Showing papers in "Journal of Magnetic Resonance in 1973"

TL;DR: In this article, the authors describe methods to improve the resolution of a complex NMR spectrum by subtracting a broadened spectrum from the original one, which is brought about either by multiplying a transient response by an exponentially decaying function or by introducing a paramagnetic ion.

TL;DR: In this article, the causality principle on the relations between absorption and dispersion mode signals obtained in a repetitive pulse-fourier experiment is investigated with particular emphasis on the distribution of information between the two signals.

TL;DR: In this article, the longitudinal relaxation times of two-tryptophan protons were determined by using a new pulse sequence: apply a 90° pulse, spoil field homogeneity, wait for a delay time, τ, apply a90° sampling pulse.

TL;DR: In this paper, approximate solutions for the relaxation times T 1 and T 2 in chemically exchanging systems are derived from exact solutions without the usual assumptions that the system is dilute and that the relaxation time of the dilute species is much faster than that of the bulk species.

TL;DR: In this article, the Fourier transform of the spin echo using the pulsed gradient, spin echo technique was used to determine the self-diffusion coefficient of each component in a multicomponent system.

TL;DR: In this article, the eigenfield technique can be applied to both static and relaxing systems, but this contribution treats only stationary states, and some of its properties are discussed in detail.

TL;DR: In this paper, the effects of field-frequency instability and diffusion combined with external field gradients are discussed and methods for avoiding several of these errors are described and applied to the measurement of T2 for degassed benzene.

TL;DR: In this article, high-resolution proton undecoupled 13 C NMR spectra were obtained for pyridine and 2-bromopyridine using the 13 C isotope in natural abundance.

TL;DR: In this article, the authors analyzed the effect of cross-relaxation on the recovery of the longitudinal magnetization after a perturbation on a simple exponential curve described by a single time constant T1.

TL;DR: In this paper, an equation for NMR motional narrowing in solids based on the concept of two possible states for each ion: excited and nonexcited, was proposed, and the results provided a guideline for determining the nature of the motion (long-range or short-range) causing narrowing of the NMR line.

TL;DR: In this article, a detailed analysis of the resonance spectra of high concentrations of spin-labeled phospholipids incorporated into artificial and natural membranes is given, at high temperatures (>40°C) the spectra are analyzed in terms of spin exchange interactions.

TL;DR: In this paper, the transverse and longitudinal nuclear magnetizations for an internally rotating methyl group attached to a symmetric top molecule have been calculated; cross-correlation between the motion of two of the methyl protons and motion of the third has been taken into account, by extending an existing treatment by Hubbard to a range of rotational correlation times which are greater than or equal to the reciprocal nuclear Larmor frequency.

TL;DR: In this article, the effect on transverse nuclear spin relaxation of diffusion of molecules through magnetic field gradients arising from heterogeneity of the magnetic susceptibility of the system are discussed Similarities of these effects with the effects of spatially restricted diffusion in the presence of applied field-gradients and the motional narrowing of NMR lines are pointed out An expression is deduced for the contribution of diffusion through internal inhomogeneous fields to the attenuation of a spin echo.

TL;DR: In this article, the influence of vibrational motion on structural parameters is discussed, and the transformations from the observed effective NMR structures to average structures are compared with corresponding ones from electron diffraction or from optical or microwave spectroscopy.

TL;DR: In this article, the splitting pattern observed for the 13 C NMR signals in the 1 H-undecoupled spectra of symmetrically ortho-disubstituted benzenes differs characteristically for carbons in the position α and β to the substituted carbons, thus, giving rise to typical fingerprints.

TL;DR: In this article, the 13C nuclear spin-lattice relaxation times for ring and methyl carbons in liquid toluene were studied from −95°C to +60°C at frequencies of 14 and 61 MHz.

TL;DR: In this article, the influence of paramagnetic impurities on the line shape is analyzed, in detail, in the special case of spherical samples of spins 1 2 forming a simple cubic lattice.

TL;DR: The pure quadrupole resonance of 14 N has been measured in several compounds with nitrogen in a tetrahedrally bonded environment in this article, and the results are in good agreement with those predicted by a simple theoretical model.

TL;DR: The 14N pure quadrupole resonance spectrum for the ammonium group has been measured for the following amino acids in the solid state: l -cystine, l-cysteine, monoclinic and orthorhombic l -histidine, l -phenylalanine, and l -tyrosine as discussed by the authors.

TL;DR: In this article, the influence of an asymmetric local environment on NMR relaxation times and second moments was investigated by considering reorientational jumps between minima in a threefold potential where two of the minima have equal depth and the third has higher or lower potential energy.

TL;DR: In this article, the N + (CH 3 ) 3 groups of a sonicated dispersion of egg yolk lecithin in D 2 O have been recorded at 250 MHz under high resolution and slow sweep rate conditions.

TL;DR: In this paper, the experimental carbon-13 chemical shifts of acetylene, dimethyl acetylene and allene are reported and compared with existing values for methane, ethane, ethylene, methylacetylene, and benzene.

TL;DR: In this article, a variety of multipulse and Fourier transform NMR experiments have been simulated using a computer program based on the Bloch equations, which can calculate the effect of any sequence of pulses and delays on the magnetization vector.

TL;DR: In this article, the parameters in the spin Hamiltonian of isolated exchange-coupled paramagnetic ion pairs are derived through the application of the Wigner-Eckart theorem.