Electron--Vibron Interactions in Charged Buckminsterfullerene: Pair Energies and Spectra (Part II)

TL;DR

This paper extends the electron-vibron Hamiltonian to include all relevant modes in charged buckminsterfullerene, calculating energy shifts and spectra, with implications for superconductivity and spin measurements.

Contribution

It provides a comprehensive calculation of energy shifts and vibrational spectra for charged C60 ions, including all modes and their effects, advancing understanding of electron-vibron interactions.

Findings

Complex splitting patterns of H_g vibrational levels identified.

Enhanced electronic pairing interaction due to Jahn Teller effect.

Relevance to EPR measurements and spectroscopic experiments.

Abstract

The ground state energy shifts and excitation spectra of charged buckminsterfullerene C$_{60}^{n-}$, $n=1,\ldots 5$ are calculated. The electron--vibron Hamiltonian of Part I is extended to include all $A_g$ and $H_g$ modes with experimentally determined frequencies and theoretically estimated coupling constants. Complex splitting patterns of $H_g$ vibrational levels are found. Our results are relevant to EPR measurements of spin splittings in C$_{60}^{2-}$ and C$_{60}^{3-}$ in solution. Spectroscopic gas-phase experiments will be of interest for further testing of this theory. As found in Part I, degeneracies in the electron and vibron Hamiltonians give rise to a dynamical Jahn Teller effect, and to a considerable enhancement of the electronic pairing interaction. This helps to overcome repulsive Coulomb interactions and has important implications for superconductivity in K$_3$C$_{60}$ and the insulating state in K$_4$C$_{60}$.