarized systems. The non-linear dependence of the spin noise integral on nuclear polarization provides a means to monitor hyperpolarization semi-quantitatively without any perturbation of the spin system by radio frequency irradiation. PMID:26477605

  14. 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.

  15. Nuclear orientation of radon isotopes by spin-exchange optical pumping

    SciTech Connect

    Kitano, M.; Calaprice, F.P.; Pitt, M.L.; Clayhold, J.; Happer, W.; Kadar-Kallen, M.; Musolf, M.; Ulm, G.; Wendt, K.; Chupp, T.

    1988-05-23

    This paper reports the first demonstration of nuclear orientation of radon atoms. The method employed was spin exchange with potassium atoms polarized by optical pumping. The radon isotopes were produced at the ISOLDE isotope separator of CERN. The nuclear alignment of /sup 209/Rn and /sup 223/Rn has been measured by observation of ..gamma..-ray anisotropies and the magnetic dipole moment for /sup 209/Rn has been measured by the nuclear-magnetic-resonance method to be chemically bond..mu..chemically bond = 0.838 81(39)..mu../sub N/.

  16. Spin- and isospin-polarized states of nuclear matter in the Dirac-Brueckner-Hartree-Fock model

    SciTech Connect

    Sammarruca, Francesca

    2011-06-15

    Spin-polarized isospin asymmetric nuclear matter is studied within the Dirac-Brueckner-Hartree-Fock approach. After a brief review of the formalism, we present and discuss the self-consistent single-particle potentials at various levels of spin and isospin asymmetry. We then move to predictions of the energy per particle, also under different conditions of isospin and spin polarization. Comparison with the energy per particle in isospin symmetric or asymmetric unpolarized nuclear matter shows no evidence for a phase transition to a spin-ordered state, neither ferromagnetic nor antiferromagnetic.

  17. Employing Forbidden Transitions as Qubits in a Nuclear Spin-Free Chromium Complex.

    PubMed

    Fataftah, Majed S; Zadrozny, Joseph M; Coste, Scott C; Graham, Michael J; Rogers, Dylan M; Freedman, Danna E

    2016-02-01

    The implementation of quantum computation (QC) would revolutionize scientific fields ranging from encryption to quantum simulation. One intuitive candidate for the smallest unit of a quantum computer, a qubit, is electronic spin. A prominent proposal for QC relies on high-spin magnetic molecules, where multiple transitions between the many MS levels are employed as qubits. Yet, over a decade after the original notion, the exploitation of multiple transitions within a single manifold for QC remains unrealized in these high-spin species due to the challenge of accessing forbidden transitions. To create a proof-of-concept system, we synthesized the novel nuclear spin-free complex [Cr(C3S5)3](3-) with precisely tuned zero-field splitting parameters that create two spectroscopically addressable transitions, with one being a forbidden transition. Pulsed electron paramagnetic resonance (EPR) measurements enabled the investigation of the coherent lifetimes (T2) and quantum control (Rabi oscillations) for two transitions, one allowed and one forbidden, within the S = (3)/2 spin manifold. This investigation represents a step forward in the development of high-spin species as a pathway to scalable QC systems within magnetic molecules. PMID:26739626

  18. Disorder-enhanced nuclear spin relaxation at Landau level filling factor one

    NASA Astrophysics Data System (ADS)

    Guan, Tong; Benedikt, Friess; Li, Yong-Qing; Yan, Shi-Shen; Vladimir, Umansky; Klaus von, Klitzing; Jurgen, H. Smet

    2015-06-01

    The nuclear spin relaxation rate (1/T1) is measured for GaAs two-dimensional (2D) electron systems in the quantum Hall regime with an all-electrical technique for agitating and probing the nuclear spins. A tilted plateau feature is observed near the Landau level filling factor ? = 1 in 1/T1 versus ?. Both the width and magnitude of the plateau increase with decreasing electron density. At low temperatures, 1/T1 exhibits an Arrhenius temperature dependence within the tilted plateau regime. The extracted energy gaps are up to two orders of magnitude smaller than the corresponding charge transport gaps. These results point to a nontrivial mechanism for the disorder-enhanced nuclear spin relaxation, in which microscopic inhomogeneities play a key role for the low energy spin excitations related to skyrmions. Project supported by the National Basic Research Program of China (Grant Nos. 2012CB921703 and 2015CB921102), the National Natural Science Foundation of China (Grant Nos. 91121003, 11374337, and 61425015), the Chinese Academy of Sciences, the BMBF, and the German-Israel Foundation.

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

    NASA Astrophysics Data System (ADS)

    Ajoy, Ashok; Bissbort, Ulf; Liu, Yixiang; Marseglia, Luca; Saha, Kasturi; Cappellaro, Paola

    2015-05-01

    Recent developments in materials fabrication and coherent control have brought quantum magnetometers based on electronic spin defects in diamond close to single nuclear spin sensitivity. These quantum sensors have the potential to be a revolutionary tool in proteomics, thus helping drug discovery: They can overcome some of the challenges plaguing other experimental techniques (x-ray and NMR) and allow single protein reconstruction in their natural conditions. While the sensitivity of diamond-based magnetometers approaches the single nuclear spin level, the outstanding challenge is to resolve contributions arising from distinct nuclear spins in a dense sample and use the acquired signal to reconstruct their positions. This talk describes a strategy to boost the spatial resolution of NV-based magnetic resonance imaging, by combining the use of a quantum memory intrinsic to the NV system with Hamiltonian engineering by coherent quantum control. The proposed strategy promises to make diamond-based quantum sensors an invaluable technology for bioimaging, as they could achieve the reconstruction of biomolecules local structure without the need to crystallize them, to synthesize large ensembles or to alter their natural environment.

  20. Nanoscale nuclear magnetic resonance with a nitrogen-vacancy spin sensor.

    PubMed

    Mamin, H J; Kim, M; Sherwood, M H; Rettner, C T; Ohno, K; Awschalom, D D; Rugar, D

    2013-02-01

    Extension of nuclear magnetic resonance (NMR) to nanoscale samples has been a longstanding challenge because of the insensitivity of conventional detection methods. We demonstrated the use of an individual, near-surface nitrogen-vacancy (NV) center in diamond as a sensor to detect proton NMR in an organic sample located external to the diamond. Using a combination of electron spin echoes and proton spin manipulation, we showed that the NV center senses the nanotesla field fluctuations from the protons, enabling both time-domain and spectroscopic NMR measurements on the nanometer scale. PMID:23372008

  1. Nuclear Spin Ordering on the Surface of a He3 Crystal: Magnetic Steps

    NASA Astrophysics Data System (ADS)

    Todoshchenko, I. A.; Alles, H.; Junes, H. J.; Manninen, M. S.; Parshin, A. Ya.

    2009-06-01

    The growth rates of the (110) and (100) facets on bcc He3 crystals have been measured near the magnetic ordering transition at TN=0.93mK. In the ordered phase, we have observed several growth modes which correspond to different values of the step energy. We show that, because of quantum delocalization, the step induces a cluster of ferromagnetically ordered nuclear spins. The free energy of such a cluster is relatively large and depends on the orientation of the underlying antiferromagnetic domain. In the paramagnetic phase, the mobilities of the basic facets are greatly reduced because of the much slower spin diffusion in the bulk solid.

  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. Magnetic equivalence of terminal nuclei in the azide anion broken by nuclear spin relaxation

    NASA Astrophysics Data System (ADS)

    Bernatowicz, P.; Szyma?ski, S.

    NMR spectra of water solution of sodium azide selectively 15N labelled in the central position were studied using an iterative least-squares method. In agreement with predictions based on Bloch-Wangsness-Redfield nuclear spin relaxation theory, it is demonstrated that quadrupolar relaxation of the magnetically equivalent terminal 14N (spin-1) nuclei in the azide anion renders the J coupling between these nuclei an observable quantity. In isotropic fluids, this seems to be the first experimental evidence of relaxation-broken magnetic equivalence symmetry.

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

    NASA Astrophysics Data System (ADS)

    Khoo, T. L.; Chowdhury, P.; Ahmad, I.; Borggreen, J.; Emling, H.; Frekers, D.; Janssens, R. V. F.; Pakkanen, A.; Chung, Y. H.; Day, P. J.

    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 Dy 154 sub 88. The role of rotation aligned configurations in the shape change is discussed.

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

    SciTech Connect

    Gerlovin, I. Ya.; Cherbunin, R. V.; Ignatiev, I. V.; Kuznetsova, M. S.; Verbin, S. Yu.; Flisinski, K.; Bayer, M.; Reuter, D.; Wieck, A. D.; Yakovlev, D. R.

    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.

  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. High-pressure Magic Angle Spinning Nuclear Magnetic Resonance

    SciTech Connect

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

    2011-10-01

    A high-pressure magic angle spinning (MAS) NMR capability, consisting of a reusable high-pressure MAS rotor, a high-pressure 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 to include micro-groves at 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 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 penetration loss of pressure for 72 hours. As an application example, in situ 13C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg2SiO4) reacted with supercritical CO2 and H2O at 150 bar and 50C are reported, with relevance to geological sequestration of carbon dioxide.

  8. QUANTUM SIMULATION. Localization-delocalization transition in the dynamics of dipolar-coupled nuclear spins.

    PubMed

    Álvarez, Gonzalo A; Suter, Dieter; Kaiser, Robin

    2015-08-21

    Nonequilibrium dynamics of many-body systems are important in many scientific fields. Here, we report the experimental observation of a phase transition of the quantum coherent dynamics of a three-dimensional many-spin system with dipolar interactions. Using nuclear magnetic resonance (NMR) on a solid-state system of spins at room-temperature, we quench the interaction Hamiltonian to drive the evolution of the system. Depending on the quench strength, we then observe either localized or extended dynamics of the system coherence. We extract the critical exponents for the localized cluster size of correlated spins and diffusion coefficient around the phase transition separating the localized from the delocalized dynamical regime. These results show that NMR techniques are well suited to studying the nonequilibrium dynamics of complex many-body systems. PMID:26293957

  9. Spin distribution of nuclear levels using the static path approximation with the random-phase approximation

    SciTech Connect

    Kaneko, K.; Schiller, A.

    2007-04-15

    We present a thermal and quantum-mechanical treatment of nuclear rotation using the formalism of the static path approximation plus the random-phase approximation. Naive perturbation theory fails because of the presence of zero-frequency modes resulting from dynamical symmetry breaking. Such modes lead to infrared divergences. We show that composite zero-frequency excitations are properly treated within the collective coordinate method. The resulting perturbation theory is free from infrared divergences. Without the assumption of individual random spin vectors, we derive microscopically the spin distribution of the level density. The moment of inertia is thereby related to the spin-cutoff parameter in the usual way. Explicit calculations are performed for {sup 56}Fe; various thermal properties are discussed. In particular, we demonstrate that the increase of the moment of inertia with increasing temperature is correlated with the suppression of pairing correlations.

  10. 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 Jπ=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.

  11. Probing the effective nuclear-spin magnetic field in a single quantum dot via full counting statistics

    SciTech Connect

    Xue, Hai-Bin; Nie, Yi-Hang; Chen, Jingzhe; Ren, Wei

    2015-03-15

    We study theoretically the full counting statistics of electron transport through a quantum dot weakly coupled to two ferromagnetic leads, in which an effective nuclear-spin magnetic field originating from the configuration of nuclear spins is considered. We demonstrate that the quantum coherence between the two singly-occupied eigenstates and the spin polarization of two ferromagnetic leads play an important role in the formation of super-Poissonian noise. In particular, the orientation and magnitude of the effective field have a significant influence on the variations of the values of high-order cumulants, and the variations of the skewness and kurtosis values are more sensitive to the orientation and magnitude of the effective field than the shot noise. Thus, the high-order cumulants of transport current can be used to qualitatively extract information on the orientation and magnitude of the effective nuclear-spin magnetic field in a single quantum dot. - Highlights: • The effective nuclear-spin magnetic field gives rise to the off-diagonal elements of the reduced density matrix of single QD. • The off-diagonal elements of reduced density matrix of the QD have a significant impact on the high-order current cumulants. • The high-order current cumulants are sensitive to the orientation and magnitude of the effective nuclear-spin magnetic field. • The FCS can be used to detect the orientation and magnitude of the effective nuclear-spin magnetic field in a single QD.

  12. All electrical probe of nuclear spin polarization and relaxation by spin phase transition peaks of the filling fraction ? = 2/3 quantum hall effect

    NASA Astrophysics Data System (ADS)

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

    2012-05-01

    We developed a sensitive spectroscopic tool to probe resistively as low as a few percent of an ensemble of nuclear spin polarizations in a GaAs quantum well. We take advantage of the spinphase-transition (SPT) peak of the filling fraction ? = 2/3 quantum Hall effect at which the electronic systems are energetically degenerate. The non-zero nuclear spin polarization incorporated in the system would be perceived as an effective magnetic field B N that modifies the Zeeman energy exclusively. It would result in a change in the overall shape of the peak including the peak's position, width, and amplitude. The alteration of the shape of the overall peak provide essential information on the microscopic characteristics of nuclear spin polarization and its relation to the domain formations which was not well investigated in the previous reports.

  13. A nuclear spin-based 129Xe and 131Xe using optical polarization

    NASA Astrophysics Data System (ADS)

    Zhou, Binquan; Chen, Linlin; Lei, Guanqun; Quan, Wei; Meng, Xiaofeng; Fang, Jiancheng

    2015-10-01

    We present a design for a spin-exchange optical pumping system to produce large quantities of highly polarized 129Xe and 131Xe. Low xenon concentrations in the flowing gas mixture which allow the laser to maintain high Cs polarization. The large spin-exchange rate between Cs and Xe through the long-lived van der Waals molecules at low pressure, combined with a high flow rate, results in large production rates of hyperpolarized xenon. The fast rates make it possible to obtain large nuclear polarizations after several minutes of optical pumping with a laser.At high Xe pressures. According to the theory, the longitudinal spin-elaxation rate 1T1 of Xe in a high-pressure sample containing only Xe and Cs vapor has the simple form is the velocity averaged binary spin-exchange cross section, It is the relaxation rate due to wall collisions and perhaps magnetic field inhomogeneities. Our results complement earlier studies performed at 129Xe pressures of about 20 Torr and 131Xe pressures of about 20 Torr and N2 pressures of 600 Torr . This work is useful for predicting spin-exchange rates between polarized Cs atoms and Xe nuclei.

  14. Diamond as a Solid State Quantum Computer with a Linear Chain of Nuclear Spins System

    NASA Astrophysics Data System (ADS)

    Lpez, G. V.; Lpez, G. V.

    By removing a $^{12}C$ atom from the tetrahedral configuration of the diamond, replace it by a $^{13}C$ atom, and repeating this in a linear direction, it is possible to have a linear chain of nuclear spins one half and to build a solid state quantum computer. One qubit rotation and controlled-not (CNOT) quantum gates are obtained immediately from this configuration, and CNOT quantum gate is used to determined the design parameters of this quantum computer.

  15. Nuclear-spin relaxation of ?Pb in ferroelectric powders

    SciTech Connect

    Bouchard, Louis S.; Sushkov, Alexander O.; Budker, Dmitry; Ford, Joe; Lipton, Andrew S.

    2008-02-05

    The ?Pb nuclear system (nuclear spin I = 1/2; magnetic Moment ? ?0.58 ?N; isotopic abundance ? 22%) in ferroelectric solids has been proposed for a search for a Schiff moment associated with simultaneous violation of parity (P) and time-reversal invariance (T) in fundamental interactions [1] (see also a discussion of the sensitivity of such search in Ref. [2]). The idea is that, due to the Schiff moment, a ferroelectric sample would acquire a P,T-odd magnetic polarization along the direction of its electric polarization. In conclusion, we have presented the first experimental study of relaxation properties of ?Pb in PT and PZT below room temperature. We find that above T? 50 K, longitudinal relaxation rate follows the T dependence characteristic of the two-phonon Raman process. On the other hand, as the temperature is decreased below T? 50 K, the longitudinal relaxation rates drop slower than ?T2 (as opposed to ?T7 expected for the Raman process), and the relaxation is probably due to a direct process associated with paramagnetic impurities and nuclear-spin diffusion. While the longitudinal relaxation times T? vary between several seconds and over an hour in the temperature range between 290 and 10 K, the transverse relaxation time T? is found to be ?1.5 ms for all temperatures and all powder samples studied. D: we never discuss the origin of T? relaxation. Maybe we should. 1.5 ms is only a bit shorter from what would be expected from nuclear spin-spin interactions. Any comments? At some point Sasha asked Oleg to calculate T? exactly for PT and PZT, but I forgot what was the result. If such calculation exists, it would be great to compare with the expt. result. The obtained results provide an important input in the design of the experiments to search for P,T-violating effects in solid ferroelectrics

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

    SciTech Connect

    Obaid, Rana; Kinzel, Daniel; Oppel, Markus González, Leticia

    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.

  17. Quantum cognition: The possibility of processing with nuclear spins in the brain

    NASA Astrophysics Data System (ADS)

    Fisher, Matthew P. A.

    2015-11-01

    The possibility that quantum processing with nuclear spins might be operative in the brain is explored. Phosphorus is identified as the unique biological element with a nuclear spin that can serve as a qubit for such putative quantum processing-a neural qubit-while the phosphate ion is the only possible qubit-transporter. We identify the "Posner molecule", Ca9(PO4)6, as the unique molecule that can protect the neural qubits on very long times and thereby serve as a (working) quantum-memory. A central requirement for quantum-processing is quantum entanglement. It is argued that the enzyme catalyzed chemical reaction which breaks a pyrophosphate ion into two phosphate ions can quantum entangle pairs of qubits. Posner molecules, formed by binding such phosphate pairs with extracellular calcium ions, will inherit the nuclear spin entanglement. A mechanism for transporting Posner molecules into presynaptic neurons during vesicle endocytosis is proposed. Quantum measurements can occur when a pair of Posner molecules chemically bind and subsequently melt, releasing a shower of intra-cellular calcium ions that can trigger further neurotransmitter release and enhance the probability of post-synaptic neuron firing. Multiple entangled Posner molecules, triggering non-local quantum correlations of neuron firing rates, would provide the key mechanism for neural quantum processing. Implications, both in vitro and in vivo, are briefly mentioned.

  18. {sigma}-nuclear spin-orbit coupling from two-pion exchange

    SciTech Connect

    Kaiser, N.

    2007-12-15

    Using SU(3) chiral perturbation theory we calculate the density-dependent complex-valued spin-orbit coupling strength U{sub {sigma}}{sub ls}(k{sub f})+iW{sub {sigma}}{sub ls}(k{sub f}) of a {sigma} hyperon in the nuclear medium. The leading long-range {sigma}N interaction arises from iterated one-pion exchange with a {lambda} or a {sigma} hyperon in the intermediate state. We find from this unique long-range dynamics a sizable ''wrong-sign'' spin-orbit coupling strength of U{sub {sigma}}{sub ls}(k{sub f0}){approx_equal}-20 MeV fm{sup 2} at normal nuclear matter density {rho}{sub 0}=0.16 fm{sup -3}. The strong {sigma}N{yields}{lambda}N conversion process contributes at the same time an imaginary part of W{sub {sigma}}{sub ls}(k{sub f0}){approx_equal}-12 MeV fm{sup 2}. When combined with estimates of the short-range contribution the total {sigma}-nuclear spin-orbit coupling becomes rather weak.

  19. 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.

  20. A NEW METHOD FOR EXTRACTING SPIN-DEPENDENT NEUTRON STRUCTURE FUNCTIONS FROM NUCLEAR DATA

    SciTech Connect

    Kahn, Y.F.; Melnitchouk, W.

    2009-01-01

    High-energy electrons are currently the best probes of the internal structure of nucleons (protons and neutrons). By collecting data on electrons scattering off light nuclei, such as deuterium and helium, one can extract structure functions (SFs), which encode information about the quarks that make up the nucleon. Spin-dependent SFs, which depend on the relative polarization of the electron beam and the target nucleus, encode quark spins. Proton SFs can be measured directly from electron-proton scattering, but those of the neutron must be extracted from proton data and deuterium or helium-3 data because free neutron targets do not exist. At present, there is no reliable method for accurately determining spin-dependent neutron SFs in the low-momentum-transfer regime, where nucleon resonances are prominent and the functions are not smooth. The focus of this study was to develop a new method for extracting spin-dependent neutron SFs from nuclear data. An approximate convolution formula for nuclear SFs reduces the problem to an integral equation, for which a recursive solution method was designed. The method was then applied to recent data from proton and deuterium scattering experiments to perform a preliminary extraction of spin-dependent neutron SFs in the resonance region. The extraction method was found to reliably converge for arbitrary test functions, and the validity of the extraction from data was verifi ed using a Bjorken integral, which relates integrals of SFs to a known quantity. This new information on neutron structure could be used to assess quark-hadron duality for the neutron, which requires detailed knowledge of SFs in all kinematic regimes.

  1. Rotor Design for High Pressure Magic Angle Spinning Nuclear Magnetic Resonance

    SciTech Connect

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

    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 deg 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.

  2. Analytic treatment of nuclear spin-lattice relaxation for diffusion in a cone model

    NASA Astrophysics Data System (ADS)

    Sitnitsky, A. E.

    2011-12-01

    We consider nuclear spin-lattice relaxation rate resulted from a diffusion equation for rotational wobbling in a cone. We show that the widespread point of view that there are no analytical expressions for correlation functions for wobbling in a cone model is invalid and prove that nuclear spin-lattice relaxation in this model is exactly tractable and amenable to full analytical description. 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 cases 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 free isotropic rotational diffusion. The dependence of the spin-lattice relaxation rate on the cone half-width yields results similar to those predicted by the model-free approach.

  3. Spin-orbit effects on nuclear state preparation at the S -T+ anti-crossing in double quantum dots

    NASA Astrophysics Data System (ADS)

    Rancic, Marko; Burkard, Guido

    2014-03-01

    We explore the interplay of spin-orbit and hyperfine effects on the nuclear preparation schemes in two-electron double quantum dots, e.g. in GaAs. The quantity of utmost interest is the electron spin decoherence time T2* in dependence of the number of sweeps through the electron spin singlet S triplet T+ anti-crossing. Decoherence of the electron spin is caused by the difference field induced by the nuclear spins. We study the case where a singlet S(2 , 0) is initialized, in which both electrons are in the left dot. Subsequently, the system is driven repeatedly through the anti-crossing and back using linear electrical bias sweeps. Our model describes the passage through the anti-crossing with a large number of equally spaced, step-like parameter increments. We develop a numerical method describing the nuclear spins fully quantum mechanically, which allows us to track their dynamics. Both Rashba and Dresselhaus spin-orbit terms do depend on the angle ? between the [ 110 ] crystallographic and the inter-dot axis. Our results show that the suppression of decoherence (and therefore the enhancement of T2*) is inversely proportional to the strength of the spin-orbit interaction, which is tuned by varying the angle ?. We acknowledge the S3Nano Marie Curie ITN for support and funding.

  4. Nuclear Spin Polarization of Phosphorus Donors in Silicon. Direct Evidence from 31P-Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Gumann, Patryk; Ramanathan, Chandrasekhar; Patange, Om; Moussa, Osama; Thewalt, Mike; Riemann, Helge; Abrosimov, Nikolay; Becker, Peter; Pohl, Hans-Joachim; Itoh, Kohei; Cory, David G.

    2014-03-01

    We experimentally demonstrate the optical hyperpolarization and coherent control of 31P, nuclear spins in single crystal silicon via the inductive readout of the nuclear magnetic resonance (NMR) signal of 31P at a concentration of 1.5 x 1015 cc-1. The obtained polarization is sufficient the 31P spin polarization of 1.17 x 1015 in a 10 mm x 10 mm sample, observed in one FID with signal-to-noise ration of 113. The linewidth is 800 Hz. The Hahn echo pulse sequence reveals a 31P T2 time of 0.42 s at 1.6 K, which was extended by the Carr Purcell cycle to 1.2 s at the same temperature. The maximum build-up of the nuclear polarization was achieved within ~577 seconds, at 4.2 K, in 6.7 T, using optical excitations provided by an infra-red laser. This work has been supported by CERC Canada.

  5. Sensing of single nuclear spins in random thermal motion with proximate nitrogen-vacancy centers

    NASA Astrophysics Data System (ADS)

    Bruderer, M.; Fernández-Acebal, P.; Aurich, R.; Plenio, M. B.

    2016-03-01

    Nitrogen-vacancy (NV) centers in diamond have emerged as valuable tools for sensing and polarizing spins. Motivated by potential applications in chemistry, biology, and medicine, we show that NV-based sensors are capable of detecting single spin targets even if they undergo diffusive motion in an ambient thermal environment. Focusing on experimentally relevant diffusion regimes, we derive an effective model for the NV-target interaction, where parameters entering the model are obtained from numerical simulations of the target motion. The practicality of our approach is demonstrated by analyzing two realistic experimental scenarios: (i) time-resolved sensing of a fluorine nuclear spin bound to an N-heterocyclic carbene-ruthenium (NHC-Ru) catalyst that is immobilized on the diamond surface and (ii) detection of an electron spin label by an NV center in a nanodiamond, both attached to a vibrating chemokine receptor in thermal motion. We find in particular that the detachment of a fluorine target from the NHC-Ru carrier molecule can be monitored with a time resolution of a few seconds.

  6. Understanding electron and nuclear spin dynamics in Cr^5+ doped K3NbO8

    NASA Astrophysics Data System (ADS)

    Nellutla, Saritha

    2009-03-01

    Chromium(V) doped in the diamagnetic host potassium niobate, a simple spin S=.5ex1-.1em/ -.15em.25ex2 , I = 0 system, has been proposed as an alternative standard for field calibration and g-standard for high-field EPR [1]. This system constitutes a dilute two-level model relevant for use as a electron spin qubit [2] and as such coherent electron spin manipulation at X-band (9.5 GHz) was observed over a wide range temperature. Rabi oscillations are observed for the first time in a spin system based on transition metal oxides up to room temperature. At 4 K, a Rabi frequency ?R of 20 MHz together with the phase coherence relaxation (spin-spin relaxation) time, T2 of 10 ?s results in the single qubit figure of merit QM (=?RT2/?) as about 500, showing that a diluted ensemble of Cr(V) (S = 1/2) doped K3NbO8 is a potential candidate for solid-state quantum information processing. Also, the field and temperature dependence of the T1 (spin-lattice relaxation) and T2 times was investigated [3] for a further understanding of the relaxation mechanisms governing the phase decoherence in this system. These studies show that the coupling of the electron spin with the neighboring ^39K nuclei (I = 3/2) is one of the prominent T2 mechanisms. The hyperfine and quadrupole interactions with ^39K nuclei was resolved by using the high-frequency (240 GHz) pulsed electron nuclear double resonance (ENDOR). [3pt] [1]. B. Cage, A. Weekley, L. -C. Brunel and N. S. Dalal, Anal. Chem. 71, 1951 (1999). [0pt] [2]. S. Nellutla, K.-Y. Choi, M. Pati, J. van Tol, I. Chiroescu and N. S. Dalal, Phys. Rev. Lett. 99, 137601 (2007). [0pt] [3]. S. Nellutla, G. W. Morley, M. Pati, N. S. Dalal and J. van Tol, Phys. Rev. B. 78, 054426 (2008).

  7. Ignition conditions for inertial confinement fusion targets with a nuclear spin-polarized DT fuel

    NASA Astrophysics Data System (ADS)

    Temporal, M.; Brandon, V.; Canaud, B.; Didelez, J. P.; Fedosejevs, R.; Ramis, R.

    2012-10-01

    The nuclear fusion cross-section is modified when the spins of the interacting nuclei are polarized. In the case of deuterium-tritium it has been theoretically predicted that the nuclear fusion cross-section could be increased by a factor ? = 1.5 if all the nuclei were polarized. In inertial confinement fusion this would result in a modification of the required ignition conditions. Using numerical simulations it is found that the required hot-spot temperature and areal density can both be reduced by about 15% for a fully polarized nuclear fuel. Moreover, numerical simulations of a directly driven capsule show that the required laser power and energy to achieve a high gain scale as ?-0.6 and ?-0.4 respectively, while the maximum achievable energy gain scales as ?0.9.

  8. Nuclear spin ordering on the surface of a 3He crystal: magnetic steps.

    PubMed

    Todoshchenko, I A; Alles, H; Junes, H J; Manninen, M S; Parshin, A Ya

    2009-06-19

    The growth rates of the (110) and (100) facets on bcc (3)He crystals have been measured near the magnetic ordering transition at T_{N} = 0.93 mK. In the ordered phase, we have observed several growth modes which correspond to different values of the step energy. We show that, because of quantum delocalization, the step induces a cluster of ferromagnetically ordered nuclear spins. The free energy of such a cluster is relatively large and depends on the orientation of the underlying antiferromagnetic domain. In the paramagnetic phase, the mobilities of the basic facets are greatly reduced because of the much slower spin diffusion in the bulk solid. PMID:19659022

  9. 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

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

    PubMed Central

    McCain, D C

    1995-01-01

    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

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

    SciTech Connect

    Jimenez-Delgado, Pedro; Accardi, Alberto; Melnitchouk, Wally

    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.

  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. Finite-temperature calculations for spin-polarized asymmetric nuclear matter with the lowest order constrained variational method

    SciTech Connect

    Bigdeli, M.; Bordbar, G. H.; Poostforush, A.

    2010-09-15

    The lowest order constrained variational technique has been used to investigate some of the thermodynamic properties of spin-polarized hot asymmetric nuclear matter, such as the free energy, symmetry energy, susceptibility, and equation of state. We have shown that the symmetry energy of the nuclear matter is substantially sensitive to the value of spin polarization. Our calculations show that the equation of state of the polarized hot asymmetric nuclear matter is stiffer for higher values of the polarization as well as the isospin asymmetry parameter. Our results for the free energy and susceptibility show that spontaneous ferromagnetic phase transition cannot occur for hot asymmetric matter.

  14. Generalized nuclear Fukui functions in the framework of spin-polarized density-functional theory

    SciTech Connect

    Chamorro, E.; Proft, F. de; Geerlings, P.

    2005-08-22

    An extension of Cohen's nuclear Fukui function is presented in the spin-polarized framework of density-functional theory (SP-DFT). The resulting new nuclear Fukui function indices {phi}{sub N{alpha}} and {phi}{sub S{alpha}} are intended to be the natural descriptors for the responses of the nuclei to changes involving charge transfer at constant multiplicity and also the spin polarization at constant number of electrons. These generalized quantities allow us to gain new insights within a perturbative scheme based on DFT. Calculations of the electronic and nuclear SP-DFT quantities are presented within a Kohn-Sham framework of chemical reactivity for a sample of molecules, including H{sub 2}O, H{sub 2}CO, and some simple nitrenes (NX) and phosphinidenes (PX), with X=H, Li, F, Cl, OH, SH, NH{sub 2}, and PH{sub 2}. Results have been interpreted in terms of chemical bonding in the context of Berlin's theorem, which provides a separation of the molecular space into binding and antibinding regions.

  15. Resonance-inclined optical nuclear spin polarization of liquids in diamond structures

    NASA Astrophysics Data System (ADS)

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

    2016-02-01

    Dynamic nuclear polarization (DNP) of molecules in a solution at room temperature has the potential to revolutionize nuclear magnetic resonance spectroscopy and imaging. The prevalent methods for achieving DNP in solutions are typically most effective in the regime of small interaction correlation times between the electron and nuclear spins, limiting the size of accessible molecules. To solve this limitation, we design a mechanism for DNP in the liquid phase that is applicable for large interaction correlation times. Importantly, while this mechanism makes use of a resonance condition similar to solid-state DNP, the polarization transfer is robust to a relatively large detuning from the resonance due to molecular motion. We combine this scheme with optically polarized nitrogen-vacancy (NV) center spins in nanodiamonds to design a setup that employs optical pumping and is therefore not limited by room temperature electron thermal polarization. We illustrate numerically the effectiveness of the model in a flow cell containing nanodiamonds immobilized in a hydrogel, polarizing flowing water molecules 4700-fold above thermal polarization in a magnetic field of 0.35 T, in volumes detectable by current NMR scanners.

