EPR study of the crystalline polymerized phases of C_(60)

摘要

Comparative electron paramagnetic resonance (EPR) study of the monomer and 1D (orthorhombic) and 2D (tetragonal and rhombohedral) polymerized phases of C_(60) has been carried out. It was shown that the concentration of paramagnetic centers (PC) depends on the phase structure. Temperature dependences of the EPR spectra enabled separation of temperature-dependent from temperature-independent components of the main doublet signals, which were attributed to C_(60)~+ radical (PC1) and to conducting electrons, respectively. Additional weak EPR signals, observed for the tetragonal and rhombohedral phases, were attributed to dimer PC2 formed by coupling of two PC1. Possible models for these centers are discussed.