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Sulfur‐33(33S) stable‐isotope labeled taurine, 2‐aminoethanesulfonic acid, has been synthesized, and a series of solution and solid‐state 33S nuclear magnetic resonance (NMR) experiments at 14.1 and 18.8 T, respectively, have been carried out at room temperature. The single peak of a solution 33S NMR spectrum in 0.1‐mM [33S]‐taurine in D2O can be observed with the signal‐to‐noise (S/N) ratio of 9 in 40,000 scans, which paves the way toward in vivo analysis of pharmacokinetics and metabolism of 33S‐labeled taurine. Undistorted magic‐angle‐spinning (MAS) and static 33S NMR spectra of polycrystalline [33S]‐taurine are observed with sufficient S/N ratios for analysis, and the magnitudes of 33S EFG and CS tensors can be obtained. [ABSTRACT FROM AUTHOR]

The chemical order and disorder of solids have a decisive influence on the material properties. There are numerous materials exhibiting chemical order/disorder of atoms with similar X-ray atomic scattering factors and similar neutron scattering lengths. It is difficult to investigate such order/disorder hidden in the data obtained from conventional diffraction methods. Herein, we quantitatively determined the Mo/Nb order in the high ion conductor Ba7Nb4MoO20 by a technique combining resonant X-ray diffraction, solid-state nuclear magnetic resonance (NMR) and first-principle calculations. NMR provided direct evidence that Mo atoms occupy only the M2 site near the intrinsically oxygen-deficient ion-conducting layer. Resonant X-ray diffraction determined the occupancy factors of Mo atoms at the M2 and other sites to be 0.50 and 0.00, respectively. These findings provide a basis for the development of ion conductors. This combined technique would open a new avenue for in-depth investigation of the hidden chemical order/disorder in materials. Chemical order/disorder in materials can be difficult to determine for atoms with similar X-ray scattering factors and neutron scattering lengths. Here authors use resonant XRD and NMR to elucidate hidden Mo/Nb chemical order in disordered hexagonal perovskite Ba7Nb4MoO20, with Mo atoms found to be localized near the ion-conducting oxygen deficient layer. [ABSTRACT FROM AUTHOR]

We present a scheme of surface-sensitive nuclear magnetic resonance in optically pumped semiconductors, where an NMR signal from a part of the surface of a bulk compound semiconductor is detected apart from the bulk signal. It utilizes optically oriented nuclei with a long spin-lattice relaxation time as a polarization reservoir for the second (target) nuclei to be detected. It provides a basis for the nuclear spin polarizer [IEEE Trans. Appl. Supercond. 14:1635, ], which is a polarization reservoir at the surface of the optically pumped semiconductor that polarizes nuclear spins in a target material in contact through the nanostructured interfaces. [ABSTRACT FROM AUTHOR]

We describe an optical-pumping double-resonance NMR system equipped with a single-coil double-tuning (XY) probe with an optical fiber attachment working in a helium-gas flow cryostat. The system enables simultaneous control of an infrared light and two radio-frequency fields irradiated to a sample, so that solid-state NMR techniques such as spin locking, decoupling, and cross polarization can be invoked under the optical-pumping condition. A nuclear hyperpolarization transfer experiment in optically pumped InP:Fe is presented. [ABSTRACT FROM AUTHOR]

We have been developing an optical pumping nuclear spin polarizer (OPNSP) to enhance nuclear magnetic resonance (NMR) signals from small amount of nano- and biological materials. In this scheme, a semiconductor and a target (nano- or biological) material are in close contact with each other, and high nuclear spin polarization in the semiconductor created by the optical pumping method is transferred to the nuclei in the target material by a cross-polarization at the interfaces and a spin diffusion inside the target material. As a result, high nuclear spin polarization is realized in the target material. In this paper, we present profiles of the nuclear spin polarization in the target material of the OPNSP calculated for the multilayered and multi-columnar configurations, from which suitable designs of the OPNSP to achieve high nuclear polarization in the target materials are discussed. [ABSTRACT FROM AUTHOR]

We have developed an optical pumping NMR system for semiconductors as an effective nuclear spin polarizer for a solid-state NMR quantum computer. The system was successfully applied to enhance 31P nuclear spin polarization in InP doped with Fe, and the enhancement of the 31P NMR signal by more than two orders of magnitude was achieved. We also observed the strong dependences of the enhancement on the helicity and the photon energy of incident light. The most effective enhancement was achieved with the helicity σ+ and photon energy smaller than the bandgap by 10∼15 meV. [Copyright &y& Elsevier]

