Communications: Investigation of the superatomic character of Al13 via its interaction with sulfur atoms.

We investigated Al(n)S(-) (n=3-15) and Al(n)S(2)(-) (n=7-15) clusters with mass spectrometry and photoelectron spectroscopy. We found that Al(13) is relatively robust when it reacts with sulfur atoms, indicating that it has some superatomic character. However, Al(13) cannot be simply considered as a superatom when it interacts with sulfur due to the following reasons: Al(13)'s icosahedral structure has been distorted slightly by sulfur atoms; the vertical detachment energies and adiabatic detachment energies of Al(13)S(-) and Al(13)S(2)(-) clusters are not significantly different from those of their neighboring clusters; and the charge distributions in Al(13)S(-) and Al(13)S(2)(-) do not necessarily associate with superatomic behavior of Al(13).