Atom-fullerene hybridization, giant enhancement and correlation confinement resonances in the photoionization of Xe@C$_{60}$

A detailed theoretical study of the subshell photoionization of Xe endohedrally confined in C$_{60}$ is presented. A powerful hybridization of the Xe $5s$ state with the bottom edge of C$_{60} \quad \pi $ band is found. Cross sections of these hybrid states exhibit rich structures and are radically different from the cross sections of free atomic or fullerene states [1]. The hybridization also affects the angular distribution asymmetry parameter of Xe $5p$ ionization near the Cooper minimum. The Xe $5p$ cross section, on the other hand, is greatly enhanced by borrowing considerable oscillator strength from the C$_{60}$ giant plasmon resonance [2]. Beyond the plasmon energy range the Xe subshell cross sections display confinement-induced oscillations in which, over the large $4d $shape resonance region, the dominant $4d $oscillations induce their ``clones'' in all degenerate weaker channels known as correlation confinement resonances. [1] H. S. Chakraborty et al., \textit{Phys. Rev.} A \textbf{79}, 061201(R) (2009); [2] M. E. Madjet et al., \textit{Phys. Rev.} A, in press.