Abstract: We have developed a dynamic nuclear polarization system based on the optical pumping NMR method. It consists of an NMR spectrometer, laser and optical system, optical-pumping double-resonance probe, cryostat and superconducting magnet. The double-resonance probe newly developed for this system is of a top-loading type, characterized by a single-coil double-tuning tank circuit with traps. The system allows simultaneous control of two radio-frequency fields and a light beam irradiated to samples, enabling us to perform cross-polarization experiments under the optical pumping condition. As a test of the system, a cross-polarization experiment has been performed with indium phosphide doped with iron. [Copyright &y& Elsevier]

Homogeneity and stability of a Bitter-type resistive magnet of National Institute for Material Science (NIMS) have been investigated at fields up to 23.5 T by means of NMR. The field homogeneity is 100 ppm over a 5 mm DSV. The field instability observed at 23.5 T contains, at least, two contributions; 1) 50 Hz fluctuations with an amplitude of 100 ppm, 2) long term drift at the rate of 50 ppm/hr. The magnet power supply may have a prime responsibility for the field fluctuations. We need an improvement of the power supply system to achieve a high resolution solid-state NMR measurement which may require stability of 10 ppm/hr. Possible applications of such a high field NMR may cover a wide range of inorganic materials including catalyzes, which consist of quadrupolar nuclei like Al, B, Ca, Cu, O, Ti, etc. We can expect that the spectra of quadrupolar nuclei would be simplified remarkably by such a high field magnet. [ABSTRACT FROM AUTHOR]

Solid-state NMR measurements at 30 T have been performed with a hybrid magnet of National Institute for Materials Science. Spectral resolution less than 3 ppm was confirmed by 79Br magic-angle-spinning (MAS)NMR measurements of a reference material KBr. A small sample and an aluminum metal shield were used to reduce the effects of field inhomogeneity and fluctuation. As an example of application for an industrial material, 27AlMASNMR of a refractory mortar was demonstrated. [ABSTRACT FROM AUTHOR]

Magnetic field homogeneity and stability of a Bitter type resistive magnet of National Institute for Materials Science (NIMS) have been examined at fields up to 23.5 T by means of NMR. The field homogeneity is 100 ± 10 ppm over a 5 mm DSV (diameter of spherical volume), being independent of field strength. The field instability observed at 23.5T contains, at least, two contributions; 1) a periodic oscillation of frequency 50 ± 1 Hz and amplitude 100 ± 25 ppm, and 2) a drift at a typical rate of 50 ± 20 ppm/h. The magnet power supply seems to be primarily responsible for both instabilities. [ABSTRACT FROM AUTHOR]

An abstract of the article "Development of a Flux Stabilizer for Solid-state Nuclear Magnetic Resonance with a Hybrid Magnet," by Kenjiro Hashi and colleagues is presented.

• A solid-state 197Au NMR spectrum of gold metal could be observed at room temperature. • A single peak at 13.937275 MHz ± 25 Hz is observed at 18.79666 T, from which the Knight shift is determined to be 0.11%. • The Knight shift at 4 K, reported in 1969, is redefined with the present results and modern physical constants. Solid-state 197Au static nuclear magnetic resonance (NMR) spectra of gold metal, detected at 18.79666 T and at room temperature, have been presented. Thermal annealing process plays an essential role for observation of the 197Au NMR signals. A single peak at 13.937275 MHz ± 25 Hz is observed and the Knight shift at room temperature is determined to be 0.11 %. The Knight shift at 4 K is redefined to be 0.07 %, using the modern physical constants. [Display omitted] [ABSTRACT FROM AUTHOR]

Abstract: The indirect nuclear spin–spin interaction tensor between neighboring 113,115In–31P spins in Fe-doped InP semiconductor has been studied by 31P NMR spectra measured using CP of 113In→ 31P and 115In→ 31P under slow MAS condition. The isotropic (J iso) and anisotropic (J aniso =2/3[J ∥ − J ⊥]) parts of the indirect interaction tensor are obtained from the spectral simulation. The acceptable combinations of these values are found to be as follows: (J iso, J aniso)=(224±5, 500±100Hz) or (−224±5, 2100±100Hz). Although, the coupling constants estimated in this study are slightly different from previously reported values of ∣J iso∣=350Hz, J aniso =1298Hz [M. Engelsberg, R.E. Norberg, Phys. Rev. B 5 (1972) 3395] and of ∣J iso∣=225±10, J aniso =(813±50) or (1733±50)Hz [M. Tomaselli et al., Phys. Rev. B 58 (1998) 8627], all of these has the trend that J aniso is rather larger than J iso. [Copyright &y& Elsevier]

