We report high-resolution far-infrared transmission measurements of the (Formula presented) cycloaddition (Formula presented) dimer and two-dimensional rhombohedral and one-dimensional orthorhombic high-pressure high-temperature (Formula presented) polymers. In the spectral region investigated (Formula presented) we see no low-energy interball modes, but symmetry breaking of the linked (Formula presented) balls is evident in the complex spectrum of intramolecular modes. Experimental features suggest large splittings or frequency shifts of some (Formula presented) modes that are activated by symmetry reduction, implying that the balls are strongly distorted in these structures. We have calculated the vibrations of all three systems by first-principles quantum molecular dynamics and use them to assign the predominant (Formula presented) symmetries of observed modes. Our calculations show unprecedentedly large downshifts of (Formula presented) modes and extremely large splittings of other modes, both of which are consistent with the experimental spectra. For the rhombohedral and orthorhombic polymers, the (Formula presented) mode that is pola along the bonding direction is calculated to downshift below any (Formula presented) modes. We also identify a previously unassigned feature near (Formula presented) in all three systems as a widely split or shifted mode derived from various silent (Formula presented) vibrations, confirming a strong perturbation model for these linked fullerene structures.
|Number of pages||11|
|Journal||Physical Review B - Condensed Matter and Materials Physics|
|Publication status||Published - 2000|
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics