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1

Carbon-13 and silicon-29 spin-lattice relaxation in phenylmethanes and phenylsilanes  

NASA Astrophysics Data System (ADS)

Carbon-13 and silicon-29 spin-lattice relaxation times and the corresponding nuclear Overhauser enhancements have been measured for PhnXH4-n (n = 1-4, X = C or Si). Thence dipolar and other contributions to the relaxation rate have been separated. The dipolar contribution is dominant, except for -CH3 and -SiH3 groups. Correlation times for overall molecular motion have been estimated, and T1 ratios for phenyl groups have been used to compare the rotational mobility of the phenyl groups. Internal molecular motion is more hindered in phenylmethanes than in phenylsilanes. Results for diphenylmethane and diphenylsilane are consistent with strong coupling between internal and overall molecular motion.

Harris, Robin K.; Newman, Roger H.

2

The first observation of Carbon-13 spin noise spectra  

PubMed Central

We demonstrate the first 13C NMR spin noise spectra obtained without any pulse excitation by direct detection of the randomly fluctuating noise from samples in a cryogenically cooled probe. Noise power spectra were obtained from 13C enriched methanol and glycerol samples at 176 MHz without and with 1H decoupling, which increases the sensitivity without introducing radio frequency interference with the weak spin noise. The multiplet amplitude ratios in 1H coupled spectra indicate that, although pure spin noise prevails in these spectra, the influence of absorbed circuit noise is still significant at the high concentrations used. In accordance with the theory heteronuclear Overhauser enhancements are absent from the 1H-decoupled 13C spin noise spectra. PMID:23041799

Schlagnitweit, Judith; Muller, Norbert

2012-01-01

3

Nuclear Molecular Orbital Effects and the Carbon -13 + CARBON13 ---> CARBON12 + CARBON14 Rearrangement Reaction  

Microsoft Academic Search

Collective molecular configurations are observed in nuclei, and of considerable current interest is whether nuclear systems also exhibit single-particle molecular orbital (MO) behavior. An investigation of a heavy-ion single-neutron transfer reaction was carried out for the specific purpose of providing new information concerning the details of the transfer process and to search for evidence of MO effects. The single-neutron transfer

Steven Kenneth Korotky

1980-01-01

4

Carbon-13 and proton nuclear magnetic resonance spectroscopy of water-soluble porphyrins and metalloporphyrins.  

PubMed

Carbon-13 and proton nuclear magnetic resonance (NMR) spectra have been recorded for porphyrins, zinc porphyrins, and iron(III) porphyrin complexes in aqueous media. Spectra of porphyrin-c and hemin-c confirm the structure with thioether linkages at positions alpha to the porphyrin ring. The pattern of NMR isotropic shifts has implications regarding electron transfer in cytochrome-c. Free-base porphyrin-c and meso-substituted porphyrins have been examined for pyrrole nitrogen-hydrogen tautomerism and possible aggregation in aqueous solution. Zinc porphyrin 13C NMR spectra were recorded in order to provide diamagnetic references for paramagnetic iron(III) derivatives. Low-spin iron(III) porphyrin-biscyano complexes in aqueous solution exhibit NMR isotropic shift patterns similar to those previously observed for related compounds in non-aqueous media. The first 13C NMR spectra are reported for mu-oxo-bridged iron(III) porphyrin dimers. A partially resolved spectrum of a high-spin iron(III) porphyrin has also been obtained. Patterns of 13C and proton isotropic shifts are compared, and unpaired spin delocalization mechanisms for 13C resonances are discussed in a qualitative manner. PMID:687673

Goff, H M; Morgan, L O

1978-07-01

5

Carbon-13 nuclear magnetic resonance analysis of formaldehyde free preservatives.  

PubMed

Preservation of biomolecules is pivotal in increasingly important molecular diagnostics. Traditionally, formaldehyde is employed for such biomolecular preservation in spite of its carcinogenicity. Moreover, formaldehyde induced cross-linking during fixation is reported to alter structural and functional properties of the preserved biomolecules. Therefore, formaldehyde-free preservatives are advantageous because they are safer for laboratory personnel and they protect the structural and functional integrity of the biomolecules. Streck Cell Preservative and Cell-Free DNA BCT reagents are used as formaldehyde alternative preservatives. However, no studies have been carried out to evaluate formaldehyde concentrations in these preservatives. In this study, we evaluated the free formaldehyde concentrations of these reagents by carbon-13 ((13)C) NMR spectroscopic analysis. Chemically non-invasive NMR analysis is more reliable than the traditional derivatization based techniques in formaldehyde detection. (13)C NMR technique can be used for quantitative measurement by using (13)C NMR-relaxation agents. In this manuscript, we report an optimized NMR analysis method using Gadolinium diethylenetriaminepentaacetate. Additionally the data reported herein provide spectral analyses that indicate Streck Cell Preservative and Cell-Free DNA BCT reagents do not contain detectable free formaldehyde. Therefore, these preservatives are safer alternatives than formaldehyde for laboratory use, which can protect the overall integrity of the biomolecules within preserved samples. PMID:23261251

Das, Kausik; Dumais, Joseph; Basiaga, Sara; Krzyzanowski, Gary D

2013-06-01

6

High resolution carbon-13 nuclear magnetic resonance spectrometry and relaxation behavior of organic solids from fossil fuels  

SciTech Connect

A wide range of simple organic solids of relevance to coal structure has been examined by cross polarisation carbon 13 nuclear magnetic resonance spectrometry. Spin-lattice relaxation times of protons (T/SUB/1(H)) small rigid molecules such as naphthalene anthracene and triphenylene are long, and these molecules are not observed under conditions normally used to obtain spectra of fossil fuels. However, the introduction of hydroaromatic rings into these molecules reduces T/SUB/1(H) to values more suitable for obtaining quantitative data for fossil fuels. Apparent carbon spin-spin relaxation times of fossil fuel derived compounds range from 14MU to 172 MU and can be used to identify and quantify protonated aromatic carbon in fossil fuels, provided the small rigid molecules discussed above are accounted for.

Wilson, M.A.

1984-03-01

7

Carbon-13 nuclear magnetic resonance studies of glycolysis in protozoa  

E-print Network

from substrate glucose was found to be incorporated without scrambling irto mannitol. Incu- bations with singly labeled glucoses confirmed this information. Path- ways of mannitol biosynthesis im Euglena gracilis z were found to in- volve a NADPH... OF CONTENTS ABSTRACT ACKNOWLEDGMENTS. TABLE OF CONTENTS. LIST OF TABLES LIST OF FIGURES. CHAPTER I. INTRODUCTION Nuclear Magnetic Resonance Spectroscopy. lh h t hit d E th E ~Et E itits CHAPTER II. EXPERIMENTAL. Growth and Harvest of Euglena gracilis...

Rhoades, Teresa Ann

2012-06-07

8

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

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.

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

1989-01-01

9

Studies of individual carbon sites of proteins in solution by natural abundance carbon 13 nuclear magnetic resonance spectroscopy. Relaxation behavior.  

PubMed

The aromatic regions in proton-decoupled natural abundance 13C Fourier transform nuclear magnetic resonance spectra (at 14.2 kG) of small native proteins contain broad methine carbon bands and narrow nonprotonated carbon resonances. Some factors that affect the use of natural abundance 13C Fourier transform NMR spectroscopy for monitoring individual nonprotonated aromatic carbon sites of native proteins in solution are discussed. The effect of protein size is evaluated by comparing the 13C NMR spectra of horse heart ferrocytochrome c, hen egg white lysozyme, horse carbon monoxide myoglobin, and human adult carbon monoxide hemoglobin. Numerous single carbon resonances are observed in the aromatic regions of 13C NMR spectra of cytochrome c, lysozyme, and myoglobin. The much larger hemoglobin yields few resolved individual carbon resonances. Theoretical and some experimental values are presented for the natural linewidths (W), spin-lattice relaxation times (T1), and nuclear Overhauser enhancements (NOE) of nonprotonated aromatic carbons and Czeta of arginine residues. In general, the 13C-1H dipolar mechanism dominates the relaxation of these carbons. 13C-14N dipolar relaxation contributes significantly to 1/T1 of C epsilon2 of tryptophan residues and Czeta of arginine residues of proteins in D2O. The NOE of each nonprotonated aromatic carbon is within experimental error of the calculated value of about 1.2. As a result, integrated intensities can be used for making a carbon count. Theoretical results are presented for the effect of internal rotation on W, T1, and the NOE. A comparison with the experimental T1 and NOE values indicates that if there is internal rotation of aromatic amino acid side chains, it is not fast relative to the over-all rotational motion of the protein. PMID:169239

Oldfield, E; Norton, R S; Allerhand, A

1975-08-25

10

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)

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.

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

11

Sensitive, quantitative carbon-13 NMR spectra by mechanical sample translation  

NASA Astrophysics Data System (ADS)

Collecting a truly quantitative carbon-13 spectrum is a time-consuming chore. Very long relaxation delays, required between transients to allow the z-magnetization, M z, of the spin with the longestT1 to return to the equilibrium value, M0, must precede each transient. These long delays also reduce sensitivity, as fewer transients per unit time can be acquired. In addition, sometimes T1 is not known to within even a factor of two: a conservative guess for the relaxation delay then leads to very low sensitivity. We demonstrate a fresh method to bypass these problems and collect quantitative carbon-13 spectra by swapping the sample volume after each acquisition with a different portion where the magnetization is already equilibrated to M0. Loading larger sample volumes of 10-20 mL into an unusually long (1520 mm) 5 mm OD. NMR tube and vertically sliding the tube between acquisitions accomplishes the swap. The relaxation delay can then be skipped altogether. The spectra are thus both quantitative, and far more sensitive. We demonstrate the moving tube technique on two small molecules (thymol and butylhydroxytoluene) and show good carbon-13 quantification. The gain in sensitivity can be as much as 10-fold for slowly-relaxing 13C resonances. These experiments show that quantitative, sensitive carbon-13 spectra are possible whenever sufficient sample volumes are available. The method is applicable to any slow-relaxing nuclear spin species, such as 29Si, 15N and other low-? nuclei.

Donovan, Kevin J.; Allen, Mary; Martin, Rachel W.; Shaka, A. J.

2009-04-01

12

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

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

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

1982-07-24

13

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)

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.

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

1984-01-01

14

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

PubMed

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

Pollock, J R; Goff, H M

1992-10-20

15

Sensitive, quantitative carbon-13 NMR spectra by mechanical sample translation.  

PubMed

Collecting a truly quantitative carbon-13 spectrum is a time-consuming chore. Very long relaxation delays, required between transients to allow the z-magnetization, M(z), of the spin with the longest T(1) to return to the equilibrium value, M(0), must precede each transient. These long delays also reduce sensitivity, as fewer transients per unit time can be acquired. In addition, sometimes T(1) is not known to within even a factor of two: a conservative guess for the relaxation delay then leads to very low sensitivity. We demonstrate a fresh method to bypass these problems and collect quantitative carbon-13 spectra by swapping the sample volume after each acquisition with a different portion where the magnetization is already equilibrated to M(0). Loading larger sample volumes of 10-20 mL into an unusually long (1520 mm) 5 mm OD. NMR tube and vertically sliding the tube between acquisitions accomplishes the swap. The relaxation delay can then be skipped altogether. The spectra are thus both quantitative, and far more sensitive. We demonstrate the moving tube technique on two small molecules (thymol and butylhydroxytoluene) and show good carbon-13 quantification. The gain in sensitivity can be as much as 10-fold for slowly-relaxing (13)C resonances. These experiments show that quantitative, sensitive carbon-13 spectra are possible whenever sufficient sample volumes are available. The method is applicable to any slow-relaxing nuclear spin species, such as (29)Si, (15)N and other low-gamma nuclei. PMID:19179097

Donovan, Kevin J; Allen, Mary; Martin, Rachel W; Shaka, A J

2009-04-01

16

Transport, Compartmentation, and Metabolism of Homoserine in Higher Plant Cells . Carbon13- and Phosphorus31Nuclear Magnetic Resonance Studies  

Microsoft Academic Search

The transport, compartmentation, and metabolism of homoserine was characterized in two strains of meristematic higher plant cells, the dicotyledonous sycamore (Acer pseudoplatanus) and the mono- cotyledonous weed Echinochloa colonum. Homoserine is an inter- mediate in the synthesis of the aspartate-derived amino acids me- thionine, threonine (Thr), and isoleucine. Using 13C-nuclear magnetic resonance, we showed that homoserine actively entered the cells

Serge Aubert; Gilles Curien; Richard Bligny; Elisabeth Gout; Roland Douce

1998-01-01

17

A carbon-13 nuclear magnetic resonance spectroscopic study of inter-proton pair order parameters: a new approach to study order and dynamics in phospholipid membrane systems.  

PubMed Central

We report a simple new nuclear magnetic resonance (NMR) spectroscopic method to investigate order and dynamics in phospholipids in which inter-proton pair order parameters are derived by using high resolution 13C cross-polarization/magic angle spinning (CP/MAS) NMR combined with 1H dipolar echo preparation. The resulting two-dimensional NMR spectra permit determination of the motionally averaged interpair second moment for protons attached to each resolved 13C site, from which the corresponding interpair order parameters can be deducted. A spin-lock mixing pulse before cross-polarization enables the detection of spin diffusion amongst the different regions of the lipid molecules. The method was applied to a variety of model membrane systems, including 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC)/sterol and 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC)/sterol model membranes. The results agree well with previous studies using specifically deuterium labeled or predeuterated phospholipid molecules. It was also found that efficient spin diffusion takes place within the phospholipid acyl chains, and between the glycerol backbone and choline headgroup of these molecules. The experiment was also applied to biosynthetically 13C-labeled ergosterol incorporated into phosphatidylcholine bilayers. These results indicate highly restricted motions of both the sterol nucleus and the aliphatic side chain, and efficient spin exchange between these structurally dissimilar regions of the sterol molecule. Finally, studies were carried out in the lamellar liquid crystalline (L alpha) and inverted hexagonal (HII) phases of 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE). These results indicated that phosphatidylethanolamine lamellar phases are more ordered than the equivalent phases of phosphatidylcholines. In the HII (inverted hexagonal) phase, despite the increased translational freedom, there is highly constrained packing of the lipid molecules, particularly in the acyl chain region. PMID:9726938

Urbina, J A; Moreno, B; Arnold, W; Taron, C H; Orlean, P; Oldfield, E

1998-01-01

18

Conversion of Nuclear Spin Isomers of Ethylene  

NASA Astrophysics Data System (ADS)

A theoretical model of the nuclear spin isomer conversion in C2H4 induced by the intramolecular spin-spin interaction between hydrogen nuclei has been developed. In the ground electronic state, C2H4 has four nuclear spin isomers in contrast to two isomers in the molecules studied so far in this field of research. At the gas pressure of 1 Torr, the rate of conversion between isomers with the nuclear spin symmetries B1u and B2u was found to be 5.2 - 10-4 s-1, which coincides within experimental uncertainties with the rate recently measured by Sun et al. ( Science 2005, 310, 1938 ). It was determined that at low gas pressures the conversion is induced mainly by the mixing of only one pair of rotational states. The calculated pressure dependence of the conversion rate predicts that conversion slows down with increasing pressure at pressures higher than 300 Torr.

Chapovsky, P. L.; Zhivonitko, V. V.; Koptyug, I. V.

2013-10-01

19

Nuclear spin conversion in diatomic molecules  

SciTech Connect

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})

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

2013-07-15

20

Liquid-state nuclear spin comagnetometers.  

PubMed

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 5×10(-9)??Hz, or about 5×10(-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

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

2012-06-15

21

Decoherence of nuclear spin quantum memory in a quantum dot  

Microsoft Academic Search

Recently, an ensemble of nuclear spins in a quantum dot have been proposed as a long-lived quantum memory. A quantum state of an electron spin in the dot can be faithfully transfered into nuclear spins through controlled hyperfine coupling. Here we study the decoherence of this memory due to nuclear spin dipolar coupling and inhomogeneous hyperfine interaction during the storage

Changxue Deng; Xuedong Hu

2005-01-01

22

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

E-print Network

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

Clarice D. Aiello; Paola Cappellaro

2014-10-21

23

Optical switching of nuclear spin-spin couplings in semiconductors  

PubMed Central

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

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

2011-01-01

24

Nuclear moment of inertia and spin distribution of nuclear levels  

SciTech Connect

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.

Alhassid, Y.; Fang, L.; Liu, S. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Bertsch, G.F. [Department of Physics and Institute of Nuclear Theory, Box 351560, University of Washington Seattle, Washington 98915 (United States)

2005-12-15

25

Readout and control of a single nuclear spin with a metastable electron spin ancilla.  

PubMed

Electron and nuclear spins associated with point defects in insulators are promising systems for solid-state quantum technology. The electron spin is usually used for readout and addressing, and nuclear spins are used as exquisite quantum bits and memory systems. With these systems, single-shot readout of single nuclear spins as well as entanglement, aided by the electron spin, have been shown. Although the electron spin in this example is essential for readout, it usually limits the nuclear spin coherence, leading to a quest for defects with spin-free ground states. Here, we isolate a hitherto unidentified defect in diamond and use it at room temperature to demonstrate optical spin polarization and readout with exceptionally high contrast (up to 45%), coherent manipulation of an individual excited triplet state spin, and coherent nuclear spin manipulation using the triplet electron spin as a metastable ancilla. We demonstrate nuclear magnetic resonance and Rabi oscillations of the uncoupled nuclear spin in the spin-free electronic ground state. Our study demonstrates that nuclei coupled to single metastable electron spins are useful quantum systems with long memory times, in spite of electronic relaxation processes. PMID:23793305

Lee, Sang-Yun; Widmann, Matthias; Rendler, Torsten; Doherty, Marcus W; Babinec, Thomas M; Yang, Sen; Eyer, Moritz; Siyushev, Petr; Hausmann, Birgit J M; Loncar, Marko; Bodrog, Zoltán; Gali, Adam; Manson, Neil B; Fedder, Helmut; Wrachtrup, Jörg

2013-07-01

26

Electrically driven nuclear spin resonance in single-molecule magnets.  

PubMed

Recent advances in addressing isolated nuclear spins have opened up a path toward using nuclear-spin-based quantum bits. Local magnetic fields are normally used to coherently manipulate the state of the nuclear spin; however, electrical manipulation would allow for fast switching and spatially confined spin control. Here, we propose and demonstrate coherent single nuclear spin manipulation using electric fields only. Because there is no direct coupling between the spin and the electric field, we make use of the hyperfine Stark effect as a magnetic field transducer at the atomic level. This quantum-mechanical process is present in all nuclear spin systems, such as phosphorus or bismuth atoms in silicon, and offers a general route toward the electrical control of nuclear-spin-based devices. PMID:24904159

Thiele, Stefan; Balestro, Franck; Ballou, Rafik; Klyatskaya, Svetlana; Ruben, Mario; Wernsdorfer, Wolfgang

2014-06-01

27

NUCLEAR SPIN ISOSPIN RESPONSES FOR LOW-ENERGY NEUTRINOS  

E-print Network

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

Washington at Seattle, University of

28

Electronic transport through nuclear-spin-polarization-induced quantum wire  

E-print Network

Electron transport in a new low-dimensional structure - the nuclear spin polarization induced quantum wire (NSPI QW) is theoretically studied. In the proposed system the local nuclear spin polarization creates the effective hyperfine field which confines the electrons with the spins opposite to the hyperfine field to the regions of maximal nuclear spin polarization. The influence of the nuclear spin relaxation and diffusion on the electron energy spectrum and on the conductance of the quantum wire is calculated and the experimental feasibility is discussed.

Yu. V. Pershin; S. N. Shevchenko; I. D. Vagner; P. Wyder

2001-09-25

29

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

30

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

PubMed Central

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

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

2014-01-01

31

Spin phase coherence of donor nuclear spins in silicon: the influence of electrical readout  

NASA Astrophysics Data System (ADS)

Storing information in spin underpins the operation of a wide range of emerging technologies. However, the ability to interact with, and thus control electron spin implies a reasonable coupling to the environment, and a correspondingly limited spin coherence time. This problem can be overcome by using nuclear spins for long term information storage, and significant experimental progress in this direction has been seen recently. Readout of stored information can be achieved in a variety of ways, with electrical approaches offering substantial benefit with regard to integration of spintronic and classical electronic applications. Here, we discuss electrical readout of coherent nuclear spin states of donor nuclei in silicon. By utilizing nuclear Hahn echo sequences, we are able to demonstrate that nuclear spin phase coherence can exceed 3 ms with electrical readout. We find that the spin phase coherence is in this case limited by the spin lifetime of the donor electron which mediates our readout scheme, and discuss approaches to ameliorate this effect.

McCamey, Dane; van Tol, Johan; Morley, Gavin; Boehme, Christoph

2012-02-01

32

Dynamic Nuclear Spin Resonance in n-GaAs  

NASA Astrophysics Data System (ADS)

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.

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

2011-10-01

33

Dynamic nuclear spin resonance in n-GaAs.  

PubMed

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

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

2011-10-14

34

A method for nuclear spin statistics in molecular spectroscopy  

Microsoft Academic Search

Using spin projection operator methods, generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible respresentations spanned by a1b1a2b2???atbt nuclear spin functions, where ai is the number of possible spin states of the bi nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any

K. Balasubramanian

1981-01-01

35

Adiabatic refocusing of nuclear spins in Tm3+:YAG  

E-print Network

We show that the optical absorbance detection of nuclear spin echo gives direct access to the spin concentration, unlike most coherent signal detection techniques where the signal intensity/amplitude is difficult to connect experimentally with the spin concentration. This way we measure the spin refocusing efficiency in a crystal of Tm$^{3+}$:YAG. Given the large inhomogeneous broadening of the spin transition in this material, rephasing the spins with the usual hard pulse procedure would require excessively high radiofrequency power. Instead we resort to an adiabatic pulse sequence that perfectly returns the spins to their initial common orientation, at low power cost.

Lauro, R; Gouet, J -L Le

2010-01-01

36

Adiabatic refocusing of nuclear spins in Tm3+:YAG  

E-print Network

We show that the optical absorbance detection of nuclear spin echo gives direct access to the spin concentration, unlike most coherent signal detection techniques where the signal intensity/amplitude is difficult to connect experimentally with the spin concentration. This way we measure the spin refocusing efficiency in a crystal of Tm$^{3+}$:YAG. Given the large inhomogeneous broadening of the spin transition in this material, rephasing the spins with the usual hard pulse procedure would require excessively high radiofrequency power. Instead we resort to an adiabatic pulse sequence that perfectly returns the spins to their initial common orientation, at low power cost.

R. Lauro; T. Chaneliere; J. -L. Le Gouet

2010-09-22

37

Adiabatic refocusing of nuclear spins in Tm3+:YAG  

NASA Astrophysics Data System (ADS)

We show that the optical absorbance detection of nuclear spin echo gives direct access to the spin concentration, unlike most coherent signal detection techniques where the signal intensity/amplitude is difficult to connect experimentally with the spin concentration. This way we measure the spin-refocusing efficiency in a crystal of Tm3+:YAG. Given the large inhomogeneous broadening of the spin transition in this material, rephasing the spins with the usual hard pulse procedure would require excessively high radiofrequency power. Instead we resort to an adiabatic pulse sequence that perfectly returns the spins to their initial common orientation, at low power cost.

Lauro, R.; Chanelière, T.; Le Gouët, J.-L.

2011-01-01

38

Coherence and control of quantum registers based on electronic spin in a nuclear spin bath.  

PubMed

We consider a protocol for the control of few-qubit registers comprising one electronic spin embedded in a nuclear spin bath. We show how to isolate a few proximal nuclear spins from the rest of the bath and use them as building blocks for a potentially scalable quantum information processor. We describe how coherent control techniques based on magnetic resonance methods can be adapted to these solid-state spin systems, to provide not only efficient, high fidelity manipulation but also decoupling from the spin bath. As an example, we analyze feasible performances and practical limitations in the realistic setting of nitrogen-vacancy centers in diamond. PMID:19519089

Cappellaro, P; Jiang, L; Hodges, J S; Lukin, M D

2009-05-29

39

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

NASA Technical Reports Server (NTRS)

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.

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

2004-01-01

40

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

E-print Network

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

Rosen, Matthew S

41

Squeezing and entangling nuclear spins in helium 3  

E-print Network

We present a realistic model for transferring the squeezing or the entanglement of optical field modes to the collective ground state nuclear spin of $^3$He using metastability exchange collisions. We discuss in detail the requirements for obtaining good quantum state transfer efficiency and study the possibility to readout the nuclear spin state optically.

Gael Reinaudi; Alice Sinatra; Aurelien Dantan; Michel Pinard

2005-12-21

42

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

E-print Network

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

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

2014-04-10

43

Protection of centre spin coherence by dynamic nuclear spin polarization in diamond.  

PubMed

We experimentally investigate the protection of electron spin coherence of a nitrogen-vacancy (NV) centre in diamond by dynamic nuclear spin polarization (DNP). The electron spin decoherence of an NV centre is caused by the magnetic field fluctuation of the (13)C nuclear spin bath, which contributes large thermal fluctuation to the centre electron spin when it is in an equilibrium state at room temperature. To address this issue, we continuously transfer the angular momentum from electron spin to nuclear spins, and pump the nuclear spin bath to a polarized state under the Hartmann-Hahn condition. The bath polarization effect is verified by the observation of prolongation of the electron spin coherence time (T). Optimal conditions for the DNP process, including the pumping pulse duration and repeat numbers, are proposed by numerical simulation and confirmed by experiment. We also studied the depolarization effect of laser pulses. Our results provide a new route for quantum information processing and quantum simulation using the polarized nuclear spin bath. PMID:25042514

Liu, Gang-Qin; Jiang, Qian-Qing; Chang, Yan-Chun; Liu, Dong-Qi; Li, Wu-Xia; Gu, Chang-Zhi; Po, Hoi Chun; Zhang, Wen-Xian; Zhao, Nan; Pan, Xin-Yu

2014-09-01

44

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

NASA Astrophysics Data System (ADS)

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.[4pt] Reference:[0pt] ``Electronic read-out of a single nuclear spin using a molecular spin transistor,'' R. Vincent, S. Klyatskaya, M. Ruben, W. Wernsdorfer, F. Balestro, Nature, Vol. 488, p.357, (2012).

Balestro, Franck

2013-03-01

45

Nuclear spin diffusion effects in optically pumped quantum wells  

NASA Astrophysics Data System (ADS)

We studied the influence of the nuclear spin diffusion on the dynamical nuclear polarization of low dimensional nanostructures subject to optical pumping. Our analysis shows that the induced nuclear spin polarization in semiconductor nanostructures will develop both a time and position dependence due to a nonuniform hyperfine interaction as a result of the geometrical confinement provided by the system. In particular, for the case of semiconductor quantum wells, nuclear spin diffusion is responsible for a nonzero nuclear spin polarization in the quantum well barriers. As an example we considered a 57 Å GaAs square quantum well and a 1000 Å AlxGa1-xAs parabolic quantum well both within 500 Å Al0.4Ga0.6As barriers. We found that the average nuclear spin polarization in the quantum well barriers depends on the strength of the geometrical confinement provided by the structure and is characterized by a saturation time of the order of few hundred seconds. Depending on the value of the nuclear spin diffusion constant, the average nuclear spin polarization in the quantum well barriers can get as high as 70% for the square quantum well and 40% for the parabolic quantum well. These results should be relevant for both time resolved Faraday rotation and optical nuclear magnetic resonance experimental techniques.

Henriksen, Daniel; Kim, Tom; ?ifrea, Ionel

2014-01-01

46

Preparation of Nuclear Spin Singlet States Using Spin-Lock Induced Crossing  

NASA Astrophysics Data System (ADS)

We introduce a broadly applicable technique to create nuclear spin singlet states in organic molecules and other many-atom systems. We employ a novel pulse sequence to produce a spin-lock induced crossing (SLIC) of the spin singlet and triplet energy levels, which enables triplet-singlet polarization transfer and singlet-state preparation. We demonstrate the utility of the SLIC method by producing a long-lived nuclear spin singlet state on two strongly coupled proton pairs in the tripeptide molecule phenylalanine-glycine-glycine dissolved in D2O and by using SLIC to measure the J couplings, chemical shift differences, and singlet lifetimes of the proton pairs. We show that SLIC is more efficient at creating nearly equivalent nuclear spin singlet states than previous pulse sequence techniques, especially when triplet-singlet polarization transfer occurs on the same time scale as spin-lattice relaxation.

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

2013-10-01

47

Preparation of Nuclear Spin Singlet States using Spin-Lock Induced Crossing  

E-print Network

We introduce a broadly applicable technique to create nuclear spin singlet states in organic molecules and other many-atom systems. We employ a novel pulse sequence to produce a spin-lock induced crossing (SLIC) of the spin singlet and triplet energy levels, which enables triplet/singlet polarization transfer and singlet state preparation. We demonstrate the utility of the SLIC method by producing a long-lived nuclear spin singlet state on two strongly-coupled proton pairs in the tripeptide molecule phenylalanine-glycine-glycine dissolved in D2O, and by using SLIC to measure the J-couplings, chemical shift differences, and singlet lifetimes of the proton pairs. We show that SLIC is more efficient at creating nearly-equivalent nuclear spin singlet states than previous pulse sequence techniques, especially when triplet/singlet polarization transfer occurs on the same timescale as spin-lattice relaxation.

DeVience, Stephen J; Rosen, Matthew S

2013-01-01

48

Room temperature hyperpolarization of nuclear spins in bulk.  

PubMed

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 (1)H 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 (1)H 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 mm(3)) containing >10(19) (1)H 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

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

2014-05-27

49

Anomalous organic magnetoresistance from competing carrier-spin-dependent interactions with localized electronic and nuclear spins  

NASA Astrophysics Data System (ADS)

We describe a regime for low-field magnetoresistance in organic semiconductors, in which the spin-relaxing effects of localized nuclear spins and electronic spins interfere. The regime is studied by the controlled addition of localized electronic spins to a material that exhibits substantial room-temperature magnetoresistance (˜20%). Although initially the magnetoresistance is suppressed by the doping, at intermediate doping there is a regime where the magnetoresistance is insensitive to the doping level. For much greater doping concentrations the magnetoresistance is fully suppressed. The behavior is described within a theoretical model describing the effect of carrier spin dynamics on the current.

Wang, Y.; Harmon, N. J.; Sahin-Tiras, K.; Wohlgenannt, M.; Flatté, M. E.

2014-08-01

50

A method for nuclear spin statistics in molecular spectroscopy  

NASA Astrophysics Data System (ADS)

Using spin projection operator methods, generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible respresentations spanned by a1b1 a2b2???atbt nuclear spin functions, where ai is the number of possible spin states of the bi nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any polyatomic molecule can be obtained easily. The method is illustrated with 33SF6, 13C-triphenylene, and triphenylene with protons replaced by D. For 13C-triphenylene there are 1 073 741 824 nuclear spin functions from which we determined the statistical weights of the rovibronic levels A'1, A'2, E', A?1, A?2, and E? to be 178 940 928, 178 973 696, 357 913 600, 178 940 928, 178 973 696, and 357 913 600, respectively.

Balasubramanian, K.

1981-06-01

51

Single-shot readout of a single nuclear spin.  

PubMed

Projective measurement of single electron and nuclear spins has evolved from a gedanken experiment to a problem relevant for applications in atomic-scale technologies like quantum computing. Although several approaches allow for detection of a spin of single atoms and molecules, multiple repetitions of the experiment that are usually required for achieving a detectable signal obscure the intrinsic quantum nature of the spin's behavior. We demonstrated single-shot, projective measurement of a single nuclear spin in diamond using a quantum nondemolition measurement scheme, which allows real-time observation of an individual nuclear spin's state in a room-temperature solid. Such an ideal measurement is crucial for realization of, for example, quantum error correction protocols in a quantum register. PMID:20595582

Neumann, Philipp; Beck, Johannes; Steiner, Matthias; Rempp, Florian; Fedder, Helmut; Hemmer, Philip R; Wrachtrup, Jörg; Jelezko, Fedor

2010-07-30

52

Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics  

E-print Network

Pulsed Nuclear Magnetic Resonance: Spin Echoes MIT Department of Physics (Dated: February 5, 2014) In this experiment, the phenomenon of Nuclear Magnetic Resonance (NMR) is used to determine the magnetic moments-factor in atomic spectroscopy and is given by g = (µ/µN )/I, (2) and µN is the nuclear magneton, e /2mp

Seager, Sara

53

Spin-Orbit Interaction of Nuclear Shell Structure  

E-print Network

Single particle spin-orbit interaction energy problem in nuclear shell structure is solved through negative harmonic oscillator in the self-similar-structure shell model (SSM) [4] and considering quarks' contributions on single particle spin and orbit momentum. The paper demonstrates that single particle motion in normal nuclei is described better by SSM negative harmonic oscillator than conventional shell model positive harmonic oscillator[1][2][3]. The proposed theoretical formula for spin orbit interaction energy agrees well to experiment measurements.

Xiaobin Wang; Zhengda Wang; Xiaochun Wang; Xiaodong Zhang

2012-02-29

54

Polarization of nuclear spins by a cold nanoscale resonator  

SciTech Connect

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

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

2011-12-15

55

Polarization of nuclear spins by a cold nanoscale resonator  

NASA Astrophysics Data System (ADS)

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.

Butler, Mark C.; Weitekamp, Daniel P.

2011-12-01

56

Phase-sensitive probes of nuclear polarization in spin-blockaded transport  

E-print Network

Spin-blockaded quantum dots provide a unique setting for studying nuclear-spin dynamics in a nanoscale system. Despite recent experimental progress, observing phase-sensitive phenomena in nuclear spin dynamics remains ...

Levitov, Leonid

57

Electron spin dephasing and optical pumping of nuclear spins in GaN  

NASA Astrophysics Data System (ADS)

We have measured the donor-bound electron spin dynamics in cubic GaN by time-resolved Kerr rotation experiments. The ensemble electron spin dephasing time in this quantum-dot-like system characterized by a Bohr radius of 2.5 nm is of the order of 1.5 ns as a result of the interaction with the fluctuating nuclear spins. It increases drastically when an external magnetic field as small as 10 mT is applied. We extract a dispersion of the nuclear hyperfine field ?Bn˜4mT , in agreement with calculations. We also demonstrate for the first time in GaN-based systems the optical pumping of nuclear spin yielding the buildup of a significant nuclear polarization.

Wang, G.; Zhu, C. R.; Liu, B. L.; Ye, H.; Balocchi, A.; Amand, T.; Urbaszek, B.; Yang, H.; Marie, X.

2014-09-01

58

Quantum description of nuclear spin cooling in a quantum dot  

NASA Astrophysics Data System (ADS)

We study theoretically the cooling of an ensemble of nuclear spins coupled to the spin of a localized electron in a quantum dot. We obtain a master equation for the state of the nuclear spins interacting with a sequence of polarized electrons that allows us to study quantitatively the cooling process including the effect of nuclear spin coherences, which can lead to “dark states” of the nuclear system in which further cooling is inhibited. We show that the inhomogeneous Knight field mitigates this effect strongly and that the remaining dark-state limitations can be overcome by very few shifts of the electron wave function, allowing for cooling far beyond the dark-state limit. Numerical integration of the master equation indicates that polarizations larger than 90% can be achieved within a millisecond time scale.

