Yukio Yamagata

Nuclear Magnetic Resonance Experiments on Ammonium Halides, II Halogen Nuclear Magnetic Resonance

The chemical shift, spin-lattice relaxation time, and intensity of nuclear magnetic resonance line were measured for ammonium chloride, bromide and iodide in various phases. It was found that the reorientational motion of ammonium ion is the origin of time dependent interaction necessary to relax the nuclear spin orientation. The deformation of the halogen ion core, arising from the interaction with alkali ions, is discussed in connection with the chemical shift and spin-lattice relaxation time. In ordered phase, T 1 in the chloride became much longer than that in phase II, while in the bromide electric quadrupole splitting of NMR line appeared, and the ordering parameter was estimated. From the result of the intensity measurements, the effect of crystal imperfection upon NMR is discussed.

Chemical Shift, Relaxation Time, and Electric Quadrupole Coupling in Alkali Halides

Chemical shift and spin lattice relaxation times are measured for Cl 35 in all the alkali chloride crystals and for Br 81 and I 127 in some of the halides. These measured values cannot be explained by using Kondo-Yamashitas theory alone which takes into account the effect of overlap between the central ion and the nearest neighbors. For the chemical shift, it seems that the overlap with the second nearest neighbors is an essential cause of the discrepancy and that the covalent and the electrostatic effects are rather small. If these conclusions are admitted, there must be a large chemical shift (about -2∼-3×10 -4 ) of chlorine ion in aqueous solution relative to the free chlorine ion. A model combining the electrostatic and the overlap effect is proposed to explain reasonably the relaxation times in the crystals. The electric quadrupole coupling in free molecules of alkali halides is also discussed from the present viewpoint. The combination of the electrostatic and the overlap effects seems to give a re...

Nuclear Magnetic Resonance Experiment on the Single Crystals of K2HgCl4·H2O and K2SnCl4·H2O. II, The resonance absorption due to four proton system and the revised determination of their crystal structures

The energy levels and the transition probabilities are calculated for four proton interaction. The result of calculation is applied to the case of the single crystals of K 2 HgCl 4 ·H 2 O and K 2 SnCl 4 ·H 2 O. Ten absorption lines are expected from the theoretical calculation, of which each five form a group. Since in general cases the separations between the lines belonging to one of these groups are small compared to the separation between these groups as a whole, the expected resonance figure roughly coincides with the case of two proton resonance. But the shapes of resonance peaks have further fine structures. The observed fine structures were analysed by the theoretical consideration, and it is shown that the agreement between the theory and the experiment is satisfactory, if we take the distance of main protons to be 1.607 A and the distance between the proton-proton lines for adjacent water molecules which are parallel with each other to be 3.60 A in the case of Hg-salt and 1.62 A and 3.90 A respe...

The Electric Quadrupole Splitting of the Nuclear Magnetic Resonance Lines of Sodium in a Single Crystal of Na2S2O3·5H2O

Splitting of the nuclear magnetic resonance lines of sodium due to the nuclear electric quadrupole interaction was measured in a single crystal of sodium thiosulphate pentahydrate. Since each molecule contains two sodium nuclei which have different electric quadrupole interactions, and there are two groups of molecules with different orientations in a unit cell, twelve lines were observed in general. The experimental results were compared with the theoretical calculation of Bersohn and the values of e 2 q Q , η and the directions of the principal axes of the field gradient tensor were determined for each nucleus. The values of e 2 q Q and η are 2.26 Mc/sec and 0.334, and 0.830 Me/sec and 0.41 respectively for two nuclei in the molecule.

Nuclear Magnetic Resonance Experiment on the Single Crystals of K2HgCl4·H2O and K2SnCl4·H2O. Part I

Proton magnetic resonances of water molecules in the single crystals of K 2 HgCl 4 ·H 2 O and K 2 SnCl 4 H 2 O were observed, and the distance and the direction of proton-proton line in each of water molecules in the unit cell were determined. The absorption lines are generally composed of four component lines, of which the separation varies with the direction of the externally applied magnetic field. These results are fairly well explained with the Pakes formula for two-proton system and by the fact that there are two different p-p directions in these crystals. The p-p distance in a water molecule determined in this experiment is 1.607 A, and the angles between the a -axis and p-p lines which lie on the plane parallel to the c -plane are ±21.4° for Hg-salt, and 1.62 A and ±39.5° respectively for Sn-salt. Each component line has further fine structures when the external field is applied to some particular directions. This cannot be explained by the assumption of two-spin system only, but understood by in...

Nuclear Magnetic Resonance Experiments of I 127 in KI

A series of experimental studies on nuclear magnetic resonance of alkali halides was made. The temperature dependence of the spin-lattice relaxation time and chemical shift of iodine nuclear magnetic resonance in KI crystals are reported. (auth)