Nuclides, properties

Four appendixes list fundamental physical constants, conversion tables, nuclide properties, and radioactivity concentration limits for nuclear plant effluents. 

Mother nuclide Decay properties Daughter Decay nuclide properties Application... 

Several portions of Section 4, Properties of Atoms, Radicals, and Bonds, have been significantly enlarged. For example, the entries under Ionization Energy of Molecular and Radical Species now number 740 and have an additional column with the enthalpy of formation of the ions. Likewise, the table on Electron Affinities of the Elements, Molecules, and Radicals now contains about 225 entries. The Table of Nuclides has material on additional radionuclides, their radiations, and the neutron capture cross sections. 

Potzel et al. [Ill] have established recoil-free nuclear resonance in another ruthenium nuclide, ° Ru. This isotope, however, is much less profitable than Ru for ruthenium chemistry because of the very small resonance effect as a consequence of the high transition energy (127.2 keV) and the much broader line width (about 30 times broader than the Ru line). The relevant nuclear properties of both ruthenium isotopes are listed in Table 7.1 (end of the book). The decay... 

The uranium and thorium decay-series contain radioactive isotopes of many elements (in particular, U, Th, Pa, Ra and Rn). The varied geochemical properties of these elements cause nuclides within the chain to be fractionated in different geological environments, while the varied half-lives of the nuclides allows investigation of processes occurring on time scales from days to 10 years. U-series measurements have therefore revolutionized the Earth Sciences by offering some of the only quantitative constraints on time scales applicable to the physical processes that take place on the Earth. 

Knowledge of the chemical properties of the U-series nuclides is essential to any understanding of fractionation within the U-series chains. The nuclides of particular... 

In this section, we review some basic chemical properties of these nuclides. Much of this material can also be found in Ivanovich and Harmon (1992). 

Table 1. Chemical properties of the main U-series nuclides...

Most of the U-series nuclides are metals. Five of them belong to the actinide family corresponding to the filling of the internal orbitals while the orbitals 7s are filled. A sixth, Ra is an alkali earth and shares some chemical properties with other alkali earths, particularly the heavier ones (Sr and Ba), while a seventh, Rn, is a noble gas. The filling of the orbitals prescribes the possible oxidation states of these elements. Their preferred oxidation state is obtained when the electronic configuration is that of the closest rare gas (Rn). 

The thermodynamic properties of U-Th series nuclides in solution are important parameters to take into account when explaining the U-Th-Ra mobility in surface environments. They are, however, not the only ones controlling radionuclide fractionations in surface waters and weathering profiles. These fractionations and the resulting radioactive disequilibria are also influenced by the adsorption of radionuclides onto mineral surfaces and their reactions with organic matter, micro-organisms and colloids. 

Isotope distribution among the different phases of water are generally assumed to mostly depend on the behavior of their respective parent nuclides, in particular on their sorption/solubility properties. For instance, according to Sarin et al. (1990), covariation between ratios and Th/U ratios in Himalayan rivers reflect the preferential... 

Isomers—Nuclides having the same number of neutrons and protons but capable of existing, for a measurable time, in different quantum states with different energies and radioactive properties. Commonly the isomer of higher energy decays to one with lower energy by the process of isomeric transition. 

Isotopes—Nuclides having the same number of protons in their nuclei, and hence the same atomic number, but differing in the number of neutrons, and therefore in the mass number. Identical chemical properties exist in isotopes of a particular element. The term should not be used as a synonym for nuclide because isotopes refer specifically to different nuclei of the same element. 

The numerical combination of protons and neutrons in most nuclides is such that the nucleus is quantum mechanically stable and the atom is said to be stable, i.e., not radioactive however, if there are too few or too many neutrons, the nucleus is unstable and the atom is said to be radioactive. Unstable nuclides undergo radioactive transformation, a process in which a neutron or proton converts into the other and a beta particle is emitted, or else an alpha particle is emitted. Each type of decay is typically accompanied by the emission of gamma rays. These unstable atoms are called radionuclides their emissions are called ionizing radiation and the whole property is called radioactivity. Transformation or decay results in the formation of new nuclides some of which may themselves be radionuclides, while others are stable nuclides. This series of transformations is called the decay chain of the radionuclide. The first radionuclide in the chain is called the parent the subsequent products of the transformation are called progeny, daughters, or decay products. 

Very hard, steel-gray metal. Hardens platinum. The International Prototype Meter in Paris consists of a Pt-Ir alloy. Its hardness and corrosion resistance is exploited in fountain-pen tips, spark plugs in powerful engines (airplanes), and electrical contacts. Used as a material in shells for nuclide batteries in satellites. Responsible for the iridescent properties of vapor-treated sunglasses. 

Both polonium nuclides are alpha emitters and therefore of particular concern. In health physics it is customary to differentiate between attached and unattached 218Po the former, usually the larger of the two consists of 218Po atoms attached to airborne particles which are copiously present in virtually every atmosphere the latter consists of a 218Po atom or ion, frequently surrounded by several dozen molecules of a condensible species present in the air. The purpose of this paper is to present a new method for measuring the size properties of these unattached 218Po clusters. 

G. W. C. Kaye and T. H. Laby, Tables of Physical and Chemical Constants, Longman 1995, gives a table of properties of the nuclides including isotopic abundance or half-life, decay modes, mass excess, neutron capture cross-section and ground-state spin and parity. This publication, with a prospect of regular updates, is available on the website http //www.kayelaby.npl.co.uk/. 

The modes of formation and radioactive properties of some of the principal transuranic nuclides are presented in Table 1. 

One striking exception was the very early discovery of I decay to Xe (Jeffery and Reynolds 1961). This discovery reflects the particular properties of rare gases which are nearly absent in telluric planetary bodies. Because they are not diluted by high abrmdances of isotopically normal noble gases, anomalies in rare noble gas components were the first to be detected. This is also the reason for the Xe record of the fission of Pu (Rowe and Kuroda 1965). From the available data on short-lived nuclides at that time, it was concluded that the last nucleosynthetic input into the protosolar cloud predated the formation of the planets by 100-200 Ma. 

Examination of the electronic states of catalysts and of rare earth dopants in phosphors are other applications which come to mind. When more is known about some of the yet unexplored properties of other possible Mossbauer nuclides, Mossbauer spectroscopy bids fair to being a powerful tool in rare earth chemistry. 

Due to its excellent SjN enhancement properties, LR-CPMG detection is probably the only possible choice when the primary SjN ratio is very small. This regards in particular measurements of low-abundance nuclides and nuclides with low gyromagnetic ratio. 

Table 11.3 General classification of nuclides significance of parity is related to symmetry properties of nnclear wave fnnctions. A nuclide is said to have odd or even parity if the sign of the wave fnnction of the system respectively changes or not with changing sign in all spatial coordinates (see Friedlander et ah, 1981 for more detailed treatment). The value assigned to dxA is appropriate for A > 80. For < 60, a value of 65 is more appropriate.

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