Raman scattering of stage 2 graphite fluorine intercalation compounds

Raman scattering spectra of stage 2 graphite fluorine intercalation compounds are presented and discussed. The concentrated sample shows four narrow lines at 1392, 1444, 1590 and 1614 cm^-1. The dilute C₁₂F spectra display two relatively broad lines centred at 1358 and 1605 cm^-1. Analysis of these results indicates that the fluorine interacts rather strongly with the carbon layers giving rise to a doubling of the Brillouin zone and possibly to a splitting of the Ê_2g2 mode. The lines at 1392 and 1444 cm^-1 are interpreted to arise from Brillouin zone folding, while the lines at 1590 and 1614 could be the result of either folding of the M point to the zone centre or a splitting of the Ê_2g2 mode. The line at 1358 cm^-1 in the dilute compound is interpreted as disorder induced.