Systematics of the nuclear spin polarization of12B in14N induced heavy ion reactions

Systematic study of polarization of projectile like fragment¹²B in¹⁴N induced reactions on light mass-number targets has been continued. A large positive polarization at small energy loss region was observed for an²⁷Al target at various reaction angles. Polarization is studied as a function of kinetic energy and reaction angle of¹²B in terms of a classical frictional force.Positive polarization is defined by where k_f and k_i are outgoing and incoming wave vectors, respectively.     

Neutron diffraction study on protonated and hydrated layered perovskite

A layered perovskite compound with Na⁺, D₃O⁺ ions (H₃O⁺) and D₂O molecules (H₂O) in the interlayer, D_xNa_1−xLaTiO₄·yD₂O, has been prepared by an ion-exchange/intercalation reaction with dilute DCl solution, using an n=1 Ruddlesden-Popper phase, NaLaTiO₄. Its structure has been analyzed in order to clarify the interlayer structure by Rietveld method, using powder neutron diffraction data. The structure analysis revealed that the layered structure changed from the space group P4/nmm-I4/mmm after the ion-exchange/intercalation reaction, and it induced the transformation of perovskite layers from staggered to an eclipsed configuration. The D₂O molecules and D₃O⁺ ions loaded in the interlayer statistically occupied the sites around a body center position of rectangular space surrounded by eight apical O atoms of TiO₆ octahedra in upper and lower layers.     

Fluorescence of the antharacenes following Tn → T1 excitation studied by a double excitation method

The fluorescence from the lowest excited singlet state following excitation of the lowest triplet state was observed for anthracene, 9-methylanthracene, and 9-phenylanthracene in ethanol by a newly devised double excitation method which is essentially the combination of flash and laser photolysis. The quantum yield of intersystem crossing from the excited triplet state, T_n(n ? 2), to the lowest excited singlet state was markedly increased by methyl- and phenyl-substitution at the meso-position.     

Epoxidation of styrenes with the peroxidase from the cultured cells of Nicotiana tabacum

An enzyme concerned with the epoxidation of styrenes was isolated from cultured cells of Nicotiana tabacum. The enzyme had peroxidase activity as well as epoxidation activity, and its amino acid sequence showed 89% homology in their 9 amino acid overlap with horseradish peroxidase. In the enzymatic reaction, hydrogen peroxide and p-cresol were necessary and molecular oxygen was the source of the oxygen atom of the epoxide. The enzymatic reaction using a spin trap reagent and monitoring of the reaction with ESR indicated that the epoxidation reaction of styrenes proceeded by a radical mechanism with peroxidase.     

Time component of the mirror beta decays of12B and12N

Beta-ray angular distributions from aligned¹²B and¹²N have been observed in order to study the meson-exchange effect in a nucleus. Alignment-correlation coefficients for¹²B and¹²N were determined to be _–=–(0.0174±0.0059)%/MeV and ₊=–(0.2774±0.0086)%/MeV, respectively. These values are fairly consistent with the previous values, while the reliability was greatly improved. From these coefficients, the nuclear parametery, i.e. the ratio of the time component of the axial vector currents of the Gamow-Teller matrix element, was determined to bey=4.13±0.15. The value is enhanced by 33% from that calculated by use of the impulse approximation, which clearly shows a considerable effect due to meson-exchange currents.     

Giant quadrupole moment andproton halo discovered in8B

The nuclear quadrupole moment of⁸B(I =2⁺,T _1/2=769 ms) has been determined by use of a modified -NMR detection as |Q(⁸B)|=68.3±2.1 mb, which is twice the prediction of the Cohen-Kurath shell model calculation. The anomalous quadrupole moment which is carried mainly by the protons in the nucleus, has been accounted for by the proton halo effect.     

Precise measurement of the magnetic moment of doubly closed shell + 1 nucleon nucleus17F(I π=5/2+,T 1/2=64.5 s)

Hyperfine interactions of -emitting¹⁷F implanted in single crystals of NaF and CaF₂ were studied. The nuclear magnetic moment of theI =5/2⁺ state was determined with improved precision to be |(¹⁷F;I =5/2⁺,T _1/2=64.5s)|=4.72130±0.00025 µ_N.     

Beta-NMR detection of beta-emitting fragment43Ti

NMR on the beta emitter⁴³Ti has been observed by use of the -NMR technique. From the observed NMR spectrum, the magnetic moment of⁴³Ti was determined to be || =0.85±0.02 µ_N. The value is significantly quenched from the single particle value –1.91 µ_N, which shows a strong effect resulting from meson-exchange currents andconfiguration mixing.