Structural Characterization of Unprecedented Al14O- and Al15O2-: Photoelectron Spectroscopy and Density Functional Calculations

New aluminum oxide clusters Al14O- and Al15O2- were observed unprecedentedly in the gas-phase reaction of Al-n(-) and O-2. Photoelectron spectroscopic measurements and density functional calculations indicated that Al14O- and Al15O2- are composed of an icosahedral Al-13 moiety bonded by one and two OAl unit(s), respectively. The preferential formation of Al14O- and Al15O2- is explained in terms of the high stability associated with the Al-13 moiety and efficient collisional trapping as intermediates of oxidative etching reactions.