Storage Of Protonated Water Clusters In A Biplanar Multipole Rf Trap

We present the storage properties of protonated water clusters H+(H2O)(n) (n = 1-4) in an improved biplanar ion trap. The design is based on our recently reported realization of a biplanar multipole radiofrequency (rf) ion trap (Debatin et al 2008 Phys. Rev. A 77 033422). The new experimental setup is composed of the ion trap in tandem time-of-flight configuration for mass-selective ion loading and mass-selective detection of stored ions. Special attention is paid to the supersonic discharge cluster source and our improved realization of a biplanar multipole ion trap with a simplified electrode layout. The source performance is presented and mass-selective loading into our trap is demonstrated with H+(H2O)(n) clusters. We achieve stable trapping of H+(H2O)(n) clusters (n = 1-4) with storage lifetimes of 3-12 s, which is comparable to former achievements with stable atomic Ar+ ions in the first trap generation. Collision-induced cluster dissociation during the loading process is observed.