Christ, H.; Cirac, J. I.; Giedke, G.

2007-04-01

59

Nuclear magnetic resonance spectroscopy with single spin sensitivity  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

60

Nuclear Spins in a Nanoscale Device for Quantum Information Processing  

E-print Network

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

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

2006-12-29

61

Nuclear spin qubits in a trapped-ion quantum computer  

E-print Network

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

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

2009-04-26

62

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

NASA Astrophysics Data System (ADS)

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.

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

2014-03-01

63

Nuclear spin-induced Cotton-Mouton effect in molecules.  

PubMed

In nuclear magneto-optic spectroscopy, effects of nuclear magnetization are detected in light passing through a sample containing spin-polarized nuclei. An optical analogue of nuclear magnetic resonance (NMR) chemical shift has been predicted and observed in the nuclear spin optical rotation of linearly polarized light propagating parallel to the nuclear magnetization. A recently proposed magneto-optic analogue of the NMR spin-spin coupling, the nuclear spin-induced Cotton-Mouton (NSCM) effect entails an ellipticity induced to linearly polarized light when passing through a medium with the nuclear spins polarized in a direction perpendicular to the light beam. Here we present a first-principles electronic structure formulation of NSCM in terms of response theory as well as ab initio and density-functional theory calculations for small molecules. The roles of basis set (we use completeness-optimized sets), electron correlation, and relativistic effects are discussed. It is found that the explicitly temperature-dependent contribution to NSCM, arising from the partial orientation of the molecules due to the nuclear magnetization, typically dominates the effect. This part of NSCM is proportional to the tensor product of molecular polarizability and the NMR direct dipolar coupling tensor. Hence, NSCM provides a means of investigating the dipolar coupling and, thus, molecular structure in a formally isotropic medium. Overall ellipticities of the order of magnitude of 10(-8)...10(-7) rad/(M cm) are predicted for fully polarized nuclei. These should be detectable with modern instrumentation in the Voigt setup. PMID:23742457

Fu, Li-juan; Vaara, Juha

2013-05-28

64

Electron and nuclear spins in semiconductor quantum dots  

NASA Astrophysics Data System (ADS)

The electron and nuclear spin degrees of freedom in two-dimensional semiconductor quantum dots are studied as important resources for such fields as spintronics and quantum information. The coupling of electron spins to their orbital motion, via the spin-orbit interaction, and to nuclear spins, via the hyperfine interaction, are important for understanding spin-dynamics in quantum dot systems. This work is concerned with both of these interactions as they relate to two-dimensional semiconductor quantum dots. We first consider the spin-orbit interaction in many-electron quantum dots, studying its role in conductance fluctuations. We further explore the creation and destruction of spin-polarized currents by chaotic quantum dots in the strong spin-orbit limit, finding that even without magnetic fields or ferromagnets (i.e., with time reversal symmetry) such systems can produce large spin-polarizations in currents passing through a small number of open channels. We use a density matrix formalism for transport through quantum dots, allowing consideration of currents entangled between different leads, which we show can have larger fluctuations than currents which are not so entangled. Second, we consider the hyperfine interaction between electrons and approximately 106 nuclei in two-electron double quantum dots. The nuclei in each dot collectively form an effective magnetic field interacting with the electron spins. We show that a procedure originally explored with the intent to polarize the nuclei can also equalize the effective magnetic fields of the nuclei in the two quantum dots or, in other parameter regimes, can cause the effective magnetic fields to have large differences.

Krich, Jacob Jonathan

65

Imaging mesoscopic nuclear spin noise with a diamond magnetometer  

E-print Network

Magnetic Resonance Imaging (MRI) can characterize and discriminate among tissues using their diverse physical and biochemical properties. Unfortunately, submicrometer screening of biological specimens is presently not possible, mainly due to lack of detection sensitivity. Here we analyze the use of a nitrogen-vacancy center in diamond as a magnetic sensor for nanoscale nuclear spin imaging and spectroscopy. We examine the ability of such a sensor to probe the fluctuations of the "classical" dipolar field due to a large number of neighboring nuclear spins in a densely protonated sample. We identify detection protocols that appropriately take into account the quantum character of the sensor and find a signal-to-noise ratio compatible with realistic experimental parameters. Through various example calculations we illustrate different kinds of image contrast. In particular, we show how to exploit the comparatively long nuclear spin correlation times to reconstruct a local, high-resolution sample spectrum.

C. A. Meriles; L. Jiang; G. Goldstein; J. S. Hodges; J. R. Maze; M. D. Lukin; P. Cappellaro

2010-04-30

66

Tilted Foils Nuclear Spin Polarization at REX-ISOLDE  

E-print Network

This thesis will explain and summarize my work and involvement in experiments aimed at producing nuclear spin polarization of post-accelerated beams of ions with the tilted-foils technique at the REX-ISOLDE linear accelerator at CERN. Polarizing the nuclear spin of radioactive beams in particular may provide access to observables which may be difficult to obtain otherwise. Currently, the techniques commonly employed for nuclear spin polarization are restricted to specific nuclides and experimental measurement techniques. Tilted foils polarization may provide a new tool to extend the range of nuclides that can be polarized and the types of experiments that can be performed. The experiments rely not only on the production but also on the method to measure the degree of attained polarization. Two methods will be treated, based on particle scattering in Coulomb excitation that may be utilized for stable beams, and the $\\beta$-NMR that requires $\\beta$-decaying nuclei. The experimental setups and measurements will...

Törnqvist, Hans Toshihide

2013-08-08

67

Phenomenological study of decoherence in solid-state spin qubits due to nuclear spin diffusion  

NASA Astrophysics Data System (ADS)

We present a study of the prospects for coherence preservation in solid-state spin qubits using dynamical decoupling protocols. Recent experiments have provided the first demonstrations of multipulse dynamical decoupling sequences in this qubit system, but quantitative analyses of potential coherence improvements have been hampered by a lack of concrete knowledge of the relevant noise processes. We present calculations of qubit coherence under the application of arbitrary dynamical decoupling pulse sequences based on an experimentally validated semiclassical model. This phenomenological approach bundles the details of underlying noise processes into a single experimentally relevant noise power spectral density. Our results show that the dominant features of experimental measurements in a two-electron singlet-triplet spin qubit can be replicated using a 1/?2 noise power spectrum associated with nuclear spin flips in the host material. Beginning with this validation, we address the effects of nuclear programming, high-frequency nuclear spin dynamics, and other high-frequency classical noise sources, with conjectures supported by physical arguments and microscopic calculations where relevant. Our results provide expected performance bounds and identify diagnostic metrics that can be measured experimentally in order to better elucidate the underlying nuclear spin dynamics.

Biercuk, Michael J.; Bluhm, Hendrik

2011-06-01

68

Quantum Information Transport in Nuclear Spin Chains  

Microsoft Academic Search

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

Paola Cappellaro; David Cory

2007-01-01

69

Towards understanding global variability in ocean carbon-13  

Microsoft Academic Search

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

Alessandro Tagliabue; Laurent Bopp

2008-01-01

70

Dynamic nuclear polarization from current-induced electron spin polarization  

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

71

Method for nuclear spin statistics in molecular spectroscopy  

SciTech Connect

Using spin projection operator methods, generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible respresentations spanned by a/sub 1//sup b//sub 1/ a/sub 2//sup b//sub 2/xxxa/sub t//sup b//sub t/ nuclear spin functions, where a/sub i/ is the number of possible spin states of the b/sub i/ nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any polyatomic molecule can be obtained easily. The method is illustrated with /sup 33/SF/sub 6/, /sup 13/C-triphenylene, and triphenylene with protons replaced by D. For /sup 13/C-triphenylene there are 1 073 741 824 nuclear spin functions from which we determined the statistical weights of the rovibronic levels A/sup prime//sub 1/, A/sup prime//sub 2/, E', A/sup double-prime//sub 1/, A/sup double-prime//sub 2/, and E'' to be 178 940 928, 178 973 696, 357 913 600, 178 940 928, 178 973 696, and 357 913 600, respectively.

Balasubramanian, K.

1981-06-15

72

A METHOD FOR NUCLEAR SPIN STATISTICS IN MOLECULAR SPECTROSCOPY  

SciTech Connect

Using spin projection operator methods generating functions are developed for nuclear spin species. These operators also generate elegantly the irreducible representations spanned by a{sub 1}{sup b{sub 1}}, a{sub 2}{sup b{sub 2}} .... a{sub t}{sup b{sub t}} nuclear spin functions where a{sub i} is the number of possible spin states of the b{sub i} nuclei of the same kind in the molecule. From these generating functions the statistical weights of the rovibronic levels of any polyatomic molecule can be obtained easily. The method is illustrated with SF{sub 6}, C{sup 13}-Triphenylene and triphenylene with protons replaced by D. For C{sup 13}-Triphenylene there are 1073741824 nuclear spin functions from which we determine the statistical weights of the rovibronic levels A{sub 1}, A{sub 2}, E, A{sub 1}', A{sub 2}' and E' to be 178940928, 178973696, 357913600, 178940928, 178973696, and 357913600, respectively.

Balasubramanian, K.

1980-10-01

73

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

E-print Network

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

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

2012-01-06

74

Hole - Nuclear Spin Interaction in Semiconductor Quantum Dots  

NASA Astrophysics Data System (ADS)

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. Lemaître, 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)

Marie, Xavier

2010-03-01

75

Nuclear Spin Gyroscope Based on an Atomic Comagnetometer  

SciTech Connect

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.

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

2005-12-02

76

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

E-print Network

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

Yang, Jamie Chiaming

2008-01-01

77

Chemical Distinction by Nuclear Spin Optical Rotation Suvi Ikalainen  

E-print Network

surroundings of magnetic nuclei. Efficient first-principles calculations for isolated water, ethanol, in which the magnetic field due to spin- polarized nuclei causes the plane of polarization of an incident microscopic property, the dependence of optical polarizability on the nuclear magnetic moment, the laser

Romalis, Mike

78

Spins as qubits: Quantum information processing by nuclear magnetic resonance  

E-print Network

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

Suter, Dieter

79

Nuclear spin dynamics in parabolic quantum wells Ionel Tifrea* and Michael E. Flatte  

E-print Network

Nuclear spin dynamics in parabolic quantum wells Ionel T¸ifrea* and Michael E. Flatte´ Department March 2004 We present a detailed analytical and numerical analysis of the nuclear spin dynamics of the electronic wave function in small electric fields. The nuclear spin relaxation via the hyperfine interaction

Flatte, Michael E.

80

The qubit states decoherence in antiferromagnet-based nuclear spin model of quantum register  

E-print Network

This study deals with the further development of nuclear spin model of scalable quantum register, which presents the one-dimensional chain of the magnetic atoms with nuclear spins 1/2, substituting the basic atoms in the plate of nuclear spin-free easy-axis 3D antiferromagnet. The decoherence rates of one qubit state and entanglement state of two removed qubits and longitudinal relaxation rates are caused by the interaction of nuclear spins-qubits with virtual spin waves in antiferromagnet ground state were calculated. It was considered also one qubit adiabatic decoherence, is caused by the interaction of nuclear spin of quantum register with nuclear spins of randomly distributed isotopes, substituting the basic nuclear spin-free isotopes of antiferromagnet. We have considered finally encoded DFS (Decoherence-Free Subspaces) logical qubits are constructed on clusters of the four-physical qubits, given by the two states with zero total angular momentum.

A. A. Kokin; V. A. Kokin

2010-03-01

81

Observation of scalar nuclear spin–spin coupling in van der Waals complexes  

PubMed Central

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 10 mG 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.

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

2012-01-01

82

Search for an Atomic EDM with Optical-Coupling Nuclear Spin Oscillator  

NASA Astrophysics Data System (ADS)

We have constructed a nuclear spin oscillator of a new type, that employs a feedback scheme based on an optical spin detection and suceeding spin control by a transverse field application. This spin oscillator parallels the conventional spin maser in many points, but exhibits advantages and requirements that are different from those with the spin maser. By means of the optical-coupling nuclear spin oscillator, an experimental setup to search for an electric dipole moment (EDM) in a spin 1/2 diamagnetic atom 129Xe is being developed.

Asahi, K.; Uchida, M.; Yoshimi, A.; Inoue, T.; Hatakeyama, N.

2007-06-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2014-09-01

84

Fidelity of optically induced single-spin rotations in semiconductor quantum dots in the presence of nuclear spins  

NASA Astrophysics Data System (ADS)

We examine the influence of nuclear spins on the performance of optically induced rotations of single electron spins in semiconductor quantum dots. We consider Raman type optical transitions between electron spin states and take into account the additional effect of the Overhauser field. We calculate average fidelities of rotations around characteristic axes in the presence of nuclear spins analytically with perturbation theory up to second order in the Overhauser field. Moreover, we calculate the fidelity using numerical averaging over the nuclear field distribution, including arbitrary orders of the hyperfine interaction.

Hildmann, Julia; Burkard, Guido

2014-09-01

85

Room-temperature optical manipulation of nuclear spin polarization in GaAsN  

NASA Astrophysics Data System (ADS)

The effect of hyperfine interaction on the room-temperature defect-enabled spin filtering effect in GaAsN alloys is experimentally investigated and theoretically interpreted through a master equation approach based on the hyperfine and Zeeman interaction between electron and nuclear spin of the Gai2+ interstitial spin filtering defect. We show that the nuclear spin polarization of the gallium defect can be tuned through the optically induced spin polarization of conduction band electrons.

Sandoval-Santana, C.; Balocchi, A.; Amand, T.; Harmand, J. C.; Kunold, A.; Marie, X.

2014-09-01

86

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

E-print Network

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

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

2009-12-22

87

Nuclear spin relaxation due to random motion of vortex bundles  

SciTech Connect

The dependence of nuclear-spin-relaxation rate {ital T}{sub 1} on NMR resonant frequency for a layered superconducting sample has been analyzed theoretically. In the considered arrangement the Zeeman field has been applied in the plane of superconducting layers while the relaxation was due to interactions between the spin systems and moving flux bundles, created by the transport current flowing along superconducting layers. It has been found that the functional form of a dependence of spin-relaxation rate on the Zeeman field has two components, a Lorentzian and an oscillatory one. The characteristic rolloff frequency of the Lorentzian component depends on the pinning properties of the sample. The period of oscillations of the oscillatory component is of the order of the inverse of interaction time of flowing flux bundles with a probe nucleus. {copyright} {ital 1996 The American Physical Society.}

Ashkenazy, V.D. [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)] [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel); Jung, G. [Department of Physics, Ben Gurion University of the Negev, 84105 Beer-Sheva (Israel)] [Department of Physics, Ben Gurion University of the Negev, 84105 Beer-Sheva (Israel); [Institute Fizyki PAN, 02668 Warszawa (Poland); Shapiro, B.Y. [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel)] [Department of Physics, Bar-Ilan University, 52100, Ramat Gan (Israel); [Jack and Pearl Resnick Institute of Advanced Technology and the Center of Superconductivity, Bar-Ilan University, 52100, Ramat Gan (Israel)

1996-02-01

88

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

E-print Network

magnetic moment () The Bohr model of H atom electron Nucleus I I = n I An intrinsic property of the nucleus alter the alignment of this magnetization, causing the hydrogen nuclei to produce a rotating magnetic #12; Nuclear Magnetic Resonance (NMR) This technique observes signals from nuclear spins

Chen, Yang-Yuan

89

Nuclear spin circular dichroism in fullerenes: a computational study.  

PubMed

In the recently proposed phenomenon, nuclear spin-induced circular dichroism (NSCD), collective magnetisation of nuclei induces circular dichroism in a light beam passing through a molecular sample. Here we present the first computational predictions of NSCD for fullerenes C60 and C70. We show that the NSCD signal is nucleus-specific, like in NMR spectroscopy. Thus, NSCD may provide a new and promising, high-resolution observable for experimental identification of chemical compounds. PMID:25341745

Straka, Michal; St?pánek, Petr; Coriani, Sonia; Vaara, Juha

2014-11-01

90

Nuclear Spin Relaxation and the Collision Frequency in Dense Gases  

Microsoft Academic Search

The relation between nuclear spin-lattice relaxation (T1) measurements and the collision frequency in dense gases is discussed. It is shown that the density dependence of T1 in compressed H2 gas can be accounted for by assuming a hard-sphere potential model and evaluating the Enskog correction to the collision frequency in a dense fluid. This comparison represents the first direct test

R. G. Gordon; R. L. Armstrong; E. Tward

1968-01-01

91

Interlayer diffusion of nuclear spin polarization in ? =2/3 quantum Hall states  

NASA Astrophysics Data System (ADS)

At the spin transition point of ? =2/3 quantum Hall states, nuclear spins in a two-dimensional electron gas are polarized by an electric current. Using GaAs/AlGaAs double-quantum-well samples, we first observed the spatial diffusion of nuclear spin polarization between the two layers when the nuclear spin polarization is current induced in one layer. By numerical simulation, we estimated the diffusion constant of the nuclear spin polarization to be 15±7nm2/s.

Nguyen, Minh-Hai; Tsuda, Shibun; Terasawa, Daiju; Fukuda, Akira; Zheng, Yangdong; Sawada, Anju

2014-01-01

92

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

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

93

Solid effect in magic angle spinning dynamic nuclear polarization  

PubMed Central

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

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

2012-01-01

94

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

NASA Astrophysics Data System (ADS)

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

Yoshimi, A.; Asahi, K.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Tsuchiya, M.; Kagami, S.

2009-08-01

95

Stable Three-Axis Nuclear Spin Gyroscope in Diamond  

E-print Network

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

Ajoy, Ashok

2012-01-01

96

Stable Three-Axis Nuclear Spin Gyroscope in Diamond  

E-print Network

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

Ashok Ajoy; Paola Cappellaro

2012-05-07

97

Estimation of optical chemical shift in nuclear spin optical rotation  

NASA Astrophysics Data System (ADS)

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

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

2014-05-01

98

Spin Instability in Nuclear Matter and the Skyrme Interaction  

NASA Astrophysics Data System (ADS)

In the present work the problem of spin instability of nuclear matter with the Skyrme interaction is analyzed. The three-body part of the interaction is replaced by using a density dependent potential which is a modification to that given previously by Dabrowski. The symmetry energies are calculated and their rearrangement corrections. Good agreement is obtained with previous calculations.Translated AbstractSpininstabilität in Kernmaterie und Skyrme-WechselwirkungDie vorliegende Arbeit analysiert die Spininstabilität von Kernmaterie mit Skyrme-Wechselwirkung. Der Dreikörperanteil der Wechselwirkung ist durch ein dichteabhängiges Potential ersetzt. Die Symmetrieenergien und ihre Umordnungskorrekturen werden berechnet. Sie stimmen gut mit vorhergehenden Rechnungen überein.

Mansour, H. M. M.

99

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

PubMed

The water-endofullerene H2O@C60 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 H2O 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 H2O molecules is catalysed by (13)C nuclei present in the cages. PMID:24852537

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

2014-05-21

100

Line Broadening and Decoherence of Electron Spins in Phosphorus-Doped Silicon Due to Environmental 29^Si Nuclear Spins  

E-print Network

Phosphorus-doped silicon single crystals with 0.19 % <= f <= 99.2 %, where f is the concentration of 29^Si isotopes, are measured at 8 K using a pulsed electron spin resonance technique, thereby the effect of environmental 29^Si nuclear spins on the donor electron spin is systematically studied. The linewidth as a function of f shows a good agreement with theoretical analysis. We also report the phase memory time T_M of the donor electron spin dependent on both f and the crystal axis relative to the external magnetic field.

Eisuke Abe; Akira Fujimoto; Junichi Isoya; Satoshi Yamasaki; Kohei M. Itoh

2005-12-16

101

Dynamical decoupling design for identifying weakly coupled nuclear spins in a bath  

NASA Astrophysics Data System (ADS)

Identifying weakly coupled nuclear spins around single electron spins is a key step toward implementing quantum information processing using coupled electron-nuclei spin systems or sensing like single-spin nuclear magnetic resonance detection using diamond defect spins. Dynamical decoupling control of the center electron spin with periodic pulse sequences [e.g., the Carre-Purcell-Meiboom-Gill (CPMG) sequence] has been successfully used to identify single nuclear spins and to resolve structure of nuclear spin clusters. Here, we design a type of pulse sequence by replacing the repetition unit (a single ? pulse) of the CPMG sequence with a group of nonuniformly spaced ? pulses. Using the nitrogen-vacancy center system in diamond, we theoretically demonstrate that the designed pulse sequence improves the resolution of nuclear spin noise spectroscopy, and more information about the surrounding nuclear spins is extracted. The principle of dynamical decoupling design proposed in this paper is useful in many systems (e.g., defect spin qubit in solids, trapped ion, and superconducting qubit) for high-resolution noise spectroscopy.

Zhao, Nan; Wrachtrup, Jörg; Liu, Ren-Bao

2014-09-01

102

Antiferromagnet-based nuclear spin model of scalable quantum register with inhomogeneous magnetic field  

E-print Network

As a nuclear spin model of scalable quantum register, the one-dimensional chain of the magnetic atoms with nuclear spins 1/2 substituting the basic atoms in the plate of nuclear spin free easy-axis 3D antiferromagnet is considered. It is formulated the generalized antiferromagnet Hamiltonian in spin-wave approximation (low temperatures) considering the inhomogeneous external magnetic field, which is directed along the easy axis normally to plane of the plate and has a constant gradient along the nuclear spin chain. Assuming a weak gradient, the asymptotic expression for coefficients of unitary transformations to the diagonal form of antiferromagnet Hamiltonian is found. With this result the expression for indirect interspin coupling, which is due to hyperfine nuclear electron coupling in atoms and the virtual spin wave propagation in antiferromagnet ground state, was evaluated. It is shown that the inhomogeneous magnetic field essentially modifies the characteristics of indirect interspin coupling. The indirect interaction essentially grows and even oscillates in relation to the interspin distance when the local field value in the middle point of two considered nuclear spin is close to the critical field for quantum phase transition of spin-flop type in bulk antiferromagnet or close to antiferromagnetic resonance. Thus, the external magnetic field, its gradient, microwave frequency and power can play the role of control parameters for qubit states. Finally, the one and two qubit states decoherence and longitudinal relaxation rate are caused by the interaction of nuclear spins with virtual spin waves in antiferromagnet ground state are calculated.

A. A. Kokin; V. A. Kokin

2008-12-01

103

The Nuclear Structure of ERBIUM-154 at High Spins  

NASA Astrophysics Data System (ADS)

The nuclear structure of the ('154)Er nucleus at high spins has been studied by using a heavy-ion fusion -evaporation reaction with an enriched ('124)Te target and a ('34)S-ion beam of 170 Mev bombarding energy. De-excitation gamma rays were detected by using the gamma-gamma coincidence method. Discrete gamma-ray spectra and gamma energy-energy correlation map for the ('154)Er nucleus were obtained. Present results are compared with previous work as well as with theoretical calculations. A new decay scheme of ('154)Er are deduced from the present experiment. Besides the new levels with higher spins which have been identified in this new decay scheme, the present results clarify the discrepancies in the level ordering of the decay scheme among previous reports. However, the absence of correlated gamma transitions in the gamma energy-energy correlation map does not support the prediction of superdeformed shapes in the ('154)Er nucleus at high spins. Possible reasons for this are discussed.

Chen, Ching-Yun

104

High-spin nuclear structure studies with radioactive ion beams  

SciTech Connect

Two important developments in the sixties, namely the advent of heavy-ion accelerators and fabrication of Ge detectors, opened the way for the experimental studies of nuclear properties at high angular momentum. Addition of a new degree of freedom, namely spin, made it possible to observe such fascinating phenomena as occurrences and coexistence of a variety of novel shapes, rise, fall and occasionally rebirth of nuclear collectivity, and disappearance of pairing correlations. Today, with the promise of development of radioactive ion beams (RIB) and construction of the third-generation Ge-detection systems (GAMMASPHERE and EUROBALL), the authors are poised to explore new and equally fascinating phenomena that have been hitherto inaccessible. With the addition of yet another dimension, namely the isospin, they will be able to observe and verify predictions for exotic shapes as varied as rigid triaxiality, hyperdeformation and triaxial octupole shapes, or to investigate the T = 0 pairing correlations. In this paper, they shall review, separately for neutron-deficient and neutron-rich nuclei, these and a few other new high-spin physics opportunities that may be realized with RIB. Following this discussion, they shall present a list of the beam species, intensities and energies that are needed to fulfill these goals. The paper will conclude with a description of the experimental techniques and instrumentations that are required for these studies.

Baktash, C.

1992-12-31

105

Ultrafast entangling gates between nuclear spins using photo-excited triplet states  

E-print Network

The representation of information within the spins of electrons and nuclei has been powerful in the ongoing development of quantum computers. Although nuclear spins are advantageous as quantum bits (qubits) due to their long coherence lifetimes (exceeding seconds), they exhibit very slow spin interactions and have weak polarisation. A coupled electron spin can be used to polarise the nuclear spin and create fast single-qubit gates, however, the permanent presence of electron spins is a source of nuclear decoherence. Here we show how a transient electron spin, arising from the optically excited triplet state of C60, can be used to hyperpolarise, manipulate and measure two nearby nuclear spins. Implementing a scheme which uses the spinor nature of the electron, we performed an entangling gate in hundreds of nanoseconds: five orders of magnitude faster than the liquid-state J coupling. This approach can be widely applied to systems comprising an electron spin coupled to multiple nuclear spins, such as NV centres, while the successful use of a transient electron spin motivates the design of new molecules able to exploit photo-excited triplet states.

Vasileia Filidou; Stephanie Simmons; Steven D. Karlen; Feliciano Giustino; Harry L. Anderson; John J. L. Morton

2012-01-23

106

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

E-print Network

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

V. A. Bednyakov; F. Simkovic

2006-08-09

107

Manipulation of nuclear spin dynamics in n-GaAs using an on-chip microcoil  

NASA Astrophysics Data System (ADS)

We present an approach for electrically manipulating nuclear spins in n-GaAs using an on-chip microcoil. Optically injected spin-polarized electrons are used to generate a dynamic nuclear polarization via electron-nucleus hyperfine interaction with a characteristic time constant of ˜10 min. The saturated Overhauser field amplitude is on the order of several 10 mT and proportional to the spin polarization degree of the injected electrons. Applying an rf field resonant for the A75s nuclei, complete depolarization of A75s nuclear spins is observed.

Chen, Y. S.; Huang, J.; Ludwig, A.; Reuter, D.; Wieck, A. D.; Bacher, G.

2011-01-01

108

Nuclear spin selection rules in chemical reactions by angular momentum algebra  

E-print Network

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

Oka, Takeshi

109

Dephasing and relaxation of central hole spins by nuclear spin baths in InGaAs quantum dots: role of nuclear quadrupolar coupling  

NASA Astrophysics Data System (ADS)

Single electron or hole spins in III-V semiconductor quantum dots (QDs) are promising candidates for solid-state qubits. Their coherence properties are typically governed by the hyperfine coupling between these ``central'' electronic spins and the dense surrounding bath of lattice nuclear spins. Theoretically this is a challenging problem due to its many-body and strongly-correlated nature. Here we measure the spin dynamics of holes in InGaAs quantum dots by detecting their intrinsic, random spin fluctuations while in thermal equilibrium, which reveals the spin correlation time scales ?h and the functional form of bath-induced spin relaxation. In zero magnetic field, ?h is very long (˜400 ns) and decays exponentially, in marked contrast with recent theories. ?h increases to ˜5 ?s in small (100 G) longitudinal fields, and the spin dynamics evolve to a very slow ˜1/ln(t) decay [1]. We model the influence of nuclear quadrupolar coupling on spin dynamics in these strained QDs for both electrons and holes [2], and find a good agreement with experimental data when the quadrupolar coupling exceeds the hyperfine coupling strength. [1] Yan Li, N. Sinitsyn, et al., PRL 108, 186603 (2012). [2] N. Sinitsyn, Yan Li, et al., PRL 109, 166605 (2012).

Li, Yan; Sinitsyn, N. A.; Saxena, A.; Smith, D. L.; Reuter, D.; Wieck, A. D.; Yakovlev, D. R.; Manfred, B.; Crooker, S. A.

2013-03-01

110

Distinguishing between Nonorthogonal Quantum States of a Single Nuclear Spin  

NASA Astrophysics Data System (ADS)

An important task for quantum-information processing is optimal discrimination between two nonorthogonal quantum states, which until now has been realized only optically. Here, we present and compare experimental realizations of optimal quantum measurements for distinguishing between two nonorthogonal quantum states encoded in a single N14 nuclear spin at a nitrogen-vacancy defect in diamond. Implemented measurement schemes are the minimum-error measurement (known as Helstrom measurement), unambiguous state discrimination using a standard projective measurement, and optimal unambiguous state discrimination [known as Ivanovic-Dieks-Peres (IDP) measurement], which utilizes a three-dimensional Hilbert space. This allows us to benchmark the IDP measurement against the standard projective measurements. Measurement efficiencies are found to be above 80% for all schemes and reach a value of 90% for the IDP measurement.

Waldherr, Gerald; Dada, Adetunmise C.; Neumann, Philipp; Jelezko, Fedor; Andersson, Erika; Wrachtrup, Jörg

2012-11-01

111

Nuclear spin scissors - new type of collective motion  

NASA Astrophysics Data System (ADS)

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.

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

2014-09-01

112

Carbon-13 nuclear magnetic resonance characterization of network systems  

SciTech Connect

Solid-state C-13 NMR measurements are utilized to characterize the tetrafunctional epoxy, tetraglycidyl (diaminodiphenyl) methane, and the tetrafunctional amine, diaminodiphenyl sulfone. Intermolecular effective ether cross-links, amine junction points, and extent of reaction of the amine and epoxy are measured for the polymerization. Chemical reactions in the epoxy-amine system are discussed, and the reactivity ratio of the epoxy-amine system is calculated. Junction point measurements are made by the use of the dipolar dephasing relaxation experiment. The experimental data collected with C-13 NMR are then compared with the calculated data from a model developed in this laboratory. The information obtained in this study is sufficient to calculate the molecular weight between cross-links.

Mertzel, E.A.; Perchak, D.R.; Ritchey, W.M.; Koenig, J.L.

1988-04-01

113

Room-temperature solid-state quantum memory using pairs of nuclear spins in diamond  

NASA Astrophysics Data System (ADS)

We propose a robust, room-temperature solid-state quantum memory scheme using a pair of nuclear spin impurities in diamond. The memory qubit is encoded in a decoherence-free subspace of this nuclear spin pair, which protects it from noise originating from the surrounding environment. In addition, nuclear spins close to a Nitrogen-Vacancy (NV) color center experience a significant electron-mediated coupling, which further suppresses decoherence of the qubit. We obtain coherence times on the order of a second, along with fast manipulation and readout through the coupling of the nuclear spins to the NV electronic spin. We show that through engineering of the diamond sample this scheme could offer scalability to a many-qubit memory, and could be used as a basic building block for hybrid quantum networks and quantum computing architectures.

Bar-Gill, Nir; Devience, Stephen; Le Sage, David; Belthangady, Chinmay; Pham, Linh; Walsworth, Ronald

2012-02-01

114

Cooling a magnetic resonance force microscope via the dynamical back action of nuclear spins  

NASA Astrophysics Data System (ADS)

We analyze the back-action influence of nuclear spins on the motion of the cantilever of a magnetic force resonance microscope. We calculate the contribution of nuclear spins to the damping and frequency shift of the cantilever. We show that, at the Rabi frequency, the energy exchange between the cantilever and the spin system cools or heats the cantilever depending on the sign of the high-frequency detuning. We also show that the spin noise leads to a significant damping of the cantilever motion.

Greenberg, Ya. S.; Il'Ichev, E.; Nori, Franco

2009-12-01

115

Optical-coupling nuclear spin maser under highly stabilized low static field  

NASA Astrophysics Data System (ADS)

A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in 129Xe atom is being developed.

Yoshimi, A.; Inoue, T.; Uchida, M.; Hatakeyama, N.; Asahi, K.

2008-01-01

116

Optical-coupling nuclear spin maser under highly stabilized low static field  

NASA Astrophysics Data System (ADS)

A nuclear spin maser of a new type, that employs a feedback scheme based on optical nuclear spin detection, has been fabricated. The spin maser is operated at a low static field of 30 mG by using the optical detection method. The frequency stability and precision of the spin maser have been improved by a highly stabilized current source for the static magnetic field. An experimental setup to search for an electric dipole moment (EDM) in 129Xe atom is being developed.

Yoshimi, A.; Inoue, T.; Uchida, M.; Uatakeyama, N.; Asahi, K.

117

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

E-print Network

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

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

2004-09-12

118

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

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.

Ki Deok Park; Guo, K.; Adebodun, F.; Chiu, M.L.; Sligar, S.G.; Oldfield, E. (Univ. of Illinois, Urbana (United States))

1991-03-05

119

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

SciTech Connect

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

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

2013-12-04

120

Isotopically engineered silicon/silicon-germanium nanostructures as basic elements for a nuclear spin quantum computer  

NASA Astrophysics Data System (ADS)

The idea of quantum computation is the most promising recent development in the high-tech domain, while experimental realization of a quantum computer poses a formidable challenge. Among the proposed models especially attractive are semiconductor based nuclear spin quantum computers (S-NSQCs), where nuclear spins are used as quantum bistable elements, `qubits', coupled to the electron spin and orbital dynamics. We propose here a scheme for implementation of basic elements for S-NSQCs which are realizable within achievements of the modern nanotechnology. These elements are expected to be based on a nuclear-spin-controlled isotopically engineered Si/SiGe heterojunction, because in these semiconductors one can vary the abundance of nuclear spins by engineering the isotopic composition. A specific device is suggested, which allows one to model the processes of recording, reading and information transfer on a quantum level using the technique of electrical detection of the magnetic state of nuclear spins. Improvement of this technique for a semiconductor system with a relatively small number of nuclei might be applied to the manipulation of nuclear spin `qubits' in the future S-NSQCs.

Shlimak, I.; Safarov, V. I.; Vagner, I. D.

2001-07-01

121

Conditional Control of Donor Nuclear Spins in Silicon Using Stark Shifts  

NASA Astrophysics Data System (ADS)

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

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

2014-10-01

122

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

PubMed Central

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

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

2013-01-01

123

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

E-print Network

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 ...

Barnes, Alexander B.

124

Nuclear-Spin Gyroscope Based on an Atomic Co-Magnetometer  

NASA Technical Reports Server (NTRS)

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.

Romalis, Michael; Komack, Tom; Ghost, Rajat

2008-01-01

125

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

E-print Network

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

Romalis, Mike

126

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

SciTech Connect

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.

Afanasjev, A. V. [Mississippi State University/JIHIR, ORNL; Shi, Yue [Peking University; Nazarewicz, Witold [UTK/ORNL/University of Warsaw

2012-01-01

127

Search for electric dipole moment in 129Xe atom using active nuclear spin maser  

NASA Astrophysics Data System (ADS)

An experimental search for an electric dipole moment in the diamagnetic atom 129Xe is in progress through the precision measurement of spin precession frequency using an active nuclear spin maser. A 3He comagnetometer has been incorporated into the active spin maser system in order to cancel out the long-term drifts in the external magnetic field. Also, a double-cell geometry has been adopted in order to suppress the frequency shifts due to interaction with polarized Rb atoms. The first EDM measurement with the 129Xe active spin maser and the 3He comagnetometer has been conducted.

