ABSTRACT
This unusual behavior of the Raman-active phonon modes in CXF materials can be understood in light of the optical reflectance spectra for fluorine-inter calated GICs [2], which show that the plasma frequency in fluorine-inter calated HOPG-based GICs increases to a maximum at 3.46 eV for C6F and then decreases to about 3.0 eV for C33F (see Sec. VI). Ohana et al. [2] found that the charge transfer per fluorine atom decreases monotonically as a function of the fluorine concentration, consistent with the conductivity results [17,18] dis cussed in Section III.A.
