Low frequency Raman active vibrations in fullerenes. 2. Quadrupolar modes

The lowest frequency Raman active (molecular) vibrations of known fullerene s are quadrupolar in nature (QP modes). They can be simply rationalized in terms of the 5-fold degenerate D-g oscillation of an isotropic spherical sh ell. Symmetry distortion away fi-om spherical leads to lifting of the degen eracy and correspondingly up to five vibrational features may be resolved i n the QP-mode regions of the Raman spectra of high fullerenes. The energy s plitting is a measure of fullerene cage topology.