Further neighbour interactions in the quasi b.c.c. Heisenberg ferromagnets M2 Cu X4 · 2H2 O (M = NH4, K,Rb or Cs; X = Cl or Br)

The Curie-Weiss constant θ of the quasi b.c.c., $\text{S =}\text{1}\text{2}$, Heisenberg ferromagnets, (NH₄)₂ Cu Br₄ · 2H₂ O and Rb₂ Cu Br₄ · 2H₂ O, have been derived from measurements of the susceptibility in the paramagnetic region (4.2 < T < 100 K) and of the high-field magnetization curves at $\text{T = 4.2}\text{K}\text{(}\text{T}\text{T}{}_{\mathrm{c}}\text{? 2.3)}$. The $\text{T}{}_{\mathrm{c}}\text{θ}$ values obtained point to the presence of further neighbour interactions considerably stronger than previously assumed. The effective number of equivalently interacting magnetic neighbours is estimated to be at least seventeen.     

Crystallization kinetics of amorphous FeB alloys by dta

The crystallization kinetics of amorphous FeB alloys was investigated by means of differential thermal analysis. The activation energy for the crystallization of amorphous FeB alloys was estimated. The concentration dependence of the activation energy, exhibiting a maximum at about 16 at.% B, has similarity to other physical properties.     

Oxygenation of p-nitrophenylhydrazones with Co(II)-schiff base complexes

$\text{p}$-Nitrophenylhydrazones, unsusceptible to autoxidation, are readily oxygenated in the presence of a five-coordinate cobalt(II)-Schiff base complex, Co(II)(MeOSalen) (Py) leading to quantitative formation of novel 1-($\text{p}$-nitrophenylazo)-1-peroxy Co(III) complexes 2, which were isolated as crystals. A plausible mechanism involving hydrogen abstraction by Co(III)(O₂^?.) from the substrate followed by formation of a substrate anion Co(III) complex intermediate is proposed.     

Measurement of flow-birefringence using a circularly polarized laser beam

A method of measuring flow-birefringence is reported. In this method, a circularly polarized light wave is transmitted through the flow-birefringent medium. The transmitted elliptically polarized wave is compensated by a Babinet-Soleil plate to convert it back into a circularly polarized wave. The state of circular polarization is confirmed using the rotating-analyser method. Measurements can be carried out with a sample having a fixed azimuth. The minimum detectable optical retardation angle was 5 × 10^-3 degree. This corresponds to a birefringence of Δn = 1 × 10^-10, when the optical path length of the sample cell is 100 mm.     

Energies,oscillator strengths,and phonon side bands for an exciton in polar semiconductors

Within the Wannier exciton model for polar semiconductors, energies, oscillator strengths, and phonon side bands are calculated for the exciton ground- as well as the excited-states. Numerical results for CuCl and CuBr have been found to agree quite well with experiments. In particular, the one phonon side band for the 2s-state in CuCl is shown to be as strong as the zero phonon line.     

Stable isobenzofuran endoperoxide and its use for oxidation of olefins ans aromatic compounds

1,3-Di-tert-butylisobenzofuran reacts with singlet oxygen with rate constant of 2.8 x 10⁹ M^?1 sec^?1 to give stable endoperoxide $\text{4}$. Thermolysis of the endopepoxide ($\text{4}$) in the ppesence of norbornene and naphthalene gave the corrpesponding epoxide and naphthols, respectively. Addition of Pd(OAc)₂ improved the yield of naphtols considepably.     

Experiments on the propagation of lower hybrid waves in a toroidal plasma

The propagation of the lower hybrid waves is investigated in a toroidal afterglow plasma by using a pair of the half-turned strip lines. It is confirmed that experimental results of propagation in a toroidal plasma well agree with calculated ones from the cold plasma theory.