Shizuko Ogawa

Nuclear Quadrupole Resonances in Arsenic and Antimony Trihalides and Sulphur Molecular Addition Compounds

Nuclear quadrupole resonances of I, Br, Cl, As and Sb isotopes in solids AsCl 3 , SbCl 3 , SbBr 3 , AsI 3 , SbI 3 , AsI 3 ·3S 8 , SbI 3 ·3S 8 , SnI 4 , SnI 4 ·2S 8 and SnI 4 ·4S 8 have been measured systematically. The newly obtained coupling constants e Q q and asymmetry parameters η of the I 127 resonances at 77°K are as follows: e Q q =1383.03, 1402.68 Mc: η= 0.002, 0.039 in SnI 4 ·2S 8 , e Q q =1364.3, 1368.3, 1405.0 Mc and η=0.00, 0.00, 0.03 in SnI 4 ·4S 8 . In SnI 4 ·4S 8 an additional line was observed at 219.04 Mc corresponding to the first resonance. The second resonance of SbI 3 was at 254.637 Mc with e Q q =895.83 Mc and η=0.565. Resonance frequencies of As 75 in AsI 3 and AsI 3 ·3S 8 at 77°K were 29.338 and 49.501 Mc, respectively. The first resonance of Sb 121 in SbI 3 was 25.406 Mc at 77°K and the corresponding resonance in SbI 3 ·3S 8 was 37.461 Mc at 297°K. SbBr 3 showed two crystal forms which gave Sb 121 coupling constants of 319.920 and 316.02 Mc and asymmetry parameters of 0.082 and 0....

Effects of Impurities on Nuclear Quadrupole Resonance in p-Dichlorobenzene

The resonance of Cl 35 in α phase p -dichlorobenzene containing various impurities was studied. The used impurities were p -BrφCl, p -Br 2 φ, p -I 2 φ, p -OHφCl, p -CH 3 φCl, p -NH 2 φCl, p -NO 2 φCl, p -NO 2 φCH 3 and p -(CH 3 ) 2 φ. The characteristic number which represents the number of resonant nuclei which is affected by an impurity molecule was measured. This characteristic number depends on the volume difference of the resonant and impurity molecules and independent on the difference in dipole moment. The results of the theoretical discussions supported the experiment. The height, width, shape and the integrated intensity of the resonance line were also measured. The integrated intensity was almost constant in the range of small concentration of impurity and then decreased.

Nuclear Quadrupole Resonances in Arsenic Tribromide and Arsenic Tri-iodide

The pure quadrupole spectra of As 75 , Br 79 and Br 81 in AsBr 3 , and of I 127 in AsI 3 have been studied by the method of superregenerative detection. The observed resonance frequencies yielded the following couplings: 127 Mc, 415 Mc and 1328 Mc for As 75 , Br 79 and I 127 respectively. The spectrum of bromine in arsenic tribromide was a triplet. Above 90°C, the iodine in arsenic tri-iodide also showed a triplet, whereas below that temperature it had a single line. The asymmetry parameter on iodine was determined from the resonance frequencies. The result was 18.4% at the liquid air temperature and 14.5% at the room temperature. The low couplings and the high asymmetry of iodine in arsenic tri-iodide were interpreted by the mechanism of resonance switching of the bond.

On the Piezoelectric Lines at Sub-microwave Frequencies

Piezoelectric absorption lines which had been found in the experiment of nuclear quadrupole resonance were studied in the frequency range between 3 Mc and 700 Mc. These lines were observed not only in powder, but also in single crystals. The present experiment showed that they were neither due to resonant vibrations of individual crystals in powder nor due to harmonics of the natural vibration of a single crystal. The absorption was dependent on imperfection of crystal and related to very narrow region in a crystal. The following mechanism was suggested: There are regions where the velocity of the elastic wave is smaller than the outside. Then vibrations are confined within the region because of total reflection at the boundary.

