Trapping and recording the collision- and photo-induced fragmentation patterns of multiply charged metal complexes in the gas phase

Abstract

A quadrupole ion trap has been interfaced with a pick-up cluster ion source and a quadrupole mass filter in order to combine the storage capabilities of the trap with the advantages of the pick-up technique for producing a wide variety of multiply charged metal–ligand complexes. Complexes produced using the pick-up technique are ionized by high energy electron impact before passing through a quadrupole mass filter. The mass-selected ions are transmitted by ion guide and injected into a quadrupole ion trap, where they are accumulated for up to 1000 ms and further isolated to remove any reaction/charge transfer fragments. Following collision-induced dissociation (CID) or photoexcitation, ions are ejected from the trap and mass analyzed. CID experiments show that certain dication complexes are very susceptible to the presence of background water in the trap, but that collisional activation can provide a mechanism for revealing stable metal/ligand combinations. The results from preliminary photoexcitation experiments in the form of infrared multi-photon dissociation (IRMPD) are discussed in terms of fragmentation patterns and processes induced by Coulomb explosion. The instrumentation and experimental parameters are presented here together with preliminary results on selected doubly charged complexes containing Cu 2+, Mg 2+ and Zn 2+. The apparatus is evaluated in terms of performance with regard to being able to provide sufficient ion signal to store and study the reactivity and spectroscopy of a wide range of multiply charged ions in the gas phase.