Raman Scattering from Nonresonant Intercalant Modes in Stage-1 C-AsF5

Nonresonant Raman scattering from intercalant vibrational modes in graphite intercalation compounds, measured on the $a$ face, is reported here for the first time. The penetration depth of light with polarization $\mathbf{E}\parallel \mathbf{c}$ is enhanced by 2 orders of magnitude compared with the penetration depth of light with $\mathbf{E}\perp \mathbf{c}$. We have observed in stage-1 C-As${\mathrm{F}}_5$ three lines at 683, 698, and 753 ${\mathrm{cm}}^{-1\mathrm{}}$. They are identified as the breathing modes of the intercalant molecules As${\mathrm{F}}_6^{-}$, As${\mathrm{F}}_3$, and As${\mathrm{F}}_5$, respectively.