Heidelberg 2015 – wissenschaftliches Programm

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A: Fachverband Atomphysik

A 11: Poster: Atomic clusters (with MO)

A 11.2: Poster

Montag, 23. März 2015, 17:00–19:00, C/Foyer

Investigation of a ring ion trap for the produdtion of multiply-charged cluster anions — •Stefan Knauer, Gerrit Marx, and Lutz Schweikhard — Institut für Physik, Universität Greifswald, Felix-Hausdorff-Str. 6, 17489 Greifswald

A multipole ring trap was built for systematic studies of cluster anions. The Coulomb barrier and electron binding energies of multiply-charged metal clusters are experimentally mostly uninvestigated. Because polyanionc metal-clusters do not exist in nature, they have to be produced in laboratories by cluster electron collision. This can be achieved by combinations of cluster sources and ion traps [1]. A method to investigate the Coulomb barrier is the production of negative charge states with precise electron energies. To do so, one needs a field free region for the cluster-electron interaction where, simultaneously, the cluster ions are trapped. For this purpose a multipole ring electrode trap [2] was built. The experiment consists of a magnetron sputter source [3], a quadrupole bender, the ring electrode trap and a section for time-of-flight mass spectrometry (ToF MS). The sputter source is used to produce singly-charged negative metal clusters, which are guided into the trap. Cooled cluster ions can gain multiple charge states by cluster-electron collisions. For those collisions the cluster and electrons have to interact in a field free region, which a ring-electrode trap provides. In a next step, the experiment should provide defined charge states for laser interaction experiments. The contribution will discuss the principle and design of the ring electrode trap, preliminaryion-confinement tests and corresponding mass spectra.