Kineo Tsukada

Zeeman Splitting of Nuclear Quadrupole Resonance in Paradibromobenzene

Zeeman patterns of the nuclear quadrupole resonance line of Br 79 were studied with a single crystal of paradibromobenzene. The crystal contains two classes of molecules with equal positive and negative inclinations against the crystallographic b -axis. Changing the orientation of magnetic field in the plane perpendicular to the b -axis, the Zeeman patterns were measured. The asymmetry parameter of the coupling, η, was determined from the pattern at the magnetic field perpendicular to all carbon-brormine bonds. The result was η=0.12±0.01. The coupling constant, e Q q , was measured as 535.19 Mc at 14°C. If the asymmetry parameter is completely due to the resonance of a double bond structure in the carbon-bromine bond, the observed value gives 4.5 per cent double bond character.

Zeeman Splitting of Nuclear Quadrupole Resonance Line of Bromine

With a single crystal of about 35 g, which was prepared by the method of the pointed-bottom crucible. Zeeman patterns of the pure quadrupole spectrum of bromine were studied. The observations were carried out in the following orientations of the magnetic fields: (1) parallel to the b axis of the crystal, (2) parallel to the c axis and (3) about 43° from the b axis in the a plane. The pattern at the b axis, where the magnetic field was perpendicular to all molecular bonds, consisted of four lines. This indicated the existence of asymmetry in the field gradient tensor. The asymmetry parameter η was determined as 20 percent. This large value was discussed from the standpoint of resonance switching of auxiliary bonds.

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.

Microwave Spectra of CHBr3 in the Region from 11 to 12.5 Centimeters

The spectrum of rotational transition J=0→1 of bromoform has been estimated to lie in a 10‐cm region. In this region, however, the spectroscopy has not yet been studied because of small absorption. Some of the present authors (S. K., K. T., and S. H.) had examined its detectability by the preliminary experiment with a cavity spectrometer. In the present paper more precise measurement using an absorption cell of 9 meters in length and its analysis by means of the theory proposed by some of the authors (M. M. and T. I.) are described. Thirty‐two lines due to the hyperfine structure of the rotational transition were measured in the region from 2400 to 2660 mc/sec. The width of line was smaller than 2 mc/sec at 3 mmHg. The theory agreed well with the experiment. The value of the moment of inertia obtained here agrees with the result of electron diffraction, and this moment seems not to change appreciably by a low frequency deformation vibration. The quadrupole coupling constant of Br nucleus is nearly equal to that of CH3Br molecule.

Statistical Analysis of Fast Neutron Total Cross Sections of Silicon, Phosphor, Sulfur, and Chlorine

The neutron total cross sections of silicon, phosphor, sulfur, and chlorine in the energy range from 3 to 5 MeV have been measured with an energy resolution of 20 to 50 keV, and the variations of the cross sections with energy have been analyzed statistically under the assumption that the variations arise from the fluctuation of the neutron widths and spacings of the resonances which are covered by the energy resolution. The average spacings D , which are obtained by the present analysis, are 1.3 0.13, 0.54, and 0.04 keV for silicon phosphor, sulfur, and chlorine, respectively. These values agree well with those calculated by Camerons semi-empirical formula. The neutron strength functions \({\langle}{\varGamma_{n}}^{0}{\rangle}/D\), which are obtaind also by the present analysis, are 2.9, 3.9, 3.8, and 4.7×10 -4 for the respective elements, and are consistent with those obtained by the low-energy-neutron experiments. The correlation between the fluctuation of the total cross sections and the energy are o...

Inelastic Scattering of Neutrons by the Time-of-Flight Method

Neutrons scattered by Ti, Fe, Zn and Se have been observed by the time-of-flight technique in the energy range of 3.4 to 4.6 MeV. The inelastic scattering cross sections for the excitations of the 1st, 2nd and 3rd levels of these elements except Se, were obtained. The excitation functions of these levels were compared with those calculated with a formula which was made by modifying Hauser-Feshbachs formula so as to be used without detailed knowledge about the levels of high excitation. Agreement was fairly well except for the case of the 2nd and 3rd levels of Zn, where calculated values were about twice as large as experimental values. Thus it has been concluded that the compound-formation process is considered to predominate over the direct process in these energy and mass regions.

Total Cross Sections of Carbon, Oxygen, Fluorine and Thorium for Fast Neutrons

The neutron total cross sections of carbon, oxygen, fluorine and thorium have been measured in the energy range of 3.3 to 5.0 MeV. Measurements were made with a good-geometry arrangement and an energy resolution of about 20 keV, using a neutron detector which had a high efficiency and a good characteristic for gamma-ray discrimination. For carbon, oxygen and fluorine, several resonances in the cross sections were analyzed to give spin assignments. For thorium, a giant resonance was observed at 4.2±0.2 MeV.