Raman study of C₆₀/polymethyl methacylate film

C₆₀/polymethyl methacylate (PMMA) composite films were prepared by the sol-gel method. Fourier transform infrared spectra of the as-prepared samples showed that C₆₀ is incorporated into PMMA and its structure is retained in the fabrication process. A substantial red shift of the high frequency, the A_g(2) pentagonal pinch mode, was observed from Raman scattering measurement at room temperature. To our knowledge, this is the first time to find such phenomenon correlated with the charge transfer between the two phases in C₆₀/PMMA films. Moreover, the phonon softening was compared with a theoretical calculation performed in graphite intercalation compounds. The charge transfer effect was also evidenced with ultraviolet-visible observations.