Raman study of the temperature-induced decomposition of the two-dimensional rhombohedral polymer of C60 and the intermediate states formed

Raman spectra of single crystalline two-dimensional rhombohedral (2D-R) polymer of C60 were measured at ambient conditions after its high temperature treatment (HTT) in order to study the polymer decomposition process. The data obtained indicate that the 2D-R polymer remains stable after 0.5 h treatment up to ∼503 K, while at higher temperatures a material transformation takes place. New Raman lines appear in the Raman spectrum after HTT in the range of 513–553 K, related to the Ag(2) pentagon pinch (PP) mode of 2D tetragonal-like (2D-T-like) and 1D orthorhombic-like (1D-O-like) oligomers as well as to C60 dimers and monomers, typical for an intermediate state of partially decomposed 2D-R polymer. Above 553 K, the material changes completely and its new composition is dominated by C60 monomers with some possible inclusion of C60 dimers. The activation energy of the 2D-R polymer decomposition, obtained from the dependence of the decomposition time on the treatment temperature, is EA = 1.76 ± 0.07 eV/molecule.