Ichikawa, Y.; Chikamori, M.; Ohtomo, Y.; Hikota, E.; Sakamoto, Y.; Suzuki, T.; Bidinosti, C. P.; Inoue, T.; Furukawa, T.; Yoshimi, A.; Suzuki, K.; Nanao, T.; Miyatake, H.; Tsuchiya, M.; Yoshida, N.; Shirai, H.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.; Asahi, K.

2014-03-01

128

Search for electric dipole moment in 129Xe atom using a nuclear spin oscillator  

NASA Astrophysics Data System (ADS)

We aim to measure the electric dipole moment (EDM) of a diamagnetic atom 129Xe using an optical-detection nuclear spin maser technique. The relation of EDM in a diamagnetic atom to nuclear Schiff moment and fundamental sources generating it is discussed, and the present status for the development of our experimental setup is presented.

Asahi, K.; Ichikawa, Y.; Chikamori, M.; Ohtomo, Y.; Hikota, E.; Suzuki, T.; Inoue, T.; Furukawa, T.; Yoshimi, A.; Suzuki, K.; Nanao, T.; Miyatake, H.; Tsuchiya, M.; Yoshida, N.; Shirai, H.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.

2014-01-01

129

Sensitizing solid state nuclear magnetic resonance of dilute nuclei by spin-diffusion assisted polarization transfers  

E-print Network

Sensitizing solid state nuclear magnetic resonance of dilute nuclei by spin- diffusion assisted polarization transfers Adonis Lupulescu and Lucio Frydman Citation: J. Chem. Phys. 135, 134202 (2011); doi: 10://jcp.aip.org/about/rights_and_permissions #12;THE JOURNAL OF CHEMICAL PHYSICS 135, 134202 (2011) Sensitizing solid state nuclear magnetic

Frydman, Lucio

130

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

E-print Network

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

Weise, Wolfram

131

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

NASA Astrophysics Data System (ADS)

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

Thurber, Kent R.; Tycko, Robert

2014-05-01

132

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

PubMed

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

Thurber, Kent R; Tycko, Robert

2014-05-14

133

Nuclear magnetic moments and the spin-orbit current in the relativistic mean field theory  

Microsoft Academic Search

The Dirac magnetic moments in the relativistic mean field theory are affected not only by the effective mass, but also by the spin-orbit current related to the spin-orbit force through the continuity equation. Previous arguments on the cancellation of the effective-mass effect in nuclear matter are not simply applied to finite nuclei to obtain the Schmidt values. Effects of the

Shigeru Nishizaki; Haruki Kurasawa; Toshio Suzuki

1988-01-01

134

Nuclear spin structure in dark matter search: The zero momentum transfer limit  

Microsoft Academic Search

We review the calculation of spin-dependent matrix elements relevant to\\u000ascattering of weakly interacting massive particles on nuclei. A comprehensive\\u000alist, to our knowledge, of the proton and neutron total spin expectation values\\u000a($<{\\\\bf S}_{p}>$ and $<{\\\\bf S}_{n}>$) calculated within different nuclear\\u000amodels is presented. These values allow a conclusion about the event rate\\u000aexpected in direct dark matter search

V. A. Bednyakov; F. Simkovic

2004-01-01

135

Interaction induced deformation in momentum distribution of spin polarized nuclear matter  

E-print Network

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

T. Frick; H. Müther; A. Sedrakian

2002-03-19

136

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

PubMed

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

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

2014-09-21

137

PUBLISHED ONLINE: 1 JULY 2012 | DOI: 10.1038/NPHYS2353 Ultrafast entangling gates between nuclear spins  

E-print Network

be used to hyperpolarize, manipulate and measure two nearby nuclear spins. Implementing a scheme that uses the successful use of a transient electron spin motivates the design of new molecules able to exploitHz. This weak coupling places a lower limit on the duration of a quantum logic operation between two spins

Loss, Daniel

138

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

PubMed Central

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. PMID:22938251

Thurber, Kent R.; Tycko, Robert

2012-01-01

139

Simultaneous sub-second hyperpolarization of the nuclear and electron spins of phosphorus in silicon  

E-print Network

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.

A. Yang; M. Steger; T. Sekiguchi; M. L. W. Thewalt; T. D. Ladd; K. M. Itoh; H. Riemann; N. V. Abrosimov; P. Becker; H. -J. Pohl

2009-03-09

140

Simultaneous sub-second hyperpolarization of the nuclear and electron spins of phosphorus in silicon  

E-print Network

We demonstrate a method which can hyperpolarize both the electron and nuclear spins of 31P donors in Si at low field, where both would be essentially unpolarized in equilibrium. It is based on the selective ionization of donors in a specific hyperfine state by optically pumping donor bound exciton hyperfine transitions, which can be spectrally resolved in 28Si. Electron and nuclear polarizations of 90% and 76%, respectively, are obtained in less than a second, providing an initialization mechanism for qubits based on these spins, and enabling further ESR and NMR studies on dilute 31P in 28Si.

Yang, A; Sekiguchi, T; Thewalt, M L W; Ladd, T D; Itoh, K M; Riemann, H; Abrosimov, N V; Becker, P; Pohl, H -J

2009-01-01

141

High-resolution spectroscopy of single NV defects coupled with nearby 13C nuclear spins in diamond  

NASA Astrophysics Data System (ADS)

We report a systematic study of the hyperfine interaction between the electron spin of a single nitrogen-vacancy (NV) defect in diamond and nearby 13C nuclear spins, by using pulsed electron-spin resonance spectroscopy. We isolate a set of discrete values of the hyperfine coupling strength ranging from 14 MHz to 400 kHz and corresponding to 13C nuclear spins placed at different lattice sites of the diamond matrix. For each lattice site, the hyperfine interaction is further investigated through nuclear-spin polarization measurements and by studying the magnetic field dependence of the hyperfine splitting. This work provides information that is relevant for the development of nuclear-spin-based quantum register in diamond.

Dréau, A.; Maze, J.-R.; Lesik, M.; Roch, J.-F.; Jacques, V.

2012-04-01

142

Anomalous nuclear spin relaxation of adsorbed helium-3  

Microsoft Academic Search

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

Brian P. Cowan

1983-01-01

143

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

E-print Network

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

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

2003-07-01

144

Role of dual nuclear baths on spin blockade leakage current bistabilities.  

PubMed

Spin-blockaded electronic transport across a double quantum dot (DQD) system represents an important advancement in the area of spin-based quantum information. The basic mechanism underlying the blockade is the formation of a blocking triplet state. The bistability of the leakage current as a function of the applied magnetic field in this regime is believed to arise from the effect of nuclear Overhauser fields on spin-flip transitions between the blocking triplet and the conducting singlet states. The objective of this paper is to present the nuances of considering a two bath model on the experimentally observed current bistability by employing a self consistent simulation of the nuclear spin dynamics coupled with the electronic transport of the DQD set up. In doing so, we first discuss the important subtleties involved in the microscopic derivation of the hyperfine mediated spin flip rates. We then give insights as to how the differences between the two nuclear baths and the resulting difference Overhauser field affect the two-electron states of the DQD and their connection with the experimentally observed current hysteresis curve. PMID:25374371

Buddhiraju, Siddharth; Muralidharan, Bhaskaran

2014-12-01

145

Direct observation of a nuclear spin excitation in Ho2Ti2O7.  

PubMed

A single nondispersive excitation is observed by means of neutron backscattering, at E_{0}=26.3 microeV in the spin ice Ho2Ti2O7 but not in the isotopically enriched 162Dy2Ti2O7 analogue. The intensity of this excitation is rather small, less, similar0.2% of the elastic intensity. It is clearly observed below 80 K but resolution limited only below approximately 65 K. The application of a magnetic field up to micro_{0}H=4.5 T, at 1.6 K, has no measurable effect on the energy or intensity. This nuclear excitation is believed to perturb the electronic, Ising spin system resulting in the persistent spin dynamics observed in spin ice compounds. PMID:19257221

Ehlers, G; Mamontov, E; Zamponi, M; Kam, K C; Gardner, J S

2009-01-01

146

Direct Observation of a Nuclear Spin Excitation in Ho2Ti2O7  

NASA Astrophysics Data System (ADS)

A single nondispersive excitation is observed by means of neutron backscattering, at E0=26.3?eV in the spin ice Ho2Ti2O7 but not in the isotopically enriched Dy2162Ti2O7 analogue. The intensity of this excitation is rather small, ?0.2% of the elastic intensity. It is clearly observed below 80 K but resolution limited only below ˜65K. The application of a magnetic field up to ?0H=4.5T, at 1.6 K, has no measurable effect on the energy or intensity. This nuclear excitation is believed to perturb the electronic, Ising spin system resulting in the persistent spin dynamics observed in spin ice compounds.

Ehlers, G.; Mamontov, E.; Zamponi, M.; Kam, K. C.; Gardner, J. S.

2009-01-01

147

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

SciTech Connect

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.

Bordbar, G. H. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha, P. O. Box 55134-441, Maragha (Iran, Islamic Republic of); Bigdeli, M. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Department of Physics, Zanjan University, Zanjan (Iran, Islamic Republic of)

2008-01-15

148

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

PubMed

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

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

2014-08-01

149

Pulsed Gradient Spin Echo Nuclear Magnetic Resonance Imaging of Diffusion in Granular Flow  

Microsoft Academic Search

We derive the formalism to obtain spatial distributions of collisional correlation times for macroscopic particles undergoing granular flow from pulsed gradient spin echo nuclear magnetic resonance diffusion data. This is demonstrated with an example of axial motion in the shear flow regime of a 3D granular flow in a horizontal rotating cylinder at one rotation rate.

Joseph D. Seymour; Arvind Caprihan; Stephen A. Altobelli; Eiichi Fukushima

2000-01-01

150

Pulsed Gradient Spin Echo Nuclear Magnetic Resonance Imaging of Diffusion in Granular Flow  

Microsoft Academic Search

We derive the formalism to obtain spatial distributions of collisional correlation times for macroscopic particles undergoing granular flow from pulsed gradient spin echo nuclear magnetic resonance diffusion data. This is demonstrated with an example of axial motion in the shear flow regime of a 3D granular flow in a horizontal rotating cylinder at one rotation rate. (c) 2000 The American

Joseph D. Seymour; Arvind Caprihan; Stephen A. Altobelli; Eiichi Fukushima

2000-01-01

151

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

E-print Network

563 Nuclear spin relaxation in a vinylidene fluoride and trifluoroethylene copolymer 70/30 I fluoride (PVF2) is known to possess a polar crystalline 3 phase were the chains are in the all of this system have been extensively studied [1]. Recently, it has been shown that vinylidene fluoride

Boyer, Edmond

152

Rabi and Larmor nuclear quadrupole double resonance of spin-1 nuclei.  

PubMed

We demonstrate the creation of two novel double-resonance conditions between spin-1 and spin-1/2 nuclei in a crystalline solid. Using a magnetic field oscillating at the spin-1/2 Larmor frequency, the nuclear quadrupole resonance (NQR) frequency is matched to the Rabi or Rabi plus Larmor frequency, as opposed to the Larmor frequency as is conventionally done. We derive expressions for the cross-polarization rate for all three conditions in terms of the relevant secular dipolar Hamiltonian, and demonstrate with these expressions how to measure the strength of the heterogenous dipolar coupling using only low magnetic fields. In addition, the combination of different resonance conditions permits the measurement of the spin-1/2 angular momentum vector using spin-1 NQR, opening up an alternate modality for the monitoring of low-field nuclear magnetic resonance. We use ammonium nitrate to explore these resonance conditions, and furthermore use the oscillating field to increase the signal-to-noise ratio per time by a factor of 3.5 for NQR detection of this substance. PMID:23231223

Prescott, D W; Malone, M W; Douglass, S P; Sauer, K L

2012-12-01

153

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

NASA Astrophysics Data System (ADS)

A one-dimensional Ising chain irradiated by weak resonant transverse field is the simplest model of quantum amplifier [Phys. Rev. A 71, 062338 (2005)]. The quantum state of the chain is stationary when all the qubits (spins) are in the same state. However, when the first qubit is flipped, it triggers a stimulated wave of flipped qubits, propagating through the chain. Such ``quantum domino" dynamics induces huge change in the total polarization, a macroscopic observable. Here we present the experimental demonstration of this quantum amplification process on a four-qubit system by using nuclear magnetic resonance technique. The physical system is a linear chain of four ^13C nuclear spins in a molecule of fully ^ 13C-labeled sodium butyrate dissolved in D2O. The pseudopure ground state (with all spins up) is prepared by multi-frequency partial saturation. The wave of flipped spins has been clearly observed when the first spin of the chain is flipped. We define a coefficient of amplification as the relative enhancement of the total polarization change. In our experimental system, the measured coefficient of amplification is about 3.

Lee, Jae-Seung; Adams, Travis; Khitrin, Anatoly

2007-03-01

154

Advances and applications of dynamic-angle spinning nuclear magnetic resonance  

SciTech Connect

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.

Baltisberger, J.H.

1993-06-01

155

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

NASA Astrophysics Data System (ADS)

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

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

2014-08-01

156

Active nuclear spin maser oscillation with double cell  

NASA Astrophysics Data System (ADS)

Uncertainty in the frequency precision of the planned experiment to search for a 129Xe atomic electric dipole moment is dominated by drifts in the frequency shift due to contact interaction of 129Xe with polarized Rb valence electrons. In order to suppress the frequency shift, a double-cell geometry has been adopted for the confinement of 129Xe gas. A new process has been identified to take part in the optical detection of spin precession. The parameters controlling the oscillation of the maser in this new double-cell arrangement were optimized. As a result, the frequency shift has been reduced by a factor of 10 or more from the former single-cell geometry.

Hikota, E.; Chikamori, M.; Ichikawa, Y.; Ohtomo, Y.; Sakamoto, Y.; Suzuki, T.; Bidinosti, C. P.; Inoue, T.; Furukawa, T.; Yoshimi, A.; Suzuki, K.; Nanao, T.; Miyatake, H.; Tsuchiya, M.; Yoshida, N.; Shirai, H.; Ino, T.; Ueno, H.; Matsuo, Y.; Fukuyama, T.; Asahi, K.

2014-03-01

157

Natural reference for nuclear high-spin states  

SciTech Connect

We suggest two new representations of the data on rotational nuclei. The first is reference-free and the second arises from a natural reference related to the variable moment of inertia model parameters of the ground-state band of the system. As such, neither representation contains any free parameters. By defining a 'configuration spin' we show how a new ground-state band reference can be applied. Its use allows a complete description of the changes associated with the first, and higher, band crossings. We apply these new representations to discuss the nature of the first band crossing along even-even isotopic chains in the erbium and osmium isotopes and to odd-even nuclei in the vicinity of {sup 158}Er.

Rowley, Neil; Ollier, James; Simpson, John [UMR 8608, Universite de Paris Sud/IN2P3, Division de Physique Theorique, Institut de Physique Nucleaire, F-91406 Orsay Cedex (France); STFC Daresbury Laboratory, Daresbury, Warrington WA44AD (United Kingdom)

2009-08-15

158

Microscopic control of $^{29}$Si nuclear spins near phosphorus donors in silicon  

E-print Network

Dynamic nuclear polarization of $^{29}$Si nuclei in resolved lattice sites near the phosphorus donors in natural silicon of has been created using the Overhauser and solid effects. Polarization has been observed as a pattern of well separated holes and peaks in the electron spin resonance line of the donor. The Overhauser effect in ESR hole burning experiments was used to manipulate the polarization of $^{29}$Si spins at ultra low (100-500 mK) temperatures and in high magnetic field of 4.6 T. Extremely narrow holes of 15 mG width were created after several seconds of pumping.

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

2014-01-01

159

Isovector spin observables in nuclear charge reactions at LAMPF  

SciTech Connect

LAMPF has undertaken a major development program to upgrade facilities for nuclear charge-exchange studies at intermediate energies. The major components of this upgrade are a medium-resolution spectrometer and neutron time-of-flight system for good resolution (delta E < 1 MeV) charge-exchange perograms in (n,p) and (p,n) respectively. Major emphasis is placed on polarization phenomena using polarized beams and analyzing the polarization of the outgoing particle.

McClelland, J.B.

1988-01-01

160

Spin- and phase transition in the spin crossover complex [Fe(ptz) 6](BF 4) 2 studied by nuclear inelastic scattering of synchrotron radiation and by DFT calculations  

NASA Astrophysics Data System (ADS)

Nuclear inelastic scattering (NIS) spectra of [Fe(ptz) 6](BF 4) 2 (ptz = 1- n-propyl-tetrazole) have been measured for five phases differing in spin state and crystallographic structure. Different spectral patterns have been found for the low-spin and high-spin phases and are described in terms of normal coordinate analysis of the complex molecule. For both low-spin and high-spin phases the conversion from ordered to disordered phase results in splitting of the observed NIS bands. Packing becomes visible in the NIS spectra via coupling of the Fe-N stretching vibrations with those of the terminal n-propyl groups. The DFT-based normal coordinate analysis also reveals the character of Raman markers.

Böttger, Lars H.; Chumakov, Aleksandr I.; Matthias Grunert, C.; Gütlich, Philipp; Kusz, Joachim; Paulsen, Hauke; Ponkratz, Ulrich; Rusanov, Ventzislav; Trautwein, Alfred X.; Wolny, Juliusz A.

2006-09-01

161

Spin-Dependent Structure Functions in Nuclear Matter and the Polarized EMC Effect  

SciTech Connect

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 F{sub 2N}{sup A}/F{sub 2N} ratio, that is, the European Muon Collaboration (EMC) effect. Applying this framework to determine g{sub 1p}{sup A}, we find that the ratio g{sub 1p}{sup A}/g{sub 1p} 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.

Cloeet, I.C. [Special Research Centre for the Subatomic Structure of Matter and Department of Physics and Mathematical Physics, University of Adelaide, South Australia 5005 (Australia); Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States); Bentz, W. [Department of Physics, School of Science, Tokai University, Hiratsuka-shi, Kanagawa 259-1292 (Japan); Thomas, A.W. [Jefferson Lab, 12000 Jefferson Avenue, Newport News, Virginia 23606 (United States)

2005-07-29

162

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

SciTech Connect

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 F{sub 2N}{sup A}/F{sub 2N} ratio, that is, the EMC effect. Applying this framework to determine g{sub 1p}{sup A}, we find that the ratio g{sub 1p}{sup A}/g{sub 1p} differs significantly from 1, 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.

I.C. Cloet; W. Bentz; A.W. Thomas

2005-04-01

163

High-pressure magic angle spinning nuclear magnetic resonance.  

PubMed

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 situ(13)C MAS NMR studies of mineral carbonation reaction intermediates and final products of forsterite (Mg(2)SiO(4)) reacted with supercritical CO(2) and H(2)O at 150 bar and 50°C are reported, with relevance to geological sequestration of carbon dioxide. PMID:21862372

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

164

High-pressure magic angle spinning nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

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.

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

165

Role of spin state on the geometry and nuclear quadrupole resonance parameters in hemin complex.  

PubMed

Theoretical calculations of structural parameters, 57Fe, 14N and 17 O electric field gradient (EFG) tensors for full size-hemin group have been carried out using density functional theory. These calculations are intended to shed light on the difference between the geometry parameters, nuclear quadrupole coupling constants (QCC), and asymmetry parameters (eta Q) found in three spin states of hemin; doublet, quartet and sextet. The optimization results reveal a significant change for propionic groups and porphyrin plane in different spin states. It is found that all principal components of EFG tensor at the iron site are sensitive to electronic and geometry structures. A relationship between the EFG tensor at the 14N and 17 O sites and the spin state of hemin complex is also detected. PMID:18353527

Behzadi, Hadi; van der Spoel, David; Esrafili, Mehdi D; Parsafar, Gholam Abbas; Hadipour, Nasser L

2008-05-01

166

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

NASA Astrophysics Data System (ADS)

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

Sorte, Eric G.

167

Optically induced nuclear spin polarization in a single GaAs/AlGaAs quantum well probed by a resistance detection method in the fractional quantum Hall regime  

E-print Network

We study the optically pumped nuclear spin polarization in a single GaAs/AlGaAs quantum well in the quantum Hall system. We apply resistive detection via the contact hyperfine interaction, which provides high sensitivity and selectivity, to probe a small amount of polarized nuclear spins in a single well. The properties of the optical nuclear spin polarization are clearly observed. We theoretically discuss the nuclear spin dynamics accompanied with doped electrons to analyze the experimental data. The optical nuclear polarization spectra exhibit electron-spin-resolved lowest Landau level interband transitions. We find that the phonon emission process, which normally assists the optical pumping process, influences the optical nuclear spin polarization. We also discuss that the electron-electron interaction can play an important role in the optical nuclear spin polarization.

K. Akiba; T. Yuge; S. Kanasugi; K. Nagase; Y. Hirayama

2012-06-22

168

Nuclear Spin-Lattice Relaxation Time Due to the Orbital Interaction  

Microsoft Academic Search

In the free electron model the spin-lattice relaxation time {T1}(orb) due to the interaction with the orbital motion of conduction electrons diverges if the nuclear Zeeman energy is neglected. Without neglecting it, {T1}(orb) with the field dependence of a form log(Hext) is derived for high magnetic fields. The divergence which arises for Hext{=}0 is removed by taking into account the

Eijiro Haga; Syozo Maeda

1972-01-01

169

NUCLEAR RELAXATION AND SPIN DYNAMICS IN NMP TCNQ F. DEVREUX (*), M. GUGLIELMI and M. NECHTSCHEIN (*)  

E-print Network

541 NUCLEAR RELAXATION AND SPIN DYNAMICS IN NMP TCNQ F. DEVREUX (*), M. GUGLIELMI and M été effectuées en fonction de la fréquence dans des echantillons de NMP TCNQ sélectivement deutériés électroniques localisés sur les chaines de NMP et associés à un transfert de charge incomplet. Après

Paris-Sud XI, Université de

170

Nuclear spin-lattice relaxation: A microscopic local probe for systems exhibiting the quantum Hall effect  

Microsoft Academic Search

Theory of magnetic quantum oscillations in the nuclear spin-lattice relaxation rate-T-11, in quasi-two-dimensional conductors at low temperatures and under strong magnetic fields, is presented. We show a close similarity between the magnetic field dependence of T-11 and that of rhoxx in the quantum Hall effect. The shape and the amplitude of the oscillations in T-11 depend strongly on band anisotropy,

I. D. Vagner; Tsofar Maniv

1988-01-01

171

Nuclear-spin relaxation of ²º?Pb in ferroelectric powders  

SciTech Connect

The ²º?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 ²º?Pb in PT and PZT below room temperature. We find that above T? 50 K, longitudinal relaxation rate follows the T² 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

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

2008-02-05

172

Violation of entropic Leggett-Garg inequality in nuclear spins  

NASA Astrophysics Data System (ADS)

We report an experimental study of recently formulated entropic Leggett-Garg inequality (ELGI) by Usha Devi [Phys. Rev. APLRAAN1050-294710.1103/PhysRevA.87.052103 87, 052103 (2013)]. This inequality places a bound on the statistical measurement outcomes of dynamical observables describing a macrorealistic system. Such a bound is not necessarily obeyed by quantum systems, and therefore provides an important way to distinguish quantumness from classical behavior. Here we study ELGI using a two-qubit nuclear magnetic resonance system. To perform the noninvasive measurements required for the ELGI study, we prepare the system qubit in a maximally mixed state as well as use the “ideal negative result measurement” procedure with the help of an ancilla qubit. The experimental results show a clear violation of ELGI by over four standard deviations. These results agree with the predictions of quantum theory. The violation of ELGI is attributed to the fact that certain joint probabilities are not legitimate in the quantum scenario, in the sense they do not reproduce all the marginal probabilities. Using a three-qubit system, we also demonstrate that three-time joint probabilities do not reproduce certain two-time marginal probabilities.

Katiyar, Hemant; Shukla, Abhishek; Rao, K. Rama Koteswara; Mahesh, T. S.

2013-05-01

173

Rotor Design for High Pressure Magic Angle Spinning Nuclear Magnetic Resonance  

SciTech Connect

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.

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

174

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

E-print Network

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.

A. E. Sitnitsky

2011-08-02

175

Structure and dynamics of porcine submaxillary mucin as determined by natural abundance carbon-13 NMR spectroscopy  

SciTech Connect

Nearly all of the resonances in the /sup 13/C NMR spectrum of porcine submaxillary mucin glycoprotein (PSM) have been assigned to the peptide core carbons and to the carbons in the eight different oligosaccharide side chains that arise from the incomplete biosynthesis of the sialylated A blood group pentasaccharide. By use of these assignments, a nearly complete structural analysis of intact PSM has been performed without resorting to degradative chemical methods. Considerable structural variability in the carbohydrate side chains was observed between mucins obtained from different animals, while no variability was observed between glands in a single animal. The dynamics of the PSM core and carbohydrate side chains were examined by using the carbon-13 nuclear magnetic resonance relaxation times and nuclear Overhauser enhancements of each assigned carbon resonance. The peptide core of PSM exhibits internal segmental flexibility that is virtually identical with that of ovine submaxillary mucin (OSM), whose carbohydrate side chain consists of the ..cap alpha..-NeuNAc(2-6)..cap alpha..-Ga1NAc disaccharide. These results differ from most reports of glycoprotein dynamics, which typically find the terminal carbohydrate residues to be undergoing rapid internal rotation about their terminal glycosidic bonds. The results reported here are consistent with previous studies on the conformations of the A and H determinants derived from model oligosaccharides and further indicate that the conformations of these determinants are unchanged when covalently bound to the mucin peptide core. In spite of their carbohydrate side-chain heterogeneity, mucins appear to be ideal glycoproteins for the study of O-linked oligosaccharide conformation and dynamics and for the study of the effects of glycosylation on polypeptide conformation and dynamics.

Gerken, T.A.; Jentoft, N.

1987-07-28

176

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

177

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

PubMed

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

McCain, D C

1995-09-01

178

Nuclear Spin relaxation mediated by Fermi-edge electrons in n-type GaAs  

NASA Astrophysics Data System (ADS)

A method based on the optical orientation technique was developed to measure the nuclear-spin lattice relaxation time T 1 in semiconductors. It was applied to bulk n-type GaAs, where T 1 was measured after switching off the optical excitation in magnetic fields from 400 to 1200 G at low (< 30 K) temperatures. The spin-lattice relaxation of nuclei in the studied sample with n D = 9 × 1016 cm-3 was found to be determined by hyperfine scattering of itinerant electrons (Korringa mechanism) which predicts invariability of T 1 with the change in magnetic field and linear dependence of the relaxation rate on temperature. This result extends the experimentally verified applicability of the Korringa relaxation law in degenerate semiconductors, previously studied in strong magnetic fields (several Tesla), to the moderate field range.

Kotur, M.; Dzhioev, R. I.; Kavokin, K. V.; Korenev, V. L.; Namozov, B. R.; Pak, P. E.; Kusrayev, Yu. G.

2014-03-01

179

Nuclear spin-lattice relaxation from fractional wobbling in a cone  

E-print Network

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

A. E. Sitnitsky

2011-01-13

180

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

SciTech Connect

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.

Bigdeli, M. [Department of Physics, Zanjan University, Post Office Box 45195-313, Zanjan (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha, Post Office Box 55134-441, Maragha (Iran, Islamic Republic of); Bordbar, G. H. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of); Research Institute for Astronomy and Astrophysics of Maragha, Post Office Box 55134-441, Maragha (Iran, Islamic Republic of); Poostforush, A. [Department of Physics, Shiraz University, Shiraz 71454 (Iran, Islamic Republic of)

2010-09-15

181

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

NASA Astrophysics Data System (ADS)

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

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

2008-02-01

182

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

183

A study of the spin-echo spin-locking effect in multi-pulse sequences in 14N nuclear quadrupole resonance  

NASA Astrophysics Data System (ADS)

Experimental evidence of observing a rather unusual spin-locking spin echo (SLSE) effect in the fields of two multi-pulse sequences ( ?0) x - ( ? - ?x - 2 ? - ?x - 2 ? - ?- x - 2 ? - ?- x - ?) n and ( ?0) x - ( ? - ?x - 2 ? - ?y - ?) n in 14N nuclear quadrupole resonance is presented. It was demonstrated that the SLSE effect is observed only in the even pulse intervals of both sequences. All experiments were carried out at room temperature on a powder sample of NaNO 2. A theoretical description of the effect is given.

Mikhaltsevitch, V. T.

2005-12-01

184

Spin Projection in the Shell Model Monte Carlo Method and the Spin Distribution of Nuclear Level Densities  

SciTech Connect

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

Alhassid, Y.; Liu, S. [Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520 (United States); Nakada, H. [Department of Physics, Chiba University, Inage, Chiba 263-8522 (Japan)

2007-10-19

185

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

PubMed

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

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

2011-10-01

186

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

PubMed

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. PMID:25362315

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

2014-10-28

187

Interlayer transport of nuclear spin polarization in ? = 2/3 quantum Hall states  

SciTech Connect

We investigated the interlayer diffusion of nuclear spin polarization (NSP) by using the phase transition point of quantum Hall states at a Landau level filling factor of ? ? 2/3 in a double quantum well sample. When the NSP is current-pumped in one layer, the magnetoresistance in the other layer is enhanced after a delay of 150 s and the raising speed of this layer is lower than that of the pumped layer. The delay and lower value of the raising speed are explained by the diffusion of NSP.

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

2013-12-04

188

Spin-locking of half-integer quadrupolar nuclei in nuclear magnetic resonance of solids: creation and evolution of coherences.  

PubMed

Spin-locking of half-integer quadrupolar nuclei, such as 23Na (I=3/2) and 27Al (I=5/2), is of renewed interest owing to the development of variants of the multiple-quantum and satellite-transition magic angle spinning (MAS) nuclear magnetic resonance experiments that either utilize spin-locking directly or offer the possibility that spin-locked states may arise. However, the large magnitude and, under MAS, the time dependence of the quadrupolar interaction often result in complex spin-locking phenomena that are not widely understood. Here we show that, following the application of a spin-locking pulse, a variety of coherence transfer processes occur on a time scale of approximately 1/omegaQ before the spin system settles down into a spin-locked state which may itself be time dependent if MAS is performed. We show theoretically for both spin I=3/2 and 5/2 nuclei that the spin-locked state created by this initial rapid dephasing typically consists of a variety of single- and multiple-quantum coherences and nonequilibrium population states and we discuss the subsequent evolution of these under MAS. In contrast to previous work, we consider spin-locking using a wide range of radio frequency field strengths, i.e., a range that covers both the "strong-field" (omega1 > omegaQPAS and "weak-field" (omega1 < omegaQPAS limits. Single- and multiple-quantum filtered spin-locking experiments on NaNO2, NaNO3, and Al(acac)3, under both static and MAS conditions, are used to illustrate and confirm the results of the theoretical discussion. PMID:15268416

Ashbrook, Sharon E; Wimperis, Stephen

2004-02-01

189

Spin state of Mn3O4 investigated by 55Mn nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

The 55Mn nuclear magnetic resonance spectrum for the spinel oxide Mn3O4 was measured at low temperature to investigate the spin structure in the ground state. The spectrum consists of three peaks in the frequency range of 250-265 MHz, which corresponds to the hyperfine field range of 24-25 T. The temperature dependence of the spectrum and the rf enhancement factor show that Mn3+ ions have two different magnetic moments, one of which is strongly related to the commensurate-incommensurate phase transition. This is consistent with the picture of two magnetic moments R and S claimed from the results of a neutron experiment. Comparison with a heat-treated sample suggests a relation between the two different magnetic moments and the occupation sites of manganese ions, the tetrahedral and octahedral sites. Theoretical estimations of the dipolar hyperfine field and the observed peak splitting predict that the magnetic moments of R and S differ by 5% at maximum. The spin-spin relaxation time has a frequency dependence that induces spectrum broadening and further splitting of the peak coming from S, indicating that the Suhl-Nakamura interaction is the major relaxation mechanism in Mn3O4.

Jo, Euna; An, Kyongmo; Shim, Jeong Hyun; Kim, Changsoo; Lee, Soonchil

2011-11-01

190

Limits on New Long Range Nuclear Spin-Dependent Forces Set with a K-{sup 3}He Comagnetometer  

SciTech Connect

A magnetometer using spin-polarized K and {sup 3}He atoms occupying the same volume is used to search for anomalous nuclear spin-dependent forces generated by a separate {sup 3}He spin source. We measure changes in the {sup 3}He spin precession frequency with a resolution of 18 pHz and constrain anomalous spin forces between neutrons to be less than 2x10{sup -8} of their magnetic or less than 2x10{sup -3} of their gravitational interactions on a length scale of 50 cm. We present new limits on neutron coupling to light pseudoscalar and vector particles, including torsion, and constraints on recently proposed models involving unparticles and spontaneous breaking of Lorentz symmetry.

Vasilakis, G.; Brown, J. M.; Kornack, T. W.; Romalis, M. V. [Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

2009-12-31

191

Controlling nuclear spin exchange via optical Feshbach resonances in ${}^{171}$Yb  

E-print Network

Nuclear spin exchange occurs in ultracold collisions of fermionic alkaline-earth-like atoms due to a difference between s- and p-wave phase shifts. We study the use of an optical Feshbach resonance, excited on the ${}^1S_0 \\to {}^3P_1$ intercombination line of ${}^{171}$Yb, to affect a large modification of the s-wave scattering phase shift, and thereby optically mediate nuclear exchange forces. We perform a full multichannel calculation of the photoassociation resonances and wave functions and from these calculate the real and imaginary parts of the scattering length. As a figure of merit of this interaction, we estimate the fidelity to implement a $\\sqrt{SWAP}$ entangling quantum logic gate for two atoms trapped in the same well of an optical lattice. For moderate parameters one can achieve a gate fidelity of $\\sim95% $ in a time of $\\sim 50 \\mu$s.

Reichenbach, Iris; Deutsch, Ivan H

2009-01-01

192

Controlling nuclear spin exchange via optical Feshbach resonances in ${}^{171}$Yb  

E-print Network

Nuclear spin exchange occurs in ultracold collisions of fermionic alkaline-earth-like atoms due to a difference between s- and p-wave phase shifts. We study the use of an optical Feshbach resonance, excited on the ${}^1S_0 \\to {}^3P_1$ intercombination line of ${}^{171}$Yb, to affect a large modification of the s-wave scattering phase shift, and thereby optically mediate nuclear exchange forces. We perform a full multichannel calculation of the photoassociation resonances and wave functions and from these calculate the real and imaginary parts of the scattering length. As a figure of merit of this interaction, we estimate the fidelity to implement a $\\sqrt{SWAP}$ entangling quantum logic gate for two atoms trapped in the same well of an optical lattice. For moderate parameters one can achieve a gate fidelity of $\\sim95% $ in a time of $\\sim 50 \\mu$s.

Iris Reichenbach; Paul S. Julienne; Ivan H. Deutsch

2009-05-28

193

High-performance algorithm to calculate spin- and parity-dependent nuclear level densities  

SciTech Connect

A new algorithm for calculating the spin- and parity-dependent shell-model nuclear level densities using the moments method in the proton-neutron formalism is presented. A new, parallelized code based on this algorithm was developed and tested using up to 4000 cores for a set of nuclei from the sd-, pf-, and pf+g{sub 9/2}-model spaces. By comparing the nuclear level densities at low excitation energy for a given nucleus calculated in two model spaces, such as pf and pf+g{sub 9/2}, one can estimate the ground-state energy in the larger model space, which is not accessible to direct shell-model calculations due to the unmanageable dimension. Examples for the ground-state energies of for {sup 64}Ge and {sup 68}Se in the pf+g{sub 9/2} model space are presented.

