Negative ion photodetachment spectroscopy of the Al3O2, Al3O3, Al4Ox, Al5Ox(x = 3–5), Al6O5, and Al7O5clusters

Abstract

The Al3O2, Al3O3, Al4Ox, Al5Ox (x = 3–5), Al6O5, and Al7O5 clusters are studied using negative ion photoelectron spectroscopy. At 266 nm (4.661 eV) laser photodetachment wavelength the spectra of Al3O2 and Al3O3 present vibrationally resolved features. They show three electronic transitions, due to two different isomers. From Franck–Condon simulations of the Al3O2 and Al3O3 photoelectron spectra, several vibrational frequencies together with the normal coordinate changes were derived. We obtained approximate electron affinities for Al3O2 and Al3O3 using the Gaussian 2 model, and calculated isomerization energies for both the anionic and neutral geometries and the experimental adiabatic detachment energies (ADE) of bands X′ and X. The larger aluminum oxide clusters present several structureless bands which likely also result from multiple isomers. The ADEs for the larger clusters increase with size within a cluster series, with the exception of Al5O5.