» Astrolab » Research 

AIACS: an Advanced Ion Atom Collision Setup for the CSR

We are currently developing a neutral beamline for the Cryogenic Storage Ring at MPIK. With this setup we will be able to study reactions between neutral atoms (H,D,C,O) and cold molecular ions under controlled conditions over a wide range of collision energies. One of the straight sections of the storage ring will be used for the injection of molecular ions and interactions with neutral beams. The neutral atom beam will be produced by photodetachment using a strong infrared laser. The ions and neutrals will be superimposed only in the center of the straight section and the charged  reaction products will be separated from the circulating ion beam by the first  electrostatic deflector behind the overlap region. The reaction products will be detected by a dedicated single particle detector.

Coulomb Explosion Imaging of Molecular Ions

We use a unique foil-induced Coulomb Explosion Imaging approach to take "snapshots" of the structure of molecular ions. The structure of molecular ions, either from the TSR storage ring or directly from the accelerators of the institute, can be analyzed by passing them through very thin foils, where they lose their binding electrons on a sub-femtosecond time scale. Event-by-event imaging of the fragmentation products reveals the nuclear wave function of the molecular ions. Recent experiments have been performed on the negative hydrogen molecules (in particular H2- and D2-), which are transient species living shorter than a millisecond and become relatively stable only if they strongly rotate around their axis. 

Furthermore, we have used the CEI method to take the first images of enantio-selected chiral molecules in the gas phase.

Laser Spectroscopy and Molecular Reaction Dynamics in a Radiofrequency Ion trap

Molecular ions play an important role in many fields and environments, from combustion, Earth's atmosphere to astronomical plasmas and cold interstellar clouds. Experiments with cold molecular ions are notoriously difficult since (1) typical densities are much lower than for neutral species, (2) the ionization process usually results in widespread internal excitation (vibrations and rotations).

To deal with these issues, it is advantageous to accumulate molecular ions in ion traps and cool them actively in collisions with a suitable buffer gas.  We use a cryogenic 22-pole ion trap to prepare and study cold molecular ions down to temperatures of 10K. For these experiments our focus has been on various reaction dynamics and spectroscopic studies of the fundamental triatomic hydrogen ion H3+.   


Dr. Holger Kreckel

Research Group Leader
Max-Planck-Institut für Kernphysik
Tel.: +49 6221 516 517