[meteorite-list] WHERE ARE THE NANODIAMONDS IN PRIMITIVE METEORITES? PRELIMINARY TEM RESULTS
From: Shawn Alan <photophlow_at_meteoritecentral.com>
Date: Sun, 16 May 2010 12:31:25 -0700 (PDT) Message-ID: <332249.78816.qm_at_web113618.mail.gq1.yahoo.com> Hello Listers, Here is the second installment on the topic of nanodiamonds. WHERE ARE THE NANODIAMONDS IN PRIMITIVE METEORITES? PRELIMINARY TEM RESULTS BY: L.A.J. Garvie, Center for Meteorite Studies, Arizona State University, Tempe, Arizona 85287-1404, USA, lgarvie at asu.edu Introduction: Nanodiamonds are abundant in primitive meteorites. The work of [1] shows that most primitive meteorites have similar matrix normalized nanodiamond concentrations (within a factor of ca. 2.2), consistent with their location in the matrix. Huge numbers of meteoritic nanodiamonds occur in primitive meteorites, on the order of 3 x 1017 per gram of matrix. Nanodiamonds from primitive meteorites display a uniform size distribution and a mean diameter near 2 to 3 nm [2, 3]. They occur in the primitive members of all classes of chondrites [1, 4-7], with matrix-normalized values from ca. 700 to 1500 ppm [1, 6]. Despite their abundance in primitive meteorites, they may be scarce in fragile, C-rich IDPs thought to have originated form comets [8]. At least some nanodiamonds are believed to be pre-solar based on their excesses of the heavy isotopes of noble gases such as Xe and the trace elements Te and Pd [9-12]. These isotopes may have a supernova origin. Diamond dominates the residues of primitive meteorites after extreme acid dissolution and chemical oxidation. The dissolution removes the majority of minerals and sp2-bonded carbon leaving primarily diamond with a few percent of acid resistant minerals, e.g. [1]. Transmission electron microscopy (TEM) images of the residue show a m?lange of nanometersized diffracting domains. Despite many decades of research on nanodiamonds, relatively little is know about their location within the meteorite matrix. To begin to answer this question I have started to undertake work on locating nanodiamonds in the primitive meteorite matrices. Initial work is being done to find diamonds in the HF/HCl residue used to prepare the insoluble organic matter (IOM). The experience with finding diamonds in the IOM residue is then used to find diamonds in the raw, but disaggregated, meteorite matrix. Click on the link below for the whole article http://www.lpi.usra.edu/meetings/lpsc2010/pdf/1388.pdf Shawn Alan eBayshop http://shop.ebay.com/photophlow/m.html?_nkw=&_armrs=1&_from=&_ipg= Received on Sun 16 May 2010 03:31:25 PM PDT |
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