Raman Spectroscopic Studies of Buckminsterfullerene and Related Compounds

In this dissertation, Raman spectroscopic techniques have been used to study the vibrational properties of C _{60}, and alkali-doped C_{60}. Optical transitions in these systems have also been probed using resonance Raman techniques. A detailed study of the isotopic shifts in the Raman spectrum of C_{60} is presented and a new assignment of silent-modes in C_{60} is made. This assignment is consistent with other high-resolution Raman scattering, infrared absorption and neutron scattering. Raman spectrum calculations of natural and isotopically enriched C_{60} have been performed using a bond polarizability model. A new set of bond polarizability parameters for C_{60} have been obtained by fits to the Raman spectra of C _{60} obtained with off-resonance near-infrared excitation. These parameters are close to the bond polarizability parameters of hydrocarbons and can be used to predict the Raman spectrum of C _{70} and other higher fullerenes. Resonance Raman studies of the A_ {rm g}(2) mode in frozen solutions of C_{60} dissolved in CS_2 show an enhancement near 2.5 eV. This is similar to the results previously obtained for crystalline C_{60}, further confirming the fact that Raman excitation profiles near 2.5 eV in frozen solutions of C_{60 } are due to external perturbations causing the loss of inversion symmetry. Raman excitation profiles for the various modes in polycrystalline rm K_6C_{60} have been obtained. All the Raman active modes (both nondegenerate and degenerate) in rm K_6C_{60} show a common two peak structure in the excitation profile.