Raman response of stage-1 graphite intercalation compounds revisited

Abstract

We present a detailed in-situ Raman analysis of stage-1 KC8, CaC6, and LiC6\ngraphite intercalation compounds (GIC) to unravel their intrinsic finger print.\nFour main components were found between 1200 cm-1 and 1700 cm-1, and each of\nthem were assigned to a corresponding vibrational mode. From a detailed line\nshape analysis of the intrinsic Fano-lines of the G- and D-line response we\nprecisely determine the position ({\\omega}ph), line width ({\\Gamma}ph) and\nasymmetry (q) from each component. The comparison to the theoretical calculated\nline width and position of each component allow us to extract the\nelectron-phonon coupling constant of these compounds. A coupling constant\n{\\lambda}ph < 0.06 was obtained. This highlights that Raman active modes alone\nare not sufficient to explain the superconductivity within the electron-phonon\ncoupling mechanism in CaC6 and KC8.\n