Hyperfine fields in Fe crystal detected by β-emitting12N

Hyperfine magnetic fields in a single crystal Fe were measured by use of asymmetric decay and NMR detection of spin polarized -emitting¹²N.     

Precise measurement of quadrupole moment of8B by use of a modified β-NMR

The nuclear quadrupole moment of⁸B(I =2⁺,T _1/2=769 ms) has been determined by use of a modified -NMR detection as |Q(⁸B)|=68.3±2.1 mb. A field gradient was obtained in a single crystal Mg at room temperature.     

Development of β-NMR and β-NQR

The β-NMR (nuclear magnetic resonance) and β-NQR (nuclear quadrupole resonance) technique and its ex-perimental set-up have been developed for the first time in China. The lifetime, magnetic moment and spin polarization of ^12B were determ/ned. The experimental results show the reliability of this newly developed β-NMR and β-NQR set-up.     

Development of the pulse NMR method utilizing the short-lived β-emitter 12 B

Measurements of the spin-spin relaxation time T ₂ of the short-lived $\upbeta $ -emitter $^{12}B (I^{\uppi }$ = 1^?+?, T _1/2 = 20 ms) in Si have been performed. By applying the spin echo method to $\upbeta $ -NMR measurements, the intrinsic T ₂ for ¹²B in Si was successfully determined with the effect of the static magnetic field inhomogeneity removed. The temperature dependence of T ₂ for ¹²B in Si shows that T ₂ becomes longer with increasing temperature, which seems to reflect the effect of motional narrowing.     

Measurement of nuclear moments and radii by collinear laser spectroscopy and by β-NMR spectroscopy

Experiments using laser spectroscopy and nuclear magnetic resonance techniques have been performed at ISOLDE on the unstable isotopes of several light elements. The results include nuclear ground state spins, magnetic dipole and electric quadrupole moments, and the behaviour of mean square nuclear charge radii within isotopic strings. These give important information about the nuclear structure at shell closures and close to the drip lines. This revised version was published online in July 2006 with corrections to the Cover Date.     

New nuclear quadrupole resonance technique in β-NMR

The -NMR technique has been modified in order to detect efficiently the nuclear quadrupole effects in the NMR spectra. -NMR is detected as a function of coupling frequency; all RFs that correspond to the coupling frequency were applied simultaneously.     

Development of rotating magnetic field system for the β-NMR method

A rotating magnetic field system has been developed to determine the sign of magnetic (μ) and quadrupole (Q) moments by means of the β-ray-detected nuclear magnetic resonance (β-NMR) method. The rotating magnetic field is obtained using two crossed Helmholtz-like coils at right angles. The phase angles of the alternating currents for the two coils are shifted by 90°. Thus the resulting magnetic field is circularly polarized. By the adjustment of the phase-angle difference, a right- or left-circularly polarized magnetic field is produced. Productions of right- or left-rotating magnetic fields including a linear component were confirmed using pickup-coils.     

Precise measurement of the quadrupole moment of β-emitting12B

Hyperfine interactions of¹²B(I ,T _1/2=21 ms) implanted in the substitutional site of B atoms (stable) in a (single crystal like) BN (hexagonal) was studied by use of a -NMR detection. For efficient and simple measurements, the conventional -NMR has been modified as a new nuclear quadrupole resonance technique (NNQR). For the present case with the nuclear spinI=1 the detection efficiency is improved about 30 times compared with the one with the old method. The quadrupole moment of¹²B was determined precisely as ¦Q(¹²B; 1⁺)¦=13.21±0.26 mb.     

Optical polarization of neutron-rich sodium isotopes and β-NMR measurements of quadrupole moments

The nuclear quadrupole moments of neutron-rich sodium isotopes are being investigated with the help of in-beam polarization by optical pumping in combination with-NMR techniques. First measurements have yielded the quadrupole splittings of NMR signals in the lattice of LiNbO₃ for the isotopes²⁶Na,²⁷Na and²⁸Na. Interaction constants and ratios of the electric quadrupole moments are derived. In view of future experiments,-decay asymmetries for the sequence of isotopes up to theN=20 neutron shell closure,^26–31Na, have been measured.     

Erratum to: Hydrodynamic dispersion in β-lactoglobulin gels measured by PGSE NMR

The displacement scale dependent molecular dynamics of solvent water molecules flowing through β-lactoglobulin gels are measured by pulse gradient spin echo (PGSE) nuclear magnetic resonance (NMR). Gels formed under different p H conditions generate structures which are characterized by magnetic resonance imaging (MRI) and PGSE NMR measured dynamics as homogeneous and heterogeneous. The data presented clearly demonstrate the applicability of the theoretical framework for modeling hydrodynamic dispersion to the analysis of protein gels.     

Description of the Properties of nuclei far from βstability line in relativistic Hartree approach

In the usual relativistic mean field(RMF) calculation of stable nuclei, the tensor coupling of ρ meson is not taken into account. It is necessary to clarify thecontribution of the tensor coupling of ρ meson when the RMF is extended to nucleifar from β stability line. The tensor coupling of ρ meson is included and its effectis discussed in the present work.     

Hyperfine interactions of polarized β-emitting12B and12N in Si,Ge, and GaP

Using a nuclear reaction, the polarized short-lived -emitters¹²B and¹²N were implanted into Si, Ge, and GaP crystals. Hyperfine fields were studied via both NMR techniques and an external magnetic holding field H_ext on-off techniques in an H_ext range 0–8 kG and a temperature range 100–1000 K. No significant NMR signal was observed between 2 and 30 MHz for¹²N in Si and Ge despite maintenance of 60% polarization at T100 K and H_ext>4 kG, whereas for¹²B in Si at T>800 K almost full polarization was found at the Larmor frequency.     