Sen'kov, R. A.; Horoi, M. [Department of Physics, Central Michigan University, Mount Pleasant, Michigan 48859 (United States)

2010-08-15

194

A High-Performance Fortran Code to Calculate Spin- and Parity-Dependent Nuclear Level Densities  

E-print Network

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+g9/2 - model spaces. Examples of the calculations for 28Si (in the sd-model space) and 64Ge (in the pf+g9/2-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+g9/2, 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.

Sen'kov, R; Zelevinsky, V G

2012-01-01

195

A High-Performance Fortran Code to Calculate Spin- and Parity-Dependent Nuclear Level Densities  

E-print Network

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+g9/2 - model spaces. Examples of the calculations for 28Si (in the sd-model space) and 64Ge (in the pf+g9/2-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+g9/2, 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.

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

2012-06-20

196

Prediction of nuclear spin based on the behavior of ?-particle preformation probability  

NASA Astrophysics Data System (ADS)

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 ?-nucleus potential in the well-established double-folding model. The main effect of antisymmetrization under exchange of nucleons between the ? and daughter nuclei has been included in the folding model through the finite-range exchange part of the NN interaction. The ?-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, S?, for ten even-even and odd mass heavy nuclei from Po to No isotopes. We found that S? has a regular behavior with N if the ? 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 S? is found when protons and neutrons holes exist below the Fermi levels. Based on the similarity in the behavior of S? 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.

Ismail, M.; Adel, A.

2013-11-01

197

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

NASA Astrophysics Data System (ADS)

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

Crabtree, Kyle N.; McCall, Benjamin J.

2012-06-01

198

Treatment of scalar-relativistic effects on nuclear magnetic shieldings using a spin-free exact-two-component approach.  

PubMed

A cost-effective treatment of scalar-relativistic effects on nuclear magnetic shieldings based on the spin-free exact-two-component theory in its one-electron variant (SFX2C-1e) is presented. The SFX2C-1e scheme gains its computational efficiency, in comparison to the four-component approach, from a focus on spin-free contributions and from the elimination of the small component. For the calculation of nuclear magnetic shieldings, the separation of spin-free and spin-dependent terms in the parent four-component theory is carried out here for the matrix representation of the Dirac equation in terms of a restricted-magnetically balanced gauge-including atomic orbital basis. The resulting spin-free four-component matrix elements required to calculate nuclear magnetic shieldings are then used to construct the corresponding SFX2C-1e Hamiltonian and its perturbed counterpart in the context of SFX2C-1e analytic derivative theory. To demonstrate the applicability of the approach, we report coupled-cluster calculations for prototypical problems such as the (17)O shieldings of transition-metal oxo complexes (MO4(2-), M = Cr, Mo, and W) and the (129)Xe shieldings of xenon fluorides (XeF2, XeF4, and XeF6). PMID:23927241

Cheng, Lan; Gauss, Jürgen; Stanton, John F

2013-08-01

199

Neutrino-nucleon scattering rates in protoneutron stars and nuclear correlations in the spin S = 1 channel  

Microsoft Academic Search

The neutrino-nucleon cross-section is calculated in dense nuclear matter at finite temperature, in view of applications to\\u000a supernovae and protoneutron stars. The main contribution to this parameter is provided by the axial response function. Nuclear\\u000a correlations play an important role: while the v-N crosssection is usually reduced by correlations, a collective mode in the spin S = 1 channel may

L. Mornasa; Avda Calvo Sotelo

200

Neutrino-nucleon scattering rates in protoneutron stars and nuclear correlations in the spin S = 1 channel  

Microsoft Academic Search

.  The neutrino-nucleon cross-section is calculated in dense nuclear matter at finite temperature, in view of applications to\\u000a supernovae and protoneutron stars. The main contribution to this parameter is provided by the axial response function. Nuclear\\u000a correlations play an important role: while the ?-N cross-section is usually reduced by correlations, a collective mode in the spin S = 1 channel may

L. Mornas; Avda Calvo Sotelo

2006-01-01

201

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

PubMed Central

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

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

2012-01-01

202

The Study of High Spin States in Nuclear Rotation by the Cranked Nilsson Strutinsky Model  

SciTech Connect

A heavy-ion reaction can populate nuclear states of very high angular momentum with values of the order of I = 60 achievable. The reaction produces such configurations with a considerable internal excitation, but the emission of a few neutrons reduces the excitation energy effectively while not decreasing the spin by much. At sufficiently high spin the pairing is destroyed completely and the rigid-body moment of inertia becomes a good approximation. Even in this regime, however, the single-particle structure remains important and shell effects can be studied in terms of a rotating phenomenological shell model. On the theoretical side the cranked Nilsson strutinsky model has proved to be a successful tool to describe rapidly rotating nucleus. Indeed, this model gives a microscopic description of the influence of rotation on single-particle motion. This paper will concentrate on introduction to the cranked Nilsson strutinsky model in details. First, we explain the cranking model and the rotating liquid-drop model, then introduce the shell correction method. Also, we describe terminating bands, which show a continuous transition from high collectivity to a pure particle-hole state.

Kardan, A.; Miri-Hakimabad, H.; Rafat-Motevalli, L. [Physics Department, Faculty of Science, Ferdowsi University of Mashhad, P. O. Box 91775-1436, Mashhad (Iran, Islamic Republic of)

2010-11-24

203

Resonant microwave cavity for 8.512 GHz optically detected electron spin resonance with simultaneous nuclear magnetic resonance  

E-print Network

Resonant microwave cavity for 8.5­12 GHz optically detected electron spin resonance with simultaneous nuclear magnetic resonance J. S. Colton1,a and L. R. Wienkes2 1 Department of Physics online 16 March 2009 We present a newly developed microwave resonant cavity for use in optically detected

Hart, Gus

204

Nuclear spin imaging with hyperpolarized nuclei created by brute force method  

NASA Astrophysics Data System (ADS)

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

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

205

Separation of aromatic-carbon 13C NMR signals from di-oxygenated alkyl bands by a chemical-shift-anisotropy filter  

Microsoft Academic Search

Selection of alkyl-carbon and suppression of aromatic-carbon 13C nuclear magnetic resonance (NMR) signals has been achieved by exploiting the symmetry-based, systematic difference in their 13C chemical-shift anisotropies (CSAs). Simple three- or five-pulse CSA-recoupling sequences with “gamma-integral” cleanly suppress the signals of all sp2- and sp-hybridized carbons. The chemical-shift-anisotropy-based dephasing is particularly useful for distinguishing the signals of di-oxygenated alkyl (O–C–O)

J.-D. Mao; K. Schmidt-Rohr

2004-01-01

206

Nuclear Spin Relaxation of Deuterium Molecule in Deuterium Gas and in Solid Argon  

NASA Astrophysics Data System (ADS)

Nuclear spin relaxation times have been measured for molecular deuterium, both as a pure gas and as a dilute impurity in a host matrix of solid argon. In the gas, T(,1) was measured as function of temperature and of the density (rho), over the ranges from 25 to 125 K and from 2 to 12 amagat. For the ortho species of the gas, the measurements were used to calculate T(,1)/(rho), which agreed with previous measurements by Hardy. The T(,1) measurements are consistent with a model of a primary relaxation mechanism resulting from an intramolecular interaction with the molecular angular momentum, which has fluctuating components because of collisions between gas molecules. Also, some measurements were made of the deuteron T(,1) in HD gas; only a small discrepancy from Hardy's results was observed. T(,1) and T(,2) of p-D(,2) were measured for dilute mixtures of molecular deuterium in solid argon at temperatures from 5.6 to 55 K. The mixtures were purposely dilute in order to reduce intermolecular interactions between deuterium molecules. The primary relaxation mechanism in these mixtures is, as for the gaseous samples, the intramolecular interaction with the fluctuating molecular spin; in this case, the molecular spin fluctuations are caused by phonon induced modulation of electric field gradients at the molecular sites. The results can described by Fedders' calculation of the intramolecular interaction, and by the Van Kronendank and Walker model of anharmonic phonon interactions with the molecular quadrupole moment. In addition, evidence for an additional relaxation mechanism was observed. This extra relaxation is probably the result of a direct interaction with the nuclear quadrupole moment. The field fluctuations which cause the direct relaxation are probably the result of molecular motions. The mixture samples were mixed in the liquid phase, and then frozen. T(,1) was also measured in the liquid mixtures, and line shape spectra were recorded. A shift of the deuterium resonance frequency was observed between gas phase and liquid phase mixtures. All of the relaxation time measurements were performed using pulsed NMR techniques, at a frequency of 55 MHz in a 8.5 T superconducting magnet. A liquid helium flow cryostat system was used to control the temperature of the samples. A general-purpose NMR spectrometer, designed and assembled by the author, was used to collect the NMR data.

Mohr, Gregory Alan

207

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

NASA Astrophysics Data System (ADS)

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

Das, R.; Odom, A. L.

2007-12-01

208

Manipulation of phase and amplitude modulation of spin magnetization in magic angle spinning nuclear magnetic resonance in the presence of molecular diffusion  

NASA Astrophysics Data System (ADS)

Nuclear magnetic resonance (NMR) experiments with a spinning sample [magic angle sample spinning (MASS)] are used to remove the line broadening in composite systems, where the susceptibility contrast of its constituents gives rise to an inhomogeneous field that causes a line broadening and obscures chemical information. The NMR signal in these experiments has a phase and an amplitude part. In the absence of diffusion, i.e., in the MASS spectra of solids, the amplitude of the signal from an isochromat is a constant independent of position and time and the phase is a periodic function of the rotor frequency ?r. In fluids, the amplitude of a spin packet is a function of its position and time. The amplitude modulation and relaxation in diffusive MASS encodes the dynamics of motion and the landscape (geometry of pores and field gradients) probed by the motion. Here we use spin manipulation—total suppression of sidebands (TOSS)—to suppress the effects of phase with the goal of isolating the amplitude term. By the TOSS sequence the phase factor at time t for a spin packet at an azimuthal angle ? is made to depend on ? only as a function of ?rt-?, which suppresses the sidebands in solids upon an integration over ?. Due to molecular diffusion, the amplitude part depends on ?, and, thus, diffusive TOSS cannot suppress the sidebands. The residual sidebands carry the information of dynamics and pore and magnetic field geometry, in addition, by reducing the size of the sidebands, TOSS is of course, also useful in identifying various fluid components in situ. The diffusive MASS gives a measure of the spread in local fields and diffusive TOSS gives a measure of the spread in local gradients.

Liu, Yun; Leu, Gabriela; Singer, S.; Cory, D. G.; Sen, Pabitra N.

2001-04-01

209

Nuclear Jacobi and Poincaré Transitions at High Spins and Temperatures: Account~of~Dynamic~Effects~and~Large-Amplitude Motion  

E-print Network

We present a theoretical analysis of the competition between so-called nuclear Jacobi and Poincar\\'e shape transitions in function of spin - at high temperatures. The latter condition implies the method of choice - a realistic version of the nuclear Liquid Drop Model (LDM), here: the Lublin-Strasbourg Drop (LSD) model. We address specifically the fact that the Jacobi and Poincar\\'e shape transitions are accompanied by the flattening of total nuclear energy landscape as function of the relevant deformation parameters what enforces large amplitude oscillation modes that need to be taken into account. For that purpose we introduce an approximate form of the collective Schr\\"odinger equation whose solutions are used to calculate the most probable deformations associated with both types of transitions and discuss the physical consequences in terms of the associated critical-spin values and transitions themselves.

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

2013-08-14

210

Continuous re-hyperpolarization of nuclear spins using parahydrogen: theory and experiment.  

PubMed

The continuous re-hyperpolarization of nuclear spins in the liquid state by means of parahydrogen (para-H2) and chemical exchange at low magnetic fields was recently discovered and offers intriguing perspectives for many varieties of magnetic resonance. In this contribution, we provide a theoretical assessment of this effect and compare the results to experimental data. A distinct distribution of polarization is found, which shares some features with experimental data and, interestingly, does not directly correspond to the loss of the singlet order of para-H2. We derived expressions for the magnetic field and para-H2-substrate interaction time, for which the polarization transfer is maximal. This work sheds light onto the effect of continuous hyperpolarization and elucidates the underlying mechanism, which may facilitate the development of an optimized catalyst. As an application, continuous hyperpolarization may enable highly sensitive nuclear magnetic resonance at very low magnetic fields, for example, for the cost-efficient screening of drugs. PMID:25079961

Hövener, Jan-Bernd; Knecht, Stephan; Schwaderlapp, Niels; Hennig, Jürgen; von Elverfeldt, Dominik

2014-08-25

211

Carbon13 kinetic isotope effects on pyruvate decarboxylation. II. Solvent effects in model systems  

Microsoft Academic Search

Carbon-13 kinetic isotope effects were determined for the decarboxylation of pyruvate by thiamin and for the decarboxylation of 2-(1-carboxy-1-hydroxyethyl)-3,4-dimethylthiazolium chloride (a covalent pyruvate-thiamin adduct) in water and in aqueous ethanol. The kinetic isotope effect for the decarboxylation step in the second system increased from 1.051 in HâO to approximately 1.058 in 50% v\\/v ethanol. The isotope effect in the thiamin

Frank Jordan; Donald J. Kuo; Ernst U. Monse

1978-01-01

212

Improving Estimates of Nuclear-Spin Relaxation Time (T1) in Surface-NMR Experiments  

NASA Astrophysics Data System (ADS)

Surface nuclear magnetic resonance (NMR) is a relatively novel and powerful geophysical technique for investigating hydrological characteristics of shallow aquifers from the Earth's surface in a non-invasive way. Large current loops of approximately 100 m diameter laid on the ground transmit electromagnetic pulses into the subsurface. These pulses excite spins of protons in groundwater molecules out of their equilibrium state in the Earth's magnetic field. The spin response is recorded on either coincident or offset surface receiver loops of similar dimension. The amplitudes of the response signals recorded after single-pulse excitation provide estimates of water-content in the shallow subsurface. Another important parameter is the NMR relaxation time T1, from which information on pore structure or even hydraulic conductivity can be inferred under favorable circumstances. T1 data are conventionally acquired using a scheme that involves two sequential pulses of electromagnetic energy, the second of which is phase-shifted by ? relative to the first. We show that common imperfections in the transmitted pulses and variations of the excitation field with distance from the transmitter introduce significant bias in conventional estimates of T1. Here, we propose a novel yet simple modification to the conventional scheme that is theoretically capable of resolving this problem. The proposed scheme comprises a conventional double-pulse sequence followed by an additional double-pulse sequence for which the 2nd pulse is in-phase with the 1st pulse. Subtracting the voltage signals measured during the two double-pulse sequences (i.e., phase cycle) eliminates the bias. This strategy of continuously cycling the phase of the 2nd pulse between ? and 0 in sequential double-pulse experiments and then subtracting the resulting voltages is a promising step towards recording more reliable T1 data under general field conditions.

Walbrecker, Jan O.; Hertrich, Marian; Green, Alan G.

2011-03-01

213

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

PubMed Central

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

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

2011-01-01

214

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

E-print Network

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

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

2009-01-15

215

Characterization of quantum algorithms by quantum process tomography using quadrupolar spins in solid-state nuclear magnetic resonance.  

PubMed

NMR quantum computing with qubit systems represented by nuclear spins (I=12) in small molecules in liquids has led to the most successful experimental quantum information processors so far. We use the quadrupolar spin-32 sodium nuclei of a NaNO3 single crystal as a virtual two-qubit system. The large quadrupolar coupling in comparison with the environmental interactions and the usage of strongly modulating pulses allow us to manipulate the system fast enough and at the same time keeping the decoherence reasonably slow. The experimental challenge is to characterize the "calculation" behavior of the quantum processor by process tomography which is here adapted to the quadrupolar spin system. The results of a selection of quantum gates and algorithms are presented as well as a detailed analysis of experimental results. PMID:15974729

Kampermann, H; Veeman, W S

2005-06-01

216

Nuclear Magnetic Resonance Relaxivities: Investigations of Ultrahigh-Spin Lanthanide Clusters from 10 MHz to 1.4 GHz.  

PubMed

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

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

2014-11-10

217

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

NASA Astrophysics Data System (ADS)

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}. .

Bogorad, Paul Lev

1995-01-01

218

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

E-print Network

Nuclear spin relaxation of sodium cations in bacteriophage Pf1 solutions D. N. Sobieski, N. R The nuclear magnetic resonance NMR spectra for the I=3/2 23 Na cation dissolved into filamentous bacteriophage the 23 Na nuclear quadrupole moment and the electric field gradient produced by the negatively charged Pf

Augustine, Mathew P.

219

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

NASA Astrophysics Data System (ADS)

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

Neyens, G.

2013-07-01

220

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

PubMed

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 ? ? 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 ? has been found to decrease from 1.6 ± 0.1 at 350 K to 0.5 ± 0.1 at 135 K. PMID:21599063

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

2011-05-21

221

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

NASA Astrophysics Data System (ADS)

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.

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

2013-09-01

222

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

PubMed

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. Go?mez, J. I. Melo, C. G. Giribet, and M. C. Ruiz de Azu?a, 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

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

2013-09-01

223

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

E-print Network

succinate and ethanol [67, 68, 70]. The favored route of glucose metabolism, shown in Scheme I, follows the Embden- Meyerhof glycolytic sequence through the formation of PEP. Carbon dioxide fixation mediated by pEpCK in the conversion of pEp to OAA... is thought to be of major 25 GLUCOSE GLUCOSE 6-PHOSPIIATE FRUCTOSE 6-PHOSPIUITE FRUCIOSE 1, 6 GIPHOSPHATE COj HC ? NHI CHI HSC ? 0 ? QP C=O HIC ? OH CHAP HC=O HC ? OH HIC ? O~P GIP COj COSCoA Cal Clio COj C=O CHl COo C ? O ? QP Clio...

McCloskey, Diane Elizabeth

2012-06-07

224

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

E-print Network

be nujol. This sample also showed some bands due to water from incomplete drying. Figures 12 and 13 show infrared spectra of [Co(NH ) CO ]NO 13 which were also run as KBr pellets by R. D. George and J. L. Reden, Nalco Chemical Co. The strong bands... be nujol. This sample also showed some bands due to water from incomplete drying. Figures 12 and 13 show infrared spectra of [Co(NH ) CO ]NO 13 which were also run as KBr pellets by R. D. George and J. L. Reden, Nalco Chemical Co. The strong bands...

Philen, Rossanne McElroy

2012-06-07

225

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

E-print Network

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

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

2014-10-09

226

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

SciTech Connect

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

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

2013-11-28

227

Observation of zero-point quantum fluctuations of a single-molecule magnet through the relaxation of its nuclear spin bath.  

PubMed

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. PMID:24702408

Morello, A; Millán, A; de Jongh, L J

2014-03-21

228

Nuclear inelastic scattering of 1D polymeric Fe(II) complexes of 1,2,4-aminotriazole in their high-spin and low-spin state  

NASA Astrophysics Data System (ADS)

The vibrational properties of Fe(II) 1D spin crossover polymers have been characterized by nuclear inelastic scattering (NIS). The complexes under study were the tosylate and perchlorate salts of ([Fe(4-amino-1,2,4-triazole)3]^{+2})_n complexes. The complexes have LS (S = 0) marker bands in the range of 300-500 cm - 1, while the marker bands corresponding to the HS (S = 2) state are detected between 200 cm - 1 and 300 cm - 1, in line with the decreasing Fe-N bond strengths during the transition from LS to HS. Accompanying DFT calculations using the functional B3LYP and the basis set CEP-31G confirm these assignments.

Wolny, Juliusz A.; Rackwitz, Sergej; Achterhold, Klaus; Muffler, Kai; Schünemann, Volker

2012-03-01

229

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

SciTech Connect

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

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

1982-07-30

230

Physica E 34 (2006) 355358 Dynamics of nuclear spins appearing in transport measurements of an  

E-print Network

nonlinear transport between spin polarized edge channels is studied. The observed hysteresis of the I2V be calculated using the Landauer­Bu¨ ttiker multichannel formulae [5]. Assum- ing the absence of backscattering

Hohls, Frank

231

Analytic approach to nuclear rotational states: The role of spin - A minimal model -  

E-print Network

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 collective scissors mode in deformed nuclei. Various constraints from rotational symmetry are elucidated and discussed. We put special emphasis on the coupling of the spin part of the M1 operator to the low lying collective modes, and investigate how this coupling changes the sum rules.

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

2013-12-25

232

Correlations between 27Al magic-angle spinning nuclear magnetic resonance spectra and the coordination geometry of framework aluminates.  

PubMed

A range of aluminate sodalites of general formula M8(AlO2)12.X2, where M and X are a divalent cation and anion, respectively, has been synthesised. The structures of these materials, which contain a single aluminum environment, have been refined from powder X-ray or neutron diffraction data and the compounds further characterised using 27Al magic-angle spinning nuclear magnetic resonance (MAS NMR). Correlations between (i) the Al-O-Al bond angles and the 27Al chemical shift and (ii) the quadrupolar coupling constant and the distorted AlO4 tetrahedral geometry have been determined. PMID:7834310

Weller, M T; Brenchley, M E; Apperley, D C; Davies, N A

1994-04-01

233

Dynamics of exocyclic groups in the Escherichia coli O91 O-antigen polysaccharide in solution studied by carbon-13 NMR relaxation.  

PubMed

Carbon-13 relaxation data are reported for exocyclic groups of hexopyranosyl sugar residues in the repeating unit within the Escherichia coli O91 O-antigen polysaccharide in a dilute D2O solution. The measurements of T 1, T 2 and heteronuclear nuclear Overhauser enhancements were carried out at 310 K at two magnetic fields (16.4 T, 21.1 T). The data were analyzed using the standard and extended Lipari-Szabo models, as well as a conformational jump model. The extended version of the Lipari-Szabo and the two-site jump models were most successful for the hydroxymethyl groups of Gal and GlcNAc sugar residues. Different dynamics was found for the hydroxymethyl groups associated with different configurations (D-gluco, D-galacto) of the sugar residues, the latter being faster than the former. PMID:23897032

Soltesova, Maria; Kowalewski, Jozef; Widmalm, Göran

2013-09-01

234

63Cu nuclear magnetic resonance study of Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4): Ni-induced spin density oscillation and modification of the low energy spin fluctuations.  

PubMed

We report the results from a (63)Cu nuclear magnetic resonance (NMR) study of the electron-doped high temperature superconducting cuprate (HTSC) Pr(1.85)Ce(0.15)Cu(1-x)Ni(x)O(4). We find that Ni induces a magnetic broadening of the (63)Cu NMR spectra that can be interpreted in terms of an induced spin density oscillation about the Ni site, similar to that reported from (63)Cu NMR measurements on the hole-doped HTSCs when Zn is partially substituted for Cu. There is also an additional temperature-dependent contribution to the (63)Cu spin-lattice relaxation rate that can be interpreted in terms of an Ni-induced modification of the low energy spin fluctuations. Furthermore, the spin fluctuations are intrinsically spatially inhomogeneous and additional inhomogeneities are induced by Ni. PMID:21411886

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

2011-02-23

235

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

NASA Astrophysics Data System (ADS)

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.

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

2014-02-01

236

31P nuclear magnetic resonance studies of crayfish (Orconectes virilis). The use of inversion spin transfer to monitor enzyme kinetics in vivo.  

PubMed

31P nuclear-magnetic resonance (NMR) has been used to observed in vivo the steady-state levels of phosphorus-containing metabolites in the crayfish Orconectes virilis and the intracellular pH of the abdominal muscle was determined. Measurement of spin-lattice relaxation times and spin transfer experiments have enabled calculation of unidirectional rate constants and activation energies for the arginine kinase reaction in vivo. PMID:3996405

Butler, K W; Deslauriers, R; Geoffrion, Y; Storey, J M; Storey, K B; Smith, I C; Somorjai, R L

1985-05-15

237

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)

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.

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

2009-10-01

238

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

SciTech Connect

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)

Johnson, N.

1986-01-01

239

Symmetry energy from the nuclear collective motion: constraints from dipole, quadrupole, monopole and spin-dipole resonances  

NASA Astrophysics Data System (ADS)

The experimental and theoretical studies of Giant Resonances, or more generally of the nuclear collective vibrations, are a well-established domain in which sophisticated techniques have been introduced and firm conclusions reached after an effort of several decades. From it, information on the nuclear equation of state can be extracted, albeit not far from usual nuclear densities. In this contribution, which complements other contributions appearing in this topical issue, we survey some of the constraints that have been extracted recently concerning the parameters of the nuclear symmetry energy. Isovector modes, in which neutrons and protons are in opposite phase, are a natural source of information and we illustrate the values of symmetry energy around saturation deduced from isovector dipole and isovector quadrupole states. The isotopic dependence of the isoscalar monopole energy has also been suggested to provide a connection to the symmetry energy: relevant theoretical arguments and experimental results are thoroughly discussed. Finally, we consider the case of the charge-exchange spin-dipole excitations in which the sum rule associated with the total strength gives in principle access to the neutron skin and thus, indirectly, to the symmetry energy.

Colò, G.; Garg, U.; Sagawa, H.

2014-02-01

240

Nuclear Spins and Magnetic Moments by the alpha-Particle Model  

Microsoft Academic Search

Some properties of the light nuclei of the type nalpha+\\/-1 have been calculated on the basis of the alpha-particle model. By means of this description, spins and magnetic moments of the same nuclei are calculated here. The results for the magnetic moments of many of the nuclei are undetermined within a certain range of possible values since the relative order

R. G. Sachs

1939-01-01

241

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

NASA Astrophysics Data System (ADS)

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.

Fries, P. H.

242

Nuclear spin-orbit interaction and T-odd angular correlations in ternary fission  

E-print Network

T-odd angular correlations in ternary fission of 233-U and 235-U nuclei by slow polarized neutrons are not related to TRI (time reversal invariance) violation, but are caused by an effective spin-orbit interaction in the final state.

Barabanov, A L

2014-01-01

243

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

E-print Network

In the "nucleon-phase" model of binary fission, the transfer of nucleons between an A =126 {\\guillemotleft} nucleon core {\\guillemotright} and the primordial "cluster" can explain both the formation of high- spin states and the saw-tooth behavior of the variation, as a function of fragment mass, of the average angular momentum.

G. Mouze; C. Ythier; S. Hachem

2011-03-28

244

Nuclear spin-orbit interaction and T-odd angular correlations in ternary fission  

E-print Network

T-odd angular correlations in ternary fission of 233-U and 235-U nuclei by slow polarized neutrons are not related to TRI (time reversal invariance) violation, but are caused by an effective spin-orbit interaction in the final state.

A. L. Barabanov

2014-07-08

245

Curing chemistry of phenylethynyl-terminated imide oligomers: Model compounds, carbon-13 labeling and cure analysis  

NASA Astrophysics Data System (ADS)

Phenylethynyl-terminated imide oligomers (PETI) are currently considered the state-of-the-art high performance resins for aerospace applications. The processing of these resins is more facile because of their low molecular weight, but PETI's cure to form a tough, solvent-resistant material. However, the final cure structure was a complete mystery. Hence, the present study was set forth with three essential goals. The determination of the final structure of the crosslinked polymer is of obvious importance. Second, the crosslinking mechanism and controlling factors is also of interest. Lastly, the final structure of the crosslinked polymers was correlated with mechanical and thermal properties, thereby helping to establish the structure-processing-properties relationships for PETI resins. These goals were accomplished by using a combination of synthesis of model compounds synthesis and proposed cure products, sp{13}C labeling of the ethynyl endgroup in PETI's, monitoring of the thermal cure using solid state sp{13}C NMR and ESR and molecular modeling techniques. Phenylethynyl endcapping agents, 4-(phenylethynyl)phthalic anhydride (PEPA) and 3-(phenylethynyl)aniline (3PEA), were synthesized via the palladium-catalyzed coupling of phenylacetylene with 4-bromophthalic anhydride or 3-iodonitrobenzene followed by reduction to 3PEA, respectively. Isolated yields of 41 and 86% for 3PEA and PEPA were obtained, respectively. Model compounds were synthesized from 3PEA and PEPA by reacting with them the appropriate aniline or phthalic anhydride derivative. Model compounds included N-pentafluorophenyl-4-(phenylethynyl)phthalimide (PEPA/F5An), N-(4-trifluoromethyl-phenyl)4-(phenylethynyl)phthalimide (PEPA/F3CAn), N-lbrack 3-(phenylethynyl)phenylrbrack\\ phthalimide (3PEA/PA), N-phenyl-4-(phenylethynyl)phthalimide (PEPA/An), N-(4-phenoxyphenyl)4-(phenylethynyl)phthalimide (PEPA/POAn), and N-(1-naphthyl)-4-(phenylethynyl)phthalimide (PEPA/Anaph). Proposed cure products such as cyclotrimers and linear oligomers (polyenes) were also synthesized from PEPA/An and analyzed in terms of spectroscopic and thermal properties. The conversion of alpha,beta-sp{13}C-acetophenone to alpha,beta-sp{13}C-phenylacetylene using a LDA/phosphate ester procedure was readily accomplished, and following a silver salt purification, the labeled enylacetylene was immediately reacted with 4-bromophthalic anhydride under Heck coupling conditions. A 29% yield of recrystallized 4-(phenylethynyl-alpha,beta-sp{13}Csb2)phthalic anhydride was obtained based on acetophenone. By adjusting the stoichiometry, sp{13}C labeled phenylethynyl-terminated imide oligomers (PETI) were synthesized with Msb{n} of 2,000 to 9,000 daltons. The thermal curing of PETI's and model compounds was monitored via solid state sp{13}C nuclear magnetic resonance, electron spin resonance spectroscopy and differential scanning calorimetry. Using solid state sp{13}C NMR, several cure products were identified. The effects of post-curing and oligomer chain length on the final structure of the cured resins were also examined. Electron spin resonance spectra were obtained on unlabeled PETI's before and after heating at 250-410sp°C. ESR signals suggest that the curing of these resins involves a carbon centered radical. The cure parameters of model compounds as determined by DSC were tabulated and compared. Molecular mechanics and semi-empirical calculations were employed to calculate theoretical bond orders, ionization potentials, HOMO-LUMO gaps, point charges and molecular volumes. The cure profiles of the model compounds were rationalized using these molecular parameters. All of the present data is consistent with the proposed curing mechanisms and cure products. The dominant factors include the chain length of the reactive oligomer, the backbone structure and steric hindrance around the ethynyl group. Although less defined, the electronics and flexibility around the ethynyl group also appear to be factors in determining the structure of the cured resin. In addition, several relationships between the fina

Roberts, Christopher Chad

1998-11-01

246

Broadband Carbon-13 Correlation Spectra of Microcrystalline Proteins in Very High Magnetic Fields  

E-print Network

spectra with good signal-to-noise ratios.16 Fast spinning, however, suppresses dipolar interactions avoiding excessive sample heating. This opens up new possibilities for efficient dipolar recoupling resonance recoupling under the present experimental conditions, simultaneous magnetization exchange between

247

Sensitivity improvement during heteronuclear spin decoupling in solid-state nuclear magnetic resonance experiments at high spinning frequencies and moderate radio-frequency amplitudes  

NASA Astrophysics Data System (ADS)

Searching for optimal conditions during one- and multi-dimensional solid-state NMR experiments in high static fields may require spinning the sample at frequencies above 40 kHz. This implies challenging requirements for heteronuclear spin decoupling. We have compared the performance of the latest heteronuclear decoupling schemes at high magic-angle spinning frequencies. The results demonstrate that at commonly used rf amplitudes between 80 and 120 kHz, PISSARRO decoupling provides substantial sensitivity improvement. The performance of low-amplitude decoupling at different spinning speeds is also compared and its dependence on the inherent inhomogeneity of the rf field is probed by numerical simulations.

Purusottam, Rudra N.; Bodenhausen, Geoffrey; Tekely, Piotr

2014-10-01

248

Research program in nuclear and solid state physics. [including pion absorption spectra and muon spin precession  

NASA Technical Reports Server (NTRS)

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.

1974-01-01

249

Spin screening effect in superconductor/ferromagnet thin film heterostructures studied using nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

Using NMR spectroscopy of the V51 nuclei in the superconducting state of Ni/V/Ni and Pd1-xFex/V/Pd1-xFex trilayers we reported in a recent letter an experimental observation of the spin screening effect [R. I. Salikhov, I. A. Garifullin, N. N. Garif’yanov, L. R. Tagirov, K. Theis-Bröhl, K. Westerholt, and H. Zabel, Phys. Rev. Lett. 102, 087003 (2009)]. This effect, which designates the formation of a spin polarization in the superconducting state, was predicted previously by Bergeret [F. S. Bergeret, A. F. Volkov, and K. B. Efetov, EPL 66, 111 (2004); Phys. Rev. B 69, 174504 (2004)]. Here, we extend our earlier experiments by varying the thickness of the superconducting V layer and by applying the magnetic field not only perpendicular to the film plane as in the previous experiments, but also in the parallel direction. For the latter geometry, which for experimental reasons is difficult to realize, the film is in the vortex-free state. This allows a direct quantitative comparison of the experimental screening effect as derived from a characteristic distortion of the high-field wing of the resonance line in the superconducting state and the theoretical model calculations. We derive a reasonable agreement between theory and experiment, confirming the spin screening effect in the superconductor.

Salikhov, R. I.; Garif'Yanov, N. N.; Garifullin, I. A.; Tagirov, L. R.; Westerholt, K.; Zabel, H.

2009-12-01

250

Photochemically induced dynamic nuclear polarisation in entire bacterial photosynthetic units observed by 13C magic-angle spinning NMR  

NASA Astrophysics Data System (ADS)

Photochemically induced dynamic nuclear polarisation has been observed from entire photosynthetic units (PSUs) bound to chromatophore membrane (membrane-bound PSU) of the purple bacteria Rhodobacter sphaeroides, which have been selectively 13C-isotope enriched at all BChl and BPheo cofactors. These 1.5 MDa membrane-bound protein complexes comprise reaction centres as well as the antenna systems called light harvesting complexes I and II. Due to light-induced enhancement of nuclear polarisation, the 13C magic-angle spinning (MAS) NMR spectrum shows absorptive lines originating from the cofactors involved into the photochemical machinery and allowing the determination of the electronic ground state structure at atomic resolution. Addition of detergent released intact PSU from the chromatophore membrane (so called detergent solubilised PSU) and caused significant changes in the sign and intensity pattern of the light-induced MAS NMR spectrum. In contrast, detergent solubilised PSU and detergent solubilised bacterial reaction centres with the same isotope label pattern exhibit essentially the same chemical shifts with only minor differences in the intensity pattern. The pronounced differences between intact membrane-bound and detergent solubilised PSU are tentatively explained by the loss of self-orientation of the membrane-bound samples by solubilisation. This interpretation suggests that the theoretically predicted anisotropy of the light-induced nuclear polarisation has been observed for the first time.

