Yoshika Masuda

Nuclear Magnetic Resonance in α- and β-Manganese Metals

Nuclear magnetic resonance studies on Mn 55 in α- and β-Mn metals have been made by both the steady and the pulse methods. Nuclear spin-lattice relaxation time T 1 and spin-spin relaxation time T 2 were measured by the pulse method in the temperature range of 1.5°K to 77°K. The measured value of T 1 T of β-Mn keeps a constant value of 7 m sec °K through the temperature range measured. Using both the T 1 T value and the Knight shift, the origin of the effective magnetic field acting on a nucleus in a Mn metal was concerned. T 2 of 0.1 m sec. was observed to be temperature independent. Several nuclear spin-lattice relaxation mechanisms together with the origin of the effective magnetic field in the Mn metal are discussed. T 1 due to the dipole, quadrupole, and orbital interactions is calculated using free electron approximation in which the electronic wave function includes partly p - or d -character. It is shown that the orbital interaction is more effective than those due to the dipole or quadrupole inter...

Nuclear Magnetic Resonance in Molecular Chlorine Compounds

We have measured the chemical shifts, the transverse- and longitudinal-relaxation times of chlorine nuclear magnetic resonance of such liquid chlorine compounds as TiCl 4 , VOCl 3 , CrO 2 Cl 2 , and SiCl 4 , of which the quadrupole coupling constants were measured by Dehmelt by means of the pure quadrupole resonance experiment. Our results were considered in view of the correlation to quadrupole coupling constant. Line widths are nearly proportional to the square of the quadrupole coupling constant. The equality cf the transverse relaxation time T 2 and the longitudinal relaxation time T 1 has been verified experimentally in these compounds. Solomons method for the calculation of T 1 and T 2 was applied to a quadrupole relaxation. T 1 is exactly equal to T 2 in cases where quadrupole relaxation is essential, the molecular surroundings are isotropic, and further the extreme narrow conditions are well established. This result is identical to Wangsness and Blochs. Experimental T 1 values are about ten time...

Concentration Shift of Nuclear Magnetic Resonances in Some Concentrated Acids

Chemical shifts of nuclear magnetic resonances are caused when two nuclei of the same kind have different magnetic shieldings caused by their environments. When there are two species of molecules having a chemical shift between them and if they are exchanging their states very rapidly by chemical reaction, we cannot observe their nuclear magnetic resonances separately but we observe a single resonance at the position of the field averaged over the two states with a weight of their populations. We observed such resonances for N 14 , Cl 35 , Br 81 and I 127 in concentrated aqueous solutions of HNO 3 , HClO 4 , HCl, HBr and HI, respectively. In these cases, the chemically exchanging states are ions and undissociated molecules and from the measurements of the shifts we can get some knowledge of the concentrated acid solutions, such as the degrees of dissociation, the type of the undissociated molecule and so on. All the nuclei examined here have the quadrupole moments, and from the measured line width in HCl,...

Nuclear Magnetic Resonance Experiment on Metal Cadmium. II

The spin-lattice relaxation time, T/sub 1/ and the spin-spin relaxation time, T/sub 2/, of the resonance line in metal cadmium were measured by use of a nuclear magnetic resonance technique. The contribution of p-character in the conduction electron to the relaxation was estimated. The line width was measured at a temperature between the room temperature and 250 d C. It was shown that the exchange broadening between uniike spins underwent a motional narrowing. The inverse line width or spinspin relaxation time, T/sub 2/, was interpreted in terms of the lattice diffusion theory. These analyses yielded for the coefficient of self-diffusion D the value 0.05 cm/sup 2/sec exp (-17.6 kcal/ mol-RT). (auth)

NUCLEAR SPIN--LATTICE RELAXATION IN SUPERCONDUCTING MIXED STATE.

The nuclear spin-lattice relaxation time T 1 of V 51 in a type II superconductor V 3 Sn in the mixed state has been measured. In the case of T c (0)> T c ( H )>0.6 T c (0), abrupt decrease of T 1 appears at the critical temperature corresponding to the magnetic field in which T 1 was measured, T c ( H ), and then increases gradually. In this case of low magnetic field and high temperatures near T c (0), the temperature variation of T 1 shows the behavior predicted by a Bardeen-Cooper-Schrieffer (BCS) theory of superconductivity. In the case of T c ( H )<0.6 T c (0), just below T c ( H ) corresponding to that field, T 1 shows no minimum but increases monotonically. These behaviors in the case of high magnetic field and low temperatures can be understood quantitatively on the basis of the theory of gapless superconductivity.

Nuclear Magnetic Resonance and Specific Heat Measurements of Transition Metals and Alloys; Ti–V–Fe and Zr–Nb–Mo Systems

The nuclear spin-lattice relaxation times (T 1 ) of V 51 and Nb 93 in the body-centered cubic Ti-V-Fe and Zr-Nb-Mo alloy systems have been measured. The product of T 1 and temperature T, T 1 T is strongly dependent upon composition. These relaxation behaviours can be correlated to that of the low temperature specific heat. The Knight shifts of Nb 93 nuclear magnetic resonance in Zr-Nb-Mo alloy systems have also been measured. The composition dependence of Knight shift can be related to the relaxation result as well as to the results on low temperature specific heat and magnetic susceptibility. The electronic specific heat coefficient γ of Zr-Nb alloys has been measured for the sake of interpretation of the experimental behaviours of T 1 and Knight shift.

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 Relaxation in Antiferromagnetic α-Mn Metal near the Néel Temperature

Nuclear magnetic resonance studies on Mn 55 in α-Mn metal and Mn-Cr alloys which have an α-Mn phase in the temperature range around the Neel transition point, have been made by a pulse method. Nuclear spin-spin relaxation time T 2 has shown discontinuity at the Neel temperature, T N . The T 2 values are well proportional to ( T N - T ) 1/3 in antiferromagnetic state and to ( T - T N ) 2/8 in paramagnetic state. The measured values of T N in α-Mn metal, Mn- 1 at.% Cr, and Mn- 2 at.% Cr alloys determined by nuclear magnetic resonance method are 95.0±1.0°K, 81.6±1.0°K, and 72.3±0.5°K, respectively. Mn- 5 at.% Cr alloy did not show an antiferromagnetic behaviour even at 4.2°K. T N decreases with Cr content, but increases with Fe content. These results suggest that the rigid-band model is a good approximation for these metal alloy systems.