Reactions of bare aluminum cluster ions

Absolute cross sections for reaction of aluminum atomic, dimer and trimer ions with oxygen, water and ethylene are reported. For all three reactions the dimer ion is by far the most reactive at low collision energies. The atomic ion is four to ten times less reactive and the trimer is non-reactive within our sensitivity. At higher collision energies the dimer reactivity drops and in some cases the atomic and trimer ion reactivities increase. Extensive fragmentation of the cluster ions is observed at collision energies above 3.0 eV.