  The neutralization of low energy Na$^+$ and Li$^+$ ions scattered from Au
nanoclusters formed by deposition onto oxide surfaces decreases as the cluster
size increases. An explanation for this behavior is provided here, which is
based on the notion that the atoms in the clusters are not uniformly charged,
but that the edge atoms are positively charged while the center atoms are
nearly neutral. This leads to upward pointing dipoles at the edge atoms that
increase the neutralization probability of alkali ions scattered from those
atoms. As the clusters increase in size, the number of edge atoms relative to
the number of center atoms decreases, so that that the average neutralization
also decreases. Calculations employing this model are compared to experimental
data and indicate good agreement if the strengths of the dipoles at the edge
atoms are assumed to decrease with cluster size. This model also explains
differences in the neutralization probabilities of scattered Na$^+$ and Li$^+$.
