Nuclear properties of isotopes

The title indicates the scope of the text. The term isotope effects is used rather than applications of isotopes to indicate clearly that it deals with differences in the properties of isotopically substituted molecules, for example differences in the chemical and physical properties of water and the heavy waters (H2O, HDO, D2O, HTO, etc.). Thus H20, HDO and D2O have different thermodynamic properties. Also reactions in solvent mixtures of light and heavy water proceed at different rates than they do in pure H2O. On the other hand, the differences are not large and consequently, to the extent the difference in properties can be ignored, HDO or HTO can be used as tracers for H2O. An important point, however, is that this book does not deal with isotopes as tracers in spite of the widespread importance of tracer studies, particularly in the bio and medical sciences. Also the title specifically does not mention physics which would necessarily have been included if the term Physical Sciences had been used. Thus the text does not deal with differences in the nuclear properties of isotopic atoms. Such differences are in the realm of nuclear physics and will not be discussed. 

The development of collinear laser spectroscopy has enabled measurements of isotope shifts and hyperfme stmcture over long chains of isotopes. This makes it possible to derive nuclear properties of isotopes far from stability. The experimental development is reviewed and some future prospects discussed. 

Table 3.1. The nuclear properties of isotopes of interest to polymer chemists...

E. K. Hyde, I. Perlman, and G. T. Seaborg, The Nuclear Properties of the Heavy Elements, Prentice-Hall, Englewood Cliffs, N.J., 1964 E. Browne, R. B. Firestone, and V. S. Shirley, eds.. Table of Radioactive Isotopes,John Wiley Sons, Inc., New York, 1986. 

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 ground- and excited-state magnetic moments ji are tabulated as /ig = 0.09062(3) n.m. (nuclear magnetons, /i ) and jig, = 0.1549 n.m., respectively (see Table Properties of Isotopes Relevant to Mdssbauer Spectroscopy provided by courtesy of Professor J. G. Stevens, Mdssbauer Effect Data Center, cf. CD-ROM). Considering that nuclear magnetic moments are given by the relation p, = giPj I, the nuclear g factors for Ee with /g = 1/2 and 1 = 3/2 are gg = 0.09062 X 2 and ge = 0.1549 x 2/3. With these values and taken from... 

D.C. Hess, J.R. Huizenga, M. G. Inghram, A.H. Jaffey, L.B. Mag-nusson, W. M. Manning, J.F. Mech, G. L. Pyle, R. Sjoblom, C.M. Stevens and M. H. Studier The formation of higher isotopes and higher elements by reactor irradiation of Pu23 some nuclear properties of the heavier isotopes. Peaceful uses of atomic energy 7, 26f (paper 809). New York United Nations 1956. 

Table 23.2, records the nuclear properties of JH, 3H (T) and 13C isotopes being employed particularly in various arms of Life Sciences ... 

We have seen that isotope effects on the properties of atoms and molecules are usually small, and this is true for all except the lightest elements. Consequently separation of single isotopes from mixtures of isotopes or isotopomers is tedious and difficult. The difficulty is compounded by the fact that the desired isotope is often present at low or very low concentration in the starting material (normally a naturally occurring fluid, ore, or mineral). Even so, the nuclear properties of certain separated isotopes are enough different from their sisters to justify the (usually enormous) expense of preparing isotopically pure or nearly pure materials. Three important examples follow ... 

It is easy to see why the results of primordial nucleosynthesis, and in particular the final abundance of deuterium, should be so sensitive to the nucleonic density of the Universe. For this reason, deuterium, made up of one proton and one neutron, can be considered as an excellent cosmic densimeter. The disparate abundances for their part are related to specific nuclear properties of the isotopes under consideration. 

Actinides, the chemical elements with atomic numbers ranging from 89 to 103, form the heaviest complete series in the Periodic Table. They are radioelements, either naturally occurring or synthesized by nuclear reactions. Their predominant practical application depends on the nuclear properties of their isotopes decay, spontaneous or induced fission. Their chemical and physical properties reflect a very complex electronic structure, and their study and understanding are a challenge to experimentalists and theoreticians. 

Effect of Prolonged Irradiation. Optimum product enrichment requires irradiation to a thermal neutron exposure in the range of 1020 neutrons cm-2, depending on the nuclear properties of the isotope being used. 

Both NQR and ESR depend for their chemical significance on the nuclear moments of the isotopes present in the species under study. Table 1 therefore summarizes the nuclear properties of the stable halogen nuclei, together with those of the four other elements that are commonly found in organic compounds, namely C, H, N and O. 

The nuclear properties of carbon furnish one radioactive isotope, 14C, thatlives sufficiently long to participate in the carbon cycle of life. With its 5730-yr halflife,... 

Selected nuclear properties of the principal isotopes of berkelium are listed in Table I (6). In addition to these isotopes, ranging from mass numbers 240 to 251, there are spontaneously fissioning isomers known for berkelium mass numbers 242, 243, 244, and 245, all with half-lives of less than 1 /usee. Only 249Bk is available in bulk quantities for chemical studies, as a result of prolonged neutron irradiation of Pu, Am, or Cm (7). About 0.66 g of this isotope has been isolated from... 

The properties of isotopes. Packing fraction. Structure of atomic nuclei. Nuclear fission. Nuclear chain reaction. Manufacture of plutonium. Fission of U23 and Pu23 . Uranium reactors the uranium pile. Nuclear energy as a source of power. 

---