The ion microprobe
is a mass spectrometry instrument that has been developed over the
past 30 years and which analyses secondary ions emitted by a sample
bombarded with a beam of primary ions. It enables high resolution
in situ analysis to be carried out and has many applications
in fields such as microelectronics, life sciences, medicine, and the
earth and astronomical sciences.
In the earth sciences, this technique has been applied to high resolution
study of complex samples either to assay trace elements in minerals
or to determine the isotopic compositions of many elements.
Along with these analytical developments, ion microprobes dedicated
to the earth sciences have been developed to produce high sensitivity
at very high mass resolution. Examples of applications include:
in
situ zircon dating, resulting in dating the oldest terrestrial
minerals, which are more than 4 billion years old;
intra-crystalline
isotopic heterogeneities, which have been observed in different
minerals to probe their history and evolution;
the
composition of mineral phases from deep in the earth, studied by
examining vitreous and crystalline inclusions;
isotopic
anomalies in refractory inclusions, studied to provide information
regarding nucleosynthesis in different star types;
studies
of the isotopic composition of the solar wind implanted in grains
of lunar dust, which have provided a better comprehension of the
function of the sun;
measuring
the isotopic composition of hydrogen in meteorites to determine
the origin of water in the protosolar nebula.
The
team at CNRS "Centre de recherches pétrographiques et
géochimiques" (CRPG, Petrographic and Geochemical Research
Centre), has been honing its skills with ion microprobes in the
above fields since the mid 1980s, primarily by in situ dating,
and measuring the isotopic composition of light elements applied
to environmental or paleoenvironmental problems and cosmochemistry.
