High Resolution¹³C NMR in K-Graphite Intercalation Compounds–C-Axis Charge Distribution

Abstract

High resolution 13 C NMR has been observed in highly oriented crystals of pristine graphite and K-GIC's. The NMR spectrum consists of several well resolved lines which can be assigned to the interior and bounding carbon layers. The 13 C spin-lattice relaxation time T 1 shows the metallic characteristics, T 1 T = constant between about 1.5 K and R.T. From T 1 of each resolved absorption line, the c-axis charge distribution was quantitatively determined for stage 3 and 6, which is strongly inhomogeneous. The obtained distribution was also supported by an analysis of the frequency shift of 13 C NMR. In stage 1 it was suggested, from a comparison of T 1 with electronic specific heat, that the conduction electrons near the Fermi level spread over not only graphite layers but also interlayer space containing K-atoms.