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[en] The interacting boson model of Arima, Iachello, and co-workers is applied to the even ruthenium isotopes, 96Ru∼116Ru. Excitation energies, electromagnetic transition strengths, quadrupole and magnetic dipole moments, and Δ(E2/M1) mixing ratios have been described systematically. Mixed symmetry states are investigated. It is seen that the properties of low-lying levels in these isotopes, for which the comparison between experiment and theory is possible, can be satisfactorily characterized by the Interacting Boson Model-2.
[en] The isotopic composition of Ru has been measured mass spectrometrically in an acid resistant residue of the Allende meteorite and in one magnetic and three non-magnetic portions of type-B inclusions, two from Allende and one from Leoville. Normalized to 96Ru/101Ru = 0.324851, all 98Ru/101Ru and 99Ru/101Ru ratios were found to be indistinguishable from the terrestrial values within 1.6 permil and 0.4 permil respectively. Thus, in the sampled reservoirs we find no evidence for different relative amounts of radiogenic 98Ru and 99Ru from the decay of now extinct 4.2 Myr-98Tc and 0.21 Myr-99Tc. 100Ru/101Ru and 104Ru/101Ru were found to deviate from the terrestrial norm by more than 2 σ (<= 0.6 permil) in one and two cases, respectively. Since terrestrial ratios were occasionally compromised by molecular interferences to an even larger extent, these overabundances cannot be unambiguously attributed to nonlinear isotope anomalies in the samples. The 102Ru/101Ru ratio is normal in two aliquants of the acid resistant Allende residue but higher than normal by up to 0.35 permil in all four inclusion samples. There is a possibility, although very remote, that these excesses are due to contamination by a 102Ru spike. A less conservative interpretation of the data and normalization to 104Ru/101Ru rather than to 96Ru/101Ru results in overabundances of the light p-process isotopes 96Ru and 98Ru in the non-magnetic portions of all three inclusions. (author)
[en] A technique has been devised to date Precambrian uranium ore samples by measuring the concentrations of 238U and of ruthenium isotopes that result from the spontaneous fission of 238U. The concentration of the latter depends on (1) the amount of 238U present, (2) the spontaneous fission decay rate, (3) the ruthenium fission yields for 238U, and (4) the duration of spontaneous fission, i.e., the age of the ore. Ruthenium in Precambrian ores has been identified as being from the natural abundance, the spontaneous fission of 238U, and the more variable neutron-induced fission of 235U. The contribution from ''common'' natural ruthenium is typically 1 ppB and is determined from the isotopes of mass 96, 98, and 100, which are not produced in fission. The ratio of isotopes of mass 99, 101, 102, and 104 for 238U spontaneous fission has been found to be significantly different from that ratio for 235U neutron-induced fission. Hence, the amount of ruthenium in an ore sample which results solely from 238U spontaneous fission can be determined. Several Precambrian uranium ore samples have been dated using this technique, and the ages compare favorably to values determined by other techniques. The component of ruthenium resulting from neutron-induced fission of 235U varied between about 5 and 50 percent of the amount from 238U spontaneous fission, and the component of common ruthenium was typically about 25 percent of the total ruthenium. This uranium--ruthenium technique should complement existing radiogenic dating techniques because it relies on a radiogenic product whose geochemistry is different from that of products or intermediates in the other decay sequences
[en] The physico-chemical behaviour of prepared binuclear oxygen-bridged nitratonitrosylruthenium, [RuO2(NO)2(NO3)]2O, was investigated by filter paper electrophoresis, paper chromatography, and infrared absorption spectra of a decomposition product in fresh water. The binuclear (Ru-O-Ru) nitrate complex in aquatic systems was electrophoretically fractionated into at least four 'anionic' species, one 'neutral' species and one 'cationic' species, with aging, and about 75% of the total Ru was present in the anionic fractions. It was found that about 90% of the total Ru in the solution was taken up in the fraction with Rsub(f) less than 0.2, corresponding to the anionic mononitro-, mononitrato- and probably the polynuclear species from paper chromatography. The proportions of Rsub(f) 0-0.2 and Rsub(f) 0.2-1.0 to total Ru were scarcely altered by increasing the aging time more than one day. On the basis of infrared spectra of decomposition product by aging the (Ru-O-Ru) nitrate, it was confirmed that two oxide anions, nitrosyl, nitro, nitrato groups and water molecule are all coordinated to Ru metal, assuming [RuO2(NO)(NO2)(NO3)(H2O)]- as one of the possible chemical forms of the anionic species. RuNO-nitrato, RuNO-nitro and (Ru-O-Ru) nitrate complexes were entirely adsorbed by the addition of 500-700 ppm of activated carbon produced from coconut shell by batch equilibrium test. In spite of the high concentration of natural ion exchangers, the percentages of adsorption of these complexes were not observed to be very high. (author)