Low Frequency Raman Active Vibrations in Fullerenes. 2. Quadrupolar Modes

The lowest frequency Raman active (molecular) vibrations of known fullerenes are quadrupolar in nature (QP modes). They can be simply rationalized in terms of the 5-fold degenerate D<INF>g</INF> oscillation of an isotropic spherical shell. Symmetry distortion away from spherical leads to lifting of the degeneracy and correspondingly up to five vibrational features may be resolved in the QP-mode regions of the Raman spectra of high fullerenes. The energy splitting is a measure of fullerene cage topology.