  It is demonstrated in this Letter that the effect of the fullerene shell upon
atomic Giant resonance decisively depends upon energy of photoelectrons, by
which the resonance decay. According to the prediction in [1], the Giant
resonance in Xe is strongly modified in the endohedral Xe@C60 being transformed
from a single broad and powerful maximum in Xe into four quite narrow but with
almost the same total oscillator strength. On the contrary, the 4d Giant
resonances in ions Ce3+ (the electronic structure that Ce has, when stuffed
into fullerene), in Ce4+, and Eu are considered. In none of them the 4d Giant
resonance in endohedrals is affected essentially. This is because the decay of
the Giant resonances in these endohedrals proceeds by emission of fast
photoelectrons that are almost unaffected by the C60 shell. The results
obtained give at least qualitative explanation to the fact that recent
observation of 4d Giant resonance in Ce@C82+, where the Giant resonance was
observed as a maximum without noticeable structure.
