Helium isotope

Except for helium, all of the elements in Group 18 free2e into a face-centered cubic (fee) crystal stmeture at normal pressure. Both helium isotopes assume this stmeture only at high pressures. The formation of a high pressure phase of soHd xenon having electrical conductivity comparable to a metal has been reported at 33 GPa (330 kbar) and 32 K, and similar transformations by a band-overlap process have been predicted at 15 GPa (150 kbar) for radon and at 60 GPa (600 kbar) for krypton (51). 

Reaction (33.4.1) yields the helium isotope He and a neutron n reaction (33.4.2) yields tritium T and fight hydrogen (a proton) P, in both cases with the liberation of a huge amount of energy. 

Hilton DR, Barling J, Wheiler GE (1990) The effect of shallow-level contamination on the helium isotope systematics of ocean island lavas. Nature 348 59-62... 

The properties of the two helium isotopes in the liquid state are strongly influenced by quantum effects. In Fig. 2.8, the specific heat of 3He, calculated from the ideal gas Fermi model (Tp = 4.9 K) with the liquid 3He density, is compared with the experimental data. The inadequacy of this model is evident. A better fit, especially at the lower temperatures, is obtained by the Landau theory [25]. 

Nishio Y, Sasaki S, Gamo T, Hiyagon H, Sano Y (1998) Carbon and helium isotope systematics of North Fiji basin basalt glasses carbon geochemical cycle in the subduction zone. Earth Planet Sci Lett 154 127-138... 

Only one combination of four nucleons is bound, 4He, with two protons and two neutrons. All other combinations of four nucleons are unbound. Moreover, 4He, or the a particle, is especially stable (very strongly bound), and the nucleons are paired to give a total spin 5=0. Interestingly, if we add a nucleon of either type to the a particle, we produce an unbound nucleus Thus, there are no stable nuclei with A = 5 as both 5He and 5Li break apart very rapidly after formation. This creates a gap in the stable masses and poses a problem for the building up of the elements in stars, which is discussed in Chapter 12. There are two bound nuclei with A = 6, 6He and 6Li, with the helium isotope decaying into the lithium isotope, the others are unbound. Continuing on, between mass 6 and 209, all mass numbers... 

The second paper, in 1960, discusses the existence of nuclei at the threshold of stability having excessive numbers of neutrons [16 ]. Its most remarkable result was the prediction of a new helium isotope, Helium-8. This isotope was soon discovered experimentally and the decay chain was traced (due to the weak interaction 8He —> 8Li —+ 8Be with subsequent 8Be —> 24Be). 

Oxygen isotope signatures of Vesuvio rocks show wide variations (S180 —1-7.0 to +10.0) and are negatively correlated with MgO (Ayuso et al. 1998). Helium isotope studies on clinopyroxene and olivine from historical lavas gave values of R/Ra 2.2 to 2.7, close to ratios found in the fumar-oles of Campanian volcanoes (Tedesco et al. 1990 Graham et al. 1993). 

Graham D, Allard P, Kilbum CRJ, Spera F, Lupton JE (1993) Helium isotopes in some historical lavas from Mount Vesuvius. J Volcanol Geotherm Res 58 359-... 

Sano Y, Wakita H, Italiano F, Nuccio M (1989) Helium isotopes and tectonics in Italy. Geophys Res Lett 16 511-514... 

Figure 6.20 Distribution of helium isotopes in the crust of western Europe. KTB, the German deep-drilling site in Oberpfalz MB, Molasse Basin PB, Pannonian Basin RG, Rheingraben EG, Egergraben. Reproduced from Oxburgh and O Nions (1987).

Hilton, D. R., Craig, H. (1989) A helium isotope transect along the Indonesian archipelago. Nature, 342, 906-8. 

Marty, B., Torgersen, T., Meynier, V, O Nions, R. K., de Marsily, C. (1993) Helium isotope fluxes and groundwater ages in the Dogger Aquifer, Paris Basin. Water Resources Res., 29(4), 1025-35. 

Polak, B. G., Kononov, V I., Tolstikhin, I. N., Mamyrin, B. A., Khabarin, L. V (1975) The helium isotopes in thermal fluids. In Terrestrial and Chemical Problems of Thermal Waters, Publication No. 119, A. I. Johnson, Ed., pp. 15-29. Grenoble International Association of Hydrological Science. 

Sano, Y., Wakita, H. (1987) Island arc tectonics of New Zealand manifested in helium isotope ratios. Geochim. Cosmochim. Acta, 51, 1855-69. 

Stuart, F. M., Harrop, P. J., Knott, S., Turner, G. (1999) Laser extraction of helium isotopes from Antarctic micrometeorites Source of He and implications for the flux of extraterrestrial 3He to earth. Geochim. Cosmochim. Acta, 63, 2653-65. 

Tolstikhin, I. N. (1975) Helium isotopes in the earth s interior and in the atmosphere A degassing model of the earth. Earth Planet. Sci. Lett., 26, 88-96. 

Weiss, R. F. (1970b) Helium isotopic effect in solution in water and seawater. Science, 168, 247-8. 

Wiens, R., Lai, D., Rison, W., Wacker, J. F. (1994) Helium isotopic diffusion in natural diamonds. Geochim. Cosmochim. Acta, 58, 1747-57. 

Big Bang Of the very underabundant 3rd, 4th and 5 th elements (Li, Be, B), only 7Li is produced in significant quantities by the hot dense epoch of the early universe that we call the Big Bang. Its source is found among the last nuclear reactions that can occur between hydrogen and helium isotopes as the initial matter rapidly cools and thins out. The responsible nuclear reactions are a combination ... 

Proffitt M, Keto JW, Frommhold L (1980) Collision-induced spectra of the helium isotopes. Phys Rev Lett 45 1843-1846... 

Superfluid. Liquid helium (more precisely the 2He4 isotope) has a "lambda point" transition temperature of 2.17 K, below which it becomes a superfluid ("Helium-II"). This superfluid, or "quantum liquid," stays liquid down to 0 K, has zero viscosity, and has transport properties that are dominated by quantized vortices thus 2He4 never freezes at lbar. Above 25.2 bar the superfluid state ceases, and 2He4 can then freeze at 1K. The other natural helium isotope, 2He3, boils at 3.19 K and becomes a superfluid only below 0.002491 K. 

Bethe13 and Weizsacker14 established in the 1930s that the sun is a star fueled by the conversion of hydrogen isotopes into helium isotopes. 

Busemann H., Baur H., and Wieler R. (2001) Helium isotopic ratios in carbonaceous chondrites significant for the early solar nebula and circumstellar diamonds Lunar Planet. Sci. XXXII, 1598. Lunar and Planetary Institute, Houston (CD-ROM). 

Hanan B. and Graham D. (1996) Lead and helium isotope evidence from oceanic basalts for a common deep source of mantle plumes. Science 111, 991-995. 

---