Photoionization cross section and time-delay of atoms confined in C$_{\mathrm{240}}$ versus C$_{\mathrm{60}}$.

We investigate the effects of confinement and electron correlation on the photoemissions of noble gas atoms sequestered endohedrally in C$_{\mathrm{240}}$ and compared with the corresponding results of C$_{\mathrm{60}}$ confinement. The time-dependent local density approximation (TDLDA) method [1] with Leeuwen and Baerends (LB94) exchange-correlation functional is employed in the calculation. The core of 240 C$^{\mathrm{4+}}$ ions is jelliumized to ignore the carbon $K$-shell structures. We compute subshell cross sections and angle-integrated Wigner-Smith (WS) time-delays [2] for atomic-type as well as atom-fullerene hybrid-type levels. We examine the size effects of the molecular cage on the plasmonically enhanced [3] strength of the atomic ionization. Furthermore, the behavior of photoemission WS time delays in attoseconds, induced by this enhancement as well as by the confinement-modified atomic Cooper minima [4], as a function of fullerene size and electronic structure, is scrutinized in detailed. [1] Choi \textit{et al.,} PRA \textbf{95}, 023404 (2017) [2] Dixit \textit{et al}., PRL \textbf{111}, 203003 (2013) [3] Madjet \textit{et al.}, PRL \textbf{99}, 243003 (2007) [4] Magrakvelidze \textit{et al}., PRA\textbf{ 91}, 053407 (2015).