Comparative Raman study of the 1D and 2D polymeric phases of C-60 under pressure

The effect of symmetry lowering on the phonon spectra as well as the pressu re effects on the vibrational spectrum of polymerized C-60 were studied by Raman spectroscopy. Drastic changes related to the splitting of degenerate modes of the C-60 molecule were observed together with selected softening o f some of them. In spite of many similarities in the Raman spectra of the o ne(1D) and two-dimensional (2D) polymeric forms of C-60, some salient diffe rences in the peak intensities and the appearance of complementary modes ar e evident. In the Raman spectrum of the 2D polymer under high pressure, new modes, which may be related to the deformations of molecular cages, appear . The observed pressure effects are reversible and the material remains sta ble for pressures up to 8.8 GPa.