Photoionization of atoms stuffed inside a two-shell fullerene

TL;DR

This paper develops a theoretical framework for analyzing the photoionization process of atoms encapsulated inside a two-shell fullerene, accounting for shell effects, polarization, and interactions, with specific examples for argon and xenon endohedrals.

Contribution

It introduces formulas for cross-sections and anisotropy parameters considering two-shell fullerene effects, including polarization and shell interactions, using the RPA method.

Findings

New peculiarities in photoionization of endohedral fullerenes identified.

Theoretical predictions for specific endohedral atoms provided.

Effects of shell polarization and interactions quantified.

Abstract

The photoionization of a two-shell endohedral A@CN1@CN2 is considered. Formulas are presented for cross-sections and angular anisotropy parameters, both dipole and non-dipole. The effect of the fullerenes shell upon photoelectron from atom A is taken into account substituting the action of the fullerene by two zero-thickness "bubble potential". The fullerenes shells polarization is included assuming that the radius of the outer shell R2 is much bigger than the inner R1 and both much exceeds the atomic radius r. This permits to express the effect via CN1,N2 polarizabilities, which are connected to their photoionization cross-sections. The interaction between shells CN1 and CN2 is taken into account in the Random Phase Approximation (RPA). The effect of photoelectron scattering by both "bubble potentials" is included in the lowest order and in the RPA frame. As concrete examples, two endohedrals Ar@C60@C240 and Xe@C60@C240 are considered. In the first case we consider 3p and 3s, while in the second 5p, 5s and 4d subshells. A whole variety of new peculiarities are found that deserve experimental verification.