[en] The separation of rubidium isotopes (⁸⁵Rb and ⁸⁷Rb) was carried out at several temperatures by means of constant current electromigration in which a cation-exchange membrane of H-form was used as an electrophoretic supporting medium. A membrane strip was placed in a migration apparatus. A constant direct current was passed through the strip to move rubidium ions towards the cathode with a constant migration velocity. The diffusion coefficient of rabidium ion in the cation-exchange membrane was evaluated from Nernst-Einstein's equation; its values were 2.4 x 10^-6, 3.5 x 10^-6, 4.9 x 10^-6, and 6.9 x 10^-6 cm²/s, at 5, 25, 50, and 70 ⁰C, respectively. When the migration distance of the boundary reached 20 cm, the supply of the direct current was discontinued and the membrane strip was taken out of the apparatus and cut into fractions starting from the frontal end of the Rb-zone at a regular interval of 2.5 mm. For each fraction, the rubidium content and rubidium isotope ratio (⁸⁵Rb/⁸⁷Rb) were determined. The results of the isotopic analysis showed that the lighter isotope ⁸⁵Rb was enriched in the frontal part of the zone. Epsilon sub(v), the relative difference in migration velocity between ⁸⁵Rb and ⁸⁷Rb ions, was determined to be 0.77 x 10^-3, 0.85 x 10^-3, 1.11 x 10^-3, and 1.36 x 10^-3, at 5, 25, 50, and 70 ⁰C, respectively. A theoretical equation for chromatographic separation of isotopes was applied to the Rb isotope enriched zone. The present Rb-isotopic fractionation plofiles were found to obey the theory quite closely except for the one at 70 ⁰C. (Nogami, K.)

[en] Infrared spectra of LiOH and Li₂CO₃ suspended on KBr discs were measured over the concentration range 20 μg/100 mg KBr to 600 μg/100 mg KBr. The absorbance of a selected infrared band of each sample was carefully determined. The empirical equation, which expresses a correlation between the absorbance and the concentration, was given for each lithium compound. The feasibility of independent and direct determination of the LiOH and Li₂CO₃ content in Li₂O was shown, and the spectroscopic technique was applied to a typical Li₂O sample. It was shown that the detection limit of the analysis was improved by low-temperature measurements of the infrared spectra. (orig.)

[en] The deuterium spin-lattice relaxation time, T₁, of H₂O/D₂O mixtures is measured at 298.2 K. The relaxation rate, T₁^-1, is found to increase with increasing deuterium atom fraction, n, the plot of T₁^-1 vs. n exhibiting a small depature from linearity. A general equation T₁^-1 (n) for the H₂O/D₂O system is formulated. The temperature dependence of T₁ is investigated in the temperature range 278.2 K to 298.2 K for n=6.8x10^-3, 6.8x10^-2, 0.244, 0.500, and 0.997. On the assumption that the electric field gradient parameters (e² q Q/h and delta) are independent of n and temperature, an effective correlation time, tausub(c,eff,) is derived from the T₁ data. Relatively large isotope effects on tausub(c,eff) are found; possible reasons for the existence of such isotope effects are discussed in terms of a simple Debye model. The mean activation enthalpy (Δ sup(not equal) H) and entropy (Δ sup(not equal) S) for the relaxation process within the temperature range studied are derived on the basos of Eyring's absolute rate theory and the temperature dependence of tausub(c,eff). Both activation parameters are found to increase linearly with n: Δ sup(not equal) H/kJ mol^-1=18.2+2.46 n, Δ sup(not equal) S/JK^-1 mol^-1=37.5+6.77 n. (orig.)