Nuclear Reaction Analysis
We use Nuclear Reaction Analysis (NRA)
for depth profiling of polymer samples. The basic principle of the NRA is as follows:
An incoming ion beam enters through the surface of a thin film and loses energy
while penetrating the film - in the range of the energies we use, this stopping
process is mainly due to interaction of the beam with atomic electron shells (electronic
stopping). In a certain depth the incoming particle can undergo a nuclear reaction
with atoms of the film. The energy of the reaction products is a function of the
energy of the incoming ions. It is possible in this way to calculate from the
energy distribution of the reaction products the depth distribution of the atoms
that react with the incoming ions. We use in our setup the following nuclear reaction:
As nuclear reactions are isotope specific we can use this analysis for binary
blends of polymers, where one of the polymers is labeled with deuterium. The NRA
gives us the depth distribution of the deuterium atoms and so of the labeled polymers.
Here you see a typical depth profile of a phase separated polymer film - with
a rich and a poor phase of the deuterated polymer.
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