Hydrodynamic model of the collective electron resonances in C60 fullerene

TL;DR

This paper models the collective electron resonances in C60 fullerene using a hydrodynamic approach, revealing that the main absorption features are due to volume plasmons with frequencies exceeding the plasma frequency, aligning well with experimental data.

Contribution

It introduces a hydrodynamic model accounting for spatial dispersion in C60, providing new insights into the nature of its plasmons and their contribution to absorption spectra.

Findings

Main absorption is due to volume plasmons with frequencies above plasma frequency.

Both low and high surface plasmons become volume plasmons under C60 parameters.

Model's absorption spectrum agrees well with experimental measurements.

Abstract

The polarization-response spectrum of the fullerene C60 modeled as a homogeneous spherical plasma shell is calculated in the framework of the hydrodynamic approach allowing for the spatial dispersion caused by the Fermi-distributed valence electrons. The dipole eigenoscillations spectrum of the shell is found to contain a series of plasmons distinguished by the frequency and the radial structure. The first two of them (whose structures for C60 is the subject of discussion up to now) pass to the lower and higher surface plasmons of the plasma shell if its thickness is much larger than Tomas-Fermi length. However, under parameters values corresponding to the C60 molecule, when these lengths are of the same order, both these plasmons (providing the main contribution to the fullerene absorption spectrum) are found to be actually volume ones in their spatial structure, and the frequency of the higher of them becomes larger than the plasma frequency (as with all the higher volume plasmons). The resonance curve of the fullerene absorption cross-section calculated on the basis of the developed model with allowance for the surface losses caused by the reflection of electrons at the shell boundaries agrees satisfactory with the experimental data.