Xenon diamonds

Clayton DD (1989) Origin of heavy xenon in meteoritic diamonds. Astrophys J 340 613-619 Clayton DD, Dwek E, Woosley SE (1977a) Isotopic anomalies and proton irradiation in the early solar system. Astrophys J 214 300-315... 

Ott U (1993) Physical and isotopic properties of surviving interstellar carbon phases. In Protostars Planets III. Levy Hand Lunine JI (eds) University of Arizona Press, Tucson, p 883-902 Ott U (1996) Interstellar diamond xenon and timescales of supernova ejecta. Astrophys J 463 344-348 Ott U, Begemann F, Yang J, Epstein S (1988) S-process krypton of variable isotopic composition in the Murchison meteorite. Nature 332 700-702... 

The discovery happened by accident. Lewis and Anders were frustrated by their failure to find the carrier of anomalous xenon in carbonaceous chondrites. They decided to try an extreme treatment to see if they could dissolve the carrier. They treated a sample of the colloidal fraction of an Allende residue with the harshest chemical oxidant known, hot perchloric acid. The black residue turned white, and to their surprise, when they measured it, the anomalous xenon was still there The residue consisted entirely of carbon, and when they performed electron diffraction measurements on it, they found that it consisted of tiny (nanometer sized) diamonds. After a detailed characterization that included chemical, structural, and isotopic studies, they reported the discovery of presolar diamond in early 1987 (Lewis et al., 1987). The 23-year search for the carrier of CCFXe (Xe-HL) was over, and the study of presolar grains had begun. 

The characteristics of the presolar diamonds also change with the metamorphic grade of the host meteorite. F igure 5.15 shows the typical bimodal release of heavy noble gases (here illustrated by xenon) in Orgueil, an unheated chondrite. This pattern is compared to the xenon-release patterns of two ordinary chondrites that have experienced different degrees of mild metamorphism. The amount of low-temperature gas, labeled P3 for historical reasons, is a sensitive function of temperature. Its abundance correlates well with other indicators of... 

Diamonds are host to the HL component, named because it is enriched in both heavy and light isotopes of xenon (Fig. 10.10b). The high abundances of heavy isotopes suggest r-process nucleosynthesis, whereas the abundant light isotopes suggest the -process. Both the r- and -processes occur in supemovae. However, it is not obvious why products of the two nucleosynthetic processes would be coupled, and this remains a subject of current research. Diamonds also contain other, less-anomalous noble gas components... 

Fig. 3.13. Total (tot, upper solid line) and elastic (el, lower solid line) cross sections for positron-noble gas scattering near the positronium formation threshold from the R-matrix analysis of Moxom et al. (1994). Graphs (a)-(e) correspond to helium through to xenon. The data points shown are total cross section measurements from the literature (see Chapter 2 and Moxom et al., 1994, for details) except for the solid diamonds for helium, which are the

Clayton, D. D. 1989 Origin of heavy xenon in meteoritic diamonds. Astrophys. J. 340, 613-619. 

Lewis, R. S. Anders, E. 1989 Xenon HL in diamonds from the Allende meteorite x-composite nature. Lunar. Planet. Sci. XIX, 679-680. 

Fayizrakhmanov I.A., Bazarov V.V., Stepanov A.L., Khayibulin I.B. Modification of nanostructure of diamond-like films by xenon bombardment. Fiz. Tech. Polupr. (in Russian) 2003 37 748-752. 

Figure 1 1/Ti vs. T for I2 in xenon at a density of p = 3.0 g/cm3. The open diamonds are the experimental points, and the solid circles (with connecting lines) are from theory.

Fig. 2.17. Schematic layout of a microscope spectrophotometer system used to measure polarized absorption spectra of very small mineral crystals. The computer-operated, single-beam instrument shown here comprises a polarizing microscope equipped with a stabilized light source (xenon arc lamp or tungsten lamp cover the range 250-2000 nm), a modulator that chops the light beam with a frequency of 50 Hz (the amplifier for the photodetector signals is modulated with the same phase and frequency), and a Zeiss prism double monochromator. Single crystals as small as 10 ji.m diameter may be measured with this system. A diamond-windowed high-pressure cell can be readily mounted on the microscope scanning table for spectral measurements at very high pressures (after Burns, 1985, reproduced with the publisher s permission).

Ott U. (1996) Interstellar diamond xenon and timescales of supernova ejecta. Astrophys. J. 463, 344-348. 

Fibrous diamonds show positively correlated excesses of Xe and Xe of up to 10% relative to atmospheric values, similar to the systematics shown by MORE (Figure 59). These data provide some of the best-determined mantle xenon isotope measurements. The xenon isotope excesses are attributed to decay of extinct and... 

Figure 10.1 Vapor-liquid coexistence curves for neon (open squares), argon (filled circles), krypton (filled squares), xenon (open down-triangles), methane (open circles), nitrogen (open diamonds), and oxygen (open up-triangles). Data taken from the NIST Chemistry Webbook http //webbook.nist.gov.

Kuroda PK (1960) Nnclear fission in the early history of the earth. Nature 187 36-40 Lewis RS (1975) Rare gases in separated whitlockite from the St. Severin chondrite Xenon and krypton from fission of extinct " " Pu. Geochim Cosmochim Acta 39 417-432 Lewis RS, Ming T, Wacker JF, Steele IM (1987) Interstellar diamonds in meteorites. Nature 326 160-162 Lipschutz ME, Gaffey ME, Pellas P (1989) Meteorite parent bodies nature, number, size and relation to present-day asteroids. In Asteroids 11. Binzel RP, Gehrels T, Matthews MS (eds) University of Arizona, Tucson, p 740-788... 

Ozima M, Zashu S (1988) Solar-type Ne in Zaire cubic diamonds. Geochim Cosmochim Acta 52 19-25 Ozima M, Podosek FA, Igarashi G (1985) Terrestrial xenon isotope constraints on the early history of the Earth. Nature 315 471-474... 

Ott U (1995) A new approach to the origin of Xenon-HL. Meteoritics 30 559-560 Ott U (1996) interstellar diamond xenon and timescale of supernova ejecta. Astrophys J 463 344-348 Oxbmgh ER, ONions RK (1987) Hehum loss, tectonics, and the terrestrial heat budget. Science 237 1583-1587... 

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