Michael Lembach

• This thesis is separated into seven distinct research projects on mono and multinuclear transition metal complexes as trapped ions in gas phase, as well as one chapter on focusing on the development of a new ion source to enable access to catalytic processes via coadsorption. ElectroSpray Ionization (ESI) transfers ions from solution to gas phase for mass spectrometric investigations, allowing a broad variety of experimental methods to obtain fundamental insights into the molecular properties of isolated complexes devoid of solvent, crystal lattice, bulk, or supporting surface effects. Collision Induced Dissociation (CID) researches molecular fragmentation mechanisms and their relative gas phase stabilities at room temperature. Laser experiments such as InfraRed (Multiple) Photon dissociation and Ultraviolet Photon dissociation offer information on the bonding motifs, resulting in molecular structures and their electronic ground states. When quantum chemical calculations utilizing Density Functional Theory (DFT) and Time Dependent Density Functional Theory (TD-DFT) are combined with monitored spectra, a better and deeper understanding of the structural properties and electronics of transition metal complexes is possible. X-ray magnetic circular dichroism (XMCD) is a technique that analyzes the magnetic properties of isolated and trapped ions at cryogenic temperatures inside an externally applied magnetic field using high brilliant polarized X-ray photons in conjunction with a mass spectrometer. The element selective technique, combined with sum analysis, allows for the decomposition of the total magnetic moments in their spin and orbital magnetic moments in various metal centers. A determination of the magnetic couplings between distinct metal centers in multinuclear complexes is possible via Broken symmetry approach in combination with X-ray Magnetic Circular Dichroism (XMCD).