by
Nicole Haag(Stockholm University, Department of Physics)
→
Europe/Stockholm
FB55
FB55
Description
This thesis deals with fragmentation of complex molecular ions, especially biomolecules, in gas
phase collision experiments. The aim is to investigate the relations between energy deposition and
fragmentation and to shed light on the mechanisms behind energy and charge transfer processes in
collisions involving the building blocks of life. Further, the question how a solvent environment
influences the dissociation behavior is elucidated. In the first part of the thesis, results from different
collision experiments with biomolecular ions are presented, focusing on electron capture induced
dissociation of hydrated nucleotides and small peptides. The investigated processes may be relevant
for the understanding of radiation damage and the optimization of sequencing methods used in
protein research. Our results clearly demonstrate that effects due to surrounding solvent molecules
are substantial. While the dissipation of internal energy by evaporation of the loosely bound solvent
molecules may protect the biomolecule, the influence which this environment has on the electronic
structure may lead to an enhancement or suppression of certain dissociation channels. The second
part of the thesis focuses on recent instrumental developments. Here, the aim was to optimize and
complement the techniques used in the experiments above and to have versatile tools available for
different kinds of gas phase collision studies involving complex molecular ions. Therefore, we have
constructed an electrospray ion source platform for the preparation of intense beams, with options
of accumulation and cooling of mass selected ions, allowing for a large variety of experiments.
This device is also intended to serve as an ion source for the new storage ring facility DESIREE
(DoubleElectroStatic Ion Ring ExpEriment), which is currently under construction at Stockholm
University. In these unique storage rings, oppositely charged ions may interact at very low relative
velocities in a cryogenically cooled and ultrahigh vacuum environment.