  16. Optical Measurement of the Effect of Electric Fields on the Nuclear Spin Coherence of Rare-Earth Ions in Solids

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    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 Eu151 in Y2SiO5 (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.

  17. Electron-mediated nuclear-spin interactions between distant nitrogen-vacancy centers.

    PubMed

    Bermudez, A; Jelezko, F; Plenio, M B; Retzker, A

    2011-10-01

    We propose a scheme enabling controlled quantum coherent interactions between separated nitrogen-vacancy centers in diamond in the presence of strong magnetic fluctuations. The proposed scheme couples nuclear qubits employing the magnetic dipole-dipole interaction between the electron spins and, crucially, benefits from the suppression of the effect of environmental magnetic field fluctuations thanks to a strong microwave driving. This scheme provides a basic building block for a full-scale quantum-information processor or quantum simulator based on solid-state technology. PMID:22107276

  18. Electron-Mediated Nuclear-Spin Interactions between Distant Nitrogen-Vacancy Centers

    NASA Astrophysics Data System (ADS)

    Bermudez, A.; Jelezko, F.; Plenio, M. B.; Retzker, A.

    2011-10-01

    We propose a scheme enabling controlled quantum coherent interactions between separated nitrogen-vacancy centers in diamond in the presence of strong magnetic fluctuations. The proposed scheme couples nuclear qubits employing the magnetic dipole-dipole interaction between the electron spins and, crucially, benefits from the suppression of the effect of environmental magnetic field fluctuations thanks to a strong microwave driving. This scheme provides a basic building block for a full-scale quantum-information processor or quantum simulator based on solid-state technology.

  19. Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR.

    PubMed

    Rosay, Melanie; Blank, Monica; Engelke, Frank

    2016-03-01

    Advances in dynamic nuclear polarization (DNP) instrumentation and methodology have been key factors in the recent growth of solid-state DNP NMR applications. We review the current state of the art of solid-state DNP NMR instrumentation primarily based on available commercial platforms. We start with a general system overview, including options for microwave sources and DNP NMR probes, and then focus on specific developments for DNP at 100K with magic angle spinning (MAS). Gyrotron microwave sources, passive components to transmit microwaves, the DNP MAS probe, a cooling device for low-temperature MAS, and sample preparation procedures including radicals for DNP are considered. PMID:26920834

  20. Instrumentation for solid-state dynamic nuclear polarization with magic angle spinning NMR

    NASA Astrophysics Data System (ADS)

    Rosay, Melanie; Blank, Monica; Engelke, Frank

    2016-03-01

    Advances in dynamic nuclear polarization (DNP) instrumentation and methodology have been key factors in the recent growth of solid-state DNP NMR applications. We review the current state of the art of solid-state DNP NMR instrumentation primarily based on available commercial platforms. We start with a general system overview, including options for microwave sources and DNP NMR probes, and then focus on specific developments for DNP at 100 K with magic angle spinning (MAS). Gyrotron microwave sources, passive components to transmit microwaves, the DNP MAS probe, a cooling device for low-temperature MAS, and sample preparation procedures including radicals for DNP are considered.

  1. 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.

    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.

  2. Proton-decoupled, Overhauser-enhanced, spatially localized carbon-13 spectroscopy in humans

    SciTech Connect

    Bottomley, P.A.; Hardy, C.J.; Roemer, P.B.; Mueller, O.M. )

    1989-12-01

    Spatially localized, natural abundance, carbon (13C) NMR spectroscopy has been combined with proton (1H) decoupling and nuclear Overhauser enhancement to improve 13C sensitivity up to five-fold in the human leg, liver, and heart. Broadhand-decoupled 13C spectra were acquired in 1 s to 17 min with a conventional 1.5-T imaging/spectroscopy system, an auxiliary 1H decoupler, an air-cooled dual-coil coplanar surface probe, and both depth-resolved surface coil spectroscopy (DRESS) and one-dimensional phase-encoding gradient NMR pulse sequences. The surface coil probe comprised circular and figure-eight-shaped coils to eliminate problems with mutual coupling of coils at high decoupling power levels applied during 13C reception. Peak decoupler RF power deposition in tissue was computed numerically from electromagnetic theory assuming a semi-infinite plane of uniform biological conductor. Peak values at the surface were calculated at 4 to 6 W/kg in any gram of tissue for each watt of decoupler power input excluding all coil and cable losses, warning of potential local RF heating problems in these and related experiments. The average power deposition was about 9 mW/kg per watt input, which should present no systemic hazard. At 3 W input, human 13C spectra were decoupled to a depth of about 5 cm while some Overhauser enhancement was sustained up to about 3 cm depth, without ill effect. The observation of glycogen in localized natural abundance 13C spectra of heart and muscle suggests that metabolites in the citric acid cycle should be observable noninvasively using 13C-labeled substrates.

  3. Frequency-stepped acquisition in nuclear magnetic resonance spectroscopy under magic angle spinning

    NASA Astrophysics Data System (ADS)

    Pell, Andrew J.; Clment, Raphale J.; Grey, Clare P.; Emsley, Lyndon; Pintacuda, Guido

    2013-03-01

    The nuclear magnetic resonance of paramagnetic solids is usually characterized by the presence of large chemical shifts and shift anisotropies due to hyperfine interactions. Frequently the resulting spectra cover a frequency range of several megahertz, which is greater than the bandwidth of commercially available radio-frequency (RF) probes, making it impossible to acquire the whole spectrum in a single experiment. In these cases it common to record a series of spectra, in which the probe is tuned to a different frequency for each, and then sum the results to give the "true" spectrum. While this method is very widely used on static samples, the application of frequency stepping under magic-angle spinning (MAS) is less common, owing to the increased complexity of the spin dynamics when describing the interplay of the RF irradiation with the mechanical rotation of the shift tensor. In this paper, we present a theoretical description, based on the jolting frame formalism of Caravatti et al. [J. Magn. Reson. 55, 88 (1983), 10.1016/0022-2364(83)90279-2], for describing the spin dynamics of a powder sample under MAS when subjected to a selective pulse of low RF-field amplitude. The formalism is used to describe the frequency stepping method under MAS, and under what circumstances the true spectrum is reproduced. We also present an experimental validation of the methodology under ultra-fast MAS with the paramagnetic materials LiMnPO4 and TbCsDPA.

  4. Quantum-state tomography of a single nuclear spin qubit of an optically manipulated ytterbium atom

    SciTech Connect

    Noguchi, Atsushi; Kozuma, Mikio; Eto, Yujiro; Ueda, Masahito

    2011-09-15

    A single Yb atom is loaded into a high-finesse optical cavity with a moving lattice, and its nuclear spin state is manipulated using a nuclear magnetic resonance technique. A highly reliable quantum state control with fidelity and purity greater than 0.98 and 0.96, respectively, is confirmed by the full quantum state tomography; a projective measurement with high speed (500 {mu}s) and high efficiency (0.98) is accomplished using the cavity QED technique. Because a hyperfine coupling is induced only when the projective measurement is operational, the long coherence times (T{sub 1}=0.49 s and T{sub 2}=0.10 s) are maintained.

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

    SciTech Connect

    Xiao, Yunlong; Zhang, Yong; Liu, Wenjian

    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)].

  6. 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).

  7. WURST-QCPMG sequence and "spin-lock" in 14N nuclear quadrupole resonance

    NASA Astrophysics Data System (ADS)

    Gregorovi?, Alan; Apih, Toma

    2013-08-01

    14N nuclear quadrupole resonance (NQR) is a promising method for the analysis of pharmaceuticals or for the detection of nitrogen based illicit compounds, but so far, the technique is still not widely used, mostly due to the very low sensitivity. This problem is already acute in the preliminary NQR stage, when a compound is being examined for the first time and the NQR frequencies are being searched for, by scanning a wide frequency range step-by-step. In the present work, we experimentally show how to increase the efficiency of this initial stage by using a combination of a wideband excitation achieved with frequency swept pulses (WURST) and a "spin-lock" state obtained with a quadrupolar-CPMG (QCPMG) sequence. In the first part we show that WURST pulses provide a much larger excitation bandwidth compared to common rectangular pulses. This increased bandwidth allows to increase the frequency step and reduces the total number of steps in a scanning stage. In the second part we show that the "spin-lock" decay time T2eff obtained with the WURST-QCPMG combination is practically identical with the T2eff obtained with the most common "spin-lock" sequence, the SLSE, despite a very different nature and length of excitation pulses. This allows for a substantial S/N increase through echo averaging in every individual step and really allows to exploit all the advantages of the wider excitation in the NQR frequency scanning stage. Our experimental results were obtained on a sample of trinitrotoluene, but identical behavior is expected for all compounds where a "spin-lock" state can be created.

  8. Prediction of nuclear spin based on the behavior of α-particle preformation probability

    NASA Astrophysics Data System (ADS)

    Ismail, M.; Adel, A.

    2013-11-01

    A realistic density-dependent nucleon-nucleon (NN) interaction with a finite-range exchange part which produces the nuclear matter saturation curve and the energy dependence of the nucleon-nucleus optical model potential is used to calculate the microscopic α-nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the α and daughter nuclei has been included in the folding model through the finite-range exchange part of the NN interaction. The α-decay half-lives have been determined using a microscopic potential within the semiclassical Wentzel-Kramers-Brillouin approximation in combination with the Bohr-Sommerfeld quantization condition. We systematically studied the preformation probability, Sα, for ten even-even and odd mass heavy nuclei from Po to No isotopes. We found that Sα has a regular behavior with N if the α particle emitted from adjacent isotopes comes from the same energy levels or from a group of levels, assuming that the order of levels in this group is not changed. Sudden increase in Sα is found when protons and neutrons holes exist below the Fermi levels. Based on the similarity in the behavior of Sα with the neutron number for two adjacent nuclei, we try to determine the unknown or doubted nuclear spins and parities or at least correlate spins of adjacent nuclei.

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

    NASA Astrophysics Data System (ADS)

    Behera, B.; Vias, 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.

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

    SciTech Connect

    Křístková, Anežka; Malkin, Vladimir G.; Komorovsky, Stanislav; Repisky, Michal; Malkina, Olga L.

    2015-03-21

    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.

  11. 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)

  12. Measuring the Spin Correlation of Nuclear Muon Capture in HELIUM-3.

    NASA Astrophysics Data System (ADS)

    McCracken, Dorothy Jill

    1996-06-01

    We have completed the first measurement of the spin correlation of nuclear muon capture in ^3 He: mu^- + ^3He to nu _{mu} + ^3 H. From this spin correlation, we can extract the induced pseudoscalar form factor, F_{ rm p}, of the weak charged nuclear current. This form factor is not well known experimentally. If nuclear muon capture were a purely leptonic weak interaction, the current would have no pseudoscalar coupling, and therefore F_{rm p} arises from QCD contributions. Since ^3He is a fairly well understood system, a precise measurement of F_{rm p} could provide a direct test of the theories which describe QCD at low energies. This experiment was performed at TRIUMF in Vancouver, BC, using a muon beam. We stopped unpolarized muons in a laser polarized target filled with ^3 He and Rb vapor. The muons were captured into atomic orbitals, forming muonic ^3He which was then polarized via collisions with the optically pumped Rb vapor. When polarized muons undergo nuclear capture in ^3He, the total capture rate is proportional to (1 + {rm A_ {v}P_{v}cos} theta) where theta is the angle between the muon polarization and the triton recoil direction, P_{rm v} is the muon vector polarization and A_ {rm v} is the vector analyzing power. The partially conserved axial current hypothesis (PCAC) predicts that A_{rm v} = 0.524 +/- 0.006 Our measurement of A_{rm v} is in agreement with this prediction: A_{rm v } = 0.604 +/- 0.093 (stat.) _sp{-.142}{+.112}(syst.). This thesis will describe the design, construction, and operation of the device which simultaneously served as a polarized target and a gridded ion chamber. The ion chamber apparatus enabled us to identify recoil tritons as well as determine their direction of motion. The directional information was obtained by fitting the shapes of the pulses generated by the tritons. In addition, this thesis will describe in detail the analysis of these pulses which resulted in a measurement of the raw forward/backward asymmetry of the triton recoil direction. This asymmetry was measured to a precision of 11.5%. With the techniques employed in this experiment, a clear path exists to obtaining a precise measurement of the induced pseudoscalar coupling of the charged weak nuclear current. Plans for a future run, in which we will improve upon these techniques, are underway.

  13. Korringa-Like Nuclear Spin-Lattice Relaxation in a 2DES at ν= 1/2

    NASA Astrophysics Data System (ADS)

    Tracy, L. A.; Pfeiffer, L. N.

    2005-03-01

    Via a resistively-detected NMR technique, the nuclear spin lattice relaxation time T1 of ^71Ga at low temperatures has been measured in a GaAs/AlGaAs heterostructure containing two weakly-coupled 2D electron systems (2DES), each at Landau level filling ν= 1/2. Incomplete electronic spin polarization, which has been reported previously [1,2] for low density 2DESs at ν= 1/2, should facilitate hyperfine- coupled nuclear spin relaxation owing to the presence of both electron spin states at the Fermi level. Within composite fermion theory, a Korringa law temperature dependence: T1T = constant, is expected for temperatures T<1 K. Our measurements made at temperatures in the range 35 mK nuclear spin relaxation mechanisms in this system.[1] I. V. Kukushkin, K. v. Klitzing, and K. Eberl. Phys. Rev. Lett. 82, 3665 (1999); A. E. Dementyev, et al., Phys. Rev. Lett. 83, 5074 (1999); S. Melinte, et al., Phys. Rev. Lett. 84, 354 (2000).[2] I.B. Spielman, L.A. Tracy, J.P. Eisenstein, L.N. Pfeiffer, K.W. West, condmat/0410092.This work was supported by the DOE, NSF, and NDSEG.

  14. Prediction of Nuclear Masses in the A=80 region of nuclei as a function of P and F-spin

    NASA Astrophysics Data System (ADS)

    Teymurazyan, A.; Aprahamian, A.; Georgieva, A.

    2002-11-01

    Predictions of nuclear masses far from stability are one of the challenges to present day network calculations in simulating various astrophysical scenarios and yielding the appropriate elemental abundances. Various groups have shown that complex nuclear structure properties as well as nuclear masses are correlated with the valence number of neutrons and protons. One such parameter is the promiscuity factor P and a related approach is that of F-spin. Both parameters are used to describe known measurements and used to predict via interpolation methods the masses of nuclei presently unknown in the laboratory. Here we show the exact relationship between P and F-spin in an attempt to strengthen structure based prediction methods for nuclear masses of interest in both the rp-process and the r-process.

  15. Nuclear Jacobi and Poincar 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 Poincar 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 Poincar 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 Schrdinger equation whose solutions are used to calculate the most probable deformations associated with the nuclear Jacobi and Poincar transitions. We discuss selected aspects of the new description focusing on the critical-spin values for both types of these transitions.

  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. Spin-dipole nuclear matrix elements for double beta decays and astro-neutrinos

    NASA Astrophysics Data System (ADS)

    Ejiri, H.; Soukouti, N.; Suhonen, J.

    2014-02-01

    Spin-dipole (SD) nuclear matrix elements (NMEs) M±(SD2) for unique first forbidden β± 2-→0+ ground-state-to-ground-state transitions are studied by using effective microscopic two-nucleon interactions in realistic single-particle model spaces. The observed values of the NMEs Mexp±(SD2) are compared with the values of the single-quasiparticle NMEs Mqp±(SD2) without nucleon spin-isospin (στ) correlation and the QRPA NMEs MQRPA±(SD2) with the στ correlation. The observed SD matrix elements are found to be reduced by the factor k≈0.2 with respect to Mqp±(SD2) and by the factor kNM≈0.5 with respect to MQRPA±(SD2). We then infer that the SD NME is reduced considerably partly by the nucleon στ correlations and partly by other non-nucleonic and nucleonic correlations which are not explicitly included in the QRPA. Impact of the found reduction factors on the magnitudes of the NMEs involved in neutrino-less double beta decays and astro-neutrino interactions are discussed.

  18. A mononuclear transition metal single-molecule magnet in a nuclear spin-free ligand environment.

    PubMed

    Fataftah, Majed S; Zadrozny, Joseph M; Rogers, Dylan M; Freedman, Danna E

    2014-10-01

    The high-spin pseudotetrahedral complex [Co(C3S5)2](2-) exhibits slow magnetic relaxation in the absence of an applied dc magnetic field, one of a small number of mononuclear complexes to display this property. Fits to low-temperature magnetization data indicate that this single-molecule magnet possesses a very large and negative axial zero-field splitting and small rhombicity. The presence of single-molecule magnet behavior in a zero-nuclear spin ligand field offers the opportunity to investigate the potential for this molecule to be a qubit, the smallest unit of a quantum information processing (QIP) system. However, simulations of electron paramagnetic resonance (EPR) spectra and the absence of EPR spectra demonstrate that this molecule is unsuitable as a qubit due to the same factors that promote single molecule magnet behavior. We discuss the influence of rhombic and axial zero-field splitting on QIP applications and the implications for future molecular qubit syntheses. PMID:25198379

  19. Theoretical study of the nuclear spin-molecular rotation coupling for relativistic electrons and non-relativistic nuclei.

    PubMed

    Aucar, Ignacio A; Gómez, Sergio S; Ruiz de Azúa, Martín C; Giribet, Claudia G

    2012-05-28

    A theoretical study of the relation between the relativistic formulation of the nuclear magnetic shielding and spin-rotation tensors is presented. To this end a theoretical expression of the relativistic spin-rotation tensor is formulated, considering a molecular Hamiltonian of relativistic electrons and non-relativistic nuclei. Molecular rotation effects are introduced considering the terms of the Born-Oppenheimer decomposition, which couple the electrons and nuclei dynamics. The loss of the simple relation linking both spectral parameters in the non-relativistic formulation is further analyzed carrying out a perturbative expansion of relativistic effects by means of the linear response within the elimination of the small component approach. It is concluded that relativistic effects on the spin-rotation tensor are less important than those of the nuclear magnetic shielding tensor. PMID:22667552

  20. 23Na Nuclear Spin-Lattice Relaxation Studies of Na2Ni2TeO6

    NASA Astrophysics Data System (ADS)

    Itoh, Yutaka

    2015-06-01

    We report on 23Na NMR studies of the honeycomb lattice antiferromagnet Na2Ni2TeO6 by 23Na nuclear spin-echo techniques. The 23Na nuclear spin-lattice relaxation rate 1/23T1 exhibits critical divergence near the Nel temperature TN = 26 K, a narrow critical region, and the critical exponent w = 0.34 in 1/23T1 ? (T/TN - 1)-w for Na2Ni2TeO6, and TN = 18 K for Na2(Ni0.5Cu0.5)2TeO6. Although the uniform magnetic susceptibility of Na2Ni2TeO6 exhibits a broad maximum at 35 K, which is the characteristic of low-dimensional spin systems, the NMR results indicate a three-dimensional criticalphenomenon near the Nel temperature.

  1. Features of influence of dc magnetic field pulses on a nuclear spin echo in magnets

    NASA Astrophysics Data System (ADS)

    Mamniashvili, G. I.; Gegechkori, T. O.; Akhalkatsi, A. M.; Gavasheli, C. A.

    2012-06-01

    Signal intensities of a two-pulse nuclear spin echo as a function of parameters of dc magnetic field pulses are measured in the series of materials: Li0.5Fe2.5-xZnxO4 (x < 0.25) (enriched in 57Fe isotope to 96.8%), NiMnSb, Co2MnSi, La1-????MnO3 (x = 0.2; 0.25) and polycrystalline Co. Two types of dependences of these signals on a supplying time of such pulses with respect to the times of the exciting RF pulses are found. The mechanisms of influence of a domain structure and a dynamic frequency shift on the observed features of the investigated signals are discussed.

  2. Metabolomic studies of patient material by high-resolution magic angle spinning nuclear magnetic resonance spectroscopy.

    PubMed

    Keun, Hector

    2014-01-01

    Magic angle spinning nuclear magnetic resonance (MAS-NMR) spectroscopy offers a convenient means for the rapid determination of metabolic profiles from intact malignant tissues with high resolution. The implementation of MAS-NMR spectroscopy requires minimal sample processing, hence being compatible with complementary histological or biochemical analyses. The metabolites routinely detected in (1)H MAS-NMR spectra can simultaneously inform on many of the metabolic alterations that characterize malignant cells, including altered choline metabolism and the so-called Warburg effect. Clinical MAS-NMR profiles have been attributed with diagnostic or prognostic value, correlating to disease subtype, tumor stage/grade, response to chemotherapy, and patient survival. Herein, the scientific rationale behind MAS-NMR and its utility for translational cancer research and patient stratification is summarized. Moreover, a basic protocol for the analysis of tumor samples by MAS-NMR spectroscopy is detailed. PMID:24924139

  3. 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 hslash 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.

  4. 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 8נ10(-5)per second over 100milliseconds, 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 37060minutes was achieved at 2kelvin. 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 9kilometres 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

  5. 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.

  6. Fully Relativistic Calculations of Faraday and Nuclear Spin-Induced Optical Rotation in Xenon.

    PubMed

    Iklinen, Suvi; Lantto, Perttu; Vaara, Juha

    2012-01-10

    Nuclear spin-induced optical rotation (NSOR) arising from the Faraday effect may constitute an advantageous novel method for the detection of nuclear magnetization. We present first-principles nonrelativistic and relativistic, two- and four-component, basis-set limit calculations of this phenomenon for xenon. It is observed that only by utilization of relativistic methods may one qualitatively reproduce experimental liquid-state NSOR data. Relativistic effects lower the results by 50% as compared to nonrelativistic values. Indeed, relativistic Hartree-Fock calculations at the four-component or exact two-component (X2C) level account for the discrepancy between experimental results and earlier nonrelativistic theory. The nuclear magnetic shielding constant of traditional nuclear magnetic resonance as well as the Verdet constant parametrizing optical rotation due to an external magnetic field were also calculated. A comparison between results obtained using Hartree-Fock and density-functional theory methods at relativistic and nonrelativistic levels, as well as coupled cluster methods at the nonrelativistic level, was carried out. Completeness-optimized basis sets were employed throughout, for the first time in fully relativistic calculations. Full relativity decreases the Verdet constant by 4%. X2C theory decreases the absolute value of NSOR by 10-20% as compared to the four-component data, while for Verdet constants, the results are only slightly smaller than the fully relativistic values. For both properties, two-component calculations decrease the computational time by roughly 90%. Density-functional methods yield substantially larger values of NSOR than the Hartree-Fock theory or experiments. Intermolecular interactions are found to decrease NSOR and, hence, compensate for the electron correlation effect. PMID:26592871

  7. 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 μm 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 δ‰ relative to NIST SRM 3133 Hg standard where δAHg = [(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 δ198Hg, δ200Hg, δ202Hg, δ204Hg define a mass- dependent fractionation sequence, where as the δ199Hg and δ201Hg depart from the mass- dependent fractionation line and indicate an excess of the odd-N isotopes. The magnitude of the deviation (ΔAHg where A=199 or 201) as obtained by difference between the measured δ199Hg and δ201Hg 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 Δ199Hg /Δ201Hg 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 Δ199Hg than in Δ201Hg 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 Δ201Hg /Δ199Hg 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.

  8. Field-induced spin reorientation in [Fe/Cr ] n multilayers studied by nuclear resonance reflectivity

    NASA Astrophysics Data System (ADS)

    Andreeva, M.; Gupta, A.; Sharma, G.; Kamali, S.; Okada, K.; Yoda, Y.

    2015-10-01

    We present depth-resolved nuclear resonance reflectivity studies of the magnetization evolution in [57Fe(3nm ) /Cr (1.2 nm ) ] 10 multilayer under applied external field. The measurements have been performed at the station BL09XU of SPring-8 at different values of the external field (0-1500 Oe). We apply the joint fit of the delayed reflectivity curves and the time spectra of the nuclear resonance reflectivity measured at different grazing angles for enhancement of the depth resolution and reliability of results. We show that the azimuth angle, which is used in all papers devoted to the magnetization profile determination, has a more complicated physical sense due to the partially coherent averaging of the scattering amplitudes from magnetic lateral domains. We describe how to select the true azimuth angle from the determined "effective azimuth angle." Finally we obtain the noncollinear twisted magnetization depth profiles where the spin-flop state appears sequentially in different 57Fe layers at increasing applied field.

  9. Spin gap behavior in Cu2Sc2Ge4O13 studied using Sc45 nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Lue, C. S.; Kuo, C. N.; Su, T. H.; Redhammer, G. J.

    2007-01-01

    We report the results of a Sc45 nuclear magnetic resonance (NMR) study on the quasi-one-dimensional compound Cu2Sc2Ge4O13 at temperatures between 4 and 300K . This material has been a subject of current interest due to indications of spin gap behavior. The temperature-dependent NMR shift exhibits a character of low-dimensional magnetism with a negative broad maximum at Tmax?170K . Below Tmax , the NMR shifts and spin lattice relaxation rates clearly indicate activated responses, confirming the existence of a spin gap in Cu2Sc2Ge4O13 . The experimental NMR data can be well fitted to the spin dimer model, yielding a spin gap value of about 275K which is close to the 25meV peak found in the inelastic neutron scattering measurement. A detailed analysis further points out that the nearly isolated dimer picture is proper for the understanding of spin gap nature in Cu2Sc2Ge4O13 .

  10. Floquet-Magnus expansion for general N-coupled spins systems in magic-angle spinning nuclear magnetic resonance spectra

    NASA Astrophysics Data System (ADS)

    Mananga, Eugene Stephane; Charpentier, Thibault

    2015-04-01

    In this paper we present a theoretical perturbative approach for describing the NMR spectrum of strongly dipolar-coupled spin systems under fast magic-angle spinning. Our treatment is based on two approaches: the Floquet approach and the Floquet-Magnus expansion. The Floquet approach is well known in the NMR community as a perturbative approach to get analytical approximations. Numerical procedures are based on step-by-step numerical integration of the corresponding differential equations. The Floquet-Magnus expansion is a perturbative approach of the Floquet theory. Furthermore, we address the " ? -encoding" effect using the Floquet-Magnus expansion approach. We show that the average over " ? " angle can be performed for any Hamiltonian with ? symmetry.

  11. 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, Bjrn; 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 13T/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

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

    SciTech Connect

    Mueller, K.T. California Univ., Berkeley, CA . 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.

  13. Studies of phospholipid hydration by high-resolution magic-angle spinning nuclear magnetic resonance.

    PubMed Central

    Zhou, Z; Sayer, B G; Hughes, D W; Stark, R E; Epand, R M

    1999-01-01

    A sample preparation method using spherical glass ampoules has been used to achieve 1.5-Hz resolution in 1H magic-angle spinning (MAS) nuclear magnetic resonance (NMR) spectra of aqueous multilamellar dispersions of 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC), serving to differentiate between slowly exchanging interlamellar and bulk water and to reveal new molecular-level information about hydration phenomena in these model biological membranes. The average numbers of interlamellar water molecules in multilamellar vesicles (MLVs) of DOPC and POPC were found to be 37.5 +/- 1 and 37.2 +/- 1, respectively, at a spinning speed of 3 kHz. Even at speeds as high as 9 kHz, the number of interlamellar waters remained as high as 31, arguing against dehydration effects for DOPC and POPC. Both homonuclear and heteronuclear nuclear Overhauser enhancement spectroscopy (NOESY and HOESY) were used to establish the location of water near the headgroup of a PC bilayer. 1H NMR comparisons of DOPC with a lipid that can hydrogen bond (monomethyldioleoylphosphatidylethanolamine, MeDOPE) showed the following trends: 1) the interlamellar water resonance was shifted to lower frequency for DOPC but to higher frequency for MeDOPE, 2) the chemical shift variation with temperature for interlamellar water was less than that of bulk water for MeDOPE MLVs, 3) water exchange between the two lipids was rapid on the NMR time scale if they were mixed in the same bilayer, 4) water exchange was slow if they were present in separate MLVs, and 5) exchange between bulk and interlamellar water was found by two-dimensional exchange experiments to be slow, and the exchange rate should be less than 157 Hz. These results illustrate the utility of ultra-high-resolution 1H MAS NMR for determining the nature and extent of lipid hydration as well as the arrangement of nuclei at the membrane/water interface. PMID:9876150

  14. The Spin Dependence of Nuclear Muon Capture by Laser Polarized HELIUM-3.

    NASA Astrophysics Data System (ADS)

    Bogorad, Paul Lev

    1995-01-01

    Using the muon beam at TRIUMF, we have made the first measurement of the spin dependence of the reaction: mu^- + ^3He tonu +^3H. This spin dependence is quite sensitive to the induced pseudoscalar form factor, F_{P}, a piece of the weak charged nuclear current of ^3He about which, experimentally, relatively little is known. The ratio of F_{P} to F _{A}, the axial vector form factor, is predicted by the partially conserved axial current hypothesis (PCAC) and the Goldberger-Treiman relation. Thus, a measurement of F_{P} will test our understanding of strong interactions at low energies. The rate of nuclear muon capture in ^3 He is proportional to (1+A_{v }P_{v} {rm cos} theta), where theta is the angle between the muon polarization and the direction of the triton recoil, P_{v} is the muon vector polarization and A_{v } is the vector analyzing power, a preliminary value for which is: A_{v} = .604 +/-.093(stat.)_sp{-142}{+112 }(system.). This value is in agreement with the PCAC prediction of: A_{v}=.524 +/-.006. A measure of the strength of our technique is that the raw forward/backward asymmetry in the triton recoil direction was measured to 11.5% of itself. The design, construction and operation of the device that served both as a polarized target and as a detector for the recoil tritons is the main emphasis of this thesis. The detector, a gridded ion chamber, was incorporated inside a 5 liter target that was filled with 8 atmospheres of ^3He, 100 torr of N_2, and 6 grams of Rb. Muons stopped in the target formed muonic helium atoms and were polarized by collisions with Rb atoms that were optically pumped with lasers. The ion chamber produced clean signals despite operating under the severe conditions required for optical pumping. The direction of the tritons was determined by fitting the shapes of the ionization pulses. Future improvements of our technique appear to provide the most promising avenue to improved understanding of the induced pseudoscalar coupling, F_ {P}, as well as the induced pseudoscalar coupling of the proton, g_{P}. .

  15. Photochemically induced dynamic nuclear polarization in photosystem I of plants observed by 13C magic-angle spinning NMR.

    PubMed

    Alia; Roy, Esha; Gast, Peter; van Gorkom, Hans J; de Groot, Huub J M; Jeschke, Gunnar; Matysik, Jrg

    2004-10-13

    Photochemically induced dynamic nuclear polarization (photo-CIDNP) has been observed in photosystem I of spinach by (13)C magic angle spinning solid-state NMR under continuous illumination with white light. An almost complete set of chemical shifts of the aromatic ring carbons of a single Chl a molecule has been obtained which is assigned to the P2-cofactor of the primary electron donor P700. Since all light-induced (13)C NMR signals appear to be emissive, a predominance of the three-spin mixing mechanism over the differential decay mechanism is proposed. The origin of the strong contribution of the three-spin mixing mechanism and the differences with photosystem II are discussed. PMID:15469277

  16. 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

  17. Effect of zero field splitting interactions on the paramagnetic relaxation enhancement of nuclear spin relaxation rates in solution

    NASA Astrophysics Data System (ADS)

    Sharp, Robert R.

