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

When cluster ions are stored by electromagnetic forces they are available i n the gas phase for extended preparations and investigations. Over the last decade a Penning trap (Ion Cyclotron Resonance) apparatus has been constru cted and further developed with respect to metal cluster research at the In stitute of Physics at Mainz. It allows to capture and accumulate ion bunche s injected from an external cluster source and to manipulate the ions: moti on, i.e. select and center the clusters of interest. The interactions that have been investigated include those with inert and chemically reactive gas es, photons and electrons. Multiple mass spectrometric steps such as fragme nt ion selection can be used to disentangle complex reactions or interferin g reaction channels. A brief introduction into the principles of ion trappi ng and a.short overview of the history and experimental setup at Mainz are given. The advantages of ion storage with respect to extended preparation o f the trapped cluster ensemble and with respect to extended reaction period s 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 measurement s.