Photoionization of multishell fullerenes studied by ab initio and model approaches*

Abstract

Abstract: Photoionization of two buckyonions, C60@C240 and C20@C60, is investigated by means of time-dependentdensity-functional theory (TDDFT). The TDDFT-based photoabsorption spectrum ofC60@C240, calculated in a broad photon energy range, resemblesthe sum of spectra of the two isolated fullerenes, thus illustrating the absence of strongplasmonic coupling between the fullerenes which was proposed earlier. The calculatedspectrum of the smaller buckyonion, C20@C60, differs significantly from the sum of the crosssections of the individual fullerenes because of strong geometrical distortion of thesystem. The contribution of collective electron excitations arising in individualfullerenes is evaluated by means of plasmon resonance approximation (PRA). An extension ofthe PRA formalism is presented, which allows for the study of collective electronexcitations in multishell fullerenes under photon impact. An advanced analysis ofphotoionization of buckyonions, performed using modern computational and analyticalapproaches, provides valuable information on the response of complex molecular systems tothe external electromagnetic field. Graphical abstract: [Figure not available: see fulltext.]