Trends in near-threshold photoionization of off-the-center endohedral atoms

Abstract

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 A-C{sub 60} molecules as a function of the displacement of the confined atom from the center of the C{sub 60} cage are demonstrated. Specific results for Li 1s from Li-C{sub 60}, and Ar 1s, 2s, and 3s from Ar-C{sub 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 C{sub 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 C{sub 60} molecule even affects the atom's photoelectron angular distribution when it is a significant distance away.