On confinement resonances in A@C60 photoionization: easy to observe?

TL;DR

This paper investigates why confinement resonances are often not observed in endohedral fullerenes' photoionization experiments, attributing the main cause to the finite cage thickness and atomic vibrations, and suggests conditions for their observability.

Contribution

The study identifies the primary reasons for the absence of confinement resonances in certain experiments and proposes Ne@C60 as a promising candidate for observing these effects.

Findings

Polarization effects are minimal, less than 20% near threshold.

Finite cage thickness significantly weakens confinement resonances.

Atomic vibrations and off-center positions further diminish resonance visibility.

Abstract

Possible reasons that confinement resonances are not observed in a recent photoionization experiment on the endohedral fullerene Ce@C82+ are explored. The effect of the polarization of the fullerene shell in response to the ionization of the endohedrally encaged atom A@Cn, termed the "shielding" effect, has been investigated and found to be relatively small; no more than a 20% effect near threshold, and much less at higher energies. It is argued that most likely, the absence of confinement resonances in Ce@C82+ is due primarily to the finite thickness of the carbon cage; the off-the-center position and thermal vibration of the encaged atom, discussed elsewhere, further weaken the resonances rendering them beyond the sensitivity of the experiment to detect, in this case. For other situations/endohedrals, the confinement resonances should well be observable, and Ne@C60 is suggested as an excellent candidate.