Probing many-electron resonances by the positronium formation spectroscopy

Positronium (Ps) formation studies of atoms, molecules, polymers, solids, liquids, surfaces/films, metal-organic-frameworks and embedded nanostructures are abundant. Our recent calculations [1,2] of Ps formation from fullerene molecules predicted target-geometry dependent diffraction resonances, which are of single-electron character and may be measured by available laboratory technology [3]. The current study, on the other hand, accesses the many-electron resonances, which are known to have been successfully described in photoelectron studies of atoms and fullerenes, by the Ps formation spectroscopy (PsFS). We model the ground state and the many-body linear response of the targets to the positron field by density functional methods [4] and the Ps formation is treated by the continuum distorted-wave final-state approximation [5]. The results, that will be presented, may motivate applications of PsFS to probe resonance signatures. [1] Hervieux \textit{et al.}, \textit{Phys. Rev. A} \textbf{95}, 020701 (R) (2017); [2] Hervieux \textit{et al}., \textit{Phys. Rev. A} \textbf{100}, 042701 (2019); [3] Hervieux \textit{et al}., \textit{Euro. Phys. J. D} \textbf{73}, 262 (2019); [4] Choi \textit{et al}., \textit{Phys. Rev. A} 95, 023404 (2017); [5] Fojon \textit{et al}., \textit{Phys. Rev. A} \textbf{54}, 4923 (1996).