Abstract
We have recently developed a computational methodology to separate the
effects of size, composition, symmetry and fluxionality in explaining
the experimental photoelectron spectra of mixed-metal clusters. This
methodology was successfully applied first in explaining the observed
differences between the spectra of
Al13- and
Al12Ni- and more recently to explain
the measured spectra of AlnMo-,
n=3-5,7 clusters. The combination of our approach and new synthesis
techniques can be used to prepare cluster based materials with tunable
properties. In this work we use the methodology to predict the spectrum
of Al6Mo-. This system was chosen
because its neutral counterpart is a perfect octahedron and it is
distorted to a D3d symmetry and was not observed in the
recent experiments. This high symmetry cluster bridges the less
symmetric Al5Mo- and
Al7Mo-structures. The measured spectra
of Al5Mo- has well defined peaks,
while that of Al7Mo-does not. This can
be explained by the fluxionality of
Al7Mo-, as at least 6 different
structures lie within the range that can be reached by thermal effects.
We predict that Al6Mo- has well
defined peaks, but some broadening is expected as there are two
low-lying isomers, one of D3d and the second of
D3h symmetry that are only 0.052 eV apart.