Raman spectroscopy of undoped and doped single crystal C/sub 60/

Summary form only given. We present high resolution Raman spectra of undoped single crystals at low temperatures using laser exitations in the red and green spectral range. A splitting of the H/sub g/ modes in A/sub g/, E/sub g/ and F/sub g/ modes was found. A maximum of 8 splitted components could be observed. The doping of the single crystals with potassium was performed at temperatures slightly above room temperature and the doping process was studied by using in-situ Raman spectroscopy. Up to the penetration depth of the laser homogeneous single phases of K/sub 1/ C/sub 60/ and K/sub 3/C/sub 60/ could be obtained. The doped phases were identified by the position of the A/sub g/ pinch mode, which is very sensitive relative to the charge transfer. At cooling the high temperature phase K/sub 1/C/sub 60/ was observed to undergo a sharp transition into C/sub 60/ and K/sub 3/C/sub 60/ between 430 K and 410 K. In addition temperature dependent Raman measurements were performed on single phase K/sub 3/C/sub 60/. At liquid nitrogen temperature an unexpected strong splitting and selective line broadening of the H/sub g/ modes was observed.