Gunnarsson O., Liechtenstein A.I., Eyert V., Knupfer M., Fink J., Armbruster J.F.
Inelastic energy loss measurements of the 0.5 eV charge carrier plasmon in K3C60 are presented, showing that the plasmon has a very large broadening but a negligible dispersion. The response function is calculated in a self-consistent, conserving approximation, showing that the plasmon broadening can be explained in terms of a decay in electron hole pair(s) under the emission of phonon(s). The negligible plasmon dispersion can be understood within the random phase approximation. Local-field effects tend to give a large negative dispersion, which is compensated by interband effects.
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