Far-Infrared investigation of C60 high-pressure-high-temperature polymers and dimer

We report high-resolution far-infrared transmission measurements on 2D rhombohedral and 1D orthorhombic high-pressure-high-temperature C60 polymers and the doubly-bonded dimer, between 20 and 650 cm-1. Symmetry-breaking of the linked C60 balls is evident in splittings and activations of intramolecular modes. We find overall good agreement with predictions of group theory for the reduced-symmetry point groups of the R-polymer and Dimer. An overabundance of activated modes between 500 and 600 cm-1 in the O-polymer makes a confirmation of its symmetry more tentative. In all three structures, a strong multiplet near 610 cm-1 suggests a very large splitting or frequency shift of an Ih C60 fundamental mode, implying that a weak perturbation model cannot adequately describe the vibrational properties of bonded fullerenes.

Keywords:

• far infrared
• fullerenes
• vibrations
• symmetry-breaking