Prakash, Shipra; Alia; Gast, Peter; Jeschke, Gunnar; de Groot, Huub J. M.; Matysik, Jörg

2003-12-01

251

A study of the order-disorder, solid-solid phase transition of (+)-camphor using nuclear magnetic resonance with cross-polarization and magic-angle spinning  

E-print Network

A STUDY OF THE ORDER-DISORDER, SOLID-SOLID PHASE TRANSITION OF (+)-CAMPHOR USING NUCLEAR MAGNETIC RESONANCE WITH CROSS-POLARIZATION AND MAGIC-ANGLE SPINNING A Thesis RUSSELL ALLAN CROOK Submitted to the Graduate College of Texas AAM University... in partial fulfillment of the requirement for the degree of MASTER OF SCIENCE AUGUST 1986 Major Subject: Chemistry A STUDY OF THE ORDER-DISORDER, SOLID-SOLID PHASE TRANSITION OF (+)-CAMPHOR USING NUCLEAR MAGNETIC RESONANCE WITH CROSS...

Crook, Russell Allan

2012-06-07

252

The problem of how single electron or hole "central" spins interact with a nuclear spin bath is essential for understanding decoherence  

E-print Network

on passively detecting the spectrum of intrinsic random spin fluctuations while in thermal equilibrium (i noise indicates long (400 ns) spin correlation times at a zero magnetic field that increase to 5 µs and dynamical responses (exponential, power-law, Gaussian, etc.). As an alternative to conventional pump

253

Evolution of nuclear shapes in /sup 157/-/sup 161/Yb as a function of spin and neutron number  

SciTech Connect

The population distributions of the entry states, the entry lines versus multiplicity, the energy spectra and the angular distributions of the continuum ..gamma..-rays as a function of multiplicity in /sup 157/-/sup 161/Yb from the reactions of 136 MeV and 149 MeV /sup 20/Ne with /sup 144/Nd and /sup 146/Nd have been investigated with a 4pi multidetector system gated with a Ge detector. The observed entry lines and ..gamma..-decay modes indicate change for N = 87 - 9l Yb isotopes suggests an evolution of nuclear shapes from prolate at low spins to particle aligned oblate structure for /sup 157/Yb and /sup 158/Yb followed by the onset of high-K bands built on largely deformed oblate states at increasingly higher spin between 38 and 50 n with increasing neutron number for /sup 157/-/sup 161/Yb. Furthermore evidence for an evolution to triaxial shape at I approx. = 50 for /sup 158/Yb was found. 23 references.

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

1982-01-01

254

Transverse nuclear spin relaxation due to director fluctuations in liquid crystals. II. Second-order contributions of the fluctuating director  

NASA Astrophysics Data System (ADS)

Recently, we have introduced a slow-motional theory for transverse nuclear spin relaxation due to director fluctuations [D. Frezzato, G. Kothe, and G. J. Moro, J. Phys. Chem. B 105, 1281 (2001)]. This method is now generalized to second-order contributions of the fluctuating director. We consider the specific case in which the director is aligned orthogonal to the magnetic field. By exploiting the Gaussian character of director fluctuations, the stochastic Liouville equation for the coupled spin and director dynamics is solved in terms of a characteristic function whose time dependence is determined by a nonlinear integral equation. A convenient solution of the integral equation is obtained by decomposing the characteristic function according to the relaxation rates of the director fluctuations. In a first application, we evaluate the free induction decay and the corresponding absorption spectrum for quadrupolar probe nuclei in nematic liquid crystals. It is shown that the transverse magnetization is well represented by a monoexponential decay, i.e., a Lorentzian lineshape in the frequency domain. Explicit relations are derived for the linewidths and frequency shifts under slow-motional conditions where the Redfield theory cannot be applied anymore.

Frezzato, Diego; Moro, Giorgio J.; Kothe, Gerd

2003-10-01

255

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)

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.

Chang, Zhiwei; Halle, Bertil

2013-10-01

256

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

NASA Astrophysics Data System (ADS)

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.

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

2011-01-01

257

Nuclear magnetic relaxation induced by exchange-mediated orientational randomization: longitudinal relaxation dispersion for spin I = 1.  

PubMed

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 (1)H and (2)H 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 (2)H 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 (2)H. 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. PMID:22894360

Nilsson, Tomas; Halle, Bertil

2012-08-01

258

Element-sensitive measurement of the hole-nuclear spin interaction in quantum dots  

NASA Astrophysics Data System (ADS)

It has been proposed that valence-band holes can form robust spin qubits owing to their weaker hyperfine coupling compared with electrons. However, it was demonstrated recently that the hole hyperfine interaction is not negligible, although a consistent picture of the mechanism controlling its magnitude is still lacking. Here we address this problem by measuring the hole hyperfine constant independently for each chemical element in InGaAs/GaAs, InP/GaInP and GaAs/AlGaAs quantum dots. Contrary to existing models we find that the hole hyperfine constant has opposite signs for cations and anions and ranges from -15% to +15% relative to that for electrons. We attribute such changes to the competing positive contributions of p-symmetry atomic orbitals and the negative contributions of d-orbitals. These findings yield information on the orbital composition of the valence band and enable a fundamentally new approach for verification of computed Bloch wavefunctions in semiconductor nanostructures. Furthermore, we show that the contribution of cationic d-orbitals leads to a new mechanism of hole spin decoherence.

Chekhovich, E. A.; Glazov, M. M.; Krysa, A. B.; Hopkinson, M.; Senellart, P.; Lemaître, A.; Skolnick, M. S.; Tartakovskii, A. I.

2013-02-01

259

Applications of carbon-13 and sodium-23 NMR in the study of plants, animal, and human cells  

SciTech Connect

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.

Sillerud, L.O.; Heyser, J.W.; Han, C.H.; Bitensky, M.W.

1984-01-01

260

Reconstriction of atmospheric carbon dioxide and isotopic carbon-13 dioxide from air occluded in ice cores from Greenland and Antarctica  

Microsoft Academic Search

Carbon dioxide (COâ) dioxide (COâ) mixing ratio and isotopic carbon-13 dioxide δ¹³COâ 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 COâ changes during periods of different climatic conditions and to gain insight into the mechanisms

Wahlen

1994-01-01

261

Nuclear Jacobi and Poincar\\'e Transitions at High Spins and Temperatures: Account~of~Dynamic~Effects~and~Large-Amplitude Motion  

E-print Network

We present a theoretical analysis of the competition between so-called nuclear Jacobi and Poincar\\'e shape transitions in function of spin - at high temperatures. The latter condition implies the method of choice - a realistic version of the nuclear Liquid Drop Model (LDM), here: the Lublin-Strasbourg Drop (LSD) model. We address specifically the fact that the Jacobi and Poincar\\'e shape transitions are accompanied by the flattening of total nuclear energy landscape as function of the relevant deformation parameters what enforces large amplitude oscillation modes that need to be taken into account. For that purpose we introduce an approximate form of the collective Schr\\"odinger equation whose solutions are used to calculate the most probable deformations associated with both types of transitions and discuss the physical consequences in terms of the associated critical-spin values and transitions themselves.

Mazurek, K; Maj, A; Rouvel, D

2013-01-01

262

Search of non-standard strong gravity at nuclear scale using electron spin geodetic precession  

NASA Astrophysics Data System (ADS)

The MTV-G project was started in 2011 to explore a strong gravitational field at a nuclear scale in an electron double scattering experiment, utilizing an experimental technique of the MTV experiment, which searches a electron's T-Violating transverse polarization in nuclear beta decay at TRIUMF-ISAC. In addition to this new experiment, we have also performed a re-analysis of spectroscopic data of exotic atoms, in a gravitational point of view. From these two studies, we set new constraints on possible new Yukawa interaction at sub-mm scale, as a test of gravitational inverse square law.

Tanaka, Saki; Nakaya, Yusuke; Narikawa, Reiya; Ninomiya, Kazufumi; Onishi, Junichi; Pearson, Matthew; Openshaw, Robert; Saiba, Shuntaro; Tanuma, Ryosuke; Totsuka, Yumi; Murata, Jiro

2014-03-01

263

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)

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.

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

2007-02-01

264

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

NASA Astrophysics Data System (ADS)

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.

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

2013-03-01

265

Effect of nuclear spin on chemical reactions and internal molecular rotation  

SciTech Connect

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.

Sterna, L.L.

1980-12-01

266

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

PubMed Central

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

Masucci, L; Blackhouse, G; Goeree, R

2013-01-01

267

Very long nuclear relaxation times of spin polarized helium 3 in metal coated cells  

Microsoft Academic Search

We obtained very long relaxation times T1 of up to 120 h for the nuclear polarization of an optically pumped helium 3 gas. The glass containers were internally coated with metallic films such as bismuth or cesium. These findings will have applications in the field of helium magnetometers and polarized targets.

Werner Heil; Hubert Humblot; Ernst Otten; Matthias Schafer; Reinhard Sarkau; Michèle Leduc

1995-01-01

268

Observation of Optical Chemical Shift by Precision Nuclear Spin Optical Rotation Measurements and Calculations  

E-print Network

and Calculations Junhui Shi, Suvi Ikalainen, Juha Vaara,¶ and Michael V. Romalis*,§ Department of Chemistry The rotation of light polarization is similar to the Faraday effect caused by a nuclear magnetic field to Faraday rotation changes by more than a factor of 2 for the simple chemicals studied. We apply the recent

Romalis, Mike

269

Solid-State Dynamic Nuclear Polarization at 263 GHz: Spectrometer Design and Experimental Results  

E-print Network

Dynamic Nuclear Polarization (DNP) experiments transfer polarization from electron spins to nuclear spins with microwave irradiation of the electron spins for enhanced sensitivity in nuclear magnetic resonance (NMR) ...

Rosay, Melanie

270

Contribution of the spin-exchange effects to the nuclear magnetic moments  

Microsoft Academic Search

Summary  The various contributions to the deviations from the Schmidt values of the experimental nuclear magnetic moments are examined.\\u000a The exchange effects are taken in particular consideration and, having selected a particular form for these contributions,\\u000a an explicit expression of this form is given. The magnitude of the unknown function which appears in this expression is fitted\\u000a to the experimental data.

F. Demichelis; F. Iachello

1966-01-01

271

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

SciTech Connect

We show that dynamic nuclear polarization (DNP) can be used to enhance NMR signals of 13C and 29Si nuclei located in mesoporous organic/inorganic hybrid materials, at several hundreds of nanometers from stable radicals (TOTAPOL) trapped in the surrounding frozen disordered water. The approach is demonstrated using mesoporous silica nanoparticles (MSN), functionalized with 3-(N-phenylureido)propyl (PUP) groups, filled with the surfactant cetyltrimethylammonium bromide (CTAB). The DNP-enhanced proton magnetization is transported into the mesopores via 1H–1H spin diffusion and transferred to rare spins by cross-polarization, yielding signal enhancements ?on/off of around 8. When the CTAB molecules are extracted, so that the radicals can enter the mesopores, the enhancements increase to ?on/off ? 30 for both nuclei. A quantitative analysis of the signal enhancements in MSN with and without surfactant is based on a one-dimensional proton spin diffusion model. The effect of solvent deuteration is also investigated.

Lafon, Olivier [Universite de Lille Nord de France; Thankamony, Aany S. Lilly [Universite de Lille Nord de France; Kokayashi, Takeshi [Ames Laboratory; Carnevale, Diego [Ecole Polytechnique Federale de Lausanne; Vitzthum, Veronika [Ecole Polytechnique Federale de Lausanne; Slowing, Igor I. [Ames Laboratory; Kandel, Kapil [Ames Laboratory; Vezin, Herve [Universite de Lille Nord de France; Amoureux, Jean-Paul [Universite de Lille Nord de France; Bodenhausen, Geoffrey [Ecole Polytechnique Federale de Lausanne; Pruski, Marek [Ames Laboratory

2012-12-21

272

Simulations of the (1)H electron spin echo-electron nuclear double resonance and (2)H electron spin echo envelope modulation spectra of exchangeable hydrogen nuclei coupled to the S(2)-state photosystem II manganese cluster.  

PubMed Central

The pulsed EPR methods of electron spin echo envelope modulation (ESEEM) and electron spin echo-electron nuclear double resonance (ESE-ENDOR) are used to investigate the proximity of exchangeable hydrogens around the paramagnetic S(2)-state Mn cluster of the photosystem II oxygen-evolving complex. Although ESEEM and ESE-ENDOR are both pulsed electron paramagnetic resonance techniques, the specific mechanisms by which nuclear spin transitions are observed are quite different. We are able to generate good simulations of both (1)H ESE-ENDOR and (2)H ESEEM signatures of exchangeable hydrogens at the S(2)-state cluster. The convergence of simulation parameters for both methods provides a high degree of confidence in the simulations. Several exchangeable protons-deuterons with strong dipolar couplings are observed. In the simulations, two of the close ( approximately 2.5 A) hydrogen nuclei exhibit strong isotropic couplings and are therefore most probably associated with direct substrate ligation to paramagnetic Mn. Another two of the close ( approximately 2.7 A) hydrogen nuclei show no isotropic couplings and are therefore most probably not contained in Mn ligands. We suggest that these proximal hydrogens may be associated with a Ca(2+)-bound substrate, as indicated in recent mechanistic proposals for O(2) formation. PMID:12437874

Aznar, Constantino P; Britt, R David

2002-01-01

273

Using bio-functionalized magnetic nanoparticles and dynamic nuclear magnetic resonance to characterize the time-dependent spin-spin relaxation time for sensitive bio-detection.  

PubMed

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

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

274

THE LOW-TEMPERATURE NUCLEAR SPIN EQUILIBRIUM OF H{sup +} {sub 3} IN COLLISIONS WITH H{sub 2}  

SciTech Connect

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.

Grussie, F.; Berg, M. H.; Wolf, A.; Kreckel, H. [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, D-69117 Heidelberg (Germany); Crabtree, K. N.; McCall, B. J. [Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, IL 61801 (United States); Gaertner, S.; Schlemmer, S., E-mail: holger.kreckel@mpi-hd.mpg.de [I. Physikalisches Institut, Universitaet zu Koeln, Zuelpicher Str. 77, D-50937 Koeln (Germany)

2012-11-01

275

Quenching of the magnetic multipole strength distribution and of the anomalous magnetic moment in complex nuclei and mesonic renormalization of the nuclear spin current  

Microsoft Academic Search

The retardation of the magnetic multipole strength distribution (specifically M1 and M2) extracted from inelastic electron scattering to so-called pion-like states and the quenching of magnetic moments, both in heavy nuclei, is attributed to a mesonic renormalization of the nuclear spin current. The mechanism invoked is the same that leads to the renormalization of the axial current in nuclei and

W. Knüpfer; M. Dillig; A. Richter

1980-01-01

276

Near-Surface Structural Phase Transition of SrTiO3 Studied with Zero-Field ?-Detected Nuclear Spin Relaxation and Resonance  

NASA Astrophysics Data System (ADS)

We demonstrate that zero-field ?-detected nuclear quadrupole resonance and spin relaxation of low energy Li8 can be used as a sensitive local probe of structural phase transitions near a surface. We find that the transition near the surface of a SrTiO3 single crystal occurs at Tc˜150K, i.e., ˜45K higher than Tcbulk, and that the tetragonal domains formed below Tc are randomly oriented.

Salman, Z.; Kiefl, R. F.; Chow, K. H.; Hossain, M. D.; Keeler, T. A.; Kreitzman, S. R.; Levy, C. D. P.; Miller, R. I.; Parolin, T. J.; Pearson, M. R.; Saadaoui, H.; Schultz, J. D.; Smadella, M.; Wang, D.; Macfarlane, W. A.

2006-04-01

277

Nuclear magnetic resonance data of CF3I  

NASA Astrophysics Data System (ADS)

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

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

278

Effects of strain and quantum confinement in optically pumped nuclear magnetic resonance in GaAs: Interpretation guided by spin-dependent band structure calculations  

NASA Astrophysics Data System (ADS)

A combined experimental-theoretical study of optically pumped nuclear magnetic resonance (OPNMR) has been performed in a GaAs /A l0.1G a0.9As quantum well film epoxy bonded to a Si substrate with thermally induced biaxial strain. The photon energy dependence of the Ga 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 the electronic structure and differential absorption to spin-up and spin-down states of the electron conduction band using a modified k .p model based on the Pidgeon-Brown model. Comparison of theory with experiment facilitated the assignment of features in the OPNMR energy dependence to specific interband Landau level transitions. The results provide insight into how effects of strain and quantum confinement are manifested in optical nuclear polarization in semiconductors.

Wood, R. M.; Saha, D.; McCarthy, L. A.; Tokarski, J. T.; Sanders, G. D.; Kuhns, P. L.; McGill, S. A.; Reyes, A. P.; Reno, J. L.; Stanton, C. J.; Bowers, C. R.

2014-10-01

279

Relaxation magnétique nucléaire du carbone-13 et dynamique des molécules de chlorpromazine associées en solution aqueuse  

NASA Astrophysics Data System (ADS)

13C relaxation times and heteronuclear NOE enhancements have been measured for chlorpromazine hydrochloride salt in chloroform and water. The dipolar contribution to 13C ^1H spin systems relaxation rates were extracted and allowed us to characterize the molecular reorientation in the two solvents. The correlation times are on either side of “T1 minimum". The values agree with the size of the molecule and show an association by stacking of 11 monomeric entities. Les temps de relaxation des 13C et les accroissements par effet Overhauser 1Hto13C ont été mesurés parallèlement sur la molécule de chlorhydrate de chlorpromazine non associée dans le chloroforme et auto-associée dans l'eau. L'extraction de la contribution dipolaire aux constantes de vitesse de relaxation des systèmes 13C 1H de la molécule a permis de caractériser la réorientation de la molécule dans les deux cas. Les temps de corrélation obtenus qui se situent de part et d'autre du “T1 minimum" sont en accord avec la taille de la molécule isolée et montrent que l'agrégat est formé par empilement de 11 molécules.

Compère, S.; Thévand, A.

1998-02-01

280

A nuclear magnetic resonance spectrometer concept for hermetically sealed magic angle spinning investigations on highly toxic, radiotoxic, or air sensitive materials.  

PubMed

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 (Th(1-x)U(x))O2 solid solutions gives rise to extensive spinning sidebands and poor resolution at 15 kHz, which is dramatically improved at 55 kHz. The first (17)O MAS-NMR measurements on NpO(2+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. PMID:23742594

Martel, L; Somers, J; Berkmann, C; Koepp, F; Rothermel, A; Pauvert, O; Selfslag, C; Farnan, I

2013-05-01

281

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)

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.

Baek, S.-H.; Klingeler, R.; Neef, C.; Koo, C.; Büchner, B.; Grafe, H.-J.

2014-04-01

282

Anomalous enrichment of {sup 17}O and {sup 13}C in photodissociation products of CO{sub 2}: Possible role of nuclear spin  

SciTech Connect

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.

Mahata, Sasadhar; Bhattacharya, S. K. [Physical Research Laboratory, Navrangpura, Ahmedabad 380 009 (India)

2009-06-21

283

Twelve-spin "Schrodinger cat"  

E-print Network

Pseudopure "cat" state, a superposition of quantum states with all spins up and all spins down, is experimentally demonstrated for a system of twelve dipolar-coupled nuclear spins of fully 13C-labeled benzene molecule oriented in a liquid-crystalline matrix.

Jae-Seung Lee; A. K. Khitrin

2005-08-01

284

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...

285

Wheat bran biodegradation by Pleurotus ostreatus: a solid-state carbon-13 NMR study.  

PubMed

Solid-state (13)C nuclear magnetic resonance (NMR) and elemental analysis techniques were used to monitor the degradation of wheat bran by the white-rot fungus Pleurotus ostreatus during a 62-day cultivation period. The weight loss and in vitro organic matter digestibility of the substrate were also evaluated after fungal treatment. The (13)C NMR spectra of degraded wheat bran samples showed a lower content in carbohydrates and a higher content in aliphatic and carboxylic groups than the untreated control sample. In parallel, changes in the wheat bran elemental composition evidenced a decrease in carbon content and a concomitant increase in nitrogen and oxygen content during mycelium growth. These results clearly indicate the occurrence of progressive changes in the composition of wheat bran during fungal treatment and are interpreted in terms of preferential degradation of amorphous vs. crystalline polysaccharides by the fungal mycelium and accumulation of proteins in the substrate. At the end of the cultivation period, the treated samples experienced an average weight loss of 20% and an increase in organic matter digestibility of 17%. PMID:17920878

Locci, Emanuela; Laconi, Samuela; Pompei, Raffaello; Scano, Paola; Lai, Adolfo; Marincola, Flaminia Cesare

2008-07-01

286

13C-13C Homonuclear Recoupling in Solid-State Nuclear Magnetic Resonance at a Moderately High Magic-Angle-Spinning Frequency  

PubMed Central

Two-dimensional 13C-13C correlation experiments are widely employed in structure determination of protein assemblies using solid-state nuclear magnetic resonance. Here, we investigate the process of 13C-13C magnetisation transfer at a moderate magic-angle-spinning frequency of 30 kHz using some of the prominent second-order dipolar recoupling schemes. The effect of isotropic chemical-shift difference and spatial distance between two carbons and amplitude of radio frequency on 1H channel on the magnetisation transfer efficiency of these schemes is discussed in detail. PMID:23326308

Mithu, Venus Singh; Bakthavatsalam, Subha; Madhu, Perunthiruthy K.

2013-01-01

287

Spin-noise correlations and spin-noise exchange driven by low-field spin-exchange collisions  

NASA Astrophysics Data System (ADS)

The physics of spin-exchange collisions have fueled several discoveries in fundamental physics and numerous applications in medical imaging and nuclear magnetic resonance. We report on the experimental observation and theoretical justification of spin-noise exchange, the transfer of spin noise from one atomic species to another. The signature of spin-noise exchange is an increase of the total spin-noise power at low magnetic fields, on the order of 1 mG, where the two-species spin-noise resonances overlap. The underlying physical mechanism is the two-species spin-noise correlation induced by spin-exchange collisions.

Dellis, A. T.; Loulakis, M.; Kominis, I. K.

2014-09-01

288

Nuclear magnetic resonance data of C15H23AsS2  

NASA Astrophysics Data System (ADS)

This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

Mikhova, B. M.

289

Nuclear magnetic resonance data of C16H25AsS3  

NASA Astrophysics Data System (ADS)

This document is part of Part 6 `Organic Metalloid Compounds' of Subvolume D 'Chemical Shifts and Coupling Constants for Carbon-13' of Landolt-Börnstein III/35 'Nuclear Magnetic Resonance Data', Group III 'Condensed Matter'.

Mikhova, B. M.

290

A simple nuclear-style mean field absorption/spin-orbit model for the Sivers function of the nucleon  

E-print Network

I study the effect of scalar and spin-orbit absorption potentials, in the production of a nonzero Sivers-like asymmetry in hadron-hadron high energy collisions (Drell-Yan and single spin asymmetries). A basic model is built for the intrinsic state of a quark in the projectile hadron. S-wave and P-wave 2-component states are considered. Before the hard event, this quark is subject to absorbing scalar and spin-orbit local mean fields simulating interactions with a composite target. The relevant interaction terms are found to be the imaginary diagonal spin-orbit ones. Spin rotating terms, and scalar absorption, are not decisive. For $x$ $=$ 0 the found Sivers asymmetry vanishes, while at larger $x$ its qualitative dependence on $x$, $K_T$ follows the usual trends met in available models and parameterizations. Given the present-day knowledge of the considered phenomenological interactions, it is not possible to establish whether the related Sivers-like asymmetry is a leading twist one.

Andrea Bianconi

2007-02-19

291

Structural characterization of AlON by {sup 27}Al MAS NMR and quantum chemistry method[Magic-Angle Spinning Nuclear Magnetic Resonance  

SciTech Connect

Aluminum oxynitride (AlON) is a nitrogen-stabilized defective spinel phase of alumina ({gamma}-Al{sub 2}{sub 3}). Its structure has not been well understood so far. Solid-state {sup 27}Al magic-angle spinning nuclear magnetic resonance and quantum chemistry calculation are used to characterize {gamma}-Al{sub 2}O{sub 3} and AlON ceramics in the present study. The resonance spectra clearly show different units (e.g., [AlN{sub 4}], [AlO{sub 4}] and [AlO{sub 6}]) and vary with composition. The calculation shows that the vacancy located at octahedral site is more stable than that located at the tetrahedral site, and nitrogen atoms preferentially replace oxygen atoms in the tetrahedral site, which is in agreement with the experimental analysis by nuclear magnetic resonance.

Dai, Y.; Min, X.M.; Nan, C.W.; Pei, X.M.; Ren, H.L.

1999-07-01

292

Nuclear quadrupole spin-lattice relaxation in Bi{sub 4}Ge{sub 3}O{sub 12} single crystals doped with atoms of d or f elements. Crystal field effects in compounds exhibiting anomalous magnetic properties  

SciTech Connect

The nuclear quadrupole spin-lattice relaxation was studied in the range 4.2-300 K for single crystals of Bi{sub 4}Ge{sub 3}O{sub 12} doped with minor amounts (the tenth fractions of mol%) of paramagnetic atoms of Cr, Nd, and Gd. Unusual spin dynamic features were recently found for these crystals at room temperature: a dramatic (up to 8-fold) increase in the effective nuclear quadrupole spin-spin relaxation time T{sub 2}* occurred upon doping the pure Bi{sub 4}Ge{sub 3}O{sub 12} sample. Unlike T{sub 2}*, the effective spin-lattice relaxation time T{sub 1}* at room temperature differs insignificantly for both doped and pure samples. But at lower temperatures, the samples exhibit considerably different behavior of the spin-lattice relaxation with temperature, which is caused by different contributions to the relaxation process of the dopant paramagnetic atoms. The distinctive maximum in the temperature dependence of the spin-lattice relaxation time for the Nd-doped crystal is shown to result from the crystal electric field effects.

Orlov, V. G., E-mail: orlov@mbslab.kiae.ru; Sergeev, G. S. [Russian Research Center 'Kurchatov Institute' (Russian Federation); Asaji, Tetsuo [Nihon University, Department of Chemistry, College of Humanities and Sciences (Japan); Kravchenko, E. A. [Russian Academy of Sciences, Institute of General and Inorganic Chemistry (Russian Federation); Kargin, Yu. F. [Russian Academy of Sciences, State Institute of Metallurgy and Material Science (Russian Federation)

2010-02-15

293

Salinity-induced Patterns of Natural Abundance Carbon-13 and Nitrogen-15 in Plant Jan-Willem van Groenigen* and Chris van Kessel  

E-print Network

might be because (Guy et al., 1986a and 1986b). Along a soil water poten- of higher NH3 volatilizationSalinity-induced Patterns of Natural Abundance Carbon-13 and Nitrogen-15 in Plant and Soil Jan-Willem van Groenigen* and Chris van Kessel ABSTRACT vs. C4 ), age of SOM, depth in the profile

van Kessel, Chris

294

Generalized spin precession equations  

NASA Astrophysics Data System (ADS)

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.

Stöckmann, Hans-Jürgen; Dubbers, Dirk

2014-05-01

295

Nucleon-nucleon spin dependent scattering amplitudes to describe final state interactions in electromagnetic and electroweak nuclear processes  

NASA Astrophysics Data System (ADS)

There are currently no models readily available that provide nucleon-nucleon spin dependent scattering amplitudes at high energies ( s ? 6 GeV2). This work aims to provide a model for calculating these high-energy scattering amplitudes. The foundation of the model is Regge theory since it allows for a relativistic description and full spin dependence. A parameterization of the amplitudes is presented. and comparisons of the solution to the assembled data set are shown. In addition, an application of the model to describe final state interactions in deuteron electrodisintegration is presented. Overall the model works as intended, and provides an adequate description of the nucleon-nucleon interaction at these energies.

Ford, William P.

296

Electrical and ionic conductivity effects on magic-angle spinning nuclear magnetic resonance parameters of CuI  

NASA Astrophysics Data System (ADS)

We investigate experimentally and theoretically the effects of two different types of conductivity, electrical and ionic, upon magic-angle spinning NMR spectra. The experimental demonstration of these effects involves 63Cu, 65Cu, and 127I variable temperature MAS-NMR experiments on samples of ?-CuI, a Cu+-ion conductor at elevated temperatures as well as a wide bandgap semiconductor. We extend previous observations that the chemical shifts depend very strongly upon the square of the spinning-speed as well as the particular sample studied and the magnetic field strength. By using the 207Pb resonance of lead nitrate mixed with the ?-CuI as an internal chemical shift thermometer we show that frictional heating effects of the rotor do not account for the observations. Instead, we find that spinning bulk CuI, a p-type semiconductor due to Cu+ vacancies in nonstoichiometric samples, in a magnetic field generates induced AC electric currents from the Lorentz force that can resistively heat the sample by over 200 °C. These induced currents oscillate along the rotor spinning axis at the spinning speed. Their associated heating effects are disrupted in samples containing inert filler material, indicating the existence of macroscopic current pathways between micron-sized crystallites. Accurate measurements of the temperature-dependence of the 63Cu and 127I chemical shifts in such diluted samples reveal that they are of similar magnitude (ca. 0.27 ppm/K) but opposite sign (being negative for 63Cu), and appear to depend slightly upon the particular sample. This relationship is identical to the corresponding slopes of the chemical shifts versus square of the spinning speed, again consistent with sample heating as the source of the observed large shift changes. Higher drive-gas pressures are required to spin samples that have higher effective electrical conductivities, indicating the presence of a braking effect arising from the induced currents produced by rotating a conductor in a homogeneous magnetic field. We present a theoretical analysis and finite-element simulations that account for the magnitude and rapid time-scale of the resistive heating effects and the quadratic spinning speed dependence of the chemical shift observed experimentally. Known thermophysical properties are used as inputs to the model, the sole adjustable parameter being a scaling of the bulk thermal conductivity of CuI in order to account for the effective thermal conductivity of the rotating powdered sample. In addition to the dramatic consequences of electrical conductivity in the sample, ionic conductivity also influences the spectra. All three nuclei exhibit quadrupolar satellite transitions extending over several hundred kilohertz that reflect defects perturbing the cubic symmetry of the zincblende lattice. Broadening of these satellite transitions with increasing temperature arises from the onset of Cu+ ion jumps to sites with different electric field gradients, a process that interferes with the formation of rotational echoes. This broadening has been quantitatively analyzed for the 63Cu and 65Cu nuclei using a simple model in the literature to yield an activation barrier of 0.64 eV (61.7 kJ/mole) for the Cu+ ion jumping motion responsible for the ionic conductivity that agrees with earlier results based on 63Cu NMR relaxation times of static samples

Yesinowski, James P.; Ladouceur, Harold D.; Purdy, Andrew P.; Miller, Joel B.

2010-12-01

297

Leading Edge Spinning the Web of Cell Fate  

E-print Network

Leading Edge Minireview Spinning the Web of Cell Fate Kevin Van Bortle1 and Victor G. Corces1,* 1 involved in spinning the web of cell fate. Chromatin at the Nuclear Lamina The nuclear lamina is a thin

Corces, Victor G.

298

Spatial and Temporal Variations in Stable Carbon (?13C) and Nitrogen (?15N) Isotopic Composition of Symbiotic Scleractinian Corals  

PubMed Central

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

Nahon, Sarah; Richoux, Nicole B.; Kolasinski, Joanna; Desmalades, Martin; Ferrier Pages, Christine; Lecellier, Gael; Planes, Serge; Berteaux Lecellier, Veronique

2013-01-01

299

Reconstriction of atmospheric carbon dioxide and isotopic carbon-13 dioxide from air occluded in ice cores from Greenland and Antarctica  

SciTech Connect

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.

Wahlen, M. [Univ. of California, La Jolla, CA (United States)

1994-12-31

300

Nuclear spins, magnetic moments, and quadrupole moments of Cu isotopes from N=28 to N=46: Probes for core polarization effects  

SciTech Connect

Measurements of the ground-state nuclear spins and magnetic and quadrupole moments of the copper isotopes from {sup 61}Cu up to {sup 75}Cu are reported. The experiments were performed at the CERN online isotope mass separator (ISOLDE) facility, using the technique of collinear laser spectroscopy. The trend in the magnetic moments between the N=28 and N=50 shell closures is reasonably reproduced by large-scale shell-model calculations starting from a {sup 56}Ni core. The quadrupole moments reveal a strong polarization of the underlying Ni core when the neutron shell is opened, which is, however, strongly reduced at N=40 due to the parity change between the pf and g orbits. No enhanced core polarization is seen beyond N=40. Deviations between measured and calculated moments are attributed to the softness of the {sup 56}Ni core and weakening of the Z=28 and N=28 shell gaps.

Vingerhoets, P.; Avgoulea, M.; Bissell, M. L.; De Rydt, M.; Neyens, G. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, B-3001 Leuven (Belgium); Flanagan, K. T. [Instituut voor Kern- en Stralingsfysica, K.U. Leuven, B-3001 Leuven (Belgium); IPN Orsay, F-91940 Orsay Cedex (France); Billowes, J.; Cheal, B.; Mane, E. [School of Physics and Astronomy, The University of Manchester, Manchester M13 9PL (United Kingdom); Blaum, K.; Schug, M. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Brown, B. A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Forest, D. H.; Tungate, G. [School of Physics and Astronomy, The University of Birmingham, Birmingham B15 2TT (United Kingdom); Geppert, Ch.; Noertershaeuser, W. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Institut fuer Kernchemie, Johannes Gutenberg-Universitaet Mainz, D-55128 Mainz (Germany); Honma, M. [Center for Mathematical Sciences, University of Aizu, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Kowalska, M. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Kraemer, J.; Krieger, A. [Institut fuer Kernchemie, Johannes Gutenberg-Universitaet Mainz, D-55128 Mainz (Germany)

2010-12-15

301

Towards real-time metabolic profiling of a biopsy specimen during a surgical operation by 1H high resolution magic angle spinning nuclear magnetic resonance: a case report  

PubMed Central

Introduction Providing information on cancerous tissue samples during a surgical operation can help surgeons delineate the limits of a tumoral invasion more reliably. Here, we describe the use of metabolic profiling of a colon biopsy specimen by high resolution magic angle spinning nuclear magnetic resonance spectroscopy to evaluate tumoral invasion during a simulated surgical operation. Case presentation Biopsy specimens (n = 9) originating from the excised right colon of a 66-year-old Caucasian women with an adenocarcinoma were automatically analyzed using a previously built statistical model. Conclusions Metabolic profiling results were in full agreement with those of a histopathological analysis. The time-response of the technique is sufficiently fast for it to be used effectively during a real operation (17 min/sample). Metabolic profiling has the potential to become a method to rapidly characterize cancerous biopsies in the operation theater. PMID:22257563

2012-01-01

302

Geometrical spin symmetry and spin  

SciTech Connect

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.

