Photoabsorption spectra of Xe atoms encapsulated inside fullerenes

Abstract

The photoabsorption spectra of Xe atoms encapsulated inside the C₁₈₀ and C₂₄₀ have been investigated using the time-dependent density-functional theory (TDDFT) and compared with the result of our short range spherical well. The calculations are performed in the energy region of the Xe 4d giant resonance and assumed the central location of the Xe atom inside the fullerenes. The Xe-C₁₈₀ and Xe-C₂₄₀ binding energies along the high symmetry direction, the z axis have been evaluated as well. The obtained curves show the possibility of other Xe positions. The main features of the confinement resonances for the Xe atoms in the center of the C₁₈₀ and C₂₄₀ may be estimated by the formula E(eV) = 67.55 + (12.25n/2r)², where r is the radius in Å of the fullerene, n is the integer number 2, 3, 4, 5, ..., and E (eV) is the location of a confinement peak. The calculations indicate that if the radius of a fullerene equals an integer (≥2) × the half wave length of the photoelectron, then at this photon energy we may observe a confinement peak. The photoabsorption spectra of Xe atoms encaged in the center of the C₅₈, C₅₆ and C₅₄ have also been studied. The results demonstrate that, except for the Xe atom inside C₅₈, which has similar confinement resonances as those of the Xe atom inside C₆₀, the Xe atoms inside C₅₄ and C₅₆ have completely different spectra. It is concluded that the quantum confinement resonances will be destroyed if the shape of the fullerene is deformed significantly from a sphere.

Graphical abstract