Study of Actinides

Microchemical or ultramicrochemical techniques are used extensively ia chemical studies of actinide elements (16). If extremely small volumes are used, microgram or lesser quantities of material can give relatively high concentrations in solution. Balances of sufficient sensitivity have been developed for quantitative measurements with these minute quantities of material. Since the amounts of material involved are too small to be seen with the unaided eye, the actual chemical work is usually done on the mechanical stage of a microscope, where all of the essential apparatus is in view. Compounds prepared on such a small scale are often identified by x-ray crystallographic methods. 

Studies of actinide photochemistry are always dominated by the reactions that photochemically reduce the uranyl, U(VI), species. Almost any UV-visible light will excite the uranyl species such that the long-lived, 10-lt seconds, excited-state species will react with most reductants, and the quantum yield for this reduction of UQ22+ to U02+ is very near unity (8). Because of the continued high level of interest in uranyl photochemistry and the similarities in the actinyl species, one wonders why aqueous plutonium photochemistry was not investigated earlier. 

Storage, nuclear waste, x-ray photoemission spectroscopic study of actinides in silicate-based... 

In Chap. E, photoelectron spectroscopic methods, in recent times more and more employed to the study of actinide solids, are reviewed. Results on metals and on oxides, which are representative of two types of bonds, the metallic and ionic, opposite with respect to the problem itineracy vs. localization of 5f states, are discussed. In metals photoemission gives a photographic picture of the Mott transition between Pu and Am. In oxides, the use of photoelectron spectroscopy (direct and inverse photoemission) permits a measurement of the intra-atomic Coulomb interaction energy Uh. 

Glagovsky, E. M., Yudintsev, S. V., Kuprin, A. V., Pelevin, L. P., Konovalov, E. E., Velichkin, V. I. Myasoedov, B. F. 2001. A study of actinide crystalline matrices produced by self-sustaining high-temperature synthesis. Radiochemistry, 43, 557-562 (in Russian). 

Studies of Actinide Sorption on Selected Geologic Materials... 

Density functional theory (DFT) has been used extensively for the theoretical study of actinide complexes, making it one of the few first-principles methods that can... 

Guillaumont, D. 2004. Quantum chemistry study of actinide(III) and lanthanide(III) complexes with tridentate nitrogen ligands. Journal of Physical Chemistry 108(33) 6893-6900. 

Hydrolysis reactions are common to all actinide ions in nearneutral solutions, and take place either in parallel with or predominantly over other complexation reactions. In connection with the migration studies of actinide ions in natural waters, attention recently has been focused on hydrolysis reactions of actinides since these reactions are important in determining the solubility of the actinide hydroxide or oxide. Although numerous studies have been made (1-4) to determine stability constants of various hydrolysis products, much of the necessary data are still lacking. The acquisition of these data and further improvement or verification of the existing data is desirable. 

Sajun, M. S. Radiochemical Study of Actinide Elements, Ph.D. Thesis, Bombay Univ. 1981... 

Silva RJ, Benson LV, Apps JA. 1979. Studies of actinide sorption on selected geologic materials. ACS Symp Ser 100 215-240. 

Comparative Performances of Some Substituted CMP, CMPO, and Diamides Used as Carriers in SLM Studies of Actinides and Lanthanides... 

Plutonium(in)-ion selective electrode consisting of phosphine oxides such as bis-(diphenylphosphoiyl)-methane as an ionophore was developed by Kitatsuji et al. [98], The Pu(lll)-1SE prepared exhibited Nemstian response to the concentration of Pu in the sample solution. Interference of UOafVl), U(1V), NpOafV), and Pu(lV) was investigated. Cristau et al. [99] have carried out extraction as well as permeation studies of actinides such as neptunium, plutonium, and americium using polyphosphine polyoxides with (O)PCP(O) linkage, which exhibit very high selectivity. 

The separation of actinides has been studied for various purposes in Japan Atomic Energy Research Institute (JAERI). The works which have been carried out so far, are classified into four categories preparation studies of actinides nuclides, separation chemistry for chemical analysis, separation of actinides from radioactive waste, and studies on reprocessing of spent nuclear fuels. The present work is to review studies of actinide separation performed in JAERI, emphasizing the need of the separation for the main purpose of individual. Concern is focussed on the separation of transuranium elements and studies on thorium and uranium are put aside. 

R520 W. Runde, Spectroscopies for Environmental Studies of Actinide Species , Los Alamos Sci., 2000, 26,412... 

The application of theoretical electronic structure methods to organoactinide complexes has long been hampered by some well-known challenges. Before we detail the computational methodology used in the present studies, we will briefiy summarize some of the particular challenges inherent in the theoretical study of actinide complexes ... 

J Li, BE Bursten. Relativistic Density Eunctional and Ab initio Theoretical Studies of Actinide Eluorides. Book of Abstracts, 217th National ACS Meeting, Anaheim, CA, 1999, NUCL 174. 

Environmental behavior of actinides includes studies of actinide interactions related to geochemistry actinide interactions with microbes and actinide redox reactions, speciation, and complexation. 

Choppin, G.R. and Unrein, P.J., "Thermodynamic Study of Actinide Fluoride Complexation", Transplutonium Elements, W. 

In this paper, we shall present a brief overview of the application of photoelectron spectroscopy to the study of actinide materials. Some phenomenology will be discussed as will studies of specific materials. Only illustrative examples will be presented (4). 

In the optical studies of actinide ions which have been reported, proper cognizance of covalency effects has not in general been shown, so that no reliable estimates of its extent are available. In this work we reexamine some of the optical data using a molecular orbital approach. For simplicity, we limit ourselves at the present time to octahedral 5p complexes. The most... 

Choppin, G. R., Umein, P. J., Thermodynamic study of actinide fluoride complexation, Transplutoiuum 1975 Proc. Symp. Baden Baden, Germany, Sept. 13-17, 1975, 4th Int. Transplutoiuum Symp., pp.97-107, North-Holland Publ., Amsterdam, Holland, (1976). Cited on pages 207, 208, 209, 212, 213, 222, 557, 558, 599,603. 

In summary, the calculations on this special impurity system, with only one open-shell electron and simple manifolds, in which the assigmnents of the 5/<-> 6d absorption/emission bands were specially clear, even though not complete, and where absorption/emission bands built on a single origin and recorded with an extremely hi resolution exist, allow to be initially optimistic in the evaluation of the applicability of present day ab initio methods of the Quantum Chemistry in structural and spectroscopic studies of actinide ion impurities in ionic crystals. The quality of the approximate Hamiltonians and of the approximate procedures for decoupling the treatment of electron correlation and spin-orbit seems to be acceptable. The performance in other impurities with several open-shell electrons and large manifolds will be presented in the next two sections. 

Choppin G, Morse J. 1987. Laboratory studies of actinides in marine systems. In Pinder J, et al., eds. Environmental research on actinide elements. Office of Science and Technical Information. 

In studies of Actinide and Fission Product transmutation interest has been focused on accelerator driven subcritical systems which are of particular interest if one considers fast actinide burners where the fissile isotopes of Neptunium, Americium, and Curium have a considerably smaller fraction of delayed neutron emitters (compared to the more common fuels U-238 and U-235), a small Doppler effect and a possibly positive coolant void coefficient. This poses a particular problem of control since the fraction of delayed neutrons is essential for the operation of a nuclear reactor in the critical state. 

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