Metal clusters and complexes represent model systems for studying heterogenous catalysis in the gas phase. These clusters and complexes emulate catalytic defect sites of bulk metals and exhibit molecular activation of adsorbed ligands, which can be investigated via their infrared spectra. Here, these techniques and their applications to CO_2 and OCS activation on Ho^+ , NO solvation of Group IX/X metal cations, and competitive ligand fixation to Au^+ are discussed. As well as this, new developments in instrumentation to produce and study cluster reactivity and vibrational mode selectivity are presented.
