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Schlagwörter:
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Zusammenfassung:
In this work, momentum imaging experiments have been conducted for the electron
impact excitation of metastable states in noble gases and for dissociative electron
attachment (DEA) in polyatomic molecules. For the electron impact excitation
study a new experimental technique has been developed which is able to measure
the scattering angle distribution of the electrons by detection of the momentum
transfer to the atoms. Momentum transfer images have been recorded for helium
and neon at xed electron impact energy close to the excitation threshold and good
agreement with current R-matrix theory calculations was found.
A new momentum imaging apparatus for negative ions has been built for the purpose
of studying DEA in biologically relevant molecules. During this work, DEA
was investigated in the molecules ammonia, water, formic acid, furan, pyridine and
in two chloro
uorocarbons. Furthermore, the change of DEA resonance energies
when molecules form clusters compared to monomers was investigated in ammonia
and formic acid. The experimental results of most studied molecules could be compared
to recent theoretical calculations and they support further development in the
theoretical description of DEA. The new apparatus built in this work also delivered
a superior momentum resolution compared to existing setups. This allows the
momentum imaging of heavier fragments and fragments with lower kinetic energy.
