Nobufusa Saito

The isotope effects in the isotope exchange equilibria of lithium in the amalgam-solution system

Abstract The elementary separation factors for lithium isotopes in the isotope-exchange equilibria between the amalgam and the organic solution have been measured at several temperatures between −15 and 85°C. DMSO, DMA and DEF were employed as the organic solvents for lithium salts. The separation factors with these systems have been found to be larger than those reported previously with other chemical exchange systems. Lithium-6 has been enriched in the amalgam phase in all the systems studied. The separation factors vary from 1·085 to 1·028, decreasing with an increase in the temperature. By plotting the logarithm of the separation factors vs the reciprocal of the square of the temperature, a nearly linear correlation was obtained. In the systems employing DMSO, the separation factors decrease in the following order: α CH 3 COOLi ≈ α LiI ≈ α LiBr > α LiCl > α LiNO 3 . The kind of the organic solvent has been found to affect the separation factor. The separation factors for the DMA or the DEF solution systems are larger than those for the DMSO-solution systems over the range of temperature investigated. The large separation factors obtained in these experiments indicate that the present isotope-exchange process may be suitable for the enrichment of lithium isotopes.

Mössbauer emission spectra of 119Sn after the EC decay of 119Sb in metals, oxides, and chalcogenides of antimony and tellurium

Mossbauer emission spectra of 119Sn have been measured in metals, oxides, and chalcogenides of antimony and tellurium labeled with 119Sb or 119mTe. Sources of 119Sb and 119mTe metals gave an emission line in the Sn(0) region. In the emission spectra of 119Sb2O3 the species attributable to the Sn(II) state were dominant, while only the Sn(IV) species was found in the 119mTeO2 samples. The 119Sb2S3 and 119Sb2Se3 gave two emission lines attributable to the Sn(II) and Sn(IV) states. The 119Sb2Te3 showed only an emission line in the Sn(II) region. These observations were discussed in terms of the aftereffect of the EC (electron capture) decays and the properties of the matrices.

Hot-atom chemistry of cobalt complexes—I: Hot-atom chemistry of nitroammine cobalt (III) complexes

Abstract Nine kinds of nitroamminecobalt (III) complex compounds were irradiated with slow neutrons for 1,5 or 30 hours in JRR-1 reactor. After various storage times the 60Co-labelled recoil species in the irradiated compounds were separated by means of procedures involving paper electrophoresis, paper chromatography, ion exchange, or precipitation. It was found that the labelled species were composed of the target complex, Co2+ ion and the complexes produced through incorporation of outer ions (or molecules) as ligands. The results can be explained by assuming that an electrostatic interaction plays an important role in recoil reactions. The effects of irradiation and storage time on the distribution of recoil species were also investigated.

A Mössbauer spectroscopic study of the electronic states of tetragonal iron(II) pyridine complexes

Abstract The Mossbauer spectra of FeL 4 Cl 2 (L = pyridine, 4-methylpyridine, 3-acetylpyridine) and Fe L 2 Cl 2 (L = pyridine, 4-acetylpyridine, 4-chloropyridine, 3-chloropyridine) were measured between 4·2 and 290°K. The magnitudes of the quadrupole splittings ( ΔE Q ) of FeL 4 Cl 2 are much larger than those of FeL 2 Cl 2 , probably because of the different orbital ground-states: d xy for FeL 4 Cl 2 and, most likely, d xz and d yz for FeL 2 Cl 2 . The energy separation, δt 2 g , was estimated from the temperature dependence of ΔE Q . No effect on the isomer shift of a substituent at the 3- or 4-position of pyridine is observed in either FeL 4 Cl 2 or FeL 2 Cl 2 .