    1993-01-01

    The enhancement of nuclear spin relaxation rate R1m that is produced by paramagnetic metal ions in solution (the NMR-PRE) has been investigated for electron spin systems with S=1 using recently developed relaxation theory that incorporates both Zeeman and zero field splitting (zfs) interactions of arbitrary magnitude in the electron spin Hamiltonian. The zfs interaction gives rise to important qualitative features which have no analog in the Zeeman-limit theory. The three principal physical phenomena responsible for these effects are (1) alterations in the geometry of the magnetic dipole-dipole coupling energy due to requantization of the electron spin from laboratory to molecular axes; (2) the crossing or ``pinching'' of spin energy levels that occurs in the regime of field strengths between the zfs and Zeeman limits; and (3) an effective magnetic field dependence in the reorientational correlation time that results from a change in the appropriate definition of this quantity in the intermediate regime. In the zfs limit and in the intermediate regime, the field dispersion profile depends strongly on the position of the nuclear spin with respect to the molecular coordinate axes. For equatorial positions of the nuclear spin, the principle qualitative feature of the dispersion profile is a strong increase in R1m with increasing field strength coupled, in most cases, with a shallow local R1m maximum; both features are centered near the cross-over field between the limits. For axial positions, the profile exhibits a feature that is superficially similar to those characteristic of Zeeman-limit theory, but which is fundamentally different in quantitative properties and in physical origin. As a test of theoretical predictions, the experimental magnetic field profile of the NMR-PRE of the hexaquo-Ni(II) cation, an S=1 model system that has previously been studied extensively, has been reinterpreted. It is shown that the major qualitative features of the experimental field profile result specifically from physical effects of the zfs interaction and are closely related to the phenomenon of requantization of the electron spin in the intermediate regime.

  18. Influence of the Nuclear Electric Quadrupolar Interaction on the Coherence Time of Hole and Electron Spins Confined in Semiconductor Quantum Dots

    NASA Astrophysics Data System (ADS)

    Hackmann, J.; Glasenapp, Ph.; Greilich, A.; Bayer, M.; Anders, F. B.

    2015-11-01

    The real-time spin dynamics and the spin noise spectra are calculated for p and n -charged quantum dots within an anisotropic central spin model extended by additional nuclear electric quadrupolar interactions and augmented by experimental data. Using realistic estimates for the distribution of coupling constants including an anisotropy parameter, we show that the characteristic long time scale is of the same order for electron and hole spins strongly determined by the quadrupolar interactions even though the analytical form of the spin decay differs significantly consistent with our measurements. The low frequency part of the electron spin noise spectrum is approximately 1 /3 smaller than those for hole spins as a consequence of the spectral sum rule and the different spectral shapes. This is confirmed by our experimental spectra measured on both types of quantum dot ensembles in the low power limit of the probe laser.

  19. 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.

  20. Carbon-13 CP-MAS nuclear magnetic resonance studies of teas.

    PubMed

    Martnez-Richa, Antonio; Joseph-Nathan, Pedro

    2003-05-01

    13C CP-MAS NMR spectra of green and black tea were obtained and assigned based on the solid-state NMR spectra of tropolone, (+)-catechin hydrate, gallic acid, caffeine and flavone derivatives. The peak shape and chemical shifts observed for carbonyl carbons in CP-MAS spectra of teas indicate the existence of different chemical species, mainly free phenollic acids and ester derivatives of flavonoids. The peak patterns allow to establish differences between both teas. PMID:12763559

  1. Motions and electrostatic interactions in natural and semisynthetic myoglobins: a carbon-13 nuclear magnetic resonance study

    SciTech Connect

    Maskalick, D.G.

    1984-01-01

    It is expected that the internal motions of amino acid side chains and protein backbone segments influence and are in turn affected by charge-charge and related interactions, steric constraints, hydrophobic forces, and hydrogen bonding. As an initial test of this theory /sup 13/C-enriched glycine, alanine, and isoleucine have been substituted for the amino terminal valine of sperm whale myoglobin using semisynthetic techniques. /sup 13/C-NMR has been used to analyze the motions of the side chain and the protonation state of the alpha amino group as a function of pH. The addition of a single methyl group to the side chain can alter the alpha amino pK value by as much as 0.3 pH units indicating a delicately balanced set of change-charge interactions between the alpha amino group and the rest of the protein. Further evidence in support of the state theory was found upon examination of the internal motions of seven of nine isoleucine vectors. These motions were extracted from natural abundance /sup 13/C-NMR relaxation data. The results suggest a strong possibility that concerted motions are important. Also, an increase in temperature from 32/sup 0/C to 52/sup 0/C leads to an electrostatically driven tightening of the myoglobin structure as evidenced by no significant increase in motion amplitude of most of the vectors.

  2. 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

  3. Infrared spectroscopic investigation of nuclear spin conversion in solid CH4.

    PubMed

    Sugimoto, Takeru; Yamakawa, Koichiro; Arakawa, Ichiro

    2015-12-14

    Infrared spectra of solid CH4 were studied in the ?3 and ?4 vibrational regions. The phase I crystal around 30 K showed broad absorption bands, whereas the phase II crystal at 6.9-10.3 K exhibited splitting of these bands after annealing above 20 K. The split peaks were assigned to the librating and almost freely rotating molecules in phase II on the basis of the peak spacings and time evolution of the peak intensities. From the quantitative analysis of the temporal changes of the R(0) and R(1) peak intensities, the relaxation rates of the numbers of molecules with J = 0 (I = 2) and J = 1 (I = 1) were determined in the temperature range of 6.9-10.3 K. We fitted the function resulting from a combination of direct and indirect relaxation processes mediated by phonons to the temperature dependence of these rates and obtained the activation energies of the indirect process: C ? 36 K. Since this value is higher than the energies of perturbed J = 2 states relative to the J = 1 state, we argue that the nuclear spin conversion through the J = 3 state also takes place. PMID:26671373

  4. Spurious finite-size instabilities in nuclear energy density functionals: Spin channel

    NASA Astrophysics Data System (ADS)

    Pastore, A.; Tarpanov, D.; Davesne, D.; Navarro, J.

    2015-08-01

    Background: It has been recently shown that some Skyrme functionals can lead to nonconverging results in the calculation of some properties of atomic nuclei. A previous study has pointed out a possible link between these convergence problems and the appearance of finite-size instabilities in symmetric nuclear matter (SNM) around saturation density. Purpose: We show that the finite-size instabilities not only affect the ground-state properties of atomic nuclei, but they can also influence the calculations of vibrational excited states in finite nuclei. Method: We perform systematic fully-self consistent random phase approximation (RPA) calculations in spherical doubly magic nuclei. We employ several Skyrme functionals and vary the isoscalar and isovector coupling constants of the time-odd term s .Δ s . We determine critical values of these coupling constants beyond which the RPA calculations do not converge because the RPA stability matrix becomes nonpositive. Results: By comparing the RPA calculations of atomic nuclei with those performed for SNM we establish a correspondence between the critical densities in the infinite system and the critical coupling constants for which the RPA calculations do not converge. Conclusions: We find a quantitative stability criterion to detect finite-size instabilities related to the spin s .Δ s term of a functional. This criterion could be easily implemented in the standard fitting protocols to fix the coupling constants of the Skyrme functional.

  5. Infrared spectroscopic investigation of nuclear spin conversion in solid CH4

    NASA Astrophysics Data System (ADS)

    Sugimoto, Takeru; Yamakawa, Koichiro; Arakawa, Ichiro

    2015-12-01

    Infrared spectra of solid CH4 were studied in the ?3 and ?4 vibrational regions. The phase I crystal around 30 K showed broad absorption bands, whereas the phase II crystal at 6.9-10.3 K exhibited splitting of these bands after annealing above 20 K. The split peaks were assigned to the librating and almost freely rotating molecules in phase II on the basis of the peak spacings and time evolution of the peak intensities. From the quantitative analysis of the temporal changes of the R(0) and R(1) peak intensities, the relaxation rates of the numbers of molecules with J = 0 (I = 2) and J = 1 (I = 1) were determined in the temperature range of 6.9-10.3 K. We fitted the function resulting from a combination of direct and indirect relaxation processes mediated by phonons to the temperature dependence of these rates and obtained the activation energies of the indirect process: C ? 36 K. Since this value is higher than the energies of perturbed J = 2 states relative to the J = 1 state, we argue that the nuclear spin conversion through the J = 3 state also takes place.

  6. Spin-mapping of coal structures with ESE and ENDOR (Electron-Nuclear Double Resonance)

    SciTech Connect

    Belford, R.L.; Clarkson, R.B.

    1989-03-01

    Our Laboratory is presently engaged in developing a method to model sulfur-containing compounds in whole coal. It has been established that most of the organic sulfur in coal exists in the form of aromatic groups known as thiophenes. Sulfur-containing aromatic compounds such as thiophene, tetraphenylthiophene and thianthrene were adsorbed onto silica-alumina catalyst surfaces were used as models to emulate coal's anisotropic nature and abundance of unpaired electron spin density. The spectroscopic techniques used were Electron Paramagnetic Resonance (EPR), Electron-Nuclear Double Resonance (ENDOR). EPR spectroscopy is a well established method to characterize g-matrix anisotropy in transition metal compounds. With increased resolution, EPR has become very useful for characterizing the small but still detectable g-matrix anisotropy in organic systems such as coal and the model systems for coal. ENDOR spectroscopy involves the inducement of NMR transitions of the nearby protons while detecting them with an EPR detection scheme which is several orders of magnitude more sensitive than using a NMR detection scheme. Analysis of the ENDOR spectra produced hyperfine information which is characteristic of these sulfur-containing systems. This information will be needed to resolve anisotropic hyperfine spectral features attributable to sulfur content in the analysis of coal macerals. 2 refs., 3 figs.

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

    NASA Astrophysics Data System (ADS)

    Aucar, I. Agustn; Gmez, Sergio S.; Giribet, Claudia G.; Ruiz de Aza, Martn 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. Gmez, J. I. Melo, C. G. Giribet, and M. C. Ruiz de Aza, 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. Breit interaction effects in relativistic theory of the nuclear spin-rotation tensor.

    PubMed

    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)], 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. PMID:24028107

  9. Deuterium Nuclear Spin-Lattice Relaxation Times and Quadrupolar Coupling Constants in Isotopically Labeled Saccharides

    NASA Astrophysics Data System (ADS)

    Bose-Basu, Bidisha; Zajicek, Jaroslav; Bondo, Gail; Zhao, Shikai; Kubsch, Meredith; Carmichael, Ian; Serianni, Anthony S.

    2000-06-01

    13C and 2H spin-lattice relaxation times have been determined by inversion recovery in a range of site-specific 13C- and 2H-labeled saccharides under identical solution conditions, and the data were used to calculate deuterium nuclear quadrupolar coupling constants (2H NQCC) at specific sites within cyclic and acyclic forms in solution. 13C T1 values ranged from ?0.6 to 8.2 s, and 2H T1 values ranged from ?79 to 450 ms, depending on molecular structure (0.4 M sugar in 5 mM EDTA (disodium salt) in 2H2O-depleted H2O, pH 4.8, 30C). In addition to providing new information on 13C and 2H relaxation behavior of saccharides in solution, the resulting 2H1 NQCC values reveal a dependency on anomeric configuration within aldopyranose rings, whereas 2H NQCC values at other ring sites appear less sensitive to configuration at C1. In contrast, 2H NQCC values at both anomeric and nonanomeric sites within aldofuranose rings appear to be influenced by anomeric configuration. These experimental observations were confirmed by density functional theory (DFT) calculations of 2H NQCC values in model aldopyranosyl and aldofuranosyl rings.

  10. Nuclear spin dependence of the reaction of H(3)+ with H2. II. Experimental measurements.

    PubMed

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

    2011-05-21

    The nuclear spin dependence of the chemical reaction H(3)(+)+ H(2) → H(2) + 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-H(2) (p-H(2)) enrichment. The ratio of the rates of the proton hop (k(H)) and hydrogen exchange (k(E)) reactions α ≡ k(H)/k(E) is inferred from the observed p-H(3)(+) fraction as a function of p-H(2) fraction using steady-state chemical models. Measurements have been performed both in uncooled (T(kin) ∼ 350 K) and in liquid-nitrogen-cooled (T(kin) ∼ 135 K) plasmas, marking the first time this reaction has been studied at low temperature. The value of α has been found to decrease from 1.6 ± 0.1 at 350 K to 0.5 ± 0.1 at 135 K. PMID:21599063

  11. 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: farhod.nozirov@gmail.com; Stachw, Micha?; Kupka, Teobald 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)

  12. Thermal entanglement of a coupled electronic spins system: interplay between an external magnetic field, nuclear field and spin-orbit interaction

    NASA Astrophysics Data System (ADS)

    Guerrero M., Roberto J.; Rojas, F.

    2015-06-01

    We have studied the thermal entanglement as a function of the temperature for a two-qubits Heisenberg spins system; we have included Dzyaloshinskii-Moriya interaction (DM), an external magnetic field (EMF) and hyperfine interaction due to the nuclear field of the surrounding nuclei. A critical value for the EMF was found, around mT, which characterizes two regimes of behavior of the thermal entanglement. Our results show that the DM term acts as a facilitator for the entanglement because it prolongs the nonzero thermal entanglement for larger temperatures. We found that the concurrence as a function of the temperature has a local maximum, for values of the magnetic field larger than the critical field. We also show that the critical temperature follows a polynomial growth as a function of the DM term, with characteristic behavior , and the hyperfine field implies a critical temperature as a function of the field variance, of the form . We show that in this system, the entanglement measure by the concurrence and the one-spin polarization observable exhibit opposite behavior, providing a method to obtain the entanglement from the measurement of an observable.

  13. Molecular orbital calculations of /sup 13/C-/sup 13/C and /sup 1/H-/sup 1/H nuclear spin-spin coupling constants

    SciTech Connect

    Severson, M.L.

    1984-01-01

    Theoretical studies are presented for the conformational dependencies of vicinal /sup 13/C-/sup 13/C coupling constants within a variety of saturated and unsaturated molecular frameworks. Using the molecular orbital approach of Blizzard and Santry, it is shown that three distinct patterns of dihedral angle versus /sup 3/H/sub CC/sup contract/ coupling are produced, depending upon the degree of double bonding present within the direct coupling path. By means of calculations that involve modifying the various exchange integrals, two of these coupling patterns are found to depend on sigma-..pi.. exchange. A rationalization of the origin of these coupling patterns is presented. In all systems studied, the orbital and dipolar contributions to the vicinal coupling constant are calculated to be negligible compared to the Fermi contact mechanism except in conjugated systems. The FP/INDO molecular orbital method is employed in the investigation of substitutent effects on /sup 1/H-/sup 1/H coupling constants in substituted ethanes, ethylenes, and benzenes. Substituent effects are simulated by varying the (1/2)(I + A) INDO parameters on two different types of pseudoatoms, one essentially a pseudo-hydrogen and the other involving 2s and 2p orbitals on two centers. A review of the theory of nuclear spin-spin coupling is presented.

  14. Observation of Zero-Point Quantum Fluctuations of a Single-Molecule Magnet through the Relaxation of its Nuclear Spin Bath

    NASA Astrophysics Data System (ADS)

    Morello, A.; Milln, A.; de Jongh, L. J.

    2014-03-01

    A single-molecule magnet placed in a magnetic field perpendicular to its anisotropy axis can be truncated to an effective two-level system, with easily tunable energy splitting. The quantum coherence of the molecular spin is largely determined by the dynamics of the surrounding nuclear spin bath. Here we report the measurement of the nuclear spin-lattice relaxation rate 1/T1n in a single crystal of the single-molecule magnet Mn12-ac, at T ?30 mK in perpendicular fields B? up to 9 T. The relaxation channel at B?0 is dominated by incoherent quantum tunneling of the Mn12-ac spin S, aided by the nuclear bath itself. However for B?>5 T we observe an increase of 1/T1n by several orders of magnitude up to the highest field, despite the fact that the molecular spin is in its quantum mechanical ground state. This striking observation is a consequence of the zero-point quantum fluctuations of S, which allow it to mediate the transfer of energy from the excited nuclear spin bath to the crystal lattice at much higher rates. Our experiment highlights the importance of quantum fluctuations in the interaction between an "effective two-level system" and its surrounding spin bath.

  15. Syntheses of carbon-13 labeled protoporphyrin-IX for spectroscopic studies of heme proteins

    SciTech Connect

    Fujinari, E.M.

    1985-01-01

    The development of various methodologies for synthesis of selectively tailored protoporphyrin-IX dimethyl ester are presented. The iron(II) complex of protoporphyrin-IX is the heme, the prosthetic group for Hb, Mb, cytochromes and peroxidases. The significance of this research is to provide direct means to establish definitive carbon-13 NMR assignments of heme proteins in order to study not only the structure-function relationships, but also protein dynamics of these vital systems. Carbon-13 labeling at the beta-vinyl position was first achieved by ozonolysis of protoporphyrin-IX dimethyl ester. Column LC method were used to first isolate 2,4-diformyldeuteroporphyrin-IX dimethyl ester. Concomitantly, monofomyl-monovinyl porphyrins were obtained as a mixture of two isomers. This mixture was separated by MPLC or prep HPLC to afford the isomerically pure products, Spirographis porphyrin dimethyl ester and Iso-Spirographis porphyrin dimethyl ester. A Wittig reaction to each of these porphyrins with /sup 13/C-methyltriphenylphosphonium iodide gave 2,4-bis(/sup 13/C/sub 2/)-vinyl protoporphyrin-IX dimethyl ester, 2-(/sup 13/C/sub 2/)-vinyl protoporphyrin-IX dimethyl ester, and the 4-(/sup 13/C/sub 2/)-vinyl protoporphyrin-IX dimethyl ester, respectively.

  16. 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

  17. High-resolution nuclear magnetic resonance spectroscopy of biological tissues using projected magic angle spinning.

    PubMed

    Martin, Rachel W; Jachmann, Rebecca C; Sakellariou, Dimitris; Nielsen, Ulla Gro; Pines, Alexander

    2005-08-01

    High-resolution NMR spectra of materials subject to anisotropic broadening are usually obtained by rotating the sample about the magic angle, which is 54.7 degrees to the static magnetic field. In projected magic angle spinning (p-MAS), the sample is spun about two angles, neither of which is the magic angle. This provides a method of obtaining isotropic spectra while spinning at shallow angles. The p-MAS experiment may be used in situations where spinning the sample at the magic angle is not possible due to geometric or other constraints, allowing the choice of spinning angle to be determined by factors such as the shape of the sample, rather than by the spin physics. The application of this technique to bovine tissue samples is demonstrated as a proof of principle for future biological or medical applications. PMID:16032677

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

    SciTech Connect

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

    2015-01-28

    Long-lived nuclear spin states have a relaxation time much longer than the longitudinal relaxation time T{sub 1}. 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 {sup 13}CH{sub 3} 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.

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

    PubMed

    SivaRanjan, Uppala; Ramachandran, Ramesh

    2014-02-01

    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(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(2) experimental results and could serve as a test-bed for distinguishing coherent/incoherent effects in solid-state NMR. PMID:24511916

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

    SciTech Connect

    SivaRanjan, Uppala; Ramachandran, Ramesh

    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.

  1. Nuclear magnetic resonance-paramagnetic relaxation enhancements: Influence of spatial quantization of the electron spin when the zero-field splitting energy is larger than the Zeeman energy

    NASA Astrophysics Data System (ADS)

    Abernathy, S. M.; Miller, J. C.; Lohr, L. L.; Sharp, R. R.

    1998-09-01

    Dissolved paramagnetic ions generally provide an efficient mechanism for the relaxation of nuclear spins in solution, a phenomenon called the nuclear magnetic resonance-paramagnetic relaxation enhancement (NMR-PRE). Metal ions with electron spins S?1 exhibit rich NMR relaxation phenomena originating in the properties of the zero-field splitting (zfs) interaction, which vanishes for spin-1/2 ions but which is nonzero for S?1 ions in site symmetry lower than cubic. For S?1 ions in the vicinity of the zfs-limit, i.e., at magnetic-field strengths low enough that the zfs energy exceeds the Zeeman energy, the NMR-PRE depends strongly on the detailed structure of the electron spin energy levels as well as on the spatial quantization of the spin motion. It is shown theoretically and experimentally that the NMR-PRE produced by integer spins can be influenced strongly by the small intradoublet zero-field splittings, i.e., the splittings between the components of the non-Kramers doublets, which are produced by noncylindrical components of the crystal field potential. These small splittings produce relatively low-frequency oscillations in the dipolar field associated with (the spin component along the molecule-fixed ? axis). These motions decouple the nuclear spin from the electron spin, thereby depressing, in some cases very strongly, the NMR-PRE. The presence of a relatively small Zeeman field, comparable in magnitude to the intradoublet spacing but small compared to the larger interdoublet zfs splittings, causes a major change in the spin wave functions which has profound effects on the motions of the electron spin. When the Zeeman energy exceeds the small zfs splitting, the oscillatory motion of damps out, with the result that the electron spin couples more effectively to the nuclear spin, providing a more efficient NMR relaxation pathway. NMR-PRE data are presented for the S=1 complex Ni(II)(o-pda)2Cl2 (o-pda=ortho-phenylenediamine) which confirm the importance of the splitting of the mS=1 non-Kramers doublet on the NMR relaxation efficiency. The zfs E-parameter was measured from the NMR data to be |E|=0.26 cm-1. The S=2 spin system, Mn(III)-tetraphenylporphyrin sulfonate, exhibits a related phenomenon which arises from the effects of a small zfs splitting, ??2, of the mS=2 non-Kramers doublet that is caused by a fourfold rotational component of the crystal field potential. The splitting ??2 was measured from NMR data to be 0.20 cm-1.

  2. Anisotropic 2H-nuclear magnetic resonance spin-lattice relaxation in cerebroside- and phospholipid-cholesterol bilayer membranes.

    PubMed Central

    Siminovitch, D. J.; Ruocco, M. J.; Olejniczak, E. T.; Das Gupta, S. K.; Griffin, R. G.

    1988-01-01

    The axially symmetric powder pattern 2H-nuclear magnetic resonance (NMR) lineshapes observed in the liquid crystalline phase of pure lipid or lipid/cholesterol bilayers are essentially invariant to temperature, or, equivalently, to variations in the correlation times characterizing C-2H bond reorientations. In either of these melted phases, where correlation times for C-2H bond motions are shorter than 10(-7) s, information on the molecular dynamics of the saturated hydrocarbon chain would be difficult to obtain using lineshape analyses alone, and one must resort to other methods, such as the measurement of 2H spin-lattice relaxation rates, in order to obtain dynamic information. In pure lipid bilayers, the full power of the spin-lattice relaxation technique has yet to be realized, since an important piece of information, namely the orientation dependence of the 2H spin-lattice relaxation rates is usually lost due to orientational averaging of T1 by rapid lateral diffusion. Under more favorable circumstances, such as those encountered in the lipid/cholesterol mixtures of this study, the effects of orientational averaging by lateral diffusion are nullified, due to either a marked reduction (by at least an order of magnitude) in the diffusion rate, or a marked increase in the radii of curvature of the liposomes. In either case, the angular dependence of 2H spin-lattice relaxation is accessible to experimental study, and can be used to test models of molecular dynamics in these systems. Simulations of the partially recovered lineshapes indicate that the observed T1 anisotropies are consistent with large amplitude molecular reorientation of the C-2H bond among a finite number of sites. Furthermore, from the observed orientation dependence of the 2H spin-lattice relaxation rates, we conclude that order director fluctuations cannot provide the dominant relaxation pathway for acyl chain deuterons. PMID:3207831

  3. 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.

  4. On the carbon-13 chemical shift tensors of bent-core mesogens

    NASA Astrophysics Data System (ADS)

    Dong, Ronald Y.; Zhang, J.; Fodor-Csorba, K.

    2006-01-01

    Solid state NMR techniques are used to study bent-shape achiral molecules which can form a new type of mesophases, known as 'banana' or B phases. In particular, a recent method called SUPER is applied to two solids of this type of polar mesogens, rotating at the magic angle, to extract carbon-13 chemical shift anisotropy tensors. They are useful not only to aid 13C peak assignments in the isotropic state, but are necessary for accounting the observed chemical shifts of various carbon sites, resided on the bent-core aromatic part, in the spectrum of an aligned mesophase. An example to extract ordering information is given for one of the studied mesogens.

  5. CARBON-13 NMR OR SOLID STATE HYDROCARBONS AND RELATED SUBSTANCES-FINAL REPORT

    SciTech Connect

    Grant, David M.

    2007-08-16

    CARBON-13 NMR OR SOLID STATE HYDROCARBONS AND RELATED SUBSTANCES-FINAL REPORT Abstract: During recent years we have been engaged in SSNMR (Solid State NMR) structural studies of unusual tetracyanoethylene compounds with unusually long bonds between four carbons centered on two electrons. The chemical shift tensors reflect these unusual atomic arrangements. Quantum chemistry predicts the strange tensor shifts. The three dimensional molecular structure may be determined in this manner. Despite significant advances in structural determination from powder diffraction data, NMR shift tensors argument the structural accuracy and also suggest initial trial structures. Mixtures of polymorphs are difficult to analyze with diffraction methods whereas the SSNMR methods are able to characterize such mixtures in one anothers presence. Spectroscopic developments in our laboratory include SSNMR INADEQUATE and FIREMAT methods. We have used these methods to study the 13C and 15N NMR explosive CL-20.

  6. Absorption of carbon 13-labeled rice in milk by infants during acute gastroenteritis.

    PubMed

    Lifschitz, C H; Torun, B; Chew, F; Boutton, T W; Garza, C; Klein, P D

    1991-04-01

    To determine whether rice cereal could be used to complement a cow milk-based diet in the nutritional management of infants with acute diarrhea, we assessed its digestion and absorption in eight affected male infants, 69 to 131 days of age. They received cow milk formula with 5.4% lactose (diluted 1:1 with water and precooked rice cereal) 5 to 22 hours after admission and rehydration. The first feeding consisted of milk diluted with carbon 13-enriched rice cereal. A 48-hour fecal collection and balance study was performed. Rice cereal was reasonably well absorbed (84.0% to 95.8%) by seven of the eight infants. The study was repeated in seven of the infants after they had recovered. Our results indicated that rice cereal is well absorbed by young infants with acute diarrhea and that it is an adequate nutrient supplement for this patient population. PMID:2007925

  7. Diagnosis of Helicobacter pylori by carbon-13 urea breath test using a portable mass spectrometer

    PubMed Central

    Sreekumar, J; France, N; Taylor, S; Matthews, T; Turner, P; Bliss, P; Watson, AJM

    2015-01-01

    Context: In the non-invasive detection of markers of disease, mass spectrometry is able to detect small quantities of volatile markers in exhaled air. However, the problem of size, expense and immobility of conventional mass spectrometry equipment has restricted its use. Now, a smaller, less expensive, portable quadrupole mass spectrometer system has been developed. Helicobacter pylori has been implicated in the development of chronic gastritis, gastric and duodenal ulcers and gastric cancer. Objectives: To compare the results obtained from the presence of H. pylori by a carbon-13 urea test using a portable quadrupole mass spectrometer system with those from a fixed mass spectrometer in a hospital-based clinical trial. Methods: Following ethical approval, 45 patients attending a gastroenterology clinic at the Royal Liverpool University Hospital exhaled a breath sample into a Tedlar gas sampling bag. They then drank an orange juice containing urea radiolabelled with carbon and 30?min later gave a second breath sample. The carbon-13 content of both samples was measured using both quadrupole mass spectrometer systems. If the post-drink level exceeded the pre-drink level by 3% or more, a positive diagnosis for the presence of H. pylori was made. Results: The findings were compared to the results using conventional isotope ratio mass spectrometry using a laboratory-based magnetic sector instrument off-site. The results showed agreement in 39 of the 45 patients. Conclusions: This study suggests that a portable quadrupole mass spectrometer is a potential alternative to the conventional centralised testing equipment. Future development of the portable quadrupole mass spectrometer to reduce further its size and cost is indicated, together with further work to validate this new equipment and to enhance its use in mass spectrometry diagnosis of other medical conditions.

  8. Indirect 1H NMR characterization of H2@C60 nitroxide derivatives and their nuclear spin relaxation.

    PubMed

    Li, Yongjun; Lei, Xuegong; Li, Xia; Lawler, Ronald G; Murata, Yasujiro; Komatsu, Koichi; Turro, Nicholas J

    2011-12-14

    (1)H NMR of two H(2)@C(60) nitroxide derivatives has been characterized indirectly by reducing to their corresponding hydroxylamines. Nuclear spin relaxation of the endohedral H(2) and external protons of the H(2)@C(60) nitroxide and its corresponding hydroxylamine were measured and analyzed. The observed spectra are consistent with negligible scalar coupling between the unpaired electron and the endo-H(2). An unexpectedly large bimolecular relaxivity induced in the hydroxylamine by the corresponding nitroxide can be explained by rapid hydrogen atom transfer between the two species. PMID:22027815

  9. Efficient calculation of nuclear spin-rotation constants from auxiliary density functional theory.

    PubMed

    Zuniga-Gutierrez, Bernardo; Camacho-Gonzalez, Monica; Bendana-Castillo, Alfonso; Simon-Bastida, Patricia; Calaminici, Patrizia; Köster, Andreas M

    2015-09-14

    The computation of the spin-rotation tensor within the framework of auxiliary density functional theory (ADFT) in combination with the gauge including atomic orbital (GIAO) scheme, to treat the gauge origin problem, is presented. For the spin-rotation tensor, the calculation of the magnetic shielding tensor represents the most demanding computational task. Employing the ADFT-GIAO methodology, the central processing unit time for the magnetic shielding tensor calculation can be dramatically reduced. In this work, the quality of spin-rotation constants obtained with the ADFT-GIAO methodology is compared with available experimental data as well as with other theoretical results at the Hartree-Fock and coupled-cluster level of theory. It is found that the agreement between the ADFT-GIAO results and the experiment is good and very similar to the ones obtained by the coupled-cluster single-doubles-perturbative triples-GIAO methodology. With the improved computational performance achieved, the computation of the spin-rotation tensors of large systems or along Born-Oppenheimer molecular dynamics trajectories becomes feasible in reasonable times. Three models of carbon fullerenes containing hundreds of atoms and thousands of basis functions are used for benchmarking the performance. Furthermore, a theoretical study of temperature effects on the structure and spin-rotation tensor of the H(12)C-(12)CH-DF complex is presented. Here, the temperature dependency of the spin-rotation tensor of the fluorine nucleus can be used to identify experimentally the so far unknown bent isomer of this complex. To the best of our knowledge this is the first time that temperature effects on the spin-rotation tensor are investigated. PMID:26374014

  10. Efficient calculation of nuclear spin-rotation constants from auxiliary density functional theory

    NASA Astrophysics Data System (ADS)

    Zuniga-Gutierrez, Bernardo; Camacho-Gonzalez, Monica; Bendana-Castillo, Alfonso; Simon-Bastida, Patricia; Calaminici, Patrizia; Kster, Andreas M.

    2015-09-01

    The computation of the spin-rotation tensor within the framework of auxiliary density functional theory (ADFT) in combination with the gauge including atomic orbital (GIAO) scheme, to treat the gauge origin problem, is presented. For the spin-rotation tensor, the calculation of the magnetic shielding tensor represents the most demanding computational task. Employing the ADFT-GIAO methodology, the central processing unit time for the magnetic shielding tensor calculation can be dramatically reduced. In this work, the quality of spin-rotation constants obtained with the ADFT-GIAO methodology is compared with available experimental data as well as with other theoretical results at the Hartree-Fock and coupled-cluster level of theory. It is found that the agreement between the ADFT-GIAO results and the experiment is good and very similar to the ones obtained by the coupled-cluster single-doubles-perturbative triples-GIAO methodology. With the improved computational performance achieved, the computation of the spin-rotation tensors of large systems or along Born-Oppenheimer molecular dynamics trajectories becomes feasible in reasonable times. Three models of carbon fullerenes containing hundreds of atoms and thousands of basis functions are used for benchmarking the performance. Furthermore, a theoretical study of temperature effects on the structure and spin-rotation tensor of the H12C-12CH-DF complex is presented. Here, the temperature dependency of the spin-rotation tensor of the fluorine nucleus can be used to identify experimentally the so far unknown bent isomer of this complex. To the best of our knowledge this is the first time that temperature effects on the spin-rotation tensor are investigated.

