Atomic giant resonances in clusters

Atomic giant resonances in clusters were observed by Brechignac et al [696] for clusters of Sb. Since the spectrum of the corresponding free atom was not available, the universal curve deduced from the uncertainty principle (see section 5.16) was used for analysis. The resulting point (see fig. 12.13) shows that the observed resonance fits closely onto the line for free atoms. 

The resonances exhibit interesting variations as a function of atomic number, the origin of which is unexplained. As can be seen in fig. 12.14, their intensity relative to the rest of the spectrum fluctuates strongly, with the giant resonance actually disappearing from view for n = 8, 12, 16, etc atoms in the cluster. This behaviour seems in some way to be related to the fact that Sb clusters tend to be made up from smaller groups of four atoms stuck together. 

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