Pestov, I. B., E-mail: pestov@theor.jinr.ru [Joint Institute for Nuclear Research (Russian Federation)

2011-07-15

303

Theory of the spin bath  

Microsoft Academic Search

The quantum dynamics of mesoscopic or macroscopic systems is always complicated by their coupling to many `environmental' modes. At low T these environmental effects are dominated by localized modes, such as nuclear and paramagnetic spins, and defects (which also dominate the entropy and specific heat). This environment, at low energies, maps onto a `spin bath' model. This contrasts with `oscillator

N V Prokofev; Philip Stamp

2000-01-01

304

Theory of the spin bath  

Microsoft Academic Search

The quantum dynamics of mesoscopic or macroscopic systems is always complicated by their coupling to many 'environmental' modes. At low T these environmental effects are dominated by localized modes, such as nuclear and paramagnetic spins, and defects (which also dominate the entropy and specific heat). This environment, at low energies, maps onto a 'spin bath' model. This contrasts with 'oscillator

305

Two-dimensional RF pulses: A new approach to selectively exciting J-coupled spins in nuclear magnetic resonance  

NASA Astrophysics Data System (ADS)

A new scheme for the excitation of spins according to the joint values of their heteronuclear or homonuclear J couplings and of their chemical shifts, is proposed and demonstrated. The principles of the new pulses involved derive from those employed in NMR imaging for exciting arbitrary 2D spatial shapes, using so-called "multidimensional" RF pulses. It is shown that if recast in a suitable spectroscopic framework, the distinction that ?-pulses enable to establish between linear and bilinear interactions, support the selective excitation of coherences possessing arbitrary combinations of chemical shift and J-coupling values - a flexibility akin to that provided by a 2D J-resolved NMR spectrum. Details on the execution of the resulting 2D "J-shift" RF pulses are given, and examples where excitation only addresses spins with particular chemical shift offsets fulfilling specific J-coupling displacements, are demonstrated. Additional instances where such pulses could be applied, as well as main limitations of this new approach, are briefly discussed.

Lupulescu, Adonis; Aharon, Hannah; Frydman, Lucio

2013-10-01

306

Spin echoes of nuclear magnetization diffusing in a constant magnetic field gradient and in a restricted geometry  

SciTech Connect

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.}

Sen, P.N. [Schlumberger-Doll Research, Old Quarry Road, Ridgefield, Connecticut 06877-4108 (United States)] [Schlumberger-Doll Research, Old Quarry Road, Ridgefield, Connecticut 06877-4108 (United States); Andre, A. [Schlumberger-Doll Research, Old Quarry Road, Ridgefield, Connecticut 06877-4108 (United States)] [Schlumberger-Doll Research, Old Quarry Road, Ridgefield, Connecticut 06877-4108 (United States); [Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Axelrod, S. [Schlumberger-Doll Research, Old Quarry Road, Ridgefield, Connecticut 06877-4108 (United States)] [Schlumberger-Doll Research, Old Quarry Road, Ridgefield, Connecticut 06877-4108 (United States); [Department of Mathematics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02138 (United States)

1999-10-01

307

Nuclear Spins and Moments of Ga Isotopes Reveal Sudden Structural Changes between N=40 and N=50  

SciTech Connect

Collinear laser spectroscopy was performed on Ga (Z=31) isotopes at ISOLDE, CERN. A gas-filled linear Paul trap (ISCOOL) was used to extend measurements towards very neutron-rich isotopes (N=36-50). A ground state (g.s.) spin I=1/2 is measured for {sup 73}Ga, being near degenerate with a 3/2{sup -} isomer (75 eV < or approx. E{sub ex} < or approx. 1 keV). The {sup 79}Ga g.s., with I=3/2, is dominated by protons in the {pi}f{sub 5/2} orbital and in {sup 81}Ga the 5/2{sup -} level becomes the g.s. The data are compared to shell-model calculations in the f{sub 5/2}pg{sub 9/2} model space, calling for further theoretical developments and new experiments.

Cheal, B.; Mane, E.; Billowes, J.; Charlwood, F. C. [School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Bissell, M. L.; Neyens, G.; Vingerhoets, P. [Instituut voor Kern- en Stralingsfysica, Katholieke Universiteit Leuven, B-3001 Leuven (Belgium); Blaum, K.; Schug, M.; Yordanov, D. T. [Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Brown, B. A. [National Superconducting Cyclotron Laboratory and Department of Physics and Astronomy, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Flanagan, K. T. [I.P.N. Orsay, F-91940 Orsay Cedex (France); Forest, D. H. [School of Physics and Astronomy, The University of Birmingham, Birmingham, B15 2TT (United Kingdom); Geppert, C.; Noertershaeuser, W. [GSI Helmholtzzentrum fuer Schwerionenforschung GmbH, D-64291 Darmstadt (Germany); Institut fuer Kernchemie, Universitaet Mainz, D-55128 Mainz (Germany); Honma, M. [Center for Mathematical Sciences, University of Aizu, Tsuruga, Ikki-machi, Aizu-Wakamatsu, Fukushima 965-8580 (Japan); Jokinen, A.; Moore, I. D. [Department of Physics, University of Jyvaeskylae, FIN-40014 Jyvaeskylae (Finland); Helsinki Institute of Physics, FIN-00014, University of Helsinki (Finland); Kowalska, M. [Physics Department, CERN, CH-1211 Geneva 23 (Switzerland); Max-Planck-Institut fuer Kernphysik, D-69117 Heidelberg (Germany); Krieger, A. [Institut fuer Kernchemie, Universitaet Mainz, D-55128 Mainz (Germany)

2010-06-25

308

Nuclear spins and moments of Ga isotopes reveal sudden structural changes between N=40 and N=50.  

PubMed

Collinear laser spectroscopy was performed on Ga (Z=31) isotopes at ISOLDE, CERN. A gas-filled linear Paul trap (ISCOOL) was used to extend measurements towards very neutron-rich isotopes (N=36-50). A ground state (g.s.) spin I=1/2 is measured for 73Ga, being near degenerate with a 3/2{-} isomer (75??eV?E{ex}?1??keV). The 79Ga g.s., with I=3/2, is dominated by protons in the ?f{5/2} orbital and in 81Ga the 5/2{-} level becomes the g.s. The data are compared to shell-model calculations in the f{5/2}pg{9/2} model space, calling for further theoretical developments and new experiments. PMID:20867369

Cheal, B; Mané, E; Billowes, J; Bissell, M L; Blaum, K; Brown, B A; Charlwood, F C; Flanagan, K T; Forest, D H; Geppert, C; Honma, M; Jokinen, A; Kowalska, M; Krieger, A; Krämer, J; Moore, I D; Neugart, R; Neyens, G; Nörtershäuser, W; Schug, M; Stroke, H H; Vingerhoets, P; Yordanov, D T; Záková, M

2010-06-25

309

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)

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.

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

310

Photochemically induced dynamic nuclear polarisation in entire bacterial photosynthetic units observed by 13C magic-angle spinning NMR  

Microsoft Academic Search

Photochemically induced dynamic nuclear polarisation has been observed from entire photosynthetic units (PSUs) bound to chromatophore membrane (membrane-bound PSU) of the purple bacteria Rhodobacter sphaeroides, which have been selectively 13C-isotope enriched at all BChl and BPheo cofactors. These 1.5MDa membrane-bound protein complexes comprise reaction centres as well as the antenna systems called light harvesting complexes I and II. Due to

Shipra Prakash; Alia; Peter Gast; Gunnar Jeschke; Huub J. M. de Groot; Jörg Matysik

2003-01-01

311

Mass effects in the theoretical determination of nuclear-spin relaxation rates for atomic hydrogen and deuterium  

Microsoft Academic Search

The normal method for calculating very precise eigenvalues for H2 and its isotopes is to solve the Schrödinger equation using a reduced mass calculated from the bare nuclear mass with the mass-independent Born-Oppenheimer potentials and with mass-dependent adiabatic and nonadiabatic correction terms that account for the finite mass of the nuclei. On the other hand, scattering calculations have used reduced

Carl J. Williams; Paul S. Julienne

1993-01-01

312

On Spin Fluctuations in Dense Matter and Skyrme Interactions  

SciTech Connect

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.

Sagawa, H.; Margueron, J. [Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, 965-8580 Fukushima (Japan)

2009-05-07

313

Comparison of Nuclear Spin Relaxation of H2O@C60 and H2@C60 and Their Nitroxide Derivatives  

E-print Network

, and increases monotonically with decreasing temperature, implying that T1 is dominated by the spin-rotation molecule to be incorporated into the C60 cage using the molecular surgery methodology and the first are considered below. (1) Spin-lattice relaxation in H2 occurs by both dipole- dipole (dip) and spin-rotation (sr

Turro, Nicholas J.

314

Spin diffusion of dipolar energy in NQR.  

PubMed

The theory of spin diffusion was extended to the case of nuclear dipolar order in solids containing paramagnetic impurities and nuclei with spin I > 1/2 having nuclear quadrupole moment. We show that spin diffusion process of dipolar order takes place in solids containing paramagnetic impurities. At the start of relaxation process, the direct relaxation regime is realized with non-exponential time dependence. Then the relaxation regime will be changed to diffusion-limited one. Using obtained expressions for the spin lattice relaxation times for these two relaxation regimes, the diffusion coefficient of the dipolar order in nuclear quadrupole resonance can be estimated from experimental data. PMID:10868572

Furman, G B; Goren, S D

2000-06-01

315

Spinning angle optical calibration apparatus  

DOEpatents

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.

Beer, Stephen K. (Morgantown, WV); Pratt, II, Harold R. (Morgantown, WV)

1991-01-01

316

Low Energy Nuclear Reaction Cross Sections for a Secondary High-Spin Isomeric Nuclear Beam (^18F^m) in Silicon  

Microsoft Academic Search

A 30 MeV\\/u primary ^17O primary beam has been used to produce a 22.3 MeV\\/u ^18F^m ( J^pi=5^+, E_x=1.1 MeV) isomeric secondary beam via the single nucleon transfer reaction ^17O(^12C,^11B)^18F. The total nuclear reaction cross section for ^18F^m , ^18F_g.s and ^16O in silicon were measured, and will be presented, in an X-Y-DeltaE-E detector telescope consisting of seven thin silicon

D. A. Roberts; F. D. Becchetti; J. Janecke; M. Y. Lee; T. W. O'Donnell; K. Pham; R. E. Warner; R. M. Ronningen; H. W. Wilschut

1996-01-01

317

Nuclear Spin Lattice Relaxation and Conductivity Studies of the Non-Arrhenius Conductivity Behavior in Lithium Fast Ion Conducting Sulfide Glasses  

SciTech Connect

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?

Benjamin Michael Meyer

2003-05-31

318

Nuclear spins and magnetic moments of 71,73,75Cu: inversion of pi2p3/2 and pi1f5/2 levels in 75Cu.  

PubMed

We report the first confirmation of the predicted inversion between the pi2p3/2 and pi1f5/2 nuclear states in the nu(g)9/2 midshell. This was achieved at the ISOLDE facility, by using a combination of in-source laser spectroscopy and collinear laser spectroscopy on the ground states of 71,73,75Cu, which measured the nuclear spin and magnetic moments. The obtained values are mu(71Cu)=+2.2747(8)mu(N), mu(73Cu)=+1.7426(8)mu(N), and mu(75Cu)=+1.0062(13)mu(N) corresponding to spins I=3/2 for 71,73Cu and I=5/2 for 75Cu. The results are in fair agreement with large-scale shell-model calculations. PMID:19905565

Flanagan, K T; Vingerhoets, P; Avgoulea, M; Billowes, J; Bissell, M L; Blaum, K; Cheal, B; De Rydt, M; Fedosseev, V N; Forest, D H; Geppert, Ch; Köster, U; Kowalska, M; Krämer, J; Kratz, K L; Krieger, A; Mané, E; Marsh, B A; Materna, T; Mathieu, L; Molkanov, P L; Neugart, R; Neyens, G; Nörtershäuser, W; Seliverstov, M D; Serot, O; Schug, M; Sjoedin, M A; Stone, J R; Stone, N J; Stroke, H H; Tungate, G; Yordanov, D T; Volkov, Yu M

2009-10-01

319

Initialization and readout of spin chains for quantum information transport  

Microsoft Academic Search

Linear chains of spins acting as quantum wires are a promising approach for achieving scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test bed for the experimental study of quantum information transport, as they closely emulate a one-dimensional spin chain, while magnetic resonance techniques can be used to drive the spin chain dynamics and probe the

Gurneet Kaur; Paola Cappellaro

2012-01-01

320

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

Neutrino emission significantly affects the evolution of the accretion tori formed in black hole-neutron star mergers. It removes energy from the disk, alters its composition, and provides a potential power source for a gamma-ray burst. To study these effects, simulations in general relativity with a hot microphysical equation of state (EOS) and neutrino feedback are needed. We present the first such simulation, using a neutrino leakage scheme for cooling to capture the most essential effects and considering a moderate mass (1.4 M{sub ?} neutron star, 5.6 M{sub ?} black hole), high-spin (black hole J/M {sup 2} = 0.9) system with the K{sub 0} = 220 MeV Lattimer-Swesty EOS. We find that about 0.08 M{sub ?} of nuclear matter is ejected from the system, while another 0.3 M{sub ?} forms a hot, compact accretion disk. The primary effects of the escaping neutrinos are (1) to make the disk much denser and more compact, (2) to cause the average electron fraction Y{sub e} of the disk to rise to about 0.2 and then gradually decrease again, and (3) to gradually cool the disk. The disk is initially hot (T ? 6 MeV) and luminous in neutrinos (L{sub ?} ? 10{sup 54} erg s{sup –1}), but the neutrino luminosity decreases by an order of magnitude over 50 ms of post-merger evolution.

Deaton, M. Brett; Duez, Matthew D. [Department of Physics and Astronomy, Washington State University, Pullman, WA 99164 (United States); Foucart, Francois; O'Connor, Evan [Canadian Institute for Theoretical Astrophysics, University of Toronto, Toronto, Ontario M5S 3H8 (Canada); Ott, Christian D.; Scheel, Mark A.; Szilagyi, Bela [TAPIR, MC 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Kidder, Lawrence E.; Muhlberger, Curran D., E-mail: mbdeaton@wsu.edu, E-mail: m.duez@wsu.edu [Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States)

2013-10-10

321

Black Hole-Neutron Star Mergers with a Hot Nuclear Equation of State: Outflow and Neutrino-Cooled Disk for a Low-Mass, High-Spin Case  

E-print Network

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 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_{\\odot} neutron star, 5.6 M_{\\odot} black hole), high spin (black hole J/M^2=0.9) system with the K_0=220 MeV Lattimer-Swesty equation of state. We find that about 0.08 M_{\\odot} of nuclear matter is ejected from the system, while another 0.3 M_{\\odot} forms a hot, compact accretion disk. The primary effects of the escaping neutrinos are (i) to make the disk much denser and more compact, (ii) to cause the average electron fraction Y_e of the disk to rise to about 0.2 and then gradually decrease again, and (iii) to gradually cool the disk. The disk is initially hot (T~6 MeV) and luminous in neutrinos (L_{\

M. Brett Deaton; Matthew D. Duez; Francois Foucart; Evan O'Connor; Christian D. Ott; Lawrence E. Kidder; Curran D. Muhlberger; Mark A. Scheel; Bela Szilagyi

2013-04-11

322

Taurine detected using high-resolution magic angle spinning 1H nuclear magnetic resonance: A potential indicator of early myocardial infarction  

PubMed Central

Magnetic resonance spectroscopy (MRS) is a unique non-invasive method for detecting cardiac metabolic changes. However, MRS in cardiac diagnosis is limited due to insensitivity and low efficiency. Taurine (Tau) is the most abundant free amino acid in the myocardium. We hypothesized that Tau levels may indicate myocardial ischemia and early infarction. Sprague-Dawley rats were divided into seven groups according to different time points during the course of myocardial ischemia, which was induced by left anterior descending coronary artery ligation. Infarcted myocardial tissue was obtained for high-resolution magic angle spinning 1H nuclear magnetic resonance (NMR) analysis. Results were validated via high-performance liquid chromatography. The Tau levels in the ischemic myocardial tissue were reduced significantly within 5 min compared with those in the control group (relative ratio from 20.27±6.48 to 8.81±0.04, P<0.05) and were maintained for 6 h post-ischemia. Tau levels declined more markedly (56.5%) than creatine levels (48.5%) at 5 min after ligation. This suggests that Tau may have potential as an indicator in the early detection of myocardial ischemia by 1H MRS. PMID:23408155

YANG, YUNLONG; YANG, LIN; ZHANG, YUE; GU, XINGHUA; XU, DANLING; FANG, FANG; SUN, AIJUN; WANG, KEQIANG; YU, YIHUA; ZUO, JI; GE, JUNBO

2013-01-01

323

Long time evolution of a spin interacting with a spin bath in arbitrary magnetic field  

NASA Astrophysics Data System (ADS)

We introduce a completely different method to calculate the evolution of a spin interacting with a sufficient large spin bath, especially suitable for treating the central spin model in a quantum dot (QD). With only an approximation on the envelope of central spin, the symmetry can be exploited to reduce a huge Hilbert space which cannot be calculated with computers to many small ones which can be solved exactly. This method can be used to calculate spin-bath evolution for a spin bath containing many (say, 1000) spins, without a perturbative limit such as strong magnetic field condition, and works for long-time regime with sufficient accuracy. As the spin-bath evolution can be calculated for a wide range of time and magnetic field, an optimal dynamic of spin flip-flop can be found, and more sophisticated approaches to achieve extremely high polarization of nuclear spins in a QD could be developed.

Zhao, YuKang; Zhao, MeiSheng; Chen, ZengBing

2014-07-01

324

Nuclear physics  

Microsoft Academic Search

Low energy nuclear physics rather than high energy, or elementary ; particle physics is considered. Nuclear structure at a fairly basic level, spin ; and static electric and magnetic moments, approached from quantum mechanics ; rather than through the vector model of angular momentum, nuclear decay: both ; electromagnetic and beta-decay are treated using quantum mechanics, but without ; formal

Bowler

1973-01-01

325

High-spin properties from energy-energy correlation studies using the spin spectrometer  

SciTech Connect

The continuum ..gamma.. rays from /sup 130/Ce were studied using the spin spectrometer. One-dimensional and two-dimensional spectra were analyzed as a function of angle, spin and entry energy. Spin and temperature dependence of nuclear properties were observed.

Lee, I.Y.

1982-01-01

326

Spin Ice  

NASA Astrophysics Data System (ADS)

Pauling's model of hydrogen disorder in water ice represents the prototype of a frustrated system. Over the years it has spawned several analogous models, including Anderson's model antiferromagnet and the statistical "vertex" models. Spin Ice is a sixteen vertex model of "ferromagnetic frustration" that is approximated by real materials, most notably the rare earth pyrochlores Ho2Ti2O7, Dy2Ti2O7 and Ho2Sn2O7. These "spin ice materials" have the Pauling zero point entropy and in all respects represent almost ideal realisations of Pauling's model. They provide experimentalists with unprecedented access to a wide variety of novel magnetic states and phase transitions that are located in different regions of the field-temperature phase diagram. They afford theoreticians the opportunity to explore many new features of the magnetic interactions and statistical mechanics of frustrated systems. This chapter is a comprehensive review of the physics -- both experimental and theoretical -- of spin ice. It starts with a discussion of the historic problem of water ice and its relation to spin ice and other frustrated magnets. The properties of spin ice are then discussed in three sections that deal with the zero field spin ice state, the numerous field-induced states (including the recently identified "kagomé ice") and the magnetic dynamics. Some materials related to spin ice are briefly described and the chapter is concluded with a short summary of spin ice physics.

Bramwell, Steven T.; Gingras, Michel J. P.; Holdsworth, Peter C. W.

2013-03-01

327

Limits on Anomalous Spin-Spin Couplings between Neutrons  

SciTech Connect

We report experimental limits on new spin-dependent macroscopic forces between neutrons. We measured the nuclear Zeeman frequencies of a {sup 3}He/{sup 129}Xe maser while modulating the nuclear spin polarization of a nearby {sup 3}He 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{sub p}g{sub p}/(4{pi}({Dirac_h}/2{pi})c)] at the 3x10{sup -7} level for interaction ranges longer than about 40 cm. This limit is about 10{sup -5} the size of the magnetic dipole-dipole interaction between neutrons.

Glenday, Alexander G.; Walsworth, Ronald L. [Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138 (United States); Department of Physics, Harvard University, Cambridge, Massachusetts 02138 (United States); Cramer, Claire E.; Phillips, David F. [Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138 (United States)

2008-12-31

328

Initialization and readout of spin chains for quantum information transport  

E-print Network

Linear chains of spins acting as quantum wires are a promising approach for achieving scalable quantum information processors. Nuclear spins in apatite crystals provide an ideal test bed for the experimental study of quantum ...

Kaur, Gurneet

329

Blend compatibility study by solid-state 13C nuclear magnetic resonance  

Microsoft Academic Search

The application of proton spin–lattice relaxation time in the rotating frame and carbon-13 cross-polarization\\/magic-angle spinning to investigate the compatibility of a polymeric blend formed by high-density polyethylene (HDPE) and a synthetic petroleum resin of low molecular weight showed that this system presents a range of compatibility varying up to 40% (w\\/w) of the petroleum resin. The blends showed a shift

Maria Inês B. Tavares; L. C. Mendes

2000-01-01

330

Spins Package  

NSDL National Science Digital Library

The Spins package is a self-contained file for the teaching of measurement and time evolution of spin-1/2 systems in quantum mechanics. The file contains ready-to-run OSP programs and a set of curricular materials. The material focuses on single and multiple measurements of different ensembles of identically prepared spin-1/2 particles. The Spins package is an Open Source Physics curricular package written for the teaching of quantum mechanics. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the osp_spins.jar file will run the package if Java is installed. The original program, Spins, was written for the Macintosh by Daniel Schroeder and Thomas Moore and was then ported to Java by David McIntyre. We have made extensive modifications to the Java version of the SPINS program. Other quantum mechanics packages are also available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Quantum Mechanics.

Belloni, Mario; Christian, Wolfgang

2008-06-03

331

Nuclear  

NSDL National Science Digital Library

What part does nuclear energy play in satisfying energy demands? This informational piece, part of a series about the future of energy, introduces students to the uranium atom as an energy source. Here students read about the history of nuclear energy, how energy is derived from uranium, and benefits of nuclear energy. Information is also provided about limitations, particularly disposal problems and radioactivity, and geographical considerations of nuclear power in the United States. Thought-provoking questions afford students chances to reflect on what they've read about the uses of nuclear power. Articles and information on new nuclear plant design and nuclear accidents are available from a sidebar. Five energy-related PBS NewsHour links are provided. A web link to the U.S. Nuclear Regulatory Commission is included. Copyright 2005 Eisenhower National Clearinghouse

Project, Iowa P.

2004-01-01

332

Analysis of metabolic characteristics in a rat model of chronic pancreatitis using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy  

PubMed Central

Pathological and metabolic alterations co-exist and co-develop in the progression of chronic pancreatitis (CP). The aim of the present study was to investigate the metabolic characteristics and disease severity of a rat model of CP in order to determine associations in the observed pathology and the metabolites of CP using high-resolution magic-angle spinning nuclear magnetic resonance spectroscopy (HR-MAS NMR). Wistar rats (n=36) were randomly assigned into 6 groups (n=6 per group). CP was established by administering dibutyltin dichloride solution into the tail vein. After 0, 7, 14, 21, 28 and 35 days, the pancreatic tissues were collected for pathological scoring or for HR-MAS NMR. Correlation analyses between the major pathological scores and the integral areas of the major metabolites were determined. The most representative metabolites, aspartate, betaine and fatty acids, were identified as possessing the greatest discriminatory significance. The Spearman’s rank correlation coefficients between the pathology and metabolites of the pancreatic tissues were as follows: Betaine and fibrosis, 0.454 (P=0.044); betaine and inflammatory cell infiltration, 0.716 (P=0.0001); aspartate and fibrosis, ?0.768 (P=0.0001); aspartate and inflammatory cell infiltration, ?0.394 (P=0.085); fatty acid and fibrosis, ?0.764 (P=0.0001); and fatty acid and inflammatory cell infiltration, ?0.619 (P=0.004). The metabolite betaine positively correlated with fibrosis and inflammatory cell infiltration in CP. In addition, aspartate negatively correlated with fibrosis, but exhibited no significant correlation with inflammatory cell infiltration. Furthermore, the presence of fatty acids negatively correlated with fibrosis and inflammatory cell infiltration in CP. HR-MAS NMR may be used to analyze metabolic characteristics in a rat model of different degrees of chronic pancreatitis. PMID:25338744

TIAN, BING; MA, CHAO; WANG, JIAN; PAN, CHUN-SHU; YANG, GEN-JIN; LU, JIAN-PING

2015-01-01

333

Analysis of metabolic characteristics in a rat model of chronic pancreatitis using high?resolution magic?angle spinning nuclear magnetic resonance spectroscopy.  

PubMed

Pathological and metabolic alterations co?exist and co?develop in the progression of chronic pancreatitis (CP). The aim of the present study was to investigate the metabolic characteristics and disease severity of a rat model of CP in order to determine associations in the observed pathology and the metabolites of CP using high?resolution magic?angle spinning nuclear magnetic resonance spectroscopy (HR?MAS NMR). Wistar rats (n=36) were randomly assigned into 6 groups (n=6 per group). CP was established by administering dibutyltin dichloride solution into the tail vein. After 0, 7, 14, 21, 28 and 35 days, the pancreatic tissues were collected for pathological scoring or for HR?MAS NMR. Correlation analyses between the major pathological scores and the integral areas of the major metabolites were determined. The most representative metabolites, aspartate, betaine and fatty acids, were identified as possessing the greatest discriminatory significance. The Spearman's rank correlation coefficients between the pathology and metabolites of the pancreatic tissues were as follows: Betaine and fibrosis, 0.454 (P=0.044); betaine and inflammatory cell infiltration, 0.716 (P=0.0001); aspartate and fibrosis, ?0.768 (P=0.0001); aspartate and inflammatory cell infiltration, ?0.394 (P=0.085); fatty acid and fibrosis, ?0.764 (P=0.0001); and fatty acid and inflammatory cell infiltration, ?0.619 (P=0.004). The metabolite betaine positively correlated with fibrosis and inflammatory cell infiltration in CP. In addition, aspartate negatively correlated with fibrosis, but exhibited no significant correlation with inflammatory cell infiltration. Furthermore, the presence of fatty acids negatively correlated with fibrosis and inflammatory cell infiltration in CP. HR?MAS NMR may be used to analyze metabolic characteristics in a rat model of different degrees of chronic pancreatitis. PMID:25338744

Tian, Bing; Ma, Chao; Wang, Jian; Pan, Chun-Shu; Yang, Gen-Jin; Lu, Jian-Ping

2015-01-01

334

Proton and deuterium nuclear spin relaxation study of the SmA and SmC* phases of BP8Cl-d17 : a self-consistent analysis.  

PubMed

A self-consistent analysis of proton and deuterium nuclear spin relaxation times in the smectic phases of a partially deuterated smectogen is presented here. Proton spin-lattice relaxation times T1Z were measured as a function of Larmor frequency over a range of 1?kHz to 300?MHz at selected temperatures. Deuterium spin relaxation times T1Z and T1Q were measured as a function of temperature at two different magnetic fields in the smectic A phase. The deuterium data provide dynamic parameters such as rotational diffusion constants and internal jump rates as well as the nematic order parameter S. The proton data are analyzed using a number of relaxation mechanisms, one of which is the molecular reorientation. It is found helpful in these latter analyses to use the nematic order parameter and to fix the contribution from molecular reorientations determined by the deuterium spin relaxation. The fits to the proton T1 frequency and temperature dispersions by the remaining relaxation mechanisms such as layer undulations and translational self-diffusion will be discussed for the smectic A and chiral smectic C phases. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25132369

Ferraz, A; Zhang, J; Sebastião, P J; Ribeiro, A C; Dong, Ronald Y

2014-10-01

335

Transfer of spin angular momentum from Cs vapor to nearby Cs salts through laser-induced spin currents  

SciTech Connect

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.

Ishikawa, K.; Patton, B.; Olsen, B. A.; Jau, Y.-Y.; Happer, W. [Graduate School of Material Science, University of Hyogo, Ako-gun, Hyogo 678-1297 (Japan); Joseph Henry Laboratory, Department of Physics, Princeton University, Princeton, New Jersey 08544 (United States)

2011-06-15

336

Coherence of Donor Electron Spins in Isotopically Enriched Silicon  

NASA Astrophysics Data System (ADS)

Silicon is promising for spin-based quantum computing because nuclear spins, a source of magnetic noise, may be nearly eliminated through enrichment. However, any Si device is expected to contain some phosphorus donor impurities. These donors generate magnetic noise through spin dynamics, induced by dipolar interactions, that conserve Zeeman and hyperfine energies. Ironically, increasing the number of nuclear spins will suppress this decoherence mechanism by effecting more hyperfine energy variation (i.e., Overhauser shifts). We study spin coherence decay as a function of donor concentration, ^29Si concentration, and temperature using cluster expansion techniques specifically adapted to the problem of a sparse electron spin bath.

Witzel, Wayne; Muller, Richard; Carroll, Malcolm; Morello, Andrea; Cywinski, Lukasz; Das Sarma, Sankar

2010-03-01

337

Measuring central-spin interaction with a spin bath by pulsed ENDOR: Towards suppression of spin diffusion decoherence  

NASA Astrophysics Data System (ADS)

We present pulsed electron-nuclear double resonance (ENDOR) experiments which enable us to characterize the coupling between bismuth donor spin qubits in Si and the surrounding spin bath of 29Si impurities which provides the dominant decoherence mechanism (nuclear spin diffusion) at low temperatures (<16 K). Decoupling from the spin bath is predicted and cluster correlation expansion simulations show near-complete suppression of spin diffusion, at optimal working points. The suppression takes the form of sharply peaked divergences of the spin diffusion coherence time, in contrast with previously identified broader regions of insensitivity to classical fluctuations. ENDOR data suggest that anisotropic contributions are comparatively weak, so the form of the divergences is largely independent of crystal orientation.

Balian, S. J.; Kunze, M. B. A.; Mohammady, M. H.; Morley, G. W.; Witzel, W. M.; Kay, C. W. M.; Monteiro, T. S.

2012-09-01

338

Microfabricated Spin Polarized Atomic Magnetometers  

NASA Astrophysics Data System (ADS)

Spin polarized atomic magnetometers involve the preparation of atomic spins and their detection for monitoring magnetic fields. Due to the fact that magnetic fields are ubiquitous in our world, spin polarized atomic magnetometers are used in a wide range of applications from the detection of magnetic fields generated by the human heart and brain to the detection of nuclear magnetic resonance. In this thesis we developed microfabricated spin polarized atomic magnetometers. These sensors are based on optical pumping and spin-exchange collisions between alkali atoms and noble gases contained in microfabricated millimeter-scale vapor cells. In the first part of the thesis, we improved different features of current microfabricated optical magnetometers. Specifically, we improved the bandwidth of these devices, without degrading their magnetic field sensitivity, by broadening their magnetic resonance through spin-exchange collisions between alkali atoms. We also implemented all-optical excitation techniques to avoid problems, such as the magnetic perturbation of the environment, induced by the radio-frequency fields used in some of these sensors. In the second part of the thesis we demonstrated a microfluidic chip for the optical production and detection of hyperpolarized Xe gas through spin-exchange collisions with optically pumped Rb atoms. These devices are critical for the widespread use of spin polarized atomic magnetometers in applications requiring simple, compact, low-cost, and portable instrumentation.

Jimenez Martinez, Ricardo

339

Study of the carbon-13 and deuterium kinetic isotope effects in the Cl and OH reactions of CH4 and CH3Cl.  

PubMed

Relative rate experiments have been carried out for three isotopologues of chloromethane and their reactions with Cl atoms and OH radicals. The OH and Cl reaction rates of CH2DCl and CHD2Cl were measured by long-path FTIR spectroscopy relative to CH3Cl at 298+/-2 K and 1013+/-10 hPa in purified air. The FTIR spectra were fitted using a nonlinear least squares spectral fitting method including measured high-resolution infrared spectra as references. The relative reaction rates defined by alpha=klight/kheavy were determined to be kOH+CH3Cl/kOH+CH2DCl=1.41+/-0.05, kOH+CH3Cl/kOH+CHD2Cl=2.03+/-0.05, kCl+CH3Cl/kCl+CH2DCl=1.42+/-0.04, and kCl+CH3Cl/kCl+CHD2Cl=2.27+/-0.04. The carbon-13 and deuterium kinetic isotope effects in the OH and Cl reactions of CH3Cl were investigated further using variational transition state theory, and the results were compared to similar calculations performed for the CH4+OH/Cl reaction systems. The calculations show that the order of magnitude difference for the carbon-13 kinetic isotope effect in the OH reaction of CH3Cl compared to CH4 reported by Gola et al. (Atmos. Chem. Phys. 2005, 5, 2395) can be explained by the lower barrier to internal rotation of the OH radical in the transition state of the CH4+OH reaction than in the CH3Cl+OH reaction. The deuterium kinetic isotope effects can be explained in terms of combined variational effects and tunneling. PMID:16392849

Sellevåg, Stig R; Nyman, Gunnar; Nielsen, Claus J

2006-01-12

340

Hole spin precession in a (In,Ga)As quantum dot ensemble: From resonant spin amplification to spin mode locking  

NASA Astrophysics Data System (ADS)

Coherent collective phenomena of hole spins confined in an ensemble of (In,Ga)As quantum dots are studied by monitoring their Larmor precession about a magnetic field. Variation of the field strength drives the hole spins from a regime of resonant spin amplification, in which their precession frequency is a unique multiple of the laser repetition rate, to spin mode locking, in which several precession modes are commensurable with the laser repetition rate. In this regime the spin coherence time of individual holes is determined to be 0.7 ?s. In contrast, electron spins in the quantum dots are always trapped in the mode-locking regime due to the strong hyperfine interaction with nuclear spins.

Varwig, S.; Schwan, A.; Barmscheid, D.; Müller, C.; Greilich, A.; Yugova, I. A.; Yakovlev, D. R.; Reuter, D.; Wieck, A. D.; Bayer, M.

2012-08-01

341

Carbon-13 NMR studies of salt shock-induced carbohydrate turnover in the marine cyanobacterium Agmenellum quadruplicatum  

NASA Technical Reports Server (NTRS)

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.

Tel-Or, E.; Spath, S.; Packer, L.; Mehlhorn, R. J.

1986-01-01

342

Polyoxometalates as spin qubits  

NASA Astrophysics Data System (ADS)

Polyoxometalates (POMs) are discrete fragments of metal oxides, clusters of regular MOn polyhedra. POMs show a remarkable flexibility in composition, structure and charge state, and thus can be designed according to specific electric and magnetic needs. The two localized spins with S = 1/2 on the V atoms in [PMo12O40(VO)2]^q- can be coupled through the delocalized electrons of the central core. This system was recently used for a theoretical scheme involving two-qubit gates and readout: the electrical manipulation of the molecular redox potential changes the charge of the core and thus the effective magnetic exchange between the qubits. Polyoxometalates can encapsulate magnetic ions, protecting them by a diamagnetic shell of controlled geometry. A great potential of POMs as spin qubits is that they can be constructed using only even elements, such as O, W, Mo and/or Si. Thus, there is a high abundance of polyoxometalate molecules without any nuclear spin, which could result in unusually low decoherence rates. There is currently an effort involving highly anisotropic, high magnetic moment, lanthanide@polyoxometalate molecules acting as spin qubits.

Gaita-Ariño, A.; Aldamen, M.; Clemente-Juan, J.-M.; Coronado, E.; Lehmann, J.; Loss, D.; Stamp, P.

2008-03-01

343

Spin noise spectroscopy in semiconductors: from a billion down to single spins  

NASA Astrophysics Data System (ADS)

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.

