Specific Raman Signatures of a Dimetallofullerene Peapod

Abstract

We report on the Raman spectroscopy of a dimetallofullerene peapod, $({\mathrm{L}\mathrm{a}}_{2}@{\mathrm{C}}_{80}{)}_{m}@\mathrm{S}\mathrm{W}\mathrm{N}\mathrm{T}$. Drastic changes are observed with respect to pristine nanotubes. A sharp intense line at $142\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}1}$ is interpreted as a signature of polymerization of the encapsulated metallofullerenes. Additional strong signatures appear at about 400, 520, and $640\text{ }\text{ }{\mathrm{c}\mathrm{m}}^{\ensuremath{-}1}$, respectively. Their intensity suggests the existence of an enhancement effect. The stiffening and the up-shift of the $G$-band modes appear to imply that a charge transfer process between the nanotube and the peas occurs.