caa a22 4500 469110619 CHVBK 20180323133109.0 cr unu---uuuuu 170328e19921201xx s 000 0 eng 10.1007/BF02034798 doi (NATIONALLICENCE)springer-10.1007/BF02034798 Kinetics and mechanism of photoaccelerated isotope exchange between U(VI) and U(IV) in oxalate solutions [Elektronische Daten] [I. Shaban, M. Owreit, S. Nikitenko] A kinetic study of thermal and photoaccelerated U(IV)-U(VI) isotope exchange has been carried out in oxalate solutions at 11-40°C. The rate and quantum yield were determined as a function of U(IV), U(VI) and oxalate concentration, wavelength of incident light, temperature and absorbed dose of γ-radiation. The kinetic equations for thermal and photoaccelerated exchange have been obtained. It was assumed that the mechanism of exchange involves formation of U(V) as an intermediate, followed by slow exchange between U(V) and U(IV). The isokinetic dependence confirms the identity of limiting stages for thermal and photostimulated exchange. The upper component of photoexcited T1 level of uranyl is supposed to be the most reactive in the process of U(V) generation. It was observed that the small doses of γ-radiation evoke the acceleration of isotope exchange, however, at D>100 krad the rate of exchange is reduced to the level of thermal exchange. Akadémiai Kiadó, 1992 Shaban I. Tajura Research Center, Tripoly, Libya aut Owreit M. Tajura Research Center, Tripoly, Libya aut Nikitenko S. Institute of Physical Chemistry of Russian Academy of Science, Leninsky pr., 31, 117915, Moscow, Russia aut Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 163/2(1992-12-01), 245-253 0236-5731 163:2<245 1992 163 10967 https://doi.org/10.1007/BF02034798 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/BF02034798 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Shaban I. Tajura Research Center, Tripoly, Libya aut NATIONALLICENCE 700 1- Owreit M. Tajura Research Center, Tripoly, Libya aut NATIONALLICENCE 700 1- Nikitenko S. Institute of Physical Chemistry of Russian Academy of Science, Leninsky pr., 31, 117915, Moscow, Russia aut NATIONALLICENCE 773 0- Journal of Radioanalytical and Nuclear Chemistry Kluwer Academic Publishers 163/2(1992-12-01), 245-253 0236-5731 163:2<245 1992 163 10967 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer