Isotopes and isomers

Nudide Production Atomic mass Spin and Parirv Hair-lifc Mode and energy [keV j of decay 

Small quantities (f.ig) of the three long-lived technetium isotopes Tc. and Tc were produced for the first lime by bombarding molybdenum metal with 22 VIeV protons [8. Small amounts of Te are also accessible by neutron irradiation of ruthenium 

However, gram and kilogram amounts can be obtained by fission of U with thermal neutrons in the high, cumulative fission yield of 6.13 atom% [12]. This fission yield results in the production of about 1 kg of Tc from 1 ton of uranium ( 3 % enriched in after burnup in a nuclear reactor [13. Reactors with a power of 100 MW produce about 2.5 g of - Tc per day [14], Tc is also formed in high yield (atom%) from thermal neutron fission of-- U (4.8), (5.9), and fast neutron fission of Pu (5.9), (6.3) and - Th (2.7) [15]. (Compared to the high fission yield 

The extraction of TCO4 with pyridine [17] appears to be one of the most suitable processes of recovering - Tc from the waste solutions of the nuclear fuel cycle. The 

The waste solution (Fig. 5.2.A) is evaporated and the cake containing Zr and Nb is removed. To separate Ru. iron(III) hydrated oxide is precipitated with ammonia. Rare earth metal ions arc removed by precipitation of the hydrated oxides with ammonia. Thereafter, alkaline earth metal ions including Sr are precipitated by add- 

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To understand the evaluation of a CLE, we need to introduce some terms The word isotopomer is a combination of the terms isotope, and isomer. An isotopomer is one of the different labeling states in which a particular metabolite can be encountered [248] that is, a molecule with n carbon atoms has 2" isotopomers. These are usually either depicted using outlined and filled circles for unlabeled and labeled atoms, respectively (see Fig. 14), or are described in text format for example, C 010 would be the isotopomer of a three-carbon molecule labeled at the second position. An isotopomer fraction is the percentage of molecules in this specific labeling state. The positional enrichment is the sum of all isotopomer fractions in which a specific carbon atom in a specific metabolite is labeled [248]. Consequently, the usage of isotopomers enables to account for more information While a molecule with n carbon atoms will yield n positional enrichments, there are 2 — 1 isotopomer fractions (the 2"th measurement is redundant as, by definition, isotopomer fractions must sum up to unity) [260],... 

H / Magnetic Electric 4 Number of resonated isotopes and isomers Ht... 

Except for lithium, all the alkali atoms have been studied with the method developped in 1974 Data on hundreds of isotopes and isomers are obtained Some of these data concerning the nuclear moments are theoretically analysed, see for example [CAM 80], [MOL 80],[EKS 78], [EKS 79] and[ RAG 79] ... 

One stable isotope Y and thirty-seven unstable isotopes and isomers have been characterized. All four halides of yttrium are known and are commonly prepared by dissolving the oxide in corresponding acids. 

Tc and other isotopes and isomers of technetium are nuclides of medium radio-toxicity [26] licensing limits, annual limits of intake and maximum permitted air concentrations arc compiled in Table 5.4.A. 

Laboratory processes have now extended the radioactive element mass numbers beyond 238 to about 280. Each element from atomic numbers 1 to 110 is known to have at least one radioactive isotope. As of December 2001, about 3286 isotopes and isomers were thought to be known and recognized. Many stable and radioactive isotopes are now produced and distributed by the Oak Ridge National Laboratory, Oak Ridge, Tenn., U.S.A., to customers licensed by the U.S. Department of Energy. 

Actinium — (Gr. aktis, aktinos, beam or ray), Ac at. wt. (227) at. no. 89 m.p. 1050°C, b.p. 3198°C sp. gr. 10.07 (calc.). Discovered by Andre Debierne in 1899 and independently by F. Giesel in 1902. Occurs naturally in association with uranium minerals. Thirty-four isotopes and isomers are now recognized. All are radioactive. Actinium-227, a decay product of uranium-235, is an alpha and beta emitter with a 21.77-year half-life. Its principal decay products are thorium-227 (18.72-day half-life), radium-223 (11.4-day half-life), and a number of short-lived products including radon, bismuth, polonium, and lead isotopes. In equilibrium with its decay products, it is a powerful source of alpha rays. Actinium metal has been prepared by the reduction of actinium fluoride with lithium vapor at about 1100 to 1300°C. The chemical behavior of actinium is similar to that of the rare earths, particularly lanthanum. Purified actinium comes into equilibrium with its decay products at the end of 185 days, and then decays according to its 21.77-year half-life. It is about 150 times as active as radium, making it of value in the production of neutrons. Actinium-225, with a purity of 99%, is available from the Oak Ridge National... 

Mendelevium — (Dmitri Mendeleev [1834-1907]), Md at. wt. (258) at. no. 101 m.p. 827°C valence +2, +3. Mendelevium, the ninth transuranium element of the actinide series to be discovered, was first identified by Ghiorso, Harvey, Choppin, Thompson, and Seaborg early in 1955 as a result of the bombardment of the isotope Es with helium ions in the Berkeley 60-inch cyclotron. The isotope produced was Md, which has a half-life of 78 min. This first identification was notable in that Md was synthesized on a one-atom-at-a-time basis. Nineteen isotopes and isomers are now recognized. Md has a half-life of 51.5 days. This isotope has been produced by the bombardment of an isotope of einsteinium with ions of helium. It now appears possible that eventually enough Md can be made so that some of its physical properties can be determined. Md has been used to elucidate some of the chemical properties of mendelevium in aqueous solution. Experiments seem to show that the element possesses a moderately stable dipositive (II) oxidation state in addition to the tripositive (III) oxidation state, which is characteristic of actinide elements. 

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