Photoemissions from hybrid states in metastable halogen-endofullerene molecules*

For the Cl@C$_{\mathrm{60}}$ endofullerene we consider the transfer of a C$_{\mathrm{60}} \quad \pi $ electron of $p$ angular character to the outer 3$p$ shell of confined Cl forming a metastable molecule Cl$^{\mathrm{-}}$@C$_{\mathrm{60}}^{\mathrm{+}}$. The ground state of this molecule is modeled in a spherical local density approximation (LDA) augmented by the Leeuwen and Baerends exchange-correlation functional [1] where the core of sixty C$^{\mathrm{4+}}$ ions is jelliumized [2]. A time-dependent LDA (TDLDA) method [3] is subsequently applied to calculate the dipole photoionization parameters of the molecule. Cross sections for the photoemission from levels hybridized between the C$_{\mathrm{60}}$ level containing the $p$ hole and the Cl$^{\mathrm{-}}$ 3$p$ level show the coherence between C$_{\mathrm{60}}$ plasmonic and atomic Coulomb dynamics. At higher energies, the mixing of confinement and cavity oscillations [4] determines the structures in the spectra. Calculations are also extended to similar hybrid levels of metastable Br$^{\mathrm{-}}$@C$_{\mathrm{60}}^{\mathrm{+}}$ and I$^{\mathrm{-}}$@C$_{\mathrm{60}}^{\mathrm{+}}$ Detailed comparison among the results provides deeper insights into the role of evolving halogen structures to influence the molecular photoionization. [1] R. van Leeuwen et al, Phys. Rev. A \textbf{49}, 2421 (1994); [2] M. E. Madjet et al., Phys. Rev. A \textbf{81}, 013202 (2010); [3] Choi et al., Phys. Rev. A \textbf{95}, 023404 (2017); [4] Potter et al., Phys. Rev. A \textbf{82}, 033201 (2010).