the emitted particles originate predominantly from the uppermost
one or two monolayers the information obtained from SIMS
data refers to the surface. The dimensions of the collision
cascade are rather small (a few nm in diameter), therefore
the lateral resolution is determined by the provision of
finely focussed primary ion beam.
destructive in nature because particles are removed from
the surface. This can be used to erode the target in a controlled
manner and obtain information on the in-depth distribution
of elements. This dynamic SIMS mode is widely applied to
analyze thin films, layer structures and dopant profiles.
In order to receive chemical information on the original
undamaged surface, the primary ion dose density must be
kept low enough (< 1013 cm-2) to
prevent a surface area from being hit more than once. This
so-called static SIMS mode is used for the characterisation
of molecular surfaces.
stems a technique using analysis of the emitted neutral
particles. Post-Ionisation of these particles by electrons,
plasma or photons allows to use the same types of analyzers
for mass analysis of species originally emitted as neutrals.
This technique is called Secondary Neutral Mass Spectrometry,
SNMS. One of the most efficient ways to ionise the emitted
neutrals is Laser Post-Ionisation (Laser-SNMS). The fraction
of the neutrals detected in this way can be as high as 10
%, and the technique is attractive for the analysis of extremely