  11. Optimal control of fast and high-fidelity quantum gates with electron and nuclear spins of a nitrogen-vacancy center in diamond

    NASA Astrophysics Data System (ADS)

    Chou, Yi; Huang, Shang-Yu; Goan, Hsi-Sheng

    2015-05-01

    A negatively charged nitrogen-vacancy (NV) center in diamond has been recognized as a good solid-state qubit. A system consisting of the electronic spin of the NV center and hyperfine-coupled nitrogen and additionally nearby carbon nuclear spins can form a quantum register of several qubits for quantum information processing or as a node in a quantum repeater. Several impressive experiments on the hybrid electron and nuclear spin register have been reported, but fidelities achieved so far are not yet at or below the thresholds required for fault-tolerant quantum computation (FTQC). Using quantum optimal control theory based on the Krotov method, we show here that fast and high-fidelity single-qubit and two-qubit gates in the universal quantum gate set for FTQC, taking into account the effects of the leakage state, nearby noise qubits, and distant bath spins, can be achieved with errors less than those required by the threshold theorem of FTQC.

  12. Analytic approach to nuclear rotational states and the role of spin: A minimal model

    NASA Astrophysics Data System (ADS)

    Bentz, W.; Arima, A.; Richter, A.; Wambach, J.

    2014-02-01

    Background: The scissors mode is a rotational mode of isovector character in deformed nuclei. Together with the isoscalar rotation, it is the prominent collective mode at low excitation energies. Purpose: We use a simple field theory model to investigate the role of the nucleon spin for the magnetic sum rules associated with the low-lying scissors mode. Special emphasis is put on the coupling of the spin part of the M1 operator to the scissors mode. Methods: We apply the mean-field approximation and random phase approximation to a model Hamiltonian based on a simple quadrupole-quadrupole interaction. The effects of the spin-orbit interaction are included in the mean-field Hamiltonian. Ward-Takahashi relations are used to derive the M1 sum rules. Results: The presence of the spin-orbit interaction leads to interference terms in the inverse energy weighted sum rule. It is shown that the low-lying scissors mode, which is generated by the isovector combination of proton and neutron total angular momenta, gives the main contribution to the spectral sum for this case. Conclusions: The basic concept of the scissors mode as an isovector vibrational rotation remains valid in the presence of the nucleon spin. The inverse energy weighted sum rule, however, receives nontrivial modifications because of interference terms.

  13. Optically detected hyperfine splitting and optical nuclear-spin hyperpolarization of the ^209Bi donor in ^natSi

    NASA Astrophysics Data System (ADS)

    Sekiguchi, T.; Steger, M.; Yang, A.; Saeedi, K.; Thewalt, M. L. W.; Riemann, H.; Abrosimov, N. V.; Ntzel, N.

    2010-03-01

    Among the group-V donors in silicon, bismuth (^209Bi) has by far the largest hyperfine constant due to its large binding energy. So far, however, there has been no attempt to see the hyperfine splitting in the Bi bound exciton transition. We show a well-resolved zero-field hyperfine splitting, and while the hyperfine splitting under magnetic field is not well resolved an optical hyperpolarization of the Bi nuclear spin (I = 9/2) is observed by studying the temperature dependence of the PL spectra. This nonresonant optical nuclear hyperpolarization is similar to one observed recently for ^31P using EPR, and we propose a new model for its origin.

  14. Body-fixed relativistic molecular Hamiltonian and its application to nuclear spin-rotation tensor: Linear molecules

    NASA Astrophysics Data System (ADS)

    Xiao, Yunlong; Liu, Wenjian

    2013-07-01

    The relativistic molecular Hamiltonian written in the body-fixed frame of reference is the basis for high-precision calculations of spectroscopic parameters involving nuclear vibrations and/or rotations. Such a Hamiltonian that describes electrons fully relativistically and nuclei quasi-relativistically is just developed for semi-rigid nonlinear molecules [Y. Xiao and W. Liu, J. Chem. Phys. 138, 134104 (2013)], 10.1063/1.4797496. Yet, the formulation should somewhat be revised for linear molecules thanks to some unusual features arising from the redundancy of the rotation around the molecular axis. Nonetheless, the resulting isomorphic Hamiltonian is rather similar to that for nonlinear molecules. Consequently, the relativistic formulation of nuclear spin-rotation (NSR) tensor for linear molecules is very much the same as that for nonlinear molecules. So is the relativistic mapping between experimental NSR and NMR.

  15. What Do Nuclear Spin Temperatures Tell Us About The Origin Of Comets? A Multi-molecule Study

    NASA Astrophysics Data System (ADS)

    Villanueva, Geronimo; Mumma, M. J.; Bonev, B. P.; DiSanti, M. A.; Magee-Sauer, K.; Gibb, E. L.; Paganini, L.; Radeva, Y. L.

    2012-10-01

    Comets are true remnants of our primordial Solar System, and provide unique clues to its formation and evolution, including the delivery of organics and water to our planet. A key indicator stored in the molecular structure of the nuclear ices is the spin temperature (Tspin), derived from spin-isomeric ratios (Rspin, e.g. ortho/para). At the time when cometary ices formed, the prevailing temperature defined the relative abundance of the different spin-isomeric species, and herewith Rspin and Tspin are normally treated as remnant thermometers probing the formation environments. Most of our knowledge of this indicator comes from measurements of ortho-para ratios in water and NH2, suggesting a common Tspin near 30K. This information is based on a restricted sample of comets, and the measurements are particularly sensitive to the molecular modeling technique and adopted spectral database. Here, we present new methodologies for extracting spin temperatures from ethane (C2H6), methane (CH4), and methanol (CH3OH), and describe advanced new models for ortho/para water (H2O) and ammonia (NH3). Our H2O analysis is based on the most complete fluorescence radiative transfer model to date, which incorporates 1,200 million transitions including those originating from high-energy levels that are activated in comets via non-resonance cascade. In a similar fashion, we developed non-resonance fluorescence models for NH3 and HCN, and quantum band models for the ?7 band of C2H6 and ?3 band of CH3OH. All models respect spin symmetry non-conversion radiative rules, and make use of a realistic Solar spectrum for the computation of fluorescence pumps. We applied these new methods to derive spin-isomeric ratios for H2O, CH4, C2H6, CH3OH and NH3 from three high-quality cometary datasets: 1) C/2007 W1 (Boattini), 2) C/2001 A2 (LINEAR), and 3) 8P/Tuttle. We compare our results with the measured organic compositions for these comets, and present possible formation and evolution scenarios.

  16. Experimental evidence for the role of cross-relaxation in proton nuclear magnetic resonance spin lattice relaxation time measurements in proteins.

    PubMed Central

    Sykes, B D; Hull, W E; Snyder, G H

    1978-01-01

    Proton nuclear magnetic resonance (NMR) spin lattice relaxation time (T1) and spin-spin relaxation time (T2) measurements are presented for a number of proteins with molecular weights spanning the range of 6,500-150,000 daltons. These measurements provide experimental evidence for the role of cross-relaxation in 1H NMR T1 measurements in proteins. The relationship between these measurements and the theory recently presented by Kalk and Berendsen is discussed. The results indicate that cross-relaxation dominates the T1 measurements for the larger proteins, even at relatively low resonance frequencies such as 100 MHz. PMID:623862

  17. Density functional theory calculations of the nuclear magnetic resonance spin-Hamiltonian parameters for two polyamines of prostate tissue: spermidine and spermine

    NASA Astrophysics Data System (ADS)

    Atieh, Z.; Allouche, A. R.; Graveron-Demilly, D.; Fauvelle, F.; Aubert-Frcon, M.

    2009-10-01

    1H nuclear magnetic resonance (NMR) spin-Hamiltonian parameters: chemical shifts ? and spin-spin coupling constants J have been calculated for the two polyamines: spermidine and spermine present in prostate tissue. Molecules in the gas phase as well as in solution in water have been investigated using density functional theory calculations. From calculated ? and J values, NMR spectra have been simulated and compared to the experimental ones we acquired at 400 MHz for each polyamine in solution in D2O. From these comparisons, reliable NMR parameters are proposed for spermidine and spermine, among which the J constants were until now unknown for these two molecules.

  18. Evolution of nuclear shapes at high spins as determined by lifetime measurements

    SciTech Connect

    Johnson, N.

    1986-01-01

    Lifetime measurements of high spin states are obtained by the Doppler-shift recoil-distance method. Transition quadrupole moments are extracted from these data. Expanding on earlier experimental work, lifetime and moment of inertia measurements were made for /sup 172/W. The data for transition quadrupole moments for the yrast states reveals an unexpected drop at high spin which can be explained by the simultaneous alignment of h/sub 9/2/ protons and i/sub 13/2/ neutrons. This conclusion is supported by moment of inertia measurements which show evidence of a 3-band crossing. 9 refs., 10 figs., 2 tabs. (DWL)

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

    NASA Astrophysics Data System (ADS)

    Lunde, Anders Mathias; Lpez-Mons, 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.

  20. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning.

    PubMed

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264GHz with 1.5W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized (13)C NMR signals in the 100-200 range are demonstrated with DNP at 25K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30K can be achieved with helium consumption rates below 1.3l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states. PMID:26920835

  1. Low-temperature dynamic nuclear polarization with helium-cooled samples and nitrogen-driven magic-angle spinning

    NASA Astrophysics Data System (ADS)

    Thurber, Kent; Tycko, Robert

    2016-03-01

    We describe novel instrumentation for low-temperature solid state nuclear magnetic resonance (NMR) with dynamic nuclear polarization (DNP) and magic-angle spinning (MAS), focusing on aspects of this instrumentation that have not been described in detail in previous publications. We characterize the performance of an extended interaction oscillator (EIO) microwave source, operating near 264 GHz with 1.5 W output power, which we use in conjunction with a quasi-optical microwave polarizing system and a MAS NMR probe that employs liquid helium for sample cooling and nitrogen gas for sample spinning. Enhancement factors for cross-polarized 13C NMR signals in the 100-200 range are demonstrated with DNP at 25 K. The dependences of signal amplitudes on sample temperature, as well as microwave power, polarization, and frequency, are presented. We show that sample temperatures below 30 K can be achieved with helium consumption rates below 1.3 l/h. To illustrate potential applications of this instrumentation in structural studies of biochemical systems, we compare results from low-temperature DNP experiments on a calmodulin-binding peptide in its free and bound states.

  2. Hyperfine interaction in InAs/GaAs self-assembled quantum dots: dynamical nuclear polarization versus spin relaxation

    NASA Astrophysics Data System (ADS)

    Krebs, Olivier; Eble, Benoît; Lemaître, Aristide; Voisin, Paul; Urbaszek, Bernhard; Amand, Thierry; Marie, Xavier

    2008-10-01

    We report on the influence of the hyperfine interaction on the optical orientation of singly charged excitons X in self-assembled InAs/GaAs quantum dots. All measurements were carried out on individual quantum dots studied by micro-photoluminescence at low temperature. We show that the hyperfine interaction leads to an effective partial spin relaxation, under 50 kHz modulated excitation polarization, which becomes, however, strongly inhibited under steady optical pumping conditions because of dynamical nuclear polarization. This optically created magnetic-like nuclear field can become very strong (up to ˜4 T) when it is generated in the direction opposite to a longitudinally applied field, and exhibits then a bistability regime. This effect is very well described by a theoretical model derived in a perturbative approach, which reveals the key role played by the energy cost of an electron spin flip in the total magnetic field. Finally, we emphasize the similarities and differences between X and X trions with respect to the hyperfine interaction, which turn out to be in perfect agreement with the theoretical description. To cite this article: O. Krebs et al., C. R. Physique 9 (2008).

  3. New application of proton nuclear spin relaxation unraveling the intermolecular structural features of low-molecular-weight organogel fibers.

    PubMed

    Bouguet-Bonnet, Sabine; Yemloul, Mehdi; Canet, Daniel

    2012-06-27

    Proton nuclear spin relaxation has been for the first time extensively used for a structural and dynamical study of low-molecular-weight organogels. The gelator in the present study is a modified phenylalanine amino acid bearing a naphthalimide moiety. From T(1) (spin-lattice relaxation time in the laboratory frame) and T(1?) (spin-lattice relaxation time in the rotating frame) measurements, it is shown that the visible gelator NMR spectrum below the liquid-gel transition temperature corresponds to a so-called isotropic compartment, where gelator molecules behave as in a liquid phase but exchange rapidly with the molecules constituting the gel structure. This feature allows one to derive, from accessible parameters, information about the gel itself. Nuclear Overhauser effect spectroscopy (NOESY) experiments have been exploited in view of determining not only cross-relaxation rates but also specific longitudinal rates. The whole set of relaxation parameters (at 25 C) leads to a correlation time of 5 ns for gelator molecules within the gel structure and 150 ps for gelator molecules in the isotropic phase. This confirms, on one hand, the flexibility of the organogel fibers and, on the other hand, the likely presence of clusters in the isotropic phase. Concerning cross-relaxation rates, a thorough theoretical investigation in multispin systems of direct and relayed correlations in a NOESY spectrum allows one to make conclusions about contacts (around 2-3 ) not only between naphtalimide moieties of different gelator molecules but also between the phenyl ring and the naphtalimide moiety again of different gelator molecules. As a result, not only is the head-to-tail structure of amino acid columns confirmed but also the entangling of nearby columns by the naphthalimide moieties is demonstrated. PMID:22663178

  4. Dipolar nuclear spin relaxation in liquids and plane fluids undergoing chemical reactions

    NASA Astrophysics Data System (ADS)

    Fries, P. H.

    We describe the correlated translational and rotational relative brownian motions of two reacting groups of atoms, alternatively bound and free, by the normalized solutions of a set of coupled diffusion equations. Under equilibrium conditions we calculate the spectral densities j(?) characteristic of the fluctuations of the intermolecular dipolar coupling between spins of these diffusing groups of atoms. When ?? << 1, where ? is the translational correlation time, the form of the spectral density j2(?) in three-dimensional liquids is j2(0) - ?3?1/2. The coefficient ?3 is independent of the molecular local order, of the diffusional rotation speed of the spin-carrying groups of atoms and of their association and dissociation rates. In plane fluids, when ?? << 1, the spectral density j(0)(?) may be written as -a2 ln (??) where the dependence of a2 on the average relative distribution of the interacting spins varies with the rate of the chemical reactions. In both three- and two-dimensional fluids spectral densities show an ?-3/2 or ?-2 behaviour for ?? >> 1 according to the magnitude of the association rate of the reacting groups of atoms. In liquid glycerol we analyse the low- and high-frequency limits of the experimental proton relaxation rate 1/T1 and 1/T1? measured by Harmon, Harmon and Burnett, and Lenk. We also discuss the proton spin-lattice relaxation times measured by Kleinberg and Silbernagel in layered intercalation compounds TiS2-NH3 and TaS2-NH3.

  5. 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.

  6. QCD Nuclear g-factor and the Spin-Statistics Theorem

    NASA Astrophysics Data System (ADS)

    Ward, Thomas

    2015-04-01

    Consideration of the composite three-quark nucleon spin structure and its Pauli spin-statistics follows a new QCD g-factor with implications for the magnetic dipole moments of nucleons and their form factors. The reformulation of the nucleon magnetic moments using the new QCD nucleon g-factor is shown to be in striking agreement with global polarized and unpolarized e-p scattering data using the Sachs electric and magnetic form factors, thus reconciling long standing discrepancies between measurements. Additionally, the introduction of QCD isospin symmetry breaking (ISB) strange quarks terms contained within the meson-baryon exchange currents allow the partially conserved EM axial currents to be restored as well as providing a precise measure of the strange quark probabilities of the nucleons. Work performed under the auspices of US Department of Energy.

  7. Nuclear quadrupole resonance of spin 3/2 and entangled two-qubit states

    NASA Astrophysics Data System (ADS)

    Furman, G.; Goren, S. D.; Meerovich, V.; Sokolovsky, V.

    2015-10-01

    A single spin-3/2, possessing a quadrupole moment and placed in a non-uniform electric field, is isomorphic to a system of two spins of 1/2, which can be represented as two qubits. To create these qubits, the degeneracy of the energy levels is removed by applying two radio-frequency fields with different phases and directions. The properties of entanglement between two qubits are studied. We analyze the concurrence, the entropy of entanglement, and fluctuations of the entropy in the pure and mixed states. Concurrence and entropy of entanglement in a mixed state increase with decreasing temperature and approach to their values in a pure state. For a nucleus Cu in high temperature superconductor {{YBa}}2{{Cu}}3{{{O}}}7-? , the estimation of the temperature, at which entanglement appears, gives T ?slant 0.8 ?K.

  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. OROCHI experiment: Laser spectroscopy of RI atoms in superfluid helium for measurements of nuclear spins and electromagnetic moments

    NASA Astrophysics Data System (ADS)

    Furukawa, Takeshi

    2014-09-01

    We have been developing a new laser spectroscopy technique named as OROCHI (Optical RI-atom Observation in Condensed Helium as Ion-catcher) for measurements of nuclear spins and electromagnetic moments of low yield exotic radioisotopes (RIs). In this technique, we use superfluid helium (He II) liquid as a stopping material of RI beam in which in-situ laser spectroscopy of the RI atoms stopped in He II is carried out. The characteristic features of He II, i.e. high trapping efficiency of He II liquid for accelerated ion beams and the characteristics of atomic spectra in He II, enables us to measure the nuclear spins and moments of the extremely low yield RIs. So far, we have demonstrated the feasibility of our method to deduce the nuclear spins and moments with stable Rb, Cs, Ag and Au isotopes supplied into He II by laser sputtering technique. In addition, we have also succeeded in observing laser-radiowave/microwave double resonance signals of 84-87Rb atoms injected into He II as energetic ion beam. In these on-line experiment, the 84-87Rb isotope beams (intensity: up to 105 particles/s) were provided with RIPS beamline in RIKEN, and introduced into He II filled in a cryostat. Special care was taken in controlling the stopping position of injected Rb isotopes. Aluminum energy degraders of varied thickness from 0 to 0.8 mm were placed upstream of the beam injection window of the He II cryostat for optimizing the stopping position The 84-87Rb atoms stopped and then neutralized in He II were optically pumped and polarized with circularly polarized pumping laser light whose wavelength were tuned to 780 nm, D1 absorption line of Rb atoms in He II. The polarized atoms were subjected to irradiation of radiowave or microwave, and then we demonstrated the double resonance spectroscopy for observing the Zeeman transition of 84-87Rb atoms and the hyperfine transition of 87Rb, respectively In this presentation we will show the details of OROCHI technique and the present status of our development, in particular the result of the recent on-line experiment.

  10. Identifying and Quantifying Actinide Radiation Damage in Ceramics with Radiological Magic-Angle Spinning Nuclear Magnetic Resonance

    SciTech Connect

    Farnan, Ian; Cho, Herman; Weber, William J.

    2007-07-01

    In the characterisation of amorphization or local disordering due to actinide radiation damage, nuclear magnetic resonance (NMR) spectroscopy is attractive because it is element specific and equally sensitive to local structure in crystalline and amorphous materials. Here, we have applied high-resolution solid-state NMR spectroscopy (magic-angle spinning) to radiation damaged natural minerals containing {sup 238}U/{sup 232}Th to determine the 'number fraction' of amorphous material (fa) through spin-counting techniques. In samples with a known alpha dose, the number of atoms displaced per alpha decay may be determined from an integration of the spectrum. A protocol for performing similar radiological magic-angle spinning experiments on plutonium containing ceramic samples with an activity of > 5 GBq is described. Results obtained have allowed data from ancient, radiation damaged mineral samples of ZrSiO{sub 4} ({sup 238}U/{sup 232}Th) to be compared with modern {sup 238}/{sup 239}Pu doped ceramic ZrSiO{sub 4} samples. The number of atomic displacements per alpha particle from {sup 239}Pu is similar to that for {sup 238}U/{sup 232}Th (4980 {+-} 300/{alpha}). At lower {alpha}-doses there are significant differences in the amorphous volume fraction (observed by density and X-ray diffraction) and the number fraction of displaced atoms (as measured by NMR) as a function of cumulative dose. These differences arise from local density considerations that manifest themselves in the local structure of the amorphous and crystalline phases. Using ab initio simulations of the damaged crystalline and amorphous regions, the magnetic response of these structures and hence the NMR shifts can be compared with experiment to reveal the nature of radiation induced changes occurring at the local scale. (authors)

  11. 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.

  12. Laser spectroscopy of atoms in superfluid helium for the measurement of nuclear spins and electromagnetic moments of radioactive atoms

    NASA Astrophysics Data System (ADS)

    Fujita, T.; Furukawa, T.; Imamura, K.; Yang, X. F.; Hatakeyama, A.; Kobayashi, T.; Ueno, H.; Asahi, K.; Shimoda, T.; Matsuo, Y.

    2015-11-01

    A new laser spectroscopic method named "OROCHI (Optical RI-atom Observation in Condensed Helium as Ion catcher)" has been developed for deriving the nuclear spins and electromagnetic moments of low-yield exotic nuclei. In this method, we observe atomic Zeeman and hyperfine structures using laser-radio-frequency/microwave double-resonance spectroscopy. In our previous works, double-resonance spectroscopy was performed successfully with laser-sputtered stable atoms including non-alkali Au atoms as well as alkali Rb and Cs atoms. Following these works, measurements with 84-87Rb energetic ion beams were carried out in the RIKEN projectile fragment separator (RIPS). In this paper, we report the present status of OROCHI and discuss its feasibility, especially for low-yield nuclei such as unstable Au isotopes.

  13. Spectrally resolved hyperfine interactions between polaron and nuclear spins in organic light emitting diodes: Magneto-electroluminescence studies

    NASA Astrophysics Data System (ADS)

    Crooker, S. A.; Liu, F.; Kelley, M. R.; Martinez, N. J. D.; Nie, W.; Mohite, A.; Nayyar, I. H.; Tretiak, S.; Smith, D. L.; Ruden, P. P.

    2014-10-01

    We use spectrally resolved magneto-electroluminescence (EL) measurements to study the energy dependence of hyperfine interactions between polaron and nuclear spins in organic light-emitting diodes. Using layered devices that generate bright exciplex emission, we show that the increase in EL emission intensity I due to small applied magnetic fields of order 100 mT is markedly larger at the high-energy blue end of the EL spectrum (?I/I 11%) than at the low-energy red end (4%). Concurrently, the widths of the magneto-EL curves increase monotonically from blue to red, revealing an increasing hyperfine coupling between polarons and nuclei and directly providing insight into the energy-dependent spatial extent and localization of polarons.

  14. Study of Nuclear Bound States Using Mean-Field Woods-Saxon and Spin-Orbit Potentials

    NASA Astrophysics Data System (ADS)

    Pahlavani, M. R.; Alavi, S. A.

    2012-09-01

    The neutron single-particle bound states as solutions of radial Schrdinger equation for the central Woods-Saxon potential together with spin-orbit interaction and centrifugal terms have been obtained analytically. By introducing new variable and using Taylor expansion, the differential equation has been transformed to solvable hypergeometric type. This differential equation has also been solved using Nikiforov-Uvarov (NU) method. Neutron single-particle states have been derived as self-adjoint form of hypergeometric series. By means of boundary conditions, which implies eigenvalue condition as complicated relation between energy eigenvalues and parameters of nuclear potential, the neutron single-particle energy eigenvalues have been derived using graphical method. To examine method, numerical results in special cases of S states are evaluated. Results obtained using this method are in satisfactory agreements with available numerical solutions.

  15. The Conformation of NAD+ Bound to Lactate Dehydrogenase Determined by Nuclear Magnetic Resonance with Suppression of Spin Diffusion

    NASA Astrophysics Data System (ADS)

    Vincent, Sebastien J. F.; Zwahlen, Catherine; Post, Carol Beth; Burgner, John W.; Bodenhausen, Geoffrey

    1997-04-01

    We have reinvestigated the conformation of NAD+ bound to dogfish lactate dehydrogenase (LDH) by using an NMR experiment that allows one to exploit nuclear Overhauser effects to determine internuclear distances between pairs of protons, without perturbation of spin-diffusion effects from other protons belonging either to the cofactor or to the binding pocket of the enzyme. The analysis indicates that the structure of bound NAD+ is in accord with the conformation determined in the solid state by x-ray diffraction for the adenosine moiety, but deviates significantly from that of the nicotinamide. The NMR data indicate conformational averaging about the glycosidic bond of the nicotinamide nucleotide. In view of the strict stereospecificity of catalysis by LDH and the conformational averaging of bound NAD+ that we infer from solution-state NMR, we suggest that LDH binds the cofactor in both syn and anti conformations, but that binding interactions in the syn conformation are not catalytically productive.

  16. Spin-Echo Nuclear Magnetic Resonance Evidence for Complexing of Sodium Ions in Muscle, Brain, and Kidney

    PubMed Central

    Cope, Freeman W.

    1970-01-01

    Na+ in muscle, brain, and kidney is shown by spin-echo nuclear magnetic resonance (NMR) to consist of two fractions with different NMR parameters. The slow fraction of Na+ in these tissues has NMR relaxation times T1 and T2 of 10-15 10-3 sec, which is approximately 4-5 times shorter than for Na+ in aqueous NaCl solution. The slow fraction may represent Na+ dissolved in structured tissue water. The fast fraction of tissue Na+, which is shown to represent approximately 65% of the total tissue Na+ concentration, has T2 less than 1 10-3 sec, which resembles the values of T2 observed for Na+ complexed by synthetic ion-exchange resins. One is drawn to the conclusion that approximately 65% of total Na+ in muscle, brain, and kidney is complexed by tissue macromolecules. PMID:5496905

  17. Frequency characteristics of a nuclear spin maser for the search for the electric dipole moment of 129Xe atom

    NASA Astrophysics Data System (ADS)

    Inoue, T.; Tsuchiya, M.; Furukawa, T.; Hayashi, H.; Nanao, T.; Yoshimi, A.; Uchida, M.; Matsuo, Y.; Asahi, K.

    2011-01-01

    Frequency characteristics of a 129Xe nuclear spin maser was studied, which is under development at Tokyo Institute of Technology for the search for a permanent electric dipole moment in diamagnetic 129Xe atom. Drifts in the solenoid current and cell temperature were found to be the most influential factors on the maser frequency. From correlation coefficient analysis, there seem to exist other origins of frequency fluctuation, such as phase drifts in the maser oscillation. In order to improve the stability of the maser frequency, the intensity of the pumping laser required to fully polarize 129Xe nuclei was evaluated. Construction of a polarization assessment system for 129Xe gas cells and development of a new scheme of current stabilization are also remarked.

  18. Self-diffusion of linear and cyclic alkanes, measured with pulsed-gradient spin-echo nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    von Meerwall, E.; Ozisik, R.; Mattice, W. L.; Pfister, P. M.

    2003-02-01

    Self-diffusion coefficients of linear and cyclic alkanes in melt, in blends with equivalent linear alkanes, and dissolved in linear polyethylene, were measured by pulsed-gradient spin-echo nuclear magnetic resonance at various temperatures. The results indicate the following: (i) at the same carbon number, cyclic alkanes diffuse more slowly than linear alkanes in their respective melts, but linears and cyclics share a similar rapid rate of decrease with increasing carbon number; (ii) in blends of linear and cyclic alkanes at the same carbon number the single average diffusion coefficient observed varies monotonically as a function of composition; and (iii) two distinct diffusion coefficients are observed in the cycloalkane/linear polyethylene blends, with the extrapolated trace cycloalkane diffusion consistent with Rouse behavior. The results are compared with recent numerical simulations and with experiments in other polymer systems, forming a consistent picture of the effects of diffusant mass, molecular shape and flexibility, and the dynamic attributes of the host material.

  19. Spectrally resolved hyperfine interactions between polaron and nuclear spins in organic light emitting diodes: Magneto-electroluminescence studies

    SciTech Connect

    Crooker, S. A.; Kelley, M. R.; Martinez, N. J. D.; Nie, W.; Mohite, A.; Nayyar, I. H.; Tretiak, S.; Smith, D. L.; Liu, F.; Ruden, P. P.

    2014-10-13

    We use spectrally resolved magneto-electroluminescence (EL) measurements to study the energy dependence of hyperfine interactions between polaron and nuclear spins in organic light-emitting diodes. Using layered devices that generate bright exciplex emission, we show that the increase in EL emission intensity I due to small applied magnetic fields of order 100 mT is markedly larger at the high-energy blue end of the EL spectrum (ΔI/I ∼ 11%) than at the low-energy red end (∼4%). Concurrently, the widths of the magneto-EL curves increase monotonically from blue to red, revealing an increasing hyperfine coupling between polarons and nuclei and directly providing insight into the energy-dependent spatial extent and localization of polarons.

  20. 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.; Otsuka, T.; Suzuki, T.

    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.

  1. Properties of mixtures of cholesterol with phosphatidylcholine or with phosphatidylserine studied by (13)C magic angle spinning nuclear magnetic resonance.

    PubMed Central

    Epand, Richard M; Bain, Alex D; Sayer, Brian G; Bach, Diana; Wachtel, Ellen

    2002-01-01

    The behavior of cholesterol is different in mixtures with phosphatidylcholine as compared with phosphatidylserine. In (13)C cross polarization/magic angle spinning nuclear magnetic resonance spectra, resonance peaks of the vinylic carbons of cholesterol are a doublet in samples containing 0.3 or 0.5 mol fraction cholesterol with 1-palmitoyl-2-oleoyl phosphatidylserine (POPS) or in cholesterol monohydrate crystals, but a singlet with mixtures of cholesterol and 1-palmitoyl-2-oleoyl phosphatidylcholine (POPC). At these molar fractions of cholesterol with POPS, resonances of the C-18 of cholesterol appear at the same chemical shifts as in pure cholesterol monohydrate crystals. These resonances do not appear in samples of POPS with 0.2 mol fraction cholesterol or with POPC up to 0.5 mol fraction cholesterol. In addition, there is another resonance from the cholesterol C18 that appears in all of the mixtures of phospholipid and cholesterol but not in pure cholesterol monohydrate crystals. Using direct polarization, the fraction of cholesterol present as crystallites in POPS with 0.5 mol fraction cholesterol is found to be 80%, whereas with the same mol fraction of cholesterol and POPC none of the cholesterol is crystalline. After many hours of incubation, cholesterol monohydrate crystals in POPS undergo a change that results in an increase in the intensity of certain resonances of cholesterol monohydrate in (13)C cross polarization/magic angle spinning nuclear magnetic resonance, indicating a rigidification of the C and D rings of cholesterol but not other regions of the molecule. PMID:12324423

  2. Carbon-13 and tin-119 relaxation studies of some axially symmetrical organotin compounds

    NASA Astrophysics Data System (ADS)

    Chapelle, S.; Granger, P.

    We have studied a variety of axially symmetrical tin compounds by 119Sn and 13C NMR. Tin was observed at two field strengths and, except for Ph 3SnCl, T1 is field independent and governed mainly by spin-rotation. A chemical-shift anisotropy of 136 ppm is observed for 119Sn in Ph 3SnCl. Deverell's relationship provides a good estimate of the values of the spin-rotational constants and the theory of Woessner, Snowden, and Huntress leads to the values of the rotational diffusion constants.

  3. Carbon-13 variations in fluids from the Cerro Prieto geothermal system

    SciTech Connect

    Janik, C.J.; Nehring, N.L.; Huebner, M.A.; Truesdell, A.H.

    1982-08-10

    The carbon isotope compositions of CO/sub 2/ in steam from Cerro Prieto production well have been measured for 1977, 1979, and 1982. Variations in the delta/sup 13/C values are caused by production-related changes in the chemical and physical parameters of the geothermal system. In 1977, most CO/sub 2/ in the reservoir was isotopically light (delta/sup 13/C = -6.4 +/- 0.4). Heavier CO/sub 2/ was produced from wells in the center of the field (M5,M26,M27) due to deposition of isotopically light calcite caused by near-well boiling. In 1979 nearly all well showed relatively heavy CO/sub 2/, probably due to expansion of aquifer boiling and calcite precipitation. In 1982, many wells in the central part of the field were shut in. The amount of drawndown decreased and as temperatures and pressures near the wells increased, the boiling zones collapsed. The CO/sub 2/ in the fluid then exchanged with the precipitated calcite and became isotopically lighter. The sensitivity of carbon isotopes to calcite precipitations caused by aquifer boiling and to reequilibration with this deposited calcite upon decrease of boiling suggests use as an indicator of these aquifer processes. Surficial CO/sub 2/ of thermal origin was collected in 1981. Generally, the carbon-13 contents were close to CO/sub 2/ from production wells except for high-temperature mud pots and fumaroles containing isotopically light CO/sub 2/ derived from near surface alteration of organic matter.

