Correlation confinement resonances in photoionization of endohedral atoms:: Xe@C60

A new type of confinement resonance, termed a correlation confinement resonance, occurring in the photoionization of an atom A encapsulated inside the hollow cage of C-60, A@C-60, is found and interpreted in this paper. It is multielectron in nature and is induced in the photoionization of an outer shell of the confined atom by 'ordinary' confinement resonances in photoionization amplitudes from deeper subshells as a result of interchannel coupling. The effect is illustrated by calculations of the 5s photoionization cross section of endohedral Xe, Xe@C-60, in the region of the 4d giant resonance exhibiting ordinary confinement resonances.