Hübner, J.; Dahbashi, R.; Berski, F.; Wiegand, J.; Kuhn, H.; Lonnemann, J.; Oestreich, M.

2014-08-01

344

Examination of the exchange interaction through micellar size. 3. Stimulated nuclear polarization and time resolved electron spin resonance spectra from the photolysis of methyl deoxybenzoin in alkyl sulfate micelles of different size  

SciTech Connect

Stimulated nuclear polarization (SNP) and time resolved electron spin resonance (TR ESR) spectra were recorded during the laser flash photolysis of [sup 13]C carbonyl labeled [alpha]-methyldeoxybenzoin solubilized in a series of alkyl sulfate micelles of different sizes. While the SNP spectra show a decrease in the splitting of the two hyperfine lines with decreasing micelle size, this decrease in hyperfine splitting is not seen in the experimental TR ESR spectra The qualitatively different variations between the SNP and TR ESR spectra, as a function of micelle size were interpreted in terms of the stochastic Liouville equation as applied to the model of the microreactor. 28 refs., 6 figs., 2 tabs.

Tarasov, V.F. (Russian Academy of Sciences, Moscow (Russian Federation)); Bagranskaya, E.G.; Avdievich, N.I.; Lukzen, N.N.; Sagdeev, R.Z. (International Tomography Center, Novosibirsk (Russian Federation)); Shkrob, I.A. (Argonne National Lab., IL (United States)); Ghatlia, N.D.; Turro, N.J. (Columbia Univ., New York, NY (United States))

1995-01-11

345

THz Dynamic Nuclear Polarization NMR  

E-print Network

Dynamic nuclear polarization (DNP) increases the sensitivity of nuclear magnetic resonance (NMR) spectroscopy by using high frequency microwaves to transfer the polarization of the electrons to the nuclear spins. The ...

Nanni, Emilio Alessandro

346

Spin and spin-isospin instabilities and Landau parameters of Skyrme interactions with tensor correlations  

SciTech Connect

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.

Cao Ligang [Institute of Modern Physics, Chinese Academy of Science, Lanzhou 730000 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Accelerator of Lanzhou, Lanzhou 730000 (China); Dipartimento di Fisica, Universita degli Studi di Milano, via Celoria 16, Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, Milano (Italy); Colo, Gianluca [Dipartimento di Fisica, Universita degli Studi di Milano, via Celoria 16, Milano (Italy); Istituto Nazionale di Fisica Nucleare (INFN), Sez. di Milano, via Celoria 16, Milano (Italy); Sagawa, Hiroyuki [Center for Mathematics and Physics, University of Aizu, Aizu-Wakamatsu, Fukushima 965-8560 (Japan)

2010-04-15

347

Microtesla MRI with dynamic nuclear polarization  

PubMed Central

Magnetic resonance imaging at microtesla fields is a promising imaging method that combines the pre-polarization technique and broadband signal reception by superconducting quantum interference device (SQUID) sensors to enable in vivo MRI at microtesla-range magnetic fields similar in strength to the Earth magnetic field. Despite significant advances in recent years, the potential of microtesla MRI for biomedical imaging is limited by its insufficient signal-to-noise ratio due to a relatively low sample polarization. Dynamic nuclear polarization (DNP) is a widely used approach that allows polarization enhancement by two-four orders of magnitude without an increase in the polarizing field strength. In this work, the first implementation of microtesla MRI with Overhauser DNP and SQUID signal detection is described. The first measurements of carbon-13 NMR spectra at microtesla fields are also reported. The experiments were performed at the measurement field of 96 microtesla, corresponding to Larmor frequency of 4 kHz for protons and 1 kHz for carbon-13. The Overhauser DNP was carried out at 3.5 –5.7 mT field using rf irradiation at 120 MHz. Objects for imaging included water phantoms and a cactus plant. Aqueous solutions of metabolically relevant sodium bicarbonate, pyruvate, alanine, and lactate, labeled with carbon-13, were used for NMR studies. All the samples were doped with TEMPO free radicals. The Overhauser DNP enabled nuclear polarization enhancement by factor as high as ?95 for protons and as high as ?200 for carbon-13, corresponding to thermal polarizations at 0.33 T and 1.1 T fields, respectively. These results demonstrate that SQUID-based microtesla MRI can be naturally combined with Overhauser DNP in one system, and that its signal-to-noise performance is greatly improved in this case. They also suggest that microtesla MRI can become an efficient tool for in vivo imaging of hyperpolarized carbon-13, produced by the low-temperature dissolution DNP. PMID:20843715

Zotev, Vadim S.; Owens, Tuba; Matlashov, Andrei N.; Savukov, Igor M.; Gomez, John J.; Espy, Michelle A.

2010-01-01

348

The characterization of human compact bone structure changes by low-field nuclear magnetic resonance  

Microsoft Academic Search

A technique of low-field pulsed proton nuclear magnetic resonance (NMR) spin relaxation is described for characterizing the porosity and (effective) pore size distribution in vitro in human compact bone. The technique involves spin spin relaxation measurement and inversion spin spin relaxation spectral analysis methods. The spin spin relaxation decay curve is converted into a T2 distribution spectrum by a sum

Qingwen Ni; J. Derwin King; Xiaodu Wang

2004-01-01

349

Architectures for a Spin Quantum Computer Based on Endohedral Fullerenes  

E-print Network

Architectures for a Spin Quantum Computer Based on Endohedral Fullerenes W. Harneit1 ) (a), C computer using endohedral fullerenes. The fullerene molecule is a static, room-temperature trap for atoms with slowly relaxing electron and nuclear spins. The fullerene "containers" can be used to arrange the spins

Suter, Dieter

350

Experimental classification of multi-spin coherence under the full rotation group  

Microsoft Academic Search

The density operator of a coupled nuclear spin system often includes multi-spin coherences representing correlations between different spins. The generation and evolution of these coherences is governed by the dipole-dipole interactions between the spins and thus contains information about nuclear structure. Different multi-spin coherences may be distinguished by their behaviour under rotations. The maximum information extractable is determined by the

D. Suter; J. G. Pearson

1988-01-01

351

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  

NASA Astrophysics Data System (ADS)

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.

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

2013-04-01

352

Electrical control of quantum dot spin qubits  

NASA Astrophysics Data System (ADS)

This thesis presents experiments exploring the interactions of electron spins with electric fields in devices of up to four quantum dots. These experiments are particularly motivated by the prospect of using electric fields to control spin qubits. A novel hyperfine effect on a single spin in a quantum dot is presented in Chapter 2. Fluctuations of the nuclear polarization allow single-spin resonance to be driven by an oscillating electric field. Spin resonance spectroscopy revealed a nuclear polarization built up inside the quantum dot device by driving the resonance. The evolution of two coupled spins is controlled by the combination of hyperfine interaction, which tends to cause spin dephasing, and exchange, which tends to prevent it. In Chapter 3, dephasing is studied in a device with tunable exchange, probing the crossover between exchange-dominated and hyperfine-dominated regimes. In agreement with theoretical predictions, oscillations of the spin conversion probability and saturation of dephasing are observed. Chapter 4 deals with a three-dot device, suggested as a potential qubit controlled entirely by exchange. Preparation and readout of the qubit state are demonstrated, together with one out of two coherent exchange operations needed for arbitrary manipulations. A new readout technique allowing rapid device measurement is described. In Chapter 5, an attempt to make a two-qubit gate using a four-dot device is presented. Although spin qubit operation has not yet been possible, the electrostatic interaction between pairs of dots was measured to be sufficient in principle for coherent qubit coupling.

Laird, Edward Alexander

353

Spin dephasing in disordered semiconductors and metals  

NASA Astrophysics Data System (ADS)

The spin dephasing time T2 of electrons in a very dirty metal is calculated. The dephasing is due to weak scattering processes which do not conserve the total electron spin. Two scattering processes which are of particular importance in the impurity band of many-valley semiconductors are considered: nuclear spin flip and intervalley spin orbit. The diffusive nature of the electron motion enhances the spin dephasing rate over the usual rate present in clean metals. Electron-electron interactions are shown to have strong effects upon this diffusive process and lead to an enhanced dephasing rate. To lowest order in the interactions this enhancement is proportional to the enhancement of the spin susceptibility. Quantitative comparison is made with experiments in phosphorus-doped silicon.

Sachdev, Subir

1987-05-01

354

Spin-Liquid Condensate of Spinful Bosons  

NASA Astrophysics Data System (ADS)

We introduce the concept of a bosonic spin liquid condensate (SLC), where spinful bosons in a lattice form a zero-temperature spin disordered charge condensate that preserves the spin rotation symmetry, but breaks the U(1) symmetry due to a spinless order parameter with charge one. It has an energy gap to all the spin excitations. We show that such SLC states can be realized in a system of spin S ?2 bosons. In particular, we analyze the SLC phase diagram in the spin 2 case using a mean-field variational wave function method. We show there is a direct analogy between the SLC and the resonating-valence-bond state.

Lian, Biao; Zhang, Shoucheng

2014-08-01

355

Spin Correlations in Ho2Ti2O7: A Dipolar Spin Ice System  

NASA Astrophysics Data System (ADS)

The pyrochlore material Ho2Ti2O7 has been suggested to show ``spin ice'' behavior. We present neutron scattering and specific heat results that establish unambiguously that Ho2Ti2O7 exhibits spin ice correlations at low temperature. Diffuse magnetic neutron scattering is quite well described by a nearest neighbor spin ice model and very accurately described by a dipolar spin ice model. The heat capacity is well accounted for by the sum of a dipolar spin ice contribution and an expected nuclear spin contribution, known to exist in other Ho3+ salts. These results settle the question of the nature of the low temperature spin correlations in Ho2Ti2O7 for which contradictory claims have been made.

Bramwell, S. T.; Harris, M. J.; den Hertog, B. C.; Gingras, M. J.; Gardner, J. S.; McMorrow, D. F.; Wildes, A. R.; Cornelius, A. L.; Champion, J. D.; Melko, R. G.; Fennell, T.

2001-07-01

356

Spin correlations in Ho2Ti2O7: a dipolar spin ice system.  

PubMed

The pyrochlore material Ho2Ti2O7 has been suggested to show "spin ice" behavior. We present neutron scattering and specific heat results that establish unambiguously that Ho2Ti2O7 exhibits spin ice correlations at low temperature. Diffuse magnetic neutron scattering is quite well described by a nearest neighbor spin ice model and very accurately described by a dipolar spin ice model. The heat capacity is well accounted for by the sum of a dipolar spin ice contribution and an expected nuclear spin contribution, known to exist in other Ho3+ salts. These results settle the question of the nature of the low temperature spin correlations in Ho2Ti2O7 for which contradictory claims have been made. PMID:11461643

Bramwell, S T; Harris, M J; den Hertog, B C; Gingras, M J; Gardner, J S; McMorrow, D F; Wildes, A R; Cornelius, A L; Champion, J D; Melko, R G; Fennell, T

2001-07-23

357

Relaxation equations for the magnetic moment of a system of coupled spins  

Microsoft Academic Search

Redfield's equation [4] for the spin-density matrix is used to derive the macroscopic relaxation equations for the magnetic moment of a system of three nuclear spins coupled by dipole-dipole interaction. The relaxation is due to the Brownian rotation of the molecule in which the spin nuclei are randomly placed. The relaxation problem is solved for a system of spins at

N. N. Korst; O. A. Nikich-Krilichevskii

1967-01-01

358

PREFACE: SPIN2010 - Preface for Conference Proceedings  

NASA Astrophysics Data System (ADS)

SPIN2010, the 19th International Spin Physics Symposium, took place between 27 September and 2 October, 2010 on the campus of Forschungszentrum Jülich GmbH (FZJ) in Jülich, Germany. The scientific program of this Symposium included many topics related to spin phenomena in particle and nuclear physics as well as those in related fields. The International Spin Physics Symposium series has combined the High Energy Spin Symposia and the Nuclear Polarization Conferences since 2000. The most recent two Symposia were held in Virginia, USA (October 2008) and in Kyoto, Japan (October 2006). The meeting was opened by the chairman of the Board of Management of Jülich Forschungszentrum, Professor Achim Bachem, who cordially welcomed the participants from all over the world and gave a brief introduction to the Center and the research conducted there. The scientific program consisted of plenary sessions and parallel sessions and included the following topics: Fundamental symmetries and spin Spin structure of hadrons Spin physics beyond the Standard Model Spin in hadronic reactions Spin physics with photons and leptons Spin physics in nuclear reactions and nuclei Acceleration, storage, and polarimetry of polarized beams Polarized ion and lepton sources and targets Future facilities and experiments Medical and technological applications of spin physics The 6-day symposium had about 300 participants. In total 35 plenary talks (including 3 summaries of other spin physics meetings) and 163 contributed talks were given. The contents of many of these can be found in the present contributions, arranged according to the above topics and the time sequence. In addition, a public lecture on "Drall in der Quantenwelt", presented by H O Meyer (Bloomington) was received very well. Participants had the option to visit the Cooler synchrotron COSY at the Nuclear Physics Institute (IKP) and the 9.4 T MRT-PET hybrid scanner at the Institute of Neuroscience and Medicine (INM), two unique facilities at FZJ, and many made the most of the opportunity. We gratefully acknowledge the financial support from Brookhaven National Laboratory (BNL, USA), Forschungszentrum Jülich (FZJ), the International Union of Pure And Applied Physics (IUPAP), Thomas Jefferson Laboratory (JLab, USA), Helmholtz Institute Mainz (HIM, Germany) and the Virtual Institute on Spin and Strong QCD (VI-QCD) of the Helmholtz Association (HGF). We would also like to thank the local people from IKP and other institutions of FZJ for their contributions and help - without them we would not have been able to organize this great meeting. The current proceedings comprise written contributions of many of the presentations during SPIN2010; however, due to the recent incident in Japan, a number of our colleagues from there were unfortunately not able to deliver their write-ups in due time. This volume was edited by Ralf Gebel, Christoph Hanhart, Andro Kacharava, Andreas Lehrach, Bernd Lorentz, Nikolai N Nikolaev, Andreas Nogga, Frank Rathmann, and Hans Ströher. The next symposium - SPIN2012 - will be held at the Joint Institute for Nuclear Research (JINR) in Dubna (Russia) in 2012. We are looking forward to meeting you there. Important conference-related links: SPIN2010 Web-site: https://www.congressa.de/SPIN2010/ Article in CERN Courier: http://cerncourier.com/cws/article/cern/45451 Spin Physics Committee: http://www.spin-community.org Jülich, April 2011 - Hans Ströher, Frank Rathmann (Chairs SPIN2010) Conference photograph

Ströher, Hans; Rathmann, Frank

2011-03-01

359

Spin injection efficiency in spin electronic devices  

NASA Astrophysics Data System (ADS)

We examine the comparative importance of spin injection efficiency in different types of spin electronic devices. We analyse the devices using a "pseudo-density of states" treatment of spin currents coupled to the principle of spin balance. This approach affords a generality that readily encompasses both metal and semiconductor direct spin injection systems. This implies that the various spin electronic devices have differing criteria for assessing the quality of their performance and that in turn these criteria determine the importance of implementing high-efficiency spin injection. We examine the factors which determine the obtainable spin injection performance in each case. We conclude that for CPP trilayer devices with semiconductor interlayers, obtaining efficient spin injection should not be a problem so long as the semiconductor layer thickness is small compared with its own spin diffusion length. Direct-injected and tunnel-injected spin LEDs are predicted to have similar spin efficiencies. However, direct-injected SPICE-type spin transistors have superior spin performance to their tunnel-injected counterparts.

Gregg, J. F.; Borges, R. P.; Jouguelet, E.; Dennis, C. L.; Petej, I.; Thompson, S. M.; Ounadjela, K.

2003-10-01

360

Dynamical Self-Quenching of Spin Pumping into Double Quantum Dots  

NASA Astrophysics Data System (ADS)

Nuclear spin polarization can be pumped into spin-blockaded quantum dots by multiple Landau-Zener passages through singlet-triplet anticrossings. By numerical simulations of realistic systems with 107 nuclear spins during 105 sweeps, we uncover a mechanism of dynamical self-quenching which results in a fast saturation of the nuclear polarization under stationary pumping. This is caused by screening the random field of the nuclear spins. For moderate spin-orbit coupling, self-quenching persists but its patterns are modified. Our finding explains low polarization levels achieved experimentally and calls for developing new protocols that break the self-quenching limitations.

Brataas, Arne; Rashba, Emmanuel I.

2012-12-01

361

Single-atom spin qubits in silicon  

NASA Astrophysics Data System (ADS)

Spin qubits in silicon are excellent candidates for scalable quantum information processing (QIP) due to their long coherence times and the enormous investment in silicon MOS technology. Here I discuss qubits based upon single phosphorus (P) dopant atoms in Si [1]. Projective readout of such qubits had proved challenging until single-shot measurement of a single donor electron spin was demonstrated [2] using a silicon single electron transistor (Si-SET) and the process of spin-to-charge conversion. The measurement gave readout fidelities 90% and spin lifetimes T1e 6 s [2], opening the path to demonstration of electron and nuclear spin qubits in silicon. Integrating an on-chip microwave transmission line enabled single-electron spin resonance (ESR) of the P donor electron. We used this to demonstrate Rabi oscillations of the electron spin qubit, while a Hahn echo sequence revealed electron spin coherence times T2e 0.2 ms [3]. This time is expected to become much longer in isotopically enriched ^28Si devices. We also achieved single-shot readout of the ^31P nuclear spin (with fidelity 99.6%) by monitoring the two hyperfine-split ESR lines of the P donor system. By applying (local) NMR pulses we demonstrated coherent control of the nuclear spin qubit, giving a coherence time T2n 60 ms. [4pt] [1] B.E. Kane, Nature 393, 133 (1998). [2] A. Morello et al., Nature 467, 687 (2010). [3] J.J. Pla et al., Nature 489, 541 (2012).

Dzurak, Andrew

2013-03-01

362

Quantum Cavity for Spin due to Spin-Orbit Interaction at a Metal Boundary  

NASA Astrophysics Data System (ADS)

A quantum cavity for spin is created using a tungsten crystal as substrate of high nuclear charge and breaking the structural inversion symmetry through deposition of a gold quantum film. Spin- and angle-resolved photoelectron spectroscopy shows directly that quantum-well states and the “matrioshka” or Russian nested doll Fermi surface of the gold film are spin polarized and spin-orbit split up to a thickness of at least nine atomic layers. Ferromagnetic materials or external magnetic fields are not required, and the quantum film does not need to possess a high atomic number as analogous results with silver show.

Varykhalov, A.; Sánchez-Barriga, J.; Shikin, A. M.; Gudat, W.; Eberhardt, W.; Rader, O.

2008-12-01

363

Nuclear Magnetic Resonance Spectroscopy. 13C Fourier Transform Spectra of ?8- and ?9-Tetrahydrocannabinol  

PubMed Central

Carbon-13 nuclear magnetic resonance spectra have been taken of ?8- and ?9-tetrahydrocannabinol. The absorptions have been assigned to specific carbons with the aid of off-resonance and selective proton-decoupling experiments, as well as by chemical-shift comparison with model compounds. PMID:4515603

Hawkins, Bruce L.; Roberts, John D.

1973-01-01

364

Gordon Conference on Nuclear Research  

SciTech Connect

Session topics were: quarks and nuclear physics; anomalons and anti-protons; the independent particle structure of nuclei; relativistic descriptions of nuclear structure and scattering; nuclear structure at high excitation; advances in nuclear astrophysics; properties of nuclear material; the earliest moments of the universe; and pions and spin excitations in nuclei.

Austin, S.M.

1983-09-01

365

Triple-quantum two-dimentional ²⁷Al magic-angle spinning nuclear magnetic resonance spectroscopic study of aluminosilicate and aluminate crystals and glasses  

Microsoft Academic Search

A new two-dimensional magic-angle spinning NMR experiment using multiple-quantum coherence of half-integer quadrupolar nuclei was used to study ²⁷Al sites in crystalline samples of leucite (KAlSiâOâ), anorthite (CaAlâSiâOâ), and kyanite (AlâSiOâ), as well as CaAlâSiâOâ glass and a magnesium aluminoborate glass. In the crystals, multiple sites are partially resolved and new results for isotropic chemical shifts and quadrupolar parameters are

J. H. Baltisberger; Z. Xu; J. F. Stebbins; S. H. Wang; A. Pines

1996-01-01

366

Electronic spin state of lower mantle perovskite at conditions of the deep Earth's interior from in situ high P,T nuclear resonance measurements  

NASA Astrophysics Data System (ADS)

Iron-, aluminum-containing magnesium silicate perovskite (FeAlPv) is believed to be the main component of the Earth's lower mantle. The electronic spin state of iron in different valence states in FeAlPv may affect thermal and electrical conductivities, thermodynamic and other properties of the Earth's interior. Numerous high pressure studies of iron in FeAlPv have been performed and many of the studies gave conflicting results. Mössbauer spectroscopy provides information on the abundance of individual iron species (valence and spin state as well as site occupation); however up until now high temperature studies were limited to only 800 K using a resistively heated diamond anvil cell. The recently developed Synchrotron Mössbauer Source at the European Synchrotron Radiation Facility coupled with a portable laser-heating system for diamond anvil cells allows the collection of in situ energy domain Mössbauer spectroscopic data at conditions of the Earth's lower mantle. We will present the first high-pressure high-temperature studies on the iron electronic configuration in FeAlPv measured using Mössbauer spectroscopy, complemented by investigations at high pressure and ambient temperature that provide high resolution data for the analysis of individual site and valence state contributions. We will present the methodology of spectra interpretation and discuss the implications of the results to the properties of the Earth's interior.

Kupenko, I.; McCammon, C. A.; Sinmyo, R.; Cerantola, V.; Potapkin, V.; Chumakov, A.; Kantor, A.; Rüffer, R.; Dubrovinsky, L. S.

2013-12-01

367

The JLab Frozen Spin Target  

SciTech Connect

A polarized, frozen spin target has been designed and constructed at Jefferson Lab for use inside the CEBAF Large Acceptance Spectrometer. Protons in TEMPO-doped butanol are polarized via dynamic nuclear polarization (DNP) to approximately 90% using microwaves and an external, 5 T solenoid magnet. The target sample is then cooled to approximately 30 mK while an internal 0.56 T superconducting magnet is used to maintain the polarization. Relaxation times in excess of 3500 hours have been observed.

Keith, C. D. [Thomas Jefferson National Accelerator Facility, Newport News, VA 23606 (United States)

2009-08-04

368

A coherent beam splitter for electronic spin states.  

PubMed

Rapid coherent control of electron spin states is required for implementation of a spin-based quantum processor. We demonstrated coherent control of electronic spin states in a double quantum dot by sweeping an initially prepared spin-singlet state through a singlet-triplet anticrossing in the energy-level spectrum. The anticrossing serves as a beam splitter for the incoming spin-singlet state. When performed within the spin-dephasing time, consecutive crossings through the beam splitter result in coherent quantum oscillations between the singlet state and a triplet state. The all-electrical method for quantum control relies on electron-nuclear spin coupling and drives single-electron spin rotations on nanosecond time scales. PMID:20133567

Petta, J R; Lu, H; Gossard, A C

2010-02-01

369

New Experiments with Spinning Metallic Discs  

NASA Technical Reports Server (NTRS)

A number of recent advanced theories related to torsion properties of the space-time matrix predict the existence of an interaction between classically spinning objects. Indeed, some experimental data suggest that spinning magnetic bodies discernibly interact with Earth's natural fields. If there are interactions between rotating bodies then nuclear spins could be used for detection. Thus, assuming a spinning body induces a hypothetical torsion field, a sensor based on the giant magnetoresistance effect would detect local changes. Experimentally, spinning a brass wheel shielded from Earth's magnetic field showed no measurable change in signals; with no shielding a Faraday disc phenomenon was observed. Unexpected experimental measurements from the non-axial Faraday disc configuration were recorded and a theoretical model was derived to explain them.

Mazuruk, Konstantin; Grugel, Richard N.

2003-01-01

370

Single spin stochastic optical reconstruction microscopy  

E-print Network

We experimentally demonstrate precision addressing of single quantum emitters by combined optical microscopy and spin resonance techniques. To this end we utilize nitrogen-vacancy (NV) color centers in diamond confined within a few ten nanometers as individually resolvable quantum systems. By developing a stochastic optical reconstruction microscopy (STORM) technique for NV centers we are able to simultaneously perform sub diffraction-limit imaging and optically detected spin resonance (ODMR) measurements on NV spins. This allows the assignment of spin resonance spectra to individual NV center locations with nanometer scale resolution and thus further improves spatial discrimination. For example, we resolved formerly indistinguishable emitters by their spectra. Furthermore, ODMR spectra contain metrology information allowing for sub diffraction-limit sensing of, for instance, magnetic or electric fields with inherently parallel data acquisition. As an example, we have detected nuclear spins with nanometer sca...

Pfender, Matthias; Waldherr, Gerald; Wrachtrup, Jörg

2014-01-01

371

Neutrino nuclear response and photo nuclear reaction  

E-print Network

Photo nuclear reactions are shown to be used for studying neutrino/weak nuclear responses involved in astro-neutrino nuclear interactions and double beta decays. Charged current weak responses for ground and excited states are studied by using photo nuclear reactions through isobaric analog states of those states, while neutral current weak responses for excited states are studied by using photo nuclear reactions through the excited states. The weak interaction strengths are studied by measuring the cross sections of the photo nuclear reactions, and the spin and parity of the state are studied by measuring angular correlations of particles emitted from the photo nuclear reactions. Medium-energy polarized photons obtained from laser photons scattered off GeV electrons are very useful. Nuclear responses studied by photo nuclear reactions are used to evaluate neutrino/weak nuclear responses, i.e. nuclear beta and double beta matrix elements and neutrino nuclear interactions, and to verify theoretical calculations for them.

H. Ejiri; A. I. Titov; M. Boswell; A. Young

2013-11-10

372

Principles of nuclear magnetic resonance  

SciTech Connect

The basic principles of nuclear magnetic resonance (NMR) are discussed. The concepts presented include a qualitative quantum-mechanical approach to NMR spectroscopy and a classical-mechanical approach to time-dependent NMR phenomena (relaxation effects). The spectroscopic concepts discussed include absorption of radiation by matter, spin and energy quantization, chemical shift, and spin-spin splitting. The time-dependent phenomena include the concepts of T/sub 1/ and T/sub 2/, the spin-lattice and spin-spin relaxation time, and Fourier-tranform NMR spectroscopy.

Koutcher, J.A.; Burt, C.T.

1984-01-01

373

Nuclear moment measurements of Neutron-rich Aluminum Isotopes Using Spin-polarized RI beams: Determination of the Boundary of the 'Island of Inversion'  

SciTech Connect

The electric quadrupole moment Q for the ground state of 32Al has been measured using the {beta}-NMR technique. Spin-polarized 32Al nuclei were obtained from the fragmentation of 40Ar projectiles at E/A = 95 MeV/nucleon, and were implanted in a single crystal {alpha}-Al2O3 stopper. The quadrupole moment was deduced from the measured quadrupole coupling constant. The obtained value, |Q(32Alg.s.)| = 24(2) mb, was well reproduced by shell model calculations within the sd shell, indicating that 32Al is a normal sd-shell nucleus. The result is in sharp contrast to the strongly deformed nuclei 32Mg and 31Mg neighboring the 32Al isotope.

Kameda, D.; Ueno, H.; Yoshimi, A.; Kobayashi, Y.; Haseyama, T.; Ishihara, M. [RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Asahi, K. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); RIKEN, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Takemura, M.; Nagae, D.; Shimada, K.; Uchida, M.; Takase, K.; Arai, T.; Inoue, T.; Suda, S. [Department of Physics, Tokyo Institute of Technology, 2-12-1 Oh-okayama, Meguro-ku, Tokyo 152-8551 (Japan); Murata, J.; Kawamura, H. [Department of physics, Rikkyo University, 3-34-1 Nishi-Ikebukuro, Toshima, Tokyo 171-8501 (Japan); Watanabe, H. [Department of Nuclear Physics, Research School of Physical Sciences and Engineering, Australian National University, Canberra AT 0200 (Australia)

2007-06-13

374

High-spin studies and nuclear structure in three semi-magic regions of the chart: High-seniority states in Sn isotopes  

NASA Astrophysics Data System (ADS)

Two fusion-fission experiments have been performed and studied with the Euroball Ge array: 12C+ 238U at 90 MeV bombarding energy, and 18O + 208Pb at 85 MeV. Among the lot of new information extracted during the last decade, the latest results discussed here are the discovery of the high-spin states of 119-126Sn. The maximum value of angular momentum available in the ?h11/2 shell, i.e. for mid-occupation and the breaking of the three neutron pairs (seniority v = 6), has been identified in several tin isotopes. It is the first time that such high-seniority states are established in spherical nuclei.

Astier, Alain

2013-12-01

375

Transverse nuclear spin relaxation due to director fluctuations in liquid crystals. III. A slow-motional theory for the angular dependence in pulsed experiments  

NASA Astrophysics Data System (ADS)

In the previous article, we have proposed a slow-motional theory for second-order effects of director fluctuations on transverse spin relaxation of quadrupolar nuclei in liquid crystals [D. Frezzato, G.J. Moro, and G. Kothe, J. Chem. Phys. 119, 6931 (2003), preceding paper]. This methodology is now generalized to arbitrary orientations of director and magnetic field. The characteristic functions are evaluated for the free induction decay and the echo intensities in Carr-Purcell-Meiboom-Gill (CPMG) multipulse sequences. From the solution of the corresponding integral equations, the relative magnitude of first and second-order contributions can be assessed. This enables a complete characterization of the angular and pulse spacing dependent transverse relaxation rates observed in CPMG multipulse experiments.

Frezzato, Diego; Kothe, Gerd; Moro, Giorgio J.

2003-10-01

376

Inertia of Intrinsic Spin  

E-print Network

The state of a particle in space and time is characterized by its mass and spin, which therefore determine the inertial properties of the particle. The coupling of intrinsic spin with rotation is examined and the corresponding inertial effects of intrinsic spin are studied. An experiment to measure directly the spin-rotation coupling via neutron interferometry is analyzed in detail.

Bahram Mashhoon; Helmut Kaiser

2005-08-24

377

Spin flight research summary  

NASA Technical Reports Server (NTRS)

An extensive general aviation stall/spin research program is underway at the NASA Langley Research Center. Flight tests have examined the effects of tail design, wing leading edge design, mass distribution, and minor airframe modifications on spin and recovery characteristics. Results and observations on test techniques are presented for the first airplane in the program. Configuration changes produced spins varying from easily recoverable slow, steep spins to unrecoverable, fast flat spins.

Patton, J. M., Jr.; Stough, H. P., III; Dicarlo, D. J.

1979-01-01

378

Magnons, Spin Current and Spin Seebeck Effect  

NASA Astrophysics Data System (ADS)

When metals and semiconductors are placed in a temperature gradient, the electric voltage is generated. This mechanism to convert heat into electricity, the so-called Seebeck effect, has attracted much attention recently as the mechanism for utilizing wasted heat energy. [1]. Ferromagnetic insulators are good conductors of spin current, i.e., the flow of electron spins [2]. When they are placed in a temperature gradient, generated are magnons, spin current and the spin voltage [3], i.e., spin accumulation. Once the spin voltage is converted into the electric voltage by inverse spin Hall effect in attached metal films such as Pt, the electric voltage is obtained from heat energy [4-5]. This is called the spin Seebeck effect. Here, we present the linear-response theory of spin Seebeck effect based on the fluctuation-dissipation theorem [6-8] and discuss a variety of the devices. [4pt] [1] S. Maekawa et al, Physics of Transition Metal Oxides (Springer, 2004). [0pt] [2] S. Maekawa: Nature Materials 8, 777 (2009). [0pt] [3] Concept in Spin Electronics, eds. S. Maekawa (Oxford University Press, 2006). [0pt] [4] K. Uchida et al., Nature 455, 778 (2008). [0pt] [5] K. Uchida et al., Nature Materials 9, 894 (2010) [0pt] [6] H. Adachi et al., APL 97, 252506 (2010) and Phys. Rev. B 83, 094410 (2011). [0pt] [7] J. Ohe et al., Phys. Rev. B (2011) [0pt] [8] K. Uchida et al., Appl. Phys. Lett. 97, 104419 (2010).

Maekawa, Sadamichi

2012-02-01

379

Nuclear Magnetic Resonance Spectroscopy  

NSDL National Science Digital Library

This website serves as a primer for understanding the fundamentals of NMR spectroscopy. Plenty of useful figures and animations that enhance the understanding of nuclear spin, shielding, and how these phenomena serve as the basis for NMR.

2011-05-18

380

Anomalous electron spin decoherence in an optically pumped quantum dot  

NASA Astrophysics Data System (ADS)

We study the nuclear-spin-fluctuation induced spin decoherence of an electron (SDE) in an optically pumped quantum dot. The SDE is computed in terms of the steady distribution of the nuclear field (SDNF) formed through the hyperfine interaction (HI) with two different nuclear species in the dot. A feedback loop between the optically driven electron spin and the nuclear spin ensemble determines the SDNF [W. Yang and L. J. Sham, Phy. Rev. B 85, 235319(2012)]. Different from that work and others reviewed therein, where a bilinear HI, S?I?, between the electron (or hole) spin S and the nuclear spin I is used, we use an effective nonlinear interaction of the form S?I?I? derived from the Fermi-contact HI. Our feedback loop forms a multi-peak SDNF in which the SDE shows remarkable collapses and revivals in nanosecond time scale. Such an anomalous SDE results from a quantum interference effect of the electron Larmor precession in a multi-peak effective magnetic field. In the presence of a bilinear HI that suppresses the nuclear spin fluctuation, the non-Markovian SDE persists whenever there are finite Fermi contact interactions between two or more kinds of nuclei and the electron in the quantum dot.

Shi, Xiaofeng; Sham, L. J.

2013-03-01

381

Fusion-Fission and High-Spin Approach for the 78Ni Quest:. Nuclear Structure in the Neutron-Rich N=50 Region  

NASA Astrophysics Data System (ADS)

The spectroscopy of fission fragments, obtained by the 18O+208Pb fusion-fission reaction at 85 MeV bombarding energy, has been performed with the Euroball IV ?-array. Highspin states in many neutron-rich As, Se, Br, Kr and Rb of the 78Ni region nuclei have been identified for the first time. Several physical aspects which govern the nuclear structure in this mass region are underlined thanks to the new results.

Astier, Alain

2014-09-01

382

Experimental Heat-Bath Cooling of Spins  

E-print Network

Algorithmic cooling (AC) is a method to purify quantum systems, such as ensembles of nuclear spins, or cold atoms in an optical lattice. When applied to spins, AC produces ensembles of highly polarized spins, which enhance the signal strength in nuclear magnetic resonance (NMR). According to this cooling approach, spin-half nuclei in a constant magnetic field are considered as bits, or more precisely, quantum bits, in a known probability distribution. Algorithmic steps on these bits are then translated into specially designed NMR pulse sequences using common NMR quantum computation tools. The $algorithmic$ cooling of spins is achieved by alternately combining reversible, entropy-preserving manipulations (borrowed from data compression algorithms) with $selective$ $reset$, the transfer of entropy from selected spins to the environment. In theory, applying algorithmic cooling to sufficiently large spin systems may produce polarizations far beyond the limits due to conservation of Shannon entropy. Here, only selective reset steps are performed, hence we prefer to call this process "heat-bath" cooling, rather than algorithmic cooling. We experimentally implement here two consecutive steps of selective reset that transfer entropy from two selected spins to the environment. We performed such cooling experiments with commercially-available labeled molecules, on standard liquid-state NMR spectrometers. Our experiments yielded polarizations that $bypass$ $Shannon's$ $entropy$-$conservation$ $bound$, so that the entire spin-system was cooled. This paper was initially submitted in 2005, first to Science and then to PNAS, and includes additional results from subsequent years (e.g. for resubmission in 2007). The Postscriptum includes more details.