  4. 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

  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. Magic angle spinning nuclear magnetic resonance apparatus and process for high-resolution in situ investigations

    SciTech Connect

    Hu, Jian Zhi; Sears Jr., Jesse A.; Hoyt, David W.; Mehta, Hardeep S.; Peden, Charles H.F.

    2015-11-24

    A continuous-flow (CF) magic angle sample spinning (CF-MAS) NMR rotor and probe are described for investigating reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions in situ. The rotor includes a sample chamber of a flow-through design with a large sample volume that delivers a flow of reactants through a catalyst bed contained within the sample cell allowing in-situ investigations of reactants and products. Flow through the sample chamber improves diffusion of reactants and products through the catalyst. The large volume of the sample chamber enhances sensitivity permitting in situ .sup.13C CF-MAS studies at natural abundance.

  7. 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.

  8. Vibrational motions and nuclear spin relaxation in paramagnetic complexes: Hexaaquonickel(II) as an example

    NASA Astrophysics Data System (ADS)

    Kruk, Danuta; Kowalewski, Jozef

    2002-03-01

    The proton paramagnetic relaxation enhancement (PRE) in an aqueous solution of nickel(II) is described in terms of electron spin relaxation caused by damped vibrational motions of Eg and T2g symmetry. The damped vibrations generate a transient zero-field splitting (ZFS), of variable amplitude and variable principal direction in the molecular frame, and are modeled by the Smoluchowski equation. The parameters of the model are obtained from a combination of two approaches: first, quantum-chemical calculations of the ZFS as a function of the geometry of the coordination shell of the nickel(II) ion and, second, molecular-dynamic simulations generating a trajectory of water positions around the metal. The description of the electron spin dynamics is included in the calculations of the PRE in two ways: Using the traditional Solomon-Bloembergen-Morgan approach and also by means of the more general slow-motion theory. The calculated PRE as a function of the magnetic field, free of any adjustable parameters, is compared with the experimental data. The two methods of calculating the PRE agree with each otherand with the experimental dataat high magnetic field. At low field, the models predict very different PRE, and only the general model is in reasonable agreement with the experiments.

  9. Nuclear magnetic resonance data of CHF3

    NASA Astrophysics Data System (ADS)

    Kalinowski, H.-O.; Kumar, M.; Gupta, V.; Gupta, R.

    This document is part of Part 1 `Aliphatic Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Brnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  10. 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.

  11. Oscillator strengths and radiative decay rates for spin-changing S-P transitions in helium: finite nuclear mass effects

    NASA Astrophysics Data System (ADS)

    Morton, Donald C.; Schulhoff, Eva E.; Drake, G. W. F.

    2015-12-01

    We have calculated the electric dipole (E1) and magnetic quadrupole (M2) oscillator strengths and spontaneous decay rates for 24 spin-changing transitions of atomic helium. We included the effects of the finite nuclear mass and the anomalous magnetic moment of the electron augmented by the recently derived Pachucki term. The specific transitions for 4He are n{ }1{{{S}}}0-{n}\\prime { }3{{{P}}}{1,2} and n{ }3{{{S}}}1-{n}\\prime { }1{{{P}}}1 with n,{n}\\prime ?slant 3 and n?slant 10 for {n}\\prime =n. For the E1 calculations we used the Breit approximation and pseudostate expansions to perform the perturbation sums over intermediate states in both the length and velocity gauge as a check on both numerical accuracy and validity of the transition operators. The corrections for the nuclear mass and the electron anomaly tend to cancel, indicating that if one is included, then so should be the other. The tables give mass- and anomaly-dependent coefficients permitting the easy generation of results for the other isotopes of helium.

  12. Presence de Carbone-13 dans les elements combustibles de type (U,Pu)O 2 irradies en reacteur rapide

    NASA Astrophysics Data System (ADS)

    Kryger, Bernard; Hagemann, Robert

    1982-06-01

    Du carbone-13 produit par la réaction de capture neutronique 168O + 10n → 136C + 42He se forme dans les combustibles de type oxyde irradiés en neutrons rapides. Cette réaction, dont le seuil d'énergie se situe à 2.35 MeV, conduit à la formation d'une quantité de carbone-13 qui peut varier notablement suivant le spectre neutronique du réacteur (entre 20 et 40 × 10 -6g 13C/g (U,Pu)O 2 pour une fluence de 2 × 10 23 n/cm 2). DES mesures effectuées sur le combustible et la gaine par spectrométrie de masse après irradiation montrent qu'une fraction égale ou supérieure à la moitié du carbone-13 produit dans l'oxyde peut être transférée dans la gaine. Un tel comportement nous fait considérer le carbone-13 comme un véritable marqueur du carbone plus généralement contenu dans l'oxyde et, à ce titre, la détection de cet isotope devrait contribuer à élucider tout particulièrement les mécanismes de carburation de la gaine par les combustibles (U,Pu)O 2 des réacteurs surgénérateurs.

  13. Nuclear Spin Relaxation and Water Self-diffusion in Hardening Magnesium Oxychloride Cement

    NASA Astrophysics Data System (ADS)

    Nestle, Nikolaus; Galvosas, Petrik; Zimmermann, Christian; Dakkouri, Marwan; Kärger, Jörg

    2001-08-01

    In this contribution, we report the results of NMR studies of the behaviour of water in a hydrating Sorel cement paste with a composition close to the stoichiometric optimum. Both the transverse spin-relaxation behaviour and water self-diffusion were studied in two separate experiments performed on samples on the basis of the same formulation. While there is a very strong initial decrease in the transverse relaxation time of the water in the paste, the diffusion coefficient is found to decrease mainly at later times of the hydration process where the decrease of the transverse relaxation time has already strongly slowed down. After about 6 h of the hardening process, the signal intensity available for a pulsed gradient diffusometry experiment is not sufficient any more for reliable measurements of the diffusion coefficients

  14. Impact of pairing correlations on the orientation of the nuclear spin

    NASA Astrophysics Data System (ADS)

    Zhao, P. W.; Zhang, S. Q.; Meng, J.

    2015-09-01

    For the first time, the tilted axis cranking covariant density functional theory with pairing correlations has been formulated and implemented in a fully self-consistent and microscopic way to investigate the evolution of the spin axis and the pairing effects in rotating triaxial nuclei. The measured energy spectrum and transition probabilities for the 135Nd yrast band are reproduced well without any ad hoc renormalization factors when pairing effects are taken into account. A transition from collective to chiral rotation has been demonstrated. It is found that pairing correlations introduce additional admixtures in the single-particle orbitals, and, thus, influence the structure of tilted axis rotating nuclei by reducing the magnitude of the proton and neutron angular momenta while merging their direction.

  15. Characterization of heteronuclear decoupling through proton spin dynamics in solid-state nuclear magnetic resonance spectroscopy

    NASA Astrophysics Data System (ADS)

    De Pape, Gal; Elna, Bndicte; Emsley, Lyndon

    2004-08-01

    The work presented here aims at understanding the performance of phase modulated heteronuclear decoupling sequences such as Cosine Modulation or Two Pulse Phase Modulation. To that end we provide an analytical description of the intrinsic behavior of Cosine Modulation decoupling with respect to radio-frequency-inhomogeneity and the proton-proton dipolar coupling network. We discover through a Modulation Frame average Hamiltonian analysis that best decoupling is obtained under conditions where the heteronuclear interactions are removed but notably where homonuclear couplings are recoupled at a homonuclear Rotary Resonance (HORROR) condition in the Modulation Frame. These conclusions are supported by extensive experimental investigations, and notably through the introduction of proton nutation experiments to characterize spin dynamics in solids under decoupling conditions. The theoretical framework presented in this paper allows the prediction of the optimum parameters for a given set of experimental conditions.

  16. 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.

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

    NASA Astrophysics Data System (ADS)

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

    2007-02-01

    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 H1 directly bound to C13. The spin dynamics of this modified BIRD experiment is described using the product-operator formalism, where experimental considerations such as rotor synchronization and the effect of large chemical shielding anisotropies on I and S are discussed. Two experiments are proposed that accommodate large chemical shielding anisotropies on S: (1) by stepping the inversion pulse frequency through the entire S spectral range or (2) by adiabatically inverting the S spins. Both these experiments are shown to successfully select the signal of F19 bound to Xe129 in XeF+ salts, removing the contributions from isotopomers containing non-spin-1/2 Xe isotopes. The feasibility in obtaining isotope-selective F19 spectra of inorganic fluoride compounds is discussed, and further modifications are proposed to expand the application to other chemical systems.

  18. 63,65Cu Nuclear Resonance Study of the Coupled Spin Dimers and Chains Compound Cu2Fe2Ge4O13

    NASA Astrophysics Data System (ADS)

    Kikuchi, Jun; Nagura, Shiro; Murakami, Kazumasa; Masuda, Takatsugu; Redhammer, Gnther J.

    2013-03-01

    Nuclear magnetic resonance (NMR) and nuclear quadrupole resonance (NQR) of Cu have been measured in a coupled spin dimers and chains compound Cu2Fe2Ge4O13. Cu NQR has also been measured in an isostructural material Cu2Sc2Ge4O13 including only spin dimers. Comparison of the temperature dependence of the 63Cu nuclear spin--lattice relaxation rate between the two compounds reveals that the Fe chains in Cu2Fe2Ge4O13 do not change a spin gap energy of the Cu dimers from that in Cu2Sc2Ge4O13, contributing additionally to the relaxation rate at the Cu site. A modestly large internal field of 3.39 T was observed at the Cu site in the antiferromagnetic state of Cu2Fe2 Ge4O13 at 4.2 K, which is partly because of quantum reduction of the ordered moment of a Cu atom. The internal field and the ordered moment of Cu are noncollinear due to large anisotropy of the hyperfine interaction at the Cu site. A model analysis of the internal field based on the fourfold planar coordination of Cu suggests that a 3d hole of the Cu2+ ion is mainly in the d(x2-y2) orbital state.

  19. Study of order and dynamics in liquid crystalline materials by carbon-13 and deuterium NMR spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Jiadi

    This dissertation investigates the phase structures, molecular structures and diffusion motions in some recently discovered liquid crystals using 1D and 2D carbon-13 and deuterium NMR spectroscopy. Two classes of liquid crystals are involved: chiral rod-like liquid crystals and banana mesogens. Our investigations of these new materials were divided into five main sections. The ordering and structures of banana liquid crystals and chiral rod-like mesogens were extracted from solid-state 13C NMR experiments including Separated-Local-Field study based on Lee-Goldberg Cross-Polarization (LGCP-SLF) and temperature dependent chemical shifts. The principal values of CSA tensor were measured using Separation of Undistorted CSA Powder patterns by Effortless Recoupling (SUPER) experiment. Some ID and 2D pulse experiments were performed for the assignment of carbon peaks, such as Cross-Polarization Polarization-Inversion (CPPI), HECTOR and so on. The soliton-like distortion of the helicoidal structure in the chiral smectic C phase (SmC*) of 8BEF5 liquid crystal was observed by the angular dependent DNMR patterns, and quantitatively interpreted based on Landau theory. The distortion was induced by the NMR magnetic field. The phase structure and interlayer diffusion in anticlinic Sm C* phases (Sm C*A , Sm C*Fi1 and Sm C*Fi2 ) of 10B1M7 liquid crystal were measured using angular dependent DNMR lineshapes and echo intensities. This work represents the first study of ferrielectric smectic phases by means of NMR. Measurements of the interlayer diffusion in synclinic and anticlinic SmC* phases (SmC*, Sm C*Fi1 and Sm C*Fi2 ) of 10B1M7 were carried out using 2H NMR exchange experiments. The phase structures of anticlinic SmC* phases were also determined using the same technique. A 'deformed clock model' was found to be appropriate for these phases. Molecular structures and dynamics were investigated in an exotic B 2 phase of a banana liquid crystal Pbis11BB by means of CP-MAS 13C NMR, MAS 2D 13C NMR exchange and LGCP-SLF (with MAS) experiments. These experiments showed that the molecules have asymmetric conformation in the solid state and carry on much slower motions in solid and liquid states compared to banana molecules in the same homologous series.

  20. Cost-effectiveness of the Carbon-13 Urea Breath Test for the Detection of Helicobacter Pylori

    PubMed Central

    Masucci, L; Blackhouse, G; Goeree, R

    2013-01-01

    Objectives This analysis aimed to evaluate the cost-effectiveness of various testing strategies for Helicobacter pylori in patients with uninvestigated dyspepsia and to calculate the budgetary impact of these tests for the province of Ontario. Data Sources Data on the sensitivity and specificity were obtained from the clinical evidence-based analysis. Resource items were obtained from expert opinion, and costs were applied on the basis of published sources as well as expert opinion. Review Methods A decision analytic model was constructed to compare the costs and outcomes (false-positive results, false-negative results, and misdiagnoses avoided) of the carbon-13 (13C) urea breath test (UBT), enzyme-linked immunosorbent assay (ELISA) serology test, and a 2-step strategy of an ELISA serology test and a confirmatory 13C UBT based on the sensitivity and specificity of the tests and prevalence estimates. Results The 2-step strategy is more costly and more effective than the ELISA serology test and results in $210 per misdiagnosis case avoided. The 13C UBT is dominated by the 2-step strategy, i.e., it is more costly and less effective. The budget impact analysis indicates that it will cost $7.9 million more to test a volume of 129,307 patients with the 13C UBT than with ELISA serology, and $4.7 million more to test these patients with the 2-step strategy. Limitations The clinical studies that were pooled varied in the technique used to perform the breath test and in reference standards used to make comparisons with the breath test. However, these parameters were varied in a sensitivity analysis. The economic model was designed to consider intermediate outcomes only (i.e., misdiagnosed cases) and was not a complete model with final patient outcomes (e.g., quality-adjusted life years). Conclusions Results indicate that the 2-step strategy could be economically attractive for the testing of H. pylori. However, testing with the 2-step strategy will cost the Ministry of Health and Long-Term Care $4.7 million more than with the ELISA serology test. PMID:24228083

  1. A geometric representation of nuclear modulation effects: The effects of high electron spin multiplicity on the electron spin echo envelope modulation spectra of Mn2 + complexes of N-ras p21

    NASA Astrophysics Data System (ADS)

    Larsen, Russell G.; Halkides, Christopher J.; Singel, David J.

    1993-05-01

    A theoretical treatment is presented for the analysis of ESEEM spectra of I=1/2 nuclei coupled to an electron spin of high multiplicity, with specific attention to the case of S=5/2. This treatment is shown to account for the observed spectral behavior of 15N and 31P nuclei coupled to Mn2+ in a GDP complex with the protein N-ras p21. The treatment involves the decomposition of the multilevel electron spin system into a set of noninteracting two level systems, an approximation that is valid when the dispersed EPR spectral width is large compared to the microwave excitation bandwidth. The consequent spectral selectivity of the microwave excitation is accounted for, in ESEEM simulations, by attaching a weight to the ESEEM subspectra associated with each EPR transition, and calculating the total ESEEM spectrum as a weighted superposition of the subspectra. The simplest means of estimating the appropriate weight factorsidentifying them with the cw EPR intensity of each transition, as deduced by simulation of the EPR spectraleads to ESEEM simulations that account for the key features of the observed spectra, in particular, features that are peculiar to high multiplicity spin systems. In the studied Mn2+ system, no clear indication of orientation selective effects were found. A simple geometric representation is presented which enables the facile understanding of ESEEM spectra of nuclear spin I=1/2 coupled to an electron spin of high spin multiplicity in orientationally disordered solids. Analytical expressions are derived for the ESEEM frequencies, frequency dispersions and amplitudes. It is shown that in these systems external field variation can lead to an array of spectral line-narrowing and amplitude resonance phenomena analogous to those observed in S=1/2 systems.

  2. Probing the formation and evolution of comets via nuclear spin temperatures of C_2H_6, CH_3OH, CH_4, NH_3, and H_2O

    NASA Astrophysics Data System (ADS)

    Villanueva, G.; Mumma, M.; Bonev, B.; DiSanti, M.; Paganini, L.; Magee-Sauer, K.; Gibb, E.

    2014-07-01

    Comets are true remnants of our primordial Solar System, and provide unique clues to its formation and evolution, including the delivery of organics and water to our planet. A key indicator stored in the molecular structure of the nuclear ices is the spin temperature (T_{spin}), derived from spin-isomeric ratios (R_{spin}, e.g., ortho/para). At the time when cometary ices formed, the prevailing temperature defined the relative abundance of the different spin-isomeric species, and herewith R_{spin} and T_{spin} are normally treated as ''remnant thermometers'' probing the formation environments of cometary molecules. Radiative and collisional transitions between the ortho and para states are strongly forbidden and herewith this indicator is preserved over time. Most of our knowledge of this indicator comes from the measurements of the ortho-para ratios in water and NH_2 (a proxy for ammonia), suggesting a common T_{spin} near 30 K. This information is based on a restricted sample of comets, and the measurements are particularly sensitive to the molecular modeling technique and adopted spectral database. Here, we present new methodologies for extracting spin temperatures from ethane (C_2H_6), methane (CH_4), and methanol (CH_3OH), and advanced new models for ortho/para water (H_2O) and ammonia (NH_3). Our H_2O analysis is based on the most complete fluorescence radiative-transfer model to date, which incorporates 1,200 million transitions including those originating from high-energy levels that are activated in comets via a non-resonant cascade. In a similar fashion, we developed non-resonant fluorescence models for NH_3 and HCN, and quantum-band models for the ?_7 band of C_2H_6 and ?_3 band of CH_3OH. All models respect spin-symmetry non-conversion radiative rules, and make use of a realistic solar spectrum for the computation of fluorescence pumps. We applied these new methods to derive spin-isomeric ratios for H_2O, CH_4, C_2H_6, CH_3OH, and NH_3 from three high- quality cometary datasets: 1) C/2007 W1 (Boattini), 2) C/2001 A2 (LINEAR), and 3) 8P/Tuttle. We compare our results to the measured organic compositions for these comets, and present possible formation and evolution scenarios.

  3. Nuclear spin hyperpolarization of the solvent using signal amplification by reversible exchange (SABRE)

    NASA Astrophysics Data System (ADS)

    Moreno, Karlos X.; Nasr, Khaled; Milne, Mark; Sherry, A. Dean; Goux, Warren J.

    2015-08-01

    Here we report the polarization of the solvent OH protons by SABRE using standard iridium-based catalysts under slightly acidic conditions. Solvent polarization was observed in the presence of a variety of structurally similar N-donor substrates while no solvent enhancement was observed in the absence of substrate or para-hydrogen (p-H2). Solvent polarization was sensitive to the polarizing field and catalyst:substrate ratio in a manner similar to that of substrate protons. SABRE experiments with pyridine-d5 suggest a mechanism where hyperpolarization is transferred from the free substrate to the solvent by chemical exchange while measured hyperpolarization decay times suggest a complimentary mechanism which occurs by direct coordination of the solvent to the catalytic complex. We found the solvent hyperpolarization to decay nearly 3 times more slowly than its characteristic spin-lattice relaxation time suggesting that the hyperpolarized state of the solvent may be sufficiently long lived (?20 s) to hyperpolarize biomolecules having exchangeable protons. This route may offer future opportunities for SABRE to impact metabolic imaging.

  4. The importance of suppressing spin diffusion effects in the accurate determination of the spatial structure of a flexible molecule by nuclear Overhauser effect spectroscopy

    NASA Astrophysics Data System (ADS)

    Khodov, I. A.; Efimov, S. V.; Klochkov, V. V.; Batista de Carvalho, L. A. E.; Kiselev, M. G.

    2016-02-01

    Two-dimensional nuclear Overhauser effect spectroscopy is applied to the elucidation of conformation distribution of small molecules in solution. An essential influence of the nonlinear multistep magnetization transfer (spin diffusion) on the NMR-based analysis of conformers distribution for small druglike molecules in solution was revealed. Therefore, the spin diffusion should be eliminated from the obtained NMR data in order to obtain accurate results. Efficiency of QUIET-NOESY spectroscopy in solving the problem of accurate determination of inter-proton distances in a small molecule was shown in a study of ibuprofen. Although it requires much experimental time, this technique was found to be helpful to solve the spin diffusion problem.

  5. Mesoporous Silica Nanoparticles Loaded with Surfactant: Low Temperature Magic Angle Spinning 13C and 29Si NMR Enhanced by Dynamic Nuclear Polarization

    SciTech Connect

    Lafon, Olivier; Thankamony, Aany S. Lilly; Kokayashi, Takeshi; Carnevale, Diego; Vitzthum, Veronika; Slowing, Igor I.; Kandel, Kapil; Vezin, Herve; Amoureux, Jean-Paul; Bodenhausen, Geoffrey; Pruski, Marek

    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 1H1H 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.

  6. Four-Component Relativistic Density-Functional Theory Calculations of Nuclear Spin-Rotation Constants: Relativistic Effects in p-Block Hydrides.

    PubMed

    Komorovsky, Stanislav; Repisky, Michal; Malkin, Elena; Demissie, Taye B; Ruud, Kenneth

    2015-08-11

    We present an implementation of the nuclear spin-rotation (SR) constants based on the relativistic four-component Dirac-Coulomb Hamiltonian. This formalism has been implemented in the framework of the Hartree-Fock and Kohn-Sham theory, allowing assessment of both pure and hybrid exchange-correlation functionals. In the density-functional theory (DFT) implementation of the response equations, a noncollinear generalized gradient approximation (GGA) has been used. The present approach enforces a restricted kinetic balance condition for the small-component basis at the integral level, leading to very efficient calculations of the property. We apply the methodology to study relativistic effects on the spin-rotation constants by performing calculations on XHn (n = 1-4) for all elements X in the p-block of the periodic table and comparing the effects of relativity on the nuclear SR tensors to that observed for the nuclear magnetic shielding tensors. Correlation effects as described by the density-functional theory are shown to be significant for the spin-rotation constants, whereas the differences between the use of GGA and hybrid density functionals are much smaller. Our calculated relativistic spin-rotation constants at the DFT level of theory are only in fair agreement with available experimental data. It is shown that the scaling of the relativistic effects for the spin-rotation constants (varying between Z(3.8) and Z(4.5)) is as strong as for the chemical shieldings but with a much smaller prefactor. PMID:26574455

  7. 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

  8. 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

  9. 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 ΔT2 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 μg/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

  10. Detection of a Spin-Triplet Superconducting Phase in Oriented Polycrystalline U2PtC2 Samples Using 195Pt Nuclear Magnetic Resonance

    NASA Astrophysics Data System (ADS)

    Mounce, A. M.; Yasuoka, H.; Koutroulakis, G.; Ni, N.; Bauer, E. D.; Ronning, F.; Thompson, J. D.

    2015-03-01

    Nuclear magnetic resonance (NMR) measurements on the 195Pt nucleus in an aligned powder of the moderately heavy-fermion material U2PtC2 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 /T1, in the normal state, exhibits characteristics of ferromagnetic fluctuations, compatible with an enhanced Wilson ratio. In the superconducting state, 1 /T1 follows a power law with temperature without a coherence peak giving additional support that U2PtC2 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.

  11. Spin-polarized /sup 3/He nuclear targets and metastable /sup 4/He atoms by optical pumping with a tunable, Nd:YAP laser

    SciTech Connect

    Bohler, C.L.; Schearer, L.D.; Leduc, M.; Nacher, P.J.; Zachorowski, L.; Milner, R.G.; McKeown, R.D.; Woodward, C.E.

    1988-04-15

    Several Nd:YAP lasers were constructed which could be broadly tuned in the 1083-nm region which includes the helium 2/sup 3/S-2/sup 3/P transition, using a Lyot filter and thin, uncoated etalons within the laser cavity. 1 W of power could be extracted at 1083 nm through a 1% transmitting output coupler. This laser beam was used to optically pump metastable /sup 4/He and /sup 3/He 2/sup 3/S helium atoms in a weak discharge cell, spin polarizing the metastable ensemble. In a /sup 3/He cell the polarization is transferred to the nuclear spin system. A /sup 3/He target cell at 0.3 Torr was polarized to 52% in a few minutes. We describe the application of this system to the design of polarized targets for experiments in nuclear physics.

  12. 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.

  13. Method for accurate measurements of nuclear-spin optical rotation for applications in correlated optical-NMR spectroscopy.

    PubMed

    Savukov, I M; Chen, H-Y; Karaulanov, T; Hilty, C

    2013-07-01

    The nuclear-spin optical rotation (NSOR) effect recently attracted much attention due to potential applications in combined optical-NMR spectroscopy and imaging. Currently, the main problem with applications of NSOR is low SNR and accuracy of measurements. In this work we demonstrate a new method for data acquisition and analysis based on a low-power laser and an emphasis on software based processing. This method significantly reduces cost and is suitable for application in most NMR spectroscopy laboratories for exploration of the NSOR effect. Despite the use of low laser power, SNR can be substantially improved with fairly simple strategies including the use of short wavelength and a multi-pass optical cell with in-flow pre-polarization in a 7 T magnet. Under these conditions, we observed that NSOR signal can be detected in less than 1 min and discuss strategies for further improvement of signal. With higher SNR than previously reported, NSOR constants can be extracted with improved accuracy. On the example of water, we obtained measurements at a level of accuracy of 5%. We include a detailed theoretical analysis of the geometrical factors of the experiment, which is required for accurate quantification of NSOR. This discussion is particularly important for relatively short detection cells, which will be necessary to use in spectroscopy or imaging applications that impose geometrical constraints. PMID:23685716

  14. 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.; Crabtree, K. N.; McCall, B. J.; Gaertner, S.; Schlemmer, S.

    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.

  15. 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.; McCall, Benjamin J.

    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.

  16. The radiation-induced oxidation and reduction of guanine: Electron spin resonance-electron nuclear double resonance studies of irradiated guanosine cyclic monophosphate

    NASA Astrophysics Data System (ADS)

    Kim, Heasook; Budzinski, Edwin E.; Box, Harold 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.

  17. 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.; McCall, Benjamin J.

    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}.

  18. Nuclear properties of the exotic high-spin isomer {sup 178m2}Hf

    SciTech Connect

    Krieg, M.; Boos, N.; Le Blanc, F.; Pinard, J.; Huber, G.; Lunney, M. D.; Le Du, D.; Meunier, R.; Hussonnois, M.; Constantinescu, O.; Kim, J. B.; Briancon, Ch.; Crawford, J. E.; Duong, H. T.; Gangrski, Y. P.; Kuehl, T.; Markov, B. N.; Oganessian, Yu. Ts.; Quentin, P.; Roussiere, B.

    1995-04-01

    The complete hyperfine spectrum in the optical transition 5d{sup 2}6s{sup 2} 3{sup P}2{yields}5d6s{sup 2}6p {sup 1}P1 of {sup 178m2}Hf was recorded by collinear laser spectroscopy using nanogram amounts of samples. The quadrupole moment and isomer shift were determined for the first time as well as a precise value and the sign of the magnetic dipole moment. The change in nuclear mean-square charge radius between the isomeric state {sup 178m2}Hf and the ground state {sup 178g}Hf was evaluated as {delta}{sup 178,178m2}=-0.059(9) fm{sup 2}. From the hyperfine A- and B-factors the magnetic moment {gamma}I{sup 178m2}=+8.16(4){mu}N and the spectroscopic quadrupole moment Q{sup 178m2}s=6.00(7) b were extracted. In an additional experiment using a RIS scheme we recorded the A- and B-factors and the isotope shift of the 5d{sup 2}6s{sup 23} F3{yields}5d{sup 2}6s6p {sup 3}G4 and the 5d{sup d}6s{sup 2} {sup 3}P0{yields}5d{sup 2}6s6p {sup 3}D1 transition.

  19. Elucidation of intermediate (mobile) and slow (solidlike) protein motions in bovine lens homogenates by carbon-13 NMR spectroscopy

    SciTech Connect

    Morgan, C.F.; Schleich, T.; Caines, G.H.; Farnsworth, P.N. )

    1989-06-13

    The motional dynamics of lens cytoplasmic proteins present in calf lens homogenates were investigated by two {sup 13}C nuclear magnetic resonance (NMR) techniques sensitive to molecular motion to further define the organizational differences between the cortex and nucleus. For the study of intermediate (mobile) protein rotational reorientation motion time scales (rotational correlation time ({tau}{sub 0}) range of 1-500 ns), the authors employed {sup 13}C off-resonance rotating frame spin-lattice relaxation, whereas for the study of slow (solidlike) motions ({tau}{sub 0} {ge} 10 {mu}s) they used the solid-state NMR techniques of dipolar decoupling and cross-polarization. The frequency dependence of the peptide bond carbonyl off-resonance rotating frame spectral intensity ratio of the lens proteins present in native calf nuclear homogenate at 35{degree}C indicates the presence of a polydisperse mobile protein fraction with a {tau}{sub 0,eff} (mean) value of 57 ns. Lowering the temperature to 1{degree}C, a temperature which produces the cold cataract, results in an overall decrease in {tau}{sub 0,eff} to 43 ns, suggesting a selective removal of {beta}{sub H}-, LM-, and possibly {gamma}{sub s}-crystallins from the mobile lens protein population. The presence of solidlike or motionally restricted protein species was established by dipolar decoupling and cross-polarization. Comparison of proton dipolar-decoupled and nondecoupled {sup 13}C NMR spectra of native cortical homogenate at 20{degree}C indicates the absence of significant contributions from slowly tumbling, motionally restricted species. These studies establish the presence of both mobile and solidlike protein phases in calf lens nuclear homogenate, whereas for the native cortical homogenate, within the detection limits of NMR, the protein phase is mobile, except at low temperature where a small fraction of solidlike protein phase is present.

  20. Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe1xCox)2As2 studied by As75 nuclear magnetic resonance and anisotropic resistivity

    DOE PAGESBeta

    Cui, J.; Roy, B.; Tanatar, M. A.; Ran, S.; Bud'ko, S. L.; Prozorov, R.; Canfield, P. C.; Furukawa, Y.

    2015-11-06

    We report 75As nuclear magnetic resonance (NMR) measurements of single-crystalline Ca(Fe1xCox)2As2 (x=0.023, 0.028, 0.033, and 0.059) annealed at 350C for 7 days. From the observation of a characteristic shape of 75As NMR spectra in the stripe-type antiferromagnetic (AFM) state, as in the case of x=0 (TN=170 K), clear evidence for the commensurate AFM phase transition with the concomitant structural phase transition is observed in x=0.023 (TN=106 K) and x=0.028 (TN=53 K). Through the temperature dependence of the Knight shifts and the nuclear spin lattice relaxation rates (1/T1), although stripe-type AFM spin fluctuations are realized in the paramagnetic state as inmorethe case of other iron pnictide superconductors, we found a gradual decrease of the AFM spin fluctuations below a crossover temperature T* that was nearly independent of Co-substitution concentration, and it is attributed to a pseudogaplike behavior in the spin excitation spectra of these systems. The T* feature finds correlation with features in the temperature-dependent interplane resistivity, ?c(T), but not with the in-plane resistivity ?a(T). The temperature evolution of anisotropic stripe-type AFM spin fluctuations is tracked in the paramagnetic and pseudogap phases by the 1/T1 data measured under magnetic fields parallel and perpendicular to the c axis. As a result, based on our NMR data, we have added a pseudogaplike phase to the magnetic and electronic phase diagram of Ca(Fe1xCox)2As2.less

  1. Antiferromagnetic spin correlations and pseudogaplike behavior in Ca (Fe1-xCox) 2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity

    NASA Astrophysics Data System (ADS)

    Cui, J.; Roy, B.; Tanatar, M. A.; Ran, S.; Bud'ko, S. L.; Prozorov, R.; Canfield, P. C.; Furukawa, Y.

