The Mainz Cluster Trap -: Ion storage techniques at work in atomic cluster research

When cluster ions are stored by electromagnetic forces they are available in the gas phase for extended preparations and investigations. Over the last decade a Penning trap (Ion Cyclotron Resonance) apparatus has been constructed and further developed with respect to metal cluster research at the Institute of Physics at Mainz. It allows to capture and accumulate ion bunches injected from an external cluster source and to manipulate the ions: motion, i.e. select and center the clusters of interest. The interactions that have been investigated include those with inert and chemically reactive gases, photons and electrons. Multiple mass spectrometric steps such as fragment ion selection can be used to disentangle complex reactions or interfering reaction channels. A brief introduction into the principles of ion trapping and a.short overview of the history and experimental setup at Mainz are given. The advantages of ion storage with respect to extended preparation of the trapped cluster ensemble and with respect to extended reaction periods are exemplified by measurements of the collision induced dissociation of Ag-16(2+) and by time-resolved observation of the photodissociation of V-12(+). References are given both to the investigations performed at the Mainz Cluster Trap as well as to other experimental arrangements and measurements.