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  • Author or Editor: O. Constantinescu x
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Abstract  

Electron spin resonance spectra of free radicals formed in the radiolysis of benzen-2,1-diazoquinone-4-sulphonic acid in polycrystalline form have been recorded. Two different radical species were found; the first one was stable at 77 K, whereas the second one was formed at higher temperatures. The thermal stability of the latter was investigated in the 20–100 °C temperature range, and the kinetic parameters for the decomposition process were determined. An appropriate mechanism of radiolysis was proposed.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: A. Olariu, M. Constantinescu, O. Constantinescu, T. Badica, I. Popescu, C. Besliu, and D. Leahu

Abstract  

Radiochemical neutron activation analysis has been applied to investigate the microelements in gold samples with archaeological importance. Chemical separation has allowed the determination of traces of Ir, Os, Sb, Zn, Co, Fe, Ni. Instrumental neutron activation analysis has been used for the determination of Cu.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: R. Georgescu, A. Pantelica, M. Salagean, D. Craciun, M. Constantinescu, O. Constantinescu, and P. Frangopol

Abstract  

Hair samples were collected from 20 metallurgical workers (10 males and 10 females) and from 59 control subjects (32 males and 27 females), whose jobs do not indicate a specific occupational exposure. The concentrations of ten minor and trace elements (Al, Co, Cu, Fe, Mg, Mn, Sb, Se, V and Zn) were determined by instrumental neutron activation analysis (INAA). The statistical data distributions, the sex and age influences in these elemental concentrations and the average values obtained for the control group were compared with published data. The effect of occupational exposure to the metallic elements was reflected in elemental composition of hair by significant higher concentration levels of Al, Co, Cu, Fe, Mg, Mn, Sb, V and Zn in the hair of the exposed group, when compared with the control group.

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Abstract  

Zinc and nickel hexacyanoferrates (II) present a high affinity for223Fr and no retention for223Ra in hydrochloric acid solutions with concentrations greater than 0.5N. Hydrated antimony pentoxide is the best sorbent for223Ra. Incorporated in a composite exchanger, it could be used for decontamination purposes.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: Z. Szeglowski, L. Guseva, Dinh Thi Lien, V. Domanov, B. Kubica, G. Tikhomirowa, O. Constantinescu, M. Constantinescu, and A. Yakushev

Abstract  

The short-lived isotopes of W and their descendants have been separated from nuclear reaction products arising in the bombardment of samarium target with24Mg ions at the U-400 cyclotron of JINR-Dubna. Chemical separations were performed using previously elaborated fast and continuous ion exchange. In similar way products of235U fission, obtained at the microtron MT-25 during irradiation of235U target with photoneutrons were separated.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: F. Monroy-Guzman, D. Trubert, L. Brillard, J. Kim, M. Hussonnois, and O. Constantinescu

Abstract  

The behaviour of the elements Zr, Hf, Nb, Ta and Pa has been investigated on macroporous anion exchange resin BIORAD AGMP 1 in HF medium (from 0.02 to 2M). All the studied elements show strong adsorption properties at low HF concentration. The adsorption was found to be highly dependent on H+ and F concentrations. The distribution of possible adsorbable complexes is discussed.

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Abstract  

Neutron activation analysis has been applied to determine the purity of super-enriched176Yb as well as a diagnostic to optimize yields from the P.A.R.I.S. mass separator at Orsay. In 25 mass separations carried out during 3 months, 910 mg of super-enriched176Yb2O3 were recovered from the original 7 g of176Yb2O3 (97.5% enrichment). Neutron activation analysis has shown that only two per thousand of the initially present174Yb remained in the super-enriched product. Using this176Yb super-enriched (99.998%) target, micro-quantities of the high spin (16+) isomer178m2Hf were produced by the (,2n) reaction at the U-200 cyclotron in Dubna. Quantities of about 2·1012 atoms of this isomer have been irradiated by thermal neutron at the ORPHEE Reactor, Saclay. Only the neutron capture giving rise to the isomeric state 25/2 of179Hf has been measured, by detection -rays of this 25.1 days isomer. A cross section of 45±5 barns was obtained for178m2Hf(n,)179m2Hf.

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Journal of Radioanalytical and Nuclear Chemistry
Authors: D. Trubert, M. Hussonnois, L. Brillard, J. Kim, V. Barci, G. Ardisson, Z. Szeglowski, and O. Constantinescu

Abstract  

The (EC, +) decay of168Hf, produced by the156Gd (16O,4n) reaction, has been studied, with high efficiency HPGe coaxial detectors, using on-line measurements with the RACHEL setup. Off-line measurements were also carried out using catcher collection technique. Energies and intensities of 119 -lines are reported among these only two were known in the earlier study ofChu andReednick. The168Lu level scheme built on the basis of single - and X-spectra and - coincidence measurements, allows the interpretation of 79 -transitions, between 38 excited states reported for the first time.

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Abstract  

A method for deep decontamination of high spin178m2Hf isomer from microquantities of Sc, Fe, Co, Ni, Sb and Ag was elaborated using ion exchange separation on Dowex-1 in Hf and CH3COOH–HCl media.

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