    2015-11-01

    We report 75As nuclear magnetic resonance (NMR) measurements of single-crystalline Ca (Fe1-xCox) 2As2 (x =0.023 , 0.028, 0.033, and 0.059) annealed at 350 C for 7 days. From the observation of a characteristic shape of 75As NMR spectra in the stripe-type antiferromagnetic (AFM) state, as in the case of x =0 (TN=170 K), clear evidence for the commensurate AFM phase transition with the concomitant structural phase transition is observed in x =0.023 (TN=106 K) and x =0.028 (TN=53 K). Through the temperature dependence of the Knight shifts and the nuclear spin lattice relaxation rates (1 /T1 ), although stripe-type AFM spin fluctuations are realized in the paramagnetic state as in the case of other iron pnictide superconductors, we found a gradual decrease of the AFM spin fluctuations below a crossover temperature T* that was nearly independent of Co-substitution concentration, and it is attributed to a pseudogaplike behavior in the spin excitation spectra of these systems. The T* feature finds correlation with features in the temperature-dependent interplane resistivity, ?c(T ) , but not with the in-plane resistivity ?a(T ) . The temperature evolution of anisotropic stripe-type AFM spin fluctuations is tracked in the paramagnetic and pseudogap phases by the 1 /T1 data measured under magnetic fields parallel and perpendicular to the c axis. Based on our NMR data, we have added a pseudogaplike phase to the magnetic and electronic phase diagram of Ca (Fe1-xCox) 2As2 .

  2. Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe1xCox)2As2 studied by ??As nuclear magnetic resonance and anisotropic resistivity

    DOE PAGESBeta

    Cui, J.; Roy, B.; Tanatar, M. A.; Ran, S.; Bud'ko, S. L.; Prozorov, R.; Canfield, P. C.; Furukawa, Y.

    2015-11-06

    We report 75As nuclear magnetic resonance (NMR) measurements of single-crystalline Ca(Fe1xCox)2As2 (x=0.023, 0.028, 0.033, and 0.059) annealed at 350C for 7 days. From the observation of a characteristic shape of 75As NMR spectra in the stripe-type antiferromagnetic (AFM) state, as in the case of x=0 (TN=170 K), clear evidence for the commensurate AFM phase transition with the concomitant structural phase transition is observed in x=0.023 (TN=106 K) and x=0.028 (TN=53 K). Through the temperature dependence of the Knight shifts and the nuclear spin lattice relaxation rates (1/T1), although stripe-type AFM spin fluctuations are realized in the paramagnetic state as inmorethe case of other iron pnictide superconductors, we found a gradual decrease of the AFM spin fluctuations below a crossover temperature T* that was nearly independent of Co-substitution concentration, and it is attributed to a pseudogaplike behavior in the spin excitation spectra of these systems. The T* feature finds correlation with features in the temperature-dependent interplane resistivity, ?c(T), but not with the in-plane resistivity ?a(T). The temperature evolution of anisotropic stripe-type AFM spin fluctuations is tracked in the paramagnetic and pseudogap phases by the 1/T1 data measured under magnetic fields parallel and perpendicular to the c axis. As a result, based on our NMR data, we have added a pseudogaplike phase to the magnetic and electronic phase diagram of Ca(Fe1xCox)2As2.less

  3. Antiferromagnetic spin correlations and pseudogaplike behavior in Ca(Fe1-xCox)2As2 studied by 75As nuclear magnetic resonance and anisotropic resistivity

    DOE PAGESBeta

    Cui, J.; Roy, B.; Tanatar, M. A.; Ran, S.; Bud'ko, S. L.; Prozorov, R.; Canfield, P. C.; Furukawa, Y.

    2015-11-06

    We report 75As nuclear magnetic resonance (NMR) measurements of single-crystalline Ca(Fe1–xCox)2As2 (x=0.023, 0.028, 0.033, and 0.059) annealed at 350°C for 7 days. From the observation of a characteristic shape of 75As NMR spectra in the stripe-type antiferromagnetic (AFM) state, as in the case of x=0 (TN=170 K), clear evidence for the commensurate AFM phase transition with the concomitant structural phase transition is observed in x=0.023 (TN=106 K) and x=0.028 (TN=53 K). Through the temperature dependence of the Knight shifts and the nuclear spin lattice relaxation rates (1/T1), although stripe-type AFM spin fluctuations are realized in the paramagnetic state as inmore » the case of other iron pnictide superconductors, we found a gradual decrease of the AFM spin fluctuations below a crossover temperature T* that was nearly independent of Co-substitution concentration, and it is attributed to a pseudogaplike behavior in the spin excitation spectra of these systems. The T* feature finds correlation with features in the temperature-dependent interplane resistivity, ρc(T), but not with the in-plane resistivity ρa(T). The temperature evolution of anisotropic stripe-type AFM spin fluctuations is tracked in the paramagnetic and pseudogap phases by the 1/T1 data measured under magnetic fields parallel and perpendicular to the c axis. As a result, based on our NMR data, we have added a pseudogaplike phase to the magnetic and electronic phase diagram of Ca(Fe1–xCox)2As2.« less

  4. Cadmium 113 and carbon 13 NMR studies of ligand binding to pig heart NADP-dependent isocitrate dehydrogenase

    SciTech Connect

    Ehrlich, R.S.; Colman, R.F.

    1986-05-01

    Isocitrate dehydrogenase catalyzes the conversion of isocitrate to ..cap alpha..-ketoglutarate. The reaction requires a divalent metal. NMR studies using cadmium 113 reveal a resonance in the enzyme-metal-isocitrate complex at 8 ppm relative to Cd(ClO/sub 4/)/sub 2/; whereas, in the absence of enzyme, the Cd-isocitrate complex has a resonance at approx.18 ppm. The resonance of enzyme-bound cadmium is typical of cadmium in a complex containing 6 oxygen ligands. Carbon 13 studies were done using specific enrichments at the 1, 2, or 5 positions of ..cap alpha..-ketoglutarate and isocitrate, synthesized by enzymatic conversion from glutamate. The carbon 13 resonances of the 1 and 5 carboxyl of ..cap alpha..-ketoglutarate are identical in free and enzyme-bound forms over the pH range 5.5-7.5, implying the absence of alterations in geometry of the enzyme-bound form. The 2-carbonyl resonance could not be located in the bound form, suggesting either significant perturbation or immobilization of this group. While the resonances of the carboxyls of free isocitrate shift over the pH range 5-8 reflecting a pK of 5.37, the positions of enzyme-bound resonances remain constant over this pH range. This indicates that isocitrate remains ionized in the enzyme-bound form.

  5. Nuclear magnetic resonance data of C6H14NCl

    NASA Astrophysics Data System (ADS)

    Kalinowski, H.-O.; Kumar, M.; Gupta, V.; Gupta, R.

    This document is part of Part 1 `Aliphatic Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Brnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  6. Paramagnetic carbon-13 shifts induced by the free radical tempo. 2. Nitrogen heterocycles

    SciTech Connect

    Qui, Z.W.; Grant, D.M.; Pugmire, R.J.

    1984-02-08

    With use of the free radical Tempo as a shift and relaxation reagent, both paramagnetic shifts and spin-lattice relaxation rates of nitrogen heterocycles are reported. Paramagnetic shifts of these compounds are larger than the corresponding shifts of the aromatic hydrocarbons, indicating a stronger interaction between nitrogen heterocyclic compounds and Tempo. Paramagnetic shifts increase with the number of nitrogen atoms per molecule. For pyridine type compounds, both shift and relaxation data show that the stronger interaction is not at the adjacent positions to the nitrogen atoms. It would appear in these heterocyclic complexes with Tempo that the nitrogen atoms tend to orient away from the N-O group in Tempo. In contrast, imidazole and indole exhibit a much stronger interaction with the Tempo due to hydrogen bond formation, and the positions near the N-H group exhibit larger paramagnetic shifts and relaxation rates. An approximate static model involving an indole-Tempo, hydrogen-bond complex accounts for the relaxation data from which both an equilibrium constant of complexation and a hydrogen-bond distance in the indole-Tempo complex could be estimated.

  7. Indole alkaloids of Rauwolfia reflexa. Carbon-13 nuclear magnetic resonance structural analysis of the bis(indole) alkaloid flexicorine

    SciTech Connect

    Chatterjee, A.; 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.

  8. 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...

  9. 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...

  10. 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.

  11. Unusual spin fluctuations and magnetic frustration in olivine and non-olivine LiCoPO4 detected by P31 and Li7 nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Baek, S.-H.; Klingeler, R.; Neef, C.; Koo, C.; Bchner, B.; Grafe, H.-J.

    2014-04-01

    We report P31 and Li7 nuclear magnetic resonance (NMR) studies in new non-olivine LiZnPO4-type LiCoPO4tetra microcrystals, where the Co2+ ions are tetrahedrally coordinated. Olivine LiCoPO4, which was directly transformed from LiCoPO4tetra by an annealing process, was also studied and compared. The uniform bulk magnetic susceptibility and the P31 Knight shift obey the Curie-Weiss law for both materials with a high spin Co2+ (3d7, S =3/2), but the Weiss temperature ? and the effective magnetic moment ?eff are considerably smaller in LiCoPO4tetra. The spin-lattice relaxation rate T1-1 reveals a quite different nature of the spin dynamics in the paramagnetic state of both materials. Our NMR results imply that strong geometrical spin frustration occurs in tetrahedrally coordinated LiCoPO4, which may lead to the incommensurate magnetic ordering.

  12. Slow Magic Angle Sample Spinning: A Non- or Minimally Invasive Method for High- Resolution 1H Nuclear Magnetic Resonance (NMR) Metabolic Profiling

    SciTech Connect

    Hu, Jian Z.

    2011-05-01

    High resolution 1H magic angle spinning nuclear magnetic resonance (NMR), using a sample spinning rate of several kHz or more (i.e., high resolution-magic angle spinning (hr-MAS)), is a well established method for metabolic profiling in intact tissues without the need for sample extraction. The only shortcoming with hr-MAS is that it is invasive and is thus unusable for non-destructive detections. Recently, a method called slow-MAS, using the concept of two dimensional NMR spectroscopy, has emerged as an alternative method for non- or minimal invasive metabolomics in intact tissues, including live animals, due to the slow or ultra-slow-sample spinning used. Although slow-MAS is a powerful method, its applications are hindered by experimental challenges. Correctly designing the experiment and choosing the appropriate slow-MAS method both require a fundamental understanding of the operation principles, in particular the details of line narrowing due to the presence of molecular diffusion. However, these fundamental principles have not yet been fully disclosed in previous publications. The goal of this chapter is to provide an in depth evaluation of the principles associated with slow-MAS techniques by emphasizing the challenges associated with a phantom sample consisting of glass beads and H2O, where an unusually large magnetic susceptibility field gradient is obtained.

  13. Anomalous enrichment of {sup 17}O and {sup 13}C in photodissociation products of CO{sub 2}: Possible role of nuclear spin

    SciTech Connect

    Mahata, Sasadhar; Bhattacharya, S. K.

    2009-06-21

    Oxygen and carbon isotope fractionation associated with products (CO and O{sub 2}) of gas phase photodissociation of CO{sub 2} have been studied using photons from Hg lamp (184.9 nm) and Kr lamp (123.6 and 116.5 nm). In dissociation by Hg lamp photons both CO and O{sub 2} are enriched in {sup 17}O by about 81 per mille compared to the estimate based on a kinetic model. Additionally, CO is enriched in {sup 13}C by about 37 per mille relative to the model composition. In contrast, in dissociation by higher energy Kr lamp photons no such anomaly was found in O{sub 2}. The observed isotopic enrichments in case of Hg lamp dissociation are proposed to be due to a hyperfine interaction between nuclear spin and electron spins or orbital motion causing enhanced dissociation of isotopologues of CO{sub 2} containing {sup 17}O and {sup 13}C. The {sup 17}O enrichment is higher than that of {sup 13}C by a factor of 2.2{+-}0.2 which can be explained by the known magnetic moment ratio of {sup 17}O and {sup 13}C due to differing nuclear spins and g-factors. These results have potential implications in studies of the planetary atmospheres.

  14. Asynchronous MASSLF spectroscopy: A convenient method for assigning solid-state carbon-13 CPMAS spectra

    SciTech Connect

    Webb, G.G.; Zilm, K.W. )

    1989-03-29

    A two-dimensional solid-state NMR technique is presented which permits assignment of {sup 13}C CPMAS spectra on the basis of the number of protons bonded to a carbon center. The method is similar to several other methods that have become popular for accurately determining C-H or N-H bond distances in solids and for following molecular motions in polymers. These techniques, referred to collectively as MASSLF spectroscopy, rely on the use of MAS NMR to resolve dipolar coupled patterns that would normally overlap in static one-dimensional spectra. The dipolar coupled patterns generated by these techniques are sufficiently sensitive that small variations in C-H distances in organic solids can be accurately measured. The patterns are, however, much more sensitive to the number of protons directly bonded to the carbon center. Under conditions of fast magic angle spinning, methylenes typically exhibit twice the number of sidebands as methines, and rapidly rotating methyl groups and nonprotonated carbons usually exhibit only one set of sidebands. The method presented here determines the number of methylenes, methines, and methyl plus nonprotonated carbons contributing to a resonance by taking advantage of the fact that the dipolar patterns have characteristic and predictable relative sideband intensities. A new MASSLF pulse sequence is used in this work that differs from previous sequences by not requiring synchronization with the MAS rotation. In addition the sequence conveniently allows for a much wider bandwidth in the dipolar dimension and produces the effect of quadrature detection in this frequency domain without the need for multiple data sets.

  15. Nuclear-spin-lattice relaxation-rate measurements in YBa[sub 2]Cu[sub 3]O[sub 7

    SciTech Connect

    Martindale, J.A.; Barrett, S.E.; Durand, D.J.; O'Hara, K.E.; Slichter, C.P.; Lee, W.C.; Ginsberg, D.M. )

    1994-11-01

    Experimental details are given for NMR and NQR measurements of nuclear-spin-lattice relaxation rates for the planar copper and oxygen sites in YBa[sub 2]Cu[sub 3]O[sub 7]. Enrichment of samples with [sup 17]O, alignment of powder samples, elimination of artifacts in relaxation-rate measurements, and the unusual aspects of weak magnetic-field experiments used to overcome an observed magnetic-field dependence in the rates are described. The role of fluxoids in the magnetic-field dependence of the relaxation rates is discussed. The relaxation rate data are shown to be inconsistent with a spin-singlet, orbital [ital s]-wave pairing state with an isotropic energy gap.

  16. Conformation of methyl beta-lactoside bound to the ricin B-chain: Interpretation of transferred nuclear Overhauser effects facilitated by spin simulation and selective deuteration

    SciTech Connect

    Bevilacqua, V.L.; Thomson, D.S.; Prestegard, J.H. )

    1990-06-12

    Spin simulation and selective deuteration have been used to aid in the interpretation of 1D transferred nuclear Overhauser effect (TRNOE) NMR experiments on ricin B-chain/ligand systems. Application of these methods has revealed a change in the conformation of deuterated methyl beta-lactoside upon binding to the ricin B-chain which results in a slight change in glycosidic torsional angels which appear to dominate in the solution conformation. The combination of simulation and experiment also shows an important sensitivity of TRNOE magnitudes to dissociation rate constants and available spin-diffusion pathways for the ricin B-chain/ligand systems under study. The sensitivity to dissociation rates allows determination of rate constants for methyl beta-lactoside and methyl beta-galactoside of 50 and 300 s-1, respectively.

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

    NASA Astrophysics Data System (ADS)

    Miranowicz, Adam; Ã-zdemir, Şahin K.; Bajer, Jiří; Yusa, Go; Imoto, Nobuyuki; Hirayama, Yoshiro; Nori, Franco

    2015-08-01

    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, 1001 (2005), 10.1038/nature03456]. These methods are based on an unconventional approach to NMR, where the longitudinal magnetization Mz is directly measured. This is in contrast to the standard NMR experiments and tomographic methods, where the transverse magnetization Mx y is detected. The robustness against errors in the measured data is analyzed by using the condition number based on the spectral norm. We propose several methods with optimized sets of rotations yielding the highest robustness against errors, as described by the condition number equal to 1, assuming an ideal experimental detection. This robustness is only slightly deteriorated, as given by the condition number equal to 1.05, for a more realistic "noisy" Mz detection based on the standard cyclically ordered phase sequence (CYCLOPS) method.

  18. Heat bath algorithmic cooling using electron-nuclear spin ensemble in the solid state: characterization of the open quantum system control

    NASA Astrophysics Data System (ADS)

    Park, Kyungdeock; Darabad, Robabeh; Feng, Guanru; Labruyere, Stephane; Baugh, Jonathan; Laflamme, Raymond

    2015-03-01

    The ability to perform multiple rounds of Quantum Error Correction (QEC) is an essential task for scalable quantum information processing, but experimental realizations of it are still in their infancy. Key requirements for QEC are high control fidelity and the ability to extract entropy from ancilla qubits. Nuclear Magnetic Resonance (NMR) quantum processors have demonstrated high control fidelity with up to 12 qubits. A remaining challenge is to prepare nearly pure ancilla qubits to enable QEC. Heat Bath Algorithmic Cooling (HBAC) is an efficient tool for extracting entropy from qubits that interact with a heat bath, allowing cooling below the bath temperature. For implementing HBAC with spins, a hyperfine coupled electron-nuclear system in a single crystal is more advantageous than conventional NMR systems since the electron, with higher polarization and faster relaxation, can act as a heat bath. We characterize 3 and 5 qubit spin systems in gamma-irradiated malonic acid and present simulation and experimental results of HBAC to benchmark our quantum control. Two control schemes are compared: electron nuclear double resonance and indirect control of nuclei via the anisotropic hyperfine interaction.

  19. Nuclear magnetic relaxation by the dipolar EMOR mechanism: General theory with applications to two-spin systems.

    PubMed

    Chang, Zhiwei; Halle, Bertil

    2016-02-28

    In aqueous systems with immobilized macromolecules, including biological tissue, the longitudinal spin relaxation of water protons is primarily induced by exchange-mediated orientational randomization (EMOR) of intra- and intermolecular magnetic dipole-dipole couplings. We have embarked on a systematic program to develop, from the stochastic Liouville equation, a general and rigorous theory that can describe relaxation by the dipolar EMOR mechanism over the full range of exchange rates, dipole coupling strengths, and Larmor frequencies. Here, we present a general theoretical framework applicable to spin systems of arbitrary size with symmetric or asymmetric exchange. So far, the dipolar EMOR theory is only available for a two-spin system with symmetric exchange. Asymmetric exchange, when the spin system is fragmented by the exchange, introduces new and unexpected phenomena. Notably, the anisotropic dipole couplings of non-exchanging spins break the axial symmetry in spin Liouville space, thereby opening up new relaxation channels in the locally anisotropic sites, including longitudinal-transverse cross relaxation. Such cross-mode relaxation operates only at low fields; at higher fields it becomes nonsecular, leading to an unusual inverted relaxation dispersion that splits the extreme-narrowing regime into two sub-regimes. The general dipolar EMOR theory is illustrated here by a detailed analysis of the asymmetric two-spin case, for which we present relaxation dispersion profiles over a wide range of conditions as well as analytical results for integral relaxation rates and time-dependent spin modes in the zero-field and motional-narrowing regimes. The general theoretical framework presented here will enable a quantitative analysis of frequency-dependent water-proton longitudinal relaxation in model systems with immobilized macromolecules and, ultimately, will provide a rigorous link between relaxation-based magnetic resonance image contrast and molecular parameters. PMID:26931695

  20. Nuclear magnetic relaxation by the dipolar EMOR mechanism: General theory with applications to two-spin systems

    NASA Astrophysics Data System (ADS)

    Chang, Zhiwei; Halle, Bertil

    2016-02-01

    In aqueous systems with immobilized macromolecules, including biological tissue, the longitudinal spin relaxation of water protons is primarily induced by exchange-mediated orientational randomization (EMOR) of intra- and intermolecular magnetic dipole-dipole couplings. We have embarked on a systematic program to develop, from the stochastic Liouville equation, a general and rigorous theory that can describe relaxation by the dipolar EMOR mechanism over the full range of exchange rates, dipole coupling strengths, and Larmor frequencies. Here, we present a general theoretical framework applicable to spin systems of arbitrary size with symmetric or asymmetric exchange. So far, the dipolar EMOR theory is only available for a two-spin system with symmetric exchange. Asymmetric exchange, when the spin system is fragmented by the exchange, introduces new and unexpected phenomena. Notably, the anisotropic dipole couplings of non-exchanging spins break the axial symmetry in spin Liouville space, thereby opening up new relaxation channels in the locally anisotropic sites, including longitudinal-transverse cross relaxation. Such cross-mode relaxation operates only at low fields; at higher fields it becomes nonsecular, leading to an unusual inverted relaxation dispersion that splits the extreme-narrowing regime into two sub-regimes. The general dipolar EMOR theory is illustrated here by a detailed analysis of the asymmetric two-spin case, for which we present relaxation dispersion profiles over a wide range of conditions as well as analytical results for integral relaxation rates and time-dependent spin modes in the zero-field and motional-narrowing regimes. The general theoretical framework presented here will enable a quantitative analysis of frequency-dependent water-proton longitudinal relaxation in model systems with immobilized macromolecules and, ultimately, will provide a rigorous link between relaxation-based magnetic resonance image contrast and molecular parameters.

  1. 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...

  2. Enantiodiscrimination and extraction of short and long range homo- and hetero-nuclear residual dipolar couplings by a spin selective correlation experiment

    NASA Astrophysics Data System (ADS)

    Nath, Nilamoni; Suryaprakash, N.

    2010-08-01

    A two dimensional correlation experiment for the measurement of short and long range homo- and hetero- nuclear residual dipolar couplings (RDCs) from the broad and featureless proton NMR spectra including 13C satellites is proposed. The method employs a single natural abundant 13C spin as a spy nucleus to probe all the coupled protons and permits the determination of RDCs of negligible strengths. The technique has been demonstrated for the study of organic chiral molecules aligned in chiral liquid crystal, where additional challenge is to unravel the overlapped spectrum of enantiomers. The significant advantage of the method is demonstrated in better chiral discrimination using homonuclear RDCs as additional parameters.

  3. Carbon-13 NMR studies and purification of gluconate pathway enzymes from Schizosaccharomyces pombe.

    PubMed

    Tsai, C S; Ye, H G; Shi, J L

    1995-01-10

    Evidence is presented to show that D-glucose in Schizosaccharomyces pombe can be metabolized via a new alternative route (gluconate pathway) in addition to the regular D-glucose 6-phosphate route. This gluconate pathway consists of two steps: oxidation of D-glucose to D-gluconate by NADP(+)-dependent glucose dehydrogenase and phosphorylation of D-gluconate to 6-phosphogluconate by gluconate kinase. The formation of D-gluconate and 6-phosphogluconate from D-glucose was monitored by 13C nuclear magnetic resonance spectroscopy using D-[1-13C]glucose and D-[U-13C]glucose. The operation of the gluconate pathway was further substantiated by the purification of its two member enzymes, glucose dehydrogenase and gluconate kinase, from the cell-free extract of the fission yeast. Glucose dehydrogenase has been purified (580-fold) to homogeneity by the combined procedures of ammonium sulfate fractionation, Sephadex gel filtration, cation-exchange chromatography, matrex gel chromatography, and agarose-NADP+ affinity chromatography. The purified enzyme is monomeric with a relative molecular weight of 6.65 x 10(4) Da. Gluconate kinase has been purified (410-fold) to near homogeneity by a combination of chromatographic procedures using Bio-gels, matrex gel, and agarose gels. The purified enzyme is monomeric with a relative molecular weight of 2.4 x 10(4) Da. The gluconate pathway presented here provides an alternative route for the D-glucose metabolism in Sch. pombe. Meanwhile, this paper documents another metabolic difference between the fission and budding yeasts. PMID:7840611

  4. Absolute NMR shielding scales and nuclear spin-rotation constants in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br and (127)I).

    PubMed

    Demissie, Taye B; Jaszuński, Michał; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-28

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in (175)LuX and (197)AuX (X = (19)F, (35)Cl, (79)Br, (127)I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides. PMID:26520517

  5. Absolute NMR shielding scales and nuclear spin-rotation constants in 175LuX and 197AuX (X = 19F, 35Cl, 79Br and 127I)

    NASA Astrophysics Data System (ADS)

    Demissie, Taye B.; Jaszu?ski, Micha?; Komorovsky, Stanislav; Repisky, Michal; Ruud, Kenneth

    2015-10-01

    We present nuclear spin-rotation constants, absolute nuclear magnetic resonance (NMR) shielding constants, and shielding spans of all the nuclei in 175LuX and 197AuX (X = 19F, 35Cl, 79Br, 127I), calculated using coupled-cluster singles-and-doubles with a perturbative triples (CCSD(T)) correction theory, four-component relativistic density functional theory (relativistic DFT), and non-relativistic DFT. The total nuclear spin-rotation constants determined by adding the relativistic corrections obtained from DFT calculations to the CCSD(T) values are in general in agreement with available experimental data, indicating that the computational approach followed in this study allows us to predict reliable results for the unknown spin-rotation constants in these molecules. The total NMR absolute shielding constants are determined for all the nuclei following the same approach as that applied for the nuclear spin-rotation constants. In most of the molecules, relativistic effects significantly change the computed shielding constants, demonstrating that straightforward application of the non-relativistic formula relating the electronic contribution to the nuclear spin-rotation constants and the paramagnetic contribution to the shielding constants does not yield correct results. We also analyze the origin of the unusually large absolute shielding constant and its relativistic correction of gold in AuF compared to the other gold monohalides.

  6. Nuclear and electron spin relaxation in paramagnetic complexes in solution: Effects of the quantum nature of molecular vibrations

    NASA Astrophysics Data System (ADS)

    Kruk, Danuta; Kowalewski, Jozef; Westlund, Per-Olof

    2004-08-01

    A model of the paramagnetic relaxation enhancement is developed in terms of electron-spin relaxation caused by the zero-field splitting (ZFS) fluctuating in time due to a coupling between the electron-spin variables and quantum vibrations. The ZFS interaction provides a coupling between the electron-spin variables and vibrational degrees of freedom, and is represented as a Taylor series expansion in a set of vibrational modes (normal coordinates). A two-level harmonic oscillator subsystem is assumed, and the electron-spin relaxation associated with T2V and T1V vibrational relaxation is considered. The description of vibrationally induced electron-spin dynamics is incorporated into the calculations of the paramagnetic relaxation enhancement by the Solomon-Bloembergen-Morgan approach as well as in the framework of the general slow-motion theory. The theoretical predictions are compared with the experimental paramagnetic relaxation enhancement values for the Ni(H2O)62+ complex in aqueous solution. The parameters required by the model are obtained from quantum chemical and molecular dynamics studies. Comparison is made between the current model and its recently published classical counterpart.

  7. Effects of strain and quantum confinement in optically pumped nuclear magnetic resonance in GaAs: Interpretation guided by spin-dependent band structure calculations

    DOE PAGESBeta

    Wood, R. M.; Saha, D.; McCarthy, L. A.; Tokarski, III, J. T.; Sanders, G. D.; Kuhns, P. L.; McGill, S. A.; Reyes, A. P.; Reno, J. L.; Stanton, C. J.; et al

    2014-10-29

    A combined experimental-theoretical study of optically pumped NMR (OPNMR) has been performed in a GaAs/Al0.1Ga0.9As quantum well film with thermally induced biaxial strain. The photon energy dependence of the Ga-71 OPNMR signal was recorded at magnetic fields of 4.9 and 9.4 T at a temperature of 4.8-5.4 K. The data were compared to the nuclear spin polarization calculated from differential absorption to spin-up and spin-down states of the conduction band using a modified Pidgeon Brown model. Reasonable agreement between theory and experiment is obtained, facilitating assignment of features in the OPNMR energy dependence to specific interband transitions. Despite the approximationsmore » made in the quantum-mechanical model and the inexact correspondence between the experimental and calculated observables, the results provide insight into how effects of strain and quantum confinement are manifested in OPNMR signals« less

  8. Effects of strain and quantum confinement in optically pumped nuclear magnetic resonance in GaAs: Interpretation guided by spin-dependent band structure calculations

    SciTech Connect

    Wood, R. M.; Saha, D.; McCarthy, L. A.; Tokarski, III, J. T.; Sanders, G. D.; Kuhns, P. L.; McGill, S. A.; Reyes, A. P.; Reno, J. L.; Stanton, C. J.; Bowers, C. R.

    2014-10-29

    A combined experimental-theoretical study of optically pumped NMR (OPNMR) has been performed in a GaAs/Al0.1Ga0.9As quantum well film with thermally induced biaxial strain. The photon energy dependence of the Ga-71 OPNMR signal was recorded at magnetic fields of 4.9 and 9.4 T at a temperature of 4.8-5.4 K. The data were compared to the nuclear spin polarization calculated from differential absorption to spin-up and spin-down states of the conduction band using a modified Pidgeon Brown model. Reasonable agreement between theory and experiment is obtained, facilitating assignment of features in the OPNMR energy dependence to specific interband transitions. Despite the approximations made in the quantum-mechanical model and the inexact correspondence between the experimental and calculated observables, the results provide insight into how effects of strain and quantum confinement are manifested in OPNMR signals

  9. Dynamics and relaxation of multiple quantum NMR coherences in a quasi-one-dimensional chain of nuclear spins 19F in calcium fluorapatite

    NASA Astrophysics Data System (ADS)

    Doronin, S. I.; Vasil'ev, S. G.; Samoilenko, A. A.; Fel'dman, E. B.; Shumm, B. A.

    2015-05-01

    Multiple quantum experiments on nuclear magnetic resonance on spins of 19F in calcium fluorapatite have been performed. It has been shown that more than 97% of the observed signal refers to the multiple quantum coherences of the zeroth and plus/minus second orders. The dependences of the intensities of these coherences on the time of the preparation period of the multiple quantum NMR experiment have been obtained. The dipole relaxation of multiple quantum coherences on the evolution period of the multiple quantum nuclear magnetic resonance experiment has been studied. A probe providing short radio-frequency pulses with the duration up to 0.3 ?s has been developed for experiments. The experimental results show that the studied system can be used for the transmission of quantum information and the study of the decoherence process in strongly correlated multispin clusters.

  10. Double-quantum homonuclear rotary resonance: Efficient dipolar recovery in magic-angle spinning nuclear magnetic resonance

    NASA Astrophysics Data System (ADS)

    Nielsen, N. C.; Bildse, H.; Jakobsen, H. J.; Levitt, M. H.

    1994-08-01

    We describe an efficient method for the recovery of homonuclear dipole-dipole interactions in magic-angle spinning NMR. Double-quantum homonuclear rotary resonance (2Q-HORROR) is established by fulfilling the condition ?r=2?1, where ?r is the sample rotation frequency and ?1 is the nutation frequency around an applied resonant radio frequency (rf) field. This resonance can be used for double-quantum filtering and measurement of homonuclear dipolar interactions in the presence of magic-angle spinning. The spin dynamics depend only weakly on crystallite orientation allowing good performance for powder samples. Chemical shift effects are suppressed to zeroth order. The method is demonstrated for singly and doubly 13C labeled L-alanine.

  11. Hyperfine Sublevel Correlation (HYSCORE) Spectra for Paramagnetic Centers with Nuclear Spin I = 1 Having Isotropic Hyperfine Interactions

    SciTech Connect

    Maryasov, Alexander G.; Bowman, Michael K.

    2004-07-08

    It is shown that HYSCORE spectra of paramagnetic centers having nuclei of spin I=1 with isotropic hfi and arbitrary NQI consist of ridges having zero width. A parametric presentation of these ridges is found which shows the range of possible frequencies in the HYSCORE spectrum and aids in spectral assignments and rapid estimation of spin Hamiltonian parameters. An alternative approach for the spectral density calculation is presented that is based on spectral decomposition of the Hamiltonian. Only the eigenvalues of the Hamiltonian are needed in this approach. An atlas of HYSCORE spectra is given in the Supporting Information. This approach is applied to the estimation of the spin Hamiltonian parameters of the oxovanadium-EDTA complex.

