RAMAN-SCATTERING AND LATTICE-DYNAMICS OF FULLERIDES MXC60

A review of our investigations of Raman spectra of intramolecular and external modes in pristine and doped fullerene C60 is given. Experimen tal results are compared with group-theoretical predictions. In low-fr equency spectra of M6C60 new bands are found that we have assigned to external modes. An intepretation of M6C60 external modes and lattice d ynamics calculations are carried out. From an analysis of the excitati on profile of resonant Raman spectra it is found that expected changes of internuclear distances in the excited state of C60 should be close to the form of the A(g) mode at 1468 cm-1. Moreover, a destructive in terference of A(g) modes in M3C60 and M6C60 is observed. The essential broadening, a shift and the Fano lineshape of low-frequency intramole cular H(g) bands in metallic M3C60 are found. A narrowing of these ban ds in insulating C60 and M6C60 indicates the strong electron-phonon in teraction of H(g) Jabn-Teller modes. An estimation of the electron-pho non coupling constants for some modes is given. A possible origin of l ow-energy electronic excitations appearing in M3C60 resonant Raman spe ctra at lambda(i) = 1064 nm excitation is discussed.