Gilles Brassard; Yuval Elias; José M. Fernandez; Haggai Gilboa; Jonathan A. Jones; Tal Mor; Yossi Weinstein; Li Xiao

2014-04-28

383

Triple-quantum two-dimentional {sup 27}Al magic-angle spinning nuclear magnetic resonance spectroscopic study of aluminosilicate and aluminate crystals and glasses  

SciTech Connect

A new two-dimensional magic-angle spinning NMR experiment using multiple-quantum coherence of half-integer quadrupolar nuclei was used to study {sup 27}Al sites in crystalline samples of leucite (KAlSi{sub 2}O{sub 6}), anorthite (CaAl{sub 2}Si{sub 2}O{sub 8}), and kyanite (Al{sub 2}SiO{sub 5}), as well as CaAl{sub 2}Si{sub 2}O{sub 8} glass and a magnesium aluminoborate glass. In the crystals, multiple sites are partially resolved and new results for isotropic chemical shifts and quadrupolar parameters are derived, using data collected at a single magnetic field. Data for both leucite and anorthite are consistent with previous results that correlate chemical shifts with mean intertetrahedral bond angle. Signal can be obtained from sites with quadrupolar coupling constants as large as 9 MHz, but intensities are reduced. In the aluminoborate glass, peaks for sites with different Al coordination numbers are well seperated. The lack of such features in CaAl{sub 2}Si{sub 2}O{sub 8} glass rules out the presence of significant quantities of AlO{sub 5} and AlO{sub 6} groups. 31 refs., 8 figs., 3 tabs.

Baltisberger, J.H. [Berea College, KY (United States)] [Berea College, KY (United States); Xu, Z.; Stebbins, J.F. [Stanford Univ., CA (United States)] [Stanford Univ., CA (United States); Wang, S.H.; Pines, A. [Lawrence Berkeley National Lab., CA (United States)] [Lawrence Berkeley National Lab., CA (United States)

1996-07-31

384

Spin microscope based on optically detected magnetic resonance  

DOEpatents

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

2009-10-27

385

Spin microscope based on optically detected magnetic resonance  

DOEpatents

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of impaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

2009-11-10

386

Visualization of an entangled channel spin-1 system  

SciTech Connect

Covariance matrix formalism gives powerful entanglement criteria for continuous as well as finite dimensional systems. We use this formalism to study a mixed channel spin-1 system which is well known in nuclear reactions. A spin-j state can be visualized as being made up of 2j spinors which are represented by a constellation of 2j points on a Bloch sphere using Majorana construction. We extend this formalism to visualize an entangled mixed spin-1 system.

Sirsi, Swarnamala; Adiga, Veena [Department of Physics, Yuvaraja's College, University of Mysore, Mysore-05 (India)

2010-08-15

387

Spin microscope based on optically detected magnetic resonance  

DOEpatents

The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

Berman, Gennady P. (Los Alamos, NM); Chernobrod, Boris M. (Los Alamos, NM)

2007-12-11

388

Spin, or actually: Spin and Quantum Statistics  

Microsoft Academic Search

The history of the discovery of electron spin and the Pauli principle and the mathematics of spin and quantum statistics are\\u000a reviewed. Pauli’s theory of the spinning electron and some of its many applications in mathematics and physics are considered\\u000a in more detail. The role of the fact that the tree-level gyromagnetic factor of the electron has the value g

Jürg Fröhlich

2009-01-01

389

Spin Rotation of Formalism for Spin Tracking  

SciTech Connect

The problem of which coefficients are adequate to correctly represent the spin rotation in vector spin tracking for polarized proton and deuteron beams in synchrotrons is here re-examined in the light of recent discussions. The main aim of this note is to show where some previous erroneous results originated and how to code spin rotation in a tracking code. Some analysis of a recent experiment is presented that confirm the correctness of the assumptions.

Luccio,A.

2008-02-01

390

Spin - or, actually: Spin and Quantum Statistics  

E-print Network

The history of the discovery of electron spin and the Pauli principle and the mathematics of spin and quantum statistics are reviewed. Pauli's theory of the spinning electron and some of its many applications in mathematics and physics are considered in more detail. The role of the fact that the tree-level gyromagnetic factor of the electron has the value g = 2 in an analysis of stability (and instability) of matter in arbitrary external magnetic fields is highlighted. Radiative corrections and precision measurements of g are reviewed. The general connection between spin and statistics, the CPT theorem and the theory of braid statistics are described.

Juerg Froehlich

2008-01-17

391

Double Nuclear Resonance and Nuclear Relaxation  

Microsoft Academic Search

The double nuclear resonance effect can be observed in materials in ; which nuclear spin-lattice relaxation occurs through paramagnetic imourities. A ; technique using Zeeman transitions of the distant nuclei to detect hyperfine ; transitions associated with nuclei at the paramagnetic impurities is preseated. ; (L.N.N.);

E. C. McIrvine; J. Lambe; N. Laurance; T. Cole

1962-01-01

392

Multiple-spin coherence transfer in linear Ising spin chains and beyond: numerically-optimized pulses and experiments  

Microsoft Academic Search

We study multiple-spin coherence transfers in linear Ising spin chains with nearest neighbor couplings. These constitute a model for efficient information transfers in future quantum computing devices and for many multi-dimensional experiments for the assignment of complex spectra in nuclear magnetic resonance spectroscopy. We complement prior analytic techniques for multiple-spin coherence transfers with a systematic numerical study where we obtain

Manoj Nimbalkar; Robert Zeier; Jorge L. Neves; S. Begam Elavarasi; Haidong Yuan; Navin Khaneja; Kavita Dorai; Steffen J. Glaser

2011-01-01

393

Subriemannian geodesics and optimal control of spin systems  

Microsoft Academic Search

Nuclear Magnetic Resonance (NMR) Spectroscopy in solution is an important modality for extracting structural information of macromolecules. In NMR spectroscopy, radio frequency electromagnetic pulses axe used to manipulate spin states of atomic nuclei. Pulse sequences that accomplish a desired spin control should be as short as possible in order to minimize the effects of thermal relaxation, and to optimize the

Navin Khaneja; Steffen Glaser; Roger Brockett

2002-01-01

394

Solid-State NMR Investigation of Paramagnetic Nylon-6 Clay Nanocomposites. 1. Crystallinity, Morphology, and the Direct Influence of Fe3+ on Nuclear Spins  

NSDL National Science Digital Library

Several exfoliated nylon-6/clay nanocomposites (NnCâs) were investigated and compared with pure nylon-6 using solid-state NMR, both proton and 13C. NnCâs had nominally 5 mass % clay and were generated both by blending and by in situ polymerization (IsP). Most of the studied NnCâs contained layered, naturally occurring montmorillonite clays having nonstoichiometric amounts of nonexchangeable Mg2+ and Fe3+ ions that substitute into octahedral Al3+ sites along the midplane of the 1-nm-thick clay layers. The Fe3+ ions impart a useful paramagnetism to the clay. Each Mg2+ ion leaves an embedded negative charge that must be neutralized with some cation at the surface of the clay. All clays were initially treated with a cationic so-called organic modifier (OM), often a substituted ammonium ion, which increases the clay layer spacing, attaching ionically to the surface of the clay layers. Clay is found to promote growth of the ç-crystalline phase of nylon-6 for both blended and IsP NnCâs; R-crystallites are characteristic of the pure nylon-6. Stability of the ç-phase to annealing at 214 °C was investigated. Conversion of ç- to R-crystallinity during annealing was minimal, except for an injection-molded IsP NnC, which had been exposed to a temperature of 295 °C during molding. This high processing temperature produced an irreversible change. An attempt was made to understand, at least qualitatively, the nature of the spectral density of magnetic fluctuations associated with the paramagnetic Fe3+ sites in the clay. For this purpose, we looked directly at the influence of Fe3+ on the 13C and proton observables in organically modified clays (OMC). We agree with other investigators that the spectral density of paramagnetic fluctuations at the surface of the clay is determined mainly by spin-exchange interactions between Fe3+ sites; thus, the spectral density can be altered by changing the Fe3+ concentration. Moreover, we find that the spectral density is very wide, having strong contributions all the way from mid-kHz fluctuations to MHz fluctuations near the proton Larmor frequencies. Significant variations in the R/ç ratio were also observed in the injection-molded disk, which reflect either a processing-induced heterogeneity in clay dispersion or a significant variation in cooling history from region to region. Proton spin diffusion and multiple-pulse methods were utilized to compare morphologies for a diamagnetic NnC and nylon-6 with the same thermal histories. Long spacing, crystallinity, and the mobility of the noncrystalline nylon-6 segments are very similar for NnCâs and nylon-6.

Vanderhart, D. L.; Asano, A.; Gilman, J. W.

2001-01-01

395

Spin relaxation in inhomogeneous quantum dot arrays studied by electron spin resonance  

NASA Astrophysics Data System (ADS)

Electron states in an inhomogeneous Ge/Si quantum dot array with groups of closely spaced quantum dots were studied by the conventional continuous-wave electron spin resonance and spin-echo techniques. We have found that the existence of quantum dot groups allows increasing the spin relaxation time in the system. The created structures permit us to change the effective localization radius of electrons by an external magnetic field. With the localization radius being close to the size of a quantum dot group, we obtain a fourfold increase in the spin relaxation time T1 as compared to conventional homogeneous quantum dot arrays. This effect is attributed to an averaging of the local magnetic fields produced by 29Si nuclear spins and a stabilization of the Sz polarization during the electron back-and-forth motion within a quantum dot group.

Zinovieva, A. F.; Stepina, N. P.; Nikiforov, A. I.; Nenashev, A. V.; Dvurechenskii, A. V.; Kulik, L. V.; Carmo, M. C.; Sobolev, N. A.

2014-01-01

396

A Large Sample Volume Magic Angle Spinning Nuclear Magnetic Resonance Probe for In-Situ Investigations with Constant Flow of Reactants  

SciTech Connect

A large-sample-volume constant-flow magic angle sample spinning (CF-MAS) NMR probe is reported for in-situ studies of the reaction dynamics, stable intermediates/transition states, and mechanisms of catalytic reactions. In our approach, the reactants are introduced into the catalyst bed using a fixed tube at one end of the MAS rotor while a second fixed tube, linked to a vacuum pump, is attached at the other end of the rotor. The pressure difference between both ends of the catalyst bed inside the sample cell space forces the reactants flowing through the catalyst bed, which improves the diffusion of the reactants and products. This design allows the use of a large sample volume for enhanced sensitivity and thus permitting in-situ 13C CF-MAS studies at natural abundance. As an example of application, we show that reactants, products and reaction transition states associated with the 2-butanol dehydration reaction over a mesoporous silicalite supported heteropoly acid catalyst (HPA/meso-silicalite-1) can all be detected in a single 13C CF-MAS NMR spectrum at natural abundance. Coke products can also be detected at natural 13C abundance and under the stopped flow condition. Furthermore, 1H CF-MAS NMR is used to identify the surface functional groups of HPA/meso-silicalite-1 under the condition of in-situ drying . We also show that the reaction dynamics of 2-butanol dehydration using HPA/meso-silicalite-1 as a catalyst can be explored using 1H CF-MAS NMR.

Hu, Jian Z.; Sears, Jesse A.; Mehta, Hardeep S.; Ford, Joseph J.; Kwak, Ja Hun; Zhu, Kake; Wang, Yong; Liu, Jun; Hoyt, David W.; Peden, Charles HF

2012-02-21

397

Multiple-spin coherence transfer in linear Ising spin chains and beyond: numerically-optimized pulses and experiments  

E-print Network

We study multiple-spin coherence transfers in linear Ising spin chains with nearest neighbor couplings. These constitute a model for efficient information transfers in future quantum computing devices and for many multi-dimensional experiments for the assignment of complex spectra in nuclear magnetic resonance spectroscopy. We complement prior analytic techniques for multiple-spin coherence transfers with a systematic numerical study where we obtain strong evidence that a certain analytically-motivated family of restricted controls is sufficient for time-optimality. In the case of a linear three-spin system, additional evidence suggests that prior analytic pulse sequences using this family of restricted controls are time-optimal even for arbitrary local controls. In addition, we compare the pulse sequences for linear Ising spin chains to pulse sequences for more realistic spin systems with additional long-range couplings between non-adjacent spins. We experimentally implement the derived pulse sequences in th...

Nimbalkar, Manoj; Neves, Jorge L; Elavarasi, S Begam; Yuan, Haidong; Khaneja, Navin; Dorai, Kavita; Glaser, Steffen J

2011-01-01

398

On Spin Hamiltonian fits to Mössbauer spectra of high-spin Fe(II) porphyrinate systems  

Microsoft Academic Search

Fits to Mössbauer spectra of high-spin iron(II) porphyrinates have been applied to the Fe(II) model compounds octaethylporphyrin(1,2-dimethylimidazole) and tetra-paramethoxyporphyrin(1,2-dimethylimidazole). Mössbauer spectra have been measured on these compounds at 4.2 K in large applied fields. Spin Hamiltonians were used for fitting both the electronic and nuclear interactions. The fits are done by adjusting the Hamiltonian parameters to simultaneously minimize the total

Charles E. Schulz; Chuanjiang Hu; W. Robert Scheidt

2007-01-01

399

On Spin Hamiltonian fits to Mössbauer spectra of high-spin Fe(II) porphyrinate systems  

Microsoft Academic Search

Fits to Mössbauer spectra of high-spin iron(II) porphyrinates have been applied to the Fe(II) model compounds octaethylporphyrin(1,2-dimethylimidazole) and tetra-paramethoxyporphyrin(1,2-dimethylimidazole). Mössbauer spectra have been measured on these compounds at 4.2 K in large applied fields. Spin Hamiltonians were used for fitting both the electronic and nuclear interactions. The fits are done by adjusting the Hamiltonian parameters to simultaneously minimize the total

Charles E. Schulz; Chuanjiang Hu; W. Robert Scheidt

2006-01-01

400

Structural characterization and physical properties of P2O5-CaO-Na2O-TiO2 glasses by Fourier transform infrared, Raman and solid-state magic angle spinning nuclear magnetic resonance spectroscopies.  

PubMed

Phosphate-based glasses have been investigated for tissue engineering applications. This study details the properties and structural characterization of titanium ultra-phosphate glasses in the 55(P(2)O(5))-30(CaO)-(25-x)(Na(2)O)-x(TiO(2)) (0?x?5) system, which have been prepared via melt-quenching techniques. Structural characterization was achieved by a combination of X-ray diffraction (XRD), and solid-state nuclear magnetic resonance, Raman and Fourier transform infrared spectroscopies. Physical properties were also investigated using density, degradation and ion release studies; additionally, differential thermal analysis was used for thermal analysis of these glasses. The results show that with the addition of TiO(2) the density and glass transition temperature increased whereas the degradation and ion release properties are decreased. From XRD data, TiP(2)O(7) and CaP(2)O(6) were detected in 3 and 5 mol.% TiO(2)-containing glasses. Magic angle spinning nuclear magnetic resonance results confirmed that as TiO(2) is incorporated into the glass; the amount of Q(3) increases as the amount of Q(2) consequently decreases, indicating increasing polymerization of the phosphate network. Spectroscopy results also showed that the local structure of glasses changes with increasing TiO(2) content. As TiO(2) is incorporated into the glass, the phosphate connectivity increases, indicating that the addition of TiO(2) content correlates unequivocally with an increase in glass stability. PMID:21930253

Kiani, Azadeh; Hanna, John V; King, Scott P; Rees, Gregory J; Smith, Mark E; Roohpour, Nima; Salih, Vehid; Knowles, Jonathan C

2012-01-01

401

Recent experimental advances in spin glasses  

SciTech Connect

We present a working definition and a general description of a spin glass. A number of different systems, including metals, semiconductors, and insulators, are discussed. This review presents the current status of experimental spin-glass research with special emphasis on the extent to which the results of this research yield information on spin dynamics. We review the salient features of a series of recent experimental results, published in the past five years, on the susceptibility, magnetization, heat capacity, high-pressure effects, phonon-thermal conductivity, neutron scattering, nuclear, electron, and muon spin resonance. The successful applications of the fractional exponential relaxation function to the frequency dependence of the susceptibility and the time dependence of the thermoremanent magnetization are demonstrated. Concerning the possible existence of the phase transition at the susceptibility cusp temperature, we summarize the experimental evidences. 179 references, 31 figures.

Huang, C.Y.

1983-01-01

402

Chemical state of boron in coal fly ash investigated by focused-ion-beam time-of-flight secondary ion mass spectrometry (FIB-TOF-SIMS) and satellite-transition magic angle spinning nuclear magnetic resonance (STMAS NMR).  

PubMed

The chemical states of boron in coal fly ash, which may control its leaching into the environment, were investigated by focused-ion-beam time-of-flight secondary ion mass spectrometry (FIB-TOF-SIMS) and satellite-transition magic angle spinning nuclear magnetic resonance (STMAS NMR) spectroscopy. The distribution of boron on the surface and in the interior of micron-sized fly ash particles was directly observed by FIB-TOF-SIMS. Coordination numbers of boron and its bonding with different atoms from particles of bulk samples were investigated by STMAS NMR. Boron in coal fly ash with relatively poor leaching characteristics appears as trigonal BO(3) and coexists with Ca and Fe at the outer layer of every particle and inside CaO-MgO particles. In contrast, boron in coal fly ash with better leaching characteristics appears as CaO- or MgO-trigonal BO(3) and tetragonal BO(4), and it is distributed only on the outer surface of each ash particle without showing any correlation with a particular element. PMID:20570315

Hayashi, Shun-ichi; Takahashi, Takafumi; Kanehashi, Koji; Kubota, Naoyoshi; Mizuno, Kaoru; Kashiwakura, Shunsuke; Sakamoto, Tetsuo; Nagasaka, Tetsuya

2010-08-01

403

Spin transport in bimetallocene  

NASA Astrophysics Data System (ADS)

I present a theoretical study on the spin-transport behavior of bimetallocenes of cobalt or nickel, wherein electronic communication between the two metal centers can be efficiently performed via a fulvalene ligand. The transmission of electrons in the bimetallocene connected to two gold electrodes was calculated using a first-principles density functional method. Spin transport was estimated from the difference between the transmissions of the spin-up and spin-down states. Results revealed that bicobaltocene has a perfect spin-filtering effect because the supply of excess electrons to the electronic state of ferrocene causes a split in the energy levels of the spin-up and spin-down states. As surmised, it was found that spin polarization was caused by strong interactions between the two metal centers via the fulvalene ligand. Furthermore, bicobaltocene exhibited a negative differential resistance at a relatively low bias voltage.

Matsuura, Y.

2013-09-01

404

Conceptual description Our contributions Coherent spin  

E-print Network

the electron and nuclear spin degrees of freedom. Mesoscopics in strongly correlated systems Topological Qubits physics arise in systems with strong electron-electron interactions. Such systems often give rise electron gas. In the past decade, experiments in 2D systems with strong interac- tions have uncovered

Plotkin, Steven S.

405

The Beauty of Spin  

E-print Network

I review recent developments in theoretical spin physics. Topics include pion production in nucleon-nucleon collisions, the implications of heavy quark spin symmetry for heavy hadron molecules, the nucleon electric dipole form factors and ab initio calculations of the width of hadron resonances. A few spin physics high-lights from experiments at the COSY accelerator are also discussed.

Ulf-G. Meißner

2010-12-04

406

SPINS Java Homepage  

NSDL National Science Digital Library

Spins is an interactive computer program that simulates Stern-Gerlach measurements on spin 1/2 and spin 1 particles. This software is used as part of the "Paradigms in Physics" curriculum. This can be used as an example to study general problems in quantum measurement and time dependence.

Mcintyre, David

2004-01-20

407

Non-equilibrium spin polarization via real-time control of spin fluctuations in a semiconductor nanowire  

NASA Astrophysics Data System (ADS)

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 [1, 2]. Here we demonstrate a similar control over a nanoscale ensemble of spins using the mechanical readout of magnetic resonance force microscopy (MRFM) [3]. We employ the exceptional sensitivity of MRFM to perform real-time measurement and control of an ensemble containing 10^5 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. 1. Vink, I. T. et al. Nature Phys. 5, 764 (2009). 2. Latta, C. et al. Nature Phys. 5, 758 (2009). 3. Budakian, R. et al. Science 307, 408 (2005).

Peddibhotla, Phani; Xue, Fei; Hauge, Ikaros; Bakkers, Erik; Poggio, Martino

2013-03-01

408

Nuclear Magnetic Resonance Coupling Constants and Electronic Structure in Molecules.  

ERIC Educational Resources Information Center

Theory of nuclear magnetic resonance spin-spin coupling constants and nature of the three types of coupling mechanisms contributing to the overall spin-spin coupling constant are reviewed, including carbon-carbon coupling (neither containing a lone pair of electrons) and carbon-nitrogen coupling (one containing a lone pair of electrons).…

Venanzi, Thomas J.

1982-01-01

409

A 23Na magic angle spinning nuclear magnetic resonance, XANES, and high-temperature X-ray diffraction study of NaUO3, Na4UO5, and Na2U2O7.  

PubMed

The valence state of uranium has been confirmed for the three sodium uranates NaU(V)O3/[Rn](5f(1)), Na4U(VI)O5/[Rn](5f(0)), and Na2U(VI)2O7/[Rn](5f(0)), using X-ray absorption near-edge structure (XANES) spectroscopy. Solid-state (23)Na magic angle spinning nuclear magnetic resonance (MAS NMR) measurements have been performed for the first time, yielding chemical shifts at -29.1 (NaUO3), 15.1 (Na4UO5), and -14.1 and -19 ppm (Na1 8-fold coordinated and Na2 7-fold coordinated in Na2U2O7), respectively. The [Rn]5f(1) electronic structure of uranium in NaUO3 causes a paramagnetic shift in comparison to Na4UO5 and Na2U2O7, where the electronic structure is [Rn]5f(0). A (23)Na multi quantum magic angle spinning (MQMAS) study on Na2U2O7 has confirmed a monoclinic rather than rhombohedral structure with evidence for two distinct Na sites. DFT calculations of the NMR parameters on the nonmagnetic compounds Na4UO5 and Na2U2O7 have permitted the differentiation between the two Na sites of the Na2U2O7 structure. The linear thermal expansion coefficients of all three compounds have been determined using high-temperature X-ray diffraction: ?a = 22.7 × 10(-6) K(-1), ?b = 12.9 × 10(-6) K(-1), ?c = 16.2 × 10(-6) K(-1), and ?vol = 52.8 × 10(-6) K(-1) for NaUO3 in the range 298-1273 K; ?a = 37.1 × 10(-6) K(-1), ?c = 6.2 × 10(-6) K(-1), and ?vol = 81.8 × 10(-6) K(-1) for Na4UO5 in the range 298-1073 K; ?a = 6.7 × 10(-6) K(-1), ?b = 14.4 × 10(-6) K(-1), ?c = 26.8 × 10(-6) K(-1), ?? = -7.8 × 10(-6) K(-1), and ?vol = -217.6 × 10(-6) K(-1) for Na2U2O7 in the range 298-573 K. The ? to ? phase transition reported for the last compound above about 600 K was not observed in the present studies, either by high-temperature X-ray diffraction or by differential scanning calorimetry. PMID:24350659

Smith, A L; Raison, P E; Martel, L; Charpentier, T; Farnan, I; Prieur, D; Hennig, C; Scheinost, A C; Konings, R J M; Cheetham, A K

2014-01-01

410

Spin-dependent parton distributions in the nucleon  

SciTech Connect

Spin-dependent quark light-cone momentum distributions are calculated for a nucleon in the nuclear medium. We utilize a modified NJL model where the nucleon is described as a composite quark-diquark state. Scalar and vector mean fields are incorporated in the nuclear medium and these fields couple to the confined quarks in the nucleon. The effect of these fields on the spin-dependent distributions and consequently the axial charges is investigated. Our results for the ''spin-dependent EMC effect'' are also discussed.

I.C. Cloet; W. Bentz; A.W. Thomas

2005-04-01

411

Influence of the pairing interaction at ultrahigh spin  

SciTech Connect

The pairing effect plays a very important role in nuclear phenomena. We analyze the influence of pairing interaction on angular momentum alignments and backbending frequencies near the ultrahigh spin ({Dirac_h}/2{pi}){omega}{approx_equal}0.8 MeV. Although the moment of inertia of rotational bands tends to be the same with or without pairing interaction, their angular momentum alignments and backbending frequencies still have large differences even at the ultrahigh spin region. For the normal orbitals, the alignment difference keeps almost constant from the larger spin region to the ultrahigh spin region. The high-jorbitals always cause drastic changes of alignment and lead to changes of backbending frequencies. Therefore, even at the ultrahigh spin region, to understand some nuclear phenomena, the pairing correlations should be included in some theoretical models.

Liu, S. X. [School of Physics, Peking University, Beijing 100871 (China); Center of Theoretical Nuclear Physics, National Laboratory of Heavy Ion Collisions, Lanzhou 730000 (China); Li, T.; Chen, B. R. [School of Physics, Peking University, Beijing 100871 (China)

2009-10-15

412

Slow spin relaxation in dipolar spin ice.  

NASA Astrophysics Data System (ADS)

Spin relaxation in dipolar spin ice Dy2Ti2O7 and Ho2Ti2O7 was investigated using the magnetocaloric effect and susceptibility. The magnetocaloric behavior of Dy2Ti2O7 at temperatures where the orientation of spins is governed by ``ice rules`` (T < Tice) revealed thermally activated relaxation; however, the resulting temperature dependence of the relaxation time is more complicated than anticipated by a mere extrapolation of the corresponding high temperature data [1]. A susceptibility study of Ho2Ti2O7 was performed at T > Tice and in high magnetic fields, and the results suggest a slow relaxation of spins analogous to the behavior reported in a highly polarized cooperative paramagnet [2]. [1] J. Snyder et al., Phys. Rev. Lett. 91 (2003) 107201. [2] B. G. Ueland et al., Phys. Rev. Lett. 96 (2006) 027216.

Orendac, Martin; Sedlakova, Lucia; Orendacova, Alzbeta; Vrabel, Peter; Feher, Alexander; Pajerowski, Daniel M.; Cohen, Justin D.; Meisel, Mark W.; Shirai, Masae; Bramwell, Steven T.

2009-03-01

413

A switchable controlled-NOT gate in a spin-chain NMR quantum computer  

Microsoft Academic Search

A method of switching a controlled-NOT gate in a solid-stae NMR quantum\\u000acomputer is presented. Qubits of I=1\\/2 nuclear spins are placed periodically\\u000aalong a quantum spin chain (1-D antiferromagnet) having a singlet ground state\\u000awith a finite spin gap to the lowest excited state caused by some quantum\\u000aeffect. Irradiation of a microwave tuned to the spin gap energy

Atsushi Goto; Tadashi Shimizu; Kenjiro Hashi; Hideaki Kitazawa

2002-01-01

414

Spin squeezing in an ensemble of quadrupolar nuclei NMR system  

E-print Network

We have characterized spin-squeezed states produced at a temperature of $26^\\circ{\\mathrm C}$ on a Nuclear Magnetic Resonance (NMR) quadrupolar system. The implementation is carried out in an ensemble of $^{133}$Cs nuclei with spin $I=7/2$ of a lyotropic liquid crystal sample. We identify the source of spin squeezing due to the interaction between the quadrupole moment of the nuclei and the electric field gradients internally present in the molecules. We use the spin angular momentum representation to describe formally the nonlinear operators that produce the spin squeezing. The quantitative and qualitatively characterization of the spin squeezing phenomena is performed through a squeezing parameter and squeezing angle developed for the two-mode BEC system, and, as well, by the Wigner quasi-probability distribution function. The generality of the present experimental scheme indicates its potential applications on solid state physics.

R. Auccaise; A. G. Araujo-Ferreira; R. S. Sarthour; I. S. Oliveira; T. J. Bonagamba; I. Roditi

2014-03-11

415

Building a spin quantum bit register using semiconductor nanowires.  

PubMed

This paper reviews recent advances in engineering spin quantum bits (qubits) in semiconductor quantum dots and describes an approach based on top-gated semiconductor nanowire devices. Fast electrical single-spin manipulation is achievable, in principle, using the spin-orbit interaction intrinsic to III-V materials, such as InAs, in concert with AC electric fields. Combined with sub-nanosecond gate control of the nearest-neighbor exchange interaction and spin readout by spin-to-charge conversion, a fully electrical solid-state quantum processor is within reach. We outline strategies for spin manipulation, robust readout and mitigation of decoherence due to nuclear fields that, when combined in a single device, should give a viable multi-qubit testbed and a building block for larger scale quantum devices. PMID:20208115

Baugh, J; Fung, J S; Mracek, J; LaPierre, R R

2010-04-01

416

SPIN POLARIZED HELIUM3, A PLAYGROUND IN MANY DOMAINS OF PHYSICS  

Microsoft Academic Search

This article gives a survey of the different methods which can be used to polarize the nuclear spin of helium-3. These techniques are particularly discussed in relation to the production of polarized helium-3 targets for nuclear physics experiments, such as electron or proton scattering and neutron spin filters. Some emphasis is given to the development of new powerful solid state

M. LEDUC

1990-01-01

417

Optimal control of coupled spin dynamics in the presence of relaxation  

Microsoft Academic Search

In this thesis, we study methods for optimal manipulation of coupled spin dynamics in the presence of relaxation. We use these methods to compute analytical upper bounds for the efficiency of coherence and polarization transfer between coupled nuclear spins in multidimensional nuclear magnetic resonance (NMR) experiments, under the presence of relaxation. We derive relaxation optimized pulse sequences which achieve or

Dionisis Stefanatos

2005-01-01

418

QM Spins Program  

NSDL National Science Digital Library

The QM Spins program simulates the quantum-mechanical measurement of spin-1/2 and spin-1 particles. It is distributed as a ready-to-run (compiled) Java archive. Double clicking the qm_spins.jar file will run the program if Java is installed. The default simulation shows the result of measuring the z component of spin on a beam of spin-1/2 particles with a random (or statistical) mixture of spin orientations. Additional initial states and other measurements can be specified using the Design and/or Initialize menu items. QM Spins is one of 5 Open Source Physics programs that model quantum mechanical measurement. The original program, Spins, was written for the Macintosh by Daniel Schroeder and Thomas Moore and was then ported to Java by David McIntyre. We have made extensive modifications to the Java version of the SPINS program. Additional Open Source Physics programs for quantum mechanics are available. They can be found by searching ComPADRE for Open Source Physics, OSP, or Superposition.

Christian, Wolfgang

2008-05-14

419

Effectiveness of classical spin simulations for describing NMR relaxation of quantum spins  

E-print Network

We investigate the limits of effectiveness of classical spin simulations for predicting free induction decays (FIDs) measured by solid-state nuclear magnetic resonance (NMR) on systems of quantum nuclear spins. The specific limits considered are associated with the range of interaction, the size of individual quantum spins and the long-time behavior of the FID signals. We compare FIDs measured or computed for lattices of quantum spins (mainly spins 1/2) with the FIDs computed for the corresponding lattices of classical spins. Several cases of excellent quantitative agreement between quantum and classical FIDs are reported along with the cases of gradually decreasing quality of the agreement. We formulate semi-empirical criteria defining the situations, when classical simulations are expected to accurately reproduce quantum FIDs. Our findings indicate that classical simulations may be a quantitatively accurate tool of first principles calculations for a broad class of macroscopic systems, where individual quantum microscopic degrees of freedom are far from the classical limit.

Tarek A. Elsayed; Boris V. Fine

2014-09-29

420

Study of lignification by noninvasive techniques in growing maize internodes. An investigation by Fourier transform infrared cross-polarization-magic angle spinning 13C-nuclear magnetic resonance spectroscopy and immunocytochemical transmission electron microscopy.  

PubMed Central

Noninvasive techniques were used for the study in situ of lignification in the maturing cell walls of the maize (Zea mays L.) stem. Within the longitudinal axis of a developing internode all of the stages of lignification can be found. The synthesis of the three types of lignins, p-hydroxyphenylpropane (H), guaiacyl (G), and syringyl (S), was investigated in situ by cross-polarization-magic angle spinning 13C-solid-state nuclear magnetic resonance, Fourier transform infrared spectroscopy, and immunocytochemical electron microscopy. The first lignin appearing in the parenchyma is of the G-type preceeding the incorporation of S nuclei in the later stages. However, in vascular bundles, typical absorption bands of S nuclei are visible in the Fourier transform infrared spectra at the earliest stage of lignification. Immunocytochemical determination of the three types of lignin in transmission electron microscopy was possible thanks to the use of antisera prepared against synthetic H, G, and the mixed GS dehydrogenative polymers (K. Ruel, O. Faix, J.P. Joseleau [1994] J Trace Microprobe Tech 12: 247-265). The specificity of the immunological probes demonstrated that there are differences in the relative temporal synthesis of the H, G, and GS lignins in the different tissues undergoing lignification. Considering the intermonomeric linkages predominating in the antigens used for the preparation of the immunological probes, the relative intensities of the labeling obtained provided, for the first time to our knowledge, information about the macromolecular nature of lignins (condensed versus noncondensed) in relation to their ultrastructural localization and development stage. PMID:9232887

Joseleau, J P; Ruel, K

1997-01-01

421

Burst Oscillations: Watching Neutron Stars Spin  

NASA Technical Reports Server (NTRS)

It is now almost 15 years since the first detection of rotationally modulated emission from X-ray bursting neutron stars, "burst oscillations," This phenomenon enables us to see neutron stars spin, as the X-ray burst flux asymmetrically lights up the surface. It has enabled a new way to probe the neutron star spin frequency distribution, as well as to elucidate the multidimensional nature of nuclear burning on neutron stars. I will review our current observational understanding of the phenomenon, with an eye toward highlighting some of the interesting remaining puzzles, of which there is no shortage.

Strohmayer, Tod

2010-01-01

422

What is Electron Spin?  

E-print Network

distributed for no-profit educational & research purposes. Not for commercial use. An isolated static electron in free space is not a fixed particle at rest. It is always oscillating in a SHM in its own electromagnetic inertia field, rest frame even at zero kelvin temperature. This is non-thermal, standing wave, resonance Compton frequency, oscillation along a linear path or, along an elliptical or a circular (clockwise or anti-clockwise) path, corresponding to the electron’s intrinsic magnetic moment (spin up or spin down). An electron with spin behaves like a tiny magnet. Intrinsic spin does not imply that a subatomic particle is spinning like a toytop about its axis. A hypothetical electron without a charge is like the bob of a simple pendulum without a string. INTRINSIC SPIN & ORBITAL ANGULAR MOMENTUM

Kamal L Rajpal; Copyright Kamal; L Rajpal; All Rights; Reserved May