The DESIREE Electrospray Ionization stand-alone beam-line serves as a test bench for complex ion-beam production and for ion-beam bunching and buffer-gas cooling. Bunching and cooling is needed for injection of ions in the DESIREE rings when the beams are weak and/or when the ions only cool very slowly. through spontaneous relaxation. ElectroSpray Ionization (ESI) offers a soft ionization method and thus enables production of fragile molecular ions. Such molecular ions include e.g. biomolecules and Polyclic Aromatic Hydrocarbons (PAHs). For accumulation we use a radio-frequency octupole ion trap (8-pole trap). The bunched ions are then mass-selected before injection in a cryogenically cooled ring-electrode trap, where any internal excitations are quenched in collisions with cold (4-5 K) He buffer gas. The setup is fully operational and it is now successfully used to serve single-pass collisions experiments. We have shown that we indeed can produce and handle faint beams from an ESI source and that we can accumulate and cool sufficiently intense pulses of them (about one million ions per pulse) for DESIREE merged-beams experiments. We are currently in the process of setting up a similar ESI system on the 100 kV DESIREE injector platform and we plan to install a third ESI system at the 25 kV injector as well. This will allow studies of interactions between pairs of complex ions in DESIREE.
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