Investigating cooperative effects in small cobalt and cobalt-nickel alloy clusters with attached ethanol.

Small cationic cobalt, and cobalt-nickel alloy clusters with ethanol attached are generated in a pulsed molecular beam experiment using a laser ablation source. While the metal center is successively varied with respect to size and composition, a full-size study of these transition metal clusters is possible. The clusters are investigated IR photodissociation spectroscopy in the region of OH- and CH-stretching vibrations. The results are compared with theoretical data obtained from DFT calculations. Both frequency shifts and structural changes according to cluster size and composition are identified and discussed in detail, also with respect to cooperative effects. Trimeric metal clusters with an uneven number of nickel atoms show evidence for C-O cleavage of the ethanol molecule. This result is elucidated by further calculations concerning the reactivity, charge and energetic distributions.