  12. Nuclear spin Hall and Klein tunneling effects during oxidation with electric and magnetic field inductions in graphene.

    PubMed

    Little, Reginald B; McClary, Felicia; Rice, Bria; Jackman, Corine; Mitchell, James W

    2012-12-14

    The recent observation of the explosive oxidation of graphene with enhancement for decreasing temperature and the requirements for synchronizing oxidants for collective oxidation-reduction (redox) reactions presented a chemical scenario for the thermal harvesting by the magnetic spin Hall Effect. More experimental data are presented to demonstrate such spin Hall Effect by determining the influence of spins of so-called spectator fermionic cations. Furthermore, the so-called spectator bosonic cations are discovered to cause a Klein tunneling effect during the redox reaction of graphene. The Na(+) and K(+), fermionic cations and the Mg(2+) and Ca(2+), bosonic cations were observed and compared under a variety of experimental conditions: adiabatic reactions with initial temperatures (18-22 C); reactions toward infinite dilution; isothermal reactions under nonadiabatic conditions at low temperature of 18 C; reactions under paramagnetic O(2) or diamagnetic N(2) atmospheres of different permeabilities; reactions in applied and no applied external magnetic field; and reactions toward excess concentrations of common and uncommon Na(+) and Mg(2+) cations. The observed reaction kinetics and dynamics under these various, diverse conditions are consistent with the spin Hall mechanism, energy harvesting and short time violation of Second Law of Thermodynamics for redox reactions of graphene by the Na(+)K(+) mixture and are consistent with the Klein tunnel mechanism for the redox reactions of graphene by the Mg(2+)Ca(2+) mixture. Mixed spin Hall and Klein tunnel mechanisms are discovered to slow and modulate explosive redox reactions. Such spin Hall Effect also gives explanation of recent tunneling of electrons through boron nitride. PMID:23108034

  13. Measuring the spin polarization of alkali-metal atoms using nuclear magnetic resonance frequency shifts of noble gases

    NASA Astrophysics Data System (ADS)

    Liu, X. H.; Luo, H.; Qu, T. L.; Yang, K. Y.; Ding, Z. C.

    2015-10-01

    We report a novel method of measuring the spin polarization of alkali-metal atoms by detecting the NMR frequency shifts of noble gases. We calculated the profile of 87Rb D1 line absorption cross sections. We then measured the absorption profile of the sample cell, from which we calculated the 87Rb number densities at different temperatures. Then we measured the frequency shifts resulted from the spin polarization of the 87Rb atoms and calculated its polarization degrees at different temperatures. The behavior of frequency shifts versus temperature in experiment was consistent with theoretical calculation, which may be used as compensative signal for the NMRG closed-loop control system.

  14. Limits on anomalous spin-spin couplings between neutrons.

    PubMed

    Glenday, Alexander G; Cramer, Claire E; Phillips, David F; Walsworth, Ronald L

    2008-12-31

    We report experimental limits on new spin-dependent macroscopic forces between neutrons. We measured the nuclear Zeeman frequencies of a 3He/129Xe maser while modulating the nuclear spin polarization of a nearby 3He ensemble in a separate glass cell. We place limits on the coupling strength of neutron spin-spin interactions mediated by light pseudoscalar particles like the axion [g(p)g(p)/(4pihc)] at the 3 x 10(-7) level for interaction ranges longer than about 40 cm. This limit is about 10(-5) the size of the magnetic dipole-dipole interaction between neutrons. PMID:19113768

  15. 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-Brnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  16. 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-Brnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  17. Nuclear magnetic resonance data of C17H16NCl3

    NASA Astrophysics Data System (ADS)

    Kalinowski, H.-O.; Kumar, M.; Gupta, V.; Gupta, R.

    This document is part of Part 1 `Aliphatic Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Brnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  18. Nuclear magnetic resonance data of C8H24OSSi4

    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-Brnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

  19. Rapid methods for the high yield synthesis of carbon-13 enriched intermediates of the pentose-phosphate pathway.

    PubMed

    Arora, K K; Collins, J G; MacLeod, J K; Williams, J F

    1988-07-01

    Methods for the synthesis of carbon-13 enriched substrates, intermediates and products of the pentose-phosphate pathway, viz. ribose, arabinose, xylulose and ribulose 5-phosphates, sedoheptulose mono- and bisphosphates, octulose (both the ido- and altro-epimers) mono- and bisphosphates, are described. The procedure of the classical Kiliani synthesis was adopted for the preparation of the two starting compounds, [1-13C]ribose and [1-13C]arabinose 5-phosphates. Using these initial reactants and enzymic methods involving the group-transferring enzymes, transketolase, aldolase and transaldolase, a variety of specifically 13C-labelled five-, six-, seven- and eight-carbon sugar phosphates were synthesized in high yield and purity. The isolation and authenticity of each of the 13C-labelled sugars were established by column, paper and thin layer chromatographic methods and specific enzymic assays. The purity and positional isotopic analysis of these sugar-P's were confirmed by 13C-NMR spectroscopy. These specifically 13C-enriched compounds are required for enzymatic, mechanistic and quantitative investigations of pentose-pathway reactions in animal, plant and tumour tissues in vitro and in vivo. PMID:3223986

  20. The role of atomic chlorine in glacial-interglacial changes in the carbon-13 content of atmospheric methane

    NASA Astrophysics Data System (ADS)

    Levine, J. G.; Wolff, E. W.; Jones, A. E.; Sime, L. C.

    2011-02-01

    The ice-core record of the carbon-13 content of atmospheric methane (?13CH4) has largely been used to constrain past changes in methane sources. The aim of this paper is to explore, for the first time, the contribution that changes in the strength of a minor methane sink?oxidation by atomic chlorine in the marine boundary layer (ClMBL)?could make to changes in ?13CH4 on glacial-interglacial timescales. Combining wind and temperature data from a variety of general circulation models with a simple formulation for the concentration of ClMBL, we find that changes in the strength of this sink, driven solely by changes in the atmospheric circulation, could have been responsible for changes in ?13CH4 of the order of 10% of the glacial-interglacial difference observed. We thus highlight the need to quantify past changes in the strength of this sink, including those relating to changes in the sea-ice source of sea salt aerosol.

  1. Generalized spin precession equations

    NASA Astrophysics Data System (ADS)

    Stckmann, Hans-Jrgen; Dubbers, Dirk

    2014-05-01

    The Bloch equations, which describe spin precession and relaxation in external magnetic fields, can be generalized to include the evolution of polarization tensors of various ranks in arbitrary multipole fields. We show applications of the generalized spin precession equations using simple examples from atomic, nuclear and condensed matter physics, and compare the various approaches found in the literature. The derivation of the generalized Bloch equations can be considerably simplified using a particular bra-ket notation for irreducible tensors.

  2. Nuclear spin-lattice relaxation at field-induced level crossings in a Cr8F8 pivalate single crystal

    NASA Astrophysics Data System (ADS)

    Yamamoto, Shoji

    2016-01-01

    We construct a microscopic theory for the proton spin-lattice relaxation-rate 1 / T1 measurements around field-induced level crossings in a single crystal of the trivalent chromium ion wheel complex [Cr8F8(OOCtBu)16] at sufficiently low temperatures [E. Micotti et al., Phys. Rev. B 72 (2005) 020405(R)]. Exactly diagonalizing a well-equipped spin Hamiltonian for the individual clusters and giving further consideration to their possible interactions, we reveal the mechanism of 1 / T1 being single-peaked normally at the first level crossing but double-peaked intriguingly around the second level crossing. We wipe out the doubt about poor crystallization and find out a solution-intramolecular alternating Dzyaloshinsky-Moriya interaction combined with intermolecular coupling of antiferromagnetic character, each of which is so weak as several tens of mK in magnitude.

  3. Heisenberg spin exchange effects of nitroxide radicals on Overhauser dynamic nuclear polarization in the low field limit at 1.5 mT

    NASA Astrophysics Data System (ADS)

    Lingwood, Mark D.; Ivanov, Ivan A.; Cote, Alissa R.; Han, Songi

    2010-05-01

    Nuclear magnetic resonance (NMR) and magnetic resonance imaging (MRI) at very low magnetic fields (0.05-20 mT) have gained interest due to the simple and portable magnet design and newly emerging applications outside of the usual laboratory setting. A method to enhance the NMR signal is needed due to the low thermal polarization of nuclear spins at these fields; dynamic nuclear polarization (DNP) via the Overhauser effect from free radicals is an attractive option. In this report we describe a DNP-enhanced NMR system operating at a fixed field of 1.5 mT and measure 1H signal enhancements of up to -350 fold during the saturation of a selected electron spin resonance (ESR) transition of dissolved nitroxide radicals. This -350 fold enhanced polarization is equivalent to what would be obtained by prepolarization in a 0.53 T field. The ESR spectra at varying radical concentrations are indirectly found through DNP-enhanced NMR detection. Here, ESR line broadening at higher radical concentrations due to Heisenberg electron spin exchange is observed. Enhancements in the limit of maximum power are reported as a function of concentration for three ESR transitions, and are found to increase with concentration. The >300 fold 1H NMR signal amplifications achievable at 1.5 mT will reduce experimental time by several orders of magnitude, permitting NMR relaxation, imaging or pulsed-field gradient diffusion experiments that are inaccessible without using the DNP effect at 1.5 mT. We demonstrate the potential benefit of such large signal amplification schemes through T1 and T2 relaxation measurements carried out in a much shorter time when employing DNP. Finally, we compare our results to those obtained in the earth's magnetic field and find that the signal to noise ratio (SNR) of DNP-enhanced signal at 1.5 mT is much greater than that obtained by previous studies utilizing DNP enhancement in the 0.05 mT earth's magnetic field.

  4. Nuclear-spin relaxation in paramagnetic complexes in the slow-motion regime for the electron spin: The anisotropic pseudorotation model for S=1 and the interpretation of nuclear magnetic relaxation dispersion results for a low-symmetry Ni(II) complex

    NASA Astrophysics Data System (ADS)

    Larsson, Tomas; Westlund, Per-Olof; Kowalewski, Jozef; Koenig, Seymour H.

    1994-07-01

    This work presents the anisotropic pseudorotation (APR) model, which is a new dynamic model for the interpretation of experimental nuclear spin-lattice relaxation times in paramagnetic (S=1) complexes of low symmetry. It comprises two dynamic processes active in modulating the zero-field splitting interaction (ZFS). Reorientation of the complex modulates a static zero-field splitting, defined as a measure of the asymmetry in the equilibrium geometry at the paramagnetic site. Local motions of the ligands surrounding the paramagnetic site further contribute a rapidly fluctuating (transient) zero-field splitting interaction. This dynamic model is evaluated within a general theoretical framework capable of dealing with the electron-spin system in the low- and high-magnetic field limits for both Redfield and slow-motion cases, i.e., where the motions inducing electron-spin relaxation and the electron-spin relaxation itself are characterized by the same time scale. The dynamic model is characterized and discussed by calculating results for a large number of parameter sets. The obtained results are compared with the traditional theory, the Solomon-Bloembergen-Morgan equations (SBM), by least-squares fitting the SBM equations to the APR model. Results show that in most cases the SBM model can fit the nuclear magnetic relaxation dispersion (NMRD) profiles from the APR model at the expense of using a different parameter set. For both models, a restricted fit to experimental NMRD data, from bis(2,2,6,6-tetramethyl-3,5-heptanedionato)Ni(II)(aniline-d5)2 (abbreviated Ni(dpm)2(aniline-d5)2 or simply NIDPM) in solution, has been performed. The parameters obtained suggest that NIDPM is a slow-motion case comprising a static contribution to its zero-field splitting, so that the SBM model is inapplicable.

  5. Ferromagnetic and antiferromagnetic spin-ordering stabilities of asymmetric nuclear matter: Lowest-order constrained variational method

    SciTech Connect

    Bigdeli, M.

    2010-11-15

    In this paper we study the possibility of spontaneous ferromagnetic and antiferromagnetic phase transitions of asymmetrical nuclear matter using the lowest-order constrained variational technique with AV{sub 18} potential and employing a microscopic point of view. Our results show that the spontaneous transition to ferromagnetic and antiferromagnetic phases cannot occur for asymmetric nuclear matter.

  6. Spin-bus concept of spin quantum computing

    SciTech Connect

    Mehring, Michael; Mende, Jens

    2006-05-15

    We present a spin-bus concept of quantum computing where an electron spin S=1/2 acts as a bus qubit connected to a finite number N of nuclear spins I=1/2 serving as client qubits. Spin-bus clusters are considered as local processing units and may be interconnected with other spin-bus clusters via electron-electron coupling in a scaled up version. Here we lay the ground for the basic functional unit with long qubit registers, provide the theory and experimental verification of correlated qubit states, and demonstrate the Deutsch algorithm. Experiments were performed on a qubyte plus one nuclear spin in a solid state system.

  7. Spin-orbit ZORA and four-component Dirac-Coulomb estimation of relativistic corrections to isotropic nuclear shieldings and chemical shifts of noble gas dimers.

    PubMed

    Jankowska, Marzena; Kupka, Teobald; Stobiński, Leszek; Faber, Rasmus; Lacerda, Evanildo G; Sauer, Stephan P A

    2016-02-01

    Hartree-Fock and density functional theory with the hybrid B3LYP and general gradient KT2 exchange-correlation functionals were used for nonrelativistic and relativistic nuclear magnetic shielding calculations of helium, neon, argon, krypton, and xenon dimers and free atoms. Relativistic corrections were calculated with the scalar and spin-orbit zeroth-order regular approximation Hamiltonian in combination with the large Slater-type basis set QZ4P as well as with the four-component Dirac-Coulomb Hamiltonian using Dyall's acv4z basis sets. The relativistic corrections to the nuclear magnetic shieldings and chemical shifts are combined with nonrelativistic coupled cluster singles and doubles with noniterative triple excitations [CCSD(T)] calculations using the very large polarization-consistent basis sets aug-pcSseg-4 for He, Ne and Ar, aug-pcSseg-3 for Kr, and the AQZP basis set for Xe. For the dimers also, zero-point vibrational (ZPV) corrections are obtained at the CCSD(T) level with the same basis sets were added. Best estimates of the dimer chemical shifts are generated from these nuclear magnetic shieldings and the relative importance of electron correlation, ZPV, and relativistic corrections for the shieldings and chemical shifts is analyzed. © 2015 Wiley Periodicals, Inc. PMID:26503739

  8. Use of carbon-13 as a population marker for Anopheles arabiensis in a sterile insect technique (SIT) context

    PubMed Central

    Hood-Nowotny, Rebecca; Mayr, Leo; Knols, Bart GJ

    2006-01-01

    Background Monitoring of sterile to wild insect ratios in field populations can be useful to follow the progress in genetic control programmes such as the Sterile Insect Technique (SIT). Of the numerous methods for marking insects most are not suitable for use in mass rearing and mass release. Suitable ones include dye marking, genetic marking and chemical marking. Methods The feasibility of using the stable isotope of carbon, 13C, as a potential chemical marker for Anopheles arabiensis was evaluated in the laboratory. Labeled-13C glucose was incorporated into the larval diet in a powder or liquid form. The contribution of adult sugar feeding to the total mosquito carbon pool and the metabolically active carbon pool was determined by tracing the decline of the enrichment of the adult male mosquito as it switched from a labeled larval diet to an unlabeled adult diet. This decline in the adult was monitored by destructive sampling of the whole mosquito and analyzed using isotope ratio mass spectrometry. Results A two-pool model was used to describe the decline of the 13C-enrichment of adult mosquitoes. The proportion of the total adult carbon pool derived from the adult sugar diet over the life span of mosquitoes was determined and the ratio of structural carbon, with a low turnover rate to metabolically active non-structural carbon was assessed. The uptake and turnover of sugar in the metabolically active fraction suggests that after 3 days >70% of the active fraction carbon is derived from sugar feeding (increasing to >90% by day 7), indicating the high resource demand of male mosquitoes. Conclusion It was possible to "fix" the isotopic label in adult An. arabiensis and to detect the label at an appropriate concentration up to 21 days post-emergence. The optimum labeling treatment would cost around 250 US$ per million mosquitoes. Stable isotope marking may thus aid research on the fate of released insects besides other population-based ecological studies. PMID:16445865

  9. Reconstriction of atmospheric carbon dioxide and isotopic carbon-13 dioxide from air occluded in ice cores from Greenland and Antarctica

    SciTech Connect

    Wahlen, M.

    1994-12-31

    Carbon dioxide (CO{sub 2}) dioxide (CO{sub 2}) mixing ratio and isotopic carbon-13 dioxide {delta}{sup 13}CO{sub 2} was measured in the air extracted form ice cores from Greenland (GISP 2, Greenland Ice Sheet Project 2) and from Antarctica (Vostok). The goals are to determine the phasing between temperature and atmospheric CO{sub 2} changes during periods of different climatic conditions and to gain insight into the mechanisms producing the observed CO{sub 2} variations. Experimentally, the dry extraction technique at low temperature for CO{sub 2} was used. The extracted air is then condensed quickly at 35{degrees}K and subsequently released into a cell, where the CO{sub 2} mixing ratio is determined by tunable diode infrared laser spectroscopy on a single vibrational-rotational transition in the 4.3-micrometer ({mu}m) band by measuring the absorbance relative to standards. Three standards are processed identically to samples with every three samples. The experimental uncertainty is {plus_minus}3 parts per million (ppm). {delta}{sup 13}/CO{sub 2} is measured in duplicate by using a dry air extraction technique similar to Etheridge, Pearman, and de Silva on larger samples. CO{sub 2} is separated cryogenically from the extracted air, and {delta}{sup 13}CO{sub 2} is measured by stable isotope ratio mass spectrometry. Severe extraction fractionation is observed. It is controlled and accounted for by admitting standard air samples over the ice; the standard air samples are then processed in the same manner as the extracted air samples are then processed in the same manner as the extracted air samples. The {delta}{sup 13}CO{sub 2} results are corrected for nitrous oxide mass interferences and for gravitational fractionation. The experimental uncertainty is better then {plus_minus}0.1 permil. 5 refs., 3 figs.

  10. 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, Vronique

    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

  11. A Cross-Polarization, Magic-Angle-Spinning, 13C-Nuclear-Magnetic-Resonance Study of Polysaccharides in Sugar Beet Cell Walls1

    PubMed Central

    Renard, Catherine M.G.C.; Jarvis, Michael C.

    1999-01-01

    Solid-state nuclear magnetic resonance relaxation experiments were used to study the rigidity and spatial proximity of polymers in sugar beet (Beta vulgaris) cell walls. Proton T1? decay and cross-polarization patterns were consistent with the presence of rigid, crystalline cellulose microfibrils with a diameter of approximately 3 nm, mobile pectic galacturonans, and highly mobile arabinans. A direct-polarization, magic-angle-spinning spectrum recorded under conditions adapted to mobile polymers showed only the arabinans, which had a conformation similar to that of beet arabinans in solution. These cell walls contained very small amounts of hemicellulosic polymers such as xyloglucan, xylan, and mannan, and no arabinan or galacturonan fraction closely associated with cellulose microfibrils, as would be expected of hemicelluloses. Cellulose microfibrils in the beet cell walls were stable in the absence of any polysaccharide coating. PMID:10198090

  12. Crocus sativus Petals: Waste or Valuable Resource? The Answer of High-Resolution and High-Resolution Magic Angle Spinning Nuclear Magnetic Resonance.

    PubMed

    Righi, Valeria; Parenti, Francesca; Tugnoli, Vitaliano; Schenetti, Luisa; Mucci, Adele

    2015-09-30

    Intact Crocus sativus petals were studied for the first time by high-resolution magic angle spinning nuclear magnetic resonance (HR-MAS NMR) spectroscopy, revealing the presence of kinsenoside (2) and goodyeroside A (3), together with 3-hydroxy-?-butyrolactone (4). These findings were confirmed by HR-NMR analysis of the ethanol extract of fresh petals and showed that, even though carried out rapidly, partial hydrolysis of glucopyranosyloxybutanolides occurs during extraction. On the other hand, kaempferol 3-O-sophoroside (1), which is "NMR-silent" in intact petals, is present in extracts. These results suggest to evaluate the utilization of saffron petals for phytopharmaceutical and nutraceutical purposes to exploit a waste product of massive production of commercial saffron and point to the application of HR-MAS NMR for monitoring bioactive compounds directly on intact petals, avoiding the extraction procedure and the consequent hydrolysis reaction. PMID:26367873

  13. Geometrical spin symmetry and spin

    SciTech Connect

    Pestov, I. B.

    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.

  14. High-pressure, high-temperature magic angle spinning nuclear magnetic resonance devices and processes for making and using same

    SciTech Connect

    Hu, Jian Zhi; Hu, Mary Y.; Townsend, Mark R.; Lercher, Johannes A.; Peden, Charles H. F.

    2015-10-06

    Re-usable ceramic magic angle spinning (MAS) NMR rotors constructed of high-mechanic strength ceramics are detailed that include a sample compartment that maintains high pressures up to at least about 200 atmospheres (atm) and high temperatures up to about least about 300.degree. C. during operation. The rotor designs minimize pressure losses stemming from penetration over an extended period of time. The present invention makes possible a variety of in-situ high pressure, high temperature MAS NMR experiments not previously achieved in the prior art.

  15. Spin echoes of nuclear magnetization diffusing in a constant magnetic field gradient and in a restricted geometry

    SciTech Connect

    Sen, P.N.; Andre, A.; Axelrod, S.

    1999-10-01

    We study the influence of restriction on Carr{endash}Purcell{endash}Meiboom{endash}Gill spin echoes response of magnetization of spins diffusing in a bounded region in the presence of a constant magnetic field gradient. Depending on three main length scales: L{sub S} pore size, L{sub G} dephasing length and L{sub D} diffusion length during half-echo time, three main regimes of decay have been identified: free, localization and motionally averaging regime. In localization regime, the decay exponent depends on a fractional power (2/3) of the gradient, denoting a strong breakdown of the second cumulant or the Gaussian phase approximation (GPA). In the other two regimes, the exponent depends on the gradient squared, and the GPA holds. We find that the transition from the localization to the motionally averaging regime happens when the magnetic field gradients approach special values, corresponding to branch points of the eigenvalues. Transition from one regime to another as a function of echo number for a certain range of parameters is discussed. In this transition region, the signal shows large oscillations with echo number. For large n, asymptotic behavior sets in as a function of n for the decay exponent per echo. This is true for all values of the parameters L{sub S}, L{sub G}, and L{sub D}. {copyright} {ital 1999 American Institute of Physics.}

  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. Nuclear structure explored by ?-delayed decay spectroscopy of spin-polarized radioactive nuclei at TRIUMF ISAC-1. Intruder configurations in 29Mg and 30Mg, the nuclei in the region of island of inversion

    NASA Astrophysics Data System (ADS)

    Shimoda, T.; Tajiri, K.; Kura, K.; Odahara, A.; Suga, M.; Hirayama, Y.; Imai, N.; Miyatake, H.; Pearson, M.; Levy, C. D. P.; Jackson, K. P.; Legillon, R.; Petrache, C.; Fukuchi, T.; Hamatani, N.; Hori, T.; Kazato, M.; Kenmoku, Y.; Masue, T.; Nishibata, H.; Suzuki, T.; Takashima, A.; Yokoyama, R.

    2014-01-01

    Spin-polarized radioactive nuclear beams at TRIUMF enable a new spectroscopic method which efficiently assigns spins and parities of the daughter levels by taking advantage of the asymmetric ?-decay of the polarized parent nucleus. This method was successfully applied to structure studies of 29Mg and 30Mg in connection with the physics of the "island of inversion". In 29Mg, two low-lying levels with intruder configuration were assigned. In 30Mg, coexistence of spherical shape, prolate shape and ?-collectivity was strongly suggested.

  18. On Spin Fluctuations in Dense Matter and Skyrme Interactions

    SciTech Connect

    Sagawa, H.; Margueron, J.

    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.

  19. Nuclear spin polarization of 3He atoms with a frequency doubled Ti:sapphire laser toward nuclear magnetic resonance of porous media

    NASA Astrophysics Data System (ADS)

    Tabata, Y.; Yamada, H.; Maeda, S.; Morioka, H.; Kumagai, H.; Kobayashi, A.

    2010-02-01

    NMR based on laser-polarized 3He gases has been attracted as a powerful tool for characterizing physical parameters of porous media and then imaging human lungs. In this paper, the feasibility study of nuclear polarization of 3He atoms utilizing the 23S-33P transition at 389 nm is reported in comparison with the conventional 23S-23P transition at 1083 nm. The 389-nm light has been available readily with the development of various indium gallium nitride light-emitting diodes (InGaN LEDs). In this work, the frequency-doubled light of a 778-nm CW Ti:sapphire laser with the nonlinear crystal (BiB3O6) was used as the optical pumping light at 389 nm. The other light from a Littrow external cavity diode laser was also used for optical pumping at the 1083-nm wavelength and then measurement of the nuclear polarization. The nuclear polarization of 1.8% with optical pumping at the 23S-33P transition was demonstrated and then it was found that the (23S1, F=1/2)-(33P0, F=1/2) transition was the most efficient transition of 23S-33P lines for the magnetic field of 1.6 mT and the gas pressure of 0.5 Torr.

  20. Electron Spin Dynamics in Semiconductor Quantum Dots

    SciTech Connect

    Marie, X.; Belhadj, T.; Urbaszek, B.; Amand, T.; Krebs, O.; Lemaitre, A.; Voisin, P.

    2011-07-15

    An electron spin confined to a semiconductor quantum dot is not subject to the classical spin relaxation mechanisms known for free carriers but it strongly interacts with the nuclear spin system via the hyperfine interaction. We show in time resolved photoluminescence spectroscopy experiments on ensembles of self assembled InAs quantum dots in GaAs that this interaction leads to strong electron spin dephasing.

  1. 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.

  2. 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.

  3. 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?

  4. Nuclear spin phonon relaxation by Raman process in Na 3H(SO 4) 2 single crystals with the electric-quadrupole-type interaction using 1H and 23Na NMR

    NASA Astrophysics Data System (ADS)

    Lim, Ae Ran; Shin, Chang Woo

    2008-11-01

    Successive phase transitions in a Na 3H(SO 4) 2 single crystal were found at 296, 513, and 533 K. To investigate the mechanism of the phase transition at 296 K, the 1H and 23Na spin-lattice relaxation time and the spin-spin relaxation time of Na 3H(SO 4) 2 were measured near the phase transition temperature using a FT NMR spectrometer. The spin-lattice relaxation time, T1, for 1H in Na 3H(SO 4) 2 crystals exhibits a minimum below TC1 (=296 K) indicating the presence of distinct molecular motion governed by the Bloembergen-Purcell-Pound (BPP) theory. Although the results for the 1H and 23Na relaxation times provide no evidence of the phase transition at TC1, the separation of the 23Na resonance lines changes abruptly at TC1. The phase transition at 296 K produces a change in the separation of the Na resonance line that is associated with a change in the atomic positions in the vicinity of the Na ions. Also, the nuclear spin-lattice relaxation process in Na 3H(SO 4) 2 crystals with the electric-quadrupole-type interaction proceed via Raman process. These results are compared with those obtained for other M 3H(SO 4) 2 (M=K, Rb, and Cs) crystals, which have similar hydrogen-bonded structures.

  5. High Dispersion Near-infrared Spectra of Comet C/2004 Q2 (Machholz) By Keck-II/NIRSPEC: Organic Chemistry, Nuclear Spin Temperatures and D/H Ratio

    NASA Astrophysics Data System (ADS)

    Kawakita, Hideyo; Kobayashi, H.

    2008-09-01

    We present high dispersion near-infrared spectra of comet C/2004 Q2 (Machholz) taken by using NIRSPEC spectrograph at the Keck-II telescope on Jan 30, 2005. Comet Machholz is an Oort cloud comet and its perihelion passage was in late Jan 2005. Thanks to the brightness of the comet, very high S/N ratio spectra were obtained in L-band. Many emission lines from parent and daughter molecules were detected in our spectra: H2O, OH, HCN, NH2, C2H2, CH4, C2H6, H2CO, CH3OH. NH3 was probably detected but its emission lines were contaminated with NH2 lines. Gas production rates and mixing ratios of the molecules were determined from the spectra. The mixing ratios in the comet are almost normal compared to other Oort cloud comets. Furthermore, constraints to nuclear spin temperatures of both H2O and CH4, and to the D/H ratio in methane were also obtained. Origin of icy materials in C/2004 Q2 (Machholz) will be discussed based on these results.

  6. Black Hole-Neutron Star Mergers with a Hot Nuclear Equation of State: Outflow and Neutrino-cooled Disk for a Low-mass, High-spin Case

    NASA Astrophysics Data System (ADS)

    Deaton, M. Brett; Duez, Matthew D.; Foucart, Francois; O'Connor, Evan; Ott, Christian D.; Kidder, Lawrence E.; Muhlberger, Curran D.; Scheel, Mark A.; Szilagyi, Bela

    2013-10-01

    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 ? neutron star, 5.6 M ? black hole), high-spin (black hole J/M 2 = 0.9) system with the K 0 = 220 MeV Lattimer-Swesty EOS. We find that about 0.08 M ? of nuclear matter is ejected from the system, while another 0.3 M ? 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 Ye 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 ? ~ 1054 erg s-1), but the neutrino luminosity decreases by an order of magnitude over 50 ms of post-merger evolution.

  7. Nuclear spin transitions in the kHz range in Rydberg matter clusters give precise values of the internal magnetic field from orbiting Rydberg electrons

    NASA Astrophysics Data System (ADS)

    Holmlid, Leif

    2009-03-01

    Clusters of the electronically excited condensed matter Rydberg matter (RM) are planar and sixfold symmetric with specific magic numbers N as shown by rotational spectroscopy of potassium K N clusters [L. Holmlid, Mol. Phys. 105 (2007) 933; L. Holmlid, J. Mol. Struct. 885 (2008) 122]. In radio frequency emission spectra from such clusters, features are observed that are due to the hyperfine interaction between the atomic nucleus 39K and two Rydberg electrons. These electrons exist in a doubly excited K atom at n″ = 5 or 6 in a "sleeping-top" type rotating cluster. Such low excited electrons were observed recently in optical intra-cavity experiments in K(RM), where the electrons in the conduction band are involved in the angular momentum conservation in the stimulated emission. Here we show that the agreement with the theoretical description of circular Rydberg states is excellent within ±0.2% in the magnetic field, invoking angular momentum conservation by electrons in the condensed phase. Sleeping-top clusters may form stacks of clusters, and it is likely that such stacks are the emitting entities involved in the two nuclear spin series observed.

  8. A low-temperature crossover in water dynamics in an aqueous LiCl solution: diffusion probed by neutron spin-echo and nuclear magnetic resonance.

    PubMed

    Mamontov, E; Faraone, A; Hagaman, E W; Han, K S; Fratini, E

    2010-12-23

    Aqueous solutions of lithium chloride are an excellent model system for studying the dynamics of water molecules down to low temperatures without freezing. The apparent dynamic crossover observed in an aqueous solution of LiCl at about 220 to 225 K [Mamontov, JPCB 2009, 113, 14073] is located practically at the same temperature as the crossover found for pure water confined in small hydrophilic pores. This finding suggests a strong similarity of water behavior in these two types of systems. At the same time, studies of solutions allow more effective explorations of the long-range diffusion dynamics, because the water molecules are not confined inside an impenetrable matrix. In contrast to the earlier incoherent quasielastic neutron scattering results obtained for the scattering momentum transfers of 0.3 (-1) ? Q ? 0.9 (-1), our present incoherent neutron spin-echo measurements at a lower Q of 0.1 (-1) exhibit no apparent crossover in the relaxation times down to 200 K. At the same time, our present nuclear magnetic resonance measurements of the diffusion coefficients clearly show a deviation at the lower temperatures from the non-Arrhenius law obtained at the higher temperatures. Our results are consistent with a scenario in which more than one relaxational component may exist below the temperature of the dynamic crossover in water. PMID:21117619

  9. (77)Se nuclear spin-lattice relaxation in binary Ge-Se glasses: insights into floppy versus rigid behavior of structural units.

