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Characterization of presolar silicate and oxide
grains using NanoSIMS and Auger spectroscopy.
Nguyen A., Stadermann F. J., Nittler L., and Alexander C.
M. O'D. (2008)
Lunar & Planet. Sci. 39, Abstract #2142.
ABSTRACT
Presolar silicates condensed in the outflows of red giant
stars and supernovae. In studying the isotopic compositions
of these grains, the nucleosynthetic processes that occur in
the parent stellar sources can be investigated. The chemical
compositions and mineralogies of the grains reflect the
physical conditions and compositions of the stellar
atmospheres during grain condensation. Presolar silicates
are typically less than 500 nm in diameter, making their
analysis experimentally challenging. The NanoSIMS ion
microprobe has become a powerful tool for analyzing the
isotopic compositions of presolar silicates. The Auger
nanoprobe is a good complementary technique for obtaining
chemical information because it achieves a high spatial
resolution (10s nm) and is non-destructive. Nine presolar
silicates identified in the ALHA 77307 carbonaceous
chondrite have previously been analyzed using Auger
spectroscopy. Here we describe new presolar silicates and
oxides identified in this meteorite, and the Auger results
of select grains.
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