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Commission of the European Communities, Karlsruhe (F.R. Germany). European Inst. for Transuranium Elements; Paper 4; 1975; 5. international conference on plutonium and other actinides; Baden-Baden, F.R. Germany; 10 Sep 1975; AED-CONF--75-417-004; Short communication only.
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[en] The intermolecular kinetic isotope effect for the title reaction has been investigated using a moderated nuclear recoil technique. The following Arrhenius temperature dependence was obtained: k)2/k)2 = (1.04plus-or-minus0.06)exp(382plus-or-minus35)/RT. This result is in quantitative agreement with an independent study based upon a discharge flow reactor method. The advantages and limitations of the nuclear recoil procedure are considered, and relevant literature results are critically reviewed
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Journal of Chemical Physics; v. 63(7); p. 2970-2979
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[en] Isotope effects were investigated at the surface of aqueous lithium and calcium salt solutions. The dependence on the temperature in the gas phase was determined. The surfaces of the solutions were isolated by spray experiments. In the case of calcium salt solutions an enrichment of the lighter isotope 40Ca in relation to the heavier isotopes 44Ca and 48Ca was found at the solution surface. The experiments with lithium fluoride and lithium iodide gave inverse isotope effects. The calcium isotope effect could be qualitatively explained by the Gibbs theorem. The isotope separation of lithium possibly can be referred to the more covalent than ionic bonding character of lithium compounds at the solution surface. (orig.)
[de]
Isotopieeffekte wurden in der Grenzschicht von waessrigen Lithium- und Calciumsalzuntersuchungen untersucht. Die Abhaengigkeit des Isotopieeffektes von der Temperatur in der Gasphase wurde ueberprueft. Die Grenzflaechen der Loesungen wurden durch Blasenspruehversuche isoliert. Bei Calciumsalzloesungen fand sich eine Anreicherung des leichteren Isotops 40Ca gegenueber den schweren Isotopen 44Ca und 48Ca an der Grenzflaeche der Loesung. Bei den Experimenten mit Lithiumfluorid und Lithiumjodid ergab sich eine Inversion des Isotopieeffekts. Der Calcium-Isotopieeffekt konnte qualitativ mit dem Gibbs-Theorem erklaert werden. Die Isotopentrennung von Lithium kann moeglicherweise auf den mehr kovalenten als ionischen Bindungscharakter der Lithiumverbindungen an der Grenzflaeche der Loesung zurueckgefuehrt werden. (orig./AK)Original Title
Isotopieeffekte in der Grenzschicht anorganischer Loesungen
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6 figs.; 2 tabs.; 20 refs.
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Z. Naturforsch., B; v. 30(4); p. 497-502
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[en] When boron nitride is phosphidized over the temperature range 800-9000C, with holding for 1 to 4 hours, the material obtained is a multiphase system, the chief component of which is BN. P2O5, BP, and PON were detected radiographically, and the type of photoluminescent spectrum exhibited by this material was found to depend on its phase composition. (author)
Original Title
Lyuminestsentnye svojstva produktov fosfidizatsii BN
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For English translation see the journal Inorg. Mater.
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Izvestiya Akademii Nauk SSSR, Neorganicheskie Materialy; v. 11(6); p. 1041-1044
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[en] A medium-pressure (1 Torr), large-diameter (10 cm) flow tube has been used to measure rate coefficients at 298 degreeK for (a) total relaxation (sum of vibrational--vibrational and vibrational--rotational, translational processes) of HF(v=1, 2, 3, 4, and 5) by HF, (b) relaxation of DF(1, 2, 3, and 4) by HF, and (c) over-all relaxation of DF(v=1, 2, 3, and 4) by D2. The chemically produced vibrationally excited HF or DF species have been studied by monitoring their vibrational--rotational emission in a fast-flow system. The rate coefficient for the relaxation of HF(1) by HF is 5.3times104 sec-1center-dotTorr-1. The measured rate coefficients for the deexcitation of HF(v=2, 3, 4, and 5) by HF are 5.3times105, 8.5times105, 8.8times105, and 2.8times105 sec-1center-dotTorr-1, respectively. The rate coefficients for the vibrational--rotational, translational deexcitation from the upper vibrational levels of DF(v) by HF are found to have a nonlinear vibrational dependence. The rate coefficient for the relaxation of DF(v=1) by D2 is 1.35times104 sec-1center-dotTorr-1
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Journal of Chemical Physics; v. 63(6); p. 2453-2460
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AbstractAbstract
No abstract available
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1975; 1 p; 4. international transplutonium element symposium; Baden-Baden, F.R. Germany; 13 Sep 1975; Short communication only. Available from ZAED. Proceedings will be published.