    PubMed

    Sen, Sabyasachi; Kaseman, Derrick C; Hung, Ivan; Gan, Zhehong

    2015-04-30

    The mechanism of (77)Se nuclear spin-lattice relaxation is investigated in binary Ge-Se glasses. The (77)Se nuclides in Se-Se-Se chain sites relax faster via dipolar coupling fluctuation compared to those in Ge-Se-Ge sites shared by GeSe4 tetrahedra that relax slower via the fluctuation of the chemical shift anisotropy. The relaxation rate for the Se-Se-Se sites decreases markedly with increasing magnetic field, whereas that for the Ge-Se-Ge sites displays no appreciable dependence on the magnetic field such that the extent of differential relaxation between the two Se environments becomes small at high fields on the order of 19.6 T. The corresponding dynamical correlation time is three orders of magnitude shorter (∼10(-9) s) for the Se-Se-Se sites, compared to that for the Ge-Se-Ge sites (∼10(-6) s). The large decoupling in the time scale between these Se environments provides direct experimental support to the commonly made assumption that the selenium chains are mechanically floppy, and the interconnected GeSe4 tetrahedra form the rigid elements in the selenide glass structure. PMID:25848959

  10. Characterization of metabolic profile of intact non-tumor and tumor breast cells by high-resolution magic angle spinning nuclear magnetic resonance spectroscopy.

    PubMed

    Maria, Roberta M; Altei, Wanessa F; Andricopulo, Adriano D; Becceneri, Amanda B; Cominetti, Márcia R; Venâncio, Tiago; Colnago, Luiz A

    2015-11-01

    (1)H high-resolution magic angle spinning nuclear magnetic resonance ((1)H HR-MAS NMR) spectroscopy was used to analyze the metabolic profile of an intact non-tumor breast cell line (MCF-10A) and intact breast tumor cell lines (MCF-7 and MDA-MB-231). In the spectra of MCF-10A cells, six metabolites were assigned, with glucose and ethanol in higher concentrations. Fifteen metabolites were assigned in MCF-7 and MDA-MB-231 (1)H HR-MAS NMR spectra. They did not show glucose and ethanol, and the major component in both tumor cells was phosphocholine (higher in MDA-MB-231 than in MCF-7), which can be considered as a tumor biomarker of breast cancer malignant transformation. These tumor cells also show acetone signal that was higher in MDA-MB-231 cells than in MCF-7 cells. The high acetone level may be an indication of high demand for energy in MDA-MB-231 to maintain cell proliferation. The higher acetone and phosphocholine levels in MDA-MB-231 cells indicate the higher malignance of the cell line. Therefore, HR-MAS is a rapid reproducible method to study the metabolic profile of intact breast cells, with minimal sample preparation and contamination, which are critical in the analyses of slow-growth cells. PMID:26247715

  11. Nuclear properties of the exotic high-spin isomer [sup 178]Hf[sup m2] from collinear laser spectroscopy

    SciTech Connect

    Boos, N.; Le Blanc, F.; Krieg, M.; Pinard, J.; Huber, G.; Lunney, M.D.; Le Du, D.; Meunier, R.; Hussonnois, M.; Constantinescu, O.; Kim, J.B.; Briancon, C.; Crawford, J.E.; Duong, H.T.; Gangrski, Y.P.; Kuehl, T.; Markov, B.N.; Oganessian, Y.T.; Quentin, P.; Roussiere, B.; Sauvage, J. Institut de Physique Nucleaire, Institut National de Physique Nucleair e et de Physique des Particules Centre National de la Recherche Scientique, 91406 Orsay Laboratoire Aime Cotton, 91405 Orsay Centre de Spectrometrie Nucleaire et de Spectrometrie de MasseOrsay, Institut de Physique Nucleaire, Institut National de Physique Nucleaire et de Physique des Particules Centre National de la Recherche Scientique, 91406 Orsay Gesselschaft fuer Schwerionenforschung Darmstadt m.b.H., 64291 Darmstadt Foster Radiation Laboratory, McGill University, Montreal, Quebec Joint Institute for Nuclear Research, D

    1994-04-25

    The complete hyperfine spectrum in the optical transition 5[ital d][sup 2]6[ital s][sup 2] [sup 3][ital P][sub 2][r arrow]5[ital d]6[ital s][sup 2]6[ital p] [sup 1][ital P][sub 1] of [sup 178]Hf[sup m2] was recorded by collinear laser spectroscopy using nanogram amounts of samples. The quadrupole moment and isomer shift were determined for the first time as well as a precise value and the sign of the magnetic dipole moment. The change in nuclear mean-square charge radius between the isomeric state [sup 178]Hf[sup m2] and the ground state [sup 178]Hf[sup [ital g

  12. A modified Bloembergen Purcell Pound model for nuclear spin relaxation of hydrogen in the C15 AB2 structure: TaV2Hx and ZrCr2Hx

    NASA Astrophysics Data System (ADS)

    Sholl, C. A.

    2005-12-01

    The BPP model for nuclear spin relaxation is modified to account rigorously for jumps of hydrogen within g site hexagons in the C15 AB2 structure. The theory is applied to proton relaxation data for low H concentrations in TaV2Hx and ZrCr2Hx. It is shown that the data are consistent with the results of quantum diffusion calculations, diffusivity measurements and H-H interaction effects deduced from quasielastic neutron scattering experiments.

  13. Revealing spin-spin correlations in atomic vapors and semiconductor heterostructures using spin noise spectroscopy

    NASA Astrophysics Data System (ADS)

    Roy, Dibyendu; Sinitsyn, Nikolai A.

    2014-03-01

    We discuss advantages and limitations of the spin noise spectroscopy for characterization of spin-spin correlations in various atomic vapors and semiconductor heterostructures. It is shown that all the relevant parameters of the quantum dot molecules including tunneling amplitudes with spin-conserving and spin-non-conserving interactions, decoherence rates, Coulomb repulsions, anisotropic g-factors and the distance between the dots can be determined by measuring properties of the spin noise power spectrum using a single linearly polarized detuned continuous-wave laser beam. Next we show that spin-spin interactions between two different species in an atomic vapor mixture can be revealed by measuring spin noise power spectrum with two laser beams. Finally we mention some relevant advances in spin noise spectroscopy for characterization of many-body interactions in correlated materials. This work was supported by the National Nuclear Security Administration of the U.S. DOE at LANL under Contract No. DE-AC52-06NA25396, and the LDRD Program at LANL

  14. Spin Technologies in Silicon Carbide

    NASA Astrophysics Data System (ADS)

    Klimov, Paul

    2015-03-01

    Over the past several decades SiC has evolved from being a simple abrasive to a versatile material platform for high-power electronics, optoelectronics, and nanomechanical devices. These technologies have been driven by advanced growth, doping, and processing capabilities, and the ready availability of large-area, single-crystal SiC wafers. Recent advances have also established SiC as a promising host for a novel class of technologies based on the spin of intrinsic color centers. In particular, the divacancies and related defects have ground-state electronic-spin triplets with ms-long coherence times that can be optically addressed near telecom wavelengths and manipulated with magnetic, electric, and strain fields. Recently, divacancy addressability has been extended to the single defect level, laying foundation for single spin technologies in SiC. This rapidly developing field has prompted research into the SiC material host to understand how defect-bound electron spins interact with their surrounding nuclear spin bath. Although nuclear spins are typically a major source of decoherence in color-center spin systems, they are also an important resource since they interact with magnetic fields orders of magnitude more weakly than electronic spins. This fact has motivated their use for quantum memories and ultra-sensitive sensors. In this talk I will review advances in this rapidly developing field and discuss our efforts towards this latter goal. This work was supported by the AFOSR, DARPA, and the NSF.

  15. Basic spin physics.

    PubMed

    Pipe, J G

    1999-11-01

    Magnetic resonance imaging is fundamentally a measurement of the magnetism inherent in some nuclear isotopes; of these the proton, or hydrogen atom, is of particular interest for clinical applications. The magnetism in each nucleus is often referred to as spin. A strong, static magnetic field B0 is used to align spins, forming a magnetic density within the patient. A second, rotating magnetic field B1 (RF pulse) is applied for a short duration, which rotates the spins away from B0 in a process called excitation. After the spins are rotated away from B0, the RF pulse is turned off, and the spins precess about B0. As long as the spins are all pointing in the same direction at any one time (have phase coherence), they act in concert to create rapidly oscillating magnetic fields. These fields in turn create a current in an appropriately placed receiver coil, in a manner similar to that of an electrical generator. The precessing magnetization decays rapidly in a duration roughly given by the T2 time constant. At the same time, but at a slower rate, magnetization forms again along the direction of B0; the duration of this process is roughly expressed by the T1 time constant. The precessional frequency of each spin is proportional to the magnetic field experienced at the nucleus. Small variations in this magnetic field can have dramatic effects on the MR image, caused in part by loss of phase coherence. These magnetic field variations can arise because of magnet design, the magnetic properties (susceptibility) of tissues and other materials, and the nuclear environment unique to various sites within any given molecule. The loss of phase coherence can be effectively eliminated by the use of RF refocusing pulses. Conventional MR imaging experiments can be characterized as either gradient echo or spin echo, the latter indicating the use of a RF refocusing pulse, and by the parameters TR, TE, and flip angle alpha. Tissues, in turn, are characterized by their individual spin density, M0, and by the T1, T2, and T2* time constants. Knowledge of these parameters allows one to calculate the resulting signal from a given tissue for a given MR imaging experiment. PMID:10631671

  16. Synthesis of empagliflozin, a novel and selective sodium-glucose co-transporter-2 inhibitor, labeled with carbon-14 and carbon-13.

    PubMed

    Hrapchak, Matt; Latli, Bachir; Wang, Xiao-Jun; Lee, Heewon; Campbell, Scot; Song, Jinhua J; Senanayake, Chris H

    2014-10-01

    Empagliflozin, (2S,3R,4R,5S,6R)-2-[4-chloro-3-[[4-[(3S)-oxolan-3-yl]oxyphenyl]methyl]phenyl]-6-(hydroxymethyl)oxane-3,4,5-triol was recently approved by the FDA for the treatment of chronic type 2 diabetes mellitus. Herein, we report the synthesis of carbon-13 and carbon-14 labeled empagliflozin. Carbon-13 labeled empagliflozin was prepared in five steps and in 34% overall chemical yield starting from the commercially available ?-D-glucose-[(13)C6]. For the radiosynthesis, the carbon-14 atom was introduced in three different positions of the molecule. In the first synthesis, Carbon-14 D-(+)-gluconic acid ?-lactone was used to prepare specifically labeled empagliflozin in carbon-1 of the sugar moiety in four steps and in 19% overall radiochemical yield. Carbon-14 labeled empagliflozin with the radioactive atom in the benzylic position was obtained in eight steps and in 7% overall radiochemical yield. In the last synthesis carbon-14 uniformly labeled phenol was used to give [(14)C]empagliflozin in eight steps and in 18% overall radiochemical yield. In all these radiosyntheses, the specific activities of the final compounds were higher than 53?mCi/mmol, and the radiochemical purities were above 98.5%. PMID:25332189

  17. Efficient Transformation of Parahydrogen Spin Order into Heteronuclear Magnetization

    PubMed Central

    Cai, Chong; Coffey, Aaron M.; Shchepin, Roman V.; Chekmenev, Eduard Y.; Waddell, Kevin W.

    2015-01-01

    Spin order obtained in the strong coupling regime of protons from parahydrogen-induced hyperpolarization (PHIP) is initially captured as an ensemble of singlet states. For biomedical applications of PHIP, locking this spin order on long-lived heteronuclear storage nuclei increases spectral dispersion, reduces background interference from water protons, and eliminates the need to synchronize subsequent detection pulse sequences to accrued singlet-state evolution. A variety of traditional sequences such as INEPT or HMQC are available to interconvert heteronuclear single quantum coherences at high field, but new approaches are required for converting singlet states into heteronuclear single quantum coherences at low field in the strong coupling regime of protons. Described here is a consolidated pulse sequence that achieves this transformation of singlet-state spin order into heteronuclear magnetization across a wide range of scalar couplings in AA?X spin systems. Analytic solutions to the spin evolution are presented, and performance was validated experimentally in the parahydrogen addition product, 2-hydroxyethyl 1-13C-propionate-d3. Hyperpolarized carbon-13 signals were enhanced by a factor of several million relative to Boltzmann polarization in a static magnetic field of 47.5 mT (~13% polarization). We anticipate that this pulse sequence will provide efficient conversion of parahydrogen spin order over a broad range of emerging PHIP agents that feature AA?X spin systems. PMID:23214962

  18. Quantum measurement of a mesoscopic spin ensemble

    SciTech Connect

    Giedke, G.; Taylor, J. M.; Lukin, M. D.; D'Alessandro, D.; Imamoglu, A.

    2006-09-15

    We describe a method for precise estimation of the polarization of a mesoscopic spin ensemble by using its coupling to a single two-level system. Our approach requires a minimal number of measurements on the two-level system for a given measurement precision. We consider the application of this method to the case of nuclear-spin ensemble defined by a single electron-charged quantum dot: we show that decreasing the electron spin dephasing due to nuclei and increasing the fidelity of nuclear-spin-based quantum memory could be within the reach of present day experiments.

  19. 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 Spearmans 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

  20. 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.; Foucart, Francois; O'Connor, Evan; Ott, Christian D.; Scheel, Mark A.; Szilagyi, Bela; Kidder, Lawrence E.; Muhlberger, Curran D. E-mail: m.duez@wsu.edu

    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 ν} ∼ 10{sup 54} erg s{sup –1}), but the neutrino luminosity decreases by an order of magnitude over 50 ms of post-merger evolution.

  1. Magic Angle Spinning Nuclear Magnetic Resonance Characterization of Voltage-Dependent Anion Channel Gating in Two-Dimensional Lipid Crystalline Bilayers

    PubMed Central

    2015-01-01

    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 13C–13C 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 Cβ in the N-terminal helix and S193 Cβ 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 13C–13C 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

  2. Spin symmetry in the antinucleon spectrum.

    PubMed

    Zhou, Shan-Gui; Meng, Jie; Ring, P

    2003-12-31

    We discuss spin and pseudospin symmetry in the spectrum of single nucleons and single antinucleons in a nucleus. As an example we use relativistic mean field theory to investigate single antinucleon spectra. We find a very well developed spin symmetry in single antineutron and single antiproton spectra. The dominant components of the wave functions of the spin doublet are almost identical. This spin symmetry in antiparticle spectra and the pseudospin symmetry in particle spectra have the same origin. However, it turns out that the spin symmetry in antinucleon spectra is much better developed than the pseudospin symmetry in normal nuclear single particle spectra. PMID:14754045

  3. Optoelectronic spin memories of electrons in semiconductors

    NASA Astrophysics Data System (ADS)

    Miah, M. Idrish

    2016-03-01

    We optically generate electron spins in semiconductors and apply an external magnetic field perpendicularly to them. Time-resolved photoluminescence measurements, pumped with a circularly polarized light, are performed to study the spin polarization and spin memory times in the semiconducting host. The measured spin polarization is found to be an exponential decay with the time delay of the probe. It is also found that the spin memory times, extracted from the polarization decays, enhance with the strength of the external magnetic field. However, at higher fields, the memory times get saturated to sub- μs because of the coupling for interacting electrons with the local nuclear field.

  4. Spin dynamics simulation of electron spin relaxation in Ni2 +(aq)

    NASA Astrophysics Data System (ADS)

    Rantaharju, Jyrki; Mare, Ji?; Vaara, Juha

    2014-07-01

    The ability to quantitatively predict and analyze the rate of electron spin relaxation of open-shell systems is important for electron paramagnetic resonance and paramagnetic nuclear magnetic resonance spectroscopies. We present a combined molecular dynamics (MD), quantum chemistry (QC), and spin dynamics simulation method for calculating such spin relaxation rates. The method is based on the sampling of a MD trajectory by QC calculations, to produce instantaneous parameters of the spin Hamiltonian used, in turn, to numerically solve the Liouville-von Neumann equation for the time evolution of the spin density matrix. We demonstrate the approach by simulating the relaxation of electron spin in an aqueous solution of Ni2 + ion. The spin-lattice (T1) and spin-spin (T2) relaxation rates are extracted directly from the simulations of the time dependence of the longitudinal and transverse magnetization, respectively. Good agreement with the available, indirectly obtained experimental data is obtained by our method.

  5. 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.

    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.

  6. Carbon-13 chemical-shift tensors in indigo: A two-dimensional NMR-ROCSA and DFT Study.

    PubMed

    Holmes, Sean T; Dybowski, Cecil

    2015-11-01

    The principal components of the (13)C NMR chemical-shift tensors for the eight unique carbon sites of crystalline indigo have been measured using the ROCSA pulse sequence. The chemical shifts have been assigned unambiguously to their respective nuclear sites through comparison of the experimental data to the results of density-functional calculations employing a refined X-ray diffraction structure. These measurements expand the database of measured aromatic (13)C chemical-shift tensors to the indole ring. Magnetic shielding calculations for hypoxanthine and adenosine are also reported. Comparisons of calculations that include the effect of the crystalline lattice with calculations that model indigo as an isolated molecule give an estimate of the intermolecular contribution to the magnetic shielding. PMID:26344134

  7. A conformational study of adenylyl-(3',5')-adenosine and adenylyl-(2',5')-adenosine in aqueous solution by carbon-13 magnetic resonance spectroscopy.

    PubMed Central

    Schleich, T; Cross, B P; Smith, I C

    1976-01-01

    The solution conformation of adenylyl-(3',5')-adenosine and adenylyl-(2',5')-adenosine in both the stacked and unstacked states was studied by carbon-13 magnetic resonance spectroscopy. Large chemical shift differences between the base carbons in the dimers and those in the corresponding monomers are attributed in part to the influence of base-base interaction. Carbon-phosphorus couplings across three bonds revealed the preferred populations for certain backbone rotamers, demonstrating that significant changes in conformation about the "c(3')-O and C(5')-O bonds do not occur in the temperature or salt-induced unstacking of adenylyl-(3',5')-adenosine. However, rotations about the C(2')-O and C(5')-O bonds occur in the temperature-mediated unstacking of adenylyl-(2',5')-adenosine. PMID:1257051

  8. Non-equilibrium spin polarization via real-time control of spin fluctuations in a semiconductor nanowire

    NASA Astrophysics Data System (ADS)

    Peddibhotla, Phani; Xue, Fei; Hauge, Ikaros; Bakkers, Erik; Poggio, Martino

    2013-03-01

    The implementation of electron spins as solid-state qubits suffers from decoherence due to its hyperfine interaction with the surrounding mesoscopic nuclear spin environment. Several methods such as complete polarization or narrowing of the nuclear spin ensemble have been proposed in order to address this issue. These proposals have been realized in quantum dots using an optical or electrical readout of the nuclear magnetic field. Here we demonstrate a similar control over a nanoscale ensemble of spins using the mechanical readout of magnetic resonance force microscopy (MRFM). We employ the exceptional sensitivity of MRFM to perform real-time measurement and control of an ensemble containing 105 nuclear spins in a semiconductor nanowire. We create hyperpolarized and narrowed nuclear spin states by harnessing the statistical fluctuations of the ensemble. Furthermore, we capture large nuclear polarization fluctuations, store them for many seconds, and read the polarization out.

  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. Spin resonance without spin splitting

    NASA Astrophysics Data System (ADS)

    Hell, M.; Sothmann, B.; Leijnse, M.; Wegewijs, M. R.; König, J.

    2015-05-01

    We predict that a single-level quantum dot without discernible splitting of its spin states develops a spin-precession resonance in charge transport when embedded into a spin valve. The resonance occurs in the generic situation of Coulomb blockaded transport with ferromagnetic leads whose polarizations deviate from perfect antiparallel alignment. The resonance appears when electrically tuning the interaction-induced exchange field perpendicular to one of the polarizations—a simple condition relying on vectors in contrast to usual resonance conditions associated with energy splittings. The spin resonance can be detected by stationary d I /d V spectroscopy and by oscillations in the time-averaged current using a gate-pulsing scheme. The generic noncollinearity of the ferromagnets and junction asymmetry allow for an all-electric determination of the spin-injection asymmetry, the anisotropy of spin relaxation, and the magnitude of the exchange field. We also investigate the impact of a nearby superconductor on the resonance position. Our simplistic model turns out to be generic for a broad class of coherent few-level quantum systems.

  11. /sup 13/C nuclear magnetic resonance studies of the biosynthesis by Microbacterium ammoniaphilum of L-glutamate selectively enriched with carbon-13

    SciTech Connect

    Walker, T.E.; Han, C.H.; Kollman, V.H.; London, R.E.; Matwiyoff, N.A.

    1982-02-10

    /sup 13/C NMR of isotopically enriched metabolites has been used to study the metabolism of Microbacterium ammoniaphilum, a bacterium which excretes large quantities of L-glutamic acid into the medium. Biosynthesis from 90% (1-/sup 13/C) glucose results in relatively high specificity of the label, with (2,4-/sup 13/C/sub 2/) glutamate as the major product. The predominant biosynthetic pathway for synthesis of glutamate from glucose was determined to be the Embden Meyerhof glycolytic pathway followed by P-enolpyruvate carboxylase and the first third of the Krebs cycle. Different metabolic pathways are associated with different correlations in the enrichment of the carbons, reflected in the spectrum as different /sup 13/C-/sup 13/C scalar multiplet intensities. Hence, intensity and /sup 13/C-/sup 13/C multiplet analysis allows quantitation of the pathways involved. Although blockage of the Krebs cycle at the ..cap alpha..-ketoglutarate dehydrogenase step is the basis for the accumulation of glutamate, significant Krebs cycle activity was found in glucose grown cells, and extensive Krebs cycle activity in cells metabolizing (1-/sup 13/C) acetate. In addition to the observation of the expected metabolites, the disaccharide ..cap alpha..,..cap alpha..-trehalose and ..cap alpha..,..beta..-glucosylamine were identified from the /sup 13/C NMR spectra.

  12. Comparative carbon-13, nitrogen-15, and phosphorus-31 nuclear magnetic resonance study on the flavodoxins from Clostridium MP, Megasphaera elsdenii, and Azotobacter vinelandii

    SciTech Connect

    Vervoort, J.; Mueller, F.; Mayhew, S.G.; van den Berg, W.A.M.; Moonen, C.T.W.; Bacher, A.

    1986-11-04

    The flavodoxins from Megasphaera elsdenii, Clostridium MP, and Azotobacter vinelandii were studied by /sup 13/C, /sup 15/N, and /sup 31/P NMR techniques by using various selectivity enriched oxidized riboflavin 5'-phosphate (FMN) derivatives. It is shown that the ..pi.. electron distribution in protein-bound flavin differs from that of free flavin and depends also on the apoflavoprotein used. In the oxidized state Clostridium MP and M. elsdenii flavodoxins are very similar with respect to specific hydrogen bond interaction between FMN and the apoprotein and the electronic structure of flavin. A vinelandii flavodoxin differs from these flavodoxins in both respects, but it also differs from Desulfovibrio vulgaris flavodoxin. The similarities between A. vinelandii and D. vulgaris flavodoxins are greater than the similarities with the other two flavodoxins. The differences in the ..pi.. electron distribution in the FMN of reduced flavodoxins from A. vinelandii and D. vulgaris are even greater, but the hydrogen bond patterns between the reduced flavins and the apoflavodoxins are very similar. In the reduced state all flavodoxins studied contain an ionized prosthetic group and the isoalloxazine ring is in a planar conformation. The results are compared with existing three-dimensional data and discussed with respect to the various possible mesomeric structures in protein-bound FMN. The results are discussed in light of the proposed hypothesis that specific hydrogen bonding to the protein-bound flavin determines the specific biological activity of a particular flavoprotein.

  13. Spin noise spectroscopy in semiconductors: from a billion down to single spins

    NASA Astrophysics Data System (ADS)

    Hbner, J.; Dahbashi, R.; Berski, F.; Wiegand, J.; Kuhn, H.; Lonnemann, J.; Oestreich, M.

    2014-08-01

    Spin noise spectroscopy in semiconductors has matured during the past nine years into a versatile and well developed technique being capable to unveil the intrinsic and unaltered spin dynamics in a wide range of semiconductor systems. Originating from atom and quantum optics as a potential true quantum non-demolition measurement technique, SNS is capable of unearthing the intricate dynamics of free or localized electron and hole spins in semiconductors being eventually coupled to the nuclear spin bath as well. In this contribution, we review shortly the major steps which inspired the success of spin noise spectroscopy in semiconductors and present the most recent extensions into the low-invasive detection regime of the spin dynamics for the two extreme limits of very high and extremely low rates of spin decoherence, respectively. On the one hand, merging ultrafast laser spectroscopy with spin noise spectroscopy enables the detection of spin noise with picosecond resolution, i.e., with THz bandwidths yielding access to otherwise concealed microscopic electronic processes. On the other hand, we present very high sensitivity SNS being capable to measure the extremely long spin coherence of single holes enclosed in individual quantum dots venturing a step forward towards true optical quantum non-demolition experiments in semiconductors. In addition, higher-order spin noise statistics of, e.g., single charges can give information beyond the linear response regime governed by the fundamental fluctuationdissipation theorem and thereby possibly shed some light on the nested coupling between electronic and nuclear spins.

  14. Exploring the conformational energy landscape of glassy disaccharides by cross polarization magic angle spinning 13C nuclear magnetic resonance and numerical simulations. II. Enhanced molecular flexibility in amorphous trehalose

    NASA Astrophysics Data System (ADS)

    Lefort, Ronan; Bordat, Patrice; Cesaro, Attilio; Descamps, Marc

    2007-01-01

    This paper uses chemical shift surfaces to simulate experimental C13 cross polarization magic angle spinning spectra for amorphous solid state disaccharides, paying particular attention to the glycosidic linkage atoms in trehalose, sucrose, and lactose. The combination of molecular mechanics with density functional theory/gauge invariant atomic orbital ab initio methods provides reliable structural information on the conformational distribution in the glass. The results are interpreted in terms of an enhanced flexibility that trehalose possesses in the amorphous solid state, at least on the time scale of C13 nuclear magnetic resonance measurements. Implications of these findings for the fragility of trehalose glass and bioprotectant action are discussed.

  15. Spin-dependent recombination and hyperfine interaction at deep defects

    NASA Astrophysics Data System (ADS)

    Ivchenko, E. L.; Bakaleinikov, L. A.; Kalevich, V. K.

    2015-05-01

    We present a theoretical study of optical electron-spin orientation and spin-dependent Shockley-Read-Hall recombination in the longitudinal magnetic field, taking into account the hyperfine coupling between the bound-electron spin and the nuclear spin of a deep paramagnetic center. The master rate equations for the coupled system are extended to describe the nuclear spin relaxation by using two distinct relaxation times, τn 1 and τn 2, respectively, for defect states with one and two (singlet) bound electrons. The general theory is developed for an arbitrary value of the nuclear spin I . The magnetic-field and excitation-power dependencies of the electron and nuclear spin polarizations are calculated for the value of I =1 /2 . In this particular case the nuclear effects can be taken into account by a simple replacement of the bound-electron spin relaxation time by an effective time dependent on free-electron and hole densities and free-electron spin polarization. The role of nuclear spin relaxation is visualized by isolines of the electron spin polarization on a two-dimensional graph with the axes log2(τn 1) and log2(τn 2) .

  16. Spin and spin-isospin instabilities and Landau parameters of Skyrme interactions with tensor correlations

    SciTech Connect

    Cao Ligang; Colo, Gianluca; Sagawa, Hiroyuki

    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.

  17. Quantum spin coherence in halogen-modified Cr7Ni molecular nanomagnets

    NASA Astrophysics Data System (ADS)

    Kaminski, Danielle; Webber, Amy L.; Wedge, Christopher J.; Liu, Junjie; Timco, Grigore A.; Vitorica-Yrezabal, Iigo J.; McInnes, Eric J. L.; Winpenny, Richard E. P.; Ardavan, Arzhang

    2014-11-01

    Among the factors determining the quantum coherence of the spin in molecular magnets are the presence and the nature of nuclear spins in the molecule. We have explored modifying the nuclear-spin environment in Cr7Ni -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. 63Cu Nuclear Spin-Lattice Relaxation Study for Low-Temperature Structural Transition in (La1-xBax)2CuO4 around x{=}0.06

    NASA Astrophysics Data System (ADS)

    Tou, Hideki; Matsumura, Masahiro; Yamagata, Hideki

    1993-05-01

    The nuclear spin-lattice relaxation rate 1/T1 of 63Cu was measured in the range from 1.5 to 300 K for x{=}0.0625 and x{=}0.08 in (La1-xBax)2CuO4. In the high-temperature tetragonal (HTT) and the low-temperature orthorhombic (LTO) phases in the normal state, 1/T1T for both samples follows the Curie-Weiss law, C/(T+?), suggesting that the two-dimensional (2D) antiferromagnetic (AF) fluctuation among Cu spins is dominant, similarly to the (La1-xSrx)2CuO4 system. In the HTT and LTO phases, no significant differences except for a slight difference in ? were observed between the two samples. In the low-temperature tetragonal (LTT) phase for x{=}0.0625, 1/T1 diverges at about 35 K, confirming the existence of magnetic ordering. The magnetic ordering at the finite temprature suggedsts that the dominant 2D-AF correlation of Cu spins in the HTT or LTO phase becomes the 3D-AF correlation derived from the some interactions along the c axis in the LTT phase.

  19. Theoretical study of the nuclear spin-molecular rotation coupling for relativistic electrons and non-relativistic nuclei. II. Quantitative results in HX (X = H,F,Cl,Br,I) compounds.

    PubMed

    Aucar, I Agustín; Gómez, Sergio S; Melo, Juan I; Giribet, Claudia C; Ruiz de Azúa, Martín C

    2013-04-01

    In the present work, numerical results of the nuclear spin-rotation (SR) tensor in the series of compounds HX (X = H,F,Cl,Br,I) within relativistic 4-component expressions obtained by Aucar et al. [J. Chem. Phys. 136, 204119 (2012)] are presented. The SR tensors of both the H and X nuclei are discussed. Calculations were carried out within the relativistic Linear Response formalism at the Random Phase Approximation with the DIRAC program. For the halogen nucleus X, correlation effects on the non-relativistic values are shown to be of similar magnitude and opposite sign to relativistic effects. For the light H nucleus, by means of the linear response within the elimination of the small component approach it is shown that the whole relativistic effect is given by the spin-orbit operator combined with the Fermi contact operator. Comparison of "best estimate" calculated values with experimental results yield differences smaller than 2%-3% in all cases. The validity of "Flygare's relation" linking the SR tensor and the NMR nuclear magnetic shielding tensor in the present series of compounds is analyzed. PMID:23574208

  20. Spin Polarized Superfluid 3He A1

    NASA Astrophysics Data System (ADS)

    Kojima, Harry; Ishimoto, Hidehiko

    2008-11-01

    Under applied magnetic field, the originally single superfluid 3He transition near 3 mK in zero field splits into two transitions between which a new A1 phase emerges. The two second order transitions are marked by abrupt changes in viscosity, zero sound attenuation and nuclear magnetic resonance. To date, the maximum magnetic field for producing A1 phase is 15 T. The A1 phase has been identified with a spin-polarized (ferromagnetic) superfluid system which breaks the relative symmetry between spin, orbit and gauge spaces. A superfluid mass current in A1 is simultaneously a spin current resulting in the propagation of spin-entropy wave. Experiments with spin-entropy wave provide measurements of anisotropic superfluid density and strong coupling parameters, spin diffusion coefficient and texture transformations. Owing to the spin-polarized nature, superflows may be generated by applied magnetic field gradients and measured from the induced magnetic fountain pressure. The mechanical spin density detector is developed to measure the spin relaxation in A1 phase. The observed unexpected temperature dependence of the spin relaxation time gives evidence that the A1 phase contains a small amount of the predicted minority spin condensate from dipolar interaction energy.