We have developed a 920-MHz NMR system and performed the proton NMR measurement of H2O and ethylbenzene using the superconducting magnet operating at 21.6 T (920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high resolution NMR. [Copyright &y& Elsevier]

In Ti-based Ziegler-Natta catalysts (ZNCs), disagreements exist concerning which lateral surface of the MgCl 2 support adsorbs Ti species so as to be an active site for the catalysis of polymerization. In the present paper, we investigated the local structure of TiCl 4 adsorbed onto the surface of MgCl 2 by 47,49Ti solid-state nuclear magnetic resonance (NMR) spectra at 21.8 T along with density functional theory (DFT) calculations. The magic-angle-spinning NMR spectrum of the TiCl 4 /MgCl 2 adduct sample prepared by 20 h of milling, which exhibited broadened and shifted peaks compared to that of the sample without milling, was simulated by a Czjzek model considering the distribution of quadrupole interaction parameters. The electric field gradient and chemical shielding tensors of 49Ti were obtained via DFT calculations for model molecules of TiCl 4 , 2TiCl 4 , and Ti 2 Cl 8 adsorbed onto the (110), (104), and (104)-step defect surfaces of MgCl 2. By comparing the obtained NMR parameters, the 47,49Ti NMR spectrum of the milled sample was assigned to TiCl 4 adsorbed onto the (104) surface of MgCl 2 , which may not be a principal component of adsorption. Image 1 • 47,49Ti solid state NMR spectra of Ziegler-Natta catalysts. • Spectral simulation using a Czjzek distribution model. • DFT calculations of EFG and CSA tensors for some model molecules. • Assignment of 47,49Ti peaks to TiCl 4 adsorbed onto (104) of MgCl 2. [ABSTRACT FROM AUTHOR]

We have developed a 920 MHz NMR system and performed the proton NMR measurement of ethylbenzene and water using the superconducting magnet operating at 21.6 T (920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high-resolution NMR. The sensitivity has been examined by 1H NMR of 0.1% ethylbenzene in Wilmad 555 tube and obtained the signal-to-noise ratio as S/N=2981, which is the highest record, to our knowledge, among the room temperature measurements. [Copyright &y& Elsevier]

We report a23Na and27A1 nuclear magnetic resonance (NMR) investigation of low-silica X(LSX) zeolite with chemical formula Na12Al12Si12O48(Na12-LSX) loaded with n additional guest sodium atoms. Nan /Na12-LSX exhibits an insulator-to-metal transition around n=11.6, which is accompanied by a significant enhancement of bulk magnetic susceptibility. Paramagnetic moments are in the metallic Na12/Na12-LSX thermally activated with an activation energy of around 0.1 eV. Simultaneously a new shifted component appears in the23 Na NMR, whose large and positive NMR shift scales with bulk magnetic susceptibility. Its spin-lattice relaxation rate 1/ T1 is governed by the local-field fluctuations characterized by the same activation energy as obtained from the bulk magnetic susceptibility data. The time scale of these fluctuations is typical for atomic motions, which suggest strong electron-phonon coupling, a hallmark of polaron states. The insulator-to-metal transition in Nan/Na12-LSX is thus discussed within a polaron model. [ABSTRACT FROM AUTHOR]

Abstract: F atoms bonding to paramagnetic/conductive graphene layers in accepter-type graphite intercalation compounds (GICs) are analyzed using very fast magic angle spinning nuclear magnetic resonance, which is applied for the first time on 19F nuclei to investigate paramagnetic materials. In the bis(trifluoromethylsulfonyl)imide(TFSI)-doped GIC, C–F bonds between fluorine atoms and graphene layers conform to a weak bonding of F to the graphene sheets. TFSI anions intercalated in the GIC do not show overall molecular motion; even at room temperature only the CF3 groups rotate. [Copyright &y& Elsevier]