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Isotopic and elemental studies at a 50 nm scale
with the NanoSIMS
Stadermann F. J. (2002) 12th annual VM Goldschmidt
Conference (invited keynote lecture)
Geochimica et Cosmochimica Acta, 66 (15A, Special
Supplement), A734.
This
text as PDF file.
The NanoSIMS is a revolutionary new type of ion
microprobe with a wide range of applications in areas like
biology, material science and geochemistry. The first
commercial NanoSIMS was installed in St. Louis in December
2000 and has since been used for a large number of
microanalytical studies of extraterrestrial materials that
would not have been possible with any other instrument. The
most important features of the NanoSIMS are a primary beam
diameter at the sample of less than 50 nm, a very high
secondary ion transmission - even at high mass resolution -
and the capability of measuring several secondary ion
signals simultaneously.
One of the most fascinating aspects of the work with the
NanoSIMS is that it can be used as a complement to the
transmission electron microscope (TEM). Previous generations
of ion microprobes could determine the isotopic compositions
of micrometer-sized (and larger) sample components, but it
was not possible to determine the mineralogical context of
the observed features due to differences in size scales and
sample mounting requirements. With the NanoSIMS it is not
only possible to measure isotopes at a spatial resolution
that comes close to that of the TEM, but it is possible to
do so directly in TEM sections, without any modifications to
the sample itself. A sample can first be characterized in
the TEM and then be transferred to the NanoSIMS for raster
imaging SIMS analysis. It is thus possible to directly
correlate isotopic and mineralogical information of a sample
and its sub-components on a scale of 50 nm. This combination
of two powerful microanalytical techniques may become one of
the strongest tools for the investigation of
extraterrestrial materials.
References:
See http://presolar.wustl.edu/nanosims/
for more detailed information about the St. Louis
NanoSIMS.
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