Chemical Effects of Nuclear Recoil following (n,γ) Reactions in Bromates

THE chemical distribution of radioactive recoil atoms arising from nuclear reactions in solid state is the consequence of a series of complicated processes and depends on many factors such as the nature of nuclear reaction, the chemical environment of the recoiling atom and the conditions of experiment. Investigation of the effects of these factors on the chemical fate of recoil atoms is required to clarify the mechanism of the whole recoil process. The present communication describes the recoil effects of 79Br(n,γ)80mBr and 81Br(n,γ)82Br reactions in a variety of bromates. The isotope effect reported by Jach and Harbottle for alkali bromates1 was also found for bromates of other metals. The retention of radioactive bromine atoms as bromate was found to be affected by the basicity of the cation.

Radiation Decomposition of Aqueous Azide Solution

When an aqueous solution of azide ion is irradiated with γ rays of 60Co, nitrogen gas, hydroxyl ions, and ammonia are produced. Hydrogen peroxide is not formed while hydrogen is produced equal to GH2w. The reaction mechanism may be well explained by assuming the oxidation of azide ion by the hydroxyl radical and the reduction by the hydrogen atom. Applying the expanding‐spur theory of Ganguly and Magee to the system, all the features of the radiolysis are well understood. The number of water molecules initially decomposed was determined as 5.5. The rate constant of the reaction, OH+N3—=OH—+N3, was calculated to be 8×1010 liter mol—1 sec—1.

CHEMICAL EFFECTS OF NEUTRON-INDUCED NUCLEAR REACTIONS IN HALATES AND RELATED COMPOUNDS. II. (n,2n) REACTION IN BROMATES.

Summary The recoil effects of the (n, 2n) reaction were studied in bromates. In sodium bromate the distribution of radioactive bromine atoms in various chemical forms was almost the same for the 79Br(n, 2n) 78Br and 79Br (n, γ)80Br reactions. A similar relationship between the retention and the nature of cations was found for the (n, 2n) and (n, γ) reactions in several bromates.

The Isotope Effect in the Electromigration of Sodium-Ion in Fused Sodium Nitrate

The isotope effect of sodium-ion in countercurrent electromigration (Klemms method) has been investigated for a system of fused sodium nitrate labelled with the radioactive nuclide 22Na. Two runs were made (Experiments A and B, respectively). In Experiment A, the fused salt chain, Al(cathode)-NaNO3-Pt(anode) was electrolyzed for 20 hr at 340 ?? with a current density of 1.3 A/cm2 in the separating tube. In Experiment B, electrolysis was carried out for 67 hr at 380 ?? with a current density of 1.5 A/cm2 in the separating tube. After electromigration, a change was observed in the specific activity of sodium in the separating tube. The elementary process separation factor, defined as the ratio of the mobilities of the isotopic ions, i.e., VNa-22/VNa-23, was calculated to be 1.0023 for Experiment A and 1.0017 for B. The mass effect for sodium ion in fused sodium nitrate was calculated to be -0.045±0.006 (standard deviation).

Photolysis of Aqueous Azide Solutions

Azide ion solutions containing mercuric chloride were photolyzed with ultraviolet light from a mercuric arc. The products were nitrogen and mercurous azide, both of which were produced by a chain mechanism. Assumptions that the reaction is initiated by photochemical charge transfer from an azide ion to water and that the chain carriers are the lowest triplet state nitrogen molecule and the excited azide radical can account for the reaction of azide ion plus mercuric chloride system.Based on the same assumption, the photolysis of pure azide ion and hydrogen azide solutions have been successfully reviewed.

Enrichment of 7Li by countercurrent electromigration of molten lithium nitrate

Abstract Lithium-7 has been enriched from the natural abundance 92·58 to 99·94% (maximum) by countercurrent electromigration of molten lithium nitrate. In order to realize high enrichment in a short time, fine packing material of quartz (≯ 150 mesh) has been used. Both cylindrical and pseudotruncated cone shaped separation tubes have been used and the latter are found to be more efficient for rapid enrichment. In both cases the distribution of the salt at a stationary state can be expressed approximately in terms of a truncated cone shaped distribution. The most favorable conditions for high enrichment are discussed regarding the temperature, the grain size of the packing material and so forth.