Structure and spectroscopy of graphite monofluoride

Abstract

The structure of graphite monofluoride, (CF)n, has been debated since its discovery in 1934. In this work, we investigate a commercial graphite monofluoride by vibrational spectroscopy (infrared, Raman and the first inelastic neutron scattering spectra of this material). The spectroscopy shows that the material contains unreacted graphite and the partially fluorinated product dicarbon fluoride, (C2F)n, We evaluate the previously proposed P6̅m2 and P3̅m1structures using computational methods and find F···F contacts render the P6̅m2 structure dynamically unstable. We propose two alternative structures, Cmc21 P63mc, generated by displacement of one layer relative to another and find that Cmc21 is also dynamically unstable. The calculations are validated by comparison of calculated and observed INS spectra