Nuclear Magnetic Resonance of Fe 57 in Various Ferrimagnetic Oxides

Enhanced nuclear magnetic resonance of Fe 57 in yttrium iron garnet, nine substituted iron garnets, magnetite and hematite were observed. In garnets two resonances for two positions of Fe 3+ were measured. Resonance frequencies in rare earth substituted iron garnets do not so much differ from the resonance frequencies of Fe 57 in yttrium iron garnet. If one compares relatively accurate resonance frequencies observed in various garnets, it is clearly seen that the effective magnetic field at the nucleus is proportionally increased with their crystal lattice parameters. The fractional variation of this field over all garnets is within four percents on both sites. The resonance of Fe 57 in magnetite is also enhanced by domain wall excitation. Two resonance frequencies corresponding to octahedral and tetrahedral sites were observed at room temperature. Below the transition temperature only one broad resonance was confirmed. A resonance of Fe 57 corresponding for Fe 3+ in hematite was observed on sample contai...Enhanced nuclear magnetic resonance of Fe/sup 57/ in yttrium iron garnet, substituted iron garnets, magnetite, and hematite were observed. In garnets, two resonances for two positions of Fe/sup 3+/ were measured. Resonance frequencies in rare-earth-substituted iron garnets differ little from the resonance frequencies of Fe/sup 57/ in yttrium iron garnet. Comparing relatively accurate resonance frequencies observed in various garnets, it is seen that the effective magnetic field at the nucleus is proportionally increased with the crystal lattice parameters. The fractional variation of this field over all garnets is within 4% on both sites. The resonance of Fe/sup 57/ in magnetite is also enhanced by domain-wall excitation. Two resonance frequencies corresponding to octahedral and tetrahedral sites were observed at room temperature. Below the transition temperature, only one broad resonance was confirmed. A resonance of Fe/sup 57/ corresponding for Fe/sup 3+/ in hematite was observed in a sample containing a small amount of magnetite.

Zeeman Quadrupole Spectra in p-dichlorobenzene and p-chlorobenzoic Acid

Zeeman effects of nuclear quadrupole resonance of p -dichlorobenzene and p -chlorobenzoic acid were studied. For p -chlorobenzoic acid only one C-C1 bond direction was observed. The molecular orientation against the crystal c -axis was obtained by the x -ray measurement. The asymmetry parameter was determined from the Zeeman effect to be 8%. For p -dichlorobenzene, the molecular orientation of the α phase to the β phase was studied. In most crystals examined the orientation in two phases is defined respectivey. However, there is no relation in two phases. The orientation may be restricted by dislocations which exist previously in single crystal. The obtained value of the asymmetry parameter is 6% which is smaller than Deans.

Nuclear Quadrupole Resonance of Antimony Isotopes in Solids

Measurements of nuclear quadrupole resonances of antimony isotopes in solids have been made at a relative accuracy of about one part in 10 6 . Detectors are superregenerative oscillators. Relative accuracy was achieved by measurement of two or three resonance frequencies in a very short time. For antimony trichloride the results were almost in agreement with Wangs data, but the resonant frequency ν 3 of the Sb 123 isotope, was higher about 2.5 kc. This implies that the cedecipole coupling constant might not have an order of magnitude which leads to a definitely measurable amount. In antimony oxide the simultaneous measurement was more easy, since it has a small asymmetry parameter. In this case, the deviation of resonance frequencies from a multiple relation is very small. These results are discussed in terms of cedecipole interaction and thermal vibration.

Proton Magnetic Resonance Absorption in Cetyl Alcohol

The line shape of the proton absorption in cetyl alcohol was studied with an autodyne receiver between room temperature and the melting point. The second moment was calculated from recorded derivative curves. The obtained second moment had a hysteresis effect. When the temperature was raised from room temperature, the second moment was almost constant of about 18.5 gauss 2 and it decreased abruptly to the value of 8 gauss 2 near the melting point. When the temperature was lowered from the melting point the second moment kept a small value till the transition point and then increased. The large second moment seems to be arisen from the monoclinic state and the small second moment from the hexagonal state. It was observed that the resonance line had a fine structure at its center.

Nuclear Magnetic Resonance of Fe57 in Lithium Ferrite and Magnetite

Nuclear magnetic resonance of Fe57 in lithium ferrite a frequency modulated spectrometer operated at a low power level. Second derivative of absorption versus frequency exhibited two strong lines and two weak lines. A sample quenched from high temperature exhibited resonances although the intensity was decreased. The x-ray diffraction of this sample showed weak superstructure lines which indicates a residual ordering. (W.D.M.)

Structure of Nuclear Quadrupole Resonance Line I. Solid Iodine

Broad resonance lines of Br 79 and Br 81 in a single crystal of bromine have been studied. If the theory of indirect spin-spin coupling is applied, ten components are expected for each lines even when asymmetry of the field gradient tensor is neglected. The observed derivative curves of the lines could not be resolved into more than three lines. Provided that the each components have a finite line width a rough agreement was obtained with the interaction constant of 3 kc. This value is resonable if the s -character of Br–Br bond is 18%. The ratio between overall line width of Br 79 and Br 81 accorded approximately with the ratio of the square of nuclear magnetic moment.