C-13 NMR Investigation of Cellobiose in the Presence and Absence of β-Glucosidase

T1(C-13) NMR measurements of cellobiose in aqueous solutions at pH=5 in the presence and absence of enzyme β-glucosidase detected at T=276°K a fast interaction between cellobiose and the enzyme at C1′α level of the disaccharide molecule. T1(C-13) measurements of equal solutions of cellobiose in the presence and absence of EDTA at the same temperatures suggest also a competitive interaction of cellobiose, at C1′α level, with EDTA complexed with a metal ion. T1 data justify a nearly spherical shape of cellobiose in solution.     

A Study of Antiferromagnetic Ordering in β-FeF3·3H2O by the Use of the NMR Method

The present work cites the investigation results of local magnetic fields on ¹H and ¹⁹F nuclei and spin ordering in β-FeF₃·3H₂O. In the structure of this compound (space group P4₂/n, a=7.846 Å, c=7.754 Å, z=4^1,2) Fe atoms are bonded via bridged F atoms (1) in infinite chains along the /001/ axis. With such positioning, in which two paramagnetic atoms are separated by a diamagnetic atom (F, O, C1 and others) there is a possibility for indirect (superexchange) interaction. Linear chains … Fe - F - Fe - F - Fe - F … are separated from each other by F(2) atoms and water molecules H₂O (1) and H₂O (2), so that exchange between neighboring Fe atoms from various chains is ostensibly much encumbered.     

Orientation of199mHg by optical pumping detected by γ-radiation anisotropy

^199mHg was produced and mass separated at the ISOLDE facility (CERN). Nuclear orientation achieved by optical pumping via the resonance line 6s ^{2 1} S ₀→6s6p ³ P ₁,λ=2537Å was monitored by means of the anisotropy of theγ-radiation emitted in the cascade^199mHg(I=13/2⁺) $${}^{199m}Hg(I = 13/2^ + )\xrightarrow[{M4}]{}{}^{199*}Hg(I = 5/2^ - )\xrightarrow[{E2}]{}{}^{199}Hg(I = 1/2^ - ).$$ ^199*Hg(I=5/2^?)¹⁹⁹Hg(I=1/2^?). Maximum anisotropies of 35% (2,8%) were found in the M4 (E2) transition. A Zeeman scanning of the³ P ₁ state yielded the positions ofF=13/2 and theF=15/2 hfs components relative to the reference isotope²⁰⁴Hg at 15.13 (15) GHz and ?2.86 (15) GHz respectively. Isotopic shift and the quadrupole interaction constant were deduced from these values using the knownA factor.δv ^199m/2O4=v ^2O4?v ^199m=12.20 (16) GHzB=?0.86 (25) GHz. From theB factor the spectroscopic quadrupolment was calculated asQ _s =1.54 (44) barn.     

Studies on the Formation of β-Cyclodextrin/Alkylcobaloxime Inclusion Complexes by Using NMR Methods

Abstract

It has been established that alkylcobaloxime(R=i-C₄H₉, n-C₄H₉, n-C_sH₁₁, c-C₆H₁₁, PhCH₂) and β-cyclodextrin form a kind of 1: 1 inclusion complexes in aqueous solution by ¹H NMR spectroscopy. Ka and ?ΔG^θ were calculated according to chemical shift changes of different probe protons. The stability constant(Ka) has been found increasing in the order: PhCH₂ > n-C₅H₁₁ > c-C₆H₁₁ > i-C₄H₉ > n-C₄H₉.     

Enantiomeric Composition of Chiral β-Hydroxylamides by 1H NMR Spectroscopy Using Chiral Solvating Agent

Studies of the perturbing effect of the trifluoromethylanthryl carbinol used as chiral solvating agent (CSA) upon the ¹H NMR spectra of chiral α-O-substituted β-hydroxylamides demonstrated the ability of this fluoroalcohol to afford diastereomeric solvates with these solutes. Thus, for all the tested amides, there is at least one possibility to proceed to their enantiomeric discrimination by ¹H NMR using CSA. The method was developed to determine (later and indirectly) a possible chiral recognition during in vitro enzymatic hydrolysis in locust biological tissues of N-acylaziridines conceived as proinsecticides of carboxylic acids, in view to eventually optimize their efficiency.     

In-plane magnetic texture of sputtered amorphous Fe60B40 detected by Mössbauer spectroscopy

Angular investigation of Mössbauer line intensities has been performed on a sputtered sample of amorphous Fe₆₀B₄₀. Accurate data, obtained using linear combination of standard spectra, reveal in-plane magnetic texture of the material.     

13C NMR Chemical Shift of β-Alkoxyvinylketones: II. Empirical Substituent Effects in β-Aryl-β-Methoxyvinyltrihalomethylketones

Evaluation by empirically derived equations for the substituent effect (α,β,γ,δ) on the ¹³C NMR chemical shifts for C-1, C-2, C-3 and C-4 in β-aryl-β-methoxyvinylhalomethylketones 1a-g to 2a-g [R³C(O)-CH=C(Ar)-OMe, where R³ = CCl₃, CF₃ and Ar = p-YC₆H₄ (Y = H, Me, MeO, F, Cl, Br, NO₂)], taking as reference the β-ethoxyvinyltrichloromethylketone (3), is reported. From the calculated values for the α,β,γ,δ effects for each substituent it was possible to estimate the chemical shift of each carbon of the compounds 1,2. The ¹³C chemical shifts of the C-1, C-2, C-3, C-4 of these compounds, can be estimated with good to rasoable precision: 84% of the calculated chemical shifts are found to be within ±1.0ppm, and 100% are found to be within ±1.5ppm. The Y-Effects on C-3 and C-4 are compared with carbon charge densities (qr).