Trends in near-threshold photoionization of off-the-center endohedral atoms
Annotatsiya
Calculations of the photoelectron angular distribution from atoms confined in a fullerene cage have been performed using a recently developed theory of inner-shell near-threshold molecular photoionization. Trends uncovered in the modification of near-threshold photoelectron angular distribution of the $\mathrm{A}@{\mathrm{C}}_{60}$ molecules as a function of the displacement of the confined atom from the center of the ${\mathrm{C}}_{60}$ cage are demonstrated. Specific results for Li $1s$ from $\mathrm{Li}@{\mathrm{C}}_{60},$ and Ar $1s,$ $2s,$ and $3s$ from $\mathrm{Ar}@{\mathrm{C}}_{60}$ molecules are presented. In addition, the situation where the encapsulated atom lies in the vicinity of the center of one of the carbon hexagons of ${\mathrm{C}}_{60}$ and also when it is displaced beyond the fullerene cage, has been studied. It has been found that the photoelectron spectra are extremely sensitive, both qualitatively and quantitatively, to even a small displacement of the confined atom from the center of the cage. The existence of the ${\mathrm{C}}_{60}$ molecule even affects the atom's photoelectron angular distribution when it is a significant distance away.