An X-Ray Spectrometric Method for Determination of Plutonium in Solution

It is shown that the method of x-ray emission spectrometry can be extended advantageously to the determination of plutonium in solution, Since K and L x-ray emission from the elements of higher atomic number is not measurably influenced by valence state of the emitting atom or ion, this physical method is especially attractive for elements such as plutonium whose chemistry is intricate and whose chemical analysis is complicated by several valence states existing in solution. Nor is it affected by variations in isotopic content as is the widely used radiochemical assay for plutonium. With a total amount of plutonium between 0.4 and 0.8 mg the standard deviation of a single result is less than 1 per cent. For samples of diverse origin interferences are eliminated, usually by simple chemical pre-treatment or by separation procedures, to give a clean solution for analysis. On the other hand, for large numbers of samples with a comparable matrix, it is worthwhile to devise calibration standards so that such samples can be analyzed directly. (auth

Novel structures and energy spectra of hydroxylated (Si O2) 8 -based clusters:Searching for the magic (Si O2) 8 O2 H3- cluster

The prominent (SiO2)8O2H3? mass peak resulting from the laser ablation of hydroxylated silica, attributed to magic cluster formation, is investigated employing global optimization with a dedicated interatomic potential and density functional calculations. The low-energy spectra of cluster isomers are calculated for the closed shell clusters: (SiO2)8OH? and (SiO2)8O2H3? giving the likely global minima in each case. Based upon our calculated cluster structures and energetics, and further on the known experimental details, it is proposed that the abundant formation of (SiO2)8O2H3? clusters is largely dependent on the high stability of the (SiO2)8OH? ground state cluster. Both the (SiO2)8O2H3? and (SiO2)8OH? ground state clusters are found to exhibit cagelike structures with the latter containing a particularly unusual tetrahedrally four-coordinated oxygen center not observed before in either bulk silica or silica clusters. The bare ground state (SiO2)8O2? cluster ion core is also found to have four tetrahedrally symmetric Si?O terminations making it a possible candidate, when combined with suitable cations, for extended cluster-based structures/materials.Applied Science

The x-ray spectrometric determination of uranium in solution /

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