Photoionization of Atoms Encaged in Spherical Fullerenes

Abstract

Two semiempirical models for the photoionization of atoms A encaged in spherical single-walled fullerenes, both neutral Cn (n=60, 240 and 540) and charged C60±|z|, as well as in multiwalled fullerenes, termed fullerene onions, C60@C240 and C60@C240@C540 are detailed. The models are based on the approximation of a carbon cage Cn by a spherical attractive potential well of an adjustable radius Rn, thickness Δ and depth Un0. The first model, termed Δ-potential model, accounts for the finite thickness Δ of the cage. The second model, termed δ-potential model, simulates the cage with the help of the Dirac δ-potential, thereby viewing the cage as being infinitesimally thin. A side by a side comparison of results obtained within the two models is performed. The models’ predictabilities are evaluated. Predicted trends in the modification of photoionization spectra of encaged atoms as well as electron correlation and relativistic effects in the atoms, compared to the free atoms, obtained both at the independent particle (Hartree-Fock and Dirac Hartree-Fock) and multiparticle nonrelativistic random phase approximation with exchange (RPAE) and relativistic random phase approximation (RRPA) approximation levels, are reviewed.