Infrared studies of astronomically relevant metallic clusters and their interactions with simple molecules

The work presented in this thesis aims at: a) providing fundamental knowledge on the interactions of simple ligands with metal clusters relevant to astronomical and (bio-) catalytical processes, b) providing a benchmark that can be used to test current and future DFT methods developed to study these or related systems. To this purpose, we studied astronomically relevant metal clusters (Fe, FeS, AlO) as well as metal clusters that are catalytically important (MnO and Co) using IRMPD techniques. Clusters are formed through laser ablation of solid precursor materials and brought into a molecular beam environment. Mass-selected IR action spectra are recorded by irradiating the clusters using IR light from FELIX. Experimental spectra are then compared with DFT prediction which enables us to determine the structure of the selected cluster and its binding interactions with ligands.
We observed in these studies that water associated with different kinds of clusters may dissociate at ambient temperature. The levels to which this dissociation occurs is of great importance to catalytic and astrochemical models. On the catalytic side, an impressive example of the influence of cluster size is found for iron clusters where we conclude that activation of water is very much dependent on the size of the cluster. On manganese oxide clusters, water is shown to dissociate, which is a prerequisite for water splitting by such clusters. In the astronomical context, this means that metal particles may create an environment that catalysis particular reactions, which in turn can lead to the formation of more complex molecules even on the surface of the clusters.