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[en] The intermolecular deuterium isotope effect for the photoinitiated bromination of cyclohexane and perdeuteriocyclohexane was determined in the vapor phase and in solution. Under conditions where the radicals formed do not transfer with hydrogen or deuterium bromide, a value for the vapor phase reaction of k/sub RH/k/k/sub RD/ = 5.4 +- 0.2 (20.80) was found. In solution at concentrations of bromine (0.07-3.6 M) which are high enough to stop the transfer of the radicals that are free of the solvent cage, with the low concentrations of hydrogen or deuterium bromide formed at low conversion, the value obtained for k/sub RH//k/sub RD/ = 4.3 +- 0.2. The difference between the vapor phase and solution results is attributed to a cage reversal reaction, between the radical hydrogen bromide pair, that is competitive with diffusion. At concentrations of molecular bromine (10-18 M) that are high enough to scavenge radicals from the solvent cage, the value obtained for k/sub RH//k/sub RD/ is the same as that found in the vapor phase. Under conditions where mixtures of the reactants (C6D12:C6H12:Br2, 1:1:1) were allowed to completely react the value determined for k/sub RH//k/sub RD/ = 3.1 +- 0.01 can be attributed to both internal and external reversal reactions. (auth)
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Journal of the American Chemical Society; v. 97(21); p. 6162-6165
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[en] Sections for the system Eu2O3-Gd2O3-Ta2O5 containing 25, 50 and 75 mol.%. Ta2O5 at 12500C were studied by the X-ray, electron-microscope and luminescent techniques. It was established that there exist solid solutions with a cubic, monoclinic and rhombic type base, respectively, throughout the X value interval for (Eusub(x)Gdsub(1-x)3 TaO7, Eusub(x)Gdsub(1-x) Ta3O9, and Eusub(x)Gdsub(1-x) TaO4. The variation in elementary cell parameters does not obey Vegard's law. The anomalies in variation as x increases are observed close to X=0.15 and 0.35. (author)
Original Title
Sistema Eu2O3-Gd2O3-Ta2O5 pri soderzhanii Ta2O5 25,50 i 75 mol.%
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For English translation see the journal Inorg. Mater.
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Journal Article
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Izvestiya Akademii Nauk SSSR, Neorganicheskie Materialy; v. 11(6); p. 1053-1055
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AbstractAbstract
No abstract available
Source
1975; 1 p; 4. international transplutonium element symposium; Baden-Baden, F.R. Germany; 13 Sep 1975; Short communication only. Available from ZAED. Proceedings will be published.
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[en] The design, fabrication, and operation of a special plant growth chamber system utilized in the biosynthesis production of 14C labeled tobacco plant material are described. The controlled environmental factors of the system were relative humidity, temperature, carbon dioxide, nutrients and auxiliary lighting. Four plants of Nicotiana tabacum L. cv. Coker 254 were grown for five weeks in the 14CO2 atmosphere of the growth chamber. The four-plant harvest produced a total dry weight yield of 420 g of uniformly labeled 14C-tobacco plant material with an average specific activity of 614 nCi/mg of carbon. (author)
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International Journal of Applied Radiation and Isotopes; v. 26(12); p. 753-757
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