Arsenic nuclear properties

Helium-3 [14762-55-1], He, has been known as a stable isotope since the middle 1930s and it was suspected that its properties were markedly different from the common isotope, helium-4. The development of nuclear fusion devices in the 1950s yielded workable quantities of pure helium-3 as a decay product from the large tritium inventory implicit in maintaining an arsenal of fusion weapons (see Deuterium AND TRITIUM) Helium-3 is one of the very few stable materials where the only practical source is nuclear transmutation. The chronology of the isolation of the other stable isotopes of the hehum-group gases has been summarized (4). 

Trimethoxyarsine (dj 1.4264 ng 1.4402) is a colorless liquid which is readily hydrolyzed by atmospheric moisture, forming a white precipitate of arsenic trioxide. The compound is soluble in carbon tetrachloride, benzene, chloroform, hydrocarbons, and ethers. The product is shown to be at least 99.5% pure (with respect to hydrogen-containing impurities) by proton nuclear magnetic resonance (n.m.r.), since a single sharp peak at —3.52 p.p.m. (relative to internal tetramethylsilane) is seen in the n.m.r. spectrum of the neat liquid. Similar properties are shown by triethoxyarsine (d 1.2132 ng 1.4360) and tri- i-butoxyarsine (dj 1.0723 nj 1.4476). 

Theoretical studies of the properties of the individual components of nanocat-alytic systems (including metal nanoclusters, finite or extended supporting substrates, and molecular reactants and products), and of their assemblies (that is, a metal cluster anchored to the surface of a solid support material with molecular reactants adsorbed on either the cluster, the support surface, or both), employ an arsenal of diverse theoretical methodologies and techniques for a recent perspective article about computations in materials science and condensed matter studies [254], These theoretical tools include quantum mechanical electronic structure calculations coupled with structural optimizations (that is, determination of equilibrium, ground state nuclear configurations), searches for reaction pathways and microscopic reaction mechanisms, ab initio investigations of the dynamics of adsorption and reactive processes, statistical mechanical techniques (quantum, semiclassical, and classical) for determination of reaction rates, and evaluation of probabilities for reactive encounters between adsorbed reactants using kinetic equation for multiparticle adsorption, surface diffusion, and collisions between mobile adsorbed species, as well as explorations of spatiotemporal distributions of reactants and products. 

Confirmation of the structure proposed for Cgo required isolation of enough material to allow the arsenal of modern techniques of structure determination to be applied. A quantum leap in fullerene research came in 1990 when a team led by Wolfgang Kratschmer of the Max Planck Institute for Nuclear Physics in Heidelberg and Donald Huffman of the University of Arizona successfully prepared buckminsterfullerene in amounts sufficient for its isolation, purification and detailed study. Not only was the buckminsterfullerene structure shown to be correct, but academic and industrial scientists around the world seized the opportunity afforded by the availability of Ceo in quantity to study its properties. 

Boron—along with silicon, germanium, arsenic, antimony, and tellurium—is one of a few elements, called metalloids, with properties intermediate between those of metals and nonmetals. Although they have a luster like metals, metalloids do not form positively charged ions (cations). The melting temperature of boron is very high, 2190°C. Boron is added to copper, aluminum, and steel to improve their properties. It is used in control rods of nuclear reactors because of the good neutron-... 

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