Isotopically resolved Raman spectra ofC60

We present high-resolution Raman spectra of ${\mathrm{C}}_{60}$ molecules. The totally symmetric mode near 1470 ${\mathrm{cm}}^{\mathrm{-}1}$ shows a fine structure which is almost exactly isomorphic with the mass spectrum of the molecule. We show that this surprising result can be explained in terms of isotopically induced frequency shifts and the unique icosahedral symmetry of the molecule. A comparison of predicted and observed isotope shifts provides a stringent test of vibrational theories for ${\mathrm{C}}_{60}$.