Reaction of aluminum cluster ions with oxygen and nitrous oxide: Energetics and dynamics of cluster oxidation

We report a study of the absolute cross sections, reaction threshold energies, and product branching ratios for interactions of aluminum cluster ions (Al+n, n=1–9) with O2 and N2O. Most of the reactions are observed to have collision energy thresholds which are attributed to activation barriers or bottlenecks. At collision energies above threshold, exoergic oxidation of the cluster ions occurs, and the resulting energy release causes extensive fragmentation to yield a variety of product ions. Comparison of threshold behavior for different product channels suggests that in addition to the dominant oxidation reactions, the clusters undergo Al abstraction, O2–Al+ exchange, and collision induced dissociation.